Low-shrinkage elastomer toughened PBT material

Abstract

The invention discloses a low-shrinkage elastomer toughened PBT (polybutylene terephthalate) material, and relates to the technical field of PBT materials, and a preparation method of the low-shrinkage elastomer toughened PBT material comprises the following steps: S1, raw material preparation: respectively pretreating a composite toughening agent, a low-shrinkage elastomer and PBT, s2, preparation of a premix: adding the PBT, the low-shrinkage elastomer, the composite toughening agent, the composite compatilizer, the lubricant and the ultraviolet stabilizer pretreated in the step S1 into a high-speed mixer according to a ratio, and premixing. According to the invention, the toughening agent is pretreated in a manner of combining plasma treatment and surface active agent coating, the plasma treatment is firstly carried out, and then the surface active agent coating is carried out, so that one end of the surface active agent is adsorbed on the surface of the toughening agent, and the interaction manner of the toughening agent and the PBT material is changed by the other end of the surface active agent; and the compatibility of the toughening agent and the PBT material is improved from different angles through the combination of the toughening agent and the PBT material, so that the contractibility and toughness of the finally prepared product are improved.

Description

Technical Field

[0001] The invention relates to the technical field of PBT materials, in particular to a low-shrinkage elastomer toughened PBT material. Background Art

[0002] The full name of PBT material is polybutylene terephthalate, which is a high-performance thermoplastic polyester with the characteristics of high strength, good fatigue resistance, dimensional stability, excellent insulation performance, self-lubrication and excellent wear resistance. PBT material is widely used in electronic appliances, automobiles, mechanical equipment and medical equipment. The shrinkage and toughness of existing PBT materials are difficult to achieve the best use effect at the same time.

[0003] The defects of existing PBT materials are: Patent document CN111073233B discloses a high-toughness PBT composite material and its preparation method and application. It mainly considers how to further improve the compatibility and toughness, further enhance the performance of the PBT material, so that the composite material has more excellent performance, but does not consider how to simultaneously improve the shrinkage and toughness of the PBT material; Patent document CN110423438B discloses a high-gloss and high-toughness PBT modified material and its preparation method, which mainly considers how to make the prepared PBT modified material have good fluidity, high gloss and excellent comprehensive performance, but does not consider how to reduce the shrinkage rate of the PBT material while improving the internal structure of the material; Patent document CN115651375B discloses a halogen-containing flame-retardant PBT material and its preparation method and application. It mainly considers how to make the PBT material have excellent flame retardancy and CTI performance, but does not consider how to increase the toughness and impact resistance of the PBT material while improving the rigidity, hardness and tensile strength of the PBT material; Patent document CN114736495B discloses a carbon fiber reinforced PBT material and its preparation method. It mainly considers how to make the PBT material have good wear resistance, excellent mechanical strength and high warping resistance, but does not consider how to help reduce the phase separation phenomenon and thus improve the overall performance of the PBT material. Summary of the invention

[0004] The object of the present invention is to provide a low shrinkage elastomer toughened PBT material to solve the problems raised in the above background technology.

[0005] To achieve the above object, the present invention provides the following technical solutions: a low shrinkage elastomer toughened PBT material, and a method for preparing the low shrinkage elastomer toughened PBT material, comprising the following steps: Step S1: raw material preparation: pre-treating the composite toughening agent, low shrinkage elastomer and PBT respectively; Step S2: Premix preparation: the PBT, low shrinkage elastomer, composite toughening agent, composite compatibilizer, lubricant and UV stabilizer pretreated in step S1 are sequentially added into a high-speed mixer in a mass ratio of (60-70): (15-25): (4-8): (8-9): (0.5-1.5): (0.2-0.6) for premixing to obtain a premix; Step S3: extrusion granulation: the mixed premix is ​​extruded and granulated through a twin-screw extruder to obtain low shrinkage elastomer toughened PBT material particles; Step S4: injection molding: adding the low shrinkage elastomer toughened PBT material particles prepared in step S3 into an injection molding machine for injection molding, wherein the mold temperature is 50-60° C., the injection pressure is 60-80 MPa, the holding pressure is 20-40 MPa, the injection speed is 60 mm / s, the mold opening speed is 30 mm / s, and the mold closing speed is 20 mm / s; Step S5: post-processing: post-processing the injection molded low shrinkage elastomer toughened PBT material particles; Step S6: Performance test: Performing performance test on the prepared low shrinkage elastomer toughened PBT material; In step S1, the following steps are also included: Step S11: toughening agent pretreatment: the composite toughening agent is placed in the reaction chamber of the plasma treatment equipment, oxygen is introduced at a flow rate of 50-80sccm, and the treatment is carried out for 5-10min at a power of 200-300W. The high-energy particles interact with the surface of the composite toughening agent, polar functional groups are introduced on the surface, and active sites are increased. Then, the composite toughening agent after plasma treatment is added to the surfactant solution for coating. The amphiphilic structure of the surfactant adsorbs on the surface of the composite toughening agent at one end, and changes the subsequent interaction mode between the composite toughening agent and the PBT material at the other end. Stir for 2-6h at 20-30°C and a speed of 200-400rpm, wherein the volume ratio of the surfactant solution to the composite toughening agent is (2-5):100, and then filter it, then wash it with deionized water, and place it in a vacuum box at a temperature of 50-60°C for 3-6h.

[0006] Preferably, in step S1, the following steps are also included: Step S12: PBT pretreatment: placing the PBT resin in a forced air drying oven at 150-160° C. for 2-3 hours, and then screening the PBT using a vibrating screen with a 90-mesh screen; Step S13: PBT modification: adding the pretreated PBT, composite filler, lubricant and antioxidant into the hopper of a twin-screw extruder in a ratio of (50-60): (20-30): 0.2: 0.1, and mixing for 10-40 minutes at a screw speed of 240-340 rpm and a temperature of 220-240°C; Step S14: Pretreatment of low shrinkage elastomer: Use a vacuum drying oven to dry the low shrinkage elastomer, wherein the drying temperature is 70°C and the drying time is 5-6h. Then, use a grinder to crush the low shrinkage elastomer at a rotation speed of 200-300rpm and a crushing time of 30-60min. Then, use a screening device to screen out the particle size of 50-100μm.

[0007] Preferably, in step S2, the following steps are also included: Step S21: firstly add PBT, low shrinkage elastomer, composite toughening agent, composite compatibilizer and lubricant into a high-speed mixer, and stir and mix them at a speed of 800-1200 rpm for 5-30 minutes to obtain a primary mixture; Step S22: Then, add the ultraviolet stabilizer into the high-speed mixer, and continue stirring at a speed of 600-800 rpm for 2-15 minutes to obtain a premix.

[0008] Preferably, in step S3, the following steps are also included: Step S31: feeding the premix into a twin-screw extruder, blending at a speed of 120-140 rpm for 2-3 min at a temperature of 25-35° C., then raising the temperature to 240-250° C. and blending at a speed of 350-400 rpm for 2-10 min; Step S32: The particles extruded in step S31 are cooled by water cooling, wherein the water temperature is 10-20°C, the water flow rate is 1-1.5 m / s, and the treatment is carried out for 20-40 min. Then, the particles are sent to a hot air drying oven and dried at a temperature of 30-50°C for 10-40 min.

[0009] Preferably, in step S5, the following steps are also included: Step S51: Annealing treatment: firstly, the injection molded particles are annealed at a temperature of 50-55° C. for 2-4 hours; Step S52: Secondary processing: Then, hot pressing treatment is performed at 220-230°C and 5-10 MPa for 0.5-3 hours.

[0010] Preferably, in step S6, the following steps are also included: Step S61: Determine the tensile properties according to GB / T1040 "Determination of tensile properties of plastics", determine the bending properties according to GB / T9341 "Determination of bending properties of plastics", and determine the impact properties according to GB / T1843 "Determination of cantilever beam impact strength of plastics"; Step S62: Determine the heat deformation temperature according to GB / T1634.2-2019 "Determination of Deformation Temperature of Plastics under Load", determine the glass transition temperature using ASTM E1356 standard of DSC, determine the shrinkage according to GB / T15585 "Determination of Shrinkage of Thermoplastic Plastic Injection Molding", and determine the melt flow rate according to GB / T3682.1-2018 "Determination of Melt Mass Flow Rate MFR and Melt Volume Flow Rate MVR of Thermoplastic Plastics".

[0011] Preferably, the composite filler is prepared by mixing mica powder, chitosan, nano-silica and hollow glass microspheres in a mass ratio of (1-3): (2-8): 1:0.5, the particle size range of the hollow glass microspheres is 6-8 mm, and the mica is one or more of muscovite, phlogopite, biotite, lepidolite and sericite, and its particle size range is 10-50 μm.

[0012] Preferably, the composite toughening agent is prepared by physically mixing NBR, SBR and EVA in a mass ratio of 3: (3.5-4): 4, and the composite compatibilizer is prepared by mixing SEBS, SMA, epoxy resin and maleic anhydride in a mass ratio of (40-60): (20-25): 20: 9.

[0013] Preferably, the surfactant solution is formed by mixing a surfactant, ethanol and water in a mass ratio of (0.1-5):45:55, and the surfactant is one of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, sodium dodecylbenzene sulfonate and sodium lauryl sulfate.

[0014] Preferably, the low shrinkage elastomer is one of TPE, TPU and POE, and the intrinsic viscosity of the PBT is 1 dL / g at room temperature.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention adopts a combined method of plasma treatment and surfactant coating to pretreat the toughening agent. First, plasma treatment is performed to introduce polar functional groups on the surface of the toughening agent through the interaction between high-energy particles and the surface of the toughening agent, thereby increasing the surface roughness and active sites. Then, surfactant coating is performed. The amphiphilic structure of the surfactant is utilized to make one end of the surfactant adsorb on the surface of the toughening agent, while the other end changes the interaction mode between the toughening agent and the PBT material. The combination of the two improves the compatibility of the toughening agent and the PBT material from different angles, thereby improving the shrinkage and toughness of the final prepared product.

[0016] 2. The present invention uses a composite toughening agent to synergistically improve the toughness of the PBT material and reduce the shrinkage of the PBT material. In addition, through a post-processing process, the compatibility between the toughening agent and PBT is improved during annealing, and then secondary processing is performed to make the interface between PBT and the toughening agent more tightly bonded, further improving the compatibility, while also improving the internal structure of the material and improving the comprehensive performance of the material.

[0017] 3. The present invention uses environmentally friendly composite fillers to fill and modify the PBT material, thereby improving the rigidity, hardness and tensile strength of the PBT material while increasing the toughness and impact resistance of the PBT material. The use of fillers can reduce the production cost of the PBT material, which helps to improve the surface properties of the PBT material to a certain extent, making the product surface smoother and more glossy, thereby improving the appearance quality of the PBT material product.

[0018] 4. The present invention combines a composite compatibilizer with a surface treatment technology to synergistically improve the compatibility between the elastomer and PBT, which helps to reduce the phase separation phenomenon, thereby improving the overall performance of the PBT material. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention are described clearly and completely. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0020] The present invention provides a low shrinkage elastomer toughened PBT material, and a preparation method of the low shrinkage elastomer toughened PBT material is as follows: Step S1: Raw material preparation: First, pre-treat the toughening agent, put the composite toughening agent into the reaction chamber of the plasma treatment equipment, introduce oxygen at a flow rate of 60sccm, and treat it at a power of 300W for 8min. Through the interaction between high-energy particles and the surface of the composite toughening agent, polar functional groups are introduced on the surface to increase active sites. Then, the composite toughening agent after plasma treatment is added to the surfactant solution for coating. The amphiphilic structure of the surfactant adsorbs on the surface of the composite toughening agent at one end, and changes the phase of the subsequent composite toughening agent and the PBT material at the other end. The mixture was stirred at 25 °C and 300 rpm for 4 hours, wherein the volume ratio of the surfactant solution to the composite toughening agent was 4:100, and then filtered, washed with deionized water, and dried in a vacuum oven at 60 °C for 5 hours. Then, the PBT was treated by placing the PBT resin in a blast drying oven at 150 °C for 2.5 hours, and then screening the PBT using a vibrating screen with a 90-mesh screen. Then, the pretreated PBT, composite fillers, lubricants and antioxidants were mixed according to The ratio of (50-60): (20-30): 0.2: 0.1 was added into the hopper of the twin-screw extruder, and the mixture was mixed for 20 minutes at a screw speed of 300 rpm and a temperature of 230°C. The low shrinkage elastomer was then dried in a vacuum drying oven at a drying temperature of 70°C and a drying time of 6 hours. The low shrinkage elastomer was then crushed in a pulverizer at a speed of 240 rpm and a crushing time of 40 minutes. The low shrinkage elastomer was then sieved with a screening device to screen out particles with a particle size of 80 μm. The composite toughening agent is composed of NBR, SBR and EVA. The material is prepared by physical mixing in a mass ratio of 3:3.5:4. The surfactant solution is prepared by mixing surfactant, ethanol and water in a mass ratio of 3:45:55. The intrinsic viscosity of PBT is 1 dL / g at room temperature. This viscous PBT is provided by Taiwan Changchun Company. The composite filler is prepared by mixing mica powder, chitosan, nano-silica and hollow glass microspheres in a mass ratio of (1-3): (2-8): 1:0.5. The particle size range of the hollow glass microspheres is 8 mm, and the particle size range of the mica is 30 μm. Step S2: Premix preparation: first, PBT, low shrinkage elastomer, composite toughening agent, composite compatibilizer and lubricant are added to a high-speed mixer, and stirred and mixed at a speed of 1000 rpm for 20 minutes to obtain a primary mixture, and then a UV stabilizer is added to the high-speed mixer, and stirred at a speed of 800 rpm for 10 minutes to obtain a premix, wherein the composite compatibilizer is prepared by mixing SEBS, SMA, epoxy resin and maleic anhydride in a mass ratio of 50:20:20:9, and the mass ratio of the pretreated PBT, low shrinkage elastomer, composite toughening agent and composite compatibilizer, lubricant and UV stabilizer is (60-70): (15-25): (4-8): (8-9): 1:0.5; Step S3: extrusion granulation: the premix is ​​fed into a twin-screw extruder, and blended at a speed of 120 rpm for 3 min at a temperature of 30° C., then the temperature is raised to 240° C. and blended at a speed of 380 rpm for 5 min, and then the extruded particles are cooled by water cooling, wherein the water temperature is 20° C. and the water flow rate is 1 m / s for 30 min, and then the particles are fed into a hot air drying oven and dried at a temperature of 40° C. for 30 min; Step S4: injection molding: adding the low shrinkage elastomer toughened PBT material particles prepared in step S3 into an injection molding machine for injection molding, wherein the mold temperature is 60° C., the injection pressure is 70 MPa, the holding pressure is 30 MPa, the injection speed is 60 mm / s, the mold opening speed is 30 mm / s, and the mold closing speed is 20 mm / s; Step S5: Post-treatment: The injection molded particles are first annealed at 50°C for 3.5 hours, and then hot-pressed at 220°C and 10 MPa for 1.5 hours.

[0021] Further, the value in step S1-2 is changed, and step S3-5 is performed, and the performance of the prepared low shrinkage elastomer toughened PBT material is tested.

[0022] Embodiment 1: Step S1: Raw material preparation: First, pre-treat the toughening agent, put the composite toughening agent into the reaction chamber of the plasma treatment equipment, introduce oxygen at a flow rate of 60sccm, and treat it at a power of 300W for 8min. Through the interaction between high-energy particles and the surface of the composite toughening agent, polar functional groups are introduced on the surface to increase active sites. Then, the composite toughening agent after plasma treatment is added to the surfactant solution for coating. The amphiphilic structure of the surfactant adsorbs on the surface of the composite toughening agent at one end, and changes the subsequent composite toughening at the other end. The interaction between the agent and the PBT material was studied. The surfactant solution was stirred for 4 hours at 25°C and 300 rpm, wherein the volume ratio of the surfactant solution to the composite toughening agent was 4:100. The surfactant solution was then filtered and washed with deionized water. The PBT was placed in a vacuum oven and dried at 60°C for 5 hours. The PBT was then treated by placing the PBT resin in a blast drying oven at 150°C for 2.5 hours. The PBT was then screened using a vibrating screen with a 90-mesh screen. PBT, composite filler, lubricant and antioxidant were added into the hopper of the twin-screw extruder in a ratio of 52:25:0.2:0.1, mixed for 20 min at a screw speed of 300 rpm and a temperature of 230°C, and then dried in a vacuum drying oven at a drying temperature of 70°C and a drying time of 6 h. The low shrinkage elastomer was then crushed in a pulverizer at a speed of 240 rpm and a crushing time of 40 min. It was then sieved with a screening device to screen out particles with a size of 80 μm, of which The composite toughening agent is prepared by physically mixing NBR, SBR and EVA in a mass ratio of 3:3.5:4, the surfactant solution is prepared by mixing a surfactant, ethanol and water in a mass ratio of 3:45:55, the intrinsic viscosity of PBT is 1dL / g at room temperature, and the composite filler is prepared by mixing mica powder, chitosan, nano-silica and hollow glass microspheres in a mass ratio of 3:7:1:0.5, the particle size range of the hollow glass microspheres is 8mm, and the particle size range of the mica is 30μm; Step S2: Preparation of premix: first add PBT, low shrinkage elastomer, composite toughening agent, composite compatibilizer and lubricant into a high-speed mixer, stir and mix at a speed of 1000 rpm for 20 minutes to obtain a primary mixture, then add the UV stabilizer into the high-speed mixer, and continue stirring at a speed of 800 rpm for 10 minutes to obtain a premix, wherein the composite compatibilizer is prepared by mixing SEBS, SMA, epoxy resin and maleic anhydride in a mass ratio of 50:20:20:9, and the mass ratio of the pretreated PBT, low shrinkage elastomer, composite toughening agent and composite compatibilizer, lubricant and UV stabilizer is 62:16:5:8:1:0.5.

[0023] Further, the tensile strength was measured to be 64.8MPa, the flexural strength was 77.9MPa, the impact strength was 86kJ / m², the heat deformation temperature was 154°C, the glass transition temperature was 27.5°C, the shrinkage at 23°C was 0.28%, and the melt flow rate was 12.9g / 10min.

[0024] Embodiment 2: Step S1: Raw material preparation: First, pre-treat the toughening agent, put the composite toughening agent into the reaction chamber of the plasma treatment equipment, introduce oxygen at a flow rate of 60sccm, and treat it at a power of 300W for 8min. Through the interaction between high-energy particles and the surface of the composite toughening agent, polar functional groups are introduced on the surface to increase active sites. Then, the composite toughening agent after plasma treatment is added to the surfactant solution for coating. The amphiphilic structure of the surfactant adsorbs on the surface of the composite toughening agent at one end, and changes the subsequent composite toughening at the other end. The interaction between the agent and the PBT material was studied. The surfactant solution was stirred for 4 hours at 25°C and 300 rpm, wherein the volume ratio of the surfactant solution to the composite toughening agent was 4:100. The surfactant solution was then filtered and washed with deionized water. The PBT was placed in a vacuum oven and dried at 60°C for 5 hours. The PBT was then treated by placing the PBT resin in a blast drying oven at 150°C for 2.5 hours. The PBT was then screened using a vibrating screen with a 90-mesh screen. PBT, composite filler, lubricant and antioxidant were added into the hopper of the twin-screw extruder in a ratio of 52:27:0.2:0.1, mixed for 20 min at a screw speed of 300 rpm and a temperature of 230°C, and then dried in a vacuum drying oven at a drying temperature of 70°C and a drying time of 6 h. The low shrinkage elastomer was then crushed in a pulverizer at a speed of 240 rpm and a crushing time of 40 min. It was then sieved with a screening device to screen out particles with a size of 80 μm, of which The composite toughening agent is prepared by physically mixing NBR, SBR and EVA in a mass ratio of 3:3.5:4, the surfactant solution is prepared by mixing a surfactant, ethanol and water in a mass ratio of 3:45:55, the intrinsic viscosity of PBT is 1dL / g at room temperature, and the composite filler is prepared by mixing mica powder, chitosan, nano-silica and hollow glass microspheres in a mass ratio of 3:6:1:0.5, the particle size range of the hollow glass microspheres is 8mm, and the particle size range of the mica is 30μm; Step S2: Preparation of premix: first add PBT, low shrinkage elastomer, composite toughening agent, composite compatibilizer and lubricant into a high-speed mixer, stir and mix at a speed of 1000 rpm for 20 minutes to obtain a primary mixture, then add the UV stabilizer into the high-speed mixer, and continue stirring at a speed of 800 rpm for 10 minutes to obtain a premix, wherein the composite compatibilizer is prepared by mixing SEBS, SMA, epoxy resin and maleic anhydride in a mass ratio of 50:20:20:9, and the mass ratio of the pretreated PBT, low shrinkage elastomer, composite toughening agent and composite compatibilizer, lubricant and UV stabilizer is 65:16:5:8:1:0.5.

[0025] Further, the tensile strength was measured to be 68.5MPa, the flexural strength was 81.2MPa, the impact strength was 89kJ / m², the heat deformation temperature was 158°C, the glass transition temperature was 26.1°C, the shrinkage at 23°C was 0.26%, and the melt flow rate was 13.4g / 10min.

[0026] Embodiment three: Step S1: Raw material preparation: First, pre-treat the toughening agent, put the composite toughening agent into the reaction chamber of the plasma treatment equipment, introduce oxygen at a flow rate of 60sccm, and treat it at a power of 300W for 8min. Through the interaction between high-energy particles and the surface of the composite toughening agent, polar functional groups are introduced on the surface to increase active sites. Then, the composite toughening agent after plasma treatment is added to the surfactant solution for coating. The amphiphilic structure of the surfactant adsorbs on the surface of the composite toughening agent at one end, and changes the subsequent composite toughening at the other end. The interaction between the agent and the PBT material was studied. The surfactant solution was stirred for 4 hours at 25°C and 300 rpm, wherein the volume ratio of the surfactant solution to the composite toughening agent was 4:100. The surfactant solution was then filtered and washed with deionized water. The PBT was placed in a vacuum oven and dried at 60°C for 5 hours. The PBT was then treated by placing the PBT resin in a blast drying oven at 150°C for 2.5 hours. The PBT was then screened using a vibrating screen with a 90-mesh screen. PBT, composite filler, lubricant and antioxidant were added into the hopper of the twin-screw extruder in a ratio of 55:27:0.2:0.1, mixed for 20 min at a screw speed of 300 rpm and a temperature of 230°C, and then dried in a vacuum drying oven at a drying temperature of 70°C and a drying time of 6 h. The low shrinkage elastomer was then crushed in a pulverizer at a speed of 240 rpm and a crushing time of 40 min. It was then sieved with a screening device to screen out particles with a size of 80 μm, of which The composite toughening agent is prepared by physically mixing NBR, SBR and EVA in a mass ratio of 3:3.5:4, the surfactant solution is prepared by mixing a surfactant, ethanol and water in a mass ratio of 3:45:55, the intrinsic viscosity of PBT is 1dL / g at room temperature, and the composite filler is prepared by mixing mica powder, chitosan, nano-silica and hollow glass microspheres in a mass ratio of 3:5:1:0.5, the particle size range of the hollow glass microspheres is 8mm, and the particle size range of the mica is 30μm; Step S2: Preparation of premix: first add PBT, low shrinkage elastomer, composite toughening agent, composite compatibilizer and lubricant into a high-speed mixer, stir and mix at a speed of 1000 rpm for 20 minutes to obtain a primary mixture, then add the UV stabilizer into the high-speed mixer, and continue stirring at a speed of 800 rpm for 10 minutes to obtain a premix, wherein the composite compatibilizer is prepared by mixing SEBS, SMA, epoxy resin and maleic anhydride in a mass ratio of 50:20:20:9, and the mass ratio of the pretreated PBT, low shrinkage elastomer, composite toughening agent and composite compatibilizer, lubricant and UV stabilizer is 65:20:5:8:1:0.5.

[0027] Further, the tensile strength was measured to be 69.8MPa, the flexural strength was 87.6MPa, the impact strength was 93kJ / m², the heat deformation temperature was 168°C, the glass transition temperature was 23.4°C, the shrinkage at 23°C was 0.21%, and the melt flow rate was 14.1g / 10min.

[0028] Embodiment 4: Step S1: Raw material preparation: First, pre-treat the toughening agent, put the composite toughening agent into the reaction chamber of the plasma treatment equipment, introduce oxygen at a flow rate of 60sccm, and treat it at a power of 300W for 8min. Through the interaction between high-energy particles and the surface of the composite toughening agent, polar functional groups are introduced on the surface to increase active sites. Then, the composite toughening agent after plasma treatment is added to the surfactant solution for coating. The amphiphilic structure of the surfactant adsorbs on the surface of the composite toughening agent at one end, and changes the subsequent composite toughening at the other end. The interaction between the agent and the PBT material was studied. The surfactant solution was stirred for 4 hours at 25°C and 300 rpm, wherein the volume ratio of the surfactant solution to the composite toughening agent was 4:100. The surfactant solution was then filtered and washed with deionized water. The PBT was placed in a vacuum oven and dried at 60°C for 5 hours. The PBT was then treated by placing the PBT resin in a blast drying oven at 150°C for 2.5 hours. The PBT was then screened using a vibrating screen with a 90-mesh screen. PBT, composite filler, lubricant and antioxidant were added into the hopper of the twin-screw extruder in a ratio of 57:27:0.2:0.1, mixed for 20 min at a screw speed of 300 rpm and a temperature of 230°C, and then dried in a vacuum drying oven at a drying temperature of 70°C and a drying time of 6 h. The low shrinkage elastomer was then crushed in a pulverizer at a speed of 240 rpm and a crushing time of 40 min. It was then sieved with a screening device to screen out particles with a size of 80 μm, of which The composite toughening agent is prepared by physically mixing NBR, SBR and EVA in a mass ratio of 3:3.5:4, the surfactant solution is prepared by mixing a surfactant, ethanol and water in a mass ratio of 3:45:55, the intrinsic viscosity of PBT is 1dL / g at room temperature, and the composite filler is prepared by mixing mica powder, chitosan, nano-silica and hollow glass microspheres in a mass ratio of 3:4:1:0.5, the particle size range of the hollow glass microspheres is 8mm, and the particle size range of the mica is 30μm; Step S2: Preparation of premix: first add PBT, low shrinkage elastomer, composite toughening agent, composite compatibilizer and lubricant into a high-speed mixer, stir and mix at a speed of 1000 rpm for 20 minutes to obtain a primary mixture, then add the UV stabilizer into the high-speed mixer, and continue stirring at a speed of 800 rpm for 10 minutes to obtain a premix, wherein the composite compatibilizer is prepared by mixing SEBS, SMA, epoxy resin and maleic anhydride in a mass ratio of 50:20:20:9, and the mass ratio of the pretreated PBT, low shrinkage elastomer, composite toughening agent and composite compatibilizer, lubricant and UV stabilizer is 65:22:5:8:1:0.5.

[0029] Further, the tensile strength was measured to be 68.2MPa, the flexural strength was 82.1MPa, the impact strength was 89kJ / m², the heat deformation temperature was 159°C, the glass transition temperature was 25.8°C, the shrinkage at 23°C was 0.23%, and the melt flow rate was 13.8g / 10min.

[0030] Embodiment five: Step S1: Raw material preparation: First, pre-treat the toughening agent, put the composite toughening agent into the reaction chamber of the plasma treatment equipment, introduce oxygen at a flow rate of 60sccm, and treat it at a power of 300W for 8min. Through the interaction between high-energy particles and the surface of the composite toughening agent, polar functional groups are introduced on the surface to increase active sites. Then, the composite toughening agent after plasma treatment is added to the surfactant solution for coating. The amphiphilic structure of the surfactant adsorbs on the surface of the composite toughening agent at one end, and changes the subsequent composite toughening at the other end. The interaction between the agent and the PBT material was studied. The surfactant solution was stirred for 4 hours at 25°C and 300 rpm, wherein the volume ratio of the surfactant solution to the composite toughening agent was 4:100. The surfactant solution was then filtered and washed with deionized water. The PBT was placed in a vacuum oven and dried at 60°C for 5 hours. The PBT was then treated by placing the PBT resin in a blast drying oven at 150°C for 2.5 hours. The PBT was then screened using a vibrating screen with a 90-mesh screen. PBT, composite filler, lubricant and antioxidant were added into the hopper of the twin-screw extruder in a ratio of 52:27:0.2:0.1, mixed for 20 min at a screw speed of 300 rpm and a temperature of 230°C, and then dried in a vacuum drying oven at a drying temperature of 70°C and a drying time of 6 h. The low shrinkage elastomer was then crushed in a pulverizer at a speed of 240 rpm and a crushing time of 40 min. It was then sieved with a screening device to screen out particles with a size of 80 μm, of which The composite toughening agent is prepared by physically mixing NBR, SBR and EVA in a mass ratio of 3:3.5:4, the surfactant solution is prepared by mixing a surfactant, ethanol and water in a mass ratio of 3:45:55, the intrinsic viscosity of PBT is 1dL / g at room temperature, and the composite filler is prepared by mixing mica powder, chitosan, nano-silica and hollow glass microspheres in a mass ratio of 2:5:1:0.5, the particle size range of the hollow glass microspheres is 8mm, and the particle size range of the mica is 30μm; Step S2: Preparation of premix: first add PBT, low shrinkage elastomer, composite toughening agent, composite compatibilizer and lubricant into a high-speed mixer, stir and mix at a speed of 1000 rpm for 20 minutes to obtain a primary mixture, then add the UV stabilizer into the high-speed mixer, and continue stirring at a speed of 800 rpm for 10 minutes to obtain a premix, wherein the composite compatibilizer is prepared by mixing SEBS, SMA, epoxy resin and maleic anhydride in a mass ratio of 50:20:20:9, and the mass ratio of the pretreated PBT, low shrinkage elastomer, composite toughening agent and composite compatibilizer, lubricant and UV stabilizer is 62:20:5:8:1:0.5.

[0031] Further, the tensile strength was measured to be 65.1MPa, the flexural strength was 79.3MPa, the impact strength was 87kJ / m², the heat deformation temperature was 155°C, the glass transition temperature was 26.6°C, the shrinkage at 23°C was 0.25%, and the melt flow rate was 13.4g / 10min.

[0032] Comparative Example: The commonly used PBT materials on the market are used as a comparative example. The tensile strength is 58.6MPa, the flexural strength is 69.1MPa, the impact strength is 77kJ / m², the heat deformation temperature is 148℃, the glass transition temperature is 29.8℃, the shrinkage rate at 23℃ is 0.31%, and the melt flow rate is 11.8g / 10min.

[0033] The results of the performance test of a low shrinkage elastomer toughened PBT material are as follows: Example one two three Four five Comparative Example Tensile strength MPa 64.8 68.5 69.8 68.2 65.1 58.6 Bending strength MPa 77.9 81.2 87.6 82.1 79.3 69.1 Impact strength kJ / m² 86 89 93 89 87 77 Heat deformation temperature℃ 154 158 168 159 155 148 Glass transition temperature℃ 27.5 26.1 23.4 25.8 26.6 29.8 Shrinkage (%) 23℃ 0.28 0.26 0.21 0.23 0.25 0.31 Melt flow rate (g / 10min) 12.9 13.4 14.1 13.8 13.4 11.8 It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above and that the present invention can be implemented in other specific forms without departing from the spirit or essential features of the present invention. Therefore, the embodiments should be considered exemplary and non-restrictive in all respects, and the scope of the present invention is defined by the appended claims rather than the above description, and it is intended that all changes falling within the meaning and scope of the equivalent elements of the claims be included in the present invention.

Claims

1. A low shrinkage elastomer toughened PBT material, characterized in that: The preparation method of low shrinkage elastomer toughened PBT material comprises the following steps: Step S1: raw material preparation: pre-treating the composite toughening agent, low shrinkage elastomer and PBT respectively; Step S2: Premix preparation: the PBT, low shrinkage elastomer, composite toughening agent, composite compatibilizer, lubricant and UV stabilizer pretreated in step S1 are sequentially added into a high-speed mixer in a mass ratio of (60-70): (15-25): (4-8): (8-9): (0.5-1.5): (0.2-0.6) for premixing to obtain a premix; Step S3: extrusion granulation: the mixed premix is ​​extruded and granulated through a twin-screw extruder to obtain low shrinkage elastomer toughened PBT material particles; Step S4: injection molding: adding the low shrinkage elastomer toughened PBT material particles prepared in step S3 into an injection molding machine for injection molding, wherein the mold temperature is 50-60° C., the injection pressure is 60-80 MPa, the holding pressure is 20-40 MPa, the injection speed is 60 mm / s, the mold opening speed is 30 mm / s, and the mold closing speed is 20 mm / s; Step S5: post-processing: post-processing the injection molded low shrinkage elastomer toughened PBT material particles; Step S6: Performance test: Performing performance test on the prepared low shrinkage elastomer toughened PBT material; In step S1, the following steps are also included: Step S11: toughening agent pretreatment: the composite toughening agent is placed in the reaction chamber of the plasma treatment equipment, oxygen is introduced at a flow rate of 50-80sccm, and the treatment is carried out for 5-10min at a power of 200-300W. The high-energy particles interact with the surface of the composite toughening agent, polar functional groups are introduced on the surface, and active sites are increased. Then, the composite toughening agent after plasma treatment is added to the surfactant solution for coating. The amphiphilic structure of the surfactant adsorbs on the surface of the composite toughening agent at one end, and changes the subsequent interaction mode between the composite toughening agent and the PBT material at the other end. Stir for 2-6h at 20-30°C and a speed of 200-400rpm, wherein the volume ratio of the surfactant solution to the composite toughening agent is (2-5):100, and then filter it, then wash it with deionized water, and place it in a vacuum box at a temperature of 50-60°C for 3-6h.

2. The low shrinkage elastomer toughened PBT material according to claim 1, characterized in that: In step S1, the following steps are also included: Step S12: PBT pretreatment: placing the PBT resin in a forced air drying oven at 150-160° C. for 2-3 hours, and then screening the PBT using a vibrating screen with a 90-mesh screen; Step S13: PBT modification: adding the pretreated PBT, composite filler, lubricant and antioxidant into the hopper of a twin-screw extruder in a ratio of (50-60): (20-30): 0.2: 0.1, and mixing for 10-40 minutes at a screw speed of 240-340 rpm and a temperature of 220-240°C; Step S14: Pretreatment of low shrinkage elastomer: Use a vacuum drying oven to dry the low shrinkage elastomer, wherein the drying temperature is 70°C and the drying time is 5-6h. Then, use a grinder to crush the low shrinkage elastomer at a rotation speed of 200-300rpm and a crushing time of 30-60min. Then, use a screening device to screen out the particle size of 50-100μm.

3. The low shrinkage elastomer toughened PBT material according to claim 1, characterized in that: In step S2, the following steps are also included: Step S21: firstly add PBT, low shrinkage elastomer, composite toughening agent, composite compatibilizer and lubricant into a high-speed mixer, and stir and mix them at a speed of 800-1200 rpm for 5-30 minutes to obtain a primary mixture; Step S22: Then, add the ultraviolet stabilizer into the high-speed mixer, and continue stirring at a speed of 600-800 rpm for 2-15 minutes to obtain a premix.

4. The low shrinkage elastomer toughened PBT material according to claim 1, characterized in that: In step S3, the following steps are also included: Step S31: feeding the premix into a twin-screw extruder, blending at a speed of 120-140 rpm for 2-3 min at a temperature of 25-35° C., then raising the temperature to 240-250° C. and blending at a speed of 350-400 rpm for 2-10 min; Step S32: The particles extruded in step S31 are cooled by water cooling, wherein the water temperature is 10-20°C, the water flow rate is 1-1.5 m / s, and the treatment is carried out for 20-40 min. Then, the particles are sent to a hot air drying oven and dried at a temperature of 30-50°C for 10-40 min.

5. The low shrinkage elastomer toughened PBT material according to claim 1, characterized in that: In step S5, the following steps are also included: Step S51: Annealing treatment: firstly, the injection molded particles are annealed at a temperature of 50-55° C. for 2-4 hours; Step S52: Secondary processing: Then, hot pressing treatment is performed at 220-230°C and 5-10 MPa for 0.5-3 hours.

6. The low shrinkage elastomer toughened PBT material according to claim 1, characterized in that: In step S6, the following steps are also included: Step S61: Determine the tensile properties according to GB / T1040 "Determination of tensile properties of plastics", determine the bending properties according to GB / T9341 "Determination of bending properties of plastics", and determine the impact properties according to GB / T1843 "Determination of cantilever beam impact strength of plastics"; Step S62: Determine the heat deformation temperature according to GB / T1634.2-2019 "Determination of Deformation Temperature of Plastics under Load", determine the glass transition temperature using ASTM E1356 standard of DSC, determine the shrinkage according to GB / T15585 "Determination of Shrinkage of Thermoplastic Plastic Injection Molding", and determine the melt flow rate according to GB / T3682.1-2018 "Determination of Melt Mass Flow Rate MFR and Melt Volume Flow Rate MVR of Thermoplastic Plastics".

7. The low shrinkage elastomer toughened PBT material according to claim 1, characterized in that: The composite filler is prepared by mixing mica powder, chitosan, nano-silicon dioxide and hollow glass microspheres in a mass ratio of (1-3): (2-8): 1:0.5, the particle size of the hollow glass microspheres is in the range of 6-8 mm, and the mica is one or more of muscovite, phlogopite, biotite, lepidolite and sericite, and the particle size is in the range of 10-50 μm.

8. The low shrinkage elastomer toughened PBT material according to claim 1, characterized in that: The composite toughening agent is prepared by physically mixing NBR, SBR and EVA in a mass ratio of 3: (3.5-4): 4, and the composite compatibilizer is prepared by mixing SEBS, SMA, epoxy resin and maleic anhydride in a mass ratio of (40-60): (20-25): 20:

9.

9. The low shrinkage elastomer toughened PBT material according to claim 1, characterized in that: The surfactant solution is prepared by mixing a surfactant, ethanol and water in a mass ratio of (0.1-5):45:55, and the surfactant is one of fatty alcohol polyoxyethylene ether, alkylphenol polyoxyethylene ether, sodium dodecylbenzene sulfonate and sodium lauryl sulfate.

10. The low shrinkage elastomer toughened PBT material according to claim 1, characterized in that: The low shrinkage elastomer is one of TPE, TPU and POE, and the intrinsic viscosity of the PBT is 1 dL / g at room temperature.