JP5267920B2 - Polarizing plate, method for manufacturing the same, and liquid crystal display device - Google Patents

Abstract

The invention relates to a polaroid sheet, a manufacturing method thereof and a liquid crystal display device using the polaroid sheet. The polaroid sheet is provided with a polarizing film (51) whichhas oriented dichroism pigment absorbed on a polyvinyl alcohol resin film, a first protective layer (52) which is stacked on one side of the polarizing film (51) and is made from condensate containing solidifying composition with active energy line, and a second protective layer (53) which is stacked on the other side of the polarizing film (51) by an adhesive layer (54) and is made from thermoplastic resin film.

Description

  The present invention relates to a polarizing plate, particularly a polarizing plate suitably used for a liquid crystal display device in a transverse electric field (IPS) mode, a manufacturing method thereof, and a liquid crystal display device operating in a transverse electric field mode using the polarizing plate. .

  In recent years, due to various advantages such as low power consumption, low voltage operation, light weight, and thin shape, a liquid crystal display (LCD) is used for information such as a mobile phone, a personal digital assistant (PDA), a personal computer, and a television. Applications as display devices are increasing rapidly. With the development of liquid crystal display technology, liquid crystal display devices of various modes have been proposed, and problems of LCD such as response speed, contrast, and narrow viewing angle are being solved.

  As one of the countermeasures for viewing angle compensation, a liquid crystal cell capable of essentially expanding the viewing angle has been proposed. Examples thereof include an optically compensated bend (OCB) mode, a vertical alignment (VA) mode, and an in-plane switching (IPS) mode. Among these, the IPS mode changes the alignment state of liquid crystal molecules by a lateral electric field in which a voltage is applied in a direction parallel to the substrate surface. In the IPS mode, the liquid crystal molecules are aligned in parallel to the substrate surface when no voltage is applied, but are not twisted as in the TN mode but are aligned in substantially the same direction.

  The principle of the IPS mode will be described with reference to FIGS. FIG. 1 is a schematic cross-sectional view illustrating a configuration example of an IPS mode liquid crystal display device, and FIG. 2 is a schematic perspective view illustrating an example of normally black in order to explain the principle of the IPS mode. A) shows a state when no voltage is applied, and (B) shows a state when a voltage is applied. In FIG. 2, the layers are displayed separately for easy understanding. In FIG. 2B, reference numerals are given only to parts that are in a different state from (A), and parts in the same state as (A) are designated by reference numerals in order to avoid difficulty in viewing the drawing. Is omitted.

  Referring to FIG. 1, a liquid crystal cell 10 that forms the center of an IPS mode liquid crystal display device includes upper and lower cell substrates 11 and 12 and a liquid crystal layer 14 sandwiched between these cell substrates. The liquid crystal molecules 15 constituting the liquid crystal layer 14 are aligned substantially parallel to the surfaces of the cell substrates 11 and 12. A front-side polarizing plate 20 and a rear-side polarizing plate 30 are disposed above and below the liquid crystal cell 10 respectively. Of the light from the backlight 40 disposed on one outer side (back side), the liquid crystal cell. Only the linearly polarized light parallel to the transmission axis of the back-side polarizing plate 30 between 10 and the backlight 40 is incident on the liquid crystal cell 10.

  Next, in a state where no voltage is applied as shown in FIG. 2A, the liquid crystal molecules 15 are aligned in parallel and substantially in the same direction with respect to the cell substrate surface. In this example, the liquid crystal molecules 15 are aligned in a direction substantially parallel to the transmission axis 32 of the back side polarizing plate 30. One cell substrate (lower substrate in this example) 12 is provided with electrodes 13 and 13 in parallel in a comb shape. In this state, the linearly polarized light 16 transmitted through the back side polarizing plate 30 passes through the liquid crystal layer 14 without changing its polarization state as it is, and the upper cell substrate 11 in the state of the linearly polarized light 17 in the same direction as the incident state. Pass through. If the transmission axis 22 of the front-side polarizing plate 20 disposed thereon is orthogonal to the transmission axis 32 of the rear-side polarizing plate 30, the linearly polarized light 17 that has passed through the upper cell substrate 11 becomes the front-side polarizing plate. 20 cannot be passed and a black state is displayed.

  On the other hand, as shown in FIG. 2B, when an electric field 18 indicated by a broken line is applied between the electrodes 13 and 13 arranged in parallel on the cell substrate, the long axis of the liquid crystal molecules 15 18 and is displaced from the transmission axis 32 of the back-side polarizing plate 30. As a result, the polarization state of the linearly polarized light 16 incident on the liquid crystal cell 10 changes in the polarization state while passing through the liquid crystal layer 14, and after passing through the liquid crystal layer 14, becomes an elliptically polarized light 17 ′. A component that can pass through 22 is produced, thus displaying a bright state.

  In FIG. 2, the transmission axis 32 of the back side polarizing plate 30 is arranged so as to be substantially parallel to the long axis of the liquid crystal molecules 15, and the transmission axes of the front side polarizing plate 20 and the back side polarizing plate 30 are orthogonal to each other. However, the transmission axis 22 of the front-side polarizing plate 20 is arranged so as to be substantially parallel to the long axis of the liquid crystal molecules 15, and the transmission axes of the front-side polarizing plate 20 and the rear-side polarizing plate 30 are Similar results can be obtained even if they are arranged orthogonally. In short, the liquid crystal molecules 15 may be arranged so that the major axis thereof is substantially parallel to the transmission axis of one of the polarizing plates. At this time, the major axis direction of the liquid crystal molecules 15 and the transmission axis of one of the polarizing plates do not need to be strictly parallel, but rather the liquid crystal molecules 15 rotate in a certain direction when the electric field 18 is applied. In some cases, the angle may be shifted by a certain angle, for example, an angle within 10 °. Further, by arranging so that the transmission axes of the front-side polarizing plate 20 and the rear-side polarizing plate 30 are orthogonal, a black state is displayed when no voltage is applied, and a bright state is displayed when a voltage is applied. However, if the transmission axes of the front-side polarizing plate 20 and the rear-side polarizing plate 30 are arranged in parallel, a bright state is displayed when no voltage is applied, and a black state is displayed when a voltage is applied. It becomes.

As described above, in the IPS mode, liquid crystal molecules are aligned in the same direction in parallel with the substrate surface, and therefore, the viewing angle characteristics are excellent compared to other modes. However, triacetyl cellulose film which has been conventionally used as a protective film of a polarizing plate is between the liquid crystal cell and the polarizing film, retardation R _e is approximately 5nm approximately in the plane, in the thickness direction retardation R _th is approximately 50nm It is. For this reason, there is a problem that transmitted light causes birefringence and light leaks during black display.

To solve such a problem, for example, Patent Document 1, to prepare a small transparent film having retardation R _th retardation R _e and the thickness direction of the plane, a technique used as a protective film of a polarizing plate is disclosed Yes.

On the other hand, in order to make the protective film of the polarizing plate thin, for example, in Patent Document 2, an uncured epoxy resin composition is applied to at least one surface of a polarizing film in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin. A technique for forming a protective film by curing the composition after being worked is disclosed. However, a polarizing plate using a cured product of an epoxy resin composition as a protective film does not have sufficient durability, for example, it cannot sufficiently suppress shrinkage of the polarizing film under high temperature conditions, and has a size exceeding 15 inches. The polarizing plate has a problem that the polarizing film is broken.
JP 2006-18245 A JP 2004-245924 A

An object of the present invention is a polarizing plate as a retardation R _th substantially zero retardation R _e and the thickness direction of the plane of the protective layer disposed on the liquid crystal cell side, further excellent thin and light resistance and durability An object of the present invention is to provide a polarizing plate suitably used for a polarizing plate, particularly a liquid crystal display device in a transverse electric field (IPS) mode, and a method for producing the same. Another object of the present invention is to provide a liquid crystal display device using such a polarizing plate, particularly a liquid crystal display device operating in a transverse electric field mode.

  The present invention is a curing of a curable resin composition containing a polarizing film having a dichroic dye adsorbed and oriented on a polyvinyl alcohol resin and an active energy ray-curable compound laminated on one surface of the polarizing film. There is provided a polarizing plate comprising a first protective layer made of a product and a second protective layer made of a thermoplastic resin film laminated on the other surface of the polarizing film via an adhesive layer.

In the polarizing plate of the present invention, the active energy ray-curable compound forming the first protective layer contains an epoxy compound having at least one epoxy group in the molecule . The epoxy compound is good preferable to have at least one epoxy group bonded to a cycloaliphatic ring.

  The active energy ray-curable resin compound may further contain an oxetane compound. The active energy ray-curable compound may further include a (meth) acrylic compound having at least one (meth) acryloyloxy group in the molecule.

  The first protective layer made of a cured product of the curable resin composition preferably has a thickness of 0.1 to 10 μm.

  It is preferable that a 2nd protective layer consists of a cellulose acetate type-resin film. Moreover, it is preferable that an adhesive bond layer consists of hardened | cured material of curable resin composition containing an active energy ray curable compound.

  The polarizing plate of the present invention may further include an adhesive layer laminated on the surface of the first protective layer opposite to the polarizing film side. The polarizing plate of the present invention is suitably used for a liquid crystal display device that operates in a transverse electric field mode.

  Moreover, this invention is equipped with a liquid crystal cell and a pair of polarizing plate arrange | positioned on both surfaces of this liquid crystal cell, At least one is a polarizing plate of this invention provided with the said adhesive layer among the said pair of polarizing plates. A liquid crystal display device bonded to the liquid crystal cell on the pressure-sensitive adhesive layer side, a liquid crystal cell, and a pair of polarizing plates disposed on both surfaces of the liquid crystal cell, the pair of polarizing plates Is a polarizing plate of the present invention provided with the pressure-sensitive adhesive layer, and provides a liquid crystal display device bonded to the liquid crystal cell on the pressure-sensitive adhesive layer side.

  The liquid crystal cell in the liquid crystal display device of the present invention is a transverse electric field mode having two substrates and a liquid crystal layer sandwiched between the substrates and aligned substantially parallel to the substrate when no voltage is applied. A liquid crystal cell that operates is preferable.

  Further, according to the present invention, curing of a curable resin composition containing an active energy ray-curable compound laminated on one surface of a polarizing film and a polarizing film having a dichroic dye adsorbed and oriented on a polyvinyl alcohol resin. A method for producing a polarizing plate comprising: a first protective layer made of a product; and a second protective layer made of a thermoplastic resin film laminated on the other surface of the polarizing film via an adhesive layer. A coating layer forming step of providing a coating layer of the curable resin composition on the surface of the substrate, and a coating layer of the curable resin composition provided on the surface of the substrate is bonded to one surface of the polarizing film A coating layer bonding step, a film bonding step for bonding the second protective layer to the other surface of the polarizing film via an adhesive, a curing step for curing the coating layer and the adhesive, and a base A base material removal step for removing the material; Method for manufacturing a polarizing plate comprising a are provided.

  The curing of the coating layer and the adhesive in the curing step is preferably performed simultaneously by irradiating active energy rays from the substrate side.

The polarizing plate of the present invention comprises a first protective layer is a retardation R _e and the thickness direction retardation R _th substantially zero in the plane. Therefore, when such a polarizing plate of the present invention is applied to a liquid crystal display device such that the first protective layer is on the liquid crystal cell side, light leakage can be effectively prevented. In addition, since the first protective layer is composed of a cured product of the curable resin composition, the thickness of the protective layer can be reduced as compared with a conventional triacetyl cellulose (TAC) film. Weight reduction can be achieved.

  Moreover, according to the manufacturing method of the polarizing plate of this invention, it is possible to manufacture the polarizing plate which concerns on this invention, without providing a drying process, and can aim at simplification of a manufacturing process.

<Polarizing plate>
FIG. 3 is a schematic cross-sectional view showing a preferred example of the polarizing plate according to the present invention. 3 includes a polarizing film 51, a transparent first protective layer 52 laminated on one surface of the polarizing film 51, and a transparent second protective layer laminated on the other surface. 53. The 1st protective layer 52 consists of hardened | cured material of the curable resin composition containing an active energy ray curable compound. The second protective layer 53 is made of a thermoplastic resin film, and is bonded to the polarizing film 51 via the adhesive layer 54. The polarizing plate 50 is an adhesive layer for bonding to a liquid crystal cell or the like on the outer side of the first protective layer 52, that is, the surface of the first protective layer 52 opposite to the polarizing film 51 side. 55. In addition, the polarizing plate of this invention does not need to have an adhesive layer. Hereinafter, the polarizing plate of the present invention will be described in detail.

(Polarizing film)
A polarizing film that exhibits a function as a polarizing plate is one in which a dichroic dye is adsorbed and oriented on a polyvinyl alcohol resin. The polyvinyl alcohol resin constituting the polarizing film can be obtained by saponifying a polyvinyl acetate resin. Examples of the polyvinyl acetate resin include polyvinyl acetate, which is a homopolymer of vinyl acetate, and copolymers of vinyl acetate and other monomers copolymerizable therewith. Examples of other monomers copolymerizable with vinyl acetate include unsaturated carboxylic acids, unsaturated sulfonic acids, olefins, vinyl ethers, and the like. The saponification degree of the polyvinyl alcohol-based resin is usually about 85 to 100 mol%, preferably 98 to 100 mol%. The polyvinyl alcohol-based resin may be further modified, and for example, polyvinyl formal or polyvinyl acetal modified with aldehydes may be used. The degree of polymerization of the polyvinyl alcohol resin is usually about 1,000 to 10,000, preferably about 1,500 to 10,000.

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

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

  Uniaxial stretching may be performed before dyeing with the dichroic dye, may be performed simultaneously with the dyeing, or may be performed after the dyeing. When uniaxial stretching is performed after dyeing with a dichroic dye, the uniaxial stretching may be performed before boric acid treatment or during boric acid treatment. Moreover, it is also possible to perform uniaxial stretching in these several steps. In uniaxial stretching, it may be uniaxially stretched between rolls having different peripheral speeds, or may be uniaxially stretched using a hot roll. Further, it may be dry stretching such as stretching in the air, or may be wet stretching in which stretching is performed in a state swollen with a solvent. The draw ratio is usually about 4 to 8 times.

  In order to dye the polyvinyl alcohol resin film with the dichroic dye, for example, the polyvinyl alcohol resin film may be immersed in an aqueous solution containing the dichroic dye. As the dichroic dye, iodine, a dichroic dye or the like is used. In addition, it is preferable that the polyvinyl alcohol-type resin film performs the immersion process to water before a dyeing process.

  When iodine is used as the dichroic dye, a method of immersing a polyvinyl alcohol-based resin film in an aqueous solution containing iodine and potassium iodide is usually employed as a dyeing method. The content of iodine in this aqueous solution is usually about 0.01 to 0.5 parts by weight with respect to 100 parts by weight of water, and the content of potassium iodide is usually 0.00 with respect to 100 parts by weight of water. About 5 to 10 parts by weight. The temperature of the aqueous solution used for dyeing is usually about 20 to 40 ° C., and the immersion time (dyeing time) in this aqueous solution is usually about 30 to 300 seconds.

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

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

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

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

(Protective layer)
In this invention, the 1st protective layer provided in one side of the above polarizing films is comprised with the hardened | cured material of the curable resin composition containing an active energy ray curable compound. Moreover, the 2nd protective layer provided in the other surface of a polarizing film comprises a thermoplastic resin film, and bonds the thermoplastic resin film to the said other surface of a polarizing film through an adhesive bond layer. Hereinafter, the description proceeds in the order of the first protective layer and the second protective layer.

(1) 1st protective layer The 1st protective layer provided in one surface of a polarizing film is comprised with the hardened | cured material of the curable resin composition containing an active energy ray curable compound as above-mentioned. The active energy ray-curable compound means a compound that can be cured by irradiation with active energy rays (for example, ultraviolet rays, visible light, electron beams, X-rays, etc.). The active energy ray-curable compound, there are those of the cationically polymerizable, and those of the radical polymerizability. Examples of the cationically polymerizable compound include an epoxy compound having at least one epoxy group in the molecule (hereinafter sometimes simply referred to as “epoxy compound”), and an oxetane having at least one oxetane ring in the molecule. And the like (hereinafter sometimes simply referred to as “oxetane compounds”). Examples of radically polymerizable compounds include (meth) acrylic compounds having at least one (meth) acryloyloxy group in the molecule (hereinafter sometimes simply referred to as “(meth) acrylic compounds”), etc. Can be mentioned. The “(meth) acryloyloxy group” means a methacryloyloxy group or an acryloyloxy group.

A cured product obtained by irradiating an active energy ray to such a curable resin composition containing an active energy ray-curable compound is excellent in transparency, mechanical strength, thermal stability, and the like. A protective layer having a retardation value R _e in the plane of the film (first protective layer) defined in 1) and a retardation value R _th in the film thickness direction defined by the following formula (2) is almost zero. Here, almost zero, in R _e is in the range of 0 ≦ R _e ≦ 20, more preferably 0 ≦ R _e ≦ 15, further preferably 0 ≦ R _e ≦ 10. Further, almost zero in R _{th is} in the range of | R _th | ≦ 25, more preferably | R _th | ≦ 23, and more preferably | R _th | ≦ 20.

_{R e = (n x -n y} ) × d (1)
_Rth = [( _nx + _ny ) / 2- _nz ] * d (2)
Here, n _x: plane slow axis direction of the refractive index n _y in the film refractive index n _z in the in-plane fast axis direction of the film (the direction perpendicular to the slow axis direction): refraction in the thickness direction of the film Rate d: film thickness

By the first protective layer, a retardation value R _e and film thickness direction of the retardation value R _th substantially zero in the film plane, constituting a cured product of the curable resin composition, the first polarizer When bonded to the liquid crystal cell on the one protective layer side, light leakage during black display in the obtained liquid crystal display device can be effectively prevented. Further, since the thickness of the protective layer can be reduced, it is possible to reduce the thickness and weight of the polarizing plate and the liquid crystal display device.

  Further, since the protective layer laminated on the polarizing film is preferably optically transparent, the haze value of the first protective layer is preferably 0.5% or less, and 0.3% or less. It is more preferable that it is 0.1% or less. If the haze value exceeds 0.5%, light is scattered and the transmittance is lowered.

The active energy ray-curable compound used in the present invention contains at least an epoxy compound . Thereby, the protective layer which shows favorable adhesiveness with respect to a polarizing film is obtained.

  As the epoxy compound, it is preferable to use, as a main component, an epoxy compound that does not contain an aromatic ring in the molecule from the viewpoints of weather resistance, refractive index, cationic polymerization, and the like. Examples of such epoxy compounds that do not contain an aromatic ring in the molecule include hydrogenated epoxy compounds, aliphatic epoxy compounds, alicyclic epoxy compounds, and the like.

  The hydrogenated epoxy compound can be obtained by selectively hydrogenating an aromatic epoxy compound in the presence of a catalyst under pressure. Examples of aromatic epoxy compounds include bisphenol-type epoxy resins such as diglycidyl ether of bisphenol A, diglycidyl ether of bisphenol F, and diglycidyl ether of bisphenol S; phenol novolac epoxy resins, cresol novolac epoxy resins, hydroxy Examples include novolak-type epoxy resins such as benzaldehyde phenol novolac epoxy resins; glycidyl ethers of tetrahydroxydiphenylmethane, glycidyl ethers of tetrahydroxybenzophenone, and polyfunctional epoxy resins such as epoxidized polyvinylphenol. Of these, hydrogenated bisphenol A glycidyl ether is preferably used as the hydrogenated epoxy compound.

  Examples of the aliphatic epoxy compound include polyglycidyl ethers of aliphatic polyhydric alcohols or alkylene oxide adducts thereof. More specifically, 1,4-butanediol diglycidyl ether, 1,6-hexanediol diglycidyl ether, glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, polyethylene glycol diglycidyl ether, propylene Polyethers of polyether polyols obtained by adding one or more alkylene oxides (ethylene oxide or propylene oxide) to aliphatic polyhydric alcohols such as glycol diglycidyl ether, ethylene glycol, propylene glycol and glycerin Examples thereof include glycidyl ether.

  The alicyclic epoxy compound means an epoxy compound having at least one epoxy group bonded to the alicyclic ring. The “epoxy group bonded to the alicyclic ring” has a structure represented by the following formula, wherein m is an integer of 2 to 5.

Therefore, the alicyclic epoxy compound is a compound having at least one structure represented by the above formula in the molecule. More specifically, a compound in which one or a plurality of hydrogen groups in (CH ₂ ) _m in the above formula are bonded to another chemical structure can be an alicyclic epoxy compound. One or more hydrogen atoms in (CH ₂ ) _m may be appropriately substituted with a linear alkyl group such as a methyl group or an ethyl group.

  Among the epoxy compounds as described above, an alicyclic epoxy compound, that is, a compound in which at least one of the epoxy groups is bonded to the alicyclic ring is preferable, and in particular, an oxabicyclohexane ring (in the above formula) An epoxy compound having m = 3) or an oxabicycloheptane ring (m = 4 in the above formula) has a high elastic modulus of the cured product, and a protective layer excellent in adhesion to the polarizing film can be obtained. Since it is easy, it is used more preferably. Although the structure of the alicyclic epoxy compound preferably used in the present invention is specifically exemplified below, it is not limited to these compounds.

  (A) Epoxycyclohexylmethyl epoxycyclohexanecarboxylates represented by the following formula (I):

(In the formula, R ¹ and R ² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)

  (B) Epoxycyclohexanecarboxylates of alkanediol represented by the following formula (II):

(In the formula, R ³ and R ⁴ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and n represents an integer of 2 to 20).

  (C) Epoxycyclohexylmethyl esters of dicarboxylic acid represented by the following formula (III):

(In the formula, R ⁵ and R ⁶ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and p represents an integer of 2 to 20).

  (D) Epoxycyclohexyl methyl ethers of polyethylene glycol represented by the following formula (IV):

(In the formula, R ⁷ and R ⁸ independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and q represents an integer of 2 to 10).

  (E) Epoxycyclohexyl methyl ethers of alkanediols represented by the following formula (V):

(In the formula, R ⁹ and R ¹⁰ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms, and r represents an integer of 0 to 18).

  (F) Diepoxy trispiro compound represented by the following formula (VI):

(In the formula, R ¹¹ and R ¹² each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)

  (G) Diepoxy monospiro compound represented by the following formula (VII):

(In the formula, R ¹³ and R ¹⁴ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)

  (H) Vinylcyclohexene diepoxides represented by the following formula (VIII):

(In the formula, R ¹⁵ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)

  (I) Epoxycyclopentyl ethers represented by the following formula (IX):

(In the formula, R ¹⁶ and R ¹⁷ each independently represent a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)

  (J) Diepoxytricyclodecanes represented by the following formula (X):

(In the formula, R ¹⁸ represents a hydrogen atom or a linear alkyl group having 1 to 5 carbon atoms.)

  Among the alicyclic epoxy compounds exemplified above, the following alicyclic epoxy compounds are commercially available or similar, and are preferably used because they are relatively easy to obtain. It is done.

(A) Esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (7-oxa-bicyclo [4.1.0] hept-3-yl) methanol [formula (I ) In which R ¹ = R ² = H],
(B) 4-methyl-7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and (4-methyl-7-oxa-bicyclo [4.1.0] hept-3-yl) methanol Esterified product [compound of the above formula (I), R ¹ = 4-CH ₃ , R ² = 4-CH ₃ ],
(C) Esterified product of 7-oxabicyclo [4.1.0] heptane-3-carboxylic acid and 1,2-ethanediol [in the above formula (II), R ³ = R ⁴ = H, n = 2 Compound of
(D) (7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [in the above formula (III), R ⁵ = R ⁶ = H, p = 4 compound ],
(E) (4-Methyl-7-oxabicyclo [4.1.0] hept-3-yl) esterified product of methanol and adipic acid [in the above formula (III), R ⁵ = 4-CH ₃ , R ⁶ = 4-CH ₃ , p = 4 compound]
(F) Etherified product of (7-oxabicyclo [4.1.0] hept-3-yl) methanol and 1,2-ethanediol [in the above formula (V), R ⁹ = R ¹⁰ = H, r = 2 compounds].

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

  In the curable resin composition used for forming the first protective layer, the epoxy compound is preferably contained in a proportion of 30 to 100% by weight in the active energy ray curable compound. More preferably, it is contained in a proportion of 40 to 60% by weight. When content of an epoxy-type compound is less than 30 weight%, there exists a tendency for the adhesiveness of a polarizing film and a 1st protective layer to fall.

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

  An 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-based compounds can be easily obtained as commercial products. For example, all of these oxetane compounds are trade names such as “Aron Oxetane OXT-101”, “Aron Oxetane OXT-121”, “Aron Oxetane OXT-211”. ”,“ Aron Oxetane OXT-221 ”,“ Aron Oxetane OXT-212 ”(all manufactured by Toagosei Co., Ltd.), and the like. Although the compounding quantity of an oxetane type compound is not specifically limited, Usually, it is 30 weight% or less in an active energy ray hardening compound, Preferably it is 10-25 weight%.

  When the curable resin composition used for forming the first protective layer contains a cationic polymerizable compound such as an epoxy compound or an oxetane compound, the curable resin composition usually contains a photocation polymerization initiator. Is done. When a cationic photopolymerization initiator is used, it becomes possible to form a protective layer at room temperature, so the need to consider the heat resistance of the polarizing film and distortion due to expansion is reduced, and the first protective layer has good adhesion and the polarizing film. Can be formed on top. Moreover, since a photocationic polymerization initiator acts catalytically by light, it is excellent in storage stability and workability even when mixed with a curable resin composition.

  The cationic photopolymerization initiator generates a cationic species or a Lewis acid upon irradiation with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams, and initiates a polymerization reaction of an epoxy compound and / or an oxetane compound. Is. In the present invention, any type of photocationic polymerization initiator may be used. Specific examples include, for example, onium salts such as aromatic diazonium salts, aromatic iodonium salts, aromatic sulfonium salts, iron- Examples include allene complexes.

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

  Examples of the aromatic iodonium salt include diphenyliodonium tetrakis (pentafluorophenyl) borate, diphenyliodonium hexafluorophosphate, diphenyliodonium hexafluoroantimonate, di (4-nonylphenyl) iodonium hexafluorophosphate, and the like.

  Examples of the aromatic sulfonium salt include triphenylsulfonium hexafluorophosphate, triphenylsulfonium hexafluoroantimonate, triphenylsulfonium tetrakis (pentafluorophenyl) borate, 4,4′-bis [diphenylsulfonio] diphenyl sulfide bishexa. Fluorophosphate, 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bishexafluoroantimonate, 4,4′-bis [di (β-hydroxyethoxy) phenylsulfonio] diphenylsulfide bis Hexafluorophosphate, 7- [di (p-toluyl) sulfonio] -2-isopropylthioxanthone hexafluoroantimonate, 7- [di (p-tolui) ) Sulfonio] -2-isopropylthioxanthone tetrakis (pentafluorophenyl) borate, 4-phenylcarbonyl-4′-diphenylsulfonio-diphenyl sulfide hexafluorophosphate, 4- (p-tert-butylphenylcarbonyl) -4′-diphenyl Examples include sulfonio-diphenyl sulfide hexafluoroantimonate, 4- (p-tert-butylphenylcarbonyl) -4′-di (p-toluyl) sulfonio-diphenyl sulfide tetrakis (pentafluorophenyl) borate.

  Examples of the iron-allene complex include xylene-cyclopentadienyl iron (II) hexafluoroantimonate, cumene-cyclopentadienyl iron (II) hexafluorophosphate, xylene-cyclopentadienyl iron (II). -Tris (trifluoromethylsulfonyl) methanide and the like.

  These photocationic polymerization initiators can be easily obtained as commercial products. For example, “Kayarad PCI-220” and “Kayarad PCI-620” (Nippon Kayaku Co., Ltd. )), “UVI-6990” (manufactured by Union Carbide), “Adekaoptomer SP-150”, “Adekaoptomer SP-170” (manufactured by ADEKA, Inc.), “CI-5102”, “ "CIT-1370", "CIT-1682", "CIP-1866S", "CIP-2048S", "CIP-2064S" (Nippon Soda Co., Ltd.), "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” (manufactured by Midori Chemical Co., Ltd.), “PI-2074” (manufactured by Rhodia), “UVACURE 1590” (manufactured by Daicel Cytec Co., Ltd.), and the like.

  These cationic photopolymerization initiators may be used alone or in combination of two or more. Among these, aromatic sulfonium salts, in particular, have ultraviolet absorption characteristics even in the wavelength region of 300 nm or more, and therefore, cured products having excellent curability and good mechanical strength and good adhesion to polarizing films. Since it can be given, it is preferably used.

  The compounding quantity of a photocationic polymerization initiator is 0.5-20 weight part normally with respect to 100 weight part of total amounts of cation polymerizable compounds, such as an epoxy-type compound and an oxetane type compound, Preferably it is 1-6 weight. Part. When the blending amount of the cationic photopolymerization initiator is less than 0.5 parts by weight with respect to 100 parts by weight of the total amount of the cationic polymerizable compound, curing becomes insufficient, and mechanical strength and the protective layer and the polarizing film There exists a tendency for adhesiveness to fall. On the other hand, if the amount of the cationic photopolymerization initiator exceeds 20 parts by weight with respect to 100 parts by weight of the total amount of the cationic polymerizable compound, the ionic substance in the cured product increases and the hygroscopic property of the cured product increases. And the durability of the resulting polarizing plate may be reduced.

  Moreover, the curable resin composition used for forming the first protective layer contains a radically polymerizable (meth) acrylic compound together with the epoxy compound, or together with the epoxy compound and the oxetane compound. Is preferred. By using the (meth) acrylic compound in combination, it is possible to obtain a protective layer having high hardness, excellent mechanical strength, and higher durability. Furthermore, adjustments such as the viscosity and curing rate of the curable resin composition, the surface curability of the resulting protective layer, and the adhesion to the polarizing film can be more easily performed.

  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) methacrylate having two (meth) acryloyloxy groups in the molecule. ) Acrylate monomers and polyfunctional (meth) acrylate monomers having 3 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, 2-hydroxybutyl (meth) acrylate 2-hydroxy-3-phenoxypropyl (meth) acrylate, isobutyl (meth) acrylate, t-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 Include ethyl carbitol (meth) acrylate, trimethylolpropane mono (meth) acrylate, pentaerythritol mono (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate and the like.

  Moreover, a carboxyl group-containing (meth) acrylate monomer may be used as the monofunctional (meth) acrylate monomer. 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 and epoxy di (meth) acrylates of bisphenol A or bisphenol F, but are not limited to these, and various types can be used.

  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, hydroxypivalate ester neopentyl glycol di (meth) acrylate, 2,2- Bis [4- (meth) acryloyloxyethoxyethoxyphenyl] propane, 2,2-bis [4- (meth) acryloyloxyethoxyethoxycyclohexyl] propane, hydrogenated dicyclopentadienyl di (meth) acrylate, tricyclode Candimethanol di (meth) acrylate, 1,3-dioxane-2,5-diyldi (meth) acrylate [also known as dioxane glycol di (meth) acrylate], hydroxypivalaldehyde and trimethylol Di (meth) acrylate, tris (hydroxyethyl) of acetal compound [chemical name: 2- (2-hydroxy-1,1-dimethylethyl) -5-ethyl-5-hydroxymethyl-1,3-dioxane] with lopan ) 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 a representative one. Besides, poly (meth) acrylate of tri- or higher functional halogen-substituted polyol, alkylene oxide of glycerin Tri (meth) acrylate of adduct, tri (meth) acrylate of alkylene oxide adduct of trimethylolpropane, 1,1,1-tris [(meth) acryloyloxyethoxyethoxy] propane, tris (hydroxyethyl) isocyanurate tri Examples include (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 (eg, 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. Polybasic carboxylic acids or their anhydrides include (anhydrous) succinic acid, adipic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, (anhydrous) trimellitic acid, (anhydrous) pyromellitic acid, (anhydrous) Examples include phthalic acid, isophthalic acid, terephthalic acid, hexahydro (anhydride) phthalic acid, and the like.

  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 dehydration condensation reaction of (meth) acrylic acid, polybasic carboxylic acid or anhydride thereof, and polyol. Polybasic carboxylic acids or anhydrides used in the dehydration condensation reaction include (anhydrous) succinic acid, adipic acid, (anhydrous) maleic acid, (anhydrous) itaconic acid, (anhydrous) trimellitic acid, (anhydrous) pyrone Examples include merit acid, hexahydro (anhydride) phthalic acid, (anhydrous) phthalic acid, isophthalic acid, and terephthalic acid. 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.

  Among the above (meth) acrylate compounds, a compound having a structure represented by the following formula (XI) or (XII) is a cationically polymerizable compound, particularly an alicyclic epoxy compound, while the cured product gives a high elastic modulus. When combined with a compound, a protective layer having excellent adhesion to the polarizing film is obtained, which is preferable.

(In the formula, Q ₁ and Q ₂ each independently represent a (meth) acryloyloxy group or a (meth) acryloyloxyalkyl group, wherein the alkyl has 1 to 10 carbon atoms and Q ₃ is hydrogen or Represents a hydrocarbon group having 1 to 10 carbon atoms.)

In the above formula (XI) or (XII), when Q ₁ or Q ₂ is a (meth) acryloyloxyalkyl group, the alkyl may be linear or branched and has 1 to 10 carbon atoms. Generally, about 1 to 6 carbon atoms are sufficient. In the formula (XII), when Q ₃ is a hydrocarbon group, it may be linear or branched, and can typically be an alkyl group. In this case, it is generally sufficient for the alkyl group to have about 1 to 6 carbon atoms.

The compound represented by the formula (XI) is a di (meth) acrylate derivative of hydrogenated dicyclopentadiene or tricyclodecane dialkanol, and specific examples thereof are those exemplified above. Cyclopentadienyl di (meth) acrylate [in formula (XI), Q ₁ = Q ₂ = (meth) acryloyloxy group compound], tricyclodecane dimethanol di (meth) acrylate [in formula (XI), Q ₁ = Q ₂ = (meth) acryloyloxymethyl group compound] and the like.

Further, the compound represented by the formula (XII) is a di (meth) acrylate derivative of dioxane glycol or dioxane dialkanol, and specific examples thereof include those exemplified above, but 1,3-dioxane- 2,5-diyl di (meth) acrylate [also known as dioxane glycol di (meth) acrylate, compound of formula (XII), Q ₁ = Q ₂ = (meth) acryloyloxy group, Q ₃ = H], hydroxypival Acetal compound of aldehyde and trimethylolpropane [chemical name: 2- (2-hydroxy-1,1-dimethylethyl) -5-ethyl-5-hydroxymethyl-1,3-dioxane] di (meth) acrylate [ in the formula (XII), Q ₁ = (meth) acryloyloxy methyl group, Q ₂ = 2- (meth) acryloyl 1,1-dimethylethyl group, the compound of Q ₃ = ethyl group], and the like.

  In the curable resin composition used for forming the first protective layer, the (meth) acrylic compound is preferably contained in a proportion of 70% by weight or less in the active energy ray-curable compound. More preferably, it is contained at a rate of 40% by weight, and more preferably at a rate of 40-60% by weight. When the content of the (meth) acrylic compound exceeds 70% by weight, the adhesion with the polarizing film tends to be lowered.

  When this curable resin composition contains a radical polymerizable compound such as the (meth) acrylic compound as described above, it is preferable to incorporate a photo radical polymerization initiator. 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, Benzophenone initiators such as 4,4′-diaminobenzophenone; benzoin ether initiators such as benzoinpropyl ether and benzoin ethyl ether; thioxanthone initiators such as 4-isopropylthioxanthone; Fluoresce Down, camphor quinone, benzaldehyde, there is such as anthraquinone.

  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 the blending amount of the radical photopolymerization initiator is less than 0.5 parts by weight with respect to 100 parts by weight of the radical polymerizable compound, curing becomes insufficient, and mechanical strength and adhesion between the protective layer and the polarizing film are reduced. It tends to decrease. Moreover, when the compounding quantity of radical photopolymerization initiator exceeds 20 weight part with respect to 100 weight part of (meth) acrylic-type compounds, the hygroscopic property of hardened | cured material is high because the ionic substance in hardened | cured material increases. Thus, there is a possibility that the durability performance of the obtained polarizing plate is lowered.

  The curable resin composition can further contain a photosensitizer as necessary. By using a photosensitizer, the reactivity of the active energy ray-curable compound in cationic polymerization and / or radical polymerization is improved, and the mechanical strength of the protective layer and the adhesion between the protective layer and the polarizing film are improved. be able to. Examples of the photosensitizer include carbonyl compounds, organic sulfur compounds, persulfides, redox compounds, azo and diazo compounds, halogen compounds, and photoreductive dyes. Specific photosensitizers include, for example, benzoin derivatives such as benzoin methyl ether, benzoin isopropyl ether, α, α-dimethoxy-α-phenylacetophenone; benzophenone, 2,4-dichlorobenzophenone, o-benzoylbenzoic acid. Benzophenone derivatives such as methyl, 4,4′-bis (dimethylamino) benzophenone, 4,4′-bis (diethylamino) benzophenone; thioxanthone derivatives such as 2-chlorothioxanthone and 2-isopropylthioxanthone; 2-chloroanthraquinone, Anthraquinone derivatives such as 2-methylanthraquinone; acridone derivatives such as N-methylacridone and N-butylacridone; other, α, α-diethoxyacetophenone, benzyl, fluorenone, quinone Sandton, uranyl compounds, halogen compounds and the like can be mentioned. These may be used alone or in combination. The photosensitizer is preferably contained in the range of 0.1 to 20 parts by weight with respect to 100 parts by weight of the active energy ray-curable compound.

  Moreover, the curable resin composition may contain an antistatic agent for imparting antistatic performance to the polarizing plate. The antistatic agent is not particularly limited, and a known antistatic agent can be used. For example, cationic surfactants such as acyloylamidopropyldimethylhydroxyethylammonium nitrate, acyloylamidopropyltrimethylammonium sulfate, cetylmorpholium methosulfate; linear alkyl phosphate potassium salt, polyoxyethylene alkyl phosphate Anionic surfactants such as potassium salts and alkane sulfonates; nonionic interfaces such as N, N-bis (hydroxyethyl) -N-alkylamines, their fatty acid ester derivatives, and polyhydric alcohol fatty acid partial esters An activator or the like can be used. The blending ratio of these antistatic agents is appropriately determined according to the desired characteristics, but is usually about 0.1 to 20 parts by weight with respect to 100 parts by weight of the active energy ray-curable compound.

  In the curable resin composition, a known polymer additive usually used for a polymer material can be added. Examples include primary antioxidants such as phenols and amines, sulfur secondary antioxidants, hindered amine light stabilizers (HALS), benzophenone, benzotriazole, and benzoate UV absorbers. It is done.

  Silica fine particles may be added to the curable resin composition. By adding silica fine particles, the hardness and mechanical strength of the protective layer obtained can be further improved. Silica fine particles can be blended in the curable resin composition, for example, as a liquid dispersed in an organic solvent.

  The silica fine particles may have a reactive functional group such as a hydroxyl group, an epoxy group, a (meth) acryloyl group, or a vinyl group on the surface thereof. The particle size of the silica fine particles is usually 100 nm or less, preferably about 5 to 50 nm. When the particle diameter of the fine particles exceeds 100 nm, an optically transparent protective layer tends to be not obtained.

  In the case of using silica fine particles dispersed in an organic solvent, the silica concentration is not particularly limited, and a commercially available product, for example, about 20 to 40% by weight can be used.

  Examples of silica fine particles dispersed in an organic solvent available as a commercial product include, for example, “methanol silica sol” (manufactured by Nissan Chemical Industries, Ltd., silica particle size of 10 to 15 nm, solid content of 30 wt. %), “MA-ST-M” (manufactured by Nissan Chemical Industries, Ltd., silica particle size 20 to 25 nm, solid content 40% by weight), “OSCAL 1132” (manufactured by Catalyst Chemical Industry Co., Ltd., silica particle size 10) "OSCAL 1232" (catalyst chemical industry Co., Ltd., silica particle size 10 to 20 nm, solid content 30 to 31 wt%); organic solvent, organic solvent is ethyl alcohol “OSCAL 1332” (produced by Catalytic Chemical Industry Co., Ltd., silica particle size 10 to 20 nm, solid content 30 to 31 wt%); “IPA-ST” which is sopropyl alcohol (manufactured by Nissan Chemical Industries, Ltd., silica particle size 10 to 15 nm, solid content 30% by weight), “OSCAL 1432” (manufactured by Catalyst Chemical Industries, Ltd., silica particle size 10 ˜20 nm, solid content 30-31 wt%); “NBA-ST” (Nissan Chemical Industry Co., Ltd., silica particle size 10-15 nm, solid content 20 wt%), where the organic solvent is n-butyl alcohol, “ "OSCAL 1532" (manufactured by Catalytic Chemical Industry Co., Ltd., silica particle size 10 to 20 nm, solid content 30 to 31 wt%); "EG-ST" (Nissan Chemical Industry Co., Ltd., silica, whose organic solvent is ethylene glycol) “OSCAL 1632” (catalyst chemical industry Co., Ltd., silica particle size 10 to 20 nm, solid content 3) whose organic solvent is ethyl cellosolve “NPC-ST” (manufactured by Nissan Chemical Industries, Ltd., silica particle size 10 to 15 nm, solid content 30% by weight); organic solvent is dimethyl “DMAC-ST” (manufactured by Nissan Chemical Industries, silica particle size 10-15 nm, solid content 20% by weight), “DMAC-ST-ZL” (manufactured by Nissan Chemical Industries, silica particle size) "XBA-ST" (Nissan Chemical Industry Co., Ltd., silica particle size 10-15 nm, solid content 30% by weight, organic solvent is a mixture of xylene and n-butyl alcohol) "MIBK-ST" (manufactured by Nissan Chemical Industries, silica particle size 10-15 nm, solid content 30% by weight); the organic solvent is methyl ethyl “MEK-ST” (manufactured by Nissan Chemical Industries, silica particle size 10-15 nm, solid content 30% by weight), “SP-1120” (manufactured by Konishi Chemical Industries, silica particle size 15- 20 nm, solid content 5 to 10% by weight), “SP-6120” (manufactured by Konishi Chemical Industry Co., Ltd., silica particle size 15 to 20 nm, solid content 5 to 10% by weight) and the like. Two or more kinds can be suitably used. In addition, “Snowtex 20” whose dispersion medium is water (Nissan Chemical Industry Co., Ltd., silica particle size 10-20 nm) “Snowtex C” (Nissan Chemical Industry Co., Ltd., silica particle size 10-20 nm) ) Etc. can also be used.

  The silica fine particles are preferably added in an amount of 5 to 250 parts by weight, more preferably 10 to 100 parts by weight, based on 100 parts by weight of the active energy ray-curable compound contained in the curable resin composition. When the addition amount of the silica fine particles is less than 5 parts by weight with respect to 100 parts by weight of the active energy ray-curable compound, the improvement of the hardness of the protective layer by the addition of the silica fine particles may not be sufficient. On the other hand, when the addition amount of silica fine particles exceeds 250 parts by weight with respect to 100 parts by weight of the active energy ray-curable compound, the adhesion between the polarizing film and the protective layer may be lowered. Moreover, when the addition amount of a silica fine particle exceeds 250 weight part, the dispersion stability of the fine particle in a curable resin composition may fall, or the viscosity of a curable resin composition may rise excessively.

  Furthermore, the curable resin composition may contain a solvent as necessary. The solvent is appropriately selected depending on the solubility of the components constituting the curable resin composition. 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; halogens such as methylene chloride and chloroform Hydrocarbons and the like. The mixing ratio of the solvent is appropriately determined from the viewpoint of the viscosity of the desired curable resin composition in consideration of processability such as film formability.

  Moreover, the curable resin composition can contain a leveling agent as needed. When the curable resin composition is applied onto a polarizing film or a substrate, if the wettability to the polarizing film or the substrate is poor or the surface property of the cured product of the curable resin composition is poor, leveling is performed. They can be improved by adding agents. As the leveling agent, various compounds such as silicone-based, fluorine-based, polyether-based, acrylic acid copolymer-based and titanate-based compounds can be used. These leveling agents may be used alone or in combination of two or more.

  The leveling agent is preferably added in an amount of 0.01 to 1 part by weight, more preferably 0.1 to 0.7 part by weight based on 100 parts by weight of the active energy ray-curable compound contained in the curable resin composition. Part by weight, more preferably 0.2 to 0.5 part by weight. When the leveling agent is added in an amount of less than 0.01 part by weight based on 100 parts by weight of the active energy ray-curable compound, improvement of wettability and surface property may not be sufficient. Moreover, when the addition amount of a leveling agent exceeds 1 weight part with respect to 100 weight part of active energy ray hardening compounds, the adhesiveness of a polarizing film and a protective layer may fall.

  The thickness of the first protective layer formed from the curable resin composition containing the active energy ray-curable compound as described above is preferably 0.1 to 10 μm, and more preferably 1 to 5 μm. When the thickness of the first protective layer is less than 0.1 μm, the durability is not sufficient, and when it exceeds 10 μm, the effect of reducing the thickness and weight of the polarizing plate is reduced. A method for forming the first protective layer using the curable resin composition will be described later.

(2) Second protective layer A second protective layer made of a thermoplastic resin film is provided on the surface of the polarizing film opposite to the side on which the first protective layer is laminated via an adhesive layer. Laminated. As the second protective layer in the polarizing plate of the present invention, for example, cellulose acetate resin, cycloolefin resin, polyolefin resin, acrylic resin, polyimide resin, polycarbonate resin, polyester resin, etc. A thermoplastic resin film composed of an appropriate material widely used as a material for forming the protective layer can be used without any particular limitation. From the viewpoint of mass productivity and adhesiveness, among them, it is preferable to use a cellulose acetate-based resin film or a cycloolefin-based resin film as the second protective layer. Moreover, it is more preferable to use a cellulose acetate-based resin film as the second protective layer from the viewpoint of easy provision of the surface treatment layer and optical characteristics.

  The cycloolefin resin that can be suitably used for the second protective layer in the present invention is, for example, a thermoplastic resin having a monomer unit composed of a cyclic olefin (cycloolefin) such as norbornene and a polycyclic norbornene monomer. (Also called a thermoplastic cycloolefin resin). This cycloolefin-based resin may be a hydrogenated product of a ring-opening polymer of the above-mentioned cycloolefin, a ring-opening copolymer using two or more kinds of cycloolefin, cycloolefin and chain olefin, vinyl group, etc. It may be an addition polymer with an aromatic compound having Those having a polar group introduced are also effective.

  When the second protective layer is formed using a copolymer of a cycloolefin, a chain olefin, and an aromatic compound having a vinyl group, examples of the chain olefin include ethylene and propylene. Examples of the aromatic compound include styrene, α-methylstyrene, and nuclear alkyl-substituted styrene. In such a copolymer, the monomer unit composed of cycloolefin may be 50 mol% or less (preferably 15 to 50 mol%). In particular, when the second protective layer is formed using a terpolymer of cycloolefin, chain olefin, and aromatic compound having a vinyl group, the monomer unit composed of cycloolefin is compared as described above. Less amount. In such a terpolymer, the monomer unit composed of a chain olefin is usually 5 to 80 mol%, and the monomer unit composed of an aromatic compound having a vinyl group is usually 5 to 80 mol%.

  Cycloolefin-based resins are commercially available as appropriate, for example, “Topas” (manufactured by Ticona), “Arton” (manufactured by JSR Corporation), “ZEONOR” (manufactured by Nippon Zeon Co., Ltd.), “ZEONEX ( “ZEONEX” ”(manufactured by Nippon Zeon Co., Ltd.),“ Apel ”(manufactured by Mitsui Chemicals, Inc.) (all are trade names) and the like can be suitably used. When such a cycloolefin-based resin is formed into a film, a known method such as a solvent casting method or a melt extrusion method is appropriately used. In addition, for example, “Essina” (manufactured by Sekisui Chemical Co., Ltd.), “SCA40” (manufactured by Sekisui Chemical Co., Ltd.), “Zeonor Film” (manufactured by Optes Co., Ltd.), etc. A commercial product of a resin film may be used as the second protective layer.

  The cycloolefin resin film used as the second protective layer may be uniaxially stretched or biaxially stretched. In this case, the draw ratio is usually 1.1 to 5 times, preferably 1.1 to 3 times.

  In addition, the cellulose acetate-based resin film that can be suitably used as the second protective layer in the present invention is a film made of a cellulose part or a complete acetate ester, and examples thereof include a triacetyl cellulose film and a diacetyl cellulose film. It is done.

  As the cellulose acetate-based resin constituting such a cellulose acetate-based resin film, appropriate commercially available products such as “Fujitac TD80” (manufactured by Fuji Photo Film Co., Ltd.), “Fujitac TD80UF” (manufactured by Fuji Photo Film Co., Ltd.) ), “Fujitac TD80UZ” (manufactured by Fuji Photo Film Co., Ltd.), “KC8UX2M” (manufactured by Konica Minolta Opto Co., Ltd.), “KC8UY” (manufactured by Konica Minolta Opto Co., Ltd.), etc. (all are trade names) A film made of cellulose acetate resin can be suitably used.

  The second protective layer used in the polarizing plate of the present invention preferably has a small thickness, but if it is too thin, the strength tends to be low, and the processability tends to be poor. If it is too thick, the transparency is low. Or the weight of the polarizing plate tends to increase. From such a viewpoint, the thickness of the second protective layer in the polarizing plate of the present invention is usually 5 to 200 μm, preferably 10 to 150 μm, more preferably in the case of a protective layer composed of a cycloolefin-based resin. In the case of a protective layer made of a cellulose acetate resin, the thickness is usually 20 to 200 μm, preferably 30 to 150 μm, more preferably 40 to 100 μm.

  The second protective layer in the polarizing plate of the present invention was subjected to surface treatment such as antiglare treatment, hard coat treatment, antistatic treatment, antireflection treatment on the surface opposite to the surface attached to the polarizing film. It may be a thing. Moreover, the coating layer which consists of a liquid crystalline compound, its high molecular weight compound, etc. may be formed in the surface on the opposite side to the surface stuck to the polarizing film of a 2nd protective layer.

  The polarizing film and the second protective layer (thermoplastic resin film) are attached using an adhesive as described in detail below. In adhering these films using an adhesive, plasma treatment, corona treatment, and ultraviolet irradiation are applied to the adhesion surface of the polarizing film and / or the second protective layer to be bonded to the polarizing film in order to improve adhesion. Surface treatment such as treatment, flame (flame) treatment, and saponification treatment may be appropriately performed. Examples of the saponification treatment include a method of immersing in an aqueous alkali solution such as sodium hydroxide or potassium hydroxide. Hereinafter, the adhesive used for sticking the polarizing film and the second protective layer will be described.

(Adhesive layer)
The adhesive layer with which the polarizing plate of this invention is provided consists of the adhesive agent (adhesive composition) used for sticking of a polarizing film and a 2nd protective layer, or its hardened | cured material. Such an adhesive composition in the present invention is not particularly limited, but a curable resin composition containing an active energy ray-curable compound, an adhesive component dissolved in water, or an adhesive component in water. Examples thereof include a dispersed aqueous adhesive. In this, since a drying process is unnecessary, it is preferable to use the curable resin composition containing an active energy ray curable compound.

  Examples of the curable resin composition as the adhesive composition include those similar to the curable resin composition forming the first protective layer described above. A curable resin composition that forms the first protective layer and an active energy ray-curable compound contained therein, a curable resin composition that is an adhesive composition, an active energy ray-curable compound contained therein, and the like May be the same or different.

  Examples of the water-based adhesive in which the adhesive component is dissolved in water or the adhesive component in which the adhesive component is dispersed in water include an adhesive composition using a polyvinyl alcohol resin or a urethane resin as a main component.

  When using a polyvinyl alcohol-based resin as the main component of the water-based adhesive, the polyvinyl alcohol-based resin is not only partially saponified polyvinyl alcohol or fully saponified polyvinyl alcohol, but also carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, It may be a modified polyvinyl alcohol resin such as methylol group-modified polyvinyl alcohol or amino group-modified polyvinyl alcohol. When a polyvinyl alcohol resin is used as the adhesive component, the adhesive is often prepared as an aqueous solution of a polyvinyl alcohol resin. The density | concentration of the polyvinyl alcohol-type resin in an adhesive agent is about 1-10 weight part normally with respect to 100 weight part of water, Preferably it is 1-5 weight part.

  In order to improve the adhesiveness, it is preferable to add a curable component such as glyoxal or a water-soluble epoxy resin or a crosslinking agent to the adhesive containing a polyvinyl alcohol resin as a main component. Examples of water-soluble epoxy resins include polyamide polyamines obtained by reacting a polyalkylene polyamine such as diethylenetriamine or triethylenetetramine with a dicarboxylic acid such as adipic acid and epichlorohydrin. An epoxy resin can be mentioned. Commercially available products of such polyamide polyamine epoxy resins include “Smiles Resin 650” and “Smiles Resin 675” sold by Sumika Chemtex Co., Ltd., and “WS-525” sold by Japan PMC Co., Ltd. Etc., and these can be preferably used. The addition amount of these curable components or crosslinking agents is usually 1 to 100 parts by weight, preferably 1 to 50 parts by weight with respect to 100 parts by weight of the polyvinyl alcohol resin. If the amount added is small, the effect of improving the adhesiveness is reduced, while if the amount added is large, the adhesive layer tends to be brittle.

  When a urethane resin is used as the main component of the water-based adhesive, examples of a suitable adhesive composition include a mixture of a polyester ionomer-type urethane resin and a compound having a glycidyloxy group. The polyester-based ionomer type urethane resin here is a urethane resin having a polyester skeleton, into which a small amount of an ionic component (hydrophilic component) is introduced. Such an ionomer-type urethane resin is suitable as a water-based adhesive because it is emulsified directly in water without using an emulsifier to form an emulsion. Polyester ionomer urethane resins are known per se. For example, Japanese Patent Application Laid-Open No. 7-97504 discloses a polyester ionomer type urethane resin as an example of a polymer dispersant for dispersing a phenolic resin in an aqueous medium, and Japanese Patent Application Laid-Open No. 2005-070140. JP-A-2005-181817 discloses a mode in which a cycloolefin resin film is bonded to a polarizing film made of a polyvinyl alcohol resin using a mixture of a polyester ionomer type urethane resin and a compound having a glycidyloxy group as an adhesive. It is shown.

  The thickness of the adhesive layer of the present invention is preferably 20 μm or less, more preferably 10 μm or less, and further preferably 5 μm or less. When the thickness of the adhesive layer is 20 μm or less, there is little risk of impairing the appearance of the polarizing plate.

(Adhesive layer)
Moreover, the polarizing plate of this invention may have an adhesive layer in the surface on the opposite side to the polarizing film side in the 1st protective layer. Such an adhesive layer can be used, for example, for bonding with a liquid crystal cell. When a polarizing plate and a liquid crystal cell are bonded using this pressure-sensitive adhesive layer to form a liquid crystal display device, the protective layer interposed between the polarizing film and the liquid crystal cell is formed from a cured product of the curable resin composition. Thus, since the first protective layer has in-plane and film thickness direction retardations of substantially zero, light leakage during black display can be effectively prevented.

  For example, the pressure-sensitive adhesive layer is formed by dissolving or dispersing a pressure-sensitive adhesive composition such as a base polymer as a pressure-sensitive adhesive component in an organic solvent such as toluene or ethyl acetate to prepare a 10 to 40% by weight solution. A method of forming a pressure-sensitive adhesive layer by coating directly on the first protective layer, or a pressure-sensitive adhesive by previously forming a pressure-sensitive adhesive layer on a protective film and transferring it to the first protective layer This can be done by a method of forming a layer. Although the thickness of an adhesive layer is determined according to the adhesive force etc., it is the range of 1-50 micrometers normally.

  Examples of the base polymer include acrylic polymers, silicone polymers, polyesters, polyurethanes, polyethers, and the like. Among them, like acrylic pressure-sensitive adhesives based on acrylic polymers, it has excellent optical transparency, moderate wettability and cohesion, and adhesion to the first protective layer and liquid crystal cell. In addition, it is preferable to select and use one that has excellent weather resistance, heat resistance, and the like and does not cause peeling problems such as floating and peeling under the conditions of heating and humidification.

  Examples of the acrylic base polymer contained in the acrylic pressure-sensitive adhesive include alkyl esters of acrylic acid having an alkyl group having 20 or less carbon atoms such as a methyl group, an ethyl group, and a butyl group, and (meth) acrylic acid or (meta ) An acrylic copolymer with a functional group-containing acrylic monomer such as hydroxyethyl acrylate. The glass transition temperature of the acrylic copolymer is preferably 25 ° C. or lower, more preferably 0 ° C. or lower. The weight average molecular weight of the acrylic copolymer is preferably 100,000 or more.

  If necessary, the adhesive layer may contain fillers made of glass fiber, glass beads, resin beads, inorganic powders such as metal powder, pigments, colorants, antioxidants, UV absorbers, etc. Good. Examples of ultraviolet absorbers include salicylic acid ester compounds, benzophenone compounds, benzotriazole compounds, cyanoacrylate compounds, nickel complex compounds, and the like.

<Production method of polarizing plate>
The polarizing plate of this invention can be manufactured through the following process. The order of the following steps (i) and (ii) is not particularly limited, and can be performed simultaneously.
(I) a step of forming the first protective layer on one surface of the polarizing film, and (ii) a step of bonding the second protective layer to the other surface of the polarizing film via an adhesive. .

  In the above step (i), examples of the method for forming the first protective layer include the following methods. First, a curable resin composition containing an active energy ray-cured product that forms a first protective layer on a substrate is applied, dried as necessary, and a curable resin composition on the surface of the substrate. The coating layer is provided (coating layer forming step). Next, the polarizing film and the coating layer are bonded so that the coating surface becomes a bonding surface (application layer bonding step). Next, a laminate comprising this polarizing film / coating layer / substrate (when step (ii) is performed before step (i), this laminate further comprises an adhesive layer and a second protective layer). For example, from the substrate side by irradiating or heating active energy rays such as visible light, ultraviolet rays, X-rays, electron beams, etc., to cure the coating layer made of the curable resin composition. One protective layer is formed (curing step). Finally, the base material on the first protective layer is removed (base material removal step). Here, as a base material, a metal belt, a glass plate, a polyethylene terephthalate film, a polycarbonate film, a triacetyl cellulose film, a norbornene film, a polyester film, a polystyrene film etc. are mentioned, for example. The surface on which the curable resin composition of the base material is applied may be subjected to a peeling treatment, for example.

  Moreover, as another method of the said process (i), the curable resin composition containing the active energy ray-curable compound which forms a 1st protective layer is directly applied to a polarizing film, and an active energy ray is irradiated. Or the method of hardening the application layer which consists of curable resin compositions by heating, and forming a 1st protective layer is also mentioned. In this case, a base material can be dispensed with.

  In the said process (ii), the following methods are mentioned as a method of bonding a 2nd protective layer. First, the adhesive composition is applied to the second protective layer (thermoplastic resin film) and dried as necessary. Subsequently, a polarizing film and a 2nd protective layer are bonded so that this coating surface may become a bonding surface (film bonding process). Next, a laminate comprising this polarizing film / adhesive / second protective layer (when step (i) is carried out before step (ii), this laminate is further provided with a second protective layer (or The coating layer of the curable resin composition) and the substrate are dried, or the laminate is irradiated or heated with active energy rays such as visible light, ultraviolet rays, X-rays, and electron beams. The adhesive composition is cured to adhere the polarizing film and the second protective layer, and dried as necessary. When a curable resin composition containing an active energy ray-curable compound is used as the adhesive composition, the drying step can be omitted, and thus the production efficiency can be improved.

  In addition, the adhesive composition is directly applied to the polarizing film and bonded to the second protective layer, and then dried, or the adhesive composition is cured by irradiation or heating with active energy rays. The polarizing film and the 2nd protective layer are made to adhere, and the method of making it dry as needed is also mentioned.

  The first protective layer and the second protective layer may be formed at the same time. For example, a curable adhesive composition (such as a curable resin composition containing an active energy ray-curable compound, a water-based adhesive containing a curable component or a crosslinking agent) is used as the adhesive, and the second protective layer After preparing a laminate consisting of / adhesive / polarizing film / coating layer / substrate, the adhesive and coating layer are simultaneously cured by irradiating or heating the laminate with, for example, active energy rays. Thus, a polarizing plate can be obtained. According to this method, since the curing process is only required once, the production efficiency can be further improved.

  In the present invention, the coating method of the curable resin composition and the adhesive composition containing the active energy ray-curable compound that forms the first protective layer is not particularly limited. For example, a doctor blade, a wire bar, Various coating methods such as die coater, comma coater and gravure coater can be used. Moreover, after dripping the curable resin composition or adhesive composition containing the active energy ray-curable compound between the polarizing film and the second protective layer or the substrate, it is uniformly pressed by a roll or the like. In the method of spreading the film, metal, rubber or the like can be used as the material of the roll. Moreover, what dropped the curable resin composition or adhesive composition containing the said active energy ray hardening compound between a polarizing film and a 2nd protective layer or a base material between a roll and a roll. In the method of passing and pressurizing and spreading, these rolls may be made of the same material or different materials.

When curing the curable resin composition and / or adhesive composition containing the active energy ray-curable compound that forms the first protective layer by irradiation with active energy rays, the light source used is not particularly limited. However, for example, a low-pressure mercury lamp, a medium-pressure mercury lamp, a high-pressure mercury lamp, an ultrahigh-pressure mercury lamp, a chemical lamp, a black light lamp, a microwave excitation mercury lamp, a metal halide lamp or the like having a light emission distribution at a wavelength of 400 nm or less can be used. The light irradiation intensity to the curable resin composition or the adhesive composition may vary depending on the composition, but the irradiation intensity in the wavelength region effective for activation of the photo radical polymerization initiator and / or the photo cationic polymerization initiator. Is preferably 10 to 2500 mW / cm ² . When the light irradiation intensity to the curable resin composition is less than 10 mW / cm ² , the reaction time becomes too long, and when it exceeds 2500 mW / cm ² , the heat radiated from the lamp and the curable resin composition or adhesive The heat generated during the polymerization of the composition may cause yellowing of the curable resin composition or adhesive composition and deterioration of the polarizing film. The light irradiation time to the curable resin composition or the adhesive composition is controlled for each composition and is not particularly limited, but the integrated light amount expressed as the product of the irradiation intensity and the irradiation time. Is preferably set to be 10 to 2500 mJ / cm ² . When the integrated light amount to the curable resin composition or the adhesive composition is less than 10 mJ / cm ² , the generation of active species derived from the polymerization initiator is not sufficient, and the resulting protective layer and adhesive layer are not cured. It may be sufficient. On the other hand, if the integrated light quantity exceeds 2500 mJ / cm ² , the irradiation time becomes very long, which is disadvantageous for improving productivity. In addition, it is preferable that irradiation of an active energy ray is performed in the range in which various performances, such as the polarization degree of a polarizing film and a transmittance | permeability, do not fall.

<Liquid crystal display device>
The liquid crystal display device of the present invention includes the polarizing plate of the present invention, and more specifically, includes a liquid crystal cell and a pair of polarizing plates disposed on both surfaces of the liquid crystal cell. Or it is a liquid crystal display device whose both polarizing plates are the polarizing plates of the said invention. Here, in the liquid crystal display device of the present invention, the polarizing plate of the present invention is bonded to the liquid crystal cell so that the first protective layer is on the liquid crystal cell side. That is, when the said adhesive layer is provided on a 1st protective layer, it is bonded to a liquid crystal cell by the adhesive layer side. In the liquid crystal display device of the present invention having such a configuration, light leakage during black display is effectively prevented, and a reduction in thickness and weight is achieved.

  The liquid crystal cell used in the liquid crystal display device of the present invention may be in any mode. However, when an IPS mode liquid crystal cell operating in the transverse electric field mode is used, the light leakage prevention effect particularly at the time of remarkable black display is achieved. Can be obtained.

  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, “parts” and “%” 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 2400 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 the weight ratio of iodine / potassium iodide / water was 0.02 / 2. / 100 aqueous solution at 30 ° C. Then, it was immersed at 56.5 ° C. in an aqueous solution having a potassium iodide / boric acid / water weight ratio of 12/5/100. Subsequently, after washing with pure water at 8 ° C., it was dried at 65 ° C. to obtain a polarizing film in which iodine was adsorbed and oriented on polyvinyl alcohol. Stretching was mainly performed in the iodine staining and boric acid treatment steps, and the total stretching ratio was 5.3 times.

(Production Example 2: Preparation of curable resin composition I)
First, the following components were mixed to obtain a curable resin composition I.

3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (Daicel Chemical Industries, Celoxide 2021P) 35 parts Bis (3-ethyl-3-oxetanylmethyl) ether (Toagosei Co., Ltd., Aron) Oxetane OXT-221) 15 parts Diacrylate of acetal compound of hydroxypivalaldehyde and trimethylolpropane (Shin-Nakamura Chemical Co., Ltd., A-DOG) 50 parts 2-hydroxy-2-methyl-1-phenylpropane -1-one (Ciba Specialty Chemicals, DAROCURE 1173, photo radical polymerization initiator)
2.5 parts 4,4′-bis [diphenylsulfonio] diphenyl sulfide Bishexafluorophosphate-based photocationic polymerization initiator (UVACURE 1590, manufactured by Daicel-Cytec Co., Ltd.) 2.5 parts Silicone leveling agent ) Toray Dow Corning Co., Ltd., SH710)
0.2 part In addition, said A-DOG (diacrylate of the acetal compound of a hydroxypivalaldehyde and a trimethylol propane) is a compound which has a structure of following Formula.

(Production Example 3: Preparation of Curable Resin Composition II)
The following components were mixed to obtain a curable resin composition II.

3,4-epoxycyclohexylmethyl-3,4-epoxycyclohexanecarboxylate (Daicel Chemical Industries, Celoxide 2021P) 75 parts Bis (3-ethyl-3-oxetanylmethyl) ether (Toagosei Co., Ltd., Aron) Oxetane OXT-221) 25 parts 4,4′-bis [diphenylsulfonio] diphenyl sulfide Bishexafluorophosphate photocationic polymerization initiator (Daicel Cytec Co., Ltd. UVACURE 1590) 5 parts Silicone leveling agent (Toray -Dow Corning Co., Ltd., SH710)
0.2 parts

(Production Example 4: Preparation of polyvinyl alcohol-based adhesive)
The following components were mixed to obtain a polyvinyl alcohol-based adhesive.
Pure water 100 parts Carboxyl group-modified polyvinyl alcohol (“Kuraray Poval KL318” manufactured by Kuraray Co., Ltd.) 1.8 parts Water-soluble polyamide epoxy resin (Sumirez resin 650 manufactured by Sumika Chemtex Co., Ltd. (solid content concentration) 30% aqueous solution)) 0.9 parts

(Production Example 5: Production of polarizing plate A)
One side of the polarizing film produced in Production Example 1 was coated with the polyvinyl alcohol-based adhesive obtained in Production Example 4 and subjected to saponification treatment (Konica Minolta Opto Co., Ltd.). ), KC8UY, thickness 80 μm). This was dried at 60 ° C. for 6 minutes to produce a polarizing plate A having a protective layer on one side.

<Example 1>
A curable resin obtained in Production Example 2 on one side of a polyethylene terephthalate (PET) film (Ester film E5100, manufactured by Toyobo Co., Ltd.) using a coating machine (manufactured by Daiichi Rika Co., Ltd., bar coater). Composition I was applied. Further, a corona discharge treatment was applied to one side of a protective layer (Konica Minolta Opto Co., Ltd., KC8UX, thickness 80 μm) made of a triacetyl cellulose film that had not been saponified, and curable resin was similarly applied to that side. Composition II was applied. Under the present circumstances, since the film thickness of the coating layer when a curable resin composition was applied changes with viscosity, the film thickness was adjusted by changing the number of the bar coater's number line. Next, the polarizing film produced in Production Example 1 has a PET film having a coating layer of the curable resin composition I on one surface and a coating layer of the curable resin composition II on the other surface. The protective layer was bonded using a bonding apparatus (manufactured by Fuji Plastic Co., Ltd., LPA3301) so that each coating layer side would be a bonding surface with the polarizing film.

This bonded product is irradiated with ultraviolet rays from the PET film side with an integrated light amount of 1500 mJ / cm ² by a D bulb manufactured by Fusion UV Systems, and coated with curable resin compositions I and II disposed on both sides of the polarizing film. The layer was cured. Thereafter, the PET film is peeled off, and a transparent first protective layer (cured product of the curable resin composition I) is provided on one side of the polarizing film, and a transparent second protective layer (tri-layer) is provided on the other side. A polarizing plate provided with an acetylcellulose film was prepared. In addition, it was 116 micrometers when the thickness of this polarizing plate was measured using the film thickness measuring device (made by Nikon Corporation, ZC-101). The thickness of the first protective layer was 4 μm.

<Example 2>
A curable resin obtained in Production Example 2 on one side of a polyethylene terephthalate (PET) film (Ester film E5100, manufactured by Toyobo Co., Ltd.) using a coating machine (manufactured by Daiichi Rika Co., Ltd., bar coater). Composition I was applied. Under the present circumstances, since the film thickness of the coating layer when a curable resin composition was applied changes with viscosity, the film thickness was adjusted by changing the number of the bar coater's number line. Next, a PET film having a coating layer of the curable resin composition I on the side opposite to the surface on which the protective layer of the polarizing plate A produced in Production Example 5 is bonded, and the coating layer side is a polarizing film Bonding was performed using a bonding device (manufactured by Fuji Plastic Co., Ltd., LPA3301) so as to be a bonding surface.

This bonded product is irradiated with ultraviolet rays from the PET film side with an integrated light quantity of 1500 mJ / cm ² using a D bulb manufactured by Fusion UV Systems, and a coating layer of the active energy ray-curable resin composition I disposed on the polarizing film. Was cured. Thereafter, the PET film was peeled off to produce a polarizing plate. The thickness of this polarizing plate was 114 μm. Moreover, the thickness of the 1st protective layer (hardened | cured material of the curable resin composition I) was 4 micrometers.

<Comparative Example 1>
The polarizing plate A produced in Production Example 5 was used. The thickness of the polarizing plate A was 110 μm.

<Comparative example 2>
A protective layer (Konica Minolta Opto (Konica Minolta Opto) (coated with the polyvinyl alcohol adhesive obtained in Production Example 4 on both surfaces of the polarizing film produced in Production Example 1 and saponified on one surface) Co., Ltd., KC8UY, thickness 80 μm), protective layer (manufactured by Konica Minolta Opto Co., Ltd.) having an in-plane retardation R _e and a retardation R _{th in the} film thickness direction of almost zero on the other side. KC4UEW, thickness 40 μm) was bonded. This was dried at 60 ° C. for 6 minutes to produce a polarizing plate. The thickness of this polarizing plate was 150 μm.

<Evaluation test>
(1) Adhesive durability test After providing an adhesive layer to the polarizing plates of Examples 1-2 and Comparative Examples 1-2 above by the following method, the durability of the polarizing plate was evaluated according to the following test method. .

[Formation of adhesive layer]
A pressure-sensitive adhesive solution containing a copolymer of butyl acrylate and acrylic acid, a urethane acrylate oligomer, an isocyanate-based crosslinking agent, and an organic solvent was placed on the first protective layer of the polarizing plates of Examples 1 and 2 as Comparative Example 1. The pressure-sensitive adhesive layer was formed on each polarizing plate by coating and drying on the polarizing film of the polarizing plate and the protective layer (KC4UEW) made of triacetyl cellulose of the polarizing plate of Comparative Example 2.

[Test method]
After sticking the polarizing plate with the pressure-sensitive adhesive layer to glass through the pressure-sensitive adhesive layer, a heat resistance test is performed for 300 hours under dry conditions at a temperature of 80 ° C., and the polarizing plate after the test is visually observed. did. The results are shown in Table 1. The evaluation criteria are as follows.

○: Almost no change in appearance such as floating, peeling or foaming.
Δ: Appearance changes such as floating, peeling and foaming are slightly noticeable.

X: Remarkable changes in appearance such as floating, peeling, foaming, etc.
(2) Measurement of Retardation of Protective Layer Protection of the first protective layer (cured product of curable resin composition I) used in the polarizing plates of Examples 1 and 2 and the polarizing plate of Comparative Example 2 comprising triacetyl cellulose. In-plane retardation R _e and thickness direction retardation R _th of the layer (KC4UEW) were measured by the following methods. The results are shown in Table 1. In addition, the measurement result of the retardation of the 1st protective layer used with the polarizing plate of Example 1 and 2 formed the cured | curing material of the curable resin composition I on a PET film like the above, and PET film It is about a cured product film (thickness 4 μm) obtained by peeling.

[In-plane retardation R _e ]
Using Oji Scientific Instruments Co., Ltd. measuring instrument "KOBRA-21ADH", by the rotating analyzer method with monochromatic light of wavelength 559 nm, measurement of retardation R _e in the plane.

[Retardation in the film thickness direction R _th ]
Using the same “KOBRA-21ADH” as above, the retardation R _th in the film thickness direction was measured with monochromatic light having a wavelength of 559 nm. The measurement procedure using this measuring machine is as follows. Using the in-plane retardation R _e , the retardation R ₄₀ measured by tilting the slow axis by 40 degrees with the slow axis as the tilt axis, the film thickness d, and the average refractive index n ₀ of the film, the following formulas (3) to (3) seek n _x, n _y and n _z numerically from 5), by substituting them into the formula (2), calculates the retardation R _th in the thickness direction.

_{R e = (n x -n y} ) × d (3)
R ₄₀ = (n _x −ny _y ) × d / cos (φ) (4)
(n _x + _ny + _nz ) / 3 = n ₀ (5)
here,
φ = sin ⁻¹ [sin (40 °) / n ₀ ]
n _y ′ = _ny × n ₀ / [ _ny ² × sin ² (φ) + _nz ² × cos ² (φ)] ^1/2

  It should be understood that the embodiments and examples disclosed herein are illustrative and non-restrictive in every respect. The scope of the present invention is defined by the terms of the claims, rather than the description above, and is intended to include any modifications within the scope and meaning equivalent to the terms of the claims.

It is a cross-sectional schematic diagram which shows the structural example of the liquid crystal display device of an IPS mode. In order to explain the principle of the IPS mode, it is a schematic perspective view showing an example of normally black, where (A) shows a state when no voltage is applied, and (B) shows a state when a voltage is applied. It is a schematic sectional drawing which shows a preferable example of the polarizing plate which concerns on this invention.

Explanation of symbols

  10 liquid crystal cell, 11, 12 cell substrate, 13 electrode, 14 liquid crystal layer, 15 liquid crystal molecule, 16 linearly polarized light incident on the liquid crystal cell, 17 linearly polarized light after passing through the liquid crystal cell, 17 'elliptical polarized light after passing through the liquid crystal cell, 18 Electric field, 20 Front-side polarizing plate, 22 Front-side polarizing plate transmission axis, 30 Back-side polarizing plate, 32 Back-side polarizing plate transmission axis, 40 Backlight, 50 Polarizing plate, 51 Polarizing film, 52 First protective layer 53 Second protective layer, 54 Adhesive layer, 55 Adhesive layer.

Claims (15)

A polarizing film having a dichroic dye adsorbed and oriented on a polyvinyl alcohol resin;
1st which consists of hardened | cured material of the curable resin composition containing the active energy ray-curable compound containing the epoxy-type compound which has at least 1 epoxy group in the molecule | numerator laminated | stacked on the one surface of the said polarizing film. A protective layer;
A second protective layer made of a thermoplastic resin film laminated on the other surface of the polarizing film via an adhesive layer;
A polarizing plate comprising: The polarizing plate according to claim 1, wherein the epoxy compound does not contain an aromatic ring in the molecule.   The polarizing plate according to claim 2, wherein the epoxy compound has at least one epoxy group bonded to an alicyclic ring. The polarizing plate according to claim 1, wherein the active energy ray-curable compound further contains an oxetane compound. The polarizing plate according to any one of claims 1 to 4, wherein the active energy ray-curable compound further comprises a (meth) acrylic compound having at least one (meth) acryloyloxy group in the molecule.   The polarizing plate according to claim 1, wherein the first protective layer has a thickness of 0.1 to 10 μm.   The polarizing plate according to claim 1, wherein the second protective layer is made of a cellulose acetate-based resin film.   The polarizing plate according to claim 1, wherein the adhesive layer is made of a cured product of a curable resin composition containing an active energy ray-curable compound.   The polarizing plate according to claim 1, further comprising a pressure-sensitive adhesive layer laminated on a surface of the first protective layer opposite to the polarizing film side.   The polarizing plate according to claim 1, which is used in a liquid crystal display device that operates in a transverse electric field mode. A liquid crystal cell, and a pair of polarizing plates disposed on both sides of the liquid crystal cell,
At least one of the pair of polarizing plates is the polarizing plate according to claim 9, wherein the liquid crystal display device is bonded to the liquid crystal cell on the pressure-sensitive adhesive layer side. A liquid crystal cell, and a pair of polarizing plates disposed on both sides of the liquid crystal cell,
Both said pair of polarizing plates are polarizing plates of Claim 9, The liquid crystal display device currently bonded by the said liquid crystal cell by the adhesive layer side.   The liquid crystal cell is a liquid crystal cell that operates in a transverse electric field mode that includes two substrates and a liquid crystal layer that is sandwiched between the substrates and is aligned substantially parallel to the substrate when no voltage is applied. The liquid crystal display device according to claim 11. A polarizing film having a dichroic dye adsorbed and oriented on a polyvinyl alcohol resin;
1st which consists of hardened | cured material of the curable resin composition containing the active energy ray-curable compound containing the epoxy-type compound which has at least 1 epoxy group in the molecule | numerator laminated | stacked on the one surface of the said polarizing film. A protective layer;
A second protective layer made of a thermoplastic resin film, laminated on the other surface of the polarizing film via an adhesive layer, and a method for producing a polarizing plate comprising:
A coating layer forming step of providing a coating layer of the curable resin composition on the surface of the substrate;
A coating layer laminating step for laminating a coating layer of a curable resin composition provided on the surface of the base material on one surface of the polarizing film;
A film bonding step of bonding the second protective layer to the other surface of the polarizing film via an adhesive;
A curing step of curing the coating layer and the adhesive;
A substrate removing step for removing the substrate;
The manufacturing method of a polarizing plate provided with.   The method for producing a polarizing plate according to claim 14, wherein in the curing step, the coating layer and the adhesive are cured simultaneously by irradiating active energy rays from the substrate side.

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