JP5348581B2 - Retardation film with pressure-sensitive adhesive layer, and elliptically polarizing plate and liquid crystal display device using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a retardation film with adhesive layer which is improved in adhesion between the retardation film made of a polypropylene resin and the adhesive layer, and to provide an elliptical polarizing plate and a liquid crystal display device using the retardation film. <P>SOLUTION: The retardation film 10 with adhesive layer is composed of a retardation film 20 made of the polypropylene resin, a primer layer 30 and an adhesive layer 40, stacked in this order. The primer layer 30 contains a water-soluble epoxy resin and a polyvinylalcohol resin having a saponification degree of &ge;95.0 mol%. The elliptical polarizing plate and the liquid crystal display device use the retardation film. <P>COPYRIGHT: (C)2009,JPO&amp;INPIT

Description

  The present invention relates to a retardation film, and more particularly to a retardation film with an adhesive layer obtained by laminating a specific primer layer and an adhesive layer on a retardation film made of a polypropylene resin. The present invention also relates to an elliptically polarizing plate and a liquid crystal display device using the retardation film with an adhesive layer.

  In recent years, liquid crystal display devices have rapidly spread as information display devices such as mobile phones, portable information terminals, computer monitors, and televisions by taking advantage of low power consumption, low voltage operation, light weight, and thinness. Yes. With the development of liquid crystal technology, liquid crystal displays in various modes have been proposed, and problems with liquid crystal displays such as response speed, contrast, and narrow viewing angle are being solved. However, it is still pointed out that the viewing angle is narrower than that of a cathode ray tube (CRT), and various attempts have been made to expand the viewing angle.

  One means for widening the viewing angle in a liquid crystal display is to use a retardation film that matches the mode of the liquid crystal. Examples thereof include a birefringent film made of a stretched film of various plastics, a film in which a discotic liquid crystal or a nematic liquid crystal is oriented and fixed, and a film substrate on which the above liquid crystal layer is formed.

  Specific examples of the birefringent film include stretched films such as polycarbonate resin, polystyrene resin, polymethyl methacrylate resin, polyolefin resin, and polyamide resin.

  As a retardation film of polyolefin resin, an amorphous cyclic polyolefin resin, also called alicyclic polyolefin or norbornene resin, is relatively excellent in heat resistance and moisture resistance, excellent in transparency, and retardation. It is widely used for the reason that the value can be adjusted relatively easily. For example, Patent Document 1 shows an example in which a λ / 2 stretched film or a λ / 4 stretched film is produced from a cyclic polyolefin film (see Examples). Patent Document 2 discloses that a polypropylene resin is applied to a retardation film. However, non-polar polyolefin resins are often inferior in adhesive strength with pressure-sensitive adhesives, and thus have been required to be improved.

On the other hand, Patent Document 3 discloses that a composition containing a water-soluble epoxy resin is used as a primer layer interposed between two types of retardation plates.
Japanese Patent Laid-Open No. 11-149015 JP 2007-286615 A JP 2007-272176 A

  A retardation film made of a polypropylene-based resin, which is a chain polyolefin, is generally inferior in adhesiveness to the pressure-sensitive adhesive layer compared to a cyclic polyolefin-based resin, and is therefore bonded to the glass substrate of the liquid crystal cell using the pressure-sensitive adhesive layer. When an optical member made of a laminate of a polarizing plate and a retardation film is peeled from the liquid crystal cell, a problem may occur in which the adhesive layer is peeled off from the optical member and remains on the liquid crystal cell side. there were.

  The present invention has been made to solve such problems, and an object thereof is to provide a retardation film with a pressure-sensitive adhesive layer in which the adhesion between the phase difference film made of polypropylene resin and the pressure-sensitive adhesive layer is improved. That is. Another object of the present invention is to provide an elliptically polarizing plate using the retardation film with a pressure-sensitive adhesive layer, and further a liquid crystal display device using the elliptically polarizing plate.

The present invention includes a retardation film made of a polypropylene resin, the phase difference with one primer layer that is laminated on the surface of the film, the pressure-sensitive adhesive to be laminated on the surface opposite to the retardation film side of the primer layer a layer, made of, the primer layer, provides a water-soluble epoxy resin, polyvinyl alcohol resin and the retardation film pressure-sensitive adhesive layer containing at saponification degree 95.0 mol% or more.

  Here, the retardation film is made of a copolymer of propylene and ethylene, and the content of the structural unit derived from ethylene is preferably 10% by weight or less. The retardation film may be a quarter wavelength plate.

  Moreover, this invention provides the elliptically polarizing plate by which a polarizing plate is laminated | stacked on the phase difference film in the phase difference film with an adhesive layer in any one of the said. The elliptically polarizing plate of the present invention may further include a half-wave plate between the retardation film and the polarizing plate.

The present invention further includes a liquid crystal cell and the elliptically polarizing plate of the present invention laminated on one or both sides of the liquid crystal cell, and the elliptically polarizing plate has a pressure-sensitive adhesive layer-attached retardation film side facing the liquid crystal cell. as described above, the liquid crystal display device that is stuck to the liquid crystal cell is provided with an adhesive layer.

  ADVANTAGE OF THE INVENTION According to this invention, the phase difference film with an adhesive layer in which the adhesiveness of a phase difference film and an adhesive layer was improved, and an elliptically polarizing plate using the same are provided. According to the retardation film with an adhesive layer and the elliptical polarizing plate, when the retardation film or the polarizing plate having the retardation film bonded to the glass substrate of the liquid crystal cell is peeled off from the liquid crystal cell and reattached, It can be prevented from remaining on the glass substrate. Such a retardation film of the present invention and an elliptically polarizing plate using the same can be suitably applied to a liquid crystal display device and the like.

  Hereinafter, the present invention will be described in detail with reference to embodiments. FIG. 1 is a schematic cross-sectional view showing a preferred example of the retardation film with an adhesive layer of the present invention. As shown in FIG. 1, a retardation film 10 with an adhesive layer according to the present invention includes a retardation film 20 made of a polypropylene resin, a primer layer 30 laminated on one surface of the retardation film 20, and a primer And an adhesive layer 40 laminated on the layer 30. Hereinafter, each layer will be described in detail.

<< retardation film with adhesive layer >>
<Phase difference film>
In the present invention, a polypropylene resin is stretched to obtain a retardation film. Since the polypropylene resin film is crystalline, the expression rate of the retardation value is extremely high, and a large retardation value can be easily obtained by stretching. Therefore, by using a polypropylene resin, a retardation film having a desired retardation value can be obtained with a thin film thickness.

Polypropylene resin has a difference (birefringence) Δn ₄₀₀ between the in-plane maximum refractive index and the minimum refractive index at a wavelength of ₄₀₀ nm (birefringence) and a difference (birefringence) between the in-plane maximum refractive index and the minimum refractive index at a wavelength of 500 nm. ) for the ratio between _{Δn 500 (Δn 400 / Δn 500} ) is less than 1.05, when a combination of a half-wave plate and a quarter-wave plate formed of each polypropylene resin, excellent wideband It can be a quarter wave plate. In this specification, the value of Δn ₄₀₀ / Δn ₅₀₀ described above is defined as “wavelength dispersion of phase difference” (in this specification, sometimes simply referred to as “wavelength dispersion”).

Furthermore, since the polypropylene-based resin has a small photoelastic coefficient of about 2 × 10 ⁻¹³ cm ² / dyne, the retardation film is made of polypropylene-based resin, so that a half-wave plate and a quarter-wavelength are obtained. Bonding unevenness can be suppressed at the time of bonding with a plate or at the time of bonding with a linear polarizing plate. Moreover, white spots in the heat resistance test can be suppressed. In addition, since the polypropylene-based resin can be stretched at a high magnification, it is possible to produce a completely uniaxial film by transverse stretching, and it is possible to achieve thinning and widening at the same time, and excellent use efficiency.

  In the present invention, a raw film is obtained by depositing the polypropylene resin, and then stretched to develop a retardation to obtain a retardation film. The film thickness of the retardation film can be, for example, about 25 μm or less, and preferably 20 μm or less. When the film thickness exceeds 25 μm, the merit of thinning becomes difficult to be exhibited effectively. Moreover, when the film thickness is too small, wrinkles and the like are likely to occur in the film, and the handling property at the time of winding and bonding tends to be deteriorated. Therefore, the thickness of the retardation film is preferably 5 μm or more, and more preferably 8 μm or more.

The retardation film used in the present invention preferably has an in-plane retardation value R ₀ in the range of 70 to 160 nm. Further, N _z coefficient of the retardation film is preferably in the range of 0.9 to 1.6, especially more preferably in the range of 0.95 to 1.05. From the above range, the in-plane retardation value R ₀ and the N _z coefficient of the retardation film can be appropriately selected according to the characteristics required for the applied liquid crystal display device. The refractive index of the refractive index n _y, in the thickness direction of the in-plane slow axis direction of the refractive index of the retardation film n _x, plane fast axis direction (direction orthogonal with the slow axis and the plane) _Where n _{z is} the thickness of the retardation film and d is the thickness of the retardation film, the in-plane retardation value R ₀ , the retardation value R _{th in the} thickness direction, and the N _z coefficient are represented by the following formulas (I ), (II) and (III).

_{R 0 = (n x -n y} ) × d (I)
_Rth = [( _nx + _ny ) / 2- _nz ] * d (II)
_{N z = (n x -n z} ) / (n x -n y) (III)
Further, from the above formulas (I), (II) and (III), the relationship between the N _z coefficient, the in-plane retardation value R ₀ and the thickness direction retardation value R _th is expressed by the following expression (IV): Can be represented.

N _z = R _th / R ₀ +0.5 (IV)
In addition, when the _Nz coefficient is approximately 1, it means that _ny and _nz are approximately equal from the above formula (III), and thus such a retardation film is almost completely uniaxial.

(Polypropylene resin)
Next, the polypropylene resin constituting the retardation film used in the present invention will be described in more detail. The polypropylene resin constituting the retardation film used in the present invention can be produced by a method of homopolymerizing propylene or a method of copolymerizing propylene and another copolymerizable comonomer using a polymerization catalyst. . As the polymerization catalyst, a conventionally known polymerization catalyst can be used, and examples thereof include the following.
(1) Ti—Mg-based catalyst comprising a solid catalyst component containing magnesium, titanium and halogen as essential components,
(2) a catalyst system in which a solid catalyst component containing magnesium, titanium and halogen as essential components is combined with an organoaluminum compound and, if necessary, a third component such as an electron donating compound,
(3) Metallocene catalysts.

  Among the catalyst systems described above, in the production of the polypropylene resin used in the retardation film of the present invention, an organic aluminum compound and an electron donating compound are combined with a solid catalyst component containing magnesium, titanium and halogen as essential components. Catalytic systems are most commonly used. Examples of the solid catalyst component containing magnesium, titanium, and halogen as essential components include catalyst systems described in JP-A-61-218606, JP-A-61-287904, JP-A-7-216017, and the like. Can be mentioned. As the organoaluminum compound, triethylaluminum, triisobutylaluminum, a mixture of triethylaluminum and diethylaluminum chloride, tetraethyldialumoxane and the like can be preferably used. As the electron donating compound, cyclohexylethyldimethoxysilane, tert-butylpropyldimethoxysilane, tert-butylethyldimethoxysilane, dicyclopentyldimethoxysilane and the like can be preferably used.

  Examples of the metallocene catalyst include catalyst systems described in Japanese Patent No. 2587251, Japanese Patent No. 2627669, Japanese Patent No. 2668732, and the like.

  Polypropylene resin is, for example, a solution polymerization method using an inert solvent typified by a hydrocarbon compound such as hexane, heptane, octane, decane, cyclohexane, methylcyclohexane, benzene, toluene, xylene, or a liquid monomer as a solvent. It can be produced by a bulk polymerization method or a gas phase polymerization method in which a gaseous monomer is polymerized as it is. Polymerization by these methods may be carried out batchwise or continuously.

  The stereoregularity of the polypropylene resin may be any of isotactic, syndiotactic, and atactic. In the present invention, a syndiotactic or isotactic polypropylene resin is preferably used from the viewpoint of heat resistance.

  The polypropylene resin that constitutes the retardation film used in the present invention can be composed of a propylene homopolymer, and is composed of propylene as a main component and a comonomer copolymerizable therewith in a small proportion. There may be. By using a copolymer, the processability and transparency of the polypropylene resin can be improved. When the copolymer is used, the content of the comonomer-derived constituent unit in the copolymer is, for example, 20% by weight or less, preferably 10% by weight or less, more preferably 7% by weight or less. Moreover, the content rate of the structural unit derived from the comonomer in a copolymer becomes like this. Preferably it is 1 weight% or more, More preferably, it is 3 weight% or more. When the content of the comonomer-derived structural unit exceeds 10% by weight, the melting point of the resin is lowered, and the heat resistance tends to deteriorate. Further, when the content of the comonomer-derived structural unit is less than 1% by weight, effects such as improvement in processability and transparency that can be obtained by copolymerization tend not to be recognized. In addition, when setting it as the copolymer of two or more types of comonomers and polypropylene, it is preferable that the total content rate of the structural unit derived from all the comonomers contained in the copolymer is the said range. The content of the comonomer-derived constituent unit in the copolymer is measured by infrared (IR) spectrum according to the method described on page 616 of “Polymer Analysis Handbook” (1995, published by Kinokuniya Shoten). Can be obtained.

  Examples of the comonomer copolymerizable with propylene include ethylene and an α-olefin having 4 to 20 carbon atoms. Specific examples of the α-olefin having 4 to 20 carbon atoms include the following.

  1-butene, 2-methyl-1-propene (above, 4 carbon atoms); 1-pentene, 2-methyl-1-butene, 3-methyl-1-butene (above, 5 carbon atoms); Hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3-dimethyl- 1-butene (above, 6 carbon atoms); 1-heptene, 2-methyl-1-hexene, 2,3-dimethyl-1-pentene, 2-ethyl-1-pentene, 2-methyl-3-ethyl- 1-butene (above, 7 carbon atoms); 1-octene, 5-methyl-1-heptene, 2-ethyl-1-hexene, 3,3-dimethyl-1-hexene, 2-methyl-3-ethyl- 1-pentene, 2,3,4-trimethyl-1-pen 2-propyl-1-pentene, 2,3-diethyl-1-butene (above, 8 carbon atoms); 1-nonene (9 carbon atoms); 1-decene (10 carbon atoms); Undecene (11 carbon atoms); 1-dodecene (12 carbon atoms); 1-tridecene (13 carbon atoms); 1-tetradecene (14 carbon atoms); 1-pentadecene (15 carbon atoms); Hexadecene (16 carbon atoms); 1-heptadecene (17 carbon atoms); 1-octadecene (18 carbon atoms); 1-nonadecene (19 carbon atoms) and the like.

  Among the copolymerizable comonomers, ethylene and an α-olefin having 4 to 12 carbon atoms are preferably used from the viewpoint of processability. Examples of the α-olefin having 4 to 12 carbon atoms preferably used include 1-butene, 2-methyl-1-propene; 1-pentene, 2-methyl-1-butene, and 3-methyl-1-butene; 1-hexene, 2-ethyl-1-butene, 2,3-dimethyl-1-butene, 2-methyl-1-pentene, 3-methyl-1-pentene, 4-methyl-1-pentene, 3,3- 1-heptene, 2-methyl-1-hexene, 2,3-dimethyl-1-pentene, 2-ethyl-1-pentene, 2-methyl-3-ethyl-1-butene; Octene, 5-methyl-1-heptene, 2-ethyl-1-hexene, 3,3-dimethyl-1-hexene, 2-methyl-3-ethyl-1-pentene, 2,3,4-trimethyl-1- Penten, 2-propi 1-pentene, 2,3-diethyl-1-butene; 1-nonene, 1-decene, 1-undecene; 1-dodecene, and the like. From the viewpoint of copolymerizability with propylene, ethylene, 1-butene, 1-pentene, 1-hexene and 1-octene are preferable, and ethylene, 1-butene and 1-hexene are more preferable. Accordingly, preferred copolymers include propylene / ethylene copolymers, propylene / 1-butene copolymers and propylene / 1-hexene copolymers.

  The copolymer of propylene and a comonomer copolymerizable therewith may be a random copolymer or a block copolymer, but improves the transparency and workability as a retardation film. From this point of view, a random copolymer mainly composed of propylene is preferable. Of these, a random copolymer of propylene and ethylene is preferable.

  The polypropylene resin constituting the retardation film used in the present invention has a melt flow rate (MFR) measured at a temperature of 230 ° C. and a load of 21.18 N in accordance with JIS K 7210 of 0.1 to 200 g / 10 min. In particular, it is preferably in the range of 0.5 to 50 g / 10 minutes. By using a polypropylene resin having an MFR in this range, a uniform film can be obtained without imposing a large load on the extruder.

  The polypropylene resin may contain a known additive as long as the effects of the present invention are not impaired. Examples of the additive include an antioxidant, an ultraviolet absorber, an antistatic agent, a lubricant, a nucleating agent, an antifogging agent, and an antiblocking agent. Examples of antioxidants include phenolic antioxidants, phosphorus antioxidants, sulfur antioxidants, hindered amine light stabilizers, and the like, and for example, phenolic antioxidant mechanisms in one molecule. It is also possible to use a composite antioxidant having a unit having both a phosphorus-based antioxidant mechanism and a phosphorus-based antioxidant mechanism. Examples of the UV absorber include UV absorbers such as 2-hydroxybenzophenone and hydroxyphenylbenzotriazole, and benzoate UV blockers. The antistatic agent may be polymer type, oligomer type or monomer type. Examples of the lubricant include higher fatty acid amides such as erucic acid amide and oleic acid amide, higher fatty acids such as stearic acid, and salts thereof. Examples of the nucleating agent include sorbitol nucleating agents, organophosphate nucleating agents, and polymer nucleating agents such as polyvinylcycloalkane. As the anti-blocking agent, fine particles having a spherical shape or a shape close thereto can be used regardless of inorganic type or organic type. A plurality of these additives may be used in combination.

(Raw film of polypropylene resin)
In the present invention, when producing a retardation film made of a polypropylene resin, first, the original film is obtained by forming the polypropylene resin. The raw film is preferably transparent and substantially free of in-plane retardation. The method for producing a polypropylene resin film is not particularly limited. For example, an extrusion molding method from a molten resin; a resin dissolved in an organic solvent is cast on a flat plate, and the solvent is removed to produce the original film. An original film of polypropylene resin having substantially no in-plane retardation can be obtained by a solvent casting method for forming a film.

  As an example of a method for producing a raw film, a film forming method (extrusion molding method) by extrusion will be described in detail. In the extrusion molding method, a polypropylene resin is melt-kneaded by rotation of a screw in an extruder and extruded from a T die into a sheet. The temperature of the molten sheet to be extruded is about 180 to 300 ° C. If the temperature of the molten sheet at this time is lower than 180 ° C., the spreadability is not sufficient, the thickness of the resulting film becomes non-uniform, and there is a possibility that the film has phase difference unevenness. Further, when the temperature exceeds 300 ° C., the resin is easily deteriorated or decomposed, and bubbles may be generated in the sheet or carbides may be contained.

The extruder may be a single screw extruder or a twin screw extruder. For example, when a single screw extruder is used, L / D, which is the ratio of the screw length L to the diameter D, is about 24 to 36, the screw groove space volume V ₁ in the resin supply section, and the screw groove in the resin metering section. The compression ratio, which is the ratio (V ₁ / V ₂ ) to the space volume V ₂ , is about 1.5 to 4 and is a full flight type, a barrier type, or a screw having a Maddock type kneading part. Can be used. From the viewpoint of suppressing deterioration and decomposition of the polypropylene-based resin and uniformly melting and kneading, the barrier type L / D is 28 to 36 and the compression ratio V ₁ / V ₂ is 2.5 to 3.5. It is preferable to use a screw. Moreover, in order to suppress deterioration and decomposition | disassembly of polypropylene resin as much as possible, it is preferable to make the inside of an extruder into a nitrogen atmosphere or a vacuum. Furthermore, in order to remove the volatile gas generated when the polypropylene-based resin deteriorates or decomposes, it is also preferable to provide an orifice of about 1 mmφ to 5 mmφ at the tip of the extruder to increase the resin pressure at the tip of the extruder. Increasing the resin pressure at the leading end of the extruder by installing an orifice means increasing the back pressure at the leading end, thereby improving the stability of extrusion. The diameter of the orifice to be used is more preferably 2 mmφ or more and 4 mmφ or less.

  The T-die used for extrusion preferably has no fine steps or scratches on the resin flow path surface, and the lip portion is plated or coated with a material having a low coefficient of friction with the molten polypropylene resin. Further, it is preferable to have a sharp edge shape in which the lip tip is polished to 0.3 mmφ or less. Examples of the material having a small friction coefficient include tungsten carbide type and fluorine type special plating. By using such a T-die, it is possible to suppress the generation of the eyes, and at the same time, it is possible to suppress the die line, so that a raw film having excellent appearance uniformity can be obtained. In the T-die, the manifold has a coat hanger shape and preferably satisfies the following condition (1) or (2), and more preferably satisfies the condition (3) or (4).

(1) When the lip width of the T die is less than 1500 mm: the thickness direction length of the T die> 180 mm,
(2) When the lip width of the T die is 1500 mm or more: the thickness direction length of the T die> 220 mm,
(3) When the lip width of the T die is less than 1500 mm: the length in the height direction of the T die> 250 mm,
(4) When the lip width of the T die is 1500 mm or more: Length in the height direction of the T die> 280 mm.

  By using a T die that satisfies these conditions, the flow of the molten polypropylene resin inside the T die can be adjusted, and the lip portion can be extruded while suppressing thickness unevenness, so that the thickness is increased. An original film having excellent accuracy and a more uniform retardation can be obtained.

  From the viewpoint of suppressing the extrusion fluctuation of the polypropylene resin, it is preferable to attach a gear pump via an adapter between the extruder and the T die. In addition, it is preferable to attach a leaf disk filter to remove foreign substances in the polypropylene resin.

  The molten sheet extruded from the T-die is between a metal cooling roll (also referred to as a chill roll or a casting roll) and a touch roll including an elastic body that rotates by pressing in the circumferential direction of the metal cooling roll. A desired original fabric film can be obtained by clamping and solidifying by cooling. In this case, the touch roll may be one in which an elastic body such as rubber is directly on the surface, or may be one in which the surface of the elastic body roll is covered with an outer cylinder made of a metal sleeve. When using a touch roll in which the surface of the elastic roll is covered with an outer cylinder made of a metal sleeve, cooling is usually performed by directly sandwiching a molten sheet of polypropylene resin between the metal cooling roll and the touch roll. . On the other hand, in the case of using a touch roll whose surface is an elastic body, a biaxially stretched film of a thermoplastic resin can be interposed between the molten sheet of polypropylene resin and the touch roll for sandwiching.

  When the molten sheet of polypropylene resin is cooled and solidified by being sandwiched between the cooling roll and the touch roll as described above, the surface temperature of the cooling roll and the touch roll may be lowered to rapidly cool the molten sheet. preferable. For example, the surface temperature of both rolls is preferably adjusted to a range of 0 ° C. or higher and 30 ° C. or lower. When these surface temperatures exceed 30 ° C., it takes time to cool and solidify the molten sheet, so that the crystal component in the polypropylene resin grows, and the resulting film may be inferior in transparency. . The surface temperature of the roll is preferably less than 30 ° C, more preferably less than 25 ° C. On the other hand, when the surface temperature of the roll is lower than 0 ° C., the surface of the metal cooling roll is dewed and water droplets are attached, which tends to deteriorate the appearance of the raw film.

  Since the surface state of the metal cooling roll used is transferred to the surface of the polypropylene resin film, there is a possibility that the thickness accuracy of the resulting polypropylene resin film may be lowered if the surface is uneven. . Therefore, it is preferable that the surface of the metal cooling roll is in a mirror surface state as much as possible. Specifically, the roughness of the surface of the metal cooling roll is preferably 0.3 S or less, more preferably 0.1 S to 0.2 S, expressed as a standard sequence of the maximum height. .

  As for the metal roll and the touch roll forming the nip part, the surface hardness of the elastic body is 65 to 80 as a value measured by a spring type hardness test (A type) defined in JIS K 6301. It is preferable that there is, more preferably 70-80. By using a rubber roll having such a surface hardness, it becomes easy to maintain a uniform linear pressure applied to the molten sheet, and a bank of the molten sheet (resin pool) is provided between the metal cooling roll and the touch roll. ) Can be easily formed into a film.

  The pressure (linear pressure) when sandwiching the molten sheet is determined by the pressure for pressing the touch roll against the metal cooling roll. The linear pressure is preferably 50 N / cm or more and 300 N / cm or less, and more preferably 100 N / cm or more and 250 N / cm or less. By setting the linear pressure within the above range, it becomes easy to produce an original film of polypropylene resin while maintaining a constant linear pressure without forming a bank.

  When sandwiching a biaxially stretched film of a thermoplastic resin together with a molten sheet of polypropylene resin between a metal cooling roll and a touch roll, the thermoplastic resin constituting the biaxially stretched film is a polypropylene resin and Any resin that does not strongly heat-seal can be used. Specific examples include polyester, polyamide, polyvinyl chloride, polyvinyl alcohol, ethylene-vinyl alcohol copolymer, and polyacrylonitrile. Among these, polyesters that have little dimensional change due to humidity, heat, and the like are most preferable. In this case, the thickness of the biaxially stretched film is usually about 5 to 50 μm, preferably 10 to 30 μm.

  In this method, the distance (air gap) from the lip of the T die to the pressure between the metal cooling roll and the touch roll is preferably 200 mm or less, and more preferably 160 mm or less. The molten sheet extruded from the T-die is stretched from the lip to the roll, and orientation tends to occur. By shortening the air gap as described above, a film having a smaller orientation can be obtained. The lower limit value of the air gap is determined by the diameter of the metal cooling roll to be used, the diameter of the touch roll, and the tip shape of the lip to be used, and is usually 50 mm or more.

  The processing speed for producing a polypropylene resin raw film by this method is determined by the time required for cooling and solidifying the molten sheet. When the diameter of the metal cooling roll to be used is increased, the distance at which the molten sheet is in contact with the cooling roll becomes longer, so that production at a higher speed is possible. Specifically, when a 600 mmφ metal cooling roll is used, the processing speed is about 5 to 20 m / min at the maximum.

  The molten sheet sandwiched between the metal cooling roll and the touch roll is cooled and solidified by contact with the roll. And after slitting an edge part as needed, it is wound up by a winder and turns into a raw film. Under the present circumstances, in order to protect the surface until it uses a raw film, you may wind in the state which bonded the surface protection film which consists of another thermoplastic resin to the single side | surface or both surfaces. When a molten sheet of polypropylene resin is sandwiched between a metal cooling roll and a touch roll together with a biaxially stretched film made of a thermoplastic resin, the biaxially stretched film is used as one surface protective film. You can also.

(Method for producing retardation film)
The retardation film used in the present invention can be produced by laterally stretching a raw film made of polypropylene resin as described above. Here, transverse stretching refers to stretching a long film unwound from a roll in the width direction (lateral direction).

The transverse stretching usually has the following steps.
(A) A preheating step of preheating the raw film at a temperature near the melting point of the polypropylene resin;
(B) a stretching step of stretching the preheated film in the transverse direction at a temperature lower than the preheating temperature; and
(C) The heat setting process which heat-sets the film extended | stretched to the horizontal direction.

  As a typical transverse stretching method, there is a tenter method. The tenter method is a method in which an original film, which is fixed at both ends in the film width direction with a chuck, is stretched in an oven with an increased chuck interval. A stretching machine (tenter stretching machine) used for the tenter method is usually provided with a mechanism capable of independently adjusting the temperatures in the zone for performing the preheating step, the zone for performing the stretching step, and the zone for performing the heat setting step. By performing transverse stretching using such a tenter stretching machine, a retardation film having excellent axial accuracy and a uniform retardation can be obtained.

  The pre-heating step (A) of transverse stretching is a step that is installed before the step of stretching the film in the width direction, and is a step of heating the film to a temperature sufficient to stretch the film. The preheating temperature in the preheating step means an atmospheric temperature in a zone where the oven preheating step is performed, and a temperature near the melting point of the polypropylene resin film to be stretched is adopted. The residence time in the preheating step of the stretched film is preferably 30 to 120 seconds. When the residence time in this preheating process is less than 30 seconds, stress is dispersed when the film is stretched in the stretching process, which adversely affects the axial accuracy and retardation uniformity as the retardation film. There is a possibility, and when the residence time exceeds 120 seconds, the film receives heat more than necessary, and the film may partially melt and draw down (drip down). The residence time in the preheating step is more preferably 30 to 60 seconds.

The stretching step (B) of transverse stretching is a step of stretching the film in the width direction. The stretching temperature in this stretching step is usually lower than the preheating temperature. The stretching temperature in the stretching process means the atmospheric temperature in the zone where the oven stretching process is performed. By stretching the preheated film at a temperature lower than that in the preheating step, the film can be stretched uniformly, and as a result, a retardation film excellent in optical axis and retardation uniformity can be obtained. The stretching temperature is preferably 5 to 20 ° C lower than the preheating temperature in the preheating step, and more preferably 7 to 15 ° C. The draw ratio at this time may be appropriately selected from the range of about 3 to 10 times in the direction in which the optical axis is expressed (the direction of the slow axis), preferably 3 according to the required retardation value. It is a range of ~ 6 times. With the draw ratio at this time more than three times, the N _z coefficient of the can be in the range of 0.9 to 1.1. On the other hand, if the draw ratio becomes too large, the uniformity of the retardation value may be impaired, so it is preferable to limit it to about 10 times.

  The transverse stretching heat setting step (C) is a step of allowing the film to pass through a predetermined temperature zone in the oven while maintaining the film width at the end of the stretching step. In order to effectively improve the stability of optical properties such as phase difference and optical axis of the film, the heat setting temperature is from 5 ° C. lower than the stretching temperature in the stretching step to 30 ° C. higher than the stretching temperature. It is preferable to be within the range.

  The transverse stretching process may further include a thermal relaxation process. In the tenter method, this thermal relaxation process is usually performed between the stretching process and the heat setting process, and the thermal relaxation zone is usually provided so that the temperature can be set independently of the other zones. It is. Specifically, in the thermal relaxation process, after the film is stretched to a predetermined width in the stretching process, the chuck interval is narrowed by a few percent in order to remove unnecessary strain, and is usually smaller than the interval at the end of stretching. Narrowing by about 0.5 to 7% is performed.

<Primer layer>
The primer layer (primer layer 30 in FIG. 1) constituting the retardation film with an adhesive layer of the present invention contains a water-soluble epoxy resin and a polyvinyl alcohol resin. By interposing such a primer layer, the adhesion between the retardation film and the pressure-sensitive adhesive layer can be improved. Here, “containing a water-soluble epoxy resin and a polyvinyl alcohol-based resin” includes a crosslinked cured product of a water-soluble epoxy resin and a polyvinyl alcohol-based resin, or together with the crosslinked cured product, unreacted. It means to contain a water-soluble epoxy resin and / or a polyvinyl alcohol resin.

  The primer layer can be formed by coating a resin composition containing a water-soluble epoxy resin and a polyvinyl alcohol-based resin on a retardation film and then performing a drying treatment. As the resin composition, a resin composition containing water-soluble epoxy resin and polyvinyl alcohol resin and water as a main solvent (hereinafter also referred to as primer coating solution) is preferably used. By using water as the main solvent, it is possible to maintain the retardation value of the retardation film and the accuracy of the slow axis even after application of the primer coating liquid. In addition, a water-soluble organic solvent such as alcohols may be appropriately added for adjusting the viscosity of the primer coating solution or adjusting the surface tension, or in anticipation of the defoaming effect. Examples of alcohols include methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, ethylene glycol and the like.

  Examples of the water-soluble epoxy resin contained in the primer coating liquid include, for example, a polyalkylene polyamine such as diethylenetriamine and triethylenetetramine and a polyamide polyamine obtained by a reaction of a dicarboxylic acid such as adipic acid with epichlorohydrin. The polyamide epoxy resin obtained by making it react can be mentioned. Commercially available products of such polyamide epoxy resins include “Smilease Resin 650 (30)” and “Smilease Resin 675” (both trade names) sold by Sumika Chemtex Co., Ltd.

  The addition amount of the water-soluble epoxy resin is preferably about 0.2 to 5.5 parts by weight with respect to 100 parts by weight of the solvent (in the case where only water is used as the solvent, water part by weight). When the addition amount of the water-soluble epoxy resin is less than 0.2 parts by weight with respect to 100 parts by weight of the solvent, sufficient adhesion between the retardation film and the pressure-sensitive adhesive layer tends not to be obtained. is there. Moreover, when the addition amount of the water-soluble epoxy resin exceeds 5.5 parts by weight with respect to 100 parts by weight of the solvent, the reaction with the added polyvinyl alcohol resin cannot be ignored, and the primer coating liquid The viscosity tends to increase and gelled products tend to be generated, which is not preferable. By setting the amount of the water-soluble epoxy resin within the above range, a primer layer that provides sufficient adhesion between the retardation film and the pressure-sensitive adhesive layer can be formed, but the concentration of the water-soluble epoxy resin is relatively high. By selecting the addition amount of the water-soluble epoxy resin from the range of about 0.5 to 5.5 parts by weight, the adhesion can be further improved. However, the addition amount of the water-soluble epoxy resin may be selected from a range in which the water-soluble epoxy resin concentration is relatively low, for example, about 0.2 to 1.5 parts by weight.

  Examples of the polyvinyl alcohol resin contained in the primer coating solution include partially saponified polyvinyl alcohol and fully saponified polyvinyl alcohol, as well as carboxyl group-modified polyvinyl alcohol, acetoacetyl group-modified polyvinyl alcohol, and methylol group-modified polyvinyl alcohol. Further, it may be a modified polyvinyl alcohol-based resin such as amino group-modified polyvinyl alcohol. As a commercially available product of a suitable polyvinyl alcohol-based resin, “PVA-403” which is a partially saponified polyvinyl alcohol sold by Kuraray Co., Ltd., and “KL-506” which is a carboxyl group-modified partially saponified polyvinyl alcohol, respectively. , “KL-318”, “Gosefimer Z200” (both trade names), which are modified polyvinyl alcohols having an acetoacetyl group sold by Nippon Gosei Co., Ltd., and the like.

  In the present invention, the saponification degree of the polyvinyl alcohol resin is 95 mol% or more. When the degree of saponification is less than 95 mol%, the adhesiveness with a retardation film made of a polypropylene resin tends to decrease, and as a result, a retardation film with an adhesive layer or a polarizing plate using the same is obtained. When peeling from the liquid crystal cell, the pressure-sensitive adhesive layer may remain on the liquid crystal cell side.

  The addition amount of the polyvinyl alcohol-based resin is preferably about 1 to 25 parts by weight with respect to 100 parts by weight of the solvent (100% by weight of water when only water is used as the solvent). When the addition amount of the polyvinyl alcohol-based resin is less than 1 part by weight with respect to 100 parts by weight of the solvent, sufficient adhesion between the retardation film and the pressure-sensitive adhesive layer tends not to be obtained. Further, when the addition amount of the polyvinyl alcohol-based resin exceeds 25 parts by weight with respect to 100 parts by weight of the solvent, the viscosity of the aqueous solution is remarkably increased, and the solution stability tends to be decreased. Absent. By setting the addition amount of the polyvinyl alcohol resin within the above range, a primer layer that gives sufficient adhesion between the retardation film and the pressure-sensitive adhesive layer can be formed, but the concentration of the polyvinyl alcohol resin is relatively high. For example, by selecting the addition amount of the polyvinyl alcohol resin from the range of about 5 to 25 parts by weight, the adhesion can be further improved. However, the addition amount of the polyvinyl alcohol resin may be selected from a range where the polyvinyl alcohol resin concentration is relatively low, for example, about 1 to 6 parts by weight.

  The water-soluble epoxy resin functions as a curing agent for the polyvinyl alcohol resin. As the water-soluble epoxy resin has higher reactivity with the polyvinyl alcohol-based resin, the cross-linking density after the reaction becomes higher, so that the resulting primer layer exhibits good water resistance. However, if the reactivity of the water-soluble epoxy resin is too high, the reaction tends to occur in the primer coating solution. That is, the water resistance does not increase because the water-soluble epoxy resin reacts with the solvent and deactivates, or it reacts with the polyvinyl alcohol resin in the primer coating solution and the viscosity in the primer coating solution However, it is easy to cause a problem such that a good coating film cannot be obtained. In order to form a primer layer with good water resistance, it is important to increase the reactivity at the time of solvent removal as much as possible while ensuring the stability of the water-soluble epoxy resin in the primer coating solution. . In this case, the reaction between the polyvinyl alcohol resin and the water-soluble epoxy resin proceeds mainly by removing the solvent.

  The primer layer can be formed by coating the primer coating solution on a retardation film and subjecting it to a drying treatment. The coating method is not particularly limited, and various known coating methods such as a direct gravure method, a reverse gravure method, a die coating method, a comma coating method, and a bar coating method can be used. The drying temperature in a drying process can be about 60-100 degreeC, for example. Prior to the application of the primer coating solution, it is preferable that the surface of the retardation film is subjected to an easy adhesion treatment such as a corona discharge treatment to improve wettability. Thereby, the adhesiveness of a primer layer and the phase difference film which consists of polypropylene resin can be improved.

  The thickness of the primer layer is preferably in the range of about 0.1 to 10 μm, more preferably about 0.5 to 10 μm.

  Here, the solvent is removed by the drying treatment to form a crosslinked cured product of the water-soluble epoxy resin and the polyvinyl alcohol resin, but the curing reaction is not necessarily complete. That is, the primer layer may consist only of a cross-linked cured product of a water-soluble epoxy resin and a polyvinyl alcohol resin, or together with the cross-linked cured product, an unreacted water-soluble epoxy resin and / or polyvinyl alcohol-based product. It may contain a resin. Even if the curing reaction does not proceed completely, sufficient adhesion can be obtained. Further, the primer layer after the drying treatment may contain some solvent (for example, water). Even in this case, sufficient adhesion can be obtained.

<Adhesive layer>
Examples of the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer (pressure-sensitive adhesive layer 40 in FIG. 1) include base polymer pressure-sensitive adhesives such as acrylic polymers, silicone polymers, polyesters, polyurethanes, and polyethers. Above all, like acrylic pressure-sensitive adhesives based on acrylic polymers, it has excellent optical transparency, moderate wettability and cohesion, and excellent adhesion to substrates. It is preferable to select and use one that has weather resistance, heat resistance, etc. 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.

  A diffusion adhesive in which a light diffusing agent is dispersed can also be used as the adhesive that forms the adhesive layer. The light diffusing agent is for imparting light diffusibility to the pressure-sensitive adhesive layer, and may be fine particles having a refractive index different from that of the base polymer constituting the pressure-sensitive adhesive layer. Fine particles made of (polymer) can be used. Since the base polymer constituting the pressure-sensitive adhesive layer including the acrylic base polymer as described above often has a refractive index of around 1.4, the refractive index of the light diffusing agent is about 1-2. What is necessary is just to select suitably. The difference in refractive index between the base polymer constituting the pressure-sensitive adhesive layer and the light diffusing agent is usually 0.01 or more, and from the viewpoint of the brightness and visibility of the image display device, it is 0.01 or more and 0.5 or less. It is preferable to do this. The fine particles used as the light diffusing agent are preferably spherical and those close to monodisperse. For example, fine particles having an average particle diameter in the range of about 2 to 6 μm are preferably used.

  Examples of the fine particles made of an inorganic compound include aluminum oxide (refractive index 1.76) and silicon oxide (refractive index 1.45).

  Examples of the fine particles made of an organic compound (polymer) include melamine beads (refractive index 1.57), polymethyl methacrylate beads (refractive index 1.49), methyl methacrylate / styrene copolymer resin beads (refractive index). 1.50), polycarbonate beads (refractive index 1.55), polyethylene beads (refractive index 1.53), polystyrene beads (refractive index 1.6), polyvinyl chloride beads (refractive index 1.46) ), Silicone resin beads (refractive index 1.46), and the like.

  The blending amount of the light diffusing agent is appropriately determined in consideration of the haze value required for the pressure-sensitive adhesive layer in which it is dispersed, the brightness of the image display device to which it is applied, etc. It is about 3-30 weight part with respect to 100 weight part of base polymers which comprise an adhesive layer.

  The haze value of the pressure-sensitive adhesive layer in which the light diffusing agent is dispersed ensures the brightness of the image display device to which the retardation film with the pressure-sensitive adhesive layer or the polarizing plate using the pressure-sensitive adhesive layer is applied. From the viewpoint of making it difficult to cause occurrence, it is preferable to be in the range of 20 to 80%. The haze value is a value represented by (diffuse transmittance / total light transmittance) × 100 (%), and is measured according to JIS K 7105.

  The pressure-sensitive adhesive layer can be formed by a method in which a pressure-sensitive adhesive solution mainly composed of the base polymer as described above is applied on the primer layer and dried. After forming the pressure-sensitive adhesive layer by applying and drying the adhesive solution, this film with the pressure-sensitive adhesive layer may also be formed by a method of bonding to the surface of the primer layer so that the pressure-sensitive adhesive layer side becomes the bonding surface Can do. The surface of the primer layer on which the pressure-sensitive adhesive layer is formed is preferably subjected to corona discharge treatment in advance. Thereby, the adhesiveness of a primer layer and an adhesive layer can be improved. In the case where an elliptically polarizing plate is produced by laminating a polarizing plate on the side opposite to the primer layer side of the retardation film (the elliptically polarizing plate will be described later), the formation of the pressure-sensitive adhesive layer is performed by the retardation film. It may be performed after laminating a polarizing plate on the substrate.

  The thickness of an adhesive layer is about 1-50 micrometers normally, Preferably it is about 5-40 micrometers. Moreover, when using the adhesive layer in which the light-diffusion agent was disperse | distributed, although the thickness of this adhesive layer is determined according to the adhesive force etc., it is about 1-40 micrometers normally. In order to obtain a thin retardation film with an adhesive layer and a polarizing plate using the same without impairing properties such as processability and durability, the thickness of the adhesive layer in which the light diffusing agent is dispersed is 3 to 3. It is preferable to be about 25 μm. Further, by setting the thickness of the pressure-sensitive adhesive layer in which the light diffusing agent is dispersed to about 3 to 25 μm, the brightness when the image display device is viewed from the front or obliquely is maintained, and the display image blurs. Blur can be made difficult to occur.

<< Ellipse Polarizing Plate >>
The retardation film with an adhesive layer of the present invention can be suitably applied to an elliptically polarizing plate. In the elliptically polarizing plate of the present invention, the retardation film with an adhesive layer may function as a quarter wavelength plate or a half wavelength plate. FIG. 2 is a schematic cross-sectional view (FIG. 2 (A)) showing a preferred example of the elliptically polarizing plate of the present invention and a schematic view (FIG. 2 (B)) for explaining the relationship between the axial angles. The elliptically polarizing plate 52 shown in FIG. 2 is obtained by laminating a linearly polarizing plate 50 on the surface opposite to the adhesive layer of the retardation film 10 with an adhesive layer (that is, on a retardation film made of polypropylene resin). Do it. In this example, the phase difference film 10 with an adhesive layer functions as a quarter wave plate. The quarter-wave plate functions to convert light that is incident as linearly polarized light into elliptically polarized light such as circularly polarized light, and light that is incident as elliptically polarized light such as circularly polarized light into linearly polarized light. Have

Here, when the retardation film with a pressure-sensitive adhesive layer of the present invention is used as a quarter-wave plate, the in-plane retardation value R ₀ is preferably in the range of 70 to 160 nm, more preferably 80 to 150 nm. More preferably, it is in the range.

  A linearly polarizing plate is an optical member provided with a function of absorbing linearly polarized light having a vibration surface in a certain direction and transmitting linearly polarized light having a vibration surface in a direction orthogonal thereto, and is generally used in this field. You can use what you have. Specifically, a polyvinyl alcohol linear polarizing plate in which a transparent protective layer is formed on at least one surface of a polarizing film made of a polyvinyl alcohol resin film is common. A function of absorbing linearly polarized light having a vibrating surface in a certain direction and transmitting linearly polarized light having a vibrating surface in a direction orthogonal to the above by adsorbing and orienting a dichroic dye on a polyvinyl alcohol resin film. Can be granted. As the dichroic dye, iodine or a dichroic organic dye is used. A polarizing film comprising a polyvinyl alcohol resin film can be obtained by subjecting the polyvinyl alcohol resin film to uniaxial stretching, dyeing with a dichroic dye, and boric acid treatment after dyeing.

  Examples of the transparent protective layer used in the linear polarizing plate include films of acetyl cellulose resins typified by triacetyl cellulose (TAC) and diacetyl cellulose, which have been conventionally used as protective layers for polarizing films. In addition, a film of a cyclic polyolefin resin represented by a norbornene resin, a film of a polypropylene resin, a film of a polyethylene terephthalate resin, a film of poly (meth) acrylate, and the like may be used.

  In the elliptically polarizing plate shown in FIG. 2 (A), with reference to FIG. 2 (B), with the absorption axis 22 of the linearly polarizing plate 50 as a reference, the counterclockwise direction is positive and a quarter wavelength plate is used. It arrange | positions so that the angle (theta) which reaches the in-plane slow axis 12 of the phase difference film 10 with an adhesive layer may be 40-50 degree | times, Preferably it is substantially 45 degree | times so that it may function as a substantially circularly-polarizing plate. Become. Or, with reference to the absorption axis 22 of the linear polarizing plate 50, the angle θ reaching the in-plane slow axis 12 of the phase difference film 10 with the pressure-sensitive adhesive layer that is a quarter-wave plate, with the counterclockwise direction being positive, Even if it is disposed at 130 to 140 degrees, preferably approximately 135 degrees, it also functions as a substantially circularly polarizing plate. Hereinafter, when the angle is expressed, the counterclockwise rotation with respect to the absorption axis is positive as in the description here.

  FIG. 3 is a schematic cross-sectional view (FIG. 3 (A)) showing another preferred example of the elliptically polarizing plate of the present invention and a schematic view (FIG. 3 (B)) for explaining the relationship between the axial angles. The elliptically polarizing plate 55 shown in FIG. 3 is on the surface opposite to the pressure-sensitive adhesive layer of the pressure-sensitive adhesive layer-equipped retardation film 10 that is a quarter-wave plate (that is, on a phase difference film made of polypropylene resin). Further, a half-wave plate 25 is laminated, and a linearly polarizing plate 50 is laminated on the half-wave plate 25. The half-wave plate 25 has a function of rotating the direction of linearly polarized light.

In the elliptically polarizing plate shown in FIG. 3, the above-mentioned ones can be used as the transparent protective layer used for the linearly polarizing plate and the linearly polarizing plate. Moreover, as a half-wave plate, a conventionally well-known thing can be used and the phase difference film with an adhesive layer of this invention may be used. When the retardation film with an adhesive layer of the present invention is used as a half-wave plate, the in-plane retardation value R ₀ is preferably in the range of 240 to 400 nm, and more preferably in the range of 260 to 330 nm. It is more preferable.

  As shown in FIG. 3A, by using a combination of a quarter-wave plate and a half-wave plate, a laminate of these wave plates has a wide wavelength range in the visible light region, that is, a wide band. An elliptical polarizing plate that functions as a quarter-wave plate and has a linear polarizing plate laminated on its half-wave plate side can convert linearly polarized light into circularly polarized light and circularly polarized light into linearly polarized light over a wide band. become. Furthermore, by comprising in this way, the angle dependence of the antireflection effect can also be reduced.

  In the elliptically polarizing plate shown in FIG. 3A, with reference to the absorption axis 22 of the linearly polarizing plate 50, the in-plane slow axis 17 of the half-wave plate 25 is referred to with reference to FIG. The reaching angle φ is 10 to 20 degrees, preferably about 15 degrees, and the in-plane retardation of the retardation film 10 with an adhesive layer that is a quarter-wave plate from the in-plane slow axis 17 of the half-wave plate 25. By arranging so that the angle Ψ reaching the axis 12 is 55 to 65 degrees, preferably approximately 60 degrees, it functions almost as a circularly polarizing plate. Alternatively, on the basis of the absorption axis 22 of the linearly polarizing plate 50, the angle φ reaching the in-plane slow axis 17 of the half-wave plate 25 is 100 to 110 degrees, preferably about 105 degrees. The angle Ψ from the in-plane slow axis 17 to the in-plane slow axis 12 of the retardation film 10 with a pressure-sensitive adhesive layer, which is a quarter wavelength plate, is 55 to 65 degrees, preferably about 60 degrees. By doing so, it will still function as a circularly polarizing plate. The latter relationship (the angle φ from the absorption axis 22 of the linear polarizing plate 50 to the in-plane slow axis 17 of the half-wave plate 25 is 100 to 110 degrees) is shown in FIG. This corresponds to a state in which “axis 22” is read as “transmission axis of linearly polarizing plate”. In the linear polarizing plate, the absorption axis and the transmission axis are in a relationship orthogonal in the plane.

  In the production of the elliptically polarizing plate, the same adhesive as that used for the above-mentioned adhesive layer can be used for laminating the wave plates (quarter wave plate and half wave plate). Moreover, the same adhesive can also be used for bonding with a wavelength plate and a linearly-polarizing plate, or an adhesive agent can also be used.

  The elliptically polarizing plate of the present invention includes a pressure-sensitive adhesive layer derived from a pressure-sensitive retardation film on the surface opposite to the linear polarizing plate (a quarter wavelength plate side). The said adhesive layer can be used suitably for bonding with a liquid crystal cell.

<< Liquid Crystal Display >>
FIG. 4 is a schematic cross-sectional view showing the configuration of an example of the liquid crystal display device of the present invention. The liquid crystal display device shown in FIG. 4 is an example in which the elliptically polarizing plate 52 shown in FIG. 2 is arranged on both sides of the liquid crystal cell 60. Specifically, the backlight 70 and the elliptically polarizing plate 52 are arranged from the backlight side. The liquid crystal cell 60 and the elliptically polarizing plate 52 are arranged in this order. The two elliptically polarizing plates 52 are bonded using the pressure-sensitive adhesive layer so that the phase difference film with pressure-sensitive adhesive layer 10 side that is a quarter wavelength plate faces the liquid crystal cell 60. The two elliptically polarizing plates 52 are arranged so that the absorption axes of the linearly polarizing plates 50 are orthogonal to each other.

  FIG. 5 is a schematic cross-sectional view showing the configuration of another example of the liquid crystal display device of the present invention. The liquid crystal display device shown in FIG. 5 is an example in which the elliptically polarizing plate 55 shown in FIG. 3 is arranged on both sides of the liquid crystal cell 60. Specifically, the backlight 70 and the elliptically polarizing plate 55 are arranged from the backlight side. The liquid crystal cell 60 and the elliptically polarizing plate 55 are arranged in this order. The two elliptically polarizing plates 55 are bonded using the pressure-sensitive adhesive layer so that the phase difference film 10 with the pressure-sensitive adhesive layer, which is a quarter wavelength plate, faces the liquid crystal cell 60. The two elliptical polarizing plates 55 are arranged so that the absorption axes of the linear polarizing plates 50 are orthogonal to each other.

  Note that the backlight 70 is provided when the liquid crystal display device is a transmissive or transflective type, and may be omitted in the case of a reflective liquid crystal display device. 4 and 5, the elliptically polarizing plate of the present invention is used on both surfaces of the liquid crystal cell. However, the present invention is not limited to this, and the elliptically polarizing plate of the present invention is used on one side of the liquid crystal cell. Another polarizing plate may be bonded to one surface.

  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 retardation film)
A propylene / ethylene random copolymer (“Sumitomo Nobrene W151” manufactured by Sumitomo Chemical Co., Ltd.) containing about 5% ethylene unit was formed into a raw film made of polypropylene resin having a thickness of 40 μm. The original film was subjected to transverse uniaxial stretching to obtain a uniaxial retardation film. This retardation film had R ₀ = 90 nm, R _th = 45 nm, and a thickness of 9 μm. Next, Toraytec 7332 manufactured by Toray Film Processing Co., Ltd. was bonded to one side of the retardation film made of polypropylene resin as a surface protective film.

(Production Example 2: Preparation of primer coating liquid I)
"Gose Pharma RZ200" manufactured by Nippon Synthetic Chemical Industry Co., Ltd. (trade name, modified polyvinyl alcohol having a saponification degree of 99.0 mol% or more) as a polyvinyl alcohol resin in 100 parts by weight of water heated to 95 ° C After adding 3 parts by weight and stirring, it was cooled to room temperature. Next, as a water-soluble epoxy resin, “Smilease Resin 650 (30)” (trade name, aqueous solution with a solid content concentration of 30%) 2.0, which is a polyamide epoxy resin manufactured by Sumika Chemtex Co., Ltd., is added to this solution. The primer coating liquid I was obtained by adding and stirring parts by weight.

(Production Example 3: Preparation of primer coating solution II)
"Gose Pharma RZ200" manufactured by Nippon Synthetic Chemical Industry Co., Ltd. (trade name, modified polyvinyl alcohol having a saponification degree of 99.0 mol% or more) as a polyvinyl alcohol resin in 100 parts by weight of water heated to 95 ° C After adding 3 parts by weight and stirring, it was cooled to room temperature. Next, as a water-soluble epoxy resin, “Smilease Resin 650 (30)” (trade name, aqueous solution having a solid content concentration of 30%) 2.5, which is a polyamide epoxy resin manufactured by Sumika Chemtex Co., Ltd., is added to this solution. A primer coating solution II was obtained by adding parts by weight and stirring.

(Production Example 4: Preparation of primer coating solution III)
"Gose Pharma RZ200" manufactured by Nippon Synthetic Chemical Industry Co., Ltd. (trade name, modified polyvinyl alcohol having a saponification degree of 99.0 mol% or more) as a polyvinyl alcohol resin in 100 parts by weight of water heated to 95 ° C After adding 3 parts by weight and stirring, it was cooled to room temperature. Next, in this solution, as a water-soluble epoxy resin, “Smilease Resin 650 (30)” (trade name, aqueous solution with a solid content concentration of 30%) 3.0, which is a polyamide epoxy resin manufactured by Sumika Chemtex Co., Ltd., 3.0 A primer coating liquid III was obtained by adding parts by weight and stirring.

(Production Example 5: Preparation of primer coating solution IV)
To 100 parts by weight of water heated to 95 ° C., as a polyvinyl alcohol-based resin, “Poval KL-318” (trade name, modified polyvinyl alcohol having a saponification degree of 85.0 to 90.0 mol%) manufactured by Kuraray Co., Ltd. ) After adding 3 parts by weight and stirring, it was cooled to room temperature. Next, as a water-soluble epoxy resin, “Smilease Resin 650 (30)” (trade name, aqueous solution having a solid content concentration of 30%) 2.5, which is a polyamide epoxy resin manufactured by Sumika Chemtex Co., Ltd., is added to this solution. A primer coating liquid IV was obtained by adding and stirring parts by weight.

(Production Example 6: Preparation of primer coating solution V)
To 100 parts by weight of water heated to 95 ° C., as a polyvinyl alcohol resin, “Poval KL-506” (trade name, modified polyvinyl alcohol having a saponification degree of 74.0 to 80.0 mol%) manufactured by Kuraray Co., Ltd. ) After adding 3 parts by weight and stirring, it was cooled to room temperature. Next, as a water-soluble epoxy resin, “Smilease Resin 650 (30)” (trade name, aqueous solution having a solid content concentration of 30%) 2.5, which is a polyamide epoxy resin manufactured by Sumika Chemtex Co., Ltd., is added to this solution. A primer coating solution V was obtained by adding and stirring parts by weight.

<Example 1>
(A) Formation of primer layer The surface of the retardation film obtained in Production Example 1 opposite to the surface on which the surface protective film is laminated is subjected to corona discharge treatment with an integrated dose of 15.9 kJ / m ^2. did. Within 5 minutes after the corona discharge treatment, the primer coating liquid I obtained in Production Example 2 was applied to the corona-treated surface using a Mayer bar (# 14), and then the surface was subjected to 15 in an oven at 80 ° C. A primer layer having a thickness of 1.2 μm was formed on the retardation film.

(B) Production of elliptically polarizing plate One of polarizing plates (SR062 manufactured by Sumitomo Chemical Co., Ltd.) in which protective films made of saponified triacetylcellulose are bonded to both surfaces of a polarizing film made of polyvinyl alcohol resin. A urethane acrylate pressure-sensitive adhesive (NS300MP sold by Lintec Corporation) was applied to the surface to obtain a polarizing plate with an adhesive layer. Next, after peeling off the surface protective film of the retardation film having the primer layer, the peeled surface is subjected to corona discharge treatment with an integrated irradiation amount of 15.9 kJ / m ² , and within 5 minutes after the corona discharge treatment, The said polarizing plate with an adhesive layer was bonded to the corona treatment surface so that an adhesive layer might become a bonding surface. Next, the surface of the primer layer of the obtained polarizing plate with retardation film was subjected to corona discharge treatment with an integrated dose of 15.9 kJ / m ² , and then within 5 minutes after the corona discharge treatment, An acrylic pressure-sensitive adhesive (P3132 sold by Lintec Corporation) was bonded to obtain an elliptical polarizing plate with a pressure-sensitive adhesive layer.

<Example 2>
After forming a primer layer having a thickness of 1.2 μm on the retardation film obtained in Production Example 1 using the primer coating liquid II obtained in Production Example 3, the same as in Example 1, An elliptically polarizing plate with an adhesive layer was produced.

<Example 3>
After forming a primer layer having a thickness of 1.2 μm on the retardation film obtained in Production Example 1 using the primer coating liquid III obtained in Production Example 4, the same as in Example 1, An elliptically polarizing plate with an adhesive layer was produced.

<Comparative Example 1>
After forming a primer layer having a thickness of 1.2 μm on the retardation film obtained in Production Example 1 using the primer coating liquid IV obtained in Production Example 5, An elliptically polarizing plate with an adhesive layer was produced.

<Comparative example 2>
After forming a primer layer having a thickness of 1.2 μm on the retardation film obtained in Production Example 1 using the primer coating liquid V obtained in Production Example 6, the same as in Example 1, An elliptically polarizing plate with an adhesive layer was produced.

<Comparative Example 3>
The surface of the retardation film obtained in Production Example 1 opposite to the side on which the surface protective film was laminated was subjected to corona discharge treatment at an integrated irradiation amount of 15.9 kJ / m ² . Within 5 minutes after corona discharge treatment, an acrylic pressure-sensitive adhesive (P3132 sold by Lintec Corporation) is bonded to the corona-treated surface to obtain a phase difference film with a pressure-sensitive adhesive layer (no primer layer). It was.

Next, urethane acrylate is applied to one surface of a polarizing plate (SR062 manufactured by Sumitomo Chemical Co., Ltd.) in which protective films made of saponified triacetylcellulose are bonded to both surfaces of a polarizing film made of polyvinyl alcohol resin. A system pressure-sensitive adhesive (NS300MP sold by Lintec Corporation) was applied to obtain a polarizing plate with an adhesive layer. Next, after peeling off the surface protective film of the above retardation film with pressure-sensitive adhesive layer, the peeled surface was subjected to corona discharge treatment at an integrated irradiation amount of 15.9 kJ / m ² , and within 5 minutes after corona discharge treatment, The pressure-sensitive adhesive layer-attached polarizing plate was bonded to the corona-treated surface so that the pressure-sensitive adhesive layer became a bonding surface, and an adhesive layer-attached elliptical polarizing plate was obtained.

  About the elliptically polarizing plate with an adhesive layer of the said Example and comparative example, the thickness was measured using the digital length measuring instrument "MH-15M" by Nikon Corporation. The results are shown in Table 1. Moreover, the following test was done in order to evaluate the adhesiveness of an adhesive layer and retardation film, and the peelability of the adhesive layer bonded by the glass plate.

(1) Throwing force test After subjecting the primer layer surface of the retardation film with a primer layer obtained in Example 1 and Comparative Examples 1 and ² to corona discharge treatment with an integrated irradiation amount of 15.9 kJ / m ² , corona Within 5 minutes after the discharge treatment, an acrylic pressure-sensitive adhesive (P3132 sold by Lintec Corporation) was bonded to the corona-treated surface to prepare a phase difference film with a pressure-sensitive adhesive layer. Next, after peeling the surface protective film of the said phase difference film with an adhesive layer, the corona discharge process was given to the peeling surface with the integrated irradiation amount of 15.9 kJ / m < ² >. On the other hand, a corona discharge treatment was performed on one side of a biaxial thermoplastic saturated norbornene resin film (ZB0555124 manufactured by Nippon Zeon Co., Ltd.) under the condition of an integrated dose of 15.9 kJ / m ² . Next, within 10 minutes after the corona discharge treatment, an active energy ray-curable resin composition containing an epoxy compound is used on the corona-treated surface of the biaxial thermoplastic saturated norbornene resin film by using a Mayer bar (# 1). The thing was coated. Next, the coated surface and the corona-treated surface of the retardation film with a pressure-sensitive adhesive layer are bonded together and UV-cured at 500 mW / 1500 mJ with a UV irradiation device manufactured by FUSION, and then a temperature of 23 ° C. and a relative humidity of 60%. The film for evaluation was produced by leaving it to stand for 1 day in the atmosphere. This evaluation film has a configuration of thermoplastic saturated norbornene resin film / cured product layer of curable resin composition / retardation film / primer layer / adhesive layer.

  Next, this evaluation film was cut into a width of 25 mm and a length of about 200 mm, and three points of adhesion were measured in the length direction using “Adhesion Strength Evaluator” manufactured by Nippon System Group Co., Ltd. The measurement is performed by attaching styrene rubber having a hardness of 60 degrees to the pressure-sensitive adhesive layer and peeling the pressure-sensitive adhesive layer from the retardation film when slid 20 times from a certain direction while pressing with a pressure of 0.4 MPa. The three-point average of the measured lengths was obtained as the peel distance. The measurement was performed in an atmosphere at a temperature of 23 ° C. and a relative humidity of 60%. For Comparative Example 3, an evaluation film having the same configuration as described above was prepared and measured using a phase difference film with an adhesive layer having no primer layer. The results are shown in Table 1.

(2) Glass plate adhesion peeling test The evaluation film used in the anchoring force test was cut into a width of 25 mm and a length of about 200 mm, and the pressure-sensitive adhesive layer surface was bonded to soda glass, and then the pressure in the autoclave was 5 kgf / The pressure treatment was performed at cm ² and a temperature of 50 ° C. for 20 minutes, and left for 1 day in an atmosphere of a temperature of 23 ° C. and a relative humidity of 60%. Next, using a universal tensile tester (AG-1, manufactured by SHIMAZU Co., Ltd.), in an atmosphere of a temperature of 23 ° C. and a relative humidity of 60%, a crosshead speed (peeling speed) of 200 mm / min and a 90 ° peel By the test, the sample for evaluation was peeled from the glass plate, and the peelability was evaluated. The results are summarized in Table 1. The evaluation criteria are as follows.
A: The adhesive was able to be peeled off without remaining on the glass plate.
B: A large amount of adhesive remained on the glass plate.

  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 a preferable example of the phase difference film with an adhesive layer of this invention. It is the schematic for demonstrating the cross-sectional schematic diagram which shows a preferable example of the elliptically polarizing plate of this invention, and its axial angle. It is the schematic for demonstrating the cross-sectional schematic diagram which shows another preferable example of the elliptically polarizing plate of this invention, and its axial angle. It is a cross-sectional schematic diagram which shows a structure of an example of the liquid crystal display device of this invention. It is a cross-sectional schematic diagram which shows the structure of another example of the liquid crystal display device of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Retardation film with adhesive layer, 12 1/4 wavelength plate in-plane slow axis, 17 1/2 wavelength plate in-plane slow axis, 20 retardation film, 22 absorption axis, 25 1/2 wavelength plate , 30 primer layer, 40 pressure-sensitive adhesive layer, 50 linearly polarizing plate, 52, 55 elliptically polarizing plate, 60 liquid crystal cell, 70 backlight.

Claims (6)

A phase difference film made of a polypropylene resin,
A primer layer laminated on one surface of the retardation film ;
An adhesive layer laminated on the surface opposite to the retardation film side of the primer layer, made of,
The said primer layer is a phase difference film with an adhesive layer containing a water-soluble epoxy resin and the polyvinyl alcohol-type resin whose saponification degree is 95.0 mol% or more. The retardation film is made of a copolymer of propylene and ethylene,
The retardation film with a pressure-sensitive adhesive layer according to claim 1, wherein the content of the structural unit derived from ethylene is 10% by weight or less.   The said phase difference film is a quarter wavelength plate, The phase difference film with an adhesive layer of Claim 1 or 2.   The elliptically polarizing plate by which a polarizing plate is laminated | stacked on the said retardation film in the retardation film with an adhesive layer in any one of Claims 1-3.   The elliptically polarizing plate according to claim 4, further comprising a half-wave plate between the retardation film and the polarizing plate.   A liquid crystal cell and the elliptically polarizing plate according to claim 4 or 5 laminated on one or both sides of the liquid crystal cell, wherein the elliptically polarizing plate has a pressure-sensitive adhesive layer-attached retardation film side facing the liquid crystal cell. And a liquid crystal display device bonded to the liquid crystal cell using the pressure-sensitive adhesive layer.

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