A method for preparing impact-resistant and heat-resistant polyester resin

Abstract

The invention relates to the technical field of polyester resins, and discloses a method for preparing an impact-resistant and heat-resistant polyester resin. The invention uses neopentyl glycol and triethylsilanediol monomers as polyols, and carries out esterification polycondensation reaction with terephthalic acid, etc., and the obtained polyester resins have moderate acid value and viscosity value, and high glass transition temperature. A heat-resistant silicone structure is introduced into the side chain of the polyester resin. At the same time, the silicone structure has strong hydrophobicity, and produces steric hindrance and shielding effects on the side chain, making it difficult for water molecules to attack the ester bonds in the polyester main chain, thereby improving the boiling and hydrolysis resistance of the polyester resin, and improving the flexibility and impact strength of the polyester resin cured product, and having better impact resistance.

Description

Technical Field

[0001] The invention relates to the technical field of polyester resins, in particular to a method for preparing an impact-resistant and heat-resistant polyester resin. Background Art

[0002] Polyester resin is a polymer compound formed by polycondensation of polyols and polyacids. It has the advantages of excellent mechanical properties, high hardness, high transparency, good gloss, etc. It is widely used in powder coatings, hard plastics, adhesives, etc. Traditional polyester resins have low impact resistance, are easily hydrolyzed, and have poor water resistance, which limits the practical application of polyester resins in outdoor coatings, high-performance plastics, etc.

[0003] Patent CN102977351B discloses a method for preparing a modified polyester resin and a coating containing the polyester resin. The modified polyester resin and its coating are prepared using diols such as neopentyl glycol, triols such as trimethylolpropane, silanols such as heptaphenylsilsesquioxane trisilanol, silicone oligomers, isophthalic acid, etc. as raw materials. The modified polyester resin and its coating have good high temperature resistance and flexibility. However, this patent improves the problem of poor impact resistance and other properties of the polyester resin. Summary of the invention

[0004] The invention solves the problem that the polyester resin has poor performances such as impact resistance, water resistance and heat resistance.

[0005] The technical scheme of the present invention is as follows: a method for preparing an impact-resistant and heat-resistant polyester resin: adding polyol, dibasic acid and esterification catalyst into a reaction kettle, introducing nitrogen, heating while stirring, firstly keeping the temperature at 170-185°C for 1-2h, then heating to 240-255°C, keeping the temperature for 12-18h, discharging water generated by the esterification reaction, adding an acidolysis agent when the acid value reaches 5-20 mg KOH / g, and reacting for 3-4h; when the acid value reaches 50-80 mg KOH / g, evacuating to a vacuum degree of 10-20Pa, and carrying out a polycondensation reaction for 2-3h; when the acid value reaches 40-50 mg KOH / g, adding an onium salt curing accelerator and an antioxidant, stirring for 30-40 min, discharging, cooling and crushing to obtain an impact-resistant and heat-resistant polyester resin.

[0006] Preferably, the amount of polyol is 34-44 parts by weight, the dibasic acid is 48-52 parts by weight, the esterification catalyst is 0.32-0.48 parts by weight, the acidolysis agent is 18-21 parts by weight, the onium salt curing accelerator is 0.1-0.13 parts by weight, and the antioxidant is 0.45-0.52 parts by weight.

[0007] Preferably, the antioxidant is any one or a combination of hindered phenol antioxidants and phosphite antioxidants.

[0008] Preferably, the esterification catalyst is monobutyltin oxide. The onium salt curing accelerator is triphenylethylphosphonium bromide.

[0009] Preferably, the dibasic acid is terephthalic acid. The acidolysis agent includes any one or a combination of isophthalic acid, 1,4-cyclohexanedicarboxylic acid, and trimethylolpropane.

[0010] Preferably, the polyol is a combination of neopentyl glycol and triethylsilanediol monomers. The preparation method of triethylsilanediol monomers comprises:

[0011] (1) Add acetonitrile, 100 parts by weight of amino-bis(monopolyethylene glycol-hydroxy) (CAS No. 54384-47-3), 63-69 parts by weight of 3-bromopropylene, and 78-92 parts by weight of potassium carbonate to a reaction vessel, heat to 80-85°C, condense and reflux for 18-24 hours, remove acetonitrile by vacuum distillation, add water, extract with ethyl acetate, remove water from the organic phase with anhydrous sodium sulfate, filter, vacuum distill the filtrate, and dry to obtain an intermediate. The reaction formula is:

[0012] .

[0013] (2) Add tetrahydrofuran, 100 parts by weight of the intermediate, 50-55 parts by weight of triethylsilane, and a tetrahydrofuran solution containing 0.009-0.012 parts by weight of chloroplatinic acid into a reaction vessel, heat to 60-70°C in a nitrogen atmosphere, condense and reflux for 12-18 hours, remove tetrahydrofuran by vacuum distillation, add water, extract with ethyl acetate, remove water from the organic phase with anhydrous sodium sulfate, filter, vacuum distill the filtrate, and dry to obtain triethylsilanediol monomer. The reaction formula is:

[0014] .

[0015] Technical effect of the present invention: The present invention uses neopentyl glycol and triethylsilanediol monomers as polyols to carry out esterification polycondensation reaction with terephthalic acid, etc., and the obtained polyester resin has a moderate acid value and viscosity value. In addition, a high-temperature resistant organic silicon structure is introduced into the polyester molecular chain, which is beneficial to improving the heat resistance of the polyester resin and having a higher glass transition temperature.

[0016] The present invention introduces a heat-resistant silicone structure into the side chain of the polyester resin, and the silicone structure has strong hydrophobicity, which produces steric hindrance and shielding effects on the side chain, making it difficult for water molecules to attack the ester bonds in the polyester main chain, thereby improving the boiling and hydrolysis resistance of the polyester resin. In addition, the triethylsilanediol monomer contains a flexible ether bond, which is introduced into the main chain of the polyester resin to improve the flexibility and impact strength of the polyester resin cured product, and the impact resistance is better. DETAILED DESCRIPTION

[0017] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0018] Embodiment 1:

[0019] (1) Add 25 mL of acetonitrile, 2 g of amino-bis(monopolyethylene glycol-hydroxy), 1.26 g of 3-bromopropylene, and 1.84 g of potassium carbonate to a reaction vessel, heat to 80°C, condense and reflux for 24 h, remove the acetonitrile by vacuum distillation, add water, extract with ethyl acetate, remove water from the organic phase with anhydrous sodium sulfate, filter, and vacuum distill the filtrate and dry to obtain an intermediate.

[0020] (2) Add 30 mL of tetrahydrofuran, 3 g of the intermediate, 1.5 g of triethylsilane, and 2 mL of a tetrahydrofuran solution containing 0.27 mg of chloroplatinic acid into a reaction vessel, heat to 65°C in a nitrogen atmosphere, condense and reflux for 18 h, remove the tetrahydrofuran by vacuum distillation, add water, extract with ethyl acetate, remove water from the organic phase with anhydrous sodium sulfate, filter, and vacuum distill the filtrate and dry to obtain triethylsilanediol monomer.

[0021] (3) Add 30g of neopentyl glycol, 4g of triethylsilanediol monomer, 48g of terephthalic acid, and 0.32g of esterification catalyst monobutyltin oxide to the reactor, introduce nitrogen, and heat while stirring. First, keep the temperature at 175°C for 2h, then raise the temperature to 255°C and keep the temperature for 12h. Discharge the water generated by the esterification reaction. When the acid value reaches 20 mg KOH / g, add 15.2g of isophthalic acid, 3g of 1,4-cyclohexanedicarboxylic acid, and 1.7g of trimethylolpropane. React for 3h. When the acid value reaches 50 mg KOH / g, evacuate to a vacuum degree of 10Pa and carry out polycondensation reaction for 2h. When the acid value reaches 40 mg KOH / g, add 0.1g of onium salt curing accelerator triphenylethyl phosphonium bromide and 0.32g of hindered phenol antioxidant 1076 and 0.17g of phosphite antioxidant 168. Stir for 30min. min, discharging, cooling and crushing to obtain impact-resistant and heat-resistant polyester resin.

[0022] Embodiment 2:

[0023] (1) Add 30 mL of acetonitrile, 2 g of amino-bis(monopolyethylene glycol-hydroxy), 1.38 g of 3-bromopropylene, and 1.72 g of potassium carbonate to a reaction vessel, heat to 80°C, condense and reflux for 24 h, remove acetonitrile by vacuum distillation, add water, extract with ethyl acetate, remove water from the organic phase with anhydrous sodium sulfate, filter, and vacuum distill the filtrate and dry to obtain an intermediate.

[0024] (2) Add 40 mL of tetrahydrofuran, 3 g of the intermediate, 1.65 g of triethylsilane, and 2 mL of a tetrahydrofuran solution containing 0.36 mg of chloroplatinic acid into a reaction vessel, heat to 60°C in a nitrogen atmosphere, condense and reflux for 18 h, remove the tetrahydrofuran by vacuum distillation, add water, extract with ethyl acetate, remove water from the organic phase with anhydrous sodium sulfate, filter, and vacuum distill the filtrate and dry to obtain triethylsilanediol monomer.

[0025] (3) Add 30 g of neopentyl glycol, 9 g of triethylsilanediol monomer, 50.3 g of terephthalic acid, and 0.48 g of esterification catalyst monobutyltin oxide to the reactor, introduce nitrogen, and heat while stirring. First, keep the temperature at 170°C for 2 h, then raise the temperature to 250°C and keep the temperature for 12 h. Discharge the water generated by the esterification reaction. When the acid value reaches 20 mg KOH / g, add 13.3 g of isophthalic acid, 3 g of 1,4-cyclohexanedicarboxylic acid, and 1.7 g of trimethylolpropane. React for 4 h. When the acid value reaches 80 mg KOH / g, evacuate to a vacuum degree of 20 Pa and carry out polycondensation for 3 h. When the acid value reaches 50 mg KOH / g, add 0.12g onium salt curing accelerator triphenylethyl phosphonium bromide and 0.31g hindered phenol antioxidant 1076, 0.14g phosphite antioxidant 168, stir for 300min, discharge, cool and crush to obtain impact-resistant and heat-resistant polyester resin.

[0026] Embodiment 3:

[0027] (1) Add 25 mL of acetonitrile, 2 g of amino-bis(monopolyethylene glycol-hydroxy), 1.26 g of 3-bromopropylene, and 1.56 g of potassium carbonate to a reaction vessel, heat to 85°C, condense and reflux for 18 h, remove acetonitrile by vacuum distillation, add water, extract with ethyl acetate, remove water from the organic phase with anhydrous sodium sulfate, filter, and vacuum distill the filtrate and dry to obtain an intermediate.

[0028] (2) Add 30 mL of tetrahydrofuran, 3 g of the intermediate, 1.57 g of triethylsilane, and 2 mL of a tetrahydrofuran solution containing 0.3 mg of chloroplatinic acid into a reaction vessel, heat to 70°C in a nitrogen atmosphere, condense and reflux for 12 h, remove the tetrahydrofuran by vacuum distillation, add water, extract with ethyl acetate, remove water from the organic phase with anhydrous sodium sulfate, filter, and vacuum distill the filtrate and dry to obtain triethylsilanediol monomer.

[0029] (3) Add 30 g of neopentyl glycol, 14 g of triethylsilanediol monomer, 52 g of terephthalic acid, and 0.48 g of esterification catalyst monobutyl tin oxide to the reactor, introduce nitrogen, and heat while stirring. First, keep the temperature at 185°C for 1 hour, then heat to 240°C and keep the temperature for 18 hours. Discharge the water generated by the esterification reaction. When the acid value reaches 5 mg KOH / g, add 15.2 g of isophthalic acid, 3.8 g of 1,4-cyclohexanedicarboxylic acid, and 2 g of trimethylolpropane. React for 4 hours. When the acid value reaches 80 mg KOH / g, evacuate to a vacuum degree of 10 Pa and carry out polycondensation reaction for 2 hours. When the acid value reaches 50 mg KOH / g, add 0.13 g of onium salt curing accelerator triphenylethyl phosphonium bromide and 0.37 g of hindered phenol antioxidant 1076 and 0.16 g of phosphite antioxidant 168. Stir for 40 minutes. min, discharging, cooling and crushing to obtain impact-resistant and heat-resistant polyester resin.

[0030] Comparative Example 1: The main difference between this comparative example and Example 1 is that neopentyl glycol is used instead of triethylsilanediol monomer.

[0031] (1) Add 38 g of neopentyl glycol, 48 g of terephthalic acid, and 0.32 g of esterification catalyst monobutyl tin oxide to a reactor, introduce nitrogen, and heat while stirring. First, keep the temperature at 175°C for 2 h, then heat to 255°C and keep the temperature for 12 h. Discharge the water generated by the esterification reaction. When the acid value reaches 20 mg KOH / g, add 15.2 g of isophthalic acid, 3 g of 1,4-cyclohexanedicarboxylic acid, and 1.7 g of trimethylolpropane. React for 3 h. When the acid value reaches 50 mg KOH / g, evacuate to a vacuum degree of 10 Pa and carry out polycondensation for 2 h. When the acid value reaches 40 mg KOH / g, add 0.1 g of onium salt curing accelerator triphenylethyl phosphonium bromide and 0.32 g of hindered phenol antioxidant 1076 and 0.17 g of phosphite antioxidant 168. Stir for 30 min. min, discharging, cooling and crushing to obtain polyester resin.

[0032] Comparative Example 2: The main difference between this comparative example and Example 1 is that the intermediate is used instead of the triethylsilanediol monomer.

[0033] (1) Add 30g neopentyl glycol and 4g intermediate ( ), 48g terephthalic acid, 0.32g esterification catalyst monobutyl tin oxide, nitrogen was introduced, the temperature was raised while stirring, first at 175°C for 2h, then the temperature was raised to 255°C, the temperature was raised for 12h, the water generated by the esterification reaction was discharged, and when the acid value reached 20 mg KOH / g, 15.2g isophthalic acid, 3g 1,4-cyclohexanedicarboxylic acid, and 1.7g trimethylolpropane were added, and the reaction was carried out for 3h; when the acid value reached 50 mg KOH / g, the vacuum was evacuated to a vacuum degree of 10Pa, and the condensation reaction was carried out for 2h; when the acid value reached 40 mg KOH / g, 0.1g onium salt curing accelerator triphenylethyl phosphonium bromide and 0.32g hindered phenol antioxidant 1076 and 0.17g phosphite antioxidant 168 were added, stirred for 30 min, discharged, cooled, and crushed to obtain a polyester resin.

[0034] Comparative Example 3: The main difference between this comparative example and Example 1 is that N-allyldiethanolamine is used instead of the intermediate to prepare triethylsilanediol monomer.

[0035] (1) Add 30 mL of tetrahydrofuran and 1.87 g of N-allyldiethanolamine (CAS No. 2424-05-7, structural formula: ), 1.5g triethylsilane, 2mL tetrahydrofuran solution containing 0.27mg chloroplatinic acid, heated to 65°C in a nitrogen atmosphere, condensed and refluxed for 18h, tetrahydrofuran was removed by vacuum distillation, water was added, extracted with ethyl acetate, the organic phase was dehydrated with anhydrous sodium sulfate, filtered, the filtrate was vacuum distilled, and dried to obtain triethylsilanediol monomer. The structural formula is .

[0036] (2) Add 30 g of neopentyl glycol, 4 g of triethylsilanediol monomer, 48 g of terephthalic acid, and 0.32 g of esterification catalyst monobutyltin oxide to the reactor, introduce nitrogen, and heat while stirring. First, keep the temperature at 175°C for 2 h, then heat to 255°C and keep the temperature for 12 h. Discharge the water generated by the esterification reaction. When the acid value reaches 20 mg KOH / g, add 15.2 g of isophthalic acid, 3 g of 1,4-cyclohexanedicarboxylic acid, and 1.7 g of trimethylolpropane. React for 3 h. When the acid value reaches 50 mg KOH / g, evacuate to a vacuum degree of 10 Pa and carry out polycondensation for 2 h. When the acid value reaches 40 mg KOH / g, add 0.1 g of onium salt curing accelerator triphenylethyl phosphonium bromide and 0.32 g of hindered phenol antioxidant 1076 and 0.17 g of phosphite antioxidant 168. Stir for 30 min. min, discharging, cooling and crushing to obtain polyester resin.

[0037] Refer to GB / T 6743-2008 standard to test the acid value of polyester resin.

[0038] The viscosity of the polyester resin was tested using a viscometer with the temperature set at 200°C. After the temperature stabilized, a polyester resin sample was taken and placed in the center of the test table of the viscometer for viscosity measurement.

[0039] The polyester sample was tested by differential scanning calorimetry. 10 mg of polyester resin sample was weighed and placed on the stage. After setting the parameters in the program, DSC measurement was performed. The measurement temperature range was 25-100°C and the heating rate was 10°C / min. The test results are shown in Table 1.

[0040] Table 1 Polyester resin performance test

[0041]

[0042] After testing, the polyester resins prepared in each embodiment have moderate acid value and viscosity value. In addition, each embodiment has high glass transition temperature and better heat resistance, mainly because the triethylsilanediol monomer is added, and a high temperature resistant organic silicon structure is introduced into the polyester molecular chain, which is beneficial to improve the heat resistance of the polyester resin.

[0043] 100g of polyester resin and 9.6g of HAA hydroxyalkylamide curing agent were stirred and mixed, extruded by a twin-screw extruder, tableted, crushed, sieved, and then sprayed on the substrate by electrostatic spraying, and cured at 180°C for 20 minutes. The boiling water immersion test was tested according to GB / T1733-1993 standard.

[0044] The impact strength of polyester resin cured product was tested according to GB / T 1043.1-2008 standard.

[0045] Table 2 Performance test of polyester resin cured product

[0046]

[0047] After testing, compared with Comparative Example 1, triethylsilanediol monomer was added to the polyester resin of Examples 1-3, and a heat-resistant silicone structure was introduced into the side chain of the polyester resin. The silicone structure has strong hydrophobicity, which produces steric hindrance and shielding effects on the side chain, making it difficult for water molecules to attack the ester bonds in the polyester main chain, thereby improving the boiling and hydrolysis resistance of the polyester resin. In addition, triethylsilanediol monomer contains a flexible ether bond, which is introduced into the main chain of the polyester resin to improve the flexibility and impact strength of the cured product, and the impact resistance is very good.

[0048] The intermediate of Comparative Example 2 does not contain an organosilicon structure, resulting in poor heat resistance, boiling resistance and hydrolysis resistance of the polyester resin.

[0049] The triethylsilanediol monomer of Comparative Example 3 does not contain a flexible ether bond, resulting in poor flexibility and impact resistance of the polyester resin curing agent and low impact strength.

[0050] This specific embodiment is merely an explanation of the present application and is not a limitation of the present application. After reading this specification, those skilled in the art may make modifications to the present embodiment without any creative contribution as needed, but such modifications are protected by the patent law as long as they are within the scope of the claims of the present application.

Claims

1. A method for preparing an impact-resistant and heat-resistant polyester resin, characterized in that: The preparation method comprises: adding polyol, dibasic acid and esterification catalyst into a reaction kettle, introducing nitrogen, raising the temperature while stirring, first keeping the temperature at 170-185°C for 1-2h, then raising the temperature to 240-255°C, keeping the temperature for 12-18h, discharging water generated by the esterification reaction, adding an acidolysis agent when the acid value reaches 5-20 mgKOH / g, and reacting for 3-4h; when the acid value reaches 50-80 mg KOH / g, evacuating to a vacuum degree of 10-20Pa, and carrying out polycondensation reaction for 2-3h; when the acid value reaches 40-50 mg KOH / g, adding an onium salt curing accelerator and an antioxidant, stirring for 30-40 min, discharging, cooling and crushing to obtain an impact-resistant and heat-resistant polyester resin; The polyol is a combination of neopentyl glycol and triethylsilanediol monomers; The structural formula of the triethylsilanediol monomer is: .

2. The method for preparing the impact-resistant and heat-resistant polyester resin according to claim 1, characterized in that: The dosage of the polyol is 34-44 parts by weight, the dibasic acid is 48-52 parts by weight, the esterification catalyst is 0.32-0.48 parts by weight, the acidolysis agent is 18-21 parts by weight, the onium salt curing accelerator is 0.1-0.13 parts by weight, and the antioxidant is 0.45-0.52 parts by weight.

3. The method for preparing the impact-resistant and heat-resistant polyester resin according to claim 2, characterized in that: The antioxidant is any one or a combination of hindered phenol antioxidants and phosphite antioxidants.

4. The method for preparing the impact-resistant and heat-resistant polyester resin according to claim 2, characterized in that: The esterification catalyst is monobutyltin oxide.

5. The method for preparing the impact-resistant and heat-resistant polyester resin according to claim 2, characterized in that: The onium salt curing accelerator is triphenylethylphosphonium bromide.

6. The method for preparing the impact-resistant and heat-resistant polyester resin according to claim 2, characterized in that: The dibasic acid is terephthalic acid.

7. The method for preparing the impact-resistant and heat-resistant polyester resin according to claim 2, characterized in that: The acidolysis agent includes any one or a combination of isophthalic acid, 1,4-cyclohexanedicarboxylic acid, and trimethylolpropane.

8. The method for preparing the impact-resistant and heat-resistant polyester resin according to claim 1, characterized in that: The preparation method of the triethylsilanediol monomer comprises: (1) Add acetonitrile, amino-bis(monopolyethylene glycol-hydroxy), 3-bromopropylene and potassium carbonate to a reaction vessel, heat to 80-85°C, condense and reflux for 18-24 hours, distill under reduced pressure, extract and dry to obtain an intermediate; (2) Add tetrahydrofuran, the intermediate, triethylsilane, and a tetrahydrofuran solution of chloroplatinic acid into a reaction vessel, heat to 60-70° C. in a nitrogen atmosphere, condense and reflux for 12-18 hours, extract by distillation under reduced pressure, and dry to obtain triethylsilanediol monomer.

9. The method for preparing the impact-resistant and heat-resistant polyester resin according to claim 8, characterized in that: In the above (1), the amount of amino-bis(monopolyethylene glycol-hydroxy) used is 100 parts by weight, the amount of 3-bromopropylene is 63-69 parts by weight, and the amount of potassium carbonate is 78-92 parts by weight.

10. The method for preparing the impact-resistant and heat-resistant polyester resin according to claim 8, characterized in that: In the above (2), the amount of the intermediate used is 100 parts by weight, the amount of triethylsilane is 50-55 parts by weight, and the amount of chloroplatinic acid is 0.009-0.012 parts by weight.

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