Preparation and application of high-transmittance polycarbonate nanoparticle composite materials

Abstract

The present invention discloses the preparation and application of a high-transmittance polycarbonate nanoparticle composite material. The invention relates to the technical field of polymer materials and comprises the following specific steps: Step 1: selecting acrylic acid containing a carboxyl group and epichlorohydrin containing an epoxy group as raw materials, adding the raw materials into a reactor, and adding tetrabutylammonium bromide under nitrogen protection to carry out a ring-opening addition reaction. The advantages of the present invention are: a novel coupling agent is prepared by selecting acrylic acid and epichlorohydrin, and a coupling agent with a unique structure is generated under nitrogen protection and the action of a catalyst; polycarbonate is heated and melted, and then nano-titanium dioxide particles with pre-treated surface are added together with the novel coupling agent into a twin-screw extruder and fully mixed. The high-transmittance polycarbonate nanoparticle composite material is finally obtained, and its interfacial compatibility is greatly improved, the debonding phenomenon between the nanoparticles and the polycarbonate matrix is effectively avoided, and the mechanical properties of the material are significantly improved.

Description

Technical Field

[0001] The present invention relates to the technical field of polymer materials, in particular to the preparation and application of a high-transmittance polycarbonate nanoparticle composite material. Background Art

[0002] In today's vast field of materials science, polycarbonate stands out for its excellent comprehensive performance, becoming one of the most sought-after polymer materials. Polycarbonate has excellent optical transparency, with a light transmittance of up to 85%-90%. This makes it extremely widely used in many fields with strict transparency requirements, such as optical instruments, electronic display devices, and automotive windshields. Polycarbonate also has excellent mechanical properties, such as high strength, high toughness, and excellent impact resistance. It can maintain stable performance in different usage environments, effectively ensuring product safety and reliability.

[0003] The existing technology has certain defects. The first is interface compatibility. The chemical properties of polycarbonate and nanoparticles are very different, resulting in a lack of good interaction between the two interfaces, and the inability to form effective chemical bonds or strong physical adsorption. This makes it easy for debonding to occur between the nanoparticles and the polycarbonate matrix when subjected to force, and the reinforcing effect of the nanoparticles cannot be fully exerted, limiting the improvement of the mechanical properties of the composite material. The second is the high melt viscosity. The melt viscosity of polycarbonate itself is relatively high. After the addition of nanoparticles, the viscosity of the system is further increased, resulting in poor fluidity during processing. This not only increases the difficulty of molding processing, but may also cause defects in the product, such as incomplete mold filling, uneven surface, and other problems, which limit the molding process selection and product quality of the composite material. For this reason, we propose the preparation and application of high-transmittance polycarbonate nanoparticle composite materials. Summary of the Invention

[0004] The purpose of the present invention is to provide preparation and application of high-transmittance polycarbonate nanoparticle composite material.

[0005] To solve the problems raised in the above background technology, the present invention provides the following technical solution: Preparation of a high-transmittance polycarbonate nanoparticle composite material, including a preparation process, wherein the preparation process includes the following specific steps:

[0006] Step 1: Selecting acrylic acid containing a carboxyl group and epichlorohydrin containing an epoxy group as raw materials, adding the raw materials to a reactor, adding tetrabutylammonium bromide under nitrogen protection to carry out a ring-opening addition reaction, after the reaction is completed, transferring the product to a separatory funnel for extraction, separating the organic phase, and then removing ether and unreacted raw materials by reduced pressure distillation to obtain a high-purity new coupling agent;

[0007] Step 2: Using polyethylene glycol as the base raw material, polyethylene glycol is added to a reactor under nitrogen protection, maleic anhydride is added to the reactor to react, and then dibenzoyl peroxide is added as an initiator to react again. After the reaction is completed, the product is dissolved in chloroform and then added dropwise to methanol for precipitation. After filtering and drying, a purified modifier is obtained;

[0008] Step 3: Dispersing the nano-titanium dioxide particles in anhydrous ethanol and performing ultrasonic treatment to uniformly disperse them, then adding 3-aminopropyltriethoxysilane as a surface modifier, stirring and reacting in an oil bath to introduce amino functional groups on the surface of the nanoparticles. After the reaction is completed, the mixed solution is transferred to a centrifuge tube and centrifuged to separate the modified nanoparticles by centrifugation. The product is then washed with anhydrous ethanol and dried to obtain surface-pretreated nano-titanium dioxide particles for later use;

[0009] Step 4: dissolving the polycarbonate in dichloromethane, slowly adding allyl glycidyl ether and azobisisobutyronitrile as initiators while stirring, and reacting in a constant temperature water bath to cause a grafting reaction between the allyl glycidyl ether and the polycarbonate molecular chain, thereby introducing a branched structure on the polycarbonate molecular chain. After the reaction is completed, the reaction solution is poured into a sufficient amount of methanol for precipitation, and the solid obtained after filtration is dried in a vacuum drying oven to obtain the modified polycarbonate;

[0010] Step 5: Add the modified polycarbonate to the hopper of the twin-screw extruder and heat it to a molten state. Then, add the purified modifier and stir it to fully disperse the modifier in the polycarbonate melt. Then, mix the surface pretreated nano-titanium dioxide particles and the new coupling agent evenly. Then, add it to the twin-screw extruder through a side feeding device and fully mix it with the molten polycarbonate to allow the coupling agent to react chemically between the nanoparticles and the polycarbonate to form a good interface bonding. After the extruded material is water-cooled and stretched, it is cut into particles by a pelletizer to obtain a high-transmittance polycarbonate nanoparticle composite material.

[0011] As a further embodiment of the present invention: in step 1, acrylic acid and epichlorohydrin are added to a reactor in a molar ratio of 1.5-2.5:1, and tetrabutylammonium bromide is added as a catalyst in an amount of 2%-4% by weight of the total raw materials. The reaction temperature is controlled at 75° C.-85° C., and the reaction time is controlled at 5 h-7 h.

[0012] As a further solution of the present invention: in the step 1, after the reaction is completed, the product is transferred to a separatory funnel, and ether is added in a volume ratio of 1:2-3 between the product and ether for extraction.

[0013] As a further embodiment of the present invention: in step 2, the molecular weight of the basic raw material polyethylene glycol is 300-500, and the molar ratio of polyethylene glycol to maleic anhydride is 1:1.1-1.3. Subsequently, the reactor is heated to 115°C-125°C, and 0.8%-1.2% of dibenzoyl peroxide by weight of the total raw material is added as an initiator. The reaction is carried out for 2.5h-3.5h to graft the maleic anhydride onto the polyethylene glycol molecular chain to obtain a new melt flow modifier.

[0014] As a further solution of the present invention: in the step 2, when the product is dissolved in chloroform, chloroform is added according to a mass ratio of product to chloroform of 1:5-10, and then added dropwise into methanol for precipitation, and after filtering, dried in a vacuum drying oven at 55°C-65°C for 20h-28h.

[0015] As a further embodiment of the present invention: in the step three, the nano-titanium dioxide particles are dispersed in anhydrous ethanol, the mass ratio of the nano-titanium dioxide particles to ethanol is 1:15-25, and ultrasonic treatment is performed for 25-35 minutes. Subsequently, 3-aminopropyltriethoxysilane accounting for 8%-12% of the mass of the nanoparticles is added as a surface modifier, and the reaction is stirred in an oil bath at 55°C-65°C for 3.5h-4.5h.

[0016] As a further solution of the present invention: in step three, the centrifuge tube is centrifuged at a speed of 4000r / min-6000r / min for 10min-15min, and then the product is washed with anhydrous ethanol 2-4 times and dried in a vacuum drying oven at 75℃-85℃ for 10h-14h.

[0017] As a further embodiment of the present invention: in the step 4, the mass ratio of polycarbonate to dichloromethane is 1:8-12, and 4%-6% of allyl glycidyl ether by mass of the polycarbonate and 0.4%-0.6% of azobisisobutyronitrile by mass of the polycarbonate are slowly added as initiators while stirring, and the reaction is carried out in a constant temperature water bath at 55°C-65°C for 7h-9h. The solid obtained after filtration is dried in a vacuum drying oven at 75°C-85°C for 10h-14h.

[0018] As a further scheme of the present invention: in the step five, the modified polycarbonate is added to the hopper of a twin-screw extruder and heated to a molten state, the temperature of zone one is set to 215°C-225°C, the temperature of zone two is set to 225°C-235°C, and the temperature of zone three is set to 235°C-245°C, and then a purified modifier accounting for 2%-4% of the mass of the modified polycarbonate is added, the screw speed is controlled at 180r / min-220r / min, and stirred for 12min-18min. Subsequently, the surface pretreated nano-titanium dioxide particles and the new coupling agent are evenly mixed in a mass ratio of 8-12:1, the screw speed of the extruder is adjusted to 280r / min-320r / min, the residence time is 4min-6min, and after water-cooling and drawing, the particles are cut into particles with a particle size of 2.5mm-3.5mm using a pelletizer.

[0019] In addition, the present invention also provides applications of high-transmittance polycarbonate nanoparticle composite materials, which are used in optical display, automobile manufacturing, construction, medical equipment and aerospace fields.

[0020] By adopting the above technical solution, compared with the prior art, the beneficial effects of the present invention are:

[0021] 1. The present invention uses acrylic acid and epichlorohydrin to prepare a novel coupling agent. Under nitrogen protection and the action of a catalyst, a coupling agent with a unique structure is generated. The carboxyl active group at one end of the coupling agent can undergo esterification or transesterification with hydroxyl groups, ester groups, etc. on the polycarbonate molecular chain, tightly connecting the polycarbonate. The other end group can specifically bind to the nanoparticles. The nano-titanium dioxide particles are first dispersed in anhydrous ethanol and then surface-modified with 3-aminopropyltriethoxysilane to introduce amino functional groups on the particle surface. This process makes the surface properties of the nanoparticles more compatible with the polycarbonate, creates a large number of binding sites for the coupling agent, and significantly enhances the affinity between the two. When preparing the composite material, the polycarbonate is heated and melted, and the surface-pretreated nano-titanium dioxide particles and the novel coupling agent are then added to a twin-screw extruder and thoroughly mixed. The resulting high-transmittance polycarbonate nanoparticle composite material has greatly improved interfacial compatibility, effectively avoids debonding between the nanoparticles and the polycarbonate matrix, and significantly improves the mechanical properties of the material.

[0022] 2. The present invention uses polyethylene glycol as the base material and introduces maleic anhydride to prepare a new melt flow modifier. On the basis of the original flexible chain of polyethylene glycol, polar and active maleic anhydride groups are introduced. On the one hand, these maleic anhydride groups can produce certain interactions with polycarbonate molecular chains, including dipole-dipole interactions or hydrogen bonding. On the other hand, their reactive double bond structures may participate in the formation of some weak chemical crosslinks or physical entanglements at high temperatures, so that the distance between molecular chains can be adjusted, and they will not be as densely packed as unmodified polycarbonate. This unique molecular structure enables the modifier to be interspersed between polycarbonate molecular chains, weakening the interaction force between molecular chains, thereby effectively reducing the melt viscosity of the system and significantly improving the processing fluidity of polycarbonate. In the pre-modification process of polycarbonate, it is dissolved and added Allyl glycidyl ether is added and reacted in a constant temperature water bath under the action of an initiator, so that allyl glycidyl ether undergoes a grafting reaction with the polycarbonate molecular chain, introducing a branched structure. This not only destroys the regularity of the polycarbonate molecular chain, further reduces the melt viscosity, but also creates conditions for subsequent better fusion with nanoparticles and modifiers. When preparing the composite material, the modified polycarbonate is first heated and melted, the new melt flow modifier is added and fully stirred and dispersed, and then the nanoparticles are added to ensure that they are evenly dispersed in the system. Finally, the high-transmittance polycarbonate nanoparticle composite material product obtained by injection molding can effectively overcome the problem of high melt viscosity while maintaining high transmittance, which not only greatly improves the processing performance, reduces the molding difficulty, but also reduces the probability of defects such as insufficient mold filling and uneven surface in the product. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 Schematic diagram of the preparation process in an embodiment of the present invention. DETAILED DESCRIPTION

[0024] The specific embodiments of the present invention will be further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention.

[0025] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0026] Please see the attached Figure 1 The preparation of the high-transmittance polycarbonate nanoparticle composite material of the present invention includes a preparation process, which includes the following specific steps:

[0027] Step 1: Selecting acrylic acid containing a carboxyl group and epichlorohydrin containing an epoxy group as raw materials, adding the raw materials to a reactor, adding tetrabutylammonium bromide under nitrogen protection to carry out a ring-opening addition reaction, after the reaction is completed, transferring the product to a separatory funnel for extraction, separating the organic phase, and then removing ether and unreacted raw materials by reduced pressure distillation to obtain a high-purity new coupling agent;

[0028] Step 2: Using polyethylene glycol as the base raw material, polyethylene glycol is added to a reactor under nitrogen protection, maleic anhydride is added to the reactor to react, and then dibenzoyl peroxide is added as an initiator to react again. After the reaction is completed, the product is dissolved in chloroform and then added dropwise to methanol for precipitation. After filtering and drying, a purified modifier is obtained;

[0029] Step 3: Dispersing the nano-titanium dioxide particles in anhydrous ethanol and performing ultrasonic treatment to uniformly disperse them, then adding 3-aminopropyltriethoxysilane as a surface modifier, stirring and reacting in an oil bath to introduce amino functional groups on the surface of the nanoparticles. After the reaction is completed, the mixed solution is transferred to a centrifuge tube and centrifuged to separate the modified nanoparticles by centrifugation. The product is then washed with anhydrous ethanol and dried to obtain surface-pretreated nano-titanium dioxide particles for later use;

[0030] Step 4: dissolving the polycarbonate in dichloromethane, slowly adding allyl glycidyl ether and azobisisobutyronitrile as initiators while stirring, and reacting in a constant temperature water bath to cause a grafting reaction between the allyl glycidyl ether and the polycarbonate molecular chain, thereby introducing a branched structure on the polycarbonate molecular chain. After the reaction is completed, the reaction solution is poured into a sufficient amount of methanol for precipitation, and the solid obtained after filtration is dried in a vacuum drying oven to obtain the modified polycarbonate;

[0031] Step 5: Add the modified polycarbonate to the hopper of the twin-screw extruder and heat it to a molten state. Then, add the purified modifier and stir it to fully disperse the modifier in the polycarbonate melt. Then, mix the surface pretreated nano-titanium dioxide particles and the new coupling agent evenly. Then, add it to the twin-screw extruder through a side feeding device and fully mix it with the molten polycarbonate to allow the coupling agent to react chemically between the nanoparticles and the polycarbonate to form a good interface bonding. After the extruded material is water-cooled and stretched, it is cut into particles by a pelletizer to obtain a high-transmittance polycarbonate nanoparticle composite material.

[0032] In one embodiment of the present invention: in step 1, acrylic acid and epichlorohydrin are added to a reactor in a molar ratio of 1.5-2.5:1, and tetrabutylammonium bromide is added as a catalyst in an amount of 2%-4% by weight of the total raw materials. The reaction temperature is controlled at 75° C.-85° C., and the reaction time is controlled at 5 h-7 h.

[0033] In one embodiment of the present invention: in step 1, after the reaction is completed, the product is transferred to a separatory funnel, and diethyl ether is added in a volume ratio of product to diethyl ether of 1:2-3 for extraction.

[0034] In one embodiment of the present invention: in step 2, the molecular weight of the basic raw material polyethylene glycol is 300-500, and the molar ratio of polyethylene glycol to maleic anhydride is 1:1.1-1.3. Subsequently, the reactor is heated to 115°C-125°C, and 0.8%-1.2% of dibenzoyl peroxide by weight of the total raw material is added as an initiator. The reaction is carried out for 2.5h-3.5h to graft the maleic anhydride onto the polyethylene glycol molecular chain to obtain a new melt flow modifier.

[0035] In one embodiment of the present invention: in step 2, when the product is dissolved in chloroform, chloroform is added according to a mass ratio of product to chloroform of 1:5-10, and then added dropwise into methanol for precipitation, and after filtering, dried in a vacuum drying oven at 55°C-65°C for 20h-28h.

[0036] In one embodiment of the present invention: In step three, nano-titanium dioxide particles are dispersed in anhydrous ethanol, the mass ratio of nano-titanium dioxide particles to ethanol is 1:15-25, and ultrasonic treatment is performed for 25 minutes to 35 minutes. Subsequently, 3-aminopropyltriethoxysilane accounting for 8% to 12% of the mass of the nanoparticles is added as a surface modifier, and the reaction is stirred in an oil bath at 55°C to 65°C for 3.5 hours to 4.5 hours.

[0037] In one embodiment of the present invention: in step 3, the centrifuge tube is centrifuged at a speed of 4000r / min-6000r / min for 10min-15min, and then the product is washed with anhydrous ethanol 2-4 times and dried in a vacuum drying oven at 75℃-85℃ for 10h-14h.

[0038] In one embodiment of the present invention: in step 4, the mass ratio of polycarbonate to dichloromethane is 1:8-12, and 4%-6% of allyl glycidyl ether by mass of polycarbonate and 0.4%-0.6% of azobisisobutyronitrile by mass of polycarbonate are slowly added as initiators while stirring, and the reaction is carried out in a constant temperature water bath at 55°C-65°C for 7h-9h. The solid obtained after filtration is dried in a vacuum drying oven at 75°C-85°C for 10h-14h.

[0039] In one embodiment of the present invention: in step five, the modified polycarbonate is added to the hopper of a twin-screw extruder and heated to a molten state. The temperature of zone one is set to 215°C-225°C, the temperature of zone two is set to 225°C-235°C, and the temperature of zone three is set to 235°C-245°C. Subsequently, a purified modifier accounting for 2%-4% of the mass of the modified polycarbonate is added, the screw speed is controlled at 180r / min-220r / min, and stirred for 12min-18min. Subsequently, the surface pretreated nano-titanium dioxide particles and the new coupling agent are uniformly mixed in a mass ratio of 8-12:1. The screw speed of the extruder is adjusted to 280r / min-320r / min, the residence time is 4min-6min, and after water-cooling, the strands are cut into particles with a particle size of 2.5mm-3.5mm using a pelletizer.

[0040] In one embodiment of the present invention, in step 1, during the ring-opening addition reaction, microwave-assisted heating is used to maintain the temperature gradient of the reaction system at ±5°C under a microwave power of 300 W, thereby promoting the reaction while suppressing the occurrence of side reactions, thereby improving the yield and purity of the new coupling agent, and by controlling the microwave frequency at 2.45 GHz, the molecular structure of the reaction product is made more regular, which is beneficial for subsequent combination with polycarbonate and nanoparticles, thereby further enhancing the interfacial compatibility.

[0041] In one embodiment of the present invention, in step 2, during the reaction process of grafting maleic anhydride onto the polyethylene glycol molecular chain, a synergistic catalyst can be added. The synergistic catalyst is aluminum trichloride, and the amount added is 1.5% of the mass of the polyethylene glycol. The synergistic catalyst can work together with dibenzoyl peroxide to reduce the reaction activation energy by 15 kJ / mol, accelerate the reaction rate, and at the same time make the molecular weight distribution of the grafted product more uniform, thereby making the performance of the new melt flow modifier more stable, the effect of reducing the melt viscosity of the polycarbonate more significantly, and better maintaining the fluidity of the system during subsequent processing.

[0042] In one embodiment of the present invention: in step three, when the surface of the nano-titanium dioxide particles is modified, two different modifiers can be introduced at the same time, one of which is 3-aminopropyltriethoxysilane and the other is hexadecyltrimethylammonium bromide, and the mass ratio of the two is 1:1. After adding 3-aminopropyltriethoxysilane and reacting for 2 hours, hexadecyltrimethylammonium bromide is added. Through the synergistic effect of the two modifiers, a composite functional group structure is formed on the surface of the nano-titanium dioxide particles, which not only enhances the interfacial bonding force between the nanoparticles and the polycarbonate, but also gives the composite material additional antistatic properties, thereby improving the comprehensive performance of the composite material.

[0043] In one embodiment of the present invention: in step 4, when allyl glycidyl ether and azobisisobutyronitrile are added to the polycarbonate solution for reaction, a stabilizer is added to the reaction system. The stabilizer is antioxidant 1010, and the added amount is 0.3% of the mass of the polycarbonate. This can prevent excessive cross-linking and degradation of the polycarbonate during the grafting reaction, ensure the introduction of a branched structure on the polycarbonate molecular chain, while maintaining the length and molecular weight of the polycarbonate molecular chain within a reasonable range, so that the modified polycarbonate has better flexibility and processing performance, thereby improving the mechanical properties and thermal stability of the final composite material.

[0044] In one embodiment of the present invention: acrylic acid ( ) and epichlorohydrin ( ) Ring-opening addition reaction catalyzed by tetrabutylammonium bromide:

[0045]

[0046] In one embodiment of the present invention: polyethylene glycol ( ) and maleic anhydride ( ) in dibenzoyl peroxide ( BPO ) to initiate the grafting reaction:

[0047]

[0048] Example 1, please refer to the attached Figure 1First, acrylic acid containing a carboxyl group and epichlorohydrin containing an epoxy group are selected and added to a reactor. Tetrabutylammonium bromide is added under nitrogen protection to carry out a ring-opening addition reaction. After the reaction is completed, the product is transferred to a separatory funnel and ether is added to extract according to a volume ratio of 1:3 between the product and ether. The organic phase is separated and the ether and unreacted raw materials are removed by vacuum distillation to obtain a high-purity new coupling agent. Then, polyethylene glycol with a molecular weight of 500 is used as the basic raw material. It is added to the reactor under nitrogen protection, and maleic anhydride is added. The molar ratio of polyethylene glycol to maleic anhydride is set to 1:1.3. The temperature is raised to 125°C, and dibenzoyl peroxide accounting for 1.2% of the total mass of the raw materials is added as an initiator. The reaction is carried out for 3.5 hours to make the maleic anhydride The anhydride was grafted onto the polyethylene glycol molecular chain to obtain a new melt flow modifier, and then the product was dissolved in chloroform at a mass ratio of 1:10 with chloroform, added dropwise to methanol for precipitation, filtered and dried in a vacuum drying oven at 65°C for 28 hours to obtain a purified modifier. Subsequently, the nano-titanium dioxide particles were dispersed in anhydrous ethanol at a mass ratio of 1:25, ultrasonically treated for 35 minutes to uniformly disperse, and 3-aminopropyltriethoxysilane accounting for 12% of the mass of the nanoparticles was added as a surface modifier. The reaction was stirred in an oil bath at 65°C for 4.5 hours to introduce amino functional groups on the surface of the nanoparticles. After the reaction was completed, the mixture was centrifuged at 6000r / min for 15 minutes, washed 4 times with anhydrous ethanol, and dried at 85°C. The mixture was dried in a vacuum drying oven for 14 hours to obtain surface pretreated nano-titanium dioxide particles. After that, the polycarbonate was dissolved in dichloromethane at a mass ratio of 1:12, and allyl glycidyl ether accounting for 6% of the mass of the polycarbonate and azobisisobutyronitrile accounting for 0.6% of the mass of the polycarbonate were slowly added as initiators while stirring. The mixture was reacted in a constant temperature water bath at 65°C for 9 hours to graft allyl glycidyl ether with the polycarbonate molecular chain and introduce a branched structure. After the reaction, sufficient methanol was poured into the mixture for precipitation. After filtration, the mixture was dried in a vacuum drying oven at 85°C for 14 hours to obtain the modified polycarbonate. Finally, the modified polycarbonate was added to the hopper of the twin-screw extruder. The temperature of zone 1 was set to 225°C and the temperature of zone 2 was set to 235°C. The temperature of the third zone is set to 245°C, and a purified modifier accounting for 4% of the mass of the modified polycarbonate is added. The screw speed is controlled at 220r / min and stirred for 18 minutes to fully disperse the modifier. The surface pretreated nano-titanium dioxide particles and the new coupling agent are then mixed evenly in a mass ratio of 12:1. The nano-titanium dioxide particles are added to the twin-screw extruder through a side feeding device and fully mixed with the molten polycarbonate. The screw speed of the extruder is adjusted to 320r / min and the residence time is 6 minutes. The coupling agent reacts chemically between the nano-particles and the polycarbonate to form a good interface bond. The extruded material is water-cooled and drawn into strips, and then cut into particles with a particle size of 3.5mm by a pelletizer to obtain a high-transmittance polycarbonate nanoparticle composite material.

[0049] Example 2, please refer to the attached Figure 1First, select acrylic acid containing carboxyl groups and epichlorohydrin containing epoxy groups, add them to the reactor, add tetrabutylammonium bromide under nitrogen protection, and carry out ring-opening addition reaction. After the reaction is completed, transfer the product to a separatory funnel, add ether according to the product and ether volume ratio of 1:2 for extraction, separate the organic phase, remove the ether and unreacted raw materials by vacuum distillation, and obtain a high-purity new coupling agent. Then, take polyethylene glycol with a molecular weight of 300 as the basic raw material, add it to the reactor under nitrogen protection, and then add maleic anhydride, the molar ratio of polyethylene glycol to maleic anhydride is set to 1:1.1, heat to 115 ° C, add dibenzoyl peroxide as an initiator accounting for 0.8% of the total mass of the raw materials, react for 2.5 hours, and make Maleic anhydride was grafted onto the polyethylene glycol molecular chain to obtain a new melt flow modifier, and then the product was dissolved in chloroform at a mass ratio of 1:5 with chloroform, added dropwise to methanol for precipitation, filtered and dried in a vacuum drying oven at 55°C for 20 hours to obtain a purified modifier. Subsequently, nano-titanium dioxide particles were dispersed in anhydrous ethanol at a mass ratio of 1:15, ultrasonically treated for 25 minutes to uniformly disperse, and 3-aminopropyltriethoxysilane accounting for 8% of the mass of the nanoparticles was added as a surface modifier. The reaction was stirred in an oil bath at 55°C for 3.5 hours to introduce amino functional groups on the surface of the nanoparticles. After the reaction was completed, the mixture was centrifuged at 4000r / min for 10 minutes, washed twice with anhydrous ethanol, and dried at 75°C. The mixture was dried in a vacuum drying oven for 10 hours to obtain surface pretreated nano-titanium dioxide particles. After that, the polycarbonate was dissolved in dichloromethane at a mass ratio of 1:8, and allyl glycidyl ether accounting for 4% of the mass of the polycarbonate and azobisisobutyronitrile accounting for 0.4% of the mass of the polycarbonate were slowly added as initiators while stirring. The mixture was reacted in a constant temperature water bath at 55°C for 7 hours to graft allyl glycidyl ether with the polycarbonate molecular chain and introduce a branched structure. After the reaction, sufficient methanol was poured into the mixture for precipitation. After filtration, the mixture was dried in a vacuum drying oven at 75°C for 10 hours to obtain the modified polycarbonate. Finally, the modified polycarbonate was added to the hopper of the twin-screw extruder. The temperature of zone 1 was set to 215°C and the temperature of zone 2 was set to 225°C. The temperature of the third zone is set to 235°C, and a purified modifier accounting for 2% of the mass of the modified polycarbonate is added. The screw speed is controlled at 180r / min and stirred for 12 minutes to fully disperse the modifier. The surface pretreated nano-titanium dioxide particles and the new coupling agent are then mixed evenly in a mass ratio of 8:1. The nano-titanium dioxide particles are added to the twin-screw extruder through a side feeding device and fully mixed with the molten polycarbonate. The screw speed of the extruder is adjusted to 280r / min and the residence time is 4 minutes. The coupling agent reacts chemically between the nano-particles and the polycarbonate to form a good interface bond. The extruded material is water-cooled and drawn into strips, and then cut into particles with a particle size of 2.5mm by a pelletizer to obtain a high-transmittance polycarbonate nanoparticle composite material.

[0050] According to the above two groups of examples, it can be concluded that by selecting acrylic acid and epichlorohydrin to prepare a new coupling agent, introducing maleic anhydride based on polyethylene glycol to prepare a new melt flow modifier, and pre-modifying polycarbonate, a series of operations can effectively improve the interfacial compatibility of the polycarbonate nanoparticle composite material, reduce the melt viscosity of the system, and enhance the mechanical properties and processing fluidity of the material. In addition, with the help of the coordinated cooperation of multiple technologies in each link, a polycarbonate nanoparticle composite material product with high light transmittance can be prepared. While maintaining high light transmittance, the problem of high melt viscosity is overcome, the molding difficulty is reduced, and product defects are reduced. The present invention has significant technical advantages and broad application prospects.

[0051] Although the present invention is disclosed above with reference to preferred embodiments, this is not intended to limit the present invention. Any person skilled in the art may make possible changes and modifications without departing from the spirit and scope of the present invention. Therefore, any modifications, equivalent variations, and modifications made to the above embodiments in accordance with the technical essence of the present invention without departing from the content of the technical solution of the present invention shall fall within the scope of protection defined by the claims of the present invention.

Claims

1. Preparation of high-transmittance polycarbonate nanoparticle composite material, including a preparation process, characterized in that: The preparation process includes the following specific steps: Step 1: Selecting acrylic acid containing a carboxyl group and epichlorohydrin containing an epoxy group as raw materials, adding the raw materials to a reactor, adding tetrabutylammonium bromide under nitrogen protection to carry out a ring-opening addition reaction, after the reaction is completed, transferring the product to a separatory funnel for extraction, separating the organic phase, and then removing ether and unreacted raw materials by reduced pressure distillation to obtain a high-purity new coupling agent; Step 2: Using polyethylene glycol as the base raw material, polyethylene glycol is added to a reactor under nitrogen protection, maleic anhydride is added to the reactor to react, and then dibenzoyl peroxide is added as an initiator to react again. After the reaction is completed, the product is dissolved in chloroform and then added dropwise to methanol for precipitation. After filtering and drying, a purified modifier is obtained; Step 3: Dispersing the nano-titanium dioxide particles in anhydrous ethanol and performing ultrasonic treatment, then adding 3-aminopropyltriethoxysilane as a surface modifier, stirring and reacting in an oil bath, and after the reaction is completed, transferring the mixed solution to a centrifuge tube and centrifuging, then washing the product with anhydrous ethanol and drying it to obtain surface-pretreated nano-titanium dioxide particles for later use; Step 4: dissolving the polycarbonate in dichloromethane, slowly adding allyl glycidyl ether and azobisisobutyronitrile as initiators while stirring, and reacting in a constant temperature water bath. After the reaction is completed, pouring the reaction solution into a sufficient amount of methanol for precipitation, filtering the obtained solid and drying it in a vacuum drying oven to obtain the modified polycarbonate; Step 5: Add the modified polycarbonate to the hopper of a twin-screw extruder and heat it to a molten state. Then, add the purified modifier and stir it. Then, mix the surface-pretreated nano-titanium dioxide particles and the new coupling agent evenly. Then, add it to the twin-screw extruder through a side feeding device and fully mix it with the molten polycarbonate. After the extruded material is water-cooled and stretched, it is cut into particles by a pelletizer to obtain a high-transmittance polycarbonate nanoparticle composite material.

2. The preparation of the high-transmittance polycarbonate nanoparticle composite material according to claim 1, characterized in that: In the step 1, acrylic acid and epichlorohydrin are added to a reactor in a molar ratio of 1.5-2.5:1, and tetrabutylammonium bromide is added as a catalyst in an amount of 2%-4% by weight of the total raw materials. The reaction temperature is controlled at 75° C.-85° C., and the reaction time is controlled at 5 h-7 h.

3. The preparation of the high-transmittance polycarbonate nanoparticle composite material according to claim 1, characterized in that: In the step 1, after the reaction is completed, the product is transferred to a separatory funnel, and ether is added in a volume ratio of 1:2-3 between the product and ether for extraction.

4. The preparation of the high-transmittance polycarbonate nanoparticle composite material according to claim 1, characterized in that: In the step 2, the molecular weight of the basic raw material polyethylene glycol is 300-500, and the molar ratio of polyethylene glycol to maleic anhydride is 1:1.1-1.

3. Subsequently, the reactor is heated to 115°C-125°C, and 0.8%-1.2% of the total mass of the raw materials is added as an initiator. The reaction is carried out for 2.5h-3.5h to graft the maleic anhydride onto the polyethylene glycol molecular chain to obtain a new melt flow modifier.

5. The preparation of the high-transmittance polycarbonate nanoparticle composite material according to claim 1, characterized in that: In the step 2, when the product is dissolved in chloroform, chloroform is added according to a mass ratio of product to chloroform of 1:5-10, and then added dropwise into methanol for precipitation. After filtering, the mixture is dried in a vacuum drying oven at 55°C-65°C for 20h-28h.

6. The preparation of the high-transmittance polycarbonate nanoparticle composite material according to claim 1, characterized in that: In the step three, the nano-titanium dioxide particles are dispersed in anhydrous ethanol at a mass ratio of the nano-titanium dioxide particles to the ethanol of 1:15-25, and ultrasonic treatment is performed for 25-35 minutes. Subsequently, 3-aminopropyltriethoxysilane accounting for 8%-12% of the mass of the nanoparticles is added as a surface modifier, and the reaction is stirred in an oil bath at 55°C-65°C for 3.5-4.5 hours.

7. The preparation of the high-transmittance polycarbonate nanoparticle composite material according to claim 1, characterized in that: In the step 3, the centrifuge tube is centrifuged at a speed of 4000 r / min-6000 r / min for 10 min-15 min, and then the product is washed with anhydrous ethanol 2-4 times and dried in a vacuum drying oven at 75° C.-85° C. for 10 h-14 h.

8. The preparation of the high-transmittance polycarbonate nanoparticle composite material according to claim 1, characterized in that: In the step 4, the mass ratio of polycarbonate to dichloromethane is 1:8-12, and 4%-6% of allyl glycidyl ether by mass of the polycarbonate and 0.4%-0.6% of azobisisobutyronitrile by mass of the polycarbonate are slowly added as initiators while stirring, and the mixture is reacted in a constant temperature water bath at 55°C-65°C for 7h-9h. The solid obtained after filtration is dried in a vacuum drying oven at 75°C-85°C for 10h-14h.

9. The preparation of the high-transmittance polycarbonate nanoparticle composite material according to claim 1, characterized in that: In the step 5, the modified polycarbonate is added to the hopper of the twin-screw extruder and heated to a molten state. The temperature of zone 1 is set to 215°C-225°C, the temperature of zone 2 is set to 225°C-235°C, and the temperature of zone 3 is set to 235°C-245°C. Subsequently, a purified modifier accounting for 2%-4% of the mass of the modified polycarbonate is added, the screw speed is controlled at 180r / min-220r / min, and stirred for 12min-18min. Subsequently, the surface pretreated nano-titanium dioxide particles and the new coupling agent are uniformly mixed in a mass ratio of 8-12:

1. The screw speed of the extruder is adjusted to 280r / min-320r / min, the residence time is 4min-6min, and after water-cooling, the strands are cut into particles with a particle size of 2.5mm-3.5mm using a pelletizer.

10. Use of the high-transmittance polycarbonate nanoparticle composite material according to any one of claims 1 to 9, characterized in that: High-transmittance polycarbonate nanoparticle composites are used in optical displays, automotive manufacturing, construction, medical devices and aerospace.

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