WO2018046334A1 - Coatings with radiation-curable hyperbranched polymers - Google Patents

Abstract

Provided are methods of making a hyperbranched star polymer, the method comprising: (a) obtaining a core comprising a polyol; (b) optionally extending the core with one or more chain extenders to form an extended intermediate; (c) reacting the core or the extended intermediate with a compound that comprises unsaturated free radical reaction sites to form the hyperbranched star polymer, the compound being selected from the group consisting of: an anhydride comprising one or more unsaturated groups, an epoxide comprising one or more unsaturated groups, and combinations thereof; wherein the hyperbranched star polymer is radiation-curable. Also provided are coatings comprising such hyperbranched star polymers.

Description

COATINGS WITH RADIATION-CURABLE HYPERBRANCHED POLYMERS

FIELD

[0001] The invention generally relates to hyperbranched polymers and their use in coating compositions. In particular, aspects of the invention are directed to radiation- curable hyperbranched polymers.

BACKGROUND

[0002] The solvents used in coatings and paints are a major source of man-made volatile organic compounds (VOC), which can have a negative impact on the environment. One approach to reducing the VOC of coatings is to utilize radiation-curable monomers or materials. These materials act as part of the carrier solvent for the other components of the coating formulation during application. After application onto the desired surface has been achieved, the coating is cured in situ by a free radical polymerization process typically initiated by a photoinitiator. Those radiation curable components are rendered no n- volatile in the process. H igh conversion and high crosslink density are generally desired. However, limited mobil ity of unsaturated sites on monomers hinders the development of high conversion rates and builds stress into the film as crosslinks are formed, resulting in brittle film characteristics.

[0003] Hyperbranched polymers with available unsaturation can improve conversion rates and increase the number of crosslinks formed as well as relieve some stress in the fi lm. However, standard hyperbranched polymers are somewhat limited with respect to the degree of flexibility they can bring to the cured film due to their radial architecture. There is thus a need for hyperbranched polymers that exhibit better flexibility, thereby imparting better film characteristics.

SUMMARY

[0004] One aspect of the invention pertains to a method of making a hyperbranched star polymer. In one or more embodiments, the method comprises:

(a) obtaining a core comprising a pol yol; (b) optionally extending the core with one or more chain extenders to form an extended intermediate;

(c) reacting the core or the extended intermediate with a compound that comprises unsaturated free radical reaction sites to form the hyperbranched star polymer, the compound being selected from the group consisting of: an anhydride comprising one or more unsaturated groups, an epoxide comprising one or more unsaturated groups, and combinations thereof;

wherein the hyperbranched star polymer is radiation-curable.

[0005] In some embodiments, either the compound comprises the anhydride comprising one or more unsaturated groups that is directly reacted with the core or the core is extended with a chain extender that comprises a saturated anhydride that is directly reacted with the core. In one or more embodiments, the polyol is selected from the group consisting of trimethylolpropane, pentaerythritol, a low molecular weight natural oil polyol, and combinations thereof. In some embodiments, the core further comprises a reaction product of the polyol and a di- or polyhydric acid. In one or more embodiments, the di-hydric acid comprises dimethylol propionic acid. In some embodiments, the compound comprises an unsaturated anhydride selected from the group consisting of nialcic anhydride, dimethyImaleic anhydride, dodeccnyl succi n ic anhydride, 2-octcn- ylsuccinic anhydride, oleic anhydride, erucic anhydride and combinations thereof.

[0006] In one or more embodiments, the method comprises:

(a) extending the core with a first chain extender that is a fully saturated anhydride to provide a first extended intermediate;

(b) reacting the first extended intermediate with

i. an unsaturated epoxide-functionai compound or

ii. a fully saturated epoxide-functionai compound to provide a second extended intermediate comprising reactive hydroxyI groups, and reacting the second extended intermediate comprising reactive hydroxyI groups with an unsaturated anhydride to form the hyperbranched star polymer.

[0007] In some embodiments, the saturated anhydride is selected from the group consisting of hexahydrophthalic anhydride, succinic anhydride, phthal ic anhydride, methylhexahydrophthalic anhydride and combinations thereof. In one or more embodiments, (b) comprises reacting the first extended intermediate with an unsaturated epoxide-functional compound. In some embodiments, the unsaturated epoxide- functional compound is selected from the group consisting of glycidyl methacrylatc, give idyl aery I ate, olcyl glycidyl ether and combinations thereof. In one or more embodiments, (b) comprises reacting the first extended intermediate with a fully saturated epoxide- f u n c t i o n a I compound to provide a second extended intermediate comprising reactive hydroxyl groups, and reacting the second extended intermediate comprising reactive hydroxyl groups with an unsaturated anhydride to form the hyperbranched star polymer. In some embodiments, the fully saturated epoxide-functional compound is selected from the group consisting of glycidyl neodecanoate. glycidyl ncononanoate and combinations thereof. In one or more embodiments, the unsaturated anhydride is selected from the group consisting of maleic anhydride, dimethylmaleic anhydride, dodecenylsuccinic anhydride, 2-octen- ylsuccinic anhydride, oleic anhydride, erucic anhydride and combinations thereof. In some embodiments, the method prov ides a hyperbranched star polymer containing a branch point w ith multiple chains.

[0008] Another aspect of the invention pertains to a method of producing a coating on a substrate surface, the method comprising:

(a) applying a coating composition comprising:

i. the hyperbranched star polymer made by the any of the methods described herein; and

ii. a photoinitiator

to a substrate surface;

(b) curing the polymer in situ by free radical polymerization.

[0009] In one or more embodiments, the curing comprises actinic radiation. In some embodiments, the photoinitiator is selected from the group consisting of diaryI ketone derivatives, benzoin alkyI ethers, aikoxy phenyl ketones, 0-acylated oximinoketones, polycyclic quinones, benzophenones and substituted benzophenones, xanthones, thioxanthones, chlorosulfonyl and chloromethyl polynuclear aromatic compounds. chlorosulfonyl and chloromethyl heterocyclic compounds, chlorosulfonyl and chloromethyl benzophenones and fluorenones, haloalkancs and combinations thereof.

[0010] Yet another aspect of the invention pertains to a coating produced by any of the methods described herein.

[001 1 ] An additional aspect of the invention pertains to a method of making a hyperbranched star polymer. In one or more embodiments, the method comprises

(a) reacting trimcthylolpropane with hexahydrophthalic anhydride to provide a first extended intermediate;

(b) reacting the first extended intermediate with glycidyl ncodecanoatc to provide a second extended intermediate; and

(c) reacting the second extended intermediate with dodeccnylsuccinic anhydride to form the hyperbranched star polymer.

FIGURES

[0012] FIG. 1 is a representation of a compound in accordance with one or more embodiments of the invention.

DETAILED DESCRIPTION

[0013] Before describing several exemplary embodiments of the invention, it is to be understood that the invention is not limited to the details of construction or process steps set forth in the following description. The invention is capable of other embodiments and of being practiced or being carried out in various ways.

[0014] It has been surprisingly found that selection of certain components for the preparation of hyperbranched polymers, hav ing multiple unsaturated sites, predominantly located at the extremities of the polymer, which are capable of free radical polymerization in a radiation cured system. Such polymers have relatively high crosslink density, which translates into improved water barrier properties and improved thermal stability as well.

[0015] The hyperbranched unsaturated "star" polymer of this invention may be advantageously formulated together with other radiation-curable components and essential elements of radiation-curable coatings, (such as photo initiators), then applied to a substrate in accord with methods typical for radiation-cured coatings and finally cured utilizing actinic radiation appropriate to activate whichever photoinitiator is being used. As used herein, "star" refers to a polymer having a single branch point with multiple chains or arms branching therefrom.

[0016] The hyperbranched polymers of one or more embodiments of the invention facilitate the incorporation of the performance advantages made possible by using hyperbranched polymers, (such as improved crossl ink density potential and reduced shrinkage), in radiation cured coating systems.

[0017] Accordingly, one aspect of the invention pertains to a method of making a hyperbranched star polymer. In one or more embodiments, the method comprises

(a) obtaining a core comprising a polyol;

(b) optional ly extending the core with one or more chain extenders to form an extended intermediate;

(c) reacting the core or the extended intermediate with a compound that comprises unsaturated free radical reaction sites to form the hyperbranched star polymer, the compound being selected from the group consisting of: an anhydride comprising one or more unsaturated groups, an epoxide comprising one or more unsaturated groups, and combinations thereof;

wherein the hyperbranched star polymer is radiation-curable. As used herein throughout the specification, the term "hyperbranched" refers to a polymer having at least three branches from, a core.

[0018] The hyperbranched polymer contains a central core from which the various branches containing sites of unsaturation radiate. In one or more embodiments, the core comprises a polyol . which has multiple reactive hydroxyI groups. As used herein, the term "polyol" refers to an alcohol having at least three hydroxyl functional groups available for reaction. The polyol may be selected from, triols, dimers of triols, tetrols, dimers tetrols, and sugar alcohols. Non-limiting examples of suitable polyols having three or more hydroxyl groups include glycerol, trimethylolmethane, trimcthylolcthanc, trimethylolpropane, 2,2,3-trimethylolbutane- 1 ,4-diol, 1 ,2,4-butanetriol, 1 ,2,6-hexanetriol, tris(hydroxymethyl)amine, tris( hydro\ycthyl)amine, tris(liydroxypropyl)amine, erythritol, pentaerythritol, diglycerol, triglyceroI or higher condensates of glycerol, d i ( t ri m ct h y I o l pro pan e ) , di(pentaerythritol), pentaerythritol ethoxylate, pentaerythritol propoxylate, tri shydroxymethyl isocyanurate, tris(hydroxyethyl) isocyan urate (THEIC), tris(hydroxypropyl) isocyanurate, inositols or sugars, such as glucose, fructose or sucrose, for example, sugar alcohols such as xylitol, sorbitol, mannitol, threitol, erythritol, adonitol (ribitol), arabitol (lyxitol), xylitol, duicitol (galactitol), maltitol, isomalt, polyetherols with a functionality of three or more, based on alcohols with a functionality of three reacted with ethylene oxide, propylene oxide and/or butylene oxide.

[0019] in some embodiments, examples of suitable polyols, include but are not limited to, trimethylolpropane. pentaerythritol, and a low molecular weight natural oil polyol. As used herein a "low molecular weight" natural oil polyol refers to one with a molecular weight of less than about 2500 or 2000 MW. Examples of suitable low molecular weight natural oil polyols include, but are not limited to, castor oil derivatives.

[0020] In one or more embodiments, the core further comprises a reaction product of the polyol and a di- or polyhydric acid. The core used in making the coating compositions can be prepared by a synthesis hav ing a step (a) of reacting a polyol comprising at least three hydroxyI groups with a di- or polyhydric acid. Non-limiting examples of suitable dihydric and polyhydric acids include d i m ethyl o l propi on i c acid, dimethylol propionic acid. ( DM PA), gluconic acid and lactobionic acid.

[002 1 ] After providing the core, the core may (b) optionally be extended with one or more chain extenders to form an extended intermediate. In this step, the unsaturated free radical reaction sites on the radial structures are extended further away from the core. In some embodiments, this extension is achieved by reacting the core with fully saturated anhydrides to create a multi-carboxyl-functional. hypcrbranched intermediate (termed the "extended intermediate"). This extension of the ev entual reactive unsaturation sites away from the core may be accomplished by the ring-opening reaction of ful ly saturated anhydrides w ith the hydroxyls of the core to provide the extended intermediate. The moles of fully saturated anhydride for extension would be < the equiv alents of hydroxide available for reaction on the core. This ring-opening reaction may be accomplished at 150°C or less to minimize undesirable cstcrification reactions and can optionally be aided by the use of catalysts. This extended intermediate is a multi-carboxyl functional hyperbranched intermediate. Non-limiting examples of suitable ful ly saturated anhydrides include h ex a h yd ro ph thaiic anhydride, succinic anhydride, phthalic anhydride, and methylhexahydrophthalic anhydride.

[0022] In one or more embodiments, the core is further extended by reacting a fully saturated epoxide functional material with the terminal carboxyl groups of the first intermediate to create a second extended intermediate now comprising reactive hydroxyI groups again. Suitable saturated epoxide materials for making this second extended intermediate include but are not limited to glycidyl neodecanoate and glycidyl neononanoate.

[0023 ] Subsequent to optional step (b), the core or the extended intermediate is reacted with a compound that comprises unsaturated free radical reaction sites to form the hyperbranched star polymer, the compound being selected from the group consisting of: an anhydride comprising one or more unsaturated groups, an epoxide comprising one or more unsaturated groups, and combinations thereof. The unsaturated groups allow the polymer to participate in radiation-initiated free radical polymerization reactions. One way to append unsaturated functionality to terminal hydroxy functionality on the core, or optionally an extended intermediate, is to react the desired number of equivalents of hydroxyI on the molecule with an appropriate number of moles of a suitable unsaturated anhydride through a ring-opening reaction accomplished at < 1 50°C to avoid undesirable cstcrification reactions. Catalysts can be employed to aid the progress of the reaction. Non- limiting examples of suitable unsaturated anhydrides include maleic anhydride, dimethylmaleic anhydride, dodecenylsuccinic anhydride, 2-octen-ylsuccinic anhydride, oleic anhydride and crucic anhydride.

[0024] One or more embodiments of the invention comprise appending the unsaturated functionality to terminal carboxyl ic acid functionality of an anhydride extended intermediate. This can be accomplished through the ring-opening reaction of an appropriate number of moles of an epoxide comprising one or more ethylenically unsaturated groups with the desired number of equivalents of carboxylic acid on the molecule. This ring-opening reaction may be accomplished at ≤ 150°C to avoid undesirable esterification reactions. Catalysts can be employed to aid the progress of the reaction. Non-limiting examples of unsaturated epoxide materials include glycidyl mcthacrylate, glycidyl acrylate and oleyl glycidyl ether.

[0025] Thus, in some embodiments, the method comprises extending the core with a first chain extender that is a fully saturated anhydride to provide a first extended intermediate. In one or more embodiments, the unsaturated anhydride is selected from the group consisting of malcic anhydride, dimethylmaleic anhydride, dodccenylsuccinic anhydride, 2-octen-ylsuccinic anhydride, oleic anhydride, erucic anhydride and combinations thereof.

[0026] The method may further comprise reacting the first extended intermediate with i. an unsaturated epoxide-functional compound or ii. a fully saturated epoxide- functional compound to provide a second extended intermediate comprising reactive hydroxyl groups, and reacting the second extended intermediate comprising reactive hydroxyI groups w ith an unsaturated anhydride to form the hyperbranched star polymer.

[0027] In embodiments pertaining to an unsaturated epoxide-functional compound, the unsaturated epoxide-functional compound may be selected from the group consisting of glycidyl mcthacrylate, glycidyl acrylate, oleyl glycidyl ether and combinations thereof.

[0028] In one or more embodiments, (b) comprises reacting the first extended intermediate with a fully saturated epoxide-functional compound to provide a second extended intermediate comprising reactive hydroxyl groups, and reacting the second extended intermediate comprising reactive hydroxyl groups w ith an unsaturated anhydride to form the hyperbranched star polymer. In further embodiments, the fully saturated epoxide-functional compound is selected from the group consisting of glycidyl neodecanoatc, glycidyl ncononanoate and combinations thereof.

[0029] In one or more embodiments, either the compound comprises the anhydride comprising one or more unsaturated groups that is directly reacted with the core or the core is extended w ith a chain extender that comprises a saturated anhydride that is directly reacted with the core. In some embodiments, the compound comprises an unsaturated anhydride comprising: malcic anhydride, dodccenylsuccinic anhydride, or combinations thereof. In one or more embodiments, the dicarboxylic acid comprises adipic acid, the polyol comprises trimethylolpropane and the compound comprises an unsaturated anhydride that is maleic anhydride. In some embodiments, the dicarboxylic acid comprises adipic acid, the polyol comprises trimethylolpropane and the compound comprises an unsaturated anhydride that is octenylsuccinic anhydride.

[0030] One or more of the methods described above provides a hyperbranched star polymer containing a branch point with multiple chains.

Coating compositions

[0031] The hyperbranched polymers of one or more embodiments of the invention may be formulated with other radiation-curable components and essential elements of radiation-curable coatings, (such as photoinitiators), applied to a substrate in accord with methods typical for radiation-cured coatings and cured utilizing actinic radiation appropriate to activate whichever photoinitiator is being used.

[0032] Accordingly, another aspect of the invention pertains to methods of producing a coating on a substrate surface, as well as to the coatings produced by these methods. As will be discussed further below, the method may comprise applying a coating composition comprising any one of the hyperbranched polymers described above to substrate surface. In further embodiments, the coating composition may further comprise a photoinitiator. In yet further embodiments, the method further comprises curing the polymer in situ by free radical polymerization (e.g. curing using actinic radiation).

[0033] A desired amount of any of the hyperbranched polyols described above may be included in a coating composition. The amount of the hyperbranched polyol included may vary depending on the characteristics of other coating components and the desired overall balance of performance characteristics of the coating obtained from the coating composition. In various examples, the coating composition may include from about 5% to about 60% by weight, or from about 5% to about 50% by weight, or from about 5% to about 45% by weight, or from about 10% to about 50% by weight, or from about 10% to about 45% by weight, or from about 10% to about 40% by weight, or from about 10% to about 35% by weight, or from about 15% to about 40% by weight, or from about 15% to about 35% by weight of the hyperbranched polyol based on the total amount of film- forming materials (also called the binder or vehicle of the coating composition).

[0034] The coating composition may include other reactive resins or polymers.

Examples of useful resins or polymers include (meth )acrylatc polymers (also known as acrylic polymers or resins), polyesters, polyethers, polyurethanes, polyols based on natural oils, such as those available under the trademark Pol veins from Vertci lus Specialties Inc., Indianapolis. IN, for example a polyol based on castor oil, polysiloxanes, and those described in Mormile et al., US Patent No. 5,578,675; Lane et al, US Patent Application Publication No. 201 1/0135,832; and Groenewolt et al, U.S. Patent Application Publication No. 2013/0136865, each of which is incorporated herein by reference. The other resins or polymers may have functionality reactive with the crosslinker for the hyperbranched polyol, or that the coating composition may contain a further crosslinker for the other resins or polymer. In certain preferred examples, the coating composition includes a further resin or polymer having hydroxyI groups, carbamate groups, or a combination of such groups. In various embodiments, the coating composition contains a hydroxyI- functional acrylic polymer, hydroxyl-functional polyester, or hydro xyl-functional polyurethane.

[0035] Polyvinyl polyols, such as acrylic (polyacrylate) polyol polymers that may be used as the h yd ro x y- f u n c t i o n a I material. Acrylic polymers or poiyacrylate polymers may be copolymers of both acrylic and mcthacrylic monomers as wel l as other copolymerizable vinyl monomers. The term "(meth)acryiate" is used for convenience to designate either or both acryIate, and mcthacrylate. and the term "(meth)acrylic" is used for convenience to designate either or both acrylic and mcthacryl ic.

[0036] I I yd ro x y l - c o n t a i n i n g monomers include hydroxy alkyl esters of acrylic or mcthacrylic acid. Non-limiting examples of h yd ro x y l - f u n c t i o n a I monomers include hydroxyethyl (meth )acrylate, hydroxypropyl (meth )acrviates. hydroxybutyl (meth)acrylates, hydroxyhexyl (meth)acrylates, propylene glycol mono(meth)acrylate, 2,3-dihydroxypropyl (meth)acrylate, pentaerythritol mono(meth)acrylate, polypropylene glycol mono(meth)acrylates, polyethylene glycol mono(meth)acrylates, reaction products of these with epsilon-caprolactone, and other hydroxyalkyl (meth)acrylates having branched or linear alkyl groups of up to about 10 carbons, and mixtures of these, where the term "(meth)acrylate" indicates either or both of the methacrylatc and aery I ate esters. Generally, at least about 5% by weight h yd r o x y I - f u n c t i o n a I monomer is included in the polymer. HydroxyI groups on a vinyl polymer such as an acryl ic polymer can be generated by other means, such as, for example, the ring opening of a glycidyl group, for example from copolymerized glycidyl methacrylatc. by an organic acid or an amine. HydroxyI functionality may also be introduced through thio-alcohol compounds, including, without limitation, 3-mcrcapto- 1 -propanol. 3-mercapto-2-butanol, 1 1 -mercapto- 1 -undecanol, I - mercapto-2-propanol, 2-mcrcaptoethanol, 6-mercapto- 1 -hexanol, 2-mcrcaptobcnzyl alcohol, 3-mercapto- 1 ,2-proanediol, 4-mercapto- 1 -butanol, and combinations of these. Any of these methods may be used to prepare a useful h yd rox y I - f u n c t i o n a I acrylic polymer.

[0037] Examples of suitable co-monomers that may be used include, without limitation, α,β-ethylenically unsaturated monocarboxylic acids containing 3 to 5 carbon atoms such as acryl ic, methacrylic, and crotonic acids and the alky I and cycloalkyl esters, nitriles, and amides of acrylic acid, methacrylic acid, and crotonic acid; α,β-cthylenically unsaturated dicarboxylic acids containing 4 to 34 carbon atoms and the anhydrides, monoesters. and diesters of those acids; vinyl esters, vinyl ethers, vinyl ketones, and aromatic or heterocyclic aliphatic vinyl compounds. Representative examples of suitable esters of acrylic, methacrylic. and crotonic acids include, without limitation, those esters from reaction with saturated aliphatic alcohols containing 1 to 20 carbon atoms, such as methyl, ethyl, propyl, isopropyl, n-butyl, isobutyi, tert-butyi, hexyl, 2-ethylhexyl, dodecyl, 3 ,3 ,5 - 1 ri met h y I hex y I , stearyl, lauryl, cyclohexyl, alkyl-substiruted cyclohexyl, alkanol- substituted cyclohexyl, such as 2-tert-butyl and 4-tert-butyl cyclohexyl, 4-cyclohexyl- l - butyl, 2-tert-butyl cyclohexyl, 4-tert-butyl cyclohexyl , 3,3,5,5,-tetraniethyl cyclohexyl, te t ra h yd ro fu r fu ry I , and isobornyl acrylates, methacrylates, and crotonates; unsaturated dialkanoic acids and anhydrides such as fumaric, maleic, itaconic acids and anhydrides and their mono- and diesters with alcohols such as methanol, ethanol, propanol, isopropanol . butanol, isobutanol. and tert-butanol. like maleic anhydride, maleic acid dimethyl ester and maleic acid monohexyl ester; vinyl acetate, vinyl propionate, vinyl ethyl ether, and vinyl ethyl ketone; styrene, a-methyl styrene, vinyl toluene, 2-vinyl pyrrol idone, and p- tert-butylstyrene. [0038] The acrylic polymer may be prepared using conventional techniques, such as by heating the monomers in the presence of a polymerization initiating agent and optionally a chain transfer agent. The polymerization may be carried out in solution, for example. Typical initiators are organic peroxides such as diaikyl peroxides such as di-t- butyl peroxide, peroxyesters such as t-butyl peroxy 2-ethylhexanoate, and t-butyl peracetate, peroxydicarbonates, diacyl peroxides, hydroperoxides such as t-butyi hydroperoxide, and peroxyketaIs; azo compounds such as 2,2'azobis(2- methylbutanenitrile) and 1 , 1 -azobis(cyclohexanecarbonitri le); and combinations of these. Typical chain transfer agents are mercaptans such as octyl mercaptan, n- or tert-dodecyl mercaptan; haiogenated compounds, thiosaiicyiic acid, mercaptoacetic acid, mercaptoethanol and the other thiol alcohols already mentioned, and dimeric alpha-methyl styrene.

[0039] The reaction is usually carried out at temperatures from about 20°C to about

200°C. The reaction may conveniently be done at the temperature at which the solvent or solvent mixture refluxes, although with proper control a temperature below the reflux may be maintained. The initiator should be chosen to match the temperature at which the reaction is carried out, so that the half-life of the initiator at that temperature should preferably be no more than about thirty minutes. Further details of addition polymerization generally and of polymerization of mixtures including (meth)acrylate monomers is readily available in the polymer art. The solvent or solvent mixture is generally heated to the reaction temperature and the monomers and initiator(s) are added at a controlled rate over a period of time, usually between 2 and 6 hours. A chain transfer agent or additional solvent may be fed in also at a controlled rate during this time. The temperature of the mixture is then maintained for a period of time to complete the reaction. Optionally, additional initiator may be added to ensure complete conversion.

[0040] Oligomeric and polymeric ethers may be used, including diethylene glycol, triethylene glycol, tetraethylene glycol, pentaethylene glycol, dipropylene glycol, tripropylene glycol, linear and branched polyethylene glycols, polypropylene glycols, and block, copolymers of poly(ethylene oxide-co-propylene oxide). Other polymeric polyols may be obtained by reacting a polyol initiator, e.g., a diol such as 1 ,3-propanediol or ethylene or propylene glycol or a polyol such as tri methy lo I propane or pentaerythritol, with a lactone or alkylene oxide chain-extension reagent. Lactones that can be ring opened by active hydrogen are well known in the art. Examples of suitable lactones include, without limitation, ε-caprolactone, γ-caprolactone, β-butyrolactone, β-proprio lactone, γ- butyrolactone, α-methyl-y-butyrolactone, β-methyl-y-butyrolaetone, γ-valerolactone, δ- valerolactone, γ-decanolactone, δ-decanolactone, y-nonanoic lactone, γ-octanoic lactone, and combinations of these. In one preferred embodiment, the lactone is ε-caprolactone. Useful catalysts include those mentioned above for polyester synthesis. Alternatively, the reaction can be initiated by forming a sodium salt of the hydroxyl group on the molecules that will react w ith the lactone ring. Similar polyester polyols may be obtained by reacting polyol initiator molecules with hydroxy acids, such as 1 2-hydro.xystearic acid.

[0041] In other embodiments, a polyol initiator compound may be reacted with an oxirane-containing compound to produce a polyether diol to be used in the polyurethane elastomer polymerization. Alkylene oxide polymer segments include, w ithout limitation, the polymerization products of ethylene oxide, propylene oxide, 1 ,2-cyclohexene oxide, 1 - butene oxide, 2-butene oxide, 1-hexene oxide, tert-butylethylene oxide, phenyl glycidyl ether, I -decene oxide, isobutylene oxide, cyclopentene oxide, 1 -pentene oxide, and combinations of these. The oxirane-containing compound is preferably selected from ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran. and combinations of these. The alkylene oxide polymerization is typically base-catalyzed. The polymerization may be carried out, for example, by charging the hydroxyl-functional initiator compound and a catalytic amount of caustic, such as potassium hydroxide, sodium methoxide, or potassium tcrt-butoxidc, and adding the alkylene oxide at a sufficient rate to keep the monomer available for reaction. Two or more different alkylene oxide monomers may be randomly copolymerized by coincidental addition or polymerized in blocks by sequential addition. Homopolymers or copolymers of ethylene oxide or propylene oxide are preferred. Tetrahydrofuran may be polymerized by a cat ionic ring-opening reaction using such counterions as SbF₆ ^-- , AsF₆ ^-- , PF₆ ^-- , SbCl₆ ^-- , BF₄ , CF3SO3^--, FSO3^--, and ClO ₄ ^--. Initiation is by formation of a tertiary oxonium ion. The polytetrahydrofuran segment can be prepared as a "living polymer" and terminated by reaction w ith the hydroxyl group of a diol such as any of those mentioned above. Polytetrahydrofuran is also known as polytetramethylene ether glycol (PTMEG). Any of the polyols mentioned above maybe employed as the polyol initiator and extended in this fashion.

[0042] Non-limiting examples of suitable polycarbonate polyols that might be used include those prepared by the reaction of polyols with dialkyl carbonates (such as diethyl carbonate), diphenyl carbonate, or dioxolanones (such as cyclic carbonates having five- and six-member rings) in the presence of catalysts like alkali metal, tin catalysts, or titanium compounds. Useful polyols include, without l imitation, any of those already mentioned. Aromatic polycarbonates arc usually prepared from reaction of bisphenols, e.g., bisphenol A, with phosgene or diphenyl carbonate. Aliphatic polycarbonates may be preferred for a higher resistance to yel lowing, particularly when the carbamate - functional, material is used in an automotive OEM or refinish topcoat.

[0043] Polyesters polyols may be prepared by reacting: (a) polycarboxylic acids or their esterifiable derivatives, together if desired with monocarboxylic acids, (b) polyols, together if desired with monofunctional alcohols, and (c) if desired, other modifying components. Non-limiting examples of polycarboxylic acids and their esterifiable derivatives include phthalic acid, isophthalic acid, terephthalic acid, halophthalic acids such as tetrachloro- or tetrabromophthalic acid, adipic acid, glutaric acid, azelaic acid, scbacic acid, fumaric acid, malcic acid, trimellitic acid, pyromellitic acid, tetrahydrophthalic acid, hexahydrophthalic acid. 1 ,2-cyciohexancdicarboxlic acid, 1 ,3- eyclohcxanc-discarboxlic acid. 1 ,4-cycIohexane-dicarboxlic acid, 4- m e t h yl h ex ah yd rophthali c acid, cndomethylenetetrahydropthalic acid, tricyciodccanc- dicarboxlic acid, endoethylenehexahydropthalic acid, camphoric acid, cyclohexanetetracarboxlic acid, and cyclobutanetetracarboxylic acid. The cycloaliphatic polycarboxylic acids may be employed either in their cis or in their trans form or as a mixture of the two forms. Esterifiable derivatives of these polycarboxylic acids include their single or multiple esters with aliphatic alcohols having I to 4 carbon atoms or hydroxy alcohols having up to 4 carbon atoms, preferably the methyl and ethyl ester, as well as the anhydrides of these polycarboxylic acids, where they exist. Non-l imiting examples of suitable monocarboxylic acids that can be used together with the polycarboxylic acids include benzoic acid, tert-butylbenzoic acid, lauric acid, isonoanoic acid and fatty acids of naturally occurring oils. Non-limiting examples of suitable polyols include any of those already mentioned above, such as ethylene glycol, butylene glycol, neopentyl glycol, propanediols, butanediols, hexanediols, diethylene glycol, cyclohcxancdiol, cy c I o h ex an ed i m et ha n o I , trimethylpentanediol, ethy lb u t y I p ro pa n ed i o I ditrimethylolpropane, trimethylolethane, trimcthylol propane, glycerol, pentaerythritol, dipentacrythritol. tris-hydroxyethyl isocyanate, polyethylene glycol, polypropylene glycol, and polyols derived from natural oils. Non-limiting examples of monoalcohols that may be used together with the polyols include butanol. octanol. lauryl alcohol, and cthoxylatcd and propoxyIatcd phenols. Non-limiting examples of suitable modifying components include compounds which contain a group which is reactive with respect to the functional groups of the polyester, including polyisocyanates and/or diepoxide compounds, and also if desired, monoisocyanatcs and/or monoepoxidc compounds. The polyester polymerization may be carried out by known standard methods. This reaction is conventionally carried out at temperatures of between 180 °C and 280 °C, in the presence if desired of an appropriate esterification catalyst. Typical catalysts for the esterification polymerization are protonic acids, Lewis acids, titanium alkoxides, and dialkyltin oxides, for example lithium octanoatc. dibutyltin oxide, dibutyltin dilaurate, para-tolucnesul fonic acid under reflux with small quantities of a suitable solvent as entraining agent such as an aromatic hydrocarbon, for example xylene, or a (cyclo)aliphatic hydrocarbon, for example cyclohexanc.

[0044] Polyurethanes having hydroxyI functional groups may also be used in the coating compositions along with the hyperbranched polyol. Examples of suitable polyurethane polyols include polyestcr-polyurcthancs, polyether-polyurethanes. and polycarbonate -polyurethanes, including, without limitation, polyurethanes polymerized using as polymeric diol reactants polyethers and polyesters including po I ycapro lactone polyesters or polycarbonate diols. These polymeric diol-based polyurethanes are prepared by reaction of the polymeric diol (polyester diol, po I yet her diol, polycaprolactone diol, po I yte t ra h yd ro fu ran diol, or polycarbonate diol), one or more polyisocyanates, and, optional ly, one or more chain extension compounds. Chain extension compounds, as the term is being used, are compounds having two or more functional groups, preferably two functional groups, reactive with isocyanate groups, such as the diols, amino alcohols, and diamines. Preferably the polymeric diol-based polyurethane is substantially linear (i.e., substantially ail of the reactants are difunctionai).

[0045] Diisocyanates used in making the polyurethane polyols may be aromatic, aliphatic, or cycloaliphatic. Useful di isocyanate compounds include, without limitation, isophoronc diisocyanate (IPDI), methylene bis-4-cyclohcxyl isocyanate (H₁₂MDI), cyclohexyl diisocyanate (CHDI), m-tctramcthyl xylene diisocyanate (m-TMXDI), p- tetramethyl xylene diisocyanate (p-TMXDI), 4,4 '-methylene diphenyl diisocyanate (MDI, also known as 4,4'-diphenylmethane diisocyanate), 2,4- or 2,6-toluene diisocyanate (TDI), ethylene diisocyanate, 1 ,2-diisocyanatopropanc, 1 ,3-diisocyanatopropanc, 1 ,6- diisocyanatohexane (hexamethylene diisocyanate or H D I) , 1 ,4-butylene diisocyanate, lysine diisocyanate, meta-xylyienediioscyanate and pa ra-x y I y l e n ed i i so c ya na t e , 4-chioro- 1 ,3-phenylene diisocyanate, 1 ,5-tetrahydro-naphthaiene diisocyanate, 4,4'-dibenzyi diisocyanate, and xyiylene diisocyanate (XDI), and combinations of these. Non-limiting examples of higher-functionality polyisocyanates that may be used in limited amounts to produce branched thermoplastic polyurethanes (optionally along with monofunctionai alcohols or monofunctionai isocyanates) include 1 ,2,4-bcnzcne triisocyanate, 1 ,3,6- hexamethylenc triisocyanate. 1 ,6,1 1 -undecane triisocyanate, bicycloheptane triisocyanate. triphenylmethane-4,4',4"-triisocyanate, isocyanurates of diisocyanates, biurets of diisocyanates, ailophanates of diisocyanates, and the like.

[0046] In various embodiments, the polymeric diol preferably has a weight average molecular weight of at least about 500, more preferably at least about 1 000. and even more preferably at least about 1800 and a w eight average molecular weight of up to about 10,000, but polymeric diols having weight average molecular weights of up to about 5000, especially up to about 4000, may also be preferred. The polymeric diol advantageously has a weight average molecular weight in the range from about 500 to about 10.000, preferably from about 1 000 to about 5000, and more preferably from about 1 500 to about 4000. The weight average molecular weights may be determined by ASTM D-4274. [0047] The reaction of the polyisocyanate, polymeric diol, and diol or other chain extension agent is typically carried out at an elevated temperature in the presence of a suitable catalyst, for example tertiary amines, zinc salts, and manganese salts. The ratio of polymeric diol, such as polyester diol, to extender can be varied within a relatively wide range depending largely on the desired hardness or flexibility of the final polyurethane elastomer. For example, the equivalent proportion of polyester diol to extender may be within the range of 1 :0 to 1 : 12 and, more preferably, from 1 : 1 to 1 :8. Preferably, the diisocyanate(s) employed are proportioned such that the overall ratio of equivalents of isocyanate to equivalents of active hydrogen containing materials is within the range of 1 : 1 to 1 : 1.05, and more preferably, 1 : 1 to 1 : 1 .02. The polymeric diol segments typically are from about 35% to about 65% by weight of the polyurethane polymer, and preferably from about 35% to about 50% by weight of the polyurethane polymer.

[0048] A polysiloxane polyol may be made by hydrosi Mating a polysiloxane containing silicon hydrides with an alkyenyl polyoxyaikylene alcohol containing two or three terminal primary hydroxyI groups, for example allylic polyoxyaikylene alcohols such as trimethylolpropane monoallyl ether and pentaerythritol monoallyl ether.

[0049] Any of the polyol resins and polymers described above may be derivatized to have carbamate groups according to known methods, for example by reaction of a hydroxyl-functional material w ith an aikyl carbamate, for example methyl carbamate or butyl carbamate, through what is referred to as "transcarbamation" or "transcarbamoylation." In other methods of forming c a r ba m a t e - f u n c t i o n a I resins and polymers for use in the coating compositions, the resin and polymers may be polymerized using a carbamate- functional monomer.

[0050] The coating composition containing the hyperbranched polyol. and optional further active hydrogen-functional resin or polymer also includes at least one crosslinker or curing agent reactive with hydroxyI groups, such as aminoplast crosslinkers having active methylol, methylalkoxy or butvlalkoxy groups; polyisocyanate crosslinkers, which may have blocked or unblocked isocyanate groups; polyanhydrides; and polyepoxide functional crosslinkers or curing agents, w hich could be reactive with the hydroxyls as well as with carboxylic acid groups the hyperbranched polyols. [0051] Aminoplasts, or amino resins, are described in Encyclopedia of Polymer

Science and Technology vol. 1 , p. 752-789 (1985), the disclosure of which is hereby incorporated by reference. An aminopiast is obtained by reaction of an activated nitrogen with a lower molecular weight aldehyde, optional ly with further reaction with an alcohol (preferably a mono-alcohol with one to four carbon atoms such as methanol, isopropanol, n-butanol, isobutanol, etc.) to form an ether group. Preferred examples of activated nitrogens arc activated amines such as meiamine. benzoguanamine, eye I o hex y l ca rboguan am i ne, and acetoguanamine; ureas, including urea itself, thiourea, ethyleneurea, dihydroxyethyleneurea, and guanylurea; giycolurii; amides, such as dicyandiamide; and carbamate-functionai compounds having at least one primary carbamate group or at least two secondary carbamate groups. The activated nitrogen is reacted with a lower molecular weight aldehyde. The aldehyde may be selected from formaldehyde, acetaldehyde, crotonaldehyde, benzaldehyde, or other aldehydes used in making aminopiast resins, al though formaldehyde and acetaldehyde, especial ly formaldehyde, are preferred. The activated nitrogen groups are at least partial ly aikylolated w ith the aldehyde, and may be fully aikylolated; preferably the activated nitrogen groups are fully aikylolated. The reaction may be catalyzed by an acid, e.g. as taught in U.S. Patent No. 3,082,180, which is incorporated herein by reference.

[0052] The optional alkyiol groups formed by the reaction of the activated nitrogen with aldehyde may be partial ly or fully etherified with one or more monofunctional alcohols. Suitable examples of the monofunctional alcohols include, without limitation, methanol, ethanol. n-propanol. isopropanol. n-butanol, isobutanol. tert- biityl alcohol , benzyl alcohol , and so on. Monofunctional alcohols hav ing one to four carbon atoms and mixtures of these are preferred. The etherification may be carried out, for example, the processes disclosed in U.S. Patents No. 4,105,708 and 4,293,692 incorporate the disclosures of which incorporated herein by reference. The aminopiast may be at least partially etherified, and in various embodiments the aminopiast is fully etherified. For example, the aminopiast compounds may hav e a plurality of methylol and/or etherified methylol, butylol, or alkyiol groups, w hich may be present in any combination and along with unsubstituted nitrogen hydrogens. Examples of suitable curing agent compounds include, without limitation, melaminc formaldehyde resins, including monomeric or polymeric melaminc resins and partially or fully alkylated melaminc resins, and urea resins (e.g., methylol ureas such as urea formaldehyde resin, and alkoxy ureas such as butylated urea formaldehyde resin). One Non-limiting example of a fully etherified melaminc- fo rm a l d e h yd c resin is hexamethoxymethyl melaminc.

[0053] The alkylol groups are capable of self-reaction to form oligomeric and polymeric aminoplast crossliiiking agents. Useful materials are characterized by a degree of polymerization. For melaminc formaldehyde resins, it is preferred to use resins having a number average molecular weight less than about 2000, more preferably less than 1500, and even more preferably less than 1000.

[0054] A coating composition including aminoplast crossliiiking agents may further include a strong acid catalyst to enhance the cure reaction. Such catalysts are well known in the art and include, for example, para-toluenesulfonic acid, dinonylnaphthalene disulfonic acid, dodecylbenzenesulfonic acid, phenyl acid phosphate, monobutyl maleate, butyl, phosphate, and hydroxy phosphate ester. Strong acid catalysts are often blocked, e.g. with an amine.

[0055] Particularly for refinish coatings, polyisocyanate crosslinkers are commonly used. Examples of suitable polyisocyanate crosslinkers include, without limitation, alkylene polyisocyanates such as hexamethylene diisocyanate, 2,2,4- and/or 2,4,4-trimethylhexamethylene diisocyanate, dodecamethylene diisocyanate, 1 ,4- diisocyanatocyclohexane, l -isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane (isophorone diisocyanate), 2,4'- and/or 4,4'-diisocyanatodicyclohexylmethane, 3- isocyanato-methyl-3,5,5-trimethyl cyclohexyl isocyanate, aromatic polyisocyanates such as 2,4'- and/or 4,4 '-d i isocyanatocl i phenyl met hane, 2,4- and/or 2,6-diisocyanatotoluene, naphthylene diisocyanate, and mixtures of these polyisocyanates. Generally, polyisocyanates having three or more isocyanate groups are used; these may be derivatives or adducts of diisocyanates. Useful polyisocyanates may be obtained by reaction of an excess amount of an isocyanate with water, a polyol (for example, ethylene glycol, propylene glycol, 1 ,3-butylene glycol, neopentyl glycol, 2.2,4-trimethyl- 1 ,3-pentane diol, hexamethylene glycol, cyclohexane dimethanol, hydrogenated bisphenol A, trimethylolpropane, trimethylolethane, 1 ,2,6-hexanetriol, glycerine, sorbitol or pcntaerythritol ), or by the reaction of the isocyanate with itself to give an isocyanurate.

Examples include b i u ret -gro up- co n t a inin g polyisocyanates, such as those described, for example, in U.S. Pat. No. 3,124,605 and U.S. Pat. No. 3,201 ,372 or DE-OS 1 ,101 ,394; isocyanurate-group-containing polyisocyanates, such as those described, for example, in U.S. Pat. No. 3,001 ,973, DE-PS 1 ,022,789, 1 ,222,067 and 1 ,027,394 and in DE-OS 1 ,929,034 and 2,004,048; urethane-group-containing polyisocyanates, such as those described, for example, in DE-OS 953,012, BE-PS 752,261 or U.S. Pat. Nos. 3,394,164 and 3,644,457; carbodiimide group-containing polyisocyanates, such as those described in DE-PS 1 ,092,007, U.S. Pat. No. 3,152,162 and DE-OS 2,504,400, 2,537,685 and 2,552,350; allophanate group-containing polyisocyanates, such as those described, for example, in GB-PS 994,890, BE-PS 761 ,626 and N L-OS 7,102,524; and uretdione group- containing polyisocyanates, such as those described in EP-A 0,377,177, each reference being incorporated herein by reference.

[0056] Such isocyanate crosslinkers for refinish coating compositions are commonly stored separately and combined with the h yd ro x y I - f u n c t i o n a l film-forming components shortly before application. For example, a two-part or two-pack or two- component refinish coating composition may include in a crosslinking part, package, or component one of aliphatic biurets and isocyanurates, such as the isocyanurates of hexamethylene diisocyanate and isophorone diisocyanate.

[0057] Curing catalysts for the urethane reaction such as tin catalysts can be used in the coating composition. Typical examples are without limitation, tin and bismuth compounds including dibutyltin dilaurate, dibutyltin oxide, and bismuth octoate. When used, catalysts are typically present in amounts of about 0.05 to 2 percent by weight tin based on weight of total nonvolatile vehicle.

[0058] A dianhydride may also be used to crosslink the hyperbranchcd polyol.

Non-limiting examples of di-cyciic carboxylic anhydrides include pyromellitic dianhydride, ethylenediaminetetraacetic dianhydride, cyclobutane- 1 ,2,3,4-tetracarboxyl ic dianhydride, 3,3',4,4'-biphenyltetracarboxylic dianhydride, tetrahydrofurane-2,3,4,5- tetracarboxylic dianhydride, and cyciohexane-l ,2,4,5-tetracarboxyiic acid dianhydride. [0059] Polyepoxide crosslinking agents include acrylic polymers having epoxide groups, for example copolymers of al lyI giycidyl ether, glycidyl acryiate, or glycidyl methacrylate, as well as polyglycidyl esters and ethers of polyol and polycarboxyiic acids.

[0060] The coating composition made with the hypcrbranclicd poiyol may further include solvents, pigments, fillers, or customary additives.

[0061 ] A solvent may optional ly be utilized in the coating compositions. Although the coating composition may be formulated, for example, in the form of a powder, it is often desirable that the composition be in a substantially liquid state, which can be accomplished with the use of a solvent to either dissolve or disperse the hyperbranched polyol, crosslinker, and other film-forming material, or materials. In general, depending on the solubility characteristics of the components, the solvent can be any organic solvent and/or water. In one preferred embodiment, the solvent is a polar organic solvent. For example, the solvent may be a polar aliphatic solvent or polar aromatic solvent. Among useful solvents are ketone, ester, acetate, aprotic amide, aprotic sul foxide, and aprotic amine solvents. Examples of specific useful solvents include ketones, such as acetone, methyl ethyl ketone, methyl amyI ketone, methyl isobutyl ketone, esters such as ethyl acetate, butyl acetate, pentyl acetate, ethyl ethoxypropionate, ethylene glycol butyl ether acetate, propylene glycol monomethyl ether acetate, aliphatic and/or aromatic hydrocarbons such as toluene, xylene, solvent naphtha, and mineral spirits, ethers such as glycol ethers like propylene glycol monomethyl ether, alcohols such as ethanol, propanol. isopropanol, n-butanol, isobutanol. and tert-butanol. nitrogen-containing compounds such as N-methyl pyrrolidone and N-ethyl pyrrolidone, and combinations of these. In example embodiments, the liquid medium is water or a mixture of water with small amounts of organic water-soluble or water-miscible co-solvents. The solvent in the coating composition may be present in an amount of from, about 0.01 weight percent to about 99 weight percent, or in an amount of from about 10 weight percent to about 60 weight percent, or in an amount of from about 30 weight percent to about 50 weight percent.

[0062] When the coating compositions are formulated as basecoat topcoats, monocoat topcoats, or primers they contain pigments and fillers, including special effect pigments. Non-limiting examples of special effect pigments that may be utilized in basecoat and monocoat topcoat coating compositions include metallic, pearlescent, and color-variable effect flake pigments. Metallic (including pearlescent, and color-variable) topcoat colors are produced using one or more special flake pigments. Metallic colors are generally defined as colors having gonioapparent effects. For example, the American Society of Testing Methods (ASTM) document F284 defines metallic as "pertaining to the appearance of a gonioapparent material containing metal flake." Metallic basecoat colors may be produced using metallic flake pigments like aluminum flake pigments, coated aluminum flake pigments, copper flake pigments, zinc flake pigments, stainless steel flake pigments, and bronze flake pigments and/or using pearlescent flake pigments including treated micas like titanium dioxide-coated mica pigments and iron oxide-coated mica pigments to give the coatings a different appearance (degree of reflectance or color) when viewed at different angles. Metal flakes may be cornflake type, lenticular, or circulation- resistant; micas may be natural, synthetic, or aluminum oxide type. Flake pigments do not agglomerate and are not ground under high shear because high shear would break or bend the flakes or their crystalline morphology, diminishing or destroying the gonioapparent effects. The flake pigments are satisfactorily dispersed in a binder component by stirring under low shear. The flake pigment or pigments may be included in the high solids coating composition in an amount of about 0.01 wt.% to about 50 wt.% or about 1 5 wt.% to about 25 wt.%, in each case based on total binder weight . Non-limiting examples of commercial flake pigments include PALIOCROME® pigments, available from BASF Corporation.

[0063] Non-limiting examples of other suitable pigments and fillers that may be utilized in basecoat and monocoat topcoat coating compositions include inorganic pigments such as titanium dioxide, barium sulfate, carbon black, ocher, sienna, umber, hematite, limonite, red iron oxide, transparent red iron oxide, black iron oxide, brown iron oxide, chromium oxide green, strontium chromate. zinc phosphate, silicas such as fumed silica, calcium carbonate, talc, barytes, ferric ammonium ferrocyanide (Prussian blue), and ultramarine, and organic pigments such as metallized and non-metal lized azo reds, quinacridone reds and violets, perylene reds, copper phthaiocyanine blues and greens, carbazole violet, monoaryl ide and diaryiide yellows, benzimidazolone yellows, tolyl orange, naphthol orange, nanoparticles based on silicon dioxide, aluminum oxide or zirconium oxide, and so on. The pigment or pigments arc preferably dispersed in a resin or polymer or with a pigment dispersant, such as binder resins of the kind already described, according to known methods. In general, the pigment and dispersing resin, polymer, or dispersant are brought into contact under a shear high enough to break the pigment agglomerates down to the primary pigment particles and to wet the surface of the pigment particles with the dispersing resin, polymer, or dispersant. The breaking of the agglomerates and wetting of the primary pigment particles arc important for pigment stability and color development. Pigments and fillers may be utilized in amounts typical ly of up to about 60% by weight, based on total weight of the coating composition. The amount of pigment used depends on the nature of the pigment and on the depth of the color and. or the intensity of the effect it is intended to produce, and also by the dispersibility of the pigments in the pigmented coating composition. The pigment content, based in each case on the total weight of the pigmented coating composition, is preferably 0.5% to 50%, more preferably 1% to 30%, very preferably 2% to 20%, and more particularly 2.5% to 10% by weight.

[0064] Clearcoat coating compositions typically include no pigment, but may include small amount of colorants or fillers that do not unduly affect the transparency or desired clarity of the clearcoat coating layer produced from the composition.

[0065] Additional desired, customary coating additives agents may be included, for example, surfactants, stabilizers, wetting agents, dispersing agents, adhesion promoters, UV absorbers, hindered amine light stabilizers such as HALS compounds, benzotriazoles or oxalanilides; free-radical scavengers; slip additives; defoamers; reactive diluents, of the kind which arc common knowledge from the prior art; wetting agents such as siioxanes, fluorine compounds, curboxylic monocsters. phosphoric esters, polyacrylic acids and their copolymers, for example polybutyl acrylate, or polyurcthanes; adhesion promoters such as tricyclodccanedimethanol; flow control agents; film-forming assistants such as cellulose deriv atives; rh oology control additives, such as the additives known from patents WO 94/22968, EP-A-0 276 501 , EP-A-0 249 201 or WO 97/ 1 2945; crossiinked polymeric microparticles, as disclosed for example in EP-A-0 008 127; inorganic phyllosiiicates such as a I u m i n u m - m a g n e s i u m silicates, sodium-magnesium and sodium-magnesium-fluorine- lithium phyliosilicates of the montmorillonitc type; silicas such as Aerosils®.; or synthetic polymers containing ionic and/or associative groups such as polyvinyl alcohol, pol y( met h )acry I am i de, poiy(meth)acryiic acid, polyv inyl pyrrol idone, styrene-maieic anhydride copolymers or cthylcnc-malcic anhydride copolymers and their derivatives, or hydrophobically modified ethoxyiated urcthanes or polyacrylates; flame retardant; and so on. Typical coating compositions include one or a combination of such additives.

[0066] Coating compositions can be coated by any of a number of techniques well known in the art. These include, for example, spray coating, dip coating, roll coating, curtain coating, knife coating, spreading, pouring, dipping, impregnating, trickling or rolling, and the like. For automotive body panels, spray coating is typically used. Preference is given to employing spray application methods, such as compressed-air spraying, airless spraying, high-speed rotation, electrostatic spray application, alone or in conjunction w ith hot spray application such as hot-air spraying, for example.

[0067] The coating compositions and coating systems of the invention are employed in particular in the technologically and esthetically particularly demanding field of automotive OEM finishing and also of automotive re finish. The coating compositions can be used in both single-stage and multistage coating methods, particularly in methods where a pigmented basecoat or monocoat coating layer is first applied to an uncoated or precoated substrate and afterward another coating layer may optionally be applied when the pigmented film is a basecoat coating. The invention, accordingly, also provides multicoat coating systems comprising at least one pigmented basecoat and may have least one clearcoat disposed thereon, wherein either the clearcoat or the basecoat has been or both have been produced from the coating composition containing the hyperbranched polyol as disclosed herein. Both the basecoat and the clearcoat coating composition can include the disclosed hyperbranched polyol.

[0068] The applied coating compositions can be cured after a certain rest time or

"flash" period. The rest time serves, for example, for the leveling and devolatilization of the coating films or for the evaporation of volatile constituents such as solvents. The rest time may be assisted or shortened by the application of elevated temperatures or by a reduced humidity, provided this does not entail any damage or alteration to the coating films, such as premature complete crosslinking, for instance.

[0069] In one or more embodiments, the coating compositions described herein are advantageously cured via radiation. In such cases, the coating compositions may comprise a photoinitiator. In further embodiments, the photoinitiator is selected from the group consisting of diaryI ketone derivatives, benzoi n alkyl. ethers, alkoxy phenyl ketones, 0- acylated oximinoketones, polycyclic quinoncs. benzophenones and substituted benzophenones, xanthones, thioxanthoncs. chiorosuifonyl and chioromethyl polynuciear aromatic compounds, chiorosuifonyl and ch ioromethyl heterocyclic compounds, chiorosuifonyl and chioromethyl benzophenones and fluorenones, haioalkanes and combinations thereof.0020

[0070] While the coatings described herein are advantageously cured via radiation, it is also possible to utilize thermal curing. The thermal curing of the coating compositions has no peculiarities in terms of method but instead takes place in accordance with the typical, known methods such as heating in a forced-air ov en or irradiation with I R lamps. The thermal cure may also take place in stages. Another preferred curing method is that of curing with near infrared (NIR) radiation . Although various methods of curing may be used, heat curing is preferred. Generally, heat curing is effected by exposing the coated article to elevated temperatures provided primari ly by radiative heat sources. After application, the applied coating layer is cured, for example with heat at temperatures from 30 to 200° C, or from 40 to 190° C, or from 50 to 180° C, for a time of 1 min up to 10 h, more preferably 2 min up to 5 h, and in particular 3 min to 3 h, al though longer cure times may also be employed at the temperatures employed for automotive re finish, which are preferably between 30 and 90° C. The hyperbranched polyol can be used for both refinish coatings and for original finish coatings that are cured at higher temperatures. A typical method for applying a refinish coating composit ion includes application and drying wit h cure at room temperature or at an elev ated temperature between 30 and 90° C. OEM coatings are typically cured at higher temperatures, for example from about I 1 0 to about 135 °C. The curing time wil l vary depending on the particular components used, and physical parameters such as the thickness of the layers, however, typical curing times range from about 15 to about 60 minutes, and preferably about 15-25 minutes for blocked acid catalyzed systems and about 10-20 minutes for unblocked acid catalyzed systems.

[0071] Cured basecoat layers formed may have a thickness of from about 5 to about

75 μιη, depending mainly upon the color desired and the thickness needed to form a continuous layer that will provide the color. Cured clearcoat layers formed typically have thicknesses of from about 30 μηι to about 65 μηι.

[0072] The coating composition can be applied onto many different types of substrates, including metal substrates such as bare steel, phosphated steel, galvanized steel, or aluminum; and non-metallic substrates, such as plastics and composites. The substrate may also be any of these materials having upon it already a layer of another coating, such as a layer of an electrodeposited primer, primer surfacer, and/or basecoat, cured or uncured.

[0073] The substrate may be first primed with an electrodeposition (electrocoat) primer. The electrodeposition composition can be any electrodeposition composition used in automotive vehicle coating operations. Non-limiting examples of electrocoat compositions include electrocoating compositions sold by BASF. Electrodeposition coating baths usually comprise an aqueous dispersion or emulsion including a principal film-forming epoxy resin having ionic stabilization (e.g., salted amine groups) in water or a mixture of water and organic cosolvcnt. Emulsified with the principal film- forming resin is a crosslinking agent that can react with functional groups on the principal resin under appropriate conditions, such as with the application of heat, and so cure the coating. Suitable examples of crosslinking agents, include, without limitation, blocked polyisocyanates. The electrodeposition coating compositions usually include one or more pigments, catalysts, plasticizers, coalescing aids, ami foaming aids, flow control agents, wetting agents, surfactants, UV absorbers, HALS compounds, antioxidants, and other additives.

[0074] The electrodeposition coating composition is preferably applied to a dry film thickness of 10 to 35 μηι . After application, the coated vehicle body is removed from the bath and rinsed with deionized water. The coating may be cured under appropriate conditions, for example by baking at from about 135° C. to about 190° C. for between about 15 and about 60 minutes. [0075] Because the coatings of the invention produced from the coating compositions of the invention adhere excellently even to eiectrocoats, surfacer coats, basecoat systems or typical, known clearcoat systems that have already cured, they are suitable not only for use in automotive OEM finishing but also for automotive refill ish or for the modular scratchproofing of automobile bodies that have already been painted.

[0076] Yet another aspect of the invention pertains to the coatings comprising the hyperbranched polymers as described herein and'or coatings produced by the methods described herein. Such coatings are distinct from previously known coatings because of the polymer bridging, which has additional degrees of freedom in the cured state. The coating may be analyzed according to methods known in the art to determine the types of linkages present. There may also be residual photoinitiator decomposition products, which are not present in coatings cured thermally or by methods other than radiation curing.

[0077] Reference throughout this specification to "one embodiment," "certain embodiments," "various embodiments," "one or more embodiments" or "an embodiment" means that a particular feature, structure, material, or characteristic described in connection with the embodiment is included in at least one embodiment of the invention. Thus, the appearances of the phrases such as "in one or more embodiments," "in certain embodiments," "in various embodiments," "in one embodiment" or "in an embodiment" in various places throughout this specification are not necessarily referring to the same embodiment of the invention. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in one or more embodiments.

[0078] The fol lowing examples illustrate, but do not in any way limit, the scope of the methods and compositions as described and claimed. A ll parts are parts by weight unless otherwise noted.

EXAMPLES

[0079] Example 1 - Synthesis of a hyperbranched star polyester

[0080] Core Synthesis

[0081] The components in Table 1 below were combined

[0082] The mixture was heated to 1 15°C and exotherm observed. ( Avoid temperature above 149°C.) After peak, the mixture was heated to 136°C, then cooled to about 90°C.

[0083] HHPA (9.839 wt% (pre-meited@ 60°C)) was added and the reaction mixture flushed with Aromatic 1 00 (0.621 wt%). The mixture was heated to 1 15°C and the exotherm observed. After peaking, the mixture was heated to 145°C, (av oid temperatures above 149°C), processed at 145°C for 90 minutes, then cooled to 140°C.

[0084] Extension and Modification

[0085] 23.662 wt% glycidyl neodecanoate was added to the reaction mixture over 60-90 minutes, then Aromatic 100 (0.694 wt%) was used to flush the mixture. Then, the mixture was heated to 145 °C, and processed at 145 °C for 1 50 minutes and cooled to 1 1 5 °C.

[0086] Reducer

[0087] The reaction was reduced with 1.631 wt% each of Aromatic 100 and Xylene

[0088] Adding Unsaturated Functional ity

[0089] 36.280 wt% dodecenyisuccinic anhydride (DDSA) was added to the reaction mixture over 30-60 minutes, and then the mixture was flushed with 1 0.003 wt%

Aromatic 100. The reaction mixture was processed at 1 15 °C to target acid value, indicating essentially ail anhydride had reacted.

[0090] A representation of the star polyester partially extended and modified with gl ycidyl neodecanoate with unsatu ration from DDSA is show n in FIG. 1.

[0091] Example 2 - Coating Formulation

[0092] The product example I was incorporated into a coating formulation. A coating was prepared with ingredients as follows: (by wt )

[0093] The resulting coating formulation was then applied to a metal substrate and exposed to actinic radiation and subsequently cured completely to form a cohesive film coating on the metal.

[0094] The foregoing description of the embodiments has been provided for purposes of illustration and description. It is not intended to be exhaustive or to limit the invention. Individual elements or features of a particular embodiment are generally not limited to that particular embodiment, but, where applicable, are interchangeable and can be used in a selected embodiment, even if not specifically shown or described. The same may also be varied in many ways. Such variations are not to be regarded as a departure from the invention, and all such modifications are intended to be included within the scope of the invention.

Claims

CLA IM S

What is claimed is:

I . A method of making a hyperbranched star polymer, the method comprising:

(a) obtaining a core comprising a pol yol ;

(b) optionally extending the core with one or more chain extenders to form an extended intermediate;

(c) reacting the core or the extended intermediate with a compound that

comprises unsaturated free radical reaction sites to form the hyperbranched star polymer, the compound bei ng selected from the group consisting of: an anhydride comprising one or more unsaturated groups, an epoxide comprising one or more unsaturated groups, and combinations thereof;

wherein the hyperbranched star polymer is radiation-curable.

2. The method of claim 1 , wherein either the compound comprises the anhydride comprising one or more unsaturated groups that is directly reacted with the core or the core is extended with a chain extender that comprises a saturated anhydride that is directly reacted with the core.

3. The method of claim 1 , wherein the polyol is selected from the group consisting of tr i m et h y I o I p ro pane, pentaerythritol. a low molecular weight natural oi l polyol, and combinations thereof.

4. The method of claim 1 , w herein the core further comprises a reaction product of the polyol and a di- or polyhydric acid.

5. The method of claim 4, wherein the di-hydric acid comprises dimethylol propionic acid.

6. The method of claim 1 , wherein the compound comprises an unsaturated anhydride selected from the group consisting of maleic anhydride, dimet hyl maleic anhydride, dodeeenylsuccinie anhydride, 2-octen-ylsuccinic anhydride, oleic anhydride, erucic anhydride and combinations thereof.

7. The method of claim 1 , wherein the method comprises:

(a) extending the core with a first chain extender that is a fully saturated

anhydride to provide a first extended intermediate;

(b) reacting the first extended intermediate with

i. an unsaturated cpoxide-functional compound or ii. a fully saturated cpoxide-functional compound to prov ide a second extended intermediate comprising reactive hydroxyI groups, and reacting the second extended intermediate comprising reactive hydroxyl groups with an unsaturated anhydride to form the hyperbranched star polymer.

8. The method of claim 7, wherein the saturated anhydride is selected from the group consisting o f h ex a h yd ro ph t h a I i c anhydride, succinic anhydride, phthalic anhydride, met h y l h exah ydro phthalic anhydride and combinations thereof.

9. The method of claim 7, wherein (b) comprises reacting the first extended intermediate with an unsaturated cpoxide-functional compound.

10. The method of claim 7, wherein the unsaturated e pox i d c- f u nc t i o n a I compound is selected from the group consisting of glycidyl mcthacrylatc, glycidyl acrylate, oleyl glycidyl ether and combinations thereof.

1 1. The method of claim 7, wherein (b) comprises reacting the first extended intermediate with a ful ly saturated cpoxide-functional compound to provide a second extended intermediate comprising reactive hydroxyl groups, and reacting the second extended intermediate comprising reactive hydroxyI groups with an unsaturated anhydride to form the hyperbranehed star polymer.

12. The method of claim 1 1 , wherein the fully saturated cpo.xidc-functional compound is selected from the group consisting of glycidyl neodecanoate, glycidyl ncononanoate and combinations thereof.

13. The method of claim 1 1 , wherein the unsaturated anhydride is selected from the group consisting of maleic anhydride, dimethylmaleic anhydride, dodccenylsuccinic anhydride. 2-octen-ylsuccinic anhydride, oleic anhydride, erucic anhydride and combinations thereof

14. The method of claim 1 , w herein the method provides a hyperbranehed star polymer containing a branch point with multiple chains.

1 5. A method of producing a coating on a substrate surface, the method comprising:

(a) applying a coating composition comprising:

i. the hyperbranehed star polymer made by the method of claim I ; and

ii. a photoinitiator

to a substrate surface;

(b) curing the polymer in situ by free radical polymerization.

16. The method of claim 15, w herein curing comprises actinic radiation.

1 7. The method of claim 1 5, w herein the photoinitiator is selected from the group consisting of diaryl ketone derivatives, benzoin alkyl ethers, alkoxy phenyl ketones, 0- acyiated oximinoketones, polycyclic quinones, benzophenones and substituted benzophenones, xanthones, thioxanthones, chlorosulfonyl and chloromethyl polynucl ear aromatic compounds, chlorosulfonyl and chloromethyl heterocyclic compounds, chlorosulfonyl and chloromethyl benzophenones and fluorenones, haloalkanes and combinations thereof.

A coating produced by the method of claim 15.

A method of producing a coating on a substrate surface, the method comprising:

(a) applying a coating composition comprising

i. the hyperbranched star polymer made by the method of claim 7; and

ii. a photoinitiator

to a substrate surface;

(b) curing the polymer in situ by free radical polymerization.

20. The method of claim 1 9, wherein curing comprises actinic radiation.

21. The method of claim 19, wherein the photoinit iator is selected from the group consisting of diaryl ketone derivatives, benzoin alkyl ethers, alkoxy phenyl ketones, 0- acylated oximinoketones, polycyclic quinones, benzophenones and substituted benzophenones, xanthones, thioxanthones, chlorosulfonyl and chloromethyl polynucl ear aromatic compounds, chlorosulfonyl and chloromethyl heterocyclic compounds, chlorosulfonyl and chloromethyl benzophenones and fluorenones, haloalkanes and combinations thereof.

A coating produced by the method of claim 19.

A method of making a hyperbranched star polymer, the method comprising

(a) reacting trimethyiolpropane with hexahydrophthalic anhydride to provide a first extended intermediate;

(b) reacting the first extended intermediate with giycidyl neodecanoate to provide a second extended intermediate; and (c) reacting the second extended intermediate with dodeccnylsuccinic anhydride to form the hyperbranched star polymer.