JPH0875921A - Phase difference film - Google Patents

Abstract

PURPOSE: To obtain a phase difference film exhibiting excellent phase difference property, high in transparency and excellent in properties such as humidity resistance, dimensional stability, solvent resistance, thermal stability and light stability by controlling retardation value to a specific range, phase ununiformity to equal to or below a specific value and forming out of a cyclic olefin random copolymer uniaxially stretched film. CONSTITUTION: This phase difference film is formed out of the uniaxially stretched film composed of the random copolymer of a cyclic olefin expressed by formula I or II and ethylene, and is controlled to 200-800nm in retardation value and <=15nm in phase ununiformity. In the formula I, n is 0 or 1, m is 0 or positive integers, q is 0 or 1, each of R<1> -R<18> , R<a> and R<b> is independently hydrogen atom, a halogen atom or a hydrocarbon group. In the formula II, each of p and q is 0 or integers of >=1, each of m and n is 0, 1 or 2, each of R<1> -R<19> is independently hydrogen atom, a halogen atom, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, an aromatic hydrocarbon group or an alkoxyl group.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a retardation film made of a cyclic olefin random copolymer.

[0002]

2. Description of the Related Art In recent years, liquid crystal displays have been widely used as display devices for computers or word processors, display devices for small televisions and the like. In particular, since the STN liquid crystal display system has been put to practical use, white STN display devices and color STN display devices have received attention. Such a liquid crystal display as it is is colored blue or yellow depending on the relationship between the birefringence of the liquid crystal display and visible light. In a liquid crystal display such as a white STN display device and a color STN display device, the coloring due to the retardation of cells of such a liquid crystal display is offset by attaching a retardation film having a specific retardation value to the substrate surface of the liquid crystal cell. are doing.

Such a retardation film is required to have high transparency, have a retardation value within a certain range, and have little phase unevenness. Conventionally, as a resin for forming such a retardation film,
Resins such as polycarbonate or polyvinyl alcohol are used. Both the polycarbonate film and the polyvinyl alcohol film have high transparency and are suitable as a retardation film, but when the two are compared, polycarbonate is particularly suitable as a retardation film forming material.

Regarding the retardation film using such a polycarbonate, for example, Japanese Patent Application Laid-Open No. 2-89006 discloses an invention of a method for producing a retardation film using a polycarbonate.

However, the retardation film made of this polycarbonate has room for improvement in terms of moisture resistance, dimensional stability when absorbing water, and solvent resistance. That is, the retardation film is often used by laminating it with a polarizing film or the like, and the polycarbonate retardation film may be attacked by the solvent contained in the adhesive used in the pasting process. The appearance of a retardation film having a high solvent property is desired. In addition, recently, the use of liquid crystal displays has expanded dramatically, and the use conditions of the liquid crystal displays have become increasingly severe with the expansion of the uses of such liquid crystal displays. Since it is often used under wet conditions, the emergence of a retardation film having excellent dimensional stability even under such severe conditions is desired.

As a retardation film (plate) that solves the problems of the conventional retardation film made of polycarbonate or the like, in JP-A-4-245202, a cyclic olefin polymer is stretched uniaxially. The invention of a retardation film comprising a film or sheet is disclosed.

The term "cyclic olefin polymer" as used herein means that a polymer having an unsaturated bond obtained by ring-opening polymerization of norbornene derived from cyclopentadiene is subjected to hydrogenation as shown by the following formula. It is described as the obtained polyolefin.

[0008]

[Chemical 3]

(In the above formula, R ₁ and R ₂ are hydrocarbon groups.) That is, the cyclic olefin polymer used here is a hydrogenated product of a cyclic olefin ring-opening polymer.

However, the hydrogenated product of such a cyclic olefin ring-opening polymer does not have a high moisture vapor transmission rate, so that the moisture resistance of the film is not so high. Further, it is not easy to completely hydrogenate the cyclic olefin ring-opening polymer, and therefore a double bond may remain in the hydrogenated product of the cyclic olefin ring-opening polymer.
The hydrogenated product in which the double bond remains has a problem that it has poor heat resistance stability and light stability because the remaining double bond is active.

[0011]

An object of the present invention is to provide a phase difference which exhibits good retardation properties, is highly transparent, and is excellent in properties such as humidity resistance, dimensional stability, solvent resistance, heat stability and light resistance. The purpose is to provide a film.

[0012]

The retardation film of the present invention is formed from a uniaxially stretched film composed of a random copolymer of a cyclic olefin represented by the following formula [I] or [II] and ethylene, and has a retardation value of It is characterized by being in the range of 200 to 800 nm and having a phase unevenness of 15 nm or less.

[0013]

[Chemical 4] ... [I]

In the above formula [I], n is 0 or 1,
m is 0 or a positive integer, q is 0 or 1,
R ^{1 to} R ¹⁸ and R ^a and R ^b are each independently a hydrogen atom, a halogen atom or a hydrocarbon group,
R ^{15 to} R ¹⁸ may be bonded to each other to form a monocycle or polycycle, and the monocycle or polycycle may have a double bond, and R ¹⁵ and R ¹⁶ are Or R ¹⁷ and R ¹⁸
And may form an alkylidene group.

[0015]

[Chemical 5] ... [II]

In the above formula [II], p and q are 0 or 1.
The above integers, m and n are 0, 1 or 2, and R ^{1 to} R ¹⁹ are each independently a hydrogen atom, a halogen atom, an aliphatic hydrocarbon group, an alicyclic hydrocarbon group, or an aromatic group. A hydrocarbon group or an alkoxy group, R ⁹ or R ¹⁰
The carbon atom to which R is bonded and the carbon atom to which R ¹³ is bonded or the carbon atom to which R ¹¹ is bonded may be bonded directly or through an alkylene group having 1 to 3 carbon atoms. Of course, when n = m = 0, R ¹⁵ and R ¹² or R ¹⁵ and R ¹⁹ may combine with each other to form a monocyclic or polycyclic aromatic ring.

Since the retardation film of the present invention is formed from a cyclic olefin random copolymer in which the above-mentioned specific cyclic olefin and ethylene are randomly copolymerized, it has high transparency, moisture resistance and size. It has excellent properties such as stability, solvent resistance, heat resistance stability, and light resistance stability, and has a property that the retardation value is within a specific range and there is little phase unevenness.

[0018]

DETAILED DESCRIPTION OF THE INVENTION The retardation film of the present invention will be specifically described below. The retardation film of the present invention,
It is formed from a cyclic olefin random copolymer in which a cyclic olefin represented by the following formula [I] or [II] and ethylene are randomly copolymerized.

[0019]

[Chemical 6] ... [I]

In the above formula [I], n is 0 or 1, m is 0 or a positive integer, and q is 0 or 1. When q is 1, the ring represented by q is a 6-membered ring, and when q is 0, this ring is a 5-membered ring.

Further, R ^{1 to} R ¹⁸ and R ^a and R
^b is each independently a hydrogen atom, a halogen atom or a hydrocarbon group. Here, the halogen atom is a fluorine atom, a chlorine atom, a bromine atom or an iodine atom. Moreover, as a hydrocarbon group, a C1-C20 alkyl group, a C1-C20 halogenated alkyl group, a C3-C15 cycloalkyl group, or an aromatic hydrocarbon group can be usually mentioned. . More specifically, as the alkyl group, a methyl group, an ethyl group, a propyl group, an isopropyl group, an amyl group, a hexyl group, an octyl group, a decyl group,
Mention may be made of dodecyl and octadecyl groups. These alkyl groups may be substituted with a halogen atom. The cycloalkyl group can include a cyclohexyl group, and the aromatic hydrocarbon group can include a phenyl group and a naphthyl group.

Further, in the above formula [I], R¹⁵And R
¹⁶And R¹⁷And R¹⁸And R¹⁵And R ¹⁷And R¹⁶And R¹⁸
And R¹⁵And R¹⁸Or, or R¹⁶And R¹⁷That's it
Combined (jointly) with each other to form a monocyclic or polycyclic group
It may be formed. And formed in this way
The monocyclic or polycyclic group may have a double bond.
Specific examples of the monocyclic or polycyclic group formed here include
The following groups can be mentioned.

[0023]

[Chemical 7]

In the above exemplification, the carbon atoms numbered 1 or 2 are each R in the formula [I].
^It represents a carbon atom to which ¹⁵ (R ¹⁶ ) or R ¹⁷ (R ¹⁸ ) is bonded. Further, R ¹⁵ and R ¹⁶ or R ¹⁷ and R ¹⁸ may form an alkylidene group. Such an alkylidene group is usually an alkylidene group having 2 to 20 carbon atoms, and examples of such an alkylidene group include an ethylidene group, a propylidene group and an isopropylidene group.

[0025]

Embedded image ... [II]

In the above formula [II], p and q are 0 or a positive integer, and m and n are 0, 1 or 2.

R ^{1 to} R ¹⁹ are each independently a hydrogen atom, a halogen atom, a hydrocarbon group or an alkoxy group. Here, the halogen atom has the same meaning as the halogen atom mentioned in the description of the above formula [I].

The hydrocarbon group usually has 1 carbon atom.
Examples include an alkyl group having 20 to 20, a cycloalkyl group having 3 to 15 carbon atoms, and an aromatic hydrocarbon group. More specifically, examples of the alkyl group include a methyl group, an ethyl group, a propyl group, an isopropyl group, an amyl group, a hexyl group, an octyl group, a decyl group, a dodecyl group and an octadecyl group. These alkyl groups may be substituted with a halogen atom. Examples of the cycloalkyl group include a cyclohexyl group, examples of the aromatic hydrocarbon group include an aryl group and an aralkyl group, and specifically, a phenyl group, a tolyl group, a naphthyl group, a benzyl group and A phenylethyl group may be mentioned.

The alkoxy group is methoxy.
Groups, ethoxy groups and propoxy groups can be mentioned.
It Further, in the formula [II], R⁹And R^TenIs joined
Carbon atom and R¹³The carbon atom to which
Is R¹¹The carbon atom to which is bound is either directly or
You may couple | bond together through the alkylene group of several 1-3.
That is, the above two carbon atoms are linked via an alkylene group.
R, if bound⁹And R¹³Or or R^Ten
And R¹¹Together with each other, methylene group (-CH₂-), Echi
Ren group (-CH₂CH ₂-) Or propylene group (-CH₂CH₂CH₂-) of
To form any of the above alkylene groups.

Further, when n = m = 0, R ¹⁵ and R ¹² or R ¹⁵ and R ¹⁹ may combine with each other to form a monocyclic or polycyclic aromatic ring. Specifically, n = m = 0
In this case, the following aromatic ring formed by R ¹⁵ and R ¹² can be mentioned.

[0031]

[Chemical 9]

Here, q has the same meaning as q in the formula [II]. Specific examples of the cyclic olefin represented by the above formula [I] or [II] include bicyclo-2-
Heptene derivative (bicyclohept-2-ene derivative), tricyclo-3-decene derivative, tricyclo-3-undecene derivative, tetracyclo-3-dodecene derivative, pentacyclo-
4-pentadecene derivative, pentacyclopentadecadiene derivative, pentacyclo-3-pentadecene derivative, pentacyclo-3-hexadecene derivative, pentacyclo-4-hexadecene derivative, hexacyclo-4-heptadecene derivative,
Heptacyclo-5-eicosene derivative, heptacyclo-4-eicosene derivative, heptacyclo-5-heneicosene derivative, octacyclo-5-docosene derivative, nonacyclo-5-pentacosene derivative, nonacyclo-6-hexacosene derivative, cyclopentadiene-acenaphthylene adduct, 1 ,Four-
Methano-1,4,4a, 9a-tetrahydrofluorene derivative, 1,4
-Methano-1,4,4a, 5,10,10a-hexahydroanthracene derivative may be mentioned.

More specific examples of the cyclic olefin represented by the above formula [I] or [II] are shown below.

[0034]

[Chemical 10]

[0035]

[Chemical 11]

[0036]

[Chemical 12]

[0037]

[Chemical 13]

[0038]

Embedded image

[0039]

[Chemical 15]

[0040]

Embedded image

[0041]

[Chemical 17]

[0042]

[Chemical 18]

[0043]

[Chemical 19]

[0044]

Embedded image

[0045]

[Chemical 21]

[0046]

[Chemical formula 22]

[0047]

[Chemical formula 23]

[0048]

[Chemical formula 24]

[0049]

[Chemical 25]

[0050]

[Chemical formula 26]

[0051]

[Chemical 27]

[0052]

[Chemical 28]

[0053]

[Chemical 29]

[0054]

[Chemical 30]

[0055]

[Chemical 31]

[0056]

[Chemical 32]

It is ethylene that forms the cyclic olefin random copolymer with the cyclic olefin as described above. However, the cyclic olefin random copolymer contains 20 mol% of structural units derived from other copolymerizable monomers other than the above-mentioned ethylene (a) and cyclic olefin (b) within a range not impairing the object of the present invention. The following may be contained, preferably in an amount of 10 mol% or less.

Specific examples of such other monomer include propylene, 1-butene, 1-pentene, 1-hexene,
3-methyl-1-butene, 3-methyl-1-pentene, 3-ethyl-1
-Pentene, 4-methyl-1-pentene, 4-methyl-1-hexene, 4,4-dimethyl-1-hexene, 4,4-dimethyl-1-pentene, 4-ethyl-1-hexene, 3-ethyl 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, 1-hexadecene, 1-octadecene and 1-eicosene, α-olefins having 3 to 20 carbon atoms, cyclobutene,
Cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, 3-methylcyclohexene, 2- (2-methylbutyl) -1-cyclohexene, cyclooctene and 3a, 5,6,7
Cycloolefins such as a-tetrahydro-4,7-methano-1H-indene, 2-norbornene, 5-methyl-2-norbornene, 5-ethyl-2-norbornene, 5-isopropyl-2-
Norbornene, 5-n-butyl-2-norbornene, 5-isobutyl-2-norbornene, 5,6-dimethyl-2-norbornene,
Norbornenes such as 5-chloro-2-norbornene and 5-fluoro-2-norbornene, 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene,
Mention may be made of non-conjugated dienes such as 1,7-octadiene, dicyclopentadiene, 5-ethylidene-2-norbornene and 5-vinyl-2-norbornene.

These other monomers can be used alone or in combination of two or more kinds. In the cyclic olefin random copolymer [A], the cyclic olefin represented by the above formula [I] or [II] has the following formula [II]
It is considered that they form a repeating unit having a structure represented by [I] or [IV].

[0060]

[Chemical 33] ... [III]

In the above formula [III], m, n, q and R ¹ to
R ¹⁸ and R ^a and R ^b have the same meanings as in the above formula [I].

[0062]

Embedded image ... [IV]

In the above formula [IV], n, m, p, q and R
^{1 to} R ¹⁹ have the same meanings as in the above formula [II].

The cyclic olefin random copolymer contains a repeating unit derived from ethylene, usually 40 to 9
It is contained in an amount of 0 mol%, preferably 50 to 85 mol%, and the repeating unit derived from a cyclic olefin is usually 10 to 60 mol%, preferably 1
It is contained in an amount within the range of 5 to 50 mol%. The repeating units derived from ethylene and the repeating units derived from cyclic olefin are randomly arranged, and these repeating units are arranged substantially linearly.

The cyclic olefin random copolymer is obtained by, for example, adding ethylene and the above cyclic olefin to a hydrocarbon soluble vanadium compound and an organoaluminum in a hydrocarbon medium or a cyclic olefin which is liquid at the reaction temperature among the above cyclic olefins. Or a catalyst comprising a group IV or lanthanide transition metal compound containing a ligand having a cyclopentadienyl skeleton, an organoaluminum oxy compound, and optionally an organoaluminum compound. ) It can be produced by polymerizing in the presence of.

Such a polymerization method itself is already known and disclosed in JP-A-60-168708, 61-120816 and 61-115912.
No. 61-115916, No. 61-271308, No. 61-272216,
Produced by appropriately selecting the conditions according to the method proposed by the applicant in the publications such as 62-252406 and 62-252407, and the specifications such as Japanese Patent Application Nos. 61-95905 and 61-95906. can do.

[0067] Specifically, in a cyclohexane medium using a continuous polymerization apparatus, tetracyclo [4.4.0.1 ^2,5 .1 ^7,10] As the cyclic olefin-3- dodecene (hereinafter "TC
D-3 "may be abbreviated) and V is used as a catalyst.
O (OCH ₂ CH ₃ ) Cl ₂ / Al (CH ₂ CH ₃ ) _1.5 Cl
_An ethylene / TCD-3 random copolymer can be produced by copolymerizing _1.5 with _1.5 ° C. and setting the reaction time (polymerization reaction residence time) to about 30 minutes.

A part of the above-mentioned cyclic olefin random copolymer may be modified with an unsaturated carboxylic acid such as maleic anhydride. Such a modified product may be produced by reacting the above cyclic olefin random copolymer with an unsaturated carboxylic acid, an anhydride thereof, or a derivative such as an alkyl ester of an unsaturated carboxylic acid. You can The modification ratio of the modified cyclic olefin random copolymer in this case is usually 50 mol% or less, preferably 10 mol% or less.

The modified cyclic olefin random copolymer is
It can be produced by graft-polymerizing a modifier with the cyclic olefin random copolymer. This graft polymerization includes, for example, a method in which a cyclic olefin random copolymer is melted and a modifier is added to perform graft polymerization, or a cyclic olefin random copolymer and a modifier are dissolved in a solvent to perform graft polymerization.
A radical initiator is preferably used in this graft polymerization. The graft polymerization temperature is usually 60 to 3
50 ° C.

Further, such a modified cyclic olefin random copolymer is a cyclic olefin random copolymer,
It can be produced by adding a modifier in an amount such that a desired modification ratio is obtained and performing graft polymerization, or by preparing a modified product having a high modification ratio in advance, and then modifying this modified product with an unmodified cyclic olefin random It can also be produced by mixing with a copolymer.

The cyclic olefin random copolymer used in the present invention has an intrinsic viscosity measured in decalin at 135 ° C. of usually 0.01 to 20 dl / g, preferably 0.05.
It is in the range of -10 dl / g, particularly preferably 0.08-8 dl / g.

This cyclic olefin random copolymer is
Generally it is amorphous or low crystalline, preferably amorphous. Therefore, the film formed from this cyclic olefin random copolymer has high transparency.

With respect to this cyclic olefin random copolymer, the crystallinity measured by X-ray is 5% or less, most of which is 0%, and a clear melting point is not observed by a differential scanning calorimeter (DSC). There are many.

The cyclic olefin random copolymer has a glass transition temperature (Tg) and a softening temperature (TMA).
Has the characteristic of high. The glass transition temperature (Tg) of this copolymer is usually 50 to 230 ° C, preferably 70 to 200 ° C. The softening temperature of the cyclic olefin random copolymer is usually 70 to 250.
C., preferably in the range of 90 to 220.degree.

The thermal decomposition temperature of this copolymer is usually in the range of 350 to 420 ° C, and most of it in the range of 370 to 400 ° C. As mechanical properties, the flexural modulus of the copolymer itself is in a normally 1 × 10 ⁴ ~5 × 10 ⁴ in the range of Kg / cm ^2, bending strength in the range of usually 300~1500Kg / cm ² is there.

The density of the resin itself is usually 0.8.
6 to 1.10 g / cm ³ , most of which is 0.88 to 1.08 g /
It is in the range of cm ³ . The refractive index measured by ASTM D542 is usually 1.47 to 1.58, and most of them are 1.4.
Within the range of 8 to 1.56, and further ASTM D1
The haze measured by 003 is usually 20% or less, and most is 10% or less.

As an electric property, the dielectric constant (1 KHz) of this copolymer measured by ASTM D150.
Is usually from 1.5 to 3.0, often from 1.9 to 2.6, the dielectric loss tangent is usually from 9 × 10 ⁻⁴ to 8 × 10 ⁻⁵ , and most is from 3 × 10 ^{−4 to} 9 ×.
It is in the range of 10 ⁻⁵ .

The film formed from such a cyclic olefin random copolymer has excellent resistance to acids, alkalis and polar solvents, and molded products are treated with sulfuric acid, ammonia water,
Even when immersed in acetone or ethyl acetate for 24 hours, discoloration, deterioration of transparency, generation of cracks, deformation, dissolution of resin, etc. do not occur.

In the present invention, the above-mentioned softening temperature (TMA) is the ThermoMechanical Analys manufactured by DuPont.
It was specified by measuring the thermal deformation behavior of a 1 mm thick sheet using er. That is, a quartz needle was placed on the sheet, a load of 49 g was applied to the quartz needle, the temperature was raised at a rate of 5 ° C./min, and the temperature when the needle entered the sheet 0.635 mm was taken as TMA.

In the present invention, the above-mentioned cyclic olefin random copolymer and modified products thereof can be used alone or in combination. Further, the cyclic olefin random copolymer as described above has a transparency when mixed with the cyclic olefin random copolymer such as a cyclic olefin ring-opening polymer and a hydrogenated product of the cyclic olefin ring-opening polymer. Other resins that can be maintained can be blended and used.

Further, the cyclic olefin random copolymer includes heat resistance stability, weather resistance stability, antistatic agent, slip agent, antiblocking agent, antifogging agent, lubricant, dye,
Natural oils, synthetic oils, waxes and the like can be added.

For example, as a stabilizer compounded as an optional component, tetrakis [methylene-3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate] methane,
β- (3,5-di-t-butyl-4-hydroxyphenyl) propionic acid alkyl ester, 2,2'-oxamide bis [ethyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) Phenolic antioxidants such as propionate, fatty acid metal salts such as zinc stearate, calcium stearate, calcium 1,2-hydroxystearate, glycerin monostearate, glycerin distearate, pentaerythritol monostearate, pentaerythritol distearate And polyhydric alcohol fatty acid esters such as pentaerythritol tristearate. These may be blended alone or in combination. For example, tetrakis [methylene-3
Examples include a combination of-(3.5-di-t-butyl-4-hydroxyphenyl) propionate] methane, zinc stearate and glycerin monostearate.

The retardation film of the present invention is a uniaxially stretched film of the above cyclic olefin random copolymer. That is, in order to form the retardation film of the present invention,
The retardation film of the present invention can be produced by producing an unstretched film composed of the cyclic olefin random copolymer and uniaxially stretching the unstretched film.

The unstretched film can be produced by using a known film forming method such as a solvent casting method, a calendering method, an extrusion method or a hot pressing method. The retardation film of the present invention can be formed by uniaxially stretching this unstretched film. For the uniaxial stretching, known uniaxial stretching methods such as a transverse uniaxial stretching method using a tenter, a longitudinal uniaxial stretching method using at least a pair of rolls having different peripheral speeds, and a roll-to-roll compression stretching method are adopted. can do.

Stretching in such a uniaxial stretching method is carried out at a temperature of the cyclic olefin random copolymer to be stretched, which is equal to or higher than the glass transition temperature (Tg) of the copolymer and is equal to or lower than the temperature at which the unstretched film can be maintained in a specific state. The heating is performed at a temperature 5 to 50 ° C. higher than the glass transition temperature, preferably 10 to 25 ° C. higher than the glass transition temperature. When the stretching temperature is low, stress tends to concentrate during stretching, and the retardation unevenness (dispersion of retardation value) in the obtained stretched film tends to increase. When the temperature is too high, birefringence of the stretched film develops. Since it becomes difficult to perform stretching at a high stretching ratio in order to obtain a desired birefringence, unevenness in retardation tends to increase and neck-in during stretching tends to increase.

The stretching ratio (area) can be appropriately set depending on the thickness of the unstretched film and the stretching ratio, but is usually 1.1 to 3 times, preferably 1.15 to 2.1 times. If the draw ratio is low, the birefringence will be low, and it will be difficult to obtain a film having a sufficient retardation value, and if the draw ratio is too high, the retardation value of the obtained film will be large and the neck-in will be increased during production. It is easy to cause problems such as.

A film stretched so that the amount of stretching is reduced at the final stage of stretching is preferable. In this way, the retardation film produced by reducing the stretching amount in the final stage of stretching is less likely to remain colored when the liquid crystal display to which this is attached is viewed obliquely, and thus this retardation film is used. By so doing, it is possible to form a so-called liquid crystal display having a wide field of view.

The retardation value of the retardation film of the present invention must be in the range of 100 to 800 nm, and this retardation value is 150 to 700.
It is preferably within the range. That is, by setting the retardation value within the above range, the transmission of visible light (wavelength range λ = 400 to 700 nm) used in liquid crystal displays and the like becomes high.

Further, the phase unevenness in the retardation film of the present invention needs to be 15 nm or less, and more preferably the phase unevenness is 10 nm or less.
By setting the phase unevenness to 15 nm or less, the liquid crystal display can be used without causing color unevenness.

In the present invention, the retardation value is a value defined as the product (Δn × d) of the birefringence (Δn) of the film and the thickness (d) of the film, and the phase unevenness is It is the variation of the retardation value in the same film.

The retardation film 2 of the present invention is shown in FIG.
As shown in FIG. 3, it is attached via the adhesive layer 5 on the substrate 1 forming the liquid crystal cell. Then, usually, the polarizing film 3 is laminated on the retardation film 2 via the adhesive layer 5, and the protective film is similarly laminated on the polarizing film 3 via the adhesive layer 5. It

The retardation film of the present invention is attached to each surface of two substrates forming a liquid crystal cell in a light transmissive liquid crystal display. When two retardation plates are arranged in this way, the polarizing film 3 is arranged in the cross nicro position. The reflective liquid crystal display is attached to the surface of the substrate on the display side.

The retardation film of the present invention is used for a liquid crystal display adopting the STN system, particularly for a monochrome or color liquid crystal display adopting the STN system.

[0094]

The retardation film of the present invention is formed from a uniaxially stretched cyclic olefin copolymer having a retardation value in the range of 200 to 800 nm and a phase unevenness of 15 nm or less. In addition to exhibiting good retardation, it has high transparency and excellent properties such as moisture resistance, dimensional stability, solvent resistance, heat resistance stability and light resistance stability.

Particularly, the uniaxially stretched film formed from the cyclic olefin random copolymer has a very low content of impurities, and therefore exhibits excellent retardation and high transparency.
Further, since the cyclic olefin random copolymer has a low water vapor permeability, the moisture resistance is high, and since the cyclic olefin random copolymer does not have an unsaturated bond, the heat resistance is also good. Moreover, the light stability is also high.

[0096]

The present invention will now be described in more detail with reference to examples of the present invention, but the present invention is not limited thereto.

[0097]

As Example 1 random copolymer of cyclic olefin and ethylene, ethylene and tetracyclo [4,4,0,1 ^2.5, 1
^7.10 ] -3-Random copolymer with dodecene (hereinafter abbreviated as "TCD-3") [intrinsic viscosity: 0.61 dl / g, TM
A: 115 ° C.] and unstretched thickness of 200 μ in a single screw extruder (30 mmφ) at a cylinder temperature of 250 ° C.
m sheets were produced.

A batch type stretching device (Toyo Seiki Co., Ltd.)
(Manufactured by K.K.) at an ambient temperature of 135 ° C. for 5 minutes, and then uniaxially stretched at a stretching speed of 1.5 m / sec to obtain a uniaxially stretched film having a stretch ratio of 1.5 times.

Table 1 shows the retardation value of the obtained uniaxially stretched film and its variation.

[0100]

Examples 2-3: Ethylene / TCD- used in Example 1
A uniaxially stretched film was obtained in the same manner except that an ethylene / TCD-3 copolymer having a different intrinsic viscosity and TMA was used instead of the 3 copolymer.

Table 1 shows the retardation value of the obtained uniaxially stretched film and its variation.

[0102]

[Table 1]

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an example of a mode in which a retardation film of the present invention is attached to a liquid crystal display.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Substrate 2 ... Retardation film 3 ... Polarizing film 4 ... Protective film 5 ... Adhesive layer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Office reference number FI technical display location B29K 23:00 B29L 11:00

Claims (1)

[Claims] 1. A ring represented by the following formula [I] or [II]:
Consisting of a random copolymer of ethylene oxide and ethylene
It is formed from a uniaxially stretched film and has a retardation value
It is in the range of 200 to 800 nm and the phase unevenness is 15 nm or less.
A retardation film characterized by being below;[I] [In the above formula [I], n is 0 or 1, and m is 0 or
Is a positive integer, q is 0 or 1, and R is¹~ R¹⁸
And R^aAnd R^bAre independently hydrogen
Child, a halogen atom or a hydrocarbon group, R¹⁵~ R¹⁸
May be bonded to each other to form a monocycle or polycycle.
And the monocycle or polycycle may have a double bond.
Again, R¹⁵And R¹⁶Or with or R¹⁷And R¹⁸And with
Ridene group may be formed],... [II] [In the above formula [II], p and q are 0 or an integer of 1 or more.
And m and n are 0, 1 or 2, R¹~ R
¹⁹Are each independently a hydrogen atom, a halogen atom, a fat
Group hydrocarbon group, alicyclic hydrocarbon group, aromatic hydrocarbon group
Or is an alkoxy group, R⁹Or R^TenAre bound
Carbon atom and R¹³The carbon atom to which is bound or R¹¹
The carbon atom to which is bonded is either directly or has 1 carbon atom.
~ 3 may be bonded via an alkylene group,
And when n = m = 0, R¹⁵And R ¹²Or R¹⁵And R¹⁹When
Combine with each other to form a monocyclic or polycyclic aromatic ring
You can stay there.]