US3741911A - Phosphate-free detergent composition - Google Patents

Abstract

A DETERGENT COMPOSITION, PREFERABLY PHOSPHATE-FREE, IS BUILT USING CONVENTIONAL BUILDERS, OPTIONALLY INCLUDING AN ORGANIC SEQUESTERING AGENT, AND CONTAINS AS THE ACTIVE SYSTEM A COACERVATE SYSTEM CONTAINING AN ALKYL OR ALKYLARYL POLYOXYALKYLENE CARBOXYLIC ACID AND A NON-IONIC DETERGENT. THE COACERVATE SYSTEM IS SUITABLE FOR WASHING FABRICS AND FOR USE IN AUTOMATIC DISH WASHING MACHINES.

Description

United States Patent 3,741,911 PHOSPHATE-FREE DETERGENT COMPOSITION Hugh J. S. Shane, Guelph, Ontario, Canada, assignor to Hart Chemical Limited, Guelph, Ontario, Canada No Drawing. Continuation-impart of abandoned application Ser. No. 58,202, July 24, 1970. This application Dec. 21, 1970, Ser. No. 100,356

Int. Cl. Clld 1/06, 1/83, 3/10 US. Cl. 252-527 4 Claims ABSTRACT OF THE DISCLOSURE A detergent composition, preferably phosphate-free, is built using conventional builders, optionally including an organic sequestering agent, and contains as the active system a coacervate system containing an alkyl or alkylaryl polyoxyalkylene carboxylic acid and a non-ionic detergent. The coacervate system is suitable for washing fabrics and for use in automatic dish washing machines.

This is a continuation-in-part of application Ser. No. 58,202 filed July 24, 1970, now abandoned.

This invention relates to a detergent composition, more particularly to a heavy-duty househould detergent composition containing a particular active system and which is preferably phosphate-free.

Many detergent compositions have been formulated over the past 25 years and those sold commercially for household use have employed as the active system mainly anionic surfactants, typically alkyl-aryl sulphonates and long-chain alcohol sulphates.

In accordance with the present invention, the active system is provided by a coacervate consisting of two essentially non-ionic surfactants. The members of the coacervate active system are an alkyl or alkyl-aryl polyoxyalkylene carboxylic acid or derivative thereof and a different non-ionic surfactant.

The alkyl or alkyl-aryl polyoxyalkylene carboxylic acids may be represented by the formula:

L 2 B4 -|n R2 R4 LRa Jm where R is a long chain alkyl radical or long chain alkylaryl radical, R R R R R and R are each hydrogen or a lower alkyl radical and may be the same or different, m is a small integer and n is a number.

Typically R is a long straight chain alkyl group containing from 8 to 30 carbon atoms, particularly 8 to 18 carbon atoms and more particularly from 12 to 18 carbon atoms. R also may be a branched chain alkyl group, such as a tridecyl group. In addition, R may be an alkyl phenyl group in which the alkyl group is an octyl, nonyl, or dodecyl group. Mixtures of compounds having different R groups may be employed.

R R R and R are usually each hydrogen, although one or more of such groups may be lower alkyl groups, such as methyl or ethyl. It is possible that the alkyleneoxy chains include units in which some of the carbon atoms have alkyl groups attached thereto and some solely hydrogen. Such chains may include blocks in which each unit has at least one of the carbon atoms substituted by an alkyl group and blocks in which each unit has unsubstituted carbon atoms. Alternatively, such chains may include the above-described units in random order.

n may have an average value which is a Whole number but need not be. A typical range of average values of n is 1 to 9, with about 3.5 to 7.5 being preferred.

R and R are usually hydrogen, although each may be a lower alkyl group, such as methyl or ethyl. m gen- 3,741,911 Patented June 26, 1973 erally is 1, although it may be another small integer, generally not exceeding 3.

Such alkyl and alkyl-aryl polyoxyalkylene carboxylic acids may be formed by alkoxylation of the corresponding long chain alkanol or alkyl-arylol, such as by ethylene oxide, propylene oxide or mixtures thereof used simultaneously or sequentially, followed by carboxylation of the resulting alcohol. Alkylene oxides other than ethylene oxide or propylene oxide, for example, butylene oxide, may be employed, but it is preferred to employ these materials.

Particular preferred alkyl polyoxyalkylene carboxylic acids are those formed by ethoxylation of a C to C long chain alkanol with from 4.5 to 8.5 moles of ethylene oxide. Ethoxylation is a well known and well described process and need not be further described. The resulting alkyl polyoxyalkylene alcohols, which are themselves nonionic surfactants and may be used as the non-ionic surfactant part of the coacervate system, are converted to a sodium salt of a carboxylic acid of the above formula by the Williamson synthesis, involving reaction with a halocarboxylic acid, usually monochloracetic acid, generally in the presence of sodium hydroxide or metallic sodium. The free acid may be recovered from the sodium or other alkali metal salt by neutralization.

The alkyl or alkyl-aryl polyoxyalkylene carboxylic acids may be used as the free acid in the formulations or in the form of salts, such as an amine salt, for example, with monoethanolamine or an alkali metal salt, for example, the sodium salt. These materials frequently are liquid in the free acid form and often solids in the alkali metal salt form.

The other component of the active system is another non-ionic surfactant. One preferred form of this other component is the alkoxylated product of a long chain alkyl phenol. Such long chain alkyl groups generally contain more than 8 carbon atoms, typically the octyl, nonyl or dodecyl groups. The alkylated phenols may be formed by alkylation of the phenol with the corresponding olefins. Another preferred form of the second component is an alkoxylated long chain alkanol.

The alkoxylation generally is performed using ethylene oxide or propylene oxide. Such alkoxylation processes are well known and need not be further described. A typical non-ionic detergent used in the systems of the present invention is that formed by ethoxylation of octyl or nonyl phenol with from 3.5 to 15 moles of ethylene oxide.

The long chain alkanol may be straight or branched chain and typically contains from 8 to 30 carbon atoms, preferably from 12 to 18 carbon atoms. Ethoxylation with 3.5 to 15 moles of ethylene oxide yields a preferred prod uct.

A coacervate is a hydrophilic sol in which one liquid is dissolved or suspended in another. The coacervate active system used in the compositions of the invention consists generally of a homogeneous sol of the two components, although the sol may be heterogeneous. The system may be formulated by mixing together the alkyl or alkyl-aryl polyoxyalkylene carboxylic acid or salt thereof and the non-ionic detergent in the weight ratio of 6:1 to 1:6, particularly about 4: 1.

It has been found that the above-described coacervate active system has a detergency superior to the sum of the components of the system.

The active system may be formulated to provide heavyduty household washing detergents using additives-The resulting formulation may be in free-flowing solid form or liquid form, depending on the nature and quantity of the additives. Many additives have been commonly used in detergent formulations and many of these materials may be used in making formulations incorporating the present invention. Such additives may be alkalis and fillers, such as, phosphates, sulphates, silicates and carbonates, oxygen release compounds, soil suspension agents, optical brighteners, tarnish inhibitors, softeners, foam stabilizers and germicides.

The phosphates used in the formulation of household detergents generally have been mainly sodium tripolyphosphates and to a lesser extent tetrasodium pyrophosphate or mixtures thereof.

The phosphates used in the formulation of household detergents generally have been mainly sodium tripolyphosphates and to a lesser extent tetrasodium pyrophosphate or mixtures thereof. The phosphates have a number of effects, such as sequestering calcium or magnesium ions in the water, redissolving insoluble salts of these metals in the fabric washed, deflocculation of insoluble materials, such as clay, emnlsification of oils and peptization of solids. Commercially available heavy-duty household detergents contain up to 60% by weight of phosphates, generally around 40 to 50%.

The presence of phosphates in household detergents is alleged to be linked with the growth of algal blooms in water bodies. Such allegations have resulted in a search for suitable replacement materials. In at least one jurisdiction a complete ban on the presence of phosphates in detergents has been called for.

In the built compositions based on the active system disclosed above, phosphate materials may be present, but it is preferred to replace such phosphate by organic sequestering or chelating agents, for example, the sodium or other alkali metal salt of the acids, nitrilo triacetic acid (otherwise known as NTA), ethylene diamine tetracetic acid (otherwise known as EDTA), diethylene triamine pentacetic acid (known as DTPA), hydroxyethylene diamine triacetic acid (known as HETA) and hydroxyethylene amino diacetic acid (known as HEADA).

It also is possible in certain instances to omit such sequestering or chelating agents altogether and obtain a product having satisfactory detergent properties.

The quantity of organic chelating agent present in the composition depends to a large degree on the quantities of the other components present.

The sulphate used may be sodium sulphate. The sulphate mainly is present as an inert filler but may have some effect on the foaming and detergency properties of the final product, depending on the nature and quantities of the active materials present.

As mentioned above, another class of builders used are silicates. Silicates have the ability to soften water by the formation of precipitate which may be readily rinsed away. In addition, silicates are able to suspend soil in solution and prevent the redeposition of the soil on the cloth. In addition, silicates have a good buffering action. Lastly, silicates have the effect of inhibiting corrosion of steel and aluminum by the detergents or other materials present. Silicates therefore are very useful materials in the formulation. Sodium silicate has commonly been used, although potassium silicate has been employed.

Further materials added as builders are carbonates. The carbonates generally used are sodium carbonate or soda ash, sodium bicarbonate, sodium sesquicarbonate and potassium carbonate. These materials provide alkalinity and also soften water by precipitation of calcium and magnesium carbonates, at pHs above about 9. The final formulation, constituted in accordance with the invention, generally forms an aqueous solution having a pH of about 9 to 10.5 when in the standard concentration of 1 cup (150 gms.) in 10 gallons of water.

Oxygen-releasing compounds which may be present include sodium perborate. This material has a bleaching effect on the fibres and in addition adds to the alkalinity and buffering properties of the detergent. Other bleaching materials may be incorporated into the composition. It is common practice in North America to use chlorine water as a bleach separately from the detergent composition and hence these oxygen-releasing compounds often are omitted entirely.

While the active system removes soil from the surface of fibres, it is often necessary to include in the built detergent an anti-redeposition agent. The material almost universally employed for this purpose is carboxy-methyl cellulose (otherwise known as CMC). Commonly carboxy-methyl celluloses having an average degree of substitution (i.e. the number of carboxy-methyl groups added per glucose unit) between 0.4 and 0.6. The quantity of CMC present in the final composition is small, generally of the order of one-twelfth to one-tenth of the weight of active material. Other anti-redeposition agents include carboxyl-methyl-hydroxy-ethyl cellulose and polyvinyl pyrrolidone.

In order not only to clean the fabric washed but also to brighten the appearance of the fabric, optical brighteners commonly are included in detergent compositions and may be included in those of the present invention. The brighteners usually are dyestuffs which are absorbed by the fibres from the washing solution, but are not removed subsequently during rinsing. The dyestuffs convert ultraviolet light into visible light on the blue side of the spectrum, thereby complementing any yellowishness present in the fibre.

Foam stabilizers generally take the form of alkylolamides. While these materials have little or no detergent power they act as foam boosters and increase the detergency of the active ingredient synergistically. In addition, these materials act as skin-protecting agents, the emollient effect of the alkylolamides helping to overcome the skin defatting tendency of the detergents. Typical of i such materials are coconut monoethanolamide (otherwise known as CMEA), coconut diethanolamide and coconut monoisopropanolamide.

Other materials may be present in the compositions. For example, borax may be included as a buffering agent. In addition, borax may be used where water softening and detergent synergism are required at lower pH values when the high alkalinity of other builders may irritate the skin.

Recently a trend to include enzymes in detergent formulations has developed in the detergent industry. Such enzymes may be included in the formulations of the present invention. Enzymes remove stubborn protein stains from fabric, such as blood, perspiration and egg-yolk by splitting the protein molecules into amino-acids. Such enzymes require time to act and this involves pre-soaking the fabno prior to normal washing. :In addition, many enzymes are sensitive to phosphate materials and hence are commonly included in pre-soaking compositions separate from the normal washing composition. Some phosphate-resistant enzymes have been developed and are included in the normal detergent formulation. In the formulations of the present invention containing organic sequestering agents, such phosphate-sensitive enzymes may be included.

The built heavy-duty formulations of the present invention generally contain the coacervate system as the main active system. It may be possible in certain cases, generally in the interests of economy, to replace part of the coacervate system by an anionic surfactant, typically an alkyl aryl sulphonate such as dodecyl benzyl sulphonate, or a non-ionic detergent different from those forming the coacervate system.

The detergent compositions of this invention generally are in the form of a solid free-flowing powder. The incorporation of the coacervate active system into the additives to form the powder. A number of techniques have been devised by the detergent industry to enable liquid active materials to be incorporated into the remaining materials to provide a powder product.

There is a limit to the quantity of active material which may be incorporated into a powder, and this limit is dependent on the nature of the materials involved and on the method adopted.

The two methods which are preferred for the formulation of the powders are spray drying and drum drying. The coacervate is mixed with the required proportions of fillers, etc. usually omitting bleaches and optical brighteners which are blended later. This mixture then is spray dried. The spray drying process is used frequently in the detergent industry and its advantages and method of use are well known and need not be described further.

In the drum process, the mixture is heated on the rotating drum and the product generally is recovered in the form of flakes.

Other methods include simple absorption of the liquid coacervate onto the inorganic salts. This methods is somewhat limited in its application and is generally not employed.

It is also possible to mix previously dried coacervate with the other solid ingredients. In this instance, the coacervate is dried first and then mixed with the solids. This method again is limited in its application.

In the formation of the built detergent composition, it has been found desirable first to form the coacervate system and then blend the system with the remainder of the ingredients.

The detergent compositions of the present invention operate satisfactorily at temperatures above 65 F., and this may be employed as cold water detergents or in automatic or semiautomatic washing machines operating at elevated temperatures around 140 F. or higher.

In addition, the coacervate system may be used to formulate low to medium sudsing dish washing materials for automatic dish washing machines.

The present invention is further illustrated by the following examples:

EXAMPLE 1 The following are typical formulations of built heavyduty household detergent compositions incorporating a coacervate system as the main active material (all percentages are by Weight). These formulations are biodegradable.

formed from the coacervate system described in Example 1, four of which (9 to 12) contain no chelating agent, one of which (10) is low in alkali and one of which two (11 and 12) additionally contain a foam stabilizer. The numbers are in grams Weight.

Heavy-duty household detergent formulations in accordance with this invention were compared for washing efiiciency with six well-known brands of detergent, one including enzymes and the others not.'A number of different stains, namely oil strain, coffee stain and dirt stain were imparted to a sample of bleached and finished cotton fabric and a bleached and finished mixed 5 0'50 cotton-polyester blend fabric.

The samples each were washed in a top-loading automatic washing machine for 25 minutes at 140 F. in samples of water having 125 ppm. and 300 ppm. hardness using 150 g. of detergent. After washing, the fabric was rinsed and spin dried. Following tumbler drying, the fabric was subjected to reflectance measurements using a Zeiss Elrepho reflectometer against a standard magnesium oxide block at 457 mg on the visible spectrum under standard illuminant C (67 00 K.).

Cleaning efliciency is determined by the following formula:

Percent cleaning efliciency:

Reflectance of washed cloths-Reflectance of soiled cloths X Reflectance of clean cloths-Reflectance of soiled cloths TABLE I Coacervate 12.0 14. 0 8.0 12.0 14. 0 Hartopol AB-80 6.0 3. 5 6.0 Sodium sulphate. 42.7 29.4 33.2 42.7 29.4 Sodium silicate. 6. 0 12.0 12.0 6. 0 12. 0 NTA trisodium s 10. 0 10. 0 10.0 10.0 10. 0 Soda ash 22. 6 30. 0 30. 0 22. 5 30. 0 CMC 0. 53 0. 53 0. 53 0.53 0. 53 Nonionic 6. 0 3. 5 Tinopal RES 200 0.0231 0.0231 0. 0231 0.0231 0.0231 Tinopal DMS .1 0.279 0. 279 0. 279 0. 279 0. 279

Bor Caloo fluorMR new 7 1 The coacervate system used included (1) 013-15 alcohol ethoxylated with ethylene oxide attached to CHaCOOH and weight of ethylene oxide in the weight ratio 4:

Hartopoi AB-BO is a dodecylbenzylsulphonato.

6.5 moles of an octyl phenol ethoxyiated with 52% by 8 0M0 is carboxymethyl cellulose and the material employed is marketed under the name Carboxel D-435.

4 The non-ionic was one sold under the name Rexoi 25-1 and consisted of a nonyl phenol ethoxylated with 9.5 moles (Le. 62 to 64% by weight) of ethylene oxide.

5, 1 These materials are optical brighteners.

EXAMPLE 2 The following illustrates five further formulations vention identified as 13 is fonmulation 2 with 25 cos. of a 5.25% solution of sodium hypochlorite added thereto.)

TABLE III Formulations Standard products P.p.m. 2 8 913ABCDE F Oil stain;

, 68.6 71.7 .4 68.6 70.0 60.2 70.6 70.3 Cmmnsgg 23. 23.; 1 22.2 25.2 68.8 69.3 H 1. 1.4 66.5 64.0 cttn/plyester 300 50.0 58.8 .0 54.5 41.4 40.4 53.2 38.0 aiggf 125 74.5 74.0 75.8 70.8 76.2 77.0 78.8 77.5 55.0 84.0 92.8 72.2 5gb 66.1; 65.0 .0 .7 60.0 .0 75. 76.2 Cmmn/Pdyester 300 40.5 46.0 51.5 75.0 65.6 44.0 55.5 71.0 60.2 60.4

gglg 125 80.4 00.2 01.6 85.5 00.2 93.4 93.8 92.6

01.2 02.2 05.0 02.3 05.0 05.0 02.6 8.6 87.2 88.6 87.8 88.6 Cmwn/Pdyester 300 84.8 87.5 86.5 86.2 88.8 86.5 87.2 00.0 88.5 88.0

7 EXAMPLE 4 The foaming characteristics of the formulations 1 to 6 in Example 1 were tested as against those of the three commercially available detergents A, B and C referred to in Example 3.

An 0.3% concentrated solution in 125 ppm. hardness water was made up and shaken at 140 F. The volume of foam was measured initially and then after 5 minutes. The results are reproduced in the following Table IV:

TABLE IV min. mins.

EXAMPLE 5 The following are typical formulations of built heavyduty household detergent compositions incorporating two diiferent coacervate systems (all percentages are by weight) TAB LE V Coacervate:

1 Coacervate A includes (i) 013-15 alcohol ethoxylated with 5.5 moles of ethylene oxide attached to CHzCOOH and hi) an octyl phenol ethoxy lated with 52% by weight of ethylene oxide in the weight ratio 4:1.

2 Coacervate 13 includes (i) Oil-16 linear alcohol ethoxylated with 6.6 moles of ethylene oxide and attached to CHzCOOH and (11) 011-19 linear alcohol ethoxylated to greater than 67% content of ethylene oxide, in the weight ratio of 4:1.

In each case the coacervate system in acid form was first neutralized in situ with soda ash before the addition of the other builders.

EXAMPLE 6 Average value Formulation 14 46.6 Cotton {52.0 H

Cotton 50.7 Polyester 52.2

TABLE VI-Continued Formulation 15 53.4 Cotton Cotton 53.7 Polyester 54.4

Modifications are possible within the scope of the invention.

I claim:

1. A phosphate-free heavy duty household detergent composition in the form of a solid free-flowing powder and consisting of 0 to about 43.7% by weight of sodium sulphate, about 6 to about 12% by weight of sodium silicate, 0 to about 20% by weight of the trisodium salt of nitn'lotriacetic acid, about 10 to about 44% by weight of soda ash, O to about 6% by weight of borax, the total sodium salts content being about 77.7 to about 85.2% of the composition, up to about 2% by weight of an antiredeposition agent, up to about 0.3% by weight of optical brighteners, 0 to about 0.27% by Weight of a foam stabilizer and about 14 to about 20% of detergent active components consisting of (a) about 8 to about 20% of a coacervate system consisting of (i) an alkyl polyoxyethylene acetic acid or amine or alkali metal salt thereof, in which the alkyl group contains from 12 to 18 carbon atoms and containing from 4.5 to 8.5 oxyethylene groups and (ii) and alkyl phenol in which the alkyl group contains from 8 to 12 carbon atoms ethoxylated with from 3.5 to 10 moles of ethylene oxide, the Weight ratio of (i) (ii) being about 4:1, (b) 0 to about 6% by weight of an alkyl aryl sulphonated anionic'surfactant and (c) 0 to about 6% by weight of an ethoxylated alkyl phenol nonionic detergent other than component (ii) of said coacervate system, said composition when dissolved in water in the proportion of grams to 10 gallons of water providing an aqueous solution having a pH of about 9 to 10.5.

2. The composition of claim 1 wherein said coacervate system consists of (i) a C1345 alcohol ethoxylated with about 5.5 moles of ethylene oxide attached to a group and (ii) an octyl phenol ethoxylated with about 52% by weight of ethylene oxide, in the weight ratio of 4'1 3. The composition of claim 2 wherein said alkyl aryl sulphonate is dodecylbenzyl sulphonate.

4. The composition of claim 2 wherein said non-ionic detergent is a nonyl phenol ethoxylated with about 9.5

moles of ethylene oxide.

References Cited UNITED STATES PATENTS OTHER REFERENCES Synthetic Detergents by A. Davidsohn et al., pp'22 and 23, published by Leonard Hill, London, 1967. TP992, .5, .D3

LEON D. ROSDOL, Primary Examiner D. L. ALBRECHT, Assistant Examiner U.S. Cl.X.R.

252-89, 135, 539, 540, 558, 559, Digest -1