Polyelectrolytes As Detergent Builders

Abstract

A non-polluting builder composition for cleansing purposes is described consisting of composite of a polyelectrolyte and the alkali metal salt of a weak acid. Such builder compositions can replace the phosphorous and nitrogen-containing builders previously used in cleansing and laundry detergents with regard to effectiveness in hard water at one-tenth and one-fifth the concentrations of such previously used builders. In hard water, such composite builders prevent the precipitation of insoluble calcium soaps which occurs in household and laundry detergent compositions utilizing either component alone as a builder. The previously noted stabilizing effects of the polyelectrolyte with regard to enzymes and bleaches is not decreased by the added components of these composite builders.

Description

FIELD OF THE INVENTION

This invention relates to detergent compositions useful for household and laundry service and particularly relates to builders for such compositions that are devoid of pollutant or toxic potentials. The term "builders" refers to the class of compounds and compositions which improve detergency levels of synthetic detergents and soaps. By utilizing builders, it is possible to prepare detergent compositions having superior detergency as measured by removal of dirt and superior qualities with regard to the redeposition of the dirt that is loosened during the washing process. Additionally, by utilizing builders, it is possible to reduce the final cost of the detergent compositions.

The exact mechanism by which builders achieve their function in detergent compositions is not well understood. Consequently, it is not possible to predict classes of compounds or compositions which would tend to function as builders. Presently, two criteria are used for evaluating the effectiveness of builder compositions; detergency and anti-soild redeposition. Convenient objective means for measuring and evaluating these qualities will be described below.

In the recent past, the most commonly used builder materials have been the water-soluble inorganic alakaline phosphates and polyphosphates. At present, their usage is being interdicted. The phosphate ion is a nutrient for algae which are a prime cause of eutrification of our lakes and waterways. The phosphate ion from laundry and household use of detergents appears to enhance the growth of algae and the sudden overgrowth of algae interferes with the ecological balance within the lakes and waterways into which such waste waters are discharged.

A recently commercialized builder material, nitrolotriacetic acid, had been proposed as a replacement for phosphate builders such as the polyphosphates. However, recent research has indicated the possibility of birth defects in test animals after exposure to combinations of nitrilotriacetic acid, which is a nitrogen-containing chelating agent, with certain toxic salts. It appears that this builder molecule in some manner permits the transport of toxic cadmium and mercury through tissue membranes. Consequently, this material is less than desirable for utilization in and around the normal household and for discharge into our environmental waters.

It is consequently an object of this invention to furnish a builder which is at least as effective as phosphates for use in detergent compositions.

It is a further object of this invention to provide a builder which is non-toxic and contains neither nitrogen phosphorus as readily available nutrient elements for the overgrowth of algae or other undesirable aquatic plants.

It is a further object of this invention to provide a builder which can be utilized for the preparation of ecologically balanced detergent products.

The above objects are achieved by the utilization in cleansing compositions, comprising detergents and builders, a builder that is a composite of certain polyelectrolytes and alkaline-reacting salts of alkali metals with weak acids. The polyelectrolyte component of the composite builders of this invention are the copolymer of lower alkyl vinyl ethers with maleic acid or its anhydride. Preferred is PVM/MA of Polyvinyl methyl ether/Maleic Anhydride and its hydrolyzed product. The anhydride copolymer has the configuration of: ##SPC1##

where R is lower alkyl up to 6 carbon atoms, x is greater than 10, indicating polymers of molecule weight ranging from about 1,500 to in excess of 2,500,000. The anhydride copolymer is also useful in its hydrolyzed form and its salts. The hydrolyzed form, polyvinyl methyl ether/maleic acid has the following configuration: ##SPC2##

where R and x are as indicated above.

Viscosity measurements are commonly used as an indication of the average molecular weight of the polymeric composition. The K value (Fikentscher) of any particular mixture of polymers is calculated from viscosity data and is useful as an indication of the average molecular weight of such mixtures. Its determination is fully described in MODERN PLASTICS 23 No. 3, 157-161, 212, 214, 216, 218, (1945) and is defined as 1,000 times k in the empirical relative viscosity equation:

(log 10 .eta.rel = 75k.sup.2)/(I + 1.5kC ) + k

wherein C is the concentration in grams per hundred cc. of polymer solution and .eta. rel is the ratio of the viscosity of the solution to that of pure solvent. The K values are reported as 1,000 times the calculated viscosity coefficient in order to avoid the use of decimals. The preferred interpolymers employed in the present invention have k values of from about 10 to about 200.

K values and specific viscosities (.eta. sp) are interconvertible and are related through relative viscosity (.eta.0 rel). Thus, when viscosity measurements are taken on solutions which have a concentration of 1.00 gram of polymer per deciliter of solution at 25.degree.C (C = 1), the relationships are as follows:

(log e .eta.rel)/C

and intrinsic viscosity (the limit of inherent viscosity as C approaches 0 have the dimensions of dilution, i.e., the reciprocal of concentration. Intrinsic viscosity and K are intended to be independent of concentration. The preferred interpolymers are those having a specific viscosity ranging from about 0.1 to about 4.5.

Preferred electrolytes are marketed in the United States by GAF Corporation as Gantrez AN, poly (methyl vinyl ether) maleic anhydride at various molecular weight grades as designated by their viscosity as follows:

Viscosity Average Molecular Gantrez .eta. sp.* Weight ______________________________________ AN-119 0.1 - 0.5 250,000 AN-139 1.0 - 1.4 500,000 AN-149 1.5 - 2.0 750,000 AN-169 2.6 - 3.5 1,250,000 AN-179 3.6 - 4.5 2,250,000 ______________________________________ *as determined on a solution of 1.0 gm. of the copolymer in 100 ml of methyl ethyl ketone at 25.degree. C.

The two essential ingredients for cleansing compositions comprise the detergent compound itself and the builder. Among the detergent compositions useful in conjunction with the builders of this invention are any of the classes of detergents commonly used for laundry and household cleansers. These fall into the general classes of nonionic, anionic, cationic, and amphoteric detergents. Detergents from natural and synthetic sources falling within these classes are amply set forth in "Detergents and Emulsifiers," J. W. McCutcheon, editor, published by J. W. McCutcheon, Inc., 236 Mount Kemble Ave., West Orange, N.J.

The nonionic detergents as the name implies, are those which do not ionize in water solution. Among the nonionic synthetic detergents commonly used are those formed by the condensation reaction of ethylene oxide units with hydrophobic bases among which are ethylene oxide condensates with alkyl phenols wherein the alkyl group on the phenol contains from six to about 12 carbon atoms in either straight or branched-chain configuration and the ethylene oxide is present in amounts equal to 10 or 12 units of ethylene oxide per mole of alkyl phenol. Further nonionic detergents are the group of aliphatic alcohols condensed with ethylene oxide, i.e., alcohols having eight to 18 carbon atoms condensed with 8 to 30 units of ethylene oxide among which may be mentioned the condensate of 10 to 30 moles of ethylene oxide with coconut alcohol fractions having 10 to 14 carbon atoms. Other nonionic synthetic detergents include the condensation products of ethylene oxide with propylene oxide and diamines or phosphates and the long-chain tertiary amines, oxides and tertiary phosphines oxides. These are eschewed for the purposes of this invention for reasons of their pollution proclivities.

The preferred nonionic detergents for the purposes of this invention are the condensates of nonylphenol with ethylene oxide offered commercially under the Igepal trademark by GAF Corporation, New York City.

Among the anionic detergent compounds useful in the compositions of this invention, there must be mentioned ordinary soap. This is the alkali metal salts of long-chain fatty acids having at least 12 carbon atoms. Suitable soaps are the sodium, potassium and ammonium salts of fatty acids, derived from oils and fats from vegetable and animal sources.

Among the anionic synthetic detergent compounds are the water-soluble salts and particularly the alkali metal salts of organic sulfuric reaction products such as the sulfonates and sulfates of alkyl and alkaryl moieties containing from eight to about 22 carbon atoms in the alkyl portion of the radical. Commercially important are the linear alkyl sulfonate sodium salts such as sodium lauryl sulfonate and the sodium and potassium alkyl benzene sulfonates such as are described in U.S. Pat. Nos. 2,220,009 and 2,477,383.

While the builders of this invention may be utilized with the amphoteric synthetic detergents, it is preferred not to do so since they generally fall within the broad class of amine derivatives and due to the chelating nature of most of such amphoteric compounds with heavy metals, it is preferred to avoid solubitized forms of such toxic materials in household environments.

The cationic synthetic detergents are generally the quaternary ammonium salts. Here due to the particular nature of the quaternary ammonium compounds, i.e., their ready biodegradeability, an exception is made concerning the utilization of nitrogen-containing detergents for general household purposes. These compounds are particularly useful due to their cold water detergency characteristics. Particularly useful for cold water laundry detergents is Soromine CAZ 70 (GAF Corporation) a cationic complex polyalkyl amido imidezolinium sulfate. Usually the cationic detergents are unstable in the presence of alkaline pH solutions but the cationic detergents are fully compatible with the polyelectrolyte/alkaline salts composite builder of this invention. The particular composition composite builders of this invention possibly due to the presence of the polyelectrolyte appear not to have this adverse effect.

In general, the detergent and builder composite of the present invention are utilized according to the following proportions:

composite builder -- parts by weight -- 5 to 70

surfactant -- parts by weight -- 5 to 100

The above tabulation is a representation of the proportions of the active detergent to the composite builder in detergent cleansing compositions according to this invention. Complete detergent compositions, of course, contain many ancillary ingredients useful for other purposes but having little to do directly with the problem of soil removal and the prevention of soil redeposition which combined indicate the cleansing effectiveness of the cleansing compositions. Among ancillary agents which may be included in complete detergent cleansing and/or laundry compositions to adapt to certain specific applications, there may be mentioned the optical brighteners, anti-corrosives, foam stabilizers, defoaming agents, soil-suspending agents, enzymes, bleaches and the like. The composite builder of this invention does not interfere with most of these ancillary materials.

The final detergent cleansers of this invention may be compounded as liquids or solids.

Additionally, there may be employed coloring materials, perfumes and corrosion inhibitors. In general, the detergent cleansing concentrates in the proportions tabulated above, plus any ancillary agents are then diluted with water to the extent of 500 to 20,000 parts by weight of water. Water presents its own problems depending on the degree of hardness and the presence of unwanted ions. Hardness is measured by the amount of calcium and magnesium ions. Such ions form insoluble non-detergent curds with long-chain fatty acids thereby preventing full utilization of the detergent compounds. Other deleterious ions include iron which in alkaline solution tends to deposit as iron hydroxide, which upon drying and oxidizing leaves unsightly stains (rust spots) on laundered materials.

For general commercial practical use, it is preferred that the ratio of polyelectrolytes to alkaline salts in the composite builder, according to this invention, should range from 1 to 100 to 1 to 2 parts by weight. When the builder is used in ecologically desirable detergent compositions, the ratio of the detergent compound in the cleanser to the builder should be in the range of 8 parts by weight of the detergent to one part by weight of the builder. To the other end of the range one part by weight of the detergent to 100 parts by weight of the composite builder of this invention. They may be formulated as solid compositions in powder or shaped form or in liquid concentric form.

Table 1 below is a tabulation of concentration ranges of the preferred polyelectrolyte of this invention, PVM/MA, the preferred alkaline salts, and commercial detergent compounds to be formulated into a condensate so that as diluted, the concentrate is equivalent to industrial household and laundry products used at 1.0 grams/liter:

TABLE 1 __________________________________________________________________________ Detergent Use Range Preferred % by Weight of Solution % __________________________________________________________________________ Poly (vinyl methyl ether/ maleic anhydride or Poly (vinyl methyl ether/ maleic acid .001 - 5.0 .005 Alkali metal salts of weak acids Na.sub.2 CO.sub.3 .001 - 10.0 .050 Na.sub.2 SiO.sub.3 .001 - 10.0 .005 Borax .001 - 10.0 .005 Detergent .005 - 5.0 .0100 Optional Additives CMC 0.0 - 1.0 .0005 Optical Brightener 0.0 - 0.5 .0003 Na.sub.2 SO.sub.4 0.0 - 10.0 .0292 Sodium bicarbonate 0.0 - 10.0 -- __________________________________________________________________________

It should be noted that PVM/MA is the preferred polyelectrolyte but that mixtures of the alkaline salts may also be used in combination with sodium carbonate for this invention. This composite with soda ash is preferred on the basis of objective superiority as it has been noted that when the detergency is measured according to the objective test methods set forth below there is a synergism between the polyelectrolyte and the sodium carbonate or silicate or borate as regards the measurement of detergency at the various degrees of water hardness commonly encountered in the United States. In the Examples, Examples 1 and 7 show the detergency as a function of water hardness for soda ash and sodium silicate polyelectrolyte (PVM/MA) and the synergism found in the salts with this polyelectrolyte as measured in the Terg-O-Tometer Detergency Test as as described in "Detergency Evaluation and Testing" (J. C. Harris, Interscience Publishers, N.Y.).

With the other commonly used polyelectrolytes, it has been found that the detergency effect with alkaline salts is merely additive. While such other polyelectrolyte/alkaline salts composites are useful, they are not as commercially attractive or as competitively attractive or as competitively cleansing or ecologically desirable as the composites of this invention.

As noted, the preferred polyelectrolyte of this invention is commercially marketed in various molecular weight ranges. The various grades of polyelectrolyte are soluble in water and within the concentration and pH ranges set forth, the molecular weight has little or no effect upon the efficiacy of the builder compositions of this invention.

In order to exemplify the present invention and to comparatively demonstrate the advantages thereof, a series of formulations were prepared and standardized samples were washed in these formulations in order to evaluate their detergency and antisoil redeposition properties. The procedure used to evaluate the detergency properties of the product tested was as follows:

The Terg-O-Tometer Detergency Test as described in "Detergency Evaluation and Testing" (J. C. Harris, Interscience Publishers, N.Y.) was utilized. Standard soiled cotton cloth was purchased from Test Fabrics, Inc. and used as a means of measuring detergency properties.

The formula used to calculate percent detergency is given in "Detergency Evaluation and Testing" (p. 105) and is:

[(A - E) - B/(C - B)] .times. 100 + % Detergency

where

A = reflectance of soiled swatch after washing

B = reflectance of soiled swatch before washing

C = reflectance of redeposition swatch before washing

E = net reduction in reflectance of redeposition swatch (before washing minus after washing)

Whiteness is calculated according to a formula published in "Measurements of the Appearance of Paint Finishes" by R. S. Hunter (Official Digest, Vol. 35, No. 459, p. 250-365) where

W = g - 4 (g - b) and

G = green filter reflectance

B = blue filter reflectance

Standard soiled swatches together with unsoiled swatches were washed in the Terg-O-Tometer using a solution of the product in the designated water hardness. After washing 20 minutes, the swatches were rinsed and iron dried and then measured for reflectance using the Hunter D40 reflectometer. The data was then subjected to the whiteness formula and the % detergency formula. The results are given in the tables with each example.

EXAMPLE 1

The detergency of the preferred components of the composite according to this invention, i.e., poly (vinyl methyl/maleic anhydride) and Na.sub.2 CO.sub.3 was measured in formulations without any synthetic detergent compound present. Tests were made at various degrees of water hardness. The results clearly illustrate the detergency synergism resulting from the preferred builder composites of this invention.

__________________________________________________________________________ Composition: Gantrez AN 119 -- .01% -- .01% Na.sub.2 CO.sub.3 -- -- .05% .05% Conditions Dist. Water Plus Composition (Without Surfactant) __________________________________________________________________________ A. -- 32.2 29.2 34.8 37.5 B. 25 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 21.1 25.8 6.8 34.3 C. 100 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 7.4 7.9 -13.5 25.0 D. 200 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 -25.0 5.8 7.0 25.6 E. 300 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 -35.0 4.7 16.2 34.2 F. 1000 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 -48.0 -21.7 -3.5 16.8 __________________________________________________________________________

EXAMPLE 2

This example illustrates the detergency improvement of a complete detergent composition including a nonionic synthetic detergent Igepal CO630 (TM) marketed by GAF Corporation and which is generically described as a nonylphenol-ethylene oxide condensation product according to U.S. Pat. Nos. 1,970,578 and 2,213,472.

__________________________________________________________________________ Composition Igepal CO630 .02% .02% .02% .02% Gantrez AN119 -- .01% -- .01% Na.sub.2 CO.sub.3 -- -- .05% .05% Conditions Dist. Water Plus Detergency With Igepal CO630 __________________________________________________________________________ A. 25 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 24.7 40.2 19.2 53.6 B. 100 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 28.3 4.8 21.1 51.1 __________________________________________________________________________

EXAMPLE 3

This example illustrates a composition containing the anionic detergent dodecyl benzene sulfonate marketed by Arco Chemical Co. under the name Ultrawet 60K.

__________________________________________________________________________ Composition Ultrawet 60K .033% .033% .033% .033% Gantrez AN119 -- .01% -- .01% Na.sub.2 CO.sub.3 -- -- .05% .05% Conditions Dist. Water Plus % Detergency With Ultrawet 60K __________________________________________________________________________ A. 25 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 22.7 35.4 31.3 30.7 B. 100 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 18.5 30.0 34.1 45.3 C. 300 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 -13.0 4.1 27.2 41.5 __________________________________________________________________________

EXAMPLE 4

This example illustrates the effectiveness of the builder composite of this invention with the anionic surfactant GAFAC RA600 (TM) marketed by GAF Corporation and which is a complex organic phosphate ester based on linear alcohols.

__________________________________________________________________________ Composition GAFAC RA600 .02% .02% .02% .02% Gantrez AN119 -- .01% -- .01% Na.sub.2 CO.sub.3 -- -- .05% .05% Conditions Dist. Water Plus % Detergency with GAFAC RA600 __________________________________________________________________________ A. 25 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 32.7 31.6 37.4 37.2 B. 100 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 28.1 25.1 42.3 39.8 C. 300 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 10.7 11.5 26.6 39.8 __________________________________________________________________________

EXAMPLE 5

This example illustrates the effectiveness of the builder composite of this invention with sodium oleate or soap as the anionic detergent.

__________________________________________________________________________ Composition Na+ Oleate .02% .02% .02% .02% Gantrez AN119 -- .01% -- .01% Na.sub.2 CO.sub.3 -- -- .05 .05% Conditions Dist. Water Plus % Detergency with Sodium Oleate __________________________________________________________________________ A. 25 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 33.3 29.1 -10.7 16.3 B. 100 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 -8.0 23.3 1.8 12.4 C. 300 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 -35.0 7.0 25.1 24.8 __________________________________________________________________________

EXAMPLE 6

This example illustrates the effectiveness of the builder composite of this invention with the cationic detergent Soromine CAZ-75(TM) marketed by GAF Corporation and which is a complex polyalkyl amido imidazolinium sulfate.

__________________________________________________________________________ Composition Soromine CAZ-75 0.0266% 0.0266% 0.0266% 0.0266% Gantrez AB119 -- .01% -- .01% Na.sub.2 CO.sub.3 -- -- .05% .05% Conditions Dist. Water Plus % Detergency with Soromine CAZ-75 __________________________________________________________________________ A. 25 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 -52.8 18.3 -86.3 24.1 __________________________________________________________________________

EXAMPLE 7

This example illustrates the effectiveness of the builder composite of this invention utilizing sodium meta silicates as the alkaline salt instead of sodium carbonate. The detergency effect of the polyelectrolyte and the Na.sub.2 SiO.sub.3 of the components of the builder composite is synergistic.

__________________________________________________________________________ Composition Na.sub.2 SiO.sub.3 .05% .05% .05% .05% Gantrez AN119 -- .01% .01% -- .01% Igepal CO630 -- -- .02% .02% Conditions Dist. Water Plus % Detergency with Sodium Metasilicate __________________________________________________________________________ A. 100 ppm CaCl.sub.2, 5 ppm FeCl.sub.3 14.2 7.9 31.2 39.4 51.0 __________________________________________________________________________

As can be seen from Example 1 and 7, the combination of the poly (vinyl methyl/maleic anhydride with sodium carbonate or sodium metasilicate is more effective than either component alone. This performance is more noticeable as the water hardness increases. Examples 2, 3, 4, 5 and 6, aside from their demonstration of the effectiveness and utility of the composite builder of this invention with nonionic, anionic and cationic detergents, also demonstrate the synergistic performance of the preferred polyelectrolyte of this invention with soda ash in total formulation.

While the prime purpose of the builder composite of this invention is to provide non-polluting builders for household, industrial and laundry purposes, the novel builders may also serve not only to completely replace the phosphate and nitrogen-containing builders previously used but may also partially replace them during interim periods of product change-over. Example 8 below is a comparison of detergency and redeposition data of the commonly used builders with the composite builder of this invention and its components:

EXAMPLE 8 __________________________________________________________________________ Use Detergency Builder Compounds Concentration/% Water Hardness(ppm) Average Redeposition __________________________________________________________________________ Sodium Tripolyphosphate (STPP) 0.2 100 36.8 60.5 NTA 0.1 100 40.6 63.3 Sodium Carbonate 0.05 100 33.5 60.2 Sodium Sulfate 0.2 100 31.5 64.3 Poly (vinyl methyl/maleic anhydride) (Gantrez AN-149 pH - 7.0) 0.02 100 33.5 67.1 Poly (vinyl methyl/maleic anhydride) (Gantrez AN-149 + NaCO.sub.3) 0.02 + 0.05 100 44.0 65.0 __________________________________________________________________________

Wherever parts or percentages are mentioned, they are to be construed as parts and percentages by weight. While the invention has been demonstrated in the examples by certain specific formulations, such examples merely indicate exemplary modes and compositions but the invention is not to be construed as limited to such as the sole preferred modes and compositions as all equivalents thereto are intended.

Claims

What is claimed is:

1. A process for producing an ecologically desirable detergent composition suitable for washing textiles, comprising admixing, as essential ingredients, a detergent selected from the group consisting of nonionic, anionic, cationic and amphoteric detergents, together with a composite builder, as sole builder, consisting of a member selected from the group consisting of polyvinyl methyl ether/maleic anhydride, salts and hydrolysis products thereof having a K value of from 10 to about 200 and at least one alkali metal salt selected from the group consisting of alkali metal carbonates, alkali metal silicates, and alkali metal borates wherein the ratio of polyvinyl methyl ether/maleic anhydride group member to alkali metal salt group member is, in parts by weight, from 1:100 to 1:2, the ratio of the detergent to the composite builder being, in parts by weight, 8:1 to 1:100, whereby to produce an ecologically desirable detergent composition at least substantially devoid of non-polluting nitrogen and phosphorus.

2. A process according to claim 1 wherein said alkali metal salt is sodium carbonate.