JP2003207624A - Circularly polarizing plate and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an obliquely oriented long circularly polarizing plate excel lent in durability, further realizing circularly polarized light in a wide wave length region and also improving a yield. <P>SOLUTION: The long circularly polarizing plate comprises a polarizing film with an absorption axis neither parallel nor vertical to a longitudinal direction coated with at least a sheet of an optical film on at least a surface thereof, further has an adhesive layer on at least an outside of the polarizing film or the optical film and has ≥10° and <90° angle between an absorption axis of the polarizing film and a slow axis of at least a sheet of the optical film, has the ratio of transmittance in a direction parallel to a transmission axis to that in a direction vertical to the transmission axis satisfying an inequality (I) when light of 450 nm wavelength is made incident on the circularly polarizing plate from the polarizing film side after a durability test and further the ratio of the transmittance in the direction parallel to the transmission axis to that in the direction vertical to the transmission axis satisfying an inequality (II) when light of 590 nm wavelength is made incident thereon from the polarizing film side. (I) 0.95<T||(450)/T⊥(450)≤1.05, (II) 0.95<T||(590)/T⊥(590)≤1.05. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a circularly polarizing plate which is excellent in durability and yield and realizes circularly polarized light over the entire incident visible light, and a liquid crystal display device using the same which has high display quality.

[0002]

2. Description of the Related Art A polarizing plate is a liquid crystal display device (hereinafter, LCD).
With the spread of, the demand is rapidly increasing. Polarizing plates are generally
An optical film such as a protective film, a surface protective film, a retardation film (λ / 4 plate, λ / 2 plate) or the like is attached to both sides or one side of a polarizing film having a polarizing ability through an adhesive layer or an adhesive layer. Is used. Further, the polarizing plate is usually provided with an adhesive layer on the outside of at least one of the optical film and the polarizing film, and is used by being adhered to another member such as a liquid crystal display device via the adhesive layer.

Polyvinyl alcohol (hereinafter referred to as PVA) is mainly used as a material for the polarizing film. The PVA film is uniaxially stretched and then dyed with iodine or a dichroic dye, or dyed and then stretched. Further, a polarizing film is formed by further crosslinking with a boron compound. Since the polarizing film is usually produced by stretching (longitudinal stretching) along the running direction (longitudinal direction) of the continuous film, the absorption axis of the polarizing film is substantially parallel to the longitudinal direction.

On the other hand, the protective film attached to at least one surface of the polarizing film has a low retardation because it changes the polarization state when it has a birefringence. However, since there is still a problem that the retardation increases depending on the ambient temperature and humidity, conventionally, the slow axis of the protective film and the transmission axis of the polarizing film should be perpendicular (that is, the slow axis of the protective film and the polarization axis should be It was taken as a countermeasure by adhering so that the absorption axes of the film are parallel. However, in this case, since the slow axis of the protective film and the absorption axis of the polarizing film are parallel to each other, the dimensional stability is poor, and it has been found that there is a problem in terms of temporal stability. That is, it was found that in the conventional case, the contraction of the polarizing film caused the contraction of the protective film in the same direction, and the force was supported by the adhesive layer, but the contraction of the polarizing film could not be sufficiently suppressed. Further, the λ / 4 plate has many uses related to the antireflection film and the liquid crystal display device, and is attached so that the optical axis of the λ / 4 plate intersects the optical axis of the polarizing film. Have been combined.

On the other hand, in the conventional LCD, since the transmission axis of the polarizing plate is inclined by 45 ° with respect to the longitudinal or lateral direction of the screen, the polarizing film is longitudinally or laterally stretched as described above. In the process of punching a polarizing plate manufactured in the roll form, it was manufactured in the longitudinal direction of the roll.
It was necessary to punch in the 5 ° direction. In this case, there is a problem that the yield becomes small, or the polarizing plate after the combination is difficult to reuse the material, and as a result, the amount of waste increases. There has been proposed a method of obtaining a polarizing film by inclining the orientation axis of a polymer at a desired angle (JP 2000-9912 A, JP 3-182701 A). However, although a polarizing film having an absorption axis that is not parallel to the longitudinal direction can be theoretically obtained by any of these methods, in both cases, when the plastic film is stretched, the film traveling speed changes depending on the left and right of the film. Since cracks and wrinkles occur, it is very difficult to produce a polarizing film having a desired inclination angle (45 ° in a polarizing plate), and it has not been put to practical use.

[0006]

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above-mentioned various problems of the prior art. That is, an object of the present invention is to provide an obliquely oriented long circular polarizing plate which is excellent in durability, realizes circularly polarized light in a wide wavelength range, and can improve the yield. A further object of the present invention is excellent durability,
Another object of the present invention is to provide a circularly polarizing plate with a protective film, which can realize circularly polarized light in a wide wavelength range. A further object of the present invention is to provide a method for manufacturing the above circularly polarizing plate. A further object of the present invention is to provide a reflective liquid crystal display device which corrects the deviation of the degree of circular polarization on the short wavelength side and uses a circular polarizing plate of high display quality without color deviation.

[0007]

It has been found that the above object of the present invention can be achieved by the following constitution. 1) A long circle in which at least one optical film is coated on at least one surface of a polarizing film whose absorption axis is neither parallel nor perpendicular to the longitudinal direction, and which has an adhesive layer on the outside of at least one polarizing film or the optical film. A polarizing plate, wherein an angle between an absorption axis of the polarizing film and a slow axis of at least one optical film is 10 ° or more and less than 90 °, and the circular polarizing plate is irradiated with light of 450 nm after a durability test. The ratio of the transmittance in the direction parallel to the transmission axis when incident from the side to the transmittance in the direction perpendicular to the transmission axis satisfies the following formula (I).
A circle characterized in that the ratio of the transmittance in the direction parallel to the transmission axis and the transmittance in the direction perpendicular to the transmission axis when 0 nm light is incident from the polarizing film side satisfies the following formula (II). Polarizer. (I) 0.95 <T // (450) / T⊥ (450) ≦
1.05 (II) 0.95 <T // (590) / T⊥ (590) ≦
1.05 [wherein T // (450) is the transmittance in the direction parallel to the transmission axis when 450 nm light is incident from the polarizing film side;
T⊥ (450) is the transmittance in the direction perpendicular to the transmission axis when 450 nm light is incident from the polarizing film side; T //
(590) is the transmittance in the direction parallel to the transmission axis when light of 590 nm is incident from the polarizing film side; and T⊥
(590) is the transmittance in the direction perpendicular to the transmission axis when light of 590 nm is incident from the polarizing film side].

2) A circularly polarizing plate in which at least one protective film is coated on at least one surface of a polarizing film, and an adhesive layer is provided on the outer side of at least one polarizing film or the protective film, the absorption axis of the polarizing film. And the slow axis of the protective film form an angle of 10 °
The angle is not less than 90 °, and after the durability test, 4
The ratio of the transmittance in the direction parallel to the transmission axis and the transmittance in the direction perpendicular to the transmission axis when light of 50 nm is incident from the polarizing film side satisfies the above formula (I), and light of 590 nm A circularly polarizing plate, characterized in that the ratio of the transmittance in the direction parallel to the transmission axis and the transmittance in the direction perpendicular to the transmission axis when the light enters from the polarizing film side satisfies the above formula (II).

3) A polarizing film is produced by holding both ends of a continuously supplied polymer film by holding means, and applying tension while stretching the holding means while advancing in the longitudinal direction of the film, Further, from the substantial holding start point of one end of the polymer film to the substantial holding release point L1 of the holding means and the other holding end of the polymer film from the substantial holding start point to the substantial holding release point. The locus L2 of the holding means and the distance W between the two substantial holding release points satisfy the following expression (1), and the difference in the transport speed in the longitudinal direction between the left and right film holding means is less than 1%. The method for producing a circularly polarizing plate according to 1) or 2) above. Formula (1) | L2-L1 |> 0.4W

4) Further, on at least one surface of the polarizing film,
The method for producing a circularly polarizing plate as described in 3) above, wherein at least one optical film having a slow axis parallel to the longitudinal direction is continuously laminated.

5) A circularly polarizing plate obtained by cutting out the long circularly polarizing plate described in 1) above to at least one of the polarizing plates arranged on both sides of the liquid crystal cell or the circularly polarized light described in 2) above. A liquid crystal display device characterized in that a plate is adhered and used.

In the circularly polarizing plate of the present invention, as described above, since the absorption axis of the polarizing film and the slow axis of the optical film intersect with each other, the polarization generated in the direction along the absorption axis of the polarizing film. The shrinkage of the film is effectively suppressed by the presence of the optical film whose optical axes intersect, and even if the pressure-sensitive adhesive layer has a relatively low shrinkage relaxation force, the presence of the pressure-sensitive adhesive layer causes sufficient shrinkage of the polarizing film. It was found that it could be suppressed. Furthermore, in the long circular polarizing plate of the present invention, since the absorption axis of the polarizing film is neither parallel nor perpendicular to the longitudinal direction (such a long polarizing plate may be simply referred to as “obliquely oriented” polarizing plate hereinafter). is there),
The yield in the punching process can be dramatically improved.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in more detail below. The circularly polarizing plate of the present invention comprises a polarizing film having a polarizing ability, and at least one optical film is provided on both sides or one side of the polarizing film via an adhesive layer or an adhesive layer. There is. Here, the optical film of the present invention refers to a film necessary for exhibiting the performance as a circularly polarizing plate. Specifically, it means a surface protective film, a protective film, and a retardation film. The retardation film is not particularly limited as long as it can give circularly polarized light characteristics by being overlapped with a linear polarizing plate. Further, as the surface protection film, a hard coat layer, an AG layer, an AR
Layers, CV layers and the like, and two or more of these may be used in combination. It should be noted that the slow axis of at least one of the plurality of two or more kinds of optical films may intersect with the absorption axis of the polarizing film as described above.

Usually, a circularly polarizing plate is produced by producing a long circularly polarizing plate (usually in roll form) and punching it out according to the intended use to obtain a circularly polarizing plate for practical use. Unless otherwise specified, the “circular polarizing plate” in the present invention is used to include both a long circular polarizing plate and the punched circular polarizing plate. In the present invention, the angle formed by the longitudinal direction of the long circularly polarizing plate and the absorption axis direction of the polarizing film is freely set within the range of 10 ° or more and less than 90 °, and therefore, it is combined with other optical members. The appropriate angle can be easily selected even when used.

The long circularly polarizing plate of the present invention is as described above.
The absorption axis is neither parallel nor perpendicular to the longitudinal direction (that is, obliquely oriented). Specifically, in FIG. 1, a circularly polarizing plate in which an optical film 70 having a slow axis 71 is bonded to at least one surface of a polarizing film 80 having an absorption axis 81 via an adhesive layer 75 as necessary. 85
In, the angle θ between the absorption axis 81 of the polarizing film and the stretching axis 71 of the optical film (that is, the dotted line 71 ') is 10 ° or more and less than 90 °. Within this range, excellent durability can be obtained. The angle formed by the longitudinal direction of the long circularly polarizing plate and the absorption axis direction is preferably 20 ° to 70 °, more preferably 40 ° to 50 °, and particularly preferably 44 to 46 °. Thereby, by punching the polarizing plate as shown in FIG. 2, the yield in the polarizing plate punching step can be significantly improved.

Here, regarding the angle between the absorption axis of the polarizing film and the slow axis of the optical film, the absorption axis of the polarizing film and the slow axis of the optical film are separated by separating the optical film of the circularly polarizing plate from the polarizing film. The angle formed by the absorption axis and the slow axis can be estimated by measuring Further, the absorption axis of the polarizing film is set in the axial direction that gives the maximum transmission density when the polarizing plate is overlapped with the polarizing plate whose absorption axis is known in the crossed Nicols state.
The slow axis of the optical film is the axial direction that gives the maximum refractive index by measuring the refractive index in the plane of the optical film. The angle between the absorption axis of the polarizing film and the slow axis of the optical film is an angle formed by the axial directions, and is preferably 10 ° or more and less than 90 °. The transmission density of the polarizing film is measured by a transmission densitometer (for example, X Rite.310T equipped with a status M filter).
R), and the refractive index of the protective film can be measured with an ellipsometer (for example, ellipsometer AEP-10 manufactured by Shimadzu Corporation).

Further, in the case where the optical film in which the absorption axis of the polarizing film intersects with the slow axis thereof is a protective film, the slow axis 71 of the protective film 70 in FIG. 1 is the longitudinal direction 82 of the polarizing plate. Alternatively, the absorption axis 81 of the polarizing film 80 is parallel to the lateral direction 83, and is preferably 20 ° to 70 °, more preferably 40 ° with respect to the longitudinal direction 82 of the polarizing plate or the lateral direction 83.
It is in the range of 50 to 50 °, particularly preferably 44 to 46 °. Most preferably, as shown in FIG. 2, a roll formed by laminating a protective film having a slow axis 71 parallel to the longitudinal direction on at least one surface of a polarizing film having an absorption axis 81 at about 45 ° in the longitudinal direction 82. By using a polarizing plate having a shape, a polarizing plate can be obtained with high efficiency.

The circularly polarizing plate of the present invention has a single plate transmittance of 35% or more at 550 nm and a polarization degree of 80 at 550 nm.
% Or more is preferable. The single plate transmittance is preferably 40% or more, and the polarization degree is preferably 95.0% or more, more preferably 99% or more, and particularly preferably 99.
It is 9% or more. In the present invention, unless otherwise specified, the transmittance is the single plate transmittance. The circularly polarizing plate of the present invention has excellent single-plate transmittance and polarization degree, and thus is advantageous because it can enhance the contrast when used as a liquid crystal display device.

The circularly polarizing plate of the present invention comprises at least one optical film and one polarizing film, and the slow axis of the optical film and the absorption axis of the polarizing film are 10 ° or more and less than 90 °. It is located in. Transmittance in the direction parallel to the transmission axis (T // (450)) when light of 450 nm is incident from the polarizing film side of the circularly polarizing plate of the present invention and transmittance in the direction perpendicular to the transmission axis (T⊥) The ratio of (450)) satisfies the following formula (I). (I) 0.95 ≦ T // (450) / T⊥ (450) ≦
1.05 Further 0.98 ≦ T // (450) / T⊥ (450) ≦
It is preferably 1.02.

The transmittance (T // (590)) in the direction parallel to the transmission axis when 590 nm light is incident from the polarizing film side.
And the transmittance (T⊥ (590)) in the direction perpendicular to the transmission axis satisfies the following formula (II). (II) 0.95 ≦ T // (590) / T⊥ (590) ≦
1.05 Further 0.98 ≦ T // (590) / T⊥ (590) ≦
It is preferably 1.02.

When one optical film is made to function as a λ / 4 plate, the retardation value (Re (450)) measured at a wavelength of 450 nm is 100 to 125 nm, and the retardation value (Re (450) measured at a wavelength of 590 nm ( It is preferable that Re (590)) is 120 to 160 nm and that the relationship of Re (590) -Re (450) ≧ 2 nm is satisfied. Re (590) -Re (4
50) ≧ 5 nm is more preferable, and Re (5
Most preferably, 90) -Re (450) ≧ 10 nm. The retardation value (Re (450)) measured at a wavelength of 450 nm is 108 to 120 nm, and the retardation value (Re (5) measured at a wavelength of 550 nm.
50)) is 125 to 142 nm and has a wavelength of 590 n.
Retardation value (Re (590)) measured in m is 130 to 152 nm, and Re (590)
It is preferable to satisfy the relationship of −Re (550) ≧ 2 nm. More preferably, Re (590) -Re (550) ≧ 5 nm, and Re (590) -Re (55
Most preferably, 0) ≧ 10 nm. Also, Re
It is also preferable that (550) -Re (450) ≧ 10 nm.

When one optical film is made to function as a λ / 2 plate, the retardation value (Re (450)) measured at a wavelength of 450 nm is 200 to 250 nm and the retardation value measured at a wavelength of 590 nm. (Re (590)) is 240 to 320 nm,
Then, the relationship of Re (590) −Re (450) ≧ 4 nm is satisfied. Re (590) -Re (450) ≧ 10
nm is more preferable, and Re (590) -R is more preferable.
It is most preferable that e (450) ≧ 20 nm. Retardation value (Re (45
0)) is 216 to 240 nm and has a wavelength of 550 nm.
The retardation value (Re (550)) measured by
50 to 284 nm, and the retardation value (Re (590)) measured at a wavelength of 590 nm is 260 to 3
04 nm and Re (590) -Re (55
It is preferable to satisfy the relationship of 0) ≧ 4 nm. Re
More preferably, (590) -Re (550) ≧ 10 nm, and Re (590) -Re (550) ≧ 20.
Most preferably, it is nm. In addition, Re (550)
It is also preferable that —Re (450) ≧ 20 nm.

The retardation value (Re) is calculated according to the following formula. During retardation _{(Re) = (n x -n} y) × d expression, n _x is an slow axis direction of the refractive index in the plane of the retarder (maximum refractive index in the plane); n _y Is the refractive index in the direction perpendicular to the in-plane slow axis of the retardation plate; d is the thickness (nm) of the retardation plate.

It is preferable that one optical film satisfies the following formula. 1 ≦ (n _x −n _z ) / (n _x −n _y ) ≦ 2 where n _x is the in-plane refractive index of the retardation plate in the slow axis direction; n _y is the retardation plate Is the index of refraction in the direction perpendicular to the in-plane slow axis; and _nz is the index of refraction in the thickness direction.

<Optical Film> An optical film having the above optical properties can be produced by the polymer film and method described below.

(Retardation Film) As the retardation film used in the present invention, a birefringent film having a large retardation described in, for example, JP-A-5-27118 and 5-27119, and a retardation film. Is a retardation plate in which a birefringence film having a small value is laminated so that their optical axes are orthogonal to each other. In this case, the difference in retardation between the two films is λ / over the entire visible light range.
If it is 4, the retardation plate theoretically functions as a λ / 4 plate over the entire visible light region. In addition, JP-A-10-6
A polymer film having a λ / 4 at a specific wavelength described in Japanese Patent No. 8816 and a polymer film having a λ / 2 at the same wavelength made of the same material are laminated to obtain a λ / in a wide wavelength range. 4 or a retardation plate capable of achieving λ / 4 in a wide wavelength range by laminating two polymer films described in JP-A-10-90521 can be used.

Further, according to the present invention, Japanese Patent Laid-Open No. 2000-13.
It is possible to use a retardation plate described in Japanese Patent No. 7116 and WO00 / 26705, in which the retardation is smaller as the measurement wavelength is shorter. The technique of using one retardation film is preferable in that the manufacturing process can be simplified, but it has also been found that circularly polarized light is insufficient. Therefore, in the present invention, further, in the case where a single retardation film is formed on both sides or one side of a polarizing film having a polarizing ability via an adhesive layer or a pressure-sensitive adhesive layer,
By correcting the deviation of the degree of circular polarization on the short wavelength side, which occurs when the slow axis is attached to the absorption axis of the polarizing film at an angle of 10 ° or more and less than 90 °, a retardation increasing agent is used. It is preferable to obtain a circularly polarizing plate having a wide wavelength range. This is because the contrast level was not sufficient in the conventional reflective liquid crystal display device using the retardation plate. The reason for this is that when incident light passes through the polarizing plate and the λ / 4 film, the degree of circular polarization on the short wavelength side. It is based on the finding that it is because of deviation.

(Polymer film for retardation film) It is preferable to use a polymer film having a light transmittance of 80% or more. The polymer film used in the present invention is preferably a polymer film in which birefringence is difficult to be expressed by an external force,
Examples thereof include cellulosic polymers such as triacetyl cellulose and diacetyl cellulose, norbornene polymers such as Arton and Zeonex, and polymethylmethacrylate. Cellulose ester is particularly preferable, and lower fatty acid ester of cellulose is more preferable. Lower fatty acid has 6 carbon atoms
The following fatty acids are meant. The number of carbon atoms is preferably 2 (cellulose acetate), 3 (cellulose propionate) or 4 (cellulose butyrate).
Cellulose acetate is particularly preferred. Mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate may also be used. Also,
Even known polymers such as polycarbonate and polysulfone that easily exhibit birefringence are WO00 / 2.
It is also possible to use the molecule described in 6705 or the molecule whose expression is reduced by modification.

As the polymer film for retardation film, it is preferable to use cellulose acetate having an acetylation degree of 57.0 to 61.5%. The acetylation degree means the amount of bound acetic acid per unit weight of cellulose. The degree of acetylation is
According to the measurement and calculation of the degree of acetylation in ASTM: D-817-91 (testing method for cellulose acetate, etc.). The viscosity average degree of polymerization (DP) of cellulose ester is
It is preferably 250 or more, more preferably 290 or more. The cellulose ester used in the present invention preferably has a narrow molecular weight distribution of Mw / Mn (Mw is a weight average molecular weight and Mn is a number average molecular weight) by gel permeation chromatography. The specific value of Mw / Mn is preferably 1.0 to 1.7, more preferably 1.3 to 1.65, and most preferably 1.4 to 1.6. preferable.

In order to improve the adhesion between the polymer film and the layer (adhesive layer, alignment film, or optically anisotropic layer) provided thereon, the polymer film is subjected to a surface treatment (eg, surface treatment).
Glow discharge treatment, corona discharge treatment, ultraviolet treatment, flame treatment) may be carried out. These polymer films are
It is preferable to include an ultraviolet absorber or the like. In addition, JP-A-7
An adhesive layer (undercoat layer) may be provided on the polymer film as described in JP-A-333433. The thickness of the adhesive layer is preferably 0.1 μm to 2 μm,
More preferably, it is 0.2 μm to 1 μm.

(Retardation Control) In order to adjust the retardation of the polymer film for retardation film, a method of applying an external force such as stretching is generally used.
An aromatic compound having at least two aromatic rings as described in No. 911656A2 can also be used as a retardation increasing agent. The aromatic compound is
0.01 to 100 parts by mass of cellulose acetate
It is used in the range of 20 to 20 parts by mass. The aromatic compound is preferably used in an amount of 0.05 to 15 parts by mass with respect to 100 parts by mass of cellulose acetate,
It is more preferable to use in the range of 10 to 10 parts by mass. You may use together two or more types of aromatic compounds.

The aromatic ring of the aromatic compound contains an aromatic heterocycle in addition to the aromatic hydrocarbon ring. The aromatic hydrocarbon winding is particularly preferably a 6-membered ring (that is, a benzene ring). The aromatic heterocycle is generally an unsaturated heterocycle. The aromatic heterocycle is preferably a 5-membered ring, a 6-membered ring or a 7-membered ring, more preferably a 5-membered ring or a 6-membered ring. The aromatic heterocycle generally has the largest number of double bonds. As the hetero atom, a nitrogen atom, an oxygen atom and a sulfur atom are preferable, and a nitrogen atom is particularly preferable. Examples of the aromatic hetero ring are a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, an isoxazole ring, a thiazole ring, an isothiazole ring, an imidazole ring, a pyrazole ring, a furazan ring, a triazole ring, a pyran ring and a pyridine ring. , A pyridazine ring, a pyrimidine ring, a pyrazine ring and a 1,3,5-triazine ring.

As the aromatic ring, a benzene ring, a furan ring, a thiophene ring, a pyrrole ring, an oxazole ring, a thiazole ring, an imidazole ring, a triazole ring, a pyridine ring, a pyrimidine ring, a pyrazine ring and a 1,3,5-triazine ring. Is preferred. The number of aromatic rings contained in the aromatic compound is preferably from 2 to 20, more preferably from 2 to 12, further preferably from 2 to 8, and most preferably from 3 to 6. . Also,
It is preferable to have at least one 1,3,5-triazine ring as an aromatic ring.

The bonding relationship between two aromatic rings can be classified into (a) forming a condensed ring, (b) directly connecting with a single bond, and (c) connecting via a linking group (aromatic). Because of the ring, spiro bonds cannot be formed). The connection relation may be any of (a) to (c).

Examples of the condensed ring of (a) (condensed ring of two or more aromatic rings) include indene ring, naphthalene ring, azulene ring, fluorene ring, phenanthrene ring, anthracene ring, acenaphthylene ring, naphthacene ring, Pyrene ring, indole ring, isoindole ring, benzofuran ring, benzothiophene ring, indolizine ring, benzoxazole ring, benzothiazole ring, benzimidazole ring, benzotriazole ring, purine ring, indazole ring, chromene ring, quinoline ring, isoquinoline Ring, quinolidine ring, quinazoline ring, cinnoline ring, quinoxaline ring, phthalazine ring, pteridine ring, carbazole ring, acridine ring,
A phenanthridine ring, a xanthene ring, a phenazine ring, a phenothiazine ring, a phenoxathiine ring, a phenoxazine ring and a thianthrene ring are included. A naphthalene ring, an azulene ring, an indole ring, a benzoxazole ring, a benzothiazole ring, a benzimidazole ring, a benzotriazole ring and a quinoline ring are preferable.

The single bond (b) is preferably a bond between carbon atoms of two aromatic rings. Two or more single bonds may combine two aromatic rings to form an aliphatic ring or a non-aromatic heterocycle between the two aromatic rings.

The linking group (c) is also preferably bonded to carbon atoms of two aromatic rings. The linking group is an alkylene group, an alkenylene group, an alkynylene group, -CO-, -O.
It is preferably-, -NH-, -S- or a combination thereof. Examples of linking groups composed of combinations are shown below. Note that the left-right relationship in the following examples of the linking group may be reversed.

C1: -CO-O- c2: -CO-NH- c3: -alkylene-O- c4: -NH-CO-NH- c5: -NH-CO-O- c6: -O-CO-O -C7: -O-alkylene-O-c8: -CO-alkenylene-c9: -CO-alkenylene-NH-c10: -CO-alkenylene-O-c11: -alkylene-CO-O-alkylene-O-C
O-alkylene-c12: -O-alkylene-CO-O-alkylene-O
-CO-alkylene-O-c13: -O-CO-alkylene-CO-O-c14: -NH-CO-alkenylene-c15: -O-CO-alkenylene-

The aromatic ring and the linking group may have a substituent. Examples of the substituent include a halogen atom (F, C
1, Br, I), hydroxyl, carboxyl, cyano, amino, nitro, sulfo, carbamoyl, sulfamoyl, ureido, alkyl group, alkenyl group, alkynyl group, aliphatic acyl group, aliphatic acyloxy group, alkoxy group, alkoxycarbonyl group , Alkoxycarbonylamino group, alkylthio group, alkylsulfonyl group, aliphatic amide group, aliphatic sulfonamide group, aliphatic substituted amino group, aliphatic substituted carbamoyl group, aliphatic substituted sulfamoyl group, aliphatic substituted ureido group and non-aromatic An aromatic heterocyclic group is included.

The number of carbon atoms in the alkyl group is preferably 1-8. A chain alkyl group is preferable to a cyclic alkyl group, and a straight chain alkyl group is particularly preferable.
The alkyl group may further have a substituent (eg, hydroxy, carboxy, alkoxy group, alkyl-substituted amino group). Examples of alkyl groups (including substituted alkyl groups) include methyl, ethyl, n-butyl, n-hexyl, 2
-Hydroxyethyl, 4-carboxybutyl, 2-methoxyethyl and 2-diethylaminoethyl. The alkenyl group preferably has 2 to 8 carbon atoms. A chain alkenyl group is preferable to a cyclic alkenyl group, and a straight chain alkenyl group is particularly preferable.
The alkenyl group may further have a substituent. Examples of alkenyl groups include vinyl, allyl and 1-hexenyl. The alkynyl group preferably has 2 to 8 carbon atoms. A chain alkynyl group is preferable to a cyclic alkynyl group, and a straight chain alkynyl group is particularly preferable. The alkynyl group may further have a substituent. Examples of alkynyl groups include ethynyl, 1-butynyl and 1-hexynyl.

The number of carbon atoms of the aliphatic acyl group is 1 to 1
It is preferably 0. Examples of the aliphatic acyl group include acetyl, propanoyl and butanoyl. The number of carbon atoms of the aliphatic acyloxy group is preferably 1-10. Examples of the aliphatic acyloxy group include acetoxy. The number of carbon atoms of the alkoxy group is preferably 1-8. The alkoxy group may further have a substituent (eg, an alkoxy group). Examples of alkoxy groups (including substituted alkoxy groups) include methoxy, ethoxy, butoxy and methoxyethoxy. The alkoxycarbonyl group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonyl group include methoxycarbonyl and ethoxycarbonyl. The alkoxycarbonylamino group preferably has 2 to 10 carbon atoms. Examples of the alkoxycarbonylamino group include methoxycarbonylamino and ethoxycarbonylamino.

The number of carbon atoms in the alkylthio group is 1 to 1.
It is preferably 2. Examples of the alkylthio group include methylthio, ethylthio and octylthio.
The alkylsulfonyl group preferably has 1 to 8 carbon atoms. Examples of alkylsulfonyl groups include methanesulfonyl and ethanesulfonyl. The number of carbon atoms in the aliphatic amide group is preferably 1-10. Examples of the aliphatic amide group include acetamide. The aliphatic sulfonamide group preferably has 1 to 8 carbon atoms. Examples of the aliphatic sulfonamide group include methanesulfonamide, butanesulfonamide and n-octanesulfonamide. The aliphatic substituted amino group preferably has 1 to 10 carbon atoms. Examples of the aliphatic substituted amino group include dimethylamino, diethylamino and 2-carboxyethylamino. The number of carbon atoms of the aliphatic-substituted carbamoyl group is preferably 2-10. Examples of the aliphatic substituted carbamoyl group include methylcarbamoyl and diethylcarbamoyl. The number of carbon atoms of the aliphatic-substituted sulfamoyl group is preferably 1-8. Examples of the aliphatic substituted sulfamoyl group include methylsulfamoyl and diethylsulfamoyl. The aliphatic substituted ureido group preferably has 2 to 10 carbon atoms. Examples of the aliphatic substituted ureido group include methylureido. Examples of the non-aromatic heterocyclic group include piperidino and morpholino.

The retardation increasing agent has a molecular weight of 30.
It is preferably 0 to 800. The retardation increasing agent is also described in JP-A Nos. 2000-111914 and 2000-275434, and the compounds described in the respective publications can be used.

(Protective Film) The polarizing film of the present invention is preferably used as a polarizing plate by attaching a protective film on both sides or one side. The type of the protective film is not particularly limited, and cellulose acylates such as cellulose acetate and cellulose acetate butyrate, polycarbonate, polyolefin, polystyrene, polyester and the like can be used. Physical properties such as transparency, appropriate moisture permeability, low birefringence, and appropriate rigidity are required for the protective film of the polarizing plate, and synthetically, cellulose acylates are preferable, and cellulose acetate is particularly preferable.

The protective film is usually supplied in a roll form,
It is preferable that the long circularly polarizing plate is continuously laminated so that the longitudinal directions thereof coincide with each other. Here, the orientation axis (slow axis) of the protective film may be in any direction,
The orientation axis of the protective film is preferably parallel to the longitudinal direction for ease of operation.

The angle between the slow axis (alignment axis) of the protective film and the absorption axis (stretching axis) of the polarizing film is not particularly limited, and can be set appropriately according to the purpose of the circularly polarizing plate. Since the absorption axis of the long circularly polarizing plate of the present invention is not parallel to the longitudinal direction, a protective film having an alignment axis parallel to the longitudinal direction is continuously adhered to the long circularly polarizing plate of the present invention. A polarizing plate in which the absorption axis of the polarizing film and the alignment axis of the protective film are not parallel can be obtained. The angle between the slow axis of the protective film and the absorption axis of the polarizing film is 1
At 0 ° or more and less than 90 °, the dimensional stability effect is effectively exhibited. Further, it is preferably 20 ° or more and 80 ° or less.

The physical properties of the protective film can be set to any values depending on the application, but typical preferred values for use in ordinary transmissive LCDs are shown below. The film thickness is preferably 5 to 500 μm from the viewpoint of handleability and durability, and 20 to 200 μm.
m is more preferable, and 20 to 100 μm is particularly preferable.
Retardation value is 0 to 15 at 632.8 nm
0 nm is preferable, 0 to 20 nm is more preferable, and 0 to
5 nm is particularly preferred. It is preferable that the slow axis of the protective film is made substantially parallel or orthogonal to the absorption axis of the polarizing film from the viewpoint of avoiding elliptical polarization of linearly polarized light. However, when the protective film has a function of changing the polarization property such as a phase difference plate, the invention is not limited to this, and the absorption axis of the polarizing plate and the slow axis of the protective film can take an arbitrary angle.

The visible light transmittance is preferably 60% or more,
90% or more is particularly preferable. The dimensional reduction after treatment at 90 ° C. for 120 hours is preferably 0.3 to 0.01%, particularly preferably 0.15 to 0.01%.
The tensile strength value by the tensile test of the film is 50 to 10
00 MPa is preferable, and 100 to 300 MPa is particularly preferable. The water vapor transmission rate of the film is 100 to 800 g / m ^2.
・ Day is preferable, 300 to 600 g / m ² · day
Is particularly preferable. Of course, the application of the present invention is not limited to the above values.

Details of cellulose acylate preferable as a protective film are shown below. A preferred cellulose acylate is one in which the degree of substitution of cellulose with hydroxyl groups satisfies all of the following formulas (I) to (IV).

[0050] (I) 2.6 ≦ A + B ≦ 3.0 (II) 2.0 ≦ A ≦ 3.0 (III) 0 ≦ B ≦ 0.8 (IV) 1.9 <A-B

Here, A and B in the formula represent a substituent of an acyl group substituted by a hydroxyl group of cellulose, A is a substitution degree of an acetyl group, and B is a substitution of an acyl group having 3 to 5 carbon atoms. It is degree. Cellulose has 3 in 1 glucose unit
There is one hydroxyl group, and the above number represents the degree of substitution for the hydroxyl group 3.0, and the maximum degree of substitution is 3.0. Cellulose triacetate generally has a degree of substitution of A of 2.6 or more and 3.0 or less (in this case, the maximum number of unsubstituted hydroxyl groups is 0.4), and B = 0 is cellulose triacetate. Cellulose acylate used as a protective film for a polarizing plate includes cellulose triacetate in which all acyl groups are acetyl groups, and 2.0 in acetyl groups.
As described above, the acyl group having 3 to 5 carbon atoms is 0.8 or less,
It is preferable that the non-substituted hydroxyl group is 0.4 or less. In the case of an acyl group having 3 to 5 carbon atoms, 0.3 or less is particularly preferable from the viewpoint of physical properties. The degree of substitution is obtained by measuring the degree of bonding of acetic acid and fatty acids having 3 to 5 carbon atoms, which substitute for the hydroxyl groups of cellulose. The measuring method can be carried out according to ASTM D-817-91.

Other acyl groups having 3 to 5 carbon atoms other than acetyl group are propionyl group (C ₂ H ₅ CO-), butyryl group (C ₃ H ₇ CO-) (n-, iso-), valeryl group ( C
₄ H ₉ CO-) (n-, iso-, sec-, tert
-), Among these, n-substituted ones are preferable in terms of mechanical strength when formed into a film, ease of dissolution, etc., and particularly n-
A propionyl group is preferred. Further, if the substitution degree of the acetyl group is low, mechanical strength and resistance to moist heat are deteriorated. When the degree of substitution of the acyl group having 3 to 5 carbon atoms is high, the solubility in an organic solvent is improved, but when the degree of substitution is within the above range, good physical properties are exhibited.

The degree of polymerization (viscosity average) of the cellulose acylate is preferably 200 to 700, particularly 250 to 550.
Are preferred. The viscosity average degree of polymerization can be measured with an Ostwald viscometer, and is calculated from the measured intrinsic viscosity [η] of cellulose acylate by the following formula. DP = [η] / Km (where DP is the viscosity average degree of polymerization,
Km is a constant 6 × 10 ^-4 )

Examples of the cellulose as the raw material for the cellulose acylate include cotton linter and wood pulp. Cellulose acylates obtained from any of the raw materials may be used, or they may be mixed and used.

(Production of Polymer Film) The above-mentioned cellulose acylate is usually produced by a solvent casting method. The solvent cast method is a concentrated solution prepared by dissolving cellulose acylate and various additives in a solvent (hereinafter,
(Referred to as a dope), which is cast on an endless support such as a drum or band, and the solvent is evaporated to form a film. The dope has a solid content of 10
It is preferable to adjust the concentration so as to be ˜40% by weight. The surface of the drum or band is preferably mirror-finished. For the casting and drying method in the solvent casting method, see US Pat. No. 2,336,310.
No. 2367603, No. 2492078, No. 24
92977, 2492978, 2607704.
Nos. 2739069, 2739070, British Patents 640731 and 736892, Japanese Patent Publications Nos. 45-4554, 49-5614, and JP-A-60.
-176834, 60-203430, 62-
It is described in each publication of No. 115035.

A method of casting two or more layers of dope is also preferably used. In the case of casting a plurality of dopes, a film may be produced by casting and laminating a solution containing a dope from a plurality of casting ports provided at intervals in the traveling direction of a support, for example, Kaisho 61-158414
No. 1,122,419 and No. 11-1982.
The method described in No. 85, etc. can be applied. Further, the cellulose acylate solution may be cast from two casting ports to form a film.
0-27562, JP-A-61-94724, JP-A-61-942245, JP-A-61-104813,
JP-A-61-158413, JP-A-6-134933
No., can be carried out. In addition, JP-A-56-1
A casting method described in No. 62617, in which a high-viscosity dope flow is wrapped with a low-viscosity dope and the high- and low-viscosity dopes are simultaneously extruded, is also preferably used.

Examples of organic solvents that dissolve cellulose acylate include hydrocarbons (eg, benzene, toluene), halogenated hydrocarbons (eg, methylene chloride, chlorobenzene), alcohols (eg, methanol, ethanol, diethylene glycol), Examples include ketones (eg, acetone), esters (eg, ethyl acetate, propyl acetate) and ethers (eg, tetrahydrofuran, methyl cellosolve) and the like. Halogenated hydrocarbons having 1 to 7 carbon atoms are preferably used, and methylene chloride is most preferably used. From the viewpoint of physical properties such as solubility of cellulose acylate, peelability from a support, mechanical strength of a film, optical properties, etc., in addition to methylene chloride, it has 1 carbon atom.
It is preferable to mix one to several kinds of alcohols (5) to (5). The content of alcohol is 2 to the whole solvent.
25 mass% is preferable and 5 to 20 mass% is more preferable. Specific examples of the alcohol include methanol, ethanol, n-propanol, isopropanol, n-butanol, etc., but methanol, ethanol, n
-Butanol or mixtures thereof are preferably used.

In addition to cellulose acylate, components that become solid after drying include plasticizers, ultraviolet absorbers, inorganic fine particles, heat stabilizers such as salts of alkaline earth metals such as calcium and magnesium, and electrification. It may optionally contain an inhibitor, a flame retardant, a lubricant, an oil agent, a release accelerator from the support, a hydrolysis inhibitor of cellulose acylate, and the like.

As the plasticizer preferably added, phosphoric acid ester or carboxylic acid ester is used. Examples of phosphate esters include triphenyl phosphate (TPP) and tricresyl phosphate (TC).
P), cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenyl biphenyl phosphate, trioctyl phosphate, tributyl phosphate and the like. Typical carboxylic acid esters are phthalic acid esters and citric acid esters. Examples of phthalates include dimethyl phthalate (DMP), diethyl phthalate (DEP), dibutyl phthalate (DBP), dioctyl phthalate (DO).
P), diphenyl phthalate (DPP) and diethylhexyl phthalate (DEHP). Examples of citrate esters include O-acetyl triethyl citrate (OACTE) and O-acetyl tributyl citrate (OACTB), acetyl triethyl citrate, acetyl tributyl citrate. Examples of other carboxylic acid esters include trimellitic acid esters such as butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and trimethyl trimellitate. Examples of glycolic acid esters include triacetin, tributyrin, butylphthalylbutyl glycolate, ethylphthalylethyl glycolate, methylphthalylethyl glycolate, butylphthalylbutyl glycolate, and the like.

Among the plasticizers exemplified above, triphenyl phosphate, biphenyl diphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, tributyl phosphate, dimethyl phthalate, diethyl phthalate, dibutyl phthalate, dioctyl phthalate, It is preferable to use diethylhexyl phthalate, triacetin, ethylphthalylethyl glycolate, trimethyl trimellitate and the like. In particular, triphenyl phosphate, biphenyl diphenyl phosphate, diethyl phthalate, ethylphthalyl ethyl glycolate and trimethyl trimellitate are preferable. These plasticizers may be used alone or in combination of two or more. The addition amount of the plasticizer is preferably 5 to 30% by mass, and particularly preferably 8 to 16% by mass or less based on the cellulose acylate. These compounds may be added together with the cellulose acylate or the solvent when preparing the cellulose acylate solution, or may be added during or after the solution preparation.

As the ultraviolet absorber, any kind can be selected according to the purpose, and a salicylate-based, benzophenone-based, benzotriazole-based, benzoate-based, cyanoacrylate-based, nickel complex salt-based absorbent or the like is used. However, benzophenone type, benzotriazole type, and salicylic acid ester type are preferable. Examples of the benzophenone-based ultraviolet absorber include 2,4-dihydroxybenzophenone, 2-hydroxy-4-acetoxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4-methoxybenzophenone, 2, 2'-di-hydroxy-4,4 '
-Methoxybenzophenone, 2-hydroxy-4-n-
Octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone, 2-hydroxy-4- (2
-Hydroxy-3-methacryloxy) propoxybenzophenone and the like can be mentioned. As a benzotriazole-based ultraviolet absorber, 2 (2′-hydroxy-3 ′)
-Tert-butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2 (2'-hydroxy-5 '
-Tert-butylphenyl) benzotriazole, 2
(2'-Hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole, 2 (2'-hydroxy-3', 5'-di-tert-butylphenyl) -5
-Chlorobenzotriazole, 2 (2'-hydroxy-
5'-tert-octylphenyl) benzotriazole and the like can be mentioned. Examples of salicylic acid ester-based compounds include phenyl salicylate, p-octylphenyl salicylate and p-tert-butylphenyl salicylate. Among these exemplified ultraviolet absorbers, 2-hydroxy-4-methoxybenzophenone, 2,2′-di-hydroxy-4,4′-methoxybenzophenone, 2 (2′-hydroxy-3′-) are particularly preferable.
tert-Butyl-5'-methylphenyl) -5-chlorobenzotriazole, 2 (2'-hydroxy-5'-
tert-butylphenyl) benzotriazole, 2
(2'-Hydroxy-3 ', 5'-di-tert-amylphenyl) benzotriazole, 2 (2'-hydroxy-3', 5'-di-tert-butylphenyl) -5
-Chlorobenzotriazole is particularly preferred.

It is particularly preferable to use a plurality of absorbents having different absorption wavelengths in combination because a high blocking effect can be obtained in a wide wavelength range. The amount of the ultraviolet absorber is preferably 0.01 to 5 mass% with respect to the cellulose acylate,
1 to 3 mass% is particularly preferable. The ultraviolet absorber may be added at the same time when the cellulose acylate is dissolved, or may be added to the dope after the dissolution. Particularly, it is preferable to use a static mixer or the like and add the ultraviolet absorbent solution to the dope immediately before casting.

The inorganic fine particles added to the cellulose acylate include silica, kaolin, talc, diatomaceous earth,
Quartz, calcium carbonate, barium sulfate, titanium oxide, alumina, etc. can be arbitrarily used according to the purpose.
Before adding these fine particles to the dope, use a high speed mixer,
It is preferable to perform dispersion in the binder solution by any means such as a ball mill, an attritor, an ultrasonic disperser or the like. Cellulose acylate is preferable as the binder. It is also preferable to carry out dispersion with other additives such as an ultraviolet absorber. Although the dispersion solvent is arbitrary, it is preferable that the composition be similar to that of the dope solvent. The number average particle diameter of dispersed particles is 0.0
1 to 100 μm is preferable, and 0.1 to 10 μm is particularly preferable. The above dispersion may be added to the cellulose acylate dissolution step at the same time or may be added to the dope at any step, but it is preferable to add it just before casting using a static mixer or the like like an ultraviolet absorber.

As the release accelerator from the support, a surfactant is effective, and phosphoric acid type, sulfonic acid type, carboxylic acid type, nonionic type, cationic type and the like are not particularly limited.
These are described, for example, in JP-A-61-243837.

When the above-mentioned cellulose acylate film is used as a protective film, in order to improve the adhesion with the PVA type resin, the film surface is made hydrophilic by means such as saponification, corona treatment, flame treatment, glow discharge treatment and the like. It is preferable to add. Further, the hydrophilic resin may be dispersed in a solvent having an affinity for cellulose acylate and applied in a thin layer. Among the above means, saponification treatment is particularly preferable because the flatness and physical properties of the film are not impaired. The saponification treatment is performed by immersing the film in an aqueous alkaline solution such as caustic soda. After the treatment, in order to remove excess alkali, it is preferable to neutralize with a low-concentration acid and sufficiently wash with water.

The alkali saponification treatment preferably used as the surface treatment of the cellulose acylate film will be specifically described. It is preferable that the surface of the cellulose acylate film is immersed in an alkaline solution, neutralized with an acidic solution, washed with water and dried. Examples of the alkaline solution include potassium hydroxide solution and sodium hydroxide solution, and the normal concentration of hydroxide ion is 0.1 N to
It is preferably 3.0 N, and more preferably 0.5 N to 2.0 N. The temperature of the alkaline solution is preferably in the range of room temperature to 90 ° C, preferably 40 ° C to 70 ° C.
C is even more preferred. Next, it is generally washed with water, and after passing an acidic aqueous solution, it is washed with water to obtain a surface-treated cellulose acylate film. At this time, the acid is hydrochloric acid, nitric acid, sulfuric acid, acetic acid, formic acid, chloroacetic acid, oxalic acid or the like, and the concentration thereof is preferably 0.01N to 3.0N, and 0.05N to 2.0N. Is more preferable. When the cellulose acylate film is used as a transparent protective film of a polarizing plate, it is particularly preferable to carry out acid treatment, alkali treatment, that is, saponification treatment of cellulose acylate, from the viewpoint of adhesion to the polarizing film.

The surface energy of the solid obtained by these methods is "basic and application of wetting" (Realize 198).
9.12.10), it can be determined by the contact angle method, the heat of wetting method, and the adsorption method, and the contact angle method is preferably used, and the contact angle of water is 5 to 90 ° C., and Is preferably 5 to 70 ° C.

On the surface of the protective film of the circularly polarizing plate of the present invention, there is an optical difference for compensating the viewing angle of LCD described in JP-A-4-229828, JP-A-6-75115, JP-A-8-50206 and the like. Layer, an antiglare layer or an antireflection layer for improving the visibility of the display, or a layer having a PS wave separating function by anisotropic scattering or anisotropic optical interference for improving the LCD brightness (polymer dispersed liquid crystal). Layer, cholesteric liquid crystal layer, etc.), a hard coat layer for enhancing the scratch resistance of the polarizing plate,
Arbitrary functional layers such as a gas barrier layer that suppresses diffusion of water and oxygen, a polarizing film or an adhesive, an easily adhesive layer that enhances adhesion with a pressure-sensitive adhesive, and a layer that imparts slipperiness can be provided. The functional layer may be provided on the polarizing film side or the surface opposite to the polarizing film, and can be appropriately selected depending on the purpose.

On the polarizing film of the present invention, various functional films can be directly laminated on one side or both sides as a protective film. Examples of the functional film include a retardation film such as a λ / 4 plate and a λ / 2 plate, a light diffusion film, a plastic cell provided with a conductive layer on the surface opposite to the polarizing plate, and anisotropic scattering and anisotropic optical interference. Examples thereof include a brightness enhancement film having a function and the like, a reflector, a reflector having a semi-transmissive function, and the like.

As the protective film of the polarizing plate, one or more of the above-mentioned preferred protective films can be laminated and used. The same protective film may be attached to both surfaces of the polarizing film, or protective films having different functions and physical properties may be attached to both surfaces. In addition, the above protective film is pasted only on one side,
In order to directly bond the liquid crystal cell to the opposite surface, it is possible to directly provide an adhesive layer and not bond the protective film. In this case, it is preferable to provide a peelable separator film on the outside of the adhesive.

(Surface protection film) Examples of the surface protection film include a hard coat layer, an AG layer, an AR layer and a CV layer. Each of these layers may be a single layer or may be composed of a plurality of layers, but is preferably a single layer which is simple in terms of manufacturing process. In this case, the single layer is a layer formed of the same composition, and may be formed by coating a plurality of times as long as the composition after coating and drying has the same composition. On the other hand, a plurality of layers means being formed by a plurality of compositions having different compositions. Also, a plurality of these layers may be used in combination.

The hard coat layer preferably contains a curable composition, and particularly contains a compound containing an ethylenically unsaturated group and a compound containing three or more ring-opening polymerizable groups in the same molecule. It is preferably formed from a curable composition. When the curing reaction is carried out, it is preferable that the contained components undergo a crosslinking reaction. The crosslinking reaction may be either a radical polymerization reaction or a cationic polymerization reaction, and in any case, the polymerization reaction can proceed by the action of heat and / or light. In the polymerization reaction, a small amount of a radical generator or a cation generator (or an acid generator) usually called a polymerization initiator is added, and these are decomposed by heat and / or light to generate a radical or a cation. The method of advancing the polymerization reaction is general. The radical polymerization and the cationic polymerization may be performed separately, but it is preferable to proceed at the same time. The polymerization reaction includes a method of simply heating as a method of proceeding a crosslinking reaction without adding a radical generator, but a method of irradiating with active energy rays such as radiation, gamma rays, alpha rays, electron rays and ultraviolet rays is used. It is preferably used.

Crosslinked fine particles can be added to the curable composition, if desired. When crosslinked fine particles are added,
Since the curing shrinkage amount of the hard coat layer can be reduced, the adhesion to the substrate is improved, and further, when the substrate is a plastic film, curling can be reduced. As the crosslinked fine particles, any of inorganic fine particles, organic fine particles, and organic-inorganic composite fine particles can be used without particular limitation. Examples of the inorganic fine particles include silicon dioxide particles, titanium dioxide particles, zirconium oxide particles, aluminum oxide particles and the like. Inorganic fine particles are generally hard, and by filling the hard coat layer, not only the shrinkage upon curing can be improved, but also the surface hardness can be increased. In general, the inorganic fine particles have a low affinity with the organic component such as the polymer of the present invention and the polyfunctional vinyl monomer. There is. Therefore, in order to increase the affinity between the inorganic fine particles and the organic component, the surface of the inorganic fine particles can be treated with a surface modifier containing an organic segment.

Examples of the organic fine particles include polyethylene, polypropylene, polytetrafluoroethylene, nylon, polyethylene terephthalate, polystyrene,
Examples thereof include crosslinked general-purpose resins such as poly (meth) acrylic acid esters and amides, polyvinyl chloride, acetylcellulose, nitrocellulose, and polydimethylsiloxane, and crosslinked rubber fine particles such as SBR and NBR.

The film thickness of the hard coat layer varies depending on the hardness of the substrate to be coated, and by increasing the film thickness of the hard coat layer, the hardness is high, and the effect of making cracked film peeling less prominent appears. The preferable film thickness is 1 to 200 μm, preferably 20 to 200 μm, more preferably 30 to 200 μm, and further preferably 40 to
200 μm, most preferably 50 to 200 μm.

The hardness of the surface of the hard coat layer formed from the curable composition varies depending on the kind of the base material to which the curable composition is applied, but is preferably high. The surface hardness referred to in the present invention can be represented by a pencil hardness defined in JIS K5400, and the hardness can be evaluated by directly scratching the surface of the hard coat layer with a pencil. The hardness of the surface of the hard coat layer is a pencil hardness of 3H.
-9H, preferably 4H-9H, more preferably 5H-
9H.

Further, for the purpose of improving the adhesiveness between the base material and the hard coat layer, one surface or both surfaces can be subjected to a surface treatment by an oxidation method or a textured method, if desired. Examples of the surface treatment method include chemical treatment, mechanical treatment, corona discharge treatment, glow discharge treatment, chromic acid treatment (wet),
Flame treatment, high frequency treatment, hot air treatment, ozone treatment, ultraviolet irradiation treatment, active plasma treatment, mixed acid treatment and the like can be mentioned. Furthermore, more than one undercoat layer can be provided.
As the material of the undercoat layer, vinyl chloride, vinylidene chloride,
Butadiene, (meth) acrylic acid ester, styrene,
Copolymers such as vinyl ester and latex thereof,
Examples thereof include water-soluble polymers such as polyester, polyurethane, and gelatin.

Furthermore, on the hard coat layer, an antireflection layer,
A functional layer having various functions such as an ultraviolet / infrared absorbing layer, a selective wavelength absorbing layer, an electromagnetic wave shielding layer and an antifouling layer can be provided. These functional layers can be produced by a conventionally known technique. Further, for the purpose of improving the adhesiveness between the functional layer and the hard coat layer, the hard coat layer may be subjected to a surface treatment or an adhesive layer may be provided.

<Polarizing Film> The obliquely oriented polarizing plate of the present invention can be easily obtained by the method described below.
That is, the oblique orientation is obtained by stretching the polymer film, and the devolatilization ratio of the film during stretching, the shrinkage ratio when shrinking the film, and the elastic modulus of the film before stretching are devised. Furthermore, it is also preferable to adjust the amount of foreign matter attached to the film before stretching. As a result, even if the film is obliquely stretched, the stretched film is free from wrinkles and wrinkles, and it is possible to obtain a polarizing film having a small surface roughness and excellent smoothness. In addition, since wrinkles and wrinkles do not occur and no bending occurs, it is presumed that the stretching tension applied to the film does not decrease and, therefore, no streak-like color change occurs.

The preferred stretching method for obtaining the polarizing plate of the present invention (hereinafter sometimes referred to as the stretching method of the present invention) will be described in detail below.

(Stretching Method) FIGS. 3 and 4 show an example of a method for obliquely stretching a polymer film as a schematic plan view. The stretching method of the present invention comprises a step of introducing a raw film shown in (a) in the direction of arrow (a), a width direction stretching step shown in (b), and a stretched film shown in (c) in the next step. That is, the step of sending in the (b) direction is included. Hereinafter, when referred to as "stretching step", these (a) ~
The whole process including the process (c) for performing the extending | stretching method of this invention is pointed out.

The film is continuously introduced from the direction (a) and is first held by the holding means on the left side when viewed from the upstream side at point B1. At this point, one film edge is not held yet, and no tension is generated in the width direction. That is, B
One point does not correspond to the substantial holding start point (hereinafter, referred to as “substantial holding start point”) of the present invention. In the present invention, the substantial retention start point is defined as the point where both ends of the film are retained for the first time. The actual holding start point is the holding start point A on the downstream side.
1 and a straight line drawn from A1 substantially perpendicularly to the center line 11 (FIG. 3) or 21 (FIG. 4) of the introduction side film is the locus 13 (FIG. 3) or 23 (FIG. 4) of the holding means on the opposite side. It is shown by two points of intersection C1. Starting from this point, when the holding means at both ends is conveyed at a substantially constant speed, A1 moves to A2, A3 ... An every unit time, and C1 similarly moves to C2.
Move to C3 ... Cn. That is, the straight line connecting the points An and Cn through which the holding means serving as the reference passes at the same point is the stretching direction at that time.

In the method of the present invention, as shown in FIGS.
Since n gradually lags behind Cn, the stretching direction is gradually inclined from the direction perpendicular to the transport direction. The substantial holding release point of the present invention (hereinafter referred to as "substantial holding release point") is a Cx point that is separated from the holding means at a more upstream side, and a center line 12 of the film sent from Cx to the next step (FIG. 3). Or 22
A straight line drawn substantially perpendicular to (FIG. 4) is defined by two points Ay intersecting the trajectory 14 (FIG. 3) or 24 (FIG. 4) of the holding means on the opposite side. The final angle in the stretching direction of the film is determined by the stroke difference Ay-Ax (that is, | L1-L2) of the left and right holding means at the end point (substantially holding release point) of the substantial stretching step.
|) And the distance W between the substantial holding release points (distance between Cx and Ay)
And the ratio. Therefore, the inclination angle θ formed by the stretching direction with respect to the conveying direction to the next step is an angle that satisfies the following formula.

Tan θ = W / (Ay-Ax), that is, tan θ = W / | L1-L2 |

The upper film edge in FIGS. 3 and 4 is Ay.
After the point, it is held up to 18 (Fig. 3) or 28 (Fig. 4), but since the other end is not held, new widthwise stretching does not occur, and 18 and 28 are the substantial holding release points of the present invention. is not.

As described above, in the present invention, the substantial holding start points at both ends of the film are not the simple biting points into the left and right holding means. The two substantial holding start points of the present invention are, if the above definition is described more strictly, a film in which a straight line connecting either the left or right holding point and the other holding point is introduced in the step of holding the film. Is substantially orthogonal to the centerline of the, and these two holding points are defined as the most upstream positions. Similarly,
In the present invention, the two substantial holding release points, a straight line connecting either the left or right holding point and the other holding point is a point substantially orthogonal to the center line of the film sent to the next step,
Moreover, these two holding points are defined as being located at the most downstream. Here, “substantially orthogonal” means that the straight line connecting the center line of the film and the left and right substantial holding start points or substantial holding release points is 90 ± 0.5 °.

When an attempt is made to make a difference in the left and right strokes by using a tenter type stretching machine, a large deviation often occurs between the biting point into the holding means and the actual holding start point due to mechanical restrictions such as rail length. A large deviation may occur between the detachment point from the holding means and the substantial holding release point, but if the process between the substantial holding start point and the substantial holding release point defined above satisfies the relationship of formula (1), The object of the invention is achieved.

In the above, the inclination angle of the orientation axis in the obtained stretched film is controlled and adjusted by the ratio of the exit width W in the step (c) and the stroke difference | L1-L2 | between the two left and right holding means. can do. For polarizing plates and retardation films, films oriented at 45 ° with respect to the longitudinal direction are often required. In this case, in order to obtain an orientation angle close to 45 °, it is preferable to satisfy the following formula (2), and the following formula (3) is more preferable: 0.9W <| L1-L2 | <1.1W ) Is preferably satisfied. Formula (3) 0.97W <| L1-L2 | <1.03W

As long as the formula (1) is satisfied, the concrete structure of the stretching step can be arbitrarily designed in consideration of equipment cost and productivity as illustrated in FIGS.

The film introduction direction (a) in the stretching step,
The angle formed by the film transport direction (b) to the next step can be any value, but from the viewpoint of minimizing the total installation area of equipment including the steps before and after stretching, this angle should be smaller. It is preferably within 3 °, more preferably within 0.5 °. For example, in the structure illustrated in FIGS. 3 and 6,
This value can be achieved. In such a method in which the film advancing direction does not substantially change, it is difficult to obtain an orientation angle of 45 ° with respect to the longitudinal direction, which is preferable as a polarizing plate or a retardation film, only by increasing the width of the holding means. .
Therefore, as shown in FIG. 3, | L1-L2 | can be increased by providing a process of once stretching and then contracting. The stretch ratio is preferably 1.1 to 10.0 times, more preferably 2 to 10 times, and the shrinkage ratio thereafter is preferably 10% or more. Further, as shown in FIG. 6, it is also preferable to repeat stretching-shrinkage a plurality of times because | L1-L2 | can be increased.

From the viewpoint of minimizing the equipment cost of the stretching process, the smaller the number of bendings and the bending angle of the locus of the holding means, the better. From this point of view, as shown in FIGS. 4, 5 and 7, the angle between the film advancing direction at the exit of the step of holding both ends of the film and the substantial stretching direction of the film is inclined by 20 to 70 °. It is preferable to bend the film in a state where both ends of the film are held in the traveling direction.

In the present invention, the apparatus for stretching the film by applying tension while holding both ends is so-called FIG.
A tenter device such as that of FIG. 7 is preferred. In addition to the conventional two-dimensional tenter, it is also possible to use a stretching step in which the gripping means at both ends are spirally provided with a path difference as shown in FIG.

In the case of a tenter type stretching machine, there are many structures in which a chain to which a clip is fixed advances along a rail.
If the left-right unequal stretching method is adopted as in the present invention, as a result, as shown in FIGS. 3 and 4, the rail ends are displaced at the process inlet and outlet, and the left and right sides are simultaneously bitten and the rails do not disengage. is there. In this case, the substantial process lengths L1 and L2 are not the simple bite-release distances as described above, but the strokes of the portions where the holding means holds both ends of the film, as already described. Be long.

If there is a difference in the traveling speed of the film at the exit of the stretching process, a wrinkle or a deviation occurs at the exit of the stretching process. Therefore, the difference in transport speed between the left and right film gripping means is substantially the same. Desired. The speed difference is preferably 1% or less, more preferably less than 0.5%, most preferably less than 0.05%. The speed described here is the length of the trajectory of the left and right holding means per minute. In a typical tenter stretching machine, etc., there are speed irregularities that occur on the order of seconds or less depending on the cycle of the sprocket teeth that drive the chain, the frequency of the drive motor, etc. It does not correspond to the speed difference described in the invention.

(Shrinkage) The shrinkage of the stretched polymer film is
It may be carried out at any step during and after the stretching. The shrinkage may be such that wrinkles of the polymer film that occur when oriented in an oblique direction are eliminated, and means for shrinking the film include a method of removing volatile matter by applying temperature, but the film is Any means may be used as long as it contracts. The shrinkage ratio of the film is preferably 1 / sin using the orientation angle θ with respect to the longitudinal direction.
By shrinking by θ times or more, it is preferable that the value shrinks by 10% or more.

(Volatile Content) Further, as the difference between the left and right strokes occurs, wrinkles and deviations occur in the film. In order to solve this problem, the present invention is characterized by maintaining the supportability of the polymer film, allowing the polymer film to have a volatile content of 5% or more, stretching, and then contracting to reduce the volatile content. The volatile content in the present invention represents the volume of the volatile component contained per unit volume of the film, and is the value obtained by dividing the volatile component volume by the film volume. Examples of the method of incorporating a volatile component include casting a film to contain a solvent / water, dipping / coating / spraying in a solvent / water or the like before stretching, or coating a solvent / water during stretching. Since a hydrophilic polymer film such as polyvinyl alcohol contains water in a high-temperature and high-humidity atmosphere, it can be made to contain a volatile component by stretching after conditioning in a high-humidity atmosphere or under high-humidity conditions. . Other than these methods, any means may be used as long as the volatile content of the polymer film can be made 5% or more.

The preferred volatile content depends on the type of polymer film. The maximum volatile content is possible as long as the support of the polymer film is maintained. For polyvinyl alcohol, the volatile content is preferably 10% to 100%.
Cellulose acylate is preferably 10% to 200%.

(Elastic Modulus) As for the physical properties of the polymer film before stretching, if the elastic modulus is too low, the shrinkage ratio during and after stretching becomes low, and wrinkles are hard to disappear. On the other hand, if it is too high, the tension applied during stretching becomes large, and it becomes necessary to increase the strength of the portions holding both ends of the film, which increases the load on the machine. Therefore, the elastic modulus of the polymer film before stretching of the present invention is 0.1 Mpa or more and 500 Mpa or less, preferably 0.1 Mpa or more and 500 Mpa or less when expressed by Young's modulus.

(Distance from Wrinkle Occurrence to Disappearance) The wrinkle of the polymer film generated when the film is oriented in an oblique direction has only to disappear until the substantial holding release point in the present invention. However, if it takes time from the occurrence of wrinkles to the disappearance of the wrinkles, variations in the stretching direction may occur. Therefore, it is preferable that the wrinkles disappear at a transition distance as short as possible from the point where the wrinkles occur. For this purpose, there is a method of increasing the volatilization rate of the volatile content.

(Foreign matter) In the present invention, if foreign matter adheres to the polymer film before stretching, the surface becomes rough, so it is preferable to remove the foreign matter. The presence of foreign matter causes color unevenness and optical unevenness, especially when a polarizing plate is manufactured. It is also important that no foreign matter adheres before the protective film is attached, and it is preferable to manufacture in an environment where floating dust is minimized. The amount of foreign matter in the present invention is a value obtained by dividing the weight of foreign matter adhering to the film surface by the surface area, and represents the number of grams per square meter. The amount of foreign matter is preferably 1 g / m ² or less, more preferably 0.5 g / m ² or less, and the smaller the amount, the more preferable.

The method of removing foreign matter is not particularly limited,
Without adversely affecting the polymer film before stretching,
Any method may be used as long as the foreign matter can be removed. For example, a method of scraping off a foreign object by blowing a water stream, a method of scraping off a foreign object by jetting a gas, a cloth,
A method of scraping off a foreign substance by using a blade such as rubber may be used.

(Drying) Any drying condition may be used as long as the generated wrinkles disappear. However, it is preferable to adjust the drying point so that the drying point comes as short as possible after the desired orientation angle is obtained. The dry point means a place where the surface film temperature of the film becomes the same as the ambient atmospheric temperature. From this, it is preferable that the drying rate is as high as possible.

(Drying temperature) The drying conditions may be any as long as the generated wrinkles disappear, but it depends on the film to be stretched. When a polarizing plate is prepared using a polyvinyl alcohol film according to the present invention, the temperature is preferably 20 ° C or higher and 100 ° C or lower, more preferably 40 ° C or higher and 90 ° C or lower.

(Swelling ratio) In the present invention, when the polymer film is polyvinyl alcohol and a hardening agent is used, in order to keep the stretched state in an oblique direction without being relaxed,
It is preferable that the swelling ratio in water is different before and after stretching.
Specifically, it is preferable that the swelling rate before stretching is high and the swelling rate after stretching / drying is low. More preferably, the swelling rate in water before stretching is more than 3%, and the swelling rate after drying is preferably 3% or less.

(Definition of Refraction Part) In the present invention, a rail that regulates the locus of the holding means is often required to have a large bending rate. Interference between film gripping means due to sudden bending,
Alternatively, for the purpose of avoiding local concentration of stress, it is desirable that the trajectory of the gripping means draws an arc at the bent portion.

(Stretching Speed) In the present invention, the speed at which the film is stretched is 1.1 in terms of the stretching ratio per unit time.
Double / minute or more, preferably double / minute or more, and the earlier one is preferable. In addition, the traveling speed in the longitudinal direction is 0.1 m / min or more, preferably 1 m / min or more, and the higher speed is preferable from the viewpoint of productivity. In either case, the upper limit depends on the film to be stretched and the stretching machine.

(Tension in the longitudinal direction) In the present invention, when the both ends of the film are held by the holding means, it is preferable that the film is stretched so as to be easily held. Specifically, a method of applying tension in the longitudinal direction to stretch the film may be used. Although the tension varies depending on the film state before stretching, it is preferable that the tension does not loosen.

(Temperature at Stretching) In the present invention, the environmental temperature at the time of stretching the film may be at least the freezing point of the volatile components contained in the film. When the film is polyvinyl alcohol, the temperature is preferably 25 ° C or higher. Also,
When stretching polyvinyl alcohol soaked with iodine / boric acid for producing a polarizing film, the temperature is 25 ° C or higher and 90 ° C or higher.
C. or less is preferable.

(Humidity at Stretching) When a film having a volatile component of water, such as polyvinyl alcohol or cellulose acylate, is stretched, it may be stretched in a humidity controlled atmosphere. In the case of polyvinyl alcohol, 50% or more is preferable, 80% or more is more preferable, and 90 is more preferable.
% Or more.

(Polymer Film for Polarizing Film) The polymer film to be stretched in the present invention is not particularly limited, and a film made of a suitable thermoplastic polymer can be used. Examples of polymers include PVA, polycarbonate, cellulose acylate, polysulfone, and the like.

Although the thickness of the film before stretching is not particularly limited, it is preferably 1 μm to 1 mm, particularly preferably 20 to 200 μm, from the viewpoint of stability of film holding and homogeneity of stretching.

The polymer for the film for the polarizing film is P
VA is preferably used. PVA is generally a saponified product of polyvinyl acetate, but may contain a component copolymerizable with vinyl acetate, such as unsaturated carboxylic acid, unsaturated sulfonic acid, olefins, vinyl ethers. . In addition, modified P containing an acetoacetyl group, a sulfonic acid group, a carboxyl group, an oxyalkylene group, etc.
VA can also be used.

Although the degree of saponification of PVA is not particularly limited,
From the viewpoint of solubility and the like, 80 to 100 mol% is preferable,
90 to 100 mol% is particularly preferable. Although the degree of polymerization of PVA is not particularly limited, it is preferably 1000 to 10000, and particularly preferably 1500 to 5000.

(Dyeing prescription / method) A polarizing film is obtained by dyeing PVA, and the dyeing step is carried out by gas phase or liquid phase adsorption. As an example of the case of using the liquid phase, when iodine is used, the PVA film is immersed in an aqueous solution of iodine-potassium iodide. Iodine is 0.1-20g /
1 and potassium iodide are preferably 1 to 200 g / l, and the weight ratio of iodine to potassium iodide is preferably 1 to 200. The dyeing time is preferably 10 to 5000 seconds, and the liquid temperature is preferably 5 to 60 ° C. As a dyeing method, not only dipping but also any means such as application or spraying of iodine or dye solution can be used. The dyeing step may be performed before or after the stretching step of the present invention, but it is particularly preferable to perform dyeing in a liquid phase before the stretching step because the film is appropriately swollen and the stretching is facilitated.

(Hardener (crosslinking agent) / metal salt addition) PVA
In the process of producing a polarizing film by stretching, it is preferable to use an additive for crosslinking PVA. Especially when the oblique stretching method of the present invention is used, if the PVA is not sufficiently hardened at the exit of the stretching step, the orientation direction of the PVA may shift due to the tension of the step. It is preferable that the cross-linking agent is contained by dipping or coating the solution with the cross-linking agent. The means for applying the cross-linking agent to the PVA film is not particularly limited, and any method such as immersion of the film in a liquid, coating or spraying can be used, but the immersion method and the coating method are particularly preferable. As a coating means, any known means such as a roll coater, a die coater, a bar coater, a slide coater, and a curtain coater can be used. A method in which a cloth, cotton, or a porous material impregnated with the solution is brought into contact with the film is also preferable. As a crosslinking agent, US Reissued Patent No. 232897
Although the compounds described in No. 1 can be used, boric acid and borax are preferably used practically. Further, metal salts such as zinc, cobalt, zirconium, iron, nickel and manganese can also be used together. A washing / water washing step may be provided after the addition of the hardener.

The cross-linking agent may be applied before biting into the stretching machine or after it is bitten in, and in the example of FIG. 3 and FIG. ) It may be performed in any step up to the end of the step.

(Polarizer) It is also preferable to dye with a dichroic dye in addition to iodine. Specific examples of dichroic dyes include dye compounds such as azo dyes, stilbene dyes, pyrazolone dyes, triphenylmethane dyes, quinoline dyes, oxazine dyes, thiazine dyes, and anthraquinone dyes. I can give you. Water-soluble compounds are preferable, but not limited thereto. Further, it is preferable that hydrophilic substituents such as sulfonic acid group, amino group and hydroxyl group are introduced into these dichroic molecules. Specific examples of the dichroic molecule include, for example, C.I. Eye. direct. Yellow 12, Sea. Eye. direct. Orange 39, C.I. Eye. direct. Orange 72, C.I. Eye. direct. Red 39, sea. Eye. direct. Red 79, sea. Eye. direct. Red 81, sea. Eye. direct. Red 83, sea. Eye. direct. Red 89, sea. Eye. direct.
Violet 48, C.I. Eye. direct. Blue 67, Sea. Eye. direct. Blue 90, Sea.
Eye. direct. Green 59, C. Eye. Acid. Red 37 and the like, and further, JP-A-62-1
70802, JP-A-1-161202 and JP-A-1-
172906, JP-A-1-172907, JP-A-1
Examples thereof include dyes described in JP-A Nos. 183602, 1-248105, 1-265205, and 7-261024. These dichroic molecules are used as free acids, or alkali metal salts, ammonium salts, and salts of amines. These dichroic molecules have 2
By mixing at least one kind, it is possible to produce a polarizer having various hues. A compound (dye) that exhibits a black color when the polarization axes are orthogonalized as a polarizing element or a polarizing plate.
Those in which various dichroic molecules are mixed so as to exhibit a black color or black are preferable because they have excellent single-plate transmittance and polarization rate.

The stretching method of the present invention is also preferably used for the production of a so-called polyvinylene-based polarizing film in which a polyene structure is formed by dehydrating and dechlorinating PVA and polyvinyl chloride, and polarized light is obtained by a conjugated double bond. You can

<Adhesive> The adhesive between the polarizing film and the protective film is not particularly limited, but a PVA-based resin (acetoacetyl group,
(Including modified PVA having a sulfonic acid group, a carboxyl group, an oxyalkylene group, etc.), an aqueous solution of a boron compound, or the like, among which a PVA-based resin is preferable. A boron compound, an aqueous potassium iodide solution or the like may be added to the PVA-based resin and used. The thickness of the adhesive layer is 0.01 to 10 μm after drying.
Is preferable, and 0.05 to 5 μm is particularly preferable.

<Consistent Step> In the present invention, there is a drying step in which the film is stretched and then contracted to reduce the volatile content. It is preferable to have
As a concrete sticking method, during the drying step, the protective film is stuck to the film with an adhesive while holding both ends, and then both ends are eared, or after drying, the film is released from both end holding parts. Alternatively, there is a method of cutting off both ends of the film and then attaching a protective film. As a method of cutting the edges, a general technique such as a method of cutting with a cutter such as a blade or a method of using a laser can be used. After the bonding, it is preferable to heat the adhesive for drying and improving the polarization performance. The heating conditions vary depending on the adhesive, but in the case of an aqueous system, it is preferably 30 ° C or higher, more preferably 4 ° C.
0 ° C to 100 ° C, more preferably 50 ° C to 8
It is 0 ° C or lower. It is more preferable in terms of performance and production efficiency that these steps are manufactured on a consistent line.

<Punching> FIG. 2 shows an example of punching the polarizing plate of the present invention. In the conventional polarizing plate, the absorption axis 71 of the polarized light, that is, the stretching axis coincides with the longitudinal direction 72.
In the polarizing plate of the present invention, as shown in FIG. 2, the absorption axis 81 of polarized light, that is, the stretching axis is inclined by 45 ° with respect to the longitudinal direction 82. Since the angle between the absorption axis of the plate and the vertical or horizontal direction of the liquid crystal cell itself is the same, diagonal punching is not necessary in the punching process. Moreover, as can be seen from FIG. 2, since the polarizing plate of the present invention has a straight cut along the longitudinal direction, it can be manufactured by slitting along the longitudinal direction without punching, so that the productivity is remarkably excellent. ing.

[0122] The circular polarizer of the <adhesive layer> The present invention an adhesive layer for bonding with another liquid crystal display device member, provided on at least one outer side of the polarizing film or an optical film. It is preferable to provide a release film on the surface of the pressure-sensitive adhesive layer. The pressure-sensitive adhesive layer not only is optically transparent, but also exhibits appropriate viscoelasticity and pressure-sensitive adhesive properties. Examples of the pressure-sensitive adhesive layer in the present invention include adhesives or pressure-sensitive adhesives such as acrylic copolymers, epoxy resins, polyurethanes, silicone polymers, polyethers, butyral resins, polyamide resins, polyvinyl alcohol resins, synthetic rubbers, etc. Using a polymer such as an agent, a film can be formed and cured by a drying method, a chemical curing method, a heat curing method, a heat melting method, a light curing method, or the like. Among them, the acrylic copolymer is most preferably used because it is most easy to control the adhesive property and is excellent in transparency, weather resistance and durability.

The pressure-sensitive adhesive layer of the present invention may be subjected to a crosslinking treatment. In that case, the cross-linking treatment with the inter-molecular cross-linking agent can be performed by a method of blending the inter-molecular cross-linking agent in the liquid of the pressure-sensitive adhesive. As the intermolecular cross-linking agent, an appropriate one can be used depending on the type of functional group in the pressure-sensitive adhesive polymer involved in inter-molecular cross-linking, and is not particularly limited, and any known one can be used.

Further, in the present invention, it is preferable that the relaxation elastic modulus of the pressure-sensitive adhesive layer is in an appropriate range, whereby the polarizing film shrinks when the liquid crystal display device is exposed for a long time under high temperature and high humidity conditions. By doing so, the polarizing plate can be curled, and as a result, it is possible to improve the trouble that the optical characteristics such as white unevenness change. Specifically, the reference temperature 23
The relaxation elastic modulus at 15 ° C. and the relaxation time of 10 ⁵ seconds is 15 × 10 ⁵ dy.
n / cm ² or less is preferable, and more preferably 13 × 10 ⁵
dyn / cm ² or less, particularly preferably 10 × 10 ⁵
It is not more than dyn / cm ² . When the relaxation elastic modulus is low, cohesive failure of the pressure-sensitive adhesive layer proceeds, and when the relaxation elastic modulus is high, the shrinkage of the polarizing film cannot be sufficiently relaxed, and a failure such as warping of the liquid crystal display device occurs, which is not preferable.

As a concrete measuring method of the relaxation elastic modulus,
For a 1 mm pressure-sensitive adhesive layer (5 mm x 1.1 mm), a dynamic viscoelastic device (manufactured by Seiko Denshi KK) was used to obtain a frequency of 1 Hz.
At −100 to 200 ° C., the storage elastic modulus G ′ is measured, and the measured data is the dispersion data G ′ based on the frequency ω with 23 ° C. as the reference temperature using the time-temperature conversion rule consisting of the following WLF formula. Converted to (ω), and then generalized M
Relaxation elastic modulus Gk, relaxation time τk by axwell model
Then, the relaxation elastic modulus at a standard temperature of 23 ° C. and a relaxation time of 105 seconds is calculated. logaT = C1 (T−Ts) / (C2 + T−Ts) G ′ (ω) = ΣGk [(ω · τk) 2 / {1+ (ω · τ
k) 2}] τk = ηk / Gk Here, logaT is a shift factor, T is temperature, and coefficient C1 = 8.86, coefficient C2 = 101.6, characteristic temperature Ts = glass transition temperature Tg + 45 ° C. Also η
k is the relaxation viscosity.

<Liquid Crystal Display Device, etc.> The polarizing plate of the present invention can be used for various purposes. However, due to the property that the alignment axis is inclined with respect to the longitudinal direction, in particular, the inclination angle of the alignment axis is 40 to 40 with respect to the longitudinal direction. The polarizing film having an angle of 50 ° is a polarizing plate for LCD (eg, TN, STN, OCB, ROCB, ECB, CP.
(A, IPS, VA, etc. in all liquid crystal modes), and is preferably used for an antireflection circularly polarizing plate of an organic EL display. Also, various members such as λ / 4
It is also suitable when used in combination with a plate, a retardation film such as a λ / 2 plate, a viewing angle widening film, an antiglare film, a hard coat film and the like.

The basic structure of the reflective liquid crystal display device will be described below. For example, the reflective liquid crystal display device may include a lower substrate, a reflective electrode, a lower alignment film, a liquid crystal layer, an upper alignment film, a transparent electrode, an upper substrate, a λ / 4 plate, and a polarizing film in order from the bottom. The lower substrate and the reflective electrode form a reflector. The lower alignment film to the upper alignment film form a liquid crystal cell. λ / 4
The plate can be arranged at any position between the reflector and the polarizing film. In the case of color display, a color filter layer is further provided. The color filter layer is preferably provided between the reflective electrode and the lower alignment film or between the upper alignment film and the transparent electrode. A transparent electrode may be used instead of the reflective electrode, and another reflective plate may be attached. A metal plate is preferable as the reflector used in combination with the transparent electrode. If the surface of the reflector is smooth, only the specular reflection component may be reflected and the viewing angle may be narrowed. Therefore, it is preferable to introduce an uneven structure (described in Japanese Patent No. 275620) on the surface of the reflection plate. When the surface of the reflection plate is flat (instead of introducing an uneven structure on the surface), a light diffusion film may be attached to one side (cell side or outside) of the polarizing film.

The liquid crystal cell is a TN (twisted nematic)
Type, STN (Supper Twisted Nematic) type or HA
It is preferably an N (Hybrid Aligned Nematic) type. The twist angle of the TN type liquid crystal cell is preferably 40 to 100 °, more preferably 50 to 90 °, and most preferably 60 to 80 °. The value (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer and the thickness (d) of the liquid crystal layer is 0.1 to 0.5 μm.
Is preferable, and 0.2 to 0.4 μm is more preferable. The twist angle of the STN type liquid crystal cell is preferably 180 to 360 °, and 220
More preferably, the angle is from 270 ° to 270 °. The product of the refractive index anisotropy (Δn) of the liquid crystal layer and the thickness (d) of the liquid crystal layer (Δn
The value of d) is preferably 0.3 to 1.2 μm, more preferably 0.5 to 1.0 μm. In the HAN type liquid crystal cell, it is preferable that the liquid crystal is substantially vertically aligned on one substrate and the pretilt angle on the other substrate is 0 to 45 °. The product (Δnd) of the refractive index anisotropy (Δn) of the liquid crystal layer and the thickness (d) of the liquid crystal layer
The value of is preferably 0.1 to 1.0 μm,
More preferably, it is 0.3 to 0.8 μm. The substrate on the side of vertically aligning the liquid crystal may be the substrate on the reflection plate side or the substrate on the transparent electrode side.

The reflective liquid crystal display device is used in a normally white mode in which bright display is performed when the applied voltage is low and dark display when the applied voltage is high, and also in normally black mode in which bright display is applied when the applied voltage is low and bright display is applied when the applied voltage is high. be able to. Normally white mode is preferred.

[0130]

EXAMPLES In order to explain the present invention in detail, examples will be given below, but the present invention is not limited thereto.

Example 1 Both sides of a PVA film were washed with ion-exchanged water at a water flow of 2 l / min, and air blown to remove surface moisture to reduce foreign matter adhered to the surface to 0.5% or less. The PVA
The film was made of iodine 1.0 g / l and potassium iodide 60.
It is dipped in an aqueous solution of 0 g / l at 25 ° C. for 90 seconds, further dipped in an aqueous solution of 40 g / l boric acid and 30 g / l potassium iodide at 120 ° C. for 120 seconds, and then introduced into the tenter stretching machine of the form shown in FIG. Then, once stretched to 7.0 times in a 95 ° C. atmosphere of 40 ° C., and then contracted to 5.3 times, and then keeping the width constant,
After drying at 60 ° C., it was separated from the tenter. The water content of the PVA film before the start of stretching was 30%, and the water content after drying was 1.5%. The elastic modulus of the PVA film before stretching was 35 Mpa in the atmosphere of 40 ° C. and 95%.
The difference in transport speed between the left and right tenter clips was less than 0.05%, and the angle between the center line of the film introduced and the center line of the film sent to the next step was 0 °. Here, | L1-L2 | is 0.7 m, W is 0.7 m, and |
There was a relationship of L1-L2 | = W. Wrinkles and film deformation at the tenter exit were not observed.

The surface roughness Ra of the polarizing film at this time was measured by a surface roughness meter (Kosaka Laboratory Lt.
d. The result was 1.0 μm. Furthermore, an aqueous solution containing 3% of PVA (PVA-117H manufactured by Kuraray Co., Ltd.) and 4% of potassium iodide was used as an adhesive.
Fujitac (cellulose triacetate, retardation value 3. Fuji Photo Film Co., Ltd., saponified)
0 nm) and further heated at 60 ° C. for 30 minutes to obtain a polarizing plate having an effective width of 650 mm. Since the surface was smooth, the bonding was good.

The absorption axis of the obtained polarizing plate was tilted at 45 ° with respect to the longitudinal direction, and the slow axis of Fujitak was 4
It was tilted 5 °. The transmittance of this polarizing plate at 550 nm was 41.3%, and the polarization degree was 99.60%. The above polarizing plate whose absorption axis was oriented at 45 ° to the longitudinal direction was attached to a retardation film via an acrylic pressure-sensitive adhesive layer having a relaxation elastic modulus of 12 × 10 ⁴ dyn / cm. Then, aging was carried out at 50 ° C. and 5 atmospheric pressure for 20 minutes using an autoclave device. Furthermore, as shown in Fig. 2, 310 x 233m
When it was cut into m size, it was possible to obtain a polarizing plate having an absorption efficiency of 45 ° with respect to the side with an area efficiency of 91.5%. In addition, no color streak was visually observed. A durability test was conducted using the circularly polarizing plate thus obtained.

Example 2 As a pressure-sensitive adhesive composition, a relaxation elastic modulus of 12 × 10 ⁶ dyn / c
Example 1 above, except that the acrylic adhesive layer of m was used.
A circularly polarizing plate was prepared in accordance with the above, and a durability test was conducted.

Comparative Example 1 Using a commercially available polarizing plate, the relaxation elastic modulus was 12 × 10 ⁴ dyn.
The laminate was attached to a retardation film via an acrylic pressure-sensitive adhesive layer of / cm. Then, aging was carried out at 50 ° C. and 5 atmospheric pressure for 20 minutes using an autoclave device. A durability test was conducted using the circularly polarizing plate thus obtained.

The results are shown in Table 1. The durability test was conducted as follows. <Evaluation of polarization performance> Durability test: 60 ° C, 90%, 100h
Conducted under the conditions, 55 with Shimadzu's own spectrophotometer UV2100
The transmittance was measured when the absorption axes at 0 nm were made orthogonal to each other and were overlapped. The durability was evaluated from the ratio (%) of the fluctuation range of the transmittance with respect to the initial value. 0% to 1% or less ... ○, 1% or more and less than 5% ... △, 5% or more ... ×

<White unevenness> The polarizing plate prepared in the example was attached to a TN type liquid crystal display device, and after the durability test, a phenomenon in which a part of the display was removed due to the contraction of the polarizing plate was visually judged. No white unevenness is observed ... ○, Slightly observed ... △, Remarkable white unevenness is observed ... ×

[0138]

[Table 1]

As is clear from the comparison between Comparative Example 1 and Example 1, thermal contraction of the laminate is alleviated due to the different stretching axes of the polarizing film and the protective film, and two polarizing plates are arranged in a crossed Nicol state. In this case, increase in transmittance after the durability test and uneven whiteness can be suppressed. From the comparison between Example 1 and Example 2, further remarkable improvement was observed by increasing the degree of crosslinking of the pressure-sensitive adhesive layer.

Example 3 Next, as shown in FIG. 9, the iodine type polarizing plate 91 prepared in Example 2 was arranged as a display side polarizing plate on one side of the liquid crystal cell 97 of the LCD, and the liquid crystal was interposed via the adhesive layer 92. An LCD was prepared by laminating it on the cell 97. The LCD thus manufactured exhibits excellent brightness, viewing angle characteristics, and visibility, and is 40 ° C. and 30% RH.
No deterioration in display quality was observed even after 1 month of use.

[0141]

EFFECTS OF THE INVENTION According to the present invention, it is possible to obtain an obliquely oriented long circular polarizing plate which is excellent in durability, realizes circularly polarized light in a wide wavelength range, and can improve the yield. . Further, it is possible to obtain a circularly polarizing plate with a protective film, which has excellent durability and can realize circularly polarized light in a wide wavelength range. Further, by using the above-mentioned circularly polarizing plate, the deviation of the circular polarization degree on the short wavelength side is corrected, and the reflection type liquid crystal display device of excellent display quality without color deviation can be provided at low cost.

[Brief description of drawings]

FIG. 1 is a schematic perspective view showing a relationship between an optical film and a polarizing film in a circularly polarizing plate of the present invention.

FIG. 2 is a schematic plan view showing how a circularly polarizing plate of the present invention is punched.

FIG. 3 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.

FIG. 4 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.

FIG. 5 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.

FIG. 6 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.

FIG. 7 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.

FIG. 8 is a schematic plan view showing an example of the method of the present invention for obliquely stretching a polymer film.

9 is a schematic plan view showing the layer structure of the liquid crystal display device of Example 3. FIG.

[Explanation of symbols]

(A) Film introducing direction (b) Film conveying direction to the next step (a) Step of introducing the film (b) Step of stretching the film (c) Step of sending the stretched film to the next step A1 Bite position and starting point of film stretching (substantially holding start point: right) B1 Biting position into holding means of film (left) C1 Starting point of film stretching (substantially holding start point: left) Cx Film release position and film Stretching end point reference position (substantially holding release point: left) Ay Film stretching end point reference position (substantially holding release point:
Right) | L1-L2 | Stroke difference between left and right film holding means W Substantial width θ at the end of the stretching process of the film θ Angle between the stretching direction and the film advancing direction 11 Center line of the introducing side film 12 Center of the film sent to the next process Line 13 Trajectory of film holding means (left) 14 Trajectory of film holding means (right) 15 Introducing film 16 Film 17 and 17 'sent to the next process Left and right film holding start (biting) points 18 and 18' Left and right Departure point from film holding means 21 Center line of introduction side film 22 Center line of film sent to next step 23 Trail of film holding means (left) 24 Trail of film holding means (right) 25 Introduction side film 26 Next step Films 27, 27 'to be fed Left and right film holding start (biting) points 28, 28' Left and right film holding means detachment points 3 , 43, 53, 63 Trajectory of film holding means (left) 34, 44, 54, 64 Trajectory of film holding means (right) 35, 45, 55, 65 Introducing side film 36, 46, 56, 66 Send to next process Film 70 Optical film 71, 71 'Slow axis 74 of optical film Adhesive layer or adhesive layer 80 Polarizing film 81 Absorption axis 82 of polarizing film Longitudinal direction 83 Transverse direction 90 Circular polarizing plate 91 Iodine-based polarizing plate 92 Adhesive Layer 97 Liquid crystal cell 98 Backlight

   ─────────────────────────────────────────────────── ─── Continued front page    F-term (reference) 2H049 BA02 BA03 BA06 BA27 BA42                       BB03 BB43 BB52 BC03 BC14                       BC22                 2H091 FA08X FA11X FA14Y FA37Y                       FA37Z FB02 FB11 FC01                       FC05 FC07 FC21 FC22 FC24                       FC29 GA03 HA07 HA10 KA01                       KA02 LA07 LA12 LA16 LA18                       LA19 LA30

Claims (3)

[Claims] 1. A length in which at least one optical film is coated on at least one surface of a polarizing film whose absorption axis is neither parallel nor perpendicular to the longitudinal direction, and which has a pressure-sensitive adhesive layer on the outside of at least one polarizing film or optical film. The length of the polarizing plate is such that the angle between the absorption axis of the polarizing film and the slow axis of at least one optical film is 10 ° or more and less than 90 °, and after the durability test, the circular polarizing plate is irradiated with light of 450 nm. The ratio between the transmittance in the direction parallel to the transmission axis and the transmittance in the direction perpendicular to the transmission axis when light enters from the polarizing film side satisfies the following formula (I), A circularly polarizing plate characterized in that the ratio of the transmittance in the direction parallel to the transmission axis and the transmittance in the direction perpendicular to the transmission axis when incident from the side satisfies the following formula (II). (I) 0.95 <T // (450) / T⊥ (450) ≦
1.05 (II) 0.95 <T // (590) / T⊥ (590) ≦
1.05 [wherein T // (450) is the transmittance in the direction parallel to the transmission axis when 450 nm light is incident from the polarizing film side;
T⊥ (450) is the transmittance in the direction perpendicular to the transmission axis when 450 nm light is incident from the polarizing film side; T //
(590) is the transmittance in the direction parallel to the transmission axis when light of 590 nm is incident from the polarizing film side; and T⊥
(590) is the transmittance in the direction perpendicular to the transmission axis when light of 590 nm is incident from the polarizing film side]. 2. A polarizing film having at least one surface on at least one side.
A circularly polarizing plate having a sheet of protective film and having an adhesive layer on the outside of at least one of the polarizing film or the protective film,
The angle between the absorption axis of the polarizing film and the slow axis of the protective film is 10 ° or more and less than 90 °, and the circularly polarizing plate has 450 after the durability test.
The ratio of the transmittance in the direction parallel to the transmission axis and the transmittance in the direction perpendicular to the transmission axis when light of nm wavelength is incident from the polarizing film side satisfies the formula (I) according to claim 1, and The ratio between the transmittance in the direction parallel to the transmission axis and the transmittance in the direction perpendicular to the transmission axis when light of 590 nm is incident from the polarizing film side is defined by:
A circularly polarizing plate satisfying the formula (II) described. 3. A polarizing plate arranged on at least one side of a liquid crystal cell, a circularly polarizing plate obtained by cutting out the long circularly polarizing plate according to claim 1, or the circularly polarizing plate according to claim 2 being adhered and used. Liquid crystal display device characterized by.