US3443010A - Composition and methods for rendering absorbent materials fungicidal comprising an aqueous solution of borax/and the bis(tri-n-propyltin) diammonium chloride of a tri-polyoxyethylated n-alkyl trimethylene diamine - Google Patents

Description

United States Patent Olfice US. Cl. 424-148 3 Claims ABSTRACT OF THE DISCLOSURE Method for rendering absorbent materials such as wood fungicidal by impregnation with an aqueous solution of borax and the bis(tri-n-propyltin) diammonium chloride of a tri-polyoxyethylated N-alkyltrimethylene diamine.

The present invention relates to methods for treating absorbent substrates to inhibit the growth of mold fungi thereon, and to the treating agents used. The invention relates particularly to the anti-fungal treatment of wood.

Copending application Ser. No. 422,033 filed Dec. 29, 1964, now US. Patent 3,346,607 granted Oct. 10, 1967, of which this application is a continuation-in-part, teaches certain fungicidal quaternary ammonium compounds containing tin. The compounds, which are formed by the reaction of a trialkyl tin halide with a tertiary amine, have the formula RI! [R'-l ISn(R) ]+X HzCHzO) ,H wherein X is a halide ion (fluoride, chloride, bromide, or iodide) and R is lower alkyl. To form the compounds, an inorgano tin halide, (R) SnX, wherein R and X have been defined, are reacted with an amine wherein: (A) R is a long chain fatty hydrocarbon, R" is (CH CH O) H, and x+y is about 10; (B) R is a long chain fatty hydrocarbon, R" is (CH CH O) H and x+z is about 50; (C) R' is a long chain fatty hydrocarbon, R" is CHzCH CHnN CHQGHZmuH and xi-l-m +n is about 10; (D) wherein R is a long chain fatty hydrocarbon, R" is H2O HzCHz-N-Sl1(R) a X- H2CH20)u x+p+q is about 10, and R is lower alkyl; and (E) wherein R is -(CH CH O),H, R" is Riv -CHgCHzCH2N (CH'zCHzOhH x+r+s is about 10, and R" is a long chain fatty hydrocarbon.

As disclosed in said copending application, the quaternary ammonium compounds are highly soluble in water, which facilitates their application to absorbent materials 3,443,010 Patented May 6, 1969 from solution. Because they are in salt form, they appear to be much more tenaciously held to treated substrates such as wood than are electrically neutral compounds, and thus are of particular usefulness for the treatment of materials used for the packaging of food, where transfer of the fungicidal material from the package to its contents is preferably minimized.

Although the fungicidal and germicidal activities of the compounds of the copending application are as good or better than those of any materials heretofore known in the art for the treatment of wood, it has now been discovered that the fungicidal activity of those compounds can be surprisingly increased by employing them in combination with an inorganic boron compound such as borax, boric acid, or buffer solutions comprising boric acid in combination with a soluble borate. Although borax has been used in the past as an anti-fungal agent, particularly in the treatment of wood, it has heretofore been believed that fungus control with the material was due to the creation of an alkaline pH unfavorable to the growth of fungi. In the present invention, however, it has been found that boron containing compounds used in conjunction with the organotin quaternary ammonium salts already discussed show fungicidal activity not only in alkaline solutions, such as of borax, but also in acidic boric acid solutions and in acid, neutral and alkaline buffer solutions of boric acid and a borate.

More surprisingly, the fungicidal effects observed when treating a substrate with an organotin compound in combination with an inorganic boron compound are not merely additive, but show an unexpected enhanced activity greater than the combined activities of the individual components when used alone. That is, synergism is observed.

This synergism is observed when the tin compounds of the invention are combined with even fairly small amounts of a material such as borax, boric acid, or boric acid/ borate buffers, e.g. in aqueous solution with amounts as small as 1 percent by weight of the boron compound. As additional boron compound is added to such aqueous solutions, improvement in fungicidal activity is observed, and extremely efiicient fungicides are obtained when the content of boron compound is about 3.5 percent by weight of the solution. Although larger amounts of boron compound, e.g. up to saturation (usually about 5 percent), can be employed without harm, this is economically wasteful and does not substantially improve the degree of fungicidal activity over that observed at lower concentrations of about 3.5 percent. In the aqueous treating solutions, the tin compound is suitably present in concentrations of from about 0.04 percent by weight to about 0.2 percent by weight, preferably about -0.1 percent by weight, the latter corresponding roughly to a concentration of one ounce per ten gallons of water.

The solutions just described are used to impregnate an absorbent material to which fungicidal properties are to be imparted, commonly wood but also including cardboard, paper, textiles, etc. The solutions are effective when used with all types of woods, wet or dry, but are of particular utility for the treatment of soft woods such as pine used in the-construction of wirebound boxes for packaging produce and other foodstuffs. Because of the need for flexibility in soft wood slats used in such wirebound boxes, the slats usually contain a high water content and are highly susceptible to attack by fungi which cause an undesirable discoloration of the wood.

A better understanding of the present invention and of its many advantages will be had by referring to the following example, given by way of illustration.

EXAMPLE Pine slats, 23% inches long by 4% inches wide and /8 inch thick, were cut with a back-roll on a rotary lathe.

Groups of fifty slats were selected at random and submerged individually for a period of fifteen seconds in treating solutions of a composition indicated below in Table I. A control group of fifty slats was left untreated. Each group of slats was then. bulk piled on a wooden pallet in the random fashion typical of production handling. The pallet of slats was stored at mill conditions for a period of five weeks, and hence was exposed to airborne spores present in the mill. The proportion of the total surface area of each slat on which mold fungi had developed was then estimated visually, as reported in the following Table. In the tests reported below, the organotin compound in each case is the bis(tri-n-propyltin) diammonium chloride of a tri-polyoxyethylated N- alkyltrimethylene diamine, i.e. the compound wherein R' is a long chain fatty hydrocarbon and x+p+q is about 10.

polyoxyethylated N-alkyl trimethylene diamine of the formula (CHzCHzOhH (CH OHzOMH [RNCHzCH CHzN-Sn(C;H1)al 201- SD(C3H7)3 H2CH2O)QH wherein R is a long chain fatty hydrocarbon and x+17+q is about 10.

2. The method as in claim 1 wherein said absorbent substrate is wood.

3. A composition adaptable to the treatment of absorbent substrates to render them fungicidal, said composition being an aqueous solution of borax in an amount from about 0.5 percent by weight to about 3.5 percent by weight and about 0.1 percent by weight of the bis(trin-propyltin) diammonium chloride of a tri-polyoxyethylated N-alkyl trimethylene diamine of the formula wherein R is a long chain fatty hydrocarbon and x+p+q is about 10.

TABLE I Percent of slots covered by mold fungi to the extend ot- Treating solution 75-100% 50-75% 25-50% 5-25% 15% 1% Control 39 50 4 7 0.5% borax 56 43 1 3.42% borax..- 44 51 1 4 Organotin compound (1 oz./10 gal. .086%) 4 11 27 58 Organotin compound (1 oz./10 ga1.)+1.0% boric 3 12 37 39 o ziiiiiir'iri'blifid'fi Hi/l'tigiY-i-d '5 136k 12 31 52 Oianotin eomgound (1oz ./gal .)+3:42 7;, horas .1: 100

Comparable results are observed when employing buf- References Cited fered mixtures comprising boric acid and soluble borate UNITED STATES PATENTS salts such as the alkali metal borates to give treating 2,041,655 5 1936 G 16 solution havlng a mildly alkaline, mildly acid, or neutral 2 268 387 151941 1:3 n 1 pH. For example, boric acid/borax mixtures 1n which the 2317:9555 8/1950 Bacon 167 38.5 weight ratio of acid to Salt is 011 have 3 P 0f Y 3 307 039 5 19 2 Mazur 2 429 7 reducing the ratio to 10:1, 5:1, or 2:1, buffer solutions 3,305,442 2/1967 Nishimoto 167 386 respectively having a pH of 7.20, 7.50, or 7.90 can be prepared.

What is claimed is:

1. The method of treating an absorbent substrate to render it fungicidal which comprises impregnating said substrate with an aqueous solution comprising borax in an amount from about 0.5 percent by Weight to about 3.5 percent by weight and about 0.1 percent by Weight of the bis(tri-n-propyltin) diammonium chloride of a tri- OTHER REFERENCES FRANK CACCLAPAGLIA, 111., Primary Examiner.

S. J. FRIEDMAN, Assistant Examiner.

US. Cl. X.R.