EP1937740A1 - Reactive polyurethane-hot melt adhesive having a low isocyanate-monomer content - Google Patents

Abstract

A composition contains (A) a polyurethane produced from a polyisocyanate and a polyol; and (B) an aldimine group-containing compound. A composition contains (A) a polyurethane produced from a polyisocyanate and a polyol; and (B) an aldimine group-containing compound of formula (I). m : integer 1-4; p : integer 1-6; q : integer 0-5 with the proviso that p + q= 2-6; R 1>6-30C hydrocarbyl optionally with a heteroatom, especially an oxygen ether, or is a group of formula (II); R 6>2-20C hydrocarbylene optionally with a heteroatom, especially an oxygen ether; R 7>1-20C hydrocarbyl; R 2> and R 3>1-12C hydrocarbyl or together form a 4-20C hydrocarbylene which is part of an optionally substituted 5-8 (especially 6)C carbocyclic ring; R 4>an (m + 1)-valent 2-12C hydrocarbon group optionally with a heteroatom, especially an oxygen ether, or a tert. amine nitrogen; R 5>a (p + q)-valent organic optionally heteroatom-containing group such as obtained by removal of (p + q) NCO groups from R 5>[NCO] p+q or is N, NR 14>, O, OC(O)O, Si, P(O)O 3 or SO 2; R 14>1-20C hydrocarbyl; X : O, S or NR 8>; and R 8>1-20C hydrocarbyl optionally with at least one carboxylic acid ester, nitrile, nitro, phosphonic acid ester, sulfo or sulfonic acid ester group or is a group of formula (III). [Image] [Image] [Image].

Description

REACTIVE POLYURETHANE HOT GLUE ADHESIVES WITH

LOW ISOCYANATE MONOMER CONTENT

Technical field The invention relates to the field of moisture-curing

Hot melt adhesives.

State of the art

Hotmelt adhesives (hotmelts) are adhesives based on thermoplastic polymers. These polymers are solid at room temperature, soften when heated to viscous liquids and can thus be applied as a melt. In contrast to the so-called hot melt adhesives (hot melts), which have a pasty consistency and at slightly elevated temperatures, typically in the range of 40 to 80 ⁰ C, are applied, the hot melt adhesives are applied at temperatures above 85 ⁰ C. When cooled to room temperature they solidify while simultaneously developing the adhesive strength. Classic hotmelt adhesives are non-reactive adhesives. When heated, they soften or melt again, making them unsuitable for use at elevated temperature. In addition, conventional hotmelt adhesives often tend to creep (cold flow) even at temperatures far below the softening point.

These disadvantages were largely eliminated in the case of the so-called reactive hotmelt adhesives by the introduction of reactive, crosslinking groups into the polymer structure. In particular, reactive polyurethane compositions are suitable as hot-melt adhesives. They are also called PUR-RHM for short. They usually consist of isocyanate group-containing polyurethane polymers which are obtained by reacting suitable polyols with an excess of diisocyanates. After application, they quickly build up a high adhesive strength by cooling and obtain their final properties, in particular their heat resistance and resistance to environmental influences, by the postcrosslinking of the polyurethane polymer as a result of reaction of the Isocyanate groups with moisture. However, due to the molecular weight distribution resulting from the preparation of the isocyanate-containing polyurethane polymers such PUR-RHM usually contain significant amounts of unreacted monomeric diisocyanates, which in the customary in hot-melt adhesives application temperatures of 85 ⁰ C to 200 ⁰ C, typically 120 ⁰ C to 160 ⁰ C, partial outgassing and can represent a health burden for the processor as irritating, sensitizing or toxic substances. For this reason, various efforts have been made to reduce the content of monomeric diisocyanates in reactive polyurethane compositions in general and in PUR-RHM in particular.

An obvious approach is the physical removal of the monomeric diisocyanate by distillation or extraction. These methods are complex in terms of apparatus and therefore expensive; Moreover, they are not well applicable for all diisocyanates.

Another approach is the use of specific diisocyanates having different reactive isocyanate groups. For example, WO 03/033562 A1 describes the use of an unsymmetrical MDI isomer, 2,4'-diphenylmethane diisocyanate, with which polyurethane polymers with a low content of monomeric diisocyanates can be obtained at low viscosity in a simple manner. A disadvantage of this method is the insufficient availability of suitable diisocyanates on an industrial scale, associated with a high price. In addition, losses in the rate of crosslinking are to be accepted, since only the isocyanate groups with the lower reactivity are available for the main crosslinking reaction.

Finally, one approach is to use in the reaction with polyols instead of the monomeric diisocyanates adducts or oligomers thereof to reduce the volatility, described for example in DE 44 29 679 A1. This results in disadvantages in the viscosity and the reactivity of the products thus produced. Presentation of the invention

It is therefore an object of the present invention to provide polyurethane compositions (PUR-RHM) which can be used as hot-melt adhesive and which are obtainable in a simple process starting from polyols and industrially available monomeric diisocyanates and which have a low content have monomeric diisocyanates, are stable on storage and easy to process, and which have a rapid crosslinking.

Surprisingly, it has been found that the object can be achieved with compositions according to claim 1. These contain at room temperature solid, aldimine-containing polyurethane polymers, which can be prepared by reacting corresponding isocyanate-containing polyurethane polymers with specific compounds containing one or more aldimine and an active hydrogen.

Another aspect of the invention relates to a cured composition according to claim 14, as well as the use of the composition as a hot-melt adhesive and a method for bonding and resulting from such a process article. Finally, in another aspect, the invention relates to a

Process for reducing the content of monomeric diisocyanates in polyurethane polymers containing isocyanate groups or in compositions containing polyurethane polymers containing isocyanate groups by reacting the isocyanate group-containing polyurethane polymers with specific compounds containing one or more aldimine groups and one active hydrogen. Ways to carry out the invention

The invention relates to compositions comprising a) at least one room temperature solid, aldimine-containing polyurethane polymer of the formula (I),

where in formula (I) p is an integer of 1 or 2, preferably 1, q is an integer of 0 or 1, preferably 1, with the proviso that p + q = 2;

R ^{1 is} either a monovalent hydrocarbon radical having 6 to 30 carbon atoms, which optionally has at least one heteroatom, in particular in the form of ether oxygen; or R ^{1 is} a substituent of the formula (II),

where R ^{6 is} a divalent hydrocarbon radical having 2 to 20 C atoms, which optionally has at least one hetero atom, in particular in the form of ether oxygen, and R ^{7 is} a monovalent hydrocarbon radical having 1 to 20 C atoms ;

R ² and R ^{3 are} either two independent substituents, each representing a monovalent hydrocarbon radical having 1 to 12 C atoms, or R ² and R ³ together form a single substituent containing a bivalent hydrocarbon radical having 4 to 20 C atoms which is part of a carbocyclic ring having 5 to 8, preferably 6, carbon atoms, which carbocyclic ring may be substituted; R ^{4 is} a divalent hydrocarbon radical having 2 to 12 C atoms, which optionally has at least one heteroatom, in particular in the form of ether oxygen or tertiary amine nitrogen; R ^{5 is} the residue of a room temperature solid, isocyanate group-containing polyurethane polymer after removal of (p + q) isocyanate groups; and

X is O, S or NR ⁸ , wherein R ^{8 is} either a monovalent hydrocarbon radical having 1 to 20 C atoms, which optionally has at least one carboxylic acid ester, nitrile, nitro, phosphonic ester, sulfonic or sulfonic acid ester group, or R ^{8 represents} a substituent of the formula (III) with the meanings already mentioned for R ¹ , R ² , R ³ and R ⁴

b) at least one isocyanate group-containing polyurethane polymer P, if q in formula (I) is zero, or if X in formula (I) is NR ⁸ with R ⁸ as a substituent of formula (III).

The dashed lines in the formulas in this document each represent the bond between a substituent and the associated moiety.

In a particularly preferred embodiment, R ² = R ³ = methyl, and R ¹ is a hydrocarbon radical having 11 to 30 C atoms.

These compositions are useful as reactive hot melt adhesive compositions, also referred to as "PUR-RHM" for short.

The term "polymer" in the present document comprises, on the one hand, a collective of chemically uniform, but with respect to degree of polymerization, molecular weight and chain length, different macromolecules. which was produced by a polyreaction (polymerization, polyaddition, polycondensation). On the other hand, the term also encompasses derivatives of such a collective of macromolecules from polyreactions, compounds which have been obtained by reactions, such as additions or substitutions, of functional groups on given macromolecules and which may be chemically uniform or chemically nonuniform. The term also includes so-called prepolymers, ie reactive oligomeric pre-adducts whose functional groups are involved in the construction of macromolecules. The term "polyurethane polymer" encompasses all polymers which are prepared by the so-called diisocyanate-polyaddition process, including those polymers which are almost or completely free of urethane groups Examples of polyurethane polymers are polyether polyurethanes, polyester polyurethanes, polyethers Polyureas, polyureas, polyester-polyureas, polyisocyanurates, and polycarbodiimides. "Room temperature" refers to a temperature of 25 ^° C.

The room temperature solid aldimine group-containing polyurethane polymer of the formula (I) can be prepared by the reaction of at least one aldimine of the formula (XI) containing an active hydrogen with at least one isocyanate group-containing polyurethane polymer D. The active hydrogen-bearing reactive group of the aldimine of the formula ( XI) reacts in an addition reaction with an isocyanate group of the polyurethane polymer D. The term "active hydrogen" in the present document refers to a deprotonatable hydrogen atom bound to a nitrogen, oxygen or sulfur atom The term "reactive group containing an active hydrogen" denotes a an active hydrogen-containing functional group, in particular a primary or secondary amino group, a hydroxyl group, a mercapto group or a urea group.

In the formula (XI), R ¹ , R ² , R ³ , R ⁴ and X have the same meaning as described for the formula (I).

The aldimine of the formula (XI) can be prepared from at least one sterically hindered aliphatic aldehyde A and at least one aliphatic amine B corresponding to the formula H ₂ NR ⁴ -XH which, in addition to one or more primary amino groups, also contains another reactive group containing an active hydrogen having.

The reaction between the aldehyde A and the amine B takes place in a condensation reaction with elimination of water. Such condensation reactions are well known and described, for example, in Houben-Weyl, "Methods of Organic Chemistry", Vol. XI / 2, page 73 et seq .. The aldehyde A is used here with respect to the primary amino groups of the amine B stoichiometrically or in stoichiometric excess For the preparation of the aldimine of the formula (XI), at least one sterically hindered aliphatic aldehyde A of the formula (IV) is used,

In formula (IV), R ¹ , R ² and R ^{3 have} the same meaning as described for formula (I).

The aldehyde A is odorless. By an "odorless" substance is meant a substance that is so low in odor that it is not palpable to most human individuals, that is imperceptible to the nose.

The aldehyde A is prepared, for example, from a carboxylic acid

R ¹ -COOH and a ß-hydroxyaldehyde of the formula (V) in an esterification reaction. This esterification can be carried out by known methods, for example, in Houben-Weyl, "Methoden der organischen Chemie", Vol. VIII, pages 516-528 The β-hydroxyaldehyde of the formula (V) is used, for example, in a crossed aldol addition from formaldehyde or oligomeric forms of formaldehyde, such as Paraformaldehyde or 1,3,5-trioxane - and an aldehyde of formula (VI).

In formulas (V) and (VI), R ² and R ^{3 have} the same meaning as described for formula (I).

Examples of suitable carboxylic acids R ¹ -COOH for esterification with the .beta.-hydroxyaldehydes of the formula (V) are: saturated aliphatic carboxylic acids such as enanthic acid, caprylic acid, pelargonic acid, capric acid, undecanoic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, margarinic acid , Stearic acid, nonadecanoic acid, arachidic acid; monounsaturated aliphatic carboxylic acids such as palmitoleic acid, oleic acid, erucic acid; polyunsaturated aliphatic carboxylic acids such as linoleic acid, linolenic acid, elaeostearic acid, arachidonic acid; cycloaliphatic carboxylic acids such as cyclohexane carboxylic acid; arylaliphatic carboxylic acids such as phenylacetic acid; aromatic carboxylic acids such as benzoic acid, naphthoic acid, toluic acid, anisic acid; Isomers of these acids; Fatty acid mixtures from the industrial saponification of natural oils and fats such as rapeseed oil, sunflower oil, linseed oil, olive oil, coconut oil, oil of palm kernel oil and oil palm oil; and dicarboxylic monoalkyl and aryl esters, such as those obtained from the simple esterification of dicarboxylic acids such as succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, 1,12-dodecanedioic acid, maleic acid, fumaric acid, hexahydrophthalic acid, hexahydroisophthalic acid, hexahydroterephthalic acid, 3,6,9-trioxaundecanedioic acid and similar derivatives of Polyethylene glycol, with alcohols such as methanol, ethanol, propanol, butanol, higher homologues and isomers of these alcohols can be obtained.

Preference is given to caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, the isomers of these acids and technical mixtures of fatty acids which contain these acids. Particularly preferred is lauric acid.

Suitable aldehydes of the formula (VI) for reacting with formaldehyde to give β-hydroxyaldehydes of the formula (V) are, for example, isobutyraldehyde, 2-methylbutyraldehyde, 2-ethylbutyraldehyde, 2-methylvaleraldehyde, 2-ethylcapronaldehyde, cyclopentanecarboxaldehyde, cyclohexanecarboxaldehyde, 1, 2, 3,6-tetrahydrobenzaldehyde, 2-methyl-3-phenylpropionaldehyde, 2-phenylpropionaldehyde and diphenylacetaldehyde. Isobutyraldehyde is preferred.

Suitable β-hydroxyaldehydes of the formula (V) are, for example, the products of the reaction of formaldehyde with the aldehydes of the formula (VI) mentioned above as suitable. Preference is given to 3-hydroxypivalaldehyde.

The amine B is an aliphatic amine which, in addition to one or more primary amino groups, also has another reactive group which contains an active hydrogen. The term "primary amino group" in the present document denotes an NH ₂ group which is bonded to an organic radical, while the term "secondary amino group" denotes an NH group which is bonded to two organic radicals. The term "aliphatic amine" refers to compounds which contain at least one amino group attached to an aliphatic, cycloaliphatic or arylaliphatic radical and differ from aromatic amines in which the amino group is attached directly to an aromatic radical such as, for example in aniline or 2-aminopyridine.

Suitable amines B are, for example, the following compounds: aliphatic hydroxyamines such as 2-aminoethanol, 2-methylaminoethanol, 1-amino-2-propanol, 3-amino-1-propanol, 4-amino-1-butanol, 4-amino-2-butanol, 2-amino-2-methylpropanol, 5-amino-1-pentanol, 6-amino-1-hexanol, 7-amino-1-heptanol, 8-amino-1-octanol, 10 Amino-1-decanol, 12-amino-1-dodecanol decanol, 4- (2-aminoethyl) -2-hydroxyethylbenzene, 3-aminomethyl-3,5,5-trimethylcyclohexanol; a primary amino-bearing derivatives of glycols such as diethylene glycol, dipropylene glycol, dibutylene glycol and higher oligomers and polymers of these glycols, for example 2- (2-aminoethoxy) - ethanol, triethylene glycol monoamine, α- (2-hydroxymethylethyl) -ω- (2-amino - methylethoxy) -poly (oxy (methyl-1,2-ethanediyl)); a hydroxyl group and an amino group-bearing derivatives of polyalkoxylated trihydric or higher alcohols or polyalkoxylated diamines; Products of simple cyanoethylation and subsequent hydrogenation of glycols, for example 3- (2-hydroxyethoxy) propylamine, 3- (2- (2-hydroxyethoxy) ethoxy) propylamine, 3- (6-hydroxyhexyloxy) propylamine;

aliphatic mercaptoamines such as 2-aminoethanethiol (cysteamine), 3-aminopropanethiol, 4-amino-1-butanethiol, 6-amino-1-hexanethiol, 8-amino-1-octanethiol, 10-amino-1-decanethiol, 12-amino -1-dodecanethiol; Aminothio sugars such as 2-amino-2-deoxy-6-thioglucose;

- di- or polyhydric aliphatic amines which carry a secondary amino group in addition to one or two primary amino groups, such as N-methyl-1, 2-ethanediamine, N-ethyl-1, 2-ethanediamine, N-butyl-1, 2-ethanediamine , N-hexyl-1,2-ethanediamine, N- (2-ethylhexyl) -1, 2-ethanediamine, N-cyclohexyl-1,2-ethanediamine, 4-aminomethylpiperidine, 3- (4-aminobutyl) piperidine , N-aminoethylpiperazine, diethylenetriamine (DETA), bis-hexamethylenetriamine (BHMT); Di- and triamines from the cyanoethylation or cyanobutylation of primary mono- and diamines, for example N-methyl-1,3-propanediamine, N-ethyl-1,3-propanediamine, N-butyl-1,3-propanediamine, N-hexyl -1, 3-propanediamine, N- (2-ethylhexyl) -1, 3-propanediamine, N-dodecyl-1,3-propanediamine, N-cyclohexyl-1,3-propanediamine, 3-methylamino-1-pentylamine, 3 Ethylamino-1-pentylamine, 3-butylamino-1-pentylamine, 3-hexylamino-1-pentylamine, 3- (2-ethylhexyl) amino-1-pentylamine, 3-dodecylamino-1-pentylamine, 3-cyclohexylamino-1 - pentylamine, dipropylenetriamine (DPTA), N3- (3-aminopentyl) -1,3-pentanediamine, N5- (3-aminopropyl) -2-methyl-1, 5-pentanediamine, N5- (3-amino-1 - ethyl-propyl) -2-methyl-1,5-pentanediamine, and fatty diamines such as N-cocoalkyl-1,3-propanediamine, N-oleyl-1,3-propanediamine, N-soyaalkyl-1,3-propanediamine, N-tallowalkylamine. 1, 3-propanediamine or N- (C _6-22 alkyl) -1, 3-propanediamine, as are obtainable for example under the trade name Duomeen ^® ex Akzo Nobel; the products of the Michael-type addition of aliphatic primary di- or polyamines with acrylonitrile, maleic or fumaric diesters, citraconic diesters, acrylic and methacrylic acid esters and itaconic diesters, reacted in a molar ratio of 1: 1; trisubstituted ureas bearing one or more primary amino groups, such as N- (2-aminoethyl) ethyleneurea, N- (2-aminoethyl) propyleneurea or N- (2-aminoethyl) -N'-methylurea.

Particularly suitable aliphatic hydroxy and mercaptoamines are those in which the primary amino group of the hydroxyl or the mercapto group are separated by a chain of at least 5 atoms, or by a ring, such as in 5-amino-1-pentanol, 6 Amino-1-hexanol, 7-amino-1-heptanol, 8-amino-1-octanol, 10-amino-1-decanol, 12-amino-1-dodecanol, 4- (2-aminoethyl) -2 -hydroxyethylbenzene, 3-amino-methyl-3,5,5-trimethyl-cyclohexanol, 2- (2-aminoethoxy) -ethanol, triethylene glycol monoamine, α- (2-hydroxymethylethyl) -ω- (2-aminomethylethoxy) poly (oxy (methyl-1,2-ethanediyl)), 3- (2-hydroxyethoxy) propylamine, 3- (2- (2-hydroxyethoxy) ethoxy) propylamine, 3- (6-hydroxyhexyloxy ) -propylamine, 6-amino-1-hexanethiol, 8-amino-1-octanethiol, 10-amino-1-decanethiol and 12-amino-1-decanethiol.

Preferred amines B are di- or polyhydric aliphatic amines which, in addition to one or two primary amino groups, carry a secondary amino group, in particular N-methyl-1,2-ethanediamine, N-ethyl-1,2-ethanediamine, N-cyclohexyl-1 , 2-ethanediamine, N-methyl-1,3-propanediamine, N-ethyl-1,3-propanediamine, N-butyl-1,3-propanediamine, N-cyclohexyl-1,3-propanediamine, 4-aminomethyl -piperidine, 3- (4-aminobutyl) piperidine, DETA, DPTA, BHMT and fatty diamines such as N-cocoalkyl-1,3-propanediamine, N-oleyl-1,3-propanediamine, N-soyalkyl-1,3 propanediamine and N-tallow alkyl-1,3-propanediamine. Also preferred are aliphatic hydroxy and mercaptoamines in which the primary amino group of the hydroxyl or the mercapto group are separated by a chain of at least 5 atoms, or by a ring, in particular 5-amino-1-pentanol, 6-amino 1-hexanol and higher homo- of these, 4- (2-aminoethyl) -2-hydroxyethylbenzene, 3-aminomethyl-3,5,5-trimethyl-cyclohexanol, 2- (2-aminoethoxy) ethanol, triethylene glycol monoamine and higher oligomers and polymers thereof, 3- (2-hydroxyethoxy) -propylamine, 3- (2- (2-hydroxyethoxy) -ethoxy) -propylamine, and 3- (6-hydroxyhexyloxy) -propylamine.

The reaction between an aldehyde A and an amine B leads to hydroxyaldimines when amine B is a hydroxyamine; to mercaptoaldimines, when a mercaptoamine is used as amine B; to aminoaldimines, when as amine B, a di- or polyvalent amine, which in addition to one or more primary amino groups carries a secondary amino groups, is used; or to urea-aldimines when amine B is a trisubstituted urea bearing one or more primary amino groups.

Preferred amine B are hydroxyamines and amines having one or two primary amino groups and one secondary amino group.

In one embodiment, the aldimines of the formula (XI) have a substituent NR ⁸ as substituent X. Such aldimines of the formula (XI) can be prepared by reacting at least one sterically hindered aliphatic aldehyde A of the formula (IV) with a divalent aliphatic primary amine C of the formula H ₂ NR ⁴ -NH ₂ in a first step to form an intermediate of the formula (VII) is reacted, which in addition to an aldimine group still contains a primary amino group, and this intermediate subsequently in a second step in an addition reaction with a Michael acceptor of the formula (VIII) in a ratio of the number of double bonds: number of NH ₂ groups 1: 1 is implemented. This results in an aminoaldimine which, in addition to an aldimine group, also contains a secondary amino group.

In formula (VII), R ¹ , R ² , R ³ and R ^{4 have} the same meaning as described for formula (I).

Thus, aldimines of the formula (XI) in which X is the radical NR ⁸ and R ^{8 is} a monovalent hydrocarbon radical of the formula (IX) or (IX ') are formed. In the formulas (VIII), (IX) and (IX ') here R ^{9 is} a radical which is selected from the group consisting of -COOR ¹³ , -CN, -NO ₂ , -PO (OR ¹³ ) ₂ , -SO ₂ R ¹³ and -SO ₂ OR ¹³ and R ^{10 represent} a hydrogen atom or a radical selected from the group consisting of -R ¹³ , -COOR ¹³ and -CH ₂ COOR ¹³ and R ¹¹ and R ¹² independently represent a hydrogen atom or a radical from the group consisting of -R ¹³ , -COOR ¹³ and -CN, where R ^{13 is in} each case a monovalent hydrocarbon radical having 1 to 20 C atoms.

The amine C is an aliphatic amine having two primary amino groups.

Examples of suitable amines C are aliphatic diamines such as ethylenediamine, 1,2- and 1,3-propanediamine, 2-methyl-1,2-propanediamine, 2,2-dimethyl-1,3-propanediamine, 1, 3 and 1,4-butanediamine, 1, 3- and 1,5-pentanediamine, 2-butyl-2-ethyl-1, 5-pentanediamine, 1,6-hexamethylenediamine (HMDA), 2,2,4- and 2, 4,4-trimethylhexamethylenediamine and mixtures thereof (TMD), 1, 7-heptanediamine, 1,8-octanediamine, 2,4-dimethyl-1,8-octanediamine, 4-aminomethyl-1,8-octanediamine, 1, 9- Nonanediamine, 2-methyl-1, 9-nonanediamine, 5-methyl-1, 9-nonanediamine, 1, 10-decanediamine, isodecanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, methyl bis (3-aminopropyl ) amine, 1, 5-diamino-2-methylpentane (MPMD), 1, 3-diaminopentane (DAMP), 2,5-dimethyl-1,6-hexamethylenediamine; cycloaliphatic diamines such as 1, 2, 1, 3 and 1, 4-diaminocyclohexane, bis (4-aminocyclohexyl) -methane (Hi ₂ MDA), bis (4-amino-3-methylcyclohexyl) -methane, bis- (4-amino-3-ethylcyclohexyl) methane, bis (4-amino-3,5-dimethylcyclohexyl) methane, bis (4-amino-3-ethyl-5-methylcyclohexyl) methane (M-MECA ), 1-amino 3-aminomethyl-3,5,5-trimethylcyclohexane (= isophoronediamine or IPDA), 2- and 4-methyl-1,3-diaminocyclohexane, and mixtures thereof, 1,3- and 1,4-bis (aminomethyl) cyclohexane, 1-Cyclohexylamino-3-aminopropane, 2,5 (2,6) -bis (aminomethyl) bicyclo [2.2.1] heptane (NBDA, manufactured by Mitsui Chemicals), 3 (4), 8 (9) -bis (aminomethyl) -tricyclo [5.2.1.0 ^{2 6} ] decane, 1,4-diamino-2,2,6-trimethylcyclohexane (TMCDA), 3,9-bis (3-aminopropyl) -2,4, 8, 10-tetraoxaspiro [5.5] undecane; arylaliphatic diamines such as 1,3-xylylenediamine (MXDA), 1,4-xylylenediamine (PXDA), ether-group-containing aliphatic diamines such as bis (2-aminoethyl) ether, 4,7-dioxadecane-1,10-diamine, 4, 9-dioxadodecane-1, 12-diamine and higher oligomers thereof; Polyoxyalkylenediamines, for example, available under the name Jeffamine ^® (produced by Huntsman Chemicals). Preferred are diamines in which the primary amino groups are separated by a chain of at least 5 atoms, or by a ring, in particular 1, 5-diamino-2-methylpentane, 1, 6-hexamethylenediamine, 2,2,4- and 2 , 4,4-trimethylhexamethylenediamine and mixtures thereof, 1, 10-decanediamine, 1, 12-dodecanediamine, 1, 3 and 1, 4-diaminocyclohexane, bis (4-aminocyclohexyl) methane, bis (4- amino-3-methylcyclohexyl) methane, 1-amino-3-aminomethyl-3,5,5-thmethylcyclohexane, 1, 3, and 1, 4-bis (aminomethyl) cyclohexane, 2.5 (2.6) - Bis- (aminomethyl) -bicyclo [2.2.1] heptane, 3 (4), 8 (9) -bis (aminomethyl) -tricyclo [5.2.1.0 ² ' ⁶ ] decane, 1, 4-diamino-2, 2,6-trimethylcyclohexane (TMCDA), 3,9-bis (3-aminopropyl) -2,4,8,10-tetraoxaspiro [5.5] undecane, 1, 3- and 1, 4-xylylenediamine, as well as polyoxyalkylene diamines , for example, available under the name Jeffamine ^® (produced by Huntsman Chemicals).

Examples of suitable Michael acceptors of the formula (VIII) are maleic or fumaric diesters, such as dimethyl maleate, diethyl maleate, dibutyl maleate, diethyl fumarate; Citraconic diesters such as dimethyl citraconate; Acrylic or methacrylic acid esters such as methyl (meth) acrylate, ethyl (meth) acrylate, butyl (meth) acrylate, l-auryl (meth) acrylate, stearyl (meth) acrylate, tetrahydrofuryl (meth) acrylate, isobornyl (meth) acrylate; Itaconic diesters such as dimethyl itaconate; Cinnamic acid esters such as methyl cinnamate; Vinylphosphonsäurediester such as dimethyl vinylphosphonate; Vinylsulfonic acid esters, in particular vinylsulfonic acid aryl esters; vinyl sulfones; Vinylnitriles such as acrylonitrile, 2-pentenenitrile or fumaronitrile; 1-nitroethylenes such as β-nitrostyrene; and Knoevenagel condensation products such as those from malonic diesters and aldehydes such as formaldehyde, acetaldehyde or benzaldehyde. Preference is given to maleic acid diesters, acrylic esters, phosphonic diesters and vinylnitriles.

The reaction of the aldehyde A with the amine C to the intermediate of the formula (VII) is carried out in a condensation reaction with elimination of water, as described above for the reaction of the aldehyde A with the amine B. The stoichiometry between the aldehyde A and the amine C is chosen so that 1 mol of aldehyde A for 1 mol of amine C are used. A solvent-free preparation process is preferred in which the water formed during the condensation is removed from the reaction mixture by applying a vacuum.

The reaction of the intermediate of the formula (VII) with the Michael acceptor of the formula (VIII) is carried out, for example, by mixing the intermediate with a stoichiometric or slightly more than stoichiometric amount of the Michael acceptor of the formula (VIII) and mixing Temperatures of 20 to 110 ⁰ C until complete conversion of the intermediate to the aldimine of the formula (Xl) is heated. The reaction is preferably carried out without the use of solvents.

The aldimines of formula (XI) may optionally be in equilibrium with cyclic forms as exemplified in formula (X). These cyclic forms in the case of aminoaldimines are cyclic aminals, for example imidazolidines or tetrahydropyrimidines; in the case of hydroxyaldehydes, cyclic aminoacetals, for example oxazolidines or tetrahydrooxazines; in the case of mercaptoaldimines, cyclic thioaminals, for example thiazolidines or tetrahydrothiazines.

In the formula (X), R ¹ , R ² , R ³ , R ⁴ and X have the same meaning as described for formula (I). Surprisingly, most aldimines of the formula (XI) do not tend to cyclise. In particular, for aminoaldimines can be shown by IR and NMR spectroscopic methods that these compounds predominantly in the open-chain, so the aldimine form, while the cyclic, ie the aminal form, does not occur or only in traces. This is in contrast to the behavior of the prior art aminoaldimines, as described, for example, in US 4,404,379 and US 6,136,942: namely, those are mainly in the cycloaminal form. Also, hydroxy and mercaptoamines, in which the primary amino group of the hydroxy or the mercapto group are separated by a chain of at least 5 atoms, or by a ring, show little cyclization. The substantial absence of cyclic structures in the aldimines of the formula (XI) is to be regarded as an advantage, in particular with regard to their use in isocyanate-containing compositions, since the aldimines are thereby largely free of those in aminals, oxazolidines and

Thioaminalene occurring basic nitrogen atoms, which the

Could reduce storage stability of the isocyanate-containing composition.

The aldimines of the formula (XI) are odorless. They are stable under suitable conditions, in particular with the exclusion of moisture. Upon entry of moisture, the aldimine groups of aldimines can formally hydrolyze via intermediates into amino groups releasing the corresponding aldehyde A used to make the aldimine. Since this hydrolysis reaction is reversible and the chemical equilibrium lies clearly on the aldimine side, it can be assumed that in the absence of amine-reactive groups only a part of the aldimine groups will be partially or completely hydrolyzed.

A polyurethane polymer D of the formula (I) which is solid at room temperature and has an isocyanate group-containing polyurethane polymer D of the formula (XII) which is solid at room temperature is suitable as a polyurethane polymer D for preparing a room temperature solid, aldimine-containing polyurethane polymer. OCN ^J tI ^R R ^L1 Hi ^N N ^C C ⁰ O] l (XII)

In the formula (XII), p, q and R ^{5 have} the same meaning as described for the formula (I).

Particularly suitable diols for the preparation of a polyurethane polymer D are polyether diols, polyester diols and polycarbonatediols, and also mixtures of these diols.

Particularly suitable polyetherdiols, also called polyoxyalkylenediols, are those which are polymerization products of ethylene oxide, 1,2-propylene oxide, 1,2- or 2,3-butylene oxide, tetrahydrofuran or mixtures thereof, possibly polymerized with the aid of a starter molecule having two active hydrogen atoms such as water, ammonia or compounds having two OH or NH groups such as 1, 2-ethanediol, 1, 2- and 1, 3-propanediol, neopentyl glycol, diethylene glycol, triethylene glycol, the isomeric dipropylene glycols and tripropylene glycols, the isomeric butanediols, Pentanediols, hexanediols, heptanediols, octanediols, nonanediols, decanediols, undecanediols, 1, 3- and 1, 4-cyclohexanedimethanol, bisphenol A, hydrogenated bisphenol A, aniline and mixtures of the aforementioned compounds. Both polyoxyalkylene diols having a low degree of unsaturation (measured according to ASTM D-2849-69 and expressed in milliequivalents of unsaturation per gram of diol (mEq / g)) prepared, for example, by means of so-called double metal cyanide complex catalysts (DMC catalysts) can be used ), as well as polyoxyalkylene diols having a higher degree of unsaturation, prepared for example with the aid of anionic catalysts such as NaOH, KOH or alkali metal alkoxides. Particularly suitable polyether diols are polyoxyalkylene diols, in particular polyoxyethylene diols.

Especially suitable are polyoxyalkylenediols having a degree of unsaturation lower than 0.02 meq / g and having a molecular weight in the range from 1000 to 30,000 g / mol, and also polyoxypropylenediols having a molecular weight of from 400 to 8,000 g / mol. Also particularly suitable are so-called "EO-endcapped" (ethylene oxide-endcapped) polyoxypropylene diols, the latter being special polyoxypropylene-polyoxyethylene diols obtained, for example, by alkoxylating pure polyoxypropylene diols with ethylene oxide after completion of the polypropoxylation and thereby having primary hydroxyl groups. Molecular weight 'or' molar weight 'is understood in the present document always the molecular weight average M _n .

Most suitable polyether diols are those with a

Unsaturation degree lower than 0.02 meq / g and having a molecular weight in the range of 7000 to 30O00, in particular between 10'0OO and 25'00O g / mol.

For example, such polyethers are sold under the trade name ^Acclaim® by Bayer.

Particularly suitable polyester diols are those which are prepared from dihydric alcohols, for example 1,2-ethanediol, diethylene glycol, 1,2-propanediol, dipropylene glycol, 1,4-butanediol, 1,5-pentanediol, 1,6-hexanediol, Neopentyl glycol, or mixtures of the aforementioned alcohols, with organic dicarboxylic acids or their anhydrides or esters, such as succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic, dodecanedicarboxylic, maleic, fumaric, phthalic, isophthalic, terephthalic and hexahydrophthalic or mixtures of the foregoing Acids, and polyester diols from lactones, such as ε-caprolactone.

Particularly suitable polyesterdiols are polyesterdiols of adipic acid, azelaic acid, sebacic acid or dodecanedicarboxylic acid as dicarboxylic acid and of hexanediol or neopentyl glycol as dihydric alcohol. The polyester diols preferably have a molecular weight of from 1000 to 15O00 g / mol, in particular from 1500 to 8000 g / mol, preferably from 1700 to 5500 g / mol. Semi-crystalline, crystalline and amorphous polyester diols in the form of adipic acid / hexanediol polyester, azelaic acid / hexanediol polyester, and dodecanedicarboxylic acid, which are liquid at room temperature, are particularly suitable. acid / hexanediol polyesters. Suitable liquid at room temperature polyester diols are not far below established from room temperature, for example at temperatures between 0 ⁰ C and 25 ⁰ C.

Suitable polycarbonate diols are those which are obtainable by reacting, for example, the abovementioned dihydric alcohols used to form the polyester diols with dialkyl carbonates, diaryl carbonates or phosgene.

Preferred diols are polyesterdiols and polycarbonatediols.

Particularly preferred diols are polyesterdiols, in particular a mixture of an amorphous and a crystalline or partially crystalline polyesterdiol, or a mixture of a liquid at room temperature and a crystalline or partially crystalline polyesterdiol, or a mixture of a partially crystalline and a crystalline polyesterdiol. If a liquid at room temperature polyester diol is used, this is not far below room temperature, in particular at a temperature between 0 ⁰ C and 25 ° C.

Commercially available aliphatic, cycloaliphatic or aromatic diisocyanates, for example the following, can be used as diisocyanates for the preparation of a polyurethane polymer D containing isocyanate groups.

1, 6-hexamethylene diisocyanate (HDI), 2-methylpentamethylene-1,5-diisocyanate, 2,2,4- and 2,4,4-trimethyl-1,6-hexamethylene diisocyanate (TMDI), 1,12-dodecamethylene diisocyanate , Lysine and Lysinesterdiisocyanat, cyclohexane-1, 3- and -1, 4-diisocyanate and any mixtures of these isomers, 1-isocyanato-S ^^ - trimethyl-δ-isocyanatomethyl-cyclohexane (= isophorone diisocyanate or IPDI), perhydro -2,4'- and -4,4'-diphenylmethane diisocyanate (HMDI or Hi ₂ MDI), 1, 4-diisocyanato-2,2,6-trimethylcyclohexane (TMCDI), 1, 3 and 1, 4-bis- (isocyanatomethyl) cyclohexane, m- and p-xylylene diisocyanate (m- and p-XDI), m- and p-tetramethyl-1,3-and -1,4-xylylene diisocyanate (m- and p-TMXDI), bis- (1-isocyanato-1-methylethyl) naphthalene, 2,4- and 2,6-toluene diisocyanate and any mixtures of these isomers (TDI), 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanate and any mixtures of these isomers (MDI), 1, 3 and 1, 4-phenylene diisocyanate, 2, 3,5,6-tetramethyl-1,4-diisocyanatobenzene, naphthalene-1,5-diisocyanate (NDI), 3,3'-dimethyl-4,4'-diisocyanatodiphenyl (TODI), oligomers and polymers of the aforementioned isocyanates, and any mixtures of the aforementioned isocyanates. Preferred are MDI, TDI, HDI, H ₁₂ MDI and IPDI.

The preparation of the polyurethane polymer D is carried out in a known manner directly from the diisocyanates and the diols, or by stepwise adduction, as they are known as chain extension reactions.

It is essential that the polyurethane polymer D has isocyanate groups and is solid at room temperature. In a preferred embodiment, the polyurethane polymer D is prepared via a reaction of at least one diisocyanate and at least one diol, wherein the isocyanate groups are present in a stoichiometric excess over the hydroxyl groups. Advantageously, the ratio between isocyanate and hydroxyl groups, in short "NCO / OH ratio" called, 1.3 to 2.5, in particular 1.5 to 2.2.

The polyurethane polymer D has a molecular weight of preferably more than 1000 g / mol, in particular such between 1200 and 50,000 g / mol, preferably between 2,000 and 30,000 g / mol. Furthermore, the polyurethane polymer D (p + q) has isocyanate groups, where (p + q) is 2.

It is clear to the person skilled in the art that the diols used to prepare the polyurethane polymer D are generally of technical quality and thus represent mixtures of oligomers of different chain length, monomer composition and OH functionality. Thus, technical diols, in particular polyether diols, due to the preparation process, in addition to a predominant proportion of diols also monols, so that their average OH functionality is not exactly 2, but slightly less than 2. On the other hand, technical diols, for example by the Concomitant use of trifunctional starters, monomers or crosslinkers, in addition to diols and monols also contain small proportions of triols, so that their average OH functionality may also be slightly higher than 2.

The reaction between the aldimine of the formula (XI) and the polyurethane polymer D for the aldimine-containing polyurethane polymer of the formula (I) is carried out under known conditions typically used for reactions between the reactive groups involved in the reaction, for example at a temperature of 20 ⁰ C to 100 ⁰ C. It is preferably carried out at a temperature at which the polyurethane polymer D is liquid. The reaction is carried out using a solvent or preferably solvent-free. Optionally, auxiliaries such as catalysts, initiators or stabilizers may be included. The reaction is preferably carried out for aminoaldimines without catalyst, while for hydroxy, mercapto and urea aldehydes the use of a catalyst, as used for the urethanization reaction between isocyanates and alcohols, for example an organotin compound, a bismuth complex, a tertiary amine compound or a combination of such catalysts may be useful.

If the addition reaction between the aldimine of the formula (XI) and the polyurethane polymer D to the polyurethane polymer of the formula (I) stoichiometrically performed, that is, with one molar equivalent of active hydrogen of aldimine (Xl) to one molar equivalent of isocyanate groups of the polyurethane polymer D - whereby its reactive groups are completely implemented - is obtained as addition product of the formula (I) a dialdimine.

Preferably, however, the addition reaction between the aldimine of the formula (XI) and the polyurethane polymer D is carried out substoichiometrically, ie with less than one mole equivalent of active hydrogen of the aldimine (XI) to one mole equivalent of isocyanate groups of the polyurethane polymer D. Thus, the isocyanate groups are only partially reacted, what to at least one aldimine-containing polyurethane polymer of the formula (I) which likewise has isocyanate groups, ie with q = 1.

Preferred aldimine-containing polyurethane polymers of

Formula (I) are those of the formulas (I a), (I b) and (I c),

wherein R ¹ , R ² , R ³ , R ⁴ and R ^{5 have} the meanings already mentioned, and R ^{8 is} a monovalent hydrocarbon radical having 1 to 20 C-

Atoms, which optionally has at least one carboxylic ester, nitrile, nitro, phosphonic acid ester, sulfonic or sulfonic acid ester group.

The aldimine-containing polyurethane polymers of the formula (I) are, like the aldimines of the formula (XI), odorless. They are stable under suitable conditions, in particular with the exclusion of moisture.

When moisture enters their aldimine groups can over

Formally hydrolyze intermediates into amino groups, the corresponding one used to prepare the aldimine of formula (XI)

Aldehyde A is released. In the absence of isocyanate groups, that is to say for polyurethane polymers of the formula (I) where q = 0, it can be assumed that partially or completely hydrolyzing only part of the aldimine groups, since the hydrolysis reaction is reversible and the chemical equilibrium is clearly on the aldimine side. In the case of polyurethane polymers of the formula (I) where q = 1, on the other hand, the amino groups liberated react with the isocyanate groups, which leads to crosslinking of the polyurethane polymer. The reaction of the isocyanate groups with the hydrolyzing aldimine groups need not necessarily take place via amino groups. Of course, reactions with intermediates of the hydrolysis reaction are possible. For example, it is conceivable that a hydrolyzing aldimine group in the form of a hemiaminal reacts directly with an isocyanate group.

Throughout the document, the terms "crosslinking" or "crosslinking reaction" refer to the process of formation of high molecular weight polyurethane plastics caused by the chemical reaction of isocyanate groups, even if predominantly chains are formed.

The compositions described may optionally contain an isocyanate group-containing polyurethane polymer P.

It is preferably a polyurethane polymer D, as has already been described for the preparation of an aldimine-containing polyurethane polymer of the formula (I), ie a solid at room temperature, isocyanate-containing polyurethane polymer.

The aldimine groups present in the composition are typically present at a slightly superstoichimetric, stoichiometric or substoichiometric ratio relative to the isocyanate groups present in the composition. The ratio between aldimine groups and isocyanate groups is advantageously 0.3 to 1.1, in particular 0.5 to 1.05.

If the aldimine-containing polyurethane polymer of the formula (I) has no isocyanate groups, ie q in formula (I) is zero, or if the aldimine group-containing polyurethane polymer of the formula (I) has two or more aldimine groups, that is, for example, a compound of

Formula (I c), the composition contains a mandatory Isocyanate group-containing polyurethane polymer P. In this way, a suitable ratio of aldimine groups to isocyanate groups is achieved, as shown above.

If the aldimine-containing polyurethane polymer of the formula (I) has only one aldimine group and one isocyanate group, that is, for example, a compound of the formula (I a) or (I b), the presence of a polyurethane polymer P is optional, since in this case also a Composition without polyurethane polymer P has a suitable ratio of aldimine groups to isocyanate groups.

The composition described has a surprisingly low content of monomeric diisocyanates. This is particularly advantageous for use as a hotmelt adhesive, since monomeric diisocyanates outgas during application and can pose a health burden for the processor as irritating, sensitizing or toxic substances. The content of monomeric diisocyanates is very low, especially when the polyurethane polymer composition mainly contains a polyurethane polymer of the formula (I) which is obtained by the substoichiometric reaction of a polyurethane polymer D with an aldimine of the formula (XI), in particular less than one half molar equivalent active hydrogen of aldimine (XI) to one molar equivalent of isocyanate groups of polyurethane polymer D.

In a preferred preparation process of the composition described, all components of the composition containing monomeric diisocyanates are present in the reaction mixture in the reaction of the aldimines of formula (XI) with the isocyanate group-containing polyurethane polymer D. Compositions prepared in this way have the lowest content of monomeric diisocyanates. The composition described preferably has a content of monomeric diisocyanates of <0.3% by weight, more preferably of <0.2% by weight, and in particular of <0.1% by weight. The composition described optionally contains further constituents, as commonly used in the prior art, in particular:

Non-reactive thermoplastic polymers, such as homo- or copolymers of unsaturated monomers, in particular from

A group comprising ethylene, propylene, butylene, isobutylene, isoprene, vinyl acetate or higher esters thereof, and (meth) acrylate, wherein ethylene-vinyl acetate copolymers (EVA), atactic poly-α-olefins (APAO), polypropylenes (PP) and polyethylenes (PE ) are particularly suitable; Catalysts for the reaction of the aldimine groups and / or the

Isocyanate groups, in particular acids or compounds hydrolyzable to acids, for example organic carboxylic acids such as phthalic anhydride or hexahydrophthalic anhydride, silyl esters of organic carboxylic acids, organic sulfonic acids such as methanesulfonic acid, p-toluenesulfonic acid or 4-dodecylbenzenesulfonic acid, or other organic or inorganic acids; Metal compounds, for example tin compounds such as dibutyltin diacetate, dibutyltin dilaurate, dibutyltin distearate, dibutyltin diacetylacetonate, dioctyltin dilaurate, dibutyltin dichloride and dibutyltin oxide, tin (II) carboxylates, stannoxanes such as laurylstannoxane, bismuth compounds such as bismuth (III) octoate, bismuth (III) neodecanoate or bismuth (III) -oxinate; tertiary amines, for example 2,2'-dimorpholinodiethyl ether and other morpholine ether derivatives, 1, 4-diazabicyclo [2.2.2] octane and 1, 8-

Diazabicyclo [5.4.0] undec-7-ene; Combinations of said catalysts, in particular mixtures of acids and metal compounds, or of metal compounds and tertiary amines;

Reactive diluents or crosslinkers, for example oligomers or polymers of diisocyanates such as MDI, PMDI, TDI, HDI, 1,1-dodecamethylene diisocyanate, cyclohexane-1,3,3 or 1,4-diisocyanate, IPDI, perhydro-2,4'-diisocyanate and - 4,4'-diphenylmethane diisocyanate (Hi ₂ MDI), 1, 3- and 1, 4-tetramethylxylylene diisocyanate, in particular isocyanurates, carbodiimides, uretonimines, biurets, allophanates and iminooxadiazinediones of said diisocyanates, adducts of diisocyanates with short-chain polyols, Adipic acid dihydrazide and other dihydrazides, as well as blocked hardeners in the form of polyaldimines, polyketimines, oxazolidines or polyoxazolidines;

Fillers, plasticizers, adhesion promoters, in particular silane-containing compounds, UV absorbers, UV or heat stabilizers, antioxidants, flame retardants, optical brighteners,

Pigments, dyes and drying agents, and other substances commonly used in isocyanate-containing compositions.

In a preferred embodiment, the composition described is free of carbon black.

In a further preferred embodiment, the composition described is completely free of fillers. Such a composition is particularly suitable for the bonding of substrates, in which at least one of the substrates to be bonded is transparent or translucent. Suitably, the sum of the solid at room temperature,

Aldimine-containing polyurethane polymer of the formula (I) and the isocyanate group-containing polyurethane polymer P 40 to 100% by weight, in particular 75 to 100% by weight, preferably 80 to 100% by weight, based on the total composition.

The composition described is prepared and stored in the absence of moisture. In a suitable climate-proof packaging or arrangement, such as in a keg, bag or cartridge, it has excellent storage stability. The terms "storage-stable" and "storage stability" in the context of a composition in the present document refers to the fact that the viscosity of the composition at the application temperature with suitable storage in the period considered not or at most so strong increases that the composition of the intended way remains usable.

For the mode of action of a reactive hot-melt adhesive, it is important that the adhesive is meltable, that is, in the Application temperature has a sufficiently low viscosity to be applied, and that it builds up as quickly as possible sufficient adhesive strength, even before the crosslinking reaction is complete with humidity (initial strength). It has been found that the compositions described have in the conventional hot melt adhesives application temperatures ranging from 85 ⁰ C to 200 ⁰ C, typically 120 ⁰ C to 160 ⁰ C, a well-manageable viscosity, and that they sufficiently rapidly on cooling, a good Build up adhesive strength.

In the application, the composition described in

Contact with moisture, especially in the form of humidity. In addition to the physical hardening due to solidification on cooling, the chemical crosslinking with moisture also sets in, mainly by hydrolyzing the existing aldimine groups by moisture and reacting quickly with existing isocyanate groups in the manner already described. Excess isocyanate groups also crosslink with moisture in a known manner.

The moisture needed for chemical crosslinking can either come from the air (humidity), or else the composition can be contacted with a water-containing component, for example by brushing or spraying, or it can be water-applied to the composition upon application containing component may be added, for example in the form of a water-containing paste, which, for example via a static mixer, is mixed.

The compositions described exhibit a greatly reduced tendency to form bubbles when crosslinked with moisture, since little or no carbon dioxide is formed in the crosslinking due to the presence of aldimine groups, depending on the stoichiometry. In a preferred embodiment, the composition described is used as a reactive polyurethane hotmelt adhesive, PUR-RHM for short.

When used as PUR-RHM, the composition becomes

Bonding of a substrate S1 and a substrate S2 used. Such a bond comprises the steps of i) heating a composition as described above to a temperature between 85 ⁰ C and 200 ⁰ C, in particular between 120 ⁰ C and 160 ⁰ C; ii) applying the heated composition to a substrate

S1; iii) contacting the applied composition with a second substrate S2 within open time; wherein the second substrate S2 is made of the same or a different material as the substrate S1.

Step iii) is typically followed by a step iv) of chemically crosslinking the composition with moisture. The person skilled in the art understands that the crosslinking reaction, depending on factors such as the composition used, the substrates, the temperature, the ambient humidity and the adhesive geometry, can already begin during the bonding. However, the majority of crosslinking generally occurs after bonding.

If desired, the substrates S1 and / or S2 can be pretreated prior to applying the composition. Such pretreatments include in particular physical and / or chemical cleaning and activation processes, for example grinding, sandblasting, brushing, corona treatment, plasma treatment, flaming, etching or the like, or treatment with cleaners or solvents or the application of a primer, a primer solution or a primer. The substrates S1 and S2 may be a variety of materials. In particular, plastics, organic materials such as leather, fabrics, paper, wood, resin-bonded wood materials, resin-Texil composites, glass, porcelain, ceramics and metals and metal alloys, in particular painted or powder-coated metals and metal alloys are suitable , Particularly suitable plastics are polyvinyl chloride (PVC), acrylonitrile-butadiene-styrene copolymers (ABS), SMC (sheet molding composites), polycarbonate (PC), polyamide (PA), polyesters, polyoxymethylene (POM), polyolefins (PO ), in particular polyethylene (PE), polypropylene (PP), ethylene / propylene copolymers (EPM) and ethylene / propylene-diene terpolymers (EPDM), preferably plasma-corona or flame-treated PP or PE.

As preferred materials for the substrates S1 and S2 are transparent materials, in particular transparent plastic films. Another preferred transparent material is glass, especially in the form of a disk.

The thickness of the adhesive layer (bond thickness) is typically 10 microns or more. In particular, the bond thickness is between 10 microns and 20 millimeters, especially between 80 microns and 500 microns. For thick layers, however, crosslinking is usually very slow due to slow water diffusion.

The described composition is used in particular in an industrial manufacturing process.

In particular, the composition described is suitable as

PUR-RHM for gluing, in which the gluing point is visible. Thus, on the one hand, it is particularly suitable for the bonding of glass, in particular in vehicle and window construction. On the other hand, it is particularly suitable for the gluing of transparent packaging. The bonding process results in articles. Such articles are on the one hand, in particular articles from the transport, furniture or textile industry. The automotive industry is preferred as a means of transport.

Exemplary such articles are water or land vehicles such as automobiles, buses, trucks, trains or ships; Automotive interior trim parts, such as headliner, sun visor, instrument panel, door side panel, parcel shelf, and the like; Wood fiber materials from the shower and bath area; Furniture decorative films, membrane films with textiles such as cotton, polyester films in the clothing sector or textiles with foams for automotive equipment.

On the other hand, such articles are in particular articles from the packaging industry. In particular, such an article is a transparent packaging.

The compositions described comprising a) at least one room temperature solid aldimine group-containing polyurethane polymer of the formula (I), and b) optionally at least one isocyanate group-containing polyurethane polymer P, have a number of advantages over the prior art when used as reactive hotmelt adhesive compositions Technology on.

Thus, they have a greatly reduced content of monomeric diisocyanates and thereby result in their use to a greatly reduced burden on the processor with harmful diisocyanate vapors. With the described compositions, hot-melt adhesive compositions based on commercially available, readily available diisocyanates, such as 4,4'-MDI or IPDI, with extremely low monomeric diisocyanate content are available. The low content of monomeric diisocyanates is achieved by the reaction of polyurethane polymers D with aldimines of the formula (XI), where in the Aldimines contained active hydrogen apparently preferentially reacted with the present in polyurethane polymer D monomeric diisocyanates.

Furthermore, when used as a hot-melt adhesive, the compositions described have a high crosslinking speed, even if they contain only slowly reacting aliphatic isocyanate groups, such as those of IPDI or Hi ₂ MDI. Prior art pure aliphatic diisocyanate-based PUR-RHMs generally have such low cure rate that they are not useful for most applications. Furthermore, the compositions described show a greatly reduced tendency to form bubbles, because in the crosslinking reaction of isocyanate groups with hydrolyzing aldimine groups no carbon dioxide is formed, in contrast to crosslinking of isocyanate groups with moisture. In addition to these advantages, when used as a hotmelt adhesive, the compositions described exhibit similarly good properties as the prior art systems, namely rapid bond strength, good heat resistance, and high ultimate strength with good ductility, the final mechanical properties being very broad Adjust the range to the needs of a gluing application.

In another aspect, the invention relates to a process for reducing the content of monomeric diisocyanates in isocyanate group-containing polyurethane polymers or in compositions containing isocyanate group-containing polyurethane polymers by reacting the isocyanate group-containing polyurethane polymers with at least one aldimine of the formula (XI). Examples

a) Description of test methods

The total content of aldimine groups and free amino groups in the compounds prepared ("amine content") was determined by titration (with 0.1 N HCIO ₄ in glacial acetic acid, against crystal violet) and is always given in mmol NH ₂ / g (even if it is not only primary amino groups are involved).

The content of monomeric diisocyanates was determined by means of HPLC (detection via photodiode array) and is given in% by weight based on the total composition.

The viscosity was measured at the temperature indicated in each case with a Brookfield viscometer with spindle No. 27 and 10 revolutions per minute.

The open time was determined as follows: The cooperation reduction was at a temperature of 150 ⁰ C in a thickness of 500 microns on silicone-coated paper mounted. This test specimen was then placed on a surface temperature-warm substrate. As soon as a piece of paper that is pressed lightly onto the adhesive separates from the adhesive

Hess, the open time was over. The adhesive then hardened and became firm.

The tensile strength and the elongation at break were based on

DIN 53504 determined on test specimens with a layer thickness of 500 microns and the dimensions 120 mm x 20 mm. The films for preparing the test specimens were applied at an adhesive temperature of 140 ⁰ C and then stored for 2 weeks at a relative 23 ⁰ C and 50% humidity.

b) Preparation of Aldimines of the Formula (XI) Aldimine 1

30.13 g (0.106 mol) of 2,2-dimethyl-3-lauroyloxypropanal were placed in a round-bottomed flask under a nitrogen atmosphere. Under strong

Stirring was from a dropping funnel within 5 minutes 15.00 g

(0.096 mol) of N-cyclohexyl-1, 3-propanediamine added, the temperature of the reaction mixture to 36 ⁰ C increase. After that, the fleeting Ingredients removed in vacuo (10 mbar, 80 ⁰ C). This gave 43.2 g of a colorless, liquid at room temperature, clear and odorless liquid, which had an amine content of 4.39 mmol NH ₂ / g.

Aldimin 2

28.06 g (0.099 mol) of 2,2-dimethyl-3-lauroyloxypropanal were placed in a round-bottomed flask under a nitrogen atmosphere. With vigorous stirring from a dropping funnel within 3 minutes 10:00 g (0.095 mol) of 2- (2-aminoethoxy) ethanol (Diglycolamine ^® agent; Huntsman) were added, the temperature of the reaction mixture rose to 40 ⁰ C. Thereafter, the volatiles were removed in vacuo (10 mbar, 80 ⁰ C). This gave 36.3 g of a colorless, liquid at room temperature, clear and odorless liquid, which had an amine content of 2.58 mmol NH ₂ / g.

Aldimin 3

69.31 g (0.244 mol) of 2,2-dimethyl-3-lauroyloxypropanal were placed in a round-bottomed flask under a nitrogen atmosphere. With vigorous stirring 14.72 g (0.112 mol) of dipropylene triamine were added within 5 minutes from a dropping funnel, wherein the temperature of the reaction mixture increased to 36 ⁰ C. Thereafter, the volatiles were removed in vacuo (10 mbar, 80 ⁰ C). This gave 79.7 g of a colorless, liquid at room temperature, clear and odorless liquid, which had an amine content of 4.17 mmol NH ₂ / g.

c) Preparation of polyurethane polymers D

Polyurethane polymer D1

800 g of Dynacoll ^® 7250 (liquid polyester diol, OH number 21 mg KOH / g; Degussa), 200 g of Dynacoll ^® 7360 (crystalline polyester diol, OH number 30 mg KOH / g, melting point of 55 ⁰ C; Degussa) and 102 g of 4,4'-diphenylmethane diisocyanate (4,4'-MDI; Desmodur ^® 44 MC L, Bayer) were according to a known method at 100 ⁰ C to give an NCO-terminated polyurethane polymer vice puts. The reaction product had a titrimetrically determined content of free isocyanate groups of 1.5% by weight and was solid at room temperature.

Polyurethane Polymer D2 The same diol mixture as in the polyurethane polymer D1 was used with

102 g of 2,4'-diphenylmethane diisocyanate (2,4'-MDI; Lupranat MCI ^®, BASF) according to a known method at 100 ⁰ C to give an NCO-terminated polyurethane polymer reacted. The reaction product had a titrimetrically determined content of free isocyanate groups of 1.5% by weight and was solid at room temperature.

Polyurethane polymer D3

The same diol mixture as in the polyurethane polymer D1 was charged with 107 g of 4,4'-dicyclohexylmethane diisocyanate (H ₁₂ MDI; Desmodur ^® W, Bayer) were reacted by a known method at 100 ⁰ C to give an NCO-terminated polyurethane polymer. The reaction product had a titrimetrically determined content of free isocyanate groups of 1.5% by weight and was solid at room temperature.

Polyurethane polymer D4

The same diol mixture as in the polyurethane polymer D1 was charged with 90.4 g of isophorone diisocyanate; reacted by a known method at 100 ⁰ C to give an NCO-terminated polyurethane polymer (IPDI Vestanat ^® IPDI, Degussa). The reaction product had a titrimetrically determined content of free isocyanate groups of 1.5% by weight and was solid at room temperature.

d) Preparation of Hot Melt Adhesive Compositions Example 1

95.0 parts by weight of polyurethane polymer D1 and 7.7 parts by weight of aldimine 1 were homogeneously mixed at a temperature of 130 ⁰ C and left at 130 ⁰ C for 1 hour. The formed aldimine and isocyanate Group containing polyurethane polymer was stored at room temperature with exclusion of moisture.

Example 2

95.0 parts by weight of polyurethane polymer D1 and 6.5 parts by weight of aldimine 2 were homogeneously mixed at a temperature of 130 ⁰ C and left at 130 ⁰ C for 1 hour. The formed aldimine and isocyanate group-containing polyurethane polymer was stored at room temperature with exclusion of moisture.

Example 3

95.0 parts by weight of polyurethane polymer D1 and 8.1 parts by weight

Aldimine 3 were homogeneously at a temperature of 130 ⁰ C and the mixture left for 1 hour at 130 ⁰ C. The formed aldimine and isocyanate groups-containing polyurethane polymer was at room temperature under

Exclusion of moisture stored.

Example 4 (comparison)

100 parts by weight of polyurethane polymer D1.

Table 1: Properties of Examples 1 to 4 Example 5

Example 5 was carried out as Example 1, wherein instead of the polyurethane polymer D1, the polyurethane polymer D2 was used.

Example 6

Example 6 was carried out as Example 2, wherein instead of the polyurethane polymer D1, the polyurethane polymer D2 was used.

Example 7 Example 7 was carried out as Example 3, using instead of

Polyurethane polymer D1, the polyurethane polymer D2 was used.

Example 8 (comparison)

100 parts by weight of polyurethane polymer D2.

Table 2: Properties of Examples 5 to 8

Example 9

Example 9 was carried out as Example 1, wherein instead of the polyurethane polymer D1, the polyurethane polymer D3 was used.

Example 10

Example 10 was carried out as Example 2, wherein instead of the polyurethane polymer D1, the polyurethane polymer D3 was used. Example 11

Example 11 was carried out as Example 3, wherein instead of the polyurethane polymer D1, the polyurethane polymer D3 was used.

Example 12 (comparison)

100 parts by weight of polyurethane polymer D3.

Table 3: Properties of Examples 9 to 12

Example 13 Example 13 was carried out as Example 1, using instead of

Polyurethane polymer D1, the polyurethane polymer D4 was used.

Example 14

Example 14 was carried out as Example 2, wherein instead of the polyurethane polymer D1, the polyurethane polymer D4 was used.

Example 15

Example 15 was carried out as Example 3, wherein instead of the polyurethane polymer D1, the polyurethane polymer D4 was used.

Example 16 (comparison)

100 parts by weight of polyurethane polymer D4.

Table 4: Properties of Examples 13 to 16

From the examples shown, it can be seen that the compositions according to the invention have significantly lower contents of monomeric diisocyanates than the corresponding prior art compositions without aldimine groups, their applicability being ensured as reactive hot-melt adhesives.

Claims

claims

1. Composition comprising a) at least one room temperature solid, aldimine-containing polyurethane polymer of the formula (I)

where p is an integer of 1 or 2 and q is an integer of 0 or 1, with the proviso that p + q = 2; R ^{1 is} either a monovalent hydrocarbon radical having 6 to 30 C atoms, which optionally has at least one heteroatom, in particular in the form of ether oxygen, is, or is a substituent of the formula (II)

in which

R ^{6 is} a divalent hydrocarbon radical having 2 to 20 C atoms, which optionally has at least one heteroatom, in particular in the form of ether oxygen; and

R ^{7 is} a monovalent hydrocarbon radical having 1 to 20 C atoms; R ² and R ³ are each, independently of one another, each represent a monovalent hydrocarbon radical having 1 to 12 carbon atoms; or together form a bivalent hydrocarbon radical having from 4 to 20 carbon atoms which is part of an optionally substituted carbocyclic ring having from 5 to 8, preferably 6, carbon atoms; and where

R ^{4 is} a divalent hydrocarbon radical having 2 to 12 C atoms, which optionally has at least one heteroatom, in particular in the form of ether oxygen or tertiary amine nitrogen; R ^{5 is} the residue of a room temperature solid, isocyanate group-containing polyurethane polymer D after removal of (p + q) isocyanate groups; X is O, S or NR ⁸ , where R ^{8 is} either a monovalent hydrocarbon radical having 1 to 20 C atoms, which optionally has at least one carboxylic acid ester, nitrile, nitro, phosphonic ester, sulfonic or sulfonic acid ester group, is or is a substituent of the formula (III)

b) at least one isocyanate group-containing polyurethane polymer P, if q in formula (I) is zero, or if X in formula (I) is NR ⁸ with R ⁸ as a substituent of formula (III).

2. Composition according to claim 1, characterized in that p = 1 and q = 1.

3. A composition according to claim 1 or 2, characterized in that the solid at room temperature, having isocyanate groups

Polyurethane polymer D is prepared from at least one diisocyanate and at least one diol.

4. Composition according to one of the preceding claims, characterized in that the polyurethane polymer P is prepared from at least one diisocyanate and at least one diol.

5. A composition according to claim 3 or 4, characterized in that the diol is a polyester diol.

6. A composition according to claim 3 or 4, characterized in that the diol is either a mixture of an amorphous and a crystalline or partially crystalline polyester diol, or a mixture of liquid at room temperature and a crystalline or teilkri- crystalline polyester diol, or a mixture of a semi-crystalline and a crystalline polyester diol, wherein the liquid at room temperature polyester diol at a temperature between 0 ⁰ C and 25 ⁰ C is solid.

7. A composition according to any one of claims 3 to 6, character- ized in that the diisocyanate is MDI, HDI, TDI, Hi ₂ MDI or IPDI.

8. Composition according to one of the preceding claims, characterized in that X = O or NR ⁸ .

9. A composition according to any one of the preceding claims, characterized in that R ² = R ³ = methyl and R ^{1 is} a monovalent hydrocarbon radical having 11 to 30 carbon atoms.

10. The composition according to any one of the preceding claims, characterized in that the sum of the solid at room temperature, aldimine containing polyurethane polymer of formula (I) and the isocyanate group-containing polyurethane polymer P 40 - 100% by weight, in particular 75 - 100% by weight preferred 80 - 100

% By weight, based on the total composition.

11. A composition according to any one of the preceding claims, characterized in that the compound of formula (I) is prepared by reacting an aldimine of formula (XI) with an isocyanate group-containing polyurethane polymer of formula (XII)

OCN + - RM-NCO (XII).

JP L Jc

12. The composition according to claim 11, characterized in that the aldimine of the formula (XI) in a ratio of less than one molar equivalent of active hydrogen of aldimine to a mole equivalent

Isocyanate groups of the polyurethane polymer D is used.

13. A composition according to any one of the preceding claims, characterized in that the content of monomeric diisocyanates <0.3% by weight, preferably <0.2% by weight, in particular <0.1

% By weight, based on the total composition.

14. A cured composition obtained by the reaction of moisture with a composition according to any one of claims 1 to 13.

15. Use of a composition according to any one of claims 1 to 13 as a hot-melt adhesive.

16. Use according to claim 15, characterized in that the use takes place in the interior of vehicles or buildings.

17. Use according to claim 15 or 16 as an adhesive in industrial production or repair or in civil engineering or structural engineering or in the interior of means of transport or structures.

18. A method of bonding substrates S1 and S2 comprising the steps i) heating a composition according to any one of claims 1 to 13 to a temperature between 85 ⁰ C and 200 ⁰ C, in particular between 120 ⁰ C and 160 ⁰ C; ii) applying the heated composition to a substrate S1; iii) contacting the applied composition with a second

Substrate S2 within open time; wherein the second substrate S2 is made of the same or a different material as the substrate S1.

19. Process according to claim 18, characterized in that step iii) is followed by a step iv) of chemical crosslinking of the composition with moisture.

20. The method according to claim 18 or 19, characterized in that at least one of the substrates S1 or S2 is a plastic, an organic material such as leather, cloth, paper, wood, resin-bonded wood material, resin-textile composite material, glass, porcelain, Ceramics, a metal is a metal alloy, in particular a painted or powder-coated metal or metal alloy.

21. The method according to any one of claims 18 to 20, characterized in that the composition in a thickness of more than 10 micrometers, in particular from 10 micrometers to 20 millimeters, preferably from 80 micrometers to 500 micrometers, is applied.

22. A bonded article, which is produced by means of a method for bonding according to one of claims 18 to 21.

23. A bonded article according to claim 22, characterized in that the article is a means of transport, in particular a vehicle by sea or by land, preferably an automobile, a bus, a truck, a train or a ship, or a part thereof.

24. A process for reducing the content of monomeric diisocyanates in polyurethane polymers containing isocyanate groups or in compositions containing polyurethane polymers containing isocyanate groups by reacting the isocyanate group-containing polyurethane polymers with at least one aldimine of the formula (XI),

wherein R ^{1 is} either a monovalent hydrocarbon radical having 6 to 30 carbon atoms, which optionally has at least one heteroatom, in particular in the form of ether-oxygen, is, or is a substituent of the formula (II)

wherein R ^{6 is} a divalent hydrocarbon radical having 2 to 20 C-atoms, which optionally at least one Heteroatom, especially in the form of ether oxygen; and

R ^{7 is} a monovalent hydrocarbon radical having 1 to 20 C atoms;

R ² and R ³ are each, independently of one another, each represent a monovalent hydrocarbon radical having 1 to 12 carbon atoms; or together with a divalent hydrocarbon radical with 4 to

Form 20 C atoms which is part of an optionally substituted carbocyclic ring having 5 to 8, preferably 6, C atoms; and where

R ^{4 is} a divalent hydrocarbon radical having 2 to 12 C atoms, which optionally contains at least one heteroatom, in particular in the form of ether oxygen or tertiary amine nitrogen, is;

R ^{5 is} the residue of a room temperature solid isocyanate group-containing polyurethane polymer D after removal of (p + q) isocyanate groups;

X is O, S or NR ⁸ , where

R ^{8 is} either a monovalent hydrocarbon radical having 1 to 20 C atoms, which optionally has at least one carboxylic acid ester, nitrile, nitro, phosphonic ester, sulfonic or sulfonic acid ester group, is, or is a substituent of formula (III)