R¹ and R² independently of each other each denote a divalent aliphatic, cycloaliphatic or aromatic radical having 1 to 18 C atoms, which can be interrupted by oxygen and/or nitrogen atoms, and R³ represents an alkoxy-terminated polyethylene oxide radical. Compounds having a nonionic hydrophilizing action are also, for example, monofunctional polyalkylene oxide polyether alcohols containing, as a statistical average, > 5 to < 70, preferably > 7 to < 55 ethylene oxide units per molecule, such as are accessible in a manner known per se by alkoxylation of suitable starter molecules (for example in Ullmanns Encyclopadie der technischen Chemie, 4th edition, volume 19, Verlag Chemie, Weinheim p. 31-38).

Suitable starter molecules are, for example, saturated monoalcohols, such as methanol, ethanol, n- propanol, isopropanol, n-butanol, isobutanol, sec-butanol, the isomeric pentanols, hexanols, octanols and nonanols, n-decanol, n-dodecanol, n-tetradecanol, n-hexadecanol, n-octadecanol, cyclohexanol, the isomeric methylcyclohexanols or hydroxymethylcyclohexane, 3-ethyl-3- hydroxymethyloxetane or tetrahydrofurfuryl alcohol, diethylene glycol monoalkyl ethers, such as, for example, diethylene glycol monobutyl ether, unsaturated alcohols, such as allyl alcohol, 1, 1- dimethylallyl alcohol or oleyl alcohol, aromatic alcohols, such as phenol, the isomeric cresols or methoxyphenols, araliphatic alcohols, such as benzyl alcohol, anisyl alcohol or cinnamyl alcohol, secondary monoamines, such as dimethylamine, diethylamine, dipropylamine, diisopropylamine, dibutylamine , b i s-(2-ethylhexyl)-amine, N-methyl- and N-ethylcyclohexylamine or dicyclohexylamine, and heterocyclic secondary amines, such as morpholine, pyrrolidine, piperidine or l H-pyrazole. Preferred starter molecules are saturated monoalcohols. Diethylene glycol monobutyl ether is particularly preferably used as the starter molecule.

Alkylene oxides which are suitable for the alkoxylation reaction are, in particular, ethylene oxide and propylene oxide, which can be employed in the alkoxylation reaction in any desired sequence or also in a mixture.

The polyalkylene oxide polyether alcohols are either pure polyethylene oxide polyethers or mixed polyalkylene oxide polyethers, the alkylene oxide units of which comprise ethylene oxide units to the extent of at least 30 mol%, preferably to the extent of at least 40 mol%. Preferred nonionic compounds are monofunctional mixed polyalkylene oxide polyethers which contain at least 40 mol% of ethylene oxide units and not more than 60 mol% of propylene oxide units.

A combination of nonionic (A4) and ionic (A5) hydrophilizing agents is preferably used for the preparation of the polyurethane (A). Combinations of nonionic and anionic hydrophilizing agents are particularly preferred. The preparation of the aqueous polyurethane (A) can be carried out in one or more stages in a homogenous or, in the case of a multi-stage reaction, partly in a disperse phase. After the polyaddition has been completely or partly carried out, a dispersing, emulsifying or dissolving step is carried out. Thereafter, a further polyaddition or modification is optionally carried out in the disperse phase.

All the processes known from the prior art can be used for the preparation of the polyurethane (A), such as emulsifier-shearing force, acetone, prepolymer mixing, melt emulsification, ketimine and solid spontaneous dispersing processes or derivatives thereof. A summary of these methods is to be found in Methoden der organischen Chemie (Houben-Weyl, supplementary and follow-up volumes to the 4th edition, volume E20, H. Bartl and J. Falbe, Stuttgart, New York, Thieme 1987, p. 1671- 1682). The melt emulsification, prepolymer mixing and the acetone process are preferred. The acetone process is particularly preferred. For the preparation of a polyurethane prepolymer, all or portions of the constituents (A2) to (A5), which contain no primary or secondary amino groups, and a polyisocyanate (A l ) are conventionally initially introduced into the reactor and the mixture is heated up to higher temperatures, preferably in the range of from 50 to 120 °C, optionally diluted with a solvent which is water-miscible but inert towards isocyanate groups, but preferably without a solvent. Suitable solvents are, for example, acetone, butanone, tetrahydrofuran, dioxane, acetonitrile, dipropylene glycol dimethyl ether and 1 -methyl-2-pyrrolidone, which can be added not only at the start of the preparation, but optionally in portions also later. Acetone and butanone are preferred. It is possible to carry out the reaction under normal pressure or increased pressure, e.g. above the normal pressure boiling temperature of a solvent, such as, for example, acetone. The catalysts known for acceleration of the isocyanate addition reaction, such as, for example, triethylamine, l ,4-diazabicyclo-[2,2,2]-octane, dibutyltin oxide, tin dioctoate or dibutyltin dilaurate, tin bis-(2-ethylhexanoate) or other organometallic compounds, can furthermore be also initially introduced or metered in later. Dibutyltin dilaurate is preferred.

The constituents (Al), (A2), optionally (A3) and (A4) and/or (A5), which contain no primary or secondary amino groups, which optionally have not yet been added at the start of the reaction are then metered in. In the preparation of the polyurethane prepolymer, the ratio of the substance amounts of isocyanate groups to isocyanate-reactive groups is > 0.90 to < 3, preferably > 0.95 to < 2.5, particularly preferably > 1.05 to < 2.0. The reaction of components (Al) to (A5) takes place partially or to completion, but preferably to completion, with respect to the total amount of isocyanate-reactive groups of the part of (A2) to (A5) which contains no primary or secondary amino groups. The degree of conversion is conventionally monitored by monitoring the NCO content of the reaction mixture. For this, either spectroscopic measurements, for example infrared or near infrared spectra, determinations of the refractive index or chemical analyses, such as titrations of samples taken, can be carried out. Polyurethane prepolymers which contain free isocyanate groups are obtained in substance or in solution.

After or during the preparation of the polyurethane prepolymers from (Al) and (A2) to (A5), partial or complete salt formation of the groups having an anionic and/or cationic dispersing action takes place, if this has not yet been carried out in the starting molecules. In the case of anionic groups, bases, such as ammonia, ammonium carbonate or ammonium bicarbonate, trimethylamine, triethylamine, tributylamine, diisopropylethylamine, dimethylethanolamine, diethylethanolamine, triethanolamine, potassium hydroxide or sodium carbonate, are employed for this, preferably triethylamine, triethanolamine, dimethylethanolamine or diisopropylethylamine. The substance amount of the bases is between 50 and 100 %, preferably between 60 and 90 % of the substance amount of the anionic groups. In the case of cationic groups, sulfuric acid dimethyl ester or succinic acid are employed. If only nonionically hydrophilized compounds (A5) with ether groups are used, the neutralization step is omitted. The neutralization can also be carried out at the same time as the dispersing, in that the dispersing water already contains the neutralizing agent. Possible aminic components are (A2), (A3) and (A4) with which still remaining isocyanate groups can optionally be reacted. This chain lengthening in this context can be carried out either in a solvent before the dispersing, during the dispersing or in water after the dispersing. If aminic components are employed as (A4), the chain lengthening is preferably carried out before the dispersing. The aminic components (A2), (A3) or (A4) can be added to the reaction mixture in a form diluted with organic solvents and/or with water. Preferably, > 70 % by weight to < 95 % by weight of solvent and/or water is employed. If several aminic components are present, the reaction can be carried out in succession in any desired sequence or simultaneously by addition of a mixture.

For the purpose of preparation of the polyurethane dispersion (A), the polyurethane prepolymers are either introduced into the dispersing water, optionally under high shearing forces, such as, for example, vigorous stirring or using a jet disperser, or, conversely, the dispersing water is stirred into the prepolymer. The increase in molecular weight by reaction of isocyanate groups which may be present with components (A2), (A3) can then be carried out, if this has not yet taken place in the homogeneous phase. The amount of polyamine (A2), (A3) employed depends on the unreacted isocyanate groups still present. Preferably, > 50 to < 100 %, particularly preferably > 75% to < 95 % of the substance amount of isocyanate groups are reacted with polyamines (A2), (A3). The organic solvent can optionally be distilled off. The dispersions have a solids content of from > 10 to < 70 % by weight, preferably > 25 to < 65 % by weight and particularly preferably > 30 to < 60 % by weight.

The polyurethane dispersions can be employed by themselves or with known binders, auxiliary substances and additives, in particular light stabilizers, such as UV absorbers and sterically hindered amines (HALS), furthermore antioxidants, fillers and lacquer auxiliary substances, for example antisettling agents, defoaming and/or wetting agents, flow agents, reactive diluents, plasticizers, catalysts, auxiliary solvents and/or thickeners and additives, such as, for example, dispersions, pigments, dyestuffs or matting agents. In particular, combinations with polyurethane dispersions or polyacrylate dispersions, which can optionally also be hydroxy- functional, are possible without problems. The additives can be added to the PU dispersions directly before processing. However, it is also possible to add at least a portion of the additives before or during the dispersing of the binder or binder/crosslinking agent mixture. The choice and the metering of these substances which can be added to the individual components and/or the total mixture, are known to the person skilled in the art.

In a further embodiment of the process according to the invention, the adhesive comprises a polyurethane hot melt adhesive. Such adhesives are also called hot melts. They are preferably hot melt adhesive films or reactive hot melt adhesives. For reactive hot melt adhesives, linear polyesters and/or poly ether polyols are preferably used in combination with an excess of polyisocyanates, preferably diisocyanates.

The advantages of this product class lie above all in the absence of solvents, the possibility of applying the products hot with relatively low viscosities and nevertheless of obtaining high initial strengths and, because of the further reaction with moisture, of obtaining after a relatively short time adhesive bonds with a very high heat resistance far above the application temperatures and excellent resistances to solvents. An example for a reactive hot melt adhesive comprises:

A') at least one aromatic, aliphatic, araliphatic and/or cycloaliphatic isocyanate, preferably with a content of free NCO groups of from 5 to 60 wt.% (based on A') and

B') a polyol or polyol mixture containing at least one polyester polyol.

The preparation of the compositions is preferably carried out, for example, by a procedure in which the polyols B') and the isocyanates A') are mixed, the ratio of A' to B' being chosen such that the molar ratio of NCO to OH is > 1, preferably from > 1.2 to < 4.0, particularly preferably from > 1.3 to < 3.0, and the homogeneous mixture is filled into containers or is stirred until a constant NCO value is obtained and then filled into containers. > 60 °C to < 150 °C, preferably > 80 °C to < 130 °C are chosen as the preferred reaction temperature. The preparation of the formulations can also be carried out continuously in a cascade of stirred tanks or in suitable mixing units, such as, for example, rapidly rotating mixers by the rotor-stator principle or a static mixer.

It is also possible to modify the polyols or polyol mixture B') or a part thereof with a deficit of A') and, when the reaction has ended, to react the polyols containing urethane groups with an excess of A') to give a composition containing isocyanate groups.

It is likewise possible to carry out the reaction of the polyols B') with the isocyanates A') in the presence of up to 5 % by weight of, for example, trimers of aliphatic and/or aromatic diisocyanates, such as, for example, HDI, or to add such trimers when the prepolymerization has ended. In a further embodiment of the process according to the invention, the adhesive includes a moisture-curing 1 C PU adhesive. It is likewise possible to formulate the prepolymer as a 2C PU adhesive together with a component containing OH groups.

Monomeric diisocyanates for the preparation of the prepolymers are those aromatic, aliphatic or cycloaliphatic di- or triisocyanates of which the molecular weight is less than 500 g/mol. Examples of suitable aromatic diisocyanates are all the isomers of toluylene-diisocyanate (TDI), either in the isomerically pure form or as a mixture of several isomers, naphthalene-l,5-diisocyanate (NDI), naphthalene- 1 ,4-diisocyanate (NDI), diphenylmethane-4,4'-diisocyanate (MDI), diphenylmethane- 2,4'-diisocyanate and mixtures of 4,4'-diphenylmethane-diisocyanate with the 2,4' isomer, xylylene-diisocyanate (XDI), 4,4'-diphenyldiethylmethane-diisocyanate, di- and tetraalkyl- diphenylmethane-diisocyanate, 4,4'-dibenzyl-diisocyanate, 1,3-phenylene-diisocyanate, 1,4- phenylene-diisocyanate. Examples of suitable cycloaliphatic diisocyanates are the hydrogenation products of the abovementioned aromatic diisocyanates, such as e.g. 4,4'-dicyclohexylmethane- diisocyanate, isophorone-diisocyanate, cyclohexane-l ,4-diisocyanate, hydrogenated xylylene- diisocyanate (H6XDI), l-methyl-2,4-diisocyanato-cyclohexane, m- or p-tetramethylxylylene- diisocyanate (m-TMXDI, p-TMXDI) and dimer fatty acid diisocyanate. Examples of aliphatic diisocyanates are tetramethoxybutane-l,4-diisocyanate, butane-l,4-diisocyanate, hexane-1,6- d i i s o c y a n a t e ( H D I ) , 1 , 6-diisocyanato-2,2,4-trimethylhexane, 1 , 6-diisocyanato-2,4,4- trimethylhexane, lysine-diisocyanate and 1,12-dodecane-diisocyanate (CI 2 DI).

Polyisocyanates which are formed by trimerization or oligomerization of diisocyanates or by reaction of diisocyanates with polyfunctional low molecular weight compounds containing hydroxyl or amino groups are also suitable as isocyanates which are at least trifunctional. Commercially obtainable products are, for example, trimerization products of the isocyanates HDI, MDI or IPDI as a biuret, uretdione or carbodiimide. In particular, isocyanates which contain isocyanate groups of different functionality can also be employed.

Examples of such aromatic asymmetric diisocyanates are all the isomers of toluylene-diisocyanate (TDI), either in the isomerically pure form or as a mixture of several isomers, naphthalene-1 ,5- diisocyanate (NDI), naphthalene-l,4-diisocyanate (NDI), diphenylmethane-2,4'-diisocyanate (MDI) and mixtures of 4,4'-diphenylmethane-diisocyanate with the 2,4'-MDI isomer and 1 ,3- phenylene-diisocyanate. Examples of suitable cycloaliphatic asymmetric diisocyanates are e.g. isophorone-diisocyanate, l-methyl-2,4-diisocyanato-cyclohexane or hydrogenation products of the abovementioned aromatic diisocyanates, in particular hydrogenated MDI in isomerically pure form, preferably hydrogenated 2,4'-MDI. Examples of aliphatic asymmetric diisocyanates are 1,6- diisocyanato-2,4,4-trimethylhexane and lysine-diisocyanate.

Aromatic isocyanates are particularly preferably suitable as isocyanates. These have a high reactivity and a rapid rate of reaction in the adhesive.

In this context, a large number of higher molecular weight polyhydroxy compounds can be used as polyols for the synthesis of the PU prepolymer. Suitable polyols are preferably polyhydroxy compounds with two or three hydroxyl groups per molecule in the molecular weight range of from 200 to 4,000 g/mol, preferably in the range of from 400 to 2,000 g/mol. Examples are di- and/or trifunctional polypropylene glycols, and random and/or block copolymers of ethylene oxide and propylene oxide can also be employed. A further group of polyethers to be employed are the polytetramethylene glycols (poly(oxytetramethylene) glycol, poly-THF), which are prepared e.g. by acid polymerization of tetrahydrofuran.

Those polyesters which can be prepared by condensation of di- or tricarboxylic acids, such as e.g. adipic acid sebacic acid, glutaric acid, azelaic acid, suberic acid, undecanedioic acid, dodecanedioic acid, 3,3-dimethyl-glutaric acid, terephthalic acid, isophthalic acid, hexahydrophthalic acid, or mixtures thereof, with low molecular weight diols or triols, such as e.g. ethylene glycol, propylene glycol, diethylene glycol, tri ethylene glycol, dipropylene glycol, 1 ,4-butanediol, 1,6-hexanediol, 1,8-octanediol, 1 , 1 0-decanediol, 1,12-dodecanediol, dimer fatty alcohol, glycerol, trimethylolpropane or mixtures thereof, are furthermore suitable as polyols. A further group of the polyols which are to be employed according to the invention are the polyesters based on ε- caprolactone, also called polycaprolactones. In this context, the molecular weight of such polyester polyols should be below 2,000 g/mol.

However, polyester polyols of oleochemical origin can also be used. Such polyester polyols can be prepared, for example, by complete ring-opening of epoxidized triglycerides of a fatty acid mixture containing at least partly olefinically unsaturated fatty acid with one or more alcohols having 1 to 12 C atoms and subsequent partial transesterification of the triglyceride derivatives to give alkyl ester polyols having 1 to 12 C atoms in the alkyl radical. Further suitable polyols are polycarbonate polyols, dimer diols and castor oil and derivatives thereof. The hydroxy-functional polybutadienes such as are obtainable e.g. under the trade name Poly-bd can also be employed as polyols for the compositions according to the invention.

Linear and/or weakly branched acrylic ester copolymer polyols which can be prepared, for example, by free radical copolymerization of acrylic acid esters or methacrylic acid esters with hydroxy-functional acrylic acid and/or methacrylic acid compounds, such as hydroxyethyl (meth)acrylate or hydroxypropyl (meth)acrylate, are furthermore suitable as polyols. Because of this preparation procedure, the hydroxyl groups in these polyols are as a rule randomly distributed, so that these are either linear or weakly branched polyols with an average OH functionality. Although the difunctional compounds are preferred for the polyols, polyols of higher functionality can also be used, at least in minor amounts. The polyols should preferably be predominantly liquid. The molecular weight should in general be below 2,000 g/mol, in particular below 1 ,200 g/mol. In this context, it is preferable if diols or mixtures thereof are employed. Contents of triols of higher functionality can also be employed. In a particular embodiment, polyether diols or polyalkylene diols with a molecular weight of < 2,000 g/mol are employed. In another embodiment, up to 25 wt.% of trifunctional alcohols, in particular oleochemical polyols or polyethers, are additionally employed.

The reaction of the monomeric diisocyanates with the polyols in this context is carried out in a manner known per se, optionally with the addition of aprotic solvents. In order to avoid the formation of higher oligomers, it is advantageous to employ an excess of diisocyanates in relation to the diols. The formation of more highly branched prepolymers should largely be avoided. In one embodiment, when the reaction has ended the reaction product can be freed as far as possible from monomeric diisocyanate. The purification step can be carried out by processes known per se. For example, the monomeric isocyanate can be removed by selective extraction, for example using supercritical carbon dioxide or other supercritical aprotic solvents. Preferably, if volatile monomeric diisocyanates are used, such as TDI, TMXDI, IPDI, XDI, MDI, the excess monomeric diisocyanate can be removed from the reaction mixture by distillation. For this, the distillation is preferably carried out in vacuo with the aid of a thin layer evaporator or a thin film evaporator. Such distillation processes are described in the literature. The polyurethane adhesives used according to the invention can furthermore contain auxiliary substances, which in the case of 2C adhesives can be added in full or in part to the polyol component, and in the case of 1C adhesives they are admixed to the prepolymer.

These are understood as meaning substances which as a rule are added in order to modify the properties of the essential components in the desired direction, e.g. to adapt their processability, storage stability and also use properties to the concrete field of use. Examples of these are finely divided fillers, flow agents, deaerating agents, thixotropy agents, catalysts, resins, antiageing agents, stabilizers, dyestuffs, adhesion promoters and wetting agents.

If the polyurethane prepolymer is built up predominantly from polyether units, antioxidants, optionally in combination with UV stabilizers, are chiefly necessary. If essential constituents of the polyurethane prepolymer consist of polyester units, hydrolysis stabilizers, e.g. of the carbodiimide type, are preferably employed.

The choice of these stabilizers depends on the one hand on the main components of the composition, and on the other hand on the application conditions and the expected exposure to stresses of the cured product.

The PU prepolymer can additionally contain a resin. These resins are liquid to solid organic products for which a more or less broad distribution of the relative molecular weight is characteristic. They usually have an amorphous structure. The known resins can be used, whether of natural or synthetic origin. The natural resins can be of either plant or animal origin. Examples of these are shellac and colophony resins, such as tall oil resin, balsam resin or root resin. Not only the natural resins, but also derivatives thereof are suitable, such as hydrogenated, esterified or neutralized resins. The synthetic resins are in general obtained by polymerization or polycondensation. Examples of these are urea, melamine, hydrocarbon, terpene, coumarone/indene, furan, aldehyde, ketone, ketone/aldehyde, phenolic, alkyd, glycerol ester, polyester, epoxy, polyamide and isocyanate resins. These resins can contain isocyanate-reactive groups, or they contain no such groups.

Adhesives can be formulated from the PU prepolymers. In this context it is possible to prepare 1C PU adhesives, these then containing 95.5 to 70 wt.% of the polyurethane prepolymer which contains NCO groups and is suitable according to the invention, and 0.5 to 30 wt.% of drying and/or semi-drying oils. These 1 C PU adhesives can optionally also contain up to 25 wt.% of additives and auxiliary substances. In particular, it is expedient for them to contain 0.01 to 2 % of catalysts, where the catalysts can be contained for the polyurethane reaction, and additionally catalysts for a crosslinking reaction of the drying or semi-drying oils. In a preferred embodiment, 2 to 20 wt.%, based on the prepolymer, of drying oils are present.

2C PU adhesives can furthermore be formulated from the PU prepolymers, which have NCO groups and are suitable according to the invention, together with the drying oils. In this context, the NCO-reactive PU prepolymer component can optionally contain up to 25 wt.% of additives and auxiliary substances, but in particular these are added to the component containing OH groups.

The amount of component containing OH groups should be up to 50 wt.%, based on the PU prepolymer, an NCO:OH ratio which has a low excess of isocyanate groups being chosen. For example, the NCO:OH ratio should be from 1.2 to 2, in particular from 1.05 to 1.5. These two components are stored separately until used, and are mixed directly before use and then used as an adhesive.

Liquid polyols with a functionality of from 2 to 5 can be chosen as the component containing OH groups. These can be one or more of the polyols mentioned above. In this context, however, the molecular weight can be higher, and can be, for example, up to 10,000 g/mol. Preferably, these polyols have a functionality of more than two and optionally increase the crosslinking density. This component can likewise contain resins containing OH groups. The corresponding functional groups are to be taken into account in the amount of isocyanate groups.

The viscosity of the adhesive according to the invention should be between 100 to 100,000 mPas (measured in accordance with EN ISO 2555, Brookfield viscometer), measured at the application temperature. This should be, in particular, between 15 and 40 °C, and in particular this viscosity should exist at room temperature (20 - 30 °C).

The PU adhesives according to the invention can be applied to various substrates. Due to the low viscosity, they can be processed at room temperature. They flow well on to the substrate and can be applied in a thin layer. The adhesives crosslink by moisture from the atmosphere or by the second component containing OH groups. In this context, the crosslinking can be accelerated by elevated temperature.

In a further embodiment of the process according to the invention, a pressure of from > 0.1 bar to < 2 bar is exerted by the contracted enclosing flexible casing on the first and second component which have been joined together. Preferably, the pressure is in a range of from > 0.5 bar to < 1 bar. This is sufficient to fix an adhesive bond. In a further embodiment of the process according to the invention, several first and second components which have been joined together are enclosed by the enclosing flexible casing and, after the action of the external stimulus, the contracted enclosing flexible casing is portioned into individual packages each with a first and second component which have been joined together. This has the advantage that when the process is used, each component which has been joined together is not contracted individually in the device, but several components which have been joined together can be contracted at the same time. In order to separate the several components which have been joined together from one another, a separating device, such as, for example, a cutting edge, is used, which separates through the contracted enclosing flexible casing after each component which has been joined together.

The present invention also provides a component which has been joined together, obtainable by a process according to the invention, wherein an enclosing flexible casing at least partly encloses the component which has been joined together and a pressure acts at least partly on adhesive between a first and second component. Details have already been described in connection with the process according to the invention, so that reference is made to these in order to avoid repetitions.

In one embodiment of the component according to the invention, the component which has been joined together is footwear. In particular, the footwear can be a shoe or a boot.

The invention is explained in more detail in the following with the aid of a preferred embodiment with reference to the attached drawings. The figures show:

FIG. 1 a first and a second component

FIG. 2 a first and a second component on to which an adhesive has been applied

FIG. 3 a first and the second component which are joined together

FIG. 4 an enclosing flexible casing which encloses the components which have been joined together

FIG. 5 an assembled component which is surrounded by a one-part contracted enclosing flexible casing

FIG. 6 an assembled component which is surrounded by a two-part contracted enclosing flexible casing

FIG. 7 an item of footwear which is surrounded by a contracted enclosing flexible casing

FIG. 1 shows a diagram of a first 1 and a second component 2 which are to be joined together. The first 1 and the second component 2 are provided for further treatment. An adhesive 3 is applied in FIG. 2 to in each case a facing side of the first 1 and the second component 2. It is also conceivable for the adhesive to be applied either only to the first 1 or to the second component 2. An adhesive based on a polyurethane dispersion or a polyurethane hot melt adhesive is preferably used as the adhesive. It can be seen in FIG. 3 how the first 1 and the second component 2 have been joined together and how they are at least partly bonded to one another by the adhesive 3.

According to the invention, in FIG. 4 a component which has been joined together is placed in an enclosing flexible casing. This enclosing flexible casing 4 is constructed as one part in FIG. 5 and can be a vacuum packaging, a shrink film or a film. The enclosing flexible casing 4 can be made of a thermoplastic, for example polyamide, polyethylene, polyolefins, PVDF, PVC, PTFE, and/or of a composite film.

In a device which is not shown, the enclosing flexible casing 4 is contracted by an external stimulus, so that the enclosing flexible casing 4 draws itself around the assembled component. In this context, an external stimulus consists of an evacuation of the air in the enclosing flexible casing 4 and/or a heat treatment of the outside of the enclosing flexible casing 4.

A contracted one-part enclosing flexible casing 4 is shown in FIG. 5. Due to the contraction of the enclosing flexible casing 4, a pressure acts on the first 1 and the second component 2. In this context, a pressure which is sufficient to fix the first 1 and the second component 2 is generated. Furthermore, due to the enclosing flexible casing, a device for pressing the first 1 and the second component 2 is saved, since the assembled component remains in the enclosing flexible casing 4, and the adhesive 3 can achieve a sufficiently high cohesive strength before the enclosing flexible casing 4 is removed.

Due to the contraction of the enclosing flexible casing 4, a pressure of from 0.1 to 2 bar is built up. It can furthermore be seen that the opening of the enclosing flexible casing 4 has been welded so that no environmental influences, for example dirt particles or air, can enter from the outside into the enclosing flexible casing 4.

A multi-part contracted enclosing flexible casing 4 is shown in FIG. 6. This has the advantage that, for example, in the device which is not described and shown, several assembled components can be fed simultaneously to an external stimulus. The assembled components can then be portioned with the aid of a separating device in the device, for example a cutting edge, into individual packages each with a first 1 and second component 2 which has been joined together. In a multi-part contracted enclosing flexible casing 4, a pressure also acts on the first 1 and second component 2 so that the adhesive 3 can reach a sufficiently high cohesive strength. An example of the use of the process is shown in FIG. 7. In an item of footwear 5, a sole has been glued on to the upper. It can be seen how the contracted enclosing flexible casing 4 has drawn itself around the item of footwear 5. As a result, a sufficient pressure acts on the upper and the sole, so that the adhesive 3 can reach a sufficient cohesive strength. A device for pressing and the associated waiting time can thus be dispensed with. The item of footwear 5 can furthermore be delivered in the enclosing flexible casing 4, so that repackaging can be omitted.

Claims

1. Process for joining together at least two components (1, 2), comprising the steps: provision of a first (1) and a second component (2); application of an adhesive (3) to the first (1) and/or second component (2); joining together of the first (1) and second component (2), the first (1) and second component (2) being at least partly bonded to one another by the adhesive (3); introduction of the first (1) and second component (2) into a flexible casing (4); exertion of pressure on the first (1) and second component (2), the pressure acting at least partly on the adhesive (3) between the first (1) and second component (2), and subsequent storage of the first (1) and second component (2) in the contracted flexible casing for a period of at least 1 minute; the pressure being exerted such that a flexible casing (4) at least partly enclosing the first (1) and second component (2) is contracted by an external stimulus and the external stimulus being based on a heat treatment and/or on an evacuation of the enclosing flexible casing (4).

2. Process according to claim 1 , wherein the first component (1) comprises a shoe sole and the second component (2) comprises a shoe upper.

3. Process according to claim 1, wherein the storage of the first (1) and second component (2) takes place for a period of at least 5 minutes.

4. Process according to claim 1, wherein a vacuum packaging is used as the enclosing flexible casing (4).

5. Process according to claim 5, wherein a shrink film, shrink hood and/or a shrink tube is used as the enclosing flexible casing (4).

6. Process according to claim 1, wherein the adhesive (3) comprises an aqueous polyurethane dispersion.

7. Process according to claim 1, wherein the adhesive (3) comprises a polyurethane hot melt adhesive.

8. Process according to claim 1, wherein the adhesive (3) is a moisture-curing 1C PU adhesive or a 2C PU adhesive.

9. Process according to claim 1, wherein a pressure of from > 0.1 bar to < 2 bar is exerted by the contracted enclosing flexible casing (4) on the first (1) and second component (2) which have been joined together.

10. Process according to claim 1 , wherein several first (1) and second components (2) which have been joined together are enclosed by the enclosing flexible casing (4) and, after the action of the external stimulus, the contracted enclosing flexible casing (4) is portioned into individual packages each with a first (1) and second component (2) which have been joined together.

11. Component which has been joined together, obtainable by a process according to claim 1, wherein an enclosing flexible casing (4) at least partly encloses the component which has been joined together and a pressure acts at least partly on adhesive (3) between a first (1) and second component (2).

12. Component which has been joined together according to claim 11, wherein the component which has been joined together is an item of footwear (5).