PMMA (Polymethyl Methacrylate) film for polaroid, high-transmittance and high-polarization polaroid and preparation method of high-transmittance and high-polarization polaroid

Abstract

The invention provides a PMMA film for a polaroid, a high-transmittance high-polarization polaroid and a preparation method thereof.The preparation method of the PMMA film for the polaroid comprises the following steps that raw materials of PMMA modified resin are prepared, and the raw materials comprise, by mass, 100 parts of PMMA, 0.1-6 parts of tantalum pentoxide nanoparticles and 0.1-6 parts of silicon dioxide nanoparticles; 1-7 parts of a silane coupling agent, 1-4 parts of an ultraviolet light absorber, 0.1-10 parts of a flame retardant, 0.1-10 parts of an antioxidant and 0.1-10 parts of other auxiliary agents; the sizes of the tantalum pentoxide nanoparticles and the silicon dioxide nanoparticles are 60 to 70 nm; the raw materials are dispersed into a solvent to obtain a mixed solution, and the PMMA film with not less than 3 layers is obtained through a multi-layer casting-drawing process. According to the polaroid obtained through the technical scheme, the transmittance is improved, and meanwhile the polarization degree is kept to be 99.995% or above.

Description

Technical Field

[0001] The present invention relates to the technical field of polarizing films, and in particular to a high-transmittance and high-polarization polarizing film and a preparation method thereof. Background Art

[0002] In recent years, TV consumers' pursuit of the ultimate viewing experience has prompted LCD panel display technology to develop in the direction of high brightness and high contrast, which in turn has put forward requirements for high transmittance and high polarization degree for polarizers.

[0003] At present, the transmittance of polarizers for mainstream TVs on the market is above 42.5%, and the degree of polarization is above 99.995%. The transmittance of polarizers for high-end TVs is above 43%, and the degree of polarization is above 99.995%. Its higher optical requirements have brought higher technical challenges to polarizer manufacturers. The main product structure of polarizers that meet the above requirements is PET / PMMA+COP. COP is only supplied by one manufacturer in the world, and there is currently a shortage of material supply. Other COP materials on the market, such as SANUQI, have process limitations, so when paired with PET / PMMA, at the same transmittance level, the degree of polarization drops by about 0.002%, making it difficult to meet the above optical requirements. Summary of the invention

[0004] In view of the above technical problems, the present invention discloses a high-transmittance and high-polarization polarizer and its preparation method, the obtained polarizer has high transmittance, polarization degree meets the requirements, and has low cost. The high transmittance refers to a transmittance of more than 43%, and the high polarization refers to a polarization degree of more than 99.995%.

[0005] To this end, the technical solution adopted by the present invention is:

[0006] A method for preparing a PMMA film for a polarizer comprises the following steps:

[0007] Step S1, preparing raw materials for PMMA modified resin, the components and mass fractions of the raw materials are: 100 parts of PMMA, 0.1-6 parts of tantalum pentoxide nanoparticles, 0.1-6 parts of silicon dioxide nanoparticles, 1-7 parts of silane coupling agent, 1-4 parts of ultraviolet light absorber, 0.1-10 parts of flame retardant, 0.1-10 parts of antioxidant, and 0.1-10 parts of other additives, wherein the other additives include at least one of a leveling agent and a lubricant to improve the flatness of the film appearance; the size of the tantalum pentoxide nanoparticles and the silicon dioxide nanoparticles is 60-70 nm;

[0008] Step S2, dispersing the raw material of PMMA modified resin into a solvent to obtain a mixed liquid, and then subjecting the mixed liquid to a multi-layer casting-stretching process to obtain an n-layer PMMA film, wherein the raw material components of the PMMA modified resin used in each layer have different contents of tantalum pentoxide nanoparticles and silicon dioxide nanoparticles; wherein n is an integer not less than 3.

[0009] Generally speaking, when inorganic particles are doped into pure PMMA polymer materials, the transmittance loss will inevitably increase due to the absorption (mainly in the long wavelength range) and scattering (mainly in the short wavelength range) of the particles in the PMMA organic network. In general, the larger the size of the doped particles, the more serious the light absorption loss of the modified PMMA film. This technical solution controls the size of the nanoparticles to 60-70nm by doping high-refractive-index tantalum pentoxide nanoparticles and low-refractive-index silicon dioxide nanoparticles, thereby reducing the large light loss introduced; the nanoparticles are dispersed by a silane coupling agent, which reduces the surface energy of the particles, reduces the occurrence of agglomeration, improves their dispersibility, and improves the compatibility between the nanoparticles and PMMA. The PMMA obtained by this technical solution has a high transmittance.

[0010] As a further improvement of the present invention, n is 3, 4 or 5.

[0011] As a further improvement of the present invention, the silane coupling agent is γ-methacryloxypropyltrimethoxysilane; the use of this silane coupling agent has a good dispersion effect on tantalum pentoxide and silicon dioxide nanoparticles.

[0012] As a further improvement of the present invention, the ultraviolet light absorber is one or a mixture of two or more of benzophenone, benzotriazole and hydroxyphenyltriazine. The ultraviolet light absorber can solve the problem of poor light resistance, color tone, transparency and mechanical strength after long-term exposure to visible light.

[0013] As a further improvement of the present invention, the flame retardant is at least one of an organic phosphorus flame retardant and a silicon-containing flame retardant.

[0014] As a further improvement of the present invention, the antioxidant is at least one of antioxidant 1010, antioxidant 1076, and antioxidant 1068. This technical solution can improve the discoloration resistance under high temperature processing conditions.

[0015] As a further improvement of the present invention, the lubricant is at least one of stearic acid, stearate, and wax.

[0016] As a further improvement of the present invention, the leveling agent is at least one of silicone, acrylate, and fluorocarbon compounds.

[0017] As a further improvement of the present invention, the solvent is at least one of dichloroethane, chloroform, acetone, glacial acetic acid, tetrahydrofuran, ethyl acetate, and ethyl acetate. More preferably, the solvent is chloroform.

[0018] As a further improvement of the present invention, in the mixed solution of step S2, the mass percentage of the raw material of the PMMA modified resin is 10-20%.

[0019] As a further improvement of the present invention, in step S2, the raw material components of the PMMA modified resin used in each layer have different contents of tantalum pentoxide nanoparticles and silicon dioxide nanoparticles, so that the refractive index of each layer varies between 1.48 and 1.63.

[0020] As a further improvement of the present invention, the casting-stretching process includes the steps of casting, initial drying, online stretching, re-drying, and winding.

[0021] As a further improvement of the present invention, the initial drying temperature is 50-90°C; the online stretching ratio is 1-5 times; and the re-drying temperature is 50-90°C.

[0022] The present invention also discloses a PMMA film for a polarizer, which is prepared by using any one of the above methods for preparing a PMMA film for a polarizer.

[0023] As a further improvement of the present invention, the refractive index of the PMMA film used for the polarizer is 1.48-1.63, the total thickness is 35-45 μm, and the total light transmittance is ≥93%.

[0024] The present invention also discloses a high-transmittance and high-polarization polarizer, which comprises a release film, a pressure-sensitive adhesive layer, a SANUQI film, a PVA layer, a PMMA film and a protective film from bottom to top, wherein the PMMA film adopts the PMMA film for polarizer as described above.

[0025] The present invention also discloses a method for preparing the high-transmittance and high-polarization polarizer as described above, comprising: wet-stretching and drying the PVA, laminating it with a SANUQI film and a PMMA film by UV glue, curing it by UV light to obtain a polarizer substrate, attaching a release film coated with a pressure-sensitive adhesive, and finally attaching a protective film.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] The technical solution of the present invention adopts a specially formulated PMMA film material, which is doped with tantalum pentoxide (Ta 2 O 5 ) and silicon dioxide SiO 2Nanoparticles are used to obtain a non-uniform film structure. The film material can achieve the effect of improving transmittance through multi-layer refraction of light, which can compensate for the decrease in polarization degree of the polarizer caused by matching with SANUQI. The transmittance of the obtained polarizer is above 43%, and the polarization degree is above 99.995%, which can reach the same optical level as the mainstream PMMA+COP polarizer on the market. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a structural schematic diagram of a high-transmittance and high-polarization polarizer according to an embodiment of the present invention.

[0029] Reference numerals include:

[0030] 1-protective film, 2-PMMA film, 3-PVA layer, 4-SANUQI film, 5-pressure-sensitive adhesive layer, 6-release film. DETAILED DESCRIPTION

[0031] The preferred embodiments of the present invention are described in further detail below.

[0032] like Figure 1 As shown, a high-transmittance and high-polarization polarizer includes, from bottom to top, a release film 6, a pressure-sensitive adhesive layer 5, a SANUQI film 4, a PVA3 layer, a PMMA film 2 and a protective film 1, wherein the PMMA film 2 is mainly made of PMMA material and doped with tantalum pentoxide (Ta 2 O 5 ), silicon dioxide SiO 2 The non-uniform film structure is obtained by multi-layer casting-stretching technology. The non-uniform film structure consists of n layers of film (n≥3), and the content of tantalum pentoxide nanoparticles and silicon dioxide nanoparticles in the raw material components of PMMA modified resin used in each layer is different. The refractive index of each layer varies between 1.48 and 1.63. The total thickness is 40±5μm, and the total light transmittance is ≥93%;

[0033] Specifically, the PMMA film is prepared by the following steps:

[0034] Step S1, preparing raw materials. In terms of weight, the raw material components and their mass fractions in the PMMA modified resin are: PMMA 100 parts, tantalum pentoxide (Ta 2 O 5 ) 0.1~6 parts, silicon dioxide SiO 2 0.1-6 parts, silane coupling agent 1-7 parts, ultraviolet light absorber 1-4 parts, flame retardant 0.1-10 parts, antioxidant 0.1-10 parts, other additives 0.1-10 parts.

[0035] Among them, tantalum pentoxide (Ta 2 O 5 ), silicon dioxide SiO2 The size of the nanoparticles is controlled at 60 to 70 nm, which will not introduce large light losses.

[0036] The silane coupling agent is γ-methacryloxypropyltrimethoxysilane, which is used to increase the mutual wettability and interface bonding strength between the organic and inorganic phases.

[0037] The ultraviolet light absorber may be one or more of benzophenone series, benzotriazole series, hydroxyphenyltriazine series, etc., to solve the problem of poor light resistance, color tone, transparency and mechanical strength due to long-term exposure to visible light.

[0038] The flame retardant is a halogen-free flame retardant, such as an inorganic flame retardant, preferably one or more of an organic phosphorus flame retardant and a silicon-containing flame retardant.

[0039] The antioxidant is at least one of 1010, 1076 and 1068, which can improve the discoloration resistance under high temperature processing conditions.

[0040] Other additives include leveling agents, lubricants, etc., which are used to improve the smoothness of the film appearance.

[0041] The lubricant is at least one of stearic acid, stearate and wax.

[0042] The leveling agent is at least one of silicone, acrylate and fluorocarbon.

[0043] Step S2, preparing by solvent casting process: dispersing the above raw materials in a solvent to obtain a mixed solution, and subjecting the mixed solution to processes such as casting, primary drying, online stretching, re-drying, and winding.

[0044] The solvent can be selected from one of dichloroethane, chloroform, acetone, glacial acetic acid, tetrahydrofuran, ethyl acetate, ethyl acetate, etc., preferably chloroform;

[0045] In the mixed solution of step S2, the mass percentage of the raw material of the PMMA modified resin is 10-20%. The raw material components of the PMMA modified resin used in each layer have different contents of tantalum pentoxide nanoparticles and silicon dioxide nanoparticles, and the refractive index of each layer varies between 1.48 and 1.63.

[0046] The initial drying temperature is 50-90°C; online stretching refers to stretching in the width direction, and the stretching ratio is 1-5 times; the re-drying temperature is 50-90°C; the solvent casting machine has 3 or more feeding ports and casting ports.

[0047] The following is an explanation based on the above process combined with specific embodiments.

[0048] Example 1

[0049] In this embodiment, the raw material components and their mass fractions in the PMMA modified resin are: 100 parts of PMMA, 4 parts of silane coupling agent, 1.5 parts of ultraviolet light absorber benzophenone, 3 parts of organic phosphorus flame retardant, 2 parts of antioxidant 1010, 3 parts of leveling agent, and 3 parts of lubricant.

[0050] Tantalum pentoxide (Ta 2 O 5 ) and silicon dioxide SiO 2 The mass fraction of nanoparticles varies in each layer, see Table 1 for details. Tantalum pentoxide (Ta 2 O 5 ) and silicon dioxide SiO 2 The particle size of the nanoparticles is 60-70nm.

[0051] The above raw materials are dissolved in chloroform, and the mass percentage of the raw materials of PMMA modified resin is 10%.

[0052] The initial drying temperature is 60°C; the online stretching ratio is 5 times; the re-drying temperature is 70°C; the solvent casting machine has 3 feeding ports and casting ports.

[0053] The PMMA non-uniform film obtained has 3 layers, with a total thickness of 40±5 μm. The refractive index of each layer is shown in Table 1. The transmittance of the PMMA non-uniform film obtained is 93.28%.

[0054] The PMMA film is used to prepare a polarizer, and the steps include: wet stretching and drying PVA, laminating it with a SANUQI film and a PMMA film through UV glue, curing it through UV light to obtain a polarizer substrate, then attaching a release film coated with a pressure-sensitive adhesive, and finally attaching a protective film.

[0055] The transmittance of the polarizer prepared by using the PMMA film is 43.03%, and the polarization degree is 99.9958%.

[0056] Example 2

[0057] Based on Example 1, the difference of Example 2 is that tantalum pentoxide (Ta 2 O 5 ) and silicon dioxide SiO 2 The mass fraction of nanoparticles is different in each layer, see Table 1 for details.

[0058] The above raw materials are dissolved in chloroform, and the mass percentage of the raw materials of PMMA modified resin is 20%.

[0059] The initial drying temperature is 70°C; the online stretching ratio is 3 times; the re-drying temperature is 80°C; the solvent casting machine has 4 feeding ports and casting ports.

[0060] The PMMA non-uniform film obtained has 4 layers with a total thickness of 40±5 μm. The refractive index of each layer and the transmittance of the PMMA non-uniform film are shown in Table 1. The transmittance and polarization degree of the polarizer prepared using the PMMA film are shown in Table 1.

[0061] Example 3

[0062] Based on Example 1, the difference of Example 3 is that tantalum pentoxide (Ta 2 O 5 ) and silicon dioxide SiO 2 The mass fraction of nanoparticles is different in each layer, see Table 1 for details.

[0063] The above raw materials are dissolved in chloroform, and the mass percentage of the raw materials of PMMA modified resin is 15%.

[0064] The initial drying temperature is 80°C; the online stretching ratio is 2 times; the re-drying temperature is 90°C; the solvent casting machine has 5 feeding ports and casting ports.

[0065] The PMMA non-uniform film obtained has 5 layers with a total thickness of 40±5 μm. The refractive index of each layer and the transmittance of the PMMA non-uniform film are shown in Table 1. The transmittance and polarization degree of the polarizer prepared using the PMMA film are also shown in Table 1.

[0066] Comparative Example 1

[0067] Based on Example 1, the difference of this comparative example 1 is that tantalum pentoxide (Ta 2 O 5 ) and silicon dioxide SiO 2 The mass fraction of nanoparticles is different in each layer, see Table 1 for details.

[0068] The PMMA non-uniform film obtained has 3 layers with a total thickness of 40±5 μm. The refractive index of each layer and the transmittance of the PMMA non-uniform film are shown in Table 1. The transmittance and polarization degree of the polarizer prepared using the PMMA film are also shown in Table 1.

[0069] Comparative Example 2

[0070] In this comparative example, pure PMMA resin is used for casting and stretching to form a film with a thickness of 40±5μm. The refractive index and transmittance of the film are shown in Table 1. The steps for preparing a polarizer using the PMMA film are the same as those in Example 1. The transmittance and polarization degree of the obtained polarizer are shown in Table 1.

[0071] Table 1 Performance comparison of embodiments and comparative examples

[0072]

[0073] By comparing the above Table 1, it can be seen that the transmittance of the modified PMMA non-uniform film obtained by the technical solution of this embodiment reaches more than 93%, while the transmittance of Comparative Example 1 is only 91.38%, and the transmittance of the pure PMMA film is 92.17%. The transmittance of the polarizer of the embodiment and the transmittance of the comparative example are both 43%, with a small difference, but the polarization degree of the polarizer of the embodiment is greater than 99.995%, which is more than 0.002% higher than the polarization degree of the polarizer of the comparative example. It can be seen that the effect of increasing the transmittance by adopting the technical solution of this embodiment can compensate for the decrease in the polarization degree of the polarizer caused by the combination of SANUQI, and reach the same optical level as the mainstream PMMA+COP polarizer in the market.

[0074] The above contents are further detailed descriptions of the present invention in combination with specific preferred embodiments, and it cannot be determined that the specific implementation of the present invention is limited to these descriptions. For ordinary technicians in the technical field to which the present invention belongs, several simple deductions or substitutions can be made without departing from the concept of the present invention, which should be regarded as falling within the scope of protection of the present invention.

Claims

1. A method for preparing a PMMA film for a polarizer, characterized in that: The steps include: Step S1, preparing raw materials for PMMA modified resin, the components and mass fractions of the raw materials are: 100 parts of PMMA, 0.1-6 parts of tantalum pentoxide nanoparticles, 0.1-6 parts of silicon dioxide nanoparticles, 1-7 parts of silane coupling agent, 1-4 parts of ultraviolet light absorber, 0.1-10 parts of flame retardant, 0.1-10 parts of antioxidant, and 0.1-10 parts of other additives, wherein the other additives include at least one of a leveling agent and a lubricant; the size of the tantalum pentoxide nanoparticles and the silicon dioxide nanoparticles is 60-70 nm; Step S2, dispersing the raw material of PMMA modified resin into a solvent to obtain a mixed liquid, and then subjecting the mixed liquid to a multi-layer casting-stretching process to obtain an n-layer PMMA film, wherein the raw material components of the PMMA modified resin used in each layer have different contents of tantalum pentoxide nanoparticles and silicon dioxide nanoparticles; wherein n is an integer not less than 3.

2. The method for preparing a PMMA film for a polarizer according to claim 1, characterized in that: The silane coupling agent is γ-methacryloxypropyltrimethoxysilane; The ultraviolet light absorber is one or a mixture of two or more of benzophenone series, benzotriazole series, and hydroxyphenyltriazine series; The flame retardant is at least one of an organic phosphorus flame retardant and a silicon-containing flame retardant; The antioxidant is at least one of antioxidant 1010, antioxidant 1076, and antioxidant 1068; The lubricant is at least one of stearic acid, stearate, and wax; The leveling agent is at least one of silicone, acrylate and fluorocarbon compounds; The solvent is at least one of dichloroethane, chloroform, acetone, glacial acetic acid, tetrahydrofuran, ethyl acetate and ethyl acetate.

3. The method for preparing a PMMA film for a polarizer according to claim 2, characterized in that: In the mixed liquid of step S2, the mass percentage of the raw material of the PMMA modified resin is 10-20%; the refractive index of each layer varies between 1.48 and 1.63; n is 3, 4 or 5; the casting-stretching process includes casting, initial drying, online stretching, re-drying, and winding steps.

4. The method for preparing a PMMA film for a polarizer according to claim 2, characterized in that: The initial drying temperature is 50-90°C; the online stretching ratio is 1-5 times; and the re-drying temperature is 50-90°C.

5. A PMMA film for polarizer, characterized in that: The film is prepared by the method for preparing a PMMA film for a polarizer as claimed in any one of claims 1 to 4.

6. The PMMA film for polarizer according to claim 5, characterized in that: The total thickness of the PMMA film for polarizer is 35-45 μm.

7. A high-transmittance and high-polarization polarizer, characterized in that: It comprises, from bottom to top, a release film, a pressure-sensitive adhesive layer, a SANUQI film, a PVA layer, a PMMA film and a protective film, wherein the PMMA film is the PMMA film for polarizers as claimed in claim 5 or 6.

8. The method for preparing a high-transmittance and high-polarization polarizer according to claim 7, characterized in that: include: After PVA is wet stretched and dried, it is bonded to SANUQI film and PMMA film by UV glue, cured by UV light to obtain a polarizer substrate, and then attached with a release film coated with pressure-sensitive adhesive, and finally attached with a protective film.

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