PMMA (Polymethyl Methacrylate) optical film with low moisture permeability, preparation method of PMMA optical film and polaroid

Abstract

The invention provides a PMMA (polymethyl methacrylate) optical film with low moisture permeability, a preparation method of the PMMA optical film and a polarizer, and the PMMA optical film with low moisture permeability is prepared from the following raw materials in parts by weight: 6-8 parts of modified sericite; 80 to 100 parts of methyl methacrylate; 8-12 parts of a chlorine-containing styrene monomer; 8-12 parts of an organic solvent; 0.05 to 0.08 part of an initiator; the modified sericite is prepared from sericite modified by silane, polyethylene glycol and maleimide. According to the invention, silane-polyethylene glycol-maleimide modified sericite is copolymerized with methyl methacrylate and a chlorine-containing styrene monomer, and silane-polyethylene glycol-maleimide grafted sericite, a benzene ring and a chlorine substituent can be introduced into a polymethyl methacrylate polymer chain, so that the hydrophobic property is improved; after sericite modification, the hydrophobicity is improved, and the lamellar structure of the sericite forms a micro-nano structure on the surface of the film, so that the hydrophobic effect of the surface of the optical film can be further improved.

Description

Technical Field

[0001] The invention belongs to the technical field of optical films and relates to a low moisture permeability PMMA optical film and a preparation method thereof, and a polarizing film. Background Art

[0002] PMMA (polymethyl methacrylate) is widely used in the field of optical film materials because of its high transparency, good processing performance, excellent weather resistance and good solvent resistance. For example, it is used as a protective film for PVA in polarizers to prevent the PVA film from being eroded and damaged by the external environment, thereby ensuring the polarization performance of the polarizer.

[0003] However, PMMA has a relatively high moisture permeability, which limits its application in the polarizer industry to a certain extent. PMMA film with high moisture permeability may cause the performance of polarizer to deteriorate in a humid environment, such as reduced transmittance and reduced contrast. During long-term use, PMMA film with high moisture permeability may cause moisture accumulation inside the polarizer, which in turn causes problems such as material aging and cracking. These problems will seriously affect the durability and service life of the polarizer, so it is necessary to develop a PMMA film material with low moisture permeability to meet actual production needs. Summary of the invention

[0004] In view of the deficiencies in the prior art, the object of the present invention is to provide a low moisture permeability PMMA optical film and a preparation method thereof, and a polarizer.

[0005] To achieve this object, the present invention adopts the following technical solutions:

[0006] In a first aspect, the present invention provides a PMMA optical film with low moisture permeability. The raw materials for preparing the PMMA optical film with low moisture permeability include the following components in parts by weight:

[0007]

[0008]

[0009] The modified sericite includes silane-polyethylene glycol-maleimide modified sericite.

[0010] The present invention copolymerizes silane-polyethylene glycol-maleimide-modified sericite with methyl methacrylate and chlorostyrene monomers, and can introduce silane-polyethylene glycol-maleimide-grafted sericite, benzene rings and chlorine substituents into the polymethyl methacrylate polymer chain, thereby improving its hydrophobicity; after the sericite is modified, its hydrophobicity is improved, and its lamellar structure forms a micro-nano structure on the film surface, which can further increase the hydrophobic effect of the optical film surface. At the same time, the introduction of maleimide groups and benzene rings will increase the rigidity of PMMA segments, and the rigid lamellar structure of sericite will also restrict the movement of PMMA segments, further improving the Tg of PMMA resin.

[0011] In the present invention, the "low moisture permeability" in the low moisture permeability PMMA optical film refers to the moisture permeability of the PMMA optical film being 63-65 g / m2 when tested by the calcium chloride-permeability cup method described below. 2 / day.

[0012] In the present invention, the raw materials for preparing the low moisture permeability PMMA optical film are measured by weight, and the amount of modified sericite can be 6 parts, 6.2 parts, 6.4 parts, 6.6 parts, 6.8 parts, 7 parts, 7.2 parts, 7.4 parts, 7.6 parts, 7.8 parts, 8 parts, etc.

[0013] In the present invention, the raw materials for preparing the low moisture permeability PMMA optical film are measured by weight, and the amount of methyl methacrylate used can be 80 parts, 82 parts, 84 parts, 86 parts, 88 parts, 90 parts, 92 parts, 94 parts, 96 parts, 98 parts, 100 parts, etc.

[0014] In the present invention, the raw materials for preparing the low moisture permeability PMMA optical film are measured in parts by weight, and the amount of chlorostyrene monomer used can be 8 parts, 8.2 parts, 8.4 parts, 8.6 parts, 8.8 parts, 9 parts, 9.2 parts, 9.4 parts, 9.6 parts, 9.8 parts, 10 parts, 10.2 parts, 10.4 parts, 10.6 parts, 10.8 parts, 11 parts, 11.2 parts, 11.4 parts, 11.6 parts, 11.8 parts, 12 parts, etc.

[0015] In the present invention, the raw materials for preparing the low moisture permeability PMMA optical film are calculated by weight, and the amount of organic solvent used can be 8 parts, 8.5 parts, 9 parts, 9.5 parts, 10 parts, 10.5 parts, 11 parts, 11.5 parts, 12 parts, etc.

[0016] In the present invention, the raw materials for preparing the low moisture permeability PMMA optical film are calculated by weight, and the amount of the initiator used can be 0.05 parts, 0.06 parts, 0.07 parts, 0.08 parts, etc.

[0017] Preferably, the raw materials for preparing the modified sericite include the following components in parts by weight:

[0018] Sericite 8-10 parts;

[0019] 150-200 parts of deionized water;

[0020] Silane-polyethylene glycol-maleimide 10-20 parts.

[0021] When the present invention uses silane-polyethylene glycol-maleimide to modify sericite, the silane part in the silane-polyethylene glycol-maleimide molecule undergoes a condensation reaction with the hydroxyl group on the surface of the sericite to form a covalent bond (silicon-oxygen bond), thereby firmly bonding the silane-polyethylene glycol-maleimide molecule to the surface of the sericite, and using it to prepare a PMMA optical film can improve the compatibility with organic polymers such as methyl methacrylate. The improvement in compatibility helps to reduce the agglomeration phenomenon of sericite in methyl methacrylate, making it more evenly dispersed, and the hydrophobicity of the modified sericite is improved, and it is evenly dispersed in the copolymer to form an effective barrier layer, which is conducive to reducing the moisture permeability of the PMMA optical film.

[0022] Preferably, the amount of the modified sericite prepared by raw materials can be 8 parts, 8.2 parts, 8.4 parts, 8.6 parts, 8.8 parts, 9 parts, 9.2 parts, 9.4 parts, 9.6 parts, 9.8 parts, 10 parts, etc., in terms of weight.

[0023] Preferably, the amount of deionized water used in the preparation raw materials of the modified sericite can be 150 parts, 155 parts, 160 parts, 165 parts, 170 parts, 175 parts, 180 parts, 185 parts, 190 parts, 195 parts, 200 parts, etc., based on parts by weight.

[0024] Preferably, the amount of silane-polyethylene glycol-maleimide used in the preparation of the modified sericite can be 10 parts, 10.5 parts, 11 parts, 11.5 parts, 12 parts, 12.5 parts, 13 parts, 13.5 parts, 14 parts, 14.5 parts, 15 parts, 15.5 parts, 16 parts, 16.5 parts, 17 parts, 17.5 parts, 18 parts, 18.5 parts, 19 parts, 19.5 parts, 20 parts, etc., based on parts by weight.

[0025] Preferably, the modified sericite is prepared by the following method:

[0026] The modified sericite is obtained by mixing, dispersing and post-treating sericite, deionized water and silane-polyethylene glycol-maleimide.

[0027] Preferably, the dispersion temperature is 60-70°C, such as 60°C, 65°C, 70°C, etc.

[0028] Preferably, the dispersion rotation speed is 100-200 rpm, for example, 100 rpm, 120 rpm, 140 rpm, 160 rpm, 180 rpm, 200 rpm, etc.

[0029] Preferably, the dispersion time is 2 to 3 hours, such as 2 hours, 2.5 hours, 3 hours, etc.

[0030] Preferably, the post-treatment includes filtering, washing and drying.

[0031] Preferably, the sericite further comprises the following pretreatment steps before mixing:

[0032] Keep the sericite at 300-350°C (e.g., 300°C, 310°C, 320°C, 330°C, 340°C, 350°C, etc.) for 1-2h (e.g., 1h, 1.5h, 2h, etc.), increase the temperature to 400-450°C (e.g., 400°C, 410°C, 420°C, 430°C, 440°C, 450°C, etc.), keep the temperature for 1-2h (e.g., 1h, 1.5h, 2h, etc.), then increase the temperature to 500-550°C (e.g., 500°C, 510°C, 520°C, 530°C, 540°C, 550°C, etc.), keep the temperature for 1-2h (e.g., 1h, 1.5h, 2h, etc.), and cool naturally;

[0033] The obtained sericite is added to a ball mill containing ball mill beads. After the ball mill is evacuated, it is ball milled at 110-120° C. (for example, 110° C., 115° C., 120° C., etc.) and a rotation speed of 500-580 rpm (for example, 500 rpm, 510 rpm, 520 rpm, 530 rpm, 540 rpm, 550 rpm, 560 rpm, 570 rpm, 580 rpm, etc.) for 1-2 h (for example, 1 h, 1.5 h, 2 h, etc.), cooled, and the vacuum is removed.

[0034] The sericite added in the present invention is a layered silicate mineral, which has excellent unit sheet performance and stable chemical properties. The pretreatment step adopts a process of gradually increasing temperature, naturally cooling, and vacuum ball milling, which can remove moisture and volatile impurities in the sericite to make the structure of the sericite more stable. The high-temperature treatment can further improve the crystallinity and surface activity of the sericite, providing better conditions for subsequent reactions and modifications. The ball milling process can further refine the sericite particles and increase their specific surface area and active sites, which is beneficial to subsequent reactions and modifications and improves the grafting modification effect.

[0035] Preferably, the ball milling beads include zirconium oxide ball milling beads.

[0036] As a preferred technical solution of the present invention, the modified sericite is prepared by the following method:

[0037] S1. Pretreatment of sericite: keep the sericite at 300-350°C for 1-2h, raise the temperature to 400-450°C, keep it for 1-2h, raise the temperature to 500-550°C, keep it for 1-2h, and cool it naturally;

[0038] The obtained sericite is added into a ball milling jar filled with zirconium oxide ball milling beads, and after the ball milling jar is evacuated, the jar is ball milled at 110-120° C. and a speed of 500-580 rpm for 1-2 hours, the temperature is lowered, and the vacuum is removed;

[0039] S2. Mix the sericite obtained in step S1, deionized water, and silane-polyethylene glycol-maleimide, disperse them at 60-70° C. and 100-200 rpm for 2-3 hours, filter, wash, and dry to obtain the modified sericite.

[0040] Preferably, the particle size of the modified sericite is 100-500 nm, for example, 100 nm, 150 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, etc.

[0041] Preferably, the chlorinated styrene monomer includes any one of p-chloromethylstyrene, α-chlorostyrene, β-chlorostyrene, o-chlorostyrene and p-chlorostyrene, or a combination of at least two thereof.

[0042] Preferably, the organic solvent comprises toluene.

[0043] Preferably, the initiator comprises dibenzoyl peroxide.

[0044] In a second aspect, the present invention provides a method for preparing a PMMA optical film with low moisture permeability as described in the first aspect, the preparation method comprising the following steps:

[0045] The modified sericite, methyl methacrylate, chlorostyrene monomer, organic solvent and initiator are mixed in a prescribed amount, an inert gas is continuously introduced into the system to remove oxygen, the system is heated and reacted, and the polymer solution after the reaction is devolatilized and pelletized to obtain a resin material;

[0046] The resin material is dried, melted and extruded, cooled and formed, and then longitudinally stretched and transversely stretched to obtain the PMMA optical film with low moisture permeability.

[0047] Preferably, the inert gas comprises nitrogen.

[0048] Preferably, the time for continuously introducing the inert gas for deoxygenation is 1 to 2 hours, such as 1 hour, 1.5 hours, 2 hours, etc.

[0049] Preferably, the heating is carried out by heating to 105 - 120 °C, such as 105 °C, 110 °C, 115 °C, 120 °C, etc.

[0050] Preferably, the pressure of the reaction is 0.2 - 0.25 MPa, such as 0.2 MPa, 0.22 MPa, 0.23 MPa, 0.25 MPa, etc., and the reaction time is 2 - 3 h, such as 2 h, 2.5 h, 3 h, etc.

[0051] Preferably, the devolatilization is carried out in a devolatilization extruder.

[0052] Preferably, the temperature of the devolatilization is 240 - 245 °C, such as 240 °C, 242 °C, 243 °C, 245 °C, etc.

[0053] Preferably, the melt extrusion is carried out in a single - screw extruder.

[0054] Preferably, the stretching multiple in the longitudinal direction is 2 - 3.5 times, such as 2 times, 2.5 times, 3 times, 3.5 times, etc.

[0055] Preferably, the stretching multiple in the transverse direction is 2 - 3.5 times, such as 2 times, 2.5 times, 3 times, 3.5 times, etc.

[0056] Preferably, the thickness of the low - moisture - permeability PMMA optical film is 35 - 45 μm, such as 35 μm, 38 μm, 40 μm, 42 μm, 43 μm, 45 μm, etc.

[0057] In a third aspect, the present invention provides a polarizer, which comprises the low - moisture - permeability PMMA optical film as described in the first aspect or the low - moisture - permeability PMMA optical film prepared by the preparation method as described in the second aspect.

[0058] Compared with the prior art, the present invention has at least the following beneficial effects:

[0059] In the present invention, the silane - polyethylene glycol - maleimide - modified sericite is copolymerized with methyl methacrylate and chlorostyrene monomers, so that the sericite grafted with silane - polyethylene glycol - maleimide, benzene rings and chlorine substituents can be introduced into the poly(methyl methacrylate) polymer chain, and its hydrophobic property is improved; after the sericite is modified, its hydrophobicity is improved, and its lamellar structure forms a micro - nano structure on the film surface, which can further increase the hydrophobic effect of the optical film surface. At the same time, the introduction of maleimide groups and benzene rings will increase the rigidity of the PMMA chain segments, and the rigid lamellar structure of sericite will also restrict the movement of the PMMA chain segments, further increasing the Tg of the PMMA resin. Detailed embodiments

[0060] The technical solution of the present invention is further described below by specific implementation methods. It should be understood by those skilled in the art that the embodiments are only to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0061] Unless otherwise specified, some of the raw materials used in the following examples and comparative examples of the present invention are as follows:

[0062] Sericite: purchased from Chuzhou Wanqiao Sericite Co., Ltd., model: CJ-A6, average particle size ≤10μm;

[0063] Silane-polyethylene glycol-maleimide: purchased from Shanghai Yuanye Biotechnology Co., Ltd., S29200.

[0064] Example 1

[0065] In this embodiment, a low moisture permeability PMMA optical film is provided, and a preparation method thereof comprises the following steps:

[0066] S1. Pretreatment of Sericite:

[0067] Put 8 parts of sericite mica into an oven, set the oven temperature to 300°C, keep it at this temperature for 1 hour, increase the temperature to 400°C, keep it for 1 hour, increase the temperature to 500°C, keep it for 1 hour, turn off the oven, and cool it naturally;

[0068] The obtained sericite was added into a ball mill filled with zirconium oxide ball milling beads, and the ball mill was evacuated, and then ball milled at 110° C. and 500 rpm for 1 h, cooled, and the vacuum was removed for later use;

[0069] S2. Modification of Sericite:

[0070] The sericite obtained in step S1 is added into a blender, and 150 parts of deionized water and 10 parts of silane-polyethylene glycol-maleimide are added thereto, and the mixture is dispersed at 60° C. and 100 rpm for 2 hours, and then filtered, washed, and dried to obtain modified sericite (with a particle size of 100 nm) for later use;

[0071] S3. Preparation of optical film:

[0072] 6 parts of modified sericite prepared from S2, 80 parts of methyl methacrylate, 8 parts of p-chloromethylstyrene, 8 parts of toluene, and 0.05 parts of dibenzoyl peroxide were added to the reaction kettle, and the mixture was stirred thoroughly and then continuously heated with N 2 Deoxygenate for 1 hour, stir evenly, heat to 105°C, react for 2 hours under the condition of 0.2MPa pressure in the kettle, transport the polymer solution after the reaction to the devolatilization extruder at 240°C, devolatilize and pelletize to obtain resin material;

[0073] After drying the resin material, it is melt-extruded through a single-screw extruder, formed after cooling by a cooling roll, longitudinally stretched 2.0 times, and transversely stretched 2.0 times to produce an optical film with a thickness of 35 μm.

[0074] Example 2

[0075] In this example, a low moisture permeability PMMA optical film is provided, and the preparation method includes the following steps:

[0076] S1. Pretreatment of sericite:

[0077] Put 9 parts of sericite into an oven, set the oven temperature to 320 °C, keep it at this temperature for 1.5 h, raise the temperature to 420 °C, keep it for 1.5 h, then raise the temperature to 530 °C, keep it for 1.5 h, turn off the oven, and let it cool naturally;

[0078] Add the obtained sericite to a ball mill tank equipped with zirconia ball milling beads. After evacuating the ball mill tank, ball mill at 115 °C at a rotation speed of 540 rpm for 1.5 h, cool down, remove the vacuum, and set aside;

[0079] S2. Modification treatment of sericite:

[0080] Add the sericite obtained in step S1 to a blender, add 180 parts of deionized water and 15 parts of silane-polyethylene glycol-maleimide thereto, disperse at 65 °C and 150 rpm for 2.5 h, filter, wash, and dry to obtain modified sericite (particle size of 200 nm), and set aside;

[0081] S3. Preparation of the optical film:

[0082] Add 7 parts of modified sericite, 90 parts of methyl methacrylate, 10 parts of p-chloromethylstyrene, 10 parts of toluene, and 0.07 parts of dibenzoyl peroxide prepared in S2 by weight to a reaction kettle, stir well and mix evenly, and then continuously pass N 2 Deoxygenate for 1.2 h, stir evenly, heat to 110 °C, react for 2.5 h under the condition that the pressure in the kettle is 0.22 MPa, then transport the reacted polymer solution to a devolatilization extruder at a temperature of 243 °C, devolatilize and pelletize to obtain a resin material;

[0083] After drying the resin material, it is melt-extruded through a single-screw extruder, formed after cooling by a cooling roll, longitudinally stretched 2.8 times, and transversely stretched 3.0 times to produce an optical film with a thickness of 40 μm.

[0084] Example 3

[0085] In this example, a low moisture permeability PMMA optical film is provided, and the preparation method includes the following steps:

[0086] S1. Pretreatment of Sericite:

[0087] Put 10 parts of sericite mica into an oven, set the oven temperature to 350°C, keep it at this temperature for 2 hours, increase the temperature to 450°C, keep it for 2 hours, increase the temperature to 550°C, keep it for 2 hours, turn off the oven, and cool it naturally;

[0088] The obtained sericite was added into a ball mill filled with zirconium oxide ball milling beads, and after the ball mill was evacuated, it was ball milled at 120° C. and 580 rpm for 2 h, cooled, and the vacuum was removed for later use;

[0089] S2. Modification of Sericite:

[0090] The sericite obtained in step S1 is added into a blender, and 200 parts of deionized water and 20 parts of silane-polyethylene glycol-maleimide are added thereto, and the mixture is dispersed at 70° C. and 200 rpm for 3 hours, and then filtered, washed, and dried to obtain modified sericite (with a particle size of 500 nm) for later use;

[0091] S3. Preparation of optical film:

[0092] 8 parts of modified sericite prepared from S2, 100 parts of methyl methacrylate, 12 parts of p-chloromethylstyrene, 12 parts of toluene, and 0.08 parts of dibenzoyl peroxide were added to the reaction kettle, and the mixture was stirred thoroughly and then continuously heated to 400 °C. 2 Deoxygenate for 2 hours, stir evenly, heat to 120°C, react for 3 hours at a pressure of 0.25 MPa in the autoclave, transport the polymer solution after the reaction to a devolatilization extruder at 245°C, devolatilize and pelletize to obtain a resin material;

[0093] After the resin material is dried, it is melt-extruded through a single-screw extruder, cooled by a cooling roller, and then formed. It is stretched 3.5 times in the longitudinal direction and 3.5 times in the transverse direction to form an optical film with a thickness of 45 μm.

[0094] Example 4

[0095] The difference between this embodiment and embodiment 1 is that the p-chloromethylstyrene in step S3 is replaced by p-chlorostyrene in equal parts by weight.

[0096] Example 5

[0097] The only difference between this embodiment and embodiment 1 is that the pretreatment step of sericite is not included.

[0098] Comparative Example 1

[0099] The only difference between this comparative example and Example 1 is that the modification treatment step of sericite is not included, that is, sericite is directly added in S3.

[0100] Comparative Example 2

[0101] The only difference between this comparative example and Example 1 is that the addition of sericite is missing, steps S1 and S2 are omitted, and in step S3, the modified sericite is replaced by silane-polyethylene glycol-maleimide in equal parts by weight.

[0102] Comparative Example 3

[0103] The only difference between this comparative example and Example 1 is that the amount of modified sericite used in step S3 is 5 parts.

[0104] Comparative Example 4

[0105] The only difference between this comparative example and Example 1 is that the amount of modified sericite used in step S3 is 10 parts.

[0106] The PMMA optical films provided in the examples and comparative examples were tested for performance, and the testing method was as follows:

[0107] (1) Test method for glass transition temperature (Tg) of PMMA optical film:

[0108] About 15 g of sample was taken and the glass transition temperature Tg (° C.) was measured using a differential scanning calorimeter DSC under the conditions of a nitrogen flow rate of 30 mL / min and a heating rate of 20° C. / min in accordance with JIS-K7121.

[0109] (2) PMMA optical film water vapor transmission rate test method:

[0110] The calcium chloride-permeable cup method is adopted. 30g of calcium chloride is placed in the permeable cup, and the mouth of the permeable cup is covered with the optical film of the present invention. The test is carried out for 24 hours at a temperature of 40°C and a humidity of 90% RH. The weight of calcium chloride before and after the test is measured. The moisture permeability = the weight difference of calcium chloride before and after the test / the area of ​​the cup mouth, in g / m 2 / day.

[0111] (3) Water contact angle test method:

[0112] The contact angle meter Dmo-502 manufactured by Kyowa was used to measure the angle by dropping water on the surface of the optical film.

[0113] The performance test results are shown in Table 1.

[0114] Table 1

[0115] project Tg(℃) <![CDATA[Water vapor transmission rate (g / m 2 / day)]]> Water contact angle (°) Example 1 123 65 90 Example 2 122 64 91 Example 3 122 63 91 Example 4 123 63 90 Example 5 114 102 75 Comparative Example 1 113 130 68 Comparative Example 2 110 135 69 Comparative Example 3 109 135 68 Comparative Example 4 112 131 67

[0116] It can be seen from Table 1 that the PMMA optical films provided in Examples 1-4 of the present invention all have low moisture permeability (moisture permeability: 63-65 g / m 2 / day), and a high water contact angle (90°-91°), which improves the hydrophobicity of the PMMA optical film and has a high glass transition temperature (122-123°C).

[0117] Compared with Example 1, Example 5 lacks the pretreatment step of sericite, resulting in high impurity content, few surface active sites, and poor grafting modification effect of sericite, which ultimately leads to increased moisture permeability and reduced hydrophobicity of the PMMA optical film.

[0118] Compared with Example 1, Comparative Example 1 lacks the step of using silane-polyethylene glycol-maleimide to modify the sericite, resulting in poor compatibility of sericite with organic polymers such as methyl methacrylate, serious agglomeration of sericite, uneven dispersion, and low hydrophobicity, which ultimately leads to a significant increase in the moisture permeability of the PMMA optical film and a significant decrease in the hydrophobicity.

[0119] Compared with Example 1, due to the lack of the addition of sericite, Comparative Example 2 cannot form a micro-nano structure on the surface of the PMMA optical film, and the hydrophobic effect of the optical film is significantly deteriorated, which also affects the Tg of the PMMA resin and reduces the Tg.

[0120] Compared with Example 1, since too little modified sericite is added in Comparative Example 3, its distribution in the polymer matrix is ​​not uniform enough to form an effective hydrophobic layer, thus affecting the hydrophobic effect.

[0121] Compared with Example 1, in Comparative Example 4, due to the excessive addition of modified sericite, the surface roughness of the membrane material is excessively increased, resulting in uneven surface morphology, which is not conducive to the improvement of hydrophobic performance.

[0122] The applicant declares that the present invention uses the above embodiments to illustrate the low moisture permeability PMMA optical film and its preparation method and polarizer of the present invention, but the present invention is not limited to the above embodiments, that is, it does not mean that the present invention must rely on the above embodiments to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of various raw materials of the product of the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

Claims

1. A low moisture permeability PMMA optical film, characterized in that: The raw materials for preparing the low moisture permeability PMMA optical film include the following components in parts by weight: The modified sericite includes silane-polyethylene glycol-maleimide modified sericite.

2. The low moisture permeability PMMA optical film according to claim 1, characterized in that: The raw materials for preparing the modified sericite include the following components in parts by weight: Sericite 8-10 parts; 150-200 parts of deionized water; Silane-polyethylene glycol-maleimide 10-20 parts.

3. The low moisture permeability PMMA optical film according to claim 1 or 2, characterized in that: The modified sericite is prepared by the following method: The modified sericite is obtained by mixing, dispersing and post-treating sericite, deionized water and silane-polyethylene glycol-maleimide; Preferably, the dispersion temperature is 60-70°C; Preferably, the dispersion speed is 100 to 200 rpm; Preferably, the dispersion time is 2 to 3 hours; Preferably, the post-treatment includes filtering, washing and drying.

4. The low moisture permeability PMMA optical film according to claim 3, characterized in that: The sericite also includes the following pre-treatment steps before mixing: Keep the sericite at 300-350°C for 1-2 hours, raise the temperature to 400-450°C, keep it for 1-2 hours, raise the temperature to 500-550°C, keep it for 1-2 hours, and cool it naturally; The obtained sericite is added to a ball mill filled with ball mill beads, and after the ball mill is evacuated, the ball mill is milled at 110-120° C. and a speed of 500-580 rpm for 1-2 hours, the temperature is lowered, and the vacuum is removed; Preferably, the ball milling beads include zirconium oxide ball milling beads.

5. The low moisture permeability PMMA optical film according to any one of claims 1 to 4, characterized in that: The modified sericite is prepared by the following method: S1. Pretreatment of sericite: keep the sericite at 300-350°C for 1-2h, raise the temperature to 400-450°C, keep it for 1-2h, raise the temperature to 500-550°C, keep it for 1-2h, and cool it naturally; The obtained sericite is added into a ball milling jar filled with zirconium oxide ball milling beads, and after the ball milling jar is evacuated, the jar is ball milled at 110-120° C. and a speed of 500-580 rpm for 1-2 hours, the temperature is lowered, and the vacuum is removed; S2. Mix the sericite obtained in step S1, deionized water, and silane-polyethylene glycol-maleimide, disperse them at 60-70° C. and 100-200 rpm for 2-3 hours, filter, wash, and dry to obtain the modified sericite.

6. The low moisture permeability PMMA optical film according to any one of claims 1 to 5, characterized in that: The particle size of the modified sericite is 100-500nm.

7. The low moisture permeability PMMA optical film according to any one of claims 1 to 6, characterized in that: The chlorinated styrene monomer includes any one of p-chloromethylstyrene, α-chlorostyrene, β-chlorostyrene, o-chlorostyrene, and p-chlorostyrene, or a combination of at least two thereof; Preferably, the organic solvent comprises toluene; Preferably, the initiator comprises dibenzoyl peroxide.

8. A method for preparing a PMMA optical film with low water vapor permeability as claimed in any one of claims 1 to 7, characterized in that: The preparation method comprises the following steps: The modified sericite, methyl methacrylate, chlorostyrene monomer, organic solvent and initiator are mixed in a prescribed amount, an inert gas is continuously introduced into the system to remove oxygen, the system is heated and reacted, and the polymer solution after the reaction is devolatilized and pelletized to obtain a resin material; The resin material is dried, melted and extruded, cooled and formed, and then longitudinally stretched and transversely stretched to obtain the PMMA optical film with low moisture permeability.

9. The preparation method according to claim 8, characterized in that: The inert gas includes nitrogen; Preferably, the time for continuously introducing inert gas to deoxygenate is 1 to 2 hours; Preferably, the heating is heating to 105-120°C; Preferably, the reaction pressure is 0.2-0.25 MPa, and the reaction time is 2-3 h; Preferably, the devolatilization is carried out in a devolatilization extruder; Preferably, the devolatilization temperature is 240-245°C; Preferably, the melt extrusion is carried out in a single screw extruder; Preferably, the longitudinal stretching multiple is 2 to 3.5 times; Preferably, the transverse stretching multiple is 2 to 3.5 times; Preferably, the thickness of the low moisture permeability PMMA optical film is 35-45 μm.

10. A polarizer, characterized in that: The polarizer comprises the low moisture permeability PMMA optical film according to any one of claims 1 to 7 or comprises the low moisture permeability PMMA optical film prepared according to the preparation method according to claim 8 or 9.

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