DE3126433A1 - Novel mixtures based on substituted dialkoxyacetophenones, their use as photoinitiators, and photopolymerisable systems containing such mixtures - Google Patents

Abstract

Mixtures of at least one substituted dialkoxyacetophenone of the formula (I) <IMAGE> in which R<1> is an alkyl, alkoxyalkyl, chloroalkyl or alkyl-OCH2CH2OCH2CH2 group, R<2> is an alkyl, alkoxy, alkylthio, cycloalkyl or aralkyl group, chlorine, bromine, a further -CO-CH(OR<1>)2- group or a <IMAGE> group, X is a direct bond, O or S, R<3> is H, Cl, Br or an alkyl, alkoxy, alkoxycarbonyl or a further -CO-CH(OR<1>)2- group, and of at least one compound from the group consisting of optionally substituted anthraquinones, xanthones, thioxanthones, acridanones, benzoin derivatives, benzil ketal derivatives and/or optionally substituted benzophenones, exhibit a significantly controlled reactivity in their capacity to initiate the photopolymerisation of ethylenically unsaturated compounds or mixtures. The use of these mixtures as photoinitiators in the photopolymerisation of ethylenically unsaturated compounds or mixtures gives polymers which experience only extremely low levels of yellowing.

Description

Merck Patent Society July 3, 1981

with limited liability

Darmstadt

New mixtures based on substituted dialkoxyacetophenones, their use as photoinitiators and photopolymerizable systems containing such mixtures

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New mixtures based on substituted dialkoxyacetophenones, containing their use as photoinitiators and photopolymerizable systems such mixtures.

The invention relates to new mixtures which can be used as photoinitiators and are based on substituted Dialkoxyacetophenones and their use as Photoinitiators, especially for the photopolymerization of ethylenically unsaturated compounds and for the UV curing of printing inks, as well as photopolymerizable Systems containing such mixtures.

Photochemically initiated polymerization reactions have gained great importance in technology, in particular when it comes to quick hardening of thin layers, such as B. in hardening of lacquer and resin coatings on paper, metal and plastic or when drying printing inks, because these processes differ from conventional methods of printing and coating of objects are characterized by raw material and energy savings and a lower environmental impact. Since in these reactions none of the reactants is usually able to To absorb photochemically effective radiation to a sufficient extent, so-called photoinitiators have to be used be added, which are able to absorb radiated light or UV radiation and to form active starter radicals in the excited state. Depending on the type of reaction

3Q tion differs from the excited state one thereby two groups: A number of connections disintegrate after the energetic stimulation directly into active starter radicals, which in turn trigger the polymerization, while others

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Compounds in the excited state only react with another compound to form active starter radicals to form, which then trigger the polymerization. Both types of connections are made in the summarized below under the term initiators. Essential criteria for selection Such initiators include the type of reaction to be carried out and the ratio of the absorption spectrum of the initiator for the spectral energy distribution of the available radiation source, the solubility of the initiator in the reaction mixture, the dark storage stability of the with the The reaction system added to the initiator, as well as the influence on the end products by

-] 5 bene residues of the initiator and / or from it products formed during the photochemical reaction. In particular the speed of the The reaction depends strongly on the initiator used. That is why there has been no lack of attempts to find new ones To look for initiators and also new initiator mixtures, which in their capacity, the photopolymerization to initiate the curing of photopolymerizable systems of ethylenically unsaturated compounds, show increased reactivity.

As initiators for the photopolymerization of unsaturated Compounds so far are mainly benzophenone derivatives, benzoin ethers, benzil monoacetals, Dibenzosuberonderivate, Anthraquinones, Xanthones, Thioxanthones and α-Halogenacetophenonderi-

O ₀ vate has been established. However, the technical applicability of these substances is clearly restricted by a number of disadvantages. These include, among other things, the low dark storage stability of many photopolymerizable systems that work with these

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Initiators are mixed, low chemical stability and too low reactivity in the capacity that Photopolymerization of ethylenically unsaturated compounds or the curing of photopolymerizable compounds Initiate systems. Many of these known initiators cause yellowing with them produced polymers, which are particularly useful for coating light-colored substrate materials and for UV cured printing inks is highly undesirable.

For this last-mentioned field of application, the often low solubility of the known Initiators in the photopolymerizable system are a major disadvantage. Because printing inks usually Contain considerable amounts of colored pigments, which make up a large part of the radiated energy absorb without it becoming photochemically effective, a larger amount of initiator must be added here will. The known initiators often partially crystallize out; apart from this, that the crystallized parts can no longer have an initiating effect, damage the Crystallites formed after a while the printing plates made of relatively soft materials.

Furthermore, in the German Offenlegungsschriften 22 61 383 and 27 30 462 dialkoxyacetophenones described as photoinitiators, the disadvantages of the initiators known up to then in exhibit a lesser degree. These compounds, some of which are liquid, are usually photopolymerizable Systems more soluble than most of the usually solid initiators known up to that point and have good dark storage and chemical stability. In particular, however, in photopoly-

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merization with these initiators yellowing of the polymers only to a lesser extent than with the up to then common initiators observed. But despite the increased photoinitiating Effectiveness of these dialkoxyacetophenones in comparison 2U also show the other known initiators these compounds still have insufficient reactivity when initiating photopolymerization on. As a result, relatively long curing times are still required, which results in a non-optimal one Utilization of the UV irradiation systems leads.

The object was therefore to use ethylenic photoinitiators, especially for photopolymerization unsaturated compounds or for curing photopolymerizable systems, to find the physiological are harmless, sufficient dark storage stability in a mixture with the other reactants have no yellowing of the reaction products themselves or through their secondary products cause that in the usual photopolymerizable Systems have the highest possible solubility, which have a low surface tack of the cured coatings and at the same time the greatest possible reactivity in their capacity, initiate the curing of photopolymerizable systems, show and so even in low use concentrations are effective.

This problem was solved by providing new mixtures that can be used as photoinitiators, which has a considerably increased reactivity in its compared to the individual components Ability, the photopolymerization of ethylenically unsaturated compounds or the curing of photopolymerizable compounds Initiate systems, show.

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In addition, the mixtures according to the invention have good dark storage stability and the Advantage of the easy incorporation into the system to be polymerized, since these mixtures are usually are liquid. The with the help of the invention Initiator mixtures of cured polymers experience even less yellowing than those polymers which are obtained with a single component of these mixtures.

The invention thus relates to mixtures based on substituted which can be used as photoinitiators Dialkoxyacetophenones, which are characterized in that they

A) at least one compound of the general formula I.

CO-CH (OR ¹ ) ₂ / jx

wherein

R alkyl with 1-4 carbon atoms, alkoxyalkyl with 3-6 carbon atoms, chloroalkyl with 2-3 carbon atoms or alkYl-OCH ₂ CH ₂ OCH ₂ CH ₅ -, the alkyl group having 1-4 carbon atoms ,

R alkyl with 1-4 carbon atoms, alkoxy with 1-4 carbon atoms, alkylthio with 1-4 carbon atoms, cycloalkyl with 5-6 carbon atoms, aralkyl with 7-9 carbon atoms, chlorine, bromine, a far | re -CO-CH (OR) ₂ ~ group or a -X- ^ J ¹ V "group,

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X is a direct bond, oxygen or sulfur and

R is hydrogen, alkyl with 1-4 carbon atoms, alkoxy with 1-4 carbon atoms, chlorine, bromine, alkoxycarbonyl with 2-5 C atoms or a further -CO-CH (OR) "group,

included as well

B) at least one compound from the group consisting of

a) Anthraquinones of the general formula II

^? R ⁴

wherein

4th
R hydrogen, halogen, alkyl with 1-7 C-

Atoms or alkanoyl with 2-5 C atoms means

b) heteroxanthones of the general formula III

(III),

worm

Y is oxygen, sulfur or a -NR group and

R is hydrogen or alkyl with 1-7 carbon atoms

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and R has the meaning given for general formula II,

c) Benzoin derivatives of the general formula IV

wherein

R is hydrogen, alkyl with 1-7 carbon atoms or alkanoyl with 2-5 carbon atoms and

■ 7

R is hydrogen or alkyl with 1-7 carbon atoms,

d) benzil ketal derivatives of the general

Formula V

wherein

R denotes alkyl with 1-7 carbon atoms, and / or

e) Benzophenone derivatives of the general formula VI '

wherein

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9 10
R and R are identical or different and

Hydrogen, alkyl with 1-7 carbon atoms, alkanoyl with 2-5 carbon atoms or -N (R) ,, and

R is hydrogen, alkyl with 1-4 carbon atoms or substituted by -OH, -OAlk or -CN Alkyl with 2-4 carbon atoms, whereby Alk denotes alkyl with 1-4 carbon atoms,

mean.

The invention also relates to the use of these mixtures as photoinitiators, in particular for the photopolymerization of ethylenically unsaturated Compounds as well as for the UV curing of printing inks.

The invention also relates to a photopolymerizable one System containing at least one ethylenically unsaturated photopolymerizable compound and optionally other known and customary additives, which are characterized is that it is a mixture of at least one dialkoxyacetophenone of the general formula I and at least a compound from the group consisting of anthraquinones of the general formula II, heteroxanthones of the general formula III, benzoin derivatives of the general formula IV, benzil ketal derivatives of the general formula V and / or benzophenone derivatives of the general formula VI, preferably 0.1 to 20% by weight of such a mixture as a photoinitiator.

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The invention also relates to a process for the photopolymerization of ethylenically unsaturated Compounds, which is characterized in that one of the system to be polymerized before triggering the photopolymerization a mixture of at least one dialkoxyacetophenone of the general. Formula I and at least one compound from the group consisting of anthraquinones of the general Formula II, heteroxanthones of the general formula III, benzoin derivatives of the general Formula IV, benzil ketal derivatives of the general formula V and / or benzophenone derivatives of the general formula VI added as a photoinitiator. Preferably 0.1 to 20% by weight of such a Mixture added.

The substituted dialkoxyacetophenones of the general formula I, processes for their preparation and As already mentioned, their photoinitiating effectiveness is known from DE-OS 27 30 462 and shows 2ö compared to the previously known photoinitiators a number of advantages.

Anthraquinones, heteroxanthones, benzoin derivatives, benzil ketal derivatives and benzophenone derivatives and their photoinitiating activity have also been around known for a long time. These photoinitiators and photopolymerizable systems that contain these photoinitiators, are for example in the following review articles described: H.-G. Heine et al., Angew. Chem. 84, 1032 (1972); Angew.

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Chem., Internat. Edit. , 11: 974 (1972); S.P. Papas, UV Curing: Science and Technology (S.P. Pappas Edit., Technology Marketing Corp., 1978) 1-22.

The use of these compounds as sole photoinitiators in a photopolymerizable ■ However, the system is severely restricted by various disadvantages, in particular poor solubility of these compounds in the respective reaction systems and the strong tendency to yellow of the products cured with the help of these photoinitiators.

In general formula I, R preferably denotes alkyl having 1-4 carbon atoms, unbranched alkyl is preferred, especially ethyl. But R can also be alkoxyalkyl with 3-6 carbon atoms, chloroalkyl with 2-3

C atoms or AIkYl-OCH ₂ CH ₂ OCH ₂ CH ₂ -, the alkyl group having 1-4 C atoms.

R preferably denotes alkyl having 1-4 carbon atoms, in particular Methyl; Alkoxy with 1-4 carbon atoms, especially methoxy; Chlorine; another -CO-CH (OR Κ group, where R is in particular the above as

has preferred meanings mentioned, or an f " Vρ

-Group, where X is a direct bond, oxygen or sulfur and R is preferably hydrogen or a further -CO-CH (OR), - group. But R can also be alkylthio with 1-4 carbon atoms, cycloalkyl with 5-6 carbon atoms, aralkyl with 7-9 carbon atoms or

Mean bromine. Furthermore, R can have the following meanings have: alkyl with 1-4 carbon atoms, especially

3Q special methyl, alkoxy with 1-4 carbon atoms, chlorine, Bromine or alkoxycarbonyl with 2-5 carbon atoms.

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The preparation of compounds of the general formula I is known and is, for example, in DE-OS 27 30 462 described.

In the case of the anthraquinones of the general formula II, R preferably denotes hydrogen, chlorine or unbranched or branched alkyl with 1-8 carbon atoms, preferably with 2-6 carbon atoms, in particular with 3-5 carbon atoms, also fluorine, bromine or alkanoyl with 2-5 carbon atoms.

In the case of the heteroxanthones of the general formula III, Y is preferably oxygen or sulfur, but also -NR -, where R is in particular hydrogen or methyl, but also unbranched or branched

4 branched alkyl with 2-7 carbon atoms. R has the above given, in particular the meanings mentioned as preferred.

In the benzoin derivatives of the general formula IV, R preferably denotes hydrogen or unbranched or branched alkyl with 1-4 carbon atoms, but also alkyl with 5-7 carbon atoms or alkanoyl with 2-5

Carbon atoms. R denotes hydrogen or unbranched or branched alkyl with 1-7 carbon atoms, in particular with 1-4 carbon atoms.

For the benzil ketal derivatives of the general formula V is R unbranched or branched alkyl with 1-7 carbon atoms, preferably with 1-4 carbon atoms, in particular Methyl.

For the benzophenone derivatives of the general formula

9 10 VI, the substituents R and R are preferably the same, but they can also be different. she

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are preferably hydrogen, alkyl with 1-4 C atoms, which can be unbranched or branched, or -N (R) ₂ . Further meanings for R and R are unbranched or branched alkyl with 5-7 carbon atoms, alkanoyl with 2-5 carbon atoms, in particular acetyl; Carboxyl, or alkoxycarbonyl with 2-5 carbon atoms. R preferably denotes hydrogen, methyl or ethyl, but also propyl, isopropyl, butyl, sec-butyl, tert-butyl or alkyl with 2-4 carbon atoms substituted by -OH, -OAIk or -CN, where Alk is one Alkyl radical with 1-4 carbon atoms.

The preparation of compounds of the general formulas II, III, IV, V and VI is described, for example, in Houben-Weyl, Vol. VII / 3 c; M. Davis et al., J. Oil Col. Chem. Assoc. 6I ₁ , 256 (1978); H.-G. Heine, Liebigs Ann. 735: 56 (1970); DE-OS 24 22 183 and Houben-Weyl, Vol. VI1 / 2 a.

The compounds from group B (anthraquinones of the general formula II, heteroxanthones of the general formula III, benzoin derivatives of general formula IV, benzil ketal derivatives of general formula V and / or benzophenone derivatives of general formula VI) can be added to the compounds of the general formula I (group A) in proportions of 0.1 to 99.9% by weight, preferably 0.1 % By weight up to the saturation concentrate, added will. Mixtures in which the individual components A and B are combined in one additive are particularly advantageous composition of 99: 1 to 80:20 are available. The mixtures obtained in this way are liquid and possess this has the advantage of being easy to incorporate into the system to be polymerized.

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The mixtures according to the invention of at least one compound of the general formula I (component A) and at least one compound from group B can be used as photoinitiators according to the present invention for the photopolymerization of ethylenically unsaturated compounds and for curing photopolymerizable systems which contain such compounds, and in particular also for UV curing used by printing inks. This ver

10 · turn around takes place in the usual way. The invention Mixtures are added to the systems to be polymerized generally in amounts of 0.1 to 20% by weight, preferably 0.5 to 12% by weight, added. This addition is usually done by simply loosening it and stirring in, since most of the systems to be polymerized and the mixtures according to the invention are liquid or at least readily soluble. Under a system to be polymerized there is a mixture of mono- or polyfunctional ethylenically unsaturated monomers that can be initiated by free radicals, Oligomers, prepolymers, polymers or mixtures of these oligomers, prepolymers and polymers Understood with unsaturated monomers, which is usually other additives such. B. Antioxidants, May contain light stabilizers, dyes, pigments, reaction accelerators. As unsaturated Compounds are all those whose C = C double bonds through, for example, halogen atoms, Carbonyl, cyano, carboxy, ester, amide, ether or aryl groups or by conjugated others Double or triple bonds are activated. Examples of such compounds are vinyl chloride, Acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, methyl, ethyl, η or tert. Butyl,

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Cyclohexyl, 2-ethylhexyl, benzyl, phenyloxyethyl, Hydroxyethyl, hydroxypropyl, lower alkoxyethyl, tetrahydrofurfuryl acrylate or methacrylate, vinyl acetate, -propionate, -acrylate, -succinate, N-vinylpyrrolidone, N-vinylcarbazole, styrene, divinylbenzene, substituted styrenes, as well as the mixture of such unsaturated compounds. Also polyunsaturated Compounds such as, for example, ethylene diacrylate, 1,6-hexanediol diacrylate, propoxylated bisphenol A diacrylate and dimethacrylate, trimethylol propane diacrylate and pentaerythritol triacrylate can with the Photoinitiators according to the invention are polymerized. Comes as photopolymerizable compounds furthermore unsaturated oligomers, prepolymers or polymers and their mixture with unsaturated monomers in question. These include, for example, unsaturated polyesters, unsaturated acrylic materials, Epoxy materials, urethanes, silicones, amine polyamide resins and in particular acrylated resins such as acrylate

"2nd silicone oil, acrylated polyester, acrylated Urethanes, acrylated polyamides, acrylated soybean oil, acrylated acrylic resin, expediently mixed with one or more acrylates of a mono-, Di- or polyalcohol.

The photopolymerizable compounds or systems can by the addition of known thermal inhibitors or antioxidants, such as Hydroquinone or hydroquinone derivatives, pyrogallol, thiophenols, nitro compounds, ß-naphthylamines

3Q or ß-naphthols stabilized in the usual amounts without significantly impairing the initiator action of the mixtures according to the invention will. Such additives are primarily intended to prevent premature polymerization during production of the systems can be prevented by mixing the components.

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Furthermore, small amounts of light stabilizers, such as benzophenone derivatives, Benztriazole derivatives or phenyl salicylates, can be added.

Photopolymerizable systems are used to exclude the inhibiting effect of atmospheric oxygen often paraffin or similar waxy substances are added. Due to a lack of solubility in the polymer these float out at the beginning of the polymerization and form a transparent surface layer, which prevents the entry of air. The atmospheric oxygen can, for example, also by introducing autoxidizable groups, such as. B. allyl groups, in the system to be hardened are deactivated.

Furthermore, the photopolymerizable systems known pigments or dyes, such as are z. Am photochemically curing printing inks are common, can be added. In this case the Photoinitiator amount selected higher, for example 6 to 12% by weight, while for colorless photopolymerizable products 0.1 to 3% by weight in most cases fully sufficient. Depending on the intended use, other fillers such as talc, gypsum or silica, Fibers, organic additives such as thixotropic agents, leveling agents, other binders, lubricants, Matting agents, plasticizers, wetting agents, silicones to improve the surface quality, Anti-floating agents or small amounts of Solvents are added.

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In certain cases it can be particularly advantageous to add reaction accelerators to the mixtures which can be used as photoinitiators and to the photopolymerizable systems. Such reaction accelerators are, for example, organic amines, phosphines, alcohols and / or thiols, all of which have at least one CH group in the α position to the heteroatom. Particularly suitable are, for. B. primary, secondary and tertiary aliphatic, aromatic, araliphatic or heterocyclic amines, as z. As described in U.S. Patent 3,759,807. Examples of such amines are butylamine, dibutylamine, tributylamine, cyclohexylamine, benzyldimethylamine, dicyclohexylamine, triethanolamine, N-methyldiethanolamine, phenyldiethanolamine, piperidine, piperazine, morpholine, pyridine, quinoline, ethyl p-dimethylaminobenzoate, ethyl dimethylaminoate, 4,4-dimethylaminobenzoate, butaminobenzoate, 4,4-dimethylaminobenzoate ^ bis-dimethylamino-benzophenone (Michler's ketone), or ^4.4> -Bisdiethylaminobenzophenon. Tertiary amines such as, for example, trimethylamine, triethylamine, tri-isopropylamine, tributylamine, octyl-dimethylamine, dodecyl-dimethylamine, triethanolamine, N-methyl-diethanolamine, N-butyldiethanolamine, tris (hydroxypropyl) amine, dimethylaminobenzoic acid ketonyl ester, Michler's alkyl ester are particularly preferred.

Furthermore, as reaction accelerators, for example trialkylphosphines, sec. Alcohols and thiols in question.

In many cases they act as photoinitiators Usable mixtures and photopolymerizable systems that additionally act as reaction accelerators still contain at least one organic amine, a particularly preferred form of the present invention represent.

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If necessary, these reaction accelerators are generally added to the mixture according to the invention or added to the photopolymerizable system in such amounts that reaction accelerators and Individual component B of the mixture according to the invention are present in a weight ratio of 1: 0.01 to 1:10. A weight ratio of reaction accelerator to individual component B of 1: 0.05 to 1: 1.

0 The phrase "photopolymerization of ethylenic Unsaturated compounds "is to be understood in the broadest sense. This includes, for example, further polymerisation or the cross-linking of polymeric materials, e.g. B. of prepolymers, homo-, co- and terpolymerization of simple monomers and also the combination of the types of reaction mentioned.

The photopolymerization takes place according to known methods by irradiation with light or UV radiation of the wavelength range from 250 to 500 nm, preferably from 300 to 400 nm. As radiation sources Sunlight or artificial spotlights can be used. Advantageous are z. B. High pressure mercury, -Medium pressure or low pressure lamps, xenon and tungsten lamps; Laser light sources can also can be used.

The mixtures according to the invention can be used as photoinitiators in the UV curing of thin layers, such as z. B. paper, plastic and metal coatings are used and offer special advantages than Initiators for the photocuring of printing inks and for photocurable systems for the production of printing plates.

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In particular, the photo-curing of printing inks has become very important because of the drying time of the binder is a decisive factor in the speed of production of graphic products and is on the order of fractions of a second. In the manufacture of printing plates are z. B. Mixtures of soluble linear polyamides with photopolymerizable monomers, for example acrylamides, and a photoinitiator are used. Films or plates from these systems are exposed over the negative or over the positive of the artwork and the unhardened parts are then eluted with a solvent.

In the following examples, the preparation and use of the mixtures according to the invention are as Photoinitiators in the photopolymerization of ethylenically unsaturated compounds described in more detail. Unless otherwise stated, the concentration and percentage data are based on weight based.

example 1

A resin mixture of 100 parts of titanium dioxide (anatase),

(R) 63.5 parts of a urethane acrylate resin (Uvimer ^ ' 530 from Bayer, Leverkusen), 36.5 parts of 1,4-butanediol and 4 parts of N-methyldiethanolamine are added after adding 2.5% of the initiator mixture from 90 parts of 4- (diethoxyacetyl) -toluene and 10 parts of 2-chloroanthraquinone under yellow light (to eliminate uncontrollable daylight influences), in a thickness of 15 μm, applied to aluminum foil. These films are then cured using a minicure device (from Primäre ITP (England)) in which the paint samples are placed on a conveyor belt

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at variable speed under a high pressure mercury lamp (Radiation intensity 80 W / cm) moved past and be irradiated in the process. The film obtained after the irradiation is tack-free and scratch-resistant.

c example 2

A resin mixture of 100 parts of titanium dioxide (anatase),

(R) 63.5 parts of an epoxy acrylate resin (Laromer ^v ' 2555 from BASF, Ludwigshafen), 36.5 parts of 1,4-butanediol and 4 parts of N-methyldiethanolamine are mixed with 2.5% by weight of the initiator mixture from 85 Parts of 4- (dimethoxyacetyl) isopropylbenzene and 15 parts of 2.-1sopropylthioxanthone were added and, as described in Example 1, applied to aluminum foil and irradiated. A white, tack-free, fully cured surface coating is obtained.

Example 3

A resin mixture of 100 parts of titanium dioxide (anatase), 63.5 parts of SVP ^ ' 1928 (resin from Degussa, Frankfurt / M), 36.5 parts of 1,4-butanediol and 4 parts of N-methyldiethanolamine is mixed with 2, 5% by weight of the initiator mixture of 85 parts of 1,4-bis (diethoxyacetyl) benzene and 15 parts of 2-methylxanthone are added and, as described in Example 1, applied to aluminum foil. After irradiation, a glossy, colorless, tack-free coating is obtained.

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Example 4

A resin mixture of 45 parts of an acrylate resin

6628-0 from Röhm, Darmstadt), 18.5 parts

len of another acrylate resin (Plex '^ 6673-0 from Röhm, Darmstadt) and 36.5 parts of butanediol 1,4-diacrylate is with 2.5 wt.% Of the initiator mixture of 90 parts of 4,4'-bis (dimethoxyacetyl) -diphenyl oxide and 10 parts of acridanone and, as described in Example 1, on aluminum foil upset. After irradiation, a hard, colorless coating is obtained.

Example 5 *

A resin mixture of 100 parts of titanium dioxide (anatase),

(B.) 63.5 parts of an epoxy acrylate resin (Laromer ^v '2555 from BASF, Ludwigshafen) and 36.5 parts of butanediol 1,4-diacrylate is mixed with 2.5% by weight of a mixture of 99.9 parts of 4- (Dipropyloxyacetyl) ethylbenzene and 0.1 part of benzoin were added and applied to aluminum foil. After irradiation, a white, tack-free, fully hardened surface coating is obtained.

Example 6

A resin mixture of 100 parts of titanium dioxide (anatase),

CR) 63.5 parts of an acrylate resin (Plex ^v '6628-0 from Röhm, Darmstadt), 18.5 parts of another acrylate resin (Plex ^ ' 6673-0 from Röhm, Darmstadt) and 36.5 parts of butanediol 1,4-diacrylate is mixed with 2.5% by weight of a mixture of 80 parts of 4- (dimethoxyacetyl) chlorobenzene and 20 parts of benzil dimethyl ketal and applied to aluminum foil.

The film obtained after the irradiation is tack-free and scratch-resistant.

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Example 7

(R) 63.5 parts of an epoxy acrylate resin (Laromer ^ ' 8555 from BASF, Ludwigshafen) are rubbed with 36.5 parts of butanediol diacrylate and 20 parts of Heliogen blue on a three roller. 3% by weight of a mixture of 90 parts of 4- (diethoxyacetyl) are added to the blue printing ink obtained. buty! benzene and 10 parts of benzophenone were added. After printing on art paper in 1 µm thickness, UV light is irradiated. The printed sheets obtained can be stacked immediately.

Example 8

A printing ink is produced analogously to Example 7. The photoinitiator used is 2% by weight of a mixture from 60 parts of 4- (dimethoxyacetyl) -toluene, 20 parts of benzophenone and 20 parts of 4,4'-bis (dimethylamine) -benzophenone added. After printing on art paper in 1 µm thickness, UV light is irradiated. The printed sheets obtained can be stacked immediately.

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Claims (9)

Merck Patent Society
with limited liability Darmstadt Patent claims .: 1, Mixtures based on substituted dialkoxyacetophenones that can be used as photoinitiators, characterized in that they A) at least one compound of the general formula I. ) ι wherein R alkyl with 1-4 carbon atoms, alkoxyalkyl with 3-6 carbon atoms, chloroalkyl with 2-3 carbon atoms Atoms or alkyl-OCH ₂ CH ₂ OCH ₂ CH ₂ -, where the alkyl group has 1-4 C atoms, R alkyl with 1-4 carbon atoms, alkoxy with 1-4 Carbon atoms, alkylthio with 1-4 carbon atoms, cycloalkyl with 5-6 carbon atoms, aralkyl with 7-9 carbon atoms, chlorine, bromine, another, -CO-CH (0R ^x ) ₂ group or a -X-r_> group, GSPHA25 G X is a direct bond, oxygen or sulfur and R hydrogen, alkyl with 1-4 carbon atoms, Alkoxy with 1-4 carbon atoms, chlorine, bromine, alkoxycarbonyl with 2-5 carbon atoms or a further -CO-CH (OR "^ group mean, included as well B) at least one compound from the group consisting of a) Anthraquinones of the general formula II (II), wherein 4th
R denotes hydrogen, halogen, alkyl with 1-7 carbon atoms or alkanoyl with 2-5 carbon atoms, b) heteroxanthones of the general formula III wherein Y oxygen, sulfur or an -NR Group and GSPHA25 G R is hydrogen or alkyl with 1-7 carbon atoms and R is the one given for the general formula II Has meaning c) Benzoin derivatives of the general Formula IV CO-c (OR ⁶ ) R ⁷ - / "^ (IV), wherein R ^{6 is} hydrogen, alkyl with 1-7 carbon atoms or alkanoyl with 2-5 carbon atoms and R is hydrogen or alkyl with 1-7 carbon atoms mean, d) benzil ketal derivatives of the general formula V. <^ - C (OR ⁸ ) ₂ -CO - // wherein R ⁸ denotes alkyl with 1-7 carbon atoms, and or e) Benzophenone derivatives of the general formula VI wherein GSPHA25 G 9 10
R and R are identical or different and Hydrogen, alkyl with 1-7 carbon atoms, alkanoyl with 2-5 carbon atoms, carboxyl, alkoxycarbonyl with 2-5 carbon atoms or -N (R ¹¹ ) _£ and R is hydrogen, alkyl with 1-4 carbon atoms or substituted by -OH, -OAIk or -CN Alkyl with 2-4 carbon atoms, whereby Alk denotes alkyl with 1-4 carbon atoms, mean. 2. Mixtures according to claim 1 which can be used as photoinitiators, characterized in that they contain the components A and B in a weight ratio of 99.9: 0.1 up to the saturation concentration of B. contained in A. 3. Use of mixtures according to claim 1 or 2 as photoinitiators. 4. Use of mixtures according to claim 1 or 2 as photoinitiators for photopolymerization ethylenically unsaturated compounds. 5. Use of mixtures according to claim 1 or 2 as photoinitiators for the UV curing of printing inks. 6. Photopolymerxerbaren system containing at least one ethylenically unsaturated photopolymerizable Compound and optionally other known and customary additives, characterized in that that it contains a mixture according to claim 1 or 2 as photoinitiator. GSPHA25 G _ ^ -—_ 3! 2 ο 4 3 7. Photopolymerizable system according to claim 6, characterized characterized in that it contains 0.1 to 20% by weight of a mixture according to claim 1 or 2 as photoinitiator contains. 8. Process for the photopolymerization of ethylenic unsaturated compounds, characterized in that the system to be polymerized is in front of a mixture according to claim 1 or 2 is added as a photoinitiator to initiate the photopolymerization. 9. The method according to claim 8, characterized in that the system to be polymerized before Triggering of the photopolymerization 0.1 to 20% by weight of a mixture according to claim 1 or 2 as photoinitiator clogs. GSPHA25 G