TWI512074B - Photo-cured adhesive composition, polarizing plate and producing method for the same, optical member and liquid crystal display device - Google Patents

Description

Photocurable adhesive composition, polarizing plate, manufacturing method thereof, optical member, and liquid crystal display device

The present invention relates to a photocurable adhesive composition used for bonding a polarizer and a protective film in a polarizing plate, a polarizing plate using the adhesive composition to adhere a protective film to a polarizing member, and the manufacture of the polarizing plate method. Further, the present invention relates to an optical member and a liquid crystal display device using the polarizing plate.

The polarizing plate is used as one of optical parts constituting a liquid crystal display device. Usually, the polarizing plate is used by being assembled in a liquid crystal display device in a state in which the protective film is applied to the two layers of the polarizing member. Although it is also known that a protective film is provided only on one side of the polarizing member, in most cases, a protective film is used as a protective film on the other surface not only as a protective film but also as a layer of other optical functions. Further, as a method for producing a polarizing material, a method of drying a uniaxially stretched polyvinyl alcohol resin film dyed with a dichroic dye by boric acid treatment, washing with water, and drying is widely known.

Usually, the polarizer is directly adhered to the protective film after the above washing and drying. This is because the physical strength of the polarizer after drying is weak, and if it is temporarily taken up, problems such as cracking occur in the machine direction. Therefore, in general, after drying the polarizer, the protective film is adhered to both surfaces of the polarizer after the direct application of the water-based adhesive. As a protective film, a triethylenesulfonated cellulose film having a thickness of 30 to 120 μm is used.

The polarizer and the protective film are followed by a protective film made of a triethylenesulfonated cellulose film. Although many of the polyvinyl alcohol-based adhesives are used, there are also attempts to use an urethane system. An adhesive is substituted for the adhesive. Japanese Patent Publication No. 7-120617 (Patent Document 1) discloses a polarizing member having a high water content and a cellulose acetate-based protective film (for example, triethylenesulfonyl group) using an amine ester prepolymer as an adhesive. The cellulose film) is followed.

On the other hand, due to the high moisture permeability of the triethylenesulfonyl cellulose, the resin film is adhered to the polarizing plate on both sides as a protective film, under conditions of damp heat, for example, at a temperature of 70 ° C and a relative humidity of 90%. Underneath, there will be problems such as deterioration. Here, there has also been proposed a method of solving this problem by using a resin film having a lower moisture permeability than a triethylenesulfonated cellulose film as a protective film. For example, an amorphous polyolefin resin is known as a protective film. . In the above-mentioned Japanese Patent Publication No. Hei 6-51117 (Patent Document 2), it is disclosed that a thermoplastic resin-borne norbornene-based resin sheet is used as a protective film on at least one surface of a polarizing member and laminated.

When a protective film having a low moisture permeability is adhered by a conventional device, an adhesive agent using water as a main solvent, such as an aqueous solution of polyvinyl alcohol, is used, and after the polyvinyl alcohol-based polarizing member is adhered to the protective film, the solvent is further applied. In the so-called Wet Lamination method of drying , there is a problem that sufficient adhesive strength or poor appearance is not obtained. This is due to the low moisture permeability of the film over the third acetylsalicylic generally more hydrophobic cellulose film, or because of low moisture permeability, so that it can not be sufficiently dried grounds of the water as a solvent.

Japanese Laid-Open Patent Publication No. 2000-321432 (Patent Document 3) proposes a polyvinyl alcohol-based polarizer and a protective film made of a thermoplastic saturated norbornene-based resin, which is made of polyurethane. It is followed by an adhesive. However, the polyurethane adhesive has a problem that it takes a long time to harden, and the subsequent force is not necessarily sufficient.

On the other hand, it is also known that a different type of protective film is adhered to both surfaces of a polarizing member, and it is disclosed in Japanese Laid-Open Patent Publication No. 2002-174729 (Patent Document 4). A protective film made of an amorphous polyolefin resin is adhered to one surface of the polarizing member, and a resin different from the amorphous polyolefin resin is adhered to the other surface, for example, a protective film made of triacetyl cellulose. In Japanese Laid-Open Patent Publication No. 2005-208456 (Patent Document 5), it is proposed to laminate a ring on one surface of a polarizing film made of a polyvinyl alcohol-based resin via a water-based first adhesive containing a specific amine ester resin. On the other surface, the olefin-based resin film is laminated with a water-based second adhesive different from the first adhesive, for example, an aqueous solution of a polyvinyl alcohol-based resin.

In the case of the above-mentioned Patent Document 4, which is referred to as an amorphous polyolefin-based resin, or in the above-mentioned Patent Document 5, it is referred to as a cycloolefin-based resin, and means, for example, norbornene or a derivative thereof, or dimethyl bridge octahydronaphthalene ( Dimethanooctahydronaphthalene) A thermoplastic resin which has a monomer unit derived from a polycyclic cyclic olefin and which is preferably hydrogenated when a double bond remains as in the case of a ring-opening polymer.

In JP-A-2004-245925 (Patent Document 6), an epoxy resin containing no aromatic ring as a main component is disclosed, and it is proposed to irradiate the active energy source to the adhesive and then carry out cationic polymerization. A method of causing a polarizer to follow a protective film. The epoxy-based adhesive disclosed herein is particularly effective for adhering various transparent resin films including amorphous polyolefin-based resins and cellulose-based resins to polarizers, but it is known that acrylic resins are used in particular. When it is a protective film, its adhesive force is not necessarily enough.

[Previous Technical Literature]

Patent Document 1: Japanese Patent Laid-Open No. Hei 7-120617

Patent Document 2: Japanese Patent Laid-Open No. Hei 6-51117

Patent Document 3: Japanese Laid-Open Patent Publication No. 2000-321432

Patent Document 4: Japanese Laid-Open Patent Publication No. 2002-174729

Patent Document 5: Japanese Laid-Open Patent Publication No. 2005-208456

Patent Document 6: Japanese Laid-Open Patent Publication No. 2004-245625

In order to solve the problem of the polyvinyl alcohol-based polarizer and the low-humidity protective film being adhered by the wet-pressing method, it is considered to increase the length of the drying furnace after the adhesion to obtain the drying time, but if only the drying furnace length is simply When it grows, there is a problem that color change is easily caused by thermal deterioration of the polarizer. Here, it is considered that the drying temperature is lowered so that the thermal deterioration of the polarizer does not occur, but at this time, in order to sufficiently dry, it is necessary to increase the length of the drying furnace, and the number of the drying furnace is greatly increased. The issue of investment. Further, when different types of protective films are adhered to both surfaces of the polarizing member, the shrinkage ratios due to the heat of the protective films are different, and after the shrinkage amounts of the double-sided protective films are different, the polarizing members are followed by drying. When returning to normal temperature, there is a problem that the polarizing plate is liable to curl.

In order to improve the related problems, an adhesive method by a dry lamination method is considered. However, since the viscosity of the adhesive suitable for the dry film method is extremely high, and the physical strength of the so-called polarizer is weak, the subsequent method of the polarizer and the protective film is limited to the application of the adhesive on the protective film. Then stick the method on the polarizer. In this method, when impurities are adhered to the coated surface of the adhesive before the adhesion, since the masking impurities cannot be concealed, bubbles are generated between the adhesive layer and the polarizing member starting from the impurities after the bonding, which becomes a cause of the bright spot defect. .

The inventors of the present invention have intensively studied and developed a photocurable hardenability which exhibits a good adhesion force in a short period of time when a resin film having a low moisture permeability selected from a polyester resin, a polycarbonate resin, and an acrylic resin is used as a protective film. As a result of the subsequent treatment, it was found that these protective films can be adhered in a short time by using a specific photocurable adhesive. Further, it has been found that even when an acrylic resin film is used as a protective film, the adhesive imparts a high adhesion force to the polarizer, and when a polyester resin film or a polycarbonate resin film is used as a protective film. We also exert excellent adhesions in the same way.

Accordingly, an object of the present invention is to provide a resin film having a low moisture permeability selected from a polyester resin, a polycarbonate resin, and an acrylic resin as a protective film, and also to have sufficient adhesion strength in a short time. a photocurable adhesive which is then applied to the polarizing member and does not cause problems such as poor appearance; And a polarizing plate in which the protective film is adhered to the polarizing member using the adhesive. Another object of the present invention is to provide an optical member for forming a liquid crystal display device having excellent reliability by using the polarizing plate, and to apply the optical member to a liquid crystal display device.

That is, according to the present invention, it is possible to provide a photocurable adhesive composition for use in a polarizing member made of a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed to a dichroic dye. a protective film formed of a transparent resin film selected from the group consisting of a polyester resin, a polycarbonate resin, and an acrylic resin, and an adhesive composition comprising (A) having at least a molecule in the molecule a two epoxy group epoxy compound, (B) an oxetane compound having at least one oxetanyl group in the molecule, and (C) a photocationic polymerization initiator; The weight ratio (A)/(B) of the epoxy compound (A) to the oxetane compound (B) is about 90/10 to 10/90, and the photocationic polymerization initiator (C) The amount is about 0.5 to 20% by weight in the composition.

In the photocurable adhesive composition, the epoxy compound (A) includes a compound having at least two epoxy groups and at least one aromatic ring in the molecule, specifically, having at least two epoxy groups in the molecule. a mixture of at least one aromatic ring compound, or a compound having at least two epoxy groups and at least one aromatic ring in the molecule, and a compound having at least two epoxy groups in the molecule but no aromatic ring good. In addition, the epoxy compound (A) includes one or more selected from the group consisting of glycidyl ethers and glycidyl esters of aromatic compounds, and specifically, is selected from the group consisting of aromatic compounds. One or more of the group of the glycidyl ether and the glycidyl ester, or one or more epoxy compounds selected from the group consisting of the glycidyl ether compound and the glycidyl ester compound of the aromatic compound ( The mixture of A) is more preferred.

On the other hand, as an example of the oxetane compound (B), a compound having one oxetanyl group and at least one aromatic ring in the molecule and one oxa group in the molecule are preferable. a mixture of a cyclobutyl group and at least one aromatic ring compound, a compound having at least one oxetanyl group in the molecule but not having an aromatic ring, a compound having two oxetanyl groups in the molecule, and a molecule a compound having at least two oxetanyl groups, a compound having two oxetanyl groups in the molecule, and a compound having one oxetanyl group in the molecule, and having at least two in the molecule A mixture of a compound of oxetanyl and a compound having one oxetanyl group in the molecule.

The photocurable adhesive composition may further contain, as the component (D), an unsaturated compound having at least one ethylenically unsaturated bond in the molecule, and in this case, the amount of the unsaturated compound (D) is in composition. The content is generally in the range of 35% by weight or less, preferably about 5 to 25% by weight. The unsaturated compound (D) is preferably a (meth)acrylic compound having at least one (meth)acryl fluorenyl group and at least one alicyclic backbone or aromatic ring backbone in the molecule, and further having The tricyclodecane backbone di(meth)acrylate is more preferred.

When the adhesive composition contains the above-mentioned unsaturated compound (D), particularly a (meth)acrylic compound, it is preferred to contain a photoradical polymerization initiator as the component (E). The amount of photoradical polymerization initiator (E) in the group The ratio of the product to about 10% by weight or less is preferred.

Further, the photocurable adhesive composition may contain other components which are non-polymerizable as the component (F). In this case, the amount of the other component (F) is usually about 10% by weight or less in the composition. The ratio is better.

Further, according to the present invention, it is possible to provide a polarizing plate which is formed of a polyester selected from a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed to a dichroic dye, and which is selected from a polyester via an adhesive. a polarizing plate in which a protective film made of a transparent resin film in a group of a resin, a polycarbonate resin, and an acrylic resin is adhered, and the adhesive is formed of any of the above-described photocurable adhesive compositions. .

The polarizing plate can be manufactured by a method comprising the steps of: applying an adhesive coating step of coating any one of the photocurable adhesive compositions on at least one of the adhesive faces of the polarizing member and the protective film; The adhesive layer obtained by adhering the polarizer and the protective film to the adhesive layer obtained; and the hardening step of hardening the photocurable adhesive composition in a state where the polarizer and the protective film are adhered via the adhesive layer. Specifically, after the polarizing member is coated with the unhardened photocurable adhesive composition, the protective film is adhered to the coated surface of the adhesive composition, and secondly, the adhesive composition is cured to form an adhesive. a method of laminating a polarizing member on a coated surface of the adhesive composition after applying the unhardened photocurable adhesive composition as a protective film, and then curing the adhesive composition to form an adhesive layer; Between the polarizer and the protective film, the uncured composition of the photocurable adhesive is spread, and the adhesive of the polarizer and the protective film is caught by a roller or the like, and the adhesive composition is uniformly pressed while being pressed. Combined Thereafter, a method of curing the adhesive composition to form an adhesive layer or the like is performed.

Further, according to the present invention, it is possible to provide an optical member which is provided with the above-mentioned polarizing plate and an optical layer which exhibits other optical functions. The other optical layer at this time is preferably a phase difference plate. Moreover, the present invention also provides a liquid crystal display device in which the optical member is disposed on one side or both sides of a liquid crystal cell.

The photocurable adhesive composition of the present invention has an advantage that it can be easily cured by irradiation with an active energy source such as ultraviolet rays, and the polarizer and the protective film can be consolidated in a short time. This adhesive composition is particularly useful when the protective film is formed of an acrylic resin. The polarizing plate obtained by adhering the polarizer to the protective film via the adhesive composition can be cured in a short time because the adhesive composition can be produced in a good manner. Further, an optical member obtained by combining the polarizing plate and other optical layers can form a liquid crystal display device having excellent reliability.

Hereinafter, the present invention will be described in detail. In the present invention, when a protective film made of a transparent resin film is formed on a polarizing member made of a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed to a dichroic dye, a photohardening using a specific composition is used. Sexual binder composition. The polarizer and the protective film thus formed are adhered by a photocurable adhesive composition to obtain a polarizing plate. The polarizing plate can be laminated with an optical layer having other optical functions. Into optical components. Further, the optical member is disposed on at least one side of the liquid crystal cell to form a liquid crystal display device. Hereinafter, the order of the photocurable adhesive composition, the polarizing plate, the method of producing the polarizing plate, the optical member, and the liquid crystal display device will be described one by one.

[Photocurable adhesive composition]

In the present invention, a polarizing adhesive and a protective film are adhered using a photocurable adhesive composition having a specific composition. Hereinafter, the photocurable adhesive composition may be simply referred to as a "photocurable adhesive".

The photocurable adhesive of the present invention must be one of the following three components (A), (B) and (C).

(A) an epoxy compound having at least two epoxy groups in the molecule, (B) an oxetane compound having at least one oxetanyl group in the molecule, and (C) photocationic polymerization initiation Agent.

In the present specification, the epoxy compound of the above (A) is also simply referred to as "(A) component" or "epoxy compound (A)". Similarly, in the present specification, the oxetane compound of (B) is also simply referred to as "(B) component" or "heterocyclic butane compound (B)", and the photocationic cation of (C) is also polymerized. The starting agent is simply referred to as "(C) component" or "photocationic polymerization initiator (C)".

The epoxy compound of the component (A) and the oxetane compound of the component (B) are preferably a weight ratio of (A)/(B) of from about 90/10 to about 10/90, and further, (C) The photocationic polymerization initiator of the component is preferably present in the composition in a ratio of from about 0.5 to 20% by weight.

The photocurable adhesive composition can be optionally contained as the component (D) When the unsaturated compound having at least one ethylenically unsaturated bond in the molecule contains such an unsaturated compound (D), it is preferred to contain a photoradical polymerization initiator as the component (E). Further, the photocurable adhesive may contain other components which are non-polymerizable as the component (F).

In the present specification, the unsaturated compound of the above (D) is also simply referred to as "(D) component" or "unsaturated compound (D)". Similarly, in the present specification, the photoradical polymerization initiator of (E) is also referred to as "(E) component" or "photoradical polymerization initiator (E)", and also (F) Other components that are not polymerizable are referred to as "(F) component" or "other component (F) without polymerization).

<epoxy compound (A)>

In the photocurable adhesive of the present invention, the epoxy compound which is the component (A) is not particularly limited as long as it has at least two epoxy groups in the molecule, and various conventional hardening epoxy resins can be used. Compound. Preferred examples of the epoxy compound which is the component (A) include a compound having at least two epoxy groups and at least one aromatic ring in the molecule (hereinafter referred to as "aromatic epoxy compound"). Or at least two epoxy groups in the molecule, and at least one of them is a compound formed between two adjacent carbon atoms constituting the alicyclic ring (hereinafter referred to as "alicyclic epoxy compound").

The aromatic epoxy compound is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and brominated double a bisphenol type epoxy resin such as bisphenolate ether of phenol A; a phenol novolac type epoxy resin such as a phenol novolac type epoxy resin; and a cresol novolac type epoxy resin such as a phenol novolac type epoxy resin; Can be cited: biphenyl type epoxy resin, para-benzene Diphenol diglycidyl ether, resorcinol diglycidyl ether, diglycidyl terephthalate, diglycidyl phthalate, epoxide of styrene-butadiene copolymer, styrene - An epoxide of an isoprene copolymer, an addition reaction of a terminal carboxylic acid polybutadiene and a bisphenol A type epoxy resin, and the like.

Here, the epoxy resin means a compound or a polymer having an average of two or more epoxy groups in a molecule and which is hardened by a reaction. According to the practice in the field, in the present specification, even if it is a monomer having two or more curable epoxy groups in the molecule, even a monomer is called an epoxy resin.

The alicyclic epoxy compound is not particularly limited as long as it does not impair the effects of the present invention, and examples thereof include dicyclopentadiene dioxide, limonene dioxide, and 4-vinylcyclohexene dioxide. 3,4-epoxycyclohexanecarboxylic acid 3,4-epoxycyclohexylmethyl ester, and bis(3,4-epoxycyclohexylmethyl) adipate have at least one ring A compound which oxidizes a cyclohexyl group or the like.

In addition to the above, the epoxy compound of the component (A) may also be exemplified by 1,6-hexanediol diglycidyl ether, trimethylolpropane triglycidyl ether, pentaerythritol tetraglycidyl ether, and polytetramethylene. An aliphatic epoxy compound such as a diol diglycidyl ether; an aromatic ring hydrogenated epoxy compound such as hydrogenated bisphenol A diglycidyl ether; and both ends of the polybutadiene having a hydroxyl group at both terminals are glycidol An etherified compound, an internal epoxide of polybutadiene, a compound in which a double bond of a styrene-butadiene copolymer is partially epoxidized [for example, "Epoblend" manufactured by Daicel Chemical Industry Co., Ltd.], and A polymer-based ring of a compound in which an isoprene unit of an ethylene-butene copolymer and a polyisoprene block copolymer is partially epoxidized (for example, " L-207 " manufactured by KRATON Co., Ltd.) Oxygen compounds, etc.

Among them, the aromatic epoxy compound is excellent in durability when it is used as a polarizing plate, and is particularly excellent in adhesion to a polarizer and a protective film. Further, as the aromatic epoxy compound, a glycidyl ether of an aromatic compound or a glycidyl ester of an aromatic compound may, for example, be mentioned. Specific examples of the glycidyl ether of the aromatic compound include bisphenols such as bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and brominated bisphenol A diglycidyl ether. Type epoxy resin; such as phenol novolak type epoxy resin, and phenol novolak type epoxy resin and other novolac type epoxy resin; biphenyl type epoxy resin; hydroquinone diglycidyl ether; isophthalic acid Phenol diglycidyl ether and the like. Further, specific examples of the glycidyl ester of the aromatic compound include diglycidyl terephthalate and diglycidyl phthalate.

Among them, the diglycidyl ether of the aromatic compound is particularly excellent because it is excellent in adhesion at the time of following the polarizer and the protective film or when it is used as a polarizing plate. Among the diglycidyl ethers of the aromatic compound, particularly preferred are bisphenol A diglycidyl ether, bisphenol F diglycidyl ether, and phenol novolac type epoxy resin.

The epoxy compound of the component (A) may be used singly or in combination of two or more. For example, two or more kinds of aromatic epoxy compounds may be used in combination, and an aromatic epoxy compound may be mainly used as a main component and mixed with an alicyclic epoxy compound.

<oxetane compound (B)>

In the photocurable adhesive of the present invention, the oxetane compound which is the component (B) is any one having at least one oxetanyl group in the molecule. It is not particularly limited, and various compounds having an oxetanyl group can be used. Preferred examples of the oxetane compound (B) include a compound having one oxetanyl group in the molecule (hereinafter simply referred to as "monofunctional oxetane"), and a molecule. A compound having two or more oxetanyl groups (hereinafter simply referred to as "polyfunctional oxetane").

Preferred examples of the monofunctional oxetane include a monofunctional group containing an alkoxyalkyl group such as 3-ethyl-3-(2-ethylhexyloxymethyl)oxetane or the like. An oxetane; an aromatic group-containing monofunctional oxetane such as 3-ethyl-3-phenoxymethyloxetane; such as 3-ethyl-3-hydroxymethyl oxygen A monofunctional oxetane having a hydroxyl group such as a heterocyclobutane or the like.

As the polyfunctional oxetane, a compound such as 3-ethyl-3-[(3-ethyloxetan-3-yl)methoxymethyl]oxetane can be exemplified. Alkane, 1,4-bis[(3-ethyloxetan-3-yl)methoxymethyl]benzene, 1,4-bis[(3-ethyloxetane-3- Methoxy]benzene, 1,3-bis[(3-ethyloxetan-3-yl)methoxy]benzene, 1,2-bis[(3-ethyloxetane) Alkyl-3-yl)methoxy]benzene, 4,4'-bis[(3-ethyloxetan-3-yl)methoxy]biphenyl, 2,2'-bis[(3) -ethyloxetan-3-yl)methoxy]biphenyl, 3,3',5,5'-tetramethyl-4,4'-bis[(3-ethyloxetine) Alkyl-3-yl)methoxy]biphenyl, 2,7-bis[(3-ethyloxetan-3-yl)methoxy]naphthalene, bis[4-{(3-ethyl) Oxetane-3-yl)methoxy]phenyl}methane, bis[2-{(3-ethyloxetan-3-yl)methoxy]phenyl}methane, 2, 2-bis[4-{(3-ethyloxetan-3-yl)methoxy]phenyl}propane, 3-chloromethyl-3-ethyloxy of novolac type phenol-formaldehyde resin Etherification modification of heterocyclobutane, 3(4),8(9)-bis[(3-ethyloxetan-3-yl)methoxymethyl]-tricyclo[5.2.1.0 ^2,6] decane 2,3-bis[(3-ethyloxetan-3-yl)methoxymethyl]norbornane, 1,1,1-gin[(3-ethyloxetane- 3-yl)methoxymethyl]propane, 1-butoxy-2,2-bis[(3-ethyloxetan-3-yl)methoxymethyl]butane, 1, 2-bis[{2-(3-ethyloxetan-3-yl)methoxy}ethylthio]ethane, bis[{4-(3-ethyloxetane-3) -yl)methylthio}phenyl]sulfide, 1,6-bis[(3-ethyloxetan-3-yl)methoxy]-2,2,3,3,4,4 , 5,5-octafluorohexane, 3-[(3-ethyloxetan-3-yl)methoxy]propyltriethoxydecane hydrolysis condensate, 肆[(3-B A condensate of oxetane-3-yl)methyl]decanoate or the like.

The oxetane compound of the component (B) is preferably a liquid having a molecular weight of 500 or less at room temperature from the viewpoints of workability or adhesion to a protective film when a polarizing plate is formed. Further, from the viewpoint that the polarizing plate is excellent in durability, it is more preferable that the monofunctional oxetane has an aromatic ring in the molecule or a polyfunctional oxetane. As an example of such a particularly preferred oxetane compound, for example, 3-ethyl-3-phenoxymethyloxetane, 3-ethyl-3-[(3-ethyl) Oxetane-3-yl)methoxymethyl]oxetane, and 1,4-bis[(3-ethyloxetan-3-yl)methoxymethyl Base] benzene and so on.

The oxetane compound of the component (B) may be used alone or in combination of two or more.

<ratio of epoxy compound (A) to oxetane compound (B)>

The use ratio of the epoxy compound of the component (A) to the oxetane compound of the component (B) is 90/10 to 10/90 by weight ratio of (A)/(B). When the ratio is too large or insufficient, the effect of short-time hardening which is one of the important characteristics of the photocurable adhesive of the present invention cannot be sufficiently exerted. Since the preferred weight ratio of the two is excellent in coatability at low viscosity before hardening and sufficient adhesion and flexibility after hardening, the preferred weight ratio of the two is 70/30 to 20 /80 or so, the better weight ratio is around 60/40 to 25/75.

<Photocationic polymerization initiator (C)>

The photocurable adhesive of the present invention contains the epoxy compound (A) and the oxetane compound (B) described above as a curing component, and since these are all cured by cationic polymerization, blending is used as A photocationic polymerization initiator of the component (C). The photocationic polymerization initiator generates a cationic species or a Lewis acid by irradiation with an active energy source such as visible light, ultraviolet rays, X-rays, or electron beams to initiate polymerization of an epoxy group or an oxetane group.

By blending the photocationic polymerization initiator as the component (C), it can be hardened at room temperature, thereby reducing the necessity of considering the heat resistance of the polarizer or the skew caused by expansion or contraction, and allowing the protective film to be provided. Good to follow. Moreover, the photocationic polymerization initiator is acted as a catalyst due to irradiation of an active energy source. Since it is mixed with the epoxy compound (A) and the oxetane compound (B), it is excellent in storage stability and workability. Examples of the compound which generates a cationic species or a Lewis acid by irradiation with an active energy source include a sulfonium salt such as an aromatic diazonium salt, an aromatic sulfonium salt or an aromatic sulfonium salt, and an iron-propylene hydride. Ole complex and the like.

Examples of the aromatic diazonium salt include compounds such as benzenediazonium hexafluoroantimonate, benzenediazonium hexafluorophosphate, and benzenediazonium hexafluoroborate.

Examples of the aromatic onium salt include compounds of diphenylphosphonium sulfonium (pentafluorophenyl)borate, diphenylphosphonium hexafluorophosphate, diphenylphosphonium hexafluoroantimonate, and hexafluorophosphoric acid. Bis(4-nonylphenyl) phosphonium salt and the like.

Examples of the aromatic onium salt include the following compounds: triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium sulfonate (pentafluorophenyl)borate, and hexafluorophosphoric acid. Diphenyl[4-(phenylthio)phenyl]phosphonium salt, diphenyl[4-(phenylthio)phenyl]phosphonium hexafluoroantimonate, 4,4'-bis(diphenylfluorenyl) Diphenyl sulfide dihexafluorophosphate, 4,4'-bis[bis(β-hydroxyethoxy)phenylindenyl]diphenyl sulfide dihexafluoroantimonate, 4,4'- Bis[di(β-hydroxyethoxy)phenylindenyl]diphenyl sulfide dihexafluoro Phosphate, 7-[bis(p-tolyl)indolyl]-2-isopropylthioxanthone hexafluoroantimonate, 7-[bis(p-tolyl)indolyl]-2-isopropylthioxanthene Ketooxime (pentafluorophenyl)borate, 4-phenylcarbonyl-4'-diphenylfluorenyl-diphenyl sulfide hexafluorophosphate, 4-(p-t-butylphenylcarbonyl)- 4'-diphenylindenyl-diphenyl sulfide hexafluoroantimonate, 4-(p-t-butylphenylcarbonyl)-4'-di(p-tolyl)indenyl-diphenylsulfide Ether quinone (pentafluorophenyl) borate or the like.

As the iron-propylene complex, for example, the following compounds may be mentioned: xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate Salt, xylene-cyclopentadienyl iron (II)-parafic (trifluoromethylsulfonyl) methylate, and the like.

These photocationic polymerization initiators may be used alone or in combination of two or more. Among them, the aromatic sulfonium salt is particularly suitable for use because it has ultraviolet absorbing properties even in a wavelength region of 300 nm or more, and thus can be provided with a cured product having excellent hardenability, good mechanical strength, or adhesion strength.

The photocationic polymerization initiator can be easily obtained from commercially available products, and can be listed by brand names such as "Kayarad PCI-220", "Kayarad PCI-620" (above, manufactured by Nippon Kayaku Co., Ltd.), "UVI". -6992" (made by Dow Chemical Co., Ltd.), "ADEKA OPTOMER SP-150", "ADEKA OPTOMER SP-170" (above, ADEKA (share) system), "CI-5102", "CIT-1370", "CIT -1682", " CIP-1866S", "CIP-2048S", "CIP-2064S" (above, Japanese Soda (share) system), "DPI-101", "DPI-102", "DPI-103", "DPI-105", "MPI-103", "MPI-105", "BBI-101", "BBI-102", "BBI-103", "BBI-105", "TPS-101", "TPS -102", "TPS-103", "TPS-105", "MDS-103", "MDS-105", "DTS-102", "DTS-103" (above, Green Chemical Co., Ltd.), "PI-2074" (made by RHODIA), "Irgacure 250", "Irgacure PAG 103", "Irgacure PAG 108", "Irgacure PAG 121", "Irgacure PAG 203" (above, Ciba), "CPI -100P", "CPI-101A", "CPI-200K", "CPI-210S" (above, San-Apro), especially containing diphenyl[4-(phenylthio)phenyl "UVI-6992" manufactured by The Dow Chemical Co., Ltd., which is a cationic component, and San-Apro (share) system "CPI-100P", "CPI-101A", "CPI-200K", "CPI-210S" is better.

The blending ratio of the photocationic polymerization initiator of the component (C) is in the range of 0.5 to 20% by weight based on the entire photocurable adhesive. When the ratio is less than 0.5% by weight, the hardening of the adhesive becomes insufficient, and the mechanical strength or the subsequent strength decreases. On the other hand, when the ratio exceeds 20% by weight, the ionic substance in the cured product increases to cause the hardened material to be sucked. The wetness becomes high and the durability may be lowered.

<unsaturated compound (D)>

In the photocurable adhesive of the present invention, if necessary, an unsaturated compound having at least one ethylenically unsaturated bond in the molecule as the component (D) may be contained. A typical example of the unsaturated compound (D) is a (meth)acrylic compound having at least one (meth)acryl fluorenyl group in the molecule.

The (meth)acrylic compound is not particularly limited, and examples thereof include (meth)acrylates, (meth)acrylamides, and (meth)acryls. Acid, (meth) propylene decylmorpholine, (meth) acrolein, and the like.

The (meth) acrylate having one (meth) acrylonitrile group in the molecule (hereinafter, simply referred to as a monofunctional (meth) acrylate) is not particularly limited, and examples thereof include the following compounds: Such as methyl (meth) acrylate, ethyl (meth) acrylate, propyl (meth) acrylate, isopropyl (meth) acrylate, butyl (meth) acrylate, isobutyl (meth) acrylate , 2-ethylhexyl (meth)acrylate, octyl (meth)acrylate, isooctyl (meth)acrylate, lauryl (meth)acrylate, and stearyl (meth)acrylate (A Alkyl acrylates; such as 2-hydroxyethyl (meth)acrylate, 2-hydroxypropyl (meth)acrylate, and 4-hydroxybutyl (meth)acrylate, etc. Such as cyclohexyl (meth)acrylate, isobornyl (meth)acrylate, 1,4-cyclohexanedimethylol mono(meth)acrylate, dicyclopentanyl (meth)acrylate, An alicyclic monofunctional (meth) acrylate such as dicyclopentenyl (meth) acrylate or dicyclopentenyloxyethyl (meth) acrylate; such as benzyl (meth) acrylate, dimorphism Propyl phenol epoxy (meth) acrylate of an adduct, (meth) acrylate of an o-phenylphenol alkylene oxide adduct, a (meth) acrylate of a phenol alkylene oxide adduct, and a nonyl phenol epoxy a monofunctional (meth) acrylate having an aromatic ring such as a (meth) acrylate of an alkane adduct (herein, an alkylene oxide may, for example, ethylene oxide or propylene oxide); a (meth)acrylic acid alkoxylate such as 2-methoxyethyl acrylate, ethoxymethyl (meth) acrylate, and (meth) acrylate of an alkylene oxide adduct of 2-ethylhexyl alcohol Alkyl esters; Such as ethylene glycol mono (meth) acrylate, propylene glycol mono (meth) acrylate, pentanediol mono (meth) acrylate, and hexanediol mono (meth) acrylate and other glycols (A Acrylates; such as diethylene glycol mono (meth) acrylate, triethylene glycol mono (meth) acrylate, tetraethylene glycol mono (meth) acrylate, polyglycol mono a polyalkylene glycol mono(meth)acrylate such as acrylate, dipropylene glycol mono(meth)acrylate, tripropylene glycol mono(meth)acrylate, and polypropylene glycol mono(meth)acrylate; Glycidyl methacrylate; tetrahydrofuran (meth) acrylate; such as caprolactone modified tetrahydrofuranyl (meth) acrylate such as tetrahydrofurfuryl (meth) acrylate; 3,4-epoxy (meth) acrylate Base cyclohexyl methyl ester; N,N-dimethylaminoethyl (meth)acrylate; 2-(methyl)propenyloxyethyl isocyanate.

Further, the (meth) acrylate having two or more (meth) acryl fluorenyl groups in the molecule is not particularly limited, and examples thereof include compounds such as tricyclodecane dimethylol bis ( Methyl) acrylate, 1,4-cyclohexane dimethylol di(meth) acrylate, norbornane dimethylol di(meth) acrylate, and hydrogenated bisphenol A bis (methyl) a di(meth)acrylate having an alicyclic ring such as an acrylate; such as a di(meth)acrylate containing a bisphenol A ethylene oxide adduct and a bisphenol A propylene oxide adduct a di(meth)acrylate of a bisphenol A alkylene oxide adduct of di(meth)acrylate, and a di(meth)acrylate of bisphenol A diglycidyl ether, etc. (meth)acrylates; such as ethylene glycol di(meth)acrylate, propylene glycol di(meth)acrylate, pentanediol di(meth)acrylate, and hexanediol di(meth)acrylic acid Alkylene glycol di(meth)acrylates such as esters; diethylene glycol di(meth)acrylate, triethylene glycol di(meth)acrylate, tetraethylene glycol di(meth)acrylate, Polyethylene glycol II Polyalkylene glycol di(meth)acrylates such as acrylate, dipropylene glycol di(meth)acrylate, tripropylene glycol di(meth)acrylate, and polypropylene glycol di(meth)acrylate; glycerin Di- or tri(meth)acrylates of glycerol such as di- or tri-(meth)acrylate, di- or tri-(tri)glycerol; glycerol-based alkylene oxide adduct Or tris(meth)acrylates; bisphenols such as bis(meth)acrylates of bisphenol A alkylene oxide adducts and bis(meth)acrylates of bisphenol F alkylene oxide adducts Dialkyl (meth) acrylates of alkylene oxide adducts; such as trimethylolpropane tri(meth)acrylate, di(trimethylolpropane)tri(meth)acrylate, di(tris) Methylpropane) tetra (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, dipentaerythritol penta (meth) acrylate, dipentaerythritol hexa (meth) acrylate, etc. Polyol (meth) acrylates; poly(meth) acrylates of alkylene oxide adducts of such polyols; diisocyanate alkylene oxide adducts Or tris(meth)acrylates; 1,3,5-tris(methyl)propenylfluorenylhexahydro-s-three Wait.

Examples of the (meth)acrylamides include (meth)acrylamide, N,N-dimethyl(meth)acrylamide, and N,N-diethyl(meth)propene. Indoleamine, N-methylol (meth) acrylamide, N-(3-N,N-dimethylaminopropyl)(methyl) acrylamide, methylene bis(methyl) propylene Indoleamine, ethyl bis(methyl) acrylamide and the like.

Further, an oligomer such as an amine ester (meth) acrylate, a polyester (meth) acrylate or an epoxy (meth) acrylate may be used as the (meth)acrylic compound.

Further, a compound having a (meth)acryloyl group and an ethylenically unsaturated bond at the same time may be used as the (meth)acrylic compound, and specific examples thereof include allyl (meth)acrylate. N,N-diallyl (meth) acrylamide and the like.

The component (D) is not particularly limited, and other than the above (meth)acrylic compound, for example, N-vinyl-2-pyrrolidone, divinyl adipate, and diammonium dicarboxylate may be used. a vinyl compound such as an ester; such as triallyl cyanurate, triallylamine, tetraallyl pyromellitate, N, N, N'N'-tetraallyl-1,4- An allyl compound such as a diaminobutane, a tetraallyl ammonium salt or an allylamine; an unsaturated carboxylic acid such as maleic acid or itaconic acid.

Even in the unsaturated compound of the component (D), a (meth)acrylic compound is preferred. Further, when the polarizer and the protective film are subsequently formed as a polarizing plate via an adhesive containing the compound, at least one alicyclic bone is contained in the molecule from the viewpoint of improving durability such as heat resistance. A (meth)acrylic compound of a dry or aromatic ring backbone is preferred. Specific examples of the (meth)acrylic compound having at least one alicyclic backbone or aromatic ring backbone in the molecule, and preferred examples thereof include the aforementioned alicyclic monofunctional (meth)acrylates, and A monofunctional (meth) acrylate of an aromatic ring, a di(meth) acrylate having an alicyclic ring, and a di(meth) acrylate having an aromatic ring. Among these, a di(meth)acrylate having a tricyclodecane backbone is also preferred, and specific examples of such a particularly preferred (meth)acrylic compound include tricyclodecane dimethylol. Di(meth)acrylate and the like.

In order to adjust the curing rate, the adhesion between the polarizer and the protective film, the elastic modulus of the adhesive layer, or the durability of the adhesive, an unsaturated compound of the component (D) can be used. The unsaturated compound of the component (D) may be used singly or in combination of two or more.

When the unsaturated compound of the component (D) is blended, the blending ratio is preferably 35% by weight or less based on the entire composition. Thereby, it is excellent in the adhesiveness of a polarizer and a protective film. When the amount of the unsaturated compound (D) exceeds 35% by weight, sufficient adhesion strength is not easily obtained with the polarizer. Therefore, the blending ratio of the unsaturated compound (D) is preferably 30% by weight or less, more preferably 5 to 25% by weight, still more preferably 10 to 20% by weight.

<Photoradical polymerization initiator (E)>

When the photocurable adhesive of the present invention contains the unsaturated compound of the component (D), in order to promote the radical polymerizability and to sufficiently accelerate the curing rate, the photoradical polymerization initiator as the component (E) is blended. good.

The specific example of the photoradical polymerization initiator of the component (E) is not particularly limited, and examples thereof include compounds such as 4'-phenoxy-2,2-dichloroacetophenone and 4'-. Third butyl-2,2-dichloroacetophenone, 2,2-dimethoxy-2-phenylacetophenone, 2-methyl-1-(4-methylthiophenyl)-2 -morpholinylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, α,α-diethoxyacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1-(4-isopropylphenyl)-2-hydroxy-2-methylpropan-1-one, 1-(4-dodecylphenyl)-2-hydroxy-2-methylpropane-1 -ketone, 1-[4-(2-hydroxyethoxy)phenyl]-2-hydroxy-2-methylpropan-1-one, and 2-benzyl-2-dimethylamino-1- Acetophenone photopolymerization initiator such as (4-morpholinylphenyl)butan-1-one; such as benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl a phenylene ether ether photopolymerization initiator such as phenyl ether and benzoin isobutyl ether; such as benzophenone, methyl o-benzhydryl benzoate, 4-phenylbenzophenone, 4 a benzophenone-based photopolymerization initiator such as benzhydryl-4'-methyldiphenyl sulfide or 2,4,6-trimethylbenzophenone; Such as 2-isopropylthioxanthone, 2,4-diethylthioxanthone, 2,4-bicyclothioxanthone, and 1-chloro-4-propoxythioxanthone and other thioxanthone (thioxanthone) a photopolymerization initiator; such as 2,4,6-trimethylbenzimidyldiphenylphosphine oxide, bis(2,6-dimethoxybenzylidene)-2,4,4 - a mercaptophosphine oxide photopolymerization initiator such as trimethylpentylphosphine oxide or bis(2,4,6-trimethylbenzylidene)phenylphosphine oxide; such as 1,2- Octanedione, 1-[4-(phenylthiophenyl)]-, 2-(O-benzylidene fluorene), 1,2-octanedione, 1-[4-(phenylthiophenyl)]-, 2 -(O-benzoyloxim e)) Equivalent ‧ ester photopolymerization initiator; camphorquinone and the like.

The photoradical polymerization initiator of the component (E) may be used singly or in combination of two or more kinds depending on the desired properties. When the photo-radical polymerization initiator of the component (E) is blended, the blending ratio is preferably 10% by weight or less, and more preferably 0.1% to 3% by weight based on the entire composition. When the amount of the photoradical polymerization initiator (E) is too large, sufficient strength cannot be obtained, and when the amount is insufficient, the binder is not sufficiently cured.

<Other ingredients>

Further, in the photocurable adhesive of the present invention, other components different from the components (A) to (E) described above may be optionally blended insofar as the effects of the present invention are not impaired. The type which is one of such other components may be a compound having a cationic polymerizable property other than the epoxy compound of the component (A) or the oxetane compound of the component (B). The specific example is not particularly limited, and examples thereof include an epoxy compound having one epoxy group in the molecule. Further, as another type of other components, other components (F) which are not polymerizable may be mentioned. When the other component (F) having no polymerizable property is blended, the blending ratio is preferably about 10% by weight or less based on the entire composition.

The example of the other component (F) which is not polymerizable is not particularly limited, and examples thereof include a photosensitizer. By blending a light sensitizer, the reactivity can be improved and the mechanical strength or strength of the cured product can be increased. Examples of the photosensitizer include a carbonyl compound, an organic sulfur compound, a persulfide compound, a redox compound, an azo and a diazo compound, a halogen compound, and a photoreductive dye.

The specific light sensitizer is not particularly limited, and examples thereof include compounds such as benzoin methyl ether, benzoin isopropyl ether, and α,α-dimethoxy-α-benzene. Benzoin derivatives such as acetophenone; such as benzophenone, 2,4-dichlorobenzophenone, o-benzhydryl benzoic acid methyl ester, 4,4'-bis(dimethylamine) a benzophenone derivative such as benzophenone and 4,4'-bis(diethylamino)benzophenone; such as 2-chlorothioxanthone and 2-isopropylthioxanthone a thioxanthone derivative; an anthracene derivative such as 2-chloroindole and 2-methylindole; others such as α,α-diethoxyacetophenone, benzil, and hydrazine Ketone, xanthone, uranyl compound, halogen compound, and the like.

In addition, although the compound corresponding to the photo-radical polymerization initiator of the above-mentioned (E) component is also used, the photo-sensitizer as described above has a photocationic polymerization initiator as the component (C). The function of the sensitizer is not particularly limited. These may be used alone or in combination of two or more.

a cationic monomer in the photocurable adhesive of the present invention [containing the aforementioned epoxy compound (A) and oxetane compound (B), and when blended with the other compound having the above cationicity When the total amount of the compound is also included as 100 parts by weight, it is preferred to contain the photosensitizer in an amount of 0.1 to 20 parts by weight.

Further, as the other component (F) having no polymerizable property, a thermal cationic polymerization initiator can also be used. As a thermal cationic polymerization initiator, benzyl A sulfonium salt, a thiophenium salt, a thiolanium salt, a benzyl ammonium salt, a pyridinium salt, a hydrazinium salt, a carboxylic acid ester, a sulfonate, an amine imine or the like. Such a starter can be easily obtained from a commercially available product, and is, for example, a trade name product, and examples thereof include "ADEKA OPTON CP77" and "ADEKA OPTON CP66" (above, ADEKA (share) system), "CI-2639" ", and "CI-2624" (above, Japan's Soda (share) system), "San Aid SI-60L", "San Aid SI-80L", and "San Aid SI-100L" (above, Sanxin Chemical Industry) (share) system, etc.

Since the polyol has a property of promoting cationic polymerization, it can also be used as the other component (F) having no polymerizability. The polyol is preferably an acid group other than the phenolic hydroxyl group, and examples thereof include a polyol compound having no functional group other than a hydroxyl group, a polyester polyol compound, a polycaprolactone polyol compound, and a phenol. A polyol compound of a hydroxyl group, a polycarbonate polyol compound, or the like.

Further, insofar as the effects of the present invention are not impaired, the following may be blended as the other component (F) having no polymerizability: a decane coupling agent, an ion scavenger, an antioxidant, a photostabilizer, a bond transfer agent, Sensitizer, adhesion-imparting agent, thermoplastic resin, filler, flow regulator, plasticizer, antifoaming agent, coating agent, coloring matter, organic solvent, and the like. It is also effective to blend a thermoplastic resin as the other component (F) having no polymerity for the purpose of further improving the adhesion to the protective film. From the viewpoint of improving the durability of the polarizing material, the thermoplastic resin is preferably a glass transition temperature of 70 ° C or higher, and a particularly preferable example is a methyl methacrylate polymer.

[Polarizer]

The photocurable adhesive agent described above is used for adhering a protective film to a polarizing member made of a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed to a dichroic dye, and is pasted on such a polarizing member. The protective film becomes a polarizing plate. In other words, the polarizing plate of the present invention is not particularly limited as long as it is adhered to a polarizing member made of a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed to the dichroic dye. The protective film can be adhered only to one side of the polarizing member or to both sides of the polarizing member. When the protective film is adhered to both sides of the polarizing member, each of the protective films may be made of the same kind of resin or may be made of different kinds of resins.

<polarizer>

The polyvinyl alcohol-based resin constituting the polarizer is obtained by saponifying a polyvinyl acetate-based resin. As the polyvinyl acetate-based resin, a polyvinyl acetate of a vinyl acetate alone polymer, a copolymer of vinyl acetate and another monomer copolymerizable therewith, and the like can be exemplified. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, olefins, vinyl ethers, and unsaturated sulfonic acids. The degree of saponification of the polyvinyl alcohol-based resin is not particularly limited and is usually from 85 to 100 mol%, preferably from 98 to 100 mol%. The polyvinyl alcohol-based resin may be further modified. For example, polyvinyl formal or polyvinyl acetal modified with an aldehyde may be used. The degree of polymerization of the polyvinyl alcohol-based resin is not particularly limited, but is usually from 1,000 to 10,000, and preferably from 1,500 to 10,000.

The polarizing plate is produced by the step of uniaxially stretching such a polyvinyl alcohol-based resin film; and the polyvinyl alcohol-based resin film is a step of dyeing the dichroic dye and adsorbing the dichroic dye; a step of treating the polyvinyl alcohol-based resin film having the dichroic dye adsorbed thereon with a boric acid aqueous solution; and performing a water washing step after the treatment with the aqueous boric acid solution; After performing the above steps, the protective film is adhered to the uniaxially stretched polyvinyl alcohol-based resin film by adsorption-alignment of the dichroic dye.

The uniaxial stretching may be carried out before the dyeing by the dichroic dye, or simultaneously by the dyeing with the dichroic dye, or after the dyeing by the dichroic dye. When uniaxial stretching is performed after dyeing by a dichroic dye, the uniaxial stretching can be carried out before the boric acid treatment, or in the boric acid treatment. In addition, it is of course also possible to perform uniaxial stretching in these plurality of stages. The uniaxial extension can be uniaxially extended between rolls having different peripheral speeds, or can be uniaxially extended using a hot roll. Further, it may be a dry stretching which is extended in the atmosphere, or may be a wet stretching which is extended in a state of being swollen by a solvent. The stretching ratio is not particularly limited and is usually about 4 to 8 times.

When the polyvinyl alcohol-based resin film is dyed with a dichroic dye, for example, the polyvinyl alcohol-based resin film may be immersed in an aqueous solution containing a dichroic dye, and the dichroic dye is specifically iodine or two. Color dyes.

When iodine is used as the dichroic dye, a method in which a polyvinyl alcohol-based resin film is immersed in an aqueous solution containing iodine and potassium iodide and dyed is usually used. The content of iodine in the aqueous solution is not particularly limited, and is usually about 0.01 to 0.5 parts by weight per 100 parts by weight of water, and the content of potassium iodide is not particularly limited, and is usually about 0.5 to 10 parts by weight per 100 parts by weight of water. . The temperature of the aqueous solution is not particularly limited, but is usually about 20 to 40 ° C. Further, the immersion time of the aqueous solution is not particularly limited, and is usually 30 to About 300 seconds.

On the other hand, when a dichroic dye is used as a dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic dye and dyeing it is usually employed. The content of the dichroic dye in the aqueous solution is not particularly limited, but is usually about 1 × 10 ^-3 to 1 × 10 ^-2 parts by weight per 100 parts by weight of water. The aqueous solution may also contain an inorganic salt such as sodium sulfate. The temperature of the aqueous solution is not particularly limited, but is usually about 20 to 80 ° C. Further, the immersion time of the aqueous solution is not particularly limited, but is usually about 30 to 300 seconds.

After the dyeing by the dichroic dye, the boric acid treatment is carried out by immersing the dyed polyvinyl alcohol-based resin film in an aqueous boric acid solution. The content of boric acid in the aqueous boric acid solution is not particularly limited, but is usually about 2 to 15 parts by weight, preferably about 5 to 12 parts by weight, per 100 parts by weight of water. When iodine is used as the dichroic dye, the aqueous boric acid solution preferably contains potassium iodide. The content of potassium iodide in the aqueous boric acid solution is not particularly limited, but is usually about 2 to 20 parts by weight, preferably about 5 to 15 parts by weight, per 100 parts by weight of water. The immersion time of the aqueous boric acid solution is not particularly limited, but is usually about 100 to 1,200 seconds, preferably about 150 to 600 seconds, more preferably about 200 to 400 seconds. The temperature of the aqueous boric acid solution is not particularly limited, and is usually 50 ° C or higher, preferably about 50 to 85 ° C.

The polyvinyl alcohol-based resin film after boric acid treatment is usually subjected to a water washing treatment. The water washing treatment is performed, for example, by immersing a boric acid-treated polyvinyl alcohol-based resin film in water. After washing with water, drying treatment was carried out to obtain a polarizing member. In the water washing treatment, the temperature of the water is not particularly limited, and is usually 5 ° C to 40 ° C or so. The immersion time is not particularly limited, but is usually about 2 to 120 seconds, and the drying treatment thereafter is usually carried out using a hot air dryer or a far infrared ray heater. The drying temperature is not particularly limited and is usually from 40 ° C to 100 ° C. The treatment time of the drying treatment is not particularly limited and is usually about 120 to 600 seconds.

Therefore, a polarizer comprising a polyvinyl alcohol-based resin film which is adsorbed and aligned as an iodine or a dichroic dye of a dichroic dye is obtained.

<Protective film>

Next, the polarizing member is adhered to the protective film on one or both sides thereof using the photocurable adhesive described above. The triethylenesulfonyl cellulose film which has been widely used as a protective film for a polarizer has a moisture permeability of about 400 g/m ² /24 hours, but in the present invention, at least one side of the polarizing member is pasted. The protective film is a resin which exhibits a lower moisture permeability than the triacetyl cellulose, and is a polyester resin, a polycarbonate resin or an acrylic resin.

The type of the polyester resin used for the protective film is not particularly limited, and polyethylene terephthalate is particularly preferable in terms of mechanical properties, solvent resistance, scratch resistance, cost, and the like. . The polyethylene terephthalate refers to a resin composed of 80 mol% or more of repeating units of ethylene terephthalate, and may also contain constituent units derived from other copolymerized components. As other copolymerization components, preferred examples are: isophthalic acid, p-β-hydroxyethoxybenzoic acid, 4,4'-dicarboxydiphenyl, 4,4'-dicarboxydiphenyl Methyl ketone, bis(4-carboxyphenyl)ethane, adipic acid, sebacic acid, sodium 5-sulfoisophthalate, and 1,4-dicarboxycyclohexane a dicarboxylic acid component such as an alkane; for example, propylene glycol, butylene glycol, neopentyl glycol, diethylene glycol, cyclohexanediol, ethylene oxide adduct of bisphenol A, polyethylene glycol, polypropylene glycol, and poly A diol component such as tetramethylene glycol. These dicarboxylic acid components or diol components can be used in combination of two or more types as needed. Further, the above dicarboxylic acid component, diol component, and hydroxycarboxylic acid such as p-hydroxybenzoic acid may be used in combination. A dicarboxylic acid component and/or a diol component having a guanamine bond, an amine ester bond, an ether bond, a carbonate bond or the like may be used in a small amount as another copolymerization component.

The method for producing the polyester resin may be any one of the following methods: a direct polymerization method in which terephthalic acid and ethylene glycol (further depending on other dicarboxylic acid components and/or diol components required) are directly reacted, A so-called transesterification reaction method in which a dimethyl ester of terephthalic acid is subjected to a transesterification reaction with ethylene glycol (further depending on a desired dimethyl ester of a dicarboxylic acid component and/or other diol component). Further, the polyester resin may contain a conventional additive as needed. The additive which can be contained is not particularly limited, and examples thereof include a lubricant, an antiblocking agent, a thermal stabilizer, an antioxidant, an antistatic agent, a light stabilizer, and an impact resistance improver. However, since the protective film laminated on the polarizing film requires transparency, the amount of such additives is preferably minimized.

The raw material resin is formed into a film shape, and by performing uniaxial stretching or biaxial stretching treatment, a protective film made of the stretched polyester resin can be produced. By performing the stretching treatment, a film having high mechanical strength can be obtained. The method for producing the stretched polyester resin film is not particularly limited, and examples thereof include a non-alignment in which the raw material resin is melted and extruded into a sheet shape. The film is subjected to a heat setting treatment after being laterally stretched by a tenter at a temperature higher than the glass transition temperature.

Preferred examples of the polycarbonate resin used for the protective film include polyesters formed of carbonic acid and a glycol or bisphenol. Among them, an aromatic polycarbonate having a diphenyl alkane in a molecular chain is preferably used because it is excellent in heat resistance, weather resistance, and acid resistance. As such a polycarbonate, it can be exemplified by, for example, 2,2-bis(4-hydroxyphenyl)propane (alias bisphenol A), 2,2-bis(4-hydroxyphenyl)butane, 1, Bisphenols such as 1-bis(4-hydroxyphenyl)cyclohexane, 1,1-bis(4-hydroxyphenyl)isobutane, or 1,1-bis(4-hydroxyphenyl)ethane Derived polycarbonate.

As a method of producing the polycarbonate resin film, any one of a casting film forming method and a melt extrusion method can be used. Specific examples of the production method include dissolving a polycarbonate resin in a suitable organic solvent as a polycarbonate resin solution, casting it on a metal support to form a network, and peeling off from the metal support. After the web, the stripped web is dried by hot air to obtain a film.

The acrylic resin to be used for the protective film is not particularly limited, and a copolymer of methacrylate as a main component monomer and a small amount of other comonomer components is generally preferred. The methacrylate which is a main component of the acrylic resin is preferably an alkyl methacrylate, and methyl methacrylate is particularly preferably used. Further, the comonomer component is not particularly limited, and generally, methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate or the like is used. Further, an aromatic vinyl compound such as styrene or an ethylene cyanide compound such as acrylonitrile may also be regarded as Co-monomer component.

The method for producing the acrylic resin can be any conventional method such as bulk polymerization, suspension polymerization, or emulsion polymerization. Among them, in particular, block polymerization in which no water-soluble component is present in the polymerization system is preferred. Further, in order to obtain a suitable glass transition temperature and to obtain a viscosity which exhibits good film formability, it is preferred to use a chain transfer agent during polymerization. The amount of the chain transfer agent may be appropriately determined depending on the type and composition of the monomer. Further, the acrylic resin may contain a conventional additive as needed. The conventional additives may, for example, be a lubricant, an anti-caking agent, a thermal stabilizer, an antioxidant, an antistatic agent, a light stabilizer, an impact modifier, a surfactant, and the like. However, since the protective film laminated on the polarizing film requires transparency, the amount of such additives is preferably minimized.

As a method of producing the acrylic resin film, any one of a melt extrusion method such as a melt casting method, a T-die method, or an inflation method, or a calender method can be used. . Among them, a method in which a raw material resin is melt-extruded from, for example, a T-die, and at least one side of the obtained film is brought into contact with a roll or a belt to form a film is obtained from the viewpoint of obtaining a film having a good surface property. The words are good.

The acrylic resin may contain acrylic rubber particles as an impact modifier, from the viewpoint of film forming properties of the film, impact resistance of the film, and the like. Here, the acrylic rubber particles are not particularly limited as long as they are an elastic polymer having an acrylate as a main component, and are not particularly limited, and a single layer structure composed only of the elastic polymer is substantially exemplified. Or the elastic polymer as a one-layer multilayer structure. Elastic poly Examples of the compound include a crosslinked elastic copolymer obtained by copolymerizing an alkyl acrylate as a main component and another ethylene monomer and a crosslinkable monomer copolymerizable therewith. The alkyl acrylate which is a main component of the elastic polymer may, for example, be an alkyl group such as methyl acrylate, ethyl acrylate, butyl acrylate or 2-ethylhexyl acrylate having a carbon number of from 1 to 8, especially in use. An acrylate having an alkyl group having 4 or more carbon atoms is preferred. Other ethylene monomers copolymerizable with the alkyl acrylate may, for example, be a compound having one polymerizable carbon-carbon double bond in the molecule, and more specifically, a methacrylate such as methyl methacrylate For example, an aromatic vinyl compound such as styrene or an ethylene cyanide compound such as acrylonitrile. Further, the crosslinkable monomer may be a crosslinkable compound having at least two polymerizable carbon-carbon double bonds in the molecule, and more specifically, for example, ethylene glycol di(meth)acrylate and dibutyl A (meth) acrylate of a polyhydric alcohol such as an alcohol di(meth)acrylate, an alkenyl ester of (meth)acrylic acid such as (meth)acrylic acid acrylate, or divinylbenzene.

Further, a laminate of a film made of an acrylic resin not containing rubber particles and a film made of an acrylic resin containing rubber particles may be used as a protective film.

In the polarizing plate used for the viewing side of the liquid crystal display device, the protective film disposed on the side opposite to the liquid crystal cell can be imparted with anti-glare properties. At this time, an anti-glare layer having surface irregularities is generally provided on the surface on the viewing side of the protective film, that is, on the surface opposite to the surface to be adhered to the polarizing material. The antiglare layer is generally formed by imparting irregularities to the active energy ray-curable resin by embossing, or by doping fine particles having refractive indices different from those of the active energy ray-curable resin. Hardened A method of imparting bumps. Further, when the protective film is made of an acrylic resin, it is also effective to form a protective film by using the laminated film described below: a fine resin having a refractive index different from that of the acrylic resin to be a binder is blended. A laminated film of a light diffusion layer and a transparent layer made of an acrylic resin to which the fine particles are not blended. In this case, a laminated film formed by the two layers of the light-diffusing layer and the transparent layer may be attached to the light-diffusing layer side in the form of a polarizing member, or both sides of the light-diffusing layer may be used. The laminated film of the three-layer structure which is sandwiched by the transparent layer is adhered to the form of a polarizer by a transparent layer on one side. Further, when the acrylic resin laminated film which is provided with such a light-diffusing layer and which has an anti-glare property is used as a protective film, the surface on the side of the viewing side, that is, the surface opposite to the surface to be adhered to the polarizing member, By providing the anti-glare layer as described above, it is also possible to more effectively improve the anti-glare property.

As described above, in particular, when an acrylic resin film is used as the protective film, the adhesiveness of the epoxy resin-free epoxy resin disclosed in the prior patent document 6 (JP-A-2004-245925) is not necessarily sufficient. Further, the photocurable adhesive of the present invention can impart a good adhesion even when the acrylic resin film is used as a protective film. Therefore, the present invention is particularly useful when an acrylic resin film is used as a protective film. In this case, it is more preferable that the photocurable adhesive contains an unsaturated compound of the component (D) described above, particularly an acrylic compound.

In the present invention, the protective film formed of a transparent resin film selected from the above-described polyester resin, polycarbonate resin, and acrylic resin is bonded to at least one surface of the polarizer via the photohardening described above. Sexual adhesive And stick. When the protective film is adhered to only one side of the polarizing member, for example, an adhesive layer or the like which is adhered to other members such as liquid crystal cells may be directly provided on the other surface of the polarizing member.

On the other hand, when the protective film is adhered to both surfaces of the polarizer, the respective protective films may be of the same type or different types. Specifically, for example, it is preferable to adopt a form in which a polyester resin film is adhered as a protective film on both sides of the polarizing member, and a polycarbonate resin is used as a protective film on both sides of the polarizing member. a form in which an acrylic resin is adhered to a protective film on both sides of a polarizing member; and one of a polyester resin, a polycarbonate resin, and an acrylic resin is transparent on one side of the polarizing member. The resin film is adhered as a protective film, and a transparent resin film selected from the group consisting of a polyester resin, a polycarbonate resin, and an acrylic resin and different from the one-side protective film is used as the other surface of the polarizing member. The shape of the protective film and the like. Furthermore, it is also possible to adopt a pattern in which a transparent resin film selected from a polyester resin, a polycarbonate resin, and an acrylic resin is applied as a protective film on one side of the polarizing member, and is polarized. On the other side of the article, a transparent resin film which is different from any one of a polyester resin, a polycarbonate resin, and an acrylic resin is used as a protective film. When the protective film is adhered to both sides of the polarizing member, the two protective films may be adhered one by one in a stepwise manner, or both sides may be adhered in one stage.

When the protective film is adhered to both surfaces of the polarizing member, and one of the other resins is made of a polyester resin, a polycarbonate resin, or an acrylic resin, a suitable example of the other resin may be, for example, a cellulose system. tree A fat or amorphous polyolefin resin. Further, a protective film made of a polyester resin, a polycarbonate resin, or an acrylic resin adhered to one surface of the polarizer is adhered to the photocurable adhesive described above according to the present invention, but is polarized. The protective film adhered to the other side of the piece may be followed by another adhesive. For example, when a protective film made of a resin film having a high moisture permeability such as a cellulose resin film is provided on one surface of the polarizing member, a polyvinyl alcohol-based adhesive film may be used for the adhesive film having a high moisture permeability. An adhesive other than an epoxy resin. However, since the photocurable adhesive of the present invention imparts a high adhesion to the cellulose resin film or the amorphous polyolefin resin film exemplified herein, the use of the same adhesive on both sides of the polarizer is simple in operation. It is more advantageous.

A cellulose resin film which can be used as a protective film on one side, and is a partial or complete esterified product of cellulose, and examples thereof include cellulose acetate, propionate, butyrate, and mixed esters thereof. Wait. Specific examples thereof include triethyl fluorenyl cellulose, diethyl acetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate. An example of a commercially available product of a film made of such a cellulose ester-based resin is not particularly limited, and examples thereof include "Fujitac TD80", "Fujitac TD80UF", and "Fujitac TD80UZ" manufactured by Fuji Film Co., Ltd. "KC8UX2M" and "KC8UY" made by Konicaminolta Opto. Further, a cellulose resin film which imparts an optical compensation function can also be used. The optical compensation film is not particularly limited, and examples thereof include a film containing a compound having a phase difference adjustment function in a cellulose resin, and a compound having a phase difference adjustment function applied to a surface of a cellulose resin. A film obtained by stretching a resin into a uniaxial or biaxial direction. Examples of the commercially available cellulose-based optical compensation film are, for example, "Wide view Film WV BZ 438" manufactured by Fuji Film Co., Ltd., and "Wide view Film WV EA", manufactured by Konicaminolta Opto Co., Ltd. "KC4FR-1" and "KC4HR-1", etc.

The transparent resin having a low moisture permeability, which is used as a protective film for one side, which is different from the polyester resin, the polycarbonate resin, and the acrylic resin, is not particularly limited, and examples thereof include amorphous polyolefin resins. , polyfluorene resin, alicyclic polyimide resin, and the like. Among them, the film made of the amorphous polyolefin resin is a film excellent in mechanical properties, solvent resistance, scratch resistance, cost, and the like, and is particularly suitable for use.

The amorphous polyolefin-based resin generally has a polymerized unit derived from a polycyclic cyclic olefin such as norbornene or a derivative thereof, or a dicyclic octahydronaphthalene, and remains as a ring-like polymer. When the bond is used, it is preferred to hydrogenate the thermoplastic resin. The amorphous polyolefin-based resin may be a copolymer of a cyclic olefin and a chain olefin, or may be a polar group. Among them, a thermoplastic resin saturated norbornene-based resin is exemplified as a representative example. Examples of the commercially available amorphous polyolefin-based resin include "ARTON" of JSR (share), "ZEONEX" by Japan Zeon Co., and "ZEONOR", and "APO" by Mitsui Chemicals Co., Ltd. And "APPEL" and so on. When a film is formed by forming a film of the amorphous polyolefin resin, a conventional method such as a solvent molding method or a melt extrusion method can be suitably used for the film formation.

The protective film may be subjected to a saponification treatment, a corona treatment, a primer treatment, an anchor coating treatment, or the like, before being adhered to the polarizing member. Also, pasting the polarizing member on the protective film The surface on the opposite side of the surface may have various treatment layers such as a hard coat layer, an antireflection layer, and an antiglare layer. The thickness of the protective film is not particularly limited and is usually in the range of about 5 to 200 μm, preferably 10 to 120 μm, more preferably 10 to 85 μm.

[Method of Manufacturing Polarizing Plate]

The polarizing plate of the present invention can be produced by a method comprising the steps of: bonding a polarizing member previously described and a protective film made of a transparent resin film selected from the group consisting of polyester resin, polycarbonate resin and acrylic resin. At least one side of the surface, an adhesive application step of applying a photocurable adhesive as described above; a bonding step of adhering the polarizer to the protective film via the obtained adhesive layer; and a polarizing having been adhered to the adhesive layer A hardening step of hardening the photocurable adhesive in the state of the member and the protective film.

<Binder coating step>

The subsequent coating step is to apply the photocurable adhesive described above to at least one of the adhesive faces of the polarizer and the protective film. When the photocurable adhesive is directly applied to the surface of the polarizer or the protective film, the coating method is not particularly limited. For example, various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Further, a method in which the photocurable adhesive described above is cast between the polarizer and the protective film, and then pressurized by a roller or the like to uniformly expand and expand may be used.

<Paste step>

After the photocurable adhesive is applied as described above, it is supplied to the pasting step. In the pasting step, for example, in the previous coating step on the surface of the polarizer When the photocurable adhesive is applied to the surface, the protective film is laminated there, and when the photocurable adhesive is applied to the surface of the protective film in the previous coating step, the polarizer is laminated there. Further, when the photocurable adhesive is delayed between the polarizer and the protective film, the polarizer and the protective film are laminated in this state. When the protective film is adhered to both surfaces of the polarizer and the photocurable adhesive of the present invention is used on both surfaces, the protective film is laminated on both surfaces of the polarizer via a photocurable adhesive. Therefore, it is usually in this state from both sides (when the protective film is superposed on one side of the polarizing member, the polarizer side and the protective film side are overlapped, and when the protective film is laminated on both sides of the polarizing member, the two sides thereof are The protective film side) is caught by a roller or the like and pressurized. Here, the material of the roller can be metal or rubber. The rollers arranged on both sides can be of the same material or different materials.

<hardening step>

As described above, the state in which the polarizer and the protective film are adhered via the uncured photocurable adhesive is followed by the hardening step. In the hardening step, the photocurable adhesive is applied to the active energy source to cure the adhesive layer containing the epoxy compound or the oxetane compound, and the polarizer and the protective film are followed. When the protective film is adhered to one side of the polarizing member, the active energy source can be irradiated from either the polarizer side or the protective film side. Further, when the protective film is adhered to both surfaces of the polarizer, the active light rays are irradiated from the side of the protective film on either side of the polarizer with the photocurable adhesive adhered to the protective film, and the light of both sides is hardened. It is advantageous for the adhesive to harden at the same time. However, when a UV absorber is blended in the protective film on either side (for example, a cellulose resin film blended with a UV absorber is used as a side protection) When the protective film is ultraviolet light, it is usually irradiated with ultraviolet rays from the side of the protective film which is not doped with the ultraviolet absorber.

Although the visible light rays, ultraviolet rays, X-rays, electron beams, and the like can be used as the active energy source, it is generally preferable to use ultraviolet rays from the viewpoint of easy handling and fast curing speed. The light source of the active energy source is not particularly limited, and for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high pressure mercury lamp, a chemical lamp, a black light lamp, a microwave-excited mercury lamp having a light-emitting distribution at a wavelength of 400 nm or less can be used. Metal halide lamps, LED lamps, etc.

The light irradiation intensity of the photocurable adhesive is determined depending on each of the intended compositions, and is not particularly limited, but the irradiation intensity in the effective wavelength region in which the polymerization initiator is activated is UV-B (280 to It is preferably from 1 to 3,000 mW/cm ^{2 in} terms of ultraviolet light in the wavelength region of 320 nm. When the irradiation intensity is less than 1 mW/cm ² , the reaction time becomes too long. On the other hand, when the irradiation intensity exceeds 3,000 mW/cm ² , the heat emitted by the lamp and the polymerization of the photocurable adhesive are caused. It is heated, and there is a possibility that yellowing of the photocurable adhesive or deterioration of the polarizer occurs.

The light irradiation time of the photocurable adhesive is controlled by each hardened composition, and is not particularly limited, but is set so that the integrated light amount expressed by the product of the irradiation intensity and the irradiation time is 10 to 5,000 mJ/cm ^{2 .} It is better. When the total amount of light is 10 mJ/cm ² or less, the generation of the active species derived from the polymerization initiator is insufficient, and the curing of the binder may become insufficient. On the other hand, when the cumulative amount of light exceeds 5,000 mJ/cm ² , The irradiation time becomes very long, which is not conducive to the improvement of productivity.

When the photocurable adhesive is cured by irradiation of the active energy source, it is preferable to harden the polarizing plate such as the polarizing degree, the transmittance, the hue, and the permeability of the protective film. .

In the polarizing plate thus obtained, the thickness of the adhesive layer is not particularly limited, but is usually 50 μm or less, preferably 20 μm or less, and more preferably 10 μm or less.

[Optical member]

When a polarizing plate is used, an optical member which is formed on one side of the optical layer and which exhibits an optical function other than the optical function of the polarizing function can be formed. The optical layer laminated on the polarizing plate for the purpose of forming an optical member is not particularly limited, and examples thereof include a reflective layer, a semi-transmissive reflective layer, a light diffusion layer, a phase difference plate, a light collecting plate, and a film for improving brightness. Various optical layers used in forming a liquid crystal display device or the like. The reflective layer, the semi-transmissive reflective layer, and the light-diffusing layer are used for forming an optical member made of a polarizing plate of a reflective type or a transflective type or a diffused type.

The reflective polarizing plate is used in a liquid crystal display device of a type that reflects incident light from the viewing side. Since a light source such as a backlight can be omitted, the liquid crystal display device can be easily made thinner. Further, the semi-transmissive polarizing plate is used in a liquid crystal display device of a type that is displayed in a bright place as a reflective display and in a dark place using a light source such as a backlight. As an optical member of the reflective polarizing plate, for example, a foil made of a metal such as aluminum or a vapor deposited film may be attached to the protective film on the polarizer to form a reflective layer. As the optical member of the semi-transmissive polarizing plate, the reflective layer can be used as a half mirror or a reflective sheet containing pearl pigment or the like and exhibiting light transmittance. It is then formed on a polarizing plate. On the other hand, as the optical member of the diffusing type polarizing plate, for example, a method of performing a matting treatment on a protective film on a polarizing plate, a method of applying a resin containing fine particles, and a method of forming a film containing fine particles are used. On the surface, a fine uneven structure is formed.

Further, the formation of the optical member as the polarizing plate for reflection and diffusion can be performed, for example, by providing a reflecting layer or the like reflecting the uneven structure on the fine uneven structure surface of the diffusing type polarizing plate. The reflective layer of the fine uneven structure diffuses incident light by random reflection, and has the advantages of preventing directivity or glare, suppressing unevenness of light and dark, and the like. Further, the resin layer or the film containing the fine particles diffuses the incident light and the reflected light thereof while passing through the layer containing the fine particles, and has an advantage of further suppressing unevenness in brightness and the like. The reflective layer reflecting the fine uneven structure on the surface can be formed by directly attaching a metal to the surface of the fine uneven structure by vapor deposition or plating such as vacuum deposition, ion plating or sputtering. The fine particles blended to form the fine uneven structure on the surface can be formed, for example, from cerium oxide, aluminum oxide, titanium oxide, zirconium oxide, tin oxide, indium oxide, cadmium oxide, or cerium oxide having an average particle diameter of 0.1 to 30 μm. Inorganic fine particles, organic fine particles formed by crosslinking or terminally crosslinked polymers, and the like.

On the other hand, the phase difference plate as the optical layer is used for the purpose of compensating for the phase difference caused by the liquid crystal cell. Is not particularly limited and examples thereof include such as: by an extension of the other plastic film to the birefringent film with a discotic liquid crystal to fix the alignment (discotic liquid crystal) film or nematic liquid crystal (nematic liquid crystal), the The liquid crystal layer or the like is formed on the film substrate. In this case, the film substrate supporting the alignment liquid crystal layer is not particularly limited, and a cellulose film such as triethylenesulfonyl cellulose is preferably used.

The plastic forming the birefringent film is not particularly limited, and examples thereof include polyolefins such as polycarbonate, polyvinyl alcohol, polystyrene, polymethyl methacrylate, and polypropylene, polyarylate, and poly Amidoxime, an amorphous polyolefin resin, or the like. The stretch film can be handled by a suitable method such as uniaxial or biaxial. Further, a birefringent film which controls the refractive index in the thickness direction of the film by applying a shrinking force and/or an extending force to the heat-shrinkable film may be used. Further, for the purpose of controlling optical characteristics such as wide banding, the phase difference plate may be used in combination of two or more.

The light collecting plate is a user for controlling the optical path or the like, and can be formed as a tantalum array sheet, a lens array sheet, or a sheet of attachment dots.

The film for improving the brightness is used for the purpose of improving the brightness in a liquid crystal display device or the like. For example, a film in which the refractive indices of the plurality of refractive indexes are different from each other is laminated to cause anisotropy of the reflectance. A reflective linear polarizing separation sheet designed in a sexual manner, a alignment film of a cholesteric liquid crystal polymer or a circularly polarizing separation sheet supporting the liquid crystal layer on a film substrate.

In the optical member, one or two or more layers of the polarizing plate and the semi-transmissive reflective layer, the light-diffusing layer, the retardation plate, the light-concentrating plate, and the film for improving brightness can be selected for the purpose of use. The optical layers are combined to form a laminate of two or more layers. At this time, the optical layer such as the light diffusion layer or the phase difference plate, the light collecting plate, or the film for improving brightness may also be respectively Configure more than 2 layers. Meanwhile, the arrangement of the optical layers is not particularly limited.

Since the various optical layers forming the optical member are integrated with the polarizing plate using an adhesive, the adhesive to be used may be any one as long as it can form the adhesive layer well, and is not particularly limited. It is preferable to use an adhesive (also referred to as a pressure-sensitive adhesive) from the viewpoint of ease of handling, prevention of occurrence of optical deformation, and the like. As the adhesive, an acrylic polymer, a silicone polymer, a polyester, a polyurethane, a polyether or the like can be used as a base polymer. Among them, the use of an acrylic adhesive is excellent in optical transparency, maintains moderate wettability or cohesive force, and is excellent in adhesion to a substrate, and has weather resistance, heat resistance, etc., under heating or humidification conditions. It is preferable that there is no peeling problem such as floating or peeling. In the acrylic adhesive, the following acrylic copolymer can be used as a useful base polymer: an alkyl (meth)acrylate having an alkyl group having a carbon number of 20 or less, such as a methyl group, an ethyl group or a butyl group. The acrylic monomer containing a functional group derived from (meth)acrylic acid or hydroxyethyl (meth)acrylate may preferably have a glass transition temperature of 25 ° C or less, more preferably 0 ° C or less. While blending and polymerizing, an acrylic copolymer having a weight average molecular weight of 100,000 or more is obtained.

The formation of the adhesive layer on the polarizing plate can be carried out by, for example, dissolving or dispersing the adhesive composition in an organic solvent such as toluene or ethyl acetate to prepare a solid concentration of 10 to 40% by weight. A liquid, which is applied directly to a polarizing plate to form an adhesive layer, or a method in which an adhesive layer is formed on a separation film in advance, and then moved to a polarizing plate to form an adhesive layer. The thickness of the adhesive layer is in response to its adhesion It is decided to be in the range of about 1 to 50 μm.

Further, in the adhesive, a filler, a pigment or a colorant, an antioxidant, an ultraviolet absorber, which is formed of glass fiber or glass pellet, resin pellet, metal powder or other inorganic powder may be blended according to requirements. Wait. The ultraviolet absorber is not particularly limited, and examples thereof include a salicylate-based compound, a benzophenone-based compound, a benzotriazole-based compound, a cyanoacrylate-based compound, and a nickel-salted salt-based compound.

[Liquid Crystal Display Device]

The above optical member can be disposed on one side or both sides of the liquid crystal cell to form a liquid crystal display device. The liquid crystal cell to be used may be any one. For example, a liquid crystal display device may be formed by using various liquid crystal cells such as an active matrix drive type represented by a thin film transistor type and a simple matrix drive type represented by a super twisted nematic type. The optical members disposed on both sides of the liquid crystal cell may be the same or different.

[Examples]

Hereinafter, the present invention will be more specifically described by way of examples and comparative examples. However, the present invention is not limited to the examples, and the examples show that the amount of use or the content is based on the weight unless otherwise specified.

In the examples and comparative examples, the components used for the preparation of the adhesive composition are as follows, and are hereinafter referred to as individual symbols (the product name itself or a part thereof).

(A) component: epoxy compound

jER-828: bisphenol A type epoxy resin, "jER-828" made by Japan Epoxy Resins Co., Ltd.

jER-152: Phenolic novolac type epoxy resin, "jER-152" manufactured by Japan Epoxy Resins Co., Ltd.

ECC: 3,4-epoxycyclohexylmethyl 3,4-epoxycyclohexanecarboxylic acid.

(B) Component: Oxetane compound

OXT-211: 3-ethyl-3-phenoxymethyloxetane, "Aronoxetane OXT-211" manufactured by East Asia Synthetic Co., Ltd.

OXT-221: 3-ethyl-3-[(3-ethyloxetan-3-yl)methoxymethyl]oxetane, manufactured by East Asia Synthetic Co., Ltd. "Aronoxetane OXT- 221".

OXT-121: Difunctional with 1,4-bis[(3-ethyloxetan-3-yl)methoxymethyl]benzene as the main component of xylylene backbone Oxetane compound, "Aronoxetane OXT-121" made by East Asia Synthetic Co., Ltd.

The structures of these oxetane compounds are shown below.

(C) component: photocationic polymerization initiator

UVI-6992: a 50% propylene carbonate solution containing a triarylsulfonium hexafluorophosphate as a main component, "UVI-6992" manufactured by The Dow Chemical Company.

(D) Component: Acrylic unsaturated compound

M-203S: Tricyclodecane Dihydroxymethyl Diacrylate, "Aronix M-203S" made by East Asia Synthetic Co., Ltd.

(E) component: photoradical polymerization initiator

Irg 184: 1-hydroxycyclohexyl phenyl ketone, "Irgacure 184" manufactured by Ciba.

(F) component: other components without polymerization

BR-60: a methyl methacrylate copolymer, "Dianal BR-60" manufactured by Mitsubishi Rayon Co., Ltd.

[Preparation of the composition of the adhesive]

The components shown in Tables 1 and 2 were blended at their respective ratios, and stirred and mixed in accordance with a usual method to prepare a photocurable adhesive composition. Further, since "UVI-6992" used as the component (C) is a propylene carbonate solution containing 50% of an active ingredient, in the table, the component (C) is shown separately from the propylene carbonate. That is, the blending amount of " UVI-6992 " in the table refers to the ratio of the solid fraction, and the blending amount of "UVI-6992" itself is the amount shown in the column (C) and the propionate column. The amounts shown are combined to be 6%.

[Production of polarizing plate (1)]

Here, the following two types of films are used for the protective film.

The norbornene-based resin film was stretched to a thickness of 70 μm, and the product name was "ZEONOR film" manufactured by Zeon Co., Ltd., Japan. After the film is subjected to a corona discharge treatment, it is supplied to be combined with a polarizing member.

Biaxially stretched polyethylene terephthalate film: 50 μm thick, trade name "E5001", manufactured by Toyobo Co., Ltd. Performing a corona discharge on the film After the electrical treatment, it is combined with the polarizer.

On the corona discharge treated surface of the above-mentioned extended norbornene-based resin film, the above-mentioned prepared adhesive composition was applied to a thickness of 3 μm by a bar coater, and a polarizer obtained by adsorbing and absorbing iodine from polyvinyl alcohol was adhered thereto. Further, in the above biaxially-oriented polyethylene terephthalate film, the same adhesive was applied to a thickness of 3 μm by a bar coater, and the norbornene adhered to the polarizer of the norbornene-based resin film was adhered. On the opposite side of the resin film. For the polarizer to which the protective film is adhered on both sides, the ultraviolet light irradiation device (the "Fusion H lamp" manufactured by Fusion Co., Ltd.) equipped with a belt conveyor is used, and the cumulative light amount is 300 mJ from the surface of one side. /cm ^{2 was} irradiated with ultraviolet rays, left at room temperature for 1 hour, and a protective film made of a polyethylene terephthalate film was adhered to one side, and an extended norbornene-based resin film was adhered on the other side. Polarizer (1).

[Production of polarizing plate (2)]

The biaxially stretched polyethylene terephthalate film was changed to an acrylic resin film [thickness 80 μm, trade name "Technoloy S001", manufactured by Sumitomo Chemical Co., Ltd.], and the others were operated in the same manner as the polarizing plate (1). A protective film made of an acrylic resin film was adhered to one side, and a polarizing plate (2) having an extended norbornene-based resin film adhered to the other surface was formed.

[evaluation test]

The obtained polarizing plates were evaluated for hardenability, adhesion, and durability by the following methods, and the results are shown in Tables 1 and 2.

<hardenability>

Try to peel off the polarizer and polyethylene terephthalate film by hand or When the acrylic resin film is completely cured and cannot be peeled off, or if it is peeled off, the tack is not left in the portion (adhesiveness due to the adhesive is not cured), and it is evaluated as "○". Those who peel off and have residual stickiness in this part are evaluated as "X".

<adhesion>

When the cutting blade is inserted obliquely from the polyethylene terephthalate film or the acrylic resin film, the film is peeled off from the polarizing member and the blade is cut into the polyethylene terephthalate film or The difference between the acrylic resin film and the polarizer was evaluated as the worst "X". When there was no peeling in this test, the following evaluation was further carried out. That is, the polarizing plate is cut into a rectangular shape having a width of 1 cm in the extending direction as a long side, and is used in a direction perpendicular to the extending direction from the surface of the polyethylene terephthalate film or the acrylic resin film. When the cutter was cut shallowly, and the cut-out portion was taken as the outer side and bent into a "ㄑ" shape, the degree of peeling of the end portion was observed. Here, when the end portion was peeled off, peeling was attempted by hand from the peeling portion, and it was evaluated whether or not peeling occurred and the film was material failure. The following judgments are made based on the results of the evaluation.

△: The peeling of the end portion at the time of bending is large, and it is easy to peel off by hand.

○: The end portion was peeled off by about 1 mm when bent, and when the peeling was attempted by hand, the film was broken.

◎: When the bending is hardly peeled off, and the peeling is performed by hand, the film may be broken.

<Durability>

For good samples with an adhesion above "○", they will be placed at -35 °C. The thermal shock cycle test of 60 minutes and then placed at +70 ° C for 60 minutes and repeated 300 cycles, with a sample size of 2 types of diagonal 15 inches (about 38 cm) and diagonal 5 inches (about 13 cm) To implement, and make the following assessment.

○: There is no defect in the appearance of 15 inches.

△: There is a partial appearance defect at 15 inches, but there is no defect in the appearance of 5 inches.

X: Even in the appearance of 5 inches, it is not good.

As shown in Table 1, the polarizing plate-based polarizers of Examples 1 to 7 produced by using the photocurable adhesive composition of the present invention have good adhesion to the protective film and good curability. In the examples 1 to 3 in which the oxetane compound of the component (B) is "OXT-211" having one oxetanyl group and one aromatic ring in the molecule, the adhesion is particularly good. . Contains 18% of the acrylic unsaturated compound "M-203S" with an alicyclic backbone In Example 3 as the component (D), durability was good in addition to good adhesion. Further, in Examples 4 to 7 in which the oxetane compound "OXT-221" having two oxetanyl groups in the molecule and having a liquid molecular weight of 500 or less at room temperature was used (Example 4 is Used in combination with "OXT-121"), the balance between adhesion and durability is excellent. Among them, Examples 4 and 5 containing 18% of the acrylic unsaturated compound "M-203S" were particularly excellent in adhesion.

On the other hand, as shown in Table 2, Comparative Examples 1 and 2 which do not contain the (B) component oxetane compound lacked the adhesiveness. In particular, in Comparative Example 2 in which the acrylic unsaturated compound of the component (D) was blended to 43%, the polyethylene terephthalate film and the acrylic resin film were inferior in adhesion. Further, Comparative Example 3, which does not contain the epoxy compound of the component (A), was inferior in both curability and adhesion.

[Industrial availability]

The photocurable adhesive composition of the present invention is easily cured by irradiation with an active energy source such as ultraviolet rays, and the polarizer and the protective film are firmly adhered in a short time, so that the usability is available.

Claims (20)

A photocurable adhesive composition which is formed on a polarizing member made of a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed to a dichroic dye, and is then used to be selected from a polyester resin and a poly An adhesive composition of a protective film formed of a transparent resin film of a group of a carbonate resin and an acrylic resin; characterized by comprising: (A) an epoxy compound having at least two epoxy groups in the molecule, ( B) an oxetane compound having at least one oxetanyl group in the molecule, (C) a photocationic polymerization initiator, and (F) a methyl methacrylate having a glass transition temperature of 70 ° C or higher a polymer; the weight ratio (A)/(B) of the epoxy compound (A) to the oxetane compound (B) is 90/10 to 10/90, and the photocationic polymerization initiator (C) The amount is from 0.5 to 20% by weight in the composition. The photocurable adhesive composition according to claim 1, wherein the epoxy compound (A) comprises a compound having at least two epoxy groups and at least one aromatic ring in the molecule. The photocurable adhesive composition according to claim 2, wherein the epoxy compound (A) is selected from the group consisting of glycidyl ethers and glycidyl esters of aromatic compounds. For example, the photocurable adhesive composition of claim 1 or 2, Among them, the oxetane compound (B) contains a compound having at least one oxetanyl group and at least one aromatic ring in the molecule. The photocurable adhesive composition according to claim 1 or 2, wherein the oxetane compound (B) comprises a compound having two oxetanyl groups in the molecule. The photocurable adhesive composition according to claim 1, wherein the epoxy compound (A) is a compound having at least two epoxy groups and at least one aromatic ring in the molecule, or has a molecule A mixture of at least two compounds having an epoxy group and at least one aromatic ring and a compound having at least two epoxy groups in the molecule but no aromatic ring. The photocurable adhesive composition of the sixth aspect of the invention, wherein the epoxy compound (A) is one or more selected from the group consisting of glycidyl ethers and glycidyl esters of aromatic compounds, or A mixture of one or more of the epoxy compound (A) other than the group of the glycidyl ether compound and the glycidyl ester compound of the aromatic compound is selected. The photocurable adhesive composition according to claim 1 or 6, wherein the oxetane compound (B) has one oxetanyl group and at least one aromatic ring in the molecule. A compound, or a mixture of a compound having one oxetanyl group and at least one aromatic ring in the molecule, and a compound having at least one oxetanyl group in the molecule but no aromatic ring. The photocurable adhesive composition according to claim 1 or 6, wherein the oxetane compound (B) is a compound having at least two oxetanyl groups in the molecule, or At least 2 in the molecule A mixture of a compound of oxetanyl and a compound having one oxetanyl group in the molecule. The photocurable adhesive composition according to the first, second or sixth aspect of the invention, wherein the composition has a ratio of 35% by weight or less in the composition (D) having at least one ethylenically unsaturated bond in the molecule. Unsaturated compound. The photocurable adhesive composition of claim 10, wherein the unsaturated compound (D) is contained in the composition in a ratio of 5 to 25% by weight. The photocurable adhesive composition of claim 10, wherein the unsaturated compound (D) has at least one (meth) acrylonitrile group and at least one alicyclic backbone or aromatic ring in the molecule. A (meth)acrylic compound of the backbone. The photocurable adhesive composition according to claim 12, wherein the unsaturated compound (D) is a di(meth)acrylate having a tricyclodecane backbone. The photocurable adhesive composition according to claim 10, wherein the (E) photoradical polymerization initiator is further contained in the composition at a ratio of 10% by weight or less. The photocurable adhesive composition according to the first aspect of the invention, wherein the amount of the methyl methacrylate-based polymer (F) is 10% by weight or less. A polarizing plate which is formed on a polarizing member made of a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed to a dichroic dye, and is interposed a polarizing plate formed by a protective film made of a transparent resin film selected from the group consisting of a polyester resin, a polycarbonate resin, and an acrylic resin; characterized in that the adhesive is in the scope of the patent application The one formed by the photocurable adhesive composition of item 1. A method for producing a polarizing plate, which is obtained by a polyvinyl alcohol-based resin film which is uniaxially stretched and adsorbed to a dichroic dye, and is adhered to a polyester resin by an adhesive. a method of producing a polarizing plate by forming a protective film of a transparent resin film of a group of a polycarbonate resin and an acrylic resin; characterized by comprising the following steps: an adhesive coating step: the polarizing member and the protective film Applying the photocurable adhesive composition of claim 1 on at least one side of the adhesive surface; pasting step: adhering the polarizing member and the protective film through the obtained adhesive layer; and hardening step: separating The photocurable adhesive composition is cured in a state in which the polarizer and the protective film are adhered while the adhesive layer is adhered. An optical member characterized in that another optical layer is laminated on a polarizing plate of claim 16 of the patent application. An optical member according to claim 18, wherein the other optical layer comprises a phase difference plate. A liquid crystal display device characterized in that an optical member of claim 18 or 19 is disposed on one side or both sides of a liquid crystal cell.