A high heat-resistant PBT foam diffusion plate and preparation method thereof

Abstract

The invention discloses a high-heat-resistant PBT foamed diffuser plate and a preparation method thereof. The high-heat-resistant PBT foamed diffuser plate comprises the following components by weight, namely, PBT resin, PMMA-PEI polymer microspheres, silane coupling agent, sodium citrate, anhydrous ethanol, antioxidant, ultraviolet absorber, light stabilizer, mineral oil, brightener, flame retardant and foaming agent. PBT resin is selected as a diffuser plate substrate to ensure that the diffuser plate has relatively high heat resistance. Meanwhile, a new PMMA-PEI polymer microsphere is provided as a light diffuser, so that the prepared diffuser plate can obtain high light transmittance and haze while greatly improving the heat resistance of the diffuser plate. Sodium citrate and silane coupling agent can be added to enhance the interface compatibility of PMMA-PEI polymer microspheres and PBT resin substrates. A small amount of mineral oil is added to make the PMMA-PEI polymer microspheres disperse more evenly in the system. The diffuser plate prepared by the above formula has high heat resistance and good optical properties.

Description

Technical Field

[0001] The invention relates to the technical field of diffusion plates, in particular to a high-heat-resistant PBT foamed diffusion plate and a preparation method thereof. Background Art

[0002] Diffusers are widely used in liquid crystal display, LED lighting and imaging systems. Their main function is to fully scatter the incident light to achieve a softer and more uniform illumination effect. However, the existing GPPS materials used to manufacture optical diffusers generally have poor heat resistance and impact resistance. After long-term use, the heat of the light source can easily cause the diffuser to deform, affecting its service life. During transportation, it is easy to be damaged by impact, resulting in defects.

[0003] Polybutylene terephthalate (PBT resin for short) is a linear saturated polyester, mainly formed by polycondensation of terephthalic acid and 1,4-butanediol, with terminal groups of hydroxyl and carboxyl. Since its main chain is a linear thermoplastic saturated polyester with an ester bond, it has a high melting point and crystallinity, relatively low water absorption and thermal expansion coefficient, high strength, and good fatigue resistance. In addition, it also has excellent long-term chemical resistance. At room temperature, except for strong alkaline liquids, there is almost no performance degradation after long-term immersion in them. It has no stress cracking, is not easy to decompose in water, has good heat aging resistance, and has the potential to be used as a diffuser plate substrate. However, no relevant reports on the application of PBT resin in the field of light diffuser plate technology have been found so far. Our research found that if PBT resin is simply used to replace GPPS resin, the light diffusion effect of the diffuser plate is very poor. This may be due to the following two reasons. First, the refractive index of PBT resin as the base material does not match that of existing light diffusers such as glass microspheres, resulting in poor light diffusion effect. Second, the existing light diffusers are not compatible with PBT resin, which causes the existing light diffusers to aggregate and distribute unevenly, resulting in poor light diffusion effect. Summary of the invention

[0004] In order to solve the above problems, one of the purposes of this application is achieved by adopting the following technical solution:

[0005] A high heat-resistant PBT foamed diffusion plate comprises the following components by weight: 20-50 parts of PBT resin, 9-18 parts of PMMA-PEI polymer microspheres, 2-6 parts of silane coupling agents, 1-3 parts of sodium citrate, 30-40 parts of anhydrous ethanol, 0.7-1.3 parts of antioxidants, 0.4-0.8 parts of ultraviolet absorbers, 0.5-0.9 parts of light stabilizers, 0.15-0.45 parts of mineral oils, 0.05-0.15 parts of brighteners, 6-8 parts of flame retardants, and 0.2-1.4 parts of foaming agents.

[0006] Preferably, the method for preparing PMMA-PEI polymer microspheres comprises the following steps:

[0007] Add 1 to 5 parts of MMA to 12 to 20 parts of deionized water at 340 to 380 m 3 / h flow rate of nitrogen, stirring at a speed of 300-600r / min; expelling oxygen for 1-3h, turning off the nitrogen; adding 0.06-0.18 parts of initiator 2,2-azobis(2-methylpropylimidamide) dihydrochloride, and polymerizing at a constant temperature for 1-3h; after the reaction is completed, cooling to room temperature to obtain PMMA microspheres;

[0008] Disperse 30-60 parts of the above PMMA microspheres and 5-15 parts of sodium citrate in 80-120 parts of distilled water, add 10-30 parts of polyethyleneimine while stirring at 100-300 r / min, ultrasonically disperse for 30-60 minutes, centrifuge at 5000-10000 r / min to discard the supernatant, add distilled water to wash 2-4 times, and dry at 40-60°C for 12-24 hours to obtain PMMA-PEI polymer microspheres. By introducing carboxyl groups on PMMA microspheres to react with the amine groups of polyethyleneimine to form amide bonds with high chemical stability, PEI is firmly coated on the surface of PMMA microspheres.

[0009] Preferably, the polymerization temperature is kept constant at 60°C.

[0010] Preferably, the silane coupling agent is an aminosilane coupling agent or an epoxysilane coupling agent.

[0011] Preferably, the antioxidant is any one of antioxidant 1024, antioxidant 1010 or antioxidant 1076.

[0012] Preferably, the ultraviolet absorber is selected from any one of ultraviolet absorbers UV-327, UV-329, and UV-531.

[0013] Preferably, the light stabilizer is selected from any one of light stabilizer 770, light stabilizer 944 or light stabilizer 622.

[0014] Preferably, the foaming agent is sodium bicarbonate. Compared with other types of foaming agents, sodium bicarbonate can begin to decompose at a lower temperature. The carbon dioxide gas released during the heating process can form tiny bubbles inside the diffuser plate, thereby improving the light scattering effect of the diffuser plate.

[0015] Preferably, the flame retardant is melamine. Compared with other types of flame retardants, melamine can work synergistically with PBT resin, not only making the diffuser plate flame retardant, but also significantly improving the heat resistance of the diffuser plate.

[0016] The second purpose of this application is achieved by the following technical solution:

[0017] The method for preparing the high heat-resistant PBT foamed diffuser plate is characterized in that it comprises the following steps: adding the above-mentioned parts by weight of anhydrous ethanol, PMMA-PEI polymer microspheres, sodium citrate, and silane coupling agent into a container, stirring for 20 to 40 minutes at 40 to 60° C. to obtain a mixture a, then adding the above-mentioned parts by weight of PBT resin, antioxidant, ultraviolet absorber, light stabilizer, mineral oil, brightener, flame retardant, and foaming agent into the mixture a, stirring evenly at a speed of 400 to 600 r / min, and finally putting it into a single-screw extruder for heating, melting, and extruding to obtain a high heat-resistant PBT foamed diffuser plate;

[0018] Among them, the temperatures of each zone of the single-screw extruder are: zone one temperature is 180-190°C, zone two temperature is 190-200°C, zone three temperature is 210-220°C, zone four temperature is 210-220°C, zone five temperature is 225-235°C, zone six temperature is 215-225°C, zone seven temperature is 210-220°C, die head temperature is 205-215°C, and the production speed is 320Kg / h.

[0019] The beneficial effects are as follows: the present application selects PBT resin as the diffusion plate substrate to ensure that the diffusion plate has a relatively high heat resistance, and at the same time provides a new PMMA-PEI polymer microsphere as a light diffuser. The refractive index of this special light diffuser is 1.5479, which is slightly different from the refractive index of PBT 1.5812. Therefore, the prepared diffusion plate can obtain a higher light transmittance and haze while also greatly improving the heat resistance of the diffusion plate. In order to improve the interface interaction between the PMMA-PEI polymer microsphere and the PBT resin substrate, the present application, on the one hand, adds sodium citrate to the formula to chemically graft the PMMA-PEI polymer microsphere, introduces carboxyl groups on the surface of the PMMA-PEI polymer microspheres to react with the hydroxyl groups of the PBT resin at high temperature to form ester bonds, and the PEI The amine group can also react with the carboxyl group in the PBT resin to form an amide bond through an amidation reaction; on the other hand, the compatibility between the PMMA-PEI polymer microspheres and the PBT resin substrate is promoted by adding a silane coupling agent containing an amino group or an epoxy group. One end of the silane coupling agent containing an amino group or an epoxy group reacts with the surface of the PMMA-PEI polymer microspheres to form a coupling agent layer, and the other end reacts with the carboxyl group or hydroxyl group of the PBT resin, thereby building a bridge between the PMMA-PEI polymer microspheres and the PBT resin, improving the interfacial compatibility between the two, and forming a stable and uniform system; finally, a small amount of mineral oil is added to make the PMMA-PEI polymer microspheres more evenly dispersed in the system, so that the light scattering is more even. The diffuser plate prepared by the formula of the present invention is not only highly heat-resistant but also has good optical properties. DETAILED DESCRIPTION

[0020] The present invention is further described in detail below in conjunction with specific embodiments so that those skilled in the art can understand the present invention more clearly.

[0021] The following embodiments are only used to illustrate the present invention, but are not limited to the scope of the present invention. Based on the specific embodiments of the present invention, all other embodiments obtained by ordinary technicians in the field without creative work belong to the protection scope of the present invention.

[0022] In the examples of the present invention, unless otherwise specified, all raw material components are commercially available products well known to those skilled in the art; in the examples of the present invention, unless otherwise specified, the technical means used are conventional means well known to those skilled in the art.

[0023] Source of raw materials:

[0024] PBT resin, purchased from Suzhou Xindezhi New Materials Co., Ltd.;

[0025] Methyl methacrylate (MMA) and 2,2-azobis(2-methylpropylimidamide) dihydrochloride were purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0026] Polyethyleneimine (PEI), Ultem 1000, was purchased from Saudi Basic Industries Corporation;

[0027] Sodium citrate was purchased from Shandong Gushuo Biotechnology Co., Ltd.;

[0028] Aminosilane coupling agent, purchased from Changsha Zhongyi Chemical Co., Ltd.;

[0029] Epoxy silane coupling agent, purchased from Shandong Yuanjin New Materials Co., Ltd.;

[0030] Anhydrous ethanol was purchased from Guangdong Wengjiang Chemical Reagent Co., Ltd.;

[0031] Antioxidants were purchased from Shandong Xuxiang Chemical Co., Ltd.

[0032] Ultraviolet absorber, purchased from Jinan Xiangfeng Weiye Chemical Co., Ltd.;

[0033] Light stabilizer, purchased from Shanghai Tiandui New Materials Co., Ltd.;

[0034] Mineral oil was purchased from Jinan Xuchuang Chemical Technology Co., Ltd.

[0035] Brightening agent, purchased from Guangzhou Yuanda New Materials Co., Ltd.;

[0036] Melamine, purchased from Qidong Rongsheng Chemical Co., Ltd.;

[0037] Sodium bicarbonate was purchased from Shandong Haihua New Materials Co., Ltd.;

[0038] The remaining reagents are commercially available.

[0039] Example 1

[0040] The present embodiment provides a high heat-resistant PBT foam diffuser plate, which includes the following components by weight: 35 parts of PBT resin, 13.5 parts of PMMA-PEI polymer microspheres, 4 parts of silane coupling agent, 2 parts of sodium citrate, 35 parts of anhydrous ethanol, 1 part of antioxidant, 0.6 parts of ultraviolet absorber, 0.7 parts of light stabilizer, 0.3 parts of mineral oil, 0.1 parts of brightener, 7 parts of flame retardant, and 0.8 parts of foaming agent;

[0041] The silane coupling agent is aminosilane coupling agent, the antioxidant is antioxidant 1024, the ultraviolet absorber is ultraviolet absorber UV-327, the light stabilizer is light stabilizer 770, the flame retardant is melamine, and the foaming agent is sodium bicarbonate;

[0042] The method for preparing the high heat-resistant PBT foaming diffusion plate comprises the following steps:

[0043] To prepare PMMA-PEI polymer microspheres, 3 parts of MMA were added to 16 parts of deionized water and the mixture was stirred at 360 mL. 3 / h flow rate of nitrogen, stirring at a speed of 450r / min; expel oxygen for 2h, turn off nitrogen; add 0.12 parts of initiator 2,2-azobis(2-methylpropylimidazole) dihydrochloride, keep the temperature at 60°C for polymerization for 2h; after the reaction is completed, cool to room temperature to obtain PMMA microspheres; disperse 45 parts of the PMMA microspheres and 10 parts of sodium citrate in 100 parts of distilled water, add 20 parts of polyethyleneimine while stirring at a speed of 200r / min, ultrasonically disperse for 45min, centrifuge at 7500r / min to discard the supernatant, add distilled water to wash 3 times, and dry at 50°C for 18h to obtain the PMMA-PEI polymer microspheres;

[0044] Add the above-mentioned parts by weight of anhydrous ethanol, PMMA-PEI polymer microspheres, sodium citrate, and silane coupling agent into a container, stir at 50° C. for 30 minutes to obtain a mixture a, then add the above-mentioned parts by weight of PBT resin, antioxidant, ultraviolet absorber, light stabilizer, mineral oil, brightener, flame retardant, and foaming agent into the mixture a, stir evenly at a speed of 500 r / min, and finally put into a single-screw extruder to heat, melt, and extrude to obtain a high heat-resistant PBT foamed diffusion plate;

[0045] Among them, the temperatures of each zone of the single-screw extruder are: zone 1 temperature is 185°C, zone 2 temperature is 195°C, zone 3 temperature is 215°C, zone 4 temperature is 215°C, zone 5 temperature is 230°C, zone 6 temperature is 220°C, zone 7 temperature is 215°C, and the die head temperature is 210°C.

[0046] Example 2

[0047] The present embodiment provides a high heat-resistant PBT foam diffuser plate, which includes the following components by weight: 50 parts of PBT resin, 9 parts of PMMA-PEI polymer microspheres, 2 parts of silane coupling agent, 1 part of sodium citrate, 30 parts of anhydrous ethanol, 0.7 parts of antioxidant, 0.4 parts of ultraviolet absorber, 0.5 parts of light stabilizer, 0.15 parts of mineral oil, 0.05 parts of brightener, 6 parts of flame retardant, and 0.2 parts of foaming agent;

[0048] The silane coupling agent is epoxy silane coupling agent, the antioxidant is antioxidant 1010, the ultraviolet absorber is ultraviolet absorber UV-329, the light stabilizer is light stabilizer 944, the flame retardant is aluminum hydroxide, and the foaming agent is sodium bicarbonate;

[0049] The method for preparing the high heat-resistant PBT foaming diffusion plate comprises the following steps:

[0050] To prepare PMMA-PEI polymer microspheres, 1 part MMA was added to 20 parts of deionized water at 340 m 3 / h flow rate of nitrogen, stirring at a speed of 300r / min; expel oxygen for 1h, turn off nitrogen; add 0.06 parts of initiator 2,2-azobis(2-methylpropylimidazole) dihydrochloride, keep the temperature at 60°C for polymerization for 1h; after the reaction is completed, cool to room temperature to obtain PMMA microspheres; disperse 30 parts of the PMMA microspheres and 15 parts of sodium citrate in 120 parts of distilled water, add 10 parts of polyethyleneimine while stirring at a speed of 100r / min, ultrasonically disperse for 30min, centrifuge at 5000r / min to discard the supernatant, add distilled water to wash twice, and dry at 40°C for 12h to obtain the PMMA-PEI polymer microspheres;

[0051] Add the above-mentioned parts by weight of anhydrous ethanol, PMMA-PEI polymer microspheres, sodium citrate, and silane coupling agent into a container, stir at 60° C. for 40 minutes to obtain a mixture a, then add the above-mentioned parts by weight of PBT resin, antioxidant, ultraviolet absorber, light stabilizer, mineral oil, brightener, flame retardant, and foaming agent into the mixture a, stir evenly at a speed of 600 r / min, and finally put into a single-screw extruder to heat, melt, and extrude to obtain a high heat-resistant PBT foamed diffuser plate;

[0052] Among them, the temperatures of each zone of the single-screw extruder are: zone 1 temperature is 180°C, zone 2 temperature is 190°C, zone 3 temperature is 210°C, zone 4 temperature is 210°C, zone 5 temperature is 225°C, zone 6 temperature is 215°C, zone 7 temperature is 210°C, and the die head temperature is 205°C.

[0053] Example 3

[0054] The present embodiment provides a high heat-resistant PBT foam diffusion plate, which includes the following components by weight: 20 parts of PBT resin, 18 parts of PMMA-PEI polymer microspheres, 6 parts of silane coupling agent, 3 parts of sodium citrate, 40 parts of anhydrous ethanol, 1.3 parts of antioxidant, 0.8 parts of ultraviolet absorber, 0.9 parts of light stabilizer, 0.45 parts of mineral oil, 0.15 parts of brightener, 8 parts of flame retardant, and 1.4 parts of foaming agent;

[0055] The silane coupling agent is aminosilane coupling agent, the antioxidant is antioxidant 1076, the ultraviolet absorber is ultraviolet absorber UV-531, the light stabilizer is light stabilizer 622, the flame retardant is tetrabromobisphenol A, and the foaming agent is sodium bicarbonate;

[0056] The method for preparing the high heat-resistant PBT foaming diffusion plate comprises the following steps:

[0057] To prepare PMMA-PEI polymer microspheres, 5 parts of MMA were added to 12 parts of deionized water and the mixture was stirred at 380 mL. 3 / h flow rate of nitrogen, stirring at a speed of 600r / min; expel oxygen for 3h, turn off nitrogen; add 0.18 parts of initiator 2,2-azobis(2-methylpropylimidazole) dihydrochloride, keep the temperature at 60°C for polymerization for 3h; after the reaction is completed, cool to room temperature to obtain PMMA microspheres; disperse 60 parts of the PMMA microspheres and 5 parts of sodium citrate in 80 parts of distilled water, add 30 parts of polyethyleneimine while stirring at a speed of 300r / min, ultrasonically disperse for 60min, centrifuge at 10000r / min to discard the supernatant, add distilled water to wash 4 times, and dry at 60°C for 24h to obtain the PMMA-PEI polymer microspheres;

[0058] Add the above-mentioned parts by weight of anhydrous ethanol, PMMA-PEI polymer microspheres, sodium citrate, and silane coupling agent into a container, stir at 40° C. for 20 minutes to obtain a mixture a, then add the above-mentioned parts by weight of PBT resin, antioxidant, ultraviolet absorber, light stabilizer, mineral oil, brightener, flame retardant, and foaming agent into the mixture a, stir evenly at a speed of 400 r / min, and finally put into a single-screw extruder to heat, melt, and extrude to obtain a high heat-resistant PBT foamed diffuser plate;

[0059] Among them, the temperatures of each zone of the single-screw extruder are: zone 1 temperature is 190°C, zone 2 temperature is 200°C, zone 3 temperature is 220°C, zone 4 temperature is 220°C, zone 5 temperature is 235°C, zone 6 temperature is 225°C, zone 7 temperature is 220°C, and the die head temperature is 215°C.

[0060] Comparative Example 1

[0061] The difference between this comparative example and Example 1 is that 35 parts of PBT resin in Example 1 are replaced by 35 parts of GPPS, and the other components and experimental steps are the same as those in Example 1.

[0062] Comparative Example 2

[0063] The difference between this comparative example and Example 1 is that 13.5 parts of glass microspheres are used to replace 13.5 parts of PMMA-PEI polymer microspheres in Example 1, and the other components and experimental steps are the same as those in Example 1.

[0064] Comparative Example 3

[0065] The difference between this comparative example and Example 1 is that the amount of PBT resin is increased from 35 parts to 41 parts, and aminosilane coupling agent and sodium citrate are not added. The other components and experimental steps are the same as those in Example 1.

[0066] Comparative Example 4

[0067] The difference between this comparative example and Example 1 is that the amount of PBT resin is increased from 35 parts to 35.3 parts, and mineral oil is not added. The other components and experimental steps are the same as those in Example 1.

[0068] The diffuser plates prepared in Examples 1 to 3 and Comparative Examples 1 to 4 were tested.

[0069] Test method:

[0070] Heat deformation temperature is tested according to ASTM D648 standard;

[0071] Impact strength is tested according to ASTM D256 standard;

[0072] Flame retardancy is tested according to UL94 standard;

[0073] Light transmittance and haze are tested according to ASTM D1003 standard;

[0074] Density is tested according to ASTM D792;

[0075] The center brightness and average brightness were tested according to GY / T 326-2019 standard, and the test results are shown in Table 1.

[0076] Table 1 Diffuser plate performance test results

[0077]

[0078]

[0079] From the above experimental data, the various performance indicators in Examples 1 to 3 are better than those in the comparative example, and the heat deformation temperature, impact strength, light transmittance and haze indicators in Example 1 are better than those in Examples 2 and 3. This may be related to the fact that melamine is not selected as the flame retardant. Melamine and PBT resin work synergistically, which can not only make the diffuser plate flame retardant, but also improve the heat resistance of the diffuser plate.

[0080] By comparing the data of Example 1 with those of the four comparative examples, it is found that the heat deformation temperature and impact strength data of the diffuser prepared by using PBT resin in Example 1 are greatly improved compared with those prepared by using GPPS in Comparative Example 1, which indicates that the use of PBT material to prepare the diffuser in the present application helps to improve the heat resistance and impact resistance of the diffuser; compared with Comparative Example 2, it can be found that after using glass microspheres to replace PMMA-PEI polymer microspheres, the light transmittance and haze of the diffuser are very poor, which may be due to the large difference in refractive index between the glass microspheres used as light diffusers and the PBT resin substrate, resulting in the diffusion; at the same time, it is also found that the heat deformation temperature and impact strength of Comparative Example 2 are not as good as those of Example 1, which indicates that the PMMA-PEI polymer provided in the present application The microspheres and the PBT resin act synergistically to improve the heat resistance and impact strength of the diffuser plate. Compared with Comparative Example 3, Example 1 shows that after the aminosilane coupling agent and sodium citrate are not added, the light transmittance, haze, center brightness and average brightness of the diffuser plate are all deteriorated. This may be because the lack of aminosilane coupling agent and sodium citrate deteriorates the interface compatibility between PMMA-PEI polymer microspheres and PBT resin substrate, and fails to form a stable and uniform system. Compared with Comparative Example 4, Example 1 shows that after the mineral oil is not added, the light transmittance, haze, center brightness and average brightness of the diffuser plate are also deteriorated, indicating that adding a small amount of mineral oil may help PMMA-PEI polymer microspheres to be more evenly dispersed in the system, which can improve the optical properties of the diffuser plate.

[0081] In summary, the present application selects PBT resin as the diffuser plate substrate to ensure that the diffuser plate has a relatively high heat resistance, and at the same time provides a new PMMA-PEI polymer microsphere as a light diffuser. The refractive index of this special light diffuser is 1.5479, which is slightly different from the refractive index of PBT 1.5812. Therefore, the prepared diffuser plate can obtain a higher transmittance and haze while also greatly improving the heat resistance of the diffuser plate. In order to improve the interface interaction between the PMMA-PEI polymer microsphere and the PBT resin substrate, the present application, on the one hand, adds sodium citrate to the formula to chemically graft the PMMA-PEI polymer microsphere, introduces carboxyl groups on the surface of the PMMA-PEI polymer microspheres to react with the hydroxyl groups of the PBT resin at high temperature to form ester bonds, and the amines in PEI The group can also form an amide bond with the carboxyl group in the PBT resin through an amidation reaction; on the other hand, the compatibility between the PMMA-PEI polymer microspheres and the PBT resin substrate is promoted by adding a silane coupling agent containing an amino group or an epoxy group. One end of the silane coupling agent containing an amino group or an epoxy group reacts with the surface of the PMMA-PEI polymer microspheres to form a coupling agent layer, and the other end reacts with the carboxyl group or hydroxyl group of the PBT resin, thereby building a bridge between the PMMA-PEI polymer microspheres and the PBT resin, improving the interfacial compatibility between the two, and forming a stable and uniform system; finally, by adding a small amount of mineral oil, the PMMA-PEI polymer microspheres are dispersed more evenly in the system, making the light scattering more evenly. The diffuser plate prepared by the formula of the present application is not only highly heat-resistant but also has good optical properties.

[0082] The above is only an embodiment of the present invention and is not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent substitution, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of the claims of the present invention.

Claims

1. A high heat-resistant PBT foam diffuser plate, characterized in that: The following components are included in parts by weight: 20-50 parts of PBT resin, 9-18 parts of PMMA-PEI polymer microspheres, 2-6 parts of silane coupling agent, 1-3 parts of sodium citrate, 30-40 parts of anhydrous ethanol, 0.7-1.3 parts of antioxidant, 0.4-0.8 parts of ultraviolet absorber, 0.5-0.9 parts of light stabilizer 770 or light stabilizer 944 or light stabilizer 622, 0.15-0.45 parts of mineral oil, 0.05-0.15 parts of brightener, 6-8 parts of flame retardant, and 0.2-1.4 parts of foaming agent; The method for preparing PMMA-PEI polymer microspheres comprises the following steps: Add 1-5 parts of MMA to 12-20 parts of deionized water at 340-380 m 3 / h flow rate of nitrogen, stirring at 300-600r / min; expelling oxygen for 1-3 h, and then turning off the nitrogen; adding 0.06-0.18 parts of initiator 2,2-azobis(2-methylpropylimidamide) dihydrochloride, and polymerizing at a constant temperature for 1-3 h; after the reaction, cooling to room temperature to obtain PMMA microspheres; Disperse 30-60 parts of the PMMA microspheres and 5-15 parts of sodium citrate in 80-120 parts of distilled water, add 10-30 parts of polyethyleneimine while stirring at a speed of 100-300 r / min, ultrasonically disperse for 30-60 min, centrifuge at 5000-10000 r / min to discard the supernatant, add distilled water to wash 2-4 times, and dry at 40-60° C. for 12-24 h to obtain the PMMA-PEI polymer microspheres.

2. The high heat-resistant PBT foam diffuser plate according to claim 1, characterized in that: The polymerization temperature was kept constant at 60°C.

3. The high heat-resistant PBT foam diffuser plate according to claim 1, characterized in that: The silane coupling agent is an aminosilane coupling agent or an epoxysilane coupling agent.

4. The high heat-resistant PBT foam diffuser plate according to claim 1, characterized in that: The antioxidant is any one of antioxidant 1024, antioxidant 1010 or antioxidant 1076.

5. The high heat-resistant PBT foam diffuser plate according to claim 1, characterized in that: The ultraviolet absorber is selected from any one of ultraviolet absorbers UV-327, UV-329, and UV-531.

6. The high heat-resistant PBT foam diffuser plate according to claim 1, characterized in that: The foaming agent is sodium bicarbonate.

7. The high heat-resistant PBT foam diffuser plate according to claim 1, characterized in that: The flame retardant is melamine.

8. The method for preparing a high heat-resistant PBT foamed diffuser plate according to any one of claims 1 to 7, characterized in that: The following steps are involved: Add the said weight proportions of anhydrous ethanol, PMMA-PEI polymer microspheres, sodium citrate, and silane coupling agent into a container, stir for 20 to 40 minutes at 40 to 60° C. to obtain a mixture a, then add the said weight proportions of PBT resin, antioxidant, ultraviolet absorber, light stabilizer, mineral oil, brightener, flame retardant, and foaming agent into the mixture a, stir evenly at a speed of 400 to 600 r / min, and finally put into a single screw extruder to heat, melt, and extrude to obtain a high heat-resistant PBT foamed diffusion plate; Among them, the temperatures of each zone of the single-screw extruder are: zone one temperature is 180~190℃, zone two temperature is 190~200℃, zone three temperature is 210~220℃, zone four temperature is 210~220℃, zone five temperature is 225~235℃, zone six temperature is 215~225℃, zone seven temperature is 210~220℃, die head temperature is 205~215℃, and the production speed is 320Kg / h.

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