MXPA01001960A

MXPA01001960A - Thermosetting compositions containing hydroxyl-functional polymers prepared using atom transfer radical polymerization

Info

Publication number: MXPA01001960A
Application number: MXPA/A/2001/001960A
Authority: MX
Inventors: Dwyer James B O; Daniela White; Dennis A Simpson
Original assignee: Ppg Industries Ohio Inc
Priority date: 1998-08-31
Filing date: 2001-02-23
Publication date: 2001-12-04

Abstract

A thermosetting composition is provided comprising:(a) a crosslinking agent having at least two functional groups that are reactive with hydroxyl groups;and (b) a non-gelled, hydroxyl functional polymer prepared by atom transfer radical polymerization, in the presence of an initiator having at least one radically transferable group. The polymer contains at least one of the following polymer chain structures:-{(M)p-(G)q}x- or -{(G)q-(M)p}x- wherein M is a residue, that is free of hydroxyl functionality, of at least one ethylenically unsaturated radically polymerizable monomer;G is a residue, that has hydroxyl functionality, of at least one ethylenically unsaturated radically polymerizable monomer;p and q represent average numbers of residues occuring in a block of residues in each polymer chain structure;and p, q, and x are each independently selected for each structure such that the hydroxyl functional polymer has a number average molecular weight of at least 250. Also provided by the present invention are methods of coating a substrate using compositions of the present invention and substrates coated by such methods, as well as color-plus-clear composite coatings.

Description

THERMO-DENSITIVE COMPOSITIONS CONTAINING POLYMERS WITH HYDROXYL FUNCTIONALITY PREPARED USING THE POLYMERIZATION OF RADICALS BY TRANSFER OF ATOMS FIELD OF THE INVENTION The present invention relates to thermosettable (curable) compositions of one or more polymers with hydroxyl functionality. The hydroxyl functional polymer is prepared by radical polymerization by atom transfer, and has a well defined polymer chain structure, molecular weight and molecular weight distribution. The present invention also relates to methods for coating substrates, to substrates coated by such methods, and to composite light-layer-plus-clear coating compositions.

BACKGROUND OF THE INVENTION In recent years, the reduction of the environmental impact of curable compositions, such as that associated with air emissions of volatile organic compounds during the application of curable coating compositions, has been an area of research and development. continuous Accordingly, the interest in liquid coating compositions with high solids content has been increasing, due in part to their comparatively lower organic volatile content (VOC), which significantly reduces air emissions during the process of application. Lower VOC coating compositions are particularly desirable in the original automotive equipment manufacturing (OEM) market, due to the relatively large volume of coatings that are used. However, in addition to the requirement for low VOC levels, automobile manufacturers have very strict operating requirements for the coatings that are used. For example, it is typically required that automotive OEM top coatings have a combination of good exterior durability and excellent gloss and appearance. Thermosetting coatings containing hydroxyl functional polymers have been used extensively as OEM primers and topcoats for automobiles. Such coating compositions typically comprise a crosslinking agent having at least two functional groups that are reactive with hydroxyl groups, and a hydroxyl functional polymer. The hydroxyl functional polymers used in such coating compositions are typically prepared by standardized, ie non-active, radical polymerization methods, which provide little control over the molecular weight, molecular weight distribution and structure of the polymer chain. The physical properties, e.g., the viscosity, of a given polymer can be directly related to its molecular weight. The higher molecular weights are typically associated, for example, with values of Tg and higher viscosities. The physical properties of a polymer having a broad molecular weight distribution, eg, having a polydispersity index (PDI) of more than 2.5, can be characterized as an average of the individual physical properties and the indeterminate interactions between the different polymer species that comprise it. As such, the physical properties of polymers having broad molecular weight distributions can be variable and difficult to control. The structure of the polymer chain, or architecture, of a polymer can be described as the sequence of monomeric moieties along the backbone or backbone of the polymer. A hydroxyl functional copolymer prepared by standardized radical polymerization techniques will contain a mixture of polymeric molecules with individual hydroxyl equivalent weights and variable polymer chain structures. In such a copolymer, functional hydroxyl groups are located randomly along the polymer chain. On the other hand, the number of functional groups is not equally divided among the polymeric molecules, so that some polymeric molecules can actually be free of hydroxyl functionality. In a thermosetting composition, the formation of a three-dimensional crosslinked network depends on the functional equivalent weight as well as the architecture of the individual polymeric molecules comprising it. Polymeric molecules that have little or no reactive functionality (or have functional groups that are unlikely to participate in cross-linking reactions due to their locations along the polymer chain) will contribute little or nothing to the formation of the three-dimensional crosslinked network , producing a decrease in the crosslinking density and physical properties below the optimum of the finally formed polymerized product, eg, a cured or thermoset coating.

The continuous development of new and improved thermosetting compositions with lower VOC levels and a combination of favorable performance properties is desirable. In particular, it would be desirable to develop thermosetting compositions comprising hydroxyl-functional copolymers with well-defined molecular weights and polymer chain structures, and narrow molecular weight distributions, e.g., PDI values less than 2.5. In the publication of the international patent WO 97/18247 and US Patents 5,763,548 and 5,789,487 a radical polymerization process referred to as radical polymerization by atom transfer (ATRP) is described. The ATRP process is described as an active radical polymerization that produces the formation of polymers with a predictable molecular weight and molecular weight distribution. It is also disclosed that the ATRP procedure of these publications provides very uniform products having a controlled structure (ie topology, controllable composition, etc.). These patents also disclose polymers prepared by ATRP, which are useful in a wide variety of applications, for example, with paints and coatings. It would be desirable to develop thermosetting compositions comprising hydroxyl functional copolymers prepared using radical polymerization by atom transfer, thereby having well-defined molecular weights and chain structures, and narrow molecular weight distributions.

Such compositions would have lower VOC levels due to lower viscosities, and a combination of favorable operating properties, particularly in coatings applications. COMPENDIUM OF THE INVENTION According to the present invention, there is provided a thermosetting composition comprising: (a) a crosslinking agent having at least two functional groups that are reactive with hydroxyl groups; and (b) a hydroxyl-functional, non-gelled polymer prepared by radical polymerization by atom transfer, in the presence of an initiator having at least one group capable of radical transfer, and wherein the polymer contains at least one of the following structures of the polymer chain: -. { (M) p- (G) q} ? - or - { (G) q- (M) P} X-wherein M is a residue, lacking hydroxyl functionality, of at least one monomer susceptible to ethylenically unsaturated radical polymerization; G is a residue, having hydroxyl functionality, of at least one monomer capable of ethylenically unsaturated radical polymerization; p and q represent the average number of remains that appear in a block of debris in each structure of the polymer chain; and p, q, and x are each independently selected for each structure so that the hydroxyl functional polymer has a number average molecular weight of at least 250. Methods of coating a substrate using the compositions of the invention are also provided by the present invention. the present invention, the substrates coated by such methods, and the clear color-plus-layer coating compositions composed. It should be understood that all numbers other than those used in the operation examples, or where otherwise indicated, which express amounts of ingredients, reaction conditions, etc. of the specification and the claims are modified in all cases by the term "approximately". DETAILED DESCRIPTION Used herein, the term "polymer" is intended to refer to both homopolymers, ie, polymers formed by a single species of monomer, such as copolymers, ie, polymers formed by two or more species of monomers, as well as oligomers. The hydroxyl functional polymer used in the composition of the present invention is an ungelled polymer prepared by radical polymerization by atom transfer, in the presence of an initiator having at least one group capable of radical transfer. The polymer contains at least one of the following structures of the polymer chain: or (II) -. { (G) g- (M) P} X-where M is a residue, which lacks hydroxyl functionality, of at least one monomer susceptible to ethylenically unsaturated radical polymerization; G is a residue, having hydroxyl functionality, of at least one monomer capable of ethylenically unsaturated radical polymerization; p and q represent the average number of remains that appear in a block of debris in each structure of the polymer chain; and p, q, and x are each independently selected for each structure so that the hydroxyl functional polymer has a number average molecular weight (Mn) of at least 250, preferably at least 1,000, and more preferably at least 2,000. The hydroxyl functional polymer also typically has an Mn of less than 16,000, preferably less than 10,000, and more preferably less than 5,000. The Mn of the hydroxyl functional polymer can range between any combination of these values, including the values quoted. Unless otherwise indicated, all molecular weights described in the specification and claims are determined by gel permeation chromatography using a polystyrene standard. Note that structures I and II define "x segments" within the polymer. The subscripts p and q shown in structures I and II represent the average numbers of residues that appear in a block of remains of each structure of the polymer chain. Typically, p and q each independently have a value of 0 or more, preferably at least 1, and more preferably at least 5 for each of the general polymeric structures I and II. Also, typically the subscripts p and q each independently have a value of less than 100, preferably less than 20, and more preferably less than 15 for each of the general polymeric structures I and II. The values of the subscripts p and q may vary between any combination of these values, including the values quoted. On the other hand, the sum of p and q is greater than zero within a segment x and q is greater than zero at least within a segment x of the polymer.

Typically, the subscript x shown in structures I and II has a value of at least 1. Also, the subscript x typically has a value of less than 100, preferably less than 50, and more preferably less than 10. The value of the subscript x can oscillate between any combination of these values, including the values quoted. On the other hand, when there is more than one of the structures I and / or II in the polymer molecule, x can have different values for each structure (as can p and q) allowing a variety of polymeric architectures, such as gradient copolymers. The - (M) p- portion of the general structures I and II represents (1) a homoblock of a single type of M residue (having p units of length), (2) an alternating block of two types of M residues, (3) a polyblock of two or more types of M residues, or (4) a gradient block of two or more types of M moieties. For illustrative purposes, when preparing the block M from, for example, 10 moles of methyl methacrylate, the - (M) p- portion of structures I and II represents a homoblock of 10 methyl methacrylate residues. In the case where the M block is prepared, for example, from 5 moles of methyl methacrylate and 5 moles of butyl methacrylate, the - (M) p- portion of the general structures I and II typically represents, depending of the preparation conditions, as is known to one of ordinary skill in the art: (a) a diblock of 5 methyl methacrylate residues and 5 butyl methacrylate residues having a total of 10 residues (ie, p = 10); (b) a diblock of 5 residues of butyl methacrylate and 5 residues of methyl methacrylate having a total of 10 residues; (c) an alternating block of residues of methyl methacrylate and butyl methacrylate starting either in a methyl methacrylate residue or in a butyl methacrylate residue, and having a total of 10 residues; or (d) a gradient block of residues of methyl methacrylate and butyl methacrylate starting either with methyl methacrylate residues or with butyl methacrylate residues having a total of 10 residues. The portions - (G) q- of the structures of the polymer chain I and II can be described in a manner similar to that of the - (M) p- portions. The following is presented in order to illustrate the different polymeric architectures that are represented by the structures of the polymer chain I and II.

Polymer architecture of homoblocks: When x is 1, p is 0 and q is 5, the structure of the general polymer chain I represents a homoblock of 5 residues G, as more specifically represented by the following general formula III. III - (G) - (G) - (G) - (G) - (G) - Architecture of the diblock copolymer: When x is 1, p is 5 and q is 5, the structure of the general polymer chain I represents a diblock of 5 M residues and 5 G residues as represented more specifically by the following general formula IV. IV - (M) - (M) - (M) - (M) - (M) - (G) - (G) - (G) - (G) - (G) - Architecture of the alternating copolymer: When x is greater than 1, for example 5, and p and q are each 1 for each segment x, the structure of the polymer chain I represents an alternating block of residues M and G, as more specifically represented by the following general formula V. V - ( M) - (G) - (M) - (G) - (M) - (G) - (M) - (G) - (M) - (G) -Architecture of the gradient copolymer: When x is greater than 1, for example, 4, ypyq are each independently within the range, for example, from 1 to 3, for each segment x, the structure of the polymer chain I represents a block in gradient of residues M and G, as shown more specifically by the following general formula VI. VI - (M) - (M) - (M) - (G) - (M) - (M) - (G) - (G) - (M) - (G) - (G) - (M) - (G) - (G) - (G) - Gradient copolymers can be prepared from two or more monomers by ATRP methods, and are generally described as having an architecture that changes gradually and in a systematic and predictable manner throughout of the polymer backbone. The gradient copolymers can be prepared by ATRP methods (a) by varying the proportion of monomers introduced into the reaction medium during the course of the polymerization, (b) by using a feed monomer containing monomers with different polymerization rates, or ( c) a combination of (a) and (b). The gradient copolymers are described in more detail on pages 72 to 78 of the international patent publication WO 97/18247. The remainder M of the structures of the general polymer chain I and II derives at least one monomer capable of ethylenically unsaturated radical polymerization. Used herein and in the claims it is intended that "monomer susceptible to ethylenically unsaturated radical polymerization" and similar terms include vinyl monomers, (meth) allyl monomers, olefins and other ethylenically unsaturated monomers that are susceptible to radical polymerization. The classes of vinyl monomers from which M can be derived include, but are not limited to, (meth) acrylates, vinyl aromatic monomers, vinyl halides and vinyl esters of carboxylic acids. Used herein and in the claims "(meth) acrylate" and similar terms mean both methacrylates and acrylates. Preferably, the moiety M is derived from at least one alkyl (meth) acrylate having from 1 to 20 carbon atoms in the alkyl group, vinyl aromatic monomers, vinyl halides, vinyl esters of carboxylic acids and olefins. Specific examples of the alkyl (meth) acrylates having from 1 to 20 carbon atoms in the alkyl group from which the M moiety can be derived include, but are not limited to, methyl (meth) acrylate, ( met) ethyl acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, t-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) acrylate lauryl, isobornyl (meth) acrylate, cyclohexyl (meth) acrylate, 3,3,5-trimethylcyclohexyl (meth) acrylate, and isobutyl (meth) acrylate. The moiety M can also be selected from monomers having more than one (meth) acrylate group, for example, (meth) acrylic anhydride and bis ((meth) acrylate) of diethylene glycol. The moiety M can also be selected from among alkyl (meth) acrylates containing groups capable of radical transfer, which can act as branching monomers, for example 2- (2-bromopropionoxy) ethyl acrylate. Specific examples of the vinyl aromatic monomers from which M can be derived include, but are not limited to, styrene, p-chloromethylstyrene, divinylbenzene, vinylnaphthalene and divinylnaphthalene. The vinyl halides from which M can be derived include, but are not limited to, vinyl chloride and vinylidene fluoride. The vinyl esters of carboxylic acids from which M can be derived include, but are not limited to, vinyl acetate, vinyl butyrate, vinyl benzoate, vinyl esters of VERSATIC Acid (VERSATIC Acid is a mixture of carboxylic acids tertiary aliphatics available from Shell Chemical Company), and the like. Used herein and in the claims, "olefin" and similar terms mean unsaturated aliphatic hydrocarbons having one or more double bonds, obtained by petroleum cracking fractions. Specific examples of the olefins from which M can be derived include, but are not limited to, propylene, 1-butene, 1,3-butadiene, isobutylene and di-isobutylene. As used herein and in the claims, "(meth) allylic monomer or monomers" means monomers containing substituted and / or unsubstituted allylic functionality, that is, one or more radicals represented by the following general formula VII, VII H2C = C (R ) -CH2- where R is hydrogen, halogen or a Cx to C alkyl group. Most commonly, R is hydrogen or a methyl group. Examples of the (meth) allylic monomers include, but are not limited to: (meth) allyl alcohol; (meth) allyl ethers, such as methyl (meth) allyl ether; esters (meth) allylic acids of carboxylic acids, such as acetate (meth) allyl; benzoate of (meth) allyl; n-butyrate of (meth) allyl; (Meth) allyl esters of VERSATIC Acid; and similar. Other monomers susceptible to polymerization of ethylenically unsaturated radicals from which M can be derived include, but are not limited to: cyclic anhydrides, e.g., maleic anhydride, 1-cyclopentene-1,2-dicarboxylic anhydride and itaconic anhydride; esters of acids that are unsaturated but do not have α, β-ethylenic unsaturation, e.g., undecylenic acid methyl ester; and diesters of ethylenically unsaturated dibasic acids, e.g., diethyl maleate. The designated monomeric block (G) g of the above structures may be derived from a type of monomer or from a mixture of two or more monomers. As discussed above, such mixtures can be blocks of monomeric moieties or they can be alternating moieties. The remainder G of the structures of the general polymer chains I and II may be derived from monomers having hydroxyl functionality. Typically the residue G is derived from at least one of the hydroxyalkyl acrylates and hydroxyalkyl methacrylates having from 2 to 4 carbon atoms in the hydroxyalkyl group, including, for example, hydroxyethyl (meth) acrylate, hydroxypropyl (meth) acrylate. , hydroxybutyl (meth) acrylate, and the like. The residue G can alternatively be derived from allylic alcohols and vinyl alcohols. Alternatively, the hydroxyl functionality can be incorporated into the polymer by post-reaction, for example by first preparing an epoxy or acid functional polymer and reacting it with a compound having an acid function (if the polymer has epoxy functionality) or with an epoxy function ( if the polymer has acid functionality) to form a polymer having a secondary hydroxyl functionality. Preferably, the polymer contains at least one of the following structures in the polymer chain: (VIII) f- [. { (M) p- (G) q} x- (M) r-T] z or (IX) f- [. { (G) q- (M) P} X- (G) ST] z where the subscripts r and s represent the average number of residues that appear in the respective blocks of residues M and G. The portions - (M) r- and - (G) a- of the general structures VIII and IX have meanings similar to those previously described here with respect to the portions - (M) p- and - (G) q-. The radical f is or is derived from a residue of the free initiator of the group capable of radical transfer; p, q, and x are defined as before; z is at least 1; T is or is derived from the group susceptible to radical transfer of the initiator; and the epoxy functional polymer has a polydispersity index of less than 2.5, preferably less than 2.0, more preferably less than 1.8, and even more preferably less than 1.5. It should be understood that structures VIII and IX may represent the polymer itself or, alternatively, each of the structures may comprise a terminal segment of the polymer. For example, when the polymer is prepared by ATRP using an initiator having a group capable of radical transfer and z is 1, any of the structures VIII and IX can represent a complete linear polymer. However, when the hydroxyl functional polymer is a star polymer or other branched polymer, where some of the branches may not have hydroxyl functionality, the structures of the general polymer chain VIII and IX represent a portion of the polymer with hydroxyl functionality.

For each of the general polymer structures VIII and IX, the subscripts r and s independently have a value of 0 or more. The subscripts r and s each independently independently have a value of less than 100, preferably less than 50, and more preferably less than 10, for each of the general polymer structures VIII and IX. Each of the values of r and s can range between any combination of these values, including the values quoted. The hydroxyl functional polymer typically has a hydroxyl equivalent weight of at least 116 grams / equivalent, preferably at least 200 grams / equivalent. The hydroxyl equivalent weight of the polymer is also preferably less than 10,000 grams / equivalent, preferably less than 5,000 grams / equivalent, and more preferably less than 1,000 grams / equivalent. The hydroxyl equivalent weight of the hydroxyl functional polymer can range between any combination of these values, including the values quoted. The equivalent weights in hydroxyl functionality, used herein, are determined in accordance with ASTM E 222-94. As mentioned above, the hydroxyl functional polymer used in the thermosetting compositions of the present invention is prepared by radical polymerization by atom transfer. The ATRP method is described as an "active polymerization", that is, a chain growth polymerization that propagates essentially without chain transfer and essentially without chain termination. The molecular weight of a polymer prepared by ATRP can be controlled by the stoichiometry of the reactants, i.e. the initial concentration of monomer or monomers and of initiator or initiators. In addition, ATRP also provides polymers having characteristics including, for example, narrow molecular weight distributions, eg, PDI values of less than 2.5, and a well-defined polymer chain structure, eg, block copolymers and polymers alternating It can generally be described that the ATRP process comprises: polymerizing one or more monomers susceptible to radical polymerization in the presence of an initiation system; form a polymer; and isolating the formed polymer. The initiation system comprises: an initiator having at least one atom or group capable of radical transfer; a transition metal compound, i.e., a catalyst, participating in a reversible redox cycle with the initiator; and a ligand, which coordinates with the transition metal compound. The ATRP process is described in greater detail in international patent publication WO 97/18247 and in U.S. Patent Nos. 5,763,548 and 5,789,487. In preparing the hydroxyl-functional polymers of the present invention, the initiator can be selected from the group consisting of linear or branched aliphatic compounds, cycloaliphatic compounds, aromatic compounds, polycyclic aromatic compounds, heterocyclic compounds, sulfonyl compounds, sulfenyl compounds, carboxylic acid esters , polymeric compounds, and mixtures thereof, each having at least one group capable of radical transfer, which is typically a halo group. The initiator may also be substituted with functional groups, e.g., hydroxyl groups. Additional useful initiators and the different groups susceptible to transfer of radicals that can be associated with them are described on pages 42 to 45 of the international patent publication WO 97/18247. Polymeric compounds (including oligomeric compounds) having groups capable of radical transfer can be used as initiators, and are referred to herein as "macroinitiators". Examples of the macroinitiators include, but are not limited to, polystyrene prepared by cationic polymerization and having a terminal halide eg, chloride, and a polymer of 2- (2-bromopropionoxy) ethyl acrylate and one or more (meth ) alkyl acrylates, eg, butyl acrylate, prepared by conventional non-active radical polymerization. Macroinitiators can be used in the ATRP process to prepare graft polymers, such as grafted block copolymers and comb copolymers. An additional discussion on macroinitiators is found in U.S. Patent No. 5,789,487.

Preferably, the initiator may be selected from the group consisting of halomethane, methylene halide, haloform, carbon tetrahalide, methanesulfonyl halide, p-toluenesulfonyl halide, methanesulfenyl halide, p-toluenesulfenyl halide, l-phenylethyl halide, halohanedionitrile, C 1 -C 6 -alkyl ester of 2-halocarboxylic acid C x -Cg, p-halomethylstyrene, mono-hexa is (octhalo-C 1 -C 6 alkyl) benzene, diethyl-2-halo-2-methyl malonate, halide of benzyl, ethyl 2-bromoisobutyrate and mixtures thereof. A particularly preferred initiator is diethyl-2-bromo-2-methyl malonate. Among the catalysts that can be used in the preparation of hydroxyl functional polymers of the present invention, any transition metal compound that can participate in a redox cycle with the initiator and the growing polymer chain is included. It is preferred that the transition metal compound does not form direct carbon-metal bonds with the polymer chain. The transition metal catalysts useful in the present invention may be represented by the following general formula X X TMn + Qn where TM is the transition metal, n is the formal charge of the transition metal having a value of 0 to 7, and Q is a counterion or a covalently bonded component. Examples of the transition metal (TM) include, but are not limited to, Cu, Au, Ag, Hg, Pd, Pt, Co, Mn, Ru, Mo, Nb, Fe, and Zn. Examples of Q include, but are not limited to, halogen, hydroxy, oxygen, C6-C6 alkoxy, cyano, cyanate, thiocyanate and azido. A preferred transition metal is Cu (I) and Q is preferably halogen, e.g., chloride. Accordingly, a preferred class of transition metal catalysts are copper halides, e.g., Cu (I) Cl. It is also preferred that the transition metal catalyst contains a small amount, e.g., 1 mole percent, of a redox conjugate, for example, Cu (II) Cl2 when Cu (I) Cl is used. Additional catalysts useful in the preparation of hydroxyl functional polymers of the present invention are described on pages 45 and 46 of the international patent publication WO 97/18247. The redox conjugates are described on pages 27 to 33 of the publication of the international patent WO 97/18247.

Ligands that can be used in the preparation of hydroxyl-functional polymers of the present invention include, but are not limited to, compounds that have one or more nitrogen, oxygen, phosphorus and / or sulfur atoms, which can be coordinated with the transition metal catalyst compound, eg , through sigma and / or pi links. The classes of useful ligands include, but are not limited to: unsubstituted and substituted pyridines and bipyridines; porphyrins; cryptandos; crown ethers; e.g., 18-crown-6; polyamines, e.g., ethylenediamine; glycols, e.g., alkylene glycols, such as ethylene glycol; carbon monoxide; and coordinating monomers, e.g., styrene, acrylonitrile and hydroxyalkyl (meth) acrylates. A preferred class of ligands are the substituted bipyridines, e.g., 4,4'-dialkyl-bipyridyls. Additional ligands that can be used in the preparation of the epoxy functional polymers of the present invention are described on pages 46 to 53 of the international patent publication WO 97/18247. In the preparation of the hydroxyl functional polymers of the present invention the amounts and relative proportions of the initiator, the transition metal compound and the ligand are those for which the ATRP functions more efficiently. The amount of initiator used can vary widely and is typically present in the reaction medium at a concentration of 10 ~ 4 moles / liter (M) to 3 M, for example, 10"3 M to 10" 1 M. As the Molecular weight of the hydroxyl functional polymer can be directly related to the relative concentrations of initiator and of monomer or monomers, the molar ratio of initiator to monomer is an important factor in the polymer preparation. The mole ratio of initiator to monomer is typically within the range of 10 ~ 4: 1 to 0.5: 1, eg, 10"3: 1 to 5 x "1.

In the preparation of the hydroxyl functional polymers of the present invention, the molar ratio of the transition metal compound to the initiator is typically in the range of 10 ~ 4: 1 to 10: 1, e.g., 0.1: 1 at 5: 1. The molar ratio of the ligand to the transition metal compound is typically in the range of 0.1: 1 to 100: 1, for example, 0.2: 10: 1. Polymers with hydroxyl functionality useful in the thermosetting compositions of the present invention may be prepared in the absence of solvent, i.e., by means of a bulk polymerization process. Generally, the hydroxyl functional polymer is prepared in the presence of a solvent, typically water and / or an organic solvent. Useful classes of organic solvents include, but are not limited to, ethers, cyclic ethers, C5-C10 alkanes C5-C10 cycloalkanes, aromatic hydrocarbon solvents, halogenated hydrocarbon solvents, amides, nitriles, sulfoxides, sulfones and mixtures thereof . Supercritical solvents, such as C02, C? -C4 alkanes and fluorocarbons can also be used. A preferred class of solvents are aromatics, of which particularly preferred are xylene and SOLVESSO 100, a combination of aromatic solvents available from Exxon Chemicals America. The additional solvents are described in greater detail on pages 53 to 56 of the publication of the international patent WO 97/18247. The hydroxyl functional polymer is typically prepared at a reaction temperature in the range of 25 ° C to 140 ° C, preferably 50 ° C to 100 ° C, and at a pressure in the range of 1 to 100 atmospheres, typically at ambient pressure Radical polymerization by atom transfer is typically completed in less than 24 hours, e.g., between 1 and 8 hours. Prior to use in the thermosetting compositions of the present invention, the transition metal catalyst of ATRP and its associated ligand are typically separated or removed from the hydroxyl functional polymer. This, however, does not constitute a requirement of the invention. Removal of the ATRP catalyst is accomplished using known methods, including, for example, adding a catalyst binding agent to the polymer mixture, the solvent and the catalyst, followed by filtration. Examples of suitable catalyst binding agents include, for example, alumina, silica, clay or a combination thereof. A mixture of the polymer, the solvent and the ATRP catalyst can be passed through a bed of a catalyst binding agent. Alternatively, the ATRP catalyst can be oxidized in situ and retained in the hydroxyl functional polymer. The hydroxyl functional polymer can be selected from the group consisting of linear polymers, branched polymers, hyper-xamified polymers, star polymers, graft polymers and mixtures thereof. The shape, or coarse architecture, of the polymer can be controlled by choosing the initiator and the monomers used in its preparation. Linear hydroxyl functional polymers can be prepared using initiators having one or two groups capable of radical transfer, e.g., diethyl-2-halo-2-methyl malonate and a, a'-dichloroxylene. The branched hydroxyl functional polymers can be prepared using branching monomers, ie, monomers containing groups capable of radical transfer or more than one group capable of ethylenically unsaturated radical polymerization, eg, 2- (2-bromopropionoxy) acrylate. ethyl, p-chloromethylstyrene and bis- (methacrylate) of diethylene glycol. The hyper-branched hydroxyl functional polymers can be prepared by increasing the amount of branching monomer used. Polymers with star hydroxyl functionality can be prepared using initiators that have three or more groups capable of radical transfer, e.g., hexakis (bromomethyl) benzene. As is known to those of ordinary skill in the art, star polymers can be prepared by core-arm or arm-core methods. In the core-arm method, the star polymer is prepared by polymerizing monomers in the presence of the polyfunctional initiator, e.g., hexakis (bromomethyl) benzene. Polymeric chains or arms, of similar composition and architecture, are developed from the nucleus initiator, in the core-arm method. In the arm-core method, the arms are prepared separately from the core and can optionally have different compositions, architecture, molecular weight and PDI. The arms can have different hydroxyl equivalent weights, and some can be prepared without any hydroxyl functionality. After the preparation of the arms, they are anchored to the core.

Hydroxyl functional polymers in the form of graft polymers can be prepared using a macroinitiator, as previously described herein. The graft, branched, hyper-branched and star polymers are described in more detail on pages 79 to 91 of the international patent publication WO 97/18247. The polydispersity index (PDI) of the hydroxyl functional polymers useful in the present invention is typically less than 2.5, more typically less than 2.0, and preferably less than 1.8, eg, 1.5. Used herein, and in the claims, the "polydispersity index" is determined from the following equation: (weight average molecular weight (Mw) / number average molecular weight (Mn)). A monodisperse polymer has a PDI of 1.0. The symbol f shown in structures VIII and IX is or is derived from a residue of the free initiator of the group susceptible to radical transfer; very often it is a sulphonyl group or a malonate. For example, if the hydroxyl functional polymer is initiated by a benzyl bromide, f, or more specifically, f-, is a moiety with the structure: Also, f, can be derived from a remainder of the initiator. For example, when the polymer is initiated using epichlorohydrin, f, or more specifically, f-, is the 2,3-epoxy-propyl moiety, The 2,3-epoxy-propyl moiety can then be converted, for example, to a 2,3-dihydroxypropyl moiety. Derivatives or conversions of the initiator moiety are preferably performed at a point in the ATRP process in which the loss of hydroxyl functionality along the polymer backbone is minimal, for example, before incorporating a block of moieties having hydroxyl functionality . In general formulas VIII and IX, the subscript z is equal to the number of polymer chains with hydroxyl functionality that are anchored to f. The subscript z is at least 1 and can have a wide range of values. In the case of comb or graft polymers, where f is a macroinitiator having numerous groups capable of transferring pending radicals, z can have a value of more than 10, for example, 50, 100 or 1,000. Typically, z is less than 10, preferably less than 6, and most preferably less than 5. In a preferred embodiment of the present invention, z is 1 or 2. The symbol T of the general formulas VIII and IX is or is derived from the susceptible group. of radical transfer of the initiator. For example, when the hydroxyl functional polymer is prepared in the presence of diethyl-2-bromo-2-methyl malonate, T may be the bromine group susceptible to radical transfer. The group susceptible to radical transfer may be optionally (a) removed or (b) chemically converted to another radical. In either (a) or (b), it is considered that the symbol T here derives from the group susceptible to radical transfer of the initiator. The group susceptible to radical transfer can be removed by substitution with a nucleophilic compound, e.g., an alkali metal alkoxylate. In the present invention, it is desirable that the method by which the group susceptible to radical transfer is chemically removed or converted is also relatively smooth with respect to the hydroxyl functionality of the polymer. In a preferred embodiment of the present invention, the group susceptible to radical transfer is a halogen and is removed by means of a mild dehalogenation reaction, which does not reduce the hydroxyl functionality of the polymer. The reaction is typically performed as a post-reaction once the polymer has been formed, and in the presence of at least one catalyst for ATRP. Preferably, the post-halogenation reaction is carried out in the presence of both a catalyst for ATRP and its associated ligand. The mild de-halogenation reaction is carried out by contacting the halogen-terminated hydroxyl-functional polymer of the present invention with one or more ethylenically unsaturated compounds, which are not readily susceptible to radical polymerization within at least a portion of the spectrum of conditions in which radical polymerizations are carried out by atom transfer, hereinafter referred to as "ethylenically unsaturated compounds susceptible to limited radical polymerization" (compound LRPEU).

Used herein, it is intended that "halogen-terminated" and similar terms also include the pendant halogens, e.g., those that would be present in the branched, comb and star polymers. Not wishing to be bound by any theory, it is believed, based on the evidence at hand, that the reaction between the halogen-terminated hydroxyl functional polymer and one or more LRPEU compounds produces (1) the elimination of the terminal halogen group, and (2) ) the addition of at least one carbon-carbon double bond where the terminal carbon-halogen bond breaks. The de-halogenation reaction is typically carried out at a temperature in the range of 0 ° C to 200 ° C, eg, 0 ° C to 160 ° C, at a pressure in the range of 0.1 to 100 atmospheres , eg, from 0.1 to 50 atmospheres. The reaction is also typically performed in less than 24 hours, e.g., between 1 and 8 hours. Although the LRPEU compound can be added in a smaller amount than the stoichiometric, it is preferably added in a stoichiometric amount at least in relation to the moles of terminal halogen present in the hydroxyl-functional polymer. When added in an amount greater than stoichiometric, the compound LRPEU is typically present in an amount not greater than 5 mole%, e.g. , from 1 to 3% in moles, above the total moles of terminal halogen. Among the ethylenically unsaturated compounds susceptible to limited radical polymerization useful for dehalogenating the hydroxyl functional polymer of the composition of the present invention under mild conditions are those represented by the following general formula XII. XII R3 Ri R3 R2 In general formula XII, Ri and R2 can be identical or different organic groups such as: alkyl groups having from 1 to 4 carbon atoms; aryl groups; alkoxy groups; ester groups; alkyl sulfur groups; acyloxy groups; and alkyl groups containing nitrogen wherein at least one of the groups Ri and R2 is an organogroup while the other may be an organogroup or a hydrogen. For example, when one of Ri or R2 is an alkyl group, the other may be an alkyl, aryl, acyloxy, alkoxy, arene, sulfur-containing alkyl group, or nitrogen-containing alkyl and / or nitrogen-containing aryl groups. The R3 groups can be the same or different groups selected from hydrogen or lower alkyl selected such that the reaction between the terminal halogen of the hydroxyl functional polymer and the LRPEU compound is not impeded. Likewise, a group R3 can be attached to the groups Ri and / or R2 to form a cyclic compound. It is preferred that the compound LRPEU be free of halogen groups. Examples of suitable LRPEU compounds include, but are not limited to, 1,1-dimethylethylene, 1,1-diphenylethylene, isopropenyl acetate, alpha-methylstyrene, 1,1-dialkoxyolefin, and mixtures thereof. Additional examples include dimethyl itaconate and diisobutene (2,4,4-trimethyl-1-pentene). For purposes of illustration, the reaction between the halogen-terminated hydroxyl functional polymer and the LRPEU compound, e.g., alpha-methylstyrene, is summarized in the following general scheme 1. General Scheme 1 P-X + H2C + HX In general scheme 1, P-X represents the hydroxyl-functional polymer terminated in halogen. As indicated above, the hydroxyl functional polymer can have any of a portion of polymeric structures, selected from linear polymers, branched polymers, hyper-branched polymers, star polymers, gradient polymers, and graft polymers. Mixtures of one or more different types of these polymers can be used in the composition of the present invention. The hydroxyl functional polymer can be used in the thermosetting composition of the present invention as a resinous binder or as a combined additive with a separate resinous binder., which can be prepared by radical polymerization methods by conventional atomization or polymerization. When used as an additive, the hydroxyl functional polymer described above may have a low functionality (may be monofunctional) and also a high equivalent weight. Alternatively, for other applications such as use as a reactive diluent, the additive can be highly functional with an equally low equivalent weight.

The hydroxyl functional polymer is typically present in the thermosetting composition of the present invention in an amount of at least 0.5 percent by weight (when used as an additive), preferably at least 10 percent by weight (when it is used as a resinous binder), and more preferably at least 25 weight percent, based on the total weight of resin solids of the thermosetting composition. The thermosetting composition also typically contains hydroxyl functional polymer present in an amount of less than 99.5 weight percent, preferably less than 90 weight percent, and more preferably less than 75 weight percent, based on the total weight of resin solids of the thermosetting composition. The hydroxyl functional polymer may be present in the thermosetting composition of the present invention in an amount ranging from any combination of these values, including the values quoted. The thermosetting composition of the present invention additionally comprises a crosslinking agent having at least two functional groups that are reactive with hydroxyl groups. Examples of suitable crosslinking agents include aminoplasts containing methylol and / or methylol ether groups and polyisocyanates.

The aminoplasts are obtained from the reaction of formaldehyde with an amine or amide. The most common amines or amides are melamine, urea, or benzoguanamine, and are preferred. However, the condensed products can be used with other amines or amides; for example, products condensed with glycoluril aldehyde, which give a high-melting crystalline product that is useful in powder coatings. While the aldehyde used is very often formaldehyde, other aldehydes such as acetaldehyde, crotonaldehyde, and benzaldehyde can be used. The aminoplast contains methylol groups and preferably at least a portion of these groups are etherified with an alcohol to modify the curing response. Any monohydric alcohol can be used for this purpose including methanol, ethanol, butanol, isobutanol, and hexane1. Preferably, the aminoplasts which are used are condensate products of formaldehyde with melamine, urea, or benzoguanamine etherified with an alcohol containing one to four carbon atoms. Other suitable crosslinking agents include the polyisocyanates. The polyisocyanate crosslinking agent can be a completely terminally capped polyisocyanate substantially free of free isocyanate groups, or it can contain free isocyanate functionality. The free isocyanate groups allow the curing of the composition at temperatures as low as the environment. When the cross-linking agent contains free isocyanate groups, the film-forming composition is preferably a two-pack composition (one package comprises the cross-linking agent and the other comprises the hydroxyl-functional polymer) in order to maintain stability during storage. The polyisocyanate can be an aliphatic or aromatic polyisocyanate or a mixture of the two. Diisocyanates are preferred, although higher polyisocyanates can be used in place of or in combination with the diisocyanates. Examples of suitable aliphatic diisocyanates are straight chain aliphatic diisocyanates such as 1,4-tetramethylene diisocyanate and 1,6-hexamethylene diisocyanate. Likewise, cycloaliphatic diisocyanates can be used. Examples include isophorone diisocyanate and 4, '-methylene-bis- (cyclohexyl isocyanate). Examples of suitable aromatic diisocyanates are p-phenylene diisocyanate, 4,4 '-diphenylmethane diisocyanate and 2,4- or 2,6-toluene diisocyanate. Examples of the suitable higher polyisocyanates are triphenylmethane-4,4 ', 4"-triisocyanate, 1,2,4-benzene triisocyanate and polymethylene polyphenyl isocyanate." Biurets and isocyanurates, including mixtures of the same, such as the isocyanurate of hexamethylene diisocyanate, the biuret of hexamethylene diisocyanate and the isocyanurate of isophorone diisocyanate.

Isocyanate prepolymers can also be used, for example, reaction products of polyisocyanates with polyols such as neopentyl glycol and trimethylolpropane or with polymeric polyols such as polycaprolactone diols and triols (ratio of NCO / OH equivalents greater than one).

Any suitable aliphatic, cycloaliphatic, or aromatic alkyl monoalcohol or phenolic compound can be used as a terminal protective agent for the end-capped polyisocyanate crosslinking agent in the composition of the present invention, including, for example, lower aliphatic alcohols such as methanol, ethanol, and n-butanol; cycloaliphatic alcohols such as cyclohexanol; aromatic alkyl alcohols such as phenylcarbinol and methylphenylcarbinol; and phenolic compounds such as the phenol itself and substituted phenols wherein the substituents do not affect the coating operations, such as cresol and nitrophenol. Glycol ethers can also be used as terminal protection agents. Suitable glycol ethers include ethylene glycol butyl ether, diethylene glycol butyl ether, ethylene glycol methyl ether and propylene glycol methyl ether. Other suitable terminal protective agents include oximes such as methylethyl oxime, acetone oxime and cyclohexanone oxime, lactams such as epsilon-caprolactam, and amines such dibutylamine. The crosslinking agent is typically present in the thermosetting compositions of the present invention in an amount of at least 10 weight percent, preferably at least 25 weight percent, based on the weight of total resin solids of the composition . The crosslinking agent is also typically present in the composition in an amount of less than 90 weight percent, preferably less than 75 weight percent, based on the weight of total resin solids of the composition. The amount of crosslinking agent present in the thermosetting composition of the present invention may range between any combination of these values, including the values quoted.

The equivalent ratio of hydroxyl groups of the polymer to the reactive functional groups of the crosslinking agent is typically in the range of 1: 0.5 to 1: 1.5, preferably 1: 0.8 to 1: 1.2. Normally the thermosetting composition will also preferably contain catalysts to accelerate the curing of the crosslinking agent with reactive groups of the polymer or polymers. Suitable catalysts for the curing of the aminoplast include acids such as acid phosphates and sulfonic acid or substituted sulfonic acid. Examples include dodecylbenzenesulfonic acid, paratoluenesulfonic acid, phenyl acid phosphate, ethylhexyl acid phosphate, and the like. Suitable catalysts for isocyanate curing include organotin compounds such as dibutyltin oxide, dioctyltin oxide, dibutyltin dilaurate, and the like. The catalyst is normally present in an amount from about 0.05 to about 5.0 weight percent, preferably from about 0.25 to about 2.0 weight percent, based on the total weight of the catalyst. resin solids of the thermosetting composition. The thermosetting composition of the present invention is preferably used as a film-forming composition (coating), and may contain adjunct ingredients conventionally used in such compositions. Optional ingredients such as, for example, plasticizers, surfactants, thixotropic agents, anti-gassing agents, organic co-solvents, flow controllers, anti-oxidants, UV light absorbers and similar conventional additives may be included in the composition. The technique. These ingredients are typically present up to about 40% by weight based on the total weight of resin solids. The thermosetting composition of the present invention is typically a liquid and may be water based, but usually it is solvent based. Suitable solvent carriers include the various esters, ethers, and aromatic solvents, including mixtures thereof, which are known in the art of coating formulation. The composition typically has a total solids content of about 40 to about 80 weight percent. The thermosetting composition of the present invention may contain coloring pigments conventionally used in surface coatings and may be used as a single coat; that is, a pigmented coating. Suitable pigments with coloration include, for example, inorganic pigments such as titanium dioxide, iron oxides, chromium oxide, lead chromate, and carbon black, and organic pigments such as phthalocyanine blue and phthalocyanine green. Mixtures of the aforementioned pigments can also be used. Suitable metal pigments include, in particular, aluminum flake, copper bronze flake and metal oxide coated mica, nickel flake, tin flake, and mixtures thereof. In general, the pigment is incorporated into the coating composition in amounts of up to 80% by weight based on the total weight of the coating solids. The metallic pigment is used in amounts of about 0.5 to about 25 weight percent based on the total weight of solids in the coating. As stated above, the thermosettable compositions of the present invention can be used in a method of coating a substrate comprising applying a thermosetting composition to the substrate, incorporating the thermosetting composition onto the substrate in the form of a substantially continuous film, and curing the thermosetting composition. The compositions can be applied to different substrates to which they adhere including wood, metals, glass, and plastic. The compositions can be applied by conventional means including brush application, dipping, flow coating, spraying and the like, but are very often applied by spraying. The usual spray mechanisms and equipment for air spraying and electrostatic spraying and manual or automatic methods can be used. Upon application of the composition to the substrate, the composition is allowed to incorporate to form a substantially continuous film on the substrate. Typically, the thickness of the film will be from about 0.01 to about 5 mils (from about 0.254 to about 127 microns), preferably from about 0.1 to about 2 mils (from about 2.54 to about 50.8 microns) thick. The film is formed on the surface of the substrate by expelling the solvent, i.e., organic solvent and / or water, from the film by heating or by a period of air drying. Preferably, the heating will only be for a short period of time, sufficient to ensure that any subsequent applied coating can be applied to the film without dissolving the composition. Suitable drying conditions will depend on the particular composition, but in general a drying time of about 1 to 5 minutes at a temperature of about 20-121 ° C (68-250 ° F) will be suitable. You can apply more than one layer of the composition to create an optimal appearance. Between layers, the previously applied layer may be subjected to vaporization of volatile fluids; that is, exposed to environmental conditions for approximately 1 to 20 minutes. The film-forming composition of the present invention is preferably used as a clear coating layer in a composite multi-component coating composition such as a "color-plus-clear coat" coating system, which includes at least one base layer pigmented or colored and at least one clear top layer. In this embodiment, the clear film forming composition can include the thermosetting composition of the present invention. The film-forming composition of the base layer in the clear-plus-clear coat system can be any of the compositions useful in coatings applications, particularly in automotive applications. The film-forming composition of the base layer comprises a resinous binder and a pigment to act as a colorant. Particularly useful resinous binders are acrylic polymers, polyesters, including alkyd, and polyurethanes. Polymers prepared using radical polymerization by atom transfer can also be used as resinous binders in the base layer. The compositions of the base layer may be with a solvent base or with an aqueous base. Base layers with an aqueous base of the clear-plus-color layer compositions are described in U.S. Patent No. 4,403,003, and the resinous compositions used to prepare these base layers can be used in the practice of this invention. Also, aqueous-based polyurethanes such as those prepared according to U.S. Patent No. 4,147,679 can be used as a resinous binder in the basecoat. Additionally, water-based coatings such as those described in U.S. Patent 5,071,904 may be used as a base coat.

The base layer contains pigments to confer color. Suitable pigments include those discussed above. In general, the pigment is incorporated into the coating composition in amounts of about 1 to 80 weight percent based on the weight of coating solids. The metallic pigment is used in amounts of about 0.5 to 25 weight percent based on the weight of coating solids. If desired, the composition of the base layer may contain additional materials well known in the art of formulated surface coatings, including those discussed above. These materials can constitute up to 40 percent by weight of the total weight of the coating composition. The basecoating compositions can be applied to different substrates to which they adhere by conventional means, but are very often applied by spraying. The usual spray mechanisms and equipment for air spraying or electrostatic spraying and manual or automatic methods can be used. During the application of the basecoating composition to the substrate, a film of the basecoat is formed on the substrate. Typically, the thickness of the base layer will be from about 0.01 to 5 mils (0.254 to 127 microns), preferably 0.1 to 2 mils (2.54 to 50.8 microns) in thickness.

After application of the basecoat to the substrate, a film is formed on the surface of the substrate by expelling the solvent from the basecoat film by heating or by a drying period with air, sufficient to ensure that the clearcoat can be applied to the substrate. the base layer without dissolving the first the composition of the base layer, still insufficient to fully cure the base layer. More than one base layer and multiple base layers can be applied to create an optimal appearance. Normally between layers, the previously applied layer is subjected to vaporization of volatile fluids. The composition of the clear top layer can be applied to the substrate coated with the base by any conventional coating mechanism such as brush application, spraying, dipping or flow coating, but spraying applications are preferred because of their gloss higher. Any of the known spraying mechanisms such as compressed air spraying, electrostatic spraying and manual or automatic methods can be employed. Upon application of the clear coating composition to the base coat, the coated substrate may be heated to cure the coating layer or layers. In the curing operation, the solvents are expelled and the film forming materials in the composition are crosslinked. The heating or curing operation is usually carried out at a temperature in the range of at least room temperature (in the case of crosslinking agents with free polyisocyanate) at 117 ° C (room at 350 ° F) but if necessary , lower or higher temperatures can be used to activate the crosslinking mechanisms according to need. The present invention is more specifically described in the following examples, which are intended to be merely illustrative, since numerous modifications and variations will be apparent to those skilled in the art. Unless otherwise specified, all parts and percentages are by weight.

Synthesis Examples A-C In the Synthesis Examples A-C, the preparation of hydroxyl-functional polymers used in Examples 1-3 of the coating composition is described. The hydroxyl functional polymer of Example A is a comparative polymer prepared by non-active radical polymerization. The hydroxyl functional polymers of Examples B and C are representative of the polymers useful in the thermosetting coating compositions of the present invention. The physical properties of the polymers of Examples A-C are summarized in Table 1. In Synthesis Examples A-C, the following abbreviations of monomers are used: isobutyl methacrylate (IBMA); and hydroxypropyl methacrylate (HPMA). Each of the polymers of Examples A-C was prepared from monomers comprising 60 weight percent IBMA monomer and 40 weight percent HPMA monomer, based on the total weight of monomers. The block copolymer structures shown in each of Examples B and C are general formulas representative of the block copolymer.

Example A A polymer with a comparative hydroxyl functionality was prepared by normalized, ie uncontrolled or non-active, radical polymerization from the ingredients listed in Table A.

Table A Ingredients Parts in Weight Load 1 xylene 500.0 n-butanol 125.0 Load 2 monomer HPMA 240.0 monomer IBMA 360.0 initiator (a) 30.0 Load 3 xylene 8.0 n-butanol 2.0 primer (a) 6.0 (a) initiator 2, 2'-azobis (2-methylbutanonitrile), obtained commercially from E.I. du Pont de Nemours and Company.

The charge 1 was heated to the reflux temperature at atmospheric pressure under a blanket of nitrogen in a 2 liter round bottom flask equipped with a rotating blade stirrer, reflux condenser, thermometer and a heating jacket coupled in a loop of feedback through a temperature controller, nitrogen inlet port, and two ports of addition. Under reflux conditions, Charge 2 was fed to the flask over a period of 3 hours. r the addition of Charge 2 was complete, the contents of the flask were refluxed for an additional hour. The contents of the flask were then cooled to 100 ° C and Charge 3 was added over a period of 10 minutes, followed by an interruption of 2 hours at 100 ° C. The contents of the flask were cooled and transferred to a suitable container. Example B A triblock copolymer with hydroxyl functionality useful in the thermosetting compositions of the present invention was prepared by radical polymerization by transferring atoms from the ingredients listed in Table B. The hydroxyl-functional block copolymer of this example is summarizes schematically as follows: (HPMA, IBMA) - (IBMA) - (HPMA) Table B Ingredients Parts in Weight Load 1 toluene 500.0 copper (II) bromide (b) 11.2 copper powder (c) 32.0 2.2 • -bipyridyl 78.0 Load 2 diethyl-2-brsmo-2-methylmalonate 125.0 Load 3 monomer HPMA 146, 0 monomer IBMA 144, 0 Load 4 toluene 500, 0 monomer IBMA 720, 0 Load 5 monomer HPMA 420, 0 (b) Copper (II) bromide was in the form of flakes and was obtained from Aldrich Chemical Company. (c) The copper powder had an average particle size of 25 microns, a density of 1 gram / cm 3, and was commercially obtained from OMG Americas. Charge 1 was heated and maintained at 50 ° C for one hour in a 2-liter 4-necked flask equipped with a motor-driven stainless steel stirring blade, a water-cooled condenser, and a heating jacket and a thermometer connected by means of a temperature control device by feedback. The contents of the flask were cooled to 25 ° C and Charge 2 was added over a period of 10 minutes. Charge 3 was then added over a period of 15 minutes, followed by heating the contents of the flask and stopping at 70 ° C for 2 hours. r completion of the 2 hour interruption, the contents of the flask were heated to 80 ° C, then Charge 4 was added over 15 minutes, followed by an interruption of 2 hours at 80 ° C.

The contents of the flask were then cooled to a temperature of 70 ° C, and Charge 5 was added over 15 minutes, followed by an interruption of 3 hours at 70 ° C. r completion of the 3-hour interruption, 200 grams of xylene and 100 grams of MAGNESOL synthetic magnesium silicate obtained commercially from The Dallas Group of America was added to the flask followed by mixing for 30 minutes at 70 ° C. The contents of the flask were filtered, and the filtered resin was vacuum distilled to a total solids content of 70 weight percent, based on the total weight.

Example C A triblock copolymer with hydroxyl functionality useful in the thermosetting compositions of the present invention was prepared by radical polymerization by transferring atoms from the ingredients listed in Table C. The hydroxyl-functional block copolymer of this example is summarizes schematically as follows: (IBMA) - (HPMA) - (IBMA) Table C Ingredients Parts in Weight Load 1 toluene 500, 0 copper bromide (II) (b) 11.2 copper powder (c) 21,5 2,2 '-bipyridyl 50,0 Load 2 diethyl-2-bromo-2-methylmalonate 85.0 Load 3 monomer IBMA 200,0 Load 4 monomer HPMA 190.0 Loading 5 monomer IBMA 90.0 Charge 1 was heated and maintained at 70 ° C for one hour in a 2-liter 4-necked flask equipped as described in Example B. The contents of the flask were cooled to 25 ° C. and Charge 2 was added over a period of 10 minutes, followed by the addition of Charge 3 over 15 minutes. After the addition of Charge 3 was complete, the contents of the flask were heated and maintained at 80 ° C for 2 hours. After completion of the 2-hour interruption, the contents of the flask were cooled to 70 ° C and Charge 4 was added over 15 minutes, followed by an interruption of 2 hours at 70 ° C. The contents of the flask were then heated to 80 ° C and Charge 5 was added over 15 minutes, followed by an interruption of 2 hours at 80 ° C. After completion of the 2 hour break, 200 grams of xylene and 100 grams of MAGNESOL synthetic magnesium silicate obtained commercially from The Dallas Group of America was added to the flask followed by mixing for 30 minutes at 70 ° C. The contents of the flask were filtered, and the filtered resin was vacuum distilled to a total solids content of 70 weight percent, based on the total weight.

Table 1 Physical Data of the Polymers of the Synthesis Examples A-C Example Example Example Example A B C Mn (d) 2,341 1,188 1,859 Mw 5,618 1,580 2,510 Mw / Mn 2,40 1,33 1,35 Percentage by weight of 49 70 70 solids (e) (d) The number average molecular weight (Mn) and the weight-average molecular weight (Mw) were determined by gel permeation chromatography (GPC) using polystyrene standards. (e) The percentage by weight of solids, based on the total weight was determined from samples of 0.2 grams at 110 ° C / l hour.

Examples of Coating Composition 1-3 Examples 2 and 3 are representative of the thermosetting coating compositions according to the present invention, although the coating composition of Example 1 is a comparative example. The coating compositions were prepared from the ingredients listed in Table 2.

Table 2 Coating Compositions Example Example Example 1 2 3 Polymer 124.2 0.0 0.0 Example A Polymer 0.0 73.6 0.0 Example B Polymer 0.0 0.0 105.4 Example C Agent 35.0 35.0 35.0 Melamine crosslinking (f) Additive 0.5 0.5 0.5 flow (g) DDBSA (h) 1.0 1.0 1.0 Stabilizer 3.0 3.0 3.0 UV (i) xylene 5.0 5.0 5.0 Ethyl 3-ethoxy-23.3 48.8 24.4 propionate (f) CYMEL 1130 melamine crosslinking agent obtained commercially from Cytec Industries. (g) poly (butyl acrylate) flow additive at 60 weight percent solids in xylene, based on the total weight, which has Mn = 6,700 and Mw = 2,600. (h) dodecylbenzenesulfonic acid. (i) TINUVIN 328 ultraviolet light stabilizer commercially available from Ciba-Geigy Corp., which describes it as [2'-Hydroxy-3 ', 5'-Di-amylphenyl] -2-H-benzotriazole.

The ingredients of Examples 1-3 of the coating composition were each carefully mixed in a suitable container. The physical properties of the liquid coating compositions were measured and the results are summarized in Table 3. The test panels were first coated with a base coat (white base coat DCT-6640, commercially available from PPG Industries, Inc. ), which was dried at 93 ° C for 5 minutes. The liquid coating compositions of Examples 1-3 were spray-applied onto the test panels with the basecoat white, and cured at 141 ° C for 30 minutes. The physical properties of the cured coatings were determined, and the results are summarized in Table 4.

Table 3 Physical Properties of Coating Compositions 1 - 3 Example Example Example 2 3 in Weight of Solids (j) 48.4 56.32.0 Viscosity (seconds) (k) 23 23 23 (j) The weight percent solids of the coating compositions was measured at 110 ° C for 60 minutes. minutes (k) The viscosity was determined by measuring the amount of time it took for the liquid coating composition to be emptied from a full Ford No. 4 cup, commercially available from Gardner Lab.

Table 4 Physical Properties of Cured Coatings Obtained from Coating Compositions 1 - 3 Example Example Example 1 2 3 Film thickness 48 38 41 cured (microns) Brightness at 20 ° C (1) 86 88 86 Image clarity (m) 82 94 80 Hardness Knoop (n) 12.5 10.4 13, 9% Brightness preserved 87 88 89 after the deterioration test (o) Pencil hardness (p) 2H H 2H Pencil hardness after 2H H 2H the spot application of xylene (q) (1) gloss values at 20 ° C were obtained using a BYK Gardner Haze-Gloss Meter according to the method of operation suggested by the manufacturer. (m) The values of the image clarity (DOI) of the cured coatings were obtained using a DOI DORIGON II meter according to the method of operation suggested by the manufacturer. DOI values of greater magnitude are indicative of softer coatings. (n) The Knoop hardness of the cured coatings was measured according to the American Standard Test Method (ASTM) D 1474-92 using a Tukon Microhardness Tester Model 300 (from Wilson Instruments, Division of Instron Corporation). The measuring device for the microhardness was operated with a weight of 25 grams in the indentator. The values of Knoop hardness of greater magnitude are- indicative of harder coatings.

It is generally considered that Knoop hardness values of 10 or greater are desirable. (o) The retention of the gloss percentage was determined by comparing the brightness measurements at 20 ° C (using a BYK Gardner Haze-Gloss Meter) taken before and after the deterioration test of the cured coatings. The coated test panels became slightly powdery with a BON-AMI abrasive coater (from Bon-Ami Company), the test panels that had become dusty were passed through 30 cycles in an Atlas AATCC Mar Tester Model CM- 5 (from Atlas Electrical Devices Co.). The deterioration measuring apparatus was operated with a felt cloth cover over the cylindrical acrylic finger of the deterioration measuring apparatus. A new felt cloth coating was used every 10 operating cycles of the deterioration measuring apparatus. After completing the 30 cycles of the sea test, the test panels were rinsed with cold running water, dried, and the brightness readings were taken at 20 °, and the percentage of brightness preserved was calculated using the following equation: (Reading of the gloss at 20 ° deteriorated / Reading of the brightness at 20 ° original) x 100. (p) The pencil hardness of a cured film is determined manually by trying to scratch the surface of the film with a series of pencils, ranging from pencils with a soft mine to those that have a harder mine. From the softest to the hardest, the series of hardness of the pencils is as follows: 4B, 3B, 2B, B, F, HB, H, 2H, 3H, 4H, 5H. The pencil hardness listed in Table 4 is that of the hardest pencil that did not scratch the surface of the solvent-treated film. (q) A drop of xylene having a diameter of about 1 to 1.5 cm was placed on the surface of the cured film for 3 minutes. The xylene drop was dried from the film, and the pencil hardness of the film where the drop had been was determined, as previously described herein.

The results summarized in Table 4 show that the thermosetting coating compositions according to the present invention, ie, of Examples 2 and 3, provide cured coatings having properties similar to those of the cured coatings obtained from comparative compositions, ie, of Example 1. In addition, the results summarized in Table 3 show that the liquid coating compositions according to the present invention are say, of Examples 2 and 3, they have a weight percent solids greater than the same viscosity as the comparative liquid coating compositions, ie, of Example 1. The present invention has been described with reference to specific details of the concrete achievements of it. It is not intended that such details be considered as limitations of the scope of the invention unless they are included in the appended claims.

Claims

1. A thermosetting composition comprising .- (a) a crosslinking agent having at least two functional groups that are reactive with hydroxyl groups; and (b) a hydroxyl-functional, non-gelled polymer prepared by radical polymerization by atom transfer, in the presence of an initiator having at least one group capable of radical transfer, and wherein the polymer contains at least one of the following structures of the polymer chain: -. { (M) p- (G) q} x- or -. { (G) q- (M) P} X-wherein M is a residue, lacking hydroxyl functionality, of at least one monomer susceptible to ethylenically unsaturated radical polymerization; G is a residue, having hydroxyl functionality, of at least one monomer capable of ethylenically unsaturated radical polymerization; p and q represent the average number of remains that appear in a block of debris in each structure of the polymer chain; And P, 1, and x are each independently selected for each structure so that said hydroxyl functional polymer has a number average molecular weight of at least 250.

2. The thermosetting composition of claim 1, wherein the hydroxyl functional polymer has a number average molecular weight of 500 to 16,000, and a polydispersity index of less than 2.0.

3. The thermosetting composition of claim 1, wherein said initiator is selected from the group consisting of linear or branched aliphatic compounds, cycloaliphatic compounds, aromatic compounds, polycyclic aromatic compounds, heterocyclic compounds, sulfonylic compounds, sulfenyl compounds, carboxylic acid esters, polymeric compounds, and mixtures thereof, each having at least one group capable of radical transfer.

4. The thermosetting composition of claim 3, wherein said initiator is selected from the group consisting of halomethane, methylene halide, haloform, carbon tetrahalide, methanesulfonyl halide, p-toluenesulfonyl halide, methanesulfenyl halide, p-toluenesulfenyl halide, halide of l-phenylethyl, 2-halopropionitrile, C? -C6 alkyl ester of 2-halocarboxylic acid C? -C6, p-halomethylstyrene, mono-hexakis (a-halo-alkyl Ci-Ce) benzene, diethyl-2-malonate halo-2-methyl, benzyl halide, ethyl 2-bromoisobutyrate and mixtures thereof.

5. The thermosetting composition of claim 1, wherein the polymer has a hydroxyl equivalent weight of 116 to 10,000 grams / equivalent.

6. The thermosetting composition of claim 1, wherein p and q are each independently selected within the range of 0 to 100 for each segment x and for each structure, and where the sum of p and q is greater than zero for each segment x and q is greater than zero for minus one segment x.

7. The thermosetting composition of claim 1, wherein x for each structure is independently in the range of at least 1 to 100.

The thermosetting composition of claim 1, wherein M is derived from at least one of the vinyl monomers, monomers ( met) allylic, and olefins.

9. The thermosetting composition of claim 1, wherein M is derived from at least one of the alkyl (meth) acrylates having from 1 to 20 carbon atoms in the alkyl group, unsaturated aromatic monomers and olefins.

10. The thermosetting composition of claim 1, wherein the hydroxyl functional polymer contains at least one of the following structures in the polymer chain: f- [. { (M) p- (G) q} x- (M) r-T] z or f- [. { (G) q- (M) p} x- (G) s-T] z where r and s are each independently in the range of 0 to 100; f is or is derived from a residue of the free initiator of the group susceptible to radical transfer; x is in the range of at least 1 to 100; p and q are each independently within the values 0 to 100 for each segment x; the sum of p and q is greater than zero for each segment x; q is greater than zero for at least one segment x; z is at least 1; T is or is derived from the group susceptible to radical transfer of the initiator; and the hydroxyl functional polymer has a polydispersity index of less than 2.0.

11. The thermosetting composition of claim 10, wherein the hydroxyl functional polymer has a number average molecular weight of 500 to 16,000, and a polydispersity index of less than 1.8.

12. The thermosetting composition of claim 10, wherein T is a halide.

13. The thermosetting composition of claim 10, wherein T is derived from a post-reaction dehalogenation.

14. The thermosetting composition of the claim 13, wherein said post-reaction de-halogenation comprises contacting said polymer with hydroxyl functionality with an ethylenically unsaturated compound susceptible to limited radical polymerization.

15. The thermosetting composition of the claim 14, wherein said ethylenically unsaturated compound susceptible to limited radical polymerization is selected from the group consisting of 1,1-dimethylethylene, 1,1-diphenylethylene, isopropenyl acetate, alpha-methylstyrene, 1,1-dialkoxyolefin and combinations thereof.

16. The thermosetting composition of claim 1, wherein said crosslinking agent is selected from polyisocyanates and aminoplasts containing methylol and / or methylol ether groups.

17. The thermosetting composition of claim 16, wherein said crosslinking agent is a blocked polyisocyanate.

18. The thermosetting composition of claim 1, wherein said hydroxyl functional polymer is selected from the group consisting of linear polymers, branched polymers, hyper-branched polymers, star polymers, graft polymers and mixtures thereof.

19. The thermosetting composition of claim 1, wherein said hydroxyl functional polymer has a polydispersity index of less than 1.50.

20. The thermosetting composition of claim 1, wherein the equivalent ratio of hydroxyl groups in (b) to the reactive functional groups in (a) is within the range of 1: 0.5 to 1: 1.5.

21. The thermosetting composition of claim 1, wherein (a) is present in amounts of 10 to 90 percent by weight and (b) is present in amounts of 10 to 90 percent by weight, based on the total weight of resin solids. of the thermosetting composition.

22. The thermosetting composition of claim 1, wherein G is derived from at least one monomer capable of ethylenically unsaturated radical polymerization selected from hydroxyalkyl acrylates and hydroxyalkyl methacrylates having from 2 to 4 carbon atoms in the hydroxyalkyl group.

23. A method of coating a substrate comprising: (a) applying a thermosetting composition to the substrate; (b) incorporating the thermosetting composition onto the substrate in the form of a substantially continuous film; and (c) curing the thermosetting composition, wherein the thermosetting composition comprises: (i) a crosslinking agent having at least two functional groups that are reactive with hydroxyl groups; and (ii) a hydroxyl-functional, non-gelled polymer prepared by radical polymerization by atom transfer, in the presence of an initiator having at least one group capable of radical transfer, and wherein the polymer contains at least one of the following structures of the polymer chain: -. { (M) p- (G) q} x- or -. { (G) q- (M) P} X-wherein M is a residue, lacking hydroxyl functionality, of at least one monomer susceptible to ethylenically unsaturated radical polymerization; G is a residue, having hydroxyl functionality, of at least one monomer capable of ethylenically unsaturated radical polymerization; p and q represent the average number of remains that appear in a block of debris in each structure of the polymer chain; And P, Qi and x are each independently selected for each structure such that said hydroxyl functional polymer has a number average molecular weight of at least 250.

24. The method of claim 23, wherein the hydroxyl functional polymer has a number average molecular weight of 500 to 16,000, and a polydispersity index of less than 2.0.

25. The method of claim 23, wherein said initiator is selected from the group consisting of linear or branched aliphatic compounds, cycloaliphatic compounds, aromatic compounds, polycyclic aromatic compounds, heterocyclic compounds, sulfonylic compounds, sulfenyl compounds, carboxylic acid esters, polymeric compounds, and mixtures thereof, each having at least one group capable of radical transfer.

26. The method of claim 25, wherein said initiator is selected from the group consisting of halomethane, methylene halide, haloform, carbon tetrahalide, methanesulfonyl halide, p-toluenesulfonyl halide, methanesulfenyl halide, p-toluenesulfenyl halide, halide 1-phenylethyl, 2-halopropionitrile, C? -C6 alkyl ester of 2-halocarboxylic acid C? -C6, p-halomethylstyrene, mono-hexakis (-halo-C? -C6 alkyl) -benzene, diethyl-2-malonate halo-2-methyl, benzyl halide, ethyl 2-bromoisobutyrate and mixtures thereof.

27. The method of claim 23, wherein the polymer has a hydroxyl equivalent weight of 116 to 10,000 grams / equivalent.

28. The method of claim 23, wherein p and q are each independently selected within the range of 0 to 100 for each segment x and for each structure, and where the sum of p and q is greater than zero for each segment x and q is greater than zero for at least a segment x.

29. The method of claim 23, wherein x for each structure is independently in the range of at least 1 to 100.

30. The method of claim 23, wherein M derives from at least one of the vinyl monomers, (meth) allyl monomers, and olefins.

31. The method of claim 23, wherein M is derived from at least one of the alkyl (meth) acrylates having from 1 to 20 carbon atoms in the alkyl group, unsaturated aromatic monomers and olefins.

32. The method of claim 23, wherein the hydroxyl functional polymer contains at least one of the following structures in the polymer chain: f- [. { (M) p- (G) q} x- (M) r-T] z or f- [. { (G) q- (M) p} x- (G) s-T] z where r and s are each independently in the range of 0 to 100; f is or is derived from a residue of the free initiator of the group susceptible to radical transfer; x is in the range of at least 1 to 100; p and q are each independently within the values 0 to 100 for each segment x; the sum of p and q is greater than zero for each segment x; q is greater than zero for at least one segment x; z is at least 1; T is or is derived from the group susceptible to radical transfer of the initiator; and the hydroxyl functional polymer has a polydispersity index of less than 2.0.

33. The method of claim 32, wherein the hydroxyl functional polymer has a number average molecular weight of 500 to 16,000, and a polydispersity index of less than 1.8.

34. The method of claim 32, wherein T is a halide.

35. The method of claim 32, wherein T derives from a post-reaction dehalogenation.

36. The method of claim 35, wherein said post-reaction de-halogenation comprises contacting said polymer with hydroxyl functionality with an ethylenically unsaturated compound susceptible to limited radical polymerization.

37. The method of claim 36, wherein said ethylenically unsaturated compound susceptible to limited radical polymerization is selected from the group consisting of 1,1-dimethylethylene, 1,1-diphenylethylene, isopropenyl acetate, alpha-methylstyrene, 1,1-dialkoxyolefin and combinations thereof.

38. The method of claim 23, wherein said crosslinking agent is selected from polyisocyanates and aminoplasts containing methylmethyl and / or methylol ether groups.

39. The method of claim 23, wherein said hydroxyl functional polymer is selected from the group consisting of linear polymers, branched polymers, hyper-branched polymers, star polymers, graft polymers and mixtures thereof.

40. The method of claim 23, wherein said hydroxyl functional polymer has a polydispersity index of less than 1.50.

41. The method of claim 23, wherein the equivalent ratio of hydroxyl groups in (ii) to the reactive functional groups in (i) is within the range of 1: 0.5 to 1: 1.5.

42. The method of claim 23, wherein (i) is present in amounts of 10 to 90 percent by weight and (ii) is present in amounts of 10 to 90 percent by weight, based on the total weight of solids of resin of the thermosetting composition.

43. The method of claim 23, wherein G is derived from at least one monomer capable of ethylenically unsaturated radical polymerization selected from hydroxyalkyl acrylates and hydroxyalkyl methacrylates having from 2 to 4 carbon atoms in the hydroxyalkyl group.

44. The method of claim 23, wherein the thermosetting composition is applied in the form of a clear layer on a colored base layer to form a clear-plus-clear composite layer coating.

45. A substrate coated by the method of claim 23.

46. A composite multi-component coating composition comprising a base layer deposited from a pigmented film-forming composition and a transparent top layer applied over the base layer where the transparent top layer is deposited from a clear film-forming composition and is a thermosetting composition comprising: (a) a crosslinking agent having at least two functional groups that are reactive with hydroxyl groups; and (b) a hydroxyl-functional, non-gelled polymer prepared by radical polymerization by atom transfer, in the presence of an initiator having at least one group capable of radical transfer, and wherein the polymer contains at least one of the following structures of the polymer chain: -. { (M) p- (G) q} x- or -. { (G) q- (M) P} X-wherein M is a residue, lacking hydroxyl functionality, of at least one monomer susceptible to ethylenically unsaturated radical polymerization; G is a residue, having hydroxyl functionality, of at least one monomer capable of ethylenically unsaturated radical polymerization; p and q represent the average number of remains that appear in a block of debris in each structure of the polymer chain; and p, q, and x are each independently selected for each structure so that said hydroxyl functional polymer has a number average molecular weight of at least 250.

47. The composite multi-component coating composition of claim 46, wherein the hydroxyl-functional polymer has a number average molecular weight of 500 to 16,000, and a polydispersity index of less than 2.0.

48. The composite multi-component coating composition of claim 46, wherein said initiator is selected from the group consisting of linear or branched aliphatic compounds, cycloaliphatic compounds, aromatic compounds, polycyclic aromatic compounds, heterocyclic compounds, sulfonyl compounds, sulfenyl compounds, acid esters carboxylic, polymeric compounds, and mixtures thereof, each having at least one group capable of radical transfer.

49. The composite multi-component coating composition of claim 48, wherein said initiator is selected from the group consisting of halomethane, methylene halide, haloform, carbon tetrahalide, methanesulfonyl halide, p-toluenesulfonyl halide, methanesulfenyl halide, halide p-toluenesulfenyl, 1-phenylethyl halide, 2-halopropionitrile, C? -C6 alkyl ester of 2-halocarboxylic acid C? -C6, p-halomethylstyrene, mono-hexakis (a-halo-C? -C3 alkyl) benzene, diethyl-2-halo-2-methyl ester, benzyl halide, ethyl 2-bromoisobutyrate and mixtures thereof.

50. The composite multi-component coating composition of claim 46, wherein the polymer has a hydroxyl equivalent weight of 116 to 10,000 grams / equivalent.

51. The composite multi-component coating composition of claim 40, wherein p and q are each independently selected within the range of 0 to 100 for each segment x and for each structure, and where the sum of p and q is greater than zero for each segment x and q is greater than zero for at least one segment x.

52. The composite multi-component coating composition of claim 46, wherein x for each structure is independently in the range of at least 1 to 100

53. The composite multi-component coating composition of claim 46, wherein M is derived from at least one of the vinyl monomers, (meth) allyl monomers, and olefins.

54. The composite multi-component coating composition of claim 46, wherein M is derived from at least one of the alkyl (meth) acrylates having from 1 to 20 carbon atoms in the alkyl group, unsaturated aromatic monomers and olefins.

55. The composite multi-component coating composition of claim 46, wherein the hydroxyl functional polymer contains at least one of the following structures in the polymer chain: f- [. { (M) p- (G) q} x- (M) r-T] z or f- [. { (G) q- (M) p} x- (G) s-T] z where r and s are each independently in the range of 0 to 100; f is or is derived from a residue of the free initiator of the group susceptible to radical transfer; x is in the range of at least 1 to 100; p and q are each independently within the values 0 to 100 for each segment x; the sum of p and q is greater than zero for each segment x; q is greater than zero for at least one segment x; z is at least 1; T is or is derived from the group susceptible to radical transfer of the initiator; and the hydroxyl functional polymer has a polydispersity index of less than 2.0.

56. The composite multi-component coating composition of claim 55, wherein the hydroxyl functional polymer has a number average molecular weight of 500 to 16,000, and a polydispersity index of less than 1.8.

57. The composite multi-component coating composition of claim 55, wherein T is a halide.

58. The composite multi-component coating composition of claim 55, wherein T derives from a post-reaction dehalogenation.

59. The composite multi-component coating composition of claim 58, wherein said post-reaction de-halogenation comprises contacting said polymer with hydroxyl functionality with an ethylenically unsaturated compound susceptible to limited radical polymerization.

60. The composite multi-component coating composition of claim 59, wherein said ethylenically unsaturated compound susceptible to limited radical polymerization is selected from the group consisting of 1,1-dimethylethylene, 1,1-diphenylethylene, isopropenyl acetate, alpha-methylstyrene, 1,1-dialkoxyolefin and combinations thereof.

61. The composite multi-component coating composition of claim 46, wherein said crosslinking agent is selected from polyisocyanates and aminoplasts containing methylol and / or methylol ether groups.

62. The composite multi-component coating composition of claim 46, wherein said hydroxyl-functional polymer is selected from the group consisting of linear polymers, branched polymers, hyper-branched polymers, star polymers, graft polymers and mixtures thereof.

63. The composite multi-component coating composition of claim 46, wherein said hydroxyl-functional polymer has a polydispersity index of less than 1.50.

64. The composite multi-component coating composition of claim 46, wherein the equivalent ratio of hydroxyl groups in (b) to the reactive functional groups in (a) is within the range of 1: 0.5 to 1: 1, 5.

65. The composite multi-component coating composition of claim 46, wherein (a) is present in the clear film-forming composition in amounts of 10 to 90 percent by weight and (b) is present in the clear film-forming composition in amounts of 10 to 90 percent by weight, based on the total weight of resin solids of the clear film-forming composition.

66 The composite multi-component coating composition of claim 46, wherein G is derived from at least one ethylenically unsaturated radical polymerizable monomer selected from hydroxyalkyl acrylates and hydroxyalkyl methacrylates having from 2 to 4 carbon atoms in the hydroxyalkyl group . SUMMARY A thermosetting composition is provided comprising: (a) a crosslinking agent having at least two functional groups that are reactive with hydroxyl groups; and (b) a hydroxyl-functional, non-gelled polymer prepared by radical polymerization by atom transfer in the presence of an initiator having at least one group capable of radical transfer. The polymer contains at least one of the following structures of the polymer chain: -. { (M) p- (G) q} x-o -. { (G) q- (M) p} x- where M is a residue, which lacks hydroxyl functionality, of at least one monomer capable of ethylenically unsaturated radical polymerization; G is a residue, having hydroxyl functionality, of at least one monomer capable of ethylenically unsaturated radical polymerization; p and q represent the average number of remains that appear in a block of debris in each structure of the polymer chain; and p, q, and x are each independently selected for each structure so that the hydroxyl functional polymer has a number average molecular weight of at least 250. Methods of coating a substrate using the compositions of the invention are also provided by the present invention. the present invention and the substrates coated by such methods, as well as the coatings of color layer-plus-clear composite layer.