JP4233999B2 - Laminated polarizing plate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a laminated polarizing plate and a method for producing the same.

  In a liquid crystal display device, a polarizing plate is generally attached to both surfaces of a liquid crystal cell. However, when the liquid crystal cell with the polarizing plate attached in this way is applied to a viewfinder such as a video camera, a projector, a digital camera, or the like, the following problems occur.

  The viewfinder and the projector take a form in which a light source is irradiated from the back surface of the liquid crystal cell and an illuminated image is enlarged and projected by a magnifying lens system disposed in front of the liquid crystal cell. Therefore, the focal point of the magnifying lens is generally adjusted to the color filter disposed inside the liquid crystal cell. However, since the focal point of the magnifying lens system is close to the liquid crystal cell, as a result It often goes into depth. Then, if foreign matter such as dust adheres to the polarizing plate, even this foreign matter enters within the focal depth of the magnifying lens system, so the outline of this foreign matter is also projected, and the display quality is significantly reduced. It will become. In particular, since the polarizing plate is generally produced by bonding a polarizing film and a transparent protective layer, foreign matter is mixed in the polarizing plate during the production, or when adhering to the liquid crystal cell, There is a possibility that foreign matter may enter the interface between the liquid crystal cell and the polarizing plate.

  In recent years, in order to solve such problems, a method of disposing a polarizing plate with a sufficient distance outside the liquid crystal cell has been newly disclosed (for example, see Patent Document 1). Thus, if the polarizing plate is disposed at a position sufficiently away from the liquid crystal cell, the polarizing plate will not be focused even if the magnification lens system is focused on the liquid crystal cell. For this reason, even when a foreign substance is mixed inside the polarizing plate, the foreign substance does not enter the depth of focus, and the display quality can be prevented from being affected.

JP-A-6-258637

  However, if it is set as the form of the said patent document 1, the following problems will arise. That is, the polarizing plate itself is extremely inferior in rigidity, and it is difficult to arrange the polarizing plate with a sufficient distance from the liquid crystal cell by itself. Therefore, a cover member is further arranged outside the liquid crystal cell substrate, and the polarizing plate is formed thereon. It is essential to stick. For this reason, the manufacturing process becomes complicated, and problems such as an increase in size, an increase in cost, and a reduction in screen size occur.

Therefore, the present invention provides a polarizing plate that can be used in various image display devices without being directly laminated on an image display element such as a liquid crystal cell, and in particular, a method for producing a polarizing plate suitable for use in a viewfinder or a projector. Is an offer.

  The present invention also includes a step of forming a laminate of a polarizing plate and a resin film having a light transmittance of 80% or more and a glass transition temperature of 100 ° C. or more, and a laser is provided on the resin film side of the laminate. Is a method for producing a laminated polarizing plate, comprising the step of cutting the laminate to form a laminated polarizing plate by irradiating the film.

  Thus, if the polarizing plate is laminated with a resin film having a light transmittance of 80% or more and a glass transition temperature of 100 ° C. or more, the strength of the polarizing plate is improved while maintaining transparency. be able to. With such a laminated polarizing plate of the present invention, for example, a sufficient distance is provided between the liquid crystal cell and the polarizing plate without directly attaching to the liquid crystal cell or mounting the transparent cover member as described above. In this state, the laminated polarizing plate can be attached to the image display device alone. Therefore, the laminated polarizing plate of the present invention can be said to be a very useful polarizing plate, for example, for a viewfinder or a projector having the above-described form.

  And the present inventors have found the following further about the manufacturing method of this laminated polarizing plate. That is, the polarizing plate is usually cut to a desired size for use, but since a relatively small polarizing plate is used particularly for viewfinders and projectors, the laser irradiation is exclusively used for the cutting. Was adopted. However, when the polarizing plate is cut with a laser, the polarizing plate is deteriorated due to the heat of the laser, and protrusions such as a scissors are generated on the cut surface, or the cut surface is raised, and further, a cleaning process, etc. However, there is a problem that it is difficult to remove protrusions. In addition, the polarizing plate in which such protrusions are generated has developed into problems such as the protrusions being mixed inside the product when it is attached to a product casing, or a mounting failure due to a bump. Therefore, the present inventors have intensively studied the cutting method for the newly found polarizing plate of a polarizing plate and a resin film, and as a result, even when cutting by laser irradiation, the polarizing plate and the resin film The present inventors have found that the above-described protrusions and protrusions can be prevented only when the laminated body is irradiated with laser on the resin film side. According to this manufacturing method, projections and the like are not generated even by laser irradiation, and therefore problems such as mixing of projections and poor attachment can be prevented when the product is attached to the housing of the product.

  Below, an example of the manufacturing method of this invention is explained in full detail.

  First, the laminated body which laminated | stacked the polarizing plate and the resin film is produced. The polarizing plate is not particularly limited, and a conventionally known polarizing plate as described later can be used.

  The resin film is not particularly limited as long as it has a transmittance of 80% or more and a glass transition temperature of 100 ° C. or higher, but is preferably excellent in transparency, impact resistance, and heat resistance. It can be manufactured using a material to be used. The glass transition temperature can be determined from the peak value of tan δ from the result of viscoelasticity measurement from −30 ° C. to 200 ° C., for example, using a viscoelasticity measuring apparatus ARES manufactured by TA Instruments Japan. .

  The thickness of the resin film is not particularly limited, but is preferably 0.05 mm to 1.5 mm, for example.

  The method for laminating the polarizing plate and the resin film is not particularly limited, and can be performed by a conventionally known method. Moreover, when laminating | stacking with an adhesive agent, the adhesive agent to be used in particular is not restrict | limited, A conventionally well-known thing can be used, The kind can be suitably determined with the material etc. of each said structure.

  Next, the sheet-like laminate is cut by irradiating a laser beam on the resin film side of the laminate produced as described above. Thereby, the laminated polarizing plate of the present invention can be produced. The reason why the above-mentioned protrusions and protrusions can be prevented by such a method is probably that the laser film is not irradiated on the polarizing plate side which is easily affected by heat, but from the resin film side with high heat resistance. This is presumably because the deterioration of the polarizing plate can be suppressed by laser irradiation. In particular, there is a phenomenon that protrusions are likely to occur along the absorption axis direction of the polarizing plate. This is presumed to be because the draw ratio in the absorption axis direction is higher than that in the vertical direction.

  A method for cutting the laminate will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of a method for producing a laminated polarizing plate of the present invention. As shown in FIG. 1, a laser beam is irradiated from the resin film 11 side, that is, in the direction of arrow 10 in the figure, to a laminate in which a polarizing plate 13 and a resin film 11 are laminated via an adhesive layer 12. do it.

Examples of the laser include a CO ₂ laser, a YAG laser, and a UV laser, and among these, a CO ₂ laser is preferable because it is highly applicable in the thickness range and does not cause cracking or notch. In the laser irradiation, the output and the speed are not limited, and the laser irradiation may be performed by a single irradiation or a plurality of irradiations. The output of the laser irradiation is, for example, 10 W to 800 W, preferably 100 W to 350 W when cutting with one irradiation, and preferably 50 W to 200 W when cutting with two irradiations.

  The shape of the laminated polarizing plate cut out from the laminate is not particularly limited, but is generally quadrangular, and it may be cut out in the absorption axis direction and the vertical axis direction (polarization axis and perpendicular direction) in the polarizing plate in the laminate. . Specifically, at least 300 laminated polarizing plates (for viewfinder) having a product size of 10 mm × 11 mm can be obtained from a sheet-like laminate of 360 mm × 280 mm, for example.

  In addition, if the laminate is bonded onto a surface protective sheet via an adhesive and laser irradiation is performed, finally, a plurality of cut laminated polarizing plates are deposited on one surface protective sheet. Sheets can be provided. In such a form, a plurality of laminated polarizing plates can be carried and stored with a single sheet, which is useful in the distribution process.

  Thus, the following method is mentioned as a method of sticking a plurality of laminated polarizing plates on one sheet. First, after sticking the laminate to the surface protective sheet via an adhesive, only either the absorption axis or the vertical axis of the polarizing plate in the laminate, that is, either the horizontal direction or the vertical direction. Then, cutting is performed by laser irradiation from the resin film side. And after peeling off the said surface protection sheet, a new surface protection sheet is again laminated | stacked on the said laminated body via an adhesive, and the laser irradiation is performed to the other axial direction which is not cut | disconnected next. As a result, the laminate is in a state where both the absorption axis and the vertical axis are cut, but the newly re-applied surface protection sheet is cut because only one axial direction is cut. The laminated polarizing plate is stuck on the surface protective sheet without being separated. In addition, a surface protection sheet may be affixed on any one surface of the said laminated body, and may be affixed on both surfaces.

  FIG. 2 shows a plan view of an example in which a plurality of the laminated polarizing plates of the present invention are arranged on the surface protective sheet as described above. As shown in the figure, on the surface protection sheet 22, laminated polarizing plates 21 cut out in the polarization axis direction and the absorption axis direction are arranged at equal intervals. The arrow B in the figure indicates the absorption axis direction of the polarizing plate, the arrow A indicates the axial direction (vertical axis direction) perpendicular to the absorption axis in the plane, and both are orthogonal.

  The laminated polarizing plate of the present invention is preferably subjected to a cleaning treatment before use, for example, when the surface or the cut surface is contaminated by a gas generated during laser irradiation. The cleaning method is not particularly limited, and for example, it may be wiped off with a dust-resistant cloth for removing gas contamination impregnated with a solvent such as alcohol. Alternatively, any one of the surface protective sheets may be peeled off and replaced after washing, and the opposite surface may be peeled off and washed again, and then pasted again.

In the case of the form shown in FIG. 2, the pitch between the stacked polarizing plates is not particularly limited, but for example, it is preferable to increase the pitch along the absorption axis direction. This is because the cut surface (b in FIG. 2) in the absorption axis direction B can be easily cleaned. That is, the absorption axis direction B of the polarizing plate corresponds to the stretching direction of the polarizer (polarizing film), and is generally a direction weak against heat as compared with the vertical axis direction. For this reason, a protrusion may generate | occur | produce in the cut surface b of a laminated polarizing plate. Therefore, if the pitch along the absorption axis direction is increased in this way, the cleaning solvent can easily flow between the pitches, and the cleaning process can be performed efficiently. The pitch interval in the absorption axis direction (arrow A) of the polarizing plate is preferably 0.3 mm or more and 3 mm or less, for example.

  Next, in the production method of the present invention, a conventionally known polarizing plate can be used, and in general, a polarizing plate (polarizing film) having a transparent protective layer disposed on one side or both sides thereof can be mentioned. The polarizer is not particularly limited, and a conventionally known polarizing film can be used. Specifically, for example, a film prepared by adsorbing a dichroic substance such as iodine or a dichroic dye to various films by using a conventionally known method, crosslinking, stretching, and drying are used. it can. Among these, a film that transmits linearly polarized light when natural light is incident is preferable, and a film that is excellent in light transmittance and degree of polarization is preferable. Examples of the various films for adsorbing the dichroic substance include hydrophilic polymer films such as PVA films, partially formalized PVA films, ethylene / vinyl acetate copolymer partially saponified films, and cellulose films. In addition to these, polyene oriented films such as PVA dehydrated products and polyvinyl chloride dehydrochlorinated products can also be used. Among these, PVA film is preferable. Moreover, although the thickness of the said polarizing film is the range of 5-80 micrometers normally, it is not limited to this.

  The transparent protective layer is not particularly limited, and a conventionally known transparent film can be used. For example, a layer having excellent transparency, mechanical strength, thermal stability, moisture barrier property, isotropy, and the like is preferable. Specific examples of the material for such a transparent protective layer include polyester polymers such as polyethylene terephthalate and polyethylene naphthalate, cellulose polymers such as diacetyl cellulose and triacetyl cellulose, acrylic polymers of polymethyl (meth) acrylate, polystyrene and the like. Examples thereof include styrene polymers such as acrylonitrile / styrene copolymer (AS resin), polycarbonate polymers, and the like. In addition, polyethylene, polypropylene, polyolefin having a cyclo or norbornene structure, polyolefin polymer such as ethylene / propylene copolymer, vinyl chloride polymer, nylon or aromatic polyamide polymer, imide polymer, sulfone polymer, polyether sulfone Polymers, polyether ether ketone polymers, vinylidene chloride polymers, vinyl alcohol polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers, blends of the above-mentioned various polymers, and the like. Of these, cellulosic polymers are preferred. Although the thickness of a transparent protective film does not have limitation in particular, Generally it is 500 micrometers or less, 1-300 micrometers is preferable, More preferably, it is 5-200 micrometers.

  Adhesion between the polarizer and the transparent protective layer is not particularly limited, and for example, an isocyanate adhesive, a polyvinyl alcohol adhesive, a gelatin adhesive, a vinyl latex, an aqueous proester, or the like can be used.

  The surface of the polarizing plate can be subjected to various treatments such as hard coat treatment, antireflection treatment, anti-sticking treatment, diffusion treatment, antiglare treatment, antiglare treatment with antireflection, antistatic treatment, and antifouling treatment. May be applied.

  The hard coat treatment is performed for the purpose of preventing scratches on the surface of the polarizing plate, for example, by a method of forming a cured film having excellent hardness and slip properties on the surface of the film by using an ultraviolet curable resin such as acrylic or silicone. be able to. The antireflection treatment is performed for the purpose of preventing reflection of external light on the surface of the optical film, and can be performed by forming a conventionally known antireflection film (physical optical thin film, coating thin film) or the like.

  The anti-glare treatment is intended to prevent the external light from being reflected on the surface of the optical film and preventing the visibility of the light transmitted through the polarizing plate from being impaired. For example, a fine concavo-convex structure may be imparted to the film surface by thinning the film by a sandblasting method, an embossing method, or the like, or by a film forming method in which transparent fine particles are blended in a film forming material. The fine particles to be included in the formation of the fine surface irregularities have an average particle size of, for example, 0.5 to 50 μm, and are organic such as silica, alumina, titania, zirconia, tin oxide, indium oxide, cadmium oxide, and antimony oxide. Transparent fine particles composed of a system material can be used. When forming a fine surface relief structure, the amount of fine particles used is generally about 2 to 50 parts by weight, preferably 5 to 25 parts by weight, per 100 parts by weight of the resin. The anti-glare layer may also serve as a diffusion layer (such as a visual enlargement function) for diffusing the light transmitted through the polarizing plate to enlarge vision.

  The lamination method of the polarizer and the transparent protective layer is not particularly limited, and can be performed by a conventionally known method, for example, an isocyanate adhesive, a polyvinyl alcohol adhesive, a gelatin adhesive, a vinyl latex adhesive. Agents, water-based polyesters, etc. can be used. These types can be appropriately determined depending on the material of the polarizer and the transparent protective layer.

  Next, as the resin film that can be used in the production method of the present invention, those having excellent transparency, impact resistance, and heat resistance as described above are preferable, for example, epoxy resins, polyester resins, methacrylic resins, Polycarbonate (PC) resin, polyethylene naphthalate (PEN) resin, polyethylene terephthalate (PET) resin, triacetyl cellulose (TAC), polynorbornene resin (for example, trade name Arton resin; manufactured by JSR) , Polyimide resins, polyetherimide resins, polyamide resins, polysulfone resins, polyphenylene sulfide resins, polyethersulfone resins, and the like. Among these, epoxy resins are preferred. One kind of these may be used, or two or more kinds may be used in combination.

  The epoxy resin preferably has an epoxy equivalent of 100 to 1000 and a softening point of 120 ° C. or less from the viewpoint of physical properties such as flexibility and strength of the obtained resin sheet. Furthermore, from obtaining an epoxy resin-containing liquid that is excellent in coating properties and developability into a sheet, etc., for example, use a two-component mixed type that shows a liquid state at a temperature below the coating temperature, particularly at room temperature. Is preferred.

  Examples of the epoxy resin include bisphenol A type, bisphenol F type, bisphenol S type, bisphenol type obtained by adding water thereto; novolak type such as phenol novolak type and cresol novolak type; triglycidyl isocyanurate type and hydantoin type Nitrogen-containing ring type; alicyclic type; aliphatic type; aromatic type such as naphthalene type; low water absorption type such as glycidyl ether type and biphenyl type; dicyclo type, ester type, ether ester type, and modifications thereof Examples include molds. Among these, bisphenol A type epoxy resin, alicyclic epoxy resin, and triglycidyl isocyanurate type are preferable, and alicyclic epoxy resin is particularly preferable from the viewpoint of discoloration prevention. One kind of these may be used, or two or more kinds may be used in combination.

  Moreover, since the said epoxy resin is excellent in optical isotropy, it is preferable that a phase difference is 5 nm or less, Most preferably, it is 1 nm.

  In addition, epoxy resins, curing agents, curing accelerators, and conventionally used anti-aging agents, modifiers, surfactants, dyes, pigments, anti-discoloring agents, UV absorbers, etc. You may mix | blend well-known various additives suitably. As a compounding example, it is used by blending and curing an acid anhydride curing agent and a phosphorus curing catalyst in an epoxy resin such as a bisphenol A type epoxy resin, an alicyclic epoxy resin, or a triglycidyl isocyanurate type. Can do.

  The said hardening | curing agent is not restrict | limited in particular, According to the epoxy resin kind to be used, it can determine suitably. Specific examples include organic acid compounds such as tetrahydrophthalic acid, methyltetrahydrophthalic acid, hexahydrophthalic acid and methylhexahydrophthalic acid; ethylenediamine, propylenediamine, diethylenetriamine, triethylenetetramine and their amine adducts, metaphenylene Amine compounds such as diamine, diaminodiphenylmethane and diaminodiphenylsulfone; Amide compounds such as dicyandiamide and polyamide; Hydrazide compounds such as dihydragit; Methylimidazole, 2-ethyl-4-methylimidazole, Ethylimidazole, Isopropylimidazole 2,4-dimethylimidazole, phenylimidazole, undecylimidazole, heptadecylimidazole and 2-phenyl-4-methylimidazole Imidazole compounds such as methyl; methyl imidazoline, 2-ethyl-4-methyl imidazoline, ethyl imidazoline, isopropyl imidazoline, 2,4-dimethyl imidazoline, phenyl imidazoline, undecyl imidazoline, heptadecyl imidazoline and 2-phenyl-4 -Imidazoline compounds such as methyl imidazoline; phenol compounds; urea compounds; polysulfide compounds; acid anhydride compounds. These may be used alone or in combination of two or more. Among them, it is preferable to use acid anhydride compounds because they are excellent in preventing discoloration.

  Examples of the acid anhydride compounds include phthalic anhydride, maleic anhydride, trimellitic anhydride, pyromellitic anhydride, nadic anhydride, glutaric anhydride, tetrahydrophthalic anhydride, methyltetrahydrophthalic anhydride. , Hexahydrophthalic acid anhydride, methyl hexahydrophthalic acid anhydride, methyl nadic acid anhydride, dodecenyl succinic acid anhydride, dichlorosuccinic acid anhydride, benzophenone tetracarboxylic acid anhydride, chlorendic acid anhydride, trihydroxyethyl And isocyanurate anhydride. Among these, colorless to light yellow and those having a molecular weight of about 140 to about 200 are preferable. Specific examples include trihydroxyethyl isocyanurate-modified phthalic anhydride, tetrahydrophthalic anhydride, hexahydrophthalic anhydride. And methylhexahydrophthalic anhydride.

  The blending ratio of the epoxy resin and the curing agent is, for example, when an acid anhydride curing agent is used as the curing agent, the acid anhydride equivalent is 0.5 to 1 with respect to 1 equivalent of the epoxy group of the epoxy resin. It is preferable to mix | blend so that it may become 5 equivalent, More preferably, it is 0.7-1.2 equivalent. If it is such a range, the more excellent hue and moisture resistance will be shown after hardening. In addition, also when using another hardening | curing agent individually or in combination of 2 or more types, the compounding ratio is based on the said equivalent ratio.

  Examples of the curing accelerator include tertiary amines, imidazoles, quaternary ammonium salts, organometallic salts, phosphorus compounds, urea compounds, and the like, among these, particularly tertiary amines. In addition, imidazoles and phosphorus compounds are preferable. One kind of these may be used, or two or more kinds may be used in combination.

  It is preferable that the compounding quantity of the said hardening accelerator is 0.05-7.0 weight part with respect to 100 weight part of epoxy resins, More preferably, it is 0.2-4.0 weight part. If it is such a range, sufficient hardening promotion effect can be acquired and discoloration can fully be prevented.

  The anti-aging agent is not particularly limited, and conventionally known materials can be used, and examples thereof include phenol compounds, amine compounds, organic sulfur compounds, phosphine compounds, and the like.

  The modifying agent is not particularly limited, and conventionally known ones can be used, and examples thereof include glycols, silicones and alcohols.

  A surfactant may be further added to the epoxy resin. By adding the surfactant, the surface of the sheet can be made smoother when the epoxy resin sheet is formed while being in contact with air by the casting method. Examples of the surfactant include silicones, acrylics, and fluorines, and silicones are particularly preferable.

  The method for producing the resin film is not particularly limited, and can be produced by a conventionally known method. Examples thereof include a casting method, a casting method, an injection method, an extrusion method, and a roll coating method.

  Further, for example, a gas barrier layer, a hard coat layer, or the like may be formed on the resin film. The material for forming these layers, the forming method and the thickness thereof are not particularly limited. As an example of the forming material, polyvinyl alcohol or a partially saponified product thereof is preferable as the gas barrier layer, and a thermosetting or radiation curable (for example, UV, EB, etc.) three-dimensional cross-linking acrylic type is used as the hard coat layer. Epoxy resins are preferred.

  The adhesive that can be used in the present invention is not particularly limited, and examples thereof include acrylic, vinyl alcohol, silicone, polyester, polyurethane, polyether, and other polymer adhesives, rubber adhesives, and the like. It is done. Further, an adhesive composed of a water-soluble crosslinking agent of vinyl alcohol polymers such as glutaraldehyde, melamine and oxalic acid can be used. For example, the adhesive is hardly peeled off due to the influence of humidity and heat, and is excellent in light transmittance and polarization degree. Among these, acrylic adhesives are most preferably used from the viewpoint of transparency and durability. The adhesive is not limited to the type, for example, a thermal crosslinking type, a light (ultraviolet ray, electron beam) crosslinking type, or the like.

  The acrylic adhesive may be composed mainly of an acrylic polymer having transparency and the dynamic storage elastic modulus, and optionally added with an additive, and may be combined with an inorganic filler or the like. What you did is fine. The acrylic polymer is mainly composed of (meth) acrylic acid alkyl ester, and has an OH group, a COOH group, an amino group, an amide group, in order to increase the adhesion with the protective film of the polarizing plate through the undercoat layer. It is obtained by adding a modifying monomer that can be copolymerized with the main component having a polar group such as a sulfonic acid group and a phosphoric acid group, and polymerizing these by a conventional method. For the purpose of adjustment, a crosslinking treatment is appropriately performed as necessary.

  As the (meth) acrylic acid alkyl ester, a linear or branched (meth) acrylic acid alkyl ester having an alkyl group having, for example, 1 to 18, preferably 4 to 12 carbon atoms is used. Specific examples include butyl (meth) acrylate, isobutyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, isooctyl (meth) acrylate, (meth), isononyl acrylate, Examples include allyl (meth) acrylate, lauryl (meth) acrylate, stearyl (meth) acrylate, and the like. These may be used alone or in combination of two or more. This monoethylenically unsaturated monomer copolymerizable with this (meth) acrylic acid alkyl ester is used in combination with a monomer having the following polar group in order to improve adhesion to the polarizing plate through the undercoat layer. May be.

  Examples of the monomer having a polar group include carboxyl group-containing monomers such as acrylic acid, methacrylic acid, carboxyethyl acrylate, carboxypentyl acrylate, itaconic acid, maleic acid, fumaric acid, and crotonic acid; maleic anhydride, anhydrous Acid anhydride monomers such as itaconic acid; styrene sulfonic acid, allyl sulfonic acid, 2- (meth) acrylamide-2-methylpropane sulfonic acid, (meth) acrylamide propane sulfonic acid, sulfopropyl (meth) acrylate, (meth) acryloyl Sulfonic acid group-containing monomers such as oxynaphthalene sulfonic acid; Phosphoric acid group-containing monomers such as 2-hydroxyethylacryloyl phosphate; (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N-butyl (meth) acrylic (N-substituted) amide monomers such as amide, N-methylol (meth) acrylamide, N-methylolpropane (meth) acrylamide; aminoethyl (meth) acrylate, N, N-dimethylaminoethyl (meth) acrylate, (Meth) acrylic acid alkylaminoalkyl monomers such as (meth) acrylic acid t-butylaminoethyl; (meth) acrylic acid alkoxyalkyl monomers such as (meth) acrylic acid methoxyethyl and (meth) acrylic acid ethoxyethyl; Succinimide monomers such as N- (meth) acryloyloxymethylene succinimide, N- (meth) acryloyl-6-oxyhexamethylene succinimide, N- (meth) acryloyl-8-oxyoctamethylene succinimide; vinyl acetate, vinyl propionate, -Vinylpyrrolidone, methylvinylpyrrolidone, vinylpyridine, vinylpiperidone, vinylpyrimidine, vinylpiperazine, vinylpyrazine, vinylpyrrole, vinylimidazole, vinyloxazole, vinylmorpholine, N-vinylcarboxylic amides, styrene, α-methylstyrene, N -Vinyl monomers such as vinyl caprolactam; Cyanoacrylate monomers such as acrylonitrile and methacrylonitrile; Epoxy group-containing acrylic monomers such as glycidyl (meth) acrylate; Polyethylene glycol (meth) acrylate, Polypropylene (meth) acrylate Glycol acrylic ester monomers such as glycol, methoxyethylene glycol (meth) acrylate, and methoxypolypropylene glycol (meth) acrylate ; (Meth) acrylic acid tetrahydrofurfuryl, fluorine (meth) acrylate, silicone (meth) acrylate, acrylic ester monomers such as 2-methoxyethyl acrylate.

  When the (meth) acrylic acid alkyl ester and the monoethylenically unsaturated monomer are copolymerized, the blending ratio of the main component (meth) acrylic acid alkyl ester is, for example, 60 to 95% by weight, preferably The blending ratio of the monoethylenically unsaturated monomer may be appropriately set so as to be 100% by weight with the (meth) acrylic acid alkyl ester, for example, 40 to 5%. % By weight, preferably 20 to 5% by weight. By using in such a range, the crack prevention adhesive which is excellent in adhesiveness with a polarizing plate through an undercoat layer, and has a favorable impact force relaxation characteristic can be obtained.

  The acrylic polymer can be adjusted using a conventionally known method. For example, a mixture of the main component and two or more monomers corresponding to the polar group-containing monomer can be adjusted by a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, a suspension polymerization method, or the like. In this case, a polymerization initiator may be used as necessary, and examples thereof include a thermal polymerization initiator and a photopolymerization initiator.

  Examples of the thermal polymerization initiator include benzoyl peroxide, t-butyl perbenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, di-n-propyl peroxydicarbonate, di (2-ethoxyethyl) peroxide. Organic peroxides such as oxydicarbonate, t-butylperoxyneodecanoate, t-butylperoxybivalate, (3,5,5-trimethylhexanoyl) peroxide, dipropionyl peroxide, diacetyl peroxide; 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane 1-carbonitrile), 2,2′-azobis (2, 4-dimethylvaleronitrile), 2,2′-azobis (2,4-dimethyl-4-methoxyvaleronitrile) Dimethyl 2,2′-azobis (2-methylpropionate), 4,4′-azobis (4-cyanovaleric acid), 2,2′-azobis (2-hydroxymethylpropionitrile), 2,2 And azo compounds such as' -azobis [2- (2-imidazolin-2-yl) propane].

  Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone, α-hydroxy-α, α′-dimethylacetophenone, methoxyacetophenone, and 2,2-dimethoxy. Acetophenone compounds such as 2-phenylacetophenone, 2,2-diethoxyacetophenone, 1-hydroxycyclohexyl phenyl ketone, 2-methyl-1- [4- (methylthio) -phenyl] -2-morpholinopropane-1; benzoin Benzoin ether compounds such as ethyl ether, benzoin isopropyl ether and anisoin methyl ether; α-ketol compounds such as 2-methyl-2-hydroxypropiophenone; ketal compounds such as benzyldimethyl ketal; 2-naphthalenesulfonyl Black Aromatic sulfonyl chloride compounds such as 1; phenone-1,1-propanedione-2- (ο-ethoxycarbonyl) oxime and other photoactive oxime compounds; benzophenone, benzoylbenzoic acid, 3,3′-dimethyl And benzophenone compounds such as -4-methoxybenzophenone.

  The usage-amount of these polymerization initiators can be suitably determined according to the kind within the range of 0.005-5 weight part per 100 weight part of monomers, for example. When using the said photoinitiator, it is preferable that it is 0.005-1 weight part, for example, 0.05-0.5 weight part especially. Within such a range, the reactivity between the monomer and the photopolymerization initiator is excellent, the adhesiveness between the adhesive layer and the polarizing plate or the resin film is excellent, and the hue is also excellent. When using a thermal polymerization initiator, for the same reason as described above, for example, 0.01 to 5 parts by weight, particularly 0.05 to 3 parts by weight is preferable.

  In performing the polymerization reaction, a polyfunctional (meth) acrylate having two or more (meth) acryloyl groups in the molecule as a cross-linking agent (internal crosslinking agent) is added together with the polymerization initiator as necessary. The shear strength may be increased by increasing the cohesive force of the impact force relaxation member. Examples of such polyfunctional (meth) acrylates include hexanediol di (meth) acrylate, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) acrylate, neopentyl glycol di (meth) ) Acrylate, pentaerythritol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, epoxy acrylate, polyester acrylate, urethane acrylate and the like.

  The amount of the polyfunctional (meth) acrylate used is, for example, 0.01 to 10 parts by weight, preferably 0.05 to 5 parts by weight per 100 parts by weight of the monomer. On the other hand, in the case of a trifunctional or higher polyfunctional, it is preferable that the number is small. By setting it as such a range, the outstanding crosslinking degree is shown after photopolymerization, and it is excellent in the adhesiveness of an adhesive bond layer, a polarizing plate, or a resin film.

  The polymerization reaction can be performed by, for example, a photopolymerization method such as ultraviolet rays or a thermal polymerization method, depending on the type of the polymerization initiator. From the viewpoint of processability to the pressure-sensitive adhesive sheet and physical properties of the adhesive, the photopolymerization method is particularly preferable. The photopolymerization method is preferably performed, for example, in an oxygen-free atmosphere substituted with an inert gas such as nitrogen gas, or in a state where it is shielded from air by coating with an ultraviolet transmissive film.

In the photopolymerization method, ultraviolet rays are electromagnetic radiation having a wavelength range of about 180 to 460 nm, but may be electromagnetic radiation having a longer wavelength or shorter wavelength. As the ultraviolet ray source, for example, an irradiation device such as a mercury arc, a carbon arc, a low-pressure mercury lamp, a medium / high-pressure mercury lamp, a metal halide lamp, a chemical lamp or a black light lamp can be used. The intensity of the ultraviolet light can be appropriately set by adjusting the distance to the irradiated object or the voltage. In consideration of irradiation time (productivity), it is usually desirable to use an integrated light amount of 0.5 to ¹⁰ J / cm ² . Furthermore, when the thickness of the crack preventing adhesive is 0.2 mm or more, the adhesive may swell due to its polymerization heat, and the swell of the adhesive can be suppressed by cooling during photopolymerization.

  If necessary, the adhesive may further contain one or more plasticizers having good transparency. The blending amount is, for example, 5 to 300 parts by weight, preferably 10 to 200 parts by weight, per 100 parts by weight of the monomer (or polymer thereof).

  Examples of such plasticizers include dimethyl phthalate, diethyl phthalate, dibutyl phthalate, diheptyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate, diisodecyl phthalate, dibutylbenzyl phthalate, and dioctyl phthalate. Phthalic acid compounds such as butylphthalylbutyl glycolate, diisobutyl adipate, diisononyl adipate, diisodecyl adipate, dibutoxyethyl adipate, dibutyl sebacate, di-2-ethylhexyl sebacate, etc. Sebacic acid compounds such as triethylene phosphate, triphenyl phosphate, tricresyl phosphate, trixylenyl phosphate, cresylphenyl phosphate, and other fatty acid compounds such as dioctyl sebacate and methylacetylricinolate , Epoxy compounds such as diisodecyl-4,5-epoxytetrahydrophthalate, trimellitic compounds such as tributyl trimellitic acid, tri-2-ethylhexyl trimellitic acid, tri-n-octyl trimellitic acid, triisodecyl trimellitic acid Other examples include butyl oleate, chlorinated paraffin, polypropylene glycol, polytetramethylene glycol, or polyoxyalkylene glycols such as polybutene and polyisobutylene.

  Furthermore, for the adhesive, as long as the transparency is not impaired, for example, a pigment having absorption characteristics of near infrared (800-1100 nm) or neon light (570-590 nm), a dye such as a dye, a tackifier, Appropriate additives such as antioxidants, antioxidants, ultraviolet absorbers, silane coupling agents, natural products, synthetic resins, acrylic oligomers, glass fibers, and glass beads may be blended. Moreover, it is good also as an adhesive agent which contains microparticles | fine-particles and shows light diffusibility.

  In the production method of the present invention, the surface protection sheet is preferably a sheet containing a resin having excellent mechanical strength and excellent heat resistance, such as a polyester polymer such as polyethylene terephthalate and polyethylene naphthalate, diacetyl cellulose, triacetyl cellulose, and the like. Cellulose polymers, acrylic polymers of polymethyl (meth) acrylate, styrene polymers such as polystyrene and acrylonitrile / strain copolymer (AS resin), and polycarbonate polymers. Polyethylene / polypropylene, polyolefins having a cyclo or norbornene structure. Polyolefin polymers such as ethylene and propylene copolymers, vinyl chloride polymers, nylon and aromatic polyamide polymers, imide polymers, sulfone polymers, polyether sulfone polymers, polyether ether ketone polymers, vinylidene chloride polymers, Examples thereof include vinyl alcohol polymers, vinyl butyral polymers, arylate polymers, polyoxymethylene polymers, epoxy polymers, and blends of the aforementioned polymers. Of these, polyesters such as polyethylene terephthalate and polyethylene naphthalate are preferred.

  Next, an example in which the laminated polarizing plate of the present invention is used in, for example, a liquid crystal display device will be described.

  The liquid crystal display device of the present invention is a liquid crystal display device including a liquid crystal cell and a polarizing plate, wherein the polarizing plate is the laminated polarizing plate of the present invention, and the laminated polarizing plate is separated from the liquid crystal cell. It is preferable to arrange in a state. Moreover, it is preferable that a space is formed between the laminated polarizing plate and the liquid crystal cell.

  An example of the liquid crystal display device of the present invention is shown in the sectional view of FIG. As shown, the liquid crystal cell 31 and the laminated polarizing plate 32 of the present invention are included, and the liquid crystal cell 31 and the polarizing plate 32 are separated from each other, and the polarizing plate 32 includes a polarizing plate 303 and a resin. Film 302. An arrow 300 in the figure indicates the eyepiece direction.

  The type of the liquid crystal cell forming the liquid crystal display device can be arbitrarily selected. For example, it is represented by an active matrix driving type represented by a thin film transistor type, a twisted nematic (TN) type, or a super twisted nematic (STN) type. Various types of liquid crystal cells such as simple matrix drive type can be used. Among these, the TN cell, the VA (Vertical Alignment) cell, and the OCB (Optically Aligned Birefringence) cell are particularly excellent in optical compensation, so that the optical film of the present invention is suitable for a liquid crystal display device including these liquid crystal cells. Very useful.

  In addition, the liquid crystal cell has a structure in which liquid crystal is usually injected into a gap between opposing liquid crystal cell substrates, and the liquid crystal cell substrate is not particularly limited, and for example, a glass substrate or a plastic substrate can be used. The material for the plastic substrate is not particularly limited, and conventionally known materials can be used.

  The laminated polarizing plate of the present invention is not limited to the liquid crystal display device as described above, and can be used for, for example, a self-luminous display device such as an organic electroluminescence (EL) display, PDP, or FED.

  Hereinafter, the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited to the following Examples. The characteristics of the laminated polarizing plate were evaluated by the following methods.

(Measurement of cut surface ridges)
About the 10 mm x 11 mm laminated polarizing plate, the thickness near the center and the cut surface was measured with a micrometer.

(Measurement of protrusion on cut surface)
Using a laser microscope or an optical microscope, the length of the protrusion generated on the cut surface (b in FIG. 2) along the absorption axis of the laminated polarizing plate was measured.

(Measurement of waviness of cut surface of laminated polarizing plate)
Using a laser microscope, the thickness in the vicinity of the cut surface (b in FIG. 2) along the absorption axis of the laminated polarizing plate was measured, and the waviness of the cut surface was calculated using the following equation.
(Wave of cut surface) = (Maximum thickness of cut surface) − (Minimum value of thickness of cut surface)

Example 1
(Preparation of polarizing plate)
First, a polyvinyl alcohol film (thickness 80 μm) was stretched 5 times in an aqueous iodine solution and dried to prepare a polarizer. Subsequently, a UV urethane hard coat layer having a reflectance of 1% or less and a physical optical thin film (AR layer) were formed in this order on one side of a triacetyl cellulose film (TAC film). Then, the treated TAC film was laminated on one side of the polarizer and the untreated TAC film was laminated on the other side of the polarizer via an adhesive to prepare a polarizing plate (thickness: 195 μm, light Transmission 45%).

(Production of resin film)
100 parts by weight of 3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate, 120 parts by weight of methyltetrahydrophthalic anhydride as a curing agent, and tetra-n-butylphosphonium O, O-diethyl phosphoroyl as a curing accelerator 2 parts by weight of dithioate were added and mixed by stirring, and a prefilm (thickness: 600 μm) was formed using a casting method. Further, the prefilm was thermally cured at 180 ° C. for 30 minutes to produce an epoxy film (thickness 700 μm, 380 mm × 280 mm). Subsequently, an acrylic urethane UV resin was applied to one side of the epoxy film to form a protective layer (thickness 3 μm), thereby obtaining a resin film. The light transmittance of this resin film was 91.7%, and the glass transition temperature was 180 ° C.

(Adhesive preparation)
100 parts by weight of butyl acrylate, 5.0 parts by weight of acrylic acid, 0.075 parts by weight of 2-hydroxyethyl acrylate, 0.3 parts by weight of azobisisonitrile and 250 parts by weight of ethyl acetate are mixed and stirred. However, the reaction was carried out at about 60 ° C. for 6 hours to obtain an acrylic polymer solution having a weight average molecular weight of 1,630,000. In the acrylic polymer solution, 0.6 parts by weight of an isocyanate polyfunctional compound (trade name Coronate L; manufactured by Nippon Polyurethane Industry Co., Ltd.) and a silane coupling agent (trade name KBM403) with respect to 100 parts by weight of the polymer solid content. ; Manufactured by Shin-Etsu Chemical Co., Ltd.) and 0.08 part by weight were added to prepare an adhesive solution. The 90 ° peel peel strength of the obtained adhesive solution was 10 N / 25 mm.

(Surface protection sheet production)
The pressure-sensitive adhesive was applied to a thickness of 10 μm on a PET film (thickness 50 μm) and dried to obtain a surface protective sheet.

(Laminated polarizing plate production)
The untreated TAC film side of the polarizing plate was bonded to the epoxy film side of the resin film via the adhesive (thickness 23 μm). The said surface protection sheet was bonded together by the said adhesive on both surfaces of this laminated body.

(Cutting method)
Using a precision-processed CO ₂ laser (trade name SILAS-SAM (SPL2305 type); manufactured by Sugaya Kogyo) under the conditions of an output of 190 W, a conveying speed of 250 mm / s, and an air assist gas pressure of 0.1 MPa, Laser was irradiated from the film side and cut along the absorption axis direction. First, the absorption shaft side was cut. Furthermore, the surface protection sheet affixed on both surfaces of the said laminated body was peeled, and the new surface protection sheet was affixed on both surfaces of the said laminated body again. And the vertical axis direction was cut | disconnected on the same conditions from the resin film side of the said laminated body. Thereby, a plurality (300 pieces) of 10 × 11 mm laminated polarizing plates adhered to the surface protective sheet in a grid pattern were obtained. The pitch between the laminated polarizing plates was 0.1 mm in the absorption axis direction and about 0.1 mm in the vertical axis direction.

(Cleaning method)
Subsequently, after peeling off the surface protective sheet on the resin film side among the surface protective sheets attached to the laminated polarizing plate, the surface of the resin film is wiped off with an anti-contained cloth containing ethanol, and again on the surface, The surface protection sheet was bonded. Next, the surface protective sheet on the polarizing plate side of the laminated polarizing plate was peeled off, and similarly washed with ethanol.

(Example 2)
A laminated polarizing plate was produced in the same manner as in Example 1 except for the following conditions. First, using a CO ₂ laser (trade name LC-100A; manufactured by Roland Corporation), laser irradiation was performed four times (pitch interval 1 mm) under the conditions of an absorption axis direction of an output of 25 W and a conveyance speed of 100 mm / s. Next, laser irradiation was performed twice in the vertical axis direction under the conditions of an output of 25 W and a conveyance speed of 60 mm / s (pitch interval 0.1 mm).

(Comparative Example 1)
A laminated polarizing plate was produced in the same manner as in Example 1 except that laser irradiation was performed on the polarizing plate side of the laminate.

(Comparative Example 2)
A laminated polarizing plate was produced in the same manner as in Example 2 except that laser irradiation was performed on the polarizing plate side of the laminate.

The raised surface of the cut surface and the length of the projections of the laminated polarizing plates obtained in the examples and comparative examples, and the waviness of the cut surface were measured. The results are shown in Table 1 below.
(Table 1)
Bump of cut surface Length of protrusion Waviness of cut surface
(Μm) (μm) (μm)
Example 1 10 25 40
Example 2 30 40 50
Comparative Example 1 20 50 60
Comparative Example 2 50 60 90

  As shown in Table 1, Example 1 is less than the corresponding Comparative Example 1, and Example 2 is less than the corresponding Comparative Example 2. It became.

  According to the production method of the present invention, it is possible to suppress the generation of protrusions on the cut surface even by laser irradiation, and to obtain the laminated polarizing plate of the present invention having sufficient strength. Therefore, the laminated polarizing plate of the present invention is useful for an image display device, and is particularly suitable for a viewfinder or projector in which it is preferable to dispose a polarizing plate at a distance from an image display cell such as a liquid crystal cell. .

In an example of the manufacturing method of the laminated polarizing plate of this invention, it is sectional drawing which shows the outline which performs laser irradiation to the laminated body of a polarizing plate and a resin film. It is a top view which shows an example of the laminated polarizing plate of this invention. It is sectional drawing which shows an example of the liquid crystal display device of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Resin film 12 Adhesive layer 13 Polarizing plate 100 Laser irradiation direction 21 Laminated polarizing plate 22 Surface protection sheet 31 Liquid crystal cell 32 Laminated polarizing plate 302 Resin film 303 Polarizing plate 300 Eyepiece direction A Vertical axis B Absorption axis

Claims (9)

  A step of forming a laminate of a polarizing plate and a resin film having a light transmittance of 80% or more and a glass transition temperature of 100 ° C. or more, and irradiating a laser on the resin film side of the laminate And a step of cutting the laminated body. The resin film is an epoxy resin, polyimide resin, polyester resin, methacrylic resin, polycarbonate (PC) resin, polyethylene naphthalate (PEN) resin, polyethylene terephthalate (PET) resin, triacetyl cellulose ( TAC), norbornene-based resin, polyether imide resin, polyamide resin, according to claim 1 comprising the polysulfone-based resin, at least one resin selected from the group consisting of a polyphenylene sulfide resin and polyether sulfone-based resin Production method.   The manufacturing method of Claim 1 or 2 with which the said polarizing plate contains a polarizer and the transparent protective layer arrange | positioned on both surfaces of the said polarizer. The manufacturing method according to claim 3, wherein the transparent protective layer is formed from a cellulosic polymer. The manufacturing method according to claim 3 or 4, wherein the polarizer is prepared by adsorbing a dichroic substance on a PVA-based film, dyeing, crosslinking, stretching, and drying.   The manufacturing method according to claim 3, wherein one of the transparent protective layers further includes a hard coat layer and a physical optical thin film. The laser is CO ₂ It is a laser, The manufacturing method in any one of Claims 1-6. The manufacturing method according to any one of claims 1 to 7, wherein the laser irradiation is performed by one irradiation with an output of 100W to 350W. The manufacturing method according to any one of claims 1 to 7, wherein the laser irradiation is performed by irradiation twice with an output of 50W to 200W.

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