DE2706639A1 - REINFORCED COMPOSITES - Google Patents

Description

Dr. F. Zumstein Sr. - Dr. E. Assmann - Dr. R. Dipl.-Phys. R. Holzbauer - Dipl.-Ing. F. Klingsehsen - Dr. F. Zumstein jun.

TELEPHONE: COLLECTIVE NO. 22 53 41

TELEX 529979 TELEGRAMS: ZUMPAT

POSTSCHECKKOlVfTO: MUNICH 91139-8O9. BLZ 70O10O8O BANK ACCOUNT: BANKHAUS H. AUFHÄUSER KTO-NO. 397997. BLZ 7OO306OO ·

8 MUNICH 2.

BRAUHAUSSTRASSE 4

Case 3-10337 / AEL 251+

CIBA-GEIGT AG, CH-4002 Basel / Switzerland

Reinforced composites

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The present invention relates to a method for making reinforced composites from epoxy resins and reinforcing materials, as well as the composites thus obtained by this process.

Composite structures are generally made by using fibrous materials such as paper, glass and carbon fibers with the solution of a solid thermosetting resin and a heat-activatable hardener for the Resin impregnated, the resin can be solidified by evaporation of the solvent and, if desired, the resin mass hardens by exposure to heat. ... Composite structures can also be made from foils of a thermosetting resin compound produce by placing a sheet of the resin composition on a fibrous reinforcement and applying heat and pressure to it, so that the resin mass flows around the fibers, but remains curable, and then further heated, if desired, so that the resin mass is hardened by the heat-activated hardener.

Both of these methods have certain disadvantages. When using a solvent it is not always possible to to remove all traces of it before the final hardening. The finished composite can therefore by evaporation contain voids caused by this residual solvent. The use of solvents can also be used cause difficulties due to their toxicity or flammability, or even environmental pollution. If an adhesive film is used, it must first be removed

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a liquid thermosetting resin and is then extended to the solid state. Through a such a process increases the cost of the composite significantly. Both methods also require one considerable energy expenditure, either for solvent evaporation or for advancing the resin.

A method has now been found by which reinforcement materials can be obtained without the disadvantages of the prior art methods Impregnate with a liquid, solvent-free epoxy resin compound and quickly turn this compound into one can transfer solid, but still heat-hardenable state. In this novel process, a liquid epoxy resin compound, after it has been used to impregnate the reinforcement material, by exposure to actinic Radiation photopolymerized in the presence of a photopolymerization catalyst, but not heat-crosslinked, and the like The resulting prepreg is, if desired, cured by heating over remaining epoxy groups to form the composite to build.

The present invention accordingly provides a method for the production of prepregs, which thereby is marked that one

i) a fibrous reinforcing material with a liquid Composition containing an epoxy resin and a photopolymerization catalyst therefor, as well as a heat-activated one Crosslinking agent for epoxy resins impregnated and ii) the impregnated material with actinic radiation so

7 0 ü; -; / 0 9 0 D - 3 -

exposed that the mass by photopolymerization of the Epoxy resin solidified via its epoxy groups, but the resin remains essentially in the heat-curable state.

The invention also relates to prepregs produced by the process according to the invention.

The invention also relates to a method for producing a reinforced composite which is characterized in that a photopolymerized, but still heat-curable prepreg according to the invention hot-hardened, as well as reinforced composites produced by this process.

Reinforcement can be in the form of woven or unwoven arcs, rectified lengths, or chopped Strands are present and made of natural or synthetic fibers, in particular glass, boron, stainless steel, tungsten, Silicon carbide, asbestos, an aromatic polyamide or carbon.

The compositions used for the production of the prepregs according to the invention must be below those used in the production of these The conditions applied to prepregs are liquid, but are preferably solvent-free.

Epoxy resins that can be used in these compositions, i.e. substances that contain more than one 1,2-epoxy group per average molecule are preferably those with groups directly bonded to oxygen, nitrogen or sulfur atoms

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formula

-CH-C- CH

II ₁ U ι

RR ^R

ρ
wherein either R and R each represent a hydrogen atom, in which case R is a hydrogen atom or a methyl group

2
represents, or R and R together represent -CHpCHp-, in which case R represents a hydrogen atom.

Examples of such resins are polyglycidyl and poly (β-methylglycidyl) esters, which are obtained by reaction a compound containing two or more carboxylic acid groups per molecule with epichlorohydrin, glycerol dichlorohydrin or ß-methylepichlorohydrin can be obtained in the presence of alkali. Such polyglycidyl esters can be derived from aliphatic polycarboxylic acids, e.g. succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, Sebacic acid or dimerized or trimerized linoleic acid; of cycloaliphatic polycarboxylic acids such as tetrahydrophthalic acid, 4-methyltetrahydrophthalic acid, hexahydrophthalic acid and 4-methylhexahydrophthalic acid; and from Derive aromatic polycarboxylic acids such as phthalic acid, isophthalic acid and terphthalic acid.

Further examples are polyglycidyl and poly (ßmethylglycidyl) ethers, by reacting at least two free alcoholic and / or phenolic hydroxyl groups per molecule containing compound with the corresponding epichlorohydrin under alkaline conditions, or in

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Presence of an acidic catalyst followed by alkali treatment. These ethers can be mixed with poly (epichlorohydrin) from 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 , Butane-1,4-diol, poly (oxytetramethylene) -glycols, pentane-1,5-diol, hexane-1,6-diol, hexane-2,4,6-triol, glycerine, 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) cyclohex-3-ene; and from alcohols with aromatic nuclei such as N, N-bis (2-hydroxyethyl) aniline and p, p ^f -bis (2-hydroxyathylamino) diphenylmethane. They can also be obtained from mononuclear phenols such as resorcinol and hydroquinone, and polynuclear phenols such as bis (4-hydroxyphenyl) methane (ie bisphenol F), 4,4'-dihydroxydiphenyl, bis (4-hydroxyphenyl) sulfone, 1, 1,2,2-tetrakis- (4-hydroxyphenyl) -ethane, 2,2-bis- (4-hydroxyphenyl) -propane (i.e. bisphenol A) and 2,2-bis- (3,5-dibromo-4- hydroxyphenyl) propane, as well as from aldehydes such as formaldehyde acetaldehyde, chloral and furfural with phenols such as phenol itself and by chlorine atoms or alkyl groups with up to nine carbon atoms each ring-substituted phenol such as 4-chlorophenol, 2-methylphenol and 4-tert-butylphenol .

Poly (N-glycidyl) compounds include, for example

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wise derivatives of at least two amino hydrogen atoms containing Amines such as aniline, n-butylamine, bis (4-aminophenyl) methane and bis (4-methylaminophenyl) methane; Triglycidyl isocyanurate; and Ν, Ν'-diglycidyl derivatives of cyclic alkylene ureas such as ethylene urea and 1,3-propylene urea, and hydantoins such as 5,5-dimethylhydantoin. Poly (N-glycidyl) compounds are not preferred in the case that it is photopolymerization or thermal crosslinking stage is the reaction with a Lewis acid.

Poly (S-glycidyl) compounds are, for example Di-S-glycidyl derivatives of dithiols such as ethane-1,2-dithiol and bis (4-mercaptomethylphenyl) ether.

Examples of epoxy resins with one or more

2 groups of the formula I, in which R and R together one

₂ p are bis (2,3-epoxycyclopentyl) -ether, 2,3-epoxycyclopentyl-glycidylether and 1,2-bis- (2,3-epoxycyc1openty1oxy) -ethane.

Also suitable are epoxy resins in which the 1,2-epoxy groups are bonded to heteroatoms of various types are, for example the Ν, Ν, Ο-triglycidyl derivative of 4-aminophenol, the glycidyl ether / glycidyl ester of salicylic acid, l-glycidyl-3- (2-glycidyloxypropyl) -5,5-dimethylhydantoin and 2-glycidyloxy-1,3-bis (5,5-dimethyl-1-glycidylhydantoin-3-yl) propane.

It is also possible to use epoxy resins in which some or all of the epoxy groups are in the middle, such as

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Vinylcyclohexendioxyd, Limonendioxyd, Dicyclopentadiendioxyd, 4-Oxatetracyclo [6,2,1,0 ² * ⁷ 0 ^{3 "5]} undec-9-yl glycidyl ether, the bis (4-oxatetracyclo [6,2, LF0 ^{2 '7} , 0 ³ ' ⁵ ] undec-9-yl) ether of ethylene glycol, the 3,4-epoxycyclohexylmethyl ester of 3 »^' - epoxycyclohexanecarboxylic acid and its 6,6'-dimethyl derivative, the bis (3,4-epoxycyclohexanecarboxylic acid ester) des Ethylene glycol, 3- (3,4-epoxycyclohexyl) -8,9-epoxy-2,4-dioxaspiro [5,5] undecane and epoxidized butadienes or copolymers of butadiene with ethylene compounds such as styrene and vinyl acetate.

Il

If necessary, you can use epoxy resin mixtures use.

For the use according to the invention, polyglycidyl ethers, especially those of polynuclear phenols such as bisphenol A and F are preferred.

Suitable photopolymerization catalysts for use in the process according to the invention are other o-alkylnitrobenzenes, organohalogen compounds, certain chromates and dichromates as well as aromatic "onium" salts, in particular diazonium salts, which split off a Lewis acid on exposure to actinic radiation.

Suitable aryldiazonium compounds include the fluoroborates of formula II or III

A =? C ^N 2 ^BF 4

in ^R

3 4 5

wherein R, R and R ^ independently of one another are hydrogen or

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/ Γ

Represent halogen atoms or alkyl, alkoxy, aryl, nitro or sulfonyl groups. Such fluoroborates and their use for the light-induced polymerization of epoxides are described in U.S. U.S. Patent No. 3,205,157.

Other commercially available diazonium fluoroborates that can be used correspond to the formula

IV

wherein R and R have the meaning given above, Q for an oxygen or sulfur atom or an imino group (-NH-) and R and R 'independently of one another for alkyl groups or together with the nitrogen atom to which they are attached, a saturated or unsaturated 5- or 6-membered one heterocyclic radical, which can contain an oxygen or sulfur atom or a second nitrogen atom, stand.

Particularly suitable diazonium fluoroborates are diphenylamine-4-diazonium fluoroborate, 2, S-diethoxy- ^ morpholinobenzene diazonium fluoroborate, 2,5-diethoxy-4- (p-tolylthio) -benzenediazonium fluoroborate, 4- (diethylamino) benzene diazonium

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fluoroborate, 3-methoxy-4-pyrrolidinobenzene diazonium fluoroborate iind 4-morpholinobenzenediazonium fluoroborate.

Still other suitable aryldiazonium compounds are those of the formula

VI nt

where R is a halogen atom or a nitro, N-morpholino, alkyl, alkoxy, aryl, amino, arylamino, alkylamino or aryl mercapto group, η is the oxidation number of M and m is the number of diazonium groups in the diazonium salt and MX _{n stands} for hexachlorostannate, tetrachloroferrate, hexafluorophosphate, hexafluoroarsenate, hexachlorantimonate, hexafluoroantimonate or pentachlorobismuthate.

These compounds and their use for photopolymerization of epoxides are described in British Patent No. 1,321,263.

Suitable o-alkylnitrobenzenes are those of the formula

VII R ⁹

, ~ CH.

^ "" ^ VII

NO ₂

9 10
wherein R and R each for a hydrogen atom or an alkyl, aryl, carbalkoxy, pyridyl, carbazolyl, N-oxidopyridyl, nitroalkyl, nitroaryl, alkaryl, aralkyl, haloalkyl or haloaryl group and R. for a hydrogen atom or an alkyl, aryl, nitroalkyl, nitroaryl, alkaryl, aralkyl, haloalkyl or haloaryl group.

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Such nitrobenzenes and their use for the photopolymerization of epoxides are described in the German patent application No. 2,361,141.

Mixtures of an organohalogen compound containing alkyl, aryl, alkaryl, aralkyl, alkoxy or aryloxy groups with an organometalloid compound of the formula

(R ¹² ) ₃ E VIII

where E is a phosphorus, antimony, arsenic or bismuth atom

12th
represents _/ and the R each stand for a hydrogen atom or a hydrocarbon group in such a way that min-

12th
at least one R group is a hydrocarbon group, for example a mixture of iodoform and triphenyl bismuthine, as well as their use for the photopolymerization of epoxides, are described in yS Patent No. 3,895,954.

The use of an alkali metal, alkaline earth metal or ammonium chromate or dichromate or a polyhalogenated one organic compound, which at a relatively low valence dissociation energy is a free Halogen radical provides, such as iodoform, carbon tetrabromide, tetrabromo-o-cresol, a tetrachlorobenzene, a tetrabromobutane or carbon tetrachloride, for the photopolymerization of epoxides is disclosed in U.S. U.S. Patent No. 3,782,952.

^Ll as aromatic onium "salts, which release a Lewis acid upon exposure to actinic radiation, are also suitable aromatic salts of elements from groups VA and VIA of the Periodic Table such as aromatic ammonium,

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Arsonium, phosphonium, sulfonium and selenonium tetrafluoroborates and hexafluorophosphates, as well as aromatic ones Halonium salts such as aromatic iodonium tetrafluoroborates, -hexafluorophosphates, -hexafluoroantimonates, -hexachlorantimonates, -tetrachlorostannate, -tetrachlorferrate, -pentachlorobismutate, bisulfates, nitrates and hexafluoroarsenates. Preferred aromatic groups are phenacyl and phenyl groups, and triphenylsulfonium or diphenylethylsulfonium tetrafluoroborate, Triphenylsulfonium and Diphenyläthylsulfoniumhexaf luorpho spha t as well as Triphenylphenacylphosphoniumfluorborat are particularly preferred.

Such compounds and their use for the photopolymerization of epoxides are in the Belgian Patent specifications No. 828 668, 828 669 and 828 670 as well as in the German Auslegeschrift No. 2 602 574 described.

As a heat-activated crosslinking agent for the Epoxy resin is, for example, a polycarboxylic acid anhydride, dicyandiamide, a complex of boron trifluoride or boron trichloride with, for example, an amine such as a tertiary amine, a latent boron difluoride chelate, an imidazole or an aromatic Polyamine into consideration. Dicyandiamide and the complexes of boron trifluoride or boron trichloride with amines preferred because they are effective even in small proportions. The heat-activated crosslinking agent is usually prior to impregnation of the fibrous reinforcement in the liquid mass dissolved or suspended.

The amount of the photopolymerization catalyst is

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generally 0.1 to 20 parts by weight per 100 parts by weight of epoxy resin, with 1 to 10 parts by weight being preferred. The amount of the heat-activatable crosslinking agent is generally from 0.5 to 20 parts by weight, and preferably from 1 to 10 parts by weight, per 100 parts by weight of epoxy resin.

Actinic radiation with a wavelength of 200,600 is preferably used in the photopolymerization process mn. Suitable actinic radiation sources include charcoal arcs, mercury vapor arcs, Fluorescent tubes with fluorescent materials emitting ultraviolet light, argon and xenon glow lamps, tungsten lamps and photographic flood lamps. Among them are "mercury vapor arcs", especially sunlamps, fluorescent Sunlight and metal halide lamps are best suited. · The time required for exposure will depend on a number of factors including, for example, the individual epoxy resin used, the amount of resin on the reinforcement, the type of light source and its distance from the impregnated material. Those skilled in the art of photopolymerization methods can readily determine the appropriate times determine, but the product photopolymerized in this way has yet to be be heat-hardenable. The irradiation takes place naturally at a temperature below that at which extensive Hot hardening would occur.

The temperature and duration of heating required to cure the epoxy resin can be easily passed through Determine series tests and is anyway for such general

-13-

ίο

commonly available, heat-activated crosslinking agents are already well known.

Such an amount of epoxy resin, photopolymerization catalyst and thermosetting crosslinking agent is preferred that the prepreg contains 20 to 80% by weight of said constituents and correspondingly 80 to 20% by weight of reinforcement. % Of said component and 70 to 50 wt .- # gain used - are particularly preferred total of 30 to 50 wt..

Prepregs produced according to the invention can be provided in the form of flat sheets or shaped bodies. . Is a hollow molded body is required, so it is particularly convenient to use a continuous cable of fibrous reinforcing material impregnate and wind the cable around a bobbin with simultaneous exposure to actinic radiation. Such windings still have a certain degree of flexibility, which allows the bobbin to be removed more easily, than would be possible with a rigid coil formed in one step. If desired, you can use the Heat the thread winding to complete the hardening process.

The following examples illustrate the invention. The temperatures are degrees Celsius, and the parts are Parts by weight, unless otherwise stated. The epoxide contents are determined by titration against Ο, ΐη-perchloric acid solution in glacial acetic acid in the presence of excess tetraethylammonium bromide determined using crystal violet as an indicator. All specified interlaminar

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Shear strengths represent the average of three results and were determined using ASTM method D 2344-72 certainly.

EXAMPLE 1

Diphenylamine-4-diazonium fluoroborate (5 parts) is added and dicyandiamide (3 parts) to 2,2-bis (4-glycidyloxyphenyl) propane (100 parts) with an epoxide content of 5.2 eq / kg. This liquid mass is used to manufacture a prepreg by impregnating glass cloth (rectangular fabric) with it and then the cloth on both sides for 60 seconds with a 500 W medium pressure mercury lamp exposed at a distance of 15 cm.

A 6-fold glass cloth laminate is produced by that six 15 cm square pieces of prepreg are pressed for 1 hour at 170 and a pressure of 2.1 MN / m. This laminated body, consisting of 37.5% resin and 62.5% glass, has an interlaminar shear strength of

15.2 MN / m. After immersing the laminate for 2 hours in boiling water, its interlaminar shear strength is

still 13.0 MN / m.

EXAMPLE 2

Diphenylamine-4-diazonium fluoroborate (5 parts) is added and n-octyldimethylamine / boron trichloride complex (4 parts) 100 parts of 2,2-bis (4-glycidyloxyphenyl) propane (epoxide content 5.2 eq / kg). This liquid mass is, as in Example 1 described, used to produce a prepreg.

A 6-ply glass cloth laminate is made by placing six 15 cm square pieces of prepreg

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1 hour at 120 ° and a pressure of 2.1 MN / m pressed. This laminated body consisting of 38.596 resin and 61.5% glass has an interlaminar shear strength of 14.8 MN / m ² .

EXAMPLE 3

Triphenylphenacylphosphonium fluoroborate (5 parts) and dicyandiamide (4 parts) are added to form a mixture 60 parts of 2,2-bis (4-glycidyloxyphenyl) propane (epoxide content 5.2 eq / kg) and 40 parts of vinyl-4-cyclohexenedioxide (epoxide content 6.8 eq / kg). This liquid mass is then, as described in Example 1, used to produce a prepreg, except that the impregnated glass cloth is irradiated for 10 minutes.

A six-part glass cloth composite is, as in example 1 described, produced. This made of 24% resin and A 76% glass composite has an interlaminar Shear strength of 7.4 MN / m.

EXAMPLE 4

One impregnates one made of poly (p-phenylene terephthalamide) fibers existing tissue with a mass of 100 parts diglycidyl hexahydrophthalate (epoxide content 6.5 eq / kg), 5 parts of diphenylamine 4-diazonium fluoroborate and 5 parts Boron trifluoride / monoethylamine complex. The prepreg is heated for 10 minutes using a high pressure metal halide quartz lamp irradiated, the radiation of which is predominantly in the 365 ΐημ band. A six-layer body is produced from the prepreg by making six 15 cm square pieces

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pressed at 2.1 MN / m ^{2 for} 1 hour at 120 ° and 1 hour at 150 °. Similarly, one could use poly (m-phenylene isophthalic amide) fibers.

EXAMPLE 5

Unidirectional carbon fibers are impregnated with a mass of 100 parts of diglycidyl hexahydrophthalate, 30 parts of bis (4-aminophenyl) methane and 5 parts of diphenylamine-4-diazonium fluoroborate and then irradiated for 15 minutes with a high pressure metal halide quartz lamp at a distance of 15 cm. A triple-layer body is produced from the prepreg by being subjected to a pressure of 1.4 MN / m for 1 hour 120 ° and heated at 180 ° for 2 hours.

■ / ■

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Claims (17)

PATENT CLAIMS 1. A process for the production of prepregs, characterized in that that he i) a fibrous reinforcing material with a liquid mass containing an epoxy resin and a photopolymerization catalyst contains, and a heat-activated crosslinking agent for epoxy resins and impregnated ii) the impregnated material is exposed to actinic radiation in such a way that the mass becomes through photopolymerization of the Epoxy resin solidified via its epoxy groups, but the resin is essentially in the heat-curable state remains. 2. The method according to claim 1, characterized in that the heat-activatable crosslinking agent before Impregnation of the fibrous reinforcing material dissolves or suspends in the liquid mass. 3. Method according to claim 1 or 2, characterized in that that the photopolymerization catalyst is 0.1 to 20 parts by weight per 100 parts by weight of epoxy resin amounts to. 4. The method according to any one of the preceding claims, characterized in that the heat-activatable crosslinking agent amounts to 0.5 to 20 parts by weight per 100 parts by weight of epoxy resin. 5. The method according to any one of the preceding claims, characterized in that one actinic radiation Wavelength of 200-600 nm used. 7093 -U / 0 0Π ORIGINAL INSPECTED 6. The method according to any one of the preceding claims, characterized in that the prepreg 20 to 80 wt -.% Contains epoxy resin, photopolymerization catalyst and heat-activatable crosslinking agent. 7. Method according to one of the preceding claims, characterized in that the prepreg is made by impregnating an endless cable of fibrous reinforcing material and winding the cable around a spool with simultaneous exposure to actinic radiation manufactures. 8. The method according to any one of the preceding claims, characterized in that the fibrous reinforcing material made of glass, boron, stainless steel, tungsten, silicon carbide, Asbestos, aromatic polyamide or carbon. 9.. The method according to any one of the preceding claims, characterized in that the photopolymerization catalyst is an aromatic "onium" salt, which upon exposure to light a Lewis acid, preferably a diazonium salt, is split off with actinic radiation. 10. The method according to claim 9, characterized in that the diazonium salt of the formula 709834/0900 - 19 - n + m ■ ζ λ ς wherein R, R and R independently of one another are hydrogen or Halogen atoms or alkyl, alkoxy, aryl, nitro or sulfonyl groups, Q for an oxygen or sulfur atom or an imino group (-NH-), R and R 'individually for alkyl groups stand or together with the nitrogen atom to which they are bound for a saturated or unsaturated one 5- or 6-membered heterocyclic radical, which is an oxygen or sulfur atom or a second nitrogen atom may contain, R is a halogen atom or a 709034/0900 - 20 - Nitro, N-morpholino, alkyl, alkoxy, aryl, amino, Arylamino, alkylamino or aryl mercapto group, n is the oxidation number of M and m is the number of diazonium groups represents in the diazonium salt and MX for hexachlorostannate, Tetrachloro ferrate, hexafluorophosphate, hexafluoroarsenate, hexachlorantimonate, Hexafluoroantimonate or pentachloro bismuth is equivalent. 11. The method according to claim 9, characterized in that the photopolymerization catalyst is an aromatic Ammonium, arsonium, phosphonium, sulfonium or selenonium tetrafluoroborate or hexafluorophosphate. 12. The method according to claim 9, characterized in that the photopolymerization catalyst is an aromatic Halonium salt, preferably an aromatic iodonium tetrafluoroborate, hexafluorophosphate, hexafluoroantimonate, hexafluoroarsenate, -hexachlorantimonate, -tetrachlorostannate, -tetrachloroferrate, -pentachlorobismuthate, -bisulfate or -nitrate is. 13. The method according to any one of claims 9, 11 and 12, characterized in that the aromatic groups phenyl or are phenacyl groups. 14. The method according to any one of claims 1 to 8, characterized in that the photopolymerization catalyst is an o-alkylnitrobenzene, which is preferably of the formula 709834/0900 - 21 - ο τη
wherein R and R each represent a hydrogen atom or an alkyl, aryl, carbalkoxy, pyridyl, carbazolyl, N-oxidopyridyl, nitroalkyl, nitroaryl, alkaryl, aralkyl, haloalkyl or haloaryl group and R represents a Hydrogen atom or an alkyl, aryl, nitroalkyl, nitroaryl, alkaryl, aralkyl, haloalkyl or haloaryl group. 15. The method according to any one of claims 1 to 8, characterized in that the photopolymerization catalyst a mixture of an organohalogen compound containing alkyl, aryl, alkaryl, aralkyl, alkoxy or aryloxy groups and an organometalloid compound of the formula (R ¹² ) ₃ E. where E is a phosphorus, antimony, arsenic or bismuth atom 12th and each R is a hydrogen atom or a hydrocarbon represent a group of substances in such a way that at least 12th
an R group is a hydrocarbon group. 16. The method according to any one of claims 1 to 8, characterized in that the photopolymerization catalyst a chromate or dichromate from an alkali metal, alkaline earth metal or ammonia or a polyhalogenated organic compound that has a relatively low valence dissociation energy provides a free halogen radical, preferably iodoform, carbon tetrabromide, carbon tetrachloride, Tetrabromo-o-cresol, a tetrachlorobenzene or a tetrabromobutane is present. 17. The method according to any one of the preceding claims, 709834/0900 - 22 - characterized in that as a heat-activatable crosslinking agent a polycarboxylic anhydride, dicyandiamide, a latent boron difluoride chelate, an aromatic polyamine, a complex of boron trifluoride or boron trichloride with an amine or an imidazole is present. 709834/0900 - 23 -