JP2011017017A - Saturated norbornene film and method for producing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a saturated norbornene film capable of improving minute display nonuniformity when a retardation plate is incorporated in a liquid crystal display element.SOLUTION: A method for producing the saturated norbornene film includes a process for vertically drawing a saturated norbornene resin, which has a vertical-to-lateral size ratio of 3, to 1.1-2.5 times. As the saturated norbornene resin, following resins are available: (1) a resin obtained by hydrogenating a ring-opened polymer (including a copolymer) of norbornene monomers after performing polymer modification such as maleic acid addition and cyclopentadiene addition if necessary; (2) a resin obtained by addition polymerization of the norbornene monomers; and (3) a resin obtained by addition copolymerization of the norbornene monomers with olefin monomers such as ethylene and α-olefin.

Description

  The present invention relates to a saturated norbornene film having good optical uniformity and a method for producing the same.

Conventionally, a saturated norbornene resin is stretched and used as a retardation film of a liquid crystal display element, a saturated norbornene film in which an in-plane retardation value (Re value) and a retardation value in the thickness direction (Rth value) are expressed, Enlarging the viewing angle has been implemented.
As a method of stretching such a saturated norbornene resin, a method of stretching in the longitudinal (longitudinal) direction (longitudinal stretching) and a method of stretching in the transverse (width) direction (transverse stretching), or a method of stretching in the longitudinal and lateral directions simultaneously. (Simultaneous stretching) is known.
Among these, longitudinal stretching has been conventionally used in many cases because the apparatus is compact. FIG. 2 shows an example of a longitudinal stretching apparatus conventionally used. A saturated norbornene resin (4) is glass transition temperature (Tg) between two or more pairs of nip rolls (5, 5). The film is heated as described above and stretched by increasing the conveyance speed on the outlet side from the conveyance speed of the nip roll on the inlet side.
Further, for example, as a method of stretching a saturated norbornene resin, Patent Document 1 describes that the variation in the Re value can be reduced by reducing the temperature unevenness during stretching.
However, when the stretched film obtained by the methods described therein is used as a retardation film, fine planar unevenness appears and improvement has been desired.

JP 2001-42130 A

  An object of the present invention is to solve the above-mentioned problem, that is, when a retardation plate using a saturated norbornene film obtained by stretching a saturated norbornene resin is incorporated into a liquid crystal display element. The display unevenness is improved.

The above object of the present invention has been achieved by the following constitution.
(1) A saturated norbornene film having an adhesion mark of 10 points / m ² or less, an in-plane retardation value (Re value) of 0 nm to 500 nm, and a thickness direction retardation value (Rth value) of 30 nm to 500 nm.
(2) The saturated norbornene film as described in (1) above, wherein both the Re value and the Rth value have a variation rate in the width direction and the longitudinal direction of 5% or less.
(3) The saturated norbornene film according to (1) or (2), which is formed by a melt film forming method.
(4) The saturated norbornene film according to the above (1) or (2), which is formed by a solution casting method.
(5) The saturated norbornene film according to the above (4), which is obtained by stretching a saturated norbornene resin in which the residual amount of the solvent for dissolving the saturated norbornene resin used in the solution casting method is 3% by weight or less.
(6) The saturated norbornene film according to any one of (1) to (5) above, wherein the Rth value is larger than the Re value.
(7) A polarizing plate comprising a polarizing layer and at least one layer of the saturated norbornene film according to any one of (1) to (6) provided on the polarizing layer.
(8) An optical compensation film for a liquid crystal display panel comprising the saturated norbornene film according to any one of (1) to (6) above.
(9) An antireflection film comprising the saturated norbornene film according to any one of (1) to (6) above.

(10) A method for producing a saturated norbornene film comprising a step of longitudinally stretching 1.1 to 2.5 times in a saturated norbornene resin having an aspect ratio / width ratio of more than 2 and 50 or less.
(11) The method for producing a saturated norbornene film according to (10), wherein the longitudinal stretching is performed using two or more pairs of nip rolls installed outside the stretching zone.
(12) The method for producing a saturated norbornene film according to the above (10) or (11), wherein the longitudinal stretching is performed with a tenter.
(13) The temperature of the two or more pairs of nip rolls is (Tg−150) ° C. or more and less than (Tg) ° C., and the temperature of the stretching zone is (Tg) to (Tg + 100) ° C. The manufacturing method of the saturated norbornene film as described in (12).
(14) The method for producing a saturated norbornene film according to any one of (10) to (13), wherein the stretching is longitudinal stretching while being conveyed in a non-contact manner in the heat treatment zone.

  Fine display unevenness can be improved when a retardation plate obtained by stretching a saturated norbornene film is incorporated in a liquid crystal display element.

An example of a preferred longitudinal stretching zone used in the present invention is shown. An example of the longitudinal stretching zone conventionally employed is shown.

  Hereinafter, the contents of the present invention will be described in detail. In the present specification, “to” is used to mean that the numerical values described before and after it are included as a lower limit value and an upper limit value. In the present invention, Tg indicates the glass transition temperature of a saturated norbornene resin or film unless otherwise specified.

In the present invention, as a result of analyzing the cause of the fine display unevenness that appears when used in a liquid crystal display device, it has been clarified that this is caused by adhesion marks between the nip roll and the saturated norbornene film.
The saturated norbornene film of the present invention is stretched at a high magnification in order to develop an in-plane retardation value (Re value) and a retardation value in the thickness direction (Rth value). These Re value (nm) and Rth value (nm) are expressed by the following equations.
Formula (1) Re = | n (MD) −n (TD) | × T
Formula (2) Rth = | {(n (MD) + n (TD)} / 2} −n (TH) | × T
(In formulas (1) and (2), n (MD), n (TD), and n (TH) represent the refractive index in the longitudinal direction, the width direction, and the thickness direction, respectively, and T is expressed in nm. Indicates the thickness of the film.)

In order to stretch at a high magnification, it is preferable to stretch at a high temperature. However, longitudinal stretching is generally achieved by changing the conveying speed between two or more pairs of nip rolls, and is narrow, for example, as shown in FIG. Not only the saturated norbornene resin (film) but also the nip roll at the roll interval (that is, the nip roll interval (L ′) used for stretching is smaller and the aspect ratio (L ′ / W) is smaller than the width (W) of the saturated norbornene film). Is carried out at a high temperature. This is because the film is stretched rapidly in a short period of time, so that the saturated norbornene resin is rapidly heated from the nip roll, and is also acting as a preheating roll.
Under such conditions, adhesion failure is very likely to occur. Adhesive failure is a pattern of “C” shape (a bird's foot shape) of about several millimeters that is confirmed on the film surface. It adheres when the film comes into contact with the stretching roll, and adheres when the film leaves. Starting from a point, the film surface is radially spread when the film surface is stripped radially. When stretching at a high magnification, the film is often stretched at a high temperature, and such a sticking failure appears remarkably. Such adhesion marks are preferably 10 points / m ² or less, more preferably 8 points / m ² or less, and still more preferably 5 points / m ² or less.

  In order to deal with such a sticking failure, the present invention is characterized in that first, the aspect ratio is increased and the film is stretched. That is, if the aspect ratio is short and stretching is performed at a short distance (short time), a large stretching stress is required because the stretching is performed rapidly, and as a result, the adhesion failure occurring on the nip roll is easily amplified. That is, after adhesion, a large tension is applied rapidly, so that the area of the adhesion mark is easily increased. On the other hand, when the aspect ratio is large, the span to be stretched becomes long. Therefore, the span is stretched slowly during this period, and the adhesion is difficult to be amplified, and is difficult to detect visually. The preferred aspect ratio is more than 2 and 50 or less, more preferably 3 to 40, still more preferably 4 to 20. A preferred stretching temperature is (Tg) to (Tg + 100) ° C., more preferably (Tg + 2) to (Tg + 50) ° C., and further preferably (Tg + 5) to (Tg + 30) ° C. A preferable draw ratio is 1.1 to 3 times, more preferably 1.2 to 2.5 times, and still more preferably 1.3 to 2 times. By such stretching, the Re value is 0 to 500 nm, more preferably 10 to 400 nm, further preferably 15 nm to 300 nm, the Rth value is 30 to 500 nm, more preferably 50 to 400 nm, still more preferably 70 to 350 nm. Variations in the width direction and the longitudinal direction of the Re value and the Rth value can both be 5% or less, more preferably 4% or less, and even more preferably 3% or less. That is, when an adhesion failure occurs, uneven stretching occurs around that region, and accordingly, unevenness in the Re value and Rth value also occurs. Therefore, these can also be reduced by improving the uneven tackiness of the present invention.

Furthermore, the present invention is characterized in that a nip roll is taken out of the stretching zone that needs to be heated as a countermeasure against the second adhesive failure. That is, as shown in FIG. 1, nip rolls (1, 3) are provided outside the stretching zone (2). The temperature of the nip roll is preferably (Tg−150) ° C. or more and less than (Tg) ° C., more preferably (Tg−120) to (Tg−2) ° C., more preferably on both the inlet side and the outlet side. Is (Tg-100) to (Tg-5) ° C. When stretching with a long span as in the present invention, it is not necessary to heat the nip roll and heat the saturated norbornene resin rapidly as in the prior art, and it is possible to stretch while heating slowly in a long stretching zone. The nip roll can be cooled.
In such a longitudinal stretching zone, it is more preferable to carry it in a non-contact manner without bringing it into contact with a roll or the like because it is difficult to cause adhesion.

  Re and Rth values can be expressed by stretching as described above, but among Re and Rth values, those satisfying Re <Rth are more preferable, and more preferably satisfying Re × 2 <Rth Is more preferable. In order to realize such a high Rth value and low Re value, it is preferable to stretch the product that has been longitudinally stretched as described above in the transverse (width) direction. That is, the difference in orientation between the vertical direction and the horizontal direction is the difference in the in-plane retardation value (Re value). By stretching in the horizontal direction that is the orthogonal direction in addition to the vertical direction, The difference can be reduced and the plane orientation (Re value) can be reduced. On the other hand, since the area magnification increases by stretching in addition to the length, the thickness decreases. This is because the orientation in the thickness direction increases with this, and the Rth value can be increased. For stretching in the transverse direction, a method of holding both ends with a chuck and widening with a tenter is generally used. The magnification of such transverse stretching is preferably more than 1 and not more than 3.0 times, more preferably 1.0 to 2.5 times, still more preferably 1.05 to 2.2 times, still more preferably 1 .1 to 2 times. The preferred stretching temperature is (Tg) to (Tg + 100) ° C., more preferably (Tg + 2) to (Tg + 50) ° C., more preferably (Tg + 4) to (Tg + 50) ° C., and still more preferably (Tg + 4) to (Tg + 40). ° C, most preferably (Tg + 4) to (Tg + 30) ° C.

  As the saturated norbornene resin employed in the present invention, the solution film forming method and the melt film forming method described later can be applied, but the saturated norbornene resin-A is more preferably used for the melt film forming method, More preferably, it is used for the solution casting method.

(Saturated norbornene resin-A)
As an example of the saturated norbornene resin used in the present invention, (1) a ring-opening polymer of a norbornene monomer (including a copolymer) is subjected to polymer modification such as maleic acid addition or cyclopentadiene addition as necessary. And (2) a resin obtained by addition polymerization of a norbornene monomer and (3) a resin obtained by addition copolymerization with a norbornene monomer and an olefin monomer such as ethylene or α-olefin. be able to. The polymerization method and the hydrogenation method can be performed by conventional methods.
Examples of the norbornene-based monomer include norbornene and its alkyl group and / or alkylidene group-substituted products such as 5-methyl-2-norbornene, 5-dimethyl-2-norbornene, 5-ethyl-2-norbornene, 5- Butyl-2-norbornene, 5-ethylidene-2-norbornene, and the like, polar group-substituted products such as halogen; dicyclopentadiene, 2,3-dihydrodicyclopentadiene, etc .; dimethanooctahydronaphthalene, its alkyl and / or Alkylidene-substituted products and polar group-substituted products such as halogen, for example, 6-methyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6 -Ethyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-oct Hydronaphthalene, 6-ethylidene-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-chloro-1,4: 5,8-dimethano -1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-cyano-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a -Octahydronaphthalene, 6-pyridyl-1,4: 5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 6-methoxycarbonyl-1,4: 5 8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, etc .; adducts of cyclopentadiene and tetrahydroindene, etc .; 3-pentamers of cyclopentadiene, such as 4,9 : 5,8-dimethano-3a, 4,4a, , 8,8a, 9,9a-octahydro-1H-benzoindene, 4,11: 5,10: 6,9-trimethano-3a, 4,4a, 5,5a, 6,9,9a, 10,10a, 11,11a-dodecahydro-1H-cyclopentanthracene; and the like.

(Saturated norbornene resin-B)
Moreover, as a saturated norbornene resin, what is represented by the following general formula (1)-(4) can be mentioned, Among these, what is represented by the following general formula (1) is especially preferable.

（一般式（１）〜（３）中、Ａ、Ｂ、ＣおよびＤは、水素原子または１価の有機基を示し、これらのうち少なくとも１つは極性基である。）

(In the general formulas (1) to (3), A, B, C and D represent a hydrogen atom or a monovalent organic group, and at least one of them is a polar group.)

The weight average molecular weight of these saturated norbornene resins is usually preferably 5,000 to 1,000,000, more preferably 8,000 to 200,000.
Examples of the saturated norbornene resin of the present invention include, for example, JP-A-60-168708, JP-A-62-252406, JP-A-62-2252407, JP-A-2-133413, JP-A-63. Examples thereof include resins described in JP-A-145324, JP-A-63-264626, JP-A-1-240517, and JP-B-57-8815.
Among these resins, a hydrogenated polymer obtained by hydrogenating a ring-opening polymer of a norbornene monomer is particularly preferable.
The glass transition temperature (Tg) of these saturated norbornene resins is preferably 120 ° C. or higher, more preferably 140 ° C. or higher, and the saturated water absorption is preferably 1% by weight or lower, more preferably 0.8. The amount is 8% by weight or less. The glass transition temperature (Tg) and saturated water absorption of the saturated norbornene resins represented by the general formulas (1) to (4) can be controlled by selecting the type of the substituents A, B, C, and D. .

  As the saturated norbornene resin of the present invention, at least one tetracyclododecene derivative represented by the following general formula (5) is used alone, or the unsaturated compound capable of copolymerizing with the tetracyclododecene derivative. A hydrogenated polymer obtained by hydrogenating a polymer obtained by metathesis polymerization with a cyclic compound may be used.

（一般式（５）中、Ａ、Ｂ、ＣおよびＤは、水素原子または１価の有機基を示し、これらのうち少なくとも１つは極性基である。）

(In general formula (5), A, B, C and D represent a hydrogen atom or a monovalent organic group, and at least one of them is a polar group.)

In the tetracyclododecene derivative represented by the above general formula (5), at least one of A, B, C and D is a polar group, so that the film is superior in adhesion to other materials, heat resistance, and the like. Can be obtained. Further, the polar group is a group represented by — (CH ₂ ) _n COOR (where R is a hydrocarbon group having 1 to 20 carbon atoms, and n is an integer of 0 to 10). The resulting hydrogenated polymer (polarizing film substrate) is preferred because it has a high glass transition temperature. In particular, the polar substituent represented by — (CH ₂ ) _n COOR is contained in one molecule of the tetracyclododecene derivative represented by the general formula (5) to reduce the water absorption rate. To preferred. In the above polar substituent, it is preferable in that the hygroscopicity of the obtained hydrogenated polymer decreases as the number of carbon atoms of the hydrocarbon group represented by R increases, but the balance with the glass transition temperature of the obtained hydrogenated polymer is good. From this point, the hydrocarbon group is preferably a chain alkyl group having 1 to 4 carbon atoms or a (poly) cyclic alkyl group having 5 or more carbon atoms, and particularly preferably a methyl group, an ethyl group, or a cyclohexyl group. preferable.

Furthermore, the tetracyclododecene derivative of the general formula (5) in which a hydrocarbon group having 1 to 10 carbon atoms is bonded as a substituent to a carbon atom to which a group represented by — (CH ₂ ) _n COOR is bonded, This is preferable because the resulting hydrogenated polymer has low hygroscopicity. In particular, the tetracyclododecene derivative of the general formula (5) in which the substituent is a methyl group or an ethyl group is preferable in terms of easy synthesis. Specifically, 8-methyl-8-methoxycarbonyltetracyclo [4,4,0,12.5, 17.10] dodec-3-ene is preferable. These tetracyclododecene derivatives and mixtures of unsaturated cyclic compounds copolymerizable therewith are described, for example, in JP-A-4-77520, page 4, upper right column, line 12 to page 6, lower right column, line 6. Metathesis polymerization and hydrogenation can be carried out by the prepared method.
These norbornene resins preferably have an intrinsic viscosity (ηinh) measured at 30 ° C. in chloroform of 0.1 to 1.5 dL / g, more preferably 0.4 to 1.2 dL / g. It is. Moreover, as a hydrogenation rate of a hydrogenated polymer, the value measured by 60 MHz and 1H-NMR shall be 50% or more, Preferably it is 90% or more, More preferably, it is 98% or more. The higher the hydrogenation rate, the more the saturated norbornene film obtained has better stability to heat and light. The gel content contained in the hydrogenated polymer is preferably 5% by weight or less, and more preferably 1% by weight or less.

The saturated norbornene resin of the present invention includes known antioxidants such as 2,6-di-t-butyl-4-methylphenol, 2,2′-dioxy-3,3′-di-t-butyl- 5,5′-dimethylphenylmethane, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane, 1,1,3-tris (2-methyl-4-hydroxy) -5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, stearyl-β- (3 5-di-t-butyl-4-hydroxyphenyl) propionate, 2,2′-dioxy-3,3′-di-t-butyl-5,5′-diethylphenylmethane, 3,9-bis [1, 1-dimethyl-2- [β- (3 -T-butyl-4-hydroxy-5-methylphenyl) propionyloxy] ethyl], 2,4,8,10-tetraoxospiro [5,5] undecane, tris (2,4-di-t-butylphenyl) ) Phosphite, cyclic neopentanetetraylbis (2,4-di-t-butylphenyl) phosphite, cyclic neopentanetetraylbis (2,6-di-t-butyl-4-methylphenyl) phos Phyto, 2,2-methylenebis (4,6-di-t-butylphenyl) octyl phosphite; stable by adding UV absorbers such as 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone Can be Further, additives such as a lubricant can be added for the purpose of improving processability.
The addition amount of these antioxidants is 0.1-3 weight part normally with respect to 100 weight part of saturated norbornene-type resin, Preferably it is 0.2-2 weight part.
Furthermore, you may add various additives, such as anti-aging agents, such as a phenol type and a phosphorus type, an antistatic agent, and an ultraviolet absorber, to saturated norbornene-type resin. In particular, since the liquid crystal is usually deteriorated by ultraviolet rays, it is preferable to add an ultraviolet absorber when other protective measures such as laminating an ultraviolet protective filter are not taken. As the ultraviolet absorber, a benzophenone-based ultraviolet absorber, a benzotriazole-based ultraviolet absorber, an acrylonitrile-based ultraviolet absorber, or the like can be used. Among them, a benzophenone-based ultraviolet absorber is preferable, and the addition amount is usually 10 ˜100,000 ppm, preferably 100 to 10,000 ppm. Moreover, when producing a sheet | seat by the solution casting method, in order to make surface roughness small, addition of a leveling agent is preferable. As the leveling agent, for example, a coating leveling agent such as a fluorine-based nonionic surfactant, a special acrylic resin leveling agent, or a silicone leveling agent can be used, and among them, those having good compatibility with a solvent are preferable. The addition amount is usually 5 to 50,000 ppm, preferably 10 to 20,000 ppm.

In the present invention, other cycloolefins capable of ring-opening polymerization can be used in combination as long as the object of the present invention is not impaired. Specific examples of such cycloolefins are preferably compounds having one reactive double bond such as cyclopentene, cyclooctene, and 5,6-dihydrodicyclopentadiene.
These saturated norbornene resins can be formed into a film by either solution casting or melt casting.
(Solution casting)
The concentration of the resin when the saturated norbornene resin of the present invention is dissolved in a solvent is preferably 3 to 50% by weight, more preferably 5 to 40% by weight, and still more preferably 10 to 35% by weight. The viscosity of the solution at room temperature is usually 1 to 1,000,000 (mPa · s), preferably 10 to 100,000 (mPa · s), and more preferably 100 to 50,000 (mPa · s). S), particularly preferably 1,000 to 40,000 (mPa · s).
Solvents used include aromatic solvents such as benzene, toluene, xylene, cellosolve solvents such as methyl cellosolve, ethyl cellosolve, 1-methoxy-2-propanol, diacetone alcohol, acetone, cyclohexanone, methyl ethyl ketone, 4-methyl. -2-pentanone, cyclohexanone, ethylcyclohexanone, ketone solvents such as 1,2-dimethylcyclohexane, ester solvents such as methyl lactate and ethyl lactate, 2,2,3,3-tetrafluoro-1-propanol, methylene chloride And halogen-containing solvents such as chloroform, ether solvents such as tetrahydrofuran and dioxane, and alcohol solvents such as 1-pentanol and 1-butanol.
In addition to the above, the SP value (solubility parameter) is usually 10 to 30 (MPa 1/2), preferably 10 to 25 (MPa 1/2), more preferably 15 to 25 (MPa 1/2), particularly preferably 15. It is preferred to use a solvent in the range of ~ 20 (MPa 1/2). The said solvent can be used individually or in combination of 2 or more types. When using 2 or more types of solvent together, it is preferable to make the range of SP value as a mixture into the said range. At this time, the value of the SP value as a mixture can be obtained from the weight ratio. For example, in the case of two kinds of mixtures, the weight fraction of each solvent is W1, W2, and the SP value is SP1, SP2. Then, the SP value of the mixed solvent can be obtained as a value calculated by the following formula: SP value = W1 · SP1 + W2 · SP2.
Furthermore, a leveling agent may be added to improve the surface smoothness of the saturated norbornene film. Any general leveling agent can be used. For example, a fluorine-based nonionic surfactant, a special acrylic resin leveling agent, a silicone leveling agent, and the like can be used.

As a method for producing the saturated norbornene film of the present invention by a solvent casting method, the above solution may be a metal drum, steel belt, polyester film such as polyethylene terephthalate (PET) or polyethylene naphthalate (PEN) using a die or a coater, In general, a method of coating on a substrate such as a polytetrafluoroethylene belt, and then drying and removing the solvent to peel off the film from the substrate.
Alternatively, the resin solution can be applied to the substrate using means such as spraying, brushing, roll spin coating, dipping, etc., and then the solvent is dried and removed to peel the film from the substrate. The thickness and surface smoothness may be controlled by repeating the coating.
Moreover, when using a polyester film as a base material, you may use the film by which surface treatment was carried out. As a surface treatment method, a hydrophilic treatment method generally performed, for example, a method of laminating an acrylic resin or a sulfonate group-containing resin by coating or lamination, or a hydrophilic property of the film surface by corona discharge treatment or the like. The method etc. which improve are mentioned.

The drying (solvent removal) step of the solvent casting method is not particularly limited and can be carried out by a generally used method, for example, a method of passing through a drying furnace through a large number of rollers. If bubbles are generated as a result of evaporation, the characteristics of the film are remarkably deteriorated. Therefore, in order to avoid this, it is preferable to control the temperature or air volume in each step by making the drying step into a plurality of steps of two or more steps.
Further, this longitudinal stretching is carried out with the solvent remaining in the saturated norbornene resin being usually 10% by weight or less, preferably 5% by weight or less, and more preferably 3% by weight or less. This is because adhesion is more likely to occur in the presence of the residual solvent. Even more preferably, it is 2% by mass or less, and most preferably 1% by mass or less.
In particular, the residual solvent amount when used as an optical film is preferably 1% by weight or less, particularly preferably 0.5% by weight or less. By reducing the residual solvent in this way, it is preferable because the adhesion trace failure can be further reduced.
The thickness of the saturated norbornene film produced by the above production method is preferably 10 to 300 μm, more preferably 20 to 250 μm, still more preferably 30 to 200 μm, and the thickness distribution is within ± 8% of the average value. Preferably, it is within ± 5%, more preferably within ± 3%. The variation in thickness per cm is usually 5% or less, preferably 3% or less, more preferably 1% or less, and particularly preferably 0.5% or less.

(Melting film formation)
Saturated norbornene resin pellets are put into a melt extruder, dehydrated at 100 ° C. or higher and 200 ° C. or lower for 1 minute or longer and 10 hours or shorter, and then kneaded and extruded. For kneading, a single-screw or twin-screw extruder can be used.
(1) Drying The saturated norbornene resin may be used as it is, but it is more preferable to use a pelletized one in order to reduce the thickness fluctuation of the film.
The resin has a moisture content of 1% or less, more preferably 0.5% or less, and is then charged into a hopper of a melt extruder. At this time, the hopper is set to (Tg-50) to (Tg + 30) ° C, more preferably (Tg-40) to (Tg + 10) ° C, and further preferably (Tg-30) to (Tg) ° C. Thereby, the re-adsorption of the water | moisture content in a hopper can be suppressed, and the said drying efficiency can be expressed more easily.
(2) Kneading extrusion 240-320 degreeC, More preferably, 250-310 degreeC, More preferably, it is 260-300 degreeC, The temperature of a casting drum is 80-170 degreeC, More preferably, it is 90-160 degreeC, More preferably, it is 100- Knead and melt at 150 ° C. At this time, the melting temperature may be a constant temperature, or may be divided into several parts and controlled. A preferable kneading time is 2 to 60 minutes, more preferably 3 to 40 minutes, and further preferably 4 to 30 minutes. Furthermore, it is also preferable to carry out the inside of the melt extruder in an inert (nitrogen or the like) air flow or while evacuating using a vented extruder.

(3) Casting The melted resin is passed through a gear pump, and after removing the pulsation of the extruder, it is filtered with a metal mesh filter or the like, and extruded from a T-shaped die attached behind it into a sheet on a cooling drum. Extrusion may be performed in a single layer, or multiple layers may be extruded using a multi-manifold die or a feed block die. At this time, the thickness unevenness in the width direction can be adjusted by adjusting the distance between the lips of the die.
Thereafter, it is extruded onto a casting drum. At this time, it is preferable to use a method such as an electrostatic application method, an air knife method, an air chamber method, a vacuum nozzle method, or a touch roll method to increase the adhesion between the casting drum and the melt-extruded sheet. Such an adhesion improving method may be performed on the entire surface of the melt-extruded sheet or a part thereof.
The casting drum is preferably 60 to 160 ° C, more preferably 70 to 150 ° C, and still more preferably 80 to 150 ° C. Then, it peels off from a casting drum, winds up after passing through a nip roll. The winding speed is preferably 10 m / min to 100 m / min, more preferably 15 m / min to 80 m / min, still more preferably 20 m / min to 70 m / min.
The film forming width is 1 m to 5 m, more preferably 1.2 m to 4 m, and still more preferably 1.3 m to 3 m. The thickness of the unstretched film thus obtained is preferably 30 to 400 μm, more preferably 40 to 300 μm, and still more preferably 50 to 200 μm.
The sheet thus obtained is preferably trimmed at both ends and wound up. The trimmed portion is re-processed as a raw material for the same type of film or as a raw material for a film of a different type after being pulverized or subjected to processing such as granulation or depolymerization / repolymerization as necessary. May be used. Moreover, it is also preferable from a viewpoint of scratch prevention to attach a lami film to at least one surface before winding.
The thickness unevenness of the saturated norbornene film formed by the above method is preferably 0 to 2% in both the longitudinal direction and the width direction, more preferably 0 to 1.5%, and further preferably 0 to 1%. The method is stretched to obtain the saturated norbornene film of the present invention.

(Processing of saturated norbornene film)
The saturated norbornene film stretched uniaxially or biaxially by the above-described method may be used alone or in combination with a polarizing plate, and a liquid crystal layer or a layer with a controlled refractive index ( A low reflection layer) or a hard coat layer may be provided. These can be achieved by the following steps.
(1) Surface treatment The saturated norbornene film can be improved in adhesion with each functional layer (for example, undercoat layer and back layer) by performing the surface treatment. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment can be used. The glow discharge treatment here may be low-temperature plasma that occurs in a low-pressure gas of 10 ^{−3 to} 20 Torr, and plasma treatment under atmospheric pressure is also preferable. A plasma-excitable gas is a gas that is plasma-excited under the above conditions, and includes chlorofluorocarbons such as argon, helium, neon, krypton, xenon, nitrogen, carbon dioxide, tetrafluoromethane, and mixtures thereof. It is done. Details of these are described in detail on pages 30 to 32 in the Journal of the Invention Association (Technology No. 2001-1745, issued on March 15, 2001, Invention Association). Note that, in the plasma treatment at atmospheric pressure which has been attracting attention in recent years, for example, irradiation energy of 20 to 500 Kgy is used under 10 to 1000 Kev, and more preferably irradiation energy of 20 to 300 Kgy is used under 30 to 500 Kev. Of these, glow discharge treatment, corona treatment, and flame treatment are particularly preferred.
It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be coated after the above surface treatment or may be coated without the surface treatment. Details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention).
These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

(2) Application of functional layer The saturated norbornene film of the present invention is described in detail on pages 32 to 45 in the Japan Society for Invention and Technology (public technical number 2001-1745, published on March 15, 2001, Japan Society for Invention). It is preferable to combine the functional layers. Among them, the norbornene resin of the present invention is preferably provided with a polarizing layer (polarizing plate), an optical compensation layer (optical compensation sheet), or an antireflection layer (antireflection film). .
(2-1) Application of polarizing layer (preparation of polarizing plate)
(2-1-1) Material used Currently, a commercially available polarizing layer immerses the stretched polymer in a solution of iodine or dichroic dye in a bath, and allows the iodine or dichroic dye to penetrate into the binder. Generally, it is produced by this. As the polarizing plate, a coating type polarizing plate represented by Optiva Inc. can also be used. Iodine and dichroic dye in the polarizing plate exhibit deflection performance by being oriented in the binder. As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl). For example, the compound as described in Invention Association public technique, public technical number 2001-1745, page 58 (issue date March 15, 2001) can be mentioned.

  As the binder of the polarizing plate, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the binder include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohols and modified polyvinyl alcohols described in JP-A-8-338913, paragraph [0022], poly (N-methylolacrylamide). ), Polyester, polyimide, vinyl acetate copolymer, carboxymethyl cellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol, modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are most preferred. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000. The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509 and JP-A-9-316127. Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

The lower limit of the binder thickness is preferably 10 μm. The upper limit of the thickness is preferably as thin as possible from the viewpoint of light leakage of the liquid crystal display device. It is preferably not more than a commercially available polarizing plate (about 30 μm), preferably 25 μm or less, and more preferably 20 μm or less.
The binder of the polarizing plate may be crosslinked. A polymer or monomer having a crosslinkable functional group may be mixed in the binder, or a crosslinkable functional group may be imparted to the binder polymer itself. Crosslinking can be performed by light, heat, or pH change, and a binder having a crosslinked structure can be formed. The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (eg, boric acid, borax) can also be used as a crosslinking agent. The addition amount of the crosslinking agent in the binder is preferably 0.1 to 20% by mass with respect to the binder. The orientation of the polarizing element and the wet heat resistance of the polarizing plate are improved.
Even after the crosslinking reaction is completed, the unreacted crosslinking agent is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By doing in this way, a weather resistance improves more.

(2-1-2) Stretching of polarizing layer The polarizing plate is preferably dyed with iodine or a dichroic dye after stretching the polarizing layer (stretching method) or rubbing (rubbing method).
In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. Stretching may be performed in parallel to the MD direction (parallel stretching) or may be performed in an oblique direction (oblique stretching). These stretching operations may be performed once or divided into several times. By dividing into several times, it is possible to stretch more uniformly even at high magnification.
a) Parallel stretching method Prior to stretching, the PVA film is swollen. The degree of swelling is 1.2 to 2.0 times (weight ratio before swelling and after swelling). Thereafter, the film is stretched at a bath temperature of 15 to 50 ° C., particularly 17 to 40 ° C. in an aqueous medium bath or a dye bath for dissolving a dichroic substance while being continuously conveyed through a guide roll or the like. Stretching can be achieved by gripping with two pairs of nip rolls and increasing the conveyance speed of the subsequent nip roll to be higher than that of the previous nip roll. The draw ratio is based on the length ratio after stretching / initial state (hereinafter the same), but the preferred draw ratio is 1.2 to 3.5 times, especially 1.5 to 3.0 times from the viewpoint of the above-mentioned effects. is there. Then, it is made to dry at 50-90 degreeC, and a polarizing plate is obtained.

b) Diagonal Stretching Method For this purpose, a method of stretching using a tenter projecting in an oblique direction inclined in an oblique direction described in JP-A-2002-86554 can be used. Since this stretching is performed in the air, it is necessary to make it easy to stretch by adding water in advance. A preferable moisture content is 5% to 100%, more preferably 10 to 100%.
The temperature during stretching is preferably 40 to 90 ° C, more preferably 50 to 80 ° C. The humidity is preferably 50 to 100% rh, more preferably 70 to 100% rh, and still more preferably 80 to 100% rh. The traveling speed in the longitudinal direction is preferably 1 m / min or more, more preferably 3 m / min or more.
After stretching, the film is dried at 50 to 100 ° C., more preferably 60 to 90 ° C., for 0.5 to 10 minutes. More preferably, it is 1 to 5 minutes.
The absorption axis of the polarizing plate thus obtained is preferably 10 to 80 degrees, more preferably 30 to 60 degrees, and still more preferably 45 degrees (40 to 50 degrees).

(2-1-3) Bonding The saturated norbornene film after saponification and a polarizing layer prepared by stretching are bonded to prepare a polarizing plate. The laminating direction is preferably such that the casting axis direction of the saturated norbornene film and the stretching axis direction of the polarizing plate are 45 degrees.
The adhesive for bonding is not particularly limited, but examples thereof include PVA resins (including modified PVA such as acetoacetyl group, sulfonic acid group, carboxyl group, oxyalkylene group) and boron compound aqueous solution. preferable. The thickness of the adhesive layer is preferably 0.01 to 10 μm after drying, and particularly preferably 0.05 to 5 μm.
The polarizing plate thus obtained preferably has a higher light transmittance, and preferably has a higher degree of polarization. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and most preferably in the range of 40 to 50% in light having a wavelength of 550 nm. . The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% in light having a wavelength of 550 nm.
Furthermore, the polarizing plate thus obtained can be laminated with a λ / 4 plate to produce circularly polarized light. In this case, it is preferable to laminate so that the slow axis of λ / 4 and the absorption axis of the polarizing plate are 45 degrees. At this time, λ / 4 is not particularly limited, but more preferably has a wavelength dependency such that the Re or Rth value decreases as the wavelength decreases. Furthermore, it is preferable to use a polarizing plate having an absorption axis inclined by 20 ° to 70 ° with respect to the longitudinal direction and a λ / 4 plate made of an optically anisotropic layer made of a liquid crystalline compound.

(2-2) Application of optical compensation layer (creation of optical compensation sheet)
The optically anisotropic layer is for compensating the liquid crystal compound in the liquid crystal cell in the black display of the liquid crystal display device, and forms an alignment film on the saturated norbornene film of the present invention. It is formed by giving.
(2-2-1) Alignment film An alignment film is provided on the surface-treated saturated norbornene film. This film has a function of defining the alignment direction of liquid crystalline molecules. However, if the alignment state is fixed after aligning the liquid crystalline compound, the alignment film plays the role, and thus is not necessarily an essential component of the present invention. That is, it is possible to produce the polarizing plate of the present invention by transferring only the optically anisotropic layer on the alignment film in which the alignment state is fixed onto the polarizer.
The alignment film is an organic compound (eg, ω-tricosanoic acid) formed by rubbing treatment of an organic compound (preferably polymer), oblique deposition of an inorganic compound, formation of a layer having a microgroove, or Langmuir-Blodgett method (LB film). , Dioctadecylmethylammonium chloride, methyl stearylate). Furthermore, an alignment film in which an alignment function is generated by application of an electric field, application of a magnetic field or light irradiation is also known.
The alignment film is preferably formed by polymer rubbing treatment. In principle, the polymer used for the alignment film has a molecular structure having a function of aligning liquid crystal molecules.
In the present invention, in addition to the function of aligning liquid crystalline molecules, a cross-linking having a function of aligning a side chain having a crosslinkable functional group (eg, double bond) to the main chain or aligning liquid crystalline molecules. It is preferable to introduce a functional functional group into the side chain.

  As the polymer used for the alignment film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used, and a plurality of combinations thereof can be used. Examples of the polymer include methacrylate copolymers, styrene copolymers, polyolefins, polyvinyl alcohols, modified polyvinyl alcohols, poly (N--) described in paragraph No. [0022] of JP-A-8-338913, for example. Methylolacrylamide), polyester, polyimide, vinyl acetate copolymer, carboxymethylcellulose, polycarbonate and the like. Silane coupling agents can be used as the polymer. Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol and modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are most preferred. . It is particularly preferable to use two types of polyvinyl alcohol or modified polyvinyl alcohol having different degrees of polymerization. The saponification degree of polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%. It is preferable that the polymerization degree of polyvinyl alcohol is 100-5000.

A side chain having a function of aligning liquid crystal molecules generally has a hydrophobic group as a functional group. The specific type of functional group is determined according to the type of liquid crystal molecule and the required alignment state. For example, the modifying group of the modified polyvinyl alcohol can be introduced by copolymerization modification, chain transfer modification or block polymerization modification. Examples of modifying groups include hydrophilic groups (carboxylic acid groups, sulfonic acid groups, phosphonic acid groups, amino groups, ammonium groups, amide groups, thiol groups, etc.), hydrocarbon groups having 10 to 100 carbon atoms, fluorine atoms Examples include substituted hydrocarbon groups, thioether groups, polymerizable groups (unsaturated polymerizable groups, epoxy groups, azirinidyl groups, etc.), alkoxysilyl groups (trialkoxy groups, dialkoxy groups, monoalkoxy groups), and the like. As specific examples of these modified polyvinyl alcohol compounds, for example, paragraph numbers [0022] to [0145] in JP-A No. 2000-155216 and paragraph numbers [0018] to [0018] in JP-A No. 2002-62426 are described. [0022] and the like.
When a side chain having a crosslinkable functional group is bonded to the main chain of the alignment film polymer, or a crosslinkable functional group is introduced into a side chain having a function of aligning liquid crystalline molecules, the alignment film polymer and the optically anisotropic film The polyfunctional monomer contained in the conductive layer can be copolymerized. As a result, not only between the polyfunctional monomer and the polyfunctional monomer, but also between the alignment film polymer and the alignment film polymer and between the polyfunctional monomer and the alignment film polymer is firmly bonded by a covalent bond. Therefore, the strength of the optical compensation sheet can be remarkably improved by introducing the crosslinkable functional group into the alignment film polymer.

The crosslinkable functional group of the alignment film polymer preferably contains a polymerizable group in the same manner as the polyfunctional monomer. Specific examples include those described in paragraphs [0080] to [0100] in JP-A-2000-155216. Apart from the crosslinkable functional group, the alignment film polymer can also be crosslinked using a crosslinking agent.
Examples of the crosslinking agent include aldehydes, N-methylol compounds, dioxane derivatives, compounds that act by activating carboxyl groups, active vinyl compounds, active halogen compounds, isoxazole, and dialdehyde starch. Two or more kinds of crosslinking agents may be used in combination. Specific examples include compounds described in paragraphs [0023] to [0024] in JP-A-2002-62426. Aldehydes having high reaction activity, particularly glutaraldehyde are preferred.
0.1-20 mass% is preferable with respect to a polymer, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable. The amount of the unreacted crosslinking agent remaining in the alignment film is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less. By adjusting in this way, even if the alignment film is used for a long time in a liquid crystal display device or left in a high temperature and high humidity atmosphere for a long time, sufficient durability without reticulation can be obtained. May occur.
The alignment film can be basically formed by applying the polymer on the transparent support containing the alignment film forming material and the crosslinking agent, followed by drying by heating (crosslinking) and rubbing treatment. As described above, the crosslinking reaction may be carried out at any time after coating on the transparent support. When a water-soluble polymer such as polyvinyl alcohol is used as the alignment film forming material, the coating solution is preferably a mixed solvent of an organic solvent (eg, methanol) having a defoaming action and water. The ratio of water: methanol is preferably 0: 100 to 99: 1, and more preferably 0: 100 to 91: 9. Thereby, generation | occurrence | production of a bubble is suppressed and the defect of the layer surface of an alignment film and also an optically anisotropic layer reduces remarkably.

The alignment film is preferably applied by spin coating, dip coating, curtain coating, extrusion coating, rod coating, or roll coating. A rod coating method is particularly preferable. The film thickness after drying is preferably 0.1 to 10 μm. Heating and drying can be performed at 20 ° C to 110 ° C. In order to form sufficient cross-linking, 60 ° C to 100 ° C is preferable, and 80 ° C to 100 ° C is particularly preferable. The drying time can be 1 minute to 36 hours, preferably 1 minute to 30 minutes. The pH is preferably set to an optimum value for the crosslinking agent to be used. When glutaraldehyde is used, the pH is 4.5 to 5.5, and 5 is particularly preferable.
The alignment film is provided on the saturated norbornene film or an undercoat layer provided thereon. The alignment film can be obtained by rubbing the surface after crosslinking the polymer layer as described above.
For the rubbing treatment, a treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, a method of obtaining the orientation by rubbing the surface of the orientation film in a certain direction using paper, gauze, felt, rubber, nylon, polyester fiber or the like can be used. Generally, it is carried out by rubbing several times using a cloth or the like in which fibers having a uniform length and thickness are planted on average.
When industrially implemented, this is achieved by bringing a rotating rubbing roll into contact with the film provided with the polarizing layer being transported, but the roundness, cylindricity, and deflection (eccentricity) of the rubbing roll are Any of them is preferably 30 μm or less. The film wrap angle on the rubbing roll is preferably 0.1 to 90 °. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 ° or more. As for the conveyance speed of a film, 1-100 m / min is preferable. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 °. When used for a liquid crystal display device, 40 to 50 ° is preferable. 45 ° is particularly preferred.
The thickness of the alignment film thus obtained is preferably in the range of 0.1 to 10 μm.

Next, the liquid crystalline molecules of the optically anisotropic layer are aligned on the alignment film. Thereafter, as necessary, the alignment film polymer and the polyfunctional monomer contained in the optically anisotropic layer are reacted, or the alignment film polymer is crosslinked using a crosslinking agent.
The liquid crystalline molecules used in the optically anisotropic layer include rod-like liquid crystalline molecules and discotic liquid crystalline molecules. The rod-like liquid crystal molecules and the disk-like liquid crystal molecules may be high-molecular liquid crystals or low-molecular liquid crystals, and further include those in which low-molecular liquid crystals are cross-linked and no longer exhibit liquid crystallinity.

(2-2-2) Rod-like liquid crystalline molecules As rod-like liquid crystalline molecules, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, Cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.
The rod-like liquid crystalline molecule includes a metal complex. In addition, a liquid crystal polymer containing a rod-like liquid crystalline molecule in a repeating unit can also be used as the rod-like liquid crystalline molecule. In other words, the rod-like liquid crystal molecule may be bonded to a (liquid crystal) polymer.
For rod-like liquid crystalline molecules, see Chapter 4, Chapter 7 and Chapter 11 of the Chemistry of the Quarterly Chemistry Vol. 22 (1994) The Chemical Society of Japan, and the 142th Committee of the Japan Society for the Promotion of Science. Described in Chapter 3.
The birefringence of the rod-like liquid crystal molecule is preferably in the range of 0.001 to 0.7.
The rod-like liquid crystalline molecule preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably a radically polymerizable unsaturated group or a cationically polymerizable group. Specifically, for example, polymerization described in paragraphs [0064] to [0086] of JP-A-2002-62427 is described. And a polymerizable liquid crystal compound.

(2-2-3) Discotic liquid crystalline molecules The discotic liquid crystalline molecules include C.I. Destrade et al., Mol. Cryst. 71, 111 (1981), benzene derivatives described in C.I. Destrade et al., Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990); Kohne et al., Angew. Chem. 96, page 70 (1984) and the cyclohexane derivatives described in J. Am. M.M. Lehn et al. Chem. Commun. , 1794 (1985), J. Am. Zhang et al., J. Am. Chem. Soc. 116, 2655 (1994), azacrown type and phenylacetylene type macrocycles are included.
As a discotic liquid crystalline molecule, a compound having liquid crystallinity having a structure in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule Is also included. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. In the optically anisotropic layer formed from the discotic liquid crystalline molecules, the compound finally contained in the optically anisotropic layer does not need to be a discotic liquid crystalline molecule. Also included are compounds having a group that reacts with heat or light and, as a result, polymerized or cross-linked by reaction with heat or light, resulting in a high molecular weight and loss of liquid crystallinity. Preferred examples of the discotic liquid crystalline molecules are described in JP-A-8-50206. The polymerization of discotic liquid crystalline molecules is described in JP-A-8-27284.
In order to fix the discotic liquid crystalline molecules by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline molecules. A compound in which the discotic core and the polymerizable group are bonded via a linking group is preferable, whereby the orientation state can be maintained even in the polymerization reaction. Examples thereof include compounds described in paragraph numbers [0151] to [0168] in JP-A No. 2000-155216.

In hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystalline molecule and the plane of the polarizing plate increases or decreases in the depth direction of the optically anisotropic layer and with increasing distance from the plane of the polarizing layer. is doing. The angle preferably decreases with increasing distance. Further, the change in angle can be a continuous increase, a continuous decrease, an intermittent increase, an intermittent decrease, a change including a continuous increase and a continuous decrease, or an intermittent change including an increase and a decrease. The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if the angle includes a region where the angle does not change, the angle only needs to increase or decrease as a whole. Furthermore, it is preferable that the angle changes continuously.
The average direction of the major axis of the discotic liquid crystalline molecules on the polarizing plate side can be generally adjusted by selecting a discotic liquid crystalline molecule or an alignment film material, or by selecting a rubbing treatment method. In addition, the major axis (disk surface) direction of the surface-side (air-side) discotic liquid crystalline molecules is generally adjusted by selecting the type of additive used together with the discotic liquid crystalline molecules or discotic liquid crystalline molecules. be able to. Examples of the additive used together with the discotic liquid crystalline molecule include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the orientation direction of the major axis can also be adjusted by selecting liquid crystalline molecules and additives as described above.

(2-2-4) Other composition of optically anisotropic layer Along with the above liquid crystalline molecules, a plasticizer, a surfactant, a polymerizable monomer, etc. are used in combination, and the uniformity of the coating film, the strength of the film The orientation of liquid crystal molecules can be improved. It is preferable that the compound has compatibility with the liquid crystal molecules and can change the tilt angle of the liquid crystal molecules or does not inhibit the alignment.
Examples of the polymerizable monomer include radically polymerizable or cationically polymerizable compounds. Preferably, it is a polyfunctional radically polymerizable monomer and is preferably copolymerizable with the above-described polymerizable group-containing liquid crystal compound. Examples thereof include those described in paragraph numbers [0018] to [0020] in JP-A No. 2002-296423. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline molecules.
Examples of the surfactant include conventionally known compounds, and fluorine compounds are particularly preferable. Specific examples include compounds described in paragraph numbers [0028] to [0056] in JP-A-2001-330725.
The polymer used together with the discotic liquid crystalline molecule is preferably capable of changing the tilt angle of the discotic liquid crystalline molecule.
A cellulose ester can be mentioned as an example of a polymer. Preferable examples of the cellulose ester include those described in paragraph [0178] of JP-A No. 2000-155216. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass, and in the range of 0.1 to 8% by mass with respect to the liquid crystal molecule so as not to inhibit the alignment of the liquid crystal molecules. It is more preferable.
The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline molecules is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

(2-2-5) Formation of Optically Anisotropic Layer The optically anisotropic layer is formed by applying a coating liquid containing liquid crystalline molecules and, if necessary, a polymerizable initiator and an optional component described later on the alignment film. It can be formed by coating.
As a solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.
The coating liquid can be applied by a known method (eg, wire bar coating method, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).
The thickness of the optically anisotropic layer is preferably 0.1 to 20 μm, more preferably 0.5 to 15 μm, and most preferably 1 to 10 μm.

(2-2-6) Fixing of alignment state of liquid crystalline molecules The aligned liquid crystalline molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.
Examples of the photopolymerization initiator include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ether (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin. Compound (described in US Pat. No. 2,722,512), polynuclear quinone compound (described in US Pat. Nos. 3,046,127 and 2,951,758), a combination of triarylimidazole dimer and p-aminophenyl ketone (US Pat. No. 3,549,367) Acridine and phenazine compounds (JP-A-60-105667, U.S. Pat. No. 4,239,850) and oxadiazole compounds (U.S. Pat. No. 4,212,970).
The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.
It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules.
The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of 20~5000mJ / cm ^2, more preferably in the range of 100 to 800 mJ / cm ² . In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.
Furthermore, you may provide a protective layer on an optically anisotropic layer as needed.

It is also preferable to combine this optical compensation film and a polarizing layer. Specifically, the optically anisotropic layer is formed by applying the coating liquid for the optically anisotropic layer as described above to the surface of the polarizing plate. As a result, without using a polymer film between the polarizing plate and the optically anisotropic layer, a thin polarizing plate having a small stress (strain × cross-sectional area × elastic modulus) associated with the dimensional change of the polarizing plate can be produced. When the polarizing plate according to the present invention is attached to a large liquid crystal display device, an image with high display quality can be displayed without causing problems such as light leakage.
The inclination angle of the polarizing layer and the optical compensation layer may be stretched so as to match the angle formed between the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell. preferable. A normal inclination angle is 45 °. Recently, however, devices that are not necessarily 45 ° have been developed for transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted in accordance with the design of the LCD.
(2-2-7) Liquid Crystal Display Device Each liquid crystal mode in which such an optical compensation film is used will be described.
(TN mode liquid crystal display)
It is most frequently used as a color TFT liquid crystal display device and is described in many documents. The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which the rod-like liquid crystalline molecules rise at the center of the cell and the rod-like liquid crystalline molecules lie in the vicinity of the cell substrate.
(OCB mode liquid crystal display)
This is a bend alignment mode liquid crystal cell in which rod-like liquid crystal molecules are aligned in a substantially opposite direction (symmetrically) between the upper part and the lower part of the liquid crystal cell. Liquid crystal display devices using a bend alignment mode liquid crystal cell are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal molecules are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is also called an OCB (Optically Compensatory Bend) liquid crystal mode.
Similarly to the TN mode, the liquid crystal cell in the OCB mode is in a black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystal molecules rise in the center of the cell and the rod-like liquid crystal molecules lie in the vicinity of the cell substrate. .
(VA mode liquid crystal display device)
The feature is that the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In the VA mode liquid crystal cell, (1) the rod-like liquid crystalline molecules are oriented substantially vertically when no voltage is applied. In addition to a narrowly defined VA mode liquid crystal cell (described in JP-A-2-176625) that is aligned substantially horizontally when a voltage is applied, (2) the VA mode is multi-domained to expand the viewing angle ( Liquid crystal cell (in MVA mode) (SID97, Digest of tech. Papers 28 (1997) 845), (3) Rod-like liquid crystal molecules are substantially vertically aligned when no voltage is applied, and twisted A liquid crystal cell in a domain alignment mode (n-ASM mode) (described in the proceedings 58-59 (1998) of the Japanese Liquid Crystal Society) and (4) a SURVAVAL mode liquid crystal cell (LCD interface) Announced at National 98).
(Other liquid crystal display devices)
The ECB mode and STN mode liquid crystal display devices can be optically compensated in the same way as described above.

(2-3) Application of antireflection layer (antireflection film)
In general, the antireflection film includes a low refractive index layer which is also an antifouling layer, and at least one layer having a higher refractive index than that of the low refractive index layer (ie, a high refractive index layer and a medium refractive index layer). On a substrate which is a saturated norbornene film.
Colloidal metal by multilayer deposition of transparent thin films of inorganic compounds (metal oxides, etc.) with different refractive indexes by chemical vapor deposition (CVD) method, physical vapor deposition (PVD) method, sol-gel method of metal compounds such as metal alkoxides Examples include a method of forming a thin film by post-processing (ultraviolet irradiation: JP-A-9-157855, plasma processing: JP-A-2002-327310) after forming an oxide particle film.
On the other hand, various antireflection films formed by laminating thin films in which inorganic particles are dispersed in a matrix have been proposed as antireflection films with high productivity.
The antireflection film which consists of the antireflection layer which provided the anti-glare property which the antireflection film by application | coating as mentioned above provided the surface of the uppermost layer with the shape of a fine unevenness | corrugation is also mentioned.
The saturated norbornene film of the present invention can be applied to any of the above methods, but the coating method (coating type) is particularly preferable.

(2-3-1) Layer structure of coating type antireflection film An antireflection film having a layer structure in the order of at least a medium refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) on a substrate is as follows. It is designed to have a refractive index that satisfies the following relationship.
Refractive index of high refractive index layer> refractive index of medium refractive index layer> refractive index of transparent support> refractive index of low refractive index layer Also, a hard coat layer is provided between the transparent support and the intermediate refractive index layer. Also good. Furthermore, it may consist of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.
Examples thereof include JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like. Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (eg, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.
The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. The strength of the film is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400.

(2-3-2) High Refractive Index Layer and Medium Refractive Index Layer A layer having a high refractive index of the antireflection film is a cured product containing at least high-refractive index inorganic compound ultrafine particles having an average particle size of 100 nm or less and a matrix binder. It consists of a sex membrane.
Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.
In order to obtain such ultrafine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agents, etc .: JP-A Nos. 1-295503, 11-153703, 2000-9908). , Anionic compounds or organometallic coupling agents: JP 2001-310432 A, etc., core-shell structure with high refractive index particles as the core (JP 2001-166104 A, etc.), specific dispersant combined use (E.g., Japanese Patent Laid-Open No. 11-153703, Japanese Patent No. US6210858B1, Japanese Patent Laid-Open No. 2002-27776069, etc.).
Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.
Furthermore, it is selected from a polyfunctional compound-containing composition containing at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound containing a hydrolyzable group, and a partial condensate composition thereof. At least one composition is preferred. Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.
A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. For example, it describes in Unexamined-Japanese-Patent No. 2001-293818.
The refractive index of the high refractive index layer is generally 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.
The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

(2-3-3) Low Refractive Index Layer The low refractive index layer is formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is 1.20 to 1.55, preferably 1.30 to 1.50.
It is preferable to construct as the outermost layer having scratch resistance and antifouling property. As means for greatly improving the scratch resistance, it is effective to impart slipperiness to the surface, and conventionally known thin film layer means such as introduction of silicone or introduction of fluorine can be applied.
The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50, more preferably 1.36 to 1.47. The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing fluorine atoms in the range of 35 to 80% by mass.
For example, paragraph numbers [0018] to [0026] of Japanese Patent Application Laid-Open No. 9-222503, paragraph numbers [0019] to [0030] of Japanese Patent Application Laid-Open No. 11-38202, and paragraph numbers of Japanese Patent Application Laid-Open No. 2001-40284. [0027] to [0028], JP-A 2000-284102, and the like.
The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone (eg, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) and the like can be mentioned.
The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is carried out at the same time or after the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer, etc. It is preferable to carry out by light irradiation or heating.
Also preferred is a sol-gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst.
For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.
The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. Low refractive index inorganic compounds, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820, etc.), silane coupling agents, slip agents, surfactants, and the like can be contained.
When the low refractive index layer is positioned below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.
The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

(2-3-4) Hard coat layer The hard coat layer is provided on the surface of the substrate in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the transparent support and the high refractive index layer.
The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound. The curable functional group is preferably a photopolymerizable functional group, and the hydrolyzable functional group-containing organometallic compound is preferably an organic alkoxysilyl compound.
Specific examples of these compounds are the same as those exemplified for the high refractive index layer.
Specific examples of the constituent composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO 0/46617.
The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.
The hard coat layer can also serve as an antiglare layer (described later) provided with particles having an average particle size of 0.2 to 10 μm to provide an antiglare function (antiglare function).
The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.
The strength of the hard coat layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

(2-3-5) Forward scattering layer The forward scattering layer is provided in order to give a viewing angle improvement effect when the viewing angle is inclined in the vertical and horizontal directions when applied to a liquid crystal display device. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function.
For example, Japanese Patent Application Laid-Open No. 11-38208 specifying a forward scattering coefficient, Japanese Patent Application Laid-Open No. 2000-199809 having a relative refractive index of a transparent resin and fine particles in a specific range, and Japanese Patent Application Laid-Open No. 2002 specifying a haze value of 40% or more. -107512 gazette etc. are mentioned.
(2-3-6) Other layers In addition to the above layers, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.
(2-3-7) Coating method Each layer of the antireflection film is formed by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating, a micro gravure method or an extrusion coating method ( U.S. Pat. No. 2,681,294) can be formed by coating.

(2-3-8) Antiglare Function The antireflection film may have an antiglare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.
As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently maintained. For example, a method of forming irregularities on the film surface using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower layer of the low refractive index layer (high refractive index layer, medium refractive index layer) Alternatively, a small amount (0.1 to 50% by mass) of relatively large particles (particle size 0.05 to 2 μm) is added to the hard coat layer to form a surface uneven film, and these shapes are maintained thereon. A method of providing a low refractive index layer (for example, JP 2000-281410 A, JP 2000-95893 A, JP 2001-100004 A, 2001-281407, etc.), an uppermost layer (antifouling layer) A method of physically transferring an uneven shape onto the surface after coating (for example, as an embossing method, JP-A-63-278839, JP-A-11-183710, JP-A-2000-275401) Wherein) and the like.

  The present invention will be described more specifically with reference to the following examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention is not limited to the specific examples shown below.

1. Saturated norbornene resin (1) Saturated norborn resin-A
6-methyl-1,4,5,8-dimethano-1,4,4a, 5,6,7,8,8a-octahydronaphthalene, 10 parts by weight of a 15% cyclohexane solution of triethylaluminum as a polymerization catalyst, triethylamine 5 parts by weight and 10 parts by weight of a 20% cyclohexane solution of titanium tetrachloride were added to carry out ring-opening polymerization in cyclohexane, and the resulting ring-opening polymer was hydrogenated with a nickel catalyst to obtain a polymer solution. This polymer solution was coagulated in isopropyl alcohol and dried to obtain a powdery resin. The number average molecular weight of this resin was 40,000, the hydrogenation rate was 99.8% or more, and the Tg was 139 ° C.
(2) Saturated norvol resin-B
100 parts by weight of 8-methyl-8-methoxycarbonyltetracyclo [4.4.0.12.5, 17.10] -3-dodecene (specific monomer B) and 5- (4-biphenylcarbonyloxy) A reaction vessel in which 150 parts by weight of bicyclo [2.2.1] hept-2-ene (specific monomer A), 18 parts by weight of 1-hexene (molecular weight regulator) and 750 parts of toluene were replaced with nitrogen was charged. The solution was heated to 60 ° C. Next, 0.62 parts by weight of a toluene solution of triethylaluminum (1.5 mol / L) as a polymerization catalyst and tungsten hexachloride modified with t-butanol and methanol (t-butanol: methanol: 3.7 parts of a toluene solution (concentration 0.05 mol / L) of tungsten = 0.35 mol: 0.3 mol: 1 mol) was added, and the system was opened by heating and stirring at 80 ° C. for 3 hours. A ring-opening polymer solution was obtained by a ring polymerization reaction. The polymerization conversion rate in this polymerization reaction was 97%, and the intrinsic viscosity (ηinh) of the obtained ring-opened polymer measured in chloroform at 30 ° C. was 0.65 dL / g.
The autoclave was charged with 4,000 parts of the ring-opening polymer solution thus obtained, and 0.48 parts by weight of RuHCl (CO) [P (C ₆ H ₅ ) ₃ ] ₃ was added to the ring-opening polymer solution. The hydrogenation reaction was performed by heating and stirring for 3 hours under the conditions of hydrogen gas pressure of 100 kg / cm ² and reaction temperature of 165 ° C. After cooling the obtained reaction solution (hydrogenated polymer solution), the hydrogen gas was released. This reaction solution was poured into a large amount of methanol to separate and recover a coagulated product, which was dried to obtain a hydrogenated polymer (specific cyclic polyolefin resin). The hydrogenated polymer thus obtained was measured for the hydrogenation rate of olefinically unsaturated bonds using 400 MHz, 1H-NMR, and found to be 99.9%. The Tg was 110 ° C., and when the number average molecular weight (Mn) and weight average molecular weight (Mw) in terms of polystyrene were measured by the GPC method (solvent: tetrahydrofuran), the number average molecular weight (Mn) was 39,000 and the weight average The molecular weight (Mw) was 126,000, and the molecular weight distribution (Mw / Mn) was 3.23.

2. Film Formation (1) Melt Film Formation The saturated norbornene resin-A was formed into a cylindrical pellet having a diameter of 3 mm and a length of 5 mm. This was dried with a vacuum dryer at 110 ° C., the water content was adjusted to 0.1% or less, and then charged into a hopper adjusted to (Tg−10) ° C.
After adjusting the melting temperature so that the melt viscosity becomes 5000 Pa · s and melting using a uniaxial kneader at this temperature for 5 minutes, from a T-die set higher by 10 ° C. than the melting temperature (Tg-5) It was cast on a casting drum set at 0 ° C. and solidified into a film. At this time, each level electrostatic application method (a 10 kV wire was placed 10 cm from the point where the melt was attached to the casting drum) was used. The solidified melt was peeled off and wound up. In addition, after trimming both ends (each 3% of the total width) just before winding, the both ends were subjected to thicknessing (knurling) with a width of 10 mm and a height of 50 μm. In each level, the width was 1.5 m, and 3000 m was wound at 30 m / min.

(2) Solution casting The saturated norbornene resin-B was added to toluene with stirring so as to have a concentration of 30%. When the addition was completed, stirring was stopped and the slurry was swelled at 25 ° C. for 3 hours to prepare a slurry. This was stirred again and completely dissolved (hereinafter, this solution is referred to as a dope). The viscosity of this solution at room temperature was 30,000 mPa · s). This was filtered with a filter paper having an absolute filtration accuracy of 0.01 mm (manufactured by Toyo Filter Paper Co., Ltd., # 63), and further filtered with a filter paper having an absolute filtration accuracy of 2.5 μm (manufactured by Pall, FH025).
The above-mentioned dope was heated to 35 ° C. and cast on a mirror surface stainless steel support having a band length of 60 m set at 25 ° C. The Gieseer used was similar to that described in Japanese Patent Application Laid-Open No. 11-314233. The casting speed was 60 m / min and the casting width was 250 cm.
The residual solvent was peeled off at 100% by mass, dried at 130 ° C., and then wound up when the residual solvent shown in Table 2 was obtained to obtain a saturated norbornene film. The obtained film was trimmed at both ends by 3 cm, and then a knurling having a height of 100 μm was imparted to a portion 2 to 10 mm from both ends, and wound into a 3000 m roll.

3. Stretching The saturated norbornene film obtained by the melt casting was stretched under the conditions described in Table 1, and the saturated norbornene film obtained by solution casting was stretched under the conditions described in Table 2. In addition, the stretching temperature for each level is shown as “vs. Tg” in Table 1 at a temperature of + and −, respectively, indicating how much higher or lower the Tg of each level of resin is.
The evaluation results of the stretched film thus obtained are shown in Tables 1 and 2. Longitudinal stretching was carried out by changing the conveying speed of the nip roll. Further, Table 1 and Table 2 show that “inside” indicates that the nip roll used for stretching was installed in the stretching zone, and “outside” indicates that it was installed outside the stretching zone. Transverse stretching was performed at a temperature of Tg + 10 ° C. using a tenter.

The measurement method used in the present invention is described below.
(1) Adhesion trace A sample film is placed on a black flat cloth and visually observed with reflected light under a tungsten lamp. A pattern of “C” shape (a bird's foot shape) of about several millimeters confirmed on the surface is observed for 20 m ² , and the number thereof is counted and expressed as an average value per 1 m ² . ("C" -shaped adhesion marks are generated when the film comes into contact with the stretching roll, and when the film leaves the film, the adhesive point is the starting point and the film surface is peeled off radially)
(2) Re value, Rth value, width direction, Re value in the longitudinal direction, Rth value fluctuation (2-1) Sampling in the MD direction 100 points at 0.5 m intervals in the longitudinal direction are cut out to a size of 1 cm ² .
(2-2) Sampling in the TD direction 50 points are cut into a size of 1 cm ² at equal intervals over the entire width of film formation.
(2-3) Re value and Rth value measurement After adjusting the above sample film to 25 ° C. and 60% rh for 3 hours or more, using an automatic birefringence meter (KOBRA-21ADH / PR: manufactured by Oji Scientific Instruments) At 25 ° C. and 60% rh, the retardation value (Rth value) at a wavelength of 550 nm was measured from the direction perpendicular to the sample film surface and ± 40 ° from the normal to the film surface. It was calculated from the measured values in the in-plane retardation (Re value), the vertical direction, and the ± 40 ° direction from the vertical direction. The total average of the sampling points was defined as Re value and Rth value.
(2-4) Re value and Rth value fluctuation The difference between the maximum value and the minimum value of the MD direction 100 points and the TD direction 50 points is divided by the average value, and the percentage value is shown as the Re value, The Rth value was changed.
(3) Aspect ratio A value (L / W) obtained by dividing the distance between nip rolls used for stretching (L: distance between the cores of two pairs of nip rolls) by the width (W) of the saturated norbornene film before stretching. When there were three or more pairs of nip rolls, the largest L / W value was taken as the aspect ratio.
The Re value, Rth value (average value) of these stretched films obtained in this way and the rate of variation thereof were measured by the above methods and are shown in Tables 1 and 2. In addition, the adhesion unevenness was also measured by the above method and displayed in Tables 1 and 2.
(4) Tg measurement method Tg was measured by the following method. In addition, what added a plasticizer measured after adding a plasticizer. The results are shown in Tables 1 and 2.
20 mg of a sample was placed in a DSC measurement pan. This was heated from 30 ° C. to 250 ° C. at 10 ° C./min in a nitrogen stream (1st-run), and then cooled to 30 ° C. at −10 ° C./min. Thereafter, the temperature was raised again to 30 to 250 ° C. (2nd-run). The temperature at which the baseline starts to deviate from the low temperature side in 2nd-run is shown in Tables 1 and 2 as Tg. Moreover, 0.05 mass% of silicon dioxide part particles (Aerosil R972V) were added to all levels.

3. Preparation of polarizing plate (1) Surface treatment In any level, the film surface was subjected to corona treatment so that the contact angle with water on the surface was 60 degrees.
(2) Creation of Polarizing Layer A polarizing layer having a thickness of 20 μm was prepared by the oblique stretching method or the parallel stretching method shown below. In the present invention, a film that has been stretched and imparted polarizing ability is called a polarizing layer, and a film sandwiched between at least two protective films or retardation films is called a polarizing plate.
(2-1) Diagonal Stretching Method According to Example 1 of Japanese Patent Application Laid-Open No. 2002-86554, stretching was performed using a tenter so that the stretching axis was 45 degrees obliquely.
(2-2) Parallel Stretching Method According to Example 1 of Japanese Patent Laid-Open No. 2001-141926, a circumferential speed difference was given between two pairs of nip rolls to stretch in the longitudinal direction.
(3) Bonding The polarizing layer obtained in this manner was sandwiched between the saponified stretched saturated norbornene film (retardation plate) and the saponified polarizing plate protective film (trade name: Fujitac). At this time, the retardation plate and the polarizing layer were bonded together using an epoxy adhesive. The above PVA aqueous solution was bonded as an adhesive between Fujitac and the polarizing layer. The laminating direction was such that the longitudinal direction of the polarization axis and the retardation plate was 45 degrees. The polarizing plate thus obtained has a retardation plate on the liquid crystal side and a Fujitack on the outside (viewing side), and the 20-inch VA liquid crystal described in FIGS. 2 to 9 of JP-A-2000-154261. Tables 1 and 2 show the frequency of occurrence of display unevenness per unit area after being mounted on a display device liquid crystal display device and visually evaluated. Good performance was obtained with the present invention.

4). Preparation of optical compensation film When the stretched norbornene film of the present invention was used in place of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-11-316378, as shown in Table 2 (optical compensation) A good optical compensation film was prepared.
In place of the cellulose acetate film coated with the liquid crystal layer of Example 1 of JP-A-7-333433, an optical compensation filter film was produced by changing to the stretched saturated norbornene film of the present invention (described as optical compensation film B). A good optical compensation film could be produced.
On the other hand, those outside the scope of the present invention have deteriorated optical characteristics. In particular, the reduction according to Example 1 of JP-A-2001-42130 (Comparative Example 1-4 in Table 1) was particularly remarkable.

5. Production of Low Reflective Film A stretched norbornene film of the present invention was produced by using the stretched saturated norbornene film of the present invention in accordance with Example 47 of the Japan Institute of Invention and Technology (Publication No. 2001-1745). Optical performance was obtained.

6). Preparation of liquid crystal display element The polarizing plate of the present invention is applied to the liquid crystal display device described in Example 1 of JP-A-10-48420 and the discotic liquid crystal molecule described in Example 1 of JP-A-9-26572. Including an optically anisotropic layer, an alignment film coated with polyvinyl alcohol, a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261, and FIGS. 10 to 10 of JP-A-2000-154261. 15 in the 20-inch OCB type liquid crystal display device. Furthermore, when the low reflection film of the present invention was applied to the outermost layer of these liquid crystal display devices and evaluated, as shown in Tables 1 and 2, a good liquid crystal display element free from display unevenness due to adhesion marks was obtained. It was.

1 Entrance side nip roll 2 Stretch zone 3 Exit side nip roll 4 Saturated norbornene resin (film)
5 Nip rolls installed in the drying zone

Claims (1)

A method for producing a saturated norbornene film comprising a step of longitudinally stretching 1.1 to 2.5 times in a saturated norbornene resin having an aspect ratio of 3.

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