Aliphatic polyester coating compositions containing tetramethyl cyclobutanediol

Abstract

Disclosed are aliphatic polyester resins containing specific molar quantities of 2,2,4,4-tetramethyl-1,3-cyclobutanediol, and solvent borne, thermosetting monocoating compositions prepared therefrom. The aliphatic polyesters exhibit good hardness and flexibility when formulated into thermosetting coatings compositions.

We claim: 
     
         1 . A curable, aliphatic polyester comprising residues of:
 i. a hydroxyl component, said hydroxyl component comprising the residues of:
 a. from 5 to 45 mole %, based on the total moles of (a) and (b), of 2,2,4,4-tetraalkylcyclobutane-1,3-diol (TACD); 
 b. from 55 to 95 mole % based on the total moles of (a) and (b), of a diol other than TACD; and 
 c. from 3 to 35 mole %, based on the total moles of (a), (b) and (c), of a polyol; 
   ii. a diacid component, said diacid component comprising the residues of:
 d. from 60 to 90 mole %, based on the total moles of the diacids of an alicyclic diacid; and 
 e. from 10 to 40 mole %, based on the total moles of the diacids an acyclic aliphatic diacid; 
   wherein the curable polyester contains diacid residues in an amount of at least 90 mole % of aliphatic diacid residues, based on the total moles of all diacid residues in the curable polyester, and, wherein the curable polyester has a hydroxyl number of 50 to 450 mgKOH/g of polyester, an acid number of 0 to 80 mgKOH/g, and a number average molecular weight of 300 to 10,000 g/mole of polyester.   
     
     
         2 . The curable, aliphatic polyester of  claim 1 , wherein said diacid is essentially free of aromatic diacid residues. 
     
     
         3 . The curable polyester of  claim 1 , wherein TACD comprises 2,2,4,4-tetramethyl-1,3-cyclobutanediol. 
     
     
         4 . The curable polyester of  claim 1 , wherein the diol (b) is selected from the group consisting of 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4-trimethyl-1,3-pentanediol, hydroxypivalyl hydroxypivalate, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and mixtures thereof. 
     
     
         5 . The curable polyester of  claim 4 , wherein at least 15 mole % of the diol (b) residues is neopentyl glycol based on the total moles of diol (b). 
     
     
         6 . The curable polyester of  claim 1 , wherein the molar ratio of (b):(a) is from 1.5:1 to 2.0:1. 
     
     
         7 . The curable polyester of  claim 1 , wherein the polyol (c) is one or more selected from the group consisting of 1,1,1-trimethylolpropane (TMP), 1,1,1-trimethylolethane, glycerin, and pentaerythritol. 
     
     
         8 . The curable polyester of  claim 1 , wherein the alicyclic diacid (d) is selected from the group consisting of hexahydrophthalic anhydride (HHPA), tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic acid, 2,3-norbornanedicarboxylic acid, 2,3-norbornanedicarboxylic acid anhydride, and mixtures thereof. 
     
     
         9 . The curable polyester of  claim 1 , wherein the alicyclic diacid (d) comprises hexahydrophthalic anhydride. 
     
     
         10 . The curable polyester of  claim 1 , wherein the acyclic aliphatic diacid (e) is selected from the group consisting of adipic acid, maleic anhydride, maleic acid, fumaric acid, itaconic anhydride, succinic acid, succinic anhydride, glutaric acid, itaconic acid, citraconic anhydride, citraconic acid, dodecanedioic acid, sebacic acid, azelaic acid, and mixtures thereof. 
     
     
         11 . The curable polyester of  claim 1 , wherein the acyclic aliphatic diacid (e) comprises adipic acid. 
     
     
         12 . The curable polyester of  claim 1 , wherein (a) comprises from 30 to 40 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and (b) comprises from 60 to 70 mole % of a diol selected from the group consisting of 2,2-dimethyl-1,3-propanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4-trimethyl-1,3-pentanediol, hydroxypivalyl hydroxypivalate, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and mixtures thereof, wherein the mole % is based on the total moles of (a) and (b). 
     
     
         13 . The curable polyester of  claim 1 , wherein the diacid component comprise 60 to 70 mole % of the residues of at least one alicyclic diacid comprising an anhydride and 32 to 38 mole % residues of an acyclic alphatic diacid comprising adipic acid, succinic anhydride, succinic acid, glutaric acid and mixtures thereof, and, wherein the curable polyester is obtained with no or less than 3 mole % acids having a carboxylic acid functionality of greater than 2 based on the total moles of all carboxylic acid compound residues. 
     
     
         14 . The curable polyester of  claim 1  comprising 20 to 30 mole % residues of (c), based on the total moles of the diols and polyol, (a), (b), and (c). 
     
     
         15 . The curable polyester of  claim 1  comprising from 62 to 67 mole % residues of (d), based on based on the total moles of the diacids (d) and (e). 
     
     
         16 . The curable polyester of  claim 1 , wherein the acid number is less than 20 mgKOH/g of polyester. 
     
     
         17 . The curable polyester of  claim 1 , wherein the hydroxyl number is from 100 to 200 mgKOH/g of polyester. 
     
     
         18 . A thermosetting coating solution comprising:
 A. 50 to 90 weight percent, based on the total weight of (A) and (B) of at least one curable, aliphatic polyester, comprising residues of:
 i. hydroxyl component, said hydroxyl component comprising the residues of:
 a. from 5 to 45 mole %, based on the total moles of (a) and (b), of 2,2,4,4-tetraalkylcyclobutane-1,3-diol (TACD); 
 b. from 55 to 95 mole % based on the total moles of (a) and (b), of a diol other than TACD; and 
 c. from 3 to 35 mole %, based on the total moles of (a), (b) and (c), of a polyol; 
 
 ii. a diacid component, said diacid component comprising the residues of:
 d. from 60 to 90 mole %, based on the total moles of the diacids (d) and (e), of an alicyclic diacid; and 
 e. from 10 to 40 mole %, based on the total moles of the diacids (d) and (e), of an acyclic aliphatic diacid; 
 
   wherein the curable polyester contains diacid residues in an amount of at least 90 mole % of aliphatic diacid residues, based on the total moles of all diacid residues in the curable polyester, and, wherein the curable polyester has a hydroxyl number of 50 to 450 mgKOH/g of polyester, an acid number of 0 to 80 mgKOH/g, and a number average molecular weight of 300 to 10,000 g/mole of polyester; and   B. from 10 to 50 weight percent, based on the total weight of the solution, of a solvent other than water.   
     
     
         19 . The thermosetting coating solution of  claim 18 , wherein said solution has less than 1 weight % of undissolved solids. 
     
     
         20 . The thermosetting coating solution of  claim 18 , wherein said diacid is essentially free of aromatic diacid residues. 
     
     
         21 . The thermosetting coating solution of  claim 18 , wherein said TACD comprises 2,2,4,4-tetramethyl-1,3-cyclobutanediol. 
     
     
         22 . The curable polyester of  claim 18 , wherein at least 15 mole % of the diol (b) residues is neopentyl glycol based on the total moles of diol (b). 
     
     
         23 . The thermosetting coating solution of  claim 18 , wherein the molar ratio of (b):(a) is from 1.5:1 to 2.0:1. 
     
     
         24 . The thermosetting coating solution of  claim 18 , wherein the polyol (c) is one or more selected from the group consisting of 1,1,1-trimethylolpropane (TMP), 1,1,1-trimethylolethane, glycerin, and pentaerythritol. 
     
     
         25 . The thermosetting coating solution of  claim 18 , wherein the alicyclic diacid (d) comprises hexahydrophthalic anhydride. 
     
     
         26 . The thermosetting coating solution of  claim 25 , wherein the acyclic aliphatic diacid (e) comprises adipic acid. 
     
     
         27 . The thermosetting coating solution of  claim 18 , wherein (a) comprises from 30 to 40 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and (b) comprises from 60 to 70 mole % of a diol selected from the group consisting of 2,2-dimethyl-1,3-propanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4-trimethyl-1,3-pentanediol, hydroxypivalyl hydroxypivalate, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and mixtures thereof, wherein the mole % is based on the total moles of (a) and (b). 
     
     
         28 . The thermosetting coating solution of  claim 18 , wherein the diacid residues comprises 60 to 70 mole % of the residues of at least one alicyclic diacid comprising an anhydride and 32 to 38 mole % residues of an acyclic alphatic diacid comprising adipic acid, succinic acid, glutaric acid and mixtures thereof. 
     
     
         29 . The thermosetting coating solution of  claim 18  comprising 20 to 30 mole % residues of (c), based on the total moles of the diols and polyol, (a), (b), and (c). 
     
     
         30 . The thermosetting coating solution of  claim 18  comprising from 62 to 67 mole % residues of (d), based on based on the total moles of the diacids (d) and (e). 
     
     
         31 . The thermosetting coating solution of  claim 18 , wherein the curable polyester has an acid number of less than 20 mgKOH/g of polyester. 
     
     
         32 . The thermosetting coating solution of  claim 18 , wherein the curable polyester has a hydroxyl number of 100 to 200 mgKOH/g of polyester and the acid number is from 5 to 15 mgKOH/g of polyester. 
     
     
         33 . The thermosetting coating solution of  claim 18 , wherein said solvent comprises less than 3 weight % water, based on the weight of the solution. 
     
     
         34 . The thermosetting coating solution of  claim 18 , wherein said solvent comprises xylene, methyl amyl ketone, n-butyl acetate, Aromatic 100, and/or Aromatic 150. 
     
     
         35 . A thermosetting monocoat coating composition comprising:
 A. 50 to 90 weight percent, based on the total weight of (A) and (C), of at least one curable, aliphatic polyester, comprising residues of:
 i. hydroxyl component, said hydroxyl component comprising the residues of:
 a. from 5 to 45 mole %, based on the total moles of (a) and (b), of 2,2,4,4-tetraalkylcyclobutane-1,3-diol (TACD); 
 b. from 55 to 95 mole % based on the total moles of (a) and (b), of a diol other than TACD; and 
 c. from 3 to 35 mole %, based on the total moles of (a), (b) and (c), of a polyol; 
 
 ii. a diacid component, said diacid component comprising the residues of:
 d. from 60 to 90 mole %, based on the total moles of the diacids (d) and (e), of an alicyclic diacid; and 
 e. from 10 to 40 mole %, based on the total moles of the diacids (d) and (e), of an acyclic aliphatic diacid; 
 
   wherein the curable polyester contains diacid residues in an amount of at least 90 mole % of aliphatic diacid residues, based on the total moles of all diacid residues in the curable polyester, and, wherein the curable polyester has a hydroxyl number of 50 to 450 mgKOH/g of polyester, an acid number of 0 to 80 mgKOH/g, and a number average molecular weight of 300 to 10,000 g/mole of polyester; and   B. from 10 to 50 weight percent, based on the total weight of the coating composition, of a solvent other than water; and   C. from 10 to 50 weight percent, based on the total weight of (A) and (C), of a crosslinker comprising an aminoplast and/or isocyanate.   
     
     
         36 . The thermosetting monocoat coating composition of  claim 35 , wherein said diacid is essentially free of aromatic diacid residues. 
     
     
         37 . The thermosetting monocoat coating composition of  claim 35 , wherein said TACD comprises 2,2,4,4-tetramethyl-1,3-cyclobutanediol. 
     
     
         38 . The thermosetting monocoat coating composition of  claim 35 , wherein the alicyclic diacid (d) is selected from the group consisting of hexahydrophthalic anhydride (HHPA), tetrahydrophthalic anhydride, tetrachlorophthalic anhydride, 5-norbornene-2,3-dicarboxylic anhydride, 5-norbornene-2,3-dicarboxylic acid, 2,3-norbornanedicarboxylic acid, 2,3-norbornanedicarboxylic acid anhydride, and mixtures thereof. 
     
     
         39 . The thermosetting monocoat coating composition of  claim 35 , wherein the acyclic aliphatic diacid (e) is selected from the group consisting of adipic acid, maleic anhydride, maleic acid, fumaric acid, itaconic anhydride, itaconic acid, citraconic anhydride, citraconic acid, dodecanedioic acid, sebacic acid, azelaic acid, and mixtures thereof. 
     
     
         40 . The thermosetting monocoat coating composition of  claim 35 , wherein (a) comprises from 30 to 40 mole % 2,2,4,4-tetramethyl-1,3-cyclobutanediol and (b) comprises from 60 to 70 mole % of a diol selected from the group consisting of 2,2-dimethyl-1,3-propanediol, 1,2-cyclohexanedimethanol, 1,3-cyclohexanedimethanol, 1,4-cyclohexanedimethanol, 2,2,4-trimethyl-1,3-pentanediol, hydroxypivalyl hydroxypivalate, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,4-butanediol, 1,6-hexanediol and mixtures thereof, wherein the mole % is based on the total moles of (a) and (b). 
     
     
         41 . The thermosetting monocoat coating composition of  claim 35 , wherein the crosslinker (B) is an aminoplast selected from the group comprising hexamethoxymethylmelamine, tetramethoxymethylbenzo-guanamine, tetramethoxymethylurea, hexabutoxymethylmelamine, mixed butoxy/methoxy methylmelamines and mixtures thereof. 
     
     
         42 . The thermosetting monocoat coating composition of  claim 35 , wherein the crosslinker (C) comprises hexamethoxymethylmelamine. 
     
     
         43 . The thermosetting coating solution of  claim 35 , wherein said solvent comprises less than 3 weight % water, based on the weight of the solution. 
     
     
         44 . The thermosetting monocoat coating composition of  claim 35 , further comprising applying said coating to a substrate and applying heat for a predetermined time and temperature to produce a cured coating, wherein the cured coating has an impact resistance of greater than 35 as determined in accordance with ASTM 4366. 
     
     
         45 . The thermosetting monocoat coating composition of  claim 44 , wherein the cured coating has an impact resistance of from 60 to 200, as determined in accordance with ASTM 4366. 
     
     
         46 . The thermosetting monocoat coating composition of  claim 44 , wherein the cured coating has a gloss retention, based on SAE J2527, of greater than 85% after 2500 hours. 
     
     
         47 . The thermosetting monocoat coating composition of  claim 44 , wherein the cured coating has a gloss retention, based on SAE J2527, of greater than 85% after 4000 hours. 
     
     
         48 . A method for applying a thermosetting monocoat coating composition to a substrate comprising:
 I. providing a suitable substrate for coating;   II. providing a thermosetting monocoat coating composition comprising:
 A. 50 to 90 weight percent, based on the total weight of (A) and (C), of at least one curable, aliphatic polyester, comprising residues of:
 i. hydroxyl component, said hydroxyl component comprising the residues of:
 a. from 5 to 45 mole %, based on the total moles of (a) and (b), of 2,2,4,4-tetraalkylcyclobutane-1,3-diol (TACD); 
 b. from 55 to 95 mole % based on the total moles of (a) and (b), of a diol other than TACD; and 
 c. from 3 to 35 mole %, based on the total moles of (a), (b) and (c), of a polyol; 
 
 ii. a diacid component, said diacid component comprising the residues of:
 d. from 60 to 90 mole %, based on the total moles of the diacids (d) and (e), of an alicyclic diacid; and 
 e. from 10 to 40 mole %, based on the total moles of the diacids (d) and (e), of an acyclic aliphatic diacid; 
 
 
   wherein the curable polyester contains diacid residues in an amount of at least 90 mole % of aliphatic diacid residues, based on the total moles of all diacid residues in the curable polyester, and, wherein the curable polyester has a hydroxyl number of 50 to 450 mgKOH/g of polyester, an acid number of 0 to 80 mgKOH/g, and a number average molecular weight of 300 to 10,000 g/mole of polyester;
 B. from 10 to 50 weight percent, based on the total weight of the coating composition, of a solvent other than water; and 
 C. from 10 to 50 weight percent, based on the total weight of (A) and (C), of a crosslinker comprising an aminoplast and/or isocyanate; 
   III. applying said thermosetting monocoat coating composition to said substrate to produce a coated substrate; and   IV. applying heat to the coated substrate to a predetermined temperature and for a predetermined time to produce a cured coating.   
     
     
         49 . The method of  claim 48 , wherein said diacid is essentially free of aromatic diacid residues. 
     
     
         50 . The method of  claim 48 , wherein said TACD is 2,2,4,4-tetramethyl-1,3-cyclobutanediol. 
     
     
         51 . The method of  claim 48 , wherein said diacid contains, if any, 5 mole % or less aromatic dicarboxylic acids residues or aromatic diol residues based on the monocoat coating composition. 
     
     
         52 . The method of  claim 48 , wherein said the alicyclic diacid (d) comprises hexahydrophthalic anhydride (HHPA). 
     
     
         53 . The method of  claim 48 , wherein said polyester in said monocoat coating composition has an acid number of less than 20 mgKOH/g of polyester. 
     
     
         54 . The method of  claim 48 , wherein said polyester in said monocoat coating has a hydroxyl number of 100 to 200 mgKOH/g of polyester. 
     
     
         55 . The method of  claim 48 , wherein said cured coating has an impact resistance of greater than 35 as determined in accordance with ASTM 4366. 
     
     
         56 . The method of  claim 48 , wherein said cured coating has an impact resistance of from 60 to 200, as determined in accordance with ASTM 4366. 
     
     
         57 . The method of  claim 48 , wherein said cured coating has a gloss retention, based on ASTM D 6279, of greater than 70%. 
     
     
         58 . The method of  claim 48 , wherein said cured coating has a gloss retention, based on SAE J2527, of greater than 85% after 2000 hours. 
     
     
         59 . The method of  claim 48 , wherein said cured coating has a gloss retention, based on SAE J2527, of greater than 85% after 4000 hours. 
     
     
         60 . The method of  claim 48 , wherein said substrate is metal. 
     
     
         61 . The method of  claim 60 , wherein said metal substrate is at least one surface of an automobile. 
     
     
         62 . The method of  claim 48 , wherein said applying the thermosetting monocoat coating composition to the substrate step comprises brushing, spraying, and roll coating. 
     
     
         63 . The method of  claim 62 , comprising spraying, wherein said spraying comprises rotational bell spraying. 
     
     
         64 . The method of  claim 63 , wherein said heating step comprises heating said coated substrate to a temperature of from 60° C. to 200° C. for a period of from 5 seconds to 5 hours. 
     
     
         65 . The method of  claim 64 , wherein said period is from 10 minutes to 1 hour. 
     
     
         66 . The method of  claim 48 , wherein said solvent in said thermosetting monocoat coating comprises less than 3 weight % water, based on the weight of the solution.