Multilayer (meth) acrylic resin film for optical use and polarizing film

Abstract

The present invention provides an optical multilayer (meth) acrylic resin film and a polarizing film capable of achieving low haze. The optical multilayer (meth) acrylic resin film has a plurality of (meth) acrylic resin layers including a first (meth) acrylic resin layer and a second (meth) acrylic resin layer, and is characterized in that: the thickness of the first (meth) acrylic resin layer containing a first (meth) acrylic polymer, rubber particles, and a first crosslinking agent is 1-20 [mu] m; the thickness of a second (meth) acrylic resin layer containing a second (meth) acrylic polymer and a second crosslinking agent and not containing rubber particles is 0.5-2.0 [mu] m, the film thickness after a plurality of (meth) acrylic resin layers are laminated is 1.5-22 [mu] m, and the total haze value after a plurality of (meth) acrylic resin layers are laminated is 1.0% or less. The external haze value of the surface of the second (meth) acrylic resin layer in contact with the outside is 0.4% or less.

Description

Technical Field

[0001] The present invention relates to an optical multilayer (meth) acrylic resin film and a polarizing film. Background Art

[0002] Conventionally, (meth)acrylic resin films have been used as resin films for covering the surfaces of various equipment parts such as electronic devices, home appliances, automobile interior and exterior parts, and building components from the viewpoints of high transparency, heat processability, weather resistance, and excellent chemical resistance (for example, see Patent Document 1). In addition, (meth)acrylic resin films have been used as optical films due to their excellent properties such as high transparency and weather resistance (for example, see Patent Document 2).

[0003] Patent Document 1: Japanese Patent Application Publication No. 2009-298122

[0004] Patent Document 2: Japanese Patent Application Publication No. 2012-180422 Summary of the invention

[0005] Low haze is required for the use of optical films, particularly for use in displays.

[0006] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an optical multilayer (meth)acrylic resin film and a polarizing film capable of achieving low haze.

[0007] A first embodiment is an optical multilayer (meth)acrylic resin film, comprising a plurality of (meth)acrylic resin layers, the plurality of (meth)acrylic resin layers comprising: a first (meth)acrylic resin layer comprising a first (meth)acrylic polymer, rubber particles and a first crosslinking agent; and a second (meth)acrylic resin layer comprising a second (meth)acrylic polymer and a second crosslinking agent laminated on the first (meth)acrylic resin layer and not containing rubber particles, the first (meth)acrylic resin layer having a thickness of 1 μm to 20 μm, the second (meth)acrylic resin layer having a thickness of 0.5 μm to 2.0 μm, the film thickness of a laminate formed by laminating the plurality of (meth)acrylic resin layers having a thickness of 1.5 μm to 22 μm, the total haze value of the laminate formed by laminating the plurality of (meth)acrylic resin layers being 1.0% or less, and the external haze value of a surface of the second (meth)acrylic resin layer in contact with the outside being 0.4% or less.

[0008] A second embodiment is an optical multilayer (meth)acrylic resin film according to the first embodiment, comprising a support and the plurality of (meth)acrylic resin layers formed by sequentially coating the first (meth)acrylic resin layer and the second (meth)acrylic resin layer on the support.

[0009] A third embodiment is an optical multilayer (meth)acrylic resin film according to the first embodiment or the second embodiment, wherein the first (meth)acrylic polymer is a (meth)acrylic polymer composed of a copolymer having a weight average molecular weight of more than 100,000 and less than 1,000,000 formed by copolymerizing (1A) a first (meth)acrylic acid alkyl ester and (1B) a first copolymerizable monomer, wherein in the (1A) first (meth)acrylic acid alkyl ester, 80 parts by weight or more of methyl methacrylate and at least one (meth)acrylic acid alkyl ester other than the methyl methacrylate whose homopolymer has a Tg of 0° C. or more and an alkyl group having carbon atoms of C1 to C14 are present in a total of 100 parts by weight, in the (1B) first copolymerizable monomer, at least one copolymerizable monomer having a functional group capable of reacting with the first crosslinking agent is present in a total of 1.0 to 20.0 parts by weight, and the content of the rubber particles is 1.0 to 25.0 parts by weight relative to a total of 100 parts by weight of the (1A) first (meth)acrylic acid alkyl ester.

[0010] A fourth embodiment is an optical multilayer (meth)acrylic resin film according to any one of the first to third embodiments, wherein the second (meth)acrylic polymer is a (meth)acrylic polymer composed of a copolymer having a weight average molecular weight of more than 50,000 and less than 500,000 formed by copolymerizing (2A) a second (meth)acrylic alkyl ester and (2B) a second copolymerizable monomer, wherein in the (2A) second (meth)acrylic alkyl ester, a total of more than 80 parts by weight of methyl methacrylate and at least one (meth)acrylic alkyl ester having an alkyl group with carbon atoms of C1 to C14 other than the methyl methacrylate is 100 parts by weight, and in the (2B) second copolymerizable monomer, a total of at least one copolymerizable monomer having a functional group capable of reacting with the second crosslinking agent is 1.0 to 30.0 parts by weight.

[0011] The fifth embodiment is: an optical multilayer (meth) acrylic resin film according to any one of the first to fourth embodiments, wherein the rubber particles are core-shell particles formed by a rubber layer with SBR or butadiene as a core and an acrylic layer with methyl methacrylate as a shell, and the volume-based average particle size of the rubber particles is 0.05 μm to 2.0 μm.

[0012] A sixth embodiment is: an optical multilayer (meth)acrylic resin film according to any one of the first to fifth embodiments, wherein the first (meth)acrylic polymer and / or the second (meth)acrylic polymer is one or more selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxyethyl (meth)acrylamide, and contains one or more selected from the group consisting of 8-hydroxyoctyl methacrylate, 6-hydroxyhexyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxyethyl acrylate.

[0013] A seventh aspect is the optical multilayer (meth)acrylic resin film according to any one of the first to sixth aspects, wherein the in-plane retardation Re of a laminate formed by laminating the plurality of (meth)acrylic resin layers is 1.0 nm or less.

[0014] The eighth embodiment is a polarizing film obtained from the optical multilayer (meth) acrylic resin film of any one of the first to seventh embodiments, wherein a laminated body formed by stacking the plurality of (meth) acrylic resin layers is formed on one or both sides of a polarizer.

[0015] According to the present invention, an optical multilayer (meth)acrylic resin film and a polarizing film capable of achieving low haze can be provided. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 This is a cross-sectional view showing a first example of the optical multilayer (meth)acrylic resin film.

[0017] Figure 2 This is a cross-sectional view showing a second example of the optical multilayer (meth)acrylic resin film.

[0018] Figure 3 It is a cross-sectional view showing an example of a polarizing film.

[0019] (Explanation of Reference Numerals)

[0020] 10, 20: Multilayer (meth) acrylic resin film for optical use

[0021] 11: First (meth) acrylic resin layer

[0022] 12: Second (meth) acrylic resin layer

[0023] 13: Support body close to the surface

[0024] 14: External contact surface

[0025] 15: Support body

[0026] 30: Polarizing film

[0027] 31, 32: Protective layer

[0028] 33: Polarizer DETAILED DESCRIPTION

[0029] Hereinafter, the present invention will be described based on preferred embodiments.

[0030] exist Figure 1 and Figure 2 The first and second examples of optical multilayer (meth) acrylic resin films are shown in FIG. Figure 3 An example of a polarizing film is shown in FIG.

[0031] The optical multilayer (meth)acrylic resin film 10 of the first example includes a plurality of (meth)acrylic resin layers 11 and 12. The second (meth)acrylic resin layer 12 is laminated on the first (meth)acrylic resin layer 11. The optical multilayer (meth)acrylic resin film 10 can be preferably used as at least one of the protective layers 31 and 32 of the polarizer 33 in the polarizing film 30.

[0032] The optical multilayer (meth)acrylic resin film 20 of the second example comprises a support 15 and a plurality of (meth)acrylic resin layers 11 and 12 formed by coating a first (meth)acrylic resin layer 11 and a second (meth)acrylic resin layer 12 in this order on the support 15. When the support 15 is peeled off from the optical multilayer (meth)acrylic resin film 20, the optical multilayer (meth)acrylic resin film 10 of the first example is obtained. The optical multilayer (meth)acrylic resin film 10 from which the support 15 is peeled off is a laminated body in which the plurality of (meth)acrylic resin layers 11 and 12 are stacked.

[0033] The first (meth)acrylic resin layer 11 contains a first (meth)acrylic polymer, rubber particles, and a first cross-linking agent.

[0034] The second (meth)acrylic resin layer 12 contains a second (meth)acrylic polymer and a second crosslinking agent, and does not contain rubber particles.

[0035] The thickness of the first (meth)acrylic resin layer 11 is 1 μm to 20 μm, the thickness of the second (meth)acrylic resin layer 12 is 0.5 μm to 2.0 μm, and the thickness of the laminated film of the plurality of (meth)acrylic resin layers 11 and 12 is 1.5 μm to 22 μm.

[0036] The total haze value after laminating the plurality of (meth)acrylic resin layers 11 and 12 is 1.0% or less. The lower the haze value, the less light scattering occurs when passing through the optical multilayer (meth)acrylic resin film 10, so that light leakage due to scattered light can be suppressed.

[0037] The external haze value of the external contact surface 14 of the second (meth) acrylic resin layer 12 in contact with the outside is 0.4% or less. The external haze value is the difference between the total haze value measured in a state where the external contact surface 14, which is one surface of the optical multilayer (meth) acrylic resin film 10, is in contact with the outside (air) and the internal haze value measured in a state where both surfaces of the optical multilayer (meth) acrylic resin film 10 are not in contact with the outside (Air). If the external haze value is low, the haze value is low even in a state where the external contact surface 14 is in contact with the outside (Air), so that inspection and measurement of optical properties become easy.

[0038] The optical multilayer (meth) acrylic resin film 10 of the first example has a support contact surface 13 where the first (meth) acrylic resin layer 11 is in close contact with the support 15. At the support contact surface 13, the movement of the rubber particles contained in the first (meth) acrylic resin layer 11 is restricted by the support 15, and on the other hand, undulations and irregularities caused by the rubber particles may occur at the boundary surface between the (meth) acrylic resin layers 11 and 12. According to the above-mentioned structure, the external contact surface 14 is formed on the second (meth) acrylic resin layer 12 that does not contain rubber particles, so the external haze value of the external contact surface 14 can be reduced.

[0039] Examples of the first crosslinking agent include compounds having a crosslinkable functional group capable of undergoing a crosslinking reaction with a functional group possessed by the first (meth)acrylic polymer. Examples of the second crosslinking agent include compounds having a crosslinkable functional group capable of undergoing a crosslinking reaction with a functional group possessed by the second (meth)acrylic polymer. Examples of the functional group capable of reacting with these crosslinking agents include hydroxyl groups and carboxyl groups.

[0040] The first (meth)acrylic polymer may be a copolymer having a weight average molecular weight of more than 100,000 and less than 1,000,000 obtained by copolymerizing (1A) a first (meth)acrylic acid alkyl ester and (1B) a first copolymerizable monomer, wherein the first (meth)acrylic acid alkyl ester (1A) comprises 80 parts by weight or more of methyl methacrylate and 100 parts by weight of one or more (meth)acrylic acid alkyl esters other than the methyl methacrylate whose homopolymer has a Tg of 0° C. or more and an alkyl group having carbon atoms of C1 to C14, and the first (meth)acrylic acid alkyl ester (1B) comprises 1.0 to 20.0 parts by weight of one or more copolymerizable monomers having a functional group capable of reacting with the first crosslinking agent.

[0041] Preferably, the first (meth) acrylic resin layer 11 contains 1.0 to 25.0 parts by weight of rubber particles relative to 100 parts by weight of the first (meth) acrylic acid alkyl ester (1A). The rubber particles are not particularly limited, but are preferably core-shell particles formed of a rubber layer containing styrene-butadiene rubber (SBR) or butadiene as a core and an acrylic layer containing methyl methacrylate as a shell. The volume-based average particle size of the rubber particles is preferably 0.05 μm to 2.0 μm.

[0042] The second (meth)acrylic polymer may be a copolymer having a weight average molecular weight of more than 50,000 and less than 500,000, which is obtained by copolymerizing (2A) a second (meth)acrylic acid alkyl ester and (2B) a second copolymerizable monomer, wherein the second (meth)acrylic acid alkyl ester (2A) comprises 80 parts by weight or more of methyl methacrylate and 100 parts by weight of at least one (meth)acrylic acid alkyl ester having an alkyl group with carbon atoms of C1 to C14 other than the methyl methacrylate, and the second copolymerizable monomer (2B) comprises 1.0 to 30.0 parts by weight of at least one copolymerizable monomer having a functional group capable of reacting with the second crosslinking agent.

[0043] The rubber particles are in particle form. The first (meth) acrylic resin layer 11 contains rubber particles, so that the bending resistance can be improved. As the rubber particles, particles of rubber compounds containing vinyl polymers such as olefin elastomers, styrene elastomers, acrylic elastomers, acrylic rubbers, nitrile rubbers, butadiene rubbers, polyisoprene rubbers, and natural rubbers can be used. The rubber compound can be cross-linked by physical cross-linking or chemical cross-linking.

[0044] The volume-based average particle size of the rubber particles is preferably 0.05 μm to 2.0 μm, more preferably 0.05 μm to 1.0 μm, and further preferably 0.1 μm to 0.3 μm. The particle size of the core-shell particles also includes the range of the shell portion. The content of the rubber particles is preferably 1.0 to 25.0 parts by weight, more preferably 3.0 to 20.0 parts by weight, relative to 100 parts by weight of the first (meth) alkyl ester (1A).

[0045] The (meth)acrylic resin composition is not particularly limited, and may be suitably formulated with known additives such as antioxidants, surfactants, crosslinking accelerators, crosslinking retarders, curing accelerators, curing retarders, plasticizers, fillers, lubricants, processing aids, anti-aging agents, heat stabilizers, light stabilizers, antistatic agents, colorants, ultraviolet absorbers, infrared absorbers, etc. These additives may be used alone or in combination of two or more.

[0046] Examples of the first (meth)acrylic polymer and / or the second (meth)acrylic polymer include copolymers containing (meth)acrylic acid esters such as (meth)acrylic acid alkyl esters as a main component. (Meth)acrylic acid esters refer to at least one of acrylic acid esters and methacrylic acid esters.

[0047] The alkyl group of the (meth)acrylic acid alkyl ester may be acyclic (linear, branched) or cyclic (monocyclic, polycyclic). In the following description, when Tg is simply mentioned for a monomer, it may refer to the Tg of a homopolymer.

[0048] The content of methyl methacrylate is preferably 80 to 99 parts by weight relative to 100 parts by weight of the first alkyl (meth)acrylate (1A). The alkyl (meth)acrylate other than methyl methacrylate used in the first alkyl (meth)acrylate (1A) and having an alkyl group with carbon atoms of C1 to C14 has a Tg of 0°C or higher.

[0049] The content of methyl methacrylate is preferably 80 to 99 parts by weight relative to 100 parts by weight of the second alkyl (meth)acrylate (2A). The alkyl (meth)acrylate other than methyl methacrylate used in the second alkyl (meth)acrylate (2A) having an alkyl group with carbon atoms of C1 to C14 may have a Tg of 0°C or higher, or may have a Tg of less than 0°C.

[0050] Examples of the alkyl (meth)acrylate in which the Tg of the homopolymer is 0° C. or higher and the number of carbon atoms of the alkyl group is C1 to C14 in the (1A) first alkyl (meth)acrylate and / or the (2A) second alkyl (meth)acrylate include at least one compound selected from the group consisting of methyl (meth)acrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, tert-butyl (meth)acrylate, n-pentyl methacrylate, isopentyl methacrylate, n-hexyl methacrylate, isohexyl methacrylate, cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, and dicyclopentanyl (meth)acrylate.

[0051] The carbon number of the alkyl group in the alkyl (meth)acrylate whose homopolymer Tg is 0° C. or higher in the (1A) first alkyl (meth)acrylate and / or the (2A) second alkyl (meth)acrylate is more preferably C1 to C6, and even more preferably C1 to C4. As a specific example, at least one selected from the group consisting of methyl acrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, sec-butyl methacrylate, t-butyl acrylate, and t-butyl methacrylate is particularly preferred.

[0052] The number of carbon atoms of the alkyl group in the alkyl (meth)acrylate having a Tg of less than 0° C. in the second alkyl (meth)acrylate (2A) is more preferably C1 to C6, and even more preferably C1 to C4. Specific examples include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, sec-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, and isohexyl acrylate.

[0053] The first copolymerizable monomer (1B) has a functional group capable of reacting with the first crosslinking agent. Examples of the functional group capable of reacting with the first crosslinking agent include a hydroxyl group and a carboxyl group. The content of the first copolymerizable monomer (1B) is preferably 1.0 to 20.0 parts by weight, more preferably 1.0 to 12.0 parts by weight, and particularly preferably 1.0 to 9.0 parts by weight, relative to 100 parts by weight of the first (meth)acrylate alkyl ester (1A).

[0054] The second copolymerizable monomer (2B) has a functional group capable of reacting with the second crosslinking agent. Examples of the functional group capable of reacting with the second crosslinking agent include a hydroxyl group and a carboxyl group. The content of the second copolymerizable monomer (2B) is preferably 1.0 to 30.0 parts by weight relative to 100 parts by weight of the second (meth) alkyl ester (2A).

[0055] The copolymerizable monomer having a hydroxyl group in (1B) the first copolymerizable monomer and / or (2B) the second copolymerizable monomer is preferably a hydroxyalkyl (meth)acrylate, a hydroxyl group-containing (meth)acrylamide, etc. Specifically, it is preferably one or more selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl(meth)acrylamide, and N-hydroxyethyl(meth)acrylamide.

[0056] In addition, in (1B) the first copolymerizable monomer and / or (2B) the second copolymerizable monomer, the copolymerizable monomer having a hydroxyl group is preferably one or more selected from the group consisting of 8-hydroxyoctyl methacrylate, 6-hydroxyhexyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxyethyl acrylate.

[0057] As the copolymerizable monomer having a carboxyl group in the (1B) first copolymerizable monomer and / or the (2B) second copolymerizable monomer, preferably one or more selected from the group consisting of (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalate, 2-(meth)acryloyloxypropyl hexahydrophthalate, 2-(meth)acryloyloxyethyl phthalate, 2-(meth)acryloyloxyethyl succinate, 2-(meth)acryloyloxyethyl maleate, carboxy polycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyl tetrahydrophthalate, and the like.

[0058] The production method of the first (meth)acrylic polymer and the second (meth)acrylic polymer is not particularly limited, and known polymerization methods such as solution polymerization and emulsion polymerization can be appropriately used. The first copolymerizable monomer (1B) can be any monomer as long as it is copolymerizable with the first (meth)acrylic alkyl ester (1A), and the second copolymerizable monomer (2B) can be any monomer as long as it is copolymerizable with the second (meth)acrylic alkyl ester (2A).

[0059] The weight average molecular weight of the first (meth) acrylic polymer is preferably more than 100,000 and less than 1,000,000, more preferably more than 100,000 and less than 950,000, and particularly preferably more than 100,000 and less than 900,000. The weight average molecular weight of the second (meth) acrylic polymer is preferably more than 50,000 and less than 500,000. If the weight average molecular weight is less than the lower limit, it is difficult to obtain a (meth) acrylic resin film having excellent physical properties even if cross-linking is performed. If the weight average molecular weight exceeds the upper limit, the polymer solution becomes highly viscous and the operability is poor.

[0060] Specific examples of the first crosslinking agent and the second crosslinking agent are preferably at least one selected from the group consisting of epoxy compounds, aziridine compounds, and isocyanate compounds. The first crosslinking agent and the second crosslinking agent can be independently selected and can be the same compound or different compounds.

[0061] As epoxy crosslinking agents composed of epoxy compounds, bifunctional or higher epoxy compounds can be cited. As aziridine crosslinking agents composed of aziridine compounds, bifunctional or higher aziridine compounds can be cited. As isocyanate crosslinking agents composed of isocyanate compounds, bifunctional isocyanates (diisocyanate compounds); trifunctional or higher polyisocyanate compounds such as their biuret modified products, isocyanurate modified products, and adducts can be cited.

[0062] Examples of the diisocyanate compound include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), toluene diisocyanate (TDI), xylylene diisocyanate (XDI), etc. Examples of the adduct include adducts of a diisocyanate compound and a trivalent or higher polyol such as trimethylolpropane and glycerol.

[0063] The content of the first crosslinking agent is not particularly limited, and may be, for example, 0.01 to 10 parts by weight relative to 100 parts by weight of the first (meth)acrylic acid alkyl ester (1A). The content of the second crosslinking agent is not particularly limited, and may be, for example, 0.01 to 10 parts by weight relative to 100 parts by weight of the second (meth)acrylic acid alkyl ester (2A).

[0064] The optical multilayer (meth)acrylic resin film 20 of the second example can be manufactured by sequentially coating the first (meth)acrylic resin layer 11 and the second (meth)acrylic resin layer 12 on the support 15. The optical multilayer (meth)acrylic resin film 10 of the first example can be manufactured by peeling the support 15 from the optical multilayer (meth)acrylic resin film 20 of the second example.

[0065] The first (meth)acrylic resin layer 11 can be formed by coating a first (meth)acrylic resin composition containing a first (meth)acrylic polymer, rubber particles, and a first crosslinking agent. The second (meth)acrylic resin layer 12 can be formed by coating a second (meth)acrylic resin composition containing a second (meth)acrylic polymer and a second crosslinking agent but not containing rubber particles.

[0066] The coating method is not particularly limited, and for example, a solution casting method can be used, in which a solution of a (meth)acrylic resin composition is coated on a predetermined support to form a thin film, and then the film is formed by heating and drying the film to volatilize the solvent from the thin film. Examples of the support include resin films such as polyester and polyolefin, and release films.

[0067] The gel fraction of the (meth)acrylic resin layers 11 and 12 is preferably 50% or more, more preferably 70% or more, further preferably 90% to 100%, and particularly preferably 93% to 100%. The gel fraction increases by crosslinking the (meth)acrylic resin composition, thereby improving the solvent resistance of the (meth)acrylic resin layers 11 and 12.

[0068] The in-plane phase difference Re of the optical multilayer (meth) acrylic resin film 10 formed by stacking a plurality of (meth) acrylic resin layers 11 and 12 is preferably 1.0 nm or less. The smaller the in-plane phase difference Re, the more optically isotropic the (meth) acrylic resin film is, and the more the change in color tone can be suppressed when the (meth) acrylic resin film is attached to an optical device or used for optical inspection.

[0069] On one or both sides of the optical multilayer (meth) acrylic resin film 10, 20, one or more of a hard coating layer, an antistatic layer, an antireflection layer, an antifouling layer, an antiglare layer, a low refractive index layer, an adhesive layer, a release layer, etc. can be laminated. In the case of laminating these layers, it is preferred to arrange them on at least one of the support body close contact surface 13 or the external contact surface 14. Preferably, the multiple (meth) acrylic resin layers 11, 12 are in contact with each other at the boundary surface without any other layer interposed between them. The multiple (meth) acrylic resin layers 11, 12 may be only two layers consisting of a first (meth) acrylic resin layer 11 and a second (meth) acrylic resin layer 12. As the fluorine compound used in the composition for forming the low refractive index layer, there can be listed: polymers of one or more of fluorinated olefins, fluorinated vinyl ethers, fluorinated alkyl (meth) acrylic acid esters, i.e., fluorinated copolymers; condensates of fluorinated alkyl-containing silane compounds, etc.

[0070] The optical multilayer (meth) acrylic resin films 10 and 20 can be suitably used for optical applications. Optical applications include optical films in various display devices such as liquid crystal display devices, touch panels, electronic paper, and organic EL. An example of an optical film is a polarizing film.

[0071] Figure 3 The polarizing film 30 shown is formed by forming protective layers 31 and 32 on both sides of a polarizer 33. Examples of the protective layers 31 and 32 of the polarizer 33 include acrylic resins such as triacetyl cellulose (TAC) and polymethyl methacrylate (PMMA), polyester resins such as polyethylene terephthalate (PET), cyclic olefin polymers, and polycarbonate. By using the optical multilayer (meth) acrylic resin film 10 for at least one of the protective layers 31 and 32, the total thickness of the polarizing film 30 can be reduced.

[0072] The surface treatment applied to the surface of the protective layers 31 and 32 of the polarizer 33 may be any one of untreated, AG treated, LR treated, AR treated, AG-LR treated, and AG-AR treated, or these treatments may be used in combination. Here, AG means anti-glare, LR means low reflection, and AR means anti-reflection.

[0073] The present invention has been described above based on preferred embodiments, but the present invention is not limited to the above embodiments and can be variously modified within the scope of the present invention. As a modification, addition, replacement, omission, and other changes of the constituent elements in each embodiment can be listed.

[0074] [Example]

[0075] Hereinafter, the present invention will be specifically described with reference to examples.

[0076] <Production of the first (meth)acrylic polymer solution>

[0077] [Resin A]

[0078] Nitrogen was introduced into a reaction device equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet pipe, and the air in the reaction device was replaced with nitrogen. Then, 90 parts by weight of methyl methacrylate, 10 parts by weight of methyl acrylate, and 6.0 parts by weight of 2-hydroxyethyl methacrylate were added to the reaction device, and a solvent (ethyl acetate) was added. Then, 0.1 parts by weight of azobisisobutyronitrile was added dropwise as a polymerization initiator, and the mixture was heated to 65° C. and reacted for a predetermined time to obtain a (meth) acrylic polymer solution of resin A. The weight average molecular weight (Mw) of the (meth) acrylic polymer contained in the (meth) acrylic polymer solution was measured and the result was 450,000.

[0079] [Resin B and Resin C]

[0080] A (meth)acrylic polymer solution of resin B and a (meth)acrylic polymer solution of resin C were obtained in the same manner as resin A, except that the composition of the (meth)acrylic polymer of resin A was as shown in Table 1. The weight average molecular weight (Mw) of resin B and resin C is shown in the "first polymer solution" column of Table 1.

[0081] <Production of Second (Meth)Acrylic Polymer Solution>

[0082] [Resin D]

[0083] Nitrogen was introduced into a reaction device equipped with a stirrer, a thermometer, a reflux condenser and a nitrogen inlet pipe, and the air in the reaction device was replaced with nitrogen. Then, 95 parts by weight of methyl methacrylate, 5 parts by weight of n-butyl acrylate, and 10.0 parts by weight of 4-hydroxybutyl acrylate were added to the reaction device, and a solvent (ethyl acetate) was added. Then, 0.1 parts by weight of azobisisobutyronitrile was added dropwise as a polymerization initiator, and the mixture was heated to 65° C. and reacted for a predetermined time to obtain a (meth) acrylic polymer solution of resin D. The weight average molecular weight (Mw) of the (meth) acrylic polymer contained in the (meth) acrylic polymer solution was measured and the result was 250,000.

[0084] [Resin E and Resin F]

[0085] A (meth)acrylic polymer solution of resin E and a (meth)acrylic polymer solution of resin F were obtained in the same manner as resin D, except that the composition of the (meth)acrylic polymer of resin D was as shown in Table 1. The weight average molecular weight (Mw) of resin E and resin F is shown in the "Second polymer solution" column of Table 1.

[0086]

Table 1

[0087]

[0088] In Table 1, each symbol refers to the following material. The numerical value in [ ] is the content (parts by weight).

[0089] Monomers of group (1A) and group (2A)

[0090] MMA: Methyl Methacrylate

[0091] MA: Methyl acrylate

[0092] BMA: n-butyl methacrylate

[0093] BA: n-butyl acrylate

[0094] EA: Ethyl acrylate

[0095] Monomers of group (1B) and group (2B)

[0096] HEMA: 2-Hydroxyethyl Methacrylate

[0097] 6HHMA: 6-Hydroxyhexyl methacrylate

[0098] 8HOMA: 8-Hydroxyoctyl Methacrylate

[0099] 4HBA: 4-Hydroxybutyl acrylate

[0100] HEA: 2-Hydroxyethyl Acrylate

[0101] <Production of optical multilayer (meth)acrylic resin film>

[0102] [Example 1]

[0103] To the (meth) acrylic polymer solution of the resin A, 10 parts by weight of KANE ACE (registered trademark) M-210 as rubber particles and 1.0 parts by weight of acetylacetone were added and stirred. To the obtained (meth) acrylic polymer solution, 4.5 parts by weight of Coronate (registered trademark) HX (isocyanurate of hexamethylene diisocyanate compound) as a crosslinking agent and 0.01 parts by weight of dioctyltin dilaurate were added and stirred and mixed to obtain a first (meth) acrylic resin composition. The obtained resin composition was applied on a release film to form a film, and the film was heated and dried and crosslinked under a temperature condition suitable for drying the solvent and curing the crosslinking agent to form the first (meth) acrylic resin layer of Example 1 on the support. The thickness (μm) of the obtained first (meth) acrylic resin layer is shown in the "Thickness" column of the "First Resin Layer" in Table 2.

[0104] Next, 3.0 parts by weight of Duranate (registered trademark) TPA-100 was added as a crosslinking agent to the (meth) acrylic polymer solution of the resin D, and the mixture was stirred and mixed to obtain a second (meth) acrylic resin composition. The obtained resin composition was applied to the surface opposite to the surface in contact with the release film of the first (meth) acrylic resin layer, and heated and dried and crosslinked under temperature conditions suitable for drying the solvent and curing the crosslinking agent to form a second (meth) acrylic resin layer, thereby obtaining an optical multilayer (meth) acrylic resin film of Example 1. The thickness (μm) of the obtained second (meth) acrylic resin layer is shown in the "Thickness" column of "Second Resin Layer" in Table 2.

[0105] [Examples 2 to 6]

[0106] Optical multilayer (meth)acrylic resin films of Examples 2 to 6 were obtained in the same manner as in Example 1 except that the compositions of the first (meth)acrylic resin composition and the second (meth)acrylic resin composition and the thickness of the (meth)acrylic resin layer were as shown in Table 2.

[0107] <Preparation of (meth)acrylic resin films of comparative examples and reference examples>

[0108] [Comparative Examples 1 to 4]

[0109] The (meth)acrylic resin films of Comparative Examples 1 to 4 were obtained in the same manner as in Example 1, except that the Comparative Examples did not have a second (meth)acrylic resin layer and the composition of the first (meth)acrylic resin composition and the thickness of the (meth)acrylic resin layer were as shown in Table 2.

[0110] [Reference example]

[0111] To the (meth)acrylic polymer solution of the resin A, 1.0 part by weight of acetylacetone, 4.5 parts by weight of Coronate (registered trademark) HX (isocyanurate of hexamethylene diisocyanate compound) as a crosslinking agent, and 0.01 part by weight of dioctyltin dilaurate were added, stirred and mixed, and the mixture was applied to a release film to form a film, and then heated and dried and crosslinked under temperature conditions suitable for drying the solvent and curing the crosslinking agent to obtain a (meth)acrylic resin film of a reference example. The thickness (μm) of the obtained (meth)acrylic resin film of the reference example is shown in the "Thickness" column of the "First Resin Layer" in Table 2.

[0112]

Table 2

[0113]

[0114] In Table 2, each symbol refers to the following material. The numerical value in [ ] is the content (parts by weight).

[0115] Rubber Group

[0116] M210: KANE ACE (registered trademark) M-210 (core-shell particles, particle size: 0.2 μm, core part: SBR, shell part: MMA, trade name of Kaneka Corporation)

[0117] M230: KANE ACE (registered trademark) M-230 (core-shell particles, particle size: 0.1 μm, core part: SBR, shell part: MMA, trade name of Kaneka Corporation)

[0118] (X) Group

[0119] AAc: acetylacetone

[0120] Group (Y)

[0121] DOTL: Dioctyltin dilaurate

[0122] Crosslinker group

[0123] HX: Coronate (registered trademark) HX (HDI isocyanurate, a trade name of Tosoh Corporation)

[0124] HL: Coronate (registered trademark) HL (HDI adduct, trade name of Tosoh Corporation)

[0125] TPA: Duranate (registered trademark) TPA-100 (HDI isocyanurate, trade name of Asahi Kasei Corporation)

[0126] TKA: Duranate (registered trademark) TKA-100 (HDI isocyanurate, trade name of Asahi Kasei Corporation)

[0127] <Optical properties of (meth)acrylic resin film>

[0128] The optical properties of the (meth)acrylic resin films (hereinafter also referred to as “test films”) obtained by peeling the support (peeling films) from the (meth)acrylic resin films of Examples 1 to 6, Comparative Examples 1 to 4 and Reference Example were measured as follows.

[0129] (1) Total haze value, total transmittance (Tt)

[0130] A test piece was prepared from the test film, and the total haze value and total light transmittance (Tt) were measured using a haze meter (manufacturer: Murakami Color Laboratory Co., Ltd., model: Haze Meter HM-150N) in accordance with JIS K 7136 (2000).

[0131] (2) Internal haze value

[0132] As a blank control, two test pieces of a 50 μm thick COP film (ZEONOR ZF-16, ZEON Corporation, Japan) bonded with a 10 μm thick adhesive sheet (specifically, an optical transparent acrylic adhesive sheet) were prepared, and the two test pieces were bonded so that the adhesive sheet surfaces were bonded to each other. The haze value (%) of the obtained "COP film / adhesive sheet / adhesive sheet / COP film" laminate was measured using the haze meter in accordance with JIS K 7136 (2000), and the haze value was taken as the haze value H of the two blank control pieces. b2 (%).

[0133] Next, a test piece was prepared from the test film, and the blank was attached to the surface in close contact with the support and the surface opposite to the support (air side). The haze value (%) of the obtained laminate of "COP film / adhesive sheet / test film / adhesive sheet / COP film" was measured using the haze meter in accordance with JIS K 7136 (2000), and the haze value was taken as the haze value H of the test film with the blank on both sides. 1 .

[0134] The internal haze value (%) of the test film was calculated according to the following formula.

[0135] Internal haze value (%) = H 1 (%) -H b2 (%)

[0136] (3) External haze value

[0137] A test piece was prepared from the test film, and the blank control was attached to the surface in close contact with the support. The obtained laminate of "COP film / adhesive sheet / test film" was used as the object, and the haze value (%) was measured using the haze meter in accordance with JIS K 7136 (2000), and the haze value was taken as the haze value H of the test film with the blank control on one side. 2 .

[0138] The external haze value (%) of the test film was calculated according to the following formula.

[0139] External haze value (%) = H 2 (%)-(H b2 (%)÷2)-Internal haze value (%)

[0140] (4) Measurement results

[0141] Table 3 shows the measurement results of the optical properties of the (meth)acrylic resin film.

[0142]

Table 3

[0143]

[0144] The optical multilayer (meth)acrylic resin films of Examples 1 to 6 not only had low total haze values ​​and internal haze values ​​and high total light transmittance, but also had low external haze values.

[0145] The (meth)acrylic resin films of Comparative Examples 1 to 4 had low total haze values ​​and internal haze values ​​and high total light transmittance, but had high external haze values.

[0146] The (meth)acrylic resin film of Reference Example 1 has low total haze value and internal haze value and high total light transmittance, and also has low external haze value. However, since it does not contain rubber particles, it has poor bending resistance.

Claims

1. An optical multilayer (meth) acrylic resin film having a plurality of (meth) acrylic resin layers, characterized in that: The plurality of (meth)acrylic resin layers include: A first (meth)acrylic resin layer comprising a first (meth)acrylic polymer, rubber particles and a first cross-linking agent; and The second (meth)acrylic resin layer contains a second (meth)acrylic polymer and a second crosslinking agent stacked on the first (meth)acrylic resin layer, and does not contain rubber particles. The thickness of the first (meth) acrylic resin layer is 1 μm to 20 μm. The thickness of the second (meth) acrylic resin layer is 0.5 μm to 2.0 μm. The thickness of the laminate formed by laminating the plurality of (meth)acrylic resin layers is 1.5 μm to 22 μm, The total haze value of the laminate formed by laminating the plurality of (meth)acrylic resin layers is 1.0% or less, The external haze value of the surface of the second (meth)acrylic resin layer in contact with the outside is 0.4% or less.

2. The optical multilayer (meth)acrylic resin film according to claim 1, wherein: The optical multilayer (meth)acrylic resin film includes a support and the plurality of (meth)acrylic resin layers formed by coating the first (meth)acrylic resin layer and the second (meth)acrylic resin layer in this order on the support.

3. The optical multilayer (meth) acrylic resin film according to claim 1 or 2, characterized in that: The first (meth)acrylic polymer is a (meth)acrylic polymer composed of a copolymer having a weight average molecular weight of more than 100,000 and less than 1,000,000, which is obtained by copolymerizing (1A) a first (meth)acrylic acid alkyl ester and (1B) a first copolymerizable monomer. In the first (meth)acrylic acid alkyl ester (1A), 80 parts by weight or more of methyl methacrylate and one or more (meth)acrylic acid alkyl esters other than the methyl methacrylate whose homopolymer Tg is 0° C. or higher and whose alkyl group has carbon atoms of C1 to C14 are added together to 100 parts by weight, In the (1B) first copolymerizable monomer, the total amount of one or more copolymerizable monomers having a functional group capable of reacting with the first crosslinking agent is 1.0 to 20.0 parts by weight, The content of the rubber particles is 1.0 to 25.0 parts by weight relative to 100 parts by weight of the total of the (1A) first alkyl (meth)acrylate.

4. The optical multilayer (meth)acrylic resin film according to claim 1 or 2, characterized in that: The second (meth)acrylic polymer is a (meth)acrylic polymer composed of a copolymer having a weight average molecular weight of more than 50,000 and less than 500,000, which is obtained by copolymerizing (2A) a second (meth)acrylic acid alkyl ester and (2B) a second copolymerizable monomer. In the second (meth)acrylic acid alkyl ester (2A), 80 parts by weight or more of methyl methacrylate and one or more (meth)acrylic acid alkyl esters other than the methyl methacrylate having an alkyl group with carbon atoms of C1 to C14 are added together to make 100 parts by weight, In the (2B) second copolymerizable monomer, the total amount of one or more copolymerizable monomers having a functional group capable of reacting with the second crosslinking agent is 1.0 to 30.0 parts by weight.

5. The optical multilayer (meth)acrylic resin film according to claim 1 or 2, characterized in that: The rubber particles are core-shell particles formed of a rubber layer mainly composed of SBR or butadiene as a core part and an acrylic layer mainly composed of methyl methacrylate as a shell part, and have a volume-based average particle size of 0.05 μm to 2.0 μm.

6. The optical multilayer (meth) acrylic resin film according to claim 1 or 2, characterized in that: The first (meth)acrylic polymer and / or the second (meth)acrylic polymer is one or more selected from the group consisting of 8-hydroxyoctyl (meth)acrylate, 6-hydroxyhexyl (meth)acrylate, 4-hydroxybutyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, N-hydroxy(meth)acrylamide, N-hydroxymethyl (meth)acrylamide, and N-hydroxyethyl (meth)acrylamide, and contains one or more selected from the group consisting of 8-hydroxyoctyl methacrylate, 6-hydroxyhexyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxyethyl acrylate.

7. The optical multilayer (meth)acrylic resin film according to claim 1 or 2, characterized in that: The in-plane phase difference Re of the laminated body formed by laminating the plurality of (meth)acrylic resin layers is 1.0 nm or less.

8. A polarizing film, characterized in that: The polarizing film is obtained from the optical multilayer (meth)acrylic resin film according to claim 1 or 2, wherein a laminated body formed by laminating the plurality of (meth)acrylic resin layers is formed on one or both surfaces of a polarizer.

Images