DE1769853C3 - Compounds that can be polymerized by UV irradiation - Google Patents

Description

H ₂ COR Ar-C-C-Ar

Il I

O Ο — Η

contain, in which Ar is an aromatic radical which may be substituted by alkyl, alkoxy and / or halogen, and R is hydrogen, alkyl or acyl stand.

30th

35

The present invention relates to UV irradiation polymerizable compounds which contain at least one activated carbon-carbon double bond, and mixtures thereof with a content of benzoins substituted in the «position.

Compounds which initiate and accelerate photopolymerization have been mentioned in the literature, inter alia. one called a large number of sulfur and halogen-containing compounds. Benzoin (US-PS 23 67 661) and some benzoin derivatives, such as certain «-substituted benzoins - where the substituent is a monovalent hydrocarbon radical with 1 to 9 carbon atoms is - (US-PS 27 22 512) and benzoin ether primary alcohols (US-PS 24 48 828, FR-PS 14 50 589).

None of these connections has been able to establish itself technically. The main reasons for this are the to low reactivity and the inadequate dark storage stability of those treated with these photosensitizers polymerizable compounds.

A group of -substituted benzoins has now been found, their mixtures with polymerizable Compounds and mixtures do not have the disadvantages mentioned. These are in the dark Excellent storage stability and polymerize quickly when exposed to UV rays.

The invention therefore relates to UV irradiation curable compositions of polymerizable compounds or mixtures with a content of «-Substituted benzoins as photoinitiators, which are characterized in that they are benzoins formula

H ₂ COR Ar-C-C-Ar

O O - ll

contain, in which Ar is an aromatic radical which may be substituted by alkyl, alkoxy and / or halogen kariri. and R for hydrogen, alky! or acyl.

45

50

55 Examples of such compounds are: "-hydroxymethyl benzoin," -hydroxymethyl ^ '- dimethyl-benzoin (mp 84-87 ° C.), A-HydroxymethyM ^' - dichlorbenzoin (m.p. 330-132 ⁰ C.), A -HydiOxymethyI-4,4'-dimethoxy benzoin (mp. 8I ⁰ C), "-Acetoxymethyl-benzoin (mp. 99-101 ⁰ C). The easily accessible -hydroxymethyl-benzoin proved to be particularly advantageous.

These compounds can by reacting the corresponding benzoins in aqueous alcohol with Formaldehyde can be produced in a known manner in the presence of alkalis (see A. Kuzin, Chem. Ben 68, 2169 [1935J. Esterifications and Etherifications of the methylol group can follow, with the possible reaction components the photopolymerizable substrates themselves can also be used.

The benzoins are expediently in amounts of about 0.1 to about 5 percent by weight, preferably from about 0.5 to about 2.5 weight percent, either alone or in admixture with one another, is used

All substances with carbon-carbon double bonds are suitable as polymerizable compounds by z. B. halogen atoms or carbonyl, cyanide, carboxy, ester, amide, ether or aryl groups and carbon double and carbon triple bonds are activated. Examples are: Vinyl chloride, vinylidene chloride, vinyl methyl ketone, acrolein, acrylic acid methyl ester, methacrylic acid ethyl ester, Acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, chloroprene, vinyl ethyl ether and styrene.

Molding and coating compositions can be stabilized in the usual way with particular advantage Use mixtures of unsaturated polyesters and polymerizable monomeric compounds, with among unsaturated polyesters, as usual, polycondensation products from "^ -unsaturated dicarboxylic acids, such as maleic acid, fumaric acid, itaconic acid, mesaconic acid and citraconic acid, with polyols such as ethylene glycol, diethylene glycol, propane, butane, hexanediol, Trimethylolpropane and pentaerythritol are to be understood. Some of the unsaturated acids can be replaced by saturated, for example succinic acid, glutaric acid, adipic acid, phthalic acid, tetrachlorophthalic acid, hexachloroendomethylene tetrahydrophthalic acid and trimellitic acid. Further modifications are possible by incorporating monohydric alcohols such as butanol, Butyl glycol and tetrahydrofurfuryl alcohol, as well as by incorporating monobasic acids such as benzoic acid, oleic acid, Linseed oil fatty acid and ricine fatty acid. Also so-called air-drying molding compounds, which apart from the leftovers «, ^ - unsaturated dicarboxylic acids nor / ^ - unsaturated Contain ether residues, be it as components of the polyester, for example according to DT-AS 10 24 654, be it as Part of other mixture components, for example according to DT-PS 10 67 210 and 10 81222, can be used.

Polymerizable monomeric compounds include the unsaturated ones customary in polyester technology Compounds with optionally substituted vinyl in the position or substituted in the position Allyl groups, e.g. B. styrene, vinyl toluene, divinylbenzene, vinyl acetate, acrylic acid and its esters, acrylonitrile, Methacrylic acid and its corresponding derivatives and allyl esters, such as allyl acetate, allyl acrylate, diallyl phthalate, Triallyl phosphate and triallyl cyanurate.

The photopolymerizable compounds or

Mixtures can by adding common inhibitors, such as p-benzoquinone, hydroquinone, 3-MethyIbrenzcatechin or copper compounds, z. B. copper naphthenate, be stabilized in the known amounts and contain other usual additives. If necessary, can also Polymerization catalysts, e.g. B. peroxides, in quantities from about 0.1 to about 4 percent by weight can also be used. Suitable peroxides are e.g. B. tert-butyl perbenzoate, dicumyl peroxide, benzoyl peroxide, lauroyl peroxide, especially methyl ethyl ketone peroxide and Cyclohexanone peroxide. Furthermore, the use of peroxides, namely methyl ethyl ketone peroxide, primarily to be recommended when it is desired to have slight discolouration of the hardening products, such as they can occur through exposure to light during irradiation, but under certain circumstances also during storage, turn off.

In connection with the use of ketone peroxides can accelerate the hardening Metal compounds such as cobalt, zirconium and vanadium naphthenate, or metal chelates such as cobalt and Zirconium acetyiacetonate. With the simultaneous presence of peroxides and metal accelerators, however, the storage stability of the masses is It is therefore advisable to use the so-called To work with the active base method, in which the coating compound is applied to a previously applied, peroxide-containing layer is applied.

It is particularly advantageous to use the benzoins to be used according to the invention in such coating compositions apply to which paraffin or wax or waxy substances are added, which at the beginning of the Float out of polymerization and prevent the inhibiting effect of atmospheric oxygen.

To protect light-sensitive surfaces, e.g. B. light woods, the molding and coating compositions small amounts of conventional UV absorbers can be added without the reactivity significantly is affected. Furthermore, small amounts of customary carriers and fillers as well as thixotropic agents such as glass fibers, synthetic fibers, silica and talc, be present during the photopolymerization.

As radiation sources for carrying out the photopolymerization, natural sunlight or Artificial emitters, the emission of which is in the range of 250-500 nm, preferably 300-400 nm, are used. For example, mercury vapor, Xenon and tungsten lamps. Even under the ultraviolet and visible radiation from low energy

ίο fluorescent lamps with an emission of 300-580 nm the compositions according to the invention cure rapidly to form almost colorless molded and coated parts.

The production of molded parts from the compositions sensitized according to the invention is particularly effective advantageous from the fact that the masses by appropriately dosed irradiation without any noticeable exothermicity can be cured, whereby even larger molded parts can be obtained crack-free. In the absence of Peroxides and metal accelerators can harden possibly also interrupted by darkening and after the prepolymers obtained in this way have been stored, they can be completed at any time.

example 1

An unsaturated polyester made by condensing 152 parts by weight of maleic anhydride, 141 parts by weight of phthalic anhydride and 195 parts by weight of 1,2-propanediol are mixed with 0.045 parts by weight of hydroquinone and 65 weight percent in Dissolved styrene

2 parts by weight of known photosensitizers, on the other hand, of photosensitizers according to the invention are added to every 100 parts by weight of this resin delivery form, and the mixtures are stored at 60 ° C. with the exclusion of light until they gel. In Table 1, sensitizers and the values of the storage stability are contained at 6O ⁰ C.

Table 1

Dark storage stability of the delivery form of a typical polyester resin with an additive of 2 parts by weight of sensitizer

Sensitizer Storage stability at 60 ° C

Benzoin

Benzoin ethyl ether

Λ-hydroxymethylbenzoin

«-Hydroxymethyl-4,4'-dichlorobenzoin

<x -hydroxymethyl-4,4'-dimethoxybenzoin

Λ-acetoxymethylbenzoin

less than 1 day less than 1 day 7-8 days longer than 10 days 6 - 7 days longer than 10 days

Example 2

In each case 100 parts by weight of the resin delivery form described in Example 1 become 20 parts by weight Styrene, 1 part by weight of a 10% strength by weight solution of paraffin (melting point 52-53 ° C.) in toluene and on the one hand known photosensitizers according to the invention, on the other hand, admixed in equimolar amounts. The solutions obtained in this way are brought with you a film puller (500 μπι) on glass plates and exposed with the radiation of a fluorescent lamp (Osram-L 40 W / 70-1) at a distance of 5 cm.

Table 2 shows the paraffin swim-out times and the times to reach pencil hardness > 6 H included.

Table 2

Sensitizer Addition in Swim out pencil Parts by weight, time of hardness> 6H related to Paraffins after min HarJieferform after min Benzoin 2.12 23 14.0 Λ-methylbenzoin 2.26 13th α-phenylbenzoin 2.88 1.3 133 Benzoin ethyl ether 2.40 0.63 53 α-hydroxymethyl benzoin 2.42 0.80 6.0 «-Hydroxymethyl-4,4'-dichlorobenzoin 3.11 0.95 6.0 Λ-acetoxymethyl benzoin 2.71 1.0 73

Example 3

A mixture each of 100 parts by weight of the resin delivery form described in Example 1, 20 parts by weight of styrene and 1 part by weight of a 10 weight percent A solution of paraffin (melting point 52-53 ° C.) in toluene is mixed with 2 parts by weight of -hydroxymethyl-benzoin and additionally with a peroxide and / or a metal compound or with a UV absorber or a peroxide and a UV absorber are added

500 μπι thick layers of these solutions are with a film puller applied to glass plates and the radiation described at a distance of 5 cm Fluorescent lamp exposed The paraffin float times and the times until the pencil hardness> 6 H is reached are contained in Table 3.

Table 3

Weight percentages

Additions, based on the form of resin delivery

Swim times Pencil hardness of paraffin > 6H after min after min 1.4 8th 1.3 9 8th 1.9 133

4 cyclohexanone peroxide (50% in plasticizer)

4 methyl ethyl ketone peroxide (40% in plasticizer)

2 cobalt naphthenate solution (20% in toluene)

4 methyl ethyl ketone peroxide (40% in plasticizer)

2 cobalt naphthenate solution (20% in toluene)

0.05 flt-cyano-ß- (4-methoxyphenyl) -methacrylic acid-

butyl ester
4 methyl ethyl ketone peroxide (40% in plasticizer)

0.25 2-hydroxy-4-methoxybenzophenone 3.0

1.7

14th

14th

Example 4

An active primer is applied to wood from a solution of 50 g of nitrocellulose solution (20 percent by weight in Ethyl acetate), 18 g of butyl acetate, 20 g of methyl ethyl ketone peroxide (40 percent by weight in plasticizer) and Ethyl acetate, which was made up to 100 ml, applied in a layer thickness of 100 μm. After Evaporation of the solvent in each case a layer thickness of 500 μπι (a) a polyester resin mixture, consisting of 100 parts by weight of resin delivery form, as described in Example 1, 20 Parts by weight of styrene, 1 part by weight of 10 weight percent Solution of paraffin (melting point 52-53 ° C) in toluene, 2 Parts by weight of hydroxymethylbenzoin and (b) a polyester resin mixture according to (a) to which 2 parts by weight of cobalt naphthenate solution are added, and (c) a polyester resin mixture according to (a), which also contains 2 parts by weight of cobalt naphthenate and 0.1 parts by weight of a UV absorber are added, applied and after a ventilation time of 3 minutes with the described fluorescent lamp irradiated at a distance of 5 cm The description of the additives and the The results of the polymerization are shown in Table 4.

Table 4

Weight
percentages

Additions, based on resin delivery info

Swimming times pencil hardness of paraffin> 6H

after min after min

a) without addition 1.4

b) 2 colloidal naphthenate solution (2O% in toluene) 2,3

c) 2 colloidal naphthenate solution (20% in toluene) 4.2 0.1 a-cyano - ^ - (4-methoxyphenyl) -methacrylic acid-

butyl ester

10.5

13th

15.5

Example 5

An unsaturated polyester prepared by condensing 1765 parts by weight of maleic anhydride, 756 parts by weight of ethylene glycol, 405 parts by weight of 1,3-butanediol and 1540 parts by weight of trimethyloipropanediallyl ether in the presence of 0.83 parts by weight of hydroquinone becomes TO weight percent in Dissolved styrene.

After adding 1 part by weight of cobalt naphthenate solution per 100 parts by weight of this delivery form (20 percent by weight in toluene) with various

Sensitizers according to the invention added.

The solutions are each as 500 μm thick Layer on glass at a distance of 5 cm from the fluorescent lamp described above is exposed until The film has gelled. The prepolymer is then exposed to radiation from a high-pressure mercury vapor burner (Philips HPK 125 W / L) at a distance of 10 cm exposed until the surface of the coating is tack-free. The pencil hardness is then > 6 H.

The times required for gelation under the fluorescent lamp and for curing are in the Table 5 included.

Table 5

Weight percentages

Addition based on the form of resin delivery

Gelation under the Fluorescent tube

after min

Through hardening under High pressure mercury burner, Pencil hardness> 6 H after min

2 Λ-hydroxymethylbenzoin 0.8

2 α-hydroxymethyl-4,4'-dichlorobenzoin 0.8

2 Λ-acetoxymethyl-benzoin 1.0

6th 6th 6th

Example 6

10 g of freshly distilled acrylic acid methyl ester will be mixed with 0.1 g of Λ-hydroxymethylbenzoin. The exposure takes place at a distance of 10 cm with a Mercury vapor high pressure burner (Philips HPK 125 W / L) through quartz in a water bath of 24 ° C. The solution of the sensitizer in the monomer is in a nitrogen atmosphere in a quartz glass, the inner diameter of which is 1.7 cm Exposure time is 2 '/ 2 minutes. Immediately after exposure, the quartz glass is placed in a mixture of ice and table salt in order to allow thermal polymerization impede. The solution of the polymer in the monomer including the solid polymer fractions that aul the inside of the quartz (on the side facing the high pressure mercury vapor burner) is mixed with small amounts of a solvent (Methylene chloride) rinsed into a small round-bottomed flask. Then use a rotary evaporator unpolymerized monomeric fractions and the solvent is distilled off Residue in the vacuum drying cabinet to weight The amount of polymer is constant at 60 ° C determined it is 13.6 percent by weight. If the sensitizer is not present, the amount of polymer is less than 0.1 percent by weight

Claims (1)

Claim: UV-curable masses made of polymerizable Compounds or mixtures with a content of -substituted benzoins as Photoinitiator and, if necessary, additional peroxide catalysts, metal accelerators, inhibitors, UV absorbers, carriers and fillers, thixotropic agents and / or paraffin or wax or waxy substances, characterized in that that they are compounds of the formula