Optical multilayer (METH)acrylic resin film and polarization film

Abstract

To provide an optical multilayer (meth)acrylic resin film which can achieve a low haze, and a polarization film.SOLUTION: An optical multilayer (meth)acrylic resin film 10 has a plurality of (meth)acrylic resin layers 11 and 12, wherein thickness of a first (meth)acrylic resin layer 11 containing a first (meth)acrylic polymer, rubber particles and a first crosslinking agent is 1 to 20 μm, thickness of a second (meth)acrylic resin layer 12 which contains a second (meth)acrylic polymer and a second crosslinking agent and does not contain rubber particles is 0.5 to 2.0 μm, film thickness of the plurality of (meth)acrylic resin layers 11 and 12 is 1.5 μm to 22 μm, a total haze value of the plurality of (meth)acrylic resin layers 11 and 12 is 1.0% or less, and an external haze value of an external contact surface 14 with which the second (meth)acrylic resin layer 12 is brought into contact in the outside is 0.4% or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] Conventionally, (meth)acrylic resin films have been used as resin films for surface coating of various equipment parts such as electronic devices, home appliances, automobile interior / exterior parts, and building materials due to their excellent transparency, heat processability, weather resistance, and chemical resistance (see, for example, Patent Document 1). In addition, (meth)acrylic resin films have been used as optical films due to their excellent transparency, weather resistance, and the like (see, for example, Patent Document 2). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2009-298122 [Patent Document 2] Japanese Patent Application Laid-Open No. 2012-180422 Summary of the Invention [Problem to be solved by the invention]

[0004] Low haze is required for optical film applications, particularly for displays.

[0005] 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 that can achieve low haze. [Means for solving the problem]

[0006] A first aspect is an optical multilayer (meth)acrylic resin film having a plurality of (meth)acrylic resin layers, the film comprising: a first (meth)acrylic resin layer containing a first (meth)acrylic polymer, rubber particles, and a first crosslinking agent; and a second (meth)acrylic resin layer laminated on the first (meth)acrylic resin layer, the second (meth)acrylic resin layer containing a second (meth)acrylic polymer and a second crosslinking agent but not containing rubber particles; the first (meth)acrylic resin layer has a thickness of 1 to 20 μm, the second (meth)acrylic resin layer has a thickness of 0.5 to 2.0 μm, the laminate comprising the plurality of (meth)acrylic resin layers has a film thickness of 1.5 μm to 22 μm, the laminate comprising the plurality of (meth)acrylic resin layers has a total haze value of 1.0% or less, and the external haze value of the surface of the second (meth)acrylic resin layer that contacts the outside is 0.4% or less.

[0007] The second aspect is the first aspect, which has 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.

[0008] A third aspect is a (meth)acrylic polymer according to the first or second aspect, wherein the first (meth)acrylic polymer is a (meth)acrylic polymer comprising a copolymer having a weight average molecular weight of more than 100,000 and not more than 1,000,000, obtained by copolymerizing (1A) a first alkyl (meth)acrylate, the copolymer comprising 80 parts by weight or more of methyl methacrylate and 100 parts by weight of at least one alkyl (meth)acrylate other than the methyl methacrylate, the homopolymer of which has a Tg of 0°C or higher and the alkyl group has carbon atoms of C1 to C14, and (1B) a first copolymerizable monomer, the copolymer comprising 1.0 to 20.0 parts by weight of at least one copolymerizable monomer having a functional group capable of reacting with the first crosslinking agent, the weight average molecular weight being more than 100,000 and not more than 1,000,000, and the rubber particles are contained in a ratio of 1.0 to 25.0 parts by weight per 100 parts by weight of the (1A) first alkyl (meth)acrylate.

[0009] A fourth aspect is a (meth)acrylic polymer according to any one of the first to third aspects, wherein the second (meth)acrylic polymer is a copolymer having a weight-average molecular weight of more than 50,000 and not more than 500,000, obtained by copolymerizing (2A) a second alkyl (meth)acrylate, which is 100 parts by weight in total of 80 parts by weight or more of methyl methacrylate and at least one alkyl (meth)acrylate, other than the methyl methacrylate, whose alkyl group has a carbon number of C1 to C14; and (2B) a second copolymerizable monomer, which is 1.0 to 30.0 parts by weight in total of at least one copolymerizable monomer having a functional group capable of reacting with the second crosslinking agent.

[0010] In a fifth aspect, in any one of the first to fourth aspects, the rubber particles are core-shell particles formed of a rubber layer mainly made of SBR or butadiene in the core portion and an acrylic layer mainly made of methyl methacrylate in the shell portion, and the volume-based average particle diameter of the rubber particles is 0.05 to 2.0 μm.

[0011] A sixth aspect is any one of the first to fifth aspects, wherein the first (meth)acrylic polymer and / or the second (meth)acrylic polymer is at least one selected from the group of compounds 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 also contains at least one selected from the group of compounds consisting of 8-hydroxyoctyl methacrylate, 6-hydroxyhexyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxyethyl acrylate.

[0012] A seventh aspect is any one of the first to sixth aspects, wherein the laminate formed by combining the plurality of (meth)acrylic resin layers has an in-plane retardation Re of 1.0 nm or less.

[0013] The eighth aspect is a polarizing film obtained from the optical multilayer (meth)acrylic resin film of any one of the first to seventh aspects, in which a laminate of the multiple (meth)acrylic resin layers is formed on one or both sides of a polarizer. [Effects of the Invention]

[0014] According to the present invention, there are provided an optical multilayer (meth)acrylic resin film and a polarizing film that can achieve low haze. [Brief explanation of the drawings]

[0015] [Figure 1] FIG. 1 is a cross-sectional view showing a first example of an optical multilayer (meth)acrylic resin film. [Figure 2] FIG. 2 is a cross-sectional view showing a second example of an optical multilayer (meth)acrylic resin film. [Figure 3] FIG. 1 is a cross-sectional view illustrating an example of a polarizing film. DETAILED DESCRIPTION OF THE INVENTION

[0016] The present invention will be described below based on preferred embodiments.

[0017] 1 and 2 show a first example and a second example of an optical multilayer (meth)acrylic resin film, respectively, and Fig. 3 shows an example of a polarizing film.

[0018] The optical multilayer (meth)acrylic resin film 10 of the first example has 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 suitably used as at least one of the protective layers 31 and 32 of the polarizer 33 in the polarizing film 30.

[0019] The optical multilayer (meth)acrylic resin film 20 of the second example has a support 15 and a plurality of (meth)acrylic resin layers 11, 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 has been peeled off is a laminate comprising a plurality of (meth)acrylic resin layers 11, 12.

[0020] The first (meth)acrylic resin layer 11 contains a first (meth)acrylic polymer, rubber particles, and a first crosslinking agent. The second (meth)acrylic resin layer 12 contains a second (meth)acrylic polymer and a second crosslinking agent, but does not contain rubber particles.

[0021] The first (meth)acrylic resin layer 11 has a thickness of 1 to 20 μm, the second (meth)acrylic resin layer 12 has a thickness of 0.5 to 2.0 μm, and the total thickness of the multiple (meth)acrylic resin layers 11, 12 is 1.5 μm to 22 μm.

[0022] The total haze value of the multiple (meth)acrylic resin layers 11, 12 combined is 1.0% or less. The lower the haze value, the less light is scattered when passing through the optical multilayer (meth)acrylic resin film 10, and therefore light leakage due to scattered light can be suppressed.

[0023] The external haze value of the external contact surface 14 where the second (meth)acrylic resin layer 12 contacts the outside is 0.4% or less. The external haze value is the difference between the total haze value measured when the external contact surface 14, which is one side of the optical multilayer (meth)acrylic resin film 10, is in contact with the outside (air) and the internal haze value measured when neither side of the optical multilayer (meth)acrylic resin film 10 is in contact with the outside (air). When the external haze value is low, the haze value is low even when the external contact surface 14 is in contact with the outside (air), which makes it easier to inspect and measure the optical properties.

[0024] 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 rubber particles contained in the first (meth)acrylic resin layer 11 is restricted by the support 15, whereas undulations, irregularities, etc. due to the rubber particles may occur at the interface between the (meth)acrylic resin layers 11 and 12. According to the above-mentioned configuration, the external contact surface 14 is formed in the second (meth)acrylic resin layer 12, which does not contain rubber particles, and therefore external haze at the external contact surface 14 can be reduced.

[0025] The first crosslinking agent may be a compound having a crosslinkable functional group capable of undergoing a crosslinking reaction with the functional group of the first (meth)acrylic polymer. The second crosslinking agent may be a compound having a crosslinkable functional group capable of undergoing a crosslinking reaction with the functional group of the second (meth)acrylic polymer. The functional group capable of reacting with these crosslinking agents may be a hydroxyl group or a carboxyl group.

[0026] The first (meth)acrylic polymer may be a copolymer having a weight average molecular weight of more than 100,000 and not more than 1,000,000, obtained by copolymerizing (1A) a first alkyl (meth)acrylate, which is 100 parts by weight of a total of 80 parts by weight or more of methyl methacrylate and at least one alkyl (meth)acrylate other than the methyl methacrylate, whose homopolymer has a Tg of 0°C or higher and whose alkyl group has carbon atoms of C1 to C14, and (1B) a first copolymerizable monomer, which is 1.0 to 20.0 parts by weight of a total of at least one copolymerizable monomer having a functional group capable of reacting with the first crosslinking agent.

[0027] The first (meth)acrylic resin layer 11 preferably contains 1.0 to 25.0 parts by weight of rubber particles per 100 parts by weight of the (1A) first alkyl (meth)acrylate in total. The rubber particles are not particularly limited, but core-shell particles formed of a core rubber layer mainly made of styrene-butadiene rubber (SBR) or butadiene and a shell acrylic layer mainly made of methyl methacrylate are preferred. The volume-based average particle diameter of the rubber particles is preferably 0.05 to 2.0 μm.

[0028] The second (meth)acrylic polymer may be a copolymer having a weight average molecular weight of more than 50,000 and not more than 500,000, obtained by copolymerizing (2A) a second alkyl (meth)acrylate, which is 100 parts by weight in total of 80 parts by weight or more of methyl methacrylate and at least one alkyl (meth)acrylate, other than the methyl methacrylate, whose alkyl group has a carbon number of C1 to C14, and (2B) a second copolymerizable monomer, which is 1.0 to 30.0 parts by weight in total of at least one copolymerizable monomer having a functional group that can react with the second crosslinking agent.

[0029] The rubber particles are in a particulate form. The first (meth)acrylic resin layer 11 contains rubber particles, which can improve flex resistance. The rubber particles may be particles of a rubber compound made of a vinyl polymer such as an olefin elastomer, a styrene elastomer, an acrylic elastomer, an acrylic rubber, a nitrile rubber, a butadiene rubber, a polyisoprene rubber, or a natural rubber. The rubber compound may be crosslinked by physical or chemical crosslinking.

[0030] The volume-based average particle size of the rubber particles is preferably 0.05 to 2.0 μm, more preferably 0.05 to 1.0 μm, and even more preferably 0.1 to 0.3 μm. The particle size of the core-shell particles includes the range of the shell portion. The ratio of the rubber particles to 100 parts by weight of the (1A) first alkyl (meth)acrylate is preferably 1.0 to 25.0 parts by weight, more preferably 3.0 to 20.0 parts by weight.

[0031] The (meth)acrylic resin composition may contain, without particular limitation, known additives such as antioxidants, surfactants, crosslinking accelerators, crosslinking retarders, curing accelerators, curing retarders, plasticizers, fillers, lubricants, processing aids, antioxidants, 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.

[0032] The first and / or second (meth)acrylic polymer may be a copolymer containing, as a main component, a (meth)acrylate such as an alkyl (meth)acrylate, where (meth)acrylate means at least one of acrylate and methacrylate.

[0033] The alkyl group of the alkyl (meth)acrylate may be either acyclic (straight-chain or branched) or cyclic (monocyclic or polycyclic). In the following description, when the Tg of a monomer is simply referred to, it may refer to the Tg of the homopolymer.

[0034] The proportion of methyl methacrylate in 100 parts by weight of (1A) first alkyl(meth)acrylate is preferably 80 to 99 parts by weight. The alkyl(meth)acrylate used in (1A) first alkyl(meth)acrylate, other than methyl methacrylate, in which the number of carbon atoms in the alkyl group is C1 to C14, has a Tg of 0°C or higher.

[0035] The proportion of methyl methacrylate in 100 parts by weight of (2A) second alkyl (meth)acrylate is preferably 80 to 99 parts by weight. The alkyl (meth)acrylate used in (2A) second alkyl (meth)acrylate, in which the alkyl group has a carbon number of C1 to C14 other than methyl methacrylate, may have a Tg of 0°C or higher or lower than 0°C.

[0036] In (1A) and / or (2A), the alkyl(meth)acrylate in which the Tg of the homopolymer is 0°C or higher and the alkyl group has a carbon number of C1 to C14 may be at least one selected from the group consisting of methyl(meth)acrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, s-butyl methacrylate, t-butyl(meth)acrylate, n-pentyl methacrylate, isopentyl methacrylate, n-hexyl methacrylate, isohexyl methacrylate, cyclohexyl(meth)acrylate, isobornyl(meth)acrylate, and dicyclopentanyl(meth)acrylate.

[0037] In (1A) and / or (2A), the number of carbon atoms in the alkyl group in the alkyl (meth)acrylate having a homopolymer Tg of 0° C. or higher is preferably C1 to C6, and more preferably C1 to C4. Specific examples include one or more selected from the group consisting of methyl acrylate, ethyl methacrylate, n-propyl methacrylate, isopropyl methacrylate, n-butyl methacrylate, isobutyl methacrylate, s-butyl methacrylate, t-butyl acrylate, and t-butyl methacrylate.

[0038] In (2A), the number of carbon atoms in the alkyl group in the alkyl (meth)acrylate having a Tg of less than 0° C. is preferably C1 to C6, and more preferably C1 to C4. Specific examples include ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate, isobutyl acrylate, s-butyl acrylate, n-pentyl acrylate, isopentyl acrylate, n-hexyl acrylate, and isohexyl acrylate.

[0039] The (1B) first copolymerizable monomer 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 ratio of the (1B) first copolymerizable monomer to 100 parts by weight of the (1A) first alkyl (meth)acrylate 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.

[0040] The (2B) second copolymerizable monomer 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 ratio of the (2B) second copolymerizable monomer to 100 parts by weight of the (2A) second alkyl (meth)acrylate is preferably 1.0 to 30.0 parts by weight.

[0041] In (1B) and / or (2B), the copolymerizable monomer having a hydroxyl group is preferably a hydroxyalkyl(meth)acrylate, a hydroxyl group-containing (meth)acrylamide, etc. Specifically, at least one 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 is preferred.

[0042] In addition, in (1B) and / or (2B), it is preferable that the copolymerizable monomer having a hydroxyl group includes at least one selected from the group consisting of 8-hydroxyoctyl methacrylate, 6-hydroxyhexyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxyethyl acrylate.

[0043] In (1B) and / or (2B), the copolymerizable monomer having a carboxyl group is preferably at least one selected from the group consisting of (meth)acrylic acid, carboxyethyl (meth)acrylate, carboxypentyl (meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, 2-(meth)acryloyloxypropyl hexahydrophthalic acid, 2-(meth)acryloyloxyethyl phthalic acid, 2-(meth)acryloyloxyethyl succinic acid, 2-(meth)acryloyloxyethyl maleic acid, carboxypolycaprolactone mono(meth)acrylate, 2-(meth)acryloyloxyethyl tetrahydrophthalic acid, and the like.

[0044] The methods for producing the first and second (meth)acrylic polymers are not particularly limited, and any known polymerization method can be used as appropriate, such as solution polymerization, emulsion polymerization, etc. (1B) may be any polymer as long as it is copolymerizable with (1A), and (2B) may be any polymer as long as it is copolymerizable with (2A).

[0045] The weight-average molecular weight of the first (meth)acrylic polymer is preferably more than 100,000 and not more than 1,000,000, more preferably more than 100,000 and not more than 950,000, and particularly preferably more than 100,000 and not more than 900,000. The weight-average molecular weight of the second (meth)acrylic polymer is preferably a copolymer of more than 50,000 and not more than 500,000. If the weight-average molecular weight is below the lower limit, it becomes difficult to obtain a (meth)acrylic resin film having excellent physical properties even after crosslinking. If the weight-average molecular weight exceeds the upper limit, the polymer solution becomes highly viscous, resulting in poor workability.

[0046] Specific examples of the first crosslinking agent and the second crosslinking agent are preferably one or more compounds 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 may be the same compound or different compounds.

[0047] Examples of epoxy crosslinking agents made of epoxy compounds include bifunctional or higher epoxy compounds. Examples of aziridine crosslinking agents made of aziridine compounds include bifunctional or higher aziridine compounds. Examples of isocyanate crosslinking agents made of isocyanate compounds include bifunctional isocyanates (diisocyanate compounds) and trifunctional or higher polyisocyanate compounds such as biuret-modified isocyanates, isocyanurate-modified isocyanates, and adducts thereof.

[0048] Examples of the diisocyanate compound include hexamethylene diisocyanate (HDI), isophorone diisocyanate (IPDI), diphenylmethane diisocyanate (MDI), tolylene diisocyanate (TDI), xylylene diisocyanate (XDI), etc. Examples of the adduct include adducts of a diisocyanate compound with a trivalent or higher polyol such as trimethylolpropane or glycerin.

[0049] The amount of the first crosslinking agent is not particularly limited, but may be, for example, 0.01 to 10 parts by weight per 100 parts by weight of the total of (1A) the first alkyl (meth)acrylate. The amount of the second crosslinking agent is not particularly limited, but may be, for example, 0.01 to 10 parts by weight per 100 parts by weight of the total of (2A) the second alkyl (meth)acrylate.

[0050] The optical multilayer (meth)acrylic resin film 20 of the second example can be produced by coating a first (meth)acrylic resin layer 11 and a second (meth)acrylic resin layer 12 in this order on a support 15. The optical multilayer (meth)acrylic resin film 10 of the first example can be produced by peeling off the support 15 from the optical multilayer (meth)acrylic resin film 20 of the second example.

[0051] 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, while 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 no rubber particles.

[0052] The coating method is not particularly limited, but for example, a solution of the (meth)acrylic resin composition can be applied to a predetermined support by a solution casting method to form a thin film, and then the thin film can be dried by heating to volatilize the solvent from the thin film. Examples of the support include resin films such as polyester and polyolefin films, and release films.

[0053] The gel fraction of the (meth)acrylic resin layers 11 and 12 is preferably 50% or more, more preferably 70% or more, even more preferably 90 to 100%, and particularly preferably 93 to 100%. When the (meth)acrylic resin composition is crosslinked and the gel fraction increases, the solvent resistance of the (meth)acrylic resin layers 11 and 12 can be improved.

[0054] The in-plane retardation Re of the optical multilayer (meth)acrylic resin film 10, which is a laminate of a plurality of (meth)acrylic resin layers 11, 12, is preferably 1.0 nm or less. The smaller the in-plane retardation Re, the more optically isotropic the (meth)acrylic resin film becomes, and the more effectively color tone change can be suppressed when the (meth)acrylic resin film is attached to an optical device or used for optical inspection.

[0055] One or more layers, such as a hard coat layer, an antistatic layer, an antireflection layer, an antifouling layer, an antiglare layer, a low refractive index layer, an adhesive layer, and a release layer, may be laminated on one or both sides of the optical multilayer (meth)acrylic resin film 10, 20. When these layers are laminated, they are preferably disposed on at least one of the support contact surface 13 or the external contact surface 14. The multiple (meth)acrylic resin layers 11, 12 preferably contact each other at their interface without any intervening layer. The multiple (meth)acrylic resin layers 11, 12 may be composed of only two layers, a first (meth)acrylic resin layer 11 and a second (meth)acrylic resin layer 12. Examples of fluorine compounds used in the composition for forming the low refractive index layer include fluorine-containing copolymers, which are polymers of one or more of fluorinated olefins, fluorinated vinyl ethers, and fluorinated alkyl (meth)acrylates, and condensates of fluorinated alkyl group-containing silane compounds.

[0056] The optical multilayer (meth)acrylic resin films 10, 20 can be suitably used for optical applications. Examples of optical applications include optical films in various display devices such as liquid crystal displays, touch panels, electronic paper, and organic EL displays. An example of an optical film is a polarizing film.

[0057] 3 is formed by forming protective layers 31 and 32 on both sides of a polarizer 33. Examples of materials for 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 polycarbonates. By using an 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.

[0058] The surface treatment applied to the surfaces of the protective layers 31 and 32 of the polarizer 33 may be at least one selected from the group consisting of untreated, AG treatment, LR treatment, AR treatment, AG-LR treatment, and AG-AR treatment, where AG stands for anti-glare, LR stands for low reflection, and AR stands for anti-reflection.

[0059] While the present invention has been described above based on preferred embodiments, the present invention is not limited to the above-described embodiments and various modifications are possible without departing from the spirit of the present invention. Modifications include addition, substitution, omission, and other changes to components in each embodiment. [Example]

[0060] The present invention will be specifically described below with reference to examples.

[0061] <Production of First (Meth)acrylic Polymer Solution> [Resin A] Nitrogen gas was introduced into a reactor equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube, and the air inside the reactor was replaced with nitrogen gas. Then, 90 parts by weight of methyl methacrylate, 10 parts by weight of methyl acrylate, 6.0 parts by weight of 2-hydroxyethyl methacrylate, and a solvent (ethyl acetate) were added to the reactor. Then, 0.1 parts by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise, 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 this (meth)acrylic polymer solution was measured and found to be 450,000.

[0062] [Resin B~C] (Meth)acrylic polymer solutions of Resins B to C were obtained in the same manner as for Resin A, except that the compositions of the (meth)acrylic polymers of Resin A were each as shown in Table 1. The weight average molecular weights (Mw) of Resins B to C are as shown in the "First polymer solution" column in Table 1.

[0063] <Production of second (meth)acrylic polymer solution> [Resin D] Nitrogen gas was introduced into a reactor equipped with a stirrer, thermometer, reflux condenser, and nitrogen inlet tube, and the air inside the reactor was replaced with nitrogen gas. Subsequently, 95 parts by weight of methyl methacrylate, 5 parts by weight of n-butyl acrylate, 10.0 parts by weight of 4-hydroxybutyl acrylate, and a solvent (ethyl acetate) were added to the reactor. Then, 0.1 parts by weight of azobisisobutyronitrile as a polymerization initiator was added dropwise, 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 this (meth)acrylic polymer solution was measured and found to be 250,000.

[0064] [Resin E~F] (Meth)acrylic polymer solutions of Resins E to F were obtained in the same manner as for Resin D, except that the compositions of the (meth)acrylic polymers of Resin D were each as shown in Table 1. The weight average molecular weights (Mw) of Resins E to F are as shown in the "Second Polymer Solution" column in Table 1.

[0065] [Table 1]

[0066] In Table 1, each symbol represents the following material. The numbers in brackets indicate the blend amount (parts by weight).

[0067] Monomers of Groups (1A) and (2A) MMA: Methyl methacrylate MA: methyl acrylate BMA: n-butyl methacrylate BA: n-butyl acrylate EA: Ethyl acrylate

[0068] Monomers of Groups (1B) and (2B) HEMA: 2-hydroxyethyl methacrylate 6HHMA: 6-hydroxyhexyl methacrylate 8HOMA: 8-hydroxyoctyl methacrylate 4HBA: 4-hydroxybutyl acrylate HEA: 2-hydroxyethyl acrylate

[0069] <Preparation of optical multilayer (meth)acrylic resin film> [Example 1] To the (meth)acrylic polymer solution of 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 resulting (meth)acrylic polymer solution, 4.5 parts by weight of Coronate (registered trademark) HX (an isocyanurate of a hexamethylene diisocyanate compound) as a crosslinking agent and 0.01 parts by weight of dioctyltin dilaurate were added and stirred, yielding a first (meth)acrylic resin composition. The resulting resin composition was applied to a release film to form a film, and then heated and dried under temperature conditions suitable for drying the solvent and curing the crosslinking agent, followed by crosslinking, to form a first (meth)acrylic resin layer of Example 1 on the support. The thickness (μm) of the resulting first (meth)acrylic resin layer is shown in Table 2 under "Thickness" in the "First Resin Layer" column.

[0070] Next, 4.0 parts by weight of Duranate (registered trademark) TPA-100 was added as a crosslinking agent to the (meth)acrylic polymer solution of 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 side of the first (meth)acrylic resin layer opposite the side in contact with the release film, and then heated and dried under temperature conditions suitable for drying the solvent and curing the crosslinking agent, followed by crosslinking, to obtain the optical multilayer (meth)acrylic resin film of Example 1. The thickness (μm) of the obtained second (meth)acrylic resin layer is shown in Table 2 under "Thickness" in the "Second Resin Layer" column.

[0071] [Examples 2 to 6] The optical multilayer (meth)acrylic resin films described in Examples 2 to 6 were obtained in the same manner as in Example 1, except that the compositions of the first and second (meth)acrylic resin compositions and the thicknesses of the (meth)acrylic resin layers were each set as shown in Table 2.

[0072] <Preparation of (meth)acrylic resin films of comparative examples and reference examples> [Comparative Examples 1 to 4] The comparative examples did not have a second (meth)acrylic resin layer, and the (meth)acrylic resin films described in Comparative Examples 1 to 4 were obtained in the same manner as in Example 1, except that the composition of the first (meth)acrylic resin composition and the thickness of the (meth)acrylic resin layer were each as shown in Table 2.

[0073] [Reference example] To the (meth)acrylic polymer solution of Resin A, 1.0 parts by weight of acetylacetone, 4.5 parts by weight of Coronate (registered trademark) HX (an isocyanurate of a hexamethylene diisocyanate compound) as a crosslinker, and 0.01 parts by weight of dioctyltin dilaurate were added and stirred and mixed, and the mixture was applied to a release film to form a film, which was then heated and dried at temperatures suitable for drying the solvent and curing the crosslinker, and crosslinked to obtain a (meth)acrylic resin film of the reference example. The thickness (μm) of the obtained (meth)acrylic resin film of the reference example is shown in Table 2 under "Thickness" in the "First Resin Layer" column.

[0074] [Table 2]

[0075] In Table 2, each symbol represents the following material. The numbers in brackets indicate the blend amount (parts by weight).

[0076] Rubber Group M210: Kane Ace (registered trademark) M-210 (core-shell particles, particle diameter: 0.2 μm, core: SBR, shell: MMA, product name of Kaneka Corporation) M230: Kane Ace (registered trademark) M-230 (core-shell particles, particle diameter: 0.1 μm, core: SBR, shell: MMA, product name of Kaneka Corporation)

[0077] (X) group AAc: acetylacetone (Y) group DOTL: Dioctyl tin dilaurate

[0078] Crosslinking agent group HX: Coronate (registered trademark) HX (HDI isocyanurate, trade name of Tosoh Corporation) HL: Coronate (registered trademark) HL (HDI adduct, trade name of Tosoh Corporation) TPA: Duranate (registered trademark) TPA-100 (HDI isocyanurate, trade name of Asahi Kasei Corporation) TKA: Duranate (registered trademark) TKA-100 (HDI isocyanurate, trade name of Asahi Kasei Corporation)

[0079] <Optical properties of (meth)acrylic resin films> The optical properties of the (meth)acrylic resin films (hereinafter also referred to as "test films") obtained by peeling the support (release film) from the (meth)acrylic resin films of Examples 1 to 6, Comparative Examples 1 to 4, and Reference Example were measured as follows.

[0080] (1) Total haze value, total light transmittance (Tt) Test pieces were prepared from the test films, and the total haze value and total light transmittance (Tt) were measured using a haze meter (manufacturer: Murakami Color Research Institute Co., Ltd., model: Haze Meter HM-150N) in accordance with JIS K 7136 (2000).

[0081] (2) Internal haze value As a blank, two test pieces of 50 μm thick COP film (ZEONOR ZF-16, Zeon Corporation) with a 10 μm thick adhesive sheet (specifically, an optical transparent acrylic adhesive sheet) attached were prepared, and the two test pieces were attached so that the adhesive sheet surfaces were attached 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 this was taken as the haze value H of the two blank pieces. b2 (%).

[0082] Next, a test piece was prepared from the test film, and the blank was attached to the side that had been in close contact with the support and the side opposite the support (the air side). The haze value (%) of the resulting "COP film / adhesive sheet / test film / adhesive sheet / COP film" laminate was measured using the haze meter in accordance with JIS K 7136 (2000), and this was designated as the haze value H1 of the test film having blanks on both sides.

[0083] The internal haze value (%) of the test film was calculated using the following formula. Internal haze value (%) = H1 (%) - H b2 (%)

[0084] (3) External haze value A test piece was prepared from the test film, and the blank was attached to the side that had been in close contact with the support. The haze value (%) of the resulting "COP film / adhesive sheet / test film" laminate was measured using the haze meter in accordance with JIS K 7136 (2000), and this was designated as the haze value H2 of the test film having the blank on one side.

[0085] The external haze value (%) of the test film was calculated using the following formula. External haze value (%) = H2 (%) - (H b2 (%)÷2)-Internal haze value (%)

[0086] (4) Measurement results Table 3 shows the measurement results of the optical properties of the (meth)acrylic resin film.

[0087] [Table 3]

[0088] 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. 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 high external haze values. The (meth)acrylic resin film of Reference Example 1 had low total haze and internal haze values, and not only high total light transmittance but also a low external haze value, but was poor in flex resistance because it did not contain rubber particles. [Explanation of symbols]

[0089] 10, 20... optical multilayer (meth)acrylic resin film, 11... first (meth)acrylic resin layer, 12... second (meth)acrylic resin layer, 13... support contact surface, 14... external contact surface, 15... support, 30... polarizing film, 31, 32... protective layer, 33... polarizer.

Claims

1. An optical multilayer (meth)acrylic resin film having a plurality of (meth)acrylic resin layers, a first (meth)acrylic resin layer containing a first (meth)acrylic polymer, rubber particles, and a first crosslinking agent; a second (meth)acrylic resin layer laminated on the first (meth)acrylic resin layer, the second (meth)acrylic resin layer containing a second (meth)acrylic polymer and a second crosslinking agent, and not containing rubber particles; The first (meth)acrylic resin layer has a thickness of 1 to 20 μm, The thickness of the second (meth)acrylic resin layer is 0.5 to 2.0 μm, the thickness of the laminate including the plurality of (meth)acrylic resin layers is 1.5 μm to 22 μm; the total haze value of the laminate including the plurality of (meth)acrylic resin layers is 1.0% or less; An optical multilayer (meth)acrylic resin film, wherein 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. 2. The optical multilayer (meth)acrylic resin film according to claim 1, comprising: 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 first (meth)acrylic polymer is (1A) a first alkyl (meth)acrylate, comprising 80 parts by weight or more of methyl methacrylate and 100 parts by weight of at least one alkyl (meth)acrylate other than the methyl methacrylate, the homopolymer of which has a Tg of 0° C. or more and the alkyl group has a carbon number of C1 to C14; (1B) a first copolymerizable monomer, the total amount of which is 1.0 to 20.0 parts by weight of at least one copolymerizable monomer having a functional group capable of reacting with the first crosslinking agent; and having a weight average molecular weight of more than 100,000 and not more than 1,000,000, The optical multilayer (meth)acrylic resin film according to claim 1 or 2, characterized in that the rubber particles are contained in a ratio of 1.0 to 25.0 parts by weight per 100 parts by weight of the (1A) first alkyl (meth)acrylate.

4. The second (meth)acrylic polymer is (2A) a second alkyl (meth)acrylate, comprising 80 parts by weight or more of methyl methacrylate and 100 parts by weight of at least one alkyl (meth)acrylate other than the methyl methacrylate, the alkyl group of which has a carbon number of C1 to C14; (2B) a second copolymerizable monomer, the second copolymerizable monomer being 1.0 to 30.0 parts by weight in total of at least one copolymerizable monomer having a functional group capable of reacting with the second crosslinking agent; 3. The optical multilayer (meth)acrylic resin film according to claim 1, wherein the (meth)acrylic polymer is a copolymer having a weight average molecular weight of more than 50,000 and not more than 500,000, obtained by copolymerizing

5. 3. The optical multilayer (meth)acrylic resin film according to claim 1, wherein the rubber particles are core-shell particles having a core portion made of a rubber layer mainly made of SBR or butadiene and a shell portion made of an acrylic layer mainly made of methyl methacrylate, and the rubber particles have a volume-based average particle diameter of 0.05 to 2.0 μm.

6. 3. The optical multilayer (meth)acrylic resin film according to claim 1, wherein the first (meth)acrylic polymer and / or the second (meth)acrylic polymer is at least one selected from the group of compounds 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 further contains at least one selected from the group of compounds consisting of 8-hydroxyoctyl methacrylate, 6-hydroxyhexyl methacrylate, 4-hydroxybutyl methacrylate, 2-hydroxyethyl methacrylate, and 2-hydroxyethyl acrylate.

7. 3. The optical multilayer (meth)acrylic resin film according to claim 1, wherein the laminate of the plurality of (meth)acrylic resin layers has an in-plane retardation Re of 1.0 nm or less.

8. 3. A polarizing film comprising a laminate of a plurality of (meth)acrylic resin layers obtained from the optical multilayer (meth)acrylic resin film according to claim 1 or 2, formed on one or both sides of a polarizer.

Images