Intrinsic flame-retardant PMMA resin material, flame-retardant resin composition, preparation method and application

Abstract

The application discloses an intrinsic flame-retardant PMMA resin material, a flame-retardant resin composition, a preparation method and application, and belongs to the technical field of flame-retardant modification of PMMA resin materials.The intrinsic flame-retardant PMMA resin material comprises the following raw materials: 70-95 parts of MMA, 5-30 parts of a halogen-free flame retardant and 0.01-0.05 parts of an initiator; meanwhile, in order to improve the flame-retardant effect, a transparent flame retardant is added to the above system to obtain a flame-retardant resin composition material.The intrinsic flame-retardant PMMA resin material is prepared by introducing a flame-retardant monomer with the structure of 'MMA+ flame-retardant group' and copolymerizing with MMA, the intrinsic flame-retardant PMMA resin material improves the flame-retardant performance while maintaining the good light transmission performance and mechanical performance of the PMMA resin itself; meanwhile, the transparent flame retardant is introduced into the system, the two kinds of flame retardants produce a compounding synergistic effect, and the prepared flame-retardant resin composition material has excellent flame-retardant performance, light transmission performance and mechanical performance.

Description

Technical Field

[0001] This invention belongs to the field of flame retardant modification technology of PMMA resin materials, specifically relating to an intrinsically flame retardant PMMA resin material, a flame retardant resin composition, a preparation method, and its application. Background Technology

[0002] Polymethyl methacrylate (PMMA) is widely used due to its excellent mechanical and optical properties, but its poor flame retardancy necessitates flame-retardant modification for fire-resistant applications. Currently, most commercially available flame-retardant PMMA systems are halogenated, but halogenated flame retardants pose safety hazards, severely limiting their application scope and scenarios. However, most halogen-free flame retardants are unsuitable for PMMA; introducing them reduces the material's transparency, causing it to lose its optical plastic properties. Therefore, how to modify PMMA to produce a highly transparent halogen-free flame-retardant PMMA resin material has become a pressing problem to be solved.

[0003] There are many existing methods for flame-retardant modification of PMMA. For example, based on nanotechnology, nano-flame retardants can be used to modify PMMA for transparent flame retardancy. However, while improving transparency, nano-flame retardants also increase haze, and the increased cost is a significant issue. Another method is to use liquid flame retardants for transparent flame retardant modification of PMMA. Although this effectively improves both light transmittance and haze, the addition of liquid flame retardants can affect the material's mechanical properties. Summary of the Invention

[0004] Based on the above-mentioned technical problems, this invention proposes an intrinsically flame-retardant PMMA resin material, a flame-retardant resin composition, a preparation method, and its application.

[0005] The technical solution adopted in this invention is: First, this invention provides an intrinsically flame-retardant PMMA resin material having the following structure: Wherein, R1 is selected from , Either of the two structures, R2 and R3 are independently selected from hydrogen, C1-C4 alkyl, phenyl or metal ions, n=1-3, m=1-30.

[0006] Secondly, the present invention provides a method for preparing an intrinsically flame-retardant PMMA resin material, comprising the following raw materials in parts by weight: 70-95 parts of methyl methacrylate, 5-30 parts of halogen-free flame retardant, and 0.01-0.05 parts of initiator.

[0007] Preferably, a method for preparing an intrinsically flame-retardant PMMA resin material includes the following steps: (1) Prepolymerization: Weigh the raw materials according to the above ratio, add the weighed methyl methacrylate to the reaction vessel, then add the weighed halogen-free flame retardant and stir until completely dissolved, then add the weighed initiator, raise the system temperature to 75-85℃ and keep it at that temperature for 25-35 minutes to obtain the prepolymer; this process is the self-polymerization of methyl methacrylate monomers to generate low molecular weight prepolymers; (2) Molding: Pour the prepolymer obtained in step (1) into a mold with a PTFE release cloth attached to its surface, and degas it under vacuum; (3) Polymerization: Place the degassed mold from step (2) into an oven at 55-65℃ and keep it warm for 3-5 hours. Then raise the temperature to 110-130℃ and keep it warm for 1.5-2.5 hours. Cool it down to room temperature and open the mold to obtain intrinsic flame-retardant PMMA resin material. This process is a copolymerization reaction between low molecular weight prepolymer and halogen-free flame retardant monomer to produce intrinsic flame-retardant PMMA resin.

[0008] In the above preparation method, step (1) first performs high-temperature prepolymerization to increase the viscosity of the material and avoid material leakage and overflow in the mold; step (3) first polymerizes at low temperature, and after reaching a certain degree of polymerization, the temperature is raised and then polymerized at high temperature to further increase the degree of polymerization of the material.

[0009] Preferably, in step (2): the mold is a hard metal mold.

[0010] Preferably, the halogen-free flame retardant has the following structure: Wherein, R1 is selected from , In either of the two structures, R2 and R3 are independently selected from hydrogen, C1-C4 alkyl, phenyl, or metal ions.

[0011] Preferably, the halogen-free flame retardant is selected from one or more of 2-methyl-2-acrylate (diphenylphosphoyl) methyl ester, 2-methyl-2-acrylate (dimethylphosphoyl) methyl ester, and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methacrylate-10-oxide; all of the above halogen-free flame retardants have the following structure: In the structure of 2-methyl-2-acrylate (diphenylphospho)methyl ester, the structure of R1 is as follows: Both R2 and R3 have phenyl structures; in the structure of 2-methyl-2-acrylate (dimethylphosphoryl)methyl ester, the structure of R1 is... Both R2 and R3 have a methyl structure; in the structure of 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methyl methacrylate-10-oxide, the structure of R1 is... .

[0012] Preferably, the initiator is selected from one or both of azobisisobutyronitrile (AIBN) and BPO (benzoyl peroxide).

[0013] Furthermore, the present invention provides a flame-retardant resin composition comprising the following components in parts by weight: 70-95 parts of methyl methacrylate, 5-30 parts of halogen-free flame retardant, 1-5 parts of transparent flame retardant, and 0.01-0.05 parts of initiator.

[0014] Preferably, the transparent flame retardant is selected from one or more of phosphorus-containing epoxy resins, phosphate esters, and phosphorus-containing polyols.

[0015] Preferably, the transparent flame retardant is selected from one or more of DPO-phenolic epoxy resin, dimethyl methyl phosphate, diethyl ethyl phosphate, and flame retardant FR8500; wherein DPO-phenolic epoxy resin is a phosphorus-containing epoxy resin flame retardant, dimethyl methyl phosphate and diethyl ethyl phosphate are both phosphate ester flame retardants, and FR8500 is a phosphorus-containing polyol flame retardant.

[0016] Preferably, the transparent flame retardant is selected from one or both of DPO-phenolic epoxy resin and flame retardant FR8500.

[0017] The method for preparing the flame-retardant resin composition described above includes the following steps: (1) Prepolymerization: Weigh the raw materials according to the above ratio, add the weighed methyl methacrylate to the reaction vessel, then add the weighed halogen-free flame retardant and transparent flame retardant and stir until completely dissolved, then add the weighed initiator, raise the system temperature to 75-85℃ and keep it at that temperature for 25-35 minutes to obtain the prepolymer; this process is the self-polymerization of methyl methacrylate monomers to generate low molecular weight prepolymers; (2) Molding: Pour the prepolymer obtained in step (1) into a mold with a PTFE release cloth attached to its surface, and degas it under vacuum; (3) Polymerization: Place the degassed mold from step (2) into an oven at 55-65℃ and keep it at that temperature for 3-5 hours. Then raise the temperature to 110-130℃ and keep it at that temperature for 1.5-2.5 hours. Then lower the temperature to room temperature and open the mold to obtain the flame retardant resin composition. This process involves the copolymerization reaction of low molecular weight prepolymer and halogen-free flame retardant monomer to generate intrinsic flame retardant PMMA resin material, which is then physically mixed with the transparent flame retardant added in step (1) to obtain the final flame retardant resin composition material.

[0018] In the above preparation method, step (1) first performs high-temperature prepolymerization to increase the viscosity of the material and avoid material leakage and overflow in the mold; step (3) first polymerizes at low temperature, and after reaching a certain degree of polymerization, the temperature is raised and then polymerized at high temperature to further increase the degree of polymerization of the material.

[0019] For testing purposes, the above-mentioned intrinsically flame-retardant PMMA resin material or flame-retardant resin composition material is injection molded into PMMA specimens, including the following steps: (1) The intrinsic flame-retardant PMMA resin material or flame-retardant resin composition material prepared above is crushed by a crusher to obtain resin granules; (2) Add the resin particles obtained in step (1) into the injection molding machine and perform injection molding to obtain the PMMA sample to be tested; the injection molding parameters are as follows: compression section temperature is 220-240℃, feeding section temperature is 185-205℃, melt temperature is 220-250℃, mold temperature is 40-80℃, and injection pressure is 80-140MPa; (3) Place the injection-molded sample into an oven, set the temperature to 70-80℃, and circulate hot air for 4 hours for annealing.

[0020] Finally, this invention provides an application of intrinsically flame-retardant PMMA resin material, which is used in the construction industry for windows, sunroofs, signs, and lighting fixtures where flame retardancy and transparency are required; in the automotive industry for car windows, taillight covers, and instrument clusters; in consumer electronics for electronic displays and lens optics; and in the medical field.

[0021] The beneficial technical effects of the present invention are as follows: This invention prepares an intrinsically flame-retardant PMMA resin material by copolymerizing a flame-retardant monomer with a "MMA + phosphorus-containing flame-retardant group" structure with MMA. Simultaneously, to enhance flame-retardant performance, a transparent flame retardant is added. The resulting flame-retardant resin composition material exhibits advantages such as excellent transparency, low haze, good flame retardancy, and superior mechanical properties. Specifically: (1) In this invention, a halogen-free flame retardant monomer with a structure of “MMA + phosphorus-containing flame retardant group” is copolymerized with MMA. The main chain structure of the intrinsic flame retardant PMMA resin material prepared is composed only of MMA units. While improving the flame retardant performance, it maintains the good light transmittance and mechanical properties of PMMA resin itself. Therefore, compared with the existing flame retardant modified PMMA resin materials, the intrinsic flame retardant PMMA resin material retains the original physical properties of PMMA resin material and can be directly used as PMMA resin material without mixing with other resin materials.

[0022] (2) The present invention introduces halogen-free flame retardant and transparent flame retardant into the resin system. The two produce a compound synergistic effect. The flame retardant resin composition material prepared has excellent flame retardant performance, light transmittance and mechanical properties. The flame retardant level can reach above V-1, the limiting oxygen index can reach above 24%, the light transmittance can reach above 92%, the haze is below 1.3%, and the good mechanical properties of PMMA resin itself are maintained.

[0023] (3) The intrinsic flame-retardant PMMA resin material prepared by the present invention can be used alone or mixed with PMMA modified resin materials with other special properties. Due to its unique molecular structure, the dispersion effect will be better when mixed. It can also be used as a flame retardant in other polymer materials. Due to its unique molecular structure, the compatibility with polymer materials will be better when mixed, so the application range is wide. Detailed Implementation

[0024] The present invention will be further described below with reference to specific embodiments. Unless otherwise specified, all chemical reagents used in the embodiments of the present invention are obtained through conventional commercial means.

[0025] In the following examples, 2-methyl-2-acrylate (diphenylphosphoyl) methyl ester, 2-methyl-2-acrylate (dimethylphosphoyl) methyl ester and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methyl methacrylate-10-oxide are products sold by Shandong Dongke Chemical Technology Co., Ltd.

[0026] Example 1

[0027] Preparation of intrinsic flame-retardant PMMA resin materials (1) 908.7g of methyl methacrylate monomer (MMA) was added to a reaction flask, and 91.3g of flame retardant monomer 2-methyl-2-acrylate (diphenylphosphomethyl) methyl ester was added. The mixture was heated and stirred until the flame retardant was dissolved. 0.3g of BPO was added, and the oil bath temperature was raised to 80°C and kept at that temperature for about 30 minutes until the system became viscous to obtain the prepolymer. (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0028] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0029] Preparation of PMMA test strips (1) The intrinsic flame-retardant PMMA resin material prepared above is crushed using a crusher to obtain resin granules; (2) Add the resin particles obtained in step (1) into the injection molding machine and perform injection molding to obtain the PMMA sample to be tested; the injection molding parameters are as follows: compression section temperature is 230℃, feeding section temperature is 200℃, melt temperature is 235℃, mold temperature is 60℃, and injection pressure is 110MPa. (3) Place the injection-molded sample into an oven, set the temperature to 75℃, and circulate hot air for 4 hours for annealing.

[0030] Example 2

[0031] Preparation of intrinsic flame-retardant PMMA resin materials (1) Add 908.7g of MMA to a reaction flask, add 91.3g of flame retardant monomer 2-meth-2-acrylate (dimethylphosphoryl) methyl ester, heat and stir until the flame retardant is dissolved, add 0.3g of BPO, heat the oil bath to 80℃, keep it at the temperature for about 30min until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0032] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0033] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0034] Example 3

[0035] Preparation of intrinsic flame-retardant PMMA resin materials (1) Add 908.7g of MMA to a reaction flask, add 91.3g of flame retardant monomer 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methyl methacrylate-10-oxide, heat and stir until the flame retardant dissolves, add 0.3g of BPO, heat the oil bath to 80℃, keep it at that temperature for about 30min until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0036] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0037] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0038] Example 4

[0039] Preparation of flame retardant resin composition materials (1) Add 908.7g of MMA to a reaction flask, add 61.3g of flame retardant monomer 2-methyl-2-acrylate (diphenylphosphomethyl) methyl ester and 30g of DPO-phenolic epoxy resin, heat and stir until the flame retardant is dissolved, add 0.3g of BPO, heat the oil bath to 80℃, keep it at that temperature for about 30min until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0040] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0041] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0042] Example 5

[0043] Preparation of flame retardant resin composition materials (1) Add 908.7g of MMA to a reaction flask, add 61.3g of flame retardant monomer 2-methyl-2-acrylate (diphenylphosphoyl) methyl ester and 30g of dimethyl methyl phosphate, heat and stir until the flame retardant is dissolved, add 0.3g of BPO, heat the oil bath to 80°C, keep it at that temperature for about 30 minutes until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0044] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0045] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0046] Example 6

[0047] Preparation of flame retardant resin composition materials (1) Add 908.7g of MMA to a reaction flask, add 61.3g of flame retardant monomer 2-methyl-2-acrylate (diphenylphosphoyl) methyl ester and 30g of diethyl ethyl phosphate, heat and stir until the flame retardant is dissolved, add 0.3g of BPO, heat the oil bath to 80°C, keep it at that temperature for about 30 minutes until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0048] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0049] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0050] Example 7

[0051] Preparation of flame retardant resin composition materials (1) Add 908.7g of MMA to a reaction flask, add 61.3g of flame retardant monomer 2-methyl-2-acrylate (diphenylphosphomethyl) methyl ester and 30g of flame retardant FR8500, heat and stir until the flame retardant is dissolved, add 0.3g of BPO, heat the oil bath to 80℃, keep it at that temperature for about 30min until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0052] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0053] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0054] Example 8

[0055] Preparation of flame retardant resin composition materials (1) Add 908.7g of MMA to a reaction flask, add 61.3g of flame retardant monomer 2-meth-2-acrylate (dimethylphosphoryl) methyl ester and 30g of DPO-phenolic epoxy resin, heat and stir until the flame retardant is dissolved, add 0.3g of BPO, heat the oil bath to 80℃, keep it at that temperature for about 30min until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0056] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0057] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0058] Example 9

[0059] Preparation of flame retardant resin composition materials (1) Add 908.7g of MMA to a reaction flask, add 61.3g of flame retardant monomer 2-methyl-2-acrylate (dimethylphosphoryl) methyl ester and 30g of dimethyl methyl phosphate, heat and stir until the flame retardant is dissolved, add 0.3g of BPO, heat the oil bath to 80°C, keep it at that temperature for about 30 minutes until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0060] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0061] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0062] Example 10

[0063] Preparation of flame retardant resin composition materials (1) Add 908.7g of MMA to a reaction flask, add 61.3g of flame retardant monomer 2-methyl-2-acrylate (dimethylphosphoryl) methyl ester and 30g of diethyl ethyl phosphate, heat and stir until the flame retardant is dissolved, add 0.3g of BPO, heat the oil bath to 80°C, keep it at that temperature for about 30min until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0064] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0065] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0066] Example 11

[0067] Preparation of flame retardant resin composition materials (1) Add 908.7g of MMA to a reaction flask, add 61.3g of flame retardant monomer 2-meth-2-acrylate and 30g of flame retardant FR8500, heat and stir until the flame retardant is dissolved, add 0.3g of BPO, heat the oil bath to 80°C, keep it at that temperature for about 30 minutes until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0068] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0069] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0070] Example 12

[0071] Preparation of flame retardant resin composition materials (1) 908.7g of MMA was added to a reaction flask, along with 61.3g of flame-retardant monomer 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methyl methacrylate-10-oxide and 30g of DPO-phenolic epoxy resin. The mixture was heated and stirred until the flame retardant dissolved. 0.3g of BPO was added, and the mixture was heated in an oil bath to 80°C and kept at that temperature for about 30 minutes until the system became viscous, thus obtaining the prepolymer. (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0072] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0073] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0074] Example 13

[0075] Preparation of flame retardant resin composition materials (1) 908.7g of MMA was added to a reaction flask, along with 61.3g of flame-retardant monomer 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methyl methacrylate-10-oxide and 30g of dimethyl methyl phosphate. The mixture was heated and stirred until the flame retardant dissolved. 0.3g of BPO was added, and the mixture was heated in an oil bath to 80°C and kept at that temperature for about 30 minutes until the system became viscous, thus obtaining the prepolymer. (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0076] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0077] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0078] Example 14

[0079] Preparation of flame retardant resin composition materials (1) 908.7g of MMA was added to a reaction flask, along with 61.3g of flame-retardant monomer 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methyl methacrylate-10-oxide and 30g of diethyl ethyl phosphate. The mixture was heated and stirred until the flame retardant dissolved. 0.3g of BPO was added, and the mixture was heated in an oil bath to 80°C and kept at that temperature for about 30 minutes until the system became viscous, thus obtaining the prepolymer. (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0080] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0081] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0082] Example 15

[0083] Preparation of flame retardant resin composition materials (1) 908.7g of MMA was added to a reaction flask, along with 61.3g of flame retardant monomer 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-methyl methacrylate-10-oxide and 30g of flame retardant FR8500. The mixture was heated and stirred until the flame retardant dissolved. 0.3g of BPO was added, and the mixture was heated in an oil bath to 80°C and kept at that temperature for about 30 minutes until the system became viscous, thus obtaining the prepolymer. (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow the flame retardant monomer and prepolymer to copolymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame retardant PMMA.

[0084] In step (1) above, high temperature prepolymerization is first performed to increase the viscosity of the material and prevent leakage and overflow in the mold; in step (3), low temperature polymerization is first performed, and after reaching a certain degree of polymerization, the temperature is raised and high temperature polymerization is performed to further increase the degree of polymerization of the material.

[0085] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0086] Comparative Example 1 (1) Add 1000g MMA to the reaction flask, add 0.3g BPO, heat the oil bath to 80℃, keep it warm for about 30min until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow MMA to self-polymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain PMMA.

[0087] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0088] Comparative Example 2 (1) Add 908.7g MMA into a reaction flask, add 91.3g DPO-phenolic epoxy resin, heat and stir until the flame retardant is dissolved, add 0.3g BPO, heat the oil bath to 80℃, keep it at the temperature for about 30min until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow MMA to self-polymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame-retardant PMMA.

[0089] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0090] Comparative Example 3 (1) Add 908.7g MMA to a reaction flask, add 91.3g dimethyl methyl phosphate, heat and stir until the flame retardant dissolves, add 0.3g BPO, heat the oil bath to 80℃, keep it warm for about 30min until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow MMA to self-polymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame-retardant PMMA.

[0091] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0092] Comparative Example 4 (1) Add 908.7g MMA to a reaction flask, add 91.3g diethyl ethyl phosphate, heat and stir until the flame retardant dissolves, add 0.3g BPO, heat the oil bath to 80℃, keep it at that temperature for about 30min until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow MMA to self-polymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame-retardant PMMA.

[0093] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0094] Comparative Example 5 (1) Add 908.7g MMA to the reaction flask, add 91.3g flame retardant FR8500, heat and stir until the flame retardant dissolves, add 0.3g BPO, heat the oil bath to 80℃, keep it at that temperature for about 30min until the system becomes viscous, and obtain the prepolymer; (2) Pour the prepolymer from step (1) into a metal mold with a PTFE release cloth on the surface. The mold is a metal plate mold with a metal gasket in the middle and screws for fixing and clamping; vacuum degassing. (3) Place the mold in a 60℃ oven and keep it warm for 4 hours to allow MMA to self-polymerize. Then raise the temperature to 120℃ and keep it warm for 2 hours to polymerize at high temperature and increase the degree of polymerization of the board. Slowly lower the temperature to room temperature and open the mold to obtain flame-retardant PMMA.

[0095] Preparation of PMMA test strips The preparation method is the same as in Example 1.

[0096] Performance testing The PMMA test strips prepared in Examples 1-15 and Comparative Examples 1-5 were subjected to flame retardant performance tests (UL94 and LOI), transparency performance tests (light transmittance and haze), and mechanical performance tests (tensile strength, elongation at break, and notched impact strength). The test results are shown in Table 1.

[0097] Test method description: UL94 refers to the UL94 flame retardant test. LOI refers to the Limiting Oxygen Index test.

[0098] Table 1 Performance Test Results As can be seen from the performance test results in Table 1, Comparative Example 1 is a pure PMMA resin material with excellent light transmittance and mechanical properties, but poor flame retardant properties.

[0099] To improve the flame retardant properties of PMMA resin, a halogen-free flame retardant was added to modify it. A flame retardant monomer with a "MMA + phosphorus-containing flame retardant group" structure was copolymerized with MMA to prepare an intrinsically flame retardant PMMA resin material (see Examples 1-3 in Table 1). Compared with pure PMMA resin, this resin material has improved flame retardant properties. Moreover, since its main chain is composed only of MMA units, it maintains the good light transmittance and mechanical properties of PMMA resin while improving flame retardant properties.

[0100] To further improve the flame retardant properties of PMMA resin, a transparent flame retardant was added to the resin system to prepare a flame retardant resin composition material (see Examples 4-15 in Table 1). In this resin system, the transparent flame retardant and the flame retardant groups in the halogen-free flame retardant structure produce a compound synergistic effect, which further improves the flame retardant properties. The flame retardant rating can reach above V-1, and the limiting oxygen index can reach above 24%. At the same time, it also has good light transmittance and mechanical properties. In particular, when the transparent flame retardant is DPO-phenolic epoxy resin (Examples 4, 8, 12) or FR8500 (Examples 7, 11, 15), the flame retardant rating can reach V-0 and the limiting oxygen index can reach above 25% while maintaining good light transmittance and mechanical properties.

[0101] Compared with Examples 4-15, Comparative Examples 2-5 replaced the halogen-free flame retardant with an equal amount of transparent flame retardant, resulting in a resin system consisting of pure PMMA resin material and transparent flame retardant. Due to the lack of the synergistic effect between the flame-retardant groups in the transparent flame retardant and halogen-free flame retardant structures, the flame-retardant effect was still poor even with the addition of the same mass of flame retardant. At the same time, since the added flame retardant did not have the "MMA + phosphorus-containing flame-retardant group" structure and could not copolymerize with MMA to form a structure whose main chain consisted only of MMA units, it seriously affected the good light transmittance and mechanical properties of the PMMA resin itself.

[0102] For any parts not mentioned in the above embodiments, existing technologies can be adopted or referenced.

[0103] Of course, the above description is not intended to limit the present invention, and the present invention is not limited to the above embodiments. Any changes, modifications, additions or substitutions made by those skilled in the art within the scope of the present invention should be protected by the present invention.

Claims

1. A flame-retardant resin composition, characterized in that, Including intrinsically flame-retardant PMMA resin materials and transparent flame retardants; The intrinsically flame-retardant PMMA resin material has the following structure: Wherein, R1 is selected from R2 and R3 are independently selected from phenyl and methyl, respectively, n=1-3, m=1-30; The intrinsic flame-retardant PMMA resin material comprises the following raw materials in parts by weight: 70-95 parts of methyl methacrylate, 5-30 parts of halogen-free flame retardant, and 0.01-0.05 parts of initiator; The preparation method of the intrinsically flame-retardant PMMA resin material includes the following steps: (1) Prepolymerization: Weigh the raw materials according to the above ratio, add the weighed methyl methacrylate to the reaction vessel, add the weighed halogen-free flame retardant and stir until completely dissolved, then add the weighed initiator, raise the system temperature to 75-85℃ and keep it at that temperature for 25-35 minutes to obtain the prepolymer. (2) Molding: Pour the prepolymer obtained in step (1) into a mold with a PTFE release cloth attached to its surface, and degas it under vacuum; (3) Polymerization: Place the degassed mold from step (2) into an oven at 55-65℃ and keep it warm for 3-5 hours. Then raise the temperature to 110-130℃ and keep it warm for 1.5-2.5 hours. Cool it down to room temperature and open the mold to obtain intrinsic flame-retardant PMMA resin material. The intrinsically flame-retardant PMMA resin material is used in the construction industry for windows, skylights, signs, and lighting fixtures where flame retardancy and transparency are required; in the automotive industry for car windows, taillight covers, and instrument clusters; in consumer electronics for electronic displays and lens optics; and in the medical field. The halogen-free flame retardant is selected from one or two of 2-methyl-2-acrylate and 2-methyl-2-acrylate. The transparent flame retardant is selected from one or more of phosphorus-containing epoxy resins, phosphate esters, and phosphorus-containing polyols.

2. The flame-retardant resin composition according to claim 1, characterized in that, The initiator is selected from one or both of azobisisobutyronitrile (AIBN) and BPO.

3. A method for preparing a flame-retardant resin composition according to any one of claims 1 to 2, characterized in that, Includes the following steps: (1) Prepolymerization: Weigh the raw materials according to the above ratio, add the weighed methyl methacrylate to the reaction vessel, then add the weighed halogen-free flame retardant and transparent flame retardant and stir until completely dissolved, then add the weighed initiator, raise the system temperature to 75-85℃ and keep it at that temperature for 25-35 minutes to obtain the prepolymer. (2) Molding: Pour the prepolymer obtained in step (1) into a mold with a PTFE release cloth attached to its surface, and degas it under vacuum; (3) Polymerization: Place the degassed mold from step (2) into an oven at 55-65℃ and keep it warm for 3-5 hours. Then raise the temperature to 110-130℃ and keep it warm for 1.5-2.5 hours. Cool it down to room temperature and open the mold to obtain the flame retardant resin composition.

Images