Dry cleaning with enzymes

Enzymes are used in a dry cleaning composition and process. Cleaning compositions comprising lipase, protease and/or amylase enzymes are applied to soiled fabrics in the presence of an organic solvent such as butoxy propoxy propanol to clean the fabrics. In a preferred mode, an enzyme-containing dry cleaning composition is releasably contained in a sheet substrate. The sheet is tumbled with soiled fabrics in a conventional home clothes dryer to clean soiled garments.

 

What is claimed is:

1. A method for cleaning fabrics in a hot air clothes dryer, comprising contacting said fabrics with an integral hydroentangled carrier sheet releasably containing a composition comprising:

(a) at least about 0.001%, by weight, of a detersive enzyme;

(b) from about 1% to about 30%, by weight, of an organic cleaning solvent which is a member selected from the group consisting of the monomethyl-, monoethyl-, monopropyl- and monobutylethers of propoxylated propanol, and mixtures thereof;

(c) at least about 0.01%, by weight, of a polyacrylate emulsifier;

(d) from about 0.05% to about 5%, by weight, of detersive surfactants; and

(e) water.

2. An article for cleaning fabrics in a hot air clothes dryer, comprising an integral hydroentangled carrier sheet releasably containing a composition comprising:

(a) at least about 0.001%, by weight, of a detersive enzyme;

(b) from about 1% to about 30%, by weight, of an organic cleaning solvent which is a member selected from the group consisting of the monomethyl-, monoethyl-, monopropyl- and monobutylethers of propoxylated propanol, and mixtures thereof;

(c) at least about 0.01%, by weight, of a polyacrylate emulsifier;

(d) from about 0.05% to about 5%, by weight, of a detersive surfactant which is a member selected from the group consisting of amine oxides, alkyl ethoxy sulfates, ethoxylated alcohols. ethoxylated alkyl phenols, and mixtures thereof; and

(e) water.

FIELD OF THE INVENTION

The present invention relates to the use of enzymes in dry cleaning processes and compositions which are especially adapted for use in the home.

BACKGROUND OF THE INVENTION

By classical definition, the term "dry cleaning" has been used to describe processes for cleaning textiles using nonaqueous solvents. Dry cleaning is an old art, with solvent cleaning first being recorded in the United Kingdom in the 1860's. Typically, dry cleaning processes are used with garments such as woolens which are subject to shrinkage in aqueous laundering baths, or which are judged to be too valuable or too delicate to subject to aqueous laundering processes. Various hydrocarbon and halocarbon solvents have traditionally been used in dry cleaning processes due to their ability to dissolve and remove oily soils and stains. However, the need to handle and reclaim such solvents has mainly restricted the practice of conventional dry cleaning to commercial establishments.

While solvent-based dry cleaning processes are reasonably effective for removing oily stains from fabrics, they are not optimal for removing particulates such as clay soils, and may require special treatment conditions to remove proteinaceous stains. Traditionally, particulates and proteinaceous stains are removed from fabrics using detersive ingredients and operating conditions which are more akin to aqueous laundering processes than to conventional dry cleaning.

In addition to the cleaning function, dry cleaning also provides important "refreshment" benefits. For example, dry cleaning removes undesirable odors and extraneous matter such as hair and lint from garments, which are then generally folded or pressed to remove wrinkles and restore their original shape. Of course, such refreshment benefits are also afforded by aqueous laundering processes.

As can be seen from the foregoing, and aside from the effects on certain fabrics such as woolens, there are no special, inherent advantages for solvent-based immersion dry cleaning over aqueous cleaning processes with respect to fabric cleaning or refreshment. Moreover, on a per-garment basis, commercial dry cleaning is much more expensive than aqueous cleaning processes.

There has been a continuing search for new, safe and environmentally acceptable solvents for use in dry cleaning. Unfortunately, many such solvents are expensive and, as noted, require a recycling apparatus to provide for their recovery and re-use. In any event, such solvents function merely as a result of their ability to dissolve oily stains, and are thus somewhat limited in their cleaning power.

The present invention employs a novel approach to the dry cleaning operation. Succinctly stated, in the present process enzymes are used to degrade soils and stains, thereby enhancing their removal. For example, while conventional dry cleaning uses only solvents, or solvent/surfactant mixtures, to dissolve or emulsify, and only incompletely remove, stains such as the lipids present in foods, the use of lipase enzymes according to the present invention fragments the lipids into smaller, more soluble molecules, thereby enhancing their likelihood of removal.

Accordingly, it is an object of the present invention to provide dry cleaning compositions and processes which employ enzymes such as lipases, proteases, amylases and mixtures thereof, to degrade lipids, proteinaceous soils and saccharidic soils, respectively. It is another object herein to provide dry cleaning compositions and processes which are suitable for in-home use. It is another object herein to provide non-immersion dry cleaning compositions and processes. These and other objects are secured herein, as will be seen from the following disclosure.

BACKGROUND ART

Dry cleaning processes are disclosed in: EP 429,172A1, published 29.05.91, Leigh, et al.; and in U.S. Pat. No. 5,238,587, issued 8/24/93, Smith, et al. Other references relating to dry cleaning compositions and processes, as well as wrinkle treatments for fabrics, include: GB 1,598,911; and U.S. Pat. Nos. 4,126,563, 3,949,137, 3,593,544, 3,647,354; 3,432,253 and 1,747,324; and German applications 2,021,561 and 2,460,239, 0,208,989 and 4,007,362. Cleaning/pre-spotting compositions and methods are also disclosed, for example, in U.S. Pat. Nos. 5,102,573; 5,041,230; 4,909,962; 4,115,061; 4,886,615; 4,139,475; 4,849,257; 5,112,358; 4,659,496; 4,806,254; 5,213,624; 4,130,392; and 4,395,261. Sheet substrates for use in a laundry dryer are disclosed in Canadian 1,005,204. U.S. Pat. Nos. 3,956,556 and 4,007,300 relate to perforated sheets for fabric conditioning in a clothes dryer. U.S. Pat. No. 4,692,277 discloses the use of 1,2-octanediol in liquid cleaners. See also U.S. Pat. Nos. 3,591,510; 3,737,387; 3,764,544; 3,882,038; 3,907,496; 4,097,397; 4,102,824; 4,336,024; 4,606,842; 4,758,641; 4,797,310; 4,802,997; 4,943,392; 4,966,724; 4,983,317; 5,004,557; 5,062,973; 5,080,822; 5,173,200; EP 0 213 500; EP 0 261 718; G.B. 1,397,475; WO 91/09104; WO 91/13145; WO 93/25654 and Hunt, D. G. and N. H. Morris, "PnB and DPnB Glycol Ethers", HAPPI, April 1989, pp. 78-82.

SUMMARY OF THE INVENTION

The present invention encompasses a dry cleaning and spot removal composition, comprising:

(a) at least about 0.001%, by weight, of a detersive enzyme, especially a lipase, but also members selected from the group consisting of proteases and amylases, and mixtures of such enzymes;

(b) from about 1% to about 30%, by weight, of an organic cleaning solvent;

(c) optionally, at least about 0.01%, by weight, of a polyacrylate emulsifier;

(d) optionally, from about 0.05% to about 5%, by weight, of detersive surfactants; and

(e) water.

The organic solvent used herein is preferably a member selected from the group consisting of butoxy propoxy propanol (BPP; preferred herein), methoxy propoxy propanol (MPP), ethoxy propoxy propanol (EPP), propoxy propoxy propanol (PPP), and mixtures and all isomers thereof, although other solvents may be used. The polyacrylate emulsifier is available commercially from a variety of sources, and preferably has a molecular weight in the range from about 100,000 to about 10,000,000.

The compositions herein optionally can also comprise a detersive surfactant which is preferably a member selected from the group consisting of amine oxides, alkyl ethoxy sulfates, and mixtures thereof. The alkyl ethoxy sulfate surfactants are preferably in their magnesium salt form.

In yet another mode, the compositions herein additionally comprise at least about 0.05%, by weight, of 1,2-octanediol as a highly preferred wetting agent.

The invention also encompasses a method for cleaning fabrics, comprising applying to said fabrics a composition according to the present invention, and especially wherein said method is at least partly conducted in a hot air clothes dryer.

The invention also encompasses an article for cleaning fabrics comprising a carrier, preferably an integral carrier, releasably containing an amount of the cleaning composition herein sufficient to clean a designated load of soiled fabrics, i.e., typically from about 5-50 grams of composition per kilogram of fabrics.

All percentages, ratios and proportions herein are by weight, unless otherwise specified. All documents cited are, in relevant part, incorporated herein by reference.

DETAILED DESCRIPTION OF THE INVENTION

The ingredients of the dry cleaning compositions and their use in the process of the present invention are described seriatim hereinafter.

Cleaning Compositions--The chemical compositions which are used to provide the cleaning function in the present dry cleaning process comprise ingredients which are safe and effective for their intended use. Since the process herein does not involve an aqueous rinse step, the cleaning compositions employ ingredients which do not leave undesirable residues on fabrics when employed in the manner disclosed herein. Moreover, since the process may be carried out in a hot air clothes dryer, the compositions contain only ingredients whose flash points render them safe for such use. The cleaning compositions preferably do contain some water, since water not only aids in the cleaning function, but also can help remove wrinkles and restore fabric drape and appearance, especially in hot air dryers. While conventional laundry detergents are typically formulated to provide good cleaning on cotton and cotton/polyester blend fabrics, the cleaning compositions herein must be formulated to safely and effectively clean and refresh fabrics such as wool, silk, rayon, rayon acetate, and the like.

In addition, the cleaning compositions herein comprise ingredients which are specially selected and formulated to minimize dye removal from the fabrics being cleaned. In this regard, it is recognized that the solvents typically used in immersion dry cleaning processes can remove some portion of certain types of dyes from certain types of fabrics. However, such removal is tolerable in immersion processes since the dye is removed relatively uniformly across the surface of the fabric. In contrast, it has now been determined that high concentrations of certain types of cleaning ingredients at specific sites on fabric surfaces can result in unacceptable localized dye removal. The preferred cleaning compositions herein are formulated to minimize or avoid this problem.

The dye removal attributes of the present cleaning compositions can be compared with art-disclosed cleaners using photographic or photometric measurements, or by means of a simple, but effective, visual grading test. Numerical score units can be assigned to assist in visual grading and to allow for statistical treatment of the data, if desired. Thus, in one such test, a colored garment (typically, silk, which tends to be more susceptible to dye loss than most woolen or rayon substrates) is treated by padding-on cleaner using an absorbent, white paper hand towel. Hand pressure is applied, and the amount of dye which is transferred onto the white towel is assessed visually. Numerical units ranging from: (1) "I think I see a little dye on the towel"; (2) "I know I see some dye on the towel"; (3) I see a lot of dye on the towel"; through (4) "I know I see quite a lot of dye on the towel" are assigned by panelists.

Having due regard to the foregoing considerations, the following illustrates the ingredients used in the cleaning compositions herein, but is not intended to be limiting thereof

(a) Enzyme--The compositions herein comprise enzymes at levels sufficient to provide up to about 5 mg by weight, more typically about 0.001 mg to about 3 mg, of active enzyme per gram of the composition. Stated otherwise, the compositions herein will typically comprise from about 0.001% to about 5%, preferably 0.01%-1% by weight of commercial lipase, protease and amylase enzyme preparations, or mixtures thereof.

(b) Solvent--The compositions will most preferably comprise at least about 4%, typically from about 5% to about 25%, by weight, of the solvent. The objective is to provide at least about 0.4 g, preferably from about 0.5 g to about 2.5 g, of solvent per kg of fabrics being cleaned.

(c) Emulsifier--The compositions will most preferably comprise sufficient polyacrylate emulsifier to provide a stable, homogeneous composition comprising components (a), (b) and (d). For the emulsifiers disclosed herein, levels as low as 0.05%, preferably 0.07% to about 0.20%, by weight are effective. Levels above about 0.2% are unnecessary and are preferably not used, thereby avoiding residues on fabrics.

(d) Water--The compositions will comprise at least about 60%, typically from about 80% to about 95%, by weight, of water. Stated otherwise, the objective is to provide at least about 6 g of water per kg of fabrics being cleaned.

(e) Optionals--The compositions herein may comprise various optional ingredients, including perfumes, conventional surfactants, carriers and the like. If used, such optional ingredients will typically comprise from about 0.1% to about 10%, by weight, of the compositions, having due regard for residues on the cleaned fabrics.

Enzymes are incorporated in the formulations herein to enhance and provide superior fabric cleaning, including removal of protein-based, carbohydrate-based, or lipid (triglyceride-based) stains. The enzymes to be incorporated include lipases, proteases and amylases, as well as mixtures thereof. The enzymes may be of any suitable origin, such as vegetable, animal, bacterial, fungal and yeast origin.

Suitable lipase enzymes for use herein include those produced by microorganisms of the Pseudomonas group, such as Pseudomonas stutzeri ATCC 19.154, as disclosed in British Patent 1,372,034. See also lipases in Japanese Patent Application 53,20487, laid open to public inspection on Feb. 24, 1978. This lipase is available from Amano Pharmaceutical Co. Ltd., Nagoya, Japan, under the trade name Lipase P "Amano," hereinafter referred to as "Amano-P." Other commercial lipases include Amano-CES, lipases ex Chromobacter viscosum, e.g. Chromobacter viscosum var. lipolyticum NRRLB 3673, commercially available from Toyo Jozo Co., Tagata, Japan; and further Chromobacter viscosum lipases from U.S. Biochemical Corp., U.S.A. and Disoynth Co., The Netherlands, and lipases ex Pseudomonas gladioli. The LIPOLASE enzyme derived from Humicola lanuginosa and commercially available from Novo (see also EPO 341,947) is a preferred lipase for use herein.

Suitable protease enzymes are the subtilisins which are obtained from particular strains of B. subtilis and B. licheniforms. Another suitable protease is obtained from a strain of Bacillus, having maximum activity throughout the pH range of 8-12, developed and sold by Novo Industries A/S under the registered trade name ESPERASE. The preparation of this enzyme and analogous enzymes is described in British Patent Specification No. 1,243,784 of Novo. Proteolytic enzymes suitable for removing protein-based stains that are commercially available include those sold under the tradenames ALCALASE and SAVINASE by Novo Industries A/S (Denmark) and MAXATASE by International Bio-Synthetics, Inc. (The Netherlands). Other proteases include Protease A (see European Patent Application 130,756, published Jan. 9, 1985) and Protease B (see European Patent Application Serial No. 87303761.8, filed Apr. 28, 1987, and European Patent Application 130,756, Bott et al, published Jan. 9, 1985). Protease enzymes are usually present in such commercial preparations at levels sufficient to provide from 0.005 to 0.1 Anson units (AU) of activity per gram of composition.

Amylases include, for example, .alpha.-amylases described in British Patent Specification No. 1,296,839 (Novo), RAPIDASE, International Bio-Synthetics, Inc. and TERMAMYL, Novo Industries.

A wide range of suitable enzymes are also disclosed in U.S. Pat. No. 3,553,139, issued Jan. 5, 1971 to McCarty et al. Enzymes are further disclosed in U.S. Pat. No. 4,101,457, Place et al, issued Jul. 18, 1978, and in U.S. Pat. No. 4,507,219, Hughes, issued Mar. 26, 1985; and also in U.S. Pat. 4,261,868, Hora et al, issued Apr. 14, 1981. Enzymes for use in detergents can be stabilized by various techniques. Enzyme stabilization techniques are disclosed and exemplified in U.S. Pat. No. 3,600,319, issued August 17, 1971 to Gedge, et al, and European Patent Application Publication No. 0 199 405, Application No. 86200586.5, published Oct. 29, 1986, Venegas. Enzyme stabilization systems are also described, for example, in U.S. Pat. No. 3,519,570.

The enzymes employed herein can be stabilized by the presence of water-soluble sources of calcium and/or magnesium ions in the finished compositions which provide such ions to the enzymes. (Calcium ions are generally somewhat more effective than magnesium ions and are preferred herein if only one type of cation is being used.) Additional stability can be provided by the presence of various other art-disclosed stabilizers, especially borate species: see Severson, U.S. Pat. No. 4,537,706. Cleaning compositions with stabilized enzymes typically comprise from about 1 to about 30, preferably from about 2 to about 20, more preferably from about 5 to about 15, and most preferably from about 8 to about 12, millimoles of calcium ion per liter of finished composition. This can vary somewhat, depending on the amount of enzyme present and its response to the calcium or magnesium ions. Any water-soluble calcium or magnesium salt can be used as the source of calcium or magnesium ions, including, but not limited to, calcium chloride, calcium sulfate, calcium malate, calcium maleate, calcium hydroxide, calcium formate, and calcium acetate, and the corresponding magnesium salts. A small amount of calcium ion, generally from about 0.05 to about 0.4 millimoles per liter, is often also present in the composition due to calcium in the enzyme slurry and formula water. In some instances, this may be sufficient to provide the desired stability. In any event, the selection and use of the stabilizer is a matter of routine.

In an alternative mode, the enzymes may be "spotted" onto various discrete areas of the carrier used herein. This allows the formulator to improve enzyme stability by isolating individual enzymes from other, potentially de-stabilizing, ingredients which may be present in the cleaning compositions used herein. For example, lipase enzymes may be spotted separately from protease enzymes, etc.

The preferred solvent herein is butoxy propoxy propanol (BPP) which is available in commercial quantities as a mixture of isomers in about equal amounts. The isomers, and mixtures thereof, are all useful herein. The isomer structures are as follows. (The MPP, EPP and PPP solvents also exist as isomers and isomer mixtures, all of which are useful herein.) ##STR1##

BPP is outstanding for cleaning, and is so effective that it allows the amount of the relatively expensive 1,2-octanediol to be minimized. Moreover, it allows for the formulation of effective cleaning compositions herein without the use of conventional surfactants. Importantly, the odor of BPP is of a degree and character that it can be relatively easily masked by conventional perfume ingredients. While BPP is not completely miscible with water and, hence, could negatively impact processing of the cleaning compositions herein, that potential problem has been successfully overcome by means of the PEMULEN-type polyacrylate emulsifiers, in the manner disclosed hereinafter.

It has now been determined that 1,2-octanediol ("OD") affords special advantages in the formulation of the cleaning compositions herein. From the standpoint of aesthetics, OD is a relatively innocuous and low odor material. Moreover, OD appears to volatilize from fabric surfaces without leaving visible residues. This is especially important in a dry cleaning process of the present type which is conducted without a rinse step. From the performance standpoint, OD appears to function both as a solvent for greasy/oily stains and as what might be termed a "pseudo-surfactant" for particulate soils and water-soluble stains. Whatever the physical-chemical reason, OD has now been found to be a superior wetting agent with respect to both cleaning and ease-of-use in the present context of home-use cleaning compositions and processes. If used, OD will typically comprise from about 0.1% to about 1.5% of the cleaning compositions herein.

The BPP solvent used herein is preferably a mixture of the aforesaid isomers. In a preferred mode, the cleaning compositions comprise a mixture of the 1,2-octanediol and BPP, at a weight ratio of OD:BPP in the range of from about 1:250 to about 2:1, preferably from about 1:200 to about 1:5. Similar ratios can be used with the MPP, EPP and PPP solvents.

The highly preferred emulsifier herein is commercially available under the trademark PEMULEN, The B. F. Goodrich Company, and is described in U.S. Pat. Nos. 4,758,641 and 5,004,557, incorporated herein by reference. PEMULEN polymeric emulsifiers are high molecular weight polyacrylic acid polymers. The structure of PEMULEN includes a small portion that is oil-loving (lipophilic) and a large water-loving (hydrophilic) portion. The structure allows PEMULEN to function as a primary oil-in-water emulsifier. The lipophilic portion adsorbs at the oil-water interface, and the hydrophilic portion swells in the water forming a network around the oil droplets to provide emulsion stability. An important advantage for the use of such polyacrylate emulsifiers herein is that cleaning compositions can be prepared which contain solvents or levels of solvents that are otherwise not soluble or readily miscible with water. A further advantage is that effective emulsification can be accomplished using PEMULEN-type emulsifier at extremely low usage levels (0.05-0.2%), thereby minimizing the level of any residue left on fabrics following product usage. For comparison, typically about 3-7% of conventional anionic or nonionic surfactants are required to stabilize oil-in-water emulsions, which increases the likelihood that a residue will be left on the fabrics. Another advantage is that emulsification (processing) can be accomplished effectively at room temperature.

While the cleaning compositions herein function quite well with only the enzyme, the 1,2-octanediol, BPP, PEMULEN and water, they may also optionally contain detersive surfactants to further enhance their cleaning performance. While a wide variety of detersive surfactants such as the C.sub.12 -C.sub.16 alkyl sulfates and alkylbenzene sulfonates, the C.sub.12 -C.sub.16 ethoxylated (EO 0.5-10 avg.) alcohols, the C.sub.12 -C.sub.14 N-methyl glucamides, and the like can be used herein, it is highly preferred to use surfactants which provide high grease/oil removal. Included among such preferred surfactants are the C.sub.12 -C.sub.16 alkyl ethoxy sulfates (AES), especially in their magnesium salt form, and the C.sub.12 -C.sub.16 dimethyl amine oxides. Especially preferred mixtures comprise MGAE.sub.1 S/MgAE.sub.6.5 S/C.sub.12 dimethyl amine oxide, at a weight ratio of about 1:1:1, and MgAE.sub.1 S/C.sub.12 dimethyl amine oxide at a 2:1 weight ratio. If used, such surfactants will typically comprise from about 0.05% to about 2.5%, by weight, of the cleaning compositions herein.

In addition to the preferred solvents and emulsifiers disclosed above, the cleaning compositions herein may comprise various optional ingredients, such as perfumes, preservatives, co-solvents, brighteners, salts for viscosity control, pH adjusters or buffers, anti-static agents, softeners, colorants, mothproofing agents, insect repellents, and the like.

Carrier--When used in a dry cleaning operation, the cleaning compositions are preferably used in combination with a carrier, such that the cleaning composition performs its function as the surfaces of the fabrics being cleaned come in c