Enzyme-detergent Combination

Abstract

A stable aqueous formulation of an enzyme-detergent combination. The stability of this aqueous formulation permits a wider applicability in laundering textile fabrics.

Parent Case Text

This is a continuation-in-part of application Ser. No. 382, filed Jan. 2, 1970, now abandoned.

Description

This invention relates to the laundering of clothing and, in particular, to a novel enzyme-detergent combination which is notably stable in aqueous formulations.

The laundering of clothing generally is accomplished by means of solid detergent compositions dissolved in a large volume of water. The dirty clothing is immersed in this solution, usually maintained at an elevated temperature, and agitated therein for 10-30 minutes. The so-called "wash water" then is removed and the clothing is rinsed with clean water. Many different types of detergents have been developed for this use and a wide variety are available which produce quite satisfactory results. One exception to these satisfactory results, however, consists of proteinaceous stains. These are removed only with great difficulty and the above laundering process usually is not effective to remove them. Typical proteinaceous stains of this type are those derived from blood, perspiration, albumen, fecal material and the like.

In the prior art, the housewife had to pre-spot any stain on a textile before laundering. Each type of stain had to be treated individually and required a variety of chemicals for different stains, definite operator skill, and much patience to perform a variety of steps. Stain removal or even stain reduction was not always accomplished by these methods.

Combinations of such enzymes and detergents have been used in an effort to solve this problem and these efforts likewise have been successful. It has been necessary to select the detergent and the enzyme very carefully so as to assure compatibility. A wide variety of non-ionic and anionic detergents can be used effectively in combination with these enzymes.

One disadvantage involved in the use of these enzyme-detergent combinations is the fact that a pre-soak period is necessary for stain removal. That is, the stained clothing must be soaked in a solution containing the enzyme-detergent combination for at least 30 minutes prior to subjecting the clothing to the usual laundering cycle. This not only lengthens the overall time required to launder the clothing, but poses a particular problem in view of the fact that most automatic home clothes washers are not adapted to accommodate this extra 30 minutes soaking period. Thus, the housewife must make certain manual adjustments in the operation of the ordinary home washing machine, so that in effect it is not an automatic operation. This is no problem in Europe where the European housewife, through familial habits, has been predisposed to soak her laundry prior to the washing cycle for more active cleaning. In fact, many Europeans routinely soak their family wash overnight to soften and remove stubborn soil and stains prior to washing with a detergent. Required pre-soak periods are built into European washing machine cycles so that the overall washing time is increased up to 30 minutes, which gives the enzyme portion of the formula sufficient contact time to be effective. In the United States, however, it is a problem and it is highly desirable to devise some means by which the housewife can benefit from the effectiveness of enzyme-detergent combinations without, at the same time, rendering her automatic washing machine less convenient to operate and without the extended soaking period.

As noted above, these enzyme-detergent combinations are marketed as solids. The reason for this is that liquid solutions of the enzyme-detergent combinations are not stable. They deteriorate on standing, i.e., the enzyme gradually loses its activity. An aqueous solution of such an enzyme may retain sufficient activity to effectively remove soil and stains for as long as 24 hours, but beyond that, its activity will decrease so that the enzyme solution will no longer effectively remove soil and stains. For this reason, it has been quite impractical to market enzyme-detergent combinations as aqueous solutions, however desirable they would be.

Accordingly, it is an object of this invention to provide a stable aqueous formulation of an enzyme, suitable for use in enzyme-detergent combinations.

Another object of the present invention is to facilitate the use of enzyme-detergent combinations.

Still another object of the present invention is to provide a more convenient means and more complete removal of proteinaceous stains from clothing.

Still another object of the present invention is to provide a stable water solution of an enzyme-detergent combination.

These and other objects of the present invention are accomplished by an aqueous formulation of a protease or a protease amylase enzyme and a polyhydric alcohol, and by such formulations which also contain a detergent.

A method has now been developed to stabilize a water solution of enzyme and detergent that is stable over a long shelf life, is usable as supplied and is very effective in removal of a large number of common stains, such as ground-in dirt, body soil, perspiration, blood, grass stains, milk, coffee, tea and fruit juices. The stability that is achieved is particularly remarkable since the enzyme is present in the formulation in extremely low concentration; in other words, it is very dilute.

The proteases contemplated herein are those detergent compatible enzymes which are active in alkaline to weakly acid media, i.e., those with a minimum pH of 6.0. Acid-active proteases are not used because they are not effective soil and stain removers and in general are not compatible with home laundry detergents. Most of the more effective enzymes have been bacterial in origin although more recently, effective enzymes have been derived from molds and vegetable sources. Those derived from bacteria, however, are preferred. Particularly preferred are those derived from Bacillus subtilus. The concentration of enzyme is within the range of from about 0.001 to about 3.0 weight percent, based on the total aqueous formulation.

In order to determine the proteolytic activity of the alkaline protease herein, the casein digestion test is employed. In this method, 3 ml. of a substrate solution, which contains 1.3 percent casein dissolved in 0.6 percent tris(hydroxymethoyl)aminomethane with the pH adjusted to 7.5, 3 ml. of 0.02N sodium hydroxide and 3 ml. of distilled water are measured into a test tube. This solution is held at 37.degree.C. for 10 minutes and then there is added 3 ml. of a mixture consisting of 8 g. of the enzyme detergent sample and 400 ml. of tris buffer (an aqueous solution of 0.6 percent tris(hydroxymethyl)aminomethane and 0.4 percent sodium chloride, with the pH adjusted to 8.5). Incubate for 15 minutes at 37.degree.C., then add 10 ml. TCA Reagent, which contains 40 percent glacial acetic acid mixed with 1.8 percent trichloroacetic acid and 1.9 percent sodium acetate. Place in 37.degree.C. bath for 15 minutes. The contents of the test tube are then filtered and the optical density of the filtrate is measured at 277 mu. The activity of the sample in PCA units (the initials stand for Proteolytic Activity, Casein Substrate, Alkaline) per gram is calculated by the following formula.

A.sub.277 of hydrolyzate .times. 136/ gram of enzyme prep. in test = PCA units per gram

The protease enzymes referred to herein have an average activity of 165,000 PCA units per gram.

The detergent may be one or a combination of anionic, non-ionic or amphoteric surfactants. Illustrative detergent examples include nonionic surfactants such as polyoxyethylene nonylphenols, polyoxyethylated fatty alcohols, polyoxyethylated fatty acids, glyceryl mono fatty acid esters of 90 percent or higher monoester; anionic surfactants such as the salts of alkyl aryl sulfonates, the salts of the fatty alcohol sulfates, polyoxyalkylene fatty alcohol sulfates and the salts of complex organic phosphate esters; and amphoteric surfactants such as complex fatty compounds containing amide and ester linkages as well as an amine group and an acid group, fatty beta-amino-propionic acids and fatty beta-iminodipropionic acids with the acid portion of the amphoteric molecule as an uncombined acid or as an alkaline metal salt. The detergent or the detergent combination is present in the compositions of this invention within the range of from about 0.05 percent to about 40 percent by weight.

The polyhydric alcohols contemplated herein include those having up to 6 carbon atoms and from 2 to 6 hydroxyl groups, e.g., ethylene glycol, propylene glycol, 1,3-butylene glycol, 1,6-hexylene glycol, d-sorbital dextrose and pentaerythritol; and also the polyalkylene glycols wherein the alkylene group contains up to 6 carbon atoms. Illustrative species of such polyalkylene glycols include polyethylene glycol, polypropylene glycol, polybutylene glycol, polyamylene glycol. The molecular weight of the polyalkylene glycol may range up to about 6,000. The polyhydric alcohol should be water soluble, i.e., at least to the extent of 30 grams in 100 grams of water. Propylene glycol and glycerine are preferred species, although others within this group are similarly effective. The concentration of alcohol is within the range of from about 5 to about 60 percent. Mixtures of these polyhydric alcohols may be used.

As noted above, the pH of the aqueous solution of this invention is a critical feature thereof. The detergent-compatible enzymes contemplated for use in these compositions are effective over a specific pH range. Tests show that the aqueous detergentenzyme solutions of this invention are effective and stable within the pH range of from about 6 to about 9.5. Outside this pH range, these solutions are less effective or ineffective in stain and soil removal or the enzyme is unstable.

The aqueous solutions of this invention may contain other ingredients that are used for their known function. Certain ingredients may be used to adjust the pH of the solution to a value within the specified pH range such as tetrapotassium pyrophosphate, tribasic sodium phosphate, dibasic sodium phosphate, monobasic sodium phosphate, sodium hydroxide or citric acid. Soil suspending agents such as sodium carboxymethyl cellulose or polyvinylpyrrolidone may be optionally incorporated for their known function. Fluorescent whitening agents may be optionally incorporated with those brighteners of the anionic or nonionic types preferred. Perfumes may be employed for their known purpose. Preservatives such as sodium chloride, sodium sulfate, methyl paraben, propyl paraben or potassium sorbate may be used to prevent bacterial inactivation of the enzyme during shelf storage and before use.

An important optional ingredient in the compositions herein is an amylase enzyme. In combination with the protease, it exerts a complementary influence on the soil and stain-removing qualities of the enzyme-detergent combination. Preferred amylases are those derived from Bacillus subtilus.

Another important optional ingredient is an organic solvent such as a naphtha or a chlorinated lower aliphatic hydrocarbon such as perchloroethylene or 1,1,2-trichloroethylene. Chlorinated aliphatic hydrocarbons having fewer than 6 carbon atoms can be incorporated into solutions of this invention with those having 1 or 2 carbon atoms being preferred and their incorporation into the compositions of this invention in concentrations within the range of from about 10 to about 40 percent renders such compositions especially effective in removing oil and grease stains from fabrics in addition to the protein and carbohydrate stains removed by the enzymes. Aqueous compositions containing a chlorinated lower aliphatic hydrocarbon are not solutions, of course, but they nevertheless are useful for the purposes of this invention.

The stability of the aqueous formulations of enzyme and detergent of this invention permits this combination of materials to be stored, transported and marketed as such. They can be used by the housewife who need only apply the aqueous formulation directly to the soiled fabric where it is available in concentrated form to perform its intended function more efficiently than otherwise. An especially significant advantage is the fact that these aqueous formulations can be marketed in aerosol containers from which they may be applied directly to the soiled fabric. This eliminates the necessity for the housewife to get a bucket or pan, fill it with water, add the solid enzyme-detergent combination and wait for it to dissolve, then immerse the soiled fabric in the solution. In addition to aerosol formulations, the enzyme-detergent combinations of this invention may be marketed in liquid form, or in a stick paste form. The holding time is also less than one-half that of the solid enzyme-detergents. In aerosol formulations it is desirable in specific cases to incorporate an anti-foam agent to break the foam quickly after application to a stained surface and thus facilitate penetration of the enzyme and detergent into the stain. Any of various silicone emulsions presently available in the trade are useful for this purpose.

The invention is illustrated by the following specific examples, which are not to be construed as limiting. All parts and percentages herein, unless otherwise expressed, are by weight.

EXAMPLE 1 ______________________________________ PER CENT ______________________________________ Alkaline protease 1.0 Tetrapotassium pyrophosphate 0.2 Propylene glycol 20.0 Water 78.8 EXAMPLE 2 Polyoxyethylene (9-10 units) nonylphenol 10.0 Tetrapotassium pyrophosphate 0.4 Propylene Glycol 10.0 Alkylene Protease 1.0 Water 78.6 EXAMPLE 3 PER CENT Polyoxyethylene (9-10 units) nonylphenol 10.0 Tetrapotassium pyrophosphate 0.4 Glycerin 20.0 Alkaline Protease 1.0 Water 68.6 EXAMPLE 4 Sodium lauryl sulfate 10.0 Propylene Glycol 20.0 Alkaline Protease 1.0 Water 69.0 EXAMPLE 5 Gafac LO-529, a product of GAF Corp., New York, N.Y., believed to be an 88% aqueous solution of the sodium salt of a P.sub.2 O.sub.5 -ethoxylated alkyl phenol reaction product 11.4 Tetrapotassium pyrophosphate 4.0 Propylene Glycol 20.0 Alkaline Protease 1.0 Water 63.6 EXAMPLE 6 Polyoxyethylene (9-10 units) nonylphenyl 35.0 Propylene Glycol 30.0 Methyl paraben 0.1 Propyl paraben 0.05 Tetrapotassium pyrophosphate 0.55 Alkaline protease-amylase 2.0 Anti-foam 0.5 Water 31.8 EXAMPLE 7 PER CENT Polyoxyethylene (10-11 units) nonylphenol 3.50 Polyoxyethylene (30 units) nonylphenol 2.25 Polyoxyethylene (4 units) nonylphenol 2.75 Antaron FC-34, a product of GAF Corp.., New York, N.Y., believed to be a 37% aqueous solution of a sodium alkyl amide sulfonate 4.00 Glyceryl monostearate (90% mono ester) 2.0 Citric Acid 0.09 Propylene Glycol 20.0 Optical Whiteners 0.85 Alkaline Protease 1.0 Water 63.56 EXAMPLE 8 Polyoxyethylene (30 units) nonylphenol 3.83 Polyoxyethylene (4 units) nonylphenol 4.67 Anatron FC-34, a product of GAF Corp., New York, N.Y., believed to be a 37% aqueous solution of a sodium alkyl amide sulfonate 4.0 Glyceryl monostearate (90% mono ester) 2.0 Propylene Glycol 20.0 Citric Acid 0.09 Alkaline Protease 0.5 Water 64.91 EXAMPLE 9 Polyoxyethylene (9-10 units) nonylphenol 10.0 Tetrapotassium pyrophosphate 0.25 Propylene Glycol 20.0 Alkaline Protease 1.0 Perchloroethylene 20.0 Water 48.75 EXAMPLE 10 Polyoxyethylene (30 units) nonylphenol 8.1 Polyoxyethylene (4 units) nonylphenol 9.7 Polyoxyethylene (10-11 units) nonylphenol 12.5 Antaron FC-34, a product of GAF Corp., New York, N.Y., believed to be a 37% aqueous solution of a sodium alkyl amide sulfonate 8.0 Alkaline protease-amylase 2.0 Propylene Glycol 30.0 Potassium Sorbate 1.0 Citric Acid 0.2 Anti-foam 0.5 Water 28.0 ______________________________________

The composition shown in Example 7 was incorporated into an aerosol formulation and applied as a foam to several different stains that had been heavily applied to fabric swatches with the stains derived from a variety of materials. After 30 minutes, the fabric was washed for 15 minutes in one liter of water at 130.degree.F., containing 1.5 grams of Tide, a sodium alkyl sulfonate detergent. The results are shown in the Table below where the cleanliness rating is based on a scale of 1 to 10, with 1 indicating the complete absence of stain and 10 indicating a fabric from which no stain has been removed.

TABLE I __________________________________________________________________________ Treatment with Composition of Ex. 7 Followed Washed With by Detergent Wash Detergent Only __________________________________________________________________________ Stain Cotton Dacron/Cotton Cotton Dacron/Cotton __________________________________________________________________________ Liver 1 1 6 3 Tea 3 1 7 5 Coffee 1 1 5 4 Grape Juice 1 1 2 4 Grease 3 4 8 8 Chocolate 3 1 5 2 Mustard 4 1 8 2 French Dressing 2 1 6 7 Standard Soil Cloth 8 2 5 7 __________________________________________________________________________

From Table I, it is apparent that the enzyme-detergent combination of this invention is effective to remove stains which are not ordinarily removed by the use of detergents alone.

The instability of enzymes in aqueous solutions is well known. Ordinarily, they must be stored in the dry state and then put into solution immediately before use. For required shelf stability, care must be taken so that the final formulation has a moisture content less than 4-5 percent.

The stability of the aqueous solutions of this invention, however, is shown by a comparison of an ordinary enzyme-detergent combination with that same combination supplemented by the addition of 20 percent of propylene glycol. The compared solutions had the following compositions:

Composition A Composition B Alkylphenoxypolyoxyethylene Ethanol 10.0 10.0 Tetrapotassium Pyrophosphate 0.4 0.2 Alkaline Protease (165,000 PCA units) 1.0 1.0 Propylene Glycol -- 20.0 Water 88.6 68.8

After two months' storage Composition A had retained only 24 percent of its enzyme activity, i.e., 396 PCA units per gram of the composition with respect to its original activity of 1650 PCA units per gram, whereas Composition B (illustrative of this invention) after three months, retained 83 percent of its enzymic activity, i.e., 1,369 PCA units per gram with respect to its original activity of 1,650 PCA units per gram.

Cotton and dacron/cotton fabric samples are heavily stained with various types of stains. In each case the stains (on the fabric) are aged for 3 months. The stained cloth is treated with an aerosol formulation of the composition of Example 9, allowed to stand for 15 minutes and then washed for 15 minutes in 1 liter of hot (130.degree.F.) water containing 1.5 grams of a home laundry detergent. The washed samples are rated visually on a scale of 1-10 where 1 indicates complete removal of stain and 10 indicates no removal of stain. A second series of tests are run, for purposes of comparison, with the initial step of treatment with the composition of this invention (product of Example 9) being omitted. The results of these tests are shown below, in Table II.

TABLE II __________________________________________________________________________ Treatment with Composition of Example 9, Followed by Washing with Detergent Washing with Detergent Cotton Dacron/Cotton Cotton Dacron/Cotton __________________________________________________________________________ Liver 2 1 9 9 Blood 1 1 9 9 Tea 3 2 4 4 Coffee 3 2 4 3 Lipstick 2 1 8 8 Chocolate 1 1 2 2 Cocoa 1 1 5 3 Blood-milk-ink (Empa 116) 2 -- 5 -- Cocoa-milk-sugar (Empa 112) 2 -- 4 -- __________________________________________________________________________

While the invention has been described in connection with specific embodiments thereof, it will be understood that it is capable of further modification, and this application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice in the art to which the invention pertains and as may be applied to the essential features hereinbefore set forth, and as fall within the scope of the invention.

Claims

We claim:

1. A stable enzyme-detergent combination comprising an aqueous solution of (a) the equivalent of from about 0.001 percent to about 3.0 percent of a protease having an average activity of 165,000 PCA units per gram (b) from about 0.05 percent to about 40 percent of a detergent and (c) from about 5 to about 60 percent propylene glycol as a stabilizing agent, said aqueous solution having a pH within the range of from about 6.0 to about 9.5.

2. The enzyme-detergent combination of claim 1 wherein the protease is active either in neutral or alkaline media.

3. The enzyme-detergent combination of claim 1 wherein the protease is of bacterial origin.

4. The enzyme-detergent combination of claim 1 wherein the protease is derived from Bacillus subtilus,

5. The enzyme-detergent combination of claim 1 wherein the detergent is a non-ionic detergent.

6. The enzyme-detergent combination of claim 1 wherein the detergent is a polyoxyethylene alkyl phenyl ether.

7. The enzyme-detergent combination of claim 1 wherein the detergent is a polyoxyethylene alkyl phenyl ether having at least 5 oxyethylene units.

8. The enzyme-detergent combination of claim 1 wherein the detergent is an anionic detergent.

9. The enzyme-detergent combination of claim 1 wherein the detergent is a polyoxyalkylene alcohol sulfate.

10. The enzyme-detergent combination of claim 1 wherein the detergent is a metal alkyl benzene sulfonate.

11. The enzyme-detergent combination of claim 1 wherein the detergent is a sodium alkyl benzene sulfonate.

12. The enzyme-detergent combination of claim 1 wherein the detergent is an amphoteric detergent.

13. The enzyme-detergent combination of claim 1 containing additionally an amylase.

14. An aerosol formulation comprising the enzyme-detergent combination of claim 1.

15. A method of cleaning stained textile materials comprising applying to a stained textile material the enzymedetergent combination of claim 1.

16. A stable enzyme-detergent combination consisting essentially of an aqueous solution of (a) the equivalent of from about 0.001 percent to about 3.0 percent of a protease derived from Bacillus subtilus having an average activity of 165,000 PCA units per gram (b) from about 0.05percent to about 40 percent of a non-ionic detergent and (c) from about 5 percent to about 60 percent of propylene glycol, said aqueous solution having a pH within the range of from about 6.0 to about 9.5.

17. An aerosol formulation comprising the enzyme-detergent combination of claim 10.

18. A method of cleaning stained textile materials comprising applying to a stained textile material the enzyme-detergent combination of claim 16.

19. A stable enzyme-detergent combination consisting essentially of an aqueous solution (a) having the equivalent of from about 0.001 percent to about 3.0 percent of a protease derived from Bacillus subtilus and having an average activity of 165,000 PCA units per gram, (b) from about 0.05 percent to about 40 percent of an anionic detergent and (c) from about 5 percent to about 60 percent of propylene glycol, said aqueous solution having a pH of from about 6.0 to about 9.5.

20. An aerosol formulation comprising the enzyme-detergent combination of claim 19.

21. A method of cleaning stained textile materials comprising applying to a stained textile material the enzyme-detergent combination of claim 19.

22. An enzyme-detergent concentrate comprising (a) from about 0.001 percent to about 3.0 percent of a protease, based on an average activity of 165,000 PCA units per gram, (b) from about 0.05 percent to about 40 percent of a detergent and (c) from about 5 percent to about 60 percent of propylene glycol as a stabilizing agent.

23. A stable enzyme-detergent combination comprising water, the equivalent of from about 0.001 percent to about 3.0 percent of a protease having an average activity of 165,000 PCA units per gram, from about 0.05 percent to about 40 percent of a detergent, from about 5 percent to about 60 percent of propylene glycol as a stabilizing agent, and from about 10 percent to about 40 percent of naphtha or a chlorinated aliphatic hydrocarbon having fewer than 6 carbon atoms.