Primer coating liquid, PMMA (polymethyl methacrylate) film as well as preparation method and application of PMMA film

Abstract

The invention provides primer coating liquid, a PMMA (polymethyl methacrylate) film as well as a preparation method and application of the PMMA film. The primer coating liquid comprises the following components in parts by weight: 2-6 parts of waterborne polyurethane resin; 1 to 5 parts of hydrophobic polyurethane resin; 2-8 parts of a cross-linking agent; 0.5 to 2 parts of a compatilizer; 0.1 to 0.5 part of a dispersant; 1-6 parts of silicon dioxide particles; and 100 to 120 parts of water. The waterborne polyurethane resin and the hydrophobic polyurethane resin are matched, so that the base film is endowed with more excellent water resistance and chemical stability, the service life of the base film is effectively prolonged, and the overall durability and reliability of the base film are improved; the coating liquid shows excellent dispersity, and is beneficial to improving the transmittance of a base film, so that the light transmission is more efficient.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical materials, and particularly relates to a primer coating solution, a PMMA film, and their preparation methods and applications. Background Art

[0002] PMMA (polymethyl methacrylate) optical film is a polymer material with excellent optical properties, having advantages such as high transparency, low birefringence, and good weather resistance. As a protective film for PVA in polarizers, it is gradually replacing traditional TAC films. However, currently, PMMA films often have difficulty meeting the growing demand in terms of water barrier performance. Some conventional PMMAs have a relatively high water permeability in high-temperature and high-humidity environments, and cannot provide sufficient protection for the devices or products in which they are applied. For example, in some common polymer-based optical films, due to the limitations of their molecular structure and microscopic morphology, water molecules can relatively easily penetrate through the film layer, resulting in a high risk of moisture absorption for the devices during use. At the same time, in the pursuit of high water barrier performance, the optical properties of the optical film and its adhesion performance with PVA cannot be ignored.

[0003] A primer layer is attached to the surface of PMMA, mainly used to enhance the adhesion between the optical film and the substrate or other functional layers. For example, in the manufacture of polarizers, the primer can improve the adhesion between PMMA and polyvinyl alcohol (PVA). However, it cannot be ignored that traditional primer layers usually do not have good hydrophobicity and perform poorly in waterproofing, and cannot effectively prevent moisture from damaging the optical film. In order to effectively solve the deficiencies of PMMA films in terms of water barrier performance while ensuring that their optical properties and adhesion performance with PVA are not affected, it is particularly urgent and necessary to invent a primer with good hydrophobicity. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the purpose of the present invention is to provide a primer coating solution, a PMMA film, and their preparation methods and applications.

[0005] To achieve the purpose of this invention, the following technical solutions are adopted:

[0006] On the one hand, the present invention provides a primer coating solution, and the primer coating solution comprises the following components in parts by weight:

[0007]

[0008] In the present invention, the main resins selected are aqueous polyurethane resin and hydrophobic polyurethane resin. As the main components of the coating, the aqueous polyurethane resin has good film-forming properties and can form a continuous and uniform thin film on the substrate surface, providing the basic properties of the coating; the addition of hydrophobic polyurethane can effectively improve the hydrophobicity of the coating and help enhance the coating's resistance to chemical substances; the compatibilizer molecules have hydrophilic and hydrophobic parts, which can act as a bridge between the two resins, enabling them to be uniformly mixed together to form a stable system. A dispersant is added to ensure the uniform dispersion of the hydrophobic polyurethane and silica particles in the system, which is beneficial to the uniformity and stability of the functional coating. The coating liquid of the present invention has good film-forming properties, transparency, is non-flammable, non-toxic and has low volatility, is environmentally friendly, and has higher safety during production and use.

[0009] In the present invention, the content of the aqueous polyurethane resin in the primer coating liquid can be 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts, 5 parts, 5.5 parts or 6 parts, the content of the hydrophobic polyurethane resin can be 1 part, 1.5 parts, 2 parts, 2.5 parts, 3 parts, 3.5 parts, 4 parts, 4.5 parts or 5 parts, the content of the cross-linking agent can be 2 parts, 3 parts, 4 parts, 5 parts, 6 parts, 7 parts or 8 parts, the content of the compatibilizer can be 0.5 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, 1.8 parts or 2 parts, the content of the dispersant can be 0.1 parts, 0.2 parts, 0.3 parts, 0.4 parts or 0.5 parts, the content of the silica particles is 1 part, 2 parts, 3 parts, 4 parts, 5 parts or 6 parts, and the content of the pure water is 100 parts, 103 parts, 105 parts, 108 parts, 110 parts, 115 parts, 118 parts or 120 parts.

[0010] Preferably, the aqueous polyurethane resin is a polymer having a hydroxyl group or a tertiary amino group formed by the reaction of a polyester polyol and an isocyanate.

[0011] More preferably, the aqueous polyurethane resin is copolymerized from 5-amino-1,3,3-trimethyl-cyclohexanemethylamine, Α-hydro-Ω-hydroxy-poly(oxy-1,4-butylene) and 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane.

[0012] Preferably, the hydrophobic polyurethane resin is one or at least two combinations of fluorinated polyurethane, organosilicon-modified polyurethane, aliphatic isocyanate-based polyurethane, long-chain alkyl-modified polyurethane or polysiloxane-modified polyurethane, and polysiloxane-modified polyurethane is further preferred.

[0013] Preferably, the cross-linking agent is selected from one or at least two combinations of oxazoline, acrylamide or carbodiimide.

[0014] Preferably, the compatibilizer is one or a combination of at least two of maleic anhydride grafted polymers, polyolefin copolymers, amino silane coupling agents, polyester-polyether polyol block copolymers, or hydrophobic polyurethane-polyurethane block copolymers.

[0015] Preferably, the dispersant is one or a combination of at least two of acrylate dispersants, high molecular weight block copolymer dispersants, or polyether modified polysiloxane dispersants.

[0016] Preferably, the particle size of the silicon dioxide particles is 30 - 100 nm, such as 30 nm, 35 nm, 40 nm, 45 nm, 50 nm, 55 nm, 60 nm, 70 nm, 80 nm, 90 nm, or 100 nm.

[0017] Preferably, the water is water sterilized by ultraviolet light with a wavelength of 180 - 254 nm (such as 180 nm, 185 nm, 190 nm, 195 nm, 200 nm, or 250 nm, etc.).

[0018] Preferably, the resistivity of the water is 12 - 18 MΩ·cm, such as 12 MΩ·cm, 13 MΩ·cm, 14 MΩ·cm, 15 MΩ·cm, 16 MΩ·cm, 17 MΩ·cm, or 18 MΩ·cm.

[0019] In the present invention, the water sterilized by ultraviolet light and the resistivity of the water are controlled to ensure the purity of the water, maintain the aseptic state of the solution, prevent the solution from deteriorating due to microbial contamination, and ensure the stability of each component and the controllability of the reaction.

[0020] On the other hand, the present invention provides a method for preparing the primer coating solution as described above, and the preparation method includes the following steps:

[0021] S1. Mix the silicon dioxide particles, water, and dispersant to obtain a first mixed solution;

[0022] S2. Add the aqueous polyurethane resin and the compatibilizer to the first mixed solution and mix to obtain a second mixed solution;

[0023] S3. Add the hydrophobic polyurethane resin to the second mixed solution and mix to obtain a third mixed solution;

[0024] S4. Add the crosslinking agent to the third mixed solution, mix, and filter to obtain the primer coating solution.

[0025] In the present invention, through the above preparation method, the full dispersion of the silicon dioxide particles can be achieved without agglomeration, the phase separation of the aqueous polyurethane resin and the hydrophobic polyurethane resin can be prevented, and the quality of the coating film obtained using the primer coating solution can be ensured.

[0026] In the present invention, in step S1, the silica particles are first dispersed to avoid affecting the subsequent film coating performance and appearance defects due to silica agglomeration. In step S2, the aqueous polyurethane resin and the compatibilizer are first added to the dispersion of silica, and then in step S3, the hydrophobic polyurethane resin is added. At this time, the aqueous polyurethane resin and the hydrophobic polyurethane resin will not phase-separate and will not affect the film coating quality. In step S4, the cross-linking agent is added to avoid a sudden increase in viscosity caused by premature addition of the cross-linking agent, which may affect the subsequent coating operation and film coating quality.

[0027] In the present invention, if all the raw materials are simply mixed simultaneously, the silica particles will not be effectively dispersed, the two polyurethane resins will phase-separate, and the adhesion will decrease.

[0028] Preferably, the mixing in step S1 is achieved by the following operation: stirring at a speed of 200 rpm to 500 rpm (such as 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm or 500 rpm) for 20 min to 40 min (such as 20 min, 25 min, 28 min, 30 min, 35 min, 38 min or 40 min).

[0029] Preferably, the mixing in step S2 is achieved by the following operation: stirring at a speed of 200 rpm to 500 rpm (such as 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm or 500 rpm) for 20 min to 60 min (such as 20 min, 25 min, 28 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min).

[0030] Preferably, the mixing in step S3 is achieved by the following operation: stirring at a speed of 300 rpm to 600 rpm (such as 300 rpm, 350 rpm, 400 rpm, 450 rpm, 500 rpm, 550 rpm or 600 rpm) for 30 min to 70 min (such as 30 min, 35 min, 40 min, 45 min, 50 min, 55 min, 60 min, 65 min, 68 min or 70 min).

[0031] Preferably, the mixing in step S4 is achieved by the following operation: stirring at a rotation speed of 100 rpm to 500 rpm (such as 100 rpm, 200 rpm, 250 rpm, 300 rpm, 350 rpm, 400 rpm, 450 rpm or 500 rpm) for 20 min to 40 min (such as 20 min, 25 min, 30 min, 35 min or 40 min).

[0032] Preferably, the filtration in step S4 is achieved by inner circulation filtration with a filter having a filter element pore size of 1 μm to 10 μm (such as 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm or 10 μm) for 20 to 60 min (such as 20 min, 25 min, 28 min, 30 min, 35 min, 40 min, 45 min, 50 min, 55 min or 60 min).

[0033] Preferably, after the filtration in step S4, it is left standing in a low-pressure environment of -0.1 Mpa to 0 Mpa for 3 to 6 h (such as 3 h, 3.5 h, 4 h, 4.5 h, 5 h, 5.5 h or 6 h). Wait until the bubbles completely disappear to obtain the primer coating solution.

[0034] On the other hand, the present invention provides a PMMA film, which includes a PMMA substrate and a primer coating solution layer provided on the surface of the PMMA substrate, and the primer coating solution layer is prepared from the primer coating solution as described above.

[0035] On the other hand, the present invention provides a method for preparing the PMMA film as described above, and the preparation method includes the following steps:

[0036] The primer coating solution is uniformly coated on the surface of the PMMA substrate and dried to obtain the PMMA film.

[0037] Preferably, the PMMA substrate is surface-treated before coating the primer coating solution.

[0038] Preferably, the surface treatment is to corona-treat the surface of the PMMA substrate with a power of 0.1 KW to 6 KW (such as 0.1 KW, 0.5 KW, 1 KW, 1.5 KW, 2 KW, 2.5 KW, 3 KW, 3.5 KW, 4 KW, 4.5 KW, 5 KW, 5.5 KW or 6 KW) to reduce the contact angle of the surface of the PMMA substrate to between 40° and 65° (such as 40°, 45°, 50°, 55°, 60° or 65°).

[0039] Preferably, the drying temperature is 50°C to 150°C (such as 50°C, 55°C, 60°C, 65°C, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C), and the thickness of the dried primer coating layer is 200 nm to 800 nm (such as 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 600 nm, 700 nm or 800 nm).

[0040] Preferably, the surface treatment can also be to treat the PMMA surface with a solution containing a silane coupling agent.

[0041] Preferably, the silane coupling agent is γ-aminopropyltriethoxysilane.

[0042] In the present invention, one end of the silane coupling agent molecule can chemically react with the functional groups (such as ester groups) on the PMMA surface, and the other end can interact with certain functional groups in the polyurethane, thereby enhancing the binding force between the polyurethane and the PMMA.

[0043] Preferably, the coating method is selected from any one of wire bar coating, extrusion coating or microgravure coating. Wire bar coating means that there are circular linear protrusions on the surface of the coating roller. When the coating roller passes through the liquid tank below, the coating liquid can be temporarily stored between the linear protrusions. When the coating roller rolls and contacts the PMMA substrate above, the coating liquid is coated on the surface of the PMMA substrate; Extrusion coating means using a T-shaped extrusion orifice, and when the PMMA substrate passes by, the liquid can be evenly coated on the surface of the PMMA substrate; Microgravure coating means that there are small grooves on the surface of the coating roller. When the coating roller passes through the liquid tank, the coating liquid can be temporarily stored in the grooves and coated on the surface of the PMMA substrate when it contacts the PMMA substrate.

[0044] On the other hand, the present invention provides a polarizer, which uses the PMMA film as described above as a protective layer, for example, as a protective layer for PVA.

[0045] Compared with the prior art, the present invention has the following beneficial effects:

[0046] By combining the aqueous polyurethane resin with the hydrophobic polyurethane resin, the present invention endows the base film with more excellent water resistance and chemical stability, thereby effectively extending the service life of the base film and improving its overall durability and reliability; The coating liquid exhibits excellent dispersion, which helps to improve the transmittance of the base film and makes the light transmission more efficient. BRIEF DESCRIPTION OF THE DRAWINGS

[0047] Figure 1 It is a cross-sectional scanning electron microscope picture of the PMMA film of the present invention;

[0048] Figure 2 Schematic structural diagram of the PMMA film of the present invention;

[0049] Figure 3 Schematic structural diagram of the polarizer of the present invention;

[0050] In the figure: 1. Upper protective film layer; 2. Upper adhesive layer; 3. Polarizer sub-film layer; 4. Lower adhesive layer; 5. Lower protective film layer. Specific embodiments

[0051] The technical solution of the present invention will be further described below through specific embodiments. Those skilled in the art should understand that the embodiments are only for helping to understand the present invention and should not be regarded as specific limitations on the present invention.

[0052] Example 1

[0053] This example provides a primer coating solution and a preparation method thereof. The primer coating solution comprises the following components in parts by weight: 2 parts of aqueous polyurethane resin, 1 part of hydrophobic polyurethane resin, 2 parts of crosslinking agent, 0.5 part of compatibilizer, 0.1 part of dispersant, 1 part of silica particles, and 100 parts of pure water; wherein: the aqueous polyurethane resin (Bayhydrol UH2606 of Covestro) is copolymerized by reacting 5-amino-1,3,3-trimethyl-cyclohexylmethylamine with Α-hydro-Ω-hydroxy-poly(oxy-1,4-butylene) and 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane, the hydrophobic polyurethane resin is polysiloxane-modified polyurethane (PUR 50E of Wacker), the compatibilizer is maleic anhydride-grafted polyolefin (Polybond 3200 of Polybond), the dispersant is Solsperse 41000 (Lubrizol), and the crosslinking agent is oxazoline (Epocros WS-700 of NipponShokubai).

[0054] The preparation method of the primer coating solution is as follows:

[0055] S1. Add silica particles, pure water, and dispersant into the reaction vessel in sequence according to a preset ratio, and stir at a speed of 200 rpm for 40 min to obtain a first mixed solution;

[0056] S2. Add the aqueous polyurethane resin and the compatibilizer to the first mixed solution according to a preset ratio, and stir at a speed of 200 rpm for 60 min to obtain a second mixed solution;

[0057] S3. Add hydrophobic polyurethane resin to the second mixed solution at a preset ratio, and stir for 70 min at a rotation speed of 300 rpm to obtain a third mixed solution;

[0058] S4. Add a crosslinking agent to the third mixed solution at a preset ratio, stir for 40 min at a rotation speed of 100 rpm, and after stirring evenly, circulate and filter for 60 min in a filter with a filter element pore size of 1 μm. After circulation filtration, let it stand for 3 h in a low-pressure environment of -0.1 Mpa to 0 Mpa until the bubbles completely disappear to obtain the primer coating solution. Among them: the pure water is the pure water with a resistivity of 12 MΩ·cm after being irradiated by 250 nm ultraviolet light.

[0059] This embodiment also provides a PMMA film, which includes a PMMA substrate and a primer coating solution layer provided on the surface of the PMMA substrate, and the primer coating solution layer is prepared from the primer coating solution prepared in this embodiment. Among them: the PMMA film is prepared by the following method: First, corona-treat the surface of the PMMA substrate with a power of 1 KW to reduce the contact angle of the surface of the PMMA substrate to less than 65°; Second, evenly coat a layer of primer coating solution layer on the surface of the PMMA substrate and dry it at a temperature of 80 °C to obtain the PMMA film. Among them, the thickness of the primer coating solution layer after drying is 330 nm.

[0060] Example 2

[0061] This embodiment provides a primer coating solution and a preparation method thereof. The primer coating solution includes the following components in parts by weight: 6 parts of waterborne polyurethane resin, 5 parts of hydrophobic polyurethane resin, 8 parts of crosslinking agent, 2 parts of compatibilizer, 0.5 part of dispersant, 6 parts of silica particles, and 120 parts of pure water; Among them: the waterborne polyurethane resin (Bayhydrol UH2606 of Covestro) is copolymerized from 5-amino-1,3,3-trimethyl-cyclohexylmethylamine, Α-hydro-Ω-hydroxy-poly(oxy-1,4-butylene) and 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane, the hydrophobic polyurethane resin is polysiloxane-modified polyurethane (PUR 50E of Wacker), the compatibilizer is maleic anhydride-grafted polyolefin (Polybond 3200 of Polybond), the crosslinking agent is oxazoline (Epocros WS-700 of Nippon Shokubai), and the dispersant is Solsperse 41000 (Lubrizol).

[0062] The preparation method of the primer coating solution is specifically as follows:

[0063] S1. Add silica particles, pure water, and a dispersant into the reaction vessel in sequence according to a preset ratio, and stir for 20 min at a rotation speed of 500 rpm to obtain a first mixed solution;

[0064] S2. Add an aqueous polyurethane resin and a compatibilizer into the first mixed solution according to a preset ratio, and stir for 20 min at a rotation speed of 500 rpm to obtain a second mixed solution;

[0065] S3. Add a hydrophobic polyurethane resin into the second mixed solution according to a preset ratio, and stir for 30 min at a rotation speed of 600 rpm to obtain a third mixed solution;

[0066] S4. Add a crosslinking agent into the third mixed solution according to a preset ratio, stir for 20 min at a rotation speed of 500 rpm. After stirring evenly, circulate and filter for 20 min in a filter with a filter element pore size of 10 μm, and then let it stand for 6 h in a low-pressure environment of -0.1 Mpa to 0 Mpa until the bubbles completely disappear to obtain a primer coating solution. Among them: the pure water is pure water with a resistivity of 18 MΩ·cm after being irradiated by 250-nm ultraviolet light.

[0067] This embodiment also provides a PMMA film, including a PMMA substrate and a primer coating solution layer provided on the surface of the PMMA substrate, and the primer coating solution layer is prepared from the primer coating solution prepared in this embodiment. Among them: the PMMA film is prepared by the following method: First, corona-treat the surface of the PMMA substrate with a power of 6 KW to reduce the contact angle of the surface of the PMMA substrate to less than 65°; Second, evenly coat a layer of primer coating solution layer on the surface of the PMMA substrate and dry it at 80°C to obtain a PMMA film, where the thickness of the primer coating solution layer after drying is 400 nm.

[0068] Example 3

[0069] This embodiment provides a primer coating solution and a preparation method thereof. The primer coating solution comprises the following components in parts by weight: 4 parts of polyurethane resin, 1 part of hydrophobic polyurethane resin, 3 parts of crosslinking agent, 1 part of compatibilizer, 0.3 part of dispersant, 2 parts of silica particles, and 110 parts of pure water; wherein: the polyurethane resin (Bayhydrol UH 2606 of Covestro) is copolymerized from 5-amino-1,3,3-trimethyl-cyclohexylmethylamine, Α-hydro-Ω-hydroxy-poly(oxy-1,4-butylene), and 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane. The hydrophobic polyurethane resin is polysiloxane-modified polyurethane (PUR 50E of Wacker), the compatibilizer is maleic anhydride-grafted polyolefin (Polybond3200 of Polybond), the crosslinking agent is oxazoline (Epocros WS-700 of Nippon Shokubai), and the dispersant is Solsperse41000 (Lubrizol).

[0070] The preparation method of the primer coating solution is as follows:

[0071] S1. Add silica particles, pure water, and dispersant into the reaction vessel in sequence according to a preset ratio, and stir at a speed of 350 rpm for 30 min to obtain a first mixed solution;

[0072] S2. Add aqueous polyurethane resin and compatibilizer to the first mixed solution according to a preset ratio, and stir at a speed of 350 rpm for 40 min to obtain a second mixed solution;

[0073] S3. Add hydrophobic polyurethane resin to the second mixed solution according to a preset ratio, and stir at a speed of 450 rpm for 50 min to obtain a third mixed solution;

[0074] S4. Add a crosslinking agent to the third mixed solution according to a preset ratio, stir at a speed of 300 rpm for 30 min, and after stirring evenly, circulate and filter in a filter with a filter element pore size of 5 μm for 40 min. After circulation filtration, let it stand in a low-pressure environment of -0.1 Mpa to 0 Mpa for 4.5 h until the bubbles completely disappear to obtain the primer coating solution.

[0075] Wherein: the pure water is pure water with a resistivity of 15 MΩ·cm after being irradiated by 250 nm ultraviolet light.

[0076] This embodiment also provides a PMMA film, and its cross-sectional scanning electron microscope picture is as Figure 1 shown, and its cross-sectional structure schematic diagram is as Figure 2As shown in the figure, it includes a PMMA substrate and a primer coating liquid layer provided on the surface of the PMMA substrate. The primer coating liquid layer is prepared from the primer coating liquid prepared in this embodiment. Among them: The PMMA film is prepared by the following method: First, the surface of the PMMA substrate is treated by corona with a power of 1KW to reduce the contact angle of the surface of the PMMA substrate to less than 65°; Second, a layer of primer coating liquid layer is evenly coated on the surface of the PMMA substrate and dried at 80°C to obtain a PMMA film. Among them, the thickness of the primer coating liquid layer after drying is 330nm.

[0077] Comparative Example 1

[0078] The difference between this comparative example and Example 3 is that in the components of the primer coating liquid, hydrophobic polyurethane resin is not used, compatibilizer is not used, and the weight portion of the waterborne polyurethane resin is adjusted to 5 parts.

[0079] Comparative Example 2

[0080] The difference between this comparative example and Example 3 is that silica particles are not added to the components of the primer coating liquid.

[0081] Comparative Example 3

[0082] The difference between this comparative example and Example 3 is that a layer of primer coating liquid layer is directly and evenly coated on the surface of the PMMA substrate without corona treatment.

[0083] Comparative Example 4

[0084] Use the PMMA substrate as a comparative sample.

[0085] Comparative Example 5

[0086] The difference between this comparative example and Example 3 is that the hydrophobic polyurethane resin in the components of the primer coating liquid is replaced with acrylate resin (HA-100 of Wanhua Chemical HA-100)

[0087] To verify that the technical solution of this application has excellent technical effects, the PMMA films prepared in the above Examples 1-3 and Comparative Examples 1-4 are subjected to performance tests.

[0088] Moisture permeability: Add 30g ± 0.1g (m0) desiccant into the moisture permeation cup, cover the mouth of the cup with an optical film with an area of S, S = the area of the cup mouth, and then put the moisture permeation cup sealed with the PMMA film into a constant temperature and humidity machine at 60°C and 90%, take it out after placing it for 24H, confirm the weight of the desiccant m, and the moisture permeability = (m - m0) / S; The moisture permeability not higher than 140g / m 2 / day is judged as qualified, and a lower value is preferred.

[0089] Transmittance: The sample was placed in a visible spectrophotometer VAP-8010 manufactured by JASCO for measurement. A transmittance value of 90% or more was determined to be qualified, and a higher value was preferred.

[0090] Peeling force: The PMMA film was made into Figure 3 the polarizer shown in the figure. Test pieces with a size of 15 cm * 15 mm (the long side is the extending direction of PVA) were cut, and the peeling force between PMMA and PVA was measured using a tensile machine. A value of 128 gf / 15 mm or more was determined to be qualified, and a higher value was preferred.

[0091] For the upper and lower protective layers of PVA in the polarizer, the PMMA film of the present application was used, and the primer surface of the PMMA film was adhered to PVA through an adhesive.

[0092] Weather resistance optical change: The polarizer prepared as above was placed in a constant temperature and humidity machine at 60 °C and 90%. The transmittance at 0 hr and 500 hr was measured, and the change amount of the transmittance was calculated. A value not higher than 3% was qualified, and a lower value was preferred.

[0093] The performance test data are shown in Table 1.

[0094] Table 1: Performance test data corresponding to Examples 1-3 and Comparative Examples 1-4

[0095]

[0096]

[0097] In Table 1, NG indicates unqualified.

[0098] From the test results of the transmittance and peeling force of Examples 1-3 and Comparative Examples 1-4, it can be seen that the coating liquid designed in the present application adds hydrophobic polyurethane to the resin and can improve the transmittance of the PMMA film by controlling the ratio of waterborne polyurethane and hydrophobic polyurethane in the main resin. After being adhered to the UV adhesive layer, the adhesion ability is improved.

[0099] Comparing Example 3 with Comparative Example 1, after adding hydrophobic polyurethane resin to the main resin compared with using traditional single waterborne polyurethane resin components in the main resin, the water resistance of the PMMA film is improved. The same hydrophobic polarizer of PMMA film + polarizer + PMMA film is used, and the adhesion to the UV adhesive layer and the weather resistance of the polarizer are improved;

[0100] Comparing Example 3 with Comparative Example 2, after adding silica particles, the adhesion between the PMMA films is prevented.

[0101] Comparing Example 3 with Comparative Example 3, after the PMMA substrate is subjected to corona treatment, the adhesion to the UV adhesive layer is improved.

[0102] Comparing Example 3 with Comparative Example 4, after a primer layer is coated on the surface of the PMMA substrate, the adhesion between PMMA and the UV adhesive layer is improved, and adhesion between PMMA films is prevented.

[0103] Comparing Example 3 with Comparative Example 5, when the hydrophobic polyurethane resin is replaced with an acrylate resin, the moisture permeability is improved, and the hydrophobic polyurethane resin is more beneficial to the water resistance of the film than the acrylate resin.

[0104] In summary, in the coating liquid formulation designed in this application, the main resin is a mixture of a waterborne polyurethane resin and a hydrophobic polyurethane resin. This mixed resin has good film-forming properties and hydrophobicity, can effectively improve the water resistance of the PMMA film, maintain or even improve the adhesion between the PMMA film and the PVA film, prevent the polarizer from delaminating, and improve the weather resistance of the polarizer.

[0105] The applicant declares that the present invention uses the above embodiments to illustrate the primer coating liquid, PMMA film, and their preparation methods and applications of the present invention. However, 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 to the present invention, equivalent replacement of the raw materials selected for 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 primer coating solution, characterized in that: The primer coating solution includes the following components in parts by weight:

2. The primer coating liquid according to claim 1, characterized in that The waterborne polyurethane resin is a polymer having a hydroxyl group or a tertiary amine group formed by the reaction of polyester polyol and isocyanate; Further preferably, the waterborne polyurethane resin is formed by copolymerization of 5-amino-1,3,3-trimethyl-cyclohexylmethylamine with Α-hydrogen-Ω-hydroxy-poly(oxy-1,4-butylene) and 5-isocyanato-1-(isocyanatomethyl)-1,3,3-trimethylcyclohexane.

3. The primer coating liquid according to claim 1 or 2, characterized in that: The hydrophobic polyurethane resin is one or a combination of at least two of fluorine-containing polyurethane, silicone-modified polyurethane, aliphatic isocyanate-based polyurethane, long-chain alkyl-modified polyurethane or polysiloxane-modified polyurethane, and polysiloxane-modified polyurethane is more preferred.

4. The primer coating solution according to any one of claims 1 to 3, characterized in that: The cross-linking agent is selected from one or a combination of at least two of oxazoline, acrylamide or carbodiimide; Preferably, the compatibilizer is one or a combination of at least two of a maleic anhydride grafted polymer, a polyolefin copolymer, an aminosilane coupling agent, a polyester-polyether polyol block copolymer or a hydrophobic polyurethane-polyurethane block copolymer; Preferably, the dispersant is one or a combination of at least two of an acrylate dispersant, a high molecular weight block copolymer dispersant or a polyether-modified polysiloxane dispersant.

5. The primer coating solution according to any one of claims 1 to 4, characterized in that: The particle size of the silicon dioxide particles is 30 to 100 nm; Preferably, the water is water that has been sterilized by ultraviolet light at 180 to 254 nm; Preferably, the resistivity of the water is 12-18 MΩ·cm.

6. The method for preparing a primer coating solution according to any one of claims 1 to 5, characterized in that: The preparation method comprises the following steps: S1, mixing silica particles, water, and a dispersant to obtain a first mixed solution; S2, adding an aqueous polyurethane resin and a compatibilizer to the first mixed solution, and mixing to obtain a second mixed solution; S3, adding a hydrophobic polyurethane resin to the second mixed solution, and mixing to obtain a third mixed solution; S4, adding a crosslinking agent to the third mixed solution, mixing, and filtering to obtain the primer coating solution.

7. The preparation method according to claim 6, characterized in that: The mixing in step S1 is achieved by the following operations: stirring at a speed of 200 rpm to 500 rpm for 20 min to 40 min; Preferably, the mixing in step S2 is achieved by the following operations: stirring at a speed of 200 rpm to 500 rpm for 20 min to 60 min; Preferably, the mixing in step S3 is achieved by the following operations: stirring at a speed of 300 rpm to 600 rpm for 30 min to 70 min; Preferably, the mixing in step S4 is achieved by the following operations: stirring at a speed of 100 rpm to 500 rpm for 20 min to 40 min; Preferably, the filtration in step S4 is performed by circulating filtration for 20 to 60 minutes using a filter with a filter element pore size of 1 μm to 10 μm; Preferably, after the filtration in step S4, the mixture is allowed to stand in a low pressure environment of -0.1 MPa to 0 MPa for 3 to 6 hours until the bubbles completely disappear, thereby obtaining the primer coating solution.

8. A PMMA film, characterized in that: The PMMA film comprises a PMMA substrate and a primer coating liquid layer disposed on the surface of the PMMA substrate, wherein the primer coating liquid layer is prepared from the primer coating liquid according to any one of claims 1 to 5.

9. The method for preparing a PMMA film according to claim 8, characterized in that: The preparation method comprises the following steps: Evenly coating the primer coating liquid on the surface of the PMMA substrate, and drying it to obtain a PMMA film; Preferably, the PMMA substrate is surface treated before applying the primer coating liquid; Preferably, the surface treatment is to use a corona treatment with a power of 0.1KW to 6KW to treat the surface of the PMMA substrate, so that the contact angle of the surface of the PMMA substrate is reduced to between 40° and 65°; Preferably, the drying temperature is 50°C to 150°C, and the thickness of the primer coating liquid layer after drying is 200nm to 800nm; Preferably, the surface treatment may also be treating the PMMA surface with a solution containing a silane coupling agent; Preferably, the silane coupling agent is γ-aminopropyltriethoxysilane; Preferably, the coating method is selected from any one of wire rod coating, extrusion coating or micro-concave coating.

10. A polarizer, characterized in that: The polarizer uses the PMMA film as claimed in claim 8 as a protective layer.

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