IE892666L - Coating agent for collagen-containing materials - Google Patents

Abstract

Collagenous material coatings containing aldehyde, unsaturated monomers with active hydrogen and unsaturated monomers without active hydrogen, solubilisers and/or dispersants, activators and additives customary per se.

Description

62648 The invention relates to formulations which can be used as a coating material, for example as a priming material (primer or liner) or coating,, in order to improve a bond between collagen-containing materials and curing poly-5 meric materials.

Collagen-containing material© are scleroprotein substances and main constituents of th© human and animal intercellular supporting substances such as cartilage tissue and bone tissue, skin and ebur dentis (dentin).. Within 10 the scope of the present invention, the coating agents are preferably used for the treatment of dentin in connnection with tooth repairs.

Especially in the dental field, curing polymeric materials are used as filling materials in tooth repairs. 15 Aerylate-based fillings are in general preferred as the curing polymeric materials- These polymeric filling© have, however, the disadvantage of poor adhesion to the dentis- For solving this problem,, undercuts! on the dentin have hitherto been made in some cases; for this 20 purpose, it was necessary to remove considerable quan~ tities of fresh dentin, beyond the attacked area.

According to another method, the dentin and the surface of the enamel are superficially etched with acids such as, for example, phosphoric acid, and the filling is then 25 carried out. Apart from the fact that the acids exert an irritant action in the buccal region,, they also easily penetrate through the dentin canals into the tooth and damage the nerve (pulpa). Moreover, bonding of the filling to the dentin is slight in this method. 30 From BF-A-14I,324, coating agents for collagen-containing materials are known, which contain an aldehyde, an olefinically unsaturated monomer having active hydrogen, optionally also as a mixture with an unsaturated monomer i having no active hydrogen, water, solvents such as - 2 - acetone or ethanol, and conventional additives (page 71, lines 24-29, page 10t, lines 1-4, and page 14, lines 20-22) . An essential subject of the invention, underlying the present Application is the simplification of the 5 procedure in adhesive filling therapy, without a loss of strength of the adhesive bond occurring,. The coating material according to the invention can, inter alia, be used on the ebur dentis (dentin) and tooth enamel. Since., in dealing with most cavities, both tooth materials have 10 to be worked, it is desirable and advantageous,, for reasons of reliable application and time-saving, to have available an application solution for both requirements. The previously disclosed adhesives are less suitable for this purpose. For applying a composite to dentin alone, 15 an additional working step as compared with the present invention is necessary according to hitherto disclosed procedure®. This additional working step comprises the preparation of an interlayer of a sealing material (EP-A 141,324, page 21, lines 10-12; "Enamel binder")- 20 It has proved to be advantageous, for example in the case of fillings of tooth cavities, first to carry out a conditioning of the fresh dentin surface. Conditioning fluids have in general a pH value from 0.1 to 3.5 and can contain an acid having a pK, value of less than 5 and, 25 optionally, an amphoteric amino compound having a pK, value in the- range from 9-0 to 10.6 and a pKs value in the range from 11.5 to 12.5.

The coating agents are intended to effect a firm bond, without leaving a gap, between the conditioned dentin 30 surface and the filling material.

A coating material for collagen-containing materials has been found, which consists of a) 1-10 % by weight of an aldehyde, - 3 - b) 10-40 % by weight of a water-soluble monomer having active hydrogen, c) 1-50 % by weight of a water-insoluble monomer having two or more polymeriaable double 5 bonds , d) 0..01-2®5 % by weight of photoinitiator, e) 15-70 % by weight of water, f) 0.2-10 % by weight of solubilizers and/or disper- sants and 10 g) 0-5 % by weight of additives known per se.

The coating agent according to the invention effects a " firm bond between the conditioned dentin surface and the filling material; in this way, the tooth repair will last for many years, 't 15 The aldehydes (a) can be aliphatic, aromatic or heterocyclic aldehydes.

In aliphatic monoaldehydes and dialdehydes, the aldehyde functional group is bound to an aliphatic, linear or branched hydrocarbon radical having I to 20, preferably 20 2 to 10 and especially preferably 2 to 6 carbon atoms. As the aliphatic radicals, methyl, ethyl, propyl, isopropvl, butyl, isobutyl, pentyl, isopentyl, hexyl, isohexyl and hydroxyethyl may be mentioned by way of example. Examples of aliphatic aldehydes are formal-25 dehyde, acetaldehyde, butyraldehyde, glutaric dialdehyde and glvoxal.

In aromatic aldehydes,, the aldehyde functional group is bound to an aromatic radical. As the aromatic radicals, aromatic hydrocarbons having S to 12 carbon atoms, 30 preferably phenyl, naphthyl and biphenyl may be mentioned. The aromatic radicals can be substituted, for example, by alkyl (C, to Cs)# alkoxy (C, to CQ)hydroxyl or carboxyl. - 4 - As examples of aromatic aldehydes may be mentioned: benzaldehyde, salicylaldehyde, vanillin and o-phthalal-dehyde.

In heterocyclic aldehydes, the aldehyde functional group 5 is bound to the heterocyclic ring™ Furfural may be mentioned as an example.

The aldehyde© for the coating agents according to the invention can be monoaldehydes or dialdehydes.-, Aliphatic monoaldehydes and dialdehydes are preferred for 10 the coating agents according to the invention.

Water-soluble monomers are to be understood as unsaturated monomers which have a water-solubility at 20eC of more than 5 % by weight, preferably 10 to 100 % by weight, relative to the mixture of monomer and water. 15 Acrylic acid and methacrylic acid and derivatives thereof, such as the acid amides and hydroxyalkyl (C, to C6) esters, are preferred.

(Meth)acrylic acid, methacrylamide, hydroxyalkyl (C, to C3) methacrylates such as hydroxyethyl methacrylate and 20 hydroxy-propyl methacrylate, as well as the ethylene, diethylene and triethylene glycol monomethacrylates may be mentioned as examples.

The water-insoluble, unsaturated monomers have a water-solubility at 20°C of less than 5 % by weight, preferably 25 0.01 to 3 % by weight. They contain two or more polymer-izable double bonds in the molecule, methacrylic and acrylic acid esters of 2-hydric to 5-hydric alcohol® having 2 to 30 carbon atoms being particularly suitable™ Alkoxy-(meth)acrylates and (meth)acrylate containing 30 urethane groups are particularly preferred.

(Meth)acrylic acid esters of the formula 0 II A- ( -O-C-OCH-j )_, , „ n X in which A denotes an n-valent, straight-chain, branched,, cyclic, aliphatic,, aromatic or mixed aliphatic/aromatic radical having 2 to 25 carbon atoms, which can also be interrupted by ~Q™ or NH bridges and can be substituted by hydroxy, oxy, carboxy, amino or halogen, X denotes H or methyl and n represents an integer from 2 to 8, preferably 2 to 4 f may be mentioned as examples™ Compounds of the following formulae may be mentioned as preferred: ho-chg-ch-chj ^ -"-CH2~CH-CH2-OR 1 OH CH3 OH CH<; m« CH2 - CH-CH2 - CH2-OS OB CH«i OS f 3 RO - CHg ■» CH • CHg - 0"—^ ^ /"~0 " CHg " ffiii-CHg " OB ^ O-co-HH-^3 "* - 6 - ch3 P-0-CH2-CH2-0-CH2k> ~oe CH«! RO-(CH9> & n »(CH2)a-QS CH3 CH3 ao-ra2-ra-CH2|o-^3|K_}^"ra2"f"CH2lr^-^T^-^<)" ch5-ch-ch?-or 1 " OH rg-ch2-ch-ch2 oh CHoi -oxj^o- ch2»ch-ch2-oe RO-CH^-CK-CHo- * I oh 0h~ch2~ch-ch2»0b oh ■CHg-CH-CH^-QR OK or i-CH2-CH-CH2-OH -CK T ri-t.«9- : o-ch2-ch-cb2-gr oh Q-CH9-CH-CH3-OR - J 2 oh I H I „ H0^sv^^2H3-003-fr(ZH3) -300-cH3«^\^\0H HCK^\^3eH %:Ks^XyW38 i h i „, | H i ho/\/\z h 3 00 HO HO E n ™ «») 13? <3> 3® I ^ BD-HD-6HD-0-&HD-i'H3-wH3~cHD-0-<:'HD-HD-tfHD'-0a ao -"< zh3)- 0-q y-0-^(®hd)-0a es,( -oa a- - L - - 8 - ro-ch2-ch2 ■ch2-ch2-or RO-CH2' H2~OI3 RO-CH; h y—ch2-or ro-c I ch3 ch„ ci *3 RO-CH- h2~os coock2-ch2-qh a c00ch2-ch2-0b in the ortho, raata or para form R0-CH9-CH^-0«C0"HHN^X^H-C0-0-CH,-CH^-0H kAcn, " " CH-s CH-> I I " e0»ch2-ch-0-c0-mh-cha-c»ch2-ch-chg»ch2-hh-c0-0-ch-ch2"0r ch- C'M ' li< u) j3 ch3 - 9 r-g-cmg-chg-o-co-n wherein R r-0-(ch2)n-0-r r-o-cchgchgoj^-r CHsc-c' " I CK-s o -ch2 o-ch "ch-> 0 II or ch2»ck-c- , n denotes a number from 1 to 4 and m denotes a number from 0 to 5. 10 In addition, the derivatives of tricyclodecane (EP-A 0,023 , 686) and reaction, products of polyols, diisocyan-ates and hydroxyalkyl methacrylates (DE-A 3,703,120, DE-A 3,703,080 and DE-A 3,703,130) should be mentioned.

A particularly preferred monomer is the so-called bis-GMA of the formula CE3 i (chg'c-coo-ch^-ch-chg- OH cb* )^C CHi 15 It is of course possible to employ mixtures of the various (meth)acrylic acid esters which can form crosslinks.. Mixtures of 20 to 70 parts by weight of bis-GMA and 30 to 80 parts by weight of triethylene glycol dimethacrylate may be mentioned by way of example. - 10 - Phot©initiators (d) are known per se (Houben-Weyl, Methoden der organischen Chemie [Methods of Organic Chemistry], volume E20, pages 80 et seg., Georg Thieme Verlag Stuttgart? 1987). Preferably, these are carbonyl 5 compoundse such as benzoin and derivatives thereof, in particular benzoin methyl ether,, benzil and benzil derivatives, for example 4,4~oxydibenzil, and other dicarbonyl compounds such as diacetyle, 2,3~pentanedion@ and The coating materials according to the invention preferably also contain co-activators which accelerate the IS polymerization reaction in the presence 'of photopolynier-ization initiators. Examples of known accelerators are aromatic amines such as p-toluidine and dimethyl-p-toluidine, tri&lkylamines such as trihexylamine, poly-amines such &s N,N,N' ,N'-tetraalkylalkylenediaraines, 20 barbituric acid and dialkylbarbituric acid.

The accelerators are in general contained in the coating material in a quantity from 0.01 to about 5 % by weight.

Alkylaminoarylsulphonamides of the formula r4 R"2 B"' wherein 25 R1 and R2 are identical or different and denote hydrogen, methyl, vinyl or phenyl, R3 denotes hydrogen, methyl and ethyl, R4 and R3 are identical or different and denote hydrogen, halogen or methyl, or R* and R3 in ortho-positions 30 can b© parts of a fused aromatic six-membered - 11 - ring, R6 and R7 are identical or different and denote hydrogen, methyl, allyl, methallyl, cyclohexyl, phenyl, benzyl, hydroxyethyl, hydroxypropyl, acryloyloxy-alkyl, methacryloyloxyalkyl, 2,3-epoxypropyl or 1,2-dihydroxyprop~l~yl (meth)aerylate, it being possible for R6 and R7 to be linked to form a morpholine or piperidine radical, may also be mentioned as co-activators.

The following may be mentioned as examples of alkylaminoarylsulphonamides : N,N~Dimethyl-p-dimethylaminobenzenesulphonic acid amide and N-hydroxyethyl-p-dimethylaminobenzenesulphonic acid amide.

The water (e) can, for example, he demineralized water.

Solubilizers within the scope of the present invention are volatile solvents (vapour pressure at 25°C more than 1000 Pa) from the group comprising the ketones, alcohols and ethers. Aliphatic ketones having 3 to 6 carbon atoms, aliphatic alcohols having 1 to 5 carbon atoms, glycol monoalkyl (Cj to C4) ethers and cyclic ethers (C« to C6) are preferred- The following may be mentioned as examples: acetone, butanone, methanol,, ethanol, propanoic isopropanol, butanol, isobutanol, sec.-butanol, tert. -butanol, ethylene glycol monomethyl ether,, tetra-hydrofuran and 1,4-dioxane.

The dispersants (£) which can be used according to the invention can be ionic and nonionic surfactants.

Examples of preferred anionic surfactants era: phosphates such a© the sodium salt of di-2-ethylhexyl phosphate, alcohol sulphates such as oleyl alcohol sulphate, alkyl (Cs to C20) benzenesulphonates and alkvl(C„ to C24)- - 12 - sulphonates t in particular the Ma salt of sulphosuceinic acid dioctyl ester.

Preferred cationic surfactants can,, for example, be: quaternary ammonium salts such as, for example, 5 methyltrioctylammonium chloride and methyltri-caprylylammonium chloride.

Honionic surfactants in the form of fatty acid derivatives .of polyols or ethylene oxide, ethoxylated fatty alcohols and phenols as well as amphoteric surfac-10 tants such as alkylaminoethanesulphonic acid can also be used according to the invention. Surface-active, high-molecular compound are particularly preferred. Water-soluble polyvinyl compounds such as polyvinyl acetate, polvmethacrylic acid and polyacrylic acid as well as 15 alkali metal salts thereof, copolymers of sodium meth-acrvlate and methacrylic acid alkyl esters may be mentioned here. Cellulose derivatives such as methyl-cellulose and carboxymethylcellulose are also vary suitable,.. Poly-N-vinyl-2-pyrrolidone is very particularly 20 suitable.

The additives known par se can be stabilizers, inhibitors, light stabilizers, dyestuffs, pigments and fluorescent substances.

Those coating agents for collagen-containing materials 25 are preferred which consist of a) 2 to 8 % by weight of an aldehyde, b) 15 to 40% by weight of a water-soluble monomer having active hydrogen, c) 2 to 40% by weight of a water-insoluble monomer 30 having two or more polymerizable double bonds, d) 0.,01 to 2.5 % by weight of photoinitiator, e) 25 to 60% by weight of water# f) 0.5 to 10% by weight of solubilizers and/or disper- sants - 13 - g) 0 to 5 % by weight of additives known per sa.

Before a collagen-containing material is coated with the coating material according to the invention,, the former is in general treated with a conditioning fluid™ The 5 composition of the conditioning fluid depends on the type of the material to be coated. For tooth enamel, 15 - 60% strength aqueous solutions of ortho-phosphoric acid are particularly suitable. As conditioning solutions for ebur dentis (dentin), it is possible to use, for example,. 10 aqueous solutions of EDTA (for example 0.5 molar,, adjusted to pH 7.4 with NaOE) or aqueous solutions which contain, 10% of citric acid and 3% of iron(III) chloride.

Conditioning fluids for a wide field of use, which can be t employed especially for tooth enamel and dentin, contain 15 acids having a pK3 value of less than 5 and optionally an amphoteric amino compound having a pK, value in the range from 9.0 to 10.»6 and a pK% value in the range front 11.5 to 12.5. The conditioning fluids can contain the following acids: phosphoric acid, nitric acid, pyruvic acid, 20 citric acid, oxalic acid, ethylenediaminetetraacetic acid, acetic acid, tartaric acid, malic acid and xnaleic acid,., Amphoteric amino compounds to be mentioned are preferably compounds of the formula H , I , R'-C-R1 ,l r3nh 25 in which R1 represents a carboxyl group, R2 denotes hydrogen or a lower alkyl radical which is optionally substituted by hydroxy, thio, methylthio, carboxy, amino, phenyl, hydroxypheny1 30 or the groups - 14 oa h2W^ xC=N- , H2N and H R3 denotes hydrogen or phenyl, it being possible for the radicals Rl and E3 to be linked by a propyl radical, or 5 in which R1 represents hydrogen,, R2 denotes the group -A-NE3X, in which A represents a bidentate alkylene radical 10 having 1 to 6 carbon atoms and I represents halogen, and R3 denotes hydrogen..

The following amphoteric amino compounds may be mentioned a® examples: glycine, serine, threonine, cysteine, 15 thyrosine, asparagine, glutamine, alanine, valine, leucine, isoleucine, proline, methionine^ phenylalanine, tryptophan, lysine, arginine, histidine, N-phenvlglycine, ethylenediamine hydrochloride, propylenediamine hydro-bromide, butylenediamine hydrochloride, butylenediaxaine 20 hydrobromide, leucine hydrochloride and histidine hydrochloride .

In addition, the conditioning fluid can also contain substances from the group of the polyethylene glycols and metal hydroxides. In particular, the abovementioned 25 polybasic acids can also be employed as . partial metal salts, as long as free acid functional groups remain.

Conditioning fluids which contain, at least one of the acids fron the group comprising pyruvic acid, ethylene-di&minetetra&cetic acid and citric acid &© well as 30 optionally an, amphoteric amino compound from the group comprising glycine, n-phenylglycine and proline, are - 15 - particularly praferred.

The coating agents according to the invention are in general prepared by mixing the components.

The formulations according to the invention can be used 5 as coating agents, preferably as priming agents (primer or liner) or coating (varnish) for improving the bonding between collagen-containing materials and curing polymeric materials.

Collagen-containing materials occur in many places in the 10 human and animal body. The use according to the invention relates of course to living and non-living materials. Teeth, bones, skin and leather may be mentioned as collagen-containing materials. The formulations according to the invention are preferably used for coating teeth in 15 preparation for tooth fillings during tooth repairs.

The curing polymeric materials are determined essentially by the field of application. Thus, for example, in the dental field,, only monomers can be used for the polymerization which are physiologically acceptable and which 20 can polymerise in the buccal region, and bis-GM& (bis-phersol A diglycidyl dimethacrylate) may be mentioned as an example.

In use, for example in a tooth repair, the conditioning fluid described is first applied, after mechanical 25 cleaning of the collagen-containing tooth material, by means of a little cottonwool and is allowed to act for 60 seconds, and the tooth material is rinsed with water and dried in an air stream,, The coating material according to the invention is then applied in a thin layer by means of 30 a small brush, and excess material is spread in an air stream. The tooth filling compound is then applied to the coating material and cured together with the latter. - 16 - Examples 1 to 5 Coating materials according to the invention Mixtures having the compositions listed below are prepared by means of a high-speed stirrer (2000 revolutions 5 per minute)- Example 1 5 g of glutaric dialdehyde 33 g of 2-hydroxyethyl methacrylate 2 g of bis-GMA vH i O g of camphorquinone (photoinitiator) 55 g of water 5 g of acetone Examol« » 2 5 g of glutaric dialdehyde 33 g of 2-hydroxyethyl methacrylate 2 g of bis-GMA 0.1 g of camphorquinone 59.2 g of -w°ater 0.7 g of polv-N-vinyl-2~pyrrolidone 20 Example 3 3.3 g of glutaric dialdehyde 23.4 g of 2-hydroxyethyl methacrylate 12.,6 g of triethylene glycol dimethacrylate 20™5 g of bis-GMA 25 57 mg of camphorquinone 167 mg of N,N-dimethylaminobenzenesulphonic acid dial- lylaatide (co-activator) 38.1 g of water 2 g of poly-N-vinyl-2-pyrrolidone - 17 ~ 33 mg of 2, 6-di-tert. -hutyl-4-methy.lphenol (stabi liser) Example 4 3.3 g of glutaric dialdehyde 23*4 g of 2-hydroxyethyl methacrylate 20.8 g of bis-GMA 12.7 g of triethylene glycol dimethacrylate 70 mg of camphorquinone 39.3 g of water 0.5 g of methyl-tricaprylammonium chloride Example 5 2.5 g of glutaric dialdehyde 18 g of 2-hydroxyethyl methacrylate 30 g of bis-GMA 17.5 g of triethylene glycol dimethacrylate 100 mg of camphorquinone 29.5 g of water 2.5 g of poly-N-vinyl~2~pyrrolidone Example 6 Application test The suitability of the coating materials of Examples 1 to 5 is tested by determining the bonding strength of a plastic material, which contains bis-GMA and triethylene glycol dimethacrylate as the monomers and camphorquinone as the photoinitiator, to dentin and enajtnel, which have been ©retreated with a conditioning fluid (60 seconds time of action, rinsing with water,, drying with air) and the coating material (60 seconds time of action,, drying with air). - 18 - Human teeth which have been extracted and stored in the moist state are used for the test. The teeth are embedded in an epoxide resin by casting. For the measurement on dentin, a smooth dentin surface is produced by wet 5 polishing. Final polishing is carried out with carbon paper 1000.

To prepare a test specimen for measuring the bonding strength, a cylindrical split Teflon mould is clamped to the dentin surface which has been treated as described 10 above {Scand. J» Dent. Res. 88# 348-351 (1980)). The photocuring plastic filling material is filled in as the filling compound™ A No. 016 round drill clamped into a hole in a drill holder is fixed to the Teflon mould and pressed from above into the layer of material which is 15 still undergoing the curing process..

The entire arrangement is left to stand undisturbed for 10 minutes at room temperature (23 ± 2°C), whereupon the drill holder and the Teflon mould are taken off and the sample is put down under water at a temperature of 20 23 + 1°C», After 21 hours,, the sample is mounted by means of the drill in an Instron tensile test apparatus (Scand. J* Dent™ Res. 88, 348-351 (1980))y a tensile strength measurement is carried out at a speed of 1 mm/minute. The tensile strength is calculated by dividing the load, 25 applied at fracture of the filling, by the cross-sectional area in the fracture surface of the test specimen. 5 measurements were carried out in each case on test specimens. The following solutions were used here as the conditioning fluids s 30 K Is 9.1 % of pyruvic acid 9.1 % of glycine 81-8 % of water s K 2: 17 % of disodium ethylenediaminetetraacetate dihydrate - 19 - 1.7 % of sodium hydroxide 81.3 % of water K 3: 35 % of ortho-phosphoric acid 65 % of water.

The results of the bonding strength measurements are summarized in the table which follows: Coating material 10 Example 1 Example 2 Example Example 3 Example 4 Example 5 Dentin Conditioning Bonding fluid strength [H/m23 x i K 1 K 2 K 2 K 2 K 2 15 ± 4 19 ± 2 12.3 ± 1 11,8 ± 4 3.3 .i 5 ± 3 14,1 ± 3 Enamel Conditioning Bonding fluid strength [N/mm2] K 1 14.8 ± 0.5 K I 16.2 1 3.7 K 3 12.6 ± 3.2 K 3 17.0 i 2.1 K 3 13.2 i 3.5 so o Example 7 (Comparison test) A coating material of the following composition was prepared: 2.5 g of glutaric dialdehyde 18 g of 2-hydroxyethyl methacrylate 30 g of bis-GMA 17.5 g of triethylene glycol dimethacrylate 100 mg of camphorquinone 7.5 g of water 24.5 g of acetone ..

The bonding strengths on dentin and enamel were determined according to the procedure described in Example 6.

Dentin Enamel Conditioning Bonding Conditioning Bonding fluid strength fluid strength [N/mm2] [N/mra2] If 0 K 3 7.2 22 -

Claims (4)

CLAIMS:

1. Coating agent for collagen-containing materialst, consisting of &) 1-10 % by weight of an aldehyde, 5 b) 10-40 % by weight of a water-soluble monomer having active hydrogen f, c) 1-50 % by weight of a water-insoluble monomer having two or more polymerizable doubl© bonds, 10 d) 0.01-2.5 % by weight of photoinitiator, e) 15-701 by weight of water, f) 0.2-10 % by weight of solubilisers and/or dispersants and .g) 0-5 % by weight of additives known per 15 •' se«

2. Coating agent according to Claim 1„ consisting of a) 2 to 8 % by weight of an aldehyde, b) 15 to ■ 40% by weight of a water-soluble monomer having active hydrogen, 20 c) 2 to 40% by weight of a water-insoluble monomer having two or more polymerizable double bonds d) 0.01 to 2.5 % by weight of photoinitiator, e) 25 to 60 % by weight of water, 25 f) 0.5 to 10 % by weight of solubilisers and/or dispersants and g) 0 to 5 % by weight of additives known per S3.

3. Coating material according to Claims 1 to 2, 30 characterized in that a dispersant is used as the component £) .

4. Coating material according to Claims 1 to 3, characterized in that poly-N-vinyl-2-pyrrolidone is used as the dispersant. Process for preparing coating material for collagen-containing material, characterised in that a) 1-10 % by weight of an aldehyde, b) 10-40 % by weight of & water-soluble monomer having active hydrogen, c) 1-50 % by weight of a water-insoluble moaomer having two or more polymeris&bie double bonds, d) 0.01-2.5 % by weight of photoinitiator, e) 15-70 % by weight of water, £) 0.2-10% by weight of solubilizers and/or dispersants and optionally g) 0-5 % by weight of additives known per S8| are nixed with stirring,, A coating agent according to Claim 1, substantially as hereinbefore described and exemplified. A process for preparing a coating material according to Claim 1, substantially as hereinbefore described. A coating material according to Claim 1, whenever prepared by a process claimed in a preceding claim. F. r. KELLY & CO., AGENTS FOR THE APPLICANTS.