DD283825A5 - PROCESS FOR PREPARING PHOTOINITIATOR COPOLYMERS - Google Patents

Abstract

The invention relates to a process for the preparation of photoinitiator copolymers and to their use as photoinitiators in the photopolymerization of ethylenically unsaturated compounds or systems containing such. {Photoinitiator copolymers; unsaturated photoinitiator monomers; ethylenically unsaturated monomers; photopolymerization}

Description

FIELD OF THE INVENTION

The invention relates to photoinitiator copolymers which are composed of at least two different monomer units, of which at least one carries a photo-initiating structural unit. Such polymer compounds serve

as radical-forming photoinitiators for the photopolymerization of ethylenically unsaturated compounds or systems containing them. Photoinitiator copolymers show a number of unexpected advantages over conventional monomeric or derived homopolymeric photoinitiators.

Photochemically induced polymerization reactions have become very important in the art, especially when it comes to rapid curing of thin layers, such as e.g. in the curing of lacquer coatings and Kunststoffbe-layers on paper, wood, metal and plastic or in the drying of printing inks. Radiation curing in the presence of photoinitiators is distinguished from conventional methods for drying or curing coatings. Raw material and energy savings, low thermal load on the substrate, and in particular a high speed. However, the preparation of polymer materials per se by polymerization of corresponding unsaturated monomeric starting materials is often carried out photochemically and with the aid of photoinitiators, conventional methods such as solution and emulsion polymerizations are used.

f Q?

Furthermore, photoinitiators are often used in photopolymerizable compositions for photolithographic processes, such as in particular in negative photoresists in semiconductor electronics and optoelectronics, b use.

Since in the reactions mentioned none of the reactants is able to absorb the photochemically active radiation sufficiently, photoinitiators must be added which are able to absorb either radiated high-energy radiation, usually UV light, and while active starter

form radical, which in turn trigger the photopolymerization, or to transfer the absorbed energy for radical formation on one of the polymerizable reactants. The initiators normally do not participate in the actual polymerization reaction. CHARACTERISTICS OF THE KNOWN PRIOR ART

Suitable photoinitiators for this purpose are predominantly compounds of the aromatic ketone type, such as benzophenones, benzoin ethers, benzil monoketals, dialkoxyacetophenones, thioxanthones, bisacylphosphine oxides or hydroxyalkylphenones, and derivatives derived from these structural types. Particularly advantageous are hydroxyalkylphenone photoinitiators, as described in the patents DE-PS 27 22 264 and EP-PS 3002, proven, mainly because of their high reactivity, but also because of the excellent dark storage stability of the offset with them radiation-curable systems and the slight tendency of the layers hardened with it to yellow.

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The progressive diversification and specialization of processes and products in the field of coating technology with polymer materials and the increasingly associated requirement of tailor-made sample solutions mean that ever higher and more specific requirements are placed on photoinitiators as well. Photoinitiators of a conventional type are therefore often failing, or at least not optimally, to meet the demands made of them today. "It is increasingly the case that photoinitiators should still be able to do more than merely formulate photopolymerization or photocrosslinking radicals. Essential problem areas here are, for example, the compatibility in a wide variety of systems, in particular those which also contain non-photopolymerizable components to achieve certain material properties (so-called hybrid systems) and furthermore the migration-resistant incorporation of photoinitiator or its photolysis products into the photopolymerized end product. At the same time, the additional equity

the photoreactivity of the initiator is unaffected; A high dark storage stability of the systems provided therewith is likewise of great importance for practical usability. Further developments in these directions have already been carried out, primarily on the basis of the photoreactivity of particularly high-performance hydroxyalkylphenone photoinitiators. Thus, for example, the photoinitiators described in DE-OS 35 12 179 are particularly suitable for use in aqueous systems. The unsaturated functionalized photoinitiators from DE-OS 35 34 645 and EP-OS 161463 and the particularly versatile coreactive photoinitiators of German Patent Applications P 37 07 891 and P 37 38 567 allow the

^ QG 4 0 ^ 88

migration-resistant incorporation into the product by photochemical and non-photochemically induced co-reaction with a variety of system components, with itself or with the substrate before, during or even after the actual photopolymerization.

However, these promising developments are still in many ways in need of improvement. Thus, in the modified photochemicals of the cited documents cited above, it is predominantly always possible to implement only individual specific additional properties. Therefore, a variety of appropriately modified photoinitiators must be synthesized and prepared from the ground up for the most diverse requirements and purposes, which requires a lot of effort and therefore is not very economical

OBJECT OF THE INVENTION

The invention was therefore based on the problem to find and provide powerful photoinitiators with which can be realized on the one hand a variety custom-made additional properties and on the other hand are easily accessible, for example starting from a few universally applicable basic building blocks.

DISCLOSURE OF THE INVENTION OF THE INVENTION

It has now been found that these requirements are fulfilled in excellent Wej.se of photoinitiator copolymers having molecular weights between 500 and 1,000,000, obtainable by copolymerization of at least two different monomer units of the formulas I and II in the ratio I / II = 1-100

fa,·?

(D

CH ₂ =

IN

(II)

CH ₂ = C-

where is meant

R ^a , R are each, independently of one another, H, Cl, CN, C 1 -C 4 -alkyl or phenyl,

CO-, COO-, 0-C0-, (CH ₉₎ Y, COO (CH) Y,

£ * H £ mxl

CO (OCH ₉ CH ₉ ) Y with η = 1-10 and Y a

£ * £ » IX

a single bond, -O-, -S-, -CO-, -COO-, -OCO-, -NH-, -1

IN

eixie of the photoinitiator basic structures

W -c-

C-R or

wherein

0 R -CR ³ R ⁴ R ⁵ or -P (R ⁶ ) _2>

W9.

and

R ¹ , R ^{2 is} H, halogen, C _1-12 -alkyl or

3 4 R, R are each independently

H, C _1-12 -alkyl] CyI, C ₁ _ ₁₂ alkenyl, C, ρ-alkoxy or together are C ₂ _ ₆ alkylene,

-OH, C _1-6 -alkoxy, C-, -alkanoyloxy, -N (C _1-6 -alkyl) ₂ ,

/ "" \ 7 7 -N Ο, * -SO ₀ R, -OSO ₀ R,

RC, alkyl, C _1-6 alkanoyl, phenyl or benzoyl, each optionally with halogen, C ₁ , alkyl or C _n , alkoxy

^J 1-6 1-6

substituted

R ^{7 is} C _1-6 alkyl, phenyl. represents,

A is one of the photoinitiator primitives IN

with the meanings given above, or H, C _1-12 -alkyl, C _1-12 -alkenyl, ι phenyl,

Styryl, halogen, NCO, NCS, N ₃ , SO ₃ H, SO ₂ Cl

CR ^C = CR ^d R ^e or CR ^ CR ^d R ^e with R ^C ,

R ^d , R ^{e are} each H or CH ₃ , SiR ^f R ^g R ^h with ^fgh

R ^f , R ^g , R ^{h are} each Cl,

Alkoxy, alkanoyloxy.

PAT LOG 4 090588

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The copolymers according to the invention are high-performance, individually structurable photoinitiators for the photopolymerization or photocrosslinking of ethylenically unsaturated compounds or systems containing them. However, they can also be used as photoinitiating and layer-forming components in steel-hardening systems.

The invention thus provides photoinitiator copolymers having molecular weights of between 500 and 1,000,000, obtainable by copolymerization of monomer units of formulas I and II defined above in the ratio I / II = 1-100.

The invention further provides the use of these photoinitiator copolymers as photoinitiators for the photopolymerization of ethylenically unsaturated compounds or systems containing them.

The invention further relates to a process for the preparation of photopolymerizable ethylenically unsaturated compounds containing systems, wherein the au polymerizing mixture of at least one of these photoinitiator copolymers added.

The invention finally polymerizable systems containing at least one ethylenically unsaturated photopolymerizable compound and optionally further known and customary additives containing at least one of these photoinitiator copolymers.

The photoinitiator copolymers according to the invention are new. They turn out to be highly-reactive photoinitiators whose specific properties can be adjusted and varied by the quantitative and qualitative choice of the monomer units I and II. They are very simple

thermal copolymerization of the corresponding monomer units accessible. Due to their polymeric character, they have a high migration fcionsfestigkeit in the photopolymerizable system or in the photocommerized end product.

Diq photoinitiator copolymers of the invention are composed of at least two different monomer units of the formulas I and II.

1,

Monomer unit I contains a polymerizable ethylenically unsaturated structural part, in which the radical R ^{a is} hydrogen, chlorine, cyano, a C ₁ , .- alkyl or a

'a

Represent phenyl group. Preferably, R is hydrogen and thus the unsaturated structural part is a vinylic group. This unsaturated structural part is linked either directly via a single bond or via a bridging group X with any desired photoinitiator structure IN, as in principle also exists in conventional photoinitiators.

The bridging group X may be a carbonyl, a carboxyl or an alkylene group having 1-10 C atoms. It may also be a carbonyloxyalkylene or a carbonylpolyoxyethylene group each having 1-10 methylene or oxyethylene units. The linkage with the photoinitiator basic structure IN can be effected by a single bond, by an oxygen, sulfur, carbonyl, carboxyl or amino group. Preferred linkages of unsaturated moiety with photoinitiator structure IN are the single bond, the carbonyl, the carbonyloxymethyleneoxy and the carbonyloxyethoxy groups. In the case of linking by single bond, vinyl-substituted derivatives of conventional photoinitiators result. In the other cases of preferred linkages, acrylated photoinitiator derivatives result.

PAT LOG 4 090588

IN is essentially the aromatic ketone structural unit or the thioxanthone structural unit

-C-R or

however, as present in most of the classical photoinitiators, it may also mean any other structures with photoinitiator properties.

3 4 5 If R stands for the grouping -CR RR, the result is

According to the definitions given above for R, R and R, the photoinitiator bases of the acyloin ethers, the dialkoxyacetophenones, the hydroxyalkylphenones and aminoalkylphenones and also the cr-sulfonyl ketones.

Copolymerizable hydroxyalkylphenone derivatives are particularly preferred monomer units of the formula I.

When R is the group -P (R) ₂ , the resulting photoinitiators belong to the class of acyl phosphine oxides.

Copolymerizable thioxanthone derivatives are also preferred monomer units of the formula I.

PAT LOG 4 090588

Numerous unsaturated derivatives of various photoinitiator groups, as represented by formula I, are known and in part also commercially available. This applies in particular to the hydroxyalkylphenone derivatives described in DE-OS 35 34 and EP-OS 161463 and the corresponding unsaturated functionalized photoinitiators of German Patent Applications P 37 07 891 and P 37 38 567. They can be prepared in principle by standard methods of organic chemistry.

The reaction conditions here can be taken from the standard works of preparative organic chemistry, e.g. HOUBEN-WEYL, Methods of Organic Chemistry, Georg-Thienui Verlag, Stuttgart, or ORGANIC SYNTHESIS, J. Wiley, New York London Sydney.

In general, it is favorable to prepare the comonomers of the formula I or corresponding precursors according to the established synthesis methods which are common for the underlying photoinitiators. In this case, it is advantageous to start from the known photoinitiators as starting substances and to link them to the unsaturated structural unit in common reactions, such as substitution reactions, in one or more steps. However, it is also possible to use already suitably substituted precursors of the known photoinitiators and to generate the actual photoinitiator active structure in them only when the unsaturated structural part is already present.

Particularly suitable as precursors for unsaturated functionalized photoinitiators are many of the photoinitiator derivatives described in the German Patent Applications P 37 07 891 and P 37 38 567, which carry reactive substituents having functional groups.

pat log 4

- II -

Of these, preference is given to the hydroxyethoxy- and hydroxyethylthio-substituted photoinitiator derivatives, since these can be easily converted into the corresponding (meth) acrylic esters. Typical unsaturated functionalized photoinitiator derivatives which can serve as monomer building blocks of the formula I for the photoinitiator copolymers of the invention are, for example

(4-Vinylphenyl) -2-hydroxyrr-2-propyl ketone (Ia)

(4-Allyloxyphenyl) -2-hydroxy-2-propyl ketone (Ib)

[4- (2-Allyloxyethoxy) phenyl] -2-hydroxy-2-propyl ketone (Ic) 4- (2-Hydroxy-2-methyl-propionyl) -phenoxyacetic acid vinyl ester * (Id)

(4-Acryloyloxyphenyl) -2-hydroxy-2-propyl ketone (Ie)

(4-Methacryloyloxyphenyl) -2-hydroxy-2-propyl ketone (If)

[4- (2-acryloyloxyethoxy) -phenyl] -2-hydroxy-2-

propyl ketone (Ig) [4- (2-methacryloyloxyethoxy) phenyl] -2-hydroxy-2-

propyl ketone (Ih) [4- (2-acryloyloxy-diethoxy) -phenyl] -2-hydroxy-2-

propyl ketone (Ii) [4- (2-acryloyloxyethyl) thiophenyl] -2-hydroxy-2-

propyl ketone (Ij) [4- (2-acryloyloxyethylthio) phenyl] -2- (N-morpholino) -

2-propyl ketone (Ik)

2- [2- (acryloyloxy) ethylthio] thioxanthone (II)

2- [2- (acryloylamino) ethylthio] thioxanthone (Im)

2- [2- (Allyloxy) ethylthio] thioxanthone (In)

2- [2- (Allylamino) ethylthio] thioxanthone (Io)

4- [2- (methacryloyloxy) ethoxycarbonyl] thioxanthone (Ip)

- 12 -

The monomer unit of the formula II is constructed completely analogously to the monomer unit of the formula I. The group A linked herein to the unsaturated moiety directly or via the bridging moiety X may be a photoinitiator basic structure IN as defined above, but may also be hydrogen, C _1-6 alkyl, phenyl, in particular chlorine and fluorine, the isocyanate , Isothiocyanat-, azide, sulfonic acid, sulfonyl chloride, a vinyl or oxiranyl group, which may optionally be mono- or polysubstituted by chlorine or methyl or a silyl group in which the silicon-bonded radicals chlorine and / or carbonyl ₁₂ ~ alkyl and / or C _1-12 alkoxy and / or C, ^ alkanoyloxy.

Unsaturated monomer units of the formula II which contain no photoinitiation structural constituents IN are known and available in great diversity from the field of polymer chemistry. These are predominantly vinyl and acrylic derivatives, that is to say customary monounsaturated and easily accessible unsaturated monomer building blocks.

Preferred such monomer building blocks are in particular those which have functional groups capable of further reactions, in particular hydroxy, carboxy, carboxamide, sulfonic acid, isocyanate, olefinically unsaturated and silyl groups. Through such functionalized monomer building photoinitiator copolymers according to the invention can be prepared with specific properties tailored to the particular application

Ρ-Αψ W

- 13 -

become. Thus, compatibility can be achieved with a wide variety of radiation-curable systems and in particular also with hybrid binder systems. The functional groups enable the photoinitiator copolymers according to the invention to coreactivity in the sense of P 37 07 891 / P 37 38 567, i. that is, in particular to reactions with constituents of the radiation-curable systems or with the substrate.

Typical such monomer units of the formula II are, for example, (meth) acrylic acid, (meth) acrylamide, (meth) acrylic acid alkyl esters, hydroxyethyl methacrylate, (meth) acrylic acid

Alkenyl or epoxyester, hexanediol diacrylate, acrylonitrile, styrene, divinylbenzene, methyl vinyl ketone, N-vinyl pyrrolidone, 2- (N, N-dimethylamino) ethyl methacrylate, 3- (trimethoxysilyl) propyl methacrylate.

In the case of monomeric units of the formula II containing initiator groups, preference is likewise given to those which are given as being preferred for the monomer units of the formula I. If the photoinitiator copolymers according to the invention are each formed only from monomers containing initiators, then the monomer units of the formula I and of the formula II are different from one another.

The preparation of the photoinitiator copolymers according to the invention from the monomer units of the formulas I and II is carried out in a manner known per se for the polymerization of such olefinically unsaturated compounds, namely in solution with the aid of conventional thermally activatable radical initiators, such as benzoyl peroxide or azobisisobutyronitrile with the exclusion of exposure to light. The monomer units of the formulas I and II are used quantitatively so that the ratio of I to II

PAT LOG 4 090588

- 14 -

between 1 and 100, preferably between 2 and 10. Typical solvents for the polymerization are about tetrahydrofuran and toluene. The reaction is usually carried out at the reflux temperature of the solvent. The isolation of the photoinitiator copolymers is carried out by precipitation with a non-solvent, for example η-hexane. Repeated reprecipitation may result in the photoinitiator copolymers being purified. As is customary for polymer products, the products obtained can be sufficiently characterized by their average molecular weight Mw, which can be determined by gel permeation chromatography, and their Tg, which can be determined by differential thermoanalytically determinable glass transition. A statistical distribution of the different monomer units in the copolymer is assumed. The average molecular weight may be between 500 and 1,000,000 and is preferably between 1,000 and 10,000.

The photoinitiator copolymers according to the invention can be used very advantageously as photoinitiators equipped with tailored additional properties for the photopolymerization of ethylenically unsaturated compounds or systems containing them. Primarily, they serve as UV curing agents for coating or polymer coatings, UV-curable binder and hybrid binder systems, printing inks and for radiation curing of aqueous prepolymer dispersions analogously to conventional photoinitiators. The application is carried out in a customary manner, wherein they are added to the systems to be polymerized usually in amounts of 0.1-20 wt.%, Preferably 0.5-12 wt.%. This addition is usually done by simply stirring in the systems to be polymerized.

- 15 -

The photoinitiator copolymers according to the invention can in many cases themselves also be taken as the sole or as an essential constituent of radiation-curable systems. They then take over both the layer-forming and the photo-initiating function at the same time.

Thus, for example, copolymers of [4- (2-acryloyloxyethoxy) phenyl] -2-hydroxy-2-propyl ketone (Ig) with 2-dimethylaminoethyl methacrylate or 3- (trimethoxysilyl) -propyl methacrylate may be coated on a substrate, preferably with UV Photostructuring radiation. These materials are thus well used as negative photoresists.

With the aid of the photoinitiator copolymers according to the invention, it is also possible to make photoreactive polymer materials which themselves are not crosslinkable or photo-structurable because they contain, for example, no ethylenically unsaturated double bonds.

It is known that the effect of numerous conventional photoinitiators in a mixture with differently structured photoinitiators, that is, coinitiators and / or sensitizers, in particular organic amines, can in some cases be considerably increased. Typical of these are, for example, mixtures of hydroxyalkylphenones with thioxanthones and optionally amino compounds, such as N-methyldiethanolamine.

The combination of initiators with coinitiators or sensitizers in the photoinitiator copolymers of the invention is a particularly preferred aspect of the invention. It has surprisingly been found that such photoinitiator copolymers are more effective than mixtures of the underlying conventional photoinitiators, coinitiators and sensitizers.

WQ 4

- 16 -

For example, copolymers of the unsaturated hydroxyalkylphenone derivative Ig and the unsaturated thioxanthone derivative are surprisingly significantly more effective than the corresponding mixture of conventional hydroxyalkylphenone and thioxanthone photoinitiators. An explanation for this could be seen in an immediate co-initiating interaction of the different initiator groups, due to the fixation in the copolymer dressing. ₍

Fotoiuitiator copolymers can be applied very advantageous as a discrete photoinitiator layer on the substrate material and then only with a photopolymer? Be provided »layer material. The application in the form of such two-layer systems takes place in the sense of DE-OS 36 29 543 and DE-OS 37 02 897. Particularly advantageous in this case are photoinitiator copolymers with polar, optionally chelating groups and with silyl groups. As a result, a better fixation on metal, semiconductor, glass and ceramic substrates is achieved.

Copolymers containing amino-containing monomer units of the formula II, for example with 2- <N, N-dimethylamino) -ethyl methacrylate, contain in themselves the much advantageous Aminbeschnauniger and are more reactive than the corresponding conventional systems.

In such amino-containing Fctoinitiator copolymers can be incorporated during the preparation of dyes that can form salts with amino groups. Suitable examples are xanthene dyes such as rose bengal. Surprisingly, this shifts the absorption

PAT W 1

- 17 -

tion maximum in the longer wavelength range, so that such modified photoinitiator copolymers can be activated with longer-wave radiation, such as between 500 and 600 nm.

In general, the photoinitiator copolymers according to the invention have an excellent migration stability due to their high molecular weight character. This means they do not migrate in or aug _J: the corresponding radiation-curable systems, which is particularly important for many applications.

A system to be polymerized is understood as meaning a mixture of free-radical-initiable mono- polyfunctional ethylenically urgesättigten monomers, oligomers, prepolymers, polymers or mixtures of these oligomers, prepolymers and polymers with unsaturated monomers, which, if necessary or desirable, further additives such , As antioxidants, light stabilizers, dyes, pigments, abr.r may also contain other known photoinitiators and reaction accelerators. Unsaturated compounds are all those whose C = C double bonds by z. As halogen atoms, carbonyl, cyano, carboxy, ester, amide, ether or aryl groups or by conjugated further double or triple bonds are activated. Examples of such compounds are vinyl chloride, Vinylider'.hlorid, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, methyl, ethyl, n- or tert. Butyl, cyclohexyl, 2-ethylhexyl, benzyl, phenyloxyethyl, hydroxyethyl, hydroxypropyl, lower alkoxyethyl, tetrahydrofurfuryl acrylate or methacrylate, vinyl acetate, propionate, acrylate, succinate, N-vinylpyrrolidone,

PAT LOG 4 090588

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N-vinylcarbazole, styrene, divinylbenzene, substituted styrenes, as well as the mixtures of such unsaturated compounds. Polyunsaturated compounds such as, for example, ethylene diacrylate, 1,6-hexanediol diacrylate, propoxylated bisphenol A diacrylate and dimethacrylate, trimethylolpropane diacrylate and pentaerythritol triacrylate can also be polymerized with the photoinitiators used according to the invention. Other suitable photopolymerizable compounds are unsaturated oligomers, prepolymers or polymers and mixtures thereof with unsaturated monomers. These include, for example, unsaturated polyesters, unsaturated acrylic materials,

Epoxies, urethanes, silicones, aminopolyamide resins and in particular acrylated resins such as acrylated silicone oil, acrylated polyesters, acrylated urethanes, acrylated polyamides, acrylated soybean oil, acrylated epoxy resin, acrylated acrylic resin, suitably admixed with one or more acrylates of a mono-, di- or polyalcohols.

The term "photopolymerization of ethylenically unsaturated compounds" is to be understood in the broadest sense. Including z. As well as the further polymerization or crosslinking of polymeric materials, such as "of prepolymers, homo-, co- and terpolymerization of simple monomers and also the combination of the reaction types mentioned.

By the action of high-energy radiation, preferably UV light, to which the photoinitiator copolymers of the invention containing photopolymerizable systems, the photopolymerization can be triggered.

PAT LOG 4 090588

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The photopolymerization is carried out by methods known per se by irradiation with light or UV radiation of the wavelength range of 250-500 nm, preferably of 300-400 nm. As radiation sources, sunlight or artificial radiators can be used. For example, mercury vapor high pressure, medium pressure or low pressure lamps as well as xenon and tungsten lamps are advantageous.

The carrying out of the photopolymerization using the photoinitiator copolymers according to the invention can be carried out either batchwise or continuously. The irradiation time depends on the type of implementation, on the type and amount of the polymerizable materials used, on the type and concentration of the photoinitiators used and on the intensity of the light source and can, for example in the radiation curing of coatings, in the range of a few seconds to minutes , in large batches, such as in bulk polymerization, but also in the hour range.

The photoinitiator copolymers according to the invention are preferably used as photoinitiators in the UV curing of thin layers such as lacquer coatings on all materials and supports customary for this purpose. These can primarily be paper, wood, textile carriers, plastic and metal. An important field of application is also the drying or curing of printing inks and screen printing materials, the latter of which are preferably used in the surface coating or design of, for example, cans, tubes and metal caps. Due to the substantial absence of free initiator residues or free photolysis products in the photoinitiator copolymer according to the invention.

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After photopolymerization, these systems are particularly suitable in application areas where diffusion of such residues into corresponding end products is to be excluded, for example when packaging materials provided with photopolymerized coatings come into contact with foodstuffs.

EMBODIMENTS

A. Preparation of photoinitiator copolymers

General manufacturing instructions:

The monomeric starting materials are dissolved in the appropriate molar amounts in THF (150-300 ml / batch up to 100 mmol) and mixed with azobisisobutyronitrile (150-300 mg / batch up to 100 mmol).

It is heated under reflux for 12 hours. Thereafter, the solvent is stripped off, the residue taken up in ethyl acetate, the solution is treated with activated charcoal and filtered. By precipitation with η-hexane and dropping from Essigejster / n-hexane to obtain the photoinitiator copolymer.

Used photoinitiator monomers:

[4- (2-acryloyloxyethoxy) phenyl] -2-hydroxy-2-propyl-ketone (Ig)

[4- (2-methacryloyloxyethoxy) phenyl] -2-hydroxy-2-propyl ketone (Ih)

[4- (2-acryloyloxyethylthio) phenyl] -2- (N-morpholino) -2-propyl ketone (Ik)

2- [2- (Acryloyloxy) ethylthio] thioxanthone (II) 4- [2- (Methacryloyloxy) ethoxycarbonyl] thioxanthone (Ip)

PAT LOG 4 090588

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Prepared Photoinitator Copolymers:

Example monomers / no.

molar Mw Mengenantei1

Ik 10 ip 1 acrylic acid 2 Ik 10 ip 1 acrylic acid 5

3000th

Tg ( ⁰ C)

1 . ig 10 3000 37.7 Il 1 2 ig 1 3200 47.4 Il 1 3 Ik 5 '1900 47.9 Il 1 4 Ik 10 1900 40.8 Il 1 5 Ik 15 1950 38.5 Il 1 6 Ik 10 4100 ip 1

32.7

3050

35.3

w f

- 22 -

Example no. monomers / molar proportion mw Tg (° C) 9 * 2-Dime tin flam 3 ino- 1 3450 36 , 5

16

ethy.lmethacrylat

Rose Bengal (0.5 g / 100 mmol

10 10 methyl methacrylate b 1 2200 107 11 Ih methyl methacrylate 1 1 '2300 90.2 15 12 ig n-dodecyl acrylate 10 1 3400 28.3 20 13 ig acrylic acid 5 1 3300 35.9 14 ig acrylamide 10 1 3000 45.3 25 15 ig acrylamide 1 1 2300 62.9

Ig

3- (trimethoxysilyl) propyl methacrylate)

3100 (oil)

Ig

3- (trimethoxysilyl) propyl methacrylate)

3100

(oil)

* Maximum absorption at λ = 550 run

PAT LOG 4 090588

- 23 B. Application-specific comparative experiments

In samples of a pigmented radiation-curable binder system consisting of

75 parts by weight of polyester acrylate (Laromer® EA 81, BASF)

25 parts by weight of hexanediol diacrylate 30 parts by weight of TiO- "

the photoinitiator copolymers of the invention to be tested and corresponding conventional photoinitiators or photoinitiator mixtures were stirred in for comparison.

The initiator-containing systems were on glass plates. (10 x 10 cm) applied in a layer thickness of 24 microns.

The UV curing was then carried out by passing the coated plates on a conveyor belt of variable speed under Hg medium pressure lamps (lamp power 2 × 80 W / cm, lamp spacing 10 cm).

As a measure of the respective curing result at different belt speeds, the pendulum hardness according to König (DIN 53157) was determined after storage for 20 hours.

PAT LOG 4 090588

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Pendulum hardness (seconds)

Belt speed (m / min) 5 10 15 20

Initiator / content

Bspl.-Nr. 1/3 wt.% Bspl.-No. 2/3 wt.%

Comparison + / 3% by weight

124 133

.92

83 95

71 81

58 62

53 41

additionally in all cases 2% by weight of N-methyldiethanolamine

+ Mixture of phenyl-2-hydroxy-2-propyl ketone and

2-isopropylthioxanthone / 9: 1 (Darocur 1664, E. Merck) C. Application examples / photostructuring

A 10% solution of the copolymer according to Bspl.-Nr. 9 in diethylene glycol dimethyl ether was spin-coated on a glass plate (5x5 cm) (30 sec., 4500 rpm). The coated plate was dried at 150 ^° C. for 10 minutes. The half-covered plate was irradiated for 4 minutes with a UV lamp (type TQ 180, Fa. Heraeus Original Hanau) at a distance of 5 cm. After irradiation, acetone was treated with the unexposed portion of the coating peeling off. In the exposed area remained a well-adherent, unchanged even in prolonged storage in acetone, cured coating of 0.4 pm thickness.

PftT LQQ 4 09,0,58J

2 0 3 825

- 25 -

An analogous result was achieved with the copolymer according to Bspl.-Nr. 16th

An analogous result was obtained with a copolymer of monomer Ig, 3- (trimethoxysilyl) propyl methacrylate and methyl methacrylate in a molar ratio of 3: 1: 5.

PAT LOG 4 090588

Claims (4)

1, Process for the preparation of photoinitiator copolymers by copolymerization of different monomer units «, characterized in that at least two different monomer units of the formulas I and II in the ratio I / II = 1-100 R ^a (I) CH ₂ -C- (X) ₀ ^ ₁ IN ^Rb (II) CH ₂ C- (X) _{0 # 1} A where is meant from
Rf R are each independently H, >, l, CN, Alkyl or phenyl, CO, COO, O-C0-, (CH ₂ J _n Y, C 00 (CH ₂ J _n Y, CO (OCH ₂ CH ₂ J _n Y with η = 1-10 and Y denotes a single bond, -O-, -S-, -CO-, -COO-, -OCO-, -NH-, - IN a photoinitiator basic structures C-R or R · ¹ wherein R -CR ³ R ⁴ R ⁵ or -P (R ⁶ ) ₂ , and R, RH, halogen, C _1-12 -alkyl or C _1-12 - R, R are each independently H, C _1-12 alkyl, C _1- ^ -. Alkenyl, oxy or together C _2-6 alkylene, alk -OH, C _1-6 -alkoxy, C _1-6 -alkanoyloxy, alkyl) ₂ , -Ο · -Ο / \ 7 ₇ -NO, -SO ₂ R ', -OSO ₂ R, C _1-6 alkyl, C _1-6 alkanoyl, phenyl or benzoyl, each optionally substituted with halo, 'J _1-6 alkyl or C _1-6 alkoxy C _1-6 alkyl, phenyl represents. -ΜΑ one of the photoinitiator basic structures IN with the meanings given above or H, C ^^ - alkyl, C _1. ^ - alkenyl, phenyl, Styryl, halogen, NCO, NCS, H ₃ , SO ₃ H, SO ₂ Cl, CR ^c = CR ^d R ^e or CR ^C - CR ^d R ^e with R ^c , R ^d , R ^e . each H or CH ₃ , SiR ^f R ^g R ^h with R ^f , R ⁹ , R each Cl, C _{lü <12} alkyl, alkoxy, alkynoyloxy, to the products with molecular weights between 5oo> id 1,000,000 copolymerized. 2 "Photopolymerizable systems containing at least one ethylenically unsaturated photopolymerizable compound and optionally other known and customary additives, characterized in that they additionally contain at least one photoinitiator copolymer prepared by the process according to claim 1 2 8 claims 3. Photopolymerizable systems according to claim 2, characterized in that they contain 0.1 to 20 wt .-% of the photoinitiator copolymer. 4. Use of the photopolymerizable systems according to claim 2 or 3, characterized in that they are used in a process for producing a radiation -ZS- hardened coating on a substrate, wherein this is coated with a photopolymerizable system and the hardening by irradiation with UV light of a wavelength between 250 and 600 nm makes »uses«