1. Total Quality Management : Its Relevance in Oils, Soaps, Detergents Industries

Introduction
Magnitude of OSD
Oil Industry
Soap Industry
Detergent Industry
General
Solvent Extraction Industry
Exports by Major Soap Industries in India
Quality Control Systems
Standardisation
Statistical Quality Control (S.Q.C.)
Productivity Applications
Oil-Soap-Detergent Industries (OSD)

2. Packaging Criteria for Cosmetics and Toiletries

Evolution of Packaging
Functional Requirements of Packaging
Technical
Aesthetic
Cost
Chemical Compatibility
Physical Compatibility
Retantion of Volatiles
Leak proof caps
Tamper-proof Seal
Transport Hazards
Aesthetic Factors
Presentability/Appearance
Packaging Design
Package Design - Practicability
Cost-effectiveness of Pack
Packaging Materials
Glass
Metal
Plastics
Papar
Product Evaluation
Transit Trials
Products Characteristics and Packaging Materials
Legal Requirements
Closing
Specification for Polycoated Paper
Specification of Gum Tape
Specification of Corrugated Fibreboard Boxes

3. Principal Groups of Synthetic Detergents
Classification
Anionic Detergents
Alkyl Aryl Sulphonates
Long-Chain (Fatty) Alcohol Sulphates
Sulphonated Olefins
Sulphated Monoglycerides
Sulphated Ethers
Sulphosuccinates
Sulphonated Methyl Esters
Alkane Sulphotes
Phosphate Esters
Alkyl Isethionates
Acyl Sarcosides
Alkyl Taurides
Fluorosurfactants
Cationic Detergents
Non-ionic Detergents
Fatty Acid Condensates
Condensation of Ethylene Oxide with an Amine
Condensation of Ethylene Oxide with an Amide
Block Polymers
Sucrose Esters
Sorbitan Esters
Alkylolamides
Fatty Amine Oxides
Amphoetrics and Zwitterionics
Biodegradability

4. Application and Formulae of Detergents
Foam
Household Cleaning
Heavy-Duty Laundering
Foam Control
General-Purpose Detergents
Choice of Non-Ionic
Concentrated Powders
Cold Water Washing
Hard-Surface Cleaners
Machine Dishwashing
Abrasive-Type Cleaners
Miscellaneous Household Cleaners
Commercial Laundering
Solvent Detergents
Carpet and Upholstery Cleaners
Textile Dressing
Mercerizing
Food and Dairy Industries
Detergent Sanitizers
Metal Cleaners
Miscellaneous Cleaners
Lavatory Cleaner
Hand Cleaners
Waterless Hand Cleansers

5. General Discussion of Detergents
Industrial-Detergents - Applications
Cosmetic Industry on Path of Progress

6. Detergent Bar
Formulation
Sequence of Additions
Note
Specification
Type of Defects
What are the main defects in bar detergent?
Detergent Bar Cost Calculations

7. Liquid Soap and Detergents
Product Introduction
Method of Manufacture
Liquid Detergents
Weight Equivalents of DDBSA
Molecular Weights
Special Procedures for Compounding

8. Washing Soap: Laundry Soap Formulation
Manufacture of Laundry Neat soap from Oil Blend
Harding of RBD
Acid wash for RBHT
Salt Wash for Neem Oil
Blending
Neem Soap Manufacture
Manufacture of Laundry Soap
Theory
Process and Raw Material
Product Profile
Washing Soaps
Brand Name

9. Deodorant
Zinc Ricinoleate
Deodorant pump Spray
Name of the Manufacturers
Zinc Ricinoleate
Market Size of Deodorant
Growth Barrier

10. Tooth Paste
Introduction
Consumers and Predicted Demand
Production Target and Quality Control
Requirement of Land and Building
Availability of Raw Materials
Machinery and Equipment
Office Equipment
Man Power Required
Raw Materials Per Month

11. After Shave Lotion
Introduction
Uses of After shave Lotion
Market Position
Advertising
Distribution
Formulations with Process
Process
Note
Process
Plant Economics
Land and Building
Plant and Machinery
Raw Material (Annual)
Utilities and Overheads (Annual)
Personnel Requirement (Annual)

12. Hair Shampoo
Introduction
Properties
Uses and Application
Raw Materials for Shampoos
The Nonionic Detergent Raw Materials
Amphoteric Products
Perfumes
Preservatives
New Shampoo Development
Protein and Egg Shampoo
Herbal Shampoo
Vitamin Shampoos
Antidandruff Shampoos
Market Survey
Present Manufacturers
Formulae
Coconut oil Shampoo
Triethanolamine Shampoo
Liquid Cream Shampoos
Liquid Cream Shampoo
Procedure
Manufacturing Process

13. Antiseptic and Germicidal Liquid Soap
Hexachlorophene Soaps
Control of Clarity
Filtration
Bottling and Packaging

14. Fundamentals of Science
Weight
Measurements
Volume
Units
Measurement
Examples
Density and Specific Gravity
Temperature
Diversion
Pressure and Vacuum
Surface Tension
Viscosity
Flow
Acid, Bases and Neutral Solution
Normal Solutions and Normality
Unloading of Oleum tanker
Process Familiarisation
Raw Materials Characteristics and Storage
Hydrocarbon
Caustic Soda
Other Process Chemicals and Ingredients
Bleach liquor

15. Raw Material Specification
Oils/Fatty Material
Chemicals

16. Testing of Finished Goods
Report for the Central Laboratory (Test of Oil)
Determination of Moisture
Determination F. F. A.
Determination of Iodine value
Colour
Specification Value
Unsap Value
Mineral Oil
Caster oil test
Bleaching of oil
Wesson loss
Test for HCN

17. Finished Product Quality Control Procedures
Oven Volatilise
Scope
Apparatus
Procedure
Calculation
Determination of Total Fatty Matter
Procedure
Alcohol Insoluble matter
Detergent Powder
NSD Manufacture in Brief
Powder
Sulphonation
Neutralisation and Bleaching
Slurry Preparation
Blowing of Slurry
Filling and Packing
NSD-Bar
Mixer
Noodler and Mill
Plodder
Billeting
Weathering

18. Analytical Testing Methods

Aluminium Sulphate
Determination of pH
Determination of Iron
Determination of Aluminium
Purity of Calcite
Moisture Content - Calcite
Matter Soluble in Water
Determination of Alumina
Iron As Fe2O3 (Total and Free)
Loss on Drying
Determination of Silica
China Clay - Paste with Glycerine
Loss on Ignition
Matter Soluble in Water
Matter Soluble in Acid
Water Absorption Value
Determination of Calcium and Magnesium In Dolomite
Moisture Content
Matter Insoluble in Acid
Bulk Density of Dolomite
Determination of Available Lime (as Cao)
Solubility of Liquid Paraffin
Reaction of Liquid Paraffin
Readily Carbonisable Substances in Liquid Paraffin
Sulphur Compounds in Liquid Paraffin
Reaction to Acid and Alkali
Solubility in Water
Colour Value
Determination of Matter Insoluble in Water
Volatile Matter Content
Total Alkalinity as Na2CO3
Determination of Chlorides
Determination of Sulphates
Iron Content
Determination of Iron (as Fe)
Total Soluble Silicates and Na2O : SiO2 Ratio
Moisture
Temperature Rise Test
Phosphorus Content
Determination of Tripolyphosphate Content (Na5P3O10)
Active Detergent Content of Detergent Paste
Total Anionic Detergent: Hyamine titration
Moisture and Volatile Matter of Detergent paste
Colour of Detergent Paste
Available Chlorine
Non-Detergent Organic Matter

19. Natural Essential Oils in India : A Perspective
Introduction
Essential Oils in India and Trade
Summary and Conclusion

Plant Economics

Directory Section

Development Council for Soaps, Detergents, Cosmetics and Toiletries Industries Reconstituted

^ Top

Application and Formulae of Detergents

Foam

It is expedient, however, that a few words be said on foam. At one time the amount of foam formed by a detergent was considered to be a measure of its effectiveness. It is true that foam is formed when surface tension is low, but lowering of surface tension is not always a criterion of detergency because this is in actual fact related to the lowering of interfacial tension.

In certain detergent operations high foam is a definite requirements, in certain cases it is immaterial whether the detergent foams or not, and in other cases foam can be considered a nuisance if not a prohibition to the use of the detergent for a particular operation.

It is obvious that a hair shampoo, shaving cream (other than the brushless type) and bubble bath preparations need to produce copious foam. Dishwashing compounds which are primarily meant for washing by hand in a sink full of water also need to foam copiously but the reason is not so obvious. As the plates are dipped in the solution and washed the oil is freed from the surface of the plate and floats to the top of the solution and in time this fatty layer can become appreciably thick. When the plate is withdrawn from the liquid it will pass through this layer last and part of the oil might become redeposited on the surface. If, however, a thick foam is developed in the liquid by the physical actions of washing, the oil will be trapped in the tremendous surface area of the foam and the amount of oil available for redeposition on the plate in its passage out of the solution is greatly reduced. When the foam becomes saturated with oil it collapses and this is an indication that the solution is no longer suitable for washing. For detergents intended for hand-washing of clothes foam is desirable as a sales-appeal factor.

Commercial and automatic household laundry machines are almost without exception 'foam sensitive.' If the detergent foams unduly the foam overflows on to the floor and also can interfere with the free flow of clothes through the water. In automatic machines the foam can interfere with water level pumps and the proper working of the control in the machine. A small amount of foam is necessary as this trends to trap dirt particles.

Similarly, dishwashing machines cannot tolerate foam, firstly because again the foam might overflow and also interfere with the pumping of the liquid and secondly, once foam forms, bubbles remain on the dishes and leave spots on drying.

Hard and fast rules cannot be laid down as certain household washing machines (usually those with a propeller) can tolerate foam, and in dish washing machines using a propeller a small amount of foam is not harmful but in the case of those working with jets the smallest trace of foam leave spots on glassware.

From our experience we can lay sown the following guidelines for foam :

1. Anionic detergents in general produce voluminous foam; somewhat less is produced in hard water but foam is always increased with an increase in temperature.
2. Non-ionic detergents foam considerably less than anionics, but this depends on the type of non-ionic. There are 'low-foam' non-ionic which can be used alone for most operations, while other non-ionic still need 'foam control'. Non-ionics usually foam somewhat less in hot water than in cold.
3. When soap is added to an anionic detergent, foam is depressed.
4. Non-ionic detergents do not depress foam of anionics; they can even enhance it.
5. Alkaline builders in general enhance the foaming power of all type of detergents.

We shall later in this chapter include formulations for both powders and liquids with foam control but cognizance should be taken of Proctor and Gamble patent whereby a foam control agent is added to a ready-made powder.

The patent describes a combination of white mineral oil, paraffin wax of microcrystalline wax and/or glycerol monostearate and microfine precipitated hydrophobic silica in the proportions :

Mineral Oil	80 parts
Paraffin wax or microcrystalline wax and/or glycerol monostearate	2-12 parts
Microfine hydrophobic silica	0.31-1 parts

The solid waxes are dissolved in the oil with warming and the silica dispersed in it.

To give a non-foaming detergent, 100 parts of finished powder are sprayed with one part of this solution/dispersion.

Household Cleaning

The days of one bar of soap, which served as a hair shampoo, toilet bar, laundry soap, for general washing and (mixed with sand from the garden) for pot-scouring, have long since passed. Nowadays, materials are manufactured for special purposes, such as heavy-duty laundering (the washing of cotton goods which by their very nature are usually heavily soiled), fine wash (the laundering of delicate fabrics such as silks, nylons, woollens), general purpose, dishwashing, floor-washing, window-cleaning, tile-cleaning, etc.

Heavy-Duty Laundering

Detergents should be formulated with the type of clientele in mind. Werdelmann has made a study of the differences between European and American washing habits.

The obvious differences are that Europeans use a front-loading, rotating drum washer whereas the Americans use a top-loading agitator machines. The Europeans also wash at a higher temperature than the Americans. These two factors require European powders to be low-foaming, while American machines can tolerate a moderate-foaming washing powder or liquid.

Without going into details we also quote the figures for the range of hardness of water :

Hardness parts/106

	0-90	90-270	270 and higher
USA	60%	35%	5%
Europe	9%	49%	42%

Although these figures can be meaningless for the continents as a whole, they do provide some indication.

Again washing habits both personal and for clothes differ greatly in the two continents. Table 1 shows the comparison of formulae of heavy-duty detergents quoted.

Table 1: Comparison of Formulae of Heavy-duty Detergents

	USA	Europe
Surfactant	10-20	20-15
STP	35-60	35-45
Sodium silicate	4-10	3-5
Sodium perborate	-	20-35
Optical brighteners	0.1-1.0	0.7-0.8
Dosage	1-2 g/litre	7-8 g/litre
Clothes : liquid ratio	1:15-1:25 kg/litre	1:5 kg/litre

Since this report was published, however, perborate together with an activator are gradually appearing on the US market. Enzymes which had their ups and downs in the USA are also increasing in popularity.

Non-ionics perform better than other detergents on fabrics made from synthetic fibres and also under cold water conditions. They also find use as 'rubbing agents' for badly soiled collars.

Cotton goods, which are still the bulk of the household wash require a moderately high alkalinity. In contact with a solution of a pH of 10 or more, the cellulose fibre swells slightly, allowing the water to penetrate into the fibre and thus loosen adhering dirt.

Household heave-duty washing powders are generally of two types for hand washing and for fully automatic washing machines. The hand-washing type of powder requires a copious lather for psychological reasons. Fully automatic washing machines, which have a drum which revolves around a horizontal axis, cannot use a power with a copious foam. Because of the action of the drum, the foam can spill out of the machine, and also the foam interferes with the action of the automatic floats which adjust the level of the water. However, a small amount of foam is necessary, as some of the dirt is trapped by this foam. For these reason the powder has to have 'controlled foam'. Semi-automatic machines, i.e., those that have propellers or impellers to do the agitation, or with drums rotating about a vertical axis, can in general, utilize either of the two types of powders.

A formulation for a hand-washing or semi-automatic machine, manufactured by simultaneous absorption and neutralization, has already been discussed in Chapter 6. Formulae 2 and 3. The addition of sodium perborate is, of course, optical and depends on washing practices in the particular area. We recommend the addition of at least 10 per cent sodium perborate to all laundry powders. In countries where this is not normal practice the addition of sodium perborate might make the powder expensive, but the extra whiteness achieved will compensate for the increased cost.

If the powder is being manufactured by the spray-drying process, the formulation can, if desired, be the same as that given in Formula 2 or 3, but an infinitely better powder can be made by using Formula 9 :

Formula 9

Spray-dried Heavy-duty Household Hand-washing Powder

Sodium alkyl benzene sulphonate (or equivalent)	25
Sodium tripolyphosphate	25
CMC (66% basis)	2.5
Sodium silicate (1:2;4 ratio)	15
Optical brightening agent	0.2
Sodium sulphate	32.3

and to this powder after spray-drying add sodium perborate at the rate of

Spray-dried powder	90
Sodium perborate	10

Foam Control

The above formula cannot be used in form-sensitive washing machines. To overcome the foaming problem several methods of foam control are used. One is to use a low-foaming non-ionic detergent as the active matter. An alkyl phenol condensed with not more than eight molecules of ethylene oxide will not foam unduly, but the physical characteristics (free-flowing, stickiness) both of spray-dried powders and those made by others methods will suffer when using low ethylene oxide content non-ionics and therefore the amount of active matter it is possible to incorporate in the powder is limited.

A typical powder to be made by either spray-drying or spray mixing is given in Formula 10.

Formula 10

Heavy-duty Fully Automatic Washing Machine Powder

Non-ionic detergent (low-foaming)	10
Sodium tripolyphosphate	30
CMC (66% basis)	1.5
Sodium silicate (1 : 2.4 ratio)	15
Optical brightening agent	0.2
Sodium sulphate (can be partially replaced by soda ash)	43.3

Another trend is to use a moderately high-foaming non-ionic such as iso tridecyl alcohol with 15 molecules of ethylene oxide, tallow alcohol or alkyl phenol both with 10-12 molecules of ethylene oxide. All of these detergents foam quite highly, and to depress the foam a nonyl phenol with 1½ molecules of ethylene oxide is used. The addition of this foam-depressor is critical and if proportions different from the optimum are used the foam is likely to be enhanced. The amount suggested is normally 15 percent of the total active matter, but this figure should be checked against the particular type of active matter with the exact proportions of builders being used.

Sodium perborate can be added in the same manner as in Formula 9, if the powder is spray-dried. If the powder is manufactured by a spray-mixing process with arrangements for continuous discharge of the powder, the sodium perborate can be fed continuously on to the conveyor belt which receives the discharged powder. If not, the perborate can be incorporated batch-wise in a powder mixer. On we describe methods for the incorporation of perborate both continuously and batchwise.

To incorporate appreciable quantities of non-ionics into spray-dried powders, recourse must be made to the 'Pluronics, some of which are available as flakes, prills, or flakeable solids. Alternatively all the methods described on should be considered.

A simpler and cheaper 'controlled foam' powder can be made by the use of a mixture of soap and alkyl benzene sulphonic acid. This will give both lower foam and higher detergency that when either is used alone in comparable proportions. It has been found that the foam is at a minimum when the soap proportion of the total active matter is between 30 and 60 per cent. Outside these limits, foam begins to form. If hard water is prevalent in the area, the detergent/soap ratio should be richer in the synthetic portion. If there is predominantly soft water in the area, more soap can be used if required. A word of caution needs to be given in the use of soap or soap mixtures in automatic washing machines. Some automatic machines have their heating elements protruding directly into the water, while others have the elements protected by a sleeve, which disperses the initial heat over a greater surface area. If the element is itself immersed in the water, it has been found that in areas of moderate to very hard water, a layer of insoluble limesoap can form on the element, decreasing the efficiency of the heat transfer. This can to a certain extent be eliminated by the inclusion of NTA or EDTA in the formula, but this leads to a further complication in that both NTA and EDTA in the presence of oxidizing agents (perborate) are corrosive to copper and zinc. Inhibitors have been developed to minimize this corrosion to an acceptable level.

A powder of this type can be made by the absorption and neutralization process according to Formula 11.

Formula 11

Low-foaming Machine Powder for Soft-water Areas

Mix together with warming to 45°C

(a) LAS (100 per cent) 11.6

Distilled tallow fatty acid 6.4

In the powder mixer, mix together:

Sodium tripolyphosphate 15

(b) Soda ash light 55

CMC (66% basis) 2

When uniform, add (a) with mixing. When the LAS/tallow fatty acid mixture has been dispersed, add immediately in order

Sodium hypochlorite	2
Sodium silicate 40%	8

This is mixed for a few minutes until the reaction is seen to have been completed, and then discharged for ageing. Next day the powder is ground and recharged to the mixer in the following proportions :

Milled powder from Formula 6	90
Sodium perborate	10
Optical brightening agent	0.15

and mixed until uniform and then send to packing.

If one of the mixers is used the ageing and grinding can of course be dispensed with.

To manufacture the same formula using ready-made soap powder the formulation is :

Formula 12

Low-foaming Machine Powder for Soft-water Areas using

per cent fatty acids 7.9

Ready-made Soap Powder Mix together : Sodium tripolyphosphate	15
Soda ash, light	53.7
CMC (66% basis)	2
Add in order : LAS (100%)	11.4
Sodium hypochlorite	2
Sodium silicate	8
when the reaction is completed add : High titre soap powder	82
Thereafter proceed as in Formula	11

The same powder can of course be made by spray-drying, but a vastly superior one can be made in a spray-drier according to Formula 13. Modern tendencies are to manufacture 'ternary' powders, that is, powders having the active matter made up of three constituents, soap an anionic and a low-foaming non-ionic detergent, a formula for which is given in Formula 14.

Formulae 13-14.

Spray- dried Household Low-foaming Laundry Powders

	13	14
Sodium dodecyl benzene sulphonate (100% basis)	15	7
Tallow soap, soda based (100% basis)	10	5
Low-foaming non-ionic detergent	-	7
Sodium tripolyphosphate	15	15
Tetrasodium pyrophosphate (optical, can be completely replaced by Sodium tripolyphosphate)	10	10
Sodium silicate (anhydrous basis, ration 1:2.5)	7	7
CMC (66% basis)	2.5	2.5
Optical brightening agent	0.2	0.2
Soda ash	0-20	0-20
Sodium sulphate	to make	100

Sodium perborate is added at the rate of 10 per cent (or more if desired) after drying.

In place of tallow soap, the soap of behenic acid (a C22 saturated acid) is being used. Sodium behenate in the formulation acts mainly as a foam control agent (a very efficient one) and at a maximum concentration of 2 percent. The synthetic active agents can then be increased to give a more effective wash, even at low temperatures.

Behenic acid has a high melting point (80°C), therefore special precautions need to be applied for its introduction and saponification.

For dry neutralized powders it is best dissolved in the LAS and the liquid non-ionic (if being used) or a solvent with the aid of heat (for solvent detergent powders) and the mixture is sprayed hot on to the powders.

For spray-drying it can be dissolved in the LAS, and the mixture kept at a higher than normal temperature in the supply tank. The neutralized paste or slurry, which should also be kept at a higher temperature than normal, will probably have a higher viscosity than normal. Contrary to generally accepted principles, lowering the water content of the slurry slightly will, in this case, also decrease the viscosity.

As mentioned non-ionics can cause trouble on being spray-dried, pluming and also auto-oxidation.

Pluming can be minimized by the use of the narrow range ethoxylates. Auto-oxidation, which at best can discolour the fines and at worst will discolour the powder, can be inhibited according to a lever patent4 by the inclusion of about 1 per cent of charge transfer agent, two examples of which are stannic chloride or tetrachlorobenzoquinone. The most efficient methods of incorporation are of course the methods already described. These methods also tend themselves to the incorporation of enzymes, perborate etc.

Even in areas where there are no restrictions (total or partial) on the use of phosphates, consideration should be given to the use of zeolites, either the zeolite itself or the zeolite/silicate blend. This will have the added advantage, particularly in dry mixed or agglomerated powders, of surface adsorption. The zeolite can absorb on its surface larger amounts of liquid surfactants than the normal builders are able to, thus drier, more free-flowing powders with higher active matter can be produced.

Where there are bans or restrictions on the use of phosphate, the STP suggested in the formulations can be replaced by mixtures of zeolites on the one hand and NTA or one of the polycarboxylic acids.

Enzymatic laundry powders for automatic washing machines are now being produced in large quantities. It is difficult to give directions as to the amount of enzyme concentrate to add to powder as the concentration of the 'net' enzyme varies from manufacturer to manufacturer, but they give explicit instructions as to usage. Enzymes for washing machine powders are commonly used together with perborate. The enzyme operates while the temperature of the water is low and it is rapidly inactivated when the temperature reaches 60°C, perborate taking over. Although the manufacturers state that the enzymes are stable to perborate, this stability is only relative and if both enzymes and perborate are included in a powder, it is advisable to increase the enzyme concentration over that normally recommended. Formula 14 with little or no soda ash can serve as a useful base for enzymatic powders.

In all of the above and subsequent formulae which are to be spray-dried, consideration should be given to the addition of 3-5 per cent of sodium toluene sulphonate. This does not serve the purpose that it does in a liquid detergent. In this instance the function of the toluene sulphonate is twofold : it lowers the viscosity of the slurry, allowing a higher solids content, and also promotes the free-flowing characteristics of finished powder, particularly when linear alkyl benzene sulphonate is used. Also when powders are made by processes other than spray-drying, the inclusion of toluene sulphonate is essential if linear alkyl benzene sulphonate is being used.

Heavy-duty liquid detergents are now making headway for household laundering. The problem here is that the solution for efficient laundering needs a certain amount of alkali, sequestering agent and soil-suspending agent. To incorporate sufficient of these with a detergent into a solution which will stay bright and clear is not easy. As a result, new materials are coming on the market specially for this purpose and new techniques are being employed. Many patents for heavy-duty liquids are daily appearing in the literature and as a result the trend is to move away from conventional materials The active ingredient can be chosen from one or more of the alkyl benzene sulphonates, olefin sulphonates, paraffin sulphonates or ethylene oxide condensates. For reasons given below the anionic should preferably not be neutralized with a sodium ion, rather potassium or an ethanolamine. This condition cannot always be observed, particularly if paraffin or olefin sulphonates are bought as the already hydrolysed/neutralized solution.

The linear alkyl benzene sulphonates show better solubility in water than do the branched. For the production of liquids the choice should be in the lower register of molecular weight (C10-12 rather than C11-13). EniChem of Italy is fractionating its detergent alkylate into high and low 2-phenyl fractions. Again the high 2-phenyl fraction is more suitable for the production of liquids for reasons of solubility. True the detergency is somewhat lower than for the low 2-phenyl isomers, but the production of liquid detergents does require some compromises and the detergency can be enhanced in different ways.

On this score it should be pointed out that, contrary to expectation, the potassium salt of LAS is not more soluble than the sodium salt; it is less soluble. However, the potassium salts are used on occasion because the inorganic constituents are often potassium salts and to introduce a sodium salt would result in precipitation of the sodium salt of the inorganic compound by double decomposition. This also works the other way in that the potassium ion of the salt could precipitate the LAS. More often than not, however, the LAS is neutralized with an ethanolamine to obviate this problem.

The problem in heavy-duty liquid detergents (HDLD) formulations is incorporating the builders into the solution in such a way that the liquid has enough of all the necessary ingredients for efficient washing without detracting from the appearance of the product.

The builders in question are sequestering agents, which are usually phosphates; alkalis, which are invariably silicates; anti-soil redeposition agents (CMC) and optical brighteners.

Spray-dried heavy-duty powders invariably contain sodium tripolyphosphate as the sequestering agent, sometimes with the addition of other sequestering agents. Polyphosphates hydrolyse rapidly in neutral or acid solutions, first to a mixture of ortho-and pyrophosphates, and the pyrophosphates in turn hydrolyse further, albeit at a slower rate, to the simple phosphates. If the pH of the solution is 9 or higher, the hydrolysis of polyphosphates is slow5 so much so that a solution containing polyphosphates at this pH can be stored for a year at 25°C with no appreciable hydrolysis having taken place.

The solubility of sodium tripolyphosphate in pure water is 15 per cent at room temperature, but this figure will be considerably lower in the presence of other dissolved materials, particularly anionic, due to the common ion effect. The solubility of tetrapotassium pyrophosphate in water is over 60 per cent whereas the corresponding sodium salt is only soluble to the extent of 5 per cent. It is for this reason that tetrapotassium pyrophosphate is often used as a constituent of liquid detergents, however sodium salts need to be excluded almost completely because, due to the common ion effect, tetrasodium pyrophosphate can be precipitated from a solution containing both sodium and potassium ions. Again the use of pyrophosphate is a compromise as it does not have the sequestering and peptizing properties found in the polyphosphates.

Potassium tripolyphosphate, with a solubility in water of 55 per cent, has appeared on the market and this does not suffer from the same defect in that its sodium salt might precipitate due to the increased solubility of its sodium analogue.

Alternatively, phosphates are completely dispensed with the organic sequestering agents, such as sodium (or potassium) ethylene diamine tetra-acetate, or nitrilo triacetate6 are employed.

The alkali required is obtained from the colloidal silicates. Potassium silicate has been found to be superior to sodium silicate in this respect and silicates act as corrosion inhibitors against the action of phosphates on stainless steels.

However, to get sufficient of all three of the above ingredients into solution is virtually impossible, as the presence of one affects the solubility of the others. For this reason it is necessary to use a hydrotope, i.e., a solvent aid, a product which is itself soluble in the medium and aids in the solution of other products. There are a variety of these, but the most commonly used are potassium (or sodium) xylene, toluene, cumene or ethyl benzene sulphonates. These have to be used in relatively large quantities, of the order of 5-10 per cent of the finished product. They can either be sulphonated (or bought) as such, or else co-sulphated in the correct proportion with the original sulphonate, if the basic detergent is one of the sulphonate types.

Urea, apart from its other uses in the detergent industry, is an efficient hydrotrope as efficient as the lower alkyl sulphonates. However, it suffers from one disadvantage. If one considers its method of manufacture, the combination of carbon dioxide with ammonia :

CO2 + 2NH3 ® NH4 CONH2

Ammonium carbamate

NH4CO2NH2® NH2CONH2 + H2O

Urea

it is conceivable that industrial urea can contain small proportions of unreacted ammonium carbamate. In water solution this can hydrolyse :

NH4CO2NH2 + H2O ® (NH4)2 CO3

to ammonium carbonated. If the solution is alkaline, which it almost invariably is, a smell of ammonia will become apparent, which might be objectionable to some people. Thus if urea is to be considered as the hydrotope, the purchase specification should stipulate no ammonium carbamate to be present.

Berol of Sweden has developed potassium salts of lower molecular weight phosphate esters specifically as hydrotropes for the production of liquid detergents based on alkyl phenol ethoxylates in admixture with potassium tripolyphosphate. These phosphate esters have a further advantage in that they have detergent or wetting properties in their own right, thus aiding in the washing process, a property which none of the other hydrotropes can claim.

CMC now has to be brought into this solution. It is best incorporated by making a 10 per cent 'solution' separately, when it swells and forms a gel. This swelling and gelling, however, is influenced by ions already in solution and, if present, the CMC in a very short time precipitates out and sinks to the bottom. This problem can be overcome in three ways. One method is to adjust the density of the solution so that it is the same as the density of the precipitated CMC (±1.37) and the precipitate will therefore not settle. This is achieved by the addition of sodium sulphate or chloride. In another method carboxymethyl cellulose and methyl cellulose are used. Both cellulose compounds tend to precipitate from the solution. By itself, the methyl cellulose would normally rise to the top and the CMC by itself would normally sink to the bottom. By using this pair in equimolar proportions, however, they precipitate, but neither rise nor fall. Finally, Hercules Powder Co has brought on the market a new type of low molecular weight CMC which has excellent stability to HDLD solutions with high percentage of electrolytes.

With the incorporation of CMC as outlined above, one tends to get an opaque type of suspension. It is felt that once the solution tends to be thick and opaque, it should be made to look like a lotion, and the incorporation of sodium nitrate10 is said to give a better appearance and easier density control. Alternatively one of the opacifying agents mentioned can be used.

If it is decided to dispense with phosphates, one of the organic chelating acids neutralized preferably in this case by monoethanolamine, can be used. Alkalinity can also be obtained by excess monoethanolamine.

In the manufacture of these liquids, very often a sludge of insoluble material settles out. This has been identified as traces of iron contamination in the ingredients or even the water. The addition of 1 per cent triethanolamine, over and above any base needed for neutralization will eliminate this sediment.

Finally, it is desirable to incorporate an optical brightener in the solution. This is the least of the producer's problem, as optical brighteners are now available which are stable in water solutions. The amount is so small that this has no effect on the solubility of the other materials, nor have they any bearing on the solubility of the dye.

Thus, to summarize, the following formulae could be used as heavy duty liquid detergents.

Formulae 15, 16, 17, 18

Heavy-duty Liquid Detergents

18

	15	16	17
Alkyl aryl sulphonic acid (ABS)	10	20	9	12
Diethanolamine	3.6	7.2	3.3	4
Non-ionic (100%)	2	-	3	-
PVP (100°)	0.7	-	-	0.7
K4P2O7 (100%)	12	12	10	-
Potassium silicate (100%)	4	3	4	-
Monoethanolamine	-	-	-	3
EDTA	-	-	-	5
CMC (100%)	-	1	1	-
Potassium xylene sulphonate or other hydrotope	5	5	4	4
Optical brightening agent	0.1	0.1	0.1	0.1
Water to	100	100	100	100

All the above formulae are of the medium- to high-foaming type and thus unsuitable for fully automatic washing machines.

A formulation for a heavy-duty liquid detergent with a 'controlled foam, using the normal type of CMC is given in Formula 19 :

Formula 19

Heavy-duty Liquid Detergent with 'Controlled Foam'

Disperse with gentle mixing CMC (66% basis)	2
in water	18
Into a stainless-steel vessel equipped with a slow-speed stirrer charge : distilled coconut oil fatty acid	8
Water	25
Caustic potash (40% solution)	5
Stir and warm gently until the solution attains a clear and homogeneous appearance, then add with stirring in order : Non-ionic detergent	4
Monoethanolamine	1.7
LAS	4
NTA or EDTA (acid form)	1
Hydrotrope	8
Tetrapotassium pyrophosphate or Potassium tripolyphosphate	10
Potassium silicate (40% solution, 1 : 2.5 mol ratio)	10
Optical brightening agent	0.2

The CMC gel prepared above is now added, mixing continued, and water added to make this solution up to 100.

This will produce a lotion type of liquid. It is not necessary to 'saponify' by boiling, because if all the above directions are adhered to, the coconut fatty acid will be completely neutralized and no free unsaponified oil will be present.

PVP is being used with success in place of the CMC. The PVP is added as a 5 per cent pre-prepared solution, and the water adjusted accordingly. This will produce a clear solution, possibly with a slight haze due to insoluble matter sometimes found in poly-or pyrophosphates.

As mentioned trace quantities of iron contamination in the raw materials can cause a sludge of ferric hydroxide to separate. This separation is not always immediately visible and an insurance against this is the addition of 1 per cent triethanolamine to chelate the ferric ions. The iron will still be present in the solution, but inactivated.

The Gantrez resins were mentioned as chelating agents. GAF, the manufacturer, has published a detailed description of an addition use, that as a stabilizer for liquid detergent solutions containing non-ionics.

These resins are high-molecular-weight polymers with anhydride rings, which on hydrolysis with water form dibasic acids. Thus for a typical molecular weight of 40,000, the hydrolysed resin can have 250 dibasic acid groups per molecule. These need to be neutralized and in fact the maximum chelating action is attained at a pH of 10 minimum. These acid groups can also be esterified and in our particular field the esterification agent they suggest is a non-ionic detergent, which normally has a terminal -OH group available for reaction with a carboxylic acid. If the major portion of the carboxylic groups is esterified, an insoluble mass is obtained, but if a partial ester is formed (1 per cent non-ionic based on the weight of the resin), this serves as a stabilizing agent for non-ionic liquids.

The non-ionic of choice is an alkyl phenol with 15 ethylene oxide units and the procedure is important. A stock solution of the resin is made, the type suggested is Gantrez AN-149 (medium viscosity). Dissolve in water.

Non-ionic	10
Water	890

and raise the temperature to 90°C. Add slowly with stirring

Gantrez AN-149

100

keeping the temperature at 90°C, and continue stirring till a clear solution is obtained. (Caution, a large amount of foam might be formed in this esterification.)

A formulation we have found to give excellent results as a heavy duty liquid is

Water	4.0
Gantrez stock solution	10.0
NaOH (45% solution)	2.0
CMC	0.5
Nonyl phenol-9 ethoxylate	3.5
NaOH (45% solution)	29.0
Potassium silicate (1: 3 mol ratio, 36%)	51.0
Optical brightner, dye, perfume	qs

The solution is made at 60°C, every ingredient to be dissolved completely before the next one is added.

The first addition of caustic soda is to neutralize the Gantrez resin. The second is to convert the silicate to metasilicate. We have found that a mixture of potassium/sodium metasilicate gives better freeze-thaw characteristics than pure sodium metasilicate as recommended by GAF. This can also be reversed, to use potassium hydroxide and sodium silicate to achieve the same purpose.

Finally, mention must be made of the fact that in the United States, one of the giant soapers, after ignoring the liquid household heavy-duty market almost completely, introduced its new liquid heavy-detergent, and from all accounts, at the time of going to press, this liquid is making remarkable inroads into the existing liquid market and also taking a large portion of the powder business. From the press release, this liquid is more concentrated than normal liquid in the market, being termed ½ cup (rather than 1 cup for existing brands) and contains 12 active ingredients; four surfactants, anionic, non-ionic and cationic (thus it seems to have a softener built in), two builders stated to be citrate and laurate (the laurate is obviously a soap, they use it as a chelating agent), three 'stain fighters' (two enzymes and one chemical never before used in heavy duty liquids), two brightening agent and a 'revolutionary molecule that makes all the 12 ingredients work together', apparently a hydrotrope. The problem of inactivation of enzymes (the calcium ions are chelated) has obviously been overcome by a method known only to this company.

An interesting and new development in the liquid heavy-duty household laundering field is a liquid containing a mixture of active chlorine and anionic detergent. It had been generally considered that chlorine (derived from sodium hypochlorite) could not be stable in the presence of considerable amounts of organic matter. However, sodium toluene of xylene sulphonates seem to stabilize sodium hypochlorite and mixtures of sodium hypochlorite with sodium ether sulphates can now be produced with the chlorine reasonably stable for over three months.

Formula 20

Heavy-duty Liquid Detergent and Bleach

Sodium lauryl ether sulphate (60% concentration)	20
Sodium toluene sulphonate	5
Sodium hypochlorite solution (10% available chlorine)	75

Even better results have been obtained in using Dowfax 2A1, one of the range of alkylated diphenyloxide disulphonates of the generic formula

produced by Dow. In the 2A1 version 'X' is the sodium ion. This novel surface active material is stable in moderately strong alkali and acid solutions, in the presence of large amounts of inorganic materials and in solutions of oxidizing agents. The high stability of hypochlorite in admixture with di-sulpho-diphenyl type of detergent is due to the inertia against chlorination of the multisubstituted benzene ring, one of the rings being tri-substituted, the other di-substituted. To achieve maximum stability, it is suggested that the diluted Dowfax 2A1 be heated to 70°C together with 2 per cent of a 12 per cent active chlorine hypochlorite solution, then cooled to 30°C and 20 per cent of a 12 per cent active chlorine hypochlorite solution added. This will give a 2.5 per cent active chlorine solution stable for a reasonable period, when packed in a plastic bottle. For a 6 per cent active detergent solution the formulation could be :

Soft water	65.4
Dowfax 2A1	13.0
Sodium hypochlorite 12% active	1.6
heat to 70°C, then cool to 30°C and add Sodium hypochlorite, 12% active	20.0

Free alkalinity should then be adjusted by the addition of caustic soda solution to 0.5-1.0 per cent. This free alkalinity, in addition to stabilizing the hypochlorite, reacts with the water hardness lowering the pH for maximum disinfecting and bleaching action of the active chlorine.

In the field of light-duty detergents, or (as it is sometimes called) find wash, are the materials for washing delicate fabrics such as wool, nylon, silk, etc. Also, in general, this type of detergent is suitable for household dishwashing by hand as well.

Synthetic detergents first took a hold in the household for this purpose, and liquids consisting only of detergents diluted with water very quickly achieved a large sale and large quantities are still being sold. Nowadays, liquid detergents are more sophisticated than the plain solutions that were originally sold. They can be based on anionic detergents only, usually dodecyl or tridecyl benzine sulphonate, or can utilize a mixture of the above anionics with a non-ionic, or a sulphated either. In addition to foam boosters, these liquids can have viscosity increasers and cloud-point depressants Furthermore, they need not necessarily be transparent liquids, but can be opaque lotions.

The concentration of active matter present in a liquid detergent of this type varies from country to country, but an average figure is 12 per cent for the simpler liquids, but this can go up to 40 per cent for the more sophisticated market.

The cloud point of a detergent is an important factor in its sales appeal, as it is axiomatic that no housewife will buy a liquid which tends to deposit a precipitate or to cloud over on storage. Requirements for the actual cloud point will vary from place to place and no hard-and fast rules can be given. The cloud point naturally obtained from a particular concentration of active matter depends on the type of material used and the method of neutralization.

In general, the sodium salt of the alkyl benzene sulphonic acids, at a concentration of 12 percent active matter, gives a cloud point too high for commercial use. The diethanolamine and triethanolamine salts of the alkyl benzene sulphonic acids give a very low cloud point, lower than is needed generally. Thus for economic reasons, neutralization is usually done partially with caustic soda and partially with an ethanolamine.

Among the alkyl benzene sulphonates, all other things being equal, the cloud point of the neutralized solutions rises in the following order :

linear dodecyl benzene sulphonate;

linear tridecyl benzene sulphonate;

branched dodecyl benzene sulphonate;

branched tridecyl benzene sulphonate.

The viscosity of the final solution, all other things being again equal, rises in the same order.

In addition to the above factors, the method of sulphonation is important, since on this method depends the amount of free sulphuric acid present. When neutralized, the acid produced inorganic sulphates, both of which raise the cloud point and the viscosity. SO3 sulphonated material will give the lowest free sulphuric acid present; and normal oleum sulphonation will produce the highest. (The figure is normally as high as 7-8 per cent).

The factors involved in producing an acceptable liquid detergent are therefore dependent on :

1. the type of alkyl benzene sulphonate;
2. the method of manufacture of this sulphonate;
3. whether any other active material is used.

To taken an average case, if conventional dodecyl benzene, sulphonated with SO3, is to be used as the base material for the manufacture of a 12 per cent liquid, a cloud point of below 5°C can be obtained by neutralizing half of the active matter with caustic soda and the other half with diethanolamine of triethanolamine. The neutralization with diethanolamine will give a slightly higher viscosity than if neutralization had been done with triethanolamine. Diethanolamine is a solid, except in very hot climates, and therefore is more difficult to handle. On the other hand, when alkyl benzene sulphonate are wholly or partially neutralized with triethanolamine, which is a liquid, a buffer is formed at a pH of approximately 6. To pass this buffer, it is necessary to use a large excess of base. To preserve a low cloud point, it is not advisable to use too much caustic soda to overcome this butter, so a fair excess of triethanolamine must therefore be used. The manufacturer must consequently consider the disadvantages involved in handling diethanolamine against the extra cost of triethanolamine.

If in the examples of alkyl benzene sulphonates given above, one of the sulphonates which normally gives a low cloud point were to be used to maintain the same cloud point level, the proportion of caustic soda can be raised and that of the ethanolamine correspondingly reduced.

Furthermore, if an acid sulphonated material is used as the base material, the proportion of ethanolamine needs to be raised considerably (and the caustic soda to be lowered) to maintain the low cloud point.

If it is required to raise the viscosity of the solution, a simple but limited method is the addition of an inorganic salt, like sodium sulphate or sodium chloride. This is limited in that it raises the cloud point. A better and more efficient method of increasing the viscosity is the use of an alkylolamide, preferably a diethanolamide.

Because of the various factors involved in the formulation of a liquid, it is not possible to describe formulations for all possible permutations and combinations.

Formula 21 gives a basic formula to be used as a starting-point. The manufacturer is advised to modify this according to the conditions he requires and the materials available to him.

Formula 21

Light-duty Household Liquid Detergent

LAS (SO3 sulphonate)	10
Triethanolamine	2
Caustic Soda (45% solution)	1.7
Sodium hypochlorite (10% solution)	0.6
Lauric acid diethanolamide	1
Sodium sulphate	1
Water	83.7

An opaque lotion type of liquid can be made (taking into account the same factors as mentioned above) from Formula 22.

Formula 22

Lotion-type Light-duty Liquid Detergent

LAS	19.5
Monoethanolamine	4
Lauric acid monoethanolamide	1.5
Sodium hypochlorite (10% solution)	0.6
Sodium sulphate	0.9
Water	73.5

In this case the dodecyl benzene sulphonic acid, the sodium sulphate and the water are mixed in the neutralization vessel, the sodium hypochlorite added and mixing continued for at least 20 min. The lauric acid monoethanolamide, being solid, is best dissolved in the monoethanolamine with heating. The mixture of the two is then added to the vessel, after the bleaching has if necessary been completed. If an opaque solution is required an opacifier can be added. The product can now be dyed and perfumed.

To manufacture a liquid from an alkyl benzene sulphonate neutralized only with caustic soda ( in practice, a concentrated paste of the sodium sulphonate is used as the starting material), a low cloud point can be achieved by the addition of urea. With the sodium sulphonate however, urea lowers the viscosity considerably. Addition of a fatty acid dialkylolamide will restore the viscosity.

Modern tendencies are to use both stronger solutions and mixtures of active matter. One of the main uses for light-duty liquid detergents is hand dishwashing, and for this particular application foam is important other than from the point of view of sales appeal. Grease released from the dishes floats to the top of the washing solution and forms an oily film which can be redeposited on the plate when it is withdrawn from the sink after having been washed. Due to the enormous surface area in a foam, this grease is held in a thin, easily rinsable film on the bubbles, preventing redeposition. When the foam collapses due to saturation with oil, the solution is considered to be exhausted and methods of test for the efficiency of dishwashing liquids are based on this foam collapse.

Ether sulphates, both of the alcohol and alkyl phenol types are finding more and more use as constituents of dishwashing liquids. If the ammonium salt of the alkyl phenol type is used care must be taken not to raise the pH of the final liquid over 8 or otherwise a smell of ammonia will appear. If a high pH is desired without the ammonia smell, the ammonium ether sulphates can be heated with a stoichiometric amount of caustic soda until the ammonia is distilled off. Alternatively an 'ammoniated' cleaner, which has some sales appeal, can be made at the high pH.

The choice of the type of ether sulphate is rather wide, as the base material can be any one of the alcohols available on the market or any of the alkyl phenols and then again the amount of ethylene oxide can be varied from between 1.7-4 molecules per molecule. Gohlke and Bergerhausen have investigated viscosity and foam height with different alcohols and different degrees of ethoxylation. They have come to the conclusion that the best foamers are a C12-14 alcohol with 2 molecules of ethylene oxide. Another important fact in the make-up of the ether sulphate is the amount of polyethylene glycol present. The authors have found that relatively large (of the order of 3 per cent) amounts of polyethylene glycol can act as a solvent of 'thinner' on the final sulphate to reduce the viscosity of the solution.

As the wetting properties of either sulphates are low they are not recommended as dishwashing agents alone, rather in conjunction with non-ionic or other anionic detergents.

Alcohol, sulphates, neutralized with ethanolamines can, of course, be used alone, or with an alkylolamide as a foam booster. It is interesting to note that alkylolamide have no effect on the foaming properties of ether sulphates. Some typical basic formulations are given in formulae 23-27.

Formulae 23-27

Light-duty Liquid Detergents

<td colspan='3' align='center'>to make 100

	23	24	25	26	27
LAS (SO3 sulphonated)	10	15	20	12	-
Caustic soda (40% solution)	3.2	3.2	3.2	3.2	-
Triethanolamine	-	2.2	4.4	9	-
Sodium alcohol ether sulphate (100% basis)	-	3	3	-	-
Ethanolamine alcohol sulphate (100% basis)	-	-	-	-	24
Coconut diethanolamide*	2	1	1	-	2
Sodium sulphate or chloride	qs	qs	qs	qs	qs
Dye, perfume	qs	qs	qs	qs	qs
Water

It will be observed that the first and fourth formulation are relatively cheap, the others more sophisticated.

SO3 sulphonated LAS can be considered the work-horse of liquid detergent formulations. It is good practice, when mixtures of LAS with alcohol or ether sulphates are used to ensure that the LAS is neutralized completely before the sulphate is introduced into the reactor. This will eliminate hydrolysis of the acid-unstable sulphates. To facilitate formulation the following data show the alkali requirement of a typical LAS.

100 kg LAS requires for complete neutralization :

12.8 kg NaOH (100%)

18.8 kg KOH (100%)

45.5 kg Triethanolamine

33.6 kg Diethanolamine

19.7 kg Monoethanolamine

The inorganic salts are included only if it is desired to increase the viscosity. The diethanolamide acts as a viscosity booster but particularly where the ether sulphates are included coconut monoethanolamide will be more effective. To incorporate the monoethanolamide, the solution is merely warmed to 60°C with mixing, when all the monethanolamide will melt and dissolve and will not be thrown out of solution on cooling.

Household fine-wash detergents are, of course, not limited to liquids. They can be made as spray-dried powders, sometimes only with 20-30 per cent active matter and the balance sodium sulphate as the inert filler, but more often than not they include sodium tripolyphosphate, some silicate occasionally CMC, and an optical brightening agent, substantive to the fibres for which the powder is being used. The phosphate, of course, helps in the detergency, and the silicate acts in this case as a corrosion inhibitor. Here, the action of the CMC is not as pronounced as it is on cottons, but on woollen fabrics it does aid in preventing redeposition, and as these powders are meant for hand-washing, it does tend to give a protective colloidal action on the skin.

A powder of this type can be manufactured as detailed in Formula 28.

Formula 28

Household Fine-wash Spray-dried Powder

	Minimum	Maximum
Sodium alkyl benzene sulphonate	10	25
Sodium tripolyphosphate	15	25
Sodium silicate (preferably 1 : 3 ratio) anhydrous	3	5
CMC (100%)	0	1
Lauric acid monethanolamide	0	2.5
Optical brightening agent	0.2	0.2
Sodium sulphate		Balance

By virtue of the nature of manufacture, fine-wash powders of this type can not be made by the absorption methods, as the surplus of soda ash will prove detrimental to the operation of the powder. However, a dry mixed type of powder can easily be made to Formula 28, using as a base a concentrated powder of about 60 per cent active matter.

In certain parts of the world, neutral pastes of sodium alkyl benzene sulphonate are sold also for fine-wash purposes. These pastes very in concentration between 20 per cent and 50 per cent active matter. The consistency of the paste varies with the ingredients and the method of manufacture of the alkyl benzene sulphonic acid. Stiffer pastes are obtained with tridecyl benzene sulphonic acid, sulphonated with oleum; and the softest paste is linear dodecyl benzene sulphonic acid, sulphonated with SO3 gas.

The alkyl benzene sulphonates have limited solubility in water. They, however, can absorb water to form a natural paste. If the amount of water present is above that which can naturally be absorbed, the mass will separate into two phases on standing : a concentrated phase of alkyl benzene sulphonate on top and a weak solution of alkyl benzene sulphonate and inorganic salts at the bottom. The concentration of the sodium alkyl benzene sulphonate in the upper phase varies with the material, but is of the order of 55 per cent active matter. This means that pastes of 55 per cent can be manufactured with no special additions. If lower concentrations are required, it is necessary to add certain ingredients to prevent this separation. Materials that can be used : are hydrotropes, which will make the final paste thinner in consistency, so that stiffening materials have again to be added; alkylolamides, which have the added advantages of foam boosting and skin protection (these pastes are to be used by hand); and CMC. Both the CMC and the alkylolamides tend to increase the viscosity of the mass in such a way that separation cannot take place.

If only CMC is used as the thickening agent, a general rule is to manufacture the paste to a 55 per cent concentration and then to add sufficient of a 10 per cent CMC solution in water to bring the concentration down to he required amount. Sodium sulphate is then added to increase the consistency.

A 40 per cent active paste, using both conventional dodecyl benzene and linear dodecyl benzene sulphonic acids, both sulphonated by SO3 gas, is given in Formula 29.

Formula 29

40 per cent Detergent Paste

ABS (100%)	40
Caustic soda (45% solution)	11.4
Sodium sulphate	2
Sodium hypochlorite solution	0.6
Water	29.3
CMC	1.7
Water	15

This paste may be reduced to 30 per cent by increasing CMC to 2.5 or 3.5 per cent and adding water.

General-Purpose Detergents

Powders of this type are the most popular for household use. They are not harshly alkaline, and contained relatively large quantities of both active matter and sodium tripolyphosphate. These achieve the action on cottons without the addition of further alkalies, and the alkalinity naturally present from the phosphate does not harm delicate fabrics.

By virtue of their formulation these powders are truly general-purposes and can be used for virtually every household job. They suffer from the disadvantage, however, of being unsuitable for fully automatic household washing machines, as, in general, they foam too much.

A generally accepted formula for this type of powder to be manufactured by a spray-drier is given in Formula 30.

Formula 30

Spray-dried General-purpose Powder

Active matter as alkyl benzene sulphonic acid	25
neutralized with caustic soda Sodium toluene sulphonate*	2.5
Lauric monethanolamide	3
Sodium tripolyphosphate	30
Sodium silicate (1:2 ratio) anhydrous	10
CMC (100% basis)	2
Optical brightening agent	0.2
Sodium sulphate	27.3

The addition of 10 per cent sodium perborate is, in our opinion, advisable, but again is dependent on washing practices in the particular country. As a guide, in the United Kingdom, powders of this sort have at least 8 per cent sodium perborate added, and in most of Europe even more.

If sodium perborate is to be added, we suggest that 2 per cent of the sodium sulphate be replaced by magnesium sulphate on any anhydrous basis. This magnesium sulphate is added to the slurry prior to spray drying.

A general-purpose powder can be made by the absorption and mixing process as well, but in this case, due to the limitations of the process, the active matter is limited. The formulation suggestion is give in Formula 31.

Formula 31

General-purpose Powder

Dodecyl benzene sulphonic acid	18
Sodium tripolyphosphate	25
Sodium silicate (1:2 ratio) 40% solution	5
CMC (100% basis)	5
Sodium bicarbonate	28
Soda ash	20
Optical brightening agent	0.15
Water (or sodium hypochlorite solution)	2

As in Formula 31, the same remarks apply regarding the addition of sodium perborate. If this is to be introduced, it is suggested; that the sodium bicarbonate be lowered to 25 per cent and 3 per cent magnesium sulphate crystals added. If sodium hypochlorite is used to bleach the powder and if sodium perborate is to be incorporated, the precautions as detailed must be observed.

A general-purpose powder can be manufactured by dry-mixing according to Formula 32.

Formula 32

General-purpose Powder

60% alkyl benzene sulphonate powder containing silicate	45
Sodium tripolyphosphate	30
CMC (100% basis)	2
Optical brightening agent	0.2
Sodium sulpahte	22.8

Here, if sodium perborate is to be used, no special precautions need to be taken and it can, of course, be added initially with all the other ingredients.

In all the formulations given hitherto, we have included relatively large amounts of sodium tripolyphosphate, this despite the fact that in certain countries there is a complete of partial ban on the use of phosphates. To date no 'plug-in' replacement for this excellent builder has been developed. Where this is a partial ban, the above formulations to include STP up to the limit allowed and to add a zeolite to make up the differences is suggested. Where there is a total ban, the available alternatives must be considered; increasing the silicate, use of NTA, use of zeolite (the zeolite/silicate co-crystal mentioned might be eminently suitable), or one of the polymers specially mooted for this purpose. The final formulation will probably be a combination of any two or more of the above.

For fully automatic, front-loading household washing machines, foam control needs to be applied. This can be by the use of soap as for heavy duty powders, but infinitely better performance will be attained if the ternary mixture of the anionic/non-ionic/soap is used as described. With the new processes and mixing equipment for the inclusion of non-ionics into powders, there need be no practical limits to the formulation.

Choice of Non-Ionic

As can be appreciated from the description of the possible non-ionic surfactants, the choice is wide and often confusing. Much work has been done on the optimization of the molecule. Cox and Matson have compared various molecules for their cleaning efficiency in hard-surface cleaning. Kravetz has done the same for soil removal on cloth. It is true that the results cannot be compared directly because of the different substrates, but the results are revealing.

Their results can be summarized :

1. From Cox and Matson's work on hard-surface cleaning it appears that linear alcohols with a low molecular weight and containing 50 per cent ethylene oxide (average chain length 8.6 carbons with 3.1 moles EO) in a relatively high concentration (5 per cent), are better in cleaning efficiency for grease, wax and particulate soil than the molecules containing C10 and higher chain lengths with the appropriate amount of the ethylene oxide to maintain the balance. [p align="justify"]This was explained by the fact that the low-molecular-weight hydrophobe acts as a solvent and this was confirmed by adding a glycol ether when no improvement of soil removal was noted.
2. For low dilutions of the surfactant the optimum chain length was shifted to the C8-10 range. Under these conditions of dilution the hydrophobe can no longer act as a solvent and performance was dependent solely on the surface active effect.
3. Comparison of the low carbon number ethoxylated alcohols with a built formulation containing nonyl phenol with 9½ EO units again showed a better performance for the low-molecule weight alcohol ethoxylates.
4. Kravetz compared the performance of a linear primary alcohol ethoxylate, a linear secondary alcohol ethoxylate, both of approximately C13 average chain length, and a branched octyl phenol ethoxylate, each with varying amounts of ethylene oxide and for both cotton and cotton/ polyester blends.
5. The results show that 7-9 EO units one each give optimum performance for Sebum, oil and clay removal on the blend but for sebum removal from pure cotton 12-15 EO was superior.

Further work by Rosen confirms the above in that he found that short-chain non-ionics are better in removing water repellent soils.

The above facts and figures do not take into accounts the added complications of the presence of anionic detergents and builders but they do indicate a trend.

From the above it appears that any of the commercially available non-ionic types with approximately 8 EO units will give good all round performance. For powders, for technological consideration, the choice of non-ionic has been in somewhat higher register hitherto.

With the development of system for incorporation of non-ionics into powders without spray-drying the problem associated with making powders using these (relatively) low-molecular-weight materials no longer apply.

The use of this type of non-ionic in liquids will tend to give a low cloud point but this can be overcome by the judicious use of co-solvents and hydrotropes.

The term cloud point can be somewhat confusing. Normally it is the temperature at which a cloud forms on cooling. This demonstrates the lowest temperature at which a liquid can be stored and still remain clear. When applied to non-ionic solutions it indicates the temperature at which the solution becomes cloudy on heating, at this temperature the solution separates into two phases, one of which will be richer in non-ionic than the other.

Concentrated Powders

A new approach to the manufacture of powders is what is called the ½ or ¼ cup concentrates, where a minimum of inert filler, if any at all, is used. A patent by Colgate describes the technology for the production of these powders.

In brief the process is to mix STP with water and sodium silicate in a crutcher to allow the STP to hydrate to its hexahydrate, then to added a further quantity of STP and water under conditions that this second addition does not hydrate and to spray-dry the mix. To the spray-dried beads non-ionic detergent is added in a special mixer.

The details are :

Mix together

STP	14.5
Sodium silicate (1:2.4 ratio, 50% solution)	15.2
Deionized water	21.0

Maintain the slurry at 60°C for hydration and then raise the temperature to approximately 90°C, add

STP	28.3
Deionized water	21.0

At this higher temperature no hydration takes place, this slurry is then spray-dried to a bead containing 10% moisture, with a bulk density of ± 0.55 g/ml.

The finished beads are then sprayed, either continuously or batch-wise with a non-ionic, of the alcohol ethoxylate type mixed with minor ingredients; optical brighteners, dye, perfume, etc. The post-mixer mentioned in the patent is one of the Patterson-Kelley types but it is conceivable that any of the mixers described can be used. The finished powder has a bulk density of 0.68 g/ml and contains.

Base bead	78.0
Non-ionic	19.7
Minor ingredients	2.3

The granules are attractive and dustless and a further claim by the patentors is that they are sufficiently pourable to be packed in a transparent specially designed bottle.

Further embodiments of the patent include adding fillers other than STP to the hydrated STP. No mentioned of the inclusion of CMC is made but it is envisaged that it could quite easily be added to the slurry prior to spray drying.

Cold Water Washing

A generation or so ago all washing was done at the boil or near it. With the advent of synthetic fibres wash temperatures came down drastically and now in an attempt at energy conservation householders are beginning to use cold water only, for washing of clothes.

The industry is facing and meeting the challenge, and a challenge it is because the highly complicated washing processed requires, among other things, energy to break the bond of the dirt to the substrate. This energy can come from lowering of the interfacial tension, the mechanical energy imparted by the motor of the machine and from heat.

For cold washing the thermal energy needs to be replaced, and one method is by increasing the amount of active matter in solution and using more non-ionics which are better for soil removal from synthetics. Zweig and her co-workers have studied the parameters involved in cold washing with non-ionics and have come up with some surprising and novel findings. The conclusions can be summarized:

1. Non-polar soils are difficult to remove from polyester/cotton fabrics at low temperatures, thus the inherent detergency needs to be enhanced.
2. Optimum detergency for this system is found with non-ionic mixtures which have cloud points in the range of 15-25°C below the wash temperature. This is explained by the fact that a surfactant-rich pseudo-phase separates at temperatures above the cloud point. This can be considered to be globules of concentrated surfactant which are attracted to the soil (note also the remarks of Rosen).
3. Low cloud points were obtained by blending lightly ethoxylated alcohol or unethoxylated alcohol with a normal detergent non-ionic.

In figures, a blend of 3 mol ethoxylated alcohol with an 8 mol non-ionic to give a cloud point close to 0°C enhanced the mineral oil detergency of the 8 mol alcohol ethoxylate by 50 per cent and a blend of a 9 mol non-ionic with decanol, again to give a cloud point close to zero enhanced the detergency of the alcohol-9 ethoxylate by 20 per cent.

These are the bare figures, but as the authors state there is a window through which efficient detergent systems for cold water washing can be seen. The technological problems of formulating these low cloud point non-ionics into liquid detergents need to be investigated.

As can be seen from the foregoing, possibilities of formulating are varied and later in this chapter we also discuss solvent powder detergents. The actual formulations to be used depend on many factors, mainly the materials easily available and the trends in the area where the powder be sold. The above statement also holds good for liquids.

To sum up we give in Tables 2 and 3 formulations which can be as starting points for the manufacture of both dry-mixed and spray-dried powders. These formulations do not necessarily parallel those already described in the text, but do give an indication of what is being made.

Table 2: Typical Formulations for Powders Produced by Dry Neutralization

-

All purpose non-machine	All purpose machine	Light-duty hand	Heavy-duty non-machine	Heavy duty machine	Solvent powder
LAS	14-15	5	15	12-15	5	5
Distilled-fatty acids	-	4	-	4	3
Non-ionic	2-3	6	2	-	4	3
STP	30	30	20	15	20	20
Metasilicate (5H2O) or spray-dried disilicate	3	3	-	5-6	5-6	5
Soda ash	15-20	15-20	20 max	to 100	to 100	to 100
Sodium bicarbonate	-	-	30	-	-	-
Sodium sulphate	to 100	to 100	to 100	-	-	-
CMC	2	2	-	1.5	1.5	1.5
Optical brightener	0.2	0.2	0.2	0.2	0.2	0.2
Perborate	10	10	-	10	10	-
Enzymes as 300,000 DU	-	0.5	-	0.5	-	-
Perfume	qs	qs	qs	qs	qs	qs
NaOH (30% solution)	2-3	2-3	2-3	2-3	2-3	2-3
Solvent deodorized kerosine	-	-	-	-	-	4

Table 3 : Typical Formulae for Powders Produced by Spray-drying

Heavy-duty hand	All-purpose Cold Water hand	Heavy-duty Machine	Light-duty hand
LAS (Na salt)	12	16	6	18
Non-ionic	3	4	4	2
Soap or distilled fatty acids	-	-	6	-
CMC	2	3	2	2
Sodium silicate 1:2.45 ratio (100% basis)	3	3	4	-
Soda ash	10	10	-	-
STP	30	35	30	15
MgSO4	1.5	-	1.5	-
Optical brightener	0.15	0.15	0.15	0.15
Na2SO4	22	28	30	60.1
Perborate	15	-	15	-
Sodium toluene sulphonate	1	1	1	1
Perfume	qs	qs	qs	qs
Enzymes	-	-	0.5-0.8	-
Residual moisture (approx).	10	5	10	5

Notes

1. Part of all of the LAS can be replaced by sulphonated methyl esters.
2. Perfumes for this type of powder should be of low volatility and added after spray dried.
3. All the above formulation lend themselves to production by the combined system described.

Hard-Surface Cleaners

A new development in both the household and the institutional cleaners field is the all-purpose liquid meant specifically for hard-surface cleaners-by hard surfaces are meant those surfaces that cannot be immersed in a bath or basin for cleaning, and the operation needs to be done in situ. These cleaners are usually liquid, alkaline and often contains solvents. Their purpose is to clean grease, mud, and atmospheric grime from walls, doors, glass, tiles, etc. Alkalinity can be derived from alkaline salts, or ammonia (occasionally caustic soda or potash) can be added. The solvent is added because it has been found that oil stains, although theoretically saponifiable by the alkali, cannot always be removed without it. This solvent needs to be soluble in water (unless an emulsion is to be made), reasonably odourles, non-toxic, with a fairly high flash-point and last but not least, a good fat solvent. The glycol ethers, in particular ethylene glycol monobutyl ether or dipropylene glycol methyl ether answer to all the above requirements admirably. Silicates are added both to buffer the alkalinity and to minimize corrosion on metallic surfaces. A typical formulation is :

Formula 33

Hard-surface Cleaner

Sodium alkyl benzene sulphonate (100% basis)	15
EDTA sodium salt	4
Ammonia (100% basis) (optional)	5
Butyl cellosolve	7
Sodium silicate (1:2 ratio, 100% basis)	3
Water	to 100

it goes without saying that if ammonia is to be added the solution cannot be used on copper surfaces.

A generalized formulation which is becoming popular in household use is :

Syndet	5-8 wt%
Hydrotrope	6
Alkali	5
Dipropylene glycol methyl ether	4
pine oil	2
Water	Balance

The syndet can be non-foaming (non-ionic) or medium foaming (LAS) or high foaming (mixture of LAS and ether sulphate). The alkali can be ammonia, trisodium phospahte, tetrasodium pyrophosphate or sodium silicate, or one of the organic amines such as monoethanolamine. If organic alkine salts are not used the hydrotrope can be dispensed with. It is necessary to use softened water for this formulation as otherwise the hardness salts with precipitate or form a haze due to the high pH.

A particular instance of hard-surface cleaning is the oven cleaner. The above formula will theoretically clean ovens, but as grease is normally heavily encrusted on the surfaces of ovens more alkalinity than that provided in this formula is needed. A typical formula could be :

Formula 34

Hard-surface Cleaner

[/

Alkyl benzene sulphonate, sodium salt	4
Phosphoric acid (85%)	4.5
Caustic potash (100%) or monoethanolamine	9
Tetrapotassium pyrophosphate	4.5
Ethylene glycol monobutyl ether	6
Isopropyl alcohol	2
Sodium silicate 1:2 ratio (100%)	2
Water	68

It will be noted that the amount of caustic potash suggested is in excess of that required to neutralize the phosphoric acid, the surplus is needed to provide alkalinity. In the above formula the glycol ether is not completely soluble but the isopropyl alcohol acts as a coupling agent. Contrary to general belief, isopropyl alcohol is in itself a good fat solvent.

For certain institutional purposes it might be necessary or desirable to produce an oven cleaner as a paste or viscous liquid so that it will not drain down vertical surfaces. Formulae 34 and 35 can be modified by addition of either a thickening agent or colloidal silica. If a viscous liquid is to be made it can be conveniently packed as an aerosol. Vanderbilt Corporation suggests the following formula for an aerosol oven cleaner :

Formula 35

Aerosol Oven Cleaner

Veegum-T*	1.5
Ammonia solution	6
1,1,1-Trichlorethane	18
Water	24
Ethanol	7.5
Tergitol NPX†	18
Propellant :
Dichlorodifluoromethane	17.5
Dichlorotetrafluoroethane	7.5

* Vanderbilt Corporation.

† Union Carbide.

A low temperature oven cleaner has been described in a patent where mannitol or sorbitol is used for alcoholysis of the fat deposited, with sodium or potassium bicarbonate as the alcoholysis catalyst and salts of low molecular weight organic acids to esterify the alcoholysis product. The formulation could be :

Sorbitol	2-5
Potassium	0.1-4.0
Eutectic mixture of Sodium acetate Lithium acetate	1-5
Potassium acetate Thickener	qs
Precipitated chalk	20-30
Wetting agent	qs

The eutectic mixture is to lower the melting point of the salts to allow them to react easily. Other salts recommended could be sodium tartrate. Rochelle salt or sodium glycolate.

Machine Dishwashing

Until a few years ago household dishwashing was done by using one of the fine-wash or general purpose formulations mentioned above. Of recent years the household dishwashing machine has come into popular use and this has requirements of its own. The mechanical cleaning action is done by means of jets of water. These jets are produced by a high-pressure pump or by the whipping action of a fast revolving propeller. In either case it is essential to the operation of the machine that the detergent added be completely non-foaming (and not even with a 'controlled foam' as in household laundry).

Non-ionics, in general, foam considerably less than anionics, but even they do foam slightly, so the amount of detergent is therefore kept to a minimum and the cleaning effect is achieved by the use of alkalis and phosphates. Almost completely non-foaming non-ionics have now been developed by blocking the terminal-OH group. One of the common methods is to add a methyl group to the terminal-OH, if, for example, a non-ionic is to be made by the esterification of polyethylene glycol and a fatty acid, instead of the polyethylene glycol a methoxy-polyethylene glycol is used. Another method is to condense to the finished non-ionic detergent a further molecule of butylene oxide. The formulation also depends to a very great extent on the type of water being used. Household water-softeners are only now beginning to appear on the market; so the formula must take into account whether the water being used is soft, moderately hard or hard.

For soft-water areas, soda ash, besides being cheap, can provide a portion of the alkalinity, but in moderately hard and hard water the soda ash will leave a scum of calcium carbonate on crockery and cutlery.

For moderately hard water tetrasodium pyrophosphate can be used to give both detergency and alkalinity, but for hard water sodium tripolyphosphate in combination with strong alkalis must be employed.

Most dishwashing machines have a drying cycle as well as the rinsing cycles, or at least dishes are left hot and the last traces of moisture on them dry very quickly on contact with the air. It is, therefore necessary to provide for the last traces of water to drain from the dishes in a uniform film to avoid water spots particularly on glassware.

This effect can be achieved by incorporating solvents or an organic chlorine-releasing compound into the powder. Chlorine-releasing materials react with non-ionic detergents and it has been found by the authors that these powders work very successfully without any detergent at all. If, however, it is desired to incorporate a detergent, a very small amount of non-ionic detergent can be used. FMC has suggested a method whereby non-ionic detergents can be incorporated into these powders in the presence of chlorine releasing agents. It recommends the low-foam modified non-ionic detergents mentioned above. This detergent, at the rate of 1-2 per cent based on the final weight, is pre-mixed with the most alkaline ingredient present (anhydrous metasilicate), the tripolyphosphate added next and then the other ingredients and finally the chlorine releasing compound.

Highly alkaline materials such as metasilicate can affect the over-glaze on delicate china and cause 'crazing' of the glaze. This can be eliminated by the incorporation of boric acid (not more than 5 per cent), sodium aluminate (2 per cent) or zinc salts in the formula.

Since these powders usually contain large amounts of sodium metasilicate, they are not normally made by spray-drying, as there is a limit to the amount of sodium metasilicate (which is hygroscopic) which can be incorporated into a spray-dried powder. They are produced instead, by a mixing and absorption technique.

To make these powders dustless, granulation techniques are used. The powders and the non-ionic detergent are mixed as described above, without the chlorine-releasing material. On to this mixture a small amount of waterglass is sprayed in a mixer with a revolving to tumbling action, when the waterglass glues the particles together and the revolving action gives them a spherical shape. The chlorine-containing material is then added.

A formula suitable for use in soft-water areas is given in Formula 36.

Formula 36

Machine Dish-washing Powder for Soft-water Areas

Tetrasodium pyrophosphate	49
Sodium metasilicate anhydrous	25
Soda ash	22.5
Sodium dichloro-iso-cyanurate (60% available chlorine)	1.5-4.5
Non-ionic detergent, eg, nonyl-phenol 9 mol ethox	2

This formulation is also suitable for dishwashing machines used in catering establishments.

Because of the small amount of detergent involved, it is not necessary to use any special procedure for the incorporation of the active matter. The easiest method is to blend in with the other powders a concentrated detergent powder. Alternatively, any other already prepared detergents powder can be used as the source of the active matter and due allowance must then be made for the other ingredients in this powder.

Where the water is moderately hard the product should be made according to Formula 37.

Formula 37

Machine Dish-washing Powder for Moderately Hard-water Areas

Tetrasodium pyrophosphates	60
Sodium metasilicate anhydrous	38
Trichloro-iso-cyanuric acid	1-3.5
Non-ionic detergent	1

For very hard water areas the following formulation will be suitable :

Formula 38

Machine Dish-washing Powder for Hard-Water Areas

Sodium tripolyphosphate	50
Sodium metasilicate pentahydrate	25
Trisodium phosphate anhydrous	15
Non-ionic detergent	3
Hexylene glycol	2
Isopropyl alcohol	1.5
Water	3.5

The liquids are pre-mixed and then the powders are charged into the mixer and the liquid sprayed on to the powders while mixing.

For institutional machine dishwashing the tendency is to move away from powders to liquids as these can be done either continuously or in accordance with pre-set requirements based on electronic controls.

Liquid for dishwashing machines can be formulated with either a non-ionic component or active chlorine, but not both.

Alkalinity is obtained from caustic alkali (soda or potash) with the addition of the corresponding silicate, together with a condensed phosphate. The same problem of common ion effect occur as described for HDLD, thus a basic formula could be :

Tetrapotassium pyrophosphate	15
Potassium silicate (1:2 mol ratio, 40% solution)	8
Potassium hydroxide (45%)	10
Soft water	67

Potassium tripolyphosphate, if available, would obviously give vastly improved performance.

To this solution is added a per cent of a non-foaming non-ionic or 2 per cent active chlorine. The chlorine in this instance can be added by direct injection of chlorine gas to form potassium hypochlorite in the solution.

Abrasive-Type Cleaners

The most popular household abrasive cleaners are scouring powders. These are usually dry mixes of all of the ingredients. A typical formulation is given in Formula 39.

Formula 39

Household Scouring Powder

Abrasive	87
Soda ash	5
60% concentrated detergent powder	8

If desired, this can also be manufactured from sulphonic acid by mixing together :

Abrasive (powder calcite or marble)	85
Soda ash	7
then adding in the mixer : 100% alkyl benzene sulphonic acid (ABS)	5
and water	3

If this scouring powder is to contain active chlorine, as is becoming the fashion now, it is advisable not to use soda ash, as concentrated organic-chlorine-releasing materials are not in general stable in the presence of soda ash, except for the potassium salt of trichloro-iso-cyanuric acid.

Alkalinity can be obtained by anhydrous sodium tripolyphosphate or tetrasodium pyrophosphate. To avoid introducing moisture into the powder, the active matter can best be put in by the use of an already made detergent powder, not necessarily a concentrated one. A chlorine containing powder is best packed in plastic containers.

A suggested formulation is Formula 40 which is a chlorine-containing household scouring powder.

Formula 40

Chlorine-containing Detergent Scouring Powder

Detergent powder containing 20% active matter (without soda ash)	15
Tetrasodium pyrophosphate	5
Abrasive	79
Trichloro-iso cyanuric acid	1

Where a spray-drier is being operated. Formula 40 is a useful outlet for the cyclone fines produced by the spray-drier. A scouring liquid can be made according to Formula 41.

Formula 41

Household Scouring Liquid

Disperse Bentonite	5
in water	25
Add 12% active ready-made liquid detergent and dissolve in the liquid :	35
Sodium metasilicate pentahydrate or water-glass	3
and then disperse in this solution Abrasive	32

Special suspending agents suitable for this type of product are now available. These prevent settling of the abrasives.

Miscellaneous Household Cleaners

Window cleaners of the gentle abrasive type, using whiting, were once popular. These have now been superseded by liquids like those of Formula 42.

Formula 42

Household Window-cleaning Liquid

Active detergent matter	0.25-0.5
Isopropyl alcohol	15-35
Water	to 100[[/TD]/tr]
Dye	as required

Similarly, for stone or tile floors, although materials such as that given in Formula 1 are used, liquid floor cleaners according to Formula 43 are now also being manufactured.

Formula 43

Floor Cleaner

I

Active detergent matter	2-5
sopropyl alcohol	8-15
Pine oil	1-2
Water	to 100

Commercial Laundering

In commercial laundering, powders are used which do not foam and which are in general more alkaline than household powders. Most commercial laundries use soft water, and we suggest to the detergent manufacturer that if he supplies washing powders to a laundry which does not use soft (or softened) water, he should make every effort to convince his customer that it is essential for him to use it.

Laundry powders can be made both by spray-drying and by absorption and neutralization. The two formulations below have been used with success in commercial laundries.

Formula 44

Spray-dried Industrial Laundry Powder

Alkyl benzene sulphonic acid	20} Neutralized with
Distilled tallow fatty acid	15} NaOH to sodium salts
Tetrasodium pyrophosphate	15
Sodium metasilicate	15
CMC (100% basis)	2
Optical brightening agent	0.15
Soda ash	33

Formula 45

Industrial Laundry Powder not Spray-dried

Alkyl benzene sulphonic acid	11
Distilled tallow fatty acid	7
Tetrasodium pyrophosphate	10
Sodium metasilicate pentahydrate	7
CMC (100% basis)	1.8
Optical brightening agent	0.1
Soda ash	61.1
Water	2

It is obvious that for a given load of washing more of Formula 45 will need to be used than of Formula 44.

Many laundries carry out a pre-wash at a lower temperature.* One of the above powders can be added to the pre-wash, but a more effective method is to use for the pre-wash a solvent detergent.

Solvent Detergents

It is not too difficult to combine non-ionics with solvents, but anionics are not easy to combine, especially those of the alkyl aryl sulphonate type, as most of these are insoluble, or only slightly soluble, in most non-polar solvents such as kerosene or deodorized kerosene which, of course, are generally the least expensive ones.

Detergents often serve only as emulsifying agents for the solvents, and not so much as detergents or cleaning agents. Emulsifiable insecticide concentrates, for example, are based on a solution of the emulsifying agent within the insecticide solvent mixture, forming a clear stable solution which, on dilution, gives a milky white emulsion with water. Here the emulsifying agent is a very often a non-ionic detergent acting as an emulsifier, rather than as a detergent proper. However, in this book, we are more concerned with solvent-detergent combination, in which the detergent acts both as an emulsifying agent for the solvent, and as a detergent in its own right.

In detergent-solvent combinations, the job of the solvent is to dissolve grease and similar oily dirt. The function of the detergent is to act as a penetrating and wetting agent and as an emulsifying agent for carrying off solvent after it has dissolved the oil or grease from the material to be cleaned, but it also keeps solid dirt particles in suspension. In many cleaning operations the detergent, by its surface activity alone, is simply not powerful enough to loosen dirt which is kept strongly attached to the surface by oily or resinous matter. This is very often encountered in metal-cleaning, or during the laundering of oil overalls. On the other hand, it is often impossible for a solvent alone to develop its full dissolving power where the oil matter is covered by solid crusts of insoluble matter. This is the case in the decarbonizing operations carried out on the working parts of internal combustion engines. It is the combination of surface activity plus solvent powder which makes solvent-detergents to useful in widely different fields of application.

The most easily produced type of solvent-detergent is a combination of non-ionic detergent with solvents. Very often a simple mixing of solvents with detergents is sufficient to obtain a clear, stable product, which generally forms milky emulsions in water. However, not all non-ionics are soluble in any proportion in any solvent. Very often they are only slightly soluble in non-polar solvents of the aliphatic type. Here it is necessary to use so-called 'co-solvents', together with the non-polar aliphatic solvent, to give the desired results.

The subject of solvency is of the greatest importance in working out effective products. By giving concrete examples, it will be made clear how important this type of solvent is in formulating high-grade products.

Generally speaking, the non-ionic detergents are more easily soluble in solvents than most anionic detergents. It is, nevertheless, quite incorrect to assume that they are soluble in all kinds of solvents. Thus, for example, a condensation product of nonyl phenol with 9-10 moles ethylene oxide is readily soluble in chlorinated solvents, xylene benzene, and in most polar solvents; it is, however, only slightly soluble in kerosene and white spirit and even less so in dearomatized (deodorized) kerosene. To increase the degreasing power of trichlorethylene, it is possible to add a certain percentage of non-ionic e.g. 3-5 per cent, to the solvent. Furthermore, a stable solution of trichlorethylene may be produced by dissolving 10-15 per cent of non-ionic in trichlorethylene. On dilution of the clear solution with water, a milky-white emulsion will be obtained. In order to prevent corrosion due to free hydrochloric acid, an addition of about 0.5 per cent monoethanolamine to the composition is advisable.

Chlorinated solvents should be used with cautions preferably they should be used in closed system, where the solvents is distilled, condensed and recycled, such as in dry cleaning and closed metal degreasing systems. The low heat of vaporization of these chlorinate solvents (210 J/g for perchlorethylene) and non-inflammability are distinct advantages.

As already pointed out, most non-ionic detergents are soluble in aromatic solvents and by dissolving 10 per cent in xylene and diluting the clear xylene solution with water, stable milky white emulsions may be obtained which are very useful for metal-degreasing compounds. Aromatic solvents may serve as co-solvents for dissolving non-ionic in aliphatic non-polar solvents such as dearomatized kerosene and white spirit. To obtain clear solution, a proportion of about 30-40 per cent of aromatic solvents is necessary, eg, 10 parts non-ionic; 30 parts aromatic solvent; 60 parts kerosene.

Formula 46

Detergent-solvent Combination

Nonyl phenol 9 EO	30 parts
Isopropanol	20 parts
Xylene	50 parts

Formula 47

Detergent-solvent Combination

Nonyl phenol 9 EO	30 parts
Methylethyketone	35parts
Deodorized kerosene	50 parts

Mix the materials in the order given. A clear solution is obtained which becomes blue-white opalescent when diluted with water (hard or soft). Nonyl phenol-9 ethox. behaves similarly to octyl phenol ethoxylates.

For the internal degreasing of motors, etc., such combinations with non-ionic detergents and solvents should prove very useful, possibly in combination with flushing oils. Even in the unlikely event of solvent-detergent remaining in the engine, practically no danger of subsequent corrosion should exist, because of the complete volatility of the products of combustion, which are hardly any more corrosive than the combustion products of motor fuels. It would even be possible to formulate an 'internal' decarbonizer on the basis of anionic detergents (AB sulphonic acid neutralized with alkanolamine of alkylamine), which does not leave any residues in the engine. Here again, an entire field for further research is open.

Another non-ionic detergent useful for formulating solvent-detergents is alkylolamide. Experiments with this compound (which is a condensation product of ethanolamine with fatty acids) have yielded very efficient solvent-detergents. However, the wetting power of alkylolamide is somewhat lower than that of water-soluble alkyl phenol of fatty alcohol ethoxylates.

A special solvent-detergent combination of interest is one which gives a clear solution of kerosene in water according to Formula 48.

Formula 48

Kerosene Water Solution

Coconut fatty acid diethanolamide	20
Kerosene	20
Water	20

On dilution with soft or hard water., all these products give very stable solvent emulsions of good detergent powder.

The alkyl benzene sulphonic acids can also be used as the basis of solvent-detergent combinations.

It is essential to start operations with the unneutralized sulphonic acid. SO3 sulphonated sulphonic acid, because they contain minimal amounts of inorganic acids, can quite easily be incorporated into these combinations, but oleum sulphonated dodecyl benzene, if treated as described below, can also be turned into an acceptable solvent-detergent.

Formula 49

Solvent detergent Combination

Mix together :
SO3 produced alkyl benzene sulphonic acid (ABS)	50 parts
Kerosene	50 parts
Aromatic solvent	25 parts
Then slowly add :
Caustic soda solution (38°Be)	17-18 parts
After cooling to about 50°C add:
Isopropanol	10 parts
Pine oil	2 parts

A clear liquid is obtained, which at low temperatures becomes gel-like.

A small amount of water from both the water of solution of the caustic soda and the water produced by neutralization, will be presented. If a completely anhydrous material is required, the lower amines, isopropyl or butyl, can be used for neutralization. Care should be exercised in their use as they are volatile, toxic and inflammable.