阅读说明：本技术 一种改性水性聚酯共聚物及其制备方法 (Modified water-based polyester copolymer and preparation method thereof ) 是由 陆均杰 李勇 顾宇昕 谢静 刘亮 赵蓉 于 2019-10-30 设计创作，主要内容包括：本发明属于聚酯树脂领域,公开了一种改性水性聚酯共聚物,由饱和聚酯预聚物、不饱和酯和多元酸反应得到；所述不饱和酯为甲基丙烯酸缩水甘油酯与丙烯酸酯类组成的混合物；所述多元酸至少包含一种脂环族二元酸；所述改性水性聚酯共聚物的端位的羧基,来自于脂环族多元酸的残基,其含量在改性水性聚酯共聚物的端羧基摩尔含量中不低于30％。本发明制备的改性水性聚酯共聚物中保持有合适的醚键与空间位阻型基团比例,并形成相间式分布,可显著改善高分子量聚酯的加工性、水分散性、稳定性和耐沸水性。(The invention belongs to the field of polyester resin, and discloses a modified waterborne polyester copolymer which is obtained by reacting a saturated polyester prepolymer, unsaturated ester and polybasic acid; the unsaturated ester is a mixture of glycidyl methacrylate and acrylate; the polybasic acid comprises at least one alicyclic dibasic acid; the carboxyl at the terminal position of the modified waterborne polyester copolymer is derived from the residue of alicyclic polybasic acid, and the content of the carboxyl is not less than 30 percent of the mol content of the terminal carboxyl of the modified waterborne polyester copolymer. The modified water-based polyester copolymer prepared by the invention has proper ether bond and steric hindrance group proportion, and is distributed in an interphase mode, so that the processability, water dispersibility, stability and boiling water resistance of high molecular weight polyester can be obviously improved.)

1. A modified waterborne polyester copolymer characterized by: obtained by the reaction of saturated polyester prepolymer, unsaturated ester and polybasic acid; the unsaturated ester is a mixture of glycidyl methacrylate and acrylate; the polybasic acid comprises at least one alicyclic dibasic acid; the carboxyl at the terminal position of the modified waterborne polyester copolymer is derived from the residue of alicyclic polybasic acid, and the content of the carboxyl is not less than 30 percent of the mol content of the terminal carboxyl of the modified waterborne polyester copolymer.

2. The modified aqueous polyester copolymer of claim 1, wherein: the acrylate is at least one of cyclohexyl methacrylate, 4-tert-butyl cyclohexyl acrylate, isobornyl methacrylate and 3-isobornyl cyclohexyl acrylate.

3. The modified aqueous polyester copolymer according to claim 1 or 2, characterized in that: the glass transition temperature of the saturated polyester prepolymer is not more than 0 ℃.

4. The modified aqueous polyester copolymer according to claim 1 or 2, characterized in that: the modified waterborne polyester copolymer has the number average molecular weight of 10000-30000 daltons, the glass transition temperature of-50-10 ℃, the hydroxyl value of 5-50 mgKOH/g and the acid value of 5-40 mgKOH/g.

5. A method for preparing the modified aqueous polyester copolymer according to any one of claims 1 to 4, wherein the modified aqueous polyester copolymer comprises: the method comprises the following steps:

(1) mixing polyalcohol, polybasic acid, a branched monomer and an esterification catalyst, and reacting for 1-3 h at 210-220 ℃ to obtain a saturated polyester prepolymer;

(2) cooling to 120-160 ℃, adding a diluent to adjust the viscosity of the system, adding glycidyl methacrylate and an alkaline catalyst, and carrying out heat preservation reaction for 1-2 hours;

(3) cooling to 80-140 ℃, dropwise adding acrylic esters and part of initiator to perform heat preservation reaction, and then adding the rest of initiator;

(4) adding polybasic acid, heating and carrying out heat preservation reaction to obtain the modified waterborne polyester copolymer.

6. The method of claim 5, wherein: the polyhydric alcohol in the step (1) is selected from one or more of ethoxylated bisphenol A, propoxylated bisphenol A, 2-methyl-1, 3-propylene glycol, diethylene glycol and dipropylene glycol; the polybasic acid in the step (1) is selected from one or more of 1, 2-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, 1-cyclobutyldicarboxylic acid, adipic acid, suberic acid and sebacic acid; the branched monomer in the step (1) is selected from one or more of trimethylolpropane, trimethylolethane, neopentyl glycol diglycidyl ether, butanediol diglycidyl ether, ethylene glycol diglycidyl ether, hexanediol diglycidyl ether and cyclohexanediol diglycidyl ether.

7. The method of claim 5, wherein: the diluent in the step (2) is one or more selected from dimethyl benzene, toluene, propylene glycol methyl ether acetate, ethylene glycol monobutyl ether, ethylene glycol tert-butyl ether, diethylene glycol butyl ether, dipropylene glycol butyl ether, propylene glycol methyl ether and dipropylene glycol methyl ether.

8. The method of claim 5, wherein: the esterification catalyst in the step (1) is one or more selected from antimony trioxide, antimony acetate, ethylene glycol antimony, monobutyl tin oxide, butyltin triisooctoate and dibutyltin dilaurate; the alkaline catalyst in the step (2) is one or more selected from tetraethylammonium bromide, tetrabutylammonium bromide, triphenylphosphine, dimethylbenzylamine and an organic phosphine/bromine complex.

9. The method of claim 5, wherein: the initiator in the step (3) is one or more selected from dicumyl peroxide, di-tert-butyl peroxide, tert-butyl peroxybenzoate, 1-bis (tert-amyl peroxy) cyclohexane and di-tert-amyl peroxide.

10. An aqueous coating characterized by: comprises the following components: the modified water-based polyester copolymer as claimed in any one of claims 1 to 4, a crosslinking agent, an auxiliary agent, a pigment filler and a catalyst.

Technical Field

The invention relates to the field of polyester resin, in particular to a modified waterborne polyester copolymer and a preparation method thereof.

Background

The polyester resin has the advantages of high fullness, good adhesive force, good processing performance and mechanical performance and the like, can be used as a general main film forming material in a thermosetting water-based paint composition, can also be suitable for special application fields such as sealing adhesive, fiber treatment, film and medium coating and the like, and has wide application prospect.

The high molecular weight polyester copolymer has outstanding advantages in post-processing property and adhesive force, but the water dispersibility and stability are not ideal, the hardness of a coating is low, the scratch resistance is poor, and the further wide application of the coating in water-based paint is influenced. In addition, the balance of water dispersibility and boiling water resistance of the water-based polyester is also one of the technical difficulties in the field at present. The acrylic resin with the characteristics of excellent coating hardness, scratch resistance, stain resistance and the like can improve the comprehensive performance of the coating composition of the polyester main body, but the acrylic resin and the polyester resin are directly blended in the water-based paint, so that the system compatibility, the stability and the post-processing performance are obviously reduced, and the coating extinction and other series problems are caused.

Therefore, there is a need to develop a water-dispersible polyester copolymer having high boiling water resistance, high adhesion and good processability.

Disclosure of Invention

The invention aims to provide a modified water-based polyester copolymer which has the advantages of water dispersibility, boiling water resistance, strong adhesive force and good processability.

In order to achieve the purpose, the invention adopts the following technical scheme:

a modified water-based polyester copolymer is obtained by the reaction of saturated polyester prepolymer, unsaturated ester and polybasic acid; the unsaturated ester is a mixture of glycidyl methacrylate and acrylate; the polybasic acid comprises at least one alicyclic dibasic acid; the carboxyl at the terminal position of the modified waterborne polyester copolymer is derived from the residue of alicyclic polybasic acid, and the content of the carboxyl is not less than 30 percent of the mol content of the terminal carboxyl of the modified waterborne polyester copolymer.

Preferably, the acrylate is at least one of cyclohexyl methacrylate, 4-tert-butylcyclohexyl acrylate, isobornyl methacrylate and 3-isobornyl cyclohexyl acrylate.

Preferably, the glass transition temperature of the saturated polyester prepolymer is not more than 0 ℃.

Preferably, the modified waterborne polyester copolymer has the number average molecular weight of 10000-30000 daltons, the glass transition temperature of-50-10 ℃, the hydroxyl value of 5-50 mgKOH/g and the acid value of 5-40 mgKOH/g.

Preferably, the number average molecular weight is 12000-30000 daltons. More preferably, the number average molecular weight is 15000 to 30000 daltons.

Preferably, the glass transition temperature is in the range of-50 ℃ to-5 ℃. More preferably, the glass transition temperature is from-50 ℃ to-10 ℃.

A preparation method of a modified water-based polyester copolymer comprises the following steps:

(1) mixing polyalcohol, polybasic acid, a branched monomer and an esterification catalyst, and reacting for 1-3 h at 210-220 ℃ to obtain a saturated polyester prepolymer;

(2) cooling to 120-160 ℃, adding a diluent to adjust the viscosity of the system, adding glycidyl methacrylate and an alkaline catalyst, and carrying out heat preservation reaction for 1-2 hours;

(3) cooling to 80-140 ℃, dropwise adding acrylic esters and part of initiator to perform heat preservation reaction, and then adding the rest of initiator;

(4) adding polybasic acid, heating and carrying out heat preservation reaction to obtain the modified waterborne polyester copolymer.

Preferably, the polyol in step (1) is one or more selected from ethoxylated bisphenol a, propoxylated bisphenol a, 2-methyl-1, 3-propanediol, diethylene glycol and dipropylene glycol. More preferably, the polyol is selected from one or both of ethoxylated bisphenol a and propoxylated bisphenol a.

Preferably, the polybasic acid in the step (1) is one or more selected from 1, 2-cyclohexanedicarboxylic acid, 1, 3-cyclohexanedicarboxylic acid, 1, 4-cyclohexanedicarboxylic acid, 1-cyclobutyldicarboxylic acid, adipic acid, suberic acid and sebacic acid.

Preferably, the branched monomer in step (1) is selected from one or more of trimethylolpropane, trimethylolethane, neopentyl glycol diglycidyl ether, butanediol diglycidyl ether, ethylene glycol diglycidyl ether, hexanediol diglycidyl ether and cyclohexanediol diglycidyl ether.

Preferably, the diluent in the step (2) is one or more selected from the group consisting of xylene, toluene, propylene glycol methyl ether acetate (PMA), ethylene glycol monobutyl ether (BCS), ethylene glycol tert-butyl Ether (ETB), diethylene glycol butyl ether (BDG), dipropylene glycol butyl ether (DPnB), propylene glycol methyl ether (PM) and dipropylene glycol methyl ether (DPM).

Preferably, the esterification catalyst in step (1) is one or more selected from antimony trioxide, antimony acetate, ethylene glycol antimony, monobutyl tin oxide, butyl tin triisooctoate and dibutyl tin dilaurate.

Preferably, the basic catalyst in step (2) is one or more selected from tetraethylammonium bromide, tetrabutylammonium bromide, triphenylphosphine, dimethylbenzylamine and an organic phosphine/bromine complex.

Preferably, the incubation time in step (3) is 2-6 hours.

Preferably, the acrylate in the step (3) is one or more selected from cyclohexyl methacrylate, 4-tert-butylcyclohexyl acrylate, isobornyl methacrylate and isobornyl acrylate.

Preferably, the initiator in the step (3) is one or more selected from dicumyl peroxide, di-tert-butyl peroxide, tert-butyl peroxybenzoate, 1-bis (tert-amylperoxy) cyclohexane and di-tert-amylperoxide.

An aqueous coating comprising the following components: modified water-based polyester copolymer, cross-linking agent, auxiliary agent, pigment and filler and catalyst.

Preferably, the crosslinking agent is selected from one or more of melamine compound, isocyanate compound and epoxy group-containing compound.

More preferably, the melamine compound is selected from one or more of hexamethoxymethylmelamine, tetramethoxymethylbenzotriamine and melamine partially substituted by butoxy/methoxy; the isocyanate compound is one or more selected from diphenylmethane diisocyanate, isophorone diisocyanate, hexamethylene diisocyanate and dicyclohexylmethane diisocyanate.

The invention has the advantages that:

the modified water-based polyester copolymer prepared by the invention has proper ether bond and steric hindrance group proportion, and is distributed in an interphase mode, so that the processability, water dispersibility, stability and boiling water resistance of high molecular weight polyester can be obviously improved; meanwhile, glycidyl methacrylate and acrylic monomers with special steric hindrance structures are introduced into the polyester chain segment, so that the comprehensive performances of the coating such as hardness, scratch resistance, stain resistance, chemical resistance and the like can be remarkably improved, and the excellent stability and compatibility of a modified polyester system are realized.

Detailed Description

For a further understanding of the invention, preferred embodiments of the invention are described below with reference to the examples to further illustrate the features and advantages of the invention, and any changes or modifications that do not depart from the gist of the invention will be understood by those skilled in the art to which the invention pertains, the scope of which is defined by the scope of the appended claims.