DE2330211A1 - LACTAM ADDITION COMPOUNDS AS ACCELERATORS FOR THE CROSSLINKING OF POLYURETHANES WITH POLYISOCYANATES - Google Patents

Description

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Sft-each ⁵ O ⁹ Leverkusen, Bayerwerk

13. JUAfI1973

Lactam addition compounds as accelerators for the crosslinking of polyurethanes with polyisocyanates

It is known, solvent resistant polyurethane coatings by producing solutions of higher molecular weight polyurethanes which still contain small amounts of terminal hydroxyl groups contain, mixed with solutions of relatively high molecular weight, more than divalent polyisocyanates, the solutions applies and then crosslinked through prolonged baking.

Since the crosslinking reaction proceeds too slowly for technical purposes, it must be replaced by suitable catalysts such as, for example, organic basic nitrogen compounds are accelerated. In practice they are used as accelerators for coating purposes mostly tertiary amines, for example the reaction product of phenyl isocyanate and methyl diethanolamine, are used. However, the relatively low catalytic effect of these compounds means that the coatings only are fully crosslinked after 1-3 days, so that combinations of this type are only useful for direct layers * These systems are less suitable for reverse coatings because the separation of the coating from the Separation carrier is only possible after at least a few hours after the drying process. With direct coating The mere addition of a reaction accelerator is not sufficient, but it is generally still a

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Anti-caking agents, for example a fatty acid titanate, are added. Is technically used the well-known strong acceleration effect of polyvalent heavy metal salts, for example _o tin compounds to isocyanate reactions. In this class of product, however, it is particularly disruptive that catalysts accelerate not only the forward but also the reverse reaction (hydrolysis). This is an effect which, of course, is undesirable, especially in the case of durable consumer goods, such as those represented by textile coatings.

It is known from DOS 2 117 576 that lactams are the reaction of polyisocyanates with water, diols and / or diamines accelerate extremely fast. The reason for this is that the chain extender is present in the reaction mixture is present in "activated form", namely as an addition compound to the lactam (such addition compounds are first described in DOS 2 062 288). In DOS 2 117 576 it is described that when using such Lactam-activated chain extender, high molecular weight, easily soluble, completely uncrosslinked and linear diisocyanate polyaddition compounds can be manufactured, i.e. products that do not contain any biuret or »allophanate groups.

Surprisingly, however, it has now been found that small amounts of such lactam associates, especially associates between lactams and bifunctional hydroxy compounds, represent valuable accelerators for the crosslinking of polyurethanes with polyisocyanates. Really important is that the lactam adducts are excellent release agents and antiblocking agents at the same time and on the other hand, that the accelerating effect of the catalysts to be used according to the invention does not result in a reduction the hydrolysis stability of those prepared according to the invention Coatings is connected.

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• ο ·

The invention thus provides a method for coating and laminating substrates with solutions of polyurethanes, the bifunctional or higher functional isocyanates as crosslinking agents and catalysts for the crosslinking reactions contain, which is characterized in that associations between lactams and alcohols, thioalcohols, Amines, hydrazines, oximes or water can be used.

According to the invention, associations of lactams of the general formula are preferred

CH ₀ -C = O

R-X N-H

X stands for a CH group, in which case R is hydrogen and

m is an integer from zero to 9 or X is a nitrogen atom, in which case R is an aliphatic radical, an araliphatic radical or an optionally by lower alkyl radical

substituted pyridine radical and m is the number 3,

with an alcohol and / or thioalcohol of any constitution in which per mole of the lactam and / or azalactam 0.3 to 4 mol, preferably 1.0-3 mol of a mono- or polyfunctional one Alcohol or thioalcohol are present, used as a reaction accelerator "Here it is advantageous the amount of isocyanate consumed by the adduct itself must be taken into account in the application formulation by crosslinking of the polyaddition product, the additional amount of polyisocyanate corresponding to the lactam associate is added will.

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Examples of the abovementioned lactams are in particular the lactams of cu-aminocarboxylic acids, such as 3-aminopropionic acid, 4-aminobutyric acid, 5-aminovaleric acid, 6-aminocaproic acid, 10-aminocapric acid; N-substituted Azalactams such as l-N-methylhexahydro-l ^ -diazepinon- (3), 1-N-butyl-hexahydro-1,4-diazepinon- (3), 1-N-benzylhexahydro-1,4-diazepinon- (3 ), l-N-e (-Pyridyl-hexahydro-l, 4-diazepinon- (3) etc. Preferred lactams are butyrolactam, valerolactam, 1-N-methylhexahydro-1,4-diazepinon- (3) and especially £ -Caprοlactam "

In principle, the most varied of addition compounds mentioned in DOS 2 062 288, including associations of water, amines, hydrazines, oximes, monoalcohols or basic monoalcohols such as N, N-dimethylethanolamine, can be used in the process according to the invention. However, lactam associates with bi- and trifunctional alcohols are preferred. Associates of 1 mole caprolactam and 1 mole of ethylene glycol £ or £ 1 mole caprolactam and 1 mole of N-methyl-diethanolamine are particularly preferably used. The associates of t -caprolactam and 1 mol of trimethylolpropane, which are liquid at room temperature, are also of great interest for increasing the degree of crosslinking while at the same time having a good accelerating effect.

The lactam addition products mentioned are in the inventive method in an amount of 0.2 to 4 wt _o -%, preferably 0.3 to 0.6 wt .- 6, based on the total amount of polyurethane and crosslinking agent used ,,?

The polyurethanes used in the process according to the invention are generally linear, readily soluble products with a molecular weight of preferably more than 5000, particularly preferably 10,000-40,000. They are known per se Way from higher molecular weight polyols, diisocyanates and optionally low molecular weight diols and / or diamines

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at an equivalent ratio of NCO / OH + Nf ^) of ~ 1. The higher molecular weight polyols are those with a molecular weight of 800 to 10,000, preferably 1,000 to 6,000, used, e.g. "at least two, but preferably 2 to 4, Polyesters, polyethers, polythioethers, polyacetals, polycarbonates or polyesteramides containing hydroxyl groups, such as they for the production of homogeneous and of cellular Polyurethanes are known per se.

The possible polyesters containing hydroxyl groups are, for example, reaction products of polyvalent, preferably dihydric and optionally additionally trihydric alcohols with polybasic, preferably dibasic, carboxylic acids ,, Instead of the free polycarboxylic acids, the corresponding polycarboxylic acid anhydrides or corresponding Polycarboxylic acid esters of lower alcohols or mixtures thereof can be used to produce the polyesters. the Polycarboxylic acids can be aliphatic, cycloaliphatic, aromatic and / or heterocyclic in nature and optionally substituted, for example by halogen atoms, and / or be unsaturated. Examples include: succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, Phthalic acid, isophthalic acid »trimellitic acid, phthalic anhydride, Tetrahydrophthalic anhydride, hexahydrophthalic anhydride, Endomethylenetetrahydrophthalic anhydride, glutaric anhydride, maleic acid, maleic anhydride, fumaric acid, dimeric and trimeric fatty acids such as oleic acid, optionally mixed with monomeric fatty acids, dimethyl terephthalate and terephthalic acid bis-glycol esters. As multi-valued Alcohols come e.g. ethylene glycol, propylene glycol- (1,2) and - (1,3), butylene glycol- (1,4) and - (2,3), hexanediol- (1,6), octanediol- (1,8), neopentyl glycol, cyclohexanedimethanol ^ 1 ^ -Bis-hydroxymethylcyclohexane), 2-methyl-1,3-propanediol, Glycerine, trimethylolpropane, hexanetriol- (1,2,6), butanetriol- (1,2,4), Trimethylolethane, also diethylene glycol,

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Triethylene glycol, tetraethylene glycol, polyethylene glycols, dipropylene glycol, polypropylene glycols, dibutylene glycol and polybutylene glycols in question. Polyesters made from lactones, for example β-caprolactone or hydroxycarboxylic acids, for example _o ε-hydroxycaproic acid, can also be used.

Also according to the invention in question, at least two, preferably two to three, hydroxyl-containing polyethers are those of the type known per se and are, for example, by polymerizing epoxides such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorohydrin with themselves, z _o B. in the presence of BF ,, or by addition of these epoxides, optionally in a mixture or one after the other, to starting components with reactive hydrogen atoms such as alcohols or amines, e.g. water, ethylene glycol, propylene glycol- (1,3) or - (1,2), Trimethylolpropane, 4,4'-dihydroxydiphenylpropane, aniline, ammonia, ethanolamine, ethylenediamine are produced .. In many cases those polyethers are preferred which predominantly (up to 90% by weight, based on all OH groups present in the polyether) have primary OH groups exhibit. Polyethers modified by vinyl polymers, such as those formed by the polymerization of styrene and acrylonitrile in the presence of polyethers (American patents 3,383,351, 3,304,273, 3,523,093, 3,110,695, German patent I.I52.536), are suitable, as well as polybutadienes containing OH groups.

Among the polythioethers are in particular the condensation products of thiodiglycol with itself and / or with other glycols, dicarboxylic acids, formaldehyde, aminocarboxylic acids or amino alcohols listed. Depending on the co-components, the products are polythio mixed ethers, Polythioether esters or polythioether ester amides.

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As polyacetals come, for example, those from glycols, such as diethylene glycol, triethylene glycol, 4,4 ^! -Dioxäthoxy-diphenyldimethylmethan, hexanediol and formaldehyde preparable compounds in question. Polyacetals suitable according to the invention can also be prepared by polymerizing cyclic acetals.

Polycarbonates containing hydroxyl groups are those of the type known per se, which can be obtained, for example, by reaction of diols such as propanediol (1,3), butanediol (1,4) and / or hexanediol (1,6), diethylene glycol, triethylene glycol or tetraethylene glycol with diaryl carbonates, e.g., diphenyl carbonate or phosgene, can be produced »

The polyester amides and polyamides include, for example, those made from polyvalent saturated and unsaturated carboxylic acids or their anhydrides and polyhydric saturated and unsaturated amino alcohols, diamines, polyamines and their mixtures recovered, predominantly linear condensates.

Representatives of these compounds to be used according to the invention are, for example, in High Polymers, Vol. XVI, "Polyurethanes, Chemistry and Technology ", written by Saunders-Frisch, Interscience Publishers, New York, London, Volume I, 1962, pp 32 - 42 and pages 44 - 54 and Volume II, 1964, pages 5-6 and 198-199, as well as in the Kunststoff-Handbuch, Volume VII, Vieweg-Höchtlen, Carl-Hanser-Verlag, Munich, 1966, e.g. on pages 45 to 71.

The low molecular weight diols are used in the production of the Polyurethanes to be used according to the invention, e.g. those mentioned above for the production of the polyesters or polycarbonates Connections into consideration.

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Other starting components for the polyurethanes to be used according to the invention are aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates, as described, for example, by W ₀ Siefgen in Justus Liebigs Annalen der Chemie, 562, pages 75 to 136, for example

Ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, cyclobutane-1,3-diisocyanate, cyclohexane-1,3- and 1,4-diisocyanate and any mixtures of these isomers, i -Isocyanato-3,3,5-trimethyl-S-isocyanatomethyl-cyclohexane (DAS 1 202 785), 2,4- and 2,6-hexahydrotolylene diisocyanate and any mixtures of these isomers, hexahydro-1,3 and / or -A , 4-phenylene diisocyanate, perhydro-2,4'- and / or -4,4'-diphenylmethane diisocyanate, 1,3- and 1,4-phenylene diisocyanate, 2,4- and 2,6-tolylene diisocyanate and any mixtures of these isomers, diphenylmethane-2,4'- and / or -4,4'-diisocyanate, naphthylene-1,5-diisocyanate, triphenylmethane-4,4 ', 4 "-triisocyanate, polyphenyl-polymethylene-polyisocyanate, as they are obtained by aniline-formaldehyde condensation and subsequent phosgenation and are described, for example, in British patents 874 430 and 848 671, perchlorinated aryl polyisocyanates, as described, for example, in German Auslegeschrift 1 157 be polyisocyanates containing carbodiimide groups, as described in German patent specification 1,092,007, diisocyanates as described in American patent specification 3,492,330, polyisocyanates containing allophanate groups, as described, for example, in British patent specification 994 890, the Belgian patent specification 761 626 and the published Dutch patent application 7 102 524, polyisocyanates containing isocyanurate groups, as described, for example, in German patents 1 022 789, 1 222 067 and 1 027 394 and in German OffenlegungsSchriften 1 929 034 and 2 004 048, Polyisocyanates containing urethane groups, as described, for example, in Belgian patent specification 752 261 or in American patent specification 3 394 164, polyisocyanates containing acylated urea groups according to German patent specification 1 230 778, Le A 14 972 - 8 - containing biuret groups

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Polyisocyanates, such as those in German Patent 1 101 394, British Patent 889 050 and in French patent 7 017 514 describes polyisocyanates produced by telomerization reactions, as described, for example, in Belgian patent specification 723 640, polyisocyanates containing ester groups, such as e.g. in British patents 956,474 and 1,072,956, in American patent 3,567,763 and in US Pat German file 1 231 688, as well as any mixtures of the above isocyanates.

In addition to the above-mentioned polyurethanes, which are often only soluble in more highly polar solvents such as dimethylformamide or ethyl acetate, so-called "soft-solvent" systems, as described in German patent application P 22 21 756.7, are of particular technical interest. These are essentially linear, segmented, film-forming _{polyurethaneurea elastomers containing practically no free NCO or NH 2} groups and made from NCO prepolymers based on aliphatic and / or cycloaliphatic diisocyanates, optionally additional monomeric diisocyanates of this type and amino-functional, divalent chain extenders in the form of their solution in mixtures of

a) aromatic and / or aliphatic hydrocarbons, which may be chlorinated,

b) aliphatic and / or cycloaliphatic secondary and / or tertiary alcohols.

Non-volatile, aliphatic and / or cycloaliphatic polyisocyanates are then added to the solutions as crosslinkers an NCO functionality of more than 2.0 in weight ratio from about 10: 1 to 1: 1 (based on solids) added.

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The NCO prepolymers are used in a manner known per se from polyols and (cyclo) aliphatic diisocyanates of the above named type manufactured. The preferred chain extenders in this case are (cyclo) aliphatic or araliphatic Diamines, hydrazine or hydrazides. Examples include ethylenediamine, 1,2- or 1,3-propylenediamine, 1,6-hexanediamine, 2-methyl-1,6-hexanediamine, l-methyl-2,4-diamino-cyclohexane, l-amino-3-aminomethyl-3,5 »5-trimethylcyclohexane, 1,3- or 1,4-bis-aminomethyl-cyclohexane, 4,4'-diaminodicyclohexylmethane or similar diamines known per se. Other suitable chain extenders are Hydrazine, methylhydrazine or adipic acid dihydrazide, semicarbazidopropionic acid hydrazide, etc.

Particularly preferred compounds are l-amino-3-aminomethyl-3 > 5 »5-trimethylcyclohexane, 4,4'-diamino-dicyclohexylmethane and ethylenediamine.

Particularly preferred chain extender for prepolymers based on 1-isocyanato-3 / isocyanatomethyl-7 3,5> 5-trimethyl-cyclohexane is 1,4-diaminocyclohexane, there exceptionally high-melting elastomers with high softening and flow temperature provides and in cis / trans stereoisomer mixtures from about 10/90 to 60/40 causes good solubility of the polyurethanes.

The crosslinking agents used in the process according to the invention are preferably low-volatility polyisocyanates, both in monomeric form as well as in di-, tri- or polymerized form or in the form of reaction products.

Examples of such compounds are biuret triisocyanates, which in idealized form after the following reaction accessible are:

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OCN-R-NCO + HpO- ^ OCN-R-NH-CO-NH-R-NCO + C0 _p

+ OCN-R-NCO

N-CO-NH-I
CO-NH-RI

OCN-RN-CO-NH-R-NCO
-NCO

(idealized formula)

R can be an aliphatic radical, for example with 5 to 12 carbon atoms in the chain, or a cycloaliphatic radical Radical, for example a cyclohexane, substituted cyclohexane or dicyclohexylmethane residue. Preference is given to using biuret tri- or polyisocyanates of hexane diisocyanate, of 1-isocyanato-3-isocyanatomethyl-3,5,5-trimethylcyclohexane and of 4,4'-dicyclohexylmethane-d isocyanate. For the process according to the invention, those aliphatic polyisocyanates are also suitable in which some of the isocyanate groups by dimerization and trimerization was converted into uretdione or cyanurate structures. Furthermore, there are addition products with the idealized Oxadiaζintrion structure,

for example

OCN- (CH _{2) 6} -N N- (CH _{2) 6} -NC0 O = C i = 0

suitable, which show a similar mode of action as a triisocyanate because of the ease with which C0 _{2 can be split off.} It is also possible to use reaction products of trihydric and polyhydric alcohols with excess (cyclo) aliphatic diisocyanates in the process according to the invention, for example

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ORIGINAL

the reaction products of trimethylolethane, trimethylolpropane, Glycerine or relatively low molecular weight, polyvalent, branched polyesters or polyethers with molecular weights up to a maximum of 1000 (preferably up to 600) and excess diisocyanates of the structure mentioned «

In addition to the (cyclo) aliphatic polyisocyanates mentioned the aromatic analogues which are particularly readily available industrially can of course also be used, e.g. particularly preferably the addition product of 3 moles of tolylene diisocyanate with 1 mole of trimethylolpropane. One takes However, accept that coatings or coatings with a lower lightfastness than those based on (cyclo) arise aliphatic compounds.

The NCO content of the polyisocyanates to be used according to the invention should be at least 10 percent by weight, preferably 15-40 percent by weight, based on crosslinker solids. The crosslinking polyisocyanates are used in the process according to the invention in an amount of 3 to 18, preferably 3 to 15% by weight, based on polyurethane solids, used.

The application of the coating mixtures made of polyurethane, Crosslinker, catalyst and solvent are carried out by any known procedures, for example by Pouring, squeegeeing, painting, brushing, spraying or printing. In thicker layers and with relatively "soft" Polyurethane settings (low NCO content of the prepolymer used in production, for example 2.5 to 4.5 wt .-% NCO) are textile coatings on for example Nonwovens, woven or knitted fabrics in any design and post-treatment condition (for example, roughened Surfaces). It is also possible to apply them to intermediate carriers, for example release papers, steel strips, etc. possible, whereby the films formed can be further processed by the reversal process.

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Products with a "harder" polyurethane setting (NCO contents of approx. 4 to 7 % in the prepolymer) are preferably used as top coats or finishes for textile coatings, leather or synthetic leather and are applied, for example, by knife coating, spraying or printing.

The acceleration of the reaction brought about by the catalysts used according to the invention has an effect both on the Both direct and reverse coating are extraordinary advantageous. In the first case, the coated substrates can be rolled up quickly without prolonged storage In case of reverse coating, the product can be very quick are lifted off the intermediate carrier, which significantly increases the cost-effectiveness of the coating systems.

The process according to the invention is to be explained in more detail by the following examples. Quantities are, if not noted otherwise than to be understood as parts by weight.

example 1

A 3096 solution of

30 grams of a hydroxyl-terminated polyurethane

(Molecular weight 25,000) from hexanediol adipic acid polyester (molecular weight 2000) and toluene diisocyanate (65% 2-4 and 35 % 2-6 isomer),
2.5 g of a reaction product of 15 parts of trimethylol

propane, 5 parts of butanediol and 80 parts of tolylene diisocyanate;
0 _f 5 g 6-caprolactam / ethylene glycol adduct (molar ratio 1: 1)

in ethyl acetate is applied to a textile with an applicator; the ethyl acetate is then in a drying tunnel or another heating unit suitable for continuous work at temperatures of 90-120 ° C at a

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Throughput speed of 12 m / min, evaporated. To After cooling, the textile can be docked without difficulty. The surface of the coating is dry, the coating is largely cross-linked.

The pot life of the approach is not less than 90 minutes.

Example 2

A 30iX> solution from

30 g of the polyurethane from Example 1, 3 g of the polyisocyanate from Example 1 and 1 g of the adduct of ε-caprolactam and N, N-dimethylethanolamine

in ethyl acetate is applied to a release liner using a roller blade and under the conditions of the example 1 evaporated and chilled. The film formed can easily be lifted off the release carrier without mechanical impairment. The film formed can be provided with an adhesive line in a second operation. Apply to the wet surface a textile laminated. The composite material can easily be lifted off the separating support.

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Claims (1)

Claim Process for the coating and lamination of substrates with solutions of polyurethanes, the bi- or higher functional Containing isocyanates as crosslinking agents and catalysts for the crosslinking reaction, characterized in that that as catalysts associations between lactams and alcohols, thioalcohols, amines, hydrazines, oximes or Water can be used. Le A 14 972 - 15 - 509812/1050