DE69005468T2 - Wood treatment against juice staining. - Google Patents

Abstract

The use is disclosed of one or more of (a) a polyquaternary compound, (b) a thickening agent or dispersing agent, (c) a nonionic surfactant having from 3 to 12 alkylene oxide, preferably ethylene oxide, units, (d) a simple quaternary compound in an amount at least equal to the amount of isothiazolone in the solution, to prevent stripping of isothiazolone in an isothiazolone-containing solution used as an anti-sapstain agent in wood treatment, where the solution is recurrently contacted with wood.

Description

This invention relates to an agent against sap discoloration in the treatment of wood.

Freshly felled wood contains large amounts of fungal nutrients such as sugars. These, together with high moisture content, make wood extremely susceptible to blue discoloration and attack by mold. To protect wood against such fungal discoloration, the wood is usually sprayed or dipped in a preservative, these preservatives containing as an active ingredient a fungicidal isothiazolone such as "Kathon 893" sold by Rohm and Haas Company. However, when wood is dipped in solutions of isothiazolone fungicides, it has been observed that the wood preferentially absorbs the isothiazolone from the treatment mixture, so that the concentration of the isothiazolone in the mixture drops very quickly. This results in the wood first dipped or sprayed taking up excess isothiazolone from the freshly prepared treatment mixture, whereas wood treated with previously used mixture takes up too little isothiazolone from the mixture, as it is already depleted of isothiazolone. It would therefore certainly be advantageous if the uptake of isothiazolone from the mixture by wood was substantially the same as that of the other components of the mixture, so that the concentration of isothiazolone in the mixture would remain substantially the same during uptake.

It is already known to use polymers to thicken wood treatment solutions in order to increase the absorption of boron-containing wood preservatives by increasing the adhesion of the solution to the wood surface.

However, we have now surprisingly found that by adding certain additives to wood treatments against sap discoloration, the expulsion or stripping of the isothiazolone from the mixture can be significantly reduced or actually eliminated, which is in contrast to the experience with previous treatment of wood.

The invention therefore relates in a first embodiment to the use of an isothiazolone-containing solution of one or more of

(a) a polyquaternary compound based on either polyamine or polyamine ether, polyvinylpyrrolidone, polyquaternary ammonium polymer or cationic copolymer based on acrylates,

(b) a water-soluble and/or water-dispersible polymer containing either homopolymer(s) or copolymer(s) of (meth)acrylic acid(s) and/or ester(s), vinyl homopolymer(s) and/or copolymer(s) and/or polymer(s) based on glycol monomer(s) or ether monomer(s)

(c) a non-ionic surfactant having 3 to 12 alkylene oxide units, preferably ethylene oxide units,

(d) a simple quaternary compound containing ammonium halide(s) of the formula

in which Ph is C₆H₅ or C₆H₄R, R is hydrogen or (C₁-C₃)alkyl, R² is (C₁-C₃)alkyl, R' (C₈-C₁₈)alkyl and X is halogen in a ratio to isothiazolone of 1:1 to 5:1, preferably 3.5:1, as an agent for controlling the expulsion of the isothiazolone from the solution when it is to be used as a wood treatment agent against sap discoloration on repeated contact with wood.

It is readily apparent to the person skilled in the art that this anti-stripping agent (hereinafter referred to as "additive") should be selected in such a way that it has no adverse effect on the wood, on the isothiazolone or other components that may be present in the mixture used in the invention. To explain what is meant by an adverse effect on the wood, for example, in the case of wood that is subsequently intended for painting, an additive should be used that has no adverse effect on the paintability of the wood. Taking these considerations into account, it is not difficult for the person skilled in the art to select appropriate additives.

Preferred polyquaternary compounds for incorporation into the anti-discoloration mixtures according to the invention are

(1) ‘Gafquat 755N’, a quaternary copolymer of vinylpyrrolidone and dimethylaminoethyl methacrylate,

(2) "Polyquart H81", a condensation resin of polyamine/polyglycol and

(3) “Rhoplex LE 1126”, a cationic ethyl acrylate polymer.

Suitable non-ionic surfactants are the following substances:

(1) Polyalkoxylates of alkylphenols, alcohols, amines and alkanolamides and

(2) Block polymers of ethylene and propylene oxide.

The ratio of isothiazolone to additive may depend, among other things, on the molecular weight of the additive; for example, a minimum ratio of isothiazolone to additive of 1:3.5 has been found necessary in some cases, so this is a preferred endpoint for the above ratio.

The resulting anti-juice stain compositions are generally in the form of a mixture for dipping or spraying containing from 0.005 to 3%, preferably from 0.05 to 1.5%, more preferably from 0.075 to 1%, and most preferably from 0.1 to 0.5% by weight of isothiazolone. Alternatively, the compositions may be in the form of a concentrate containing from 1 to 80%, usually from 10 to 40% by weight of isothiazolone and which can be converted at the point of use into treatment mixtures containing the aforementioned level of isothiazolone.

Suitable isothiazolones are any isothiazolones described as suitable or preferred in the following patents of Rohm and Haas, such as GB 1 474 983, GB 1 390 443, GB 1 488 891, GB 1 575 226, US 4 325 201, US 4 322 475, EP 0 095 907, US 3 870 795, US 4 396 413, US 3 761 488, US 4 067 878, US 3 755 224, US 3 801 575, US 3 849 430, US 3 887 352, US 4 031 055, US 4 105 431, US 4 129 448, US 4 062 946. Isothiazolones with a low solubility in water are preferred. Such isothiazolones have the general formula

in which Y may be (C₁-C₁₈)alkyl or (C₃-C₁₂)cycloalkyl, each of which may be substituted by one or more hydroxy, halogen, cyano, alkylamino, dialkylamine, arylamino, carboxy, carbalkoxy, alkoxy, alkylthio, arylthio, haloalkoxy, cycloalkylamino, carbamoxy or isothiazolonyl; an unsubstituted or halogen-substituted (C₂-C₈)-alkenyl or alkynyl; a (C₇-C₁₀)-aralkyl optionally substituted by one or more halogen, (C₁-C₄)-alkyl or (C₁-C₄)-alkoxy; and an aryl optionally substituted with one or more halogen, nitro, (C₁-C₄)alkyl, (C₁-C₄)alkylacylamino, carb(C₁-C₄)alkoxy or sulfamyl; and R' and R² are independently H, halogen or (C₁-C₄)alkyl.

Substituents for Y are generally substituted or unsubstituted C₁-C₁₈ alkyl or C₃-C₁₂ cycloalkyl; R² is preferably H, Me or Cl; and R' is preferably H or Cl. Representative substituents of this type are methyl, ethyl, propyl, isopropyl, butyl, hexyl, octyl, cyclohexyl, benzyl, 3,4-dichlorobenzyl, 4-methoxybenzyl, 3,4-dichlorophenyl, 4-methoxyphenyl, hydroxymethyl, chloromethyl, chloropropyl, hydrogen and the like.

As is well known, such isothiazolones are usually protected against degradation by the presence of various stabilizers. Some of them are described in the aforementioned patents. Other suitable stabilizers and isothiazolones are disclosed in the following patents: EP-A-0 166 611, EP-A-0 194 146 and European Application 88 310 390.5.

Particularly preferred isothiazolones are:

4,5-dichloro-2-n-octyl-3-isothiazolone, 4,5-dichloro-2-cyclohexyl-3-isothiazolone and particularly preferably 2-n-octyl-3-isothiazolone, 5-chloro-2-methyl-3-isothiazolone and also 2-methyl-3-isothiazolone.

The isothiazolones used in the invention can be in any form, including microemulsions as described in the pending European patent application 88 307 123.5.

Another embodiment of the invention is directed to a method for preventing the loss of isothiazolone from an isothiazolone-containing solution upon repeated contact with wood as a wood treatment agent against sap discoloration by introducing into the solution one or more of

(a) a polyquaternary compound based on either polyamine or polyamine ether, polyvinylpyrrolidone, polyquaternary ammonium polymer or cationic copolymer based on acrylates,

(b) a water-soluble and/or water-dispersible polymer containing either homopolymer(s) or copolymer(s) of (meth)acrylic acid(s) and/or ester(s), vinyl homopolymer(s) and/or copolymer(s) and/or polymer(s) based on glycol monomer(s) or ether monomer(s),

(c) a non-ionic surfactant having 3 to 12 alkylene oxide units, preferably ethylene oxide units,

(d) a simple quaternary compound containing ammonium halide(s) of the formula:

in which Ph is C₆H₅- or C₆H₄R, R is hydrogen or (C₁-C₃)-alkyl, R² is (C₁-C₃)-alkyl, R' is (C₈-C₁₈)-alkyl and X is halogen,

in a ratio to isothiazolone of 1:1 to 5:1, preferably 3.5:1.

The invention will now be explained in more detail with reference to the following examples, in which all parts and percentages are by weight unless otherwise stated.

In Examples 1 to 3, 1000 or 2000 ppm active ingredient of an aqueous solution of the isothiazolone biocide sold by Rohm and Haas Company as "Kathon 893" and containing as active ingredient 2-octyl-3-isothiazolone was emulsified with a mixture of non-ionic (300 or 600 ppm) and anionic (600 or 1200 ppm) surfactant with the additive to be tested. In Example 4, where surfactants were tested, emulsification was not necessary.

Each solution was tested for its isothiazolone content.

2.5% w/w sawdust was added to each solution and the solution was allowed to stand for 3 hours at 23ºC. The solution was then separated from the sawdust by filtration and assayed for its isothiazolone content. In the absence of an additive to prevent stripping, the loss of isothiazolone was typically 40 to 60%, with the exact value depending on the type of wood used, analytical error and tester error.

example 1

The following polyquaternary compounds were used as anti-stripping additives.

"Luviquat HM 552", a modified copolymer of vinylpyrrolidone and vinylimidazolinium methochloride;

"Gafquat 755N", a quaternary copolymer of vinylpyrrolidone and dimethylaminoethyl methacrylate;

"Polyquart H81", a polyamine-polyglycol condensation resin;

"Busan 77", a poly-oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride and

"RH-A", a polyquaternary dimethylamine ethyl methacrylate.

Table 1 shows the ratio of isothiazolone (IT) to additive for each case and the amount of isothiazolone to additive for each case and the amount of isothiazolone (in parts per million) before and after the test and the loss in percent. Table 1 Detectable isothiazolone (ppm) Additive Ratio IT:Additive before after % Loss Luviquat Hm 552 Gafquat 755N Polyquart H81 Busan 77

Example 2

The following simple quaternary salts were tested as in Example 1:

"RH-B", a solution of N-octyl-3-isothiazolone and dimethylbenzylammonium chloride (12.5%).

"Empigen BAC", alkyl dimethyl benzyl ammonium chloride and "Luviquat Mono CP", cetyl dimethyl (2) hydroxyethyl ammonium dihydrogen phosphate.

The results are shown in Table 2: Table 2 Detectable isothiazolone (ppm) Additive Ratio IT: Additive before after % Loss Empigen BAC Luviquat Mono CP

The effect of increasing the proportion of the additive can be clearly seen here.

Example 3

The following dispersants were tested as in Example 1:

"RH-C" (Rohm and Haas Company), a self-crosslinking polyacrylate;

"RH-D", a sodium salt of polyacrylic acid and

"RH-E", a low molecular weight polyacrylic acid.

The results are summarized in Table 3. Table 3 Detectable isothiazolone (ppm) Additive Ratio IT: Additive before after % Loss

Example 4

The following non-ionic surfactants were tested as in Example 1, but no additional surfactants were used for emulsification:

"SA1", nonylphenoxypolyethoxyethanol (EO content 8.5);

"SA2", octylphenoxypolyethoxyethanol (EO content 7 - 8);

"SA3", octylphenoxypolyethoxyethanol (EO content 15 - 16);

"SA4", octylphenoxypolyethoxyethanol (EO content 30).

Table 4 shows the results. Table 4 Detectable isothiazolone (ppm) Additive Ratio IT: Additive before after % Loss

Table 4 shows that the two non-ionic surfactants with an EO content outside the scope of the invention have no significant influence on the expulsion of isothiazolone, whereas the combination of SA1 and SA2 is very effective.

Claims (9)

1. Use in a solution containing isothiazolane of one or more of (a) a polyquaternary compound based on either polyamine or polyamine ether, polyvinylpyrrolidone, polyquaternary ammonium polymer or cationic copolymer based on acrylates, (b) a water-soluble and/or water-dispersible polymer containing either homopolymer(s) or copolymer(s) of (meth)acrylic acid(s) and/or ester(s), vinyl homopolymer(s) and/or copolymer(s) and/or polymer(s) based on glycol monomer(s) or ether monomer(s), (c) a nonionic surfactant having 3 to 12 alkylene oxide units, preferably ethylene oxide units, (d) a simple quaternary compound containing ammonium halide(s) of the formula in which Ph is C₆H₅- or C₆H₄R, R is hydrogen or (C₁-C₃)-alkyl, R² is (C₁-C₃)-alkyl, R' is (C₈-C₁₈)-alkyl and X is halogen, in a ratio to isothiazolone of 1:1 to 5:1, preferably 3.5:1, as an agent for controlling the expulsion of the isothiazolone from the solution when it is to be used as a wood treatment agent against sap staining upon repeated contact with wood. 2. Use according to claim 1 or 2, characterized in that when the nonionic surfactant is present, it contains either polyalkoxylate(s) of alkylphenol(s), alcohol(s), amine(s) or alkanolamide(s) or block copolymer(s) of ethylene oxides and propylene oxides. 3. Use according to claim 1 or 2, characterized in that the polyquaternary compound is a modified copolymer of vinylpyrrolidone and vinylimidazolium methochloride, a quaternary copolymer of vinylpyrrolidone and dimethylaminoethyl methacrylate, a polyamine-polyglycol condensation resin, a poly[oxyethylene(dimethylimino)ethylene(dimethylimino)ethylene dichloride] or a polyquaternary dimethylaminoethyl methacrylate. 4. Use according to one of the preceding claims, characterized in that the simple quaternary compound is dimethylbenzylammonium chloride (12.5%), an alkyldimethylbenzylammonium chloride or a cetyldimethyl-(2)-hydroxyethylammonium dihydrogen phosphate. 5. Use according to one of the preceding claims, characterized in that the dispersant is a self-crosslinking polyacrylate, a sodium salt of polyacrylic acid or a polyacrylic acid with a low molecular weight. 6. Use according to one of the preceding claims, characterized in that the nonionic surfactant is nonylphenoxypolyethoxyethanol (EO content 8.5) or octylphenoxypolyethoxyethanol (EO content 7-8). 7. Use according to one of the preceding claims, characterized in that the isothiazolone has the formula in which Y can be (C₁-C₁₈)alkyl or (C₃-C₁₂)cycloalkyl, each optionally substituted with one or more of hydroxy, halogen, cyano, alkylamino, dialkylamino, arylamino, carboxy, carbalkoxy, alkoxy, alkylthio, arylthio, haloalkoxy, cycloalkylamino, carbamoxy or isothiazolonyl; an unsubstituted or halogen-substituted (C₂-C₈)alkenyl or alkynyl; a (C₇-C₁₀)aralkyl, optionally substituted with one or more of halogen, (C₁-C₄)alkyl or (C₁-C₄)alkoxy; and an aryl optionally substituted with one or more of halogen, nitro, (C₁-C₄)alkyl, (C₁-C₄)alkylacylamino, carb(C₁-C₄)alkoxy or sulfamyl, and R¹ and R² are each independently hydrogen, halogen or (C₁-C₄)alkyl. 3. Use according to claim 7, characterized in that the isothiazolone contains one or more of 5,5-dichloro- 2-n-octyl-3-isothiazolone, 4,5-dichloro-2-cyclohexyl-3-isothiazolone and 2-n-octyl-3-isothiazolone. 9. A method for preventing the expulsion of isothiazolone from an isothiazolone-containing solution upon repeated contact with wood as a wood treatment agent against sap discoloration by incorporating into the solution one or more of (a) a polyquaternary compound based on either polyamine or polyamine ether, polyvinylpyrrolidone, polyquaternary ammonium polymer or cationic copolymer based on acrylates, (b) a water-soluble and/or water-dispersible polymer containing either homopolymer(s) or copolymer(s) of (meth)acrylic acid(s) and/or ester(s), vinyl homopolymer(s) and/or copolymer(s) and/or polymer(s) based on glycol monomer(s) or ether monomer(s) (c) a nonionic surfactant having 3 to 12 alkylene oxide units, preferably ethylene oxide units, (d) a simple quaternary compound containing ammonium halide(s) of the formula in which Ph is C₆H₅- or C₆H₄R, R is hydrogen or (C₁-C₃)alkyl, R² is (C₁-C₃)alkyl, R' is (C₈-C₁₈)alkyl and X is halogen, as defined in any one of claims 1-6, with a ratio to isothiazolone of 1:1 to 5:1, preferably 3.5:1.