CN1310733A - Monomer-poor polyurethane bonding agent having an improved lubricant adhesion - Google Patents

Abstract

The invention relates to a polyurethane bonding agent which has a low content of highly volatile residual monomers, which essentially forms no migrates and which has an improved lubricant adhesion. The invention also relates to a method for producing the inventive bonding agent and to an adhesive containing such a polyurethane bonding agent. In addition, the invention relates to the use of a low-viscous polyurethane bonding agent, said bonding agent carrying isocyanate groups (NCO groups), during the production of adhesives, especially adhesives containing one and two constituents, for example, provided for gluing web materials comprised of e.g. paper, plastic and/or aluminum, coatings, especially lacquers, dispersion paints, casting resins and shaped bodies.

Description

Low monomer-containing polyurethane adhesives with improved lubricant adhesion properties

The invention relates to a polyurethane adhesive and a method for preparing a low-viscosity isocyanate group-containing polyurethane adhesive, which contains only a small amount of volatile residual monomers and mainly forms non-migrating substances (Migrate) and have improved lubricant adhesion properties. Furthermore, the invention relates to the use of a low-tack polyurethane adhesive with isocyanate groups (NCO groups) for bonding strip-shaped materials such as paper, plastic and/or aluminium. , coatings, especially paints, colored emulsions, casting resins and molded bodies.

The use of polyurethane prepolymers with terminal isocyanate groups has been known for a long time. It can be chain-extended or cross-linked with suitable compounds, usually polyhydric alcohols, to form polymeric compounds by conventional methods. Polyurethane-prepolymers can be used in many fields such as the preparation of adhesives, coatings, casting resins and molded bodies.

To obtain isocyanate-terminated polyurethane prepolymers, polyhydric alcohols are usually reacted with excess polyisocyanates, generally at least predominantly diisocyanates. Molecular weight can be controlled at least approximately by the ratio of OH groups to isocyanate groups. When the ratio of OH groups to isocyanate groups is at or near 1:1, high molecular weight compounds generally result when the reaction is complete. For example, in the application of diisocyanate, when the above ratio is about 2:1, according to the statistical law, every 1 OH group is connected to 1 diisocyanate molecule, so under ideal conditions in the reaction process, no oligomers or chain extensions will be formed. .

In practice, however, most cases do not completely prevent the latter chain elongation described above. As a result, at the end of the reaction, a part of the components added in excess often remains regardless of the reaction time. If an excess of diisocyanate is added, a substantial portion of this component will generally remain, depending on the facts shown.

Now related to the volatile diisocyanate, when its content reaches a certain amount, it has a particularly large interference effect. Vapors from diisocyanates are often harmful to human health. When using these products with a high content of volatile diisocyanates, the user is required to take cost-intensive protective measures for the personnel who process these products, in particular cost-intensive protective measures for cleaning the air.

Generally speaking, the adoption of protection and purification measures requires huge financial investment and increased product costs. Therefore, from the perspective of the user, it is required that no matter what kind of isocyanate is used in the product, it should contain as little volatile diisocyanate as possible.

Within the scope of the present invention, the concept of "volatile" is understood as a substance which has a vapor pressure of more than about 0.0007 mmHg at about 30°C or a boiling point of less than about 190°C (70 mPa).

For example, adding a difficult-to-volatile diisocyanate to replace a volatile diisocyanate, especially the widely used bicyclic diisocyanate, such as diphenylmethane diisocyanate, generally results in a high-viscosity polyurethane adhesive. Viscosity values are beyond the range available for general processing methods. In the above cases the viscosity of the polyurethane prepolymers is reduced by adding suitable solvents, but this in turn contradicts the fact that adhesives of this type are often required to be free of solvents. Another way to avoid solubilization to reduce viscosity is to add an excess of monomeric polyisocyanate, which in the subsequent curing/curing process (addition of hardener or curing under moisture) enters the coating or bonding layer (reactive diluent).

Although the viscosity of the polyurethane-prepolymer is actually reduced in this way, usually the incomplete reaction of this reactive diluent will often leave a part of the adhesive layer or coating containing free monomeric polyisocyanate, which can The interior of a coating or bonding layer "migrates" or a portion can "migrate" into the material being coated or bonded. In the professional field, this part of the coating or adhesive layer is often called "migrate". On contact with moisture, the isocyanate groups of the migratory react continuously to form amino groups, and often the resulting aromatic amines can be carcinogenic.

Especially in the field of packaging, "migrants" are often intolerable because they move through the packaging material to contaminate the packaged goods, and when consuming these items, consumers are compelled to interact with these "migrants". "touch.

Such migration is therefore undesirable, especially in the field of packaging for the specialized packaging of foodstuffs.

In order to avoid the above-mentioned disadvantages, EP-A 0118065 proposes to prepare polyurethane prepolymers in a two-stage process. In a first step the monocyclic diisocyanate is reacted with a polyhydric alcohol having an OH group:isocyanate group ratio of less than 1, followed by a second step in the presence of the prepolymer prepared in the first step, Reaction of a bicyclic diisocyanate with a polyhydric alcohol having an OH group:isocyanate group ratio of less than one. A ratio of OH groups:isocyanate groups of 0.65 to 0.8:1, preferably 0.7 to 0.75:1 is suggested in step 2. The prepolymers obtained often also have high viscosities of 2500 mPas or 7150 mPas and 9260 mPas at high temperatures (75° C. or 90° C.). There is no mention of compatibility issues with lubricants.

EP-A0019120 relates to a two-step preparation method for preparing a plate-shaped material with elasticity and good weather resistance. In a first step, tolylene diisocyanate (TDI) is reacted with at least equimolar amounts of polyols, followed by reaction of the obtained reaction product with diphenylmethane diisocyanate (MDI) and polyols. The polycyanates thus obtained can be cured with water or with moisture. Although the described preparation method produces relatively low-viscosity products, the content of free volatile diisocyanate is always high (0.7% by weight) (in the presence of TDI), only with time-consuming and expensive The content of this substance can only be reduced after the excess volatile diisocyanate is removed by effective methods, such as thin layer distillation.

The unpublished German patent application DE 19749834.5 relates to a low-monomer polyurethane adhesive, which is a two-component polyurethane adhesive with a low monomer content and a low content of migratory components.

Films, such as those used to package food, often contain high levels of lubricants, such as erucamide (ESA), which can be present at levels above 400ppm in the film. Conventional adhesives used to bond the above-mentioned films into composite films often show a deterioration in composite adhesion as the lubricant content of the films to be bonded increases. Especially when using modern packaging machines with reasonable work, the preparation rate is increased by increasing the operating speed. The lubricant content of the film used at this time is much higher than that of the film used in the packaging machine with slow operation speed, which can often reach 600 ppm or higher. Many conventional adhesives have shown that their cohesion is insufficient when bonding films with lubricant contents of this magnitude. Its consequences often show that in the prepared composite film, especially after curing, the bond at the saddle shows many defects.

The object of the present invention is to provide a polyurethane adhesive which has a low viscosity and a low volatile diisocyanate content and which has a residual content of less than 1% by weight. In the case of tolylene diisocyanate (TDI), the residual content of volatile isocyanate should be less than 0.1% by weight.

A further object of the present invention is to provide a polyurethane adhesive which has a low content of "migratory" components, ie a monomeric polyisocyanate content which is as low as possible.

A further object of the present invention is to provide a process for the preparation of polyurethane adhesives having the above-mentioned properties.

A further object of the present invention is to provide a polyurethane adhesive and an adhesive which, in addition to the abovementioned properties, such as a volatile isocyanate content and low "migratory" components, additionally have improved lubricity agent compatibility, ie for example improved lamination adhesion or improved saddle seam adhesion when bonding films with high lubricant content.

The present invention relates to a kind of polyurethane adhesive containing a small amount of easily volatile monomers with isocyanate functional groups, the adhesive contains at least three components A, B and C, wherein:

a) containing as component A a polyurethane polymer with at least 2 isocyanate groups or a mixture of 2 or more polyurethane-prepolymers with at least 2 isocyanate groups, at least 1 polyurethane-prepolymer Polymers with at least 2 different isocyanate bonded forms or 2 different polyurethane-prepolymers in pairs with at least 2 different isocyanate bonded forms, of which at least 1 isocyanate bonded form is bonded to the other isocyanate groups It has lower reactivity towards reactive isocyanates compared to the form, and

b) contain as component B one at least difunctional isocyanate which does not contain N atoms other than NCO moieties or mixtures of two or more of such isocyanates, and

c) Containing, as component C, one isocyanate having at least two functional groups or a mixture of two or more isocyanates having an average of at least two functional groups, wherein each isocyanate molecule has at least one non-NCO N atom of the radical or urethane moiety.

Within the scope of the present invention, the term "low viscosity" is understood to mean a viscosity value (measured with a Brookfield viscometer) of less than 5000 mPas at 50°C.

Within the scope of the present invention, a "polyurethane adhesive" is understood to be a mixture of molecules containing at least 2 isocyanate groups per molecule, wherein the molecular component with a molecular weight greater than 500 is at least about 50% by weight, preferably at least About 60% by weight or at least about 70% by weight.

Add 1 polyurethane prepolymer with at least 2 isocyanate groups or a mixture of 2 or more polyurethane prepolymers with at least 2 isocyanate groups as component A, preferably by adding Obtained by the reaction of an at least difunctional isocyanate with a polyol component.

In the context of the present invention, a "polyurethane prepolymer" is to be understood as meaning a compound such as is obtained from the reaction of an isocyanate having at least two functional groups with a polyol component. The term "polyurethane-prepolymer" therefore includes not only compounds with relatively low molecular weight, such as those resulting from the reaction of excess polyisocyanates with polyols, but also oligomeric or polymeric compounds. Likewise "polyurethane-prepolymer" also includes other compounds such as those obtained by reacting diisocyanates with trihydric polyols or tetrahydric polyols in molar excess, the excess being polyol. In this case, 1 molecule of the resulting compound carries a plurality of isocyanate groups.

Molecular weights with respect to polymeric compounds are represented by number average molecular weights (Mn) unless otherwise specified.

Polyurethane-prepolymers generally used within the scope of the present invention have a molecular weight of from about 150 to about 15,000, or from about 500 to about 10,000, such as about 5,000, preferably from about 700 to about 2,500.

In a preferred embodiment of the invention, the polyurethane-prepolymer with 2 isocyanate groups, or at least one polyurethane present in a mixture of polyurethane-prepolymers with at least 2 or more isocyanate groups - A prepolymer having at least 2 different incorporations of isocyanate groups, at least one of which is less reactive towards reactive isocyanate groups than the other or some other incorporation. Isocyanate groups having a relatively low reactivity with reactive isocyanate groups (compared to at least one isocyanate group present in polyurethane adhesives) are hereinafter referred to as "low-reactivity isocyanate groups" and correspondingly with Reactive isocyanate-based compounds Isocyanate groups with strong reactivity are called "highly reactive isocyanate groups".

Therefore, within the scope of the present invention, if a difunctional polyurethane-prepolymer is added as component A, it has 2 different combinations of isocyanate groups, wherein one isocyanate group is more reactive than the other. Reactive isocyanates are highly reactive. Such polyurethane prepolymers are obtained, for example, by reacting compounds bearing 2 different, for example difunctional, isocyanate groups with dihydric alcohols. The reaction process is carried out by reacting an average of dihydric alcohols per molecule with compounds with different isocyanate groups per molecule.

Likewise, a trifunctional or higher functional polyurethane prepolymer can also be added to component A, wherein one molecule of the polyurethane prepolymer can have, for example, a different number of low-reactivity isocyanate groups and Highly reactive isocyanate groups.

In a further preferred embodiment of the invention, a mixture of two or more different polyurethane prepolymer compositions can be added as component A. In the polyurethane prepolymers in the mixture, the individual polyurethane molecules incorporate only one and the same isocyanate group. There must therefore be at least 2 different forms of polyurethane molecules present in the mixture, which are distinguished at least by the form of the isocyanate groups they carry. In this embodiment, at least 1 highly reactive isocyanate group and 1 lowly reactive isocyanate group must be present in the overall mixture of this type, i.e. 1 polyurethane molecule with at least 2 highly reactive isocyanate groups groups, a polyurethane molecule with at least 2 low-reactivity isocyanate groups. Likewise, mixtures containing, in addition to molecules carrying 1 or more isocyanate groups bound to the same, other molecules which not only carry 1 or more isocyanate groups bound to the same, but also carry 1 or more isocyanate groups bound to the same Multiple incorporation of different isocyanate groups.

Component A or at least part of component A can also be formed, for example, by a difunctional or polyfunctional alcohol with at least an equimolar amount of (for the OH groups of the difunctional or polyfunctional alcohol) its The reaction forms to about 400 low molecular weight diisocyanates.

In a preferred embodiment, the polyurethane prepolymer added as component A or the mixture of 2 or more polyurethane prepolymers contains at least one urethane group per molecule.

In another preferred embodiment of the present invention, component A is prepared by a reaction having at least 2 stages, wherein:

c) In a first stage, a polyurethane-prepolymer is prepared from at least a difunctional isocyanate and at least one first polyol component, wherein the NCO/OH ratio is less than 2 and in the polyurethane-prepolymer There are also free OH groups present, and

d) in a second stage, a further at least difunctional isocyanate is reacted with the polyurethane-prepolymer from the first stage,

Compounds in which the isocyanate groups of the isocyanate added in the second stage are more reactive than the isocyanate groups present in the first stage in the polyurethane prepolymer are more reactive.

In another preferred embodiment, further at least difunctional isocyanates are added in molar excess relative to the free OH groups of component A.

In another preferred embodiment, component A is prepared by at least 2 stage reactions, wherein:

e) In stage 1, a polyurethane-prepolymer is prepared from at least a difunctional isocyanate and at least one first polyol component, wherein the NCO/OH ratio is less than 2 and in the polyurethane-prepolymer There are also free OH groups present, and

f) in a 2nd stage, a further at least difunctional isocyanate and a further polyol component are reacted with the polyurethane-prepolymer from the 1st stage,

compounds wherein the isocyanate groups of the isocyanate added in stage 2 are more reactive towards reactive isocyanate groups than at least the major part of the isocyanate groups present in the polyurethane-prepolymer from stage 1 .

According to the present invention, the OH:NCO ratio in the second stage of preparation of component A is preferably from about 0.001 to less than 1:1, more preferably from 0.005 to about 0.8:1.

In a preferred embodiment of the invention, the OH:NCO ratio in the second stage is about 0.2 to 0.6:1.

In another preferred embodiment of the present invention, the OH:NCO in the first stage is less than 1, preferably 0.5 to 0.7:1, wherein optionally the above-mentioned ratios in the second stage can also follow this number.

Within the scope of the present invention, the term "polyol component" includes individual polyols or mixtures of 2 or more polyols from which polyurethanes can be produced. Polyols can be understood as polyhydric alcohols, that is, compounds with more than one OH group in the molecule.

Various polyols, such as aliphatic alcohols having 2 to 4 OH groups per molecule, can be added as polyol component for the preparation of component A. The OH group can be primary OH and secondary OH. Suitable aliphatic alcohols are, for example, ethylene glycol, propylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 1,8-octanediol Alcohols and their higher homologues or isomers, as they are known to the expert, extend the hydrocarbon chain by adding one _CH2 group at a time or by inserting branches into the carbon chain. Likewise suitable are alcohols having more functional groups, such as glycerol, trimethylolpropane, pentaerythritol, and the oligoethers of these substances or mixtures of two or more of the aforementioned ethers with one another.

Furthermore, for the preparation of component A, it is also possible to add reaction products of low molecular weight, polyfunctional alcohols with alkylene oxides, so-called polyethers. The alkylene oxides preferably have 2 to 4 C atoms. Suitable reaction products are, for example, ethylene glycol, propylene glycol, butanediol isomers or reaction products of hexylene glycol with ethylene oxide, propylene oxide and/or butylene oxide or both. or a mixture of several. Furthermore, reaction products of polyfunctional alcohols, such as glycerol, trimethylolethane and/or trimethylolpropane, pentaerythritol or sugar alcohols, with the abovementioned alkylene oxides to form polyether polyols are also suitable. Particularly suitable are polyether polyols having a molecular weight of from about 100 to about 10,000, preferably from about 200 to about 5,000. Most preferred within the scope of the present invention are polypropylene glycols having a molecular weight of from about 300 to about 2500. Also suitable as polyol component for the preparation of component A are polyether polyols, such as are obtainable by polymerization of tetrahydrofuran.

Polyethers are also obtainable in a known manner by reaction of starter compounds with 1 active H atom with alkylene oxides, such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran or epichlorohydrin or a mixture of 2 or more thereof.

Suitable starter compounds are, for example, water, ethylene glycol, 1,2-propanediol or 1,3-propanediol, 1,4-butanediol or 1,3-butanediol, 1,6-hexanediol, 1, 8-octanediol, neopentyl glycol, 1,4-hydroxymethylcyclohexane, 2-methyl-1,3-propanediol, glycerol, trimethylpropane, 1,2,6-hexanetriol Alcohol, 1,2,4-butanetriol, trimethylolethane, pentaerythritol, mannitol, sorbitol, methyl glycoside, sugar, phenol, isononylphenol, resorcinol, hydroquinone , 1,2,2- or 1,1,2-tris-(hydroxyphenyl)-ethane, ammonia, methylamine, 1,2-ethylenediamine, 1,4-butanediamine or 1,6- Hexamethylenediamine, triethanolamine, aniline, phenylenediamine, 2,4-diaminetoluene and 2,6-diaminetoluene and polyphenol polymethylene polyamine, which can be obtained by aniline-formaldehyde condensation reaction.

Polyethers modified by ethylene polymers are likewise suitable polyol components. Such products can also be obtained, for example, by polymerizing styrene or acrylonitrile or mixtures thereof in the presence of polyethers.

Also suitable as polyols for the preparation of component A are polyester polyols with a molecular weight of from about 200 to about 10,000. For example, the reaction of low molecular weight alcohols, especially ethylene glycol, diethylene glycol, neopentyl glycol, hexanediol, butanediol, propylene glycol, glycerol or trimethylolpropane, with caprolactone The obtained polyester polyol. For the preparation of polyester polyols, suitable polyfunctional alcohols are also 1,4-hydroxymethylcyclohexane, 2-methyl-1,3-propanediol, 1,2,4-butanetriol, triethylene Glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, dibutylene glycol, and polytetramethylene glycol.

Other suitable polyester polyols can be prepared by polycondensation. Difunctional and/or trifunctional alcohols are condensed with deficient amounts of dicarboxylic and/or tricarboxylic acids or their reactive derivatives to form polyester polyols. Suitable dicarboxylic acids are e.g. succinic acid and its higher homologues, unsaturated dicarboxylic acids which may have up to 16 C atoms, such as dicarboxylic acids and also e.g. maleic or fumaric acid, Aromatic dicarboxylic acids, in particular isomeric phthalic acids, such as phthalic acid, isophthalic acid or terephthalic acid. Suitable tricarboxylic acids are, for example, citric acid or trimellitic acid. Particularly suitable within the scope of the invention are polyester polyols obtained by the action of at least one of the aforementioned dicarboxylic acids and glycerol, which have residual OH groups. Particularly suitable alcohols are hexylene glycol, ethylene glycol, diethylene glycol or neopentyl glycol or mixtures of 2 or more thereof. Particularly suitable acids are isophthalic acid or adipic acid or mixtures thereof.

In a particularly preferred embodiment of the invention, the polyols added as the polyol component for the preparation of component A are, for example, dipropylene glycol and/or polypropylene glycol and polyester polyols having a molecular weight of from about 400 to about 2,500, Polymers obtained by polycondensation of hexanediol, ethylene glycol, diethylene glycol or neopentyl glycol or mixtures of two or more of these compounds and isophthalic acid or adipic acid or mixtures thereof are preferred. ester polyols.

High molecular weight polyester polyols include, for example, reaction products of polyfunctional alcohols, preferably difunctional alcohols (optionally with minor amounts of trifunctional alcohols), and polyfunctional carboxylic acids, preferably difunctional carboxylic acids. Instead of the free polycarboxylic acids it is also possible (if possible) to add the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of alcohols with preferably 1 to 3 C atoms. The polycarboxylic acid can be aliphatic, cycloaliphatic, aromatic and/or heterocyclic or both. They may be optionally substituted with, for example, alkyl, alkenyl, ether or halogen. Suitable polycarboxylic acids are, for example, succinic acid, hexanediol, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, terephthalic acid, trimellitic acid, phthalic anhydride, Tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylene tetrahydrophthalic anhydride, glutaric anhydride, maleic acid, maleic di Acid anhydride, fumaric acid, dimer fatty acid or trimer fatty acid or a mixture of two or more of the above compounds. Lower amounts of monofunctional fatty acids may optionally be present in the reaction mixture.

The polyester may optionally contain a small portion of terminal carboxyl groups. It is likewise possible to add polyesters obtained by reacting lactones, such as ε-caprolactone, with hydroxyhydroxyacids, such as ω-hydroxycaproic acid.

Polyacetals are likewise suitable as polyol components. Polyacetals are understood to mean compounds obtained by reacting ethylene glycol, such as diethylene glycol or hexanediol or mixtures thereof, with formaldehyde. The polyacetals which can be added within the scope of the invention are likewise obtainable by polymerization of cyclic acetals.

Furthermore, polycarbonates are also suitable as polyols for the preparation of component A. It can be passed through diols, such as propylene glycol, 1,4-butanediol or 1,6-hexanediol, diethylene glycol, triethylene glycol or tetraethylene glycol or composed of 2 or more of the above alcohols Mixtures obtained by reacting with diaryl carbonates such as diphenyl carbonate or phosgene.

Likewise suitable as polyol component for the preparation of component A are polyacrylates with OH groups. Polyacrylates are obtainable, for example, by polymerization of ethylenically unsaturated monomers bearing 1 OH group. The monomers are obtainable, for example, by esterification of ethylenically unsaturated carboxylic acids and difunctional alcohols, generally in a slight excess of alcohol. Suitable ethylenically unsaturated carboxylic acids are, for example, acrylic acid, methacrylic acid, 2-butenoic acid or maleic acid. The corresponding esters with OH groups are such as 2-carboxyethyl acrylate, 2-carboxyethyl methacrylate, 2-hydroxypropyl acrylate, 2-carboxypropyl methacrylate, 3-carboxy acrylate Propyl ester or 3-carboxypropyl methacrylate or mixtures of 2 or more of the above esters.

To prepare component A, the corresponding polyol component is reacted with an at least difunctional isocyanate. Suitable at least difunctional diisocyanates for the preparation of component A essentially carry at least 2 isocyanate groups per isocyanate and generally also preferably carry 2 to 4 isocyanate groups within the scope of the present invention group, more preferably a compound with 2 isocyanate groups.

At least difunctional isocyanates are described below, which are all suitable as at least difunctional isocyanates in the preparation of component A.

These at least difunctional isocyanates are, for example, ethylene diisocyanate, 1,4-butanediisocyanate, 1,6-hexamethylene diisocyanate (HDI), cyclobutane-1,3-diisocyanate, cyclohexane-1, 3- and -1,4-diisocyanates and mixtures of 2 or more of the above compounds, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophor ketone diisocyanate, IPDI), 2,4- and 2,6-hexahydrotoluene diisocyanate, tetramethylxylylene diisocyanate (TMXDI), 1,3- and 1,4-phenylene diisocyanate , 2,4- or 2,6-toluene diisocyanate, diphenylmethane-2,4'-diisocyanate, diphenylmethane-2,2'-diisocyanate, diphenylmethane-4,4' - Diisocyanates or mixtures of 2 or more of the abovementioned diisocyanates.

Likewise suitable as isocyanates in the present invention for the preparation of component A are trifunctional isocyanates or higher isocyanates, such as are obtained by oligomerization of diisocyanates. Examples of these trifunctional and higher polyisocyanates are HDI triisocyanate or IPDI triisocyanate or mixtures thereof or mixed triisocyanates thereof.

In a preferred embodiment of the invention, diisocyanates having 2 isocyanate groups of different reactivity are used for the preparation of component A. Examples of such diisocyanates are 2,4- and 2,6-tolylene diisocyanate (TDI) and isophorone diisocyanate (IPDI). In the case of such asymmetric diisocyanates, generally one isocyanate group reacts very rapidly with isocyanate-reactive groups bearing eg OH groups, while the remaining isocyanate groups are relatively inert. In a preferred embodiment of the invention, the one monocyclic asymmetric diisocyanate used for the preparation of component A contains two of the abovementioned diisocyanate groups of different reactivity.

In a particularly preferred embodiment, 2,4- or 2,6-toluene diisocyanate (TDI) or a mixture of the two isomers, in particular pure 2,4-TDI, is used for the preparation of component A .

The polyurethane adhesives according to the invention contain, as component B, at least difunctional isocyanates which do not contain N atoms other than NCO moieties, or mixtures of two or more of these compounds.

Component B can be formed, for example, by an isocyanate having at least two functional groups or a mixture of 2 or more isocyanates having at least on average about 2 functional groups.

In a preferred embodiment of the invention, component B contains at least one isocyanate having at least two functional groups, the NCO groups on the isocyanate are compatible with the low-reactivity isocyanate groups on the polyurethane prepolymer contained in component A It is more reactive towards reactive NCO groups than, for example, in urethane, thiourethane or allophanation reactions.

The isocyanate groups of the difunctional isocyanates contained in component B may have different reactivity or substantially the same reactivity. In a preferred embodiment of the invention, at least difunctional isocyanates, whose isocyanate groups have the same reactivity, can also be used as component B.

Generally, the molecular weight of component B can be up to about 2000. Somewhat lower molecular weights are preferred, such as less than about 1000, less than about 700 or less than about 400 g/mol.

Suitable additions as component B within the scope of the present invention are 4,4'-diphenylmethane diisocyanate (MDI), 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane Diisocyanates and HDI, IPDI or TMXDI.

In a preferred embodiment, 4,4'-diphenylmethane diisocyanate (MDI), 2,2'-diphenylmethane diisocyanate or 2,4'-diphenylmethane diisocyanate is added.

The polyurethane adhesive according to the invention contains at least about 3% by weight of component B, relative to the total polyurethane adhesive. In a preferred embodiment, the polyurethane adhesive contains from about 5% to about 25% by weight of Component B.

The polyurethane adhesive according to the invention preferably has less than 2% by weight or less than 1% by weight or preferably less than 0.5% by weight of volatile monomers bearing isocyanate groups. These limits are especially applicable to some volatile isocyanate compounds, because such content of the compound has less ability to damage the personnel engaged in the preparation of the compound, such as isophorone diisocyanate, hexamethylene diisocyanate (HDI), tetramethyl For xylylene diisocyanate (TMXDI) or cyclohexane diisocyanate. For certain volatile isocyanate compounds, their content in the polyurethane adhesive according to the invention is preferably less than 0.3% by weight, more preferably less than 0.1% by weight, according to their degree of damage to the preparation personnel. In particular, toluene diisocyanate (TDI) belongs to the last listed isocyanate compounds. In another preferred embodiment of the invention, the polyurethane adhesive has a TDI and HDI content of less than 0.05% by weight.

The polyurethane adhesives according to the invention contain, as component C, one isocyanate having at least two functional groups or two or more isocyanates having an average of at least two functional groups, each of which has at least one non-NCO group moiety or the N atom of a urethane moiety.

Therefore, what is suitable to be added to component C is the carbodiimide with NCO group obtained by the reaction of diisocyanate under suitable conditions and catalyst.

Isocyanates suitable for the formation of carbodiimides are, for example, compounds having the general structure O=C=N-X-N=C=O, where X is an aliphatic, cycloaliphatic or aromatic group, preferably Aliphatic or cycloaliphatic radicals having 4 to 18 C atoms.

Suitable isocyanates are, for example, 1,5-naphthalene diisocyanate, 4,4'-diphenylmethane diisocyanate (MDI), hydrogenated MDI (H ₁₂ MDI), xylylene diisocyanate (XDI), tetramethyl Xylylene diisocyanate (TMXDI), 4,4'-diphenyldimethylmethane diisocyanate, dialkylene diphenylmethane diisocyanate or tetraalkylene diphenylmethane diisocyanate, 4, 4′-Dibenzylidene diisocyanate, 1,3-phenylene diisocyanate, 1,4-phenylene diisocyanate, isomers of tolylene diisocyanate (TDI), 1-methyl-2,4 -Diisocyanate-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′-diisocyanate Phenylperfluoroethane, tetramethoxybutane-1,4-diisocyanate, butane-1,4-diisocyanate, hexane-1,6-diisocyanate (HDI), dicyclohexylmethane diisocyanate , cyclohexane-1,4-diisocyanate, 1,2-ethylene diisocyanate, phthalic acid-diisocyanatoethyl ester. Other diisocyanates containing reactive halogen atoms, such as 1-chloromethylphenyl-2,4-diisocyanate, 1-bromomethylphenyl-2,6-diisocyanate, 3,3-bis- Chloromethyl ether-4,4'-diphenyl diisocyanate.

Other diisocyanates which can be added are, for example, trimethylhexamethylene-diisocyanate, 1,4-diisocyanatobutane, 1,12-diisocyanatododecane and dimerized fatty acid diisocyanate. Particularly suitable are: tetramethylene-, hexamethylene-, undecane-, dodecylmethylene-, 2,2,4-trimethylhexane, 1,3-cyclohexane Alkane-, 1,4-cyclohexane-, 1,3- or 1,4-tetramethyl mixed xylene-, isophorone-, 4,4-dicyclohexyl-methane- and lysine esters - diisocyanates.

Particularly suitable so far for the formation of carbodiimides are the reaction products of MDI, TDI, HDI or IPDI or mixtures of 2 or more of these compounds.

Also suitable are trimers and oligomers of polyisocyanates, which are obtained by suitable reaction of polyisocyanates with formation of isocyanuric rings, diisocyanates being preferred here. If oligomers are added, oligomers having a low degree of polymerization averaging from about 3 to about 5 are particularly suitable.

Isocyanates suitable for the reaction are the diisocyanates already mentioned above, more preferably trimers of polyisocyanates in HDI, MDI or IPDI here.

Also suitable to be added as component C are polymeric isocyanates which, during the distillation of the diisocyanates, are the bottom residue of the distillation column. "Polymeric MDI" which is obtainable from distillation residues of MDI; which has at least 1 N atom which is not an NCO or urethane moiety per 1 isocyanate molecule is particularly suitable.

Component C is added in the polyurethane adhesive according to the invention in an amount of about 1% by weight to about 40% by weight of component C in the total polyurethane adhesive. In a preferred embodiment of the present invention, the polyurethane binder is present in an amount of about 5% to about 30% by weight and more preferably about 10% to about 22% by weight of Component C.

The polyurethane adhesives with the advantages according to the invention can be produced in principle in any manner. However, two methods have proved to be of particular advantage, and are described below:

For example, polyurethane adhesives can be prepared directly by preparing component A, followed by sequential or simultaneous addition of components B and C. Component B can optionally also be added together with other polyol components, if desired.

The present invention therefore also relates to a process for the preparation of polyurethane adhesives with isocyanate groups, which comprises at least 3 stages, wherein:

h) in a first stage, a polyurethane-prepolymer is prepared from at least one difunctional isocyanate and at least one polyol component, and

i) in the second stage, another at least difunctional isocyanate containing no N atoms other than NCO moieties or a mixture of two or more thereof is added,

j) In stage 3, one at least difunctional isocyanate or a mixture of two or more isocyanates with an average of at least two functional groups is added, wherein at least one isocyanate has at least one The N atom of the non-NCO group part, the majority of isocyanate groups present after the end of the first stage, compared with the isocyanate groups of at least difunctional isocyanates added in the second stage, are more sensitive to reactive isocyanates, especially OH base, with low reactivity.

In principle, the polyols listed in the present invention can all be added as further polyols.

In an embodiment of the invention, it is beneficial for the first stage of the process to have an OH:NCO of less than 1:1. In a preferred embodiment the stage 1 OH groups:isocyanate groups ranges from about 0.4 to about 0.7:1, more preferably the ratio is greater than 0.5 to about 0.7:1.

In the first stage, the reaction of the polyol component with the at least difunctional isocyanate can be carried out in any manner familiar to the expert according to the general rules for the preparation of polyurethanes. For example, the reaction can be carried out with a solvent. All solvents commonly used in polyurethane chemistry can be used as solvents. Especially esters, ketones, halogenated hydrocarbon compounds, paraffins, alkenes and aromatic compounds. Examples of such solvents are methylene chloride, trichloroethylene, toluene, xylene, butyl acetate, amyl acetate, isobutyl acetate, methyl isobutyl ketone, methoxybutyl acetate, cyclohexane, Cyclohexenone, Dichlorobenzene, Diethyl Ketone, Diisobutyl Ketone, Dioxane, Ethyl Acetate, Ethylene Glycol Monobutyl Ether Acetate, Ethylene Glycol Monoethyl Acetate , 2-ethylhexyl acetate, ethylene glycol diacetate, heptane, hexane, isobutyl acetate, isooctane, isopropyl acetate, methyl ethyl ketone, tetrahydrofuran or tetrachloroethylene or 2 of these solvents a mixture of one or more.

If the reaction components themselves are liquid or at least one or more of the reaction components form a solution or a suspension of other non-liquid reaction components, then the use of solvents can be dispensed with. Such solvent-free reactions are preferred within the scope of the present invention.

To carry out stage 1 of the process according to the invention, the polyol, optionally together with a suitable solvent, is mixed in a suitable vessel. Immediately thereafter, with further mixing, the at least difunctional isocyanate is added. The temperature is generally increased in order to accelerate the reaction. The temperature of the reaction mixture is generally controlled at about 40°C to about 80°C. The exothermic reaction warrants an increase in temperature. The temperature of the reaction mixture is maintained at about 70°C to about 110°C, such as at about 85 to about 95°C or preferably at about 75 to about 85°C. If necessary, adjust the temperature by suitable external measures such as heating or cooling.

In certain cases, the usual catalysts used in polyurethane chemistry to accelerate the reaction can be added in order to accelerate the reaction. Preference is given to adding dibutyltin dilaurate, diazabicyclooctane (DABCO). If it is desired to add a catalyst, it is generally added to the reaction mixture in an amount of about 0.005% or about 0.01% to about 0.2% by weight of the total reaction mixture.

The duration of the reaction in the first stage depends on the polyol components charged, the at least difunctional isocyanate used, the reaction temperature and, if necessary, the catalyst present. The total duration of the reaction is generally from about 30 minutes to about 20 hours.

Preferred as at least difunctional isocyanates in stage 1 are isophorone diisocyanate (IPDI), tetramethylxylylene diisocyanate (TMXDI), hydrogenated diphenylmethane diisocyanate (MDIH ₁₂ ) Or tolylene diisocyanate (TDI) or a mixture of 2 or more compounds thereof.

In order to carry out the second stage of the process according to the invention, at least one other isocyanate or a mixture of 2 or more compounds having at least a difunctional group which does not contain N atoms of a non-NCO group moiety is optionally combined with another One polyol component is reacted together in admixture with component A obtained in stage 1. Any polyol from the family of polyols recited in the present invention or a mixture of two or more thereof may be used as a constituent of the optionally present other polyols. In the scope of the second stage of the process according to the invention preferably added as polyol component is polypropylene glycol with a molecular weight of about 400 to about 2500 or at least a high content of ester polyols, particularly preferably mainly aliphatic dicarboxylic acids Polyester polyols or mixtures of these polyols.

The at least difunctional isocyanate containing no N atoms other than NCO moieties as the second stage of the process according to the invention is at least one polyisocyanate in which the isocyanate groups have a higher density than that present in the prepolymer Isocyanate groups with low reactivity have high reactivity. This means that reactive isocyanate groups must still be present in the prepolymer, which originate initially from the at least difunctional isocyanate added for the preparation of prepolymer A. In this connection, the essence of the invention is only that at least a small part, preferably a majority, of the isocyanate groups present in the prepolymer of component A have at least The isocyanate groups of difunctional isocyanates that do not contain N atoms other than NCO moieties are less reactive.

Symmetrical bicyclic aromatic diisocyanates are preferred as further at least difunctional isocyanates which do not contain N atoms other than NCO moieties. Such bicyclic isocyanates include, for example, diisocyanates of the diphenylmethane series, especially 2,2'-diphenylmethane diisocyanate, 2,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate and 4,4'-diphenylmethane diisocyanate Phenylmethane diisocyanate. Among the diisocyanates mentioned above, diphenylmethane diisocyanate, more preferably 4,4'-diphenylmethane diisocyanate, is used as further at least difunctional isocyanate in the second stage of the process according to the invention.

Other isocyanates that do not contain the N atom of non-NCO group part at least have two functional groups, the amount that adds in the 2nd stage, with respect to the total amount of the polyisocyanate that adds in all stages by the method of the present invention, about 1% to about 50% by weight, a preferred amount is about 10% to about 30% by weight, and a more preferred amount is about 15% to about 25% by weight.

In a preferred embodiment, the OH:NCO in the second stage is about 0.2 to about 0.6:1, more preferably up to a maximum of about 0.5:1. It is contemplated that any isocyanate groups from prepolymer A are negligible in the OH:NCO ratio of the components added in stage 2.

Polyurethane adhesives with the advantages of the invention can likewise be produced by mixing the individual components D, E, F and G.

Therefore the present invention also relates to a kind of preparation low viscosity polyurethane adhesive with isocyanate group, it only contains a small amount of volatile monomer with isocyanate group, the method comprises four kinds of components D, E, F and A mixture of G, where:

k) a polyurethane-prepolymer with isocyanate groups as component D, which is obtained by reacting an at least difunctional isocyanate with a polyol component;

1) Another polyurethane-prepolymer with isocyanate groups is used as component E, which is obtained by reacting another isocyanate with at least two functional groups and a polyol component, wherein the isocyanate group and the isocyanate of component D Higher reactivity towards reactive isocyanate groups compared to

m) an at least difunctional isocyanate containing no N atoms other than NCO moieties or a mixture of two or more thereof as component F, and

n) as component G is another at least difunctional isocyanate or a mixture of 2 or more isocyanates having an average of at least 2 functional groups, at least one of which contains at least one moiety other than NCO groups of N atoms, the content of component G is measured as follows: after the end of the mixing process and after all necessary reactions between components D, E, F and G, in the polyurethane adhesive, relative to the polyurethane adhesive The content of component G is at least 5% by weight, preferably at least 10% by weight, based on the total amount of the mixture.

The polyurethane adhesives according to the invention and the polyurethane adhesives produced by the process according to the invention preferably have a viscosity value of less than 5000 mPas (measured with a Brookfield RTDV11 (Thermosell) viscometer, spindle 27, 20 rpm, 50° C.).

Within the scope of the present invention, "all necessary reactions between components D, E, F and G" are understood to mean: the reaction of isocyanate groups with functional groups containing hydrogen atoms capable of reacting with isocyanate groups . For example, when component D or E or D and E contain free OH groups, the reaction between the isocyanate groups of component F and the free OH groups generally occurs after the addition of component F. This reduces the content of component F. Therefore, if reactions to reduce the F component content are expected to occur, the amount of Component F added must take into account that after all these reactions are complete, there will still be a required minimum level of Component F in the polyurethane adhesive.

Within the scope of the process according to the invention, for the preparation of components D and E, the abovementioned polyols and mixtures of two or more of the abovementioned polyols can be added as polyol components. It is more preferred within the context of the process according to the invention to add polyol components which are the particularly suitable polyol components already mentioned for the preparation of component A within the scope of the invention.

As component F, at least bifunctional isocyanate or a mixture of two or more of them without N atoms containing non-NCO group moieties can be added, and their production method can simulate the production method of component B.

As component G, at least difunctional isocyanates or mixtures of 2 or more isocyanates with an average of at least 2 functional groups can be added, where at least one isocyanate has 1 N atom that is part of a non-NCO group , the manufacturing method can simulate the manufacturing method of component C.

The polyurethane adhesives according to the invention and the polyurethane adhesives produced by the process according to the invention are characterized in that they contain a particularly low content of volatile isocyanate-group-bearing monomers of less than 2% by weight or less than 1% by weight , preferably less than 0.5% by weight, most preferably less than about 0.1% by weight. It should be emphasized here in particular that the process according to the invention does not have a separate process step for the separation of volatile diisocyanate components.

Another advantage of the polyurethane adhesives prepared according to the process of the invention is that the adhesives have a viscosity range which is very suitable for processing. More specifically, the polyurethane adhesive prepared according to the method of the present invention has a viscosity of less than 5,000 mPas (measured with a Brookfield RTDV11 (Thermosell) viscometer, spindle 27, 20 rpm, 50° C.).

The polyurethane adhesives according to the invention are suitable for addition to materials or as solutions in organic solvents. Coatings for materials in solvents, as already described above, are particularly suitable for bonding multiple objects.

Therefore the present invention also comprises the application of polyurethane adhesive of the present invention or the application of the polyurethane adhesive prepared according to the method of the present invention, and it can be used for preparing adhesive, especially the adhesive of one-component and two-component, and coating is especially used for Used in paints, colored emulsions, casting resins and molded bodies, for coating of objects and especially for bonding of objects, especially for bonding films and preparing composite film materials.

The polyurethane adhesives according to the invention or the polyurethanes prepared according to the process according to the invention are particularly suitable for bonding plastics and more preferably for laminating plastic films, plastic films metallized with metals or metal oxides and metal foil layers , especially for laminating aluminum foil.

The curing process, ie the crosslinking of the individual polyurethane adhesive molecules by free isocyanate groups, can be carried out without the addition of other compounds such as hardeners, but only by atmospheric moisture. Preference is given to adding polymeric-functional crosslinkers as hardeners, such as amines or more preferably polyfunctional alcohols (two-component systems).

When the products prepared according to the present invention are used to prepare composite films by thermocompression bonding, they show high safety because of the reduced component content of migrateable low-molecular-weight products. Suitable processing temperatures for adhesives prepared in accordance with the present invention are between about 30°C and about 90°C.

The invention also relates to two-component H and L adhesives in which:

o) a polyurethane adhesive with isocyanate groups according to the invention or a polyurethane adhesive with isocyanate groups prepared according to the invention, as component H, and

p) A compound having at least 2 functional groups reactive with the isocyanate groups of component H, with a molecular weight of up to 50,000 or a mixture of two or more of such compounds, as component I.

Thus any of the aforementioned polyurethane adhesives of the invention can be used as component H.

Component I may be preferably a compound having at least 2 functional groups reactive with the isocyanate groups of component F, the molecular weight of which can be up to 2500 or a mixture of 2 or more of these compounds. The functional groups reactive with the isocyanate groups of component F may in particular be selected from amino, sulfhydryl or OH groups. Compounds suitable for use in component G may have amino, sulfhydryl or OH groups, either alone or in mixtures.

Compounds useful in Component I generally have at least about 2 functional groups. Component I has a certain percentage of higher functional compounds, for example with 3, 4 or more functional groups. The number of total functional groups (on average) of component I is, for example, about 2 (for example as only difunctional compounds of component I) or more functional groups, such as about 2.1, 2.2, 2.5, 2.7 or 3 functional groups base. Alternatively, Component I may have a higher number of functional groups, such as about 4 or more.

Component I preferably contains a polyol having at least 2 OH groups. All polyols mentioned in the present invention are suitable for addition to component I, as long as their upper molecular weights comply with the restrictions.

Generally, the amount of component I added is that the ratio of the isocyanate group of component H to the functional group in component I that can react with the isocyanate group of component H is about 5:1 to about 1:1, preferably About 2:1 to about 1:1.

Generally, the viscosity value of the adhesive of the present invention is from about 250 to about 10,000 mPas, preferably from about 500 to about 8,000 or to about 5000 mPas (measured with a Brookfield RVT DV11 viscometer, spindle 27, 20 rpm, 40° C.).

The adhesive according to the invention can also optionally contain additives, which can be added in an amount of up to 30% by weight of the total adhesive.

Additives which may be added within the scope of the invention are, for example, plasticizers, stabilizers, antioxidants, dyes, light stabilizers or fillers.

Added as plasticizers may be e.g. plasticizers based on phthalic acid, especially dialkyl phthalates, preferably esters of linear alkanols having from about 6 to about 12 C atoms Preferred phthalates are used as plasticizers, more preferably dioctyl phthalate.

Also suitable as plasticizers are benzoate plasticizers such as sucrose benzoate, diethylene glycol dibenzoate and/or wherein from about 50% to about 95% of all hydroxyl groups have been esterified Diethylene glycol benzoate; phosphate plasticizers, such as tert-butylphenyl diphenyl phosphate, polyethylene glycol and its derivatives, such as poly(ethylene glycol) diphenyl ether; Liquid resin derivatives, such as hydrogenated resin methyl esters, vegetable and animal oils such as glycerol esters of fatty acids and their polymerization products.

Stabilizers or antioxidants added as additives within the scope of the invention include sterically hindered high molecular weight (Mn) phenols, polyphenols, sulfur-containing phenols and phosphorus-containing phenols. Phenols added as additives within the scope of the present invention are, for example, 1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-butyl-4-hydroxybenzyl)benzene, pentaerythritol Tetrakis-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, n-octadecyl-3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 4 ,4-methylene-bis(2,6-di-tert-butylphenol), 4,4-thiobis(6-tert-butyl-o-cresol), 2,6-di-tert-butylphenol, 6-(4 -Hydroxyphenoxy)-2,4-bis(n-octylthio)-1,3,5-triazine, di-n-octadecyl-3,5-di-tert-butyl-4-hydroxybenzyl phosphonate, 2-(n-octylthio)ethyl-3,5-di-tert-butyl-4-hydroxybenzoate and sorbitol hexa[3-(3,5-di-tert-butyl -4-hydroxyphenyl)propionate].

Suitable as light stabilizer is the commercial product Thinuvin(R) (manufacturer: Ciba Geigy).

Other additives may also be added to the adhesives according to the invention to modify certain properties. These other additives include dyes such as titanium dioxide, fillers such as talc, clays and similar materials. The adhesive of the present invention may also optionally contain a small amount of thermoplastic polymers or copolymers, such as ethylene/vinyl acetate (EVA), ethylene/acrylic acid, ethylene/methacrylate and ethylene/n-butyl acrylate copolymers , and under certain circumstances, these compounds can impart additional flexibility, toughness, and strength to the adhesive. Also can preferably add a certain amount of hydrophilic polymer in the scope of the present invention, as polyvinyl alcohol, hydroxyethyl cellulose, hydroxypropyl cellulose, polyvinyl methyl ether, polyethylene oxide, polyvinylpyrrolidone , polyethyloxazoline or starch or cellulose ester, especially acetate with a degree of substitution of less than 2.5, which improves the wettability of the adhesive.

The invention is discussed below by means of some examples, but they are not limiting.

Example:

Notes on raw materials and abbreviated names in Table 1

K1-K5: Adhesive formulations 1 to 5

H: hardener (polyol mixture), OHZ=138.8

PE1: Polyether based on propylene glycol

PE2: Polyether based on propylene glycol

DEG: diethylene glycol

PES: polyester based on adipic acid, diethylene glycol, phthalic acid and dipropylene glycol with 2 OH groups

PE3: Polyether based on propylene glycol

MDI-C: MDI-carbodiimide dimer

HDI-T: HDI-Trimer

HDI-O: HDI-Oligomer

MDI-P: Polymer MDI (lower residue from distillation column)

ADV-1: OH/NCO polymerization ratio of component A and component B

ADV-G: total OH/NCO polymerization ratio

V: Viscosity (Viscometer Brookfield, RVTD, 40°C)

MC: monomer content, % by weight (for the total amount of formula)

m-TDI: Monomer TDI

m-MDI: monomeric MDI

OHZ: OH number (mg KOH/g)

NCO value: NCO content-% by weight (for the total amount of formula)

NCO-F: NCO final value

Table 1 Adhesive formula (if no special unit is marked on the numerical value, all component contents are by weight %) raw material OHZ or NCO value K1 K2 K3 K4 K5 h PE1 111 29.4 29.4 29.4 29.4 29.4 PE2 267 9.8 9.8 9.8 9.8 9.8 DEG 1056 4.9 4.9 4.9 4.9 4.9 1.8 PES 108 93.0 PE3 373 5.2 TDI 48.3 25.6 24.9 24.9 24.9 24.9 MDI 33.4 30.9 20.0 20.0 20.0 20.0 MDI-C 33 13.1 HDI-T twenty one 20.6 HDI-O 21.9 19.8 MDI-P 31 14.0 NCO-F 14.0 13.5 13.3 13.1 14.3 ADV-1 1.6 1.6 1.6 1.6 1.6 ADV-G 2.76 2.76 2.76 2.76 2.76 V[mPas] 40℃ 2700 4450 6000 5300 4320 50℃ 1200 1800 2550 1970 1790 60℃ 550 956 1200 950 790 m-TDI 0.03 0.03 0.07 0.07 0.09 m-MDI 30 twenty four 16 14 20

Explanation of abbreviated names in Table 2

B1-8: Examples 1-8

V1-2: Comparative Examples 1 and 2

VA: laminated structure

F1: A film made of polyethylene terephthalate (PETP) with a thickness of 12μ

F2: A film made of polyethylene (PE), which contains 400ppm of plasticizer-erucamide (ESA), and its thickness is 70μ

F3: A film made of polyethylene (PE), which contains 800ppm of plasticizer-erucamide (ESA), and its thickness is 60μ

(ESA)VH: Composite Bonding

SNH: Bonding at glued seams

koh.KS: Cohesive Cracking of Adhesives

adh.alt.: Adhesive cracking alternates on both sides of the composite when changing the bond

The mixing ratio of ingredients/hardener in the adhesive is 1:1 in the formulations of B1-B8, and 100:70 in the formulations of V1 and V2.

In all examples, the amount applied was 2 g/m ² .

Table 2: Adhesive Statistics Composite structure Adhesive system Composite adhesion after 1 day (VH), N/15mm Composite adhesion after 6 days (VH), N/15mm Composite adhesion after curing (VM), N/15mm Adhesion at the glued seam after curing (SNA), N/15mm B1 F1/F2 K2/H 1.8koh.KS 3.3 PETP-fracture 3.3 PETP-fracture 43VA B2 F1/F2 K3/H 0.2koh.KS 2.2 Adhesive separation adh.alt. 3.2 PETP-fracture 42VA B3 F1/F2 K4/H 0.2koh.KS 3.3 PETP-fracture 3.3 PETP-fracture 43VA B4 F1/F2 K5/H 0.25koh.KS 3.6 PETP-fracture 3.4 PETP-fracture 44VA V1 F1/F2 K1/H 3.2 PETP-fracture 3.5 PETP-fracture 3.3 PETP-fracture 43VA B5 F1/F3 K2/H 0.6koh.KS 2.9 PETP-fracture 3.4 PETP-fracture 36VA B6 F1/F3 K3/H 0.1koh.KS 1.8 Adhesive separation adh.alt. 3.6 PETP-fracture 35VA B7 F1/F3 K4/H ＜0.1koh.KS 1.6 Adhesive separation adh.alt. 3.2 PETP-fracture 34VA B8 F1/F3 K5/H 0.5koh.KS 3.2 PETP-fracture 3.4 PETP-fracture 34VA V2 F1/F3 K1/H 1.0koh.KS 1.6 Adhesive separation adh.alt. 1.6 Adhesive separation adh.alt. 23, PETP-break at the edge of the adhesive seam

Claims (21)

1. A polyurethane adhesive containing a small amount of volatile monomers with isocyanate functional groups, the adhesive contains at least three components A, B and C, wherein: a) Contains as component A a polyurethane polymer with at least 2 isocyanate groups or a mixture of 2 or more polyurethane-prepolymers with at least 2 isocyanate groups, in which at least one polyurethane- Prepolymers with at least 2 different isocyanate bonded forms or 2 different polyurethane-prepolymers in pairs with at least 2 different isocyanate bonded forms, of which at least one isocyanate bonded form is combined with the other isocyanate groups It has lower reactivity towards reactive isocyanates than the conjugated form, and b) as component B, one or a mixture of two or more isocyanates containing at least two functional groups and not containing N atoms other than NCO moieties, and c) Containing, as component C, one isocyanate having at least two functional groups or a mixture of two or more isocyanates having an average of at least two functional groups, wherein each isocyanate molecule has at least one non-NCO group or the N atom of a part of the urethane group. 2. 2. Polyurethane adhesive according to claim 1, characterized in that component C is at least 5% by weight relative to the total polyurethane adhesive. 3. 2. Polyurethane adhesive according to claim 1 or 2, characterized in that the content of volatile monomers carrying isocyanate groups is less than 1% by weight, wherein the content of toluene diisocyanate (TDI) is less than 0.1% by weight. 4. Polyurethane adhesive according to any one of claims 1 to 3, characterized in that component A is prepared by 1 reaction with at least 2 stages, wherein: d) In the first stage, a polyurethane-prepolymer is prepared from one isocyanate having at least two functional groups and at least one first polyol component, wherein the NCO/OH ratio is less than 2 and in the polyurethane-prepolymer There are also free OH groups present in the compound, and e) In stage 2, another at least difunctional isocyanate is reacted with the polyurethane-prepolymer from stage 1, wherein the isocyanate groups of the isocyanate added in stage 2 react with the polyurethane of stage 1 - It is more reactive towards reactive isocyanate compounds than the major part of the isocyanate groups present in the prepolymer. 5. The polyurethane adhesive according to claim 4, characterized in that, relative to the free OH groups of component A, a molar excess of other at least difunctional isocyanates is added. 6. Polyurethane adhesive according to any one of claims 1 to 3, characterized in that component A is prepared by a reaction of at least 2 stages, wherein: f) In the first stage, a polyurethane-prepolymer is prepared from one isocyanate having at least two functional groups and at least one first polyol component, wherein the NCO/OH ratio is less than 2 and in the polyurethane-prepolymer There are also free OH radicals present in the substance, and g) In a second stage, another at least difunctional isocyanate and another polyol component are reacted with the polyurethane-prepolymer from the first stage, wherein the isocyanate added in the second stage The isocyanate groups are more reactive towards reactive isocyanate compounds than the major part of the isocyanate groups present in the polyurethane prepolymer of the first stage. 7. The polyurethane adhesive according to claim 6, characterized in that other at least difunctional isocyanates are added in molar excess relative to the OH groups of component A and the other polyol components. 8. 2. Polyurethane adhesive according to any one of claims 4 to 7, characterized in that the OH:NCO ratio in the second stage is between 0.1:1 and 1:1, preferably 0.2:1 to 0.6:1. 9. 2. Polyurethane adhesive according to any one of claims 4 to 8, characterized in that the OH:NCO ratio in the first stage is less than 1:1, preferably between 0.5:1 and 0.7:1. 10. A method for preparing a polyurethane adhesive with isocyanate groups, comprising at least three stages, wherein: h) in a first stage, a polyurethane-prepolymer is prepared from at least one difunctional isocyanate and at least one polyol component, i) in stage 2, adding 1 other at least difunctional isocyanate or 1 other at least difunctional isocyanate and 1 further polyol component, and j) In stage 3, one isocyanate having at least two functional groups or a mixture of two or more isocyanates having an average of at least two functional groups is added, wherein at least one isocyanate contains at least one non-NCO Compared with the isocyanate groups with at least difunctional isocyanate added in the second stage, the majority of isocyanate groups present after the end of the first stage have a higher resistance to reactive isocyanates, especially OH groups. low reactivity. 11. Process according to claim 10, characterized in that the OH:NCO ratio in the second stage is 0.2:1 to 0.6:1. 12. Process according to claim 10 or 11, characterized in that in the first stage OH:NCO is less than 1:1, preferably 0.4:1 to 0.7:1. 13. According to the preparation method of any one of claims 10 to 12, it is characterized in that isophorone diisocyanate (IPDI), tetramethylxylylene diisocyanate (TMXDI), hydrogenated diphenylmethane diisocyanate ( MDI _H12 ) or tolylene diisocyanate (TDI) as at least difunctional isocyanate in the first stage. 14. Process according to any one of claims 10 to 13, characterized in that, in the second stage, diphenylmethane diisocyanate (MDI) is used as the other at least difunctional isocyanate. 15. A method for preparing a low-viscosity polyurethane adhesive containing isocyanate groups and containing a small amount of volatile monomers with isocyanate groups, the method comprises mixing D, E, F and G4 kinds of components, wherein: k) obtaining isocyanate-functional polyurethane prepolymers as component D by reacting an at least difunctional isocyanate with a polyol component, 1) Obtain a kind of other polyurethane-prepolymer with isocyanate groups as component E by reacting a kind of other at least difunctional isocyanate with a polyol component, wherein the isocyanate in component E group is more reactive towards reactive isocyanate groups than the isocyanate groups of component D, m) an at least difunctional isocyanate containing no N atoms other than NCO moieties or a mixture of two or more such isocyanates as component F, and n) as component G a further at least difunctional isocyanate or a mixture of 2 or more isocyanates with an average of at least 2 functional groups, of which at least one isocyanate contains at least one non- The N atom of the NCO base moiety, The content of component G was determined as follows: after the mixing process and after all necessary reactions between components D, E, F and G, in the polyurethane adhesive relative to the total In terms of quantity, the content of component G is at least 5% by weight, preferably at least 10% by weight. 16. According to the preparation method of any one of claims 10 to 15, it is characterized in that the viscosity of the polyurethane adhesive is less than 5000mPas (measure viscosity with viscometer Brookfield RTDV11 (Thermosell), rotating shaft 27, 20 rev/min, 50 ℃) . 17. According to the polyurethane adhesive of any claim in claims 1 to 9 or the application of the polyurethane adhesive prepared by the method of any claim in claims 10 to 16, it can be applied to the preparation of adhesives, especially containing single Preparation of one- and two-component adhesives, coatings, especially paints, colored emulsions, casting resins, preparation of molded bodies, for coatings, especially for object gluing, especially for film gluing and for the production of films composite material. 18. Adhesives containing components H and I, wherein: o) a polyurethane adhesive containing isocyanate groups according to any one of claims 1 to 9 or a polyurethane adhesive having isocyanate groups prepared according to any one of claims 10 to 16 as component H, and p) as component I compounds having a molecular weight of up to 50,000 which contain at least 2 functional groups which are reactive with the isocyanate groups of component F or mixtures of 2 or more such compounds. 19. Adhesive according to claim 18, characterized in that as component I a polyol having at least 2 OH groups. 20. Adhesive according to claim 18 or 19, characterized in that component I is used in an amount such that the ratio of the isocyanate groups of component H to the functional groups reacting with the isocyanate groups of component H in component I is 5:1 to 1: 1, preferably 2:1 to 1:1. twenty one. 6. Adhesive according to any one of claims 18 to 20, characterized in that it has a viscosity value of 500 to 6500 mPas (viscometer Brookfield, RVTD, 40° C.).