Catalyst for synthesizing PBT resin, preparation method of catalyst, PBT resin and preparation method of PBT resin

Abstract

The invention relates to a catalyst for synthesizing PBT (Polybutylene Terephthalate) resin, a preparation method of the catalyst, the PBT resin and a preparation method of the PBT resin. The preparation method of the catalyst for PBT resin synthesis comprises the following steps: carrying out transesterification on a titanium compound A and dihydric alcohol C to obtain a product 1; adding the product 1 into 1, 4-butanediol, then adding a phosphorus compound B, a metal compound D, an aliphatic organic compound E, aliphatic organic polyether F and a blue toner G, reacting at 120-140 DEG C for 3.5-4.5 hours, and diluting with 1, 4-butanediol to obtain a homogeneous-phase liquid titanium polyester catalyst, namely the catalyst for synthesizing the PBT resin. According to the catalyst for synthesizing the PBT resin, the preparation method of the catalyst, the PBT resin and the preparation method of the PBT resin, the performance of the PBT resin is improved, meanwhile, the consumption of raw materials in the synthesis of the PBT resin can be reduced, the cost is reduced, and the catalyst is more suitable for industrial popularization.

Description

Technical Field

[0001] The invention belongs to the technical field of polyesters, and specifically relates to a catalyst for synthesizing a high-color-value PBT resin and a preparation method thereof, and a high-color-value PBT resin and a preparation method thereof. Background Art

[0002] Polybutylene terephthalate (PBT) is a thermoplastic polyester synthesized by esterification and polycondensation of terephthalic acid (PTA) or methyl terephthalate and butanediol (BDO). It has the properties of easy processing, good high temperature resistance, moisture resistance, oil resistance, chemical resistance, fatigue resistance, etc. It is widely used in various fields such as automobiles, machinery, instruments, electronics and electrical, household appliances, aerospace, textiles and civil use.

[0003] There are two main synthesis processes for PBT resin: transesterification and direct esterification. Initially, because the purity of the raw material PTA was difficult to meet the standard, the production was mainly based on the transesterification method. With the continuous improvement of the purity of PTA products and the continuous development of catalysts, the direct esterification method has developed into the main method of PBT production. At present, the commonly used catalysts for PBT synthesis are mainly organic titanate compounds, such as tetraethyl titanate, tetrabutyl titanate, tetraisopropyl titanate, etc., but the PBT resin products prepared using pure titanium catalysts have high carboxyl content, poor hydrolysis resistance, hue deteriorates with the extension of production time, unstable elongation at break, low notch impact strength, poor spinning quality and other related problems.

[0004] In view of this, the present invention provides a novel catalyst for synthesizing a high-color value PBT resin and a preparation method, a high-color value PBT resin and a preparation method, which can prepare a PBT resin with good product hue, low carboxyl content, strong hydrolysis resistance, stable elongation at break, high notched impact strength and excellent quality. Summary of the invention

[0005] The first object of the present invention is to provide a method for preparing a catalyst for synthesizing PBT resin, which is simple.

[0006] In order to achieve the above purpose, the technical solution adopted is:

[0007] A method for preparing a catalyst for PBT resin synthesis, characterized in that the preparation method comprises:

[0008] Transesterify the titanium compound A with the diol C to obtain product 1;

[0009] The product 1 is added to 1,4-butanediol, and then a phosphorus compound B, a metal compound D, an aliphatic organic compound E, an aliphatic organic polyether F, and a blue colorant G are added. After reacting at 120-140°C for 3.5-4.5 hours, the product 1 is diluted with 1,4-butanediol to obtain a homogeneous liquid titanium-based polyester catalyst, i.e., the catalyst for PBT resin synthesis.

[0010] Further, the temperature of the transesterification reaction is 80-120°C;

[0011] The mass concentration of titanium in the catalyst for synthesizing high color value PBT resin is 4-6%;

[0012] The molar ratio of the phosphorus compound B, diol C, metal salt compound D, aliphatic organic alcohol acid E, aliphatic organic polyether F, blue toner G and titanium compound A is 0.1-0.5:1-10:0.1-5:0.1-1:0.1-1:0.001-0.01:1.

[0013] Furthermore, the mass concentration of titanium in the catalyst for synthesizing high color value PBT resin is 5%;

[0014] The molar ratio of the phosphorus compound B, diol C, metal salt compound D, aliphatic organic alcohol acid E, aliphatic organic polyether F, blue toner G and titanium compound A is 0.25:4:1:0.3:1:0.01:1.

[0015] Furthermore, the structural formula of the titanium compound A is R1-R4 are independently selected from C1-C8 straight chain or branched alkyl groups;

[0016] The chemical formula of the phosphorus compound B is R is an alkyl group independently selected from C1-C5 or an aromatic group having an aromatic structure;

[0017] The diol C is at least one of ethylene glycol, propylene glycol, butanediol, pentanediol and hexanediol;

[0018] The metal compound D is at least one of magnesium acetate, calcium acetate, magnesium carbonate, calcium carbonate, magnesium hydroxide, calcium hydroxide, sodium acetate, potassium acetate, sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide;

[0019] The aliphatic organic compound E is at least one of glycerol, pentaerythritol, sorbitol, glycolic acid, lactic acid, citric acid, malic acid, tartaric acid, and oxalic acid;

[0020] The aliphatic organic polyether F is at least one of polyethylene glycol, polypropylene glycol and polybutylene glycol;

[0021] The blue toner G is at least one of ultramarine, anthraquinone blue, phthalocyanine blue and indigo.

[0022] The second object of the present invention is to provide a catalyst for synthesizing PBT resin, which is prepared by the above-mentioned preparation method.

[0023] The third object of the present invention is to provide a method for preparing a PBT resin. By using the above-mentioned catalyst for synthesizing a high color value PBT resin, the consumption of BDO raw materials can be reduced and the performance of the PBT resin can be improved.

[0024] In order to achieve the above purpose, the technical solution adopted is:

[0025] A method for preparing a PBT resin is as follows:

[0026] Mixing 1,4-butanediol, terephthalic acid and the above-mentioned catalyst for synthesizing the PBT resin, and performing an esterification reaction to obtain an esterified product;

[0027] The esterified product is subjected to a pre-polycondensation reaction to obtain a prepolymer;

[0028] subjecting the prepolymer to a final polycondensation reaction to obtain a final polymer;

[0029] The final polymer is cooled, pelletized and dried to obtain the high color value PBT resin.

[0030] Furthermore, the esterification reaction temperature is 220-230°C, the time is 2.5-3.5h, and the vacuum degree is 55-65kpa;

[0031] The pre-polycondensation reaction temperature is 230-240°C, the time is 1.5-2h, and the vacuum degree is 2-4kpa;

[0032] The temperature of the final polycondensation reaction is 235-245°C, the time is 2.5-3.5h, and the vacuum degree is 45-55pa;

[0033] The molar ratio of 1,4-butanediol to terephthalic acid is 1.3-1.7:1;

[0034] The dosage of the catalyst for synthesizing the PBT resin is: calculated as titanium element, 80-140 ppm of the total amount of the esterification product.

[0035] Furthermore, the vacuum degree of the esterification reaction is 60 kPa;

[0036] The vacuum degree of the pre-polycondensation reaction is 3 kpa;

[0037] The vacuum degree of the final polycondensation reaction is 50 Pa;

[0038] The molar ratio of 1,4-butanediol to terephthalic acid is 1.3-1.5:1;

[0039] The dosage of the catalyst for synthesizing the PBT resin is: calculated as titanium element, 100 ppm of the total amount of the esterified product.

[0040] Furthermore, the molar ratio of 1,4-butanediol to terephthalic acid is 1.4:1.

[0041] The fourth invention object of the present invention is to provide a PBT resin prepared by the above-mentioned preparation method, which has the advantages of good hue, low carboxyl content, strong hydrolysis resistance, stable elongation at break, high notched impact strength and excellent spinning quality.

[0042] Compared with the prior art, the present invention has the following beneficial effects:

[0043] The technical scheme of the present invention improves and adjusts the catalyst for synthesizing PBT resin, and is used to synthesize PBT resin. Under the condition of ensuring that the production process remains unchanged, PBT resin with good color, low carboxyl content, strong hydrolysis resistance, stable elongation at break, high notched impact strength and excellent spinning quality is prepared. DETAILED DESCRIPTION

[0044] In order to further explain the catalyst for synthesizing PBT resin and its preparation method, PBT resin and its preparation method of the present invention, and achieve the intended purpose of the invention, the following is a detailed description of the catalyst for synthesizing PBT resin and its preparation method, PBT resin and its preparation method according to the present invention, its specific implementation, structure, characteristics and efficacy in combination with the preferred embodiments. In the following description, different "one embodiment" or "embodiment" does not necessarily refer to the same embodiment. In addition, specific features, structures or characteristics in one or more embodiments may be combined in any suitable form.

[0045] The following will further introduce in detail a catalyst for synthesizing PBT resin and a preparation method, a PBT resin and a preparation method of the present invention in conjunction with specific embodiments:

[0046] The present invention takes the hue of PBT resin products as the research direction, analyzes and explores the factors affecting the hue of the PBT synthesis process item by item, and develops a catalyst for PBT resin synthesis under the condition of ensuring that the inherent production process remains unchanged, and develops a catalytic system for PBT resin production with good product hue, low carboxyl content, strong hydrolysis resistance, stable elongation at break, high notched impact strength, and excellent spinning quality. Specific embodiments are as follows:

[0047] Example 1.

[0048] The specific steps are as follows:

[0049] S10: Preparation of catalyst for PBT resin synthesis

[0050] Add diol C to a reactor equipped with a stirrer, a condenser and a thermometer, slowly drip titanium compound A into the reactor, react at 80-120°C for 3-4 hours, and a white precipitate is precipitated. The white precipitate is centrifuged, and the residue is washed with distilled water for 3 times and vacuum dried to obtain a white powdery substance.

[0051] The dried white powdery substance is placed in a reactor equipped with an agitator, a condenser and a thermometer, and 1,4-butanediol, a phosphorus compound B, a metal compound D, an aliphatic organic compound E, an aliphatic organic polyether F and a blue colorant G are added. The reaction is carried out at a reaction temperature of 120-140°C for 3.5-4.5 hours to obtain a nearly colorless homogeneous liquid, which is diluted with 1,4-butanediol to a mass concentration of titanium element of 4-6%, which is a catalyst for the synthesis of PBT resin.

[0052] The molar ratio of phosphorus compound B, diol C, metal salt compound D, aliphatic organic alcohol acid E, aliphatic organic polyether F, blue toner G and titanium compound A is 0.1-0.5: 1-10: 0.1-5: 0.1-1: 0.1-1: 0.001-0.01: 1. The addition ratio of each component higher than the above relevant ratio has a certain inhibitory effect on the reaction, resulting in a longer reaction time and causing product degradation; the addition ratio lower than the above ratio has a lower positive effect on the reaction.

[0053] The structural formula of titanium compound A is R1-R4 are independently selected from C1-C8 straight chain or branched alkyl groups;

[0054] The chemical formula of phosphorus compound B is R is an alkyl group independently selected from C1-C5 or an aromatic group having an aromatic structure;

[0055] The diol C is at least one of ethylene glycol, propylene glycol, butanediol, pentanediol and hexanediol;

[0056] The metal compound D is at least one of magnesium acetate, calcium acetate, magnesium carbonate, calcium carbonate, magnesium hydroxide, calcium hydroxide, sodium acetate, potassium acetate, sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide;

[0057] The aliphatic organic compound E is at least one of glycerol, pentaerythritol, sorbitol, glycolic acid, lactic acid, citric acid, malic acid, tartaric acid, and oxalic acid;

[0058] The aliphatic organic polyether F is at least one of polyethylene glycol, polypropylene glycol and polybutylene glycol;

[0059] The blue toner G is at least one of ultramarine, anthraquinone blue, phthalocyanine blue, and indigo.

[0060] S20: Preparation of PBT resin

[0061] (1) Terephthalic acid, 1,4-butanediol, and the catalyst for PBT resin synthesis prepared in step S10 (based on the amount of polyester generated (i.e., the amount of the target product ester Es), the mass concentration of titanium atoms is 80-140 ppm) are mixed into a slurry, and added into an esterification kettle to carry out an esterification reaction. The esterification reaction temperature is 220-230° C., the reaction vacuum is 55-65 kPa, the esterification time is 2.5-3.5 h, and the water, tetrahydrofuran and the remaining 1,4-butanediol generated by the reaction are discharged through a rectification device to obtain an ester Es.

[0062] Preferably, the molar ratio of 1,4-butanediol to terephthalic acid is 1.3-1.7:1.

[0063] Further preferably, the molar ratio of 1,4-butanediol to terephthalic acid is 1.3-1.5:1;

[0064] The dosage of the catalyst for synthesizing the PBT resin is: calculated as titanium element, 100 ppm of the total amount of the esterified product.

[0065] Still more preferably, the molar ratio of 1,4-butanediol to terephthalic acid is 1.4:1.

[0066] (2) After the esterification is completed, the esterified product Es is discharged into the polymerization reactor, and the reaction temperature is gradually controlled to rise to 230-240°C, and the reaction vacuum is slowly reduced from 55-65kpa to 2-4kpa for pre-condensation reaction. The pre-condensation time is 1.5-2h to obtain a prepolymer PP.

[0067] Then the reaction temperature is controlled to be 235-245°C, and the reaction vacuum is slowly reduced from 2-4 kPa to 45-55 Pa for final polycondensation reaction, and the final polycondensation time is 2.5-3.5 h to obtain the final polymer EP.

[0068] (3) After the reaction is completed, the final polymer EP is continuously extruded in strips from the bottom of the polymerization reactor, cooled, pelletized and dried to obtain PBT resin, i.e. polyester.

[0069] Example 2.

[0070] The specific steps are as follows:

[0071] S10: Preparation of Catalyst A

[0072] (1) After adding 24.8 g (0.4 mol) of ethylene glycol to a reactor equipped with a stirrer, a condenser and a thermometer, 34 g (0.1 mol) of tetrabutyl titanate was slowly added dropwise to the reactor, and reacted at 100° C. for 3 h to precipitate a white precipitate. The precipitate was centrifuged, washed with distilled water three times, and then vacuum dried at 100° C. to obtain a white powdery substance.

[0073] (2) The dried white powdery substance was placed in a reactor equipped with a stirrer, a condenser and a thermometer, 500 g of 1,4-butanediol and 8 g (0.025 mol) of triphenyl phosphate were added, and the mixture was reacted at 130° C. for 4 h to obtain a nearly colorless homogeneous liquid.

[0074] (3) The nearly colorless homogeneous liquid was diluted with 1,4-butanediol to a mass concentration of titanium element of 5%, thereby obtaining a catalyst for PBT resin synthesis, which is catalyst A.

[0075] S20: Preparation of PBT resin

[0076] (1) 3 kg of terephthalic acid, 2.65 kg of 1,4-butanediol (the molar ratio of 1,4-butanediol to terephthalic acid is 1.6:1) and catalyst A (based on the amount of polyester generated (i.e., the amount of the target product ester Es), the mass concentration of titanium atoms is 100 ppm) are mixed to form a slurry, which is added to an esterification kettle to carry out an esterification reaction. The esterification reaction temperature is 225° C., the reaction vacuum is 60 kPa, the esterification time is 3 hours, and the water, tetrahydrofuran and the remaining 1,4-butanediol generated by the reaction are discharged through a rectification device to obtain an esterified product Es.

[0077] (2) After the esterification is completed, the esterified product Es is discharged into the polymerization reactor, and the reaction temperature is gradually controlled to rise to 235°C. The reaction vacuum is slowly reduced from 60 kPa to 3 kPa for pre-condensation reaction. The pre-condensation time is 1.5 hours to obtain a prepolymer PP.

[0078] Then the reaction temperature was controlled at 240°C, and the reaction vacuum was slowly reduced from 3 kPa to 50 Pa for a final polycondensation reaction. The final polycondensation time was 3 h to obtain the final polymer EP.

[0079] (3) After the reaction is completed, the final polymer EP is continuously extruded in strips from the bottom of the polymerization reactor, cooled, pelletized and dried to obtain PBT resin, i.e. polyester.

[0080] Example 3.

[0081] The specific steps are as follows:

[0082] S10: Preparation of Catalyst B

[0083] (1) 24.8 g (0.4 mol) of ethylene glycol was added to a reactor equipped with a stirrer, a condenser and a thermometer, and 34 g (0.1 mol) of tetrabutyl titanate was slowly dripped into the reactor. The mixture was reacted at 100° C. for 3 h to precipitate a white precipitate. The precipitate was centrifuged, and the residue was washed with distilled water for 3 times and then vacuum dried at 100° C. to obtain a white powdery substance.

[0084] (2) The dried white powdery substance was placed in a reactor equipped with a stirrer, a condenser and a thermometer, 500 g of 1,4-butanediol, 8 g (0.025 mol) of triphenyl phosphate and 10.5 g (0.05 mol) of citric acid monohydrate were added, and the mixture was reacted at 130° C. for 4 h to obtain a nearly colorless homogeneous liquid.

[0085] (3) The nearly colorless homogeneous liquid was diluted with 1,4-butanediol to a mass concentration of titanium element of 5%, thereby obtaining a catalyst for PBT resin synthesis, which is catalyst B.

[0086] S20: Preparation of PBT resin

[0087] The same method as in Example 2 was used to prepare PBT resin.

[0088] Example 4.

[0089] The specific steps are as follows:

[0090] S10: Preparation of Catalyst C

[0091] (1) 24.8 g (0.4 mol) of ethylene glycol was added to a reactor equipped with a stirrer, a condenser and a thermometer, and 34 g (0.1 mol) of tetrabutyl titanate was slowly dripped into the reactor. The mixture was reacted at 100° C. for 3 h to precipitate a white precipitate. The precipitate was centrifuged, and the residue was washed with distilled water for 3 times and then vacuum dried at 100° C. to obtain a white powdery substance.

[0092] (2) The dried white powdery substance was placed in a reactor equipped with a stirrer, a condenser and a thermometer, and 500 g of 1,4-butanediol, 8 g (0.025 mol) of triphenyl phosphate, 6.3 g (0.03 mol) of citric acid monohydrate and 164 g (0.2 mol) of sodium acetate were added. The mixture was reacted at 130° C. for 4 h to obtain a nearly colorless homogeneous liquid.

[0093] (3) The nearly colorless homogeneous liquid was diluted with 1,4-butanediol to a titanium concentration of 5% to obtain a catalyst for PBT resin synthesis, which is catalyst C.

[0094] S20: Preparation of PBT resin

[0095] The same method as in Example 2 was used to prepare PBT resin.

[0096] Example 5.

[0097] The specific steps are as follows:

[0098] S10: Preparation of Catalyst D

[0099] (1) 24.8 g (0.4 mol) of ethylene glycol was added to a reactor equipped with a stirrer, a condenser and a thermometer, and 34 g (0.1 mol) of tetrabutyl titanate was slowly dripped into the reactor. The mixture was reacted at 100° C. for 3 h to precipitate a white precipitate. The precipitate was centrifuged, and the residue was washed with distilled water for 3 times and then vacuum dried at 100° C. to obtain a white powdery substance.

[0100] (2) The dried white powdery substance was placed in a reactor equipped with a stirrer, a condenser and a thermometer, and 500 g of 1,4-butanediol, 8 g (0.025 mol) of triphenyl phosphate, 6.3 g (0.03 mol) of citric acid monohydrate, 82 g (0.1 mol) of sodium acetate and 200 g (0.1 mol) of polyethylene glycol were added, and the mixture was reacted at 130° C. for 4 h to obtain a nearly colorless homogeneous liquid.

[0101] (3) The nearly colorless homogeneous liquid was diluted with 1,4-butanediol to a mass concentration of titanium element of 5%, thereby obtaining a catalyst for PBT resin synthesis, which is catalyst D.

[0102] S20: Preparation of PBT resin

[0103] The same method as in Example 2 was used to prepare PBT resin.

[0104] Example 6.

[0105] The specific steps are as follows:

[0106] S10: Preparation of Catalyst E

[0107] (1) 24.8 g (0.4 mol) of ethylene glycol was added to a reactor equipped with a stirrer, a condenser and a thermometer, and 34 g (0.1 mol) of tetrabutyl titanate was slowly dripped into the reactor. The mixture was reacted at 100° C. for 3 h to precipitate a white precipitate. The precipitate was centrifuged, and the residue was washed with distilled water for 3 times and then vacuum dried at 100° C. to obtain a white powdery substance.

[0108] (2) The dried white powdery substance was placed in a reactor equipped with a stirrer, a condenser and a thermometer, and 500 g of 1,4-butanediol, 8 g (0.025 mol) of triphenyl phosphate, 6.3 g (0.03 mol) of citric acid monohydrate, 82 g (0.1 mol) of sodium acetate, 200 g (0.1 mol) of polyethylene glycol and anthraquinone blue (0.001 mol) were added, and the mixture was reacted at 130° C. for 4 h to obtain a nearly colorless homogeneous liquid.

[0109] (3) The nearly colorless homogeneous liquid was diluted with 1,4-butanediol to a mass concentration of titanium element of 5%, thereby obtaining a catalyst for PBT resin synthesis, which is catalyst E.

[0110] S20: Preparation of PBT resin

[0111] The same method as in Example 2 was used to prepare PBT resin.

[0112] Comparative Example 1.

[0113] 3 kg of terephthalic acid, 2.65 kg of 1,4-butanediol and catalyst tetrabutyl titanate (based on the amount of polyester generated (i.e. the amount of the target product ester Es), the mass concentration of titanium atoms is 100 ppm) are mixed into a slurry, added into an esterification kettle, and an esterification reaction is carried out at a temperature of 225° C., a reaction vacuum of 60 kPa, and an esterification time of 3 h. The water, tetrahydrofuran and remaining 1,4-butanediol generated by the reaction are discharged through a distillation device to obtain an ester Es.

[0114] After the esterification is completed, the esterified product Es is discharged into the polymerization reactor, the reaction temperature is gradually controlled to rise to 235°C, and the reaction vacuum is slowly reduced from 60kpa to 3kpa for pre-condensation reaction. The pre-condensation time is 1.5h to obtain the prepolymer PP.

[0115] Then the reaction temperature was controlled to rise to 240°C, and the reaction vacuum was slowly reduced from 3 kPa to 50 Pa to carry out the final polycondensation reaction. The final polycondensation time was about 3 hours to obtain the final polymer EP.

[0116] After the reaction is completed, the final polymer EP is continuously extruded in strips from the bottom of the polymerization reactor, cooled, pelletized and dried to obtain PBT resin.

[0117] Example 7.

[0118] The PBT resin products prepared in Examples 2-6 and Comparative Example 1 were tested for relevant properties such as viscosity, hue, melt index, melting point, carboxyl group, and mechanical properties.

[0119] The intrinsic viscosity, hue melt index, melting point, carboxyl group, mechanical properties, etc. of PBT resin are tested by the following methods:

[0120] (1) Intrinsic viscosity: Phenol-tetrachloroethane mixture was used as solvent and measured with an Ubbelohde viscometer at 25°C.

[0121] (2) Hue: After the pellet sample was treated at 135°C for 1 hour, its Hunter L value (brightness), a value (red-green hue) and b value (yellow-blue hue) were measured using a BYK Gardner color-view automatic colorimeter. The higher the L value, the greater the brightness; the higher the b value, the yellower the polyester chips. For the present invention, it is desirable to pursue a high L value and a low b value.

[0122] (3) Melt index: measured at 250°C and 2.16 kg using an Instron CEAST MF20 melt flow rate tester.

[0123] (4) Melting point: The melting point was measured using a Shimadzu DSC-60Plus differential scanning calorimeter at a heating rate of 20°C / min.

[0124] (5) Carboxyl: The mass ratio of o-cresol to chloroform was 7:3 as the mixed solvent and potassium hydroxide-benzyl alcohol was used as the titrant for determination by volumetric titration.

[0125] (6) Mechanical properties: The specimens were injection molded into Type IA strips by an injection molding machine. The tensile strength and elongation at break were tested at a tensile speed of 50 mm / min. The cantilever beam notch impact test was performed by cutting a right-angle notch on the strips.

[0126] The test results are shown in Table 1.

[0127] Table 1

[0128]

[0129] Combined with Table 1, it can be seen that the PBT resin prepared by the present invention has the best performance, reduces the carboxyl group of the product, and improves the thermal stability, hydrolysis resistance and mechanical properties of the product. The PBT resin synthesized by this method has product hue, carboxyl group and mechanical properties that are significantly better than the PBT foreign trade product indicators, which provides more options for PBT resin products to expand the foreign trade market and serve the domestic market.

[0130] Example 8.

[0131] The specific steps are as follows:

[0132] S10: Preparation of Catalyst E

[0133] Catalyst E was prepared in the same manner as in Example 6.

[0134] S20: Preparation of PBT resin

[0135] Preparation of PBT resin

[0136] (1) 3 kg of terephthalic acid, 2.15 kg of 1,4-butanediol (the molar ratio of 1,4-butanediol to terephthalic acid is 1.3:1) and catalyst E (based on the amount of polyester generated (i.e., the amount of the target product ester Es), the mass concentration of titanium atoms is 100 ppm) are mixed into a slurry, and added into an esterification kettle to carry out an esterification reaction. The esterification reaction temperature is 225° C., the reaction vacuum is 60 kPa, the esterification time is 3 hours, and the water, tetrahydrofuran and the remaining 1,4-butanediol generated by the reaction are discharged through a rectification device to obtain an ester Es.

[0137] (2) After the esterification is completed, the esterified product Es is discharged into the polymerization reactor, and the reaction temperature is gradually controlled to rise to 235°C. The reaction vacuum is slowly reduced from 60 kPa to 3 kPa for pre-condensation reaction. The pre-condensation time is 1.5 hours to obtain a prepolymer PP.

[0138] Then the reaction temperature was controlled at 240°C, and the reaction vacuum was slowly reduced from 3 kPa to 50 Pa for a final polycondensation reaction. The final polycondensation time was 3 h to obtain the final polymer EP.

[0139] (3) After the reaction is completed, the final polymer EP is continuously extruded in strips from the bottom of the polymerization reactor, cooled, pelletized and dried to obtain PBT resin, i.e. polyester.

[0140] Example 9.

[0141] The specific steps are as follows:

[0142] S10: Preparation of Catalyst E

[0143] Catalyst E was prepared in the same manner as in Example 6.

[0144] S20: Preparation of PBT resin

[0145] Preparation of PBT resin

[0146] (1) 3 kg of terephthalic acid, 2.32 kg of 1,4-butanediol (the molar ratio of 1,4-butanediol to terephthalic acid is 1.4:1) and catalyst E (based on the amount of polyester generated (i.e., the amount of the target product ester Es), the mass concentration of titanium atoms is 100 ppm) are mixed into a slurry, and added into an esterification kettle to carry out an esterification reaction. The esterification reaction temperature is 225° C., the reaction vacuum is 60 kPa, the esterification time is 3 hours, and the water, tetrahydrofuran and the remaining 1,4-butanediol generated by the reaction are discharged through a rectification device to obtain an ester Es.

[0147] (2) After the esterification is completed, the esterified product Es is discharged into the polymerization reactor, and the reaction temperature is gradually controlled to rise to 235°C. The reaction vacuum is slowly reduced from 60 kPa to 3 kPa for pre-condensation reaction. The pre-condensation time is 1.5 hours to obtain a prepolymer PP.

[0148] Then the reaction temperature was controlled at 240°C, and the reaction vacuum was slowly reduced from 3 kPa to 50 Pa for a final polycondensation reaction. The final polycondensation time was 3 h to obtain the final polymer EP.

[0149] (3) After the reaction is completed, the final polymer EP is continuously extruded in strips from the bottom of the polymerization reactor, cooled, pelletized and dried to obtain PBT resin, i.e. polyester.

[0150] Example 10.

[0151] The specific steps are as follows:

[0152] S10: Preparation of Catalyst E

[0153] Catalyst E was prepared in the same manner as in Example 6.

[0154] S20: Preparation of PBT resin

[0155] Preparation of PBT resin

[0156] (1) 3 kg of terephthalic acid, 2.485 kg of 1,4-butanediol (the molar ratio of 1,4-butanediol to terephthalic acid is 1.5:1) and catalyst E (based on the amount of polyester generated (i.e., the amount of the target product ester Es), the mass concentration of titanium atoms is 100 ppm) are mixed to form a slurry, which is added to an esterification kettle to carry out an esterification reaction. The esterification reaction temperature is 225° C., the reaction vacuum is 60 kPa, the esterification time is 3 hours, and the water, tetrahydrofuran and the remaining 1,4-butanediol generated by the reaction are discharged through a rectification device to obtain an ester Es.

[0157] (2) After the esterification is completed, the esterified product Es is discharged into the polymerization reactor, and the reaction temperature is gradually controlled to rise to 235°C. The reaction vacuum is slowly reduced from 60 kPa to 3 kPa for pre-condensation reaction. The pre-condensation time is 1.5 hours to obtain a prepolymer PP.

[0158] Then the reaction temperature was controlled at 240°C, and the reaction vacuum was slowly reduced from 3 kPa to 50 Pa for a final polycondensation reaction. The final polycondensation time was 3 h to obtain the final polymer EP.

[0159] (3) After the reaction is completed, the final polymer EP is continuously extruded in strips from the bottom of the polymerization reactor, cooled, pelletized and dried to obtain PBT resin, i.e. polyester.

[0160] Embodiment 11

[0161] The specific steps are as follows:

[0162] S10: Preparation of Catalyst E

[0163] Catalyst E was prepared in the same manner as in Example 6.

[0164] S20: Preparation of PBT resin

[0165] Preparation of PBT resin

[0166] (1) 3 kg of terephthalic acid, 2.82 kg of 1,4-butanediol (the molar ratio of 1,4-butanediol to terephthalic acid is 1.7:1) and catalyst E (based on the amount of polyester generated (i.e., the amount of the target product ester Es), the mass concentration of titanium atoms is 100 ppm) are mixed into a slurry, and added into an esterification kettle to carry out an esterification reaction. The esterification reaction temperature is 225° C., the reaction vacuum is 60 kPa, the esterification time is 3 hours, and the water, tetrahydrofuran and the remaining 1,4-butanediol generated by the reaction are discharged through a rectification device to obtain an ester Es.

[0167] (2) After the esterification is completed, the esterified product Es is discharged into the polymerization reactor, and the reaction temperature is gradually controlled to rise to 235°C. The reaction vacuum is slowly reduced from 60 kPa to 3 kPa for pre-condensation reaction. The pre-condensation time is 1.5 hours to obtain a prepolymer PP.

[0168] Then the reaction temperature was controlled at 240°C, and the reaction vacuum was slowly reduced from 3 kPa to 50 Pa for a final polycondensation reaction. The final polycondensation time was 3 h to obtain the final polymer EP.

[0169] (3) After the reaction is completed, the final polymer EP is continuously extruded in strips from the bottom of the polymerization reactor, cooled, pelletized and dried to obtain PBT resin, i.e. polyester.

[0170] The PBT resins prepared in Examples 6 and 8-11 were tested for relevant properties such as viscosity, hue, melt index, melting point, carboxyl group, and mechanical properties using the method of Example 7. The difference between Examples 6 and 8-11 is that the molar ratio of terephthalic acid to 1,4-butanediol and the molar ratio of 1,4-butanediol to terephthalic acid are 1.3:1, 1.4:1, 1.5:1, 1.6:1, and 1.7:1, respectively.

[0171] The test results are shown in Table 2.

[0172] Table 2

[0173]

[0174] It can be seen from Table 2-3 that the improved catalyst of the present invention has a high yield and good performance in preparing PBT resin when the molar ratio of 1,4-butanediol to terephthalic acid is 1.3-1.7:1.

[0175] From an economic perspective, when the molar ratio of 1,4-butanediol to terephthalic acid is 1.3-1.5:1, the consumption of the raw material BDO is less while ensuring product quality, which can reduce costs. Among them, the most preferred molar ratio of 1,4-butanediol to terephthalic acid is 1.4:1.

[0176] Example 12.

[0177] S10: Preparation of Catalyst F

[0178] (1) 24.8 g (0.4 mol) of ethylene glycol was added to a reactor equipped with a stirrer, a condenser and a thermometer, and 34 g (0.1 mol) of tetrabutyl titanate was slowly dripped into the reactor. The mixture was reacted at 100° C. for 3 h to precipitate a white precipitate. The precipitate was centrifuged, and the residue was washed with distilled water for 3 times and then vacuum dried at 100° C. to obtain a white powdery substance.

[0179] (2) The dried white powdery substance was placed in a reactor equipped with a stirrer, a condenser and a thermometer, and 500 g of 1,4-butanediol, 2.4 g (0.025 mol) of trimethyl phosphate, 6.3 g (0.03 mol) of citric acid monohydrate, 82 g (0.1 mol) of sodium acetate, 200 g (0.1 mol) of polyethylene glycol and anthraquinone blue (0.001 mol) were added, and the mixture was reacted at 130° C. for 4 h to obtain a nearly colorless homogeneous liquid.

[0180] (3) The nearly colorless homogeneous liquid was diluted with 1,4-butanediol to a mass concentration of titanium element of 5%, thereby obtaining a catalyst for PBT resin synthesis, which is catalyst F.

[0181] S20: Preparation of PBT resin

[0182] The same method as in Example 2 was used to prepare PBT resin.

[0183] Example 13.

[0184] S10: Preparation of Catalyst G

[0185] (1) 24.8 g (0.4 mol) of ethylene glycol was added to a reactor equipped with a stirrer, a condenser and a thermometer, and 34 g (0.1 mol) of tetrabutyl titanate was slowly dripped into the reactor. The mixture was reacted at 100° C. for 3 h to precipitate a white precipitate. The precipitate was centrifuged, and the residue was washed with distilled water for 3 times and then vacuum dried at 100° C. to obtain a white powdery substance.

[0186] (2) The dried white powdery substance was placed in a reactor equipped with a stirrer, a condenser and a thermometer, and 500 g of 1,4-butanediol, 4.75 g (0.025 mol) of triethyl phosphate, 6.3 g (0.03 mol) of citric acid monohydrate, 82 g (0.1 mol) of sodium acetate, 200 g (0.1 mol) of polyethylene glycol and anthraquinone blue (0.001 mol) were added, and the mixture was reacted at 130° C. for 4 h to obtain a nearly colorless homogeneous liquid.

[0187] (3) The nearly colorless homogeneous liquid was diluted with 1,4-butanediol to a mass concentration of titanium element of 5%, thereby obtaining a catalyst for PBT resin synthesis, which is catalyst G.

[0188] S20: Preparation of PBT resin

[0189] The same method as in Example 2 was used to prepare PBT resin.

[0190] The PBT resin prepared in Examples 12-13 was tested for related properties such as viscosity, hue, melt index, melting point, carboxyl group, and mechanical properties using the method of Example 7.

[0191] The test results are shown in Table 3.

[0192] Table 3

[0193]

[0194] It can be seen from the data in Table 3 that different phosphates have little effect on the product indicators of the reaction process. In view of the higher stability of triphenyl phosphate, triphenyl phosphate is preferred for the reaction.

[0195] Example 14.

[0196] The specific steps are as follows:

[0197] S10: Preparation of catalyst for PBT resin synthesis

[0198] Propylene glycol (0.1 mol) was added to a reactor equipped with a stirrer, a condenser and a thermometer, and tetraisopropyl titanate (0.1 mol) was slowly dripped into the reactor, and the reaction was carried out at 80°C for 4 hours to precipitate a white precipitate. The white precipitate was centrifuged, and the residue was washed with distilled water 3 times and vacuum dried to obtain a white powdery substance.

[0199] The dried white powdery substance is placed in a reactor equipped with an agitator, a condenser and a thermometer, and 1,4-butanediol, diphenyl phosphate (0.01 mol), sodium hydroxide (0.01 mol), malic acid (0.01 mol), polypropylene glycol (0.01 mol), and phthalocyanine blue (0.0001 mol) are added. The reaction is carried out at a reaction temperature of 120°C for 4.5 hours to obtain a nearly colorless homogeneous liquid, which is diluted with 1,4-butanediol to a mass concentration of titanium element of 4%, which is a catalyst for the synthesis of PBT resin.

[0200] S20: Preparation of PBT resin

[0201] (1) 3 kg of terephthalic acid, 2.65 kg of 1,4-butanediol, and the catalyst for PBT resin synthesis prepared in step S10 (based on the amount of polyester generated (i.e., the amount of the target product ester Es), the mass concentration of titanium atoms is 80 ppm) are mixed into a slurry, and added into an esterification kettle to carry out an esterification reaction. The esterification reaction temperature is 230° C., the reaction vacuum is 65 kPa, the esterification time is 3.5 h, and the water, tetrahydrofuran and the remaining 1,4-butanediol generated by the reaction are discharged through a rectification device to obtain an esterified product Es.

[0202] (2) After the esterification is completed, the esterified product Es is discharged into the polymerization reactor, the reaction temperature is gradually controlled to rise to 230°C, and the reaction vacuum is slowly reduced from 65 kPa to 4 kPa for pre-condensation reaction. The pre-condensation time is 2 hours to obtain a prepolymer PP.

[0203] Then the reaction temperature was controlled at 235°C, and the reaction vacuum was slowly reduced from 4 kPa to 55 Pa for a final polycondensation reaction. The final polycondensation time was 3.5 h to obtain the final polymer EP.

[0204] (3) After the reaction is completed, the final polymer EP is continuously extruded in strips from the bottom of the polymerization reactor, cooled, pelletized and dried to obtain PBT resin, i.e. polyester.

[0205] Example 15.

[0206] The specific steps are as follows:

[0207] S10: Preparation of catalyst for PBT resin synthesis

[0208] Butanediol (1 mol) was added to a reactor equipped with a stirrer, a condenser and a thermometer, and tetraethyl titanate (0.1 mol) was slowly dripped into the reactor, and the reaction was carried out at 120°C for 3 hours to precipitate a white precipitate. The white precipitate was centrifuged, and the residue was washed with distilled water 3 times and vacuum dried to obtain a white powdery substance.

[0209] The dried white powdery substance is placed in a reactor equipped with an agitator, a condenser and a thermometer, and 1,4-butanediol, monophenyl phosphate (0.05 mol), magnesium carbonate (0.5 mol), pentaerythritol (0.05 mol), polybutylene glycol (0.05 mol), and indigo (0.0005 mol) are added. The mixture is reacted at a reaction temperature of 140°C for 3.5 hours to obtain a nearly colorless homogeneous liquid, which is diluted with 1,4-butanediol to a mass concentration of 6% of titanium element, which is a catalyst for the synthesis of PBT resin.

[0210] S20: Preparation of PBT resin

[0211] (1) 3 kg of terephthalic acid, 2.65 kg of 1,4-butanediol, and the catalyst for PBT resin synthesis prepared in step S10 (based on the amount of polyester generated (i.e., the amount of the target product ester Es), the mass concentration of titanium atoms is 140 ppm) are mixed into a slurry, and added into an esterification kettle to carry out an esterification reaction. The esterification reaction temperature is 220° C., the reaction vacuum is 55 kPa, the esterification time is 2.5 h, and the water, tetrahydrofuran and the remaining 1,4-butanediol generated by the reaction are discharged through a rectification device to obtain an esterified product Es.

[0212] (2) After the esterification is completed, the esterified product Es is discharged into the polymerization reactor, and the reaction temperature is gradually controlled to rise to 240°C. The reaction vacuum is slowly reduced from 55 kPa to 2 kPa for pre-condensation reaction. The pre-condensation time is 1.5 h to obtain a prepolymer PP.

[0213] Then the reaction temperature was controlled at 245°C, and the reaction vacuum was slowly reduced from 2 kPa to 45 Pa for a final polycondensation reaction. The final polycondensation time was 2.5 h to obtain the final polymer EP.

[0214] (3) After the reaction is completed, the final polymer EP is continuously extruded in strips from the bottom of the polymerization reactor, cooled, pelletized and dried to obtain PBT resin, i.e. polyester.

[0215] Example 16.

[0216] The specific steps are as follows:

[0217] S10: Preparation of catalyst for PBT resin synthesis

[0218] Pentanediol (0.5 mol) was added to a reactor equipped with a stirrer, a condenser and a thermometer, and tetraethyl titanate (0.1 mol) was slowly dripped into the reactor, and the reaction was carried out at 110°C for 3.5 hours to precipitate a white precipitate. The white precipitate was centrifuged, and the residue was washed with distilled water for 3 times and vacuum dried to obtain a white powdery substance.

[0219] The dried white powdery substance is placed in a reactor equipped with an agitator, a condenser and a thermometer, and 1,4-butanediol, triphenyl phosphate (0.03 mol), calcium acetate (0.2 mol), sorbitol (0.05 mol), polybutylene glycol (0.05 mol), and ultramarine (0.004 mol) are added. The mixture is reacted at a reaction temperature of 125°C for 4 hours to obtain a nearly colorless homogeneous liquid, which is diluted with 1,4-butanediol to a mass concentration of 5% of titanium element, which is a catalyst for the synthesis of PBT resin.

[0220] S20: Preparation of PBT resin

[0221] (1) 3 kg of terephthalic acid, 2.65 kg of 1,4-butanediol, and the catalyst for PBT resin synthesis prepared in step S10 (based on the amount of polyester generated (i.e., the amount of the target product ester Es), the mass concentration of titanium atoms is 120 ppm) are mixed into a slurry, and added into an esterification kettle to carry out an esterification reaction. The esterification reaction temperature is 225° C., the reaction vacuum is 60 kPa, the esterification time is 3 h, and the water, tetrahydrofuran and the remaining 1,4-butanediol generated by the reaction are discharged through a rectification device to obtain an ester Es.

[0222] (2) After the esterification is completed, the esterified product Es is discharged into the polymerization reactor, and the reaction temperature is gradually controlled to rise to 235°C. The reaction vacuum is slowly reduced from 60 kPa to 3 kPa for pre-condensation reaction. The pre-condensation time is 2 hours to obtain a prepolymer PP.

[0223] Then the reaction temperature was controlled at 240°C, and the reaction vacuum was slowly reduced from 3 kPa to 50 Pa for a final polycondensation reaction. The final polycondensation time was 3 h to obtain the final polymer EP.

[0224] (3) After the reaction is completed, the final polymer EP is continuously extruded in strips from the bottom of the polymerization reactor, cooled, pelletized and dried to obtain PBT resin, i.e. polyester.

[0225] Example 16.

[0226] The operating steps of Example 16 are the same as those of Example 6, except for the selection of metal compound D, as shown in Table 4.

[0227] Table 4

[0228]

[0229] Example 17.

[0230] The operation steps of Example 17 are the same as those of Example 6, except for the selection of the aliphatic organic compound E, as shown in Table 5.

[0231] Table 5

[0232]

[0233] The above is only a preferred embodiment of the embodiment of the present invention, and does not impose any form of limitation on the embodiment of the present invention. Any simple modification, equivalent changes and modifications made to the above embodiment based on the technical essence of the embodiment of the present invention are still within the scope of the technical solution of the embodiment of the present invention.

Claims

1. A method for preparing a catalyst for PBT resin synthesis, characterized in that: The preparation method is: Transesterify the titanium compound A with the diol C to obtain product 1; The product 1 is added to 1,4-butanediol, and then a phosphorus compound B, a metal compound D, an aliphatic organic compound E, an aliphatic organic polyether F, and a blue colorant G are added. After reacting at 120-140°C for 3.5-4.5 hours, the product 1 is diluted with 1,4-butanediol to obtain a homogeneous liquid titanium-based polyester catalyst, i.e., the catalyst for PBT resin synthesis.

2. The preparation method according to claim 1, characterized in that: The temperature of the transesterification reaction is 80-120°C; The mass concentration of titanium in the catalyst for synthesizing high color value PBT resin is 4-6%; The molar ratio of the phosphorus compound B, diol C, metal salt compound D, aliphatic organic alcohol acid E, aliphatic organic polyether F, blue toner G and titanium compound A is 0.1-0.5:1-10:0.1-5:0.1-1:0.1-1:0.001-0.01:

1.

3. The preparation method according to claim 2, characterized in that: The mass concentration of titanium in the catalyst for synthesizing high color value PBT resin is 5%; The molar ratio of the phosphorus compound B, diol C, metal salt compound D, aliphatic organic alcohol acid E, aliphatic organic polyether F, blue toner G and titanium compound A is 0.25:4:1:0.3: 1：0.01：1。 4. The preparation method according to claim 1, characterized in that: The structural formula of the titanium compound A is R1-R4 are independently selected from C1-C8 straight chain or branched alkyl groups; The chemical formula of the phosphorus compound B is R is an alkyl group independently selected from C1-C5 or an aromatic group having an aromatic structure; The diol C is at least one of ethylene glycol, propylene glycol, butanediol, pentanediol and hexanediol; The metal compound D is at least one of magnesium acetate, calcium acetate, magnesium carbonate, calcium carbonate, magnesium hydroxide, calcium hydroxide, sodium acetate, potassium acetate, sodium carbonate, potassium carbonate, sodium hydroxide, and potassium hydroxide; The aliphatic organic compound E is at least one of glycerol, pentaerythritol, sorbitol, glycolic acid, lactic acid, citric acid, malic acid, tartaric acid, and oxalic acid; The aliphatic organic polyether F is at least one of polyethylene glycol, polypropylene glycol and polybutylene glycol; The blue toner G is at least one of ultramarine, anthraquinone blue, phthalocyanine blue and indigo.

5. A catalyst for PBT resin synthesis, characterized in that: The preparation method is described in any one of claims 1 to 4.

6. A method for preparing a PBT resin, characterized in that: The preparation method is: Mixing 1,4-butanediol, terephthalic acid and the catalyst for synthesizing the PBT resin according to claim 5, and performing an esterification reaction to obtain an esterified product; The esterified product is subjected to a pre-polycondensation reaction to obtain a prepolymer; subjecting the prepolymer to a final polycondensation reaction to obtain a final polymer; The final polymer is cooled, pelletized and dried to obtain the high color value PBT resin.

7. The preparation method according to claim 6, characterized in that: The temperature of the esterification reaction is 220-230°C, the time is 2.5-3.5h, and the vacuum degree is 55-65kpa; The pre-polycondensation reaction temperature is 230-240°C, the time is 1.5-2h, and the vacuum degree is 2-4kpa; The temperature of the final polycondensation reaction is 235-245°C, the time is 2.5-3.5h, and the vacuum degree is 45-55pa; The molar ratio of 1,4-butanediol to terephthalic acid is 1.3-1.7:1; The dosage of the catalyst for synthesizing the PBT resin is: calculated as titanium element, 80-140 ppm of the total amount of the esterification product.

8. The preparation method according to claim 7, characterized in that: The vacuum degree of the esterification reaction is 60 kpa; The vacuum degree of the pre-polycondensation reaction is 3 kpa; The vacuum degree of the final polycondensation reaction is 50 Pa; The molar ratio of 1,4-butanediol to terephthalic acid is 1.3-1.5:1; The dosage of the catalyst for synthesizing the PBT resin is: calculated as titanium element, 100 ppm of the total amount of the esterified product.

9. The preparation method according to claim 8, characterized in that: The molar ratio of 1,4-butanediol to terephthalic acid is 1.4:

1.

10. A PBT resin, characterized in that: The method is prepared by any one of claims 6 to 9.

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