GB2065149A

GB2065149A - Polyurethane Compositions

Info

Publication number: GB2065149A
Application number: GB8033448A
Authority: GB
Original assignee: Carl Freudenberg KG
Current assignee: Carl Freudenberg KG
Priority date: 1979-12-12
Filing date: 1980-10-16
Publication date: 1981-06-24
Also published as: BE882922A; ES497728A0; IT1173701B; FR2471396A1; ES8200384A1; MX153037A; FR2471396B1; IT8048255A0; JPS5682842A; IT8048255A1; BR8003954A; DE2949959A1; SE8004618L; NL8004033A; DE2949959C2

Abstract

A composition comprises a polyurethane and a mould-release compound of one of the formulae [A-(NR-CX-O)a-]m-Y'-[-(O-CX-NR)b-B]n A-(O-CX-NR)a-Y-(NR-CX-O)B-B A-(NR-CX-NR)a-Y-(NR-CX-NR)B-B wherein A, B and each R are independently selected from hydrogen, C1-35 alkyl, C6-14 aryl and substituted aryl, the substituents being halogen, C1-35 alkyl, C6-14 aryl, C1-35 alkylthio, C6-14 arylthio or C7-15 aralkyl, provided that at least one of A, B and R is not hydrogen; X is oxygen or sulphur; Y is C1-35 alkylene, C6-14 arylene, C7-30 aralkylene, -(CH2)1-4-O-(CH2)1-4-, -(CH2)1-4-S-(CH2)1-4-, or a polyester, polyether, polycarbonate or polybutadiene having a molecular weight of 400 to 4000; Y' is Y or a valence bond; m and n are independently selected from 1, 2 and 3; and one of a and b is an integer and the other is zero or the same or a different integer.

Description

SPECIFICATION Urethan Compositions Polyurethanes are widely used, in particular for producing shaped parts by reaction of suitable constituents in a mould. The constituents can be introduced into the moulds by pouring and are hardened therein. Polyurethane elastomers are also often extruded and/or subjected to thermoplastic shaping. Shaped parts of many kinds can be produced, for example, by injection moulding, extrusion or hollow-body blowing.

In almost all these methods, the problem arises in using polyurethanes that it is necessary to employ a release compound, to avoid adhesion of the shaped part to the mould wall. To this end, the moulds are often provided with a thin film of a release compound before the polyurethane composition is fed in. Usually, waxes, soaps or oils are employed. These so-called "external" release compounds can be used satisfactorily, but they must be applied in an operation separate from the hardening reaction.

During this time, the tool is not in production. Exact apportionment or quantitative regulation of the release compound is often difficult when applied by spraying or brushing and, in the case of complicated shapes, for example where there are fine engravings on the tool, the compound does not fill the mould completely.

Because of these difficulties, "internal" parting compounds (which usually comprise fatty acid derivatives) have been developed. A suitable fatty acid derivative may be added to the polyurethane composition, usually in quite a large amount, and this can ensure that the part to be produced can be neatly removed from the tool. The practicability of such internal parting compounds in the automatic production of shaped parts is limited, however, inasmuch as, after repeated cycles, fouling of the tool occurs and, consequently, interruption of the automatic process is necessary and, moreover, the mechanical properties of the shaped or moulded parts produced are affected by the relatively high amounts of the mould-release compound. Such internal parting compounds for polyurethanes are described, for example, in German Offenlegungsschriften 23 07 589 and 23 19 648.

A polyurethane composition according to the invention comprises a mixture of a suitable high molecular weight urethane polymer with a small amount of at least one urethane- and/or urea-based oligomeric product of one of the following formulae, as a mould-release compound: [A-(NR-CX-O)a-]-Y'-[-(O-CX-NR)b-B]n A-(0-CX-NR)6-Y-(NR-CX-0) bB A(NRCXNR)aY(NRCXNR)bB In the above formulae, A, B and each R are selected independently from hydrogen, Cm1-35 alkyl, C6~14 aryl and substituted aryl the substituents being halogen atoms, C1~35 alkyl, C6~14 aryl, C1~35 alkylthio C~14 arylthio or C7~,5 aralkyl; X is oxygen or sulphur;Y' is C1~35 alkylene, C6~14 arylene, C,,, alkarylene, C72o aralkylene, -(CH2) 14-0-(CH2)14- or -(CH2) 14-S-(CH2)14- or a polyester, polyether, polycarbonate or polybutadiene having a molecular weight of 400 to 4000; Y' is Y or a valence bond; m and n are independently selected from 1, 2 and 3; and one of a and b is an integer and the other is zero or the same or a different integer.

The oligomeric product is preferably used in an amount of 0.01 to 10.0, and more preferably 0.1 to 1.5, parts by weight per 100 parts by weight of the high molecular weight urethane polymer.

Starting constituents for the high molecular weight polyurethane compositions are aliphatic, cycloaliphatic, araliphatic, aromatic and heterocyclic polyisocyanates, such as are described, for example, by W. Siefken in Justus Liebig's Annalen der Chemie, 562, pages 75-136. Examples are ethylene diisocyanate, 1 ,4-tetramethylenediisocyanate, 1 ,6-hexamethylenediisocyanate, 1,12- dodecanediisocyanate, cyclobutane-l ,3-diisocyanate, cyclohexane-l 1,3-diisocyanate, cyclohexane-1,4- diisocyanate and also any desired mixtures of these isomers,1-isocyanato-3,3,5-trimethyl-5- isocyanatomethylcyclohexane (German Offenlegungsschrift 12 02 785 and U.S.Patent Specification No.3,401,190), and 2,6-hexahydrotolylenediisocyanate and also any desired mixtures of these isomers, hexahydro-1,3- and/or -1 ,4-phenylenediisocyanate, perhydro-2,4'- and/or -4,4'- diphenylmethanediisocyanate, 1,3- and 1,4-phenylenediisocyanate,2,4- and 2,6-tolylenediisocyanate and also any desired mixtures of these isomers, diphenylmethane-2,4'- and/or -4,4'-diisocyanate, naphthylene- 1 ,5-diisocyanate, triphenylmethane-4,4',4"-triisocyanate, polyphenyl polymethylene polyisocyanates (as obtained by aniline-formaldehyde condensation and subsequent phosgenation and, for example, described in British Patent Specifications Nos. 874,430 and 848,671), m and pisocyanatophenylsuiphonyl isocyanates (U.S. Patent Specification No. 3,277,138), polyisocyanates having carbodiimide groups (U.S. Patent Specification No. 3,152,162), diisocyanates as described in U.S. Patent Specification No. 3,492,330, polyisocyanates having allophanate groups (British Patent Specification No. 994,890, Belgian Patent Specification No. 761,626 and the published Dutch Patent Application No. 7102524), polyisocyanates having isocyanurate groups (U.S. Patent Specification No.

3,001,973, German Patent Specifications Nos. 1,022,789, 1,222,067 and 1,027,394 and German Offenlegungsschriften 1 9 29 034 and 20 04 048), polyisocyanates containing urethane groups (Belgian Patent Specification No. 752,261 or U.S. Patent Specification No. 3,394,164), acylated urea group-containing polyisocyanates (German Patent Specification No. 1,230,778), polyisocyanates having biuret groups (U.S. Patent Specifications Nos. 3,124,605 and 3,201,372 and British Patent Specification No. 889,050), polyisocyanates prepared by telomerisation reactions (U.S. Patent Specification No. 3,654,106), polyisocyanates having ester groups (British Patent Specifications Nos.

965,474 and 1,072,956, U.S. Patent Specification No. 3,567,763 and German Patent Specification No. 1,232,688), reaction products of the above-mentioned isocyanates with acetals (German Patent Specification No. 1,072,385), and polymeric fatty acid radical containing polyisocyanates (U.S. Patent Specification No. 3,455,883).

It is also possible to use the distillation residues obtained in commercial isocyanate preparation and which have isocyanate groups, these distillation residues being dissolved, if necessary or desired, in one or more of the above-mentioned polyisocyanates. Moreover, it is possible to employ any desired mixtures of the above-mentioned polyisocyanates.

Particularly preferred as a rule are the commercially available polyisocyanates, for example toluene 2,4- and 2,6-diisocyanate and any desired mixtures of these isomers ("TDls"), polyphenyl polymethylene polyisocyanates, as prepared by anilineformaldehyde condensation and subsequent phosgenation ("crude MDI"), and polyisocyanates having carbodiimide groups, urethane groups, allophanate groups, isocyanurate groups, urea groups or biuret groups ("modified polyisocyanates").

Further starting constituents which can be used in the invention are compounds with at least two hydrogen atoms which are reactive towards isocyanates and, preferably, having a molecule weight of 400 to 10,000. Such compounds may contain amino groups, thiol groups or carboxyl groups, but are preferably polyhydroxyl compounds. Suitable polyhydroxy compounds have at least two, e.g. two to eight, and preferably two to four, hydroxyl groups. Their preferred molecular weight is from 800 to 10,000, more preferably 1000 to 6000. They may be, for example, polyesters, polyethers, polythioethers, polyacetals, polycarbonates or polyester amides which are known per se for producing homogeneous and cellular polyurethanes.

Suitable polyesters are, for example, reaction products of polyhydric, preferably dihydric or trihydric, alcohols with polycarboxylic, preferably dicarboxylic, acids. Instead of a free polycarboxylic acid, it is also possible to employ the corresponding polycarboxylic acid anhydride or corresponding polycarboxylic acid ester with a lower alcohol, or a mixture thereof, to prepare the polyesters. The polycarboxylic acids may be of an aliphatic, cycloaliphatic, aromatic and/or heterocyclic nature and may, if necessary or desired, be substituted, for example by halogen atoms, and/or unsaturated.

Examples of such compounds for forming suitable polyesters are succinic acid, adipic acid, suberic acid, azelaic acid, sebacic acid, phthalic acid, isophthalic acid, trimellitic acid, phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride, tetrachlorophthalic anhydride, endomethylenetetrahydrophthalic anhydride, glutaric anhydride, maleic acid, maleic anhydride, fumaric acid, dimeric and trimeric fatty acids such as oleic acid, mixed, if desired, with monomeric fatty acids, terephthalic acid dimethyl ester and terephthalic acid bis-glycol ester.Suitable polyhydric alcohols include ethylene glycol, propylene glycol, trimethylene glycol, 1,4- and 2,3-butylene glycol, hexamethylene glycol, 1 ,8-octanediol, neopentyl glycol, 1 ,4-bis(hydroxymethyl)cyclohexane, 2-methyl- 1 3-propanediol, glycerol, trimethylolpropane, 1 ,2,6-hexanetriol,1 ,2,4-butanetriol, trimethylolethane, pentaerythritol, quinitol, mannitol, sorbitol, methyl glucoside, diethylene glycol, triethyiene glycol, tetraethylene glycol, polyethylene glycols, dipropylene glycol, polypropylene glycols, dibutylene glycol and polybutylene glycols. The polyesters may have terminal carboxyl groups in proportion.Polyesters from lactones, for example -caprolactone, or from hydroxycarboxylic acids, for example cs- hydroxycaproic acid, can also be used.

Polyethers which may be used in the invention have at least two, usually two to eight, and preferably two or three, hydroxyl groups. Such compounds are known per se and may be prepared, for example, by homopolymerization of epoxides such as ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide or epichlorhydrin, for example in the presence of BF3. Alternatively such epoxides may be reacted with compounds with reactive hydrogen atoms, such as water, alcohols, ammonia or amines, for example ethylene glycol, propylene glycol, trimethylene glycol, trimethylolpropane, 4,4'-dihydroxydiphenylpropane, aniline, ethanolamine or ethylenediamine.

Sucrose polyethers, as described, for example, in German Offenlegungsschriften 11 76 358 and 10 64 938, are also suitable. Often, polyethers which predominantly comprise primary OH groups (up to 90% by weight, referred to all the OH groups present in the polyether) are preferred. Polyethers modified by vinyl polymers, as produced, for example, by polymerization of styrene and acrylonitrile in the presence of polyethers (see U.S. Patent Specifications Nos. 3,383,351; 3,304,273; 3,523,093 and 3,110,695, and German Patent Specification No. 1,152,536), and polybutadienes having OH groups, are also suitable.

Polythioethers which can be used in the invention include the condensation products of thiodiglycol alone or with other glycols, dicarboxylic acids, formaldehyde, aminocarboxylic acids or aminoalcohols. Depending on the constituents, the products are mixed polythioethers, polythioether esters or polythioether ester amides.

Polyacetals which can be used in the invention include compounds which can be prepared from glycols, such as diethylene glycol, triethylene glycol, 4,4'-dioxethoxydiphenyldimethylmethane, hexanediols and formaldehyde. Suitable polyacetals can also be prepared by polymerization of cyclic acetals.

Polycarbonates having hydroxyl groups which can be used in the invention include those known per se and which can be prepared by reacting diols such as trimethylene giycol, 1.4-butanediol, 1,6- hexanediol, diethylene glycol, triethylene glycol or tetraethylene glycol with diaryl carbonates, e.g.

diphenyl carbonate, or phosgene.

Polyester amides and polyamides which can be used in the invention include the predominantly linear condensates which are obtained from polyvalent saturated and unsaturated carboxylic acids or their anhydrides and polyvalent saturated and unsaturated aminoalcohols, diamines or polyamines, or mixtures thereof.

Representative compounds which can be used in the invention are described, for example, in High Polymers, Vol. XVI, "Polyurethanes, Chemistry and Technology", by Saunders-Frisch, Interscience Publishers, New York, London, Volume 1, 1962, pages 32-42 and pages 44-54, and Volume II, 1964, pages 5-6 and 198-199, and also in the Kuntstoff-Handbuch (Plastics Handbook), Volume VII, Vieweg-Höchtlen, Carl-Hanser-Verlag, Munich, 1966, e.g. on pages 45-71.

Of course, mixtures of the above-mentioned compounds with at least two hydrogen atoms which are reactive towards isocyanates and having a molecular weight of 400 to 10,000 can be used, for example mixtures of polyethers and polyesters.

Compounds with at least two hydrogen atoms which are reactive towards isocyanates and having a molecular weight of 32 to 400 can also be used as starting constituents in the invention. Such compounds, having thiol, carboxyl, or, preferably, hydroxyl or amino groups, serve as chain-lengthening agents or cross-linking agents. As a rule, these compounds have two to eight, and preferably two or three, reactive hydrogen atoms. Of course, mixtures of such compounds can be employed.

Examples of these lower molecular weight compounds are ethylene glycol, propylene glycol, trimethylene glycol, 1 ,4- or 2,3-butylene glycol, 1 ,5-pentanediol, hexamethylene glycol, 1,8- octanediol, neopentyl glycol, 1 ,4-bis(hydroxymethyl)cyclo hexane, 2-methyl-1 ,3-propanediol, glycerol, trimethylolpropane, 1,2,6-hexanetriol, trimethylolethane, pentaerythritol, quinitol, mannitol, sorbitol, diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycols having a molecular weight of up to 400, dipropylene glycol, polypropylene glycols having a molecular weight of up to 400, dibutylene glycol, polybutylene glycols having a molecular weight of up to 400, castor oil, 4,4'- dihydroxydiphenylpropane, dihydroxymethylhydroquinone, 1 ,4-p henylene-bis( & yd roxyethyl ether), ethanolamine, N-methylethanolamine, diethanolamine, N-methyldiethanolamine, triethanolamine, 3aminopropanol and ester diols of the formulae HO-(CH,),-CO-O-(CH,),-OH and HO-(CH,),-O-CO-O-CO-O-(CH,),-OH in which Q is C210, preferably C26, alkylene, x is from 2 to 6 and y is 3, 4 or 5. Examples of such ester diols are -hydroxybutyl-E-hydroxycaproic acid ester, w-hydrnxyhexyl-y-hydrnxybutyric acid ester, adipic ester bis(P-hydroxyethyl) ester and terephthalic acid bis(,B-hydroxyethyl) ester.

Compounds such as 1-mercapto-3-aminopropane, substituted aminoacids such as glycine, alanine, valine, serine or lysine, and substituted dicarboxylic acids such as succinic acid, adipic acid, phthalic acid, 4-hydroxyphthalic acid or 4-aminophthalic acid, may also be employed as chainlengthening agents.

Compounds which are monofunctional with respect to isocyanates may be employed as so-called "chain terminators", e.g. in proportions of 0.01 to 10% by weight based on the solid polyurethane matter. Such monofunctional compounds are, for example, monoamines such as butylamine, dibutylamine, octylamine, stearylamine, N-methylstearylamine, pyrrolidine, piperidine or cyclohexylamine, and monohydric alcohols such as butanol, 2-ethylhexanol, octanol, dodecanol, amyl alcohols, cyclohexanol or ethylene glycol monoethyl ether.

In the invention, it is also possible to use polyhydroxy compounds in which high molecular weight polyadducts or polycondensates are contained in finely dispersed or dissolved form. Such modified polyhydroxy compounds are obtained when polyaddition reactions (e.g. reactions between polyisocyanates and aminofunctional compounds) Cr polycondensation reactions (e.g. between formaldehyde and phenols and/or amines) are allowed to take place in situ in the above-mentioned compounds having hydroxyl groups. Such processes are described, for example, in German Auslegeschriften 11 68 075 and 12 60 142 and in German Offenlegungsschriften 23 24 134, 24 23 984,25 12 385,25 13 815,25 50 796,25 50 797,25 50 833 and 25 50 862. It is also possible, as described in U.S.Patent Specification No. 3,869,413 or German Offenlegungsschrift 25 50 860, to mix a ready-prepared aqueous polymer dispersion with a polyhydroxy compound and thereafter remove the water from the mixture. When such modified polyhydroxy compounds are used, it is often possible to obtain polyurethane plastics having especially good mechanical properties.

The oligomeric urethanes or ureas may be prepared in a manner known per se. They are products of the reaction of monofunctional isocyanates with mono- or poiyfunctional alcohols and/or amines.

Examples of particularly preferred substances are, for example, reaction products of monoisocyanates, e.g. with 6 to 18 carbon atoms, for example stearyl isocyanate and/or palmitin isocyanate, with monohydric alcohols, e.g. with 6 to 18 carbon atoms, for example stearyl alcohol or palmitin alcohol. Unsaturated alcohols such as oleyl alcohol can also be used. Reaction products of monoisocyanates and monoamines with 6 to 18 carbon atoms are also suitable.

Alternatively, the mould-release compound may be a reaction product of a monoisocyanate and a polyhydric alcohol. Suitable polyhydric alcohols include ethylene glycol, propylene glycol, trimethylene glycol, 1 4-butylene glycol, 2,3-butylene glycol, 1 ,5-pentanediol, hexamethylene glycol, 1,12- dodecanediol, hydroquinone bis(hydroxyethyl) ether, glycerin, trimethylolpropane, hexanetriol and pentaerythritol. Polyethylene glycols with a molecular weight of 100 to 4000, and polyhydroxy compounds with a molecular weight between 650 and 6000, for example polyesters, polyethers, polyester amides, polyacetals, polycarbonates and polycaprolactones having hydroxyl groups and silicones having hydroxyl groups, are also suitable.

Mixtures of alcohols and mixtures of the oligomeric urethanes can be used, if desired.

It is often preferred to use, in the invention, polyamines such as, for example, ethylenediamine, 1 6-hexanediamine, 1 4-butylenediamine, 1,1 1-undecylenediamine, 2,4- and 2,6hexahydrotoluenediamine, mixtures of the above substances, 4,4'-diaminodiphenylmethane, pxylylenediamine, hydrazine, substituted hydrazines, 3-amino-1 -methylaminopropane or dipropylenetriamine, as starting materials.

In the invention, it is proposed that reaction products of polyisocyanates and the above-described monohydric alcohols and monoamines should be used. Particularly preferred in this instance are the commercially available isocyanates such as, for example, hexamethylenediisocyanate, 4,4'- diphenylmethanediisocyanate, modified 4,4'-diphenylmethanediisocyanates, toluene 2,4- and 2,6diisocyanate and mixtures of these substances, and fatty acid diisocyanates.

The oligomeric urethanes and ureas which, in use of compositions of the invention, can act as internal mould-release compounds are then used completely and incompletely by conventional methods of preparation. The compounds are incorporated in the high molecular weight polyurethane composition in any desired manner. A method which has proved particularly satisfactory comprises dissolving or dispersing the mould-release compound in the starting compounds for the high molecular weight polyurethane compositions. If this is not desired or not possible, then it may be worked in during plasticizing or working-up, thermoplastically, the polyurethane composition.

The following Examples illustrate the invention. All parts and percentages are by weight, unless otherwise indicated.

Examples 1 to 20 describe the preparation of oligomeric urethanes, and the general method is equally applicable to oligomeric ureas and thiourethanes. The mono- or polyisocyanate and the compound containing active hydrogen are mixed together and heated, suitably to 1300 C. After a reaction time of about 30 minutes, the product is poured onto a cold plate and allowed to solidify. After comminution, the reaction product can then be used immediately.

Examples 1 to 10 1 mole of a reactive hydrogen compound is reacted with 2 moles of a 65:30 mixture of stearyl and palmityl isocyanates. The former compounds and the melting points of the products are shown in Table I: Table I Reactive Example Compound m.p. (0C) 1 ethylene glycol 99.5 2 trimethylene glycol 94 3 1 ,4-butylene glycol 103 4 2,3-butylene glycol 106 5 neopentyl glycol 59 6 hexamethylene glycol 11 7 7 1,12-dodecanediol 102 8 diethylene glycol 93 9 thiodiglycol 81 10 59:45::hexamethylene 98 glycol: 1 ,4-butylene glycol Examples 11 to 13 2 moles stearyl alcohol are reacted with 1 mole of, respectively, hexane-1 ,6-diisocyanate, 4,4'- diisocyanatodiphenylmethane and toluene-2,4-diisocyanate. The melting points of the products are 126, 142 and 970C.

Examples 14 to 17 1 mole of, respectively, stearyl alcohol, 2-ethylhexanol, oleyl alcohol and trimethylolpropane, is reacted with 1 mole stearyl isocyanate. The melting points of the products are 75, 63,25 and 41 OC.

Examples 18 and 19 1 mole of, respectively, trimethylolpropane and 2-butene-1,4-diol, is reacted with 2 moles stearyl isocyanate. The melting points of the products are 52 and 920C.

Example 20 602 parts of a polybutadienol having an OH number of 46.6 and molecular weight of 2800 are Example 21 1000 parts by weight of a polyester obtained from adipic acid and a mixture of ethylene glycol and butanediol (1:1) and 20 parts by weight of the compound of Example 3 are heated to 1 200C in a vessel equipped with a stirrer. After removal of water for one hour in vacuo, 850 parts by weight of MDI (4,4'-diisocyanodiphenylmethane) are added. The mixture is stirred for 30 minutes. After this time, 240 parts by weight of butanediol are added within 30 seconds while stirring is continued and the reaction product is poured out onto a plate preheated to 11 00C and left for one hour at this temperature.

After the polyurethane has cooled down, it is granulated and injection-moulded on a commercial screw-type injection moulding machine to form test sheets. The test sheets are tempered for 12 hours at 1 100C.

Example 22 (Comparative) The procedure of Example 21 is repeated without using the parting compound.

Example 23 Under the conditions described in Example 1, 1000 parts by weight of polycaprolactone (m.w.

2000), 600 parts by weight of MDI, 1 59 parts by weight of butanediol and 20 parts by weight of the parting compound of Example 6 are used as starting materials.

Example 24 (Comparative) The procedure of Example 23 is repeated, but without the parting compound.

Table II gives the mechanical properties of the products of Examples 21 to 24.

Table II Rebound Tensile Elongation Abrasion Example Hardness Elasticity strength (N/mm2) at break {%J (mm3) 21 96 30 37 467 25 22 95 29 36 480 28 23 95 33 29 501 15 24 90 34 27 490 18 It'can be seen that the properties of polyurethanes need not be affected by the use of release compounds as defined for use in the invention.

Example 25 to 29 The procedure of Example 23 is repeated but using, as release compound, the products of Examples 13, 14, 16, 18 and 20, respectively.

Examples 23 to 29 were examined by producing shaped parts on a conventional injection moulding machine. The tool is equipped with an automatic ejector system. The parting effect can be judged by observing the cycles of removal from the moulds with the various polyurethane compositions. When using an optimum parting compound, the mixture can always be removed from the mould.

It was possible to break the test off for each of Examples 23 and 25 to 29 after 200 cycles; further tests after so large a number of cycles of removal from the mould did not change the test results. The product of Example 24 gave only five removal cycles. It was necessary then to use an external parting compound.

Claims

1. A composition comprising a urethane and a mould-release compound of one of the formulae [A-(NR-CX-O)a]m Y'-[-(O-CX-NR)b-B]n A--(OO-CCX-N R)8-Y-( N R-CX-O) bB A(NRCXNR)aY(NRCXNR)bB wherein A, B and each R are independently selected from hydrogen, C1~35 alkyl, Cm~14 aryl and substituted aryl, the substituents being halogen, C1~35 alkyl, C6~,4 aryl, C1~35 alkylthio, C~14 a rylthio or C7is aralkyl, provided that at least one of A, B and R is not hydrogen; X is oxygen or sulphur;Y is C1~35 alkylene, Cm~14 arylene, C,~30 aralkylene, -(CH2)1-O-(CH2)14-, -(CH2)14-S-(CH2)1 -, or a polyester, polyether, polycarbonate or polybutadiene having a molecular weight of 400 to 4000; Y' is Y or a valence bond; m and n are independently selected from 1, 2 and 3; and one of a and b is an integer and the other is zero or the same or a different integer.

2. A composition according to Claim 1 in which the mould-release compound is 1,6hexanedistearyl diurethane, distearyl urethane or oleyl stearyl.

3. A composition according to Claim 2 in which the mould-release compound is 1,6hexanedistearyl diurethane.

4. A composition according to Claim 1 in which the mould-release compound is the reaction product of 2 moles stearyl alcohol and 1 mole toluene diisocyanate.

5. A composition according to Claim 1 in which the mould-release compound is the reaction product of 1 mole trimethylolpropane and 1 mole stearyl isocyanate.

6. A composition according to Claim 1 in which the mould-release compound is the reaction product of 1 mole trimethylolpropane and 2 moles stearyl isocyanate.

7. A composition according to Claim 1 in which the mould-release compound is the reaction product of 1 mole polybutanediol having a functionality of 2.3 and 2 moles stearyl isocyanate.

8. A composition according to any preceding claim which comprises from 0.01 to 10 parts by weight of the mould-release compound per 100 parts by weight of the urethane.

9. A composition according to Claim 8 which comprises 0.1 to 1.5 parts by weight of the mouldrelease compound per 100 parts by weight of the urethane.

10. A composition according to Claim 1 substantially as described in any of Examples 21,23 and 25to29.