阅读说明：本技术 具有改进的耐刮擦性的涂层 (Coating with improved scratch resistance ) 是由 斯泰西·吉姆·马什 菲利普·杰罗姆·盖革 约翰·埃文·布瓦索 于 2019-10-07 设计创作，主要内容包括：本发明涉及用于涂层的脂族聚酯树脂。更具体地说,本发明涉及含有2,2,4,4-四甲基-1,3-环丁二醇(TMCD)的脂族聚酯树脂,当将其配制成1K汽车清漆时,其显示出改进的耐刮擦性。这些聚酯可以用作清漆粘合剂中的唯一树脂,或者与氨基甲酸酯官能化的丙烯酸树脂和/或羟基官能化的丙烯酸树脂和聚酯树脂组合使用。(The present invention relates to aliphatic polyester resins for coatings. More particularly, the present invention relates to aliphatic polyester resins containing 2,2,4, 4-tetramethyl-1, 3-cyclobutanediol (TMCD) which exhibit improved scratch and mar resistance when formulated into 1K automotive varnishes. These polyesters may be used as the sole resin in the varnish binder or in combination with the urethane-functionalized acrylic resin and/or the hydroxyl-functionalized acrylic and polyester resins.)

1. A coating, comprising:

A. from about 2 wt% to about 50 wt%, based on the total weight of (A), (B) and (C), of a curable aliphatic polyester resin comprising:

i. diacid residues comprising at least 90 mole percent of the residues of at least one aliphatic diacid, of which from 0 to 40 mole percent are cycloaliphatic diacids and from 60 to 100 mole percent are linear diacids containing from 4 to 12 carbons, based on the total moles of diacid residues;

a diol residue comprising: a) about 25 to 100 mole%, based on the total moles of diol residues, of residues of a diol having the structure:

wherein R is₁、R₂、R₃And R₄Each independently represents an alkyl group, and b) 0 to 75 mol%, based on the total number of moles of diol residues, of C₂-C₂₀A diol;

from about 5 mole% to about 80 mole% of residues of at least one polyol, based on the total moles of diol and polyol residues;

B. from about 15 wt% to about 85 wt%, based on the total weight of (a), (B), and (C), of at least one acrylic copolymer of ethylenically unsaturated monomers containing urethane and/or hydroxyl functional groups;

C. from about 10 wt% to about 50 wt%, based on the total weight of (a), (B), and (C), of at least one crosslinking agent comprising at least one compound that reacts with carbamate and/or hydroxyl groups; and

D. about 10 to 60 wt% of at least one non-aqueous solvent based on the total weight of (A), (B), (C) and (D).

2. The coating of claim 1, wherein the aliphatic diacid is a cyclic aliphatic dicarboxylic acid compound, a diester derivative thereof, an anhydride thereof, or a combination thereof.

3. The coating of claim 2, wherein the aliphatic diacid is selected from the group consisting of: 1, 4-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, hexahydrophthalic anhydride, methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, 5-norbornene-2, 3-dicarboxylic acid, 2, 3-norbornane dicarboxylic anhydride and mixtures thereof.

4. The coating of claim 1, wherein the non-cyclic aliphatic diacid is an open chain aliphatic dicarboxylic acid compound, a diester derivative thereof, an anhydride thereof, or a combination thereof.

5. The coating of claim 4, wherein the acyclic aliphatic diacid is selected from the group consisting of: succinic acid, glutaric acid, adipic acid, itaconic anhydride, itaconic acid, citraconic anhydride, citraconic acid, pimelic acid, suberic acid, dodecanedioic acid, sebacic acid, azelaic acid, and combinations thereof.

6. The coating of claim 1, wherein the diol ii a) is selected from the group consisting of: 2,2,4, 4-tetramethylcyclobutane-1, 3-diol (TMCD), 2,4, 4-tetraethylcyclobutane-1, 3-diol, 2,4, 4-tetra-n-propylcyclobutane-1, 3-diol, 2,4, 4-tetra-n-butylcyclobutane-1, 3-diol, 2,4, 4-tetra-n-pentylcyclobutane-1, 3-diol, 2,4, 4-tetra-n-hexylcyclobutane-1, 3-diol, 2,4, 4-tetra-n-heptylcyclobutane-1, 3-diol, 2,4, 4-tetra-n-octylcyclobutane-1, 3-diol, 2-dimethyl-4, 4-diethylcyclobutane-1, 3-diol, 2-ethyl-2, 4, 4-trimethylcyclobutane-1, 3-diol, 2, 4-dimethyl-2, 4-diethyl-cyclobutane-1, 3-diol, 2, 4-dimethyl-2, 4-di-n-propylcyclobutane-1, 3-diol, 2, 4-n-dibutyl-2, 4-diethylcyclobutane-1, 3-diol, 2, 4-dimethyl-2, 4-diisobutylcyclobutane-1, 3-diol and 2, 4-diethyl-2, 4-diisopentylcyclobutane-1, 3-diol.

7. The coating of claim 1, wherein the diol iib) is selected from the group consisting of: 2, 2-dimethyl-1, 3-propanediol, 1, 2-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol, 1, 4-cyclohexanedimethanol, 2, 4-trimethyl-1, 3-pentanediol, hydroxypivalic acid neopentyl glycol monoester, 2-methyl-1, 3-propanediol, 2-butyl-2-ethyl-1, 3-propanediol, 2-ethyl-2-isobutyl-1, 3-propanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 2,4, 4-tetramethyl-1, 6-hexanediol, 1, 10-decanediol, 1, 4-benzenedimethanol, 1, 3-dimethanol, 2, 4-decanediol, 2, 3-butanediol, 2-methyl-1, 3-propanediol, 2-ethyl-2-isobutyl-1, 3-propanediol, 1, 3-butanediol, Ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, and 2, 2-bis (hydroxymethyl) propionic acid.

8. The coating of claim 1, wherein the polyol iii) is a saturated or unsaturated aliphatic or cycloaliphatic C₂-C₂₀A compound is provided.

9. The coating of claim 8, wherein the polyol is selected from the group consisting of: 1,1, 1-trimethylolpropane, 1,1, 1-trimethylolethane, glycerol, pentaerythritol, erythritol, threitol, dipentaerythritol, sorbitol, and mixtures thereof.

10. The coating of claim 1 wherein the crosslinker comprises at least one melamine compound selected from the group consisting of hexamethoxymethylmelamine, tetramethoxymethylbenzylamine, tetramethoxymethylurea, and mixed butoxy/methoxy substituted melamines.

11. A coating, comprising:

A. from about 2 wt% to about 50 wt%, based on the total weight of (A), (B) and (C), of a curable aliphatic polyester resin comprising:

i. diacid residues comprising at least 90 mole percent of the residues of the compound 0 to 40 mole percent hexahydrophthalic anhydride and 60 to 100 mole percent adipic acid, based on the total moles of diacid residues;

a diol residue comprising: a) about 25 to 100 mole%, based on the total moles of diol residues, of 2,2,4, 4-tetramethyl-1, 3-cyclobutanediol residues, based on the total moles of diol residues, and b) 0 to 75 mole%, based on the total moles of diol residues, of neopentyl glycol; and

from about 5 to about 80 mole percent trimethylolpropane residues, based on the total moles of diol and polyol residues;

B. from about 15 wt% to about 85 wt%, based on the total weight of (a), (B), and (C), of at least one acrylic copolymer of ethylenically unsaturated monomers containing urethane and/or hydroxyl functional groups;

C. from about 10 wt% to about 50 wt%, based on the total weight of (a), (B), and (C), of at least one crosslinking agent comprising at least one compound that reacts with carbamate and/or hydroxyl groups; and

D. from about 10 wt% to 60 wt% of at least one non-aqueous solvent based on the total weight of (A), (B), (C) and (D).

12. A coating, comprising:

A. from about 2 wt% to about 50 wt%, based on the total weight of (A), (B) and (C), of a curable aliphatic polyester resin comprising:

i. diacid residues comprising at least 90 mole percent of the residues of at least one aliphatic diacid, of which from 0 to 40 mole percent are cycloaliphatic diacids and from 60 to 100 mole percent are linear diacids containing from 4 to 12 carbons, based on the total moles of diacid residues;

diol residues comprising a) 25 to 100 mole%, based on the total moles of diol residues, of residues of 2,2,4, 4-tetramethyl-1, 3-cyclobutanediol; and b) 0 to 75 mole%, based on the total moles of diol residues, of C₂-C₂₀A diol; and

from about 5 mole% to about 80 mole%, based on the total moles of diol and polyol residues, of residues of at least one polyol selected from the group consisting of: trimethylolpropane, pentaerythritol, trimethylolethane, erythritol, threitol, dipentaerythritol, sorbitol, and glycerol;

B. from about 15 wt% to about 85 wt%, based on the total weight of (a), (B) and (C), of at least one acrylic copolymer of ethylenically unsaturated monomers containing urethane and/or hydroxyl functional groups;

C. from about 10 wt% to about 50 wt%, based on the total weight of (a), (B), and (C), of at least one crosslinking agent comprising at least one compound that reacts with carbamate and/or hydroxyl groups; and

D. about 10 to 60 wt% of at least one non-aqueous solvent based on the total weight of (A), (B), (C) and (D).

Technical Field

The invention relates to aliphatic polyester resins for coatings (coating). More particularly, the present invention relates to aliphatic polyester resins containing 2,2,4, 4-tetraalkylcyclobutane-1, 3-diol (TACD) which exhibit improved scratch and mar resistance when formulated into 1K automotive clear (clearcoat). These aliphatic polyesters can be used in combination with acrylic resins and/or other polyester resins and/or other suitable resins (neither polyester nor acrylic, but which will react with the melamine crosslinker) to improve scratch resistance without suffering from a compromise (tradeoff) in other varnish properties such as hardness.

Background

As part of the wet-on-wet (wet-on-wet) body coating process, automobile manufacturers introduced one-component (1K) acrylic/melamine crosslinked varnishes in the 1980 s. These varnishes remain the most common varnish used today due to their cost/performance balance relative to the more expensive 2K polyurethane systems. Despite good mechanical properties, the scratch resistance of 1K acrylic/melamine varnishes is poor. This results in a poor appearance of the car and translates into consumer dissatisfaction with the manufacturer.

In the case of varnish scratching, there are two modes of damage, plastic deformation and fracture of the cured film. Plastic deformation or defects (mar) are caused by micro-wiping, such as those experienced during automatic car washing. These imperfections recover over time upon exposure to heat from the sun due to the elastic behavior of the varnish. The rupture or tearing of the film (e.g., severe damage to keys, nails, or tree branches) is permanent and does not recover. The soft varnish may be formulated to achieve viscoelastic flow to promote recovery after imperfections. They will likely be more susceptible to environmental attack and moisture (humidity) damage. Harder varnishes can be formulated to be more resistant to cracking, chemical and moisture, but over time the appearance is impaired by micro-scratches which make the varnish look more diffuse and less mirror-like. The combination of these two generally results in some compromise in performance.

In order to improve the scratch resistance of 1K acrylic/melamine varnishes, paint formulators often replace a portion of the acrylic resin with a "softer" resin having a low glass transition temperature. This soft resin may be another acrylic resin or polyester. Although the scratch resistance of the varnish due to plastic deformation can be improved, its hardness, chemical resistance and deep scratch resistance and fracture resistance may be deteriorated.

Thus, there is a need for a polymer resin that exhibits improved scratch resistance when formulated into a 1K automotive varnish, without suffering from a compromise in other varnish characteristics (such as hardness).

Disclosure of Invention

It has been found that aliphatic polyester resins containing 2,2,4, 4-tetraalkylcyclobutane-1, 3-diol (TACD), particularly 2,2,4, 4-tetramethyl-1, 3-cyclobutanediol (TMCD), exhibit improved scratch and mar resistance when formulated into 1K acrylic/melamine automotive varnishes. These aliphatic polyesters may be used in combination with acrylic resins and/or other polyester resins and/or other suitable resins (which are neither polyesters nor acrylic resins, but will react with a melamine crosslinker) to improve scratch resistance without suffering from compromises in other varnish properties (such as hardness).

The invention is set forth in the appended claims.

The present invention provides a coating comprising:

A. from about 2 weight percent (wt%) to about 50 wt% of a curable aliphatic polyester resin comprising, based on the total weight of (A), (B), and (C):

i. diacid residues comprising at least 90 mole percent (mole percent), based on the total moles of diacid residues, of the residues of at least one aliphatic diacid, of which 0-40 mole percent is a cycloaliphatic diacid and 60-100 mole percent is a linear diacid containing 4 to 12 carbons;

diol residues comprising, based on the total moles of diol residues: a) 25 to 100 mole percent, based on the total moles of diol residues, of 2,2,4, 4-tetraalkylcyclobutane-1, 3-diol (TACD) residues, and b) based on the total moles of diol residuesC in an amount of 0 to 75 mol%₂-C₂₀A diol; and; and

from about 5 mole% to about 80 mole%, based on the total moles of diol and polyol residues, of residues of at least one polyol selected from the group consisting of: trimethylolpropane, pentaerythritol, trimethylolethane, erythritol, threitol, dipentaerythritol, sorbitol, and glycerol;

B. about 15 to about 85 weight percent of an acrylic copolymer of at least one ethylenically unsaturated monomer containing urethane and/or hydroxyl functional groups, based on the total weight of (A), (B) and (C);

C. about 10 wt% to about 50 wt% of at least one crosslinking agent comprising at least one compound reactive with carbamate and/or hydroxyl groups, based on the total weight of (a), (B), and (C); and

D. about 10 to 60 wt% of at least one non-aqueous solvent, based on the total weight of (A), (B), (C) and (D).

The present invention also provides a coating comprising:

A. from about 2 wt% to about 50 wt% of a curable aliphatic polyester resin comprising, based on the total weight of (A), (B) and (C):

i. diacid residues comprising at least 90 mole percent of the residues of at least one aliphatic diacid, based on the total moles of diacid residues, of which from 0 to 40 mole percent are cycloaliphatic diacids and from 60 to 100 mole percent are linear diacids containing from 4 to 12 carbons;

diol residues comprising, based on the total moles of diol residues: a) 25 to 100 mole percent, based on the total moles of diol residues, of 2,2,4, 4-tetramethylcyclobutane-1, 3-diol (TMCD) residues, and b) 0 to 75 mole percent, based on the total moles of diol residues, of C₂-C₂₀A diol; and

from about 5 mole% to about 80 mole%, based on the total moles of diol and polyol residues, of residues of at least one polyol selected from the group consisting of: trimethylolpropane, pentaerythritol, trimethylolethane, erythritol, threitol, dipentaerythritol, sorbitol, and glycerol;

B. about 15 to about 85 weight percent of an acrylic copolymer of at least one ethylenically unsaturated monomer containing urethane and/or hydroxyl functional groups, based on the total weight of (A), (B) and (C);

C. about 10 wt% to about 50 wt% of at least one crosslinking agent comprising at least one compound reactive with carbamate and/or hydroxyl groups, based on the total weight of (a), (B), and (C); and

D. about 10 to 60 wt% of at least one non-aqueous solvent, based on the total weight of (A), (B), (C) and (D).

Detailed Description

Unless otherwise indicated, all numbers expressing quantities of ingredients, properties (such as molecular weight), reaction conditions, and so forth, used in the specification and claims are to be understood as being modified in all instances by the term. Unless indicated to the contrary, the numerical parameters set forth in the following specification and attached claims are approximations that may vary depending upon the desired properties sought to be obtained by the present invention. At the very least, each numerical parameter should be construed in light of the number of reported significant digits and by applying ordinary rounding techniques. Moreover, the ranges stated in the disclosure and claims are intended to include the entire range specifically, and not just the endpoints. For example, the stated range of 0 to 10 is intended to disclose: all integers between 0 and 10 such as, for example, 1,2, 3, 4, etc.; all decimals between 0 and 10, e.g., 1.5, 2.3, 4.57, 6.1113, etc.; and endpoints 0 and 10. Further, ranges relating to chemical substituents, such as, for example, "C₁To C₅Diol "is intended to specifically include and disclose C₁、C₂、C₃、C₄And C₅A diol.

Notwithstanding that the numerical ranges and parameters setting forth the broad scope of the invention are approximations, the numerical values set forth in the specific examples are reported as precisely as possible. Any numerical value, however, inherently contains certain errors necessarily resulting from the standard deviation found in their respective testing measurements.

As used in the specification and the appended claims, the singular forms "a", "an", and "the" include plural referents unless the context clearly dictates otherwise. For example, reference to "polyester," "dicarboxylic acid," "residue," is synonymous with "at least one" or "one or more" polyester, dicarboxylic acid, or residue, and thus is intended to refer to a single or multiple of a polyester, dicarboxylic acid, or residue. Furthermore, references to a composition "comprising," "containing," "having," or "including," "an" ingredient or "a" polyester are intended to include other ingredients or other polyesters, respectively, in addition to the specifically identified ingredients or residues. Thus, the terms "comprising," "having," or "including" are intended to be synonymous and may be used interchangeably with the term "comprising" and mean that at least the recited compound, element, particle, or method step, etc., is present in a composition or article or method, but does not exclude the presence of other compounds, catalysts, materials, particles, method steps, etc., even if other such compounds, materials, particles, method steps, etc., have the same function as what is said, unless expressly excluded in the claims.

Furthermore, it should be understood that reference to one or more method steps does not preclude the presence of additional method steps before or after the total number of recited steps or intervening method steps between those steps expressly identified. Moreover, the alphabetical designation of method steps or components is a convenient means for identifying discrete activities or components, and the alphabetical designation may be arranged in any order unless otherwise indicated.

As used herein, the term "curable aliphatic polyester" is synonymous with the term "resin" and is intended to mean a thermosetting surface coating polymer prepared by polycondensation of one or more acid and hydroxyl components. The curable aliphatic polyesters of the present invention are thermosetting polymers and are suitable for use as resins for solvent-borne coatings, more specifically single coat applications. Such polyesters have low molecular weights, typically 500 to 10,000 daltons, and may not be suitable for making films, sheets, and other shaped bodies by extrusion, casting, blow molding, and other thermoforming processes commonly used for high molecular weight thermoplastic polymers. The polyester has reactive functional groups, typically hydroxyl or carboxyl groups, in order to subsequently react with the crosslinker in the coating formulation. The functional groups are controlled by having an excess of diol or acid (from the di-or tri-carboxylic acids) in the polyester resin composition. The desired crosslinking route will determine whether the polyester resin is hydroxyl-terminated or carboxylic acid-terminated. This concept is known to the person skilled in the art and is described, for example, in the following books: wicks, f.jones and s.pappas, second edition, p 246-257, willi, New York,1999 (Organic Coatings Science and Technology,2nd ed., p.246-257, by z.wicks, f.jones, and s.pappas, Wiley, New York,1999), the entire disclosure of which is incorporated herein by reference.

Typically, the acid component includes at least one dicarboxylic acid, and may optionally include monocarboxylic acids and polycarboxylic acids. For example, the curable aliphatic polyester may be prepared from an acid component comprising an aliphatic or cycloaliphatic dicarboxylic acid, such as, for example, adipic acid, or 1, 3-cyclohexanedicarboxylic acid, or a mixture of one or more aliphatic and cycloaliphatic acids. The hydroxyl component comprises a diol and a polyol. The diols may comprise one or more cycloaliphatic diols, such as, for example, 2,4, 4-tetramethyl-1, 3-cyclobutanediol, used alone or in combination with one or more linear or branched aliphatic diols, such as, for example, neopentyl glycol. Catalysts may be used to accelerate the rate of the polycondensation reaction. Other examples of acid and hydroxyl components (other than TMCD) of the curable aliphatic polyester include those known in the art, including but not limited to those discussed below, and those known in various documents known in the art, such as, for example, in "Resins for Surface Coatings", volume III, pages 63-167, edited by P.K. T.Oldring and G.Hayward, SITA Technology, London, UK,1987 (Resins for Surface Coatings, Vol.III, p.63-167, ed.by P.K. T.Oldring and G.Hayward, SITA Technology, London, UK,1987), the disclosures of which are incorporated herein by reference.

As used herein with respect to the polymers of the present invention, the term "residue" refers to any organic structure introduced into the polymer by a polycondensation or ring opening reaction involving the corresponding monomer. It will also be understood by those of ordinary skill in the art that the relevant residues in the various curable polyesters of the present invention may be derived from the parent monomeric compound itself or any derivative of the parent compound. For example, the dicarboxylic acid residues mentioned in the polymers of the present invention may be derived from dicarboxylic acids or their associated acid halides, esters, salts, anhydrides or mixtures thereof. Thus, as used herein, the term "dicarboxylic acid" is intended to include dicarboxylic acids and any derivative of a dicarboxylic acid, including its associated acid halides, esters, half-esters, salts, half-salts, anhydrides, and mixtures thereof, which are used in a polycondensation reaction with a diol to produce a curable aliphatic polyester.

The term "aliphatic" is intended to have the ordinary meaning as understood by those of ordinary skill in the art, i.e., acyclic or cyclic, saturated or unsaturated carbon compounds, excluding benzenoid or other aromatic systems. As used herein, the term "cycloaliphatic" is intended to mean an aliphatic cyclic compound. As used herein, the term "aliphatic polyester" is understood to mean a polyester containing 90 mole% or more of aliphatic diacid or diol residues, based on the total moles of diacid or diol residues. Small amounts, for example less than 10 mole%, or less than 9 mole%, or less than 8 mole%, or less than 5 mole%, or less than 3 mole%, or less than 2 mole%, or less than 1 mole%, of aromatic dicarboxylic acid residues or aromatic diol residues may also be present in the curable aliphatic polyester. Desirably, the curable aliphatic polyester is substantially free of (i.e., has less than 1 mole percent of) aromatic diacid residues and/or aromatic diol residues.

The present invention relates to thermosetting automotive 1K varnishes comprising an aliphatic polyester resin comprising an aliphatic dibasic acid and 2,2,4, 4-tetraalkylcyclobutane-1, 3-diol (TACD), in particular 2,2,4, 4-tetramethyl-1, 3-cyclobutanediol (TMCD). The resin may be modified with various aliphatic diacids, diols, and polyols. We have found that aliphatic polyesters exhibit a combination of scratch resistance and hardness. Number average molecular weight (M) of aliphatic polyester resin_n) From about 500 to 10,000, preferably from about 750 to 5,000, preferably from about 1,000 to 3,500; glass transition temperature (T) of aliphatic polyester resin_g) From about-50 ℃ to 35 ℃, preferably from about-40 ℃ to 30 ℃, preferably from about-30 ℃ to 20 ℃; aliphatic polyesterThe hydroxyl group of the ester resin is from about 50mg KOH/g resin to 500mg KOH/g resin, preferably from about 100mg KOH/g resin to 350mg KOH/g resin, preferably from about 150mg KOH/g resin to 250mg KOH/g resin; the acid value of the aliphatic polyester resin is about 0mg KOH/g resin to 100mg KOH/g resin, preferably about 1mg KOH/g resin to 50mg KOH/g resin, preferably about 5mg KOH/g resin to 15mg KOH/g resin.

In one example, the 1K varnish of the present invention consists of:

A. from about 2 to about 50 weight percent of the above curable aliphatic polyester resin comprising, based on the total weight of (A), (B) and (C):

i. diacid residues comprising at least 90 mole percent of the residues of at least one aliphatic diacid, 0-40 mole percent of the at least one aliphatic diacid being cycloaliphatic diacid, 60-100 mole percent being linear diacids having 4 to 12 carbons, based on the total moles of diacid residues;

diol residues comprising, based on the total moles of diol residues: a) 25 to 100 mole percent, based on the total moles of diol residues, of 2,2,4, 4-tetraalkylcyclobutane-1, 3-diol (TACD) residues, and b) 0 to 75 mole percent, based on the total moles of diol residues, of C₂-C₂₀A diol; and

from about 5 to about 80 mole%, based on the total moles of diol and polyol residues, of residues of at least one polyol selected from trimethylolpropane, pentaerythritol, trimethylolethane, erythritol, threitol, dipentaerythritol, sorbitol, and glycerol;

B. about 15 to about 85 weight percent of an acrylic copolymer of at least one ethylenically unsaturated monomer containing urethane and/or hydroxyl functional groups, based on the total weight of (A), (B) and (C);

C. about 10 to about 50 weight percent of at least one crosslinking agent comprising at least one compound reactive with carbamate and/or hydroxyl groups, based on the total weight of (a), (B), and (C); and

D. about 10 to 60 wt% of at least one non-aqueous solvent, based on the total weight of (A), (B), (C) and (D).

The 1K clear coat composition crosslinker (C) comprises at least one melamine compound selected from hexamethoxymethylmelamine, tetramethoxymethylbenzotriamine, tetramethoxymethylurea, mixed butoxy/methoxy substituted melamines, and the like.

In another aspect, the present invention also provides a curable coating composition further comprising one or more crosslinking catalysts. Useful catalysts may include p-toluenesulfonic acid, dodecylbenzenesulfonic acid, dinonylnaphthalenesulfonic acid, and dinonylnaphthalenedisulfonic acid. These catalysts may be amine-blocked or unblocked. The catalyst is useful in an amount of about 0.01 to 5 percent based on the total weight of resin solids.

The 1K varnish non-aqueous solvent (D) comprises benzene, xylene, mineral spirits, naphtha, toluene, acetone, methyl ethyl ketone, methyl n-amyl ketone, methyl isoamyl ketone, n-butyl acetate, isobutyl acetate, t-butyl acetate, n-propyl acetate, isopropyl acetate, ethyl acetate, methyl acetate, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, isobutanol, ethylene glycol monobutyl ether, propylene glycol n-butyl ether, propylene glycol methyl ether, propylene glycol monopropyl ether, dipropylene glycol methyl ether, diethylene glycol monobutyl ether, trimethylpentanediol monoisobutyrate, ethylene glycol monooctyl ether, diacetone alcohol, 2, 4-trimethyl-1, 3-pentanediol monoisobutyrate, or a combination thereof.

The 1K varnish may also optionally contain coating additives such as leveling agents, rheology agents, flow control agents, plasticizers, matting agents, pigment wetting and dispersing agents, crosslinking catalysts, pigments, dyes, uv absorbers, uv stabilizers, defoamers, foam inhibitors, anti-settling agents (anti-settling agents), anti-sagging or sag control agents, thickeners, anti-skinning agents, anti-flooding agents, anti-floating agents (anti-floating agents), and corrosion inhibitors, used alone or in combination.

TACD is a diol and may be represented by the following general structure:

wherein R is₁、R₂、R₃And R₄Each independently represents an alkyl group, such as a lower alkyl group, having: 1 to 8 carbon atoms, or 1 to 6 carbon atoms, or 1 to 5 carbon atoms, or 1 to 4 carbon atoms, or 1 to 3 carbon atoms, or 1 to 2 carbon atoms, or 1 carbon atom. The alkyl group may be linear, branched or a combination of linear and branched alkyl groups. Examples of TACDs include: 2,2,4, 4-tetramethylcyclobutane-1, 3-diol (TMCD), 2,4, 4-tetraethylcyclobutane-1, 3-diol, 2,4, 4-tetra-n-propylcyclobutane-1, 3-diol, 2,4, 4-tetra-n-butylcyclobutane-1, 3-diol, 2,4, 4-tetra-n-pentylcyclobutane-1, 3-diol, 2,4, 4-tetra-n-hexylcyclobutane-1, 3-diol, 2,4, 4-tetra-n-heptylcyclobutane-1, 3-diol, 2,4, 4-tetra-n-octylcyclobutane-1, 3-diol, 2-dimethyl-4, 4-diethylcyclobutane-1, 3-diol, 2-ethyl-2, 4, 4-trimethylcyclobutane-1, 3-diol, 2, 4-dimethyl-2, 4-diethyl-cyclobutane-1, 3-diol, 2, 4-dimethyl-2, 4-di-n-propylcyclobutane-1, 3-diol, 2, 4-n-dibutyl-2, 4-diethylcyclobutane-1, 3-diol, 2, 4-dimethyl-2, 4-diisobutylcyclobutane-1, 3-diol and 2, 4-diethyl-2, 4-diisopentylcyclobutane-1, 3-diol. TMCD is most preferred.

(ii) The diol in (A) has 2 hydroxyl groups and may be branched or straight-chain, saturated or unsaturated, aliphatic or cycloaliphatic C₂-C₂₀The hydroxyl group of the compound is a primary, secondary and/or tertiary hydroxyl group, desirably a primary hydroxyl group. Examples of the diol (b) include: 2, 2-dimethyl-1, 3-propanediol (neopentyl glycol), 1, 2-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol, 1, 4-cyclohexanedimethanol, 2, 4-trimethyl-1, 3-pentanediol, hydroxypivalic acid neopentyl glycol monoester (hydroxypivalyl hydroxypivalate), 2-methyl-1, 3-propanediol, 2-butyl-2-ethyl-1, 3-propanediol, 2-ethyl-2-isobutyl-1, 3-propanediol, 1, 3-butanediol, 1, 4-butanediol, 1, 5-pentanediol, 1, 6-hexanediol, 2,4, 4-tetramethyl-1, 6-hexanediol, 1, 10-decanediol, 1, 4-benzenedimethanol, Ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol, and 2, 2-bis (hydroxymethyl) propionic acid (dimethylolpropionic acid).

Desirably, the diol (ii) is 2, 2-dimethyl-1, 3-propanediol (neopentyl glycol), 1, 2-cyclohexanedimethanol, 1, 3-cyclohexanedimethanol, 1, 4-cyclohexanedimethanol, 2, 4-trimethyl-1, 3-pentanediol, hydroxypivalic acid neopentyl glycol monoester, 2-methyl-1, 3-propanediol, 2-butyl-2-ethyl-1, 3-propanediol, 1, 4-butanediol, and 1, 6-hexanediol, or a mixture thereof. Desirably, at least one of the diols is neopentyl glycol.

(iii) The polyhydric alcohol having 3 or more hydroxyl groups in it may be saturated or unsaturated, aliphatic or alicyclic C₂-C₂₀A compound, the hydroxyl groups are primary, secondary and/or tertiary hydroxyl groups, and desirably at least two of the hydroxyl groups are primary hydroxyl groups. Desirably, the polyol is a hydrocarbon and contains no atoms other than hydrogen, carbon, and oxygen. Examples of the polyhydric alcohol include: 1,1, 1-Trimethylolpropane (TMP), 1,1, 1-trimethylolethane, glycerol, pentaerythritol, erythritol, threitol, dipentaerythritol, sorbitol, mixtures thereof, and the like. Desirably, the polyol is TMP.

(i) The cycloaliphatic diacid of (1) is a cyclic aliphatic dicarboxylic acid compound, a diester derivative thereof, an anhydride thereof, or a combination thereof. Suitable cycloaliphatic diacid compounds include compounds having two carboxylic acid groups, their diester derivatives, and their anhydrides. The dicarboxylic acid compound may form an ester bond with a diol or polyol compound. For example, polyesters can be synthesized by using polyhydroxy compounds and derivatives of dicarboxylic acids such as, for example, the dimethyl or other dialkyl esters of diacids, or diacid chlorides or other diacid halides, or anhydrides.

Suitable cycloaliphatic diacids include, but are not limited to: 1, 4-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, hexahydrophthalic anhydride (HHPA), methylhexahydrophthalic anhydride, tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, 5-norbornene-2, 3-dicarboxylic acid, 2, 3-norbornane dicarboxylic anhydride and mixtures thereof. HHPA is the most desirable cycloaliphatic diacid.

(i) The non-cyclic aliphatic diacid of (1) is an open chain aliphatic dicarboxylic acid compound, a diester derivative thereof, an anhydride thereof, or a combination thereof. Examples of acyclic aliphatic diacids include succinic acid, glutaric acid, adipic acid, itaconic anhydride, itaconic acid, citraconic anhydride, citraconic acid, pimelic acid, suberic acid, dodecanedioic acid, sebacic acid, azelaic acid, and the like.

Number average molecular weight (M) of the curable polyester A of the present invention_n) May be 500-10,000, 750-5,000 or 1,000-3,500 g/mol. Weight average molecular weight (M) of the curable polyester of the present invention_w) May be 1,000-10,000, 1,500-6,000 or 2,000-4,000 g/mol. Molecular weight was determined by Gel Permeation Chromatography (GPC) using polystyrene equivalent molecular weight.

The stoichiometric calculation of The reaction of polyester resin and melamine is known to those skilled in The art and is described on page 20 of The Publication of Bayer Material Science, coating Chemistry, 2005, The Chemistry of Coatings, Technical Publication p.20 by Bayer Material Science, which is incorporated herein by reference. Theoretically, when one equivalent of melamine (-OR) reacts with one equivalent of hydroxyl (OH), i.e., when the ratio of (-OR) to OH is 1.0/1.0, the crosslinking between the polyester resin and melamine reaches the maximum molecular weight and the optimum characteristics with respect to the molecular weight.

Some examples of UV absorbers and UV light stabilizers are: substituted benzophenones, substituted benzotriazoles, hindered amines and hindered benzoates, andUV from Cytec Specialty Chemicals (Cytec Specialty Chemicals) toPurchased from Ciba Specialty Chemicals; diethyl 3-acetyl-4-hydroxy-benzyl-phosphonate, 4-dodecyloxy-2-hydroxybenzophenone and resorcinol monobenzoate.

The substrate on which the coating of the present invention may be applied may include any common substrate, for example: paper; polymer films, such as polyethylene or polypropylene; wood; metals, such as aluminum, steel or galvanized sheet; glass; a polyurethane elastomer; a substrate primed (painted); and so on. The coating composition may be applied to the substrate using techniques known in the art, such as by spraying, knife-down, roll coating, and the like, to form a dried coating on the substrate having a thickness of from about 0.1 to about 4 mils (1 mil to 25 μm), or from 0.5 to 3, or from 0.5 to 2, or from 0.5 to 1 mil. The coating may be cured as follows: at ambient temperature (room temperature), or heated to a temperature of about 120 ℃ to about 200 ℃, typically for a period of about 10 to about 90 minutes, and allowed to cool.

The coating compositions reported in the present invention are particularly suitable for clear coat applications for automotive OEMs (Original Equipment manufacturers). In the polyol/melamine technology, current commercial urethane technology has brought automotive topcoats (finishes) to the current leading scratch and mar resistance levels. The addition of the chemical components of TACD can greatly improve the scratch performance of the clear coat in automotive topcoats.

Examples of the invention

The present invention is illustrated in more detail by the specific examples given below. It is to be understood that these examples are illustrative embodiments and are not intended to limit the invention, but rather should be construed broadly within the scope and content of the appended claims. All parts and percentages in the examples are by weight unless otherwise indicated.

Polyester examples 1 to 4

The polyester resin compositions in table 1 were prepared as follows.

Polyester example 1

The resin was prepared using a solvent process in a two-liter autoclave equipped with a heating mantle, a mechanical stirrer, a thermocouple, a nitrogen blanket (1.0scfh), an oil-heated partial condenser (103 ℃ -105 ℃), a condensate trap and a water-cooled total condenser (15 ℃). TMP (half of the total), NPG, AD, triphenyl phosphite (0.05 wt% based on the total charge), catalyst (0.025 wt% based on the total charge) and xylene (2.5 wt% based on the total charge) were added to the kettle. Additional xylene was used to fill the trap. The kettle was heated to 150 ℃ over 125 minutes to form a homogeneous melt. Stirring was started (300 rpm). The reaction mixture was heated to 170 ℃ over 40 minutes. When half of the ester is obtainedWhen the water is digested, the remaining TMP is added. The reaction mixture was then heated to 220 ℃ over 2 hours and held until a final acid number of 4-8mg KOH/g resin was obtained. The resin was cooled to 190 ℃ and filtered through a medium mesh filter into a paint can. The measured resin characteristics were acid value 7, hydroxyl value 151, M_nIs 2528 and T_gIs-41 ℃.

Polyester example 2

The resin was prepared using a solvent process in a two-liter autoclave equipped with a heating mantle, mechanical stirrer, thermocouple, nitrogen blanket (1.0scfh), oil-heated partial condenser (103-105 ℃), condensate trap and water-cooled total condenser (15 ℃). TMP (half of the total), NPG, TMCD, AD, triphenyl phosphite (0.1 wt% based on the total charge), catalyst (0.025 wt% based on the total charge), and xylene (2.5 wt% based on the total charge) were added to the kettle. Additional xylene was used to fill the trap. The kettle was heated to 150 ℃ over 125 minutes to form a homogeneous melt. Stirring was started (300 rpm). The reaction mixture was heated to 170 ℃ over 40 minutes. When half of the esterified water was obtained, the remaining TMP was added. The reaction mixture was then heated to 220 ℃ over 2 hours and held until a final acid number of 4-8mg KOH/g resin was obtained. The resin was cooled to 190 ℃ and filtered through a medium mesh filter into a paint can. The measured resin characteristics were acid value 8, hydroxyl value 158, M_n2315 and T_gIs-31 ℃.

Polyester example 3

The resin was prepared using a solvent process in a two-liter autoclave equipped with a heating mantle, a mechanical stirrer, a thermocouple, a nitrogen blanket (1.0scfh), an oil-heated partial condenser (103 ℃ -105 ℃), a condensate trap and a water-cooled total condenser (15 ℃). TMP (half of the total), TMCD, AD, triphenyl phosphite (0.1 wt%, based on the total charge), catalyst (0.025 wt%, based on the total charge), and xylene (2.5 wt%, based on the total charge) were added to the kettle. Additional xylene was used to fill the trap. The kettle was heated to 150 ℃ over 125 minutes to form a homogeneous melt. Stirring was started (300 rpm). The reaction mixture was heated to 1 in 40 minutesAt 70 ℃. When half of the esterified water was obtained, the remaining TMP was added. The reaction mixture was then heated to 220 ℃ over 2 hours and held until a final acid number of 4-8mg KOH/g resin was obtained. The resin was cooled to 190 ℃ and filtered through a medium mesh filter into a paint can. The measured resin characteristics were acid value 8, hydroxyl value 155, M_nIs 2336 and T_gIs-20 ℃.

Polyester example 4

The resin was prepared using a solvent process in a two-liter autoclave equipped with a heating mantle, a mechanical stirrer, a thermocouple, a nitrogen blanket (1.0scfh), an oil-heated partial condenser (103 ℃ -105 ℃), a condensate trap and a water-cooled total condenser (15 ℃). HHPA, TMP (half of the total), TMCD, AD, triphenyl phosphite (0.1 wt% based on total charge), catalyst (0.05 wt% based on total charge), and xylene (2.5 wt% based on total charge) were added to the kettle. Additional xylene was used to fill the trap. The kettle was heated to 130 ℃ over 105 minutes to form a homogeneous melt. Stirring was started (300 rpm). The reaction mixture was heated to 170 ℃ by the reaction exotherm. The reaction mixture was then heated to 200 ℃ over 60 minutes and held until an acid number of less than or equal to 214mg KOH/g resin was obtained. The resin was then cooled to 185 ℃ where the NPG and residual TMP were added. The reaction mixture was then heated to 230 ℃ over 2 hours and held until a final acid number of 5-8mg KOH/g resin was obtained. The resin was cooled to 190 ℃ and filtered through a medium mesh filter into a paint can. The measured resin characteristics were acid value 8, hydroxyl value 144, M_nIs 2047 and T_gIs-16 ℃.

TABLE 1

Examples of polyester resins having different TMCD contents

Examples of the invention	PE example 1	PE example 2	PE example 3	PE example 4
					Total monomer mol%
NPG	34.00	16.53	0.00	21.01
					TMCD	0.00	16.53	32.13	15.21
TMP	19.33	20.48	21.62	17.40
					HHPA	0.00	0.00	0.00	14.84
AD	46.66	46.45	46.25	31.54
					Calculating constants
OHN	172	172	172	156
					fOH	4.00	4.00	4.00	3.62
OHEW	325.00	325.00	325.00	359
					Mn	1300	1300	1300	1300
AN	10	10	10	10

Varnish examples 1 to 4

Polyester examples 1-4 were formulated into 1K melamine crosslinked varnishes as shown in table 2. The clear coat is then sprayed directly onto the substrate previously coated with electrocoat [ electrocoat ], basecoat [ primer ] (or basecoat 1[ basecoat ]), and basecoat (basecoat 2). The varnish was flashed (flash) for 10 minutes at room temperature and then cured in a forced air oven at 140 ℃ for 30 minutes.

Kogani pendulum hardness [ c ] of test varnishpendulum hardness](ASTM D4366), Forward impact resistance (ASTM D2794), and Nano scratch resistance (Table 2). The nano-scratch test was performed using a Bruker Hysitron TI 980 nano in situ meter (Bruker Hysitron TI 980 triboinder).

The results show that the varnishes made of the polyester resins containing TMCD (CC examples 2-4) have a better combination of hardness, impact resistance and resistance to nano-scratches than CC example 1 without TMCD. PE example 1 used in CC example 1 represents a typical polyester used by those skilled in the art to improve scratch resistance. While improving scratch resistance, the resulting hardness is unacceptable.

TABLE 2

Examples of varnishes with varying levels of TMCD

In Table 2, BYK 331, BYK 306, and BYK 392 are coating system additives commercially available from Bick Chemicals, Inc. (BYK-Chemie GmbH). Nacure 5414 is a polymer-blocked sulfonate catalyst used with an amino crosslinking resin commercially available from King industries, Inc. of King industries, USA. Total 91760 is91760SS-53, a thermosetting hydroxylated acrylic copolymer useful in combination with amino resins, modified with a sag control agent commercially available from Zymoly (Allnex). BGA is butyl glycol acetate. PMA is phorbol 12-myristic acid 13-acetate. MAK is methyl-n-amyl ketone. S150 is a SOLVESSO 150 mixed solvent, commercially available from ExxonMobil Corporation (ExxonMobile Corporation). BA is n-butyl acetate. UVA 1130 is a TINUVIN 1130 UV absorber, commercially available from BASF. HALS 123 is TINUVIN 123, a Hindered Amine Light Stabilizer (HALS), commercially available from Pasteur.

Polyester examples 5 to 10

The polyester resin compositions in table 3 were prepared as follows.

Polyester example 5

The resin was prepared using a solvent process in a two-liter autoclave equipped with a heating mantle, a mechanical stirrer, a thermocouple, a nitrogen blanket (1.0scfh), an oil-heated partial condenser (103 ℃ -105 ℃), a condensate trap and a water-cooled total condenser (15 ℃). TMP (half of the total), NPG, adipic acid, triphenyl phosphite (0.05 wt% based on the total charge), catalyst (0.025 wt% based on the total charge), and xylene (2.5 wt% based on the total charge) were added to the kettle. Additional xylene was used to fill the trap. The kettle was heated to 150 ℃ over 125 minutes to form a homogeneous melt. Stirring was started (300 rpm). The reaction mixture was heated to 170 ℃ over 40 minutes. When half of the esterified water was obtained, the remaining TMP was added. The reaction mixture was then heated to 220 ℃ over 2 hours and held until a final acid number of 4-8mg KOH/g resin was obtained.The resin was cooled to 190 ℃ and filtered through a medium mesh filter into a paint can. The measured resin characteristics were acid value 8, hydroxyl value 177, M_n1694 and T_gIs-44 ℃.

Polyester example 6

The resin was prepared using a solvent process in a two-liter autoclave equipped with a heating mantle, a mechanical stirrer, a thermocouple, a nitrogen blanket (1.0scfh), an oil-heated partial condenser (103 ℃ -105 ℃), a condensate trap and a water-cooled total condenser (15 ℃). TMP (half of the total), TMCD, succinic acid, triphenyl phosphite (0.05 wt% based on the total charge), catalyst (0.025 wt% based on the total charge), and xylene (2.5 wt% based on the total charge) were added to the kettle. Additional xylene was used to fill the trap. The kettle was heated to 150 ℃ over 125 minutes to form a homogeneous melt. Stirring was started (300 rpm). The reaction mixture was heated to 170 ℃ over 40 minutes. When half of the esterified water was obtained, the remaining TMP was added. The reaction mixture was then heated to 220 ℃ over 2 hours and held until a final acid number of 4-8mg KOH/g resin was obtained. The resin was cooled to 190 ℃ and filtered through a medium mesh filter into a paint can. The measured resin characteristics were acid value 7, hydroxyl value 170, M_nIs 2072 and T_gThe temperature was 8 ℃.

Polyester example 7

The resin was prepared using a solvent process in a two-liter autoclave equipped with a heating mantle, a mechanical stirrer, a thermocouple, a nitrogen blanket (1.0scfh), an oil-heated partial condenser (103 ℃ -105 ℃), a condensate trap and a water-cooled total condenser (15 ℃). TMP (half of the total), TMCD, adipic acid, triphenyl phosphite (0.05 wt% based on the total charge), catalyst (0.025 wt% based on the total charge), and xylene (2.5 wt% based on the total charge) were added to the kettle. Additional xylene was used to fill the trap. The kettle was heated to 150 ℃ over 125 minutes to form a homogeneous melt. Stirring was started (300 rpm). The reaction mixture was heated to 170 ℃ over 40 minutes. When half of the esterified water was obtained, the remaining TMP was added. The reaction mixture was then heated to 220 ℃ over 2 hours and held until the maximum was obtainedThe final acid value is 4-8mg KOH/g resin. The resin was cooled to 190 ℃ and filtered through a medium mesh filter into a paint can. The measured resin characteristics were acid value 7, hydroxyl value 180, M_n2193 and T_gIs-23 ℃.

Polyester example 8

The resin was prepared using a solvent process in a two-liter autoclave equipped with a heating mantle, a mechanical stirrer, a thermocouple, a nitrogen blanket (1.0scfh), an oil-heated partial condenser (103 ℃ -105 ℃), a condensate trap and a water-cooled total condenser (15 ℃). TMP (half of the total), TMCD, 1, 4-cyclohexanedicarboxylic acid, triphenyl phosphite (0.05 wt%, based on the total charge), catalyst (0.025 wt%, based on the total charge), and xylene (2.5 wt%, based on the total charge) were added to the kettle. Additional xylene was used to fill the trap. The kettle was heated to 150 ℃ over 125 minutes to form a homogeneous melt. Stirring was started (300 rpm). The reaction mixture was heated to 170 ℃ over 40 minutes. When half of the esterified water was obtained, the remaining TMP was added. The reaction mixture was then heated to 220 ℃ over 2 hours and held until a final acid number of 4-8mg KOH/g resin was obtained. The resin was cooled to 190 ℃ and filtered through a medium mesh filter into a paint can. The measured resin characteristics were acid value 6, hydroxyl value 186, M_n2074 and T_g 32℃。

Polyester example 9

The resin was prepared using a solvent process in a two-liter autoclave equipped with a heating mantle, a mechanical stirrer, a thermocouple, a nitrogen blanket (1.0scfh), an oil-heated partial condenser (103 ℃ -105 ℃), a condensate trap and a water-cooled total condenser (15 ℃). TMP (half of the total), TMCD, azelaic acid, triphenyl phosphite (0.05 wt% based on the total charge), catalyst (0.025 wt% based on the total charge), and xylene (2.5 wt% based on the total charge) were added to the kettle. Additional xylene was used to fill the trap. The kettle was heated to 150 ℃ over 125 minutes to form a homogeneous melt. Stirring was started (300 rpm). The reaction mixture was heated to 170 ℃ over 40 minutes. When half of the esterified water was obtained, the remaining TMP was added. The reaction mixture was then allowed to stand for 2 hoursHeated to 220 ℃ and held until a final acid number of 4-8mg KOH/g resin is obtained. The resin was cooled to 190 ℃ and filtered through a medium mesh filter into a paint can. The measured resin characteristics were acid value 6, hydroxyl value 177, and M_nIs 1684 and T_gIs-37 ℃.

Polyester example 10

The resin was prepared using a solvent process in a two-liter autoclave equipped with a heating mantle, a mechanical stirrer, a thermocouple, a nitrogen blanket (1.0scfh), an oil-heated partial condenser (103 ℃ -105 ℃), a condensate trap and a water-cooled total condenser (15 ℃). TMP (half of the total), TMCD, dodecanedioic acid, triphenyl phosphite (0.05 wt% based on the total charge), catalyst (0.025 wt% based on the total charge) and xylene (2.5 wt% based on the total charge) are added to the kettle. Additional xylene was used to fill the trap. The kettle was heated to 150 ℃ over 125 minutes to form a homogeneous melt. Stirring was started (300 rpm). The reaction mixture was heated to 170 ℃ over 40 minutes. When half of the esterified water was obtained, the remaining TMP was added. The reaction mixture was then heated to 220 ℃ over 2 hours and held until a final acid number of 4-8mg KOH/g resin was obtained. The resin was cooled to 190 ℃ and filtered through a medium mesh filter into a paint can. The measured resin characteristics were acid value 5, hydroxyl value 176, M_nIs 2690 and T_gIs-41 ℃.

TABLE 3

Examples of polyester resins with different diacid content

Varnish examples 5 to 10

Polyesters examples 5-10 were formulated into 1K melamine crosslinked varnishes as shown in table 4. The clear coat is then sprayed directly onto the substrate previously coated with the electrocoat, basecoat (or basecoat 1), and basecoat (basecoat 2). The varnish was flashed for 10 minutes at room temperature and then cured for 30 minutes in a forced air oven at 140 ℃.

The varnishes were tested for Cogner pendulum hardness (ASTM D4366) and nano scratch resistance (Table 4). The nano-scratch test was performed using a Bruker Hysitron TI 980 nm in situ meter.

The results show that the varnishes made of TMCD-containing polyester resins (CC examples 6-10) have a better combination of hardness and resistance to nano-scratches than CC example 5 without TMCD. PE example 5 used in CC example 5 represents a typical polyester used by those skilled in the art to improve scratch resistance. While improving scratch resistance, the resulting hardness is unacceptable. Further, linear aliphatic acids (C) of different carbon chain lengths may be used₄To C₁₂) In combination with TMCD to balance hardness and nano scratch resistance as desired.

TABLE 4

Examples of varnishes with different diacid contents

In table 4, BYK 331, BYK 306, and BYK 392 are coating system additives commercially available from BYK chemical limited. Nacure 5414 is a polymer-blocked sulfonate catalyst used with amino cross-linking resins commercially available from King industries, USA. Total 91760 is91760SS-53, a thermosetting hydroxylated acrylic copolymer useful in combination with amino resins modified with a sag control agent commercially available from Zhanxin corporation. BGA is butyl glycol acetate. PMA is phorbol 12-myristic acid 13-acetate. MAK is methyl-n-amyl ketone. S150 is a SOLVESSO 150 mixed solvent, commercially available from Exxon Mobil, Inc. BA is n-butyl acetate. UVA 1130 is a TINUVIN 1130 UV absorber, commercially available from Pasteur. HALS 123 is TINUVIN 123 and is a Hindered Amine Light Stabilizer (HALS) commercially available from BASF.

It is further contemplated that these TMCD-containing polyester resins may be blended with acrylic resins to improve the scratch resistance of the varnish while maintaining the beneficial performance attributes imparted by the acrylic resins. The acrylic resin may be hydroxyl functional or carbamate functional, as desired.

Having described the invention in detail, those skilled in the art will appreciate that modifications may be made to the various aspects of the invention without departing from the scope and spirit of the invention disclosed and described herein. It is therefore intended that the scope of the invention be limited not by the specific examples shown and described, but rather by the claims appended hereto and their equivalents. Further, all patents, patent applications, publications, and references mentioned herein are incorporated by reference in their entirety for any disclosure pertinent to the practice of this invention.