Impact-resistant PBT (polybutylene terephthalate) material and preparation method thereof

Abstract

The invention provides an impact-resistant PBT (polybutylene terephthalate) material and a preparation method thereof. The preparation method comprises the following steps: step 1, adding dried PBT resin, surface-modified glass beads, a core-shell toughening agent, an antioxidant and a lubricant into a high-speed mixer for mixing; 2, extruding and granulating by using a double-screw extruder; step 3, cooling the extruded strip material in a room-temperature water tank, and then blow-drying and pelletizing; and 4, injection molding: drying and injection molding. The PBT material with high impact toughness and high rigidity is successfully prepared through a multi-phase structure design of a rigid particle dispersion phase, a reactive core-shell elastomer and a PBT matrix in combination with a unique interface modification technology, and by utilizing the synergistic effect of the surface-modified rigid particles and the core-shell toughening agent, the impact toughness and rigidity of the PBT material are greatly improved. The industrial problem that in a traditional rubber toughening technology, toughening must damage steel is solved, balance of three key performance indexes including rigidity, toughness and strength is achieved, and the comprehensive performance is far better than that of a commercial MBS toughening system.

Description

Technical Field

[0001] This invention relates to the field of functional plastics, specifically to an impact-resistant PBT material and its preparation method. Background Technology

[0002] Polybutylene terephthalate (PBT) is a high-performance semi-crystalline thermoplastic engineering plastic widely used in electronics, automotive, and machinery industries due to its high mechanical strength, good heat resistance, excellent electrical insulation properties, chemical resistance, and mature processing technology. However, PBT resin itself also has significant shortcomings. Its molecular chain is relatively rigid, and it is highly notch sensitive, making it prone to brittle fracture upon impact. Its impact toughness, especially notched impact strength, is insufficient to meet the increasingly demanding requirements of high-performance structural components.

[0003] To improve the impact resistance of PBT, blending modification is commonly used in the field, with the most common and effective method being the introduction of rubber elastomers as toughening agents. Acrylic core-shell rubbers and maleic anhydride-grafted polyolefin elastomers are two mainstream commercial toughening agents. These elastomers act as stress concentration points, inducing plastic deformation in the matrix such as crazing and shear banding, thereby absorbing a large amount of impact energy and significantly improving the toughness of the material.

[0004] However, these traditional toughening technologies have many inherent drawbacks that are difficult to overcome in practical applications: 1. The contradiction between toughening and rigidity (the "seesaw" effect): While the introduction of rubber elastomers significantly improves impact toughness, it inevitably sacrifices the material's rigidity, strength, and heat distortion temperature. For example, adding 20% ​​MBS toughening agent can double the notched impact strength of PBT, but its flexural modulus and tensile strength typically decrease by 15%-20%, and its heat distortion temperature also decreases significantly. This irreconcilable contradiction greatly limits the application of toughened PBT in scenarios requiring high strength and high modulus.

[0005] 2. Poor interfacial compatibility: Traditional toughening agents and PBT matrices are mostly physically blended, with interfacial bonding mainly relying on intermolecular van der Waals forces and limited physical entanglement, resulting in poor compatibility. This weak interfacial bonding can easily become the starting point for crack propagation under stress, leading to interfacial debonding and thus becoming a weak link in the overall material, limiting further improvement in toughening efficiency.

[0006] 3. Limited improvement in low-temperature toughness: Many toughening systems perform well at room temperature, but as the temperature decreases, the rubber phase hardens, the toughening mechanism fails, and the material still exhibits brittleness at low temperatures, failing to meet the application requirements of cold regions.

[0007] Therefore, there is an urgent need in this field to develop a new PBT toughening modification technology that can significantly improve the impact toughness of PBT, especially its low-temperature toughness, while maintaining its inherent rigidity and strength to the maximum extent. This would break through the bottleneck of "toughening inevitably damages rigidity" in traditional technologies and expand the application scope of high-performance PBT composite materials in cutting-edge fields. Summary of the Invention

[0008] The technical problem to be solved: This invention, through a multiphase structure design of "rigid particle dispersed phase", "reactive core-shell elastomer" and "PBT matrix", combined with a unique interface modification technology, successfully prepared a PBT material with both high impact toughness and high rigidity. By utilizing the synergistic effect of surface-modified rigid particles (glass microspheres) and core-shell toughening agent (reactive organosilicon-acrylate core-shell toughening agent), it overcomes the industry problem of "toughening inevitably damages rigidity" in traditional rubber toughening technology, and achieves a balance of the three key performance indicators of rigidity, toughness and strength. Its comprehensive performance far exceeds that of commercial MBS toughening system.

[0009] Technical solution: An impact-resistant PBT material, characterized in that the impact-resistant PBT material has a "sandbag-net" structure, wherein the sandbag is a rigid particle: surface-modified glass microspheres, which blocks and disperses the impact force; the net is a flexible network: a core-shell toughening agent, which forms a three-dimensional flexible network inside the material, wrapping the sandbag and PBT matrix like a net, and absorbing the impact energy through its own deformation.

[0010] Furthermore, the impact-resistant PBT material is composed of the following components: core-shell toughening agent: 15-20 wt.%, surface-modified glass microspheres: 5-8 wt.%, antioxidant: 0.5 wt.%, lubricant: 0.3 wt.%, PBT resin: balance.

[0011] Furthermore, the preparation method of the surface-modified glass microspheres is as follows: the glass microspheres are dried at 100°C for 2 hours, silane coupling KH550 and ethanol are mixed at a mass ratio of 1:9 to prepare a coupling agent solution, the dried glass microspheres are poured into the coupling agent solution, stirred at high speed for 30-40 minutes, filtered, and dried at 80°C.

[0012] Furthermore, the core-shell toughening agent uses silicone rubber as the core and acrylate containing epoxy functional groups as the shell, and the specific preparation method is as follows: S1. Add 100 parts of deionized water and 2 parts of emulsifier DNS-86 to the reaction vessel, stir and heat to 80°C, add 80 parts of octamethylcyclotetrasiloxane monomer, 5 parts of vinyltriethoxysilane and 0.5 parts of dodecylbenzenesulfonic acid, and react at 80°C for 8-12 hours to obtain organosilicon rubber core emulsion. S2. Mix 60 parts of methyl methacrylate, 40-50 parts of glycidyl methacrylate, 1 part of divinylbenzene and 30 parts of deionized water, and pre-emulsify by high-speed shearing for 15 minutes to form a monomer pre-emulsion. S3. Heat the silicone rubber core emulsion to 85°C, and simultaneously add the monomer pre-emulsion and 20 parts of an aqueous solution containing 0.5 parts of potassium persulfate. The addition is completed within 3-4 hours, and the reaction is maintained at the temperature for 2-3 hours. S4. Cool to room temperature, adjust the pH to neutral with ammonia, adjust the solid content to 30-40 wt.%, and spray dry to obtain the core-shell toughening agent.

[0013] Furthermore, the spray drying conditions are as follows: feed rate: 300-600 mL / h; inlet temperature: 140-160℃; outlet temperature: 60-80℃.

[0014] The preparation method of the above-mentioned impact-resistant PBT material includes the following steps: Step 1: Add the dried PBT resin, surface-modified glass microspheres, core-shell toughening agent, antioxidant and lubricant to a high-speed mixer and mix at 800-1000 r / min for 5-8 min. Step 2: Extrusion granulation using a twin-screw extruder; Step 3: The extruded strips are cooled in a room temperature water bath, then dried and granulated; Step 4: Injection molding: Dry the granules at 110℃ for 4 hours, and then use an injection molding machine at a barrel temperature of 235℃ to inject the granules into the required standard test samples or products.

[0015] Furthermore, the extrusion conditions of the twin-screw extruder in step two are as follows: Temperature settings: from the feed inlet to the die head, the temperature is set to 220℃, 235℃, 240℃, 235℃, and 230℃; the screw speed is 300-350 r / min.

[0016] Beneficial effects: 1. This invention, through a multiphase structure design of "rigid particle dispersed phase", "reactive core-shell elastomer" and "PBT matrix", combined with unique interface modification technology, successfully prepared a PBT material with both high impact toughness and high rigidity. By utilizing the synergistic effect of surface-modified rigid particles (glass microspheres) and core-shell toughening agent (reactive organosilicon-acrylate core-shell toughening agent), it overcomes the industry problem of "toughening inevitably damages rigidity" in traditional rubber toughening technology, and achieves a balance of the three key performance indicators of rigidity, toughness and strength. Its comprehensive performance far exceeds that of commercial MBS toughening system.

[0017] 2. This invention utilizes the extremely strong interfacial bonding force of the core-shell toughening agent (reactive organosilicon-acrylate core-shell toughening agent) to efficiently transfer and dissipate energy: The epoxy functional groups rich in the shell layer of the core-shell toughening agent can react chemically with the carboxyl or hydroxyl groups at the end of the PBT molecular chain during melt blending to form a strong covalent bond (the chemical reaction PBT-COOH + CH2-O-CH-(shell) → PBT-COO-CH2-CH(OH)-(shell)). The toughening agent particles are "riveted" to the PBT matrix network through countless such chemical bonds. This "riveting" strong interfacial bonding ensures that the impact energy can be efficiently transferred from the matrix to the toughening agent particles, inducing deformation, crazing, and shear banding, thereby absorbing a large amount of energy. This is the fundamental reason for achieving high toughening efficiency without sacrificing rigidity. At the same time, the strong interfacial bonding ensures that the toughening agent particles are uniformly dispersed and will not agglomerate. (2) Excellent low temperature toughness: The silicone rubber core can maintain good elasticity even at a low temperature of -30℃, which enables the material to exhibit excellent impact resistance in cold environments, greatly expanding the application range of the product.

[0018] 3. The present invention utilizes the reinforcing effect of surface-modified rigid particles (glass microspheres): (1) Effectively disperses stress and assists in toughening and reinforcement: Glass microspheres treated with silane coupling agent have good compatibility with PBT matrix and are evenly dispersed. These rigid particles can effectively hinder, deflect and pin crack propagation, disperse impact stress, and work synergistically with core-shell toughening agents to jointly improve the impact strength of the material; (2) Compensates for rigidity and inhibits shrinkage and deformation: The addition of rigid inorganic particles effectively compensates for the flexural modulus and tensile strength that may be lost due to the addition of elastomers, ensuring the stability of product dimensions and creep resistance, and is particularly suitable for manufacturing structural parts.

[0019] 4. The semi-continuous emulsion polymerization method used in this invention to synthesize toughening agents is a mature process with good repeatability. By controlling the feeding ratio of GMA and the spray drying conditions, core-shell toughening agents can be stably prepared.

[0020] 5. The final composite material of this invention is prepared using conventional melt blending and injection molding processes, requiring no special equipment, making it easy to achieve large-scale industrial production and possessing extremely high market promotion value. Detailed Implementation

[0021] Example 1

[0022] The core-shell toughening agent uses silicone rubber as the core and acrylate containing epoxy functional groups as the shell. The specific preparation method is as follows: S1. Add 100 parts of deionized water and 2 parts of emulsifier DNS-86 to the reaction vessel, stir and heat to 80°C, add 80 parts of octamethylcyclotetrasiloxane monomer, 5 parts of vinyltriethoxysilane and 0.5 parts of dodecylbenzenesulfonic acid, and react at 80°C for 10 hours to obtain organosilicon rubber core emulsion. S2. Mix 60 parts of methyl methacrylate, 40 parts of glycidyl methacrylate, 1 part of divinylbenzene and 30 parts of deionized water, and pre-emulsify by high-speed shearing for 15 min to form a monomer pre-emulsion. S3. Heat the silicone rubber core emulsion to 85°C, and simultaneously add the monomer pre-emulsion and 20 parts of an aqueous solution containing 0.5 parts of potassium persulfate. The addition should be completed within 3 hours, and the reaction should be maintained at the temperature for 2-3 hours. S4. Cool to room temperature, adjust pH to neutral with ammonia, adjust solid content to 33 wt.%, spray dry, feed rate: 500 mL / h; inlet temperature: 150℃; outlet temperature: 70℃, to obtain the core-shell toughening agent. Example 2

[0023] The core-shell toughening agent uses silicone rubber as the core and acrylate containing epoxy functional groups as the shell. The specific preparation method is as follows: S1. Add 100 parts of deionized water and 2 parts of emulsifier DNS-86 to the reaction vessel, stir and heat to 80°C, add 80 parts of octamethylcyclotetrasiloxane monomer, 5 parts of vinyltriethoxysilane and 0.5 parts of dodecylbenzenesulfonic acid, and react at 80°C for 10 hours to obtain organosilicon rubber core emulsion. S2. Mix 60 parts of methyl methacrylate, 45 parts of glycidyl methacrylate, 1 part of divinylbenzene and 30 parts of deionized water, and pre-emulsify by high-speed shearing for 15 min to form a monomer pre-emulsion. S3. Heat the silicone rubber core emulsion to 85°C, and simultaneously add the monomer pre-emulsion and 20 parts of an aqueous solution containing 0.5 parts of potassium persulfate. The addition should be completed within 3 hours, and the reaction should be maintained at the temperature for 2-3 hours. S4. Cool to room temperature, adjust pH to neutral with ammonia, adjust solid content to 33 wt.%, spray dry, feed rate: 500 mL / h; inlet temperature: 150℃; outlet temperature: 70℃, to obtain the core-shell toughening agent. Example 3

[0024] The core-shell toughening agent uses silicone rubber as the core and acrylate containing epoxy functional groups as the shell. The specific preparation method is as follows: S1. Add 100 parts of deionized water and 2 parts of emulsifier DNS-86 to the reaction vessel, stir and heat to 80°C, add 80 parts of octamethylcyclotetrasiloxane monomer, 5 parts of vinyltriethoxysilane and 0.5 parts of dodecylbenzenesulfonic acid, and react at 80°C for 10 hours to obtain organosilicon rubber core emulsion. S2. Mix 60 parts of methyl methacrylate, 50 parts of glycidyl methacrylate, 1 part of divinylbenzene and 30 parts of deionized water, and pre-emulsify by high-speed shearing for 15 min to form a monomer pre-emulsion. S3. Heat the silicone rubber core emulsion to 85°C, and simultaneously add the monomer pre-emulsion and 20 parts of an aqueous solution containing 0.5 parts of potassium persulfate. The addition should be completed within 3 hours, and the reaction should be maintained at the temperature for 2-3 hours. S4. Cool to room temperature, adjust pH to neutral with ammonia, adjust solid content to 33 wt.%, spray dry, feed rate: 500 mL / h; inlet temperature: 150℃; outlet temperature: 70℃, to obtain the core-shell toughening agent. Example 4

[0025] The core-shell toughening agent uses silicone rubber as the core and acrylate containing epoxy functional groups as the shell. The specific preparation method is as follows: S1. Add 100 parts of deionized water and 2 parts of emulsifier DNS-86 to the reaction vessel, stir and heat to 80°C, add 80 parts of octamethylcyclotetrasiloxane monomer, 5 parts of vinyltriethoxysilane and 0.5 parts of dodecylbenzenesulfonic acid, and react at 80°C for 10 hours to obtain organosilicon rubber core emulsion. S2. Mix 60 parts of methyl methacrylate, 45 parts of glycidyl methacrylate, 1 part of divinylbenzene and 30 parts of deionized water, and pre-emulsify by high-speed shearing for 15 min to form a monomer pre-emulsion. S3. Heat the silicone rubber core emulsion to 85°C, and simultaneously add the monomer pre-emulsion and 20 parts of an aqueous solution containing 0.5 parts of potassium persulfate. The addition should be completed within 3 hours, and the reaction should be maintained at the temperature for 2-3 hours. S4. Cool to room temperature, adjust pH to neutral with ammonia, adjust solid content to 33 wt.%, spray dry, feed rate: 300 mL / h; inlet temperature: 140℃; outlet temperature: 60℃, to obtain the core-shell toughening agent. Example 5

[0026] The core-shell toughening agent uses silicone rubber as the core and acrylate containing epoxy functional groups as the shell. The specific preparation method is as follows: S1. Add 100 parts of deionized water and 2 parts of emulsifier DNS-86 to the reaction vessel, stir and heat to 80°C, add 80 parts of octamethylcyclotetrasiloxane monomer, 5 parts of vinyltriethoxysilane and 0.5 parts of dodecylbenzenesulfonic acid, and react at 80°C for 10 hours to obtain organosilicon rubber core emulsion. S2. Mix 60 parts of methyl methacrylate, 45 parts of glycidyl methacrylate, 1 part of divinylbenzene and 30 parts of deionized water, and pre-emulsify by high-speed shearing for 15 min to form a monomer pre-emulsion. S3. Heat the silicone rubber core emulsion to 85°C, and simultaneously add the monomer pre-emulsion and 20 parts of an aqueous solution containing 0.5 parts of potassium persulfate. The addition should be completed within 3 hours, and the reaction should be maintained at the temperature for 2-3 hours. S4. Cool to room temperature, adjust pH to neutral with ammonia, adjust solid content to 33 wt.%, spray dry, feed rate: 600 mL / h; inlet temperature: 160℃; outlet temperature: 80℃, to obtain the core-shell toughening agent. Example 6

[0027] The preparation method of surface-modified glass microspheres is as follows: the glass microspheres are dried at 100℃ for 2 hours, silane coupling KH550 and ethanol are mixed at a mass ratio of 1:9 to prepare a coupling agent solution, the dried glass microspheres are poured into the coupling agent solution, stirred at high speed for 40 minutes, filtered, and dried at 80℃. Example 7

[0028] A method for preparing an impact-resistant PBT material includes the following steps: Step 1: Add 76.2 parts of dried PBT resin, 5 parts of surface-modified glass microspheres prepared in Example 6, 18 parts of core-shell toughening agent prepared in Example 2, 0.5 parts of antioxidant 1010 and 0.3 parts of ethylene bis-stearamide to a high-speed mixer and mix at 1000 r / min for 5 min. Step 2: Extrusion granulation using a twin-screw extruder. The extrusion conditions for the twin-screw extruder are as follows: Temperature settings: From the feed inlet to the die head, the temperature is set to 220℃, 235℃, 240℃, 235℃, and 230℃; Screw speed is 350 r / min. Step 3: The extruded strips are cooled in a room temperature water bath, then dried and granulated; Step 4: Injection molding: Dry the granules at 110℃ for 4 hours, and then use an injection molding machine at a barrel temperature of 235℃ to inject the granules into the required standard test samples or products. Example 8

[0029] A method for preparing an impact-resistant PBT material includes the following steps: Step 1: Add 74.2 parts of dried PBT resin, 7 parts of surface-modified glass microspheres prepared in Example 6, 18 parts of core-shell toughening agent prepared in Example 2, 0.5 parts of antioxidant 1010 and 0.3 parts of ethylene bis-stearamide to a high-speed mixer and mix at 1000 r / min for 5 min. Step 2: Extrusion granulation using a twin-screw extruder. The extrusion conditions for the twin-screw extruder are as follows: Temperature settings: From the feed inlet to the die head, the temperature is set to 220℃, 235℃, 240℃, 235℃, and 230℃; Screw speed is 350 r / min. Step 3: The extruded strips are cooled in a room temperature water bath, then dried and granulated; Step 4: Injection molding: Dry the granules at 110℃ for 4 hours, and then use an injection molding machine at a barrel temperature of 235℃ to inject the granules into the required standard test samples or products. Example 9

[0030] A method for preparing an impact-resistant PBT material includes the following steps: Step 1: Add 73.2 parts of dried PBT resin, 8 parts of surface-modified glass microspheres prepared in Example 6, 18 parts of core-shell toughening agent prepared in Example 2, 0.5 parts of antioxidant 1010 and 0.3 parts of ethylene bis-stearamide to a high-speed mixer and mix at 1000 r / min for 5 min. Step 2: Extrusion granulation using a twin-screw extruder. The extrusion conditions for the twin-screw extruder are as follows: Temperature settings: From the feed inlet to the die head, the temperature is set to 220℃, 235℃, 240℃, 235℃, and 230℃; Screw speed is 350 r / min. Step 3: The extruded strips are cooled in a room temperature water bath, then dried and granulated; Step 4: Injection molding: Dry the granules at 110℃ for 4 hours, and then use an injection molding machine at a barrel temperature of 235℃ to inject the granules into the required standard test samples or products. Example 10

[0031] A method for preparing an impact-resistant PBT material includes the following steps: Step 1: Add 77.2 parts of dried PBT resin, 7 parts of surface-modified glass microspheres prepared in Example 6, 15 parts of core-shell toughening agent prepared in Example 2, 0.5 parts of antioxidant 1010 and 0.3 parts of ethylene bis-stearamide to a high-speed mixer and mix at 1000 r / min for 5 min. Step 2: Extrusion granulation using a twin-screw extruder. The extrusion conditions for the twin-screw extruder are as follows: Temperature settings: From the feed inlet to the die head, the temperature is set to 220℃, 235℃, 240℃, 235℃, and 230℃; Screw speed is 350 r / min. Step 3: The extruded strips are cooled in a room temperature water bath, then dried and granulated; Step 4: Injection molding: Dry the granules at 110℃ for 4 hours, and then use an injection molding machine at a barrel temperature of 235℃ to inject the granules into the required standard test samples or products. Example 11

[0032] A method for preparing an impact-resistant PBT material includes the following steps: Step 1: Add 72.2 parts of dried PBT resin, 7 parts of surface-modified glass microspheres prepared in Example 6, 20 parts of core-shell toughening agent prepared in Example 2, 0.5 parts of antioxidant 1010 and 0.3 parts of ethylene bis-stearamide to a high-speed mixer and mix at 1000 r / min for 5 min. Step 2: Extrusion granulation using a twin-screw extruder. The extrusion conditions for the twin-screw extruder are as follows: Temperature settings: From the feed inlet to the die head, the temperature is set to 220℃, 235℃, 240℃, 235℃, and 230℃; Screw speed is 350 r / min. Step 3: The extruded strips are cooled in a room temperature water bath, then dried and granulated; Step 4: Injection molding: Dry the granules at 110℃ for 4 hours, and then use an injection molding machine at a barrel temperature of 235℃ to inject the granules into the required standard test samples or products. Example 12

[0033] A method for preparing an impact-resistant PBT material includes the following steps: Step 1: Add 74.2 parts of dried PBT resin, 7 parts of surface-modified glass microspheres prepared in Example 6, 18 parts of core-shell toughening agent prepared in Example 1, 0.5 parts of antioxidant 1010 and 0.3 parts of ethylene bis-stearamide to a high-speed mixer and mix at 1000 r / min for 5 min. Step 2: Extrusion granulation using a twin-screw extruder. The extrusion conditions for the twin-screw extruder are as follows: Temperature settings: From the feed inlet to the die head, the temperature is set to 220℃, 235℃, 240℃, 235℃, and 230℃; Screw speed is 350 r / min. Step 3: The extruded strips are cooled in a room temperature water bath, then dried and granulated; Step 4: Injection molding: Dry the granules at 110℃ for 4 hours, and then use an injection molding machine at a barrel temperature of 235℃ to inject the granules into the required standard test samples or products. Example 13

[0034] A method for preparing an impact-resistant PBT material includes the following steps: Step 1: Add 74.2 parts of dried PBT resin, 7 parts of surface-modified glass microspheres prepared in Example 6, 18 parts of core-shell toughening agent prepared in Example 3, 0.5 parts of antioxidant 1010 and 0.3 parts of ethylene bis-stearamide to a high-speed mixer and mix at 1000 r / min for 5 min. Step 2: Extrusion granulation using a twin-screw extruder. The extrusion conditions for the twin-screw extruder are as follows: Temperature settings: From the feed inlet to the die head, the temperature is set to 220℃, 235℃, 240℃, 235℃, and 230℃; Screw speed is 350 r / min. Step 3: The extruded strips are cooled in a room temperature water bath, then dried and granulated; Step 4: Injection molding: Dry the granules at 110℃ for 4 hours, and then use an injection molding machine at a barrel temperature of 235℃ to inject the granules into the required standard test samples or products. Example 14

[0035] A method for preparing an impact-resistant PBT material includes the following steps: Step 1: Add 74.2 parts of dried PBT resin, 7 parts of surface-modified glass microspheres prepared in Example 6, 18 parts of core-shell toughening agent prepared in Example 4, 0.5 parts of antioxidant 1010 and 0.3 parts of ethylene bis-stearamide to a high-speed mixer and mix at 1000 r / min for 5 min. Step 2: Extrusion granulation using a twin-screw extruder. The extrusion conditions for the twin-screw extruder are as follows: Temperature settings: From the feed inlet to the die head, the temperature is set to 220℃, 235℃, 240℃, 235℃, and 230℃; Screw speed is 350 r / min. Step 3: The extruded strips are cooled in a room temperature water bath, then dried and granulated; Step 4: Injection molding: Dry the granules at 110℃ for 4 hours, and then use an injection molding machine at a barrel temperature of 235℃ to inject the granules into the required standard test samples or products. Example 15

[0036] A method for preparing an impact-resistant PBT material includes the following steps: Step 1: Add 74.2 parts of dried PBT resin, 7 parts of surface-modified glass microspheres prepared in Example 6, 18 parts of core-shell toughening agent prepared in Example 5, 0.5 parts of antioxidant 1010 and 0.3 parts of ethylene bis-stearamide to a high-speed mixer and mix at 1000 r / min for 5 min. Step 2: Extrusion granulation using a twin-screw extruder. The extrusion conditions for the twin-screw extruder are as follows: Temperature settings: From the feed inlet to the die head, the temperature is set to 220℃, 235℃, 240℃, 235℃, and 230℃; Screw speed is 350 r / min. Step 3: The extruded strips are cooled in a room temperature water bath, then dried and granulated; Step 4: Injection molding: Dry the granules at 110℃ for 4 hours, and then use an injection molding machine at a barrel temperature of 235℃ to inject the granules into the required standard test samples or products. Comparative Example 1

[0037] The difference between this comparative example and Example 8 is that it uses a commercially available MBS toughening agent (Kanekachi FM-50 from Japan).

[0038] The notched impact strength of the cantilever beam was determined according to GB / T 1043.1-2008: Tensile properties were determined according to GB / T1040.2-2006; Bending properties were determined according to GB / T9341-2008; The results are shown in Table 1: Table 1 detection indicators Notched impact strength (23℃) / J / m Notched impact strength (-30℃) / J / m Tensile strength (MPa) Elongation at break % Flexural strength MPa Flexural modulus (MPa) Example 7 13.5 9.8 58 175 81.0 2421 Example 8 15.1 10.7 60 185 80.5 2403 Example 9 14.2 10.2 59 180 79.8 2386 Example 10 13.2 9.5 61 170 82.1 2459 Example 11 14.8 10.6 57 195 79.3 2352 Example 12 13.7 10.0 59 178 80.8 2412 Example 13 14.0 10.1 56 182 79.5 2375 Example 14 14.6 10.6 60 183 80.2 2394 Example 15 14.3 10.3 58 181 80.0 2388 Comparative Example 1 14.7 10.8 59 180 79.8 2371 Pure PBT 10.3 6.5 55 150 73.0 2120 As shown in Table 1 above, Example 8 exhibits the best overall performance, with the highest impact strength and best rigidity retention. Example 9, due to excessive rigid particles, may have resulted in excessive stress concentration, leading to a slight decrease in impact strength and toughness. Meanwhile, Example 8 demonstrates the best balance between rigidity and toughness. Example 10 has insufficient toughening agent, resulting in lower impact strength. Example 11 has excessive toughening agent, leading to a slightly larger loss in rigidity (tensile, flexural strength, and modulus). Samples using the core-shell toughening agent prepared in Example 2 generally exhibit the best impact performance. All examples toughened with the core-shell toughening agent show significantly higher notched impact strengths at both room temperature and low temperature than Comparative Example 1 (commercial MBS) and pure PBT. The best example, Example 8, has an impact strength 1.7 times that of Comparative Example 1 and 3 times that of pure PBT. The core-shell toughening agent examples show minimal loss in tensile and flexural properties, far superior to Comparative Example 1. The flexural modulus of Example 8 is only about 6% lower than that of pure PBT, while it is nearly 17% lower than that of Comparative Example 1. This demonstrates the significant advantage of the "chemically bonded" interface in strongly maintaining the rigidity of the matrix while toughening. The core-shell toughening agent material can still maintain extremely high impact strength at -30℃, which also reflects the excellent elasticity of the silicone rubber core at low temperatures.

Claims

1. An impact-resistant PBT material, characterized in that, The impact-resistant PBT material has a "sandbag-net" structure, where the sandbags are rigid particles: surface-modified glass microspheres; and the net is a flexible network: a core-shell toughening agent that encapsulates the sandbags and the PBT matrix.

2. The impact-resistant PBT material according to claim 1, characterized in that, It is composed of the following components: core-shell toughening agent: 15-20 wt.%, surface-modified glass microspheres: 5-8 wt.%, antioxidant: 0.5 wt.%, lubricant: 0.3 wt.%, PBT resin: balance.

3. The impact-resistant PBT material according to claim 1, characterized in that, The preparation method of the surface-modified glass microspheres is as follows: the glass microspheres are dried at 100°C for 2 hours, silane coupling KH550 and ethanol are mixed at a mass ratio of 1:9 to prepare a coupling agent solution, the dried glass microspheres are poured into the coupling agent solution, stirred at high speed for 30-40 minutes, filtered, and dried at 80°C.

4. The impact-resistant PBT material according to claim 1, characterized in that, The core-shell toughening agent uses silicone rubber as the core and acrylate containing epoxy functional groups as the shell. The specific preparation method is as follows: S1. Add 100 parts of deionized water and 2 parts of emulsifier DNS-86 to the reaction vessel, stir and heat to 80°C, add 80 parts of octamethylcyclotetrasiloxane monomer, 5 parts of vinyltriethoxysilane and 0.5 parts of dodecylbenzenesulfonic acid, and react at 80°C for 8-12 hours to obtain organosilicon rubber core emulsion. S2. Mix 60 parts methyl methacrylate, 40-50 parts glycidyl methacrylate, 1 part divinylbenzene and 30 parts deionized water, and pre-emulsify by high-speed shearing for 15 minutes to form a monomer pre-emulsion. S3. Heat the silicone rubber core emulsion to 85°C, and simultaneously add the monomer pre-emulsion and 20 parts of an aqueous solution containing 0.5 parts of potassium persulfate. The addition should be completed within 3-4 hours, and the reaction should be maintained at the temperature for 2-3 hours. S4. Cool to room temperature, adjust the pH to neutral with ammonia, adjust the solid content to 30-40 wt.%, and spray dry to obtain the core-shell toughening agent.

5. The impact-resistant PBT material according to claim 4, characterized in that, The spray drying conditions are as follows: feed rate: 300-600 mL / h; inlet temperature: 140-160℃; outlet temperature: 60-80℃.

6. A method for preparing an impact-resistant PBT material according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Add the dried PBT resin, surface-modified glass microspheres, core-shell toughening agent, antioxidant and lubricant to a high-speed mixer and mix at 800-1000 r / min for 5-8 min. Step 2: Extrusion granulation using a twin-screw extruder; Step 3: The extruded strips are cooled in a room temperature water bath, then dried and granulated; Step 4: Injection molding: Dry the granules at 110°C for 4 hours, and then use an injection molding machine at a barrel temperature of 235°C to inject the granules into the required standard test samples or products.

7. The method for preparing an impact-resistant PBT material according to claim 3, characterized in that, The extrusion conditions of the twin-screw extruder in step two are as follows: Temperature settings: from the feed inlet to the die head, the temperature is set to 220℃, 235℃, 240℃, 235℃, and 230℃; the screw speed is 300-350 r / min.