Methyl methacrylate polymer, preparation method therefor, and use thereof

Abstract

The present invention relates to the field of polymer materials. Disclosed are a methyl methacrylate polymer, a preparation method therefor, and a use thereof. The polymer comprises structural unit A and, optionally, structural unit B; the polymer has an isotacticity (mm) of 4.1-10%; a syndiotacticity (rr) of 45-60%; and a melt index of 2-10 g / 10 min at 230 °C and 3.8 kg. The methyl methacrylate polymer is characterized by uniform molecular weight, low isotacticity, and good processability.

Description

Methyl methacrylate polymers, their preparation methods and applications Technical Field

[0001] This invention relates to the field of polymer materials, specifically to a methyl methacrylate polymer, its preparation method, and its applications. Background Technology

[0002] Polymethyl methacrylate (PMMA), also known as plexiglass or acrylic, is a polymer compound made by polymerizing methyl methacrylate and optional comonomers. This material is known for its smooth surface, high transparency, lightweight, high strength, corrosion resistance, UV aging resistance, good insulation, and sound insulation properties.

[0003] PMMA can be produced through various polymerization processes, including bulk polymerization, suspension polymerization, and solution polymerization. Each process has its own characteristics and significantly impacts the performance of the final product. Bulk polymerization is highly valued for its ability to produce PMMA materials with high transmittance (over 92.5%) and low haze (less than 0.3%), making it a preferred choice for high-end optical materials. However, bulk polymerization results in high system viscosity, low mass and heat transfer efficiency, and a tendency for self-acceleration, which negatively affect the optical and mechanical properties of the material. Compared to bulk polymerization, suspension polymerization and solution polymerization are more mature processes with better mass and heat transfer, but the PMMA materials produced by these methods have relatively low transmittance and are not suitable for high-end optical applications.

[0004] With the increasing demand for high-end PMMA products, the synthesis of high-end optical-grade PMMA materials using bulk polymerization is gradually becoming a focus of research. The aim is to improve the performance of PMMA materials and optimize the bulk polymerization process. Summary of the Invention

[0005] One objective of this invention is to overcome the problems of non-uniform molecular weight, high isotacticity, and poor processability of methyl methacrylate polymers in the prior art, and to provide a methyl methacrylate polymer with uniform molecular weight, low isotacticity, and good processability, as well as excellent optical properties. Another objective of this invention is to overcome the problems of poor polymerization controllability, poor mass and heat transfer, and easy gelation in the polymerization process of methyl methacrylate in the prior art, and to provide a method for preparing a methyl methacrylate polymer with good polymerization controllability, good mass and heat transfer, and less susceptibility to gelation.

[0006] To achieve the above objectives, a first aspect of the present invention provides a methyl methacrylate polymer, wherein the polymer comprises structural unit A and optionally structural unit B;

[0007] Wherein, the structural unit A has the structure shown in Equation I,

[0008] Wherein, the structural unit B has the structure shown in Formula II and / or Formula III,

[0009] Wherein, R1 is selected from C2-C4 straight-chain or branched alkyl groups, and R2 is selected from H or C1-C3 straight-chain or branched alkyl groups;

[0010] Wherein, the isotacticity (mm) of the polymer is 4.1-10%, preferably 4.1-9.5%, more preferably 4.2-8.5%; and the syndiotacticity (rr) is 45-60%, preferably 50-59%, more preferably 52-59%; and

[0011] The polymer has a melt index of 2-10 g / 10 min at 230 °C and 3.8 kg, preferably 3-10 g / 10 min, and more preferably 4-10 g / 10 min.

[0012] A second aspect of the present invention provides a method for preparing a methyl methacrylate polymer, comprising the following steps:

[0013] (1) In the presence of a protective gas, methyl methacrylate, optionally comonomer X, chain transfer agent and initiator I are subjected to a prepolymerization reaction in reactor I to obtain a prepolymer solution containing the prepolymer; and

[0014] (2) In the presence of a protective gas, the prepolymer solution containing the prepolymer is subjected to a final polymerization reaction in reactor II to obtain the methyl methacrylate polymer;

[0015] Step (2) is carried out in the presence of initiator II;

[0016] Wherein, the initiator II is different from the initiator I, and the initiator II is one or more of the compounds shown in Formula IV.

[0017] R3-R8 are each independently selected from hydrogen, C1-C10 alkyl, C3-C10 cycloalkyl, C6-C15 aryl, C7-C15 arylalkyl and C7-C15 alkylaryl; or one or more pairs of R3 / R4, R5 / R6 and R7 / R8 can form an alicyclic ring of 3-15 atoms together with the carbon atoms attached to them;

[0018] Preferably, R3-R8 are each independently selected from hydrogen and C1-C6 alkyl; or each pair of R3 / R4, R5 / R6, and R7 / R8 independently forms a five-membered, six-membered, or seven-membered alicyclic ring together with the carbon atom to which they are attached.

[0019] In some embodiments, steps (1) and (2) are carried out in the presence of initiator II. In some embodiments, the temperature of the final polymerization reaction is higher than the temperature of the prepolymerization reaction. In some embodiments, the reaction temperature of the prepolymerization reaction in step (1) is 80-130°C, preferably 85-125°C, and the temperature of the final polymerization reaction is higher than the temperature of the prepolymerization reaction.

[0020] In some embodiments, preferably, the methyl methacrylate polymer prepared by the preparation method is the methyl methacrylate polymer of the first aspect.

[0021] The third aspect of the present invention provides a methyl methacrylate polymer prepared by the preparation method described in the second aspect above; preferably, the methyl methacrylate polymer is the methyl methacrylate polymer of the first aspect.

[0022] The fourth aspect of the present invention provides the use of the methyl methacrylate polymer described in the first or third aspect above in at least one of liquid crystal displays, optical materials, automotive headlights, and electronic products.

[0023] The methyl methacrylate polymer provided by this invention has the characteristics of uniform molecular weight, low isotacticity and good processing performance, and also has excellent optical properties, which is beneficial for the application of methyl methacrylate polymer in at least one of liquid crystal displays, optical materials, automotive headlights and electronic products.

[0024] The methyl methacrylate polymer of the present invention exhibits excellent light transmittance, with a transmittance of 92.5% or higher, reaching optical grade levels. Furthermore, the methyl methacrylate polymer of the present invention has a more uniform molecular weight (manifested as a lower molecular weight distribution (Mw / Mn)) and lower isotacticity (mm).

[0025] The polymerization method of this invention achieves precise control over methyl methacrylate polymers. This method simplifies the preparation process, ensures the controllability of the polymerization process, and optimizes mass and heat transfer, reducing the occurrence of gelation. This invention achieves highly efficient initiation by combining initiator I and initiator II; in particular, initiator II used in this invention can decompose into free radicals in an orderly manner, maintaining a relatively stable free radical concentration, which significantly improves the controllability of the polymerization reaction rate. Under suitable reaction conditions, initiator II has a stable and controllable free radical generation capacity. Compared to initiators with excessively low activity, initiator II can fully ensure the smooth progress of the polymerization reaction within a reasonable time period; compared to initiators with excessively high activity, initiator II can effectively avoid adverse phenomena such as local overheating and explosive polymerization caused by overly vigorous reactions. In particular, the combined use of initiator I and initiator II in this invention is more conducive to obtaining methyl methacrylate polymers with uniform molecular weight, low isotacticity, and excellent processing properties. Detailed Implementation

[0026] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0027] Unless otherwise specified, all percentages, parts, ratios, etc. mentioned in this invention are based on weight, unless being based on weight would not be in accordance with the common understanding of those skilled in the art.

[0028] The first aspect of the present invention provides a methyl methacrylate polymer, wherein the polymer includes structural unit A and optionally structural unit B;

[0029] Wherein, the structural unit A has the structure shown in Equation I,

[0030] Wherein, the structural unit B has the structure shown in Formula II and / or Formula III,

[0031] Wherein, R1 is selected from C2-C4 straight-chain or branched alkyl groups, and R2 is selected from H or C1-C3 straight-chain or branched alkyl groups;

[0032] Wherein, the isotacticity (mm) of the polymer is 4.1-10%, preferably 4.1-9.5%, more preferably 4.2-8.5%; and the syndiotacticity (rr) is 45-60%, preferably 50-59%, more preferably 52-59%; and

[0033] The polymer has a melt index of 2-10 g / 10 min at 230 °C and 3.8 kg, preferably 3-10 g / 10 min, and more preferably 4-10 g / 10 min.

[0034] This invention controls the isotacticity and melt index of the polymer within the above-mentioned range, successfully achieving a polymer that has both molecular weight uniformity and low isotacticity characteristics, while also possessing excellent processing and optical properties.

[0035] According to the present invention, preferably, in some embodiments, the isotacticity of the polymer is 4.5-8.0%.

[0036] According to the present invention, preferably, in some embodiments, the syndiotacticity of the polymer is 52.0-58.5%.

[0037] According to the present invention, preferably, in some embodiments, the polymer has a melt index of 5-9 g / 10 min at 230°C and 3.8 kg.

[0038] In this invention, polymer isotacticity and melt index within the above-mentioned preferred ranges are more conducive to improving the processing performance of the polymer.

[0039] This invention calculates the isotacticity and syndiotacticity of polymers by measuring their proton NMR spectra, for example using a Swiss Bruker AV 300 nuclear magnetic resonance spectrometer, based on the integrated area of ​​the proton NMR spectrum.

[0040] In this invention, the isotacticity of a polymer refers to the proportion (mm) of isotactic stereostructures to all stereostructures in the polymer chain; the syndiotacticity of a polymer refers to the proportion (rr) of syndiotactic stereostructures to all stereostructures in the polymer chain. In this invention, for methyl methacrylate polymers with equal molecular weight, a lower isotacticity is more beneficial for improving the polymer's processing performance.

[0041] In this invention, the melt index (also known as melt flow rate) of the polymer refers to the mass (in grams) of polymer melt that passes through a standard capillary tube within 10 minutes under certain temperature and pressure. It is an important indicator for measuring the melt flowability of polymers. The methyl methacrylate polymer of this invention has a high melt index, which is more beneficial for improving the polymer's processing performance. In this invention, the polymer melt index was tested according to ISO 1133-1:2022 at 230°C and 3.8 kg.

[0042] In some embodiments of this invention, the isotacticity of the polymer can be 4.1%, 4.2%, 4.3%, 4.4%, 4.5%, 4.6%, 4.7%, 4.8%, 4.9%, 5.0%, 5.1%, 5.2%, 5.3%, 5.4%, 5.5%, 5.6%, 5.7%, 5.8%, 5.9%, 6.0%, 6.2%, 6.4%, 6.6%, 6.8%, 7.0%, and 7.2%. %, 7.4%, 7.6%, 7.8%, 8.0%, 8.1%, 8.2%, 8.3%, 8.4%, 8.5%, 8.6%, 8.7%, 8.8%, 8.9%, 9.0%, 9.1%, 9.2%, 9.3%, 9.4%, 9.5%, 9.6%, 9.7%, 9.8%, 9.9%, 10.0%, or a range of any two or more values, such as 5-8.5% or 4.1-7.6%.

[0043] In some embodiments of the present invention, the syndiotacticity of the polymer can be 45%, 46%, 47%, 48%, 49%, 50%, 51%, 52%, 53%, 54%, 55%, 56%, 57%, 58%, 59%, 60%, or a range of any two or more values, such as 53-58% or 54-58%.

[0044] In some embodiments of this invention, the melt index of the polymer at 230°C and 3.8 kg can be 2 g / 10 min, 2.5 g / 10 min, 3 g / 10 min, 3.5 g / 10 min, 4.0 g / 10 min, 4.1 g / 10 min, 4.2 g / 10 min, 4.3 g / 10 min, 4.4 g / 10 min, 4.5 g / 10 min, 4.6 g / 10 min, 4.7 g / 10 min, 4.8 g / 10 min, 4.9 g / 10 min, 5.0 g / 10 min, 5.2 g / 10 min, 5.4 g / 10 min, 5.6 g / 10 min, 5.8 g / 10 min, 6.0 g / 10 min, 6.2 g / 10 min, 6.4 g / 10 min, 6.6 g / 10 min, 6.8 g / 10 min, 7.0 g / 10 min, 7.2 g / 10 min, 7.4 g / 10 min, 7.6 g / 10 min, 7.8 g / 10 min, 8.0 g / 10 min, 8.2 g / 10 min, 8.4 g / 10 min, 8.6 g / 10 min, 8.8 g / 10 min, 9.0 g / 10 min, 9.2 g / 10 min, 9.4 g / 10 min, 9.6 g / 10 min, 9.8 g / 10 min, 10.0 g / 10 min, or any range of two or more values, such as 4.0-9.0 g / 10 min or 4.0-8.0 g / 10 min.

[0045] In this invention, "optionally" means that the polymer may include structural unit A and structural unit B, or may include only structural unit A; those skilled in the art can make the selection according to actual needs, and this invention does not particularly limit this.

[0046] In this invention, C2-C4 straight-chain or branched alkyl groups refer to saturated hydrocarbon groups containing 2 to 4 carbon atoms, and these alkyl groups can be straight-chain or branched, for example, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl.

[0047] In this invention, C1-C3 straight-chain or branched alkyl refers to an alkyl group containing 1 to 3 carbon atoms, and these alkyl groups can be straight-chain or branched, for example, methyl, ethyl, n-propyl or isopropyl.

[0048] In this invention, there is no particular limitation on the relative position of R2 on the benzene ring, and those skilled in the art can select it according to actual needs; for example, R2 can be in the ortho, meta, or para position on the benzene ring.

[0049] According to the present invention, in some embodiments, the content of structural unit A, based on the total weight of the polymer, can be 70-100 wt%, preferably 80-100 wt%, more preferably 90-100 wt%, for example 95-100 wt%, and the content of structural unit B can be 0-30 wt%, preferably 0-20 wt%, more preferably 0-10 wt%, for example 0-5 wt%. For example, based on the total weight of the polymer, the content of structural unit A can be 70 wt%, 72 wt%, 74 wt%, 75 wt%, 76 wt%, 78 wt%, 80 wt%, 82 wt%, 84 wt%, 85 wt%, 86 wt%, 88 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 100 wt%, or any range of two or more values, for example 91-100 wt%. For example, based on the total weight of the polymer, the content of structural unit B can be 30 wt%, 28 wt%, 26 wt%, 25 wt%, 24 wt%, 22 wt%, 20 wt%, 18 wt%, 16 wt%, 15 wt%, 14 wt%, 12 wt%, 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0 wt%, or any range of two or more values, such as 9-0 wt%. In this invention, the content of structural unit B refers to the total content of all structural units B.

[0050] In this invention, the contents of structural unit A and structural unit B can be obtained by measuring the proton spectrum of the polymer, for example using a Swiss Bruker AV 300 nuclear magnetic resonance spectrometer, and calculated based on the integrated area of ​​the proton spectra of structural unit A and structural unit B.

[0051] In this invention, the content of structural unit A and structural unit B within the above-mentioned range is more conducive to improving the performance of methyl methacrylate polymer.

[0052] According to the present invention, in some embodiments, preferably, the glass transition temperature of the polymer is 100-125°C, more preferably 105-125°C, and even more preferably 110-120°C.

[0053] In some embodiments of the present invention, the glass transition temperature of the polymer can be 100°C, 105°C, 110°C, 111°C, 112°C, 113°C, 114°C, 115°C, 116°C, 117°C, 118°C, 119°C, 120°C, 125°C, 130°C, or any range of two or more values, such as 105-122°C or 110-116°C.

[0054] This invention employs differential scanning calorimetry (DSC) using a differential scanning calorimeter (e.g., DSC8500) to test the glass transition temperature T of polymers. g .

[0055] In this invention, the polymer has a moderate glass transition temperature, which is more conducive to maintaining good processing performance.

[0056] According to some embodiments of the present invention, the weight-average molecular weight of the polymer may be 7.5 × 10⁻⁶. 4 -15×10 4 g / mol, preferably 8×10 g / mol 4 -14×10 4 g / mol. For example, the weight-average molecular weight of the polymer can be 7.5 × 10⁻⁶ g / mol. 4 7.6×10 4 7.8×10 4 8.0×10 4 8.2×10 4 8.4×10 4 8.5×10 4 8.6×10 4 8.8×10 4 9.0×10 4 9.2×10 4 9.4×10 4 9.5×10 4 9.6×10 4 9.8×10 4 10.0×10 4 10.2×10 4 10.4×10 4 10.5×10 4 10.6×10 4 10.8×10 4 11.0×10 4 11.2×10 4 11.4×10 4 11.5×10 4 11.6×10 4 11.8×10 4 12.0×10 4 12.2×10 4 12.4×10 4 12.5×10 4 12.6×10 4 12.8×10 4 13.0×10 413.2×10 4 13.4×10 4 13.5×10 4 13.6×10 4 13.8×10 4 14.0×10 4 or any range consisting of two or more values, such as 8.0 × 10 4 -13.5×10 4 g / mol.

[0057] According to the present invention, in some embodiments, the molecular weight distribution (Mw / Mn) of the polymer can be 1.80-2.40, preferably 1.80-2.30, and more preferably 1.80-2.25. For example, the molecular weight distribution (Mw / Mn) of the polymer can be 1.80, 1.82, 1.84, 1.85, 1.86, 1.88, 1.90, 1.92, 1.94, 1.95, 1.96, 1.98, 2.00, 2.02, 2.04, 2.05, 2.06, 2.08, 2.10, 2.12, 2.14, 2.15, 2.16, 2.18, 2.20, 2.22, 2.24, 2.25, 2.26, 2.28, 2.30, 2.32, 2.34, 2.35, 2.36, 2.38, 2.40, or a range of any two or more values, such as 1.85-2.20 or 1.90-2.20.

[0058] This invention employs gel permeation chromatography (GPC) using a gel permeation chromatograph (e.g., PL-GPC220) to measure the molecular weight and distribution of polymers.

[0059] In some embodiments of the present invention, the polymer has a higher molecular weight and a narrower molecular weight distribution, which is more conducive to improving processing performance and light transmittance.

[0060] In some embodiments of the present invention, the polymer has a higher melt index, which is more conducive to product processing and application.

[0061] According to the present invention, in some embodiments, the content of residual monomers in the polymer may be less than or equal to 0.40% by weight, preferably less than or equal to 0.35% by weight. In some embodiments, the content of residual monomers in the polymer may be less than or equal to 0.34% by weight, less than or equal to 0.33% by weight, less than or equal to 0.32% by weight, less than or equal to 0.31% by weight, less than or equal to 0.30% by weight, less than or equal to 0.29% by weight, less than or equal to 0.28% by weight, less than or equal to 0.27% by weight, less than or equal to 0.26% by weight, or less than or equal to 0.25% by weight.

[0062] This invention calculates the residual monomer content in a polymer by measuring its proton NMR spectrum, for example using a Swiss Bruker AV 300 nuclear magnetic resonance spectrometer, based on the integral area of ​​the proton NMR spectrum.

[0063] It should be noted that, in this invention, residual monomers refer to all the raw material monomers remaining in the polymer used to prepare methyl methacrylate polymers.

[0064] In this invention, the polymer has high light transmittance, which is more conducive to improving product quality and application.

[0065] According to the present invention, in some embodiments, the transmittance of the polymer, as determined according to ISO 13468-2:2021, is greater than or equal to 92.0%, preferably greater than or equal to 92.5%, for example greater than or equal to 92.6%, greater than or equal to 92.7%, greater than or equal to 92.8%, greater than or equal to 92.9%, or greater than or equal to 93.0%. In some embodiments, the transmittance of the polymer, as determined according to ISO 13468-2:2021, is less than or equal to 94.0%, preferably less than or equal to 93.5%, for example less than or equal to 93.4%, less than or equal to 93.3%, less than or equal to 93.2%, or less than or equal to 93.1%. For example, as determined according to ISO 13468-2:2021, the transmittance of the polymer is less than or equal to 93.5% and greater than or equal to 92.5%. In some embodiments, preferably, the transmittance of the polymer is less than or equal to 93.5% and greater than or equal to 93.0%, as determined according to ISO 13468-2:2021.

[0066] According to the present invention, in some embodiments, the haze of the polymer, as determined according to ISO 14782:2021, is less than or equal to 0.35%, preferably less than or equal to 0.30%, for example less than or equal to 0.29%, less than or equal to 0.28%, less than or equal to 0.27%, less than or equal to 0.26%, or less than or equal to 0.25%. In some embodiments, the haze of the polymer, as determined according to ISO 14782:2021, is greater than or equal to 0.20%, or greater than or equal to 0.21%. For example, the haze of the polymer is less than or equal to 0.31% and greater than or equal to 0.20%.

[0067] A second aspect of the present invention provides a method for preparing a methyl methacrylate polymer, comprising the following steps:

[0068] (1) In the presence of a protective gas, methyl methacrylate, optionally comonomer X, chain transfer agent and initiator I are subjected to a prepolymerization reaction in reactor I to obtain a prepolymer solution containing the prepolymer; and

[0069] (2) In the presence of a protective gas, the prepolymer solution containing the prepolymer is subjected to a final polymerization reaction in reactor II to obtain the methyl methacrylate polymer;

[0070] Step (2) is carried out in the presence of initiator II;

[0071] Wherein, the initiator II is different from the initiator I, and the initiator II is one or more of the compounds shown in Formula IV.

[0072] R3-R8 are each independently selected from hydrogen, C1-C10 alkyl, C3-C10 cycloalkyl, C6-C15 aryl, C7-C15 aralkyl and C7-C15 alkylaryl; or one or more pairs of R3 / R4, R5 / R6 and R7 / R8 can form an alicyclic ring of 3-15 atoms together with the carbon atoms attached to them.

[0073] In some embodiments of the present invention, R3-R8 are each independently selected from hydrogen and C1-C10 alkyl groups, preferably each independently selected from hydrogen and C1-C6 alkyl groups, for example each independently selected from hydrogen and C1-C4 alkyl groups.

[0074] In this invention, the C1-C10 alkyl group may be selected from, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl, nonyl, and decyl.

[0075] In this invention, the C3-C10 cycloalkyl group can be selected from, for example, cyclopropyl, cyclobutyl, cyclopentyl, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, and cyclodecyl.

[0076] In this invention, the C6-C15 aryl group can be selected from, for example, phenyl, naphthyl, fluorenyl, anthraceneyl, phenanthryl, biphenyl, etc.

[0077] In this invention, the aryl group in the C7-C15 aralkyl group can be selected from, for example, phenyl, biphenyl, naphthyl, fluorenyl, phenanthryl and anthracene, and the alkyl group in the C7-C15 aralkyl group can be selected from methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl and nonyl.

[0078] In this invention, the aryl group in the C7-C15 alkylaryl group can be selected from, for example, phenyl, biphenyl, naphthyl, fluorenyl, phenanthryl and anthracene, and the alkyl group in the C7-C15 aralkyl group can be selected from, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl, heptyl, octyl and nonyl.

[0079] In this invention, the C1-C6 alkyl group may be selected from, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, and hexyl.

[0080] In this invention, the C1-C4 alkyl group may be selected from, for example, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl and tert-butyl.

[0081] In some embodiments of the present invention, each pair of R3 / R4, R5 / R6 and R7 / R8 independently forms a five-membered, six-membered or seven-membered alicyclic ring together with the carbon atoms to which they are attached, preferably a six-membered alicyclic ring.

[0082] The method of the present invention uses initiator I and initiator II to achieve multi-stage, multi-functionality initiation, thereby improving production efficiency and the overall performance of the product.

[0083] The method of the present invention uses initiator II as shown in Formula IV, which is more conducive to providing stable free radicals and initiating the polymerization reaction of methyl methacrylate monomers, and can effectively control the (weight-average) molecular weight of the polymer; initiator II can promote the polymerization reaction, reduce the residue of unreacted monomers, and is more conducive to improving the mechanical and optical properties of the product.

[0084] The method of this invention employs initiator I and initiator II, which enables efficient initiation and effective control of the polymerization rate. Initiator I is beneficial to the prepolymerization process, achieving stable polymerization of methyl methacrylate.

[0085] The method of this invention employs initiator II, as shown in Formula IV, which is more conducive to effectively controlling the polymerization reaction. The initiator structure of Formula IV contains multiple peroxy groups (-OO-), which have high activation energies. Under relatively high reaction temperatures, these peroxy bonds generate free radicals stepwise to initiate the polymerization reaction. The special structure of initiator II allows it to generate free radicals gradually in a relatively stable and controllable manner, maintaining a relatively stable free radical concentration in the system, thus facilitating precise control of the polymerization reaction. Compared to initiators with excessively low activity, initiator II ensures the reaction proceeds within a reasonable timeframe; compared to initiators with excessively high activity, initiator II avoids overly vigorous reactions leading to problems such as localized overheating and explosive polymerization; thereby effectively improving production efficiency and product stability.

[0086] According to the present invention, after the final polymerization reaction is completed, the yield of the final polymer can be equal to or greater than 80 wt%, preferably equal to or greater than 85 wt%. According to the present invention, after the final polymerization reaction is completed, the yield of the final polymer can be equal to or less than 95 wt%, preferably equal to or less than 90 wt%. In some embodiments, after the final polymerization reaction is completed, the yield of the final polymer can be 80 wt%, 81 wt%, 82 wt%, 83 wt%, 84 wt%, 85 wt%, 86 wt%, 87 wt%, 88 wt%, 89 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, or any range of any two of the above values, for example, 80 wt%-95 wt% or 85 wt%-90 wt%.

[0087] According to the present invention, in some embodiments, based on the total weight of methyl methacrylate and comonomer X, the amount of initiator I can be 0.01-1.5% by weight, preferably 0.1-1% by weight, for example, 0.01, 0.02, 0.04, 0.06, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.1, 1.2, 1.3, 1.4, 1.5% by weight, or any range of any two of the above values, for example, 0.2-0.8% by weight. In some embodiments, the present invention, by controlling the amount of initiator I, facilitates the prepolymerization reaction process; more preferably, the amount of initiator I can be 0.2-0.6% by weight.

[0088] According to the present invention, in some embodiments, based on the total weight of methyl methacrylate and comonomer X, the amount of initiator II can be 0.05-2.0% by weight, preferably 0.1-1.5% by weight, for example, it can be 0.05, 0.06, 0.08, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35, 0.4, 0.45, 0.5, 0.55, 0.6, 0.65, 0.7, 0.75, 0.8, 0.85, 0.9, 0.95, 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9, 2.0% by weight or any range of any two of the above values, for example, 0.1-0.8% by weight. In some embodiments, the present invention facilitates the final polymerization process by controlling the amount of initiator II; more preferably, the amount of initiator II can be 0.1-0.5% by weight.

[0089] This invention, by adjusting the content of initiator I and initiator II, is more conducive to achieving multi-stage, multi-functional initiation, thereby improving the performance of methyl methacrylate polymers and controlling the polymerization process.

[0090] This invention, by regulating the content of initiator I and initiator II, is more conducive to the stable progress of the polymerization reaction, controls the polymerization process, reduces the occurrence of gelation, and improves the overall performance of methyl methacrylate polymer.

[0091] According to the present invention, in some embodiments, based on the total weight of methyl methacrylate and comonomer X, the amount of methyl methacrylate can be 70-100% by weight, and the amount of comonomer X can be 0-30% by weight. Using the above ranges is beneficial for improving the performance of the polymer. The amount of methyl methacrylate is preferably 80-100% by weight, more preferably 90-100% by weight, for example 95-100% by weight, and the amount of comonomer X is preferably 0-20% by weight, more preferably 0-10% by weight, for example 0-5% by weight. For example, based on the total weight of methyl methacrylate and comonomer X, the amount of methyl methacrylate used can be 70 wt%, 72 wt%, 74 wt%, 75 wt%, 76 wt%, 78 wt%, 80 wt%, 82 wt%, 84 wt%, 85 wt%, 86 wt%, 88 wt%, 90 wt%, 91 wt%, 92 wt%, 93 wt%, 94 wt%, 95 wt%, 96 wt%, 97 wt%, 98 wt%, 99 wt%, 100 wt%, or a range of any two or more values, such as 91-100 wt%. For example, based on the total weight of methyl methacrylate and comonomer X, the amount of comonomer X can be 30 wt%, 28 wt%, 26 wt%, 25 wt%, 24 wt%, 22 wt%, 20 wt%, 18 wt%, 16 wt%, 15 wt%, 14 wt%, 12 wt%, 10 wt%, 9 wt%, 8 wt%, 7 wt%, 6 wt%, 5 wt%, 4 wt%, 3 wt%, 2 wt%, 1 wt%, 0 wt%, or a range of any two or more values, such as 9-0 wt%. In this invention, the amount of comonomer X refers to the total amount of all structural units B.

[0092] According to the present invention, in some embodiments, based on the total weight of methyl methacrylate and comonomer X, the amount of the chain transfer agent can be 0.01-1.0 wt%, preferably 0.1-0.8 wt%, for example, it can be 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8 wt%, and any range of any two of the above values. In some embodiments, the use of a chain transfer agent within the above range is beneficial for controlling the weight-average molecular weight of the polymer in the present invention; more preferably, the amount of the chain transfer agent can be 0.1-0.3 wt%.

[0093] According to the present invention, in some embodiments, in step (1), the comonomer X may be selected from the structure shown in Formula 1 and / or Formula 2.

[0094] R1 is selected from C2-C4 straight-chain or branched alkyl groups, and R2 is selected from H or C1-C3 straight-chain or branched alkyl groups.

[0095] In this invention, C2-C4 straight-chain or branched alkyl groups refer to saturated hydrocarbon groups containing 2 to 4 carbon atoms, and these alkyl groups can be straight-chain or branched, for example, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl or tert-butyl.

[0096] In this invention, C1-C3 straight-chain or branched alkyl refers to an alkyl group containing 1 to 3 carbon atoms, and these alkyl groups can be straight-chain or branched, for example, methyl, ethyl, n-propyl or isopropyl.

[0097] The present invention does not particularly limit the relative position of R2 on the benzene ring, and those skilled in the art can select it according to actual needs; for example, R2 can be in the ortho, meta or para position on the benzene ring.

[0098] In this invention, polymerization is carried out using monomers containing the above-mentioned groups and methyl methacrylate, which is more conducive to obtaining products with different performance requirements.

[0099] It should be noted that in this invention, when there is more than one type of comonomer X, there is no particular limitation on the specific amount of each monomer used, as long as the total amount of comonomer X meets the scope of this invention. Furthermore, those skilled in the art can select the amount according to actual needs.

[0100] This invention does not particularly limit the type of chain transfer agent, as long as the weight-average molecular weight of the polymer in this invention can be controlled, and those skilled in the art can select it according to actual needs. In some embodiments, the chain transfer agent may be selected from alkyl mercaptans; preferably, the chain transfer agent may be selected from at least one of n-dodecyl mercaptan, tert-dodecyl mercaptan, n-butanethiol, n-octyl mercaptan, and tert-butanethiol.

[0101] This invention does not particularly limit the type of initiator I, as long as it can initiate the prepolymerization reaction of the polymer. Those skilled in the art can select it according to actual needs. In some embodiments, the initiator I can be selected from free radical initiators, preferably from peroxide initiators and azo initiators. Preferably, the initiator I can be selected from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, lauroyl peroxide, tert-butyl peroxide, diisopropyl percarbonate, cumene hydroperoxide, dicumene peroxide, and cyclohexanone peroxide.

[0102] According to the present invention, preferably, the method may further include cooling methyl methacrylate, optionally comonomer X, chain transfer agent, initiator I and optionally initiator II prior to step (1).

[0103] This invention does not impose particular limitations on the cooling temperature of methyl methacrylate, comonomer X, chain transfer agent, initiator I, and optionally initiator II, as long as the reaction proceeds smoothly. Those skilled in the art can select the appropriate temperature according to actual needs. Preferably, the cooling temperature can be 0-20°C, more preferably 0-15°C, for example, 0-10°C or 10-15°C.

[0104] In this invention, preferably, the cooled raw material is fed into the polymerization reactor, which can realize effective mass and heat transfer of the high-viscosity fluid in bulk polymerization, and is more conducive to precise temperature control.

[0105] In this invention, "optionally comonomer X" means that comonomer X may or may not be added.

[0106] In this invention, initiator II can be added to reactor I together with methyl methacrylate, optionally comonomer X, chain transfer agent, and initiator I. Alternatively, initiator II can be added to reactor II together with the prepolymer solution containing the prepolymer after the prepolymerization stage. Furthermore, initiator II can be added in both reaction stages. This invention does not particularly limit the timing of initiator II's addition, as long as it can initiate the polymerization reaction; those skilled in the art can choose according to actual needs. Preferably, in the method of this invention, initiator II is added to reactor I together with methyl methacrylate, optionally comonomer X, chain transfer agent, and initiator I.

[0107] In this invention, when initiator II is added to reactor I, initiator II does not generate or substantially does not generate free radicals under the prepolymerization reaction conditions carried out in reactor I; that is, initiator II does not decompose or substantially does not decompose under the prepolymerization reaction conditions carried out in reactor I. Therefore, although initiator II is present in the prepolymerization reaction carried out in reactor I, the presence of initiator II has no effect or substantially no effect on the prepolymerization reaction. In this invention, for example, the initiator II does not generate or substantially does not generate free radicals under the prepolymerization reaction conditions carried out in reactor I can be controlled by controlling the conditions of the prepolymerization reaction carried out in reactor I, such as temperature and / or time. For example, the temperature of the prepolymerization reaction carried out in reactor I can be set to a lower temperature to prevent or reduce the generation of free radicals by initiator II. Alternatively, when initiator II can also slowly generate free radicals at the temperature of the prepolymerization reaction carried out in reactor I, the time of the prepolymerization reaction carried out in reactor I (i.e., the prepolymerization time) can be reduced to reduce the amount of decomposition of initiator II in step (1).

[0108] This invention does not particularly limit the mixing method and order of methyl methacrylate, optionally comonomer X, chain transfer agent, initiator I, and optionally initiator II; for example, methyl methacrylate, optionally comonomer X, chain transfer agent, initiator I, and optionally initiator II can be mixed independently with other substances, as long as sufficient contact and mixing are achieved. Those skilled in the art can select according to actual needs. Preferably, in this invention, methyl methacrylate and optionally comonomer X can be mixed evenly in a preparation vessel first, and after cooling, the chain transfer agent, initiator I, and optionally initiator II can be added to the preparation vessel and stirred until completely dissolved. After the substances are dissolved, the mixed solution is injected into a storage tank, and after nitrogen gas is introduced, it is transferred to reaction vessel I.

[0109] The present invention does not particularly limit the types of preparation vessels and storage tanks mentioned above, as long as they can meet the requirements of the present invention. Those skilled in the art can select them according to actual needs.

[0110] The present invention does not particularly limit the stirring method and rate described above, as long as methyl methacrylate, optionally comonomer X, chain transfer agent, initiator I and optionally initiator II can be fully mixed or completely dissolved. Those skilled in the art can select according to actual needs.

[0111] The present invention does not particularly limit the type of reactor I, as long as it enables the reaction described in step (1) to proceed. Those skilled in the art can select one according to actual needs. In some embodiments, any reactor or vessel commonly used for prepolymerization in the polymerization process of methyl methacrylate can be used. In some embodiments, preferably, the reactor I described in step (1) is a vertical reactor or a horizontal reactor, preferably a horizontal self-cleaning reactor or a vertical self-cleaning reactor.

[0112] The vertical or horizontal reactor I of the present invention, such as the horizontal self-cleaning reactor I, may have a high-torque stirring paddle, which can realize effective mass and heat transfer of high-viscosity fluids in bulk polymerization. Furthermore, the stirring paddle and jacket of the vertical or horizontal reactor I, such as the horizontal self-cleaning reactor, may be equipped with a circulating heat transfer medium, which is beneficial to achieve rapid heat transfer over a large area and precise temperature control, and avoids gelation.

[0113] The vertical or horizontal reactor I of the present invention may have a high-torque stirring paddle to enhance mass and heat transfer, and a gas phase condenser may be installed at the upper end of the polymerization reactor to achieve precise temperature control of bulk polymerization and improve the controllability of polymerization.

[0114] The present invention does not particularly limit the rate at which methyl methacrylate and optionally comonomer X are introduced into reactor I, as long as the reaction proceeds smoothly. Those skilled in the art can select the appropriate rate according to actual needs. In some embodiments, preferably, the rate at which methyl methacrylate and comonomer X are introduced into reactor I can be 0.1-1 L / min, and the rate at which they are introduced into reactor I can be 0-1 L / min.

[0115] It should be noted that the present invention does not particularly limit the rate at which the chain transfer agent, initiator I, and optionally initiator II are introduced into reactor I, and those skilled in the art can select them according to actual needs. According to some embodiments of the present invention, preferably, the chain transfer agent, initiator I, and optionally initiator II are mixed evenly with methyl methacrylate and optionally comonomer X and then introduced into reactor I at a rate of 0.1-1 L / min.

[0116] This invention does not particularly limit the method of introduction. The materials can be fed independently through multiple pipelines at the aforementioned speed, or they can be mixed and then fed through a single pipeline. Those skilled in the art can choose according to actual needs. In some embodiments, preferably, this invention uses a pump to introduce the chain transfer agent, initiator I, and optionally initiator II together with methyl methacrylate and optionally comonomer X into reactor I through a single pipeline.

[0117] This invention does not impose any particular limitation on the type of pump; any pump that meets the requirements of this invention is acceptable. Those skilled in the art can select the appropriate pump based on actual needs.

[0118] The above-mentioned rate is more conducive to the full contact of methyl methacrylate, optional comonomer X, chain transfer agent, initiator I and optional initiator II, resulting in a stable reaction and improved overall performance of methyl methacrylate polymer.

[0119] According to the present invention, preferably, the prepolymerization reaction in step (1) is carried out under stirring conditions.

[0120] The present invention does not particularly limit the stirring rate of the prepolymerization reaction, as long as it can ensure that the substances in the prepolymerization reaction react fully. Those skilled in the art can select the stirring rate according to actual needs. In some embodiments, preferably, the stirring rate of the prepolymerization reaction in step (1) can be 2-100 rpm, for example, 5-20 rpm or 20-100 rpm.

[0121] According to the present invention, in some embodiments, preferably, the conditions of the prepolymerization reaction may include: a reaction temperature of 80-130°C, preferably 85-125°C, and / or a reaction time of 10-90 minutes, preferably 10-60 minutes. For example, the reaction temperature of the prepolymerization reaction may be 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, or any range of two of the above values, such as 80-125°C. For example, the reaction time of the prepolymerization reaction may be 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, or any range of two of the above values, such as 15-50 minutes.

[0122] The polymerization temperature described above in this invention enables stable polymerization of methyl methacrylate and avoids gelation.

[0123] According to the present invention, in some embodiments, preferably, the temperature fluctuation of the prepolymerization reaction is less than 3°C.

[0124] The polymerization temperature described above in this invention enables the stable polymerization of methyl methacrylate.

[0125] According to the present invention, in some embodiments, preferably, the yield of the prepolymer in the prepolymerization reaction in step (1) is 20-40% by weight, which is conducive to avoiding the problem of a sharp increase in the viscosity of the polymer system in the final polymerization reaction; more preferably, it is 25-35% by weight, which is conducive to the final polymerization reaction.

[0126] In this invention, the yield of the prepolymer is calculated by precipitation; the mass of the prepolymer solution is m0, the mass of the precipitated polymer after drying is m1, and the yield of the prepolymer is (m1 / m0)×100%.

[0127] In this invention, the prepolymer solution refers to the solution after the prepolymerization reaction.

[0128] The yield of the prepolymer in the prepolymerization reaction of this invention is within the above-mentioned range, which is more conducive to the final polymerization reaction in continuous polymerization.

[0129] The present invention does not particularly limit the type of reactor II, as long as it enables the reaction described in step (2) to proceed. Those skilled in the art can select one according to actual needs. In some embodiments, any reactor or vessel commonly used for the final polymerization in the polymerization process of methyl methacrylate polymers can be used. Preferably, reactor II described in step (2) is a vertical or horizontal reactor, preferably a horizontal self-cleaning reactor.

[0130] The horizontal reactor II used in this invention, such as a horizontal self-cleaning reactor, can be equipped with a high-torque stirring paddle, which can realize effective mass and heat transfer of high-viscosity fluids in bulk polymerization. Furthermore, the stirring paddle and jacket of the horizontal reactor II, such as the horizontal self-cleaning reactor, can be equipped with circulating heat transfer media, which is more conducive to achieving rapid heat transfer over a large area and precise temperature control, avoiding gel formation and preventing automatic acceleration of polymerization.

[0131] The present invention does not impose a particular limitation on the rate at which the prepolymer solution containing the prepolymer is introduced into reactor II in step (2), as long as the reaction in step (2) proceeds smoothly. Those skilled in the art can select the appropriate rate according to actual needs. In some embodiments, preferably, the rate at which the prepolymer solution containing the prepolymer is introduced into reactor II can be 0.1-1 L / min.

[0132] The method of introducing material into reactor II in step (2) of this invention is the same as the method of introducing material into reactor I in step (1) above, and will not be repeated here.

[0133] It should be noted that when initiator II is added in step (2), the present invention does not particularly limit the rate at which initiator II is introduced into reactor II, and those skilled in the art can select the rate according to actual needs. In some embodiments, preferably, in the present invention, initiator II can be introduced into reactor II together with the prepolymer solution containing the prepolymer through the same pipeline at a rate of 0.1-1 L / min.

[0134] According to the present invention, preferably, the final polymerization reaction in step (2) is carried out under stirring conditions.

[0135] The present invention does not particularly limit the stirring rate of the final polymerization reaction, as long as it allows the substances in step (2) to react fully. Those skilled in the art can select the stirring rate according to actual needs. In some embodiments, preferably, the stirring rate of the final polymerization reaction in step (2) is 2-30 rpm, more preferably 5-20 rpm.

[0136] According to the present invention, in some embodiments, preferably, the conditions for the final polymerization reaction may include: a reaction temperature of 130-190°C, preferably 135-185°C, for example 135-170°C or 140-180°C, and / or a reaction time of 10-90 minutes, preferably 15-60 minutes, for example 30-50 minutes. For example, the reaction temperature of the final polymerization reaction may be 135°C, 140°C, 145°C, 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, or any range of two of the above values, for example 135-180°C. For example, the reaction time of the final polymerization reaction can be 10 minutes, 15 minutes, 20 minutes, 25 minutes, 30 minutes, 35 minutes, 40 minutes, 45 minutes, 50 minutes, 55 minutes, 60 minutes, 65 minutes, 70 minutes, 75 minutes, 80 minutes, 85 minutes, 90 minutes, or any range of two of the above values, such as 15-55 minutes.

[0137] According to the present invention, in some embodiments, preferably, the temperature fluctuation of the final polymerization reaction is less than 3°C.

[0138] According to the present invention, the temperature of the final polymerization reaction is higher than the temperature of the prepolymerization reaction. In some embodiments, the temperature of the final polymerization reaction may be 20-90°C higher than the temperature of the prepolymerization reaction, preferably 20°C to 80°C higher. For example, the temperature of the final polymerization reaction may be 20°C, 25°C, 30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, or 90°C higher than the temperature of the prepolymerization reaction, or any range of two of the above values, such as 25-80°C. The polymerization temperature used in the present invention is more conducive to the stable polymerization of methyl methacrylate; by activating the multifunctional initiator II at the stated temperature, the polymerization of methyl methacrylate initiated by initiator II can be achieved, resulting in a methyl methacrylate polymer with uniform molecular weight, low isotacticity, and good processability.

[0139] In some embodiments of the present invention, steps (1) and (2) are performed in the presence of initiator II. In some embodiments of the present invention, the reaction temperature of the prepolymerization reaction in step (1) is 80-130°C, preferably 85-125°C, and the final polymerization reaction temperature is higher than the prepolymerization reaction temperature, preferably 20-90°C higher than the prepolymerization reaction temperature, and more preferably 20°C to 80°C higher than the prepolymerization reaction temperature.

[0140] The present invention does not particularly limit the type of protective gas used in steps (1) and / or (2), as long as it meets the requirements of the present invention. Those skilled in the art can select according to actual needs. In some embodiments, the protective gas is preferably nitrogen or an inert gas. For inert gases, those commonly used in the field of polymerization can be used, including, for example, helium, neon, argon, etc.

[0141] This invention improves polymer performance by using a protective gas to remove dissolved oxygen from the system.

[0142] According to the present invention, in some embodiments, preferably, the method may further include discharging, devolatilizing and extruding the methyl methacrylate polymer after the final polymerization reaction.

[0143] In the art, it is known to discharge, devolatilize, and extrude methyl methacrylate polymers after polymerization. The present invention does not particularly limit the equipment used for discharging, devolatilizing, and extruding the polymer; those skilled in the art can select the appropriate equipment according to actual needs. According to some embodiments of the present invention, preferably, the discharging, devolatilizing, and extrusion of the polymer can be carried out in a screw extruder.

[0144] According to the present invention, preferably, the discharge temperature can be 165-200℃, more preferably 170-190℃.

[0145] This invention does not impose a particular limitation on the discharge rate, which can be adjusted according to the size of the reactor, and those skilled in the art can select it according to actual needs. In some embodiments, preferably, the discharge rate can be 5-25 rpm, more preferably 8-20 rpm.

[0146] According to the present invention, preferably, the devolatilization temperature can be 185-245℃, more preferably 190-230℃. According to the present invention, preferably, the devolatilization rate can be 80-200 rpm, more preferably 80-180 rpm. According to the present invention, preferably, the devolatilization pressure can be less than or equal to 100 Pa, more preferably less than or equal to 25 Pa, for example, it can be equal to or less than 20 Pa, for example, the devolatilization pressure is less than or equal to 10 Pa.

[0147] This invention does not impose any particular limitation on the number of temperature settings during the devolatilization process, as long as the volatile substances in the polymerization reaction process can be effectively removed. Those skilled in the art can select the appropriate settings according to actual needs.

[0148] The present invention employs the above-mentioned discharge temperature and rate, as well as devolatilization temperature and rate, which are more conducive to obtaining pure polymers.

[0149] The present invention may further include stretching, cooling, pelletizing and drying after discharging, devolatilizing and extruding the methyl methacrylate polymer to obtain methyl methacrylate polymer granules.

[0150] In the art, operations such as stretching, cooling, pelletizing, and drying are known. This invention does not particularly limit the equipment and temperature for stretching, cooling, pelletizing, and drying, as long as the methyl methacrylate polymer pellets described in this invention can be obtained. Those skilled in the art can select the appropriate equipment according to actual needs.

[0151] In some embodiments of the present invention, the initiator II is selected from one or more of the following:

[0152] The third aspect of the present invention provides a methyl methacrylate polymer prepared by the preparation method described in the second aspect above; preferably, the methyl methacrylate polymer prepared is the methyl methacrylate polymer of the first aspect.

[0153] The fourth aspect of the present invention provides the use of the methyl methacrylate polymer described in the first or third aspect above in at least one of liquid crystal displays, optical materials, automotive headlights, and electronic products.

[0154] The present invention will be described in detail below through embodiments.

[0155] Unless otherwise specified, all examples and comparative examples below are based on conventional methods; and all reagents and materials used, unless otherwise specified, are commercially available and / or prepared using methods known in the art.

[0156] Methyl methacrylate, Shanghai Maclean Biochemical Technology Co., Ltd., with a purity greater than 99.5%.

[0157] In the following examples and comparative examples, the contents of structural unit A and structural unit B were determined by measuring the proton NMR spectra using a Swiss Bruker AV 300 NMR spectrometer and calculated based on the integral area of ​​the proton NMR spectra of the groups in structural unit A and structural unit B (-OCH3 in structural unit A and benzene ring or -OCH2- in structural unit B).

[0158] In the following examples and comparative examples, the yield of the prepolymer from the prepolymerization reaction was calculated by precipitation. The mass of the prepolymer solution was m0, which was precipitated with ethanol, washed three times with ethanol, and then dried in a vacuum oven at 60°C to constant weight, with the mass being m1. The yield of the prepolymer was calculated as (m1 / m0) × 100%.

[0159] In the following examples and comparative examples, gel permeation chromatography (PL-GPC220) was used to measure the weight-average molecular weight and its distribution of the polymers. Tetrahydrofuran was used as the solvent, the tests were conducted at room temperature, and polystyrene was used as the standard.

[0160] In the following examples and comparative examples, the glass transition temperature T of the polymers was measured using a differential scanning calorimeter (DSC8500; PerkinElmer). g The heating / cooling rate is 10℃ / min, under nitrogen atmosphere protection.

[0161] In the following examples and comparative examples, the transmittance of the polymer was determined according to ISO 13468-2:2021 and the haze of the polymer was determined according to ISO 14782:2021.

[0162] In the following examples and comparative examples, the polymer melt index was tested according to ISO 1133-1:2022 at 230°C and 3.8 kg.

[0163] In the following examples and comparative examples, the proton NMR spectra of the polymers were measured using a Bruker AV 300 NMR spectrometer (Switzerland). The isotacticity, syndiotacticity, and residual monomer content of the polymers were calculated based on the integral area of ​​the proton NMR spectra. (See Anionic polymerization of methyl methacrylate and chain-end modification via terminal-selective transesterification with bulky zincate [J], Tomohiro Hirano et al, European Polymer Journal, 201(2023)112581)

[0164] In the following examples and comparative examples, the yield of the final polymer during and after the final polymerization reaction in this invention was calculated by precipitation. The polymer solution mass was taken out as m2, precipitated with ethanol, washed with ethanol 3 times, and then the polymer was dried in a vacuum oven at 60°C to constant weight, and the mass was m3. The yield of the final polymer = (m3 / m2)×100%.

[0165] Example A1

[0166] 100 kg of methyl methacrylate was metered into the preparation vessel by a pump, stirred and mixed evenly, and then cooled to 12°C.

[0167] Add 0.25 kg of chain transfer agent n-dodecyl mercaptan, 0.20 kg of benzoyl peroxide, and 0.5 kg of multifunctional initiator II to the preparation vessel, and stir until completely dissolved;

[0168] The solution in the preparation vessel is injected into the monomer storage tank by a pump metering, and high-purity nitrogen gas is blown in through the bottom tube in the tank;

[0169] The solution in the monomer storage tank is continuously injected into the horizontal self-cleaning reactor I at a rate of 0.6 L / min by a pump. The reactor temperature is 100℃, the stirring rate is 8 rpm, and the material residence time is 30 min. Then, the solution is continuously pumped from reactor I to the horizontal self-cleaning reactor II at a rate of 0.6 L / min to continue polymerization. The polymerization temperature is 140℃, the stirring rate is 5 rpm, and the material residence time is 30 min.

[0170] The material is continuously fed into the twin-screw devolatilization section via the discharge screw. The discharge screw temperature is 175℃, the discharge screw speed is 10rpm, the six devolatilization temperatures are 190℃, 200℃, 210℃, 210℃, 215℃ and 220℃ respectively, the twin-screw devolatilization speed is 110rpm, and the devolatilization section pressure is less than 20Pa.

[0171] After devolatilization, the methyl methacrylate polymer granules were obtained by extrusion through a twin-screw extruder, forming, cooling, pelletizing, and drying. The performance test results are shown in Tables A1 and A2.

[0172] Example A2

[0173] 95 kg of methyl methacrylate and 5 kg of styrene (R2 is H in Formula 2) were metered into the preparation vessel by a pump, stirred and mixed evenly, and then cooled to 10°C.

[0174] Add 0.1 kg of chain transfer agent tert-dodecyl mercaptan, 0.6 kg of azobisisobutyronitrile, and 0.2 kg of multifunctional initiator II to the preparation vessel, and stir until completely dissolved;

[0175] The solution in the preparation vessel is injected into the monomer storage tank by a pump metering, and high-purity nitrogen gas is blown in through the bottom tube in the tank;

[0176] The solution in the monomer storage tank is continuously injected into the horizontal self-cleaning reactor I at a rate of 0.3 L / min by a pump. The temperature inside the reactor is 90℃, the stirring rate is 12 rpm, and the material residence time is 40 min. Then, the solution is continuously sent from reactor I to the horizontal self-cleaning reactor II at a rate of 0.3 L / min to continue polymerization. The polymerization temperature is 170℃, the stirring rate is 14 rpm, and the material residence time is 20 min.

[0177] The material is continuously fed into the twin-screw devolatilization section via the discharge screw. The discharge screw temperature is 190℃, the discharge screw speed is 13rpm, the six devolatilization temperatures are 200℃, 205℃, 210℃, 215℃, 215℃ and 220℃ respectively, the twin-screw devolatilization speed is 80rpm, and the devolatilization section pressure is less than 20Pa.

[0178] After devolatilization, the methyl methacrylate polymer granules were obtained by extrusion through a twin-screw extruder, forming, cooling, pelletizing, and drying. The performance test results are shown in Tables A1 and A2.

[0179] Example A3

[0180] 90 kg of methyl methacrylate and 10 kg of styrene (R2 is H in Formula 2) are metered into the preparation vessel by a pump, stirred and mixed evenly, and then cooled to 12°C.

[0181] Add 0.3 kg of chain transfer agent n-dodecyl mercaptan, 0.30 kg of benzoyl peroxide, and 0.4 kg of multifunctional initiator II to the preparation vessel, and stir until completely dissolved;

[0182] The solution in the preparation vessel is injected into the monomer storage tank by a pump metering, and high-purity nitrogen gas is blown in through the bottom tube in the tank;

[0183] The solution in the monomer storage tank is continuously injected into the horizontal self-cleaning reactor I at a rate of 0.6 L / min by a pump. The reactor temperature is 100℃, the stirring rate is 8 rpm, and the material residence time is 30 min. Then, the solution is continuously pumped from reactor I to the horizontal self-cleaning reactor II at a rate of 0.6 L / min to continue polymerization. The polymerization temperature is 140℃, the stirring rate is 8 rpm, and the material residence time is 30 min.

[0184] The material is continuously fed into the twin-screw devolatilization section via the discharge screw. The discharge screw temperature is 175℃, the discharge screw speed is 10rpm, the six devolatilization temperatures are 190℃, 200℃, 210℃, 210℃, 215℃ and 220℃ respectively, the twin-screw devolatilization speed is 110rpm, and the devolatilization section pressure is less than 20Pa.

[0185] After devolatilization, the methyl methacrylate polymer granules were obtained by extrusion through a twin-screw extruder, forming, cooling, pelletizing, and drying. The performance test results are shown in Tables A1 and A2.

[0186] Example A4

[0187] 85 kg of methyl methacrylate and 15 kg of tert-butyl methacrylate (R1 in Formula 1 is tert-butyl) were metered into the preparation vessel by a pump, stirred and mixed evenly, and then cooled to 20°C.

[0188] Add 0.2 kg of chain transfer agent dodecyl mercaptan, 0.6 kg of tert-butyl peroxide, and 0.3 kg of multifunctional initiator II to the preparation vessel, and stir until completely dissolved;

[0189] The solution in the preparation vessel is injected into the monomer storage tank by a pump metering, and high-purity nitrogen gas is blown in through the bottom tube in the tank;

[0190] The solution in the monomer storage tank is continuously injected into the horizontal self-cleaning reactor I at a rate of 0.4 L / min by a pump. The reactor temperature is 110℃, the stirring rate is 20 rpm, and the material residence time is 35 min. Then, the solution is continuously sent from reactor I to the horizontal self-cleaning reactor II at a rate of 0.4 L / min to continue polymerization. The polymerization temperature is 130℃, the stirring rate is 20 rpm, and the material residence time is 40 min.

[0191] The material is continuously fed into the twin-screw devolatilization section via the discharge screw. The discharge screw temperature is 170℃, the discharge screw speed is 20rpm, the six devolatilization temperatures are 190℃, 195℃, 200℃, 210℃, 220℃ and 230℃ respectively, the twin-screw devolatilization speed is 180rpm, and the devolatilization section pressure is less than 20Pa.

[0192] After devolatilization, the methyl methacrylate polymer granules were obtained by extrusion through a twin-screw extruder, forming, cooling, pelletizing, and drying. The performance test results are shown in Tables A1 and A2.

[0193] Example A5

[0194] 70 kg of methyl methacrylate and 30 kg of butyl methacrylate (R1 in Formula 1 is butyl) were metered into the preparation vessel by a pump, stirred and mixed evenly, and then cooled to 0°C.

[0195] Add 0.8 kg of chain transfer agent n-octyl mercaptan, 0.1 kg of azobisisobutyronitrile, and 1.5 kg of multifunctional initiator II to the preparation vessel, and stir until completely dissolved;

[0196] The solution in the preparation vessel is injected into the monomer storage tank by a pump metering, and high-purity nitrogen gas is blown in through the bottom tube in the tank;

[0197] The solution in the monomer storage tank is continuously injected into the horizontal self-cleaning reactor I at a rate of 0.8 L / min by a pump. The temperature inside the reactor is 130℃, the stirring rate is 5 rpm, and the material residence time is 20 min. Then, the solution is continuously sent from reactor I to the horizontal self-cleaning reactor II at a rate of 0.8 L / min to continue polymerization. The polymerization temperature is 152℃, the stirring rate is 5 rpm, and the material residence time is 25 min.

[0198] The material is continuously fed into the twin-screw devolatilization section via the discharge screw. The discharge screw temperature is 175℃, the discharge screw speed is 8rpm, the six devolatilization temperatures are 190℃, 200℃, 205℃, 210℃, 215℃ and 220℃ respectively, the twin-screw devolatilization speed is 160rpm, and the devolatilization section pressure is less than 20Pa.

[0199] After devolatilization, the methyl methacrylate polymer granules were obtained by extrusion through a twin-screw extruder, forming, cooling, pelletizing, and drying. The performance test results are shown in Tables A1 and A2.

[0200] Example A6

[0201] 80 kg of methyl methacrylate and 20 kg of ethyl methacrylate (R1 in Formula 1 is ethyl) were metered into the preparation vessel by a pump, stirred and mixed evenly, and then cooled to 5°C.

[0202] Add 0.35 kg of chain transfer agent n-butanethiol, 0.3 kg of dicumyl peroxide, and 0.8 kg of multifunctional initiator II to the preparation vessel, and stir until completely dissolved;

[0203] The solution in the preparation vessel is injected into the monomer storage tank by a pump metering, and high-purity nitrogen gas is blown in through the bottom tube in the tank;

[0204] The solution in the monomer storage tank is continuously injected into the horizontal self-cleaning reactor I at a rate of 1L / min by a pump. The temperature inside the reactor is 120℃, the stirring rate is 15rpm, and the material residence time is 15min. Then, the solution is continuously sent from reactor I to the horizontal self-cleaning reactor II at a rate of 1L / min to continue polymerization. The polymerization temperature is 160℃, the stirring rate is 14rpm, and the material residence time is 18min.

[0205] The material is continuously fed into the twin-screw devolatilization section via the discharge screw. The discharge screw temperature is 180℃, the discharge screw speed is 16rpm, the six devolatilization temperatures are 190℃, 200℃, 210℃, 215℃, 220℃ and 225℃ respectively, the twin-screw devolatilization speed is 135rpm, and the pressure in the devolatilization section is less than 20Pa.

[0206] After devolatilization, the methyl methacrylate polymer granules were obtained by extrusion through a twin-screw extruder, forming, cooling, pelletizing, and drying. The performance test results are shown in Tables A1 and A2.

[0207] Example A7

[0208] The method of Example A1 was repeated, except that the amount of multifunctional initiator II added was 0.1 kg. The performance test results are shown in Tables A1 and A2.

[0209] Example A8

[0210] The method of Example A1 was repeated, except that 97 kg of methyl methacrylate and 3 kg of styrene were used. The performance test results are shown in Tables A1 and A2.

[0211] Comparative Example A1

[0212] The properties of methyl methacrylate polymer with the brand name Mitsubishi VH001 were tested, and the results are shown in Tables A1 and A2.

[0213] Comparative Example A2

[0214] The method of Example A1 was repeated, except that initiator II was replaced with an equal amount of cumene hydrogen peroxide. The performance test results are shown in Tables A1 and A2.

[0215] Comparative Example A3

[0216] The method of Example A1 was repeated, except that initiator II was not added. The performance test results are shown in Tables A1 and A2.

[0217] Comparative Example A4

[0218] The method of Example A1 was repeated, except that the prepolymerization temperature was 140°C, which was the same as the final polymerization temperature. The performance test results are shown in Tables A1 and A2.

[0219] In Examples A1-A8 and Comparative Example A4, the multifunctional initiator II was the following compound (Chongqing Futeng Pharmaceutical Chemical Co., Ltd.):

[0220] Table A1

[0221] Table A2

[0222] The monomer residue in Table A2 refers to the content of residual monomers in the methyl methacrylate polymer.

[0223] As can be seen from the results in Tables A1 and A2, compared with the comparative example, the polymer of the present invention has significant advantages in terms of molecular characteristics, exhibiting higher uniformity in weight-average molecular weight and lower isotacticity, and the polymer of the present invention exhibits superior processing performance.

[0224] Example B1

[0225] 100 kg of methyl methacrylate was metered into the preparation vessel by a pump, stirred and mixed evenly, and then cooled to 10°C.

[0226] Add 0.2 kg of chain transfer agent n-dodecyl mercaptan, 0.2 kg of benzoyl peroxide, and 0.3 kg of initiator II to the preparation vessel, and stir until completely dissolved;

[0227] The solution in the preparation vessel is injected into the monomer storage tank by a pump metering, and high-purity nitrogen gas is blown in through the bottom tube in the tank;

[0228] The solution in the monomer storage tank is continuously injected into the vertical high-torque polymerization reactor at a rate of 0.5 L / min by a pump. The reactor temperature is 105℃, the stirring rate is 60 rpm, and the material residence time is 20 min. Then, it is continuously fed from the bottom of the reactor into the horizontal self-cleaning polymerization reactor at a rate of 0.5 L / min to continue polymerization. The polymerization temperature is 145℃, the stirring rate is 10 rpm, and the material residence time is 30 min.

[0229] The material is continuously fed into the twin-screw devolatilization section via the discharge screw. The discharge screw temperature is 180℃, the discharge screw speed is 10rpm, the six devolatilization temperatures are 190℃, 200℃, 200℃, 210℃, 210℃ and 220℃ respectively, the twin-screw devolatilization speed is 140rpm, and the devolatilization section pressure is less than or equal to 10Pa.

[0230] After devolatilization, the methyl methacrylate polymer granules were obtained by extrusion through a twin-screw extruder, forming, cooling, pelletizing, and drying. The performance test results are shown in Tables B1 and B2.

[0231] Example B2

[0232] 80 kg of methyl methacrylate and 20 kg of tert-butyl methacrylate (R1 in Formula 1 is tert-butyl) were metered into the preparation vessel by a pump, stirred and mixed evenly, and then cooled to 20°C.

[0233] Add 0.8 kg of chain transfer agent n-dodecyl mercaptan, 0.05 kg of lauroyl peroxide, and 1.2 kg of initiator II to the preparation vessel, and stir until completely dissolved;

[0234] The solution in the preparation vessel is injected into the monomer storage tank by a pump metering, and high-purity nitrogen gas is blown in through the bottom tube in the tank;

[0235] The solution in the monomer storage tank is continuously injected into the vertical high-torque polymerization reactor at a rate of 0.2 L / min by a pump. The reactor temperature is 100℃, the stirring rate is 40 rpm, and the material residence time is 30 min. Then, it is continuously fed from the bottom of the reactor into the horizontal self-cleaning polymerization reactor at a rate of 0.2 L / min to continue polymerization. The polymerization temperature is 160℃, the stirring rate is 16 rpm, and the material residence time is 40 min.

[0236] The material is continuously fed into the twin-screw devolatilization section via the discharge screw. The discharge screw temperature is 190℃, the discharge screw speed is 18rpm, the six devolatilization temperatures are 190℃, 200℃, 210℃, 210℃, 210℃ and 215℃ respectively, the twin-screw devolatilization speed is 120rpm, and the devolatilization section pressure is less than or equal to 10Pa.

[0237] After devolatilization, the methyl methacrylate polymer granules were obtained by extrusion through a twin-screw extruder, forming, cooling, pelletizing, and drying. The performance test results are shown in Tables B1 and B2.

[0238] Example B3

[0239] 97.5 kg of methyl methacrylate and 2.5 kg of butyl methacrylate (R1 in Formula 1 is butyl) were metered into the preparation vessel by a pump, stirred and mixed evenly, and then cooled to 0°C.

[0240] Add 0.05 kg of chain transfer agent n-butanethiol, 1 kg of azobisisobutyronitrile, and 0.1 kg of initiator II to the preparation vessel, and stir until completely dissolved;

[0241] The solution in the preparation vessel is injected into the monomer storage tank by a pump metering, and high-purity nitrogen gas is blown in through the bottom tube in the tank;

[0242] The solution in the monomer storage tank is continuously injected into the vertical high-torque polymerization reactor at a rate of 0.8 L / min by a pump. The reactor temperature is 120°C, the stirring rate is 85 rpm, and the material residence time is 25 min. Then, it is continuously fed from the bottom of the reactor into the horizontal self-cleaning polymerization reactor at a rate of 0.8 L / min to continue polymerization. The polymerization temperature is 170°C, the stirring rate is 18 rpm, and the material residence time is 25 min.

[0243] The material is continuously fed into the twin-screw devolatilization section via the discharge screw. The discharge screw temperature is 185℃, the discharge screw speed is 16rpm, the six devolatilization temperatures are 190℃, 200℃, 210℃, 220℃, 220℃ and 230℃ respectively, the twin-screw devolatilization speed is 150rpm, and the devolatilization section pressure is less than or equal to 10Pa.

[0244] After devolatilization, the methyl methacrylate polymer granules were obtained by extrusion through a twin-screw extruder, forming, cooling, pelletizing, and drying. The performance test results are shown in Tables B1 and B2.

[0245] Example B4

[0246] 95 kg of methyl methacrylate and 5 kg of styrene (R2 is H in Formula 2) were metered into the preparation vessel by a pump, stirred and mixed evenly, and then cooled to 15°C.

[0247] Add 0.3 kg of chain transfer agent tert-dodecyl mercaptan, 0.25 kg of diisopropyl peroxide dicarbonate, and 0.4 kg of initiator II to the preparation vessel, and stir until completely dissolved;

[0248] The solution in the preparation vessel is injected into the monomer storage tank by a pump metering, and high-purity nitrogen gas is blown in through the bottom tube in the tank;

[0249] The solution in the monomer storage tank is continuously injected into the vertical high-torque polymerization reactor at a rate of 0.6 L / min by a pump. The reactor temperature is 130℃, the stirring rate is 35 rpm, and the material residence time is 15 min. Then, it is continuously fed from the bottom of the reactor into the horizontal self-cleaning polymerization reactor at a rate of 0.6 L / min to continue polymerization. The polymerization temperature is 150℃, the stirring rate is 12 rpm, and the material residence time is 35 min.

[0250] The material is continuously fed into the twin-screw devolatilization section via the discharge screw. The discharge screw temperature is 185℃, the discharge screw speed is 11 rpm, the six devolatilization temperatures are 190℃, 200℃, 210℃, 210℃, 220℃ and 225℃ respectively, the twin-screw devolatilization speed is 160 rpm, and the devolatilization section pressure is less than or equal to 10 Pa.

[0251] After devolatilization, the methyl methacrylate polymer granules were obtained by extrusion through a twin-screw extruder, forming, cooling, pelletizing, and drying. The performance test results are shown in Tables B1 and B2.

[0252] Example B5

[0253] 90 kg of methyl methacrylate and 10 kg of butyl methacrylate (R1 in Formula 1 is butyl) were metered into the preparation vessel by a pump, stirred and mixed evenly, and then cooled to 8°C.

[0254] Add 0.4 kg of chain transfer agent n-octyl mercaptan, 0.4 kg of cyclohexanone peroxide, and 0.6 kg of initiator II to the preparation vessel, and stir until completely dissolved;

[0255] The solution in the preparation vessel is injected into the monomer storage tank by a pump metering, and high-purity nitrogen gas is blown in through the bottom tube in the tank;

[0256] The solution in the monomer storage tank is continuously injected into the vertical high-torque polymerization reactor at a rate of 0.9 L / min by a pump. The reactor temperature is 115℃, the stirring rate is 70 rpm, and the material residence time is 20 min. Then, it is continuously fed from the bottom of the reactor into the horizontal self-cleaning polymerization reactor at a rate of 0.9 L / min to continue polymerization. The polymerization temperature is 180℃, the stirring rate is 20 rpm, and the material residence time is 20 min.

[0257] The material is continuously fed into the twin-screw devolatilization section via the discharge screw. The discharge screw temperature is 190℃, the discharge screw speed is 15rpm, the six devolatilization temperatures are 200℃, 200℃, 200℃, 210℃, 210℃ and 220℃ respectively, the twin-screw devolatilization speed is 145rpm, and the devolatilization section pressure is less than or equal to 10Pa.

[0258] After devolatilization, the methyl methacrylate polymer granules were obtained by extrusion through a twin-screw extruder, forming, cooling, pelletizing, and drying. The performance test results are shown in Tables B1 and B2.

[0259] Example B6

[0260] The method of Example B1 was repeated, except that the amount of initiator II added was 0.02 kg. The performance test results are shown in Tables B1 and B2.

[0261] Example B7

[0262] The method of Example B1 was repeated, except that samples were taken at a sampling port reserved in the middle of the horizontal self-cleaning polymerization reactor at 20 min, 40 min, 60 min, 80 min, 100 min, and 120 min of polymerization, respectively, to test the process yield in the final polymerization reactor. The test results were 79.8%, 80.2%, 79.9%, 79.1%, 80.3%, and 80.2%, respectively. This indicates that initiator II can decompose into free radicals in an orderly manner, the polymerization reaction is stable, and the polymerization rate is controllable.

[0263] Example B8

[0264] The method of Example B3 was repeated, except that samples were taken at a sampling port reserved in the middle of the horizontal self-cleaning polymerization reactor at 20 min, 40 min, 60 min, 80 min, 100 min, and 120 min of polymerization, respectively, to test the process yield in the final polymerization reactor. The test results were 76.2%, 76.3%, 76.1%, 76.1%, 76.3%, and 76.1%, respectively. This indicates that initiator II can decompose into free radicals in an orderly manner, the polymerization reaction is stable, and the polymerization rate is controllable.

[0265] Comparative Example B1

[0266] The method of Example B1 was repeated, except that initiator II was replaced with an equal amount of benzoyl peroxide. The performance test results are shown in Tables B1 and B2.

[0267] Comparative Example B2

[0268] The method of Example B1 was repeated, except that initiator II was not added, and samples were taken at a sampling port reserved in the middle of the horizontal self-cleaning polymerization reactor at 20 min, 40 min, 60 min, 80 min, 100 min, and 120 min of polymerization. The process yield in the final polymerization reactor was tested, and the results were 44.7%, 38.8%, 48.5%, 40.7%, 42.5%, and 45.6%, respectively. This indicates that without initiator II, the conversion rate is low, the polymerization reaction is unstable, the polymerization rate is uncontrollable, and local overheating occurs. The performance test results are shown in Tables B1 and B2.

[0269] Comparative Example B3

[0270] The method of Example B1 was repeated, except that the polymerization temperature in the vertical high-torque polymerization reactor was 70°C and the polymerization temperature in the horizontal self-cleaning polymerization reactor was 200°C. The performance test results are shown in Tables B1 and B2.

[0271] Comparative Example B4

[0272] The method of Example B1 was repeated, except that initiator II was replaced with 1,1-di-tert-butylcyclohexane peroxide. The performance test results are shown in Tables B1 and B2.

[0273] Comparative Example B5

[0274] The method of Example B1 was repeated, except that 10 kg of toluene was added to the preparation vessel. The performance test results are shown in Tables B1 and B2.

[0275] Comparative Example B6

[0276] The method of Example B1 was repeated, except that the horizontal self-cleaning polymerization reactor was replaced with a twin-screw extruder (Jiangsu Chengmeng Equipment Co., Ltd., model: TSD36). Performance test results are shown in Tables B1 and B2.

[0277] Comparative Example B7

[0278] The method of Example B1 was repeated, except that the prepolymerization temperature was 145°C, which was the same as the final polymerization temperature. The performance test results are shown in Tables B1 and B2.

[0279] Comparative Example B8

[0280] The method of Example B1 was repeated, except that only initiator II was added. The performance test results are shown in Tables B1 and B2.

[0281] In Examples B1-B8 and Comparative Examples B3, B5-B8, the multifunctional initiator II was the following compound (Nouryon Chemicals (Ningbo) Co., Ltd.):

[0282] Table B1

[0283] Table B2

[0284] The monomer residue in Table B2 refers to the content of residual monomers in the methyl methacrylate polymer.

[0285] As can be seen from the results in Tables B1 and B2, the polymers prepared in the embodiments of the present invention significantly outperform the comparative examples in terms of performance. Compared to the comparative examples, the polymers of the present invention have significant advantages in molecular characteristics, exhibiting higher uniformity in weight-average molecular weight and lower isotacticity, resulting in superior processing performance. During the polymerization process, the method of the present invention demonstrates excellent control capabilities, effectively ensuring that the reaction proceeds along a precise and stable path. Simultaneously, it greatly enhances mass and heat transfer efficiency, promoting rapid and uniform distribution and exchange of matter and energy within the reaction system, creating more ideal environmental conditions for the polymerization reaction, effectively reducing the risk of gelation, and avoiding product quality fluctuations and performance degradation caused by gelation problems.

[0286] The preferred embodiments of the present invention have been described in detail above; however, the present invention is not limited thereto. Within the scope of the inventive concept, various simple modifications can be made to the technical solutions of the present invention, including combinations of various technical features in any other suitable manner. These simple modifications and combinations should also be considered as the content disclosed in the present invention and are all within the protection scope of the present invention.

Claims

1. A methyl methacrylate polymer, characterized in that, The polymer includes structural unit A and optionally structural unit B; Wherein, the structural unit A has the structure shown in Equation I, Wherein, the structural unit B has the structure shown in Formula II and / or Formula III, Wherein, R1 is selected from C2-C4 straight-chain or branched alkyl groups, and R2 is selected from H or C1-C3 straight-chain or branched alkyl groups; Wherein, the isotacticity (mm) of the polymer is 4.1-10%, preferably 4.1-9.5%, more preferably 4.2-8.5%; and the syndiotacticity (rr) is 45-60%, preferably 50-59%, more preferably 52-59%; and The polymer has a melt index of 2-10 g / 10 min at 230 °C and 3.8 kg, preferably 3-10 g / 10 min, and more preferably 4-10 g / 10 min.

2. The polymer according to claim 1, wherein, The isotacticity of the polymer is 4.5-8.0%; And / or, the syndiotacticity of the polymer is 52.0-58.5%; And / or, the polymer has a melt index of 5-9 g / 10 min at 230°C and 3.8 kg; And / or, based on the total weight of the polymer, the content of structural unit A is 70-100% by weight, preferably 80-100% by weight, more preferably 90-100% by weight, and the content of structural unit B is 0-30% by weight, preferably 0-20% by weight, more preferably 0-10% by weight.

3. The polymer according to claim 1 or 2, wherein, The glass transition temperature of the polymer is 100-130℃, preferably 105-125℃; And / or, the polymer has a weight-average molecular weight of 7.5 × 10⁻⁶. 4 -15×10 4 g / mol; And / or, the molecular weight distribution of the polymer is 1.80-2.40, preferably 1.80-2.30, more preferably 1.80-2.25; And / or, the content of residual monomers in the polymer is less than or equal to 0.40% by weight, preferably less than or equal to 0.35% by weight; And / or, according to ISO 13468-2:2021, the transmittance of the polymer is greater than or equal to 92.0%, preferably greater than or equal to 92.5%; And / or, as determined according to ISO 14782:2021, the haze of the polymer is less than or equal to 0.35%, preferably less than or equal to 0.30%.

4. A method for preparing a methyl methacrylate polymer, characterized in that, Includes the following steps: (1) In the presence of a protective gas, methyl methacrylate, optionally comonomer X, chain transfer agent and initiator I are subjected to a prepolymerization reaction in reactor I to obtain a prepolymer solution containing the prepolymer; and (2) In the presence of a protective gas, the prepolymer solution containing the prepolymer is subjected to a final polymerization reaction in reactor II to obtain the methyl methacrylate polymer; Step (2) is carried out in the presence of initiator II; Wherein, the initiator II is different from the initiator I, and the initiator II is one or more of the compounds shown in Formula IV. R3-R8 are each independently selected from hydrogen, C1-C10 alkyl, C3-C10 cycloalkyl, C6-C15 aryl, C7-C15 arylalkyl and C7-C15 alkylaryl; or one or more pairs of R3 / R4, R5 / R6 and R7 / R8 can form an alicyclic ring of 3-15 atoms together with the carbon atoms attached to them; Preferably, R3-R8 are each independently selected from hydrogen and C1-C6 alkyl; or each pair of R3 / R4, R5 / R6, and R7 / R8 forms a five-membered, six-membered, or seven-membered alicyclic ring together with the carbon atom to which they are attached.

5. The preparation method according to claim 4, wherein, Based on the total weight of methyl methacrylate and comonomer X, the amount of methyl methacrylate is 70-100% by weight, preferably 80-100% by weight, more preferably 90-100% by weight, and the amount of comonomer X is 0-30% by weight, preferably 0-20% by weight, more preferably 0-10% by weight. And / or, based on the total weight of methyl methacrylate and comonomer X, the amount of the chain transfer agent is 0.01-1.0% by weight, preferably 0.1-0.8% by weight, more preferably 0.1-0.3% by weight; And / or, based on the total weight of methyl methacrylate and comonomer X, the amount of initiator I is 0.01-1.5% by weight, preferably 0.1-1% by weight, more preferably 0.2-0.6% by weight; And / or, based on the total weight of methyl methacrylate and comonomer X, the amount of initiator II is 0.05-2.0 wt%, preferably 0.1-1.5 wt%, more preferably 0.1-0.5 wt%.

6. The preparation method according to claim 4 or 5, wherein, In step (1), the comonomer X is selected from the structure shown in Formula 1 and / or Formula 2. Wherein, R1 is selected from C2-C4 straight-chain or branched alkyl groups, and R2 is selected from H or C1-C3 straight-chain or branched alkyl groups; And / or, wherein the chain transfer agent is selected from alkyl mercaptans, preferably from at least one of n-dodecyl mercaptan, tert-dodecyl mercaptan, n-butanethiol, n-octyl mercaptan, and tert-butanethiol; And / or, wherein the initiator I is selected from free radical initiators, preferably from peroxide initiators and azo initiators, and more preferably from at least one of azobisisobutyronitrile, azobisisoheptanenitrile, dimethyl azobisisobutyrate, benzoyl peroxide, lauroyl peroxide, tert-butyl peroxide, diisopropyl percarbonate, cumene hydroperoxide, diisopropylbenzene peroxide, and cyclohexanone peroxide.

7. The preparation method according to any one of claims 4-6, wherein, The reactor I mentioned in step (1) is a horizontal or vertical reactor I, preferably a horizontal or vertical self-cleaning reactor I; And / or, the method further includes cooling the methyl methacrylate, optionally the comonomer X, the chain transfer agent and the initiator prior to step (1); preferably, the cooling temperature is 0-20°C; And / or, the rate at which methyl methacrylate is introduced into reactor I is 0.1-1 L / min, and the rate at which comonomer X is introduced into reactor I is 0-1 L / min; And / or, the prepolymerization reaction in step (1) is carried out under stirring conditions; preferably, the stirring rate of the prepolymerization reaction in step (1) is 2-100 rpm; And / or, the reaction temperature of the prepolymerization reaction in step (1) is 80-130°C, preferably 85-125°C; And / or, the reaction time of the prepolymerization reaction in step (1) is 10-90 minutes, preferably 10-60 minutes; And / or, the temperature fluctuation of the prepolymerization reaction in step (1) is less than 3°C; And / or, the yield of the prepolymer in the prepolymerization reaction described in step (1) is 20-40% by weight.

8. The preparation method according to any one of claims 4-7, wherein, The reactor II mentioned in step (2) is a horizontal reactor II, preferably a horizontal self-cleaning reactor II; And / or, the rate at which the prepolymer-containing prepolymer solution is introduced into reactor II is 0.1-1 L / min; And / or, the final polymerization reaction in step (2) is carried out under stirring conditions; preferably, the stirring rate of the final polymerization reaction in step (2) is 2-30 rpm, more preferably 5-20 rpm; And / or, the reaction temperature of the final polymerization reaction in step (2) is 130-190°C, preferably 135-185°C; And / or, the reaction time of the final polymerization reaction in step (2) is 10-90 minutes, preferably 15-60 minutes; And / or, the temperature fluctuation of the final polymerization reaction in step (2) is less than 3°C; And / or, the temperature of the final polymerization reaction in step (2) is higher than the temperature of the prepolymerization reaction, preferably the temperature of the final polymerization reaction is 20-90°C higher than the temperature of the prepolymerization reaction; And / or, after the final polymerization reaction is completed, the yield of the final polymer is equal to or greater than 80% by weight, preferably equal to or greater than 85% by weight.

9. The preparation method according to any one of claims 4-8, wherein Steps (1) and (2) are both carried out in the presence of initiator II; And / or, the reaction temperature of the prepolymerization reaction in step (1) is 80-130°C, preferably 85-125°C, and the temperature of the final polymerization reaction is higher than the temperature of the prepolymerization reaction, preferably 20-90°C higher than the temperature of the prepolymerization reaction, and more preferably 20°C to 80°C higher than the temperature of the prepolymerization reaction.

10. The preparation method according to any one of claims 4-9, wherein, The method further includes discharging, devolatilizing and extruding the methyl methacrylate polymer after the final polymerization reaction; Preferably, the discharge temperature is 165-200℃, more preferably 170-190℃. Preferably, the discharge rate is 5-25 rpm, more preferably 8-20 rpm; Preferably, the devolatilization temperature is 185-245℃, more preferably 190-230℃, and the devolatilization pressure is less than or equal to 100Pa, more preferably less than or equal to 25Pa; Preferably, the devolatilization rate is 80-200 rpm, more preferably 80-180 rpm.

11. The preparation method according to any one of claims 4-10, wherein, The initiator II is selected from one or more of the following:

12. The preparation method according to any one of claims 4-11, wherein, The prepared methyl methacrylate polymer is the methyl methacrylate polymer according to any one of claims 1-3.

13. The methyl methacrylate polymer prepared by the preparation method according to any one of claims 4-12.

14. The use of a methyl methacrylate polymer according to any one of claims 1-3 and 13 in at least one of liquid crystal displays, optical materials, automotive headlights, and electronic products.

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