Low-haze PMMA optical plate and preparation method and application thereof

Abstract

This invention belongs to the technical field of PMMA optical sheet technology, specifically relating to a low-haze PMMA optical sheet, its preparation method, and applications. It comprises the following components: 0.10–0.50 parts of flow conditioner; 0.05–0.30 parts of lubricant; 0.03–0.15 parts of primary antioxidant; 0.03–0.15 parts of secondary antioxidant; 0–0.30 parts of optical stabilizer; and optical-grade PMMA resin as the balance. The flow conditioner, lubricant, primary antioxidant, secondary antioxidant, and optical stabilizer all exhibit good compatibility with PMMA. The PMMA optical sheet has a total light transmittance ≥92.0% and a haze ≤0.60%. Compared with existing technologies, the low-haze PMMA optical sheet prepared by this invention has high light transmittance, low haze, and good dimensional stability, and can be widely used in light guide plates, display protection plates, lighting panels, high-transparency observation windows, transparent protective structural components, and advertising display boards.

Description

Technical Field

[0001] This invention belongs to the field of PMMA optical sheet technology, specifically relating to a low-haze PMMA optical sheet, its preparation method, and its application. Background Technology

[0002] Polymethyl methacrylate (PMMA) is widely used in display panels, light guide plates, lampshades, optical protective plates, advertising display boards, and precision transparent components due to its high light transmittance, excellent weather resistance, low density, and good processing performance. Especially in optical sheet applications, the material not only needs high total light transmittance but also low haze to ensure image clarity, perspective effect, and optical uniformity. Haze reflects the degree to which light passing through the material deviates from the incident direction; the lower the haze, the higher the directionality of the light after transmission, and the better the visual clarity of the material.

[0003] However, in the existing PMMA optical sheet fabrication process, factors such as the internal micro-uniform structure of the material, impurities, bubbles, poorly dispersed particles, surface micro-defects, and internal stress generated during molding can all cause incident light scattering, thereby increasing the haze of the sheet and affecting its optical quality and end-application performance. This haze problem is particularly pronounced in scenarios with large sheet thickness or high transparency requirements.

[0004] Existing low-haze PMMA sheets are typically prepared using the following methods: (1) High-purity PMMA resin is selected for direct extrusion or casting molding; (2) Improve processing fluidity by adding a small amount of lubricant, flow modifier and other additives to reduce melt fracture and surface defects; (3) Reduce surface ripples and forming defects of the sheet by optimizing extrusion temperature, die structure and cooling method; (4) The internal stress is reduced by subsequent annealing treatment, which improves transparency and appearance.

[0005] Existing processes still have significant shortcomings: they often focus more on the molding performance and appearance integrity of the sheet material, while neglecting the control of microscopic factors that cause light scattering. First, residual volatiles, moisture, gel particles, impurities, or microbubbles formed during processing in the raw materials can all become scattering centers, leading to increased haze in the sheet material. Second, some additives have limited compatibility with the PMMA matrix; insufficient dispersion or refractive index mismatch can also increase interfacial scattering, hindering the production of low-haze sheets. Third, during melt extrusion, uneven melt plasticization, excessively high local temperatures, or excessive shear can easily cause localized degradation of molecular chains, melt flow marks, or residual stress, thus affecting the optical uniformity of the sheet material. Furthermore, the insufficient precision in controlling devolatilization, filtration, melt pressure stabilization, and cooling in existing processes can also result in fine ripples, internal stress zones, or microscopic refractive index fluctuations in the final product, leading to increased haze. Summary of the Invention

[0006] To address the problems existing in the prior art, this invention provides a low-haze PMMA optical substrate, its preparation method, and its application.

[0007] The technical solution adopted in this invention is as follows: A low-haze PMMA optical sheet, with a total component weight of 100 parts, includes the following components: Flow conditioner 0.10–0.50 parts; Lubricant 0.05–0.30 parts; 0.03–0.15 parts of the main antioxidant; 0.03–0.15 parts of auxiliary antioxidant; Optical stabilizer 0-0.30 parts; The margin is optical grade PMMA resin; The flow conditioner, lubricant, primary antioxidant, secondary antioxidant, and optical stabilizer all have good compatibility with PMMA; PMMA optical sheets have a total light transmittance of ≥92.0% and a haze of ≤0.60%.

[0008] Preferably, the optical grade PMMA resin is a low-impurity, low-gel particle PMMA resin with a total light transmittance ≥92.0%, haze ≤0.60%, volatile matter ≤0.30%, and moisture ≤0.05%.

[0009] Preferably, the lubricant is pentaerythritol tetrastearate, polyethylene wax, or an amide lubricant.

[0010] Preferably, the primary antioxidant is antioxidant 1010 with a purity ≥ 98%; the secondary antioxidant is antioxidant 168 with a purity ≥ 98%.

[0011] The method for preparing low-haze PMMA optical substrate in this application includes the following steps: S1. Raw material drying: Optical grade PMMA resin, flow conditioner, lubricant, main antioxidant, auxiliary antioxidant and optical stabilizer are dried and pretreated respectively. S2. Raw material metering and premixing: Weigh out optical grade PMMA resin, flow conditioner, lubricant, main antioxidant, auxiliary antioxidant and optical stabilizer according to the formula ratio, and premix at low or medium speed. S3. Melting, plasticizing and homogenizing: The premixed material is added to the extrusion equipment for melting, plasticizing and homogenizing. S4. Melt filtration: The melt passes through a metal screen or melt filter to remove unmelted particles, microgels and foreign impurities. S5. Vacuum devouring: A vacuum devouring zone is set in the melt conveying section, with a vacuum degree of -0.06 to -0.095 MPa, to remove residual moisture, low molecular weight volatiles and entrained gases. S6. Pressure stabilization and die forming: The devolatilized melt is pressure stabilizing and conveyed to the sheet die by the melt pump. The die temperature is 220-240℃. The melt is extruded through a uniform flow channel to form a plate-shaped melt. S7. Calendering and temperature control cooling: The plate-shaped melt enters the three-roll calendering system for thickness determination and surface smoothing. The temperature of the calendering roller is 70-110℃, and a gradient cooling method is used to reduce residual stress and surface micro-ripples. S8. Annealing treatment: The molded sheet is annealed at 70-95℃ for 2-6 hours and then slowly cooled to room temperature to further release internal stress and improve optical uniformity and dimensional stability.

[0012] Preferably, in step S1, the optical grade PMMA resin is dried at 80–90°C for 3–6 hours.

[0013] Preferably, in step S3, the extrusion temperature is 190–240°C and the screw speed is 20–120 rpm.

[0014] Preferably, in step S4, the filtration accuracy is controlled between 80 and 300 mesh.

[0015] The applications of the low-haze PMMA optical sheet described in this application include, but are not limited to, light guide plates, display protection plates, lighting panels, high-transparency viewing windows, transparent protective structural components, and advertising display boards.

[0016] This invention uses high-purity optical-grade PMMA resin as the main material of the sheet material. The selected PMMA resin is optical-grade or low-impurity PMMA resin. Each additive is selected from those with good compatibility with PMMA, and the addition amount is controlled within a low range, which can effectively avoid enhanced light scattering caused by phase separation, additive precipitation, or refractive index differences. Through thorough drying, clean premixing, melt homogenization, melt filtration, and vacuum devolatilization of raw materials, microbubbles, impurities, and gel particles inside the sheet material are reduced. Through precision die extrusion, calendering, and controlled cooling, surface defects and thickness fluctuations are reduced. Annealing treatment reduces residual stress in the sheet material and improves optical uniformity. Ultimately, the goal of significantly reducing haze is achieved.

[0017] Compared with existing technologies, the beneficial effects of this invention are as follows: By selecting high-purity PMMA resin, combining it with a highly compatible low-addition additive system, and systematically optimizing key process steps such as drying and dehumidification, melt plasticizing, melt filtration, vacuum devolatilization, pressure stabilization and conveying, precision die forming, temperature control and cooling, and subsequent annealing, light scattering defects inside and on the surface of the material are effectively reduced, thereby obtaining PMMA optical sheets with high light transmittance, low haze, and good dimensional stability. The low-haze PMMA optical sheets prepared by this invention have a total light transmittance ≥92.0% and haze ≤0.60%, and can be widely used in light guide plates, display protection plates, lighting panels, high-transparency observation windows, transparent protective structural components, and advertising display boards. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the structure of the low-haze PMMA optical material of the present invention. Detailed Implementation

[0019] To facilitate understanding of the present invention, it will be described in more detail below with reference to the accompanying drawings and specific embodiments. However, the present invention can be implemented in many different forms and is not limited to the embodiments described in this specification. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of the present invention.

[0020] A low-haze PMMA optical sheet, comprising 100 parts by weight of all components, includes the following components: Flow conditioner 0.10–0.50 parts; Lubricant 0.05–0.30 parts; 0.03–0.15 parts of the main antioxidant; 0.03–0.15 parts of auxiliary antioxidant; 0 to 0.30 parts of optical stabilizer; the balance is optical grade PMMA resin.

[0021] The selected PMMA resin is preferably optical grade or low-impurity PMMA resin, but no specific brand or model is limited; the additives should have good compatibility with PMMA and the amount added should be controlled within a low range to avoid enhanced light scattering caused by phase separation, additive precipitation or refractive index difference.

[0022] In one embodiment, the low-haze PMMA optical sheet, with a total light transmittance ≥92.0%, haze ≤0.60%, volatile matter ≤0.30%, and moisture ≤0.05% of low-impurity, low-gel particle PMMA resin, is used to ensure the basic transparency and low-haze performance of the sheet when the thickness is 3.0mm.

[0023] In one embodiment, the flow conditioner is one or more of the following: methacrylate processing aids, low molecular weight PMMA resin, and acrylate flow modifiers, which are compatible with PMMA resin, and is used to improve melt flow uniformity and extrusion stability.

[0024] In one embodiment, the lubricant is pentaerythritol tetrastearate; without significantly increasing haze, polyethylene wax, amide lubricants, or other transparent processing lubricants with good compatibility with PMMA may also be selected.

[0025] In one embodiment, the primary antioxidant is antioxidant 1010 with a purity ≥98%, used to inhibit the thermo-oxidative degradation of PMMA resin during melt processing, and reduce yellowing, gel particles, or decline in optical properties caused by material degradation.

[0026] In one embodiment, the auxiliary antioxidant is antioxidant 168 with a purity of ≥98%, which is used in conjunction with antioxidant 1010 to further improve the processing stability of the material during melt extrusion and reduce the risk of microgel formation or color changes during processing.

[0027] In one embodiment, the optical stabilizer is a UV absorber or light stabilizer with good compatibility with PMMA resin, having a purity ≥98%, used to improve the optical stability and weather resistance of PMMA optical sheets during long-term use, such as the triazine-based high-efficiency UV absorber TINUVIN 1577, manufactured by BASF, Germany. The amount of the optical stabilizer is controlled within the range of 0 to 0.30 parts to avoid increased haze due to excessive addition or insufficient compatibility.

[0028] Technical principle explanation: (1) The basic principle of reducing the haze of PMMA sheets in this invention is to reduce the light scattering sources inside and on the surface of the material. When light propagates in PMMA sheets, it may be scattered if it encounters microbubbles, gel particles, impurities, phase separation regions, surface micro-ripples or regions with uneven refractive index caused by internal stress, which will lead to an increase in haze.

[0029] (2) On the one hand, the present invention selects optical grade PMMA resin with low impurities and low volatility, and dries it thoroughly before processing to reduce the defects of bubbles and silver streaks caused by moisture and small molecule volatiles; on the other hand, by selecting an additive system with good compatibility with PMMA and a low addition amount, the invention avoids the adverse effects of additive enrichment, phase separation and refractive index change on haze.

[0030] (3) In terms of process, the present invention removes microgels, unmelted particles, impurities and residual gases through melt homogenization, melt filtration and vacuum devolatilization; reduces surface flow marks, thickness fluctuations and molding stress through pressure-stabilized conveying, precision die extrusion, calendering and shaping and gradient cooling; and further releases internal stress and reduces local refractive index fluctuations through annealing. The above measures work synergistically to give PMMA sheets high light transmittance, low haze and good mechanical properties.

[0031] The present invention also provides a method for preparing the above-mentioned PMMA composite material, comprising the following steps: (1) Raw material drying Optical-grade PMMA resin, flow conditioner, lubricant, primary antioxidant, secondary antioxidant, and optical stabilizer are pretreated separately. The optical-grade PMMA resin is preferably dried at 80–90°C for 3–6 hours to reduce the moisture and volatile content of the raw material, thereby minimizing the formation of bubbles, streaks, and micropores during melt processing.

[0032] (2) Raw material metering and premixing Weigh out the optical grade PMMA resin, flow conditioner, lubricant, main antioxidant, auxiliary antioxidant and optical stabilizer according to the formula ratio, and premix them at low or medium speed under clean conditions to make the components initially uniformly dispersed and to avoid the mixing of foreign dust and impurities.

[0033] (3) Melt plasticization and homogenization The premixed material is added to an extrusion apparatus for melt plasticization and homogenization. The preferred extrusion temperature is 190–240°C, and the preferred screw speed is 20–120 rpm. Through stable plasticization and moderate shearing, the additives are evenly distributed in the PMMA matrix, while avoiding localized overheating degradation or melt defects caused by excessive shearing.

[0034] (4) Melt filtration The melt is passed through an 80-300 mesh metal filter or a melt filter with equivalent filtration precision to remove unmelted particles, microgels and foreign impurities, and reduce internal scattering centers.

[0035] (5) Vacuum devouring A vacuum devolatilization zone is set up in the melt conveying section, with a vacuum degree preferably between -0.06 and -0.095 MPa, to remove residual moisture, low-molecular-weight volatiles, and entrained gases.

[0036] (6) Pressure stabilization and conveying and die forming The devolatilized melt is pumped under stable pressure to the sheet die head, with the die head temperature preferably being 220-240°C. The melt is then extruded through a uniform flow channel to form a plate-shaped melt.

[0037] (7) Calendering and temperature control cooling The plate-shaped melt enters the three-roll calendering system for thickness determination and surface smoothing. The calendering roller temperature is preferably 70-110℃, and a gradient cooling method is used to reduce residual stress and surface micro-ripples.

[0038] (8) Annealing treatment The molded sheet is annealed at 70–95°C for 2–6 hours and then slowly cooled to room temperature to further release internal stress and improve optical uniformity and dimensional stability.

[0039] (9) Cutting and inspection The annealed sheet material is cut and tested for total light transmittance, haze, thickness uniformity, tensile properties, bending properties, impact properties, surface defects, and appearance quality.

[0040] Example 1: A low-haze PMMA optical sheet, the structure of which is as follows Figure 1 As shown, by weight, PMMA resin comprises 99.30 parts, flow conditioner 0.30 parts, PETS lubricant 0.15 parts, antioxidant 1010 0.08 parts, antioxidant 168 0.07 parts, and optical stabilizer 0.10 parts; the lubricant is pentaerythritol tetrastearate, and the optical stabilizer is TINUVIN1577.

[0041] The preparation method is as follows: S1. Raw material drying: PMMA resin, flow conditioner, PETS lubricant, antioxidant 1010, antioxidant 168, and optical stabilizer are pretreated separately. Optical grade PMMA resin is preferably dried at 80–90°C for 3–6 hours to reduce the moisture and volatile content in the raw material, thereby minimizing the formation of bubbles, streaks, and micropores during melt processing.

[0042] S2. Raw material metering and premixing: Weigh PMMA resin, flow conditioner, PETS lubricant, antioxidant 1010, antioxidant 168 and optical stabilizer according to the formula ratio. Premix at low or medium speed under clean conditions, with a rotation speed of 200-600 rpm, so that the components are initially evenly dispersed and foreign dust and impurities are avoided from mixing in.

[0043] S3. Melt Plasticization and Homogenization: The premixed material is added to the extrusion equipment for melt plasticization and homogenization. The extrusion temperature is preferably 190–240℃, and the screw speed is preferably 20–120 rpm. Through stable plasticization and moderate shearing, the additives are evenly distributed in the PMMA matrix, while avoiding local overheating degradation or melt defects caused by excessive shearing.

[0044] S4. Melt filtration: The melt passes through an 80-300 mesh metal filter or a melt filter with equivalent filtration precision to remove unmelted particles, microgels, and foreign impurities, and reduce internal scattering centers.

[0045] S5. Vacuum devolatilization: A vacuum devolatilization zone is set in the melt conveying section, with a vacuum degree preferably of -0.06 to -0.095 MPa, to remove residual moisture, low molecular weight volatiles and entrained gases.

[0046] S6. Pressure stabilization and die forming: The melt after devolatilization is pressure stabilized and conveyed to the sheet die by the melt pump. The die temperature is preferably 220-240℃. The melt is extruded through a uniform flow channel to form a plate-shaped melt.

[0047] S7. Calendering and Temperature Control: The sheet-like melt enters the three-roll calendering system for thickness determination and surface smoothing. The upper roll temperature is set to 100~110℃, the middle roll temperature to 90~100℃, and the lower roll temperature to 70~90℃. The roll speed is controlled at 0.8~2.5m / min, matching the die extrusion speed. The roll gap is set with reference to the sheet thickness, generally 0.05~0.1mm smaller than the sheet thickness. The inter-roll pressure is 0.3~0.6MPa. The wrap angle between the melt and the middle roll is 120°~150°.

[0048] S8. Annealing treatment: The molded sheet is annealed at 80℃ for 4 hours and then slowly cooled to room temperature to further release internal stress and improve optical uniformity and dimensional stability. Finally, a PMMA optical sheet with a uniform internal structure and smooth upper and lower surfaces is obtained, with a total light transmittance of 92.6%, a haze of 0.45%, and low scattering. It can be widely used in light guide plates, display protection plates, lighting panels, high-transparency observation windows, transparent protective structural components, and advertising display boards.

[0049] Example 2: A low-haze PMMA optical sheet, comprising, by weight, 99.10 parts optical-grade PMMA resin, 0.40 parts flow conditioner, 0.20 parts PETS lubricant, 0.10 parts antioxidant 1010, 0.10 parts antioxidant 168, and 0.10 parts optical stabilizer; the preparation method is the same as in Example 1, except that step S8 annealing is performed at 85°C for 4 hours.

[0050] Example 3: A low-haze PMMA optical sheet, comprising, by weight, 99.55 parts optical-grade PMMA resin, 0.20 parts flow conditioner, 0.10 parts PETS lubricant, 0.05 parts antioxidant 1010, 0.05 parts antioxidant 168, and 0.05 parts optical stabilizer; the preparation method is the same as in Example 1, except that step S8 annealing is performed at 80°C for 3 hours.

[0051] The PMMA plates prepared in Examples 1-3 have the following appearance: smooth surface, no obvious impurities, no obvious bubbles or flow marks, and good optical uniformity.

[0052] Comparative Example 1: A low-haze PMMA optical sheet, comprising 100 parts by weight of optical-grade PMMA resin; using a conventional extrusion process, with an extrusion temperature of 190–240°C and a screw speed of 20–120 rpm, without melt filtration, vacuum devolatilization, or annealing. The PMMA sheet prepared in Comparative Example 1 exhibits the following appearance: locally visible microbubbles or crystal points.

[0053] Comparative Example 2: A low-haze PMMA optical sheet, with the same composition as Example 1; the preparation method did not involve vacuum devolatilization and annealing, but was otherwise the same as Example 1. Appearance of the PMMA sheet prepared in Comparative Example 2: slight flow marks and internal stress lines were observed in some areas.

[0054] Comparative Example 3: A low-haze PMMA optical sheet, comprising 98.70 parts by weight of optical-grade PMMA resin, 0.80 parts by weight of flow conditioner, and 0.50 parts by weight of PETS lubricant; the preparation method was the same as that of Comparative Example 1. The PMMA sheet prepared in Comparative Example 3 exhibited uneven dispersion of additives and a significantly increased haze.

[0055] From the appearance of the sheet material, compared with Comparative Examples 1-3, Examples 1-3 have better surface, visual clarity and optical quality.

[0056] The components of Examples 1-3 and Comparative Examples 1-3 are summarized in Table 1.

[0057] Table 1 Summary of components in Examples 1-3 and Comparative Examples 1-3 Examples 1-3 and Comparative Examples 1-3 were tested, and the performance data are shown in Table 2. Test items: Optical performance was tested according to GB / T2410 or equivalent standards for total transmittance and haze; tensile performance was tested according to GB / T1040 or equivalent standards; bending performance was tested according to GB / T9341 or equivalent standards; impact performance was tested according to GB / T1043 or equivalent standards. The thickness of the test samples was 3.0 mm.

[0058] Table 2 Performance Data Statistics of Examples 1-3 and Comparative Examples 1-3 Table 2 shows that the haze of PMMA sheets prepared with a thickness of 3 mm in Examples 1-3 was 0.45-0.52%, significantly lower than that of Comparative Examples 1-3; moreover, the total light transmittance was higher than that of Comparative Examples 1-3, while the tensile and other mechanical properties were at the same level. The conclusion is that compared with existing ordinary PMMA sheet preparation processes, this invention can significantly reduce haze while maintaining a high level of total light transmittance, and also takes into account basic mechanical properties and appearance quality, making it suitable for preparing high-quality PMMA optical sheets.

[0059] Analysis based on specific processes: (1) This invention uses high-purity optical-grade PMMA resin and dries it thoroughly before processing, which can reduce microbubbles and silver streaks formed by moisture and volatiles during melt processing, thereby reducing bulk scattering. (2) This invention uses a low-addition additive system with good compatibility with PMMA, which can improve processing stability while avoiding additive enrichment, phase separation and interface scattering, ensuring high light transmittance and low haze of the board. (3) This invention sets up melt filtration and vacuum devolatilization steps, which can remove microgels, unmelted particles, foreign impurities and residual gases, reducing scattering centers that affect the optical quality of the board from the source. (4) This invention uses stable pressure conveying, precision die forming, calendering and cooling and subsequent annealing to synergistically control the surface flatness, thickness uniformity and internal stress of the board, which can reduce surface scattering and internal refractive index fluctuations, and obtain lower haze and higher transparency.

[0060] The core improvement of this invention compared to existing technologies lies in the synergistic optimization of key process steps, including high-purity PMMA resin, a low-addition, highly compatible additive system, and processes such as drying and dehumidification, melt plasticizing, melt filtration, vacuum devolatilization, pressure stabilization and conveying, precision die forming, temperature control and cooling, and annealing. This overall reduction of light scattering sources within and on the surface of the material, rather than relying solely on adjustments to the material formulation, achieves a significant reduction in haze while maintaining high total transmittance. Total transmittance and haze are different indicators: total transmittance reflects the total amount of light transmitted through the material, while haze reflects the degree of scattering of transmitted light. Therefore, the focus of this invention is not simply to increase transmittance, but to reduce scattering caused by factors such as bubbles, gel particles, surface micro-defects, and internal stress. The low-haze PMMA optical sheet prepared by this invention can be widely used in light guide plates, display protection plates, lighting panels, high-transparency observation windows, transparent protective structural components, and advertising display panels.

[0061] To further improve the implementation of this invention, while meeting basic requirements such as optics and mechanics, the single-screw extruder can be replaced with a low-shear twin-screw extruder or other continuous plasticizing equipment suitable for optical-grade sheet production. The melt filtration precision and filter combination can also be adjusted according to the sheet thickness and optical grade requirements. Without significantly increasing light scattering, other heat stabilizers, UV absorbers, light stabilizers, or surface abrasion-resistant modifiers with good compatibility with PMMA can be selected. For products with higher optical requirements, online defect detection, clean production environment control, and automatic thickness feedback control steps can be added. Although the above alternative solutions differ in equipment type, additive type, or process details, their core remains the same: achieving low haze by reducing light scattering sources inside and on the surface of the sheet. Therefore, they are all alternative implementations of the inventive concept.

[0062] Note: Unless otherwise specified, materials are available commercially.

[0063] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

Claims

1. A low-haze PMMA optical substrate, characterized in that, The total amount of components, based on parts by mass, is 100 parts, and includes the following components: Flow conditioner 0.10–0.50 parts; Lubricant 0.05–0.30 parts; 0.03–0.15 parts of the main antioxidant; 0.03–0.15 parts of auxiliary antioxidant; Optical stabilizer 0-0.30 parts; The margin is optical grade PMMA resin; The flow conditioner, lubricant, primary antioxidant, secondary antioxidant, and optical stabilizer all have good compatibility with PMMA; PMMA optical sheets have a total light transmittance of ≥92.0% and a haze of ≤0.60%.

2. The low-haze PMMA optical substrate according to claim 1, characterized in that, The optical-grade PMMA resin is a low-impurity, low-gel-particle PMMA resin with a total light transmittance ≥92.0%, haze ≤0.60%, volatile matter ≤0.30%, and moisture ≤0.05%.

3. The low-haze PMMA optical substrate according to claim 1, characterized in that, The lubricant is pentaerythritol tetrastearate, polyethylene wax, or an amide lubricant.

4. The low-haze PMMA optical substrate according to claim 1, characterized in that, The primary antioxidant is antioxidant 1010 with a purity ≥98%; the secondary antioxidant is antioxidant 168 with a purity ≥98%.

5. The method for preparing low-haze PMMA optical substrate as described in claim 1, characterized in that, Includes the following steps: S1. Raw material drying: Optical grade PMMA resin, flow conditioner, lubricant, main antioxidant, auxiliary antioxidant and optical stabilizer are dried and pretreated respectively. S2. Raw material metering and premixing: Weigh out optical grade PMMA resin, flow conditioner, lubricant, main antioxidant, auxiliary antioxidant and optical stabilizer according to the formula ratio, and premix at low or medium speed. S3. Melting, plasticizing and homogenizing: The premixed material is added to the extrusion equipment for melting, plasticizing and homogenizing. S4. Melt filtration: The melt passes through a metal screen or melt filter to remove unmelted particles, microgels and foreign impurities. S5. Vacuum devouring: A vacuum devouring zone is set in the melt conveying section, with a vacuum degree of -0.06 to -0.095 MPa, to remove residual moisture, low molecular weight volatiles and entrained gases. S6. Pressure stabilization and die forming: The devolatilized melt is pressure stabilizing and conveyed to the sheet die by the melt pump. The die temperature is 220-240℃. The melt is extruded through a uniform flow channel to form a plate-shaped melt. S7. Calendering and temperature control cooling: The plate-shaped melt enters the three-roll calendering system for thickness determination and surface smoothing. The temperature of the calendering roller is 70-110℃, and a gradient cooling method is used to reduce residual stress and surface micro-ripples. S8. Annealing treatment: The molded sheet is annealed at 70-95℃ for 2-6 hours and then slowly cooled to room temperature to further release internal stress and improve optical uniformity and dimensional stability.

6. The preparation method according to claim 5, characterized in that, In step S1, the optical grade PMMA resin is dried at 80–90°C for 3–6 hours.

7. The preparation method according to claim 5, characterized in that, In step S3, the extrusion temperature is 190–240°C and the screw speed is 20–120 rpm.

8. The preparation method according to claim 5, characterized in that, In step S4, the filtration accuracy is controlled between 80 and 300 mesh.

9. The application of the low-haze PMMA optical sheet as described in claim 1, characterized in that, Applications include, but are not limited to, light guide plates, display protection plates, lighting panels, high-transparency viewing windows, transparent protective structural components, and advertising display boards.

Images