CH682666A5 - New alkyl-bis-acyl-phosphine oxide photoinitiators - Google Patents

Abstract

A cpd. of formula (I) is claimed. In (I), R1 is 1-18C alkyl, cyclopentyl or cyclohexyl; R2 and R3 are each phenyl, unsubstd. or carriers 1, 2, 3 or 4 substituents from halogen, 1-4C alkyl and 1-4C alkoxy; and R1 is not decyl if R2 and R3 are halogen-substd. phenyl. Also claimed is (1) a compsn. comprising (a) at least one ethylenically unsatd. photopolymerisable cpd. and (b) at least one cpd. of formula (I) as photoinitiator; and (2) a process for the photopolymerisation of a cpd. wherein the above compsn. is exposed to light in the range from 200-600nm.

Description

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description

The invention relates to bisacylphosphine oxides and compositions containing these compounds as photoinitiators.

Mono- and bisacylphosphine oxides are known as photoinitiators.

EP-A 184 095 describes bisacylphosphine oxides which are used as photo hardeners for dental compositions.

EP-A 262 629 shows the use of bisacylphosphine oxides in aqueous-alkaline developable compositions for the production of printing plates and relief forms.

Further mono- and bisacylphosphine oxide photoinitiators are published in EP-A 413 657.

For the extensive field of application of photoinitiators, there is still a need for effective, easy to manufacture photoinitiators.

It has been found that certain bisacylphosphine oxide compounds with alkyl radicals on the phosphorus are effective photoinitiators. The invention thus relates to compounds of the formula I

o o o

R2-C-P-C - Rg R1

in which Ri is Ci-Cis-alkyl, cyclopentyl or cyclohexyl, and R2 and R3 independently of one another are unsubstituted or mono- to tetrasubstituted by halogen, Ci-C4-alkyl and / or C-KU-alkoxy, with the proviso that that when R2 and R3 are phenyl substituted with halogen, Ri is not decyl.

Ri as Ci-Ci8-alkyl can be linear or branched and means, for example, methyl, ethyl, n-propyl, iso-propyl, n-butyl, iso-butyl, sec-butyl, tert-butyl, pentyl, hexyl, heptyl, octyl , 2,4,4-trimethyl-pent-1-yl, 2-ethylhexyl, nonyl, decyl, dodecyl or octadecyl.

R2 and R3 as phenyl substituted once to four times with halogen, Gi-C4-alkyl and / or Ci-C4-alkoxy mean, for example, chlorophenyl, dichlorophenyl, tetrachlorophenyl, tolyl, dimethylphenyl, mesityl, tetramethylphenyl, ethylphenyl, diethylphenyl, triethylphenyl, methyl Ethylphenyl, dimethylethylphenyl, methoxyphenyl, dimethoxyphenyl, trimethoxyphenyl, dimethoxymethylphenyl, methoxymethylphenyl, dimethylmethoxyphenyl, ethoxyphenyl, diethoxyphenyl, diethoxymethylphenyl, propyloxyphenyl, butoxy-phenyl, dibutoxyphenyl, butoxymethoxyethoxyphenyl, preferably oxymethoxyethoxyphenyl, ethoxymethoxyphenoxyphenyl, ethoxymethoxyphenoxy, preferably ethoxymethoxyphenyl, ethoxymethoxyphenyl, ethoxymethyloxyphenyl, ethoxymethoxyphenyl, ethoxylphenyl *

R2 and R3 are one to four times, preferably one to three times, in particular two or three times phenyl substituted with halogen, Ci-C4-alkyl and / or Cr-C4-alkoxy.

Halogen represents fluorine, chlorine, bromine and iodine, especially chlorine.

Compounds of the formula I in which R2 and R3 are identical are preferred.

Interesting compounds of the formula I are those in which Ri is Ci-Ci2-alkyl, in particular Cr-Cs-alkyl or cyclohexyl and R2 and R3 are phenyl substituted with chlorine, Ci-C4-alkyl and / or Ci-C4-A! Koxy .

Compounds of the formula I are important in which R 1 is cyclopentyl, cyclohexyl, Cr-Cs-alkyl or C12-C18-alkyl and R 2 and R 3 are phenyl substituted by halogen.

Also of interest are compounds of the formula I in which R 1 is C 4 -C 8 -alkyl or cyclohexyl.

Other preferred compounds of formula I are those in which R2 and R3 represent 2,6- or 2,4,6-position substituted phenyl.

Preference is given to compounds of the formula I in which R2 and R3 are phenyl which is substituted by Ci-C4-alkoxy, in particular methoxy, and / or Ci-C4-alkyl, in particular methyl.

Other interesting compounds of the formula I are those in which R2 and R3 are phenyl substituted by C-KVAIkoxy, in particular methoxy.

The compounds according to the invention can e.g. are produced by double acylation of a primary phosphine VI with at least 2 equivalents of an acid chloride V in the presence of at least 2 equivalents of a base and subsequent oxidation of the diacylphosphine IV obtained to the phosphine oxide according to the scheme:

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CH 682 666 A5

O II

2 R2-C-CI (V)

+ HgP-Rj (VI)

base

(O

-► Rrp..c_r2

(IV)

oxidation

OOO

The unsymmetrical compounds of the formula R2-C - P-C - R3 (j) are obtained by

Ri one equivalent of an acid chloride (V) and

O

II

Rg-C-Cl

(Va) begins.

Suitable bases are e.g. tertiary amines, alkali metals, lithium diisopropylamide, alkali alcoholates or alkali hydrides. The first reaction stage is preferably carried out in solution. Hydrocarbons are particularly suitable as solvents, e.g. Alkanes, benzene, toluene or xylene. After the base chloride formed has been separated off, the phosphine (IV) can be isolated by evaporation or the second reaction stage is carried out without isolating (IV) with the solution of the crude product. Particularly suitable oxidants for the second stage are hydrogen peroxide and organic peroxy compounds, for example peracetic acid or air.

The primary phosphines (VI) used as starting material are known, some commercially available compounds or can be prepared in analogy to known compounds (see Houben-Weyl, Methods of Org. Chemie XII / 1, 60-63 (1963), G Thieme publishing house, Stuttgart). The acid chlorides of the formula (V) or (Va) are also prepared by known methods from the prior art.

According to the invention, the compounds of formula I can be used as photoinitiators for the photopolymerization of ethylenically unsaturated compounds or mixtures which contain such compounds. The unsaturated compounds can contain one or more olefinic double bonds. They can be low molecular weight (monomeric) or higher molecular weight (oligomeric). Examples of monomers with a double bond are alkyl or hydroxyalkyl acrylates or methacrylates, such as e.g. Methyl, ethyl, butyl, 2-ethylhexyl or 2-hydroxyethyl acrylate, isobornyl acrylate, methyl or ethyl methacrylate. Further examples of this are acrylonitrile, acrylamide, methacrylamide, N-substituted (meth) acrylamides, vinyl esters such as vinyl acetate, vinyl ethers such as isobutyl vinyl ether, styrene, alkyl and halogenstyrenes, N-vinyl pyrrolidone, vinyl chloride or vinylidene chloride.

Examples of monomers with several double bonds are ethyl glycol, propylene glycol, neopty-tyl glycol, hexamethylene glycol or bisphenol A diacrylate, 4,4'-bis (2-acryloyloxyethoxy) diphenylpropane, trimethylolpropane triacrylate, pentaerythritol or triacrylate tetraacrylate, pentaerythritol divinyl ether, vinyl acrylate, divinylbenzene, divinyl succinate, diallyl phthalate, triallyl phosphate, triallyl isocyanurate or tris (2-acryloylethyl) isocyanurate.

Examples of higher molecular weight (oligomeric) polyunsaturated compounds are acrylated epoxy resins, acrylated polyethers, acrylated polyurethanes or acrylated polyesters. Further examples of unsaturated oligomers are unsaturated polyester resins, which are usually produced from maleic acid, phthalic acid and one or more diols and have molecular weights of approximately 500 to 3000. Such unsaturated oligomers can also be referred to as prepolymers.

Two-component mixtures of a prepolymer with a polyunsaturated monomer or three-component mixtures which also contain a monounsaturated monomer are frequently used. The prepolymer is primarily decisive for the properties of the lacquer film; through its variation, the person skilled in the art can influence the properties of the hardened film. The polyunsaturated monomer acts as a crosslinker, which makes the paint film insoluble. The monounsaturated monomer acts as a reactive diluent that lowers the viscosity without the use of a solvent.

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Such two- and three-component systems based on a prepolymer are used both for printing inks and for lacquers, photoresists or other photocurable compositions.

Unsaturated polyester resins are mostly used in two-component systems together with a monounsaturated monomer, preferably with styrene. Specific one-component systems are often used for photoresists, e.g. Polymaleimides, polychalcones or polyimides as described in DE-OS 2 308 830.

The unsaturated compounds can also be used in a mixture with non-photopolymerizable film-forming components. These can e.g. physically drying polymers or their solutions in organic solvents, e.g. Nitrocellulose or cellulose acetobutyrate. However, these can also be chemically or thermally curable resins, e.g. Polyisocyanates, polyepoxides or melamine resins. The use of thermally curable resins is important for use in so-called hybrid systems, which are photopolymerized in a first stage and crosslinked in a second stage by thermal aftertreatment.

In addition to the photoinitiator, the photopolymerizable mixtures can contain various additives. Examples of this are thermal inhibitors which are intended to prevent premature polymerization, e.g. Hydroquinone or hindered phenols. To increase dark storage stability, e.g. Copper compounds, phosphorus compounds, quaternary ammonium compounds or hydroxylamine derivatives are used. To exclude atmospheric oxygen during the polymerization, paraffin or similar wax-like substances can be added, which migrate to the surface at the start of the polymerization. Small amounts of UV absorbers such as e.g. those of the benzotriazole, benzophenone or oxalanilide type can be added. It is even better to add light stabilizers that do not absorb UV light, e.g. of sterically hindered amines (HALS).

Amines can be added to accelerate the photopolymerization, e.g. Triethanola-min, N-methyl-diethanolamine, p-dimethylaminobenzoic acid ethyl ester or Michler's ketone. The effect of the amines can be enhanced by the addition of aromatic ketones of the benzophenone type. The photopolymerization can also be accelerated by adding photosensitizers which shift or broaden the spectral sensitivity. These are especially aromatic carbonyl compounds such as Benzophenone, thioxanthone, anthraquinone and 3-acylcoumarin derivatives as well as 3- (aroylmethylene) thiazolines.

Depending on the intended use, other common additives are fillers, pigments, dyes, wetting agents or leveling agents.

The invention therefore also relates to photopolymerizable compositions comprising (a) at least one ethylenically unsaturated photopolymerizable compound and (b) at least one compound of the formula I as photoinitiator, the composition also being able to contain another photoinitiator and / or other additives.

The photopolymerizable compositions advantageously contain the photoinitiator (b) in an amount of 0.05 to 15% by weight, preferably 0.2 to 5% by weight, based on the composition.

In certain cases it may be advantageous to use mixtures of two or more of the photoinitiators according to the invention. Of course, mixtures with known photoinitiators can also be used, e.g. Mixtures with benzophenone, acetophenone derivatives, benzoin ethers or benzil ketals.

The invention therefore also relates to compositions in which the additional photoinitiators are compounds of the formula II

FU for hydrogen, Ci-Cis-alkyl, Ci-Cis-alkoxy, -OCH2CH2-OR8, a group ch3

1

CH3I

CH2 = C or a group in which g

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O R5

M 1

n has a value from 2 to 10 and G for the rest

—C —C - OR7 is r6

Rö and R6 independently of one another denote hydrogen, Cr-C6-alkyl, phenyl or Ci-C4-aikoxy, or R5 and R6 together with the carbon atom to which they are attached form a cyclohexyl ring,

R7 represents hydrogen or CHIU-Aikyl and o o ch3

I! II I

R8 denotes hydrogen, - C - CH = CH2 or C - C = CH2,

and / or of formula III

R11O

Rg, R10 and R11 are independently hydrogen or methyl, or are mixtures thereof.

R4 as Ci-Ci8-alkyl can have the same meanings as described for Ri. R5 and R6 as Ci-C6-alkyl and R7 as Ci-C4-alkyl can also have the same meanings as described for Ri, up to the respective number of C atoms.

R4 as Ci-Ci8-alkoxy means, for example, branched or unbranched alkoxy such as e.g. Me-thyoxy, ethoxy, n-propyloxy, iso-propyloxy, n-butyloxy, iso-butyloxy, sec-butyloxy, tert-butyloxy, pentylene, hexyloxy, heptyloxy, octyloxy, 2,4,4-trimethylpent- 1-yloxy, 2-ethylhexyloxy, nonyloxy, decyloxy, dodecyloxy or octadecyloxy.

R5 and Rß as Ci-C4-alkoxy are, for example, methoxy, ethoxy, n-propyloxy, iso-propyloxy, n-butyloxy, iso-butyloxy, sec-butyloxy or tert-butyloxy, preferably methoxy and ethoxy.

Compositions are preferred in which in the formula II R5 and R6 independently of one another denote C1-Cs-alkyl, or together with the carbon atom to which they are bonded, form a cyclohexyl ring and R7 is hydrogen.

Further preferred compositions are those in which the proportion of compounds of the formula I in a mixture with compounds of the formulas II and / or III is 5 to 95%, preferably 30 to 70%.

Compositions are also important in which, in the compounds of the formula I, R is n-butyl, i-butyl or 2,4,4-trimethyl-pent-1-yl, R 2 and R 3 are the same and 2,6-dimethoxyphenyl or 2, 4,6-Tri-methylphenyl mean, and in the compounds of formula II R5 and R6 are the same and stand for methyl and R4 is hydrogen, i-propyl ch3

CH2 = C or a group

Also preferred are compositions containing compounds of the formula I in which R is n-butyl, i-butyl or 2,4,4-trimethyl-pent-1-yl, R2 and R3 are the same and 2,6-dimethoxyphenyl or 2 , 4,6-Trimethylphenyl, and a mixture of compounds of formula III, in which compounds of formula III with R9 and R10 equal to hydrogen and Rh equal to methyl 20% and compounds of formula III with R9, R10 and R11 equal to methyl 80% are included.

Compositions as described above which contain photoinitiator mixtures of the formulas I, II and / or III and are liquid at room temperature are of particular interest.

The preparation of the compounds of the formulas II and III is generally known and some of the compounds are commercially available. The production of oligomeric compounds of formula II is at 5

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described for example in EP-A 0161 463. A description of the preparation of compounds of formula III is e.g. can be found in EP-A 209 831.

The photopolymerizable compositions can be used for various purposes, for example as printing ink, as white lacquer, e.g. for wood, as paint, etc. for paper, wood, metal or plastic, as paint for exterior painting, for photographic reproduction processes, for image recording processes or for the production of printing plates that can be developed with organic solvents or aqueous-alkaline, as dental filling compounds, as adhesives, as etching or permanent resists and as solder masks for printed electronic circuits, for the production of three-dimensional objects by mass hardening (UV hardening in transparent forms) or according to the stereolithography method, as it is eg in U.S. Patent No. 4,575,330, for the manufacture of composite materials (e.g. styrenic polyesters, which may or may not contain glass fibers and other auxiliaries) and other thick-film compositions, for coating electronic parts or as coatings for optical fibers.

Photocuring is of great importance for printing inks, since the drying time of the binder is a decisive factor for the production speed of graphic products and should be in the order of fractions of a second. UV-curable inks are particularly important for screen printing.

The mixtures according to the invention are also very suitable for the production of printing plates. Here, e.g. Mixtures of soluble linear polyamides or styrene / butadiene rubber with photopolymerizable monomers, for example acrylamides, and a photoinitiator are used. Films and plates from these systems (wet or dry) are exposed via the negative (or positive) of the artwork and the uncured parts are then eluted with a suitable solvent. Development can take place both in an organic solvent and in an aqueous alkaline medium.

Another area of application for photocuring is metal coating, for example in the coating of sheets and tubes, cans or bottle closures, as well as photocuring on plastic coatings, for example floor or wall coverings based on PVC.

Examples of the photocuring of paper coatings are the colorless coating of labels, record sleeves or book covers.

It is also important to use photocurable compositions for imaging processes and for the optical production of information carriers. The layer applied to the support (wet or dry) is irradiated with short-wave light through a photomask and the unexposed areas of the layer are removed by treatment with a solvent (= developer). The photocurable layer can also be applied to metal using the electrodeposition process. The exposed areas are cross-linked polymer and therefore insoluble and remain on the support. With appropriate coloring, visible images are created. If the carrier is a metallized layer, the metal can, after exposure and development, be etched away at the unexposed areas or reinforced by electroplating. In this way, printed electronic circuits and photoresists can be produced.

The polymerization is carried out according to the known methods of photopolymerization by irradiation with sunlight or with light which is rich in short-wave radiation. As light sources e.g. Medium-pressure, high-pressure and low-pressure mercury lamps, superactinic fluorescent tubes, metal halide lamps or lasers are suitable, the emission maxima of which are in the range between 250 and 450 nm. In the case of a combination with photosensitizers, longer-wave light or laser beams up to 600 nm can also be used.

The compounds according to the invention are suitable for use in a process for the photopolymerization of compounds having ethylenically unsaturated double bonds, characterized in that a composition as described above is irradiated with light in the range from 200 to 600 nm.

The photoinitiators according to the invention have high reactivity and, when used, paint surfaces with good gloss values are obtained. Because of the low tendency to yellowing, the compounds according to the invention are particularly suitable for use in white lacquers; their ability to harden thick layers enables use in the production of printing plates and composite materials.

The following examples further illustrate the invention. Information in parts or percentages, as in the rest of the description and in the claims, are by weight, unless stated otherwise. In the examples and tables, the abbreviation "ber." for the calculated values of the elementary analyzes, the abbreviation «found.» for the actually determined values.

Example 1;

Preparation of bis (2.4.6-trimethvlbenzovn-isobutvlDhosDhinoxid

140.6 ml (0.225 mol; 1.6 M) of butyllithium are added dropwise to a solution of 31.9 ml (0.225 mol) of diisopropylamine in 80 ml of tetrahydrofuran at 0 ° C. in the course of 30 min. This solution is converted into a solution of 41.1 g (0.225 mol) of 2,4,6-trimethylben- at -30 ° C within 90 min.

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zoyl chloride and 12 ml (0.102 mol) of isobutylphosphine in 200 ml of tetrahydrofuran were added dropwise. After stirring for 2 h at -30 ° C, the yellow solution is allowed to warm to room temperature and washed once with water. The organic phase is dried with magnesium sulfate, filtered and concentrated on a rotary evaporator. The residue is dissolved in 200 ml of toluene and 11.6 g (0.102 mol) of 30% hydrogen peroxide are added. After stirring for 2 h, washing is carried out first with water and then with saturated sodium hydrogen carbonate solution. Then it is dried with magnesium sulfate, filtered off and the solution is concentrated on a rotary evaporator. After crystallization from hexane, 27.8 g (68.5% of theory) of the above compound are obtained as a yellow powder. The melting point is 85-86 ° C. Elemental analysis:

calc.% C 72.34 found % C 72.13 calc.% H 7.84 found % H 7.94

Example 2: Preparation of Bisf2.6-dimethoxvbenzovli-n-butvlDhosDhinoxid

A mixture of 18 g (0.10 mol, 50% in toluene) is added to a solution of 44.1 g (0.22 mol) of 2,6-dimethoxybenzoyichloride in 200 ml of toluene at 100-110 ° C within 60 min ) n-butylphosphine and 30.7 ml (0.22 mol) of triethylamine were added dropwise. After stirring for 6 h at 100-110 ° C, the suspension formed is allowed to cool to room temperature, diluted with toluene and washed first once with water and then once with saturated sodium bicarbonate solution. 11.3 g (0.10 mol) of 30% hydrogen peroxide are added to the organic phase and the mixture is stirred at 40 ° C. for 2 h. It is then washed with water and saturated sodium bicarbonate solution, dried with magnesium sulfate, filtered and concentrated on a rotary evaporator. After crystallization from ethyl acetate, 30.2 g (69.6% of theory) of the above compound are obtained as a yellow powder. The melting point is 151-152 ° C. Elemental analysis:

calc.% C 60.83 found % C 60.84 calc.% H 6.26 found % H 6.35

Examples 3-25:

The compounds of Examples 3-25 are prepared analogously to the compound of Example 1 (= method A) or the compound of Example 2 (= method B). The compounds and their analytical data are shown in Table 1.

fl — p -c

0 / O

I! II

V

7

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Table 1:

5

Example Ri no.

r2

r3

R4

Melting point [° Cj

Synthetic method

Elemental analysis [%]

calc.

3rd

C4H9

ch3

ch3

ch3

58

a c 72.34 72.08

h 7.84 8.01

10th

4th

ch (ch3) c2h5

ch3

ch3

ch3

115

a c 72.34 72.23

h 7.84 7.93

5

c (ch3) 3

ch3

ch3

ch3

160

a c 72.34 72.21

h 7.84 8.06

15

6

Cyclohexyl ch3

ch3

CHs

140

a c 73.56 73.39

h 7.84 8.06

7

CsHl7

chs ch3

ch3

Harz a

c 73.98 73.83

h 8.65 8.89

20th

8th

CH2CH (CH3) CH2c (CH3) 3

ch3

ch3

ch3

Harz a

c 73.98 73.97

h 8.65 8.98

g ch2ch (ch3) 2

OCH3

och3

H

183

B

c 60.83 60.70

h 6.26 6.09

25th

10th

ch2 (ch3) C2H5

OCH3

OCH3

H

159

B

c 60.83 60.75

h 6.26 6.24

11

c (ch3) 3

OCH3

OCH3

H

235

B

c 60.83 60.00

h 6.26 6.17

30th

12th

Cyclohexyl

OCH3

OCH3

H

165

B

c 62.60 62.40

h 6.35 6.39

13

C8H17

OCH3

OCH3

H

118

B

c 63.66 63.36

h 7.19 7.22

35

14

ch2ch (ch3) ch2c (ch3) 3

OCH3

OCH3

H

117

B

c 63.06 63.60

h 7.19 7.04

15

ch (ch3) c2h5

OC2H5

OC2H5

H

resin

B

c 63.66 62.47

h 7.19 7.33

40

16

ch2ch (ch3) 2

OC2H5

OC2H5

H

110

B

c 63.66 63.54

h 7.19 7.02

17th

ch2ch (ch3) 2

OC4H9

OC4H9

H

70

B

c 67.75 67.35

h 8.53 8.49

45

18th

ch2ch (ch3) 2

ch3

ch3

H

54

a c 71.33 71.32

h 7.35 7.54

19th

ch2ch (ch3) 2

ch3

och3

ochs 161

B

c 62.33 62.23

h 6.76 6.76

50

20th

ch2ch (ch3) 2

och3

h h

175

B

c 62.33 62.29

h 6.76 6.86

21st

ch (ch3) c2h5

OCH3

h h

153

B

c 62.33 62.10

h 6.76 6.70

55

60

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Table 1: (continued)

Example No.

ri r2

rs r4

Melting point [° C]

Synthetic method

Elemental analysis [%]

calc.

22

CH2CH (CH3) 2

CI

Cl

H

153

B

C 47.82 47.74

H 3.34 3.25

Cl 31.37 31.28

23

CH (CH3) C2H5

Cl

Cl

H

136

B

C 47.82 47.41

H 3.34 3.53

Cl 31.37 30.62

24th

Cyclohexyl

Cl

Cl

H

182

B

C 50.24 50.56

H 3.58 3.90

Cl 29.66 29.52

25th

C8H17

Cl

Cl

H

100

B

C 51.99 51.87

H 4.56 4.63

Cl 27.90 27.89

Example 26:

Photoinitiator reactivity in a white lacquer

The photoinitiators are used in concentrations of 0.5 and 1% by weight in a white formulation consisting of:

67.5 parts of ®Ebecryl 830 (polyester acrylate from UCB, Belgium)

5.0 parts hexanediol diacryiate

2.5 parts of trimethylolpropane triacrylate and

25.0 parts of rutile-type titanium dioxide (R-TC2) incorporated.

The samples are applied to chipboard with a 100 nm doctor blade and cured with an 80 W / cm medium pressure mercury lamp (Hanovia type) at a belt speed of 10 m / min. The number of runs until the smudge resistance is reached is determined. The pendulum hardness according to König (DIN 53157) of the white lacquer layers hardened in this way is measured immediately after hardening. Then it is exposed under four 40 W lamps (Philips TL 03) and the pendulum hardness is determined again after 15 minutes or 16 hours. The Yellowness Index according to ASTM D 1925-70 is measured after 16 hours.

The pendulum hardness and smear resistance are a measure of the reactivity of the photoinitiator tested: the fewer the number of runs to achieve smear resistance and the higher the values of the pendulum hardness measurement, the more reactive the photohardener. The yellowness index values are a measure of the yellowing: the smaller the values, the less the yellowing of the tested formulation. The measurement results are listed in Table 2 below.

Table 2

Connection from Ex.

Concentration [% by weight]

Number of passes [10 m / min]

Pendulum hardness immediately after 15 min. after 16 h

Yellowness index after 16 h

4th

0.5

5

165

179

185

1.2

1.0

3rd

164

182

197

1.2

7

0.5

6

164

169

178

1.1

1.0

4th

178

184

199

1.2

13

0.5

6

157

160

174

1.4

1.0

4th

158

172

186

1.6

Example 27:

Photoinitiator reactivity in a white lacquer

A Weissiack is prepared from 75 parts of a formulation of 99.5% Roskydal UV 502 A (BAYER, Germany), 0.5% Byk 300 (Byk-Mallinckrodt) and 25 parts of titanium dioxide. The photoinitiators are in the specified concentrations by shaking with balls (at 2 wt .-% photoinitiator) or

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incorporated by stirring at 50 ° C (at 1.5 wt .-% photoinitiator). The formulation is then applied to chipboard with a 150 fim splitting knife and pre-exposed for 1.5 minutes under four 40 W lamps (Philips TL 03). Further curing takes place in two exposure variants: a) The samples are exposed twice at a belt speed of 10 m / min under an 80 W / cm medium pressure mercury lamp (Hanovia type), b) The samples are under twice at a belt speed of 3 m / min a 20 W / cm Fusion D and an 80 W / cm medium pressure mercury lamp (Hanovia type), which are arranged one behind the other, hardened.

The König pendulum hardness (Din 53157) of the hardened layers is measured immediately, after 15 minutes and 16 hours of post-exposure under 40 W lamps (Philips TL 03). The higher the values, the better hardened the formulation. The yellowness (yellowness index; Yl) of the layers is determined after 16 h after exposure in accordance with ASTM D1925-70. The lower the values, the less yellowing of the layer. The results of the irradiation variant a) are shown in Table 3. The results of the irradiation variant b) are shown in Table 4.

Table 3 (radiation variant a))

Connection from Ex.

Concentration [% by weight]

Pendulum hardness

Yellowness index

immediately after 15 min after 16 h after 16 h

4th

1.5

108

130

179

1.0

2.0

115

147

179

1.0

6

1.5

113

130

182

0.8

2.0

120

154

188

1.0

Table 4 (radiation variant b))

Connection from Ex.

Concentration [% by weight]

Pendulum hardness

Yellowness index after 16 h

immediately after 15 min after 16 h after 16 h

4th

1.5

150

153

179

1.1

2.0

160

165

167

1.1

6

1.5

151

158

181

1.0

2.0

165

170

176

1.1

Example 28:

Photoinitiator reactivity in a white lacquer A photopolymerizable composition is prepared from:

13.5 parts of ®Ebecryl 830 (polyester acrylate from UCB, Belgium)

0.5 parts trimethylolpropane trisacrylate (Degussa)

1.0 parts 1,6-hexanediol diacrylate (Röhm)

5.0 parts of titanium dioxide (rutile type, ®R-TC 2 from Tioxide, France).

Mixtures of the photoinitiator from Example 14 (A) with 1-benzoyl-1-hydroxy-1-methylethane (B) are mixed into this composition in the amounts shown in Table 5. The formulation is applied in a layer thickness of 100 μm to aluminum sheets and the samples thus obtained are irradiated with a medium-pressure mercury lamp (80 W / cm, type: Hanovia). The samples are so often placed on a belt which is moved at a speed of 10 m / min runs under the lamp until a smudge-proof lacquer layer has formed. The fewer the number of runs (n), the better the effect of the tested photoinitiators or photoinitiator mixtures. The yellowing of the samples is called the yellowness index according to ASTM D 1925- 70. The smaller the value, the lower the yellowing of the sample. The yellowing is immediately after curing, after an additional exposure of 15 min and after an additional curing of 16 h under 4 lamps of type TL 40/03 (40 W; Philips) and the results are summarized in Table 5.

10th

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

CH 682 666 A5

Table 5

connection

Concentration [% by weight]

Number of runs [10 min / min]

Yellowness index immediately after 15 min after 16 h

A

0.5

8th

1.0

1.0

-0.7

A

1.0

5

1.9

2.3

-0.5

A

1.5

4th

3.3

4.2

-0.1

A

2.0

3rd

4.1

5.9

-0.2

A

0.5

4th

0.8

1.0

-1.2

B

0.5

A

0.75

3rd

1.6

1.7

-0.6

B

0.75

A

1.0

2nd

1.8

3.1

-0.8

B

1.0

A

0.65

4th

1.3

1.6

-0.9

B

0.35

A

1.0

3rd

1.1

0.8

-1.4

B

0.5

A

1.3

2nd

2.9

4.2

-0.2

B

0.7

A

0.35

4th

0.8

0.7

-0.8

B

0.65

A

0.5

4th

0.7

0.8

-1.2

B

1.0

A

0.7

2nd

1.9

2.2

-0.6

B

1.3

Example 29:

Production of a flexoaraphic printing plate a) 1.13 parts ®lrganox 565 (antioxidant; Ciba-Geigy, Switzerland), 0.03 parts ®Ceres Black (pigment, Sudan Black No. 86015; Fluka, Switzerland) and 0.6% of the testing photoinitiators are at max. 50 ° C with stirring for 30 minutes in 41.54 parts of 1,6-hexanediol diacrylate (HDDA). 332.30 parts of ®Cariflex TR 1107 (block polymer made of polyisoprene and polystyrene; Shell Chemie, Netherlands) are melted with a 2 g excess on the calender for 10 min at 140 ° C. to form a sheet. The dropping of the previously prepared HDDA solution is started at 110 ° C. The dropping takes about 15 minutes. Then the entire formulation is homogenized for a further 15 minutes at 100 ° C. on the quay machine. After removal from the calender, the coarse file is placed between two Teflon foils and cooled in a water-cooled press at a pressure of 100 kp / cm2. 70 g of the skin are enclosed in a 2 mm thick press frame between two 76 mm polyester films and pressed into 2 mm thick plates by first heating the "sandwich" for one minute without applying pressure between the surfaces of a second press preheated to 90 ° C and then pressed for 10 min at a pressure of 200 kp / cm2. The «sandwich» is then cooled in the first press, which is water-cooled to 15 ° C, for 10 min at a press pressure of 200 kp / cm2 and then cut out of the press frame.

b) Now a strip of 4 x 24 cm is cut off from the plate covered with polyester film on both sides to determine the optimal exposure time for the base formation. This strip is exposed gradually by moving a mask between 9 exposure steps of 20 s each in a BASF Nylo-print imagesetter with 20 W Nyloprint 2051 tubes. A hardening pattern of ten sections is created on the strip, which corresponds to the exposure times 0, 20, 40, 60, 80, 100, 120, 140, 160 and 180 s. The plate is turned over and a 1.5 cm wide central stripe in the longitudinal direction

11

5

10th

15

20th

25th

30th

35

40

45

50

55

CH 682 666 A5

covered. The entire structure is covered with a thin UV-transparent film, vacuumed onto the exposure table and exposed for 6 minutes. The exposed plate is developed by washing out the insufficiently cross-linked areas in the BASF Nyloprint circular washer at 20 ° C with a washing solution made from a 4: 1 mixture of tetrachlorethylene and n-butanol. 5 minutes after drying for one hour at 80 ° C. in a forced air oven, the plate is immersed in a 0.4% bromine solution for fixation and immersed in an aqueous solution of 1.15% sodium thiosulfate / sodium carbonate for 10 s. It is then rinsed with deionized water for 30 s. The median strip of the plate treated in this way is evaluated. The exposure time is determined, which leads to the formation of a 1400 μm base (= back exposure time).

c) A piece of a plate sandwich produced as under a) is exposed over the entire area with the exposure time determined under b) to form a plate base. The plate is then turned over, the polyester film is removed and a test negative with 4 fields is applied. The exposure of the 4 test fields of the test negative takes place gradually using a sliding mask. The first field is exposed for 6 minutes, the exposure time of fields 2-4 is increased by one minute each. The plate is developed and fixed as described above. The plate is then exposed over the entire area for a further 6 minutes on both sides. The exposure time is determined to achieve a tonal value of 2% (= front exposure time). The results are shown in Table 6.

Table 6

connection

Back exposure time

Front exposure time from Ex.

[s]

to tone value = 2% [min]

1

80

7

8th

80

8th

Claims (1)

Claims 1. Compounds of formula I. 0 0 0 R2-C -P-C-R3 R1 in which Ri is Ci-Ci8-alkyl, cyclopentyl or cyclohexyl, and R2 and R3 independently of one another represent unsubstituted or mono- to tetrasubstituted by halogen, Ci-C4-alkyl and / or Ci-C4-alkoxy, with the proviso that that when R2 and R3 are phenyl substituted with halogen, Ri is not decyl. 2. Compounds according to claim 1, wherein R2 and R3 are the same. 3. Compounds according to claim 2, wherein Ri is Ci-Ci2-alkyl, in particular Ci-Cs-alkyl or cyclohexyl and R2 and R3 are phenyl substituted with chlorine, Ci-C4-alkyl and / or Ci-C4-alkoxy. 4. Compounds according to claim 2, wherein Ri is cyclopentyl, cyclohexyl, Ci-Cs-alkyl or Ci2-Ci8-alkyl and R2 and R3 are halogen-substituted phenyl. 5. Compounds according to claim 2, wherein R2 and R3 in the 2,6- or 2,4,6-position are substituted phenyl. 6. Compounds according to claim 2, wherein R2 and R3 are substituted by Ci-C4-alkoxy or / and Ci-C4-alkyl phenyl. 7. Containing composition (a) at least one ethylenically unsaturated photopolymerizable compound and (b) at least one compound of the formula I as defined in claim 1 as photoinitiator. 8. The composition according to claim 7, which in addition to component (b) also contains other photoinitiators and / or additives. 9. The composition of claim 7, containing 0.05-15, in particular 0.2-5 wt .-% of component (b), based on the composition. 10. The composition of claim 8, wherein the additional photoinitiators compounds of formula II 12th 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65 CH 682 666 A5 O Re r. I—? - ° R? r « R4 for hydrogen, Cr-Cis-alkyl, Ci-Cis-alkoxy, -OCH2CH2-OR8, a group çh3 CH2 = C or a group ÇH3 îHo - C- where n has a value from 2 to 10 and G for the rest O R5 // \\ " 1 \ v C - C - OR7 stands, I. r, e R5 and Rô independently of one another denote hydrogen, Ci-C6-aikyl, phenyl or Ci-C4-aikoxy, or R5 and Rö together with the carbon atom to which they are attached form a cyclohexyl ring, R7 represents hydrogen or Ci-C4-alkyl and O? ? H3 ii ii i R8 denotes hydrogen, - C - CH = CH2 or C - C = CH2, and / or the formula III -R11O A ^ C (m), where Rio R9, R10 and R11 independently of one another are hydrogen or methyl, or are mixtures thereof. 11. The composition according to claim 10, wherein the proportion of compounds of the formula I in a mixture with compounds of the formulas II and / or III is 5 to 95% by weight, preferably 30 to 70% by weight. 12. The composition according to claim 10, wherein in the compounds of the formula I Ri denotes n-butyl, i-butyl or 2,4,4-trimethyl-pent-1-yl, R2 and R3 are identical and 2,6-dimethoxyphenyl or 2,4,6-tri-methylphenyl, and in the compounds of the formula II R5 and R6 are the same and represent methyl and R4 is hydrogen, i-propyl CHS CH, = C or a group CH3 -CH2 -C— I. G is. 13. The composition of claim 10 containing compounds of formula I in which R is n-butyl, i-butyl or 2,4,4-trimethyl-pent-1-yl, R2 and R3 are the same and 2,6-dimethoxyphenyl or 2,4,6-Trimethylphenyl mean, and a mixture of compounds of formula III, in which compounds of formula III with R9 and R10 are hydrogen and Rh is methyl to 20 wt .-% and compounds of formula III with Rg, R10 and Rh is 80% by weight of methyl. 14. Use of compounds defined in claim 1 as photoinitiators for the photopolymerization of ethylenically unsaturated compounds. 13 5 10th 15 20th 25th 30th 35 40 45 50 55 CH 682 666 A5 15. Use of a composition according to any one of claims 7-13 for the production of paints, in particular white lacquers for wood and metal coatings or clear lacquers. 16. Use of a composition according to any one of claims 7-13 for the production of printing plates. 17. Use of a composition according to any one of claims 7-13 for the production of photoresists for printed electronic circuits. 18. Use of a composition according to any one of claims 7-3 as a coating for optical fibers. 19. Use of a composition according to any one of claims 7-13 for the manufacture of three-dimensional objects by mass hardening or stereolithography. 20. Use of a composition according to any one of claims 7-13 for the production of composite materials. 14