WO2007020200A1

WO2007020200A1 - Method for the production of (meth)acrylic acid esters

Info

Publication number: WO2007020200A1
Application number: PCT/EP2006/065046
Authority: WO
Inventors: Hermann Bergmann; Frank HÖFER
Original assignee: Basf Aktiengesellschaft
Priority date: 2005-08-18
Filing date: 2006-08-03
Publication date: 2007-02-22
Also published as: DE102005039536A1

Abstract

Disclosed are a method for producing partially esterified (meth)acrylic acid esters of diols comprising different hydroxy groups, a method for the production thereof, and the use thereof.

Description

Process for the preparation of (meth) acrylic esters

description

The present invention relates to a process for the preparation of partially esterified (meth) acrylic acid esters of diols having different hydroxy groups. Process for their preparation and their use.

The preparation of (meth) acrylic esters is usually carried out by acid or base-catalyzed esterification of (meth) acrylic acid or transesterification of other (meth) acrylic acid esters with alcohols.

Partially esterified (meth) acrylic acid esters of diols having different hydroxyl groups can generally not be prepared in a targeted manner by esterification or transesterification, since statistical mixtures are obtained.

Base-catalyzed transesterification or other syntheses often produce complex and sometimes colored product mixtures. In order to remove stains and unreacted reactants, the product mixtures must be worked up by complex alkaline processes.

German patent application DE 10 2004 033555 discloses an enzymatic process for the preparation of partially esterified (meth) acrylic acid esters of polyhydric alcohols having different hydroxy groups.

The disadvantage is that for enzymes must be used as catalysts, which are expensive and can be used only in a narrow temperature range. In addition, there is a need to use mostly high excesses of an educt in order to obtain acceptable yields, whereby there is a need to separate this excess again. In addition, this reduces the space-time yield.

JP 11-269129 describes the separation of production-resulting product mixtures from the (meth) acrylation of polyols with supercritical CO2.

The disadvantage of this is that JP 11-269129 offers no technical solution to prevent product mixtures, but only separates the resulting product mixtures. As polyols, only diols with equivalent hydroxy groups or polyols with more than two hydroxyl groups are listed.

JP 55-157632 describes the preparation of monoesters of 2,2,4-trimethyl-1,3-pentanediol for use in resin films. As acids for esterification, internal Acrylic acid and methacrylic acid are listed in the long list, but there are no statements on the selectivity or the control of the selectivity.

JS Nelson and TH Applewhite, in Journal of the American OiI Chemists ¹ Society, 1966, 43 (9), 542-5, disclose the transesterification of 12-hydroxystearyl alcohol with methyl acrylate in the presence of para-toluenesulfonic acid. The product obtained is the product monoacrylized at the primary hydroxyl group in position 1 in admixture with the starting diol in which virtually no diacrylate has been formed. Esterification with acrylic acid unselectively led to a mixture of mono- and diacrylates.

The disadvantage is that the product mixtures either, as in the esterification, unselectively lead to mixtures of mono- and diacrylates or, as in the transesterification, are contaminated with the starting diol, which requires a complicated purification.

KL Shantha, G. Pratap, VS Bhaskar Rao and N. Krishnamurti describe in the Journal of Applied Polymer Science, 1990, 41, 945-954 the monoacrylization of long-chained 1, 6- and 1, 7-dihydroxyalkanes in the presence of para toluene sulfonic acid.

The disadvantage is that under the specified reaction conditions despite treatment with activated carbon strongly colored products are obtained.

It was an object of the present invention to provide a process by which partially esterified (meth) acrylic esters of diols with different hydroxy groups can be prepared in high conversions and high selectivities with respect to the reaction at the different hydroxyl groups and high purities from simple starting materials , The synthesis should proceed under mild conditions so that products with a low color number and high purity result. In addition, protective groups should be dispensed with, as well as the use of activated (meth) acrylic acid derivatives, such as, for example, monooximes, vinyl (meth) acrylate, (meth) acrylic anhydride or (meth) acryloyl chloride, and the use of enzymes.

The object was achieved by a process for the preparation of partially esterified (meth) acrylic acid esters (F) having a color number according to DIN ISO 6271 below 500 APHA and a proportion of di (meth) acrylate in the sum of mono- and di (meth) acrylate Diols (C) of less than 5% by weight of divalent aliphatic diols (C) containing different hydroxy groups, characterized in that

either (1) at least one diol (Ci) having a primary hydroxy group and a secondary hydroxy group, or

(2) at least one diol (C2) having a primary hydroxy group and a tertiary hydroxy group, or

(3) at least one diol (C3) having a secondary hydroxy group and a tertiary hydroxy group, wherein the higher-substituted hydroxy group in position β carries at least one alkyl, cycloalkyl, aryl or aralkyl radical, or

(4) at least one diol (C ₄ ) having two primary hydroxy groups, one of which carries at least one in position β and no alkyl, cycloalkyl, aryl or aralkyl radical in position β, or

(5) at least one diol (C5) having two secondary hydroxy groups, one of which carries at least one in position β and no alkyl, cycloalkyl, aryl or aralkyl radical in position β, in the presence of at least one catalyst (S) with ( Meth) acrylic acid esterified or transesterified at least one (meth) acrylic ester (D), wherein the catalyst (S) in the case of a transesterification of the diol (C) with at least one (meth) acrylic acid ester (D) is selected from the group consisting of

- (S1) inorganic salts,

(S2) metal salts having at least one cation selected from the group of alkaline earth metals, tin or titanium,

- (S3) alkali metal salts of Ci to Cβ-alkanolates, and in the case of esterification of the diol (C) with (meth) acrylic acid is selected from

- (S4) acids with a pKa of 0 to 3.

Preference is given to transesterification.

With the aid of the process according to the invention, it is possible to produce partially esterified (meth) acrylic esters (F) in high chemical and space-time yield and under mild conditions with good color numbers without protective group operations and activated (meth) acrylic acid derivatives and using simple catalysts. The term "partially esterified" here denotes that the reaction product obtained by the process according to the invention contains predominantly monoesters in addition to a few steresters (see below), that is to say predominantly a simple esterified product.

(Meth) acrylic acid in this specification stands for methacrylic acid and acrylic acid, preferably for acrylic acid.

Diols (C) useful in this invention are aliphatic diols, i. Both hydroxy groups are bonded to carbon atoms which are aliphatic, ie not constituents of a saturated, unsaturated or aromatic ring system. Although aromatic or cycloaliphatic substituents in the diol (C) may be present, but they do not carry hydroxyl groups.

These diols (C) useful in this invention have distinguishable hydroxy groups, i. According to the invention, they have a lower-substituted and a higher-substituted hydroxy group in the same molecule. Due to the different environment, i. different substituents on the adjacent atoms within the molecule, the hydroxy groups are these in a catalytic (meth) acrylation under mild conditions distinguishable bar, so that according to the inventive method, a higher selectivity achieved than with the known from the prior art Method.

By lower and higher substitution is meant the number of substituents on the carbon atom to which the respective hydroxy group is linked, that is to say on the α-carbon atom (see below).

Lower-substituted hydroxy groups are, for example, primary or secondary hydroxyl groups, higher-substituted hydroxy groups are, for example, secondary or tertiary hydroxyl groups. Therein, the degree of substitution refers to the number of non-hydrogen atoms associated with the carbon atom associated with the hydroxy group under consideration.

Thus, primary hydroxy groups are hydroxy groups bound to exactly one carbon atom attached to just one other carbon atom. Analogously, in the case of secondary hydroxyl groups, the carbon atom bound to it is correspondingly bonded to two and to tertiary hydroxyl groups having three carbon atoms. The diols (C) have a lower-substituted hydroxy group and a higher-substituted hydroxy group.

An additional inventive feature is the presence of at least one alkyl, cycloalkyl, aryl or aralkyl radical in position β to the higher-substituted hydroxy group, preferably at least one alkyl, cycloalkyl or aralkyl radical in position ß, particularly preferably are exclusively alkyl radicals.

The general convention is that the carbon atom to which the hydroxy group is related is the α carbon atom, the next but one is the β carbon atom and then the y carbon atom, as shown schematically below (any substituents are not drawn ):

OH

Preferred diols are either

(1) Diols (Ci) having a primary hydroxy group and a secondary hydroxy group, or

(2) diols (C ₂ ) having a primary hydroxy group and a tertiary hydroxy group, or

(3) diols (C ₃ ) having a secondary hydroxy group and a tertiary hydroxy group, or

(4) diols (C ₄ ) having two primary hydroxy groups, one of which bears at least one in position β and one in position β does not bear any alkyl, cycloalkyl, aryl or aralkyl radical, or (5) diols (Cs) with two secondary Hydroxy groups, one of which carries at least one in position ß and one in position ß no alkyl, cycloalkyl, aryl or aralkyl radical. Among these, particularly preferred are diols (Ci) and (C ₂ ) and very particularly preferred are diols (Ci).

Particular preference is given to diols (C) of the formulas I.

and formula II,

and formula IM

wherein

R ¹ and R ³ to R ^{10 are} each independently hydrogen, Ci - Ci8-alkyl, optionally interrupted by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino C ₂ - Ciβ-alkyl, C ₆ - _Ci2 aryl, C ₅ - Ci ₂ cycloalkyl or a five- to six-membered,

Oxygen, nitrogen and / or sulfur atoms containing heterocycle, wherein said radicals may each be substituted by aryl, alkyl, aryloxy, alkyloxy, heteroatoms and / or heterocycles, and

R ² is a single bond, Ci-C ₂ o-alkylene, _C5-Ci2 cycloalkylene, _{C6-Ci2-arylene} or by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups and / or by one or more cycloalkyl-, - (CO) -, -O (CO) O-, - (NH) (CO) O-, -O (CO) (NH) -, -O (CO) - or - (CO) O- groups interrupted C ₂ -C ₂ o-alkylene, wherein said radicals each by Aryl, alkyl, aryloxy, alkyloxy, heteroatoms and / or heterocycles may be substituted,

mean,

in which

in the case (1) in formula IR ^{1 is} hydrogen and at least one of the radicals R ³ to R ^{7 is} not hydrogen,

for the case (2) in formula II R ^{1 is} hydrogen and at least one of the radicals R ³ to R ^{10 is} different from hydrogen and

for the case (3) in formula II R ¹ is not hydrogen and at least one of the radicals R ³ to R ¹⁰ is not hydrogen,

in case (4) in formula IM R ¹ and R ⁵ are hydrogen and at least one of R ³ and R ^{4 is} not hydrogen and

for the case (5) in formula MI R ¹ and R ^{5 are} different from hydrogen and at least one of the radicals R ³ and R ^{4 is} not hydrogen.

The radicals R ¹ to R ¹⁰ have no further hydroxyl and / or amino groups, particularly preferably the radicals R ¹ to R ¹⁰ have no hydroxyl and / or amino and / or ester and / or amide groups, and very particularly preferably the radicals R ¹ to R ¹⁰ have no further oxygen and / or nitrogen atoms.

Particularly preferably, the radicals R ¹ and R ³ to R ¹⁰ are hydrogen or hydrocarbons, ie they contain exclusively carbon and hydrogen.

Particularly preferably, the radical R ² is a single bond or a hydrocarbon and the radicals R ³ to R ¹⁰ is a hydrocarbon.

In the above definitions mean

optionally substituted by aryl, alkyl, aryloxy, alkyloxy, heteroatoms and / or heterocycles C 1 -C 20 -alkylene, for example methylene, 1, 1-ethylene, 1, 2-ethylene, 1, 1-propylene, 1, 2-propylene, 1, 3-propylene, 1, 1-butylene, 1, 2-butylene, 1, 3-butylene, 1, 4 Butylene, 1,6-hexylene, 2-methyl-1,3-propylene, 2-ethyl-1,3-propylene, 2,2-dimethyl-1,3-propylene, 2,2-dimethyl-1,4 butylene,

optionally substituted by aryl, alkyl, aryloxy, alkyloxy, heteroatoms and / or heterocycles substituted _{_C5-Ci2} cycloalkylene, for example cyclopropylene, cyclopentylene, cyclohexylene, cyclooctylene, cyclododecylene,

optionally substituted by aryl, alkyl, aryloxy, alkyloxy, heteroatoms and / or heterocycles, by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups and / or by one or more cycloalkyl, - (CO) -, -O (CO) O-, - (NH) (CO) O-, -O (CO) (NH) -, -O (CO) - or - (CO) O- groups interrupted C2 -C 2 O -alkylene, for example, 1-0xa-1, 3-propylene, 1, 4-dioxa-1, 6-hexylene, 1, 4,7-trioxa-1, 9-nonylene, 1-0xa-1, 4-butylene , 1, 5-dioxa-1, 8-octylene, 1-oxa-1, 5-pentylene, 1-oxa-1, 7-heptylene, 1, 6-dioxa-1, 10-decylene, 1-oxa-3 -methyl-1, 3-propylene, 1-oxa-3-methyl-1,4-butylene, 1-oxa-3,3-dimethyl-1, 4-butylene, 1-oxa-3,3-dimethyl-1 , 5-pentylene, 1,4-dioxa-3,6-dimethyl-1, 6-hexylene, 1-oxo-2-methyl-1,3-propylene, 1,4-dioxa-2,5-dimethyl-1 , 6-hexylene, 1-oxa-1, 5-pent-3-enylene, 1-oxa-1, 5-pent-3-ynylene, 1, 1, 1, 2, 1, 3 or 1, 4-cyclohexylene, 1, 2 or 1, 3-cyclopentylene, 1, 2, 1, 3 or 1, 4-phenylene, 4,4'-biph enylene, 1,4-diaza-1, 4-butylene, 1-aza-1, 3-propylene, 1, 4,7-triaza-1, 7-heptylene, 1, 4-diaza-1, 6-hexylene, 1, 4-diaza-7-oxa-1, 7-heptylene, 4,7-diaza-1-oxa-1, 7-heptylene, 4-aza-1-oxa-1, 6-hexylene, 1-aza- 4-oxa-1, 4-butylene, 1-aza-1, 3-propylene, 4-aza-1-oxa-1, 4-butylene, 4-aza-1, 7-dioxa-1, 7-heptylene, 4-aza-1-oxa-4-methyl-1,6-hexylene, 4-aza-1, 7-dioxa-4-methyl-1,7-heptylene, 4-aza-1-J-dioxa-4- ( 2'-hydroxyethyl) -1, 7-heptylene, 4-aza-1-oxa (2'-hydroxyethyl) -1, 6-hexylene or 1, 4-piperazinylene,

optionally substituted by aryl, alkyl, aryloxy, alkyloxy, heteroatoms and / or heterocycles C6-Ci2-arylene for example, 1, 2-, 1, 3- or 1, 4-phenylene, 4,4 '- biphenylene, tolylene or xylylene .

Ci-CI8-alkyl or optionally substituted by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups, C ₂ - C ₈ alkyl, for example, for example, methyl, ethyl, propyl, isopropyl, n-butyl, sec Butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, 2,4,4-trimethylpentyl, decyl, dodecyl, tetradecyl, heptadecyl, octadecyl, 1, 1-dimethylpropyl, 1, 1-dimethylbutyl, 1, 1,3,3-tetramethylbutyl, benzyl, 1-phenylethyl, 2-phenylethyl, α, α-dimethylbenzyl, benzhydryl, p-tolylmethyl, 1- (p-butylphenyl) -ethyl, p-chlorobenzyl, 2,4- Dichlorobenzyl, p-methoxybenzyl, m-ethoxybenzyl, 2-cyanoethyl, 2-cyanopropyl, 2-methoxycarbonethyl, 2-ethoxycarbonylethyl, 2-butoxycarbonylpropyl, 1, 2-di- (methoxy- carbonyl) -ethyl, 2-methoxyethyl, 2-ethoxyethyl, 2-butoxyethyl, diethoxymethyl, diethoxyethyl, 1, 3-dioxolan-2-yl, 1, 3-dioxan-2-yl, 2-methyl-1, 3 -dioxolan-2-yl, 4-methyl-1,3-dioxolan-2-yl, 2-isopropoxyethyl, 2-butoxypropyl, 2-octyloxyethyl, chloromethyl, 2-chloroethyl, trichloromethyl, trifluoromethyl, 1, 1-dimethyl-2 -chloroethyl, 2-methoxyisopropyl, 2-ethoxyethyl, butylthiomethyl, 2-dodecylthioethyl, 2-phenylthioethyl, 2,2,2-trifluoroethyl, 2-phenoxyethyl, 2-phenoxypropyl, 3-phenoxypropyl, 4-phenoxybutyl, 6-phenoxyhexyl , 2-methoxyethyl, 2-methoxypropyl, 3-methoxypropyl, 4-methoxybutyl, 6-methoxyhexyl, 2-ethoxyethyl, 2-ethoxypropyl, 3-ethoxypropyl, 4-ethoxybutyl or 6-ethoxyhexyl, and preferably methyl, ethyl, propyl, isopropyl , n-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl, 2-ethylhexyl, 2,4,4-trimethylpentyl, decyl, dodecyl, tetradecyl, heptadecyl, octadecyl, 1, 1-dimethylpropyl, 1, 1-dimethylbutyl, 1, 1,3,3-tetramethylbutyl, benzyl, 1-phenylethyl, 2-phenylethyl, α, α-dimethylbenzyl, benzyl, p-tolylmethyl, 1- (p-butylphenyl) ethyl, p-chlorobenzyl, 2,4-dichlorobenzyl, 2-cyanoethyl, 2-cyanopropyl, chloromethyl, 2-chloroethyl, trichloromethyl, Trifluoromethyl, 1, 1-dimethyl-2-chloroethyl and 2,2,2-trifluoroethyl,

optionally interrupted by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino C ₆ - Ci2-aryl example phenyl, ToIyI, XyIyI, α-naphthyl, ß-naphthyl, 4-diphenylyl, chlorophenyl, dichlorophenyl , Trichlorophenyl, difluorophenyl, methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, diethylphenyl, isopropylphenyl, tert-butylphenyl, dodecylphenyl, methoxyphenyl, dimethoxyphenyl, ethoxyphenyl, hexyloxyphenyl, methylnaphthyl, isopropylnaphthyl, chlomaphthyl, ethoxynaphthyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or 4-nitrophenyl, 2,4- or 2,6-dinitrophenyl, 4-dimethylaminophenyl, 4-acetylphenyl, Methoxyethylphenyl or ethoxymethylphenyl, and preferably phenyl, ToIyI, XyIyI, α-naphthyl, ß-naphthyl, 4-diphenylyl, chlorophenyl, dichlorophenyl, trichlorophenyl, difluorophenyl, methylphenyl, dimethylphenyl, trimethylphenyl, ethylphenyl, Die thylphenyl, isopropylphenyl, tert-butylphenyl, dodecylphenyl, chlomaphthyl, 2,6-dimethylphenyl, 2,4,6-trimethylphenyl, 2,6-dimethoxyphenyl, 2,6-dichlorophenyl, 4-bromophenyl, 2- or 4- Nitrophenyl, 2,4- or 2,6-dinitrophenyl,

C ₅ -C 12 -cycloalkyl, which is optionally interrupted by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups, for example cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, methylcyclopentyl, dimethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl, diethylcyclohexyl , Butylcyclohexyl, methoxycyclohexyl, dimethoxycyclohexyl, diethoxycyclohexyl, butylthiocyclohexyl, chlorocyclohexyl, dichlorocyclohexyl, dichlorocyclopentyl and a saturated or unsaturated bicyclic system such as norbornyl or norbornyl. bornenyl, and preferably cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, methylcyclopentyl, dimethylcyclopentyl, methylcyclohexyl, dimethylcyclohexyl, diethylcyclohexyl, butylcyclohexyl, chlorocyclohexyl, dichlorocyclohexyl, dichlorocyclopentyl and a saturated or unsaturated bicyclic system such as norbornyl or norbornenyl

and

optionally substituted by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino interrupted five- to six-membered, oxygen, nitrogen and / or sulfur atoms heterocycle having, for example, furyl, thiophenyl, pyrryl, pyridyl, indolyl, benzoxazolyl , Dioxolyl, dioxyl, benzimidazolyl, benzthiazolyl, dimethylpyridyl, methylquinolyl, dimethylpyrryl, methoxyfuryl, dimethoxypyridyl, difluoropyridyl, methylthiophenyl, isopropylthiophenyl or tert-butylthiophenyl.

Examples of R ² are a single bond, methylene, 1, 1-ethylene, 1, 2-ethylene, 1, 1-propylene, 1, 2-propylene, 1, 3-propylene, 1, 1-dimethyl-1, 2 ethylene, 1,4-butylene, 1,6-hexylene, 2-methyl-1,3-propylene, 2-ethyl-1,3-propylene, 2,2-dimethyl-1,3-propylene and 2,2- Dimethyl 1,4-butylene, 3-methyl-1,5-pentylene, 3,5-heptylene, 1,2-cyclopentylene, 1,3-cyclopentylene, 1,2-cyclohexylene, 1,3-cyclohexylene and ortho Phenylene is preferably a single bond, methylene, 1,1-ethylene, 1,2-ethylene, 1,1-propylene, 1,2-propylene, 1,3-propylene, 1,1-dimethyl-1,2-ethylene and 3,5-heptylene, particularly preferably a single bond, methylene, 1, 1-ethylene, 1, 2-ethylene, 1, 1-propylene, 1, 3-propylene and 3,5-heptylene, and most preferably 1 , 1-propylene and 3,5-heptylene.

Preferred examples of R ¹ and R ³ to R ¹⁰ are independently hydrogen, C 1 -C 4 -alkyl, n-hexyl, n-heptyl, n-octyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, n-eicosyl, 2-ethylhexyl, cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, phenyl, naphthyl or benzyl.

C 1 -C ₄ -alkyl in the context of this document denotes methyl, ethyl, isopropyl, n-propyl, n-butyl, isobutyl, sec-butyl or tert-butyl, preferably methyl, ethyl, n-propyl and n-propyl. Butyl, more preferably methyl, ethyl and n-butyl, and most preferably methyl and ethyl.

Preferred examples of diols (C) are 2-ethyl-1,3-hexanediol, 2-methyl-1,3-pentanediol, 2-propyl-1,3-heptanediol, 2,4-diethyloctan-1, 5-diol, 2,2-Dimethyl-1-phenyl-1,3-propanediol, 2-methyl-1,5-pentanediol, 3-methyl-2,6-heptanediol, 4-methylcyclohexane-1, 3 diol and 3,3-dimethyl-1,2-butaniol. Particularly preferred are 2-ethyl-1, 3-hexanediol, 2-methyl-1, 3-pentanediol and 2,4-diethyloctane-1, 5-diol, and most preferred are 2-ethyl-1, 3-hexanediol and 2 , 4-diethyloctane-1, 5-diol and especially 2,4-diethyloctane-1, 5-diol.

For the distinctness of the hydroxyl groups, it is necessary according to the invention for the hydroxyl groups to have a different environment, ie, for example, to have no conformation with mirror plane (σ), as is the case for example with 2-methyl-1,3-propanediol and / or no C2- Have axis of rotation, such as in 2,2-dimethyl-1, 3-propanediol.

In preferred diols (C), the two hydroxy groups are separated by not more than five carbon atoms, more preferably from three to five carbon atoms.

Other preferred diols (C) have not more than 12 carbon atoms.

In the process according to the invention, the esterification with (meth) acrylic acid or, preferably, the transesterification of the diol (C) with at least one, preferably a (meth) acrylate (D) in the presence of at least one, preferably exactly one catalyst (S).

Compounds (D) can be (meth) acrylic acid or esters of (meth) acrylic acid with a saturated alcohol, preferably saturated Ci - Cio-alkyl or C3 - C12 cycloalkyl esters of (meth) acrylic acid, more preferably saturated Ci - C ₄ - alkyl ester of (meth) acrylic acid.

Saturated in this document means compounds without C-C multiple bonds (except, of course, the C = C double bond in the (meth) acrylic moieties).

Examples of compounds (D) are (meth) acrylic acid methyl, ethyl, n-butyl, isobutyl, n-octyl and 2-ethylhexyl esters, 1,2-ethylene glycol di- and mono (meth ) acrylate, 1,4-butanediol and - mono (meth) acrylate, 1,6-hexanediol di- and - mono (meth) acrylate, trimethylolpropane tri (meth) acrylate and pentaerythritol tetra (meth) acrylate.

Particularly preferred are (meth) acrylic acid methyl, ethyl, n-butyl and 2-ethylhexyl esters and very particularly preferably (meth) acrylic acid methyl, ethyl and n-butyl ester. If the said alcohols are optically active, they are preferably used racemically or as mixtures of diastereomers, but it is also possible to use them as pure enantiomers or diastereomers or as enantiomer mixtures.

The inventive method is catalyzed by at least one catalyst (S), which in the case of a transesterification of the diol (C) with at least one (meth) acrylic acid ester (D) is selected from the group consisting of

(S1) inorganic salts, (S2) metal salts which have at least one cation selected from the group of alkaline earth metals, tin or titanium, preferably calcium, magnesium or tin,

- (S3) alkali metal salts of C 1 to C 6 alkoxides, preferably alkali metal salts of C 1 to C 4 alkoxides and more preferably potassium methoxide, and in the case of esterification of the diol (C) with (meth) acrylic acid is selected from - (S4) acids with a pKa value of 0 to 3, preferably phosphorous acid (H ₃ PO ₃ ), diphosphoric acid (H4P2O7), sulfonic acids, more preferably methanesulfonic acid, trifluoromethanesulfonic acid, para-toluenesulfonic acid, benzenesulfonic acid, dodecylbenzenesulfonic acid, cyclododecanesulfonic acid, camphorsulfonic acid or acid ion exchangers with sulfonic acid groups.

For polyprotic acids, the pKs value refers to the first hydrolysis step.

The acids (S4) may be organic or inorganic and solid or liquid acids.

Enzymes or decomposition products of enzymes do not belong to the catalysts, in particular not to the acidic catalysts in the sense of the present invention.

Inorganic salts (S1) which can be used according to the invention are preferably those which have a pKa of not more than 7.0, preferably not more than 6.1, and more preferably not more than 4.0. At the same time, the pKβ should not be less than 1.0, preferably not less than 1.5, and more preferably not less than 1.6.

Inorganic salts (S1) which can be used according to the invention are preferably heterogeneous inorganic salts. Heterogeneous catalysts are within the scope of this document those which have a solubility in the reaction medium at 25 ^° C. of not more than 1 g / l, preferably not more than 0.5 g / l and more preferably not more than 0.25 g / l.

The inorganic salt (S1) preferably has at least one anion selected from the group consisting of carbonate (CO ₃ ² ), bicarbonate (HCO ₃ ), phosphate (PO ₄ ³ ), hydrogen phosphate (HPO ₄ ² ), dihydrogen phosphate (H ₂ PO ₄ ), sulfate (SO ₄ ² ), sulfite (SO ₃ ² ) and carboxylate (R ⁶ -COO), wherein R ⁶ Ci - Ci ₈ alkyl or optionally by one or more oxygen and / or sulfur atoms and / or a or several substituted or unsubstituted imino groups interrupted C ₂ - Ci8-alkyl or Ce - Ci ₂ -aryl.

Preferred are carbonate and phosphate, particularly preferred is phosphate.

Phosphate is also to be understood as the condensation products, such as, for example, diphosphates, triphosphates and polyphosphates.

The inorganic salt (S1) preferably has at least one, more preferably exactly one cation selected from the group consisting of alkali metals, alkaline earth metals, ammonium, cerium, iron, manganese, chromium, molybdenum, cobalt, nickel or zinc.

Preference is given to alkali metals and particular preference to lithium, sodium or potassium.

Particularly preferred inorganic salts (S1) are Li ₃ PO ₄ , K ₃ PO ₄ , Na ₃ PO ₄ , K ₂ CO ₃ and Na ₂ CO ₃ and their hydrates, very particularly preferably K ₃ PO ₄ .

K ₃ PO ₄ can be used according to the invention in anhydrous form and as tri-, hepta- or nonahydrate.

The catalysed or transesterification catalyzed by the catalyst according to the invention is generally carried out at 50 to 140 ^° C., preferably at 50 to 100 ^° C., particularly preferably 50 to 90 ^° C., very particularly preferably 50 to 80 ^° C. and in particular 50 to 75 ° C.

Optionally, the reaction may be carried out under a slight vacuum of, for example, 300 hPa to atmospheric pressure, when released during the esterification Water or the resulting in the transesterification low-boiling alcohol, optionally as an azeotrope, to be distilled off.

The molar ratio in the transesterification between (meth) acrylic ester (D) and alcohol (C) in the case of the transesterification catalyzed by the catalyst is generally 2-7: 1 mol / mol, preferably 2-3.5: 1 mol / mol and particularly preferably 2.5-3.0: 1 mol / mol (based on the OH groups to be esterified).

The molar ratio in the esterification between (meth) acrylic acid and alcohol (C) in the esterification catalyzed by the catalyst is generally 1.0 to 4: 1 mol / mol, preferably 1.1 to 3.5: 1 mol / mol. mol and more preferably 1, 2 - 3.0: 1 mol / mol (based on esterifying OH groups).

The reaction time during the esterification or transesterification according to the invention is as a rule up to 8 hours, preferably up to 6 hours, more preferably less than 4 hours, very preferably up to 3 hours and in particular up to 2 hours.

The reaction time is generally at least 10 minutes, preferably at least 15 minutes, particularly preferably at least 30 minutes, very particularly preferably at least 45 minutes and in particular at least 60 minutes.

The content of catalyst (S) in the reaction medium is generally in the range of about 0.01 to 10 mol%, preferably 0.1 to 2.5, particularly preferably 0.2 to 2 mol%, and very particularly preferably 0.3 to 1, 5 mol% based on the sum of the components used (C).

In the case of esterification or transesterification, the presence of polymerization inhibitors (see above) is preferred according to the invention.

The presence of oxygen-containing gases (s.u.) during the reaction according to the invention is preferred.

In the catalysed or transesterification catalyzed according to the invention, the products having a color number below 500 APHA, preferably below 300, more preferably below 200, most preferably below 150, especially below 100, especially below 80 and even below 50 APHA (according to DIN ISO 6271 ) receive. The proportion of di (meth) acrylate in the sum of mono- and di (meth) acrylate of the diols (C) is less than 5% by weight, preferably less than 3, particularly preferably less than 2, in the case of the esterification or transesterification catalyzed according to the invention , very particularly preferably less than 1 and in particular less than 0.5% by weight.

This has the advantage that the resulting reaction mixtures are uniform and have only a small proportion of di (meth) acrylate, which would result in their use in polymerizations to undesirable crosslinking. Due to the low proportion of di (meth) acrylate, such unwanted crosslinking in polymerizations into which the products obtained according to the invention are used can be reduced or even suppressed.

The reaction can take place in organic solvents or mixtures thereof or without the addition of solvents. The batches are generally largely free of water (that is, below 10, preferably below 5, more preferably below 1, and most preferably below 0.5% by weight of water content). Furthermore, the approaches are largely free of primary and secondary alcohols, i. below 10, preferably below 5, more preferably below 1 and most preferably below 0.5% by weight alcohol content.

Suitable organic solvents are those known for this purpose, for example tertiary monools, such as C ₃ -C ₆ -alcohols, preferably tert-butanol, tert-amyl alcohol, pyridine, poly-Ci-C ₄ - alkylenglykoldi-Ci-C4-alkyl ether, preferred Polyethylene glycol di-C 1 -C 4 -alkyl ethers, for example 1, 2-dimethoxyethane, diethylene glycol dimethyl ether, polyethylene glycol dimethyl ether δOO, C 1 -C 4 -alkylene carbonates, in particular propylene carbonate, C 5 -C 6 -alkyl acetic acid esters, in particular tert-butylacetic acid esters, THF, toluene, 1, 3-dioxolane, acetone, isobutyl methyl ketone, ethyl methyl ketone, 1, 4-dioxane, tert-butyl methyl ether, cyclohexane, methylcyclohexane, toluene, hexane, dimethoxymethane, 1, 1-dimethoxyethane, acetonitrile, as well as their mono- or multiphase mixtures. Preference is given to those solvents which form an azeotrope together with separated water (water of reaction from the esterification) or together with split off alcohol (from the transesterification).

In one possible embodiment of the transesterification, the reaction is carried out in the (meth) acrylic ester used as the starting material. Very particular preference is given to carrying out the reaction in such a way that the product (F) is obtained after completion of the reaction as about 10 to 80 wt% solution in the (meth) acrylic acid ester used as starting material, in particular as 20 to 50 wt% Solution. The educts are either dissolved, suspended as solids or in emulsion in the reaction medium before. Preferably, the initial concentration of reactants is in the range of about 0.1 to 20 mol / l, more preferably 0.15 to 10 mol / l or 0.2 to 5 mol / l.

The reaction can be carried out continuously, for example in a tubular reactor or in a stirred reactor cascade, or discontinuously.

The reaction can be carried out in all reactors suitable for such a reaction. Such reactors are known to the person skilled in the art. The reaction preferably takes place in a stirred tank reactor or a fixed bed reactor.

For the mixing of the reaction mixture, any method can be used. Special stirring devices are not required. The mixing can be carried out, for example, by feeding in a gas, preferably an oxygen-containing gas (see below). The reaction medium can be monophase or polyphase and the reactants are dissolved, suspended or emulsified therein, optionally together with the molecular sieve and added to start the reaction, and optionally one or more times in the course of the reaction, with the catalyst (S). The temperature is adjusted to the desired value during the reaction and, if desired, can be increased or decreased during the course of the reaction.

If the reaction is carried out in a fixed bed reactor, the fixed bed reactor is preferably equipped with catalyst (S), the reaction mixture being pumped through a column filled with the catalyst (S). The reaction mixture can be pumped continuously through the column, with the flow rate, the residence time and thus the desired conversion is controllable. It is also possible to pump the reaction mixture through a column in the circulation, wherein the liberated alcohol can be distilled off simultaneously under vacuum.

The removal of water in the case of esterification or alcohols released by transesterification from the alkyl (meth) acrylates is carried out continuously or stepwise in a manner known per se, e.g. by vacuum, azeotropic removal, stripping, absorption, pervaporation and diffusion through membranes or extraction.

The stripping can be carried out, for example, by passing an oxygen-containing gas, preferably an air or air-nitrogen mixture, through the reaction mixture, optionally in addition to a distillation. For absorption are preferably molecular sieves or zeolites (pore size, for example in the range of about 3-10 Angstrom), a separation by distillation or with the aid of suitable semipermeable membranes.

But it is also possible, the separated mixture of alkyl (meth) acrylate and the underlying alcohol, which often forms an azeotrope, fed directly into a plant for the preparation of the alkyl (meth) acrylate, where it in an esterification with (meth ) to recycle acrylic acid.

After completion of the reaction, the resulting reaction mixture can be reused without further purification or, if necessary, purified in a further purification step.

purification step

As a rule, only the catalyst used is separated off from the reaction mixture and the reaction product is separated off from any organic solvent used.

A separation of heterogeneous catalyst is usually carried out by filtration, E lektrofiltration, absorption, centrifugation, sedimentation or decantation. The separated heterogeneous catalyst can then be used for further reactions or discarded.

The separation from the organic solvent is usually carried out by distillation, rectification or solid reaction products by filtration.

For further purification of the reaction product, a chromatography can also be carried out. However, such is usually not required and therefore less preferred.

However, in the purification step, only the catalyst and the optionally used solvent are preferably separated off.

The reaction conditions in the esterification or transesterification according to the invention are mild. Due to the low temperatures and other mild conditions, the formation of by-products in the reaction step is avoided. In the reaction of the invention, the (meth) acrylic compound (D) over the anyway addition usually stabilizer addition in at least the used (meth) acrylate or in the reaction mixture are added, for example, hydroquinone monomethyl ether, phenothiazine, phenols, such as 2-tert-butyl-4-methylphenol, 6-tert-butyl-2, 4-dimethyl-phenol or N-oxyls such as 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl or Uvinul® 4040P from BASF Aktiengesellschaft, for example in amounts of 50 to 2000 ppm.

The esterification or transesterification is preferably carried out in the presence of an oxygen-containing gas, preferably air or air-nitrogen mixtures. This oxygen-containing gas can be passed as a cover over the reaction mixture or preferably be bubbled through the reaction mixture.

Used heterogeneous catalysts (S1) can be easily removed from the final product, because the low solubility of the heterogeneous catalyst in the reaction medium remain at most negligible traces of the catalyst in the product. As a result, a simple filtration or decantation usually suffices for working up the reaction product.

If the process according to the invention is carried out with a non-heterogeneous catalyst, then at least one neutralization and / or washing may be expedient.

Thus, in the case of metal salts (S2) or alkanolates (S3) as a catalyst according to the invention usually a wash is sufficient, whereas when using the acids (S4) or in an esterification neutralization followed by a wash is useful.

For a wash, the reaction mixture in a washing apparatus with water or a 5-30% by weight, preferably 5 to 20, particularly preferably 5 to 15 wt% saline, potassium chloride, ammonium chloride, sodium sulfate or ammonium sulfate solution is preferred Saline, treated.

The quantitative ratio of reaction mixture: washing liquid is generally 1: 0.1-1, preferably 1: 0.2-0.8, particularly preferably 1: 0.3-0.7.

The laundry can be carried out, for example, in a stirred tank or in other conventional apparatus, for example in a column or mixer-settler apparatus. Technically, all known extraction and washing processes and apparatus can be used for a wash in the process according to the invention, for example those described in Ullmann's Encyclopedia of Industrial Chemistry, 6th ed, 1999 Electronic Release, Chapter: Liquid - Liquid Extraction - Apparatus are. For example, these may be one-stage or multistage, preferably single-stage extractions, as well as those in cocurrent or countercurrent mode, preferably countercurrent.

Preferably Siebboden- or packed or Füllkörperkolon- NEN, stirred tank or mixer-settler apparatus, and columns are used with rotating internals.

For neutralization, the organic phase, which may still contain small amounts of catalyst and the major amount of excess (meth) acrylic acid, with a 5-25, preferably 5 to 20, more preferably 5 to 15 wt% aqueous solution of a base , such as Sodium hydroxide solution, potassium hydroxide solution, sodium bicarbonate, sodium carbonate, potassium bicarbonate, calcium hydroxide, ammonia or KaIi- umcarbonat, which may optionally be added 5-15% by weight of sodium chloride, potassium chloride, ammonium chloride or ammonium sulfate, preferably with sodium hydroxide solution or sodium hydroxide solution, neutralized.

The addition of the base takes place in such a way that the temperature in the apparatus does not rise above 35 ⁰ C, preferably between 20 and 35 ⁰ C and the pH is 10-14. The removal of the heat of neutralization is preferably carried out by cooling the container by means of internal cooling coils or via a double wall cooling.

The quantitative ratio of reaction mixture: neutralizing liquid is generally 1: 0.1-1, preferably 1: 0.2-0.8, particularly preferably 1: 0.3-0.7.

With regard to the apparatus, what is said in the laundry applies.

Furthermore, the reaction under the reaction conditions according to the invention is very selective, it is generally less than 10%, preferably less than 5% by-products (based on the conversion).

By-products may be, for example, di (meth) acrylates, mono-esterification products of the higher-substituted hydroxy group with (meth) acrylic acid instead of the lower Ranger-substituted hydroxy group or Michael adducts of the hydroxy groups with (meth) acrylic acid.

Another object of the present invention are obtained from the diols (C) with different hydroxyl groups by the process according to the invention (meth) acrylates in which only the lower-substituted hydroxy groups are (meth) acrylated, but not the higher-substituted hydroxy groups.

These are preferably the compounds of the formula Ia

and formula IIa,

and formula IMa

wherein

R ¹ to R ^{10 are} as defined above and

R ^{11 is} hydrogen or methyl.

Particularly preferred are the following, esterified at the lower-substituted hydroxy group monoesters: (meth) acrylic acid 2-ethyl-3-hydroxy-hexyl ester, (Meth) acrylic acid 2-methyl-3-hydroxy-pentyl ester and (meth) acrylic acid 2,4-diethyl-1, 5-dihydroxy-octyl ester, most preferred are acrylic acid 2-ethyl-3-hydroxy-hexyl ester, acrylic acid 2-Methyl-3-hydroxy-pentyl ester and acrylic acid 2,4-diethyl-1,5-dihydroxy-octyl ester, in particular 2-ethyl-3-hydroxy-hexyl acrylate and 2,4-diethyl-1-acrylate , 5-dihydroxy-octyl ester and especially acrylic acid 2,4-diethyl-1, 5-dihydroxy-octyl ester.

The present invention further provides mixtures comprising at least one partially esterified (meth) acrylic ester (F) and at least one di (meth) acrylate of a diol (C) in which the weight ratio of partially esterified (meth) acrylic ester (F) to di ( meth) acrylate of a diol (C) is at least 99: 1 and preferably at least 99.5: 0.5.

The proportion of the di (meth) acrylate of the diol (C) in such mixtures is at least 0.01% by weight, preferably at least 0.05 and particularly preferably 0.1% by weight.

Preferably, such mixtures are obtained from the process according to the invention.

Such mixtures preferably have a color number below 500 APHA, preferably below 300, more preferably below 200, very preferably below 150, especially below 100, especially below 80 and even below 50 APHA (according to DIN ISO 6271).

Coatings containing partially esterified (meth) acrylic esters (F) thus obtained have very high scratch resistance, hardness, chemical resistance, elasticity and adhesion, both on hydrophilic and on hydrophobic substrates.

The preferably obtained partially esterified (meth) acrylic esters (F) obtainable according to the invention can advantageously be used as monomers or comonomers in poly (meth) acrylates or as reactive diluents in thermally, radiation and / or thermally curable poly (meth ) acrylates are used. Such poly (meth) acrylates are suitable, for example, as binders in thermal, radiation or dual-cure coating agents and in adhesives, for example acrylate adhesives, and in sealants. Furthermore, the partially esterified (meth) acrylic esters (F) can be used in polyurethanes, for example PU dispersions, PU foams, PU adhesives and PU coatings. By thermally curable is meant, for example, 1-component and 2-component coating systems, which are additionally reacted with crosslinking reagents, for example melamine resins or isocyanate derivatives. A further subject of the present application is therefore the use of the partially esterified (meth) acrylic esters prepared by the process according to the invention as reactive diluents or binders in blasting or dual-cure coating compositions, preferably in top coats, particularly preferably in transparent clear coats. Of course, the partially esterified (meth) acrylic esters prepared according to the invention can also be used as monomers in polymerizations, optionally together with other polymerizable monomers, such as (meth) acrylic acid, (meth) acrylic acid ester, styrene, butadiene, acrylonitrile, vinyl acetate, N-vinylpyrrolidone, 4 Hydroxybutyl vinyl ether or N-vinylformamide.

By "dual-cure" is meant that the coating compositions are curable thermally and with actinic radiation. In the context of the present invention, actinic radiation means electromagnetic radiation such as visible light, UV radiation or X-radiation, in particular UV radiation, and corpuscular radiation such as electron radiation.

Radiation-curable binders are those which are curable by means of actinic radiation as defined above, in particular by means of UV radiation.

A further subject of the present application are coating formulations comprising the partially esterified (meth) acrylic acid esters obtainable by the process according to the invention and preferably obtained. The partially esterified (meth) acrylic acid esters can be used both in basecoats and in topcoats. Because of their particular properties, such as increasing the scratch resistance and elasticity, as well as the lowering of the viscosity, especially in branched polyacrylates, a radiation-cured clearcoat, their use in topcoats is preferred.

In addition to the preferably obtained partially esterified (meth) acrylic esters (F) obtainable by the process according to the invention, a radiation-curable composition of the invention may also contain the following components:

(G) at least one polymerizable compound having a plurality of copolymerizable, ethylenically unsaturated groups,

(H) optionally reactive diluents,

(I) optionally photoinitiator as well (J) optionally further paint-typical additives.

Suitable compounds (G) are radiation-curable, free-radically polymerizable compounds having a plurality of, i. E. at least two copolymerizable, ethylenically unsaturated groups into consideration.

It is preferable that compounds (G) are vinyl ether or (meth) acrylate compounds, more preferably each of the acrylate compounds, i. the derivatives of acrylic acid.

Preferred vinyl ether and (meth) acrylate compounds (G) contain 2 to 20, preferably 2 to 10 and very particularly preferably 2 to 6 copolymerizable, ethylenically unsaturated double bonds.

Particular preference is given to those compounds (G) having an ethylenically unsaturated double bond content of 0.1-0.7 mol / 100 g, very particularly preferably 0.2-0.6 mol / 100 g.

The number average molecular weight M _{n of} the compounds (G) is, unless stated otherwise, preferably below 15,000, particularly preferably 300-12,000, very particularly preferably 400-5000 and in particular 500-3000 g / mol (determined by gel permeation chromatography with polystyrene as standard and tetrahydrofuran as eluent).

As (meth) acrylate compounds may be mentioned (meth) acrylic acid esters and in particular acrylic acid esters and vinyl ethers of polyfunctional alcohols, in particular those which contain no further functional groups or at most ether groups in addition to the hydroxyl groups. Examples of such alcohols are e.g. bifunctional alcohols such as ethylene glycol, propylene glycol and their more highly condensed species, e.g. such as diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, etc., 1, 2-, 1, 3- or 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 3-methyl-1, 5-pentanediol, neopentyl glycol , alkoxylated phenolic compounds, such as ethoxylated or propoxylated bisphenols, 1, 2-, 1, 3- or 1, 4-cyclohexanedimethanol, trifunctional and higher functional alcohols, such as glycerol, trimethylolpropane, butanetriol,

Trimethylolethane, pentaerythritol, ditrimethylolpropane, dipentaerythritol, sorbitol, mannitol and the corresponding alkoxylated, in particular ethoxylated and / or propoxylated alcohols. The alkoxylation products are obtainable in a known manner by reacting the above alcohols with alkylene oxides, in particular ethylene oxide or propylene oxide. The degree of alkoxylation per hydroxyl group is preferably 0 to 10, ie 1 mol of hydroxyl group can be alkoxylated with up to 10 mol of alkylene oxides.

Other suitable (meth) acrylate compounds are polyester (meth) acrylates, which are the (meth) acrylic esters or vinyl ethers of polyesterols, and urethane, epoxide or melamine (meth) acrylates.

Urethane (meth) acrylates are e.g. obtainable by reacting polyisocyanates with hydroxyalkyl (meth) acrylates and optionally chain extenders such as diols, polyols, diamines, polyamines or dithiols or polythiols.

The urethane (meth) acrylates preferably have a number average molecular weight M _{n of} from 500 to 20,000, in particular from 750 to 10,000, more preferably from 750 to

3000 g / mol (determined by gel permeation chromatography with polystyrene as standard).

The urethane (meth) acrylates preferably have a content of 1 to 5, particularly preferably 2 to 4 moles of (meth) acrylic groups per 1000 g of urethane (meth) acrylate.

Epoxy (meth) acrylates are obtainable by reacting epoxides with (meth) acrylic acid. Suitable epoxides are, for example, epoxidized olefins or glycidyl ethers, e.g. Bisphenol-diglycidyl ethers or aliphatic glycidyl ethers, such as butanediol diglycidyl ether.

Melamine (meth) acrylates are obtainable by reacting melamine with (meth) acrylic acid or its esters.

The epoxide (meth) acrylates and melamine (meth) acrylates preferably have a number average molecular weight M _{n of} from 500 to 20,000, more preferably from 750 to 10,000 g / mol, and most preferably from 750 to 3,000 g / mol; the content of (meth) acrylic groups is preferably 1 to 5, more preferably 2 to 4 per 1000 g of epoxy (meth) acrylate or melamine (meth) acrylate (determined by gel permeation chromatography with polystyrene as standard and tetrahydrofuran as eluent). Also suitable are carbonate (meth) acrylates which contain on average preferably 1 to 5, in particular 2 to 4, particularly preferably 2 to 3 (meth) acrylic groups and very particularly preferably 2 (meth) acrylic groups.

The number average molecular weight M _{n of} the carbonate (meth) acrylates is preferably less than 3000 g / mol, more preferably less than 1500 g / mol, particularly preferably less than 800 g / mol (determined by gel permeation chromatography with polystyrene as standard, solvent tetrahydrofuran).

The carbonate (meth) acrylates are readily obtainable by transesterification of carbonic acid esters with polyhydric, preferably dihydric alcohols (diols, eg hexanediol) and subsequent esterification of the free OH groups with (meth) acrylic acid or transesterification with (meth) acrylic esters, such as it eg in EP-A 92,269. They are also available by reacting phosgene, urea derivatives with polyvalent, e.g. dihydric alcohols.

Suitable reactive diluents (compounds (H)) are radiation-curable, free-radically or cationically polymerizable compounds having only one ethylenically unsaturated, copolymerizable group.

Called e.g. C 1 -C 20 -alkyl (meth) acrylates, vinylaromatics having up to 20 carbon atoms, vinyl esters of carboxylic acids containing up to 20 carbon atoms, ethylenically unsaturated nitriles, vinyl ethers of alcohols containing from 1 to 10 carbon atoms, α, β-unsaturated Carboxylic acids and their anhydrides and aliphatic hydrocarbons having 2 to 8 C atoms and 1 or 2 double bonds.

Preferred (meth) acrylic acid alkyl esters are those having a C 1 -C 10 -alkyl radical, such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate.

In particular, mixtures of (meth) acrylic acid alkyl esters are also suitable.

Vinyl esters of carboxylic acids having 1 to 20 carbon atoms are e.g. Vinyl laurate, vinyl stearate, vinyl propionate and vinyl acetate.

α.beta.-Unsaturated carboxylic acids and their anhydrides can be, for example, acrylic acid, methacrylic acid, fumaric acid, crotonic acid, itaconic acid, maleic acid or maleic anhydride, preferably acrylic acid. Suitable vinylaromatic compounds are, for example, vinyltoluene, α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene.

Examples of nitriles are acrylonitrile and methacrylonitrile.

Suitable vinyl ethers are e.g. Vinyl methyl ether, vinyl isobutyl ether, vinyl hexyl ether and vinyl octyl ether.

Non-aromatic hydrocarbons having 2 to 8 C atoms and one or two olefinic double bonds may be mentioned butadiene, isoprene, and also ethylene, propylene and isobutylene.

Furthermore, N-vinylformamide, N-vinylpyrrolidone and N-vinylcaprolactam can be used.

As photoinitiators (I), photoinitiators known to those skilled in the art can be used, e.g. those in "Advances in Polymer Science", Volume 14, Springer Berlin 1974 or in K.K. Dietliker, Chemistry and Technology of UV and EB Formulation for Coatings, Inks and Paints, Volume 3; Photoinitiators for Free Radical and Cationic Polymerization, P.K.T. Oldring (Eds), SITA Technology Ltd, London.

Suitable examples are mono- or Bisacylphosphinoxide Irgacure 819 (bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide), as described for example in EP-A 7 508, EP-A 57 474, DE-A 196 18 720, EP-A for example, 2,4,6-trimethylbenzoyldiphenylphosphine oxide (Lucirin ^® TPO), ethyl-2,4,6-trimethylbenzoylphenylphosphinate, benzophenones, hydroxyacetophenones, Phenylgly- described 495751 or EP-A 615 980, oxylic acid and its derivatives or mixtures of these photoinitiators. Examples which may be mentioned are benzophenone, acetophenone, acetonaphthoquinone, methyl ethyl ketone, vaIerophenone, hexanophenone, α-phenylbutyrophenone, p-morpholinopropiophenone, dibenzosuberone, 4-morpholinobenzophenone, 4-morpholinodeoxybenzoin, p-diacetylbenzene, 4-aminobenzophenone, 4'-methoxyacetophenone , β-methylanthraquinone, tert-butylanthraquinone, anthraquinone-carboxylic acid ester, benzaldehyde, α-tetralone, 9-acetylphenanthrene, 2-acetylphenanthrene, 10-thioxanthenone, 3-acetylphenanthrene, 3-acetylindole, 9-fluorenone, 1-indanone, 1, 3,4 Tri-acetylbenzene, thioxanthen-9-one, xanthene-9-one, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropyltrioxanthone, 2,4-dichlorothioxanthone, benzoin, benzoin isobutyl ether, chloroxanthenone, benzoin tetrahydropyranyl ether, benzoin methyl ether, benzoin ethyl ether, benzoin butyl ether, benzoin isopropyl ether, 7-H-benzoin methyl ether, benz [de] anthracen-7-one, 1-naphthaldehyde , 4,4 ^1-bis (dimethylamino) benzophenone, 4-phenylbenzophenone, 4- Chlorobenzophenone, Michler's ketone, 1-acetonaphthone, 2-acetonaphthone, 1-benzoylcyclohexan-1-ol, 2-hydroxy-2,2-dimethylacetophenone, 2,2-dimethoxy-2-phenylaceto-tophenone, 2,2-diethoxy 2-phenylacetophenone, 1, 1-dichloroacetophenone, 1-hydroxyace- tophenone, acetophenone dimethyl ketal, o-methoxybenzophenone, triphenylphosphine, tri-o-tolylphosphine, benz [a] anthracene-7,12-dione, 2,2-diethoxyacetophenone, benzil ketals such as benzil dimethyl ketal, 2-methyl-1 - [4- (methylthio) phenyl] -2-morpholinopropan-1-one, anthraquinones such as 2-methylanthraquinone, 2-ethylanthraquinone, 2-tert-butylanthraquinone, 1-chloroanthraquinone, 2 -Amylanthraquinone and 2,3-butanedione.

Also suitable are non-yellowing or slightly yellowing photoinitiators of the phenylglyoxalic acid ester type, as described in DE-A 198 26 712, DE-A 199 13 353 or WO 98/33761.

Among the photoinitiators mentioned, phosphine oxides, α-hydroxyketones and benzophenones are preferred.

In particular, mixtures of different photoinitiators can be used.

The photoinitiators may be used alone or in combination with a photopolymerization onspromotor, e.g. benzoic, amine or similar type.

Examples of further typical coatings (J) are antioxidants, oxidation inhibitors, stabilizers, activators (accelerators), fillers, pigments, dyes, degassing agents, brighteners, antistatic agents, flame retardants, thickeners, thixotropic agents, leveling agents, binders, antifoams, Perfumes, surface active agents, viscosity modifiers, plasticizers, plasticizers, tackifiers, chelating agents or compatibilizers.

As a post-curing accelerator, e.g. Tin octoate, zinc octoate, dibutyltin laureate or diaza [2.2.2] bicyclooctane.

It is also possible to add one or more photochemically and / or thermally activatable initiators, for example potassium peroxodisulfate, dibenzoyl peroxide, cyclohexanone peroxide, di-tert-butyl peroxide, azobisisobutyronitrile, cyclohexylsulfonyl acetyl peroxide, diisopropyl percarbonate, tert-butyl peroctoate or benzpinacol, for example, those thermally activable initiators which have a half-life at 80 ⁰ C of more than 100 hours, such as di-t-butyl peroxide, cumene hydroperoxide, dicumyl peroxide, t-butyl perbenzoate, silylated pinacols, the z. B. commercially available under the trade name ADDID 600 from Wacker or hydroxyl-containing amine-N-oxides, such as 2,2,6,6-tetramethylpiperidine-N-oxyl, 4-hydroxy-2,2,6, 6-tetramethylpiperidine-N-oxyl etc.

Further examples of suitable initiators are described in "Polymer Handbook" 2nd ed., Wiley & Sons, New York.

Suitable thickeners besides free-radically (co) polymerized (co) polymers, customary organic and inorganic thickeners such as hydroxymethylcellulose or bentonites are also suitable.

As chelating agents, e.g. Ethylenediamine and their salts and ß-diketones are used.

Suitable fillers include silicates, e.g. Example by hydrolysis of silicon tetrachloride available silicates such as Aerosil ^® the Fa. Degussa, silica, talc, aluminum silicates, magnesium silicates, calcium carbonates, etc.

Suitable stabilizers include typical UV absorbers such as oxanilides, triazines and benzotriazole (the latter available as Tinuvin ^® grades from Ciba-Spezialitatenchemie) and benzophenones. These may be used alone or together with suitable radical scavengers, for example sterically hindered amines such as 2,2,6,6-tetramethylpiperidine, 2,6-di-tert-butylpiperidine or derivatives thereof, eg. B. bis (2,2,6,6-tetra-methyl-4-piperidyl) sebacinate used. Stabilizers are usually used in amounts of 0.1 to 5.0 wt .-%, based on the solid components contained in the preparation.

Further suitable stabilizers are, for example, N-oxyls, for example 4-hydroxy-2,2,6,6-tetramethylpiperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethylpiperidine-N-oxyl , 4-acetoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 2,2,6,6-tetramethyl-piperidine-N-oxyl, 4.4 ^1, 4, ^11-tris (2,2 , 6,6-tetramethyl-piperidine-N-oxyl) phosphite or 3-0x0-2,2,5,5-tetramethylpyrrolidine-N-oxyl, phenols and naphthols, such as p-aminophenol, p-nitrosophenol, 2-tert-butylphenol, 4-tert-butylphenol, 2,4-di-tert-butylphenol, 2-methyl-4-tert-butylphenol, 4-methyl-2,6-tert-butylphenol (2 , 6-tert-butyl-p-cresol) or 4-tert-butyl-2,6-dimethylphenol, quinones, such as hydroquinone or hydroquinone monomethyl ether, aromatic amines, such as N, N-diphenylamine, N-nitroso - diphenylamine, phenylenediamines, such as N.N'-dialkyl-para-phenylenediamine, where the alkyl radicals may be the same or different and each independently consist of 1 to 4 carbon atoms and may be straight-chain or branched, hydroxylamines such as N, N-diethylhydroxylamine, urea derivatives such as urea or thiourea, phosphorus-containing compounds such as triphenylphosphine, tri- phenylphosphite or triethyl phosphite or sulfur-containing compounds such Diphenyl sulfide or phenothiazine.

Preferred stabilizers are hydroquinone monomethyl ether and phenothiazine, particularly preferred is hydroquinone monomethyl ether.

Typical compositions for radiation-curable compositions are, for example

(F) 20-100% by weight, preferably 40-90, particularly preferably 50-90 and in particular 60-80% by weight,

(G) 0 to 60% by weight, preferably 5 to 50, particularly preferably 10 to 40 and in particular 10 to 30% by weight,

(H) 0 to 50% by weight, preferably 5 to 40, particularly preferably 6 to 30 and in particular 10 to 30% by weight,

(I) 0-20% by weight, preferably 0.5-15, particularly preferably 1-10 and especially 2-5% by weight and (J) 0-50% by weight, preferably 2-40, particularly preferably 3-30 and in particular 5-20% by weight,

with the proviso that (F), (G), (H), (I) and (J) together add up to 100% by weight.

The substrates are coated by customary methods known to the person skilled in the art, at least one coating composition being applied to the substrate to be coated in the desired thickness and the volatile constituents of the coating composition, if appropriate with heating, being removed. If desired, this process can be repeated one or more times. The application to the substrate can in a known manner, for. B. by spraying,

Filling, doctoring, brushing, rolling, rolling, pouring, lamination, injection molding or coextrusion done. The coating thickness is generally in a range of about 3 to 1000 g / m ² and preferably 10 to 200 g / m ² .

In addition, a process for coating substrates is disclosed in which the coating composition is applied to the substrate and optionally dried, cured with electron beams or UV exposure under an oxygen-containing atmosphere or preferably under inert gas, optionally at temperatures up to the level of Drying temperature and then at temperatures up to 160 ⁰ C, preferably between 60 and 160 ⁰ C, thermally treated.

The method for coating substrates can also be carried out so that after application of the coating composition initially at temperatures up to 160 ⁰ C, preferably between 60 and 160 ⁰ C, thermally treated and then with electron beams or UV exposure under oxygen or preferably under inert gas is hardened.

If desired, the curing of the films formed on the substrate can be effected exclusively thermally. In general, however, the coatings are cured both by irradiation with high-energy radiation and thermally.

The curing can also be carried out in addition to or instead of the thermal curing by NIR radiation, wherein NIR radiation here electromagnetic radiation in the wavelength range of 760 nm to 2.5 microns, preferably from 900 to 1500 nm is designated.

Optionally, if a plurality of layers of the coating composition are applied one above the other, thermal, NIR and / or radiation curing can take place after each coating operation.

Suitable radiation sources for radiation curing are, for example, low-pressure mercury lamps, medium-pressure lamps with high-pressure lamps and fluorescent tubes, pulse emitters, metal halide lamps, electronic flash devices, whereby radiation curing without photoinitiator is possible, or excimer radiators. The radiation curing is effected by the action of high-energy radiation, ie UV radiation or daylight, preferably emits light in the wavelength range of λ = 200 to 700 nm, particularly preferably λ = 200 to 500 nm and very particularly preferably λ = 250 to 400 nm, or by irradiation with high-energy electrons (electron radiation, 150 to 300 keV). The radiation sources used are, for example, high-pressure mercury vapor lamps, lasers, pulsed lamps (flash light), halogen lamps or excimer radiators. The radiation dose for UV curing, which is usually sufficient for crosslinking, is in the range from 80 to 3000 mJ / cm ² .

Of course, several radiation sources can be used for the curing, e.g. two to four.

These can also radiate in different wavelength ranges. The irradiation may optionally also in the absence of oxygen, for. B. under inert gas atmosphere, are performed. As inert gases are preferably nitrogen, noble gases, carbon dioxide, or combustion gases. Furthermore, the irradiation can be carried out by covering the coating composition with transparent media. Transparent media are z. As plastic films, glass or liquids, eg. B. water. Particular preference is given to irradiation in the manner described in DE-A1 199 57 900.

Another object of the invention is a method for coating substrates, wherein

i) coating a substrate with a coating composition as described above,

ii) removing volatile constituents of the coating composition for film formation under conditions in which the photoinitiator (I) still substantially does not form free radicals,

iii) optionally irradiating the film formed in step ii) with high energy radiation, wherein the film is precured, then optionally mechanically working the precured film coated article or contacting the surface of the precured film with another substrate,

iv) the film cures thermally or with NIR radiation

In this case, the steps iv) and iii) can also be performed in reverse order, d. H. The film may first be cured thermally or by NIR radiation and then with high energy radiation.

Furthermore, the substrate coated with a multilayer coating according to the invention is also the subject of the present invention.

The thickness of such a layer to be cured as described may be from 0.1 μm to several mm, preferably from 1 to 2000 μm, more preferably from 5 to 1000 μm, most preferably from 10 to 500 μm and especially from 10 to 250 μm. The partially esterified (meth) acrylic esters prepared according to the invention can advantageously also be used in a thermally induced (free-radical) (co) polymerization because of their lower color.

As monomers with which the partially esterified according to the invention

For example, (meth) acrylic acid esters may be copolymerized, e.g. C 1 -C 20 -alkyl (meth) acrylates, vinylaromatics having up to 20 carbon atoms, vinyl esters of carboxylic acids containing up to 20 carbon atoms, ethylenically unsaturated nitriles, vinyl ethers of alcohols containing from 1 to 10 carbon atoms and aliphatic hydrocarbons with 2 to 8 C atoms and 1 or 2 double bonds.

Preferred (meth) acrylic acid alkyl esters are those having a C 1 -C 10 -alkyl radical, such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and branched alkyl derivatives, such as 2-ethylhexyl acrylate.

In particular, mixtures of (meth) acrylic acid alkyl esters are also suitable.

As vinyl aromatic compounds are e.g. Vinyltoluene, α-butylstyrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene into consideration.

Examples of nitriles are acrylonitrile and methacrylonitrile.

A common but not the only method for preparing such (co) polymers is free-radical or ionic (co) polymerization in a solvent or diluent.

The free-radical (co) polymerization of such monomers takes place, for example, in aqueous solution in the presence of polymerization initiators which decompose into free radicals under polymerization conditions, for example peroxodisulfates, HΣOΣ redox systems or hydroxy peroxides, such as tert. Butyl hydroperoxide or cumene hydroperoxide. The (co) polymerization can be carried out in a wide temperature range, optionally under reduced or under elevated pressure usually at temperatures up to 100 ⁰ C. The pH of the reaction mixture is usually adjusted in the range of 4 to 10.

However, the (co) polymerization can also be carried out continuously or batchwise in another manner known per se to those skilled in the art, e.g. as a solution, precipitate, water-in-oil emulsion, inverse emulsion, suspension or reverse suspension polymerization.

In this case, the monomer (s) is / are prepared using radical polymerization initiators, for example radical-decomposing azo compounds, such as 2,2'-azobis (isobutyronitrile), 2,2'-azobis (2-amidinopropane) hydrochloride or 4, 4'-azobis (4 ¹ -cyanopentanoic acid) or dialkyl peroxides, such as di-tert-amyl peroxide, aryl-alkyl peroxides, such as tert-butyl-cumyl peroxide, alkyl-acyl peroxides, such as tert-butyl peroxy 2-ethylhexanoate, peroxydicarbonates, such as di- (4-tert-butylcyclohexyl) peroxydicarbonate or hydroperoxides (co) polymerized.

The compounds mentioned are usually employed in the form of aqueous solutions or aqueous emulsions, the lower concentration being determined by the amount of water which is acceptable in the (co) polymerization and the upper concentration by the solubility of the relevant compound in water.

As a solvent or diluent, e.g. Water, alcohols, such as methanol, ethanol, n- or iso-propanol, n- or iso-butanol, or ketones, such as acetone, ethyl methyl ketone, diethyl ketone or isobutyl methyl ketone. Particular preference is given to nonpolar solvents such as, for example, xylene and its mixtures of isomers, Shellsol® A and solvent naphtha.

In a preferred embodiment, the monomers are premixed and initiator added with any further additives dissolved in solvent. A particularly preferred embodiment is described in WO 01/23484 and there particularly on page 10, Z. 3 to Z. 24.

Optionally, the (co) polymerization in the presence of polymerization regulators, such as hydroxylammonium salts, chlorinated hydrocarbons and thio compounds, such as tert-butylmercaptan, thioglycolic acid ethylacrylic ester, mercaptoethynol, mercaptopropyltrimethoxysilane, dodecylmercaptan, tert.- Dodecylmercaptan or alkali metal hypophosphites. In (co) polymerization, these regulators, for. B. in amounts of 0 to 0.8 parts by weight, based on 100 parts by weight of the (co) polymerizing monomers are used by the molecular weight of the resulting (co) polymer is reduced.

In the emulsion polymerization, dispersants, ionic and / or nonionic emulsifiers and / or protective colloids or stabilizers can be used as surface-active compounds.

As such, both the protective colloids customarily used for carrying out emulsion polymerizations and emulsifiers are suitable.

Suitable protective colloids are, for example, polyvinyl alcohols, cellulose derivatives or vinylpyrrolidone-containing copolymers. A detailed description of other suitable protective colloids can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, macromolecular substances, Georg-Thieme-Verlag, Stuttgart, 1969, pp. 411 to 420. Of course, mixtures of emulsifiers and / or or protective colloids. The dispersants used are preferably exclusively emulsifiers whose relative molecular weights, in contrast to the protective colloids, are usually below 1000. They may be anionic, cationic or nonionic in nature. Of course, in the case of the use of mixtures of granzflächenaktiv substances, the individual components must be compatible with each other, which can be checked in case of doubt by hand on fewer preliminary tests. In general, anionic emulsifiers are compatible with each other and with nonionic emulsifiers.

The same applies to cationic emulsifiers, while anionic and cationic emulsifiers are usually incompatible with each other. Customary emulsifiers are, for example, ethoxylated mono-, di- and tri-alkylphenols (EO units: 3 to 100: C ₄ to C _2), ethoxylated fatty alcohols (EO units: 3 to 100, alkyl radical: C ₈ to Ci ₈₎ , and alkali metal and ammonium salts of alkylsulfates (alkyl radical: C ₈ to Ci6) ethoxylated sulfuric acid monoesters of alkylphenols (EO units: 3 to 100, alkyl radical: _C4 to C12), of alkyl sulfonic acids (alkyl radical: C12 to C ₈₎ and of alkylacrylic sulfonic acids (alkyl radical: C ₉ to Cis). Further suitable emulsifiers, such as sulfosuccinic acid esters, can be found in Houben-Weyl, Methods of Organic Chemistry, Volume XIV / 1, Macromolecular Materials, Georg-Thieme Verlag, Stuttgart, 1961, pages 192 to 208.

In general, the amount of dispersant used is 0.5 to 6, preferably 1 to 3 wt .-% based on the monomers to be radically polymerized. Examples of (meth) acrylate-containing dispersions are n-butyl acrylate / acrylonitrile dispersions which are used as adhesives, n-butyl acrylate / butadiene / styrene

The polymer dispersions in which partially esterified (meth) acrylic esters prepared according to the invention are used can additionally be deodorized chemically and / or physically.

The copolymers obtainable with the partially esterified (meth) acrylic esters prepared according to the invention generally also have a lower color number due to the lower color number of the (meth) acrylic esters prepared according to the invention (which is advantageous in the paint sector). The copolymers described can then be prepared in a manner known per se, for example with aminoplasts, e.g. Melamine, to crosslinked coating resins implement, as described for example in EP 738740 or EP 675141.

The coating compositions according to the invention are particularly preferably suitable as or in exterior coatings, ie those applications that are exposed to daylight, preferably of buildings or building parts, interior coatings, road markings, coatings on vehicles and aircraft. In particular, the coatings are used as wood, paper or plastic coatings, for example for parquet or furniture.

With the aid of the process according to the invention, it is possible to produce partially esterified (meth) acrylic esters (F) in high chemical and space-time yield and under mild conditions with good color numbers. Despite the absence of protective groups and activated (meth) acrylic acid compounds, the desired partially esterified products are obtained in a targeted manner with high selectivity, which are free from by-products.

If a plurality of lower-substituted hydroxy groups are present, generally all lower-substituted hydroxy groups are uniformly substituted with a sufficient amount of (meth) acrylating reagent before higher-substituted hydroxy groups are (meth) acrylated.

The selectivity of the reaction according to the invention with respect to the (meth) acrylation of the lower-substituted hydroxy groups compared to the lower-substituted hydroxy groups is generally at least 90:10, preferably at least 95: 5, more preferably at least 97: 3, most preferably at least 98: 2 and in particular at least 99: 1. The following examples are intended to illustrate the characteristics of the invention without, however, limiting it.

Examples

As "parts" are in this document, unless otherwise stated, "parts by weight" understood.

Comparative example

The protocol of KL Shantha, G. Pratap, VS Bhaskar Rao, and N. Krishnamurti of Journal of Applied Polymer Science, 1990, 41, 945-954 was applied to the esterification of 2,4-diethyloctane-1, 5-diol :

For this purpose, 20.2 g (0.1 mol) of 2,4-diethyloctane-1, 5-diol in 200 ml of benzol initially charged at room temperature and 7.92 g (0.11 mol) of acrylic acid, 0.5 g of hydroquinone and Added 0.5 g (0.0026 mol) of para-toluenesulfonic acid.

The mixture was stirred for 4 hours at boiling temperature while circling 1, 4 ml of water through a water separator. It was then cooled to room temperature.

0.21 g of sodium acetate were added, the solvent was removed under reduced pressure and to the residue 150 ml of methyl tert-butyl ether was added and the organic phase was washed twice with 70 ml of water each time.

Then 1 spatula tip of activated charcoal was added, the batch was filtered and the solvent removed in vacuo.

This gave 21.1 g of a yellow liquid having a color number of 5 Gardner (538 APHA). According to ¹ H-NMR, the proportion of diacrylate and monoacrylate at the secondary hydroxy group in total relative to the desired monoacrylate at the primary hydroxy group was at least 1:10.

Claims

claims

1. A process for the preparation of partially esterified (meth) acrylic acid esters (F) with a

Color number according to DIN ISO 6271 below 500 APHA and a proportion of di (meth) acrylate in the sum of mono- and di (meth) acrylate of the diols (C) of less than 5% by weight of divalent aliphatic diols (C), containing different hydroxy groups, characterized in that one

either

(1) at least one diol (Ci) having a primary hydroxy group and a secondary hydroxy group,

or

(2) at least one diol (C2) having a primary hydroxy group and a tertiary hydroxy group,

or

(3) at least one diol (C3) having a secondary hydroxy group and a tertiary hydroxy group,

where in (1) to (3) in each case the higher-substituted hydroxy group in position β bears at least one alkyl, cycloalkyl, aryl or aralkyl radical,

or

(4) at least one diol (C ₄ ) having two primary hydroxyl groups, one of which carries at least one in position β and no alkyl, cycloalkyl, aryl or aralkyl radical in position β,

or

(5) at least one diol (C5) having two secondary hydroxy groups, one of which in position β has at least one and one in position β no alkyl,

Bears cycloalkyl, aryl or aralkyl radical,

in the presence of at least one catalyst (S) esterified with (meth) acrylic acid or transesterified in the presence of at least one catalyst (S) with at least one (meth) acrylic acid ester (D), wherein the catalyst (S) in the case of a transesterification of the diol ( C) having at least one (meth) acrylic acid ester (D) is selected from the group consisting of (51) inorganic salts,

(52) metal salts having at least one cation selected from the group consisting of alkaline earth metals, tin and titanium,

(53) alkali metal salts of C 1 to C 6 alkoxides,

and in the case of esterification of the diol (C) with (meth) acrylic acid is selected from

(54) acids with a pKa of 0 to 3.

Process according to Claim 1, characterized in that the diol (C) is one of the formula I

or formula II

or formula II

wherein

R ¹ and R ³ to R ^{10 are} each independently hydrogen, Ci - Ci8-alkyl, optionally by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups interrupted C ₂ - Ciβ-alkyl, C ₆ - Ci ₂ -aryl, C ₅ - Ci ₂ -cycloalkyl or a five- to six-membered, oxygen, nitrogen and / or sulfur atoms Heterocycle, wherein said radicals may each be substituted by aryl, alkyl, aryloxy, alkyloxy, heteroatoms and / or heterocycles, and

R ^{2 is} a single bond, C 1 -C ₂₀ -alkylene, C ₅ -C ₂ -cycloalkylene, C ₆ -C ₂ -arylene or by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups and or one or more cycloalkyl, - (CO) -, -O (CO) O-, - (NH) (CO) O-, -O (CO) (NH) -,

-O (CO) - or - (CO) O- groups interrupted C ₂ -C ₂ o-alkylene, wherein said radicals may each be substituted by aryl, alkyl, aryloxy, alkyloxy, heteroatoms and / or heterocycles,

can mean

in which

for the case (1) in claim 1 in formula IR ^{1 is} hydrogen and at least one of the radicals R ³ to R ^{7 is} not hydrogen,

for the case (2) in claim 1 in formula II R ^{1 is} hydrogen and at least one of the radicals R ³ to R ^{10 is} not hydrogen,

for the case (3) in claim 1 in formula II R ^{1 is} not hydrogen and at least one of the radicals R ³ to R ^{10 is} not hydrogen,

in case (4) in claim 1 in formula MI R ¹ and R ⁵ are hydrogen and at least one of R ³ and R ^{4 is} not hydrogen and

for the case (5) in claim 1 in formula MI R ¹ and R ^{5 are} different from hydrogen and at least one of R ³ and R ^{4 is} not hydrogen.

3. The method according to any one of the preceding claims, characterized in that R ^{2 is} selected from the group comprising a single bond, methylene, 1, 1-ethylene, 1, 2-ethylene, 1, 1-propylene, 1, 2-propylene, 1, 3-propylene, 1, 1-dimethyl-1, 2-ethylene, 1, 4-butylene, 1, 6-hexylene, 2-methyl-1, 3-propylene, 2-ethyl-1, 3-propylene, 2,2-Dimethyl-1,3-propylene and 2,2-dimethyl-1,4-butylene, 3-methyl-1,5-pentylene, 3,5-heptylene, 1,2-cyclopentylene, 1, 3 Cyclopentylene, 1, 2 Cyclohexylene, 1, 3-cyclohexylene and ortho-phenylene.

4. The method according to any one of the preceding claims, characterized in that R ¹ and R ³ to R ^{10 are} independently selected from the group comprising hydrogen, Ci-C ₄ alkyl, n-hexyl, n-heptyl, n-octyl, n-decyl, n-dodecyl, n-tetradecyl, n-hexadecyl, n-octadecyl, n-eicosyl, 2-ethylhexyl, cyclopentyl, cyclohexyl, cyclooctyl, cyclododecyl, phenyl, naphthyl or benzyl.

5. The method according to any one of the preceding claims, characterized in that the diol is selected from the group comprising 2-ethyl-1, 3-hexanediol, 2-

Methyl 1,3-pentanediol, 2-propyl-1,3-heptanediol, 2,4-diethyloctane-1,5-diol, 2,2-dimethyl-1-phenyl-1,3-propanediol and 3,3- Dimethyl 1,2-butanediol.

6. Partially esterified (meth) acrylic acid esters (F) of dihydric diols (C) which contain different hydroxyl groups, with a color number according to DIN ISO 6271 below 500 APHA and a proportion of di (meth) acrylate in the sum of mono- and Di (meth) acrylate of the diols (C) of less than 5% by weight, obtained by

either

or

where the higher-substituted hydroxy group in position β bears at least one alkyl, cycloalkyl, aryl or aralkyl radical,

or (4) at least one diol (C ₄ ) having two primary hydroxyl groups, one of which carries at least one in position β and no alkyl, cycloalkyl, aryl or aralkyl radical in position β,

or

(5) at least one diol (Cs) having two secondary hydroxyl groups, one of which carries at least one in position β and no alkyl, cycloalkyl, aryl or aralkyl radical in position β,

in the presence of at least one catalyst (S) with (meth) acrylic acid esterified or at least one (meth) acrylic ester (D) transesterified, wherein the catalyst (S) in the case of a transesterification of the diol (C) with at least one (meth) acrylic acid ester (D) is selected from the group consisting of

(51) inorganic salts,

(52) metal salts having at least one cation selected from the group of alkaline earth metals, tin or titanium,

(53) alkali metal salts of C 1 to C 6 alkoxides,

(54) acids with a pKa of 0 to 3.

7. Partially esterified (meth) acrylic acid esters (F) according to claim 6 of the formula Ia

Formula IIa,

and formula IMa,

wherein

R ¹ to R ^{10 are} as defined in claim 2 and

R ^{11 is} hydrogen or methyl.

A process and partially esterified (meth) acrylic ester (F) according to any one of the preceding claims, characterized in that said at least one inorganic salt (S1) has a pKa of not more than 7.0 and not less than 1.0.

9. A process and partially esterified (meth) acrylic esters (F) according to any one of the preceding claims, characterized in that the at least one inorganic salt (S1) has a solubility in the reaction medium at 25 ⁰ C of not more than 1 g / l.

10. A process and partially esterified (meth) acrylic esters (F) according to any one of the preceding claims, characterized in that the catalyst (S1) is a heterogeneous inorganic salt having at least one anion selected from the group consisting from carbonate (CO ₃ ² ), hydrogen carbonate (HCO ₃ -), phosphate (PO ₄ ³ ), hydrogen phosphate (HPO ₄ ² ), dihydrogen phosphate (H ₂ PO ₄ ), sulfate (SO ₄ ² ), sulfite ( SO ₃ ² ) and carboxylate (R ⁶ -COO), in which R ^{6 is} C ₁ -C 18 -alkyl or C ₂ -C 18 which is optionally interrupted by one or more oxygen and / or sulfur atoms and / or one or more substituted or unsubstituted imino groups Alkyl or Ce - Ci ₂ aryl meaning tet.

11. A process and partially esterified (meth) acrylic esters (F) according to any one of the preceding claims, characterized in that the catalyst (S1) is a heterogeneous inorganic salt having at least one cation selected from the group consisting of alkali metals, alkaline earth metals, ammonium, cerium, iron, manganese, chromium, molybdenum, cobalt, nickel or zinc.

12. Process and partially esterified (meth) acrylic esters (F) according to one of the preceding claims, characterized in that the heterogeneous inorganic

Salt (S) is selected from the group consisting of LJsPO _4, K3PO4, Na3PO _4, K2CO3 and Na2CC "3 as well as their hydrates.

13. Use of a partially esterified (meth) acrylic ester (F) according to claim 6 to 12 or obtainable according to one of claims 1 to 5 or 8 to 12 as a monomer or comonomer in poly (meth) acrylates or as reactive diluent in thermal, radiation and / or dual-cure poly (meth) acrylates.

14. Use of a partially esterified (meth) acrylic ester (F) according to claim 6 to 12 or obtainable according to any one of claims 1 to 5 or 8 to 12 in PU dispersions, PU foams, PU adhesives and PU coatings.

15. Thermally, radiation or dual-cure coating compositions comprising at least one partially esterified (meth) acrylic acid ester (F) according to claim 6 to 12 or obtainable according to any one of claims 1 to 5 or 8 to 12.

16. Mixtures comprising at least one partially esterified (meth) acrylic ester (F) and at least one di (meth) acrylate of a diol (C) in which the weight ratio of partially esterified (meth) acrylic ester (F) to di (meth) acrylate a diol

(C) at least 99: 1 and the proportion of the di (meth) acrylate of the diol (C) is at least 0.01% by weight.