(19) TZZ_¥ _T

(11) EP 1 732 965 B1

(12) EUROPEAN PATENT SPECIFICATION

(45) Date of publication and mention (51) Int Cl.: of the grant of the patent: C01F 7/00 (2006.01) C08J 3/00 (2006.01) 26.02.2014 Bulletin 2014/09 (86) International application number: (21) Application number: 04821623.8 PCT/US2004/022759

(22) Date of filing: 14.07.2004 (87) International publication number: WO 2005/089085 (29.09.2005 Gazette 2005/39)

(54) IMPROVED COLOR STABILITY OF ISOCYANATES VERBESSERTE FARBSTABILITÄT VON ISOCYANATEN AMELIORATION DE LA SOLIDITE DE LA COULEUR DES ISOCYANATES

(84) Designated Contracting States: • VARRON, Corinne AT BE BG CH CY CZ DE DK EE ES FI FR GB GR F-69003 Lyon (FR) HU IE IT LI LU MC NL PL PT RO SE SI SK TR (74) Representative: Gillard, Richard Edward et al (30) Priority: 14.07.2003 US 487177 P Elkington and Fife LLP Thavies Inn House (43) Date of publication of application: 3-4 Holborn Circus 20.12.2006 Bulletin 2006/51 London EC1N 2HA (GB)

(73) Proprietor: Vencorex US, Inc. (56) References cited: Freeport, TX 77541 (US) EP-A- 0 210 859 EP-A- 0 425 710 EP-A- 0 735 027 WO-A-94/19385 (72) Inventors: WO-A-98/14492 DE-A1- 1 802 659 • ROSEN, Richard GB-A- 923 190 GB-A- 1 102 387 Princeton, NJ 08540 (US) GB-A- 2 184 733 US-A- 3 069 369 • BERNARD, Jean-Marie US-A- 3 115 465 US-A- 4 305 839 F-69440 Saint-Laurent D’agny (FR) US-A- 4 576 855 US-A- 5 719 229 • WO, Shiming US-A- 6 043 332 US-A1- 2002 115 782 Monroe Township NJ08831 (US)

Note: Within nine months of the publication of the mention of the grant of the European patent in the European Patent Bulletin, any person may give notice to the European Patent Office of opposition to that patent, in accordance with the Implementing Regulations. Notice of opposition shall not be deemed to have been filed until the opposition fee has been paid. (Art. 99(1) European Patent Convention). EP 1 732 965 B1

Printed by Jouve, 75001 PARIS (FR) EP 1 732 965 B1

Description

FIELD OF THE INVENTION

5 [0001] This invention relates to color stabilizing compositions, and more particularly to color stabilizing compositions useful for stabilizing the color of isocyanates, particularly polyisocyanate oligomers and prepolymers, to be used to prepare polyurethane coatings, films therefrom. The polyisocyanates can also be used to form adhesives, sealants and elastomers.

10 BACKGROUND OF THE INVENTION

[0002] Two component thermosetting polyurethanes are widely used in protective coatings or films in a broad range of applications, such as for example, coatings for automotive machinery, equipment, and other surfaces in need of a protective coating. These room temperature- curable polyurethanes are prepared from polyisocyanates and a component 15 containing an active hydrogen compound, such as a polyol or an amine. [0003] Two-component polyurethane coating systems include a polyisocyanate component that reacts with a polyol component that comprises, for example, an acrylic polyol or polyester polyol, to form useful films. The system also includes organic solvents, and a variety of adjuvant components, e.g., surface active agents, pigments, dispersants, diluents, and fillers. This type of coating is one of the finest coatings available that can be produced without the applicatio n 20 of heat or other external sources of energy. They are very useful for objects that cannot be heat-cured, such as large machinery, airplanes, ships and vehicles. [0004] In some embodiments, two component polyurethane compositions are cured at elevated temperature. It has been recognized that such systems tend to discolor at elevated temperatures and prior art methods to stabilize the color of such polyurethanes systems have been developed. The approach of these methods is either purification or stabilization 25 of the polyisocyanate. For example, U.S. 4,297, 472 teaches adding a small amount of vicinal diols to the formulation to improve the color stability of the polyurethanes. U.S. 4,065, 362 teaches a process to purify the organic isocyanate, U.S. 3,715, 381 teaches incorporating 2,4-di (t-butyl)-p-cresol (BHT) in the formulation, and U.S. 2,957, 903 teaches incorporating an amount of triaryl phosphite in a polyisocyanate. U.S. 4,677, 154 relates to elimination of discoloration in polyurethanes, particularly thermoplastic polyurethanes, by the addition to the reaction mixture from 0.01 to 1 percent 30 by weight, based on the isocyanate component, a stabilizer package characterized as BHT and a compound selected from a specific group of compounds which includes tris (nonylphenyl) phosphite, distearyl thiodipropionate, triisodecyl phosphite, trilauryl trithiophosphite, and blends thereof. [0005] EP 0 425 710 discloses a process for producing a modified organic polyisocyanate having an isocyanurate ring. EP 0 210 859 relates to curable compositions for use as adhesives, coatings and sealants. WO 98/14492 discloses 35 a process for the production of micro- cellular or non- cellular, light-stable elastomeric, flexible or semiflexible polyurethane mouldings. US 5,719,229 relates to solid elastomeric polyurethanes. US 6,043,332 relates to a process for the production of polyisocyanates containing uretdione groups. EP 0 735 027 discloses a process for the preparation of (cyclo) aliphatic uretdiones. GB1102387 relates to stabilized isocyanate- ether solutions. US2002115782 discloses a thermoplastic mold- ing composition comprising a polyurethane elastomer. DE1802659 relates to vinyl fluoride polymers. US 3,069,369 40 relates to colour stabilised polyethylene compounds. GB923190 relates to antioxidant compositions. US 3,115,465 discloses compositions comprising phosphite esters and a methylene bis- phenol. US4,305,839 discloses thestabilisation of impurehydroxybenzophenones by the addition of an organic phosphiteor organic phosphonite. WO94/19385 discloses a process for the polymerization of cyclo-olefins. [0006] Other two component polyurethane systems are curable at relatively mild temperatures in the presence of a 45 catalyst for promoting reaction of the polyisocyanate with the polyol. In one embodiment of such low temperature curing two component polyurethane coating systems, the catalyst is included in the polyisocyanate component of the system to form a "hardener" component that is subsequently combined with the polyol component to form a curable coating composition. However, it has been found that including the catalyst in the polyisocyanate component of such systems markedly increases the potential for undesirable discoloration of the polyisocyanate and related coating and despite the 50 known color stabilizing methods, it has been found that a need exists for a stabilizer that will efficiently stabilize the colo r of a solution of an isocyanate in the presence of a catalyst for the reaction of the isocyanate with an active hydrogen compound.

SUMMARY OF THE INVENTION 55 [0007] It has been discovered in accordance with this invention that color of isocyanates can be stabilized by admixing with the isocyanate a color stabilizing effective amount of a stabilizer comprised of a trialkyl phosphite component, each alkyl group of said trialkyl phosphite component having less than 10 carbon atoms. Typically, the stabilizer is a system

2 EP 1 732 965 B1

which will also further comprise a phenolic antioxidant component (e. g. a t- butylated hydroxytoluene selected from the group consisting of 2,6ditertiarybutyl hydroxytoluene and 2-tertiarybutyl hydroxytoluene). [0008] In a first aspect, the present invention is directed to a hardener composition for use as the first component of a two component polyurethane coating composition, comprising: 5 one or more aliphatic polyisocyanate oligomers selected from a polyisocyanate dimer, a polyisocyanate trimer, a product of condensation of two or more polyisocyanate dimers, a product of condensation of two or more polyiso- cyanate trimers, or a condensation product of dimers with trimers, derived from isophorone diisocyanate, ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, decamethylene diisocyanate, or nor- 10 bornene diisocyanate, a catalyst for promoting reaction of the polyisocyanate with a reactive hydrogen compound,

a first antioxidant comprising one or more of sterically hindered phenol antioxidants and secondary aryl amine antioxidants, and 15 a second antioxidant comprising one or more organophosphite antioxidants according to the formula:

(RO)3P

wherein each R is independently alkyl or aryl. 20 [0009] In a second aspect, the present invention is directed to a polyisocyanate formulation suitable for use in preparing polyurethanes therefrom in which the color stabilizing effective amount of the stabilizer system trialkyl phosphite com- ponent, each alkyl group of said trialkyl phosphite component having less than 10 carbon atoms, comprises from 0.1 to 2.0 weight % based on the total weight of the polyisocyanate formulation. 25 [0010] In a third aspect, the present invention provides a color stabilized isocyanate composition for use in a formulation for preparing polyurethanes therefrom, the color stabilized isocyanate composition comprising:

(a) a phenolic antioxidant, e.g. a t- butylated hydroxytoluene selected from the group consisting of 2,6- ditertiarybutyl hydroxytoluene and 2-tertiarybutyl hydroxytoluene, 30 (b) a trialkyl phosphite component, each alkyl group of said trialkyl phosphite component having less than 10 carbon atoms and

(c) at least one isocyanate. 35 [0011] Ina fourth aspect, the presentinvention is directed toa method for making a color stabilizedhardener composition for use as a component of a polyurethane coating composition, comprising combining a polyisocyanate, a catalyst for promoting reaction of the polyisocyanate with a reactive hydrogen compound, and one or more antioxidants selected from:

40 a first antioxidant comprising one or more of sterically hindered phenol antioxidants and secondary aryl amine antioxidants, and a second antioxidant comprising one or more organophosphite antioxidants.

[0012] In a fifth aspect, the present invention is directed to a method for stabilizing the color of a hardener composition 45 for use as a component of a polyurethane coating composition, said hardener composition comprising a polyisocyanate and a catalyst for promoting reaction of the polyisocyanate with a reactive hydrogen compound, comprising adding to the hardener composition a color stabilizing amount of one or more antioxidants selected from:

a first antioxidant comprising one or more of sterically hindered phenol antioxidants and secondary aryl amine 50 antioxidants, and a second antioxidant comprising one or more organophosphite antioxidants.

[0013] By this invention, the shelf life of the isocyanate is improved.

55 DETAILED DESCRIPTION OF THE INVENTION

[0014] Suitable sterically hindered phenols antioxidants include those hindered phenols that are commercially available as antioxidants, for example, under the IONOL or IONOX trade names from Laporte Performance Chemicals, South-

3 EP 1 732 965 B1

ampton, UK, such as 2,4-dimethyl-6-butylphenol, 4,4’-methylene-bis(2,6-di-tert-butylphenol), and 2,6-di-tert.butyl-N- N’dimethylamino-p-cresol, butylated hydroxyanisole, 2,6-di-tertbutylphenol, 2,4,6-tri-tertbutylphenol, 2-tert-butylphenol, 2,6-diisopropylphenol, 2-methyl-6-tert-butylphenol, 2,4-dimethyl-6-tertbutylphenol, 4-(N,N-dimethylaminomethyl)-2,8- di-tertbutylphenol, 4-ethyl-2,6-di-tertbutylphenol. 5 [0015] Suitable secondary aryl amine antioxidants include those secondary amines known for use as antioxidants, such as, for example, diphenylamine, alkyl diphenylamines, phenylnaphthylamines, and alkylphenylnaphthylamines. [0016] In one embodiment, the first antioxidant comprises 2,6- ditertiarybutyl-4-methylphenol, also known as butylated hydroxy toluene or "BHT". [0017] Suitable organophosphite antioxidants include those organophosphites known for use as antioxidants. In one 10 embodiment, the organophosphite comprises one or more compounds according to the formula:

(RO)3P

wherein each R is independently alkyl or aryl. 15 [0018] As used herein, the term "alkyl" refers to a radical of a saturated aliphatic group, including straight chain alkyl groups, branched chain alkyl groups, and cycloalkyl groups, wherein such straight and branched chain alkyl groups may each be optionally substituted with cycloalkyl, such cycloalkyl groups may optionally be substituted with straight or branched chain alkyl, and such straight chain alkyl, branched chain alkyl, and cycloalkyl groups may each be optionally be substituted with aryl, and includes, for example, methyl, ethyl, isopropyl, t- butyl, isodecyl, stearyl, icosyl, cyclohexyl, 20 phenylmethyl. [0019] As used herein, the term "aryl" as used herein means a compound containing one or moremembered 6- unsaturated hydrocarbon rings, wherein the unsaturation may be represented formally by three conjugated double bonds and which may optionally be substituted at one or more carbon atoms of such rings by independently selected alkyl groups, and includes, for example, phenyl, naphthyl, methylphenyl, dimethoxyphenyl, 5- isopropyl-2-methylphenyl, meth- 25 ylphenyl, t-butylphenyl, nonylphenyl. [0020] In one embodiment, each R is independently(C1-C30)alkyl or (C1-C30)aryl. As used herein in reference to an organic group, the notation "(Cn-Cm)" where n and m are each positive integers, mean that the group contains from n carbon atoms to m carbon atoms per group.

[0021] In one embodiment, each R is independently (C 5-C30) alkyl, more typically (C10-C30) alkyl, or (C1-C30) alkyl. 30 [0022] In one embodiment, each R is independently (C 1-C9) alkyl, more typically (C1-C4) alkyl. [0023] Suitable organophosphites include, for example, tris(butyl)phosphite, tris(octyl)phosphite, tris(phenyl)phos- phite, tris(nonylphenyl)phosphite, tris(butyltripentyl)phosphite tris(2,4-di-t-butyl)phosphite. [0024] In one embodiment, the organophosphite antioxidant comprises a trialkyl phosphite is preferably one wherein each alkyl group of said trialkyl phosphite component has less than 9 carbon atoms, more preferably from 3 (e.g. tri- n- 35 propyl or tri-isopropyl) to 5 (e.g. tri-n-pentyl, tri-sec-pentyl, or tri-neo-pentyl) carbon atoms, and is most preferably a tributyl phosphite selected from the group consisting of n- butyl, sec-butyl, iso-butyl, and tert-butyl. Each of the three alkyl groups in a given molecule may be the same or different, so long as each has less than 10, more preferably less than 9 and even more preferably less than 8 carbon atoms, i.e. from 1 to 7 carbon atoms. Each alkyl group may be straight- chained or branched. 40 [0025] The first antioxidant and second antioxidant are included in an amount effective to stabilize the color of the hardener composition, typically for a time period of greater than or equal to about one month, more typically greater than or equal to one year, at about 25°C. A color stabilizingly effective amount is typically from 0.01 to 3.0, preferably from 0.1 to 2.0, most preferably from 0.2 to 1.0 combined total weight % of the first antioxidant and second antioxidant, based on the total weight of the polyisocyanate composition in which they are admixed. 45 [0026] The weight ratio of first antioxidant compound to second antioxidant employed in the color stabilized composition and process of this invention, when both are included, is typically approximately equal on a weight basis, but may vary widely, e.g. from 10:1 to 1:10, more typically in the range of from 2: 1 to 1:2, even more typically from 1.5:1 to 1:1.5 and most typically about 1:1. [0027] The color stabilizing components of this invention can be employed in any suitable polyisocyanate to be used 50 to produce polyurethanes therefrom. Such polyisocyanates can be monomeric polyisocyanates or polyisocyanate oli- gomers or prepolymers with some pendant NCO groups. Polyfunctional isocyanates have the general formula:

O=C=N-Y-(N=C=O)n

55 wherein Y is an aromatic, aliphatic or cycloaliphatic polyvalent group and n is or 1 or more. Examples of suitable isocyanates are isophorone diisocyanate, 1,3- and 1,4- cyclohexane diisocyanate, 1,2- ethylene diisocyanate, 1,4- tetram- ethylene diisocyanate, 1,6-hexamethylene diisocyanate, 2,2,4 and 2,4,4-trimethyl-1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, alpha, alpha’-diisocyanatodipropyl ether, 1,3- cyclobutane diisocyanate, 2,2- and 2,6- diiso-

4 EP 1 732 965 B1

cynanato-1-methylcyclohexane, 2,5 and 3,5- bis(isocyanatomethyl)-8-methyl-1,4-methano-decahydronaphthalene, 1,5-, 2,5-, 1,6- and 2,6- bis(isocyantomethyl)-4,7-methanohexahydroindane, 1,5-, 2,5- and 2,6- bis (isocyanato)-4,7-methane- hexahydroindane, 2,4’- and 4,4’-dicylohexyl diisocyanate, 2,4- and 2,6-hexahydrotolylene diisocyanate, perhydro-2,4’- and 4,4’-diphenylmethane diisocyanate, alpha,alpha’-diisocyanato-1,4-diethylbenzene, 1,3-and 1,4-phenylene diisocy- 5 anate, 4,4’-diisocyanatobiphenyl, 4,4’-diisocyanato-3,3’-dichlorobiphenyl, 4,4’-diisocyanato-3,3’-dimethoxybiphenyl, 4,4’-diisocyanato-3,3’-dimethylbiphenyl, 4,4’-diisocyanato-3,3’-diphenylbiphenyl, 2,4’- and 4,4’-diisocyanato diphenyl- methane, naphthylene 1,5-diisocyanate, 2,4- and 2; 6-tolylene diisocyanate, N, N’-(4,4’-dimethyl-3,3’-diisocyanatodiphe- nyl)uretdione, m-xylylene diisocyanate, dicyclohexylmethane diisocyanate, tetramethylxylylene diisocyanate, 2,4,4’-tri- isocyanatodiphenyl ether, 4,4’,4"-triisocyanatotriphenylmethane, and mixtures thereof. 10 [0028] Suitable polyisocyanate oligomers are compounds that comprise two or more isocyanate functional monomeric repeating units per molecule, including polyisocyanate dimers, polyisocyanate trimers, products of condensation of two or more polyisocyanate dimers, such as, bis-dimers, products of condensation of two or more polyisocyanate trimers, such as bis-trimers, as well as various condensation products dimers with trimers, and are typically obtained by con- densation of isocyanate monomers. Examples of suitable polyisocyanate oligomers include 2,4,6-trioxo-hexahydro- 15 1,3,5-triazine, 6-imino-5-oxa-1,3-diazine-2,4-dione, 6-imino-1,3,5-triazine-2,4-dione, 5-oxa-1,3-diazine2,4,6-trione, ure- tidine-2,4-dione, 4-imono-2-oxo-1,3-diazetidine, as well as urethanes or esters of carbamic acid, allophonate, urea, biuret, and carbodiimide. As further examples of such polyisocyanate oligomers, there may be mentioned hexamethylene diisocyanate trimers (HDI-trimers) such as Tolonate HDT from Rhodia, Inc. Examples of other suitable polyisocyanate oligomers are aliphatic polyisocyanate oligomers such as those derived from isophorone diisocyanate, hexamethylene 20 diisocyanate trimers consisting of high or low viscosity hexamethylene diisocyanate derivatives, and norbornene diiso- cyanate biurets and trimers. The isocyanate will typically be unblocked, i.e. will have free isocyanate functionality, in the compositions of this invention. [0029] In one embodiment, the polyisocyanate comprises, on average, from greater than 1 to 20, more typically from 2 to 20, even more typically from 2.5 to 10, isocyanate groups per molecule of the polyisocyanate. 25 [0030] The color stabilizer components of this invention are particularly effective in color stabilizing for substantially anhydrous solutions of polyisocyanate oligomers, such as solvent solutions of such polyisocyanate oligomers containing from 35 to 90 weight % solids. [0031] The color stabilizing compounds of this invention may be added to the polyisocyanates neat or in any suitable organic solvent compatible with the color stabilizer compounds and the polyisocyanate oligomers, such as aprotic sol- 30 vents, for example, oxygenated hydrocarbons (e.g. ketones, esters, ethers, glycol esters, and glycol ether esters), halogenated hydrocarbons, and aliphatic and/or aromatic hydrocarbons, and mixtures thereof. A typical oxygenated solvent is butyl acetate and a typical alkaryl hydrocarbon is mixed isomers of xylene. Typically, the solvent will be a mixture of a major amount of oxygenated hydrocarbons and a minor amount of aliphatic and/or aromatic hydrocarbons, e.g. in a weight ratio of from 4:1 to 1.5:1. The amount of solvent in the isocyanate compositions will typically be from 35 65% to 10 %, more typically from 50 % to 20%, by weight of the composition. [0032] It has been found that the color stabilizing composition is effective even when the isocyanate composition also contains a catalyst for the reaction of the isocyanate and a reactive hydrogen compound. [0033] Examples of such catalysts are tertiary amines or amidines and organometallic compounds and mixtures thereof. Suitable amines are both acyclic and, in particular, cyclic compounds, such as triethylenediamine, tetramethyl 40 butanediamine, 1,4-diazabicyclooctane (DABCO), 1,8-diazabicyclo-(5.4.0)-undecene, N,N-dimethylcyclohexyl amine, and N,N-dimethyl ethanolamine, as well as mixtures thereof. Suitable organometallic compounds include organotin, organozinc, organobismuth, and organozirconium compounds, as well as mixtures thereof. [0034] The catalysts preferably used are in particular organo-tin compounds. Organo-tin compounds are compounds containing both tin and an organic component, more particularly compounds containing one or more Sn- C bonds. Organic 45 compounds in the broader sense also include, for example, salts such as tin (II) octoate and tin (II) stearate. Tin compounds 1 in the narrower sense include, above all, compounds of tetravalent tin corresponding to the general formula R n+1SnX3-n, where n is a number of 0 to 2, R 1 is an alkyl, aryl, alkaryl and/or aralkyl group and finally X is an oxygen, sulfur or nitrogen compound. The groups R1 or X may even be attached to one another and, in that case, form a ring together with the tin. Such compounds are described in EP 491 268, EP 490 277 and EP 423 643. R1 best contains at least 4 carbon 50 atoms and, more particularly, at least 8 carbon atoms. The upper limit is generally 12 carbon atoms. In a preferred embodiment, n=0 or 1 and a mixture of 1 and 0. X is preferably an oxygen compound, i.e. an organotin oxide, hydroxide, alcoholate, beta-dicarbonyl compound, carboxylate or ester of an inorganic acid. However, X may also be a sulfur compound, i.e. an organotin sulfide, thiolate or thioacid ester. Among the Sn-S compounds, thioglycolic esters, for example compounds containing the following groups: 55

-S-CH2-CH2 -CO-O-(CH2)10-CH3

or

5 EP 1 732 965 B1

-S-CH2-CH2-CO-O-CH2-CH(C2H5)-CH2-CH2-CH2-CH3

are of particular interest. Compounds such as these meet another criterion, namely: the molecular weight of the organo- 5 tin compound should preferably be above 400 and, more particularly, above 250, more preferably above 600. [0035] A preferred class of compounds are the dialkyl tin (IV) carboxylates (X=O-CO-R1). The carboxylic acids contain 2, preferably at least 10 and more preferably 14 to 32 carbon atoms. In one embodiment, the catalyst comprises a dialkyltin dicarboxylate, wherein the alkyl groups of the dialkyltin dicarboxylate are each independently selected from alkyl groups containing from 1 to 12 carbon atoms per group and the carboxylate groups of the dialkyltin dicarboxylate 10 are each independently selected carboxylate groups containing from 2 to 32 carbon atoms per group. Dicarboxylic acids may also be used. The following are specifically mentioned as acids: adipic acid, maleic acid, fumaric acid, malonic acid, succinic acid, pimelic acid, terephthalic acid, phenyl acetic acid, benzoic acid, acetic acid, propionic acid and, in particula r, 2-ethylhexanoic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid and stearic acid. Specific dialkyl tin carboxylates include dibutyl tin diacetate, dioctyl tin diacetate, dibutyl tin maleate, dibutyl tin bis-(2-ethylhexoate), 15 dibutyl tin dilaurate; tributyl tin acetate, bis-(beta- methoxycarbonylethyl)-tin dilaurate and bis-(beta- acetylethyl)-tin dilau- rate. [0036] Tin oxides and sulfides and also thiolates may also be used. Specific compounds are bis-(tributyl tin)-oxide, bis-(trioctyl tin)-oxide, dibutyl and dioctyl tin- bis-(2-ethylhexyl thiolate), dibutyl and dioctyl tin didodecyl thiolate, bis-(beta- methoxycarbonyl ethyl)-tin didodecyl thiolate, bis-(beta-acetyl ethyl)-tin-bis-(2-ethyl hexyl thiolate), dibutyl and dioctyl 20 tin didodecyl thiolate, butyl and octyl tin tris-(thioglycolic acid-2-ethyl hexoate), dibutyl and dioctyl tin-bis-(thioglycolic acid-2-ethyl hexoate), tributyl and trioctyl tin-(thioglycolic acid-2-ethyl hexoate) and butyl and octyl tin tris-(thioethylene glycol-2-ethyl hexoate), dibutyl and dioctyl tin-bis-(thioethylene glycol-2-ethyl hexoate), tributyl and trioctyl tin-(thioeth- ylene glycol-2-ethyl hexoate) with the general formula

25 Rn+1 Sn(SCH2CH·2OCOC8H17)-n,

where R is a C 4-8 alkyl group, bis-(beta-methoxycarbonyl ethyl)-tin- bis-(thioethylene glycol-2-ethyl hexoate), -tin-bis-(thi- oglycolic acid-2-ethyl hexoate) and bis-(beta-acetyl ethyl)-tin-bis-(thioethylene glycol-2-ethyl hexoate) and -tin-bis-(thi- oglycolic acid-2-ethyl hexoate). 30 [0037] The other groups of tin compounds mentioned include tributyl tin hydroxide, dibutyl tin diethylate, dibutyl tin dibutylate, dihexyl tin dihexylate, dibutyl tin diacetyl acetonate, dibutyl tin diethyl acetyl acetate, bis-(butyl dichlorotin) -ox- ide, bis-(dibutyl chlorotin)-sulfide, dibutyl and dioctyl tin dichloride, dibutyl- and dioctyl tin dithioacetate. [0038] In one embodiment, the hardener composition comprises a catalytically effective amount of catalyst. The term "catalytically effective amount" means a substoichiometric amount of catalyst relative to a reactant. As used herein, a 35 catalytically effective amount is typically from 10 to 5,000 parts by weight ("pbw") catalyst per 1,000,000 pbw polyiso- cyanate, more typically from 100 to 2,500 pbw catalyst per 1,000,000 pbw polyisocyanate. [0039] The hardener composition of the present invention is used by combining the hardener with a reactive hydrogen compound, for example, a polyol, to form a reactive coating composition. Suitable polyols are known in the art and include, for example, polyester polyols and acrylic polyols. 40 [0040] The invention is illustrated by, but not limited to, the following examples conducted with Tolonate HDT (hex- amethylene diisocyanate trimer).

EXAMPLES

45 [0041] Samples of hardener compositions, containing Tolonate HDT, BHT, Tributylphosphite (TBP) and Triisooctyl- phophite (TioP) and dibutyltindilaurate (DBTDL) in the relative amounts set forth below in TABLE I were made in a 1: 1: 0.5 blend by weight of butyl acetate/methyl amyl ketone/xylene. These samples were prepared using a screening ex- perimental design series varying % solids, catalyst concentration, BHT and phosphite concentration. Catalyst concen- tration is based upon % solids. 50 [0042] The samples were aged in a 60°C oven for respective periods of 1, 2 and 4 weeks. APHA values were obtained fro the aged samples using a Minolta CT-31 0 colorimeter equipped with a 10mm path length cell. APHA values were put into the statistical design program JMP and the data analyzed. A model was made with an R-squared adjusted = 0.84 using the 4 week APHA values. [0043] The following are the results based on the model at a catalyst concentration of 1000ppm: 55

6 EP 1 732 965 B1

TABLE I % Solids Phosphite Phenol Phosphite Concentration Phenol Concentration APHA 50 TBP BHT 0.1 0.1 66 5 75 TBP BHT 0.1 0.1 115 75 TioP BHT 0.1 0.1 128 50 TBP BHT 0.5 0.5 15

10 50 TioP BHT 0.5 0.5 28 75 TBP BHT 0.5 0.5 63 75 TioP BHT 0.5 0.5 76 50 TBP BHT 0.3 0.3 40 15 75 TBP BHT 0.3 0.3 88

Claims

20 1. A hardener composition for use as the first component of a two component polyurethane coating composition, wherein the second component is an active hydrogen compound; the hardener composition comprising:

one or more aliphatic polyisocyanate oligomers selected from a polyisocyanate dimer, a polyisocyanate trimer, a product of condensation of two or more polyisocyanate dimers, a product of condensation of two or more 25 polyisocyanate trimers, or a condensation product of dimers with trimers, derived from isophorone diisocyanate, ethylene diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, decamethylene diisocy- anate, or norbornene diisocyanate, a catalyst for promoting reaction of the polyisocyanate with a reactive hydrogen compound, a first antioxidant comprising one or more of sterically hindered phenol antioxidants and secondary aryl amine 30 antioxidants, and a second antioxidant comprising one or more organophosphite antioxidants according to the formula:

(RO)3P

35 wherein each R is independently alkyl or aryl.

2. The hardener composition of claim 1, wherein the catalyst comprises a tertiary amine, an amidine, an organometallic compound, or a mixture thereof.

40 3. The hardener of claim 1, wherein the catalyst comprises a dialkyl tin carboxylate, wherein the alkyl groups of the dialkyltin dicarboxylate are each independently selected from alkyl groups containing from 1 to 12 carbon atoms per group and the carboxylate groups of the dialkyltin dicarboxylate are each independently selected carboxylate groups containing from 2 to 32 carbon atoms per group.

45 4. The hardener of claim 1, wherein the first antioxidant comprises one or more sterically hindered phenols selected from 2,4-dimethyl-6-butylphenol, 4,4’-methylene-bis(2,6-di-tert-butylphenol), and 2,6-ditert.butyl-N-N’dimethylami- no-p-cresol, butylated hydroxyanisole, 2,6- di-tertbutylphenol, 2,4,6-tri-tertbutylphenol, 2-tert-butylphenol, 2,6-diiso- propylphenol, 2-methyl-6-tert-butylphenol, 2,4-dimethyl-6-tertbutylphenol, 4-(N,N-dimethylaminomethyl)-2,8-di-ter- tbutylphenol, and 4-ethyl-2,6-di-tertbutylphenol. 50

5. The hardener of claim 1, wherein the organophosphite comprises one or more organophosphite selected from tris (butyl)phosphite, tris(octyl)phosphite, tris(phenyl)phosphite, tris(nonylphenyl)phosphite, tris(butyltripentyl)phos- phite, and tris(2,4-di-t-butyl)phosphite.

55 6. The hardener of claim 1, wherein the hardener further comprises an organic solvent.

7. A stable isocyanate composition useful in a catalyzed reaction with an active hydrogen compound, comprising one

7 EP 1 732 965 B1

or more aliphatic polyisocyanate oligomers as defined in claim 1; a stabilizer comprising a trialkyl phosphite com- ponent, each alkyl group of said trialkyl phosphite component having less than 10 carbon atoms; and a phenolic antioxidant.

5 8. Use of a combination of a phenolic antioxidant component and a trialkyl phosphite component, wherein each alkyl group of said trialkyl phosphite component has less than 10 carbon atoms, for stabilizing the colour of an isocyanate.

9. The use as claimed in claim 8 wherein said phenolic antioxidant is a butylated hydroxytoluene.

10 10. The use as claimed in claim 8 wherein said phenolic antioxidant is a butylated hydroxyanisole.

11. A method for making a color stabilized hardener composition for use as a component of a polyurethane coating composition, comprising combining a polyisocyanate oligomer as defined in claim 1, a catalyst for promoting reaction of the polyisocyanate with a reactive hydrogen compound, a first antioxidant comprising a sterically hindered phenol 15 or a secondary aryl amine or a mixture thereof, and a second antioxidant comprising one or more organophosphites as defined in claim 1.

12. A method for stabilizing the color of a hardener composition for use as a component of a polyurethane coating composition, said hardener composition comprising a polyisocyanate as defined in claim 1 and a catalyst for pro- 20 moting reaction of the polyisocyanate with a reactive hydrogen compound, comprising adding to the hardener composition a color stabilizing amount of

a first antioxidant comprising one or more of sterically hindered phenol antioxidants and secondary aryl amine antioxidants, and 25 a second antioxidant comprising one or more organophosphite antioxidants, as defined in claim 1.

Patentansprüche

30 1. Härterzusammensetzung zur Verwendung als erste Komponente von einer Zweikomponenten-Polyurethan-Be- schichtungszusammensetzung, worin die zweite Komponente eine aktive Wasserstoffverbindung ist; wobei die Härterzusammensetzung Folgendes umfasst:

ein oder mehrere aliphatische Polyisocyanat-Oligomere, die aus Folgenden ausgewählt sind: einem Polyiso- 35 cyanat-Dimer, einem Polyisocyanat-Trimer, einem Produkt der Kondensation von zwei oder mehr Polyisocya- nat-Dimeren, einem Produkt der Kondensation von zwei oder mehr Polyisocyanat-Trimeren oder einem Kon- densationsprodukt von Dimeren mit Trimeren, die von Folgenden abstammen: Isophorondiisocyanat, Ethylen- diisocyanat, Tetramethylendiisocyanat, Hexamethylendiisocyanat, Decamethylendiisocyanat oder Norbornen- diisocyanat, 40 einen Katalysator zur Begünstigung der Reaktion des Polyisocyanats mit einer reaktiven Wasserstoffverbin- dung, ein erstes Antioxidationsmittel, das ein oder mehrere von sterisch gehinderten Phenolen als Antioxidationsmittel und sekundären Arylaminen als Antioxidationsmittel umfasst, und ein zweites Antioxidationsmittel, das ein oder mehrere Organophosphite als Antioxidationsmittel nach der fol- 45 genden Formel umfasst:

(RO)3P,

worin jedes R unabhängig Alkyl oder Aryl darstellt. 50 2. Härterzusammensetzung nach Anspruch 1, worin der Katalysator ein tertiäres Amin, ein Amidin, eine metallorga- nische Verbindung oder eine Mischung davon umfasst.

3. Härter nach Anspruch 1, worin der Katalysator ein Dialkylzinncarboxylat umfasst, worin die Alkylgruppen des Dial- 55 kylzinndicarboxylats jeweils unabhängig aus Alkylgruppen ausgewählt sind, die 1 bis 12 Kohlenstoffatome pro Gruppe enthalten, und die Carboxylatgruppen des Dialkylzinndicarboxylats jeweils unabhängig aus Carboxylatgrup- pen ausgewählt sind, die 2 bis 32 Kohlenstoffatome pro Gruppe enthalten.

8 EP 1 732 965 B1

4. Härter nach Anspruch 1, worin das erste Antioxidationsmittel ein oder mehrere sterisch gehinderte Phenole umfasst, die aus Folgenden ausgewählt sind: 2,4- Dimethyl-6-butylphenol, 4,4’-Methylenbis(2,6-di-tert-butylphenol) und 2,6- Di-tert-butyl-N,N’-dimethylamino-p-kresol, butyliertem Hydroxyanisol, 2,6-Di-tert-butylphenol, 2,4,6-Tri-tert-butyl- phenol, 2-tert-Butylphenol, 2,6-Diisopropylphenol, 2-Methyl-6-tert-butylphenol, 2,4-Dimethyl-6-tert-butylphenol, 5 4-(N,N-Dimethylaminomethyl)-2,8-di-tert-butylphenol und 4-Ethyl-2,6-di-tert-butylphenol.

5. Härter nach Anspruch 1, worin das Organophosphit ein oder mehrere Organophosphite umfasst, die aus Folgenden ausgewählt sind: Tris(butyl)phosphit, Tris(octyl)phosphit, Tris(phenyl)phosphit, Tris(nonylphenyl)phosphit, Tris(bu- tyltripentyl)phosphit und Tris(2,4-di-t-butyl)phosphit. 10 6. Härter nach Anspruch 1, worin der Härter weiter ein organisches Lösungsmittel umfasst.

7. Stabile Isocyanatzusammensetzung, die in einer katalysierten Reaktion mit einer aktiven Wasserstoffverbindung verwendbar ist und Folgendes umfasst: 15 ein oder mehrere aliphatische Polyisocyanat- Oligomere, wie in Anspruch 1 definiert; einen Stabilisator, der eine Trialkylphosphit-Komponente umfasst, wobei jede Alkylgruppe der genannten Trialkylphosphit-Komponente weniger als 10 Kohlenstoffatome aufweist; und ein phenolisches Antioxidationsmittel.

20 8. Verwendung einer Kombination aus einem phenolischen Antioxidationsmittel als Komponente und einer Trialkylp- hosphit-Komponente, worin jede Alkylgruppe der genannten Trialkylphosphit-Komponente weniger als 10 Kohlen- stoffatome aufweist, zur Stabilisierung der Farbe eines Isocyanats.

9. Verwendung nach Anspruch 8, worin das genannte phenolische Antioxidationsmittel ein butyliertes Hydroxytoluol ist. 25 10. Verwendung nachAnspruch 8,worin das genannte phenolischeAntioxidationsmittel ein butyliertes Hydroxyanisol ist.

11. Verfahren für die Herstellung einer farbstabilisierten Härterzusammensetzung zur Verwendung als Komponente von einer Polyurethan-Beschichtungszusammensetzung, das Folgendes umfasst: Vereinigen eines Polyisocyanat- 30 Oligomers, wie in Anspruch 1 definiert, eines Katalysators zur Begünstigung der Reaktion des Polyisocyanats mit einer reaktiven Wasserstoffverbindung, eines ersten Antioxidationsmittels, das ein sterisch gehindertes Phenol oder ein sekundäres Arylamin oder eine Mischung davon umfasst, und eines zweiten Antioxidationsmittels, das ein oder mehrere Organophosphite, wie in Anspruch 1 definiert, umfasst.

35 12. Verfahren für die Stabilisierung der Farbe einer Härterzusammensetzung zur Verwendung als Komponente von einer Polyurethan-Beschichtungszusammensetzung, wobei die genannte Härterzusammensetzung ein Polyisocya- nat, wie in Anspruch 1 definiert, und einen Katalysator zur Begünstigung der Reaktion des Polyisocyanats mit einer reaktiven Wasserstoffverbindung umfasst, das das Zugeben einer farbstabilisierenden Menge von Folgenden zur Härterzusammensetzung umfasst: 40 eines ersten Antioxidationsmittels, das ein oder mehrere sterisch gehinderte Phenole als Antioxidationsmittel und sekundäre Arylamine als Antioxidationsmittel umfasst, und eines zweiten Antioxidationsmittels, das ein oder mehrere Organophosphit- Antioxidationsmittel, wie in Anspruch 1 definiert, umfasst. 45

Revendications

1. Composition de durcisseur à utiliser comme le premier composant d’une composition de revêtement au polyuréthane 50 de deux composants, dans laquelle le deuxième composant est un composé à l’hydrogène actif ; la composition de durcisseur comprenant :

un ou plusieurs oligomères de polyisocyanate aliphatique sélectionnés parmi un dimère de polyisocyanate, un trimère de polyisocyanate, un produit de la condensation de deux dimères de polyisocyanate ou plus, un produit 55 de la condensation de deux trimères de polyisocyanate ou plus, ou un produit de la condensation de dimères avec des trimères, dérivés du diisocyanate isophorone, du diisocyanate d’éthylène, du diisocyanate de tétra- méthylène, du diisocyanate d’hexaméthylène, du diisocyanate de décaméthylène, ou du diisocyanate de nor- bornène,

9 EP 1 732 965 B1

un catalyseur pour promouvoir la réaction du polyisocyanate avec un composé à l’hydrogène réactif, un premier antioxydant comprenant un ou plusieurs parmi des antioxydants phénoliques à encombrement stérique et des antioxydants arylamine secondaires, et un deuxième antioxydant comprenant un ou plusieurs antioxydants organophosphite selon la formule : 5

(RO)3P

dans laquelle chaque R est indépendamment alkyle ou aryle.

10 2. Composition de durcisseur selon la revendication 1, dans laquelle le catalyseur comprend une amine tertiaire, une amidine, un composé organométallique, ou un mélange de ceux- ci.

3. Durcisseur selon la revendication 1, dans lequel le catalyseur comprend un carboxylate de dialkylétain, dans lequel les groupes alkyle du dicarboxylate de dialkylétain sont chacun indépendamment sélectionnés à partir de groupes 15 alkyle contenant de 1 à 12 atomes de carbone par groupe et les groupes carboxylate du dicarboxylate de dialkylétain sont chacun des groupes carboxylate indépendamment sélectionnés contenant de 2 à 32 atomes de carbone par groupe.

4. Durcisseur selon la revendication 1, dans lequel le premier antioxydant comprend un ou plusieurs phénols à en- 20 combrement stérique sélectionnés parmi 2,4- diméthyl-6-butylphénol, 4,4’-méthylène-bis(2,6-di-tert-butylphénol), et 2,6-ditert-butyl-N-N’diméthylamino-p-crésol, de l’hydroxyanisol butylé, 2,6- di-tertbutylphénol, 2,4,6-tri-tertbutylphé- nol, 2-tert-butylphénol, 2,6-diisopropylphénol, 2-méthyl-6-tert-butylphénol, 2,4-diméthyl-6-tertbutylphénol, 4-(N,N- diméthylaminométhyl)-2,8-di-tertbutylphénol, et 4-éthyl-2,6-di-tertbutylphénol.

25 5. Durcisseur selon la revendication 1, dans lequel l’organophosphite comprend un ou plusieurs organophosphites sélectionnées parmi tris (butyl)phosphite, tris(octyl)phosphite, tris(phényl)phosphite, tris(nonylphényl)phosphite, tris (butyltripentyl)phosphite, et tris(2,4-di-t-butyl)phosphite.

6. Durcisseur selon la revendication 1, dans lequel le durcisseur comprend en outre un solvant organique. 30 7. Composition d’isocyanate stable utile dans une réaction catalysée avec un composé à l’hydrogène actif et compre- nant un ou plusieurs oligomères de polyisocyanate aliphatique comme définis à la revendication 1 ; un stabilisateur comprenant un composant au trialkylphosphite, chaque groupe alkyle dudit composant au trialkylphosphite ayant moins de 10 atomes de carbone ; et un antioxydant phénolique. 35 8. Utilisation d’une combinaison d’un composant d’antioxydant phénolique et d’un composant au trialkylphosphite, dans laquelle chaque groupe alkyle dudit composant au trialkylphosphite a moins de 10 atomes de carbone, pour stabiliser la couleur d’un isocyanate.

40 9. Utilisation selon la revendication 8, dans laquelle ledit antioxydant phénolique est un hydroxytoluène butylé.

10. Utilisation selon la revendication 8, dans laquelle ledit antioxydant phénolique est un hydroxyanisole butylé.

11. Procédé de fabrication d’une composition de durcisseur à couleur stabilisée à utiliser comme un composant d’une 45 composition de revêtement au polyuréthane, comprenant de combiner un oligomère de polyisocyanate comme défini à la revendication 1, un catalyseur pour promouvoir la réaction du polyisocyanate avec un composé à l’hy- drogène réactif, un premier antioxydant comprenant un phénol à encombrement stérique ou une arylamine secon- daire ou un mélange de ceux-ci, et un deuxième antioxydant comprenant un ou plusieurs organophosphites tels que définis à la revendication 1. 50 12. Procédé de stabilisation de la couleur d’une composition de durcisseur à utiliser comme un composant d’une composition de revêtement au polyuréthane, ladite composition de durcisseur comprenant un polyisocyanate tel que défini à la revendication 1 et un catalyseur pour promouvoir la réaction du polyisocyanate avec un composé à l’hydrogène réactif, comprenant d’ajouter à la composition de durcisseur une quantité stabilisant la couleur 55 d’un premier antioxydant comprenant un ou plusieurs parmi des antioxydants phénoliques à encombrement stérique et des antioxydants arylamine secondaires, et d’un deuxième antioxydant comprenant un ou plusieurs antioxydants organophosphite, tels que définis à la reven- dication 1.

10 EP 1 732 965 B1

REFERENCES CITED IN THE DESCRIPTION

This list of references cited by the applicant is for the reader’s convenience only. It does not form part of the European patent document. Even though great care has been taken in compiling the references, errors or omissions cannot be excluded and the EPO disclaims all liability in this regard.

Patent documents cited in the description

• US 4297 A [0004] • US 6043332 A [0005] • US 472 A [0004] • EP 0735027 A [0005] • US 4065 A [0004] • GB 1102387 A [0005] • US 362 A [0004] • US 2002115782 A [0005] • US 3715 A [0004] • DE 1802659 [0005] • US 381 A [0004] • US 3069369 A [0005] • US 2957 A [0004] • GB 923190 A [0005] • US 903 A [0004] • US 3115465 A [0005] • US 4677154 A [0004] • US 4305839 A [0005] • EP 0425710 A [0005] • WO 9419385 A [0005] • EP 0210859 A [0005] • EP 491268 A [0034] • WO 9814492 A [0005] • EP 490277 A [0034] • US 5719229 A [0005] • EP 423643 A [0034]

11