A polybutylene terephthalate resin particle and a method for producing the same

Abstract

This invention discloses a polybutylene terephthalate resin particle and its production method, comprising the following raw materials in parts by weight: 40-45 parts terephthalic acid, 45-50 parts 1,4-butanediol, 0.5-0.8 parts titanium catalyst, 2-4 parts flame retardant, 0.4-0.8 parts reinforcing agent, and 1-5 parts antioxidant. The production process includes the following steps: S1: synthesizing polyester, S2: drying and mixing, and S3: melt molding. The titanium catalyst used in the polymerization reaction is a titanium ammonium lactate chelate, and the relevant production method is set to improve the hydrolysis resistance and stability of the product.

Description

Technical Field

[0001] This invention relates to the technical field of polymer materials, specifically to a polybutylene terephthalate resin particle and its production method. Background Technology

[0002] Polybutylene terephthalate (PBT) is a thermoplastic polyester formed by the condensation polymerization of terephthalic acid (PTA) and butanediol (BDO). It possesses excellent mechanical, physical, and chemical properties, such as ease of processing, high-temperature resistance, chemical resistance, oil resistance, and good mechanical strength, and is widely used in the automotive, machinery, instrumentation, electronics, home appliances, textile, and consumer electronics industries. While PBT resin exhibits excellent hydrolysis resistance under dry heat conditions, it is highly susceptible to hydrolysis in many applications, such as underground optical cables, automotive parts, electrical appliances, and solar thin films, when exposed to significant amounts of moisture and high temperatures during humid aging.

[0003] Currently, the main catalysts used in industrial PBT production are alkoxy titanium, such as tetrabutyl titanate (TBT) and tetraisopropyl titanate (TPT). However, alkoxy titanium is prone to hydrolysis during polyester synthesis, producing titanium dioxide and titanium condensates, which precipitate and deactivate. This hydrolysis and precipitation not only remains in the PBT resin, leading to quality problems such as deterioration of its fog value and increased impurities, but also deposits inside equipment, causing production problems such as heat transfer issues and blockages. Furthermore, with the increasing demands for material performance in the electronics and electrical appliance industry, there are higher requirements for flame retardancy, viscosity characteristics, product quality uniformity, and tensile toughness. Summary of the Invention

[0004] To solve the above-mentioned technical problems, the present invention provides polybutylene terephthalate resin particles and a method for producing the same.

[0005] The technical solution of the present invention is: a polybutylene terephthalate resin particle, which is a particle of a polybutylene terephthalate resin composition, wherein the particle comprises, by weight parts: 40-45 parts of terephthalic acid, 45-50 parts of 1,4-butanediol, 0.5-0.8 parts of titanium catalyst, 2-4 parts of flame retardant, 0.4-0.8 parts of reinforcing agent, and 1-5 parts of antioxidant.

[0006] Furthermore, the titanium catalyst is a titanium ammonium lactate chelate, and the preparation steps of the titanium ammonium lactate chelate are as follows:

[0007] 1) Stir lactic acid and ammonia water at room temperature for 1-2 hours to obtain ammonium lactate solution; wherein the mass ratio of lactic acid to ammonia water is 2:1;

[0008] 2) Add titanate to an aluminum hydroxide solution with a pH of 9.0–9.3, and stir the reaction at 30–50°C for 1–3 hours, then cool to room temperature to obtain an alkaline solution; wherein the mass ratio of titanate to aluminum hydroxide in the aluminum hydroxide solution is 1:2–3.

[0009] 3) Add ammonium lactate solution dropwise to the alkaline solution at a rate of 5-10 drops / min, while continuously stirring and heating from room temperature to 70-90°C. Once the pH reaches 8.7-8.9, add ammonium lactate solution dropwise at a rate of 15-30 drops / min, stirring until all the water in the alkaline solution has evaporated. Then cool to room temperature to obtain the titanium catalyst. The mass ratio of ammonium lactate solution to alkaline solution is 1:1-2.

[0010] Explanation: Titanium chelates are compounds formed by the coordination bonding of titanate Ti(OR)4 with ligands containing lone pairs of electrons. The core of this process is the coordination bond. Compared to other ligands, using lactic acid as a ligand results in a more complete chelation reaction with less titanate precipitation, allowing the titanium chelates to exist stably in water. This also increases adhesion and improves surface hardness. Adjusting the pH of the chelation reaction process makes it more rational and controllable, enhancing the chelation effect. Placing titanate in an aluminum hydroxide solution prevents hydrolysis due to its weak alkalinity. The addition of aluminum provides catalytic activity, further enhancing catalyst activity. Furthermore, aluminum hydroxide's flame-retardant properties both aid in catalysis and flame retardancy.

[0011] Furthermore, the flame retardant is a silicone-based flame retardant, the reinforcing agent is a mixture of EPDM-g-MAH and POE-g-MAH at a mass ratio of 2 to 3:1, and the antioxidant is a mixed powder of antioxidant 1010 and antioxidant 168 at a mass ratio of 5 to 6:1.

[0012] Note: The use of silicone-based flame retardant oligomers can simultaneously achieve flame retardancy and dispersion, improve mechanical and electrical properties, and increase chemical resistance and impact strength; the use of a mixed powder of antioxidant 1010 and antioxidant 168 in the above ratio can further improve the stability of polyester, thereby better inhibiting PBT aging; the use of SEBS-g-MAH copolymer as a toughening agent can further improve the mechanical properties of PBT.

[0013] Furthermore, the intrinsic viscosity of the polybutylene terephthalate resin particles is 1.15–1.25 dl / g, and the average mass is 3 mg–9 mg / particle.

[0014] A method for producing polybutylene terephthalate resin particles includes the following steps:

[0015] S1: Synthetic polyester. Terephthalic acid and 1,4-butanediol are placed in a reactor. The reactor temperature is gradually increased from room temperature to 205℃~220℃. Under normal pressure, terephthalic acid and 1,4-butanediol undergo esterification reaction. Titanium catalyst is intermittently added to the reactor. After stirring for 100~180min, the reactor pressure is reduced to 70Pa~90Pa, and the temperature is adjusted to 250℃~255℃. Polycondensation is carried out for 100~160min to synthesize polybutylene terephthalate resin masterbatch.

[0016] S2: Drying and Mixing: After cooling the polybutylene terephthalate resin masterbatch to room temperature, it is pulverized into polybutylene terephthalate resin fragments. The polybutylene terephthalate resin fragments, antioxidants, flame retardants, and reinforcing agents are then dried. The dried antioxidants, flame retardants, reinforcing agents, and polybutylene terephthalate resin fragments are added to a high-speed mixer and mixed at a certain temperature for 18-20 minutes to obtain a mixture.

[0017] S3: Melt molding: The obtained mixture is placed in a twin-screw extruder for melt blending. The temperature of the twin-screw extruder is 245℃~255℃, the speed of melt blending is 270~300rpm, and the melt pressure of melt blending is 6.1~6.8MPa.

[0018] Note: The transesterification method for synthesizing polyester can be carried out intermittently or continuously, making it easy to operate. The equipment used is relatively simple, the reaction conditions are relatively mild, and the reaction is easy to control. Furthermore, the addition of a titanium catalyst can improve the reaction efficiency, resulting in a higher quality polybutylene terephthalate resin masterbatch. Dry mixing ensures that the components are as dry as possible before molding, preventing hydrolysis of the polybutylene terephthalate resin during melt blending. By setting the melt parameters, the average mass of the polybutylene terephthalate resin particles is maintained between 3 mg and 9 mg / particle.

[0019] Furthermore, in step S1, the reactor temperature gradually increases at a rate of 10℃~15℃ / min, the stirring rate is 50~150rpm, and the decompression rate is 1~1.5kPa / min;

[0020] Note: A heating rate of 10℃~15℃ / min is suitable. Temperatures below this range will result in lower reaction efficiency, while temperatures above this range will affect the polymerization effect. A stirring rate of 50~150rpm is preferable. Temperatures below this range will result in incomplete reaction, while temperatures above this range will not have a better effect on the polymerization reaction and may even affect it. A decompression rate of 1~1.5kPa / min is preferred, as it can be combined with temperature to promote the polycondensation process. Therefore, under the above conditions, the esterification rate of the esterification reaction is better.

[0021] Furthermore, in step S1, the titanium catalyst is added intermittently, specifically 5-8% of the total mass of the titanium catalyst is added for every 3-5°C increase in reactor temperature.

[0022] Note: The above-mentioned method of adding titanium catalyst can promote the polycondensation of butylene terephthalate oligomers, thereby maximizing the catalytic effect of titanium catalyst.

[0023] Furthermore, the mixing step in step S2 is as follows:

[0024] S2-1: Drying treatment: Dry the polybutylene phthalate resin fragments, antioxidants, flame retardants, and reinforcing agents at 50℃~70℃ for 1~2h;

[0025] S2-2: Take half of the total mass of polybutylene terephthalate resin fragments, freeze them, and then grind them into powder for later use; the freezing temperature is -120℃~-70℃, the pressure is 0.2MPa, the freezing time is 5-10min, and the powder is ground into polybutylene terephthalate resin powder with a D50 of 200~400μm.

[0026] S2-3: Mix the remaining polybutylene terephthalate resin fragments with flame retardant and reinforcing agent to form a mixture, heat the mixture to 80-90℃, and keep it at that temperature for later use;

[0027] S2-4: Mix the polybutylene terephthalate resin powder and the mixture from step S2-2 in a high-speed mixer at 450-500 rpm until the polybutylene terephthalate resin powder and the mixture reach the same temperature, then heat to 160℃-180℃.

[0028] Explanation: By stirring and heating half of the polybutylene terephthalate (PET) resin powder together with the mixture, the two can be thoroughly mixed, allowing the PET resin powder to be evenly distributed on the mixture. Furthermore, by heating the two together under a temperature difference, the PET resin retains its fragmented characteristics while the components undergo a preliminary melt blending reaction. This results in a PET resin material with high viscosity, good uniformity, and excellent mechanical and electrical properties, leading to high product quality.

[0029] The beneficial effects of this invention are:

[0030] (1) The titanium ammonium lactate chelate catalyst used in this invention can overcome the disadvantage of tetrabutyl titanate being intolerant to hydrolysis, and has good catalytic activity, is resistant to hydrolysis, easy to store, and has stable properties. It solves the problem of low reaction rate caused by the hydrolysis resistance of tetrabutyl titanate, which is common in PBT resin production. It eliminates the weakness of titanium oxyester bond being easily attacked by water, while retaining the activity of titanium. Using ammonium lactate as a ligand, the titanium chelate can exist stably in water, while increasing the adhesion and improving the surface hardness.

[0031] (2) The present invention adopts a freeze-mixing process, which can make the polybutylene terephthalate resin powder evenly distributed on the mixture. By raising the temperature of both under the temperature difference, the polybutylene terephthalate resin retains the fragment characteristics while each component undergoes a preliminary melt-blending reaction, resulting in a polybutylene terephthalate resin material with higher viscosity, better uniformity, and excellent mechanical and electrical properties, resulting in higher product quality.

[0032] (3) By setting the addition of titanium catalyst in esterification and polycondensation, the present invention significantly improves the hydrolysis resistance of PBT. Furthermore, by setting the production method, the anti-aging properties, tensile properties, and flame retardant properties of the produced PBT are all optimized. At the same time, the present invention uses siloxane oligomers in silicon-based flame retardants as flame retardants, which can achieve both flame retardancy and dispersion, improve mechanical and electrical properties, and increase chemical resistance and impact strength. The use of a mixed powder of antioxidant 1010 and antioxidant 168 in a ratio of 11:2 can further improve the stability of polyester, thereby better inhibiting PBT aging. The use of SEBS-g-MAH copolymer as a toughening agent can better improve the mechanical properties of PBT. Detailed Implementation

[0033] The present invention will now be described in more detail with reference to specific embodiments, so as to better demonstrate the advantages of the present invention.

[0034] Example 1

[0035] A polybutylene terephthalate resin granule, which is a granule of a polybutylene terephthalate resin composition, wherein the granule comprises, by weight, 43 parts of terephthalic acid, 48 parts of 1,4-butanediol, 0.6 parts of titanium catalyst, 3 parts of flame retardant, 0.6 parts of reinforcing agent and 3 parts of antioxidant.

[0036] The titanium catalyst is a titanium ammonium lactate chelate, and the preparation steps of the titanium ammonium lactate chelate are as follows:

[0037] 1) Lactic acid and ammonia were stirred and reacted at room temperature for 1.5 h to obtain an ammonium lactate solution; wherein the mass ratio of lactic acid to ammonia was 2:1.

[0038] 2) Add titanate to an aluminum hydroxide solution with pH 9.2, and stir the reaction at 40°C for 2 hours before cooling to room temperature to obtain an alkaline solution; wherein the mass ratio of titanate to aluminum hydroxide in the aluminum hydroxide solution is 2:5.

[0039] 3) Add ammonium lactate solution dropwise to the alkaline solution at a rate of 8 drops / min, while continuously stirring and heating from room temperature to 80°C. Once the pH reaches 8.8, add ammonium lactate solution dropwise at a rate of 20 drops / min, stirring until all the water in the alkaline solution has evaporated. Then cool to room temperature to obtain the titanium catalyst. The mass ratio of ammonium lactate solution to alkaline solution is 2:3, and each drop of solution is 0.05 ml.

[0040] The flame retardant is a siloxane oligomer among silicon-based flame retardants; the reinforcing agent is a mixture of EPDM-g-MAH and POE-g-MAH at a mass ratio of 5:2; and the antioxidant is a mixed powder of antioxidant 1010 and antioxidant 168 at a mass ratio of 11:2.

[0041] A method for producing polybutylene terephthalate resin particles includes the following steps:

[0042] S1: Synthesizing polyester: Terephthalic acid and 1,4-butanediol are placed in a reactor. The reactor temperature is gradually increased from room temperature (25℃) to 210℃, and the pressure is maintained at atmospheric pressure. Terephthalic acid and 1,4-butanediol undergo esterification reaction. Titanium catalyst is intermittently added to the reactor. After stirring for 150 min, the reactor pressure is reduced to 80 Pa, and the temperature is adjusted to 252℃. Polycondensation is carried out for 130 min to synthesize polybutylene terephthalate resin masterbatch. The reactor temperature is gradually increased at a rate of 12℃ / min, the stirring rate is 100 rpm, the pressure reduction rate is 1.2 kPa / min, and the titanium catalyst is intermittently added at a rate of 6% of the total mass of titanium catalyst for every 4℃ increase in reactor temperature.

[0043] S2: Drying and Mixing: After cooling the polybutylene terephthalate resin masterbatch to room temperature, it is pulverized into polybutylene terephthalate resin fragments, and the polybutylene terephthalate resin fragments, antioxidants, flame retardants, and reinforcing agents are dried; S2-1: Drying Treatment: The polybutylene terephthalate resin fragments, antioxidants, flame retardants, and reinforcing agents are dried at 60℃ for 1.5h;

[0044] S2-2: Take half of the total mass of polybutylene terephthalate resin fragments, freeze them, and then grind them into powder for later use; the freezing temperature is -100℃, the pressure is 0.2MPa, the freezing time is 8min, and the powder is ground into polybutylene terephthalate resin powder with a D50 of 300μm.

[0045] S2-3: Mix the remaining polybutylene terephthalate resin fragments with antioxidants, flame retardants, and reinforcing agents to form a mixture. Heat the mixture to 85°C and keep it warm until ready for use.

[0046] S2-4: Mix the polybutylene terephthalate resin powder and the mixture in a high-speed mixer at 480 rpm until the polybutylene terephthalate resin powder and the mixture reach the same temperature. Then, heat the mixture to 170°C and mix it in the high-speed mixer for 19 minutes to obtain the mixture.

[0047] S3: Melt Molding: The obtained mixture is placed in a twin-screw extruder for melt blending. The temperature of the twin-screw extruder is 250℃, the speed of melt blending is 280rpm, and the melt pressure of melt blending is 6.5MPa.

[0048] Example 2

[0049] The difference between this embodiment and Example 1 is that the weight proportions of the raw materials in the polybutylene terephthalate resin composition are different. Specifically, it consists of: 40 parts terephthalic acid, 45 parts 1,4-butanediol, 0.5 parts titanium catalyst, 2 parts flame retardant, 0.4 parts reinforcing agent, and 1 part antioxidant. The reinforcing agent is a mixture of EPDM-g-MAH and POE-g-MAH in a mass ratio of 2:1. The antioxidant is a mixed powder of antioxidant 1010 and antioxidant 168 in a mass ratio of 5:1.

[0050] Example 3

[0051] The difference between this embodiment and Example 1 is that the weight proportions of the raw materials in the polybutylene terephthalate resin composition are different. Specifically, it consists of 45 parts terephthalic acid, 50 parts 1,4-butanediol, 0.8 parts titanium catalyst, 4 parts flame retardant, 0.8 parts reinforcing agent, and 5 parts antioxidant. The reinforcing agent is a mixture of EPDM-g-MAH and POE-g-MAH in a mass ratio of 3:1. The antioxidant is a mixed powder of antioxidant 1010 and antioxidant 168 in a mass ratio of 6:1.

[0052] Example 4

[0053] The difference between this embodiment and Example 1 is that the titanium catalyst preparation components are different. Specifically, in step 2), tetrabutyl titanate is added to aluminum hydroxide solution in a ratio of 1:2 to obtain an alkaline solution; in step 3), ammonium lactate solution is added to the above alkaline solution in a ratio of 1:1 to obtain the titanium catalyst.

[0054] Example 5

[0055] The difference between this embodiment and Example 1 is that the titanium catalyst preparation components are different. Specifically, in step 2), tetrabutyl titanate is added to aluminum hydroxide solution in a ratio of 1:3 to obtain an alkaline solution; in step 3), ammonium lactate solution is added to the above alkaline solution in a ratio of 1:2 to obtain the titanium catalyst.

[0056] Example 6

[0057] The difference between this embodiment and Example 1 is that the preparation conditions and parameters of the titanium catalyst are different. Specifically, in step 2), tetrabutyl titanate is added to an aluminum hydroxide solution with a pH of 9.0, and the mixture is stirred at 30°C for 3 hours to react before being cooled to room temperature to obtain an alkaline solution; in step 3), ammonium lactate solution is added to the above alkaline solution, and the mixture is continuously stirred and heated from room temperature to 70°C.

[0058] Example 7

[0059] The difference between this embodiment and Example 1 is that the preparation conditions and parameters of the titanium catalyst are different. Specifically, in step 2), tetrabutyl titanate is added to an aluminum hydroxide solution with a pH of 9.3, and the mixture is stirred at 50°C for 1 hour to react before being cooled to room temperature to obtain an alkaline solution; in step 3), ammonium lactate solution is added to the above alkaline solution, and the mixture is continuously stirred and heated from room temperature to 90°C.

[0060] Example 8

[0061] The difference between this embodiment and Example 1 is that the pH is different in the preparation of the titanium catalyst. Specifically, after the pH reaches 8.7 in step 3), the rate of increase of the ammonium lactate solution is increased.

[0062] Example 9

[0063] The difference between this embodiment and Example 1 is that the pH is different in the preparation of the titanium catalyst. Specifically, after the pH reaches 8.9 in step 3), the rate of increase of the ammonium lactate solution is increased.

[0064] Example 10

[0065] The difference between this embodiment and Embodiment 1 is that the dropping rate of the ammonium lactate solution in the preparation of the titanium catalyst is different. Specifically, in step 3), the ammonium lactate solution is added to the alkaline solution at a rate of 5 drops / min. After the pH reaches 8.8, the ammonium lactate solution is added at a rate of 30 drops / min.

[0066] Example 11

[0067] The difference between this embodiment and Example 1 is that the dropping rate of the ammonium lactate solution in the preparation of the titanium catalyst is different. Specifically, in step 3), the ammonium lactate solution is added to the alkaline solution at a rate of 10 drops / min. After the pH reaches 8.8, the ammonium lactate solution is added at a rate of 15 drops / min.

[0068] Example 12

[0069] The difference between this embodiment and Embodiment 1 is that the temperature and stirring parameters are different in the production method of polybutylene terephthalate resin particles. Specifically, in step S1, the reactor temperature is gradually increased to 205°C at a heating rate of 10°C / min, and stirred for 100min. Then, when the reactor pressure is reduced to 80Pa, the temperature is adjusted to 250°C. Polycondensation is carried out for 100min to synthesize polybutylene terephthalate resin masterbatch, and the stirring rate is 50rpm.

[0070] Example 13

[0071] The difference between this embodiment and Embodiment 1 is that the temperature and stirring parameters are different in the production method of polybutylene terephthalate resin particles. Specifically, in step S1, the reactor temperature is gradually increased to 220°C at a heating rate of 15°C / min, and stirred for 180min. Then, when the reactor pressure is reduced to 80Pa, the temperature is adjusted to 255°C. Polycondensation is carried out for 160min to synthesize polybutylene terephthalate resin masterbatch, and the stirring rate is 150rpm.

[0072] Example 14

[0073] The difference between this embodiment and Embodiment 1 is that the parameters in steps S2 and S3 are different. Specifically, in step S2-1, the mixture is dried at 50°C for 1 hour; in step S2-4, the mixture is stirred at 450 rpm in a high-speed mixer for 18 minutes to obtain the mixture; in step S3, the molding process involves a twin-screw extruder with a machine temperature of 245°C, a melt blending speed of 270 rpm, and a melt pressure of 6.1 MPa.

[0074] Example 15

[0075] The difference between this embodiment and Embodiment 1 is that the parameters in steps S2 and S3 are different. Specifically, in step S2-1, the mixture is dried at 70°C for 1 hour; in step S2-4, the mixture is stirred at 500 rpm in a high-speed mixer for 20 minutes to obtain the mixture; in step S3, the molding process involves a twin-screw extruder with a machine temperature of 255°C, a melt blending speed of 300 rpm, and a melt pressure of 6.8 MPa.

[0076] Example 16

[0077] The difference between this embodiment and embodiment 1 is that the mixing and freezing parameters in step S2 are different. Specifically, in step S2-2, the freezing temperature is -120℃, the freezing time is 5min, and the polybutylene terephthalate resin powder is ground to a D50 of 300μm.

[0078] Example 17

[0079] The difference between this embodiment and embodiment 1 is that the freezing parameters in step S2 are different. Specifically, in step S2-2, the freezing temperature is -70℃, the freezing time is 10min, and the polybutylene terephthalate resin powder with a D50 of 350μm is ground.

[0080] Example 18

[0081] The difference between this embodiment and embodiment 1 is that the temperature in step S2 is different. Specifically, in S2-3, the mixture is heated to 80°C.

[0082] Example 19

[0083] The difference between this embodiment and embodiment 1 is that the temperature in step S2 is different. Specifically, in S2-3, the mixture is heated to 90°C.

[0084] Example 20

[0085] The difference between this embodiment and embodiment 1 is that the temperature in step S2 is different. Specifically, in S2-4, after the polybutylene terephthalate resin powder and the mixture are heated to the same temperature, the temperature is raised to 160°C.

[0086] Example 21

[0087] The difference between this embodiment and embodiment 1 is that the temperature in step S2 is different. Specifically, in S2-4, after the polybutylene terephthalate resin powder and the mixture are heated to the same temperature, the temperature is raised to 180°C.

[0088] Example 22

[0089] The difference between this embodiment and Example 1 is that the titanium catalyst is added in step S1 in a different way. Specifically, 5% of the total mass of titanium catalyst is added for every 3°C increase in reactor temperature.

[0090] Example 23

[0091] The difference between this embodiment and Embodiment 1 is that the titanium catalyst is added in step S1 in a different way. Specifically, 8% of the total mass of the titanium catalyst is added for every 5°C increase in reactor temperature.

[0092] Experimental Example

[0093] In this invention, intrinsic viscosity and hydrolysis resistance are tested using the following methods:

[0094] Intrinsic viscosity: Measured using an Ubbelohde viscometer at 25°C;

[0095] Hydrolysis resistance: The test was conducted in a constant temperature and humidity chamber with a constant temperature of 90℃ and a constant humidity of 95% for 70 hours of continuous aging. After aging, the change rate of terminal carboxyl groups and intrinsic viscosity of the product was measured. The change rate of intrinsic viscosity was: (intrinsic viscosity before aging - intrinsic viscosity after aging) / intrinsic viscosity before aging × 100%.

[0096] 1. To investigate the effects of different raw material components on the intrinsic viscosity, hydrolysis resistance, and flame retardant properties of the produced polybutylene terephthalate resin particles;

[0097] Examples 1, 2, and 3 were used for experimental comparison, and the results are shown in Table 1 below:

[0098] Table 1. Effects of different raw material components on the viscosity characteristics, viscosity change rate, and flame retardant properties of the produced polybutylene terephthalate resin particles before aging.

[0099] Example 1 1.21 1.75％ Example 2 1.15 1.97％ Example 3 1.17 2.21％

[0100] As can be seen from Table 1, compared with Examples 1, 2 and 3, the polybutylene terephthalate resin particles produced by the raw material components of Example 1 have a better intrinsic viscosity and better resistance to aging and hydrolysis.

[0101] 2. To investigate the effects of different titanium catalyst preparation components on the intrinsic viscosity and hydrolysis resistance of the produced polybutylene terephthalate resin particles;

[0102] Experimental Example 1 was set up. In Experimental Example 1, tetrabutyl titanate was added to step S1 as a titanium catalyst, and the other components were the same as in Example 1.

[0103] Comparative Example 1 was set up, and the organic chelated hydrolysis-resistant catalyst disclosed in patent CN111484608A was used as a titanium catalyst in step S1. The remaining components were the same as in Example 1.

[0104] Examples 1, 4, 5, Comparative Example 1, and Experimental Example 1 were used for experimental comparison, and the results are shown in Table 2 below:

[0105] Table 2. Effects of different titanium catalyst components on the intrinsic viscosity and intrinsic viscosity change rate of the produced polybutylene terephthalate resin particles before aging.

[0106]

[0107]

[0108] As can be seen from Table 2, compared with Examples 1, 4, and 5, the intrinsic viscosity of the polybutylene terephthalate resin particles produced by the titanium catalyst component used in Example 1 is more preferred, and the aging and hydrolysis resistance is better. Compared with Example 1 and Experimental Example 1, it can be concluded that the addition of unchelated titanium catalyst in Experimental Example 1 not only reduced the intrinsic viscosity, but also resulted in poor hydrolysis resistance, which is significantly different from that of Example 1. Compared with Example 1 and Comparative Example 1, it can be concluded that Example 1 is more preferred.

[0109] 3. Investigate the effects of different titanium catalyst preparation conditions on the intrinsic viscosity and hydrolysis resistance of the produced polybutylene terephthalate resin particles;

[0110] Examples 1, 6, and 7 were used for experimental comparison, and the results are shown in Table 3 below:

[0111] Table 3. Effects of different titanium catalyst preparation temperatures on the intrinsic viscosity and intrinsic viscosity change rate of the produced polybutylene terephthalate resin particles before aging.

[0112] Example 1 1.21 1.75％ Example 6 1.17 1.99％ Example 7 1.16 1.80％

[0113] As can be seen from Table 3, compared with Examples 1, 6 and 7, the polybutylene terephthalate resin particles produced in Example 1 have a better intrinsic viscosity and better resistance to aging and hydrolysis.

[0114] 4. Investigate the effect of pH adjustment of different titanium catalysts on the intrinsic viscosity and hydrolysis resistance of the produced polybutylene terephthalate resin particles;

[0115] In Comparative Example 2, in step 3) of the preparation of the titanium catalyst, ammonium lactate solution was completely added to the alkaline solution at a constant rate of 12 drops / min, and the remaining steps were the same as in Example 1.

[0116] Examples 1, 8, and 9, and Comparative Example 2 were used for experimental comparison, and the results are shown in Table 4 below:

[0117] Table 4. Effects of pH adjustment with different titanium catalysts on the intrinsic viscosity and intrinsic viscosity change rate of the produced polybutylene terephthalate resin particles before aging.

[0118] Example 1 1.21 1.75％ Example 8 1.18 2.01％ Example 9 1.16 1.89％ Comparative Example 2 1.08 2.54％

[0119] As can be seen from Table 4, compared with Examples 1, 8 and 9, the polybutylene terephthalate resin particles in Example 1 are more preferred. Compared with Examples 1 and 2, the titanium catalyst prepared by constant-rate dropwise addition of ammonium lactate solution in Comparative Example 2 is less effective than that in Example 1. Therefore, Example 1 is more preferred.

[0120] 5. Investigate the effect of different titanium catalysts and ammonium lactate solution dropping rates on the intrinsic viscosity and hydrolysis resistance of the produced polybutylene terephthalate resin particles;

[0121] Examples 1, 10, and 11 were used as comparative experiments, and the results are shown in Table 5 below:

[0122] Table 5. Effects of different titanium catalyst ammonium lactate solution dropping rates on the intrinsic viscosity and intrinsic viscosity change rate of the produced polybutylene terephthalate resin particles before aging.

[0123] Example 1 1.21 1.75％ Example 10 1.16 2.11％ Example 11 1.15 2.07％

[0124] As can be seen from Table 5, the dropping rate of ammonium lactate solution with different titanium catalysts has an impact on intrinsic viscosity and hydrolysis resistance, and Example 1 is more preferred.

[0125] 6. Investigate the effects of different temperatures and stirring parameters on the intrinsic viscosity and hydrolysis resistance of the produced polybutylene terephthalate resin particles;

[0126] Examples 1, 12, and 13 were used as experimental comparisons, and the results are shown in Table 6 below:

[0127] Table 6. Effects of different temperatures and stirring parameters on the intrinsic viscosity and intrinsic viscosity change rate of the produced polybutylene terephthalate resin particles before aging.

[0128] Example 1 1.21 1.75％ Example 12 1.17 1.80％ Example 13 1.22 1.76％

[0129] As can be seen from Table 6, different temperatures and stirring parameters in step S1 have an impact on intrinsic viscosity and hydrolysis resistance. The intrinsic viscosity of Example 13 is better, but it is not much different from that of Example 1. Moreover, the rate of change of intrinsic viscosity is slightly larger than that of Example 1. Considering the economic efficiency of the production process, Example 1 is preferred.

[0130] 7. Investigate the effects of different production parameters on the intrinsic viscosity and hydrolysis resistance of polybutylene terephthalate resin particles;

[0131] Examples 1, 14, 15, 22, and 23 were used for experimental comparison, and the results are shown in Table 7 below:

[0132] Table 7. Effects of different production parameters on the intrinsic viscosity and intrinsic viscosity change rate of the produced polybutylene terephthalate resin particles before aging.

[0133] Example 1 1.21 1.75％ Example 14 1.18 1.80％ Example 15 1.20 1.75％ Example 22 1.16 1.78％ Example 23 1.17 1.74％

[0134] As can be seen from Table 7, different production parameters in steps S2 and S3 have an impact on intrinsic viscosity and hydrolysis resistance. It can be seen that Example 1 and Example 15 are more preferred. Based on the economics of the production process, Example 1 is preferred.

[0135] Comparing Examples 1, 22, and 23, it can be seen that the different ways of adding titanium catalyst in step S1 affect the intrinsic viscosity. Although Example 23 has a reduced intrinsic viscosity change rate, which can improve hydrolysis resistance, its intrinsic viscosity is not as good as that of Example 1. Overall, Example 1 is more preferred.

[0136] 8. Investigate the effects of different freezing and mixing parameters on the intrinsic viscosity and hydrolysis resistance of the produced polybutylene terephthalate resin fragments.

[0137] Comparative Example 3 was set up. In step S2, the polybutylene phthalate resin fragments, antioxidants, flame retardants, and reinforcing agents were dried at 60°C for 1.5 hours, heated to 170°C, and mixed in a high-speed mixer for 19 minutes. The rest of the process was the same as in Example 1.

[0138] Examples 1, 16, 17, 18, 19, and 20, as well as Comparative Example 3, were used for experimental comparison. The results are shown in Table 8 below:

[0139] Table 8. Effects of the method and rate of addition of titanium catalyst and flame retardant on the intrinsic viscosity and intrinsic viscosity change rate of the produced polybutylene terephthalate resin particles before aging.

[0140] Example 1 1.21 1.75％ Example 16 1.20 1.87％ Example 17 1.19 1.80％ Example 18 1.18 1.81％ Example 19 1.19 1.79％ Example 20 1.20 1.95％ Example 21 1.19 1.91％ Comparative Example 3 0.78 4.96％

[0141] As can be seen from Table 8, compared with Examples 16, 17, 18, 19, 20 and 21, Example 1 shows a smaller change in intrinsic viscosity and stronger hydrolysis resistance, making it a preferred choice. Comparing Example 1 with Comparative Example 3, it can be concluded that the freeze-mixing treatment in step S2 has a significant impact on the intrinsic viscosity and viscosity change rate of the polybutylene terephthalate resin particles. Therefore, Example 1 is a preferred choice.

[0142] 9. Investigate the effects of different production parameters on the tensile strength and flame retardant properties of the produced polybutylene terephthalate resin particles;

[0143] Tensile / Elongation at break: Polybutylene terephthalate resin particles were processed into standard test specimens using the same process and tested using a computer-controlled electronic universal testing machine WOT-10GB / 1040.

[0144] Combustion performance: Vertical combustion performance was tested according to the US UL94 standard.

[0145] Comparative Example 4 was set up, in which no flame retardant was added and the remaining components were the same as those in Example 1;

[0146] Comparative Examples 1, 2, 3, and 4 were used for experimental comparison, and the results are shown in Table 8 below:

[0147] Table 9. Tensile strength and flame retardant properties of polybutylene terephthalate resin particles produced under different production parameters.

[0148] Example 1 38 32％ V-1 Comparative Example 1 42 24％ V-1 Comparative Example 2 43 29％ V-1 Comparative Example 3 45 12％ V-2 Comparative Example 4 45 27％ Does not meet Level V criteria

[0149] As can be seen from Table 9, through comparison, the tensile toughness and flame retardant properties of Example 1 are more preferred. The settings in Comparative Example 2 have a certain impact on tensile strength and elongation at break. The settings in Comparative Example 3 have a greater impact on tensile toughness. The flame retardant properties in Comparative Example 4 are poor.

Claims

1. A type of polybutylene terephthalate resin granules, characterized in that, It is a granule of polybutylene terephthalate resin composition, wherein the granules comprise, by weight parts: 40-45 parts of terephthalic acid, 45-50 parts of 1,4-butanediol, 0.5-0.8 parts of titanium catalyst, 2-4 parts of flame retardant, 0.4-0.8 parts of reinforcing agent, and 1-5 parts of antioxidant. The titanium catalyst is a titanium ammonium lactate chelate, and the preparation steps of the titanium ammonium lactate chelate are as follows: 1) Stir lactic acid and ammonia water at room temperature for 1-2 hours to obtain ammonium lactate solution; wherein the mass ratio of lactic acid to ammonia water is 2:1; 2) Add titanate to an aluminum hydroxide solution with a pH of 9.0–9.3, and stir the reaction at 30–50°C for 1–3 hours, then cool to room temperature to obtain an alkaline solution; wherein the mass ratio of titanate to aluminum hydroxide in the aluminum hydroxide solution is 1:2–3. 3) Add ammonium lactate solution dropwise to the alkaline solution at a rate of 5-10 drops / min, while continuously stirring and heating from room temperature to 70-90°C. Once the pH reaches 8.7-8.9, add ammonium lactate solution dropwise at a rate of 15-30 drops / min, stirring until all the water in the alkaline solution has evaporated. Then cool to room temperature to obtain the titanium catalyst. The mass ratio of ammonium lactate solution to alkaline solution is 1:1-2. A method for producing polybutylene terephthalate resin granules includes the following steps: S1: Synthetic polyester. Terephthalic acid and 1,4-butanediol are placed in a reactor. The reactor temperature is gradually increased from room temperature to 205℃~220℃. Under normal pressure, terephthalic acid and 1,4-butanediol undergo esterification reaction. Titanium catalyst is intermittently added to the reactor. After stirring for 100~180min, the reactor pressure is reduced to 70Pa~90Pa, and the temperature is adjusted to 250℃~255℃. Polycondensation is carried out for 100~160min to synthesize polybutylene terephthalate resin masterbatch. S2: Drying and Mixing: After cooling the polybutylene terephthalate resin masterbatch to room temperature, it is pulverized into polybutylene terephthalate resin fragments. The polybutylene terephthalate resin fragments, antioxidants, flame retardants, and reinforcing agents are then dried. The dried antioxidants, flame retardants, reinforcing agents, and polybutylene terephthalate resin fragments are added to a high-speed mixer and mixed at a certain temperature for 18-20 minutes to obtain a mixture. The mixing steps are as follows: S2-1: Drying treatment: Dry the polybutylene phthalate resin fragments, antioxidants, flame retardants, and reinforcing agents at 50℃~70℃ for 1~2h; S2-2: Take half of the total mass of dried polybutylene terephthalate resin fragments, freeze them, and then grind them into powder for later use; the freezing temperature is -120℃~-70℃, the pressure is 0.2MPa, the freezing time is 5-10min, and the powder is ground into polybutylene terephthalate resin powder with a D50 of 300~350μm; S2-3: Mix the remaining polybutylene terephthalate resin fragments with flame retardant and reinforcing agent to form a mixture, heat the mixture to 80-90℃, and keep it at that temperature for later use; S2-4: Mix the polybutylene terephthalate resin powder and the mixture in a high-speed mixer at 450-500 rpm until the polybutylene terephthalate resin powder and the mixture are at the same temperature, then heat to 160℃-180℃. S3: Melt molding: The obtained mixture is placed in a twin-screw extruder for melt blending. The temperature of the twin-screw extruder is 245℃~255℃, the speed of melt blending is 270~300rpm, and the melt pressure of melt blending is 6.1~6.8MPa.

2. The polybutylene terephthalate resin particles as described in claim 1, characterized in that, The flame retardant is a silicon-based flame retardant; the reinforcing agent is a mixture of EPDM-g-MAH and POE-g-MAH at a mass ratio of 2 to 3:1; and the antioxidant is a mixed powder of antioxidant 1010 and antioxidant 168 at a mass ratio of 5 to 6:

1.

3. The polybutylene terephthalate resin particles as described in claim 1, characterized in that, The polybutylene terephthalate resin particles have an intrinsic viscosity of 1.15–1.25 dl / g and an average mass of 3–9 mg / particle.

4. The method for producing polybutylene terephthalate resin particles as described in claim 1, characterized in that, In step S1, the reactor temperature gradually increases at a rate of 10℃~15℃ / min, the stirring rate is 50~150rpm, and the decompression rate is 1~1.5kPa / min.

5. The method for producing polybutylene terephthalate resin particles as described in claim 1, characterized in that, Step S1 involves intermittently adding titanium catalyst, specifically by adding 5-8% of the total mass of titanium catalyst for every 3-5°C increase in reactor temperature.

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