CA1161878A - Process for the production of documents which cannot be falsified - Google Patents

Abstract

PROCESS FOR THE PRODUCTION OF DOCUMENTS WHICH CANNOT BE
FALSIFIED

Abstract of the Disclosure The process relates to the production of tamperproof documents by laminating an information carrier on one or both sides with foils which have an adhesive layer which is hardened by radical cross-linking.

Description

7 ~
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Process _or the production of documents which cannot be falsified.
_ This invention relates to a process for the pro-duction of tamperproof documents by laminatin~ an infor-mation carrier with plastics foil on one or both sides.
Documents which are tamperproof or cannot be falsified are becoming of increasing importance. They are used, for example, in the form of credit cards by banks, retail stores, oil companies, airlines and industrial finance companies to facilitate cash-free transactions. Such documents contain information re-ferring both to the owner of the document and to the authority issuring the document and in the interests of both parties they are required to be proof against falsification. There have therefore been many attempts to make such information carriers tamperproof.
It is known, for exam~le, to Produce a laminate in which a card carryin~ nrinted information ;s inserted between tw~ foilds. Each laminating foil is treated in certain areas so that in these areas it will not adhere to the paper surface of the car~. If anv attem~t is made to stri~ the laminatinq foil from the card. the tear will, on reachinq the Previously ~re~ared areas, follow the line of least resistance and therefore shift to the paper surface so that the paper tears (German Offenlegungsschrift No. 2,511,367).
According to another proposal, a printed informa-tion carrier in the form of a so-called "composited inlet" consisting o~ a paper card with a foil edging is sealed in between two transparent foils. The foil edging enables the edges of the paper card to be !~

'7 ~

sealed in, thereby making it more difficult to split open the welded card (German Offenlegun~sschrift No. 2,756,691).
One disadvantage of the known laminating processes is that when the foils used for this purpose are sealed to the paper, they are only incompletely bonded to the paper surface of the information carrier and therefore provide only limited protection against falsification.
The seal round the edges only provideds an insignificant improvement under these conditions since it can easily be removed and renewed. Another disadvantage of the known laminating processes is that the foil attached to the paper can be removed by heating or by chem cal means.
It is an object of the present invention to enclose an information carrier such as, for example, a credit card or an identification card, ln a transparent foil in such a manner that the whole surface of the informa-tion carrier is not accessible without destruction o the carrier and cannot therefore be tampered with.
The problem according to the invention is solved by a process for the production of tamperproof docuements by laminating an ln~ormation carrier on one or ~oth sides with foils, at least one of which is transparent, and the process is characterisecl in that the foil has an adhesive layer consisting o~ a mass which is haredened by radical cross-linking, and the foil is laminated to one or both sides of the information carrier in such a manner that the adhesive layer is brouaht into contact with the information carrier, and the laminate is hardened.

~ ~ 61~J8 Hardening of the adhesive layer of the laminate is effected by means of high energy radiation, initiators which can be activated by UV light or initiators activated by heat or by accelerators.
The adhesive layer used according to the invention contains, as substances which can be hardened by radi-cal cross-linking, ethylenically unsaturated, monomeric, oligomeric or polymeric compounds, mainly ~,B-unsaturated compounds or compounds containing vinyl groups, and in particular compounds containing acrylate and/or methacrylate groups.
Where acrylic compounds are referred to in the following text, this should be understood to include methacrylic compounds.
According to a preferred embodiment, ethylenically unsaturated oligomeric or polymeric compounds capable of ~eing hardened by radical cross-linking are used, in particular those based on polyesters, d, B-unsaturated polyesters, polyethers, polyepoxides, polyurethanes, urethane modiied polyepoxides, urethane modified poly-ester, urethane modified polyethers and unsaturated polymers.
The following are mentioned as examples of compounds capable of radical cross-linking which are particularly suitable or the process of the invention:

I Reaction products o polyisocyanates with hydroxy-alkyl acrylates and optionally with polyols which may contain from 0.01 to 10 ~ by weight, based on the reaction product, preferably rom 0.1 to 5 ~
by weight of organically bound sulphur in the form of thio and/or dithio groups.

The reaction products preferably consist of:
A) 1 gram equivalent of isocyanate of a polyisocyanate having at least two, e.g. from 2 to 4 in particu-lar 2 isocyanate groups per molecule, B) from 0 to 0.7 gram equivalents of hydroxyl of a polyol having at least 2, in particular from 2 to 6 hydroxyl groups per molecule (suitable polyols have been described in German Offenlegungsschrift No. 2,737,406), C) from 0.01 to 1.0 gram equivalent of hydro~yl of a hydroxy alkyl acrylate having at least 2, in par-ticular from 2 to 4 carbon atoms in the alkyl group and D) optionally from 0.01 to 0.3 gram equivalents of hydroxyl of a polyol containing thio or dithio groups or thio and dithio groups and having at least 2, in particular ~rom 2 to 4 hydroxyl groups per molecule;
wherein the sum of hydroxyl gram equivalen-ts B to D is from 1 to 1.2 and tne quan~ity o~ organically bound sulphur from the thio and dithio groups may be from 0 to 10 % by weiaht, in particular from 0.1 to 5 %.b~
weight, basea on the reaction product.
The reaction products and their preparation have been described in detail in German Auslegeschrift.No.
1,644,797; British Patent No. 743,514; US Patent No.
3,297,745 and German Offenlegungsschrift.No. 2,.73?,406.
The reaction products may be used in.admixture with mono~unctional and/or polyfunctional.vinyl monomers;
information on this possibility is given in German Offenlegungsschrift No. 2,737,406.

`~ il 6~7~

II. ~eaction products of polyepoxides having more than one epoxide grouP (e.g. 2.3 epoxypropyl groups) per molecule, preferably from 2 to 6, in particular from 2 to 3 epoxide groups, with acrylic or methacrylic acid.

The preparation is carried out by known methods of reacting the polyepoxide with (meth)acrylic acid or mixtures thereof, for example at 40 to 100C, optionally in the presence of about 0.01 to 3 %
by weight, based on the quantity of epoxide plus acid, o catalysts which accelerate the reaction, such as tertiary amines, alkaline metal hydroxides or alkali metal salts of organic carboxylic acids (see US Patents Nos. 2,456,408; 2,575,440 and

2,698,308).

A detailed description of these reaction products is given in German Ofenlegungsschrift No. 2,349,979.

III. Urethanised reaction products of polyepoxides have been described, e.g. in German Offenlegungsschrift No. 2,164,386. ~xamples of such compounds include urethane resins containing vinyl and optionally carboxyl groups obtained from polyepoxides having more than one 1 r 2-epoxide group per molecule, B-monoolefinically unsaturated carbo~ylic acids, isocyanates and optionally cyclic dicarboxylic acid anhydrides.

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The urethane resins are obtained by first reacting the polyepoxide with acrylic and/or methacrylic acid so that from 60 to 100 % of the 1,2-epoxide groups present are converted into ~-hydroxyacrylic or B-hydroxymethacrylic acid ester groups and then reacting the correspondinq hydroxyl qrou~s with an isocYanate so that from 30 to 90 ~ of the hydroxyl groups present in the B-hydroxyacrylic or B-hydroxymethacrylic acid esters are converted into the corresponding urethanes, and then optionally reacting the hydroxyl groups still present with a cyclic dicarboxylic acid anhydride.
The compounds and their preparation have been described in detail in German Offenlegungsschrift No. 2,557,408.
Further examples of urethanised reaction products of polyepoxides include those of 1,2-polyepoxides and olefinically unsaturated carboxylic acids consisting of A) an epoxyacrylate optained by reaction t1) o a diglycidyl ester of a hydroxyphthalic acid or (2) of a polyglycidyl ether of polyvalent phenols, in particular bisphenol A, with acrylic or methacry-lic acid or mixtures thereo~ such that from 90 to 100 ~ of the 1,2-epoxide g:roups are esterified with methacrylic acid or acrylic acid, and B) hexamethylene diisocyanate, cyclohexane-1,4-diiso-cyanate, tolylene-2,g- and 2l6-diisocyanate and mixtures thereof, isophorone diisocyanate (1-iso-cyanatomethyl-5-isocyanato-1,3,3-trimethyl-cyclo-hexane), phorone diisocyanate (2,2,4- and 2r4~4~
trimethyl-hexamethylene diisocyanate-1,6), 1,5-naphthalene diisocyanate, 1,3-cyclopentylene 6 ~
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diisocyanate, m- and p-phenilene diisocyanate, 2,4,6-tolylene triisocyanate, 4,4',4"-triphenyl-methane triisocyanate, 1~3- and 1,4-xylylene diiso-cyanate, 3,3'-dimethyl-4,4'-diphenylmethane diiso-cyanate, 4,4'-diphenyl-methane-diisocyanate, 3,3'-dimethyl-bisphenylene-diisocyanate, 4,4'-bispheny-lene-diisocyanate, durene diisocyanate, 1-phenoxy-2,4'-phenylenediisocyanate, 1-tert.-butyl-2,4-phenylene diisocyanate, methylene-bis-4,4'-cyclo-hexyl-diisocyanate, 1-chloro-2,4-phenylenediiso-cyanate or 4,4'-diphenylether diisocyanate, 2 gram equivalents of reaction product A being reacted with from 0.1 to 0.9 mol, pre~erably from 0.5 to 0.9 mol of isocyanate~

The reaction products and their preparation have beeen described in detail :Ln German O~fenlegungs-schriften Nos. 2,841,880; 2,164,386 and 2,557,408.

TV. Reaction Droducts o a polyepoxide havina ~P
than one epoxide group per molecule, in which at least 60 % of the epoxide groups have been reacted A) with from 0.01 to 0.6 thio equivalents, based on 1 epoxide equivalent, of hydro~en sulphide, an aliphatic or cycloaliphatic, aromatic or arali-phatic dithiol or polythiol, or a mixture of the aforesaid sulphur compounds, and subsequently b) with from 0.99 to 0.4 carboxyl equivalents, based on 1 epoxide equivalent, of acrylic or methacrylic acid or a mixture of acrylic and methacrylic acid.

i78 By "polyepoxides" are understood in the present context compounds which contain more than one epoxide group (e.g. 2.3 epoxypropyl yroups) per molecule, pre-ferably from 1.6 to 6, in particular from 1.6 to 3 epoxide groups. Epoxide equivalent also indicates the quantity in grams of an epoxide compound containing one epoxide group.
The reaction products and the method of preparing them have been fully described in German Offenlegungs-schrift No. 2,533,125.

V. Reaction products of a polyepoxide having more than one epoxide group per molecule in which at least 60 % of the epoxide groups have been reacted A) with from 0.01 to 0.5 amino equivalents, based on 1 epoxide equivalent, of ammonia or of an aliphatic or cycloaliphatic primary or secondary amine or of a mixture of the above mentioned nitrogen compounds, and thereafter B) with from 0.99 to 0.5 carboxyl equivalents, based on 1 epoxide equivalent, of acrylic or methacrylic acid or of a mixture of acrylic acid methacrylic acid.

By "polyepoxides" are meant in this context com-pounds containing more than one eqoxide group (e.g.
2.3 epoxpropyl groups) per molecule, preferably from 1.6 to 6, in particular from 1.6 to 3 epoxide groups.
One epo~ide equivalent is the quantity of an epoxide in grams containing one epoxide group.

1 lB~878 g P~ detailed description of the reaction products and their preparation may be found in German Offenle-gungsschrift No. 2,429,527.
The modified polyepoxides described under IV and V
may also be urethanised as described under III.

VI. Polyesters and polyethers esterified with ethyleni-cally unsaturated groups.
Examples include esterification products of hydroxyl polyesters or hydroxypolyethers with acrylic and/or methacrylic acid.
Suitable polyesters and polyethers containing hydroxyl groups have been described in German Offenle-gungsschrift No. 2,60~,g98.
Examples of polyesters esterified with ethy-lenically unsaturated groups are given in German Offen-legungsschri~t No. 2,838,691.

VII. O~B-Unsaturated polyester resins are also suitable.
~B Ethylenically unsaturated polyesters include, for the purpose of this invention, t:he usual polycondensation products o~ at least one C~B-ethylenically unsaturated dicarboxylic acid generally having 4 to 5 carbon atoms or ester forming derivatives thereof, which may be mixed with up to 90 mol ~ ased on the unsaturated acid components, o~ a~ ieast one aliphatic saturated dicarboxylic acid having from 4 ta 10 carbon atoms or at least one cycloaliphatic dicarboxylic acid having from 8 to 10 carbon atoms or ester ~orming derivatives thereo with at least one polyhydroxyl compound, in particular a dihydroxyl compound having from 2 to 8 7 ~

carbon atoms, in other words polyesters such as those described ~y J. Bjorksten et al in "Polyesters and their Applications", Reinhold Publishing Corp., New York 1956.
Examples of preferred unsaturated dicarboxylic acids or their derivatives include maleic acid, maleic acid anhydride and fumaric acid. Mesaconic acid, citra~
conic acid, itaconic acid and chloromaleic acid, for example, may also be used. Examples of aliphatic saturated and cycloaliphatic dicarboxylic acids and their derivatives which may be used include phthalic acid, phthalic acid anhydride, isophthalic acid, terephthalic acid, hexahydric and tetrahydric phthalic acid and anhydrides thereof, endomethylene tetrahydro-phthalic ac~d and its anhydride, succinic acid, succinic acid anhydride and succinic acid esters and chlorides, adipic acid and sebacic acid.
The dihydric alcohols used may be ethylene glycol, propane-1,2-diol, propane-1,3-diol, diethylene glycol, dipropylene glycol, butane-1,3-diol, butane-1,4-diol, neopentyglycol, hexane-1,6-diol, 2,2-bis-(4-hydroxy-cyclohexyl)-propane, bis-hydroxyalkylated bisphenol A, perhydrobisphe~ol and others. ~thylene ~lycol, propane-1,2-diol, diethylene glycol and dipropylene glycol are preferably used.
Further modifications may be obtained by the incorporation of up to 1~ mol %, based on the alcohol or acid components, of monahydric, trihydric acid tetrahydric alcohols having from 1 to 6 carbon atoms, such as methanol, ethanol, butanol, all~l alcohol, benzyl alcohol, cyclohexanol and tetrahydrofurfuryl alcohol, trimethylolpropane, glycerol and pentaerythri-8 ~ ~

tol as well as mono-, di- and triallylethers and benzyl ethers of trihydric acid higher hydric alcohols having from 3 to 6 carbon atoms according to German Auslegeschrift No. 1,024,654, as well as by the incorporation of monobasic acids such as benzoic acid or long chain unsatuated fatty acids such as oleic acid, linoleic fatty acid and ricinene fatty acid.
The acid numbers of the polyesters should be from 1 to 100~ preferably from 20 to 70, the hydroxyl numb~rs from 10 to 150, preferably from 20 to 100 r and the molecular weights Mn determined as numerical averages shouId be within the range of about.50Q to 5000, preferably about 1000 to 3000 (de~ermined by vapour pressure osmometry in dioxane and actone; if different values are obtained, the lower is regarded as the correct value).
The unsaturated polyesters and their preparation have been described in detail, for example in German Auslegeschriften Nos. 1,024,654; 1,054,620 and 2,221,335.

VIII. Masses which have been prepared by the poly-merisation of suitably substituted ethylenically un-saturated, preferably vinylically unsaturated and in particular arylically and/or methacrylically unsaturated compounds in such a manner that the resuIting polymers can subsequently be reacted on their substituen.ts with ethylenic, pre~era~ly vinylic and in particular acrylic and/or methacrylic derivatives are also suitable. The unsaturated copol~ers obtained and methods of pre-paring them have been described in detail, for example in German Offenlegungsschrift No. 1,964,547.

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The compounds mentioned under VI. and.VIII. rnay, if they ha~e the necessary hydroxyl number, be urethanised as under III. if desired.
Mixtures of the compounds mentioned under I. to VIII. may, of course, also be used.
The adhesive layer used according to the invention may also consist of monomers capable of being hardened by radical cross-linking, in particular those having a sufficiently high boiling point, of about 100C or higher.
The hardenable masses used for the adhesive layer may be monomers capable of.radical cross-linking mixed with the oligomers or polymers mentioned above and/or with thermoplasts not capable of radical cross-linking, which are used as film formers.
The ~ollowing are examples o~ suitable monomers ~or this purpose:
1) Esters of acrylic or methacrylic acid and aliphatic C1-C8, cycloaliphatic C5-~6 or araliphatic C7-C8 monohydric alcohols; for example, methyl acrylate, ethyl acrylate, n-propyl a.crylate, n-~utyl acry-late, methyl hexyl acrylate, 2-eth~lacrylate and the corresponding methacrylic acid esters; cyclo-pentylacrylate, cyclohexyl acrylate and the corresponding methacrylic acid esters; benzyl acrylate, ~-phenylethylacrYlate and the corres-ponding methacrylic acid esters;
2) Hydroxyalkyl esters o~ acrylic or methacrylic acid having ~rom 2 to ~ carbon atoms in the alcohol compone~ts, such as hydroxyethylacrylate, 2-hydroxy-propylacrylate, 3-hydroxypropylacr~late, 2-hydroxy-.. .. ... . . . . .

butylacrylate, 4-hydroxybutylacrylate and the corresponding methacry.lic acid esters;

3) Di- and polyacrylates and di- and po'ymethacrylates of diols and polyols having 3 or 4 hydroxyl groups ~hich may be alkoxylated, preferably ethoxylated or propoxylated, such as ethylene glycol diacrylate, propane diol-1,3-diacrylate, butanediol-1,4-diacrylate, hexanediol-1,6-diacrylate, trimethylol-propane triacrylate, pentaerythritol triacrylate and tetracrylate and the corresponding methacrylate;
also di(meth)acrylates of polyether glycols o~
glycol, propanediol-(1,3) and butanediol-(1,4~;

4) aromatic vinyl and divinyl compounds such as styrene, methylstyrene and divinylstyrene;

5) N-methylolacrylamide and N-methylolmethacrylamide and the corresponding N-methylolalkylethers having from 1 to 4 carbon atoms in the alkylether group and corresponding N-methylolallylethers, in parti-cular N-methoxymethyl(meth)acrylamide, N-butoxy-methyl(meth)acrylamide and N-allyloxymethyl(meth) acrylamide;

6) vinyl alkyl ethers havin~ ~rom 1 to 4 carbon atoms ~n the alkyl group, such as.vinyl methyl ether, vinyl ethyl ether, vinyl propyl ether and vinyl butyl ether;

7) trimethylolp~opane diallylether mono(meth)acrylate, vinyl pyridine, N-vinyl carbazole, triallylphosphate, triallylisocyanurate, N~vinylpyrrolidone, etc.

8 ~ 8 Mixtures of one or more of the above mentioned monomers may also be used.
Mi~tures of the a~ove mentioned monomers with oligomers or polymers or film forming thermoplasts, can be influenced in their properties by the proportions of the indivi.dual components. Liquid mixtures contain a relatively high proportion of monomers. If the mixtures to be hardened by radical cross-linking are required to be highly viscous, gel-like or solid su~stances, the proportion of monomers will be reduced accordingly.
The following are examples of suitahle film for-mers:

1. Copolyesters prepared ~rom the reaction.product o~
a polymethylene glycol having the formula HO(CH2)nOH, in which the value of n is ~rom 2 to 10, and ~1) hexa-hydroterephthalic acid, sebacic acid and terephthalic acid, (2) terephthalic acid, isophthalic acid and sebacic acid, (3) terephthalic acid and sebacic acid, (4) terephthalic acid and isophthalic acid and (5) mixtures of the copolyesters prepared from the above mentioned glycols and (i) terephthalic acid, iso-phthalic acid and sebacic acid and (ii) terephthalic acid, isophthalic acid, sebacic acid and adipic acid;
2. Polyamides.such as, for example, N-methoxymethyl polyhexamethylene-adipic acid amide;
3. Vinylidene chloride copolymers, e.g. copolymers of vinylidene chloride and acrylonitrile, of vinylidene chloride and methyl acrylate and of vinylidene chloride and vinyl acetate;
4. Ethylene/vinyl acetate copolymers;
S. Cellulose ethers, e.~. methyl cellulose, ethyl cellulose and ~enzyl cellulose;

~ i~ 3 7 8 6. Polyethylene;
7. Synthetic rubbers, e.g. butadiene/acrylonitrile copolymers and chloro-2-butadiene-1,3 copolymers;
8. Cellulose esters, e.g. cellulose acetate, cellulose acetate succinate and celluIose acetobutyrate;

9. Polyvinyl esters, e.g. polyvinyl acetate-acrylate, polyvinyl acetate-methacrylate and poly~inyl acetate;

10. Polyacrylate and -alkylpolyacrylate esters, e.g.
polymethacrylate and polyethy-lmethacrylate;

11. High molecular wei~ht polyethylene oxides and polyglycols having an avera~e molecular weight of approximately 4000 to 1,000,000;

12. Polyvinyl chloride and.vinyl chloride copolymers, e.g. polyvinyl chloride acetate;

13. Polyvinyl acetals, e.g. polyvinyl butyrate and polyvinyl formal;

14. Polyformaldehydes;

15. Polyurethanes;

16. Polycarbonates; and

17. Polystyrenes.

Suitable mixtures have been describe~, for example, in US Patents Nos. 2,760,863; 3,06Q,026; 3,261,686 and 3,380,831.
The adhesive layer accord:Lng to the invention may be cross-Linked by means of high energy radiation such as U~ light, electron rays or gamma rays. When W -light is used, the layer is exposed to this light in the presence o photo-initiatos.

The photoinitiators may be the usual compounds used for this purpose such as, for example, benzophenone and aromatic ketone compounds derived from ben~ophenone in general, such as alkylbenzophenones, halogen methylated benzophenones according to German Offenle-gungsschrift No. 1,949,010, Michlers ketone, anthrone and halogenated benzophenones. Benzoin and its deri-vatives are also suitable, for example those described in German Offenlegungsschriften Nos. 1,769,168;
1,769,853; 1,769,854; 1,807,297; 1,807,3Q1 and 1,919,678 and German Auslegeschrift No. 1,694,149.
Anthraquinone and numerous of its derivatives are also effective photoinitiatos; for example, B-methyl-anthraquinone, tert.-butyl anthraquinone and anthra-quinone carboxylic acid esters; oxime esters according to German Offenlegungsschrift ~o. 1,795,089 and phenyl glyoxylic acid esters according to German Offenlegungs-schrift No. 2,825,955 are also sultable.
Benzyl dimethylketal, benzoin isopropylether and the benzophenone/amine system as described in US Patent No. 3,759,807 are particularly suitable photoinitiators.
The most suitable photoinitiators for any given system which is to be photo cross-lin~ed can be determine~ by a few simple laboratory rests.
The adhesive layer according to the invention may also be cross-linked by the addition of polymerisation initiators which when activated by heat or accelerators release a radical polymerisation, i.e. polymerisation effected by so-called external radical formers. Common-ly used polymerisation initiators have been described 8 7 ~

for example in Wagner/Sax. Lackkunstharze, in the chapter entitled "Ungesattigte Polyesterharze", 5th Edition, publishexs Carl Hauser Verlag, ~tuttgart 1971; Ullmanns Ezyklopadie der technischen Chemie, Volume 13, 3rd Edition; Houben-Weyl, "Methoden der organischen Chemie", pu~lishers Georg Thieme Verlag, Stuttgart 1961, ~olume 14~1, pages 215 et weq and 229 et seq; and Brandrup/Immergut, Polymer Handbook, John Wiley & Sons, Ne~ Yor~, 2nd Edition 1975.
The following are examples of conventional poly-merisation initiators: Acyl peroxides such as diacetyl peroxide, dibenzoyl peroxide, di-p-dichlorobenzoyl peroxide and benzoyl peroxide; peroxidic esters such as tert.-butyl peroxyacetate, tert.-butyl peroxybenzoate, ter-t.-butyl peroctoate, dicyclohexyl peroxycarbonate and 2,5-dimethylhexane-2,5-diperoctoate; alkyl peroxides such as bis-(ter.-butyl peroxybutane), dicumyl per-oxide, tert.-butyl cumyl peroxide, tert~-butyl per-oxida, and lauroyl peroxide; hydroperoxides such as cumene hydroperoxide, tert.-butyl hydroperoxide, cyclo-hexanone hydroperoxide, methyl ethyl ketone hydro-peroxide and methyl isobutyl ]~etone hydroperoxide, perketals such as 1,1-ditert.-butyl peroxy-3,3,5-trimethylcyclohexane; ketone peroxides such as cyclohexanone peroxide and ethyl methyl ketone peroxide, azo compounds such as azoisobutyrodinitrile, and acetyl acetone peroxide.
Non-peroxidic polymerisation initiators of the C-C-splitting type t~,~,~ '-tetrasubstituted ethanes~ such as those described in German Auslege-schriften Nos. 1,216,877 and 1,219,224 and Germn 7 ~

- 18 -Offenlegungsschriften Nos. 2,615,039; 2,164,482;
2,625,027; 2r131,623; 2,656,782; 2,632,294; 2,853,938 and 2,9~9,951 and in Kunststoffe 68 t1978) page 593 et seq and Kunststoffe 66 (1~6) page 688 et seq are also suitable.
The following are specific examples: Acetophenone pinacol; benzopinacol, 3,4-diphenyl-3,4-dimethylhexane;
1,2-dichloro-tetraphenylethane, tetraphenylsuccinic acid dinitrile, 1,2-dicyano-1,2-diphenylsuccinic acid dinitrile; 1,2-dicyano-1,2-diphenylsuccinic acid ester;
benzopinacol silylether and benzopinacol alkylether.
The radical polymerisation initiators may be used each on itw own or as mixtures.
Benzopinacol silylether described in German Offen-legungsschrift No. 2,632,294 is particularly preferred.
The qualitatively and quantitatively most suitable polymerisation initia-tors or mixtures thereo~ for any given cross-linking system may be determined by a few simple laboratory tests.
If, for example, it is de~3ired to obtain adhesive layers with a high stability iII storage, it ls preferred to use polymerisation initiators which have a suffi-cien~ly high starting temperature. If, on the other hand, cross-linking is to be carried out at relatively low or am~ient temperature, polymerisation initiators with a lower starting temperature are preferred.
By starting temperature is meant che temperature to which the adhesive compound according to the inven-tion containing polymerisation initiator must be heated to release controlled decomposition o~ the

- 19 -polymerisation initiator for the purpose o~ cross-linking the adhesive compound.
It may be advantageous to add certain accelerators to increase the reactivity, such as, for example, cobalt or vanadium naphthenates or octoates, tertiary amines, amides, amidines, sulphinic acid, mercaptans or aryl-phosphinic acid esters. Accelerators such as these have been described, for example, in Wagner/Sarx, Lackkunstharze, 5th Edition, publishers Carl Hanser Verlag, Munich 1971, Chapter entitled "Ungesattigte Polyesterharze", and in German Offenlegungsschrift No.
2,6S0,173.
It may be advantageous, in order to prevent pre-mature activity of the polymerisation initiators, possibly in conjunction with accelerators, to add the polymerisation initiator and/or the accelerator t~e the adhesive compounds according to the invention in a microcapsular form.
The polymerisable compouncls according to the invention which are to be hardened by radical cross-linking may be protected against premature polymerisa-tion by adding to them, at the stage of their preparation, from Q.0a1 to 0.1 % by weight, based on the whole mixture, of polymerisation inh1bitors or antioxidants.
Suitable additives of this type include, for example, phenals and phenol derivatives, particularly sterically hindered phenols which have alkyl sub-stituents with 1 to 6 carbon atoms in both ortho-positions to the phenolic hydroxyl group, amines, preferably secondary arylamines a~d their derivatives, ~g~7~

- 20 quinones, copper-(I) salts of organic acids or products of addition of copper-(I) halides to phosphites.
The following are specific examples: 4,4'-Bis-(2,6-di-tert.-butyl-phenol); 1, 3 t5-trimethyl-2 r4 ~ 6-tris-(3~5-di-tert.-butyl-4-hydroxybenzyl)-benzene; 4 ~4 '-butylidene-bis-(6-tert.-butyl-m-cresol~; 3,5-di-tert.-butyl-4-hydroxy-benzyl-phosphonic acid diethylester; N,N'-bis-(B-naphthyl)-p-phenylenediamine; N,N'-bis~ methyl-heptyl)-p-phenylene diamine; phenyl-B-naphthylamine;
4,4'-bis-( , -dimethyl-benzyl~-diphenylamine; 1,3,5-tris-(3,5-di-tert.-butyl-4-hydroxyhydrocinnamoyl)-hexyhydro-s-triazine; hydroquinone; p-benzoquinone;
2,5-di-tert.-hutylquinone; toluhydroquinone; p-tert.-butyl pyrocatechol; 3-methylpyrocatechol; 4-ethyl-pyrocatechol; chloranil; naphthaquinone; copper naphthenate; coppex octoate; Cu(I)Cl/triphenylphosphite;
Cu(I)Cl/trimethylphosphite; Cu(I)Cl/tris-chloroethyl-phosphite; Cu(I)Cl/tripropylphosphite and p-nitroso-dimethylaniline.
Other suitable stabilizers have been described in "Methoden der organische.n Chemie" (Houben-Weyl), 4th Edition, Volume XIV/1, pages 433-452 and 756.
publishers Georg Thieme Verla~, Stuttgart, 1961.
Particularly suitable stabilizers, for example, are p-benzoquinone and/or hydroquinone monomethyl ether used at a concentration of from 0.001 to 0.05 % by weight, ~ased on the whole mixture.
Suitable materials for the foils include e.g.
polyolefines such as polyethylene, cellulose esters, polyvinyl acetate, polypropylene, polystyrene, poly-

- 21 -vinyl chloride, polyvinylidene chîoride, polyvinyl fluoride, polytetrahalogen ethylene and polycarbonates, in particuIar those based on bisphenol A, and poly-es~ers, in particuIar those based on polyethylene terephthalate and polybutylene terephthalate, and poly-amides, e.g. polyamide-6 or polyamide-66.
So-called composite foil consistin~ of single foils of the same or di~fering chemical composition may, of course, also be used. The following are examples:
Polyethylene/polyamides, polypropylene/polyamides and polyolefine foils used to~ether with other foil materials such as polyesters, e.g. polyethylene terephthalate.
Suitable foils and composite foils have been described in Ullmanns Encyklop~die der technischen Chemie, ~th Edition, Volume 11, pages 673 et seq.
The thickness of the foils used according to the invention depends on the desired stifness of the laminate. Total thicknesses of from 10 to 259 /u are generally sufficient.
The surface of the foil to which the compound which is to be hardened by radical cross-linking is applied may be pretreat~d be~ore being coated with this compound in order to improve the bond between the foil and the compound. This pretreatment ensures uni~orm application of~the compound and increases i~s adherence. In the case oE polyolefines, Eor example, suitable results are obtained by means o~ the usual corona treatment.
The adherence of the compound which is to be

- 22 -cross-linked to its supporting foil may, of course, also be strengthened by other measures, e.g. b~
application of a suitable substrate layer.
Application of the compound hardened by radical cross-lin~ing to the foil may be carried out by the usual methods employed in the lacquer industry, such as spraying, application with rollers or doctor wipers, printing, immersion, centrifuging, flooding, spread coating, brush coating, etc.
The thickne~s of the adhesive layer, when dry, depends on the particuIar requirements and the adhesive power of the compound which is to be hardQned.
Thicknesses of from 2 to 50 /u would generally be sufficient.
The information caxrier used for the process according to the invention would generally be made of paper, which may be printed, embossed or written upon or provided with the required information by some other means. The information carrier may also consist of photographic paper or film containing black-and-white or colour photographic records, pictures and/or symbols and/or other information or other identification features. The support layer of such photo~raphic information carriers may consist of the usual materials used in commercial or art photography. The followin~
are examples: Paper, paper treated with reflection layers, polyolefine laminated paper and the usual film supports made e.g. of cellulose triacetate or poly-esters, which may be in the form of opaque, pigmented support layers. The photographic emulsion layers Qr 1 ~6~87~

- 23 -au~iliary layers of such information carriers have the usual compositions o~ photographic materials.
The surface of the foil to which the compound which is to be hardened by radical cross-linking is applied may be pretreated before being coated with this compound in order to improve the bond between the foil and the compound. This pretreatment ensures uniform application of the compound and increases its adherence. In the case of polyolefines, for example, suitable results are obtained by means of the usual corona treatment.
The a & erence of the compound which is to be cross-linked to its supporting foil may, of course, also be strengthened by other measures, e.g. by appli-cation o~ a suitable substrate layer.
Application of the compound hardened by radical cross-linking to the foil may be carried out by the usual methods employed in the lacquer industry, such as sprayin~, application with rollers or doctor wipers, printing, immersion, centri~uging, flooding, spread coating, brush coating, etc.
The thickness of the adh~sive layer, when dry, depends on the particular xe~uirements and the adhesive power of the compound which is to be hardened. Thick-nesses of from 2 to 50 /u would generally be sufficient.
The information carrier used for the process according to the invention would generally be made of paper, which may be printed, embossed or written upon or provided with the re~uired information by some other means. The information carrier may also consist a 7 s

- 24 -of photographic paper or film containing black-and-white or colour photographic records, pictures and/or symbols and/or other information or other identific~tion features. The support layer of such photographic infor-mation carries may consist of the usual materials used in commercial or art photography. The following are examples: Paper, paper treated with reflection layer, polyolefine laminated paper and the usual film supports made e.g. of celluIose triacetate or polyesters, which may be in the form of opaque, pigmented support layersO
The photographic emulsion layers or auxiliary layers of such information carriers have the usual compositions of photographic materials.
To laminate the foil carrying the compound which is to be hardened by radical cross-linking to the surface of the information carrier, the foil is heated to a temperature of upt o 200C, preferably up to 120C
and most preferably to a temperat:ure in the region of from 50C to 120C. The foil is pressed against the surface of information carrier to form a laminate which is free from bubbles and creases. Any pressure beyond that required to achieve this effect is generally not necess2ry.
Lamination is preferably carried out continuously by bringin~ the individual information carriers successive-ly to the foil which is supplied from a roll. A laminate is thus obtained in the form of a band from which the parts containin~ the informatlon may subsequently be punched out, and the welded foil can be removed at a distance of about 1 to 2 mm from the edge of the infor-~5 -mation carrier, depending on the thickness of the information carrier. This thickness is generally from 50 to 250 /u. The information carrier obtained is thus completely enveloped on all sides so that there is no need subsequently to weld the edges.
Discontinuous lamination, using separate sheets of foil, will , of course, produce the same results.
Hardening may be carried out at various stages, depending on the nature and reactivity of the compound which is to be hardened by radical cross-linking, but it is generally carried out after lamination. In some individual cases, it may be advantageous to effect cross-linking before lamination.
The conditions required for hardening the adhesive layers according to the invention depend on the reactivi-ty of the compound which is to be hardened, the poly-merisation initiators employed and any accelerators used, if any.
If the laminate to be hardened is to be irradiated, it is suitable to use the usual sources of light for reproduction work, which have an emission in the range of from 2son to 5000 ~, preferably from 3000 to 4000 ~.
Examples of suitable light sources include carbon arc lamps, xenon lamps, W fluorescent lamps, low pressure mercury lamps and hlgh pressure mercury lamps which, in addition to ~isible l~i~ht, pro~ide a portion of ultraviolet light which is particularly effective for polymerisation. The time of exposure to the light depends on the nature o the light source.

- ~6 - ~

Irradiation may be carried out at room temperature or at elevated temperatures. Exceptionally high bond strengths are obtained if the laminate is heated to a surface temperature of from 50 to 150C, preferably from 70 to 120C before irradiation.
It is generally desirable to adjust the polymeris-able compound to the ini*iator system so that the starting temperature li~s within the range of from 50 to 200C, in particular from 70 to 120C (heat hardening).
Cross-linking to the compound used for the adhesive layer according to the inven*ion is generally carried out by heating to a temperature which is equal to or higher than the starting temperature of the polymerisation initiator. Heating of the adhesive compound is therefore generally not necessary if the polymerisation initiator system used is one which initiates polymerisation of the compound of the ambient temperature tcold hardening).
If the polymerisation initiator system is used in a microcapsuIar ~orm, activation o~ the polymerisation initiator system is effected by destroying the capsules mechanically, e.g. during the laminating process. When this form oE adhesive compound according to the invention is used, the application of heat for the purpose of cross-linking may be desirable, depending on the nature of the polymerisation initiator.
The sources of heat used for heat hardening the laminate produced according to the invention may be, for example inrared dark radiators, in~ra red light radia-tors, infra red copying radiators, microwa~e radiators, hot air blowers, heating rollers, heating plates or ~ 1 3 ~87~

similar sources of heat. Carbon arc lamps, low pressure mercury lamps and high pressure lamps emitting thermal radiation in addition to a proportion of W light.and visible light are also suitable.
The process according to the invention is parti-cularly suitable for the manufacture of tamperproof plastics coated cards which are used, for example, as credit cards by banks, oil companies, airlines or retail trading companies.but which may also be used as company identification cards, voters cards, social security cards or similar identification cards. The lamination produced by the process according to the invention is bonded indissolubly to the enveloped infor-mation carrier and thus preven*s every attempt at subsequent alteration of the informa,ion on the carrier.
Once th foil has been applied, it cannot be removed without complete destruction of the information carrier.
The following examples serve to explain the process of the invention in more detail.

7 ~

Hardenable composition 1 An acrylate containing urethane groups is prepared by the reaction of 222 g of isophorone diisocyanate, 116 g of hydroxyethyl acrylate and 1050 g of polyester diol having a hydroxyl number of 56 which has been prepared by solvent-~ree condensation of adipic acid and ethylene glycol.
After introduction of all the isocyanate, 0.2 g of tin octoate and 0.15 g of di-tert~-butyl hydro quinone into the reaction vessel, the hydroxyethyl-acrylate is added dropwise under a stream of dry air at such a rate that the tempexature does not rise above 65C. When the isocyanate content reaches about 12 %
by weight, the polyesterdiol is added and the reaction mixture is stirred at 60C until the isocyanate content is 0.1 % by weight. An odourless, colourless, viscous resin is obtained.

Hardenable composition 2 75 g of the composition from Example 1 are mixed with 25 g of tetraoxylated trimethylolpropane trisacry-late.

Hardenable com osition 3 P
A polyester acrylate is obtained by aæeitriouc distillation of a polyester which has ~een prepared by solvent~free condensation and acrylic ac~d.
166 g of phthalic acid, ~92 g of adipic acid, 275 g of trimethylolpropane and 127 g of ethylene glycol are heated slowly to a temperature o 180 to 220C

under a stream of nitrcgen. When an acid number of 8 has been reached (mg KOH per g of substance), the reaction mixture is cooled and 460 g of toluene, 245 g of acrylic acid, 10 g of p-toluene sulphonic acid, 1 g of p-methoxyphenol and 1.5 g of di-tertO-butyl-hydroquinone are added. Water is then removed azeo-tropocally under a stream of air. When the acid number is below 15, the solvent is distilled off under vacuum and the residue is desorbed for one hour under a stream of air at about 10 Torr and 80C. A colourless, odourless resin is obtained.

Hardenable composition 4 75 g of the adhesive layer composition from Example 3 are mixed with 25 g of hexanediol bisacrylate.

Hardenable com~osition 5 A solution of 70 g of tetraethoxylated trimethylol-propane-trisacrylate and 30 g of polyvinyl ace*ate (calcuIated molecular weight 370 000) is prepared.

Hardenable composition 6 An unsaturated polyester is pre~ared by the usual method of solvent-free condensation at 160 to 180C
from 2320 g of fumaric acid, 4519 g of propylene glycol, 1440 g of,diethyleneglycol, 940 g of trimethylolpropane diallyl ether and 430 g of diethylene glycol monobutyl ether. A highly ~iscous, odourless resin is obtained.

Hardenable composi~io~ i 65 g of the adhesive layer composition rom Example 6 are mixed with 35 g of styrene.

6~

Example 1 100 g of each of the compositions 1 to 7 which are to be hardened by radical cross-linking are mixed with 5 g of benzoyl peroxide and 50 g of ethyl acetate.
The resuIting solutions are applied by means of coil or wore on a metal rod to a polyethylene ~oil which has been subjected to a corona discharge. A layer from 15 to 20 um in thickness is obtained after evaporation of the sol~ent.
The resulting foils are laminated in one case to one side of a document made of art printing paper and in the other case to both sides of a paper document bearing a recording on a photo~raphic layer, using in each case a commercial laminator at a roller temperature of 115C.
The laminates are subsequently placed between two metal plates which have been preheated to 1~0C, and they are then stored in a heating apparatus at 120C.
The laminates are cooled after a residence time of 10 minutes in the heating apparatus. On inspection, all of the laminates are found to be well bonded. Any attempt to separate the laminates mechanically or by heat in~ariably leads to destruction of the information carrier.

Example 2 100 g of each of the hardenahle compositions 1 to 5 are mixed with 1.5 g of benzyl dimethylketal, 4 g of benzophenone and 50 g of ethyl acetate. The subse-quent procedure is as described in Example 1.

1 :~ 6 ~
, ~ "

- 31 ~

Lamination is carried out at a roller temperature of 90C.
The laminates are su~sequently placed on an adjust-able conveyor belt to be hardened under a W radiator (80 Watt per cm at a distance oE 8 cm; e.g. a Hanovia radiator). Hardening of the sample containing the docu-ment of art paper is carried out under the conditions indicated in Table 1 below and hardening of the sample containing the photographic paper is carried out under the conditions indicated in Table 2.

Table 1 HardenableCross-linking conditions composition 1 4 m/min 2 4 m/min 3 2 m/min 4 2 mtmin 3 m/min Table ~

HardenableCross-linking conditions compositi n 1 2 m/min 2 2 m/min 3 0.5 m/min 4 0.5 m/min 1 m/min - 32 - ~

Any attempt to separate the laminate mechanically or by heat invariably results in destruction o~ the information carrier (inlet).

Hardenable composition 8 1.9 g of thiodiglycol, 0.25 g of p-methoxyphenol and 72 g of acrylic acid are added ta 150 g of bisphenol-A-bisglycidyl ether (epoxide equivalent 190~
and the mixture is stirred at a temperature of 70C under a stream of dry air until an acid number below 1 (mg KOH
per g of substance) is reached. A glass clear, viscous resin is obtained.

Hardenable c mposition 9 75 g of the hardenable composition 8 are mixed with 25 g of a tetraethoxyla-ted trimethylolpropane-trisacrylate.

Hardenable composition 10 3.8 g of thiodiglycol, 0.25 g of p-methoxyphenol and 144 g of acrylic acid are acLded to 380 g of bisphenol-~-bisglycidyl ether and stirred at a tempera-ture of 70~C under a stream of cLry air until an acid number below 1 (mg KCH per g of substance) is reached.
The reaction mixture is then cooled, 330 g o~ dichloro-methane and 1 ~ o tin octoate are added, and 84 g of hexamethylene diisocyanate are then added dropwise at 40C, at such a rate that the temperature does not exceed 40C. Stirring is continued until the isocyanate content is 0.1 % by weight~

~ ~ fi ~

Hardenable comp~sition 11 The method of preparation of composition 10 is repeated, but with the additi.on of.110 g of hexamethylene diisocyanate.

Hardenable comPosition~-12.
Preparation of the hardenable composition 10 is repeated, but with the addition of 126 g of hexamethylene diisocyanate.

Hardenable composition 13 3.4 g of thiodiglycol, 0.25 g of p-methoxyphenol and 144 g of acrylic acid are added to 344 g of hexa-hydrophthalic acid diglycidyl ester tepoxide equivalent 172). and the reaction mixture is stirred at the tempe-rature of 70C under a stream of dry air until an acid number below 1 (mg KOH per g of substance) is reached.
When the reaction mi~ture has been cooled to room temperature, 350 g of dichloromethane and 1 g of tin octoate are added, and 158 g of a triisocyanate obtained by the reaction oE 3 mol of hexamethylene diisocyanate and 1 mol of water are introduced dropwise at 40C.
The reaction mixture is then.stirred until the isocyanate content is 0.1 % by weight.

Hardenable com~_sition 14 The preparation of composition.13 is repeated but using 11~ g of a reaction product of 2.mol of tolylene diisocyanate and 1 ~ol of ethylene glycol.

l ~ 6187~

Haraenable composition 15 75 g of the hardenable compos.ition l3.are mixed with 25 g of tetraethoxylated.trimethylolpropane trisacrylate.

Hardenable c~osit~on 16.
70 g of hardenable composition 13 are mixed with 30 g of the adhesive layer composition from Example 3.

Hardenable composition 17 1.9 g of thiodiglycol, 0.25 g of p-methoxyphenol and 86 g of methacrylic acid are added to 190 g of bisphenol-A-bisglycidyl ether (epoxide equivalent 190) and the reaction mixture is stirred at 70C under a stream of dry air until an acid number below 1 (KOH per g of substance) is obtained. The reaction mixture is then cooled and 165 g of dichloromethane and 0.5 g of tin octoate are added. 42 g of hexamethylene diiso- -cyanate are added dropwise at ~0C at.such a rate that the temperature does not rise a.bove 40C. Stirring is continued until the isocyanate content ls 0..1 ~ by weight.

~xample 3 100 g of the hardened compositions 8 to 17 are mixed wlth 3 ~ of benzoyl peroxide. The resul.ting fo.rmulations are applied by means of a whirler ~300 revs/
min) to polyethylene ~oils which have previously been exposed to a corona discharge. When the layers obtained in this manner are partly dry, those ob~ained from the -~`! ```
- 35 - i hardenable composition 8 and 9 have a sli~htly tack handle while those obtained from compositions 10.to 17 form a physically dry surace. The coated foils are subsequently laminated to both sides of a photographic paper which carries a recording.
Lamination is carried out using a commercial laminator at a roller temperature of.115C..
The laminates are.subsequently placed between two glass plates which have been preheated to 120C and are hardened in a heating apparatus at 120C. After a residence time of 10 minutes in the apparatus, the laminates are cooled. Examination shows that all of the laminates are well bonded. Any attempt to separate the laminates mechanically or by heat result in destruction of the information carrier (inlet).

Example 4 The procedure is the same as in Example 3 except that 3 g of a benzpinacol silylether described in Example 1 of German Offenlegungsschrift No. 2,632,294 is used as polymerisation init:Lator. Examination shows that all of the laminates are well bonded. Any attempt to separate the laminates mechanically or by heat results in destruction of the information carrier (inlet).

Example 5 An apparatus consisting of a commercial laminator and a heating device equipped with.two infra red lamps . . ~

- 36 - ~

(250 Watt, Osram Siccalux lamps) is used. Immediately on leaving the laminating rollers of the laminator, the laminates can be passed through the heating devise so that both sides of the laminator are exposed to the radiators at a distance of 5 cm.
The laminator prepared in this apparatus contains a photographic paper carrying information. A polyethy-lene foil which has been exposed to a corona discharge and then coated as described in Examples 3 and 4 with the hardenable composition indicated in Table 3 below is laminated to both sides of the information carrier at a roller temperature o 115C and hardened. Table 3 gives the number of passages through the apparatus at a feed rate of 0.5 m/min.required to produce a perfect bond between the information carrier and the laminating foil.

Table 3 Hard~nable Initiator Number of com~osition ~assaqes __ _ 9 Benzoyl peroxide 3 - 4 9 Benzpinacol silyl ether 3 according to E~ample 19 16 Benzoyl peroxide 3 - 4 16 Benzpinacol silyl ether 2 - 3 ; according to Example 19 Any attempt to separate.the laminate mechanically, chemic~lly or by heat invariably leads.to destruction of the information carrier (inlet~.

7 ~

Example 6 To test the resistance of the laminates prepared according to Example.5 against treatment with solvents, the laminates are immersed, in each case for one hour at.50C, in chloroform, hexane, trichloroethylene, acetone, 5 % suIphuric acid and 5 ~ sodium hydroxide.
In none of the samples. is any damage or separation of the bond between laminating foil and information carrier observed.

Exam~le 7 Examples 3 to 6 were repeated but the polyethylene foil was replaced in one case by a composite foil of polyethylene/polyester (sa mm polyethylene, 12 mm polyester) and in another case by a composite foil of polyamide/polyethylene, both foils having the same thickness as the polyethylene foil. After a corona discharge treatment, the harde:nable compositions were applied to the polyethylene layer of the composite foil in the manner pre~iously described.
The resul~s were similar to those obtained in Examples 3 to 5. A perfect bond was obtained in both cases. Attempts to separate the laminate mechanically chemically ar by heat either ~ailed or led to destruction of the information carri.er.

Examplè 8 ~ g of the hard.enable composi*ions 8.ta 16 are mixed.with 1.5`g o~ benzyl dimethylketal:and 4 g of benzophenone. The resu~ting formulations are app.lied by 1 ~ 6:187~

means of a whirler (300 revs/min) to polyethylene foils which had previously been.subjected to a corona dis-charge. When the layers obtained.in this manner haue dried on the surface, the hardenable compositions 10 to 16 have a physically dry surface. The foils are then laminated to both sides of a photographic paper on which recordings have been made. Lamination is carried out in a commercial laminator at a.roller temperature of from 70 to 1~0C..
The individual samples of laminate are irradiated and examined as described below.

Example 8a The laminate.samples are placed on a conveyor belt wh:Lch is adjustable in speed and moved-under 5 W lamps in series (35 Watt/cm, HPQ lamps of Philips) once with their front surface facing the lamps and once with the back.surface facing the lamps.

Table 4 .

Har~enable composition. Irradiation conditions.in _ _ m/min _ 8 2.

2.. 5 12 3.. 5 13 .3 3.. 5 13Bl#7~

Example ,8b The samples of laminate are preheated under an inf,ra red lamp (250.Watt, distance 5 cm~ Osram Siccalux lamps). The preheating times are shown in Table 5 below.
The samples are then placed on a conveyor belt or adjustable speed and moved under a W lamp (80 Watt/cm) at a distance of 8 cm and a conveyor belt speed OL
5 m/min~ Table 5.shows the.num~er of passages.through the apparatus on each side of the lamine (front and back?: required to produce perfect and.solvent-resistance bonding of the laminate.

Table 5 Hardenable Preheating time Number of passages co osition in sec at.5 m/min mp ._ _ 12 23 .3 14 25 .3 ~ 2 Any attempt to separate.the laminates prepared in.
this manner by mechanical means or by heat leads to destruction of the information carrier (inlet). If the preheating treatment indicated in Table 4 is omitted, 11 1 B187~

the number of passages through the apparatus must be increased. if a perfect bond. is to be obtained.
This is illustrated in.the following examples 8c and 8d.

Example 8c-A laminate containing hardenable composition 11 is heated to a surace temperature of 95C in an infra red radiator and subsequently exposed on each.side to a high pressure mercury lamp (125 Watt~ from a distance of 8- cm. The time required to reach a fault-free bond is determined. The results are shown in the following Ta~le 5.

Example 8d The procedure is the same as in Example 8c except that preheating is omitted. The results are.shown in Table 6.

Table 6 ExampleIrradiation time in sec 3c 20 8d 190 Both laminates have a.perfect bond after irradia-tion. Attempts to separate the laminate mechanically or by heat invariably leads to destruction of the infor-mation carrier (inlet).

Example 8e An appa~atus consisting o~ a commercial laminator and an exposure device equipped with two hi~h pressure mercury lamps [125 Watt each) is used. As soon as the laminates have left the rollers of the laminator, they can be irradiated on both sides at a distance of 8 cm~
A laminate containing a photographic paper carrying information is produced in this apparatus. A polyethylene foil which has been exposed to a corona discharge and then coated with composition 9 which can be hardened by radiation is laminated to both sides of the informa-tion carrier at a roller temperature of 1 00C and irradiated. When the sample is fed through the apparatus at a rate of O . 5 m/min, a perfect bond between informa-tion carriex and laminating foil is obtained,-which cannot be separated either mechanically or by heat without destruction of t~e information carrier.

Example 8f To test the resistance to solvent treatment of the laminate produced according to Example 8e, the laminate is immersed, in each case for one hour at 50C, in chloroform, hexane, trichloroethylene, acetone, 5 ~,sulphuric acid and 5 % sodium hydroxide. In none of the samples is any damage or opening of the bond between laminatin~ foil and information carr.ier observed.

Example 8g Examples 8a to 8f were repeated except that the polyethylene foil was replaced in one case by a _ 8 7 ~

composite foil of polyethylene/polyester (50 mm poly-ethylene, 12 mm polyester) and in a second case by a composite foil of polyamide/polyethylene, using layers of the same thickness. The hardenable compositions were applied to the polyethylene layer of the composite foil in the manner described above after a corona discharge treatment. The results were similar to those obtained in Example 8a to 8f. A perfect bond was obtained in both cases. Attempts to dissolve the bond of the laminate mechanically or by heat or chemical means either failed or led to desctruction of the information carrier.

Claims (25)

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE
PROPERTY OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. A process for the production of tamper-proof documents by laminating an information carrier comprised of photographic paper on one or both sides with a foil, at least one foil being transparent, characterised in that a foil is provided with an adhesive layer of a composition which contains the substances necessary to make the adhesive layer hardnable by radical cross-linking by high energy radiation, by an initator activated by UV-light or thermally or an initiator activated by an accelerator, and said foil is laminated to one or both sides of an information carrier of photographic paper of the usual type which is provided with the required information, in such a manner that the hardnable composition comes into contact with the information carrier and the laminate is hardened, whereby the adhesion between the foil and the carrier cannot be separated without destroying information on the carrier.

2. Process according to claim 1, characterised by the use of an hardenable composition containing an ethylenically unsatur-ated monomeric, oligomeric or polymeric compound and, optionally, a photo-initiator.

3. Process according to claim 1, characterised by the use of a hardenable composition containing an ethylenically unsaturated monomeric, oligomeric or polymeric compound and a polymerisation initiator and, optionally, an accelerator.

4. Process according to claim 1, 2 or 3, characterised by the use of a monomeric, oligomeric or polymeric compound containing unsaturated groups.

5. Process according to claim 1, 2 or 3, characterised by the use of a monomeric, oligomeric or polymeric compound containing vinyl groups.

6. Process according to claim 1, 2 or 3, characterised by the use of a monomeric, oligomeric or polymeric compound containing acrylate and/or methacrylate groups.

7. Process according to claim 1, 2 or 3, characterised by an ethylenically unsaturated oligomeric or polymeric compound based on polyesters, ?, .beta.-unsaturated polyesters, polyethers, polyepoxides, polyurethanes, urethane modified polyethers and unsaturated polymers.

8. Process according to claim 1, 2 or 3 characterised by an ethylenically unsaturated polymeric compound comprising a urethane-modified (poly)epoxy(meth) acrylate.

9. Process according to claim 1, characterised in that a hardenable composition containing a polymeric thermoplastic film former in addition to an ethylenically unsaturated monomeric or oligomeric compound is used.

10. Process according to claim 1, characterised by the use of a hardenable composition containing a monomeric compound having at least one vinylically unsaturated group in addition to the ethylenically unsaturated oligomeric or polymeric compound.

11. Process according to claim 10, characterised by the additional use of a polymeric thermoplastic film former.

12. Process according claim 1 or 3, characterised by the use of a peroxidic polymerisation initiator.

13. Process according to claim 1 or 3, characterised by the use of a non-peroxidic polymerisation initiator of the type of ?, ?, ?, ? '-tetrasubstituted ethanes.

14. Process according to claim 1 or 3, characterised by the use of a polymerisation initiator having starting temperature in the region of up to 200°C.

15. Process according to claim 1 or 3, characterised by the use of a polymerisation initiator having a starting temperature in the region of from 60°C to 150°C.

16. Process according to claim 1 or 3, characterised in that a non-peroxidic polymerisation initiator chosen from benzpinacol silylethers or benzpinacol alkylethers is used.

17. Process according to claim 1 or 3, characterised in that the polymerisation initiator is used in a microcapsular form.

18. Process according to claim 1, characterised in that the foil covered with an adhesive layer consists of polyethylene and is optionally used in the form of a composite foil with other polymer foils.

19. Process according to claim 18, characterised in that the polyethylene foil is subjected to a corona discharge treatment before application of the adhesive layer.

20. Process according to claim 1, characterised in that the information carrier used is paper or a paper covered with one or more photographic layers.

21. Process according to claim 1, characterised in that lamination of the information carrier is carried out at a temper-ature of up to 150°C.

22. Process according to claim 21, characterised in that lamination of the information carrier is carried out at 70°C to 120°C.

23. Process according to claim 1, 2 or 3, characterised in that the laminate is heated to a temperature of up to 150°C for hardening with high energy radiation or UV radiation, and the preheated laminate is irradiated.

24. Process according to claim 1, 2 or 3, characterised in that when initiators activated by heat are used, the laminate is heated to a temperature which is equal to or higher than the starting temperature of the thermally activated polymerisation initiator.

25. Document which is proof against falsification, consisting of an information carrier carrying information and laminated with at least one transparent foil on one or both sides, characterised in that the foil carries an adhesive layer containing a polymer hardened by radical cross-linking, by high energy radiation, by an initiator activated by U.V.-light or by an initiator activated by an accelerator through which adhesive layer the foil is bonded to the surface of the information carrier of photographic paper of the usual type in such a manner that the hardened polymer layer is in contact with the information carrier, so that the hardened polymer layer cannot be separated from the information carrier without destruction of the information carrier and of the infor-mation container on it.