A pc / pbt modified plastic and a preparation method thereof

Abstract

The application discloses a PC / PBT modified plastic and a preparation method thereof in the technical field of modified plastics, and comprises the following components in parts by weight: polycarbonate (PC) 70-80 parts, maleic anhydride modified polybutylene terephthalate (maleic anhydride modified PBT) 20-30 parts and reinforcing agent 15-20 parts. The application provides high strength and thermal stability through PC, improves the rigidity and dimensional stability of the material through PBT, disperses the reinforcing agent in the phase interface to form a "soft phase toughening" area, absorbs impact energy, prevents crack propagation, forms a chemical bond crosslinking structure through multiple reaction sites, and further improves the impact performance and heat resistance.

Description

Technical Field

[0001] This invention belongs to the field of modified plastics technology, specifically referring to a PC / PBT modified plastic and its preparation method. Background Technology

[0002] Polycarbonate (PC) and polybutylene terephthalate (PBT), as two important members of modern engineering plastics, are widely used in many fields such as electronics, automotive, home appliances, and information and communication equipment due to their excellent mechanical properties, thermal stability, electrical properties, and processing performance. However, single-variety resins still have certain limitations while meeting the comprehensive performance requirements of modern industrial products. Therefore, blending modification to complement the advantages of two or more polymer materials has become an important development direction for improving the comprehensive performance of engineering plastics. PC is an amorphous thermoplastic with excellent impact strength, transparency, dimensional stability, and good electrical insulation properties. The main disadvantages of PC are poor solvent resistance, limited chemical corrosion resistance, poor flowability, and high processing temperature. In addition, although PC has excellent toughness, its brittleness increases significantly at low temperatures, and there is a risk of stress cracking with long-term use. Polyester polymer (PBT) is a crystalline polyester material with excellent heat resistance, abrasion resistance, good dimensional stability, and processing flowability. It has a short molding cycle, making it suitable for high-speed injection molding, and is particularly suitable for manufacturing precision electronic components. However, PBT itself has relatively low impact resistance, is quite brittle, and is prone to hydrolysis in humid environments, affecting its mechanical strength. Blending PC (PC) with PBT combines the high toughness of PC with the high crystallinity and good flowability of PBT, producing a blend material with excellent overall performance. This PC / PBT blend possesses both the high strength and toughness of PC and the easy processing and chemical resistance of PBT, making it a widely used modified plastic system in the electronics, electrical, and automotive industries.

[0003] Although PC and PBT have strong complementarity, their blending process faces a series of technical challenges, mainly including the following: Compatibility issues: PC is an amorphous polymer, while PBT is a semi-crystalline polymer. Significant differences exist between them in molecular structure, polarity, and thermal properties. Direct blending easily leads to phase separation, resulting in poor interfacial bonding and decreased mechanical properties. Insufficient impact resistance: Under high or low temperature environments, the impact resistance of PC / PBT blends still fails to meet the requirements of some structural components, especially with low notched impact strength. The material is prone to crack propagation and brittle fracture upon impact. Processing stability issues: Improper addition of compatibilizers or other additives in the blend can cause thermal degradation, decomposition bubbles, and rough surface finish, affecting the molding quality and appearance of the finished product. Summary of the Invention

[0004] To address the above issues and overcome the shortcomings of existing technologies, this invention provides a PC / PBT modified plastic and its preparation method. This invention utilizes PC to provide high strength and thermal stability, while PBT enhances the material's rigidity and dimensional stability. Reinforcing agents are dispersed at the phase interface, forming a "soft phase toughening" region that absorbs impact energy and prevents crack propagation. Multiple reaction sites form a chemically bonded cross-linked structure, further improving impact performance and heat resistance.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows: The present invention proposes a PC / PBT modified plastic, wherein the modified plastic comprises the following components in parts by weight: 70-80 parts of polycarbonate (PC), 20-30 parts of maleic anhydride modified polybutylene terephthalate (maleic anhydride modified PBT), and 15-20 parts of reinforcing agent.

[0006] Preferably, the raw materials for preparing maleic anhydride modified PBT include the following components in parts by weight: 20-30 parts of terephthalic acid, 12.5-15 parts of 1,4-butanediol, 4-9.25 parts of 3-chloro-1,2-propanediol, and 3.55-8.2 parts of maleic anhydride.

[0007] Preferably, the raw materials for preparing the reinforcing agent include the following components in parts by weight: 10 parts of polypropylene glycol, 2.5-4.0 parts of diisocyanate compound, 0.8-1.2 parts of 3-allyloxy-1,2-propanediol, 8-12 parts of methyl methacrylate, 3-5 parts of hydroxyethyl acrylate, and 2.5-4.5 parts of diglycidyl ether compound;

[0008] Preferably, the diisocyanate compound includes at least one of 1,5-pentanediisocyanate (PDI), hexamethylene diisocyanate (HDI), lysine diisocyanate (LDI), and isophorone diisocyanate (IPDI);

[0009] Preferably, the diglycidyl ether compound includes at least one of glycerol diglycidyl ether, bisphenol A diglycidyl ether, ethylene glycol diglycidyl ether, bisphenol F diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol diglycidyl ether.

[0010] Preferably, the method for preparing the reinforcing agent specifically includes the following steps:

[0011] A1. Polypropylene glycol and diisocyanate compound were mixed, a catalyst was added to the reaction system, and the reaction temperature was increased to carry out a prepolymerization reaction. After the reaction was completed, 3-allyloxy-1,2-propanediol was added, the rotation speed was increased and the reaction temperature was further increased to carry out a polymerization reaction. After the reaction was completed, the mixture was washed and dried to obtain double bond modified polyurethane.

[0012] Preferably, in step A1, the mass of the catalyst added is 0.1-0.14% of the mass of polypropylene glycol;

[0013] Preferably, in step A1, the stirring speed of the prepolymerization reaction is 300-400 rpm, the reaction temperature of the prepolymerization reaction is 80-90℃, and the reaction time of the prepolymerization reaction is 2-3 h;

[0014] Preferably, in step A1, the stirring speed of the polymerization reaction is 600-700 rpm, the reaction temperature of the polymerization reaction is 100-110℃, and the reaction time of the polymerization reaction is 12-18 h;

[0015] A2. Dissolve the double-bond modified polyurethane prepared in step A1 in DMF, add methyl methacrylate and hydroxyethyl acrylate, stir to mix the reaction system evenly, add an initiator to the reaction system, raise the reaction temperature to 70-80℃ to carry out the polymerization reaction, and after the reaction is completed, hydroxylated polyurethane is obtained.

[0016] Preferably, in step A2, the mass of the initiator added is 0.3-0.4% of the total mass of methyl methacrylate and hydroxyethyl acrylate;

[0017] Preferably, in step A2, the initiator includes at least one of ammonium persulfate, sodium persulfate, and potassium persulfate;

[0018] Preferably, in step A2, the stirring speed of the polymerization reaction is 400-600 rpm, the reaction temperature of the polymerization reaction is 70-80℃, and the reaction time of the polymerization reaction is 1-2 h;

[0019] A3. Add diglycidyl ether compounds and triethylamine to the hydroxylated polyurethane reaction system prepared in step A2, raise the reaction temperature to carry out the ring-opening reaction, and after the reaction is completed, let the reaction system cool to room temperature, add saturated sodium bicarbonate aqueous solution to wash the reaction system until neutral, collect the organic phase, dry the organic phase with anhydrous magnesium sulfate, remove excess reaction solvent by rotary evaporation, and granulate to obtain modified polyurethane particles.

[0020] Preferably, in step A3, the mass-to-volume ratio of the diglycidyl ether compound to triethylamine is 0.2-0.3 g / mL;

[0021] Preferably, in step A3, the reaction temperature of the ring-opening reaction is 100-120°C, and the reaction time of the ring-opening reaction is 2-4 hours;

[0022] A4. Take the modified polyurethane particles prepared in step A3 and mix them with anhydrous ethanol. Place them at -25℃ for demulsification treatment. After the demulsification treatment is completed, place them in a drying oven for drying treatment to obtain the reinforcing agent.

[0023] Preferably, in step A4, the demulsification process takes 18-24 hours;

[0024] Preferably, in step A4, the drying temperature is 50-60°C and the drying time is 12-15 hours.

[0025] This invention also provides a method for preparing PC / PBT modified plastic, specifically including the following steps:

[0026] S1. Take terephthalic acid, 1,4-butanediol and 3-chloro-1,2-propanediol and mix them evenly. Purge with flowing nitrogen gas, add TBT catalyst, and raise the reaction temperature to carry out esterification reaction. After the reaction is completed, add dibutyltin diacetate and place under vacuum conditions. Raise the reaction temperature to carry out polycondensation reaction. After the reaction is completed, add anhydrous diethyl ether to wash and dry to obtain PBT-Cl.

[0027] Preferably, in step S1, the mass of the TBT catalyst added is 0.5%-1% of the mass of terephthalic acid;

[0028] Preferably, in step S1, the added mass of dibutyltin diacetate is 0.5%-1% of the mass of terephthalic acid;

[0029] Preferably, in step S1, the reaction temperature of the esterification reaction is 200-220℃, and the reaction time of the esterification reaction is 6-8h;

[0030] Preferably, in step S1, the reaction temperature of the polycondensation reaction is 250-270°C, and the reaction time of the polycondensation reaction is 6-8 hours.

[0031] S2. Dissolve the PBT-Cl prepared in step S1 in DMSO, add maleic anhydride and mix well, then add benzoyl peroxide, and carry out the grafting reaction by raising the reaction temperature under a nitrogen atmosphere. After the reaction is completed, add anhydrous ethanol for washing, and after drying, maleic anhydride modified polybutylene terephthalate is obtained.

[0032] Preferably, in step S2, the mass of benzoyl peroxide added is 0.2%-0.5% of the mass of maleic anhydride;

[0033] Preferably, in step S2, the grafting reaction temperature is 80-90℃ and the grafting reaction time is 4-6h;

[0034] S3. After drying the maleic anhydride modified PBT and polycarbonate prepared in step S2 at 120°C for 6 hours, they are loaded into a twin-screw extruder, a reinforcing agent is added, and the mixture is stirred at a speed of 80-100 rpm. The temperature is raised to 250-270°C for melt blending, extrusion, cooling and granulation are performed, and after drying at 120°C for 6 hours, the mixture is injection molded at 250°C to obtain PC / PBT modified plastic.

[0035] The beneficial effects achieved by this invention are as follows:

[0036] This invention provides a PC / PBT modified plastic and its preparation method. The invention provides high strength and thermal stability through PC, enhances the rigidity and dimensional stability of the material through PBT, disperses the reinforcing agent at the phase interface to form a "soft phase toughening" region, absorbs impact energy, prevents crack propagation, and forms a chemical cross-linked structure at multiple reaction sites, further improving impact performance and heat resistance. In this invention, polypropylene glycol reacts with diisocyanate to form a prepolymer, introducing flexible segments (polyether structure) into the structure, which helps to improve the overall flexibility and toughness. 3-Allyloxy-1,2-propanediol introduces double bonds, providing active sites for subsequent grafting and crosslinking reactions. The overall prepolymer with double bonds at the ends has crosslinking potential and flexibility adjustment function. Methyl methacrylate (PMMA structure) and hydroxyethyl acrylate are introduced into the double-bonded polyurethane backbone through free radical polymerization, introducing a rigid skeleton and polar groups, improving the compatibility and polar group density of the material, which helps to improve the interfacial compatibility with the PC / PBT system. Diglycidyl ether reacts with hydroxyl groups to form a crosslinking network, improving the structural integrity and heat resistance of the reinforcing agent, and improving the dispersion stability of the reinforcing agent in melt blending and the interfacial crosslinking ability with the matrix. The polyurethane part improves the flexibility and ductility, and the double bonds and hydroxyl groups enhance the reactivity and interfacial bonding force with the PC / PBT matrix. The micronized particles can achieve uniform dispersion, forming a "soft domain toughening" effect to absorb impact energy. In this invention, a polyester containing a halogenated structure (Cl) is synthesized through esterification and condensation polymerization to improve its polarity and reactivity, thereby functionalizing PBT and creating conditions for subsequent grafting reactions. Maleic anhydride is grafted onto the PBT chain using a free radical initiator (benzoyl peroxide). Maleic anhydride is a polar monomer that can significantly improve the interfacial compatibility between PBT and PC. At the same time, the introduction of anhydride groups can react with the hydroxyl or amine groups in the reinforcing agent to form ester / amide bonds to enhance crosslinking. The grafted PBT has enhanced polarity, improving its compatibility with PC, reducing phase separation, enhancing the overall mechanical stability and impact toughness of the modified material, and providing reaction sites to form a synergistic effect with the reinforcing agent. Attached Figure Description

[0037] Figure 1 The tensile properties of the PC / PBT plastics prepared in Examples 1-3 and Comparative Examples 1-2 of this invention are shown in the figure.

[0038] Figure 2 The impact strength results of the PC / PBT plastics prepared in Examples 1-3 and Comparative Examples 1-2 of this invention are shown in the figure.

[0039] Figure 3 This is an SEM image of the PC / PBT modified plastic prepared in Example 1.

[0040] The accompanying drawings are provided to further illustrate the invention and form part of the specification. They are used together with the embodiments of the invention to explain the invention and do not constitute a limitation thereof. Detailed Implementation

[0041] The technical solutions of the present invention will be clearly and completely described below with reference to the accompanying drawings of the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0042] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those familiar to those skilled in the art. Furthermore, any methods and materials similar to or equivalent to those described herein may be applied to this invention. The preferred embodiments and materials described herein are for illustrative purposes only and do not limit the scope of this application.

[0043] Unless otherwise specified, the experimental methods used in the following examples are conventional methods; unless otherwise specified, the experimental materials and test strains used in the following examples were purchased from commercial channels.

[0044] The sources of the materials used in this invention are as follows:

[0045] Example 1

[0046] This embodiment provides a PC / PBT modified plastic, which comprises the following components in parts by weight: 70 parts of polycarbonate (PC, grade 02-10R, Zhejiang Tie Dafeng), 30 parts of maleic anhydride modified polybutylene terephthalate (maleic anhydride modified PBT), and 15 parts of reinforcing agent.

[0047] The raw materials for preparing maleic anhydride modified PBT include the following components in parts by weight: 20 parts terephthalic acid, 12.5 parts 1,4-butanediol, 4 parts 3-chloro-1,2-propanediol, and 3.55 parts maleic anhydride.

[0048] The raw materials for preparing the reinforcing agent include the following components in parts by weight: 10 parts of polypropylene glycol, 2.5 parts of 1,5-pentanediisocyanate, 0.8 parts of 3-allyloxy-1,2-propanediol, 10 parts of methyl methacrylate, 5 parts of hydroxyethyl acrylate, and 3.0 parts of glycerol diglycidyl ether.

[0049] The preparation method of the reinforcing agent specifically includes the following steps:

[0050] A1. Mix 10g of polypropylene glycol with 2.5g of 1,5-pentanediisocyanate. Add 10mg of DBTDL catalyst to the reaction system and raise the reaction temperature to carry out a prepolymerization reaction. The stirring speed of the prepolymerization reaction is 400rpm, the reaction temperature is 90℃, and the reaction time is 3h. After the reaction is completed, add 0.8g of 3-allyloxy-1,2-propanediol, increase the stirring speed and further raise the reaction temperature to carry out a polymerization reaction. The stirring speed of the polymerization reaction is 600rpm, the reaction temperature is 110℃, and the reaction time is 14h. After the reaction is completed, wash and dry to obtain double bond modified polyurethane.

[0051] A2. Dissolve the double-bond modified polyurethane prepared in step A1 in DMF, add 10g of methyl methacrylate and 5g of hydroxyethyl acrylate, stir to mix the reaction system evenly, add 45mg of ammonium persulfate to the reaction system, raise the reaction temperature to carry out the polymerization reaction, the stirring speed of the polymerization reaction is 600rpm, the reaction temperature of the polymerization reaction is 80℃, the reaction time of the polymerization reaction is 1h, after the reaction is completed, hydroxylated polyurethane is obtained.

[0052] A3. Add 3.0 g of glycerol diglycidyl ether and 15 mL of triethylamine to the hydroxylated polyurethane reaction system prepared in step A2. Increase the reaction temperature to carry out the ring-opening reaction. The reaction temperature of the ring-opening reaction is 120 °C and the reaction time is 2 h. After the reaction is completed, let the reaction system cool to room temperature. Add saturated sodium bicarbonate aqueous solution to wash the reaction system until neutral. Collect the organic phase, dry the organic phase with anhydrous magnesium sulfate, remove excess reaction solvent by rotary evaporation, and granulate to obtain modified polyurethane particles.

[0053] A4. Take the modified polyurethane particles prepared in step A3 and mix them with anhydrous ethanol. Place them at -25℃ for demulsification treatment for 18 hours. After the demulsification treatment, place them in a drying oven for drying treatment at 50℃ for 15 hours to obtain the reinforcing agent.

[0054] This embodiment also provides a method for preparing PC / PBT modified plastic, specifically including the following steps:

[0055] S1. Take 4.0g of terephthalic acid, 2.5g of 1,4-butanediol, and 0.8g of 3-chloro-1,2-propanediol and mix them evenly. Purge with flowing nitrogen gas, add 30mg of TBT catalyst, and raise the reaction temperature to carry out the esterification reaction. The reaction temperature of the esterification reaction is 220℃ and the reaction time is 8h. After the reaction is completed, add 30mg of dibutyltin diacetate, place under vacuum, and raise the reaction temperature to carry out the polycondensation reaction. The reaction temperature of the polycondensation reaction is 250℃ and the reaction time is 8h. After the reaction is completed, wash with anhydrous diethyl ether and dry to obtain PBT-Cl.

[0056] S2. Dissolve the PBT-Cl prepared in step S1 in DMSO, add 0.7g of maleic anhydride and mix well, then add 3.5mg of benzoyl peroxide. Under a nitrogen atmosphere, raise the reaction temperature to carry out the grafting reaction. The reaction temperature of the grafting reaction is 90℃ and the reaction time of the grafting reaction is 4h. After the reaction is completed, add anhydrous ethanol for washing and dry to obtain maleic anhydride modified PBT.

[0057] S3. After drying 70 parts of maleic anhydride modified PBT and 30 parts of polycarbonate prepared in step S2 at 120°C for 6 hours, they are loaded into a twin-screw extruder, 15 parts of reinforcing agent are added, and the mixture is stirred at 80 rpm. The temperature is increased to 260°C for melt blending, extruded, cooled and granulated, dried at 120°C for 6 hours, and then injection molded at 250°C to obtain PC / PBT modified plastic.

[0058] Example 2

[0059] This embodiment provides a PC / PBT modified plastic, which comprises the following components in parts by weight: 80 parts of polycarbonate (PC, grade 02-10R, Zhejiang Tie Dafeng), 20 parts of maleic anhydride modified polybutylene terephthalate (maleic anhydride modified PBT), and 18 parts of reinforcing agent.

[0060] The raw materials for preparing maleic anhydride modified PBT include the following components in parts by weight: 25 parts terephthalic acid, 14 parts 1,4-butanediol, 6 parts 3-chloro-1,2-propanediol, and 5.5 parts maleic anhydride.

[0061] The raw materials for preparing the reinforcing agent include the following components in parts by weight: 10 parts of polypropylene glycol, 3.0 parts of hexamethylene diisocyanate, 1.0 part of 3-allyloxy-1,2-propanediol, 8 parts of methyl methacrylate, 4 parts of hydroxyethyl acrylate, and 2.5 parts of bisphenol F diglycidyl ether.

[0062] The preparation method of the reinforcing agent specifically includes the following steps:

[0063] A1. Mix 15g of polypropylene glycol with 3.0g of hexamethylene diisocyanate. Add 12mg of DBTDL catalyst to the reaction system and raise the reaction temperature to carry out a prepolymerization reaction. The stirring speed of the prepolymerization reaction is 400rpm, the reaction temperature is 80℃, and the reaction time is 2h. After the reaction is completed, add 1.0g of 3-allyloxy-1,2-propanediol, increase the stirring speed and further raise the reaction temperature to carry out a polymerization reaction. The stirring speed of the polymerization reaction is 700rpm, the reaction temperature is 100℃, and the reaction time is 12h. After the reaction is completed, wash and dry to obtain double bond modified polyurethane.

[0064] A2. Dissolve the double-bond modified polyurethane prepared in step A1 in DMF, add 8g of methyl methacrylate and 4g of hydroxyethyl acrylate, stir to mix the reaction system evenly, add 42mg of ammonium persulfate to the reaction system, raise the reaction temperature to carry out the polymerization reaction, the stirring speed of the polymerization reaction is 400rpm, the reaction temperature of the polymerization reaction is 75℃, the reaction time of the polymerization reaction is 2h, after the reaction is completed, hydroxylated polyurethane is obtained.

[0065] A3. Add 2.5 g of bisphenol F diglycidyl ether and 10 mL of triethylamine to the hydroxylated polyurethane reaction system prepared in step A2. Increase the reaction temperature to carry out the ring-opening reaction. The reaction temperature of the ring-opening reaction is 100℃ and the reaction time is 3 h. After the reaction is completed, let the reaction system cool to room temperature, add saturated sodium bicarbonate aqueous solution to wash the reaction system until neutral, collect the organic phase, dry the organic phase with anhydrous magnesium sulfate, remove excess reaction solvent by rotary evaporation, and granulate to obtain modified polyurethane particles.

[0066] A4. Take the modified polyurethane particles prepared in step A3 and mix them with anhydrous ethanol. Place them at -25℃ for demulsification treatment for 24 hours. After the demulsification treatment, place them in a drying oven for drying treatment at 55℃ for 12 hours to obtain the reinforcing agent.

[0067] This embodiment also provides a method for preparing PC / PBT modified plastic, specifically including the following steps:

[0068] S1. Take 5.0g of terephthalic acid, 2.8g of 1,4-butanediol, and 1.2g of 3-chloro-1,2-propanediol and mix them evenly. Purge with flowing nitrogen gas, add 50mg of TBT catalyst, and raise the reaction temperature to carry out the esterification reaction. The reaction temperature of the esterification reaction is 200℃ and the reaction time is 6h. After the reaction is completed, add 50mg of dibutyltin diacetate, place under vacuum, and raise the reaction temperature to carry out the polycondensation reaction. The reaction temperature of the polycondensation reaction is 260℃ and the reaction time is 7h. After the reaction is completed, wash with anhydrous diethyl ether and dry to obtain PBT-Cl.

[0069] S2. Dissolve the PBT-Cl prepared in step S1 in DMSO, add 1.1g of maleic anhydride and mix well, then add 3.3mg of benzoyl peroxide. Under a nitrogen atmosphere, raise the reaction temperature to carry out the grafting reaction. The reaction temperature of the grafting reaction is 80℃ and the reaction time is 6h. After the reaction is completed, add anhydrous ethanol for washing and dry to obtain maleic anhydride modified PBT.

[0070] S3. After drying 80 parts of maleic anhydride modified PBT and 20 parts of polycarbonate prepared in step S2 at 120°C for 6 hours, they are loaded into a twin-screw extruder, 18 parts of reinforcing agent are added, and the mixture is stirred at 90 rpm. The temperature is increased to 250°C for melt blending, extruded, cooled and granulated, dried at 120°C for 6 hours, and then injection molded at 250°C to obtain PC / PBT modified plastic.

[0071] Example 3

[0072] This embodiment provides a PC / PBT modified plastic, which comprises the following components in parts by weight: 75 parts of polycarbonate (PC, grade 02-10R, Zhejiang Tie Dafeng), 25 parts of maleic anhydride modified polybutylene terephthalate (maleic anhydride modified PBT), and 20 parts of reinforcing agent.

[0073] The raw materials for preparing maleic anhydride-modified PBT include the following components in parts by weight: 30 parts terephthalic acid, 15 parts 1,4-butanediol, 9.25 parts 3-chloro-1,2-propanediol, and 8.2 parts maleic anhydride.

[0074] The raw materials for preparing the reinforcing agent include the following components in parts by weight: 10 parts of polypropylene glycol, 4.0 parts of lysine diisocyanate, 0.8 parts of 3-allyloxy-1,2-propanediol, 12 parts of methyl methacrylate, 3 parts of hydroxyethyl acrylate, and 4.5 parts of 1,6-hexanediol diglycidyl ether.

[0075] The preparation method of the reinforcing agent specifically includes the following steps:

[0076] A1. Mix 20g of polypropylene glycol with 4.0g of lysine diisocyanate. Add 14mg of DBTDL catalyst to the reaction system and raise the reaction temperature to carry out a prepolymerization reaction. The stirring speed of the prepolymerization reaction is 400rpm, the reaction temperature is 90℃, and the reaction time is 2h. After the reaction is completed, add 1.2g of 3-allyloxy-1,2-propanediol, increase the stirring speed and further raise the reaction temperature to carry out a polymerization reaction. The stirring speed of the polymerization reaction is 600rpm, the reaction temperature is 100℃, and the reaction time is 18h. After the reaction is completed, wash and dry to obtain double bond modified polyurethane.

[0077] A2. Dissolve the double-bond modified polyurethane prepared in step A1 in DMF, add 12g of methyl methacrylate and 3g of hydroxyethyl acrylate, stir to mix the reaction system evenly, add 60mg of ammonium persulfate to the reaction system, raise the reaction temperature to carry out the polymerization reaction, the stirring speed of the polymerization reaction is 500rpm, the reaction temperature of the polymerization reaction is 70℃, the reaction time of the polymerization reaction is 1.5h, after the reaction is completed, hydroxylated polyurethane is obtained;

[0078] A3. Add 4.5 g of 1,6-hexanediol diglycidyl ether and 13.5 mL of triethylamine to the hydroxylated polyurethane reaction system prepared in step A2. Increase the reaction temperature to carry out the ring-opening reaction. The reaction temperature of the ring-opening reaction is 110℃ and the reaction time is 4 h. After the reaction is completed, let the reaction system cool to room temperature, add saturated sodium bicarbonate aqueous solution to wash the reaction system until neutral, collect the organic phase, dry the organic phase with anhydrous magnesium sulfate, remove excess reaction solvent by rotary evaporation, and granulate to obtain modified polyurethane particles.

[0079] A4. Take the modified polyurethane particles prepared in step A3 and mix them with anhydrous ethanol. Place them at -25℃ for demulsification treatment for 21 hours. After the demulsification treatment, place them in a drying oven for drying treatment at a temperature of 60℃ for 14 hours to obtain the reinforcing agent.

[0080] This embodiment also provides a method for preparing PC / PBT modified plastic, specifically including the following steps:

[0081] S1. Take 6.0g of terephthalic acid, 3.0g of 1,4-butanediol, and 1.85g of 3-chloro-1,2-propanediol, mix them evenly, introduce flowing nitrogen gas, add 30mg of TBT catalyst, and raise the reaction temperature to carry out the esterification reaction. The reaction temperature of the esterification reaction is 210℃, and the reaction time is 7h. After the reaction is completed, add 30mg of dibutyltin diacetate, place it under vacuum, and raise the reaction temperature to carry out the polycondensation reaction. The reaction temperature of the polycondensation reaction is 270℃, and the reaction time is 6h. After the reaction is completed, wash with anhydrous diethyl ether, and dry to obtain PBT-Cl.

[0082] S2. Dissolve the PBT-Cl prepared in step S1 in DMSO, add 1.65g of maleic anhydride and mix well, then add 3.3mg of benzoyl peroxide. Under a nitrogen atmosphere, raise the reaction temperature to carry out the grafting reaction. The reaction temperature of the grafting reaction is 85℃ and the reaction time is 5h. After the reaction is completed, add anhydrous ethanol for washing and dry to obtain maleic anhydride modified PBT.

[0083] S3. After drying 75 parts of maleic anhydride modified PBT and 25 parts of polycarbonate prepared in step S2 at 120°C for 6 hours, they are loaded into a twin-screw extruder, 20 parts of reinforcing agent are added, and the mixture is stirred at 100 rpm. The temperature is increased to 270°C for melt blending, extruded, cooled and granulated, dried at 120°C for 6 hours, and then injection molded at 250°C to obtain PC / PBT modified plastic.

[0084] Comparative Example 1

[0085] This comparative example provides a PC / PBT plastic and its preparation method. The only difference between this example and Example 1 is that no reinforcing agent is included in any of the components, while the remaining components and their contents are the same as in Example 1.

[0086] Comparative Example 2

[0087] This comparative example provides a PC / PBT plastic and its preparation method. The only difference between this example and Example 1 is that maleic anhydride modified PBT is replaced with the same weight parts of PBT in all components, while the other components and their contents are the same as in Example 1.

[0088] Comparative Example 3

[0089] This comparative example provides a PC / PBT plastic and its preparation method. The only difference between this example and Example 1 is that the raw materials for preparing the reinforcing agent include only polypropylene glycol and 1,5-pentanediisocyanate, and the preparation method of the reinforcing agent includes only step A1. In step A1, after the prepolymerization reaction is completed, the rotation speed is increased and the reaction temperature is further increased to carry out the polymerization reaction to obtain the reinforcing agent. The remaining components and component contents are the same as in Example 1.

[0090] Experimental Example

[0091] The PC / PBT plastics prepared in Examples 1-3 and Comparative Examples 1-3 were injection molded into standard tensile and impact specimens using a micro-plastic injection molding machine at a temperature of 265°C. The standard impact specimens were punched with a V-shaped notch of 2 mm using an automatic notch-making machine and placed at room temperature for 24 hours to relieve stress before being used for mechanical property testing.

[0092] 1. Tensile properties were tested according to GB-T 528-2009 at 25℃ and a tensile rate of 50 mm / min on a universal tensile testing machine. Five specimens were tested for each sample, and the average value was taken.

[0093] Figure 1 The figure shows the tensile properties of the PC / PBT plastics prepared in Examples 1-3 and Comparative Examples 1-3 of this invention. As shown in the figure, due to the addition of the reinforcing agent, the PC / PBT plastic presents a ternary blend system. The tensile strength of the reinforcing agent itself is lower than that of the PC / PBT binary alloy. After mixing, a three-dimensional cross-linked network is formed, which leads to an increase in the tensile strength of the overall blend system.

[0094] 2. Impact performance testing was conducted according to GB / T 9341-2008 at 25℃. A V-shaped notch was punched into the injection-molded specimen using a notch-making machine. After being placed at 25℃ for 24 hours, the specimens were tested. Five specimens were tested for each type of sample, and the average value was taken.

[0095] Figure 2 The figures show the impact strength results of the PC / PBT plastics prepared in Examples 1-3 and Comparative Examples 1-3 of this invention. As shown, with the addition of the reinforcing agent, the solubility parameters of polyacrylate, PBT, and PC are quite similar. Therefore, maleic anhydride can have a good interface between the matrix and the rubber particles, forming a homogeneous phase with PBT and PC during extrusion. The rubber phase is distributed in a particle state within the continuous PBT and PC phases, thus giving the entire system an "island" structure. This structure also endows the blend system with good impact resistance.

[0096] 3. The heat resistance was tested according to GB / T 1634.2-2019. The load heat distortion temperature of the PC / PBT plastics prepared in Examples 1-3 and Comparative Examples 1-3 was determined using a D-44149 microcalorie heat distortion tester. The test conditions were set as follows: load A (1.82MPa), heating rate of 2℃ / min, support span of 100mm±1mm, and sample thickness of 4mm.

[0097] Figure 3The figure shows the heat distortion temperature results of PC / PBT plastics prepared in Examples 1-3 and Comparative Examples 1-3. As shown in the figure, the heat distortion temperature of PC / PBT plastics prepared in Examples 1-3 remained above 95°C, while the heat distortion temperature of PC / PBT plastics prepared in Comparative Example 1 was the lowest, indicating poor heat resistance. The heat resistance of Comparative Examples 2 and 3 was similar, but differed significantly from those of the Examples.

[0098] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention.

[0099] The present invention and its embodiments have been described above. This description is not restrictive, and the accompanying drawings are only one embodiment of the present invention. The actual application is not limited to this. In conclusion, if those skilled in the art are inspired by this description and design similar methods and embodiments without departing from the spirit of the present invention, they should all fall within the protection scope of the present invention.

Claims

1. A PC / PBT modified plastic, characterized in that: The modified plastic comprises the following components in parts by weight: 70-80 parts polycarbonate, 20-30 parts maleic anhydride-modified polybutylene terephthalate, and 15-20 parts reinforcing agent; the raw materials for preparing the maleic anhydride-modified polybutylene terephthalate comprise the following components in parts by weight: 20-30 parts terephthalic acid, 12.5-15 parts 1,4-butanediol, 4-9.25 parts 3-chloro-1,2-propanediol, and 3.55-8.2 parts maleic anhydride; the raw materials for preparing the reinforcing agent comprise the following components in parts by weight: 10 parts polypropylene glycol, 2.5-4.0 parts diisocyanate compound, and 3-ene... The composition includes 0.8-1.2 parts propoxy-1,2-propanediol, 8-12 parts methyl methacrylate, 3-5 parts hydroxyethyl acrylate, and 2.5-4.5 parts diglycidyl ether compounds; the diisocyanate compounds include at least one selected from 1,5-pentanediisocyanate, hexamethylene diisocyanate, lysine diisocyanate, and isophorone diisocyanate; the diglycidyl ether compounds include at least one selected from glycerol diglycidyl ether, bisphenol A diglycidyl ether, ethylene glycol diglycidyl ether, bisphenol F diglycidyl ether, neopentyl glycol diglycidyl ether, and 1,6-hexanediol diglycidyl ether. The preparation method of the reinforcing agent specifically includes the following steps: A1. Polypropylene glycol and diisocyanate compounds are mixed, a catalyst is added to the reaction system, and the reaction temperature is increased to carry out a prepolymerization reaction. After the reaction is completed, 3-allyloxy-1,2-propanediol is added, the rotation speed is increased and the reaction temperature is further increased to carry out a polymerization reaction. After the reaction is completed, the mixture is washed and dried to obtain double-bonded polyurethane. A2. Dissolve the double-bond modified polyurethane prepared in step A1 in DMF, add methyl methacrylate and hydroxyethyl acrylate, stir to mix the reaction system evenly, add an initiator to the reaction system, raise the reaction temperature to 70-80℃ to carry out the polymerization reaction, and after the reaction is completed, hydroxylated polyurethane is obtained. A3. Add diglycidyl ether compounds and triethylamine to the hydroxylated polyurethane reaction system prepared in step A2, raise the reaction temperature to carry out the ring-opening reaction, and after the reaction is completed, let the reaction system cool to room temperature, add saturated sodium bicarbonate aqueous solution to wash the reaction system until neutral, collect the organic phase, dry the organic phase with anhydrous magnesium sulfate, remove excess reaction solvent by rotary evaporation, and granulate to obtain modified polyurethane particles. A4. Take the modified polyurethane particles prepared in step A3 and mix them with anhydrous ethanol. Place them at -25℃ for demulsification treatment. After the demulsification treatment, place them in a desiccant for drying treatment to obtain the reinforcing agent.

2. The PC / PBT modified plastic according to claim 1, characterized in that: In step A1, the mass of the catalyst added is 0.1-0.14% of the mass of polypropylene glycol; the stirring speed of the prepolymerization reaction is 300-400 rpm, the reaction temperature of the prepolymerization reaction is 80-90℃, and the reaction time of the prepolymerization reaction is 2-3 h; the stirring speed of the polymerization reaction is 600-700 rpm, the reaction temperature of the polymerization reaction is 100-110℃, and the reaction time of the polymerization reaction is 12-18 h.

3. The PC / PBT modified plastic according to claim 2, characterized in that: In step A2, the initiator is added at a mass of 0.3-0.4% of the total mass of methyl methacrylate and hydroxyethyl acrylate; the initiator includes at least one of ammonium persulfate, sodium persulfate and potassium persulfate; the stirring speed of the polymerization reaction is 400-600 rpm, the reaction temperature of the polymerization reaction is 70-80℃, and the reaction time of the polymerization reaction is 1-2 h.

4. The PC / PBT modified plastic according to claim 3, characterized in that: In step A3, the mass-to-volume ratio of the diglycidyl ether compound to triethylamine is 0.2-0.3 g / mL; the ring-opening reaction temperature is 100-120℃, and the ring-opening reaction time is 2-4 h.

5. The PC / PBT modified plastic according to claim 4, characterized in that: In step A4, the demulsification process takes 18-24 hours; the drying process takes 12-15 hours at a temperature of 50-60°C.

6. A method for preparing PC / PBT modified plastic according to claim 5, characterized in that: Specifically, the following steps are included: S1. Take terephthalic acid, 1,4-butanediol and 3-chloro-1,2-propanediol and mix them evenly. Purge with flowing nitrogen gas, add TBT catalyst, and raise the reaction temperature to carry out esterification reaction. After the reaction is completed, add dibutyltin diacetate and place under vacuum conditions. Raise the reaction temperature to carry out polycondensation reaction. After the reaction is completed, add anhydrous diethyl ether to wash and dry to obtain PBT-Cl. S2. Dissolve the PBT-Cl prepared in step S1 in DMSO, add maleic anhydride and mix well, then add benzoyl peroxide, and carry out the grafting reaction by raising the reaction temperature under a nitrogen atmosphere. After the reaction is completed, add anhydrous ethanol for washing, and after drying, maleic anhydride modified polybutylene terephthalate is obtained. S3. After drying the maleic anhydride-grafted PBT and polycarbonate prepared in step S2 at 120°C for 6 hours, they are loaded into a twin-screw extruder, a reinforcing agent is added, and the mixture is stirred at 80-100 rpm. The temperature is raised to 250-270°C for melt blending, extruded, cooled and granulated, and dried at 120°C for 6 hours. Then, it is injection molded at 250°C to obtain PC / PBT modified plastic.

7. The method for preparing PC / PBT modified plastic according to claim 6, characterized in that: In step S1, the mass of the TBT catalyst added is 0.5%-1% of the mass of terephthalic acid; the mass of the dibutyltin diacetate added is 0.5%-1% of the mass of terephthalic acid.

8. The method for preparing PC / PBT modified plastic according to claim 7, characterized in that: In step S1, the esterification reaction temperature is 200-220℃, and the esterification reaction time is 6-8h.

9. The method for preparing PC / PBT modified plastic according to claim 8, characterized in that: In step S1, the reaction temperature of the polycondensation reaction is 250-270℃, and the reaction time is 6-8h.

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