JP6394011B2 - Manufacturing method of polarizing plate - Google Patents

Description

  In the present invention, polarized light in which a polarizing film made of a polyvinyl alcohol resin and a protective film made of a thermoplastic resin are bonded via an adhesive made of a curable composition containing an active energy ray-curable compound. The present invention relates to a method for manufacturing a plate.

  The polarizing plate is useful as one of the optical components constituting the liquid crystal display device. A polarizing plate usually has a structure in which protective films are laminated on both sides of a polarizing film, and is incorporated in a liquid crystal display device. It is also known to provide a protective film only on one side of the polarizing film, but in many cases the other side is not just a protective film, but a film having another optical function also serves as the protective film. Pasted together.

  As a method for producing a polarizing film, a method in which a uniaxially stretched polyvinyl alcohol-based resin film dyed with a dichroic dye is treated with boric acid, washed with water, and dried is widely adopted. Since the polarizing film obtained in this way has problems such as low physical strength and easy tearing in the processing direction, as described above, a protective film is bonded to at least one side, usually both sides, via an adhesive. The As an adhesive for this purpose, a water-based adhesive made of an aqueous solution of a polyvinyl alcohol resin has been traditionally used. Traditionally, a triacetyl cellulose film having a thickness of 30 to 100 μm has been used as a protective film.

  Triacetyl cellulose is excellent in transparency, easy to form various surface treatment layers and optical functional layers, has high moisture permeability, and can be dried after being bonded to a polarizing film using an aqueous adhesive as described above. Since it has an excellent advantage as a protective film, it can be performed smoothly, it is still widely used today. On the other hand, the polarizing plate to which the protective film made of triacetyl cellulose is bonded due to the high moisture permeability tends to cause deterioration under wet heat, for example, at a temperature of 70 ° C. and a relative humidity of 90%. There were problems such as. Therefore, for applications in which such problems are likely to be manifested, as a protective film, for example, an amorphous polyolefin resin (also referred to as a cycloolefin resin) whose moisture permeability is smaller than that of triacetyl cellulose, for example, norbornene resin is a representative example. Pasting is also widely performed in recent years.

  When bonding a protective film made of a resin with low moisture permeability to a polyvinyl alcohol polarizing film, an aqueous solution of a polyvinyl alcohol resin that has been conventionally used for bonding a polyvinyl alcohol polarizing film and a triacetyl cellulose film is used. When the adhesive is used, there are problems that the adhesive strength is not sufficient or the appearance of the obtained polarizing plate becomes poor. This is because a resin film having a low moisture permeability is generally hydrophobic, and water as a solvent cannot be sufficiently dried due to a low moisture permeability. On the other hand, it is also known to bond different types of protective films on both sides of the polarizing film. For example, a protective film made of a resin with low moisture permeability such as an amorphous polyolefin resin is bonded to one surface of the polarizing film, and a cellulose resin such as triacetyl cellulose is bonded to the other surface of the polarizing film. There is a proposal to bond a protective film made of a resin having a high moisture permeability.

  Then, while giving a high adhesive force between the protective film made of a resin having a low moisture permeability and the polyvinyl alcohol polarizing film, the protective film made of a resin having a high moisture permeability such as a cellulose resin and the polyvinyl alcohol polarizing film There is an attempt to use a photo-curable adhesive as an adhesive that gives a high adhesive strength even between them. For example, Japanese Patent No. 4306270 (Patent Document 1) discloses an adhesive mainly composed of an epoxy compound that does not contain an aromatic ring, and is a cation produced by irradiation with active energy rays, specifically ultraviolet irradiation. It has been proposed to cure the adhesive by polymerization and bond the polarizing film and the protective film. JP-A-2008-257199 (Patent Document 2) discloses a photocurable adhesive comprising a combination of an alicyclic epoxy compound and an epoxy compound having no alicyclic epoxy group, and further containing a photocationic polymerization initiator. The technique which uses an agent for adhesion | attachment with a polarizing film and a protective film is disclosed.

  There are also various attempts to increase the durability of the polarizing plate. For example, JP 2009-282137 A (Patent Document 3) describes a polyvinyl alcohol polarizing film using an active energy ray-curable adhesive. When adhering to the protective film, the polarizing film is subjected to an immersion treatment with an aqueous iodide solution having a pH of 7.5 to 9.5 after the stretching treatment, thereby suppressing polyene formation upon irradiation with active energy rays. It is disclosed that the durability of the obtained polarizing plate is improved. According to this method, although the durability of the polarizing plate can be improved, the polarizing film after being treated with an iodide aqueous solution and dried may have a poor appearance.

Japanese Patent No. 4306270 (Japanese Patent Laid-Open No. 2004-245925) JP 2008-257199 A JP 2009-282137 A

  A known photo-curable adhesive bonds a polarizing film and a protective film with an appropriate adhesive force, but the adhesive force is not necessarily sufficient. For example, the photo-curable adhesive is used to protect the polarizing film and the protective film. A polarizing plate obtained by laminating a film is applied to a liquid crystal display device, and when the edge is polished in a state of being cut into a predetermined size, the protective film may be peeled off from the polarizing film at the edge. there were.

  The object of the present invention is from a thermoplastic resin via an adhesive made of a curable composition containing an active energy ray-curable compound to a polarizing film made of a polyvinyl alcohol-based resin in which a dichroic dye is adsorbed and oriented. In the polarizing plate on which the protective film to be bonded is bonded, the adhesive force between the polarizing film and the protective film made of a thermoplastic resin is increased.

  As a result of research, at least one side of a polarizing film made of a polyvinyl alcohol-based resin on which dichroic dye is adsorbed and oriented is thermoplastic via an adhesive made of a curable composition containing an active energy ray-curable compound. When a protective film made of resin is bonded and a polarizing plate is produced, the polarizing film is pre-immersed in water, and then bonded to the protective film via the adhesive, whereby the polarizing film and the protective film It has been found that the adhesive strength increases.

  That is, according to the present invention, a polarizing film is produced by bonding a protective film made of a thermoplastic resin via an adhesive to a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin. The adhesive is made of a curable composition containing an active energy ray curable compound, and the polarizing film after the immersion process, the immersion process of immersing the polarizing film in water, Provided is a method for producing a polarizing plate comprising a laminating step of laminating the protective film via an adhesive, and a curing step of irradiating the active body with an active energy ray to cure the adhesive. Is done.

  In this method, it is preferable that the said immersion process is performed by immersing said polarizing film in water for 1 minute or more. Moreover, it is preferable to provide the water removal process which removes the water | moisture content adhering to the surface of the polarizing film at the immersion process between said immersion process and said lamination process.

  According to the production method of the present invention, an adhesive made of a curable composition containing an active energy ray-curable compound is provided on at least one surface of a polarizing film made of a polyvinyl alcohol-based resin on which a dichroic dye is adsorbed and oriented. In a polarizing plate to which a protective film made of a thermoplastic resin is bonded, the polarizing film and the thermoplastic resin are protected by immersing the polarizing film in water before the polarizing film is bonded to the protective film. A polarizing plate having an increased adhesion to the film can be advantageously produced.

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

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings as appropriate. As shown in FIG. 1, the polarizing plate to be produced in the present invention is obtained by bonding a protective film 2 made of a thermoplastic resin to a polarizing film 1 in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin. It is a thing. And the adhesive bond layer 4 which consists of hardened | cured material of the curable composition containing an active energy ray hardening compound interposes in both interface. The protective film 2 made of a thermoplastic resin may be bonded to at least one surface of the polarizing film 1, and of course, the protective film may be bonded to both surfaces of the polarizing film 1.

  In the case where a protective film made of a thermoplastic resin is bonded to both surfaces of the polarizing film, as shown in FIG. 2, the surface of the polarizing film 1 opposite to the surface on which one protective film 2 is bonded is thermoplastic. Another protective film 3 made of resin is bonded. Also in that case, it is preferable that another adhesive layer 5 made of a cured product of the curable composition containing the active energy ray-curable compound is interposed at the interface between the polarizing film 1 and the protective film 3. As shown in FIG. 2, when bonding the protective films 2 and 3 which consist of thermoplastic resins on both surfaces of the polarizing film 1, the two protective films 2 and 3 may be the same or different, The adhesive layers 4 and 5 may be formed from the same adhesive or different adhesives.

  First, each component of the polarizing plate will be described.

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

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

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

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

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

  The polyvinyl alcohol resin film is dyed with a dichroic dye, for example, by immersing the polyvinyl alcohol resin film in an aqueous solution containing the dichroic dye. As the dichroic dye, for example, iodine or a dichroic organic dye is used. Examples of the dichroic organic dye include dichroic direct dyes composed of disazo compounds such as C.I. DIRECT RED 39, and dichroic direct dyes composed of compounds such as trisazo and tetrakisazo. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

  When iodine is used as the dichroic dye, a method of dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed. The content of iodine in this aqueous solution is usually 0.01 to 1 part by weight per 100 parts by weight of water, and the content of potassium iodide is usually 0.5 to 20 parts by weight per 100 parts by weight of water. . When iodine is used as the dichroic dye, the temperature of the aqueous solution used for dyeing is usually 20 to 40 ° C., and the immersion time (dyeing time) in this aqueous solution is usually 20 to 1,800 seconds. .

On the other hand, when a dichroic organic dye is used as the dichroic dye, a method of immersing and dyeing a polyvinyl alcohol-based resin film in an aqueous solution containing a water-soluble dichroic organic dye is usually employed. The content of the dichroic organic dye in this aqueous solution is usually 1 × 10 ⁻⁴ to 10 parts by weight, preferably 1 × 10 ⁻³ to 1 part by weight, more preferably 1 × 10 10 per 100 parts by weight of water. ⁻³ to 1 × 10 ⁻² parts by weight. This aqueous solution may contain an inorganic salt such as sodium sulfate as a dyeing assistant. When a dichroic organic dye is used as the dichroic dye, the temperature of the aqueous dye solution used for dyeing is usually 20 to 80 ° C., and the immersion time (dyeing time) in this aqueous solution is usually 10 to 1. 800 seconds.

  The boric acid treatment step is performed by immersing a polyvinyl alcohol-based resin film dyed with a dichroic dye in a boric acid-containing aqueous solution. The amount of boric acid in the boric acid-containing aqueous solution is usually 2 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water. When iodine is used as the dichroic dye in the dyeing process described above, the aqueous solution used in the boric acid treatment process preferably contains potassium iodide in addition to boric acid. In this case, the content of potassium iodide in the boric acid-containing aqueous solution is usually 0.1 to 15 parts by weight, preferably 5 to 12 parts by weight per 100 parts by weight of water. The immersion time in the boric acid-containing aqueous solution is usually 60 to 1,200 seconds, preferably 150 to 600 seconds, and more preferably 200 to 400 seconds. The temperature of the boric acid-containing aqueous solution is usually 50 ° C. or higher, preferably 50 to 85 ° C., more preferably 60 to 80 ° C.

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

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

  The adhesive layer 4 made of a cured product of a curable composition containing an active energy ray-curable compound for attaching the polarizing film 1 and the protective film 2 made of a thermoplastic resin is described in detail below. It is formed using an adhesive. When adhering these films using an adhesive, plasma treatment, corona treatment, ultraviolet irradiation treatment, flame (flame) treatment, kenning are performed on the protective film 2 made of thermoplastic resin in order to improve adhesion. Surface treatment such as chemical treatment or solvent treatment may be appropriately performed. Hereinafter, the adhesive used for sticking a polarizing film and a protective film made of a thermoplastic resin will be described.

[Adhesive comprising curable composition containing active energy ray-curable compound]
An adhesive made of a curable composition containing an active energy ray-curable compound is used for adhering the polarizing film 1 and the protective film 2 made of a thermoplastic resin.

  An active energy ray-curable compound means a compound that can be cured by irradiation with active energy rays. The active energy ray-curable compound may be cationically polymerizable or radically polymerizable. Examples of the cationic polymerizable compound include an epoxy compound having at least one epoxy group in the molecule, an oxetane compound having at least one oxetane ring in the molecule, and the like. Examples of the radical polymerizable compound include (meth) acrylic compounds having at least one (meth) acryloyloxy group in the molecule. The “(meth) acryloyloxy group” means an acryloyloxy group or a methacryloyloxy group.

  The active energy ray-curable compound used for this sticking preferably contains at least an epoxy compound, and thereby exhibits good adhesion between the polarizing film 1 and the protective film 2 made of a thermoplastic resin. . The epoxy compound has at least one epoxy group in the molecule as described above, but it is possible to use an adhesive mainly composed of an epoxy compound having at least two epoxy groups in the molecule. It is particularly preferable for improving the adhesion between the protective film 1 and the protective film 2.

  As an epoxy compound, it is preferable to use the epoxy compound which does not contain an aromatic ring in a molecule | numerator from a viewpoint of a weather resistance, a refractive index, cationic polymerization, etc. as a main component. Examples of the epoxy compound that does not contain an aromatic ring in the molecule include glycidyl ether of a polyol having an alicyclic ring, an aliphatic epoxy compound, and an alicyclic epoxy compound. The epoxy compound suitably used for such a curable adhesive is described in detail in, for example, the above-mentioned Patent Document 1 (Patent No. 4306270), but the outline is also described here.

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

  An aliphatic epoxy compound is a compound having at least one oxirane ring (3-membered cyclic ether) bonded to an aliphatic carbon atom in the molecule. For example, monofunctional epoxy compounds such as butyl glycidyl ether and 2-ethylhexyl glycidyl ether, trifunctional or higher functional epoxy compounds such as trimethylolpropane triglycidyl ether and pentaerythritol tetraglycidyl ether, and 4-vinylcyclohexene dioxide An epoxy compound having one epoxy group directly bonded to an alicyclic ring and an oxirane ring bonded to an aliphatic carbon atom, such as limonene dioxide and limonene dioxide, also corresponds to this, but typically an aliphatic carbon An aliphatic diepoxy compound having two oxirane rings bonded to atoms in the molecule is preferred. Such a suitable aliphatic diepoxy compound can be represented by the following formula (I), for example.

  Y in the formula is an alkylene group having 2 to 9 carbon atoms, an alkylene group having 4 to 9 carbon atoms having an ether bond therebetween, or a divalent hydrocarbon group having 6 to 18 carbon atoms having an alicyclic structure. is there.

  Specifically, the aliphatic diepoxy compound represented by the above formula (I) is a diglycidyl ether of an alkanediol, a diglycidyl ether of an oligoalkylene glycol having up to about 4 repetitions, or a diglycidyl ether of an alicyclic diol. is there.

  Specific examples of the diol (glycol) that can be the aliphatic diepoxy compound represented by the formula (I) are listed below. Examples of alkanediol include ethylene glycol, propylene glycol, 1,3-propanediol, 2-methyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, and 1,4-butanediol. Neopentyl glycol, 3-methyl-2,4-pentanediol, 2,4-pentanediol, 1,5-pentanediol, 3-methyl-1,5-pentanediol, 2-methyl-2,4-pentane Diol, 2,4-diethyl-1,5-pentanediol, 1,6-hexanediol, 1,7-heptanediol, 3,5-heptanediol, 1,8-octanediol, 2-methyl-1,8 -Octanediol, 1,9-nonanediol and the like. Examples of the oligoalkylene glycol include diethylene glycol, triethylene glycol, tetraethylene glycol, and dipropylene glycol. Examples of the alicyclic diol include cyclohexanediol, cyclohexanedimethanol, hydrogenated bisphenol A, and hydrogenated bisphenol F.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

  The compounding amount of the cationic photopolymerization initiator is usually 0.5 to 20 parts by weight, preferably 1 to 6 parts by weight, based on 100 parts by weight of the total of the cationic polymerizable compounds including the epoxy compound and the oxetane compound. is there. If the amount of the cationic photopolymerization initiator is small, the curing becomes insufficient, and the mechanical strength and the adhesion between the polarizing film and the protective film tend to be lowered. On the other hand, if the amount of the cationic photopolymerization initiator is too large, the amount of ionic substances in the cured product will increase, resulting in an increase in the hygroscopicity of the cured product, which may reduce the durability of the resulting adhesive layer. is there.

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

[Protective film made of thermoplastic resin]
The protective film made of a thermoplastic resin is provided on the surface of the polarizing film for the purpose of compensating for the polarizing film made of the polyvinyl alcohol-based resin described above, which has poor physical strength as described above. A protective film made of a thermoplastic resin is bonded to the polarizing film via the curable adhesive containing the active energy ray-curable compound described above, and the curable adhesive is cured to obtain a polarizing plate. The protective film made of thermoplastic resin is composed of acetylcellulose-based resin films including triacetylcellulose, which has been most widely used as protective films for polarizing plates, and resin films with lower moisture permeability than triacetylcellulose. can do. The moisture permeability of triacetyl cellulose is approximately 400g / m ² / 24hr approximately.

  In one preferable form of the present invention, the protective film made of a thermoplastic resin bonded to at least one surface of the polarizing film is composed of an acetylcellulose-based resin film. An acetyl cellulose resin is a resin in which at least a part of hydroxyl groups in cellulose is esterified, and a mixed ester in which part is acetated and partly esterified with another acid. Good. Examples of the acetyl cellulose resin include triacetyl cellulose, diacetyl cellulose, cellulose acetate propionate, and cellulose acetate butyrate.

  The acetyl cellulose resin may contain an ultraviolet absorber. One surface of the polarizing film, specifically, the surface on the side farther from the liquid crystal cell of the polarizing plate bonded to the liquid crystal cell, that is, the surface on the viewing side or the backlight side, is blended with an ultraviolet absorber. The resin film is often pasted as a protective film. As ultraviolet absorbers, salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, and the like are known.

  A thermoplastic resin composed of an acetylcellulose-based resin with a UV absorber blended on one side of the polarizing film, and an acetylcellulose-based with no UV absorber blended on the other side of the polarizing film It is also effective to form a retardation film made of resin and provided with a retardation.

In another preferred embodiment of the present invention, the thermoplastic resin bonded to at least one surface of the polarizing film is composed of a resin film having a moisture permeability lower than that of triacetyl cellulose. As such a resin film, for example, moisture permeability can be cited the following resin film 300g / m ² / 24hr, particularly, amorphous polyolefin resins, polyester resins, acrylic resins, polycarbonate Resin, chain polyolefin resin, etc. correspond to this.

  An amorphous polyolefin-based resin is a polymer having a polymer unit of cycloolefin, such as norbornene, tetracyclododecene (also known as dimethanooctahydronaphthalene), or a compound having a substituent bonded thereto. It may be a copolymer obtained by copolymerizing a chain polyolefin and / or an aromatic vinyl compound. In the case of a homopolymer of cycloolefin or a copolymer of two or more kinds of cycloolefin, a double bond remains by ring-opening polymerization, and hydrogenated one is generally used as an amorphous polyolefin resin. Used for. Of these, thermoplastic norbornene resins are typical.

  The polyester resin is a polymer obtained by condensation polymerization of a dibasic acid and a dihydric alcohol, and polyethylene terephthalate is representative.

  Acrylic resin is a polymer with methyl methacrylate as the main monomer. In addition to methyl methacrylate homopolymer, methyl methacrylate and acrylic esters and aromatic vinyl compounds such as methyl acrylate It may be a copolymer. Acrylic rubber particles may be blended with the acrylic resin for the purpose of improving impact resistance.

  The polycarbonate-based resin is a polymer having a carbonate bond (—O—CO—O—) in the main chain, and is typically obtained by condensation polymerization of bisphenol A and phosgene.

  The chain polyolefin resin is a polymer having a chain olefin such as ethylene or propylene as a main monomer, and can be a homopolymer or a copolymer. Among them, a propylene homopolymer and a copolymer in which a small amount of ethylene is copolymerized with propylene are representative.

  In another preferred embodiment of the present invention, a thermoplastic resin comprising an acetylcellulose-based resin is bonded to one surface of the polarizing film via the adhesive layer, and the adhesive is also applied to the other surface of the polarizing film. The protective film which consists of a transparent thermoplastic resin with low moisture permeability as mentioned above is bonded through a layer.

  The protective film made of a thermoplastic resin is preferably thin, but if it is too thin, the strength tends to decrease and the processability tends to be poor. On the other hand, if it is too thick, the transparency may decrease and the weight of the polarizing plate may increase. Tend to. From such a viewpoint, the thickness of the protective film is usually 10 to 200 μm, preferably 15 to 150 μm, more preferably 20 to 100 μm.

  The protective film made of these thermoplastic resins has a hard coating treatment, an antireflection treatment, an antiglare treatment, an antistatic treatment, or an antifouling treatment on the surface opposite to the surface to be bonded to the polarizing film. Various surface treatments can be applied.

[Production method of polarizing plate]
Next, the manufacturing method of the polarizing plate which concerns on this invention is demonstrated. As described above, in the present invention, the polarizing film 1 is laminated with the protective film 2 made of a thermoplastic resin via an adhesive made of a curable composition containing an active energy ray-curable compound, and irradiated with active energy rays. Then, the adhesive is cured, and the protective film 2 is bonded to the polarizing film 1 to produce a polarizing plate. In that case, before laminating the protective film 2 on the polarizing film 1, the polarizing film 1 is immersed in water. If desired, a protective film 2 made of a thermoplastic resin is bonded to one surface of the polarizing film 1, and a protective film 3 made of another thermoplastic resin is also bonded to the other surface of the polarizing film 1 through an adhesive. Can be combined. After the polarizing film 1 is immersed in water, before adhering the protective film 2 (or 3 if desired), preferably, water adhering to the surface of the polarizing film 1 is removed.

  Then, the manufacturing method of the polarizing plate of this invention passes through the following processes (i)-(iv). However, the water removal step (ii) is optional.

(I) an immersing step of immersing the polarizing film 1 in water;
(Ii) A moisture removal step of taking out the polarizing film 1 after immersion and removing moisture adhered to the film surface;
(Iii) a lamination step of laminating the protective film 2 via the adhesive, after the immersion step (i) or further after the moisture removal step (ii), and (iv) lamination A curing step of curing the adhesive by irradiating the laminate obtained in step (iii) with active energy rays.

  When the protective film 2 made of a thermoplastic resin is bonded to one surface of the polarizing film 1 and the protective film 3 made of another thermoplastic resin is bonded to the other surface, the steps (i) to (iv) May be repeated, or after the immersion step (i) and, if desired, the water removal step (ii), a lamination step (iii) of laminating the protective films 2 and 3 on both surfaces of the polarizing film 1 with an adhesive. ) And then a curing step (iv) in which the adhesives on both sides are simultaneously cured.

  In said coating process (i), the water which immerses the polarizing film 1 does not contain a solute substantially. The phrase “substantially free of solute” as used herein means that a solute contained in the extent of impurities is allowed but not intentionally added. When water (aqueous solution) containing a significant amount of solute is used, the solute remains on the polarizing film 1 and may adversely affect the polarization performance such as the appearance and transparency. The water to be used can be pure water, ultrapure water, tap water or the like, and is not particularly limited. However, from the viewpoint of maintaining the transparency of the polarizing film 1, pure water or ultrapure water is preferable.

  The temperature of the water used is sufficient near room temperature, and is typically about 10 to 40 ° C. When the temperature of the water used for immersion is too high, the polarizing film 1 made of a polyvinyl alcohol-based resin may be melted and the polarizing performance may be lowered. Moreover, what is necessary is just to select the immersion time in water so that the adhesive force of the polarizing film 1 and the protective film 2 may increase compared with the case where this process is not performed, Preferably it shall be 10 second or more. Since the adhesive force between the polarizing film 1 and the protective film 2 tends to increase as the immersion time becomes longer, it is more preferable to immerse in water for 1 minute or longer. There is no special limitation on the upper limit of the immersion time, but if it is too long, the production efficiency is deteriorated, and in some cases, the polarizing film 1 made of polyvinyl alcohol resin may be melted to lower the polarizing performance. 30 minutes or less, more preferably 20 minutes or less, and particularly preferably 10 minutes or less.

  Next, in the water removal step (ii), water attached to the surface of the polarizing film 1 is removed. The operation of removing moisture may be natural drying, but a method of removing moisture while applying air or a method of wiping moisture with a cloth is preferable because moisture can be removed in a short time. In particular, a method of removing moisture while applying wind is more preferable. In the moisture removing step (ii), for example, a method of removing moisture by applying wind while taking out the polarizing film 1 after being immersed in water can be adopted.

  In the laminating step (iii), the protective film 2 made of a thermoplastic resin is bonded to the polarizing film 1 after the immersion step (i) or after the moisture removal step (ii). Laminate. For the formation of the adhesive layer, various coating methods such as a doctor blade, a wire bar, a die coater, a comma coater, and a gravure coater can be used. Moreover, the system which casts an adhesive between it can also be employ | adopted, supplying continuously the polarizing film 1 and the protective film 2 so that both bonding surfaces may become inside. Since each coating system has an optimum viscosity range, it is also a useful technique to adjust the viscosity of the adhesive using a solvent. As the solvent for this purpose, a solvent that dissolves the adhesive satisfactorily without reducing the optical performance of the polarizing film is used, but there is no particular limitation on the type thereof. For example, organic solvents such as hydrocarbons typified by toluene and esters typified by ethyl acetate can be used. The thickness of the adhesive layer is usually 20 μm or less, preferably 10 μm or less, more preferably 5 μm or less, and particularly preferably 2 μm or less. When the adhesive layer becomes thick, the reaction rate of the adhesive decreases, and the heat and humidity resistance of the resulting polarizing plate tends to decrease. After applying the adhesive, the polarizing film 1 and the protective film 2 made of a thermoplastic resin are sandwiched by nip rolls and bonded together. When adopting the method of applying the adhesive with a roll and then spreading it uniformly after dropping the adhesive between the films, the material of the roll used can be metal or rubber, etc. When passing between two rolls The rolls used for may be made of the same material or different materials.

  In said hardening process (iv), an active energy ray is irradiated to the laminated body by which the protective film 2 was laminated | stacked on the polarizing film 1 through the adhesive agent, and an adhesive agent is hardened. The applied active energy rays can be ultraviolet rays, electron rays, X-rays, visible rays, etc., but it is particularly preferable to use a light source having a light emission distribution at a wavelength of 400 nm or less, for example, a low-pressure mercury lamp or a medium-pressure mercury lamp. High pressure mercury lamps, ultra high pressure mercury lamps, chemical lamps, black light lamps, microwave excitation mercury lamps, metal halide lamps, and the like are preferably used as the light source.

The irradiation intensity of the active energy ray to the adhesive is determined for each target composition and is not particularly limited. However, the irradiation intensity of the wavelength region effective for activating the photopolymerization initiator is 0. It is preferable to be 1 to 100 mW / cm ² . If the light irradiation intensity is too small, the reaction time becomes too long. On the other hand, if the light irradiation intensity is too large, the heat of the lamp radiates and the heat generated during polymerization of the adhesive causes yellowing of the adhesive and the polarization film. May cause deterioration. The light irradiation time to the adhesive is also controlled for each composition to be used and is not particularly limited. However, the integrated light amount expressed as the product of the light irradiation intensity and the light irradiation time is 10 to 5,000 mJ / It is preferably set to be cm ² . If the integrated light amount is too small, the generation of active species derived from the initiator may not be sufficient, and the resulting adhesive layer may be insufficiently cured. On the other hand, if the integrated light amount is too large, the light irradiation time Tends to be very long and disadvantageous for productivity improvement.

  When the protective films 2 and 3 are laminated on both surfaces of the polarizing film 1 and active energy rays are irradiated in this state, the active energy rays may be irradiated from either side of the protective film. For example, when one protective film contains an ultraviolet absorber and the other protective film does not contain an ultraviolet absorber, it is preferable to irradiate an active energy ray from the protective film side not containing the ultraviolet absorber. By irradiating in this way, it is possible to effectively use the irradiated active energy rays and increase the curing rate.

[Laminated optical member]
The polarizing plate produced according to the present invention can be formed as a laminated optical member by laminating optical layers having optical functions other than the polarizing plate. Typically, a laminated optical member is obtained by laminating and attaching an optical layer to a protective film of a polarizing plate via an adhesive or a pressure-sensitive adhesive. According to the invention, a protective film may be bonded via a photocurable adhesive, and an optical layer may be laminated and bonded to the other surface of the polarizing film via an adhesive or an adhesive. In the latter case, if a curable composition containing an active energy ray-curable compound is used as an adhesive for adhering the polarizing film and the optical layer, the optical layer is also a protective film as defined in the present invention. Can be.

  As an example of an optical layer laminated on a polarizing plate, a polarizing plate arranged on the back side of the liquid crystal cell is laminated on the side opposite to the side facing the liquid crystal cell of the polarizing plate. Examples include a light plate, a brightness enhancement film, a reflective layer, a transflective layer, and a light diffusion layer. In addition, for both the polarizing plate disposed on the front side of the liquid crystal cell and the polarizing plate disposed on the back side of the liquid crystal cell, a retardation film laminated on the side of the polarizing plate facing the liquid crystal cell, etc. There is.

  The light collector is used for the purpose of optical path control, and may be a prism array sheet, a lens array sheet, or a dot-attached sheet.

  The brightness enhancement film is used for the purpose of improving brightness in a liquid crystal display device. Specifically, a reflective polarized light separation sheet, an alignment film of a cholesteric liquid crystal polymer, and an alignment film that are designed so that anisotropy occurs in the reflectance by laminating a plurality of thin film films having different refractive index anisotropies Examples thereof include a circularly polarized light separating sheet having a liquid crystal layer supported on a film substrate.

  The reflective layer, the transflective layer, or the light diffusing layer is provided to make the polarizing plate into a reflective optical member, a transflective optical member, or a diffusing optical member, respectively. A reflective optical member including a polarizing plate is used in a liquid crystal display device of a type that reflects incident light from the viewing side and displays a light source such as a backlight. Therefore, the liquid crystal display device can be easily thinned. A transflective optical member including a polarizing plate is used as a reflective liquid crystal display device in a bright place and a liquid crystal display device that displays light from a backlight in a dark place. In addition, a diffusing optical member including a polarizing plate is used in a liquid crystal display device that imparts light diffusibility and suppresses display defects such as moire.

  A method for forming these reflective layer, transflective layer, and light diffusion layer will be described. The reflective layer constituting the reflective optical member can be formed, for example, by attaching a foil or a vapor deposition film made of a metal such as aluminum to a protective film on the polarizing film. The semi-transmissive reflective layer constituting the semi-transmissive optical member is formed by using the reflective layer as a half mirror, or by adhering a reflective plate containing a pearl pigment or the like and exhibiting light transmittance to the polarizing plate. it can. The light diffusing layer constituting the diffusing optical member is, for example, a method of performing a mat treatment on a protective film on a polarizing plate, a method of applying a resin containing fine particles, a method of adhering a film containing fine particles, and the like. It can be formed as a surface layer having a fine relief structure. The resin layer or film containing fine particles has an advantage that incident light and its reflected light are diffused when passing through the fine particle-containing layer, and light and dark unevenness can be suppressed. The fine particles to be blended for forming the surface fine concavo-convex structure are, for example, silica, aluminum oxide, titanium oxide, zirconia, tin oxide, indium oxide, cadmium oxide, antimony oxide having an average particle diameter of 0.1 to 30 μm. It can be inorganic fine particles, organic fine particles such as a crosslinked or non-crosslinked polymer, and the like.

  The laminated optical member may be a reflection / diffusion polarizing plate. The reflection / diffusion polarizing plate can be produced by, for example, a method of providing a reflective layer reflecting the uneven structure on the fine uneven structure surface of the diffusion optical member including the polarizing plate. The reflective layer having a fine concavo-convex structure has advantages such that incident light is diffused by irregular reflection, directivity and glare can be prevented, and unevenness in brightness and darkness can be suppressed. The reflective layer reflecting the surface fine concavo-convex structure can be formed by directly attaching a metal to the surface of the fine concavo-convex structure by a method such as vapor deposition or plating such as vacuum deposition, ion plating, or sputtering.

  The retardation film acting as an optical layer is used for the purpose of compensation of retardation by a liquid crystal cell. Examples of retardation plates include birefringent films made of stretched films of various plastics, films in which discotic liquid crystals and nematic liquid crystals are oriented and fixed, and those in which the above liquid crystal layer is formed on a substrate film, etc. Can be mentioned. When the liquid crystal layer is formed on the base film, a cellulose acetate resin film such as triacetyl cellulose is preferably used as the base film.

  Examples of the plastic forming the birefringent film include amorphous polyolefin resins, polycarbonate resins, acrylic resins, chain polyolefin resins such as polypropylene, polyvinyl alcohol, polystyrene, polyarylate, polyamide, and the like. It is done. The stretched film can be processed by an appropriate method such as uniaxial or biaxial. Two or more retardation films may be used in combination for the purpose of controlling optical characteristics such as broadening the bandwidth.

  The laminated optical member is preferable because optical compensation can be effectively performed when a retardation film is applied to the liquid crystal display device as an optical layer other than the polarizing plate. The optimum retardation value (in-plane and thickness direction) of the retardation film may be selected according to the applied liquid crystal cell.

  A laminated optical member can be made into a laminated body of two layers or three or more layers by combining a polarizing plate and one layer or two or more layers selected according to the purpose of use from the various optical layers described above. In that case, the various optical layers forming the laminated optical member are integrated with the polarizing plate using an adhesive or pressure-sensitive adhesive, but the adhesive or pressure-sensitive adhesive layer used for this purpose is good. As long as it is formed, there is no particular limitation. It is preferable to use a pressure-sensitive adhesive (also referred to as a pressure-sensitive adhesive) from the viewpoint of easy bonding work and prevention of optical distortion. Usually, an adhesive layer is also provided on the surface of the laminated optical member to be bonded to the liquid crystal cell.

  As the pressure-sensitive adhesive for integrating the various optical layers and the polarizing plate, those having a base polymer such as an acrylic polymer, a silicone polymer, polyester, polyurethane, or polyether can be used. Above all, like acrylic adhesives, it has excellent transparency, retains appropriate wettability and cohesion, has excellent adhesion to the substrate, and has weather resistance, heat resistance, etc. It is preferable to select and use a material that does not cause separation problems such as floating and peeling under humidification conditions. In acrylic adhesives, alkyl esters of (meth) acrylic acid having an alkyl group having 20 or less carbon atoms such as methyl, ethyl and butyl groups, and (meth) acrylic acid and hydroxyethyl (meth) acrylate An acrylic copolymer having a weight average molecular weight of 100,000 or more, in which a glass transition temperature is preferably 25 ° C. or less, more preferably 0 ° C. or less, and a functional group-containing acrylic monomer comprising Useful as a base polymer.

  The pressure-sensitive adhesive layer is formed on the polarizing plate or the laminated optical member by, for example, preparing a 10 to 40% by weight solution by dissolving or dispersing the pressure-sensitive adhesive composition in an organic solvent such as toluene or ethyl acetate. Direct coating on the target surface of the film (polarizing plate or laminated optical member), or by previously forming an adhesive layer on the protective film and applying it to the target film (polarizing plate or laminated optical member) This can be done by transferring to the surface. The thickness of the pressure-sensitive adhesive layer is determined according to the adhesive force and the like, but a range of about 1 to 50 μm is appropriate.

  In addition, the pressure-sensitive adhesive layer is blended with fillers made of glass fibers, glass beads, resin beads, metal powders and other inorganic powders, pigments, colorants, antioxidants, UV absorbers, etc. as necessary. It may be. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, and nickel complex compounds.

  The laminated optical member can be disposed on one side or both sides of the liquid crystal cell via the above-mentioned pressure-sensitive adhesive layer. The liquid crystal cell to be used is arbitrary. For example, a liquid crystal display device using various liquid crystal cells such as an active matrix drive type typified by a thin film transistor type and a simple matrix drive type typified by a super twisted nematic type. Can be formed.

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

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

[Production Example 2] Preparation of UV curable adhesive The following components were mixed to prepare an UV curable adhesive. “UVACURE 1590” used as a photocationic polymerization initiator was obtained from Daicel Cytec Co., Ltd. in the form of a propylene carbonate solution.

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

[Example 1]
(A) Immersion of Polarizing Film in Water and Removal of Water The polarizing film prepared in Production Example 1 was immersed in pure water at 25 ° C. for 10 seconds. Thereafter, the polarizing film was taken out and air was applied to remove water remaining on the polarizing film. The appearance of the polarizing film thus obtained was visually observed, and the case where no change was observed in the appearance was evaluated as ◯, and the case where foreign matter, unevenness, or discoloration was observed was evaluated as x. The results are shown in Table 1.

(B) Protective film made of thermoplastic resin Corona discharge on the surface of a 40 μm thick retardation film [trade name “N-TAC KC4FR-1”] made of acetylcellulose resin obtained from Konica Minolta Advanced Layer Co., Ltd. The protective film was processed and bonded to one surface of the polarizing film. In addition, the surface of an 80 μm thick triacetyl cellulose film (trade name “Konicatak KC8UX2MW”) containing an ultraviolet absorber obtained from Konica Minolta Advanced Layer Co., Ltd. was subjected to corona discharge treatment, and the other side of the polarizing film It was set as the protective film bonded together.

(C) Production of Polarizing Plate The ultraviolet curable adhesive prepared in Production Example 2 was applied to the corona discharge-treated surfaces of the retardation film and triacetyl cellulose film prepared in (B) above. Each adhesive application surface is bonded to the front and back surfaces of the polarizing film prepared in (A) above, and from the phase difference film side, an ultraviolet irradiation device with a belt conveyor (the lamp is a “D bulb manufactured by Fusion UV Systems”). The adhesive was cured by irradiating with ultraviolet rays so that the integrated light amount was 250 mJ / cm ² . In this way, a polarizing plate having protective films bonded on both sides of the polarizing film was produced.

(D) Evaluation of adhesive strength After performing corona discharge treatment on the retardation film surface comprising the acetylcellulose-based resin of the polarizing plate prepared in (C) above, an acrylic pressure-sensitive adhesive sheet is bonded to the corona discharge treatment surface. did. A test piece having a width of 25 mm and a length of about 200 mm was cut from the obtained polarizing plate with an adhesive. After the pressure-sensitive adhesive surface of the test piece was bonded to soda glass, it was subjected to pressure treatment in an autoclave at a pressure of 5 kgf / cm ² and a temperature of 50 ° C. for 20 minutes, and further in an atmosphere at a temperature of 23 ° C. and a relative humidity of 60%. And left for a day. In this state, using a universal tensile tester ["AG-1" manufactured by Shimadzu Corporation], grab the triacetylcellulose film and polarizing film at one end in the length direction (one side of 25 mm in width), In an atmosphere at a temperature of 23 ° C. and a relative humidity of 55%, in accordance with JIS K6854-2: 1999 “Adhesives-Peeling adhesion strength test method-Part 2: 180 degree peeling” at a gripping movement speed of 300 mm / min. A 180 degree peeling test was performed, and the adhesive force between the polarizing film and the retardation film made of an acetyl cellulose resin was evaluated. The results are shown in Table 1.

[Examples 2 to 5]
Except changing the immersion time to the water of a polarizing film as shown in Table 1, it processed like Example 1 and then produced the polarizing plate. Table 1 shows the results of the appearance evaluation after immersion of the polarizing film in water and the removal of water, and the evaluation of the adhesive strength of the polarizing plate.

[Examples 6 to 7]
Except that the retardation film made of acetylcellulose resin is changed to a 60 μm thick retardation film made of cycloolefin resin, and the immersion time of the polarizing film in water is changed as shown in Table 1. In the same manner as in Example 1, a polarizing plate was produced. Table 1 shows the results of the appearance evaluation after immersion of the polarizing film in water and the removal of water, and the evaluation of the adhesive strength of the polarizing plate.

[Examples 8 to 9]
The retardation film made of an acetyl cellulose resin was changed to an acrylic resin film having a thickness of 80 μm made from a resin composition in which 30% acrylic rubber particles were added to a methyl methacrylate resin. A polarizing plate was produced in the same manner as in Example 1 except that the immersion time was changed as shown in Table 1. Table 1 shows the results of the appearance evaluation after immersion of the polarizing film in water and the removal of water, and the evaluation of the adhesive strength of the polarizing plate.

[Comparative Example 1]
A polarizing plate was produced in the same manner as in Example 1 except that the operation of immersing the polarizing film in water was not performed, and the adhesive strength was evaluated. The results are shown in Table 1. In addition, since the immersion process to water was not performed, the external appearance evaluation result of the polarizing film just before protective film bonding was set to (circle). The same applies to Comparative Examples 2 and 3 below.

[Comparative Example 2]
Except that the operation of immersing the polarizing film in water was not performed, Examples 6 to 7 (the protective film to be attached to the side opposite to the 80 μm-thick triacetylcellulose film was made of cycloolefin resin and had a thickness of 60 μm A polarizing plate was prepared in the same manner as the retardation film, and the adhesive strength was evaluated. The results are shown in Table 1.

[Comparative Example 3]
Except that the operation of immersing the polarizing film in water was not performed, Examples 8 to 9 (the protective film attached to the opposite side of the 80 μm thick triacetyl cellulose film was an 80 μm thick acrylic resin film) Similarly, polarizing plates were prepared and the adhesive strength was evaluated. The results are shown in Table 1.

[Comparative Example 4]
A polarizing plate was produced in the same manner as in Example 1 except that the water to be immersed was changed to a potassium iodide aqueous solution having a concentration of 2% adjusted to pH 8.5 and a temperature of 30 ° C. Table 1 shows the results of appearance evaluation after immersion of the polarizing film in water (potassium iodide aqueous solution) and removal of water, and evaluation of adhesive strength in the polarizing plate. In Table 1, “KI solution” in the “water state” column means an aqueous potassium iodide solution. The same applies to Comparative Examples 5 to 7 below.

[Comparative Example 5]
A polarizing plate was produced in the same manner as in Comparative Example 4 except that the polarizing film after being immersed in an aqueous potassium iodide solution was dried in an oven at 60 ° C. for 4 minutes. Table 1 shows the results of the appearance evaluation after immersion and drying of the polarizing film in water (potassium iodide aqueous solution) and the adhesive strength evaluation in the polarizing plate.

[Comparative Example 6]
Comparative example except that the retardation film made of acetyl cellulose resin is changed to an acrylic resin film having a thickness of 80 μm made from a resin composition in which 30% acrylic rubber particles are blended with methyl methacrylate resin. In the same manner as in Example 4, a polarizing plate was produced. Table 1 shows the results of appearance evaluation after immersion of the polarizing film in water (potassium iodide aqueous solution) and removal of water, and evaluation of adhesive strength in the polarizing plate.

[Comparative Example 7]
A polarizing plate was produced in the same manner as in Comparative Example 6 except that the polarizing film after the treatment of immersing in an aqueous potassium iodide solution was dried in an oven at 60 ° C. for 4 minutes. Table 1 shows the results of the appearance evaluation after immersion and drying of the polarizing film in water (potassium iodide aqueous solution) and the adhesive strength evaluation in the polarizing plate.

  As can be seen from Table 1, in Comparative Example 1 using a polarizing film that has not been immersed in water, the adhesive force between the polarizing film and a retardation film made of an acetylcellulose-based resin is low. On the other hand, after performing the operation which immerses a polarizing film in water, in Examples 1-5 which pasted up a protective film via an adhesive agent, it is between phase contrast films which consist of a polarizing film and an acetylcellulose system resin. Adhesive strength has increased dramatically. Moreover, it turns out that the adhesive force becomes high, so that the immersion time in water becomes long. Comparative Example 2 and Examples 6 to 7 in which the retardation film made of acetylcellulose resin is changed to a retardation film made of cycloolefin resin, and Comparative Example 3 and Examples 8 to 9 in which acrylic resin film is changed. But similar results have been obtained.

  On the other hand, in Comparative Examples 4 to 7 in which immersion treatment was performed using water containing a solute (potassium iodide), the appearance of the polarizing film after moisture removal was deteriorated. This change in appearance is considered to be caused by a solute contained in water.

1 …… Polarizing film,
2, 3 ... Protective film made of thermoplastic resin,
4, 5 ... Adhesive layer.

Claims (5)

A polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol-based resin and a protective film made of a thermoplastic resin is bonded to the polarizing film through an adhesive, and a polarizing plate is produced,
The adhesive comprises a curable composition containing an active energy ray-curable compound,
The protective film is a film made of an acetyl cellulose resin, an amorphous polyolefin resin, a polyester resin, an acrylic resin, a polycarbonate resin, or a chain polyolefin resin,
Through the steps including the following (1) to (4), a polarizing film is obtained,
(1) Step of uniaxially stretching a polyvinyl alcohol-based resin
(2) Dyeing process of dyeing polyvinyl alcohol resin with dichroic dye to adsorb dichroic dye
(3) A boric acid treatment step of treating a polyvinyl alcohol resin adsorbed with a dichroic dye with an aqueous boric acid solution.
(4) A water washing step of washing the polyvinyl alcohol resin after the boric acid treatment step
An immersion step of immersing the obtained polarizing film in water,
A laminating step of laminating the protective film via the adhesive on the polarizing film after the immersion step, and a curing step of curing the adhesive by irradiating the laminate obtained in the laminating step with active energy rays The manufacturing method of the polarizing plate characterized by the above-mentioned. The manufacturing method according to claim 1, wherein the active energy ray-curable compound is a cationic polymerization compound.   The manufacturing method according to claim 1 or 2, further comprising a drying treatment step after the water washing step. The said immersion process is a manufacturing method in any one of Claims 1-3 performed by immersing the said polarizing film in water for 1 minute or more. The manufacturing method in any one of Claims 1-4 provided with the water | moisture-content removal process of removing the water | moisture content adhering to the surface of the said polarizing film between the said immersion process and the said lamination | stacking process.

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