WO2007081844A2 - Compositions d'enrobage liquides non aqueuses - Google Patents

Compositions d'enrobage liquides non aqueuses Download PDF

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Publication number
WO2007081844A2
WO2007081844A2 PCT/US2007/000356 US2007000356W WO2007081844A2 WO 2007081844 A2 WO2007081844 A2 WO 2007081844A2 US 2007000356 W US2007000356 W US 2007000356W WO 2007081844 A2 WO2007081844 A2 WO 2007081844A2
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WO
WIPO (PCT)
Prior art keywords
diisocyanate
diol
mol
polyurethane resin
diols
Prior art date
Application number
PCT/US2007/000356
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English (en)
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WO2007081844A3 (fr
Inventor
Carmen Flosbach
Olaf Ley
Tanja Renkes
Original Assignee
E. I. Du Pont De Nemours And Company
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Publication of WO2007081844A2 publication Critical patent/WO2007081844A2/fr
Publication of WO2007081844A3 publication Critical patent/WO2007081844A3/fr

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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
    • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
    • C08G18/703—Isocyanates or isothiocyanates transformed in a latent form by physical means
    • C08G18/705—Dispersions of isocyanates or isothiocyanates in a liquid medium
    • C08G18/707—Dispersions of isocyanates or isothiocyanates in a liquid medium the liquid medium being a compound containing active hydrogen not comprising water
    • 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
    • C08G18/80—Masked polyisocyanates
    • C08G18/8003—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen
    • C08G18/8006—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen with compounds of C08G18/32
    • C08G18/8009—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen with compounds of C08G18/32 with compounds of C08G18/3203
    • C08G18/8012—Masked polyisocyanates masked with compounds having at least two groups containing active hydrogen with compounds of C08G18/32 with compounds of C08G18/3203 with diols
    • C08G18/8016—Masked aliphatic or cycloaliphatic polyisocyanates
    • 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

Definitions

  • the invention relates to novel non-aqueous, liquid coating compositions which contain binders that are cross-linkable by polyisocyanate and isocyanate-functional polyurethane resin as cross- linking agent.
  • Non-aqueous, liquid coating compositions based on binders cross- linkable by polyisocyanate, in particular hydroxyl-fu notional binders, and polyisocyanate cross-linking agents are known. Examples are corresponding two-component coating systems (c.f. European Coatings Handbook, Curt R. Vincentz Verlag, Hannover, 2000, page 66).
  • the per se known non-aqueous, liquid coating compositions based on binders cross-linkable by polyisocyanate, in particular hydroxyl-functional binders, and free, i.e., unblocked polyisocyanate cross-linking agents may be improved if they contain, instead of the hitherto conventional polyisocyanate cross-linking agents, a specific kind of isocyanate-functional polyurethane resin as the only free polyisocyanate component. It is, for example, possible to achieve a high solids content of the coating compositions, favorable sagging properties (even at elevated temperatures) and good technological properties, in particular, good stone chip resistance and good scratch resistance, of the coating layers produced with the coating compositions. In particular, a longer pot and processing life of the coating compositions can be achieved than is normally usual for two-component coating systems consisting of an isocyanate-reactive binder component and a free polyisocyanate crosslinker component.
  • the invention is directed to non-aqueous, liquid coating compositions which contain at least one isocyanate-functional polyurethane resin A as the only polyisocyanate component and at least one binder B with groups reactive with the isocyanate groups of A, wherein the at least one polyurethane resin A is present as particles having a melting temperature of 40 to 180 0 C, in particular, 60 to 160 0 C.
  • the coating compositions according to the invention are liquid, contain organic solvent(s) inert with isocyanate groups and have a solids content of, for example, 40 to 85 wt.%, preferably of 45 to 75 wt.%.
  • the solids content of the coating compositions according to the invention consists of the resin solids content and the following optional components: pigments, fillers (extenders) and non-volatile additives.
  • the resin solids content of the coating compositions according to the invention comprises the at least one isocyanate-functional polyurethane resin A and the binder solids content comprising the at least one binder B.
  • the resin solids content of the coating compositions according to the invention consists of 10 to 80 wt.% of the at least one polyurethane resin A, 20 to 90 wt.% of the at least one binder B and 0 to 30 wt.% of one or more components C, wherein the weight percentages add up to 100 wt.%.
  • the resin solids content does not comprise any component(s) C and that it consists of 10 to 80 wt.%, preferably 20 to 80 wt.% of the at least one polyurethane resin A and 20 to 90 wt.%, preferably 20 to 80 wt.% of the binder solids content consisting of one or more binders B, wherein the weight percentages add up to 100 wt.%.
  • the polyurethane resins A are resins with free isocyanate groups. They are present in the coating compositions according to the invention as particles, in particular with a non-spherical shape, and have a melting temperature of 40 to 180 0 C, in particular 60 to 160 0 C.
  • the melting temperatures are not in general sharp melting points, but instead the upper end of melting ranges with a breadth of, for example, 30 to 150 0 C.
  • the melting ranges and thus the melting temperatures may be determined, for example, by DSC (differential scanning calorimetry) at heating rates of 10 K/min.
  • the polyurethane resins A have isocyanate contents of, for example, 2 to 13.4 wt.-% (calculated as NCO, molar mass 42).
  • the polyurethane resins A are insoluble or virtually insoluble in the coating compositions and are present therein as particles.
  • the polyurethane resins A are only very slightly, if at all, soluble in organic solvents conventional in coatings, the solubility amounting, for example, to less than 10, in particular less than 5 g per litre of butyl acetate at 20 0 C.
  • isocyanate-functional polyurethane resins is known to the person skilled in the art; in particular, they may be produced by reacting polyol(s) with polyisocyanate(s) in the excess.
  • Polyols suitable for the production of the polyurethane resins A are not only polyols in the form of low molar mass compounds defined by empirical and structural formula but also oligomeric or polymeric polyols with number-average molar masses of, for example, up to 800, for example, corresponding hydroxyl-functional polyethers, polyesters or polycarbonates; low molar mass polyols defined by an empirical and structural formula are, however, preferred.
  • the isocyanate-functional polyurethane resins A may be produced in the presence of organic solvents inert towards isocyanate groups, which, however, makes it necessary to isolate the polyurethane resins A obtained in this manner or remove the solvent therefrom.
  • the production of the polyurethane resins A is, however, carried out without solvent and without subsequent purification operations.
  • the polyurethane resins A are polyurethane diisocyanates which can be prepared by reacting 1 ,6-hexane diisocyanate with a diol component in the molar ratio (x+1) : x, wherein x means any desired value from 2 to 6, preferably, from 2 to 4, and the diol component is one single diol, in particular, one single (cyclo)aliphatic diol with a molar mass in the range of 62 to 600, or a combination of diols, preferably two to four, in particular, two or three diols, wherein in the case of a diol combination each of the diols preferably constitutes at least 10 mol % of the diols of the diol component.
  • the diols are (cyclo)aliphatic diols, each with a molar mass in the range of 62 to 600.
  • (cyclo)aliphatic used in the present description and the claims encompasses cycloaliphatic, linear aliphatic, branched aliphatic and cycloaliphatic with aliphatic residues.
  • Diols differing from (cyclo)aliphatic diols may furthermore comprise oligomeric or polymeric diols with number-average molar masses of, for example, up to 800, for example, corresponding polyether, polyester or polycarbonate diols.
  • the production of the polyurethane diisocya nates can be carried out in the presence of organic solvent inert towards isocyanate groups, followed by isolation of the polyurethane diisocyanates so prepared.
  • the production of the polyurethane diisocyanates is carried out without solvent and without subsequent purification operations.
  • x means any desired value from 2 to 6, preferably from 2 to 4.
  • One single diol, in particular, one single (cyclo)aliphatic diol with a molar mass in the range of 62 to 600 is used as the diol component.
  • each of the diols preferably constitutes at least 10 mol % of the diols of the diol component and wherein it is further preferred, that at least 70 mol %, in particular 100 mol % of the diols are (cyclo)aliphatic diols, each with a molar mass in the range of 62 to 600.
  • the diol component may be introduced as a mixture of its constituent diols or the diols constituting the diol component may be introduced individually into the synthesis. It is also possible to introduce a proportion of the diols as a mixture and to introduce the remaining proportion(s) in the form of pure diol.
  • diols which are possible as one single diol of the diol component are ethylene glycol, the isomeric propane- and butanediols, 1 ,5-pentanediol, 1 ,6-hexanediol, 1 ,10-decanediol, 1 ,12-dodecanediol, 1 ,4- cyclohexanedimethanol, hydrogenated bisphenol A and dimer fatty alcohol.
  • diols which are possible as constituent of the diol component are telechelic (meth)acrylic polymer diols, polyester diols, polyether diols, polycarbonate diols, each with a number-average molar mass of, for example, up to 800 as representatives of oligomeric or polymeric diols, bisphenol A as a representative of low molar mass non- (cyclo)aliphatic diols defined by empirical and structural formula and ethylene glycol, the isomeric propane- and butanediols, 1 ,5-pentanediol, 1 ,6-hexanediol, 1 ,10-decanediol, 1 ,12-dodecanediol, neopentyl glycol, butylethylpropanediol, the isomeric cyclohexanediols, the isomeric cyclohexanedimethanol
  • 1 ,6-hexane diisocyanate and the diol component are preferably reacted together in the absence of solvents.
  • the reactants may here all be reacted together simultaneously or in two or more synthesis stages. When the synthesis is performed in multiple stages, the reactants may be added in the most varied order, for example, also in succession or in alternating manner.
  • the diol component may, for example, be divided into two or more portions or into individual diols, for example, such that 1 ,6- hexane diisocyanate is initially reacted with part of the diol component before further reaction with the remaining proportion of the diol component.
  • the individual reactants may in each case be added in their entirety or in two or more portions.
  • the reaction is exothermic and proceeds at a temperature above the melting temperature of the reaction mixture.
  • the reaction temperature is, for example, 60 to 200 0 C.
  • the rate of addition or quantity of reactants added is accordingly determined on the basis of the degree of exothermy and the liquid (molten) reaction mixture may be maintained within the desired temperature range by heating or cooling.
  • the polyurethane diisocyanates assume the form of a mixture exhibiting a molar mass distribution.
  • the polyurethane diisocyanates do not, however, require working up and may be used directly as isocyanate- functional polyurethane resins A.
  • the polyurethane resins A are polyurethane diisocyanates which can be prepared by reacting a diisocyanate component and a diol component in the molar ratio (x+1 ) : x, wherein x means any desired value from 2 to 6, preferably, from 2 to 4, wherein 50 to 80 mol % of the diisocyanate component is formed by 1 ,6- hexane diisocyanate, and 20 to 50 mol % by one or two diisocyanates, each forming at least 10 mol % of the diisocyanate component and being selected from the group consisting of toluylene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, trimethylhexane diisocyanate, cyclohexane diisocyanate, cyclohexanedimethylene diisocyanate and
  • the production of the polyurethane diisocyanates can be carried out in the presence of organic solvent inert towards isocyanate groups, followed by isolation of the polyurethane diisocyanates so prepared.
  • the production of the polyurethane diisocyanates is carried out without solvent and without subsequent purification operations.
  • the diisocyanate component and the diol component are reacted stoichiometrically with one another in the molar ratio (x+1 ) mol diisocyanate : x mol diol, wherein x represents any value from 2 to 6, preferably from 2 to 4.
  • 50 to 80 mol % of the diisocyanate component is formed by 1 ,6- hexane diisocyanate, and 20 to 50 mol % by one or two diisocyanates selected from the group consisting of toluylene diisocyanate, diphenylmethane diisocyanate, dicyclohexylmethane diisocyanate, isophorone diisocyanate, trimethylhexane diisocyanate, cyclohexane diisocyanate, cyclohexanedimethylene diisocyanate and tetramethylenexylylene diisocyanate, wherein if two diisocyanates are selected, each diisocyanate forms at least 10 mol % of the diisocyanates of the diisocyanate component.
  • the diisocyanate or the two diisocyanates are selected from dicyclohexylmethane diisocyanate, isophorone diisocyanate, trimethylhexane diisocyanate, cyclohexane diisocyanate, cyclohexanedimethylene diisocyanate and tetramethylenexylylene diisocyanate.
  • the diol component consists to an extent of 20 to 100 mol% of at least one linear aliphatic alpha,omega-C2-C12-diol and to an extent of 0 to 80 mol% of at least one diol differing from linear aliphatic alpha, omega-C2- C12-diols.
  • the diol component preferably consists of no more than four different diols, in particular only of one to three diols. In the case of only one diol, it accordingly comprises a linear aliphatic alpha,omega-C2-C12- diol.
  • the diol component consists to an extent of 20 to 100 mol%, preferably of 80 to 100 mol%, of at least one linear aliphatic alpha,omega-C2-C12-diol and to an extent of 0 to 80 mol%, preferably of 0 to 20 mol% of at least one diol differing from linear aliphatic alpha,omega-C2-C12-diols and preferably, also from alpha.omega-diols with more than 12 carbon atoms.
  • the at least one diol differing from linear aliphatic alpha,omega-C2-C12-diols and preferably, also from alpha.omega-diols with more than 12 carbon atoms comprises in particular (cyclo)aliphatic diols defined by empirical and structural formula and with a low molar mass in the range of 76 to 600.
  • the proportion of possible non-(cyclo)aliphatic diols preferably amounts to no more than 30 mol% of the diols of the diol component.
  • each diol preferably makes up at least 10 mol% of the diol component.
  • the diol component does not comprise any non- (cyclo)aliphatic diols. Most preferably, it does not comprise any diols that are different from linear aliphatic alpha,omega-C2-C12-diols, but rather consists of one to four, preferably, one to three, and in particular, only one linear aliphatic alpha,omega-C2-C12-diol.
  • the diol component may be introduced as a mixture of its constituent diols or the diols constituting the diol component may be introduced individually into the synthesis. It is also possible to introduce a proportion of the diols as a mixture and to introduce the remaining proportion(s) in the form of pure diol.
  • linear aliphatic alpha,omega-C2-C12-diols that may be used as one single diol or as constituent of the diol component are ethylene glycol, 1 ,3-propanediol, 1 ,4-butanediol, 1 ,5-pentanediol, 1 ,6- hexanediol, 1 ,10-decanediol and 1 ,12-dodecanediol.
  • diols that are different from linear aliphatic alpha,omega-C2-C12-diols and may be used in the diol component are telechelic (meth)acrylic polymer diols, polyester diols, polyether diols, polycarbonate diols, each with a number-average molar mass of, for example, up to 800 as representatives of oligomeric or polymeric diols, bisphenol A as a representative of low molar mass non-(cyclo)aliphatic diols defined by empirical and structural formula and those isomers of propanediol and butanediol that are different from the isomers of propanediol and butanediol specified in the preceding paragraph, as well as, neopentyl glycol, butyl ethyl propanediol, the isomeric cyclohexanediols, the isomeric cyclohexanedimethanols
  • the diisocyanates of the diisocyanate component and the diol component are preferably reacted together in the absence of solvents.
  • the reactants may here all be reacted together simultaneously or in two or more synthesis stages. When the synthesis is performed in multiple stages, the reactants may be added in the most varied order, for example, also in succession or in alternating manner.
  • the diol component may, for example, be divided into two or more portions or into individual diols, for example, such that the diisocyanates are initially reacted with part of the diol component before further reaction with the remaining proportion of the diol component.
  • the diisocyanate component may also be divided into two or more portions or into the individual diisocyanates, for example, such that the hydroxyl components are initially reacted with part of the diisocyanate component and finally with the remaining proportion of the diisocyanate component.
  • the individual reactants may in each case be added in their entirety or in two or more portions.
  • the reaction is exothermic and proceeds at a temperature above the melting temperature of the reaction mixture.
  • the reaction temperature is, for example, 60 to 200 0 C.
  • the rate of addition or quantity of reactants added is accordingly determined on the basis of the degree of exothermy and the liquid (molten) reaction mixture may be maintained within the desired temperature range by heating or cooling.
  • solid polyurethane diisocyanates are obtained.
  • low molar mass diols defined by empirical and structural formula are used for synthesis of the polyurethane diisocyanates, their calculated molar masses are in the range of 625 or above, for example, up to 2300.
  • the polyurethane diisocyanates assume the form of a mixture exhibiting a molar mass distribution.
  • the polyurethane diisocyanates do not, however, require working up and may be used directly as isocyanate- functional polyurethane resins A.
  • the polyurethane resins A are polyurethane polyisocyanates which can be prepared by reacting a trimer of a (cyclo)aliphatic diisocyanate, 1 ,6-hexanediisocyanate and a dio!
  • x means any desired value from 1 to 6, preferably, from 1 to 3, wherein the diol component is one single linear aliphatic alpha, omega C2-C12 diol or a combination of two to four, preferably, two or three, (cyclo)aliphatic diols, wherein in the case of diol combination, each of the diols makes up at least 10 mol % of the diols of the diol combination and the diol combination consists of at least 80 mol % of at least one linear aliphatic alpha.omega C2-C12 diol.
  • trimer of the (cyclo)aliphatic diisocyanate, 1 ,6- hexanediisocyanate and the diol component are reacted stoichiometrically with one another in the molar ratio 1 mol trimer of the (cyclo)aliphatic diisocyanate : x mol 1 ,6-hexanediisocyanate : x mol diol, wherein x represents any value from 1 to 6, preferably from 1 to 3.
  • trimer of the (cyclo)aliphatic diisocyanate is polyisocyanates of the isocyanurate type, prepared by trimerization of a (cyclo)aliphatic diisocyanate.
  • Appropriate trimerization products derived, for example, from 1 ,4-cyclohexanedimethylenediisocyanate, in particular, from isophorondiisocyanate and more particularly, from 1 ,6- hexanediisocyanate, are suitable.
  • the industrially obtainable isocyanurate polyisocyanates generally contain, in addition to the pure trimer, i.e., the isocyanurate made up of three diisocyanate molecules and comprising three NCO functions, isocyanate-functional secondary products with a relatively high molar mass. Products with the highest possible degree of purity are preferably used.
  • trimers of the (cyclo)aliphatic diisocyanates obtainable in industrial quality are regarded as pure trimer irrespective of their content of said isocyanate-functional secondary products with respect to the molar ratio of 1 mol trimer of the (cyclo)aliphatic diisocyanate : x mol 1 ,6-hexanediisocyanate : x mol diol.
  • One single linear aliphatic alpha.omega C2-C12 diol or combinations of two to four, preferably of two or three, (cyclo)aliphatic diols are used as the diol component.
  • the diol combination preferably consists of two to four, in particular two or three, linear aliphatic alpha.omega C2-C12 diols.
  • Examples of one single linear aliphatic alpha.omega C2-C12 diol or linear aliphatic alpha.omega C2-C12 diols which can be used within the diol combination are ethylene glycol, 1 ,3-propanediol, 1 ,4-butanediol, 1 ,5- pentanediol, 1 ,6-hexanediol, 1 ,10-decanediol, 1 ,12-dodecanediol.
  • Examples of (cyclo)aliphatic diols which can be used within the diol combination in addition to the at least one linear aliphatic alpha.omega C2- C12 diol making up at least 80 mol % of the diol combination are the further isomers of propane and butane diol, different from the isomers of propane and butane diol cited in the preceding paragraph, and neopentylglycol, butylethylpropanediol, the isomeric cyclohexane diols, the isomeric cyclohexanedimethanols, hydrogenated bisphenol A and tricyclodecanedimethanol.
  • the mixture of the diols making up the combination can be used in the synthesis process or the diols making up the diol combination are each used individually in the synthesis. It is also possible to use a portion of the diols as a mixture and the remaining fraction(s) in the form of pure diol.
  • preferred diol combinations totalling 100 mol % in each case are combinations of 10 to 90 mol % 1,3- propanediol with 90 to 10 mol % 1 ,5-pentanediol, 10 to 90 mol % 1 ,3- propanediol with 90 to 10 mol % 1 ,6-hexanediol and 10 to 90 mol % 1 ,5- pentanediol with 90 to 10 mol % 1 ,6-hexanediol.
  • the trimer of the (cyclo)aliphatic diisocyanate, 1 ,6-hexane- diisocyanate and the diol component are preferably reacted together in the absence of solvents.
  • the reactants may here all be reacted together simultaneously or in two or more synthesis stages. Synthesis procedures in which the diol component and the trimer of the (cyclo)aliphatic diisocyanate alone are reacted with one another are preferably avoided. When the synthesis is performed in multiple stages, the reactants may be added in the most varied order, for example, also in succession or in alternating manner.
  • 1 ,6-hexanediisocyanate may be reacted initially with the diol component and then with the trimer of the (cyclo)aliphatic diisocyanate or a mixture of the isocyanate-functional components with the diol component.
  • the diol component may, for example, also be divided into two or more portions, for example, also into the individual (cyclo)aliphatic diols.
  • the individual reactants may in each case be added in their entirety or in two or more portions.
  • the reaction is exothermic and proceeds at a temperature above the melting temperature of the reaction mixture.
  • the reaction temperature is, for example, 60 to 200 0 C.
  • the rate of addition or quantity of reactants added is accordingly determined on the basis of the degree of exothermy and the liquid (molten) reaction mixture may be maintained within the desired temperature range by heating or cooling.
  • solid polyurethane polyisocyanates with number average molar masses in the range of 1 ,500 to 4,000 are obtained.
  • the polyurethane polyisocyanates do not require working up and may be used directly as isocyanate-functional polyurethane resins A.
  • the at least one isocyanate-functional polyurethane resin A is present in particulate form, in particular in the form of particles with a non- spherical shape, in the coating compositions.
  • the average particle size (mean particle diameter) of the polyurethane resin A particles determined by means of laser diffraction is, for example, 1 to 100 ⁇ m.
  • the polyurethane resin A particles may be formed by grinding (milling) of the solid polyurethane resin(s) A; for example, conventional powder coat production technology may be used for that purpose.
  • the polyurethane resin A particles may either be stirred or mixed as a ground powder into the per se liquid coating composition or liquid constituents thereof, wherein it is possible subsequently to perform additional wet grinding or dispersing of the polyurethane resin A particles, for example, by means of a bead mill, in the resultant suspension.
  • a further method for forming the polyurethane resin A particles involves hot dissolution of the at least one polyurethane resin A in an organic solvent (mixture) inert towards isocyanate groups and subsequent polyurethane resin A particle formation during and/or after cooling, in particular, dissolving the at least one polyurethane resin A in a proportion or the entirety of the solvent (mixture) with heating to the melting temperature or above, for example, to temperatures of 40 to above 18O 0 C, whereupon the polyurethane resin A particles may form during and/or after the subsequent cooling. Thorough mixing or stirring is preferably performed during cooling.
  • polyurethane resin A particles with average particle sizes at the lower end of the range of average particle sizes, for example, in the range of 1 to 50 ⁇ m, in particular 1 to 30 ⁇ m.
  • the coating compositions according to the invention contain at least one binder B with groups reactive with the isocyanate groups of the at least one polyurethane resin A, for example, groups containing active hydrogen.
  • the binder(s) B are not solid at room temperature but are, for example, liquid, and/or are soluble in an organic solvent (mixture). Binders B soluble in an organic solvent (mixture) are present in dissolved form in the coating compositions containing organic solvent(s).
  • the binders B in particular comprise conventional hydroxyl- functional binders. Binders B with hydroxy! groups which may be considered are conventional hydroxyl-fu notional binders known to the person skilled in the art.
  • the molar ratio of groups reactive with isocyanate groups, in particular hydroxyl groups, from the at least one binder B to the isocyanate groups from the at least one polyurethane resin A is, for example, 0.5 : 1 to 3 : 1 , in particular 0.7 : 1 to 2 : 1.
  • the coating compositions according to the invention may contain one or more components C which contribute towards the resin solids content.
  • components C means components free of groups which are reactive with isocyanate groups, such as, in particular, hydroxyl groups, and also free of isocyanate groups.
  • the components C comprise in particular corresponding resins and/or crosslinking agents.
  • type C resins are physically drying resins or resins which may be chemically cured by reactions other than the addition of groups reactive with isocyanate groups, such as, in particular, hydroxyl groups, onto isocyanate groups.
  • type C crosslinking agents are, in particular, conventional crosslinking agents known to the person skilled in the art, in particular, for coating systems based on hydroxyl-functional binders, such as, for example, transesterification crosslinking agents; blocked polyisocyanate crosslinking agents; aminoplast resin crosslinking agents, such as, melamine-formaldehyde resins; and/or trisalkoxycarbonylaminotriazine crosslinking agents.
  • One, some or each of components A, B and C may contain free- radically polymerizable olefinic double bonds.
  • the coating compositions according to the invention may then be cured not only by the reaction of the isocyanate groups of the at least one polyurethane resin A with the groups of the binder(s) B which are reactive with isocyanate groups, but additionally by free-radical polymerization of the olefinic double bonds, in particular, by photochemically induced free-radical polymerization.
  • Such compositions are also known as "dual-cure" coating compositions.
  • the coating compositions according to the invention have a solids content of, for example, 40 to 85 wt.%, preferably 45 to 75 wt.%.
  • the organic solvent content is, for example, 15 to 60 wt.%, preferably 25 to 55 wt.%; the sum of the wt.-% of the solids content and the organic solvent content is here, for example, 90 to 100 wt.-% (any possible difference in the corresponding range of above 0 to 10 wt.-% to make up to the total of 100 wt.% is in general formed by volatile additives).
  • the coating compositions preferably contain no or only small proportions of isocyanate-reactive organic solvents, for example, less than 10 wt.%, relative to the entire organic solvent.
  • the organic solvents are in particular conventional coating solvents, for example, glycol ethers, such as, dipropylene glycol dimethyl ether, dipropylene glycol monomethyl ether, ethylene glycol dimethylether; glycol ether esters, such as, ethyl glycol acetate, butyl glycol acetate, butyl diglycol acetate, methoxypropyl acetate; esters, such as, butyl acetate, isobutyl acetate, amyl acetate; ketones, such as, methyl ethyl ketone, methyl isobutyl ketone, diisobutyl ketone, cyclohexanone, isophorone; N-alkyl pyrrolidones, such as, N-methyl pyrrolidone; aromatic hydrocarbons, such as, xylene, Solvesso® 100 (mixture of aromatic hydrocarbons with a boiling range from 155°C to 185°C), So
  • the coating compositions may contain further conventional coating additives, for example, inhibitors, catalysts, levelling agents, wetting agents, anticratering agents, antioxidants and/or light stabilizers.
  • the additives are used in conventional amounts known to the person skilled in the art.
  • photoinitiators are contained in general.
  • the coating compositions may also contain transparent pigments, color-imparting and/or special effect-imparting pigments and/or fillers, for example, corresponding to a ratio by weight of pigment plus filler : resin solids content in the range from 0:1 to 2:1.
  • Suitable color-imparting pigments are any conventional coating pigments of an organic or inorganic nature.
  • inorganic or organic color-imparting pigments are titanium dioxide, iron oxide pigments, carbon black, azo pigments, phthalocyanine pigments, quinacridone pigments and pyrrolopyrrole pigments.
  • special effect pigments are metal pigments, for example, of aluminum, copper or other metals, interference pigments, such as, for example, metal oxide-coated metal pigments, for example, iron oxide-coated aluminum, coated mica, such as, for example, titanium dioxide-coated mica, graphite effect-imparting pigments, iron oxide in flake form, liquid crystal pigments, coated aluminum oxide pigments and coated silicon dioxide pigments.
  • fillers are silicon dioxide, aluminum silicate, barium sulfate, calcium carbonate and talc.
  • the long pot and processing life of the coating compositions according to the invention is particularly advantageous.
  • Conventional coating compositions based on hydroxyl-functional binders and free polyisocyanate crosslinking agents are in fact distinguished by only limited pot and processing life and, even before such coating compositions are used as directed, a rapid reaction occurs between the hydroxyl-functional binder and the polyisocyanate crosslinking agent, which is perceptible, for example, from an increase in the viscosity of the coating composition.
  • Such coating compositions must accordingly be formulated and stored as a two-component system, i.e., the component containing hydroxyl- ' functional binder and the component containing free polyisocyanate can be mixed with one another only shortly or directly before application of the coating composition; the sum of pot life plus processing life of such coating compositions after the components have been mixed amounts, for example, to only up to 4 hours.
  • the pot and processing life is substantially longer in case of the coating compositions according to the invention; the sum of pot life plus processing life after mixing (when A and B are brought into contact) amounts, for example, to up to 24 hours.
  • the coating compositions may be used for the production of single- layer coatings or for the production of one or more coating layers within a multilayer coating, such as, in particular, an automotive multilayer coating, either on an automotive body or on an automotive body part. This may relate to both original and repair coating applications.
  • the coating compositions may in particular be used in pigmented form for the production of a primer surfacer layer or in pigment-free form for the production of an outer clear top coat layer or a transparent sealing layer of a multilayer coating. They may, for example, be used for the production of a clear top coat layer on a previously applied color-imparting and/or special effect-imparting predried base coat layer.
  • the coating compositions may be applied by means of conventional application methods, in particular, by spraying onto any desired uncoated or precoated substrates, for example, of metal or plastics.
  • the coating compositions according to the invention may exhibit low application viscosities at a comparatively high resin solids content. This is advantageous in the case of spray application, because it is possible, for example, then to use conventional spray application units, as are used for the application of liquid coatings in industrial coating facilities.
  • layers of the coating compositions according to the invention may initially be flashed off to remove solvent, for example, for one to five minutes at 20 to 80 0 C.
  • Thermal curing then proceeds at object temperatures above the melting temperature of the isocyanate-functional polyurethane resin(s) A contained in the corresponding coating composition, for example, for 5 to 30 minutes at 40 to 22O 0 C 1 for example, by baking. If the difference between the melting temperature and the actual curing temperature is sufficiently large, it is possible initially to effect only or substantially only the melting of the polyurethane resin A particles, before the actual crosslinking subsequently proceeds during and/or after a further increase in temperature to the curing temperature. During and/or after melting the polyurethane resin A particles the polyurethane resin A may become incorporated into the resin matrix.
  • thermal curing is combined with curing by free- radical polymerization of oleftnic double bonds induced by irradiation with high-energy radiation, in particular UV radiation.
  • Thermal curing and radiation curing may here proceed simultaneously or in any desired order. Melting of the polyurethane resin A particles must, however, be ensured prior to curing.
  • Polyurethane diisocyanates were produced by reacting HDI (1 ,6- hexane diisocyanate) with one or more diols in accordance with the following general synthesis method:
  • HDI was initially introduced into a 2 litre four-necked flask equipped with a stirrer, thermometer and column and 0.01 wt.% dibutyltin dilaurate, based on the quantity of isocyanate introduced, were added.
  • the content of the flask was heated to 60 0 C.
  • the diol (mixture) was then apportioned and a temperature was maintained so that the hot reaction mixture did not solidify.
  • the reaction mixture was stirred until the theoretical free isocyanate content was reached.
  • the hot melt was then discharged and allowed to cool and solidify.
  • the melting behavior of the resultant polyurethane diisocyanates was investigated by means of DSC (differential scanning calorimetry, heating rate 10 K/min). Examples 1a to 1f are shown in Table 1. The Table states which reactants were reacted together in what molar ratios and the final temperature of the melting process measured by DSC is stated in 0 C.
  • Polyurethane polyisocyanates were produced by reacting t-HDI (trimeric hexanediisocyanate, Desmodur® N3600 from Bayer), HDI and a diol component in accordance with the following general synthesis method:
  • a mixture of a t-HDI and HDI was initially introduced into a 2 litre four-necked flask equipped with a stirrer, thermometer and column and 0.1 % by weight dibutyl tin dilaurate, based on the quantity of isocyanate introduced, were added.
  • the reaction mixture was heated to 60 0 C.
  • a diol (mixture) was then apportioned and a temperature was maintained so that the hot reaction mixture did not solidify.
  • the reaction mixture was stirred until the theoretical free isocyanate content was reached.
  • the hot melt was then discharged and allowed to cool and solidify.
  • the melting behavior of the resultant polyurethane polyisocyanates was investigated by means of DSC (differential scanning calorimetry, heating rate 10 K/min).
  • Examples 2a to 2d are shown in Table 2.
  • the Table states which reactants were reacted together in what molar ratios and the final temperature of the melting process measured by DSC is stated in 0 C.
  • Example 3 (Production of a Clear Coat Composition and an Outer Clear Coat Layer of a Multi-Layer Coating for Comparison Purposes):
  • a base was prepared by mixing the following components: 61.6 pbw (parts by weight) of a 65 wt-% solution of a methacrylic copolymer (acid value 5 mg KOH/g, hydroxyl value 147 mg KOH/g) in a 2 : 1 mixture of Solvesso® 100 and butyl acetate
  • a clear coat was prepared by mixing 100 pbw of the base with 50 pbw of a 68 wt-% solution of a polyisocyanate hardener mixture (isocyanurate of isophorone diisocyanate and isocyanurate of hexamethylene diisocyanate in a weight ratio of 2 : 1 ) in a 2 : 1 mixture of Solvesso® 100 and butyl acetate.
  • the initial flow time according to DIN EN ISO 2431 with a DIN 4 cup at 20°C was determined directly after mixing the base and the polyisocyanate hardener (28 seconds).
  • the pot-life of the clear coat in terms of the time period for doubling the initial flow time was two hours.
  • a metal panel provided with a cataphoretic primer and a 35 ⁇ m thick hydroprimer surfacer layer applied thereto and baked was spray- coated with a black waterborne base coat in a dry layer thickness of 15 ⁇ m, flashed off for 5 minutes at 70 0 C and then spray-coated with the clear coat in a vertical position in a wedge shape with a layer thickness gradient from 10 ⁇ m to 70 ⁇ m dry layer thickness, and after 10 minutes flashing off at room temperature, baking was carried out for 30 minutes at 130 0 C (object temperature). The clear coat sag limit was visually determined. Examples 4a to 4k (Production of Clear Coat Compositions and Outer Clear Coat Layers of Multi-Layer Coatings According to the Invention):
  • Solid polyurethane diisocyanates of Examples 1a to 1e and solid polyurethane polyisocyanates of Examples 2a to 2d were in each case comminuted, ground and sieved by means of grinding and sieving methods conventional for the production of powder coatings and, in this manner, converted into binder powders with an average particle size of 50 ⁇ m (determined by means of laser diffraction).
  • Example 3 was repeated several times wherein the solution of the polyisocyanate hardener mixture was replaced by a pulverulent polyurethane diisocyanate or polyurethane polyisocyanate prepared according to the procedure described in the preceding paragraph.
  • the replacement was performed by substituting the pulverulent polyurethane diisocyanate or polyisocyanate for the solution of the polyisocyanate hardener mixture in each case according to a 100 mol-% substitution of NCO.
  • the initial flow time was adjusted to the same value as in Example 3 by adding an appropriate amount of a 2 : 1 mixture of Solvesso® 100 and butyl acetate.
  • Table 3 shows the pot-life and the measured sag limit in ⁇ m, with reference to Examples 3 and 4a to 4k.

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  • Chemical & Material Sciences (AREA)
  • Organic Chemistry (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Health & Medical Sciences (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Dispersion Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Materials Engineering (AREA)
  • Wood Science & Technology (AREA)
  • Polyurethanes Or Polyureas (AREA)
  • Paints Or Removers (AREA)

Abstract

Cette invention concerne des compositions d'enrobage liquides non aqueuses contenant au moins une résine de polyuréthanne à fonction isocyanate (A) en tant qu'unique composant polyisocyanate, et au moins un liant (B) qui comprend des groupes réagissant aux groupes isocyanates de (A). La résine (A) se présente sous la forme de particules dont la température de fusion est comprise entre 40 et 180 °C.
PCT/US2007/000356 2006-01-09 2007-01-09 Compositions d'enrobage liquides non aqueuses WO2007081844A2 (fr)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8691006B2 (en) 2005-09-21 2014-04-08 Axalta Coating Systems Ip Co., Llc Non-aqueous, liquid coating compositions

Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4442280A (en) * 1981-08-12 1984-04-10 Bayer Aktiengesellschaft Heterogeneous systems of polyol/diphenyl methane uret dione diisocyanates and a process for their production
US5338819A (en) * 1991-11-29 1994-08-16 Basf Corporation Solid isocyanate derivatives useful in one component polyurethane adhesives
EP1514885A1 (fr) * 2003-09-12 2005-03-16 Bayer MaterialScience LLC Revêtement composite geotextile/polyuréthanne à base des composés de polyuréthanne monocomposant, liquide et héterogène

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4442280A (en) * 1981-08-12 1984-04-10 Bayer Aktiengesellschaft Heterogeneous systems of polyol/diphenyl methane uret dione diisocyanates and a process for their production
US5338819A (en) * 1991-11-29 1994-08-16 Basf Corporation Solid isocyanate derivatives useful in one component polyurethane adhesives
EP1514885A1 (fr) * 2003-09-12 2005-03-16 Bayer MaterialScience LLC Revêtement composite geotextile/polyuréthanne à base des composés de polyuréthanne monocomposant, liquide et héterogène

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US8691006B2 (en) 2005-09-21 2014-04-08 Axalta Coating Systems Ip Co., Llc Non-aqueous, liquid coating compositions

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