Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/08—Processes
  • C08G18/16—Catalysts
  • C08G18/22—Catalysts containing metal compounds
  • C08G18/222—Catalysts containing metal compounds metal compounds not provided for in groups C08G18/225 - C08G18/26
• • C—CHEMISTRY; METALLURGY
  • C07—ORGANIC CHEMISTRY
  • C07C—ACYCLIC OR CARBOCYCLIC COMPOUNDS
  • C07C269/00—Preparation of derivatives of carbamic acid, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups
  • C07C269/02—Preparation of derivatives of carbamic acid, i.e. compounds containing any of the groups, the nitrogen atom not being part of nitro or nitroso groups from isocyanates with formation of carbamate groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/08—Processes
  • C08G18/16—Catalysts
  • C08G18/22—Catalysts containing metal compounds
  • C08G18/24—Catalysts containing metal compounds of tin
  • C08G18/244—Catalysts containing metal compounds of tin tin salts of carboxylic acids
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/08—Processes
  • C08G18/16—Catalysts
  • C08G18/22—Catalysts containing metal compounds
  • C08G18/24—Catalysts containing metal compounds of tin
  • C08G18/248—Catalysts containing metal compounds of tin inorganic compounds of tin
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G18/00—Polymeric products of isocyanates or isothiocyanates
  • C08G18/06—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen
  • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
  • C08G18/72—Polyisocyanates or polyisothiocyanates
  • C08G18/74—Polyisocyanates or polyisothiocyanates cyclic
  • C08G18/75—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic
  • C08G18/751—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic containing only one cycloaliphatic ring
  • C08G18/752—Polyisocyanates or polyisothiocyanates cyclic cycloaliphatic containing only one cycloaliphatic ring containing at least one isocyanate or isothiocyanate group linked to the cycloaliphatic ring by means of an aliphatic group
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G2150/00—Compositions for coatings
  • C08G2150/20—Compositions for powder coatings

Definitions

• the invention relates to a catalyst for a reaction between a compound that can react with isocyanate groups and an aliphatic diisocyanate with one isocyanate group bound to a primary carbon atom and one isocyanate group bound to a tertiary carbon atom.
• An aliphatic diisocyanate with one isocyanate group bound to a primary carbon atom and one isocyanate group bound to a tertiary carbon atom is a compound containing two or more isocyanate groups having different reactivities.
• the two isocyanate groups in 3(4)-isocyanatomethyl-l-methylcyclohexylisocyanate (IMCI) differ in reactivity.
• this diff ⁇ xence in reactivity can be used in the case of a compound containing two or more isocyanate groups with different reactivities to cause certain isocyanate groups to react selectively with a compound that can react with isocyanate groups, while the other isocyanate groups remain unchanged and will be available for use at a later stage in a similar or a different chemical reaction.
• Such reactions in which the selectivity is complete or almost complete under industrially applicable conditions are not yet known.
• the uncatalysed reactions between a compound containing two or more isocyanate groups with different reactivities and the compound that can react with isocyanate groups show substantially decreasing selectivities at higher temperatures. At room temperature the selectivity of the reaction is sufficient, but the reaction rate is too low. Moreover, the processing of some compounds that can react with isocyanate groups at this temperature is troublesome. It is the object of the invention to obtain a very high selectivity in the reaction between an aliphatic diisocyanate with one isocyanate group bound to a primary carbon atom and one isocyanate group bound to a tertiary carbon atom and a compound that can react with isocyanate groups, under the usual industrial conditions, with the reaction also taking place at a sufficiently high rate.
• the reaction temperature may vary from room temperature in the case of liquid media, to above 100°C in the case of highly viscous media, such as polymers with high glass transition temperatures.
• the invention is characterised in that the catalyst is an ionogenic metal complex based on a metallic element from one of the groups III, IV or VII of the Periodic System, with at least one exchangeable counterion. This invention ensures that the reaction takes place at a high rate and that moreover a very high selectivity is obtained.
• the use of the catalyst according to the invention ensures that the coupling of the diisocyanate to for example a hydroxyl-functional polymer takes place exclusively or almost exclusively via the most reactive isocyanate group.
• Advantages of this selective coupling are for example that the product polymer for example a coating contains no free diisocyanate and that no chain lengthening takes place.
• Suitable metallic elements in the suitable valency are aluminium(III) , tin(IV), manganese(III) , titanium(III) , titanium(IV) and zirconium(IV) .
• the preferred metallic element is tin(IV), titanium(IV) , manganese(III) and zirconium(IV) .
• the number of counterions lies between 1 and 4.
• Suitable counterions are halogenides, preferably chloride, ( C_-C 20 ) alkoxides, preferably ( C_-C ⁇ ) alkoxide, (C 2 -C 2n .) carboxylates, preferably (C 2 -C ⁇ ) carboxylates, enolates, preferably of 2 , 4-pentanedione (acetoacetonates) , and alkyl esters of malonic acid and acetoacetic acid, phenolates, naphthenates, cresylates and mixtures of said counte ions.
• Suitable catalysts are aluminium(III) acetate, aluminium(lll) acetoacetonate, aluminium(III)2 ,2,6,6-tetrameth l-3, 5-heptanedionate, aluminium(III) ethoxide, aluminium(III) isopropoxide, aluminium(III) sec-butoxide, aluminium(III) tert- butoxide, tin(IV) chloride, tin(IV) bromide, tin(IV)iodide, tin(IV) acetate, tin(IV) bis(acetoacetonate) dichloride, tin(IV) bis(acetoacetonate) dibromide, manganese(III) acetate, manganese(III) acetoacetonate, manganese(III) fluoride, titanium(IV) chloride, titanium(IV) bromide, titanium(IV) methoxide, titanium(IV) ethoxide, titanium(IV
• Preferred catalysts are titanium(IV) butoxide, zirconium(IV) acetoacetonate, zirconium(IV) butoxide, tin(IV) acetate, manganese(III) acetoacetonate, titanium(IV) isopropoxide, zirconium (IV) 2-ethylhexanoate and tin(IV) chloride.
• the catalyst complex may also contain one or more neutral elements such as alkylcyanide, crown ether, (poly)ether, such as polytetrahydrofuran, polyethylene glycol or tetrahydrofuran, dialkylsulphide or tertiary amine.
• neutral elements such as alkylcyanide, crown ether, (poly)ether, such as polytetrahydrofuran, polyethylene glycol or tetrahydrofuran, dialkylsulphide or tertiary amine.
• the amount of catalyst is usually between 0.01 and 3 wt.% (relative to the compound that can react with isocyanate groups and the compound containing isocyanate groups).
• One of the additional advantages of the catalysts according to the invention in the case of use in coatings is that colourless catalysts can be chosen.
• Monomers, oligomers and polymers may all be used as the compounds that can react with isocyanate groups. Such compounds contain reactive groups that can form a chemical bond with isocyanate groups.
• Suitable reactive groups are alcohols, N-hydroxyl compounds such as oximes and N- hydroxyimides, amines, amides, for example N- alkoxyamides, lactams, imides, thiols, enolates such as 1,3-dicarbonyl compounds, carboxylates, epoxides and aromatic compounds containing heterocyclic nitrogen groups, such as pyrimidines, indoles, imidazoles, oxazoles, thiazoles, triazoles, pyrazoles and their derivatives.
• the aliphatic diisocyanate having one sterically more accessible isocyanate group bound to a primary carbon atom and one sterically less accessible isocyanate group bound to a tertiary carbon atom can be represented as follows by Formula (1)
• R 1 and R 2 contain the same or different (C 1 -C 4 ) alkyl groups and R 3 contains a bivalent, optionally branched, saturated aliphatic ( C_-C 10 ) hydrocarbon radical .
• the diisocyanate is a cycloaliphatic diisocyanates containing one sterically more accessible isocyanate group bound to a primary carbon atom and one sterically less accessible isocyanate group bound to a tertiary carbon atom.
• R 5 and R 6 the same or different bivalent, optionally branched, saturated, aliphatic hydrocarbon radicals
• diisocyanates examples include 1,4- diisocyanato-4-methyl-pentane, 1,5-diisocyanato-5- methylhexane, 3 (4 )-isocyanatomethyl-l- methylcyclohexylisocyanate, 1, 6-diisocyanato-6-methyl- heptane, 1,5-diisocyanato-2 ,2, 5-trimethylhexane and 1, 7-diisocyanato-3 , 7-dimethyloctane or 1-isocyanato-l- methyl-4-(4-isocyanatobut-2-yl)-cyclohexane, 1- isocyanato-l,2,2-trimethyl-3-(2-isocyanato-ethyl )- cyclopentane, 1-isocyanato-l, 4-dimethyl-4- isocyanatomethyl-cyclohexane, 1-isocyanato-l,3- dimethyl-3-isocyanate
• diisocyanates are described in for example DE-A-3608354, DE-A-3620821 and EP-A-153561.
• IMCI isocyanotomethyl-1-methylcyclohexylisocyanate
• DIMP 4-diisocyanate-4-methylpentane
• reaction according to the invention can be applied in a wide diversity of technical fields.
• a preferred field of application is the coating industry (in both powder paint systems and solvent- or water- based systems).
• Other suitable fields of application are, for example, construction resins, polyurethanes foams or compounds, lenses, materials based on acrylates, the preparation of resins for adhesives, sealants, compatibilisers, coupling agents and printing inks and also as chain extenders in engineering plastics.
• the compounds that can react with isocyanate groups can be chosen from polymers such as, for example amorphous and crystalline polyesters, polyurethanes, unsaturated polyesters, polyethers, polycarbonates, polybutadienes, styrene-maleic anhydride copolymers and fluorine- containing polymers.
• amorphous polyesters or polyacrylates are used as the polymer.
• Polyesters are generally based on units of aliphatic polyalcohols and polycarboxylic acids.
• the polyester may contain for example isophthalic acid, terephthalic acid, hexahydroterephthalic acid, 2 , 6-naphthalene dicarboxylic acid and 4 , -oxybisbenzoic acid, 3,6- dichlorophthalic acid, tetrachlorophthalic acid, itaconic acid, tetrahydrophthalic acid, hexahydroterephthalic acid, hexachloroendomethylene- tetrahydrophthalic acid, phthalic acid, azelaic acid, sebacic acid, decanedicarboxylic acid, adipic acid, succinic acid, trimellitic acid and maleic acid, fumaric acid, citraconic acid and mesaconic acid.
• These acids may be used as such or, insofar as available, in the form of their anhydrides, acid chlorides
• Use may also be made of hydroxycarboxylic acids and/or optionally lactones such as 12- hydroxystearic acid, hydroxypivalic acid and ⁇ - caprolactone.
• trifunctional alcohols or acids can be used to obtain branched polyesters.
• suitable polyols and polyacids are glycerol, hexanetriol, trimethylolethane, trimethylolpropane, tris-(2-hydroxyethyl )-isocyanurate and trimellitic acid.
• the preparation conditions and the COOH/OH ratio can be chosen so that end products are obtained that have a hydroxyl value that lies within the envisaged range of values.
• the hydroxyl value may for example lie between 20 and 100 mg of KOH/gram and the molecular weight (M n ) between 1000 and 10000.
• the polyesters can be prepared both in the presence of catalysts according to the invention and in the presence of the usual catalysts, via the usual process, through esterification or re-esterification.
• a catalyst according to the invention preferably titanium(IV) , zirconium(IV) , tin(IV) or aluminium(III) complexes, during the polyester synthesis for example presents the advantage that only one catalyst need be used in the various successive steps (the polymer synthesis, the reaction with a compound containing two or more isocyanate groups with different reactivities and optionally the curing step) and, moreover, that the desired reaction rates are coupled to an improved selectivity. It is also possible to use the usual catalysts during the polymer synthesis and during the curing.
• the acrylate polymer is based on alkylesters of (meth)acrylic acid, such as ethyl (meth)acrylate, isopropyl ( eth)acrylate, n-butyl (meth)acrylate, n-propyl (meth)acrylate, isobutyl (meth)acrylate, ethylhexyl acrylate and/or cyclohexyl (meth)acrylate, vinyl compounds such as styrene and vinyl acetate, malate, fumarate and itaconate.
• alkylesters of (meth)acrylic acid such as ethyl (meth)acrylate, isopropyl ( eth)acrylate, n-butyl (meth)acrylate, n-propyl (meth)acrylate, isobutyl (meth)acrylate, ethylhexyl acrylate and/or cyclohexyl (meth)acrylate, vinyl
• the hydroxyl-functional acrylate resins are generally based on hydroxyethyl (meth)acrylate, hydroxypropyl (meth)acrylate and alkyl (meth)acrylate.
• Acrylate resins can be prepared in a polymerisation in which first a solvent, for example toluene, xylene or butylacetate, is added to the reactor. This is followed by heating to the desired reaction temperature, for example the reflux temperature of the solvent used, after which an initiator and optionally mercaptan are added in a period of for example between 2 and 4 hours. Then the temperature is kept at reflux temperature for for example two hours. The solution is refluxed for 1 to 4 hours. The solvent is then removed through distillation by raising the temperature, after which a vacuum distillation can be carried out, for for example one to two hours. Then the product is drained and cooled.
• a solvent for example toluene, xylene or butylacetate
• modification for example using IMCI, may take place.
• the selective reaction results in isocyanate-functional polyacrylates without any chain lengthening taking place. In the case of highly functional polymers, chain lengthening may result in premature crosslinking.
• a further advantage of the selective reaction is that when the optimum ratio of OH and NCO groups is chosen to be at most 2, no free diisocyanate is observed after modification. The presence of free diisocyanate is unjustifiable in view of the toxic properties of the diisocyanate and the irritation that it causes.
• Isocyanate-functional polyacrylates can be further modified with the aid of, for example, hydroxyethyl(meth)acrylate, aminopropyl vinylether or hydroxybutyl vinyl ether, but they can also be used as such with crosslinkers. If an OH : NCO ratio of 1 : 1 is chosen in the functionalisation of the acrylate with for example IMCI, the selective reaction may result in a latent self-crosslinking system. As the remaining tertiary isocyanates have a low reactivity, the isocyanate-functional polyacrylates can be extruded or be dispersed in water or emulsified.
• mixing of the polymer with for example IMCI may take place at a temperature at which the polymer has a viscosity of less than 5000 dPas (measured according to Emila). This can be effected by using agents that result in a homogeneous composition, for example static or dynamic mixers.
• the second isocyanate group of for example 3(4)-isocyanatomethyl-l- methylcyclohexylisocyanate shows no reactivity relative to the polymer 's reactive group.
• a high selectivity as a result of the catalyst according to the invention results in minimum chain lengthening, in better flow properties of the powder paint and in the absence of unreacted diisocyanate after functionalisation.
• the weight ratio of the polymer and a compound containing two or more isocyanate groups with different reactivities is generally between 70 : 30 and 99 : 1, preferably between 70 : 30 and 97 : 3 and more in particular between 85 : 15 and 95 : 5.
• Different desired ratios may also be chosen.
• Usually at most one diisocyanate molecule will be used per reactive group of the polymer.
• the OH:NCO molar ratio is usually chosen so that this ratio lies between 1 : 0.3 and 1 : 3 and preferably between 1 : 0.5 and 1 : 2.5.
• the ratio is preferably between 1 : 0.8 and 1 : 1.2 and in the case of isocyanate-functional resins between 1 : 1.5 and 1 : 2.0
• thermosetting powder paints and chemical reactions for curing these powder paints into cured coatings are described in general terms in for example Misev, "Powder Coatings, Chemistry and Technology” (1991, John Wiley), pp. 44-54, pp. 148 and pp. 225-226 (and what is disclosed therein is included here by way of reference).
• the curing reaction between for example an IMCI-modified polymer and the crosslinker, as described in WO-A-95/20017, which results in the ultimate cured coating, will usually take place in the presence of an effective amount of catalyst. If the curing reaction is based on the reaction between isocyanate and groups that can react with isocyanate, use can be made of both the catalyst according to the invention and a different suitable catalyst. The importance of the ratio of the polymer and the crosslinker and of the amount of catalyst is explained in Misev, "Powder Coatings, Chemistry and Technology", pp. 174-223 (and what is disclosed therein is included here by way of reference).
• tertiary isocyanate-functionalised polymers are obtained.
• Such functional groups do not require a blocking agent because they have a relatively low reactivity towards a usual reactive component containing hydroxyl groups. That makes it possible for example to mix such polymers with a hydroxy-functional crosslinker in an extruder during the preparation of powder paint, without noticeable prereaction taking place.
• the crosslinker and the modified polymer can be mixed with one another with the aid of, for example, an extruder or a static mixer. It is, for example, possible to couple two static mixers in series, so that the polymer can be modified in the first mixer and the mixing with the crosslinker can take place in the second mixer.
• the two static mixers may differ in shape and/or they may be brought to different temperatures to enable control of the specific processes in the in-line mixers.
• reaction according to the invention by chemically curing into a powder coating for example a powder paint composition comprising a hydroxyl-functional polymer, IMCI as the crosslinker and the catalyst according to the invention.
• the temperature for this reaction is generally between 120°C and 200°C.
• Examples I-VI and Comparative Examples A-I 194 parts by weight of IMCI and 88 parts of neopentylalcohol (2,2-dimethylpropanol) were introduced into a glass flask. Next, 3 parts by weight of catalyst according to Table 1 were added to the stirred suspension, at room temperature. The changes in temperature during the exothermal reaction were followed with the aid of a thermometer. After 1 hour's reaction time a sample was taken and analysed by means of proton-NMR. The degree of conversion and the selectivity could be determined from the spectra obtained.
• the selectivity which was expressed in percents, represents the fraction of the most reactive isocyanate groups that have reacted with the equimolar amount of added alcohol to form a urethane group after full conversion of the alcohol. At 100% selectivity all the alcohol groups present reacted exclusively with the most reactive isocyanate groups; at 50% selectivity the added alcohol groups reacted with IMCI without discrimination between the different isocyanate groups.
• the detection limit for the selectivity according to this method lies at approx. 99 %. When little catalytic activity was observed, i.e. incomplete conversion after 1 hour's reaction time, this procedure was repeated after 20 hours.
• Example VIII Into a flask containing 1000 parts by weight of dry tetrahydrofuran and 2 parts by weight of zirconium (IV) acetylacetonate 154 parts by weight 1,4- diisocyanate-4-methylpentane DIMP and 45 parts by weight trimethylolpropane were introduced. The reaction mixture was stirred at reflux temperatur (65°C) for 4 hours. After cooling to room temperature 73 parts of diethylamine were introduced. After evaporation of the solvent a glassy material was obtained.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Inorganic Chemistry (AREA)
• Polyurethanes Or Polyureas (AREA)
• Organic Low-Molecular-Weight Compounds And Preparation Thereof (AREA)
• Catalysts (AREA)

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Citations (5)

• 1996
  • 1996-06-04 NL NL1003263A patent/NL1003263C2/nl not_active IP Right Cessation
• 1997
  • 1997-05-28 AU AU29161/97A patent/AU2916197A/en not_active Abandoned
  • 1997-05-28 JP JP10500440A patent/JP2000512540A/ja active Pending
  • 1997-05-28 WO PCT/NL1997/000300 patent/WO1997046517A1/en not_active Application Discontinuation
  • 1997-05-28 EP EP97923339A patent/EP0912500A1/en not_active Ceased
  • 1997-06-05 TW TW086107775A patent/TW334351B/zh active

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