JP2019124781A - Method of manufacturing optical compensation film - Google Patents

Abstract

To provide a method of manufacturing an optical compensation film suitable for an optical material, in particular, a method of manufacturing an optical compensation film featuring superior retardation properties, wavelength dependence, and retardation stability while being heated.SOLUTION: A method of manufacturing an optical compensation film is provided, comprising stretching a film containing a fumaric acid ester-based polymer resin at a temperature of 50-200°C by one axis or more, and then heating the stretched film being held steady at 100-200°C for 1 to 15 minutes to obtain the optical compensation film.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing an optical compensation film suitable as an optical material, and more particularly to a method for producing an optical compensation film which is excellent in retardation properties, wavelength dependency, and retardation stability at the time of heating.

  Liquid crystal displays are widely used as mobile phones, computer monitors, laptops and TVs as the most important display devices in the multimedia society. Many optical films are used for liquid crystal displays in order to improve display characteristics. In particular, the optical compensation film plays an important role in improving the contrast when viewed from the front or obliquely and compensating the color tone. Although polycarbonate and cyclic polyolefin are used as a conventional optical compensation film, all of these polymers are polymers having positive birefringence. Here, the positive and negative of birefringence are defined as shown below.

  The optical anisotropy of a polymer film molecularly oriented by stretching or the like can be represented by a refractive index ellipsoid shown in FIG. Here, when the film is stretched, the refractive index in the fast axis direction in the film plane is nx, the refractive index in the vertical direction is ny, and the refractive index in the thickness direction of the film is nz. The fast axis is an axial direction with a low refractive index in the film plane.

  The negative birefringence means that the stretching direction is the fast axis direction, and the positive birefringence is that the direction perpendicular to the stretching direction is the fast axis direction.

  That is, in uniaxial stretching of a polymer having negative birefringence, the refractive index in the stretching axis direction is small (advancing axis: stretching direction), and in uniaxial stretching of a polymer having positive birefringence, an axis orthogonal to the stretching axis direction The refractive index in the direction is small (fast axis: orthogonal to the stretching direction).

  Further, the in-plane retardation (Re) is represented as a value obtained by multiplying the thickness of the film by the refractive index (ny) in the direction orthogonal to the fast axis direction and the refractive index (nx) in the fast axis direction.

  Many polymers have positive birefringence. Examples of polymers having negative birefringence include acrylic resins and polystyrenes. However, the acrylic resins have a low expression of retardation, and the properties as an optical compensation film are not sufficient. Polystyrene has a large photoelastic coefficient in a room temperature region, a problem of stability of retardation, such as a change in retardation due to a slight stress, a problem on optical characteristics such as a large wavelength dependency of retardation, and further a low heat resistance. There are practical problems such as, and are not used at present.

  Here, the wavelength dependency of the retardation means that the retardation changes depending on the measurement wavelength, and the ratio of the retardation (R450) measured at a wavelength of 450 nm and the retardation (R550) measured at a wavelength of 550 nm It can be represented as R450 / R550. Generally, in polymers having an aromatic structure, this R450 / R550 tends to be large, and the contrast and viewing angle characteristics in a low wavelength region are degraded.

  A stretched film of a polymer exhibiting negative birefringence has a high refractive index in the thickness direction of the film and becomes an optical compensation film which has not been used in the prior art, and thus, for example, super twisted nematic liquid crystal (STN-LCD) or vertically aligned liquid crystal Optical compensation film for compensating the viewing angle characteristics of displays such as in-plane oriented liquid crystal (IPS-LCD), reflective liquid crystal display, semi-transmissive liquid crystal display, etc. There is strong market demand for optical compensation films that are useful as films and have negative birefringence.

  As an optical compensation film having such negative birefringence, there has been proposed a method for producing a film in which the refractive index in the thickness direction of the film is increased using a polymer having positive birefringence. One is a method of adhering a heat-shrinkable film to one side or both sides of a polymer film, and subjecting the laminate to heat drawing treatment to apply a shrinking force in the thickness direction of the polymer film (see, for example, Patent Documents 1 to 3) ). In addition, a method of uniaxially stretching in a plane while applying an electric field to a polymer film has been proposed (see, for example, Patent Document 4). In addition, an optical compensation film composed of fine particles having negative optical anisotropy and a transparent polymer has been proposed (see, for example, Patent Document 5).

  However, the methods proposed in Patent Documents 1 to 4 have a problem that they are inferior in productivity because the manufacturing process becomes very complicated. Further, control of the uniformity of the retardation and the like becomes significantly more difficult as compared with the control by the conventional stretching. Furthermore, there is a problem that the wavelength dependency of the phase difference is large.

  In addition, the optical compensation film obtained in Patent Document 5 is an optical compensation film having negative birefringence by adding fine particles having negative optical anisotropy, and from the viewpoint of simplification of the production method and economy. There is a need for an optical compensation film that does not require the addition of fine particles.

  In addition, a method using a polymer having negative birefringence has been proposed, and for example, an optical compensation film or an optical compensation layer in which a liquid crystalline polymer film is applied and homeotropic alignment is proposed (for example, a patent) Reference 6). In addition, an optical compensation film coated with an aromatic polymer such as polyvinyl naphthalene or polyvinyl biphenyl has been proposed (see, for example, Patent Document 7 and Non-Patent Document 1). Also, an optical film using a polyvinylcarbazole-based polymer has been proposed (see, for example, Patent Document 8). Furthermore, a retardation film comprising a fumaric acid ester-based resin has been proposed (see, for example, Patent Document 9).

  However, the method described in Patent Document 6 has a problem that it is difficult to uniformly align the liquid crystalline polymer homeotropically. Further, the methods described in Patent Documents 7 and 8 and Non-patent Document 1 have the problem that the obtained film is easily broken and the wavelength dependency of retardation is large, and the photoelastic coefficient in the glass region is high. There is a problem that the phase difference is not stable.

  Although the retardation film obtained in Patent Document 9 is excellent in optical characteristics such as retardation characteristics and wavelength dependency, when it is used as a polarizing plate member requiring durability at high temperature, There is a problem in the phase difference stability, and improvement of phase difference stability has been desired.

Patent No. 2818983 Japanese Patent Application Laid-Open No. 05-297223 Japanese Patent Application Laid-Open No. 05-323120 Japanese Patent Application Laid-Open No. 06-088909 JP 2005-156862 A JP 2002-333524 A JP, 2006-221116, A JP, 2001-91746, A JP, 2008-64817, A

Journal of The Society of Rheology, Vol. 22, no. 2, 129-134 (1994)

  The present invention has been made in view of the above problems, and an object thereof is to provide a method for producing an optical compensation film excellent in optical characteristics such as retardation characteristics, wavelength dependency, retardation stability during heating, and the like. It is.

  MEANS TO SOLVE THE PROBLEM As a result of earnestly examining in order to solve the said subject, the present inventors discover that the manufacturing method which carries out the drawing process of the film containing specific resin on specific conditions solves the said subject, and completes this invention It came to

  That is, the present invention stretches a film containing a fumaric acid ester-based polymer resin at 50 ° C. to 200 ° C. uniaxially or more, and then continuously fixes the stretched film at 100 ° C. to 200 ° C. for 1 minute to The present invention relates to a method for producing an optical compensation film characterized by obtaining an optical compensation film by heating and holding for 15 minutes.

  Hereinafter, the present invention will be described in detail.

  In the method for producing an optical compensation film of the present invention, a film containing a fumaric acid ester polymer resin is stretched at 50 ° C. to 200 ° C. uniaxially or more, and then the stretched film is continuously fixed at 100 ° C. to 200 The optical compensation film is produced by heating and holding at 1 ° C for 1 minute to 15 minutes.

  As a fumaric acid ester-based polymer resin used in the present invention, a fumaric acid represented by the following general formula (1) can be provided because it is possible to provide a film which is particularly excellent in optical compensation performance, heat resistance, mechanical properties and the like. A fumaric acid ester-based polymer resin containing 30 mol% or more of ester residue units is preferable, a fumaric acid ester-based polymer resin containing 50 mol% or more is more preferable, and a fumaric acid ester-based polymer resin containing 70 mol% or more Is particularly preferred.

(Wherein, R ₁ and R ₂ each independently represent an alkyl group having 1 to 12 carbon atoms)
Here, R ₁ and R ₂ which are ester substituents of the fumaric acid ester residue unit of the general formula (1) are each independently an alkyl group having 1 to 12 carbon atoms, and are halogen groups such as fluorine and chlorine An ether group; optionally substituted by an ester group or an amino group; for example, ethyl group, isopropyl group, n-butyl group, s-butyl group, t-butyl group, s-pentyl group, t-pentyl group, One or more kinds such as s-hexyl group, t-hexyl group, cyclopropyl group, cyclopentyl group, cyclohexyl group, 2-ethylhexyl group, n-octyl group and the like can be mentioned, and in particular, they are excellent in heat resistance and mechanical properties It is preferable to be an ethyl group, isopropyl group, n-butyl, 2-ethylhexyl group, n-octyl group etc., since an optical compensation film is obtained, and an isopropyl group is more preferable. There.

  Specific examples of the fumaric acid ester residue unit represented by the general formula (1) include diethyl fumarate residue, diisopropyl fumarate residue, di-n-butyl fumarate residue, di-s-butyl fumarate Residue, fumarate di-t-butyl residue, fumarate di-s-pentyl residue, fumarate di-s-hexyl residue, fumarate di-t-hexyl residue, fumarate di-cyclopropyl residue And one or more kinds of groups such as fumaric acid di-cyclopentyl residue, fumaric acid di-cyclohexyl residue, fumaric acid bis (2-ethylhexyl) residue, fumaric acid di-n-octyl residue, etc. Among them, an optical compensation film having excellent heat resistance and mechanical properties is obtained. Thus, a fumaric acid diisopropyl residue, a fumaric acid diethyl residue, a fumaric acid di-n-butyl residue, a fumaric acid di-2-ethylhexyl residue, Preferably such circle di -n- octyl residues, more preferably diisopropyl fumarate residue.

  Specific fumaric acid ester-based polymer resins include, for example, diisopropyl fumarate polymer, di-n-butyl fumarate polymer, diisopropyl fumarate / dimethyl fumarate copolymer, diisopropyl fumarate / diethyl fumarate copolyester Polymers, diisopropyl fumarate, di-n-butyl fumarate copolymer, diisopropyl fumarate, bis (2-ethylhexyl) fumarate copolymer, diisopropyl fumarate, di-n-octyl fumarate copolymer, etc. Among them, an optical compensation film having excellent heat resistance and mechanical properties can be obtained. Thus, a diisopropyl fumarate polymer, diisopropyl fumarate / diethyl fumarate copolymer, diisopropyl fumarate / bis (2-ethylhexyl) fumarate may be used. Polymer, fumaric acid diisopropyl, fumaric acid di-n-octyl Polymers are preferred.

  In addition, the fumaric acid ester-based polymer resin constituting the optical compensation film of the present invention may contain other monomer residues, as long as the object of the present invention is not deviated, and the other single monomers may be contained. As a monomer residue, for example, styrene residues such as styrene residue and α-methylstyrene residue; acrylic acid residue; methyl acrylate residue, ethyl acrylate residue, butyl acrylate residue, acrylic Acrylic acid esters such as 3-ethyl-3-oxetanyl methyl residue, tetrahydrofurfuryl residue, etc .; methacrylic acid residue; methyl methacrylate residue, ethyl methacrylate residue, butyl methacrylate residue Methacrylate residues such as 3-ethyl-3-oxetanyl methyl residue, tetrahydrofurfuryl residue of methacrylic acid; vinyl acetate Groups, vinyl esters such as vinyl propionate, vinyl ethers such as methyl vinyl ether, ethyl vinyl ether and butyl vinyl ether; acrylonitriles; methacrylonitriles; ethylenes and propylenes 1 type, or 2 or more types, such as olefins residue, such as a residue, can be mentioned.

The fumaric acid ester-based polymer resin is particularly excellent in mechanical properties and excellent in molding processability at the time of film formation, so it can be obtained from an elution curve measured by gel permeation chromatography (GPC). The number average molecular weight (Mn) in terms of standard polystyrene is preferably 1 × 10 ^{3 to} 5 × 10 ⁶ , and more preferably 5 × 10 ^{4 to} 5 × 10 ⁵ .

  The method for producing the fumaric acid ester-based polymer resin constituting the optical compensation film of the present invention is not particularly limited as long as the fumaric acid ester-based polymer resin is obtained, and for example, radical polymerization of fumaric acid esters is performed. It can be manufactured by

  Moreover, as radical polymerization to be used, it can carry out by a well-known polymerization method, For example, any of mass polymerization method, solution polymerization method, suspension polymerization method, precipitation polymerization method, emulsion polymerization method etc. can be adopted. is there.

  As a polymerization initiator at the time of performing a radical polymerization method, for example, benzoyl peroxide, lauryl peroxide, octanoyl peroxide, acetyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide Organic peroxides such as oxides, t-butylperoxyacetate, t-butylperoxybenzoate, t-butylperoxypivalate; 2,2'-azobis (2,4-dimethylvaleronitrile), 2,2 ' -Azo such as -azobis (2-butyronitrile), 2,2'-azobisisobutyronitrile, dimethyl-2,2'-azobisisobutyrate, 1,1'-azobis (cyclohexane-1-carbonitrile), etc. Examples include initiators and the like.

  And there is no restriction in particular as a solvent which can be used in solution polymerization method, suspension polymerization method, precipitation polymerization method, emulsion polymerization method, for example, aromatic solvents such as benzene, toluene, xylene, etc .; methanol, ethanol, propyl alcohol, butyl Examples thereof include alcohol solvents such as alcohol; cyclohexane; dioxane; tetrahydrofuran (THF); acetone; methyl ethyl ketone; dimethylformamide; isopropyl acetate; water and the like, and mixed solvents thereof are also mentioned.

  Moreover, the polymerization temperature at the time of performing radical polymerization can be suitably set according to the decomposition temperature of a polymerization initiator, and generally it is preferable to carry out in 40-150 degreeC.

  As the suspension polymerization method in the present invention, known radical suspension polymerization methods can be adopted, and there is no particular limitation as long as an aqueous medium is used. Moreover, there is no restriction | limiting in particular as an aqueous medium, For example, water, industrial water, ion-exchange water, distilled water etc. can be mentioned.

  It is possible to use a dispersant generally used in the suspension polymerization method, and the dispersant is not particularly limited, and a known dispersant can be used, for example, polyvinyl alcohol such as polyvinyl alcohol Dispersing agents: Cellulose based dispersing agents such as methyl cellulose, ethyl cellulose, propyl cellulose hydroxymethyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxyethyl methyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, carboxyethyl cellulose etc .; Inorganic compounds such as calcium phosphate etc. Among them, a cellulose-based dispersant is preferable, and hydroxypropyl methylcellulose is more preferable, because suspension polymerization becomes more stable.

  The mixing ratio of the aqueous medium, the monomer, the dispersant, and the polymerization initiator in the method for producing the fumaric acid ester-based polymer resin of the present invention can be appropriately selected according to the quality of the desired fumaric acid ester-based polymer Among them, 50 to 150 parts by weight of a monomer, and 0.01 to 20 parts by weight of a dispersing agent with respect to 100 parts by weight of an aqueous medium, since it is a method for producing a fumaric acid ester-based polymer resin more excellent in production efficiency. It is preferable to use it as 0.001 to 5 parts by weight of an oil-soluble radical polymerization initiator.

  There is no restriction | limiting in particular as a reaction apparatus in the suspension polymerization method in this invention, A well-known apparatus can be used, For example, it is a reaction kettle provided with a stirring blade, a temperature control apparatus, etc., Glass lining (GL And stainless steel (SUS) reaction pots and the like. Further, as the stirring blade, for example, a paddle blade, four paddle blades, an anchor blade, three receding blades, six turbine blades, a blue margin blade and the like can be mentioned.

  There is no restriction | limiting in particular as a manufacturing method of a film containing fumaric acid ester polymer resin in the manufacturing method of the optical compensation film of this invention, For example, methods, such as a solution casting method and a melt casting method, etc. are mentioned.

  The solution casting method is a method of casting a solution (hereinafter referred to as a dope) in which a fumaric acid ester polymer resin is dissolved in a solvent, and removing the solvent by heating or the like to obtain a film. At that time, as a method of casting the dope on the support substrate, for example, a T-die method, a doctor blade method, a bar coater method, a roll coater method, a lip coater method or the like is used. Particularly, industrially, the method of continuously extruding the dope from the die to a belt-like or drum-like support substrate is the most common. As a support substrate to be used, for example, a glass substrate; a metal substrate such as stainless steel or ferro type; a plastic substrate such as polyethylene terephthalate (PET), triacetyl cellulose (TAC), etc. may be mentioned. In forming a film having high transparency and excellent thickness accuracy and surface smoothness in the solution casting method, the solution viscosity of the dope is an extremely important factor, and 700 to 30,000 cps is preferable, and 1,000 It is further preferable that it is-10000 cps.

  The melt casting method is a molding method in which a fumaric acid ester polymer resin is melted in an extruder, extruded from a slit of a T-die into a film, and then cooled while being cooled by a roll, air or the like.

  And in the manufacturing method of the optical compensation film of this invention, a phase difference is controlled by extending | stretching the film obtained by the above at 50 degreeC-200 degreeC uniaxially or more. Here, in the present invention, when the temperature at the time of the stretching is not 50 ° C. to 200 ° C., the retardation performance is inferior. In the present invention, the temperature at the time of the stretching is preferably 80 ° C to 180 ° C.

  When the stretching is performed, examples of the stretching method in which uniaxial stretching is performed include free width uniaxial stretching, a method of stretching with a tenter, a method of stretching between rolls, and the like. The method of extending | stretching with a tenter, the method of making it expand in tube shape, and extending | stretching etc. are mentioned.

  The thickness of the film at the time of stretching is preferably 10 to 200 μm, more preferably 30 to 180 μm, and particularly preferably 30 to 150 μm, from the viewpoint of ease of stretching and compatibility with thinning of the optical member.

  As the stretching conditions, a thickness ratio is unlikely to be generated, and an optical compensation film excellent in mechanical properties and optical properties is obtained. Therefore, the stretching ratio is preferably 1.01 to 3 times, more preferably 1.01 to 2 It is a double.

  In the method for producing an optical compensation film of the present invention, after the film is stretched, the stretched film is heated and held at 100 ° C. to 200 ° C. for 1 minute to 15 minutes while being fixed. In the present invention, when the stretched film is not heated and kept at 100 ° C. to 200 ° C. for 1 minute to 15 minutes while being stretched, the obtained optical compensation film is inferior in retardation stability at heating It becomes a thing. In the present invention, heating and holding at 120 ° C. to 180 ° C. for 1 minute to 10 minutes is preferable.

  When fixing the stretched film, the fixing method is not particularly limited. For example, heating may be performed in a state in which the film is gripped by a clip, a pin or the like in a tenter.

  Moreover, there is no restriction | limiting in particular in the temperature at the time of taking out a film after said heating holding | maintenance, You may give rapid cooling by ventilation, slow cooling in the air, etc.

  The optical compensation film obtained by the method for producing an optical compensation film of the present invention is excellent in retardation properties, wavelength dependency and the like, so the refractive index in the fast axis direction in the film plane is nx, perpendicular to that Assuming that the refractive index in the direction is ny and the refractive index in the thickness direction of the film is nz, there is a relationship of nx ≦ ny <nz, and the retardation measured with light of 450 nm and the retardation measured with light of 550 nm The ratio (R450 / R550) is preferably 1.1 or less.

  Further, since the optical compensation film becomes an optical compensation film having more excellent optical properties, the in-plane retardation (Re) measured at a wavelength of 550 nm represented by the following formula (1) is 0 to 300 nm It is preferably, further preferably 0 to 290 nm, and particularly preferably 0 to 280 nm.

Re = (ny-nx) x d (1)
(Here, d represents the thickness of the film.)
In addition, the in-plane retardation (Re) when used as a circularly polarizing film formed by laminating and integrating the optical compensation film and a polarizing plate is preferably 100 to 200 nm because it has excellent optical compensation performance. . Here, the circularly polarizing film is useful for an antireflection film such as an organic EL display, a brightness enhancement film, and the like in addition to a compensation film for a reflective liquid crystal display.

  The optical compensation film preferably has an out-of-plane retardation (Rth) of -30 to -300 nm, more preferably -50 to -300 nm, measured at a wavelength of 550 nm as shown by the following formula (2). And particularly preferably from -80 to -300 nm.

Rth = [(nx + ny) / 2-nz] × d (2)
The optical compensation film is excellent in retardation stability, and is also useful for polarizing plate applications that require high retardation stability even in a high heat environment.

  The optical compensation film obtained by the method for producing an optical compensation film of the present invention is suitable for obtaining an optical compensation film having higher retardation stability, so the optical compensation film is heat-treated at 90 ° C. for 24 hours After the heat treatment, the ratio (retention ratio) of the out-of-plane retardation before and after the heat treatment represented by the following formula (3) is preferably 97% or more, and more preferably 98% or more.

Retention rate = Rth ₂ / Rth ₁ x 100 (3)
(Here, Rth ₁ represents the out-of-plane retardation before heat treatment, and Rth ₂ represents the out-of-plane retardation after heat treatment.)
The thickness of the optical compensation film is preferably 5 to 100 μm, more preferably 10 to 80 μm, and particularly preferably 10 to 60 μm.

  The optical compensation film is preferably blended with an antioxidant in order to enhance the heat stability of the film formation or the film itself. Examples of the antioxidant include hindered phenol-based antioxidants, phosphorus-based antioxidants, other antioxidants and the like, and these antioxidants may be used alone or in combination. And, it is preferable to use a hindered phenol-based antioxidant and a phosphorus-based antioxidant in combination, because the antioxidant action is synergistically improved, and in that case, for example, 100 parts by weight of a hindered phenol-based antioxidant Preferably, 100 to 500 parts by weight of a phosphorus-based antioxidant is used by mixing. The addition amount of the antioxidant is preferably 0.01 to 10 parts by weight, more preferably 0.5 to 1 parts by weight with respect to 100 parts by weight of the fumaric acid ester-based polymer resin constituting the optical compensation film. preferable.

  Furthermore, as an ultraviolet absorber, for example, an ultraviolet absorber such as benzotriazole, benzophenone, triazine, benzoate and the like may be blended as needed.

  The optical compensation film may contain other polymers, surfactants, polymer electrolytes, conductive complexes, inorganic fillers, pigments, dyes, antistatic agents, antiblocking agents, lubricants, and the like.

  The optical compensation film of the present invention may be laminated with a polarizing plate to be used as a circular or elliptical polarizing plate, or may be laminated with a polarizer made of polyvinyl alcohol / iodine or the like to form a polarizing plate. Moreover, it can also be laminated | stacked with the optical compensation films of this invention, or another optical compensation film.

  According to the present invention, it is an optical film having a large refractive index in the thickness direction of the film, a small wavelength dependency, and excellent retardation stability during heating, which is useful as a compensation film or an antireflective film for contrast and viewing angle characteristics of a liquid crystal display. A compensation film can be provided.

Change of refractive index ellipsoid by stretching

  Hereinafter, the present invention will be described by way of examples, but the present invention is not limited to these examples. In addition, unless otherwise indicated, the used reagent used the commercial item.

  In addition, the various physical properties shown by the Example were measured by the following method.

<Measurement of number average molecular weight>
Measured at 40 ° C using tetrahydrofuran as a solvent using a gel permeation chromatography (GPC) apparatus (made by Tosoh, trade name: C0-8011 (column GMH _HR -H)), and converted to standard polystyrene Asked as.

<Analysis of polymer>
The structural analysis of the polymer was obtained from proton nuclear magnetic resonance spectroscopy ( ¹ H-NMR) spectrum analysis using a nuclear magnetic resonance measurement apparatus (manufactured by Nippon Denshi, trade name: JNM-GX 270).

<Measurement of light transmittance and haze of optical compensation film>
The light transmittance and haze of the produced optical compensation film were measured using a haze meter (trade name: NDH 2000, manufactured by Nippon Denshoku Industries Co., Ltd.), and the light transmittance was measured according to JIS K 7361-1 (1997 edition). The haze was measured in accordance with JIS-K 7136 (2000 edition).

<Measurement of phase difference characteristics>
The retardation characteristic of the optical compensation film was measured using light with a wavelength of 589 nm using a sample tilt type automatic birefringence meter (manufactured by Oji Scientific Instruments, trade name: KOBRA-WR).

<Measurement of wavelength dispersion characteristics>
As a ratio of retardation Re (450) by light of wavelength 450 nm and retardation Re (550) by light of wavelength 550 nm using a sample inclination type automatic birefringence meter (manufactured by Oji Scientific Instruments, trade name: KOBRA-WR) The wavelength dispersion characteristics of the optical compensation film were measured.

<Evaluation of stability of phase difference>
The prepared optical compensation film was heat-treated at 90 ° C. for 24 hours, and then the stability of the retardation was evaluated by the ratio (retention ratio) of the out-of-plane retardation before and after the heat treatment represented by the following formula (3).

Retention rate = Rth ₂ / Rth ₁ x 100 (3)
(Here, Rth ₁ represents the out-of-plane retardation before heat treatment, and Rth ₂ represents the out-of-plane retardation after heat treatment.)
Synthesis example 1
In a 1-liter reactor equipped with a stirrer, a condenser, a nitrogen inlet, and a thermometer, 600 g of distilled water, 3.4 g of a dispersant, hydroxypropyl methylcellulose (Shin-Etsu Chemical, trade name Metros 60 SH-50), diisopropyl fumarate 400.0 g and 8.3 g of t-butyl peroxypivalate, which is an oil-soluble radical initiator, are charged, and nitrogen bubbling is performed for 1 hour, and then radical suspension is performed by maintaining at 50 ° C. for 24 hours while stirring at 400 rpm. The polymerization was carried out. After completion of the polymerization reaction, the contents were recovered from the reactor, the polymer was separated by filtration, washed twice with distilled water and twice with methanol, and then dried under reduced pressure at 80 ° C. (yield: 77%).

  The number average molecular weight of the obtained fumaric acid ester-based polymer resin was 129,000.

Synthesis example 2
In a 1-liter reactor equipped with a stirrer, a condenser, a nitrogen inlet, and a thermometer, 600 g of distilled water, 3.4 g of a dispersant, hydroxypropyl methylcellulose (Shin-Etsu Chemical, trade name Metros 60 SH-50), diisopropyl fumarate Add 350.9 g of diethyl fumarate 49.1 g (14.0 parts by weight with respect to 100 parts by weight of diisopropyl fumarate) and 8.3 g of an oil-soluble radical initiator, t-butyl peroxypivalate, and boil with nitrogen After 1 hour, radical suspension polymerization was performed by maintaining at 50 ° C. for 28 hours while stirring at 400 rpm. After completion of the polymerization reaction, the contents were recovered from the reactor, the polymer was separated by filtration, washed twice with distilled water and twice with methanol, and then dried under reduced pressure at 80 ° C. (yield: 75%).

The number average molecular weight of the obtained fumaric acid ester-based polymer resin was 138,000. ^{According to 1} H-NMR measurement, the polymer particles are a fumaric acid diisopropyl residue unit / diethyl fumarate residue unit = 86.7 / 13.3 (mol%), that is a diisopropyl fumarate / diethyl fumarate copolymer It was confirmed.

Synthesis example 3
In a 1-liter reactor equipped with a stirrer, a condenser, a nitrogen inlet, and a thermometer, 600 g of distilled water, 3.4 g of a dispersant, hydroxypropyl methylcellulose (Shin-Etsu Chemical, trade name Metros 60 SH-50), diisopropyl fumarate 340.5 g, 59.5 g of di-n-butyl fumarate (17.6 parts by weight with respect to 100 parts by weight of diisopropyl fumarate) and 8.3 g of t-butyl peroxypivalate as an oil-soluble radical initiator After nitrogen bubbling was performed for 1 hour, radical suspension polymerization was performed by maintaining at 50 ° C. for 28 hours while stirring at 400 rpm. After completion of the polymerization reaction, the contents were recovered from the reactor, the polymer was separated by filtration, washed twice with distilled water and twice with methanol, and then dried under reduced pressure at 80 ° C. (yield: 76%).

The number average molecular weight of the obtained fumaric acid ester-based polymer resin was 117,000. ^{According to 1} H-NMR measurement, the polymer particle is a fumaric acid diisopropyl residue unit / fumaric acid di-n-butyl residue unit = 88.5 / 11.5 (mol%) diisopropyl fumaric acid / fumaric acid di-n -It confirmed that it was a butyl copolymer.

Synthesis example 4
In a 1-liter reactor equipped with a stirrer, a condenser, a nitrogen inlet, and a thermometer, 600 g of distilled water, 3.4 g of a dispersant, hydroxypropyl methylcellulose (Shin-Etsu Chemical, trade name Metros 60 SH-50), diisopropyl fumarate 332.2 g, 67.8 g of bis (2-ethylhexyl) fumarate (20.4 parts by weight with respect to 100 parts by weight of diisopropyl fumarate) and 8.3 g of an oil-soluble radical initiator, t-butyl peroxypivalate After charging for 1 hour with nitrogen bubbling, radical suspension polymerization was carried out by maintaining at 50 ° C. for 28 hours while stirring at 400 rpm. After completion of the polymerization reaction, the contents were recovered from the reactor, the polymer was separated by filtration, washed twice with distilled water and twice with methanol, and then dried under reduced pressure at 80 ° C. (yield: 73%).

The number average molecular weight of the obtained fumaric acid ester-based polymer resin was 140,000. ^{According to 1} H-NMR measurement, the polymer particle is a fumaric acid diisopropyl residue unit / bis (2-ethylhexyl) fumaric acid residue unit = 87.4 / 12.6 (mol%) It was confirmed to be a 2-ethylhexyl) copolymer.

Synthesis example 5
In a 1-liter reactor equipped with a stirrer, a condenser, a nitrogen inlet, and a thermometer, 600 g of distilled water, 3.4 g of a dispersant, hydroxypropyl methylcellulose (Shin-Etsu Chemical, trade name Metros 60 SH-50), diisopropyl fumarate 350.9 g, 27.8 parts by weight of di-n-octyl fumarate (20.4 parts by weight with respect to 100 parts by weight of diisopropyl fumarate) and 8.3 g of an oil-soluble radical initiator, t-butyl peroxypivalate After nitrogen bubbling was performed for 1 hour, radical suspension polymerization was performed by maintaining at 50 ° C. for 28 hours while stirring at 400 rpm. After completion of the polymerization reaction, the contents were recovered from the reactor, the polymer was separated by filtration, washed twice with distilled water and twice with methanol, and then dried under reduced pressure at 80 ° C. (yield: 77%).

The number average molecular weight of the obtained fumaric acid ester-based polymer resin was 125,000. ^{According to 1} H-NMR measurement, the polymer particle is a fumaric acid diisopropyl residue unit / fumaric acid di-n-octyl residue unit = 87.2 / 12.8 (mol%) diisopropyl fumaric acid / fumaric acid di-n It was confirmed to be an octyl copolymer.

Synthesis example 6
In a 1-liter reactor equipped with a stirrer, a condenser, a nitrogen inlet, and a thermometer, 600 g of distilled water, 3.4 g of a dispersant, hydroxypropyl methylcellulose (Shin-Etsu Chemical, trade name Metros 60 SH-50), diisopropyl fumarate 389.4 g, 10.6 g of 3-ethyl-3-oxetanyl methyl acrylate (2.7 parts by weight with respect to 100 parts by weight of diisopropyl fumarate) and t-butyl peroxypivalate which is an oil-soluble radical initiator. After 3 g was charged, nitrogen bubbling was performed for 1 hour, and radical suspension polymerization was performed by maintaining at 50 ° C. for 24 hours while stirring at 400 rpm. After completion of the polymerization reaction, the contents were recovered from the reactor, the polymer was separated by filtration, washed twice with distilled water and twice with methanol, and then dried under reduced pressure at 80 ° C. (yield: 75%).

The number average molecular weight of the obtained fumaric acid ester-based polymer resin was 109,000. ^{According to 1} H-NMR measurement, the polymer particle is diisopropyl fumarate residue unit / 3-ethyl-3-oxetanyl methyl acrylate residue unit = 96.2 / 3.8 (mol%) diisopropyl fumarate acrylic acid It was confirmed to be a 3-ethyl-3-oxetanylmethyl copolymer.

Film making example 1
The diisopropyl fumaric acid polymer obtained in Synthesis Example 1 is dissolved in a mixed solution of toluene and methyl ethyl ketone (toluene / methyl ethyl ketone = 50% by weight / 50% by weight) to make a 20% solution, and the solution casting apparatus is supported by the T-die method. The solution was cast on a substrate and dried at 80 ° C. and 130 ° C. for 4 minutes to obtain a film 250 mm wide and 50 μm thick.

Film making example 2
Diisopropyl fumarate / diethyl fumarate copolymer obtained in Synthesis Example 2 is dissolved in a mixed solution of toluene and methyl ethyl ketone (toluene / methyl ethyl ketone = 50% by weight / 50% by weight) to make a 20% solution, and the solution is obtained by T-die method. The resultant was cast on a support substrate of a casting apparatus and dried at 80 ° C. and 130 ° C. for 4 minutes to obtain a film 250 mm wide and 40 μm thick.

Film making example 3
Dissolve the diisopropyl fumarate / di-n-butyl fumarate copolymer obtained in Synthesis Example 3 in a mixed solution of toluene and methyl ethyl ketone (toluene / methyl ethyl ketone = 50% by weight / 50% by weight) to make a 20% solution, T The solution was cast on a supporting substrate of a solution casting apparatus by a die method, and dried at 80 ° C. and 130 ° C. for 4 minutes to obtain a film 250 mm wide and 45 μm thick.

Film making example 4
Dissolve the diisopropyl fumarate / bis (2-ethylhexyl) fumarate copolymer obtained in Synthesis Example 4 in a toluene / methyl ethyl ketone mixed solution (toluene / methyl ethyl ketone = 50% by weight / 50% by weight) to make a 20% solution, The solution was cast on a support substrate of a solution casting apparatus by a T-die method, and dried at 80 ° C. and 130 ° C. for 4 minutes to obtain a film 250 mm wide and 40 μm thick.

Film making example 5
Dissolve the fumaric acid diisopropyl fumaric acid di-n-octyl copolymer obtained in Synthesis Example 5 in a mixed solution of toluene and methyl ethyl ketone (toluene / methyl ethyl ketone = 50% by weight / 50% by weight) to make a 20% solution, T The solution was cast on a supporting substrate of a solution casting apparatus by a die method, and dried at 80 ° C. and 130 ° C. for 4 minutes to obtain a film 250 mm wide and 45 μm thick.

Film making example 6
A 20% solution of the diisopropyl fumaric acid-acrylic acid 3-ethyl-3-oxetanylmethyl copolymer obtained in Synthesis Example 6 dissolved in a mixed solution of toluene and methyl ethyl ketone (toluene / methyl ethyl ketone = 50% by weight / 50% by weight) The resultant was cast on a support substrate of a solution casting apparatus by a T-die method, and dried for 4 minutes each at 80 ° C. and 130 ° C. to obtain a film 250 mm wide and 45 μm thick.

Film making example 7
A polycarbonate resin (manufactured by Aldrich) is dissolved in a methylene chloride solution to make a 25% solution, cast on a support substrate of a solution casting apparatus by a T-die method, and dried at 40 ° C, 80 ° C and 120 ° C for 15 minutes, A film having a width of 250 mm and a thickness of 50 μm was obtained.

Example 1
The film obtained in Film Preparation Example 1 was cut into a square of one piece 50 mm, and a temperature of 150 ° C., a drawing speed of 10 mm / min. Biaxial stretching was performed under the following conditions, and the film was stretched 1.25 times. Further, the stretched film was kept at 150 ° C. for 5 minutes while being fixed, and the obtained optical compensation film was removed from the stretching apparatus. From the results of three-dimensional refractive index measurement of the optical compensation film (nx = 1.4701, ny = 1.4702, nz = 1.4755), the obtained optical compensation film has nx ≦ ny <nz and the thickness direction of the film The refractive index was large. In-plane retardation Re = (ny−nx) × d is 3.8 nm, out-of-plane retardation Rth = [(nx + ny) / 2−nz] × d is −201 nm, retardation ratio (R450 / R550) (wavelength The dependence (dependency) was 1.01, the retention of out-of-plane retardation was 99.0%, and the stability of retardation was excellent.

  From these results, the obtained optical compensation film has negative birefringence, a large refractive index in the thickness direction, small wavelength dependency, and excellent stability of retardation, so it is suitable for an optical compensation film It was a thing.

Example 2
The film obtained in Film Preparation Example 2 was cut into a square of one piece 50 mm, and a temperature of 150 ° C., a drawing speed of 10 mm / min. Biaxial stretching was performed under the following conditions, and the film was stretched 1.25 times. Further, the stretched film was kept at 150 ° C. for 5 minutes while being fixed, and the obtained optical compensation film was removed from the stretching apparatus. From the results of three-dimensional refractive index measurement of the optical compensation film (nx = 1.4698, ny = 1.4699, nz = 1.4756), the obtained optical compensation film has nx ≦ ny <nz and the thickness direction of the film The refractive index was large. In-plane retardation Re = (ny−nx) × d is 3.7 nm, out-of-plane retardation Rth = [(nx + ny) / 2−nz] × d is −213 nm, retardation ratio (R450 / R550) (wavelength The dependence (dependency) was 1.02, the retention of out-of-plane retardation was 99.1%, and the stability of retardation was excellent.

  From these results, the obtained optical compensation film has negative birefringence, a large refractive index in the thickness direction, small wavelength dependency, and excellent stability of retardation, so it is suitable for an optical compensation film It was a thing.

Example 3
The film obtained in Film Preparation Example 3 was cut into a square of one piece 50 mm, and a temperature of 140 ° C., a drawing speed of 10 mm / min. Biaxial stretching was performed under the following conditions, and the film was stretched 1.25 times. Further, the stretched film was kept at 150 ° C. for 5 minutes while being fixed, and the obtained optical compensation film was removed from the stretching apparatus. From the results of three-dimensional refractive index measurement of the optical compensation film (nx = 1.4699, ny = 1.4700, nz = 1.4761), the obtained optical compensation film has nx ≦ ny <nz and the thickness direction of the film The refractive index was large. In-plane retardation Re = (ny−nx) × d is 3.3 nm, out-of-plane retardation Rth = [(nx + ny) / 2−nz] × d is −200 nm, retardation ratio (R450 / R550) (wavelength The dependence (dependency) was 1.01, the retention of out-of-plane retardation was 99.3%, and the stability of retardation was excellent.

  From these results, the obtained optical compensation film has negative birefringence, a large refractive index in the thickness direction, small wavelength dependency, and excellent stability of retardation, so it is suitable for an optical compensation film It was a thing.

Example 4
The film obtained in Film Preparation Example 4 was cut into a square of one piece 50 mm, and a temperature of 150 ° C., a drawing speed of 10 mm / min. Biaxial stretching was performed under the following conditions, and the film was stretched 1.25 times. Further, the stretched film was fixed while being heated and held at 150 ° C. for 10 minutes, and the obtained optical compensation film was removed from the stretching apparatus. From the results of three-dimensional refractive index measurement of the optical compensation film (nx = 1.4695, ny = 1.4696, nz = 1.4752), the obtained optical compensation film has nx ≦ ny <nz and the thickness direction of the film The refractive index was large. In-plane retardation Re = (ny−nx) × d is 3.5 nm, out-of-plane retardation Rth = [(nx + ny) / 2−nz] × d is −197 nm, retardation ratio (R450 / R550) (wavelength The dependence (dependency) was 1.01, the retention of out-of-plane retardation was 99.1%, and the stability of retardation was excellent.

  From these results, the obtained optical compensation film has negative birefringence, a large refractive index in the thickness direction, small wavelength dependency, and excellent stability of retardation, so it is suitable for an optical compensation film It was a thing.

Example 5
The film obtained in Film Preparation Example 5 is cut into a square of one piece 50 mm, and a temperature of 140 ° C., a drawing speed of 10 mm / min. Biaxial stretching was performed under the following conditions, and the film was stretched 1.25 times. Further, the stretched film was fixed while being heated and held at 150 ° C. for 10 minutes, and the obtained optical compensation film was removed from the stretching apparatus. From the results of three-dimensional refractive index measurement of the optical compensation film (nx = 1.4685, ny = 1.4687, nz = 1.4749), the obtained optical compensation film has nx ≦ ny <nz and the thickness direction of the film The refractive index was large. In-plane retardation Re = (ny−nx) × d is 7.3 nm, out-of-plane retardation Rth = [(nx + ny) / 2−nz] × d is −229 nm, retardation ratio (R450 / R550) (wavelength The dependence (dependency) was 1.02, the retention of out-of-plane retardation was 99.2%, and the stability of retardation was excellent.

  From these results, the obtained optical compensation film has negative birefringence, a large refractive index in the thickness direction, small wavelength dependency, and excellent stability of retardation, so it is suitable for an optical compensation film It was a thing.

Example 6
The film obtained in Film Preparation Example 6 was cut into a square of one piece 50 mm, and a temperature of 150 ° C. and a drawing speed of 10 mm / min. Biaxial stretching was performed under the following conditions, and the film was stretched 1.25 times. Further, the stretched film was fixed while being heated and held at 150 ° C. for 10 minutes, and the obtained optical compensation film was removed from the stretching apparatus. From the results of three-dimensional refractive index measurement of the optical compensation film (nx = 1.4686, ny = 1.4687, nz = 1.4748), the obtained optical compensation film has nx ≦ ny <nz and the thickness direction of the film The refractive index was large. In-plane retardation Re = (ny−nx) × d is 3.6 nm, out-of-plane retardation Rth = [(nx + ny) / 2−nz] × d is −221 nm, retardation ratio (R450 / R550) (wavelength The dependence (dependency) was 1.01, the retention of out-of-plane retardation was 99.1%, and the stability of retardation was excellent.

  From these results, the obtained optical compensation film has negative birefringence, a large refractive index in the thickness direction, small wavelength dependency, and excellent stability of retardation, so it is suitable for an optical compensation film It was a thing.

Comparative Example 1
The film obtained in Film Preparation Example 1 was cut into a square of one piece 50 mm, and a temperature of 150 ° C., a drawing speed of 10 mm / min. The film was biaxially stretched under the following conditions and stretched 1.25 times, and the film was immediately taken out of the stretching apparatus. From the results of three-dimensional refractive index measurement of the film (nx = 1.4701, ny = 1.4703, nz = 1.4756), the obtained film has a refractive index of nx ≦ ny <nz and a thickness direction of the film It was great. In-plane retardation Re = (ny−nx) × d is 7.5 nm, out-of-plane retardation Rth = [(nx + ny) / 2−nz] × d is −202 nm, retardation ratio (R450 / R550) (wavelength The dependence was 1.01 and the retention of out-of-plane retardation was 88.0%, which was inferior to the stability of retardation.

  From these results, the film obtained by stretching had a problem in the stability of retardation because it was not subjected to the heat treatment after stretching.

Comparative example 2
The film obtained in Film Preparation Example 7 was cut into a square of one piece 50 mm, and a temperature of 150 ° C., a drawing speed of 10 mm / min. The film was biaxially stretched under the following conditions and stretched 1.25 times, and the film was immediately taken out of the stretching apparatus. From the results of three-dimensional refractive index measurement of the film (nx = 1.5855, ny = 1.5859, nz = 1.5832), the obtained film has a refractive index in the in-plane direction of the film of nz <nx ny. Was great. In-plane retardation Re = (ny−nx) × d is 16.4 nm, out-of-plane retardation Rth = [(nx + ny) / 2−nz] × d is 103 nm, retardation ratio (R450 / R550) (wavelength dependent) Sex) was 1.18.

  From these results, the film obtained by stretching was not suitable for the optical compensation film of the viewing angle compensation performance of the IPS-LCD because the fumaric acid ester polymer resin was not used.

Claims (5)

  After the film containing the fumaric acid ester polymer resin is stretched uniaxially at 50 ° C. to 200 ° C., the stretched film is continuously heated and held at 100 ° C. to 200 ° C. for 1 minute to 15 minutes while being fixed. An optical compensation film is obtained, The manufacturing method of the optical compensation film characterized by the above-mentioned. The method for producing an optical compensation film according to claim 1, wherein the fumaric acid ester-based polymer resin contains 30 mol% or more of fumaric acid ester residue units represented by the following general formula (1).

(Wherein, R ₁ and R ₂ each independently represent an alkyl group having 1 to 12 carbon atoms) The fumaric acid ester-based polymer resin comprises: fumaric acid diisopropyl residue, fumaric acid diethyl residue, fumaric acid di-n-propyl residue, fumaric acid di-n-butyl residue, fumaric acid di-2-ethylhexyl residue The method for producing an optical compensation film according to claim 1 or 2, comprising a fumaric acid ester residue unit selected from When the refractive index in the fast axis direction in the film plane is nx, the refractive index in the vertical direction is ny, and the refractive index in the thickness direction of the film is nz, there is a relationship of nx ≦ ny <nz and a wavelength of 450 nm 4. The optical compensation film according to claim 1, wherein a ratio (R450 / R550) of the retardation measured with light to the retardation measured with light of wavelength 550 nm is 1.1 or less. The manufacturing method of the optical compensation film as described in-. The in-plane retardation (Re) measured at a wavelength of 550 nm represented by the following formula (1) is 0 to 300 nm, and the out-of-plane retardation (Rth) represented by the following formula (2) is -30 to -300 nm An optical compensation film is obtained, The manufacturing method of the optical compensation film in any one of the Claims 1-4 characterized by the above-mentioned.
Re = (ny-nx) x d (1)
Rth = [(nx + ny) / 2-nz] × d (2)
(Wherein, nx represents the refractive index in the fast axis direction in the film plane, ny represents the refractive index in the film plane slow axis direction, nz represents the refractive index out of the film plane, and d represents the film Indicates the thickness)

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