WO2008068197A1

WO2008068197A1 - Polyisocyanate preparations

Info

Publication number: WO2008068197A1
Application number: PCT/EP2007/063067
Authority: WO
Inventors: Carl Jokisch; Harald Schäfer; Horst Binder
Original assignee: Basf Se
Priority date: 2006-12-04
Filing date: 2007-11-30
Publication date: 2008-06-12

Abstract

The present invention relates to novel, stabilized polyisocyanate preparations.

Description

polyisocyanate preparations

description

The present invention relates to novel stabilized polyisocyanate preparations.

Polyisocyanates which are used for coatings and coatings are generally reaction products of isocyanates, usually of diisocyanates. These are modified by urethanization, urea formation, allophanatization, biuretization, trimerization and dimerization and similar reaction possibilities. The polyisocyanates obtained in this way often contain no or very little free starting isocyanate. But they still contain free NCO groups, which still have a high reactivity, which should be used for later application. However, such polyisocyanate preparations must be stable and stable over long periods of time.

It has therefore already been proposed to stabilize polyisocyanates by adding certain compounds which are generally acidic in character.

EP 341516 B1 describes polyisocyanates which are stabilized with the aid of chloroalkanoic acids comprising at least three carbon atoms. Examples are 2- and 3-chloropropionic acid.

According to EP 341516 B1, a stabilizer is intended to fulfill a number of functions: it should be reaction accelerators and catalysts which were previously used, if appropriate, in reactions or with reaction partners, e.g. Polyethers or polyesters are unintentionally but inevitably introduced, bind and render ineffective;

- It should prevent the polyisocyanate is adversely affected by light or similar external influences and, of course, must not cause even changes such as discoloration; he should ensure that the polyisocyanate remains unchanged and retains its high reactivity;

- It should ensure in the subsequent use of the polyisocyanate that the reactivity to reactants such as polyhydric alcohols or optionally blocked polyamines is reproducible, i. he should also be a catalyst for subsequent reactions.

It is apparent from this that the term "stabilizer" in the present application does not mean the polyurethane foam stabilizers which have long played a major role in isocyanate chemistry and are surface-active agents, for example based on polysiloxanes. US 3914269 describes weak acids with a pKa of 4 to 12 for the decomposition of carbodiimide structures in a reaction mixture of a phosgenation of aromatic amines.

This is a crude, i. undistilled reaction mixture of an aromatic diisocyanate.

In EP 155 559 A1, for example, basic catalysts contained in isocyanurate polyisocyanates are eliminated by acids such as phosphoric acid, dodecylbenzenesulfonic acid, monochloroacetic acid, monofluoroacetic acid or benzoyl chloride and the polyisocyanates are thereby stabilized.

In EP 239 834 A1 and EP-A 254 177, compounds containing urethane-containing polyisocyanates were added such as formic acid, acetic acid, mono-, di- and trichloroacetic acid, oxalic acid, malonic acid, maleic acid, fumaric acid, benzoic acid, mono-, di- and trichlorobenzoic acid , Salicylic acid, toluenesulfonic acid, xylenesulfonic acid and others As a result of this addition, the polyisocyanates mentioned have a constant reactivity toward reactants, such as polyaldimines, with which they react on the admission of moisture, since the additives also influence the hydrolysis rate of the polyaldimines.

EP 643042 A describes the stabilization of a phosgene-free process diisocyanate with a mixture of stabilizers, which also contains acids.

The object of the present invention was to provide further possibilities for the stabilization of polyisocyanates, in particular to reduce an increase in viscosity during storage.

The object was achieved by Polyisocyanatzubereitungen consisting of

at least one polyisocyanate (P),

at least one alkoxyalkanoic acid (A),

- optionally at least one solvent (L) and

- optionally further stabilizers (S).

The polyisocyanates (P) used according to the invention are oligomers of aromatic, aliphatic or cycloaliphatic isocyanates (D), preferably aliphatic or cycloaliphatic, which in this document is referred to briefly as (cyclo) aliphatic, particularly preferred are aliphatic isocyanates.

Aromatic isocyanates are those containing at least one aromatic ring system. Cycloaliphatic isocyanates are those which contain at least one cycloaliphatic ring system.

Aliphatic isocyanates are those which contain exclusively straight or branched chains, ie acyclic compounds.

The isocyanates (D) are preferably diisocyanates which carry exactly two isocyanate groups. In principle, however, it may also be monoisocyanates having an isocyanate group.

In principle, higher isocyanates having an average of more than 2 isocyanate groups are also considered. For example, triisocyanates such as triisocyanato, 2,4,6-triisocyanatotoluene, triphenylmethane triisocyanate or 2,4,4'-triisocyanato-diphenyl ether or the mixtures of di-, tri- and higher polyisocyanates suitable for example by phosgenation of corresponding aniline / Formaldehyde condensates are obtained and represent methylene bridges Polyphenylpolyiso- cyanate.

The diisocyanates are preferably isocyanates having 4 to 20 C-

Atoms. Examples of customary diisocyanates are aliphatic diisocyanates such as tetramethylene diisocyanate, 1,5-pentamethylene diisocyanate, hexamethylene diisocyanate (1,6-diisocyanatohexane), octamethylene diisocyanate, decamethylene diisocyanate, dodecamethylene diisocyanate, tetradecamethylene diisocyanate, derivatives of lysine diisocyanate, trimethylhexane diisocyanate or tetramethylhexane diisocyanate, cycloaliphatic diisocyanates such as 1, 4, 1, 3 or 1, 2-diisocyanatocyclohexane, 4,4'- or 2,4'-di (isocyanatocyclohexyl) methane, 1-isocyanato-3,3,5-trimethyl-5- (isocyanatomethyl) cyclohexane ( Isophorone diisocyanate), 1,3- or 1,4-bis (isocyanatomethyl) cyclohexane or 2,4- or 2,6-diisocyanato-1-methylcyclohexane and also 3 (or 4), 8 (or 9) -bis ( isocyanatomethyl) tricyclo [5.2.1.0 ²⁶ ] decane isomer mixtures, and also aromatic diisocyanates such as 2,4- or 2,6-toluene diisocyanate and their isomer mixtures, m- or p-xylylene diisocyanate, 2,4'- or 4,4'- Diisocyanatodiphenylmethane and their isomer mixtures, 1 , 3- or 1,4-phenylene diisocyanate, 1-chloro-2,4-phenylene diisocyanate, 1,5-naphthylene diisocyanate, diphenylene-4,4'-diisocyanate, 4,4'-diisocyanato-3,3'-dimethyldiphenyl, 3 -Methyldi- phenylmethane-4,4'-diisocyanate, tetramethylxylylene diisocyanate, 1, 4-diisocyanatobenzene or diphenyl ether-4,4'-diisocyanate.

Particular preference is given to 1,6-hexamethylene diisocyanate, 1,3-bis (isocyanatomethyl) cyclohexane, isophorone diisocyanate and 4,4'- or 2,4'-

Di (isocyanatocyclohexyl) methane, most preferred are isophorone diisocyanate and hexamethylene diisocyanate, particularly preferred is hexamethylene diisocyanate. There may also be mixtures of said isocyanates. A preferred mixture is composed of 1, 6-hexamethylene diisocyanate and isophorone diisocyanate.

Isophorone diisocyanate is usually present as a mixture, namely the cis and trans isomers, usually in the ratio of about 60:40 to 80:20 (w / w), preferably in the ratio of about 70:30 to 75:25 and most preferably in the ratio of about 75:25.

Dicyclohexylmethane-4,4'-diisocyanate may also be present as a mixture of the different cis and trans isomers.

For the present invention, it is possible to use both those diisocyanates which are obtained by phosgenation of the corresponding amines and those which can be obtained without the use of phosgene, ie. H. after phosgene-free process, are produced. According to EP-AO 126 299 (US Pat. No. 4,596,678), EP-A-126 300 (US Pat. No. 4,596,679) and EP-A-355 443 (US Pat. No. 5,087,739), for example, (cyclo) aliphatic diisocyanates, eg such as 1,6-hexamethylene diisocyanate (HDI), isomeric aliphatic diisocyanates having 6 carbon atoms in the alkylene radical, 4,4'- or 2,4'-

Di (isocyanatocyclohexyl) methane and 1-isocyanato-S-isocyanato-methyl-S ^^ - trimethylcyclohexane (isophorone diisocyanate or IPDI) are prepared by reacting the (cyclo) aliphatic diamines with, for example, urea and alcohols to (cyclo) aliphatic Biscarbaminsäureestern and their thermal cleavage into the corresponding diisocyanates and alcohols. The synthesis is usually carried out continuously in a cyclic process and optionally in the presence of N-unsubstituted carbamic acid esters, dialkyl carbonates and other by-products recycled from the reaction process. Diisocyanates obtained in this way generally have a very low or even non-measurable proportion of chlorinated compounds, which leads to favorable color numbers of the products.

In one embodiment of the present invention, the diisocyanates (D) have a total hydrolyzable chlorine content of less than 200 ppm, preferably less than 120 ppm, more preferably less than 80 ppm, most preferably less than 50 ppm, especially less than 15 ppm and especially less than 10 ppm. This can be measured, for example, by ASTM D4663-98. However, it is of course also possible to use diisocyanates (D) with a higher chlorine content, for example up to 500 ppm.

Of course, mixtures of such diisocyanates obtained by reaction of the (cyclo) aliphatic diamines with, for example, urea and alcohols and cleavage of the resulting (cyclo) aliphatic biscarbamic acid esters may also be obtained. those with diisocyanates obtained by phosgenation of the corresponding amines.

The polyisocyanates (P) to which the isocyanates (D) can be oligomerized are usually characterized as follows:

The NCO functionality of such compounds is generally at least 1, 8 and may be up to 8, preferably 1, 8 to 5 and particularly preferably 2 to 4.

The content of isocyanate groups after the oligomerization, calculated as NCO = 42 g / mol, is usually from 5 to 25% by weight.

The polyisocyanates (P) are preferably the following compounds:

1) isocyanurate polyisocyanates of aromatic, aliphatic and / or cycloaliphatic diisocyanates. Particular preference is given here to the corresponding aliphatic and / or cycloaliphatic isocyanato-isocyanurates and in particular those based on hexamethylene diisocyanate and isophorone diisocyanate. The isocyanurates present are in particular tris-isocyanatoalkyl or tris-isocyanatocycloalkyl

Isocyanurates, which are cyclic trimers of diisocyanates, or mixtures with their higher, more than one isocyanurate homologues. The isocyanato-isocyanurates generally have an NCO content of 10 to 30 wt .-%, in particular 15 to 25 wt .-% and an average NCO functionality of 2.6 to 8.

2) uretdione diisocyanates having aromatic, aliphatic and / or cycloaliphatic bonded isocyanate groups, preferably aliphatically and / or cycloaliphatically bonded and in particular those derived from hexamethylene diisocyanate or isophorone diisocyanate. Uretdione diisocyanates are cyclic dimerization products of diisocyanates.

The uretdione diisocyanates can be used as the sole component or in a mixture with other polyisocyanates, in particular those mentioned under 1).

3) biuret polyisocyanates having aromatic, cycloaliphatic or aliphatic bound, preferably cycloaliphatic or aliphatic bound isocyanate groups, in particular tris (6-isocyanatohexyl) biuret or mixtures thereof with its higher homologues. These biuret-containing polyisocyanates generally have an NCO content of 18 to 22 wt .-% and an average NCO functionality of 2.8 to 4.5. 4) polyisocyanates containing urethane and / or allophanate groups with aromatically, aliphatically or cycloaliphatically bonded, preferably aliphatically or cycloaliphatically bonded isocyanate groups, as described, for example, by reacting excess amounts of diisocyanate, for example hexamethylene diisocyanate or isophorone diisocyanate, with monohydric or polyhydric alcohols ( O). These urethane and / or allophanate-containing polyisocyanates generally have an NCO content of 12 to 24 wt .-% and an average NCO functionality of 2.5 to 4.5.

5) oxadiazinetrione-containing polyisocyanates, preferably derived from hexamethylene diisocyanate or isophorone diisocyanate. Such oxadiazinetrione-containing polyisocyanates are accessible from diisocyanate and carbon dioxide.

6) polyisocyanates containing iminooxadiazinedione groups, preferably derived from hexamethylene diisocyanate or isophorone diisocyanate. Such iminooxadiazine-dione-containing polyisocyanates can be prepared from diisocyanates by means of special catalysts.

7) Uretonimine-modified polyisocyanates.

8) carbodiimide-modified polyisocyanates.

9) Hyperbranched polyisocyanates, as are known, for example, from DE-A1 10013186 or DE-A1 10013187.

10) polyurethane-polyisocyanate prepolymers of di- and / or polyisocyanates with alcohols.

1 1) polyurea-polyisocyanate prepolymers.

In a preferred embodiment of the present invention, the polyisocyanate (P) is selected from the group consisting of isocyanurates, biurets, urethanes and allophanates, preferably from the group consisting of isocyanurates, urethanes and allophanates, more preferably from the group consisting of isocyanurates and allophanates.

For the preparation of urethanes and / or allophanates, the isocyanates (D) but also polyisocyanates (P) with at least one monohydric or polyhydric alcohol (O) are reacted, such as methanol, ethanol, isopropanol, n-propanol, n-butanol , isobutanol, sec-butanol, tert-butanol, n-hexanol, n-heptanol, n-octanol, n-decanol, n-dodecanol (lauryl alcohol), 2-ethylhexanol, n-pentanol, stearyl alcohol, cetyl alcohol, Lauryl alcohol, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, 1,3-propanediol monomethyl ether, cyclopentanol, cyclohexanol, cyclooctanol, cyclododecanol, trimethylolpropane, neopentyl glycol, pentaerythritol, 1,4-butanediol, 1,6-hexanediol, 1,2-propanediol, 1, 3-propanediol, 2-ethyl-1,3-propanediol, 2-methyl-1,3-propanediol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, glycerol, 1,2-dihydroxypropane, 2,2-dimethyl- 1,2-ethanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, pentane-2,4-diol, 3-methylpentane-1,5-diol, 2,2,4-trimethylpentane 1, 5-diol, 2-methylpentane-2,4-diol, 2-methylpentane-1,3-diol, 2-ethylhexane-1,3-diol, 2-propyl-1,3-heptanediol, 2,4- Diethyloctane-1, 3-diol, hydroxypivalic acid neopentyl glycol ester, ditrimethylolpropane, dipentaerythritol, 2,2-bis (4-hydroxycyclohexyl) propane, 1, 1, 1, 2, 1, 3 and 1, 4-cyclohexanedimethanol, 1 , 2-, 1, 3- or 1, 4-cyclohexanediol or mixtures thereof can be obtained.

The proportion of alcohol (O) can be up to 50% by weight, preferably up to 40, particularly preferably up to 30 and very particularly preferably up to 25% by weight, based on the isocyanate (D).

In a further embodiment of the present invention, only a small proportion of alcohol (O) can be used based on the isocyanate (D), for example 0.25-10% by weight, preferably 0.5-8, particularly preferably 0.75-5 and most preferably 1-3% by weight.

In a preferred embodiment, the alcohol (O) is a compound having at least one, preferably exactly one isocyanate-reactive group and at least one, for example one to six, preferably one to five, particularly preferably one to four and all particularly preferably one, two or three free-radically polymerizable unsaturated groups, preferably acrylate or methacrylate groups.

Isocyanate-reactive groups may be e.g. Hydroxy, mercapto, amino or monosubstituted imino, preferably hydroxy or amino, more preferably hydroxy.

Examples of such compounds are, for example, monoesters of methacrylic acid or preferably acrylic acid with diols or polyols which preferably have 2 to 20 C atoms and at least two hydroxyl groups, such as ethylene glycol, diethylene glycol, triethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol , 1, 1-dimethyl-1, 2-ethanediol, dipropylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, tripropylene glycol, 1, 2, 1, 3 or 1, 4-butanediol, 1, 5-pentanediol, neopentyl glycol, 1 , 6-hexanediol, 2-methyl-1, 5-pentanediol, 2-ethyl-1, 4-butanediol, 1, 4-dimethylolcyclohexane, 2,2-bis (4-hydroxycyclohexyl) propane, glycerol, trimethylolethane, trimethylolpropane, trimethylol butane, pentaerythritol, ditrimethylolpropane, erythritol, sorbitol, poly-THF with a molecular weight weight between 162 and 2000, poly-1,3-propanediol having a molecular weight between 134 and 400, or polyethylene glycol having a molecular weight between 238 and 458.

Preference is given to 2-hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) acrylate, 1,4-butanediol mono (meth) acrylate, neopentyl glycol mono (meth) acrylate, 1, 5

Pentanediol mono (meth) acrylate, 1,6-hexanediol mono (meth) acrylate, glycerol mono- and di (meth) acrylate, trimethylolpropane mono- and di (meth) acrylate, pentaerythritol mono-, di- and tri (meth) acrylate, 2- Aminoethyl (meth) acrylate, 2-aminopropyl (meth) acrylate, 3-aminopropyl (meth) acrylate, 4-aminobutyl (meth) acrylate, 6-aminohexyl (meth) acrylate or 2-thioethyl (meth) acrylate. Particularly preferred are 2-hydroxyethyl acrylate, 2-

Hydroxyethyl methacrylate, 2- or 3-hydroxypropyl acrylate, 1, 4-butanediol monoacrylate, 3- (acryloyloxy) -2-hydroxypropyl (meth) acrylate and the monoacrylates of polyethylene glycol of molecular weight from 106 to 238.

The unreacted isocyanate is usually separated from the polyisocyanate after its preparation, preferably via a thin-film distillation.

After separation, the content of unreacted, monomeric isocyanate in the polyisocyanate (P) is generally below 1% by weight, preferably below 0.7% by weight, more preferably below 0.5% by weight, very particularly preferably below 0.3% by weight. and in particular less than 0.1% by weight.

Alkoxyalkanoic Acid (A)

The alkoxyalkanoic acid (A) used in accordance with the invention is alkanecarboxylic acids which carry one or more alkyloxy radicals, preferably an alkoxy radical.

The alkanecarboxylic acids are preferably from 1 to 10, preferably 2 to 6, more preferably 2 to 4, most preferably 2 or 3 carbon atoms straight-chain or branched alkanecarboxylic acids.

Examples of such alkanecarboxylic acids are formic acid, acetic acid, propionic acid, n-butanoic acid, isobutyric acid, pentanoic acid, 2-methylpentanoic acid, n-hexanoic acid, 2-ethylhexanoic acid or 3-propylheptanoic acid, preferably acetic acid, propionic acid, n-butanoic acid or isobutyric acid, particularly preferably acetic acid or propionic acid and most preferably acetic acid.

The alkyl groups of the alkyloxy radicals preferably have 1 to 4, particularly preferably 1 to 3, very particularly preferably 1 to 2 and in particular 1 carbon atom. Examples are methoxy, ethoxy, isopropoxy, n-propoxy, n-butoxy, isobutoxy, sec-butoxy and tert-butoxy, preferred are methoxy, ethoxy, isopropoxy and n-butoxy, particularly preferred are methoxy and ethoxy and most preferred is methoxy.

Exemplary individuals are 3-methoxybutanoic acid, 3-methoxypropanoic acid, 2-methoxypropanoic acid, 3-methoxy-2-methylpropanoic acid, methoxyacetic acid, 3-ethoxybutanoic acid, 3-ethoxypropanoic acid, 2-ethoxypropanoic acid, 3-ethoxy-2-methylpropanoic acid and ethoxyacetic acid.

Preference is given to 3-methoxypropanoic acid, 2-methoxypropanoic acid, methoxyacetic acid, 3-ethoxypropanoic acid and ethoxyacetic acid; particularly preferred are 3-methoxypropanoic acid, 2-methoxypropanoic acid, methoxyacetic acid and ethoxyacetic acid, very particular preference is given to ethoxyacetic acid and methoxyacetic acid and in particular methoxyacetic acid.

Preferred alkyloxyalkanecarboxylic acids (A) have a pKa in the aqueous system of from 2.5 to 4.5, preferably from 2.75 to 4.0.

Further preferred alkyloxyalkanecarboxylic acids (A) have a logP of from -1 to +1, preferably from -0.75 to +0.75.

The calculations of logP values are carried out with the program Molgen 3.0, Evaluation Copy, © 1994 P. Baricic, M. Mackov. The calculation of the logP values is carried out after optimization of the structures with an MM2 force field using the Crippen fragmentation method as described in A.K. Ghose, A. Pritchett, G.M. Crippen, J. Comput. Chem., 9, 80-90, 1988.

Further preferred Alkyloxyalkancarbonsäuren (A) have a solubility in the polyisobutene cyanate (P) at 25 ⁰ C of at least 100 ppm by weight to, preferably at least 1 wt%. Are the polyisocyanates at 25 ⁰ C fixed, so the solubility refers to solutions of the polyisocyanates (P) in the solvent (L).

The addition of the alkyloxyalkanecarboxylic acid (A) is generally carried out in the already prepared polyisocyanates (P) after distillative removal of the monomeric isocyanate. For this purpose, the desired amount of Alkyloxyalkancarbonsäure (A), optionally dissolved or suspended in a solvent under shear with the polyisocyanate (P), which may already be in the solvent (L), if present, dissolved, united. This can be done, for example, by metering the alkyloxyalkanecarboxylic acid (A) into a pump, for example into a filling or circulating pump. If desired, the pump may be followed by a static mixer, which is usually not necessary. The addition is preferably carried out at room temperature (23 ⁰ C) to 30 ⁰ C.

However, it is also possible, although less preferred, to deactivate with the alkyloxyalkanecarboxylic acid (A) a catalyst required for the preparation of the polyisocyanate (P) from the isocyanate:

For this purpose, after reaching the desired degree of conversion of the isocyanate to the polyisocyanate (P), the reaction is stopped by deactivating the catalyst by adding the compound (A). The conversion can be chosen differently depending on the isocyanate used. In general, a conversion of 10 to 60% (based on the NCO content before the reaction) is desired, preferably 10 to 40%. The addition of the Alkyloxyalkancarbonsäure (A) is usually carried out at the reaction temperature, but can also be carried out at higher or lower temperature, for example up to 30 ⁰ C lower, preferably up to 20 ⁰ C lower and more preferably up to 10 ⁰ C lower. To stop the reaction, the compound (A) in a molar ratio of, for example, 0.5 to 30, more preferably from 0.6 to 3, most preferably 0.8 to 2, based on the amount of catalyst used.

Solvent (L)

The polyisocyanate preparation may optionally contain at least one solvent in which the resulting polyisocyanate (P) is formulated after removal of the unreacted isocyanate (D). It would also be conceivable that the preparation of the polyisocyanate (P) from the isocyanate (D) in a solvent (L) is performed. In the latter case, the solvent (L) can be distilled off with the isocyanate (D) or the mixture of polyisocyanate (P), isocyanate (D) and solvent (L) can be further used.

Examples of such solvents are aromatic and / or (cyclo) aliphatic hydrocarbons and mixtures thereof, halogenated hydrocarbons, esters and ethers.

Preference is given to aromatic hydrocarbons, (cyclo) aliphatic hydrocarbons, alkanoic acid alkyl esters, alkoxylated alkanoic acid alkyl esters and mixtures thereof.

Particularly preferred are mono- or polyalkylated benzenes and naphthalenes, Alkansäurealkylester and alkoxylated Alkansäurealkylester and mixtures thereof.

Preferred aromatic hydrocarbon mixtures are those which comprise predominantly aromatic C 7 - to C 20 -hydrocarbons and may have a boiling range of from 10 to 300 ^° C., particular preference is given to toluene, o-, m- or p- XyIoI, trimethylbenzene isomers, tetramethylbenzene isomers, ethylbenzene, cumene, tetrahydronaphthalene and mixtures containing such.

Examples include Solvesso® brands from ExxonMobil Chemical, Particularly Solvesso® 100 (CAS No. 64742-95-6, predominantly _C9 and Cio aromatics, boiling range about 154 -. 178 ⁰ C), 150 (boiling range about 182 -. 207 ⁰ C) and 200 (CAS No. 64742-94-5), Shellsol® grades from Shell, Caromax® (eg Caromax® 18) from Petrochem Carless and hydrosol from DHC (eg as hydrosol ® A 170). Hydrocarbon mixtures of paraffins, cycloparaffins and aromatics are also available under the designations crystal oil (for example, crystal oil 30, boiling range about 158-198 ⁰ C or crystal oil. 60: CAS No. 64742-82-1), petroleum spirit (for example likewise CAS No. 64742-. 82-1) or solvent naphtha (light: boiling range about 155-180 ⁰ C, heavy: boiling range about 225-300 ⁰ C) commercially available. The aromatic content of such hydrocarbon mixtures is generally more than 90% by weight, preferably more than 95, more preferably more than 98% and very particularly preferably more than 99% by weight. It may be useful to use hydrocarbon mixtures with a particularly reduced content of naphthalene.

The content of aliphatic hydrocarbons is generally less than 5, preferably less than 2.5 and more preferably less than 1% by weight.

Halogenated hydrocarbons are, for example, chlorobenzene and dichlorobenzene or isomeric mixtures thereof.

Esters include, for example, n-butyl acetate, ethyl acetate, 1-methoxypropyl acetate-2 and 2-methoxyethyl acetate.

Ethers are, for example, THF, dioxane and the dimethyl, ethyl or n-butyl ethers of ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol or tripropylene glycol.

Examples of (cyclo) aliphatic hydrocarbons are decalin, alkylated decalin and isomer mixtures of straight-chain or branched alkanes and / or cycloalkanes, for example petroleum ether or ligroin.

Preference is furthermore given to n-butyl acetate, ethyl acetate, 1-methoxypropyl acetate-2,2-methoxyethyl acetate, and mixtures thereof, in particular with the abovementioned aromatic hydrocarbon mixtures.

Such mixtures can be prepared in a volume ratio of 5: 1 to 1: 5, preferably in a volume ratio of 4: 1 to 1: 4, more preferably in a volume ratio of 3: 1 to 1: 3 and most preferably in a volume ratio of 2: 1 to 1: 2 , Preferred examples are butyl acetate / xylene, methoxypropyl acetate / xylene 1: 1, butyl acetate / solvent naphtha 100 1: 1, butyl acetate / Solvesso® 100 1: 2 and crystal oil 30 / Shellsol® A 3: 1.

Other stabilizers (S)

The other stabilizers may be primary or secondary stabilizers.

Primary stabilizers (S1) are those compounds which are usually active as antioxidant and / or radical scavenger. Suitable primary stabilizers for the purposes of the invention are preferably phenolic antioxidants, ie compounds which contain at least one sterically hindered phenolic group.

Examples of phenolic antioxidants which may be mentioned are 2,6-di-tert-butyl-4-methylphenol, 2,4,6-tri-t-butylphenol, 2,2'-methylene-bis- (4-methyl-6-tert-butylphenol) butylphenol), 2,2'-thiobis (4-methyl-6-t-butylphenol), 4,4'-thio-bis (3-methyl-6-t-butylphenol), 4,4'-butylidene bis (6-t-butyl-3-methylphenol), 4,4'-methylidenebis (2,6-di-t-butylphenol), 2,2'-methylenebis [4-methyl-6 - (1-methylcyclohexyl) phenol], tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) -propionate] methane, 1, 3,5-trimethyl-2,4,6- tris (3, 5-d it-butyl-4-hydroxybenzyl) benzene, N, N'-hexamethylene bis (3,5-di-t-butyl-4-hydroxyhydrocinnamic acid amide), octadecyl-3- (3, 5-di-t-butyl-4-hydroxyphenyl) propionate, 1,3,5-tris (3,5-di-t-butyl-4-hydroxybenzy1) isocyanurate, 1,1,3 tris ( 5-t-butyl-4-hydroxy-2-methylphenyl) butane, 1, 3,5-tris (3,5-di-t-butyl-4-hydroxybenzyl) mesitylene, ethylene glycol bis [3,3 bis (3'-t-butyl-4'-hydroxyphenyl) butyrate], 2,2'-thiodiethyl-bis-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, di- ( 3-t-butyl-4'-hydr oxy-5-methylphenyl) dicyclopentadiene, 2,2'-methylenebis (4-methyl-6-cyclohexylphenol), 1,6-hexanediol-bis (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,4-bis (n-octylthio) -6- (4-hydroxy-3,5-di-t-butylanilino) -1, 3,5-triazine, 3,5-di-t-butyl-4 hydroxybenzylphosphonic acid diethyl ester and triethylene glycol bis-3- (t-butyl-4-hydroxy-5-methylphenyl) propionate.

Have proven to be excellent and therefore preferably used are, for example, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2'-methylenebis (4-methyl-6-cyclohexylphenol), 2,2'-methylenebis (4-methyl-6-t.butylphenol), triethylene glycol bis-3- (t-butyl-4-hydroxy-5-methylphenyl) propionate, tetrakis [methylene-3 - (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane and especially 2,6-di-t-butyl-4-methylphenol and 3,5-di-tert-butyl-4-hydroxy anisole. Other primary stabilizers which can be used are nitrogen-containing stabilizers, preferably aromatic amines substituted by alkyl, cycloalkyl and / or aryl radicals, for example 4,4'-di-t.octyldiphenylamine, 4,4'-di- (α, α-dimethylbenzyl ) -diphenylamine, phenyl-.beta.-naphthylamine, N-isopropyl-N'-phenyl-p-phenylenediamine, N-phenyl-2-naphthylamine and / or phenyl-2-aminonaphthalene.

The sterically hindered phenols and aromatic amines can each be used individually or in the form of mixtures. It is also possible to use mixtures of at least one sterically hindered phenol and at least one aromatic amine.

As secondary stabilizers (S2) which can be used as sole stabilizers or preferably together with the primary stabilizers, it is expedient to use compounds which are usually active as peroxide splitter and / or reducing agent. Suitable secondary stabilizers according to the invention are e.g. phosphorus-containing compounds, preferably triesters of phosphorous acid, e.g. Trialkyl phosphites and triaryl phosphites, and thioethers.

As secondary stabilizers, phosphorous acid esters, e.g. Distearyl pentaerythritol diphosphite, tris (nonylphenyl) phosphite, tetrakis (2,4-di-t-butylphenyl-4,4'-biphenylene diphosphonite, tris (2,4-di-t-butylphenyl) phosphite, neophen - Tylglykoltriethylenglykol diphosphite, diisodecylpentaerythritol diphosphite, Tristea- rylphosphit, Trilaurylphosphit, Diisodecylphenylphosphit, Tributylphosphit, Trioc- tylphosphit and triphenyl phosphite, which is preferably used, proven.

Examples of suitable thioethers which may be mentioned are: 2-methyl-1-propenyl tert-dodecyl thioether, cyclohexylidenemethyl n-dodecyl thioether, 3-cyclohexen-1-ylidenemethyl-n-octadecyl thioether, 3-cyclohexene-1-ylidenemethyl ether. n-dodecylthioethers, 3-cyclohexeno (1) -ylidenemethyl-n-octylthioethers, 3-cyclohexeno (1) -ylidenemethylcyclohexylthioethers, 3-methyl- (3) -cyclohexeno (1) -ylidenemethyl-n- dodecylthioether, 3-cyclohexeno (1) -ylidene-methyl-p-tolylthioether, 3-cyclohexeno (1) -ylidenemethylbenzylthioether, and preferably 3-cyclohexeno (1) -ylidenemethyl-n-dodecylthioether and 1 -hexenyl-n -dodecylthioether.

The secondary stabilizers from the group of organic phosphites and thioethers which are suitable according to the invention can, like the primary stabilizers, be used individually or mixed with one another. However, it is also possible to use mixtures of at least one organic phosphite and at least one thioether.

The polyisocyanate preparations are usually composed as follows:

Polyisocyanate (P): 30 to 99.99% by weight, preferably 50 to 99.9, more preferably 70 to 95 and most preferably 75 to 90% by weight,

Alkoxyalkanoic acid (A): 1 to 1000 ppm, preferably 20 to 600 ppm and in particular 100 to 400 ppm, based on the weight of the polyisocyanate (P),

Solvent (L): 0 to 70% by weight, preferably 0 to 50% by weight, more preferably 5 to 30 and very particularly preferably 10 to 25% by weight,

Stabilizers (S): primary stabilizer (S1): 0 to 1000 ppm, preferably 20 to 500 ppm and in particular 50 to 200 ppm, based on the weight of the polyisocyanate (P) and / or secondary stabilizer (S2): 0 to 1000 ppm , preferably 20 to 800 ppm and in particular 100 to 400 ppm, based on the weight of the polyisocyanate (P), with the proviso that the sum always yields 100% by weight.

In minor amounts, catalyst traces from the production of the polyisocyanate and optionally the catalyst used to stop the reaction, as well as residues of unreacted isocyanate can be contained in the preparation.

The polyisocyanate preparations according to the invention can be used for the production of polyurethanes and polyurethane paints, for example for one-component, two-component, radiation-curable or powder coating coatings for coating various substrates, such. As wood, wood veneer, paper, cardboard, cardboard, textile, leather, nonwoven, plastic surfaces, glass, ceramics, mineral building materials, metals or coated metals.

When used in coating compositions, the inventive polyisocyanate preparations can be used in particular in primers, fillers, (pigmented) topcoats, basecoats and clearcoats in the field of car repair or large-vehicle painting. Such coating compositions are particularly suitable for applications in which particularly high application safety, outdoor weathering resistance, appearance, solvent resistance, chemical resistance and water resistance are required, such as in vehicle refinish and large vehicle painting.

Such coating compositions are suitable as or in exterior coatings, ie those applications that are exposed to daylight, preferably of building parts, interior coatings, coatings on (large) vehicles and aircraft and industrial applications, bridges, buildings, electricity pylons, tanks, containers, pipelines, Power plants, chemical plants, ships, cranes, piles, sheet piling, fittings, pipes, fittings, flanges, couplings, halls, roofs and structural steel. In particular, the coating compositions of the invention are used as or in automotive clearcoat and topcoat (s). Further preferred fields of application are can coating and coil coating. They are particularly suitable as primers, fillers, pigmented topcoats and clearcoats in the field of industrial, wood, automotive, in particular OEM paintwork, or decorative lacquering. The coating compositions are particularly suitable for applications in which particularly high application safety, outdoor weathering resistance, appearance, scratch resistance, solvent resistance and / or chemical resistance are required. Due to their low color number and high color stability, they are of particular interest for coating compositions for clearcoats.

The inventively stabilized Polyisocyanatzubereitungen show during storage a lower increase in viscosity than unstabilized Polyisocyanatzubereitungen and a slightly improved color.

Examples

After a phosgene process prepared 1,6-hexamethylene diisocyanate (HDI) was in a continuous system with 60 ppm DABCO® TMR (10% in ethanediol) from Air Products at a temperature of 80 ⁰ C to an NCO value of 41% tri - Merisiert and the reaction by heating the reaction mixture to 140 ⁰ C stopped. The unreacted HDI was removed by distillation from the product, which then had a monomer content of 0.1%. Subsequently, ozone was passed through the product for one hour at 80 ° C.

A portion of the product was treated at room temperature (23 ⁰ C) with 300 ppm methoxyacetic acid and stored at 50 ⁰ C for 10 weeks. Another part was stored at 50 ° C without added acid.

While the addition of acid has only a slight positive influence on the color number of the product, the viscosity of the product without addition of acid increases much more than that of the stabilized product.

Claims

claims

1. Polyisocyanate preparations consisting of

at least one polyisocyanate (P), at least one alkoxyalkanecarboxylic acid (A),

- optionally at least one solvent (L) and

- optionally further stabilizers (S).

2. Polyisocyanate preparations according to claim 1, characterized in that it is in the polyisocyanate (P) are oligomers of aliphatic or cycloaliphatic isocyanates (D).

3. Polyisocyanate preparations according to claim 1 or 2, characterized in that the isocyanate (D) is selected from the group consisting of 1, 6-hexamethylene diisocyanate, 1, 3-bis (isocyanatomethyl) cyclohexane, isophorone diisocyanate and 4,4 '- or 2,4'-di (isocyanatocyclohexyl) methane.

4. Polyisocyanate preparations according to one of the preceding claims, characterized in that the polyisocyanate (P) is selected from the group consisting of isocyanurates, biurets, urethanes and allophanates.

5. Polyisocyanate preparations according to Claim 4, characterized in that the polyisocyanate is a urethane or allophanate, for the preparation of which the isocyanates (D) are reacted with at least one monohydric or polyhydric alcohol (O).

6. Polyisocyanate preparations according to one of the preceding claims, characterized in that the alkoxyalkanecarboxylic acid (A) is a straight-chain or branched alkanecarboxylic acid having 1 to 10 carbon atoms substituted by one or more 1 to 4 carbon atoms.

7. Polyisocyanate preparations according to one of the preceding claims, characterized in that the alkoxyalkanecarboxylic acid (A) is selected from the group consisting of 3-methoxybutanoic acid, 3-methoxypropanoic acid, 2-methoxypropanoic acid, 3-methoxy-2-methylpropanoic acid, methoxyacetic acid, 3 Ethoxybutanoic acid, 3-ethoxypropanoic acid, 2-ethoxypropanoic acid, 3-ethoxy-2-methylpropanoic acid and ethoxyacetic acid.

8. Polyisocyanate preparations according to claim 6, characterized in that the alkoxyalkanecarboxylic acid (A) has a pKa value in the aqueous system of 2.5 to 4.5.

9. Polyisocyanate preparations according to claim 6, characterized in that the alkoxyalkanecarboxylic acid (A) has a logP value of -1 to +1.

10. Polyisocyanate preparations according to one of the preceding claims, characterized in that at least one primary stabilizer (S1) is present, which is a compound which acts as antioxidant and / or radical scavenger.

1 1. Polyisocyanate preparations according to one of the preceding claims, characterized in that at least one secondary stabilizer (S2) is present, which is a compound which acts as a peroxide splitter and / or reducing agent.

12. Polyisocyanate preparations according to one of the preceding claims, characterized in that it is composed as follows: - polyisocyanate (P): 30 to 99.99% by weight

Alkoxyalkanoic acid (A): 1 to 1000 ppm, based on the weight of the polyisocyanate (P),

Solvent (L): 0 to 70% by weight,

Stabilizers (S): primary stabilizer (S1): 0 to 1000 ppm based on the weight of the polyisocyanate (P) and / or secondary stabilizer (S2): 0 to 1000 ppm based on the weight of the polyisocyanate (P) with which The proviso that the sum always yields 100% by weight.

13. Use of polyisocyanate preparations according to one of the preceding claims for the production of polyurethanes and polyurethane coatings, for one-component, two-component, radiation-curable or powder coating coatings for coating wood, wood veneer, paper, cardboard, textile, leather, fleece, plastic surfaces, Glass, ceramics, mineral building materials, metal or coated metals.

14. Use of alkoxyalkanecarboxylic acids (A) for stabilizing polyisocyanates.

15. Use of alkoxyalkanecarboxylic acids (A) as catalyst poison for stopping the oligomerization of aromatic, aliphatic or cycloaliphatic isocyanates (D) to give polyisocyanates (P).