US3413399A - Water-repellent and preservative composition and method of use - Google Patents

Description

United States Patent 3,413,399 WATER-REPELLENT AND PRESERVATIVE COMPOSITION AND METHOD OF USE Donald Clifford Wehner, Stamford, Conn., assignor to American Cyanamid Company, Stamford, Conn., a corporation of Maine No Drawing. Filed Nov. 23, 1965, Ser. No. 509,406 6 Claims. (Cl. 424-131) ABSTRACT OF THE DISCLOSURE A water-repellent and preservative mixture, for application to textiles and cellulose products, of an aluminum or zirconium salt and the terephthalic, isophthalic or malic acid salt of an alkyl guanidine.

This invention relates to compositions and methods for preserving porous substrates from microbial deterioration and for imparting water-repellency thereto,

By porous substrates is meant formed textile materials and cellulose products which are subject to microbial attack and which are receptive to water-repellent finishes containing aluminum or zirconium salts. Water repellency is here distinguished from waterproofing in that the former quality results from deposition of a hydrophobic substance on the fibers composing the textile material or cellulose product, leaving the interstices between the fibers substantially unfilled and unaltered. As a result, air and water vapor can pass through the textile material or cellulose product. In contrast a waterproofed substrate is one in which a continuous film of the hydrophobic substance is applied to the substrate so as to render it impervious in either the liquid or vapor phase. The degree of water-repellency is dependent on the arrangement and closeness of the fibers in the textile material or cellulose product as well as on the efficiency of the water-repellent.

By textile material is meant formed fibers or fabric, either woven or felted containing wool, cotton, silk, synthetics or blends of two or more of these types. The cotton may be in the form of regenerated cellulose, linen, jute, ramie, hemp and the like. The synthetics include known materials such as rayon, nylon, cellulose acetate, polyesters, acrylics, as well as modifications and blends thereof.

By cellulose products is meant paper, cardboard, and various cellulose building or construction materials such as fiberboard and the like which are exposed to moisture and therefore subject to water and microbial damage.

Such textiles and cellulose products may take any shape, size or form and are articles which are intended to be re-used. Specific illustrations of such articles would include wearing apparel, handkerchiefs, diapers, dish and bath towels, books and book covers, washable cloth toys, dolls and similar playthings, hospital and hotel sheets and pillowcases, hospital and examination room bathrobes and slippers, barbers and beauticians cloths, and similar articles.

A major objective in the manufacture of textile materials and cellulose products is to provide not only a finish which is water-repellent but also one which inhibits the growth of microorganisms or is toxic to microorganisms attracted to or residing on the porous substrate. The presence of these microorganisms often results in the harmful condition called mildew, rotting, and other forms of decomposition, and promotes displeasing odor. These microorganisms include a wide variety of fungi and bacteria and their growth is particularly promoted in textile and cellulosic materials worn close to the body such as sweat shirts and diapers and in tenting, cordage,

Patented Nov. 26, 1968 awning and other fabrics exposed to high moisture and humidity.

Compositions containing antimicrobial agents should be active at low concentration against a broad spectrum of microorganisms. Moreover, they should be non-toxic and non-allergenic to the touch. Furthermore, if applied to a textile material, the composition should be substantially resistant to leaching out under home and commercial laundering conditions and should impart little or no modification of the hand of the textile.

A known class of compounds exhibiting high activity in low concentrations against a wide variety of microorganisms is represented by the formula (RNH( l-NH2)11-A (I) wherein A represents an acidic salt forming group, n is the small whole number 1 or 2, and R is an alkyl radical containing from about 8 to 18 carbon atoms, straight or branched chain, but preferably straight chain of from about 10 to 14 carbon atoms. These compounds are also characterized as the acid or normal salts of alkyl guanidines. Numerous acids, both organic and inorganic as well as monobasic and polybasic, have been employed to form the salts. Such acids have included for example sulfuric, hydrochloric, nitric, phosphoric, acidic, propionic, butyric, malic, phthalic, benzoic, boric, and the like, as further described with application in US. Patents 2,906,595, 2,867,562, and 2,921,881.

Although providing anti-microbial activity in other environments, the compounds represented by the above formula are surprisingly not uniformly effective as a class when applied to porous substrates in combination with a water-repellent material containing an aluminum or zirconium salt. Thus certain members, e.g., the alkyl guanidine sulfates and 2-ethyl hexanoates, either are too insoluble for contact with harmful microorganisms or have such extreme water solubility, e.g., the alkyl guanidine acetates and hydrochlorides, as to be easily washed out during laundering or cleaning. Moreover, of those limited number of compounds providing the proper solubility for contact with the harmful microorganisms while avoiding leaching out, it has surprisingly been discovered that only a certain few maintain their activity when contacted with a water-repellent material containing an aluminum or zirconium salt. While not fully understood, it appears that when an alkyl guanidine salt having a free carboxyl group is employed, e.g., phthalic acid or phthalic anhydride salt of n-dodecyl guanidine, the free acid group reacts in some manner with the aluminum or zirconium salt in the waterrepellent, thereby rendering the alkyl guanidine salts inactive.

Accordingly, effective water-repellency and antimicrobial activity is provided by a composition which comprises a water-repellent mate-rial containing an aluminum or zirconium salt and an antimicrobial compound of the formula wherein R is alkyl as defined above and A is a dicarboxylic acid selected from the group consisting of terephthalic acid, isophthalic acid and malic acid. The salts represented by the above formula are not rendered inactive by the aluminum or zirconium salts commonly employed in or as water-repellents, exhibit high levels of toxicity in low concentrations, and have the proper solubility for contact with microorganisms while also providing resistance to leaching out.

The aluminum or zirconium salts are any of the wellknown compounds employed as water-repellent agents.

These include aluminum sulfate (alum), aluminum acetate, aluminum formate, zirconium oxychloride, zirconium oxynitrate, zirconium acetate, and ammonium zirconium dicarbonate.

In the past, these salts have provided a deg-rec of waterrepellency when applied alone or when generated in situ (as by reaction of aluminum oxide or zirconium oxide with acetic or formic acid) on a porous substrate. In time, however, wate-r-repellency of textiles was improved by combining the aluminum or zirconium salt treatment with an alkali metal soap process, thereby providing a complex insoluble hydrophobic metal soap on or within the porous substrate. Later, water-repellency of textiles was further improved by combining the aluminum of zirconium salt treatment, alone or with an alkali metal soap, with an application of a parafiin wax or wax-like material such as silicone or perfluorocarbon resins. These materials are applied either in a two-bath process or, preferably, in a single bath.

Best results by oneor two-bath applications depend on the preparation of a stable wax emulsion. This is provided, in the case of one-bath processes for imparting water-repellency to textiles, by addition of known and commercially available protective colloids such as gelatin, fish glue, bone glue, de-acetylated chitin, hydrolysed bovine blood albumin, polyvinyl alcohol, and sodium polyacrylate. Numerous surface-active agents are also employed with or as substitutes for the foregoing watersoluble macromolecules. These include pOlyethenOxy compounds, e.g., ethylene oxide adduct with N-hydroxyethyl-N-octadecylaniline, ethylene oxide-oleic acid adducts, non-ionics such as a mannitan fatty ester, cationics such as stearoxyethyldimethylbenzylammonium chloride, and combinations of cationics and non-ionics.

It is also conventional to employ in such compositions diluents and solvents such as mineral spirits, nonyl phenol, animal or vegetable oils, and other organic and inorganic liquids.

In the case of cellulose products such as paper and cardboard, the process of imparting water-repellency is commonly inherent to the sizing operation. Among the numerous known sizing methods which also impart waterrepellency may be mentioned preparation of a rosin or paraffin wax dispersion and at the appropriate moment precipitating the rosin or wax onto the fibers by addition of an aluminum or zirconium salt, most often aluminum sulfate -alum), in quantity sufficient to provide a pH of 4 to 5.

The foregoing treatments suffer from the same defi ciency as textiles when it is desired to preserve the substrate by application of an alkyl guanidine salt as an antimicrobial agent. The instant invention obviates this difficulty in substantially the same fashion as already described, i.e., by employing the alkyl guanidine salts of Formula II above which, surprisingly, are not rendered inactive by the aluminum or zirconium salts conventionally employed as precipitating and water-repellent agents in the treatment of cellulose products.

A particularly preferred example of one-bath compositions is the so-called acid/wax combination. This is an emulsion containing as essential ingredients the aluminum or zirconium salt, a wax, and a protective colloid such as gelatin. The emulsion is stabilized by maintaining an acid pH, generally in the range of about 2 to 6 but preferably or less. The acidity is often provided by addition of a mineral or organic acid such as acetic acid. Typically such dispersions are made by adding alum to a solution of alkali metal soap in the presence of gelatin or fish glue. The aluminum salt should be present in a stoichiometric excess over the soap. The wax is generally a hydrocarbon wax and may contain a high melting wax such as ceresin. The aluminum salt is usually aluminum acetate or aluminum formate and the zirconium salt is usually the oxichloride or the acetate. Sometimes the aluminum or zirconium salt is formed in situ by an admixture of aluminum oxide or zirconium oxide with acetic or formic acid. For example, one commercial composition comprises 17% paraflin wax, 2.5% bone glue, 3.0% A1 0 7.0% formic acid, 0.7% wood rosin, 0.2% potassium hydroxide and sufiicient Water to make 100%. The wax can be added molten or as -a preformed emulsion.

From the foregoing, it will be evident that the present invention contemplates and includes compositions comprising any of the above aluminum salts or zirconium salts and an alkyl guanidine salt of Formula II above, as dry, aqueous, or non-aqueous solutions or dispersions, as well as such compositions containing additional ingredients Which do not substantially interfere with the water-repellent and antimicrobial properties of the two essential ingredients.

In accordance with the method of the invention the aluminum or zirconium salt water-repellent material and antimicrobial agent are applied in admixture or separately to the porous substrate by any convenient means such as dipping, padding, spraying, exhaustion, or the like, for a period of time suflicient to fix the composition onto the substrate.

The total amounts of aluminum or zirconium salt and alkyl guanidine salt should be sufiicient to provide both water repellency and antimicrobial activity. Proportions and total amounts may be varied over wide ranges depending, for example, on the thickness of the substrate and the duration of effectiveness required for the particular use for which the treated substrate is intended. As a general rule, good antimicrobial activity results when the substrate contains from about 0.01% to 5% of the antimicrobial agent based on the weight of dry substrate. If the substrate is a textile material, the preferred range of antimicrobial compound is from about 0.25% to 0.5% based on the weight of dry fabric. When the aluminum or zirconium salt and alkyl guanidine salt are applied from an admixture, such dispersions typically comprise up to about 40% total solids of which the proportion of aluminum or zirconium salt to alkyl guanidine salt will range from about 1:10 to 10:1.

The literature on the subject of water-repellency of porous substrates including textile materials and cellulose products is extensive. A fairly comprehensive treatment is Waterproofing and Water-Repellency, I. L. Moilliet, Editor, Elsevier Publishing Co., New York, 1963, particularly Chapters 3, 6, 7, 8 and 11. This text is incorporated herein by reference.

The following examples further illustrate the invention but are not limitative thereof except as indicated in the appended claims. All parts and percentages are by weight unless otherwise specified.

Example 1 To demonstrate the utility of alkyl guanidine salts as fabric preservatives, a series of cloth samples x 80 cotton percale) were treated with several salts of n-dodecyl guanidine and then subjected to a soil-burial test as described in Method 5762, Mildew Resistance of Cloth; Soil Burial Method of Federal Specification CCC-T-19l, Textile Test Methods. In accordance with this specifica tion, the cloth strips were treated with 0.5% and 0.25% (based on weight of dry fabric) of n-dodecyl guanidine hydrochloride, n-dodecyl guanidine acetate, n-dodecyl guanidine acid phthalate, n-dodecyl guanidine terephthal ate, and n-dodecyl guanidine 2-ethylhexanoate by dissolving the toxicant in isopropanol and padding the solution onto the cloth samples. After drying, the cloth samples were buried in soil for six weeks The cloth samples were thereafter removed and examined for deterioration. Untreated cloth samples and those treated with n-dodecyl guanidine hydrochloride, n-dodecyl guanidine acetate, and n-dodecyl guanidine Z-ethylhexauoate were found to be so completely rotted that they could not be handled without disintegrating. The 0.5% level samples of n-dodecyl guanidine acid phthalate and n-dodecyl guanidine terephthalate by visual inspection appeared to be unaffected by the burial while at the lower concentration of each, 0.25%, disintegration of the cloth sample was only partial. As a positive control one sample of cloth was treated with 0.1% of copper 8-hydroxyquinolinolate (a well-known fabric fungicide). This sample showed deterioration intermediate that resulting from the two concentrations of n-dodecyl guanidine acid phthalate and n-dodecyl guanidine terephthalate.

Example 2 In another series of similar tests, separate samples of awning material (cotton duck) were treated with n-dode-' cyl guandine acid phthalate and n-dodecyl guanidine terephthalate to give concentrations of 0.4% based on weight of dry fabric. The toxicants were applied from a commercially available acid/wax emulsion which contained an aluminum soap. Upon completion of the burial period, it was found that the n-dodecyl guanidine terephthalate-treated cloth had retained almost all of its original tensile strength whereas the sample treated with n-dodecyl guanidine acid phthalate had lost almost as much strength as the untreated control (almost total disintegration). In efforts to determine why n-dodecyl guanidine acid phthalate provided good protection when used alone but failed when in combination with an acid/wax waterproofing agent it was found that the n-dodecyl guanidine acid phthalate formed an intractable precipitate with aluminum acetate (present as a complex aluminum soap in the acid/ wax mixture) when heated whereas n-dodecyl guanidine terephthalate was not effected by such mixing.

Example 3 In another soil burial test conducted as described in Examples 1 and 2 with n-dodecylguanidine malate as the antimicrobial agent in an acid/Wax emulsion of substantially the same composition as described in Example 2, good Water-repellency and resistance to rotting was noted. Moreover, this salt and n-dodecylguanidine isophthalate were not found to precipitate when separately admixed with aluminum acetate, thereby demonstrating that toxicity is not lost by reaction with aluminum salt water-repellents.

Iclaim:

1. A water-repellent and preservative composition which comprises a water-repellent compound selected from the group consisting of aluminum and Zirconium salts and an antimicrobial compound of the formula wherein R is a straight-chain alkyl containing from about 10 to 14 carbon atoms and A is selected from the group consisting of terephthalic acid and isophthalic aicd and wherein the proportion of said water-repellent compound to said antimicrobial compound is in the range of from about 1: 10 to 10: 1.

2. The composition of claim 1 wherein A of the formula is terephthalic acid.

3. The composition of claim 1 wherein A of the formula is isophthalic acid.

4. A method of imparting both Water-repellency and resistance to microbial deterioration to a member of the group consisting of paper, cardboard, fiberboard and formed textile materials which comprises applying thereto an effective amount of a water-repellent and preservative composition as defined in claim 1.

5. The method of claim 4 wherein A of the formula is terephthalic acid.

6. The method of claim 4 wherein A of the formula is isophthalic acid.

References Cited UNITED STATES PATENTS 2,713,008 7/1955 Schulenbury 117138.5 2,789,956 4/1957 Eder 117-135.5 2,906,595 9/ 1959 Pelcak 167-22 2,921,881 1/1960 Lamb l67306 3,031,335 4/1962 Segal 117135.5

ALBERT T. MEYERS, Primary Examiner.

S. I. FRIEDMAN, Assistant Examiner.