DE4102546A1 - Photopolymerisation of epoxide or cyclic- or alkyl vinyl-ether - Google Patents

Abstract

In the cationic photopolymerisation of epoxides, cyclic ethers or alkylvinyl ethers in the presence of a photoinitiator system, the system comprises a mixt. of (a) at least one radical-generating photo initiator; and (b) at least one heteroatom saline cpd. with at least one gp. of formula (I) where R = opt. substd. alkyl, alkenyl, alkynyl, hetaryl, alkenylcarbonyl, alkynecarbonyl, alkoxycarbonyl, carbamoyl, alkylsulphonyl, arylsulphonylaminosulphinyl gp. substd. cycloalkyl gp. opt. substd. hetaryl cation, provided that the max. long wavelength absorption band of the cpd. is less than 350 nm.

Description

The invention relates to a method for cationic photopolymerization of epoxides, cyclic ethers and alkyl vinyl ethers in the presence of a Photoinitiator systems.

A process for generating carbocations that are cationic Polymerization of epoxides, cyclic ethers or alkyl vinyl ethers initiate ability, is based on the transfer of electrons from free Radicals on omnium salts. Such methods are, for example described by F. A. M. Abdul Rasoul, A. Ledwith and Y. Yagci in Polymer 19, 1219 (1975), by Y. Yagci and A. Ledwith in J. Polym. Sci., Polym. Chem. Ed. 26, 1911 (1988), by Y. Yagci and W. Schnabel in Macromol. Chem. Makromol. Symp. 13/14, 161 (1988) and by H.-J. Timpe in Pure appl. Chem. 60, 1033 (1988). Usable for this procedure Free radicals rich in electrons can be obtained by photolysis or thermolysis suitable connections are generated. Onium salts that have proven to be useful for Initiation of the cationic polymerization has proven particularly suitable have z. B. diazonium salts such as p-chlorophenyldiazonium hexafluoro phosphate, iodonium salts such as diphenyl iodonium hexafluorophosphate and Triarylsulfonium salts such as triphenylsulfonium hexafluoroarsenate.

The photoinitiator systems mentioned above contain, in addition to the onium salt either photochemical α-splitters, such as. B. benzil dimethyl ketal (H. Baumann and H.-J. Timpe, J. Prakt. Chem. 326, 529 (1984)), the form colored photolysis products or contain long-wave absorbers based sensitizers such. B. Thioxanthones. The disadvantage is that so that only thin layers can be hardened cationically. When used triarylsulfonium salts become malodorous when irradiated Mercaptane formed the use of the radiation-curable mixture in the Exclude food area.

The object of the present invention is to provide a method for cationic Polymerization of epoxides, cyclic ethers and alkyl vinyl ethers to show, in which by means of new photoinitiator systems advantages compared to the already known photoinitiator systems.

Surprisingly, this problem is solved by using it a combination of radical-supplying initiator and certain hetero aromatic salt-like compounds.  

The present invention relates to a method for the cationic Photopolymerization of epoxides, cyclic ethers or alkyl vinyl ethers in the presence of a photoinitiator system which is characterized that as a photoinitiator system, a mixture of

• a) at least one radical-providing photoinitiator and
• b) at least one grouping of the general formula

is used, in which R is an optionally substituted alkyl, Alkenyl, alkynyl, hetaryl, alkenylcarbonyl, alkyne carbonyl, alkoxy carbonyl, carbamoyl, alkylfulfonyl, arylsulfonylaminosulfinyl radical, a substituted cycloalkyl radical or an optionally substituted ized, hetaryl cation, with the proviso that the maximum of long-wave absorption band of this heteroaromatic salt-like ver bond is less than 350 nm.

Acylphosphine is preferred as the radical-providing photoinitiator (a) oxide compounds, bisacylphosphine oxide compounds and 6-acyl-6H-di- benz [c, e] [1,2] oxaphosphorin-6-oxides.

However, suitable radical-supplying photoinitiators are, for example also benzoin ethers and lower alkyl ketals of the general formula

wherein alkyl is an alkyl radical having 1 to 4 carbon atoms and Ar¹ and Ar² are the same or different from each other and are for phenyl or for alkyl substituted with 1 to 4 carbon atoms or halogen Phenyl.

Preferred heteroaromatic salt-like compounds (b) are salts of a six-membered group containing the general formula (I) Heteroaromatics with 1 to 3 N atoms in the ring system, the nucleus-substituted ones Derivatives thereof or the benzanellated or hetarylanellated derivatives above, in particular compounds of the general formula (II)  

where R has the same meaning as in the grouping of the general Formula (I), R 'for hydrogen or one or more if appropriate substituted alkyl groups, optionally substituted phenyl groups, Alkoxy groups, vinyl groups, formyl groups, nitro groups or halo is atomic, with the radicals R or R 'also two compounds of Formula (II) can be linked together, and A⊖ for the anion of a inorganic or organic acid is provided that no anion A⊖ is present when one of the radicals R or R 'is an anionic Grouping carrying rest. Such connections are also preferred extensions of the general formula (II) in which R is an alkyl group with 1 to 6 carbon atoms or an optionally substituted alkoxycar bonyl group having 1 to 6 carbon atoms in the alkoxy group or a, optionally identically or asymmetrically substituted, N, N, -Di is alkylcarbamoyl radical, where the substituents on the nitrogen atom Carbamoyl group can also be connected to one another to form a ring. R ′ in the compounds of the general formula (II) is preferably a Hydrogen atom or one or more, optionally substituted, Alkyl groups, especially for a hydrogen atom or one or two Methyl groups. Examples of preferred heteroaromatic, salt-like Compounds (b) are N- (carbamoyloxy) pyridinium salts, N- (carbamoyloxy) - picolinium salts, N-alkoxypyridinium salts, N-aryloxylutidinium salts, N-alkoxypicolinium salts, N-alkoxylutidinium salts, N- (alkoxycarbonyloxy) - pyridinium salts, N- (alkoxycarbonyloxy) picolinium salts and N- (alkoxycar bonyloxy) lutidinium salts, each being the heteroaromatic compound Formation (b) contain a methanesulfonate, benzenesulfonate, toluene sulfonate, alkyl sulfonate, tetrafluoroborate, hexafluoroarsenate, hexa fluoroantimonate, hexafluorophosphate or trifluoromethanesulfonate anion can contain.

The advantages of the used for the inventive method Photoinitiator systems exist u. a. in that after irradiation are practically odorless and can be used in thicker layers.

The following is to be explained in detail about the method according to the invention.

The monomers to be polymerized according to the invention are epoxides, Alkyl vinyl ethers and cyclic ethers in question.  

Examples of epoxides can be: mono-1,2-epoxide, such as epichlorohydrin, Propylene oxide, cyclohexene oxide or a glycidyl ether of a monovalent Alcohol or phenol, such as n-butylglycidyl ether or phenylglycidyl ether, a glycidyl ether such as glycidyl acrylate or glycidyl methacrylate is preferred as an epoxy resin, especially one that has at least one directly group of the formula bonded to an oxygen atom

contains, wherein either R¹ and R³ each represent a hydrogen atom, in which case R² represents a hydrogen atom or a methyl group, or R¹ and R³ together represent -CH₂CH₂-, in which case R² is water Matter atom means.

Examples of such resins are polyglycidyl and poly (β-methyl called glycidyl) esters, which can be obtained by reacting two or more Carboxylic acid groups per molecule-containing compound with epichlorohydrin, Glycerol dichlorohydrin or β-methylepichlorohydrin in the presence of alkali can get. Such polyglycidyl esters can differ from aliphatic Polycarboxylic acids, e.g. B. succinic acid, glutaric acid, adipic acid, pimeline acid, suberic acid, azelaic acid, sebacic acid or dimerized or trimerized linoleic acid, from cycloaliphatic polycarboxylic acids such as Tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, hexane hydrophthalic acid and 4-methylhexane hydrophthalic acid and aromatic polycarboxylic acids, such as phthalic acid, isophthalic acid and terephthalic acid. Further Suitable polyglycidyl esters are by polymerization of the glycidyl esters of olefinically unsaturated carboxylic acids, especially glycidyl acrylate and glycidyl methacrylate.

Further examples are polyglycidyl and poly (β-methylglycidyl) ether, which by implementing at least two free alcoholic and / or phenolic hydroxyl groups per molecule containing compounds with the corresponding epichlorohydrin under alkaline conditions, or in Presence of an acid catalyst followed by alkali treatment are available. These ethers can be made with poly (epichlorohydrin) acyclic alcohols such as ethylene glycol, diethylene glycol and higher Poly (oxyethylene) glycols, propane-1,2-diol and poly (oxypropylene) - glycols, propane-1,3-diol, poly (oxytetramethylene) glycols, pentane-1,5- diol, hexane-2,4,6-triol, glycerin, 1,1,1-trimethylolpropane, pentaerythritol and sorbitol, from cycloaliphatic alcohols such as resorcite, quinite, Bis (4-hydroxycyclohexyl) methane, 2,2-bis (4-hydroxycyclohexyl) propane and 1,1-bis (hydroxymethyl) cyclohexene-3, and from alcohols with aromatic  Cores such as N, N-bis (2-hydroxyethyl) aniline and p, p'-bis (2-hydroxyethyl amino) diphenylmethane. They can also be single-core Phenols such as bis (4-hydroxyphenyl) methane (otherwise known as bisphenol F), 4,4'-dihydroxybiphenyl, bis (4-hydroxyphenyl) sulfone, 1,1,2,2-tetrakis (4-hydroxyphenyl) ethane, 2,2-bis (4-hydroxyphenyl) propane (otherwise than Bisphenol A known) and 2,2-bis (3,5-dibromo-4-hydroxyphenyl) propane, as well as from aldehydes such as formaldehyde, acetaldehyde, chloral and furfural Phenol itself and by chlorine atoms or alkyl groups, each with up to nine carbon atoms ring-substituted phenol, such as 4-chlorophenol, 2-Methylphenol and 4-tert-butylphenol, Novolaken formed.

Poly (N-glycidyl) compounds can also be used, for example as N-glycidyl derivatives of amines such as aniline, n-butylamine, bis- (4-amino phenyl) methane and bis (4-methylaminophenyl) methane, triglycidylsio cyanurate and N, N'-diglycidyl derivatives of cyclic alkylene ureas such as ethylene urea and 1,3-propylene urea and hydantoins such as 5,5'-dimethylhydantoin. In general, however, these are not preferred.

You can also use poly (S-glycidyl) compounds, e.g. B. Di (S-glycidyl) derivatives of dithiols such as ethane-1,2-dithiol and bis- (4-mercaptomethylphenyl) ether, but these are not preferred either.

Examples of epoxy resins with groups of the above formula, wherein R¹ and R³ together represent a -CH₂CH₂ group, are bis- (2,3-epoxycyclo pentyl) ether, 2,3-epoxycyclopentyl glycidyl ether and 1,2-bis-2,3-epoxy cyclopentyloxy) ethane.

Epoxy resins in which the 1,2-epoxy groups are also suitable Heteroaromas of various types are bound, e.g. B. the glycidyl ether / Glycidyl ester of salicylic acid.

Also usable are epoxy resins in which some or all of the epoxy groups are middle-class, such as vinylcyclohexene dioxide, limonene dioxide, dicyclopentadiene dioxide, 4-oxatetracyclo- [6.2.1.0 ^2.7 .0 ^3.5 ] undecyl-9-glycidyl ether, 1.2 -Bis- (4-oxatetracyclo [6.2.1.0 ^2.7 .0 ^3.5 ] undecyl-9-oxy) - ethane, the 3,4-epoxycyclohexylmethyl ester of 3 ′, 4′-epoxycyclohexane carboxylic acid and its 6.6 ′ Dimethyl derivative, the bis (3,4-epoxycyclohexane carboxylic acid ester) of ethylene glycol, 3- (3,4-epoxycyclohexyl) -8,9-epoxy-2,4-dioxaspiro [5.5] -undecane as well as epoxidized butanedienes or copolymers of butadiene Ethylene compounds such as styrene and vinyl acetate.

If desired, epoxy resin mixtures can be used.  

Particularly preferred, used in the method according to the invention, optionally pre-extended epoxy resins are the diglycidyl ethers of dihydric phenols such as 2,2-bis (4-hydroxyphenyl) propane and bis- (4-hydroxyphenyl) methane, and of dihydric aliphatic alcohols, such as butane-1,4-diol.

If desired, the epoxy resin can be mixed-cured with a polyhydric alcohol, d. d. a connection with at least two alcoholics rule, preferably primary hydroxyl groups in the molecule. The polyhydric alcohol is preferably present in a sufficient amount to 0.5 to 1.5, especially 0.75 to 1.25, alcoholic hydroxyl groups per 1,2-epoxy group to deliver the epoxy resin. The polyhydric alcohol In addition to the alcoholic hydroxyl groups, it preferably contains only carbon, Hydrogen and optionally as ether oxygen or acetal or Carbonyl groups existing oxygen and halogen atoms. Also owns the polyhydric alcohol preferably has a molecular weight of at least 100 and in particular higher than 1000. Suitable polyhydric alcohols are for example poly (oxyethylene) glycols, polyoxypropylene) glycols, Poly (oxytetramethylene) glycols, polyepichlorohydrins, poly (oxyethylene) -, Poly- (oxypeopylen) -, or poly- (oxyetetramethylene) -triols, which by Polymerization of ethylene oxide, propylene oxide or tetrahydrofuran in Presence of glycerol or 1,1,1-trimethylolpropane are available, Poylcaprolactones with hydroxyl end groups, copolymers of styrene with allyl alcohol, polyvinyl alcohols, hydroxypropyl cellulose, hydroxy-containing poly vinyl acetals and partial esters of cellulose, e.g. B. a cellulose acetate butyrate.

Vinyl ethers which are cationically polymeric by the process according to the invention Can be used are vinyl ethers of aliphatic monohydric alcohols fetch with 1 to 12, preferably 1 to 4 carbon atoms and the 3,4-dihydro-2H-pyranyl- (2) methyl ester of 3,4-dihydro-2H-pyran-2- carboxylic acid, isobutyl vinyl ether, methyl vinyl ether, trimethylolpropane tri vinyl ether, glycerol trivinyl ether, triethylene glycol divinyl ether, 1,4-cyclohexanedimethalol divinyl ether, the vinyl ether of ethylene glycol and Poly (oxyethylene glycols) and cyclic vinyl ethers with at least two cyclic vinyl ether groups, each part of a 3,4-dihydro-2H- form pyran core, such as the 3,4-dihydro-2H-pyranyl- (2) -methylhlester the 3,4-dihydro-2H-pyran-2-carboxylic acid and its prepolymers.

A simple example of a suitable cyclic ether is that Tetrahydrofuran.

The monomers can expediently be purified before the polymerization are, for example cyclohexene oxide by distilling off over CaH₂ under  reduced pressure, tetrahydrofuran after storage over NaOH Distill off over CaH₂, or the vinyl ether, such as. B. N-butyl vinyl ether by washing with aqueous sodium hydroxide solution (approx. 10%) and water, drying with CaCl₂ and Na₂SO₄ and distilling off over CaH2.

The photoinitiator system to be used according to the invention consists of a Mixture of

• a) at least one radical-providing photoinitiator and
• b) at least one hereroaromatic salt-like compound with at least one group of the general formula (I) where R has the meaning given above.

Acylphos in particular come as radical-forming photoinitiators (a) phinoxides and derivatives thereof in question.

As examples of suitable phosphine oxide compounds (cf. e.g. EP-A-00 07 508, EP-A-00 57 474, EP-A-00 73 413 and DE-A-31 39 984) called:

2,2-dimethyl-propionyldiphenylphosphine oxide, 2,2-dimethyl-heptanoyl-di phenylphosphine oxide, 2,2-dimethyl-octanoyl-diphenylphosphine oxide, 2,2-di methyl-nonanoyl-diphenylphosphine oxide, 2,2-dimethyl-octanoyl-phenylphos methylphonic acid, 2-methyl-2-ethyl-hexanoyl-diphenylphosphine oxide, 1-methyl-1-cyclohexanecarbonyl-diphenylphosphine oxide, 2,6-dimethylbenzoyl- diphenylphosphine oxide, 2,6-dimethoxybenzoyl-diphenylphosphine oxide, 2,6-di chlorobenzoyl-diphenylphosphine oxide, 2,6-dimethoxybenzoyl-phenylphosphone acid methyl ester, 2,4,6-trimethylbenzoyl-diphenylphosphine oxide, 2,4,6-tri methylbenzoyl-phenylphosphonic acid methyl ester, 2,3,6-trimethylbenzoyl-di phenylphosphine oxide, 2,3,5,6-tetramethylbenzoyl-diphenylphosphine oxide, 2,4,6-trimethoxybenzoyl-diphenylphosphine oxide, 2,4,6-trichlorobenzoyl-di phenylphosphine oxide, 2-chloro-6-methylthiobenzoyl-diphenylphosphine oxide, 2,4,6-Trimethylbenzoyl-naphthylphosphinic acid methyl ester, 1,3-dimethoxy paphthaline-2-carbonyl-diphenylphosphine oxide, 2,8-dimethoxynaphthalene-1 carbonyl-diphenylphosphine oxide, 2,4,6-trimethylpyridine-3-carbonyl-di phenylphosphine oxide, 2,4-dimethylquinoline-3-carbonyl-diphenylphosphine oxide, 2,4-dimethoxyfuran-3-carbonyl-diphenylphosphine oxide and 2,4-dimethylfuran 3-carbonyl-phenylphosphonic acid methyl ester.

As examples of suitable bisacylphosphine oxides (see, for example, DE-A-36 33 436) are mentioned:

Bis (2,6-dichlorobenzoyl) phenylphosphine oxide,
Bis (2,6-dichlorobenzoyl) -2,5-dimethylphenylphosphine oxide,
Bis (2,6-dichlorobenzoyl) -4-ethoxyphenylphosphine oxide,
Bis (2,6-dichlorobenzoyl) -4-chlorophenylphosphine oxide,
Bis (2,6-dichlorobenzoyl) -4-propyl-phenyl-phosphine oxide,
Bis (2,6-dichlorobenzoyl) -4-biphenylphosphine oxide,
Bis (2,6-dichlorobenzoyl) -4-biphenylphosphine oxide,
Bis (2,6-dimethoxybenzoyl) -2,5-dimethylphenylphosphine oxide,
Bis (2,6-dimethylbenzoyl) phenylphosphine oxide,
Bis (2,6-dichloro3,4,5-trimethoxybenzoyl) -2,5-dimethylphenylphosphinox-id,
Bis (2-methyl-1-naphthoyl) phenylphosphine oxide,
Bis (2-methyl-1-naphthoyl) phenylphosphine oxide,
Bis (2-methyl-1-naphthoyl) -4-bisphenylyl phosphine oxide,
Bis (2-methoxy-1-naphthoyl) -2,5-dimethylphenylphosphine oxide,
Bis (2-methoxy-1-naphthoyl) -4-ethoxyphenylphosphine oxide.

Suitable 6-acyl- (6H) -dibenz [c, e] [1,2] oxaphosphorin-6-oxides are included for example listed in DE-A-38 27 735 and in EP-A-03 04 782.

However, the radical-providing photoinitiators (a), for example also benzoin ethers of the formula

such as B. benzoin methyl ether, benzoin ethyl ether, benzoin n-propyl ether, Benzoin isopropyl ether, benzoin n-butyl ether, benzoin isobutyl ether, Benzoin amyl ether or benzoin hexyl ether, and lower alkyl ketals of the general formula

wherein alkyl is an alkyl radical having 1 to 4 carbon atoms, such as. B. Methyl, ethyl, propyl, isopropyl, n-butyl and i-butyl - with the alkyl residues can be the same or different from each other -, and Ar¹ and Ar² are the same or different from each other and are phenyl or for by alkyl having 1 to 4 carbon atoms or halogens, such as chlorine  or bromine substituted phenyl such as tolyl, chlorophenyl or bromophenyl stand, are used. Benzil is an example of lower alkyl ketals called dimethyl ketal. Attention is also drawn to EP-A-02 42 330 in similar radical-providing compounds are listed.

b) As heteroaromatic salt-like compounds with at least one Grouping of the general formula (I)

where R has the meaning given above, come in particular six link heteroaromatic rings with one, two or even three rings nitrogen atoms, their core-substituted derivatives, including the benzanellated and hetarylanellated representatives. The The term salt-like compound also includes inner salts, i.e. ionic compounds in which the cationic and anionic Groups are linked together by covalent bonds.

Suitable heteroaromatic salt-like compounds (b) are in particular special the pyridinium, pyrazinium and pyrimidinium salts, which in heteroaromatic ring a grouping of the above Contain formula (I) incorporated, furthermore the core-substituted derivatives of these salts, the one or more core substituents of the above given type in the heteroaromatic ring, as well as anellier te derivatives of these salts, such as. B. benzanellated pyridinium salts core-substituted, quinolinium, isoquinolinium and phenanthri dinium salts. In the general formula (I), R can represent a optionally substituted, alkyl radical and for a cycloalkyl rest stand. Preferred for the radical R in the grouping of Formula (I) are alkyl radicals, especially alkyl groups with 1 to 6 carbon atoms.

The preferred core substituents for these salts include in particular the optionally substituted alkyl radicals. As anions for this Salts are u. a. preferably benzenesulfonate, tosylate, alkylsulfonate, Trifluoromethanesulfonate or tetrafluoroborate anions. As special advantageous for the use according to the invention N-alkoxy and N-aryloxypyridinium salts, the N-alkoxy and N-aryloxy picolinium salts as well as the N-alkoxy and N-aryloxylutidinium salts proven.  

Examples of compounds (b) with groupings of the formula (I) are

In these formulas (III) to (XI), the radical R preferably denotes one Alkyl radical with 1 to 6 carbon atoms, such as the methyl, ethyl or i-propyl group. The radical R 'in these formulas means hydrogen (corresponding to an unsubstituted heteroaromatic ring) or one or several core substituents of the type indicated above. Preferred R 'is hydrogen or one or more, if appropriate substituted, alkyl groups, aryl groups, alkoxy groups or chlorine. In particular, R 'represents a hydrogen atom or one or more methyl groups, preferably 2-methyl, 2,6-dimethyl, or in the formulas (III), (IV) and (IX) also represent 3,5-dimethyl. In formula (IX) R '' represents one Alkylidene radical, in particular with 2 to 6 carbon atoms or one Xylidene residue, e.g. B. the p-xylidene residue. The formulas (III) to (XI) A⊖ for an acid anion, the benzenesulfonate, p-toluenesulfonate, Tetrafluoroborate, trifluoromethanesulfonate, hexafluorophosphate, hexafluoro antimonate and hexafluoroarsenate are preferred.

Compounds of the formula (III) are of particular importance, where especially the compounds have proven to be particularly advantageous in which the radical R 'is a hydrogen atom or one or two methyl groups and the radical R is an alkyl group with 1 to 3 carbon atoms, such as methyl, Represents ethyl or i-propyl.

Examples of compounds (b) are:

N-methoxy-2-picolinium hexafluoroarsenate
N-methoxy-2-picolinium methyl sulfate,
N-methoxy-2-picolinium methanesulfonate,
N-methoxy-2-picolinium trifluoromethanesulfonate,
N-methoxy-2-picoline n-octyl sulfonate,
N-methoxy-2-picolinium-o / p-dodecylbenzoyl sulfonate,
N-methoxy-2-picolinium hexafluoroantimonate,
N-methoxy-2-picolinium methanesulfonate,
N-ethoxy-2-picolinium tetrafluoroborate,
N-ethoxy-2-picolinium p-toluenesulfonate,
N-ethoxy-2-picolinium tetrafluoroborate,
N-ethoxy-2-picolinium hexafluorophosphate,
N-ethoxy-2-picolinium hexachloroantimonate,
N-isooropoxy-2-picolinium p-toluenesulfonate,
O- (2′-picolinium-1′-yl) -3-hydroxy-hexafluoroarsenate,
N-methoxy-4-picolinium methanesulfonate,
N-methoxy-4-picolinium trifluoromethanesulfonate,
N-methoxy-4-picolinium p-toluenesulfonate,
N-ethoxy-4-methoxypyridinium tetrafluoroborate,
1,4-dimethoxy-pyridinium tetrafluoroborate,
N-tert-butoxy-pyridinium perchlorate,
N-methoxy-3,5-lutidinium p-toluenesulfonate,
N-methoxy-2,6-lutidinium methanesulfonate,
N-methoxy-2,6-lutidinium trifluoromethanesulfonate,
N-methoxy-2,6-lutidinium trifluoromethanesulfonate,
N-methoxy-3,5-lutidinium p-toluenesulfonate,
N-methoxy-3,5-lutidinium hexachloroantimonate,
N-ethoxy-2,5-lutidinium tetrafluoroborate,
N-ethoxy-2,6-lutidinium hexachloroantimonate,
N-ethoxy-2,6-lutidinium hexafluorophosphate,
O- (2 ′, 6′-lutidinium-1′-yl) -3-hydroxy-propanesulfonate,
N-methoxy-2-stylylpyridinium p-toluenesulfonate and
N, N'-p-xylylenoxy-bis- (2-methylpyridinium) bis (hexafluoroarsenate).

The heteroaromatic compounds (b) of the type described above can be according to the usual and common methods known from the literature or produce in analogy to these. Please be referred in this context e.g. B. on R. A. Abramovitch and E. M. Smith in "Pyridine and its Deriva tives ", Vol. 14 Supplement, Part 2, page 1 ff, J. Wiley, New York (1974).

1-ethoxy-2-methylpyridinium hexafluorophosphate (EM⊕PF₆⊖) can for example, also after that of C. Reichardt in Chem. Ber. 99, 1769 (1966).

For the process according to the invention for cationic photopolymerization the radical-providing photoinitiators (a) are generally in Amounts from 0.05 to 10, preferably 2 to 8 percent by weight heteroaromatic salt-like compounds (b) generally in amounts from 1 to 15, preferably 2 to 10 percent by weight, the Weight percentages each of the radioactive monomers (i.e. epoxy, cyclic Obtain ether or alkyl vinyl ether) used.

Actinic is preferably used in the photopolymerization process Radiation with a wavelength of 200 to 600 nm. As actinic radiation Sources are suitable, among other things, carbon arcs, mercury vapor light sheets, fluorescent tubes with phosphors that emit ultraviolet light, Argon and xenon glow lamps, tungsten lamps and photographic flood lamps. These include mercury vapor arcs, especially sunlamps, fluorescent sunlamps and metal halide lamps are the most suitable. The time required for exposure depends on various factors, among other things, for example, the polymerizable used in each case Substrate, the type of light source and its distance from the irradiated Material. The expert familiar with photopolymerization methods can easily determine suitable times. If it is necessary to do so  photopolymerized product when heated with a blended hot is harder still curable, then the radiation must of course at one Temperature below that at which the hot curing of the photopolymerized product would enter through the hot hardener, respectively.

The mixtures according to the invention are ver as surface coatings reversible. You can, preferably as a liquid, on a substrate such as Apply and irradiate steel, aluminum, copper, paper or wood. Part of the coating is polymerized, as in the case of irradiation through a mask, you can use a Wash solvent to remove unpolymerized parts while ver the photopolymerized, insoluble fractions in place stay. The compositions of the invention are thus in the Production of printing plates and printed circuits can be used.

The mixtures can also be used as adhesives. A layer of Composition can be between two surfaces of objects, one of which at least one is permeable to actinic radiation, e.g. B. glass, a brought, and the structure is then irradiated and, if desired heated to complete the polymerization.

The blends are also in the manufacture of fiber reinforced Composites, including sheet molding compounds, can be used.

The parts and percentages mentioned in the examples are, if not otherwise stated, parts by weight or percentages by weight.

Example 1

A curable composition was prepared by making one Mixture of 0.05 parts of 2,4,6-trimethylbenzoyldiphenylphosphine oxide and 0.09 parts of 1-ethoxy-2-methylpyridinium hexafluoroarsenate, dissolved in Dichloromethane, and 5 parts of 4-vinylcyclohexene dioxide.

The film became about 0.05 mm (equivalent to 2 thousandths of an inch) thick drawn on a glass plate and UV radiation from a Hg peak pressure lamp exposed from a distance of about 25 cm. The resin hardened internally half a second into a hard film. The film was in dipolar apro insoluble solvents and could not with a fingernail to be scratched.

Part of the above curable composition with a viscosity of about 6 centipoise at 25 ° C was left under average daylight  4 months in a transparent container. The visco sity remained essentially the same.

A portion of the curable composition was applied to a steel strip brought. The treated steel surface then became one for 15 seconds UV radiation from a high pressure mercury lamp from a distance of about 5 cm exposed. A clear, non-sticky film was formed that did not Showed signs of bubbles or other defects.

Examples 2 to 8

It was the experiment with other picolinium described under Example 1 salt repeatedly and the irradiation time varies so that in all Cases a scratch-resistant surface was formed.  

Examples 9 and 10

In Example 1, the 4-vinylcyclohexene dioxide is exchanged for 1,4-cyclo hexanedimethanol divinyl ether, exposure times of 25 or 20 seconds required.

Claims (15)

1. A process for the cationic photopolymerization of epoxides, cyclic ethers or alkyl vinyl ethers in the presence of a photoinitiator system, characterized in that a mixture of as photoinitiator system

• a) at least one radical-providing photoinitiator and
• b) at least one heteroaromatic salt-like compound with at least one grouping of the general formula (I) is used, wherein R is an optionally substituted alkyl, alkenyl, alkynyl, hetaryl, alkenylcarbonyl, alkyne carbonyl, alkoxycarbonyl, carbamoyl, alkylsulfonyl, aryl sulfonylaminosulfinyl radical, a substituted cycloalkyl radical or a, represents optionally substituted, hetaryl cation, with the proviso that the maximum of the long-wave absorption band of this heteroaromatic salt-like compound is below 350 nm.

2. The method according to claim 1, characterized in that as a radical delivering photoinitiator (a) an acylphosphine oxide compound is set. 3. The method according to claim 1, characterized in that as a radical delivering photoinitiator a benzoin ether is used. 4. The method according to claim 1, characterized in that as the radical-providing photoinitiator is a lower alkyl ketal of the general formula in which alkyl is an alkyl radical having 1 to 4 carbon atoms and Ar 1 and Ar 2 are identical or different from one another and are phenyl or phenyl substituted by alkyl having 1 to 4 carbon atoms or halogen. 5. The method according to any one of the preceding claims, characterized records that as a heteroaromatic salt-like compound (b) is a salt one containing six of a group of the general formula (I) membered heteroaromatics with 1 to 3 N atoms in the ring system, the core-substituted derivatives thereof or the benzanellated or hetarylanellated derivatives thereof is used. 6. The method according to any one of the preceding claims, characterized in that as a salt-like hereroaromatic compound (b) a compound of the general formula (II) is used in which R has the same meaning as in the grouping of the general formula (I), R 'for hydrogen or one or more, optionally substituted, alkyl groups, optionally substituted, phenyl groups, alkoxy groups, vinyl Groups, formyl groups, nitro groups or halogen atoms, it being possible for two compounds of the formula (II) to be connected to one another via the radicals R or R ′, and A⊖ stands for the anion of an inorganic or organic acid with the proviso that that there is no anion A⊖ if one of the radicals R or R 'represents a radical carrying an anionic grouping. 7. The method according to claim 6, characterized in that in the verb of the general formula (II) R is an alkyl group with 1 to 6 carbon atoms. 8. The method according to claim 7, characterized in that in the verb extension of the general formula (II) R an optionally substituted Alkoxycarbonyl group having 1 to 6 carbon atoms in the alkoxy group represents. 9. The method according to claim 8, characterized in that in the Ver Binding of the general formula (II), R, optionally the same or is asymmetrically substituted, N, N-dialkylcarbamoyl radical with which Provided that the substituents on the nitrogen atom of the carbamoyl group can also be connected to one another to form a ring.   10. The method according to any one of the preceding claims, characterized records that in the compound of general formula (II) R 'for a Hydrogen atom or one or more, optionally substituted, Alkyl groups. 11. The method according to claim 10, characterized in that in the verb extension of the general formula (II) R 'for a hydrogen atom or a or two methyl groups. 12. The method according to any one of the preceding claims, characterized is characterized as being a heteroaromatic, salt-like compound (b) either an N- (alkoxycarbonyloxy) pyridinium salt, or an N- (Car bamoyloxy) pyridinium salt. 13. The method according to any one of claims 1 to 11, characterized in that that they are either a heteroaromatic, salt-like compound (b) N- (carbamoyloxy) -picolinium salt or an N- (alkoxycarbonylpxy) - picolinium salt included. 14. The method according to any one of claims 1 to 13, characterized in that that the salts contained as heteroaromatic compound (b) Methanesulfonate, benzenesulfonate, toluenesulfonate, alkylsulfonate, Tetrafluoroborate, hexafluoroarsenate, hexafluoroantimonate, hexa contain fluorophosphate or trifluoromethanesulfonate anion. 15. The method according to any one of claims 1 to 14, characterized in that as a heteroaromatic salt-like compound (b) is an N-alkoxy lutidinium salt or n-aryloxylutidinium salt is used.