Use of dispersion adhesives for foam bonding

Abstract

The invention relates to the use of an aqueous dispersion comprising at least one polyurethane-polyurea polymer, the polyurethane-polyurea polymer being formed from (a) at least one difunctional polyester polyol having a number average molecular weight of 400 to 5000 g / mol, (b) at least one difunctional polyol component having a number average molecular weight of 62 to 399 g / mol, (c) at least one diisocyanate, and (d) at least one chain extender optionally having at least one ionic group, for bonding at least two substrates by applying the aqueous dispersion to at least one substrate to be bonded, then drying the dispersion present on the at least one substrate to obtain at least one adhesive layer and contacting the at least one adhesive layer with another substrate or with an adhesive layer present on another substrate at a pressure of 0.1 to 5 bar (a) and a temperature below 40° C., wherein the polyurethane-polyurea polymer after drying has a glass transition temperature Tg of 65 to 10° C. and a melting temperature of 40 to 80° C., to a corresponding method for bonding at least two substrates, and to an adhesive composite obtained in this way comprising at least two substrates and an adhesive layer present between each of the two substrates.

Description

[0001] The present invention relates to the use of an aqueous dispersion comprising at least one polyurethane-polyurea polymer, which is formed from (a) at least one difunctional polyester polyol having a number average molecular weight of 400 to 5000 g / mol, (b) at least one difunctional polyol component having a number average molecular weight of 62 to 399 g / mol, (c) at least one diisocyanate, and (d) at least one chain extender, which optionally contains at least one ionic group, for bonding at least two substrates by applying the aqueous dispersion to at least one substrate to be bonded, then drying the dispersion present on the at least one substrate and contacting the at least one adhesive layer with the other substrate or with the adhesive layer present on the other substrate at a pressure of 0.1 to 10 bar (a) and a temperature below 40° C., wherein the dried polyurethane-polyurea polymer has a glass transition temperature Tg of −65 to 10° C. and a melting temperature of 40 to 80° C., to a corresponding method for bonding at least two substrates, and to an adhesive composite obtained in this way, comprising at least two substrates and an adhesive layer present between each of the two substrates.

[0002] When foam substrates are bonded to other substrates, for example in foam-foam, foam-wood and foam-plastic combinations, polychloroprene dispersion adhesives are mainly used according to the spray congealing method. In this method, the adhesive and the coagulant are separately delivered to the spray gun, mixed and coagulated in the spray jet. Since the mixing only takes place in the spray jet, there is no need to consider the pot life. In addition, the coagulated adhesive remains on the surface of the substrate to be bonded and does not diffuse or only diffuses to a small extent into the pore structure of the foam substrate. High initial strength, sufficiently long open time and good heat resistance are usually achieved.

[0003] Important areas of application for this technology are the manufacture of mattresses and seating furniture. Chlorine-free alternatives to polychloroprene dispersion adhesives are in demand, especially in the Scandinavian countries, in order to be able to meet the requirements of, for example, the Nordic Ecolabel. In addition, they should be characterized by high initial strength and a sufficiently long open time.

[0004] Adhesives based on waterborne polyurethane dispersions are already used worldwide for demanding industrial applications, for example in shoemaking, bonding of automotive interior components, lamination of films or bonding of textile substrates.

[0005] When using polyurethane dispersions to bond substrates, the process is often carried out according to the thermal activation method. In this method, the dispersion is applied to the substrate and, after complete evaporation of the water, activated by heating (for example with infrared radiators) and converted into a bondable state. The temperature at which the adhesive film becomes viscous is called the activation temperature. Here, bonding occurs at temperatures and pressures above the melting temperature, so it is desirable that the substrate has a high thermal stability under the high pressures required for successful bonding. The resulting bonded seams are also characterized by high strength and rigidity, so that there has been no description to date of using polyurethane dispersions to bond flexible foam substrates that are irreversibly deformed at higher activation temperatures. In addition, according to the common methods, hard, continuous bonded seams are usually obtained, which in some cases greatly impair the comfort of flexible foams.

[0006] However, when using polyurethane dispersions or polyurethane-polyurea dispersions, it is also possible to work according to the wet bonding method, i.e. bonding is carried out immediately after the adhesive has been applied. The parts to be connected need to be fixed mechanically until the adhesive has set. This method is often used for bonding wood or textile substrates.

[0007] Both classical heat-activated and wet bonding methods are not very suitable for bonding foam substrates. In particular, the slow evaporation of water requires long waiting times or corresponding drying systems between the application of the adhesive and the bonding process. In addition, a considerable part of the adhesive can diffuse into the pores of the foam substrate before or during drying and is then no longer available for the actual bonding.

[0008] The adhesives based on aqueous polyurethane dispersions that are established on the market are generally not suitable for use in a spray application method, because they either do not set quickly enough, do not have sufficient initial strength or, due to the crystallinity of the polymer, form very hard bonded seams, which is unacceptable in particular for mattress production. The open time, i.e. the time interval between application of the adhesive until the joining parts are joined and a sufficiently good adhesive connection is obtained, is generally only one minute. However, many bonding processes require a time interval of at least twice this length.

[0009] WO 2013 / 053786 A1 describes aqueous polyurethane dispersions whose polymers have a melting temperature of 30° C. to 50° C., determined by dynamic differential thermal analysis at a heating rate of 20 K / min in accordance with DIN 65467, wherein the polymers have two differently crystallizing polyester polyols in a predetermined quantitative ratio. These polyurethane dispersions are primarily suitable as cold contact adhesives, but can also be used by means of the spray congealing process. However, the green strengths achievable thereby are insufficient for most foam adhesive applications.

[0010] BASF SE D DS 3548 provides an epoxy resin-modified polyurethane dispersion which is said to be particularly suitable for the spray congealing process. The basis of the epoxy resin used here is bisphenol A diglycidyl ether. Since bisphenol A and subsequent products prepared therefrom are considered extremely critical, especially by the end consumer, with regard to possible endocrine effects and are therefore generally not accepted, there is a need for adhesives and products which do not contain bisphenol A.

[0011] From EP 2090603 A2 an aqueous dispersion is known which comprises a mixture consisting of

[0012] A) an aqueous polyurethane dispersion or polyurethane-urea dispersion comprising I. a polymer A) formed from I(i) at least one difunctional aliphatic polyester polyol having a molecular weight of 400 to 5000 g / mol, I(ii) at least one mixture of hexamethylene diisocyanate (HDI) and 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), and I(iii) at least one mixture of two or more amine chain extenders, at least one of which carries an ionic group, and the polymer A) is partially crystalline or crystalline after drying and has a temperature range of -65 to -40°C. A) is an aqueous polyurethane dispersion or polyurethane-urea dispersion different from A), comprising a polymer B) formed from: II (i) at least one difunctional aromatic polyester polyol having a molecular weight of 400 to 5000 g / mol, II (ii) at least one difunctional polyol component having a molecular weight of 62 to 399 g / mol, II (iii) at least one aliphatic diisocyanate and II (iv) at least one amine chain extender having ionic groups, wherein the polymer B) is amorphous after drying and has a glass transition at a glass transition temperature Tg of -15 to +10°C.

[0013] Combinations of these aqueous polyurethane dispersions or polyurethane-polyurea dispersions are suitable as adhesives both by thermally activated processes and by wet bonding processes and exhibit better bond strengths than their individual components.

[0014] The object of the present invention is therefore to provide an alternative to chlorine- and bisphenol A-free polychloroprene dispersion adhesives for bonding foam substrates by spray application, which does not have the disadvantages of the prior art and is characterized in particular by high initial strength and a sufficiently long open time, preferably at least 2 minutes. According to the invention, this object is achieved by using an aqueous dispersion comprising at least one polyurethane-polyurea polymer, the polyurethane-polyurea polymer being formed from

[0015] (a) at least one difunctional polyester polyol having a number average molecular weight of 400 to 5000 g / mol,

[0016] (b) at least one difunctional polyol component having a number average molecular weight of 62 to 399 g / mol,

[0017] (c) at least one diisocyanate, and

[0018] (d) at least one chain extender, which optionally contains at least one ionic group

[0019] for bonding at least two substrates by applying the aqueous dispersion to at least one substrate to be bonded, then drying the dispersion present on the at least one substrate to obtain at least one adhesive layer and bringing the at least one adhesive layer into contact with another substrate or with an adhesive layer present on another substrate at a pressure of 0.1 to 5 bar(a) and a temperature below 40° C.,

[0020] The polyurethane-polyurea polymer after drying has a glass transition temperature Tg of -65 to 10°C and a melting temperature of 40 to 80°C.

[0021] According to the present invention, the object is also achieved by a method for connecting at least two substrates, the method comprising at least the following steps:

[0022] (A) providing an aqueous dispersion comprising at least one polyurethane-polyurea polymer having a glass transition temperature Tg of -65 to 10°C and a melting temperature of 40 to 80°C after drying, which is formed as follows:

[0023] (a) at least one difunctional polyester polyol having a number average molecular weight of 400 to 5000 g / mol,

[0024] (b) at least one difunctional polyol component having a number average molecular weight of 62 to 399 g / mol,

[0025] (c) at least one diisocyanate, and

[0026] (d) at least one chain extender, which optionally contains at least one ionic group,

[0027] (B) applying the aqueous dispersion from step (A) to at least one substrate,

[0028] (C) drying the existing at least one dispersion from step (B) to obtain at least one adhesive layer, and

[0029] (D) contacting the at least one adhesive layer with another substrate or an adhesive layer present on another substrate at a pressure of 0.1 to 10 bar (a) and a temperature below 40°C.

[0030] The use according to the invention and the method according to the invention are described in detail below.

[0031] The polyurethane-polyurea polymers used according to the invention are generally formed from

[0032] (a) at least one difunctional polyester polyol having a number average molecular weight of 400 to 5000 g / mol,

[0033] (b) at least one difunctional polyol component having a number average molecular weight of 62 to 399 g / mol,

[0034] (c) at least one diisocyanate, and

[0035] (d) at least one chain extender, optionally containing at least one ionic group.

[0036] Component (a):

[0037] The polyurethane-polyurea polymers used according to the invention comprise as component (a) at least one difunctional polyester polyol having a number-average molecular weight of 400 to 5000 g / mol.

[0038] In a preferred embodiment, the polyurethane-polyurea polymer used according to the invention comprises as component (a) a bifunctional polyester polyol with a number-average molecular weight of 400 to 5000 g / mol. This means that no mixture of different polyester polyols is used, but only one polyester polyol is used as component (a). Within the scope of the present invention, "one polyester polyol" means that the polyester polyols used are identical in terms of the monomers present, the quantitative ratio of the monomers, etc. The person skilled in the art knows that the molecular weights of the individual polyester polyol molecules present can be different within the ranges given, but can still be described as one polyester polyol.

[0039] The number average molecular weight of the difunctional polyester polyol (a) is preferably 1500 to 3000 g / mol, particularly preferably 1800 to 2500 g / mol, very particularly preferably 1900 to 2300 g / mol. It is known to those skilled in the art that the number average molecular weight of a polymer diol can be calculated, for example, from the OH number (hydroxyl number). In the case of monomeric polyols, the molecular weight corresponds to the absolute molecular weight in Daltons. The OH number is determined in tetrahydrofuran according to DIN EN ISO 4629-2.

[0040] Aliphatic and / or aromatic difunctional polyester polyols can be used according to the invention.

[0041] Suitable difunctional aliphatic polyester polyols (a) according to the invention preferably include linear polyester diols, such as can be prepared in a known manner from aliphatic or cycloaliphatic dicarboxylic acids, such as succinic acid, methylsuccinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, nonanedicarboxylic acid, decanedicarboxylic acid, tetrahydrophthalic acid, hexahydrophthalic acid, cyclohexanedicarboxylic acid, maleic acid, fumaric acid, malonic acid or mixtures thereof, and polyols. The polyols are ethylene glycol, di-, tri-, tetraethylene glycol, 1,2-propylene glycol, di-, tri-, tetrapropylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propylene glycol, 1,4-dihydroxycyclohexane, 1,4-dihydroxymethylcyclohexane, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol or mixtures thereof. Instead of free polycarboxylic acids, corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols or mixtures thereof can also be used to prepare polyesters.

[0042] According to the invention, component (a) is preferably a difunctional aliphatic polyester polyol based on succinic acid, methylsuccinic acid, glutaric acid, adipic acid or maleic acid and 1,3-propanediol, 1,4-butanediol or 1,6-hexanediol.

[0043] Particularly preferred as component (a) are difunctional aliphatic polyester polyols based on adipic acid and 1,4-butanediol or 1,6-hexanediol.

[0044] As component (a), very particular preference is given to difunctional aliphatic polyester polyols based on adipic acid and 1,4-butanediol.

[0045] In a specific embodiment, polyester polyols based on ε-caprolactone or its derivatives and copolymers containing ε-caprolactone or its derivatives may be used.

[0046] The number average molecular weight of the difunctional aliphatic polyester polyol (a) is generally from 400 to 5000 g / mol, preferably from 1500 to 3000 g / mol, particularly preferably from 1900 to 2500 g / mol, very particularly preferably from 2100 to 2300 g / mol.

[0047] It is known to the person skilled in the art that the number-average molecular weight of a polymer diol can be calculated, for example, from the OH number (hydroxyl number). In the case of monomeric polyols, the molecular weight corresponds to the absolute molecular weight in Daltons. The OH number is determined in tetrahydrofuran according to DIN EN ISO 4629-2.

[0048] Suitable difunctional aromatic polyester polyols (a) include, in particular, linear polyester diols, such as can be prepared in a known manner from aromatic dicarboxylic acids, for example terephthalic acid, isophthalic acid or phthalic acid and their anhydrides, for example phthalic anhydride, and polyols, for example ethylene glycol, di-, tri-, tetraethylene glycol, 1,2-propylene glycol, di-, tri-, tetrapropylene glycol, 1,3-propylene glycol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propanediol, 1,4-dihydroxycyclohexane, 1,4-dihydroxymethylcyclohexane, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol or mixtures thereof.

[0049] Preference is given to difunctional aromatic polyester polyols (a) based on phthalic acid, phthalic anhydride and 1,4-butanediol or 1,6-hexanediol.

[0050] Particular preference is given to difunctional aromatic polyester polyols (a) based on phthalic acid or phthalic anhydride and 1,6-hexanediol.

[0051] The number average molecular weight of the difunctional aromatic polyester polyol (a) is from 400 to 5000 g / mol, preferably from 1500 to 3000 g / mol, particularly preferably from 1800 to 2300 g / mol, very particularly preferably from 1900 to 2100 g / mol.

[0052] It is known to the person skilled in the art that the number-average molecular weight of a polymer diol can be calculated, for example, from the OH number (hydroxyl number). In the case of monomeric polyols, the molecular weight corresponds to the absolute molecular weight in Daltons. The OH number is determined in tetrahydrofuran according to DIN EN ISO 4629-2.

[0053] Component (b):

[0054] The polyurethane-polyurea polymers used according to the invention comprise as component (b) at least one difunctional polyol component having a number average molecular weight of 62 to 399 g / mol.

[0055] Suitable difunctional polyol components with a molecular weight of 62 to 399 g / mol as component (b) are, for example, polyols such as ethylene glycol, di-, tri-, tetraethylene glycol, 1,2-propylene glycol, di-, tri-, tetrapropylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 1,5-pentanediol, 1,6-hexanediol, 2,2-dimethyl-1,3-propylene glycol, 1,4-dihydroxycyclohexane, 1,4-dimethylolcyclohexane, 1,8-octanediol, 1,10-decanediol, 1,12-dodecanediol or mixtures thereof. According to the invention, low molecular weight polyester diols such as bis-(hydroxyethyl) adipate and / or short-chain difunctional polyether polyols such as homopolymers, mixed polymers and graft polymers of ethylene oxide or propylene oxide are also used as component (b).

[0056] Particular preference is given to using 1,4-butanediol and / or 1,6-hexanediol, particularly preferably 1,6-hexanediol, as component (b).

[0057] Component (c):

[0058] The polyurethane-polyurea polymers used according to the invention comprise at least one diisocyanate as component (c).

[0059] In general, all diisocyanates known to the person skilled in the art to be suitable can be used as the at least one diisocyanate (c). Component (c) is preferably selected from aliphatic, cycloaliphatic, araliphatic and aromatic diisocyanates.

[0060] According to the invention, aliphatic compounds having at least two free isocyanate groups per molecule can be used as component (c). Preference is given to using compounds of the general formula Y(NCO): 2 A diisocyanate wherein Y is a divalent aliphatic hydrocarbon group having 4 to 12 carbon atoms, a divalent alicyclic hydrocarbon group having 6 to 15 carbon atoms, a divalent aromatic aliphatic group having 8 to 22 carbon atoms, or a divalent aromatic group having 6 to 20 carbon atoms.

[0061] Examples of such diisocyanates which are preferably used are tetramethylene diisocyanate, methylpentamethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, 4,4′-diisocyanato-dicyclohexylmethane or 4,4′-diisocyanato-2,2-dicyclohexylpropane, 4,4′-diisocyanatodicyclohexylmethane (H12MDI), toluene-2,4-diisocyanate and / or toluene-2,6-diisocyanate (TDI), diphenylmethane-2,2′-diisocyanate, diphenylmethane-2,4′-diisocyanate and / or diphenylmethane-4,4′-diisocyanate (MDI) or mixtures thereof.

[0062] Particular preference is given to hexamethylene diisocyanate (HDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane (IPDI) and 4,4'-diisocyanato-dicyclohexyl-methane and mixtures thereof. However, the isocyanates are preferably used alone. Very particular preference is given to hexamethylene diisocyanate (HDI).

[0063] According to the invention, preference is given to using diisocyanates (c) selected from the group consisting of pentamethylene diisocyanate, hexamethylene diisocyanate (HDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI), 4,4'-diisocyanatodicyclohexylmethane (H12MDI), toluene-2,4-diisocyanate and / or toluene-2,6-diisocyanate (TDI), diphenylmethane-2,2'-diisocyanate, diphenylmethane-2,4'-diisocyanate and / or diphenylmethane-4,4'-diisocyanate (MDI) and mixtures thereof.

[0064] According to the invention, it is further preferred to use a mixture of hexamethylene diisocyanate (HDI) and 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (IPDI) as component (c). The molar ratio HDI:IPDI is further preferably 9:1 to 1:9, particularly preferably 3:1 to 1:3, very particularly preferably 2:1.

[0065] In a further particularly preferred embodiment, polyisocyanates based on H12MDI or on mixtures of H12MDI and HDI and / or IPDI can also be used as component (c).

[0066] In a further particularly preferred embodiment, it is also possible to use aromatic isocyanates such as TDI, MDI or mixtures of aromatic isocyanates such as TDI, MDI with aliphatic isocyanates, in particular those mentioned above, as component (c).

[0067] Component (d):

[0068] The polyurethane-polyurea polymers used according to the invention comprise, as component (d), at least one chain extender, optionally comprising at least one ionic group, preferably an amine chain extender.

[0069] In general, all chain extenders which are known to the person skilled in the art to be suitable and which optionally contain at least one ionic group can be used as component (d).

[0070] According to the invention, preference is given to using as component (d) an amine chain extender having at least one ionic group, in particular (d) a diamino compound which additionally carries sulfonate and / or carboxylate groups, particularly preferably a sodium or potassium salt selected from the group consisting of N-(2-aminoethyl)-2-aminoethanesulfonic acid, N-(3-aminopropyl)-2-aminoethanesulfonic acid, N-(3-aminopropyl)-3-aminopropanesulfonic acid, N-(2-aminoethyl)-3-aminopropanesulfonic acid, similar carboxylic acids and mixtures thereof.

[0071] Very particular preference is given to the sodium salt of N-(2-aminoethyl)-2-aminoethanesulfonic acid or a similar carboxylic acid as component (d), very particular preference to the sodium salt of N-(2-aminoethyl)-2-aminoethanesulfonic acid.

[0072] According to the present invention, the amine chain extender (d) having at least one ionic group can be used alone or together with other chain extenders. They are preferably used alone.

[0073] Other amine chain extenders within the scope of the present invention are, for example, monoamines, amino alcohols or diamines.

[0074] Monoamines suitable according to the invention are aliphatic and / or cycloaliphatic primary and / or secondary monoamines, such as ethylamine, diethylamine, the isomeric propylamine and butylamine, higher linear aliphatic monoamines and cycloaliphatic monoamines, such as cyclohexylamine.

[0075] Suitable amino alcohols according to the invention, i.e. compounds which contain an amino group and a hydroxyl group in one molecule, are, for example, ethanolamine, N-methylethanolamine, diethanolamine, 1,3-diamino-2-propanol, N-(2-hydroxyethyl)ethylenediamine, N,N-bis(2-hydroxyethyl)ethylenediamine or 2-propanolamine. Further examples of other amine chain extenders are monoamino compounds which additionally carry sulfonic acid groups and / or carboxyl groups, such as taurine, glycine or alanine.

[0076] Suitable diamines according to the invention are, for example, 1,2-ethylenediamine, 1,6-hexamethylenediamine, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane (isophoronediamine), piperazine, 1,4-diaminocyclohexane or bis-(4-aminocyclohexyl)methane. Also suitable are adipic acid dihydrazide, hydrazine and hydrazine hydrate. Instead of diamino compounds, polyamines such as diethylenetriamine can also be used as building blocks.

[0077] In one embodiment according to the invention, a mixture of two or more amine chain extenders is preferably used as component (d), wherein at least one amine chain extender carries at least one ionic group. Chain extenders in the sense of the present invention also refer to monoamines which lead to chain termination.

[0078] Particularly preferred ingredients of the mixture used as component (d) are diethanolamine, 1,2-ethylenediamine, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane (isophoronediamine), piperazine, N-(2-hydroxyethyl)ethylenediamine and the sodium salt of N-(2-aminoethyl)-2-aminoethanesulfonic acid / -carboxylic acid.

[0079] According to the invention, particular preference is given to using a mixture of diethanolamine and the sodium salt of N-(2-aminoethyl)-2-aminoethanesulfonic acid as component (d).

[0080] The polyurethane-polyurea polymer used according to the invention is partially crystalline after drying, ie it has at least one glass transition temperature Tg of -65 to 10° C., preferably -60 to -20° C., particularly preferably -55 to -30° C. and at least one melting point of 40 to 80° C.

[0081] In the context of the present invention, a polyurethane-polyurea polymer is particularly referred to as partially crystalline when it has a melting peak corresponding to a melting enthalpy of ≥5 J / g, preferably ≥10 J / g, particularly preferably ≥20 J / g, very particularly preferably ≥40 J / g in a DSC measurement in accordance with DIN 65467 at a heating rate of 20 K / min. The melting peak is caused by the melting of regular substructures in the polymer.

[0082] The polyurethane-polyurea polymers used according to the invention have a melting temperature of 40 to 80° C., preferably 40 to 70° C., particularly preferably 42 to 55° C. The first heating is evaluated in each case in order to also include slowly crystallizing polymers.

[0083] A polyurethane-polyurea polymer is designated as amorphous when it has no melting peak or only a melting peak with a melting enthalpy of ≤5 J / g, preferably ≤3 J / g, particularly preferably ≤1 J, on the first heating.

[0084] In a preferred embodiment of the invention, amorphous polyurethane-polyurea polymers are mixed with crystalline polyurethane-polyurea polymers. In these preferred mixtures, the proportion of crystalline polyurethane-polyurea polymers is preferably ≥5% by weight, particularly preferably ≥20% by weight, very particularly preferably ≥40% by weight, in each case based on the entire mixture.

[0085] The aqueous polyurethane-polyurea dispersions used according to the invention preferably have a solids content of 20 to 60% by weight, preferably 25 to 55% by weight, particularly preferably 30 to 50% by weight.

[0086] The aqueous dispersions used according to the invention comprising the above-described polyurethane-polyurea polymers and polymer mixtures according to the invention can generally be prepared by any method known to the person skilled in the art. It is preferably prepared by the acetone process. For this purpose, a prepolymer is preferably prepared from components (a) to (c), dissolved in acetone and chain extended with component (d). After dispersion with water, the acetone is preferably removed by distillation. The use and implementation of the acetone process is prior art and known to the person skilled in the art.

[0087] According to the invention, it is preferred that the aqueous polyurethane-polyurea dispersions contain no external emulsifiers.

[0088] In a further preferred embodiment, the aqueous dispersion according to the invention comprising at least one polyurethane-polyurea polymer may comprise further ingredients.

[0089] These are selected, for example, from oxidation stabilizers, hydrolysis stabilizers, organic and inorganic fillers, plasticizers, other dispersions containing polymers, such as PVC (polyvinyl chloride), PVA (polyvinyl acetate), EVA (polyethylene vinyl acetate), PAC (polyacrylate), CR (polychloroprene), PS (polystyrene), SBR (polystyrene butadiene), NBR (polyacrylonitrile) and mixtures thereof, tackifiers, pigments, silicone dispersions, isocyanates, blocked isocyanates and mixtures thereof, in order, for example, to adapt the properties of the dispersion to the requirements.

[0090] The proportion of further constituents optionally present is preferably up to 70% by weight and at least 0.01% by weight, particularly preferably up to 50% by weight, very particularly preferably up to 30% by weight, in each case based on the solids content of the entire formulation.

[0091] According to the invention, the aqueous dispersion comprising at least one polyurethane-polyurea polymer has a solids content of 20 to 70% by weight, preferably 25 to 60% by weight, particularly preferably 30 to 55% by weight.

[0092] When used according to the invention, the aqueous dispersions according to the invention can generally be applied to at least one existing substrate by all methods known to the person skilled in the art.

[0093] The aqueous dispersion according to the invention is preferably delivered by means of a spray gun, preferably by means of an airless spray gun or an air atomizing spray gun known to the person skilled in the art. Here, spraying is preferably carried out with atomizing air at a pressure of 0.1 to 5 bar (a). However, according to the invention, "airless" delivery is also possible, as described, for example, in WO 2015 / 137808.

[0094] According to the present invention, the aqueous dispersion is preferably prepared in an amount of 20 to 180 g / m 2 , particularly preferably 30 to 160 g / m2 , very particularly preferably 40 to 140 g / m 2 , particularly preferably 45 to 120 g / m 2 Apply at an application rate (wet).

[0095] According to the present invention, the aqueous dispersion is preferably prepared in an amount of 10 to 90 g / m 2 , particularly preferably 15 to 80 g / m 2 , very particularly preferably 20 to 60 g / m 2 The amount of application (solid) is applied.

[0096] According to the present invention, the application amount on the foam substrate is ≤150g / m 2 (wet), preferably ≤100g / m 2 (wet), particularly preferably ≤75g / m 2 (wet), very particularly preferably ≤50 g / m 2 (wet).

[0097] The viscosity of the aqueous dispersions used according to the invention is generally ≤1000 mPa*s, preferably ≤500 mPa*s, particularly preferably ≤200 mPa*s, very particularly preferably ≤100 mPa*s, particularly preferably ≤50 mPa*s. The viscosity of the aqueous dispersions used according to the invention is preferably at least 10 mPa*s. The viscosities mentioned are in each case measured at 23° C. with spindle L2 at 30 revolutions per minute in accordance with DIN 53019.

[0098] The combination of low application amount (wet), high surface tension and low viscosity of the aqueous dispersion according to the invention allows the aqueous dispersion to be applied, in particular, to discontinuous surface structures, preferably in the form of droplets and further preferably in the form of a continuous film which does not run off onto the substrate surface.

[0099] According to the invention, preference is given to using aqueous dispersions with a high surface tension of preferably ≥30 mN / m, particularly preferably ≥35 mN / m, very particularly ≥40 mN / m. The surface tension is measured in accordance with DIN 53593. In film-forming coating materials and adhesives, additives which significantly reduce the surface tension are usually added in order to achieve better film-forming properties, whereby, in particular in the case of porous bodies and aqueous dispersions with low viscosity, the inner surfaces of the objects are preferentially wetted due to capillary effects and surface effects, which is undesirable in the use according to the invention.

[0100] According to the invention, ≥30% by weight, particularly preferably ≥50% by weight, very particularly preferably ≥70% by weight of the at least one polyurethane-polyurea polymer is preferably present as solids on the surface after application and drying, based in each case on the weight of solids.

[0101] According to the invention, this means in particular that ≥30% by weight, preferably ≥50% by weight, particularly preferably ≥70% by weight, based in each case on the weight of the solids, of the at least one polyurethane-polyurea polymer are present on the substrate surface with a maximum penetration depth of up to 1 mm, preferably up to 0.5 mm, particularly preferably up to 0.2 mm. This preferred feature according to the invention makes it possible to achieve particularly effective adhesive yields and, moreover, soft and thin bonded seams compared to the prior art, even when using high-modulus crystalline polyurethane-polyurea polymers as adhesives.

[0102] According to the invention, application is preferably carried out by means of airless or air atomization in such a way that the surface tension of the aqueous dispersion to be atomized is sufficiently high that islands or droplets are formed on the substrate instead of a uniform film.

[0103] In one specific embodiment of the invention, the aqueous dispersion used according to the invention can be printed, for example by means of a digital printing method such as piezo printing, bubble jet printing or valve jet printing. With this embodiment, according to the invention, it is also possible, preferably without loss of material due to overspray, to apply an optimized adhesive pattern which is optimally matched to the respective connection problem, for example in terms of position, material and layer thickness application of the aqueous dispersion.

[0104] According to the invention, two substrates are preferably bonded to one another. In one embodiment of the invention, only one of the at least two substrates to be bonded to one another is applied with the aqueous dispersion and treated accordingly before the adhesive layer thus formed is brought into contact with the other substrate.

[0105] In another preferred embodiment of the invention, an aqueous dispersion comprising at least one polyurethane-polyurea polymer is applied to at least two, preferably two, ie two substrates to be bonded, in particular to at least two, preferably two, substrate surfaces.

[0106] According to the present invention, different substrate surfaces can be coated with different aqueous dispersions containing at least one polyurethane-polyurea polymer, ie, aqueous dispersions formed from different above-mentioned components, as required.

[0107] In contrast to the methods of the prior art, the contacting of the substrate surface coated with the adhesive layer with the surface to be bonded is preferably carried out after the sprayed or printed aqueous dispersion has dried almost completely. The water content of the adhesive layer is therefore preferably less than 20% by weight, preferably less than 10% by weight, particularly preferably less than 8% by weight, very particularly preferably less than 5% by weight, particularly preferably less than 3% by weight. The water content of the adhesive layer is determined here as the residual water content, in percent by weight, as the difference between the dry weight after application of the aqueous dispersion and drying in a forced air oven at 40° C. for 24 hours.

[0108] Drying of the aqueous dispersion to obtain the adhesive layer is preferably carried out at room temperature, but, depending on the application, can also be carried out by drying with the aid of hot air or, for example, IR radiation.

[0109] According to the invention, the bonding of the substrates is carried out by contacting the substrates at a temperature below the melting temperature of the at least one polyurethane-polyurea polymer used according to the invention, i.e. below 40° C., preferably below 35° C., particularly preferably below 30° C., very particularly preferably below 25° C.

[0110] According to the invention, after heating the aqueous dispersion on the substrate to one of the abovementioned temperatures, the surfaces to be bonded are contacted for a period of at least 5 seconds, preferably at least 30 seconds, very particularly preferably at least 2 minutes, preferably at least 1 second.

[0111] According to the invention, the bonding of the substrates is carried out by contacting the substrates at a pressure of 0.1 to 5 bar(a), preferably 0.2 to 3 bar(a), particularly preferably 0.25 to 2 bar(a), particularly preferably 0.3 to 1.5 bar(a).

[0112] According to the present invention, the substrates coated with the adhesive layer are usually contacted for a period of time of from 5 seconds to 120 minutes, preferably from 30 seconds to 60 minutes, particularly preferably from 2 minutes to 30 minutes.

[0113] According to the invention, generally all substrates known to the person skilled in the art can be bonded to one another or to one another. According to the invention, preference is given to using at least one substrate which is a foam substrate or a porous material, preferably with a bulk density of less than 200 g / l, particularly preferably less than 120 g / l, very particularly preferably less than 80 g / l.

[0114] Foam substrates are understood to mean substrates made of foam materials, wherein foam materials are generally artificial substances with a porous structure and low density. The foam materials that can be used according to the invention can be open-cell, closed-cell or mixed-cell, preferably open-cell or mixed-cell. Foam materials are divided into hard foams and soft foams according to their hardness. Almost all plastics are suitable for foaming.

[0115] In a preferred embodiment of the present invention, the one or more foam substrates comprise, preferably consist of, polyurethane and / or rubber, such as natural rubber (NR), styrene-butadiene rubber (SBR), ethylene-propylene-diene polymer (EPDM), nitrile rubber (NBR) or chloroprene rubber (CR).

[0116] In a particularly preferred embodiment of the present invention, the one or more foam substrates consist of polyurethane.

[0117] According to the invention, a foam or porous material can be bonded to another foam or porous material, wherein the two foam or porous materials can be identical or different. According to the invention, a foam or porous material can also be bonded to a non-porous material, which is selected, for example, from wood, paper, leather, textiles, cork, plastics, in particular thermoplastics, elastomers, thermosetting plastics, composite materials, such as polyvinyl chloride, polyurethane, polyvinyl acetate, ABS, rubber, polyethylene vinyl acetate, polycarbonate or polyolefins, such as filled or unfilled polypropylene, and combinations thereof.

[0118] In a preferred embodiment, the at least one polyurethane-polyurea polymer contained in the aqueous dispersion used according to the invention does not form a continuous film on the surface of foams or porous materials on contact which, contrary to the prior art, is immediately tacky in the wet state or adheres in the wet state by pressing and subsequent drying.

[0119] Since bonding is preferably carried out according to the invention only after the aqueous dispersion has dried on the substrate and activation (in particular by heating) can be carried out at any point in time and also separately from the drying process, no pot life needs to be taken into account. This property according to the invention has the advantage that the location of application of the aqueous dispersion can be separated from the location of activation and / or the location of production of the adhesive bond.

[0120] In a preferred embodiment according to the invention, only one of the two coated substrates has to be thermally activated. Bonding is then achieved by contacting one thermally activated substrate with another substrate which has been coated according to the invention but not thermally activated.

[0121] Another advantage of the invention is that the dry adhesive layer can be bonded to other substrates. Precisely in the field of foam bonding, in particular in the production of furniture, mattresses, etc., residual moisture or residual solvent content is a major problem when bonding with aqueous or solvent-based adhesives, which can be avoided by the invention, in particular when the manufactured product is packaged directly after bonding.

[0122] The bonds obtained according to the invention exhibit sufficient immediate strength, in particular until the material tears instantaneously.

[0123] The open time of the aqueous dispersions used according to the invention is preferably at least 2 minutes, particularly preferably at least 4 minutes, very particularly preferably at least 6 minutes, particularly preferably at least 8 minutes.

[0124] In particular when bonding foam to foam or foam to other substrate surfaces which have a three-dimensional structure and are therefore not flat, such as wood, metal or plastic, the bonds produced according to the invention are able to absorb the restoring forces of the foam without requiring a waiting time after thermal activation and in particular without requiring complete removal of the water.

[0125] According to the invention, the substrates to be bonded, in particular nonpolar substrates, can be subjected to a substrate surface pretreatment known to those skilled in the art before application of the aqueous dispersion, for example by application of a primer, flame treatment or corona treatment.

[0126] The invention can particularly preferably be used for bonding foam to foam, foam to wood, foam to various plastics or textiles to various other substrates.

[0127] The present invention also relates to a method for connecting at least two substrates, comprising at least the following steps:

[0128] (A) providing an aqueous dispersion comprising at least one polyurethane-polyurea polymer having a glass transition temperature Tg of -65 to 10°C and a melting temperature of 40 to 80°C after drying, formed from:

[0129] (a) at least one difunctional polyester polyol having a molecular weight of 400 to 5000 g / mol,

[0130] (b) at least one difunctional polyol component having a molecular weight of 62 to 399 g / mol,

[0131] (c) at least one diisocyanate, and

[0132] (d) at least one chain extender containing at least one ionic group,

[0133] (B) applying the aqueous dispersion from step (A) to at least one substrate,

[0134] (C) drying the existing at least one dispersion from step (B) to obtain at least one adhesive layer, and

[0135] (D) contacting at least one adhesive layer with another substrate or an adhesive layer present on another substrate at a pressure of 0.1 to 5 bar (a) and a temperature below 40°C.

[0136] What has been said regarding preferred embodiments and details with respect to the use according to the invention applies correspondingly to the method according to the invention.

[0137] In particular, adhesive composites can be obtained with the use according to the invention and with the method according to the invention. According to the invention, the adhesive composite comprises a substrate, an adhesive layer obtained according to the invention and another substrate. The two substrates can consist of the same or different materials. According to the definition, the substrate can also be a textile fabric. At least one substrate is preferably a foam substrate.

[0138] The present invention therefore also relates to an adhesive composite comprising at least two substrates and an adhesive layer obtainable according to the invention.

[0139] What has been said with regard to preferred embodiments and details with regard to the use according to the invention and the method according to the invention applies correspondingly to the adhesive composite according to the invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0140] Figure 1 The operation for evaluating the initial strength is shown. Example

[0141] The present invention will be described in more detail below with reference to the examples. The following methods and test methods are used herein:

[0142] A) Spray application method:

[0143] The adhesive dispersion is applied with a standard spray gun. Here, the adhesive dispersion is fed into the spray gun and applied to the substrate via a spray jet. After application to the substrate, the adhesive is dried in an oven at 60° C. for 20 minutes and then pressed after a predetermined time as described in B). The amount of adhesive applied varies according to requirements; the substrate is weighed on a precision balance without adhesive and immediately after application of the adhesive and after drying in a hot air oven, from which the wet and dry amounts applied are determined and given per square meter.

[0144] The exact setting of the spray gun is known in principle to the person skilled in the art and can be tailored to the individual case without difficulty and determined by simple preliminary experiments. By way of example, the following may be mentioned:

[0145] Adhesive component: delivery pressure 1.3 bar (a)

[0146] Atomizer air pressure: 2.8 bar (a)

[0147] Adhesive component aperture (nozzle): 1.0 mm

[0148] Applied weight: 50 to 200 g / m 2 (wet).

[0149] B) Determination of initial strength:

[0150] The test material used was PU foam ST5540 from STN Schaumstoff-Technik-Nürnberg GmbH, with dimensions of 10 cm x 5 cm x 3 cm and a bulk density of 40 kg / m 3 .

[0151] To evaluate the initial strength, the specimens were dried in a drying oven at 60 °C and immediately folded in the middle with a wooden stick and immediately passed through two steel rollers with a spacing of 10 mm (see Figure 1 ).

[0152] Figure 1 The reference numerals in the figures have the following meanings:

[0153] 1 Foam body

[0154] 2 Upper side of the foam body

[0155] 3 sticks

[0156] 4 Middle

[0157] 5 Test equipment

[0158] 6 Steel Rollers

[0159] 7 Tangent Spacing

[0160] 8 Threaded spindle

[0161] 9 Glue the seams.

[0162] If the specimen does not open despite the presence of restoring forces, the initial strength is sufficient. The results are classified as follows: Initial strength: good + / slightly open 0 / fully open -.

[0163] C) Determination of opening hours:

[0164] The test material used was ST 5540 PU foam from STN Schaumstoff-Technik-Nürnberg GmbH, with dimensions of 10 cm x 5 cm x 3 cm and a bulk density of 40 kg / m 3 To evaluate the open time, immediately after taking the specimen out of the hot air oven every 60 seconds or at given time intervals as required, the specimen is folded in the middle and joined together by light pressure with the palm of the hand. The beginning and end of the open time are indicated by the fact that the strength is no longer sufficient and the specimen opens due to the generated restoring force. The results are classified according to the following classification: Time (minutes): <1min - poor, ≥4min - satisfactory, ≥8min - good.

[0165] D) Determination of adhesive joint hardness:

[0166] After storage for 24 hours at room temperature, the bonded seams of the test specimens produced under B) were directly compared with reference specimens and evaluated sensory by touch. The reference specimens were produced using commercially available polychloroprene latexes of varying Shore A hardness (Covestro Deutschland AG). The bonded seam of the specimen obtained with C 84 (Shore A hardness of pure dry polymer = 88) was used as a reference for the hard bonded seam. The bonded seams of the specimens obtained from C 74 (Shore A hardness of pure dry polymer = 55) were used as reference for medium hardness bonded seams, while the bonded seams obtained from The bonded seams of the specimens obtained with C2372 (Shore A hardness of pure dry polymer = 40) were used as a reference for soft bonded seams. C products are in each case 200 g / m 2 Wet weight, equivalent to about 110g / m 2 The results were classified as follows: Soft + / Medium Hard 0 / Hard -.

[0167] E) Determination of the glass transition temperature, melting temperature and melting enthalpy by means of DSC:

[0168] The measuring principle of DSC (Differential Scanning Calorimetry) is based on heating a sample and an inert reference in the measuring cell of the calorimeter so that both always have the same temperature. Sample and reference are heated with the same regulated temperature / time program. The temperatures of sample and reference are measured, compared, and compensated for temperature differences due to physical or chemical changes in the sample morphology. The applied electrically compensated power is measured and converted into a measure of the thermal heat flow. Such morphological changes are the result of physical transitions (glass transition, melting, evaporation) and chemical changes (oxidation, cross-linking). Melting processes, evaporation and solid-solid transitions (glass transition) are endothermic in nature, while crystallization, oxidation and some chemical reactions (such as cross-linking) are exothermic.

[0169] The glass transition temperature, melting temperature and melting enthalpy were determined by differential scanning calorimetry (DSC) with a calorimeter Pyris Diamond DSC from Perkin-Elmer. For this purpose, the film was prepared by coating the corresponding dispersion with a wet film thickness of 100 μm onto a glass plate and dried in a drying oven at room temperature and 0% room humidity for 3 days. The DSC curve was then recorded under the following measuring conditions using 10 mg of sample material: rapid cooling to a starting temperature of -100°C, followed by the start of three heatings from -100°C to +150°C, a heating rate of 20 K / min, a cooling rate of 320 K / min, under a helium atmosphere and cooling with liquid nitrogen. The glass transition temperature corresponds to the temperature at the half-height of the glass transition, in which the third heating was evaluated. In order to determine the melting temperature and the melting enthalpy, the first heating was evaluated.

[0170] F) Raw materials:

[0171] A: U56, a crystalline polyurethane adhesive dispersion, glass transition temperature Tg -50°C, melting temperature Tm 49°C, was obtained from Covestro Deutschland GmbH and used as received.

[0172] B: U54, a crystalline polyurethane adhesive dispersion, glass transition temperature -51 °C, melting temperature 49 °C, was obtained from Covestro Deutschland GmbH and used as received.

[0173] C: U2682, a crystalline polyurethane adhesive dispersion, glass transition temperature Tg - 48°C, melting temperature 50°C, was obtained from Covestro Deutschland GmbH and used as received.

[0174] D: U42, an amorphous polyurethane adhesive dispersion, glass transition temperature -5.1 °C, was obtained from Covestro Deutschland GmbH and used as received.

[0175] E: U2643, an amorphous polyurethane adhesive dispersion, glass transition temperature -51 °C, was obtained from Covestro Deutschland GmbH and used as received.

[0176] Table 1: Results of Examples According to the Invention and Comparative Examples

[0177]

[0178]

[0179] V. Comparative Example.

Claims

1. Use of an aqueous dispersion comprising at least one polyurethane-polyurea polymer, the polyurethane-polyurea polymer being formed from the following components (a) at least one difunctional polyester polyol having a number average molecular weight of 400 to 5000 g / mol, (b) at least one difunctional polyol component having a number average molecular weight of 62 to 399 g / mol, (c) at least one diisocyanate, and (d) at least one chain extender, which optionally contains at least one ionic group, for bonding at least two substrates by applying the aqueous dispersion to at least one substrate to be bonded, then drying the dispersion present on the at least one substrate to obtain at least one adhesive layer and bringing the at least one adhesive layer into contact with the other substrate or with an adhesive layer present on the other substrate at an absolute pressure of 0.2 to 3 bar and a temperature below 40° C., It is characterized in that The polyurethane-polyurea polymer after drying has a glass transition temperature Tg of -65 to 10°C and a melting point of 40 to 80°C. wherein ≥ 30% by weight, in each case based on the weight of solids, of the at least one polyurethane-polyurea polymer are present on the substrate surface with a penetration depth of up to 1 mm, using a porous material as at least one substrate, The aqueous dispersion has a concentration of 20 to 180 g / m 2 Apply in the amount of wet form.

2. The use according to claim 1, characterized in that As component (a), difunctional aliphatic polyester polyols based on succinic acid, methylsuccinic acid, glutaric acid, adipic acid or maleic acid and 1,3-propylene glycol, 1,4-butylene glycol and / or 1,6-hexanediol are used.

3. The use according to claim 1, characterized in that As component (a), a difunctional aromatic polyester polyol (a) based on phthalic acid, phthalic anhydride and 1,4-butanediol and / or 1,6-hexanediol is used.

4. The use according to any one of claims 1 to 3, characterized in that As component (c) use is made of tetramethylene diisocyanate, methylpentamethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane, 4,4'-diisocyanato-dicyclohexylmethane or 4,4'-diisocyanato-2,2-dicyclohexylpropane, 4,4'-diisocyanato-dicyclohexylmethane, toluene-2,4-diisocyanate and / or toluene-2,6-diisocyanate, diphenylmethane-2,2'-diisocyanate, diphenylmethane-2,4'-diisocyanate and / or diphenylmethane-4,4'-diisocyanate or mixtures thereof.

5. The use according to any one of claims 1 to 3, characterized in that The aqueous polyurethane-polyurea dispersions used have a solids content of 20 to 60% by weight.

6. The use according to any one of claims 1 to 3, characterized in that ≥50% by weight, based in each case on the weight of solids, of the at least one polyurethane-polyurea polymer are present on the substrate surface with a penetration depth of up to 1 mm at most.

7. The use according to any one of claims 1 to 3, characterized in that ≥ 70% by weight, based in each case on the weight of solids, of the at least one polyurethane-polyurea polymer are present on the substrate surface with a penetration depth of up to 1 mm at most.

8. The use according to any one of claims 1 to 3, characterized in that ≥ 70% by weight, based in each case on the weight of solids, of the at least one polyurethane-polyurea polymer are present on the substrate surface with a penetration depth of up to a maximum of 0.5 mm.

9. The use according to any one of claims 1 to 3, characterized in that ≥ 70% by weight, based in each case on the weight of solids, of the at least one polyurethane-polyurea polymer are present on the substrate surface with a penetration depth of up to a maximum of 0.2 mm.

10. The use according to any one of claims 1 to 3, characterized in that The aqueous dispersion has a concentration of 10 to 90 g / m 2 Apply in an amount of solid form.

11. The use according to any one of claims 1 to 3, characterized in that The porous material is a foam substrate.

12. The use according to any one of claims 1 to 3, characterized in that The porous material has a bulk density of less than 200 g / l.

13. The use according to any one of claims 1 to 3, characterized in that The porous material has a bulk density of less than 120 g / l.

14. The use according to any one of claims 1 to 3, characterized in that The porous material has a bulk density of less than 80 g / l.

15. The use according to any one of claims 1 to 3, characterized in that As component (d), an amine chain extender having at least one ionic group is used.

16. A method for connecting at least two substrates, comprising at least the following steps: (A) providing an aqueous dispersion comprising at least one polyurethane-polyurea polymer having a glass transition temperature Tg of -65 to 10°C and a melting temperature of 40 to 80°C after drying, which is formed from the following components (a) at least one difunctional polyester polyol having a number average molecular weight of 400 to 5000 g / mol, (b) at least one difunctional polyol component having a number average molecular weight of 62 to 399 g / mol, (c) at least one diisocyanate, and (d) at least one chain extender, which optionally contains at least one ionic group, (B) applying the aqueous dispersion from step (A) to at least one substrate, (C) drying the existing at least one dispersion from step (B) to obtain at least one adhesive layer, and (D) contacting the at least one adhesive layer with another substrate or an adhesive layer present on another substrate at an absolute pressure of 0.2 to 3 bar and a temperature below 40° C., wherein ≥ 30% by weight, based in each case on the solids weight, of the at least one polyurethane-polyurea polymer are present on the substrate surface with a penetration depth of up to 1 mm, using a porous material as at least one substrate, The aqueous dispersion has a concentration of 20 to 180 g / m 2 Apply in the amount of wet form.

17. The method according to claim 16, characterized in that ≥50% by weight, based in each case on the weight of solids, of the at least one polyurethane-polyurea polymer are present on the substrate surface with a penetration depth of up to a maximum of 1 mm.

18. The method according to claim 16, characterized in that ≥ 70% by weight, based in each case on the weight of solids, of the at least one polyurethane-polyurea polymer are present on the substrate surface with a penetration depth of up to 1 mm at most.

19. The method according to claim 16, characterized in that ≥ 70% by weight, based in each case on the weight of solids, of the at least one polyurethane-polyurea polymer are present on the substrate surface with a penetration depth of up to a maximum of 0.5 mm.

20. The method according to claim 16, characterized in that ≥ 70% by weight, based in each case on the weight of solids, of the at least one polyurethane-polyurea polymer are present on the substrate surface with a penetration depth of up to a maximum of 0.2 mm.

21. The method according to claim 16, characterized in that The porous material is a foam substrate.

22. The method according to claim 16, characterized in that The porous material has a bulk density of less than 200 g / l.

23. The method according to claim 16, characterized in that The porous material has a bulk density of less than 120 g / l.

24. The method according to claim 16, characterized in that The porous material has a bulk density of less than 80 g / l.

25. The adhesive composite obtained by the use according to any one of claims 1 to 15 or the method according to any one of claims 16 to 24, comprising at least two substrates and an adhesive layer present between each two substrates.

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