EP0188545B1

EP0188545B1 - Trisodium phosphate/sodium hydroxide/sodium hypochlorite composition and process for removing stains

Info

Publication number: EP0188545B1
Application number: EP19850903594
Authority: EP
Inventors: Donald P. Molony
Original assignee: Individual
Current assignee: Individual
Priority date: 1984-07-05
Filing date: 1985-07-03
Publication date: 1989-10-25
Also published as: AU4603285A; EP0188545A1; EP0188545A4; DE3573930D1; WO1986000635A1

Abstract

A composition and process for removing stains from fabric. The composition comprises a solution of trisodium phosphate, sodium hydroxide, and sodium hypochlorite. The process comprises the steps of (a) contacting stained fabric with a composition comprising an aqueous solution of trisodium phosphate, sodium hydroxide and sodium hypochlorite; (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 trisodium phosphate-containing 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 wihtout ill effect to the fabric or the hands of the user.

Description

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 at 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 alkali metal phosphate (e.g., trisodium phosphate) for use as a grease-cutting detergent. Krusius acknowledges 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 compostiion which is effective in removing grease (hyrophobic) stains would be highly effective in removing proteinaceous (hydrophilic) stains as well.
Accordingly, there is a need for an effective non-enzymatic composition for removing protein-containing stains such as set blood stains from fabrics.
The present invention provides a composition for removing stains from fabric characterised in that the said composition comprises an aqueous solution containing from 1.0 to 15.0 grams per liter of trisodium phosphate, from 0.5 to 10.0 grams per liter of sodium hydroxide and from 1.0 to 4.0 percent by weight of sodium hypochlorite based on active chlorine content.
The composition of the invention is effective in substantially completely removing even set blood stains from even certain delicate fabrics without undesirable effects associated with enzymatic detergents.
According to a further aspect of the present invention there is provided a process for removing stains from fabric comprising (a) contacting stained fabric with an aqueous solution comprising a composition in accordance with the invention; (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 trisodium phosphate-containing 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 10.5 grams per liter of sodium hydroxide, and between about 1.0 and about 4.0 percent by weight of sodium hypochlorite based on active chlorine content; (b) allowing the solution to remain in contact with the fabric for a period of less than about 2 minutes; and rinsing the fabric in water to dilute and substantially completely remove the trisodium phosphate-containing solution.
The preferred compositions of the invention are effective in removing from fabrics stains including set blood stains in a manner which is effective, convenient, and inexpensive. Moreover, the present compositions can remove virtually completely 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. A further advantage of the preferred compositions of the invention is that the compositions are nonenzymatic and leave no chemical residue on fabric.
Trisodium phosphate (tertiary sodium orthophosphate, tribasic sodium phosphate) is easily produced by methods well known in the art. In one embodiment, soda ash (Na₂C0₃) is mixed with phosphoric acid (H₃P0₄) 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 (NasPO- 12H₂0) but which are also available in anhydrous form. The hydrated and anhydrous forms are equally suitable for the process of the present invention.
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% Na₂0); rayon (containing iron, copper, and manganese); 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 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.
In a preferred embodiment, lavender 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) trisodium phosphate, and between about 0.5 and 10.0 grams sodium hydroxide; dissolving in combination in 250 to 500 ml of water; and 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.
In a preferred embodiment, between about 8.0 and 12.0 grams of trisodium phosphate and between about 4.0 and 6.0 g sodium hydroxide 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 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 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, 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. Otherwise, as much as six (6) minutes may be required to remove stains to the same extent normally removable in two (2) minutes.
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, and fruit. 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 less than about two minutes, and preferably between 10 and 45 seconds, and more preferably between 15 and 30 seconds. If the composition is left in contact with the fabric for longer than about five minutes, certain fabrics may be damaged (i.e., may show a decrease in tensile strength), and the stain may become set, and resist further treatment. If contact occurs for substantially less than 5 seconds, the treatment may be ineffective.
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 susb- tantially remove the trisodium phosphate-containing solution from the fabric and prevent harm to 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 invention as a prewash treatment.
With the exception of natural silk and wool, virtually any type of fabric may be treated in accordance with the present invention without damage to the fabric. For example, natural fabrics including cotton, and synthetic fabrics including nylon, rayon, Orlon (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 consequences. 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 therein 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.

Example 1

The following composition was prepared as a solution:
The composition was sprayed onto a 50% cotton/50% polyester blend which had blood stains set by laundering and allowed to remain for approximately 30 seconds. After rinsing, the stain was visually undetectable.

Examples 2-6

The procedure of Example 1 was substantially followed, except that the following fabrics stained with fresh blood were used, and were soaked for the following periods of time:
With silk, discoloration ("burning") became apparent after 50 seconds. In each of the other cases, after rinsing, the stain was virtually undetectable.

Comparative Examples A-D

7.5 g of sodium hydroxide was dissolved in 1000 ml of water and the procedure of Example 1 substantially followed on the following fabrics for each of the following periods of time; except that fresh blood was used:
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 mls of water.
Woolite (trademark of Boyle-Midway, Inc. for a phosphate-free detergent containing organic surfactants)
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, Iric. for a detergent containing sodium carbonate)
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.

Claims

1. A composition for removing stains from fabric characterised in that the said composition comprises an aqueous solution containing from 1.0 to 15.0 grams per liter of trisodium phosphate, from 0.5 to 10.0 grams per liter of sodium hydroxide and from 1.0 to 4.0 percent by weight of sodium hypochlorite based on active chlorine content.

2. A composition according to claim 1, wherein the aqueous solution contains from 8.0 to 12.0 grams per liter of trisodium phosphate, from 4.0 to 6.0 grams per liter of sodium hydroxide, and from 3.0 to 4.0 percent by weight of sodium hypochlorite based on active chlorine content.

3. A composition according to claim 2, comprising about 10.0 grams per liter of trisodium phosphate; about 5.0 grams per liter of sodium hydroxide; and about 3.5 percent by weight of sodium hypochlorite based on active chlorine content.

4. A process for removing stains from fabric comprising (a) contacting stained fabric with an aqueous solution of a composition as claimed in any one of the preceding claims; (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.

5. A process according to claim 4, wherein the fabric from which stains are removed is cotton, linen, synthetic fibers, or blends thereof.

6. A process according to claim 4 or 5, wherein the stains which may be removed are blood, serum, mucous, and/or perspiration.

7. A process according to claim 4, 5 or 6, further comprising the step of laundering the fabric after rinsing.

8. A process according to any one of claims 4 to 7, wherein the aqueous solution remains in contact with the fabric for a period of time of less than about 2 minutes.

9. A process according to claim 8, wherein the aqueous solution remains in contact with the fabric for a period of time of from 10 to 45 seconds.