EP0773281B1 - Preparations for production of stabilized coolantiubricants - Google Patents

Description

The present invention relates to additive mixtures for cooling lubricant products and cooling lubricant products containing a Isothiazolone and one against chemical decomposition of isothiazolone effective stabilizer included.

Isothiazolone compounds are effective as bactericidal and / or fungicidal active ingredients in cooling lubricants for metal processing known. However, certain components tend to be in Metalworking fluids for the destruction of isothiazolones and thus eliminate their microbiological protective activity. This is especially the case when the metal processing fluids in concentrated form.

Also other microbicides used in combination with isothiazolones Isothiazolones can attack. An example for this is the sodium salt of 2-mercapto-pyridine-N-oxide (sodium omadine), that 5-chloro-2-methylisothiazolone decomposes in each system, in which both exist together.

It was therefore looking for ways to improve the stability of To improve isothiazolone solutions.

From US-A-3 870 795 and US-A-4 067 878 it is known that Isothiazolones by addition of a metal nitrite or a Metal nitrates are stabilized against chemical decomposition can. Furthermore, it is disclosed that other common salts, including carbonates, sulfates, chlorates, perchlorates and Chlorides to stabilize isothiazolone solutions not are effective.

EP-A-0 425 143, US-A-4 150 026 and US-A-4 241 214 disclose that metal salt complexes of isothiazolones due to their improved thermal stability are used while the biological activity is maintained.

Furthermore, the use of certain organic stabilizers for isothiazolones, for example from EP-A-0 375,367 and EP-A-0 530 986. These are generally Used where metal salts cause problems such as corrosion, coagulation of latices, insolubility in non-aqueous media, interaction with the substrate to be stabilized and the like cause.

For example, in US-A-4,165,318 and US-A-4,129,448 Formaldehyde or formaldehyde-releasing chemicals as Stabilizers disclosed. From EP-A-0 315 464 are orthoesters and EP-A-0 342 852 discloses epoxides as stabilizing agents known.

Also from EP-B-0 443 821 are additive mixtures for cooling lubricant products known, according to the preamble of claim 1 isothiazolone and one against chemical decomposition of the isothiazolone effective stabilizer. For stabilization Isothiazolone there is the use of sulfur Compounds or salts thereof disclosed with the EP 96 25 0190.4

Isothiazolone can reversibly form an adduct, in particular Compounds in which a sulfur atom is added to a nitrogen, is bound aromatic ring. As suitable compounds (in EP-B-0 443 821) 4-mercaptopyridine, the Sodium salt of 2-mercaptopyridine, 2-mercaptobenzothiazole and 4-methyl-4-H-1,2,4-triazole-3-thiol called. Other compounds mentioned are 2-methylthiobenzothiazole, 2-thiohydantoin, methylenebisthiocyanate, L-cystine and 4-R (thiazoliden-thione-4-carboxylic acid) , The stabilizer effective ratio of stabilizer to isothiazolone is at least 0.1: 1 according to EP-B-0 443 821, in particular between 0.5: 1 to 1.5: 1.

The compositions known from EP-B-0 443 821 Isothiazolone and stabilizer can additionally solvents contain. Preferred solvents are so-called "capped polyols", such as. Triethylene.

From EP-A-0 450 916 a method for the stabilization of 3-Isothiazolone known in which an effective amount of phenoxyalkanol is included, preferably the 3-isothiazolone in which phenoxyalkanol is dissolved.

In an attempt to prepare preparations according to the state of To formulate technique, one receives however mostly inhomogeneous or unstable solutions, especially after short storage times. These Inhomogeneities complicate precise dosage of the isothiazolone / stabilizer compositions or make it impossible. A separate addition of active ingredient and stabilizer is indeed possible, but not desirable in practice and prone to error.

Accordingly, the present invention is based on the object Additive mixtures for cooling lubricant products available which isothiazolones as bactericidal and / or fungicidal Active ingredients contain, the cooling lubricant concentrates or from it manufactured cooling lubricant from microbial attack protect and the durability and life of the cooling lubricant products improve. The additive mixtures according to the invention should themselves be sufficiently stable and under practical conditions storable and durable.

It is also an object of the present invention to provide isothiazolone and formulating stabilizer-containing compositions so that they are easy to commercial coolants, for example be metered by adding a liquid preparation can. The metered addition should be in a cooling lubricant concentrate or in a cooling lubricant, preferably a water-mixed Coolant, can be done.

It is also an object of the present invention to provide effective cooling lubricant products to be available, facing each other the state of the art in that they have a have increased stability and improved efficacy.

The tasks are characterized by the characterizing features of Claims 1 and 11 solved. According to claim 1 is in the additive mixtures additionally provided a solubilizer, that of phenoxyethanol, phenoxypropanols, 1-methoxy-2-propanol, and mixtures thereof are selected. The solver is for example in an amount of 30 to 91.7 wt .-%, for example 30 to 75, preferably 40 to 70 Wt .-%, more preferably 50 to 65 wt .-% and in particular about 58 wt .-% in the additive mixture.

The cooling lubricant products contain in addition to the usual Ingredients an additive mixture according to the invention. The cooling lubricant products can be used as cooling lubricant concentrate or contain the cooling lubricant concentrate. Accordingly, can the additives of the invention in cooling lubricant concentrates are introduced, which then to coolants be diluted. The cooling lubricant products can be used as Solution or as an emulsion. Preferably, water-mixed Coolant produced.

wiedergegeben, in der
Y eine (C₁-C₁₈)-Alkyl- oder (C₃-C₁₂)-Cycloalkylgruppe ist, die mit einer oder mehreren Hydroxy-, Cyano-, Alkylamino-, Dialkylamino-, Aryl-, Amino-, Carboxy-, Carbalkoxy-, Alkoxy-, Aryloxy-, Alkylthio-, Arylthio-, Cycloalkylamino-, Carbamoxy- oder Isothiazolonylgruppen substituiert sein kann, eine unsubstituierte (C₂-C₈)-Alkenyl- oder -Alkinylgruppe, eine (C₇-C₁₀)-Aralkylgruppe, die mit einer oder mehreren (C₁-C₄)-Alkyl- oder (C₁-C₄)-Alkoxygruppen substituiert sein kann, oder eine Arylgruppe ist, die mit einer oder mehreren Nitro-, (C₁-C₄)-Alkyl-, (C₁-C₄)-Alkyl-acrylamino-, Carb-(C₁-C₄)-alkoxy- oder Sulfamylgruppen substituiert sein kann, und
R und R¹ jeweils unabhängig Wasserstoff, eine (C₁-C₄)-Alkylgruppe, eine (C₄-C₈)-Cycloalkylgruppe sind oder miteinander unter Ausbildung einer Benzoisothiazolonylgruppe verbunden sind, wobei N-Oktyl-Isothiazolon bevorzugt ist.The isothiazolones used in the additive mixture according to the invention are halogen-free and are represented by the formula

reproduced in the
Y is a (C ₁ -C ₁₈ ) alkyl or (C ₃ -C ₁₂ ) cycloalkyl group containing one or more hydroxy, cyano, alkylamino, dialkylamino, aryl, amino, carboxy, Carbalkoxy, alkoxy, aryloxy, alkylthio, arylthio, cycloalkylamino, carbamoxy or isothiazolonyl groups, an unsubstituted (C ₂ -C ₈ ) alkenyl or alkynyl group, a (C ₇ -C ₁₀ ) -Aralkylgruppe which may be substituted with one or more (C ₁ -C ₄ ) alkyl or (C ₁ -C ₄ ) alkoxy groups, or an aryl group which is reacted with one or more nitro, (C ₁ -C ₄ ) alkyl, (C ₁ -C ₄ ) alkyl-acrylamino, carb (C ₁ -C ₄ ) alkoxy or sulfamyl groups, and
R and R ^{1 are} each independently hydrogen, a (C ₁ -C ₄ ) alkyl group, a (C ₄ -C ₈ ) cycloalkyl group or linked together to form a benzoisothiazolonyl group, with N-octyl isothiazolone being preferred.

As stabilizers or stabilizer mixtures for the isothiazolone compounds are known from the prior art Compounds, and in particular sulfur-containing compounds or Salts thereof which are reversible with the isothiazolone Can form adduct. In particular, heterocyclic are Sulfur-nitrogen compounds such as 2-mercaptopyridine N-oxide and corresponding salts, preferably alkali metal or ammonium salts such as. Pyrion-Na (40% aqueous solution of 2-mercaptopyridine N-oxide sodium salt), 2-mercaptopyridine N-oxide metal salt complexes such as zinc pyrithione (e.g., as a 48% aqueous dispersion), 2,2'-dithiobis (pyridine N-oxide) (pyrion disulfide), as well as Mixtures thereof. In particular, pyrion-Na, zinc pyrithione and pyrion disulfide preferred. In addition, according to the invention also mild oxidants such as iodopropynyl butyl carbamate, hydrogen peroxide, t-butyl hydroperoxide, sodium bromate and Cu (II) salts as co-stabilizers, with sodium bromate, hydrogen peroxide, 2-tert-butyl-6-methylphenol and pyrion disulfide are preferred as co-stabilizers.

a. 5 bis 45 Gew.-%, beispielseise 15 bis 45 Gew.-%, vorzugsweise 20 bis 30 Gew.-% und insbesondere etwa 24,5 Gew.-% einer 45%igen n-Octylisothiazolon-Lösung in 1,2-Propylenglykol (Kathon 893),

b. 3,3 bis 25 Gew.-%, beispielsweise 10 bis 25 Gew.-%, vorzugsweise 15 bis 20 Gew.-% und insbesondere etwa 17,5 Gew.-% einer 40%igen wäßrigen 2-Mercaptopyridin-N-oxid-Natriumsalz-Lösung (Pyrion-Na) und

c. 30 bis 91,7 Gew.-%, beispielsweise 30 bis 75 Gew.-%, vorzugsweise 50 bis 65 Gew.-% und insbesondere etwa 58 Gew.-% Phenoxyethanol, Phenoxypropanol oder 1-Methoxypropanol-2.

Particularly suitable are preparations comprising the following components:

a. 5 to 45 wt .-%, for example 15 to 45 wt .-%, preferably 20 to 30 wt .-% and in particular about 24.5 wt .-% of a 45% n-Octylisothiazolon solution in 1,2-propylene glycol (Kathon 893),

b. 3.3 to 25 wt .-%, for example 10 to 25 wt .-%, preferably 15 to 20 wt .-% and in particular about 17.5 wt .-% of a 40% aqueous 2-mercaptopyridine N-oxide Sodium salt solution (Pyrion-Na) and

c. 30 to 91.7 wt .-%, for example 30 to 75 wt .-%, preferably 50 to 65 wt .-% and in particular about 58 wt .-% phenoxyethanol, phenoxypropanol or 1-methoxy-2-propanol.

Accordingly, the isothiazolone content in the additive mixture 2.25 to 20.25% by weight, for example 6.75 to 20.25% by weight, preferably 9 to 13.5% by weight and in particular about 11% by weight be.

The stabilizer content in the additive mixture may be about 1.3 to 10 wt .-%, for example 4 to 10 wt .-%, preferably 6 to 8 Wt .-% and in particular about 7 wt .-% amount, for example also 0.05 to 1.0, preferably 0.5 to 0.1 wt.%, in particular 0.2 wt .-% co-catalyst may be present.

The molar ratio isothiazolone compound: stabilizer is for example at least 10: 1, preferably between 1.5: 1 and 1: 1.5 and especially about 1: 1, such as between 1.1: 1 and 1: 1.27.

The additive mixtures are preferably in commercial Incorporated cooling lubricant concentrates, from which then Dilutions may be made with water, e.g. 4% dilutions.

The liquid preparations may optionally contain further additives contain the functional properties of the cooling lubricant or cooling lubricant additive.

According to the invention, the active ingredient (isothiazolone) and the Stabilizer (for example, Pyrion-Na) as a liquid, stable Preparation in a one-component system. The preparation is well dosed and can be stored under practical conditions and durable. Also advantageous is the good handling of the preparation, compared to storage, preparation and dosing of active substances present in two-component systems and stabilizers.

The additive mixtures according to the invention can be coolants concentrates be added effectively, so that their durability and the lifetime of the finished cooling lubricant products, is improved compared to known systems. The raised Stability of the preparations according to the invention is evident especially in the lower tendency to form sediments.

Surprisingly, it was found that the inventive Combination of isothiazolone, stabilizer and special Solubilizers not only the handling and dosage of Means facilitated, it additionally improves the stability and in particular the effectiveness of the biocide mixture.

The achieved synergistic effect when using a inventive additive mixture in cooling lubricant products is illustrated by the following examples.

Examples

In the following examples, Kathon RH 893 designates a 45% n-Octylisothiazolone solution in 1,2-propylene glycol and pyrione-Na a 40% aqueous 2-mercaptopyridine N-oxide sodium salt solution.

example 1 : Stabilization of N-octylisothiazolone in cooling lubricants

In a series of experiments, the stability of Kathon RH 893 was monitored in a cooling lubricant (Shell Dromus B) with and without stabilizer additive via an active ingredient determination. For this purpose, 0.28% Kathon 893 (corresponding to 0.1275% N-octylisothiazolone, NOITZ) as well as stabilizers in different molar ratios in 60 g of Shell Dromus B were incorporated. From these concentrates, 5% emulsions with demineralized (DI) water were used in each case shortly before the HPLC determination of the isothiazolone content. The concentrates were stored at room temperature or 40 ° C in clear glass. stabilizer Mol-Ratio. Noitz: rod. Appearance of the concentrate NOITZ content of the emulsion Zero: n. 6d at RT (40 ° C) n. 20d at RT (40 ° C) without clear, reddish brown 0.13% 0.13% (0.09%) 0.11% (0.03%) 0.0233% Na-pyrione (40%) 10: 1 clear, very dark 0.13% 0.13% (0.12%) 0.12% (0.07%) 0.2233% Na-pyrione (40%) 1: 1 clear, very dark 0.14% 0.13% (0.13%) 0.13% (0.13%) 0.015% pyrion disulfide (96%) 10: 1 clear, reddish brown 0.13% 0.12% (0.12%) 0.12% (0.09%) 0.1572% pyrion disulfide (96%) 1: 1 cloudy, reddish brown 0.13% 0.13% (0.12% ) 0.12% (0.12%)

This experiment shows that by adding the stabilizers a considerable stabilization of NOITZ in cooling lubricant concentrates is reached. But this experiment also shows that the Addition of Na-Pyrion or Pyriondisulfid to deep discoloration of solutions and turbidities or sediments.

Example 2: N-octylisothiazolone stabilization - Compatibility of Kathon 893 with Pyrion-Na

The compatibility and stability of preparations based from 2 parts Kathon 893 and 0.5 to 4.0 parts Pyrion-Na (40%), in 0.5% concentration levels, without the addition of further solubilizers was tested after storage in clear glass at room temperature. The initially clear, yellow solutions (zero value or after 18 days) were partly biphasic after 3 months low precipitation.

Preparations based on Kathon 893 and Pyrion-Na in molar ratio 1: 1 to 1: 5 (without the addition of further solubilizers) were inhomogeneous after 5 months storage at room temperature. The stability tended to increase with increasing pyrion-Na content rather off.

Example 3: N-octylisothiazolone stabilization - Compatibility of Kathon 893 with pyrione-Na (MV 1: 1.27) in the presence of solubilizers

The compatibility and stability of preparations based of 40 parts of Kathon 893 and 40 parts of Pyrion-Na (40%) in various solubilizers were in clear glass at room temperature tested (molar ratio of N-octylisothiazolone: 2-mercaptopyridine-N-oxide-Na = 1: 1.27). The initially clear, homogeneous yellow bis orange-yellow solutions (zero values) tended to be time-dependent Formation of (yellow) precipitation. With hexylene glycol, dipropylene glycol, 1,2-propylene glycol and phenoxyethanol followed Sediment for 6 months, slightly less with butyl diglycol and 1-methoxy-2-propanol and virtually none with phenoxypropanol. The Solutions had no unpleasant sulfur odor and were practically unchanged yellow-orange colored.

Example 4: N-octylisothiazolone stabilization - Compatibility of Kathon 893 with pyrion-Na (MV 1: 0.9) in the presence of solubilizers

The compatibility and stability of preparations based of 35 parts Kathon 893 and 25 parts Pyrion-Na (40%) in various Solubilizers were tested in clear glass at room temperature (Molar ratio of N-octylisothiazolone: 2-mercaptopyridine-N-oxide-Na = 1: 0.9). The initially clear, homogeneous yellow bis Yellow-red solutions (zero values) tended to form over time of (yellow) precipitates and discolored depending on the solvent different strengths. The tendency to form Sediments were lower than in the test series with a N-octylisothiazolone / 2-mercaptopyridine-Na-oxide-Na ratio of 1: 1.27. Particularly intense dark colored was the preparation with butyldiglycol, slightly less dark colored patterns were with Hexylene glycol or dipropylene glycol, only slightly orange-yellow dyed were samples with 1-methoxy-2-propanol and 1,2-propylene glycol, during preparations with phenoxyethanol or phenoxypropanol were virtually unchanged yellow colored. With hexylene glycol and phenoxypropanol occur after 6 months at room temperature only low precipitation, solutions with phenoxyethanol were practically precipitation free. The solutions showed no unpleasant Sulfur smell on.

Example 5: N-octylisothiazolone stabilization - Stability of preparations

Formulations based on Kathon 893 and Pyrion-Na (40%) were in the molar ratio 1: 1 to 1: 5 in different Solver and solved for compatibility and stability examined. Total drug content (sum of N-octylisothiazolone and 2-mercaptopyridine N-oxide-Na salt) was about 18%.

After 6 months of storage at room temperature in clear glass were received the following results:

With increasing Kathon 893 content, the first discolored clear, yellow solutions slightly darker or deep dark red. Little changed in color were preparations with the solubilizers 1,2-propylene glycol, phenoxypropanol and phenoxyethanol in all tested molar ratios. Somewhat darker were Solutions with 1-methoxy-2-propanol and dipropylene glycol and deep dark red were solutions with hexylene glycol and in particular Diglycol.

The formation of rainfall and inhomogeneities was not primarily from the molar ratio of the active ingredients but rather from the solubilizer dependent. Comparatively little precipitation occurred Solutions with a phenoxyethanol, phenoxypropanol or 1-methoxypropanol-2 content on.

By contrast, voluminous sediments formed in Solutions with butyldiglycol content. With the other solicitors There were also some precipitations.

The investigations show that the stability and tolerability of Kathon 893 with Pyrion-Na partly strongly of the kind of Solubilizer and the molar ratio of the active ingredients dependent is.

Example 6: Stabilization of N-octylisothiazolone in cooling lubricants

In a series of experiments, the stability of Kathon 893 in Coolant concentrates without and with stabilizer additive followed by drug degradation after storage. In this test series the concentrates were stored at 40 ° C in clear glass.

A Kombination aus 24,5 Gew.-% Kathon 893, 17,5 Gew.-% Pyrion-Na und 58 Gew.-% 1-Methoxypropanol-2

B Kombination aus 24,5 Gew.-% Kathon 893, 17,5 Gew.-% Pyrion-Na und 58 Gew.-% Phenoxyethanol

C Kombination aus 24,5 Gew.-% Kathon 893, 17,5 Gew.-% Pyrion-Na und 58 Gew.-% Phenoxypropanol

0.28% Kathon 893 (equivalent to 0.126% NOITZ) or the test products were respectively added to the concentrates.

A combination of 24.5% by weight of Kathon 893, 17.5% by weight of Pyrion-Na and 58% by weight of 1-methoxy-2-propanol

B Combination of 24.5% by weight Kathon 893, 17.5% by weight of Pyrion-Na and 58% by weight of phenoxyethanol

C Combination of 24.5% by weight of Kathon 893, 17.5% by weight of Pyrion-Na and 58% by weight of phenoxypropanol

or a combination of Kathon 893 and Pyrion-Na without solubilizer incorporated. The Kathon 893 content is in all the same. The samples were at 40 ° C or Room temperature stored in clear glass and daily about 7 to Stirred for 8 hours. From the optically stable concentrates were prepared with deionized water 4% solutions or emulsions whose NOITZ content was determined by HPLC. Null values were not determined.

Results: N-octytisothiazolone content after storage: Coolant concentrate: SA 2146

After 3 14 22 28 days at 40 ° C Kathon 893 0.01% <0.01% <0.01% A 0.12% 0.10% <0.01% B 0.12% 0.09% <0.01% C 0.13% 0.10% 0.09% to <0.01% Kathon 893 + Pyrion-Na 0.14% 0.12% <0.01%

N-octylisothiazolone content after storage: Coolant concentrate: SA 2146

To 28 days at T Kathon 893 <0.01% A 0.11% B 0.11% C 0.12% Kathon 893 + Pyrion-Na 0.12%

N-octylisothiazolone content after storage : Coolant concentrate: Kutwell 40

After 3 14 22 28 Days at 40 ° C Kathon 893 0.13% 0.11% 0.11% 0.11% 0.11% A 0.13% 0.11% 0.11% 0.10% 0.11% B 0.13% 0.11% 0.11% 0.11% 0.11% C 0.13% 0.11% 0.10% 0.11% 0.11% Kathon 893 + Pyrion-Na 0.13% 0.14% 0.11% 0.10% 0.11%

The concentrates and emulsions plus additives were optical practically unchanged, even after storage. Regarding the Extent of stabilization, the concentrates differed partly due to different compositions. The products A to C differed in the stabilizing Effect of isothiazolone - with the exception of C at Coolant concentrate SA 2146 - not significant, too not versus a separate addition of Kathon 893 and Pyrion-Na.

Example 7 : Bactericide / fungicide for cooling lubricant Stabilization of N-octylisothiazolone with Na-Pyrion, Boko-Teste

A Boko and Lager Boko test (10 days storage of the cooling lubricant) medium concentrate at 40 ° C) was with the samples A, B, C of Example 6 (Preparations based on Kathon 893, Pyrion-Na and Solubilizer), the individual active ingredients and a combination the active ingredients NOITZ (Kathon 893 was used) and Na-pyrion carried out. The preparations or active ingredients were each in the Concentrates incorporated from which then 4% dilutions in Norderstedter town water were used.

Boko result:

preparation Use Conc. Survived vaccine cycles (inoculation with fungal suspension) unsupported cooling lubricant Shell Dromus BX stored cooling lubricant Shell Dromus BX A 0.1% > 12 > 12 0.075% > 12 > 5 0.05% 3 1 0.025% 0 0 B 0.1% > 12 > 12 0.075% > 12 > 12 0.05% 10 > 6 0.025% 0 0 C 0.1% > 12 > 12 0.075% > 11 > 12 0.05% > 11 > 12 0.025% 4 3 Use Conc. Survived vaccine cycles (inoculation with fungal suspension) Kathon 893 Pyrion-Na (40%) unsupported cooling lubricant Shell Dromus BX stored cooling lubricant Shell Dromus BX 0.025% > 12 8th 0.018% 9 3 0.012% 9 2 0.006% 0 1 0.0175% 0 0 0.013% 0 0 0.0087% 0 0 0.004% 0 0 0.025% 0.0175% > 12 > 12 0.018% 0.013% > 12 > 5 0.012% 0.0087% > 12 2 0.006% 0.004% 0 0

The freshly prepared concentrates and the 4% dilutions visually showed no differences to the respective blank value (Coolant without active ingredient). After 10 days storage at 40 ° C showed the drug-containing Shell Dromus BX concentrates and Dilutions optically also no difference to the blank value on. As expected, there was a decline in activity in the stored samples however, comparatively for products B and C. low turned out. In the non-stored samples, the preparation was C most effective or roughly comparable to the effectiveness of Combination Kathon 893 and Pyrion-Na (without solvent). at The stored patterns clearly showed C before B and A the best Effect, which is roughly comparable to the effectiveness of Combination Kathon 893 and Pyrion-Na (without solvent) was.

Pyrion-Na improved the efficacy of Kathon 893 in the Boko test. By combining this drug mixture with a solubilizers according to the invention (in particular phenoxypropanol or phenoxyethanol), the effectiveness in the Boko test was also under practical conditions (e.g., elevated temperature storage, which is an extension of storage at room temperature to come).

The combination: Kathon 893, Pyrion-Na and inventive Solubilizers not only facilitated the handling and Dosage of the agent, it additionally improved the stability and the effectiveness of the biocide mixture.

Claims (16)

1. An additive mixture for cooling-lubricant products, which comprises

   a. a halogen-free isothiazolone of Formula

   

      in which
      Y is a (C₁-C₁₈) alkyl or (C₃-C₁₂) cycloalkyl group, which can be substituted with one or more hydroxy, cyano, alkylamino, dialkylamino, aryl, amino, carboxyl, carbalkoxyl, alkoxy, aryloxy, alkylthio, arylthio, cycloalkylamino, carbamoxy or isothiazolonyl groups, an unsubstituted (C₂-C₈) alkenyl or alkynyl group, a (C₇-C₁₀) aralkyl group, which can be substituted with one or more (C₁-C₄) alkyl or (C₁-C₄) alkoxy groups, or is an aryl group, which can be substituted with one or more nitro, (C₁-C₄) alkyl, (C₁-C₄) alkyl acrylamino, carb-(C₁-C₄) alkoxy or sulfamyl groups, and
      R and R' are each independently hydrogen, a (C₁-C₄) alkyl group, a (C₄-C₈) cycloalkyl group or are linked together to form a benzoisothiazolonyl group,

   b. an effective stabiliser to prevent chemical decomposition of the isothiazolone, selected from 2-mercaptopyridine-N-oxide, metal or ammonium salts of 2-mercaptopyridine-N-oxide, metal salt complexes of 2-mercaptopyridine-N-oxide, 2,2'-dithiobis(pyridine-N-oxide) as well as mixtures thereof, together with an optional co-stabiliser, and

   c. a solubiliser, selected from phenoxyethanol, phenoxypropanols, 1-methoxypropane-2-ol and mixtures thereof.
2. Additive mixture according to Claim 1, characterised in that the solubiliser is comprised in a quantity of 30 to 91.7 wt.% based on the additive mixture.
3. Additive mixture according to Claim 2, characterised in that the solubiliser is comprised in a quantity of 30 to 75 wt.% based on the additive mixture.
4. Additive mixture according to Claim 3, characterised in that the solubiliser is comprised in a quantity of 50 to 65 wt.% based on the additive mixture.
5. Additive mixture according to one of Claims 1 to 4, characterised in that the co-stabiliser is a mild oxidising agent.
6. Additive mixture according to one of Claims 1 to 5, characterised in that the co-stabiliser is selected from iodopropynylbutyl carbamate, hydrogen peroxide, t-butyl peroxide, sodium bromate, Cu(II) salts, 2-tert-butyl-6-methylphenol and pyrione disulfide.
7. Additive mixture according to one of Claims 1 to 6, comprising the following components based on the mixture

   a. 2.25 to 20.25 wt.% N-octylisothiazolone

   b. ca. 1.3 to 10 wt.% sodium salt of mercaptopyridine-N-oxide and

   c. 30 to 91.7 wt.% 2-phenoxyethanol, 2-phenoxypropanol or 1-methoxypropane-2-ol.
8. Additive mixture according to Claim 7, comprising the following components based on the mixture:

   a. 6.75 to 20.25 wt.% N-octylisothiazolone

   b. 4 to 10 wt.% sodium salt of mercaptopyridine-N-oxide and

   c. 30 to 75 wt.% 2-phenoxyethanol, 2-phenoxypropanol or 1-methoxypropane-2-ol.
9. Additive mixture according to Claim 8, comprising the following components based on the mixture:

   a. 9 to 13.5 wt.% N-octylisothiazolone

   b. 6 to 8 wt.% sodium salt of mercaptopyridine-N-oxide and

   c. 50 to 65 wt.% 2-phenoxyethanol, 2-phenoxypropanol or 1-methoxypropane-2-ol.
10. Additive mixture according to Claim 9, comprising the following components based on the mixture:

    a. ca. 11 wt.% N-octylisothiazolone

    b. ca. 7 wt.% sodium salt of mercaptopyridine-N-oxide and

    c. ca. 58 wt.% 2-phenoxyethanol, 2-phenoxypropanol or 1-methoxypropane-2-ol.
11. Cooling lubricant products characterised in that in addition to usual ingredients, they comprise an additive mixture according to one of Claims 1 to 10.
12. Cooling lubricant products according to Claim 11, characterised in that they are concentrates of cooling lubricants or are ready-for-use.
13. Cooling lubricant products according to Claim 11 or 12, characterised in that they are in the form of a solution or an emulsion.
14. Use of an additive mixture according to one of Claims 1 to 10 for the manufacture of cooling lubricant products.
15. Use according to Claim 14, characterised in that a cooling lubricant concentrate is manufactured.
16. Use according to Claim 15, characterised in that a cooling lubricant mixed with water is manufactured.