JP5720238B2 - Optical laminate and method for producing the same - Google Patents

Description

  The present invention relates to an optical laminate suitably used for a liquid crystal display device, and more specifically, a polarizing plate is typically provided on a glass plate having a liquid crystal cell substrate as a central member of the liquid crystal display device as a typical example through an adhesive layer. The present invention relates to an optical laminate formed by laminating plastic sheets as examples. The present invention also relates to a method for advantageously producing this optical laminate.

  The polarizing plate is useful as an optical component constituting a liquid crystal display device. Conventionally, a polarizing plate having a configuration in which a protective layer made of a transparent resin film is laminated on one side or both sides of a polarizing film made of polyvinyl alcohol resin via a water-based adhesive or the like. As such a transparent resin film, a triacetyl cellulose film is often used because of its excellent optical transparency and moisture permeability. Even when the protective layer is provided only on one side of the polarizing film, a resin film having an optical function such as a retardation function is provided on the other side of the polarizing film, which also serves as a protective function for the polarizing film. It is often laminated via. The polarizing plate configured as described above is bonded to a liquid crystal cell substrate with an adhesive (also called a pressure-sensitive adhesive) via another optical function layer as necessary, and becomes a liquid crystal panel to be used in a liquid crystal display device. Incorporated.

  The use of liquid crystal display devices is rapidly expanding as thin display screens such as liquid crystal televisions, liquid crystal monitors, and personal computers. In such expansion of applications, further reduction in thickness is also required for members constituting the same. As described above, a polarizing plate is generally bonded to a liquid crystal cell using an adhesive, but this can be easily peeled off from the liquid crystal cell and attached with another polarizing plate if there is any problem after bonding. Because it is convenient to match. However, the pressure-sensitive adhesive usually needs to have a thickness of at least about 20 μm in order to maintain an appropriate pressure-sensitive adhesive force, which is a bottleneck in reducing the thickness of a liquid crystal panel or a liquid crystal display device.

  There is also an attempt to reduce the thickness of the polarizing film by omitting the liquid crystal cell side protective layer, forming an adhesive layer directly on the polarizing film, and bonding the adhesive layer to the liquid crystal cell. However, in such a state where the polarizing film and the liquid crystal cell are directly bonded with the pressure-sensitive adhesive layer, when the heat resistance test exposed to high temperature is performed, the pressure-sensitive adhesive layer alone cannot sufficiently absorb the contraction of the polarizing film, Defects such as floating, peeling or foaming may occur between the polarizing film and the pressure-sensitive adhesive layer. In addition, when a thermal shock test (heat shock test) that repeats a high temperature state and a low temperature state was performed, the expansion and contraction of the polarizing film could not be sufficiently absorbed by the adhesive layer alone, and the polarizing film could break. .

  As another attempt to reduce the thickness of a polarizing plate, for example, Japanese Patent No. 4306269 (Patent Document 1) discloses an uncured epoxy on at least one surface of a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin. A technique for forming a protective film by applying a resin composition and then curing the composition is disclosed. However, in a state where the polarizing plate having the cured product of the epoxy resin composition as a protective film is bonded to the liquid crystal cell through the adhesive layer, the durability is not sufficient, for example, when a heat shock test is performed, After all, the polarizing film sometimes broke. In addition, in Japanese Patent No. 4306270 (Patent Document 2), an adhesive composed of a composition mainly composed of an epoxy resin not containing an aromatic ring is applied to a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin. The technique which bonds a protective film through an agent and makes it a polarizing plate is disclosed.

  On the other hand, Japanese Patent No. 3695484 (Patent Document 3) discloses a photosensitizer for a terpolymer of ethylene and an acrylate or methacrylate monomer and maleic acid or maleic anhydride on one surface of a polarizing film. And an adhesive layer composed of a photo-curable adhesive in which a predetermined amount of an unsaturated compound such as an acryloyloxy group-containing compound is blended to form a polarizing plate with an adhesive layer, and the liquid crystal cell substrate is formed through this adhesive layer. The technique which adhere | attaches a polarizing plate is disclosed, and providing the protective layer which consists of said photocurable adhesive agent in the other surface of a polarizing film is also described.

  However, when the polarizing plate is bonded to the liquid crystal cell substrate via the adhesive disclosed in this document, no large problem is seen in the small size liquid crystal cell in the heat resistance test or heat shock test, but the medium size to the large size In the case of the liquid crystal cell, there were problems that the polarizing plate was peeled off from the surface of the liquid crystal cell substrate and the polarizing film was cracked. Moreover, although the optical laminated body which bonded the polarizing plate to the liquid crystal cell substrate using this adhesive can be thinned, the polarizing plate once bonded to the liquid crystal cell cannot be easily peeled off. . Therefore, when any defect is found in the inspection after the bonding, the liquid crystal cell cannot be reused unless it is processed with a special organic solvent, resulting in poor economic merit.

  Japanese Patent No. 4093891 (Patent Document 4) discloses a technique in which a polarizing plate is supplied from a roll via an adhesive and directly bonded to a liquid crystal cell substrate.

Japanese Patent No. 4306269 (Japanese Patent Laid-Open No. 2004-245924) Japanese Patent No. 4306270 (Japanese Patent Laid-Open No. 2004-245925) Japanese Patent No. 3695484 (Japanese Patent Laid-Open No. 9-159828) Japanese Patent No. 4093891 (Japanese Patent Laid-Open No. 2004-4636)

  The object of the present invention is to achieve a thin, lightweight and durable performance by laminating a plastic sheet with a polarizing plate as a representative example and a glass plate with a liquid crystal cell substrate as a representative example via a specific adhesive. The object is to provide an excellent optical laminate. Another object of the present invention is to provide an advantageous method for producing such an optical laminate.

  According to the present invention, a glass plate and a plastic sheet are bonded via an adhesive layer, and the adhesive layer has at least one olefinic double bond and at least one olefinic double bond in the molecule. There is provided an optical layered body formed from an aqueous adhesive composition mainly composed of a polymer which is a compound having a carboxyl group.

  In this optical laminate, the adhesive composition forming the adhesive layer is a polymer in which the main monomer is a compound having at least one olefinic double bond and at least one carboxyl group in the molecule. In addition, it is preferable to contain a silane coupling agent. These adhesive compositions can further contain a crosslinking agent. The adhesive layer can have a thickness of 5 μm or less, and is suitable for thinning the optical laminate.

  In a typical form of these optical laminates, the glass plate is a liquid crystal cell substrate. In this case, a typical form of the plastic sheet is a polarizing plate having a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin. A polarizing plate can be equipped with said polarizing film and the transparent protective layer formed in the at least single side | surface. When bonding such a polarizing plate to a liquid crystal cell substrate, in one preferred embodiment, the polarizing plate is composed of a polarizing film and a transparent protective layer formed on one side thereof, and polarized light on the opposite side of the transparent protective layer. The film surface is directly bonded to the liquid crystal cell substrate via the adhesive layer. In another preferred embodiment, a polarizing plate is constituted by a polarizing film, a transparent protective layer formed on one surface of the polarizing film, and a retardation plate laminated on the other surface of the polarizing film, and the retardation plate side is , And bonded to the liquid crystal cell substrate through the adhesive layer.

  According to the present invention, there is also provided a method for producing an optical laminate in which a plastic sheet is bonded to a glass plate, wherein the main monomer is a molecule on at least one of the bonding surfaces of the glass plate and the plastic sheet. An adhesive layer forming step of providing an adhesive composition layer comprising an aqueous solution containing a polymer having at least one olefinic double bond and at least one carboxyl group therein, and the glass through the adhesive composition layer; A bonding process for bonding a plate and the plastic sheet, a bonding product obtained in the bonding process, an inspection process for removing a bonding product in which a defect is detected from the line, and a defect through the inspection process There is also provided a method for producing an optical laminate comprising a curing step of curing a layer of an adhesive composition present in a bonded product in which no is detected.

  Also in a typical form of this method, the glass plate is a liquid crystal cell substrate, and the plastic sheet is a polarizing plate having a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin. In this method, the bonded product in which the defect is detected in the inspection step can be configured to return the glass plate to the adhesive layer forming step after peeling off the plastic sheet.

  Since the optical laminate of the present invention can be directly bonded to a glass plate via an adhesive layer, the thickness can be reduced, and the adhesion between the glass plate and the plastic sheet is also good. Become. In particular, when the liquid crystal cell substrate is a glass plate and the polarizing plate is a plastic sheet, compared to a conventional optical laminate in which the polarizing plate is bonded to the liquid crystal cell substrate via an adhesive layer, Since the thickness can be reduced, the optical laminate, and thus the liquid crystal panel can be reduced in thickness and weight, and the adhesion between the polarizing plate and the liquid crystal cell substrate can be improved. Furthermore, by using an adhesive instead of a pressure-sensitive adhesive for bonding the liquid crystal cell substrate and the polarizing plate, it is possible to provide an optical laminate that can sufficiently withstand heat treatment during device assembly and environmental conditions during device use. .

  Moreover, according to the method of the present invention, the above optical laminate can be produced advantageously. In particular, if a defect such as a scratch on the surface, the presence of foreign matter, entrainment of bubbles, or misalignment is detected after the bonding process and before the curing process, the defect is detected. Since the bonded product is taken out of the production line, an optical laminate can be produced with a high yield. In addition, an adhesive composition composed of an aqueous solution is used for bonding between a glass plate with a liquid crystal cell substrate as a representative example and a plastic sheet with a polarizing plate as a representative example, and it is easy if it is before undergoing a curing step. The plastic sheet can be peeled off from the glass plate. Therefore, in the above inspection process, defects are detected, and the bonded product taken out of the production line is subjected to a simple process such as washing off the adhesive composition by washing with water after peeling the plastic sheet from there. Since it can return to the above-mentioned adhesive layer formation process, the production efficiency of an optical layered product can be raised further.

It is a cross-sectional schematic diagram which shows the basic layer structure of the optical laminated body which concerns on this invention. It is a cross-sectional schematic diagram which shows one form of the layer structure of the optical laminated body which concerns on this invention. It is a cross-sectional schematic diagram which shows another layer structure of the optical laminated body which concerns on this invention.

  In the present invention, as shown in a schematic cross-sectional view in FIG. 1, a glass plate 1 that is typically a liquid crystal cell substrate and a plastic sheet 3 that is typically a polarizing plate are interposed via an adhesive layer 2. The optical laminated body 10 is obtained by pasting. The adhesive layer 2 is formed from an aqueous adhesive composition whose main component is a polymer whose main monomer is a compound having at least one olefinic double bond and at least one carboxyl group in the molecule. In the present specification, hereinafter, a compound having at least one olefinic double bond and at least one carboxyl group in the molecule is sometimes referred to as an “unsaturated carboxylic acid compound”, and the unsaturated carboxylic acid compound is mainly referred to as “unsaturated carboxylic acid compound”. Such a polymer as a monomer may be referred to as a “carboxyl group-containing resin”. First, the adhesive composition and the adhesive layer 2 formed therefrom will be described, and then the description will proceed in the order of the glass plate 1 and the plastic sheet 3.

[Adhesive composition]
<Carboxyl group-containing resin>
In this invention, in order to adhere | attach the glass plate 1 and the plastic sheet 3, the aqueous adhesive composition which has carboxyl group-containing resin as a main component is used. As described above, the carboxyl group-containing resin is obtained from a compound having at least one olefinic double bond and at least one carboxyl group in the molecule (that is, an unsaturated carboxylic acid compound) as a main monomer. It is a polymer. The polymerization for obtaining the carboxyl group-containing resin can be performed by radical polymerization. The carboxyl group contained in the unsaturated carboxylic acid compound may be in the form of a salt such as an alkali metal salt or ammonium salt represented by lithium salt, sodium salt and potassium salt, or a plurality of carboxyl groups in the molecule. Any compound having a group may be in the form of an acid anhydride. Of course, when it is in the form of a carboxylate, it may be in a coexisting state with a free carboxyl group.

  Specific examples of the unsaturated carboxylic acid compound include (meth) acrylic acid and salts thereof, 2- (meth) acryloyloxyethyl succinate, 2- (meth) acryloyloxyethyl phthalate, 2- (meth) acryloyloxy. Carboxyl group-containing (meth) acrylic compounds such as ethyl hexahydrophthalate, β-carboxyethyl (meth) acrylate, and ω-carboxy-polycaprolactone modified (meth) acrylate, and salts thereof, fumaric acid, maleic acid, Examples thereof include unsaturated polycarboxylic acids such as itaconic acid, maleic anhydride, phthalic anhydride, trimetic anhydride, and itaconic anhydride, and acid anhydrides thereof. In the present specification, “(meth) acrylic acid” means both acrylic acid and methacrylic acid, and “(meth) acryloyloxy”, “(meth) acrylate”, etc. ) ”Has the same purpose.

  These unsaturated carboxylic acid compounds can be used as carboxyl group-containing resins constituting the adhesive composition in the form of their respective homopolymers, and in the form of copolymerizing a plurality of different compounds. You may use as carboxyl group-containing resin which comprises a composition.

  In the present invention, in some cases, it is possible to appropriately copolymerize an unsaturated carboxylic acid compound with another monomer copolymerizable therewith to obtain a carboxyl group-containing resin constituting the adhesive. As such other monomers, for example, (meth) acrylic monomers having no functional group, (meth) acrylic monomers having a polar functional group other than a carboxyl group, other than (meth) acrylic monomers And monomers having a sulfonic acid group, vinyl monomers other than (meth) acrylic monomers, monomers having a plurality of (meth) acryloyl groups in the molecule, and the like.

  Examples of (meth) acrylic monomers having no functional group include methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, n-butyl (meth) acrylate, ( Examples include 2-methoxyethyl acrylate and methoxypolyethylene glycol (meth) acrylate.

  Examples of polar functional groups other than carboxyl groups in (meth) acrylic monomers having polar functional groups other than carboxyl groups include hydroxyl groups, heterocyclic groups, amino groups different from heterocyclic rings, sulfonic acid groups, cyano groups, and amides. Examples include groups. Examples of the (meth) acrylic monomer having a hydroxyl group include 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, 4-hydroxybutyl (meth) acrylate, (meth) Examples include 2- or 3-chloro-2-hydroxypropyl acrylate, ethylene glycol mono (meth) acrylate, diethylene glycol mono (meth) acrylate, and polyethylene glycol mono (meth) acrylate. Examples of (meth) acrylic monomers having a heterocyclic group include acryloylmorpholine, tetrahydrofurfuryl (meth) acrylate, caprolactone-modified tetrahydrofurfuryl (meth) acrylate, 3,4-epoxycyclohexylmethyl (meth). Examples include acrylate and glycidyl (meth) acrylate. Examples of (meth) acrylic monomers having an amino group different from a heterocyclic ring include N, N-dimethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N -Dimethylaminopropyl (meth) acrylamide. Examples of (meth) acrylic monomers having a sulfonic acid group include 2- (meth) acryloylethanesulfonic acid, 2- (meth) acryloylpropanesulfonic acid, 2- (meth) acrylamido-2-methylpropane Examples include sulfonic acid. Examples of (meth) acrylic monomers having a cyano group include (meth) acrylonitrile. Examples of the (meth) acrylic monomer having an amide group include (meth) acrylamide and N-substituted (meth) acrylamide.

  Examples of monomers other than (meth) acrylic monomers having sulfonic acid groups include vinyl sulfonic acid and styrene sulfonic acid. In addition, including the (meth) acrylic monomer having the sulfonic acid group, the sulfonic acid group in the monomer is an alkali metal salt or ammonium salt typified by lithium salt, sodium salt and potassium salt. It may be in the form of salt.

  Examples of vinyl monomers other than (meth) acrylic monomers include fatty acid vinyl esters such as vinyl acetate, vinyl propionate, vinyl butyrate, vinyl 2-ethylhexanoate, and vinyl laurate; vinyl chloride and bromide Vinyl halides such as vinyl; vinylidene halides such as vinylidene chloride; nitrogen-containing aromatic vinyls such as 2-, 3- or 4-vinylpyridine, and N-vinylcarbazole; conjugated dienes such as butadiene, isoprene, and chloroprene. Mers; cyclic amides or ethers having a vinyl bond, such as N-vinyl-2-pyrrolidone and N-vinylcaprolactam.

  Examples of monomers having a plurality of (meth) acryloyl groups in the molecule are 1,4-butanediol di (meth) acrylate, 1,6-hexanediol di (meth) acrylate, 1,9 -Nonanediol di (meth) acrylate, ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, and tripropylene glycol di (meth) acrylate And a monomer having two (meth) acryloyl groups in the molecule; a monomer having three (meth) acryloyl groups in the molecule such as trimethylolpropane tri (meth) acrylate .

  The carboxyl group-containing resin contained in the adhesive composition preferably has an appropriate degree of polymerization. For example, when the aqueous solution has a concentration of 5% by weight, the viscosity is in the range of 3 to 300 mPa · sec. It is preferable that it is within a range of 5 to 100 mPa · sec.

  Of course, the adhesive composition used in the present invention may contain two or more of the carboxyl group-containing resins described above.

  The carboxyl group-containing resin constituting the adhesive layer 2 can be produced by various known methods such as a solution polymerization method, an emulsion polymerization method, a bulk polymerization method, and a suspension polymerization method. In the production of this carboxyl group-containing resin, a polymerization initiator is usually used. The polymerization initiator is used in an amount of about 0.001 to 5 parts by weight with respect to a total of 100 parts by weight of all monomers used for the production of the carboxyl group-containing resin.

  As the polymerization initiator, a thermal polymerization initiator or a photopolymerization initiator is used depending on how to give energy during the polymerization. Examples of the photopolymerization initiator include 4- (2-hydroxyethoxy) phenyl (2-hydroxy-2-propyl) ketone. Examples of thermal polymerization initiators include 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbohydrate). Nitrile), 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2'-azobis (2,4-dimethyl-4-methoxyvaleronitrile), dimethyl-2,2'-azobis (2- Methyl propionate), 2,2'-azobis (2-hydroxymethylpropionitrile), 2,2'-azobis (2-methylpropionamidine) hydrochloride, and 2,2'-azobis (1-imino- Azo compounds such as 1-pyrrolidino-2-methylpropane) hydrochloride; lauryl peroxide, tert-butyl hydroperoxide, benzoyl peroxide, tert-butyl peroxide Cibenzoate, cumene hydroperoxide, diisopropyl peroxydicarbonate, dipropyl peroxydicarbonate, tert-butyl peroxyneodecanoate, tert-butyl peroxypivalate, and (3,5,5-trimethylhexanoyl) ) Organic peroxides such as peroxides; inorganic peroxides such as potassium persulfate, ammonium persulfate, and hydrogen peroxide. A redox initiator using a peroxide and a reducing agent in combination can also serve as a polymerization initiator.

  Among the methods shown above, the solution polymerization method is preferably used for the production of the carboxyl group-containing resin. Specific examples of a suitable solution polymerization method include a desired monomer and water, optionally further mixed with an alcohol solvent, and a thermal polymerization initiator is added in a nitrogen atmosphere to give a temperature of about 40 to 100 ° C., preferably Is a method of stirring at about 60 to 90 ° C. for about 3 to 10 hours. In order to control the reaction, a monomer and / or a thermal polymerization initiator may be added continuously or intermittently during polymerization, or may be added in a state dissolved in water or an alcohol solvent. Here, methyl alcohol, ethyl alcohol, propyl alcohol, or the like can be used as the alcohol solvent.

  The concentration of the carboxyl group-containing resin in the adhesive composition is not particularly limited, but when used in the form of an aqueous solution, the carboxyl group-containing 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 preferably 1 to 15 parts by weight, more preferably 1 to 10 parts by weight, and particularly preferably 3 to 10 parts by weight. When the concentration of the carboxyl group-containing resin is less than 1 part by weight with respect to 100 parts by weight of water, the adhesiveness tends to decrease, and when the concentration is too large, There is a tendency that the optical characteristics are likely to deteriorate. The water used in this adhesive composition may be appropriate, such as pure water, ultrapure water, tap water, etc., but from the viewpoint of maintaining the uniformity and transparency of the formed adhesive layer 2, Pure water or ultrapure water is preferred. If necessary, an alcohol such as methanol or ethanol can be added to the aqueous adhesive solution.

<Other components constituting the adhesive composition>
In the present invention, the adhesive composition for forming the adhesive layer 2 preferably contains a silane coupling agent in order to improve the adhesion between the adhesive layer 2 and the glass plate 1.

  The silane coupling agent has a hydrolyzable group such as an alkoxy group bonded to a silicon atom, and a reactive functional group such as a vinyl group, amino group, epoxy group, haloalkyl group, (meth) acryloyl group or mercapto group. It may be a compound to which an organic group having Specific examples of the silane coupling agent having a vinyl group include vinyltrimethoxysilane, vinyltriethoxysilane, and vinyltris (2-methoxyethoxy) silane. Specific examples of the silane coupling agent having an amino group include N- (2-aminoethyl) -3-aminopropylmethyldimethoxysilane, N- (2-aminoethyl) -3-aminopropyltrimethoxysilane, 3- Aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane and the like are included. Specific examples of the silane coupling agent having an epoxy group include 3-glycidoxypropyltrimethoxysilane, 3-glycidoxypropyltriethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropyl. Examples include dimethoxymethylsilane, 3-glycidoxypropylethoxydimethylsilane, 2- (3,4-epoxycyclohexyl) ethyltrimethoxysilane, and the like. Specific examples of the silane coupling agent having a haloalkyl group include 3-chloropropylmethyldimethoxysilane, 3-chloropropyltrimethoxysilane and the like. Specific examples of the silane coupling agent having a (meth) acryloyl group include 3- (meth) acryloyloxypropyltrimethoxysilane and the like. Specific examples of the silane coupling agent having a mercapto group include 3-mercaptopropyltrimethoxysilane. Two or more silane coupling agents may be used in combination. Among these, considering the solubility in water and the usable time (pot life) as an adhesive, a silane coupling agent having an epoxy group is preferable. For example, 3-glycidoxypropyltrimethoxysilane is One of the preferred silane coupling agents.

  The silane coupling agent may be of a silicone oligomer type. When the silicone oligomer is shown in the form of (monomer)-(monomer) copolymer, for example, the following can be mentioned.

  3-mercaptopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-mercaptopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-mercaptopropyltriethoxysilane-tetramethoxysilane copolymer, and 3-mercaptopropyltriethoxysilane-tetraethoxy A copolymer containing a mercaptopropyl group, such as a silane copolymer;

  Mercaptomethyl groups such as mercaptomethyltrimethoxysilane-tetramethoxysilane copolymer, mercaptomethyltrimethoxysilane-tetraethoxysilane copolymer, mercaptomethyltriethoxysilane-tetramethoxysilane copolymer, and mercaptomethyltriethoxysilane-tetraethoxysilane copolymer. Containing copolymers;

  3-methacryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropyltriethoxysilane -Tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-methacryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-methacryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-methacryloxyyl propylmethyldiethoxysilane-tetra Toki bell Ranco polymers such as, methacryloyloxypropyl group containing copolymers;

  3-acryloyloxypropyltrimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltrimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropyltriethoxysilane -Tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-acryloyloxypropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-acryloyloxypropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-acryloyloxypropylmethyldiethoxysilane-tetraethoxysilane Rimmer such as, acryloyloxypropyl group-containing copolymer;

  Vinyltrimethoxysilane-tetramethoxysilane copolymer, vinyltrimethoxysilane-tetraethoxysilane copolymer, vinyltriethoxysilane-tetramethoxysilane copolymer, vinyltriethoxysilane-tetraethoxysilane copolymer, vinylmethyldimethoxysilane-tetramethoxysilane copolymer, Vinyl group-containing copolymers such as vinylmethyldimethoxysilane-tetraethoxysilane copolymer, vinylmethyldiethoxysilane-tetramethoxysilane copolymer, and vinylmethyldiethoxysilane-tetraethoxysilane copolymer;

  3-aminopropyltrimethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltrimethoxysilane-tetraethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetramethoxysilane copolymer, 3-aminopropyltriethoxysilane-tetraethoxysilane Copolymer, 3-aminopropylmethyldimethoxysilane-tetramethoxysilane copolymer, 3-aminopropylmethyldimethoxysilane-tetraethoxysilane copolymer, 3-aminopropylmethyldiethoxysilane-tetramethoxysilane copolymer, and 3-aminopropylmethyldiethoxy Amino group-containing copolymers such as silane-tetraethoxysilane copolymers.

  Since these silane coupling agents are often liquids, they can be directly mixed in an aqueous solution containing a carboxyl group-containing resin. The amount of the silane coupling agent in the adhesive composition is usually in the range of about 0.01 to 200 parts by weight with respect to 100 parts by weight of the carboxyl group-containing resin. The blending amount of the silane coupling agent with respect to 100 parts by weight of the carboxyl group-containing resin is preferably 150 parts by weight or less, more preferably 100 parts by weight or less, especially 50 parts by weight or less, and preferably 0.03 parts by weight or more. . Adhesion between the adhesive layer 2 and the glass plate 1 is improved by blending 0.01 parts by weight or more, particularly 0.03 parts by weight or more of the silane coupling agent with respect to 100 parts by weight of the carboxyl group-containing resin. The effect is expressed. Depending on the type of carboxyl group-containing resin and silane coupling agent, for example, the effect of maintaining high adhesion even when a thermal shock test is conducted is the combination of silane coupling agent with 100 parts by weight of carboxyl group-containing resin. If the amount is about 30 parts by weight or about 50 parts by weight, it may be further increased. However, since the possibility that the silane coupling agent bleeds out from the adhesive layer 2 when the blending amount of the silane coupling agent becomes too large, it is preferable to set the blending amount so as not to bleed out.

  In the present invention, the adhesive composition for forming the adhesive layer 2 can further contain a crosslinking agent. A crosslinking agent can also be mix | blended with the aqueous solution of carboxyl group-containing resin which does not contain a silane coupling agent, and can also be mix | blended with the aqueous solution of carboxyl group-containing resin with a silane coupling agent. In general, it is preferable to contain a crosslinking agent in addition to the silane coupling agent.

The cross-linking agent can be a compound having at least two functional groups in the molecule that are reactive with a carboxyl group-containing resin. The functional group constituting the crosslinking agent includes an isocyanato group (—NCO), an epoxy group (crosslinked —O—), a hydroxyl group (—OH), a hydrazide group (—CONHNH ₂ ), an oxazoline group (cyclic —C ₃ H ₄ NO) and the like are included. In addition, salts of divalent, trivalent or tetravalent metals such as magnesium, calcium, iron, nickel, zinc, aluminum, titanium and zirconium can be used as a crosslinking agent.

  Specific examples of the crosslinking agent (isocyanate compound) having an isocyanato group include tolylene diisocyanate, hydrogenated tolylene diisocyanate, adducts of trimethylolpropane and tolylene diisocyanate, diphenylmethane diisocyanate, triphenylmethane triisocyanate, isophorone diisocyanate, these Ketoxime block or phenol block. Specific examples of the crosslinking agent (epoxy compound) having an epoxy group include ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, di- or tri-glycidyl ether of glycerin, 1,6-hexanediol diglycidyl ether, trimethylol. Examples include propane triglycidyl ether, diglycidyl aniline, diglycidyl amine, and a 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 the crosslinking agent having a hydroxyl group include methylol melamine.

  The cross-linking agent is preferably dissolved in water together with the carboxyl group-containing resin to form an adhesive composition. 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 carboxyl group-containing resin, and is usually about 0.1 to 60 parts by weight, preferably 1 with respect to 100 parts by weight of the carboxyl group-containing resin. ~ 50 parts by weight. By blending the cross-linking agent within this range, good adhesiveness can be obtained. If the amount of the crosslinking agent is too large, the reaction of the crosslinking agent proceeds in a short time, and the adhesive composition tends to gel early. As a result, the usable time as an adhesive (pot life) Becomes extremely short, making industrial use difficult.

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

[Adhesive layer]
In the present invention, at least one of the bonding surfaces of the glass plate 1 and the plastic sheet 3 is an adhesive composition described above, preferably an adhesive composition comprising an aqueous solution in which the above components are blended. A layer is provided, the glass plate 1 and the plastic sheet 3 are bonded through the layer of the adhesive composition, and the layer of the adhesive composition is cured to form the adhesive layer 2. The thickness of the adhesive layer 2 can be 5 μm or less, and is usually about 0.001 to 5 μm, preferably 0.01 to 2 μm, more preferably 0.05 to 2 μm or 0.05 to 1 μm. is there. When the thickness of the adhesive layer exceeds 5 μm, there is a possibility that the appearance of the plastic sheet 3 is poor.

[Glass plate]
As the glass plate 1 on which the plastic sheet 3 is bonded via the adhesive layer 2, any material generally called glass can be used. As described above, the present invention is particularly useful when the glass plate 1 is a liquid crystal cell substrate constituting a liquid crystal display device. The liquid crystal cell substrate constitutes a liquid crystal cell by sandwiching liquid crystal with another substrate, and this liquid crystal cell becomes a core member of the liquid crystal display device. The glass plate 1 can be composed of various commonly known materials such as soda lime glass, low alkali borosilicate glass, and non-alkali aluminoborosilicate glass, but non-alkali glass is particularly preferably used for the liquid crystal cell. It is done.

[Plastic sheet]
The plastic sheet 3 bonded to the glass plate 1 through the adhesive layer 2 is also limited as long as the resin that exhibits adhesive ability by the aqueous solution of the carboxyl group-containing resin becomes the bonding surface to the glass plate 1. It can be used without. Examples of the resin that exhibits adhesive ability by an aqueous solution of a carboxyl group-containing resin include cellulose acetate resins, polyvinyl alcohol resins, and cycloolefin resins including triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate. Examples thereof include resin, chain olefin resin such as polypropylene resin, polyethylene terephthalate resin, and acrylic resin.

  Among these, the plastic sheet in which the cellulose acetate-based resin or the polyvinyl alcohol-based resin becomes the bonding surface to the glass plate 1 is attached to the glass plate 1 through an adhesive made of an aqueous solution containing a carboxyl group-containing resin. High adhesion is expressed. If necessary, the surface to be bonded to the glass plate 1 of the plastic sheet 3 is subjected to an easy adhesion treatment such as a saponification treatment or a corona discharge treatment as a representative example, then formation of an adhesive layer, and further to the glass plate 1 It can also be used for pasting. For example, when the cellulose acetate-based resin serves as a bonding surface to the glass plate 1, the adhesive strength of the aqueous solution of the carboxyl group-containing resin can be further increased by performing saponification treatment on the surface. Further, even when a chain olefin resin such as a cycloolefin resin or a polypropylene resin is a bonding surface to the glass plate 1, an easy adhesion treatment such as a corona discharge treatment is performed on the surface. As a result, a high adhesive force due to the aqueous solution of the carboxyl group-containing resin is developed.

  The thickness of the plastic sheet 3 is not particularly limited as long as the plastic sheet 3 can be bonded to the glass plate 1, but is preferable because it is preferably used for bonding to the glass plate 1 while being wound in a roll shape. In consideration of flexibility, it is generally preferably 500 μm or less, more preferably 300 μm or less, and particularly preferably 200 μm or less.

<Polarizer>
As described above, the optical laminate of the present invention is a polarizing plate having a polarizing film in which the glass plate 1 in FIG. 1 is a liquid crystal cell substrate, and the plastic sheet 3 is a polyvinyl alcohol resin adsorbed and oriented with a dichroic dye. It is particularly useful in some cases. Although the above polarizing film itself can be used alone as the plastic sheet 3, since the polarizing film alone is fragile, at least one side thereof, particularly on the side opposite to the side to be bonded to the liquid crystal cell substrate 1, is provided. Those provided with a transparent protective layer are preferably used.

  FIG. 2 is a schematic cross-sectional view showing one embodiment of the layer configuration of the optical laminate according to the present invention. In this embodiment, a transparent protective layer 7 is provided on one surface of the polarizing film 6 to form a polarizing plate 5, and the surface of the polarizing film 6 opposite to the surface on which the transparent protective layer 7 is provided is directly attached to the adhesive layer 2. The optical laminate 11 is configured by being bonded to the liquid crystal cell substrate 1. That is, in the optical laminated body 11 of FIG. 2, the polarizing film 6 is laminated | stacked with respect to the glass plate 1 in contact with the adhesive bond layer 2, and transparent protection is carried out on the surface on the opposite side to the adhesive bond layer 2 in the polarizing film 6. Layer 7 is laminated.

  FIG. 3 is a schematic cross-sectional view showing another layer configuration of the optical laminate according to the present invention. In this embodiment, the transparent protective layer 7 is provided on one side of the polarizing film 6, and an appropriate resin layer 8 is provided on the other side of the polarizing film 6 to form the polarizing plate 5, and the resin layer 8 side is provided with the adhesive layer 2. The optical laminate 12 is configured by being bonded to the liquid crystal cell substrate 1.

  As described above, the polarizing plate 5 may have any layer as long as it includes the polarizing film 6, but the layers other than the polarizing film 6 are two layers or less, particularly one layer or two layers. It is preferable from the viewpoint of thinning the optical laminate or the liquid crystal panel while protecting the polarizing film 6. From such a viewpoint, as shown in FIG. 2, the polarizing film 6 has a transparent protective layer 7 on one surface, and the surface of the polyvinyl alcohol-based resin film (polarizing film surface) opposite to the transparent protective layer 7. The form of being directly bonded to the liquid crystal cell substrate 1 via the adhesive layer 2 is a preferable one. When the form shown in FIG. 2 is adopted, although depending on the type of the transparent protective layer 7, the thickness of the polarizing plate 5 can be set to 100 μm or less, for example.

<Polarized film>
The polarizing film 6 constituting the polarizing plate 5 is obtained by adsorbing and orienting a dichroic dye on a polyvinyl alcohol resin. More specifically, a film obtained by adsorbing and orienting a dichroic dye on a uniaxially stretched polyvinyl alcohol resin film is preferably used.

  The polyvinyl alcohol resin constituting the polarizing film 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. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, and vinyl ethers. The saponification degree of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 to 100 mol%. The polyvinyl alcohol resin constituting the polarizing film may be further modified. For example, polyvinyl formal or polyvinyl acetal modified with aldehydes can be used as the polyvinyl alcohol resin. The degree of polymerization of the polyvinyl alcohol resin constituting the polarizing film is usually about 1,000 to 10,000, preferably 1,500 to 10,000.

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

  A polarizing film is usually a process of uniaxially stretching a raw film made of a polyvinyl alcohol resin as described above, a process of dyeing a polyvinyl alcohol resin film with a dichroic dye and adsorbing the dichroic dye, two colors It is manufactured through a step of treating a polyvinyl alcohol-based resin film adsorbed with a functional dye with an aqueous boric acid solution and a step of washing with water after the treatment with an aqueous boric acid solution.

  Uniaxial stretching may be performed before dyeing with a dichroic dye, may be performed simultaneously with dyeing, or may be performed after dyeing. When uniaxial stretching is performed after dyeing with a dichroic dye, the uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, it is also possible to perform uniaxial stretching in these several steps. In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, it may be dry stretching such as stretching in the air, or may be wet stretching in which stretching is performed in a state swollen with a solvent. The draw ratio is usually about 3 to 8 times.

  For example, the dyeing of the polyvinyl alcohol resin film with the dichroic dye is performed by immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye. As the dichroic dye, iodine, a dichroic organic dye, or the like is used. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

  When iodine is used as the dichroic dye, it is usually dyed by a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide. The iodine content in this aqueous solution is usually about 0.01 to 0.5 parts by weight with respect to 100 parts by weight of water, and the potassium iodide content is usually 0.5 with respect to 100 parts by weight of water. About 10 parts by weight. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C., and the immersion time (dyeing time) in this aqueous solution is usually about 30 to 300 seconds.

On the other hand, when a dichroic organic dye is used as the dichroic dye, it is usually dyed by a method of immersing a polyvinyl alcohol resin film in an aqueous dye solution containing a water-soluble dichroic organic dye. The content of the dichroic organic dye in this dye aqueous solution is usually about 1 × 10 ⁻³ to 1 × 10 ⁻² parts by weight with respect to 100 parts by weight of water. The aqueous dye solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. The temperature of the aqueous dye solution is usually about 20 to 80 ° C., and the immersion time (dyeing time) in the aqueous dye solution is usually about 30 to 300 seconds.

  The boric acid treatment after dyeing with the dichroic dye is performed by immersing the dyed polyvinyl alcohol-based resin film in a boric acid-containing aqueous solution. The boric acid content in the boric acid-containing aqueous solution is usually about 2 to 15 parts by weight, preferably 5 to 12 parts by weight with respect to 100 parts by weight of water. When iodine is used as the dichroic dye, the boric acid-containing aqueous solution preferably further contains potassium iodide. In this case, the content of potassium iodide in the boric acid-containing aqueous solution is usually about 2 to 20 parts by weight, preferably 5 to 15 parts by weight with respect to 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually about 100 to 1,200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C or higher, preferably 50 to 85 ° C.

  The polyvinyl alcohol resin film after the boric acid treatment is usually washed with water. The water washing treatment is performed, for example, by immersing a boric acid-treated polyvinyl alcohol resin film in water. The temperature of water in the water washing treatment is usually about 5 to 40 ° C., and the immersion time is about 2 to 120 seconds. After washing with water, a drying process is performed to obtain a polarizing film. The drying process can be performed using a hot air dryer or a far infrared heater. A drying temperature is about 40-100 degreeC normally. The time for the drying treatment is usually about 120 to 600 seconds.

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

<Transparent protective layer>
The transparent protective layer 7 provided on at least one surface of the polarizing film 6 includes, for example, a chain olefin resin including a cellulose acetate resin, a cycloolefin resin, a polypropylene resin, and a polymethyl methacrylate resin. It is composed of an appropriate thermoplastic resin film that has been widely used as a protective layer forming material in the art, such as acrylic resins, polyimide resins, polycarbonate resins, and polyester resins including polyethylene terephthalate resins. be able to. Moreover, the transparent protective layer 7 can also be comprised with the hardened | cured material of an active energy ray curable resin composition. From the viewpoint of mass productivity and adhesiveness, among these, a cellulose acetate resin, a cycloolefin resin, a chain olefin resin, a film made of an acrylic resin or a polyester resin, or an active energy ray curable resin composition It is preferable to use a cured product of the product as the transparent protective layer 7.

  When the transparent protective layer 7 is composed of a thermoplastic resin film, the thickness is usually about 10 to 80 μm, but it is preferable to make it relatively thin about 10 to 50 μm. On the other hand, when the transparent protective layer 7 is composed of a cured product of the active energy ray-curable resin composition, the thickness can be 10 μm or less, for example, about 1 to 10 μm.

  The cellulose acetate-based resin film used as the transparent protective layer 7 is a film made of a cellulose part or a complete acetate ester, and examples thereof include a triacetyl cellulose film and a diacetyl cellulose film. Examples of such cellulose acetate-based resin films include commercially available products such as “Fujitac TD80”, “Fujitac TD80UF” and “Fujitac TD80UZ” sold by Fuji Film Co., Ltd., Konica Minolta Opto Co., Ltd. Commercially available “KC8UX2M” and “KC8UY” (both are trade names) can be used.

  The cycloolefin resin used for the transparent protective layer 7 is a heat having a monomer unit composed of a cyclic olefin (cycloolefin) such as norbornene, tetracyclododecene (also known as dimethanooctahydronaphthalene), or a derivative thereof. It is a plastic resin (also called a thermoplastic cycloolefin resin). This cycloolefin-based resin can be a hydrogenated product of the above-mentioned cycloolefin ring-opening polymer or a hydrogenated product of a ring-opening copolymer using two or more kinds of cycloolefins, It may be an addition copolymer with an aromatic compound having a olefin and / or a vinyl group. A polar group may be introduced into the cycloolefin resin.

  When the transparent protective layer 7 is formed using an addition copolymer of a cycloolefin and a chain olefin and / or an aromatic compound having a vinyl group, examples of the chain olefin include ethylene, propylene, and vinyl. Examples of the aromatic compound having a group include styrene, α-methylstyrene, and nuclear alkyl-substituted styrene. In such a copolymer, the unit of the monomer composed of cycloolefin may be 50 mol% or less (preferably 15 to 50 mol%). In particular, when the transparent protective layer 7 is formed using a terpolymer of a cycloolefin, a chain olefin and an aromatic compound having a vinyl group, the monomer unit composed of cycloolefin is relatively The amount can be small. In such a terpolymer, the monomer unit composed of a chain olefin and the monomer unit composed of an aromatic compound having a vinyl group are each usually about 5 to 80 mol%.

  The cycloolefin resin is an appropriate commercial product, for example, “TOPAS” manufactured by TOPAS ADVANCED POLYMERS GmbH and available from Polyplastics Co., Ltd. in Japan, “ARTON” (ARTON) sold by JSR Co., Ltd. ), “ZEONOR” and “ZEONEX” sold by Nippon Zeon Co., Ltd., “APEL” sold by Mitsui Chemicals, Inc. (both trade names), etc. Can be used. When forming 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. In addition, for example, “Zeonor Film” sold by Nippon Zeon Co., Ltd., “Arton Film” sold by JSR Co., Ltd., etc. are used to form a transparent film of cycloolefin-based resin that has been formed in advance. It can also be used as the protective layer 7.

  The chain olefin resin used for the transparent protective layer 7 is preferably a polypropylene resin having propylene as a main constituent unit. The polypropylene resin can be a homopolymer of propylene, and other copolymerizable monomers, typically ethylene, are copolymerized with propylene up to about 10% by weight, for example, about 1 to 10% by weight. It may be a thing. A polypropylene resin can also be formed into a film used for the transparent protective layer 7 by forming a film by a known method such as a solvent casting method or a melt extrusion method.

  The acrylic resin used for the transparent protective layer 7 is preferably a polymethyl methacrylate resin having methyl methacrylate as a main structural unit. Acrylic rubber particles may be blended with the polymethyl methacrylate resin. Moreover, it may be set as the multilayered structure which has the layer of the polymethyl methacrylate type resin with which the light diffusing agent was mix | blended, and the layer of the polymethyl methacrylate type resin without the light diffusing agent being mixed. A polymethyl methacrylate resin is usually formed into a film by a melt extrusion method. In the case of a multilayer structure, a coextrusion method can be employed.

  The polyester resin used for the transparent protective layer 7 is preferably a polyethylene terephthalate resin mainly composed of terephthalic acid and ethylene glycol. Polyethylene terephthalate resin can also be formed into a film by a known method such as a solvent casting method or a melt extrusion method. This film is further uniaxially or biaxially stretched to give strength and transparency. Those having a higher value are preferably used as the transparent protective layer 7.

  On the other hand, the active energy ray-curable resin composition used for the transparent protective layer 7 can contain, for example, an epoxy-based active energy ray-curable compound, and it is also effective to add an oxetane compound. . Thus, when it contains an epoxy compound and optionally further contains an oxetane compound, a photocationic polymerization initiator is usually also blended.

  The active energy ray-curable resin composition used for the transparent protective layer 7 may contain a radical polymerizable compound, specifically a (meth) acrylic compound, in addition to the epoxy compound and the optional oxetane compound. It is valid. By using a (meth) acrylic compound in combination, a transparent protective layer having high hardness, excellent mechanical strength, and superior durability can be obtained. Furthermore, adjustment of the viscosity and curing rate of the active energy ray-curable resin composition can be performed more easily. In the active energy ray-curable resin composition for forming the transparent protective layer 7, the (meth) acrylic compound can be added up to about 70% by weight based on the total amount of the active energy ray-curable compound. The blending amount of the (meth) acrylic compound is more preferably 35 to 70% by weight, especially 40 to 60% by weight. When the compounding amount of the (meth) acrylic compound exceeds 70% by weight, the adhesion with the polarizing film tends to be lowered. When blending such a (meth) acrylic compound, a radical photopolymerization initiator is also blended.

  The transparent protective layer 7 of the polarizing plate 5 may have a surface treatment layer on the surface opposite to the surface to be attached to the polarizing film 6, and examples of such surface treatment include an antiglare treatment and a hard coat. Treatment, antistatic treatment, antireflection treatment and the like are included. Moreover, the coating layer which consists of a liquid crystalline compound, its high molecular weight compound, etc. may be formed in the surface on the opposite side to the surface stuck to the polarizing film 6 of the transparent protective layer 7. FIG.

  When the transparent protective layer 7 is a resin film, an adhesive is used for adhering the polarizing film 6 and the transparent protective layer 7. Examples of the adhesive for this purpose include a curable resin composition containing an active energy ray-curable compound and an aqueous adhesive in which an adhesive component is dissolved or dispersed in water.

  From the viewpoint of eliminating the drying step and increasing productivity, it is preferable to use a curable resin composition containing an active energy ray-curable compound as an adhesive. In this case, it is preferable to use an epoxy cationic polymerizable compound as the active energy ray-curable compound. It is also effective to add an oxetane compound which is also cationically polymerizable in addition to the epoxy compound. Thus, when it contains an epoxy compound and optionally further contains an oxetane compound, a photocationic polymerization initiator is usually also blended. When the curable resin composition is used as an adhesive, usually, the polarizing film 6 and the transparent protective layer 7 are bonded via the curable resin composition layer, and then the active energy ray is irradiated to the bonded material. Then, the curable resin composition layer is cured.

  On the other hand, from the viewpoint of thinning the adhesive layer and thinning the entire polarizing plate 5, a water-based adhesive in which the adhesive component is dissolved or dispersed in water is preferable. Examples of such a water-based adhesive include an adhesive composition mainly composed of a polyvinyl alcohol-based resin or a urethane resin. When a polyvinyl alcohol resin is used as the main component of the water-based adhesive, the polyvinyl alcohol resin may be partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol, anion-modified polyvinyl alcohol resin, or acetoacetyl group-modified. Modified polyvinyl alcohol resins such as polyvinyl alcohol resins modified with methylol groups, polyvinyl alcohol resins modified with methylol groups, and polyvinyl alcohol resins modified with a cation may also be used. When using a polyvinyl alcohol resin as an adhesive component, the adhesive is usually prepared as an aqueous solution of a polyvinyl alcohol resin. The density | concentration of the polyvinyl alcohol-type resin in an adhesive agent is about 1-10 weight part normally with respect to 100 weight part of water, Preferably it is 1-5 weight part. It is also effective to use a crosslinking agent in combination.

<Resin layer disposed on the liquid crystal cell substrate side of the polarizing plate>
When the resin layer 8 is provided on the liquid crystal cell substrate 1 side of the polarizing film 6 as in the example shown in FIG. 3, the resin layer 8 is the same as the transparent protective layer 7 provided on the opposite side of the polarizing film 6, or In addition to being a transparent protective layer different from that, it may be an optical functional layer. As an example of the optical functional layer, there is a retardation plate used for the purpose of compensation of retardation by a liquid crystal cell or compensation of viewing angle. Examples of retardation plates include birefringent films made of stretched films of various resins, films in which discotic liquid crystals and nematic liquid crystals are oriented and fixed, and retardation development of the above liquid crystals and inorganic layered compounds on a film substrate. For example, a coating film containing a substance is formed and the orientation is fixed. In this case, a cellulose acetate-based resin film such as triacetyl cellulose is preferably used as a film substrate that supports a coating film containing a retardation-expressing substance.

  When a birefringent film made of a stretched resin film is used as a phase difference plate, cellulose acetate-based resin, cycloolefin-based resin, polypropylene-based resin, etc. are used from the viewpoint of retardation development and retardation value stability. It is suitable as a resin material constituting the retardation plate. These resins themselves are the same as those described above as the resin film constituting the transparent protective layer 7. By uniaxially stretching or biaxially stretching these resin films, a phase difference can be imparted and a phase difference plate can be obtained. In this case, the draw ratio is usually 1.1 to 5 times, preferably 1.1 to 3 times.

  Cellulose acetate-based resin films and cycloolefin-based resin films are also commercially available with a phase difference. For example, cellulose acetate resin films with phase difference include “KC4FR-T” and “KC4HR-T” sold by Konica Minolta Opto Co., Ltd. Cycloolefin with phase difference. Examples of resin films include “Essina” and “SCA40” sold by Sekisui Chemical Co., Ltd. In addition, “Zeonor Film” sold by Nippon Zeon Co., Ltd. and “Arton Film” sold by JSR Co., Ltd., which are listed as examples of cycloolefin resin films that can be the transparent protective layer 7 previously. There are also grades with a phase difference.

  When the resin layer 8 is composed of a resin film including a phase difference plate, the polarizing film 6 and the resin layer are used using the same adhesive as described for the pasting of the polarizing film 6 and the transparent protective layer 7. 8 can be bonded.

  When it is intended to provide the polarizing plate 5 with a phase difference compensation function or a viewing angle compensation function using a liquid crystal cell, the transparent protective layer 7 is formed on one surface of the polarizing film 6 as shown in FIG. A phase difference plate is laminated as the resin layer 8 on the other surface of the polarizing film 6 to form a polarizing plate 5, and the phase difference plate side is disposed on the liquid crystal cell substrate via the adhesive layer 2 described above. The form bonded to 1 is effective. Thus, even when the retardation film is laminated on the surface of the polarizing film 6 on the liquid crystal cell substrate 1 side, the entire thickness of the polarizing plate 5 can be 200 μm or less. In addition, if the transparent protective layer 7 and the resin layer 8 serving as a retardation plate are appropriately selected, the thickness of the entire polarizing plate 5 can be set to 100 μm or less.

[Method for producing optical laminate]
Next, the manufacturing method of the optical laminated body which concerns on this invention is demonstrated. The optical laminated body demonstrated above can be advantageously manufactured by the method provided with each process shown below. Hereinafter, description will be made with reference to the reference numerals shown in FIG.

(A) Adhesive layer forming step of providing an adhesive composition layer comprising an aqueous solution containing a carboxyl group-containing resin on at least one of the bonding surfaces of the glass plate 1 and the plastic sheet 3;
(B) a bonding step of bonding the glass plate 1 and the plastic sheet 3 through the layer of the adhesive composition;
(C) An inspection process in which the bonded product obtained in the bonding process is inspected and the bonded product in which the defect is detected is taken out of the production line; and (d) No defect is detected through the inspection process. A curing step of curing the layer of the adhesive composition present in the bonded product.

  This manufacturing method is particularly useful when the glass plate 1 is a liquid crystal cell substrate and the plastic sheet 3 is a polarizing plate having the polarizing film described above. The polarizing plate may be a polarizing film alone or may be laminated with other layers in advance as described above. However, as described above with reference to FIGS. It is preferable that the transparent protective layer 7 formed on at least one surface of the film 6 is provided. Thus, when the polarizing plate 5 on which at least the polarizing film 6 and the transparent protective layer 7 are laminated is used as the plastic sheet 1, the plastic sheet 1 is formed in a state in which the layers constituting the polarizing plate 5 are laminated. It uses for said adhesive bond layer formation process (a). Hereinafter, each process shown above is demonstrated in order.

<Adhesive layer forming step (a)>
In the adhesive layer forming step (a), at least one of the bonding surfaces of the glass plate 1 and the plastic sheet 3 is provided with an adhesive composition layer made of an aqueous solution containing a carboxyl group-containing resin. In forming the adhesive layer, for example, a method of applying the adhesive composition to the bonding surface of the glass plate 1 and / or the bonding surface of the plastic sheet 3 can be employed. Moreover, although it is one form of application | coating, it supplies so that the plastic sheet 3 may be bonded together to the end of the surface of the glass plate 1, and it sprays said adhesive composition between both, and the glass plate 1 and a plastic sheet It is also possible to adopt a method in which a layer of the adhesive composition is formed on each of the bonding surfaces of 3 and the next bonding step is continuously performed while pressing with a roll from the outside of the plastic sheet 3.

  The means for applying the adhesive composition to the bonding surface of the glass plate 1 and / or the bonding surface of the plastic sheet 3 is not particularly limited. For example, a doctor blade, a wire bar, a slit coater, a die coater, a comma Various coating methods such as coater and gravure coater can be used. Moreover, since each coating method has an optimum viscosity range, the viscosity of the adhesive composition (aqueous solution) can be adjusted by adjusting the concentration of the carboxyl group-containing resin in the adhesive composition. .

<Bonding step (b)>
In the next bonding step (b), the glass plate 1 and the plastic sheet 3 are bonded together via the layer of the adhesive composition formed in the upper adhesive layer forming step (a). In this step, as described above, the plastic sheet 3 is supplied to one end of the surface of the glass plate 1 through a layer of the adhesive composition, and is applied while being pressed from the outside of the plastic sheet 3 with a roll. The method of combining is advantageously employed. Thus, the method of bonding to the other end of the surface of the glass plate 1 while pressing with a roll from one end of the surface of the glass plate 1 is advantageous from the viewpoint of suppressing entrainment of bubbles.

<Inspection process (c)>
In the inspection step (c), the bonded product obtained in the upper bonding step (b) is inspected, and the bonded product in which the defect is detected is taken out of the production line. Of course, if no defect is detected, the bonded product is directly sent to the next curing step (d). In this inspection step (c), the presence / absence of scratches on the surface, the presence / absence of foreign matter, the presence / absence of bubbles, the presence / absence of axial deviation, etc. are inspected. Such an inspection can be performed by a method usually employed in the manufacturing stage of the liquid crystal panel.

  The bonded product in which the defect is detected in the inspection step (c) is taken out of the production line. At this stage, since the layer of the adhesive composition made of an aqueous solution containing a carboxyl group-containing resin has not yet been cured, the plastic sheet 3 can be easily peeled from the glass plate 1. Therefore, since the glass plate 1 after peeling off the plastic sheet 3 can easily remove the adhesive composition on the surface thereof by washing or the like, it can be returned to the adhesive layer forming step (a) after washing. The operation of taking the bonded product in which the defect is detected in the inspection step (c) to the outside of the production line, peeling the plastic sheet 3 therefrom and returning the glass plate 1 to the adhesive layer forming step (a) is performed as a pressure-sensitive adhesive layer. This corresponds to a rework operation in which, after the polarizing plate with the mark is attached to the liquid crystal cell substrate, if there is any problem, the polarizing plate is peeled off and reattached. In the present invention, the adhesive is used in spite of bonding the plastic sheet 3 (typically a polarizing plate) to the glass plate 1 (typically a liquid crystal cell substrate) using an adhesive instead of an adhesive. Since it is aqueous solution, there exists an advantage that such rework operation can be performed easily.

<Curing step (d)>
The bonded product that was not detected in the inspection step (c) and passed was a layer of the adhesive composition existing between the glass plate 1 and the plastic sheet 3 in the next curing step (d). Harden. In the curing step (d), the layer of the adhesive composition is cured by high-temperature drying, irradiation with active energy rays, or the like to obtain the adhesive layer 2. When employing high-temperature drying, the temperature is preferably in the range of about 40 to 80 ° C. In the case of curing by irradiation with active energy rays, the active energy rays to be used can be ultraviolet rays, X-rays, electron energy rays and the like. There is also a method in which the layer of the adhesive composition is cured at room temperature.

[Liquid Crystal Display]
In the optical laminates 10 to 12 of the present invention, another liquid crystal cell substrate is disposed on the opposite side of the surface of the liquid crystal cell substrate 1 to which the polarizing plate 5 is bonded, and the liquid crystal is sandwiched between the two. By doing so, it can be set as a liquid crystal cell or a liquid crystal panel. A liquid crystal display device is configured using the liquid crystal cell or the liquid crystal panel as a display element. The liquid crystal cell itself in a state in which the liquid crystal is sealed between the two liquid crystal cell substrates is the liquid crystal cell substrate 1 in FIGS. 1 to 3, and a polarizing plate is bonded to one or both surfaces according to the present invention. Is generally. Since the optical layered body of the present invention is excellent in durability against thermal shock tests and the like, the liquid crystal display device produced as described above is also excellent in durability against thermal shock tests and the like. Thus, a reduction in thickness and weight is achieved.

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

[Production Example 1]
380 parts of water and 100 parts of acrylic acid are added to a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer, and the internal temperature is set to 80 ° C. while substituting the air in the apparatus with nitrogen gas to prevent oxygen. I raised it. Thereafter, a total amount of a solution prepared by dissolving 0.2 part of potassium persulfate (polymerization initiator) in 20 parts of water was added. Further, the inner temperature was maintained at 79 to 81 ° C. for 6 hours, and finally water was added to adjust the polyacrylic acid concentration to 5%. The viscosity of the obtained 5% aqueous polyacrylic acid solution was 52 mPa · sec.

[Production Example 2]
To a reaction vessel equipped with a cooling pipe, a nitrogen introduction pipe, a thermometer and a stirrer, 870 parts of water and 100 parts of acrylic acid are added, and the air inside the apparatus is replaced with nitrogen gas to keep the internal temperature 80 ° C. I raised it. Thereafter, a total amount of a solution in which 0.3 part of potassium persulfate (polymerization initiator) was dissolved in 30 parts of water was added. Further, the inner temperature was maintained at 79 to 81 ° C. for 6 hours, and finally water was added to adjust the polyacrylic acid concentration to 5%. The viscosity of the obtained 5% polyacrylic acid aqueous solution was 41 mPa · sec.

[Production Example 3]
Add 415 parts of water, 100 parts of acrylic acid and 9.5 parts of itaconic acid to a reaction vessel equipped with a cooling pipe, nitrogen introduction pipe, thermometer and stirrer, and replace the air inside the apparatus with nitrogen gas to contain no oxygen. The internal temperature was raised to 80 ° C. Thereafter, a total amount of a solution prepared by dissolving 0.2 part of potassium persulfate (polymerization initiator) in 23 parts of water was added. Further, the inner temperature was maintained at 79 to 81 ° C. for 6 hours, and finally water was added to adjust the concentration of acrylic acid / itaconic acid copolymer to 5%. The viscosity of a 5% aqueous solution of the resulting acrylic acid / itaconic acid copolymer was 27 mPa · sec.

[Production Example 4]
Add 400 parts of water, 100 parts of acrylic acid and 6.2 parts of methyl acrylate to a reaction vessel equipped with a cooling pipe, nitrogen introduction pipe, thermometer and stirrer, and replace the air inside the apparatus with nitrogen gas to prevent oxygen The internal temperature was raised to 80 ° C. while containing. Thereafter, a total amount of a solution prepared by dissolving 0.2 part of potassium persulfate (polymerization initiator) in 23 parts of water was added. Further, the inner temperature was maintained at 79 to 81 ° C. for 6 hours, and finally water was added to adjust the concentration of acrylic acid / methyl acrylate copolymer to 5%. The viscosity of a 5% aqueous solution of the resulting acrylic acid / methyl acrylate copolymer was 29 mPa · sec.

[Example 1]
(A) Preparation of aqueous adhesive composition To the 5% polyacrylic acid aqueous solution obtained in Production Example 1, 3-glycidoxypropyltrimethoxysilane as a silane coupling agent and polyacrylic acid: silane coupling agent The mixture was mixed so that the solid content weight ratio was 1: 0.2, and further diluted with pure water so that polyacrylic acid was 5 parts with respect to 100 parts of water to prepare an adhesive composition.

(B) Production of optical laminated body A transparent glass substrate (a liquid crystal cell substrate) was prepared, and the glass substrate was washed using an ultrasonic glass washer [manufactured by Micro Engineering Co., Ltd.]. In addition, a polarizing plate in which a protective film made of triacetyl cellulose having a thickness of 40 μm is bonded to one side of a polarizing film in which iodine is adsorbed and oriented on a polyvinyl alcohol film via a polyvinyl alcohol adhesive [Sumitomo Chemical Co., Ltd. Product name “SR0661A-XNSY”, thickness of about 70 μm] was prepared. This polarizing plate is cut into a square size of 10 cm × 10 cm, and the adhesive prepared in (a) above is applied to the polarizing film surface on which the protective film is not bonded and one surface of the glass substrate after the cleaning. The composition was applied within 30 minutes after preparation, and the adhesive surfaces were bonded together. This was left at room temperature for 24 hours and then dried at 60 ° C. for 3 minutes to produce an optical laminate. The thickness of the adhesive layer after drying is about 0.1 μm.

[Example 2]
The adhesive composition was prepared in the same manner as in Example 1 (a) except that the weight ratio of the polyacrylic acid: silane coupling agent was changed to 1: 0.3. And the optical laminated body was produced by the method similar to (b) of Example 1 except using this adhesive composition.

[Example 3]
The adhesive composition was prepared in the same manner as in Example 1 (a) except that the polyacrylic acid: silane coupling agent weight ratio was changed to 1: 0.4. And the optical laminated body was produced by the method similar to (b) of Example 1 except using this adhesive composition.

[Example 4]
Example 1 except that the 5% polyacrylic acid aqueous solution obtained in Production Example 2 was mixed so that the weight ratio of the solid content of the polyacrylic acid: silane coupling agent was 1: 0.1. An adhesive composition was prepared in the same manner as in (a). And the optical laminated body was produced by the method similar to (b) of Example 1 except using this adhesive composition.

[Example 5]
Using a 5% aqueous solution of acrylic acid / itaconic acid copolymer obtained in Production Example 3 and mixing so that the weight ratio of the solid content of the copolymer: silane coupling agent is 1: 0.2. Except for this, an adhesive composition was prepared in the same manner as in Example 1 (a). And the optical laminated body was produced by the method similar to (b) of Example 1 except using this adhesive composition.

[Example 6]
An adhesive composition was prepared in the same manner as in the first half of Example 5 except that the solid content weight ratio of the copolymer: silane coupling agent was changed to 1: 0.3. And the optical laminated body was produced by the method similar to (b) of Example 1 except using this adhesive composition.

[Example 7]
Using a 5% aqueous solution of the acrylic acid / methyl acrylate copolymer obtained in Production Example 4, the mixture was mixed so that the solid weight ratio of the copolymer: silane coupling agent was 1: 0.3. Except for this, an adhesive composition was prepared in the same manner as in Example 1 (a). And the optical laminated body was produced by the method similar to (b) of Example 1 except using this adhesive composition.

[Comparative Example 1]
3-glycidoxypropyltrimethoxysilane as a silane coupling agent in a 20% aqueous solution of polyvinylpyrrolidone [trade name “K-85W” manufactured by Nippon Shokubai Co., Ltd.], and a solid content of polyvinylpyrrolidone: silane coupling agent The mixture was mixed so that the weight ratio was 1: 0.1, and further diluted with pure water so that polyvinylpyrrolidone was 2 parts with respect to 100 parts of water to prepare an adhesive composition. Using this adhesive composition, an optical laminate was produced in the same manner as in (b) of Example 1.

[Comparative Example 2]
In place of the adhesive composition comprising the polyacrylic acid aqueous solution, an acrylic pressure-sensitive adhesive having a thickness of 25 μm was used, and this acrylic pressure-sensitive adhesive was used on one surface of the transparent glass substrate in Example 1. The polarizing film surface where the protective film of the same polarizing plate was not bonded was bonded. Thereafter, it was treated in a 50 ° C. autoclave at a pressure of 5 kg / cm ² (about 0.5 MPa) for 20 minutes to produce an optical laminate.

[Comparative Example 3]
An optical laminate was produced in the same manner as in Example 1 (b) except that pure water was used instead of the adhesive composition composed of the polyacrylic acid aqueous solution.

[Evaluation test]
(A) Durability test The durability of the optical laminates produced in the above examples and comparative examples was evaluated by the following method.

  When a heat resistance test is performed for 100 hours of storage at a temperature of 80 ° C. for drying for 100 hours, when a heat resistance test is performed for 100 hours at a temperature of 60 ° C. and a relative humidity of 90%, and after heating to 70 ° C., −35 For each of the cases where a heat shock resistance test (represented as “HS resistance resistance test” in the table) was repeated, where the process of lowering the temperature to 0 ° C. and then increasing the temperature to 70 ° C. was taken as 1 cycle (2 hours). The optical layered body after the test was visually observed. The results were classified according to the following criteria and summarized in Table 1.

(Evaluation criteria for heat, moisture and heat shock tests)
A: No change in appearance such as floating, peeling or cracking of polarizing film is observed.
○: Almost no change in appearance such as floating, peeling or cracking of polarizing film.
(Triangle | delta): Appearance changes, such as a float, peeling, and a crack of a polarizing film, are somewhat conspicuous.
X: Appearance changes such as floating, peeling, and cracks in the polarizing film are noticeable.

(B) Reworkability evaluation 3 hours after the polarizing plate was bonded to the glass substrate (in Examples 1 to 7 and Comparative Examples 1 and 3, the third hour during standing for 24 hours at room temperature, and in Comparative Example 2 an autoclave) In order to see if the polarizing plate can be peeled off from the glass substrate 3 hours after the completion of the treatment), the polarizing plate is peeled off from the adhesion test piece at a speed of 300 mm / min. A peel test was performed. The results were classified according to the following criteria and summarized in Table 1.

(Evaluation criteria for reworkability)
○: It was peeled off.
X: The polarizing plate was broken and could not be peeled off.

  The optical laminated bodies of Examples 1 to 7 are thin and excellent in both durability and reworkability. On the other hand, in the optical laminate of Comparative Example 1 using an aqueous polyvinylpyrrolidone solution as the adhesive composition, problems occurred in the durability test. Moreover, in the optical laminated body of the comparative example 2 which used the acrylic adhesive for adhesion | attachment with glass and a polarizing plate, the malfunction generate | occur | produced in heat shock resistance and rework property. Furthermore, in the optical laminated body of the comparative example 3 which used the pure water for the adhesive agent, the malfunction generate | occur | produced in heat resistance and heat shock resistance.

1 …… Glass plate (liquid crystal cell substrate),
2 ... Adhesive layer,
3 …… Plastic sheet
5 ... Polarizing plate,
6 …… Polarizing film,
7: Transparent protective layer,
8 …… Resin layer,
10, 11, 12... Optical laminate.

Claims (12)

Glass plate and plastic sheet are stuck by an adhesive layer, the adhesive layer is a compound having at least one carboxyl group and at least one olefinic double bond principal monomer in the molecule heavy An optical layered body formed from a water-based adhesive composition mainly composed of a coalescence.   The optical laminate according to claim 1, wherein the aqueous adhesive composition further contains a silane coupling agent.   The optical laminate according to claim 1 or 2, wherein the aqueous adhesive composition further contains a crosslinking agent.   The optical layered body according to claim 1, wherein the adhesive layer has a thickness of 5 μm or less.   The optical laminated body according to claim 1, wherein the glass plate is a liquid crystal cell substrate.   The optical laminate according to claim 5, wherein the plastic sheet is a polarizing plate having a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin.   The said polarizing plate is an optical laminated body of Claim 6 provided with the said polarizing film and the transparent protective layer formed in the at least single side | surface.   The polarizing plate includes the polarizing film and a transparent protective layer formed on one side thereof, and the polarizing film surface opposite to the transparent protective layer is directly on the liquid crystal cell substrate via the adhesive layer. The optical laminated body of Claim 7 currently bonded.   The polarizing plate includes the polarizing film, a transparent protective layer formed on one surface of the polarizing film, and a retardation plate laminated on the other surface of the polarizing film, the retardation plate side being the adhesive layer. The optical laminated body of Claim 7 currently bonded by the said liquid crystal cell substrate via. A method for producing an optical laminate in which a plastic sheet is bonded to a glass plate,
Adhesive composition comprising an aqueous solution containing a polymer having a main monomer having at least one olefinic double bond and at least one carboxyl group in the molecule on at least one of the bonding surfaces of the glass plate and the plastic sheet. An adhesive layer forming step of providing a layer of,
A bonding step of bonding the glass plate and the plastic sheet through a layer of the adhesive composition;
The bonding product obtained in the bonding process is inspected, and the bonding product in which defects are detected is inspected to the outside of the production line, and the bonding product in which no defects are detected through the inspection process is present. The manufacturing method of the optical laminated body characterized by providing the hardening process which hardens the layer of adhesive composition.   The method according to claim 10, wherein the glass plate is a liquid crystal cell substrate, and the plastic sheet is a polarizing plate having a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin.   The method according to claim 10 or 11, wherein the bonded product in which a defect is detected in the inspection step is configured to return the glass plate to the adhesive layer forming step after peeling the plastic sheet.

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