Environmentally Compatible Laundry Detergent

Abstract

Laundry detergents wherein the active surfactant ingredients have the formula RO--(CH.sub.2 CH.sub.2 O).sub.n --(CH.sub.2).sub.x --CHR'COOM wherein R is a hydrocarbon radical of about 12-22 carbon atoms, R' is H or lower alkyl, n is an integer of 1 to about 8, x is 0 or 1 and M is an alkali metal, amine or ammonium radical, are highly effective and are readily biodegradable. The active ingredients are especially responsive to nonphosphate builders.

Description

BACKGROUND OF THE INVENTION

As a practical matter, most present commercial laundry detergents require large amounts of builders to be effective. The most effective and widely used builders are the phosphates. Now that phosphate builders are being restricted in many localities because of the environmental damage attributed to them, a widespread search has been launched for detergents that can be adequately built with phosphate-free builders.

The active surfactants used in the present invention include known compounds that have been used or recommended for use in shampoos, cosmetics, textile desizers, wool scouring agents, and the like (Felletschin, J. Soc. Cosmetic Chemists, 15, 250 (1964); "Detergents for the Textile Industry," Technical Bulletin, Sandoz, Inc.; U.S. Pat. No. 2,183,853, British Pat. Nos. 926,898 and 793,113; French Pat. Nos. 2,014,084 and 2,042,793; Swiss Pat. No. 499,617; Chem-Y Technical Bulletins E-401, -402 and -403, and "Lauryl (poly-1-oxypropene)oxaethane Carboxylic Acids," Fabriek van Chemische Produkten N.V., Noordstraat 49, Bodegraven, Holland).

The polyethoxylated fatty alcohols, RO(CH.sub.2 CH.sub.2 O).sub.n --H, which may be regarded as the parents of the present surfactants, have been extensively studied. It has been noted that their most active members are those in which the fatty alcohol component, ROH, is near the lower end of the series, i.e., in the range of C.sub.12 to C.sub.14, and that as the number of ethoxyl groups, n, is increased, the surfactancy increases up to a value of n of about 8-10, while above this value the surfactancy changes but little (Nonionic Surfactants, M. J. Schick, editor, Vol. 1, pp. 102-114 (1967)). The surfactants used in the present invention have been found to generally follow the same pattern when tested in the absence of builders.

SUMMARY OF THE INVENTION

The invention is in the use as laundry detergents of phosphate-free built detergent compositions wherein the active surfactant ingredient has the formula

RO--(CH.sub.2 CH.sub.2 O).sub.n --(CH.sub.2).sub.x --CHR'COOM

wherein R is a hydrocarbon radical of about 12-22 carbon atoms; R' is H or lower alkyl; n is an integer 1 to about 8; x is 0 or 1 and M is a salt-forming alkali metal, ammonium or amine radical.

Surfactants of the above type are readily biodegradable. Thus, the invention provides environmentally compatible detergents that are also highly effective.

DETAILED DESCRIPTION OF THE INVENTION

The active surfactant ingredients of the laundry detergents of the invention are a well-known class of compounds and additional members of the class can be made by the methods used to make the known ones.

The R group in the above formula is preferably a fatty alcohol radical of 14-20 carbon atoms, such as palmityl, stearyl, oleyl, and the like, or mixtures thereof. Generally, the products made from mixtures are somewhat more effective than those made from a single pure fatty alcohol. In the preferred surfactants, n is 2-6, x is O and R' is H. Also preferred are the linear primary alcohols, although secondary and/or branched alcohols may also be used.

The surfactants of the invention are compatible with the usual laundry detergent additives, such as bleaches, brighteners, anti-redeposition agents, foam regulators, fillers, granulating agents, etc. Their effectiveness is unexpectedly enhanced by the phosphate-free builders, such as the alkali metal borates, silicates and carbonates. Other useful builders include the alkali metal or ammonium carboxylates, e.g., the citrates, mellitates, diglycolates, oxydisuccinates, ethylenediaminetetracarboxylates, nitrilotriacetates, N-hydroxyethyliminodiacetates, acetamidonitrilodiacetate and the like. Other suitable builders include those disclosed in U.S. Pat. No. 3,308,067.

The most convenient procedure for making the active surfactants used in the invention comprises (1) condensing ethylene oxide with the long chain fatty alcohol and (2) "capping" the resulting polyglycol monoether with a carboxyalkyl group, such as carboxymethyl or 1-carboxy-1-butyl. The capping is conveniently effected by reaction with the appropriate chloro- or bromo- carboxylic acid in the presence of alkali. Such reaction is ordinarily not complete; hence, the reaction product often contains minor amounts of uncapped polyglycol monoether. While methods are available for separating the uncapped material as well as for assuring essentially complete capping, they are usually tedious and expensive. Fortunately, it has been found that minor proportions of such uncapped material are not particularly harmful, and may even be advantageous, especially since they are less expensive than the capped material.

The practice of the invention is illustrated by the following tests and examples.

Detergency Evaluation Tests

A number of standard tests were carried out to demonstrate the efficiencies of the new formulations. These tests are described below.

Terg-O-Tometer Test

One liter of standard 150 ppm. hard water (2:1 calcium:magnesium ions) is placed in each of 4 stainless steel beakers of a Terg-O-Tometer (U.S. Testing Co., Inc., Model 144) and heated to 120.degree.F. Standard soiled test swatches are prepared by soaking 5 .times. 5 inch pieces of the desired fabric (such as bleached and desized cotton, style S/400W, from Test Fabrics, Inc.) for a minimum of 10 minutes in a soiling solution made from mixing 30 g. of vacuum cleaner soil which passed through a 270 mesh standard screen with three liters of distilled water. Most of the water is removed by pressing between paper towels and drying is completed by placing for 10 minutes in a 110.degree.-120.degree.F. forced-air oven. Three of the soiled swatches and one clean swatch for measuring anti-redeposition for each fabric being tested are placed in each test beaker along with the detergent being evaluated and the mixtures are agitated in the Terg-O-Tometer for 10 minutes at 100 rpm. The swatches are then removed, rinsed first by hand in lukewarm tap water and then in the (cleaned) test beaker containing one liter of the standard hard water for 5 minutes at 100 rpm. This test evaluates the detergency on two or three fabrics simultaneously. These are cotton, 65/35 cotton-polyester blend and the same blend with a permanent press finish.

The swatches are then removed, partially dried between paper towels and then ironed dry using a cotton pressing cloth. The degree of whiteness is determined by reading the reflectance of the twice-folded swatch on a standardized Photovolt Corporation Reflectometer, Model 610, using a green tristimulus filter. The average of four readings of each test swatch is compared with that of swatches washed in a commercial detergent, Tide (T.M., Proctor & Gamble Co.) or Ivory (T.M., Proctor and Gamble Co.) soap flakes.

Repetition of the above for 2 more cycles gives a "3-cycle detergency" reading, which is the reflectance reading after the third cycle, usually compared with that of the standard. As a general rule, brightness differences in swatches having reflectometer readings within two units of one another cannot be distinguished by the human eye. The effects of optical brighteners in e.g., the commercial materials are practically eliminated in the reflectometer by the use of the light filter.

Launderometer Test

In a series of detergency tests similar to those above, the efficacy of various conventional builders was evaluated, using a commercial laundry detergent (0.2 percent) as a comparison. Some of the tests were run in a Terg-O-Tometer, as described above, while others were run in a Launderometer, using 200 ml. of 150 ppm. hardness water at 120.degree.F. with a 15 minute wash cycle and a 5 minute rinse cycle. All tests reported herein were made in the Terg-O-Tometer unless otherwise specified.

In some experiments an artificial oily soil was made by applying a 2 percent solution in perchloroethylene of an 80:20 mixture of lanolin and oleic acid to the soiled fabrics.

The surfactants were used at the level of 0.04 percent, based on wash water, unless otherwise indicated, and were of the formula

RO--(CH.sub.2 CH.sub.2 O).sub.n --CH.sub.2 COONa

wherein R is a straight-chain alkyl group having the carbon content indicated in the table below where a range is shown, e.g., C.sub.12.sub.-18, a commercial mixture of fatty alcohols of the indicated chain length was used in making the surfactant. In the tables, the surfactant is identified by R and n as shown in the above formula and was used at 0.04 percent concentration unless otherwise noted; the fabrics used were cotton, a 65/35 polyester/cotton blend or the same blend treated with a permanent press resin (P.P. Blend). The commercial detergent used for comparison was used at a concentration of 0.2 percent.

The builders used in Examples 1-15 (except Example 6 and 10) were as follows (all percentages are based on total wash water): B.sub.1 consisted of Na.sub.2 CO.sub.3, 0.108 percent, Na.sub.2 SiO.sub.3.sup.. 5H.sub.2 O, 0.0432 percent, carboxymethyl cellulose, 0.002 percent; B.sub.2 consisted of sodium silicate sold under the trade name Silicate BW (ratio of SiO.sub.2 to Na.sub.2 O, 1.6), 0.1 percent (water-free basis), Na.sub.2 SO.sub.4, 0.058 percent and carboxymethyl cellulose, 0.002 percent.

In Examples 16-34, the sodium silicate used was sold under the trade name Silicate G (ratio of SiO.sub.2 /Na.sub.2 O, 3.2). The use of this silicate results in a lowered pH of the wash solution without any adverse effect on the cleaning performance.

In some examples the detergency was compared to that of the American Association of Textile Chemists and Colorists (AATCC) standard detergent. Its composition is as follows:

Sodium linear alkylsulfonate 14 % Fatty alcohol ethoxylate 2.3 Soap 2.5 Na tripolyphosphate 48.0 Sodium silicate (SiO.sub.2 /Na.sub.2 O=2.0) 9.7 Sodium sulfate 15.4 Na CMC .25 Misc. 7.85 100.00

TABLE I __________________________________________________________________________ 3-Cycle Reflectance Detergent Redeposition Ex. R n Machine Soil Fabric Tide B.sub.1 B.sub.2 Tide B.sub.1 B.sub.2 __________________________________________________________________________ 1 C.sub.18 8.3 Laund. Oily Cotton 60 58 58 83 85 85 2 C.sub.12.sub.-18 5.8 Laund. Oily Cotton 60 61 60 83 85 85 3 C.sub.18 8.3 Terg. Dry Cotton 75 75 76 83 83 84 Blend 71 71 68 79 80 80 4 C.sub.12.sub.-18 5.8 Terg. Dry Cotton 72 72 66 84 83 84 Blend 71 69 64 80 79 79 5 C.sub.18 6.8 Terg. Oily Cotton 69 69 69 84 84 86 Blend 66 64 59 79 80 81 6 C.sub.18 6.8 Terg..sup.a Oily Cotton 66 67.sup.b 82 83.sup.b 7 C.sub.12 1.8 Laund. Oily Cotton 66 63 83 83 P.P. Blend 68 64 8 C.sub.12 3.1 Laund. Oily Cotton 66 61 Blend 70 62 9 C.sub.18 3 Laund. Oily Cotton 66 62 Blend 70 61 10 C.sub.18 6.8 Terg..sup.c Oily Cotton 73 71.sup.d 90 91.sup.d __________________________________________________________________________ .sup.a 4 cycles instead of 3 .sup.b Builder was same as B.sub.1 except that the sodium silicate was replaced with an equal amount of sodium tripolyphosphate .sup.c Two cycles instead of 3 .sup.d Builder was same as B.sub.1 except that silicate was reduced to 0.012% and sodium diglycolate (0.04%) was added

To illustrate the unexpected improvement in the detergency of surfactants having low proportions of oxyethylene groups (low values of n) in the molecule when built with silicate-based builders, the following examples were run. In this series, the fatty alcohol used to make the surfactants was a commercial mixture of C.sub.16.sub.-20 alcohols. The builder formulation was B.sub.1, described above.

TABLE II ______________________________________ Effect of Builder B.sub.1 on Third Cycle Reflectance of RO(CH.sub.2 CH.sub.2 O).sub.n -CH.sub.2 COONa ______________________________________ Third Cycle Reflectance Permanent Press Average Cotton Blend Ex. No. Value of n Unbuilt Built Unbuilt Built ______________________________________ 11 10.5 68.8 -- 51.5 -- 12 7.9 68.0 69.4 52.0 54.9 13 5.7 66.0 73.6 49.3 61.7 14 4.3 61.8 74.0 50.0 68.1 15 2.5 -- 73.0 -- 62.5 ______________________________________

In another series of experiments, the proportion of sodium silicate (SiO.sub.2 /Na.sub.2 O = 3.2) was varied. The active surfactant was that of Example 14. The formulation was as follows:

Na.sub.2 CO.sub.3 54% Na carboxymethylcellulose (Na CMC) 1% Active surfactant 10% Na silicate as indicated Na.sub.2 SO.sub.4 balance

The use level was 2.0 g./l.

TABLE III __________________________________________________________________________ Third Cycle Reflectance % Sodium 65/35 Dacron/ 65/35 Dacron/Cotton Blend Ex. No. Silicate Cotton Cotton Blend with Permanent Press Finish __________________________________________________________________________ 16 20 68.3 63.0 61.6 17 15 67.2 62.3 60.4 18 10 67.2 59.1 58.9 19 5 66.0 59.4 58.0 __________________________________________________________________________

In a similar series of experiments, the effect of varying the concentration of sodium carbonate was noted.

The formulation and use level were the same as in Examples 16-19 except that the silicate was constant at 15 percent while the carbonate varied as shown below.

TABLE IV __________________________________________________________________________ Third Cycle Reflectance 65/35 Dacron/Cotton % pH Wash 65/35 Dacron/ Blend with Permanent Ex. No. Na.sub.2 CO.sub.3 Solution Cotton Cotton Blend Press Finish __________________________________________________________________________ 20 70 10.45 70.0 65.0 63.1 21 54 10.30 71.5 64.9 64.2 22 40 10.15 71.5 64.5 62.1 23 25 10.00 70.3 60.4 57.1 __________________________________________________________________________

The following experiments show that the sodium carbonate used in the builder in the previous experiments can be replaced with sodium sesquicarbonate. The formulation was the same as in Examples 20-23 except that the sesquicarbonate and silicate were as indicated.

TABLE V __________________________________________________________________________ Third Cycle Reflectance 65/35 Dacron/Cotton % Sodium % Sodium pH Wash 65/35 Dacron/ Blend with Permanent Ex. No. Sesquicarbonate Silicate Solution Cotton Cotton Blend Press Finish __________________________________________________________________________ Control.sup.(a) 20 10.35 69.4 64.2 62.9 24 69 20 9.90 68.5 64.6 63.5 25 54 35 9.80 68.1 63.8 61.6 26 35 54 9.75 69.3 61.9 60.4 __________________________________________________________________________ .sup.(a) 54% Na.sub.2 CO.sub.3

While the use of sodium carboxymethylcellulose as an antideposition agent is conventional, the following experiments demonstrate that it is effective with the detergents of the invention. The formulation and use level were the same as in Example 17 except that the Na CMC level was varied.

TABLE VI __________________________________________________________________________ Third Cycle Reflectance 65/35 Dacron/ 65/35 Dacron/Cotton Blend with Ex. No. % CMC Cotton Cotton Blend Permanent Press Finish __________________________________________________________________________ 27 2.0 64.2 60.0 55.0 28 1.0 68.4 60.2 58.4 29 0.5 67.8 61.5 57.7 30 0.0 66.3 58.8 56.6 __________________________________________________________________________

The effectiveness of the detergents of the invention in water of widely varying hardness is illustrated by the following experiments. The formulation and use level were as in Example 17.

TABLE VI ______________________________________ Third Cycle Reflectance 65/35 Dacron/Cotton Water Blend with Permanent Ex. No. Hardness (ppm).sup.(a) Cotton Press Finish ______________________________________ 31 50 74.6 61.3 32 100 75.5 64.0 33 150 74.7 63.0 34 300 73.9 62.1 ______________________________________ .sup.(a) Ca.sup.+.sup.+/Mg.sup.+.sup.+ is 2/1; calculated as ppm CaCO.sub.3

The following experiments show the exceptional effectiveness of the iminoacetate-type builders with the active surfactants of the present invention. In these experiments, the formulation consisted of the active ingredient (surfactant) of Example 14 in the indicated amount, sodium silicate (SiO.sub.2 /Na.sub.2 O = 3.2), 12 percent, Na CMC, 1 percent, disodium N-hydroxyethyliminodiacetate (SHIM), as indicated, the balance being Na.sub.2 SO.sub.4. These detergents were used at the level of 2 g./l.

TABLE VIII __________________________________________________________________________ Third Cycle Reflectance 65/35 Dacron/Cotton Blend with Permanent Ex. No. Surfactant, % SHIM, % Cotton Press Finish __________________________________________________________________________ Control.sup..noteq. 75.6 68.8 35 20 50 77.3 68.4 36 10 50 76.2 67.4 37 20 35 76.0 67.7 38 10 35 77.9 68.5 39 10 20 77.9 67.8 40 5 20 76.1 61.8 __________________________________________________________________________ .sup..noteq.AATCC standard at 2.0 gms./l; ave. of two runs

The following experiments show the use of nitrilotriacetate (Na salt) (NTA) as a builder. The surfactants were all derivatives of a commercial mixture of C.sub.16 -C.sub.20 fatty alcohols and differed only in the number of oxyethylene groups, n, thereon. The pH of all the wash solutions was 9.8. The formulation, used at a level of 2 g./l., was

Sodium silicate (SiO.sub.2 /Na.sub.2 O = 3.2) 10% Surfactant 20 Na CMC 1 NTA as indicated Na.sub.2 SO.sub.4 balance

TABLE IX __________________________________________________________________________ Third Cycle Reflectance 65/35 Dacron/Cotton n in the NTA Blend with Permanent Ex. No. Surfactant Concentration (%) Cotton Press Finish __________________________________________________________________________ Control.sup.(a) -- 68.5 71.6 41 2.0 35 69.7 68.3 42 4.3 35 70.0 66.0 43 5.7 35 69.6 65.6 44 7.9 35 67.2 65.2 45 4.3 50 69.0 69.5 46 4.3 20 67.1 62.8 __________________________________________________________________________ .sup.(a) Tide (35% STPP), 2 g./l.

The utility of Na mellitate as a builder is shown in the following experiments paralleling those shown in Table IX.

TABLE X __________________________________________________________________________ Third Cycle Reflectance Mellitic Acid 65/35 Dacron/Cotton n in the (Na salt) Blend with Permanent Ex. No. Surfactant Concentration Cotton Press Finish __________________________________________________________________________ Control.sup.(a) -- 78.0 72.8 47 2.0 35 74.9 58.3 48 4.3 35 77.5 66.7 49 5.7 35 77.1 65.2 50 7.9 35 76.0 62.1 51 4.3 50 76.5 67.4 __________________________________________________________________________ .sup.(a) Tide (35% STPP), 2.0 g./l.

The following series of experiments illustrate the effect of the length of the carbon chain of the fatty alcohol used in making the surfactant.

The formulation used was

Surfactant as indicated Sodium carbonate 54% Sodium silicate (SiO.sub.2 /Na.sub.2 O = 3.2) 15 Na CMC 1 Sodium sulfate balance

The use level was 2 g./l. in all cases.

The surfactants are identified in the following table by the headings R and n, which indicate the number of carbon atoms in the fatty alcohol moiety and the number of oxyethylene groups, respectively, in the acetate-capped surfactants.

The reflectance values in the following table are the differences in the reflectances of samples washed with the test material and samples washed in parallel experiments with the AATCC standard detergent used at the same level. Positive values indicate performance superior to the standard.

__________________________________________________________________________ Third Cycle Reflectance Deviation from AATCC Standard Surfactant 65/35 Blend Ex. No. R n Conc., % Cotton Dacron/Cotton P.P. Blend __________________________________________________________________________ 52 12 1.8 20 -5.0 -7.2 -5.2 53 12 3.1 20 -3.6 -6.9 -7.5 54 12-18 3.1 20 -1.1 -1.9 -2.9 55 12-18 4.0 20 -1.9 -2.5 -8.3 56 16-18 1.4 20 -2.8 --.sup.a -18.7 57 16-18 3.7 10 +4.3 -4.5 -3.5 58 16-18 5.8 10 +3.3 -8.6 -7.6 59 16-18 8.0 10 -0.4 -12.3 -14.5 60 18 5.9 20 -1.9 -9.9 -8.7 61 18 8.3 20 -0.3 -8.5 -12.0 62 16-20 2.0 20 +2.4 -5.2 -6.9 63 16-20 4.3 20 +3.6 -1.1 -1.8 64 16-20 4.3 10 +2.6 -5.2 -7.2 65 16-20 5.7 20 +2.3 -4.7 -9.1 66 16-20 7.9 20 -0.6 -9.1 -14.4 __________________________________________________________________________ .sup.a Expt. not run

Not only are the detergents free of phosphate builders but the active surfactants thereof are readily biodegradable, especially those made from straight-chain fatty alcohols. Those made from branched-chain synthetic fatty alcohols are less readily degraded. Moreover, all of them are less toxic to fish and animals than many of the present widely used commercial detergents.

While the above examples illustrate only a limited variety of nonphosphate builders, and show them only in a limited range of proportions, it is to be understood that any of such builders in any conventional proportion can be used in the present invention. For example, when using a precipitating builder, such as the combination of alkali metal silicate and alkali metal carbonate, the builder may suitably constitute about 50-95 percent of the total detergent formulation (dry weight basis), though the optimum is usually about 60-80 percent. When using a chelating builder, such as the polycarboxylic acid salts, it may constitute about 10-50 percent, and preferably about 20-35 percent of the total detergent formulation. Because of their high activity, the active surfactants usually constitute only about 3-25 percent of the total formulation, the preferred proportion being about 6-12 percent. The balance is made up of conventional additives, fillers, moisture, etc.

While the alkali metal salts of the surfactant acids are preferred, the ammonium and amine salts are also effective. Suitable amines include the lower alkyl (e.g., methyl, ethyl and butyl) amines and the lower alkanolamines (e.g., ethanol-, propanol- and butanolamines).

While the disclosed surfactants may be (and preferably are) the sole active surfactants in the detergents, minor amounts (up to about 20 percent of the total surfactant) of other surfactants may be included, e.g., soaps, alkyl sulfates or alkyl or alkaryl sulfonates.

Claims

We claim:

1. An environmentally compatible laundry detergent consisting essentially of

1. as the active surfactant ingredient, a compound of the formula

RO--(CH.sub.2 CH.sub.2 O).sub.n --(CH.sub.2).sub.x CHR.sub.1 COOM

wherein R is the hydrocarbon chain of a fatty alcohol of about 12 to 22 carbon atoms, n is an integer 2 to 6, x is 0 or 1, R.sub.1 is H or lower alkyl and M is alkali metal, ammonium or amine radical, and

2. a substantially phosphate-free detergent builder.

2. The detergent of claim 1 wherein M is alkali metal.

3. The detergent of claim 1 wherein R.sub.1 is H.

4. The detergent of claim 1 wherein x is 0.

5. The detergent of claim 1 wherein R has about 14-20 carbon atoms.

6. The detergent of claim 1 wherein the builder is a mixture of alkali metal silicate and alkali metal carbonate.

7. The detergent of claim 5 wherein the weight ratio of silicate to carbonate is about 1:1 to about 1:10.

8. The detergent of claim 1 containing about 3-25 percent by weight of active surfactant.

9. The detergent of claim 1 containing about 50-95 percent by weight of builder.

10. The detergent of claim 6 wherein the carbonate is sesquicarbonate.

11. The detergent of claim 1 wherein the builder is an alkali metal salt of a polycarboxylic acid.

12. The detergent of claim 11 wherein the polycarboxylic acid is an aminopolycarboxylic acid.

13. The detergent of claim 11 wherein the polycarboxylic acid is citric, mellitic, diglycolic, oxydisuccinic, nitrilotriacetic, N-hydroxyethyliminodiacetic, ethylene-diaminetetraacetic or acetamidonitrilodiacetic acid.

14. The detergent of claim 7 containing about 3-25 percent by weight of active surfactant and about 50-95 percent by weight of builder.

15. The detergent of claim 13 containing about 3-25 percent by weight of active surfactant and about 10-50 percent by weight of builder.

16. The detergent of claim 1 consisting essentially of about 3-25 percent by weight of active surfactant and about 10-95 percent of builder, said builder consisting essentially of one or more alkali metal borates, silicates or carbonates, citrates, mellitates, diglycolates, oxydisuccinates, ethylene-diaminetetracarboxylates, nitrilotriacetates, N-hydroxy-ethyliminodiacetates, acetamidonitrilodiacetates or a mixture of two or more thereof.