DE2616408A1 - MIXTURES POLYMERIZABLE BY UV RADIATION - Google Patents

Description

Mixtures polymerizable by UV radiation

Addition to patent ... _o ,., (patent application P 22 32 365.5)

Subject of the main patent ". .. ₀ .. (patent application P 22 32 365 »5) are mixtures of compounds with at least one polymerizable CC multiple bond that can be polymerized by UV irradiation or of mixtures containing compounds with a photoinitiator, optionally with conventional additives, which are used as photoinitiators by monoketals aromatic 1,2-diketones of the formula

RACC- A -R ' ti / \

0 0 0 X X '

where A and A ^{1 are} six-membered aromatic radicals of the same or different types substituted by radicals R and R ¹ and X and X 'optionally represent monovalent radicals bearing substituents or X and X ¹ together represent a Cp- to Cn-alkylene radical.

In a further embodiment of the invention mentioned, new non-cyclic asymmetrical monoketals of aromatic 1.2-diketones found that are easy to prepare and in polymerizable Mixtures or masses are sufficiently stable in their usual processing and storage, on the other hand one have good reactivity in the radiation curing of the masses and produce a particularly low yellowing of the same.

The present invention thus relates to UV irradiation polymerizable mixtures of a) compounds having at least one polymerizable C-C multiple bond or of Mixtures containing such compounds with b) monoketals

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of aromatic 1,2-diketones as photoinitiators according to

Patent (patent application P 22 32 ^ 65.5), which thereby

are characterized as being monoketals of aromatic 1,2-diketones non-cyclic unsymmetrical monoketals der formula (I) below

A ¹ - C - C - A ² (I)

dd / \

ο O ₁ ο

R ^X l \ ^d

1 2
wherein A and A are identical or different, optionally substituents

carrying aromatic residues and

1 2
R and R, if appropriate, hydrocarbon radicals bearing substituents

with 1 to 12 carbon atoms of different types.

Acyclic unsymmetrical monoketals of aromatic 1.2-diketones of this type are not yet known. The new photoinitiators contained in the mixtures according to the invention can be easily and advantageously produced if the aromatic 1,2-diketones on which they are based (formula II)

A ^1- CCA ² (II)

I! M.

0 0

in an organic solvent with an alkylating agent (R ¹ ) X and an alcoholate (R ² O) Me, where R ¹ and R ^{2 have} the meaning given above and represent different radicals, η and m integers from 1 to 3, X a mono- to tribasic acid residue and Me a metal of the first 3 main groups of the periodic table of the elements.

Suitable aromatic diketones of the formula II are particularly

1 2
those in which A and A represent a substituted benzene radical, the substituents mainly being C.- to ^ "- hydrocarbon radicals such as alkyl or phenyl radicals, C ₁ - to C ₁₀ -alkoxyalkyl radicals, C ^ - to C _Q -alkoxy radicals, C ₁ - to Cg-alkylthio radicals or halogen atoms are possible.

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Examples of aromatic 1,2-diketones, from which the monoketals according to the invention are derived, are benzil and substituted benzils such as 4,4'-dimethylbenzil, 4,4'-diisopropylbenzil, 4,4'-diphenylbenzil, 2,2 ^f -dimethoxybenzil , 4,4'-Diine thoxib en zil, 4-methylbenzil, 3-methoxibenzil, 2,2'-dimethylbenzil, 4-chloro-4'-phenylbenzil, 4,4'-dichlorobenzil, 3,3'-dibromobenzil, 2 , 4,2 ', 4'-tetramethylbenzil, 2,4,6-trimethylbenzil, 2,4-dichloro-4'-methylbenzil. The preparation of these benzil derivatives is described in the literature; it can take place, for example, by oxidation of the corresponding benzoins.

Suitable for the production of the asymmetrical monoketals Alkylating agents have the formula (R) X mentioned and are esters of mono- to tribasic acids, in particular of a Acids containing sulfur, a phosphorus or a halogen atom. The esters of sulfuric acid, the sulphurous ones, should be mentioned Acid, phosphoric acid and phosphorous acid, the esters of hydrohalic acids such as the chlorides and bromides and iodides as well as the aliphatic and aromatic sulfonic acids such as the mesylates, tosylates, brosylates and benzenesulfonates. The sulfates, halides and sulfonic acid esters are particularly suitable, of which the sulfates and bromides are preferred are used, examples of alkylating agents are dimethyl sulfate, Diallyl sulfate, dicrotyl sulfate, benzyl bromide or Allyl bromide.

The radical R represents, if appropriate, substituents-bearing hydrocarbon radicals with 1 to 12 carbon atoms, of which the corresponding alkyl (especially C. Aralkyl-), alkenyl (especially C 1 -C "-alkenyl-), aralkenyl (especially Cg- or C ..- aralkenyl-) radicals and the groups Z- (CHR ³ -CHR ^) - or Z- (CHR ³ ) -, where ρ is a number from 1 to 3, R ³ and R ^ H or CH, and Z is a halogen atom or OR ^, SR ⁵ , OAr

Z) he

or SAr can represent with R = C.- to C ^ -alkyl or C ₁ - to C -alkoxialkyl and Ar = six-membered aromatic radical.

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As alcoholates are used for the production of the asymmetrical Monoketal alcoholates not corresponding to the alkylating agent

with residues R used, e.g. when using dimethyl sulfate an ethylate such as sodium ethylate or potassium methylate or when using allyl bromide, e.g. sodium methylate.

ο Otherwise, the information given above on the R radicals apply mutatis mutandis to the type of R radicals. Are preferred the alcoholates of sodium and potassium.

Organic solvents for the production of the monoketals include aromatic solvents such as benzene or Toluene and especially dimethylformamide and dioxane.

Theoretically, for the preparation of the monoketals, 1 / n moles of alkylating agents of the formula (R) X explained above with 1 mole 1,2-diketone and 1 / m mol alcoholate of the formula (R 0) Me also explained above, where η and m are the numbers η and m, respectively in the formula of the alkylating agent or alcoholate used to generate the unsymmetrical monoacetals of the aromatic 1,2-diketones. In general, however, it will preferred some reactants in excess amounts to use to achieve full implementation. So you can per mole of 1,2-diketone l / n to 10 / n mol or more, preferably 1 / n to 4 / n mol, alkylating agent and 1 / m to 10 / m mol or more, preferably 1 / m to Vm mol, alcoholate use. A particularly preferred way of working up the reaction solution is to post the solvent Addition of water by azeotropic distillation from the reaction mixture to remove. After that, the monoacetal, which is insoluble in water, separates out as crystalline, especially on cooling Substance or as an oil in often analytically pure or almost analytically pure form.

In the mixtures or compositions according to the invention, there are advantageously the mentioned monoacetals of the 1,2-diketones in amounts of 0.01 to 10 and preferably from 0.05 to about 4 wt. ^, based on the photosensitive mixture or the photopolymerizable Compounds included.

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All compounds are for the mixtures or compositions according to the invention with at least one C-C multiple bond which, when mixed with the photoinitiator, leads to a polymerization can be stimulated. Compounds and substances with C-C double bonds, which are caused by e.g. aryl, carbonyl, Amide, ester, carboxy or cyanide groups, halogen atoms or C-C double or C-C triple bonds are activated. Examples include styrene, vinyl toluene and acrylic acid and methacrylic acid and its esters, cyanides or amides, e.g. acrylamide, N-methylolacrylamide, dieters of 1 mol glycol and 2 Moles of N-methylolacrylamide, methyl methacrylate, methylenebisacrylamide, m-phenylene-bis-acrylamide or m-xylylene-bisacrylamide and also diurethanes with at least two (meth) acrylic groups.

The person skilled in the art is familiar with the photopolymerizable compounds and their selection for the particular intended use of the mixtures is, unsaturated and / or saturated polymers and / or the known additives, such as inhibitors, can be used in a known manner against thermal polymerization, such as hydroquinone or tert-buty! hydroquinone, skin-forming substances such as paraffin, Leveling aids such as silicone oil, fillers and / or pigments or dyes can be added in the usual amounts. Such mixtures are known to the person skilled in the art and the type and amount of Additives depend in particular on the type of use of the mixtures away.

The new photoinitiators in polyester resins have proven particularly useful in the production of coatings curable with UV radiation. Suitable compositions of unsaturated polyester resins are available, for example, from a mixture of (1) HO to 80 percent by weight of a conventional unsaturated polyester; (2) up to 15 percent by weight of at least one copolymerizable, olefinically unsaturated monomer; (3) 0 »5 to 5 percent by weight of a photoinitiator and optionally (4) other customary additives.

Suitable unsaturated polyesters (1) here are the usual ones Polycondensation products from polyvalent, especially two-

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Valuable carboxylic acids with polyvalent, especially divalent Alcohols are linked ester-like, and optionally additional residues of monobasic carboxylic acids and / or residues of monovalent Contain alcohols and / or residues of hydroxycarboxylic acids.

Suitable olefinically unsaturated monomeric compounds (2) for the unsaturated polyester resins are all those customary with unsaturated ones Polyesters copolymerizable monomeric compounds, in particular vinyl aromatics, such as styrene and the esters of acrylic acid or methacrylic acid with alkanols with 1 to 8 Carbon atoms, such as acrylic acid tert-butyl ester or methacrylic acid methyl ester, and mixtures of these monomers. In the mixtures that are preferably used, component (2) is 60 to 15, preferably 50 to 25 percent by weight.

The new photoinitiators are also advantageous in photopolymerizable form Masses used in the production of systems of optical information fixing, in particular for the production used by photopolymer printing plates or by photoresist layers .

Suitable mixtures with compounds with at least one polymerizable For this purpose, C-C multiple bonds are mixtures of about 10 to 60 and preferably 15 to 35 percent by weight of monomers with predominantly at least two photopolymerizable C-C double bonds, e.g. di (meth) acrylates of aliphatic Diols, bis (meth) aerylamides of aliphatic or aromatic diamines with 2 to 8 carbon atoms, or monomers in addition to at least two (meth) acrylic groups ester or amide as well as urethane or contain urea groups, with 90 to 40 and preferably 85 to 65 percent by weight in an organic solvent such as an alcohol, ketone or an ether, soluble polymer. as Polymers come, for example, copolyamides, such as those from E-caprolactam, Hexamethylene diammonium adipate and ρ, ρ'-diaminodicyclohexylmethane adipate, also including soluble polyurethanes, polyureas, butadiene or isoprene copolymers Block copolymers or soluble cellulose derivatives, in question.

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More information about the selection of suitable monomers and / or polymers and / or of mixtures and above them. Processing is sufficient for those skilled in the art in the known patent literature described.

The light that triggers the photopolymerization or photocrosslinking of the mixtures is used as radiation sources with particular advantage those that emit light with a wavelength between 230 and 450 nm. Come first and foremost Radiation sources with emission maxima in the range from 300 to 38Ο nm or those that have a sufficiently high proportion of Emit light of this wavelength range in question. Mercury pressure lamps are particularly suitable, however also high and low pressure mercury tracers and superactinic fluorescent tubes. The lamps mentioned can optionally be endowed.

Mixtures according to the invention containing the new photoinitiators are suitable for the production of coatings, especially those based on polyester resins, e.g. for production of photopolymer printing plates, for the production of holograms, photoresist lacquers, poromer files, for fixing information in general and for UV-curable printing inks. Compared to mixtures containing symmetrical benzil monoacetals of the benzil dimethyl acetal type, they are distinguished by the fact that they show less yellowing of the hardened masses cause.

The parts and percentages given in the following examples are based on weight. Volume parts relate to Divide as liters to kilograms.

example 1

To a solution of 52.5 parts of benzil and 68.4 parts of benzyl bromide sulfate 21.6 parts are added to 400 parts by volume of dimethylformamide at room temperature with stirring over the course of 3 hours Add sodium methylate in portions. The reaction mixture is then stirred for a further 30 minutes at room temperature and then poured into

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2,000 volume cencils v / ater stirred in. The falling precipitation is filtered off, washed with water and dried. Then it is slurried in 150 parts by volume of petroleum ether, suctioned off, washed once with petroleum ether and dried. 62.0 parts of benzilmethylbenzyl monoacetal are obtained with a Melting point from 83 to 84 ° C.

Example 2

To a solution of 52.5 parts of benzil and 63 parts of dimethyl sulfate 34 parts of sodium ethylate are added to 250 parts by volume of dioxane at room temperature with stirring over the course of one hour added in portions. After adding 300 parts by volume of water and 22 parts of solid sodium hydroxide solution, the reaction mixture becomes 30 Heated under reflux for minutes, then 350 parts by volume of dioxane-water azeotrope are distilled off from the reaction mixture and the remaining residue, after cooling to room temperature, extracted with 150 parts by volume of chloroform. The chloroform extract 2 parts of animal charcoal are added, the mixture is boiled, filtered and the solvent is evaporated off on a rotary evaporator. The oily, largely colorless residue becomes crystalline after a while. Melting point: 52 to 54 ° C.

Example 3

To a solution of 105 parts of benzil and 121 parts of allyl bromide 48 parts are added to 500 parts by volume of dimethylformamide at room temperature with stirring over the course of 2.5 hours Add sodium methylate in portions. After adding 2,000 Parts by volume of water, the reaction mixture is extracted four times with 100 parts by volume of chloroform and the combined Chloroform extracts are then washed three times with 200 parts by volume of water each time. The chloroform phase is on The rotary evaporator is concentrated and the residue is then distilled in vacuo. 115 parts of benzil methyl allylacetal are obtained, that boils at 135 to 136 ° C / 0.3 mm Hg.

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In a manner analogous to that given in Example 3, benzilmethylcrotyl monoacetal is prepared with a boiling point of 140 to 145 ° C./0.3 mm Hg. Yield: 119 parts (80 % of theory).

Example 5

An unsaturated polyester is prepared by esterifying 431 parts of maleic anhydride and 325 parts of phthalic anhydride with 525 parts of 1.2-propylene glycol. After adding 0.01 % hydroquinone, a 66% solution in styrene is prepared from the polyester (solution A).

97 parts of solution A are mixed with 3 parts of photoinitiator (solution B). The storage stability (onset of gelation) of this mixture is determined ^{at 60 ° C. with the exclusion of light.} For the Photohärtungsversuche the solution B 10 parts of a 1 $ solution of paraffin was (softening range 50 to 52 ⁰ C) was added in styrene to 100 parts and applied the resin-coated photographic paper hardboard with a film applicator (gap width 500.um). After about

/ 1

After airing for 2 minutes, the films are exposed to fluorescent lamps with a high proportion of UV light, which are arranged at a distance of 4 cm are exposed. The hardening rate is determined by measuring the pendulum hardness according to König (DIN 53157) and is in Table 1 compiled together with the color measurements of the cured films,

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Table 1

Color measurement of the films:

Photoinitiator Pendulum hardness
after minutes
'4 8 10 104 108 Yellowness
Index after
the exposure Bearing rod
at 60 ⁰ C
(Hours.) Benzilmethylbenzyl
monoacetal 90 92 99 18.5 78 Benzilmethylallyl
monoacetal 62 98 104 13.8 56-71 Benzil methyl crotyl
monoacetal 74 105 108 11.6 not
measured Benzil dimethyl mono-
acetal 92 21.1 80-105 Example 6

A reaction product of 1 mol of bisphenol A diglycidyl ether with 2 mol of acrylic acid is dissolved in 65% in butanediol diacrylate. This 3 percent by weight of the photoinitiators listed in Tables 2 and 3 are added to the solution. The clear coats are in a Layer of 80 µm, knife-coated onto white photographic paper and with a high-pressure mercury lamp, output 80 watts / cm arc length irradiated. The distance between the lamp and the paint film is 10 cm. The samples are on a continuous basis in its running speed controllable conveyor belt passed under the UV lamp. The conveyor belt speed (m / min) is determined, at which a scratch-resistant hardening of the paint film can be achieved.

"Scratch-resistant curing" means that vigorous rubbing of the paint surface with the fingernail does not result in any interruption the film surface leads. In addition, the degree of whiteness (according to Berger) is determined on the samples cured at 11 m / min.

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Table 2

Photoinitiator max.Curing whiteness ^x '

speed (m / min) (according to Berger)

Benzoin n-butyl ether 16 93 _f 3

p-tert-butyl-trichloro-16 94.0

acetophenone

Benzil dimethyl ketal 24 92.7

Benzil methylbenzyl ketal 24 94.0

^x ^ the higher value indicates less yellowing.

After 5 days storage at 20 ° C and 65 ⁰ C are tested with the offset photoinitiators clearcoats again (s. Table 3)

Table 3

Photoinitiator max. Curing speed in

m / min after 5 days of storage at

Benzoin n-butyl ether

p-tert. Butyl-1 rieh loracetophenone Benzil dimethylket al Benzil methyl benzyl ketal

A urethane acrylate, prepared by reacting 1 mole of a diisocyanate with 2 moles of hydroxypropyl acrylate, was dissolved 70 % - ± s in 1,1,1-trimethylolpropane triacrylate, and 2% by weight of benzilmethyl-ethyl ketal and 3% by weight of methyldiethanolamine were added as the chain-transferring amine. The solution is knife-coated onto a glass plate in a layer of 20 μm and exposed as described in Example 5. The clear lacquer hardens scratch-resistant at a belt speed of 50 m / min

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20 ⁰ C 65 ⁰ C 14th vorz. polymerized 16 no hardening 24 24 24 24

Claims (1)

P at e nt to s ρ ru ch Mixtures of a) compounds which can be polymerized by UV irradiation with at least one polymerizable C-C multiple bond or of mixtures containing such compounds with b) monoketals of aromatic 1,2-diketones as photoinitiators according to patent (patent application P 22 32 365.5), characterized in that they are monoketals of aromatic 1,2-diketones non-cyclic asymmetrical monoketals of the formula 1 ? ACCA
»/ \ 0 O ₁ O ₃ R R 1 2 A and A are identical or different, if appropriate, substituents contain, in which mean
same or different carrying aromatic residues, 1 2 R and R optionally have substituents-bearing hydrocarbon radicals 1 2 1 to 12 carbon atoms and R and R different radicals represent. BASF Aktiengesellschaft 7098U / 012? ORIGINAL INSPECTED