DE102010043486A1 - Binding flat, flexible substrates to non-flexible substrates, comprises applying an adhesive to flexible substrate and adhering flexible substrate coated with adhesive to non-flexible substrate, where adhesive contains carbodiimide groups - Google Patents

Abstract

Binding flat, flexible substrates to non-flexible substrates comprises applying an adhesive to the flexible substrate, and adhering the flexible substrate coated with adhesive to the non-flexible substrate, where the adhesive used for the binding contains 0.0001-0.1 mole of carbodiimide groups for 100 g of adhesive, calculated on a solvent-free adhesive, where the compounds of the adhesive, exhibiting carbodiimide groups, contains urea groups, and this urea groups are prepared by hydrolysis of isocyanate groups containing carbodiimide compounds. Binding flat, flexible substrates to non-flexible substrates, comprises applying an adhesive to the flexible substrate, and adhering the flexible substrate coated with adhesive to the non-flexible substrate, where the adhesive used for the binding contains 0.0001-0.1 mole of carbodiimide groups for 100 g of adhesive, calculated on a solvent-free adhesive, where the compounds of the adhesive, exhibiting carbodiimide groups, contains urea groups, and this urea groups are prepared by hydrolysis of isocyanate groups containing carbodiimide compounds or by reaction of isocyanate groups containing carbodiimide compounds with non-polymer, acid group-free amine compounds. Independent claims are included for: (1) a non-flexible substrate coated with flat, flexible substrates, obtained by the above process; and (2) flexible substrates made of at least one flexible support and an adhesive coating.

Description

The invention relates to a method for bonding flat, flexible substrates with non-flexible substrates (laminating method), wherein an adhesive is applied to the flexible substrate and the adhesive coated flexible substrate is bonded to the non-flexible substrate. The adhesive used for the bonding has carbodiimide groups and the carbodiimide group-containing compounds of the adhesive have urea groups which can be prepared from isocyanate-containing carbodiimide compounds either by hydrolysis or by reaction with non-polymeric, acid group-free amine compounds. The invention also relates to flexible substrates which can be used for the laminating process and coated with a corresponding adhesive.

In the automotive and furniture industry components are often laminated with a plastic film. In this case, the substrate and / or the film to be laminated is coated with an adhesive from the production of the laminated component and, optionally after thermal activation of the adhesive, the two adherends are glued together, generally under application of pressure. It would be advantageous if the coating of the laminating film could not be made by the manufacturer of the laminated component, but by the manufacturer of the laminating film, since the film manufacturer anyway performs a pretreatment step, z. B. the film coated with adhesion promoter. The method of adhesive application in a continuous process such as the roller or roller application also offers the advantage of avoiding the so-called overspray when applying adhesive to the component to be laminated. As an adhesive, aqueous polymer dispersions are often used. It is also common practice to add a crosslinker to the dispersion to ensure sufficient heat resistance of the adhesive bond. As crosslinkers, isocyanates are frequently used, but because of their short life, which generally does not exceed one working day, the adhesive dispersion can be added shortly before use. Even in the dry adhesive coating occurs after a short time a reaction of the crosslinking agent, so that no storable coated with adhesive laminating films can be produced.

From the DE 10330748 A1 a method for bonding flat substrates is known. Carbodiimides are used as crosslinkers. While this method provides bonds having good properties, it is desirable to further extend the shelf life of the coated film.

Object of the present invention was a method for bonding flexible substrates, eg. As polymer films, with non-flexible substrates, (laminating) in which the already coated flexible substrates can be stored particularly long and which are obtained in the subsequent bonding composites with high strength and durability, especially high heat resistance.

It has been found that adhesives containing compounds which have carbodiimide groups and additionally urea groups have a delayed crosslinking. The adhesives obtained in this way are particularly suitable for the production of laminating films precoated with these adhesives and having a particularly long shelf life.

The invention relates to a method for bonding flat, flexible substrates with non-flexible substrates, wherein an adhesive is applied to the flexible substrate and the adhesive-coated flexible substrate is bonded to the non-flexible substrate, wherein the adhesive used for the bonding 0 , 0001 to 0.1 mol of carbodiimide groups per 100 g of adhesive, calculated on solvent-free adhesive, and wherein the carbodiimide group-containing compounds of the adhesive have urea groups and these urea groups can be prepared by hydrolysis of isocyanate-containing carbodiimide compounds or by reacting isocyanate-containing carbodiimide compounds with non-carb polymeric, acid group-free amine compounds.

The adhesive used in the process of the present invention contains from 0.0001 to 0.1 mole, preferably from 0.0005 to 0.1 mole, more preferably from 0.001 to 0.1 mole of carbodiimide groups per 100 grams of adhesive, calculated on solvent-free adhesive, ie. H. Water or organic solvents with a boiling point below 150 ° C at 1 bar are not included in the weight of the adhesive. In particular, the content of carbodiimide groups is not higher than 0.05 mol / 100 g of adhesive.

Carbodiimide groups have the general structural formula -N = C = N-. Suitable compounds with carbodiimide groups generally contain on average 1 to 20, preferably 1 to 15, particularly preferably 2 to 10 carbodiimide groups.

Carbodiimide groups are readily available from two isocyanate groups with elimination of carbon dioxide: -RN = C = O + O = C = NR-RN = C = NR- + CO ₂

Starting from polyisocyanates or diisocyanates, carbodiimides having a plurality of carbodiimide groups and optionally isocyanate groups, in particular terminal isocyanate groups, are thus obtainable.

Suitable diisocyanates z. B. Diisocyanates X (NCO) ₂ , wherein X is an aliphatic hydrocarbon radical having 4 to 12 carbon atoms, a cycloaliphatic or aromatic hydrocarbon radical having 6 to 15 carbon atoms or an araliphatic hydrocarbon radical having 7 to 15 carbon atoms. Examples of such diisocyanates are tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,5,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), 2,2-bis (4-isocyanatocyclohexyl) propane, trimethylhexane diisocyanate, 1,4-diisocyanatobenzene, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanato-diphenylmethane, 2,4'-diisocyanato-diphenylmethane, p-xylylene diisocyanate, tetramethylxylylene diisocyanate (TMXDI), the isomers of the bis- (4-isocyanatocyclohexyl) methane (HMDI) as the trans / trans, the cis / cis and the cis / trans isomers and mixtures consisting of these compounds. Particularly preferred are TMXDI and IPDI.

The carbodiimide group-containing compounds of the adhesive still have urea groups in addition to the carbodiimide groups. The amount of urea groups is preferably greater than 0.01 mol per 100 g of carbodiimide-containing compounds, more preferably from 0.01 to 1 mol per 100 g of carbodiimide-containing compounds.

The urea groups may be introduced into the carbodiimide compounds, for example, by hydrolysis of carbodiimide compounds containing isocyanate groups. For this purpose, isocyanate-group-containing carbodiimide compounds emulsified in water and so long, optionally at elevated temperature, for. B. stirred at 20 to 100 ° C until no more NCO groups are detectable. Preferably, they are linear carbodiimide compounds having terminal isocyanate groups.

The urea groups can also be introduced into the carbodiimide compounds by reaction of carbodiimide compounds containing isocyanate groups with non-polymeric, acid group-free amine compounds. Preferably, they are linear carbodiimide compounds having terminal isocyanate groups.

Suitable non-polymeric, acid group-free amine compounds are amines having at least one NH and / or one NH ₂ group. Particularly preferred amines are monoamines, such as monoalkylamines H ₂ N-R 1 or dialkylamines HN-R 1 R 2, where the alkyl radicals R 1 and R ₂ may be identical or different and have 1 to 18 C atoms. Further particularly preferred amines are diaminoalkanes H ₂ N-R 3 -NH ₂ , where R 3 is alkylene radicals having ₂ to 18 C atoms. Further particularly preferred amines are triaminoalkanes H ₂ N-R 4 -NH-R 5 -NH ₂ , where R 4 and R 5 are alkylene radicals which may be identical or different and have 2 to 18 C atoms. Also, aromatic amines in which the amino group is not directly attached to the aromatic group can be used. Aromatic amines in which the amino group is bonded directly to the aromatic group may also be used, but are less preferred.

In a preferred embodiment, the urea-containing carbodiimide compounds are obtained by hydrolysis of carbodiimide compounds containing isocyanate groups.

The adhesive used in the invention, the carbodiimides z. B. as an additive or in bound form, for. B. by attachment to a polyurethane or a free-radically polymerized polymer.

The adhesive to be used according to the invention preferably contains further reactive groups which can undergo a crosslinking reaction with one another or with the carbodiimide groups. In consideration come z. B. carboxyl or carboxylate groups. These reactive groups are preferably present in an amount of from 0.0001 to 0.5 mol, more preferably from 0.0005 to 0.5 mol / 100 g of adhesive. Carboxyl groups are also formed by saponification reactions, so that crosslinking occurs even without an initial content of carboxyl groups in the polyurethane.

The adhesive to be used according to the invention consists essentially of at least one polymeric binder and optionally additives such as fillers, thickeners, defoamers, etc. The additives also include the carbodiimides, provided that they are not bound to a polymeric binder. The polymeric binder is preferably present as a solution or dispersion in water or other solvent having a boiling point below 150 ° C (1 bar). Particularly preferred is water. For weight information on the composition of the adhesive, the water or other solvents is not included. The polymeric binder is preferably a polyurethane, a free-radically polymerized polymer or mixtures thereof. In particular, the polymeric binders are in the form of aqueous dispersions.

The polyurethanes preferably consist predominantly of polyisocyanates, in particular diisocyanates on the one hand and as reactants, polyester diols, polyether diols or mixtures thereof on the other hand. Preferably, the polyurethane is at least 40 wt .-%, more preferably at least 60 wt .-% and most preferably at least 80 wt .-% of diisocyanates, polyether diols and / or polyester diols constructed. Preferably, the polyurethane has a softening point or melting point in the range of -50 to 150 ° C, more preferably from 0 to 100, and most preferably from 10 to 90 ° C. More preferably, the polyurethane has a melting point in the above temperature range. For this purpose, the polyurethane preferably contains polyester diols in an amount of more than 10% by weight, based on the polyurethane.

• a) Diisocyanaten,
• b) Diolen, von denen
• b₁) 10 bis 100 mol-%, bezogen auf die Gesamtmenge der Diole (b), ein Molekulargewicht von 500 bis 5000 g/mol aufweisen,
• b₂) 0 bis 90 mol-%, bezogen auf die Gesamtmenge der Diole (b), ein Molekulargewicht von 60 bis 500 g/mol aufweisen,
• c) von den Monomeren (a) und (b) verschiedene Monomere mit wenigstens einer Isocyanatgruppe oder wenigstens einer gegenüber Isocyanatgruppen reaktiven Gruppe, die darüber hinaus wenigstens eine hydrophile Gruppe oder eine potentiell hydrophile Gruppe tragen, wodurch die Wasserdispergierbarkeit der Polyurethane bewirkt wird,
• d) optional weiteren, von den Monomeren (a) bis (c) verschiedenen mehrwertigen Verbindungen mit reaktiven Gruppen, bei denen es sich um alkoholische Hydroxylgruppen, primäre oder sekundäre Aminogruppen oder Isocyanatgruppen handelt und
• e) optional von den Monomeren (a) bis (d) verschiedenen, einwertigen Verbindungen mit einer reaktiven Gruppe, bei der es sich um eine alkoholische Hydroxylgruppe, eine primäre oder sekundäre Aminogruppe oder eine Isocyanatgruppe handelt.

Overall, the polyurethane is preferably composed of:

• a) diisocyanates,
• b) Diols, of which
• b ₁ ) 10 to 100 mol%, based on the total amount of diols (b), have a molecular weight of 500 to 5000 g / mol,
• b ₂ ) 0 to 90 mol%, based on the total amount of diols (b), have a molecular weight of 60 to 500 g / mol,
• c) monomers other than monomers (a) and (b) having at least one isocyanate group or at least one isocyanate group-reactive group further having at least one hydrophilic group or a potentially hydrophilic group, thereby causing the water dispersibility of the polyurethanes;
• d) optionally further, other than the monomers (a) to (c) polyvalent compounds having reactive groups which are alcoholic hydroxyl groups, primary or secondary amino groups or isocyanate groups, and
• e) optionally from the monomers (a) to (d) different monovalent compounds having a reactive group which is an alcoholic hydroxyl group, a primary or secondary amino group or an isocyanate group.

Particular mention may be made as monomers (a) of diisocyanates X (NCO) ₂ , wherein X is an aliphatic hydrocarbon radical having 4 to 15 carbon atoms, a cycloaliphatic or aromatic hydrocarbon radical having 6 to 15 carbon atoms or an araliphatic hydrocarbon radical having 7 to 15 carbon atoms. Examples of such diisocyanates are tetramethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,5,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), 2,2-bis (4-isocyanatocyclohexyl) propane, trimethylhexane diisocyanate, 1,4-diisocyanatobenzene, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanato-diphenylmethane, 2,4'-diisocyanato-diphenylmethane, p-xylylene diisocyanate, tetramethylxylylene diisocyanate (TMXDI), the isomers of the bis- (4-isocyanatocyclohexyl) methane (HMDI) as the trans / trans, the cis / cis and the cis / trans isomers and mixtures consisting of these compounds. Such diisocyanates are available commercially. Particularly suitable mixtures of these isocyanates are the mixtures of the respective structural isomers of diisocyanatotoluene and diisocyanato-diphenylmethane; in particular, the mixture of 80 mol% of 2,4-diisocyanatotoluene and 20 mol% of 2,6-diisocyanatotoluene is suitable. Furthermore, the mixtures of aromatic isocyanates such as 2,4-diisocyanatotoluene and / or 2,6-diisocyanatotoluene with aliphatic or cycloaliphatic isocyanates such as hexamethylene diisocyanate or IPDI are particularly advantageous, wherein the preferred mixing ratio of aliphatic to aromatic isocyanates 4: 1 to 1: 4 , To build up the polyurethanes can be used as compounds except the aforementioned also isocyanates, in addition to the free isocyanate groups further blocked isocyanate groups, eg. B. wear uretdione groups.

With regard to good film formation and elasticity, suitable diols (b) are primarily relatively high molecular weight diols (b1) which have a molecular weight of about 500 to 5000, preferably about 1000 to 3000 g / mol. This is the number average molecular weight Mn. Mn is determined by determination the number of end groups (OH number). The diols (b1) may be polyester polyols, the z. B. off Ullmanns Enzyklopadie der technischen Chemie, 4th Edition, Volume 19, pp. 62-65 are known. Preference is given to using polyesterpolyols which are obtained by reacting dihydric alcohols with dibasic carboxylic acids. Instead of the free polycarboxylic acids, it is also possible to use the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols or mixtures thereof to prepare the polyesterpolyols. The polycarboxylic acids may be aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic and optionally, for. B. by halogen atoms, substituted and / or unsaturated. Examples of these are: suberic acid, azelaic acid, phthalic acid, isophthalic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylenetetrahydrophthalic anhydride, glutaric anhydride, maleic acid, maleic anhydride, fumaric acid, dimer fatty acids. Preferred are dicarboxylic acids of the general formula HOOC- (CH ₂ ) _y -COOH, where y is a number from 1 to 20, preferably an even number from 2 to 20, z. Succinic acid, adipic acid, sebacic acid and dodecanedicarboxylic acid.

As polyhydric alcohols come z. As ethylene glycol, propane-1,2-diol, propane-1,3-diol, butane-1,3-diol, butene-1,4-diol, butyne-1,4-diol, pentane-1,5- diol, neopentyl glycol, bis (hydroxymethyl) cyclohexanes such as 1,4-bis (hydroxymethyl) cyclohexane, 2-methylpropane-1,3-diol, methylpentanediols, furthermore diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, dibutylene glycol and Polybutylene glycols into consideration. Alcohols of the general formula HO- (CH ₂ ) _x -OH, where x is a number from 1 to 20, preferably an even number from 2 to 20, are preferred. Examples of these are ethylene glycol, butane-1,4-diol, hexane-1,6-diol, octane-1,8-diol and dodecane-1,12-diol. Further preferred is neopentyl glycol.

Furthermore, if appropriate, polycarbonate diols, as they are, for. B. can be obtained by reacting phosgene with an excess of the mentioned as synthesis components for the polyester polyols low molecular weight alcohols into consideration.

Optionally, it is also possible to use polyester-based lactone-based sols, which are homopolymers or copolymers of lactones, preferably hydroxyl-terminated addition products of lactones to suitable difunctional starter molecules. Suitable lactones are preferably those which are derived from compounds of the general formula HO- (CH ₂ ) _z -COOH, where z is a number from 1 to 20 and an H atom of a methylene unit is also denoted by a C ₁ - to C _4- alkyl radical may be substituted. Examples are epsilon-caprolactone, β-propiolactone, gamma-butyrolactone and / or methyl epsilon-caprolactone and mixtures thereof. Suitable starter components are for. As the above-mentioned as a structural component for the polyester polyols low molecular weight dihydric alcohols. The corresponding polymers of epsilon-caprolactone are particularly preferred. Lower polyester diols or polyether diols can also be used as starters for the preparation of the lactone polymers. Instead of the polymers of lactones, it is also possible to use the corresponding, chemically equivalent polycondensates of the hydroxycarboxylic acids corresponding to the lactones.

Polyetherdiols are in particular by polymerization of ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin with itself, z. B. in the presence of BF ₃ or by addition of these compounds, optionally in admixture or in succession, to starting components with reactive hydrogen atoms, such as alcohols or amines, for. For example, water, ethylene glycol, propane-1,2-diol, propane-1,3-diol, 2,2-bis (4-hydroxyphenyl) propane or aniline available. Particularly preferred are polypropylene oxide, polytetrahydrofuran having a molecular weight of 240 to 5000, and especially 500 to 4500 g / mol.

Under b ₁ ) fall only polyether diols, which consist of less than 20 wt .-% of ethylene oxide. Polyether diols containing at least 20% by weight are hydrophilic polyether diols which belong to monomers c).

Optionally, polyhydroxyolefins may also be used, preferably those having 2 terminal hydroxyl groups, for. B. α, -ω-Dihydroxypolybutadien, α, -ω-Dihydroxypolymethacrylester or α, -ω-Dihydroxypolyacrylester as monomers (c1). Such compounds are for example from the EP-A 0622378 known. Further suitable polyols are polyacetals, polysiloxanes and alkyd resins.

At least 95 mol% of the diols b ₁ ) are preferably polyetherdiols. Particular preference is given to using diols b ₁ ) exclusively polyetherdiols.

The hardness and the modulus of elasticity of the polyurethanes can be increased if, as diols (b), in addition to the diols (b ₁ ), low molecular weight diols (b ₂ ) having a molecular weight of about 60 to 500, preferably 62 to 200, g / mol are used become. As monomers (b ₂ ) are mainly the structural components the short-chain alkanediols mentioned for the preparation of polyester polyols are used, preference being given to the unbranched diols having 2 to 12 C atoms and an even number of carbon atoms and also pentane-1,5-diol and neopentyl glycol. As diols b ₂ ) come z. As ethylene glycol, propane-1,2-diol, propane-1,3-diol, butane-1,3-diol, butene-1,4-diol, butyne-1,4-diol, pentane-1,5- diol, neopentyl glycol, bis (hydroxymethyl) cyclohexanes such as 1,4-bis (hydroxymethyl) cyclohexane, 2-methylpropane-1,3-diol, methylpentanediols, furthermore diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, dipropylene glycol, polypropylene glycol, Dibutylene glycol and polybutylene glycols into consideration. Alcohols of the general formula HO- (CH ₂ ) _x -OH, where x is a number from 1 to 20, preferably an even number from 2 to 20, are preferred. Examples of these are ethylene glycol, butane-1,4-diol, hexane-1,6-diol, octane-1,8-diol and dodecane-1,12-diol. Further preferred is neopentyl glycol.

The proportion of the diols (b ₁ ), based on the total amount of the diols (b), is preferably 10 to 100 mol% and the proportion of the monomers (b ₂ ), based on the total amount of the diols (b), is 0 to 90 mol%. %. The ratio of the diols (b ₁ ) to the monomers (b ₂ ) is particularly preferably 0.1: 1 to 5: 1, particularly preferably 0.2: 1 to 2: 1.

In order to achieve the water-dispersibility of the polyurethanes, the polyurethanes of components (a), (b) and (d) contain various monomers (c) containing at least one isocyanate group or at least one isocyanate-reactive group and moreover at least one hydrophilic group or groups carry a group that can be converted into a hydrophilic group, as a structural component. In the following text, the term "hydrophilic groups or potentially hydrophilic groups" is abbreviated to "(potentially) hydrophilic groups". The (potentially) hydrophilic groups react much more slowly with isocyanates than the functional groups of the monomers which serve to build up the polymer main chain.

The proportion of components having (potentially) hydrophilic groups in the total amount of components (a), (b), (c), (d) and (e) is generally such that the molar amount of (potentially) hydrophilic groups, based on the amount by weight of all monomers (a) to (e), 30 to 1000, preferably 50 to 500 and particularly preferably 80 to 300 mmol / kg. The (potentially) hydrophilic groups may be nonionic or, preferably, (potentially) ionic hydrophilic groups. Suitable nonionic hydrophilic groups are, in particular, polyethylene glycol ethers of preferably from 5 to 100, preferably from 10 to 80, ethylene oxide repeat units. The content of polyethylene oxide units is generally 0 to 10, preferably 0 to 6 wt .-%, based on the amount by weight of all monomers (a) to (e).

Preferred monomers having nonionic hydrophilic groups are polyethylene oxide diols containing at least 20% by weight of ethylene oxide, polyethylene oxide monools and the reaction products of a polyethylene glycol and a diisocyanate which carry a terminally etherified polyethylene glycol radical. Such diisocyanates and processes for their preparation are in the patents US Pat. No. 3,905,929 and US-A 3,920,598 specified.

Ionic hydrophilic groups are especially anionic groups such as the sulfonate, the carboxylate and the phosphate group in the form of their alkali metal or ammonium salts and cationic groups such as ammonium groups, in particular protonated tertiary amino groups or quaternary ammonium groups. Potentially ionic hydrophilic groups are especially those which can be converted by simple neutralization, hydrolysis or quaternization into the above-mentioned ionic hydrophilic groups, ie, for. As carboxylic acid groups or tertiary amino groups. (Potentially) ionic monomers (c) are e.g. In Ullmanns Enzyklopadie der technischen Chemie, 4th Edition, Volume 19, pp. 311-313 and for example in the DE-A 1 495 745 described in detail.

As (potentially) cationic monomers (c), especially monomers having tertiary amino groups are of particular practical importance, for example: tris- (hydroxyalkyl) -amines, N, N'-bis (hydroxyalkyl) -alkylamines, N-hydroxyalkyl-dialkylamines, tris - (aminoalkyl) -amines, N, N'-bis (aminoalkyl) -alkylamines, N-aminoalkyl-dialkylamines, wherein the alkyl radicals and alkanediyl moieties of these tertiary amines independently of one another consist of 1 to 6 carbon atoms. Furthermore, tertiary nitrogen atoms having polyethers having preferably two terminal hydroxyl groups, as z. Example, by alkoxylation of two bound to amine nitrogen hydrogen atoms containing amines, eg. As methylamine, aniline or N, N'-dimethylhydrazine, are accessible in a conventional manner, into consideration. Such polyethers generally have a molecular weight between 500 and 6000 g / mol. These tertiary amines are either with acids, preferably strong mineral acids such as phosphoric acid, sulfuric acid, hydrohalic acids or strong organic acids or by reaction with suitable quaternizing agents such as C ₁ - to C ₆ -alkyl halides or benzyl halides, eg. As bromides or chlorides, transferred to the ammonium salts.

in welcher R¹ und R² für eine C₁- bis C₄-Alkandiyl-(Einheit) und R³ für eine C₁- bis C₄-Alkyl-(Einheit) steht und vor allem Dimethylolpropionsäure (DMPA) bevorzugt. Weiterhin eignen sich entsprechende Dihydroxysulfonsäuren und Dihydroxyphosphonsäuren wie 2,3-Dihydroxypropanphosphonsäure. Ansonsten geeignet sind Dihydroxylverbindungen mit einem Molekulargewicht über 500 bis 10000 g/mol mit mindestens 2 Carboxylatgruppen, die aus der DE-A 3 911 827 bekannt sind. Sie sind durch Umsetzung von Dihydroxylverbindungen mit Tetracarbonsäuredianhydriden wie Pyromellitsäuredianhydrid oder Cyclopentantetracarbonsäuredianhydrid im Molverhältnis 2:1 bis 1,05:1 in einer Polyadditionsreaktion erhältlich. Als Dihydroxylverbindungen sind insbesondere die als Kettenverlängerer aufgeführten Monomere (b2) sowie die Diole (b1) geeignet. Suitable monomers with (potentially) anionic groups are usually aliphatic, cycloaliphatic, araliphatic or aromatic carboxylic acids and sulfonic acids which carry at least one alcoholic hydroxyl group or at least one primary or secondary amino group. Preference is given to dihydroxyalkylcarboxylic acids, especially having 3 to 10 carbon atoms, as they are also in the US-A 3 412 054 are described. In particular, compounds of the general formula (c ₁ )

in which R ¹ and R ^{2 is} a C ₁ - to C ₄ -alkanediyl (unit) and R ^{3 is} a C ₁ - to C ₄ -alkyl- (unit) and, in particular, dimethylolpropionic acid (DMPA) is preferred. Also suitable are corresponding dihydroxysulfonic acids and dihydroxyphosphonic acids, such as 2,3-dihydroxypropanephosphonic acid. Otherwise suitable are dihydroxyl compounds having a molecular weight above 500 to 10,000 g / mol with at least 2 carboxylate groups, which from the DE-A 3 911 827 are known. They are obtainable by reacting dihydroxyl compounds with tetracarboxylic dianhydrides such as pyromellitic dianhydride or cyclopentanetetracarboxylic dianhydride in a molar ratio of 2: 1 to 1.05: 1 in a polyaddition reaction. Particularly suitable dihydroxyl compounds are the monomers (b2) listed as chain extenders and also the diols (b1).

As monomers (c) with isocyanate-reactive amino groups are aminocarboxylic acids such as lysine, β-alanine or in the DE-A 2034479 mentioned adducts of aliphatic diprimary diamines to alpha, beta-unsaturated carboxylic or sulfonic acids into consideration. Such compounds obey, for example, the formula (c ₂ ) H ₂ NR ⁴ -NH-R ⁵ -X (c ₂ ) in which R ⁴ and R ⁵ independently of one another are a C ₁ - to C ₆ -alkanediyl unit, preferably ethylene and X is COOH or SO ₃ H.

Particularly preferred compounds of the formula (c ₂ ) are N- (2-aminoethyl) -2-aminoethanecarboxylic acid and also N- (2-aminoethyl) -2-aminoethanesulfonic acid or the corresponding alkali metal salts, Na being particularly preferred as the counterion. Also particularly preferred are the adducts of the abovementioned aliphatic diprimary diamines with 2-acrylamido-2-methylpropanesulfonic acid, as described, for example, in US Pat. B. in the DE-B 1 954 090 are described.

If monomers having potentially ionic groups are used, their conversion into the ionic form may take place before, during, but preferably after the isocyanate polyaddition, since the ionic monomers are often difficult to dissolve in the reaction mixture. The sulfonate or carboxylate groups are particularly preferably in the form of their salts with an alkali ion or an ammonium ion as the counterion.

The monomers (d), which are different from the monomers (a) to (c) and which are optionally also constituents of the polyurethane, generally serve for crosslinking or chain extension. They are generally more than divalent non-phenolic alcohols, amines having 2 or more primary and / or secondary amino groups, and compounds which carry one or more primary and / or secondary amino groups in addition to one or more alcoholic hydroxyl groups. Alcohols with a value higher than 2, which can serve to set a certain degree of branching or crosslinking, z. B. trimethylolpropane, glycerol or sugar. Also suitable are monoalcohols which, in addition to the hydroxyl group, carry a further isocyanate-reactive group, such as monoalcohols having one or more primary and / or secondary amino groups, eg. B. monoethanolamine.

Polyamines having 2 or more primary and / or secondary amino groups are used especially when the chain extension or crosslinking is to take place in the presence of water, since amines usually react faster than alcohols or water with isocyanates. This is often required when aqueous dispersions of high molecular weight crosslinked polyurethanes or polyurethanes are desired. In such cases, the procedure is to prepare prepolymers with isocyanate groups, to rapidly disperse them in water and then to chain extend or crosslink them by adding compounds containing several isocyanate-reactive amino groups. Suitable amines for this purpose are generally polyfunctional amines of the molecular weight range from 32 to 500 g / mol, preferably from 60 to 300 g / mol, which contain at least two amino groups selected from the group of primary and secondary Amino groups, contained. Examples of these are diamines such as diaminoethane, diaminopropanes, diaminobutanes, diaminohexanes, piperazine, 2,5-dimethylpiperazine, amino-3-aminomethyl-3,5,5-trimethyl-cyclohexane (isophoronediamine, IPDA), 4,4'-diaminodicyclohexylmethane, 1 , 4-diaminocyclohexane, aminoethylethanolamine, hydrazine, hydrazine hydrate or triamines such as diethylenetriamine or 1,8-diamino-4-aminomethyloctane.

The amines may also be in blocked form, for. In the form of the corresponding ketimines (see eg. CA-A 1 129 128 ), Ketazines (cf., for example, the US Pat. No. 4,269,748 ) or amine salts (s. US-A 4,292,226 ) are used. Oxazolidines, as used for example in the US-A 4,192,937 are used represent blocked polyamines, which can be used for the preparation of polyurethanes according to the invention for chain extension of prepolymers. In the use of such capped polyamines they are generally mixed with the prepolymers in the absence of water and this mixture is then mixed with the dispersion water or a portion of the dispersion water, so that the corresponding polyamines are hydrolytically released.

Preference is given to using mixtures of di- and triamines, particularly preferably mixtures of isophoronediamine (IPDA) and diethylenetriamine (DETA).

The polyurethanes preferably contain from 1 to 30, particularly preferably from 4 to 25, mol%, based on the total amount of components (b) and (d), of a polyamine having at least 2 isocyanate-reactive amino groups as monomers (d). For the same purpose higher than divalent isocyanates can also be used as monomers (d). Commercially available compounds are, for example, the isocyanurate or the biuret of hexamethylene diisocyanate.

Monomers (e), which are optionally used, are monoisocyanates, monoalcohols and monoprimers and -secondary amines. In general, their proportion is at most 10 mol%, based on the total molar amount of the monomers. These monofunctional compounds usually carry further functional groups such as olefinic groups or carbonyl groups and serve to introduce functional groups into the polyurethane, which enable the dispersion or the crosslinking or further polymer-analogous reaction of the polyurethane. suitable for this purpose are monomers such as isopropenyl-α, α-dimethylbenzyl isocyanate (TMI) and esters of acrylic or methacrylic acid such as hydroxyethyl acrylate or hydroxyethyl methacrylate.

Adhesives having a particularly good property profile are obtained especially when, as monomers (a), essentially only aliphatic diisocyanates, cycloaliphatic diisocyanates or araliphatic diisocyanates are used. This monomer combination is excellently supplemented as component (c) by diaminosulfonic acid-alkali salts; in particular by the N- (2-aminoethyl) -2-aminoethanesulfonic acid or its corresponding alkali metal salts, the Na salt being most suitable, and a mixture of DETA / IPDA as component (d).

In the field of polyurethane chemistry, it is well known how the molecular weight of the polyurethanes can be adjusted by selecting the proportions of the monomers reactive with each other and the arithmetic mean of the number of reactive functional groups per molecule.

• A der Molmenge an Isocyanatgruppen und
• B der Summe aus der Molmenge der Hydroxylgruppen und der Molmenge der funktionellen Gruppen, die mit Isocyanaten in einer Additionsreaktion reagieren können,

0,5:1 bis 2:1, bevorzugt 0,8:1 bis 1,5, besonders bevorzugt 0,9:1 bis 1,2:1 beträgt. Ganz besonders bevorzugt liegt das Verhältnis A:B möglichst nahe an 1:1.Normally, the components (a) to (e) and their respective molar amounts are chosen so that the ratio A: B with

• A is the molar amount of isocyanate groups and
• B is the sum of the molar amount of the hydroxyl groups and the molar amount of the functional groups which can react with isocyanates in an addition reaction,

0.5: 1 to 2: 1, preferably 0.8: 1 to 1.5, more preferably 0.9: 1 to 1.2: 1. Most preferably, the ratio A: B is as close as possible to 1: 1.

The monomers used (a) to (e) carry on average usually 1.5 to 2.5, preferably 1.9 to 2.1, particularly preferably 2.0 isocyanate groups or functional groups which can react with isocyanates in an addition reaction ,

The polyaddition of components (a) to (e) for the preparation of the polyurethane is preferably carried out at reaction temperatures of up to 180 ° C, preferably up to 150 ° C under atmospheric pressure or under autogenous pressure. The preparation of polyurethanes or of aqueous polyurethane dispersions is known to the person skilled in the art.

If carbodiimides are to be bound to the polyurethane, it is possible in the preparation of the polyurethanes to use carbodiimides having terminal isocyanate groups (see above) as diisocyanates a) in the desired amount.

The polymeric binder may also be a free-radically polymerized polymer, ie the polymer is obtainable by free-radical polymerization of ethylenically unsaturated compounds (monomers). The polymer is preferably at least 40 wt .-%, preferably at least 60 wt .-%, more preferably at least 80 wt .-% of so-called main monomers. The main monomers are selected from C ₁ -C ₂₀ -alkyl (meth) acrylates, vinyl esters of carboxylic acids containing up to 20 carbon atoms, vinylaromatics having up to 20 carbon atoms, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of from 1 to 10 carbon atoms. Atoms containing alcohols, aliphatic hydrocarbons having 2 to 8 carbon atoms and one or two double bonds or mixtures of these monomers. To name a few are z. B. (meth) acrylic acid alkyl ester having a C ₁ -C ₁₀ alkyl radical, such as methyl methacrylate, methyl acrylate, n-butyl acrylate, ethyl acrylate and 2-ethylhexyl acrylate. In particular, mixtures of (meth) acrylic acid alkyl esters are also suitable.

Vinyl esters of carboxylic acids having 1 to 20 carbon atoms are, for. As vinyl laurate, stearate, vinyl propionate, vinyl versatate and vinyl acetate. Suitable vinylaromatic compounds are vinyltoluene, α- and p-methylstyrene, α-butyl-styrene, 4-n-butylstyrene, 4-n-decylstyrene and preferably styrene. Examples of nitriles are acrylonitrile and methacrylonitrile. The vinyl halides are chloro, fluoro or bromo substituted ethylenically unsaturated compounds, preferably vinyl chloride and vinylidene chloride. To name as vinyl ethers are, for. As vinyl methyl ether or vinyl isobutyl ether. Vinyl ether is preferably from 1 to 4 C-containing alcohols. As hydrocarbons having 2 to 8 carbon atoms and one or two olefinic double bonds may be mentioned ethylene, propylene, butadiene, isoprene and chloroprene.

Preferred main monomers are the C ₁ - to C ₁₀ -alkyl acrylates and -methacrylates, in particular C ₁ - to C ₈ -alkyl acrylates and -methacrylates and vinylaromatics, in particular styrene and mixtures thereof. Very particular preference is given to methyl acrylate, methyl methacrylate, ethyl acrylate, n-butyl acrylate, n-hexyl acrylate, octyl acrylate and 2-ethylhexyl acrylate, styrene and mixtures of these monomers.

In addition to the main monomers, the polymer may contain other monomers, for. As monomers with carboxylic acid, sulfonic acid or phosphonic acid groups. Preferred are carboxylic acid groups. Called z. For example, acrylic acid, methacrylic acid, itaconic acid, maleic acid or fumaric acid. Other monomers are z. As well as hydroxyl-containing monomers, in particular C ₁ -C ₁₀ hydroxyalkyl (meth) acrylates, (meth) acrylamide. Phenyloxyethylglycol mono (meth) acrylate, glycidyl acrylate, glycidyl methacrylate, amino (meth) acrylates such as 2-aminoethyl (meth) acrylate may also be mentioned as further monomers. Other monomers which may also be mentioned are crosslinking monomers.

More preferably, the polymer is at least 40 wt .-%, in particular at least 60 wt .-% and most preferably at least 80 wt .-% of C ₁ -C ₂₀ -, in particular C ₁ -C ₁₀ alkyl (meth) acrylates ,

The polymers are prepared in a preferred embodiment by emulsion polymerization, it is therefore an emulsion polymer. However, the production can z. B. also be carried out by solution polymerization and subsequent dispersion in water. In summary, the adhesive is preferably an aqueous adhesive. The polymeric binder is preferably in the form of an aqueous dispersion. Other additives can be added in a simple manner to the aqueous dispersion of the polymeric binder.

An essential feature of the method according to the invention is that the adhesive is applied to the flexible substrate. In this case, a flexible substrate is understood to be a planar substrate which, with a substrate area of 50 × 50 cm, held parallel to the earth's surface on one side, bends through its own weight. Preferably, it is a substrate which on drums having an outer diameter of z. B. 80 cm can be wound up. Preferably, the flexible substrate is flat substrates with a thickness of less than 10 mm, in particular less than 5 mm, more preferably less than 0.5 mm, very particularly preferably less than 0.3 mm. In particular, it may be polymeric films, metal foils, nonwovens made of synthetic or natural fibers, coated or uncoated paper or even veneers made of wood or imitation wood. Particularly preferred are polymer films, for. As films of polyester, such as polyethylene terephthalate, polyolefins, such as polyethylene, polypropylene or polyvinyl chloride.

The flexible substrate may be pretreated, e.g. B. it may be coated with adhesion promoters. The flexible substrate may also be constructed of several layers; comes into consideration for. B. a carrier layer of the above polymers and on this carrier layer one or both sides applied protective coatings or decorative coatings.

The non-flexible substrate may be a shaped article whose outer shape remains the same, even if this shaped article is loaded with its own weight, e.g. B. by the molding is held free-hanging only at a single arbitrary point. The above information refers to normal conditions (21 ° C, 1 bar). The non-flexible substrate may be made of wood or plastic, e.g. For example, be ABS (acrylonitrile-butadiene-styrene). It can be z. B. act solid wood or plywood. In particular, it may be molded parts, which are composed of synthetic or natural fibers or chips. The moldings can have any shape.

In the method according to the invention, the flexible substrate is coated with adhesive. The coating can be carried out by customary application methods. After coating, drying takes place, preferably at room temperature or temperatures up to 80 ° C., in order to remove water or other solvents. The amount of adhesive applied is preferably 0.5 to 100 g / m ² , more preferably 2 to 80 g / m ² , most preferably 10 to 70 g / m ² . Thereafter, the adhesive-coated substrate can be stored; For this purpose, it may, for. B. are wound on rollers. Preferably, the coated substrate is wound up after drying if necessary. Prior to further processing, storage or else transport generally takes place, so that a time of more than one week, or more than 3 weeks, in particular also more than 6 weeks, or more than 10 weeks, passes until further processing. The coated substrate is stable on storage, ie even after several weeks of storage time, the coated substrate can be processed with good results.

For bonding to the non-flexible substrate, the parts to be bonded are joined together. The temperature in the adhesive layer is preferably 20 to 200 ° C or 30 to 200 ° C or 30 to 180 ° C. Conveniently, the coated flexible substrate may be heated to appropriate temperatures. The bonding is preferably carried out under pressure, this can, for. B. the parts to be bonded are pressed together with a pressure of 0.05 to 5 N / mm ² .

The composites obtained are characterized by high mechanical strength even at elevated temperatures (heat resistance) or under strongly changing climatic conditions (climatic resistance). These good results are also achieved when the coated flexible substrate is adhered for a long time, e.g. B. was stored for more than 3 months. Compared to the hitherto conventional methods (coating of the non-flexible substrate), the strengths are even higher. Of particular importance has the inventive method in the automotive or furniture industry, z. As in the bonding of flexible substrates on car interior parts, such as dashboards, door trim and hat racks.

The invention also relates to flat, flexible substrates bonded non-flexible substrates, obtainable by the inventive method. The invention also provides flexible substrates of at least one flexible carrier and an adhesive coating, the adhesive coating containing 0.0001 to 0.1 mol of carbodiimide groups per 100 g of adhesive, calculated on solvent-free adhesive, wherein the carbodiimide-containing compounds of the adhesive have urea groups and these urea groups can be prepared by hydrolysis of carbodiimide compounds containing isocyanate groups or by reacting isodiisocyanate-containing carbodiimide compounds with non-polymeric, acid-group-free amine compounds. The carbodiimide compounds containing urea groups are particularly preferably preparable by hydrolysis of carbodiimide compounds containing isocyanate groups, the carbodiimide compounds containing isocyanate groups being emulsified in water and stirred until no more isocyanate groups are detectable.

Examples

CDI

Carbodiimid

DETA

Diethylentriamin

DMPA

Dimethylolpropionsäure

EDA

Ethylendiamin-1,2

EH

2-Ethylhexanol

HDA

Hexamethylendiamin-1,6

HDI

Hexamethylendiisocyanat-1,6

IPDA

Isophorondiamin

IPDI

Isophorondiisocyanat

MPG

Methylpolyglykol des zahlenmittleren Molgewichts 500 g/mol

MPO

Gemisch aus 1-Methyl-2-phospholenoxid und 1-Methyl-3-phospholenoxid (1/1)

PUD

Polyurethandispersion

TBOT

Tetrabutylorthotitanat

TMXDI

m-Tetramethylxylylendiisocyanat

TMXDI-CDI

Carbodiimid-Diisocyanat, das nach der Lehre der DE 4318979 aus TMXDI hergestellt ist.

The following abbreviations are used:

CDI

carbodiimide

DETA

diethylenetriamine

DMPA

dimethylolpropionic

EDA

Ethylenediamine-1,2

EH

2-ethylhexanol

HDA

1,6-hexamethylenediamine

HDI

Hexamethylene 1,6-diisocyanate

IPDA

isophoronediamine

IPDI

isophorone

MPG

Methyl polyglycol of number average molecular weight 500 g / mol

MPO

Mixture of 1-methyl-2-phospholene oxide and 1-methyl-3-phospholene oxide (1/1)

PUD

polyurethane dispersion

TBOT

tetrabutyl

TMXDI

m-tetramethylxylylene

TMXDI-CDI

Carbodiimide diisocyanate, which according to the teaching of DE 4318979 made of TMXDI.

Percentages are by weight unless otherwise stated.

To determine the glass transition temperature, samples obtained by drying at room temperature were measured in a device DSC822 (TA8000 series) from Mettler-Toledo.

Polyurethane dispersion PUD

In a stirred flask with reflux condenser and thermometer were 751 g (0.30 mol) of a polyester of OH number 44.8 of adipic acid and 1,4-butanediol, 4.83 g (0.036 mol) of DMPA, 0.13 g TBOT and 50 g of acetone at 60 ° C presented. To this was added 50.46 g (0.227 mol) of IPDI and 44.9 g (0.267 mol) of HDI and stirred at 88 ° C for 270 min. It was then diluted with 800 g of acetone and cooled to 50 ° C. The NCO content of the solution was determined to be 0.78%. To this was added 40.63 g of a 50% aqueous solution of the sodium salt of 2'-aminoethane-2-ethanesulfonic acid. After 5 minutes, 0.50 g of a 25% aqueous solution of KOH was added. Then it was dispersed with 1000 g of water. After distillation of the acetone, an aqueous polyurethane dispersion having a solids content of 44% was obtained.

1. urea groups by saponification of isocyanate carbodiimides

1.1 Comparative Example, carbodiimide without urea groups

85 g of TMXDI-CDI having an NCO content of 7.6% by weight were stirred in a stirred flask with 76.9 g of MPG at 95 ° C. for 600 minutes until an NCO content of <0.1% had been reached , 40 g of the reaction product were placed in a beaker, poured with 360 g of water and stirred with a dispersing disc of 5 cm diameter at 800 rev / min at 25 ° C for 20 minutes.

1.2

70 g of TMXDI-CDI having an NCO content of 7.6% were stirred in a stirred flask with 31.5 g of MPG at 95 ° C. for 120 minutes until an NCO content of 2.50% was reached. 40 g of the reaction product were placed in a beaker, poured with 360 g of water and stirred with a dispersing disc of 5 cm diameter at 800 rev / min at 25 ° C for 20 minutes. After 24 hours, the NCO content of the dispersion had fallen to <0.1%.

1.3

80 g of TMXDI-CDI having an NCO content of 7.6% were stirred in a stirred flask with 24.5 g of MPG at 95 ° C. for 120 minutes until an NCO content of 3.89% had been reached. 40 g of the reaction product were placed in a beaker, poured with 360 g of water and stirred with a dispersing disc of 5 cm diameter at 800 rev / min at 25 ° C for 20 minutes. After 24 hours, the NCO content of the dispersion had fallen to <0.1%.

1.4

85 g of TMXDI-CDI having an NCO content of 7.6% were stirred in a stirred flask with 14.0 g of MPG at 95 ° C. for 120 minutes until an NCO content of 5.20% had been reached. 40 g of the reaction product were placed in a beaker, poured with 360 g of water and stirred with a dispersing disc of 5 cm diameter at 800 rev / min at 25 ° C for 20 minutes. After 24 hours, the NCO content of the dispersion had fallen to <0.1%. Table 1: Urea by saponification of TMXDI example NCO content before dispersion (%) NCN content (%) Tg (° C) 1.1 (comparison) <0.1 8.2 -41 1.2 2.50 10.8 -32 1.3 3.89 11.9 -20 1.4 5.20 13.4 -7

Urethane from IPDI and MPG

600 g (2.7 mol) of IPDI were stirred with 378 g (0.76 mol) MPG in a stirred flask at 95 ° C for 120 minutes until an NCO content of 22.6% was reached.

1.5.

100 g of the urethane were heated to 180 ° C and added 0.20 g of MPO. After 150 minutes, the NCO content had fallen to 5.1%. 40 g of the reaction product were placed in a beaker, poured with 360 g of water and stirred with a dispersing disc of 5 cm diameter at 800 rev / min at 25 ° C for 20 minutes. After 24 hours, the NCO content of the dispersion had fallen to <0.1%.

1.6.

100 g of the urethane were heated to 180 ° C and added 0.20 g of MPO. After 190 minutes, the NCO content had fallen to 4.1%. 40 g of the reaction product were placed in a beaker, poured with 360 g of water and stirred with a dispersing disc of 5 cm diameter at 800 rev / min at 25 ° C for 20 minutes. After 24 hours, the NCO content of the dispersion had fallen to <0.1%.

1.7.

100 g of the urethane were heated to 180 ° C and added 0.20 g of MPO. After 250 minutes, the NCO content had fallen to 3.1%. 40 g of the reaction product were placed in a beaker, poured with 360 g of water and stirred with a dispersing disc of 5 cm diameter at 800 rev / min at 25 ° C for 20 minutes. After 24 hours, the NCO content of the dispersion had fallen to <0.1%.

1.8.

100 g of the urethane were heated to 180 ° C and added 0.20 g of MPO. After 360 minutes, the NCO content had dropped to 1.9%. 40 g of the reaction product were placed in a beaker, poured with 360 g of water and stirred with a dispersing disc of 5 cm diameter at 800 rev / min at 25 ° C for 20 minutes. After 24 hours, the NCO content of the dispersion had fallen to <0.1%.

In all cases of Examples 1.5 to 1.8, finely divided, stable dispersions of a urea group-containing IPDI carbodiimide were obtained.

1.9.

600 g (2.7 mol) of IPDI were stirred with 320 g (0.66 mol) of MPG and 13 g (0.10 mol) of EH in a stirred flask at 95 ° C for 120 minutes until an NCO content of 22.2 % was reached. 100 g of the urethane were on Heated to 180 ° C and 0.20 g of MPO was added. After 200 minutes, the NCO content had dropped to 4.1%. 40 g of the reaction product were placed in a beaker, poured with 360 g of water and stirred with a dispersing disc of 5 cm diameter at 800 rev / min at 25 ° C for 20 minutes. After 24 hours, the NCO content of the dispersion had fallen to <0.1%.

1.10.

600 g (2.7 mol) of IPDI were stirred with 280 g (0.56 mol) of MPG and 26 g (0.20 mol) of EH in a stirred flask at 95 ° C for 120 minutes until an NCO content of 22.5 % was reached. 100 g of the urethane were heated to 180 ° C and added 0.20 g of MPO. After 200 minutes, the NCO content had fallen to 4.2%. 40 g of the reaction product were placed in a beaker, poured with 360 g of water and stirred with a dispersing disc of 5 cm diameter at 800 rev / min at 25 ° C for 20 minutes. After 24 hours, the NCO content of the dispersion had fallen to <0.1%.

11.1.

600 g (2.7 mol) of IPDI were stirred with 230 g (0.46 mol) of MPG and 39 g (0.30 mol) of EH in a stirred flask at 95 ° C for 120 minutes until an NCO content of 22.0 % was reached. 100 g of the urethane were heated to 180 ° C and added 0.20 g of MPO. After 200 minutes, the NCO content had fallen to 4.3%. 40 g of the reaction product were placed in a beaker, poured with 360 g of water and stirred with a dispersing disc of 5 cm diameter at 800 rev / min at 25 ° C for 20 minutes. After 24 hours, the NCO content of the dispersion had fallen to <0.1%.

1.12.

600 g (2.7 mol) of IPDI were stirred with 180 g (0.36 mol) of MPG and 52 g (0.40 mol) of EH in a stirred flask at 95 ° C for 120 minutes until an NCO content of 22.4 % was reached. 100 g of the urethane were heated to 180 ° C and added 0.20 g of MPO. After 200 minutes, the NCO content had dropped to 4.1%. 40 g of the reaction product were placed in a beaker, poured with 360 g of water and stirred with a dispersing disc of 5 cm diameter at 800 rev / min at 25 ° C for 20 minutes. After 24 hours, the NCO content of the dispersion had fallen to <0.1%.

In all cases of Examples 1.9 to 1.12, finely divided, stable dispersions of a urea group-containing IPDI carbodiimide were obtained.

2. Urea groups by addition of amine to TMXDI carbodiimide

There were 340 parts of a polycarbodiimide having an NCO content of 7.5 wt .-%, which according to the teaching of DE 4318979 was reacted in a stirred flask with 60 g MPG at 100 ° C until an NCO content of 4.90% was reached. Each 60 g of the reaction product was then dispersed in 240 g of water and stirred at 25 ° C for 5 minutes. After this time, the amines indicated in Table 2 were added with stirring. Table 2: Urea by addition of amine example Amin Mass (g) Tg (° C) 2.2 HDA 4.10 -10.9 2.3 IPDA 5.00 -8.2 2.4 DETA 3.60 -5.6 2.5 HDA 2.05 -9.5 2.6 EDA 1.03 -6.3 2.7 IPDA 2.92 -7.6 2.8 DETA 1.18 -6.6

3. Urea groups by addition of amine to IPDI carbodiimide

3.1

160 g of IPDI were heated to 90 ° C and added 32.45 g of MPG. After 150 minutes at 90 ° C, the NCO content had fallen to 29.5 wt .-%. Now it was heated to 145 ° C and added 0.32 g of MPO. After 13 hours, the NCO content had fallen to 3.9%. Now 21.0 g of 2-ethylhexylamine were added and stirred for a further 16 hours at 145 ° C until an NCO content of 0.17% was reached. 2.0 g of 2-ethylhexylamine were added and the mixture was stirred at 145 ° C. for a further six hours. Afterwards the NCO content was <0.1%. The glass transition temperature was determined to be 21.0 ° C.

3.2

160 g of IPDI were heated to 90 ° C and added 32.45 g of MPG. After 150 minutes at 90 ° C, the NCO content had fallen to 29.9 wt .-%. Now it was heated to 145 ° C and added 0.32 g of MPO. After 14 hours, the NCO content had fallen to 4.2%. Now 10.0 g of 1-propylamine were added and stirred at 145 ° C for 24 hours until an NCO content <0.1% was reached. The glass transition temperature was determined to be 26.0 ° C.

3.3

160 g of IPDI were heated to 90 ° C and added 32.45 g of MPG. After 150 minutes, the mixture was heated to 145 ° C. and 0.32 g of MPO were added. After 13 hours, the NCO content had fallen to 4.4%. Now 13.0 g of 1-butylamine were added and stirred at 145 ° C for 24 hours until an NCO content <0.1% was reached. The glass transition temperature was determined to be 27.0 ° C.

3.4

160 g of IPDI were heated to 90 ° C and added 19.95 g of 1-octylamine. After 150 minutes, the mixture was heated to 145 ° C. and 0.32 g of MPO were added. After 21 hours, the NCO content had dropped to 5.5%. Now 132.5 g MPG were added and stirred for 17 hours at 145 ° C until an NCO content <0.1% was reached. The glass transition temperature was determined to be -48.9 ° C.

Testing for effectiveness as a crosslinker

13.2 g of the CDI dispersions according to Examples 1.2 to 1.4 were mixed to 100 g of the PUD. The resulting dispersions or dried films prepared therefrom were stored for different times at different temperatures (RT: room temperature, 25 ° C.). Subsequently, the K value was determined. The K value is a measure of the molecular weight of a polymer. An increase in the K value indicates an increase in molecular weight and is an indication of a crosslinking reaction. The lower the increase in the K value, the more stable the composition is. example Storage as storage conditions K value PUD without CDI dispersion RT, 14 d 58.4 1.2 dispersion RT, 14 d 76.2 1.3 dispersion RT, 14 d 73.2 1.4 dispersion RT, 14 d 68.9 PUD without CDI Movie RT, 5 d 59.9 1.2 Movie RT, 5 d 64.4 1.3 Movie RT, 5 d 63.1 1.4 Movie RT, 5 d 61.2 PUD without CDI Movie 40 ° C, 5 d 59.9 1.2 Movie 40 ° C, 5 d 66.3 1.3 Movie 40 ° C, 5 d 64.4 1.4 Movie 40 ° C, 5 d 62.0 PUD without CDI Movie 100 ° C, 3 h 61.3 1.2 Movie 100 ° C, 3 h 83.2 1.3 Movie 100 ° C, 3 h 84.5 1.4 Movie 100 ° C, 3 h 78.6

The examples show that the reactivity of the PUD / CDI dispersions can be selectively adjusted by varying the urea content. By increasing the urea content, the storage stability can be significantly improved.

QUOTES INCLUDE IN THE DESCRIPTION

This list of the documents listed by the applicant has been generated automatically and is included solely for the better information of the reader. The list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions.

Cited patent literature

• DE 10330748 A1 [0003]
• EP 0622378A [0029]
• US 3905929 A [0035]
• US Pat. No. 3,920,598 A [0035]
• DE 1495745A [0036]
• US 3412054 A [0038]
• DE 3911827 A [0038]
• DE 2034479 A [0039]
• DE 1954090 B [0040]
• CA 1129128A [0044]
• US 4269748A [0044]
• US Pat. No. 4,292,226 A [0044]
• US 4192937 A [0044]
• DE 4318979 [0067, 0086]

Cited non-patent literature

• Ullmanns Enzyklopadie der technischen Chemie, 4th Edition, Volume 19, pp. 62 to 65 [0023]
• Ullmanns Enzyklopadie der technischen Chemie, 4th Edition, Volume 19, pp. 311-313 [0036]

Claims (17)

A method of bonding sheet-like flexible substrates to non-flexible substrates, wherein an adhesive is applied to the flexible substrate and the adhesive-coated flexible substrate is adhered to the non-flexible substrate, wherein the adhesive used for the bonding is 0.0001 to 0.1 mol of carbodiimide groups per 100 g of adhesive, calculated on solvent-free adhesive, and wherein the carbodiimide-containing compounds of the adhesive have urea groups and these urea groups can be prepared by hydrolysis of isocyanate-containing carbodiimide compounds or by reacting isocyanate-containing carbodiimide compounds with non-polymeric, acid group-free amine compounds. A method according to claim 1, characterized in that the amount of urea groups is greater than 0.01 mol per 100 g of carbodiimide-containing compounds. A method according to claim 2, characterized in that the amount of urea groups 0.01 to 1 mol per 100 g of carbodiimide-containing compounds. Process according to one of the preceding claims, characterized in that the carbodiimide compounds containing urea groups can be prepared by hydrolysis of carbodiimide compounds containing isocyanate groups, the carbodiimide compounds containing isocyanate groups being emulsified in water and stirred until no more isocyanate groups are detectable. Method according to one of the preceding claims, characterized in that the adhesive consists of at least 60 wt .-% of a polyurethane, a free-radically polymerized polymer or mixtures thereof. A method according to the preceding claim, characterized in that the polyurethane is at least 60 wt .-% of diisocyanates, polyether diols and / or polyester diols and has a melting point in the range of -50 to 150 ° C, preferably from 0 to 100 ° C. and the free-radically polymerized polymer is composed of at least 60% by weight of so-called main monomers selected from C1 to C20 alkyl (meth) acrylates, vinyl esters of carboxylic acids containing up to 20 carbon atoms, vinyl aromatics having up to 20 carbon atoms, ethylenically unsaturated nitriles, vinyl halides, vinyl ethers of alcohols containing 1 to 10 C atoms, aliphatic hydrocarbons having 2 to 8 C atoms and one or two double bonds or mixtures of these monomers. Method according to one of the preceding claims, characterized in that the adhesive coating contains compounds having on average 2 to 10 carbodiimide groups per molecule. Process according to any one of the preceding claims, characterized in that the compounds containing carbodiimide groups are attached to a polymer, e.g. As a polyurethane or free-radically polymerized polymer are bound. A process according to any one of the preceding claims, characterized in that the compound containing carbodiimide groups is a carbodiimide based on tetramethylxylylene diisocyanate (TMXDI) or based on 1-isocyanato-3,5,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI) , Method according to one of the preceding claims, characterized in that for the coating of the flexible substrate, an aqueous adhesive is used and the polyurethane or the radically polymerized polymer in the form of aqueous dispersions. Method according to one of the preceding claims, characterized in that it is the flexible substrate is a polymer film or a wood veneer and the non-flexible substrate is molded parts made of wood or plastic. Method according to one of the preceding claims, characterized in that the non-flexible substrate is molded parts made of natural or synthetic fibers or chips. Method according to one of the preceding claims, characterized in that the adhesive is applied to the flexible substrate, optionally drying to remove water or organic solvents takes place and the adhesive layer is heated to temperatures of 30 to 200 ° C in the subsequent bonding with the non-flexible substrate. Method according to one of the preceding claims, characterized in that the flexible substrate is wound up after coating with the adhesive and optionally after drying. Non-flexible substrates bonded to sheet-like, flexible substrates, obtainable by a process according to one of the preceding claims. Flexible substrates of at least one flexible carrier and an adhesive coating, characterized in that the adhesive coating contains 0.0001 to 0.1 mol of carbodiimide groups per 100 g of adhesive, calculated on solvent-free adhesive, wherein the carbodiimide-containing compounds of the adhesive have urea groups and these urea groups can be prepared by hydrolysis of isocyanate-containing carbodiimide compounds or by reacting isocyanate-containing carbodiimide compounds with non-polymeric, acid group-free amine compounds. Flexible substrates according to the preceding claim, characterized in that the urea-containing carbodiimide compounds can be prepared by hydrolysis of isocyanate carbodiimide compounds, wherein the isocyanate carbodiimide compounds are emulsified in water and stirred until no more isocyanate groups are detectable.