JP5884264B2 - Film with surface protection film, polarizing plate and method for producing the same - Google Patents

Description

  The present invention relates to a film with a surface protection film in which a surface protection film is bonded to a base film. The present invention also relates to a polarizing plate in which the film with a surface protective film is laminated on a polarizing film as a protective film and a method for producing the same.

  2. Description of the Related Art In recent years, liquid crystal display devices that consume less power, operate at a low voltage, and are light and thin have been widely used for information display devices such as mobile phones, portable information terminals, computer monitors, and televisions. Such an information display device is required to have reliability in a harsh environment depending on the application. For example, a liquid crystal display device for a car navigation system may have a very high temperature and humidity in the vehicle in which the liquid crystal display device is placed, and the required temperature and humidity conditions compared to a monitor for a normal television or personal computer. Is severe. In a liquid crystal display device, a polarizing plate is used to enable display. In a liquid crystal display device that requires such severe temperature and / or humidity conditions, the polarizing plate constituting the polarizing plate is also used. What has high durability is calculated | required.

  A polarizing plate usually has a structure in which a transparent protective film is laminated on both sides or one side of a polarizing film made of a polyvinyl alcohol-based resin in which a dichroic dye is adsorbed and oriented. Conventionally, triacetyl cellulose has been widely used for this protective film, and has been adhered to the polarizing film through an adhesive made of an aqueous solution of a polyvinyl alcohol resin. However, a polarizing plate on which a protective film made of triacetylcellulose is laminated has a high moisture permeability of triacetylcellulose. The polarizing film may peel off.

  So far, attempts have been made to use an acrylic resin film having a lower moisture permeability than the triacetyl cellulose film as a protective film for the polarizing plate. For example, in Japanese Patent Application Laid-Open No. 2007-25008 (Patent Document 1), a thermoplastic resin layer is provided on both surfaces of an acrylic resin layer having a thickness of 40 μm or less so as to be peelable from the acrylic resin layer. A polarizing film formed from a polyvinyl alcohol-based resin by forming a film, peeling off at least one of the thermoplastic resin layer from the optical film to form a protective film for the polarizing plate, and the acrylic resin layer side of the protective film. It is described that they are bonded to form a polarizing plate. Specifically, in this document, an optical film having a three-layer structure of polyethylene terephthalate / polymethyl methacrylate / polyethylene terephthalate or a three-layer of polycarbonate / polymethyl methacrylate / polycarbonate is obtained by co-extrusion using three extruders. An optical film having a structure is produced.

  JP 2007-41563 A (Patent Document 2) discloses that an optical film is formed by laminating a protective film mainly composed of an acrylic resin, a polyethyleneimine layer, and a polyvinyl alcohol resin layer in this order. In addition, it describes that the optical film is bonded to a polarizing film formed from a polyvinyl alcohol resin to form a polarizing plate. Furthermore, in JP 2007-52404 A (Patent Document 3), a polarizing film formed from a polyvinyl alcohol-based resin, an adhesive layer, a metal salt layer, and a protective film composed of an acrylic resin are stacked in this order to be polarized. It is described as a board.

  On the other hand, in order to adhere a resin film having low moisture permeability, such as an acrylic resin film, to a polyvinyl alcohol polarizing film, JP 2004-245925 A (Patent Document 4) and JP 2010-209126 A (Patent Document). In 5), it is proposed to use a curable composition containing an epoxy compound as a main component.

  As in Patent Documents 1 to 3, it is expected that the moisture resistance of the polarizing plate is improved by using an acrylic resin film having a low moisture permeability as a protective film for the polarizing plate. In addition, instead of an adhesive made of an aqueous solution of a polyvinyl alcohol-based resin, an adhesive made of a curable composition containing an epoxy compound is used for laminating an acrylic resin film and a polyvinyl alcohol-based polarizing film. It is expected to improve the heat resistance of the plate.

  However, it is known that acrylic resin films have poor toughness and are easily broken. And when manufacturing a polarizing plate using an acrylic resin film as a protective film, if the acrylic resin film breaks, the part must be removed as a defective product in the first place, and the broken pieces may contaminate the manufacturing process. there were.

In JP 2008-213401 (Patent Document 6), the mechanical extrusion direction (MD) of an acrylic resin film produced by melt extrusion using the ease of cracking of such an acrylic resin film. By reducing the difference between the shock absorption energy in the MD and the shock absorption energy in the direction perpendicular to the MD (TD), it is possible to easily remove the unnecessary part by rupturing even if it is bent by MD or TD. Has been proposed. That is, since the acrylic resin film produced by melt extrusion is oriented in the extrusion direction, the TD is more difficult to crack than the MD. In this document, the Charpy impact test of the test piece with the MD in the length direction is used. It has been proposed that the measured value of impact absorption energy by (in this case, it will break at TD) be 50 to 150 kJ / m ² . Specifically, an acrylic resin containing an appropriate amount of acrylic rubber particles having an appropriate particle size is melt-extruded to form a film, or an acrylic resin containing an appropriate amount of acrylic rubber particles having an appropriate particle size. By using a three-layer structure in which the resin is a surface layer and the amount of rubber particles is less than that, or an acrylic resin containing no rubber particles is an intermediate layer, the impact absorption energy of TD is 50 to 150 kJ as described above. An acrylic resin film is realized that falls within the range of / m ² , and the impact absorption energy of MD is the same as or slightly smaller than TD within that range.

However, in reality, an acrylic resin film having a shock absorption energy value of less than 50 kJ / m ² in either MD or TD in the Charpy impact test may be used as a protective film for the polarizing plate. In addition, the surface-treated resin film may be used as a protective film for the polarizing plate, but in the case of the resin film that has been surface-treated in this way, particularly in the case of an acrylic resin film that has been surface-treated. Therefore, cracking of the protective film at the time of bonding to a polarizing film has been a major issue.

JP 2007-25008 A JP 2007-41563 A JP 2007-52404 A JP 2004-245925 A JP 2010-209126 A JP 2008-213401 A

  The present invention has been made in view of the above circumstances, and its purpose is that the impact absorption energy value by the Charpy impact test itself is small, and it is applied to other films such as a polarizing film. When bonding, even if it is a base film that is easy to break, it is hard to break by pasting a surface protection film on it, so that it can be stably pasted to other films including polarizing films Is to provide an improved film. Another object of the present invention is to provide a film capable of suppressing scattering of fragments even if a base film is cracked.

  Another object of the present invention is to provide a polarizing plate that ensures production stability by using a protective film that is difficult to break and that does not scatter even if cracked, and further provides an advantageous manufacturing method thereof. There is to do.

The present inventors have found that by bonding a surface protective film to a base film having a shock absorption energy value of less than 50 kJ / m ² by a Charpy impact test, it is extremely difficult to break in the bonded state. Based on this finding, various studies were further made to complete the present invention.

That is, according to the present invention, the surface protection film is bonded to the base film having a shock absorption energy value of less than 50 kJ / m ² according to the Charpy impact test, and the impact absorption by the Charpy impact test in the bonded state is achieved. A film with a surface protection film having an energy value of 50 kJ / m ² or more is provided.

  In this film with a surface protective film, in one preferred embodiment, the base film is made of an acrylic resin. In another preferred embodiment, the base film is subjected to a surface treatment on one side, and the surface protection film is bonded to the surface-treated surface. When surface treatment is applied to the acrylic resin film, such a film is more easily broken, and therefore, the embodiment in which the above-mentioned surface protection film is bonded to the surface-treated surface is particularly effective.

  In these films with a surface protective film, this surface protective film has a pressure-sensitive adhesive layer on one side of the polyester-based resin film, and is preferably bonded to the base film on the pressure-sensitive adhesive layer side. . In particular, the surface protective film has an adhesion force of 0.03 N / 25 mm or more and 0.15 N / 25 mm or less to the base film to prevent the base film from cracking, and the base film side is the other side. It is advantageous from the viewpoint that the surface protective film can be easily peeled off from the base film after several steps after being applied to the layer, for example, a polarizing film.

  In addition, according to the present invention, there is also provided a polarizing plate with a surface protective film in which any of the above-described films with a surface protective film is bonded to the polarizing film on the base film side.

Furthermore, according to the present invention, there is also provided a method for producing a polarizing plate by laminating a base film on a polarizing film that is uniaxially stretched and has an absorption axis in the direction of the uniaxial stretching. The film itself has an impact absorption energy value of less than 50 kJ / m ² according to the Charpy impact test. The surface protective film is bonded to the base film, and the impact is determined by the Charpy impact test in the bonded state. A film with a surface protective film having an absorption energy value of 50 kJ / m ² or more is prepared, and then the base film side of the film with the surface protective film is bonded to the polarizing film.

  The film with the surface protection film of the present invention is brittle and easily broken by the base film itself constituting the film, but it is difficult to break by pasting the surface protection film on it, and other layers such as a polarizing film It is possible to improve the production stability when pasting together.

  Further, the polarizing plate with a surface protective film of the present invention is one in which the film with the surface protective film is bonded to the polarizing film on the base film side, so that the crack of the base film is effectively prevented. . Furthermore, according to the method of the present invention, such a polarizing plate with a surface protective film can be produced industrially advantageously with high production stability.

It is a cross-sectional schematic diagram which shows the preferable form of the film with a surface protection film which concerns on this invention. It is a cross-sectional schematic diagram which shows the preferable form of the polarizing plate with a surface protection film which concerns on this invention.

  Hereinafter, the present invention will be described in detail. In the present invention, as shown in a schematic cross-sectional view in FIG. 1, a surface protection film 14 is bonded to the base film 12 to obtain a film 10 with a surface protection film. This base film 12 is suitably used as a protective film for a polarizing plate.

[Base film]
The resin material which comprises the base film 12 will not be specifically limited if it is translucent. Examples of such resin materials include acrylic resins, polyolefin resins, polyvinyl chloride resins, cellulose resins, polystyrene resins, acrylonitrile / butadiene / styrene copolymer resins, typically methyl methacrylate resins. , 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) And polyethylene terephthalate resin), polysulfone resin, polyethersulfone resin, polyarylate resin, polyamideimide resin, polyimide resin, epoxy resin, and oxetane resin. These resins can contain additives as long as they do not impair transparency and adhesiveness with a polarizing film. In particular, since an acrylic resin film formed using an acrylic resin has low moisture permeability, it is excellent in moisture and heat resistance and is expected to be superior in use as a protective film for a polarizing film.

<Acrylic resin film>
The acrylic resin is usually a polymer mainly composed of alkyl methacrylate. Specifically, a homopolymer of alkyl methacrylate or a copolymer using two or more kinds of alkyl methacrylate may be used, or 50 wt% or more of alkyl methacrylate and 50 wt% of monomers other than alkyl methacrylate. % Or less copolymer. 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, but a monofunctional monomer is particularly preferably used. Examples thereof include alkyl acrylates such as methyl acrylate and ethyl acrylate, styrene monomers such as styrene and alkyl styrene, and unsaturated nitriles such as acrylonitrile and methacrylonitrile. When using an alkyl acrylate as a copolymerization component, the alkyl group usually has about 1 to 8 carbon atoms. The monomer composition of the acrylic resin 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 amount of the whole monomer. Further, it is preferably 99% by weight or less.

  The acrylic resin preferably does not have a cyclic structure such as a glutarimide derivative, a glutaric anhydride derivative, or a lactone ring structure. An acrylic resin having a cyclic structure such as a glutarimide derivative, a glutaric anhydride derivative, or a lactone ring structure tends to make it difficult to obtain sufficient mechanical strength and wet heat resistance as an optical film. In other words, in this acrylic resin, the monomer consists essentially of alkyl methacrylate, or the alkyl methacrylate accounts for 70% by weight or more, preferably 90% by weight or more of the monomer composition, It is preferably a copolymer of only a monomer selected from alkyl acrylate, a styrene monomer and an unsaturated nitrile.

  It is preferable to add rubber elastic particles to the acrylic resin in order to increase the film forming property. The rubber elastic particles used for this purpose are particles including a layer exhibiting rubber elasticity. The rubber elastic particles may be particles composed only of a layer exhibiting rubber elasticity, or may be particles having a multilayer structure having other layers together with a layer exhibiting rubber elasticity. Examples of the rubber elastic body include an olefin elastic polymer, a diene elastic polymer, a styrene-diene elastic copolymer, an acrylic elastic polymer, and the like. Among these, an acrylic elastic polymer is preferably used from the viewpoints of the surface hardness, light resistance, and transparency of the base film.

  The acrylic elastic polymer can be composed of a polymer mainly composed of alkyl acrylate. This may be a homopolymer of alkyl acrylate or a copolymer of 50% by weight or more of alkyl acrylate and 50% by weight or less of other monomers. As the alkyl acrylate, those having 4 to 8 carbon atoms in the alkyl group are usually used. Examples of copolymerization of monomers other than alkyl acrylate include alkyl methacrylates such as methyl methacrylate and ethyl methacrylate, styrene monomers such as styrene and alkylstyrene, acrylonitrile and methacrylo Monofunctional monomers such as unsaturated nitriles such as nitriles, alkenyl esters of unsaturated carboxylic acids such as allyl (meth) acrylate and methallyl (meth) acrylate, and 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 particles containing the acrylic elastic polymer are preferably multi-layered particles having an acrylic elastic polymer layer. Specifically, a two-layer structure having a hard polymer layer mainly composed of alkyl methacrylate on the outside of the acrylic elastic body, or a hard body mainly composed of alkyl methacrylate inside the acrylic elastic body. The thing of the 3 layer structure which has a polymer layer is mentioned. An example of the monomer composition in the polymer mainly composed of alkyl methacrylate constituting the hard polymer layer formed on the outside or inside of the acrylic elastic body is the methacrylic acid mentioned above as an example of the acrylic resin. This is the same as the monomer composition example of the polymer mainly composed of alkyl, and a monomer composition mainly composed of methyl methacrylate is preferably used. 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.

  The rubber elastic body particles preferably have an average particle diameter of the rubber elastic body layer contained therein in the range of 10 to 300 nm. Thereby, when it bonds to a polarizing film using an adhesive agent, the protective film which cannot peel easily from an adhesive bond layer can be obtained. The average particle diameter of the rubber elastic particles is more preferably 50 nm or more, and more preferably 250 nm or less.

  The average particle diameter of the rubber elastic particles containing the acrylic elastic polymer is measured as follows. That is, when such rubber elastic particles are mixed with an acrylic resin to form a film and the cross section thereof is dyed with an aqueous solution of ruthenium oxide, only the rubber elastic layer is colored and observed in a substantially circular shape. Acrylic resin is not dyed. Therefore, from the cross section of the film dyed in this way, a thin piece is prepared using a microtome or the like, and this is observed with an electron microscope. And after extracting 100 dye | stained rubber elastic body particles at random and calculating each particle diameter, let the number average value be an average particle diameter. In order to measure by such a method, the average particle diameter of the obtained rubber elastic body becomes a number average particle diameter.

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

  Such rubber elastic particles are preferably blended in a proportion of 25 to 45% by weight based on the total amount with the above-described transparent acrylic resin. By blending rubber elastic particles in this proportion, the film-forming property is improved, the impact resistance of the resulting base film is increased, and even the slight unevenness is formed on the surface of the film, so it is slippery. The effect which raises is expressed.

  A predetermined amount of the elastic rubber particles can be blended with the acrylic resin, and a small amount of lubricant can be blended to form a base film. When the lubricant is blended, it is possible to prevent tight tightening when the acrylic resin film is wound in a roll shape, thereby improving the package appearance in the wound state. Any lubricant may be used as long as it has a function of improving the slipperiness of the acrylic resin film surface. Examples of compounds having such functions include stearic acid compounds, acrylic compounds, ester compounds, and the like. Of these, stearic acid compounds are preferably used as lubricants.

  Examples of stearic acid compounds used as lubricants include stearic acid itself, as well as stearic acid esters such as methyl stearate, ethyl stearate, and monoglyceride stearate; stearic acid amides; sodium stearate, calcium stearate, stearic acid Metal stearates such as zinc, lithium stearate, magnesium stearate; 12-hydroxystearic acid, sodium 12-hydroxystearate, zinc 12-hydroxystearate, calcium 12-hydroxystearate, lithium 12-hydroxystearate Examples thereof include 12-hydroxystearic acid such as magnesium 12-hydroxystearate and a metal salt thereof. Of these, stearic acid is preferably used.

  The blending amount of the lubricant is preferably in the range of 0.01 to 0.09 parts by weight with respect to 100 parts by weight of the total of the acrylic resin and the rubber elastic body particles. A more preferable blending amount of the lubricant is 0.03 parts by weight or more and 0.07 parts by weight or less based on 100 parts by weight of the total of the acrylic resin and the rubber elastic body particles. When the blending amount of the lubricant is small, it is difficult to obtain a sufficient slip property on the film surface, and winding tightening is likely to occur. On the other hand, if the amount is too large, the lubricant may bleed out from the film or the transparency of the film may be reduced.

  The acrylic resin in which the rubber elastic particles and the lubricant are blended only needs to finally have the composition described so far, and the production method thereof is arbitrary. For example, first, rubber elastic particles are manufactured, and in the presence of this, the monomer that is the raw material of the acrylic resin is polymerized to form a base acrylic resin, and then the rubber elastic particles are blended into the acrylic resin. A method of adding a predetermined amount of a lubricant to the composition, a method of mixing rubber elastic particles and an acrylic resin in a predetermined ratio, adding a predetermined amount of the lubricant to this, and mixing by melt kneading, etc. Can be mentioned.

  The acrylic resin suitably used for the base film 12 is an optical brightener, a dispersant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an infrared absorber, an antistatic agent, and an antioxidant as necessary. Various additives such as may be contained.

  The ultraviolet absorber is a compound that absorbs ultraviolet rays having a wavelength of 400 nm or less. When the base film is used as a protective film for a polyvinyl alcohol polarizing film, an effect of improving the durability of the polarizing plate in which the protective film is bonded to the polarizing film is obtained by blending an ultraviolet absorber. As the ultraviolet absorber, known ones such as a benzophenone ultraviolet absorber, a benzotriazole ultraviolet absorber, and an acrylonitrile ultraviolet absorber can be used. Specific examples include 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 Examples include '-dihydroxy-4,4'-dimethoxybenzophenone and 2,2', 4,4'-tetrahydroxybenzophenone. Among these, 2,2′-methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- (2H-benzotriazol-2-yl) phenol] is one of preferable ultraviolet absorbers. One. The blending amount of the ultraviolet absorber can be selected in such a range that the transmittance of the base film at a wavelength of 370 nm or less is preferably 10% or less, more preferably 5% or less, and further preferably 2% or less. As a method of containing the ultraviolet absorber, the ultraviolet absorber is premixed in an acrylic resin and pelletized, and this is formed into a film by melt extrusion or the like. Any method can be used.

  An infrared absorber is a compound that absorbs infrared rays having a wavelength of 800 nm or more. For example, nitroso compounds, metal complex salts thereof, cyanine compounds, squarylium compounds, thiol nickel complex compounds, phthalocyanine compounds, naphthalocyanine compounds, triarylmethane compounds, imonium compounds, diimonium compounds, naphthoquinone compounds, List anthraquinone compounds, amino compounds, aminium salt compounds, carbon black, indium tin oxide, antimony tin oxide, oxides, carbides or borides of metals belonging to groups 4A, 5A or 6A of the periodic table Can do. These infrared absorbers are preferably selected so that they can absorb the entire infrared rays (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 compounding quantity of an infrared absorber can be suitably adjusted, for example so that the light transmittance in wavelength 800nm or more of a base film may be 10% or less.

<Multilayer structure of base film>
The base film 12 can also have a multilayer structure as appropriate. For example, a layer formed from a composition in which a predetermined amount of rubber elastic particles are blended in an acrylic resin, and a small amount of lubricant is blended if necessary, and a multilayer structure with a layer formed from another composition can do. In this case, the layer that may exist other than the acrylic resin layer in which the rubber elastic particles are blended is not particularly limited in composition, for example, an acrylic resin layer that does not contain rubber elastic particles. Alternatively, it may be a layer made of an acrylic resin in which the content of the rubber elastic body particles and the average particle diameter of the elastic body in the rubber elastic body particles are different. Typically, a two-layer or three-layer structure, for example, a two-layer structure including an acrylic resin layer containing rubber elastic particles / an acrylic resin layer not containing rubber elastic particles, or rubber Examples thereof include a three-layer structure comprising an acrylic resin layer containing elastic particles / an acrylic resin layer not containing rubber elastic particles / an acrylic resin layer containing rubber elastic particles. When laminating a base film having a multilayer structure to a polarizing film to form a polarizing plate, it is preferable to use a layer formed from an acrylic resin containing rubber elastic particles as a bonding surface to the polarizing film. .

  The contents of the rubber elastic particles and the above-described additives in each layer may be different from each other. For example, a configuration in which layers containing no ultraviolet absorber and no infrared absorber are stacked with a layer containing an ultraviolet absorber and / or an infrared absorber interposed therebetween may be employed. In addition, the content of the ultraviolet absorber in the layer made of the acrylic resin containing the rubber elastic particles is larger than the content of the ultraviolet absorber in the layer made of the acrylic resin not containing the rubber elastic particles. In this case, ultraviolet rays can be effectively blocked without deteriorating the color tone of the polarizing plate, and a decrease in the degree of polarization during long-term use can be prevented.

<Formation of base film>
The base film can be formed by any method such as a melt extrusion method or a solvent casting method. When the acrylic resin film described above is used as a protective film for a polyvinyl alcohol polarizing film, the thickness can be arbitrarily selected from the range of usually about 5 to 200 μm. The thickness is preferably 10 μm or more, preferably 150 μm or less, more preferably 100 μm or less.

  When using an acrylic resin, there is a method in which the acrylic resin (including the case where rubber elastic particles and other components are blended) is melt-extruded and formed into a film while being sandwiched between two metal rolls. Preferably employed. In this case, the metal roll is preferably a mirror roll, whereby a base film having excellent surface smoothness can be obtained. When an acrylic resin film is produced with a multilayer structure, a plurality of types of acrylic resins may be co-extruded to form a film.

<Surface treatment that can be arbitrarily added to the base film>
By performing a surface treatment on the base film, it is possible to impart a function that the base film alone did not have. For example, the base film can be subjected to a hard coat treatment from the viewpoint of preventing surface scratches in the assembly process of the liquid crystal module. In addition, functional surface treatment such as antistatic treatment can be performed. In addition, when using this base film as a protective film for a polarizing film and forming a polarizing plate, the antistatic function can be imparted by subjecting the base film to a surface treatment, an adhesive layer, etc. It can also provide to the other part of the polarizing plate in which this base film was incorporated. Other examples of the functional surface treatment for the base film include an antireflection treatment and an antifouling treatment. Furthermore, an antiglare treatment can be performed from the viewpoints of improving visibility, preventing reflection of external light, and reducing moire due to interference between the prism sheet and the color filter. In particular, when such a surface treatment is applied to an acrylic resin film, the value of the shock absorption energy by the Charpy impact test may become extremely smaller than that before the surface treatment. The present invention is applied to a base film having a small energy value. About the form which gives an anti-glare process and makes it an anti-glare film, a term will be explained anew and here, other surface treatment layers are explained in order.

(Hard coat layer)
The hard coat layer has a function of increasing the surface hardness of the base film, and is provided for the purpose of preventing scratches on the surface. The hard coat layer is a pencil hardness test defined in JIS K 5600-5-4: 1999 “General test methods for paints – Part 5: Mechanical properties of coating films – Section 4: Scratch hardness (pencil method)” It is preferable to show a value of 2H or harder in the case where a base film on which a hard coat layer is formed is placed on a glass plate and measured. The material for forming such a hard coat layer is generally cured by heat or light. Examples thereof include organic hard coat materials such as organic silicone, melamine, epoxy, acrylic, and urethane acrylate, and inorganic hard coat materials such as silicon dioxide. Among these, when the substrate film is an acrylic resin film, urethane acrylate-based and polyfunctional acrylate-based hard coat materials are preferable because adhesive strength to the film is good and productivity is excellent.

  The hard coat layer contains various fillers for the purpose of adjusting the refractive index, improving the flexural modulus, stabilizing the volume shrinkage, and improving heat resistance, antistatic properties, antiglare properties, etc., if desired. can do. The hard coat layer can also contain additives such as an antioxidant, an ultraviolet absorber, a light stabilizer, an antistatic agent, a leveling agent, and an antifoaming agent.

(Antistatic layer)
The antistatic layer is provided for the purpose of imparting conductivity to the surface of the base film and suppressing the influence of static electricity. For forming the antistatic layer, for example, a method of applying a resin composition containing a conductive substance (antistatic agent) can be employed. Specifically, an antistatic hard coat layer can be formed by allowing an antistatic agent to coexist in the hard coat material used for forming the hard coat layer described above.

(Antireflection layer)
The antireflection layer is a layer for preventing reflection of external light, and is provided directly on the surface of the base film (a surface exposed to the outside) or via another layer such as a hard coat layer. The base film provided with the antireflection layer preferably has a reflectance of 2% or less at an incident angle of 5 ° with respect to light having a wavelength of 430 to 700 nm, and in particular, is reflected at the same incident angle with respect to light having a wavelength of 550 nm. The rate is preferably 1% or less.

  The thickness of the antireflection layer can be about 0.01 to 1 μm, and more preferably in the range of 0.02 to 0.5 μm. The antireflection layer is formed from a low refractive index layer having a refractive index smaller than the refractive index of the layer (base film, hard coat layer, etc.) on which it is provided, specifically a refractive index of 1.30 to 1.45. Or a plurality of low refractive index layers made of inorganic compounds and high refractive index layers made of inorganic compounds alternately stacked.

  The material for forming the low refractive index layer is not particularly limited as long as it has a low refractive index. Examples thereof include a resin material such as an ultraviolet curable acrylic resin, a hybrid material in which inorganic fine particles such as colloidal silica are dispersed in the resin, and a sol-gel material containing alkoxysilane. Such a low refractive index layer may be formed by applying a polymer that has been polymerized, or may be formed by applying in the state of a monomer or oligomer that becomes a precursor, and then polymerizing and curing. Moreover, it is preferable that each material contains the compound which has a fluorine atom in a molecule | numerator, in order to provide antifouling property.

As the sol-gel material for forming the low refractive index layer, a material having a fluorine atom in the molecule is preferably used. A typical example of a sol-gel material having a fluorine atom in the molecule is polyfluoroalkylalkoxysilane. Polyfluoroalkylalkoxysilanes can be represented, for example, by the formula:
CF ₃ (CF ₂ ) _n CH ₂ CH ₂ Si (OR) ₃
Wherein R represents an alkyl group having 1 to 5 carbon atoms, and n represents an integer of 0 to 12. Especially, the compound whose n in the said formula is 2-6 is preferable.

Specific examples of the polyfluoroalkylalkoxysilane include the following compounds.
3,3,3-trifluoropropyltrimethoxysilane,
3,3,3-trifluoropropyltriethoxysilane,
3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyltrimethoxysilane,
3,3,4,4,5,5,6,6,7,7,8,8,8-tridecafluorooctyltriethoxysilane,
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyltrimethoxysilane,
3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyltriethoxysilane and the like.

  The low refractive index layer may be composed of a cured product of a thermosetting fluorine-containing compound or an active energy ray-curable fluorine-containing compound. The cured product preferably has a dynamic friction coefficient in the range of 0.03 to 0.15, and preferably has a contact angle with water in the range of 90 to 120 °. As the curable fluorine-containing compound, a polyfluoroalkyl group-containing silane compound (for example, the above-mentioned 3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10) , 10-heptadecafluorodecyltriethoxysilane, etc.), and fluorine-containing polymers having a crosslinkable functional group.

  The fluorine-containing polymer having a crosslinkable functional group is obtained by copolymerizing a fluorine-containing monomer and a monomer having a crosslinkable functional group, or by copolymerizing a fluorine-containing monomer and a monomer having a functional group, and then polymer. It can be produced by a method of adding a compound having a crosslinkable functional group to the functional group therein.

  Examples of the fluorine-containing monomer used here include fluoroolefins such as fluoroethylene, vinylidene fluoride, tetrafluoroethylene, hexafluoropropylene, perfluoro-2,2-dimethyl-1,3-dioxole, and others ( Examples thereof include partially or fully fluorinated alkyl ester derivatives of (meth) acrylic acid and completely or partially fluorinated vinyl ethers.

  Monomers having a crosslinkable functional group or compounds having a crosslinkable functional group include monomers having a glycidyl group such as glycidyl acrylate and glycidyl methacrylate; monomers having a carboxyl group such as acrylic acid and methacrylic acid; Examples thereof include monomers having a hydroxyl group such as hydroxyalkyl methacrylate; monomers having an alkenyl group such as allyl acrylate and allyl methacrylate; monomers having an amino group; monomers having a sulfonic acid group.

  The material for forming the low refractive index layer can improve scratch resistance, and therefore includes a sol in which fine particles of inorganic compounds such as silica, alumina, titania, zirconia, and magnesium fluoride are dispersed in an alcohol solvent. It can also consist of things. The inorganic compound fine particles used for this purpose are preferably those having a smaller refractive index from the viewpoint of antireflection properties. Such inorganic compound fine particles may have voids, and silica hollow fine particles are particularly preferable. The average particle size of the hollow fine particles is preferably in the range of 5 to 2,000 nm, more preferably in the range of 20 to 100 nm. The average particle diameter here is a number average particle diameter obtained by observation with a transmission electron microscope.

(Anti-fouling layer)
The antifouling layer is provided for imparting water repellency, oil repellency, sweat resistance, antifouling properties and the like. A suitable material for forming the antifouling layer is a fluorine-containing organic compound. Examples of the fluorine-containing organic compound include fluorocarbon, perfluorosilane, and high molecular compounds thereof. As a method for forming the antifouling layer, a physical vapor deposition method, a chemical vapor deposition method, a wet coating method, or the like typified by vapor deposition or sputtering can be used depending on the material to be formed. The average thickness of the antifouling layer is usually about 1 to 50 nm, preferably 3 to 35 nm.

<Anti-glare film>
The base film can be formed as an antiglare film by forming an antiglare layer on the surface thereof. That is, the antiglare film is composed of a base film and an antiglare layer having a fine surface irregularity formed on the surface thereof. The antiglare layer is a layer having a fine uneven shape on the surface, and is preferably formed from the hard coat material described above.

  The anti-glare layer having a fine irregular shape on the surface is a method of forming a coating film containing organic fine particles or inorganic fine particles on the surface of the base film and providing irregularities based on the fine particles, or contains organic fine particles or inorganic fine particles. After forming a coating film that does or does not contain, it can be formed by a method (also referred to as an embossing method) of transferring the uneven shape by pressing against a roll having an uneven shape on the surface. Such a coating film can be formed by, for example, a method of applying a coating liquid composed of a composition in which organic or inorganic fine particles are blended in a curable transparent resin to the surface of a base film.

(Fine particles)
When blending fine particles to form an antiglare layer, the fine particles should have an average particle size of 0.5 to 5 μm and a refractive index difference of 0.02 to 0.2 from the transparent resin. Is preferred. By using fine particles whose average particle diameter and refractive index difference from the transparent resin are in this range, haze can be effectively expressed. The average particle diameter of the fine particles can be obtained by a dynamic light scattering method or the like. The average particle diameter in this case is a weight average particle diameter.

  As inorganic fine particles for forming the antiglare layer, silica, colloidal silica, alumina, alumina sol, aluminosilicate, alumina-silica composite oxide, kaolin, talc, mica, calcium carbonate, calcium phosphate, and the like can be used. Further, as the organic fine particles, resin particles are generally used. For example, crosslinked polyacrylic acid particles, methyl methacrylate / styrene copolymer resin particles, crosslinked polystyrene particles, crosslinked polymethyl methacrylate particles, silicone resin particles, polyimide particles, etc. Is mentioned.

(Transparent resin used to form the antiglare layer)
The transparent resin for dispersing the inorganic fine particles or the organic fine particles is preferably selected from materials having high hardness (hard coat). As such a transparent resin, a photocurable resin, a thermosetting resin, an electron beam curable resin, and the like can be used. From the viewpoint of productivity and the hardness of the obtained film, a photocurable resin is preferably used. The In general, a polyfunctional acrylate is used as the photocurable resin. For example, di- or tri-acrylate of trimethylolpropane, tri- or tetra-acrylate of pentaerythritol, polyfunctional urethane acrylate which is a reaction product of acrylate having at least one hydroxyl group in the molecule and diisocyanate and so on. These polyfunctional acrylates can be used alone or in combination of two or more as required.

  A mixture of polyfunctional urethane acrylate, polyol (meth) acrylate, and (meth) acrylic polymer having an alkyl group containing two or more hydroxyl groups can also be used as the photocurable resin. The polyfunctional urethane acrylate constituting the photocurable resin is produced using, for example, (meth) acrylic acid and / or (meth) acrylic acid ester, polyol, and diisocyanate. Specifically, by preparing hydroxy (meth) acrylate having at least one hydroxyl group in the molecule from (meth) acrylic acid and / or (meth) acrylic acid ester and polyol, and reacting it with diisocyanate, A polyfunctional urethane acrylate can be produced. The polyfunctional urethane acrylate produced in this way is also the photocurable resin itself listed above. In the production thereof, (meth) acrylic acid and / or (meth) acrylic acid ester may be used singly or in combination of two or more, respectively, and polyol and diisocyanate are similarly used. One type may be used, or two or more types may be used in combination.

  The (meth) acrylic acid ester which is one raw material of the polyfunctional urethane acrylate can be a linear or cyclic alkyl ester of (meth) acrylic acid. Specific examples thereof include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, alkyl (meth) acrylate such as butyl (meth) acrylate, and cyclohexyl (meth). Examples include cycloalkyl (meth) acrylates such as acrylates.

  The polyol that is another raw material of the polyfunctional urethane acrylate is a compound having at least two hydroxyl groups in the molecule. For example, ethylene glycol, propylene glycol, 1,3-propanediol, diethylene glycol, dipropylene glycol, neopentyl glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol, 1,9- Nonanediol, 1,10-decanediol, 2,2,4-trimethyl-1,3-pentanediol, 3-methyl-1,5-pentanediol, neopentyl glycol ester of hydroxypivalic acid, cyclohexanedimethylol, 1 , 4-cyclohexanediol, spiroglycol, tricyclodecane dimethylol, hydrogenated bisphenol A, ethylene oxide-added bisphenol A, propylene oxide-added bisphenol A, trimethylol ethane, trimethylol propylene , Glycerin, 3-methylpentane-1,3,5-triol, pentaerythritol, can be exemplified dipentaerythritol, tripentaerythritol, and the like glucose compound.

  Diisocyanate, which is still another raw material of polyfunctional urethane acrylate, is a compound having two isocyanato groups (—NCO) in the molecule, and various aromatic, aliphatic, or alicyclic diisocyanates can be used. . Specific examples include tetramethylene diisocyanate, hexamethylene diisocyanate, isophorone diisocyanate, 2,4-tolylene diisocyanate, 4,4'-diphenyl diisocyanate, 1,5-naphthalene diisocyanate, 3,3'-dimethyl-4,4 '. -Diphenyl diisocyanate, xylene diisocyanate, trimethylhexamethylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and a nuclear hydrogenated diisocyanate having an aromatic ring among these.

  The polyol (meth) acrylate that constitutes the above-described photocurable resin together with the polyfunctional urethane acrylate is a (meth) acrylate of a compound having at least two hydroxyl groups in the molecule (that is, polyol). Specific examples thereof include pentaerythritol di (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol hexa (meth) acrylate, and 1,6-hexanediol di (meth) acrylate. Etc. These polyol (meth) acrylates may be used alone or in combination. The polyol (meth) acrylate preferably comprises pentaerythritol triacrylate and / or pentaerythritol tetraacrylate.

  In addition to these polyfunctional urethane acrylates and polyol (meth) acrylates, the (meth) acrylic polymer having an alkyl group containing two or more hydroxyl groups constituting the photocurable resin has two hydroxyl groups in one constituent unit. It has an alkyl group as described above. For example, a polymer containing 2,3-dihydroxypropyl (meth) acrylate as a constituent unit, a polymer containing 2-hydroxyethyl (meth) acrylate as a constituent unit together with 2,3-dihydroxypropyl (meth) acrylate, and the like can be mentioned. .

  As described above, by using the acrylic photo-curing resin as exemplified, the adhesion to the base film is improved, the mechanical strength is improved, and the anti-glare property can effectively prevent the surface from being scratched. A film can be obtained.

(Photopolymerization initiator)
Such a photocurable resin is combined with a photopolymerization initiator to form a photocurable resin composition. There are various photopolymerization initiators such as acetophenone, benzophenone, benzoin ether, amine, and phosphine oxide. Examples of compounds classified as acetophenone photopolymerization initiators include 2,2-dimethoxy-2-phenylacetophenone (also known as benzyldimethyl ketal), 2,2-diethoxyacetophenone, 1- (4-isopropylphenyl). 2-hydroxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-2-morpholino-1- (4-methylthiophenyl) propan-1-one, and the like. Examples of compounds classified as benzophenone-based photopolymerization initiators include benzophenone, 4-chlorobenzophenone, and 4,4′-dimethoxybenzophenone. Examples of compounds classified as benzoin ether photopolymerization initiators include benzoin methyl ether and benzoin propyl ether. Examples of compounds classified as amine photopolymerization initiators include N, N, N ′, N′-tetramethyl-4,4′-diaminobenzophenone (also known as Michler's ketone). Examples of the phosphine oxide photopolymerization initiator include 2,4,6-trimethylbenzoyldiphenylphosphine oxide. In addition, xanthone compounds and thioxant compounds are also known as photopolymerization initiators.

  These photopolymerization initiators are commercially available. Examples of typical commercial products are "Irgacure 907" and "Irgacure 184" sold by Swiss Ciba, and "Lucirin TPO" sold by BASF Germany. is there.

(Other components blended in the photocurable resin composition)
A solvent is added to the photocurable resin composition as necessary. In this case, for example, any organic solvent that can dissolve each component constituting the composition, such as ethyl acetate and butyl acetate, can be used. Of course, a mixture of two or more organic solvents can also be used.

  Moreover, the photocurable resin composition may contain a leveling agent, and examples thereof include a fluorine-based or silicone-based leveling agent. Examples of silicone leveling agents include reactive silicone, polydimethylsiloxane, polyether-modified polydimethylsiloxane, and polymethylalkylsiloxane. Among the silicone leveling agents, preferred are reactive silicone and siloxane leveling agents. When a leveling agent made of reactive silicone is used, the surface of the hard coat layer is provided with slipperiness, and excellent scratch resistance can be maintained for a long period of time. Further, if a siloxane leveling agent is used, film formability can be improved.

(Formation of antiglare layer)
When using the photocurable resin as described above for the formation of the antiglare layer, inorganic or organic fine particles are dispersed in each component constituting the photocurable resin composition described above, and then the resin composition is used as a base. A hard coat layer (antiglare layer) in which fine particles are dispersed in a transparent resin can be formed by coating on a material film and irradiating light.

  On the other hand, in the case of forming an antiglare layer having a fine concavo-convex shape by an embossing method, a mold having a fine concavo-convex shape is used, and the shape of the mold is applied to a resin layer formed on a base film. Just transfer it. When forming a fine surface uneven shape by the embossing method, the resin layer to which the uneven shape is transferred may or may not contain inorganic or organic fine particles. An active energy ray-curable resin is suitably used for transferring the uneven shape by the embossing method. Particularly preferably, a UV embossing method using an ultraviolet curable resin is employed.

  In the UV embossing method, an ultraviolet curable resin layer is formed on the surface of a base film and cured while pressing the ultraviolet curable resin layer against the uneven surface of the mold, so that the uneven surface of the mold becomes an ultraviolet curable resin. Transferred to the layer. Specifically, an ultraviolet curable resin is applied onto the base film, and the applied ultraviolet curable resin is brought into close contact with the uneven surface of the mold. The curable resin is cured, and then the shape of the mold is transferred to the ultraviolet curable resin layer by peeling the base film on which the cured ultraviolet curable resin layer is formed from the mold. The kind in particular of ultraviolet curable resin is not restrict | limited, The various thing mentioned above can be used. Further, instead of the ultraviolet curable resin, a visible light curable resin that can be cured with visible light having a wavelength longer than that of ultraviolet light by appropriately selecting a photopolymerization initiator may be used.

  The thickness of the antiglare layer is not particularly limited, but is generally 2 μm or more and 30 μm or less, preferably 3 μm or more, and preferably 20 μm or less. If the antiglare layer is too thin, sufficient hardness cannot be obtained, and the surface tends to be easily scratched. On the other hand, if it is too thick, the film is prone to cracking, or the film is curled due to curing shrinkage of the antiglare layer. Tend to decrease.

  As described above, the antiglare film is provided with haze by the antiglare layer. The haze value is preferably in the range of 5 to 50%. If the haze value is too small, sufficient antiglare performance cannot be obtained, and external light is likely to be reflected on the screen. On the other hand, if the haze value is too large, the reflection of external light can be reduced, but the black display screen is reduced. The haze value is the ratio of the diffuse transmittance to the total light transmittance, and is measured according to JIS K 7136: 2000 “How to determine haze of plastic-transparent material”.

[Shock absorption energy of film]
In the present invention, the surface protection film 14 is bonded to the base film 12 having a shock absorption energy value of less than 50 kJ / m ² by the Charpy impact test, and the value of the shock absorption energy by the Charpy impact test in the bonded state. To be 50 kJ / m ² or more. Here, the Charpy impact test is a technique for measuring the impact absorption energy of plastics as defined in JIS K 7111: 2006 “Plastics-Determination of Charpy impact characteristics-Part 1: Uninstrumented impact test”. is there. In the Charpy impact test, a hammer (pendulum) for punching a test piece punches the test piece in the width direction perpendicular to the length direction. Therefore, the test piece having the long side in the mechanical extrusion direction (MD) of the film gives shock absorption energy in the direction (TD) orthogonal to the MD, and the test piece having the long side of the film TD is Gives shock absorption energy. Thus, the value of the impact absorption energy of MD and TD of a film can be measured by using two types of test pieces whose long side directions are orthogonal within the film. In addition, in this JIS, it is prescribed | regulated about the case where a test piece with a notch is used, and the case where a test piece without a notch is used, but since a film is object here, a test piece without a notch is employ | adopted.

  More specifically, when a Charpy impact test is performed on a test piece whose longitudinal direction is the mechanical flow direction of the film (MD, which is an extrusion direction in the case of an extruded film), the length of the test piece is It is punched with a hammer along a punch line perpendicular to the direction. The punching line at this time is in a direction perpendicular to MD, that is, parallel to TD. Therefore, when this test piece is used, the impact absorption energy of TD of the film can be measured. On the other hand, when a Charpy impact test is performed on a test piece having the TD of the film in the length direction, the test piece is punched with a hammer along a punch line perpendicular to the length direction. The punching line at this time is parallel to the MD. Therefore, when this test piece is used, the impact absorption energy of the MD of the film can be measured.

  In the Charpy impact test, the impact absorption energy of the test piece is measured in accordance with JIS K 7111: 2006. Specifically, for example, a test piece having a width of about 5 to 15 mm and a length of about 70 to 90 mm is punched or cut out from a film having a thickness of 300 μm or less. Next, in order to prevent the specimen from moving due to impact when punched with a hammer, both ends of the specimen in the long side direction are fixed to a support base, and energy required for breaking the specimen with a Charpy impact tester (that is, shock absorption energy) ). It means that a test piece, ie, a film, is hard to break, so that this shock absorption energy is large.

In the present invention, as described above, the base film having a shock absorption energy value of less than 50 kJ / m ² by the Charpy impact test is targeted. The “base film having a shock absorption energy value of less than 50 kJ / m ² by the Charpy impact test” herein refers to a film having a shock absorption energy value of at least one of MD and TD of less than 50 kJ / m ² . Of course, films with impact absorption energy values of less than 50 kJ / m ^{2 for} both MD and TD can also be advantageously targeted. Thus, a film having a shock absorption energy value of less than 50 kJ / m ² by the Charpy impact test is easily broken when it is laminated on another film, and if used as it is, the production efficiency is lowered.

Therefore, a surface protection film is bonded to such a fragile substrate film so that the impact absorption energy value by the Charpy impact test is 50 kJ / m ² or more for both MD and TD. Thereby, there is no possibility of cracking when pasting to another film such as a polarizing film, and a laminated film such as a polarizing plate can be stably produced.

[Surface protect film]
In general, there are two types of surface protective films: a self-adhesive film in which the resin film itself has adhesiveness to other objects, and a film in which an adhesive layer is formed on the surface of a support film. Among these, from the viewpoint of adhesion to the substrate film, as shown in a schematic cross-sectional view in FIG. 1, a surface protective film 14 having a pressure-sensitive adhesive layer 16 formed on the surface of the support film 15 is used. The form which bonds the adhesive layer 16 to the base film 12 is used preferably. Moreover, when using the base film which surface-treated, the self-adhesive surface protection film generally has low adhesiveness to the surface-treated surface and tends to be lifted off. Also from this aspect, it is preferable to use the surface protection film 14 in which the pressure-sensitive adhesive layer 16 is formed on the surface of the support film 15.

  The support film 15 constituting the surface protection film 14 is not particularly limited as long as it is made of a transparent resin. Examples of such transparent resins include acrylic resins typified by polymethyl methacrylate, polyolefin resins typified by polypropylene and polyethylene, polyester resins typified by polybutylene terephthalate and polyethylene terephthalate, and the like. . In particular, it is preferable to use a polyester-based resin as the support film 15 from the viewpoint of easy testability and the value of impact absorption energy by the Charpy impact test.

  The thickness of the base film 12 is not particularly limited, but is preferably in the range of 10 μm to 200 μm from the viewpoint of workability, more preferably in the range of 15 μm to 100 μm, and particularly preferably in the range of 20 μm to 85 μm. When the base film 12 is too thin, the value of impact absorption energy by surface protection and Charpy impact test becomes small. On the other hand, if it is too thick, it tends to be disadvantageous in terms of handling and cost.

  The surface protect film 14 preferably has a haze value of 5% or less, more preferably 3% or less. If the haze of the surface protective film 14 is large, the easy inspection property is impaired, which is not preferable.

  The surface protection film 14 preferably has an adhesion strength to the base film 12 in the range of 0.03 N / 25 mm to 0.2 N / 25 mm, and more preferably 0.03 N / 25 mm to 0.15 N / 25 mm. More preferably, it is in the range of 0.05 N / 25 mm to 0.15 N / 25 mm. If the adhesion to the base film 12 is small, the surface protection film 14 is liable to float (also referred to as tunneling) or peel off, and may be scattered when the base film 12 breaks, possibly contaminating the manufacturing process. is there. On the other hand, when the adhesive force with respect to the base film 12 becomes too large, it is difficult to peel off the surface protection film 14.

  The adhesion force of the surface protection film 14 to the base film 12 can be measured as follows. That is, the surface protection film-attached film 10 in a state where the surface protection film 14 is bonded to the base film 12 has a mechanical flow direction (MD) as a long side, a width of 25 mm or a multiple thereof, and a length of A test piece is prepared by cutting to about 150 mm, and the base film 12 side is bonded to a glass plate using an adhesive and fixed. Next, using a tensile tester, grasp the lengthwise end of the surface protection film 14 (one side having a width of 25 mm or a multiple thereof) and use JIS K 6854-2: 1999 "Adhesive-Peeling adhesive strength. A 180 ° peel test is performed at a gripping movement speed of 300 mm / min according to “Test method-Part 2: 180 degree peeling”. Then, the average peeling force over the peeling length excluding the first 25 mm gripping movement distance from the obtained force-grasping movement distance curve is obtained. This value is the adhesion force to the base film 12 per width of the surface protection film 14 in this test piece. When a test piece having a width of 25 mm is used, this value is directly used as an adhesion force to the base film 12 (unit: N / 25 mm). On the other hand, when a test piece whose width is a multiple of 25 mm is used, the average peel force obtained may be converted per 25 mm width. For example, when a test piece having a width of 100 mm (4 times of 25 mm) is used, the average peel force obtained is multiplied by 1/4 to obtain the adhesion force (N / 25 mm) of the surface protection film 14 to the base film 12. To do.

  The surface protection film 14 only needs to be bonded to at least one surface of the base film 12, and may be bonded to both surfaces of the base film 12. When the surface protection film 14 is bonded to both surfaces of the base film 12, the two surface protection films may be of the same type or different types, but using the same type of surface protection film is advantageous in terms of cost. When the surface protection film is pasted on both surfaces of the base film 12, the surface protection film pasted on the surface to be the pasting surface to the polarizing film may be peeled off immediately before pasting on the polarizing film.

  The width of the surface protection film 14 is preferably the same as the width of the base film 12 or narrower than the width of the base film. From the viewpoint of preventing scattering, it is more preferable that the width of the base film 12 is the same.

[Polarizer]
The film 10 with a surface protection film described above with reference to FIG. 1 is bonded to the polarizing film 22 on the base film 12 side as shown in the schematic cross-sectional view of FIG. 20 can be set. In general, an adhesive is used for the bonding, and the bonding is performed via the adhesive layer 23 in FIG. What is necessary is just to bond both, after apply | coating an adhesive agent to the adhesive surface of either the base film 12 side of the film 10 with a surface protection film, and the polarizing film 22. FIG.

  A transparent resin film 26 that also serves as a protective film can be bonded to the surface of the polarizing film 22 opposite to the surface to which the film 10 with a surface protective film is bonded. The transparent resin film 26 may be made of the same material as the base film 12 or may be made of a different material. Similarly, the transparent resin film 26 can be bonded to the polarizing film 22 using an adhesive, and both are bonded together via the adhesive layer 24 in FIG.

<Polarized film>
The polarizing film 22 constituting the polarizing plate 20 is a step of uniaxially stretching a polyvinyl alcohol resin film according to a known method, a step of adsorbing a dichroic dye by dyeing the polyvinyl alcohol resin film with a dichroic dye. In addition, the polyvinyl alcohol resin film on which the dichroic dye is adsorbed may be manufactured through a step of treating with a boric acid aqueous solution and a step of washing with water after the treatment with the boric acid aqueous solution. The polarizing film thus obtained has an absorption axis in the uniaxially stretched direction.

  As the polyvinyl alcohol resin, a saponified polyvinyl acetate resin can be used. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. 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 degree of saponification of the polyvinyl alcohol resin is usually 85 to 100 mol%, preferably 98 mol% or more. This polyvinyl alcohol-based resin may be modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes can 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.

  What formed such a polyvinyl alcohol-type resin into a film is used as a raw film of a polarizing film. The method for forming the polyvinyl alcohol-based resin into a film is not particularly limited, and a known method is employed. The film thickness of the polyvinyl alcohol-based raw film is not particularly limited, but is, for example, about 10 μm to 150 μm.

  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. Moreover, uniaxial stretching can also be performed in these several steps.

  Uniaxial stretching may be performed by passing between spaced apart rolls having different peripheral speeds, or may be performed by sandwiching with hot rolls. Further, this uniaxial stretching may be dry stretching in which stretching is performed in the air, or wet stretching in which a polyvinyl alcohol-based resin film is stretched using a solvent such as water or an organic solvent. May be. The draw ratio is usually about 3 to 8 times.

  The polyvinyl alcohol resin film can be dyed with the dichroic dye by, for example, a method of immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye. As the dichroic dye, iodine or a dichroic organic dye is used. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to 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. The content of potassium iodide is usually about 0.5 to 20 parts by weight per 100 parts by weight of water. 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 organic 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 organic dye is usually employed. The content of the dichroic organic 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 a method of immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution. The amount of boric acid in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, preferably 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 amount of potassium iodide in the boric acid-containing aqueous solution is usually about 0.1 to 15 parts by weight, preferably 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 150 to 600 seconds, and more preferably 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 is 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. The immersion time is usually about 1 to 120 seconds.

  After washing with water, a drying process is performed to obtain a polarizing film. 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.

  By the drying process, the moisture content of the polarizing film is reduced to a practical level. The water content is usually 5 to 20% by weight, preferably 8 to 15% by weight. When the moisture content is less than 5% by weight, the flexibility of the polarizing film is lost, and the polarizing film may be damaged or broken after drying. On the other hand, when the moisture content exceeds 20% by weight, the thermal stability of the polarizing film tends to be insufficient.

  The thickness of the polarizing film on which the dichroic dye thus obtained is adsorbed and oriented can usually be about 5 to 40 μm.

<Transparent resin film to be bonded to the other side of the polarizing film>
As described above with reference to FIG. 2, the transparent resin film 26 can be bonded to the surface of the polarizing film 22 opposite to the surface to which the base film 12 is bonded. The transparent resin film 22 is not particularly limited as long as it functions as a protective film for a polarizing plate or a retardation film. Can do. Among these, an olefin resin film is preferably used.

(Olefin resin)
The olefin resin is, for example, a resin obtained by polymerizing a chain olefin monomer such as ethylene or propylene, or a cyclic olefin monomer such as norbornene or another cyclopentadiene derivative using a polymerization catalyst.

  Examples of the olefin resin obtained from the chain olefin monomer include polyethylene resins and polypropylene resins. Among these, a polypropylene resin that is a homopolymer of propylene is preferable. Also preferred is a polypropylene copolymer resin in which a comonomer mainly composed of propylene and copolymerizable therewith is usually copolymerized at a ratio of 1 to 20% by weight, preferably 3 to 10% by weight.

  As a comonomer copolymerizable with propylene, ethylene, 1-butene, or 1-hexene is preferable. Among them, ethylene is preferably used because it is relatively excellent in transparency and stretch processability, and a polypropylene copolymer resin obtained by copolymerizing ethylene in a proportion of 1 to 20% by weight, particularly 3 to 10% by weight is preferable. One of things. By making the copolymerization ratio of ethylene 1% by weight or more, an effect of improving transparency and stretch processability appears. On the other hand, when the ratio exceeds 20% by weight, the melting point of the resin is lowered, and the heat resistance required for the protective film or retardation film may be impaired.

  Polypropylene resins can be easily obtained from commercial products. For example, “Prime Polypro” sold by Prime Polymer Co., Ltd. and “Novatech” sold by Nippon Polypro Co., Ltd. ”And“ Wintech ”,“ Sumitomo Noblen ”sold by Sumitomo Chemical Co., Ltd.,“ Sun Aroma ”sold by Sun Aroma Co., Ltd., and the like.

  An olefin resin obtained by polymerizing a cyclic olefin monomer is generally also referred to as a cyclic olefin resin, an alicyclic olefin resin, or a norbornene resin. Here, it is called a cyclic olefin resin.

  Examples of cyclic olefin resins include resins obtained by performing ring-opening metathesis polymerization using cyclopentadiene and olefins by Diels-Alder reaction or a derivative thereof as a monomer, followed by hydrogenation; dicyclopentadiene and A resin obtained by performing ring-opening metathesis polymerization from olefins or (meth) acrylic acid esters by a Diels-Alder reaction or a derivative thereof obtained by Diels-Alder reaction, followed by hydrogenation; norbornene, tetracyclo Resins obtained by conducting ring-opening metathesis copolymerization using dodecene, derivatives thereof, or other cyclic olefin monomers in the same manner and subsequent hydrogenation; norbornene, tetracyclododecene and the like And at least one cyclic olefin selected from derivatives, such as aliphatic or aromatic compound and the addition copolymer are allowed to obtain a resin having a vinyl group.

  Cyclic olefin resins can also be easily obtained on the market. For example, they are produced by TOPAS ADVANCED POLYMERS GmbH in Germany under the trade name and sold by Polyplastics Co., Ltd. in Japan. "TOPAS" (Topas), "Arton" manufactured and sold by JSR Corporation, "ZEONOR" and "ZEONEX" manufactured and sold by Nippon Zeon Corporation, manufactured and sold by Mitsui Chemicals, Inc. “Apel” and so on.

(Olefin resin film)
By forming the chain olefin-based resin or the cyclic olefin-based resin into a film, the transparent resin film 26 bonded to one surface of the polarizing film 22 can be obtained. The method for forming the film is not particularly limited, but the melt extrusion film forming method is preferably employed as in the case of forming the acrylic resin film described above.

  Olefin-based resin films can also be easily obtained on the market. For example, polypropylene resin films are sold under the trade name “FILMAX CPP film”, Sun Tox Co., Ltd. "Santox" sold by Totobo, "Tosero" sold by Tohello, "Toyobo Pyrene Film" sold by Toyobo, and "Trephan" sold by Toray Film Processing Co., Ltd. "Nihon Polyace" sold by Nippon Polyace Co., Ltd. and "Dazai FC" sold by Futamura Chemical Co., Ltd. In the case of cyclic olefin-based resin films, “Zeonor Film” sold by Nippon Zeon Co., Ltd., “Arton Film” sold by JSR Co., Ltd., and the like can be used.

  The transparent resin film 26 can be laminated with an optical functional film on its surface or coated with an optical functional layer. Examples of such an optical functional film and an optical functional layer include an easy adhesion layer, a conductive layer, and a hard coat layer.

(Retardation film)
A retardation film can be obtained by stretching the olefin-based resin film described above and imparting refractive index anisotropy to the film. The stretching method may be appropriately selected depending on the required refractive index anisotropy, and is not particularly limited. For example, longitudinal uniaxial stretching, lateral uniaxial stretching, or longitudinal and transverse sequential biaxial stretching is employed.

Olefin resin has a positive refractive index anisotropy, since most refractive index increases in the stressed direction, the film in which it is uniaxially stretched, the refractive normal n _x> n _y ≒ n _z Gives the rate anisotropy. Here, n _x (in the direction of plane refractive index becomes maximum, the resin having a positive refractive index anisotropy stretching direction) in-plane slow axis direction of the film is the refractive index of, n _y is It is the refractive index in the in-plane fast axis direction of the film (the direction perpendicular to the fast axis in the plane), and _nz is the refractive index in the normal direction of the film. Olefin resin is sequentially biaxially-oriented film provides a refractive index anisotropy of the normal _{n x> n y> n z} .

Moreover, in order to provide a desired refractive index characteristic, a retardation film is manufactured by a method in which a heat-shrinkable film is bonded to a target film and the film is shrunk in place of or along with the stretching process. You can also. This operation is usually performed to obtain a retardation film whose refractive index anisotropy is n _x> n _z> n _y or _{n z> n x ≧ n y} .

  Commercially available retardation films made of olefin resins can also be easily obtained. For example, for retardation films made of cyclic olefin-based resins, “ZEONOR FILM” sold by Nippon Zeon Co., Ltd., “ARTON FILM” sold by JSR Corporation, and Sekisui Chemical Co., Ltd. "Essina retardation film" sold by

[Adhesion of Polarizing Film and Base Film and Adhesion of Polarizing Film and Transparent Resin Film]
As described above, an adhesive is used for bonding the base film 12 and the polarizing film 22 constituting the film 10 with the surface protection film and for bonding the polarizing film 22 and the transparent resin film 26. Prior to the bonding, at least one of the bonding surface to the polarizing film 22 of the base film 12 constituting the film 10 with the surface protection film, the bonding surface to the base film 12 of the polarizing film 22, and the polarizing film 22. At least one of the bonding surface to the transparent resin film 26 and the bonding surface to the polarizing film 22 of the transparent resin film 26 is corona discharge treatment, plasma irradiation treatment, electron beam irradiation treatment, and other surface activation. It is preferable to perform the treatment.

  The adhesive for forming the adhesive layers 23 and 24 shown in FIG. 2 can be arbitrarily selected and used from those that exhibit an adhesive force to the two members. Typically, a water-based adhesive, that is, an active energy ray-curable adhesive containing an adhesive component dissolved in water or an adhesive component dispersed in water, or a component that cures upon irradiation with active energy rays is used. Can be mentioned. From the viewpoint of productivity, an active energy ray-curable adhesive is preferably used.

  First, the water-based adhesive will be described. For example, a composition using a polyvinyl alcohol-based resin or a urethane resin as a main component can be cited as a preferable adhesive.

  When a polyvinyl alcohol-based resin is used as the main component of the water-based adhesive, the polyvinyl alcohol-based resin includes partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, and methylol. It may be a modified polyvinyl alcohol resin such as group-modified polyvinyl alcohol or amino group-modified polyvinyl alcohol. When using a polyvinyl alcohol-based resin as the adhesive component, the adhesive is often prepared as an aqueous solution of a polyvinyl alcohol-based resin. The density | concentration of the polyvinyl alcohol-type resin in adhesive agent aqueous solution is about 1-10 weight part normally with respect to 100 weight part of water, Preferably it is 1-5 weight part.

  In order to improve the adhesiveness, it is preferable to add a curable component such as glyoxal or a water-soluble epoxy resin or a crosslinking agent to the water-based adhesive mainly composed of polyvinyl alcohol-based resin. Examples of water-soluble epoxy resins include polyamide polyamines obtained by reacting a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid and epichlorohydrin. An epoxy resin can be mentioned. Examples of commercially available products of such polyamide polyamine epoxy resins include “Smiles Resin 650” and “Smiles Resin 675” sold by Sumika Chemtex Co., Ltd., and “WS-525” sold by Japan PMC Co., Ltd. And the like can be used preferably. The addition amount of these curable components or crosslinking agents is usually 1 to 100 parts by weight, preferably 1 to 50 parts by weight, with respect to 100 parts by weight of the polyvinyl alcohol resin. If the amount added is small, the effect of improving the adhesiveness is reduced, while if the amount added is large, the adhesive layer tends to be brittle.

  When a urethane resin is used as the main component of the water-based adhesive, a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group can be given as an example of a suitable adhesive composition. The polyester ionomer type urethane resin here is a urethane resin having a polyester skeleton, into which a small amount of ionic component (hydrophilic component) is introduced. Since the ionomer type urethane resin is emulsified directly in water without using an emulsifier to form an emulsion, it is suitable as an aqueous adhesive. The use of polyester ionomer type urethane resin for adhesion between a polarizing film and a protective film is known, for example, from JP-A-2005-70139, JP-A-2005-70140, JP-A-2005-181817, etc. .

  On the other hand, when an activated energy ray-curable adhesive is used, a component that is cured by irradiation of an active energy ray constituting the adhesive (hereinafter sometimes simply referred to as a “curable component”) is an epoxy compound, an oktacene compound, It may be an acrylic compound. When a cationically polymerizable compound such as an epoxy compound or an okitacene compound is used, a cationic polymerization initiator is blended. Further, when a radical polymerizable compound such as an acrylic compound is used, a radical polymerization initiator is blended. Among them, an adhesive having an epoxy compound as one of the curable components is preferable, and an adhesive having an alicyclic epoxy compound in which an epoxy group is directly bonded to a saturated carbocycle as one of the curable components is particularly preferable. It is also effective to use an oxetane compound in combination. Such an active energy ray-curable adhesive in which an epoxy compound is one of the curable components and an oxetane compound is blended as necessary is disclosed in Patent Document 4 (Japanese Patent Laid-Open No. 2004-245925), It is described in Patent Document 5 (Japanese Patent Laid-Open No. 2010-209126).

Epoxy compounds can be easily obtained on the market, for example, "Epicoat" series sold by Japan Epoxy Resin Co., Ltd.
"Epiclon" series sold by DIC Corporation, "Epototo" series sold by Toto Kasei Co., Ltd., "Adeka Resin" series sold by ADEKA Corporation, and Nagase ChemteX Corporation. There are “Denacol” series, “Dow Epoxy” series sold by Dow Chemical Company, and “Tepic” sold by Nissan Chemical Industries, Ltd.

  An alicyclic epoxy compound in which an epoxy group is directly bonded to a saturated carbocyclic ring can also be easily obtained as a commercial product. For example, each product is sold by Daicel Chemical Industries, Ltd. under the trade name. There are "Celoxide" series and "Cyclomer" series, "Syracure" series sold by Dow Chemical.

  Oxetane compounds can also be easily obtained as commercial products. For example, “Aron Oxetane” series sold by Toagosei Co., Ltd. and “ETERNACOLL” sold by Ube Industries, Ltd. "There is a series.

  Cationic polymerization initiators can also be easily obtained as commercial products. For example, “Kayarad” series sold by Nippon Kayaku Co., Ltd. and Union Carbide, Inc. Photo acid generators “CPI” series sold by SyraCure ”series, San Apro Co., Ltd. Photo acid generators“ TAZ ”,“ BBI ”and“ DTS ”sold by Midori Chemical Co., Ltd., from ADEKA Co., Ltd. There are "Adekaoptomer" series sold and "RHODORSIL" series sold by Rhodia.

  The active energy ray-curable adhesive can contain a photosensitizer as necessary. By using a photosensitizer, the reactivity is improved, and the mechanical strength and adhesive strength of the cured product layer can be further improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, anthracene compounds, halogen compounds, and photoreducible dyes.

  Moreover, various additives can be mix | blended with an active energy ray hardening adhesive in the range which does not impair the adhesiveness. Examples of the additive include an ion trap agent, an antioxidant, a chain transfer agent, a tackifier, a thermoplastic resin, a filler, a flow regulator, a plasticizer, and an antifoaming agent. Furthermore, a curable component that cures by a reaction mechanism different from cationic polymerization can be blended within a range that does not impair the adhesion.

  The active energy ray-curable adhesive described above is applied to the bonding surface of the base film 12 or the polarizing film 22 constituting the film 10 with a surface protective film, and after both are bonded via the coating layer, This is cured by irradiating active energy rays to form an adhesive layer 23 that joins the polarizing film 22 and the base film 12. Moreover, after apply | coating to the bonding surface of the polarizing film 22 or the transparent resin film 26 and bonding both through the coating layer, it is hardened by irradiating an active energy ray there, and the polarizing film 22 and a transparent resin film 26 becomes an adhesive layer 24 to which the members 26 are joined. The adhesive for forming the adhesive layer 23 and the adhesive for forming the adhesive layer 24 may have the same composition or different compositions, but the active energy for curing both It is preferable to perform the irradiation of the rays at the same time.

  The active energy ray used for curing the active energy ray-curable adhesive may be, for example, an X-ray having a wavelength of 1 pm to 10 nm, an ultraviolet ray having a wavelength of 10 to 400 nm, a visible ray having a wavelength of 400 to 800 nm, or the like. Among these, ultraviolet rays are preferably used in terms of ease of use, ease of preparation of the active energy ray-curable adhesive, stability, and curing performance. As an ultraviolet light source, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, a metal halide lamp or the like having a light emission distribution at a wavelength of 400 nm or less may be used. it can.

  The thickness of the adhesive layer obtained by using the active energy ray-curable adhesive is usually about 1 to 50 μm, and particularly preferably in the range of 1 to 10 μm.

[Production method of polarizing plate]
A polarizing plate 20 with a surface protection film whose representative example is the configuration shown in FIG. 2 is based on a Charpy impact test in which the surface protection film 14 is bonded to the base film 12 described above and bonded. A film 10 with a surface protection film having a shock absorption energy value of 50 kJ / m ² or more is prepared, and then the base film 12 side of the film 10 with a surface protection film is bonded to the polarizing film 22 described above. It can be manufactured by a method. If necessary, the transparent resin film 26 described above can be bonded to the opposite side of the surface of the polarizing film 22 to which the base film 12 is bonded. The adhesive described above is used for bonding the polarizing film 22 and the base film 12 and for bonding the polarizing film 22 and the transparent resin film 26.

[Use of polarizing plate]
The polarizing plate 20 with a surface protection film whose representative example is the configuration shown in FIG. 2 can be attached to the viewing side of the liquid crystal cell to form a liquid crystal panel used in a liquid crystal display device. Another polarizing plate is bonded to the opposite side of the liquid crystal cell. For bonding to the liquid crystal cell, an adhesive layer can be provided on the outside of the transparent resin film 26, that is, on the side opposite to the bonding surface to the polarizing film 22. This pressure-sensitive adhesive layer is generally formed of an acrylic pressure-sensitive adhesive having an acrylic resin mainly composed of an acrylate ester and an acrylic resin copolymerized with a functional group-containing acrylic monomer. After being bonded to the liquid crystal cell in this way, the surface protective film 14 is peeled off from the polarizing plate 20 with the surface protective film, and a liquid crystal panel in which the base film 12 is disposed on the viewing side is obtained. The liquid crystal cell constituting the liquid crystal panel can be various types used in this field.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to these examples. In the examples, “%” and “part” representing the content or amount used are based on weight unless otherwise specified.

[Control example]
(A) Production of acrylic resin film A copolymer of methyl methacrylate / methyl acrylate having a weight ratio of 96/4 was used as an acrylic resin. The innermost layer is a hard polymer polymerized with methyl methacrylate using a small amount of allyl methacrylate, and the intermediate layer is polymerized with butyl acrylate as the main component, and further using styrene and a small amount of allyl methacrylate. Soft elastic body, the outermost layer is a three-layered elastic particle made of a hard polymer polymerized with methyl methacrylate using a small amount of ethyl acrylate, up to an elastic body that is an intermediate layer Acrylic elastic polymer particles having an average particle size of 240 nm were used.

  The above-mentioned acrylic resin and acrylic elastic polymer particles are blended in a weight ratio of the former / the latter = 70/30, and further, a pellet in which 0.05 part of stearic acid as a lubricant is blended per 100 parts in total. The product was put into a 65 mmφ single screw extruder and extruded from a T-die having a set temperature of 275 ° C. Both sides of the extruded film-like molten resin were sandwiched and cooled by two polishing rolls having mirror surfaces set at 45 ° C., and an acrylic resin film having a thickness of 80 μm was produced in a roll shape.

(A1) Charpy impact test of acrylic resin film A rectangular test piece having a width of 10 mm and a length of 82 mm was cut out from the acrylic resin film obtained above. The test piece is a first test piece in which the mechanical extrusion direction (MD) of the film is the length direction (direction of 82 mm on one side), and the direction perpendicular to MD (TD) is the length direction (the direction of 82 mm on one side). 2) of the second test piece. And both ends of the long side of the test piece are fixed to the support so that the test piece does not move due to impact when punched with a hammer, and the hammer is moved in the longitudinal direction of the blade edge by a Charpy impact tester manufactured by Yasuda Seiki Seisakusyo Co., Ltd. Was struck so as to be parallel to the width direction at the center in the length direction of the test piece, and the energy required for breaking the film (namely, impact absorption energy) was measured. At this time, since the first test piece having the MD of the film in the length direction is broken along the direction orthogonal to the MD, that is, along TD, the impact absorption energy of TD is given, and the TD of the film is taken as the length direction. Since the 2nd test piece to fracture | ruptures along MD, it gives the impact absorption energy of MD. This acrylic resin film had an impact absorption energy of TD obtained from the first test piece of 229 kJ / m ² and an impact absorption energy of MD obtained from the second test piece of 187 kJ / m ^2. It was.

(B) Preparation of coating solution for forming antiglare layer It contains pentaerythritol triacrylate and polyfunctional urethanized acrylate (reaction product of hexamethylene diisocyanate and pentaerythritol triacrylate), and the weight ratio of the former / the latter is 60 / At 40, a photo-curable resin composition was prepared, which was dissolved in ethyl acetate so that the total concentration of both was 60%, and was further blended with a leveling agent. The pentaerythritol triacrylate and polyfunctional urethanized acrylate constituting the photocurable resin composition are collectively referred to as “curable acrylate”. To 100 parts of the curable acrylate of this photocurable resin composition, 5 parts of methyl methacrylate / styrene copolymer resin particles having an average particle size of 2.7 μm are added and dispersed. Further, the curable acrylate and resin particles are dispersed. Diluted with ethyl acetate to a total concentration of 30%. Thereafter, 1 part of “Irgacure 184” (manufactured by Ciba) as a photopolymerization initiator was added to 100 parts of the curable acrylate in the liquid to prepare a coating solution for forming an antiglare layer.

  To the photocurable resin composition used here (in a state where no methyl methacrylate / styrene copolymer resin particles are blended), the above photopolymerization initiator is added to form a film, which is cured by irradiation with ultraviolet rays. The refractive index was 1.53, while the above methyl methacrylate / styrene copolymer resin particles had a refractive index of 1.49. Therefore, the refractive index difference between the two was 0.04.

(C) Production of antiglare film The coating thickness after drying the antiglare layer-forming coating solution prepared in (B) above was 3.4 μm on one side of the acrylic resin film produced in (A) above. The coating film was dried by holding in a dryer set at 60 ° C. for 3 minutes. After drying, light from a high-pressure mercury lamp with an intensity of 20 mW / cm ² is irradiated from the coating side of the film so that the amount of light converted to h-ray is 200 mJ / cm ² to cure the coating layer of the photocurable resin composition. Thus, an antiglare film was produced in which an antiglare layer having irregularities was formed on the surface of the acrylic resin film. The obtained antiglare film was wound around a core having a diameter of 6 inches (about 15 cm). When the haze value of this antiglare film was measured using a haze meter, it was 11.5%. The anti-glare film was subjected to a Charpy impact test using the same method as shown in (A1) above, except that a hammer was applied from the anti-glare layer side, and the impact absorption energy was measured. As a result, the impact absorption energy of TD is 8 kJ / m ^2, the impact absorbing energy of MD was 5 kJ / m ^2.

(E) Production of polarizing plate Fabricated in (C) above with an ultraviolet curable adhesive mainly composed of an epoxy compound on one side of a polarizing film having a thickness of about 30 μm in which iodine is adsorbed and oriented on polyvinyl alcohol. The prepared antiglare film was pasted on the acrylic resin film side, and an attempt was made to produce a polarizing plate. However, the antiglare film was broken during the pasting, and the polarizing plate could not be produced.

[Example 1]
(D) Production of Film with Surface Protect Film A pressure-sensitive adhesive layer was provided on one side of a polyethylene terephthalate film, and a surface protect film having a total thickness of 50 μm was prepared in a roll shape. This surface protection film had a haze of 1.8%. And on the anti-glare layer side of the anti-glare film produced by the same method as in the above-mentioned comparative examples (A) to (C), the pressure-sensitive adhesive surface of this surface protective film is the roll longitudinal direction (MD) of both. Bonding was performed in the same manner to produce a film with a surface protection film. The obtained film with a surface protective film was subjected to a Charpy impact test in the same manner as in the control example (A1) shown above, except that a hammer was applied from the surface protective film side. Energy was measured. As a result, the impact absorption energy of TD was 113 kJ / m ² and the impact absorption energy of MD was 243 kJ / m ² .

(D1) Measurement of adhesion of surface protective film to antiglare film From the film with the surface protective film prepared above, a test piece having a width of 100 mm and a length of 150 mm was cut out with the MD as the length direction, and the antiglare property was obtained. The acrylic resin film surface which comprises a film was bonded to glass using the adhesive. In this state, use a tensile tester to grab the lengthwise end (one side of the width of 100 mm) of the surface protection film (ie, polyethylene terephthalate film + adhesive layer) and use JIS K 6854-2: 1999 “Adhesive— In accordance with “Peeling adhesion strength test method—Part 2: 180 degree peeling”, a 180 degree peeling test was conducted at a gripping moving speed of 300 mm / min. Then, the average peeling force over the peeling length excluding the first 25 mm gripping movement distance is obtained from the obtained force-grasping movement distance curve, and since this value is per 100 mm width, this is converted per 25 mm width, that is, this The value was multiplied by 1/4 to obtain the adhesion of the surface protection film to the base film. This surface protective film exhibited an adhesion of 0.08 N / 25 mm to the antiglare layer surface of the antiglare film.

(E) Production of Polarizing Plate On one side of a polarizing film having a thickness of about 30 μm in which iodine is adsorbed and oriented on polyvinyl alcohol, the film with the surface protective film produced in the above (D) is epoxy-coated on the acrylic resin film side. It is bonded via an ultraviolet curable adhesive containing a compound as a main component, and a retardation film, which is a biaxially stretched product of a cycloolefin resin, is provided on the other surface of the polarizing film. The film was bonded via an ultraviolet curable adhesive, and then the ultraviolet curable adhesive was cured by irradiating with ultraviolet rays to produce an antiglare polarizing plate. At this time, the film with the surface protective film was not broken, and a polarizing plate could be produced.

  In place of the retardation film which is a biaxially stretched product of the cycloolefin resin used here, a triacetyl cellulose film or a polypropylene resin film (each of which a retardation may be imparted) is used in the same manner. A dazzling polarizing plate can be produced.

10: Film with surface protection film,
12 …… Base film,
14 …… Surface protect film,
15 …… Support film,
16 …… Adhesive,
20: Polarizing plate with surface protection film,
22: Polarizing film,
23, 24 ... adhesive layer,
26 …… Transparent resin film.

Claims (6)

A base material having a surface treatment selected from a hard coat treatment, an antistatic treatment, an antireflection treatment, an antifouling treatment and an antiglare treatment on one side having an impact absorption energy value of less than 50 kJ / m ² by a Charpy impact test A surface protection film is bonded to the surface of the film that has been subjected to the surface treatment,
The value of impact absorption energy by the Charpy impact test in the bonded state is 50 kJ / m ² or more,
The surface protection film is a film with a surface protection film having an adhesive force of 0.03 N / 25 mm or more and 0.2 N / 25 mm or less to the base film. The film with a surface protection film according to claim 1, wherein the base film is made of an acrylic resin. The film with a surface protection film according to claim 1 or 2, wherein the surface protection film is a self-adhesive film or a film in which an adhesive layer is formed on the surface of a support film. The surface protection film according to claim 1 or 2, wherein the surface protection film has a pressure-sensitive adhesive layer on one side of a polyester resin film, and is bonded to the base film on the pressure-sensitive adhesive layer side. Film with film. The film with a surface protection film according to any one of claims 1 to 4, wherein the surface protection film has an adhesive force of 0.03 N / 25 mm or more and 0.15 N / 25 mm or less with respect to the base film. A film with a surface protective film according to claim 1, wherein the film with a surface protective film is bonded to a polarizing film on the base film side.

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