EP1747242A1

EP1747242A1 - Aqueous polyurethane dispersions and use thereof as adhesives

Info

Publication number: EP1747242A1
Application number: EP05737724A
Authority: EP
Inventors: Wolfgang Arndt; Wolfgang Henning; Jürgen Meixner; Thomas MÜNZMAY; Ralf Werner
Original assignee: Bayer MaterialScience AG
Current assignee: Bayer Intellectual Property GmbH
Priority date: 2004-05-11
Filing date: 2005-04-28
Publication date: 2007-01-31
Also published as: RU2006143542A; US20050256261A1; DE102004023768A1; UA85879C2; AU2005243509A1; CN1984937B; CN1984937A; JP2007537310A; WO2005111107A1; BRPI0511074A; CA2566036A1; JP4897671B2; RU2385331C2; KR20070006941A; MXPA06012892A

Abstract

The invention relates to novel polyurethane and polyurethane-polyurea dispersions, to a method for producing such dispersions, and to their use as adhesives.

Description

Aqueous polyurethane dispersions and their use as an adhesive

The present invention relates to new polyurethane or polyurethane-polyurea dispersions, a process for producing these dispersions and their use as an adhesive.

The preparation of aqueous polyurethane or polyurethane-polyurea dispersions is known prior art (e.g. D. Dieterich, Houben-Weyl: Methods of Organic Chemistry, Volume E20, pp. 1670-81 (1987)).

As described in US Pat. No. 2,968,575, stable or aqueous polyurethane or. Polyurethane-polyurea dispersions initially used external emulsifiers to disperse and stabilize the polymers in water. It turns out, however, that the high content of external emulsifiers, which is necessary for the production of storage-stable, aqueous dispersions, negatively influences the possible uses of such products, since these emulsifiers bring about a high degree of hydrophilicity and sensitivity of the products to water.

In this regard, polyurethane or polyurethane-polyurea dispersions with chemically bound hydrophilic centers as emulsifiers clearly show an improvement. The built-in, hydrophilic centers can be cationic groups (eg DE-A 6 40 789), anionic groups (eg DE-A 14 95 745) and / or non-ionic groups (eg DE-A 23 14 512) ,

Aqueous polyurethane or polyurethane-polyurea dispersions with the built-in, hydrophilic centers mentioned have characteristic advantages and disadvantages. So are Polyurethane or. Polyurethane-polyurea dispersions that are hydrophilized by ionic groups are practically insensitive to high temperatures up to the boiling point due to their salt character. Nonionic, hydrophilized dispersions, on the other hand, coagulate when heated to temperatures above approx. 60 ° C. In contrast, non-ionically hydrophilized dispersions are stable against freezing and electrolytes, whereas ionically hydrophilized dispersions are not stable under these conditions.

The teaching of DE-A 26 51 506 shows a way to avoid the disadvantages of the above-mentioned hydrophilizing groups by combining ionic and nonionic hydrophilic groups. However, polyurethane-polyurea dispersions according to DE-A 26 51 506 have the disadvantage that they are less suitable as an adhesive.

A teaching on the production of aqueous polyurethane or polyurethane-polyurea dispersions, which are particularly suitable as adhesives according to the thermal activation method described for example in DE-A 28 04 609, EP-A 259 679 and DE-A 37 28 140. The aqueous polyurethane-polyurea dispersions disclosed there can only be produced by the so-called acetone process. However, this process involves the use of large amounts of organic solvents as auxiliary solvents, which has to be removed by distillation after the preparation of the polyurethane or polyurethane-polyurea dispersions.

DE-A 37 35 587 describes the solvent-free production of polyurethane or polyurethane-polyurea dispersions which are suitable as adhesives. However, the two-stage manufacturing process disclosed there proves that it cannot be carried out in practice or can only be carried out with great effort. It also shows that the dispersions for the thermal activation process have activation temperatures that are too high. In the thermal activation process, the workpieces are coated with the adhesive in a first step. After the solvent or water has evaporated, a tack-free adhesive film is obtained. This is by heating z. B. activated with an infrared heater. The temperature at which the adhesive film becomes sticky is called the activation temperature. In general, the lowest possible activation temperature of 40 to 60 ° C is sought, since at higher activation temperatures an unfavorably high energy expenditure is required and manual joining becomes difficult or even impossible.

A way of producing aqueous polyurethane or polyurethane-polyurea dispersions, which are particularly suitable as an adhesive by the thermal activation process, is disclosed, for example, by DE-A 101 52 405. There, by using special polyester polyols which contain aromatic metal sulfonate groups, aqueous polyurethane or polyurethane-polyurea dispersions with good activatability at 50 to 60 ° C. can be obtained. However, these polyesters containing aromatic metal sulfonate groups are difficult to access or are very expensive due to the dicarboxylic acids containing metal sulfonate or sulfonic acid groups which are necessarily to be used as raw materials.

A disadvantage of the methods of the prior art is that the dispersion adhesives do not have sufficient initial heat resistance.

The object of the present invention was therefore to provide new polyurethane or polyurethane urea dispersion adhesives which have a sufficiently high initial heat resistance.

Surprisingly, it has now been found that the following aqueous polyurethane or polyurethane-polyurea dispersions according to the invention are outstandingly suitable as adhesives in the thermal activation process. The present invention relates to aqueous polyurethane or polyurethane-polyurea dispersions which have both ionic or potentially ionic groups and nonionic groups, the ionic or potentially ionic groups having a difunctional polyol component which additionally 0.5 contains up to 2 mol of sulfonic acid or sulfonate groups per molecule, and the nonionic groups are introduced into the polymer structure via one or more mono-functional compounds in the sense of the isocyanate polyaddition reaction with an ethylene oxide content of at least 50% by weight and a molecular weight of at least 400 daltons and the dispersion contains 0.1 to 7.5% by weight of an emulsifier not chemically bound to the polymer.

The present invention furthermore relates to a process for producing the aqueous polyurethane or polyurethane-polyurea dispersions according to the invention, characterized in that

A) di- or higher-functional polyols with a molecular weight of 400 to 5000 daltons,

B) optionally di- or higher-functional polyol components with a molecular weight of 62 to 399 daltons,

C) one or more mono-functional compounds in the sense of the isocyanate polyaddition reaction with an ethylene oxide content of at least 50% by weight and a molecular weight of at least 400 Daltons and

D) one or more difunctional polyol components which additionally contain 0.5 to 2 mol of sulfonic acid or sulfonate groups per molecule

E) one or more di- or polyisocyanate components

be converted into an isocyanate-functional prepolymer and then

F) 0.1 to 7.5% by weight of an emulsifier which has no groups reactive toward isocyanate groups and, if appropriate, a neutralizing agent for converting free acid groups from structural component D) into their ionic form, the isocyanate-containing melt is dispersed with water and chain extension by adding an aqueous solution of

G) amino functional components with a functionality of 1 to 3. The aqueous polyurethane or polyurethane-polyurea dispersions according to the invention are distinguished by low activation temperatures in the range from 50 to 60 ° C., very good initial heat resistance of <10 mm min, preferably <5 mm / min, particularly preferably from 0 to 2 mm / min and high heat levels. In addition, they show excellent adhesion to a wide variety of substrates such as wood, leather, textiles, different qualities of polyvinyl chloride (hard, soft PVC), to rubbers or polyethylene vinyl acetate.

Suitable di- or higher-functional polyols A) are compounds with at least two isocyanate-reactive hydrogen atoms and an average molecular weight of 400 to 5,000 daltons. Examples of suitable structural components are polyethers, polyesters, polycarbonates, polylactones and polyamides. Preferred compounds have 2 to 4, particularly preferably 2 to 3 hydroxyl groups, such as those described for. B. for the production of homogeneous and cellular polyurethanes are known per se and as e.g. in DE-A 28 32 253, pages 11 to 18. Mixtures of various such compounds are also possible according to the invention.

Suitable polyester polyols are, in particular, linear polyester diols or also weakly branched polyester polyols, as are known in a known manner from aliphatic, cycloaliphatic or aromatic di- or polycarboxylic acids or their anhydrides, such as e.g. Amber, glutaric, adipic, pimeline, cork, azelaic, sebacic, nonandicarboxylic, decanedicarboxylic, terephthalic, isophthalic, o-phthalic, tetrahydrophthalic, hexahydrophthalic or trimellitic acid and acid anhydrides, such as o-phthalic, trimellitic or succinic anhydride or their mixtures with polyhydric alcohols, such as Ethanediol, di-, tri-, tetraethylene glycol, 1, 2-propanediol, di-, tri-, tetrapropylene glycol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, pentane diol-1,5, hexanediol-1,6, 2,2-dimethyl-1,3-propanediol, 1,4-dihydroxycyclohexane, 1,4-dimethylolcyclohexane, octanediol-1,8, decanediol-1,10, Dodecanediol-1,12 or mixtures thereof, optionally with the use of higher functional polyols such as trimethylolpropane, glycerol or pentaerythritol. Cycloaliphatic and / or aromatic di- and polyhydroxyl compounds are of course also suitable as polyhydric alcohols for the production of the polyester polyols. Instead of the free polycarboxylic acid, the corresponding polycarboxylic acid anhydrides or corresponding polycarboxylic acid esters of lower alcohols or mixtures thereof can also be used to produce the polyesters.

Of course, the polyester polyols can also be homopolymers or copolymers of lactones, preferably by adding lactones or lactone mixtures, such as butyrolactone, ε-caprolactone and / or methyl-ε-caprolactone, to the suitable di- and / or higher-functional starter molecules , such as those described above as structural components for polyester poly ole called low molecular weight, polyhydric alcohols can be obtained. The corresponding polymers of ε-caprolactone are preferred.

Polycarbonates containing hydroxyl groups are also suitable as polyhydroxyl components, e.g. those which are obtained by reacting diols such as 1,4-butanediol and / or 1,6-hexanediol with diaryl carbonates, e.g. Diphenyl carbonate, dialkyl carbonates, such as. B. dimethyl carbonate or phosgene can be produced.

Suitable polyether polyols are, for example, the polyadducts of styrene oxides, ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide, epichlorohydrin, and their mixed addition and graft products, and those by condensation of polyhydric alcohols or mixtures thereof and those by alkoxylation of polyhydric alcohols, Amines and amino alcohols obtained polyether polyols. Polyether polyols suitable as build-up components A) are the homo-, copolymers and graft polymers of propylene oxide and ethylene oxide, which are obtained by addition of the epoxides mentioned to low-molecular diols or triols, as mentioned above as build-up components for polyester polyols, or to higher-functionality, low-molecular weight ^" polyols ^" for example pentaerythritol odeϊ ^'sugar or accessible to water.

Preferred di- or higher-functional polyols A) are polyester polyols, polylactones and polycarbonates. Largely linear polyester polyols which contain adipic acid and 1,4-butanediol and / or 1,6-hexanediol as structural components are particularly preferred. Largely linear polycaprolactones are also particularly preferred. For the purposes of this invention, a largely computational functionality based on hydroxyl groups of 1.9 to 2.35, preferably of 1.95 to 2.2 and particularly preferably of 2 is considered to be largely linear.

Di- or higher-functional polyol components with a molecular weight of 62 to 399 daltons which are suitable as build-up component B) are the products listed under A), provided they have a molecular weight of 62 to 399 daltons. Further suitable components are, for example, the polyhydric, in particular dihydric alcohols mentioned for the preparation of the polyol polyols, and furthermore low molecular weight polyester diols such as, for example, Adipic acid bis (hydroxyethyl) esters or short-chain homo- and mixed addition products of ethylene oxide or propylene oxide started on aromatic diols. Examples of aromatic diols which can be used as starters for short-chain homopolymers and copolymers of ethylene oxide or propylene oxide are, for. B. 1,4-, 1,3-, 1,2-dihydroxybenzene or 2,2-bis (4-hydroxyphenyl) propane (bisphenol A).

In the sense of the isocyanate polyaddition reaction, mono-functional compounds with an ethylene oxide content of at least 50% by weight and a molecular weight of at least 400 Daltons, which are suitable as structural components C) are hydrophilic structural components for the incorporation of terminal chains of the formula (I) having hydrophilic ethylene oxide units,

H-Y'-X-Y-R (I)

in which

R represents a monovalent hydrocarbon radical having 1 to 12 carbon atoms, preferably an unsubstituted alkyl radical having 1 to 4 carbon atoms,

X for a polyalkylene oxide chain with 5 to 90, preferably 20 to 70 chain links, which consist of at least 51%, preferably at least 65%, of ethylene oxide units and which, in addition to ethylene oxide units, consist of propylene oxide, butylene oxide or styrene oxide units , propylene oxide units being preferred among the latter units,

Y preferred for oxygen and

Y 'preferably represents oxygen or also -NR'-, where R' corresponds to R or hydrogen in terms of its definition.

However, monofunctional structural components C) are preferably used only in molar amounts of <10 mol%, based on the polyisocyanate used, in order to ensure the desired high molecular structure of the polyurethane or polyurethane ureas. If larger molar amounts of monofunctional alkylene oxide polyethers C) are used, it is advantageous to use trifunctional compounds which have isocyanate-reactive hydrogen atoms, but with the proviso that the average functionality of the starting compounds A) to C) is not greater than 2.7. is preferably not greater than 2.35. The monofunctional, hydrophilic structural components are prepared in analogy to the manner described in DE-A 23 14 512 or 23 14 513 or in US-A 3 905 929 or 3 920 598 by alkoxylation of a monofunctional starter such as e.g. Methanol, ethanol, i-propanol, n-butanol or N-methyl-butylamine using ethylene oxide and optionally another alkylene oxide such as e.g. Propylene oxide.

Preferred as structural components C) are the copolymers of ethylene oxide with propylene oxide with an ethylene oxide mass fraction greater than 50%, particularly preferably from 55 to 89%.

In a preferred embodiment, compounds with a molecular weight of at least 400 daltons, preferably of at least 500 daltons and particularly preferably of 1200 to 4500 daltons are used as structural components C). Suitable construction components D) are diols which additionally contain 0.5 to 2 mol, preferably 0.8 to 1 mol, of sulfonic acid or sulfonate groups per molecule. Suitable structural components D) are compounds corresponding to the general formula (IT)

in which

A and B represent equivalent or different, divalent, aliphatic hydrocarbon radicals having 1 to 12 carbon atoms,

D represents an aliphatic hydrocarbon radical with 0 to 6 carbon atoms,

X represents an alkali metal cation, a proton or NR, where R represents identical or different radicals where R = hydrogen or an aliphatic or cycloaliphatic radical with 1 to 6 carbon atoms,

n / m are the same or different natural numbers, where n + m is a number from 0 to 30,

o / p stands for 0 or 1.

If structural components D) are used as free sulfonic acids, these must be converted into their ionic form by adding suitable neutralizing agents before the polymer melt is converted into water. Suitable neutralizing agents are e.g. tertiary amines such as triethylamine, tripropylamine, diisopropylethylamine, dimethylethanolamine or triethanolamine, inorganic bases such as ammonia or sodium or potassium hydroxide, hydrogen carbonate or carbonate. The preferred counterion is the sodium ion.

Construction components D) with a number average molecular weight of 200 to 4000 daltons are preferred, preferably 300 to 2000 daltons. Structural components D) which are accessible by addition of alkali hydrogen sulfite to propoxylated 2-butenediol-1,4 with a degree of propoxylation of n + m = 4 to 8 are very particularly preferred. Any organic compounds which have at least two free isocyanate groups per molecule are suitable as structural components E). Diisocyanates Y (NCO) ₂ are preferably used, Y being a divalent aliphatic hydrocarbon radical having 4 to 12 carbon atoms, a divalent cycloaliphatic hydrocarbon radical having 6 to 15 carbon atoms, a divalent aromatic hydrocarbon radical having 6 to 15 carbon atoms or one divalent araliphatic hydrocarbon radical having 7 to 15 carbon atoms.

Examples of such preferred diisocyanates are tetramethylene diisocyanate, methylpentamethylene diisocyanate, hexamethylene diisocyanate, dodecamethylene diisocyanate, 1,4-diisocyanato-cyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane, 4,4'-diisocyanato-dicyclohexyl methane , 4,4'-diisocyanatodicyclohexylpropane- (2,2), 1,4-di-isocyanatobenzene, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4'-diisocyanatodiphenyl nylmethane, 2nd , 2'- and 2,4'-diisocyanatodiphenylmethane, tetramethylxylylene diisocyanate, p-xylylene diisocyanate, p-isopropylidene diisocyanate and mixtures consisting of these compounds.

Further examples of compounds which can be used as the diisocyanate component are e.g. B. by W. Siefken in Jusrus Liebigs Annalen der Chemie, 562, pp. 75-136.

It is of course also possible to use the higher-functionality polyisocyanates known per se in polyurethane chemistry, or else modified polyisocyanates containing, for example, carbodiimide groups, allophanate groups, isocyanurate groups, urethane groups and / or biuret groups.

In addition to these simple diisocyanates, polyisocyanates are also suitable which contain heteroatoms in the radical linking the isocyanate groups and / or have a functionality of more than 2 isocyanate groups per molecule. The former are e.g. by modification of simple aliphatic, cycloaliphatic, araliphatic and / or aromatic diisocyanates, polyisocyanates made up of at least two diisocyanates with uretdione, isocyanurate, urethane, allophanate, biuret, carbodiimide, imino-oxadiazinedione and / or oxadiazinetrione , An example of an unmodified polyisocyanate with more than 2 isocyanate groups per molecule is e.g. 4-Isocyanatomethyl-1, 8-octane diisocyanate (nonanetriisocyanate) called.

Particularly preferred diisocyanates E) are aliphatic and araliphatic diisocyanates such as hexamethylene diisocyanate, 1,4-diisocyanatocyclohexane, l-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane, 4,4'-diisocyanatodicyclohexyl methane, 4,4'-diisocyanato-dicyclohexylpropane (2,2), and mixtures consisting of these compounds. Known surfactants and emulsifiers, such as those described by K. Kosswig in K. Kosswig & H. Stache - "Die Tenside", Carl Hanser Verlag 1993, pages 115-177, are suitable as components F). Nonionic surfactants (p 147 - 161) Suitable nonionic, external emulsifiers are reaction products of aliphatic, araliphatic, cycloaliphatic or aromatic carboxylic acids, alcohols, phenol derivatives or amines with epoxides, such as ethylene oxide. Examples of this are reaction products of ethylene oxide with carboxylic acids of castor oil, abietic acid, lauric, myristic, palmitic, margarine, stearic, arachinic, behenic, lignoceric or unsaturated monocarboxylic acids such as oleic, linoleic, linolenic, ricinoleic or aromatic monocarboxylic acids such as benzoic acid, with fatty acid alkanolamides longer-chain alcohols such as oleyl alcohol, lauryl alcohol, stearyl alcohol, with phenol derivatives such as substituted benzyl, pheny Iphenols, nonylphenols, fatty acid and with longer-chain amines such as dodecylamine and stearylamine, with fatty acid glycerides or with sorbitan esters. The reaction products with ethylene oxide are oligo- or polyethers with degrees of polymerization between 2 and 100, preferably between 5 and 50. To dampen the foaming behavior, part of the ethylene oxide can also be replaced by propylene oxide. It has proven to be advantageous for minimizing foam formation to add ethylene oxide and propylene oxide in blocks. The ethoxylation products of sorbitan esters of lauric, myristic, palmitic, margarine, stearic, arachinic, behenic, lignoceric or unsaturated monocarboxylic acids such as oleic, linoleic, linolenic, ricinoleic or aromatic monocarboxylic acids such as benzoic acid are particularly preferred.

External emulsifiers which are liquid at room temperature and have an LHB value (lipophilic hydrophilic balance) of 12 to 18, preferably 15 to 18, have proven to be particularly advantageous for the purposes of this invention. Examples are emulsifier EA 9 (lauryl alcohol, mol EO 30), EA 12 (stearyl alcohol, mol EO 7), EA 17 (oleyl alcohol, mol EO 19), EPS 4 (phenol methylstyrene, mol EO 96.5), EPS 5 (phenol / Methylstyrene, mol EO 27), EPS 8 (phenol / styrene, mol EO 29), EPS 9 (phenol / styrene, mol EO 54) (Bayer AG, Leverkusen / D), Lutensol ^® XL 140 (decanol ethoxylate with approx. 14 Mol EO) or AP 20 (alkylphenol + 20 EO) (BASF AG, Ludwigshafen / D). Ethoxylation products of the fatty acid ester of sorbitol, such as, for example, are particularly preferred. Tween ^® 20, 40, 60 or 80 (Uniqema, Wesel / D) or Merpoxen ^® SML 200, SMS 200 or SMO 200 (polyoxyethylene-20-sorbitan monolaurate) (Wall Chemie GmbH; Kempen / D).

The external emulsifiers are used in amounts of 0.1 to 7.5% by weight, preferably 0.5 to 5% by weight, particularly preferably 0.5 to 3% by weight, based on the non-volatile content of the polyurethane or. Polyurethane-polyurea dispersion used. As structural components G) are aliphatic and / or alicyclic primary and / or secondary mono- and polyamines, such as ethylamine, the isomeric propylamines and butylamines, higher linear aliphatic and cycloaliphatic monoamines such as, for. B. cyclohexylamine and ethanolamine, 2-propanolamine, diethanolamine, diisopropanolamine and polyamines such as 1,2-ethanediamine, 1,6-hexamethylenediamine, l-amino-3,3,5-trimethyl-5-aminomethyl-cyclohexane ( Isophoronediamine), piperazine 1,4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, adipic acid dihydrazide or diethylene triamine.

Other polyamines include polyethene polyamines which formally come about by replacing the hydroxyl groups of the polyethene polyols described above with amino groups. Such Polyetheφolyamine can be prepared by reacting the corresponding Polyetheφolyole with ammonia and / or primary amines.

Preferred structural component G) is hydrazine or hydrazine hydrate.

It is particularly preferred to use the structural components G) as mixtures of mono- and diamines, such as. B. ethanolamine / ethylenediamine, diethanolamine / ethylenediamine, ethanolamine / l-amino-3,3,5-trimethyl-5-aminomethyl-cyclohexane or diethanolamine / l-amino-3,3,5-trimethyl-5-amino-methyl- Use cyclohexane. Mixing ratios of monoamine to diamine of 1:20 to 1: 1 are preferred, particularly preferably 1:15 to 1: 5.

The polyurethane resin dispersions according to the invention are prepared by known processes of the prior art, such as D. Dieterich in Houben-Weyl "Methods of Organic Chemistry", Volume E20, pp. 1670-81 (1987). The polyurethane dispersions according to the invention are preferably prepared in the so-called prepolymer mixing process.

In the prepolymer mixing process, the aqueous preparations of polyurethane resins on which the dispersions according to the invention are based are built up in a multi-stage process.

In a first stage, a prepolymer containing isocyanate groups is built up from build-up components A) to E). The amounts of the individual components used are dimensioned such that an isocyanate index of 1.1 to 3.5, preferably of 1.35 to 2.5, results. The isocyanate content of the prepolymers is between 1.5 and 7.5%, preferably between 2 and 4.5% and particularly preferably between 2.5 and 4.0%. When dimensioning the structural components A) to E), care must also be taken to ensure that the mathematical, number-average functionality is between 1.80 and 3.50, preferably between 1.95 and 2.25. 50 to 90 parts by weight, preferably 65 to 80 parts by weight of component A), 0 to 15 parts by weight, preferably 0 to 5 parts by weight of component B), 0.5 to 10 parts by weight . Parts, preferably 1 to 5 parts by weight of component C), 1 to 15 parts by weight, preferably 3 to 10 parts by weight of component D) and 5 to 30 parts by weight, preferably 10 to 25 Parts by weight of component E) used with the stipulation that the sum of the components is 100.

To accelerate the urethanization reaction, customary catalysts can be used, as are known to the person skilled in the art to accelerate the NCO-OH reaction. Examples are tert. Amines such as Triethylamine, diazobicyclooctane (DABCO) or organotin compounds such as Dibutyltin oxide, dimethyltin dichloride, dibutyltin dilaurate or tin bis (2-ethylhexanoate) or other organometallic compounds.

In a second stage, the isocyanate-containing prepolymer produced in the first stage is mixed with the emulsifier F) and homogenized. If necessary, free sulfonic acid groups are converted into their salt form by adding neutralizing agent. It has proven to be particularly advantageous to add the neutralizing agents dissolved in component F).

In a third stage, the prepolymer containing isocyanate and emulsifier is dispersed by addition or by introduction into water under suitable stirring conditions. The prepolymer melt is preferably introduced into water. The resulting isocyanate-containing dispersions have a solids content of 30 to 70% by weight, preferably 38 to 58% by weight.

In a fourth stage, the aqueous, isocyanate-containing dispersion is reacted with an aqueous solution of the aminoflinc ionic components G) to give the polyurethane or polyurethane-polyurea. Based on the total polymer, 0.5 to 10% by weight, preferably 1 to 7.5% by weight, of structural component G) are used. The concentration of the aqueous chain extender solution is 5 to 50% by weight, preferably 8 to 35% by weight, particularly preferably 10 to 25% by weight. The amounts of the build-up components are such that 0.3 to 0.93 mol, preferably 0.5 to 0.85 mol, of primary and / or secondary amino groups of the build-up components G) result per mole of isocyanate groups in the dispersed prepolymer. The calculated, number-average isocyanate functionality of the resulting polyurethane-polyurea resin according to the invention is between 1.5 and 3.5, preferably between 1.7 and 2.5. The calculated number average molecular weight (Mn) is between 3000 and 100000, preferably between 4500 and 25000 Daltons.

In a fifth stage, the remaining isocyanate groups are reacted by reaction with water with chain extension. The calculated, number-average hydroxyl functionality of the resulting polyurethane-polyurea resin according to the invention is between 1.5 and 5, preferably between 1.95 and 2.5. The calculated number average molecular weight (Mn) is between 10,000 and 425,000, preferably between 25,000 and 250,000 Daltons.

The present invention also relates to adhesives containing the polyurethane or polyurethane-polyurea dispersions according to the invention.

Before use, polyisocyanate compounds with at least two isocyanate groups per molecule can be added to the dispersions according to the invention (two-component processing). In this case, particular preference is given to using polyisocyanate compounds which are emulsifiable in water. These are e.g. B. the compounds described in EP-A 206 059, DE-A 31 12 117 or DE-A 100 24 624. The polyisocyanate compounds are used in an amount of 0.1 to 20% by weight, preferably 0.5 to 10% by weight, particularly preferably 1.5 to 6% by weight, based on the aqueous preparation.

The adhesives are suitable for bonding any substrates such as. B. paper, cardboard, wood, textiles, metal, leather or mineral materials. The adhesives according to the invention are particularly suitable for gluing rubber materials such. B. natural and synthetic rubber, various plastics such as polyurethanes, polyvinyl acetate, polyvinyl chloride, especially plasticized polyvinyl chloride. The use for gluing soles made of these materials, in particular based on polyvinyl chloride, in particular plasticized polyvinyl chloride or of polyethylene vinyl acetate or polyurethane elastomer foam with shoe uppers made of leather or synthetic leather, is particularly preferred. Furthermore, the adhesives according to the invention are particularly suitable for bonding films based on polyvinyl chloride or plasticized polyvinyl chloride to wood.

The adhesives according to the invention are processed according to the known methods of adhesive technology with regard to the processing of aqueous dispersion adhesives.

Examples

Starting Materials:

Polyester I: 1,4-butanediol polyadipate diol of OH-Z = 50

Polyester Et: polyester diol from 1,6-hexanediol, neopentyl glycol and adipic acid of OH-Z = 66

Polyether I: polypropylene glycol of OH-Z = 56 (Desmophen ^® 3600, Bayer AG, Leverkusen / D)

Polyether II: n-butanol-started ethylene oxide-propylene oxide copolymer with an ethylene oxide content of 78% of OH-Z = 25

Polyether DI: butanediol-1, 4-started polypropylene glycol with lateral sodium sulfonate group of OHZ = 260

Desmodur H: hexamethylene diisocyanate 1,6 (Bayer AG, Leverkusen / D))

Desmodur I: isophorone diisocyanate (Bayer AG, Leverkusen / D)

Desmodur DA: hydrophilic, aliphatic polyisocyanate based on hexamethylene diisocyanate

Emulsifier: Tween ^® 20: Sorbitan-started polyethylene oxide ether (Uniqema, Emmerich / D)

Example 1

675 g of polyester I, 64.5 g of polyether oil and 20.3 g of polyether D are dewatered at 110 ° C. and 15 mbar for 1 hour. 45.4 g Desmodur ^® H and then 119.9 g Desmodur ^® I are added at 70 ° C. The mixture is stirred at 80 to 90 ° C until a constant isocyanate content of 3.18% is reached. After addition of 18.5 g of Tween ^® 20, the mixture is introduced under vigorous stirring in 840 g of water at 40 ° C. The resulting dispersion is stirred for 15 minutes and then chain extended by adding a mixture of 12.6 g of ethylenediamine and 1.2 g of diethanolamine in 100 g of water.

The result is a solvent-free, aqueous polyurethane-polyurea dispersion with a solids content of 49.6% by weight and an average particle size of the disperse phase, determined by laser correlation, of 210 nm. Example 2

607.5 g of polyester I, 102.0 g of polyester π, 51.6 g of polyether ITJ and 20.3 g of polyether D are dewatered for 1 hour at 110 ° C. and 15 mbar. 45.6 g Desmodur ^® H and then 121.1 g Desmodur ^® I are added at 70 ° C. The mixture is stirred at 80 to 90 ° C until a constant isocyanate content of 3.16% is reached. After addition of 19.0 g of Tween ^® 20, the mixture is introduced under vigorous stirring in 855 g of water at 40 ° C. The resulting dispersion is stirred for 15 minutes and then chain extended by adding a mixture of 12.6 g of ethylenediamine and 1.9 g of diethanolamine in 105 g of water.

The result is a solvent-free, aqueous polyurethane-polyurea dispersion with a solids content of 50.0% by weight and an average particle size of the disperse phase, determined by laser correlation, of 228 nm.

Example 3

540.0 g of polyester I, 120.0 g of polyether I, 65.1 g of polyether ffl and 20.3 g of polyether π are dewatered at 110 ° C. and 15 mbar for 1 hour. 45.4 g Desmodur ^® H and then 119.9 g Desmodur ^® I are added at 70 ° C. The mixture is stirred at 80 to 90 ° C until a constant isocyanate content of 3.19% is reached. After addition of 18.2 g of Tween ^® 20, the mixture is introduced under vigorous stirring in 820 g of water at 40 ° C. The resulting dispersion is stirred for 15 minutes and then chain extended by adding a mixture of 12.5 g of ethylenediamine and 2.0 g of diethanolamine in 105 g of water.

The result is a solvent-free, aqueous polyurethane-polyurea dispersion with a solids content of 49.3% by weight and an average particle size of the disperse phase, determined by laser correlation, of 145 nm.

Example 4 Comparison According to EP 304 718 (Example 1)

360 g of polyester I is dewatered for 1 hour at 110 ° C. and 15 mbar. 23.4 g Desmodur ^® H and then 15.3 g Desmodur ^® I are added at 80 ° C. The mixture is stirred at 80 to 90 ° C until a constant isocyanate content of 0.95% is reached. The reaction mixture is dissolved in 800 g of acetone and cooled to 50 ° C. A solution of 5.8 g of sodium salt of N- (2-aminoethyl) -2-aminoethanesulfonic acid and 2.1 g of diethanolamine in 55 g of water is added to the homogeneous solution with vigorous stirring. After 7 minutes, the mixture is dispersed by adding 565 g of water. After removal of the acetone by distillation, a solvent-free, aqueous polyurethane-polyurea dispersion with a solids content of 40.1 % By weight and an average particle size of the disperse phase, determined by laser correlation, of 115 nm.

example

A) Determination of the initial heat resistance

Test material / test specimen

a) Renolit film (32052096 Strukton; Rhenolit AG, Worms / D) Dimensions: 50 x 300 x 0.4 mm

b) Beech wood (planed) Dimensions: 50 x 140 x 4.0 mm

Gluing and measurement

The adhesive dispersion is applied to the wood test specimen using a 200 μm doctor blade. The adhesive surface is 50 x 110 mm. The drying time of the applied adhesive is at least 3 hours at room temperature. The two test specimens are then placed on top of each other and joined for 10 s at 4 bar pressure at 77 ° C. Immediately afterwards the test specimen is annealed without weight for 3 min at 80 ° C, then for 5 min at 80 ° C with 2.5 kg perpendicular to the adhesive joint (180 ° peel). The distance that the bond has loosened is measured in millimeters. The initial heat resistance is given in mm / min.

B) Determination of the heat level

lK adhesive: adhesive without crosslinker

2-component adhesive: adhesive with an emulsifiable crosslinker isocyanate

3 parts Desmodur ^® DA per 100 parts adhesive are homogenized intensively.

Recommended weight: 25 g adhesive and 0.75 g crosslinker Test material / test specimen

a) Hard PVC laminating film (Benelit film, Benecke-Kaliko AG, Hanover / D)

Dimensions: 50 x 210 x 0.4 mm

b) beech wood (planed)

Dimensions: 50 x 140 x 4.0 mm

Gluing and measurement

The adhesive dispersion (1K) or the mixture of adhesive dispersion and crosslinker isocyanate (2K) is applied to the beech wood test specimen using a brush. The adhesive surface is 50 x 110 mm. After a drying time of 30 minutes at room temperature, a second layer of adhesive is applied over the first and then dried for 60 minutes at room temperature. The two test specimens are then placed on top of each other and joined for 10 s at 4 bar pressure and 90 ° C.

After the test specimens had been stored for three days at room temperature, the test specimens are loaded with 0.5 kg at an angle of 180 ° to the adhesive joint. Starting temperature is 50 ° C, after 60 min the temperature is increased by 10 ° C per hour up to a maximum of 120 ° C. The temperature at which an adhesive bond separates completely is measured in each case.

Table 1:

Claims

claims

1. Aqueous polyurethane or polyurethane-polyurea dispersions which have both ionic or potentially ionic groups and nonionic groups, the ionic groups via a difunctional polyol component which additionally contains 0.5 to 2 mol of sulfonic acid or sulfonate groups per molecule , and the nonionic groups are introduced into the polymer structure via one or more mono-functional compounds in the sense of the isocyanate polyaddition reaction having an ethylene oxide content of at least 50% by weight and a molecular weight of at least 400 Daltons, and the dispersion 0.1 to 7.5 % By weight of an emulsifier not chemically bound to the polymer.

2. A method for producing the aqueous polyurethane or polyurethane-polyurea dispersions according to claim 1, characterized in that

A) di- or higher-functional polyols with a molecular weight of 400 to 5000 daltons, B) optionally di- or higher-functional polyol components with a molecular weight of 62 to 399 daltons,

C) one or more mono-functional compounds in the sense of the isocyanate polyaddition reaction with an ethylene oxide content of at least 50% by weight and a molecular weight of at least 400 daltons and D) one or more difunctional polyol components which additionally contain 0.5 to 2 mol of sulfonic acid or Contains sulfonate groups per molecule

E) one or more di- or polyisocyanate components are converted to an isocyanate-functional prepolymer and then

F) 0.1 to 7.5% by weight of an emulsifier which has no groups reactive toward isocyanate groups and, if appropriate, a neutralizing agent for converting free acid groups from structural component D) into their ionic form, the isocyanate-containing melt with water dispersed and the chain extension by adding an aqueous solution of G) amino blinking components with a functionality of 1 to 3.

3. Adhesives containing the polyurethane or polyurethane-Po lyurea dispersions according to claim 1.

4. Use of the polyurethane or polyurethane-polyurea dispersions according to claim 1 as adhesives.

5. Use of the polyurethane or polyurethane-polyurea dispersions according to claim 1 for gluing rubber or plastic materials.

6. Use according to claim 5, characterized in that the plastic materials are selected from the group of polyurethanes, polyvinyl acetates or polyvinyl chloride.

7. Use according to claim 5, characterized in that the materials are soles and these are glued to shoe uppers made of leather or synthetic leather.

8. Use of the polyurethane or polyurethane-Po urea dispersions according to claim 1 for bonding films based on polyvinyl chloride or plasticized polyvinyl chloride and wood.