CN116693830A - Method for preparing modified PETG copolyester by adopting quaternary ammonium titanium/zirconium chelate catalyst - Google Patents

Method for preparing modified PETG copolyester by adopting quaternary ammonium titanium/zirconium chelate catalyst Download PDF

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CN116693830A
CN116693830A CN202310988244.4A CN202310988244A CN116693830A CN 116693830 A CN116693830 A CN 116693830A CN 202310988244 A CN202310988244 A CN 202310988244A CN 116693830 A CN116693830 A CN 116693830A
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catalyst
quaternary ammonium
preparing
zirconium chelate
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CN116693830B (en
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张迅
王敏
岳林
李西春
廖广明
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Fuhai Dongying New Material Technology Co ltd
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    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
    • C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
    • C08G63/16—Dicarboxylic acids and dihydroxy compounds
    • C08G63/18—Dicarboxylic acids and dihydroxy compounds the acids or hydroxy compounds containing carbocyclic rings
    • C08G63/199—Acids or hydroxy compounds containing cycloaliphatic rings
    • C—CHEMISTRY; METALLURGY
    • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
    • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
    • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
    • C08G63/78—Preparation processes
    • C08G63/82—Preparation processes characterised by the catalyst used
    • C08G63/85—Germanium, tin, lead, arsenic, antimony, bismuth, titanium, zirconium, hafnium, vanadium, niobium, tantalum, or compounds thereof
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    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/52—Improvements relating to the production of bulk chemicals using catalysts, e.g. selective catalysts

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Abstract

The invention belongs to the technical field of preparation of high polymer materials, and particularly relates to a method for preparing modified PETG copolyester by using a quaternary ammonium titanium/zirconium chelate catalyst. The method for preparing the modified PETG copolyester by adopting the quaternary ammonium titanium/zirconium chelate catalyst comprises the following steps: mixing terephthalic acid, 1, 4-cyclohexanedimethanol and ethylene glycol, and carrying out esterification reaction to obtain an oligomer a; mixing hydrogenated bisphenol A with ethylene glycol for dissolution, adding terephthalic acid and a catalyst for pulping, and carrying out esterification reaction to obtain an oligomer b; polycondensation reaction: mixing the oligomer a with the oligomer b, an antioxidant and a catalyst, carrying out a step-type vacuum pre-polycondensation reaction, and then carrying out a final polycondensation reaction to obtain a modified PETG product; according to the method for preparing the modified PETG copolyester by using the quaternary ammonium titanium/zirconium chelate catalyst, the prepared PETG copolyester has the advantages of bright color, good yellowing resistance, good heat resistance and good mechanical property.

Description

Method for preparing modified PETG copolyester by adopting quaternary ammonium titanium/zirconium chelate catalyst
Technical Field
The invention belongs to the technical field of preparation of high polymer materials, and particularly relates to a method for preparing modified PETG copolyester by using a quaternary ammonium titanium/zirconium chelate catalyst.
Background
Polyethylene terephthalate-1, 4-cyclohexanedimethanol ester (PETG) is a copolyester prepared from terephthalic acid (PTA), ethylene Glycol (EG) and 1, 4-Cyclohexanedimethanol (CHDM) through esterification and polycondensation. PETG has good toughness, transparency, workability, chemical resistance, and low hygroscopicity, and is easy to process, thus being widely used.
But PETG itself is poor in heat resistance, limiting its application in heat resistant containers, medical devices, and the like. The traditional PETG contains a small amount of 1, 4-cyclohexanedimethanol, is primary alcohol, has a monocyclohexane structure, has poor rigidity and has small influence on the glass transition temperature. The hydrogenated bisphenol A is secondary alcohol, has a dicyclohexyl structure, has high rigidity, and has small flexibility, and the formed ester group is directly connected with cyclohexane and benzene ring if the hydrogenated bisphenol A is applied to PETG, so that the glass transition temperature of the PETG can be effectively improved, and the heat resistance and the mechanical property of the PETG are improved. However, hydrogenated bisphenol A is a secondary alcohol, has low hydroxyl activity, and is difficult to esterify with terephthalic acid and polymerize. Therefore, hydrogenated bisphenol A is mainly applied to epoxy resin, paint, polycaprolactone and the like at present and is rarely applied to modification of PETG copolyester. Therefore, the hydrogenated bisphenol A is subjected to esterification and polycondensation reactions, and a catalyst is required. At present, catalysts for industrially producing PETG are mainly monomer catalysts such as tetrabutyl titanate, titanium glycol, antimony glycol and the like, but the conventional titanium-based catalysts have more side reactions, poor selectivity and other factors, and cannot meet the conditions of esterification and polycondensation reactions of hydrogenated bisphenol A applied to PETG. In addition, in the esterification and polycondensation reaction processes, the catalyst is hydrolyzed, so that metal elements such as titanium or antimony are reduced, the color of the PETG product is influenced, and the overall quality of the PETG product is finally influenced.
CN107513154a discloses a titanium-based polyester catalyst and a method for producing copolyester by using titanate, ethylene glycol and phosphate to react to obtain a titanium-based catalyst, and then polymerizing the titanium-based catalyst with terephthalic acid, ethylene glycol, 1, 4-cyclohexanedimethanol and hydrogenated bisphenol a to obtain a copolyester, wherein the viscosity and chromaticity of the product are improved, but the adopted catalyst is still a titanium-based monomer catalyst, and although the solubility in ethylene glycol is improved, the occurrence of certain side reactions is reduced, the catalyst is still hydrolyzed, the selectivity of the catalyst is low, and the color of PETG products is disqualified; and hydrogenated bisphenol A is copolymerized with all monomers at one time, so that the oligomer is decomposed by reverse reaction.
CN113929886a discloses a long chain branched PETG copolyester and a preparation method thereof, and the introduction of a branched structure provides entanglement interaction between chains for linear polyester material, so that the problems of low melt strength and the like of the traditional linear polyester are improved. However, the catalyst is tetrabutyl titanate, isobutyl titanate and the like, and the problems of poor product color, more byproducts and the like caused by the hydrolysis of the catalyst are still avoided.
CN115785419a discloses a modified PETG copolyester, a preparation method and a preparation method of foamed particles thereof, which adopt esterification reaction, firstly prepare an oligomer a and an oligomer B by adopting carboxyl-terminated organosiloxane and tetrabutyl titanate catalyst, and then perform polycondensation by using platinum and chloroplatinic acid catalyst to obtain the modified PETG, although the foamed particles have high foaming multiplying power and uniform foam cells, the foaming performance is improved, but the glass transition temperature is still lower, and the modified PETG is difficult to be applied to heat resistant performance equipment.
Disclosure of Invention
The invention aims to overcome the defects in the prior art and provide a method for preparing modified PETG copolyester by using a quaternary ammonium titanium/zirconium chelate catalyst, wherein the catalyst has high selectivity and hydrolysis resistance, and the prepared PETG copolyester has bright color, good yellowing resistance, good heat resistance and good mechanical property.
The method for preparing the modified PETG copolyester by adopting the quaternary ammonium titanium/zirconium chelate catalyst comprises the following steps:
(1) Mixing terephthalic acid, 1, 4-cyclohexanedimethanol and ethylene glycol, and carrying out esterification reaction, wherein the water yield is more than 95wt.% of theoretical value, so as to obtain an oligomer a;
(2) Mixing hydrogenated bisphenol A with ethylene glycol, dissolving, adding terephthalic acid and a catalyst, pulping, and carrying out esterification reaction, wherein the water yield is more than 95wt.% of theoretical value, so as to obtain an oligomer b;
(3) Polycondensation reaction: mixing the oligomer a with the oligomer b, an antioxidant and a catalyst, carrying out a step-type vacuum pre-polycondensation reaction, and then carrying out a final polycondensation reaction to obtain a modified PETG product;
the preparation method of the catalyst in the step (2) and the step (3) comprises the following steps: dissolving 2, 3-dihydroxypropyl-trimethyl ammonium chloride in N, N-dimethylacetamide, adding tetrabutyl titanate or tetrabutyl zirconate, stirring for 10-30 min, refluxing at 50-80 ℃ for 0.5-2 h, filtering, washing, and freeze-drying at-10-20 ℃ for 0.5-2 d to obtain a quaternary ammonium titanium/zirconium chelate catalyst; the molar ratio of tetrabutyl titanate or tetrabutyl zirconate to 2, 3-dihydroxypropyl-trimethyl ammonium chloride is (1-1.3) (1.8-2.5).
The structural formulas of the catalysts in the step (2) and the step (3) are as follows:
wherein M is titanium or zirconium.
In the step (1), the mol ratio of terephthalic acid to 1, 4-cyclohexanedimethanol to glycol is 5 (2-4) (3-10); in the step (2), the mol ratio of terephthalic acid to hydrogenated bisphenol A to glycol is 5 (1-2) (8-15); the molar ratio of the hydrogenated bisphenol A in the step (2) to the 1, 4-cyclohexanedimethanol in the step (1) is from 0.5 to 0.72:1.
The catalyst in the step (2) is added in an amount of 2 to 10ppm based on the mass of the terephthalic acid in the step (2).
The catalyst in the step (3) is added in an amount of 3 to 8ppm based on the total mass of the terephthalic acid in the step (1) and the step (2).
The esterification reaction temperature of the step (1) is 240-250 ℃, the reaction pressure is 200-300 KPa, and the reaction time is 90-120 min.
The esterification reaction temperature of the step (2) is 250-270 ℃, the reaction pressure is 250-350 KPa, and the reaction time is 180-210 min.
The step vacuum pre-polycondensation reaction temperature of the step (3) is 270-290 ℃, and the step vacuum pre-polycondensation reaction process is as follows: firstly, the absolute pressure is adjusted to be 90-100 KPa for 5-10 min, the absolute pressure is adjusted to be 55-75 KPa for 10-15 min, the absolute pressure is adjusted to be 5-9 KPa for 10-15 min, the absolute pressure is adjusted to be 3-5 KPa for 10-15 min, the absolute pressure is adjusted to be 1-2 KPa for 10-15 min, and finally the absolute pressure is adjusted to be 0.4-0.5 KPa and then the absolute pressure is adjusted to be 5-10 min.
The final polycondensation reaction temperature is 280-300 ℃, the absolute pressure of the final polycondensation reaction is less than 70Pa, and the final polycondensation reaction time is 200-230 min.
The adding amount of the antioxidant in the step (3) is 0.05 to 0.2 per mill of the total mass of the terephthalic acid in the step (1) and the step (2).
The antioxidant is one or more of pentaerythritol tetra [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ], tri (2, 4-di-tert-butylphenyl) phosphite, n-stearyl beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate and carbon-based-4, 4-diisobutylene-fatty alcohol-phosphate chelate compound polymer.
Specifically, the method for preparing the modified PETG copolyester by adopting the quaternary ammonium titanium/zirconium chelate catalyst comprises the following steps:
(1) Preparing a catalyst: dissolving 2, 3-dihydroxypropyl-trimethyl ammonium chloride in N, N-dimethylacetamide, adding tetrabutyl titanate or tetrabutyl zirconate, stirring for 10-30 min, refluxing at 50-80 ℃ for 0.5-2 h, gradually generating white precipitate in the solution, filtering the solvent after the reaction, washing with N-heptane, and freeze-drying at-10-20 ℃ for 0.5-2 d to obtain a quaternary ammonium titanium/zirconium chelate catalyst; the molar ratio of tetrabutyl titanate or tetrabutyl zirconate to 2, 3-dihydroxypropyl-trimethyl ammonium chloride is (1-1.3) (1.8-2.5). The reaction formula is as follows:
。
(2) Adding terephthalic acid, 1, 4-cyclohexanedimethanol and ethylene glycol into a reaction kettle I, mixing (3-10) according to the mol ratio of 5 (2-4), lifting a kettle Wen Zhujian to 240-250 ℃, lifting the pressure in the kettle to 200-300 KPa, at the moment, starting water outlet in the esterification stage when the temperature of the top of the esterification tower is 80-105 ℃, and starting water outlet for 90-100 min, and ending the esterification reaction when the temperature of the top of the esterification tower is reduced to 79-90 ℃, wherein the water outlet is more than 95wt.% of theoretical value, thus obtaining the oligomer a.
(3) Adding hydrogenated bisphenol A and ethylene glycol into a reaction kettle II, mixing and dissolving, adding 2-10 ppm of catalyst for pulping, lifting the kettle Wen Zhujian to 250-270 ℃, lifting the pressure in the kettle to 250-350 KPa, at this moment, starting water outlet in the esterification stage at 100-110 ℃, and starting water outlet for 170-200 min, and ending the esterification reaction when the temperature at the top of the kettle begins to drop to 80-90 ℃, wherein the water yield is more than 95wt.% of theoretical value, thus obtaining the oligomer b.
(4) Polycondensation reaction: adding an oligomer a, an oligomer b and an antioxidant into a reaction kettle III, stirring for 10-20 min, adding a catalyst, pre-condensing at 270-290 ℃, starting to establish vacuum, firstly adjusting the absolute pressure to 90-100 KPa for 5-10 min, adjusting the absolute pressure to 55-75 KPa for 10-15 min, adjusting the absolute pressure to 5-9 KPa for 10-15 min, adjusting the absolute pressure to 3-5 KPa for 10-15 min, adjusting the absolute pressure to 1-2 KPa for 10-15 min, finally adjusting the absolute pressure to 0.4-0.5 KPa, then, stopping for 5-10 min, starting the full vacuum, entering the final polycondensation stage, and performing final polycondensation at 280-300 ℃ and absolute pressure <70Pa for 200-230 min to obtain the modified PETG product.
The structural formula of the modified PETG copolyester is shown as follows, wherein a, b and c are the polymerization degree of the modified PETG, a is (60-140), b is (130-280), and c is (270-470).
。
The method for preparing the modified PETG copolyester adopts the quaternary ammonium titanium/zirconium chelate catalyst, which is formed by the reaction of tetrabutyl titanate or tetrabutyl zirconate and quaternary ammonium salt, takes the quaternary ammonium salt as a ligand, has a titanium chelate structure with double five-membered rings, has good stability and good hydrolysis resistance, and in addition, quaternary ammonium salt groups in the catalyst increase the steric hindrance of the chelate structure, prevent water molecules from attacking titanium oxygen bonds, and ensure that the catalyst cannot be hydrolyzed in the esterification and polycondensation reaction processes.
The steric hindrance effect of the quaternary ammonium salt and the titanium chelate in the catalyst prevents the quaternary ammonium salt group from decomposing under the action of high temperature, the catalytic selectivity of the quaternary ammonium salt group is superior to that of the titanium group, the overall selectivity of the catalyst is improved, and the generation of byproducts is reduced.
In the esterification process, terephthalic acid in a reaction kettle II is firstly subjected to esterification reaction with ethylene glycol to generate ethylene terephthalate, nitrogen positive ions of quaternary ammonium salt groups of the added catalyst have lone pair electrons, nucleophilic attack on carbonyl groups in ester groups, an amide positive ion active transition state compound is formed after combination, phenolic hydroxyl groups of bisphenol A are hydrogenated to nucleophilic attack on carbonyl groups in amide positive ions, a hydrogenated bisphenol A terephthalate oligomer is obtained, carbon-oxygen double bonds on the carbonyl groups are broken by titanium groups of the catalyst and then form bonds with titanium to form coordination compounds, and the coordination effect enhances the electropositivity of carbonyl carbon atoms and the electronegativity of carbonyl oxygen atoms, so that the polymerization reaction rate is accelerated. The catalyst adopts quaternary ammonium salt and titanium to form a double-catalytic-function system, and the addition amount is only 3-8 ppm of the total mass of terephthalic acid, so that the problem of catalyst residue is greatly reduced. And the high activity of the quaternary ammonium titanium chelate catalyst also enables the esterification reaction of hydrogenated bisphenol A and terephthalic acid to be carried out normally.
The invention adopts the separate esterification step, solves the problem of difficult reaction of hydrogenated bisphenol A and terephthalic acid, ensures the simultaneity of polycondensation reaction and prevents the oligomer from reverse reaction decomposition. And the esterification reaction of hydrogenated bisphenol A and terephthalic acid is difficult to carry out, so that the reaction of 1, 4-cyclohexanedimethanol and terephthalic acid is not influenced. And simultaneously adding the oligomer a obtained from the reaction kettle I and the oligomer b obtained from the reaction kettle II into the reaction kettle III for polycondensation reaction, and improving the glass transition temperature of the modified PETG copolyester.
Compared with the prior art, the invention has the following beneficial effects:
(1) The quaternary ammonium titanium/zirconium chelate catalyst adopted in the method for preparing the modified PETG copolyester has good hydrolysis resistance, ensures that the catalyst cannot be hydrolyzed in the esterification and polycondensation reaction processes, has better hydrolysis stability, and greatly reduces the influence of catalyst hydrolysis on the color of PETG products.
(2) The method for preparing the modified PETG copolyester improves the overall selectivity of the quaternary ammonium titanium/zirconium chelate catalyst and reduces the generation of byproducts.
(3) According to the method for preparing the modified PETG copolyester, the adopted catalyst is a system with double catalytic functions formed by quaternary ammonium salt and titanium/zirconium, so that the synergistic catalytic effect is achieved, the stability is good, the use amount of the catalyst is reduced, and the residual problem of the catalyst is reduced.
(4) According to the method for preparing the modified PETG copolyester, after the steps of esterification and the synergistic effect of adding hydrogenated bisphenol A are adopted, the glass transition temperature Tg of the obtained modified PETG copolyester is increased from 78 ℃ to 95 ℃, the modified PETG copolyester has good mechanical properties and heat resistance, and the downstream application of heat-resistant equipment and medical appliances is better met.
Detailed Description
The invention will be further illustrated with reference to specific examples.
The reagents used in the following examples and comparative examples were all commercially available products.
Example 1
The method for preparing the modified PETG copolyester by adopting the quaternary ammonium titanium chelate catalyst comprises the following steps:
(1) Preparing a catalyst: dissolving 0.0095mol of 2, 3-dihydroxypropyl-trimethyl ammonium chloride in N, N-dimethyl acetamide, adding 0.005mol of tetrabutyl titanate, stirring for 20min, refluxing at 75 ℃ for 1h, gradually generating white precipitate in the solution, filtering out the solvent N, N-dimethyl acetamide after the reaction is finished, washing with N-heptane, and freeze-drying at-20 ℃ for 1d to obtain the quaternary ammonium salt titanium chelate catalyst.
(2) 830g of terephthalic acid, 432g of 1, 4-cyclohexanedimethanol and 372g of ethylene glycol are added into a reaction kettle I, the kettle Wen Zhujian is raised to 245 ℃, the pressure in the kettle is raised to 250KPa, at the moment, the temperature of the top of the esterification tower is 100 ℃, water is discharged from the esterification stage for 90min, the temperature of the top of the esterification tower is reduced to 80 ℃, the esterification reaction is finished, and the water yield is more than 95wt.% of theoretical value, so as to obtain the oligomer a.
(3) Adding 360g of hydrogenated bisphenol A and 744g of ethylene glycol into a reaction kettle II, mixing and dissolving, adding 830g of terephthalic acid and 0.029g of the quaternary ammonium salt titanium chelate catalyst prepared in the step (1) and pulping for 10min, then lifting the kettle Wen Zhujian to 260 ℃, raising the pressure in the kettle to 300KPa, wherein the temperature at the top of the kettle is 100 ℃, starting water outlet in the esterification stage, and discharging water for 180min, and when the temperature at the top of the kettle begins to drop to 82 ℃, finishing the esterification reaction, and controlling the water outlet to be more than 95wt.% of theoretical value, thus obtaining the oligomer b.
(4) Polycondensation reaction: adding oligomer a, oligomer b and 0.083g of pentaerythritol tetrakis [ beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionate ] into a reaction kettle III, stirring for 10min, adding 0.029g of the quaternary ammonium titanium chelate catalyst in the step (1), pre-polymerizing at 275 ℃, starting to establish vacuum, regulating the absolute pressure in the reaction kettle to 95KPa, keeping for 10min, regulating to 65KPa, keeping for 10min, keeping for 15min, regulating to 4.35KPa, keeping for 15min, regulating to 1.49KPa, keeping for 10min, keeping for 0.468KPa, starting the full vacuum, entering the final polycondensation stage, keeping for 290 ℃ and keeping for 210min, thus obtaining the modified PETG product.
Example 2
The method for preparing the modified PETG copolyester by adopting the quaternary ammonium titanium chelate catalyst comprises the following steps:
(1) Preparing a catalyst: dissolving 0.0075mol of 2, 3-dihydroxypropyl-trimethyl ammonium chloride in N, N-dimethylacetamide, adding 0.0039mol of tetrabutyl titanate, stirring for 30min, refluxing at 80 ℃ for 1h, gradually generating white precipitate in the solution, filtering the solvent after the reaction is finished, washing with N-heptane, and freeze-drying at-15 ℃ for 1.5d to obtain the quaternary ammonium salt titanium chelate catalyst.
(2) 830g of terephthalic acid, 360g of 1, 4-cyclohexanedimethanol and 310g of ethylene glycol are added into a reaction kettle I, the kettle Wen Zhujian is raised to 248 ℃, the pressure in the kettle is raised to 320KPa, at the moment, the temperature of the top of the esterification kettle is 100 ℃, water is discharged from the esterification stage for 110min, and when the temperature of the top of the esterification kettle is reduced to 80 ℃, the esterification reaction is finished, and the water yield is more than 95wt.% of theoretical value, so as to obtain the oligomer a.
(3) Adding 432g of hydrogenated bisphenol A and 620g of ethylene glycol into a reaction kettle II, mixing and dissolving, adding 830g of terephthalic acid and 0.035g of the quaternary ammonium salt titanium chelate catalyst prepared in the step (1) to pulp for 10min, then lifting the kettle Wen Zhujian to 255 ℃, lifting the pressure in the kettle to 320KPa, wherein the temperature at the top of the kettle is 105 ℃, starting water outlet in the esterification stage, and discharging water for 200min, and when the temperature at the top of the kettle begins to drop to 80 ℃, finishing the esterification reaction, and controlling the water outlet to be more than 95wt.% of theoretical value, thus obtaining the oligomer b.
(4) Polycondensation reaction: adding oligomer a, oligomer b and 0.166g of beta- (3, 5-di-tert-butyl-4-hydroxyphenyl) propionic acid n-octadecyl ester into a reaction kettle III, stirring for 10min, adding 0.032g of the quaternary ammonium salt titanium chelate catalyst prepared in the step (1), pre-polymerizing at 280 ℃, starting to establish vacuum, regulating the absolute pressure in the reaction kettle to 98KPa for 8min, regulating the absolute pressure to 69KPa for 13min, regulating the absolute pressure to 8.2KPa for 12min, regulating the absolute pressure to 3.5KPa for 13min, regulating the absolute pressure to 1.4KPa for 15min, regulating the absolute pressure to 0.45KPa finally, stopping for 8min, starting the full vacuum, entering a final polycondensation stage, regulating the absolute pressure in the kettle to 58Pa at 285 ℃, and performing final polycondensation reaction for 230min to obtain the modified PETG product.
Example 3
The method for preparing the modified PETG copolyester by adopting the quaternary ammonium salt zirconium chelate catalyst comprises the following steps:
(1) Preparing a catalyst: dissolving 0.01mol of 2, 3-dihydroxypropyl-trimethyl ammonium chloride in N, N-dimethylacetamide, adding 0.0055mol of tetrabutyl zirconate, stirring for 25min, refluxing at 80 ℃ for 2h, gradually generating white precipitate in the solution, filtering the solvent after the reaction, washing with N-heptane, and freeze-drying at-10 ℃ for 2d to obtain the quaternary ammonium salt zirconium chelate catalyst.
(2) Adding 850g of terephthalic acid, 288g of 1, 4-cyclohexanedimethanol and 248g of ethylene glycol into a reaction kettle I, mixing, lifting the kettle Wen Zhujian to 240 ℃, lifting the pressure in the kettle to 200MPa, starting water outlet in the esterification stage when the temperature of the top of the esterification kettle is 102 ℃, and starting water outlet for 95min, and ending the esterification reaction when the temperature of the top of the esterification kettle is reduced to 85 ℃, wherein the water outlet is more than 95wt.% of theoretical value, thus obtaining the oligomer a.
(3) Adding 240g of hydrogenated bisphenol A and 496g of ethylene glycol into a reaction kettle II, mixing and dissolving, adding 830g of terephthalic acid and 0.0316g of the quaternary ammonium salt zirconium chelate catalyst prepared in the step (1), pulping for 10min, then lifting the kettle Wen Zhujian to 250 ℃ and raising the pressure in the kettle to 250KPa, wherein the temperature of the top of the kettle is 110 ℃, starting water outlet in the esterification stage, and discharging water for 180min, and when the temperature of the top of the kettle begins to drop to 85 ℃, finishing the esterification reaction, and controlling the water yield to be more than 95wt.% of theoretical value, thus obtaining the oligomer b.
(4) Polycondensation reaction: adding oligomer a, oligomer b and 0.199g of tris [ 2.4-di-tert-butylphenyl ] phosphite into a reaction kettle III, stirring for 10min, adding 0.025g of the quaternary ammonium salt zirconium chelate catalyst prepared in the step (1), pulping for 10min, adding 290 ℃ for pre-polycondensation reaction, starting to establish vacuum, regulating the absolute pressure in the reaction kettle to 100KPa, staying for 5min, regulating the absolute pressure to 55KPa, staying for 15min, regulating the absolute pressure to 5KPa, staying for 10min, regulating the absolute pressure to 3KPa, staying for 12min, regulating the absolute pressure to 1KPa, staying for 10min, finally regulating the absolute pressure to 0.4KPa, staying for 5min, starting the full vacuum, entering a final polycondensation stage, and carrying out final polycondensation reaction for 200min at the final polycondensation temperature of 300 ℃ under the absolute pressure of 55Pa in the kettle to obtain a modified PETG product.
Example 4
The method for preparing the modified PETG copolyester by adopting the quaternary ammonium salt zirconium chelate catalyst comprises the following steps:
(1) Preparing a catalyst: dissolving 0.0111 mol of 2, 3-dihydroxypropyl-trimethyl ammonium chloride in N, N-dimethylacetamide, adding 0.006mol of tetrabutyl zirconate, stirring for 10min, refluxing at 50 ℃ for 0.5h, gradually generating white precipitate in the solution, filtering the solvent after the reaction is finished, washing with N-heptane, and freeze-drying at-15 ℃ for 0.5d to obtain the quaternary ammonium salt zirconium chelate catalyst.
(2) 830g of terephthalic acid, 576g of 1, 4-cyclohexanedimethanol and 500g of ethylene glycol are added into a reaction kettle I for mixing, the kettle Wen Zhujian is lifted to 250 ℃, the pressure in the kettle is raised to 300KPa, at the moment, when the temperature of the top of the esterification tower is 100 ℃, water starts to be discharged from the esterification stage, the water is discharged for 100min, when the temperature of the top of the esterification tower starts to be reduced to 83 ℃, the esterification reaction is finished, and the water yield is more than 95wt.% of theoretical value, so as to obtain the oligomer a.
(3) Adding 480g of hydrogenated bisphenol A and 931g of ethylene glycol into a reaction kettle II, mixing and dissolving, adding 830g of terephthalic acid and 0.006g of the quaternary ammonium salt zirconium chelate catalyst prepared in the step (1), pulping for 10min, lifting the kettle Wen Zhujian to 270 ℃, lifting the pressure in the kettle to 350KPa, wherein the temperature at the top of the kettle is 110 ℃, starting water outlet in the esterification stage, and discharging water for 210min, and when the temperature at the top of the kettle begins to drop to 90 ℃, finishing the esterification reaction, and controlling the water outlet to be more than 95wt.% of theoretical value, thus obtaining the oligomer b.
(4) Polycondensation reaction: adding an oligomer a, an oligomer b and 0.332g of a carbon-based-4, 4-diisofork-fatty alcohol-phosphate chelate polymer into a reaction kettle III, stirring for 10min, adding 0.0095g of the quaternary ammonium salt zirconium chelate catalyst prepared in the step (1), performing pre-polycondensation reaction at 270 ℃, starting to establish vacuum, regulating the absolute pressure in the reaction kettle to 90KPa, staying for 6min, then regulating the absolute pressure to 60KPa, staying for 14min, regulating the absolute pressure to 6.2KPa, staying for 13min, regulating the absolute pressure to 4.5KPa, staying for 12min, regulating the absolute pressure to 1.6KPa, staying for 15min, finally regulating the absolute pressure to 0.5KPa, staying for 8min, starting the full vacuum, entering a final polycondensation stage, and performing final polycondensation reaction for 220min at the absolute pressure of 68Pa in the kettle to obtain a modified PETG product.
Comparative example 1
The comparative example was identical to the esterification reaction and polycondensation reaction of example 1, except that modification was performed without adding hydrogenated bisphenol A, only PETG copolyester was obtained.
Comparative example 2
The preparation method of the modified PETG copolyester comprises the following steps:
(1) The catalyst was prepared in the same manner as in example 1.
(2) 1660g of terephthalic acid, 360g of 1,4 cyclohexane dimethanol, 432g of hydrogenated bisphenol A, 930g of ethylene glycol and 0.035g of the quaternary ammonium salt titanium chelate catalyst prepared in the step (1) are added into a reaction kettle I, the temperature of the reaction kettle is raised to 255 ℃, the pressure of the reaction kettle is raised to 320KPa, at the moment, the esterification stage starts to discharge water when the temperature of the top of the esterification tower is 100 ℃, the water is discharged for 200min, and when the temperature of the top of the esterification tower starts to be lowered to 80 ℃, the esterification reaction is finished, and the water yield is more than 95wt.% of theoretical value, so as to obtain the esterified oligomer.
(3) Adding 0.032g of the quaternary ammonium titanium chelate catalyst prepared in the step (1) into a reaction kettle, stirring for 10min, adding 0.199g of tris [ 2.4-di-tert-butylphenyl ] phosphite, performing pre-polycondensation reaction at 270 ℃, establishing vacuum for pre-polycondensation, and performing final polycondensation reaction at 280 ℃ under the absolute pressure of 68Pa for 220min to obtain the co-esterification modified PETG product.
Comparative example 3
The comparative example was the same as the esterification reaction and polycondensation reaction of example 1, except that the polycondensation reaction catalyst was replaced with tetrabutyl titanate from a quaternary ammonium titanium chelate, and the titanium content of the catalyst added was the same as example 1.
Comparative example 4
The comparative example was the same as the esterification reaction and polycondensation reaction of example 1 except that the catalyst for the esterification reaction of hydrogenated bisphenol A was replaced with tetrabutyl titanate by a quaternary ammonium titanium chelate, the catalyst for the polycondensation reaction was also replaced with tetrabutyl titanate by a quaternary ammonium titanium chelate, and the titanium content of the catalyst added was the same as in example 1.
The intrinsic viscosity, carboxyl end group content, mechanical properties, glass transition temperature and chromaticity of the PETG copolyesters prepared in examples 1-4 and comparative examples 1-4 were tested, and the test results are shown in Table 2 below. Firstly, pretreating the prepared modified PETG copolyester, drying the granules in a vacuum drying oven, continuously drying at 70 ℃ for 5 hours, and then testing.
The testing method comprises the following steps:
(1) Intrinsic viscosity test
According to the national standard GB/T14190-2017 test method for fiber grade polyester chips- (PET), a capillary viscosity method is adopted, and phenol is used as a solvent: 1, 2-tetrachloroethane=1:1 (mass ratio), and was tested using a black viscometer.
(2) Terminal carboxyl group content test
According to the test method in the national standard GB/T14190 2008. The mixture is phenol-chloroform with the volume ratio of 2:3, the standard titration solution is potassium hydroxide-benzyl alcohol with the concentration of 0.01mol/l, the bromophenol blue indicator concentration of 0.2 percent, and the sample is prepared: 0.5g of the sample was dissolved in 25mL of a phenol-chloromethane mixed solvent, and the alkali titration operation was performed.
(3) Mechanical Property (impact Strength) test
The injection molding test sample is carried out according to the specification of GB/T17037.1-1997, and the B1 type test sample conforming to the specification of GB/T1040.2-2006 is prepared by using the B type mold in GB/T17037.1-1997. The test sample should be according to ISO 2818:1994 was machined from sheet stock using a-type notches. The machined surface of the unnotched test sample should not be in tension during testing.
Sample preparation conditions: the FANUC ROBOSHOT alpha-S100 iA Japan Fanac full-electric injection molding machine and screw injection machine process are adopted. The condition of the sample was adjusted according to the specification of GB/T2918-1998, the condition of the condition adjustment is 23 ℃ +/-2 ℃ and the adjustment time is 48 hours, the test is carried out under the standard environment specified by GB/T2918-1998, the temperature of the environment is 23 ℃ +/-2 ℃ and the relative humidity is 50% +/-10%.
Sample preparation conditions: the process parameters are shown in Table 1 using FANUC ROBOSHOT alpha-S100 iA Japan Faonaceae all-electric injection molding machine and screw injection machine.
Table 1 technological parameters of injection molding machine
(4) Glass transition temperature
Glass transition temperature (Tg) testing of the modified PETG copolyesters was performed using Discovery DSC 250. Test conditions: 8-10mg of sample is weighed, and the temperature is 50-300 ℃ in nitrogen atmosphere, and the heating speed is 10 ℃/min.
(5) Colorimetric test
Test conditions were used with the model alice X-Rite Ci 7600: the test was performed using a 25mm aperture, reflection mode.
Table 2 test results
As can be seen from Table 2, the addition of hydrogenated bisphenol A modified PETG copolyester in examples 1-4 of the present invention provides a significant increase in glass transition temperature (Tg). Examples 1-4 employ the split esterification form to give PETG copolyesters with a higher degree of reaction, lower acid number and better mechanical properties than comparative example 2. In examples 1-4, the titanium/zirconium chelate catalyst of quaternary ammonium salt is adopted in the esterification and polycondensation stages, and compared with comparative example 3, the titanium/zirconium chelate catalyst of quaternary ammonium salt can improve the L value of the PETG copolyester, reduce the a and b values, and the obtained PETG copolyester is brighter, more transparent and lighter in color. Compared with comparative example 4, the quaternary ammonium titanium/zirconium chelate catalyst can effectively catalyze the esterification reaction of hydrogenated bisphenol A, and the obtained PETG copolyester has the intrinsic viscosity reaching the general level and more stable mechanical properties.

Claims (10)

1. A method for preparing modified PETG copolyester by adopting a quaternary ammonium titanium/zirconium chelate catalyst is characterized by comprising the following steps: the method comprises the following steps:
(1) Mixing terephthalic acid, 1, 4-cyclohexanedimethanol and ethylene glycol, and carrying out esterification reaction, wherein the water yield is more than 95wt.% of theoretical value, so as to obtain an oligomer a;
(2) Mixing hydrogenated bisphenol A with ethylene glycol, dissolving, adding terephthalic acid and a catalyst, pulping, and carrying out esterification reaction, wherein the water yield is more than 95wt.% of theoretical value, so as to obtain an oligomer b;
(3) Polycondensation reaction: mixing the oligomer a with the oligomer b, an antioxidant and a catalyst, carrying out a step-type vacuum pre-polycondensation reaction, and then carrying out a final polycondensation reaction to obtain a modified PETG product;
the preparation method of the catalyst in the step (2) and the step (3) comprises the following steps: dissolving 2, 3-dihydroxypropyl-trimethyl ammonium chloride in N, N-dimethylacetamide, adding tetrabutyl titanate or tetrabutyl zirconate, stirring for 10-30 min, refluxing at 50-80 ℃ for 0.5-2 h, filtering, washing, and freeze-drying at-10-20 ℃ for 0.5-2 d to obtain a quaternary ammonium titanium/zirconium chelate catalyst; the molar ratio of tetrabutyl titanate or tetrabutyl zirconate to 2, 3-dihydroxypropyl-trimethyl ammonium chloride is (1-1.3) (1.8-2.5).
2. The method for preparing the modified PETG copolyester by using a quaternary ammonium titanium/zirconium chelate catalyst as claimed in claim 1, wherein the method comprises the following steps: the structural formulas of the catalysts in the step (2) and the step (3) are as follows:
wherein M is titanium or zirconium.
3. The method for preparing the modified PETG copolyester by using a quaternary ammonium titanium/zirconium chelate catalyst as claimed in claim 1, wherein the method comprises the following steps: in the step (1), the mol ratio of terephthalic acid to 1, 4-cyclohexanedimethanol to glycol is 5 (2-4) (3-10); in the step (2), the mol ratio of terephthalic acid to hydrogenated bisphenol A to glycol is 5 (1-2) (8-15); the molar ratio of the hydrogenated bisphenol A in the step (2) to the 1, 4-cyclohexanedimethanol in the step (1) is from 0.5 to 0.72:1.
4. The method for preparing the modified PETG copolyester by using a quaternary ammonium titanium/zirconium chelate catalyst as claimed in claim 1, wherein the method comprises the following steps: the catalyst in the step (2) is added in an amount of 2 to 10ppm based on the mass of the terephthalic acid in the step (2).
5. The method for preparing the modified PETG copolyester by using a quaternary ammonium titanium/zirconium chelate catalyst as claimed in claim 1, wherein the method comprises the following steps: the catalyst in the step (3) is added in an amount of 3 to 8ppm based on the total mass of the terephthalic acid in the step (1) and the step (2).
6. The method for preparing the modified PETG copolyester by using a quaternary ammonium titanium/zirconium chelate catalyst as claimed in claim 1, wherein the method comprises the following steps: the esterification reaction temperature of the step (1) is 240-250 ℃, the reaction pressure is 200-300 KPa, and the reaction time is 90-120 min.
7. The method for preparing the modified PETG copolyester by using a quaternary ammonium titanium/zirconium chelate catalyst as claimed in claim 1, wherein the method comprises the following steps: the esterification reaction temperature of the step (2) is 250-270 ℃, the reaction pressure is 250-350 KPa, and the reaction time is 180-210 min.
8. The method for preparing the modified PETG copolyester by using a quaternary ammonium titanium/zirconium chelate catalyst as claimed in claim 1, wherein the method comprises the following steps: the step vacuum pre-polycondensation reaction temperature of the step (3) is 270-290 ℃, and the step vacuum pre-polycondensation reaction process is as follows: firstly, the absolute pressure is adjusted to be 90-100 KPa for 5-10 min, the absolute pressure is adjusted to be 55-75 KPa for 10-15 min, the absolute pressure is adjusted to be 5-9 KPa for 10-15 min, the absolute pressure is adjusted to be 3-5 KPa for 10-15 min, the absolute pressure is adjusted to be 1-2 KPa for 10-15 min, and finally the absolute pressure is adjusted to be 0.4-0.5 KPa and then the absolute pressure is adjusted to be 5-10 min.
9. The method for preparing the modified PETG copolyester by using a quaternary ammonium titanium/zirconium chelate catalyst as claimed in claim 1, wherein the method comprises the following steps: the final polycondensation reaction temperature is 280-300 ℃, the absolute pressure of the final polycondensation reaction is less than 70Pa, and the final polycondensation reaction time is 200-230 min.
10. The method for preparing the modified PETG copolyester by using a quaternary ammonium titanium/zirconium chelate catalyst as claimed in claim 1, wherein the method comprises the following steps: the adding amount of the antioxidant in the step (3) is 0.05 to 0.2 per mill of the total mass of the terephthalic acid in the step (1) and the step (2).
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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3056818A (en) * 1955-10-13 1962-10-02 Goodrich Co B F Titanium and zirconium esterification catalysts
CN115785409A (en) * 2022-11-22 2023-03-14 中国石油化工股份有限公司 Titanium catalyst and preparation method thereof

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3056818A (en) * 1955-10-13 1962-10-02 Goodrich Co B F Titanium and zirconium esterification catalysts
CN115785409A (en) * 2022-11-22 2023-03-14 中国石油化工股份有限公司 Titanium catalyst and preparation method thereof

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