WO1988005462A1

WO1988005462A1 - Trisodium phosphate/sodium hydroxide/sodium hypochlorite/buffer composition and process for removing stains

Info

Publication number: WO1988005462A1
Application number: PCT/US1988/000139
Authority: WO
Inventors: Donald P. Molony
Original assignee: Molony Donald P
Priority date: 1987-01-23
Filing date: 1988-01-25
Publication date: 1988-07-28

Abstract

A composition and process for removing stains from fabric. The composition comprises a solution of trisodium phosphate, sodium hydroxide, sodium hypochlorite, and a buffer. The process comprises the steps of (a) contacting stained fabric with a composition comprising an aqueous solution of trisodium phosphate, sodium hydroxide, sodium hypochlorite, and a buffer; (b) allowing the solution to remain in contact with the fabric for a period of time sufficient to substantially completely remove any stain; and (c) rinsing the fabric in water to dilute and substantially remove the solution. The composition and process of the invention are highly effective in removing set blood, mucous and perspiration as well as other protein stains from a variety of fabric types without ill effect to the fabric or the hands of the user.

Description

TRISODIUM PHOSPHATE/SODIUM HYDROXIDE/SODIUM HYPOCHLORITE/BUFFER COMPOSITION AND PROCESS FOR

REMOVING STAINS

BACKGROUND OF THE INVENTION

The present invention relates to a composition and process for removing stains from fabric.

Protein-containing stains in fabric present a difficult laundry problem. Blood presents a particular problem in that it contains a number of difficult-to- remove components, including iron and a variety of complex proteins. If blood becomes set in a fabric, such as by laundering the fabric or neglecting to treat the stain immediately, the stain may resist known laundering treatments, and garments or other stained articles may have to be discarded.

Typically, enzyme-containing detergents are employed to remove blood stains. For example, U.S. Patent No. 3,553,139 to McCarty et al discloses a composition containing an enzyme, a peroxy compound and a mixture of builder salts and organic detergents. The composition is stated to be effective in removing blood and other stains from fabrics and textiles. However, several disadvantages are associated with use of enzymatic detergents. Enzymes, particularly in combination with peroxy compounds, tend to be harsh both to the fabric and to the hands of the user, and may even elicit an allergic reaction. Further, enzymes, which are themselves proteinaceous, may be inactivated in the presence of peroxy compounds or at extremes of pH. Finally, enzymes are a relatively high cost component of detergents, thus increasing the cost of manufacturing the detergent. It is also known to use trisodium phosphate in heavy-duty cleaning compositions. For example, U.S. Patent No. 3,360,476 to Krusius discloses a liquid composition comprising 3 to 12 parts by weight of an

SUBSTITUTE SHEET alkali metal phosphate (e.g., trisodium phosphate) for use as a grease-cutting detergent. Krusius acknow¬ ledges that the composition is expected to be harsh on the hands, and therefore teaches the addition of an emollient.

Further, U.S. Patent No. 1,870,804 to Gale et al discloses a composition comprising a double salt of trisodium phosphate and sodium metaborate which is used to remove grease and dirt on citrus fruit. It would not be expected that a composition which is effective in removing grease (hydrophobic) stains would be highly effective in removing proteinaceous (hydrophilic) stains as well.

OBJECTS AND SUMMARY OF THE INVENTION

It is an object of the present invention to formulate a composition which is effective in removing stains including set blood stains from fabrics.

It is a further object of the invention to virtually completely remove stains including set blood stains in a manner which is effective, convenient, and inexpensive.

It is a still further object of the invention to virtually completely remove set blood stains or stains from other proteins from fabric in a manner which is neither harmful nor harsh on the fabric or the hands of the user.

It is a still further object of the invention to virtually completely remove blood stains utilizing a nonenzymatic and economical composition which leaves no chemical residue on fabric.

The present invention is a composition for removing stains from fabric comprising an aqueous solu¬ tion of trisodium phosphate, sodium hydroxide, sodium

SUBSTITUTESHEET hypochlorite, and a buffer. The composition is effective in substantially completely removing even set blood stains from even certain delicate fabrics without undesirable effects associated with enzymatic detergents.

In another embodiment, the invention relates to a process for removing stains from fabric comprising (a) contacting stained fabric with an aqueous solution comprising trisodium phosphate, sodium hydroxide, sodium hypochlorite and a buffer; (b) allowing the solution to remain in contact with the fabric for a period of time sufficient to substantially completely remove any stain; and (c) rinsing the fabric in water to dilute and substantially remove the solution.

DETAILED DESCRIPTION OF THE INVENTION As stated above, in its broadest sense, the present invention is a composition for removing stains from fabric comprising an aqueous solution of trisodium phosphate, sodium hydroxide, sodium hypochlorite, and a buffer. The composition is effective in substantially completely removing even set blood stains from even certain delicate fabrics without undesirable effects associated with enzymatic detergents. In a more specific embodiment, the invention relates to a composition for removing stains which is an aqueous solution comprising between about 1.0 and 15.0 grams per liter of trisodium phosphate, between about 0.5 and 10.0 grams per liter of sodium hydroxide, between about 1.0 and 4.0 percent by weight of sodium hypochlorite, based on active chlorine content, and a buffer to maintain a pH of between about 10 and about 12, preferably between about 10 and about 11. As is also stated above, in the broadest sense of another embodiment of the present embodiment, the invention relates to a process for removing stains from fabric comprising (a) contacting stained fabric with a solution comprising trisodium phosphate, sodium hydroxide, sodium hypochlorite, and a buffer; (b) allowing the solution to remain in contact with the fabric for a period of time sufficient to substantially completely remove any stain; and (c) rinsing the fabric in water to dilute and substantially remove the solution.

In a more specific embodiment, the invention relates to a process for removing stains from fabric comprising (a) contacting stained fabric with a solution comprising between about 1.0 and 15.0 grams per liter of trisodium phosphate, between about 0.5 and 10.0 grams per liter of sodium hydroxide, between about 1.0 and about 4.0 percent by weight of sodium hypochlorite based on active chlorine content, and between about 0.25 and 10.0 percent by weight of sodium carbonate, sodium bicarbonate, or a mixture thereof;

(b) allowing the solution to remain in contact with the fabric for a period of less than about 10 minutes; and

(c) rinsing the fabric in water to dilute and substantially completely remove the solution.

Trisodium phosphate (tertiary sodium ortho- phosphate, tribasic sodium phosphate) is easily produced by methods well known in the art. In one embodiment, soda ash (Na₂C0₃) is mixed with phosphoric acid (N3PO4) in a molar ratio of 3:2 to form disodium phosphate. The disodium phosphate is then mixed with caustic soda (NaOH) to form trisodium phosphate which is recoverable as colorless crystals which are usually hydrated (Na₃P04*12H₂O) but which are also available in

TESHEET anhydrous form. The hydrated and anhydrous forms are equally suitable for the process of the present inven¬ tion.

The second component, sodium hydroxide, is readily available commercially and any commercially available grade or variety is suitable for use in the present invention, including reagent grade, granulated (containing 60% to 76% Na 0) ; and solution (50% or 73% sodium hydroxide) . Sodium hypochlorite is most commonly produced by electrolyzing a cold, dilute solution of salt water (e.g., sea water). Addition of sodium hydroxide, as in the present invention, confers additional stability to the solution. In a preferred embodiment, sodium hypochlorite is supplied in an aqueous solution comprising about 2 to 10% by weight based on active chlorine sodium hypochlorite (i.e., between about 1.0 and 6.0 grams per liter available chlorine). In a more preferred embodiment, the hypochlorite solution contains about 5.25% sodium hypochlorite, by weight based on active chlorine content (about 3 grams per liter) , the remainder of the composition comprising water and other inert ingredients. By "active chlorine content" is meant available chlorine concentration. Another preferred method of forming the composition of the present invention is to add chlorine to a cold dilute solution of sodium hydroxide. Hypochlorite obtained in this manner may have as much as 0.8% by weight sodium hydroxide in solution, thereby avoiding the need to separately add sodium hydroxide after the other ingredients are combined.

Reference has been made above to a buffer comprising sodium carbonate, sodium bicarbonate, or a mixture thereof. While these are preferred, any buffer

SUBSTITUTE SHEET which will maintain the pH between about 10 and 12 can be employed, provided it does not adversely effect the other ingredients of the composition. Preferably, the pH is maintained below about 11, since above that value, the possibility of damage to fabric increases. A pH below about 10 should be avoided, since the stability of the sodium hypochlorite will be adversely effected.

It is preferred that the buffer system employed hold the pH as close to pH 10 as possible consistent with effective stain removal to provide a product which is more gentle to skin and fabric than a higher pH. Those skilled in the art will be aware of various other buffer systems useful in the practice of the present invention.

Sodium carbonate and sodium bicarbonate are well known for use in water softening and to buffer the pH of solutions to a level which is gentle to skin and fabric. However, it is surprising that a salt which is gentle enough for internal human consumption could enhance the performance of the strong oxidizer employed in the present invention.

Sodium carbonate and sodium bicarbonate are readily available commercially. Sodium carbonate is available from natural deposits as well as being synthetically produced by the Solvay process. Sodium bicarbonate is produced by treating a saturated solution of sodium carbonate with carbon dioxide. Sodium sesquicarbonate, which is produced by crystallization of a solution containing equimolar quantities of sodium carbonate and sodium bicarbonate, can also be employed in the composition of the present invention.

SUBSTITUTESHEET When added alone, sodium carbonate acts as a buffer by forming carbonic acid in the presence of water and sodium hydroxide. Thus, the addition of greater amounts of sodium carbonate will continue to lower the pH until a pH of about 10.4 is reached. In the case of sodium bicarbonate, care must be exercised to not add an amount which lowers the pH below about pH 10, due to the release of hydrogen ion in aqueous solution. Addition of sodium sesquicarbonate will affect pH roughly in the same manner as the addition of a simple mixture of sodium carbonate and sodium bicarbonate.

In a preferred embodiment, the composition also includes a suitable surfactant to improve wetting and penetration of the composition of the present invention into the fabric, and to solubilize a fragrance, if employed. The surfactant can be any surfactant which is stable in the presence of sodium hypochlorite. Several such surfactants are well known to those skilled in the art. Examples of such surfactants are alkyl sulfates, betaines, alkyl benzene sulfonates, and disulfonated diphenyl oxides. A particularly preferred group of surfactants are those sold under the trademark DOWFAX by Dow Chemical Company of Midland, Michigan. Among the DOWFAX surfactants, DOWFAX 2A1 (sodium dodecyl diphenyloxide disulfonate) and DOWFAX XDS 8390.00 (C₁₆ alpha-olefin disulfonate) are particularly preferred. The surfactant is typically added at between about 0.1 and 5.0% by weight.

In a preferred embodiment, fragrance oil is added as a perfuming agent.

In one embodiment, a solution is prepared by combining between 1.0 and 15.0 grams (dry weight)

SUBSTITUTE SHEET trisodium phosphate, and between about 0.5 and 10.0 grams sodium hydroxide; dissolving the combination in 250 to 500 ml of water; adding the resulting solution to 500 to 750 ml of a 5.25% solution of sodium hypochlorite to produce a total volume of one liter, and then adding a solution of buffer to maintain the pH at about 10.

In a preferred embodiment, between about 8.0 and 12.0 grams of trisodium phosphate, between about 4.0 and 6.0 g sodium hydroxide, and between about 8.0 and 12 grams of sodium carbonate are dissolved in approximately 250 to 400 ml of water, and 600 to 750 ml of a 5.25% solution of sodium hypochlorite is added to produce a volume of one liter. In a most preferred embodiment, approximately 10.0 g of trisodium phosphate, approximately 10.0 g of sodium carbonate, and approximately 5.0 grams of sodium hydroxide are dissolved in approximately 330 ml of water and approximately 670 ml of a 5.25% solution of sodium hypochlorite added to bring the volume to one liter.

The ingredients may be mixed simply by pouring the specified proportions of trisodium phosphate, sodium hydroxide, sodium carbonate, and sodium hypochlorite into a suitable container, e.g., of glass, ceramic, etc, and adding water to bring the volume to the specified amount. Agitation may be employed to assist mixing.

The composition may be applied topically to the stained fabric in a number of ways. It is envisioned that any known method for applying a small quantity of a solution to a surface may be employed. In preferred embodiments, the solution may be applied as a spray in a non-aerosol pump, rolled or brush on,

SUBSTITUTESHEET or dabbed onto the fabric through an absorbent fabric (e.g., felt) stopper or sponge.

To maintain the activity of the solution, it is important to avoid contact with any metallic material during mixing and storage.

Stains which may be removed in accordance with the present invention include fresh or set blood or serum stains (including menstrual blood stains) ; fresh or set perspiration, mucous, pus or any other body exudates; wine, stains from flowers and stems of plants, mildew, rust, ball point pens, fabric dye, fruit, chocolate, tea, coffee, and fruit, synthetic, and vegetable dyes. By "set" is meant stains which become difficult to remove either by the passage of time (oxidation process) or by laundering (e.g., at temperatures over about 55°C) . By "set blood stains" is meant stains which have become brownish in color.

The composition is to remain in contact with the stained fabric for a period of time necessary to remove the stain completely, which is usually between

30 seconds and 10 minutes. To obtain the maximum stain removal, it is preferred that fabric be soaked in the composition of the present invention.

Following contact with the solution, the fabric is rinsed, preferably in cold water, to remove the trisodium phosphate-containing solution. The temperature of the water may be between 35°C and 55°C, and preferably between 40"C and 50°C. This rinsing step is necessary to dilute and substantially remove the solution from the fabric. Optimally, after rinsing, the fabric is laundered according to the manufacturer's specifications (by hand or machine washing) to restore softness to the fabric and for sanitation reasons. In a preferred embodiment, it is envisioned to employ the solution of the.present inven¬ tion as a prewash treatment.

With the exception of natural silk and wool, virtually any type of fabric may be treated in accord- ance with the present invention without damage to the fabric. For example, natural fabrics including cotton, and synthetic fabrics including nylon, rayon, Orion (trademark of E.I. duPont de Nemours for an acrylic fiber), Dacron (trademark of E.I. duPont de Nemours for polyethylene terephthalate) , and various polyesters and blends thereof may be treated without harmful conse¬ quences. Silk and wool, however, will begin to be burned and/or dissolve on exposure to the solution of the present invention after about five seconds of contact. It is also noted that the solution may be used in direct contact with the hands, which is totally unexpected, in that sodium hydroxide alone in the concentrations employed herein is extremely burning to the hands. The composition and process of the present invention are suitable for use in removing stains in garments, linens, hospital gowns, and upholstery, as well as any item containing either natural or synthetic fibers, with the exception of silk and wool. The following examples are offered by way of illustration and are not to be construed as limitative to the scope of the application.

SUBSTITUTESHEET Example 1

The following composition was prepared as a solution:

Trisodium phosphate 10.0 g

Sodium carbonate 10.0 g

Sodium hydroxide 5.0 g Sodium hypochlorite (5.25%) . . 670 ml water q.s to 1 liter

The composition was applied to a 50% cotton/50% polyester blend which had blood stains set by laundering and allowed to remain in contact with the fabric for approximately 30 seconds. After rinsing, the stain was visually undetectable.

Example 2

The following composition was prepared as a solution:

Trisodium phosphate 10.0 g Sodium carbonate 10.0 g

Sodium hydroxide 5.0 g

Sodium hypochlorite (5.25%) . . . . 670 ml

DOWFAX 2A1 2.0 g water q.s to 1 liter

Examples 3-9

The following fabrics were soaked in the composition of Example 1 for approximately the following periods of time:

Wool 60 seconds

Silk 60 seconds

Rayon 60 seconds

Nylon 60 seconds

Cotton 60 seconds Dacron 60 seconds

Polyester 60 seconds

With silk, discoloration ("burning") became apparent after about 50 seconds. In each of the other cases, the fabric was found to be undamaged.

Comparative Examples A-D

7.5 g of sodium hydroxide was dissolved in 1000 ml of water and the procedure of Example 1 sub¬ stantially followed on the following fabrics for each of the following periods of time, except that fresh blood was used:

Cotton 60 seconds

Wool 60 seconds

Silk 60 seconds

Nylon 60 seconds

Cotton/polyester 60 seconds

SUBSTITUTESHEET In the case of silk and wool, discoloration was again apparent after about 15 seconds. In each of the other cases, the stain became set by the treatment (i.e., turned from red to dark brown).

Comparative Examples E-K

A set blood stained fabric was contacted with each of the following aqueous solutions in a manner identical to the procedure of Example 1. In each case, the contact occurred for 30 minutes.

Sodium hypochlorite (5.25% solution) Sodium hydroxide (7.5 g/liter)

Calcium chloride (100 g/liter)

Calcium hypochlorite (100 g/liter)

Soda ash (100 g/liter)

Calcium carbonate (100 g/liter) Sodium carbonate (7.5 g/liter)

In each case, upon rinsing the stain had appeared to "set" in the fabric (turned from red to dark brown) and was resistant to further treatments to remove the stain.

Comparative Examples L-X

A set blood-stained fabric was contacted for 30 minutes with a solution prepared by dissolving 2.5 g of each of the following in 250 mis of water.

Woolite (trademark of Boyle-Midway, Inc. for a phosphate-free detergent containing organic surfactants) .

SUBSTITUTE SHEET Woolite Gentle Cycle (trademark of Boyle

Midway, Inc. for a phosphate-free detergent containing alkyl aryl sodium sulfonate) . Snowy Bleach (trademark of Gold Seal Co. for a detergent containing sodium perborate and sodium carbonate) . Clorox 2 (trademark of The Clorox Company for a phosphate-free detergent containing sodium carbonate, sodium metaborate, and a protease) .

Diaperpur (trademark of Boyle-Midway, Inc. for a detergent containing sodium carbo nate) . Biz (trademark of Procter & Gamble for an enzyme-containing detergent) .

Axion (trademark of Colgate-Palmolive Co. for an enzyme-containing detergent) . Borateem (trademark of U.S. Borax & Chemical

Corp. for a detergent containing borax and brighteners) .

Calgon (trademark of Beecham Products for a detergent containing sodium phosphate and sodium carbonate) . hydrogen peroxide (3%) . sodium perborate. oxalic acid. Miraq (trademark of Minnetonka Corp. for a detergent containing tripolyphosphate, nonylphenol, and sodium carbonate) .

In each case, after rinsing, the stain appeared virtually unchanged by the treatment.

SUBSTITUTESHEET While the above description provides a full and complete disclosure of the preferred embodiments of the invention, various modifications, alternative constructions, equivalents and improvements may be practiced without departing from the scope of the invention and of the appended claims. Accordingly, the above description and illustrations should not be construed as limiting the scope of the invention as defined by the appended claims.

SUBSTITUTE SHEET

Claims

1. A composition for removing stains from fabric comprising an aqueous solution of trisodium phosphate, sodium hydroxide, sodium hypochlorite, and a buffer.

2. The composition of Claim 1 wherein the aqueous solution contains between about 1.0 and 15.0 grams per liter of trisodium phosphate, between about 0.5 and 10.0 grams per liter of sodium hydroxide, between about 1.0 and 4.0 percent by result of sodium hypochlorite based on active chlorine content, and between about 0.25 and 10.0 percent by weight of sodium carbonate, sodium bicarbonate, or a mixture thereof.

3. The composition of Claim 1, wherein the aqueous solution contains between about 8.0 and 12.0 grams per liter of trisodium phosphate, between about 4.0 and 6.0 grams per liter of sodium hydroxide, between about 8.0 and 12 grams per liter of sodium carbonate, and between about 3.0 and 4.0 percent by weight of sodium hypochlorite based on active chlorine content.

4. The composition of Claim 1, comprising about 10.0 grams per liter of trisodium phosphate; about 5.0 grams per liter of sodium hydroxide; about 10.0 grams of sodium carbonate; and about 3.5 percent by weight of sodium hypochlorite based on active chlorine content.

SUBSTITUTESHEET

5. The composition of Claim 1,. further comprising a sodium hypochlorite-stable surfactant.

6. The composition of Claim 5, wherein the surfactant is an alkyl sulfate, betaine, alkyl benzene sulfonate, or disulfonated diphenyl oxide.

7. The composition of Claim 5, wherein the surfactant is present at between about 0.1 and 5.0% by weight.

8. A process for removing stains from fabric comprising (a) contacting stained fabric with a solu¬ tion comprising an aqueous solution of trisodium phosphate, sodium hydroxide, sodium hypochlorite, and a buffer; (b) allowing the solution to remain in contact with the fabric for a period of time sufficient to substantially completely remove any stain; and (c) rinsing the fabric in water to dilute and substantially completely remove the trisodium phosphate-containing solution.

9. The process of Claim 8, wherein the fabric from which stains are removed is selected from the group consisting of cotton, linen, synthetic fibers, and blends thereof.

10. The process of Claim 8, wherein the stains which may be removed are selected from the group consisting of blood, serum, mucous, and perspiration.

11. The process of Claim 8, further compris¬ ing the step of laundering the fabric after rinsing.

SUBSTITUTE SHEET

12. The process of Claim 8, wherein the aqueous solution remains in contact with the fabric for a period of time of less than about 10 minutes.

13. The process of Claim 8, wherein the aqueous solution remains in contact with the fabric for a period of time between about 10 seconds and 2 minutes.

14. The process of Claim 8, wherein the composition of (a) comprises an aqueous solution of between about 1.0 and 15.0 grams per liter of trisodium phosphate; between about 0.5 and 10.0 grams per liter of sodium hydroxide; and between 1.0 and 4.0 percent by weight sodium hypochlorite based on active chlorine content; and between about 0.25 and 10.0 percent by weight of sodium carbonate, sodium bicarbonate, or a mixture thereof.

15. The process of Claim 8, wherein the composition of (a) comprises an aqueous solution of between about 8.0 and 12.0 grams per liter of trisodium phosphate, between about 4.0 and 6.0 grams per liter of sodium hydroxide, between about 8.0 and 12.0 grams per liter of sodium carbonate, and between about 3.0 and 4.0 percent by weight of sodium hypochlorite based on active chlorine content.

16. The process of Claim 14, wherein the aqueous solution remains in contact with the fabric for a period of time of less than about 10 minutes.

SUBSTITUTESHEET

17. The process of Claim 14, wherein the aqueous solution remains in contact with the fabric for a period of time between about 10 seconds and 2 minutes.

18. The process of Claim 8, wherein the composition of (a) comprises an aqueous solution of about 10.0 grams per liter of trisodium phosphate; about 5.0 grams per liter of sodium hydroxide; and about 10.0 grams of sodium carbonate about 3.5 percent by weight of sodium hypochlorite based on active chlorine content.

19. The process of Claim 8, wherein the composition of (a) further comprises a sodium hypochlorite-stable surfactant.

20. The process of Claim 19, wherein the surfactant is an alkyl sulfate, betaine, alkyl benzene sulfonate, or disulfonated diphenyl oxide.

21. The process of Claim 19, wherein the surfactant is present at between about 0.1 and 5.0% by weight.

SUBSTITUTE SHEET