MXPA97006542A - Compounds of molecular complex as photoinicided - Google Patents

Abstract

Compounds of molecular complexes comprising a mono-, bis- or triacylphosphine oxide compound with an alpha-hydroxyketone compound are suitable as photoinitiators for the photopolymerization of polymerizable compounds based on free radicals.

Description

COMPOUNDS OF MOLECULAR COMPLEXS AS PHOTOINICIATORS The present invention relates to molecular complex compounds comprising mono- and bisacylphosphine oxides with α-hydroxy ketones and to the use of these molecular complexes as photoinitiators. Acylphosphine oxides have been described in the literature as photoinitiators. For example, EP-A / 508 discloses the preparation and use of some moacylphosphine oxides. Other monoacylphosphine oxides and bisacylphosphine oxides are known from US Pat. No. 4,218,009. The preparation and also the use of the bisacylphosphine oxide photoinitiators is disclosed, for example, in U.S. Patent Nos. 4,737,593 and 4,792,632, as well as in GB-A 2 259 704. trisacylphosphine are disclosed, for example, in International Patent WO-A 96-7662. For example, the a-hydroxy ketone compounds are cited as photoinitiators, for example, in US Patents 4, 347, 111, and 4,672,079, as well as in EP-A 3002. The use of photoinitiator mixtures which comprise oxides of acylphosphine and α-hydroxy ketone are described, for example, in GB-A 2 259 704 or GB-A 2 292 740. There is a need for easy access photoinitiator compounds, reagents and stable during storage, which can be incorporated without problems in the formulations that are subjected to polymerization. It has now been found that molecular complex compounds comprising various photoinitiating compounds possess these properties. Therefore, the present invention provides molecular complex compounds comprising a mono-, bis- or tris-acylphosphine compound with an α-hydroxy-ketone compound. For example, compounds of molecular complexes can be prepared by generally known methods of growing crystals, for example, from dissolution or fusion methods. Such crystallization methods are known to the person skilled in the art and are also described in textbooks on chemistry, such as, for example, in the Encyclopedia Ullmann's Encyclopedia of Industrial Chemistry, Vol. A 8, 127-131, Editorial Chemie, Weinheim, New York, (1987) or in Kir-Oth er, Encyclopedia of Chemical Technology, Vol. 7, 672-81, John Wiley & Sons, New York, (1979). In the case of dissolution process, for example, the compound of the molecular complex can be prepared by dissolving the two components (ie the acylphosphine oxide compound and the α-hydroxy-ketone compound) with or without heating, in solvents or mixtures of suitable solvents to then precipitate the compounds of molecular complexes that they form, either by the addition of a solvent in which the resulting complex compound is of lower solubility or by cooling the solution in a very slow manner. Thus, for example, it is effective to cool a solution of the compounds that has been saturated at a relatively high temperature, in a container subject to uniform term conditioning, very slowly, at a lower temperature. In this case, the nucleation of the crystals can be initiated by rubbing, for example, on the wall of the container. It is also possible, for example, to continuously remove the solvent from a saturated solution of the components, for example, by evaporation, in which case the formation of the crystals of molecular complexes begins. The temperatures used in the preparation of the saturated solutions depend on the solvent or the mixture of solvents used, and they oscillate, for example, at room temperature up to 150 ° C, and in particular they will be between 50 and 100 ° C. In preparing the molecular complex compounds, the two components are preferably used in a molar ratio of 1: 1. However, it is also possible to use the components in other molar proportions, for example, between 5: 1 and 1: 5. In this case it is then possible that for the formation of the mixture it comprises a compound of molecular complex with the added component in excess. The choice of solvent when preparing molecular complexes is guided by the specific melting point of the components. In the present case the solvents particularly suitable for the different photoinitiating compounds are the aliphatic hydrocarbons, such as hexane, pentane, heptane, octane and the isomeric mixtures of these solvents. But it is also possible to use aromatic hydrocarbons, for example, xylene or toluene, etc. It is advantageous to use polar additives, for example, in amounts of 1% to 30%, for example, from 1% to 20%, especially from 1% to 5%. Examples of such additives are ethyl acetate, methyl ethyl ketone, acetone, methyl isobutyl ketone and alcohols. Equally conceivable is the use of other polar solvents, for example, linear and cyclic ethers, such as diethyl ether, tetrahydrofuran or dioxane. It is also possible to use, for example, polar solvents, such as methyl ethyl ketone, and to precipitate the resulting complex compounds with water. These solvents can be used in their pure form or can also include water, for example, as an azeotropic material. In other words, recycled solvents produced in the course of an elaboration process in an azeotropic mixture with water are equally suitable. Examples of other suitable solvents are the spirits, ie petroleum alcohols with a boiling point limit having an aromatic content of the order of 3 to 10%. These solvents can be mixed, for example, with the polar solvents described above. Other examples of suitable solvent mixtures are mixtures of isooctane and ethyl acetate but also those which include water, as already mentioned above, for example, methyl ethyl ketone and water. The crystals of resulting molecular complexes are efficiently separated from the solution by means of the usual separation measures, for example filtration. If the solvents used are high-boiling solvents, then in the course of the filtration, the precipitated molecular compound compounds are washed with a low-boiling solvent, for example, hexane in order to create the possibility of drying the crystals . The crystals are effectively dried at a slightly elevated temperature and with the application of a vacuum, in particular between 40 ° C and 50 ° C and under a pressure of around 50 mbar. It may also be appropriate to wash the crystals in order to remove the impurities. This is done, for example, by using a solvent in which the crystals are of very low solubility and which will be miscible with the mother liquor. It is also possible to prepare, for example, the compound of the complex by adding the second component directly in the course of the preparation of a component, before its isolation and thus, while it is still in solution to precipitate the complex compound by adding a solvent suitable. In the preparation, for example, of the acylphosphine oxide compound, the compound can be transferred after the oxidation step into a suitable solvent, with the addition of the α-hydroxy-ketone compound, and then the compound of the molecular complex is precipitated. It is also possible to obtain, for example, the novel compounds of molecular complexes by melting the acylphosphine oxide compounds and a-hydroxy-ketone compounds and then slowly cooling the melt. In this case it is possible, for example, to prepare the mixture of the two components first and then to melt the mixture although each component can also be individually melted and then the compounds are mixed in the molten state. The temperatures depend on the melting points of the respective components and are, for example,, between 100 ° C and 200 ° C, approximately. In some cases it is suitable to seed the melt with the crystals of the molecular complex compounds obtained from the solvent-based method. Such seeding is carried out for example, once the melt has cooled to room temperature or otherwise, also the melting point of the molecular complex compound. Fusion methods of this kind, intended to produce crystals, are known to the person skilled in the art and are described, for example, in the Ullmann Encyclopedia of Industrial Chemistry, Vol. A8, 121-127, Chemie Publishing House, Weinheim, New York, ( 1987). When the molten mass is cooled, especially when the melt is cooled rapidly, amorphous modifications can also be obtained, for example, from the novel compounds with molecular complexes. For the preparation of certain compounds of molecular complexes the rapid cooling can turn out to be little sensible since with some compounds the formation of the complex is slow. Furthermore, in the case of rapid cooling, there is a greater probability that mixtures are formed between the complex compound and one of its components. It is also conceivable that, for example, polymorphic variants of crystals of molecular complex compounds or, for example, crystals of molecular complexes containing "host molecules", for example, a solvent, according to the crystallization method are formed. . On the other hand it can be said that these mixtures are also suitable to serve as initiators for the photopolymerization. Molecular complexes are generally associated by hydrogen bonds between the H atoms of the OH group of the hydroxyketone and the oxygen atom that is attached to the P atom within the phosphine oxide compound. Preference is given to those compounds of molecular complexes in which the monobis- or tris-acylphosphine oxide compound is a compound of Formula I Q or R- -pp - ¿R (I) in which? I 3 FL R x and R 2 independently of each other represent alkyl of Ci to C 13, alkyl of C 2 to C 3 interrupted by one or several atoms of O, alkyl of Ci to C 4, substituted by phenyl, the alkenyl of C 2 to C 8, unsubstituted phenyl or substituted once up to five times by halogen, hydroxyl, Ci to C8 alkyl and / or Ci to Cs alkoxy, naphthyl instubstituted or substituted one to five times by halogen, hydroxyl, Ci to C8 alkyl and / or alkoxy of Ci to C8 biphenyl unsubstituted or substituted one to five times by halogen, hydroxyl, Ci to C8 alkyl and / or Ci to Ce alkoxy, or constitute C3 to C2 cycloalkyl, a 5- or 6-membered heterocyclic ring contains O, S or N, or a group ° í? ° or Ri is -OR4 or a group - x-P-C-R3, or - P-C-R -; ° R, R, Ri and R2 taken together are C4 to C8 alkylene and form, with the P atom to which they are attached, an annular structure; R 3 is C 1 to C 8 alkyl, C 3 to C 2 cycloalkyl, C 2 to C 8 alkenyl, phenyl, naphthyl or biphenyl each unsubstituted or substituted one to four times by Ci to C 8 alkyl, Ci alkoxy to C8, alkylthio of Ci to C8 and / or halogen, or is a 5- or 6-membered heterocyclic ring containing O, S or N or a group R 4 is Ci to Ce alkyl, phenyl, naphthyl or phenyl-alkyl of Ci to C8; Y is phenylene, Ci to C 12 alkylene, cyclopentylene or cyclohexylene; X is alkylene of Ci to C 8, alkylene of C to C, which is interrupted once or several times by -O-, -S-, O -NRS-, -P- or-SOz-, 1, or constitutes alkylene from Ci to Ce which is substituted by Cl, F, C: a C alkoxy, COOR7, phenyl, phenylC1 to C alkyl, naphthyl-alkyl of a, alkylphenyl of Ci to C4, alkylnaphthyl of Ci to C, phenylalkoxy of C to C4, naphthylalkoxy of Ci to C4, alkoxy of Ci to C4, -alkoxy Ci to C4 and / or CN, or X is C: to C8 alkylene, which is substituted by one or two radicals of the formula A X is a (A? a and b independently of each other represent 0 or 1 and the sum of dyf is a number from 3 to 8, while neither d nor f represent 0, either X is a group -CH2-CH = CH-CH2- or -CH_ -C = C-CH2-, or constitutes phenylene which is unsubstituted or substituted one to three times by Cl, F, Ci to C4 alkyl and / or C: to C4 alkoxy or represents exilylene, X is a CH group, Q is a single bond, CR9R10, -0-, -S-, -NR -.-, -S02-, (CH2) - or -CH = CH-; p is a number from 2 to 12; Z is 0 or S; R5 is hydrogen, Ci to C12 alkyl, or phenyl; R6 is Ci to C4 alkyl, or phenyl; R7 is C1 to Ci2 alkyl, C2 to C2 alkyl interrupted once or several times by -0-, or represents benzyl, phenyl, cyclopentyl or cyclohexyl; R8 is hydrogen, Ci to C4 alkyl, Ci to C4 alkoxy or halogen; R9 is hydrogen or C1 to C alkyl; and Rio is hydrogen, methyl or ethyl. Ci to Cie alkyl may be linear or branched and is for example methyl, ethyl, propyl, isopropyl, butyl, isobutyl, secondary butyl, tertiary butyl, pentyl, isopentyl, hexyl, heptyl, octyl, nonyl, decyl, dodecyl or octadecyl. The preference is given to Ci to C12, for example C: to C8 or Ci to Ce, especially Ci to C4 alkyl. The alkyls of C to C? 2, Ci to C8 and Ci to C4 can have the same meanings as indicated above up to the corresponding number of C atoms. C2 to C2 alkyl, interrupted by one or more carbon atoms. , is interrupted for example from 1 to 5 times, for example from 1 to 3 times or once or twice by -0-. Result of this are the structural units such as: -0 (CH2) 2OH, -0 (CH2) 2OCH3, 0 (CH2CH20) 2CH2CH3, -CH2-0-CH3, -CH2CH2-0-CH2CH3, - [CH2CH20] and -CH3, where y = 1 to 5, - (CH2CH20) 5CH2CH3, -CH2-CH (CH3) -0-CH2-CH2-CH3 or -CH2-CH (CH3) -0-CH2-CH3. C 1 to C 4 alkyl substituted by phenyl is for example benzyl, 2-phenylethyl, 3-phenylpropyl, α-methylbenzyl or α, α-dimethylbenzyl, especially benzyl. The phenyl alkyl of Ci to C8 is for example benzyl, phenylethyl, α-methylbenzyl, phenylpentyl, phenylhexyl, phenyloctyl or α, α-dimethylbenzyl, especially benzyl. The phenyl-C 1 to C 4 alkyl has the definitions given above to the appropriate number of C atoms. Preference is given to the phenyl-C 1 to C 4 alkyl, especially phenyl-C 1 to C 2 alkyl. The C2 to C? 8 alkenyl may be linear or branched and there may be more than one single unsaturated bond in the molecule. Examples are vinyl, allyl, methylvinyl, butenyl, butadienyl, pentenyl, hexenyl, heptenyl, octenyl, nonenyl, decenyl, dodecenyl or octadecenyl.

The alkoxy of Ci to C8 can be linear or branched chain and is for example methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, secondary butoxy, tertiary butoxy, pentoxy, isopentoxy, hexyloxy, heptyloxy or octyloxy. Preference is given, for example, to alkoxy of Ci to Cs or in particular to alkoxy of Ci to C. The alkoxy of Ci to C6 and the alkoxy of Ci to C4 may have the same definitions as indicated above to the appropriate number of C atoms. The alkoxy of Ci to C4-alkoxy of Ci to C4 is for example methoxyethoxy, methoxypropoxy , methoxybutoxy, ethoxymethoxy, ethoxyethoxy, ethoxypropoxy, ethoxybutoxy, propoxymethoxy, propoxyethoxy, propoxypropoxy, propoxybutoxy, butoxymethoxy, butoxyethoxy, butoxypropoxy or butoxybutoxy, especially methoxyethoxy and ethoxyethoxy. C 1 to C 8 alkylthio may be straight or branched chain and is, for example, methylthio, ethylthio, propylthio, isopropylthio, butylthio, tertiary butylthio, hexylthio or octylthio, especially methylthio. Halogen is, for example, chlorine, bromine and iodine, especially chlorine. The substituted phenyl is substituted between one and five times, for example once, twice or three times, especially once or twice, on the phenyl ring. The substitution occurs for example at positions 2, 3, 4, 5, 2.4, 2.5, 2.6, 3.4, 3.5, 2.4.6, or 3.4.5 of the phenyl ring. The substituents of Ci to Cd alkyl, Ci to C4 alkyl, Ci to C8 alkoxy, d to C8 alkylthio and C to C alkoxy can have the definitions indicated above. Examples of substituted phenyl are tolyl, xylyl, 4-methoxyphenyl, 2,4- and 2,5-dimethoxyphenyl, ethylphenyl and 4-alkoxy-2-methylphenyl. Examples of C 3 to C 2 cycloalkyl are cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl or cyclododecyl, preferably cyclopentyl and cyclohexyl. Ri and R2 as a 5- or 6-membered heterocyclic ring containing O-, S- or N- are, for example, furyl, thienyl, pyrrolyl, oxynyl, dioxinyl or pyridyl. If Ri and R2 taken together are alkylene from C4 to C? and with the P atom to which they are attached, to form an annular structure, then this structure can include not only simple rings but also bridged rings, for example X as Ci-Ci-alkylene is straight or branched chain alkylene, for example methylene, ethylene, propylene, isopropylene, n-butylene, sec. -butylene, isobutylene, tert.-butylene, pentylene, hexylene, heptylene, octylene, nonylene, decylene, dodecylene, tetradecylene, heptadecylene or octadecylene. In particular X is alkylene of Ci to d2, for example ethylene, decylene, and C11H23 C2H5-CH-CH2-, - CH- (CH2) 2-, - CH- (CH2) 3-, -C (CH3) 2- CH2- or -CH- -CH, - CH3 CH3 CH3 H3 An interruption of X as alkylene from Ci to Cie by O -O-, -S-, -NR5-, ll or -S02- results, for example , in i Re Structural units such as -CH2-0-CH2-, -CH2CH2- 0 -CH2CH2-, - [CH2CH20] y- where y = 1-9, - (CH2CH20) ~ CH2CH2-, -CH2- CH (CH3) -0-CH! -CH (CH3) -, -CH; -S-CH2-, -CH2CH -S-CH2CH2-, CH2CH2CH2-S-CH2CH2CH2-, - (CH2) 3-S- (CH2) 3", -CH2- (NR5) -CH2-, CH2CH2- (NR5) -CH2CH2-, -CH2- (P (O) R5) -CH2-, -CH CH2- (P (O) R6) - CH2CH2-, , -CH2-SO CH2- 0 well - (CH2) 2- -CH2CH2-SO -CH: .CH2-. Examples of C2 to C-alkylene which is substituted by one or two radicals of formula A are 0 = 0 = which R3 is as defined above. Naphthyl Ci to C4 alkyl is, for example, naphthylmethyl, naphthylethyl, naphthyl (1-methyl) et-1-yl or naphthyl (1, 1-dimethyl) et-1-yl, especially naphthylmethyl. Ci to C4 alkylphenyl is, for example, tolyl, xylyl, mesityl, ethylphenyl or diethylphenyl, preferably tolyl or mesityl. Alkylnaphthyl of Ci to C4 is naphthyl substituted by methyl, ethyl and / or propyl or butyl. Ci-C4-phenyl-alkoxy is, for example, benzyloxy, phenylethyloxy, α-methylbenzyloxy or α, -dimethylbenzyloxy, especially benzyloxy. Naphthyl-alkoxy of Ci to C4 is, for example, naphthylmethyloxy or naphthylethyloxy. Examples of groups of the formula Ai in which the sum of d and f is from 3 to 8, are:CH2- d + f = 3 d-. , -CH, -CH- Preferred groups of the formula Ai0 are - (f ^ / ^ The preparation of the acylphosphine oxide compounds of the formula I is known to those skilled in the art and is described, for example, in EP-A 7 508, in U.S. Patents 5,218,009, 4,737,593 and 4,792,632, in British Patent GB-A 2 259 704 as well as in International Patent WO-A 96/7662. Preference is given to the compounds of the formula I wherein R x and R 2, independently of each other are C 2 to C 2 alkyl, benzyl, phenyl which is unsubstituted or is substituted once to four times by halogen, especially Cl, Ci to C 8 alkyl and / or alkoxy from Ci to C8, or are cyclohexyl or C0R3, or Ri represents OR or f or -XPC-R3 R. R3 is phenyl which is unsubstituted or is substituted one to four times by alkyl of Ci to C8, especially Ci to C4 alkyl, Ci to C8 alkoxy, Ci to C, alkylthio , especially alkylthio of Ci to C4 / and / or halogen, especially chlorine or d, enota a group R4 is Ci-to Ce alkyl, especially Cx to C4 alkyl, phenyl or benzyl; X is C 1 to C 1 alkylene, especially C 6 to C 1 0 alkylene, or a group and Y is phenylene, C 2 to C 2 alkylene or cyclohexylene. Other compounds of the formula I which are of interest are those in which Ri and R 2 independently of each other represent Ci to C8 alkyl, phenyl, unsubstituted or substituted one to four times by Ci to C alkyl and / or alkoxy of Ci to C8, either constitute cyclohexyl or a C0R3 group, or O o ?? _ ?? _ Ri is a group x-P-c 3 Q well -0R4; R3 is phenyl R, unsubstituted or substituted one to four times by methyl and / or methoxy; R 4 is methyl, ethyl or phenyl; and X is alkylene from Notable compounds of formula I are those in which Ri is C0R3, R2 is Ci to C18 alkyl and R3 is phenyl which is substituted two or three times by Ci to C alkyl, or Ci to C alkoxy.

Also of particular interest are those compounds of the formula I in which Ri is C0R3, R2 is phenyl which is unsubstituted or is substituted by Cx to C alkyl and / or Ci to C alkoxy and R3 is phenyl which is substituted two or three times by alkyl of Ci to C4 or alkoxy of Ci to C. The compounds of the formula I are of particular interest when the substitution of R 3 as phenyl is located in positions 2,6 or 2,4,6. Examples of the compounds of the formula I which are useful for preparing the compounds of molecular complexes are bis (2,6-dimethoxybenzoyl) phenylphosphine oxide, bis (2,6-dimethoxybenzoyl) oxide (2,4,4-trimethylpentyl). phosphine, bis (2,6-dimethoxybenzoyl) -n-butylphosphine oxide, bis (2,6-dimethoxybenzoyl) - (2-methylprop-1-yl) phosphine oxide, bis (2,6-dimethoxybenzoyl) oxide - (1-methylprop-1-yl) phosphine, bis (2,6-dimethoxybenzoyl) -t-butylphosphine oxide, bis (2,6-dimethoxybenzoyl) cyclohexylphosphine oxide, bis (2,6-dimethoxybenzoyl) octylphosphine oxide, Bis (2-methoxybenzoyl) (2-methylprop-1-yl) phosphine oxide, Bis (2-methoxybenzoyl) (1-methylprop-1-yl) phosphine oxide, Bis (2,6-diethoxybenzoyl) oxide (2) -methylprop-1-yl) phosphine, bis (2,6-diethoxybenzoyl) (1-methylprop-1-yl) phosphine oxide, bis (2,6-dibutoxybenzoyl) (2-methylprop-1-yl) phosphine oxide , Bis (2,6-dibutoxybenzoyl) (2-methylprop-1-yl) phosphine oxide, Bis (2,, 6-trimethyl) oxide enzoyl) phenylphosphine, 2, 4, 6-trimethylbenzoyldiphenylphosphine oxide, bis (2,4,6-trimethylbenzoyl) (2,4-dipentoxyphenyl) phosphine oxide, bis (2,6-dimethoxybenzoyl) benzylphosphine oxide, bis ( 2, 6-dimethoxybenzoyl) -2-phenylpropylphosphine, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, bis (2,6-dimethoxybenzoyl) encylphosphine oxide, bis (2,6-dimethoxybenzoyl) oxide -2 -phenylpropylphosphine, bis (2,6-dimethoxybenzoyl) -2-phenylethylphosphine oxide, 2-ß-dimethoxybenzoylbenzylbutylphosphine oxide, 2-ß-dimethoxybenzoylbenzyloctylphosphine oxide, bis (2,4,6-trimethylbenzoyl) isobutylphosphine oxide and sodium oxide. 2,6-dimethoxybenzoyl-2,4,6-trimethylbenzoyl-n-butylphosphine. The a-hydroxy-ketone compounds are, in particular, the compounds of the formula II Rn and Ri: independently from each other, represent hydrogen, Ci to C alkyl, phenyl, Ci to C6 alkoxy, OSiR16 (R 2 2 or -O (CH2CH20) q-alkyl of da C6, or Rn Y R- 12-- together with the carbon atom to which they are attached form a ring of cyclohexyl, q is a number from 1 to 20, R13 is OH, alkoxy of day C? 6 or -O (CH2CH20) q-alkyl of da Ce, "R 4 is hydrogen, C 1 to C 1 alkyl, C 1 to C 8 alkoxy, - OCH 2 CH 2 -OR 5, a CH 2 = C (CH 3) - group or I is a number of 2 to B is the radical Ris is hydrogen, O O CH3 II i 3 -C-CH = CH2 or - C-C = CHa R and R17 independently of each other are Ci to d alkyl or phenyl. Examples of Ci to Cy alkyl, Ci to C6 alkyl, d to C alkyl, Ci to C y alkoxy and Ci to C6 alkoxy have been indicated above. The preparation of the a-hydroxy-ketone compounds of the formula II is familiar to the person skilled in the art and is described, for example, in U.S. Patent Nos. 4,347,111 and 4,672,079 as well as in European Patent EP-A 3002. The compounds of the formula II which are of interest, are those in which R n and R 2 independently of each other constitute hydrogen, C 1 to C 5 alkyl, or phenyl or R n and Ri - together with the carbon atom to which they are attached form a cyclohexyl ring; Ri3 is OH; and Ri 4 is hydrogen, C 1 to d 2 alkyl, d to C 2 alkoxy, especially C 1 to C 4 alkoxy, -OCH 2 CH 2 OR 5, a group CH2 = C (CH3) - or Preference is given to the compounds of the formula II wherein R n and R 2, independently of each other are methyl or ethyl or R n and R 12, together with the carbon atom to which they are attached form a cyclohexyl ring; R 3 is hydrogen and R 4 is hydrogen, alkyl of d to C 4, alkoxy of Ci to d or -OCHCH 2 OH. Examples of compounds of the formula II which are suitable for preparing the compounds of molecular complexes are a-hydroxycyclohexyl-phenyl-ketone, 2-hydroxy-2-methyl-1-phenylpropanone, 2-hydroxy-2-methyl-1- (4 -isopropylphenyl) propanone, 2-hydroxy-2-methyl-1- (4-dodecylphenyl) propanone and 2-hydroxy-2-methyl-1 - [(2-hydroxyethoxy) phenyl] propanone. Preferred molecular complex compounds are those which comprise a monoacylphosphine or bisacylphosphine oxide compound according to formula I O or II R -.Pp-.C-R3 i [I) in which R '.2 R and R2 independently from each other represent C1 to C2 alkyl, phenyl unsubstituted or substituted once or twice by alkyl of C8 and / or Ci-alkoxy well represent COR; R3 is a radical Rie is Ci to C alkyl, especially methyl, or Ci to C alkoxy, especially methoxy; and R19 is hydrogen or Ci to C alkyl, especially methyl; as well as an a-hydroxy ketone compound according to formula II R11 and i independently of each other represent alkyl of Ci to C4 or Ri and R2 together with the carbon atom to which they are attached, form a cyclohexyl ring; and Ri4 is hydrogen. In addition, preference is given to the compound of molecular complexes in which the acylphosphine oxide compound is bis (2,6-dimethoxybenzoyl) (2,, 4-trimethyl-pentyl) -phosphine oxide or 2,4-oxide, 6-tri-ethylbenzoyldiphenylphosphine and the a-hydroxy-ketone compound is a compound of the formula II in which R n and R 12 are C 1 to C alkyl or R n and R 2, together with the carbon atom to which they are attached they form a cyclohexyl ring, R 3 is OH and Ri is hydrogen. Also of interest are the molecular complex compounds in which the acylphosphine oxide compound is the bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide, bis (2, 4, 6) oxide. -trimethyl-benzoyl) (2,4-dihexyloxyphenyl) phosphine, (2,4,6-trimethylbenzoyl) (4-ethoxyphenyl) phosphine oxide or 2,4,6-trimethylbenzoyldiphenylphosphine oxide and the a-hydroxy compound. Ketone is an a-hydroxycyclohexyl-phenyl-ketone or 2-hydroxy-2-methyl-1-phenylpropane-1-one. Of particular interest are compounds of molecular complexes comprising bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide and 2-hydroxy-2-methyl-1-phenylpropanone.; Bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide and α-hydroxycyclohexyl-phenyl-ketone; Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide and α-hydroxycyclohexyl phenyl ketone; Bis (2,4,6-trimethylbenzoyl) phenylphosphine oxide and 2-hydroxy-2-methyl-1-phenylpropanone; 2, 4, 6-trimethylbenzoyldiphenylphosphine oxide and a-hydroxycyclohexyl phenyl ketone; 2, 4, 6-trimethylbenzoyldiphenylphosphine oxide and 2-hydroxy-2-methyl-1-phenylpropanone; Bis (2,4,6-trimethylbenzoyl) (4-ethoxyphenyl) phosphine oxide and a-hydroxycyclohexyl-phenyl-1-ketone; Bis (2,4,6-trimethylbenzoyl) (2,4-dipentoxyphenyl) phosphine oxide and a-hydroxycyclohexyl-phenyl-ketone; Bis (2,4,6-trimethylbenzoyl) (2,4-dihexyloxyphenyl) phosphine oxide and a-hydroxy-cyclohexyl-phenyl-ketone; Bis (2,4,6-trimethylbenzoyl) (2,4-dipentoxyphenyl) phosphine oxide and 2-hydroxy-2-methyl-1-phenylpropanone; Bis (2,4,6-trimethylbenzoyl) (2-methylpropyl) phosphine oxide and a-hydroxycyclohexyl-phenyl-ketone; Bis (2,4,6-trimethylbenzoyl) (2-methylpropyl) phosphine oxide and 2-hydroxy-2-methyl-1-phenylpropanone. Bis (2,6-dimethoxybenzoyl) (2-methylpropyl) phosphine oxide and 2-hydroxy-2-methyl-1-phenylpropanone and bis (2-6-dimethoxybenzoyl) (2-methylpropyl) phosphine oxide and a-hydroxycyclohexyl- phenyl ketone. According to the invention, the compounds of molecular complexes can be used as photoinitiators for the photopolymerization of ethylenically unsaturated compounds or of mixtures comprising such compounds. This use can also be carried out in combination with another photoinitiator and / or with other additives.

The invention, therefore, also provides photopolymerizable compositions comprising (a) At least one photopolymerizable ethylenically unsaturated compound, and (b) As a photoinitiator, at least one molecular complex compound comprising a mono-, bis-, or trisacylphosphine with an α-hydroxy ketone compound, it being possible for the composition to also comprise other photoinitiators and / or other additives in addition to component (b). The unsaturated compounds may contain one or more olefinic double bonds. They can be of a low molecular mass (monomeric) or of a relatively high molecular mass (oligomeric). Examples of monomers containing a double bond are alkyl or hydroxyalkyl acrylates or methacrylates, for example methyl, ethyl, butyl, 2-ethylhexyl or 2-hydroxyethyl acrylate, isobornyl acrylate, or else methyl or ethyl methacrylate. Silicone acrylates are also of interest. Other examples are acrylonitrile, acrylamide, methacrylamide, N-substituted (meth) acrylamides, vinyl esters such as vinyl acetate, vinyl ethers such as isobutyl vinyl ether, styrene, alkyl styrenes and haloestyrenes, N-vinylpyrrolidone, vinyl chloride or well the vinylidene chloride.

Examples of monomers containing two or more double bonds are the diacrylates of ethylene glycol, propylene glycol, neopentyl glycol, hexamethylene glycol and bisphenol A, 4,4'-bis- (2-acryloyloxyethoxy) diphenylpropane, trimethylolpropane triacrylate, pentaerythritol triacrylate or its tetraacrylate, vinyl acrylate, divinyl benzene, divinyl succinate, diallyl phthalate, triallyl phosphate, triallyl isocyanurate or tris (2-acryloylethyl) isocyanurate. Examples of polyunsaturated compounds of relatively high molecular mass (oligomeric) are acrylic epoxy resins and polyesters, polyurethanes and polyethers that are acrylic or contain vinyl ether or epoxy groups. Other examples of the unsaturated oligomers are the unsaturated polyester resins which are in most cases prepared from maleic acid, phthalic acid and one or more diols and which have molecular weights of from about 500 to 3000. In addition, there is also the possibility of using vinyl ether monomers and vinyl ether oligomers, as well as maleate-terminated oligomers having polyester, polyurethane, polyether, polyvinyl ether and epoxy backbones. Particularly useful are combinations of oligomers containing vinyl ether groups as well as corresponding polymers as described in International Report WO 90/01512. However, vinyl ether copolymers and monomers functionalized with maleic acid are also suitable. Such unsaturated oligomers can be referred to simultaneously with the term prepolymers. Examples of particularly suitable compounds are esters of ethylenically unsaturated carboxylic acids and polyols or polyepoxides as well as polymers containing ethylenically unsaturated groups in the chain or in the side groups, for example unsaturated polyesters, polyamides and polyurethanes as well as their copolymers, polybutadiene and butadiene copolymers, polyisoprene and isoprene copolymers, polymers and copolymers containing (meth) acrylic groups in the side chains, as well as mixtures of one or more such polymers. Examples of unsaturated carboxylic acids are acrylic, methacrylic, crotonic, itaconic and cinnamic acids as well as unsaturated fatty acids such as linolenic acid or oleic acid. Preference is given to acrylic and methacrylic acid. Suitable polyols are the aromatic polyols and, in particular, aliphatic and cycloaliphatic polyols. Examples of aromatic polyols are hydroquinone, 4,4'-dihydroxybiphenyl, 2,2-di (4-hydroxyphenyl) -propane, as well as novolaks and resoles. Examples of polyepoxides are those based on the aforementioned polyols, especially aromatic polyols and epichlorohydrin. Other suitable polyols include polymers and copolymers containing hydroxyl groups in the polymer chain or in the side groups, for example polyvinyl alcohol and its copolymers or poly (hydroxyalkyl methacrylates) or their copolymers. Other suitable polyols are oligoesters containing hydroxyl end groups. Examples of aliphatic and cycloaliphatic polyols are alkylene diols, which preferably have from 2 to 12 carbon atoms, such as ethylene glycol, 1,2- or 1,3-propanediol, 1,2-, 1,3- or 1. , 4-butanediol, pentanediol, hexanediol, octanediol, dodecanediol, diethylene glycol, triethylene glycol, polyethylene glycols having molecular weights preferably between 200 and 1500, 1,3-cyclopentanediol, 1,2-, 1,3- or 1,4-cyclohexanediol, 1,4-dihydroxymethylcyclohexane, glycerol, tris (β-hydroxyethyl) amine, trimethylolethane, trimethylolpropane, pentaerythritol, dipentaerythritol and sorbitol. The polyols may be partially or completely esterified with one or more unsaturated carboxylic acids; in the partial esters the free hydroxyl groups may be modified, for example they may be etherified or esterified with other carboxylic acids.

Examples of esters are: trimethylolpropane triacrylate, trimethylolethane triacrylate, trimethylolpropane trimethacrylate, trimethylolethane trimethacrylate, tetramethylene glycol dimethacrylate, triethylene glycol dimethacrylate, tetraethylene glycol diacrylate, pentaerythritol diacrylate, pentaerythritol triacrylate, pentaerythritol tetraacrylate diacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, dipentaerythritol octaacrylate tripentaerythritol, pentaerythritol dimethacrylate, pentaerythritol trimethacrylate, dimethacrylate, dipentaerythritol tetramethacrylate, dipentaerythritol octamethacrylate tripentaerythritol, pentaerythritol diitaconate, trisitaconate of dipentaerythritol, dipentaerythritol pentaitaconate, dipentaerythritol hexaitaconate, ethylene glycol diacrylate, 1,3-butanediol diacrylate, 1,3-butanediol dimethacrylate, diitaco 1,4-butanediol, sorbitol triacrylate, sorbitol tetraacrylate, pentaerythritol-modified triacrylate, sorbitol tetramethacrylate, sorbitol pentaacrylate, sorbitol hexaacrylate, oligoester acrylates and methacrylates, glycerol diacrylate and triacrylate, diacrylate 1, 4 -cyclohexane, bisacrylates and polyethylene glycol bis-methacrylates with molecular weights of 200 to 1500, or mixtures thereof. Other suitable components (a) are amides of unsaturated carboxylic acids, identical or different, with aromatic, cycloaliphatic and aliphatic polyamines preferably containing from 2 to 6 groups, and especially from 2 to 4 amino groups. Examples of such polyamines are ethylene diamine, 1,2- or 1,3-propylene diamine, 1,2-, 1,3- or 1,4-butylene diamine, 1,5-pentylenediamine, 1,6-hexylenediamine, octylenediamine, dodecylenediamine, 1, 4-diaminocyclohexane, isophorone diamine, phenylenediamine, bisphenylenediamine, di-β-aminoethyl ether, diethylenetriamine, triethylene tetramine, di (β-aminoethoxy) - or di (β-aminopropoxy) ethane. Other suitable polyamines are polymers and copolymers with or without additional amino groups in the side chain as well as polyisoamides with amino end groups. Examples of unsaturated amides are: methylenebisacrylamide, 1,6-hexamethylene bis-acrylamide, diethylenetriaminetrismethacrylamide, bis (methacrylamidopropoxy) ethane, β-methacrylamidoethyl methacrylate and N [(β-hydroxyethoxy) ethyl] acrylamide. Suitable polyesters and polyamides, unsaturated, are derived, for example, from maleic acid and diols or diamines. Some of the maleic acids can be replaced by other dicarboxylic acids. They can be used in conjunction with the ethylenically unsaturated comonomers, for example styrene. Polyesters and polyamides can also be derivatives of dicarboxylic acids and ethylenically unsaturated diols or diamines, in particular of relatively long chain compounds containing, for example, from 6 to 20 carbon atoms. Examples of polyurethanes are those structured from saturated or unsaturated diisocyanates and from unsaturated or saturated diols. Polybutadiene and polyisoprene are known as well as their copolymers. Examples of suitable comonomers are olefins such as ethylene, propene, butene, hexene, (meth) acrylate, acrylonitrile, styrene and vinyl chloride.

Polymers containing groups are also known (meth) acrylate in the side chain. They may be, for example, products of the reaction of epoxy resins based on novolac with (meth) acrylic acid, homopolymers or copolymers of vinyl alcohol or their hydroxyalkyl derivatives which have been esterified with the use of acid (meth) acrylic, or homopolymers and copolymers of (meth) acrylates which have been esterified with the use of hydroxyalkyl- (meth) acrylates. The photopolymerizable compounds can be used alone or in any desired mixtures. Preference is given to mixtures of polyol (meth) acrylates. It is also possible to add binders to the compositions according to the invention; this is particularly sensible when the photopolymerizable compounds are liquid or viscous substances. The binder amount can be, for example, from 5 to 95% by weight and preferably it will be between 10 and 90% by weight and very particular between 40 and 90% by weight, based on the general solid content. The binder is chosen according to the field of its application and according to the properties required for it, such as the ease to develop in certain systems of aqueous and organic solvents, its adhesion to substrates and its sensitivity to oxygen. Examples of suitable binders are polymers having a molecular weight of about 5000 to 2,000,000 and preferably 10,000 to 1,000,000. Examples are acrylates and methacrylates of the homopolymer and copolymer type, such as methyl methacrylate copolymers. ethyl acrylate / methacrylic acid, poly (alkyl methacrylates), poly (alkyl acrylates); cellulose esters and cellulose ethers, such as cellulose acetate, cellulose acetate butyrate, methyl cellulose and ethyl cellulose; polyvinyl butyral, polyvinyl formal, cyclized rubber, polyethers, such as polyethylene oxide, polypropylene oxide and polytetrahydrofuran; polystyrene, polycarbonate, polyurethane, chlorinated polyolefins, polyvinyl chloride, copolymers of vinyl chloride / vinylidene chloride, copolymers of vinylidene chloride with acrylonitrile, methyl methacrylate and vinyl acetate, polyvinyl acetate, copolymer (ethylene / vinyl acetate) , polymers such as polycaprolactam and poly (hexamethylene adipamide), and polyesters such as poly (ethylene glycol terephthalate) and poly (hexamethylene glycol succinate). The unsaturated compounds can also be used in mixtures with non-photopolymerizable film-forming components. They can be, for example, physically drying polymers or their solutions in organic solvents, for example nitrocellulose and cellulose acetobutyrate. However, they can also be chemically curable or heat curable resins for example polyisocyanates, polyepoxides and melamine resins. The additional use of heat-curable resins is important for use in so-called hybrid systems that are light-cured in a first stage and interlaced by subsequent thermal treatment in a second stage. The photoinitiators according to the invention are also suitable as initiators for the curing of oxidative drying systems, as described for example in Lehrbuch der Lacke und Beschichtungen [textbook of paints and coatings] Volume III, 296-328, Verlag W.A. Colomb in der Heenemann GmbH, Berlin-Oberschwandorf (1976). The photopolymerizable mixtures may contain various additives in addition to the photoinitiator. Examples thereof are thermal inhibitors, which serve to prevent premature polymerization, for example hydroquinone, hydroquinone derivatives, p-methoxyphenol, β-naphthene and stereo-hindered phenols such as 2,6-di (tert-butyl) -p- cresol Shelf life in the dark can be increased for example by using copper compounds such as copper naphthenate, copper stearate or copper octoate, phosphorous compounds, for example, triphenylphosphine, tributylphosphine, triethylphosphite, triephenylphosphite or tribenzylphosphite, the compounds of quaternary ammonium, such as for example tetramethylammonium chloride or trimethylbenzylammonium chloride, or hydroxylamine derivatives, for example N-diethylhydroxylamine. In order to exclude atmospheric oxygen during the polymerization, paraffin or similar substances similar to wax may be added; they migrate to the surface at the beginning of the polymerization due to their low solubility in the polymer to form a transparent surface layer that prevents the entry of air. Similarly, a layer impermeable to oxygen can be applied. The photostabilizers that can be added are the absorbers of ultraviolet light, for example those of the hydroxyphenylbenzotriazole, hydroxyphenylbenzophenone, oxalamide or hydroxyphenyl-s-triazine type. These compounds can be used individually or as mixtures with or without the use of stereo-hindered amines ("HALS"). Examples of such ultraviolet ray absorbers and photostabilizers are 1. 2- [2'-Hydroxyphenyl) benzotriazoles, for example 2- (2'-hydroxy-5'-methylphenyl) -benzotriazole, 2- (3 ', 5'-di) -ter -butyl-2'-hydroxyphenyl) benzotriazole, 2- (5'-tert.-buty1-2'-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-5 '- (1,1,3,3 - tetramethylbutyl) phenyl) -benzotriazole, 2- (3 ', 5'-di-tert-butyl-2'-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3'-tert-butyl-2'-hydroxy) 5'-methylphenyl) -5-chlorobenzotriazole, 2- (3'-sec-butyl-5'-ether. -butyl-2'-hydroxyphenyl) benzotriazole, 2- (2'-hydroxy-4'-octoxyphenyl) benzotriazole, 2- (3 ', 5' -di-tert.-ami1-2'-hydroxyphenyl) benzotriazole, 2- (3 ', 5'-bis (a, a-dimethyl-benzyl) -2'-hydroxyphenyl) -benzotriazole , a mixture of 2- (3 '-ter., butyl-2'-hydroxy-5' - (2-octyloxycarbonylethyl) phenyl) -5-chlorobenzotriazole, 2- (3'-ter. -buti1-5 '[2 - (2-ethylhexyloxy) carbonylethyl] -2'-hydroxyphenyl) -5-chlorobenzotriazole, 2- (3'-tert.-butyl-2'-hydroxy-5 '- (2metox icarbonylethyl) phenyl) -5-chlorobenzotriazole, 2- (3 'tert -butyl-2'-hydroxy-5' - (2-methoxycarbonylethyl) phenyl) -benzotriazole, 2- (3'-tert-butyl-2 ' hydroxy-5 '(2-octyloxycarbonylethyl) phenyl) benzotriazole, 2- (3'-tert-butyl-5' - [2- (2-ethylhexyloxy) carbonylethyl] -2'-hydroxyphenyl) benzotriazole, 2- (3 '- dodecyl-2'-hydroxy-5'-methylphenyl) benzotriazole, and 2- (3'-tert.-butyl-2'-hydroxy-5 '- (2-isooctyloxycarbonylethyl) phenylbenzotriazole, 2,2'-methylenebis [4- ( 1, 1, 3, 3-tetramethylbutyl-6-benzotriazol-2-ylphenyl]; the product of the transesterification of 2- [3'-tert-butyl-5 '- (2-methoxy-carbonylethyl) -2'-hydroxyphenyl] benzotriazole with polyethylene glycol 300; [R-CH2CH2-COO (CH2) 3) 2 where R = 3 '-ter. -butyl-4 '-hydroxy-5' -2H-benzotriazol-2-ylphenyl. 2. 2-hydroxybenzophenones, for example the 4-hydroxy, 4-methoxy, 4-octoxy, 4-decyloxy, 4-dodecyloxy, 4-benzyloxy, 4, 2 ', 4' -trihydroxy and 2'-hydroxy derivative 4, 4'-dimethoxy. 3. The esters of substituted or unsubstituted benzoic acids, for example 4-tert.-butyl-phenyl salicylate, phenyl salicylate, octylphenyl salicylate, dibenzoylresorcinol, bis (4-tert.-butylbenzoyl) resorcinol, benzoylresorcinol, 2,4-di. -tert.-butylphenyl 3, 5-di-ter. - butyl-4-hydroxybenzoate, hexadecyl-3, 5-di-tert.-butyl-4-hydrozibenzoate, octadecyl-3, 5-di-tert.-butyl-4-hydroxybenzoate, 2-methyl-4,6-di-ter . -butylphenyl 3, 5-diTER. -buti1-4-hydroxybenzoate. 4. Acrylates, for example ethyl a-cyano-β, β-diphenylacrylate or isooctyl a-cyano-β, β-diphenylacrylate, methyl a-carbomethoxycinnamate, methyl a-cyano-β-methyl-p-methoxycinnamate or butyl a -cyano-ß-methyl-p-methoxycinnamate, methyl a-carbomethoxy-p-methoxycinnamate and N- (β-carbomethoxy-β-cyanovinyl) 2-methylindoline. Steamed amine amines, for example bis- (2, 2, 6, 6-tetramethylpiperidyl) sebacate, bis (2, 2,6,6-tetramethylpiperidyl) succinate, bis (1,2,2,6,6-petamethylpiperidyl) sebacate , bis (1,2,2,6,6-pentamethylpiperidyl) n-butyl 3,5-di-tert.-butyl-4-hydroxybenzylmalonate; the condensate of 1-hydroxyethyl-2,2,6,6-tetramethyl- 4-hydroxypiperidine and succinic acid, the condensate of N, N'-bis (2, 2, 6, 6-tetramethyl-4-piperidyl) hexamethylenediamine and 4-tert.-octylamino-2,6-dichloro-1,3, 5-s-triazine, tris (2, 2, 6, 6-tetramethyl-4-piperidyl) nitrotriacetate, tetrakis (2, 2, 6, 6-tetramethyl-4-piperidyl) 1,, 2, 3, 4-butanetetraoate , 1,1'- (1,2-ethanediyl) bis- (3,3,5,5,5-tetramethylpiperazinone), 4-benzoyl-2, 2,6,6,6-tetramethylpiperidine, 4-stearyloxy 2, 2, 6, 6-tetramethylpiperidine, bis (1, 2, 2, 6, 6-pentamethylpiperidyl-2-n-butyl-2- (2-hydroxy-3,5-di-tert.-butyl-benzyl) malonate. octyl-7, 7, 9, 9-tetramethyl-1,3, 8-triazaspiro [4.5] decane-2,4-dione, bis (1-octyloxy-2, 2, 6, 6-tetra methylpiperidyl) sebacate, bis (1-octyloxy-2,2,6,6-tetramethylpiperidyl) succinate, the condensate of N, N'-bis (2,2,6,6-tetramethyl-4-piperidyl) hexamethylenediamine and 4- morpholino-2,6-dichloro-1,3,5-triazine, the condensate of 2-chloro-4,6-di (4-n-butylamino-2, 2,6,6-tetramethylpiperidyl) -1,3, 6-triazine and 1,2-bis (3-aminopropylamino) ethane), the condensate of 2-chloro-4,6-di (4-n-butylamino-l, 2,2,6,6-pentamethylpiperidyl) -1 , 3, 5-triazine and 1,2-bis (3-aminopropylamino) ethane, 8-acetyl-3-dodecyl-7, 7, 9, 9-tetramethyl-1,3,8-triazaspiro [.5] decane- 2,4-dione, 3-dodecyl-1- (2, 2, 6, 6-tetramethyl-4-piperidyl) pyrrolidine-2,5-dione, 3-dodecyl-1- (1,2,2,6, 6-pentamethyl-4-piperidyl) pyrrolidine-2,5-dione. Oxalamides, for example 4,4'-dioctyloxyoxanilide, 2,2'-diethoxyoxanilide, 2,2'-dioctyloxy-5, 5'-di-ter. -butyloxanilide, 2, 2'-didodecyloxy-5, 5'-di-ter. butyloxanilide, 2-ethoxy-2'-ethyloxanilide, N, N'-bis (3-dimethylaminopropyl) oxalamide, 2-ethoxy-5-ter. -butyl-2'-ethyloxanilide and its mixture with 2-ethoxy-2'-ethyl-5,4'-di-tert-butyloxanilide and the mixtures of the oxanilides disubstituted by o- and p-methoxy and o- and p-ethoxy. 2- (2-hydroxyphenyl) -1,3,5-triazines, for example, 2,4,6-tris (2-hydroxy-4-octyloxyphenyl) -1,3,5-triazine, 2- (2-hydroxy) 4-octyloxyphenyl) -4,6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- (2,4-dihydroxyphenyl) -4,6-bis (dimethylphenyl) -1,3, 5-triazine, 2,4-bis (2-hydroxy-4-propyloxyphenyl) -6- (2, -dimethylphenyl) -1,3,5-triazine, 2- (2-hydroxy-4-dodecyloxyphenyl) -4, 6-bis (2,4-dimethylphenyl) -1,3,5-triazine, 2- [2-hydroxy-4- (2-hydroxy-3-butyloxypropyloxy) phenyl] -4,6-bis (2, 4- dimethylphenyl) -1,3,5-triazine and 2- [4-dodecyltridecyloxy (2-hydroxypropyl) oxy-2-hydroxy-phenyl] -4,6-bis (2,4-dimethylphenyl) -1, 3, 5- triazine. 8. Phosphites and phosphonites, for example triphenyl phosphite, diphenyl alkyl phosphites, phenyl dialkyl phosphites, tris (nonylphenyl) phosphite, triauryl phosphite, trioctadecyl phosphite, distearyl pentaerythritol diphosphite, tris (2,4-di-tert.-butylphenyl) phosphite, diisodecyl pentaerythritol diphosphite, bis (2,4-di-tert.-butylphenyl) pentaerythritol diphosphite, bis (2,6-di-tert.-butyl-4-methylphenyl) pentaerythritol diphosphite, bisisodecyloxypentaerythritol diphosphite, bis (2,4-di-tert.-butyl) -6-methylphenyl) pentaerythritol diphosphite, bis (2,4,6-tri-tert.-butylphenyl) pentaerythritol diphosphite, tristearyl sorbitol triphosphite, tetrakis (2,4-di-tert.-butylphenyl) -4,4'-biphenylene diphosphonite , 6-isooctyloxy- 2,4,8,10-tetra-tert-butyl-12H-dibenzo [d, g] -l, 3,2-dioxaphosphocin, 6-fluoro-2, 4, 8, 10-tetra -ter. -butyl-12-methyl-dibenzo- [d, g] -1, 3, 2-dioxaphosphocin, bis (2,4-di-tert.-butyl-6-methylphenyl) methyl phosphite, bis (2, 4-di) -ter .- butyl-6-methylphenyl) ethyl phosphite. The invention therefore also provides a photopolymerizable composition comprising as photoinitiator at least one molecular complex compound comprising a mono-, bis- or tris-acylphosphine oxide compound with an α-hydroxy ketone compound, and also an absorber ultraviolet of the class of hydroxyphenyl-s-triazines and / or hydroxy-phenylbenzotriazoles and / or stereo-hindered amines based on 2,2,6,6-tetramethylpiperidines. To accelerate the photopolymerization it is possible to add amines, for example triethanolamine, N-methyldiethanolamine, ethyl p-dimethylaminobenzoate or Michler's ketone. The action of the amines can be enhanced by the addition of aromatic ketones of the benzophenone type. Examples of amines that can be used as oxygen scavengers are the substituted N, N-dialkylanilines as described in European Patent EP-A-339-841. Other accelerators, coinitiators and auto-oxidants are thiols, thioethers, disulfides and phosphines as described, for example, in EP-A-438 123 and in GB-A-2 180 358. Light-curing can be accelerated also by the addition of photosensitizers that displace or expand the spectral sensitivity. They are, in particular, the aromatic carbonyl compounds, such as the benzophenone derivatives, thioxanthone derivatives, anthraquinone derivatives and the 3-acylcoumarin derivatives and the 3- (aroylmethylene) thiazolines, as well as the eosin dyes, rhodamine and erythrosine. The curing process may be adjuvanted, in particular, by compositions which are pigmented (for example with Ti02), but also by the addition of a component that forms free radicals under thermal conditions, such as for example an azo compound such as 2, 2'-azobis (4-methoxy-2,4-dimethylvaleronitrile, a triazine, the diazo sulfide, pentazadiene or a peroxy compound such as a hydroperoxide or the peroxycarbonate, for example t-butyl hydroperoxide, as described for example in EP-A-245 630. The compositions according to the invention may also contain some dye of the photo-reducible type, for example the dyes of xanthene, benzoxanthene, benzothioxanthene, thiazine, pyronine, porphyrin or acrinin, and / or a trihalomethyl compound which can be disintegrated by radiation.Similar compositions are described for example in European Patent EP-A-445 624. Other conventional additives, according to the application Optical brighteners, fillers, pigments, dyes, wetting agents or leveling adjuvants are contemplated. Thick, pigmented coatings can be effectively cured through the addition of glass microgranules or powdered glass fibers, as described for example in US-A-5 013 768. The invention also relates to compositions that comprise as component (a) at least one photopolymerizable ethylenically unsaturated compound, which has been emulsified or dissolved in water. Dispersions of aqueous prepolymers curable by radiation, of this type, are in the market in many variants. This term has been taken to refer to a dispersion of water and at least one prepolymer dispersed therein. The concentration of water in these systems is, for example, from 5 to 80% by weight, in particular from 30 to 60% by weight. The prepolymer or the mixture of prepolymers, curable by means of radiation, is present, for example, in concentrations of from 95 to 20% by weight, in particular from 70 to 40% by weight. The total of the percentages indicated for water and prepolymer in these compositions is in each case 100, to which auxiliaries and additives in different amounts are added, according to the application. The film-forming prepolymers, dispersed in water, curable by radiation, which are often also dissolved, are, for the dispersions of aqueous prepolymers, the monofunctional or polyfunctional ethylenically unsaturated prepolymers, which are known per se, and which can be initiated by means of free radicals. They contain, for example, from 0.01 mol to 1.0 mol of polymerizable double bonds per 100 g of prepolymer, and have an average molecular weight of, for example, at least 400, and in particular from 500 to 10,000. However, according to the contemplated application, prepolymers having higher molecular weights may also be suitable. For example, polyesters containing polymerizable CC double bonds and having a maximum acid number of 10, polyethers containing polymerizable CC double bonds, hydroxyl-containing products of the reaction of a polyepoxide containing at least two epoxide groups per molecule with at least one α, β-ethylenically unsaturated carboxylic acid, the polyurethane- (meth) acrylates and α, β-ethylenically unsaturated acrylic copolymers containing acrylic radicals are used in this case, as described in the specification EP-A-12 339. Mixtures of these prepolymers can also be used. Equally suitable are the polymerizable prepolymers which are described in EP-A-33 896, which are thioether adducts for polymerizable prepolymers having an average molecular weight of at least 600, a content of carboxyl groups from 0.2 to 15% and a content of 0.01 mol to 0.8 mol of polymerizable double CC bonds per 100 g of prepolymer. Other suitable aqueous dispersions, based on certain specific alkyl (meth) acrylate polymers, are described in European Specification EP-A-41 125, and water-dispersible, radiation-curable prepolymers, useful in this case, prepared from of urethane acrylates as disclosed in German specification DE-A-2 936 039. These dispersions of prepolymers, aqueous and radiation curable, may contain as other additives, dispersion aids, emulsifiers, antioxidants, photo-stabilizers , dyes, pigments, fillers, for example talc, gypsum, silica, rityl, carbon black, zinc oxide and iron oxides, reaction accelerators, leveling agents, lubricants, humectants, thickeners, opacifiers, antifoams and other auxiliaries that are conventional in surface coating technology. Suitable adjuvants for the dispersion are water-soluble, high molecular weight organic compounds containing polar groups, for example polyvinyl alcohols, polyvinyl pyrrolidone and cellulose ethers. The emulsifiers which can be used here are nonionic emulsifiers and, where appropriate, also ionic emulsifiers. The photopolymerizable compositions contain the photoinitiator (b) effectively in an amount from 0.05 to 15% by weight, and preferably from 0.1 to 5% by weight, based on the composition. In certain cases it may be advantageous to use, in addition to the molecular complex photoinitiator compound, according to the present invention, other known photoinitiators, for example benzophenone, benzophenone derivatives, acetophenone, acetophenone derivatives, for example a-hydroxycycloalkyl-phenyl-ketone, dialkoxyacetophenone, a-hydroxy- or a-aminoacetophenone, 4-aroyl-l, 3-dioxolane, benzoin alkyl ethers and benzyl ketals, mono-acylphosphine oxides, bisacylphosphine oxides, ferrocenes or titanocenes. When the photoinitiators of molecular complexes according to the invention are used in hybrid systems, cationic photoinitiators such as benzoyl peroxide, aromatic sulfonium, phosphonium or iodonium salts or also salts of cyclopentadienylarenerone (II) complexes are used in addition to the curative agents of the invention. free radicals according to the invention. The photopolymerizable compositions can be used for different purposes, for example, as printing dyes, as clear coatings or coatings, as white paints, for example for wood or metals, as coating compositions, for example for paper, wood, metal or plastic, as curable coatings under daylight for buildings and road marking, for photographic reprocessing processes, for holographic recording materials, for image recording processes or for the production of printing plates that can be developed with the use of organic solvents or aqueous alkaline media , for the production of masks for screen printing, as dental filling materials, as adhesives, as pressure sensitive adhesives, laminating resins, materials resistant to cauterization or permanent resistances and as welding masks for electronic circuits, for production from to three-dimensional items by bulk curing (ultraviolet cure in transparent molds) or by the stereolithography process as described for example in US Pat. No. 4 575 330, for the preparation of composite materials (for example styrenic polyesters, which may contain glass fibers and other adjuvants) as well as other thick-film compositions, for coating or encapsulation of electronic components or as coatings for optical fibers. The compounds of molecular complexes according to the invention can also be used as initiators for emulsion polymerizations, as initiators of a polymerization for the fixation of ordered states of monomers and oligomers of the liquid / crystalline type and as initiators for fixing dyes for organic materials In surface coatings, mixtures of a prepolymer with polyunsaturated monomers that also contain a monounsaturated monomer are often used. Here the prepolymer is basically responsible for the properties of the coating film, and its variation allows the person skilled in the art to influence the properties of the cured film. The polyunsaturated monomer functions as an interlacing agent in which it makes the coating film insoluble. The monounsaturated monomer functions as a reactive diluent by means of which the viscosity is reduced without the need to use a solvent. Unsaturated polyester resins are used in most cases in bi-component systems in combination with a monounsaturated monomer, preferably styrene. For photoresistors, certain specific monocomponent systems are often used, for example the use of polymaleimides, polyhalcondes or polyimides, as described in German Specification DE-A 2 308 830. The compounds of molecular complexes according to the invention can also be used as photoinitiators of free radicals or photoinitiating systems for coatings with radiation curable powders. These coatings in powder form can be based on solid resins or on monomers containing reactive double bonds, for example maleates, vinyl ethers, acrylates, acrylamides and their mixtures. A free-radical ultraviolet radiation curable powder coating can be formulated by mixing unsaturated polyester resins with solid acrylamides (for example methyl methacrylamidoglycolate) and with a free radical photoinitiator according to the invention, as described by example in the article "Radiation Curing of Powder Coating", Conference Proceedings, Radtech Europe 1993 by M. Wittig and Th. Gohmann. Similarly, free radical ultraviolet-curable powder coatings can be formulated by mixing unsaturated polyester resins with solid acrylates, methacrylates or vinyl ethers as well as with a photoinitiator according to the invention. The powder coatings may also comprise binders as described for example in German specification DE-A-42 28 514 and European report EP-A-636-669. The UV curable powder coatings may also comprise white or colored pigments. Thus, for example, rutile titanium dioxide can be used in concentrations of up to 50% by weight to produce a cured powder coating which will have a good coating capacity. The process normally comprises the electrostatic or tribostatic spraying of the powder onto the substrate, for example metal or wood, the melting of the powder by heating and once a smooth film is formed, radiation curing of the coating is carried out using ultraviolet and / or visible light. , for example with medium pressure mercury lamps, metal halide lamps or xenon lamps. A particular advantage of radiation-curable powder coatings compared to hot-curable counterparts is that the flow time after melting of the powder particles can be selectively extended to ensure the formation of a smooth, high-gloss coating . In contrast to hot-curable systems, radiation-curable powder coatings can be formulated without suffering the undesirable effect of a reduction in their active life so that they melt at relatively low temperatures. For this reason they are also suitable as coatings for heat sensitive substrates such as wood or plastics. In addition to the photoinitiators of molecular complexes according to the present invention, the formulations of the powder coatings may also include ultraviolet light absorbers. Suitable examples have been listed above under sections 1.-8. The photocurable compositions according to the invention are suitable, for example, as coating substances for substrates of all kinds, for example wood, textiles, paper, ceramics, glass, plastics, polyesters, polyethylene terephthalate, polyolefins or cellulose acetate, especially in the form of films and also for metals such as Al, Cu, Ni, Fe, Zn, Mg or Co and GaAs, Si or Si02, on which it is desired to apply a protective coating or some image, by exposure based on images. The substrates can be coated by applying a liquid composition, a solution or suspension to the substrate. The choice of solvent and the concentration depend mainly on the type of composition and the coating process. The solvent must be inert: in other words, it must not undergo any chemical reaction with the components and must be able to be removed again once the coating operation has been carried out, during the drying process. Examples of suitable solvents are ketones, ethers and esters, such as methyl ethyl ketone, isobutyl methyl ketone, cyclopentanone, cyclohexanone, N-methylpyrrolidone, dioxane, tetrahydrofuran, 2-methoxyethanol, 2-ethoxyethanol, 1-methoxy-2-propanol, 1, 2-dimethoxyethane, ethyl acetate, n-butyl acetate and ethyl 3-ethoxypropionate. With the use of known coating processes, the solution is applied uniformly to a substrate, for example by rotating coating, dip coating, knife coating, curtain coating, brushing, spraying, especially electrostatic spraying, and reverse doctor coating. It is also possible to apply the photosensitive layer to a temporary flexible support and then to coat the final substrate, such as a copper-laminated circuit board, by means of a layer transfer through lamination. The amount applied (thickness of the layer) and the nature of the substrate (layer support) are functions of the desired application. The range of coating thicknesses generally comprises values from about 0.1 micron to more than 10 microns. The radiation sensitive compositions according to the present invention find their application as negatively resistant materials possessing a very high photosensitivity and can be developed in an aqueous-alkaline medium without swelling. They are suitable as photoresistors for electronics (electroplating resistors, cauterization resistors and welding resistors), the production of printing plates as offset printing plates or silk-screen printing forms, and can be used for chemical treatment or as micro-resistors in the production of integrated circuits. There is a correspondingly wide range of variants in the possible supports of the layer and in the processing conditions for the coated substrates. Examples of the layer supports for recording photographic information are films made of polyester, cellulose acetate or paper coated with plastic; for printing plates of the offset type, especially treated aluminum; for the production of printed circuits, laminates with copper surfaces, and for the production of integrated circuits, as well as silicone wafers. The thicknesses of the layer for photographic materials and offset printing plates are generally between 0.5 microns to 10 microns, while for printed circuits they are 0.4 to 2 microns, approximately. After the coating of the substrates, the solvent is generally removed by drying to leave behind a layer of the photoresist material on the substrate. The term "image-based exposure" refers to both exposure through a photographic mask that contains some predetermined pattern or design, such as a transparency, such as exposure through a laser beam, which moves under control from a computer, for example, above the coated substrate, to generate an image, as well as radiation with electron rays controlled by computer.

After the image exposure of the material and before the development it can be advantageous to carry out a brief heat treatment in which only the exposed parts are thermally cured. The temperatures employed are generally 50 to 150 ° C and preferably 80 to 130 ° C; The duration of the heat treatment is generally between 0.25 and 10 minutes. The photocurable composition can also be used in a process for producing printing plates or photoresist materials, as described for example in German specification DE-A-40 13 358. In this process the composition is exposed before, simultaneously with or after of the irradiation by images, the exposure being carried out for a short period with visible light having a wavelength of at least 400 nm without a mask. After exposure and optional heat treatment, the unexposed areas of the photoresist material are removed using a developer in a manner known per se. As already mentioned, the compositions according to the invention can be developed by applying an aqueous-alkaline medium. Suitable aqueous-alkaline developer solutions are in particular aqueous solutions of tetraalkylammonium hydroxide or alkali metal silicates, phosphates, hydroxides and carbonates of this type. Relatively small amounts of wetting agents and / or organic solvents can also be added, if desired, to these solutions. Examples of typical organic solvents, which can be added in small amounts to the disclosure liquids are cyclohexanone, 2-ethoxyethanol, toluene, acetone and mixtures of such solvents. Photo curing is of considerable importance for the printing inks, since the time of drying of the binder is a crucial factor for the production rate of graphic products and this time must be in the order of fractions of seconds. Ultraviolet curable inks are important, particularly for screen printing. As already mentioned, the mixtures according to the invention are also highly useful for the production of printing plates in which for example mixtures of linear soluble polyamides or styrene / butadiene or butadiene and isoprene rubber, polyacrylates or polymethyl- methacrylates containing carboxyl groups, polyvinyl alcohols or urethane acrylates with polymerizable monomers, for example acrylamides, methacrylamides, acrylates or methacrylates, as well as a photoinitiator. Films and plates made from these systems (wet or dry) are exposed through the negative (or positive) of the original impression, and the uncured parts are then removed by washing with the use of a suitable solvent. Another field of application for photocuring lies in metal coatings, for example in the coating of metal sheets and tubes, cans or caps for bottles and the photocuring of plastic coatings, for example coatings for walls or floors, based on PVC As examples of the photocuring of paper coatings are mentioned the colorless coating of labels, covers for discs or covers for books. The use of the compounds according to the invention for curing shaped shaped articles of the composite compositions is likewise of interest. The composite composition is made from a self-supporting matrix material, for example a fiberglass fabric or also, for example, vegetable fibers [cf. K.-P. Mieck and T. Reusmann in Kunstostoffe 85 (1995), 366-370], which is impregnated with the photocurer formulation. The shaped articles that are produced from the composite compositions with the use of the compounds according to the invention are of high mechanical stability and strength. The compounds according to the invention can also be used as light-curing agents in molding compositions, impregnation and coating, as described, for example, in EP-A-7086. Examples of such compositions are fine coating resins on which certain stringent requirements apply with respect to their curative activity and resistance to yellow staining or to fiber-reinforced moldings such as for example light diffusion panels, longitudinal or transversely corrugated. Processes for the production of such moldings, for example hand placement processes, spraying, centrifugal winding or filaments, are described, for example, in P.H. Selden in "Glasfaserverstárkte kunststoffe" [Fiberglass reinforced plastics], page 610, Editorial Springer, Berlin-Heidelberg-New York, 1967. Examples of items that can be produced by this process are boats, chipboard panels or wood plywood, coated on both sides with plastic reinforced with fiberglass, pipes, containers and the like. Other examples of molding, impregnation and coating compositions are the UP resin fine coatings for glass fiber containing moldings (GRP), for example corrugated sheets and paper laminates. Paper laminates can also be based on urea or melamine resins. The thin coating is produced on a support (for example a sheet) before producing the laminate. The photocurable compositions according to the invention can also be used for casting resins or for encapsulating articles such as electronic components and the like. In curing mercury lamps of medium pressure are used as is conventional in curing with ultraviolet light. However, less intense lamps are also of particular interest, for example those of the TL40W / 03 or TL40W / 05 type. The intensity of these lamps corresponds approximately to that of sunlight. It is also possible to use direct sunlight for healing. Another advantage is that the composite composition can be removed in a partially cured plastic state from the light source and then subjected to configuration. The complete cure is carried out subsequently. Equally important is the use of photocurable compositions for image-creating processes and for the optical production of information carriers. In these applications, the coating (wet or dry) applied to the support is irradiated - as already described above - with ultraviolet light or visible light through a photographic mask and the unexposed areas of the coating are removed by treatment with a solvent (= developer) The photocurable layer can also be applied by electrodeposition in metal. The exposed areas are interlaced / polymeric and therefore insoluble and remain above the support. If proper coloration is carried out, visible images are formed. If the support is a metallized layer, then the metal can be removed from the unexposed areas, through a cauterization after exposure and development or it can also be increased in thickness by electroplating. In this way, electronic printing circuits and photoresist materials can be produced. The photosensitivity of the compositions according to the invention generally varies from the ultraviolet region (around 200 nm) up to about 600 nm. Suitable radiation comprises, for example, sunlight or light from artificial sources. Therefore, a large number of very different types of light sources can be used. Both the sources of light points and flat radiators (lamp mats) are adequate resources. Examples are carbon arc lamps, xenon arc lamps, mercury lamps of medium pressure, high pressure and low pressure, doped with metal halides if desired (metallic halogen lamps), metal vapor lamps stimulated with microwaves, excimer-type lamps, superactinic fluorescent tubes, fluorescent lamps, incandescent argon lamps, electronic lanterns, photo-flow lamps, electronic rays and X-rays. The distance between the lamp and the substrate according to the invention that must be to be coated may vary according to the application and according to the type and / or the power of the lamp, and will be, for example, between 12 cm and 150 cm. Equally suitable are, for example, lasers in the visible range. Therefore, the invention also provides a method for the photopolymerization of compounds having ethylenically unsaturated double bonds, comprising the irradiation of a composition according to the invention as described above, with light in the range of 200 to 600 nm. The invention also provides the use of the composition described above for the production of surface coating materials, printing inks, printing plates, dental compositions and strength materials, as well as recording or image recording material, especially for holographic records. The invention similarly provides a coated substrate that is coated on at least one surface with a composition as described above, as well as refers to a process for the photographic production of enhanced images, in which a substrate is subjected to. coated to an image exposure and then remove the unexposed portions with a solvent. This exposure can take place either through a mask or by means of a laser beam without a mask.

The compounds of molecular complexes according to the invention can be easily incorporated into the formulations that must be cured. The compounds of molecular complexes according to the invention generally contain less impurities than the individual components, since in the course of the preparation, the impurities remain in solution. Therefore, these photoinitiators are also suitable for very sensitive applications. The molecular complex compounds according to the invention are of good stability during storage. In preparing the compounds of molecular complexes it is likewise formed that mixtures between the crystals of molecular complexes according to the invention and a copy of the components used for their preparation, for example, a mixture of crystals of molecular complexes consisting of compounds of the formulas I and II, and crystals of the compounds of the formula I. These mixtures can also be used as photoinitiators. The following examples illustrate the invention in greater detail. As in the rest of the description and in the claims, the parts or percentages are by weight unless otherwise indicated. Example 1: Molecular complex of bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine and a-hydroxycyclohexylphenyl ketone oxide. To prepare the seed crystals, the bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and α-hydroxycyclohexylphenyl ketone oxide are dissolved in a molar proportion of 1: 1 at 80 ° C in a mixture of isooctane and ethyl acetate (weight ratio 2.3: 1). Nucleation is initiated at 53 to 55 ° C by rubbing on the glass wall using a glass rod until the crystallization process begins. The crystals obtained in this way are used as seed crystals in the first preparation of larger amounts of the molecular complex. Preparation of larger amounts of the molecular complex crystals: 385 g of bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and 165 g of a-hydroxycyclohexyl-phenyl ketone are dissolved in a mixture of 385 g of Isooctane and 165 g of ethyl acetate at 80 ° C. The mixture is cooled to 53 to 55 ° C. The present emulsion is seeded at this temperature with the corresponding mixed crystal modification and crystallized. After filtering at 20 ° C the product is washed with the solvent mixture and dried at about 70 ° C and 50 millibars to generate 530 g of dry crystalline product, ie the equivalent of 96% of the theory. The melting point (determined by a Differential Scanning Calorimetry (abbreviated internationally DSC) is 90 ° C. The phosphorus content is 4.47%, the content of bis (2,6-dimethoxybenzoyl) -2,4 oxide. 4-trimethylpentylphosphine is 71% and that of a-hydroxycyclohexylphenyl ketone is 29%, which is determined by high pressure liquid chromatography (HPLC) X-ray structural analysis (measured in a platelet-shaped crystal) yellow with use of a 4 circles diffractometer Philips PWllOO, MoKa, radiation (? = 0-70926 Á), calculated by direct methods using the SHELX86 program system (Sheldrick, Gottingen), indicates a system of monoclinic crystals that has a group of space P2? / C (International Tables for Crystallography with rays X, 1974, Volume IV). Formula C6H307P • C? 3H? 602; molecular weight 694.80. The unit cell contains 4 molecules and its dimensions are as follows: a (A) 17,514 (2); b (A) 10,518 (1); c (A) 20,912 (2); ß (°) 97.92 (1); V (A3) 3815.5 (8). The refinement calculation gives a value of R of 0.047. Example 2: Molecular complex of bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine and a-hydroxycyclohexylphenyl ketone oxide. The crystals are prepared for seeding according to what has been described in Example 1. 140 g of bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and 60 g of a-hydroxycyclohexylphenyl ketone are dissolved. at a temperature of 30 to 35 ° C in a mixture of 92 g methyl ethyl ketone (MEK) and 11 g of water.

(The presence of water here is not mandatory, the complex is also obtained if pure MEK is used). The solution is cooled to 20 to 23 ° C and sown with the correct modification of mixed crystals. As soon as a clear suspension of crystals has formed, as it is slowly diluted with 500 ml of water. A filtration at 20 ° C produces 220 g of a moist product that is washed with water and dried at about 70 ° C and 50 mbar to give 200 g, that is, more than 99% of the theory, of a crystalline product dry which has a melting point of 91 ° C (DSC).

The content of the bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide is 71%, and that of the α-hydroxycyclohexylphenyl ketone is 29% (HPLC). Example 3: Molecular complex of bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentyl phosphine and 2-hydroxy-2-methyl-1-phenylpropan-1 -one oxide. Seed crystals are prepared by dissolving the components in a molar ratio of 1: 1 in ethyl acetate at room temperature. The crystallization is carried out by the addition of hexane. A mixture of crystals of molecular complexes consisting of the oxide of bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine and of 2-hydroxy-2-methyl-1-phenylpropan-1-one and crystals is formed. They consist of bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide. This mixture of crystals is suitable as a seed crystal in the preparation of larger amounts of crystals of the molecular complex. Preparation of larger quantities of the crystals of the molecular complex: 150 g of bis (2,6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide and 50 g of 2-hydroxy-2-methyl-1-phenylpropane are dissolved. l-one at a temperature of 30 to 35 ° C in a mixture of 92 g of methyl ethyl ketone and 11 g of water. (The presence of water is not mandatory here, the complex is also obtained when pure MEK is used). The solution is cooled to 5 ° C and sown with the corresponding modification of mixed crystals. As soon as a clear crystal suspension has formed at 5 ° C, it is slowly diluted with 1000 ml of water. Filtration is done at 20 ° C and drying at approximately 60 ° C and a pressure of 50 mbar generates 194 g of dry crystalline product, ie 97% of the theory, which has a melting point of 73 ° C (DSC) and a phosphorus content of 4.7%. The structural analysis with X-rays (measured on a colorless platelet-shaped crystal with the use of a Philips PWllOO four cycle diffractometer, MoKa, radiation (? = 0.70926 A), calculated using direct methods with the SHELX86 program system (Sheldrick, Gottingen), indicates a monoclinic crystal system that has the space group P2? / N (International Tables for Crystallography with X-Rays, 1974, Volume IV) Formula C26H35? 7P • C? OH? 202; Molecular 654.73 The unit cell contains 4 molecules and its dimensions are as follows: a (A) 17.828 (2); b (A) 10.365 (1); c (A) 19.592 (2); ß (°) 95.46 (1 ); V (A3) 3603.9 (8) The calculation is about the refinement gives an R value equivalent to 0.042 Example 4: Molecular complex of bis (phenyl) -2,4,6-trimethylbenzoyl phosphine oxide and a- hydroxycyclohexyl-phenyl ketone Seed crystals are prepared by very slow cooling of a bis (phenyl) -2,4,6-trim oxide solution ethylbenzoylphosphine and a-hydroxycyclohexylphenyl ketone in a molar ratio of 1: 1 in Isopar E® (straight and branched chain paraffinic hydrocarbon mixture; ESSO).

Preparation of larger amounts of crystals of molecular complexes. 100 g of bis (phenyl) -2,4,6-trimethylbenzoylphosphine oxide and 59 g of a-hydroxycyclohexylphenyl-ketone are dissolved at 80 ° C in 200 ml of Isopar E®. The resulting solution is cooled to 55 ° C during which time a cloudy emulsion forms. This emulsion is seeded at 53 to 55 ° C with the corresponding modification of the mixed crystal. The product crystallizes in the form of pale yellow crystals, hard. The resulting suspension is cooled to room temperature at a uniform rate in the course of 2 to 3 hours and then filtered. The filter cake is washed first with Isopar E® and then with hexane. Drying at 50 ° C and under 50 millibars generates 150 g of the product corresponding to 94.3% of the theory. The melting point is 69.4 ° C (DSC), and the phosphorus content is 5.5%. X-ray structural analysis (measured using a Philips PWllOO four-circle diffractometer, MoKa, radiation (? = 0.70926 A), calculated by direct methods using the SHELX86 program system (Sheldrick, Gottingen), indicates a system of triclinic crystals that has the group of space Pl, centrosimético (N ° 2 in the International Tables for Crystallography with X-Rays, 1974, Volume IV) .Formula C22H2? 02P • d3H? 602; molecular weight 552.65.

The unit cell contains 2 molecules and its dimensions are the following: a (A) 9,081; b (A) 11,436; c (A) 16,092; a (°) 91.98; ß (°) 101.05; ? (°) 109.50; V (A3) 1537.3. The refinement calculation gives an R value equivalent to 0.051. The distance between the two associated O atoms through a hydrogen bond (OH group of the hydroxyketone with the O atom in the phosphine oxide of phosphine) is 2.715 A. The bond angle O-H-0 it is measured as 160 °. Example 5: Molecular complex of bis (phenyl) -2,4-6-trimethylbenzoylphosphine oxide and a-hydroxycyclohexyl-phenylketone (fusion method). 10 g of bis (phenyl) -2,4,6-trimethylbenzoylphosphine oxide and 5.9 g of a-hydroxycyclohexylphenylcethone are melted at 100 ° C, homogenized and allowed to cool slowly to room temperature. Seeding with the corresponding molecular complex compound causes spontaneous crystallization. Example 6: Molecular complex of bis (2,4,6-trimethylbenzoyl) -2,4-dihexoxy phenyl phosphine and a-hydroxy cid ohexyl phenyl ketone oxide (fusion method). Sowing crystals are obtained by very slow cooling with a 1: 1 ratio of a molar molten mass of bis (2,4,6-trimethylbenzoyl) -2,4-diohexoxyphenylphosphine oxide and α-hydroxycyclohexylphenyl ketone, being thoroughly abraded over the wall of the bottle once the molten mixture has cooled. Preparation by crystallization: 1.5 g of bis (2,4,6-trimethylbenzoyl) -2,4-dihexoxyphenylphosphine oxide and 0.5 g of α-hydroxycyclohexylphenyl ketone are dissolved at 50 to 60 ° C in 10 ml of Isopar E® / ethyl ester (3 :1). The resulting solution is cooled to 20 to 25 ° C and seeded with seed crystals as described above. The solution is then stored overnight in a refrigerator. During this time the product crystallizes in the form of pale yellow crystals. The resulting suspension is filtered and the filter cake is washed first with cold Isopar E® and then with cold hexane. Drying at 40 to 50 ° C and a pressure of 50 mbar generates 1 g of the product (around 50% of theory). The melting point is determined by the DSC method and is 67.3 ° C. The structural analysis with X-rays (measured in a cubic crystal using a four-circle diffractometer Nonius CAD4 (Enraf Nonius), CuKa, radiation (? = L.54178 A), calculated by direct methods using the SHELX86 program system ( Sheldrick, Góttingen), indicates, a triclinic crystal system that has the group of space Pl, (International Tables for Crystallography with X-rays, 1974, Volume IV). Formula C38H5? 0P • C? 3H? 602; molecular weight 823.02. The unit cell contains 2 molecules and its dimensions are the following: a (A) 11.721 (1); b (A) 12.327 (1); c (A) 17,493 (1); a (°) 105.73 (1); ß (°) 99.32 (1); ? (°) 92.71 (1); V (Á3) 2389. 6 (3). The refinement calculation gives an R value of 0.079. The distance between the two associated O atoms by means of a hydrogen bond (OH group of the hydroxyketone with the O atom on the phosphine of the phosphine oxide) is 2.747 A. The angle of the O-H-0 bond is it measures 169 °. Example 7: Healing of a white paint. A photocurable white paint is prepared by mixing the following components: 67.5% Ebecryl® 830 5.0% hexanediol diacylate 2.5% trimethylolpropane triacrylate 25.0% titanium dioxide RTC-2® and 3.0% of the compound of the molecular complex from Example 3. The formulation is applied to chipboard using a 10 μm slotted fixed blade.

The exposure is then carried out with a medium pressure mercury lamp of 80 W / cm of the Canrad-Hanovia type (USA), passing the sample under the lamp by a band with a speed of 5 m / min. The resulting paint film is completely cured in its total thickness and is resistant to staining; its hardness by pendulum (according to Kdnig, DIN 53157) is 146 seconds.

Claims (15)

1. A molecular complex compound comprising a mono-, bis- or trisacylphosphine oxide compound with an α-hydroxyketone compound.

2. A compound of a molecular complex according to Claim 1, wherein the mono-, bis or trisacylphosphine oxide compound is a compound of the formula I Ri and R2 independently from each other are alkyl with one to twelve carbon atoms, benzyl, phenyl of the unsubstituted or substituted one to four times by halogen, alkyl with one to eight carbon atoms and / or alkoxy with one to eight carbon atoms. carbon are either cyclohexyl or a COR3 group; O well o Ri is -OR4, or a group -x-p-c-R3 R3 is phenyl, which is unsubstituted or substituted one to four times by alkyl with one to eight carbon atoms, alkoxy with one to eight carbon atoms, alkylthio with one to eight carbon atoms and / or halogen, or a group or II o II -YCPR, R, R 4 is alkyl having one to eight carbon atoms, phenyl or benzyl; Y is phenylene, alkylene with one to two carbon atoms or cyclohexylene; and X is alkylene with one to eighteen carbon atoms or a group:

3. A molecular complex compound according to Claim 1, wherein the a-hydroxyketone compound is a compound of the formula II Rn and R12 independently of each other are hydrogen, alkyl having one to six carbon atoms or phenyl, or Rn and 12 together with the carbon atom to which they are attached, form a cyclohexyl ring; R 3 is OH; Ri 4 is hydrogen, alkyl having one to twelve carbon atoms, alkoxy having one to twelve carbon atoms, -OCH 2 CH 2 -OR 5, a group CH 2 = C (CH 3) - or I is a number from two to ten; B is the radical O H, R15 is hydrogen II O C or II I 3 C-CH = CH "-C-C = CH"

4. A molecular complex compound according to Claim 1, comprising a mono- or bisacylphosphine oxide compound of the formula I O O II II R-P-C- -R, (I) in which R, Ri and R2 independently from each other are alkyl having one to twelve carbon atoms, phenyl which is unsubstituted or substituted once or twice by alkyl with one to eight carbon atoms and / or alkoxy with one to eight carbon atoms, or constitute COR3; R3 is a radical Rie is alkyl with one to four carbon atoms or alkoxy with one to four carbon atoms; and R19 is hydrogen or alkyl with one to four carbon atoms; and an a-hydroxyketone compound of formula II Rn and R12 independently of each other represent alkyl having one to four carbon atoms or Ri and R2, together with the carbon atom to which they are attached form a cyclohexyl ring; and Ri4 is hydrogen.

5. A molecular complex compound according to Claim 1 wherein the acylphosphine oxide compound is bis (2,6-dimethoxybenzoyl) (2,4,4-trimethylpentyl) phosphine oxide or 2, 4, 6 oxide. trimethylbenzoyldiphenylphosphine and the a-hydroxyketone compound is a compound in the formula II in which R n and Ri 2 are alkyl with one to four carbon atoms or R n and Ri 2, together with the carbon atom to which they are attached form a cyclohexyl ring , Ri3 is OH and Ri is hydrogen.

6. A molecular complex compound according to claim 1, wherein the acylphosphine oxide compound is the bis (2,6-dimethoxybenzoyl) 2,4,4-trimethylpentyl) phosphine oxide, bis (2, 4) oxide. 6-trimethylbenzoyl (2,4-dihexyloxy-phenyl) phosphine, bis (2,4,6-trimethyl-benzoyl) (4-ethoxyphenyl) phosphine oxide or 2,4,6-trimethylbenzoyl-diphenylphosphine oxide and the compound of a-hydroxyketone is a-hydroxycyclohexylphenyl ketone or 2-hydroxy-2-methyl-1-phenylpropan-1-one

7. A molecular complex compound according to Claim 1, which comprises the mono-, or triacylphosphine and the a-hydroxyketone compound is present in a molar ratio of 1: 1.

8. A photopolymerizable composition comprising (a) At least one photopolymerizable ethylenically unsaturated compound, and (b) As a photoinitiator, at least one molecular complex compound according to Claim 1.

9. A photopolymerizable composition according to Claim 8, comprising other additives. in addition to component (b).

10. A photopolymerizable composition according to Claim 8, containing 0.015% to 15%, in particular

0. 2% to 5% by weight of component (b) as photoinitiator.

11. A photopolymerizable composition according to claim 8, comprising as photoinitiator at least one molecular complex compound according to claim 1 and also an ultraviolet light absorber of the class of hydroxyphenyl-s-triazines and / or hydroxyphenylbenzotriazoles and / or Stereo hindered amines based on 2, 2,6,6-tetramethylpiperidines.

12. A method of photopolymerizing compounds having ethylenically unsaturated double bonds with irradiation of a composition according to Claim 8 with light in the range of 200 to 600 nm.

The use of a composition according to Claim 8 to produce paints, printing inks, printing plates, dental compositions and strength materials and as an image recording material especially for holographic records.

14. A coated substrate that is coated on at least one side with a composition according to Claim 8.

15. A method for the photographic production of enhanced images in which a coated substrate according to Claim 14 is subjected to an exposure. by images to then remove the unexposed portions with a solvent.