Multilayer PMMA (polymethyl methacrylate) optical base film, preparation method of multilayer PMMA optical base film and polarizing plate comprising multilayer PMMA optical base film

Abstract

The multi-layer PMMA optical base film comprises a first PMMA base layer, a second PMMA base layer arranged on the surface of the first PMMA base layer, and a third PMMA base layer arranged on the surface, away from the first PMMA base layer, of the second PMMA base layer; toughening particles with a first particle size are arranged in the first PMMA base layer and the third PMMA base layer, toughening particles with a second particle size are arranged in the second base layer, and the first particle size is larger than the second particle size; each toughening particle comprises a shell formed by copolymerization of styrene and methyl methacrylate and an inner core formed by butyl acrylate, and the toughening particles are subjected to surface treatment. The PMMA optical base film is designed to be of a three-layer structure, different layers comprise toughening particles with different particle sizes and subjected to surface treatment, the particles with different particle sizes can absorb and disperse external force, the stress concentration phenomenon is eliminated, the toughness of the PMMA optical base film is remarkably improved, and the undesirable phenomena such as film sliding and bracing wires are reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of optical thin films, and particularly relates to a multi-layer PMMA optical base film, a preparation method thereof, and a polarizing plate containing the same. Background Art

[0002] Liquid crystal display devices are widely used, from televisions, laptop computers to liquid crystal monitors, projectors, in-vehicle navigation systems, mobile phones, etc. The polarizing plates of liquid crystal display devices contain various optical films, such as polarizer protective films, diffusion films, brightness enhancement films, etc. These films are mainly prepared by surface treatment, coating or processing on the surface of an optical base film as the substrate.

[0003] PMMA has excellent light transmittance, low water absorption rate, and good chemical stability, and is one of the more ideal optical base film materials. However, it has relatively large brittleness and is prone to film breakage during the production process. The existing patent CN117445507B discloses a heat-resistant and toughened PMMA film and a preparation method thereof, which improve the toughness of the PMMA film by adding a toughening agent. However, the direct addition of this toughening agent easily causes problems such as rib tension lines and film slipping phenomena in the PMMA film after preparation and molding.

[0004] Therefore, it is an urgent problem to design a PMMA film with good toughness, which is not prone to film slipping phenomena and rib tension lines. Summary of the Invention

[0005] To achieve the above object, the present application provides a multi-layer PMMA optical base film with good toughness, which is not prone to film slipping phenomena and rib tension lines.

[0006] In a first aspect, the present application provides a multi-layer PMMA optical base film, including a first PMMA base layer, a second PMMA base layer disposed on the surface of the first PMMA base layer, and a third PMMA base layer disposed on the surface of the second PMMA base layer away from the first PMMA base layer; toughening particles with a first particle size are disposed in the first PMMA base layer and the third PMMA base layer, toughening particles with a second particle size are disposed in the second base layer, and the first particle size is greater than the second particle size; the shell material of the toughening particles is a copolymer of styrene and methyl methacrylate, and the core material of the toughening particles contains butyl acrylate.

[0007] More specifically, the toughening particles are surface-treated. The surface treatment is specifically as follows: The toughening particles are placed under plasma treatment at a voltage of 8.1 - 8.8 kV and a frequency of 11 - 13 KHz for 5 - 7 min, then placed in deionized water and ultrasonically dispersed for 5 - 10 min. After adding methacryloxypropylcage polyhedral oligomeric silsesquioxane, ultrasonically disperse for another 20 - 30 min. After the ultrasonic treatment is completed, filter and dry to obtain the surface-treated toughening particles.

[0008] More specifically, the first particle size is 200 - 280 nm.

[0009] More specifically, the second particle size is 100 - 180 nm.

[0010] More specifically, the thickness of the first PMMA base layer is equal to the thickness of the third PMMA base layer.

[0011] In a second aspect, the present application provides a method for preparing the above multi-layer PMMA optical base film, including the following steps:

[0012] S1. Prepare the second PMMA base layer particles. Mix 95 - 105 parts by weight of polymethyl methacrylate resin pellets and 0.1 - 0.5 parts of second particle size toughening particles, and dry under reduced pressure at 105 - 110 °C for 6 - 8 h. Then add 0.1 - 1 part of lubricant and extrude and pelletize at 220 - 230 °C to obtain the second PMMA base layer particles;

[0013] S2. Prepare the first PMMA base layer particles or the third PMMA base layer particles. Mix 95 - 105 parts by weight of polymethyl methacrylate resin pellets and 0.1 - 0.5 parts of first particle size toughening particles, and dry under reduced pressure at 105 - 110 °C for 6 - 8 h. Then add 0.1 - 1 part of lubricant and extrude and pelletize at 240 - 245 °C to obtain the first PMMA base layer particles or the third PMMA base layer particles;

[0014] S3. Vacuum-dry the first PMMA base layer particles, the second PMMA base layer particles and the third PMMA base layer particles at 110 - 120 °C for 8 - 10 h. After drying, supply them to an extruder for three-layer co-extrusion into a sheet, cool at 15 - 20 °C, calender, and then longitudinally stretch by 1.9 - 2.0 times and transversely stretch by 2.1 - 2.2 times to make the above multi-layer PMMA optical base film.

[0015] More specifically, the lubricant is a polyester-modified silicone lubricant.

[0016] In a third aspect, the present application provides a polarizing plate, including the above multi-layer PMMA optical base film. The multi-layer PMMA optical base film can be used as the upper protective film or the lower protective film of the PVA polarizer.

[0017] More specifically, the polarizing plate sequentially includes a functional layer, an upper PVA protective film, a PVA polarizer, a lower PVA protective film, a pressure-sensitive adhesive layer, and a release film from top to bottom. Both the upper PVA protective film and the lower PVA protective film are the multi-layer PMMA optical base films.

[0018] The beneficial effects of the present invention are as follows: The PMMA of the present invention is designed with a three-layer structure, wherein the upper surface layer and the lower surface layer contain toughening particles with larger particle sizes after surface treatment, and the middle layer contains toughening particles with smaller particle sizes after surface treatment. Among them, the toughening particles with larger particle sizes after surface treatment can increase the roughness of the film surface layer, improve the friction between the film and other materials, and thus prevent the occurrence of the film slipping phenomenon. At the same time, the toughness can be enhanced. The large-particle-size toughening particles, as "stress concentration points", can absorb and disperse energy when the film is subjected to external forces, prevent the propagation of cracks, and improve the toughness of the film. The toughening particles with smaller particle sizes after surface treatment can, on the one hand, be more evenly distributed in the middle layer of the film, playing a role in filling and bridging, and helping to eliminate the rib tension lines caused by material non-uniformity or stress concentration. On the other hand, they can increase the density and uniformity of the film, thereby improving the overall strength of the film. Therefore, by adding toughening particles with larger particle sizes after surface treatment to the upper and lower surface layers of the film and adding toughening particles with smaller particle sizes after surface treatment to the middle layer, the toughness of the film can be significantly improved, and defects such as film slipping and rib tension lines can be reduced.

[0019] The toughening particles are selected as core-shell structure particles with butyl acrylate as the core and a copolymer of styrene and methyl methacrylate as the shell. When the material is subjected to external forces, the core-shell structure particles can serve as stress concentration points, causing the surrounding matrix resin to undergo yield and plastic deformation. At the same time, the rigidity of the shell layer can limit the excessive deformation of the core layer and prevent the material from brittle fracture. This mechanism of stress concentration and dispersion helps to improve the toughness of the material.

[0020] The toughening particles are treated by plasma before use. Plasma treatment can form tiny uneven structures on the particle surface, increase its roughness, and reduce particle agglomeration. It will also introduce positive and negative charges on the particle surface, and the interaction between these charges can further promote the uniform dispersion of the particles in the PMMA matrix. In addition, after the particles are modified by plasma, a large number of active groups (such as hydroxyl groups, carboxyl groups, etc.) are generated on the surface. The added methacryloxypropylcage polyhedral oligomeric silsesquioxane will interact with the active groups on the particle surface. At the same time, the double bonds in the methacryloxypropyl groups will copolymerize and crosslink with the polymer matrix, improving the dispersibility and stability of the particles in the polymer substrate, enhancing the uniformity and smoothness of the film, reducing the internal stress concentration, and thus reducing adverse problems such as rib lines. And it further enhances the toughness of the film, prevents film breakage. The contained cage-like inorganic framework structure also further improves the heat resistance and stability of the PMMA film material. Description of the Drawings

[0021] Figure 1 It is a schematic diagram of the structure of the multi-layer PMMA optical base film in this application.

[0022] In the figure: 1. The first PMMA base layer; 2. The second PMMA base layer; 3. The third PMMA base layer; 4. The first particle size toughening particles; 5. The second particle size toughening particles. Detailed Embodiments

[0023] To make the purposes, technical solutions and advantages of the implementation of the present invention clearer, the following clearly and completely describes the specific implementation manners of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

[0024] Example 1

[0025] The toughening particles of the first particle size are M521, manufactured by KANEKA, with an average particle size of 250 nm. The core of the toughening particles accounts for 60% of the total weight, and the shell accounts for 40% of the total weight. The core is butyl acrylate, and the shell is a copolymer of styrene and methyl methacrylate. The refractive index of the toughening particles is 1.517.

[0026] Surface treatment of the toughening particles of the first particle size:

[0027] The surface plasmon treatment conditions are as follows: the test voltage is 8.1 kV, the frequency is 11 kHz, the electrode gap is 3 mm, the treatment time is 5 min. After the treatment, it is added to deionized water. After ultrasonic dispersion for 5 min, 0.2 parts by weight of methacryloxypropylcaged polyhedral oligomeric silsesquioxane is added, and ultrasonic dispersion is continued for 20 min. After filtration and drying, modified first-size toughening particles are obtained.

[0028] The toughening particles of the second size are M732, manufactured by KANEKA, with an average particle size of 150 nm. The core of the toughening particles accounts for 60% of the total weight, and the shell accounts for 40% of the total weight. The core is butyl acrylate, and the shell is a copolymer of styrene and methyl methacrylate. The refractive index of the toughening particles is 1.515.

[0029] Surface treatment of the toughening particles of the second size:

[0030] The surface plasmon treatment conditions are as follows: the test voltage is 8.1 kV, the frequency is 11 kHz, the electrode gap is 3 mm, the treatment time is 5 min. After the treatment, it is added to deionized water. After ultrasonic dispersion for 5 min, 0.2 parts by weight of methacryloxypropylcaged polyhedral oligomeric silsesquioxane is added, and ultrasonic dispersion is continued for 20 min. After filtration and drying, modified second-size toughening particles are obtained.

[0031] Preparation of the second PMMA base layer microparticles:

[0032] 95 parts by weight of polymethyl methacrylate resin pellets and 0.1 part of modified second-size toughening particles are dried under reduced pressure at 105 °C for 6 h, 0.1 part of a lubricant (polyester-modified silicone lubricant JW-6036, manufactured by JOUWU) is added, and granulation is carried out by extrusion at 220 °C.

[0033] Preparation of the first PMMA base layer microparticles and the third PMMA base layer microparticles:

[0034] 95 parts by weight of polymethyl methacrylate resin pellets and 0.1 part of modified first-size toughening particles are dried under reduced pressure at 105 °C for 6 h, 0.1 part of a lubricant (polyester-modified silicone lubricant JW-6036, manufactured by JOUWU) is added, and the first PMMA base layer microparticles are obtained by extrusion at 240 °C; the third PMMA base layer microparticles are obtained by the same process.

[0035] Preparation of the multi-layer PMMA optical base film:

[0036] After vacuum drying the prepared first PMMA base layer particles, second PMMA base layer particles, and third PMMA base layer particles at 110 °C for 8 h, they are supplied to the corresponding extruder for three-layer coextrusion. After extrusion into a sheet, it is cooled at 15 °C, calendered, and then longitudinally stretched 1.9 times and transversely stretched 2.1 times to make a film with an overall thickness of 40 μm, obtaining the Figure 1 multi-layer PMMA optical base film as shown.

[0037] Example 2

[0038] The toughening particles of the first particle size are M521, manufactured by KANEKA, with an average particle size of 250 nm. The core of the toughening particles accounts for 60% of the total weight, and the shell accounts for 40% of the total weight. The core is butyl acrylate, and the shell is a copolymer of styrene and methyl methacrylate. The refractive index of the toughening particles is 1.517.

[0039] Surface treatment of the toughening particles of the first particle size:

[0040] The surface plasma treatment conditions are: test voltage of 8.5 kV, frequency of 12 kHz, electrode gap of 3.5 mm, treatment time of 6 min. After treatment, it is added to deionized water, ultrasonically dispersed for 8 min, then 0.4 parts by weight of methacryloxypropylcaged polyhedral oligomeric silsesquioxane is added, and ultrasonically dispersed for another 25 min. After filtration and drying, the modified toughening particles of the first particle size are obtained.

[0041] The toughening particles of the second particle size are M732, manufactured by KANEKA, with an average particle size of 150 nm. The core of the toughening particles accounts for 60% of the total weight, and the shell accounts for 40% of the total weight. The core is butyl acrylate, and the shell is a copolymer of styrene and methyl methacrylate. The refractive index of the toughening particles is 1.515.

[0042] Surface treatment of the toughening particles of the second particle size:

[0043] The surface plasma treatment conditions are: test voltage of 8.5 kV, frequency of 12 kHz, electrode gap of 3.5 mm, treatment time of 6 min. After treatment, it is added to deionized water, ultrasonically dispersed for 8 min, then 0.4 parts by weight of methacryloxypropylcaged polyhedral oligomeric silsesquioxane is added, and ultrasonically dispersed for another 25 min. After filtration and drying, the modified toughening particles of the second particle size are obtained.

[0044] Preparation of the second PMMA base layer particles:

[0045] 100 parts by weight of polymethyl methacrylate resin pellets and 0.3 parts of the modified toughening particles of the second particle size are dried under reduced pressure at 108 °C for 7 h, 0.5 parts of a lubricant (polyester-modified silicone lubricant JW-6036, manufactured by JOUWU) is added, and granulated by extrusion at 225 °C.

[0046] Preparation of the first PMMA base microparticles and the third PMMA base microparticles:

[0047] 100 parts by weight of polymethyl methacrylate resin pellets and 0.5 part of modified first-size toughening particles are dried under reduced pressure at 108°C for 7 h, 0.5 part of a lubricant (polyester-modified silicone lubricant JW-6036, manufactured by JOUWU) is added, and extrusion is carried out at 242°C to obtain the first PMMA base microparticles; the third PMMA base microparticles are prepared by the same process.

[0048] Preparation of the multi-layer PMMA optical base film:

[0049] The prepared first PMMA base microparticles, second PMMA base microparticles, and third PMMA base microparticles are dried in vacuum at 115°C for 9 h, then supplied to the corresponding extruder for three-layer co-extrusion. After extrusion into a sheet, it is cooled at 18°C, calendered, longitudinally stretched 2.0 times and transversely stretched 2.2 times to form a film with an overall thickness of 43 μm, and then embossed on both sides and wound up.

[0050] Example 3

[0051] The toughening particles of the first size are M521, manufactured by KANEKA, with an average particle size of 250 nm. The core of the toughening particles accounts for 60% of the total weight, and the shell accounts for 40% of the total weight. The core is butyl acrylate, and the shell is a copolymer of styrene and methyl methacrylate. The refractive index of the toughening particles is 1.517.

[0052] Surface treatment of the toughening particles of the first size:

[0053] The conditions for surface plasma treatment are: test voltage of 8.8 kV, frequency of 13 kHz, electrode gap of 4 mm, treatment time of 7 min. After treatment, it is added to deionized water, ultrasonically dispersed for 10 min, then 0.5 part by weight of methacryloxypropylcaged polyhedral oligomeric silsesquioxane is added, and ultrasonically dispersed for another 30 min. After filtration and drying, modified first-size toughening particles are obtained.

[0054] The toughening particles of the second size are M732, manufactured by KANEKA, with an average particle size of 150 nm. The core of the toughening particles accounts for 60% of the total weight, and the shell accounts for 40% of the total weight. The core is butyl acrylate, and the shell is a copolymer of styrene and methyl methacrylate. The refractive index of the toughening particles is 1.515.

[0055] Surface treatment of the toughening particles of the second size:

[0056] The surface plasmon treatment conditions were as follows: the test voltage was 8.8 kV, the frequency was 13 kHz, the electrode gap was 4 mm, the treatment time was 7 min. After the treatment, it was added to deionized water, ultrasonically dispersed for 10 min, then 0.5 parts by weight of methacryloxypropylcaged polyhedral oligomeric silsesquioxane was added, and ultrasonically dispersed for another 30 min. After filtration and drying, the modified second particle size toughening particles were obtained.

[0057] Preparation of the second PMMA base layer particles:

[0058] 105 parts by weight of polymethyl methacrylate resin pellets and 0.5 parts of the modified second particle size toughening particles were dried under reduced pressure at 110 °C for 8 h, 1 part of a lubricant (polyester-modified silicone lubricant JW-6036, manufactured by JOUWU) was added, and granulated by extrusion at 230 °C.

[0059] Preparation of the first PMMA base layer particles and the third PMMA base layer particles:

[0060] 105 parts by weight of polymethyl methacrylate resin pellets and 1 part of the modified first particle size toughening particles were dried under reduced pressure at 110 °C for 8 h, 1 part of a lubricant (polyester-modified silicone lubricant JW-6036, manufactured by JOUWU) was added, and the first PMMA base layer particles were obtained by extrusion at 245 °C; the third PMMA base layer particles were prepared by the same process.

[0061] Preparation of the multi-layer PMMA optical base film:

[0062] The prepared first PMMA base layer particles, second PMMA base layer particles and third PMMA base layer particles were vacuum dried at 120 °C for 10 h, then supplied to the corresponding extruder for three-layer co-extrusion. After extrusion into a sheet, it was cooled at 20 °C, calendered, and then longitudinally stretched 2.0 times and transversely stretched 2.2 times to form a film with an overall thickness of 45 μm, and embossed on both sides and then wound up.

[0063] Comparative Example 1

[0064] Compared with Example 1, the difference in this comparative example is that the particle size of the toughening particles of the first particle size is 350 nm.

[0065] Comparative Example 2

[0066] Compared with Example 1, the difference in this comparative example is that the particle size of the toughening particles of the first particle size is 150 nm.

[0067] Comparative Example 3

[0068] Compared with Example 1, the difference in this comparative example is that the particle size of the toughening particles of the second particle size is 250 nm.

[0069] Comparative Example 4

[0070] In this comparative example, compared with Example 1, the difference is that the particle size of the toughening particles with the second particle size is 50 nm.

[0071] Comparative Example 5

[0072] In this comparative example, compared with Example 1, the difference is that the toughening particles with the first particle size and the toughening particles with the second particle size are not treated by plasma.

[0073] Comparative Example 6

[0074] In this comparative example, compared with Example 1, the difference is that methacryloxypropylcaged polysilsesquioxane is not added during the surface treatment of the toughening particles with the first particle size and the toughening particles with the second particle size.

[0075] Perform performance tests on Examples 1 to 3 and Comparative Examples 1 to 6. The test methods are as follows:

[0076] Tensile strength: Test according to the standard of GB / T 1040.3-2006, and the test speed is 50 mm / min.

[0077] Elongation at break: Test according to the standard of GB / T 1040.3-2006. During the test, the test speed is 50 mm / min.

[0078] Defect detection: Observe whether there are defects such as film breakage, rib tension lines, and film slipping in the PMMA process flow. ◎ represents that the above defects are not observed, ○ represents that there are 1 to 2 or more defects, and - represents that there are more than 3 defects.

[0079] The performance test results are shown in the following table:

[0080]

[0081] As can be seen from Table 1, the PMMA optical base films prepared in Examples 1 to 3 have good toughness and mechanical properties. At the same time, during the manufacturing process, there are no defects such as film slipping, rib tension lines, and film breakage.

[0082] In Comparative Example 1, due to the too large particle size of the particles added to the upper and lower surfaces, the surface of the film is uneven, and both the tensile strength and the elongation at break decrease. At the same time, film breakage is likely to occur.

[0083] In Comparative Example 2, due to the too small particle size of the particles added to the upper and lower surfaces, the elongation at break is poor, and a good toughening effect cannot be achieved. Moreover, the problem of film slipping is likely to occur.

[0084] In Comparative Example 3, due to the too large particle size of the particles added to the middle layer, the compatibility with the substrate is poor, and both the tensile strength and the elongation at break decrease. Moreover, defects such as film breakage and rib tension lines occur.

[0085] In Comparative Example 4, since the particle size added to the intermediate layer was too small, the toughening effect was poor, and there were defects such as film breakage and stringing.

[0086] In Comparative Example 5, the added particles were not subjected to plasma treatment, resulting in poor particle modification effect, uneven particle dispersion, poor uniformity and smoothness of the film, increased internal stress concentration, and an increase in the stringing phenomenon.

[0087] In Comparative Example 6, methacryloxypropylcaged polyhedral oligomeric silsesquioxane was not added, resulting in uneven particle dispersion and a decrease in the crosslinking degree with the polymer substrate, thereby leading to a decrease in mechanical properties, toughness, and an increase in defects such as stringing and film breakage.

[0088] The above has described the embodiments of the present invention in detail, but the present invention is not limited to the described embodiments. For those skilled in the art, without departing from the principle and spirit of the present invention, various changes, modifications, substitutions, and variations made to these embodiments still fall within the protection scope of the present invention.

Claims

1. A multilayer PMMA optical base film, characterized in that: The invention comprises a first PMMA base layer, a second PMMA base layer arranged on the surface of the first PMMA base layer, and a third PMMA base layer arranged on the second PMMA base layer away from the surface of the first PMMA base layer; toughening particles with a first particle size are arranged in the first PMMA base layer and the third PMMA base layer, and toughening particles with a second particle size are arranged in the second base layer, and the first particle size is greater than the second particle size; the toughening particles comprise an outer shell formed by copolymerization of styrene and methyl methacrylate, and an inner core formed by butyl acrylate, and the toughening particles are surface treated.

2. The multilayer PMMA optical base film according to claim 1, characterized in that: The surface treatment specifically comprises: subjecting the toughened particles to a plasma treatment under the conditions of a voltage of 8.1 to 8.8 kV and a frequency of 11 to 13 kHz for 5 to 7 minutes, subjecting the particles to ultrasonic dispersion in deionized water for 5 to 10 minutes after the treatment, adding methacryloxypropyl cage-type polysilsesquioxane and continuing ultrasonic dispersion for 20 to 30 minutes, filtering and drying after the ultrasonic dispersion is completed to obtain the toughened particles after the surface treatment.

3. The multilayer PMMA optical base film according to claim 1, characterized in that: The first particle size is 200-280 nm.

4. The multilayer PMMA optical base film according to claim 1, characterized in that: The second particle size is 100-180 nm.

5. The multilayer PMMA optical base film according to claim 1, characterized in that: The thickness of the first PMMA base layer is equal to the thickness of the third PMMA base layer.

6. A method for preparing a multilayer PMMA optical base film according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, preparing second PMMA base particles, mixing 95-105 parts by weight of polymethyl methacrylate resin pellets and 0.1-0.5 parts of second particle size toughening particles, and drying under reduced pressure at 105-110° C. for 6-8 hours, adding 0.1-1 parts of lubricant, and extruding and granulating at 220-230° C. to obtain second PMMA base particles; S2, preparing the first PMMA base particles or the third PMMA base particles, mixing 95-105 parts by weight of polymethyl methacrylate resin pellets and 0.1-0.5 parts of the first particle size toughening particles, and drying under reduced pressure at 105-110° C. for 6-8 hours, then adding 0.1-1 parts of lubricant, and extruding and granulating at 240-245° C. to obtain the first PMMA base particles or the third PMMA base particles; S3, the first PMMA base particle, the second PMMA base particle and the third PMMA base particle are vacuum dried at 110-120°C for 8-10 hours, and after drying, they are supplied to an extruder for three-layer co-extrusion into a sheet, cooled at 15-20°C, calendered, and then longitudinally stretched by 1.9-2.0 times and transversely stretched by 2.1-2.2 times to form a The multilayer PMMA optical base film according to any one of claims 1 to 5.

7. The method according to claim 6, characterized in that The lubricant is a polyester-modified silicone lubricant.

8. A polarizing plate, characterized in that: It comprises the multi-layer PMMA optical base film as described in any one of claims 1 to 5.

9. The polarizing plate according to claim 8, characterized in that: From top to bottom, it includes a functional layer, an upper PVA protective film, a PVA polarizer, a lower PVA protective film, a pressure-sensitive adhesive layer, and a release film. The upper PVA protective film and the lower PVA protective film are both the multi-layer PMMA optical base film.

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