JP2016218478A - Acrylic resin film and polarizing plate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an acrylic resin film having high adhesive force with a polarizing film and less likely having problems caused by ruggedness upon forming a functional layer, a polarizing plate, and a production method of an acrylic resin film.SOLUTION: A sheet type acrylic resin film 25 comprises an acrylic resin composition in which rubber elastic particles are blended in an acrylic resin. One surface of the sheet is a smooth surface 25a, while an opposite surface to the smooth surface 25a is a rough surface 25b. On the rough surface 25b side, since the surface area of the rubber elastic particles protruding from the film surface is larger than the smooth surface 25a, high adhesion strength with a polarizing film 21 is obtained from an anchor effect caused by the ruggedness. On the smooth surface 25a side, since the surface area of the rubber elastic particles protruding from the film surface is smaller than the smooth surface 25a, a degree of ruggedness is low, which substantially prevents problems caused by a rugged pattern upon forming a functional layer 26.SELECTED DRAWING: Figure 1

Description

  TECHNICAL FIELD The present invention relates to an acrylic resin film, a polarizing plate using the same, and a method for producing an acrylic resin film, and in particular, an acrylic resin film containing rubber elastic particles, a polarizing plate using the acrylic resin film, and an acrylic resin film. It relates to the manufacturing method.

  The polarizing plate is used as a constituent member of a liquid crystal display device, and the demand for the polarizing plate is rapidly increasing with the spread of the liquid crystal display device. With the application of a liquid crystal display device to a large-sized television or the like, the polarizing plate is also required to be thinner and cheaper while maintaining or improving its performance.

  In general, a polarizing plate has a structure in which a transparent protective film is bonded to at least one side, usually both sides, of a polarizing film made of a polyvinyl alcohol-based resin in which a dichroic dye is adsorbed and oriented. As the protective film for the polarizing plate, a film of cellulose acetate resin typified by triacetyl cellulose is often used, and the thickness is usually about 40 to 120 μm. For bonding such a cellulose acetate resin film to a polarizing film, an adhesive made of an aqueous solution of a polyvinyl alcohol resin is often used. However, a polarizing plate in which a protective film is laminated on a polarizing film through a water-soluble adhesive has a problem that the polarizing performance is deteriorated or the protective film is peeled off from the polarizing film when used for a long time under wet heat conditions. was there.

  Therefore, there is an attempt to configure the protective film bonded to the polarizing film with a resin other than the cellulose acetate resin. As such a resin, a technique using an acrylic resin which is a relatively inexpensive resin material is known. As such a technique, for example, a protective film (see Patent Document 1) using a (meth) acrylic resin containing a lactone ring is known. Furthermore, a protective film (see Patent Document 2) is also developed in which an acrylic resin is uniaxially or biaxially stretched within a stretch ratio of 50 to 200%. By using such a stretched acrylic resin, an optical film having excellent mechanical strength and heat shrinkability can be obtained.

  However, the conventional outer resin film made of an acrylic resin has a problem that it is inferior in flexibility and easily broken. Therefore, research is being carried out to increase the flexibility of acrylic resin films and make them difficult to break. The inventors have so far developed a technique for increasing the flexibility of an acrylic resin film by blending rubber elastic particles with an acrylic resin.

JP 2009-122663 A JP 2008-216586 A

  By the way, generally a polarizing plate has a layer structure in which a protective film is bonded to the surface of a polarizing film with an adhesive. That is, the polarizing film is bonded to one surface of the protective film via the adhesive layer.

  The inventors have made researches on the acrylic resin film containing rubber elastic particles from various viewpoints. As a result, the acrylic resin film containing such rubber elastic particles has rubber elasticity on the surface. It was found that a part of the body had a protruding and recessed shape. And when the acrylic resin film in which such rubber elastic particles are blended is used as the protective film for the polarizing plate described above, there is a difference in the adhesive strength with the polarizing film due to the uneven shape of the surface of the acrylic resin film. It has been found that when a functional layer such as an antiglare layer is formed, problems such as deterioration in visibility occur due to the uneven shape on the surface of the acrylic resin film.

  However, a detailed study has not been made as to how the surface irregularities of the acrylic resin film can be made to have high adhesive force and good visibility.

  An object of the present invention is an acrylic resin film that has high adhesive force with another film such as a polarizing film on one surface side, and is less likely to cause problems due to unevenness when a functional layer is formed on the other surface. And a method of manufacturing the same. Another object of the present invention is to provide a polarizing plate that has good adhesion to a polarizing film and has few functional layer problems due to unevenness.

  As a result of diligent research, the inventors have made a difference in the concavo-convex shape on one side and the other side of the acrylic resin film, thereby forming an adhesive or functional layer with another film. Found that the impact of can be optimized. That is, when other films such as a polarizing film are bonded to the surface of an acrylic resin film via an adhesive layer, it is preferable that the surface has more irregularities, while an antiglare layer or the like is formed on the surface of the acrylic resin film. In the case of forming a functional layer, it has been found that it is preferable to have less irregularities because problems such as disturbance of the display image easily occur due to the irregular shape of the film surface, and the following invention has been completed.

  That is, the said subject is a sheet-like acrylic resin film which consists of an acrylic resin composition by which rubber elastic-body particle | grains were mix | blended with acrylic resin according to the acrylic resin film of this invention, Comprising: One surface is a smooth surface, and the surface of the sheet-like surface opposite to the smooth surface is a rough surface in which the surface area of the elastic rubber particles protruding from the film surface is larger than the smooth surface. It is solved by.

  In this case, the rubber elastic body particles preferably have a number average particle diameter in the range of 10 to 300 nm and are blended in an amount of 25 to 45% by weight with respect to the acrylic resin.

  The arithmetic average roughness difference between the rough surface and the smooth surface is preferably 5 to 100 nm.

  In addition, according to the polarizing plate of the present invention, the above-described problem is a polarizing plate comprising the acrylic resin film according to any one of the above and a polarizing film, and an adhesive layer is interposed on the rough surface. This is solved by laminating the polarizing film.

  In this case, the rough surface is preferably subjected to a surface activation treatment before the adhesive layer is laminated.

  The smooth surface preferably has a functional layer on the surface.

  According to the method for producing an acrylic resin film of the present invention, the subject is a method for producing an acrylic resin film according to any one of the above, and an extrusion step of melt-extruding the acrylic resin composition; A step of grounding the melt-extruded acrylic resin composition with a first roll and a second roll having a higher elastic modulus than the first roll to form a sheet, The surface of the resin-based resin film that contacts the first roll is the smooth surface, and the surface of the acrylic resin film that contacts the second roll is the rough surface.

  In this case, it is preferable that the first roll is a cooling roll.

  According to the acrylic resin film of the present invention, one surface of the sheet-like acrylic resin film is a smooth surface, and the other surface protrudes from the film surface, and the surface area of the rubber elastic particles is larger than the smooth surface. It is a rough surface. On the rough surface side, the surface area of the rubber elastic particles protruding from the film surface is larger than that of the smooth surface. Therefore, when another film such as a polarizing film is bonded to the rough surface side via an adhesive layer, the surface becomes uneven. The resulting anchor effect increases the adhesive strength and makes it difficult for the film to peel off. On the other hand, on the smooth surface side, since the surface area of the rubber elastic particles protruding from the film surface is smaller than that of the smooth surface, there is little unevenness, and this is caused by the uneven shape when forming a functional layer such as an antiglare layer. Problems are less likely to occur.

  In addition, according to the polarizing plate of the present invention, the polarizing film is bonded to the rough surface side of the acrylic resin film via the adhesive layer, and thus the adhesive force between the acrylic resin film and the polarizing film is high and easy. It is hard to peel off. Furthermore, when the functional layer is formed on the smooth surface side of the acrylic resin film, problems due to the uneven shape on the surface are unlikely to occur.

It is the cross-sectional schematic diagram which expanded the acrylic resin film and its surface. It is the cross-sectional schematic diagram which showed an example of the polarizing plate. It is the schematic diagram which showed an example of the manufacturing method of an acrylic resin film. It is the cross-sectional schematic diagram which showed an example of the liquid crystal display device which uses a polarizing plate. It is the cross-sectional schematic diagram which showed the sample used for the T-type peel test of the Example. It is the graph which showed the measurement result of the adhesive force of an acrylic resin film. It is a microscope picture of the surface of the acrylic resin film before performing a corona treatment. It is a microscope picture of the surface of the acrylic resin film after performing a corona treatment.

  Hereinafter, some embodiments of the present invention will be described with reference to the drawings. In addition, this invention is not limited by the member, arrangement | positioning, etc. which are demonstrated below, These members etc. can be suitably changed in accordance with the meaning of this invention.

  Hereinafter, the acrylic resin film will be described. The acrylic resin film of the present invention is a sheet-like film made of an acrylic resin composition in which rubber elastic body particles are blended with an acrylic resin.

  Fig.1 (a) is the cross-sectional schematic diagram which showed the cross-sectional shape of the acrylic resin film. FIG. 1B is a schematic cross-sectional view showing enlarged regions R1 and R2 on the surface of the acrylic resin film of FIG. 1A. The left side is the region R1 and the right side is the region R2. It is an enlarged view. As shown in this figure, from the surface of the acrylic resin film 25, it has the uneven | corrugated shape from which the one part area | region of the rubber elastic body particle protruded. One surface of the acrylic resin film 25 is a smooth surface 25a in which the surface area of the rubber elastic particles protruding from the surface is relatively small, and the surface on the opposite side is the surface area of the rubber elastic particles protruding from the surface. The rough surface 25b is larger than the smooth surface 25a.

  The surface area of the rubber elastic particles protruding from the film surface can be expressed using an index such as surface roughness. As the surface roughness, indices such as arithmetic average roughness (Ra), maximum height (Ry), and ten-point average roughness (Rz) can be employed.

  The difference in arithmetic average roughness (Ra) between the rough surface 25b and the smooth surface 25a is preferably about 5 nm to 100 nm. When the difference in arithmetic average roughness (Ra) is less than 5 nm, the surface roughness becomes the same, so that the polarizing film 21 is laminated on one surface via an adhesive layer 28 as shown in FIG. However, when the functional layer 26 is formed on the other surface, the adhesive strength is lowered and the polarizing film 21 is easily peeled off, or the unevenness is increased on the side of the functional layer 26 and the visibility is deteriorated. Tend. On the other hand, the acrylic resin film 25 in which the difference in arithmetic average roughness (Ra) exceeds 100 nm tends to whiten the film and tends to deteriorate the optical characteristics.

  Thus, by making the surface areas of the rubber elastic particles protruding from the film surface different on both surfaces of the acrylic resin film 25, a polarizing film is formed on one surface of the acrylic resin film 25 like a polarizing plate described later. 21 is adhered, and a specific effect is exhibited when the functional layer 26 is formed on the other surface. Hereinafter, the polarizing plate provided with the acrylic resin film 25 will be described.

(Polarizing plate 20)
As shown in FIG. 2, the acrylic resin film 25 can be used as a film constituting the polarizing plate 20. In this figure, the example which used the acrylic resin film 25 as an outer side protective film of the polarizing film 21 is shown. The polarizing plate 20 has a layer structure in which an acrylic resin film 25, a polarizing film 21, an inner resin film 23, and an adhesive layer 27 are laminated in this order. Both the acrylic resin film 25 and the polarizing film 21 and the polarizing film 21 and the inner resin film 23 are bonded by an adhesive layer 28.

  The polarizing film 21 is bonded to the rough surface 25 b side of the acrylic resin film 25 via an adhesive layer 28. Since the rough surface 25b has a relatively large surface area of the rubber elastic particles protruding from the film surface, when an adhesive is applied to the rough surface 25b, the adhesive is grooved on the uneven surface of the rubber elastic particle surface. The rubber elastic body particles play a role like a wedge by infiltrating into the gaps and hardening, so that they are firmly bonded by the so-called “anchor effect”. For this reason, the adhesive force between the acrylic resin film 25 and the polarizing film 21 is increased, and both are not easily peeled off.

  On the other hand, the functional layer 26 is formed on the smooth surface 25 a side of the acrylic resin film 25. Examples of the functional layer 26 include an antiglare layer, a hard coat layer, an antireflection layer / low reflection layer, an antifouling layer, a dustproof layer / antistatic layer, and the like. When these functional layers 26 are formed, it is preferable that the surface of the acrylic resin film 25 has less irregularities. For example, in the case of an antiglare layer, in order to scatter light transmitted through the antiglare layer, light transmissive particles as a filler are blended in the resin composition, and this is applied to the surface of the acrylic resin film 25. However, if the surface of the acrylic resin film 25 is uneven, light transmissive particles accumulate in the recesses, resulting in local differences in light scattering and visibility. Gets worse. Moreover, even if it is the functional layer 26 which does not use fillers, such as a hard-coat layer, when the uneven | corrugated shape of the surface of the acrylic resin film 25 is comparatively large, this will be visible to an observer and visibility will deteriorate. Sometimes.

  Therefore, it is preferable that the surface of the acrylic resin film 25 on which the functional layer 26 is formed has as few asperities as possible, and thus the functional layer 26 is formed on the smooth surface 25a side. This is preferable because problems such as deterioration in visibility due to surface irregularities are reduced.

(1) Acrylic resin film 25;
Next, the acrylic resin film 25 will be described. The acrylic resin film 25 is a film made of an acrylic resin and can be used for applications such as a protective film for the polarizing plate 20. Here, acrylic resin means (meth) acrylic resin and is a concept including both acrylic resin and methacrylic resin. Hereinafter, the acrylic resin will be described.

(1-1) Acrylic resin;
As described above, the acrylic resin is a (meth) acrylic resin and means a polymer of acrylic acid ester or methacrylic acid ester. As the polymer of the methacrylic acid ester, for example, a polymer composed mainly of an alkyl methacrylate is preferable. The monomer composition of the alkyl methacrylate is preferably 70% by weight or more, more preferably 80% by weight or more, and still more preferably 90% by weight or more, based on the total 100% by weight of all monomers. And alkyl methacrylate is 99% by weight or less. The acrylic resin may be a homopolymer of alkyl methacrylate, or a copolymer of 50% by weight or more of alkyl methacrylate and 50% by weight or less of a monomer other than alkyl methacrylate. Also good. As the alkyl methacrylate, those having 1 to 4 carbon atoms of the alkyl group are usually used, and among them, methyl methacrylate is preferably used.

  The monomer other than alkyl methacrylate may be a monofunctional monomer having one polymerizable carbon-carbon double bond in the molecule, or two or more polymerizable carbons in the molecule. -A polyfunctional monomer having a carbon double bond may be used. In particular, monofunctional monomers are preferably used. Examples thereof include alkyl acrylates such as methyl acrylate and ethyl acrylate, styrene monomers such as styrene and alkyl styrene, acrylonitrile and methacrylonitrile. Such unsaturated nitriles. When using alkyl acrylate as a copolymerization component, the carbon number is 1-8 normally.

  The acrylic resin preferably does not have a glutarimide derivative, a glutaric anhydride derivative, a lactone ring structure, or the like. These acrylic resins may not have sufficient mechanical strength and heat-and-moisture resistance as the acrylic resin film 25 in some cases.

(1-2) Rubber elastic particles;
In order to improve flexibility and handleability, rubber-based elastic particles are blended in the acrylic resin. The rubber elastic particles are particles containing a rubber elastic body, and may be particles composed only of a rubber elastic body, or may be particles having a multilayer structure having a rubber elastic body layer. Examples of rubber elastic bodies include olefin-based elastic polymers, diene-based elastic polymers, styrene-diene-based elastic copolymers, and acrylic-based elastic polymers. Among these, an acrylic elastic polymer is preferable from the viewpoint of the surface hardness, light resistance, and transparency of the acrylic resin film 25.

  The acrylic elastic polymer is preferably a polymer mainly composed of alkyl acrylate, and may be a homopolymer of alkyl acrylate, or may be a single polymer other than alkyl acrylate of 50% by weight or more and alkyl acrylate. A copolymer with 50% by weight or less of the monomer may be used. As the alkyl acrylate, those having 4 to 8 carbon atoms in the alkyl group are usually used. Examples of monomers other than alkyl acrylate include alkyl methacrylates such as methyl methacrylate and ethyl methacrylate, styrene monomers such as styrene and alkyl styrene, acrylonitrile and methacrylonitrile. Monofunctional monomers such as unsaturated nitriles, alkenyl esters of unsaturated carboxylic acids such as allyl (meth) acrylate and methallyl (meth) acrylate, dialkenyl esters of dibasic acids such as diallyl maleate, And polyfunctional monomers such as unsaturated carboxylic acid diesters of glycols such as alkylene glycol di (meth) acrylate.

  The rubber elastic particle containing the acrylic elastic polymer is preferably a particle having a multilayer structure having an acrylic elastic polymer layer, and a polymer mainly composed of alkyl methacrylate outside the acrylic elastic polymer. It may be a two-layer structure having the above-mentioned layer, or a three-layer structure having a polymer layer mainly composed of alkyl methacrylate inside the acrylic elastic polymer. In addition, the example of the monomer composition of the polymer mainly composed of alkyl methacrylate constituting the layer formed on the outside or inside of the acrylic elastic polymer is the alkyl methacrylate mentioned above as an example of the acrylic resin. It is the same as that of the example of the monomer composition of the polymer which has as a main component. Such acrylic rubber elastic particles having a multilayer structure can be produced, for example, by the method described in Japanese Patent Publication No. 55-27576.

  As the rubber elastic particles, those having a number average particle diameter of 10 to 300 nm of the rubber elastic bodies contained therein can be used. Thereby, when the acrylic resin film 25 is laminated | stacked on the polarizing film 21 using an adhesive agent, the acrylic resin film 25 can be made hard to peel from the adhesive bond layer 28. FIG. The number average particle diameter of the rubber elastic body is preferably 50 nm or more and 250 nm or less.

  In the case of rubber elastic particles in which the outermost layer is a polymer mainly composed of methyl methacrylate and the acrylic elastic polymer is encapsulated therein, the rubber elastic particles are mixed with the base acrylic resin. The outermost layer is mixed with the base acrylic resin. Therefore, in the cross section, when the acrylic elastic polymer is dyed with ruthenium oxide and observed with an electron microscope, the rubber elastic particles can be observed as particles excluding the outermost layer. Specifically, in the case of using rubber elastic particles having a two-layer structure in which the inner layer is an acrylic elastic polymer and the outer layer is a polymer mainly composed of methyl methacrylate, the inner layer is an acrylic elastic polymer. The portion is dyed and observed as particles having a single layer structure. Further, the rubber elastic particles having a three-layer structure in which the innermost layer is a polymer mainly composed of methyl methacrylate, the intermediate layer is an acrylic elastic polymer, and the outermost layer is a polymer mainly composed of methyl methacrylate. When is used, the center part of the innermost layer particle is not dyed, and only the acrylic elastic polymer part of the intermediate layer is dyed and observed as a two-layered particle.

  In the present specification, the number average particle diameter of the rubber elastic particles is, as described above, when the rubber elastic particles are mixed with the base resin and the cross section is dyed with ruthenium oxide, and is dyed in a substantially circular shape. It is the number average value of the diameters of the parts observed in FIG.

  In the acrylic resin composition forming the acrylic resin film 25, the blending amount of the rubber elastic body particles is not particularly limited. For example, a rubber elastic body having a number average particle diameter of 10 to 300 nm is added to a transparent acrylic resin. Those containing 25 to 45% by weight of particles are preferred.

  The acrylic resin composition is produced, for example, by obtaining rubber elastic particles and then polymerizing a monomer as a raw material of the acrylic resin in the presence thereof to produce a base acrylic resin. Alternatively, after obtaining rubber elastic particles and an acrylic resin, they may be produced by mixing them by melt kneading or the like.

  As necessary, the acrylic resin composition includes a colorant such as a pigment or a dye, a fluorescent brightener, a dispersant, a heat stabilizer, a light stabilizer, an infrared absorber, an ultraviolet absorber, an antistatic agent, You may contain compounding agents, such as antioxidant, a lubricant, and a solvent.

  The ultraviolet absorber is added to improve durability by absorbing ultraviolet rays of 400 nm or less. As the ultraviolet absorber, known ones such as a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, and an acrylonitrile ultraviolet absorber can be used. Among them, 2,2'-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol), 2- (2'-hydroxy-3 ' -Tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2,4-di-tert-butyl-6- (5-chlorobenzotriazol-2-yl) phenol, 2,2'-dihydroxy- 4,4′-dimethoxybenzophenone, 2,2 ′, 4,4′-tetrahydroxybenzophenone and the like are preferably used. Among these, 2,2′-methylenebis (4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol) is particularly preferable.

  The concentration of the ultraviolet absorber can be selected in such a range that the transmittance of the acrylic resin film 25 having a wavelength of 370 nm or less is preferably 10% or less, more preferably 5% or less, and further preferably 2% or less. Examples of the method of containing the ultraviolet absorber include a method of previously blending the ultraviolet absorber into the acrylic resin; a method of supplying it directly at the time of melt extrusion molding, and any method may be employed.

  Examples of infrared absorbers include nitroso compounds, metal complexes thereof, cyanine compounds, squarylium compounds, thiol nickel complex compounds, phthalocyanine compounds, naphthalocyanine compounds, triallylmethane compounds, imonium compounds, diimonium compounds, Infrared absorption of naphthoquinone compounds, anthraquinone compounds, amino compounds, aminium salt compounds, carbon black, indium tin oxide, antimony tin oxide, metal oxides belonging to Group 4A, 5A or 6A, carbides, borides, etc. An agent etc. can be mentioned. These infrared absorbers are preferably selected so as to be able to absorb the entire infrared ray (light having a wavelength in the range of about 800 nm to 1100 nm), and two or more types may be used in combination. The amount of the infrared absorber can be appropriately adjusted so that, for example, the light transmittance at a wavelength of 800 nm or more of the acrylic resin film 25 is 10% or less.

  The glass transition temperature Tg of the acrylic resin composition is preferably in the range of 80 to 120 ° C. Furthermore, the acrylic resin composition preferably has a high surface hardness when formed into a film, specifically, a pencil hardness (with a load of 500 g, conforming to JIS K5600-5-4) of B or higher. .

  In addition, the acrylic resin composition preferably has a flexural modulus (JIS K7171) of 1500 MPa or less from the viewpoint of flexibility of the acrylic resin film 25. The flexural modulus is more preferably 1300 MPa or less, and still more preferably 1200 MPa or less. This flexural modulus varies depending on the type and amount of acrylic resin and rubber elastic particles in the acrylic resin composition. For example, as the content of rubber elastic particles increases, the flexural modulus generally decreases. . In addition, the use of a copolymer of an alkyl methacrylate and an alkyl acrylate as an acrylic resin generally has a lower flexural modulus than using an alkyl methacrylate homopolymer.

  In addition, the elastic elastic polymer particles having the two-layer structure are generally used as the elastic rubber particles, rather than the acrylic elastic polymer particles having the two-layer structure. In general, the flexural modulus is smaller when the acrylic elastic polymer particles having a layer structure are used. Further, in the rubber elastic body particles, as the average particle diameter of the rubber elastic body is smaller or the amount of the rubber elastic body is larger, the bending elastic modulus is generally smaller. Therefore, it is preferable to adjust the kind and amount of the acrylic resin and the rubber elastic body particles within the predetermined range so that the flexural modulus is 1500 MPa or less.

  In the case where the acrylic resin film 25 has a multilayer structure, the layer that can exist other than the layer of the acrylic resin composition is not particularly limited in its composition. For example, an acrylic resin that does not contain rubber elastic particles or a composition thereof Or a layer made of an acrylic resin composition in which the content of the rubber elastic particles and the average particle diameter of the rubber elastic bodies in the rubber elastic particles are outside the above-mentioned regulations. Good.

  Typically, it has a two-layer or three-layer structure, and may be a two-layer structure including, for example, an acrylic resin composition layer / an acrylic resin not containing rubber elastic particles or a layer of the composition. Further, it may have a three-layer structure comprising an acrylic resin composition layer / an acrylic resin not containing rubber elastic particles or a layer of the composition / an acrylic resin composition layer. The acrylic resin film 25 having a multilayer structure may have a surface of the acrylic resin composition layer as a bonding surface with the polarizing film 21.

  Moreover, when making the acrylic resin film 25 into a multilayer structure, you may mutually differ content of rubber elastic-body particle | grains or each layer of the said compounding agent. For example, a layer containing an ultraviolet absorber and / or an infrared absorber and a layer not containing an ultraviolet absorber and / or an infrared absorber may be laminated with this layer interposed therebetween. Further, the content of the ultraviolet absorber in the layer of the acrylic resin composition may be higher than the content of the ultraviolet absorber in the layer of the acrylic resin not containing rubber elastic particles or the composition thereof. Well, specifically, the former is preferably 0.5 to 10% by weight, more preferably 1 to 5% by weight, and the latter is preferably 0 to 1% by weight, more preferably 0 to 0.5% by weight. As a result, ultraviolet rays can be efficiently blocked without deteriorating the color tone of the polarizing plate 20, and a decrease in the degree of polarization during long-term use can be prevented.

  The acrylic resin film 25 may be non-oriented or unstretched or may be stretched. When the stretching process is not performed, the thickness of the polarizing plate 20 is likely to increase because the thickness is increased. On the other hand, the handling property of the acrylic resin film 25 is improved because the thickness is increased. Such an acrylic resin film 25 can be obtained from an unstretched film (raw film) obtained by forming an acrylic resin composition. On the other hand, when stretched, the phase difference is easily developed, but stretching has the advantage that the thickness of the acrylic resin film 25 is reduced and the rigidity is improved. The stretched film can be produced by stretching an unstretched film by an arbitrary method.

  The acrylic resin can be formed into an unstretched film by any method. This unstretched film is preferably transparent and substantially free of in-plane retardation. Examples of the film forming method include an extrusion method in which a molten resin is extruded to form a film, and a solvent cast method in which a solvent dissolved in an organic solvent is cast on a flat plate and then the solvent is removed to form a film. Etc. can be adopted.

  As a specific example of the extrusion molding method, for example, there is a method of forming a film in a state where an acrylic resin composition is sandwiched between two rolls. At this time, by varying the rigidity of the roll surface, it is possible to make one surface of the acrylic resin film the smooth surface 25a and the other surface the rough surface 25b.

  FIG. 3 is a schematic diagram illustrating a method for producing the acrylic resin film 25 by an extrusion molding method. As shown in this figure, an acrylic resin composition heated to a molten state is extruded from a die 11 into a sheet, and is narrowed by a cooling roll 12 and an elastic roll 13 to form a sheet and cooled. The cooling roll 12 is made of a material having high rigidity such as metal, and the elastic roll 13 is made of an elastic material having a higher elastic modulus than the cooling roll 12 such as rubber. As the elastic roll 13, a metal elastic roll, a rubber roll, or the like can be used. As the metal elastic roll, a known one can be used, for example, a surface whose surface is made of a metal material and a space between the surface metal material and the shaft roll is filled with an elastic material such as a fluid or rubber. Can do. The rubber roll is a roll whose surface is formed of an elastic material such as rubber. In addition, it is preferable that the surface of the cooling roll 12 is a mirror surface roll. Thereby, the film excellent in surface smoothness can be obtained. The cooling temperature of the cooling roll 12 is not particularly limited as long as it is a temperature at which the molten resin can be cured to form a film, but it is usually within a range of 10 to 100 ° C.

  The surface roughness of the cooling roll 12 is preferably such that the roughness represented by the standard sequence of the maximum height is 0.2S or less. Further, the surface roughness of the elastic roll 13 is preferably such that the roughness expressed by the standard sequence of the maximum height is 0.2S or less.

  The sheet-like acrylic resin film 25 formed by the rolls 12 and 13 has a smooth surface 25a as a surface that contacts the cooling roll 12 and a rough surface 25b as a surface that contacts the elastic roll 13. This is because the elastic roll 13 has a high elastic modulus in the radial direction and a low indentation resistance, so that the rubber elastic particles are resisted against the pressing force on the surface of the elastic roll 13 even when grounded on the surface of the acrylic resin film 25. This is because it easily protrudes from the film surface, and as a result, irregularities are likely to occur on the film surface. On the contrary, since the cooling roll 12 has high surface rigidity, the elastic rubber particles protruding from the surface of the acrylic resin film 25 are easily pushed into the surface of the cooling roll 12 so that the film surface is smooth. It is because it is easy to become. The cooling roll 12 corresponds to the first roll of the present invention, and the elastic roll 13 corresponds to the second roll of the present invention.

  The acrylic resin film 25 formed into a sheet shape is wound up in a roll shape by a winding roll 19. The raw material of the acrylic resin film 25 is drawn out into a sheet shape as necessary, and used for manufacturing an optical member such as the polarizing plate 20.

  In addition, when obtaining the thing of a multilayer structure as the acrylic resin film 25, what is necessary is just to film-form an acrylic resin composition after multilayer extrusion with another acrylic resin composition. The thickness of the unstretched film thus obtained is preferably 5 to 200 μm, more preferably 10 μm to 85 μm.

  The unstretched film made of an acrylic resin can be stretched by a known method such as uniaxial stretching or biaxial stretching as necessary. Examples of the stretching method include a tenter method using a tenter stretching machine. Biaxial stretching may be simultaneous biaxial stretching in which stretching is performed simultaneously in two stretching directions, or sequential biaxial stretching in which stretching is performed in a predetermined direction and then stretching in another direction.

  Next, the haze value of the acrylic resin film 25 will be described. The haze value is the ratio of the diffuse light transmittance to the total light transmittance when the film is irradiated with visible light. It is recognized that the smaller the haze value is, the better the film is. Moreover, an internal haze value shows the value which deducted the haze value (external haze value) resulting from the surface shape of a film from the haze value of a film.

  As described above, the haze value of the acrylic resin film 25 has an internal haze value of 1.0% or less, more preferably 0.5% or less, and an external haze value of 5% or less. If the internal haze value exceeds 1.0% and the external haze value exceeds 5%, the light transmitted through the film is scattered, and the display characteristics may be deteriorated when bonded to a liquid crystal display device.

  The method for producing the acrylic resin film 25 is not limited to the method of narrowing the pressure with the cooling roll 12 and the elastic roll 13 described above. For example, two types of acrylic resin compositions, an acrylic resin composition with a high blending concentration of rubber elastic particles and an acrylic resin composition with a low blending concentration, are prepared, and each acrylic resin composition is used. The method etc. which laminate | stack the produced sheet-like film are also mentioned. In this method, the sheet-like film side produced with an acrylic resin composition having a high blending concentration of rubber elastic particles becomes the rough surface 25b, and the sheet-like film side produced with an acrylic resin composition having a low blending concentration becomes the smooth surface 25a. Become.

(2) functional layer 26;
A functional layer 26 can be formed on the surface of the acrylic resin film 25. Examples of the functional layer 26 include a hard coat layer, an antiglare layer, an antireflection / low reflection layer, and a dustproof / antistatic layer. As described above, these functional layers 26 are preferably formed on the surface of the smooth surface 25 a of the acrylic resin film 25.

[Hard coat layer]
The hard coat layer is a layer for protecting the acrylic resin film 25 by imparting scratch resistance, chemical resistance and the like to the surface of the acrylic resin film 25. As the hard coat layer, known ones can be appropriately employed. For example, a hard coat layer obtained by curing a layer containing an active energy ray-curable compound can be used. The active energy ray-curable compound is a compound having a property of being cured by irradiation with active energy rays such as an electron beam and ultraviolet rays. Examples of such an active energy ray-curable compound include an electron beam curable compound that is cured by irradiation with an electron beam, and an ultraviolet curable compound that is cured by irradiation with ultraviolet rays. These compounds are the same compounds as the main component of the hard coat agent used for forming a normal hard coat layer, and examples thereof include (meth) acrylic resins. In particular, among (meth) acrylic resins, those containing a polyfunctional acrylate compound as a main component are preferable.

  Here, the polyfunctional acrylate compound is a compound having at least two acryloyloxy groups or methacryloyloxy groups in the molecule, and specifically includes ethylene glycol diacrylate, diethylene glycol diacrylate, and 1,6-hexane. Diol diacrylate, Neopentyl glycol diacrylate, Trimethylol propane triacrylate, Trimethylol ethane triacrylate, Tetramethylol methane triacrylate, Tetramethylol methane tetraacrylate, Pentaglycerol triacrylate, Pentaerythritol triacrylate, Pentaerythritol tetraacrylate, Glycerin Triacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate Rate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tris (acryloyloxyethyl) isocyanurate, ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentyl glycol dimethacrylate, trimethylolpropane Trimethacrylate, trimethylolethane trimethacrylate, tetramethylolmethane trimethacrylate, tetramethylolmethane tetramethacrylate, pentaglycerol trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerin trimethacrylate, dipentaerythritol trimethacrylate, dipe Taerythritol tetramethacrylate, dipentaerythritol pentamethacrylate, dipentaerythritol hexamethacrylate, tris (methacryloyloxyethyl) isocyanurate, phosphazene acrylate compounds or phosphazene compounds in which acryloyloxy or methacryloyloxy groups are introduced into the phosphazene ring of phosphazene compounds Methacrylate compound, urethane acrylate compound or urethane methacrylate compound obtained by reaction of polyisocyanate having at least two isocyanate groups in the molecule and polyol compound having at least one acryloyloxy group or methacryloyloxy group and hydroxyl group, in the molecule At least two carboxylic acid halides and at least one acryloyl Examples include polyester acrylate compounds, polyester methacrylate compounds obtained by reaction with a polyol compound having an oxy group or a methacryloyloxy group and a hydroxyl group, and oligomers such as dimers and trimers of the above-mentioned compounds.

  These compounds are used alone or in admixture of two or more. In addition to the above polyfunctional (meth) acrylate, the hydroxyethyl (meth) is preferably 10.0% by weight or less based on the active energy ray-curable resin solid content at the time of curing the coating material for the hard coat layer. Select from acrylate, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, glycidyl (meth) acrylate, etc. At least one monofunctional (meth) acrylate may be blended.

  Moreover, a polymerizable oligomer can be added to the hard coat layer for the purpose of adjusting the hardness. Such oligomers include terminal (meth) acrylate polymethyl methacrylate, terminal styryl poly (meth) acrylate, terminal (meth) acrylate polystyrene, terminal (meth) acrylate polyethylene glycol, terminal (meth) acrylate acrylonitrile-styrene copolymer, Examples thereof include macromonomers such as terminal (meth) acrylate styrene-methyl (meth) acrylate copolymer. The content thereof is preferably 5.0 to 50.0% by weight with respect to the solid content at the time of curing of the coating composition.

  The active energy ray curable compound may be used as a solution mixed with a solvent. The active energy ray-curable compound and its solution may be commercially available as a hard coat agent. As a commercially available hard coat agent, specifically, “NK Hard M101” (manufactured by Shin-Nakamura Chemical Co., Ltd., urethane acrylate compound), “NK Ester A-TMM-3L” (manufactured by Shin-Nakamura Chemical Co., Ltd.) Tetramethylolmethane triacrylate), “NK Ester A-9530” (manufactured by Shin-Nakamura Chemical Co., Ltd., dipentaerythritol hexaacrylate), “KAYARAD (registered trademark) DPCA series” (manufactured by Nippon Kayaku Co., Ltd., dipenta Derivatives of erythritol hexaacrylate compound), “Aronix (registered trademark) M-8560” (manufactured by Toa Gosei Co., Ltd., polyester acrylate compound), “New Frontier (registered trademark) TEICA” (manufactured by Daiichi Kogyo Seiyaku Co., Ltd.) Tris (acryloyloxyethyl) isocyanurate), "PPZ" (Kyoeisha) Manabu Ltd., phosphazene methacrylate compound), and the like.

  In order to form the hard coat layer on the surface of the acrylic resin film 25, for example, a composition containing an active energy ray-curable compound may be applied to the surface of the substrate and irradiated with active energy rays. Such a composition can be obtained by mixing an active energy ray-curable compound with an additive or the like.

  Although the film thickness of a hard-coat layer can be set suitably, it is preferable that it is 10 micrometers or less, for example. Moreover, the composition containing an active energy ray hardening compound is normally diluted with a solvent and used. In this case, the active energy ray-curable compound may be diluted with a solvent after mixing various additives for imparting surface smoothness such as silicone oil, or the active energy ray-curable compound is diluted with a solvent. You may mix with an additive later, and you may mix the active energy ray hardening compound and the additive previously diluted with the solvent. Moreover, you may mix the active energy ray-curable compound previously diluted with the solvent, and the additive previously diluted with the solvent. The composition after mixing may be further stirred.

  Further, from the viewpoint of facilitating coating, the composition containing the active energy ray-curable compound is preferably diluted with an appropriate solvent. Solvents include aliphatic hydrocarbons such as hexane and octane, aromatic hydrocarbons such as toluene and xylene, alcohols such as ethanol, 1-propanol, isopropanol and 1-butanol, ketones such as methyl ethyl ketone and methyl isobutyl ketone, It can be appropriately selected from esters such as ethyl acetate and butyl acetate, cellosolves and the like. These organic solvents may be used in combination of several kinds as required. Since it is necessary to evaporate the organic solvent after coating, the boiling point of the solvent is preferably in the range of 70 ° C to 200 ° C. The type and amount of the solvent used are appropriately selected according to the type and amount of the active energy ray curable compound to be used, the material and shape of the substrate, the coating method, the thickness of the target hard coat layer, and the like.

  The composition containing the active energy ray-curable compound may contain a polymerization initiator. When ultraviolet rays or visible rays are used as active energy rays, a photopolymerization initiator is usually used as a polymerization initiator.

  Examples of the photopolymerization initiator include acetophenone, acetophenone benzyl cateal, anthraquinone, 1- (4-isopropylphenyl-2-hydroxy-2-methylpropan-1-one, carbazole, xanthone, 4-chloro. Benzophenone, 4,4'-diaminobenzophenone, 1,1-dimethoxydeoxybenzoin, 3,3'-dimethyl-4-methoxybenzophenone, thioxanthone, 2,2-dimethoxy-2-phenylacetophenone, 1- (4-dodecylphenyl) ) -2-hydroxy-2-methylpropan-1-one, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropan-1-one, triphenylamine, 2,4,6 -Trimethylbenzoyldiphenylphosphine oxide, 1-hydroxy Rohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, fluorenone, fluorene, benzaldehyde, benzoin ethyl ether, benzoisopropyl ether, benzophenone, Michler ketone, 3-methylacetophenone, 3,3 ′, 4,4'-tetra-tert-butylperoxycarbonylbenzophenone (BTTB), 2- (dimethylamino) -1- [4- (morpholinyl) phenyl] -2-phenylmethyl) -1-butanone, 4-benzoyl -4'-methyldiphenyl sulfide, benzyl and the like. The photopolymerization initiator may be used in combination with a dye sensitizer. Examples of the dye sensitizer include xanthene, thioxanthene, coumarin, and ketocoumarin. Examples of the combination of the photopolymerization initiator and the dye sensitizer include a combination of BTTB and xanthene, a combination of BTTB and thioxanthene, a combination of BTTB and coumarin, and a combination of BTTB and ketocoumarin.

  When using a photoinitiator, the usage-amount is 0.1 weight part or more per 100 weight part of active energy ray hardening compounds. When the amount is less than 0.1 part by weight, the curing rate tends to be difficult to increase as compared with the case where no photopolymerization initiator is used. In addition, the upper limit of the usage-amount of a photoinitiator is 10 weight part per 100 weight part of active energy ray-curable compounds.

  The composition containing the active energy ray curable compound may contain an antistatic agent. By containing an antistatic agent, a hard coat substrate having antistatic performance and antistatic performance can be obtained. Examples of the antistatic agent include a surfactant, an antistatic agent composed of a conductive polymer, and conductive particles. Examples of the conductive particles include particles of indium-tin-composite oxide (ITO), tin oxide doped with antimony, and the like. These antistatic agents are used alone or in combination of two or more.

  In addition, such a composition contains organic compounds containing bromine atoms, fluorine atoms, sulfur atoms, benzene rings, inorganic oxide fine particles such as tin oxide, antimony oxide, titanium oxide, zirconium oxide, zinc oxide, and silicon oxide. When it contains, the refractive index of the hard-coat layer obtained can be adjusted.

  A layer containing the active energy ray-curable compound can be formed by applying the composition onto the acrylic resin film 25 and then drying the composition. The coating can be performed by an ordinary method such as a micro gravure coating method, a roll coating method, a dipping coating method, a spin coating method, a die coating method, a cast transfer method, a flow coating method, or a spray coating method.

  Thereafter, the active energy ray-curable compound constituting the layer formed on the surface of the base material is cured by irradiating the activation energy ray, and the intended hard coat layer is obtained. Examples of the active energy rays include electron beams, ultraviolet rays, and visible rays, and are appropriately selected according to the type of active energy ray curable compound to be used. The active energy ray may be irradiated in the same manner as in the formation of a normal hard coat layer. The intensity | strength of the active energy ray to irradiate, irradiation time, etc. are suitably selected according to the kind of curable compound to be used, the thickness of the layer containing a curable compound, etc. The active energy ray may be irradiated in an inert gas atmosphere. In order to irradiate the active energy ray in a nitrogen atmosphere, for example, the active energy ray may be irradiated in a container sealed with an inert gas. As the inert gas, nitrogen gas, argon gas, or the like can be used. Furthermore, it is also useful to form an antireflection layer or a low reflection layer, which will be described later, on the surface of the hard coat layer. In this case, the antireflection layer and the low reflection layer can be laminated in a single layer or multiple layers on the surface of the hard coat layer.

[Anti-glare layer]
The antiglare layer is a layer for preventing reflection of external light by scattering and reflecting light. A well-known thing can be employ | adopted suitably as a glare-proof layer. In the present embodiment, the antiglare layer has a fine concavo-convex shape on the surface, and is formed using a resin composition containing one or more kinds of translucent fine particles in the translucent resin. More specifically, for such an antiglare layer, for example, a translucent resin solution in which translucent fine particles as a filler are dispersed is applied on the acrylic resin film 25 to adjust the coating film thickness. Thus, the transparent fine particles are formed so as to be convex. In the present invention, “translucency” means that light can be transmitted almost regardless of the presence or absence of scattering inside the substance.

[[Translucent fine particles]]
The translucent fine particles preferably have a particle size of 0.5 to 5 μm and a difference in refractive index from the translucent resin of 0.02 to 0.2. Moreover, it is preferable that a translucent fine particle is mix | blended in the ratio of 3 to 30 weight part with respect to 100 weight part of translucent resin. The haze of the antiglare layer is preferably 5 to 50%. The haze of the antiglare layer is measured by a method according to JIS K 7361.

  Examples of the light-transmitting fine particles include silica-based fine particles and resin fine particles. Among these, it is preferable to use resin fine particles because the specific gravity is close to that of the translucent resin and hardly settles and the surface free energy is small and relatively easy to disperse. As resin fine particles, melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), methyl methacrylate / styrene copolymer resin beads (refractive index 1.50-1.59), Polyethylene beads (refractive index 1.53), polycarbonate beads, polyethylene beads, polystyrene beads, vinyl chloride beads and the like are used. As described above, those resin fine particles having a particle diameter of 0.5 to 5 μm are appropriately selected and used. Examples of the silica-based fine particles include agglomerated silica. Agglomerated silica is obtained by agglomerating tens to hundreds of colloidal silica particles. The silica particle diameter is 30 nm or less, preferably about 5 to 25 nm, and the aggregated particle diameter is about 1 to 5 μm.

  The difference in refractive index between the translucent fine particles and the translucent resin is preferably 0.02 to 0.2, and more preferably 0.04 to 0.1. When the difference in refractive index is less than 0.02, the difference in refractive index between the two is too small and it is difficult to obtain a sufficient light diffusion effect. Moreover, when the refractive index difference is larger than 0.2, the light diffusing ability becomes too high and the entire acrylic resin film 25 is whitened, which is not preferable.

  The particle diameter of the translucent fine particles is preferably 0.5 to 5 μm, more preferably 1 to 4 μm. When the particle size of the light-transmitting fine particles is less than 0.5 μm, it is difficult to obtain a light diffusion effect unless the amount of the light-transmitting fine particles to be added to the light-transmitting resin is significantly increased. Irregularities on the surface of the layer are not easily formed, and it is difficult to obtain a sufficient antiglare effect. Moreover, when the particle size of the light-transmitting fine particles is 5 μm or more, the surface shape of the antiglare layer becomes rough and the haze value is significantly increased.

  The amount of translucent fine particles added to 100 parts by weight of the translucent resin is preferably 3 to 30 parts by weight, more preferably 5 to 20 parts by weight. When the addition amount is less than 3 parts by weight, it is difficult to obtain a sufficient light diffusion effect. Moreover, when the addition amount exceeds 30 parts by weight, there is a problem in that the entire acrylic resin film 25 is whitened, which is not preferable.

  By regulating the refractive index, particle size, and blending amount of the translucent fine particles as described above, it is possible to prevent glare on the surface without reducing the transmission sharpness even in a high haze region of the antiglare layer. Further, glare can be prevented even in a low haze region while maintaining high transmission clarity.

  When the translucent fine particles are blended with the translucent resin, the translucent fine particles may settle depending on the viscosity of the resin composition. In this case, it is also effective to add an inorganic filler such as silica as an anti-settling agent. In addition, although an inorganic filler expresses the remarkable sedimentation prevention effect with the increase in addition amount, the transparency of a glare-proof layer falls remarkably. For this reason, it is preferable to make the particle size of an inorganic filler into 0.5 micrometer or less, and mix | blend the quantity of 0.1 weight% or less.

[[Translucent resin]]
As the translucent resin for dispersing the translucent fine particles, an ultraviolet curable resin, a thermosetting resin, an electron beam curable resin, and the like can be used. From the viewpoint of productivity, an ultraviolet curable resin is preferably used. The A commercially available UV curable resin can be used. For example, “Irgacure 907”, “Irgacure 184” (above, manufactured by Ciba Specialty Chemicals) alone or in combination of two or more polyfunctional acrylate compounds such as trimethylolpropane triacrylate and pentaerythritol tetraacrylate A mixture with a photopolymerization initiator such as “Lucirin TPO” (manufactured by BASF) can be used as an ultraviolet curable resin. After the light-transmitting fine particles are dispersed in such an ultraviolet curable resin, the resin composition is applied onto the resin base film and irradiated with ultraviolet rays, whereby the light-transmitting fine particles are dispersed in the light-transmitting resin. An anti-glare layer can be formed.

  Here, the polyfunctional acrylate compound is a compound having at least two acryloyloxy groups or methacryloyloxy groups in the molecule, and specifically includes ethylene glycol diacrylate, diethylene glycol diacrylate, and 1,6-hexane. Diol diacrylate, Neopentyl glycol diacrylate, Trimethylol propane triacrylate, Trimethylol ethane triacrylate, Tetramethylol methane triacrylate, Tetramethylol methane tetraacrylate, Pentaglycerol triacrylate, Pentaerythritol triacrylate, Pentaerythritol tetraacrylate, Glycerin Triacrylate, dipentaerythritol triacrylate, dipentaerythritol tetraacrylate Rate, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, tris (acryloyloxyethyl) isocyanurate; ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, 1,6-hexanediol dimethacrylate, neopentylglycol dimethacrylate, trimethylolpropane Trimethacrylate, trimethylolethane trimethacrylate, tetramethylolmethane trimethacrylate, tetramethylolmethane tetramethacrylate, pentaglycerol trimethacrylate, pentaerythritol trimethacrylate, pentaerythritol tetramethacrylate, glycerin trimethacrylate, dipentaerythritol trimethacrylate, dipe Taerythritol tetramethacrylate, Dipentaerythritol pentamethacrylate, Dipentaerythritol hexamethacrylate, Tris (methacryloyloxyethyl) isocyanurate Methacrylate compound; urethane acrylate compound or urethane methacrylate compound obtained by reaction of polyisocyanate having at least two isocyanate groups in the molecule and polyol compound having at least one acryloyloxy group or methacryloyloxy group and hydroxyl group, in the molecule At least two carboxylic acid halides and at least one acryloyl Examples thereof include polyester acrylate compounds and polyester methacrylate compounds obtained by a reaction with a polyol compound having an oxy group or a methacryloyloxy group and a hydroxyl group; and oligomers such as dimers and trimers of each of the above compounds. These compounds may be used alone or in combination of two or more.

  In addition to the polyfunctional (meth) acrylate, preferably 10.0% by weight or less of hydroxyethyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, based on the resin solid content during curing, At least one monofunctional (meth) selected from 2-hydroxypropyl (meth) acrylate, hydroxybutyl (meth) acrylate, 2-hydroxy-3-phenoxypropyl (meth) acrylate, glycidyl (meth) acrylate and the like An acrylate may be blended.

  In addition, a polymerizable oligomer can be added to the ultraviolet curable resin for the purpose of adjusting the hardness. Such oligomers include terminal (meth) acrylate polymethyl methacrylate, terminal styryl poly (meth) acrylate, terminal (meth) acrylate polystyrene, terminal (meth) acrylate polyethylene glycol, terminal (meth) acrylate acrylonitrile-styrene copolymer, Examples thereof include macromonomers such as terminal (meth) acrylate styrene-methyl (meth) acrylate copolymer. The content thereof is preferably 5.0 to 50.0% by weight with respect to the solid content at the time of curing of the composition.

In general, the refractive index of the ultraviolet curable resin is about 1.5, which is about the same as that of glass. However, when the refractive index of the resin used is low in comparison with the refractive index of the light-transmitting fine particles, TiO ₂ (refractive index; 2.3 to 2.7), Y ₂ O ₃ (refractive index; 1.87), La ₂ O ₃ (refractive index; 1), which are fine particles having a high refractive index, are used for the translucent resin. .95), ZrO ₂ (refractive index; 2.05), Al ₂ O ₃ (refractive index; 1.63), etc. are added to the extent that the diffusibility of the coating film can be maintained, and the refractive index is increased and adjusted. Can do.

  Such an ultraviolet curable resin may be used as a solution mixed with a solvent. The ultraviolet curable resin or the solution thereof may be a commercially available hard coat agent. Specific examples of commercially available hard coat agents include “NK Hard M101” (manufactured by Shin Nakamura Chemical Co., Ltd., urethane acrylate compound), “NK Ester A-TMM-3L” (manufactured by Shin Nakamura Chemical Co., Ltd., tetramethylol). Methane triacrylate), "NK ester A-9530" (manufactured by Shin-Nakamura Chemical Co., Ltd., dipentaerythritol hexaacrylate), "KAYARAD DPCA series" (manufactured by Nippon Kayaku Co., Ltd., derivatives of dipentaerythritol hexaacrylate compound) ), “Aronix M-8560” (manufactured by Toa Gosei Co., Ltd., polyester acrylate compound), “New Frontier TEICA” (manufactured by Daiichi Kogyo Seiyaku Co., Ltd., tris (acryloyloxyethyl) isocyanurate), “PPZ” ( Kyoeisha Chemical Co., Ltd., phosphazene-based metacrine Compound), and the like.

  Further, from the viewpoint of facilitating application, the ultraviolet curable resin is preferably diluted with an appropriate solvent. As the solvent, the same organic solvent as mentioned in the hard coat layer can be used. Similarly, the boiling point of the solvent is preferably in the range of 70 ° C to 200 ° C.

  The composition containing an ultraviolet curable resin may contain a polymerization initiator. A photopolymerization initiator is used as the polymerization initiator. As the photopolymerization initiator, the same compounds as those mentioned in the hard coat layer can be used.

  The usage-amount of a photoinitiator is 0.1 weight part or more per 100 weight part of ultraviolet curable resins. When the amount is less than 0.1 part by weight, the curing rate tends to be difficult to increase as compared with the case where no photopolymerization initiator is used. In addition, the upper limit of the usage-amount of a photoinitiator is about 10 weight part per 100 weight part of ultraviolet curable resin.

  The composition containing an ultraviolet curable resin may contain an antistatic agent. By containing an antistatic agent, an antiglare layer having antistatic performance and antistatic performance can be obtained. As the antistatic agent, the antistatic agents mentioned in the hard coat layer described above can be used.

  By dispersing the translucent fine particles in the ultraviolet curable resin composition obtained as described above, a desired coating solution for forming an antiglare layer can be obtained. There are no particular limitations on the timing and method of dispersing the translucent fine particles in the ultraviolet curable resin.

  The antiglare layer can be formed by applying the antiglare layer-forming coating solution on the acrylic resin film 25 and then drying. The coating can be performed by an ordinary method such as a micro gravure coating method, a roll coating method, a dipping coating method, a spin coating method, a die coating method, a cast transfer method, a flow coating method, or a spray coating method.

  Thereafter, the ultraviolet curable resin is cured by irradiating ultraviolet rays to obtain an antiglare layer. The intensity | strength of the ultraviolet-ray to irradiate, irradiation time, etc. are suitably selected according to the kind etc. of the curable compound to be used, the thickness of the layer containing a curable compound, etc. Ultraviolet rays may be irradiated in an inert gas atmosphere. In order to irradiate ultraviolet rays in a nitrogen atmosphere, for example, irradiation of activation energy rays may be performed in a container sealed with an inert gas, and nitrogen gas, argon gas, or the like can be used as the inert gas.

  The haze of the antiglare layer is in the range of 5 to 50%. The haze of the antiglare layer is measured by a method according to JIS K 7361. The thickness of the antiglare layer can be appropriately adjusted so that the haze of the antiglare layer falls within the range, but is preferably 2 μm to 20 μm. When the thickness of the antiglare layer is less than 2 μm, a sufficient antiglare effect cannot be obtained. Moreover, when it becomes thicker than 20 micrometers, there exists a tendency for it to become easy to break, or for a glare-proof layer to curl by hardening shrinkage of a glare-proof layer, and for productivity to fall. In general, the thickness of the antiglare layer is preferably 85% or more, more preferably 100% or more, based on the weight average particle diameter of the dispersed light-transmitting fine particles. When the thickness of the antiglare layer is less than 85% of the weight average particle diameter of the translucent fine particles, the haze becomes too large and the visibility tends to decrease.

  The antiglare layer may have a low reflection layer on the outermost surface thereof, that is, the uneven surface side. Even if there is no low reflection layer, it exhibits a sufficient antiglare function, but the antiglare property can be further improved by providing a low reflection layer on the outermost surface. As the low reflection layer, those described later can be applied.

[Antireflection layer / Low reflection layer]
The antireflection layer generally comprises a low refractive index layer which is also an antifouling layer, and at least one layer having a higher refractive index than that of the low refractive index layer (that is, a high refractive index layer or a medium refractive index layer), and an acrylic system. It is formed by being provided on the surface of the resin film 25.

  As a method of manufacturing a multilayer film in which transparent thin films of inorganic compounds (metal oxides, etc.) having different refractive indexes are laminated, chemical vapor deposition (CVD) method, physical vapor deposition (PVD) method, metal compound sol such as metal alkoxide / Examples thereof include a method of forming a thin film by forming a colloidal metal oxide particle film by a gel method and then post-processing (ultraviolet irradiation: JP-A-9-157855, plasma treatment: JP-A-2002-327310).

  On the other hand, various antireflection layers in which a thin film in which inorganic particles are dispersed in a matrix are laminated are proposed as antireflection layers with high productivity. In addition, an antireflection layer in which a fine uneven shape is formed on the surface of the uppermost layer of the antireflection layer by such application to impart antiglare properties has also been proposed.

The low reflection film is a layer formed of a low refractive index material having a refractive index lower than that of the acrylic resin film 25 serving as a base material. As such a low refractive index material, specifically, lithium fluoride (LiF), magnesium fluoride (MgF ₂ ), aluminum fluoride (AlF ₃ ), cryolite (3NaF · AlF ₃ or Na ₃ AlF ₆₎ ) And other inorganic low-reflective materials containing acrylic resin, epoxy resin, etc .; fluorine-based or silicone-based organic compounds, thermoplastic resins, thermosetting resins, UV-curable resins, etc. An organic low reflection material can be mentioned.

[Anti-fouling layer, etc.]
For the purpose of imparting properties such as antifouling properties, water resistance, chemical resistance, and slipping properties, a known silicone-based or fluorine-based antifouling agent, slipping agent, etc. are added to the resin composition forming the hard coat layer described above. It can also be added as appropriate. When these additives are added, it is preferably added in the range of 0.01 to 20% by mass, more preferably in the range of 0.05 to 10% by mass of the total solid content of the low n layer. Particularly preferably 0.1 to 5% by mass.

[Dust-proof layer / Antistatic layer]
For the purpose of imparting dust resistance and antistatic properties, a known cationic surfactant or polyoxyalkylene compound such as a dustproof agent or antistatic agent is added as appropriate to the resin composition forming the hard coat layer described above. You can also These dustproof agents and antistatic agents may contain the structural unit as part of their functions in the above-described silicone-based compounds and fluorine-based compounds. When adding these as additives, it is preferable to add in the range of 0.01 to 20% by mass of the total solid content of the low n layer, more preferably in the range of 0.05 to 10% by mass, especially Preferably it is 0.1-5 mass%.

(3) Polarizing film 21;
Subsequently, other layers constituting the polarizing plate 20 will be described. The polarizing film 21 is a member having a function of converting natural light into linearly polarized light. As the polarizing film 21, a film obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol resin film can be used. As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. As the polyvinyl acetate resin, in addition to polyvinyl acetate which is a homopolymer of vinyl acetate, polyvinyl acetate and Examples thereof include copolymers with other copolymerizable monomers. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, unsaturated sulfonic acids, and acrylamides having an ammonium group.

  The saponification degree of the polyvinyl alcohol resin is usually about 85 to 100 mol%, preferably 98 mol% or more. The polyvinyl alcohol resin may be modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, preferably about 1,500 to 5,000.

  A film obtained by forming such a polyvinyl alcohol resin is used as a raw film of the polarizing film 21. The method for forming a polyvinyl alcohol-based resin is not particularly limited, and can be formed by a known method. Although the thickness of a polyvinyl alcohol-type raw film is not specifically limited, For example, it is about 5-150 micrometers.

  The polarizing film 21 usually has a step of uniaxially stretching such a polyvinyl alcohol resin film, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol resin film with a dichroic dye, and a dichroic dye It is manufactured through a step of treating the adsorbed polyvinyl alcohol-based resin film with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution.

  Uniaxial stretching of the polyvinyl alcohol-based resin film can be performed before dyeing with the dichroic dye, simultaneously with dyeing, or after dyeing. When uniaxial stretching is performed after dyeing, this uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Of course, uniaxial stretching can also be performed in a plurality of stages shown here. For uniaxial stretching, a method of stretching uniaxially between rolls having different peripheral speeds, a method of stretching uniaxially using a hot roll, or the like can be adopted. The uniaxial stretching may be dry stretching in which stretching is performed in the air, or may be wet stretching in which a polyvinyl alcohol-based resin film is swollen using a solvent such as water. The draw ratio is usually about 3 to 8 times.

  The stretching direction of the polyvinyl alcohol-based resin film is a direction parallel to the longitudinal direction of the long polarizing film 21. For this reason, the absorption axis of the polarizing film 21 is a direction parallel to the stretching direction of the polyvinyl alcohol-based resin film, that is, the longitudinal direction of the long polarizing film 21.

  The polyvinyl alcohol resin film can be dyed with a dichroic dye by, for example, a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye. Specifically, iodine or a dichroic dye is used as the dichroic dye. In addition, it is preferable to perform the process which a polyvinyl alcohol-type resin film swells by immersing in water before a dyeing process.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this aqueous solution is usually about 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. It is. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C. Moreover, the immersion time (dyeing time) in this aqueous solution is usually about 20 to 1,800 seconds.

On the other hand, when a dichroic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye is usually employed. The content of the dichroic dye in this aqueous solution is usually about 1 × 10 ⁻⁴ to 10 parts by weight, preferably about 1 × 10 ⁻³ to 1 part by weight per 100 parts by weight of water. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dichroic dye solution used for dyeing is usually about 20 to 80 ° C. Moreover, the immersion time (dyeing time) in this aqueous solution is usually about 10 to 1,800 seconds.

  The boric acid treatment after dyeing with a dichroic dye can be performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution. The boric acid content in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, preferably about 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably contains potassium iodide. The content of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight, preferably about 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 60 to 1,200 seconds, preferably about 150 to 600 seconds, and more preferably about 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., more preferably 60 to 80 ° C.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment can be performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C., and the immersion time is usually about 1 to 120 seconds.

  After washing with water, a drying process is performed to obtain the polarizing film 21. The drying process can be performed using a hot air dryer or a far infrared heater. The temperature of a drying process is about 30-100 degreeC normally, Preferably it is 50-80 degreeC. The drying time is usually about 60 to 600 seconds, preferably 120 to 600 seconds.

  In this way, the polyvinyl alcohol-based resin film is subjected to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment, and the polarizing film 21 is obtained. The thickness of the polarizing film 21 can be about 2-40 micrometers, for example.

  The polarizing film 21 is stored in a rolled state. At the time of use, it is used by extending from a state wound in a roll shape into a long shape. The absorption axis of the polarizing film 21 is a direction parallel to the longitudinal direction of the long polarizing plate 20, that is, the stretching direction of the polyvinyl alcohol resin film.

(4) adhesive layer 28;
The inner resin film 23 and the acrylic resin film 25 are usually bonded to the polarizing film 21 via the adhesive layer 28. The adhesive forming the adhesive layer 28 provided on both surfaces of the polarizing film 21 may be the same or different.

  As the adhesive, an adhesive having an epoxy resin, urethane resin, cyanoacrylate resin, acrylamide resin, or the like as an adhesive component can be used. One of the adhesives preferably used is a solventless type adhesive. Solventless adhesives do not contain a significant amount of solvent, and are curable compounds (monomers or oligomers) that are reactively cured by heating or irradiation with active energy rays (for example, ultraviolet rays, visible light, electron beams, X-rays, etc.) The adhesive layer 28 is formed by curing the curable compound, and typically includes a curable compound that is reactively cured by heating or irradiation with active energy rays, and a polymerization initiator. In particular, when the inner resin film 23 and the acrylic resin film 25 are made of a polypropylene resin, the polypropylene resin film has a low moisture permeability, so that when water-based adhesive is used, water drainage is poor, and polarization is caused by moisture in the adhesive. The film 21 may be damaged or the polarization performance may be deteriorated. Therefore, when bonding such a resin film with low moisture permeability, a solventless adhesive is preferable.

  As an example of a preferable adhesive for forming the adhesive layer 28 from the viewpoint of rapid curing and productivity improvement of the first polarizing plate 20 associated therewith, an active energy ray-curable adhesive that is cured by irradiation with active energy rays Can be mentioned. As an example of such an active energy ray-curable adhesive, for example, a photo-curable adhesive that is cured by light energy such as ultraviolet light and visible light can be cited. As the photocurable adhesive, those that are cured by cationic polymerization are preferable from the viewpoint of reactivity, and in particular, the solventless epoxy adhesive that uses an epoxy compound as a curable compound includes the polarizing film 21 and the inner resin film. 23 and the acrylic resin film 25 are more preferable because of excellent adhesion.

  Although it does not restrict | limit especially as an epoxy compound which is a sclerosing | hardenable compound contained in the said solventless type epoxy adhesive, The thing hardened | cured by cationic polymerization is preferable. In particular, from the viewpoint of weather resistance and refractive index, it is more preferable to use an epoxy compound that does not contain an aromatic ring in the molecule. Examples of such epoxy compounds that do not contain an aromatic ring in the molecule include hydrides of aromatic epoxy compounds, alicyclic epoxy compounds, and aliphatic epoxy compounds. In addition, the epoxy compound that is a curable compound usually has two or more epoxy groups in the molecule.

  After the inner resin film 23 and the acrylic resin film 25 are bonded to the polarizing film 21 through the adhesive layer 28 made of an uncured epoxy adhesive, the active energy ray is irradiated or heated. Then, the adhesive layer 28 is cured, and the inner resin film 23 and the acrylic resin film 25 are fixed on the polarizing film 21. In the case of curing by irradiation with active energy rays, ultraviolet rays are preferably used. Specific examples of the ultraviolet light source include a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, a black light lamp, and a metal halide lamp. The irradiation intensity and irradiation amount of active energy rays such as ultraviolet rays are appropriately selected so as to sufficiently activate the cationic polymerization initiator and not adversely affect the cured film such as the adhesive layer 28 and the polarizing film 21. The In the case of curing by heating, it can be heated by a generally known method, and the temperature and time at that time sufficiently activate the cationic polymerization initiator, and the cured adhesive layer 28 And a film such as the polarizing film 21 are appropriately selected so as not to adversely affect the film.

  The thickness of the adhesive layer 28 made of an epoxy adhesive after curing, obtained as described above, is usually 50 μm or less, preferably 20 μm or less, more preferably 10 μm or less, and usually 1 μm or more.

  Further, from the viewpoint of thinning the adhesive layer 28, an aqueous adhesive, that is, an adhesive in which an adhesive component is dissolved in water or an adhesive component is dispersed in water can also be used as the adhesive. For example, an aqueous composition using a polyvinyl alcohol resin or a urethane resin as a main component can be mentioned as a preferred aqueous adhesive.

  A conventionally known method can be used as a method of laminating each film. For example, the polarizing film 21 and / or the film to be bonded to it by the casting method, Meyer bar coating method, gravure coating method, comma coater method, doctor blade method, die coating method, dip coating method, spraying method, etc. The method of apply | coating an adhesive agent to a surface and superimposing both is mentioned. The casting method is a method of spreading and spreading an adhesive on the surface of a film to be coated while moving the film in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between the two.

  In order to improve adhesiveness, the surface of each film may be appropriately subjected to surface activation treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment. Examples of the saponification treatment include a method of immersing in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide.

  The laminated body joined via the water-based adhesive is usually subjected to a drying treatment, and the adhesive layer 28 is dried and cured. The drying process can be performed, for example, by blowing hot air. A drying temperature is normally selected from the range of about 40-100 degreeC, Preferably it is 60-100 degreeC. The drying time is, for example, about 20 to 1,200 seconds. The thickness of the adhesive layer 28 after drying is usually about 0.001 to 5 μm, preferably 0.01 μm or more, preferably 2 μm or less, more preferably 1 μm or less. If the thickness of the adhesive layer 28 becomes too large, the appearance of the first polarizing plate 20 tends to be poor.

(5) Inner resin film 23;
The inner resin film 23 is a film that is bonded to the surface of the polarizing film 21, and films having various properties can be adopted depending on the characteristics required for a liquid crystal panel or a liquid crystal display device. As an example of the inner side resin film 23, when the polarizing plate 20 is used as an elliptically polarizing plate, a retardation layer provided with a quarter wavelength plate is mentioned, for example. Moreover, when the polarizing plate 20 is used as a linear polarizing plate, for example, a biaxial retardation film having an optical compensation function, a non-oriented film having a surface protection function, and the like can be given.

  The resin material which comprises the inner side resin film 23 is not specifically limited. Examples of such resin materials include (meth) acrylic resins such as methyl methacrylate resins ((meth) acrylic resins mean methacrylic resins or acrylic resins), olefin resins, poly Vinyl chloride resin, cellulose resin, styrene resin, acrylonitrile / butadiene / styrene copolymer resin, acrylonitrile / styrene copolymer resin, polyvinyl acetate resin, polyvinylidene chloride resin, polyamide resin, polyacetal resin Polycarbonate resin, modified polyphenylene ether resin, polyester resin (for example, polybutylene terephthalate resin, polyethylene terephthalate resin, etc.), polysulfone resin, polyethersulfone resin, polyarylate resin, polyamideimide resin, Polyimide resins, epoxy resins, and oxetane-based resin. These resins can contain additives as long as transparency and adhesiveness with the polarizing film 21 are not impaired.

  The resin material mentioned above can be made into the inner resin film 23 by forming a film by an arbitrary method and subjecting it to stretching treatment as necessary. Examples of the film forming method include an extrusion molding method from a molten resin, a solvent casting method in which a resin dissolved in an organic solvent is cast on a flat plate, and the solvent is removed to form a film.

  The obtained film may be used unstretched, but may be subjected to a stretching treatment as necessary. Examples of the stretching treatment include uniaxial stretching for stretching in the machine flow direction, biaxial stretching for stretching in a direction perpendicular to the machine flow direction in addition to uniaxial stretching, and oblique stretching for stretching in a direction oblique to the machine flow direction. . In the case of biaxial stretching, the order of stretching may be either sequential or simultaneous.

  The inner resin film 23 preferably has a Gurley bending resistance measured in accordance with JIS L 1096 of 350 mgf or less, more preferably 200 mgf or less, and even more preferably 150 mgf or less. Thus, since the rigidity of the polarizing plate 20 obtained is reduced by using the inner side resin film 23 with small bending resistance, the handleability at the time of bonding to a liquid crystal cell can be improved. In this specification, the Gurley bending resistance is a value measured according to JIS L 1096 as described above.

  The thickness of the inner resin film 23 is usually 20 to 200 μm, preferably 20 to 120 μm. When the thickness of the inner resin film 23 is less than 20 μm, the handling properties tend to be inferior, and even when the thickness exceeds 200 μm, the handling properties may be lowered due to the increased rigidity of the film.

  The resin material which comprises the inner side resin film 23 may use the resin material mentioned above independently, and may use it in combination of 2 or more types. Further, these resin materials can be used after any appropriate polymer modification. Examples of the polymer modification include modification such as copolymerization, cross-linking, molecular terminal modification, stereoregularity control, and mixing including a case involving reactions between different polymers.

(6) pressure-sensitive adhesive layer 27;
The pressure-sensitive adhesive layer 27 is used for bonding the polarizing plate 20 or the polarizing plate 20 cut into a predetermined shape from the polarizing plate 20 to a liquid crystal cell. Examples of the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer 27 include those having an acrylic polymer, silicone-based polymer, polyester, polyurethane, polyether or the like as a base polymer. Among them, acrylic pressure-sensitive adhesives based on acrylic polymers are excellent in optical transparency, maintain appropriate wettability and cohesive strength, and are also excellent in weather resistance and heat resistance. It is preferably used because it does not easily cause separation problems such as floating and peeling even under conditions.

  In the acrylic base polymer constituting the acrylic pressure-sensitive adhesive, an acrylic acid alkyl ester having an ester group having an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group, a butyl group, or a 2-ethylhexyl group; An acrylic copolymer with a functional group-containing (meth) acrylic monomer such as (meth) acrylic acid or 2-hydroxyethyl (meth) acrylate is preferably used. The pressure-sensitive adhesive layer 27 containing such an acrylic copolymer causes adhesive residue or the like on the glass substrate on the surface of the liquid crystal cell when it needs to be peeled off after being bonded to the liquid crystal cell. It can be peeled relatively easily without causing it. The acrylic copolymer used for the pressure-sensitive adhesive preferably has a glass transition temperature of 25 ° C. or lower, and more preferably 0 ° C. or lower. The acrylic copolymer usually has a weight average molecular weight of 100,000 or more.

  As the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer 27, a diffusion pressure-sensitive adhesive in which a light diffusing agent is dispersed can be used. The light diffusing agent is for imparting light diffusibility to the pressure-sensitive adhesive layer 27. The light diffusing agent may be fine particles having a refractive index different from that of the base polymer constituting the pressure-sensitive adhesive layer 27, and fine particles made of an inorganic compound or fine particles made of an organic compound (polymer) can be used. Since the base polymer constituting the pressure-sensitive adhesive layer 27 including the acrylic base polymer as described above often has a refractive index of around 1.4, the light diffusing agent has a refractive index of about 1-2. What is necessary is just to select suitably from things. The difference in refractive index between the base polymer constituting the pressure-sensitive adhesive layer 27 and the light diffusing agent is usually 0.01 or more, and from the viewpoint of ensuring the brightness and visibility of the applied liquid crystal display device, 0.01 or more. It is preferable that it is 0.5 or less. The fine particles used as the light diffusing agent are preferably spherical and those close to monodisperse, and fine particles having an average particle diameter of about 2 to 6 μm are preferably used.

  Examples of the fine particles made of an inorganic compound include aluminum oxide (refractive index 1.76) and silicon oxide (refractive index 1.45). Examples of the fine particles composed of an organic compound (polymer) include melamine resin beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), methyl methacrylate / styrene copolymer resin beads ( (Refractive index 1.50 to 1.59), polycarbonate beads (refractive index 1.55), polyethylene beads (refractive index 1.53), polystyrene beads (refractive index 1.6), polyvinyl chloride beads (refractive index 1. 46), silicone resin beads (refractive index 1.46), and the like.

  The amount of the light diffusing agent is appropriately determined in consideration of the haze value required for the pressure-sensitive adhesive layer 27 in which it is dispersed, the brightness of the liquid crystal display device to which it is applied, etc. The amount is about 3 to 30 parts by weight with respect to 100 parts by weight of the base polymer constituting the agent layer 27.

  The haze value measured according to JIS K 7361 of the pressure-sensitive adhesive layer 27 in which the light diffusing agent is dispersed is from the viewpoint of ensuring the brightness of the applied liquid crystal display device and making the display image less likely to bleed or blur. A range of 20 to 80% is preferable.

  Each component (base polymer, light diffusing agent, crosslinking agent, etc.) constituting the transparent pressure-sensitive adhesive or diffusion pressure-sensitive adhesive is dissolved in a suitable solvent such as ethyl acetate to form a pressure-sensitive adhesive composition. However, components that are not soluble in a solvent such as a light diffusing agent are dispersed. The pressure-sensitive adhesive layer 27 can be formed by applying this pressure-sensitive adhesive composition onto the inner resin film 23 and drying it.

  In order to remove static electricity charged in the polarizing plate 20, the pressure-sensitive adhesive layer 27 preferably has antistatic properties. In the polarizing plate 20, a separate film is laminated on the pressure-sensitive adhesive layer 27 as necessary. However, when the separate film is peeled off and bonded to a liquid crystal cell, it may be charged with static electricity. At this time, if the pressure-sensitive adhesive layer 27 has antistatic properties, the static electricity is quickly eliminated, and the display circuit of the liquid crystal cell is prevented from being broken and the liquid crystal molecules from being disturbed in alignment. .

  Examples of the method for imparting antistatic properties to the pressure-sensitive adhesive layer 27 include a method in which the pressure-sensitive adhesive composition contains metal fine particles, metal oxide fine particles, or fine particles coated with a metal, etc., electrolyte salt and organopolysiloxane And a method of incorporating an organic salt-based antistatic agent. The required antistatic holding time is at least about 6 months from the viewpoint of production, distribution, and storage period of a general polarizing plate 20.

  The adhesive layer 27 may pass active energy rays in order to cure the adhesive layer 28. Therefore, it is preferable to have a high transmittance in the corresponding spectral region of the active energy ray. In addition, it is preferable that various characteristics as an adhesive do not change by irradiation of an active energy ray.

  For example, the pressure-sensitive adhesive layer 27 is aged for about 3 to 20 days in an environment of a temperature of 23 ° C. and a relative humidity of 65%, and after sufficiently proceeding with the reaction of the crosslinking agent, is used for bonding to a liquid crystal cell. .

  The thickness of the pressure-sensitive adhesive layer 27 is appropriately determined according to the adhesive force and the like, but is usually about 1 to 40 μm. In order to obtain a thin polarizing plate 20 without impairing properties such as workability and durability, the thickness of the pressure-sensitive adhesive layer 27 is preferably about 3 to 25 μm. In addition, when the pressure-sensitive adhesive layer 27 in which the light diffusing agent is dispersed is used, the brightness when the liquid crystal display device is viewed from the front or obliquely is set by setting the thickness of the pressure-sensitive adhesive layer 27 within this range. It is possible to keep the display image from blurring and blurring.

<Liquid crystal panel and liquid crystal display device>
Next, a liquid crystal panel and a liquid crystal display device using the acrylic resin film 25 and the polarizing plate 20 using the acrylic resin film 25 will be described. FIG. 4 is a schematic cross-sectional view showing an example of a basic layer configuration of the liquid crystal panel 2 using the polarizing plate 20 and the liquid crystal display device 1 to which the liquid crystal panel 2 is applied. As shown in this figure, the polarizing plate 20 is bonded to the liquid crystal cell 40 and used as a component of the liquid crystal panel 2. The liquid crystal panel 2 is a constituent member of the liquid crystal display device 1. The liquid crystal panel 2 includes a liquid crystal cell 40, a polarizing plate 20 bonded to the viewing side of the liquid crystal cell 40, and a polarizing plate 30 bonded to the back side of the liquid crystal cell 40. The liquid crystal display device 1 includes a liquid crystal panel 2, a backlight 10, and a light diffusion plate 50. In the liquid crystal display device 1, the liquid crystal panel 2 is disposed such that the polarizing plate 30 is on the backlight 10 side. The polarizing plate 20 and the polarizing plate 30 are each bonded to the liquid crystal cell 40 via an adhesive layer. Here, the back side means the backlight 10 side when the liquid crystal panel 2 is mounted on the liquid crystal display device 1. The viewing side means the side opposite to the backlight 10 when the liquid crystal panel 2 is mounted on the liquid crystal display device 1.

  The liquid crystal cell 40 is an element that displays an image by electrically controlling a cell in which a liquid crystal material is sealed between glass substrates. More specifically, the liquid crystal cell 40 has a back surface polarized by the polarizing plate 20 disposed on the back side of the liquid crystal cell 40 by changing the molecular orientation of the liquid crystal material by electrical control from a display control unit (not shown). An image is displayed by changing the polarization state of the light of the light 10 and controlling the amount of light transmitted through the polarizing plate 30 disposed on the viewing side of the liquid crystal cell 40. The mode of the liquid crystal cell 40 is not particularly limited. For example, a VA mode, an IPS mode, a TN mode, an STN mode, an OCB mode, an ASM mode, or the like can be used.

  The liquid crystal panel 2 and the liquid crystal display device 1 can be manufactured by a known method. As a manufacturing method of the liquid crystal panel 2, the long polarizing plate 20 and the polarizing plate 30 wound in a roll shape can be cut into pieces and bonded to the liquid crystal cell 40.

  The backlight 10 is a device for illuminating the liquid crystal cell 40. Examples of the type of the backlight 10 include an edge light type and a direct type. The edge-light type backlight 10 irradiates light to the liquid crystal cell 40 through a light guide plate from a light source such as a cold cathode tube or an LED arranged on a side surface. In the direct type backlight 10, a light source is disposed on the back side of the liquid crystal cell 40 to irradiate the liquid crystal cell 40 with light. As the type of the backlight 10, a backlight according to the application of the liquid crystal display device 1 can be appropriately adopted.

  The light diffusing plate 50 is an optical member having a function of diffusing light from the backlight 10, for example, a material in which particles as a light diffusing agent are dispersed in a thermoplastic resin to impart light diffusibility, thermoplasticity The surface of the resin film may be uneven to provide light diffusibility, or the resin film may be provided with a coating layer of a resin composition in which particles are dispersed on the surface of the thermoplastic resin film. . The thickness can be about 0.1-5 mm.

  Between the light diffusing plate 50 and the liquid crystal panel 2, a sheet or film exhibiting other optical functionality such as a brightness enhancement sheet (a reflective polarizing film (such as “DBEF”)) or a light diffusing sheet is disposed. You can also. Two or more sheets or films exhibiting other optical functionalities can be arranged as needed.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited by these examples. In the following examples, the part representing the amount used is based on weight unless otherwise specified.

[Example 1]
(A) Production of acrylic resin film;
(Acrylic resin and acrylic elastic polymer particles)
As the acrylic resin, a copolymer having a weight ratio of methyl methacrylate / methyl acrylate of 96/4 was used. Further, as the elastic rubber particles, acrylic elastic polymer particles having a three-layer structure including an innermost layer, an intermediate layer, and an outermost layer were used. In the acrylic elastic polymer particles, the innermost layer is a hard polymer obtained by polymerizing methyl methacrylate with a small amount of allyl methacrylate, the intermediate layer is mainly composed of butyl acrylate, styrene and a small amount of Soft elastic body polymerized using allyl methacrylate, outermost layer is made of a hard polymer polymerized with a small amount of ethyl acrylate in methyl methacrylate, and the average particle size up to the elastic body that is the intermediate layer The diameter is 240 nm.

(Preparation of acrylic resin film)
While melting and kneading a pellet in which the above acrylic resin and the above acrylic elastic polymer particles are blended in a weight ratio of the former / the latter = 70/30 with a twin screw extruder, did. The pellets were put into a 65 mmφ single screw extruder, extruded through a T die having a set temperature of 275 ° C., and both sides of the extruded film-like molten resin were polished rolls (cooling rolls) having mirror surfaces set at 45 ° C. Roll) and a metal elastic roll (elastic roll) having a high elastic modulus whose surface is formed of a metal material and filled with a fluid, and cooled to prepare an acrylic resin film.

(B) preparation of an adhesive;
Trade name “Epicoat (registered trademark) YX8000” (diglycidyl ether of nuclear hydrogenated bisphenol A, having an epoxy equivalent of about 205 g / equivalent), which is a hydrogenated epoxy resin manufactured by Japan Epoxy Resin Co., Ltd. 10 Part, Nippon Soda Co., Ltd. product photosensitizer “CS7001” 1.0 part was mixed and defoamed to prepare an adhesive made of an ultraviolet curable resin composition containing an epoxy resin. .

(C) Preparation of cyclic olefin resin film (COP);
“ZB · 55124” obtained from Nippon Zeon Co., Ltd. was used as a retardation film made of a cyclic olefin (COP) resin.

(D) sample preparation;
In order to evaluate the adhesiveness of the acrylic resin film, a sample for a T-type peel test was prepared. A test sample having a layer structure shown in FIG. 5 was used. The sample has a layer structure in which a film (COP) made of a cyclic olefin polymer resin (COP), an adhesive layer, a polarizing film made of polyvinyl alcohol (PVA), an adhesive layer, and an acrylic resin film (PMMA) are sequentially laminated. have.

  First, an acrylic resin film (PMMA), a cyclic olefin resin film (COP), and a polarizing film (PVA) were cut into 20 cm (machine flow direction: MD standard) × 15 cm (perpendicular to MD: TD standard). . Subsequently, a corona treatment was applied to the bonding surface of the acrylic resin film (PMMA) and the cyclic olefin polymer resin (COP). The corona treatment was performed twice using CT-212 (manufactured by Kasuga Denki Co., Ltd.) at 280 W × 10 m × 2.

Of the acrylic resin film, the grounding side (rough surface side) with the elastic roll was used as the adhesive surface with the polarizing film, and an adhesive was applied and adhered. The adhesive was cured by UV irradiation. The UV irradiation conditions are as follows: UVA is 271 mJ / cm ² (213 mW / cm ² ), UVB is 213 mJ / cm ² (163 mW / cm ² ), UVC is 22 mJ / cm ² (18 mW / cm ² ), and UVV is 17 mJ / cm ^2. (13 mW / cm ² ). After bonding, the film was cured for one day, and a peel test with a T-type peel was performed.

(F) Evaluation of adhesive strength;
The sample obtained above was subjected to a T-type peel test to evaluate the adhesive force between the acrylic resin film (PMMA) and the polarizing film (PVA). In the T-peel test, the film was pulled in the direction of 180 ° indicated by the arrow in FIG. 5, and the peeling force when the acrylic resin film and the polarizing film were peeled was measured. AGS-50NX (manufactured by Shimadzu Corporation) was used for measuring the peeling force. As the peel force value, three samples described above were prepared (N number = 3), and the average value of each peel force was adopted. Peeling between the acrylic resin film and the polarizing film occurs either between the acrylic resin film and the adhesive layer, or between the polarizing film and the adhesive layer. The peeling force when peeling occurred between the acrylic resin film and the adhesive layer was employed. The results are shown in Table 1. Note that “ND” in the table indicates that the peeling force could not be measured because no peeling occurred at the interface between the acrylic resin film and the adhesive layer.

[Comparative Example 1]
In Comparative Example 1, the grounding side (smooth surface side) with the cooling roll in the acrylic resin film was used as the adhesive surface with the polarizing film. Other conditions are the same as in the first embodiment. The same T-type peel test as the above-described adhesive strength evaluation method was performed, and the peel strength was measured. The number of samples is three (N number = 3), and the evaluation method is the same as in the first embodiment. The results are shown in Table 1.

Table 1 shows the measurement results of the peeling force of each sample of Example 1 and Comparative Example 1. FIG. 6 is a graph showing the average value. From this table and figure, in the case of bonding to the polarizing film on the rough surface side of the example of Example 1, that is, the acrylic resin film, the average value of the peeling force is 1.19, and the polarizing film is bonded to the smooth surface side. Compared to the case of Comparative Example 1, it was found that the peel force (that is, the adhesive force) was nearly 30% higher. From this, it was found that the adhesive force is higher when the rough surface is adhered to the polarizing film than the smooth surface of the acrylic resin film.

(G) Observation of acrylic resin film surface;
Next, the surface of the acrylic resin film of Example 1 was observed with a scanning probe microscope. SPM-9500 (manufactured by Shimadzu Corporation) was used as a scanning probe microscope. FIG. 7 shows micrographs of the surface of the acrylic resin film, where (a) is a rough surface and (b) is a smooth surface. FIG. 8 is a photomicrograph after corona treatment on the surface of the acrylic resin film, (a) is a rough surface and (b) is a smooth surface. In these photographs, the large white circles indicate the protrusions from which the elastic rubber particles protrude from the film surface.

  As shown in these figures, many irregular shapes in which the rubber elastic particles protrude from the film surface are observed on the rough surface side before and after the corona treatment (FIG. 7) and after the corona treatment (FIG. 8). On the other hand, on the smooth surface side, it can be seen that the uneven shape of the rubber elastic particles is smaller than that on the rough surface side, and the surface is almost smooth. From this, it was found that the surface grounded to the highly rigid cooling roll side is a smooth surface with few surface irregularities, which is suitable for adhesion to the polarizing film. On the other hand, the surface grounded to the elastic roll side, which has higher elasticity than the cooling roll, is a rough surface with many irregularities on the surface, which is found to be suitable for forming a functional layer.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device, 2 Liquid crystal panel, 10 Backlight, 12 Cooling roll (1st roll), 13 Elastic roll (2nd roll), 19 Winding roll, 20 Polarizing plate, 21 Polarizing film, 23 Inner resin film , 25 Acrylic resin film, 25a Smooth surface, 25b Rough surface, 26 Functional layer, 27 Adhesive layer, 28 Adhesive layer, 30 Polarizer, 40 Liquid crystal cell, 50 Light diffusion plate, R1 Smooth surface region, R2 Rough surface area

Claims (3)

A sheet-like acrylic resin film comprising an acrylic resin composition,
External haze value is 5% or less,
Of the one surface and the surface opposite to the one surface, the surface on the opposite side is a rough surface having a larger arithmetic average roughness than the one surface,
The acrylic resin film, wherein a difference in arithmetic mean roughness between the one surface and the opposite surface is 5 to 100 nm. A polarizing plate comprising the acrylic resin film according to claim 1 and a polarizing film,
The polarizing plate, wherein the polarizing film is laminated on the opposite surface through an adhesive layer.   The polarizing plate according to claim 2, wherein the one surface has a functional layer on the surface.

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