JPH05124917A - Isothiazolone protecting method - Google Patents

Abstract

PURPOSE: To improve the stability of isothiazolone useful as a microbicide, especially the stability thereof in a concentrated solution of a metal working fluid(MWF) used for the purpose of lubrication, cooling, prevention, etc., of surface corrosion especially when working a metal. CONSTITUTION: (b) A sulfur-containing compound capable of reversibly producing an adduct of (a) a compound represented by the formula (Y is a 1-18C alkyl, a 3-12C cycloalkyl, a 2-8C alkenyl, etc.; R and R1 are each H, a 1-4C alkyl, a 4-8C cycloalkyl, etc.), e.g. 2n-octyl-3-isothiazolone (preferably a mercaptan, especially a nitrogen-based heterocyclic thiol, above all, the thiol having S bonded to the nitrogen-containing ring) or its salt in an effective amount is mixed in the compound (a) at least 0.1:1, especially at least 0.5:1 molar ratio of the components (b):(a) to protect the compound (a) against the chemical hydrolysis. the produced adduct can be hydrolyzed by dilution to dissociate the compound (a).

Description

Detailed Description of the Invention

The present invention relates to the stabilization of 3-isothiazolone compounds. In particular, it relates to the stabilization of 3-isothiazolone compounds by incorporating certain sulfur-based compounds in metal working fluid concentrates.

BACKGROUND OF THE INVENTION Isothiazolone has been of great industrial interest as a microbicide to prevent damage to certain aqueous and non-aqueous products due to microorganisms. Isothiazolone is a highly effective microbicide (the term "microbicide" as used herein includes bactericides, fungicides and algaecides, and microbicidal activity refers to microorganisms such as It is intended to include both the removal of bacteria, fungi, and algae, and the inhibition or prevention of their growth). By proper selection of isothiazolone functional groups, isothiazolones are effective in a wide range of applications.

One of the significant areas of application of isothiazolones
One is the use as a microbicide in metal working fluids. Metal working fluids include, among others, alkanolamines, petroleum-based sulfonated surfactants, oils (naphthene-based, paraffin-based, etc.), chlorinated paraffins and fatty esters, sulfated fatty compounds, phosphate esters, fatty acids and their amines. Proprietary combination of chemicals containing ingredients such as salts, glycols, polyglycols, borate esters and amides
Is. Metal working fluids are used in milling, machining, drilling, and other processing to process metals for purposes such as lubrication, cooling, and surface corrosion prevention. The metal working fluid is an active metal working fluid [metal wor
king fluid (MWF)] Sold in the form of a concentrated liquid, diluted to 1-10% active ingredient with water when used.

Microorganisms grow because the metal working fluid is recycled and stored. Isothiazolones have been found to be effective in preventing the growth of such microorganisms. However, certain components of metal working fluids tend to destroy isothiazolones and eliminate the antimicrobial activity of isothiazolones. This is a particular problem when the MWF is in the form of a concentrate. It was found that even some other microbicides used in combination with isothiazolones can attack isothiazolones.
An example of this is the sodium salt of pyridine-N-oxide [sodium omadine]. It was found to remove 5-chloro-2-methylisothiazolone from any system used with 5-chloro-2-methylisothiazolone.

Practically and generally, the efficacy of isothiazolones in many environments, whether prior to or after addition to the substrate to be treated, is not stable under the practical conditions of long term storage. , It has long been recognized that it will decrease. Therefore, methods for improving the stability of isothiazolones have long been sought.

US Pat. Nos. 3,870,795 and 4,067,878 teach the addition of metal nitrite or metal nitrate to stabilize isothiazolones against chemical degradation. However, other common metal salts, including carbonates, sulphates, chlorates, perchlorates, and chlorides, are normally isothiazolones in aqueous or hydroxyl solvent solutions. Has been taught to be ineffective in stabilizing.
U.S. Pat. Nos. 4,150,026 and 4,24
No. 1,214 teaches that metal complex salts of isothiazolones are useful because they enhance the thermal stability while retaining biological activity.

In general, certain stabilizers for isothiazolones are used in the conditions of use in which the metal salt causes problems such as corrosion, latex coagulation, insolubility in non-aqueous media, interaction with the substrate to be treated, etc. Known to be used.
Formaldehyde or formaldehyde dissociative chemical agents are known as stabilizers (US Pat. No. 4,16).
5,318 and 4,129,448), as well as certain organic chemical agents such as orthoesters (European Patent 315,464), epoxides (European Patent 342,852), and carbonyl compounds. (European Patent Application No. 9031241
7.0) is also known as a stabilizer.

The inventor has found a class of compounds that provide considerable and surprising stability to isothiazolones against degradation, especially in MWF concentrate. Therefore, in its broadest aspect, the present invention

[Chemical 2]

Wherein Y is each optionally hydroxy, halo, cyano, alkylamino, dialkylamine, arylamino, carboxy, carboalkoxy,
(C ₁ -C ₁₈ ) alkyl or (C ₃ -C ₁₂ ) cyclo, optionally substituted with one or more of alkoxy, aryloxy, alkylthio, arylthio, haloalkoxy, cycloalkylamino, carbamoxy, or isothiazolonyl. alkyl; unsubstituted or halo-substituted (C ₂ -C ₈₎ alkenyl or alkynyl; optionally, halogen, (C ₁ -C ₄₎ alkyl or (C ₁ -
C ₄₎ may be substituted with one or more alkoxy, (C ₇ -C ₁₀₎ aralkyl; and optionally, halogen, nitro, (C ₁ -C ₄₎ alkyl, (C
_1- C ₄ ) alkyl acylamino, carbo (C ₁ -C
₄ ) aryl optionally substituted with alkoxy or sulfamyl; and R ₁ and R ₂ are each independently hydrogen, halogen, (C ₁ -C ₄ ) alkyl, (C ₄ -C ₈ ). Cycloalkyl, or joined together to form phenyl,

A method of protecting isothiazolones having a chemical decomposition property against chemical decomposition, wherein an effective amount of a sulfur-containing compound or a salt thereof capable of reversibly forming an adduct with said isothiazolone is A method of protection is provided comprising admixing with isothiazolone.

The sulphur-containing compounds of the present invention form isothiazolones and hydrolysable adducts, which are hydrolyzed to reverse adduct formation in such cases, usually by dilution. it is conceivable that. However, the present invention is not limited to such a case.

The invention provides, in particular, an advantageous form of protection or stabilization. These stabilizers can be used to lock up isothiazolones in the form of stable adducts that resist chemical degradation.
Then, when desired, these stabilizers can dissociate the isothiazolone by reversing the formation of the adduct, usually by simply diluting the product. Accordingly, another aspect of the invention comprises an adduct of an isothiazolone as defined above with a sulfur-containing compound or salt thereof, said adduct being a compound capable of decomposing to dissociate said isothiazolone. Is to provide. Preferably, these adducts hydrolyze to dissociate the isothiazolone.

In another aspect, the present invention provides a composition comprising an isothiazolone as defined above, a sulfur containing compound as defined above, and optionally a solvent. In yet another aspect, the invention consists in using a sulfur-containing compound as defined above to protect the isothiazolone against chemical degradation.

The stabilization found in the present invention is
This is especially surprising in view of the previously known immiscibility of chloro-2-methylisothiazolone and the aforementioned sodium salt of 2-mercaptopyridine-N-oxide [sodium omadine]. .. In view of what has been found by the present invention, it is presently believed that the disappearance of isothiazolone in this case, as in the present invention, sodium omazine forms isothiazolones and adducts. However, the adducts in this case are irreversibly formed and cannot recapture the isothiazolone. The scope of the invention extends only to adducts where the production is reversible.

The present invention is of particular value in the field of metal working fluids, which are usually stored in the form of concentrates.
Certain components of MWF are extremely aggressive to isothiazolones when in concentrated form. However, when it is diluted with a normal use diluent, the threat almost disappears. Therefore, the present invention can be used to protect the isothiazolone in a concentrate by adding the stabilizer of the present invention. Then, by diluting, the isothiazolone is automatically dissociated by hydrolysis of the isothiazolone / stabilizer adduct.

Stabilized isothiazolones are described in US Pat. Nos. 3,523,121 and 3,761,488.
Including the isothiazolones described in US Pat.

[Chemical 3]

Is represented by

Preferred Y substituents are substituted or unsubstituted
(C₁-C₁₈) Alkyl or (C ₃-C₁₂) Cycloa
Preferably Rukiru and R is H or Me.
And then R¹Is preferably H. like that
Representative examples of preferred Y substituents are methyl, ethyl, propyl
Ru, isopropyl, butyl, hexyl, octyl, sikh
Rohexyl, benzyl, 3,4-dichlorobenzyl, 4
-Methoxybenzyl, 4-chlorobenzyl, 3,4-di
Chlorophenyl, 4-methoxyphenyl, hydroxy
Cyl, chloromethyl, chloropropyl, hydrogen and the like.

Particularly preferred isothiazolones are 2-methyl-3-isothiazolone and 2-n-octyl-3-.
Isothiazolone.

Preferred stabilizers include nitrogen-containing aromatic rings,
Particularly included are compounds having a sulfur atom attached to a nitrogen-based heterocyclic thiol. Especially preferred is 4
-Mercaptopyridine, sodium salt of 2-mercaptopyridine, 2-mercaptobenzothiazole, and 4
-Methyl-4-H-1,2,4-thiazole-3-thiol. Other preferred compounds include 2-methylthiobenzothiazole, 2-thiohydantoin, methylenebisthiocyanate, L-cystine, and 4-R (thiazolidine-thione) -4-carbonic acid.

In order to effectively protect the isothiazolone, the stabilizer: isothiazolone molar ratio is preferably
It is at least 0.1: 1, more preferably at least 0.5: 1. Generally, the minimum molar ratio depends on the aggressiveness of the system containing the isothiazolone. A typically preferred range is 0.5: 1 to 1.5: 1.
Is. However, some of the compounds that act as stabilizers may find other uses in systems where isothiazolones have been added. For example, they are used as microbicides by themselves. In such cases, the stabilizer: isothiazolone molar ratio is 10: 1.
It may be more than.

The composition of isothiazolone and stabilizer is
A solvent may be additionally included. A suitable solvent is any organic solvent that dissolves isothiazolone, is miscible in the planned end use, does not destabilize isothiazolone, and does not react with the stabilizer so as to inhibit the protective action of the stabilizer. Is.

Hydroxyl solvents such as polyols such as glycols, alcohols can be used. Hydrocarbons, either aliphatic or aromatic, are also useful solvents in certain formulations.

Preferred solvents are capped polyols in which the free hydroxyl groups have been replaced with other ether or ester functional groups. Especially preferred are 2,5,8,11-tetraoxadodecane (usually known as triethylene glycol dimethyl ether), and 4,7-dioxaundecanol-1 acetate (usually as diethylene glycol butyl ether acetate). It is known).

Water is a solvent for some preferred isothiazolones and stabilizers can be used in aqueous formulations.

In some cases, the adduct produced by the present invention may be in the form of a solid precipitate. Generally, this can be avoided by standard techniques for increasing the soluble product of the system, such as addition of emulsifiers or dilution of the system. One of ordinary skill in the art would have little difficulty in modifying the conditions to avoid the formation of a precipitate if the formation of the precipitate were problematic in a particular case.

It is known in the art that the performance of microbicides is enhanced by combining them with one or more other microbicides. Therefore, other known microbicides can be advantageously combined with the compositions or compounds of the present invention.

These protected isothiazolones can be used anywhere that they are contaminated by bacteria, fungi, yeasts or algae. Typical locations are aqueous systems, such as cooling water, wash water, oil systems such as cutting oil, the oil industry, etc., where it is necessary to kill the microorganisms and to suppress the growth of the microorganisms. However, it can also be used in all applications where the known microbicidal compositions are said to be useful. The preferred use of these compositions is wood,
Paint, adhesive, glue, paper, knitted fabric, leather, plastic, cardboard, lubricant, cosmetics, caulk,
Protect feed and industrial cooling water from biocide.

The invention is illustrated in the following examples. All percentages are weight percentages unless otherwise stated. In the following examples, a method for the determination of isothiazolone in metal working fluids is described by Rohm and Haas Com.
pany) 's “Kathon ^TM 886 MWMicrobicide and Kathon ^TM
893 MW Fungicide: Analysis in Metalworking Fluids b
y High-Performance Liquid Chromatography ”.

Example 1 This example illustrates the protection provided to isothiazolones by the stabilizers of this invention. Monoethanolamine is known to degrade isothiazolones when contacted with isothiazolones in concentrated form. This material is a component of the metal working fluid and therefore M
There is a particular problem when present with isothiazolone in the WF concentrate. In the following example, 1: 1 water / propylene glycol solvent, 10% monoethanolamine, 900 ppm of 2n-octyl-3-isothiazolone.
, And a test system consisting of the stabilizer according to the invention. Maintain the system at 25 ° C and
The concentration of residual isothiazolone was measured after 2, 4, 8 and 12 weeks, respectively. The concentration of isothiazolone was taken at a suitable time by taking a portion of it from the system and adding it to 50% with a 1: 1 water / propylene glycol solution.
Diluted in fold and then analyzed for isothiazolone by HPLC. The results are shown in Table 1. In this Table 1, it should be understood that the initial concentration of isothiazolone is 900 ppm in each case. The following description is the measured value expressed in%, and the error range is ± 5%
Is.

[Table 1]

Referring to Table 1, the stabilizer-free isothiazolone is rapidly degraded by monoethanolamine and completely disappears within 2 weeks. Two
In the case of two comparative examples, these are examples where the formation of the isothiazolone-stabilizer adduct is irreversible. Therefore, taking a portion of the sample for analysis and diluting it 50-fold does not dissociate the isothiazolone by hydrolysis. Instead, it remains part of the adjunct, and therefore
There is no detectable activity and no microbicidal activity.

The present invention is limited to sulfur compounds which form reversible adducts with isothiazolones. As can be seen in the remaining examples in Table 1, these offer very good protection for isothiazolones. As a rule of thumb, when compared to the loss of isothiazolone in the absence of stabilizer, effective stabilization is considered to be achieved if 60% of isothiazolone is retained after 4 weeks. It is believed that effective stabilization is achieved if 80% remains.

Example 2 Tests were conducted with samples of two "synthetic" metalworking fluid concentrates, two "semi-synthetic" MWF concentrates, and one "emulsion" MWF concentrate. It was In all five cases, the stability of 2n-octyl-3-isothiazolone was compared in the absence of stabilizer and in the presence of sodium omazine (2-mercaptopyridine-N-oxide). MWF concentrates A and B contain synthetic esters, solubilizers, coupling agents, in addition to oil and amine water.
It was a "synthetic" type containing a corrosion inhibitor and an extreme pressure agent. MWF concentrates C and D are similar in composition to synthetic oils but do not contain synthetic esters, but additionally contain lubricating oils and emulsifiers. It was a "semi-synthetic" type. In each case, the analysis of isothiazolone content was performed as in Example 1. The error range was ± 5%. In all cases, the amount of isothiazolone present was 1,000 ppm. The amount of sodium omadine present is as set forth in Table 2. The results obtained are shown in Table 2.

[Table 2]

This Table 2 clearly shows the dramatic effect of isothiazolones in the presence of stabilizers.
In the case of MWF concentrate E, when the components of the system are less aggressive towards isothiazolones,
It has been shown that stabilizers successfully provide excellent protection even in very small amounts.

Claims (12)

[Claims] 1. The formula: Wherein Y is each hydroxy, halo,
Cyano, alkylamino, dialkylamine, arylamino, carboxy, carboalkoxy, alkoxy,
(C ₁ -C ₁₈ ) alkyl or (C ₃ -C ₁ ), optionally substituted by one or more of aryloxy, alkylthio, arylthio, haloalkoxy, cycloalkylamino, carbamoxy, or isothiazolonyl.
₁₂₎ cycloalkyl; unsubstituted or halo-substituted (C ₂ -
C ₈ ) alkenyl or alkynyl; optionally substituted with one or more of halogen, (C ₁ -C ₄ ) alkyl or (C ₁ -C ₄ ) alkoxy,
(C ₇ -C ₁₀ ) aralkyl; and optionally halogen, nitro, (C ₁ -C ₄ ) alkyl, (C ₁ -C ₄ ).
Alkyl - acylamino, carboxy (C ₁ -C ₄₎ alkoxy or sulfamyl optionally substituted, aryl; and R ₁ and R ₂ are, each independently, hydrogen, halogen, (C ₁ -C ₄ ) Alkyl, (C ₄
-C ₈₎ cycloalkyl, or in combination together to form a phenyl, isothiazolones with a method of protecting against chemical degradation, reversible said isothiazolone and adduct Said protection method comprising admixing into said isothiazolone an effective amount of a sulfur-containing compound or a salt thereof which can be produced in situ. 2. The protection method according to claim 1, wherein the protection of isothiazolone is terminated by the decomposition of the adduct to dissociate the isothiazolone, preferably by hydrolysis of the adduct. 3. Protection of isothiazolone in a metal working fluid concentrate and hydrolysis of the adduct by diluting this concentrate to dissociate the isothiazolone.
The protection method according to claim 2. 4. Y is (C ₁ -C ₁₈ ) alkyl or (C ₃ -C ₁₂ ) cycloalkyl; R is H or Me; R ¹ is H. The protection method according to any one of 1. 5. The protective method according to claim 4, wherein the isothiazolone is 2-methyl-3-isothiazolone or 2n-octyl-3-isothiazolone. 6. R and R ¹ are each independently hydrogen, (C ₁ -C ₄ ) alkyl, (C ₄ -C ₈ ) cycloalkyl, or are joined together to form phenyl. And a sulfur-containing compound is a mercaptan or a salt thereof, preferably a nitrogen-based heterocyclic thiol or a salt thereof. 7. The sulfur-containing compound according to claim 1, wherein the sulfur-containing compound has a sulfur atom bonded to a nitrogen-containing ring and is a nitrogen-based heterocyclic thiol or a salt thereof. How to protect. 8. The sulfur-containing compound is mercaptobenzothiazole, sodium salt of 2-mercaptopyridine-N-oxide, 2-mercaptopyridine, 4-mercaptopyridine, benzothiazole, 2-thiohydantoin, L-cystine, methylenebis-. Thiocyanate, 2
-Methylthiobenzothiazole, 4-methyl-4-H-
The protection method according to any one of claims 1 to 5, which is 1,2,4-thiazole-3-thiol, 4-R- (thiazolidinethione) -4-carbonic acid, or 2-mercaptopyrimidine. 9. A composition comprising an isothiazolone as claimed in claims 1-8, a sulfur containing compound as claimed in claims 1-8 or a salt thereof, and optionally a solvent. 10. A protective method or composition according to claim 1, wherein the molar ratio of sulfur-containing compound: isothiazolone is at least 0.1: 1, preferably at least 0.5: 1. object. 11. A sulfur-containing compound or a salt thereof as described in claim 1 or any one of claims 6 to 8 and capable of reversibly producing an isothiazolone and an adduct, isothiazolone. Method used to protect against chemical degradation of. 12. A compound comprising an isothiazolone as defined in any one of claims 1 to 11 and a sulfur-containing compound as defined in any one of claims 1 to 11 or an adduct of a salt thereof. Wherein the adduct preferably decomposes by hydrolysis to dissociate the isothiazolone.