EP2948459A1

EP2948459A1 - New radiation-curable compounds and coating compositions

Info

Publication number: EP2948459A1
Application number: EP14700649.8A
Authority: EP
Inventors: Jürgen Baro; Monika CHARRAK; Reinhold Schwalm
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2013-01-25
Filing date: 2014-01-15
Publication date: 2015-12-02
Also published as: WO2014114534A1

Abstract

The present invention relates to new radiation-curable diacrylate compounds of formula (I) and radiation curable coating compositions comprising such compounds.

Description

New radiation-curable compounds and coating compositions

Description

The present invention relates to new radiation-curable compounds and radiation curable coating compositions comprising such compounds.

A very common component in radiation curable coatings is bisphenol A diglycidylether diacry- late, which is a widely used building block molecule and component in radiation curable coat- ings. Bisphenol A has been known to have esterogenic properties since the 1930's.

Unfortunately, the chemical bonds that link bisphenol A in polymer structures are not completely stable and the polymer may slowly decay with time, releasing small amounts of bisphenol A into materials with which it comes into contact, for example food or water. Recent studies have shown the widespread presence of tiny amounts of bisphenol A in many parts of the environment. Even at minute levels it may still exert estrogen-like effects on living organisms.

Jan Lukaszczyk et al., J. Mater. Sci: Mater Med (2012), 23: 1 149-1 155 disclose radiation curable methacrylates based on isosorbid diglycidyl ether as ingredients of dental compositions.

It is a disadvantage that these methacrylates exhibit very low activity as can be seen from a degree of double bond conversion of not more than 55%.

It was an object of the present invention to provide a curing-active new monomer which yields coatings with high flexibility and resistance, such as scratch resistance, and sufficient hardness

This object has been achieved by means of the new radiation curable diacrylate of formula (I),

wherein one radical out of R¹ and R² is acryloyl and the other is hydrogen and one radical out of R³ and R⁴ is acryloyl and the other is hydrogen.

Another object of the present invention are radiation-curable coating compositions comprising

Figuren 1 +2 (A) at least one compound of formula (I) and mixtures thereof,

(B) optionally at least one radiation-curable compound having precisely one free-radically polymerizable group,

(C) optionally at least one radiation-curable compound having precisely two free-radically polymerizable groups, and

(D) optionally at least one radiation-curable compound having more than two free-radically polymerizable groups.

Component (A) according to the invention is the new radiation curable diacrylate of formula (I),

wherein one radical out of R¹ and R² is acryloyl, and the other is hydrogen and one radical out of R³ and R⁴ is acryloyl, and the other is hydrogen.

Preferred components (A) are diacrylates of formula (la),

wherein the radicals R¹, R², R³, and R⁴ are defined as above. A very preferred component (A) is the diacrylate of formula (lb),

wherein the radicals R¹, R², R³, and R⁴ are defined as above.

Components (A) are preferably obtainable by reaction of the corresponding glycidyl ethers of anhydrosugars with acrylic acid.

Reaction conditions are known to the person skilled in the art, preferably the temperature is from 23 °C to 180 °C, very preferably from 40 to 160 °C, more preferably from 60 to 140 °C and especially preferably from 80 to 120 °C for 10 minutes to 12 hours, preferably from 15 minutes to 10 hours and very preferably from 30 minutes to 8 hours. Preferably a catalyst is added, e.g. tertiary amines, tertiary ammonium salts or triphenyl phosphine.

This reaction usually yields mixtures of acrylates as isomers. For example, mixtures of components of the above-mentioned formula (I) are obtained, in which R¹ is acryloyl and R² is hydro- gen, with those in which R¹ is hydrogen and R² is acryloyl. Similarly mixtures of components of the above-mentioned formula (I) are obtained, in which R³ is acryloyl and R⁴ is hydrogen, with those in which R³ is hydrogen and R⁴ is acryloyl.

Such mixtures preferably consist of the isomers of formula (I) as follows

with the proviso that the sum always adds up to 100 % by weight.

Such mixtures very preferably consist of the isomers of formula (I) as follows

with the proviso that the sum always adds up to 100 % by weight. The same distribution of isomers is possible for the components according to formula (la) and (lb).

Another conceivable way to obtain components (A) is by hydrolytic opening of the correspond- ing glycidyl ethers and esterification of the thus obtained alcohol (formula (I), R¹ = R² = R³ = R⁴ = hydrogen) with acrylic acid or transesterification with acrylic acid esters. This may lead to products according to the invention, in which more than two of the radicals R¹, R², R³, and R⁴ are acryloyl, for example on average 2 to 4, preferably 2 to 3.5, and more preferably 2.1 to 3. Anhydrosugars are obtainable by dehydration of hexitols, preferably galactitol, mannitol, and glucitol and less preferred allitol, altritol und iditol. The reaction is usually catalyzed by acids, preferably sulfuric acid.

Preferred anhydrosugars (bisanhydrohexitols) are isosorbide, isomannide, and isoidide, each of which may preferably be derived from renewable resources, such as plant-derived glucose, preferably isosorbide.

The preparation of glycidyl ethers of anhydrosugars is known, e.g. from M. Chrysanthos et al., Polymer 52 (201 1 ), 361 1 - 3620 or US 7,619,056 B2 and references cited therein.

As disclosed in M. Chrysanthos et al., Polymer 52 (201 1 ), 361 1 - 3620 , depending on the reaction conditions in the formation of glycidyl ethers of anhydrosugars, oligomers bearing glycidyl ether groups can be formed, which are capable of reacting with acrylic acids according to the present invention.

Therefore, products of formula (lc) are also an object of the present invention:

the radicals R¹, R², R³, and R⁴ are defined as above,

n is a positive integer, preferably from n=1 to 5, very preferably from n=1 to 4, more preferably from n=1 to 3 and especially preferably n=1 and n=2, and

R^a is hydrogen or a radical -CH₂-CHOR^b-CH₂OR^c,

wherein one radical out of R^b and R^c is acryloyl, and the other is hydrogen.

Preferably such components according to formula (lc) are based upon anhydrosugars derived from galactitol, mannitol, and glucitol and less preferred allitol, altritol und iditol, very preferably they are based on isosorbide, isomannide, and isoidide as anhydrosugars and especially preferably they are based on isosorbide.

In the latter case preferred components are those of formula (Id)

wherein

the radicals R¹, R², R³, R⁴ , R^a, R^b, and R^c, as well as n are defined as above. Another object of the present invention are mixtures of components of formula (I) with components of formula (Ic), more preferably mixtures of components of formula (lb) with components of formula (Id).

Such mixtures preferably consist of

- components of formula (I) 60 to 99 wt%, preferably 70 to 97 wt%, very preferably

75 to 95 wt% and especially preferably 80 to 90 wt%,

components of formula (Ic) with n=1 from 1 to 30 wt%, preferably from 2 to 25 wt%, very preferably from 5 to 20 wt% and especially preferably from 8 to 18 wt%,

components of formula (Ic) with n=2 from 0.1 to 15 wt%, preferably from 0.3 to 10 wt%, very preferably from 0.5 to 8 wt% and especially preferably from 1 to 5 wt%, and components of formula (Ic) with n=3 and higher in sum from 0.05 to 12 wt%, preferably from 0.1 to 10 wt%, very preferably from 0.2 to 8 wt% and especially preferably from 0.5 to 5 wt%,

components of formula (le) (see below) not more than 20 wt%, preferably not more than 15 wt%, very preferably from 0.05 to 10 wt% and especially preferably from 0.1 to 5 wt%, with the proviso, that the sum always adds up to 100 wt%.

Preferred mixtures consist of

components of formula (lb) 60 to 99 wt%, preferably 70 to 97 wt%, very preferably 75 to 95 wt% and especially preferably 80 to 90 wt%,

components of formula (Id) with n=1 from 1 to 30 wt%, preferably from 2 to 25 wt%, very preferably from 5 to 20 wt% and especially preferably from 8 to 18 wt%,

components of formula (Id) with n=2 from 0.1 to 15 wt%, preferably from 0.3 to 10 wt%, very preferably from 0.5 to 8 wt% and especially preferably from 1 to 5 wt%, and

- components of formula (Id) with n=3 and higher in sum from 0.05 to 12 wt%, preferably from 0.1 to 10 wt%, very preferably from 0.2 to 8 wt% and especially preferably from 0.5 to 5 wt%, components of formula (le) (see below) not more than 20 wt%, preferably not more than 15 wt%, very preferably from 0.05 to 10 wt% and especially preferably from

0.1 to 5 wt%,with the proviso, that the sum always adds up to 100 wt%.

Components of formula (le)

wherein the radicals R¹, R², R^a, R^b, and R^c, as well as n are defined as above, and n furthermore can be 0 (zero), are obtained by reaction of acrylic acid with glycidyl ethers of anhydrosugars, in which some hydroxy groups partly remain unreacted with epichlorohydrin. Such components still have free hydroxy groups. Such mixtures can be used like components according to formulae (I), (lb) or (lc) alone as described herein.

In a preferred embodiment such mixtures are obtained by reaction of acrylic acid with a mixture of glycidyl ethers of anhydrosugars and oligomers of anhydrosugars bearing glycidyl ether, wherein such mixtures of glycidyl ethers of anhydrosugars exhibit an epoxy equivalent weight of at least 200 g/eq, preferably at least 210 g/eq and very preferably at least 220 g/eq. Usually the epoxy equivalent weight of such mixtures is not more than 500 g/eq, preferably not more than 400, very preferably not more than 350 and especially not more than 300 g/eq. The epoxy equivalent weight (EEW) or weight per epoxy (WPE) is the weight in grammes of resin containing 1 mole equivalent of epoxide.

The molar amount of epoxide is usually determined according to ASTM D 1652. In general such glycidyl ethers of anhydrosugars optionally as a mixture with oligomers of anhydrosugars bearing glycidyl ether groups can be used to react with a surplus or unreacted acrylic acid in reaction mixtures for the production acrylic acid esters. Such a process is for example disclosed in EP-A-54 105, DE-A 33 16 593, EP-A-279 303, EP-A1 921 168 and WO

2004/055090. Usually the glycidyl ethers of anhydrosugars are reacted in equimolar amounts to the free acrylic acid in the reaction mixture. In a preferred embodiment such reaction mixtures can be obtained by reaction of acrylic acid with polyols, alkoxylated polyols or polyesterols in a molar ratio hydroxy groups : acrylic acid in the esterification for example 1 : 0.75 - 2.5, preferably 1 : 0.8 - 2, more preferably 1 : 0.9 - 1 .5, and very preferably 1 : 1 - 1 .2.

Preferred polyols are for example trimethylolbutane, tnmethylolpropane, trimethylolethane, neopentylglycol, pentaerythntol, ethylene glycol, 1 ,2-propanediol, 1 ,3-propanediol,

1 ,1 -dimethylethane-1 ,2-diol, 2-butyl-2-ethyl-1 ,3-propanediol, 2-ethyl-1 ,3-propanediol, 2-methyl- 1 ,3-propanediol, neopentyl glycol, neopentyl glycol hydroxypivalate, 1 ,2-, 1 ,3- or 1 ,4-butanediol, 1 ,6-hexanediol, 1 ,8-octanediol, 1 ,10-decanediol, 2-ethyl-1 ,3-hexanediol, 2-propyl-1 ,3-heptane- diol, and 2,4-diethyloctane-1 ,3-diol diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, preferably neopentylglycol, tnmethylolpropane, pentaerythntol, very preferably neopentylglycol, tnmethylolpropane, and pentaerythntol, and in particular tnmethylolpropane and pentaerythntol.

Preferred alkoxylated polyols are for example the above-mentioned polyols, preferably pentaerythntol, trimethylolethane or tnmethylolpropane with from single to 20-fold, more preferably from 5- to 20-fold, very preferably 10— 20-fold, and in particular 12— 20-fold ethoxylation, propoxylation or mixed ethoxylation and propoxylation, and in particular exclusively ethoxyla- tion.

Preferred polyesters are for example having a molar mass M_n of 1000 to 4000 g/mol and are preferably synthesized from the above-recited polyols or alkoxylated polyols with di- or higher carboxylic acids.

Very preferred polyesters are synthesized from aliphatic diols such as ethylene glycol, 1 ,2-propanediol, 1 ,3-propanediol, 1 ,1 -dimethylethane-1 ,2-diol, 2-butyl-2-ethyl-1 ,3-propanediol, 2-ethyl- 1 ,3-propanediol, 2-methyl-1 ,3-propanediol, neopentyl glycol, neopentyl glycol hydroxypivalate, 1 ,2-, 1 ,3- or 1 ,4-butanediol, 1 ,6-hexanediol, 1 ,10-decanediol, 2-ethyl-1 ,3-hexanediol, 2-propyl- 1 ,3-heptanediol, and 2,4-diethyloctane-1 ,3-diol and dicarboxylic acids, such as oxalic acid, ma- Ionic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, se- bacic acid, undecane-a,oo-dicar-boxylic acid, dodecane-a,oo-dicarboxylic acid, phthalic acid, isophthalic acid, terephthalic acid, 1 ,2-cyclohexanedicarboxylic acid, 1 ,4-cyclohexanedicarbo- xylic acid, 1 ,3-cyclohexanedicarboxylic acid, and 4-methyl-1 ,3-cyclohexanedicarboxylic acid.

In the reaction of the glycidyl ethers of anhydrosugars optionally as a mixture with oligomers of anhydrosugars bearing glycidyl ether groups with acrylic acid used in excess and/or unreacted, is bound in epoxide ester form, as are also, for example, hydroxy compounds still present as starting material in the mixture.

The reaction with epoxide compounds takes place preferably at from 90 to 130°C, more preferably from 100 to 1 10 °C, and is preferably continued until the reaction mixture has an acid number to DIN EN 3682 of less than 20, more preferably less than 15, very preferably less than 10 und especially less than 5 mg KOH/g (excluding solvent).

Catalysts which can be used for the reaction with the epoxide compounds include, for example, quaternary ammonium compounds and phosphonium compounds, tertiary amines, phosphines such as triphenylphosphine, and Lewis bases.

Component (B) is at least one, one to four for example, one to three for preference, more preferably one to two, and very preferably precisely one radiation-curable compound having precisely one free-radically polymerizable group.

Examples of free-radically polymerizable groups are vinyl ether or α,β-ethylenically unsaturated carboxylic acids, preferably (meth)acrylate groups, more preferably (meth)acrylate groups, and very preferably acrylate groups.

Monofunctional free-radically polymerizable compounds (B) are, for example, esters of α,β-ethyl-enically unsaturated carboxylic acids, preferably of (meth)acrylic acid, with alcohols containing 1 to 20 C atoms, preferably optionally hydroxyl-substituted alkanols containing 1 to 20 C atoms, e.g., methyl (meth)acrylate, ethyl (meth)acrylate, n-butyl (meth)acrylate, 2-ethyl- hexyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate or 4-hy- droxybutyl (meth)acrylate.

The monoethylenically unsaturated reactive diluent (B) may preferably be a compound (B1 ), comprising at least one cycloaliphatic group, or a compound (B2), comprising at least one heterocyclic group. Compounds (B1 ) are esters of (meth)acrylic acid with cycloalkanols or bicycloalkanols, the cy- cloalkanol or bicycloalkanol containing from 3 to 20 carbon atoms, preferably from 5 to 10 carbon atoms, and being optionally substituted by Ci to C₄ alkyl.

Examples of cycloalkanol and bicycloalkanol are cyclopentanol, cyclohexanol, cyclooctanol, cyclododecanol, 4-methylcyclohexanol, 4-isopropylcyclohexanol, 4-tert-butylcyclohexanol (preferably cis-configured), dihydrodicyclopentadienyl alcohol, and norbornyl alcohol. Preference is given to cyclohexanol and 4-tert-butylcyclohexanol.

As component (B2) it is possible in principle to use all monofunctional esters of α,β-ethylenically unsaturated carboxylic acids with a monofunctional alkanol that has as a structural element at least one saturated 5- or 6-membered heterocycle having one or two oxygen atoms in the ring. Component (B) derives preferably from acrylic acid or methacrylic acid. Examples of suitable compounds of component (B2) comprise compounds of the general formula (I II)

(III) in which R⁷ is selected from H and CH3 and more particularly is H, k is a number from 0 to 4 and more particularly 0 or 1 , and

Y is a 5- or 6-membered, saturated heterocycle having one or two oxygen atoms, the heter- ocycle being optionally substituted by C1-C4 alkyl, e.g., methyl, ethyl, n-propyl, isopropyl, n-butyl, 2-butyl, isobutyl or tert-butyl.

The 5- or 6-membered saturated heterocycle derives preferably from tetrahydrofuran, tetrahy- dropyran, 1 ,3-dioxolane or 1 ,3- or 1 ,4-dioxane.

With particular preference component (B2) is selected from trimethylolpropane monoformal acrylate, glycerol monoformal acrylate, 4-tetrahydropyranyl acrylate, 2-tetrahydropyranyl methylacrylate, tetrahydrofurfuryl acrylate, and mixtures of these. Very particular preference is given to using trimethylolpropane monoformal acrylate as component (B2).

Also conceivable, however, albeit less preferred, are vinylaromatic compounds, e.g., styrene, divinylbenzene, α,β-unsaturated nitriles, e.g., acrylonitrile, methacrylonitrile, α,β-unsaturated aldehydes, e.g., acrolein, methacrolein, vinyl esters, e.g., vinyl acetate, vinyl propionate, halo- genated ethylenically unsaturated compounds, e.g., vinyl chloride, vinylidene chloride, conju- gated unsaturated compounds, e.g., butadiene, isoprene, chloroprene, monounsaturated compounds, e.g., ethylene, propylene, 1 -butene, 2-butene, isobutene, cyclic monounsaturated compounds, e.g., cyclopentene, cyclohexene, cyclododecene, N-vinylformamide, allylacetic acid, vinylacetic acid, monoethylenically unsaturated carboxylic acids having 3 to 8 C atoms and also their water-soluble alkali metal, alkaline earth metal or ammonium salts, such as, for example: acrylic acid, methacrylic acid, dimethylacrylic acid, ethylacrylic acid, maleic acid, citraconic acid, methylenemalonic acid, crotonic acid, fumaric acid, mesaconic acid, and itaconic acid, maleic acid, N-vinylpyrrolidone, N-vinyl lactams, such as N-vinylcaprolactom, N-vinyl-N-alkylcarbox- amides or N-vinylcarboxamides, such as N-vinylacetamide, N-vinyl-N-methylformamide, and N-vinyl-N-methylacetamide, or vinyl ethers, examples being methyl vinyl ether, ethyl vinyl ether, n-propyl vinyl ether, isopropyl vinyl ether, n-butyl vinyl ether, sec-butyl vinyl ether, isobutyl vinyl ether, tert-butyl vinyl ether, 4-hydroxybutyl vinyl ether, and also mixtures of these.

Component (C) is at least one, one to four for example, one to three for preference, more preferably one to two, and very preferably precisely one radiation-curable compound having pre- cisely two free-radically polymerizable groups.

Component (D) is at least one, one to four for example, one to three for preference, more preferably one to two, and very preferably precisely one radiation-curable compound having more than 2, preferably 3-10, more preferably 3-6, very preferably 3-4, and more particularly 3 free- radically polymerizable groups.

Preferably components (C) and (D) are selected independently of one another from the group consisting of polyfunctional (meth)acrylic esters (C1 ) and/or (D1 )

polyester (meth)acrylates (C2) and/or (D2)

polyether (meth)acrylates (C3) and/or (D3)

urethane (meth)acrylate (C4) and/or (D4)

- epoxy (meth)acrylates (C5) and/or (D5)

(meth)acrylated polyacrylates (C6) and/or (D6), or

carbonate (meth)acrylates (C7) and/or (D7).

These may for example be esters of α,β-ethylenically unsaturated carboxylic acids, preferably of (meth)acrylic acid, more preferably of acrylic acid with polyalcohols having a corresponding functionality of at least two.

Suitable examples of polyalcohols of this kind are at least dihydric polyols, polyetherols or poly- esterols or polyacrylatepolyols having an average OH functionality of at least 2, preferably 3 to 10.

Examples of polyfunctional polymerizable compounds (C1 ) are ethylene glycol diacrylate,

1 .2- propanediol diacrylate, 1 ,3-propanediol diacrylate, 1 ,4-butanediol diacrylate, 1 ,3-butanediol diacrylate, 1 ,5-pentanediol diacrylate, 1 ,6-hexanediol diacrylate, 1 ,8-octanediol diacrylate, neo- pentyl glycol diacrylate, 1 ,1 -, 1 ,2-, 1 ,3-, and 1 ,4-cyclohexanedimethanol diacrylate, and 1 ,2-,

1 .3- or 1 ,4-cyclohexandiol diacrylate.

Examples of polyfunctional polymerizable compounds (D1 ) are trimethylolpropane triacrylate, ditrimethylolpropane pentaacrylate or hexaacrylate, pentaerythritol triacrylate or tetraacrylate, glycerol diacrylate or triacrylate, and also diacrylates and polyacrylates of sugar alcohols, such as of sorbitol, mannitol, diglycerol, threitol, erythritol, adonitol (ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol), maltitol or isomalt, for example.

Further examples of (C1 ) and/or (D1 ) are (meth)acrylates of compounds of the formula (I la) to (lid),

(Ma) (lib) (lie)

(lid) in which R⁵ and R⁶ independently of one another are hydrogen or are C1-C18 alkyl optionally substituted by aryl, alkyl, aryloxy, alkyloxy, heteroatoms and/or heterocycles, u, v, w, and x independently of one another are each an integer from 1 to 10, preferably 1 to 5, and more preferably 1 to 3, and each Xi, for i = 1 to u, 1 to v, 1 to w, and 1 to x, can be selected independently of the others from the group -CH2-CH2-O-, -CH₂-CH(CH₃)-0-, -CH(CH₃)-CH₂-0-,

-CH₂-C(CH₃)₂-0-, -C(CH₃)₂-CH₂-0-, -CH₂-CHVin-0-, -CHVin-CH₂-0-, -CH₂-CHPh-0-, and -CHPh-CH₂-0-, preferably from the group -CH₂-CH₂-0-, -CH₂-CH(CH₃)-0-, and -CH(CH₃)- CH2-O-, and more preferably -CH₂-CH₂-0-, in which Ph is phenyl and Vin is vinyl.

In these definitions, C1-C18 alkyl optionally substituted by aryl, alkyl, aryloxy, alkyloxy, heteroa- toms and/or heterocycles is 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, hexadecyl, octadecyl, 1 ,1 -dimethylpropyl, 1 ,1 -dimethylbutyl, 1 ,1 ,3,3-tetramethylbutyl, preferably methyl, ethyl or n-propyl, very preferably methyl or ethyl. The compounds in question are preferably (meth)acrylates of singly to vigintuply and, more preferably, triply to decuply ethoxylated, propoxylated or mixedly ethoxylated and propoxylated, and more particularly exclusively ethoxylated, neopentyl glycol, trimethylolpropane, trime- thylolethane or pentaerythritol. Preferred polyfunctional polymerizable compounds are ethylene glycol diacrylate, 1 ,2-propan- ediol diacrylate, 1 ,3-propanediol diacrylate, 1 ,4-butanediol diacrylate, 1 ,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and triacrylate of singly to vigintuply alkoxylated, more preferably ethoxylated, trimethylolpropane. Especially preferred polyfunctional polymerizable compounds are 1 ,4-butanediol diacrylate, 1 ,6-hexanediol diacrylate, trimethylolpropane triacrylate, pentaerythritol tetraacrylate, and tri- acrylate of singly to vigintuply ethoxylated trimethylolpropane. Polyester (meth)acrylates (C2) and/or (D2) are the corresponding esters of α,β-ethylenically unsaturated carboxylic acids, preferably of (meth)acrylic acid, more preferably of acrylic acid, with polyesterpolyols.

Polyesterpolyols are known for example from UHmanns Encyklopadie der technischen Chemie, 4th Edition, Volume 19, pp. 62 to 65. Preference is given to using polyesterpolyols obtained by reacting dihydric alcohols with dibasic carboxylic acids. In place of the free polycarboxylic acids it is also possible to use the corresponding polycarboxylic anhydrides or corresponding polycarboxylic esters of lower alcohols, or mixtures thereof, to prepare the polyesterpolyols. The polycarboxylic acids may be aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic and may if desired be substituted, by halogen atoms for example, and/or unsaturated. Examples thereof that may be mentioned include the following: oxalic acid, maleic acid, fumaric acid, succinic acid, glutaric acid, adipic acid, sebacic acid, do- decanedioic acid, o-phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, azelaic acid, 1 ,4-cyclohexanedicarboxylic acid or tetrahydrophthalic acid, suberic acid, azelaic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylenetetrahydrophthalic anhydride, glutaric anhydride, maleic anhydride, di- meric fatty acids, their isomers and hydrogenation products, and also esterifiable derivatives, such as anhydrides or dialkyl esters, such as C1-C4 alkyl esters, preferably methyl, ethyl or n- butyl esters, of the stated acids are employed. Preference is given to dicarboxylic acids of the general formula HOOC-(CH2)_y-COOH, y being a number from 1 to 20, preferably an even number from 2 to 20, and particular preference to succinic acid, adipic acid, sebacic acid, and do- decanedicarboxylic acid. Polyhydric alcohols contemplated for the preparation of the polyesterols include 1 ,2-propane- diol, ethylene glycol, 2, 2-dimethyl-1 ,2-ethanediol, 1 ,3-propanediol, 1 ,2-butanediol, 1 ,3-butane- diol, 1 ,4-butanediol, 3-methylpentane-1 ,5-diol, 2-ethylhexane-1 ,3-diol, 2,4-diethyloctane-1 ,3- diol, 1 ,6-hexanediol, polyTHF with a molar mass between 162 and 2000, poly-1 ,3-propanediol with a molar mass between 134 and 1 178, poly-1 ,2-propanediol with a molar mass between 134 and 898, polyethylene glycol with a molar mass between 106 and 458, neopentyl glycol, neopentyl glycol hydroxypivalate, 2-ethyl-1 ,3-propanediol, 2-methyl-1 ,3-propanediol, 2,2-bis(4- hydroxycyclohexyl)propane, 1 ,1 -, 1 ,2-, 1 ,3-, and 1 ,4-cyclohexanedimethanol, 1 ,2-, 1 ,3- or 1 ,4- cyclohexanediol, trimethylolbutane, trimethylolpropane, trimethylolethane, neopentyl glycol, pentaerythritol, glycerol, ditrimethylolpropane, dipentaerythritol, sorbitol, mannitol, diglycerol, threitol, erythritol, adonitol (ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol), maltitol or isomalt, which if desired may be alkoxylated as described above.

Preference is given to alcohols of the general formula HO-(CH2)x-OH, x being a number from 1 to 20, preferably an even number from 2 to 20. Preference is given to ethylene glycol, butane- 1 ,4-diol, hexane-1 ,6-diol, octane-1 ,8-diol, and dodecane-1 ,12-diol. Preference additionally is given to neopentyl glycol. Also contemplated, furthermore, are polycarbonatediols of the kind obtainable, for example, by reacting phosgene with an excess of the low molecular mass alcohols specified as synthesis components for the polyesterpolyols.

Also suitable are lactone-based polyesterdiols, which are homopolymers or copolymers of lac- tones, preferably hydroxyl-terminated adducts of lactones with suitable difunctional starter molecules. Lactones contemplated are preferably those deriving from the compounds of the general formula HO-(CH2)_z-COOH, z being a number from 1 to 20, and it also being possible for one H atom of a methylene unit to have been substituted by a Ci to C₄ alkyl radical. Examples are ε-caprolactone, β-propiolactone, gamma-butyrolactone and/or methyl-e-caprolactone, 4-hy- droxybenzoic acid, 6-hydroxy-2-naphthoic acid or pivalolactone, and also their mixtures. Suitable starter components are, for example, the low molecular mass dihydric alcohols specified above as a synthesis component for the polyesterpolyols. The corresponding polymers of ε-caprolactone are particularly preferred. Lower polyesterdiols or polyetherdiols can also be used as starters for preparing the lactone polymers. In place of the polymers of lactones it is also possible to use the corresponding, chemically equivalent polycondensates of the hydroxyl- carboxylic acids corresponding to the lactones.

Polyether (meth)acrylates (C3) and/or (D3) are the corresponding esters of α,β-ethylenically unsaturated carboxylic acids, preferably of (meth)acrylic acid, more preferably of acrylic acid, with polyetherols.

The polyetherols are preferably polyethylene glycol with a molar mass between 106 and 2000, preferably 106 to 1500, more preferably 106 to 1000, poly-1 ,2-propanediol with a molar mass between 134 and 1 178, poly-1 ,3-propanediol with a molar mass between 134 and 1 178, and polytetrahydrofurandiol having a number-average molecular weight M_n in the range from about 500 to 4000, preferably 600 to 3000, more particularly 750 to 2000.

Urethane (meth)acrylates (C4) and/or (D4) are obtainable, for example, by reacting polyisocya- nates with hydroxyalkyl (meth)acrylates or hydroxyalkyl vinyl ethers and, if desired, chain ex- tenders such as diols, polyols, diamines, polyamines or dithiols or polythiols. Urethane (meth)- acrylates dispersible in water without addition of emulsifiers additionally comprise ionic and/or nonionic hydrophilic groups, which are introduced into the urethane through synthesis components, for example, such as hydroxycarboxylic acids.

Such urethane (meth)acrylates substantially comprise as synthesis components:

(a) at least one organic aliphatic, aromatic or cycloaliphatic di- or polyisocyanate, (b) at least one compound having at least one isocyanate-reactive group and at least one free-radically polymerizable unsaturated group, and

(c) if desired, at least one compound having at least two isocyanate-reactive groups.

The urethane (meth)acrylates preferably have a number-average molar weight M_n of 500 to 20 000, more particularly of 500 to 10 000, with particular preference 600 to 3000 g/mol (as determined by gel permeation chromatography using tetrahydrofuran and polystyrene as standard).

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

Epoxide (meth)acrylates (C5) and/or (D5) are obtainable by reacting epoxides with (meth)acrylic acid. Examples of epoxides contemplated include epoxidized olefins, aromatic glycidyl ethers or aliphatic glycidyl ethers, preferably those of aromatic or aliphatic glycidyl ethers.

Epoxidized olefins may for example be ethylene oxide, propylene oxide, isobutylene oxide, 1 -butene oxide, 2-butene oxide, vinyloxirane, styrene oxide or epichlorohydrin, preference being given to ethylene oxide, propylene oxide, isobutylene oxide, vinyloxirane, styrene oxide or epichlorohydrin, particular preference to ethylene oxide, propylene oxide or epichlorohydrin, and very particular preference to ethylene oxide and epichlorohydrin.

Aromatic glycidyl ethers are, for example, bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, bisphenol B diglycidyl ether, bisphenol S diglycidyl ether, hydroquinone diglycidyl ether, alkylation products of phenol/dicyclopentadiene, e.g., 2,5-bis[(2,3-epoxypropoxy)phenyl]octa- hydro-4,7-methano-5H-indene) (CAS No. [13446-85-0]), tris[4-(2,3-epoxypropoxy)phenyl]- methane isomers) (CAS No. [66072-39-7]), phenol-based epoxy novolaks

(CAS No. [9003-35-4]), and cresol-based epoxy novolaks (CAS No. [37382-79-9]).

Aliphatic glycidyl ethers are, for example, 1 ,4-butanediol diglycidyl ether, 1 ,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, 1 ,1 ,2,2-tetra- kis[4-(2,3-epoxypropoxy)phenyl]ethane (CAS No. [27043-37-4]), diglycidyl ethers of polypropylene glycol (a,(jo-bis(2,3-epoxypropoxy)poly(oxypropylene) (CAS No. [16096-30-3]) and of hy- drogenated bisphenol A (2,2-bis[4-(2,3-epoxypropoxy)cyclohexyl]propane,

CAS No. [13410-58-7]).

The epoxide (meth)acrylates and epoxide vinyl ethers preferably have a number-average molar weight M_n of 200 to 20 000, more preferably of 200 to 10 000 g/mol, and very preferably of 250 to 3000 g/mol; the (meth)acrylic group or vinyl ether group content is preferably 1 to 5, more preferably 2 to 4 per 1000 g of epoxide (meth)acrylate or vinyl ether epoxide (as determined by gel permeation chromatography using polystyrene as standard and tetrahydrofuran as eluent). (Meth)acrylated polyacrylates (C6) and/or (D6) are the corresponding esters of α,β-ethylenically unsaturated carboxylic acids, preferably of (meth)acrylic acid, more preferably of acrylic acid, with polyacrylate polyols. Polyacrylate polyols of this kind preferably have molecular weight M_n of at least 1000, more preferably at least 2000, and very preferably at least 5000 g/mol. The molecular weight M_n can for example be up to 200 000, preferably up to 100 000, more preferably up to 80 000, and very preferably up to 50 000 g/mol. Preferred OH numbers of polyacrylate polyols, measured in accordance with DIN 53240-2, are 15-250 mg KOH/g, preferably 80-160 mg KOH/g.

Additionally the polyacrylate polyols may have an acid number in accordance with DIN EN ISO 3682 of up to 200 mg KOH/g, preferably up to 150, and more preferably up to 100 mg KOH/g.

The polyacrylate polyols are copolymers of at least one (meth)acrylic ester with at least one compound having at least one, preferably precisely one hydroxyl group and at least one, preferably precisely one (meth)acrylate group. The latter may be, for example, monoesters of α,β-unsaturated carboxylic acids, such as acrylic acid, methacrylic acid (referred to in this document for short as "(meth)acrylic acid"), with diols or polyols, which have preferably 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, penta- ethylene glycol, tripropylene glycol, 1 ,4-butanediol, 1 ,5-pentanediol, neopentyl glycol, neopentyl glycol hydroxypivalate, 2-ethyl-1 ,3-propanediol, 2-methyl-1 ,3-propanediol, 2-butyl-2-ethyl-1 ,3- propanediol, 1 ,6-hexanediol, 2-methyl-1 ,5-pentanediol, 2-ethyl-1 ,4-butanediol, 2-ethyl-1 ,3-he- xanediol, 2,4-diethyloctane-1 ,3-diol, 2,2-bis(4-hydroxycyclohexyl)propane, 1 ,1 -, 1 ,2-, 1 ,3-, and 1 ,4-bis(hydroxymethyl)cyclohexane, 1 ,2-, 1 ,3- or 1 ,4-cyclohexanediol, glycerol, trimethylol- ethane, trimethylolpropane, trimethylolbutane, pentaerythritol, ditrimethylolpropane, dipenta- rythritol, sorbitol, mannitol, diglycerol, threitol, erythritol, adonitol (ribitol), arabitol (lyxitol), xylitol, dulcitol (galactitol), maltitol, isomalt, polyTHF with a molar weight between 162 and 4500, preferably 250 to 2000, poly-1 ,3-propanediol or polypropylene glycol with a molar weight beween 134 and 2000, or polyethylene glycol with a molar weight between 238 and 2000.

Preference is given to 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2- or 3-hydroxypro- pylacrylate, 1 ,4-butanediol monoacrylate or 3-(acryloyloxy)-2-hydroxypropyl acrylate, and particular preference to 2-hydroxyethyl acrylate and/or 2-hydroxyethyl methacrylate. The monomers which carry hydroxyl groups are used in the copolymerization in a mixture with other polymerizable monomers, preferably free-radically polymerizable monomers, preferably those composed to an extent of more than 50% by weight of C1-C20, preferably Ci to C₄ alkyl (meth)acrylate, (meth)acrylic acid, vinylaromatics having up to 20 C atoms, vinyl esters of car- boxylic acids comprising up to 20 C atoms, vinyl halides, nonaromatic hydrocarbons having 4 to 8 C atoms and 1 or 2 double bonds, unsaturated nitriles, and mixtures of these. Particularly preferred are the polymers composed to an extent of more than 60% by weight of Ci-Cio-alkyl (meth)acrylates, styrene, vinylimidazole or mixtures of these.

The polymers may further comprise hydroxyl-functional monomers corresponding to the above hydroxyl group content, and, if desired, further monomers, examples being glycidyl epoxy esters of (meth)acrylic acid, or ethylenically unsaturated acids, more particularly carboxylic acids, acid anhydrides or acid amides.

Carbonate (meth)acrylates (C7) and/or (D7) are likewise obtainable with different functionalities.

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, more preferably less than 800 g/mol (as determined by gel permeation chromatography using polystyrene as standard; solvent: tetrahy- drofuran).

The carbonate (meth)acrylates are obtainable in a simple way by transesterification of carbonic esters with polyhydric, preferably dihydric, alcohols (diols, e.g., hexanediol) and subsequent esterification of the free OH groups with (meth)acrylic acid, or else transesterification with (meth)acrylic esters, as described in EP-A 92 269, for example. They are also obtainable by reaction of phosgene, urea derivatives with polyhydric alcohols, dihydric alcohols for example.

Obtainable in a similar way are vinyl ether carbonates, by reaction of a hydroxyalkyl vinyl ether with carbonic esters and also, if desired, dihydric alcohols.

Also conceivable are (meth)acrylates or vinyl ethers of polycarbonate polyols, such as the reaction product of one of the stated diols or polyols and a carbonic ester and also a hydroxyl- containing (meth)acrylate or vinyl ether.

Examples of suitable carbonic esters are ethylene carbonate, 1 ,2- or 1 ,3-propylene carbonate, dimethyl carbonate, diethyl carbonate or dibutyl carbonate.

Examples of suitable hydroxyl-containing (meth)acrylates are 2-hydroxyethyl (meth)acrylate, 2- or 3-hydroxypropyl (meth)acrylate, 1 ,4-butanediol mono(meth)acrylate, neopentyl glycol mono(meth)acrylate, glycerol mono(meth)acrylate and di(meth)acrylate, trimethylolpropane mono(meth)acrylate and di(meth)acrylate, and also pentaerythritol mono(meth)acrylate, di(meth)acrylate, and tri(meth)acrylate. Examples of suitable hydroxyl-containing vinyl ethers are 2-hydroxyethyl vinyl ether and 4- hydroxybutyl vinyl ether.

Particularly preferred carbonate (meth)acrylates are those of the formula: in which R is H or CH3, X is a C2-C18 alkylene group, and n is an integer from 1 to 5, preferably from 1 to 3.

R is preferably H, and X is preferably C₂ to C10 alkylene, exemplified by 1 ,2-ethylene, 1 ,2-pro- pylene, 1 ,3-propylene, 1 ,4-butylene or 1 ,6-hexylene, or more preferably C₄ to Cs alkylene. With very particular preference X is C6 alkylene.

The carbonate (meth)acrylates are prefererably aliphatic carbonate (meth)acrylates.

Particular preference among the polyfunctional polymerizable compounds is given to urethane (meth)acrylates (C4) and/or (D4).

In a preferred embodiment of the present invention at least one of the components, (C) or (D), has a diol as a synthesis component, selected from the group consisting of

polytetrahydrofurandiol (H-[-0-CH2-CH₂-CH2-CH₂-]k-OH),

polyethylene glycol (H-[-0-CH₂-CH₂-]k-OH),

polypropylene glycol, H-[-0-CH₂-CH(CH₃)-]_k-OH

polycaprolactonediol (-[-0-CH₂-CH₂-CH₂-CH₂-CH₂-(CO)-]_k-R⁸-OH), and

polyesterdiol (HO-[R⁸-0-(CO)-R⁹-(CO)-0-R⁸-]_k-OH) with a number-average molar mass of 500 to 4000. In the above formulae

R⁸ and R⁹ independently of one another are a divalent aliphatic or cycloaliphatic radical having at least one carbon atom and

k is a positive integer needed in order to obtain the molar mass in question.

Preferred radicals R⁸ and R⁹ are, independently of one another, methylene, 1 ,2-ethylene, 1 ,2-propylene, 1 ,3-propylene, 1 ,2-, 1 ,3- or 1 ,4-butylene, 1 ,1 -dimethyl-1 ,2-ethylene or 1 ,2-di- methyl-1 ,2-ethylene, 1 ,5-pentylene, 1 ,6-hexylene, 1 ,8-octylene, 1 ,10-decylene or 1 ,12-do- decylene.

Diols of this kind further enhance the flexibility of the resulting coatings.

Based on the sum of the compounds (A), (B), (C), and (D), the coating compositions of the vention may further comprise 0% to 10% by weight of at least one photoinitiator (E). Photoinitiators (E) may be, for example, photoinitiators known to the skilled worker, examples being those specified 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 (ed.), SUA Technology Ltd, London.

Suitable photoinitiators are those of the kind described in WO 2006/005491 A1 , page 21 , line 18 to page 22, line 2 (corresponding to US 2006/0009589 A1 , paragraph [0150]), which is hereby incorporated by reference as part of the present disclosure.

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

Preference among these photoinitiators is given to 2,4,6-trimethylbenzoyldiphenylphosphine oxide, ethyl 2,4,6-trimethylbenzoylphenylphosphinate, bis(2,4,6- trimethylbenzoyl)phenylphosphine oxide, benzophenone, 1 -benzoylcyclohexan-1 -ol, 2-hydroxy- 2,2-dimethylacetophenone, and 2,2-dimethoxy-2-phenylacetophenone.

Based on the sum of the compounds (A), (B), (C), and (D), the coating compositions of the in- vention may further comprise 0% to 10% by weight of further, typical coatings additives (F).

Examples of further typical coatings additives (F) that can be used include antioxidants, stabilizers, activators (accelerants), fillers, pigments, dyes, antistats, flame retardants, thickeners, thixotropic agents, surface-active agents, viscosity modifiers, plasticizers or chelating agents.

It is further possible to add one or more thermally activable initiators, examples being potassium peroxodisulfate, dibenzoyl peroxide, cyclohexanone peroxide, di-tert-butyl peroxide, azobisiso- butyronitrile, cyclohexylsulfonyl acetyl peroxide, diisopropyl percarbonate, tert-butyl peroctoate or benzpinacol, and also, for example, those thermally activable initiators which have a half-life at 80°C of more than 100 hours, such as di-tert-butyl peroxide, cumene hydroperoxide, dicumyl peroxide, tert-butyl perbenzoate, silylated pinacols, which are available commercially under the trade name ADDID 600 from Wacker, for example, 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.

Thickeners contemplated include not only free-radically (co)polymerized (co)polymers but also typical organic and inorganic thickeners such as hydroxymethylcellulose or bentonite.

Examples of chelating agents which can be used include ethylenediamineacetic acid and the salts thereof, and also β-diketones. Suitable fillers comprise silicates, examples being silicates obtainable by silicon tetrachloride hydrolysis, such as Aerosil^® from Degussa, silicious earth, talc, aluminum silicates, magnesium silicates, and calcium carbonates, etc. Suitable stabilizers comprise typical UV absorbers such as oxanilides, triazines, and benzotria- zole (the latter available as Tinuvin^® products from Ciba-Spezialitatenchemie), and benzophe- nones. They can be used alone or together with suitable free-radical scavengers, examples being sterically hindered amines such as 2,2,6,6-tetramethylpiperidine, 2,6-di-tert-butylpiperi- dine or derivatives thereof, such as bis(2,2,6,6-tetramethyl-4-piperidyl) sebacate, for example. Stabilizers are used typically in amounts from 0.1 % to 5.0% by weight, based on the solid components comprised in the preparation.

The coating compositions may further comprise a solvent, examples being butyl acetate, ethyl acetate, methoxypropyl acetate, toluene, xylene, fluorinated aromatics, and aliphatic and aro- matic hydrocarbon mixtures.

Preferably, however, the coating compositions are applied free from solvent.

The coating compositions of the invention are suitable as molding compounds, as for example in films or tubes which may optionally be reinforced with fibers or for coating substrates such as wood, paper, textile, leather, nonwoven, plastics surfaces, glass, ceramic, mineral building materials, such as molded cement bricks and fiber cement slabs, or coated or uncoated metals, preferably plastics or metals, more particularly in the form of films or foils, and with particular preference metals.

The coating materials can be employed in particular in primers, surfacers, pigmented topcoat materials and clearcoat materials in the field of automotive refinish or large-vehicle finishing, and aircraft. Coating materials of this kind are particularly suitable for applications requiring particularly high levels of application reliability, external weathering resistance, hardness, and flexi- bility, such as in automotive refinish large-vehicle finishing and industrial coatings.

The coating compositions of the invention are especially employed as or in automotive clearcoat and topcoat material(s). It is an advantage of coating compositions according to the invention that they are suitable for exterior coating, since they more colour stable than bisphenol A diglycidylether diacrylate, which tends to yellowing on exposure to UV- or daylight.

Coating compositions according to the present invention are furthermore useful as or for pro- ducing formulations, preferably printing inks for flexographic, screenprinting, lithographic, letterpress, gravure or ink-jet printing or in overprint varnishes.

The dry layer thickness in which such printing inks of the present invention are applied to the substrate differs with each printing method and can typically be up to 20 μηη, preferably in the range from 0.1 to 8 μηη, more preferably in the range from 0.2 to 7 μηη, even more preferably in the range from 1 to 5 μηη and particularly in the range from 1 to 4 μηη.

Typical printing ink layer thicknesses are 1 to 8 μηη for flexographic printing, 1 - 4 μηη for offset printing, 1 - 12 μηη for gravure printing.

Present invention printing inks for printing processes are curable by actinic radiation. Actinic radiation having a wavelength range from 200 nm to 700 nm is useful for example. Actinic radiation having an energy in the range from 30 mJ/cm² to 2000 mJ/cm² is useful for example. Actinic radiation may advantageously be applied continuously or in the form of flashes for example.

A preferred embodiment of the present invention comprises effecting the curing of the printing inks by means of electron radiation in suitable electron flash devices, for example at an energy in the range from 50 to 300 keV, preferably from 90 to 200 keV. One advantage of performing the curing by means of electron radiation is that the printing inks thus cured are generally more resistant to rubbing than printing inks cured with UV light.

When curing is effected by means of electron radiation, the printing ink of the present invention preferably does not comprise any photoinitiator (E). This has the advantage that no migratable photoinitiator constituents remain in the coating which have been formed by irradiation. This is particularly of advantage when the coatings are intended for food contact.

The distance of the electron flash devices to the printing surface is between 1 and 100 cm, preferably 2 to 50 cm.

Further preferred fields of use are can coating and coil coating.

Coil coating is the continuous coating of metal strips with coating materials, usually liquid coating materials. Rolled metal strips, after production, are wound up into rolls (referred to as "coils") for the purposes of storage and transport. These metal strips represent the starting material for the majority of sheetlike metallic workpieces, examples being automobile parts, bodywork parts, instrument paneling, exterior architectural paneling, ceiling paneling or window profiles, for example. For this purpose the appropriate metal sheets are shaped by means of appropriate techniques such as punching, drilling, folding, profiling and/or deep drawing. Larger compo- nents, such as automobile bodywork parts, for example, are optionally assembled by welding together a number of individual parts.

For the coating operation, metal strips with a thickness of 0.2 to 2 mm and a width of up to 2 m are transported at a speed of up to 200 m/min through a coil coating line, and are coated in the process. For this purpose it is possible to use, for example, cold-rolled strips of soft steels or construction-grade steels, electrolytically galvanized thin sheet, hot-dip-galvanized steel strip, or strips of aluminum or aluminum alloys. Typical lines comprise a feed station, a coil store, a cleaning and pretreatment zone, a first coating station along with baking oven and downstream cooling zone, a second coating station with oven, laminating station, and cooling, and also a coil store and winder.

Characteristic of coil coatings are thin films of the coating compositions, with a dry film thickness of usually well below 80 μηη, often below 60 μηη, below 50 μηη, and even below 40 μηη. Furthermore, the metal sheets are processed with a high throughput, which necessitates short residence times, i.e., necessitates drying at an elevated temperature following application of the coating, in order that the coating composition soon acquires load-bearing qualities. It may furthermore be possible to use coating compositions according to the present invention in radiation curable adhesives and in manufacturing processes of optical fibers or printed circuit board.

Coating of the substrates with the coating compositions of the invention takes place in accord- ance with typical processes known to the skilled worker, a coating composition of the invention or a paint formulation comprising it being applied in the desired thickness to the target substrate and optionally dried. This operation may if desired be repeated one or more times. Application to the substrate may take place in a known way, as for example by spraying, troweling, knife- coating, brushing, rolling, roller coating, pouring, laminating, injection backmolding or coextrud- ing. The coating material may also be applied electrostatically in the form of powder (powder coating materials).

Further disclosed is a method of coating substrates which involves applying to the substrate a coating composition of the invention or a paint formulation comprising it, optionally admixed with further, typical coatings additives and thermally, chemically or radiation-curable resins, optionally drying the applied coating, curing it with electron beams or UV exposure under an oxygen- containing atmosphere or, preferably, under inert gas.

Radiation curing takes place with high-energy light, UV light for example, or electron beams. Radiation curing may take place at relatively high temperatures. Preference is given in that case to a temperature above the T_g of the radiation-curable binder.

Besides radiation curing there may also be further curing mechanisms involved, examples being thermal curing, moisture curing, chemical curing and/or oxidative curing, preferably thermal and radiation curing, and more preferably radiation curing alone.

The coating materials may be applied one or more times by any of a very wide variety of spraying methods, such as compressed-air, airless or electrostatic spraying methods, using one- or two-component spraying units, or else by injecting, troweling, knifecoating, brushing, rolling, roller coating, pouring, laminating, injection backmolding or coextruding.

The coating thickness is generally in a range from about 3 to 1000 g/m² and preferably 10 to 200 g/m². Drying and curing of the coatings take place generally under standard temperature conditions, i.e., without the coating being heated. Alternatively the mixtures of the invention can be used to produce coatings which, following application, are dried and cured at an elevated temperature, e.g., at 40-250°C, preferably 40-150°C, and more particularly at 40 to 100°C. This is limited by the thermal stability of the substrate.

Additionally disclosed is a method of coating substrates which involves applying the coating composition of the invention or paint formulations comprising it, optionally admixed with thermally curable resins, to the substrate, drying it, and then curing it with electron beams or UV expo- sure under an oxygen-containing atmosphere or, preferably, under inert gas, optionally at temperatures up to the level of the drying temperature.

If a plurality of layers of the coating material are applied one on top of another, drying and/or radiation curing may optionally take place after each coating operation.

Examples of suitable radiation sources for the radiation cure are low-pressure, medium- pressure, and high-pressure mercury lamps, and also fluorescent tubes, pulsed lamps, metal halide lamps, electronic flash devices, which allow radiation curing without a photoinitiator, or excimer lamps. The radiation cure is accomplished by exposure to high-energy radiation, i.e., UV radiation or daylight, preferably light emitted in the wavelength range of λ=200 to 700 nm, more preferably λ=200 to 500 nm, and very preferably λ=250 to 400 nm, or by irradiation with high-energy electrons (electron radiation; 150 to 300 keV). Examples of radiation sources used include high-pressure mercury vapor lamps, lasers, pulsed lamps (flash light), halogen lamps or excimer lamps. The radiation dose typically sufficient for crosslinking in the case of UV curing is situated in the range from 80 to 3000 mJ/cm².

It will be appreciated that it is also possible to use two or more radiation sources for the cure, two to four for example. These sources may also each emit in different wavelength ranges.

Drying and/or thermal treatment may also take place, in addition to or instead of the thermal treatment, by means of NIR radiation, which here refers to electromagnetic radiation in the wavelength range from 760 nm to 2.5 μηη, preferably from 900 to 1500 nm.

Irradiation can optionally also be carried out in the absence of oxygen, such as under an inert gas atmosphere. Suitable inert gases are preferably nitrogen, noble gases, carbon dioxide, or combustion gases. Furthermore, irradiation may take place with the coating composition being covered with transparent media. Examples of transparent media are polymeric films, glass or liquids, water for example. Particular preference is given to irradiation in the manner described in DE-A1 199 57 900.

It is an advantage of the components and coating compositions of the present invention that, coatings are obtained which combine a high level of flexibility with good resistance. Furthermore, components of formula (I) are more active than those according to J. Mater. Sci. Med (2012), 23: 1 149-1 155. The examples given below are intended to illustrate the invention, but without imposing any restriction on it.

The % and ppm figures given in this specification refer to % by weight and ppm by weight, unless indicated otherwise.

Examples Glycidylether 1

Isosorbid diglycidylether was prepared in an analogous matter to the method of Polymer 52 (201 1 ), 3612 by reaction of 4 mol isosorbid with 40 mol epichlorohydrin. The mixture was heated to 1 15°C to reflux under nitrogen. An aqueous solution of 8 mol sodium hydroxide was con- tinuosly added over 4 hours. Afterwards, water and unreacted epichlorohydrin was distilled off in vacuo. The resulting viscous product isosorbid diglycidylether has a weight per epoxy (WPE) of 235 g/eq.

The product thus obtained consists mainly of isosorbid diglycidylether with minor amounts of the component of two isosorbid molecules, coupled together via a 2-hydroxy-1 ,3-propylene link, bearing two diglycidylether groups, and traces of the component of two isosorbid molecules, coupled together via 2-hydroxy-1 ,3-propylene link, bearing one diglycidylether group and one hydroxy group of an isosorbid moiety remaining free.

Example 1 (Diacrylate of Isosorbid diglycidylether, "ISDGE-DA")

107 parts of Glycidylether 1 , 33 parts acrylic acid, 0,1 parts phenothiazine, 0,6 parts hydrochi- none monomethylether and 3.5 parts triphenylphosphin were mixed at room temperature and reacted at 100 °C for 6 hours. The reaction mixture was cooled down when the acid number dropped to 3mg KOH/g.

According to NMR analysis the epoxy groups vanished completely and acrylic double bonds appeared (signals at 5.85 ppm, 6.15 ppm, und 6.45 ppm). A clear yellowish product was ob- tained.

Example 2

A formulation was prepared by blending 80 parts of the product of Example 1 , 20 parts butyl acetate and 3.2 parts of the photoinitiator Irgacure® 500 (BASF SE, Ludwigshafen, 1 :1 mixture by weight of 2-hydroxy-2-methyl-1 -phenylpropan-1 -one and benzophenone). The resultant varnish formulations were applied to Bonder panel using a 100 μηη box-type coating bar, dried for 1 hour at 60 °C, and were exposed in an IST-UV belt unit at 1350 mJ/cm² under air in each case. The glass transition temperature of the thus obtained coating was determined to 54 °C (measured by DSC, heating rate 10 K/min).

Example 3

A formulation was prepared by blending 70 parts of the product of Example 1 , 30 parts dipro- pylenglycol diacrylate and 4 parts of the photoinitiator Irgacure® 500 (BASF SE, Ludwigshafen, 1 :1 mixture by weight of 2-hydroxy-2-methyl-1 -phenylpropan-1 -one and benzophenone). The resultant varnish formulation was applied to Bonder panel using a 100 μηη box-type coating bar, dried for 1 hour at 60 °C, and were exposed in an IST-UV belt unit at 1350 mJ/cm² under air in each case.

The thus obtained coating exhibited a pendulum damping of 161 seconds (according to DIN 53157, high values represent a high hardness) and an Erichsen cupping of 2.8 mm (according to DIN 53156, high values represent a high flexibility).

Comparative Example 3

A formulation was prepared by blending 70 parts of the diacrylate of bisphenol A diglycidylether diacrylate ("BADGE-DA ", obtained by reaction of Epikote® 828 (diglycidyl ether of bisphenol A, epoxy equivalent weight (EEW) 186 g/eq, Hexion Specialty Chemicals B.V., Hoogvliet, The Netherlands) and 2 equivalents acrylic acid), 30 parts dipropylenglycol diacrylate and 4 parts of the photoinitiator Irgacure® 500 (BASF SE, Ludwigshafen, 1 :1 mixture by weight of 2-hydroxy- 2-methyl-1 -phenylpropan-1 -one and benzophenone). The resultant varnish formulation was applied to Bonder panel using a 100 μηη box-type coating bar, dried for 1 hour at 60 °C, and were exposed in an IST-UV belt unit at 1350 mJ/cm² under air in each case.

The thus obtained coating exhibited a pendulum damping of 203 seconds and an Erichsen cupping of 1.6 mm.

Comparative Example 4 (Dimethacrylate of Isosorbid diglycidylether, "ISDGE-DMA")

107 parts of Glycidylether 1_, 41 parts methacrylic acid, 0,1 parts phenothiazine, 0,6 parts hydro- chinone monomethylether and 3.5 parts triphenylphosphin were mixed at room temperature and reacted at 100 °C for 6 hours. The reaction mixture was cooled down when the acid number dropped to 4 mg KOH/g.

According to NMR analysis the epoxy groups vanished completely. The resulting dimethacrylate is a clear yellowish product. A formulation was prepared by blending 70 parts of this dimethacrylate, 30 parts dipropylenglycol diacrylate and 4 parts of the photoinitiator Irgacure® 500 (BASF SE, Ludwigshafen, 1 :1 mixture by weight of 2-hydroxy-2-methyl-1 -phenylpropan-1 -one and benzophenone). Comparative Example 5: (comparison to BADGEDA and ISDGE-dimethacrylate)

The resultant varnish formulations of Example 3, Comparative Example 3 and Comparative Example 4 were applied to Bonder panels, using a 100 μηη box-type coating bar and black glass plates, using a 50 μηη box-type coating bar, respectively, dried for 1 hour at room temperature, and were exposed in an IST-UV belt unit at 1350 mJ/cm² under air in each case.

The thus obtained coatings were evaluated according to Koenig pendulum damping (according to DIN 53157, high values represent a high hardness), an Erichsen cupping test (according to DIN 53156, high values represent a high flexibility), and an ScotchBrite scratch test (10 double rubs with a ScotchBrite fleece under 500g weight; gloss was measured at 60° before and after scratching; the higher the gloss retention the better). The results are shown in table 1.

Table 1 :

Exposed under identical conditions, the data show, that all coating films are sufficiently hard (> 170 s pendulum hardness), however, considerable scratch resistance is only seen with ISDGE- DA and BADGE-DA, and good flexibility (Erichsen cupping > 2mm) is only obtained with ISDGE-DA. Thus, within the series of experiments, the results of which are shown in table 1 , the experiment based on example 3 (according to the invention) clearly shows superior effects compared with the experiments based on comparative examples 3 and 4.

Comparative Example 6: (Acrylates of Isosorbid diglycidylether and bisphenol A diglycidylether with comparable epoxy equivalent weights)

Three formulations based on different epoxy acrylates were compared: a) Diarcylate based on Isosorbid diglycidylether with an EEW 235 g/eq (inventive)

b) Diacrylate based on bisphenol A diglycidylether diacrylate with an EEW 241 g/eq and c) Diacrylate based on bisphenol A diglycidylether diacrylate with an EEW 186 g/eq (comparative example 3) a) A formulation was prepared by blending 70 parts of the product of Example 1 , 30 parts dipro- pylenglycol diacrylate and 4 parts of the photoinitiator Irgacure® 500 (BASF SE, Ludwigshafen, 1 :1 mixture by weight of 2-hydroxy-2-methyl-1 -phenylpropan-1 -one and benzophenone). b) A formulation was prepared by blending 70 parts of of the reaction product of standard Bi- sphenol-A-diglycidylether (EEW 241 g/eq) with acrylic acid, 30 parts dipropylenglycol diacrylate and 4 parts of the photoinitiator Irgacure® 500 (BASF SE, Ludwigshafen, 1 :1 mixture by weight of 2-hydroxy-2-methyl-1 -phenylpropan-1 -one and benzophenone). c) A formulation was prepared by blending 70 parts of the reaction product of standard Bis- phenol-A-diglycidylether (EEW 186 g/eq) with acrylic acid, 30 parts dipropylenglycol diacrylate and 4 parts of the photoinitiator Irgacure® 500 (BASF SE, Ludwigshafen, 1 :1 mixture by weight of 2-hydroxy-2-methyl-1 -phenylpropan-1 -one and benzophenone).

The resultant varnish formulations were applied to Bonder panel using a 100 μηη box-type coating bar, dried for 1 hour at 60 °C, and were exposed in an IST-UV belt unit at 1350 mJ/cm² un- der air in each case. The results are shown in table 2.

Table 2:

The inventive ISDGE-DA (formulation a)) is at high enough hardness and comparable scratch resistance more flexible than the comparative epoxy acrylates based on Bisphenole A chemistry.

Claims

25

Claims

1 . Radiation curable diacrylate of formula (I),

Mixture of radiation curable diacrylate of formula (I) according to Claim 1 , comprising 40 to 90 wt% of a component of formula (I) wherein R¹ = acryloyl, R² = hydrogen, R³ = hydrogen, R⁴ = acryloyl,

4 to 25 wt% of a component of formula (I) wherein R¹ = acryloyl, R² = hydrogen, R³ = acryloyl, R⁴ = hydrogen

4 to 25 wt% of a component of formula (I) wherein R¹ = hydrogen, R² = acryloyl, R³ = hydrogen, R⁴ = acryloyl and

2 to 10 wt% of a component of formula (I) wherein R¹ = hydrogen, R² = acryloyl, R³ = acryloyl, R⁴ = hydrogen, with the proviso that the sum always adds up to 100 % by weight.

Mixtures of components according to Claim 1 or 2 with components of formula (Ic)

wherein

the radicals R¹, R², R³, and R⁴ are defined as above,

R^a is hydrogen or a radical -CH₂-CHOR^b-CH₂OR^c,

wherein one radical out of R^b and R^c is acryloyl, and the other is hydrogen. 26

4. Radiation-curable coating compositions comprising

(A) at least one compound of formula (I), as defined in Claims 1 , 2 or 3, and mixtures thereof,

Process for the preparation of components of formula (I) as defined in Claims 1 , 2 or 3, wherein the corresponding glycidyl ethers of anhydrosugars are reacted with acrylic acid.

Process according to Claim 5, wherein the glycidyl ether of anhydrosugars exhibits an epoxy equivalent weight of at least 200 g/eq.

Process according to Claim 5 or 6, wherein the anhydrosugar is selected from the group consisting of isosorbide, isomannide, and isoidide.

The use of components according to Claim 1 , mixtures according to Claims 2 or 3 or coating compositions according to Claim 4 in coating compositions.

The use of components according to Claim 1 , mixtures according to Claims 2 or 3 or coating compositions according to Claim 4 in printing inks for flexographic, screenprinting, lithographic, letterpress, gravure or ink-jet printing or in overprint varnishes.

10. The use of components according to Claim 1 , mixtures according to Claims 2 or 3 or coating compositions according to Claim 4 in radiation curable adhesives and in manufacturing processes of optical fibers or printed circuit board.