EP1328603A1 - Reactive adhesive with a low monomer content and with multistage hardening - Google Patents

Abstract

The invention relates to a solvent-free reactive adhesive or a reactive adhesive containing solvents, which has a low monomer content and which hardens in multiple stages. The reactive adhesive contains at least one polyurethane prepolymer (A) with a low monomeric polyisocyanate content (a) and at least one free functional group which is capable of reaction with a compound having at least one acid hydrogen atom, especially at least one isocyanate group; and at least one compound (B) with at least one radiation-polymerisable functional group. The reactive adhesive is suitable for producing composite materials and has a high degree of flexibility as well as good initial adhesion.

Description

 P a t e n t a n m e l g

"Low-monomer reactive adhesive with multi-stage curing"

The invention relates to a solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing, its production and its use as a laminating and coating adhesive for composite materials.

In practice, adhesives based on polyurethane (PU) prepolymers that have reactive end groups (reactive adhesives) are often used to produce composite materials, in particular composite foils. In particular, there are end groups which can react with water or other compounds which have an acidic hydrogen atom. This form of reactivity makes it possible to bring the reactive PU prepolymers in the processable state (usually liquid to highly viscous) to the desired location in the desired manner and by adding water or other compounds that have an acidic hydrogen atom ( in this case called hardener) harden.

In these so-called 2-component systems, the hardener is usually added immediately before application, with the processor only having a limited processing time after adding the hardener.

However, it is also possible to cure polyurethanes with reactive end groups without the addition of hardeners simply by reaction with atmospheric moisture (1-component systems). Such 1-component systems generally have the advantage over the 2-component systems that the often tedious mixing of the often viscous components before application is eliminated for the user.

The polyurethanes with reactive end groups usually used in 1K or 2K systems include, for example, the polyurethanes with preferably terminal isocyanate (NCO) groups. In order to obtain PU prepolymers with terminal NCO groups, it is customary to react polyfunctional alcohols with an excess of monomeric polyisocyanates, generally at least predominantly diisocyanates.

It is known that at the end of the reaction, regardless of the reaction time, a certain amount of the monomeric polyisocyanate used in excess remains. A content of monomeric polyisocyanate has a disruptive effect, for example, when it comes to volatile diisocyanates: adhesives / sealants and, in particular, PU-based hotmelt adhesives are processed at elevated temperature. The processing temperatures of hot melt adhesives are between 100 ° C and 200 ° C, those of laminating adhesives between room temperature and 150 ° C. Even at room temperature, volatile diisocyanates, such as IPDI or TDI, have a vapor pressure that should not be neglected. This noticeable vapor pressure is particularly serious when spraying, since significant quantities of isocyanate vapors can occur above the application device, which are toxic because of their irritating and sensitizing effects. The use of products with a high content of such volatile diisocyanates requires extensive measures on the part of the user to protect the person processing the product, in particular complex measures to keep the breathing air clean, prescribed by law through the maximum permissible concentration of working substances as gas, steam or suspended matter in the Air at the workplace ^'' updated MAK value list of the technical rule TRGS 900 of the Federal Ministry of Labor and Social Affairs).

Since protection and cleaning measures are generally associated with high financial investments or costs, there is a need on the part of the user for products which, depending on the isocyanate used, have the lowest possible amount of volatile diisocyanates.

In the context of the present text, "volatile" means substances which have a vapor pressure of more than about 0.0007 mm Hg or a boiling point of less than about 190 ° C (70 mPa) at about 30 ° C.

If, instead of the volatile diisocyanates, low volatility diisocyanates are used, in particular the widespread bicyclic diisocyanates, for example diphenylmethane diisocyanates, PU prepolymers or adhesives based thereon are generally obtained with a viscosity which is usually outside the range for simple Processing methods usable range. This also happens / or additionally if you want to reduce the monomer content by reducing the NCO / OH ratio. In these cases, the viscosity of the polyurethane prepolymers can be reduced by adding suitable solvents.

Another possibility for lowering the viscosity is to add an excess of monofunctional or polyfunctional monomers, for example monomeric polyisocyanates, as so-called reactive diluents. In the course of a later hardening process (after adding a hardener or by hardening under the influence of moisture), these are incorporated into the coating or adhesive bond.

While the viscosity of the polyurethane prepolymers can actually be reduced in this way, the generally incomplete conversion of the reactive diluent and, in principle, the presence of monomeric, unreacted starting polyisocyanate frequently leads to a content of free, monomeric polyisocyanates in the bond, which, for example, can "migrate" within the coating or adhesive bond, or in part also into the coated or bonded materials. Such migrating components are often referred to as "migrates" in specialist circles. Upon contact with moisture, the isocyanate groups of the migrates are continuously converted to amino groups. The content of the resulting amines, especially the primary aromatic amines, must be below the detection limit of 0.2 micrograms of aniline hydrochloride / 100 ml sample based on aniline hydrochloride (Federal Institute for Consumer Health Protection and Veterinary Medicine, BGW, after official collection of test methods according to § 35 LMBG - Examination of foods / Determination of primary aromatic amines in aqueous test foods).

Migrates are undesirable in the packaging sector, especially in food packaging. On the one hand, the migration of the migrates through the packaging material can lead to contamination of the packaged goods, on the other hand, depending on the amount of migratable free monomeric polyisocyanate, long waiting times are necessary before the packaging material is "Migrat-free" and may be used.

Another undesirable effect that can be caused by the migration of monomeric polyisocyanates is the so-called anti-sealing effect in the production of bags or carrier bags from laminated plastic films: Often they contain laminated plastic films a lubricant based on fatty acid amides. By reaction of migrated monomeric polyisocyanate with the fatty acid amide and / or moisture, urea compounds are formed on the surface of the film which have a melting point which can be above the sealing temperature of the plastic films. This creates an alien anti-seal layer between the film parts to be sealed, which counteracts a uniform seal seam formation.

However, not only the use of reactive adhesives that still contain monomeric polyisocyanate leads to problems, but also the fact that they are placed on the market. For example, substances and preparations that contain more than 0.1% free MDI or TDI fall under the Hazardous Substances Ordinance and must be labeled accordingly. The labeling requirement involves special measures for packaging and transport.

Reactive adhesives that are suitable for the production of composite materials should therefore have a suitable processing viscosity, but if possible should not release or contain any volatile or migrable substances into the environment. Furthermore, there is a requirement for such reactive adhesives that, immediately after application to at least one of the materials to be joined, after they have been joined, they have a sufficiently good initial adhesion, which prevents the composite material from separating into its original constituents or a displacement of the bonded materials against one another as far as possible prevented. In addition, however, such an adhesive bond should also have a sufficient degree of flexibility to withstand the various tensile and tensile loads to which the composite material which is still in the processing stage is usually exposed, without damage to the adhesive bond and without damage to the bonded material, to survive.

In the case of the conventional, solvent-free reactive adhesives known as prior art, there is a fundamental disadvantage that the adhesive properties of the reactive adhesive after application are unsatisfactory due to the low viscosity, and the adhesive bond must therefore not be subjected to any stresses until the final hardening, so that the composite material can maintains the shape intended with the adhesive. However, this requires long curing times, which often make the production of composite materials with such reactive adhesives uneconomical. One approach to avoid the disadvantages described above is to use a multi-stage curing reactive adhesive system in the manufacture of composite materials. Here, reactive adhesives are used which are subjected to a rapid, first curing reaction in a first stage by irradiation. The strength of the adhesive bond after this first hardening reaction should be such that it enables easy handling of the connected objects or materials. In a second curing stage, the adhesive then cures until it has reached the desired final strength.

This methodology is described, for example, in DE 40 41 753 A1 and relates to reactive contact adhesives, processes for their production and their use. The publication describes two-stage polymerizable coating compositions based on urethane, which can be cured by a content of UV-polymerizable acrylate groups in the course of a first curing stage to form a solidified, but still structurally deformable or embossable material, followed by irreversible consolidation in a subsequent second stage. To reduce the viscosity, monofunctional acrylates are added to the adhesive as a reactive thinner. The adhesive described has pressure tack after irradiation; the intended use of the contact adhesive described is the bonding of wood and / or plastic parts at up to about 70 ° C., preferably at room temperature.

It was an object of the present invention to provide a reactive adhesive with improved properties which is suitable for the production of composite materials, in particular for the production of film composites.

The reactive adhesive should provide sufficient flexibility of the adhesive connection after the adhesive bonding has been carried out and, after complete curing, should lead to composite materials with excellent strength values with respect to the adhesive connection. In particular, this reactive adhesive should not contain any low molecular weight compounds capable of migration or volatility.

The object of the invention is achieved by a solvent-free or solvent-containing low-monomer reactive adhesive with multi-stage curing, the at least one polyurethane prepolymer (A) with a low content of monomeric polyisocyanate (a) and at least one free one, for reaction with at least one acidic one Functional group containing hydrogen atom capable, in particular at least one isocyanate group, and contains at least one compound (B) with at least one functional group polymerizable by radiation.

The low-monomer reactive adhesive contains in particular a polyurethane prepolymer (A), obtainable by reacting a) at least one monomeric polyisocyanate (a), b) at least one polyol (b) c) optionally at least one compound (c) which can be polymerized both by radiation has functional groups as well as at least one acidic hydrogen atom and d) optionally at least one silicon-organic compound (d).

“Low-monomer reactive adhesive” is understood to mean a reactive adhesive with a content of less than 0.1% by weight of monomeric polyisocyanate (a). “Low content of monomeric polyisocyanate” means a content of less than 0.5% by weight. , preferably less than 0.3% by weight and particularly preferably less than 0.1% by weight of monomeric polyisocyanate (a), based on the overall composition of the polyurethane prepolymer (A).

A “polymerizable functional group” is understood to mean a group which can react by radical, anionic or cationic polymerization, polycondensation or polyaddition with a suitable further functional group while increasing the molecular weight of the molecule carrying it. In the case of an increase in molecular weight by free-radical polymerization, the functional group is generally preferably an olefinically unsaturated double bond. In the case of an increase in molecular weight by polycondensation, the functional group can be, for example, an acid group or an alcohol group; in the case of polyaddition, for example, isocyanate groups or epoxy groups are suitable as functional groups.

“Irradiation” is understood to mean irradiation with UV light or with electron beams. A functional group which can be polymerized by irradiation with UV light or with electron beams is, for example, a group with olefinically unsaturated ones Double bond. In the context of the present invention, olefinically unsaturated double bonds are preferred, such as those present in the derivatives of acrylic acid or styrene. The derivatives of acrylic acid, for example the acrylates and the methacrylates, are particularly suitable and preferred in the context of the present invention.

In the further course of the text, the terms "hardening", "hardening" or the like, as they are generally used by the person skilled in the art, are often used, as long as reference is made to the properties of an adhesive. The "curing" or "curing" of a composition containing polymerizable compounds is generally based on a polymerization reaction which is accompanied by at least an increase in the molecular weight of the compounds contained in the composition. However, crosslinking reactions usually also take place at the same time. The terms "hardening", "hardening" or similar terms in the context of the following text therefore refer to polymerization reactions as can occur within individual components of the composition in each case in connection with the term, for example the radiation-induced polymerization of a component bearing double bonds. The terms also refer to polymerization reactions as they can take place under various components of the composition under consideration, for example the reaction of a component carrying isocyanate groups with a component carrying OH groups. The terms also refer to polymerization reactions as they can take place between a component of the composition under consideration and a component entering the composition due to external influence, for example the reaction between isocyanate groups and air humidity.

The functional group capable of reacting with a compound having at least one acidic hydrogen atom is, for example, the isocyanate group or the epoxy group in the context of the present invention, the isocyanate group being particularly preferred.

A compound having an acidic hydrogen atom is understood to mean a compound which has an active hydrogen atom which can be determined by the Zerewittinoff test and is bound to an N, O or S atom. These include in particular the hydrogen atoms of water, carboxy, amino, imino, Hydroxy and thiol groups. Water is particularly preferred in the context of the present invention, or those compounds which have amino or hydroxyl groups or both, or mixtures of two or more thereof.

The polyurethane prepolymers (A) which can be used according to the invention can be prepared by reacting at least one monomeric polyisocyanate (a), or a mixture of two or more monomeric polyisocyanates, with at least one compound having at least one acidic hydrogen atom. Suitable monomeric polyisocyanates contain an average of two to at most about four isocyanate groups. In the context of the present invention, particular preference is given to using diisocyanates as the monomeric polyisocyanates. Examples of suitable monomeric polyisocyanates are: 1, 5-naphthylene diisocyanate, 2,2'-, 2,4- and / or 4,4'-diphenylmethane diisocyanate (MDI), hydrogenated MDI (H ₁₂ MDI), ailophanates of MDI, xylylene diisocyanate ( XDI), tetramethylxylylene diisocyanate (TMXDI), 4,4'-diphenyldimethylmethane diisocyanate, di- and tetraalkylene diphenylmethane diisocyanate, 4,4'-dibenzyl diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, the isomers of tolylene diisocyanate (methylene diisocyanate), 1-tolylene diisocyanate -2,4-diisocyanato-cyclohexane, 1,6-diisocyanato-2,2,4-trimethylhexane, 1,6-diisocyanato-2,4,4-trimethylhexane, 1-isocyanatomethyl-3-isocyanato-1,5,5 trimethylcyclohexane (IPDI), chlorinated and brominated diisocyanates, phosphorus-containing diisocyanates, 4,4'-di-isocyanatophenylperfluoroethane, tetramethoxybutane-1,4-diisocyanate, butane-1,4-diisocyanate, hexane-1,6-diisocyanate (HDI ), Dicyclohexylmethane diisocyanate, cyclohexane-1, 4-diisocyanate, ethylene diisocyanate, phthalic acid bis-isocyanato-ethyl ester, also diisocyanates with rea cationic halogen atoms, such as 1-chloromethylphenyl-2,4-diisocyanate,

1-bromomethylphenyl-2,6-diisocyanate, 3,3-bis-chloromethyl ether-4,4'-diphenyldiiso-cyanate. Sulfur-containing polyisocyanates are obtained, for example, by reacting 2 mol of hexamethylene diisocyanate with 1 mol of thiodiglycol or dihydroxydihexyl sulfide. Other diisocyanates that can be used include trimethylhexamethylene diisocyanate, 1,4-diisocyanatobutane, 1, 12-diisocyanatododecane and dimer fatty acid diisocyanate. Particularly suitable are: tetramethylene, hexamethylene, undecane, dodecamethylene, 2,2,4-trimethylhexane-2,3,3-trimethyl-hexamethylene, 1,3-cyclohexane, 1,4-cyclohexane, 1,3 - or 1, 4-tetramethylxylene, isophorone, 4,4-dicyclohexylmethane and lysine ester diisocyanate. Tetramethylxylylene diisocyanate (TMXDI), in particular m-TMXDI from Cyanamid, is very particularly preferred.

In a particular embodiment, mixtures of 2 or more monomeric polyisocyanates contain polyisocyanates with uretdione, isocyanurate, allophanate, biuret, Iminooxathizindione and / or oxadiazinetrione structure.

Polyisocyanates or polyisocyanate mixtures with an allophanate structure based on HDI, IPDI and / or 2,4 ^' - or 4,4 ^' - diisocyanatodicyclohexyimethane are particularly preferred. Polyisocyanates containing oxadiazinetrione groups can be prepared from diisocyanate and carbon dioxide.

Suitable at least trifunctional isocyanates are polyisocyanates which are formed by trimerization or oligomerization of diisocyanates or by reaction of diisocyanates with polyfunctional compounds containing hydroxyl or amino groups.

Isocyanates suitable for the production of trimers are the diisocyanates already mentioned, the trimerization products of the isocyanates HDI, MDI, TDI or IPDI being particularly preferred.

Also suitable, preferably in a mixture with other monomeric polyisocyanates, are blocked, reversibly capped polykisisocyanates such as 1,3,5-tris [6- (1-methyl-propylidene-aminoxycarbonylamino) -hexyl] -2,4,6-trixo -hexahydro-1, 3,5-triazine.

Also suitable for use are the polymeric isocyanates, such as those obtained as a residue in the distillation bottoms from the distillation of diisocyanates. The polymeric MDI, as is available in the distillation of MDI from the distillation residue, is particularly suitable.

In the context of the present invention, IPDI, HDI, MDI and / or TDI is preferably used as monomeric polyisocyanate (a) individually or in a mixture.

Suitable compounds having at least one acidic hydrogen atom are, for example, polyols (b). Polyols are understood to mean compounds which carry at least two hydroxy (OH) groups as functional groups. Suitable as polyol (b) is, for example, a polymer selected from a group comprising polyesters, polyethers, polyacetals or polycarbonates with a molecular weight (M _n ) of at least about 200 g / mol, or mixtures of two or more thereof, the terminal OH groups exhibit. Polyesters which can be used as polyol (b) for the preparation of the PU prepolymer (A) in the context of the present invention can be obtained in a manner known to the person skilled in the art by polycondensation of acid and alcohol components, in particular by polycondensation of a polycarboxylic acid or a mixture of two or more Polycarboxylic acids and a polyol or a mixture of two or more polyols.

In the context of the present invention, polycarboxylic acids suitable for the preparation of the polyol (b) can be based on an aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic base body and, if appropriate, in addition to the at least two carboxylic acid groups, one or more substituents which are non-reactive in the context of a polycondensation, for example Halogen atoms or olefinically unsaturated double bonds. Optionally, instead of the free carboxylic acids, their anhydrides (where they exist), or esters thereof with C ^ _δ - are monoalcohols, or mixtures of two or more thereof, used for polycondensation.

Suitable polycarboxylic acids are, for example, adipic acid, hydrophthalic succinic acid suberic acid, azelaic acid, sebacic acid, glutaric acid, glutaric anhydride, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylenetetra-, glutaric anhydride, maleic acid, maleic anhydride, fumaric acid, dimer fatty acids or trimer fatty acids or Mixtures of two or more of them. If necessary, minor amounts of monofunctional fatty acids can be present in the reaction mixture.

A large number of polyols can be used as diols for producing a polyester or polycarbonate which can be used as polyol (b). For example, these are aliphatic polyols with 2 to 4 OH groups per molecule. The OH groups can be bound either primary or secondary. Suitable aliphatic polyols include, for example, ethylene glycol, 1,2-propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 3, 2,3-butanediol, 1,4-butenediol, 1,4-butynediol , Pentanediol-1, 5, and the isomeric pentanediols, pentenediols or pentindiols or mixtures of two or more thereof, hexanediol-1, 6, and the isomeric hexanediols, hexenediols or hexindiols or mixtures of two or more thereof, heptanediol-1, 7 as well as the isomeric heptane, heptene or heptine diols, octanediol I, 8 and the isomeric octane, octene or octane diols, and the higher homologues or isomers of the compound mentioned, as is known to the person skilled in the art a gradual extension of the hydrocarbon chain by one CH ₂ group or by introducing branches into the carbon chain, or mixtures of two or more thereof.

Highly functional alcohols such as, for example, glycerol, trimethylol propane, pentaerythritol or sugar alcohols such as sorbitol or glucose, and oligomeric ethers of the substances mentioned with themselves or in a mixture of two or more of the compounds mentioned, for example polyglycerol with a degree of polymerization of about 2, are also suitable to about 4. In the higher functional alcohols, one or more OH groups can be esterified with monofunctional carboxylic acids having 1 to about 20 C atoms, with the proviso that on average at least two OH groups are retained. The higher-functionality alcohols mentioned can be used in pure form or, if possible, as the technical mixtures obtainable in the course of their synthesis.

Polyether polyols can also be used as polyol (b). Polyether polyols which are to be used as polyol (b) or for the preparation of polyesters suitable as polyol (b) are preferably obtained by reacting low molecular weight polyols with alkylene oxides. The alkylene oxides preferably have two to about four carbon atoms. Suitable examples are the reaction products of Ethylengiyk ^'ol, propylene glycol, the isomeric butanediols or hexanediols, as mentioned above, or mixtures of two or more thereof, with ethylene oxide, propylene oxide or butylene oxide or mixtures of two or more thereof. Furthermore, the reaction products of polyfunctional alcohols, such as glycerol, trimethylolethane or trimethylolpropane, pentaerythritol or sugar alcohols or mixtures of two or more thereof, with the alkylene oxides mentioned to form polyether polyols are also suitable. Polyether polyols obtainable from the reactions mentioned and having a molecular weight (M _n ) of from about 100 to about 3,000 g / mol, preferably from about 200 to about 2,000 g / mol, are particularly suitable. The polyether polyols mentioned can be reacted with the above-mentioned polycarboxylic acids in a polycondensation reaction to give the polyesters which can be used as polyol (b).

Also suitable as polyol (b) are polyether polyols, such as those formed in the manner described above. Polyether polyols are usually obtained by reacting a starter compound with at least two reactive hydrogen atoms with alkylene or arylene oxides, for example ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran or epichlorohydrin or mixtures of two or more thereof. Suitable starting compounds are, for example, water, ethylene glycol, propylene glycol-1, 2 or -1, 3, butylene glycol-1, 4, or -1, 3, hexanediol-1, 6, octanediol-1, 8, neopentylglycol, 1, 4-hydroxymethylcyclohexane , 2-methyl-1,3-propanediol, glycerin, trimethylolpropane, hexanetriol-1, 2,6, butanetriol-1, 2,4, trimethylolethane, pentaerythritol, mannitol, sorbitol, methylglycosides, sugar, phenol, isononylphenol, resorcinol, hydroquinone , 1, 2,2- or 1, 1, 2-tris- (hydroxyphenyl) -ethane, ammonia, methylamine, ethylenediamine, tetra- or hexamethyleneamine, triethanolamine, aniline, phenylenediamine, 2,4- and 2,6- Diaminotoluene and polyphenyl polymethylene polyamines, as can be obtained by aniline-formaldehyde condensation.

In the context of the present invention, a polyether polyol and / or polyester polyol with a molar mass of 200 to 4000, preferably from 200 to 2000 g / mol, or a mixture of polyether polyols and / or polyester polyols, is particularly suitable for use as polyol (b) meet the restrictive criterion of molar mass.

In a further embodiment, it is particularly advantageous if a mixture of one or more polyester polyols and one or more polyether polyols is used as the polyol (b). The various base polymers can differ, for example, in the molecular weight (M _n ) or in the chemical structure, or in both.

Also suitable for use as polyol (b) are polyether polyols which have been modified by vinyl polymers. Such products are available, for example, in which styrene or acrylonitrile or a mixture thereof is polymerized in the presence of polyethers.

Polyacetals are also suitable as polyol (b) or as a polyol component for the production of polyol (b). Polyacetals are understood to mean compounds as can be obtained by reacting glycols, for example diethylene glycol or hexanediol, with formaldehyde. Polyacetals which can be used in the context of the invention can also be obtained by the polymerization of cyclic acetals.

Polycarbonates are also suitable as polyol (b) or as polyols for the production of polyol (b). Polycarbonates can be produced, for example, by the reaction of the abovementioned polyols, in particular diols such as propylene glycol, 1,4-butanediol or 1,6-hexanediol, diethylene glycol, triethylene glycol or tetraethylene glycol or mixtures two or more of them can be obtained with diaryl carbonates, for example diphenyl carbonate or phosgene.

In addition to the polyols (b) mentioned hitherto, other compounds can also be used to prepare the polyurethane prepolymers (A) with a low content of monomeric polyisocyanate and at least one free functional group capable of reacting with at least one compound having at least one acidic hydrogen atom , for example amines but also water. The following are also specifically mentioned:

Succinic acid di-2-hydroxyethyl amide, succinic acid di-N-methyl- (2-hydroxyethyl) amide, 1,4-di (2-hydroxymethyl methylcapto) -2,3,5,6-tetrachlorobenzene, 2-methylene propanediol (1 , 3), 2-methylpropanediol- (1,3), 3-pyrrolidino-1,2-propanediol, 2-methylenepentanediol-2,4,3-alkoxy-1,2-propanediol, 2-ethylhexane-1,3- diol, 2,2-dimethylpropanediol-1, 3, 1, 5-pentanediol, 2,5-dimethyl-2,5-hexanediol, 3-phenoxy-1, 2-propanediol, 3-benzyloxy-1, 2-propanediol, 2,3-dimethyl-2,3-butanediol, 3- (4-methoxyphenoxy) -1, 2-propanediol and hydroxymethylbenzyl alcohol; aliphatic, cycloaliphatic and aromatic diamines such as ethylenediamine, hexamethylenediamine, 1,4-cyclohexylenediamine, piperazine, N-methyl-propylenediamine, diaminodiphenylsulfone, diaminodiphenyl ether, diaminodiphenyldimethylmethane, 2,4-diamino-6-phenylaminodiamine, diaminodiamine diamine diamine diamine diamine diamine diamine diamine diamine diamine diamine diamine diamine diamine diamine diamine diamine

Diaminodiphenylmethane, aminodiphenylamine or the isomers of phenylenediamine; also carbohydrazides or hydrazides of dicarboxylic acids; Amino alcohols such as ethanolamine, propanolamine, butanolamine, N-methylethanolamine, N-methylisopropanolamine, diethanolamine, triethanolamine and higher di- or tri (alkanolamines); aliphatic, cycloaliphatic, aromatic and heterocyclic mono- and diaminocarboxylic acids such as glycine, 1- and 2-alanine, 6-aminocaproic acid, 4-aminobutyric acid, the isomeric mono- and diaminobenzoic acids as well as the isomeric mono- and diaminonaphthoic acids.

The polyol (b) is preferably reacted with the monomeric polyisocyanate (a) in a ratio of 1:> 2.

In order to avoid the formation of higher molecular weight oligomers, a high stoichiometric excess of monomeric polyisocyanates is advantageously used in relation to the Polyols chosen. An NCO: OH ratio of 2: 1 to 10: 1 is preferred, in particular an NCO: OH ratio of 3: 1 to 7: 1 is preferred.

The reaction can take place, for example, in the presence of solvents. In principle, all solvents commonly used in polyurethane chemistry can be used as solvents, in particular esters, ketones, halogenated hydrocarbons, alkanes, alkenes and aromatic hydrocarbons. Examples of such solvents are methylene chloride, trichlorethylene, toluene, xylene, butyl acetate, amyl acetate, isobutyl acetate, methyl isobutyl ketone, methoxybutyl acetate, cyclohexane, cyclohexanone, dichlorobenzene, diethyl ketone, di-isobutyl ketone, dioxane, ethyl acetate, ethyl acetate, ethylene glycol monoethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetylethylacetyl Ethyl Acetyl Ethyl Acetyl Ethyl Ethyl Acetate Ethyl Acetyl Ethyl Ethyl Acetyl Ethyl Acetate Ethyl Acetate Ethyl Acetate Ethyl Acetate , Hexane, isobutyl acetate, isooctane, isopropyl acetate, methyl ethyl ketone, tetrahydrofuran or tetrachlorethylene or mixtures of two or more of the solvents mentioned. If the reaction components themselves are liquid or at least one or more of the reaction components form a solution or dispersion of further, insufficiently liquid reaction components, the use of solvents can be dispensed with entirely. Such a solvent-free reaction is preferred in the context of the present invention.

The temperature is usually raised to accelerate the reaction. As a rule, the temperature is raised to about 40 to about 80 ° C. The onset of exothermic reaction then causes the temperature to rise. The temperature of the batch is kept at about 70 to about 110 ° C, for example at about 85 to 95 ° C or in particular at about 75 to about 85 ° C, if necessary the temperature is adjusted by suitable external measures, for example heating or cooling.

To accelerate the reaction in polyurethane chemistry, customary catalysts can optionally be added to the reaction mixture. The addition of dibutyltin dilaurate or diazabicyclooctane (DABCO) is preferred. If it is desired to use a catalyst, the catalyst is generally added to the reaction mixture in an amount of about 0.001% by weight or about 0.01% by weight to about 0.2% by weight, based on the overall batch ,

The reaction time depends on the polyol (b) used, on the monomeric polyisocyanate (a), on the reaction temperature and on the catalyst which may be present. The total reaction time is usually about 30 minutes to about 20 hours. The low content of monomeric polyisocyanate (a) in the polyurethane prepolymer (A) is achieved by removing the monomeric polyisocyanate (a) from the reaction product after the reaction of at least one monomeric polyisocyanate (a) with at least one polyol (b). The purification step can be carried out according to processes known per se, such as distillation, extraction, chromatography or crystallization processes, as well as from combinations of these processes.

When using lower alkanediols as polyol (b), it has proven useful to take advantage of the low solubility of the polyurethane prepolymer (A) in some solvents, in that after the polyol / polyisocyanate reaction has ended, a non-solvent for the polyurethane prepolymer (A ) is added, which is also a solvent for the monomeric polyisocyanate. As a result, the polyurethane prepolymer (A) is precipitated from the reaction mixture and freed from unreacted monomeric polyisocyanate by filtration or by centrifugation. This method is particularly useful when the less volatile monomeric polyisocyanates such as MDI are to be used. Non-solvents are in particular non-polar aprotic organic solvents such as e.g. Ethyl acetate, chlorobenzene, xylenes, toluene, or in particular boiling-point spirit.

When using volatile monomeric diisocyanates as monomeric polyisocyanate (a) such as e.g. With TDI, TMXDI, IPDI, XDI, HDI, the excess monomeric polyisocyanate (a) can also be removed from the reaction mixture by distillation. For this purpose, the distillation is preferably carried out in vacuo with the aid of a thin-film evaporator or a thin-film evaporator. such

Distillation processes are e.g. in the plastics handbook volume 7, "Polyurethane", G.W. Becker (editor), Hanser-Verlag, Munich, 3rd edition 1993, page 425.

Another possibility of removing the monomeric polyisocyanate (a) from the reaction mixture is the selective extraction of the monomeric polyisocyanate (a), for example using supercritical carbon dioxide or other supercritical aprotic solvents. This extraction method is known for example from WO-97/46603.

In this way, a polyurethane prepolymer (A) with a low content of monomeric polyisocyanate (a) is obtained which bears two functional groups through which Reaction with a compound having at least one acidic hydrogen atom are polymerizable.

In a preferred embodiment of the invention, the polyurethane prepolymer (A) belongs to the group of NCO-terminated polyurethane prepolymers, obtainable by reacting polyols with IPDI, MDI, HDI and / or TDI.

In a further preferred embodiment, the polyurethane prepolymer (A) belongs to the group of NCO-terminated PU prepolymers, obtainable by reacting a mixture of a polyether polyol and / or polyester polyol with a molecular weight of about 800 to about 2000 and a polyether polyol and / or polyester polyol with a molecular weight of about 200 to about 700 with IPDI, MDI, HDI and / or TDI.

The PU prepolymers (A) obtained in this way are freed from excess monomeric polyisocyanate (a), preferably by the thin-film distillation process, and, after this cleaning step, have a residual content of less than 0.5% by weight of monomeric polyisocyanate.

If appropriate, a compound (c) is used to produce the PU prepolymer (A), which has both at least one functional group which can be polymerized by irradiation and at least one acidic hydrogen atom.

Irradiation is understood to mean, in particular, irradiation with UV light or with electron beams. Compound (c) particularly preferably has, as a functional group polymerizable by irradiation with UV light or with electron beams, a group with an olefinically unsaturated double bond. The molar mass of compound (c) is in the range from 100 to 15,000 g / mol, preferably from 100 to 10,000 g / mol and particularly preferably from 100 to 8000 g / mol.

Suitable for use as compound (c) are all polymeric compounds which can usually be used in adhesives, for example polyacrylates, polyesters, polyethers, polycarbonates, polyacetals, polyurethanes, polyolefins, or rubber polymers such as nitrile or styrene / butadiene rubber, provided that they contain at least one by irradiation functional group polymerizable with UV light or with electron beams and having at least one acidic hydrogen atom. However, polyacrylates, polyester acrylates, epoxy acrylates or polyurethane acrylates are preferably used as compound (c) for the preparation of the polyurethane prepolymer (A), since the polymers mentioned offer a particularly simple possibility of attaching the functional groups required according to the invention to the polymer molecule.

Polyacrylates bearing OH groups are particularly suitable as compound (c). Such polyacrylates can be obtained, for example, by polymerizing ethylenically unsaturated monomers which carry OH groups. Such monomers are obtainable, for example, by the esterification of ethylenically unsaturated carboxylic acids and difunctional alcohols, the alcohol generally being only in a slight excess. Suitable, ethylenically unsaturated carboxylic acids are, for example, acrylic acid, methacrylic acid, crotonic acid or maleic acid. Corresponding acrylate esters or hydroxyalkyl (meth) acrylates carrying OH groups are, for example, 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 3-hydroxypropyl acrylate or 3-hydroxypropyl methacrylate or mixtures of two or more thereof.

The molar ratios between the monomeric polyisocyanate (a), the polyol (b) and optionally the compound (c) are such that after component (a) has reacted with (b) and then the excess monomeric polyisocyanate (a) has been removed. the PU prepolymer (A) still contains 1 to 30% by weight, preferably 1 to 20% by weight, of free NCO groups. If, in addition to (a) and (b), the compound (c) is used to prepare the PU prepolymer (A), (A) contains 1 to 20% by weight, preferably 1 to 10% by weight and particularly preferably 1 up to 5% by weight of free NCO groups. For the content of free NCO groups, it is irrelevant whether in a step reaction in a first step (a) with (b) or (c) and in a second step this reaction product with (c) or (b) is further implemented, or in a so-called "one-pot reaction" (a), (b) and (c) are implemented simultaneously with one another.

The reaction ratio of components (a), (b) and (c) is chosen so that both good adhesion and cohesion are achieved. The proportion of functional groups polymerizable by irradiation with UV light or with electron beams determines the initial strength and the proportion of functional groups reactive with a compound having at least one acidic hydrogen atom determines the final strength of the bond. Good results can be obtained, for example, if 1 to 90% of the functional groups present as terminal groups in the polymer by irradiation with UV light or are functional groups polymerizable with electron beams, preferably 5 to about 80%, and particularly preferably 8 to about 75%.

Under certain circumstances, in particular in the presence of water, for example on moist surfaces, the use of reactive adhesives based on polyurethane prepolymers with NCO end groups can lead to the development of carbon dioxide, which can have adverse effects on the surface structure, for example. Furthermore, such reactive adhesives often do not adhere to smooth, inert surfaces, for example to surfaces made of glass, ceramic, metal or the like, which in some cases makes it necessary to use a primer before applying the reactive adhesive. In order to enable a firm and permanent connection of reactive adhesives based on polyurethane and, for example, the surfaces mentioned above, an organic silicon compound, preferably an alkoxysilane group, is introduced into the polyurethane as the reactive end group.

In accordance with the above requirements, an alkoxysilane of the general formula I is optionally used as component (d) as organic silicon compound for the preparation of the polyurethane prepolymer (A):

XA-Si (Z) _n (OR) ₃ . _n , (I).

X stands for a radical with at least one reactive functional group with acidic hydrogen, for example for a radical which has at least one OH, SH, NH, NH ₂ --COOH or anhydride group or a mixture of two or more such groups. In a preferred embodiment of the invention, X stands for OH, SH, H ₂ N- (CH ₂ ) ₂ -NH, (HO-C ₂ H ₄ ) ₂ N or NH ₂ , A for CH ₂ , CH ₂ -CH ₂ or CH ₂ -CH ₂ -CH ₂ or a linear or branched, saturated or unsaturated alkylene radical with 2 to about 12 C atoms or for an arylene radical with about 6 to about 18 C atoms or an arylene alkylene radical with about 7 to about 19 C - Atoms or a siloxane radical substituted with alkyl, cycloalkyl or aryl groups and having about 1 to about 20 Si atoms, Z stands for -O- CH ₃ , -CH ₃ , -CH ₂ -CH ₃ or for a linear or branched, saturated or unsaturated alkyl radical or alkoxy radical with 2 to about 12 C atoms and R represents -CH ₃ , - CH ₂ -CH ₃ , -CH ₂ -CH ₂ -CH ₃ or a linear or branched, saturated or unsaturated alkyl radical with 2 up to about 12 carbon atoms. In a preferred embodiment of the invention, the variable n stands for 0, 1 or 2. Examples of starting materials suitable as component (d) are H ₂ N- (CH ₂ ) ₃ -Si (O- CH ₂ -CH ₃ ) ₃ , HO-CH (CH ₃ ) -CH ₂ -Si (OCH ₃ ) ₃ , HO- (CH ₂ ) ₃ -Si (O-CH ₃ ) 3, HO-CH ₂ -CH ₂ -O-CH ₂ - CH ₂ -Si (OCH ₃ ), (HO-C ₂ H ₄ ) ₂ N- (CH ₂ ) ₃ -Si (O-CH ₃ ) ₃ , HO- (C ₂ H ₄ -O) ₃ -C ₂ H ₄ -N (CH ₃ ) - (CH ₂ ) 3-Si (O- C ₄ H ₉ ) ₃ , H ₂ N-CH ₂ -C ₆ H ₄ -CH ₂ -CH ₂ -Si (O-CH ₃ ) 3, HS- (CH ₂ ) 3-Si (O-CH ₃ ) 3, H ₂ N- (CH ₂ ) ₃ -NH- (CH ₂ ) ₃ -Si (OCH ₃ ) 3, H ₂ N-CH ₂ -CH ₂ -NH- (CH ₂ ) ₂ -Si (O-CH ₃ ) 3 , H ₂ N- (CH ₂ ) ₂ -NH- (CH ₂ ) 3-Si (OCH3) 3, HO-CH (C ₂ H ₅ ) -CH ₂ -Si (OC ₂ H ₅ ) ₃ , HO- ( CH ₂ ) 3-Si (OC ₂ H ₅ ) 3, HO-CH ₂ -CH ₂ -O-CH ₂ -Si (OC ₂ H ₅ ) ₃ , (HO-C ₂ H ₄ ) ₂ -N- (CH ₂ ) 3-Si (OC ₂ H ₅ ) ₃ , H ₂ N-CH ₂ -C ₆ H ₄ -CH ₂ -CH ₂ -Si (OC ₂ H ₅ ) 3, HS- (CH ₂ ) ₃ -Si ( O- C ₂ H ₅ ) ₃ , H ₂ N- (CH ₂ ) 3-NH- (CH ₂ ) ₃ -Si (OC ₂ H ₅ ) 3, H ₂ N-CH ₂ -CH2-NH- (CH ₂ ) ₂ -Si (OC ₂ H ₅ ) 3, H ₂ N- (CH ₂ ) ₂ -NH- (CH ₂ ) 3-Si (OC ₂ H ₅ ) 3.

As described above, in a preferred embodiment the monomeric polyisocyanate (a) is first reacted with the polyol (b) in a step reaction to form a reaction product with preferably terminal NCO groups. The excess monomeric polyisocyanate (a) is then removed by means of one of the cleaning processes described, preferably by means of thin-film distillation. The free NCO groups of the reaction product of monomeric polyisocyanate (a) with polyol (b) are optionally reacted with the compound (c), which has both polymerizable functional groups by irradiation and at least one acidic hydrogen atom and / or the alkoxysilane (d) ,

The one-pot reaction is also possible here, in which components (a) to (d) are allowed to react in only one step and then the excess monomeric polyisocyanate is removed by one of the cleaning methods described. Variants of the step reaction described above are also possible, for example the combination in the order (a) + (c) + (b) + (d) with subsequent removal of the excess monomeric polyisocyanate by one of the cleaning methods described.

The polyurethane prepolymer (A), which is optionally terminated with alkoxysilane and preferably still has free NCO groups, is then mixed with the other components.

As the compound (B), the reactive adhesives according to the invention contain at least one compound which has at least one and preferably two functional groups which can be polymerized by irradiation with UV light or with electron beams. As by radiation Functional groups polymerizable with UV light or with electron beams have compound (B) at least one group with olefinically unsaturated double bond.

Particularly suitable compounds (B) are di- or higher-functional acrylate or methacrylate esters. Such acrylate or methacrylate esters include, for example, esters of acrylic acid or methacrylic acid with aromatic, aliphatic or cycloaliphatic polyols or acrylate esters of polyether alcohols.

A large number of polyols can be used as polyols for the preparation of an acrylate or methacrylate ester which can be used as compound (B), as have already been described as polyol (b) for the preparation of the PU prepolymer (A).

Acrylate esters of aliphatic polyols with 2 to about 40 carbon atoms include, for example, neopentyl glycol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, trimethylol propane tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and (meth) acrylate esters of sorbitol and others sugar alcohols. These (meth) acrylate esters of aliphatic or cycloaliphatic diols can be modified with an aliphatic ester or an alkylene oxide. The aliphatic ester modified acrylates include, for example, neopentyl glycol hydroxypivalate di (meth) acrylate, caprolactone modified neopentyl glycol hydroxypivalate di (meth) acrylates and the like. The alkylene oxide-modified acrylate compounds include, for example, ethylene oxide-modified neopentyl glycol di (meth) acrylates, propylene oxide-modified neopentyl glycol di (meth) acrylates, ethylene oxide-modified 1,6-hexanediol (meth) acrylates or propylene oxide-modified 1,6-hexanediol (meth) acrylates or mixtures of two or more of them.

Acrylate monomers based on polyether polyols include, for example, neopentyl glycol-modified (meth) acrylates, trimethylolpropane di (meth) acrylates,

Polyethylene glycol di (meth) acrylates, polypropylene glycol di (meth) acrylates and the like. Trifunctional and higher functional acrylate monomers include, for example

Trimethylolpropane tri (meth) acrylate, pentaerythritol tri- and tetra (meth) acrylate,

Dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, caprolactone-modified dipentaerythritol hexa (meth) acrylate,

Pentaerythritol tetra (meth) acrylate, tris [(meth) acryloxyethyl] isocyanurate, caprolactone-modified tris [(meth) acryloxyethyl] isocyanurate or trimethylolpropane tetra (meth) acrylate or mixtures of two or more thereof. Among the di-, tri- or higher-functional acrylate monomers mentioned which can be used according to the invention as component B are di-, tri- and tetrapropylene glycol diacrylate, neopentylglycol propoxylate di (meth) acrylate,

Trimethylolpropane tri (meth) acrylate, trimethylolpropane monethoxytri (meth) acrylate and pentaerythritol triacrylate are preferred.

(Meth) acrylate esters based on polyols containing urethane groups can be prepared by reacting the polyols (b) already mentioned with the monomeric polyisocyanates (a) already mentioned, so that at least partially OH-terminated polyurethane prepolymers are formed which contain (meth) acrylic acid to be esterified to the corresponding mono- or diester.

In a particular embodiment, a compound is used as compound (B) which can be obtained by reacting (a) with (c). Isocyanatourethane acrylates, obtainable by reacting isocyanate, for example based on HDI, with acrylate polyols are particularly preferred.

Compounds (B) which are flowable at room temperature, in particular esters of acrylic acid or methacrylic acid, are particularly suitable as so-called “reactive thinners”. Particularly suitable compounds are, for example, the acrylic or methacrylic acid esters of aromatic, cycloaliphatic, aliphatic, linear or branched C. ^ o-Monoalcohols or from corresponding ether alcohols, for example n-butyl acrylate, 2-ethylhexyl acrylate, octyl / decyl acrylate, isobornyl acrylate, 3-methoxybutyl acrylate, 2-phenoxyethyl acrylate, benzyl acrylate or 2-methoxypropyl acrylate.

The compound (B) makes up up to about 80% by weight, but preferably less, for example about 40% by weight, 30% by weight or about 20% by weight in the reactive adhesive according to the invention. The use of smaller amounts is also possible, for example the reactive adhesive according to the invention can also contain only 10% by weight or an amount of about 0.5 to about 8% by weight of compound (B).

In addition to the PU prepolymer (A) and the compound (B), the reactive adhesive as component (C) can contain at least one photoinitiator, which initiates a polymerization of olefinically unsaturated double bonds under UV radiation. As component (C), therefore, a photoinitiator is generally used which is capable of initiating a radical polymerization of olefinically unsaturated double bonds when irradiated with light at a wavelength of about 215 to about 480 nm. In the context of the present invention, all commercially available photoinitiators which are compatible with the reactive adhesive according to the invention, ie which give at least largely homogeneous mixtures, are suitable in principle for use as component (C).

For example, these are all Norrish Type I substances that fragment. Examples include benzophenone, camphorquinone, quantacure (manufacturer: International Bio-Synthetics), Kayacure MBP (manufacturer Nippon Kayaku), Esacure BO (manufacturer: Fratelli Lamberti), Trigonal 14 (manufacturer: Akzo), photoinitiators from Irgacure ^® -, Darocure ^® - or Speedcure ^® series (manufacturer: Ciba-Geigy), Darocure ^® 1173 and / or Fi-4 (manufacturer: Eastman). Irgacure ^® 651, Irgacure ^® 369, Irgacure ^® 184, Irgacure ^® 907, Irgacure ^® 1850, Irgacure ^® 1173 (Darocure ^® 1173), Irgacure ^® 1116, Speedcure ^® EDB, Speedcure ^® ITX, Irgacure ^® 784 or Irgacure are particularly suitable ^® 2959 or mixtures of two or more of them. Also suitable is 2,4,6-trimethylbenzene diphenylphosphine oxide (Lucirin TPO, manufacturer: BASF AG), which can also be used in a mixture with one or more of the photoinitiators mentioned above.

Conventional low molecular weight photoinitiators can contribute to migratation in composite materials. The photoinitiators contained in the reactive adhesive themselves are suitable as migrates, but a further source of migratory agents are also fragments of the photoinitiators, as may arise when the reactive adhesive is irradiated with UV rays. Under certain circumstances, for example in the production of composite materials which are intended to serve as food packaging, the aim is to avoid as far as possible migratable compounds in the reactive adhesive. The content of migratable compounds in the reactive adhesive according to the invention can generally be reduced even further if the photoinitiator has a molecular weight which largely complicates or even prevents migration.

In the context of a preferred embodiment, component (C) therefore contains, at least in part, a photoinitiator which has a molar mass of more than about 200 g / mol. Commercially available photoinitiators that meet this condition are, for example, Irgacure® 651, Irgacure® 369, Irgacure® 907, Irgacure® 784, Speedcure® EDB, or Speedcure® ITX. However, photoinitiators which fulfill the above-mentioned condition with regard to their molar mass can also be obtained by reacting a low molecular weight photoinitiator which has at least one acidic hydrogen atom, for example an amino group or an OH group, with a high molecular weight compound having at least one isocyanate group (polymer-bound photoinitiators). Compounds which carry more than one photoinitiator molecule, for example two, three or more photoinitiator molecules, are preferably used as the component. Such compounds can be obtained, for example, by reacting a polyol with suitable polyisocyanates and photoinitiators with at least one acidic hydrogen atom.

All polyols mentioned above can be used as polyols, but in particular neopentyl glycol, glycerol, trimethylolpropane, pentaerythritol and their alkoxylation products with C ₂ . ₄ alkylene oxides. Also suitable as polyols, and particularly preferred in the context of the present invention, are the reaction products of trihydric alcohols with caprolactone, for example the reaction product of trimethylolpropane with caprolactone (Capa 305, from Interox, Cheshire, UK, molecular weight (M _n ) = 540).

In a preferred embodiment of the invention, component (C) contains a photoinitiator which can be obtained by reacting an at least trihydric alcohol with caprolactone to form a polycaprolactone having at least three OH groups and having a molecular weight of about 300 to about 900, and then the polycaprolactone is linked by means of a monomeric polyisocyanate with 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methylpropan-1-one.

Suitable monomeric polyisocyanates for reaction with the polyols mentioned are, for example, all the monomeric polyisocyanates (a) mentioned in the context of this text. However, the 2,4- and 2,6-isomers of tolylene diisocyanate (TDI) are particularly preferred, the isomers being able to be used in their pure form or as a mixture.

All photoinitiators which have an acidic hydrogen atom are suitable as photoinitiators for producing the polymer-bound photoinitiators. In the context of the present invention, particular preference is given to 1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methylpropan-1-one (Irgacure® 2959), which has a primary bonded OH group. If necessary, the photoinitiators which can be used in component (C) can also be prepared by using a deficit of photoinitiator molecules with at least one acidic hydrogen atom in the preparation of component A. This leads to a connection of the photoinitiator to a molecule of the PU prepolymer (A).

It is also possible to connect the photoinitiator to a polymer chain, for example to the PU prepolymer (A), by adding the photoinitiator having a corresponding functional group in monomeric form to the reactive adhesive, and then, for example, during a Storage time of the reactive adhesive with a corresponding polymeric component, for example PU prepolymer (A), reacts.

It is also possible to provide the photoinitiator with a functional group polymerizable by irradiation with UV light or with electron beams, the functional group polymerizable with UV light or with electron beams being connected to the photoinitiator, for example, by reacting the photoinitiator with an unsaturated carboxylic acid can be. Examples of suitable unsaturated carboxylic acids are acrylic acid or methacrylic acid. The reaction products of Irgacure® 2959 with acrylic acid or methacrylic acid are particularly suitable in the context of the present invention.

It is accordingly possible that a compound is used as component (C) which is both a photoinitiator and a functional group which can be polymerized by irradiation with UV light or with electron beams or a functional group capable of reacting with a compound having at least one acidic hydrogen atom , or both.

The reactive adhesive according to the invention contains component (C) in an amount of 0 to 15% by weight, based on the total reactive adhesive.

The reactive adhesive according to the invention can cure as a 1-component reactive adhesive after completion of a first curing stage by irradiation with, for example, electron beams or UV rays (in conjunction with a corresponding photoinitiator as component (C)) under the influence of atmospheric moisture to the required final strength. However, if a quick attainment of a certain ultimate strength, ie, a high one If the curing speed is required, for example in order to enable the bonded materials to be processed as quickly as possible, the curing speed based on curing by atmospheric humidity may be too low. In such cases, a hardener (D) can be added to the reactive adhesive before processing.

The invention therefore also relates to a reactive adhesive which, in the form of a two-component reactive adhesive as hardener (D), contains 0 to 60% by weight of a compound having at least two functional groups, each having at least one acidic hydrogen atom. The molar mass of (D) is in a range from 50 to 10,000 g / mol, preferably 50 to 6,000 g / mol and particularly preferably in a range from 50 to 3000 g / mol. A hardener (D) is preferably a compound having at least two functional groups, each having at least one acidic hydrogen atom, or a mixture of two or more such compounds which can react with the corresponding functional group of the PU prepolymer (A). In the context of the present text, the corresponding functional groups of the PU prepolymer (A) are understood to mean all the functional groups present in the PU prepolymer (A) which cannot be polymerized by irradiation under the conditions according to the invention, in particular isocyanate groups.

Primary or secondary amino groups, mercapto groups or OH groups are particularly suitable as functional groups with at least one acidic hydrogen atom that are reactive with the corresponding functional groups of the PU prepolymer (A). The compounds which can be used as hardeners (D) can each contain amino groups, mercapto groups or OH groups exclusively or in a mixture.

The reactive adhesive according to the invention preferably contains a compound having at least two OH groups as hardener (D).

The functionality of the compounds that can be used in the hardener (D) is generally at least about two. The hardener (D) preferably has a proportion of more highly functional compounds, for example with a functionality of three, four or more. The total (average) functionality of the hardener (D) is, for example, about two (for example if only difunctional compounds are used as the hardener (D)) or more, for example about 2.1, 2.2, 2.5, 2.7 , or 3. If appropriate, the hardener (D) can have an even higher functionality, for example about four or more. The hardener (D) preferably contains a polyol carrying at least two OH groups. All polyols (b) mentioned in the context of the present text, as well as reaction products or mixtures of the polyols (b) with (a), (c) or (d) are suitable for use as hardener (D), provided that they meet the restricting criterion meet the upper limit of the molecular weight.

The hardener (D) is generally used in an amount such that the ratio of functional groups of the component (A) reactive with the hardener (D) to groups of the hardener (D) reactive with corresponding functional groups of the component (A) is approximately 5: 1 to about 1: 1, in particular about 2: 1 to about 1: 1.

The reactive adhesive according to the invention generally has a viscosity of 100 mPa.s to 26,000 mPa.s at 70 ° C. (measured according to Brookfield, RVT DV-II digital viscosimeter, spindle 27). In preferred embodiments of the invention, the viscosity of the adhesive is selected so that it has a viscosity of about 1,000 mPas to about 5,000 mPas (measured according to Brookfield, RVT DV-II digital viscosimeter, spindle 27) at typical processing temperatures. Typical processing temperatures are, for example, approximately 25 to approximately 70 ° C. in the production of flexible packaging films (flexible packaging), approximately 70 to approximately 80 ° C. in the lamination of high-gloss films and approximately 80 to approximately 130 ° C. in textile applications.

If appropriate, the reactive adhesive according to the invention can also contain, as component (E), additives which may have a proportion of up to about 50% by weight of the total adhesive.

The additives (E) which can be used in the context of the present invention include, for example, plasticizers, stabilizers, antioxidants, adhesion promoters, dyes or fillers.

Examples of plasticizers used are plasticizers based on phthalic acid, in particular dialkyl phthalates, phthalic esters which have been esterified with an alkanol having from about 6 to about 14 carbon atoms being preferred. Di-isononyl or di-iso-tridecyl phthalate are particularly preferred. Also suitable as plasticizers are benzoate plasticizers, for example sucrose benzoate, diethylene glycol dibenzoate and / or diethylene glycol benzoate, in which about 50 to about 95% of all hydroxyl groups have been esterified, phosphate plasticizers, for example t-butylphenyldiphenylphosphate, polyethylene glycols and their derivatives, for example diphenyl ether, of poly (ethylene glycol), liquid resin derivatives, for example the methyl ester of hydrogenated resin, vegetable and animal oils, for example glycerol esters of fatty acids and their polymerization products.

Stabilizers or antioxidants which can be used as additives (E) in the context of the invention include phenols, sterically hindered phenols of high molecular weight (M _n ), polyfunctional phenols, sulfur- and phosphorus-containing phenols or amines. Phenols which can be used as additives in the context of the invention are, for example, hydroquinone, hydroquinone monomethyl ether 2,3- (di-tert-butyl) hydroquinone, 1,3,5-trimethyl-2,4,6-tris (3,5-di tert-butyl-4-hydroxybenzyl) benzene; Butylated hydroxytoluene (BHT), pentaerythritol tetrakis 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate; n-octadecyl-3,5-di-tert-butyl-4-hydroxyphenyl) propionate; 4,4-methylenebis (2,6-di-tert-butyl-phenol); 4,4-thiobis (6-tert-butyl-o-cresol); 2,6-di-tert-butylphenol; 2,6-di-tert-butyl-n-methylphenol; 6- (4-hydroxyphenoxy) -2,4-bis (n-octylthio) - 1,3,5-triazine; Di-n-octadecyl 3,5-di-tert-butyl-4-hydroxybenzylphosphonates; 2- (n-

OctyIthio) ethyl-3,5-di-tert-butyl-4-hydroxybenzoate; and sorbitol hexa [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate]; and p-hydroxydiphenylamine or N, N'-diphenylenediamine or phenothiazine.

The reactive adhesive according to the invention can contain adhesion promoters as component (E). Adhesion promoters are substances that improve the adhesive strength of materials to be combined. In particular, adhesion promoters are said to improve the aging behavior of bonds to moist atmospheres. Typical adhesion promoters are, for example, ethylene / acrylamide comonomers, polymeric isocyanates, reactive organosilicon compounds or phosphorus derivatives. In the context of the invention, phosphorus derivatives are preferably used as adhesion promoters, as are disclosed in WO 99/64529 (page 7, line 14 to page 9, line 5), for example 2-methacryloyloyethyl phosphate, bis (2-methacryloxyoxyethyl) ) phosphate, or mixtures thereof. (Meth) acrylate carboxylic acid-containing compounds can also be used as adhesion promoters. Compounds of this type are disclosed, for example, in WO 01/16244 (page 7, line 7 to page 8, line 31) or in WO 00/29456 (page 11, line 15 to page 12, line 2). Commercially available products are for example from UCB-Chemicals, B- 1620 Drugsbos, Belgium under the product class "Ebecryl", for example Ebecryl 168 or Ebecryl 170, available.

Further additives (E) can be included in the reactive adhesives according to the invention in order to vary certain properties. These can include, for example, dyes such as titanium dioxide, fillers such as talc, clay and the like. If necessary, small amounts of thermoplastic polymers can be present in the adhesives according to the invention, for example ethylene vinyl acetate (EVA), ethylene acrylic acid, ethylene methacrylate and ethylene-n-butyl acrylate copolymers, which optionally give the adhesive additional flexibility, toughness and strength. It is also possible to add certain hydrophilic polymers, for example polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl methyl ether, polyethylene oxide, polyvinyl pyrrolidone, polyethyloxazoline or starch or cellulose esters, in particular the acetates with a degree of substitution of less than 2.5, which, for example, increase the wettability of the adhesives.

The solvent-free or solvent-containing low-monomer reactive adhesive with multi-stage curing preferably contains

I) 10 to 98% by weight, preferably 10 to 80% by weight, of at least one polyurethane prepolymer (A),

II) 0.5 to 80% by weight, preferably 1 to 40% by weight, of at least one compound (B)

III) 0 to 15% by weight, preferably 1 to 8% by weight, of at least one photoinitiator (C),

IV) 0 to 60% by weight, preferably 0 to 40% by weight, of at least one hardener (D),

V) 0 to 50% by weight, preferably 1 to 20% by weight of additives (E), the sum of the constituents mentioned giving 100% by weight.

Depending on the required field of application, the reaction adhesive according to the invention can still contain up to 60% by weight of an inert solvent, which have already been described in the preparation of the polyurethane prepolymer (A).

The reactive adhesives according to the invention can be produced by customary techniques known to the person skilled in the art in the production of polymeric mixtures.

In principle, the reactive adhesive according to the invention can be used in the bonding of a wide variety of materials. The materials that can be glued include for example wood, metal, glass, plant fibers, stone, paper, cellulose hydrate, plastics such as polystyrene, polyethylene, polypropylene, polyethylene terephthalate, polyvinyl chloride, copolymers of vinyl chloride and vinylidene chloride, copolymers of vinyl acetate olefins, polyamides, or metal foils, for example made of aluminum, lead or Copper.

In a preferred embodiment, the reactive adhesive according to the invention is used in the production of composite materials. With a content of less than 0.1% by weight of monomeric polyisocyanate, the reactive adhesive according to the invention is particularly suitable for composite materials which are used in the food packaging sector.

Another object of the present invention is therefore also a method for producing composite materials, characterized in that a reactive adhesive according to the invention is used. In the context of a further preferred embodiment, the composite materials which can be produced with the aid of the reactive adhesive according to the invention are film composites which can be obtained by partially or completely gluing films.

The reactive adhesive according to the invention can be applied to the materials to be bonded, in particular the foils, using machines which are usually used for such purposes, for example conventional laminating machines. The application of the reactive adhesive in the liquid state to a film to be bonded to a laminate is particularly suitable. The film coated with the reactive adhesive in this way is laminated with at least one second film, optionally under pressure, and then irradiated with UV light or electrons.

In a special embodiment of the method, the film coated with the reactive adhesive is first transferred to an irradiation zone in which the polymerization reaction, that is to say the crosslinking of the individual components, is initiated by irradiation with ultraviolet radiation or electron radiation. The reactive adhesive according to the invention becomes sticky due to the radiation and the associated crosslinking reaction of the individual components contained in the reactive adhesive, for example contact sticky, but preferably pressure sensitive. After the irradiation process, the first film coated with the irradiated reactive adhesive is laminated with at least one second film, if appropriate with the application of pressure. This procedure is particularly advantageous when two films are to be glued together which are not transparent to the radiation required to initiate the polymerization.

While no further auxiliary substances are required to initiate crosslinking by means of electron beams, polymerization by means of UV light requires the presence of a photoinitiator (component E).

The described gluing and laminating processes can be repeated several times, so that laminates can be produced which consist of more than two glued layers.

The bonding and lamination processes described are usually carried out under a protective gas atmosphere, ie in the presence of inert gases such as nitrogen. Advantageously, however, the described bonding and laminating processes with the reactive adhesive according to the invention can also be carried out without any problems under a normal atmosphere, as typically prevails in the production halls.

The invention thus also relates to a composite material produced by a method according to the invention using a reactive adhesive according to the invention.

The reactive adhesive according to the invention can be applied to the surfaces to be bonded by all suitable methods, for example by spraying, knife coating, 3-4 roller application units in the case of using a solvent-free reactive adhesive or 2 roller application units in the case of using a solvent-containing reactive adhesive.

The invention is illustrated below by examples. Examples:

I. Production and properties of the PU prepolymers

PU prepolymer (1):

Low-monomer prepolymer based on an MDI-terminated polyether

Reaction of the monomeric polyisocyanate (a) with polyol (b) to the NCO adduct (1):

In a three-necked flask equipped with a stirrer, thermometer and drying tube

787.20 g of polyether diol (OH number: 130.2) heated to 40 ° C. and mixed with 712.80 g of liquid MDI. The mixture is allowed to react at 70-75 ° C for one hour. The remaining monomers are then distilled off using a thin-film distillation apparatus.

NCO value of the end product: 6.08% by weight; Monomer content: <0.1% by weight; Brookfield viscosity at 50 ° C: 8300 mPa.s

Implementation with a connection (c):

In a three-necked flask equipped with a stirrer, thermometer and drying tube

333.66 g of the above-mentioned NCO adduct (1) heated to 70 ° C. with stirring and then tert with 0.5 g of 2,6-di. butyl-4-methylphenol added. After five minutes, 16.35 g of hydroxypropyl acrylate are added. The mixture is allowed to react at 70-75 ° C for one hour and is then filled.

NCO value of the end product: 4.0% by weight (theoretical value: 4.3%), Brookfield

Viscosity at 70 ° C: 3900 mPa.s

PU prepolymer (2):

Low-monomer prepolymer based on an MDI-terminated polyether

Implementation with a connection (c):

In a three-necked flask equipped with a stirrer, thermometer and drying tube

273.21 g of the above-mentioned NCO adduct (1) heated to 70 ° C. with stirring and then tert with 0.5 g of 2,6-di. butyl-4-methylphenol added. After five minutes 26.79 g of hydroxypropyl acrylate are added. The mixture is allowed to react at 70-75 ° C for two hours and is then bottled.

NCO value of the end product: 2.4% by weight (theoretical value: 2.8% by weight), Brookfield viscosity at 70 ° C: 8600 mPa.s

PU prepolymer (3):

Low-monomer polyurethane prepolymer (A) based on a TDI-terminated polyether

Reaction of the monomeric polyisocyanate (a) with polyol (b) to the NCO adduct (2): 951.15 g of polyether diol (OH number: 185) are heated to 50 ° C. in a three-necked flask equipped with a stirrer, thermometer and drying tube and mixed with 548.85 g of 2,4-TDI. The mixture is allowed to react at 70-75 ° C for two hours. The remaining monomers are then distilled off using a thin-film distillation apparatus. NCO value of the end product: 8.52% by weight, monomer content: <0.1 TDI; Brookfield viscosity at 50 ° C: 6200 mPa.s

Implementation with a connection (c):

In a three-necked flask equipped with a stirrer, thermometer and drying tube, 263.76 g of the above-mentioned NCO adduct (2) are heated to 40 ° C. with stirring and then tert with 0.5 g of 2,6-di. butyl-4-methylphenoI added. After ten minutes, 36.24 g of hydroxypropyl acrylate are added. The mixture is allowed to react at 70-75 ° C for four hours and is then bottled. NCO value of the end product: 3.5% by weight (theoretical value: 3J5%); Brookfield viscosity at 70 ° C: 4000 mPa.s

PU prepolymer (4):

Low-monomer polyurethane prepolymer (A) based on an HDI-terminated polyether

Conversion of the monomeric polyisocyanate (a) with polyol (b) to the NCO adduct (3): 599.40 g of polyether diol (OH number: 334.1) at 70 ° C. in a three-necked flask equipped with a stirrer, thermometer and drying tube heated and mixed with 900.60 g HDI. The mixture is allowed to react at 100 ° C for two hours. The remaining monomers are then distilled off using a thin-film distillation apparatus. NCO value of the end product: 12.48% by weight, monomer content: <0.5% HDI; Brookfield viscosity at 20 ° C: 5100 mPa.s

Implementation with a connection (c):

In a three-necked flask equipped with a stirrer, thermometer and drying tube, 249.75 g of the above-mentioned NCO adduct are heated to 70 ° C. with stirring and then tert with 0.5 g of 2.6 di. butyl-4-methylphenol added. After five minutes, 50.25 g of hydroxypropyl acrylate are added. The mixture is allowed to react at 70-75 ° C for three hours and is then bottled. NCO value of the end product: 3.9% by weight (th. Value: 5.2% by weight); Brookfield viscosity at 70 ° C: 1400 mPa.s

PU prepolymer (5):

Low-monomer polyurethane prepolymer based on TDI and MDI-terminated polyether and polyester prepolymers

Reaction of the monomeric polyisocyanate (a) with polyol (b) to give the NCO adduct (4): 556.20 g of polyester diol (OH number: 137.0), 203.58 are in a three-necked flask equipped with a stirrer, thermometer and drying tube g of polyether diol 1 (OH number: 267.0) and 463.50 g of polyether diol 2_ (OH number: 110) and 88.20 g of polyester diol 2 (OH number: 110.0) heated to 50 ° C. and at 420 , 66 g of 2,4-TDI are added. The mixture is allowed to react at about 110 ^° C. for 90 minutes. 67.86 g of a dipropylene glycol 4,4'-MDI adduct (21.55% NCO) are then added. The mixture is allowed to react at 85 ° C for one hour and then bottled. NCO value of the end product: 4.2% by weight, monomer content: <0.5% by weight; Brookfield viscosity at 70 ° C: 5100 mPa.s

Implementation with a connection (c):

In a three-necked flask equipped with a stirrer, thermometer and drying tube, 749.28 g of the above-mentioned NCO adduct (4) are heated to 70 ° C. with stirring and then tert with 0.5 g of 2.6 di. butyl-4-methylphenol added. After five minutes, 50.72 g of hydroxypropyl acrylate are added. The mixture is allowed to react at 70-75 ° C for three hours and is then bottled. NCO value of the end product: 1.9% by weight (theoretical value: 2.0%); Brookfield viscosity at 70 ° C: 7000 mPa.s PU prepolymer (6):

Low-monomer prepolymer based on an MDI-terminated polyether

Production of the NCO adduct:

In a three-necked flask equipped with a stirrer, thermometer and drying tube, 1041.84 g of polyether diol (OH number: 130.2) are heated to 45 ° C. and 758.16 g of liquid MDI are added. The mixture is allowed to react at 70-75 ° C for one hour. The reaction product is then divided.

Some of the remaining monomers are distilled off using a thin-film distillation apparatus. NCO value of the end product: 5.83% by weight; Monomer content: 0.1% by weight MDI; Brookfield viscosity at 50 ° C: 7600 mPa.s The undistilled part contains 8.9% by weight MDI, NCO value: 8.19% by weight, Brookfield viscosity at 50 ° C: 5700 mPa.s.

• Production of the low-monomer dual-cure prepolymer (1): (reaction with (c))

In a three-necked flask equipped with a stirrer, thermometer and drying tube, 382.28 g of the above-mentioned distilled NCO adduct are heated to 70 ° C. with stirring and then tert with 0.2 g of 2,6-di. butyl-4-methylphenol added. After five minutes, 17.52 g of hydroxypropyl acrylate are added. The mixture is allowed to react at 70-75 ° ^{C. for} one hour and then bottled.

NCO value of the end product: 3.95% by weight (theoretical value: 4.14%), monomer content: 0.06% by weight MDI, Brookfield viscosity at 70 ° C: 2400 mPa.s.

• Production of the dual-cure prepolymer with standard monomer content (2): (implementation with (c))

In a three-necked flask equipped with a stirrer, thermometer and drying tube, 375.64 g of the above-mentioned non-distilled NCO adduct are heated to 70 ° C. with stirring and then tert with 0.2 g of 2,6-di. butyl-4-methylphenol added. After five minutes, 24.16 g of hydroxypropyl acrylate are added. The mixture is allowed to react at 70-75 ° C for one hour and then bottled.

NCO value of the end product: 5.45% by weight (theoretical value: 5.78%), monomer content: 4.3% by weight of MDI, Brookfield viscosity at 70 ° C: 1900 mPa.s. PU PrepoIvmer (7):

Low-monomer polyurethane prepolymer based on an HDI-terminated polyether

In a three-necked flask equipped with a stirrer, thermometer and drying tube, 867.60 g of polyether diol (OH number: 334.1) are heated to 70 ° C. and 932.40 g of HDI are added. The mixture is allowed to react at 100-110 ° C for two hours. The reaction product is then divided.

Some of the remaining monomers are distilled off using a thin-film distillation apparatus. NCO value of the end product: 12.50% by weight; Monomer content: <0.5% by weight HDI; Brookfield viscosity at 20 ° C: 5300 mPa.s The undistilled part contains 4.9 GW% HDI, NCO value: 14.32% by weight, Brookfield viscosity at 20 ° C: 4900 mPa.s.

Production of the low-monomer dual-cure prepolymer (3): (reaction with (c))

In a three-necked flask equipped with a stirrer, thermometer and drying tube, 334.16 g of the above-mentioned distilled NCO adduct are heated to 70 ° C. with stirring and then tert with 0.2 g of 2,6-Di. butyl-4-methylphenol added. After five minutes, 65.64 g of hydroxypropyl acrylate are added. The mixture is allowed to react at 70-75 ° C for three hours and then bottled. NCO value of the end product: 5.1% by weight (theoretical value: 5.22%), monomer content: 0.05% by weight HDI, Brookfield viscosity at 40 ° C: 1900 mPa.s.

• Production of the dual-cure prepolymer with standard monomer content (4): (implementation with (c))

In a three-necked flask equipped with a stirrer, thermometer and drying tube, 326.36 g of the above-mentioned non-distilled NCO adduct are heated to 70 ° C. with stirring and then tert with 0.2 g of 2,6-Di. butyl-4-methylphenol added. After five minutes, 73.44 g of hydroxypropyl acrylate are added. The mixture is allowed to react at 70-75 ° C for three hours and then bottled. NCO value of the end product: 5.60% by weight (theoretical value: 5.84%), monomer content: 1.4% by weight of HDI, Brookfield viscosity at 40 ° C: 1700 mPa.s. Production and properties of reactive adhesives

Reactive adhesive (1): 1-component reactive adhesive based on PU prepolymer (1)

With exclusion of moisture, 85.5 g of the PU prepolymer (1) with 9.5 g of tripropylene glycol diacrylate (compound (B)) and addition of 5 g of Irgacure 184 (photoinitiator (C)) are stirred at 70 ° C. until a homogeneous Mixture arises. Brookfield viscosity at 70 ° C: 2100 mPa.s

Reactive adhesive (2): 1-component reactive adhesive based on PU prepolymer (2)

With exclusion of moisture, 76 g of the PU prepolymer (2) are stirred at 70 ° C. with 19 g of tripropylene glycol diacrylate (compound (B)) and 5 g of Irgacure 184 (photoinitiator (C)) are added until a homogeneous mixture is obtained. Brookfield viscosity at 70 ° C: 1800 mPa.s

Reactive adhesive (3): 1-component reactive adhesive based on PU prepolymer (3)

With exclusion of moisture, 85.5 g of the PU prepolymer (3) with 9.5 g of tripropylene glycol diacrylate (compound (B)) and addition of 5 g of Irgacure 184 (photoinitiator (C)) are stirred at 70 ° C. until a homogeneous Mixture arises. Brookfield viscosity at 70 ° C: 4300 mPa.s

Reactive adhesive (4): 2-component reactive adhesive based on PU prepolymer (4)

In the absence of moisture, 86.75 g of the PU prepolymer (4) are stirred at 70 ° C. with the addition of 4.56 g of Irgacure 184 (photoinitiator (C)) until a homogeneous mixture is obtained. Brookfield viscosity at 70 ° C: 1400 mPa.s

8.69 g of a polyether polyol with an OH number of 391 are used as hardener (D). Reactive adhesive (5): 1-component reactive adhesive based on PU prepolymer (5)

With exclusion of moisture, 80.75 g of the PU prepolymer (5) with 14.25 g tripropylene glycol diacrylate (compound (B)) and addition of 5 g Irgacure 184 (photoinitiator (C)) are stirred at 70 ° C. until a homogeneous Mixture arises. Brookfield viscosity at 70 ° C: 4500 mPa.s

Reactive adhesive (6): 2-component reactive adhesive based on PU prepolymer (5)

With exclusion of moisture, 77.69 g of the PU prepolymer (5) with 13.71 g tripropylene glycol diacrylate (compound (B)) and the addition of 4.81 g Irgacure 184 (photoinitiator (C)) are stirred at 70 ° C. until a homogeneous mixture is created. Brookfield viscosity at 70 ° C: 4500 mPa.s

3J9 g of a polyether polyol with a viscosity of 4380 m.Pas (20 ° C.), an OH number of 391 and a silicon content of 4.9% by weight are used as hardener (D).

III. measurement methods

The monomeric polyisocyanate (a) in the polyurethane prepolymer (A) and in the reactive adhesives according to the invention was determined by means of gel permeation chromatography (GPC) or

High performance liquid chromatography (HPLC) using an in-house method. The viscometric data were determined using the "Brookfield Digital Viscometer RVTDV-II" viscometer, spindle 27.

IV. Laminating Attempts

The lamination tests were carried out on a lamination machine from Polytype. Irradiation was carried out by means of a UV system from Eltosch, equipped with a 120 W mercury lamp (UV dose = 180 mJ / cm ² ). The application weight of the reactive adhesive was ² g / m ^{2 in} each case The following was concealed:

Oriented polypropylene (OPP) film with a film thickness of 24

Micrometers,

Coextruded OPP film (coexOPP film) with a film thickness of 19

Micrometers,

Polyester film (PET film) with a film thickness of 12 micrometers,

Film made of polyethylene (PE film) with a film thickness of 17 micrometers,

Oriented polyamide (PA) film with a film thickness of 15 micrometers. It was always laminated first and then irradiated.

V. Group liability and seal seam liability

The bond adhesion and the seal seam adhesion are measured with a Zwick Z2.5 tensile testing machine on 15 mm wide strips. (Test speed: 100 mm / min.)

Abbreviations: VH stands for composite liability; SNH stands for seal seam adhesion. The results are given in N / 15 mm.

Verbund OPP / coexOPP

RK (3) 2.3; OPP-2.0; OPP crack 6.2; coex-2.6; OPP crack 6.6; coex crack crack crack

RK (4) 1, 6; OPP- 2.4; OPP crack 5.7; coex-3.1; OPP crack 5.8; coex-crack

Crack crack

Verbund: OPP / coexOPP

Composite: PET / PE

Compound: OPA / PE

VI. migration comparison

Reactive adhesives:

• MDI based:

Low monomer adhesive (M1):

Low-monomer dual-cure prepolymer (1) 98% + Irgacure 184 2%

Adhesive with standard monomer content (M2):

Standard dual-cure prepolymer (2) 98% + Irgacure 184 2%

• HDI-based:

Low monomer adhesive (H1):

Basis {Low-monomer dual-cure prepolymer (3) 98% + Irgacure 184 2%} 88.2% hardener (polyol mixture, OH number: 390, Brookfield viscosity: 4400 mPa.s) 11.8% Adhesive with standard monomer content (H2):

Basis {Low-monomer dual-cure prepolymer (4) 98% + Irgacure 1842%} 88.2% hardener (polyol mixture, OH number: 390, Brookfield viscosity: 4400 mPa.s) 11.8%

Extraction conditions:

All compounds were extracted as bags with 3% acetic acid (100 mL per 400 cm ² compound area), in accordance with BGW recommendation XXVIIl.

Determination of aromatic amines (MDA: diphenylmethane diamine): according to BGW recommendation XXVIIl, the network is considered to be migration-free if the determined one

Value is below 0.2 μg / 100 mL.

Determination of aliphatic amines (HDA: 1,6-diaminohexane):

The samples were analyzed by liquid chromatography after derivatization for the degradation product of HDI (1,6-diaminohexane).

OPA / PE

As can be seen from the tables above, the reactive adhesive systems according to the invention are migration-free after only one day.

Claims

claims

1. Solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing, comprising at least one polyurethane prepolymer (A) with a low content of monomeric polyisocyanate (a) and at least one free functional group capable of reacting with at least one acidic hydrogen atom, in particular at least one Isocyanate group, and at least one compound (B) with at least one functional group which can be polymerized by irradiation

2. Solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing according to claim 1, characterized in that the polyurethane prepolymer (A) is obtainable by reacting a) at least one monomeric polyisocyanate (a), b) at least one polyol (b) c) if appropriate at least one compound (c) which has both functional groups polymerizable by irradiation and at least one acidic hydrogen atom and d) optionally at least one organic silicon compound (d).

3. Solvent-free or solvent-containing low-monomer reactive adhesive with multi-stage curing according to claim 1 or 2, characterized in that it contains less than 0.1 wt .-% monomeric polyisocyanate.

4. Solvent-free or solvent-containing low-monomer reactive adhesive with multi-stage curing according to at least one of claims 1 to 3, characterized in that the polyurethane prepolymer (A) contains less than 0.5 wt .-% monomeric polyisocyanate.

5. Solvent-free or solvent-containing low-monomer reactive adhesive with multi-stage curing according to at least one of claims 1 to 4, characterized in that IPDI, HDI, MDI and / or TDI are used individually or as a mixture as monomeric polyisocyanate (a).

6. Solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing according to claim 2, characterized in that the polyol (b) is a polyether polyol and / or polyester polyol with a molar mass of 200 to 4000 g / mol, or a mixture of polyether polyols and / or Polyester polyols that meet the restrictive criterion of molar mass.

7. Solvent-free or solvent-containing low-monomer reactive adhesive with multi-stage curing according to claim 2, characterized in that the compound (c) is at least one compound with a molar mass of 100 to 15,000 g / mol, both of which are at least one by irradiation with UV light or functional group polymerizable with electron beams and also has at least one acidic hydrogen atom.

8. Solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing according to claim 7, characterized in that the compound (c) has a group with olefinically unsaturated double bond as a functional group polymerizable by irradiation with UV light or with electron beams.

9. Solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing according to claim 2, characterized in that the silicon-organic compound (d) at least one alkoxysilane of the general formula (I)

XA-Si (Z) _n (OR) ₃ . _n , (I), where

X for a radical with at least one reactive functional group with acidic hydrogen, for example at least one OH, SH, NH or COOH group or a mixture of two or more such groups, A for CH ₂ or for a linear or branched, saturated or unsaturated alkylene radical with 2 to about 12 C atoms or for an arylene radical with about 6 to about 18 C atoms or an arylene alkylene radical with about 7 to about 19 C atoms or a siloxane radical substituted with alkyl, cycloalkyl or aryl groups about 1 to about 20 Si atoms, Z for CH ₃ , O-CH ₃ or for a linear or branched, saturated or unsaturated alkyl radical or alkoxy radical with 2 to about 12 C atoms, R for CH ₃ or a linear or branched, saturated or unsaturated alkyl radical having 2 to about 12 carbon atoms and n is 0, 1 or 2.

10. Solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing according to claim 1, characterized in that compound (B) has at least one functional group polymerizable by irradiation with UV light or with electron beams.

11. Solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing according to claim 10, characterized in that compound (B) has at least one group with olefinically unsaturated double bond as polymerizable by irradiation with UV light or with electron beams functional groups.

12. Solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing according to at least one of claims 1 to 11, containing

I) 10 to 98% by weight of at least one polyurethane prepolymer (A),

II) 0.5 to 80% by weight of at least one compound (B)

III) 0 to 15% by weight of at least one photoinitiator (C),

IV) 0 to 60% by weight of at least one hardener (D),

V) 0 to 50% by weight of additives (E), the sum of the constituents mentioned giving 100% by weight.

13. Solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing according to claim 12, characterized in that (C) is a photoinitiator which is able to initiate a polymerization of olefinically unsaturated double bonds when irradiated with UV radiation.

14. Solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing according to claim 12, characterized in that the hardener (D) contains at least one compound with at least two functional groups, each with at least one acidic hydrogen atom.

15. Solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing according to claim 14, characterized in that the hardener (D) is at least one polyol carrying at least two OH groups.

16. Solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing according to claim 12, characterized in that the additives (E) include plasticizers, stabilizers, antioxidants, dyes or fillers.

17. Solvent-free or solvent-containing low-monomer reactive adhesive with multi-stage curing according to at least one of claims 1 to 16, characterized in that it has a viscosity of 100 mPas to 26,000 mPas at 70 ° C, measured according to Brookfield, RVT DV-II digital viscometer, spindle 27.

18. A process for the production of composite materials, characterized in that a solvent-free or solvent-containing, low-monomer reactive adhesive with multi-stage curing according to at least one of claims 1 to 17 is used.