JP5782722B2 - Polarizing plate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a polarizing plate in which a polarizing film made of a polyvinyl alcohol-based resin and a cycloolefin-based resin film are bonded via an adhesive, and a method for producing the same.

  A polarizing plate is usually a transparent resin film, for example, cellulose acetate represented by triacetyl cellulose, with an adhesive on one or both sides of a polarizing film made of a polyvinyl alcohol-based resin in which a dichroic dye is adsorbed and oriented. The film is laminated. This is bonded to a liquid crystal cell with an adhesive via another optical film such as an optical compensation film or a retardation film, if necessary, and becomes a component of a liquid crystal display device.

  Applications of liquid crystal display devices are rapidly expanding as thin display screens such as liquid crystal televisions, liquid crystal monitors, and personal computers. In particular, the market for liquid crystal televisions has been remarkably expanded, and the demand for cost reduction is very strong. Conventionally, a polarizing plate for a liquid crystal television has been obtained by laminating a triacetyl cellulose film with a water-based adhesive on both sides of a polarizing film made of a polyvinyl alcohol resin, and the polarizing plate is placed on one side of the polarizing plate via an adhesive. A phase difference film was laminated. The retardation film laminated on the polarizing plate uses a stretched product of a polycarbonate resin film or a stretched product of a cycloolefin resin film. Retardation films composed of very few cycloolefin resin films are frequently used. For pasted products of polarizing plates and retardation films made of stretched cycloolefin-based resin films, improvements have been made to reduce the number of components and simplify the manufacturing process in order to improve productivity and reduce product costs. It is being advanced. For example, Japanese Patent No. 3807511 (Patent Document 1) discloses a laminated structure of a cycloolefin-based (norbornene-based) resin film / polarizing film / triacetylcellulose film having a retardation function.

  JP-A-2005-70140 (Patent Document 2), JP-A-4432487 (Patent Document 3) and JP-A-2005-208456 (Patent Document 4) disclose a polyvinyl alcohol polarizing film and a cycloolefin-based film. It is described that a resin film is bonded with a urethane-based aqueous adhesive. On the other hand, Japanese Patent No. 4306270 (Patent Document 5) discloses an active energy ray containing an epoxy compound when a protective film having a low moisture permeability such as a cycloolefin resin film is bonded to a polyvinyl alcohol polarizing film. The use of a curable adhesive is described.

  However, when a water-based adhesive is used for laminating a polyvinyl alcohol polarizing film and a cycloolefin resin film, the adhesive force between the two is not always sufficient, for example, at the interface between the polarizing film and the cycloolefin resin film. It sometimes peeled off. Therefore, after placing the polarizing plate on the liquid crystal cell, if it is necessary to reattach the polarizing plate due to a failure of the polarizing plate (called rework), the adhesive that bonds the polarizing plate and the liquid crystal cell Compared to the adhesive strength, the adhesive strength in the laminated structure of the polarizing plate (for example, the adhesive strength between the polarizing film and the cycloolefin-based resin film) becomes relatively small. There was a problem that only the olefinic resin remained, and the liquid crystal cell could not be reused.

  Further, JP 2006-171707 A (Patent Document 6) discloses cycloolefin in order to firmly bond a polyvinyl alcohol polarizing film and a cycloolefin resin film even when an aqueous adhesive is used. It describes that an easy-adhesion layer containing a silane compound having a reactive functional group is formed on a resin-based resin film, and a polyvinyl alcohol polarizing film is bonded thereto via an adhesive.

Japanese Patent No. 3807511 (JP-A-8-43812) JP-A-2005-70140 Japanese Patent No. 4432487 (Japanese Patent Laid-Open No. 2005-181817) JP-A-2005-208456 Japanese Patent No. 4306270 (Japanese Patent Laid-Open No. 2004-245925) JP 2006-171707 A

  An object of the present invention is to provide a polarizing film in which a cycloolefin resin film is bonded to a polarizing film made of a polyvinyl alcohol resin via an adhesive, and an adhesive force between the polarizing film and the cycloolefin resin film. Is to increase.

  That is, according to the present invention, a polarizing film having a dichroic dye adsorbed and oriented on a polyvinyl alcohol-based resin and a cycloolefin-based resin film laminated on the surface thereof are provided at the interface between them. A polarizing plate in which a primer layer made of a cycloolefin-based resin and an adhesive layer are interposed is provided in this order from the film side.

  In this polarizing plate, the cycloolefin-based resin film is laminated on one surface of the polarizing film via the primer layer and the adhesive layer, and the other surface of the polarizing film is interposed via the adhesive layer. Thus, a protective film made of a thermoplastic resin can be laminated. In these polarizing plates, the primer layer preferably has a thickness of 1 μm or less.

  Further, according to the present invention, a polarizing film is produced by laminating a cycloolefin resin film via an adhesive to a polarizing film having a dichroic dye adsorbed and oriented on a polyvinyl alcohol resin. Then, a cycloolefin resin solvent solution is applied to the surface of the cycloolefin resin film to form a primer layer, and then the surface on which the primer layer is formed is bonded to the polarizing film through an adhesive. A method for manufacturing a polarizing plate is also provided.

  In this production method, a cycloolefin-based resin film on which a primer layer is formed is bonded to one surface of a polarizing film via an adhesive, and the other surface of the polarizing film is bonded to a thermoplastic resin via an adhesive. The protective film which consists of can be bonded. Also, an adhesive for bonding the cycloolefin-based resin film on which the primer layer is formed to one surface of the polarizing film and a protective film made of a thermoplastic resin are bonded to the other surface of the polarizing film. For this purpose, the adhesive may be of the same type, and in this case, it is composed of a cycloolefin resin film bonded to one surface of the polarizing film and a thermoplastic resin to the other surface of the polarizing film. Bonding of the protective film can be performed at the same time.

  The polarizing plate of the present invention has a layer structure in which a polarizing film having a dichroic dye adsorbed and oriented on a polyvinyl alcohol resin / adhesive layer / primer layer composed of a cycloolefin resin / cycloolefin resin film is laminated in this order. In particular, the adhesion between the polarizing film and the cycloolefin-based resin film is enhanced by the presence of the primer layer. Moreover, according to the manufacturing method of this invention, the polarizing plate with which the adhesive force of a polarizing film and a cycloolefin type-resin film was improved can be manufactured advantageously.

It is a cross-sectional schematic diagram which shows the basic layer structure of the polarizing plate which concerns on this invention. It is a cross-sectional schematic diagram which shows the example of the preferable layer structure of the polarizing plate which concerns on this invention.

  The polarizing plate of the present invention is obtained by laminating a cycloolefin-based resin film 3 on a polarizing film 1 in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin with reference to FIG. And in both interfaces, the primer layer 4 and the adhesive bond layer 8 which consist of cycloolefin resin in order from the cycloolefin resin film 3 side intervene. The cycloolefin resin film 3 may be bonded to at least one surface of the polarizing film 1, and of course, may be bonded to both surfaces of the polarizing film 1. When the cycloolefin-based resin film 3 is bonded to one side of the polarizing film 1, as shown in FIG. 2, a protective film 6 made of another thermoplastic resin is also placed on the opposite side through the adhesive layer 9. It is preferable to paste. First, each component of the polarizing plate according to the present invention will be described.

[Polarized film]
In the polarizing film used in the present invention, a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin. By uniaxially stretching the polyvinyl alcohol-based resin film before, during or after the adsorption of the dichroic dye, the dichroic dye can be oriented in the stretching direction. The polyvinyl alcohol resin can be obtained by saponifying a polyvinyl acetate resin. 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, such as ethylene-vinyl acetate copolymer. Etc. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins including ethylene, vinyl ethers, and acrylamides having an ammonium group.

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

  A film obtained by forming such a polyvinyl alcohol resin is used as a raw film of a polarizing film. The method for forming the polyvinyl alcohol-based resin is not particularly limited, and can be formed by a conventionally known appropriate method. Although the film thickness of the raw film which consists of polyvinyl alcohol-type resin is not specifically limited, For example, it is about 10 micrometers-150 micrometers.

  A polarizing film usually includes a process of dyeing a polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye (dyeing process), and a polyvinyl alcohol resin film on which the dichroic dye is adsorbed. It is manufactured through a step of treating with an acid aqueous solution (boric acid treatment step) and a step of washing with water after the treatment with the boric acid aqueous solution (water washing treatment step).

  In addition, in the production of the polarizing film, the polyvinyl alcohol-based resin film is uniaxially stretched, but this uniaxial stretching may be performed before the dyeing process, or may be performed during the dyeing process, or the dyeing process. It may be performed after the process. When uniaxial stretching is performed after the dyeing treatment step, this uniaxial stretching may be performed before the boric acid treatment step or during the boric acid treatment step. Of course, it is also possible to perform uniaxial stretching in these plural stages. Uniaxial stretching may be performed by passing between spaced apart rolls having different peripheral speeds, or may be performed by a method of sandwiching with hot rolls. Moreover, the dry-type extending | stretching which extends | stretches in air | atmosphere may be sufficient, and the wet extending | stretching which extends | stretches in the state swollen with the solvent may be sufficient. The draw ratio is usually about 3 to 8 times.

  The polyvinyl alcohol resin film is dyed with a dichroic dye, for example, by immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye. As the dichroic dye, for example, iodine or a dichroic organic dye is used. Examples of the dichroic organic dye include dichroic direct dyes composed of disazo compounds such as C.I. DIRECT RED 39, and dichroic direct dyes composed of compounds such as trisazo and tetrakisazo. 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 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually 0.5 to 20 parts by weight per 100 parts by weight of water. Parts by weight. When iodine is used as the dichroic dye, the temperature of the aqueous solution used for dyeing is usually 20 ° C to 40 ° C, and the immersion time (dyeing time) in this aqueous solution is usually 20 seconds to 1,800 seconds. It is.

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 1 × 10 ⁻⁴ parts by weight to 10 parts by weight, preferably 1 × 10 ⁻³ parts by weight to 1 part by weight, more preferably 100 parts by weight of water. Is 1 × 10 ⁻³ parts by weight to 1 × 10 ⁻² parts by weight. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. When a dichroic organic dye is used as the dichroic dye, the temperature of the aqueous dye solution used for dyeing is usually 20 ° C to 80 ° C, and the immersion time (dyeing time) in this aqueous solution is usually 10 ° C. Seconds to 1,800 seconds.

  The boric acid treatment step is performed by immersing a polyvinyl alcohol-based resin film dyed with a dichroic dye in a boric acid-containing aqueous solution. The amount of boric acid in the boric acid-containing aqueous solution is usually 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 in the dyeing process described above, the boric acid-containing aqueous solution used in this boric acid treatment process preferably contains potassium iodide. In this case, the content of potassium iodide in the boric acid-containing aqueous solution is usually 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 60 seconds to 1,200 seconds, preferably 150 seconds to 600 seconds, and more preferably 200 seconds to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 ° C. to 85 ° C., more preferably 60 ° C. to 80 ° C.

  In the subsequent washing process, the polyvinyl alcohol-based resin film after the boric acid treatment described above is washed with water, for example, by immersing it in water. The water temperature in the water washing treatment is usually 5 ° C. to 40 ° C., and the immersion time is usually 1 second to 120 seconds. After the water washing treatment, usually a drying treatment is performed to obtain a polarizing film. The drying process can be performed using, for example, a hot air dryer or a far infrared heater. The temperature of the drying treatment is usually 30 ° C to 100 ° C, preferably 50 ° C to 80 ° C. The time for the drying treatment is usually 60 seconds to 600 seconds, preferably 120 seconds to 600 seconds.

  As described above, it is possible to produce a polarizing film in which a dichroic dye is adsorbed and oriented on a uniaxially stretched polyvinyl alcohol resin film. The thickness of the polarizing film can be about 5 μm to 40 μm.

[Cycloolefin resin film]
In this invention, the protective film provided in at least one surface of a polarizing film is comprised with a cycloolefin type resin film, and the cycloolefin type resin film is bonded to a polarizing film through an adhesive agent.

  The cycloolefin-based resin is a thermoplastic resin having a monomer unit made of a cyclic olefin (cycloolefin) such as norbornene or a polycyclic norbornene-based monomer, and is also called a thermoplastic cycloolefin-based resin. The cycloolefin-based resin may be a hydrogenated product of the above-mentioned cycloolefin ring-opening polymer or a ring-opening copolymer using two or more kinds of cycloolefins. Cycloolefin, chain olefin, vinyl It may be an addition polymer with an aromatic compound having a polymerizable double bond such as a group. A polar group may be introduced into the cycloolefin resin.

  When the protective film is composed of a copolymer of a cycloolefin and a chain olefin and / or an aromatic compound having a vinyl group, ethylene, propylene, or the like is used as the chain olefin, and an aromatic group having a vinyl group. Examples of group compounds include styrene, α-methylstyrene, and nuclear alkyl-substituted styrene. In such a copolymer, the monomer unit composed of cycloolefin may be 50 mol% or less, but is preferably about 15 to 50 mol%. In particular, when a terpolymer of a cycloolefin, a chain olefin, and an aromatic compound having a vinyl group is used as a protective film, the monomer unit composed of a cycloolefin may have a relatively small amount as described above. it can. In such a terpolymer, the monomer unit composed of a chain olefin is usually 5 to 80 mol%, and the monomer unit composed of an aromatic compound having a vinyl group is usually 5 to 80 mol%.

For the cycloolefin resin film, an appropriate commercial product can be used. For example, “TOPAS” produced by TOPAS ADVANCED POLYMERS GmbH in Germany and sold by Polyplastics Co., Ltd. in Japan, JSR Co., Ltd. "Arton" have been sold from, Nippon Zeon has been sold from the (stock) "ZEONOR" (ZEONOR) and "Zeonex" (ZEONEX), include "APEL", etc. are available from Mitsui Chemicals, Inc. be able to. In order to form such a cycloolefin-based resin into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used. Also, for example, “Essina” and “SCA40” sold by Sekisui Chemical Co., Ltd., “Zeonor Film” sold by Nippon Zeon Co., Ltd., “Arton Film” sold by JSR Co., Ltd. A commercial product of a pre-formed cycloolefin-based resin film such as “ (all are trade names) ” may be used.

  The cycloolefin resin film may be stretched and provided with a phase difference. Stretching can be performed by uniaxial stretching or biaxial stretching. In this case, the draw ratio is usually 1.1 to 5 times, preferably 1.1 to 3 times. The stretched cycloolefin-based resin film is preferably thin, but if it is too thin, the strength tends to decrease and the processability tends to be poor. On the other hand, if it is too thick, the transparency decreases and the weight of the polarizing plate increases. There is a tendency to become. From such a viewpoint, the thickness of the cycloolefin-based resin film is usually 5 μm to 200 μm, preferably 10 μm to 150 μm, more preferably 20 μm to 100 μm.

[Primer layer]
At the interface between the polarizing film 1 and the cycloolefin resin film 3, a primer layer 4 and an adhesive layer 8 made of a cycloolefin resin are interposed in this order from the cycloolefin resin film 3 side. Thus, by interposing the primer layer 4 between the cycloolefin-based resin film 3 and the adhesive layer 8, the adhesiveness between the polarizing film 1 and the cycloolefin-based resin film 3 is improved.

  The primer layer 4 can be formed by coating a resin composition containing a cycloolefin resin on the cycloolefin resin film 3 and then performing a drying treatment. The resin composition used for forming the primer layer 4 can be a solvent solution of a cycloolefin resin. Specifically, a resin composition containing a cycloolefin resin and an organic solvent in which the cycloolefin resin is soluble as a main solvent (hereinafter also referred to as “primer coating solution”) is preferably used.

  The cycloolefin resin contained in the primer coating solution is not particularly limited, and the various cycloolefin resins described above can be used. Generally, the cycloolefin resin on which the primer layer 4 is formed is used. A resin of the same kind as the film 3 is preferable.

  The organic solvent used as the main solvent is not particularly limited as long as it can dissolve the cycloolefin resin. For example, halogenated hydrocarbon solvents such as dichloromethane and chloroform, aromatics such as toluene and xylene, and the like. Solvents, ketone solvents such as methyl isobutyl ketone and cyclohexanone, ether solvents such as diethyl ether and tetrahydrofuran, hydrocarbon solvents such as n-pentane, n-hexane, n-heptane, and cyclohexane, isopropanol and Examples thereof include alcohol solvents such as n-butanol and ester solvents such as ethyl acetate and butyl acetate. These solvents may be used alone or in combination of two or more.

  The primer coating solution may contain various additives in addition to the cycloolefin resin. Examples of additives that can be used include phenolic stabilizers, phosphite stabilizers, amine stabilizers, amide stabilizers, anti-aging agents, weathering stabilizers, antisettling agents, antioxidants, and heat stability. Agents, and various stabilizers such as light stabilizers; thixotropic agents, thickeners, antifoaming agents, surface conditioners, weathering agents, pigment dispersants, antistatic agents, lubricants, nucleating agents, flame retardants, oil agents, And various performance modifiers such as dyes; pigments made of transition metal compounds such as titanium oxide (rutile type) and zinc oxide and carbon black; glass fibers, carbon fibers, potassium titanate fibers, wollastonite, calcium carbonate , Calcium sulfate, talc, glass flake, barium sulfate, clay, kaolin, fine powder silica, mica, calcium silicate, aluminum hydroxide, magnesium hydroxide, aluminum oxide, oxidation Magnesium, and the like fillers such as diatomaceous earth.

  The thickness of the primer layer 4 is not particularly limited as long as the primer layer is interposed, but if it is too thick, the phase difference to be brought about by the cycloolefin-based resin film 3 is changed, and the polarization is changed. The effect of reducing the thickness and weight of the plate is reduced. Therefore, the thickness of the primer layer 4 is preferably 5 μm or less, more preferably 2 μm or less, and particularly preferably 1 μm or less. The thickness of the primer layer 4 obtained by application of the primer coating liquid and subsequent drying can be adjusted by selecting a coating method, selecting a coater used for coating, selecting a concentration of the primer coating liquid, and the like.

  The adhesive layer 4 for attaching the polarizing film 1 and the cycloolefin-based resin film 3 is formed using an adhesive as described in detail below. When adhering these films using an adhesive, the primer layer 4 formed on the adhesive surface of the polarizing film 1 and / or the cycloolefin-based resin film 3 bonded thereto in order to improve the adhesiveness. In addition, surface treatment such as plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, and saponification treatment may be appropriately performed. Hereinafter, the adhesive used for adhering the polarizing film and the cycloolefin-based resin film will be described.

[adhesive]
An adhesive is used for adhering the polarizing film 1 and the cycloolefin-based resin film 3. Under the present circumstances, it laminates | stacks so that it may become the primer layer 4, the adhesive bond layer 8, and the polarizing film 1 which consist of cycloolefin resin sequentially from the cycloolefin resin film 3 side. The adhesive used for this purpose only needs to express adhesive force to both the polarizing film 1 and the cycloolefin-based resin film 3 or the primer layer 4 formed thereon. Examples thereof include a water-based adhesive dissolved or dispersed in water and a curable adhesive containing an active energy ray-curable compound. Considering that the surface of the polarizing film is hydrophilic, an aqueous adhesive in which an adhesive component is dissolved or dispersed in water is preferable. The water-based adhesive is also preferable from the viewpoint of thinning the cured adhesive layer. Examples of the adhesive component that is the main component of the water-based adhesive include polyvinyl alcohol resins and urethane resins.

  When a polyvinyl alcohol resin is used as the main component of the aqueous adhesive, the polyvinyl alcohol resin can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include, in addition to polyvinyl acetate, which is a homopolymer of vinyl acetate, copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerized with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, and acrylamides having an ammonium group. The polyvinyl alcohol resin used for the adhesive preferably has an appropriate degree of polymerization. For example, when a polyvinyl alcohol-based resin aqueous solution having a concentration of 4% by weight is used, the viscosity is within a range of 4 mPa · sec to 50 mPa · sec, and further within a range of 6 mPa · sec to 30 mPa · sec at 25 ° C. It is preferable.

  The saponification degree of the polyvinyl alcohol-based resin used for the adhesive is not particularly limited, but is generally preferably 80 mol% or more, and more preferably 90 mol% or more. If the degree of saponification of the polyvinyl alcohol resin used for the adhesive is low, the water resistance of the resulting adhesive layer tends to be insufficient.

  For the adhesive, a modified polyvinyl alcohol-based resin is preferably used. Suitable modified polyvinyl alcohol resins include acetoacetyl group-modified polyvinyl alcohol resins, anion-modified polyvinyl alcohol resins, and cation-modified polyvinyl alcohol resins. If such a modified polyvinyl alcohol resin is used, the effect of improving the water resistance of the adhesive layer can be easily obtained.

The acetoacetyl group-modified polyvinyl alcohol resin has an acetoacetyl group (CH ₃ COCH ₂ CO—) in addition to the hydroxyl group constituting the polyvinyl alcohol skeleton, and has other groups such as an acetyl group. You may do it. This acetoacetyl group typically exists in a state in which a hydrogen atom of a hydroxyl group constituting polyvinyl alcohol is substituted. An acetoacetyl group-modified polyvinyl alcohol resin can be produced, for example, by a method of reacting polyvinyl alcohol with diketene. The acetoacetyl group-modified polyvinyl alcohol-based resin has an acetoacetyl group that is a highly reactive functional group, and thus is preferable for improving the durability of the adhesive layer.

  The content of the acetoacetyl group in the polyvinyl alcohol resin modified with acetoacetyl group is not particularly limited as long as it is 0.1 mol% or more. The content of the acetoacetyl group here is a value in which the mole fraction of the acetoacetyl group relative to the total amount of the hydroxyl group, acetoacetyl group, and other ester groups (acetyl group, etc.) in the polyvinyl alcohol resin is expressed in%. And may be referred to as “degree of acetoacetylation”. When the degree of acetoacetylation in the polyvinyl alcohol-based resin is less than 0.1 mol%, the effect of improving the water resistance of the adhesive layer is not always sufficient. The degree of acetoacetylation in the polyvinyl alcohol-based resin is preferably about 0.1 mol% to 40 mol%, more preferably 1 mol% to 20 mol%, and particularly preferably 2 mol% to 7 mol%. When the degree of acetoacetylation exceeds 40 mol%, the effect of improving water resistance becomes small.

  An anion-modified polyvinyl alcohol-based resin contains an anionic group, typically a carboxyl group (—COOH) or a salt thereof, in addition to the hydroxyl group constituting the polyvinyl alcohol skeleton. It may have an acetyl group or the like. An anion-modified polyvinyl alcohol resin can be produced, for example, by a method in which an unsaturated monomer having an anionic group (typically a carboxyl group) is copolymerized with vinyl acetate and then saponified. . On the other hand, a cation-modified polyvinyl alcohol-based resin contains a cationic group, typically a tertiary amino group or a quaternary ammonium group, in addition to the hydroxyl group constituting the polyvinyl alcohol skeleton. For example, it may have an acetyl group. The cation-modified polyvinyl alcohol resin is, for example, a method in which an unsaturated monomer having a cationic group (typically a tertiary amino group or a quaternary ammonium group) is copolymerized with vinyl acetate and then saponified. Can be manufactured.

  Of course, the adhesive used in the present invention may contain two or more of the above-mentioned modified polyvinyl alcohol-based resins, and may also be an unmodified polyvinyl alcohol-based resin (specifically, It may contain both a partially saponified product) and the above-described modified polyvinyl alcohol resin.

  The polyvinyl alcohol-based resin constituting the adhesive can be used by appropriately selecting from commercially available products. Specifically, for example, polyvinyl alcohol having a high degree of saponification, such as “PVA-117H” sold by Kuraray Co., Ltd. and “Gosenol NH” sold by Nippon Synthetic Chemical Industry Co., Ltd. -20 ", polyvinyl alcohol modified with acetoacetyl group," Gosefimer Z "series sold by Nippon Synthetic Chemical Industry Co., Ltd., anion-modified polyvinyl alcohol, Kuraray Co., Ltd. "KL-318" and "KM-118" sold by KK, "Gosenal T-330" sold by Nippon Synthetic Chemical Industry Co., Ltd., cation-modified polyvinyl alcohol, Examples include “CM-318” sold by Kuraray and “Gosefimer K-210” sold by Nippon Synthetic Chemical Industry.

  The concentration of the polyvinyl alcohol resin in the adhesive is not particularly limited, but since it is used in the form of an aqueous solution, the polyvinyl alcohol resin is in the range of 1 to 20 parts by weight with respect to 100 parts by weight of water. In particular, it is more preferably 1 to 15 parts by weight, more preferably 1 to 10 parts by weight, especially 2 to 10 parts by weight. If the concentration of the polyvinyl alcohol-based resin in the aqueous solution is too small, the adhesiveness tends to decrease. On the other hand, if the concentration is too large, the optical properties of the resulting polarizing plate tend to decrease. The water used for the adhesive can be pure water, ultrapure water, tap water, etc., and is not particularly limited. However, from the viewpoint of maintaining the uniformity and transparency of the formed adhesive layer, Water or ultrapure water is preferred. Alcohols such as methanol and ethanol can also be added to the adhesive aqueous solution.

  A water-based adhesive mainly composed of a polyvinyl alcohol resin can contain a crosslinking agent. The cross-linking agent may be a compound having a functional group having reactivity with a polyvinyl alcohol resin, and those conventionally used in polyvinyl alcohol adhesives can be used without particular limitation. When compounds capable of forming a crosslinking agent are listed by functional group, an isocyanate compound having at least two isocyanato groups (—NCO) in the molecule; an epoxy compound having at least two epoxy groups (crosslinked —O—) in the molecule; Mono- or di-aldehydes; organic titanium compounds; inorganic salts of divalent or trivalent metals such as magnesium, calcium, iron, nickel, zinc, and aluminum; metal salts of glyoxylic acid; methylol melamine;

  Specific examples of the isocyanate compound used as the crosslinking agent include tolylene diisocyanate, hydrogenated tolylene diisocyanate, adducts of trimethylolpropane and tolylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, isophorone diisocyanate, and ketoximes thereof. A block thing or a phenol block thing etc. are mentioned.

  Specific examples of the epoxy compound serving as a crosslinking agent include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, di- or tri-glycidyl ether of glycerin, 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether. , Diglycidyl aniline, diglycidyl amine, water-soluble polyamide epoxy resin obtained by reacting epichlorohydrin with polyamide polyamine which is a reaction product of polyalkylene polyamine and dicarboxylic acid.

  Specific examples of monoaldehydes that serve as crosslinking agents include formaldehyde, acetaldehyde, propionaldehyde, butyraldehyde, and specific examples of dialdehydes include glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, Maleic dialdehyde, phthaldialdehyde and the like can be mentioned.

  Various organic titanium compounds that serve as crosslinking agents are sold by Matsumoto Fine Chemical Co., Ltd. It is suitable for the present invention from the company's home page related to organic titanium compounds (Internet <URL: http://www.m-chem.co.jp/products/products1.html>, searched on January 25, 2011) The water-soluble organotitanium compounds used are listed below in the order of their formula, chemical name, and product name.

[(CH ₃ ) ₂ CHO] ₂ Ti [OCH ₂ CH ₂ N (CH ₂ CH ₂ OH) ₂ ] ₂ : Chemical name "Titanium diisopropoxybis (triethanolaminate)", the company's product name “Orgachicks TC-400”,
(HO) ₂ Ti [OCH (CH ₃ ) COO ⁻ ] ₂ (NH ₄ ⁺ ) ₂ : Chemical name “Titanium lactate ammonium salt”, the company's product name “OrgaTix TC-300”,
(HO) ₂ Ti [OCH (CH ₃ ) COOH] ₂ : Chemical name “titanium lactate”, the company name “Orgachix TC-310” and “Orgachix TC-315”.

  The metal salt of glyoxylic acid is preferably an alkali metal salt or an alkaline earth metal salt, and examples thereof include sodium glyoxylate, potassium glyoxylate, magnesium glyoxylate, and calcium glyoxylate.

  Among these crosslinking agents, epoxy compounds including the above-mentioned water-soluble polyamide epoxy resins, aldehydes, methylol melamine, alkali metal or alkaline earth metal salts of glyoxylic acid, and the like are preferably used.

  The crosslinking agent is preferably dissolved in water together with the polyvinyl alcohol resin to form an adhesive. However, since the amount of the crosslinking agent in the aqueous solution may be small as described below, any crosslinking agent having a solubility of at least about 0.1% by weight in water can be used. Of course, a compound having a solubility in water of a level generally called water solubility is more suitable as a crosslinking agent used in the present invention.

  The amount of the crosslinking agent is appropriately designed according to the type of the polyvinyl alcohol resin and the like, but is usually about 5 to 60 parts by weight, preferably 10 parts per 100 parts by weight of the polyvinyl alcohol resin. Parts by weight to 50 parts by weight. By blending the cross-linking agent within this range, good adhesiveness can be obtained. As described above, in order to improve the durability of the adhesive layer, an acetoacetyl group-modified polyvinyl alcohol-based resin is preferably used. In this case as well, crosslinking is performed with respect to 100 parts by weight of the polyvinyl alcohol-based resin. It is preferable to blend the agent at a ratio of 5 to 60 parts by weight, and further 10 to 50 parts by weight. If the amount of the cross-linking agent is too large, the reaction of the cross-linking agent proceeds in a short time and the adhesive tends to gel early, resulting in extremely short pot life and industrial use. It becomes difficult.

  The adhesive may be blended with conventionally known appropriate additives such as a silane coupling agent, a plasticizer, an antistatic agent, and fine particles as long as the effects of the present invention are not impaired.

  When a urethane resin is used as the main component of the water-based adhesive, an example of a suitable adhesive is a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group. 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. Such an ionomer type urethane resin is suitably used for an aqueous adhesive because it is emulsified directly in water without using an emulsifier to form an emulsion. The use of a polyester ionomer type urethane resin as an adhesive for a polarizing film and a protective film is, for example, disclosed in Patent Document 2 (Japanese Patent Laid-Open No. 2005-070140), Patent Document 3 (Japanese Patent No. 4432487), and Patent Document 4 (Japanese Patent Laid-Open No. 2005-208456).

  A curable adhesive containing an active energy ray-curable compound can also be used for adhering the polarizing film 1 and the cycloolefin-based resin film 3. The “active energy ray-curable compound” means a compound that can be cured by irradiation with active energy rays. The active energy ray-curable compound may be cationically polymerizable or radically polymerizable. Examples of the cationic polymerizable compound include an epoxy compound having at least one epoxy group in the molecule, an oxetane compound having at least one oxetane ring in the molecule, and the like. Examples of the radical polymerizable compound include (meth) acrylic compounds having at least one (meth) acryloyloxy group in the molecule. The “(meth) acryloyloxy group” means an acryloyloxy group or a methacryloyloxy group.

  The active energy ray-curable compound used for the sticking preferably includes at least an epoxy compound, and thereby exhibits good adhesion between the polarizing film 1 and the cycloolefin-based resin film 3.

  As an epoxy compound, it is preferable to use the epoxy compound which does not contain an aromatic ring in a molecule | numerator from a viewpoint of a weather resistance, a refractive index, cationic polymerization, etc. as a main component. Examples of the epoxy compound that does not contain an aromatic ring in the molecule include glycidyl ether of a polyol having an alicyclic ring, an aliphatic epoxy compound, and an alicyclic epoxy compound. The epoxy compound suitably used for such a curable adhesive is described in detail in, for example, the above-mentioned Patent Document 5 (Patent No. 4306270), but the outline is also described here.

  The glycidyl ether of a polyol having an alicyclic ring is a glycidyl etherification of a nuclear hydrogenated polyhydroxy compound obtained by selectively hydrogenating an aromatic polyol under pressure in the presence of a catalyst. Can be. Examples of the aromatic polyol include bisphenol type compounds such as bisphenol A, bispheel F, and bisphenol S; novolac type resins such as phenol novolac resin, cresol novolac resin, and hydroxybenzaldehyde phenol novolac resin; tetrahydroxydiphenylmethane, Examples thereof include tetrahydroxybenzophenone and polyfunctional compounds such as polyvinylphenol. Glycidyl ether can be obtained by reacting an alicyclic polyol obtained by hydrogenating the aromatic ring of these aromatic polyols with epichlorohydrin. Among these glycidyl ethers of polyols having an alicyclic ring, hydrogenated bisphenol A diglycidyl ether is preferable.

  The aliphatic epoxy compound can be a polyglycidyl ether of an aliphatic polyhydric alcohol or an alkylene oxide adduct thereof. More specifically, 1,4-butanediol diglycidyl ether; 1,6-hexanediol diglycidyl ether; glycerin triglycidyl ether; trimethylolpropane triglycidyl ether; polyethylene glycol diglycidyl ether; propylene Diglycidyl ether of glycol; Polyether polyol obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to an aliphatic polyhydric alcohol such as ethylene glycol, propylene glycol or glycerin Examples thereof include glycidyl ether.

  An alicyclic epoxy compound is a compound having at least one epoxy group bonded to an alicyclic ring in the molecule. Here, the “epoxy group bonded to the alicyclic ring” means a bridged oxygen atom —O— in the structure represented by the following formula, and in this formula, m is an integer of 2 to 5.

A compound in which one or a plurality of hydrogen atoms in (CH ₂ ) _m in this formula are bonded to another chemical structure can be an alicyclic epoxy compound. Further, one or more hydrogen atoms in (CH ₂ ) _m forming the alicyclic ring may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group.

  Among the epoxy compounds as described above, an alicyclic epoxy compound, that is, a compound in which at least one of the epoxy groups is bonded to the alicyclic ring is preferable, and in particular, an oxabicyclohexane ring (in the above formula, m = 3) and an epoxy compound having an oxabicycloheptane ring (m = 4 in the above formula) has a high elastic modulus of the cured product and gives good adhesion between the polarizing film and the protective film. Are more preferably used. Specific examples of the alicyclic epoxy compound are listed below. Here, the compound names are given first, and then the chemical formulas corresponding to each are shown, and the same reference numerals are given to the compound names and the chemical formulas corresponding thereto.

A: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate,
B: 3,4-epoxy-6-methylcyclohexylmethyl 3,4-epoxy-6-methylcyclohexanecarboxylate,
C: ethylene bis (3,4-epoxycyclohexanecarboxylate),
D: Bis (3,4-epoxycyclohexylmethyl) adipate,
E: bis (3,4-epoxy-6-methylcyclohexylmethyl) adipate,
F: Diethylene glycol bis (3,4-epoxycyclohexyl methyl ether),
G: ethylene glycol bis (3,4-epoxycyclohexyl methyl ether),
H: 2,3,14,15-diepoxy-7,11,18,21-tetraoxatrispiro [5.2.2.2.5.2] henicosane,
I: 3- (3,4-epoxycyclohexyl) -8,9-epoxy-1,5-dioxaspiro [5.5] undecane,
J: 4-vinylcyclohexene dioxide,
K: Limonene dioxide
L: bis (2,3-epoxycyclopentyl) ether,
M: Dicyclopentadiene dioxide and the like.

  In the curable adhesive, the epoxy compound may be used alone or in combination of two or more.

  The curable adhesive may contain an oxetane compound in addition to the epoxy compound. By adding an oxetane compound, the viscosity of the curable adhesive can be lowered and the curing speed can be increased.

The oxetane compound is a compound having at least one oxetane ring (four-membered ether) in the molecule, such as 3-ethyl-3-hydroxymethyloxetane, 1,4-bis [(3-ethyl-3 -Oxetanyl) methoxymethyl] benzene, 3-ethyl-3- (phenoxymethyl) oxetane, di [(3-ethyl-3-oxetanyl) methyl] ether, 3-ethyl-3- (2-ethylhexyloxymethyl) oxetane And phenol novolac oxetane. These oxetane compounds can be easily obtained as commercial products. For example, “Aron Oxetane OXT-101” and “Aron Oxetane OXT-” are trade names sold by Toagosei Co., Ltd. 121 ”,“ Aron Oxetane
OXT-211 ”,“ Aron Oxetane OXT-221 ”,“ Aron Oxetane OXT-212 ”, etc. The amount of the oxetane compound is not particularly limited, but it is usually based on the whole active energy ray-curable compound. It is 50 wt% or less, preferably 10 to 40 wt%.

  When the curable adhesive contains a cationically polymerizable compound such as an epoxy compound or an oxetane compound, a photocationic polymerization initiator is usually added to the curable adhesive. When a cationic photopolymerization initiator is used, it is possible to form an adhesive layer at room temperature, reducing the need to consider the heat resistance of the polarizing film and distortion due to expansion, and sticking the polarizing film and the protective film with good adhesion. Yes. Moreover, since a photocationic polymerization initiator acts catalytically with light, even if it is mixed with a curable adhesive, the curable adhesive is excellent in storage stability and workability.

  The cationic photopolymerization initiator generates a cationic species or a Lewis acid by irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, or electron beams, and initiates a polymerization reaction of the cationically polymerizable compound. The photocationic polymerization initiator may be of any type, but specific examples include aromatic diazonium salts; onium salts such as aromatic iodonium salts and aromatic sulfonium salts; iron-allene complexes, etc. There is.

Examples of the aromatic diazonium salt include the following compounds.
Benzenediazonium hexafluoroantimonate,
Benzenediazonium hexafluorophosphate,
Benzenediazonium hexafluoroborate, etc.

Examples of the aromatic iodonium salt include the following compounds.
Diphenyliodonium tetrakis (pentafluorophenyl) borate,
Diphenyliodonium hexafluorophosphate,
Diphenyliodonium hexafluoroantimonate,
Di (4-nonylphenyl) iodonium hexafluorophosphate and the like.

Examples of the aromatic sulfonium salt include the following compounds.
Triphenylsulfonium hexafluorophosphate,
Triphenylsulfonium hexafluoroantimonate,
Triphenylsulfonium tetrakis (pentafluorophenyl) borate,
4,4'-bis [diphenylsulfonio] diphenyl sulfide bishexafluorophosphate,
4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluoroantimonate,
4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenyl sulfide bishexafluorophosphate,
7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate,
7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate,
4-phenylcarbonyl-4'-diphenylsulfonio-diphenyl sulfide hexafluorophosphate,
4- (p-tert-butylphenylcarbonyl) -4'-diphenylsulfonio-diphenyl sulfide hexafluoroantimonate,
4- (p-tert-butylphenylcarbonyl) -4'-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate and the like.

Moreover, as an iron-allene complex, the following compounds are mentioned, for example.
Xylene-cyclopentadienyl iron (II) hexafluoroantimonate,
Cumene-cyclopentadienyl iron (II) hexafluorophosphate,
Xylene-cyclopentadienyl iron (II) tris (trifluoromethylsulfonyl) methanide.

These photocationic polymerization initiators can be easily obtained as commercial products. For example, “Kayarad PCI-220” and “Kayarad PCI-620” sold by Nippon Kayaku Co., Ltd. under the trade names, respectively. "UVI-6990" sold by Union Carbide, "UVACURE 1590" sold by Daicel Cytec, "Adekaoptomer SP-150" sold by ADEKA, and “Adekaoptomer SP-170”, “CI-5102”, “CIT-1370”, “CIT-1682”, “CIP-1866S” sold by Nippon Soda Co., Ltd.,
“CIP-2048S” and “CIP-2064S”, “DPI-101”, “DPI-102”, “DPI-103”, “DPI-105”, “MPI-103” sold by Midori Chemical Co., Ltd. ”,“ MPI-105 ”,“ BBI-101 ”,
“BBI-102”, “BBI-103”, “BBI-105”, “TPS-101”, “TPS-102”, “TPS-103”,
“TPS-105”, “MDS-103”, “MDS-105”, “DTS-102” and “DTS-103”, “PI-2074” sold by Rhodia, and the like.

  These cationic photopolymerization initiators may be used alone or in combination of two or more. Among these, in particular, the aromatic sulfonium salt has an ultraviolet absorption property even in a wavelength region of 300 nm or more, so it has excellent curability, gives good mechanical strength, and is good between the polarizing film and the protective film. Since it can give the hardened | cured material which has adhesiveness, it is used preferably.

The compounding quantity of a photocationic polymerization initiator is 0.5 to 20 weight part normally with respect to a total of 100 weight part of the cationically polymerizable compound containing an epoxy compound and an oxetane compound, Preferably 1 weight part- 6 parts by weight. If the amount of the cationic photopolymerization initiator is small, the curing becomes insufficient, and the mechanical strength and the adhesion between the polarizing film and the protective film tend to be lowered. On the other hand, if the amount of the cationic photopolymerization initiator is too large, the amount of ionic substances in the cured product will increase, resulting in an increase in the hygroscopicity of the cured product, which may reduce the durability of the resulting adhesive layer. is there.

  Moreover, the curable adhesive may contain a radically polymerizable (meth) acrylic compound together with the epoxy compound or together with the epoxy compound and the oxetane compound. By using a (meth) acrylic compound in combination, the effect of increasing the hardness and mechanical strength of the adhesive layer can be expected, and furthermore the adjustment of the viscosity and curing speed of the curable adhesive can be performed more easily. Become.

  The (meth) acrylic compound is obtained by reacting at least one (meth) acrylate monomer having at least one (meth) acryloyloxy group in the molecule or two or more functional group-containing compounds. Examples include (meth) acryloyloxy group-containing compounds such as (meth) acrylate oligomers having a single (meth) acryloyloxy group. These may be used alone or in combination of two or more. When two or more types are used in combination, two or more types of (meth) acrylate monomers may be used, or two or more types of (meth) acrylate oligomers may be used. Of course, one or more types of (meth) acrylate monomers may be used. And one or more (meth) acrylate oligomers may be used in combination. “(Meth) acrylate” means acrylate or methacrylate.

  The above (meth) acrylate monomer includes a monofunctional (meth) acrylate monomer having one (meth) acryloyloxy group in the molecule, and a bifunctional (meth) acrylate having two (meth) acryloyloxy groups in the molecule. ) Acrylate monomers and polyfunctional (meth) acrylate monomers having three or more (meth) acryloyloxy groups in the molecule.

  Specific examples of monofunctional (meth) acrylate monomers include tetrahydrofurfuryl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, 2- or 3-hydroxypropyl (meth) acrylate, and 2-hydroxybutyl (meth) acrylate. 2-hydroxy-3-phenoxypropyl (meth) acrylate, isobutyl (meth) acrylate, tert-butyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, cyclohexyl (meth) acrylate, dicyclopentenyl (meth) acrylate, Benzyl (meth) acrylate, isobornyl (meth) acrylate, phenoxyethyl (meth) acrylate, dicyclopentenyloxyethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate , Ethyl carbitol (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate, phenoxypolyethylene glycol (meth) acrylate, and the like.

  As the monofunctional (meth) acrylate monomer, a carboxyl group-containing (meth) acrylate monomer may be used. Examples of the carboxyl group-containing monofunctional (meth) acrylate monomer include 2- (meth) acryloyloxyethyl phthalic acid, 2- (meth) acryloyloxyethyl hexahydrophthalic acid, carboxyethyl (meth) acrylate, and 2- (meth). Examples include acryloyloxyethyl succinic acid, N- (meth) acryloyloxy-N ′, N′-dicarboxymethyl-p-phenylenediamine, and 4- (meth) acryloyloxyethyl trimellitic acid.

  Bifunctional (meth) acrylate monomers include alkylene glycol di (meth) acrylates, polyoxyalkylene glycol di (meth) acrylates, halogen-substituted alkylene glycol di (meth) acrylates, aliphatic polyol di (meth) acrylates Di (meth) acrylates of hydrogenated dicyclopentadiene or tricyclodecane dialkanol, di (meth) acrylates of dioxane glycol or dioxane dialkanol, di (meth) of alkylene oxide adducts of bisphenol A or bisphenol F Representative examples include acrylates, epoxy di (meth) acrylates of bisphenol A or bisphenol F, and the like.

  More specific examples of the bifunctional (meth) acrylate monomer include ethylene glycol di (meth) acrylate, 1,3-butanediol di (meth) acrylate, 1,4-butanediol di (meth) acrylate, 1 , 6-hexanediol di (meth) acrylate, 1,9-nonanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol di (meth) acrylate, ditri Methylolpropane di (meth) acrylate, diethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, dipropylene glycol di (meth) acrylate, tripropylene glycol di (meth) acrylate, polyethylene Glycol di (meth) acrylate, polypropylene glycol di (meth) acrylate, polytetramethylene glycol di (meth) acrylate, silicone di (meth) acrylate, di (meth) acrylate of hydroxypivalic acid neopentyl glycol ester, 2,2 -Bis [4- (meth) acryloyloxyethoxyethoxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxyethoxyethoxycyclohexyl] propane, hydrogenated dicyclopentadienyl di (meth) acrylate, tricyclo Decanedimethanol di (meth) acrylate, 1,3-dioxane-2,5-diyldi (meth) acrylate [also known as dioxane glycol di (meth) acrylate], hydroxypivalaldehyde and trimethylo Acetal compound with propane [chemical name: 2- (2-hydroxy-1,1-dimethylethyl) -5-ethyl-5-hydroxymethyl-1,3-dioxane], di (meth) acrylate, tris (hydroxyethyl) ) Isocyanurate di (meth) acrylate.

  The trifunctional or higher polyfunctional (meth) acrylate monomers include glycerin tri (meth) acrylate, trimethylolpropane tri (meth) acrylate, ditrimethylolpropane tri (meth) acrylate, ditrimethylolpropane tetra (meth) acrylate, pentaerythritol. Of tri- or higher functional aliphatic polyols such as tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. Poly (meth) acrylate is typical, and other poly (meth) acrylates of tri- or higher functional halogen-substituted polyols, with alkylene oxide of glycerin Tri (meth) acrylate, trimethylolpropane alkylene oxide adduct tri (meth) acrylate, 1,1,1-tris [(meth) acryloyloxyethoxyethoxy] propane, tris (hydroxyethyl) isocyanurate tri ( And (meth) acrylates.

  On the other hand, (meth) acrylate oligomers include urethane (meth) acrylate oligomers, polyester (meth) acrylate oligomers, and epoxy (meth) acrylate oligomers.

  The urethane (meth) acrylate oligomer is a compound having a urethane bond (—NHCOO—) and at least two (meth) acryloyloxy groups in the molecule. Specifically, a urethanization reaction product of a hydroxyl group-containing (meth) acrylate monomer and a polyisocyanate each having at least one (meth) acryloyloxy group and at least one hydroxyl group in the molecule, and a polyol Urethane reaction product of terminal isocyanate group-containing urethane compound obtained by reaction with isocyanate and (meth) acrylate monomer each having at least one (meth) acryloyloxy group and at least one hydroxyl group in the molecule, etc. It can be.

  Examples of the hydroxyl group-containing (meth) acrylate monomer used in the urethanization reaction include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 2-hydroxybutyl (meth) acrylate, and 2-hydroxy-3- Examples include phenoxypropyl (meth) acrylate, glycerin di (meth) acrylate, trimethylolpropane di (meth) acrylate, pentaerythritol tri (meth) acrylate, and dipentaerythritol penta (meth) acrylate.

  Examples of the polyisocyanate used for the urethanization reaction with the hydroxyl group-containing (meth) acrylate monomer include hexamethylene diisocyanate, lysine diisocyanate, isophorone diisocyanate, dicyclohexylmethane diisocyanate, tolylene diisocyanate, xylylene diisocyanate, and aromatic of these diisocyanates. Diisocyanates obtained by hydrogenating isocyanates (for example, hydrogenated tolylene diisocyanate, hydrogenated xylylene diisocyanate, etc.), di- or tri-isocyanates such as triphenylmethane triisocyanate, dibenzylbenzene triisocyanate, and Examples thereof include polyisocyanates obtained by multiplying the above diisocyanates.

  In addition, as polyols used to obtain terminal isocyanate group-containing urethane compounds by reaction with polyisocyanates, polyester polyols, polyether polyols, etc., as well as aromatic, aliphatic and alicyclic polyols should be used. Can do. Aliphatic and alicyclic polyols include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylol ethane, trimethylol propane, ditriol. Examples include methylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, and hydrogenated bisphenol A.

  The polyester polyol is obtained by a dehydration condensation reaction between the above polyols and a polybasic carboxylic acid or an anhydride thereof. Examples of polybasic carboxylic acids or anhydrides thereof can be represented by adding “(anhydrous)” to those that may be anhydrides, and are represented by (anhydrous) succinic acid, adipic acid, (anhydrous) maleic acid, (anhydrous) Itaconic acid, (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid, hexahydro (anhydrous) phthalic acid, etc.

  The polyether polyol may be a polyoxyalkylene-modified polyol obtained by a reaction of the above-described polyols or dihydroxybenzenes with an alkylene oxide, in addition to the polyalkylene glycol.

  The polyester (meth) acrylate oligomer is a compound having an ester bond and at least two (meth) acryloyloxy groups in the molecule. Specifically, it can be obtained by a dehydration condensation reaction using (meth) acrylic acid, polybasic carboxylic acid or anhydride thereof, and polyol. Examples of polybasic carboxylic acids or anhydrides thereof used in the dehydration condensation reaction can be represented by adding “(anhydrous)” to those that can be anhydrides. (Anhydrous) succinic acid, adipic acid, (anhydrous) There are maleic acid, (anhydrous) itaconic acid, (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, hexahydro (anhydrous) phthalic acid, (anhydrous) phthalic acid, isophthalic acid, terephthalic acid and the like. Examples of the polyol used for the dehydration condensation reaction include 1,4-butanediol, 1,6-hexanediol, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, neopentyl glycol, trimethylolethane, trimethylolpropane, Examples include ditrimethylolpropane, pentaerythritol, dipentaerythritol, dimethylolheptane, dimethylolpropionic acid, dimethylolbutanoic acid, glycerin, and hydrogenated bisphenol A.

  The epoxy (meth) acrylate oligomer can be obtained by addition reaction of polyglycidyl ether and (meth) acrylic acid, and has at least two (meth) acryloyloxy groups in the molecule. Examples of the polyglycidyl ether used for the addition reaction include ethylene glycol diglycidyl ether, propylene glycol diglycidyl ether, tripropylene glycol diglycidyl ether, 1,6-hexanediol diglycidyl ether, and bisphenol A diglycidyl ether.

  When a (meth) acrylic compound is added to the curable adhesive, the amount is preferably 20% by weight or less, more preferably 10% by weight or less, based on the amount of the entire active energy ray-curable compound. When the amount of the (meth) acrylic compound is increased, the adhesion between the polarizing film and the protective film tends to be lowered.

  When the curable adhesive contains a radical polymerizable compound such as the (meth) acrylic compound as described above, a photo radical polymerization initiator is preferably added. Any radical photopolymerization initiator may be used as long as it can initiate polymerization of a radical polymerizable compound such as a (meth) acrylic compound by irradiation with active energy rays, and a conventionally known one can be used. Specific examples of the photoradical polymerization initiator include acetophenone, 3-methylacetophenone, benzyldimethyl ketal, 1- (4-isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-methyl-1 -[4- (methylthio) phenyl-2-morpholinopropan-1-one, acetophenone-based initiators such as 2-hydroxy-2-methyl-1-phenylpropan-1-one; benzophenone, 4-chlorobenzophenone, 4, Benzophenone initiators such as 4'-diaminobenzophenone; benzoin ether initiators such as benzoin propyl ether and benzoin ethyl ether; thioxanthone initiators such as 4-isopropylthioxanthone; other xanthone, fluorenone, camphorquinone, benzaldehyde Anthraquinone, and the like.

  The compounding amount of the photo radical polymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 to 6 parts by weight with respect to 100 parts by weight of the radical polymerizable compound such as a (meth) acrylic compound. Part. When there is little quantity of radical photopolymerization initiator, hardening will become inadequate and it exists in the tendency for mechanical strength and the adhesiveness of a polarizing film and a protective film to fall. Moreover, when there is too much quantity of radical photopolymerization initiator, radical-polymerizability, such as an active energy ray hardening compound (a cation polymerizable curable compound containing an epoxy compound, and a (meth) acrylic compound) in a curable adhesive. The compound) is relatively reduced, and the durability performance of the resulting adhesive layer may be reduced.

  The curable adhesive can further contain a photosensitizer as necessary. By blending a photosensitizer, the reactivity of cationic polymerization and / or radical polymerization is improved, and the mechanical strength of the adhesive layer and the adhesion between the polarizing film and the protective film can be improved. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreductive dyes. More specific examples of photosensitizers include benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, and α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, o- Benzophenone derivatives such as methyl benzoylbenzoate, 4,4'-bis (dimethylamino) benzophenone, and 4,4'-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; Anthraquinone derivatives such as 2-chloroanthraquinone and 2-methylanthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; other α, α-diethoxyacetophenone, benzi And fluorenone, xanthone, uranyl compounds, halogen compounds, and the like. These photosensitizers may be used alone or in combination of two or more. The photosensitizer is preferably blended at a ratio of 0.1 to 20 parts by weight based on 100 parts by weight of the entire active energy ray-curable compound.

  The curable adhesive may be added with known polymer additives usually used for polymers. For example, primary antioxidants such as phenols and amines, sulfur secondary antioxidants, hindered amine light stabilizers (HALS), UV absorbers such as benzophenone, benzotriazole, or benzoate Is mentioned.

  Further, the curable adhesive may contain a solvent as necessary. The solvent is appropriately selected in consideration of the solubility of the components constituting the curable adhesive. Commonly used solvents include aliphatic hydrocarbons such as n-hexane and cyclohexane; aromatic hydrocarbons such as toluene and xylene; alcohols such as methanol, ethanol, propanol, isopropanol, and n-butanol. Ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; esters such as methyl acetate, ethyl acetate, and butyl acetate; cellosolves such as methyl cellosolve, ethyl cellosolve, and butyl cellosolve; methylene chloride and chloroform And halogenated hydrocarbons. The mixing ratio of the solvent is appropriately determined from the viewpoint of adjusting the viscosity depending on the processing purpose such as film formability. It is also effective to add a leveling agent in order to increase the smoothness when applied.

[Protective film laminated on another surface of polarizing film]
As described above, when the cycloolefin-based resin film 3 is bonded to one surface of the polarizing film 1, the protective film 6 made of another thermoplastic resin may be bonded to the other surface of the polarizing film. it can. The protective film 6 made of a thermoplastic resin is also bonded to the polarizing film 1 via an adhesive. The protective film 6 is conventionally widely used as a protective film forming material in the field, such as cellulose acetate resin, polyolefin resin, acrylic resin, polyimide resin, polycarbonate resin, and polyester resin. An appropriate material can be used. Among these, it is preferable to use a cellulose acetate-based resin film as a protective film from the viewpoint of mass productivity and adhesiveness. A cellulose acetate-based resin film is also preferably used as a protective film from the viewpoint of ease of providing the surface treatment layer and optical properties.

The cellulose acetate-based resin film is a film made of a cellulose portion or a complete acetate ester, and examples thereof include a triacetyl cellulose film and a diacetyl cellulose film. Examples of the cellulose acetate-based resin film include commercially available products such as “Fujitack TD80”, “Fujitack TD80UF” and “Fujitack TD80UZ” sold by Fuji Film Co., Ltd., Konica Minolta Opto Co., Ltd. sold and are "KC8UX2M", "KC8UY" and "KC4UEW" (trade names), etc. can be used.

  The adhesive used for the bonding of the polarizing film 1 and the protective film 6 is not particularly limited, and the same various adhesives previously listed as the adhesive used for the bonding of the polarizing film 1 and the cycloolefin-based resin film 3 are the same. It is preferable to use the same adhesive as that used for the cycloolefin resin film 3. In pasting these films using an adhesive, the surface treatment for improving the adhesiveness described above may be appropriately applied to the adhesive surface of the protective film 6 in order to improve the adhesiveness. When the protective film 6 is composed of a cellulose acetate-based resin film and is adhered to the polarizing film 1 using an aqueous adhesive, saponification treatment is performed as one of the preferable surface treatments applied to the cellulose acetate-based resin film. Can be mentioned. The saponification treatment is performed by immersing the film in an alkaline aqueous solution such as sodium hydroxide or potassium hydroxide.

  The protective film 6 is preferably thin, but if it is too thin, the strength tends to decrease and the workability tends to be poor. On the other hand, if it is too thick, the transparency tends to decrease or the weight of the polarizing plate tends to increase. . From such a viewpoint, the thickness of the protective film is usually 10 μm to 200 μm, preferably 20 μm to 150 μm, more preferably 30 μm to 100 μm, when the protective film is made of cellulose acetate resin.

  The protective film 6 may be subjected to a surface treatment such as an antiglare treatment, a hard coat treatment, an antistatic treatment, or an antireflection treatment on the surface opposite to the surface attached to the polarizing film 1.

[Production method of polarizing plate]
Next, the manufacturing method of the polarizing plate which concerns on this invention is demonstrated. As described above, in the present invention, the polarizing plate 1 is bonded to the cycloolefin resin film 3 via an adhesive to produce a polarizing plate. At that time, a primer layer 4 made of a cycloolefin resin is interposed between the cycloolefin resin film 3 and the adhesive layer 8. If desired, a cycloolefin-based resin film 3 is bonded to one side of the polarizing film 1, and a protective film 6 made of another thermoplastic resin is also bonded to the other side of the polarizing film 1 through an adhesive. be able to.

  Therefore, this polarizing plate can be produced through the following steps (i) to (iii). In the case where the cycloolefin-based resin film 3 is bonded to one surface of the polarizing film 1 and the protective film 6 made of another thermoplastic resin is bonded to the other surface of the polarizing film 1, the following (iv) ) Is adopted.

(I) a coating process for coating a primer coating liquid on the surface of the cycloolefin-based resin film 3;
(Ii) a drying step of drying the organic solvent contained in the primer coating solution to form the primer layer 4;
(Iii) The 1st bonding process of bonding the cycloolefin type resin film 3 in which the primer layer 4 was formed to the polarizing film 1 through an adhesive so that the primer layer 4 may become a bonding surface,
(Iv) The 2nd bonding process of bonding the protective film 6 which consists of a thermoplastic resin film to the surface on the opposite side to the surface where the cycloolefin type resin film 3 of the said polarizing film 1 was bonded. .

  In said coating process (i), the method of coating the above-mentioned primer coating liquid is used. As a coating method used for this purpose, a known method such as a casting method, a Meyer bar coating method, a gravure coating method, a comma coating method, a doctor blade method, a die coating method, a dip coating method, or a spraying method can be employed. The surface on which the primer layer is formed may be one side or both sides of the cycloolefin-based resin film 3, but the surface to be bonded to the polarizing film 1 is subjected to this treatment. Further, prior to the application of the primer coating solution, the surface of the cycloolefin-based resin film may be subjected to the surface treatment described above to improve wettability.

  The primer coating solution used in the coating step (i) may have a concentration and a viscosity so as to obtain a uniform primer layer 4 with an appropriate thickness. For example, it is appropriate that the concentration of the cycloolefin resin is about 1 to 20% by weight and the viscosity at 25 ° C. is 1,000 mPa · sec or less.

  Next, in said drying process (ii), the organic solvent contained in the primer coating liquid is dried. Natural drying may be used, but when drying is performed by heating, it is preferable to dry at a temperature not higher than the glass transition point of the cycloolefin-based resin film 3 from the viewpoint of preventing deformation of the film. This drying step (ii) can also be performed in parallel with the coating step (i), for example, drying while applying air to the surface on which the primer coating liquid has been applied in the coating step (i). .

  In the first bonding step (iii), the cycloolefin-based resin film 3 on which the primer layer 4 is formed is applied to the polarizing film 1 via an adhesive so that the primer layer 4 becomes a bonding surface. Paste. The bonding method here may be generally known, for example, casting method, Meyer bar coating method, gravure coating method, comma coater method, doctor blade method, die coating method, dip coating method, spraying method For example, a method of applying an adhesive on the adhesive surface of the polarizing film 1 and / or the primer layer 4 on the cycloolefin-based resin film 3 to be bonded to the polarizing film 1 and superimposing the two can be employed. Here, the casting method is a method of spreading and spreading the adhesive on the surface of the film to be coated while moving it in a substantially vertical direction, a substantially horizontal direction, or an oblique direction between the two. . After applying the adhesive, the polarizing film 1 and the cycloolefin-based resin film 3 are sandwiched and bonded together by a nip roll or the like. When adopting the method of applying the adhesive with a roll and then spreading it uniformly after dropping the adhesive between the films, the material of the roll used can be metal or rubber, etc. When passing between two rolls The rolls used for may be made of the same material or different materials.

  After the cycloolefin resin film 3 is bonded to the polarizing film 1 via an adhesive, it is dried when a water-based adhesive is used, or is irradiated with active energy rays when a curable adhesive is used. As a result, the adhesive is cured to form the adhesive layer 8. The drying process can be performed, for example, by blowing hot air. The temperature is usually in the range of 40 ° C to 100 ° C, preferably in the range of 60 ° C to 100 ° C. The drying time is usually 20 seconds to 1,200 seconds. On the other hand, the active energy rays applied to the curable adhesive can be ultraviolet rays, electron beams, X-rays, visible rays, etc., but in general, ultraviolet rays are preferably used. The active energy ray may be irradiated with the intensity and amount necessary for curing the adhesive.

  When bonding the protective film 6 which consists of another thermoplastic resin to the surface on the opposite side to the surface where the cycloolefin type resin film 3 is bonded of the polarizing film 1, said 2nd bonding process is further carried out. (Iv) is performed. In this step, the same method as in the first bonding step (iii) described above can be employed. It is preferable that a 2nd bonding process (iv) is performed simultaneously with said 1st bonding process (iii).

  The thickness of the adhesive layers 8 and 9 obtained after drying or curing is usually about 0.01 μm to 5 μm, but can be set to 1 μm or less when an aqueous adhesive is used. On the other hand, even when a curable adhesive is used, the thickness is preferably 2 μm or less. If the adhesive layers 8 and 9 are too thin, the adhesion may be insufficient. On the other hand, if the adhesive layer is too thick, the appearance of the polarizing plate may be poor.

[Other layers suitably provided on polarizing plate]
In the polarizing plate of this invention, an adhesive layer can be provided in the surface on the opposite side to the polarizing film 1 of the cycloolefin type-resin film 3 bonded by the polarizing film 1. FIG. This pressure-sensitive adhesive layer can be used for bonding the polarizing plate to a liquid crystal cell, bonding to another functional film such as a retardation film, and bonding to another layer. As the pressure-sensitive adhesive, an acrylic polymer, a silicone polymer, polyester, polyurethane, polyether or the like as a base polymer can be used. Among them, like acrylic adhesives, it has excellent optical transparency, retains appropriate wettability and cohesion, has excellent adhesion, and has weather resistance, heat resistance, etc. It is preferable to select and use a material that does not cause peeling problems such as floating and peeling under humidification conditions. In acrylic adhesives, alkyl esters of (meth) acrylic acid having an alkyl group having 20 or less carbon atoms such as methyl, ethyl and butyl groups, and (meth) acrylic acid and hydroxyethyl (meth) acrylate An acrylic copolymer having a weight average molecular weight of 100,000 or more, in which a glass transition temperature is preferably 25 ° C. or less, more preferably 0 ° C. or less, and a functional group-containing acrylic monomer comprising Useful as a base polymer.

  The pressure-sensitive adhesive layer is formed, for example, by dissolving or dispersing the pressure-sensitive adhesive composition including the above-described base polymer in an organic solvent such as toluene or ethyl acetate to prepare a 10% to 40% by weight solution, It can be carried out by a method of forming an adhesive layer by forming an adhesive layer on a protective film and transferring it onto a polarizing plate. In addition to the base polymer described above, a crosslinking agent is generally added to the adhesive. Furthermore, when bonding to a liquid crystal cell is intended, it is also preferable to mix a silane coupling agent. Although the thickness of an adhesive layer is determined according to the adhesive force etc., it is the range of 1 micrometer-50 micrometers normally.

  The pressure-sensitive adhesive may contain a filler made of glass fiber, glass beads, resin beads, inorganic powders such as metal powder, pigments, colorants, antioxidants, ultraviolet absorbers, and the like as necessary. . Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, and the like.

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

[Production Example 1] Production of polarizing film A polyvinyl alcohol film having an average polymerization degree of about 2,400 and a saponification degree of 99.9 mol% or more and a thickness of 75 µm was immersed in pure water at 30 ° C, and then iodine / iodination. It was immersed at 30 ° C. in an aqueous solution having a weight ratio of potassium / water of 0.02 / 2/100. Then, it was immersed at 56.5 ° C. in an aqueous solution having a potassium iodide / boric acid / water weight ratio of 12/5/100. Subsequently, after washing with pure water at 8 ° C., it was dried at 65 ° C. to obtain a polarizing film having a thickness of about 30 μm in which iodine was adsorbed and oriented on polyvinyl alcohol. Stretching was mainly performed in the iodine staining and boric acid treatment steps, and the total stretching ratio was 5.3 times.

[Production Example 2] Preparation of water-based adhesive acetoacetyl group-modified polyvinyl alcohol [trade name “Goseifamer Z-200”, manufactured by Nippon Synthetic Chemical Industry Co., Ltd., viscosity of 4% aqueous solution = 12.4 mPa · sec, Ken The degree of conversion = 99.1 mol%] was dissolved in pure water to prepare a 10% strength aqueous solution. This aqueous solution of acetoacetyl group-modified polyvinyl alcohol and sodium glyoxylate as a cross-linking agent are mixed so that the weight ratio of the former: latter solids is 1: 0.1, and acetoacetyl is added to 100 parts of water. A water-based adhesive was prepared by diluting with pure water so that the group-modified polyvinyl alcohol was 2.5 parts.

[Production Example 3] Preparation of UV curable adhesive The following components were mixed to prepare an UV curable adhesive. “UVACURE 1590” used as a photocationic polymerization initiator was obtained from Daicel Cytec Co., Ltd. in the form of a propylene carbonate solution.

(UV curable adhesive)
3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylate [“Celoxide 2021P” manufactured by Daicel Chemical Industries, Ltd.] 75 parts Bis (3-ethyl-3-oxetanylmethyl) ether [manufactured by Toagosei Co., Ltd. “Aron Oxetane OXT-221” 25 parts 4,4′-bis (diphenylsulfonio) diphenyl sulfide Bishexafluorophosphate-based photocationic polymerization initiator [“Daicel Cytec Co., Ltd.“ UVACURE
1590 "] 2.5 parts Silicone leveling agent [" SH710 "manufactured by Toray Dow Corning Co., Ltd.] 0.2 parts

[Production Example 4] Preparation of primer coating solution The same stretched cycloolefin-based resin film [trade name “ZEONOR FILM”, manufactured by Nippon Zeon Co., Ltd.] used in Example 1 described below is dissolved in cyclohexane. A 5% concentration primer coating solution was prepared.

[Example 1]
(A) Formation of primer layer on cycloolefin-based resin film Stretched cycloolefin-based resin film having an in-plane retardation value of 90 nm, a thickness direction retardation value of 79 nm, and a thickness of 22.7 μm [trade name “ZEONOR FILM” , Nippon Zeon Co., Ltd.] on one side, using a coating machine [Daiichi Rika Co., Ltd. bar coater], the primer coating solution prepared in Production Example 4 was applied and allowed to dry naturally. Then, the solvent (cyclohexane) contained in the primer coating solution was removed. Then, using a film thickness measuring instrument (“ZC-101” manufactured by Nikon Corporation), the film thickness of the cycloolefin-based resin film after forming the primer layer is measured, and the film thickness before forming the primer layer. The thickness of the primer layer was taken as the difference. These results are shown in Table 1. Moreover, when the retardation value of the film after the primer layer formation was measured using a retardation measuring device “KOBRA 21ADH” manufactured by Oji Scientific Instruments, both the in-plane retardation value and the thickness direction retardation value, There was almost no change compared to before the primer layer was formed. The primer layer of this cycloolefin-based resin film was subjected to corona treatment to obtain a protective film to be bonded to one surface of the polarizing film.

(B) Protective film to be bonded to the other surface A 40 μm-thick cellulose acetate resin film [trade name “KC4UEW”, manufactured by Konica Minolta Opto Co., Ltd.] is subjected to a corona treatment, so that the polarizing film It was set as the protective film bonded on one side.

(C) Production of Polarizing Plate The aqueous adhesive prepared in Production Example 2 was applied to both surfaces of the polarizing film produced in Production Example 1 in an atmosphere at 23 ° C., and the above-mentioned (A ), A stretched cycloolefin-based resin film that has been subjected to corona treatment by forming a primer layer, and a cellulose acetate-based resin film that has been corona-treated in (B) above is applied to the other adhesive-coated surface. Bonding was performed using a bonding apparatus [“LPA3301” manufactured by Fuji Plastics Co., Ltd.] so that the treated surface became a bonding surface with the polarizing film. This was dried at 80 ° C. for 5 minutes to produce a polarizing plate.

(D) Evaluation of adhesive strength After subjecting the cycloolefin resin film surface of the polarizing plate produced in (C) to corona treatment, an acrylic pressure-sensitive adhesive sheet was bonded to the corona-treated surface. The obtained pressure-sensitive adhesive-attached polarizing plate was cut into a test piece having a width of 25 mm and a length of about 200 mm. After the pressure-sensitive adhesive surface of the test piece was bonded to soda glass, it was subjected to pressure treatment in an autoclave at a pressure of 5 kgf / cm ² and a temperature of 50 ° C. for 20 minutes, and further in an atmosphere at a temperature of 23 ° C. and a relative humidity of 60%. And left for a day. In this state, using a universal tensile tester [“AG-1” manufactured by Shimadzu Corporation], hold the cellulose acetate resin film and the polarizing film at one end in the length direction (one side of 25 mm in width) of the test piece. , 90 ° peel test (JIS K 6854-1: 1999 “Adhesive-Peeling peel strength test method-No. 1) at an ambient temperature of 23 ° C. and a relative humidity of 60% at a crosshead speed of 200 mm / min. 1 part: 90 degree peeling ”), and the adhesive force between the cycloolefin-based resin film and the polarizing film was evaluated. The results are shown in Table 1.

[Example 2]
A primer layer was formed on one side of the stretched cycloolefin-based resin film in the same manner as in Example 1 (A) except that the count of the bar coater used when applying the primer coating solution was changed. The in-plane retardation value and the thickness direction retardation value of the film after forming the primer layer in this manner were almost unchanged compared with those before forming the primer layer. Furthermore, the surface of the primer layer was subjected to corona treatment to obtain a protective film to be bonded to one surface of the polarizing film. Thereafter, a polarizing plate was prepared and evaluated in the same manner as in Examples 1 (B) to (D). Table 1 summarizes the film thickness after forming the primer layer, the film thickness of the primer layer, and the adhesive force between the cycloolefin-based resin film and the polarizing film of the obtained polarizing plate.

[Comparative Example 1]
Example (B) to Example 1 except that a stretched cycloolefin-based resin film not forming a primer layer was used, and a corona treatment was applied to one surface thereof to form a protective film that was bonded to one surface of the polarizing film. A polarizing plate was prepared and evaluated in the same manner as (D). The film thickness of the used cycloolefin type resin film and the adhesive force between the cycloolefin resin film and the polarizing film of the obtained polarizing plate are summarized in Table 1.

[Example 3]
The primer layer of the stretched cycloolefin-based resin film on which the primer layer was formed in the same manner as in Example 2 was subjected to corona treatment to obtain a protective film that was bonded to one surface of the polarizing film. As the protective film to be bonded to the other surface of the polarizing film, a cellulose acetate-based resin film subjected to the same corona treatment as shown in Example 1 (B) was used.

  And the ultraviolet curable adhesive prepared in the manufacture example 3 was apply | coated to the primer layer to which the corona treatment of the extending | stretching cycloolefin type resin film was performed, and the corona treatment surface of a cellulose acetate type-resin film, respectively. Thereafter, the adhesive surface of the stretched cycloolefin-based resin film is provided on one surface of the polarizing film prepared in Production Example 1, and the adhesive surface of the cellulose acetate-based resin film is provided on the other surface of the polarizing film. Each was bonded, and the adhesive was cured by irradiating ultraviolet rays from the stretched cycloolefin-based resin film side to produce a polarizing plate. The obtained polarizing plate was evaluated in the same manner as in Example 1 (D), and the results are shown in Table 2.

[Comparative Example 2]
Polarized light in the same manner as in Example 3 except that a stretched cycloolefin-based resin film not formed with a primer layer was used, a corona treatment was performed on one surface thereof, and a protective film was bonded to one surface of the polarizing film. Plates were made and evaluated. The results are shown in Table 2.

  As can be seen from Tables 1 and 2, in Comparative Examples 1 and 2 using a cycloolefin resin film in which no primer layer is formed, the adhesive force between the polarizing film and the cycloolefin resin film is low. On the other hand, in Examples 1-3 which formed the primer layer which consists of cycloolefin type resin on the surface of a cycloolefin type resin film, and bonded polarizing film through the adhesive agent there, a polarizing film and a cycloolefin type The adhesive force between resin films has been remarkably increased.

1 …… Polarizing film,
3 …… Cycloolefin resin film,
4 …… Primer layer,
6 …… Protective film,
8, 9: Adhesive layer.

Claims (3)

A polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin, a cycloolefin-based resin film is bonded via an adhesive, and a polarizing plate is produced,
On the surface of the cycloolefin-based resin film, a solvent solution of the same kind of resin as the cycloolefin-based resin film is applied to form a primer layer, and then the surface on which the primer layer is formed is interposed through the adhesive. The polarizing plate is bonded to the polarizing film. The cycloolefin-based resin film on which the primer layer is formed is bonded to one surface of the polarizing film via the adhesive, and the other surface of the polarizing film is formed from a thermoplastic resin via an adhesive. the process according to claim 1 for laminating a protective film made. An adhesive for bonding the cycloolefin-based resin film on which the primer layer is formed to one surface of the polarizing film and a protective film made of the thermoplastic resin are bonded to the other surface of the polarizing film. For the same kind of adhesive,
Wherein the bonding of the cycloolefin-based resin film to one surface of the polarizing film, according to claim 2 in which the bonding of the protective film made of the thermoplastic resin to the other surface of the polarizing film are performed simultaneously Manufacturing method.

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