Classifications

• • C—CHEMISTRY; METALLURGY
  • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
  • C09D—COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
  • C09D175/00—Coating compositions based on polyureas or polyurethanes; Coating compositions based on derivatives of such polymers
  • C09D175/04—Polyurethanes
  • C09D175/08—Polyurethanes from polyethers
• • 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
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/40—High-molecular-weight compounds
  • C08G18/62—Polymers of compounds having carbon-to-carbon double bonds
  • C08G18/6216—Polymers of alpha-beta ethylenically unsaturated carboxylic acids or of derivatives thereof
  • C08G18/622—Polymers of esters of alpha-beta ethylenically unsaturated carboxylic acids
  • C08G18/6225—Polymers of esters of acrylic or methacrylic acid
  • C08G18/6229—Polymers of hydroxy groups containing esters of acrylic or methacrylic acid with aliphatic polyalcohols
• • 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
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/40—High-molecular-weight compounds
  • C08G18/62—Polymers of compounds having carbon-to-carbon double bonds
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F2/00—Processes of polymerisation
  • C08F2/38—Polymerisation using regulators, e.g. chain terminating agents, e.g. telomerisation
• • 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
  • C08G18/28—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the compounds used containing active hydrogen
  • C08G18/40—High-molecular-weight compounds
  • C08G18/62—Polymers of compounds having carbon-to-carbon double bonds
  • C08G18/6216—Polymers of alpha-beta ethylenically unsaturated carboxylic acids or of derivatives thereof
  • C08G18/625—Polymers of alpha-beta ethylenically unsaturated carboxylic acids; hydrolyzed polymers of esters of these acids
  • C08G18/6254—Polymers of alpha-beta ethylenically unsaturated carboxylic acids and of esters of these acids containing hydroxy groups
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08L—COMPOSITIONS OF MACROMOLECULAR COMPOUNDS
  • C08L75/00—Compositions of polyureas or polyurethanes; Compositions of derivatives of such polymers
  • C08L75/04—Polyurethanes

Definitions

• the invention relates to the field of two-part polyurethane compositions.
• Two-part polyurethane is a well established technology for a variety of applications. Particularly known are two-part polyurethane compositions in which one part comprises polyol(s) and the second part comprises polyisocyanate(s).
• polyols a wide range of molecules is known, such as polyether polyols, polyester polyols and acrylic polyols.
• polyether polyols a wide range of molecules is known, such as polyether polyols, polyester polyols and acrylic polyols.
• These known two-part polyurethanes are particularly fast curing. Furthermore, they have also a short pot-life, which is problematic for certain applications, particularly for application of larger area of application. Furthermore, they also tend, unfortunately, to have a rather high viscosity after mixing. In order to reduce the viscosity additional solvents is used. However, this contravenes the trend of more stringent regulations in the market to ask for of a reduction of solvents or VOC (Volatile Organic Compounds) which is
• Hyperbranched polymers are a recently found class of polymers and could be obtained from different monomers having unsaturated C-C bonds. Hyperbranched polymers have a particular different structure than traditional polymers, particularly Polyols, which are either linear or only slightly branched. Hyperbranched polymers exhibit a branched structure. It is very advantageous that hyperbranched polymers can be made through one-pot synthesis and therefore are very cost effective.
• US 4,880,889 discloses a preparation of hydroxyl functional acrylic polymer with monomers having more than one C-C double bonds using a mercapto compound as chain stopper, being effectively a chain transfer agents for the radical polymerization process.
• US 5767211 discloses the preparation of (meth)acrylate functional hyperbranched polymers used for photopolymerization using a cobalt (II) complex as chain transfer catalyst.
• thermoformable cast being directly formed by the polymerization of different (meth)acrylic monomers in the presence of cobalt (II) complexes, particularly of a bis(borondifluoro-dimethylglyoximate) cobaltate (II) complex.
• cobalt (II) complexes particularly of cobalt (II) oxime complexes, and their use as chain transfer catalysts for free radical polymerization are disclosed in US 4,694,054 , A.Bakac et al., J. Am. Chem. Soc. 1984, 106, 5197-5202 and A.Bakac et al., J. Am. Chem. Soc. 2002, 124, 5616-5617 .
• US 5,115,064 discloses isocycanate functional acrylic copolymers being prepared from the free radical polymerization of isocyanatoalkyl esters of (meth)acrylic acid in the presence of mercapto compounds as regulators, which then in a second step may be crosslinked by polyols.
• the problem to be solved by the present invention is to offer a two-part polyurethane composition which has an extended pot-life on the one side but having a fast curing behaviour on the other side and which shows excellent UV stability.
• the present two-part composition after mixing has a relatively low viscosity, which leads relates to the advantages of either using less solvent or to increase the amount of fillers and, hence, still offer an acceptable workability.
• the two-part composition has -in comparison to corresponding two-part compositions according to the technology of the state of the art- an extend pot-life easily allowing also large area applications combined with a very fast cure.
• This is a rather exceptional behaviour as fast curing normally correlates also to short pot-life.
• the two-part polyurethane composition can be applied for a longer time on a surface, however, after the pot-life the development of strength is very rapid and high green strengths are obtained after very short time, particularly under heated conditions.
• This combination is particularly advantageous for application of the two-part polyurethane composition as a coating or an adhesive, particularly in application where the composition is applied on larger objects. It is also beneficial to users who apply and cure the coating in a production line such as automotive OEM coating application where the production time can be shortened and the heating energy can be reduced.
• the two-part polyurethane composition has an excellent UV stability which is not the case if a hyperbranched polyols being prepared by radical polymerization of the corresponding monomers using mercapto compounds as chain transfer agent would be used in the formulation instead.
• reaction product having pending NCO groups according to claim 16 can be easily prepared from the two-part polyurethane composition of invention and which has particular advantageous properties and is very interesting for the preparation of polyurethanes with very high mechanical properties.
• the present invention relates to two-part polyurethane composition.
• This two-part composition consists of a first pack ( C1 ) and of a second pack ( C2 ).
• the first pack ( C1 ) comprises at least one hyperbranched copolymer ( HBC ) having pending OH groups and which is prepared from at least
• the second pack ( C2 ) comprises at least one polyisocyanate ( PI ).
• polyisocyanate in the present document encompasses compounds having two or more isocyanate groups, independently of whether they are monomeric diisocyanates, oligomeric polyisocyanates, or polymers containing isocyanate groups and having a relatively high molecular weight (typically larger than 1000 g/mol).
• polymer in the present document encompasses on the one hand a collective of macromolecules which, while being chemically uniform, nevertheless differ in respect of degree of polymerization, molar mass, and chain length, and have been prepared by a polymerization reaction (chain-growth addition polymerization, polyaddition, polycondensation, radical polymerization).
• the term also, moreover, encompasses derivatives of such a collective of macromolecules from polymerization reactions, in other words compounds which have been obtained by means of reactions, such as additions or substitutions, for example, of functional groups on existing macromolecules, and which may be chemically uniform or chemically nonuniform.
• the term also encompasses, furthermore, what are known as prepolymers, by which are meant reactive oligomeric pre-adducts whose functional groups take part in the construction of macromolecules.
• substance names beginning with "poly”, such as polyisocyanate or polyol, denote substances which, in a formal sense, contain two or more of the functional groups which occur in their name per molecule.
• Root temperature means in the present document a temperature of 23°C.
• the first pack ( C1 ) (first component) comprises at least one hyperbranched copolymer ( HBC ) having pending OH groups.
• Said hyperbranched copolymer ( HBC ) having pending OH groups is prepared from at least one or more monomer(s) ( M2 ) having at least two unsaturated C-C bonds and one or more monomer(s) ( MH ) having one unsaturated C-C bonds and one hydroxyl group in the presence of a cobalt (II) complex ( CC ).
• Monomer(s) ( M2 ) having at least two unsaturated C-C bonds are in one embodiment particularly di(meth)acrylates which are (poly)alkylene or (poly)oxyalkylene bridged di(meth)acrylates.
• said di(meth)acrylate is of formula (I-a) or (I-b): wherein R 1 is H or a methyl group, preferably a methyl group; R 2 is a linear or branched alkylene group with 2 to 30 carbon atoms, particularly 2 to 15 carbon atoms, preferably an ethylene, propylene, isopropylene or butylene group; R 3 is a linear or branched alkylene group with 2 to 6 carbon atoms and n is an integer from 2 to 6.
• the alkylene group R 2 has some aromatic moieties in the backbone and the di(meth)acrylate is, hence, particularly of the formula (I-a') wherein R' and R" are H or CH 3 , R 5 and R 6 are independently from each other H, CH 3 or CH 2 CH 3 , n' is a value of 1 up to 6 and R 1 is as defined for formula (I-a), respectively (I-b).
• such monomers ( M2 ) having at least two unsaturated C-C bonds are bis(meth)acrylamides of diamines of the formula NH 2 -R 2 -NH 2 or NH 2 -[R 3 -O] n -R 3 -NH 2 wherein R 2 , R 3 and n are as defined for formula (I-a), respectively (I-b).
• such monomers ( M2 ) having at least two unsaturated C-C bonds are monomers having three or more, particularly three or four, unsaturated C-C bonds.
• monomer(s) ( M2 ) having at least two unsaturated C-C bonds are preferably monomer(s) having exactly two unsaturated C-C bonds.
• hydroxyalkyl(meth)acrylates Particularly useful as monomer(s) ( MH ) having one unsaturated C-C bonds and one hydroxyl group are hydroxyalkyl(meth)acrylates.
• hydroxyalkyl(meth)acrylates are the ones of formula (II) wherein R 1 is H or a methyl group, preferably a methyl group, and R 4 is a linear or branched alkylene group of 1 to 10 carbon atoms, particularly a methylene or ethylene or propylene or butylene group.
• Preferred such monomers are such as hydroxyethylacrylate (HEA), hydroxyethylmethacrylate, (HEMA),hydroxypropylacrylate (HPA), hydroxypropylmethacrylate (HPMA), hydroxybutylacrylate (HBA) or hydroxy-butylmethacrylate (HBMA).
• HAA hydroxyethylacrylate
• HEMA hydroxyethylmethacrylate
• HPMA hydroxypropylacrylate
• HPMA hydroxypropylmethacrylate
• HBA hydroxybutylacrylate
• HBMA hydroxy-butylmethacrylate
• monomer(s) having one unsaturated C-C bonds and two or more one hydroxyl group can be used as additional monomers.
• monomers are monoesters of (meth)acrylic acid and a polyol, such as (meth)acrylic monoester of glycerol or trimethylolpropane or trimethylolethane or pentaerythritol.
• monomer(s) having two or more unsaturated C-C bonds and at least one hydroxyl group can be used as additional monomers.
• monomers are diesters of (meth)acrylic acid and a triol or a tetrol such as trimethylolpropane di(meth)acrylate, trimethylolethane di(meth)-acrylate, glycerol di(meth)acrylate or pentaerythritol di(meth)acrylate or triesters of (meth)acrylic acid and a tetrol such as pentaerythritol tri(meth)acrylate.
• Such monomer(s) are obtained from the reaction of (meth)acrylic acid and a polyepoxide, such as the following formula: wherein R 1 , R' and R" are as defined for formula (I-a').
• monomer(s) ( M2 ) having at least two unsaturated C-C bonds and to monomer(s) ( MH ) having one unsaturated C-C bonds and one hydroxyl group, in further embodiments additional monomer(s) ( M1 ) having exactly one unsaturated C-C bonds may be used for the preparation for the hyperbranched copolymer ( HBC ).
• Such monomers ( M1 ) are preferably alkyl(meth)acrylates ( M1 ').
• Preferred alkyl(meth)acrylates are esters of (meth)acrylic acids and alkyl alcohols having 1 to 16, particularly 1 to 9 carbon atoms.
• the alkyl(meth)acrylate ( M1 ') is selected from the group consisting of methyl(meth)acrylate, ethyl(meth)acrylate, butyl(meth)acrylate, cyclohexyl-(meth)acrylate, hexyl(meth)acrylate, ethylhexyl(meth)acrylate isobornyl(meth)-acrylate, trimethylcyclohexyl(meth)acrylate, 2-ethylhexyl(meth)acrylate.
• esters of (meth)acrylic acid of monoalcohols having hetero atoms, particularly in form of ether groups, are suitable as monomer(s) having unsaturated C-C bonds are monomers ( M1 ), such as tetrahydrofurfuryl(meth)acrylate.
• styrene, butadiene or isoprene may be used in certain cases as monomers having one unsaturated C-C bonds.
• Particularly suitable monomers having unsaturated C-C bonds are acrylic acid, esters of acrylic acid, amides of acrylic acid, methacrylic acid, esters of methacrylic acid, amides of methacrylic acid.
• cobalt (II) complex CC
• cobalt (II) complexes serve as Chain Transfer Catalyst (CTC).
• cobalt (II) complexes are cobalt (II) porphyrin complexes or those cobalt(II) chelates disclosed in US 4,694,054 , which is incorporated herein by reference in their entirety.
• the cobalt (II) complex ( CC ) is particularly a cobaloxime.
• cobalt (II) complex CC
• cobalt(II) complexes of formula (III) and (III') are cobalt(II) complexes of formula (III) and (III').
• cobalt (II) complex ( CC ) is a bis(borondifluorodimethylglyoximate) cobaltate (II) complex.
• This Co (II) complex may be represented by the following formula (III').
• the cobalt (II) complex ( CC ), particularly the bis(borondifluoro-dimethylglyoximate) cobaltate (II) complex is preferably used in the preparation of the hyperbranched copolymer ( HBC ) in a concentration of less than 1 % by weight, particularly less than 0.5 % by weight, preferably of 0.001 to 0.1 % by weight, relative to the weight of the monomers having unsaturated C-C bonds.
• HBC hyperbranched polymers
• the production of the hyperbranched polymers ( HBC ) is made in the presence of a non-peroxide initiator ( IN ).
• a non-peroxide initiator particularly useful are azo initators such as 2,2'-azobis(2,4-dimethylvaleronitrile), 2,2-azobis-(4-methoxy-2,4-dimethylvaleronitrile), 2,2-azobis-(2,4-dimethylvaleronitrile), (1-phenylethyl)azodiphenylmethane, 2,2-azobis-(isobutyronitrile), dimethyl 2,2-azobis-(isobutyrate), 2,2-azobis-(2-methylbutyronitrile), 1,1-azobis-(1-cyclo-hexanecarbonitrile), 2,2-azobis-(2,4,4-trimethyl pentane), 2,2-azobis-2-methylpropane), 2,2-azobis(N,N-dimethylene isobutyronidine)dihydrochloride, 2,2-azobis
• hyperbranched copolymer ( HBC ) is prepared from
• hyperbranched copolymer ( HBC ) is prepared from
• azo initator particularly 2,2-azobis-(isobutyronitrile), and the cobalt (II) complex ( CC ).
• the hyperbranched copolymer ( HBC ) is prepared from
• azo initator particularly 2,2-azobis-(isobutyronitrile), and the cobalt (II) complex ( CC ).
• the polymerization reaction of the above composition(s) is typically carried out at high temperatures (60 - 400°C) by way of the addition of mixture of monomer(s)/CTC/initiator into a heated solvent at above mentioned high temperatures.
• the product obtained is generally a hyperbranched polymer in solution with relatively low viscosity and in high conversion of monomers (90-99%) with no gel.
• the resulted product, i.e. the hyperbranched polyol in the solvent has a typical viscosity ranging from 3'000 to 18'000 mPa ⁇ s (cP) at 20°C.
• the hyperbranched copolymer ( HBC ) having pending OH groups may be purified, however, it may also be used as such. In said resulted product, respectively in the hyperbranched copolymer ( HBC ) having pending OH groups, there may remain some residuals of the cobalt (II) complex ( CC ).
• polymerizations is conducted in 80 % by weight butyl acetate solution, to which a mixture of 3.2 % by weight of ethylene glycol dimethacrylate (EGDMA), 31 % by weight of methylmethacrylate (MMA), 28 % by weight of hydroxypropylmethacrylate (HPMA), 16 % by weight of butylmethacrylate (BMA), 1.2 % by weight of 2,2'-azobis(isobutyronitrile)(AIBN) and 45 ppm cobalt (II) complex ( CC ) is added over a period of time during which the temperature is maintained within 80-140°C. After the addition the mixture is stirred for a further period of time at above 60°C until the reaction is finished.
• EGDMA ethylene glycol dimethacrylate
• MMA methylmethacrylate
• HPMA hydroxypropylmethacrylate
• AIBN butylmethacrylate
• AIBN butylmethacrylate
• CC cobal
• the resulted product is cooled, filtered and ready to be used as a polyol component.
• the resulted product contains hyperbranched polyol in butyl acetate has a viscosity ranging from 3000 to 18000 mPa ⁇ s (cP) at 20°C.
• the first pack ( C1 ) may also comprise further ingredients which are principally known to the person skilled in the art in the field of two component polyurethanes.
• Particularly useful additional ingredients of the first pack are plasticizers, solvents, inorganic and organic fillers, catalysts, particularly for catalyzing the NCO/OH reaction, rheology modifiers, driers, adhesion promoters, stabilizers against heat, light and UV radiation, flame retardants, biocides, pigments or surface-active substances as for example wetting agents, flow control agents, de-aerating agents or defoamers.
• the second pack ( C2 ) (second component) comprises at least one polyisocyanate ( PI ).
• the polyisocyanate ( PI ) is a monomeric polyisocyanate ( PI-M ), particularly a monomeric diisocyanate or triisocyanate.
• Said monomeric polyisocyanate may be an aromatic or an aliphatic polyisocyanate.
• Aromatic polyisocyanate identifies an organic compound which contains exclusively aromatic isocyanate groups. "Aromatic” identifies an isocyanate group which is attached to an aromatic or heteroaromatic radical. "Aliphatic polyisocyanate” identifies an organic compound which contains aliphatic isocyanate groups. “Aliphatic” identifies an isocyanate group which is attached to an aliphatic, cycloaliphatic or arylaliphatic radical.
• suitable aromatic monomeric polyisocyanates include polyisocyanates such as 2,4- and 2,6-tolylene diisocyanate and any desired mixtures of these isomers (TDI), 4,4'-, 2,4'- and 2,2'-diphenylmethane diisocyanate and any desired mixtures of these isomers (MDI), 1,3- and 1,4-phenylene diisocyanate, 2,3,5,6-tetramethyl-1,4-diisocyanatobenzene, naphthalene-1,5-diisocyanate (NDI), 3,3'-dimethyl-4,4'-diisocyanatobiphenyl (TODI), dianisidine diisocyanate (DADI), 1,3,5-tris(isocyanatomethyl)benzene, tris(4-isocyanatophenyl)methane and tris-(4-isocyanatophenyl) thiophosphate.
• TDI 2,4- and 2,6
• polyisocyanate ( PI ) is an oligomeric polyisocyanate ( PI-O ) of the above mentioned monomeric polyisocyanates ( PI-M )
• Suitable oligomers of a monomeric diisocyanate include more particularly the oligomers of HDI, IPDI and TDI.
• such oligomers usually constitute mixtures of substances having different degrees of oligomerization and/or chemical structures. They preferably have an average NCO functionality of 2.1 to 4.0 and contain, more particularly isocyanurate groups, iminooxadiazinedione groups, uretdione groups, urethane groups, biuret groups, allophanate groups, carbodiimide groups, uretonimine groups or oxadiazinetrione groups. They preferably have a low monomeric diisocyanate content.
• HDI biurets for example Desmodur ® N 100 and Desmodur ® N 3200 (from Bayer), Tolonate ® HDB and Tolonate ® HDB-LV (from Perstorp) and also Duranate ® 24A-100 (from Asahi Kasei); HDI isocyanurates, examples being Desmodur ® N 3300, Desmodur ® N 3600 and Desmodur ® N 3790 BA (from Bayer), Desmodur ® N 3390 BA (from Bayer), Tolonate ® HDT, Tolonate ® HDT-LV and Tolonate ® HDT-LV2 (from Perstorp), (Duranate ® TPA-100 and Duranate ® THA-100 (from Asahi Kasei) and also Coronate ® HX (from Nippon Polyurethane); HDI uretdiones, an example being Desmodur ® N 3400 (from Bayer); HDI
• polyisocyanate ( PI ) is a polyurethane polymer ( PUP ) containing isocyanate groups.
• polyurethane polymer encompasses all polymers which are prepared by the process known as the diisocyanate polyaddition process. This also includes those polymers which are entirely or virtually free from urethane groups. Examples of polyurethane polymers are polyether-polyurethanes, polyester-polyurethanes, polyether-polyureas, polyureas, polyester-polyureas, polyisocyanurates and polycarbodiimides.
• One suitable polyurethane polymer is obtainable more particularly from the reaction of at least one polyol with at least one polyisocyanate, particularly with a monomeric polyisocyanates ( PI-M ) and/or an oligomeric polyisocyanate ( PI-O ) being both mentioned above.
• This reaction may involve the polyol and the polyisocyanate being reacted by customary methods, at temperatures, for example of 50°C to 100°C, optionally with accompanying use of suitable catalysts, the amount of the polyisocyanate being such that its isocyanate groups are present in a stoichiometric excess in relation to the hydroxyl groups of the polyol.
• the amount of the polyisocyanate is advantageously such that an NCO/OH ratio of 1.3 to 5, more particularly of 1.5 to 3, is observed.
• the "NCO/OH ratio” means the ratio of the number of isocyanate groups used to the number of hydroxyl groups used.
• the polyols which can be used for preparing a polyurethane polymer include, for example, the following commercially customary polyols or mixtures thereof:
• polyoxyalkylene diols or polyoxyalkylene triols are particularly polyoxyethylene and polyoxypropylene diols and triols.
• polyoxyalkylene diols and triols having a degree of unsaturation of less than 0.02 meq/g and having a molecular weight in the range of 1000 - 30 000 g/mol, and also polyoxypropylene diols and triols having a molecular weight of 400 - 8000 g/mol.
• ethylene oxide-terminated (“EO-end capped", ethylene oxide-end capped) polyoxypropylene polyols.
• EO-end capped ethylene oxide-end capped polyoxypropylene polyols.
• the latter are special polyoxypropylene-polyoxyethylene polyols which are obtained, for example, by further alkoxylating pure polyoxypropylene polyols, more particularly polyoxypropylene diols and triols, with ethylene oxide after the end of the polypropoxylation reaction, and as a result contain primary hydroxyl groups.
• These stated polyols preferably have an average molecular weight of 250 - 30 000 g/mol, more particularly of 400 - 20 000 g/mol, and preferably have an average OH functionality in the range from 1.6 to 3.
• Preferred polyols are polyether, polyester, polycarbonate and polyacrylate polyols, preferably diols and triols. Particularly preferred are polyether polyols, more particularly polyoxypropylene polyols and polyoxypropylene-polyoxyethylene polyols.
• the polyisocyanates ( PI ) are preferred to be oligomeric polyisocyanate ( PI-O ) or monomeric polyisocyanates ( PI-M ).
• the polyisocyanate ( PI ) has a molecular weight of less than 700g/mol, particularly of between 400 and 670 g/mol.
• the polyisocyanate ( PI ) is selected from the group consisting of 1,6-hexamethylene diisocyanate (HDI), 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate or IPDI), 2,4-toluene diisocyanate, 2,6-toluene diisocyanate and the isocyanurates or biurets or uretdiones thereof.
• HDI 1,6-hexamethylene diisocyanate
• IPDI isophorone diisocyanate
• IPDI isophorone diisocyanate
• 2,4-toluene diisocyanate 2,6-toluene diisocyanate
• isocyanurates or biurets or uretdiones thereof isocyanurates or biurets or uretdiones thereof.
• the second ( C2 ) may also comprise further ingredients which are principally known to the person skilled in the art in the field of 2 component polyurethanes.
• Particularly useful additional ingredients of the second pack are plasticizers, solvents, inorganic and organic fillers, such as catalysts, particularly for catalyzing the NCO/OH reaction, rheology modifiers, driers, adhesion promoters, stabilizers against heat, light and UV radiation, flame retardants, biocides, pigments or surface-active substances as for example wetting agents, flow control agents, de-aerating agents or defoamers.
• these optional ingredients should particularly not react with the other ingredients in said pack, particularly not with the polyisocyanate, or trigger some reaction of ingredients being present in the first pack.
• the two part polyurethane composition has low content of VOC (Volatile Organic Compounds) it is preferred that the first and/or the second pack has a very low content of, preferably no at all, solvent as additional ingredient in the two-part polyurethane composition.
• VOC Volatile Organic Compounds
• first pack and the second pack C2 are filled and stored in individual compartments, respectively packaging, to yield first pack ( C1 ), respectively second pack ( C2 ).
• compartments, respectively packaging are particularly in form of drums, pails, hobbocks, cartridge, bags, pouch, bucket or unipacks.
• the packaging, respectively so formed packs packs may also be attached to each others, typically in the form of twin cartridges (side-by-side arrangement) or cartridge-in-cartridge (co-central arrangement), which are usual packs, respectively packaging, for two part compositions.
• the first pack ( C1 ) and the second pack ( C2 ) as described are prepared separately from one another, and at least the second pack ( C2 ) in the absence of moisture.
• the two packs (components) are stable in storage separately from one another at room temperature or slightly elevated temperature. That is, they can each be kept in a suitable packaging or facility, as, for example, in a drum, a hobbock, a pouch, a bucket or a cartridge, for a period of several months up to a year or more prior to their application, without undergoing alteration in their respective properties to any extent relevant for their utility.
• the content of the first pack ( C1 ) and the content of the second pack ( C2 ) of the two-part polyurethane composition as disclosed above need to be mixed.
• the mixing ratio between the two packs ( C1 and C2 ) is preferably selected in such a ratio, that the amount of polyisocyanate (PI) is present in such an amount that the ratio of number hydroxyl groups being present in the first pack ( C1 ) to the number of isocyanate groups in the second pack ( C2 ) is a value between 0.9 and 1.1. This assures a fairly complete curing of the mixed two-part polyurethane composition.
• the disclosed two-part polyurethane composition can be broadly used, particularly as adhesive, sealant, primer, coating, paint or floor coating.
• the present invention relates, to a coating which is obtained by a procedure comprising the steps:
• the mixing of the two components may be done in one embodiment by metering the amount of content of the first and second pack ( C1 and C2 ) and mixing the two components by means application of a stirrer, a static or a dynamic mixer or by twin-feed spray technique in order to achieve a mixing quality being preferred as high as possible.
• the metering can be done either manually or automatically such as a metering pump or by coupled movement of pistons such as realized in a known twin cartridge system.
• Mixing may take place continuously or batchwise. If mixing takes place prior to application, it must be ensured that the time which elapses between the mixing of the two components ( C1 and C2 ) and the application is not too great, since otherwise there may be defects, such as a delayed or incomplete curing or incomplete development of adhesion to the surface of the solid, for example.
• the mixed two-part polyurethane composition may exhibit relatively low viscosity in comparison with analogous formulations using known polyols other than the hyperbranched copolymer ( HBC ) having pending OH groups being described above in detail. This allows on the one hand either to achieve better mixing quality, easier application or on the other hand to achieve a higher amount of filler to be used which results in a cheaper formulation. Finally lower viscosity also allows better sprayability and better film quality.
• HBC hyperbranched copolymer
• the mixed two-part polyurethane composition can be applied manually or automatically e.g. by means of a robot.
• the application of the two-part polyurethane composition can occur for example in the form of a spray, of a bead, by pouring, brushing, coating, spreading, scraping, wiping or dipping.
• suitable substrates ( S ) are, for example, inorganic substrates such as glass, glass ceramic, concrete, mortar, brick, tile, plaster, and natural stones such as granite or marble; metals or alloys such as aluminum, steel, nonferrous metals, galvanized metals; organic substrates such as leather, fabrics, paper, wood, resin-bound wood-based materials, resin-textile composites, plastics such as polyvinyl chloride (unplasticized and plasticized PVC), acrylonitrile-butadiene-styrene copolymers (ABS), SMC (sheet molding composites), polycarbonate (PC), polyamide (PA), polyesters, PMMA, polyesters, epoxy resins, polyurethanes (PUR), polyoxymethylene (POM), polyolefins (PO), especially polyethylene (PE) or polypropylene (PP) surface-treated by plasma, corona or flames, ethylene/propylene copolymers (EPM) and ethylene/propylene-diene terpol
• the substrates may where necessary be pretreated prior to application of the composition.
• pretreatments include in particular, physical and/or chemical cleaning processes, such as abrading, sandblasting, brushing or the like, for example, or treatment with cleaners or solvents or the application of an adhesion promoter, an adhesion-promoter solution or a primer.
• the composition begins to cure. It has been observed that the two-part polyurethane composition may cure very fast particularly under heated conditions in comparison to linear acrylic polyol systems.
• the two-part polyurethane composition has a series of different advantages such as combining low viscosity, long pot life, fast cure, advantageous adhesion properties, excellent weathering, UV and chemical resistance. Furthermore, it forms excellent films.
• the visual aspect of those films such as colour and gloss combined with good adhesion and scratch resistance and exceptional flexibility are very advantageous and particular important when using a two-part polyurethane composition for preparation of coatings.
• the present invention also relates to the use of the hyperbranched copolymer ( HBC ) having pending OH groups of a two-part polyurethane composition as described above for a as a non-crystallising curing agent for isocyanates. It is very advantages that such curing agents are not crystalline as this increases the quality of mixing and the rate of curing.
• the present invention relates also to a method of reacting the hyperbranched copolymer ( HBC ) having pending OH groups of a two-part composition as described above with at least one polyisocyanate characterized in that the hyperbranched copolymer ( HBC ) is brought in physical contact with the polyisocyanate.
• This contacting might be for example a simple or thorough mixing of the hyperbranched copolymer ( HBC ) and the polyisocyanate.
• HBC hyperbranched copolymer
• the polyisocyanate respectively a composition thereof
• a reaction can occur between the hyperbranched copolymer ( HBC ) and the polyisocyanate by simply contacting the two surfaces with each other.
• the reaction between the hyperbranched copolymer ( HBC ) having pending OH and at least one polyisocyanate leads to a reaction product.
• reaction product either exhibits some hydroxyl groups or some isocyanate groups.
• the reaction between the hyperbranched copolymer ( HBC ) having pending OH groups with at least one polyisocyanate is done in a such a ratio that the number of NCO groups of the polyisocyanate the number of OH groups of the hyperbranched copolymer ( HBC ) is ⁇ 1, particularly less than 0.5, preferably of 0.4 - 0.1, a relatively low viscous (despite the very high molecular weight) polyol having a very high OH functionality is obtained, basically being two hyperbranched polyol molecules being bridged by the polyisocyanate.
• Such polyols are suited well for getting polyurethanes of very high mechanical strength, particularly high stiffness and high glass transition temperatures.
• reaction between the hyperbranched copolymer ( HBC ) having pending OH groups with at least one polyisocyanate is done in a such a ratio that the number of NCO groups of the polyisocyanate the number of OH groups of the hyperbranched copolymer ( HBC ) is > 1, a reaction product having pending NCO groups ( HBC-NCO ) is obtained.
• Such reaction products represent a further aspect of the present invention.
• Particularly preferred are such polymers, in which all of the OH groups of the hyperbranched copolymer ( HBC ) are reacted by the polyisocyanates.
• the polyisocyanate does not crosslink individual hyperbranched copolymers which would lead fast to very high molecular weight.
• Such a reaction product having pending NCO groups represent low viscous polyisocyanates having a very high NCO functionality and hence is suited vey well as efficient crosslinker in polyurethane systems. Particularly, they yield polyurethane composition of extreme high mechanical properties, particularly high stiffness and high glass transition temperatures. Very unique properties are obtained in case if such a reaction product having pending NCO groups ( HBC-NCO ) is combined with polyurethane polymer ( PUP ) containing isocyanate groups which have been described above. In such system a synergistic effect of the properties of the elastic part stemming from the polyurethane (PUP) and the stiff part stemming from the reaction product ( HBC-NCO ) can be achieved. Particularly useful are these reaction products having pending NCO groups ( HBC-NCO ) in the field of coatings, particularly powder coatings.
• the first part (component) has been formed by mixing the polyol into the solvent followed by adding the Tinuvin ® additives and the tin catalyst.
• Catalyst levels are slightly different in order to make pot life and cure rates comparable.
• the Desmodur ® N 3390 BA was used as second part (component).
• the example Ref.1 is a reference example using a hyperbranched polyol using a mercapto compound as chain transfer catalyst.
• the reference examples Ref.2 to Ref.5 all use different traditional acrylic polyols being commercially available. All acrylic polyols are at 80% solids in butyl acetate. Table 2. Two-part compositions. 1 Ref.1 Ref.2 Ref.3 Ref.4 HPC-1 [g] 75 HP-Ref.
• the viscosity of the compositions was characterized directly after mixed by the determination of the flow time by use of flow cups.
• BS 3900 A6 No. 4 flow cups (according to ISO 2431) were used at room temperature for the mixed compositions and the flow time indicated in seconds in table 3.
• the initial viscosity ( ⁇ 0 ) was measured (in seconds) using the above flow cup method directly after mixing. Further measurements of viscosity ( ⁇ x ) were undertaken after different times (t x ) after mixing. As pot life that time was identified for which the viscosity ( ⁇ x ) is the double (in seconds) of the initial viscosity ( ⁇ 0 ). Long pot life is always useful for formulators for the convenience of application.
• Films of mixed compositions were casted (100 micron wet film thickness) using a 100 micron draw down bar (Sheen Wire Bar Coater 1120/25/100) on a Q-Panel (A-36 aluminium panels (76x152x0.625 mm) supplied by Q-Lab).
• the solvent was allowed to evaporate in a fume cupboard for 30 minutes before being cured in the oven (80°C) for 5 minutes, resp. 30 minutes, or in air (at room temperature) for 6 hours, resp. 24 hours, resp. 7 days.
• the hardness of the films was followed using a Persoz pendulum hardness test equipment. A measure for the hardness was hence the time (in seconds) of swinging amplitude to decrease from 12° to 4°.
• the UV-stability was assessed by means of QUV-A weathering stability test method.
• the panels were allowed to cure for at least 21 days before subjecting to QUV test.
• Ref.1 formulation had the longest pot life whilst the 1 had the second longest pot life.
• the time until they have reached the same viscosity level than the other examples is even longer, resulting in a much longer workability.
• the values of hardness show that the examples 1 and Ref. 1 -despite the extended pot-life - develop very fast a high hardness that as well at 80°C (Hardness 5min at 80°C) as at room temperature (Hardness 6 hr at 23°C) as compared as to the composition using the conventional polyols.
• the hardness obtained on long term curing is, however, more or less at a comparable level.

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• 2010
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• 2011
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