De-bondable compact PU (Poly Urethane) material

Abstract

The invention relates to a method for producing polyurethanes having carboxyl groups, said method comprising the following steps: providing a polyol composition (PC) consisting essentially of the following components: at least one compound (a), at least one carboxyl group or derivative thereof and at least one functional group comprising an active hydrogen reactive with an isocyanate group; at least one polyol compound (b) having an average of 1.5 to 3.5 hydroxyl groups per molecule; optionally one or more additional active hydrogen compounds (c) different from compounds (a) and (b); optionally one or more additional additives free of active hydrogen; the polyol composition (PC) provided in step (i) is then brought into contact with at least one isocyanate composition (IC) comprising at least one isocyanate (I1) having on average at least 1.5 isocyanate groups wherein the NCO group content of the resulting product is in the range of 0.1 to 35 wt%. The invention also relates to the polyurethanes obtained in this method and to the use thereof as adhesives, as binders or as components for producing polyurethanes. According to another aspect, the invention relates to a method for producing a composite material comprising at least a first component (C1) and a second component (C2), comprising the following steps: providing the first component (C1) and the second component (C2), providing a polyurethane obtained or obtainable according to the method of the invention, and bonding the first component and the second component by means of the polyurethane according to the invention.

Description

[0001] The present invention relates to a method for producing a polyurethane having carboxyl groups, the method comprising the following steps: providing a polyol composition (PC) which consists essentially of the following components: at least one compound (a) which carries at least one carboxyl group or a derivative thereof and at least one functional group containing active hydrogen which is reactive toward isocyanate groups; at least one polyol compound (b) which has an average of 1.5 to 3.5 hydroxyl groups per molecule; optionally one or more additional active hydrogen compounds (c) which are different from compounds (a) and (b); optionally one or more additional additives which do not contain active hydrogen; and then contacting the polyol composition (PC) provided in step (i) with at least one isocyanate composition (IC) which contains at least one isocyanate (I1) having an average of at least 1.5 isocyanate groups, wherein the NCO group content of the resulting product is in the range of 0.1% to 35% by weight. The present invention also relates to the polyurethane obtained in the process and to its use as an adhesive, as a binder or as a component for the preparation of polyurethanes. According to another aspect, the present invention relates to a method for preparing a composite material comprising at least a first component (C1) and a second component (C2), the method comprising the following steps: providing a first component (C1) and a second component (C2), providing a polyurethane obtained or obtainable according to the method of the present invention, and bonding the first component and the second component with the aid of the polyurethane according to the present invention.

[0002] Many consumer products are made of multiple components of different materials that are bonded to each other by adhesives. Such bonded products are difficult to recycle, and it is difficult to reuse a single material because they must be debonded before reuse.

[0003] Consumer product manufacturers are increasingly demanding the concept of sustainability by increasing the recycling rate of used bonded articles. For example, high-performance sports shoes are often based on thermosetting polymers, such as thermoplastic polyurethanes, which are bonded to other materials, for example non-polyurethane materials, such as ethylene-vinyl acetate, polyester textiles or synthetic leather. The separation of the cross-linked polymers and the subsequent recycling of the separated cross-linked foams can also be carried out by glycolysis. The non-polyurethane materials must be removed after the life cycle of the article by an on-demand debonding mechanism, and then the thermosetting polymers, especially thermoplastic polyurethanes, are recycled and reused.

[0004] There is a similar need in other technical fields to release the bonding components of different materials so that different materials can be recycled separately, such as car seats or dashboards, dashboards, meat or cheese food packaging, etc. For example, WO2019 / 175151 A1 describes a method for making thermoplastic polyurethane from recycled polyurethane materials. The method requires debonding non-polyurethane materials from polyurethane materials. WO 2018 / 156689 describes debondable adhesives and their use for footwear manufacturing and debonding. Debonding is achieved by using carboxylic acids and their salts and by using microwave radiation.

[0005] In particular in the footwear industry there remains a need for improved methods that facilitate the recycling of shoe components. The problem on which the present invention is based is to provide a method for debonding bonded articles (e.g. shoes) made of different components in order to recycle the different components (e.g. upper material and sole) under mild conditions with relatively low energy consumption in a short cycle time. Under normal conditions of storage, use and cleaning, bonded articles should exhibit a high resistance to premature debonding. It is a challenge to provide a material that has a high bond strength during the regular use of the article, but which can be easily debonded as required within a short period of time under the stimulation of appropriate conditions for recycling purposes.

[0006] An object of the present invention is to provide a material which is suitable as an adhesive or for bonding two or more components and which allows the debonding of the corresponding product obtained. This also allows the reuse of the components without complete decomposition of the corresponding components.

[0007] According to the invention, this problem is solved by a process for producing a polyurethane having carboxyl groups, comprising the following steps:

[0008] (i) providing a polyol composition (PC) consisting essentially of the following components:

[0009] a) at least one compound (a) which carries at least one carboxyl group or a derivative thereof and at least one functional group comprising an active hydrogen which is reactive toward isocyanate groups;

[0010] b) at least one polyol compound (b) having an average of 1.5 to 3.5 hydroxyl groups per molecule;

[0011] c) optionally one or more additional active hydrogen compounds (c) different from compounds (a) and (b);

[0012] d) optionally one or more further additives not containing active hydrogen;

[0013] (ii) contacting the polyol composition (PC) provided in step (i) with at least one isocyanate composition (IC) comprising at least one isocyanate (I1) having an average of at least 1.5 isocyanate groups,

[0014] The NCO group content of the obtained product is in the range of 0.1% to 35%.

[0015] Surprisingly, it has been found that according to the invention, stable polyurethanes with carboxyl groups can be provided, wherein the NCO group content of the resulting product is in the range of 0.1% to 35% by weight, in particular in the range of 0.5% to 30% by weight. The resulting polyurethanes are particularly suitable as binders or adhesives.

[0016] Preferably, the NCO group content of the obtained product is in the range of 1% to 25% by weight, in particular in the range of 1.5% to 20% by weight, more preferably in the range of 3% to 15% by weight, particularly preferably in the range of 4% to 15% by weight.

[0017] Surprisingly, it has been found that the polymers according to the invention with an NCO content have good properties, such as suitable viscosity with NCO and COOH groups in the same molecule. Surprisingly, these prepolymers can be isolated, are storage-stable and can be used for special applications.

[0018] According to the invention, the process comprises steps (i) and (ii). According to step (i), a polyol composition (PC) is provided which consists essentially of compounds (a) and (b) and may also contain further compounds.

[0019] The polyol composition (PC) comprises at least one compound (a) which carries at least one carboxyl group or a derivative thereof and at least one functional group comprising an active hydrogen which is reactive toward isocyanate groups.

[0020] According to the present invention, at least one carboxyl group or its derivative includes a carboxyl group or its salt and a derivative that can be converted into a carboxyl group using mild conditions, such as an ester or anhydride. In the context of the present invention, a suitable derivative can be an ester or anhydride that can be converted into a carboxyl group in a hydrolysis reaction at a temperature in the range of more than 25°C, for example 25°C to 60°C.

[0021] The term "active hydrogen" refers to a compound having at least one functional group that is capable of reacting with an isocyanate group in an addition reaction, thereby forming a chemical bond between the carbon atom of the isocyanate group and one of the atoms of the functional group. These functional groups are also referred to as "active hydrogen functional groups" or "isocyanate reactive groups". Typical active hydrogen functional groups of active hydrogen compounds are hydroxyl groups (OH), thiol groups (SH), primary amino groups (NH2) and secondary amino groups (NH). The above functional groups will react with isocyanate groups to form carbamate, urea or thiocarbamate groups, respectively.

[0022] The polyol composition (PC) further comprises at least one polyol compound (b) having an average of 1.5 to 3.5 hydroxyl groups per molecule, preferably an average of 1.5 to 3 hydroxyl groups per molecule.

[0023] The composition may also contain additional components. The composition may, for example, contain one or more additional active hydrogen compounds (c) different from compounds (a) and (b). In addition, the composition may optionally contain one or more additional additives that do not contain active hydrogen as component (d).

[0024] The compound (a) carries at least one carboxyl group or a derivative thereof and at least one functional group comprising an active hydrogen which is reactive toward isocyanate groups. Suitable compounds are known in principle to those skilled in the art.

[0025] Typically, in the context of the present invention, compound (a) is an aliphatic compound and may, for example, have one or two functional groups containing active hydrogens reactive toward isocyanate groups, such as OH groups, NH groups or SH groups. In the context of the present invention, compound (a) may also have one OH group and one NH group. Preferably, compound (a) has at least one carboxyl group or a derivative thereof and at least one OH group.

[0026] According to another embodiment, the present invention also relates to a process as disclosed above, wherein component (a) is selected from the group consisting of compounds having one carboxyl group and one or two functional groups selected from the group consisting of SH, NH and OH groups. According to another embodiment, the present invention also relates to a process as disclosed above, wherein component (a) is selected from the group consisting of compounds having one carboxyl group and two OH groups.

[0027] Suitable as compound (a) are, for example, aliphatic compounds with 2 OH groups and at least 1 (e.g. 1 or 2) carboxyl groups or derivatives thereof. Their molecular weight is generally in the range of 120 g / mol to 400 g / mol. Compound (a) can, for example, be selected from the group consisting of bis(hydroxymethyl)alkanoic acid, in particular the group consisting of 2,2-bis(hydroxymethyl)-C2-C8-alkanoic acid, such as 2,2-bis(hydroxymethyl)propionic acid (hereinafter also referred to as DMPA), 2,2-bis(hydroxymethyl)butanoic acid (hereinafter also referred to as DMBA), 2,2-bis(hydroxymethyl)valeric acid and 2,2-bis(hydroxymethyl)hexanoic acid. Specifically, compound a) is selected from the group consisting of 2,2-bis(hydroxymethyl)propionic acid and 2,2-bis(hydroxymethyl)butanoic acid and mixtures thereof.

[0028] Depending on the molecular weight of compound (a), the relative amount of compound (a) in the polyol composition (PC) is generally in the range of 3 to 50 wt.-%, in particular in the range of 4 to 45 wt.-%, especially in the range of 5 to 40 wt.-%, based on the total weight of the mixture provided in step (i).

[0029] According to another embodiment, the present invention also relates to the process as disclosed above, wherein the content of component (a) in the polyol composition is in the range of 3 wt. % to 50 wt. %.

[0030] The mixture provided in step (i) also comprises at least one polyol b) having an average of 1.5 to 3.5, in particular an average of 1.8 to 3.0, hydroxyl groups per molecule (also referred to as "average OH functionality"). The average OH functionality refers to the average number of hydroxyl groups possessed by the molecules of the polymer polyol.

[0031] The relative amount of compound (b) in the polyol composition is generally in the range of 50% to 97% by weight, particularly in the range of 60% to 97% by weight or 70% to 97% by weight, especially in the range of 75% to 97% by weight or 80% to 97% by weight, based on the total weight of the mixture provided in step (i).

[0032] Unless otherwise stated, the OH number of the polyol component is generally in the range of 6 mg KOH / g to 300 mg KOH / g, in particular in the range of 10 mg KOH / g to 200 mg KOH / g, especially in the range of 15 mg KOH / g to 180 mg KOH / g, in particular in the range of 35 mg KOH / g to 150 mg KOH / g, determined to EN ISO 4629-1:2016.

[0033] In principle, any polyol conventionally used for preparing polyurethanes can be used as polyol b). The type of polyol is less important and may depend on the desired purpose of the application. Suitable polyol compounds b) are polyester polyols, specifically including aliphatic polyester polyols and aliphatic aromatic polyester polyols, polyester carbonate polyols, polyether ester polyols, aliphatic polycarbonate polyols, polyacrylate polyols, polyolefin polyols, aliphatic polyether alcohols and mixtures thereof. In a preferred embodiment group, polyol b) is selected from polyester polyols, in particular aliphatic polyester polyols and aliphatic aromatic polyester polyols, aliphatic polycarbonate polyols, aliphatic polyether alcohols and mixtures thereof. Specifically, compound b) comprises polyester polyols and / or aliphatic polyether polyols as described herein. In particular, compound b) is selected from polyester polyols, aliphatic polyether polyols and combinations thereof.

[0034] According to another embodiment, the present invention also relates to the process as disclosed above, wherein the polyol (b) is selected from the group consisting of polyester polyols and polyether polyols.

[0035] According to another embodiment, the present invention also relates to a process as disclosed above, wherein the polyol (b) has an average molecular weight of less than 10000 g / mol. The molecular weight is determined according to DIN 55672-1:2016-03, and unlike the DIN standard, THF is used as solvent.

[0036] Suitable polyesterols as polyols b) are in particular aliphatic polyesterols and aliphatic / aromatic polyesterols, ie polyesterols based on a dicarboxylic acid component selected from aliphatic dicarboxylic acids, cycloaliphatic dicarboxylic acids, aromatic dicarboxylic acids and combinations thereof and a diol component selected from aliphatic diols, cycloaliphatic diols and polyether polyols.

[0037] Aliphatic diols suitable for preparing polyester polyols generally have 2 to 20 carbon atoms, in particular 3 to 10 carbon atoms. Examples of aliphatic diols are ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, 2,3-butanediol, 1,2-pentanediol, 1,3-pentanediol, 1,4-pentanediol, 1,5-pentanediol, 2,3-pentanediol, 2,4-pentanediol, 1,2-hexanediol, 1,3-hexanediol, 1,4-hexanediol, 1,5-hexanediol, 1,6-hexanediol, 2,5-hexanediol, 1,2-heptanediol, 1,7-heptanediol, 1,8-octanediol, 1,2-octanediol, 1,9-nonanediol, 1,2-decanediol, 1,10-decanediol, 1,2-dodecanediol, 1,12-dodecanediol, 1,5-hexadiene-3,4-diol, neopentyl glycol (2,2-dimethylpropane-1,3-diol), 2,2-diethylpropane-1,3-diol, 2-methyl-2-ethylpropane-1,3-diol, 2-methyl-2,4-pentanediol, 2,4-dimethyl-2,4-pentanediol, 2-ethyl-1,3-hexanediol, 2,5-dimethyl-2,5-hexanediol, 2,2,4-trimethyl-1,3-pentanediol, pinacol, diethylene glycol, triethylene glycol, dipropylene glycol and tripropylene glycol.

[0038] Suitable cycloaliphatic diols for preparing polyester polyols generally have 4 to 20 carbon atoms, in particular 5 to 10 carbon atoms. Examples of cycloaliphatic diols are cyclopentanediol, cyclohexane-1,4-diol, cyclohexane-1,2-dimethanol, cyclohexane-1,3-dimethanol, cyclohexane-1,4-dimethanol and 2,2,4,4-tetramethylcyclobutane-1,3-diol. Suitable diols for preparing polyester polyols are also polyether diols, in particular polyethylene glycol HO(CH2CH2O)nH, higher polypropylene glycol HO(CH[CH3]CH2O)nH, where n is an integer and n≥4, for example 4 to 20; polyethylene glycol-polypropylene glycol, more particularly those having 4 to 20 repeating units, the sequence of ethylene oxide and propylene oxide units can be block or random; polybutylene glycol, more particularly those having 4 to 20 repeating units; and poly-1,3-propylene glycol, more particularly those having 4 to 20 repeating units.

[0039] Preferred dicarboxylic acids for preparing the polyester polyols are aromatic dicarboxylic acids, such as phthalic acid, isophthalic acid and terephthalic acid; cycloaliphatic dicarboxylic acids, preferably having 8 to 12 carbon atoms, such as tetrahydrophthalic acid, hexahydrophthalic acid, cyclohexanedicarboxylic acid; aliphatic dicarboxylic acids, preferably having 3 to 40 carbon atoms, such as malonic acid, succinic acid, 2-methylsuccinic acid, glutaric acid, 2-methylglutaric acid, 3-methylglutaric acid, α-ketoglutaric acid, adipic acid, pimelic acid, azelaic acid, sebacic acid, tridecanedioic acid, fumaric acid, 2,2-dimethylglutaric acid, suberic acid, diglycolic acid, oxaloacetic acid, glutamic acid, aspartic acid, itaconic acid and maleic acid; and dimerized fatty acids, such as the dimerized fatty acids of octadecadienoic acid or those obtained by dimerization of other polyunsaturated fatty acids or fatty acid mixtures [CAS 61788-89-4].

[0040] The dicarboxylic acids used for preparing the polyester polyols can be free acids or their ester-forming derivatives. Derivatives are preferably understood to be the corresponding anhydrides; mono- and di-alkyl esters, preferably mono- and di-C1-C4-alkyl esters, more preferably mono- and dimethyl esters; and the corresponding mono- and diethyl esters; also mono- and divinyl esters; and mixed esters, examples being mixed esters with different C1-C4-alkyl components.

[0041] Among the polyester polyols, polyester polyols based on a diol component selected from the group consisting of butanediol, neopentyl glycol, hexanediol, ethylene glycol, diethylene glycol and mixtures thereof and a dicarboxylic acid component selected from the group consisting of adipic acid, phthalic acid, isophthalic acid and combinations thereof are preferred. Polyester polyols based on butanediol and / or neopentyl glycol and / or hexanediol and adipic acid and / or phthalic acid and / or isophthalic acid are particularly preferred.

[0042] Polyester polyols suitable as polyol b) also include polylactones, in particular poly-C4-C12-lactones, especially polycaprolactone (PCL). Polylactones are aliphatic polyesters obtainable by ring-opening polymerization of lactones, in particular C4-C12-lactones, in particular ε-caprolactone (ε-caprolactone). Polycaprolactones have repeating monomer units of the general formula (1) [-O-CHR-(CH2)m-CO-], where m is 4 to 10, in the case of caprolactone m=4, and R is hydrogen. In the context of the present invention, the term polycaprolactone is understood to refer to both homopolymers of ε-caprolactone and copolymers of ε-caprolactone. Suitable copolymers are, for example, copolymers of ε-caprolactone with monomers selected from the group consisting of lactic acid, lactide, glycolic acid and glycolide. Polyester polyols are common components, for example, which can be obtained from Ullmanns En- der technischen Chemie [Ullmann's Encyclopedia of Industrial Chemistry], 4th edition, volume 19, pages 62 to 65.

[0043] Aliphatic polyether polyols suitable as polyols b) are, for example, polyaddition products of C2-C4-alkylene oxides such as ethylene oxide, propylene oxide, 1,2-butylene oxide, 2,3-butylene oxide or 2-methylpropylene oxide. Further suitable polymeric polyols b) are aliphatic polyether polyols obtainable by condensation of polyhydric aliphatic alcohols, aliphatic polyether polyols obtained by alkoxylation of aliphatic polyols, amines and amino alcohols. Suitable polyols include ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,4-butylene glycol, neopentyl glycol, 1,6-hexanediol, trimethylolpropane, glycerol, pentaerythritol, triethanolamine (=tris(2-hydroxyethyl)amine), sorbitol or mixtures of these. Suitable polyether alcohols generally have an OH functionality in the range from 1.5 to 3.0, in particular in the range from 1.8 to 2.5. Suitable polyether alcohols preferably have an OH number in the range of 20 mg KOH / g to 300 mg KOH / g, in particular in the range of 30 mg KOH / g to 250 mg KOH / g. In the context of the present invention, the OH number is measured according to EN ISO 4629-1:2016, unless otherwise stated.

[0044] Typically, they have a number average molecular weight Mn in the range of 400 g / mol to 10.000 g / mol, preferably 500 g / mol to 5.000 g / mol, determined by gel permeation chromatography as described above. Preferred polyether components b) are polyethylene oxide polyols, polypropylene oxide polyols and polytetrahydrofuran polyols (poly-THF) having a molecular weight Mn of 400 g / mol to 10,000 g / mol, preferably 500 g / mol to 5,000 g / mol. In this case, particularly low molecular weight polyether polyols can be water-soluble in the case of a correspondingly high OH content.

[0045] Aliphatic polycarbonate polyols suitable as polyols b) are obtainable by reacting carbonic acid derivatives (e.g. diphenyl carbonate, dimethyl carbonate or phosgene) with diols. Useful diols of this type include, for example, ethylene glycol, 1,2- and 1,3-propylene glycol, 1,3- and 1,4-butanediol, 1,6-hexanediol, 1,8-octanediol, neopentyl glycol, 1,4-bishydroxymethylcyclohexane, 2-methylpropane-1,3-diol, 2,2,4-trimethylpentane-1,3-diol, dipropylene glycol, polypropylene glycol, dibutylene glycol, polybutylene glycol, and lactone-modified diols. The diol component preferably contains 40% to 100% by weight of 1,6-hexanediol and / or hexanediol derivatives, preferably those with ether or ester groups and terminal OH groups, such as the product obtained by reacting 1 mol of hexanediol with at least 1 mol, preferably 1 mol to 2 mol of ε-caprolactone, or by etherifying hexanediol with itself to obtain dihexanediol or trihexanediol. Polyether polycarbonate polyols can also be used. Among aliphatic polycarbonate polyols, polycarbonate polyols based on dimethyl carbonate and hexanediol and / or butanediol and / or ε-caprolactone are preferred. Polycarbonate polyols based on dimethyl carbonate and hexanediol and / or ε-caprolactone are very particularly preferred. Preferred polycarbonate polyols have a molecular weight Mn of 400 g / mol to 10.000 g / mol, preferably 500 g / mol to 5.000 g / mol, determined by gel permeation chromatography as described above.

[0046] The polyol composition provided in step (i) may contain one or more additional active hydrogen compounds c) different from compounds a) and b). Typically, the active hydrogen compound c) has a molecular weight of at most 400 g / mol. Suitable active hydrogen compounds c) may have 1, 2, 3 or 3, preferably 2 functional groups capable of reacting with isocyanate groups, the functional groups being selected in particular from OH, NH2 or SH. In particular, compound c) is a selected compound having a molecular weight of at most 400 g / mol and having 2 OH groups per molecule as the only functional groups.

[0047] Specifically, the active hydrogen compound c) is selected from: aliphatic diol compounds having 2 to 20 carbon atoms, such as ethylene glycol, 1,2-propylene glycol, 1,3-propylene glycol, 1,1-dimethylethane-1,2-diol, 2-butyl-2-ethyl-1,3-propylene glycol, 2-ethyl-1,3-propylene glycol, 2-methyl-1,3-propylene glycol, neopentyl glycol, hydroxypivalic acid neopentyl glycol ester, 1,2-butanediol, 1,3-butanediol and 1,4-butanediol, 1,6-hexanediol, 1,10-decanediol, 2-ethyl-1,3-hexanediol, 2,4-diethyloctan-1,3-diol; cyclic aliphatic diol compounds having 3 to 14 carbon atoms aliphatic amino alcohols having 2 to 20 carbon atoms, such as monoethanolamine, diethanolamine, monopropanolamine, dipropanolamine, N-methyldiethanolamine and N-methyldipropanolamine.

[0048] Particularly preferred are compounds c) selected from aliphatic diols having 2 to 12 carbon atoms, such as 1,4-butanediol, 1,5-pentanediol and neopentyl glycol.

[0049] Preferably, the amount of active hydrogen compound c) does not exceed 20% by weight, particularly 10% by weight, especially 5% by weight, based on the total weight of the liquid mixture. If present, the amount of active hydrogen compound c) is 0.1% to 20% by weight, particularly 0.2% to 10% by weight, especially 0.5% to 5% by weight, based on the total weight of the liquid mixture.

[0050] Preferably, the polyol composition provided in step (i) comprises less than 10 wt.-%, particularly at most 5 wt.-%, especially at most 1 wt.-% or 0 wt.-%, based on the total weight of the liquid mixture, of compounds having only one active hydrogen group per molecule.

[0051] Preferably, the liquid mixture of polyol compounds provided in step (i) contains less than 10% of organic compounds that do not have any active hydrogen functional groups and are therefore inert under the reaction conditions. These compounds generally have a molecular weight of up to 200 g / mol and are also referred to as "organic solvents". Examples of organic solvents include, but are not limited to, ketones having 3 to 8 carbon atoms, in particular aliphatic or alicyclic ketones having 3 to 8 carbon atoms, such as acetone, methyl ethyl ketone, cyclohexanone and isobutyl methyl ketone; and aliphatic or alicyclic ethers, for example tetrahydrofuran, dioxane or di-C1-C4-alkyl ethers of mono-, di- or tri-alkylene glycols, such as diethylene glycol dimethyl ether, triethylene glycol dimethyl ether, dipropylene glycol dimethyl ether, tripropylene glycol dimethyl ether ; esters, for example C4-C8 lactones, such as butyrolactone, valerolactone or caprolactone; aliphatic ether esters, for example C1-C4 alkoxy-C2-C4 alkyl acetates and propionates, such as methoxypropyl acetate; or carbonates, such as ethylene carbonate, dimethyl carbonate, diethyl carbonate; N-alkyl-2-pyrrolidone, such as N-methyl-2-pyrrolidone, N-ethyl-2-pyrrolidone or higher homologues; and mixtures thereof. Specifically, the liquid mixture of polyol compounds provided in step (i) does not contain any organic compound without any active hydrogen functional group, or contains less than 2% by weight of said compound, more preferably less than 1% by weight of said compound, in particular less than 0.5% by weight of said compound. According to the present invention, the preparation of the polymer can be solvent-free.

[0052] In particular, the polyol composition provided in step (i) consists of at least 90% by weight, in particular at least 95% by weight, especially at least 99% by weight, of compounds a) and b), based on the total weight of the liquid mixture.

[0053] The liquid mixture may contain additional additives, such as a catalyst that catalyzes the reactive components a), b) and optionally c) contained in the liquid mixture to form a polyurethane with an isocyanate compound. The amount of the catalyst is generally not more than 1% by weight, and is generally in the range of 0.1% to 1% by weight, based on the total weight of the liquid mixture. Suitable catalysts include, but are not limited to, tin compounds such as tin octoate, dibutyltin dilaurate, bismuth neodecanoate or bismuth dioctoate and tertiary amines such as dimethylbenzylamine, trimethylamine, 1,4-diazabicyclo[2.2.2]octane or any other catalyst known to those skilled in the art, which promotes the formation of carbamate groups by the reaction of the hydroxyl groups in compounds a) and b) with the isocyanate groups of the isocyanate compound d). Further catalysts are described, for example, in Houben-Weyl, Methoden der Organischen Chemie, Volume XIV / 2, Thieme-Verlag, Stuttgart 1963, page 60f, and in Ullmanns der Technischen Chemie, 4th edition, volume 19 (1981), page 306.

[0054] In step (i), a polyol composition is provided, wherein the compounds dissolve each other. In this article, the term "dissolve each other" means that the liquid mixture is substantially uniform and does not have visible inhomogeneity. In other words, the liquid mixture is visually transparent to the human eye. For this reason, step (i) generally includes mixing compounds a), b) and optionally c) and d), and heating the mixture obtained therefrom until the compounds dissolve each other. Mixing and heating can be performed simultaneously or continuously. Usually the heating temperature needs to reach at least 60°C, particularly at least 70°C, especially at least 90°C, for example, in the range of 60°C to 250°C, particularly in the range of 70°C to 160°C, particularly in the range of 90°C to 140°C, more preferably in the range of 100°C to 140°C. The time for achieving mutual dissolution of the components of the liquid mixture can vary and depends on the temperature. Those skilled in the art will easily find suitable conditions for achieving mutual dissolution of the components of the liquid mixture by conventional methods. The time for achieving mutual dissolution is generally in the range of 5 minutes to 180 minutes. Dissolution can be performed in a continuous manner or in a batch manner. For example, the dissolution is carried out in a continuously or batchwise operated stirred tank reactor which is heated to the temperature required for complete mutual dissolution of the components of the liquid mixture.

[0055] Generally speaking, the polyol composition provided in step (i) does not contain more than trace amounts of water to avoid undesirable side reactions of isocyanate groups in step (ii). Preferably, based on the gross weight of the polyol composition, the water content of the polyol composition provided in step (i) is less than 0.5 wt %, particularly less than 0.3 wt %, and may be as low as 0.1 wt % or even lower. The water content of the polyol composition can be measured, for example, by Karl Fischer titration, for example, according to the scheme of DIN ENISO 15512:2019.

[0056] According to step (ii), the polyol composition (PC) provided in step (i) is contacted with at least one isocyanate composition (IC) comprising at least one isocyanate (I1) having on average at least 1.5 isocyanate groups.

[0057] For the purposes of the present invention, in step ii), in principle any isocyanate having an average of at least 1.5 isocyanate (NCO) groups can be used. In the context of the present invention, isocyanates are also referred to as "polyisocyanates". That is, the at least one isocyanate comprises a plurality of NCO functional groups, for example 2, 3 or 4 NCO functional groups, or any value or value range therein. It should be understood that the at least one polyisocyanate includes both monomeric diisocyanates, i.e. compounds having 2 NCO functional isocyanates, and oligomeric forms thereof having an average of more than 2 NCO functional groups, for example 2 to 4 NCO functional groups.

[0058] The at least one polyisocyanate generally has an NCO content in the range of 10% to 50% by weight, preferably in the range of 15% to 45% by weight. The determination of the NCO content in weight percent is accomplished by standard chemical titration analysis known to those skilled in the art, and therefore, the present invention is not limited by any such method.

[0059] For the purposes of the present invention, the at least one polyisocyanate is preferably selected from the group consisting of aliphatic diisocyanates, cycloaliphatic diisocyanates and aromatic diisocyanates.

[0060] According to another embodiment, the present invention also relates to a process as disclosed above, wherein the isocyanate (I1) is selected from the group consisting of aliphatic diisocyanates, cycloaliphatic diisocyanates and aromatic diisocyanates or aromatic / aliphatic oligomeric or polymeric isocyanates.

[0061] The term "aliphatic diisocyanate" refers to a molecule having two isocyanate groups attached to an acyclic saturated hydrocarbon group typically containing 4 to 18 carbon atoms. Examples of aliphatic diisocyanates include, but are not limited to, tetramethylene-1,4-diisocyanate, pentamethylene-1,5-diisocyanate, hexamethylene-1,6-diisocyanate, decamethylene diisocyanate, 1,12-dodecane diisocyanate, 2,2,4-trimethyl-hexamethylene diisocyanate, 2,4,4-trimethyl-hexamethylene diisocyanate, 2-methyl-1,5-pentamethylene diisocyanate, and the like, and mixtures thereof. Preferred aliphatic diisocyanates are pentamethylene-1,5-diisocyanate, hexamethylene-1,6-diisocyanate, 2,2,4-trimethyl-hexamethylene-1,6-diisocyanate and 2,4,4-trimethyl-hexamethylene-1,6-diisocyanate and mixtures thereof.

[0062] The term "alicyclic diisocyanate" refers to a molecule having two isocyanate groups attached to a saturated hydrocarbon group with at least one cyclic moiety. Alicyclic diisocyanates generally contain 6 to 18 carbon atoms. Examples of alicyclic diisocyanates d2) include, but are not limited to, cyclobutane-1,3-diisocyanate, 1,2-, 1,3- and 1,4-cyclohexane diisocyanate, 2,4- and 2,6-diisocyanato-1-methylcyclohexane (=2,4- and 2,6-hexahydrotoluene diisocyanate), 4,4'- and 2,4'-dicyclohexyl diisocyanate, isocyanatomethylcyclohexane isocyanate, isocyanatoethylcyclohexane isocyanate, bis(isocyanatomethyl)cyclohexane, 4,4'-diisocyanatodicyclohexylmethane (12-MDI), isophorone diisocyanate and mixtures thereof. Preferred cycloaliphatic diisocyanates d2) are 1,2-, 1,3- and 1,4-cyclohexane diisocyanate, 2,4- and 2,6-diisocyanato-1-methylcyclohexane, 4,4'- and 2,4'-dicyclohexyl diisocyanate, bis(isocyanatomethyl)cyclohexane, 4,4'-diisocyanatodicyclohexylmethane (12-MDI), isophorone diisocyanate and mixtures thereof. Isophorone diisocyanate is usually a mixture, in particular a mixture of cis and trans isomers, usually in a mass ratio of 60:40 to 80:20, more particularly 70:30 to 75:25, very particularly about 75:25.

[0063] The term "aromatic diisocyanate" refers to a molecule having two isocyanate groups attached directly and / or indirectly to an aromatic ring. Aromatic diisocyanates typically have 8 to 18 carbon atoms. Examples of aromatic diisocyanates include, but are not limited to, 1,2-, 1,3- and 1,4-phenylene diisocyanate, naphthylene-1,5-diisocyanate, 2,4- and 2,6-toluene diisocyanate, 2,4'-, 4,4'- and 2,2'-diphenyl diisocyanate, 2,2'-, 2,4'- and 4,4'-diphenylmethane diisocyanate, 1,2-, 1,3- and 1,4-phenylenediisocyanate and meta-tetramethylphenylenediisocyanate (TMXDI) and mixtures thereof. Preferred aromatic diisocyanates d2) are 2,4- and 2,6-toluene diisocyanate, 2,4′-, 4,4′- and 2,2′-diphenyl diisocyanate, 2,2′-, 2,4′- and 4,4′-diphenylmethane diisocyanate, 1,2-, 1,3- and 1,4-phenylenediisocyanate and meta-tetramethylxylylene diisocyanate (TMXDI) and mixtures thereof.

[0064] Preferably, the isocyanate composition comprises at least one of an alicyclic diisocyanate compound and an aromatic diisocyanate. Specifically, the isocyanate is selected from alicyclic diisocyanate compounds, aromatic diisocyanate compounds, and mixtures thereof with aliphatic diisocyanate compounds. More preferably, the isocyanate composition comprises at least one of an alicyclic diisocyanate compound and an aromatic diisocyanate compound, the alicyclic diisocyanate compound being selected from 1,2-, 1,3- and 1,4-cyclohexane diisocyanate, 2,4- and 2,6-diisocyanato-1-methylcyclohexane, 4,4'- and 2,4'-dicyclohexyl diisocyanate, bis(isocyanatomethyl)cyclohexane, 4,4'-diisocyanato-1-methylcyclohexane, 4,4'-diisocyanato-2 ... diisocyanato-1-methylcyclohexane, 4,4'- and 2,4'-dicyclohexyl diisocyanate, bis(isocyanatomethyl)cyclohexane, 4,4'-diisocyanato-1-methylcyclohexane, isophorone diisocyanate and mixtures thereof, in particular selected from the group consisting of 2,4- and 2,6-di ... The aromatic diisocyanate is selected from bis(4-isocyanatocyclohexyl)methane, isophorone diisocyanate and mixtures thereof; the aromatic diisocyanate is selected from 2,4- and 2,6-toluene diisocyanate, 2,4'-, 4,4'- and 2,2'-diphenyl diisocyanate, 2,2'-, 2,4'- and 4,4'-diphenylmethane diisocyanate, 1,2-, 1,3- and 1,4-phenylenediisocyanate and meta-tetramethylphenylenediisocyanate Isocyanates (TMXDI) and mixtures thereof, in particular selected from 2,4- and 2,6-toluene diisocyanate, 2,2'-, 2,4'- and 4,4'-diphenylmethane diisocyanate, 1,2-, 1,3- and 1,4-phenylenediisocyanate and mixtures thereof, in particular selected from 2,4- and 2,6-toluene diisocyanate, 4,4'-diisocyanatodiphenylmethane and mixtures thereof.

[0065] Preferably, the total amount of diisocyanates is at least 60% by weight, in particular at least 70% by weight or 100% by weight, based on the total weight of isocyanate compounds d) fed to the reactor.

[0066] In particular, the isocyanate compound is selected from toluene diisocyanate, 4,4'-diisocyanato diphenylmethane, bis(4-isocyanato cyclohexyl) methane, isophorone diisocyanate, mixtures thereof and mixtures thereof with hexamethylene diisocyanate. Preferably, the total amount of toluene diisocyanate, 4,4'-diisocyanato diphenylmethane, bis(4-isocyanato cyclohexyl) methane and isophorone diisocyanate is at least 60% by weight, in particular at least 70% by weight or 100% by weight, based on the total weight of the isocyanate compound d) fed to the reactor. In the isocyanate compound d), a small portion of the diisocyanate may be replaced by an isocyanate compound having more than 2 isocyanate groups per molecule. Preferably, the amount of such isocyanate compounds does not exceed 10% of the total amount of the isocyanate composition.

[0067] The relative amount of the isocyanate composition is preferably selected so that the molar ratio of NCO groups to isocyanate-reactive groups (i.e., active hydrogen groups) present in the polyol composition provided in step (i) can be varied depending on the NCO content of the polyurethane to be prepared. Typically, the NCO group content of the resulting product is in the range of 0.1 wt. % to 35 wt. %.

[0068] The polyol composition (PC) provided in step (i) is contacted with at least one isocyanate under suitable conditions to prepare polyurethane. For example, the components can be fed to the reactor. The feeding can be carried out via a separate feed line, or as a preformed mixture of a liquid mixture of the polyol composition provided in step (i) and at least one isocyanate. Preferably, the liquid mixture provided in step (i) is mixed with at least one isocyanate, and the mixture is subsequently fed to the reactor. During mixing, a dynamic mixing element or a static mixing element can be used, preferably the latter.

[0069] Mixing may also be performed at elevated temperature, for example at a temperature of at least 50°C, in particular at a temperature in the range of 50°C to 150°C.

[0070] The reaction conditions for polyurethane formation will depend on the reactivity of the components present in the polyol composition (PC) provided in step (i), the reactivity of the isocyanate and the presence or absence of a catalyst. Typically, the reaction temperature is in the range of 50° C. to 150° C., particularly in the range of 60 to 130° C. The residence time in the reactor is typically in the range of 15 minutes to 240 minutes, particularly in the range of 30 minutes to 120 minutes. A person skilled in the art will find suitable reaction conditions by performing routine experiments.

[0071] Preferably, step (ii) is at least initially carried out in the absence of an organic solvent having no hydrogen-active groups. Thus, the amount of organic solvent (i.e., an organic compound having no active hydrogen functional groups and a molecular weight of at most 200 g / mol) in the reactants fed to the reactor is preferably less than 1 wt%, in particular less than 0.1 wt% or 0, based on the total weight of the reactants fed to the reactor.

[0072] Depending on the molar ratio of NCO groups to isocyanate-reactive groups in the compounds fed to the reactor, the resulting polyurethane may still have reactive NCO groups at its ends. The content of NCO groups in the polyurethane may vary and is generally in the range of 0.1% to 35% by weight. Preferably, the NCO group content of the resulting product is in the range of 1% to 25% by weight, in particular in the range of 1.5% to 20% by weight, more preferably in the range of 3% to 15% by weight, particularly preferably in the range of 4% to 15% by weight.

[0073] According to another aspect, the present invention also relates to a polyurethane having carboxyl groups or derivatives thereof obtained or obtainable according to the process for preparing polyurethane disclosed above.

[0074] The carboxyl groups of the polyurethane are mainly derived from the polymerized compound a). In other words, the polymerized repeating unit compound a) forms the majority of the carboxyl groups in the polyurethane. Specifically, at least 90% or all of the carboxyl groups of the polyurethane are derived from the polymerized compound a). The remaining carboxyl groups may be derived from other components, such as the polyol compound b) or from partial degradation.

[0075] According to another embodiment, the present invention also relates to a polyurethane as disclosed above, wherein the polyurethane has a carboxyl number in the range of 0.2 mg KOH / g to 50 mg KOH / g according to ISO 2114:2000, wherein 70 mL acetone is used as solvent and potassium hydrogen phthalate is used as titrant.

[0076] According to another embodiment, the present invention also relates to a polyurethane as disclosed above, wherein the polyurethane has an NCO content in the range of 0.1% to 35%. Preferably, the NCO group content of the polyurethane is in the range of 1% to 25% by weight, in particular in the range of 1.5% to 20% by weight, more preferably in the range of 3% to 15% by weight, particularly preferably in the range of 4% to 15% by weight.

[0077] The polyurethanes obtained according to the invention can be used as binders or adhesives or can also be reacted with further polyol components to form higher molecular weight polyurethanes.

[0078] According to a further aspect, the present invention therefore also relates to the use of a polyurethane obtainable according to the process disclosed above as an adhesive, as a binder or as a component for the preparation of polyurethanes.

[0079] Polyurethane can be used for different applications. For example, polyurethane can be applied to a surface and used as an adhesive. In addition, polyurethane can be mixed with particles such as small rubber particles or pellets or foamed particles and can react as a binder to form a shaped article from the particles. Suitable applications can also be flooring applications or wall panels.

[0080] According to another embodiment, the present invention also relates to the use as disclosed above, wherein the polyurethane is used as an adhesive for the preparation of consumer goods, industrial goods, building goods, sports equipment, automotive interiors or flooring.

[0081] According to another embodiment, the present invention also relates to the use as disclosed above, wherein the polyurethane is used as binder for binding the particles.

[0082] According to a further aspect, the invention also relates to a method for producing a composite material, wherein the polyurethane obtained by the method according to the invention is used as an adhesive, as a binder or as a component for producing a polyurethane.

[0083] It has been found that the polyurethanes according to the invention are good adhesives and can be used as binders or adhesives in processes for preparing composite materials starting from two or more components.

[0084] Therefore, according to another aspect, the present invention also relates to a method for preparing a composite material comprising at least a first component (C1) and a second component (C2), the method comprising the following steps:

[0085] (x) providing a first component (C1) and a second component (C2),

[0086] (y) providing a polyurethane obtained or obtainable according to the process disclosed above or a polyurethane according to the invention,

[0087] (z) bonding the first component and the second component by means of the polyurethane provided in step (y).

[0088] According to step (x), a first and a second component are provided. According to the invention, three or more components can also be combined. These components can consist of the same material or different materials and can have the same or different sizes.

[0089] For example, suitable components (C1) and / or (C2) are natural and biomaterials such as wood, cork, sawdust, natural fibers, leather, metal and stone, sand, synthetic materials, polymer-based materials, thermoplastics, thermoplastic elastomeric materials, elastomers, duromers, extruded articles, injection molded articles, pressed articles, foamed articles, particle foams, cable sheaths, hoses, molded elements, drive belts, fiber materials, nonwovens, films, molded parts, soles, sporting goods, footwear articles, plugs, housings or damping elements for the electrical industry, the automotive industry, machine construction, 3D printing, medicine or consumer products. Preferred bonded articles are consumer and industrial products or articles for construction and transportation, such as footwear articles, parts of footwear articles, car interiors, car seats and dashboards, car roof linings, dashboards, car batteries, solar panels, wind turbine blades, decorations, furniture, insulation, disposable articles, packaging, food packaging (such as meat, vegetable or cheese packaging), etc. More preferred are footwear articles or parts of footwear articles.

[0090] The first component may be made of a thermoplastic polymer. The thermoplastic polymer is preferably a thermoplastic elastomer, more preferably an expanded thermoplastic elastomer. Thermoplastic polymers are plastic polymer materials that become pliable or moldable at certain elevated temperatures and solidify upon cooling. Examples of thermoplastic polymers are thermoplastic polyethylene, thermoplastic polypropylene, thermoplastic polyvinyl chloride, thermoplastic polystyrene, thermoplastic polyamide, thermoplastic polyester and thermoplastic polyurethane. Thermoplastic elastomers are preferably composed of phase-separated block copolymers and combine the performance benefits of rubber such as flexibility and elasticity with the ease of processing of thermoplastic polymers.

[0091] Suitable materials for the first component are thermoplastic elastomers, for example selected from the group consisting of thermoplastic elastomers such as thermoplastic olefins, thermoplastic polyamides, thermoplastic polyurethanes (TPU), thermoplastic copolyamides (e.g. thermoplastic copolyether polyamides), thermoplastic copolyester elastomers (e.g. copolyetheresters or copolyesteresters), styrene block copolymers (e.g. styrene butadiene block copolymers), thermoplastic ethylene vinyl acetate and mixtures or blends thereof.

[0092] When thermoplastic polyurethanes are used, the thermoplastic polyurethanes may be any desired thermoplastic polyurethanes known to the person skilled in the art. Thermoplastic polyurethanes and methods for their preparation have been extensively described, for example in Gerhard W. Becker and Dietrich Braun, Kunststoffhandbuch, Volume 7, Polyurethane, Carl Hanser Verlag, Munich, Vienna, 1993. Thermoplastic polyurethanes are preferably prepared by reacting a mixture of isocyanates with isocyanate-reactive compounds (preferably with a molecular weight of 0.5 kg / mol to 10 kg / mol) and optionally chain extenders (preferably with a molecular weight of 0.05 kg / mol to 0.5 kg / mol). Thermoplastic polyurethanes are preferably prepared by further adding to the mixture at least one chain transfer agent, a catalyst and optionally at least one filler, auxiliary agent or additive.

[0093] According to another embodiment, the present invention also relates to a process as disclosed above, wherein the first component (C1 ) comprises a thermoplastic polymer.

[0094] According to another embodiment, the present invention also relates to a process as disclosed above, wherein the first component (C1 ) comprises a foamed thermoplastic polymer.

[0095] Expanded polymers (also called foamed materials or foams), in particular expanded polymer particles (also called particle foams) are known and have been extensively described in the literature, for example in Ullmann's "Enzyklop***die der technischen Chemie", 4th edition, volume 20, page 416 et seq. The most preferred material for the first component is expanded thermoplastic polyurethane (E-TPU). Suitable E-TPUs and methods for their preparation are described, for example, in WO 2007 / 082838, WO 2013 / 153190 or WO 2015 / 052265.

[0096] Suitable materials for the second or any further component are, for example, those materials common in the footwear industry and may be, for example, selected from the group of materials mentioned for the first component, or from the group consisting of crepe rubber, natural leather, synthetic leather, polyurethane (e.g. polyurethane foam and / or thermoplastic polyurethane TPU), thermoplastic rubber, styrene-butadiene rubber, polyvinyl acetate, polyamide (PA), polyvinyl chloride, polystyrene, acrylonitrile butadiene styrene, polyethylene terephthalate (PET), polybutylene terephthalate, textiles, fabrics, thermoplastic polyurethane knitted fibers and combinations thereof. Preferred are uppers made of PET, TPU or PA. Most preferred are uppers made of PET.

[0097] According to another embodiment, the present invention also relates to a process as disclosed above, wherein the second component (C2) comprises a thermoplastic polymer.

[0098] Preferred bonded articles are articles wherein the first component is an expanded thermoplastic polyurethane and the second component is a material selected from the group consisting of crepe rubber, natural leather, synthetic leather, polyurethane (such as foam or dense material) or cross-linked polyurethane (e.g., thermoplastic polyurethane), thermoplastic rubber, styrene-butadiene rubber, vinyl acetate, polyamide, polyvinyl chloride, polystyrene, acrylonitrile butadiene styrene, polyethylene terephthalate, textiles, fabrics, and combinations thereof.

[0099] One aspect of the present invention is a recyclable footwear article or part thereof, comprising a first component, a second component and a polyurethane adhesive of the present invention that bonds the first component to the second component, wherein at least one of the components is made of thermoplastic polyurethane, preferably made of expanded thermoplastic polyurethane; and the first component and the second component can be debonded by the following debonding procedure 1): treated with an aqueous surfactant composition at a temperature of 60°C to 130°C, preferably 60°C to 100°C or 70°C to 100°C; and the pH is 4 to 14, preferably 6 to 14, especially 10 to 14, most preferably 11 to 14. This debonding step can also be assisted / accelerated by using an ultrasonic bath. The first component and the second component can also be debonded by the following debonding procedure 2): exposing the article to microwaves in a water bath for a period of 1 second to 15 minutes, preferably 15 seconds to 10 minutes. The first component, the second component or both can be any component commonly found in footwear articles, and preferably include components selected from the group consisting of an upper, an insole, an outsole, a midsole, and a combination thereof. For example, the polyurethane adhesive may bond an upper and an outsole, an upper and an insole, a midsole and an outsole, or any other combination of components common in the footwear industry.

[0100] Preferably, the first component is a sole made of thermoplastic polyurethane; and the second component is an upper, preferably made of polyethylene terephthalate, polyamide such as PA6 or cotton. The first component sole preferably contains a midsole made of expanded thermoplastic polyurethane. The adhesive bonds the upper to the sole and / or midsole. In some aspects, the adhesive bonds two sole components, such as the outsole and the midsole. In some aspects, the adhesive bonds the sole or the sole component to the upper (or the component of the upper). In some aspects, the upper component is the vamp or the back. For example, the polyurethane adhesive described herein can be used to bond the upper surface of the outsole to the lower surface of the midsole. This will allow the outsole and the midsole to be debonded more easily. The adhesive described herein can be used to bond the upper surface of the midsole to the lower surface of the upper. This will allow the sole to be debonded more easily from the upper.

[0101] For example, a shoe may be formed by a sole and an upper, and the sole includes an outer sole and a midsole. Each of these components may be bonded using a debondable adhesive as described herein. Using a debondable adhesive as described herein allows for easy debonding, such as the materials of the upper, outer sole, and / or midsole to be recycled separately.

[0102] According to the invention, for example, the woven component and one or more further components (for example foamed beads) can be combined in one step using the polyurethane according to the invention as a binder and / or adhesive.

[0103] According to the present invention, for example, one component consisting essentially of a polymer foam may be combined with a second component that is essentially a woven structure.

[0104] It is also possible to combine several particulate components, such as foamed beads having a size, for example, in the range of 1 mm to 20 mm, by using the polyurethane according to the invention as a binder which substantially covers the particulate components. Furthermore, specific components such as rubber crumbs or other small chopped materials, such as cork and wood chips, can be used. Suitable particulate components can be obtained, for example, by shredding rubber or polymer materials, such as shoes.

[0105] The application of the polyurethane adhesive is preferably carried out by brushing, spraying, knife coating, printing or roller coating, followed by a drying step. The adhesive can be applied, for example, using an automated or machine-assisted method, such as using an automatic sprayer. The adhesive is applied to one or preferably two substrates.

[0106] The method of bonding the first component to the second component may include various surface treatments of the first component, the second component, or both, typically applied using an adhesive. The bonding method may include treating one or both of the surfaces of the first component and the second component prior to applying the polyurethane adhesive.

[0107] The method of bonding the first component to the second component may include applying pressure to ensure the appropriate bonding level between the components. For example, the bonding method may include applying pressure to the first component and the second component for a period of time to bond the first component and the second component. The pressure may be, for example, about 2000 kPa to about 5500 kPa, and the time period may be about 10 minutes to about 30 minutes, but is not limited thereto. The bonding method may also include applying heat to bond the first component and the second component.

[0108] The bonded article includes at least two components bonded to each other. The bonded article can be formed using a polyurethane adhesive by coating one or both components with the adhesive and contacting the components to each other.

[0109] The bond strength is preferably about 5 N / 50 mm to material breakage, more preferably about 10 N / 50 mm to about 200 N / 50 mm, and most preferably about 20 N / 50 mm to about 150 N / 50 mm. The bond strength is measured according to ISO 20344:2011, 5, 2. In some cases, during the peel test, the bonded material may suffer material damage. In these cases, the measured values ​​according to ISO 20344:2011, 5, 2 may also be far below 5 N / 50 mm due to failure of the substrate material, but have nothing to do with adhesion.

[0110] According to another aspect, the present invention also relates to an article obtained or obtainable by a process as disclosed above.

[0111] The articles according to the present invention can be used in a variety of applications such as shoes, furniture, seats, automotive interiors, automotive exteriors, medical devices, industrial applications, consumer products such as consumer electronics, wearable devices, headphones, speakers, packaging, protective equipment, as cushioning pads, toys, animal toys, saddles, balls and sports equipment, such as sports mats, sports gloves, or as floor coverings and wall panels.

[0112] The article may also be footwear or a part of footwear, preferably selected from the group consisting of shoes, boots and sandals. Suitable shoes are, for example, sports shoes, tennis shoes, cross-training shoes, football shoes, children's shoes, dress shoes and casual shoes.

[0113] It has been found that the articles according to the invention can be disassembled using suitable mild conditions, which makes them easier to recycle. According to the invention, the articles can be disassembled and the individual components can be obtained, thereby allowing the components to be separated and recycled. In this way, the mixing of different components can be reduced or avoided. In addition, the individual components obtained can also be reused.

[0114] According to another embodiment, the present invention therefore also relates to an article as disclosed above, wherein the article can be disassembled into components C1 and / or C2.

[0115] According to another embodiment, the present invention also relates to an article as disclosed above, wherein the article is recyclable. If the components can be recovered in a recycling process, the components can be reused as such. Furthermore, the components can also be recycled in a process comprising a further extrusion step of the thermoplastic elastomer.

[0116] According to the invention, the article can be prepared, for example, by bonding the individual components (at least components C1 and C2) to obtain the article. The article can then be disassembled and components C1 and / or C2 can be recovered. Components C1 and / or C2 can then be reused after a suitable separation step to prepare an article as described above.

[0117] According to another embodiment, the present invention also relates to a preparation as disclosed above, wherein recycling of the preparation produces components (C1 ) and / or (C2).

[0118] The article according to the present invention may be suitable for different applications, such as consumer products. According to another embodiment, the present invention also relates to an article as disclosed above, wherein the article is a consumer product or a part of a consumer product.

[0119] It has been found that the article can be debonded using mild conditions. Debonding can be performed by treating the article with a solution having a pH of 8 to 14 at a temperature in the range of 40°C to 150°C, or by exposing the article to microwaves in a water bath for a period of 1 second to 15 minutes, preferably 15 seconds to 10 minutes.

[0120] At least two components of the bonded article can be debonded by treatment with an aqueous surfactant composition at a temperature of 40°C to 150°C, preferably 60°C to 130°C, more preferably 60°C to 100°C or 70°C to 100°C and a pH of 8 to 14, preferably 9 to 14. If necessary, the bonded article is cut into smaller pieces before debonding. Debonding is carried out after the bonded article (or its pieces) are treated with an aqueous surfactant solution having a pH of 8 to 14 and a temperature of 50°C to 150°C for preferably 2 to 120 minutes. A preferred debonding method is treatment with an aqueous surfactant composition, characterized in that the pieces of the bonded article are immersed in an aqueous surfactant solution having a pH of 8 to 14 and a temperature of 50°C to 150°C for up to 60 minutes, while stirring or shaking or ultrasonic treatment. Suitable equipment may, for example, include mixing and heating devices, or may also be a device that allows continuous shaking, such as a tumble machine or a washing machine.

[0121] Alternatively, the article may be debonded by exposing the entire article or a portion thereof (which may be cut prior to treatment in a water bath, for example) to microwaves for a period of, for example, 1 second to 15 minutes, preferably 15 seconds to 10 minutes. The microwave radiation may, for example, have a frequency of 2 GHz to 3 GHz and / or a power level of 500 W to 1500 W. Suitable temperatures for treatment and the water bath may, for example, be in the range of 20° C. to 35° C.

[0122] According to another aspect, the invention also relates to a method for disassembling an article obtained or obtainable by the method according to the invention, comprising steps (A) and (B), which steps are also referred to as debonding procedure 1):

[0123] (A) treating the article with a solution having a pH in the range of 8 to 13 at a temperature in the range of 50°C to 150°C;

[0124] (B) recovering components (C1) and / or (C2);

[0125] Or comprising steps (A') and (B'), which are also referred to as debonding procedure 2):

[0126] (A') Expose the product placed in a water bath to microwaves

[0127] (B') Recovering components (C1) and / or (C2).

[0128] A preferred debonding method comprises treating the bonded article or portion thereof with an aqueous composition at a temperature of 60 to 100°C and a pH of 8 to 14 for 2 to 360 minutes, preferably at a temperature of 80 to 100°C and a pH of 8 to 14 for 30 to 180 minutes.

[0129] According to an alternative embodiment, debonding can also be accomplished by treatment with microwaves. The article can be placed, for example, in water and then exposed to microwave radiation. Therefore, according to another embodiment, the present invention also relates to a method for disassembling an article obtained or obtainable by the method according to the present invention, the method comprising the following steps:

[0130] (A') exposing the article placed in a water bath to microwaves;

[0131] (B') Recovering components (C1) and / or (C2).

[0132] Preferably, there is no residual adhesive on the surface of the debonded component. This has the advantage that residual adhesive does not interfere with the recycling of the debonded component. According to the invention, it is also possible for a layer of residual adhesive to remain on the debonded component, which can be used in further processes without a recycling step.

[0133] Preferably, the bonded article resists debonding at temperatures up to 60°C (without treatment with water, aqueous surfactant compositions or any other cleaning composition), and resists debonding when treated with aqueous surfactant compositions at temperatures up to 40°C.

[0134] Further embodiments of the invention can be found in the claims and the examples. It is to be understood that the features of the subject matter / method / use according to the invention described above and explained below can be used not only in the combination specified in each case, but also in other combinations without departing from the scope of the invention. For example, the combination of preferred features with particularly preferred features or the combination of features not further characterized with particularly preferred features etc. is therefore also implicitly covered, even if this combination is not explicitly mentioned.

[0135] Exemplary embodiments of the invention are listed below, but these do not limit the invention. In particular, the invention also encompasses those embodiments resulting from the dependent references and combinations specified below accordingly.

[0136] 1. A method for producing a polyurethane having a carboxyl group, the method comprising

[0137] (i) providing a polyol composition (PC), the polyol composition consisting essentially of the following components:

[0138] a) at least one compound (a) which carries at least one carboxyl group or a derivative thereof and at least one functional group comprising an active hydrogen which is reactive toward isocyanate groups;

[0139] b) at least one polyol compound (b) having an average of 1.5 to 3.5 hydroxyl groups per molecule;

[0140] c) optionally one or more additional active hydrogen compounds (c) different from compounds (a) and (b);

[0141] d) optionally one or more further additives not containing active hydrogen;

[0142] (ii) contacting the polyol composition (PC) provided in step (i) with at least one isocyanate composition (IC), the at least one isocyanate composition comprising at least one isocyanate (I1) having an average of at least 1.5 isocyanate groups, wherein the NCO group content of the obtained product is in the range of 0.1% to 35% by weight.

[0143] 2. A method according to embodiment 1, wherein the NCO group content of the obtained product is in the range of 0.5 wt. % to 30 wt. %, preferably the NCO group content of the obtained product is in the range of 1 wt. % to 25 wt. %, in particular in the range of 1.5 wt. % to 20 wt. %, more preferably in the range of 3 wt. % to 15 wt. %, particularly preferably in the range of 4 wt. % to 15 wt. %.

[0144] 3. The method according to embodiment 1 or 2, wherein the component (a) is selected from the group consisting of compounds having one carboxyl group and one or two functional groups, wherein the one or two functional groups are selected from the group consisting of SH, NH and OH groups.

[0145] 4. The method according to any one of embodiments 1 to 3, wherein the component (a) is selected from the group consisting of compounds having one carboxyl group and two OH groups.

[0146] 5. The method according to any one of embodiments 1 to 4, wherein the content of component (a) in the polyol composition is in the range of 3% to 50%.

[0147] 6. The method according to any one of embodiments 1 to 5, wherein the polyol (b) is selected from the group consisting of polyester polyols and polyether polyols.

[0148] 7. The method according to any one of embodiments 1 to 6, wherein the polyol (b) has an average molecular weight of less than 10000 g / mol.

[0149] 8. The process according to any one of embodiments 1 to 7, wherein the isocyanate (I1) is selected from the group consisting of aliphatic diisocyanates, cycloaliphatic diisocyanates and aromatic diisocyanates or aromatic / aliphatic oligomeric or polymeric isocyanates.

[0150] 9. A polyurethane having a carboxyl group or a derivative thereof obtained or obtainable according to the process according to any one of embodiments 1 to 8.

[0151] 10. The polyurethane according to embodiment 9, wherein the polyurethane has a carboxyl number in the range of 0.2 mg KOH / g to 50 mg KOH / g according to ISO 2114:2000, wherein 70 mL acetone is used as solvent and potassium hydrogen phthalate is used as titrant.

[0152] 11. The polyurethane according to any one of embodiments 9 to 10, wherein the NCO content of the polyurethane is in the range of 0.5% to 30%, preferably the NCO group content is in the range of 1% to 25% by weight, in particular in the range of 1.5% to 20% by weight, more preferably in the range of 3% to 15% by weight, particularly preferably in the range of 4% to 15% by weight.

[0153] 12. Use of a polyurethane obtained according to a process according to any one of embodiments 1 to 6 or a polyurethane according to any one of embodiments 9 to 11 as an adhesive, as a binder or as a component for preparing polyurethanes.

[0154] 13. The use according to embodiment 12, wherein the polyurethane is used as an adhesive for the preparation of consumer goods, industrial goods, building goods, automotive interiors and automotive batteries, sports equipment or flooring.

[0155] 14. The use according to embodiment 12, wherein the polyurethane is used as a binder for binding particles.

[0156] 15. A method for producing a composite material, wherein the polyurethane obtained according to any of the methods according to embodiments 1 to 8 or the polyurethane according to any of embodiments 9 to 12 is used as an adhesive, as a binder or as a component for producing a polyurethane, thus as an isocyanate-containing component of a two-component PU formulation.

[0157] 16. A method for preparing a composite material comprising at least a first component (C1) and a second component (C2), the method comprising the following steps:

[0158] (x) providing a first component (C1) and a second component (C2),

[0159] (y) providing a polyurethane obtained or obtainable according to a process according to any one of embodiments 1 to 6 or a polyurethane according to any one of embodiments 7 to 10,

[0160] (z) bonding the first component and the second component by means of the polyurethane provided in step (y).

[0161] 17. The method according to embodiment 16, wherein the first component (C1) comprises a thermoplastic polymer.

[0162] 18. The method according to embodiment 16 or 17, wherein the first component (C1) comprises a foamed thermoplastic polymer.

[0163] 19. The method according to any one of embodiments 16 to 18, wherein the second component (C2) comprises a thermoplastic polymer.

[0164] 20. An article obtained or obtainable by a method according to any one of embodiments 16 to 19.

[0165] 21. The article according to embodiment 20, wherein the article can be disassembled into components (C1) and / or (C2).

[0166] 22. The article of embodiment 20 or 21, wherein the article is recyclable.

[0167] 23. The article according to any one of embodiments 20 to 22, wherein recycling of the article produces components (C1) and / or (C2).

[0168] 24. The article of any one of embodiments 20 to 23, wherein the article is a consumer product or a part of a consumer product.

[0169] 25. A method for disassembling an article obtained or obtainable by the method according to any one of embodiments 16 to 19, said method comprising steps (A) and (B), which steps are also referred to as debonding procedure 1):

[0170] (A) treating the article with a solution having a pH in the range of 8 to 14 at a temperature in the range of 50°C to 150°C;

[0171] (B) recovering components (C1) and / or (C2);

[0172] Or comprising steps (A') and (B'), which are also referred to as debonding procedure 2):

[0173] (A') exposing the article placed in a water bath to microwaves,

[0174] (B') Recovering components (C1) and / or (C2).

[0175] 26. A method for producing a polyurethane having a carboxyl group, the method comprising

[0176] (i) providing a polyol composition (PC), the polyol composition consisting essentially of the following components:

[0177] a) at least one compound (a) which carries at least one carboxyl group or a derivative thereof and at least one functional group comprising an active hydrogen which is reactive toward isocyanate groups;

[0178] b) at least one polyol compound (b) having an average of 1.5 to 3.5 hydroxyl groups per molecule;

[0179] c) optionally one or more additional active hydrogen compounds (c) different from compounds (a) and (b);

[0180] d) optionally one or more further additives not containing active hydrogen;

[0181] (ii) contacting the polyol composition (PC) provided in step (i) with at least one isocyanate composition (IC), the at least one isocyanate composition comprising at least one isocyanate (I1) having an average of at least 1.5 isocyanate groups,

[0182] wherein the NCO group content of the obtained product is in the range of 0.1 wt % to 35 wt %. 27. A method for producing a polyurethane having a carboxyl group, the method comprising

[0183] (i) providing a polyol composition (PC), the polyol composition consisting essentially of the following components:

[0184] a) at least one compound (a) which carries at least one carboxyl group or a derivative thereof and at least one functional group comprising an active hydrogen which is reactive toward isocyanate groups;

[0185] b) at least one polyol compound (b) having an average of 1.5 to 3.5 hydroxyl groups per molecule;

[0186] c) optionally one or more additional active hydrogen compounds (c) different from compounds (a) and (b);

[0187] d) optionally one or more further additives not containing active hydrogen;

[0188] (ii) contacting the polyol composition (PC) provided in step (i) with at least one isocyanate composition (IC), the at least one isocyanate composition comprising at least one isocyanate (I1) having an average of at least 1.5 isocyanate groups,

[0189] wherein the NCO group content of the obtained product is in the range of 0.5% to 30% by weight,

[0190] Wherein component (a) is selected from the group consisting of compounds having one carboxyl group and two OH groups.

[0191] 28. A method for producing a polyurethane having a carboxyl group, the method comprising

[0192] (i) providing a polyol composition (PC), the polyol composition consisting essentially of the following components:

[0193] a) at least one compound (a) which carries at least one carboxyl group or a derivative thereof and at least one functional group comprising an active hydrogen which is reactive toward isocyanate groups;

[0194] b) at least one polyol compound (b) having an average of 1.5 to 3.5 hydroxyl groups per molecule;

[0195] c) optionally one or more additional active hydrogen compounds (c) different from compounds (a) and (b);

[0196] d) optionally one or more further additives not containing active hydrogen;

[0197] (ii) contacting the polyol composition (PC) provided in step (i) with at least one isocyanate composition (IC), the at least one isocyanate composition comprising at least one isocyanate (I1) having an average of at least 1.5 isocyanate groups,

[0198] wherein the NCO group content of the obtained product is in the range of 0.5% to 30% by weight,

[0199] wherein component (a) is selected from the group consisting of compounds having one carboxyl group and two OH groups,

[0200] The polyol (b) is selected from the group consisting of polyester polyols and polyether polyols.

[0201] 29. A polyurethane having a carboxyl group or a derivative thereof obtained or obtainable according to a process for producing a polyurethane having a carboxyl group, the process comprising:

[0202] (i) providing a polyol composition (PC), the polyol composition consisting essentially of the following components:

[0203] a) at least one compound (a) which carries at least one carboxyl group or a derivative thereof and at least one functional group comprising an active hydrogen which is reactive toward isocyanate groups;

[0204] b) at least one polyol compound (b) having an average of 1.5 to 3.5 hydroxyl groups per molecule;

[0205] c) optionally one or more additional active hydrogen compounds (c) different from the compounds (a) and (b);

[0206] d) optionally one or more further additives not containing active hydrogen;

[0207] (ii) contacting the polyol composition (PC) provided in step (i) with at least one isocyanate composition (IC), the at least one isocyanate composition comprising at least one isocyanate (I1) having an average of at least 1.5 isocyanate groups, wherein the NCO group content of the obtained product is in the range of 0.1% to 35% by weight.

[0208] 30. The polyurethane according to embodiment 29, wherein the polyurethane has a carboxyl number ranging from 0.2 mg KOH / g to 50 mg KOH / g.

[0209] 31. A polyurethane according to any one of embodiments 29 or 30, wherein the polyurethane has an NCO content in the range of 0.5 wt. % to 30 wt. %, preferably an NCO group content in the range of 1 wt. % to 25 wt. %, in particular in the range of 1.5 wt. % to 20 wt. %, more preferably in the range of 3 wt. % to 15 wt. %, particularly preferably in the range of 4 wt. % to 15 wt. %.

[0210] The invention is further described by way of examples. The examples relate to practical and in some cases preferred embodiments of the invention and do not limit the scope of the invention. Example

[0211] 1. The materials used are summarized in Table 1 .

[0212] Table 1

[0213]

[0214]

[0215] 2. For Examples 18 and 3 and their COOH-group-free references, the synthesis of the prepolymers is described by way of example.

[0216] 2.1 Example 18 :

[0217] Polyol 5 (420 g) was melted at 60°C. DMBA (25.2 g) and DIBIS (0.06 g) were added and the mixture was heated to 110°C for 30 minutes to obtain a clear solution. The polyol mixture was cooled to 90°C and diisocyanate 1 (154.8 g) was added in one portion. The exothermic behavior of the reaction resulted in a temperature increase to 110°C. The reaction mixture was stirred at 95°C for a further 2 hours. The NCO and viscosity of the resulting product can be found in the summary table.

[0218] 2.2 Example 33

[0219] Polyol 5 (354.4 g) was melted at 60°C. NPG (15 g) and DIBIS (0.05 g) were added and the mixture was heated to 110°C for 30 minutes to obtain a clear solution. The polyol mixture was cooled to 70°C and diisocyanate 1 (130.6 g) was added in one portion. The reaction mixture was stirred at 80°C for 3 hours. The NCO and viscosity of the obtained product can be found in the summary table.

[0220] 2.3 Example 3 :

[0221] DMBA (25.2 g) and DIBIS (0.06 g) were added to Polyol 1 (382.2 g) at 60°C. The mixture was heated to 100°C for 20 minutes to obtain a clear solution. The polyol mixture was cooled to 80°C and diisocyanate 1 (192.6 g) was added in one portion. The exothermic behavior of the reaction resulted in a temperature increase to 126°C. The reaction mixture was stirred at 95°C for a further 2 hours. The NCO and viscosity of the resulting product can be found in the summary table.

[0222] 2.4 Example 22:

[0223] BDO (17.9 g) and DIBIS (0.06 g) were added to Polyol 1 (387 g), and the mixture was heated to 70° C., and diisocyanate 1 (195 g) was added in one portion. The exothermic behavior of the reaction resulted in a temperature increase to 120° C. The reaction mixture was stirred at 80° C. for a further 2 hours. The NCO and viscosity of the obtained product can be found in the summary table.

[0224] 2.5 A series of prepolymers with different compositions were produced. The examples are summarized in Table 2a to Table 2h :

[0225] Table 2a

[0226]

[0227] Table 2b

[0228]

[0229]

[0230] Table 2c

[0231]

[0232] Table 2d

[0233]

[0234] Table 2e

[0235]

[0236] Table 2f

[0237]

[0238] Table 2g

[0239]

[0240]

[0241] Table 2h

[0242]

[0243] The NCO content in % by weight was determined by back titration of the corresponding samples with an excess of di-n-butylamine 1 M in chlorobenzene and 1 molar hydrochloric acid.

[0244] The viscosity was measured at 70 °C using a Brookfield viscometer CV2000+, using cone and plate geometry, spindle 5, for 50 s. -1 The viscosity is measured at a shear rate of 1.

[0245] 3. Stability of prepolymer over time

[0246] In order to monitor the stability of the prepolymers over time, the viscosity and NCO% values ​​of selected freshly synthesized prepolymers and old prepolymers stored under N2 for 6 months were measured.

[0247] The prepolymer is stable within the measurement error range. The corresponding data are summarized in Table 3.

[0248] Table 3

[0249]

[0250] 4. Lamination / delamination experiments :

[0251] As a representative example, the prepolymer according to Example 18 was laminated on a plate made of ether-based expanded thermoplastic polyurethane beads according to WO 2013 / 153190 A1 (Infinergy 230, based on diisocyanate 4, BDO and polyol 1, BASF SE) using steam (steam cabinet molding machine from Kurtz GmbH, K68) (19.5*19.5*1 cm 3 , length, width, height: l*w*h) was melted onto the plate with the help of the following coating equipment: Coatmaster 510; 75μm Spiral doctor blade, at a temperature of 85℃ to 90℃.

[0252] Next, place a piece of cotton canvas (42×20cm 2 , standard cotton tissue, type 10A, Fa. Rocholl) is pressed onto the above expanded thermoplastic polyurethane coated plate.

[0253] The bonded parts were cured at room temperature for >2 days at a controlled air humidity of 65%.

[0254] After that, cut the board into about 3*2*1cm 2 (l*w*h) sheets and placed in different liquid media and kept under stirring at 80°C as shown in Table 2 to examine the stability of the adhesive during its service life and the debonding ability of the adhesive under alkaline conditions (the original concentration was also examined).

[0255] The adhesion between the expanded thermoplastic polyurethane sheet and the fabric was tested by mechanically separating the two substrates (peeling by hand).

[0256] Possible delamination was checked every 5 minutes. The times for easy delamination by hand are summarized in Table 4.

[0257] Table 4: Prepolymers tested between eTPU and cotton canvas (Example 18)

[0258]

[0259]

[0260] As shown in Table 4, no debonding was observed when the bonded material was in contact with hot tap water or a detergent / water mixture (highlighted with an "x" in the table). On the other hand, debonding was observed after 30 minutes of treatment in hot alkaline water. The higher the alkaline concentration, the faster the debonding.

[0261] The same series of experiments were repeated for samples prepared using polyamide 6 (PA6) textiles, resulting in the following data set shown in Table 5:

[0262] Table 5: Prepolymers tested between eTPU and different textiles (Example 18) .

[0263]

[0264] 6. Reference Example Lamination / Delamination

[0265] The demixing behavior of the prepolymer containing COOH groups from demixing experiment 1 was compared with a prepolymer of similar composition without COOH groups (Example 33).

[0266] Debonding experiments were performed according to the procedure described in Delamination Example 1.

[0267] Table 6: Different prepolymers tested between eTPU and cotton canvas

[0268]

[0269]

[0270] As can be seen from Table 6, the prepolymer based on the carboxyl terminated polyester delaminated much faster in the debonding bath of 0.5 M NaOH.

[0271] Polyether-based prepolymers do not undergo any demixing.

[0272] 7. Lamination / delamination experiments using microwaves

[0273] A piece of 3*2*1 cm3 (l*w*h) of laminated expanded thermoplastic polyurethane sheet / cotton bonded by using the prepolymer according to Example 18 was placed in 100 ml of water.

[0274] The samples in the water bath were placed in a Microwave Panasonic inverter NN-SD271S at 950 W for 90 s.

[0275] Afterwards, the cotton fabric can be easily peeled off by hand.

[0276] 8. Debondable Adhesive Embodiment

[0277] EPDM crumb (29.75 g (85% w / w)) and prepolymer according to Example 18 (15% w / w, 5.25 g) were mixed together with the aid of a wooden spatula. The composite material (7*4*1 cm 3 (l*w*h)) was cured at room temperature and 65% controlled air humidity for at least 2 days.

[0278] The obtained composite material has good mechanical stability and elasticity.

[0279] After stirring the composites in alkaline water at 80 °C (3 h:45 min, NaOH concentration of 1 mol / L), the different EPDM crumbs could be easily separated again.

[0280] The same procedure was repeated with cork, wood chips, glass fibers, loose e-TPU beads (Infinergy 230, BASF), loose e-PA beads (produced by the procedure described in WO2021052881 A1), expanded loose e-PP beads (Neopor, BASF), e-TPO (Argilix-O, JSP), expanded loose ePS beads (Styropor) and loose e-TPA beads (produced by the procedure described in WO2017220671 A1). The obtained parts can be debonded in alkaline water to obtain the original material.

[0281] References :

[0282] WO 2019 / 175151 A1

[0283] WO 2018 / 156689 A1

[0284] Ullmanns der technischen Chemie [Ullmann's Encyclopedia of Industrial Chemistry], 4th edition, volume 19, pages 62 to 65 and 306; pages 416 et seq.

[0285] Houben-Weyl, Methoden der Organischen Chemie, Volume XIV / 2, Thieme-Verlag, Stuttgart 1963, p. 60f.

[0286] Gerhard W. Becker and Dietrich Braun, Plastics Handbook, Volume 7, Polyurethanes, Carl Hanser Verlag, Munich, Vienna, 1993

[0287] WO 2007 / 082838 A1

[0288] WO2013 / 153190 A1

[0289] WO2015 / 052265 A1

Claims

1. A method for producing a polyurethane having a carboxyl group, the method comprising the following steps: (i) providing a polyol composition (PC), the polyol composition consisting essentially of the following components: a) at least one compound (a) which carries at least one carboxyl group or a derivative thereof and at least one functional group comprising an active hydrogen which is reactive toward isocyanate groups; b) at least one polyol compound (b), the at least one polyol compound having an average of 1.5 to 3.5 hydroxyl groups per molecule; c) optionally one or more additional active hydrogen compounds (c) different from the compounds (a) and (b); d) optionally one or more further additives not containing active hydrogen; (ii) contacting the polyol composition (PC) provided in step (i) with at least one isocyanate composition (IC), the at least one isocyanate composition comprising at least one isocyanate (I1) having an average of at least 1.5 isocyanate groups, wherein the NCO group content of the obtained product is in the range of 0.1% to 35% by weight.

2. The process according to claim 1, wherein the NCO group content of the obtained product is in the range of 3% to 15% by weight.

3. The method according to claim 1 or 2, wherein the component (a) is selected from the group consisting of compounds having one carboxyl group and one or two functional groups selected from the group consisting of SH, NH and OH groups.

4. The method according to any one of claims 1 to 3, wherein the component (a) is selected from the group consisting of compounds having one carboxyl group and two OH groups.

5. The method according to any one of claims 1 to 4, wherein the content of component (a) in the polyol composition is in the range of 3% to 50%.

6. The method according to any one of claims 1 to 5, wherein the polyol (b) is selected from the group consisting of polyester polyols and polyether polyols. 7 . The process according to claim 1 , wherein the polyol (b) has an average molecular weight Mn of less than 10 000 g / mol.

8. The process according to any one of claims 1 to 7, wherein the isocyanate (I1) is selected from the group consisting of aliphatic diisocyanates, cycloaliphatic diisocyanates and aromatic diisocyanates or aromatic / aliphatic oligomeric or polymeric isocyanates.

9. Polyurethane having carboxyl groups or derivatives thereof obtained or obtainable according to the process according to any one of claims 1 to 8.

10. The polyurethane according to claim 9, wherein the polyurethane has a carboxyl number in the range of 0.2 mg KOH / g to 50 mg KOH / g according to ISO 2114:2000, wherein 70 mL acetone is used as solvent and potassium hydrogen phthalate is used as titrant.

11. The polyurethane according to any one of claims 9 to 10, wherein the NCO content of the polyurethane is in the range of 3% to 15% by weight.

12. Use of a polyurethane obtained by a process according to any one of claims 1 to 6 or a polyurethane according to any one of claims 9 to 11 as an adhesive, as a binder or as a component for preparing polyurethanes.

13. The use according to claim 12, wherein the polyurethane is used as an adhesive for the preparation of consumer goods, industrial goods, building goods, sports equipment or flooring.

14. The use according to claim 12, wherein the polyurethane is used as a binder for binding particles.

15. A method for producing a composite material, wherein the polyurethane obtained by the method according to any one of claims 1 to 8 or the polyurethane according to any one of claims 9 to 12 is used as an adhesive, as a binder or as a component for producing a polyurethane.

16. A method for preparing a composite material comprising at least a first component (C1) and a second component (C2), the method comprising the following steps: (x) providing a first component (C1) and a second component (C2), (y) providing a polyurethane obtained or obtainable according to a process according to any one of claims 1 to 6 or a polyurethane according to any one of claims 7 to 10, and (z) bonding the first component and the second component by means of the polyurethane provided in step (y).

17. The method according to claim 16, wherein the first component (C1) comprises a thermoplastic polymer.

18. The method according to claim 16 or 17, wherein the first component (C1) comprises a foamed thermoplastic polymer.

19. The method according to any one of claims 16 to 18, wherein the second component (C2) comprises a thermoplastic polymer.

20. An article obtained or obtainable by a method according to any one of claims 16 to 19.

21. The article according to claim 20, wherein the article can be disassembled into components (C1) and / or (C2).

22. The article of claim 20 or 21, wherein the article is recyclable.

23. The article according to any one of claims 20 to 22, wherein recycling of the article produces components (C1 ) and / or (C2).

24. The article of any one of claims 20 to 23, wherein the article is a consumer product or a part of a consumer product.

25. A method for disassembling an article obtained or obtainable by a method according to any one of claims 16 to 19, the method comprising the steps of: (A) treating the article with a solution having a pH in the range of 8 to 13 at a temperature in the range of 50°C to 150°C; (B) Recovering components (C1) and / or (C2).

26. A method for disassembling an article obtained or obtainable by a method according to any one of claims 16 to 19, the method comprising the steps of: (A') exposing the article placed in a water bath to microwaves; (B') Recovering components (C1) and / or (C2).

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