US3169071A - Coating composition - Google Patents

Description

r 3,169,071. COATINGCOMPOSITION Harry Hochman, Woodland Hills, Calif.,-assignor tothe United States of America as represented by the SecretaryoftheNavy I No Drawing. Filed June 6, 1961, Ser. 1 Claim. (Cl. 106-15) (Granted under The invention described herein may'be manufactured and used by or for the Government of the United States of America for governmental purposes withoutthe payment of any royalties thereon or therefor.

. This invention relates generally to coating compositions for wooden structures in a marine environment and particularly to hydrocarbon derivatives containing bactericidal or bacteriostatic components. I v

The use of wood for marine structures adjacent to and in the waters of rivers, lakes and oceans extendsfrom antiquityYto the present day; the availability of metalsand concrete notwithstanding. Concomitant with theuse of wood, its marine biological deterioration has been a continuing problem for the same length of time. Unprotected wood in contact with water soon becomes honeycombed with the burrows of marine wood boring animals and itsimininen't' failure is ever present. .A good sized pile. may. be destroyed inas short a time as six months. Treated. wood lasts longer, but "all too often the wood borers somehow gai'n entrance and their destructive ac tivities may begin long beforet he serviceable life of the boat, float, pile, or dock shouldbe ended.

. The extent oftheproblem can be expressd inost dra- Title 35, US. Code (1952), sec. 266) I SW68 atent 3,169,071 Patented Feb. 9, 1965 fresh creosote. When that portion of the pile above the high water markwas examined, the surface creosote was still as toxic as fresh creosote. This evidence shows, conclusively, that in addition to the leaching of some of the preservative from the Wood in the sections below the water line, another mechanism, a toxic destroying or modifying mechanisnn'was' also active in decreasing the effectiveness of creosote below the water line.

I. creosote treated wood. It is believed that it is In all the various harbors investigated, a varying quantity of bacteria have been found that can live on fully the activity ofthesebacteria' which, after a period of time, so alters creosote that itstoxicity to marine boring organisms decreases. It is further-believed that the rate of decrease in toxicity of creosote by the action of these bacteria can be greatly reduced by the incorporation of an effective bactericide or bacteriostatic 'cornpound'in'to the creosote orby impregnating the wood separately by bactericidal compound followed by the standard impregnation with creosote. g i

If the bactericidal or bacteriosjtatic agent is soluble in organic solvents such as creosote, it would be' of advan-- tage to incorporate 'it'intothecreosote anduse the entire solution as a single uriitrfo'r the"impregnation -of-the wood being treated. If the added agent is not soluble in creosote or cannot be successfully compounded therewith to produce a homogeneous fluid, the agent may be impregnatcd into the wood first, using an appropriate solvent as a carrier, and, following this treatment and subsequent drying of the wood, a second impregnation is carried out forcing the creosote into'the wood to the depths desired.

, Obviously, the advantage of using such bactericidal or tar, has been found to be one of the most effective deterrents to such biological infestation, particularly from the standpoint of availability, cost, and ease of application.

Creosote treated wood serves for long periods of time in many habors. In other harbors, however, even creosoted wood has a relatively short service life. In comparatively cold water harbors, creosote treated'piling may last for 30 years or more. In warm water harbors, however, such teatment may not protect the wood for more than a few years. Thus, it has been found that the average service life of creosoted piling in Los Angeles Harbor is about 15 years; Pearl Harbor, Hawaii, 8 years; and at Key West, Florida, about 5 years.

It has been assumed, previously, that creosote loses its effectiveness because it is more readily leached out of the wood in the warm water harbors than it is in the cold water harbors. While it is probably true that leaching does remove a considerable fraction ofthe creosote from the wood after a long period of exposure in a marine en vironment, it has been found that creosote treated wood that has been leached for 12 years in certain warm water harbors is still toxic enough to repel the attacks of marine borers. Since marine borers can destroy a creosoted pile in 5 years and creosote treated wood leached for the equivalent of 12 years isstill toxic to these borers, leaching per se cannot be the sole method, indeed it may not effectiveness.

bacteriostatic agents with creosote is that by controlling the population of creosote tolerant bacteria, the original toxicity of creosote to marine boring organisms is prolonged indefinitely. Should the added agent be of a kind that is also attacked by the environment, it will still prolong the original effectiveness of thecreosote and will decrease the rate by which creosote becomes ineffective. In this manner, the service life of creosoted timbers will be greatly increased even in those bacteria-infested harbors where, heretofore, their surface life has been relatively short.

Among the types of bactericides and bacteriostatic agents that have been found eifective are metal compounds such as copper, zinc, mercury, and silver salts; metalloorganic derivatives such as organic mercuric compounds; triphenylmethane dyes such as malachite green and crystal violet; phenols and halogenated phenols such as pentachlorophenol; quinones such as methyl naphthoquinone; amines such as naphthylamines and acridine; quaternary ammonium compounds such as alkyl trimethyl ammonium and others, some of which will be mentioned hereinafter. It should be noted here that the choice of such bactericides or bacteriostatic agents is limited only by its solubility, toxicity, availability and economy. The most potent agent may not be the most advantageous when these factors are taken into consideration. The design service life of the wooden structure to be built is also an important factor.

In keeping with the philosophy and theory of my invenwhen applied-to wood structures exposed to a marine en-,

vironment by controlling the attacks of creosote tolerant and creosote destroying bacteria, the following efiective preservative methods and materials are setforth:

(1) The Wood is first treated with an aqueous solution of copper sulphate containing between 1 and copper and then, after drying, is impregnated with creosote to standard retentions.

(2) Methyl naphthoquinone is dissolved-in creosote to produce solutions containing between 1 and 10% of the methyl naphthoquinone. The resulting solution is then impregnated into the timbers as a single treatment.

(3) Materials which are insoluble in creosote, such as copper sulphate, can be first converted into a copper chelate or oil soluble salt. This chelate or salt isthen dissolved into the creosote to form a solution containing- 1 to 10% of'copper which solution is used to impregnate as needles.

'Similarly, zinc oxinate was prepared from 4.4 g. (0.02 mole) of zinc acetate in 150 ml. of methanol and 17.5. g. (0.12 mole) of oxine in 175 ml. of methanol.

(4) Another copper salt soluble in creosote may be obtained byconverting copper sulphate to a higher fatty acid salt. Thus, a copper oleate was prepared by dissolving 12.5 g. (0.05 mole) of copper sulphate in 150 ml. of methanol and adding this solution to a solution of 30.0 g. of oleic acid in 750 m1. of methanol. To the resulting solution, an equal volume of water was added with a sufficient quantity of a 10% sodium hydroxide solution to as a blue solid which was then filtered.

(5 Materials which are insoluble in creosote may also emulsify to produce-homogeneous liquids capable of being impregnated in Wood in a single operation. For example, malachite green oxalate is insoluble in creosote. If it is first triturated with an emulsifying agent such as sorbitan trioletate, it can be. r'ea'dily'mcorporated into creosote. Thus, if a 1% solution of malachite green in creosote is desired,- 1 g. of malachite green oxalate is triturated with 0.1 to 5' g. of sorbitan .trioleate and then added to 100 ml. of creosote. p

Having thus described my invention; its practice, and

the formulation of various bactericidalv and bacteriostatic agents that may be employed therewith, I do not intend to be limited thereby except as suchlimitations may be for creosote-tolerant, creosote-attacking bacteria, said composition consisting of -99% creosote and 1-.l0.%-

bactericidal agent selected, from the group consisting of creosote soluble zinc oxinate, malachite. green oxalate,

and malachite green oxalate after trituration withsorbitan trioleate, an emulsifying agent.

References Cited by the Examiner UNITED STATES PATENTS 1,690,390 11/28 Williams et a1. 106-15 2,296,401v 9/42 Perkins 10615 2,561,380 '7/51 Kalberg loo-15X 3,065,087

11/62 Goldstein et a1. 106- 15 MORRIS LIEBMAN, Primary Examiner.

JOSEPH REBOLD, ALEXANDER H. BRODMERKEL,

Examiners.