High-toughness polyester resin as well as preparation method and application thereof

Abstract

The invention belongs to the technical field of coatings, and particularly relates to high-toughness polyester resin as well as a preparation method and application thereof. The high-toughness polyester resin is prepared from the following raw materials: first polyhydric alcohol, first polybasic acid and an acidolysis agent, the acidolysis agent is prepared from the following raw materials: polyamine, second polyol, polyisocyanate and second polyacid; the first polyol is the same as or different from the second polyol; the first polyacid and the second polyacid are the same or different. The acidolysis agent is prepared from the polyamine, the second polyol, the polyisocyanate, the second polybasic acid and the catalyst, so that the polyester resin has a polyurea / polyurethane structure, intramolecular hydrogen bonds are increased, the structural difference is increased, and the polyester resin has a good anti-aging effect. The polyester resin has excellent impact resistance, bending resistance, impact delay, bending delay, leveling property and easy extinction property after being cured into a film, the appearance is flat and smooth, and the problem that the extinction property, the mechanical property and the leveling property of a mixed powder coating cannot be considered at the same time can be solved.

Description

Technical Field

[0001] The invention belongs to the technical field of coatings, and particularly relates to a high-toughness polyester resin and a preparation method and application thereof. Background Art

[0002] Powder coatings have the characteristics of zero volatile organic compounds (VOC), simple preparation, efficient and recyclable spraying, and excellent coating performance. They are favored by people in the fields of building materials, home decoration, and industry. According to different usage scenarios, powder coatings can be divided into two categories: indoor hybrid (polyester / epoxy) and outdoor weather-resistant (polyester / triglycidyl isocyanurate (TGIC) and polyester / hydroxyalkylamide (HAA)). Among them, hybrid powder coatings are mainly used for coating in the fields of home appliances and home decoration. In order to improve production and transportation efficiency, most metal anti-theft doors, lockers, aluminum ceilings, etc. are now mostly coated with a secondary molding process of first coating and then processing and molding. The powder coating is first sprayed on the metal sheet or various anti-theft door panels to solidify into a film, and then stamping, folding, rolling, edge sealing and other processes are performed. This requires the corresponding powder coating to have excellent impact resistance and bending resistance, but the existing hybrid powder coatings generally have the problem of insufficient toughness, which is difficult to meet the high requirements of the secondary molding process for toughness.

[0003] Some studies have introduced high molecular weight bisphenol A epoxy resin into polyester, and the powder coating prepared by it has excellent delayed impact performance, but only high gloss coating can be prepared, and the curing agent is TGIC and HAA, which is not suitable for mixed curing system. Some studies have sprayed the phosphite coupling agent on the filler after atomization for surface modification, which needs to be coordinated with the drying and dispersion process, otherwise the filler will easily agglomerate, which is not conducive to the dispersion and extrusion of the raw material, but its impact performance and bending performance are general, and the polyester resin is a conventional polyester resin. Some studies have synthesized polyester with a large molecular weight and narrow distribution, and has excellent cross-linking density after curing. By further optimizing the powder coating formula, a powder coating with good delayed mechanical properties was finally obtained, but this coating belongs to the TGIC system and is not suitable for mixed curing system. Some studies have synthesized modified polyester by crushing recycled polyethylene terephthalate (PET) and polyethylene naphthalate (PEN) plastics through transesterification and alcoholysis reactions with polyols. The sand-textured powder coating prepared from the polyester has good water resistance, UV resistance, and high-temperature storage stability, but it is not disclosed whether the powder coating has good bending performance, and the curing agent is HAA, which is not suitable for mixed curing systems. In short, the mixed powder coating prepared from the current polyester resin still cannot meet the high toughness requirements of the secondary processing molding process, and the matting, mechanical properties, and leveling properties cannot be taken into account at the same time.

[0004] Therefore, there is an urgent need to provide a polyester resin that is suitable for a hybrid powder coating system. The prepared coating has good impact resistance and bending performance, can meet the requirements of the secondary molding process for high toughness of the coating, and has good matting and leveling properties. Summary of the invention

[0005] The present invention aims to solve one or more technical problems existing in the above-mentioned prior art, and at least provide a beneficial choice or create conditions. Specifically, the present invention provides a high-toughness polyester resin, which is suitable for a hybrid powder coating system. The prepared coating has good impact resistance and bending performance, can meet the requirements of the secondary molding process for high toughness of the coating, and at the same time has good matting performance and leveling performance.

[0006] The inventive concept of the present invention is as follows: the raw materials for preparing the high-toughness polyester resin of the present invention include a first polyol, a first polyacid, and an acidolysis agent; the raw materials for preparing the acidolysis agent include a polyamine, a second polyol, a polyisocyanate, and a second polyacid; the first polyol is the same or different from the second polyol; the first polyacid is the same or different from the second polyacid. The acidolysis agent of the present invention is prepared by using polyamine, a second polyol, a polyisocyanate, and a second polyacid. The prepared acidolysis agent has a polyurea / polyurethane structure, increases intramolecular hydrogen bonds, increases structural differences, and makes the polyurea / polyurethane modified polyester resin have a suitable molecular weight, viscosity, glass transition temperature and reaction activity, so that the polyester resin has excellent impact resistance, bending resistance, leveling, and easy matting performance after being cured into a film, the coating gloss is below 10° and the appearance is flat and smooth, the delayed impact is greater than 90 days, and the delayed bending performance is greater than 30 days, which solves the problem that the matting, mechanical properties, and leveling properties of the hybrid powder coating cannot be taken into account.

[0007] Therefore, a first aspect of the present invention provides a polyester resin with high toughness.

[0008] Specifically, the raw materials for preparing the high-toughness polyester resin include a first polyol, a first polyacid, and an acidolysis agent;

[0009] The raw materials for preparing the acidolysis agent include polyamine, a second polyol, polyisocyanate, and a second polyacid;

[0010] The first polyol is the same as or different from the second polyol; the first polyacid is the same as or different from the second polyacid.

[0011] Preferably, the acid value of the polyester resin is 25-75 mgKOH / g, more preferably, the acid value of the polyester resin is 35-72 mgKOH / g, and even more preferably, the acid value of the polyester resin is 45-65 mgKOH / g.

[0012] Preferably, the viscosity of the polyester resin is 2500-7500 mPa·s, more preferably, the viscosity of the polyester resin is 3200-6500 mPa·s, and even more preferably, the viscosity of the polyester resin is 4000-5500 mPa·s.

[0013] Preferably, the first polyol includes at least one of ethylene glycol, 1.3-propylene glycol, 1.2-propylene glycol, 1.4-butylene glycol, neopentyl glycol, diethylene glycol, hexylene glycol, trimethylolpropane, ethyl butyl propanediol, 1.4-cyclohexanediol, and pentaerythritol.

[0014] Preferably, when the first polyol comprises two or more components at the same time, the components are mixed in an equal mass ratio.

[0015] Preferably, the first polyacid includes at least one of terephthalic acid, isophthalic acid, phthalic anhydride, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, stearic acid, and trimellitic anhydride.

[0016] Preferably, when the first polyacid comprises two or more components at the same time, the components are mixed in an equal mass ratio.

[0017] Preferably, the raw materials for preparing the high-toughness polyester resin further include at least one of a curing accelerator and an antioxidant.

[0018] Preferably, the polyamine includes at least one of benzyl diamine, 4,4-diaminodiphenylmethane, 1,6-hexanediamine and polyetheramine.

[0019] Preferably, the molecular weight of the polyetheramine is 230-5000 g / mol; further preferably, the molecular weight of the polyetheramine is 400-3000 g / mol; further preferably, the molecular weight of the polyetheramine is 400-2000 g / mol.

[0020] Preferably, when the polyamine comprises two or more components at the same time, the components are mixed in an equal mass ratio.

[0021] Preferably, the second polyol includes at least one of ethylene glycol, diethylene glycol, butanediol, hexanediol, neopentyl glycol, trimethylolpropane, 1,3-propylene glycol, 1,2-propylene glycol, ethylbutylpropylene glycol, polyethylene glycol and polypropylene glycol.

[0022] Preferably, the molecular weight of the polyethylene glycol and polypropylene glycol is 200-5000 g / mol; further preferably, the molecular weight of the polyethylene glycol and polypropylene glycol is 500-3500 g / mol; further preferably, the molecular weight of the polyethylene glycol and polypropylene glycol is 1000-2500 g / mol.

[0023] Preferably, when the second polyol comprises two or more components, the components are mixed in an equal mass ratio.

[0024] Preferably, the polyisocyanate includes at least one of isophorone diisocyanate, diphenylmethane diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, bis(4-isocyanatephenyl)methane, hexamethylene diisocyanate, naphthalene diisocyanate, 3,3'-dichlorobiphenyl-4,4'-diisocyanate, and 2,4-toluene diisocyanate.

[0025] Preferably, when the polyisocyanate comprises two or more components at the same time, the components are mixed in an equal mass ratio.

[0026] Preferably, the second polyacid includes at least one of nadic anhydride, methyl nadic anhydride, phthalic anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, trimellitic anhydride, pyromellitic anhydride and citric acid.

[0027] Preferably, when the second polyacid comprises two or more components at the same time, the components are mixed in an equal mass ratio.

[0028] Preferably, the raw materials for preparing the acidolysis agent also include a catalyst; the catalyst includes catalyst A and catalyst B; the catalyst A includes at least one of dibutyltin dilaurate, tin octoate, dibutyltin acetate, and dibutyltin oxide; the catalyst B includes at least one of lutidine, pyridine, and 4-dimethylaminopyridine.

[0029] Preferably, when catalyst A contains two or more components at the same time, the components are mixed in an equal mass ratio; when catalyst B contains two or more components at the same time, the components are mixed in an equal mass ratio.

[0030] Preferably, the mass ratio of the first polyol, the first polyacid and the acidolysis agent is (7.8-25.5):(15.8-45):1.

[0031] Further preferably, the mass ratio of the first polyol, the first polyacid, and the acidolysis agent is (9.8-23.5):(17.8-43):1.

[0032] Preferably, the molar ratio of the polyamine, the second polyol, the polyisocyanate, the second polyacid, the catalyst A and the catalyst B is (3.5-6500): (4.5-22000): (9-65000): (4.5-11000): (0.01-11): 1.

[0033] More preferably, the molar ratio of the polyamine, the second polyol, the polyisocyanate, the second polyacid, the catalyst A, and the catalyst B is (4-6000):(5-20000):(10-60000):(5-10000):(0.01-6):1.

[0034] The second aspect of the present invention provides a method for preparing the high-toughness polyester resin described in the first aspect of the present invention.

[0035] Specifically, the method for preparing the high-toughness polyester resin comprises the following steps:

[0036] (1) mixing the raw material components of the acidolysis agent, reacting them, and performing vacuum polycondensation to obtain the acidolysis agent;

[0037] (2) The first polyol and the first polyacid are mixed, subjected to a first reaction, and subjected to vacuum polycondensation. The mixture is then mixed with the acidolysis agent obtained in step (1) and subjected to a second reaction to obtain the high-toughness polyester resin.

[0038] Preferably, step (1) is specifically: mixing the polyamine, the second polyol, the polyisocyanate and the catalyst A, performing reaction 1 to obtain material A, performing reaction 2 on the material A and the second polyacid under the condition of catalyst B to obtain material B, and performing vacuum polycondensation on the material B to obtain the acidolysis agent;

[0039] Step (2) specifically comprises: mixing the first polyol and the first polyacid, carrying out reaction 3 to obtain material C, subjecting material C to vacuum polycondensation to obtain material D, and then mixing material D with the acidolysis agent obtained in step (1), carrying out reaction 4 to obtain the high-toughness polyester resin.

[0040] Preferably, in step (1), the reaction temperature of reaction 1 is 25-200°C, and the reaction time of reaction 1 is 0.5-5h; further preferably, in step (1), the reaction temperature of reaction 1 is 50-200°C, and the reaction time of reaction 1 is 0.5-3h; further preferably, in step (1), the reaction temperature of reaction 1 is 60-200°C, and the reaction time of reaction 1 is 0.5-2h.

[0041] Specifically, in step (1), both reaction 1 and reaction 2 are polymerization reactions, and the polymerization reactions are carried out under a nitrogen atmosphere.

[0042] Preferably, in step (1), the polymerization reaction includes any one of melt polymerization and solution polymerization. More preferably, in step (1), the polymerization reaction is melt polymerization.

[0043] Preferably, in step (1), the reaction temperature of reaction 2 is 150-250°C, and the reaction time of reaction 2 is 1-24h; preferably, in step (1), the reaction temperature of reaction 2 is 180-240°C, and the reaction time of reaction 2 is 8-18h.

[0044] Preferably, in step (1), the pressure of the vacuum polycondensation is 0.09-0.1 MPa, the temperature of the vacuum polycondensation is 150-220°C, and the time of the vacuum polycondensation is 0.5-2h; further preferably, in step (1), the pressure of the vacuum polycondensation is 0.094-0.0.96 MPa, the temperature of the vacuum polycondensation is 160-200°C, and the time of the vacuum polycondensation is 0.5-1h.

[0045] Preferably, in step (2), the reaction temperature of reaction 3 is 150-250°C; the reaction time of reaction 3 is 1-24h; further preferably, in step (2), the reaction temperature of reaction 3 is 180-240°C; the reaction time of reaction 3 is 8-12h.

[0046] Preferably, in step (2), the pressure of the vacuum polycondensation is 0.09-0.1 MPa, the temperature of the vacuum polycondensation is 220-240°C, and the time of the vacuum polycondensation is 0.5-3 h; further preferably, in step (2), the pressure of the vacuum polycondensation is 0.094-0.0.96 MPa, the temperature of the vacuum polycondensation is 225-235°C, and the time of the vacuum polycondensation is 0.5-2 h.

[0047] Preferably, in step (2), the reaction temperature of reaction 4 is 200-220°C; the reaction time of reaction 4 is 0.5-3h; further preferably, in step (2), the reaction temperature of reaction 4 is 205-215°C; the reaction time of reaction 4 is 1-2h.

[0048] Specifically, in step (2), the reaction 3 is an esterification polycondensation polymerization reaction, and the polymerization reaction is carried out under a nitrogen atmosphere.

[0049] Preferably, in step (2), the polymerization reaction includes any one of melt polymerization and solution polymerization. More preferably, in step (2), the polymerization reaction is melt polymerization.

[0050] Preferably, in step (2), a curing accelerator and an antioxidant are added after the reaction 4.

[0051] A third aspect of the present invention provides a coating.

[0052] Specifically, the coating comprises the high-toughness polyester resin described in the first aspect of the present invention, and epoxy resin.

[0053] Preferably, the paint is an indoor hybrid paint.

[0054] Preferably, the coating further comprises at least one of a filler, a matting agent, a leveling agent, and a degassing agent; further preferably, the coating further comprises a filler, a matting agent, a leveling agent, and a degassing agent.

[0055] Preferably, the mass ratio of the polyester resin, epoxy resin, filler, matting agent, leveling agent and deaerator is 360: (200-280): (300-440): (8-12): (8-12): (3-5); further preferably, the mass ratio of the polyester resin, epoxy resin, filler, matting agent, leveling agent and deaerator is 360: (220-260): (340-400): (9-11): (9-11): (3.5-4.5); further preferably, the mass ratio of the polyester resin, epoxy resin, filler, matting agent, leveling agent and deaerator is 360: 240: 376: 10: 10: 4.

[0056] Preferably, the epoxy resin comprises bisphenol A epoxy resin.

[0057] Preferably, the epoxy equivalent of the bisphenol A epoxy resin is 500-1000 g / mol; further preferably, the epoxy equivalent of the bisphenol A epoxy resin is 780-950 g / mol.

[0058] Preferably, the filler comprises barium sulfate.

[0059] Preferably, the matting agent includes at least one of a physical matting agent and a semi-physical and semi-chemical matting agent.

[0060] Preferably, the leveling agent comprises a siloxane-modified acrylic leveling agent.

[0061] Preferably, the degassing agent comprises benzoin.

[0062] Compared with the prior art, the technical solution provided by the present invention has the following beneficial effects:

[0063] (1) The acidolysis agent of the present invention is prepared by using polyamine, a second polyol, a polyisocyanate, a second polyacid, and a catalyst, and has a polyurea / polyurethane structure, increases intramolecular hydrogen bonds, and increases structural differences, so that the polyurea / polyurethane modified polyester resin has a suitable molecular weight, viscosity, glass transition temperature and reaction activity, and thus the polyester resin has excellent impact resistance, bending resistance, leveling, and easy matting performance after being cured into a film. The coating has a gloss of less than 10° and a smooth appearance, a delayed impact of more than 90 days, and a delayed bending performance of more than 30 days, which solves the problem that the matting, mechanical properties, and leveling properties of the hybrid powder coating cannot be taken into account at the same time.

[0064] (2) The preparation process of the present invention is simple and convenient for large-scale production and application. DETAILED DESCRIPTION

[0065] In order to make the technical scheme of the present invention more clearly understood by those skilled in the art, the following embodiments are listed for illustration. It should be pointed out that the following embodiments do not limit the protection scope of the present invention.

[0066] Unless otherwise specified, the raw materials, reagents or devices used in the following examples can be obtained from conventional commercial sources or by existing known methods.

[0067] Example 1

[0068] A method for preparing a high-toughness polyester resin comprises the following steps:

[0069] (1) 400 g of polyetheramine D400 (molecular weight 400 g / mol), 20 g of polyetheramine T403 (molecular weight 403 g / mol), 160 g of diethylene glycol, and 6 g of dibutyltin dilaurate were mixed, and the temperature was raised to 60° C. to obtain a molten mixture. 620 g of isophorone diisocyanate was slowly added to the molten mixture, and the mixture was reacted at 120° C. for 2 h. 1 g of 4-dimethylaminopyridine and 90 g of adipic anhydride were added, and the mixture was reacted at 160° C. for 1 h. Finally, the mixture was evacuated at a vacuum degree of -0.094 MPa for 1 h to obtain an acidolysis agent A.

[0070] (2) 2500 g of neopentyl glycol, 900 g of ethylene glycol, 1500 g of diethylene glycol, 9000 g of terephthalic acid, and 12 g of butyl stannoic acid are heated to 245° C. at a heating rate of 3° C. / 30 min under a nitrogen atmosphere, and kept warm for 4 h after reaching the set temperature; then the temperature is lowered to 230° C., and evacuated at a vacuum degree of -0.096 MPa for 1.5 h; the temperature is lowered to 210° C., 500 g of the acidolysis agent A obtained in step (1) is added, and the temperature is kept warm at 205° C. for 1 h; then 90 g of triphenylphosphine, 15 g of antioxidant 1010 and 15 g of antioxidant 264 are added, and the mixture is stirred for 1.0 h and then discharged to obtain a high-toughness polyester resin R1.

[0071] Example 2

[0072] A method for preparing a high-toughness polyester resin comprises the following steps:

[0073] (1) 900 g of polyetheramine ED900 (molecular weight 900 g / mol), 20 g of polyetheramine T403 (molecular weight 403 g / mol), 160 g of diethylene glycol, and 6 g of dibutyltin dilaurate were mixed, and the temperature was raised to 60° C. to obtain a molten mixture. 620 g of isophorone diisocyanate was slowly added to the molten mixture, and the mixture was reacted at 120° C. for 2 h. 1 g of 4-dimethylaminopyridine and 90 g of adipic anhydride were added, and the mixture was reacted at 160° C. for 1 h. Finally, the mixture was evacuated at a vacuum degree of -0.094 MPa for 1 h to obtain an acidolysis agent B.

[0074] (2) 2500 g of neopentyl glycol, 900 g of ethylene glycol, 1500 g of diethylene glycol, 9000 g of terephthalic acid, and 12 g of butyl stannoic acid were heated to 245°C at a heating rate of 3°C / 30 min under a nitrogen atmosphere, and kept at the set temperature for 4 h; then cooled to 230°C, and evacuated at a vacuum degree of -0.096 MPa for 1.5 h; cooled to 210°C, 500 g of acidolysis agent B was added, and kept at 205°C for 1 h; then 90 g of triphenylphosphine, 15 g of antioxidant 1010 and 15 g of antioxidant 264 were added, and the mixture was stirred for 1.0 h and then discharged to obtain a high-toughness polyester resin R2.

[0075] Example 3

[0076] A method for preparing a high-toughness polyester resin comprises the following steps:

[0077] (1) 500 g of polyethylene glycol 500 (molecular weight 500 g / mol), 20 g of polyetheramine T403 (molecular weight 403 g / mol), 345 g of polyetheramine D230 (molecular weight 230 g / mol), and 6 g of dibutyltin dilaurate were mixed, and the temperature was raised to 60° C. to obtain a molten mixture. 700 g of diphenylmethane diisocyanate was slowly added to the molten mixture, and the mixture was reacted at 120° C. for 2 h. 1 g of 4-dimethylaminopyridine and 105 g of phthalic anhydride were added, and the mixture was reacted at 200° C. for 1 h. Finally, the mixture was evacuated at a vacuum degree of -0.094 MPa for 1 h to obtain an acidolysis agent C.

[0078] (2) 2500 g of neopentyl glycol, 900 g of ethylene glycol, 1500 g of diethylene glycol, 9000 g of terephthalic acid, and 12 g of butyl stannoic acid were heated to 245°C at a heating rate of 3°C / 30 min under a nitrogen atmosphere, and kept at the set temperature for 4 h; then cooled to 230°C, and evacuated at a vacuum degree of -0.096 MPa for 1.5 h; cooled to 210°C, 500 g of acidolysis agent C was added, and kept at 205°C for 1 h; then 90 g of triphenylphosphine, 15 g of antioxidant 1010 and 15 g of antioxidant 264 were added, and the mixture was stirred for 1.0 h and then discharged to obtain a high-toughness polyester resin R3.

[0079] Example 4

[0080] A method for preparing a high-toughness polyester resin comprises the following steps:

[0081] (1) 1000 g of polyethylene glycol 1000 (molecular weight of 1000 g / mol), 20 g of polyetheramine T403 (molecular weight of 403 g / mol), 345 g of polyetheramine D230 (molecular weight of 230 g / mol), and 6 g of dibutyltin dilaurate were mixed, and the temperature was raised to 60° C. to obtain a molten mixture. 700 g of diphenylmethane diisocyanate was slowly added to the molten mixture, and the mixture was reacted at 120° C. for 2 h. 1 g of 4-dimethylaminopyridine and 105 g of phthalic anhydride were added, and the mixture was reacted at 200° C. for 1 h. Finally, the mixture was evacuated at a vacuum degree of -0.094 MPa for 1 h to obtain an acidolysis agent D.

[0082] (2) 2500 g of neopentyl glycol, 900 g of ethylene glycol, 1500 g of diethylene glycol, 9000 g of terephthalic acid, and 12 g of butyl stannoic acid were heated to 245°C at a heating rate of 3°C / 30 min under a nitrogen atmosphere, and kept at the set temperature for 4 h; then cooled to 230°C, and evacuated at a vacuum degree of -0.096 MPa for 1.5 h; cooled to 210°C, 500 g of acidolysis agent D was added, and kept at 205°C for 1 h; then 90 g of triphenylphosphine, 15 g of antioxidant 1010 and 15 g of antioxidant 264 were added, and the mixture was stirred for 1.0 h and then discharged to obtain a high-toughness polyester resin R4.

[0083] Comparative Example 1

[0084] Compared with Example 1, in Comparative Example 1, no diethylene glycol was added when preparing the acidolysis agent, that is, the prepared acidolysis agent did not contain a polyurethane structure but only a polyurea structure.

[0085] Comparative Example 1 A method for preparing a polyurea-modified polyester resin comprises the following steps:

[0086] 400 g of polyetheramine D400 (molecular weight 400 g / mol), 20 g of polyetheramine T403 (molecular weight 403 g / mol), and 6 g of dibutyltin dilaurate were mixed, and the temperature was raised to 60° C. to obtain a molten mixture. 620 g of isophorone diisocyanate was slowly added to the molten mixture, and reacted at 120° C. for 2 h; 1 g of 4-dimethylaminopyridine and 90 g of adipic anhydride were added, and reacted at 160° C. for 1 h; finally, vacuum was drawn at a vacuum degree of -0.094 MPa for 1 h to obtain an acidolysis agent E;

[0087] (2) 2500 g of neopentyl glycol, 900 g of ethylene glycol, 1500 g of diethylene glycol, 9000 g of terephthalic acid, and 12 g of butyl stannoic acid were heated to 245°C at a heating rate of 3°C / 30 min under a nitrogen atmosphere, and kept at the set temperature for 4 h; then the temperature was lowered to 230°C, and evacuated at a vacuum degree of -0.096 MPa for 1.5 h; the temperature was lowered to 210°C, 500 g of acidolysis agent E was added, and the mixture was kept at 205°C for 1 h; then 90 g of triphenylphosphine, 15 g of antioxidant 1010, and 15 g of antioxidant 264 were added, and the mixture was stirred for 1.0 h and then discharged to obtain polyester resin R5.

[0088] Comparative Example 2

[0089] Compared with Example 3, in Comparative Example 2, no polyamine was added when preparing the acidolysis agent, that is, the prepared acidolysis agent did not contain a polyurea structure but only a polyurethane structure.

[0090] Comparative Example 2 A method for preparing a polyurethane-modified polyester resin comprises the following steps:

[0091] (1) 1000 g of polyethylene glycol 1000 (molecular weight 1000 g / mol), 10 g of trimethylolpropane, and 6 g of dibutyltin dilaurate were mixed, and the temperature was raised to 60° C. to obtain a molten mixture. 700 g of diphenylmethane diisocyanate was slowly added to the molten mixture, and the mixture was reacted at 120° C. for 2 h. 1 g of 4-dimethylaminopyridine and 105 g of phthalic anhydride were added, and the mixture was reacted at 200° C. for 1 h. Finally, the mixture was evacuated at a vacuum degree of -0.094 MPa for 1 h to obtain an acidolysis agent F.

[0092] (2) 2500 g of neopentyl glycol, 900 g of ethylene glycol, 1500 g of diethylene glycol, 9000 g of terephthalic acid, and 12 g of butyl stannoic acid were heated to 245°C at a heating rate of 3°C / 30 min under a nitrogen atmosphere, and kept at the set temperature for 4 h; then cooled to 230°C, and evacuated at a vacuum degree of -0.096 MPa for 1.5 h; cooled to 210°C, 500 g of acidolysis agent F was added, and kept at 205°C for 1 h; then 90 g of triphenylphosphine, 15 g of antioxidant 1010 and 15 g of antioxidant 264 were added, and the mixture was stirred for 1.0 h and then discharged to obtain polyester resin R6.

[0093] Comparative Example 3

[0094] The difference between Comparative Example 3 and Example 1 is that the acidolysis agent in Comparative Example 3 is trimellitic anhydride.

[0095] Comparative Example 3 A method for preparing a polyester resin comprises the following steps:

[0096] 2500g of neopentyl glycol, 900g of ethylene glycol, 1500g of diethylene glycol, 9000g of terephthalic acid and 12g of butyl stannoic acid were heated to 245°C at a heating rate of 3°C / 30min under a nitrogen atmosphere, and kept warm for 4h after reaching the set temperature; then cooled to 230°C, and evacuated at a vacuum degree of -0.096MPa for 1.5h; cooled to 210°C, 200g of trimellitic anhydride was added and kept warm at 205°C for 1h; then 90g of triphenylphosphine, 15g of antioxidant 1010 and 15g of antioxidant 264 were added, and the mixture was stirred for 1.0h and then discharged to obtain polyester resin R7.

[0097] Comparative Example 4

[0098] The difference between Comparative Example 4 and Example 1 is that the acidolysis agent in Comparative Example 4 is isophthalic acid.

[0099] Comparative Example 4 A method for preparing a polyester resin comprises the following steps:

[0100] 2500g of neopentyl glycol, 900g of ethylene glycol, 1500g of diethylene glycol, 9000g of terephthalic acid and 12g of butyl stannoic acid were heated to 245°C at a heating rate of 3°C / 30min under a nitrogen atmosphere, and kept warm for 4h after reaching the set temperature; then the temperature was lowered to 230°C, and evacuated at a vacuum degree of -0.096MPa for 1.5h; the temperature was maintained at 230°C, 400g of isophthalic acid was added and kept warm at 205°C for 1h; then 90g of triphenylphosphine, 15g of antioxidant 1010 and 15g of antioxidant 264 were added, and the mixture was stirred for 1.0h and then discharged to obtain polyester resin R8.

[0101] Comparative Example 5

[0102] The only difference between Comparative Example 5 and Example 1 is that the acidolysis agent in Comparative Example 5 is adipic acid.

[0103] Comparative Example 5 A method for preparing a polyester resin comprises the following steps:

[0104] 2500g of neopentyl glycol, 900g of ethylene glycol, 1500g of diethylene glycol, 9000g of terephthalic acid and 12g of butyl stannoic acid were heated to 245°C at a heating rate of 3°C / 30min under a nitrogen atmosphere, and kept warm for 4h after reaching the set temperature; then cooled to 230°C, and evacuated at a vacuum degree of -0.096MPa for 1.5h; cooled to 190°C, 340g of adipic acid was added and kept warm at 180°C for 1h; then 90g of triphenylphosphine, 15g of antioxidant 1010 and 15g of antioxidant 264 were added, and the mixture was stirred for 1.0h and then discharged to obtain polyester resin R9.

[0105] Application Example 1

[0106] A coating, using the polyester resin prepared in Example 1, specifically, its composition and dosage are shown in Table 1.

[0107] A method for preparing a coating comprises the following steps:

[0108] The raw material components were uniformly mixed by a coffee grinder, and then melt-extruded, sheeted, and cooled by a twin-screw extruder at 100° C. The sheet material was crushed by a coffee grinder and sieved through a 180-mesh filter to obtain a coating.

[0109] Application Example 2-4

[0110] The difference between Application Examples 2-4 and Application Example 1 is that Application Examples 2-4 respectively use the polyester resins prepared in Example 2, Example 3, and Example 4, and the rest is the same as Application Example 1.

[0111] The compositions and dosages of Application Examples 2-4 are shown in Table 1, respectively.

[0112] Comparative Application Examples 1-5

[0113] The difference between comparative example application examples 1-5 and application example 1 is that comparative example application examples 1-5 respectively use the polyester resin prepared in comparative examples 1-5, and the rest is the same as application example 1.

[0114] The compositions and dosages of comparative application examples 1-5 are shown in Table 1, respectively.

[0115] Table 1: Composition and dosage of coatings of Application Examples 1-4 and Comparative Application Examples 1-5 (in g)

[0116]

[0117]

[0118] In Table 1, “-” means no addition.

[0119] Performance Testing

[0120] 1. Determination of polyester resin parameters

[0121] The acid value, viscosity, glass transition temperature and molecular weight of the polyester resins prepared in Examples 1-4 and Comparative Examples 1-5 were measured. The specific test results are shown in Table 2.

[0122] Table 2: Acid value, viscosity, glass transition temperature and molecular weight of polyester resins of Examples 1-4 and Comparative Examples 1-5

[0123] Group Polyester resin Acid value (mg KOH / g) Viscosity (mPa·s) Tg(℃) Molecular weight (g / mol) Example 1 R1 47.3 5300 55.6 14200 Example 2 R2 48.4 5500 54.3 13800 Example 3 R3 48.1 5450 54.7 13500 Example 4 R4 49.5 5340 56.1 14000 Comparative Example 1 R5 50.1 5350 54.6 11500 Comparative Example 2 R6 48.7 5430 55.3 11700 Comparative Example 3 R7 49.2 4540 55.2 9800 Comparative Example 4 R8 50.4 4780 54.8 10200 Comparative Example 5 R9 47.9 4600 52.4 10800

[0124] As can be seen from Table 2, the polyester resin prepared in the present invention has a higher molecular weight, which can make the prepared powder coating have better impact resistance and bending resistance. In addition, the polyurea / polyurethane modified polyester resin of the present invention has a more suitable viscosity, which is conducive to obtaining a smooth and smooth coating appearance.

[0125] 2. Coating performance test

[0126] The coatings prepared in Application Examples 1-4 and Comparative Application Examples 1-5 were sprayed on the surface treated carbon steel substrate using an electrostatic spray gun, and cured at 200°C / 10min to obtain a powder coating of 80-90μm, and then the performance test was carried out. The main test items and test methods are as follows:

[0127] 60° gloss test: refer to GB / T 9754-2007;

[0128] Tilt flow test: refer to GB / T 28861-2012;

[0129] Coating appearance test: visual observation;

[0130] Impact strength test: refer to GB / T 1732-1993;

[0131] Bending performance test: refer to GB / T 13448-2006.

[0132] The performance test results of the coatings of Application Examples 1-4 and Comparative Application Examples 1-5 are shown in Table 3.

[0133] Table 3: Performance test results of coatings in application examples 1-4 and comparative application examples 1-5

[0134]

[0135] It can be seen from Table 3 that the coating prepared by the polyester resin of the present invention has good impact resistance, bending resistance, 90-day delayed impact resistance and 30-day delayed bending resistance, and also has good gloss and coating film appearance, so that the hybrid powder coating also has good mechanical properties, leveling properties and easy matting properties.

[0136] In Comparative Example 1, no diethylene glycol was added when preparing the acidolysis agent, that is, the prepared acidolysis agent did not contain a polyurethane structure, so that the 90-day delayed impact strength, bending performance, 30-day delayed bending performance, and gloss of the coating of Comparative Application Example 1 were inferior to those of Example 1.

[0137] In Comparative Example 2, no polyamine was added when preparing the acidolysis agent, that is, the prepared acidolysis agent did not contain a polyurea structure, so that the 90-day delayed impact strength, bending performance, 30-day delayed bending performance, gloss and appearance of the coating of Comparative Application Example 2 were inferior to those of Example 1.

[0138] It can be seen from Comparative Examples 1 and 2 that, in the present invention, when preparing the acidolysis agent, polyamines and polyols play an important role. They work together with polyisocyanates to make the polyester resin have a polyurea / polyurethane structure, increase intramolecular hydrogen bonds, and increase structural differences. The obtained polyurea / polyurethane modified polyester resin has a suitable molecular weight, viscosity, glass transition temperature and reaction activity, so that the coating has excellent impact resistance, bending resistance, leveling and matting properties, which can solve the problem that the matting property, mechanical properties and leveling properties of the hybrid powder coating cannot be taken into account at the same time.

[0139] Comparative Examples 3, 4 and 5 respectively use trimellitic anhydride, isophthalic acid and adipic acid as acidolysis agents to prepare polyester resins. After the prepared polyester resins are applied to the coating, the gloss, 90-day delayed impact performance, bending performance and 30-day delayed bending performance of the coating are all worse than those of Example 1. This shows that the polyurea / polyurethane modified polyester resin prepared by the specific acidolysis agent of the present invention can make the coating have good impact resistance, bending resistance, leveling and matting performance, and can solve the problem that the matting property, mechanical properties and leveling property of the hybrid powder coating cannot be taken into account at the same time.

[0140] In summary, the present invention adopts polyamine, second polyol, polyisocyanate, second polyacid and catalyst to prepare acidolysis agent, which has polyurea / polyurethane structure, so that the polyester resin modified by polyurea / polyurethane has polyurea / polyurethane structure, increases intramolecular hydrogen bonds, increases structural differences, and the obtained polyester resin has suitable molecular weight, viscosity, glass transition temperature and reaction activity, so that the polyester resin has excellent impact resistance, bending resistance, leveling and easy matting performance after curing into film, the coating gloss is below 10° and the appearance is flat and smooth, the delayed impact is greater than 90 days, and the delayed bending performance is greater than 30 days, which solves the problem that the matting property, mechanical properties and leveling property of hybrid powder coating cannot be taken into account at the same time.

[0141] The above embodiments are only used to illustrate the technical solution of the present invention rather than to limit the protection scope of the present invention. Although the present invention has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that the technical solution of the present invention can be modified or replaced by equivalents without departing from the essence and scope of the technical solution of the present invention.

Claims

1. A polyester resin, It is characterized in that The raw materials for its preparation include a first polyol, a first polyacid, and an acidolysis agent; The raw materials for preparing the acidolysis agent include polyamine, a second polyol, polyisocyanate, and a second polyacid; The first polyol is the same as or different from the second polyol; the first polyacid is the same as or different from the second polyacid.

2. The polyester resin according to claim 1, It is characterized in that The first polyol includes at least one of ethylene glycol, 1.3-propylene glycol, 1.2-propylene glycol, 1.4-butylene glycol, neopentyl glycol, diethylene glycol, hexylene glycol, trimethylolpropane, ethyl butyl propane glycol, 1.4-cyclohexanediol, and pentaerythritol; And / or, the first polyacid includes at least one of terephthalic acid, isophthalic acid, phthalic anhydride, adipic acid, azelaic acid, sebacic acid, dodecanedioic acid, stearic acid, and trimellitic anhydride.

3. The polyester resin according to claim 1, It is characterized in that The polyamine includes at least one of benzyl diamine, 4,4-diaminodiphenylmethane, 1,6-hexanediamine, and polyetheramine; and / or, the second polyol comprises at least one of ethylene glycol, diethylene glycol, butanediol, hexanediol, neopentyl glycol, trimethylolpropane, 1,3-propylene glycol, 1,2-propylene glycol, ethylbutylpropylene glycol, polyethylene glycol and polypropylene glycol; And / or, the polyisocyanate includes at least one of isophorone diisocyanate, diphenylmethane diisocyanate, p-phenylene diisocyanate, m-phenylene diisocyanate, bis(4-isocyanatephenyl)methane, hexamethylene diisocyanate, naphthalene diisocyanate, 3,3'-dichlorobiphenyl-4,4'-diisocyanate, and 2,4-toluene diisocyanate; And / or, the second polyacid includes at least one of nadic anhydride, methyl nadic anhydride, phthalic anhydride, succinic anhydride, glutaric anhydride, adipic anhydride, trimellitic anhydride, pyromellitic anhydride and citric acid.

4. The polyester resin according to claim 1, It is characterized in that The raw materials for preparing the acidolysis agent also include a catalyst; the catalyst includes catalyst A and catalyst B; the catalyst A includes at least one of dibutyltin dilaurate, tin octoate, dibutyltin acetate, and dibutyltin oxide; the catalyst B includes at least one of lutidine, pyridine, and 4-dimethylaminopyridine.

5. The polyester resin according to claim 1, It is characterized in that The mass ratio of the first polyol, the first polyacid and the acidolysis agent is (7.8-25.5):(15.8-45):

1.

6. The polyester resin according to claim 4, It is characterized in that The molar ratio of the polyamine, the second polyol, the polyisocyanate, the second polyacid, the catalyst A and the catalyst B is (3.5-6500): (4.5-22000): (9-65000): (4.5-11000): (0.01-11):

1.

7. A method for preparing a polyester resin according to any one of claims 1 to 6, It is characterized in that The following steps are involved: (1) mixing and reacting the raw material components of the acidolysis agent to obtain the acidolysis agent; (2) The first polyol and the first polyacid are mixed to carry out a first reaction, and then mixed with the acidolysis agent obtained in step (1) to carry out a second reaction to obtain the polyester resin.

8. The preparation method according to claim 7, It is characterized in that Step (1) specifically comprises: mixing the polyamine, the second polyol, the polyisocyanate and the catalyst A, performing reaction 1 to obtain material A, performing reaction 2 on the material A and the second polyacid under the condition of catalyst B to obtain material B, and performing vacuum polycondensation on the material B to obtain the acidolysis agent; Step (2) specifically comprises: mixing the first polyol and the first polyacid, carrying out reaction 3 to obtain material C, subjecting material C to vacuum polycondensation to obtain material D, and then mixing material D with the acidolysis agent obtained in step (1), carrying out reaction 4 to obtain the polyester resin.

9. The preparation method according to claim 8, It is characterized in that In step (1), the reaction temperature of reaction 1 is 25-200° C., and the reaction time of reaction 1 is 0.5-5 h; the reaction temperature of reaction 2 is 150-250° C., and the reaction time of reaction 2 is 1-24 h; And / or, in step (1), the pressure of the vacuum polycondensation is 0.09-0.1 MPa, the temperature of the vacuum polycondensation is 150-220° C., and the time of the vacuum polycondensation is 0.5-2 h; And / or, in step (2), the reaction temperature of reaction 3 is 150-250° C.; the reaction time of reaction 3 is 1-24 h; And / or, in step (2), the pressure of the vacuum polycondensation is 0.09-0.1 MPa, the temperature of the vacuum polycondensation is 220-240° C., and the time of the vacuum polycondensation is 0.5-3 h; And / or, in step (2), the reaction temperature of reaction 4 is 200-220° C.; the reaction time of reaction 4 is 0.5-3 h.

10. A coating, It is characterized in that The invention comprises the polyester resin according to any one of claims 1 to 6, and an epoxy resin.

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