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
  • C08G18/0804—Manufacture of polymers containing ionic or ionogenic groups
  • C08G18/0819—Manufacture of polymers containing ionic or ionogenic groups containing anionic or anionogenic groups
  • C08G18/0828—Manufacture of polymers containing ionic or ionogenic groups containing anionic or anionogenic groups containing sulfonate groups or groups forming them
• • 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
  • C08G18/10—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
• • 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
  • C08G18/10—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step
  • C08G18/12—Prepolymer processes involving reaction of isocyanates or isothiocyanates with compounds having active hydrogen in a first reaction step using two or more compounds having active hydrogen in the first polymerisation step
• • 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
  • C08G18/30—Low-molecular-weight compounds
  • C08G18/32—Polyhydroxy compounds; Polyamines; Hydroxyamines
  • C08G18/3225—Polyamines
  • C08G18/3228—Polyamines acyclic
• • 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
  • C08G18/42—Polycondensates having carboxylic or carbonic ester groups in the main chain
  • C08G18/4205—Polycondensates having carboxylic or carbonic ester groups in the main chain containing cyclic groups
  • C08G18/4208—Polycondensates having carboxylic or carbonic ester groups in the main chain containing cyclic groups containing aromatic 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
  • C08G18/70—Polymeric products of isocyanates or isothiocyanates with compounds having active hydrogen characterised by the isocyanates or isothiocyanates used
  • C08G18/72—Polyisocyanates or polyisothiocyanates
• • 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
  • C08G18/73—Polyisocyanates or polyisothiocyanates acyclic
• • 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
  • C08G18/753—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 containing one isocyanate or isothiocyanate group linked to the cycloaliphatic ring by means of an aliphatic group having a primary carbon atom next to the isocyanate or isothiocyanate group
  • C08G18/755—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 containing one isocyanate or isothiocyanate group linked to the cycloaliphatic ring by means of an aliphatic group having a primary carbon atom next to the isocyanate or isothiocyanate group and at least one isocyanate or isothiocyanate group linked to a secondary carbon atom of the cycloaliphatic ring, e.g. isophorone diisocyanate
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J7/00—Chemical treatment or coating of shaped articles made of macromolecular substances
  • C08J7/04—Coating
• • 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
  • C09D175/06—Polyurethanes from polyesters
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08J—WORKING-UP; GENERAL PROCESSES OF COMPOUNDING; AFTER-TREATMENT NOT COVERED BY SUBCLASSES C08B, C08C, C08F, C08G or C08H
  • C08J2475/00—Characterised by the use of polyureas or polyurethanes; Derivatives of such polymers
  • C08J2475/04—Polyurethanes
  • C08J2475/06—Polyurethanes from polyesters

Definitions

• the invention relates to new aqueous polyester-polyurethane dispersions, to coating compositions comprising these dispersions and to the coating materials prepared therefrom.
• Ionically modified polyurethane dispersions and their aqueous formulations are known prior art.
• One important field of use of aqueous formulations of ionically modified polyurethanes lies in the area of the coating of plastics components.
• This tactility can be described using terms such as velvety, soft, rubber-like or warm, whereas, for example, the surface of a painted car body or else an unpainted polymer sheet or one coated with a customary clearcoat or topcoat material and made, for example, of ABS, Makrolon® (polycarbonate, Bayer AG) or plexiglass feels cold and smooth.
• aqueous soft feel coating materials based on the polyurethane chemistry, as disclosed, by way of example, in DE-A1 44 06 159. As well as an excellent soft feel effect, these coating materials also produce coatings having good resistance and protective effect for the plastics substrate.
• a coating system of this kind is composed of primer, optionally a basecoat and a topcoat.
• the primer in this system takes on the function of the adhesion promoter between substrate and coating material.
• DE-A1 2 651 506 discloses a process for preparing water-dispersible polyurethanes.
• the products of this process are unsuitable for use as a single-coat soft feel coating material for plastics components, since they lack the necessary adhesion properties.
• DE-A1 101 38 765 discloses that the use of polyethers prepared starting from aromatic diols in aqueous polyurethane (PU) dispersions leads to products which in view of their improved adhesion to a variety of substrates are suitable as priming binders. Because of their inadequate tactility, however, the products are not suitable for use as soft feel coating materials.
• PU polyurethane
• An object of the present invention was to provide aqueous polyurethane dispersions which have suitability as soft feel coating materials and at the same time have excellent adhesion to plastics substrates.
• the present invention is directed to a process for preparing polyester-polyurethane resin dispersions.
• the process includes:
• the present invention further provides polyester-polyurethane resin dispersions obtained according to the above-described process.
• the present invention also provides coating compositions that include 15 to 45 parts by weight of the above-described aqueous polyester-polyurethane resin dispersion, 15 to 45 parts by weight of a hydroxy-functional, aqueous or water-dilutable binder, 0 to 60 parts by weight of an inorganic filler and/or matting agent, 1 to 60 parts by weight of a polyisocyanate, 0.1 to 30 parts by weight of pigments and 1 to 15 parts by weight of customary coatings auxiliaries, the sum of the components making 100.
• the present invention additionally provides a coating system that includes a substrate and one or more coating films, where at least one of the coating films includes the above-described polyester-polyurethane resin dispersion.
• polyurethane dispersions comprising polyester polyols, including a fraction of more than 60% by weight of polyester polyols based on aromatic dicarboxylic acids, substantially enhance the adhesion properties of the coatings producible therewith on plastics substrates.
• the present invention provides a process for preparing polyester-polyurethane resin dispersions, characterized in that one or more polyol components i) having an average molecular weight of at least 300 daltons, at least one of the components being a polyester polyol and the fraction of polyester polyol based on aromatic polycarboxylic acids being more than 60% by weight, optionally one or more polyol components having an average molecular weight of 62 to 299 daltons, optionally a compound which is monofunctional for the purposes of the isocyanate polyaddition reaction and has an ethylene oxide content of at least 50% by weight and a molecular weight of at least 400 daltons are reacted with a polyisocyanate to form a prepolymer, which is dissolved in an organic solvent and reacted with one or more aliphatic polyamines having a molecular weight of 60 to 300 daltons or hydrazine and a hydrophilicized aliphatic diamine, the dispersion is subsequently precipitated by adding
• polyester-polyurethane resin dispersions obtainable in accordance with the process of the invention.
• Polyurethane also embraces “polyurethane-polyureas”, i.e. high molecular weight compounds containing not only urethane groups but also urea groups.
• Synthesis components i) suitable for the aqueous polyester-polyurethane resin dispersions of the invention are organic compounds containing at least two free hydroxyl groups capable of reaction with isocyanate groups.
• Examples of compounds of this kind are relatively high molecular weight compounds from the classes of the polyester, polyester amide, polycarbonate, polyacetal and polyether polyols having molecular weights of at least 300, preferably 500 to 8000, more preferably 800 to 5000.
• Preferred compounds are for example those containing two hydroxyl groups (difunctional), such as polyester diols or polycarbonate diols.
• polyester polyols i) are linear polyester diols or else polyester polyols with low degrees of branching, such as are preparable conventionally from aliphatic, cycloaliphatic and aromatic dicarboxylic or polycarboxylic acids and/or their anhydrides, such as succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic, nonanedicarboxylic, decanedicarboxylic, terephthalic, isophthalic, o-phthalic, tetrahydrophthalic, hexahydrophthalic or trimellitic acid and also acid anhydrides, such as o-phthalic, trimellitic or succinic anhydride, or a mixture thereof, and polyhydric alcohols, such as ethanediol, di-, tri- and tetraethylene glycol, 1,2-propanediol, di-, tri- and tetrapropylene glycol, 1,
• suitable polyol components include homopolymers or copolymers of lactones, which are obtained preferably by subjecting lactones or lactone mixtures, such as butyrolactone, ⁇ -caprolactone and/or methyl- ⁇ -caprolactone, to addition reactions with suitable starter molecules having a functionality of two and/or more, such as, for example, the low molecular weight polyhydric alcohols specified above as synthesis components for polyester polyols.
• Hydroxyl-containing polycarbonates as well are suitable polyol components i); for example, those preparable by reacting diols such as 1,4-butanediol and/or 1,6-hexanediol with diaryl carbonates, such as diphenyl carbonate, dialkyl carbonate, such as dimethyl carbonate, or phosgene, and having a molecular weight of 800 to 5000.
• diols such as 1,4-butanediol and/or 1,6-hexanediol
• diaryl carbonates such as diphenyl carbonate, dialkyl carbonate, such as dimethyl carbonate, or phosgene, and having a molecular weight of 800 to 5000.
• polyester polyols based on dicarboxylic acids or their anhydrides such as o-phthalic, isophthalic and terephthalic acid and glycols such as 1,4-butanediol, 1,6-hexanediol and/or 2,2-dimethyl-1,3-propanediol (neopentyl glycol).
• aromatic dicarboxylic acids or their anhydrides in a mixture with polyester diols based on adipic acid and glycols such as 1,4-butanediol, 1,6-hexanediol and/or 2,2-dimethyl-1,3-propanediol (neopentyl glycol).
• polyester diols based on adipic acid and glycols such as 1,4-butanediol, 1,6-hexanediol and/or 2,2-dimethyl-1,3-propanediol (neopentyl glycol).
• copolymers of 1,6-hexanediol with ⁇ -caprolactone and diphenyl carbonate or dimethyl carbonate having a molecular weight of 1000 to 4000
• polycarbonate diols having a molecular weight of from 1000 to 3000.
• polyether polyols examples being the polyadducts of styrene oxides, ethylene oxide, propylene oxide, tetrahydrofuran, butylene oxide and epichlorohydrin, and also their mixed adducts and grafting products, and also the polyether polyols obtained by condensing polyhydric alcohols or mixtures thereof and the polyether polyols obtained by alkoxylating polyhydric alcohols, amines and amino alcohols.
• the fraction of aromatic carboxylic acid groups, relative to all of the carboxylic acid groups used to prepare the polyester component, in the polyol component i) is at least 60 mol %, preferably at least 70 mol % and more preferably at least 80 mol %. Based on the polyol component i) the fraction of polyester polyol based on aromatic polycarboxylic acids ought preferably to be more than 60% by weight.
• Suitable synthesis components ii) are diols of the molecular weight range 62 to 299. Suitable such compounds include for example the polyhydric alcohols, especially dihydric alcohols, stated for preparing the synthesis components i), and also, furthermore, low molecular weight polyester diols, such as, for example, bis(hydroxyethyl) adipate or short-chain homoadducts and mixed adducts of ethylene oxide or of propylene oxide, prepared starting from aromatic diols.
• Preferred synthesis components ii) are 1,2-ethanediol, 1,4-butanediol, 1,6-hexanediol and 2,2-dimethylpropane-1,3-diol. Particular preference is given to 1,4-butanediol and 1,6-hexanediol.
• polyester-polyurethane resin dispersions of the invention contain, based on solids, from 0% to 4% by weight of ethylene oxide units which are incorporated terminally and/or laterally and which, through the use of the synthesis components iii) in the course of the isocyanate polyaddition operation, can be incorporated in a simple way.
• Hydrophilic synthesis components iii) for incorporating terminal hydrophilic chains containing ethylene oxide units are compounds of the formula (I) H—Y′—X—Y—R (I) in which
• monofunctional synthesis components iii) are used only in molar amounts of ⁇ 10 mol %, based on the polyisocyanate used, so as to ensure the desired high molecular weight construction of the polyurethane elastomers.
• monofunctional alkylene oxide polyethers where larger molar amounts of monofunctional alkylene oxide polyethers are used it is advantageous to use, as well, trifunctional compounds containing isocyanate-reactive hydrogen atoms, though with the proviso that the average of the functionality of the starting compounds i) to iii) is not greater than 2.7, preferably not greater than 2.3.
• the monofunctional, hydrophilic synthesis components are prepared in analogy to the manner described in DE-A 2 314 512 or DE-A 2 314 513 or in U.S. Pat. No. 3,905,929 or U.S. Pat. No. 3,920,598, by alkoxylating a monofunctional starter such as n-butanol or N-methylbutylamine, for example, using ethylene oxide and optionally a further alkylene oxide such as propylene oxide, for example.
• Preferred synthesis components iii) are the copolymers of ethylene oxide with propylene oxide, with an ethylene oxide mass fraction of more than 50%, more preferably from 55 to 89%.
• One preferred embodiment uses as synthesis components iii) compounds having a molecular weight of at least 400 daltons, preferably at least 500 daltons and more preferably of 1200 to 4500 daltons.
• Compounds suitable as synthesis components iv) are any desired organic compounds containing at least two free isocyanate groups per molecule, such as diisocyanates X(NCO) 2 , where X is a divalent aliphatic hydrocarbon radical having 4 to 12 carbon atoms, a divalent cycloaliphatic hydrocarbon radical having 6 to 15 carbon atoms, a divalent aromatic hydrocarbon radical having 6 to 15 carbon atoms or a divalent araliphatic hydrocarbon radical having 7 to 15 carbon atoms.
• X is a divalent aliphatic hydrocarbon radical having 4 to 12 carbon atoms
• a divalent cycloaliphatic hydrocarbon radical having 6 to 15 carbon atoms a divalent aromatic hydrocarbon radical having 6 to 15 carbon atoms or a divalent araliphatic hydrocarbon radical having 7 to 15 carbon atoms.
• X is a divalent aliphatic hydrocarbon radical having 4 to 12 carbon atoms
• diisocyanates examples include tetramethylene diisocyanate, methylpentamethylene diisocyanate, hexamethylene 1,6-diisocyanate, dodecamethylene diisocyanate, 1,4-diisocyanatocyclohexane, 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethycyclohexane, 4,4′-diisocyanatodicyclohexylmethane, 2,2-bis(4-isocyanatocyclohexyl)propane, 1,4,-diisocyanatobenzene, 2,4-diisocyanatotoluene, 2,6-diisocyanatotoluene, 4,4′-diisocyanatodiphenylmethane, 2,2′- and 2,4′-diisocyanatodiphenylmethane, p-xylylene diisocyanate, 1,
• Suitable synthesis components v) include aliphatic and/or alicyclic primary and/or secondary polyamines, preference being given for example to 1,2-ethanediamine, 1,6-hexamethylenediamine, 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane (isophoronediamine), piperazine 1,4-diaminocyclohexane, bis(4 aminocyclohexyl)methane, adipic dihydrazide or diethylenetriamine and also to hydrazine or hydrazine hydrate.
• polyether polyamines which come about formally by replacement of the hydroxyl groups of the above-described polyether polyols by amino groups.
• Polyether polyamines of this kind can be prepared by reacting the corresponding polyether polyols with ammonia and/or primary amines.
• Particularly preferred synthesis components v) are 1-amino-3,3,5-trimethyl-5-aminomethylcyclohexane (isophoronediamine), 1,2-ethanediamine, piperazine and diethylenetriamine.
• the polyester-polyurethane resin dispersions of the invention contain, based on solids, from 1.5 to 30, preferably from 3 to 13.5 mmol of alkali metal salts of sulphonic acids/100 g of polyurethane resin.
• the incorporation of ionic groups of this kind is accomplished conventionally by using synthesis components vi), such as diamines or polyamines containing alkali metal sulphonate groups, for example, when synthesizing the polyurethane resins of the invention.
• suitable compounds vi) are the alkali metal salts of N-(2-aminoethyl)-2-aminoethanesulphonic acid. The sodium salt is preferred.
• component i Normally 20 to 94.5 parts, preferably 30 to 80 parts and more preferably 50 to 76.5 parts by weight of component i), 0 to 30%, preferably 0 to 15% by weight of component ii), 0 to 10 parts, preferably 0.5 to 6 parts by weight of component iii), 4.5 to 50 parts, preferably 5 to 30 parts and more preferably 7.5 to 20 parts by weight of component iv), 0.5 to 13 parts, preferably 1 to 5 parts by weight of component v) and 0.5 to 8 parts, preferably 1.5 to 5.5 parts by weight of component vi) are used, with the proviso that the sum of the components makes 100% by weight.
• the polyurethane resin dispersions of the invention are prepared by the acetone method (D. Dieterich in Houben-Weyl: Methoden der Organischen Chemie, Volume E20, pp. 1670-81 (1987)).
• a prepolymer containing isocyanate groups is synthesized from the synthesis components i) to iv).
• the amounts of the individual components used are such as to give an isocyanate index of 1.1 to 3.5, preferably 1.3 to 2.
• the isocyanate content of the prepolymers is between 1.5% and 7.5%, preferably between 2% and 4.5% and more preferably between 2.5% and 3.5%. It should also be ensured when selecting the amount of synthesis components i) to iv) that the arithmetic, number-average functionality is situated between 1.80 and 3.50, preferably between 1.95 and 2.25.
• the prepolymer prepared in stage 1 is dissolved in an organic solvent at least partly miscible with water and carrying no isocyanate-reactive groups.
• a preferred solvent is acetone. It is also possible, though, to use other solvents, such as 2-butanone, tetrahydrofuran or dioxane or mixtures of these solvents.
• the amounts of solvent to be used are to be such that the resulting solids content is from 20% to 80%, preferably from 30% to 50%, more preferably from 35% to 45% by weight.
• the isocyanate-containing prepolymer solution is reacted with mixtures of the amino-functional synthesis components v) to vi), with chain extension, to form the high molecular weight polyurethane resin.
• the amounts of the synthesis components are such that for each mole of isocyanate groups in the dissolved prepolymer there are 0.3 to 0.93 mol, preferably 0.5 to 0.85 mol, of primary and/or secondary amino groups in synthesis components v) to vi).
• the arithmetic, number-average isocyanate functionality of the resulting polyester-polyurethane resin of the invention is between 1.55 and 3.10, preferably between 1.90 and 2.35.
• the arithmetic, number-average molecular weight (Mn) is between 4500 and 250 000, preferably between 10 000 and 80 000 daltons.
• the high molecular weight polyurethane resin is precipitated, by adding water to the solution, in the form of a fine dispersion.
• free sulphonic acid groups are optionally neutralized between the third and fourth steps.
• aqueous polyester-polyurethane resin dispersions of the invention have a solids content of 30% to 65%, preferably from 35% to 55% by weight.
• the coating compositions comprising the polyester-polyurethane resin dispersions of the invention can be used as aqueous soft feel coating materials, being distinguished by outstanding adhesion not only to various substrate surfaces, preferentially plastics substrates, but also to subsequent coating films, by improved condensation resistance and solvent resistance of the coating system as a whole, and by their extremely low VOC.
• the present invention therefore likewise provides coating compositions comprising
• the coating compositions of the invention contain 15 to 45 parts, preferably 25 to 37.5 parts, more preferably 30 to 35 parts by weight of A), 15 to 45 parts, preferably 25 to 37.5 parts, more preferably 30 to 35 parts by weight of B), 0 to 60 parts, preferably 4 to 45 parts, more preferably 7.5 to 30 parts by weight of C), 1 to 60 parts, preferably 2.5 to 30 parts, more preferably 4 to 20 parts by weight of D), 0.1 to 15 parts, preferably 5 to 25 parts, more preferably 10 to 20 parts by weight of E) and 1 to 15 parts, preferably 1.5 to 10 parts, more preferably 2 to 6 parts by weight of F).
• Suitable coating-composition components B) are hydroxy-functional polymers from the classes of the polyesters, polyurethanes and polyacrylates and/or copolymers or graft polymers of the stated polymer types, as described for example in EP-A 0 542 105.
• Particularly preferred formulations are aqueous or water-thinnable formulations of hydroxy-functional polyurethanes or polyacrylates or graft polymers of acrylates on polyurethanes.
• Particular preference is given to aqueous or water-thinnable formulations of hydroxy-functional polyurethanes of the polyester polyurethane type.
• polyisocyanates containing free NCO groups are for example those based on isophorone diisocyanate, hexamethylene diisocyanate, 1,4-diisocyanatocyclohexane, bis(4-isocyanatocyclohexane)methane or 1,3-diisocyanatobenzene or based on paint polyisocyanates such as polyisocyanates containing allophanate, uretdione, biuret or isocyanurate groups and derived from 1,6-diisocyanatohexane, isophorone diisocyanate or bis(4-isocyanatocyclohexane)methane, or paint polyisocyanates containing urethane groups and based on 2,4- and/or 2,6-diisocyanatotoluene or isophorone diisocyanate on the one hand and on low molecular
• Preferred coating-composition components D) are low-viscosity, hydrophobic or hydrophilicized polyisocyanates containing free isocyanate groups and based on aliphatic, cycloaliphatic, araliphatic and/or aromatic isocyanates, particular preference being given to aliphatic or cycloaliphatic isocyanates.
• These polyisocyanates have at 23° C. in general a viscosity of 10 to 3500 mPas. If necessary the polyisocyanates can be employed as a blend with small amounts of inert solvents, in order to lower the viscosity to a figure within the stated range.
• Triisocyanatononane can also be used, alone or in mixtures, as a crosslinker component.
• Water-soluble and/or dispersible polyisocyanates are obtainable for example by modification with carboxylate, sulphonate and/or polyethylene oxide groups and/or polyethylene oxide/polypropylene oxide groups.
• Hydrophilicization of the polyisocyanates is possible for example by reaction with deficit amounts of monohydric hydrophilic polyether alcohols.
• the preparation of hydrophilicized polyisocyanates of this kind is described for example in EP-A 0 540 985.
• Also highly suitable are the polyisocyanates containing allophanate groups that are described in EP-A 0 959 087, which are prepared by reacting polyisocyanates of low monomer content with polyethylene oxide polyether alcohols under allophanatisation conditions.
• water-dispersible polyisocyanate mixtures described in DE-A 10 007 821 based on triisocyanatononane, and also polyisocyanates hydrophilicized with ionic groups (sulphonate groups, phosphonate groups), as described for example in DE-A 10 024 624. Hydrophilicization through addition of commercially customary emulsifiers is also a possibility.
• hydrophilically modified polyisocyanates as a coating-composition component D) is preferred. Particular preference is given to polyisocyanates modified with sulphonate groups, as described for example in DE-A 10 024 624 p. 3 line 22 to p. 5 line 34 and p. 6 line 40 to p. 7 line 50 and p. 9 line 38 to line 50. In principle it is of course also possible to use mixtures of different crosslinker resins.
• polyester-polyurethane resin dispersions of the invention can be used for coating substrates.
• Further suitable substrates are wood, metal, leather or textiles.
• plastics substrates coated with coating compositions comprising the polyester-polyurethane dispersions of the invention.
• the invention additionally provides a coating system comprising a substrate, one or more coating films, characterized in that at least one of the coating films comprises the polyester-polyurethane resin dispersions of the invention. Preference is given to a single-coat system.
• Viscosity measurements were conducted using a cone-plate viscometer Pysica Viscolab LC3 ISO from Physica, Stuttgart, Germany in accordance with DIN 53019, with a shear rate of 40 ⁇ l.
• the mean particle size was determined by laser correlation spectroscopy (Zetasizer® 1000, Malvern Instruments,dorfberg, Germany).
• a 5 l reaction vessel with stirrer, heating jacket, thermometer, distillation column and nitrogen inlet is charged with the acid components, which are melted at 160° C. under a nitrogen flow of 10-12 l/h. Subsequently the stirrer is switched on, the diol components are added and the nitrogen flow is reduced to 7-8 l/h.
• the reaction mixture is slowly heated to 200° C. The heating rate is regulated so that the overhead column temperature does not exceed 105° C.
• the reaction mixture is held at 200° C. until the overhead column temperature falls below 90° C. Then the column is removed and the nitrogen stream is slowly increased to 30-32 l/h.
• Coating-composition component Bayhydrol ® XP 2429 aqueous, hydroxy-functional polyester polyurethane dispersion (Bayer AG, Leverkusen, DE) Solids content: 55% by weight in water/NMP Hydroxyl content: 0.8% by weight
• polyester (A) 1632 parts of polyester (A) are dewatered at 100° C. under a reduced pressure of approximately 14 torr and, following addition of 85 parts of a polyether monoalcohol formed from n-butanol, ethylene oxide and propylene oxide (in a molar ratio of 83:17) with an OH number of 30, a mixture of 244.2 parts of 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, Desmodur® I, Bayer AG Leverkusen) and 185 parts of hexane 1,6-diisocyanate (Desmodur® H, Bayer AG Leverkusen) is added.
• a polyether monoalcohol formed from n-butanol, ethylene oxide and propylene oxide in a molar ratio of 83:17
• a bluish white dispersion of the solid is formed in a mixture of water and acetone. Removal of the acetone by distillation leaves an aqueous dispersion having a solids content of 40 ⁇ 1% by weight. Measurement of the particle diameter by laser correlation gives a figure of approximately 230 nm.
• the solids of the dispersion contains 2.9% of polyethylene oxide segments and 3.1 mmol of sulphonate groups (—SO 3 ⁇ ) per 100 g of solids.
• the fraction of aromatic carboxylic acid groups relative to all of the carboxylic acid groups of synthesis component i) is 0% by weight.
• the solids content is adjusted by adding water to 45 ⁇ 1% by weight. Measurement of the particle diameter by laser correlation gave a figure of approximately 94 nm.
• the solids of the dispersion contains 10.3 mmol of sulphonate groups (—SO 3 ⁇ ) per 100 g of solids.
• the fraction of aromatic carboxylic acid groups, relative to all of the carboxylic acid groups of synthesis component i) is 26.5 mol %.
• the solids content is adjusted by adding water to 40 ⁇ 1% by weight.
• the solids of the dispersion contains 10.3 mmol of sulphonate groups (—SO 3 ⁇ ) per 100 g of solids.
• the fraction of aromatic carboxylic acid groups, relative to all of the carboxylic acid groups of synthesis component i) is 51.9 mol %.
• a mixture of 425 parts of polyester (A) and 1500 parts of polyester (B) is dewatered at 110° C. under reduced pressure of about 14 torr and then at 70° C. 300.7 parts of hexane 1,6-diisocyanate (Desmodur® H, Bayer AG Leverkusen) are added. The mixture is stirred at 100° C. until it has an isocyanate content of 2.74% (theoretical 2.98%). After cooling has taken place to 50-60° C. 3955 parts of anhydrous acetone are added.
• the solids content is adjusted by adding water to 40 ⁇ 1% by weight.
• the solids of the dispersion contains 9.9 mmol of sulphonate groups (—SO 3 ⁇ ) per 100 g of solids.
• the fraction of aromatic carboxylic acids as a proportion of the synthesis component i) is 76.4 mol %.
• the solids content is adjusted by adding water to 40 ⁇ 1% by weight.
• the solids of the dispersion contains 10.5 mmol of sulphonate groups (—SO 3 ⁇ ) per 100 g of solids.
• the fraction of aromatic carboxylic acid groups relative to all of the carboxylic acid groups of synthesis component i) is 100 mol %.
• polyester (C) 1955 parts are dewatered at 100° C. under a reduced pressure of approximately 14 torr and, following addition of 92.5 parts of a polyether monoalcohol formed from n-butanol, ethylene oxide and propylene oxide (in a molar ratio of 83:19) with an OH number of 30, a mixture of 254.2 parts of 1-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate, Desmodur® I, Bayer AG, Leverkusen) and 192.7 parts of hexane 1,6-diisocyanate (Desmodur® H, Bayer AG Leverkusen) is added.
• a polyether monoalcohol formed from n-butanol, ethylene oxide and propylene oxide in a molar ratio of 83:19
• the solids content was adjusted by adding water to 40 ⁇ 1% by weight.
• the solids of the dispersion contains 2.75% of polyethylene oxide segments and 2.9 mmol of sulphonate groups (—SO 3 ⁇ ) per 100 g of solids.
• the fraction of aromatic polycarboxylic acids as a proportion of synthesis component i) is 76.4 mol %.
• the solids content is adjusted by adding water to 40 ⁇ 1% by weight. Measurement of the particle diameter by laser correlation gives a figure of approximately 230 nm.
• the solids of the dispersion contains 12.8 mmol of sulphonate groups (—SO 3 ⁇ ) per 100 g of solids.
• the fraction of aromatic carboxylic acid groups relative to all of the carboxylic acid groups of synthesis component i) is 100 mol %.
• Example 2 110 Example 3 110
• Example 4 110 Example 5 110
• Example 6 110 Bayhydrol ® XP 2429 1) 100 100 100 100 100 100 100 100 Water 90 90 90 90 90 90 90 Byk ® 348 2) 0.8 0.8 0.8 0.8 0.8 Defoamer DNE 3) Tegowet ® KL245 4) 1.1 1.1 1.1 1.1 1.1 (50% in water) Aquacer ® 535 2) 5.6 5.6 5.6 5.6 5.6 Sillitin ® Z86 5) 12.7 12.7 12.7 12.7 12.7 Pergopak ® M3 6) 19.1 19.1 19.1 19.1 19.1 Talc IT extra 7) 6.4 6.4 6.4 6.4 6.4 6.4 Bayferrox ® 318M 1) 50.8 50.8 50.8 50.8 50.8 Matting agent OK412 8) 6.4 6.4 6.4 6.4 6.4 6.4 6.4 Bayferrox ® 318M 1) 50.8 50.8 50.8 50.8 50.8 Matting agent OK412
• the single-coat topcoat formulations of table 1 are applied by spraying (3-5 bar, nozzle size 1.4, dry film thickness about 30 ⁇ m) to plastics sheets measuring 148 ⁇ 102 ⁇ 3 mm. Prior to spray application the coating materials are adjusted to spray viscosity (25-30 s in ISO 5). The specimens are dried at room temperature for 10 minutes and at 80° C. for 30 minutes. The adhesion is assessed by means of cross-cut. The evaluation was made visually in stages from 0 to 5, with 0 denoting no detachment and 5 complete detachment (DIN 53 151 with adhesive tape removal).
• inventive examples have significantly better adhesion to the problem substrates tested than the coatings according to the prior art.

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
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• Engineering & Computer Science (AREA)
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