KR20070115897A - Retardation film made by using cellulose derivative - Google Patents

Abstract

A retardation film having biaxial or achromatic properties, which is produced by uniaxially stretching a film made of either a cellulose derivative wherein hydroxyl groups are replaced by acyl having 5 to 20 carbon atoms, preferably 7 to 20 carbon atoms, still preferably 8 to 20 carbon atoms or a product of crosslinking of the cellulose derivative. The retardation film exhibits negative birefringence and excellent optical characteristics, can be easily produced by uniaxial stretching, and is improved in heat resistance or tear strength which conventional cellulose ester films are problematic in.

Description

Retardation film using a cellulose derivative {RETARDATION FILM MADE BY USING CELLULOSE DERIVATIVE}

The present invention relates to a retardation film using a cellulose derivative useful for an image display device such as a liquid crystal display device, an optical film using the same, and a liquid crystal display device having excellent viewing angle characteristics by using these films.

As a display device, CRT (Cathode Ray Tube) has been mainly used until now, but recently, liquid crystal display devices have been widely used in various environments in PC monitors, TVs, mobile phones, and automobile monitors. In addition, high contrast, wide viewing angle characteristics, and high durability are required as the performance of the display device.

In a conventional liquid crystal display device, a retardation film is used in addition to a liquid crystal cell and a polarizing plate. In a liquid crystal display device, even if a liquid crystal material having an anisotropy and a polarizing plate can obtain a good display when viewed from the front, there is a problem of viewing angle dependence that the display performance deteriorates when viewed from the side, and a retardation film is used for the improvement.

The retardation film has a function of converting linearly polarized light into elliptical polarization or circularly polarized light, or converting linearly polarized light in a certain direction to another direction (linearly polarized light), and by using these functions, for example, liquid crystal The viewing angle, contrast and the like of the display device can be improved. This retardation film is usually obtained by uniaxially or biaxially stretching a plastic film such as polycarbonate, polyarylate, polyethersulfone or the like. At this time, birefringence arises by the anisotropy of the refractive index which arises by extending | stretching, and functions as a retardation film. The optical performance of the retardation film is, for example, the refractive index of the phase retardation axis direction (the direction in which the refractive index becomes maximum in the plane) in the phase retardation film front direction at a certain wavelength and the direction of the retardation axis of the retardation film (in-plane retardation direction). It can be determined by the retardation value computed by the product of the difference of the refractive index of the direction to), and the thickness of retardation film. However, these retardation values include so-called wavelength dependence (wavelength dispersion characteristic) and viewing angle dependence (viewing angle characteristic), and the retardation film is used in various kinds of displays in consideration of the comprehensive performance including these various characteristics.

The wavelength dispersion characteristic varies depending on the material used as the wavelength dependence of the phase difference value. For example, a phase difference value on the long wavelength side of the retardation film made of a plastic film such as polycarbonate, polyarylate, polyethersulfone, or the like is higher than 550 nm. It is smaller than the phase difference value in 550 nm, and the phase difference value on the short wavelength side is larger than the phase difference value in 550 nm than 550 nm.

Therefore, even if the retardation value at 550 nm is set to 137.5 nm in order to produce a 1/4 wavelength retardation film, the retardation on the longer wavelength side than 550 nm becomes 1/4 or less of the wavelength and is shorter than 550 nm. The phase difference on the side becomes 1/4 or more of the wavelength.

This is, for example, when the antireflection filter is produced using a retardation film (so-called quarter wave plate) such that the retardation becomes 1/4 of the wavelength, the antireflection effect is sufficiently obtained. Only in the wavelength range such as 1/4, circular polarization becomes elliptical polarization at other wavelengths, resulting in a problem that a sufficient antireflection effect cannot be obtained. In addition, when a linear light polarizer which can be used for a liquid crystal projector or the like is produced using a retardation film (so-called 1/2 wave plate) whose retardation is 1/2 of a wavelength, linearly polarized light is converted into linearly polarized light. Only the wavelength range where the phase difference becomes almost 1/2 can be rotated. In other wavelengths, linearly polarized light becomes elliptical polarization, and sufficient optical beneficiation effect cannot be obtained.

A retardation film having wavelength dispersion characteristics such as giving an equal retardation with respect to the wavelength over the entire visible region is called an achromatic retardation film, and in order to exhibit such a tendency (chromaticity), for example, a retardation at a wavelength of 550 nm. The phase difference value on the long wavelength side is larger than the value, and the phase difference value on the short wavelength side is smaller than the phase difference value at the wavelength of 550 nm. As a method of manufacturing such a retardation film, as described in patent document 1, the method of laminating | stacking a some stretched film by crossing those optical axes is proposed. Moreover, as described in patent document 2, by using the cellulose acetate obtained by the hydrolysis of a cellulose triacetate as a polymer for manufacturing retardation film, it is the same in each wavelength in a wide range with one film. The retardation film which can provide the retardation of the grade is proposed.

On the other hand, the viewing angle characteristic is the angle dependence of the retardation value, and is generally controlled by the stretching method of the retardation film. The stretching causes the refractive index nx in the stretching direction, the refractive index ny in the direction orthogonal to the film plane, and the thickness direction refractive index nz, and the value determines the viewing angle characteristic of the retardation film. In uniaxial stretching, since it usually becomes a relationship of nx> ny = nz, it becomes a retardation film which has what is called uniaxiality. On the other hand, the biaxiality may be, for example, nx> ny = nz or nz≥ny> nx or ny> nz> nx. However, in the case of normal uniaxial stretching, it is not easy to obtain a retardation film having such a refractive index. not.

For example, in the case of a general retardation film obtained by uniaxially stretching a polymer film such as polycarbonate, in the case of inclining in the phase retardation axis direction, the larger the inclination angle from the front direction, the smaller the retardation value, and conversely the phase progression. In the case of inclining in the axial direction, the larger the inclination angle from the front direction, the larger the phase difference value. This tendency is commonly seen in general retardation films other than uniaxial stretching, such as polyarylates, polyethersulfones, cycloolefin-based polymers such as Zeonoa (manufactured by Nihon Xion) and Aton (manufactured by JSR). to be. In the use of the retardation film, there are cases where the characteristics of retardation values change with the inclination and the characteristics with little change in the retardation values due to the inclination may be used. Which of the characteristics of the retardation film is used depends on the purpose. It is classified appropriately.

As a phase difference film which suppressed the change of the phase difference value according to inclination as much as possible, patent document 3 adhere | attaches a shrinkable film to the film stretched, and uniaxially stretches this, and performs biaxial stretching substantially, and retardation value according to inclination The manufacturing method of the retardation film which suppressed the change of is disclosed.

Moreover, patent document 4, 5 has description regarding the retardation film which has the negative refractive index anisotropy excellent in heat resistance for the purpose of improving the viewing angle characteristic of a liquid crystal display device.

Further, Patent Document 6 discloses a viewing angle and the like by using an optically biaxial film obtained by stretching a cellulose ester, specifically, a cellulose acetate or a cellulose acetate having both an acetyl group and a propionyl group or a butyryl group. There is a description that an improved liquid crystal display device can be provided. However, in this method, the film strength is sometimes lowered by the stretching operation.

Therefore, as an improvement of the film strength of a cellulose derivative, in patent document 7, a film is produced from the composition containing a cellulose acrelite, specifically, a cellulose triacetate, a polymerizable monomer, and a polymerization initiator, and tear strength and abrasion resistance There is a substrate that improves the figure.

Patent Document 8 discloses a retardation plate composed of a polymer film having a retardation value and a refractive index each satisfying a specific formula, and containing a cellulose ester as a polymer, and specifically, a retardation plate made of a cellulose acetate film is disclosed. have. In Patent Document 9, after the remaining hydroxy group of the cellulose ester, specifically cellulose acetate propionate, forms a crosslinked structure through a covalent bond, and reacted with a crosslinking agent having at least one aromatic ring in the crosslinked portion, The optical film obtained by extending | stretching is described and it is described to improve film | membrane properties, such as an elasticity modulus and dimensional stability.

Patent Document 1: Patent No.3174367

Patent Document 2: Patent No. 3459779

Patent Document 3: Patent No. 2818983

Patent Document 4: Japanese Unexamined Patent Publication 2001-194530

Patent Document 5: Japanese Unexamined Patent Publication 2004-309617

Patent Document 6: Japanese Unexamined Patent Publication 2002-187960

Patent Document 7: Japanese Unexamined Patent Publication 2004-176025

Patent Document 8: Japanese Unexamined Patent Publication 2002-131539

Patent Document 9: Japanese Unexamined Patent Publication 2004-244497

Challenges the invention seeks to solve

Desired wavelength dispersion characteristics and birefringence vary depending on the intended use. However, until now, in order to obtain desired wavelength dispersion characteristics, a retardation film having a main chain portion, which is a basic structure of a polymer, having a completely different polymer has to be used. This requires that a polymer be synthesized from the main chain portion for each material having a different wavelength dispersion, and depending on the structure, the synthesis and molecular weight control may be very difficult. Therefore, there is a problem that the wavelength dispersion cannot be arbitrarily selected. In addition, although birefringence is positive birefringence and negative birefringence, although the magnitude of the absolute value of birefringence can be controlled by processing conditions, positive and negative control cannot be achieved unless the basic structure of the polymer used is changed. Moreover, the retardation film using what is called cellulose acetate as described in patent document 2, for example, had a problem that birefringence is inadequate. For this reason, when obtaining the retardation value required as a quarter wavelength retardation film, for example, thickness must be thickened, and it could not fully respond to the request to thinning. Moreover, the change of the retardation value at the time of making the retardation film incline from a front direction, and the viewing angle characteristic of what is called a retardation film also was not necessarily good.

On the other hand, the control of the viewing angle characteristics has been achieved only by the stretching method so far, but in the method of bonding the shrinkable film as described in Patent Document 3 and performing substantial biaxial stretching, the shrinkage film is adhered or peeled after stretching. The increase of the process called, generate | occur | produced the problem of cost increase by it.

Moreover, in order to improve the heat resistance of a film, although patent document 4 describes using retardation film using the polycarbonate-type resin which has a fluorene frame | skeleton, although these films have heat resistance, they are used in combination with a polarizing film In this case, the polarizing film and the adhesive have to be adhered to each other, so that not only the adhesion step is increased but also the thickness of the laminate becomes thick.

The retardation film which consists of cellulose esters has the problem that heat resistance is generally low compared with polycarbonate and polyolefin. Therefore, as shown in Patent Literature 8, improvements such as adding a compound having two or more aromatic rings to the doping solution have been made, but in order to contain a compound having two or more aromatic rings, there have been problems such as coloring. .

Moreover, when using the crosslinking agent which has an aromatic ring like patent document 9, there exists a problem that coloring of a film arises.

In general, since an optical film made of a cellulose derivative has a low film strength compared to that of an optical film made of another material such as cycloolefin polymer or polycarbonate, the film strength of the optical film made of a cellulose derivative is added. Improvement is desired.

Means to solve the problem

MEANS TO SOLVE THE PROBLEM As a result of earnestly researching in order to solve the said subject, the present inventors discovered that the retardation film produced from the cellulose derivative which has a specific physical property solved the said subject, and completed this invention. (1) nx> ny> nz or nz≥ny> nx or ny> nz> nx where the hydroxyl group of cellulose consists of uniaxial stretching of the film which consists of cellulose derivatives substituted by the acyl group of 5-20 carbon atoms (stretching direction) The use of a retardation film having a refractive index of nx, a refractive index in a direction perpendicular to the plane thereof, and a refractive index of ny and a thickness in the thickness direction is zn) has found that problems such as wavelength dispersion characteristics and viewing angle characteristics can be solved. That is, by changing the structure and the degree of substitution of the substituent of the cellulose, the wavelength dispersion characteristics and the birefringence of the positive and negative can be arbitrarily controlled, and the film having a high birefringence can be obtained by the selection of this cellulose derivative. By the selection of this cellulose derivative, the retardation film which expresses biaxiality only by uniaxial stretching and controls the viewing angle characteristic, without performing substantially biaxial stretching like what is described in patent document 3 is carried out by the selection of this cellulose derivative. It was found that it can be obtained. (2) The heat resistance of a film is a retardation film in which a hydroxyl group is substituted by an aliphatic acyl group having 8 to 20 carbon atoms, and the substitution degree of the hydroxyl group is obtained by stretching a cellulose derivative having a substitution degree of 1.0 to less than 2.9 per cellulose monomer unit. It was found to be improving. That is, by optimizing the substitution degree of the substituent of this cellulose, biaxial stretching is expressed only by uniaxial stretching, without performing substantially biaxial stretching as described in patent document 3, and also controlling a viewing angle characteristic, Alkali treatment of the surface layer enables direct adhesion with the polarizing element as a support of the polarizing film, and also has a heat resistance capable of maintaining the shape of the film even at 110 ° C. or higher, and obtains a retardation film having negative refractive index anisotropy. It was found that it can. (3) The hydroxyl group is substituted by an aliphatic acyl group having 7 to 20 carbon atoms, preferably 8 to 20 carbon atoms, and the hydroxyl group has a degree of substitution of 1.0 to less than 2.9 per monomer unit of cellulose. And the retardation film formed by extending | stretching the cellulose derivative bridge | crosslinked with the compound which has at least 1 or more functional group which can react, and which has a crosslinkable functional group, was found to be able to improve tearing strength. In other words, it was found that a highly transparent film having excellent optical properties and negative birefringence with improved tear strength could be obtained.

That is, the present invention,

(1) nx> ny> nz or nz≥ny> nx or ny> nz> nx (refractive index of extending | stretching direction) formed by uniaxially stretching the film which consists of a cellulose derivative substituted by the acyl group of 5-20 carbon atoms of cellulose This nx, the retardation film whose refractive index in the direction orthogonal to it is ny, and the refractive index of the thickness direction is zn),

(2) nx> ny> nz (refractive index of extending | stretching direction) formed by uniaxially stretching the film which consists of a cellulose derivative of 2.0-2.8 substitution degree by which the hydroxyl group of cellulose was substituted by n-pentanoyl group in said (1). A phase difference film having nx, a refractive index in the direction orthogonal to it in the plane, and a refractive index in the thickness direction, zn), and a wavelength dispersion characteristic having an achromatic property,

(3) nx> ny> nz (refractive index of extending | stretching direction) formed by uniaxially stretching the film which consists of a cellulose derivative of 2.0-2.5 substitution degree by which the hydroxyl group of cellulose was substituted by n-hexanoyl group in said (1). A phase difference film having nx, a refractive index in the direction orthogonal to it in the plane, and a refractive index in the thickness direction, zn), and a wavelength dispersion characteristic having an achromatic property,

(4) In the above (1), nz ≧ ny> nx or ny> nz> nx where hydroxy group of cellulose formed by uniaxial stretching of the film which consists of a cellulose derivative substituted by the C7-C20 linear acyl group of the cellulose group The refractive index in the stretching direction is nx, the refractive index in the direction orthogonal to it is ny, the refractive index in the thickness direction is zn), and the phase difference value at the wavelength difference of 550 nm is longer than the wavelength dispersion characteristic at 550 nm. A phase difference film smaller than and smaller than the phase difference value at 550 nm on the shorter wavelength side,

(5) The retardation film of the said (4) whose substitution degree of the C7 straight-chain acyl group is 2.7-3.0,

(6) The phase difference film as described in said (4) whose substitution degree of the C8-C20 linear acyl group is 2.0-3.0.

(7) The aliphatic acyl group in any one of said (1)-(5), and this acyl group contains a substituent different from each other, The substitution degree of the C5-C20 aliphatic acyl group is 2.00 or more, and the number of other substituents Ny> nz> nx or nz≥ny> nx formed by uniaxial stretching of the film which consists of a cellulose derivative whose sum total is 2.50-3.0 per cellulose monomer unit (ny> nz> nx or nz≥ny> nx (refractive index of extending | stretching direction is nx, and direction orthogonal to it in-plane) A retardation film having a refractive index of ny and a refractive index of zn) in the thickness direction,

(8) The aliphatic acyl group having 8 to 20 carbon atoms as described in (1) above, wherein the three-dimensional refractive index at the measurement wavelength of 590 nm satisfies the following formula (1), and the heat resistance is 110 ° C or higher. A phase difference film formed by stretching a cellulose derivative having a degree of substitution of hydroxyl groups of 1.0 or more and less than 2.9 per cellulose 1 monomer unit,

ny> nx (1)

In said formula (1), nx is the refractive index of the extending direction in retardation film surface, and ny is the refractive index of the extending direction and orthogonal direction in retardation film surface.

(9) The retardation film formed by extending | stretching the cellulose derivative bridge | crosslinked by the aliphatic compound which has at least 1 or more functional group which can react with the remaining hydroxyl group of a cellulose derivative, and has a crosslinkable functional group,

(10) The retardation film according to the above (8) or (9), wherein the retardation ratio of the retardation film measured at a measurement wavelength of 590 nm satisfies the following formula (2),

0.5≤R (50) / R (0) ≤1.1 (2)

In the formula (2), R (50) is a retardation value when the retardation film is viewed in the direction inclined 50 ° in the phase advancing axis direction from the front, and R (0) is a retardation value when the retardation film is viewed from the front. to be.

(11) The composite retardation film which laminated | stacked the retardation film as described in any one of said (1)-(10), and another retardation film,

(12) a circle or elliptical polarizing film or optical film formed by laminating the retardation film or composite retardation film according to any one of (1) to (10) and a polarizing film,

(13) An optical film formed by laminating so that the phase retardation axis of the retardation film as described in any one of said (1)-(10), and the absorption axis or transmission axis of a polarizing film become parallel or orthogonal,

(14) When the average refractive index in the film plane is no and the refractive index in the thickness direction is ne, when ne-no <0 and the thickness is d, Rth calculated from Rth = (no-ne) × d is 100 to The film whose phase difference value in the film front direction in 300 nm and 550 nm is 0-50 nm, the retardation film of any one of Claims 1-10, and a polarizing film are laminated one by one, and the retardation film A composite optical film laminated such that the phase retardation axis of the polarization element and the absorption axis of the polarizer are orthogonal to each other,

(15) The circle according to any one of (11) to (14), wherein the polarizing element constituting the polarizing film and the retardation film according to any one of the above (1) to (10) are laminated directly. Or elliptical polarizing film or optical film or optical film or composite optical film,

(16) An image display device comprising the circle or elliptical polarizing film or optical film or optical film or composite optical film according to any one of (11) to (14) above.

(17) The image display apparatus according to (16), wherein the image display apparatus is a liquid crystal display apparatus;

(18) The remainder of the cellulose ester in which the three-dimensional refractive index at the measured wavelength 590 nm satisfies the following formula (1), and the degree of substitution of the hydroxyl group by the aliphatic acyl group having 7 to 20 carbon atoms is 1.0 or more and less than 2.9 per cellulose monomer. A retardation film having at least one functional group capable of reacting with a hydroxyl group of and stretching the cellulose derivative crosslinked with an aliphatic compound having a crosslinkable functional group,

ny> nx (1)

In said Formula (1), nx is the refractive index of the extending direction in retardation film surface, and ny is the refractive index of the extending direction and orthogonal direction in retardation film surface.

(19) The retardation film of the above (18), wherein the retardation ratio of this retardation film measured at a measurement wavelength of 590 nm satisfies the following formula (2),

0.5 ≤ R (50) / R (0) ≤ 1.1 (2)

In the above formula (2), R (50) is a retardation value when the retardation film is viewed in a direction inclined 50 ° in the phase advancing axis direction from the front, and R (0) is a retardation value when the retardation film is viewed from the front. to be.

(20) The retardation film according to the above (18), wherein the tear strength is 400 kg / cm 2 or more.

(21) The composite retardation film which laminated | stacked the retardation film and other retardation film as described in said (18),

(22) Optical film which laminated | stacked the polarizing film on the retardation film as described in said (18), or the composite retardation film which laminated | stacked this retardation film and another retardation film,

(23) A liquid crystal display device comprising the retardation film, the composite retardation film, or the optical film according to any one of (18) to (22) above.

(24) In the above (18), the cellulose derivative crosslinked with an aliphatic compound having a crosslinkable functional group reacts an isocyanate group of an aliphatic compound having an isocyanate group with a (meth) acryloyl group to react with the remaining hydroxyl group of the cellulose ester Retardation film which is a cellulose derivative which bridge | crosslinked the obtained compound by the superposition | polymerization of a (meth) acryloyl group,

(25) The retardation film according to the above (24), wherein the aliphatic compound having an isocyanate group and a (meth) acryloyl group is (meth) acryloyloxy C1-C20 aliphatic hydrocarbon isocyanate,

(26) Cellulose obtained by reacting a (meth) acryloyloxy C1-C20 aliphatic hydrocarbon isocyanate with a cellulose ester having a degree of substitution of a hydroxyl group by an aliphatic acyl group having 7 to 20 carbon atoms per unit of cellulose of 1.0 or more and less than 2.9. It relates to an ester.

Effects of the Invention

By producing a retardation film using the cellulose derivative of this invention and the resin composition containing this, wavelength dispersion, birefringence positive and negative, and viewing angle characteristics can be controlled. In addition, it is excellent in transparency and can improve heat resistance or tear strength. Moreover, depending on the cellulose derivative to be used, in order to have sufficient birefringence, thickness can be made thin. In addition, the retardation film of the present invention is an antireflection film such as a viewing angle improvement film of a transmissive liquid crystal display device, a quarter-wave retardation film constituting a reflective and semi-transmissive liquid crystal display device, a specular reflection prevention film of a touch panel, and VA ( Vertical alignment: Visual compensation film such as compensation film used in vertical alignment) or IPS (In-Plan Switching) mode liquid crystal display device, Optical efficiency enhancing film such as wavelength plate for polarizing beam splitter of liquid crystal projector, Lighting of optical disk It can be used for the simultaneous compensation film of one wavelength or two or more wavelengths, such as a wave plate used for pickup. The retardation film of the present invention can be used in an organic EL display device, a liquid crystal projector, a liquid crystal display device as a circular polarizing film, a polarizing film, an elliptical polarizing film, an optical film, or a composite optical film in combination with a polarizing film. The image display device according to the present invention can be provided with excellent characteristics such that contrast and viewing angle characteristics are improved as compared with the conventional image display device.

1 is a graph showing wavelength dispersion characteristics of the retardation film of the present invention produced in Examples 1, 2, 4, 6, 7 and Comparative Example 7.

It is a graph which shows the viewing angle characteristic of the retardation film used in Examples 12-14 and 18.

Explanation of the sign

1

The wavelength dispersion curve of the retardation film produced in Example 1 is shown.

The wavelength dispersion curve of the retardation film produced in Example 2 is shown.

□ The wavelength dispersion curve of the retardation film produced in Example 4 is shown.

The wavelength dispersion curve of the retardation film produced in Example 6 is shown.

* The wavelength dispersion curve of the retardation film produced in Example 7 is shown.

+ The wavelength dispersion curve of the retardation film produced in Comparative Example 7 is shown.

2

The case where the retardation film in Example 12 is inclined in the phase retardation axis direction is shown.

(Triangle | delta) The case where the retardation film in Example 12 is inclined in the phase progress axis direction is shown.

■ The case where the retardation film in Example 13 is inclined in the phase retardation axis direction is shown.

The case where the retardation film in Example 13 is inclined in the phase progress axis direction is shown.

The case where the retardation film in Example 14 is inclined in the phase retardation axis direction is shown.

The case where the retardation film in Example 14 is inclined in the phase progress axis direction is shown.

◆ The case where the retardation film in Example 18 is inclined in the phase retardation axis direction is shown.

-Shows the case where the retardation film in Example 18 is inclined in the phase advancing axis direction.

The cellulose which can be used as a starting material in the present invention is a structure in which the monomer 1 unit represented by formula (3) is linked regardless of the crystal form or degree of polymerization,

식(3)

Formula (3)

That is, D-glucopyranose can be used as long as it is a structure linked by (ß-1,4 bonds.) In the above formula, n represents the number of connections of units, usually 10 or more, preferably 50 or more, more preferably. Is 100 or more, and the upper limit is not particularly limited, but is usually 10000 or less, preferably 5000 or less, and more preferably 2000 or less. Specifically, natural cellulose, powdered cellulose, crystalline cellulose, regenerated cellulose, cellulose hydrate, or rayon may be used. Moreover, when quality uniformity etc. are requested | required, it is preferable to use what adjusted the number of connection (polymerization water) artificially, and in that case, n is about 100-1000, and in some cases, 150-600. It is desirable to have a degree.

The three-dimensional refractive index formed by uniaxial stretching of the film is nx> ny> nz or nz≥ny> nx or ny> nz> nx (the refractive index in the stretching direction is nx, and the refractive index in the direction orthogonal to it is ny and the thickness direction The cellulose derivative used also for producing the retardation film of this invention whose refractive index is zn) is what substituted the hydroxyl group of cellulose with C5-C20 aliphatic acyl group, and can be represented by following formula (4).

식(4)

Formula (4)

N in Formula (4) is as above-mentioned, and R <^1> , R <^2> and R <^3> are hydrogen atoms or a substituent. R ¹ , R ² and R ³ may be the same or different, but not all of R ¹ , R ² and R ³ are hydrogen atoms, at least one of C 5 to C 20, more preferably C 5 to C 16, More preferably, they are C5-C12 linear aliphatic acyl group, and the remaining group may be substituted by other substituent.

In the cellulose derivative substituted with the C5-C20 aliphatic acyl group, the number of substituents (hereinafter referred to as "substitution degree") per one cellulose monomer differs according to the carbon number of the linear acyl group to be used. For example, in the case of cellulose n-pentanate, substitution degree becomes like this. Preferably it is 2.0-3.0, More preferably, it is obtained by uniaxially stretching the film which consists of this cellulose n-pentanate. The retardation film of the present invention is nx> ny> nz (refractive index in the stretching direction is nx, the refractive index in the direction orthogonal to it is ny, the refractive index in the thickness direction is zn), and the wavelength dispersion characteristic is wavelength 550 The so-called achromaticity can be imparted so that the phase difference value on the long wavelength side is larger than the phase difference value at nm, and the phase difference value on the short wavelength side is smaller than the phase difference value at wavelength 550 nm. Moreover, when cellulose n-hexanate is used, substitution degree becomes like this. Preferably it is 2.0-2.9, More preferably, it is 2.0-2.8, More preferably, the film which consists of this cellulose n-hexanate The retardation film of the present invention obtained by uniaxial stretching of nx> ny> nz (refractive index in the stretching direction is nx, the refractive index of the direction orthogonal to it in the plane is ny, the refractive index in the thickness direction is zn), The so-called achromaticity can be imparted so that the wavelength dispersion characteristic is larger in the phase difference value on the long wavelength side than the phase difference value in the wavelength 550 nm, and the phase difference value on the short wavelength side becomes smaller than the phase difference value in the wavelength 550 nm. Similarly, nx> ny> nz, and the wavelength dispersion characteristic is so that the phase difference value on the long wavelength side is larger than the phase difference value on the wavelength 550 nm, and the phase difference value on the short wavelength side is smaller than the phase difference value on the wavelength 550 nm. So-called achromatic properties can be imparted. In the case of cellulose n-heptanate, the degree of substitution is set to 1.5 to 2.3, whereby nx> ny> nz, and the wavelength dispersion characteristic is smaller on the longer wavelength side than the phase difference on the wavelength of 550 nm. The retardation value on the short wavelength side is larger than the retardation value at the wavelength of 550 nm.

Further, if the degree of substitution of cellulose n-heptanate is 2.5 to 3.0, more preferably 2.7 to 3.0, the stretching direction in the film plane (or the direction orthogonal to it in the film plane) is carried out by performing normal uniaxial stretching. ) And biaxiality oriented in two directions in the thickness direction (hereinafter also referred to as biaxiality), and the wavelength dispersion characteristic is longer than 550 nm, and the phase difference value on the longer wavelength side is smaller than the phase difference value at 550 nm. The retardation film of the present invention having a retardation value on the shorter wavelength side than 550 nm can be obtained larger than the retardation value at 550 nm. In the case of the present invention, the biaxiality becomes ny> nz> nx or nz≥ny> nx when the refractive index in the stretching direction is nx, the refractive index in the direction orthogonal to it is ny, and the refractive index in the thickness direction is nz. It is characterized by. In addition, cellulose n-octanate, cellulose n-nononate, cellulose n-decanate, cellulose n-undecate, cellulose n-dodecanate, cellulose n-tridecanate, cellulose n- tetradecanate, cellulose n Substituted by 8 to 20 linear acyl groups such as pentadecanate, cellulose n-hexadecanate, cellulose n-heptadecanate, cellulose n-octadecanate, cellulose n-nanodecanate, cellulose n-icosanate, etc. Cellulose derivatives, more preferably cellulose n-octanate, cellulose n-nonanate, cellulose n-decanate, cellulose n-undecanate, cellulose n-dodecanate, cellulose n-tridecanate, cellulose n- Straight chain of 8 to 16 carbon atoms such as tetradecanate, cellulose n-pentadecanate, cellulose n-hexadecanate In the case of an acyl group-substituted cellulose derivative, biaxiality is expressed when the degree of substitution is for example 1.0 to 3.0, preferably 2.5 to 3.0, more preferably 2.5 to 3.0, and the wavelength dispersion is longer than 550 nm. The phase difference value at the side is smaller than the phase difference value at 550 nm, and the phase difference value at the short wavelength side is larger than the phase difference value at 550 nm than 550 nm.

In the case of the present invention, the biaxiality becomes ny> nz> nx and nz≥ny> nx when the refractive index in the stretching direction is nx, the refractive index in the direction orthogonal to it is ny, and the refractive index in the thickness direction is nz. It is characterized by. When an aliphatic substituent having 5 to 20 carbon atoms and a substituent other than this aliphatic substituent are included, when including another substituent, the sum of the substituents of the aliphatic acyl group having 5 to 20 carbon atoms is 2.0 or more, and the sum with other substituent numbers It is 2.5-3.0 per cellulose 1 monomer unit, More preferably, it is 2.7-3.0.

Preferable substituents other than the C5 to C20 aliphatic acyl group in the formula (4) are acyl groups other than a carbamoyl group or a C5 to C20 aliphatic acyl group. Specifically, the group represented by a Y-CO- group or a Z-NH-CO- group is mentioned. Herein, Y is not particularly limited as long as it is a group other than an unsubstituted C5-C20 aliphatic group, and specifically, substituted or unsubstituted C1-C20 hydrocarbon residues excluding unsubstituted C5-C20 aliphatic groups may be mentioned. There is no restriction | limiting in particular as a substituent in this hydrocarbon residue, A hydroxyl group, a halogen atom, an amino group, a cyano group, a C1-C14 acyloxy group, a (C1-C14) alkyloxy group, a phenyl group, a naphthyl group, etc. are mentioned. When this hydrocarbon residue is an aromatic group, C1-C10 alkyl group is mentioned as a substituent.

Examples of the hydrocarbon residue include vinyl group, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, benzyl group, 1-naphthylmethyl group, trifluoromethyl group and amino Methyl group, 2-amino-ethyl group, 3-amino-n-propyl group, 4-amino-n-butyl group, or a group in which their amino group is also converted to an amide or urethane, a hydroxy substituted (C1-C4) alkyl group, Or a vinyl group in which the hydroxyl group is further substituted with a (C1-C14) acyl group or a (C1-C14) alkyl group, or a (C1-C3) alkyl group, or a vinyl group, cyanobiphenyloxy (C3-C10) Aliphatic groups having 1 to 10 carbon atoms unsaturated bonds, such as alkyl groups, phenylacetylenyl (C1-C20) alkyl groups, acetylene groups and cinnamoyl groups, phenyl groups, naphthyl groups, anthracenyl groups, fluorenyl groups, biphenyl groups, 4- The acyl group which has aromatic groups, such as a trifluorophenyl group, is mentioned. Moreover, C1-C10 aliphatic group which may have a substituent as Z is mentioned, (meth) acryloyloxyethyl group, vinyl group, methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, tert-butyl group, pentyl group, neopentyl group, hexyl group, cyclohexyl group, octyl group, nonyl group, decyl group, benzyl group, 1-naphthylmethyl group, trifluoromethyl group, etc. are mentioned, respectively.

These C5 to C20 aliphatic acyl groups and optionally other substituents are suitably one or more according to the birefringence, wavelength dispersion characteristic, viscosity, ease of orientation, processability, reactivity, etc. of the cellulose derivative of the present invention as desired. A plurality of substituents are selected. Moreover, also about substitution degree of a cellulose hydroxyl group, it selects suitably according to birefringence, wavelength-dispersion characteristic, viscosity, ease of orientation, workability, reactivity, etc. of the cellulose derivative of this invention made into the objective.

By introducing a polymerizable group into the cellulose derivative, a phase difference film having excellent mechanical strength, reliability, and solvent resistance can be obtained by imposing a photopolymerization initiator, and irradiating and polymerizing ultraviolet rays after the alignment treatment, if necessary. have. Examples of the polymerizable group include those in which Y and Z are vinyl groups, that is, acryloyl group and methacryloyl group. As a photoinitiator, the compound used for normal ultraviolet curable resin can be used.

Specific examples of this photoinitiator include 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropane-1, 1-hydroxycyclohexylphenyl ketone, and 4- (2-hydroxy). Methoxy) -phenyl (2-hydroxy-2-propyl) ketone, 1- (4-dodecylphenyl) -2-hydroxy-2-methylpropan-1-one, 1- (4-isopropylphenyl)- Acetophenone-based compounds, such as 2-hydroxy-2-methylpropane-1-one, 2-hydroxy-2-methyl-1-phenyl propane-1-one, and diethoxy acetophenone, benzoin, benzoin methyl ether , Benzoin compounds such as benzoin ethyl ether, benzoin isopropyl ether, benzoin isobutyl ether, 2,2-dimethoxy-2-phenylacetophenone, benzoylbenzoic acid, methyl benzoyl benzoate, 4-phenyl benzophenone, and hydroxy Benzophenone compounds such as oxybenzophenone, 4-benzoyl-4'-methyldiphenylsulfide, 3,3'-dimethyl-4-methoxybenzophenone, thioxanthone, 2-chloro thioxanthone, 2-methyl Thioxanthone, 2,4-dime Thioxanthone type compounds, such as thioxanthone, isopropyl thioxanthone, 2, 4- dichloro thioxanthone, 2, 4- diethyl thioxanthone, and 2, 4- diisopropyl thioxanthone, etc. are mentioned. Can be. One type of these photoinitiators can be mixed and used in arbitrary ratios.

When using a benzophenone type compound or a thioxanthone type compound, in order to accelerate | stimulate a photopolymerization reaction, it is also possible to use an adjuvant together. As such an adjuvant, for example, triethanolamine, methyl diethanolamine, triisopropanolamine, n-butylamine, n-methyl diethanolamine, diethylaminoethyl methacrylate, Michler's ketone, 4,4'- dimethyl Amine compounds such as aminophenone, ethyl 4-dimethylaminobenzoate, 4-dimethylaminobenzoic acid (n-butoxy) ethyl or 4-dimethylaminobenzoic acid isoamyl. The content of the photopolymerization initiator is preferably 0.5 parts by weight or more and 10 parts by weight or less, more preferably 100 parts by weight of the (meth) acrylate compound (which also includes this when the polymer has an acryloyl group). 2 weight part or more and 8 weight part or less are preferable. In addition, the amount of the auxiliary agent may be about 0.5 to 2 times the amount of the photopolymerization initiator.

Moreover, although the irradiation amount of an ultraviolet-ray changes with the kind of this liquid crystalline compound composition, the kind and addition amount of a photoinitiator, and a film thickness, about 100-1000 mJ / cm <2> is good. In addition, although the atmosphere at the time of ultraviolet irradiation may be in air or inert gas, such as nitrogen, when it becomes thin, it will not harden enough by oxygen interference, In such a case, it is preferable to irradiate and harden an ultraviolet-ray in an inert gas.

It is also possible to add the reactive monomer different from a cellulose derivative other than the said photoinitiator to the cellulose derivative for producing the retardation film of this invention. As a reactive monomer, the compound which can superpose | polymerize by heat or light is preferable, and the compound which can superpose | polymerize by light, such as an ultraviolet-ray, is preferable. As such a compound, a (meth) acrylate compound is mentioned, for example.

Examples of the (meth) acrylate compound that can be used include trimethylolpropane tri (meth) acrylate, pentaerythritol tri (meth) acrylate, pentaerythritol tetra (meth) acrylate, and ditrimethylolpropane tetra (meth). ) Acrylic acid, dipentaerythritol pentaacrylate, dipentaerythritol hexaacrylate, pentaerythritol tri (meth) acrylate and a reaction product of 1,6-hexamethylene disocyanate, pentaerythritol tree Reaction product of (meth) acrylate with isohorone disocyanate, tris (acryloxyethyl) isocyanurate, tris (methacrylooxyethyl) isocyanurate, glycerol triglycidyl ether and (meth) acrylic acid Reaction product with, caprolactone modified tris (acryloxyethyl) isocyanurate, trimethylol propane triglycidyl ether Reaction product of and (meth) acrylic acid, triglycerol di (meth) acrylate, reaction product of propylene glycol diglycidyl ether and (meth) acrylic acid, polypropylene glycol di (meth) acrylate, tripropylene glycol di (Meth) acrylate, polyethylene glycol di (meth) acrylate, tetraethylene glycol di (meth) acrylate, triethylene glycol di (meth) acrylate, pentaerythritol di (meth) acrylate, 1,6-hexane Reaction products of diol diglycidyl ether and (meth) acrylic acid, 1,6-hexanediol di (meth) acrylate, glycerol di (meth) acrylate, ethylene glycol diglycidyl ether and (meth) acrylic acid Reaction product of diethylene glycol diglycidyl ether and (meth) acrylic acid, bis (acryloxyethyl) hydroxyethyl isocyanurate, bis (methacrylooxyethyl) Doxyethyl isocyanurate, reaction product of bisphenol A diglycidyl ether and (meth) acrylic acid, tetrahydrofurfuryl (meth) acrylate, caprolactone modified tetrahydrofurfuryl (meth) acrylate, 2- Hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, polypropylene glycol (meth) acrylate, polyethylene glycol (meth) acrylate, phenoxyhydroxypropyl (meth) acrylate, acrylo Succinate, methoxypolyethylene glycol (meth) acrylate, methoxy tetra ethylene glycol (meth) acrylate, methoxytriethylene glycol (meth) acrylate, methoxy ethylene glycol (meth) acrylate, methoxy Ethyl (meth) acrylate, glycidyl (meth) acrylate, glycerol (meth) acrylate, ethyl carbitol (meth) acrylate, 2-ethoxyethyl (meth) arc Elate, N, N-dimethylaminoethyl (meth) acrylate, 2-cyanoethyl (meth) acrylate, reaction product of butylglycidyl ether and (meth) acrylic acid, butoxytriethylene glycol (meth) acrylic acid The rate or butanediol mono (meth) acrylate etc. are mentioned. These compounds may be used alone or in combination of a plurality thereof. By polymerizing on the appropriate conditions using such a reactive compound, a desired orientation state can be fixed.

Moreover, it is also possible to bridge | crosslink the remaining hydroxyl group of the said cellulose derivative with a crosslinking agent. As a crosslinking agent, isocyanate type, such as collonate HL (manufactured by Nippon Polyurethane Co., Ltd.), L-45 (manufactured by Sooken Chemical Co., Ltd.), duranate (manufactured by Asahi Kasei Co., Ltd.), and semizule (manufactured by Juka Bayer Urethane Co., Ltd.), can be suitably used. Moreover, in order to accelerate crosslinking reaction, you may add catalysts, such as dibutyl dilauric acid tin. It is preferable to perform these crosslinking reaction in any one of the processes at the time of film formation, extending | stretching, and extending | stretching at the time of manufacturing the retardation film of this invention. Specifically, in the presence of the crosslinking agent or the catalyst, when the film is formed, it is achieved by heat-treating the obtained retardation film at the time of heating during drying, at the time of stretching during heating, or after stretching. For example, as a method of crosslinking the remaining hydroxyl group of the cellulose derivative of the present invention with a crosslinking agent, when a duranate (manufactured by Asahi Kasei) is used as the crosslinking agent, the amount of the crosslinking agent to be used is 0.1 to the cellulose derivative. Wt% to 50 wt%, preferably 0.5 wt% to 30 wt%, more preferably 1 wt% to 15 wt%. Moreover, the drying temperature at the time of film formation is performed in 20 to 160 degreeC, Especially, the range of 70 to 130 degreeC is preferable.

Next, the three-dimensional refractive index at the measurement wavelength of 590 nm is ny> nx (nx is the refractive index in the stretching direction in the retardation film plane, and ny is the refractive index in the stretching direction and orthogonal direction in the retardation film plane). As for the cellulose derivative used for producing the retardation film of this invention which satisfy | fills and is 110 degreeC or more in heat resistance, each substituent (R1, R2, and R3) in following formula (4) has the following range. . That is, at least one hydroxyl group of a cellulose unit is substituted by C8-C20 aliphatic acyl group.

식(4)

Formula (4)

In Formula (4), n is as above-mentioned, and R <^1> , R <^2> and R <^3> are hydrogen atoms or a substituent. There is no indication that all of R ¹ , R ² and R ³ are hydrogen atoms, and at least one is an aliphatic acyl group of C8 to C20, more preferably C8 to C16, more preferably C8 to C12. In particular, by using C8 to C12 aliphatic acyl groups, the solubility in a solvent is good, the processability is easy, and the obtained retardation film also has an appropriate strength.

In the cellulose derivative substituted with the said C8-C20 aliphatic acyl group, heat resistance can be improved by adjusting a substitution degree. Heat resistance is a temperature at which a film does not melt, and in the retardation film of this invention, heat resistance is 110 degreeC or more, More preferably, it is 120 degreeC or more, More preferably, it is 130 degreeC or more. The number of substituents (hereinafter referred to as "substitution degree") per cellulose monomer unit of the cellulose derivative which can be used for the retardation film of the present invention is not a problem as long as it is 1.0 or more and less than 2.9, and usually 1.5 or more and less than 2.9, more preferably 1.8 It is less than 2.9. By carrying out normal uniaxial stretching using the cellulose derivative of such a degree of substitution, not only the heat resistance is excellent, but also the stretching direction in the film plane (or the direction orthogonal to it in the film plane) and the thickness direction in two directions. It is possible to obtain a retardation film having a biaxially oriented orientation (also referred to as biaxiality after this). This biaxial property is characterized in that when the refractive index in the stretching direction is nx, the refractive index in the direction orthogonal to it is ny, and the refractive index in the thickness direction is nz, ny> nz> nx and nz≥ny> nx. This biaxiality is cellulose n-octanate, cellulose n-nonanate, cellulose n-decanate, cellulose n-undecate, cellulose n-dodecanate, cellulose n-tridecanate, cellulose n-tetradecanate, cellulose substituted with acyl groups having 8 to 20 carbon atoms such as n-pentadecanate, cellulose n-hexadecanate, cellulose n-heptadecanate, cellulose n-octadecanate, cellulose n-nanodecanate or cellulose n-icosanate Expressed when cellulose is used, more preferably cellulose n-octanate, cellulose n-nononate, cellulose n-decanate, cellulose n-undecate, cellulose n-dodecanate, cellulose n -Tridecanate, cellulose n-tetradecanate, cellulose n-pentadecanate or cellulose Cellulose substituted with an acyl group having 8 to 16 carbon atoms such as n-hexadecanate, more preferably cellulose n-octanate, cellulose n-nononate, cellulose n-decanate, cellulose n-undecate or cellulose n -It is preferable to use cellulose substituted with an acyl group having 8 to 12 carbon atoms such as dodecanate. In the case of cellulose substituted with an acyl group having 8 to 12 carbon atoms, the degree of substitution is, for example, 1.0 or more and less than 2.9, more preferably 1.5 or more and less than 2.9, and more preferably 1.9 or more and less than 2.9, thereby heating to 160 ° C. This retardation film is particularly preferable because it does not melt and can provide excellent heat resistance and biaxiality.

Moreover, the degree of biaxiality can be understood by calculating the ratio of the phase difference value in the front direction of a retardation film, and the phase difference value at the time of inclination of fixed angle in a phase retardation axis direction and a phase advancing axis direction. In the case of the retardation film of this invention, when the retardation value at the time of inclining 50 degrees to R (0) and a phase traveling axis direction in the phase direction value of this retardation film in wavelength 590nm is R (50). When the ratio R (50) / R (0) is 0.5 or more and 1.1 or less, more preferably 0.8 or more and 1.1 or less, more preferably 0.95 or more and 1.05 or less, the inclination with the phase difference value in the front direction Since the difference with the phase difference value becomes small, the viewing angle characteristic is improved.

The substituent of these C8-C20 aliphatic acyl groups selects a preferable substituent according to birefringence, viscosity, ease of orientation, processability, reactivity, etc. of the cellulose derivative of this invention made into the objective. Moreover, also about substitution degree of a cellulose hydroxyl group, it selects suitably according to birefringence, viscosity, the ease of orientation, workability, reactivity, etc. of the cellulose derivative of this invention made into the objective.

Moreover, the cellulose ester which can be used for manufacture of the said crosslinked cellulose derivative is substituted by C7-C20 aliphatic acyl group in the cellulose derivative used for the retardation film of the said invention, and it is preferable that substitution degree is 1.0 or more and less than 2.9. Such a cellulose ester has each substituent in following formula (4) of the following ranges.

식(4)

Formula (4)

In formula (4), n is as described above, R ¹ , R ² , and R ³ are hydrogen atoms or substituents, and R ¹ , R ² and R ³ may be the same or different, but R ¹ , R ² and R None of ³ is a hydrogen source, at least one is an aliphatic acyl group of C7 to C20 or C8 to C20, more preferably C8 to C16, more preferably C8 to C12, and the degree of substitution is 1.0 or more and less than 2.9. .

C7-C20 aliphatic acyl group may be represented by X-CO- group, X is n-hexyl, sec-hexyl, cyclohexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n Dodecyl, n-tridecyl, n-tetradecyl, n-pentadecyl, n-hexadecyl, n-heptadecyl, n-octadecyl, n-nonadecyl and the like, and preferably X is n -Hexyl, sec-hexyl, cyclohexyl, n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl and the like. More preferably, in the C8 to C20 aliphatic acyl group, as their preferred ones, X is n-heptyl, n-octyl, n-nonyl, n-decyl, n-undecyl, n-dodecyl and the like. Moreover, a linear C8-C20 aliphatic acyl group is a preferable one. It is usually more preferable to be contained in linear alkyl among the alkyl groups illustrated as said X.

The number of substituents (hereinafter referred to as degree of substitution) per one unit of cellulose of the cellulose ester substituted with the C7 to C20 aliphatic acyl group is not hindered if it is 1.0 or more and less than 2.9, usually 1.5 or more and less than 2.9, more preferably 1.5 or more and 2.8 Is less than.

The crosslinked cellulose derivative has at least one functional group capable of reacting with the cellulose ester and the remaining hydroxyl group of the ester, and also reacts an aliphatic compound (hereinafter referred to as an aliphatic compound for crosslinking) having a crosslinkable functional group, as necessary. It is further obtained by carrying out a polymerization reaction. For example, it can also obtain by crosslinking the said cellulose ester with the aliphatic compound which has 2 or more of functional groups which can react with the remaining hydroxyl group of the said cellulose ester. As said aliphatic compound for crosslinking, for example, an aliphatic compound having functional groups such as formyl group, isocyanate group, thioisocyanate group, carboxyl group, acid anhydride group, sulfonic acid group, epoxy group, vinyl group, halogen atom, allyl group, vinyl ether group Aliphatic compounds having a polymerizable group such as a vinyl group, a (meth) acryloyl group, and an epoxy group are preferable, and more preferably an isocyanate group, a thioisocyanate group, a carboxyl group, an acid anhydride group, a halogenocarbonyl group, a sulfonic acid group, and an allyl It is an aliphatic compound which has group, a vinyl ether group, a vinyl group, a (meth) acryloyl group, and an epoxy group. Preferable carbon number of the aliphatic residue except the said functional group in this aliphatic compound is about 1-20, More preferably, it is 1-15, More preferably, it is about 1-10. In the case where the functional group is two halogenocarbonyl groups, the aliphatic residue preferably has about 5 to 15 carbon atoms. In the aliphatic compound having a polymerizable group (preferably (meth) acryloyl group) and an isocyanate group, there is no problem as long as it is in the above range, but it is preferably about 1 to 10, and more preferably about 1 to 5. As one of these aliphatic compounds, an aliphatic compound having two reactive groups (preferably halogenocarbonyl groups) with a hydroxy group or a reactive group (preferably isocyanate group) with a hydroxy group and a polymerizable group (preferably (meth) And an aliphatic compound containing both of a) acryloyl group). Specific examples of the latter include aliphatic compounds containing an isocyanate group and a (meth) acryloyl group.

One type of these compounds may be used and may be used together two or more types.

As an aliphatic compound which has two halogenocarbonyl groups, the compound represented by Cl (O) C-X1-C (O) Cl is mentioned, for example, X1 is a single bond or a C1-C20 divalent aliphatic residue. Indicates. When X1 is a single bond, this compound is Cl (O) C-C (O) Cl. When X1 is a C1-C20 divalent aliphatic residue, as this aliphatic residue, a linear thing is preferable, More preferably, it is a linear C5-C15 alkyl group.

As an aliphatic compound containing both the reactive group and a polymerizable group with a hydroxyl group, the compound represented by Y1-X2-Y2 is mentioned. X2 represents a C1-C20 divalent aliphatic residue. The aliphatic residue is preferably a linear aliphatic group having 1 to 20 carbon atoms, more preferably a linear alkyl group having 1 to 10 carbon atoms. Y 2 is an isocyanate group —N═C═O or a protected isocyanate group —NC (O) —B. B is a protecting group of isocyanate, but the structure of -ON = C (R1) (R2) is preferable, and R1 and R2 are each hydrogen, methyl group, ethyl group, n-propyl group, n-butyl group, n-pentyl group Which one. Y1 is a polymerizable group, a (meth) acryloyloxy group with an acrylic (CH ₂ = CHC (O) O- or _{CH 2 = C (CH 3)} C (O) O-) are preferred. Specifically, decanediyl di glolide, 2-methacryloyloxyethyl isocyanate, 2-acryloyloxyethyl isocyanate, 1,1- (bisacryloyloxymethyl) ethyl isocyanate, methacrylic acid 2- (0- [1'methylpropylideneamino] carboxy amino) ethyl etc. are mentioned.

Although the addition amount of this aliphatic compound changes with substitution degree of the aliphatic compound, raw material cellulose ester, etc. which are added, about 0.5 parts-20 parts normally with respect to 100 parts (weight) of the said raw material cellulose ester, Preferably it is about 1-15 parts More preferably, it is about 1.5-10 parts, More preferably, it is about 1.5-7 parts.

As one of the methods for forming a crosslinked structure with an aliphatic compound having such a crosslinkable functional group, for example, as described above, an aliphatic compound having at least two functional groups capable of reacting with a hydroxyl group of a cellulose ester, preferably isocyanate When using the compound which has two or more groups, a crosslinked structure can be formed by reacting the raw material cellulose ester which has several residual hydroxyl groups, and a some isocyanate group. Further, for example, a functional group capable of reacting with the hydroxyl group of the cellulose ester (referred to as a reactive functional group), preferably a compound having an isocyanate group and the polymerizable group, preferably a (meth) acryloyl group, is used. For example, after making an isocyanate group and the remaining hydroxyl group of the said cellulose ester react, it is achieved by crosslinking the cellulose ester of this invention by polymerizing the said polymerizable group, for example, a (meth) acryloyl group.

In addition, in order to promote the above-mentioned crosslinking reaction, a heat treatment or a catalyst such as tin dibutyl dilaurate, a condensing agent such as N, N'-dicyclohexylcarbodiimide, or the like can be used as necessary. For example, when making the said isocyanate group and the remaining hydroxyl group of the cellulose ester of this invention react, it is one of the preferable forms to implement in presence of catalysts, such as dibutyl dilauric acid tin. The addition amount of catalysts, such as dibutyl dilauric acid tin, is good in catalytic amount. For example, it is about 0.001 part-about 0.1 part with respect to 100 parts (weight) of raw material cellulose ester.

Moreover, in the cellulose derivative which has photopolymerizable groups, such as the said allyl group, a vinyl ether group, a vinyl group, a (meth) acryloyl group, and an epoxy group, it is also possible to irradiate light and form the crosslinked structure by a polymerization reaction. Light irradiation usually uses ultraviolet irradiation. For example, retardation film excellent in mechanical strength and solvent resistance can be obtained by irradiating and superposing | polymerizing by ultraviolet-ray before an extension or after extending | stretching in presence of a photoinitiator as needed. As a photoinitiator, the compound used for normal ultraviolet curable resin can be used.

Specific examples of the photoinitiator include benzoin compounds such as 2,2-dimethoxy-2-phenylacetophenone, benzophenone compounds such as 4-phenylbenzophenone, and 2,4-diisopropyl thioxanthone. Thioxanthone type compound etc. are mentioned. One type of these photoinitiators can be mixed and used in arbitrary ratios.

Moreover, depending on the kind of photoinitiator, it is also possible to use an adjuvant together in order to accelerate | stimulate a photoinitiation reaction. Examples of such adjuvants include amine compounds such as triethanolamine, methyldiethanolamine, triisopropanolamine, n-butylamine, n-methyldiethanolamine, diethylaminoethyl methacrylate, and the like.

As light irradiation, for example, the irradiation amount of ultraviolet rays varies depending on the kind of the cellulose derivative, the type and content of the photopolymerizable group, and the film thickness, but the first irradiation amount is about 100 to 1000 mJ / cm 2. In addition, although the atmosphere at the time of ultraviolet irradiation may be in air, or inert gas, such as nitrogen, when it becomes thin, it will not harden | cure sufficiently by oxygen interference, In that case, it is preferable to irradiate and harden an ultraviolet-ray in an inert gas.

Usually, since it is difficult to shape | mold on a film after hardening, it is preferable to shape | mold on a film before hardening, and to harden | cure after that.

One preferred method uses a compound having a reactive functional group (preferably an isocyanate group) and the polymerizable group (preferably a (meth) acryloyl group) as an aliphatic compound for crosslinking. It is made to react with the remaining hydroxyl group, it is set as the cellulose ester which has a polymeric group, Next, the solution of this polymeric cellulose ester is apply | coated on a release film, etc., a solvent is removed, and a film is formed. Thereafter, the polymerizable group, for example, a (meth) acryloyl group, may be polymerized to obtain a film made of a crosslinked cellulose derivative.

By carrying out normal uniaxial stretching using a film made of such a cross-linked cellulose derivative, not only the tear strength is excellent, but also the stretching direction (or the direction orthogonal to it in the film plane) without film of coloration. The retardation film which has biaxiality orientated in the two directions of the thickness direction can be obtained (it may also express this biaxiality after this). This biaxial property is characterized in that when the refractive index in the stretching direction is nx, the refractive index in the direction orthogonal to it is ny, and the refractive index in the thickness direction is nz, ny> nz> nx and nz≥ny> nx. This biaxiality is cellulose n-octanate, cellulose n-nonanate, cellulose n-decanate, cellulose n-undecate, cellulose n-dodecanate, cellulose n-tridecanate, cellulose n-tetradecanate, cellulose substituted with 8 to 20 acyl groups such as n-pentadecanate, cellulose n-hexadecanate, cellulose n-heptadecanate, cellulose n-octadecanate, cellulose n-nanodecanate, cellulose n-icosanate, etc. Expressed when cellulose esters are used, more preferably cellulose n-octanate, cellulose n-nononate, cellulose n-decanate, cellulose n-undecate, cellulose n-dodecanate, cellulose n -Tridecanate, cellulose n- tetradecanate, cellulose n-pentadecanate, cellulose cellulose esters substituted with acyl groups having 8 to 16 carbon atoms such as n-hexadecanate, more preferably cellulose n-octanate, cellulose n-nonanate, cellulose n-decanate, cellulose n-undecanate, and cellulose n -It is preferable to use the cellulose ester substituted by the acyl group of 8 to 12 carbon atoms, such as dodecanate. In the case of a cellulose ester substituted with an acyl group having 8 to 12 carbon atoms, the cellulose ester having a substitution degree of, for example, 1.0 or more and less than 2.9, more preferably 1.5 or more and less than 2.9, and more preferably 1.5 or more and less than 2.8 and crosslinked It is particularly preferable to use a cellulose derivative because the tear strength can be improved and biaxiality can be imparted.

Moreover, the degree of biaxiality can be understood by calculating the ratio of the phase difference value in the front direction of a retardation film, and the phase difference value at the time of inclination of fixed angle in a phase retardation axis direction and a phase advancing axis direction. In the case of the retardation film of this invention, when the retardation value at the time of inclining 50 degrees to R (0) and a phase traveling axis direction in the phase direction value of this retardation film in wavelength 590nm is R (50). When the ratio R (50) / R (0) is 0.5 or more and 1.1 or less, more preferably 0.8 or more and 1.1 or less, more preferably 0.95 or more and 1.05 or less, the inclination with the phase difference value in the front direction Since the difference with the phase difference value becomes small, the viewing angle characteristic is improved.

The substituent of these C7-C20 or C8-C20 aliphatic acyl groups selects the preferable substituent according to birefringence, viscosity, ease of orientation, workability, reactivity, etc. of the cellulose derivative of this invention made into the objective. Moreover, also about substitution degree of a cellulose hydroxyl group, it selects suitably according to birefringence, viscosity, the ease of orientation, workability, or reactivity of the cellulose derivative of this invention made into the objective.

The concrete synthesis | combining method of the cellulose derivative used by this invention is shown.

The cellulose derivative of this invention can be obtained by making the cellulose represented by Formula (3) react with the reagent corresponding to a substituent. For example, by dissolving cellulose impregnated with N and N-dimethylacetamide in a mixed solution of lithium chloride and N, N-dimethylacetamide, and then reacting by adding a C5 to C20 aliphatic carboxylic acid halide corresponding to a substituent, The cellulose acrelite in which the hydroxyl group of the cellulose is substituted with the acyl group is obtained. Moreover, as another method of acylation, a cellulose acrilate can be similarly obtained by making cellulose react in the liquid mixture of trifluoroacetic anhydride and C5-C20 aliphatic carboxylic acid corresponding to a substituent. By suitably selecting the reaction conditions of this reaction, the substitution degree of each cellulose derivative can be controlled. For example, in the case of cellulose acrylate, the method of using the carboxylic acid halide is a suitable method when obtaining a cellulose acrylate having a degree of substitution of about 1.0 to 2.8. On the other hand, the method of using trifluoroacetic anhydride and carboxylic acid is the method suitable when obtaining cellulose acrylate with substitution degree 2.5-3.0. In order to more precisely control the substitution degree, it is achieved by appropriately adjusting the amount of each reagent used in the reaction, the reaction temperature, the reaction time and the like. After the reaction, the product is precipitated by adding a reaction solution in water or methanol, washed with water or methanol and purified. The obtained solid content can be dried and the cellulose derivative of this invention can be obtained.

Substitution degree adjustment of the cellulose derivative of this invention is achieved by adjusting the quantity of the reagent for substituent introduction used at the time of this cellulose derivative synthesis | combination. The reagent for introducing substituents may be used in the range of 0.5 to 100 equivalents relative to the amount of hydroxyl groups in the cellulose used in the reaction raw materials, and the more used, the higher the degree of substitution of cellulose derivatives can be obtained. Since the reactivity is different from each other, the amount of the reagent for introducing a substituent required to achieve a certain degree of substitution is different. Moreover, as another method of adjusting substitution degree, the method of hydrolyzing the obtained cellulose acrylate using alkaline aqueous solutions, such as potassium hydroxide and sodium hydroxide aqueous solution, is mentioned. The degree of hydrolysis may be appropriately adjusted according to the concentration, temperature, treatment time and the like of the alkaline aqueous solution to be used.

For example, when obtaining cellulose n-hexanate of substitution degree 2.1, reaction is performed for 4 hours or more using 1.05 equivalent n-hexanoyl chloride with respect to the hydroxyl group of a cellulose. On the other hand, when obtaining the cellulose n-hexanate of substitution degree 2.7, reaction is performed for 4 hours or more using 1.50 equivalent n-hexanoyl chloride with respect to the hydroxyl group of a cellulose.

Moreover, in order to improve tear strength, the obtained cellulose ester and the said aliphatic compound for crosslinking are made to react. This reaction may be carried out during the film formation conduction described later, or may be carried out after stretching. In the case of carrying out before the film formation, for example, the cellulose ester is dissolved in an organic solvent, and then crosslinked. A cellulose ester having a polymerizable group can be obtained by adding a aliphatic compound for the reaction and further reacting with heat treatment or a catalyst or a condensing agent, if necessary. The obtained cellulose ester which has a polymeric group may be crystallized with water etc., and may be used as it is. Usually, the temperature of heat processing consists of 20 degreeC-160 degreeC, and the range of 30 degreeC-110 degreeC is especially suitable.

Preparation of the retardation film of this invention using the said cellulose derivative is performed by film formation (and superposition | polymerization reaction as needed) from an cellulose derivative (including the cellulose ester which has the said polymeric group) solution, and an orientation treatment. As a specific method, this cellulose derivative is first dissolved in a solvent. Examples of solvents that can be used include halogenated hydrocarbon solvents such as methylene chloride and chloroform, acetic acid esters such as ethyl acetate, butyl acetate and methyl acetate, alcohols such as methanol, ethanol, propanol, isopropanol and benzyl alcohol, 2-butanone and acetone And ketones such as cyclopentanone and cyclohexanone, base solvents such as benzylamino, triethylamine and pyridine, and nonpolar solvents such as cyclohexane, benzene, toluene, xylene, anisole, hexane and heptane. The weight concentration of this cellulose derivative is usually 1% to 99%, preferably 2.5% to 80%, more preferably 5% to 50%. One type of these compounds can be mix | blended and multiple components can also be mix | blended. Moreover, each solvent and plasticizer mentioned above can also be added as needed. Examples of plasticizers include dimethyl phthalate, diethyl phthalate, phthalic acid esters such as ethyl phthalyl ethyl glycolate, trimellitic acid esters such as tris (2-ethylhexyl) trimellitate, and aliphatic 2 such as dimethyl adipate or dibutyl adipate. Basic acid esters, phosphate esters such as tributyl phosphate and triphenyl phosphate, sebacic acid esters such as sebacic acid-di-n-butyl, and acetate esters such as glycertriacetate or 2-ethylhexyl acetate. Only one type of these compounds may be blended or a plurality of components may be blended.

Subsequently, the obtained cellulose derivative solution is applied onto a substrate having a flat release property on the surface, and then the solvent is removed by natural drying or heat drying, and peeled off from the substrate to obtain a transparent cellulose derivative film. Or halogenated hydrocarbon solvents such as methylene chloride and chloroform, the ketones such as 2-butanone, acetone, cyclopentanone, and cyclohexanone, and the like, wherein the cellulose ester used as a raw material of the cellulose ester having the polymerizable group is used; After dissolving in a base solvent such as triethylamine and pyridine, acetic acid esters, alcohols, nonpolar solvents, and the like, a crosslinking aliphatic compound and a catalyst, if necessary, are added, and then a film is formed similarly. At this time, crosslinking reaction is performed by heating at the time of solvent removal in drying, heat treatment or ultraviolet irradiation after solvent removal, and the film which consists of crosslinked cellulose derivatives can be obtained. As a crosslinking agent, the compound which has functional groups, such as an isocyanate group, a thioisocyanate group, or a carboxyl group, or polymerizable groups, such as a vinyl group and a methacryloyl group, is mentioned. One type of these crosslinking agents may be mix | blended, and multiple components may be mix | blended.

The retardation film of this invention can be obtained by uniaxially stretching the cellulose derivative film obtained in this way. The extending | stretching process can use general uniaxial stretching, For example, it extends in one direction, fixing and heating both ends of this cellulose derivative film. Or when a film is a roll shape horizontally long, both ends of a film are fixed with a nip roll, for example, and it extends continuously by the difference of the rotation speed of both rolls. When extending | stretching, the suitable extending | stretching temperature differs according to the kind and substitution degree of the substituent of a cellulose derivative.

The drawing temperature for producing the retardation film of this invention obtained by uniaxially stretching the film which consists of a cellulose derivative in which the hydroxyl group of cellulose is substituted by the acyl group of 5-20 carbon atoms is 50 degreeC-200 degreeC, More preferably, 50 to 180 degreeC is good. For example, in the case of the cellulose n-hexanate whose substitution degree of a hexanoyl group is 2.0-3.0, it is 90 degreeC-160 degreeC.

Moreover, the extending | stretching temperature for producing the retardation film of this invention formed by extending | stretching the said heat resistant cellulose derivative is 40 degreeC-160 degreeC, More preferably, it is about 45 degreeC-140 degreeC. For example, in the case of the cellulose n-decanate whose substitution degree of decanoyl group is 2.2 or more and less than 2.9, it is 45 degreeC-140 degreeC.

Moreover, the extending | stretching temperature for producing the retardation film of this invention formed by extending | stretching the said crosslinked cellulose derivative is 40 degreeC-160 degreeC, More preferably, about 45 degreeC-140 degreeC is good.

The stretching ratio depends on the type, thickness, and desired phase difference value of the cellulose derivative, but is preferably 1.05 to 5.0 times, more preferably 1.1 to 4.0 times. For example, when the degree of substitution of the hexanoyl group is cellulose n-hexanate of 2.0 to 3.0, it is about 1.1 to 3.0 times. The drawing speed also differs depending on the kind of cellulose derivative as the drawing temperature, but the drawing speed is usually 5 times drawing / minute or less, preferably 3 times drawing / minute or less, and more preferably 2 times drawing / minute or less.

When uniaxially stretching this cellulose ester containing an aliphatic compound for crosslinking, it is crosslinked by heat treatment or ultraviolet irradiation after uniaxial stretching, and the retardation film of this invention using a crosslinked cellulose derivative can be obtained. Moreover, when uniaxially stretching the cellulose ester which has a polymeric group, the retardation film of this invention can be obtained by superposing | polymerizing by ultraviolet irradiation etc. after uniaxial stretching.

The retardation value in wavelength 550nm of the film front direction of the retardation film of this invention obtained in this way is about 10-600 nm.

Moreover, the thickness of the retardation film obtained by this invention is 10-500 micrometers, Preferably it is 20-300 micrometers, More preferably, it is about 30-150 micrometers.

In the retardation film of this invention which consists of cellulose n-pentanate of substitution degree 2.0-2.8 or cellulose n-hexanate of substitution degree 2.0-2.5, draw ratio is 1.5-2.0 times and thickness is 50-100 micrometers. By the above-described general uniaxial stretching only, when the refractive index in the stretching direction as described above is nx, the refractive index in the direction orthogonal to it is ny, and the refractive index in the thickness direction is nz, nx> ny> nz. It is especially preferable because a retardation film having the same biaxiality and having an achromatic wavelength dispersion characteristic can be obtained.

Further, cellulose n-heptanate having a degree of substitution of 2.5 to 2.99, cellulose n-octanate, cellulose n-nononate, cellulose n-decanate, cellulose n-undecate, and cellulose n- having a degree of substitution of 1.0 to 2.99. Dodecanate, cellulose n-tridecanate, cellulose n-tetradecanate, cellulose n-pentadecanate, cellulose n-hexadecanate, cellulose n-heptadecanate, cellulose n-octadecanate, cellulose n-nano Cellulose derivative substituted by C7-C20 linear acyl groups, such as decanate and cellulose n-icosanate, More preferably, cellulose n-heptanate of 2.7-3.0 substitution degree, Cellulose of 2.0-3.0 substitution degree n-octanate, cellulose n-nonanate, cellulose n-decanate, cellulose n-undecanate, cellulose n-dodecanate, cellulose n- In the case of a cellulose derivative substituted by a C7-C16 straight-chain acyl group, such as a lidideate, a cellulose n- tetradecanate, a cellulose n-pentadecanate, and a cellulose n-hexadecanate, in general uniaxial stretching, Thus, it has the biaxiality of ny> nz> nx or nz≥ny> nx (refractive index of extending | stretching direction is nx, the refractive index of the direction orthogonal to it in this plane is ny, and the refractive index of thickness direction is called nz), Moreover, the retardation film whose wavelength dispersion characteristic is smaller than the retardation value in the long wavelength side rather than 550 nm is smaller than the retardation value in 550 nm, and whose retardation value in the short wavelength side becomes larger than the retardation value in 550 nm than 550 nm can be obtained. have. Therefore, the retardation film which has biaxiality and has said wavelength dispersion characteristic can be manufactured, without employ | adopting cumbersome means, such as adhering a shrinkable film as described in patent document 3, and the like.

As general uniaxial stretching, for example, both ends of the cellulose derivative film are fixed and warmed to 40 ° C. to 200 ° C., more preferably 50 ° C. to 180 ° C., and 1.05 to 5.0 times in one direction, more preferably 1.1 to 4.0. When the film is stretched about twice or the film is in a roll shape that is horizontally long, for example, both ends of the film are fixed with a nip roll, and both sides are heated under a heating atmosphere of 40 ° C. to 200 ° C., more preferably about 50 ° C. to 180 ° C. The method of extending | stretching continuously from 1.05 times to 5.0 times, More preferably, from 1.1 times to 4.0 times by the difference of the rotation speed of a roll, etc. are mentioned.

Moreover, in the retardation film of this invention which consists of cellulose n-decanate of substitution degree 2.2 or more and less than 2.9, it is mentioned above only by said general uniaxial stretching by making draw ratio 1.5-4.0 times and thickness 50-150 micrometers. When the refractive index in the drawing direction is nx, the refractive index in the direction orthogonal to it is ny, and the refractive index in the thickness direction is nz, it has biaxiality such that ny> nz> nx, and almost 1/4 wavelength. Retardation film (the retardation value in wavelength 550nm is 130-140 nm) can be obtained.

In the case of forming a film, in the case of using a cellulose ester having a polymerizable group or in the case of using a cellulose ester containing a crosslinking agent, if the polymerization reaction or the crosslinking reaction is not performed before stretching, after the stretching treatment, The polymerization reaction and the crosslinking reaction can be carried out by ultraviolet irradiation, heat treatment or the like to form a retardation film using the crosslinked cellulose derivative of the present invention.

The tear strength of the retardation film using the crosslinked cellulose derivative of the present invention is preferably 400 kg / cm 2 or more. In addition, tear strength is the tear strength measured by extending | stretching at the speed | rate of 20 mm / min of extending | stretching speed at 25 degreeC using the tension tester.

The retardation film of this invention can provide various functions by using it in combination with another retardation film and a polarizing film. For example, when the maximum refractive index in the film plane is na, the refractive index in the direction orthogonal to that in the film plane is nb, and the refractive index in the thickness direction is nc, na> nb> nc, na> nb = nc, na = nb> Each of the retardation films of the present invention, nc, na = nb <nc, na> nc> nb, and nx> ny> nz or ny> nz> nx or nz> ny> nx of the present invention, respectively. By laminating | stacking so that a phase retardation axis may become a desired angle, the composite retardation film of this invention is obtained. Since this composite retardation film differs in wavelength dispersion and viewing angle characteristics from each retardation film alone, further high functionalization is possible. Specifically, for example, the retardation film of the present invention ny> nz> nx or nz≥ny> nx of the present invention and the retardation film of na> nb> nc or na> nb = nc or na = nb> nc, respectively. The composite retardation film obtained by laminating the phase retardation axes in parallel or perpendicular to each other is improved from the viewing angle dependency each has. Moreover, as a method of laminating, the method of sticking with an acrylic adhesive or an adhesive agent is mentioned, for example. An acrylic adhesive can be used suitably as an adhesive at the time of lamination, and various adhesives, such as a polyvinyl alcohol type, a urethane type, an isocyanate type, an acryl type, or an epoxy type, can be used suitably as an adhesive agent. As another retardation film, the retardation film etc. which are obtained by uniaxially or biaxially stretching a polycarbonate, a polyarylate, a polyether sulfone, a norbornene derivative, a cycloolefin type polymer, or the cellulose derivative of patent document 2, 8 are mentioned. . Specifically, for example, the phase difference is about 1/2 of the wavelength (for example, the phase difference value with respect to light having a wavelength of 550 nm is about 200 nm to 300 nm, more preferably 230 nm to 290 nm). Retardation film, polycarbonate, polyarylate, polyethersulfone, uniaxially stretched with a phase difference of about 1/4 of the wavelength (for example, a phase difference value of about 100 nm to 150 nm for light having a wavelength of 550 nm); Another retardation film of na> nb> nc or na> nb = nc consisting of a cycloolefin polymer or the like, or the retardation value is about 1/2 of the wavelength (for example, the retardation value with respect to light having a wavelength of 550 nm is about 200 nm to -300 nm, more preferably 230 nm to 290 nm), and the phase difference is about 1/4 of the wavelength (for example, the phase difference value for light having a wavelength of 550 nm is about 100 nm to 150 nm) ny Phase retardation film (nx direction, ie extending | stretching) of the retardation film of this invention which is> nz> nx or nz≥ny> nx So that the direction) substantially parallel to the phase proceeding axis (stretching direction) of the other phase difference film are laminated by using a pressure-sensitive adhesive or adhesive, it is possible to obtain a composite retardation film of the present invention. This composite retardation film becomes an achromatic (having almost the same retardation with respect to each wavelength) and a 1/4 wavelength retardation film of a wide viewing angle. At this time, when the phase retardation axis of another retardation film is a long direction, and the phase advancing axis of the retardation film of this invention is a long direction, an adhesive layer is formed in the lamination surface side of another retardation film, and the retardation film of this invention By lamination and roll-to-roll, lamination can be performed, and the cost reduction according to the simplification of the process can be realized.

Next, by laminating the retardation film or the composite retardation film of the present invention and the polarizing film, the circular or elliptical polarizing film or the optical film of the present invention can be obtained. Specifically, for example, the phase difference at 550 nm of the retardation film of the present invention is about 1/4 of the wavelength (for example, the phase difference value with respect to light having a wavelength of 550 nm is about 100 nm to 150 nm, preferably 130-140 nm), and the circular polarizing film of this invention can be obtained by laminating | stacking so that the angle formed by the absorption axis of a polarizing film and the phase retardation axis of this retardation film may be 45 degrees or 135 degrees. Under the present circumstances, if a retardation film is the retardation film which has the achromatic property of this invention, it can improve visibility, color reproduction, and contrast by being used for a reflective or reflective semi-transmissive liquid crystal display device. In addition, when the organic EL display device is used, the reflection in the electrode portion can be suppressed, so that the visibility of the display image can be greatly improved. Moreover, if a retardation film is a retardation film which has a biaxial property of this invention, it can improve the viewing angle characteristic of a liquid crystal display device by using it for a reflective or reflective semi-transmissive liquid crystal display device. When the organic EL display device is used, the reflection angle at the electrode portion can be suppressed even when tilted and observed, so that the viewing angle characteristic can be similarly improved. Moreover, when laminating | stacking with the phase retardation axis of a polarizing film and the retardation film of this invention, and the absorption axis of a polarizing film at an angle other than 45 degrees or 135 degrees, the elliptical polarizing film of this invention can be obtained. By using such an elliptical polarizing film in a STN (Superer Twisted Nematic) type liquid crystal display device, the contrast and viewing angle characteristics of a display image can be improved. In addition, when the contrast is improved, it is necessary to optimize the phase difference value and the lamination angle such as compensating the phase difference value of the STN type liquid crystal cell.

Next, the phase difference at 550 nm of the retardation film of the present invention is about 1/2 of the wavelength (for example, the phase difference value with respect to light having a wavelength of 550 nm is about 200 nm to 300 nm, preferably 250 to 290 nm). ), And the optical film of the present invention can be obtained by laminating such that the angle between the absorption axis of the polarizing film and the phase retardation axis of the retardation film is 45 ° or 135 °. In the case where the used retardation film is the retardation film having the achromatic property of the present invention, the use of the beneficiation film in the liquid crystal projector makes it possible to uniformly change the direction of linearly polarized light in a wide wavelength range, and thus the utilization efficiency of light In this case, the degradation of the polarizing film due to absorption of light can be prevented, or the contrast of the display image can be improved. Moreover, when the used retardation film is a retardation film which has biaxiality of this invention, the fall of the optical activity by the change of the retardation value according to inclination can be prevented.

In addition, the optical film of the present invention can be obtained by laminating the phase retardation axis of the retardation film or the composite optical film of the present invention and the absorption axis of the polarizing film to be parallel or orthogonal, more preferably orthogonal. This optical film can also be set as the wide viewing angle polarizing film which improved the viewing angle dependence of a polarizing film. Usually, when two sheets of polarizing film are laminated so that their respective absorption axes are crossed Nichol, the front direction to the film surface may block light transmission, but in a different direction from the direction of each absorption axis, in particular, There exists a problem that light leaks in the position which inclined from the front direction in the direction which shows 45 degree direction in a film plane from an absorption axis direction. This is noticeable as the inclination angle increases. However, with respect to the viewing angle dependence of such a polarizing film, at least one optical film of the present invention is used, and another polarizing film (this may be a normal polarizing film, the optical film of the present invention) to sandwich the retardation film of the present invention. A wide viewing angle polarizing film, which is one example of the present invention, may be laminated so that each absorption axis is crossed Nichol, and tilted from the front direction in a direction different from each absorption axis, in particular, 45 °. , Can suppress the leakage of light. Specifically, the phase shift axis of the retardation film of the present invention having a biaxial property whose retardation value at a wavelength of 550 nm is 50 to 300 nm, preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm. By laminating such that the absorption axes of the polarizing film are substantially parallel, a wide viewing angle polarizing film, which is another example of the optical film of the present invention, can be obtained. At this time, when the polarizing film is elongated and the absorption axis is in the long direction, and the retardation film of the present invention is elongated and the phase progress axis is in the elongated direction, an adhesive or an adhesive layer is formed on the laminated surface side of one film. In this way, lamination by roll-to-roll becomes possible, and the low cost according to the simplification of a process is realized. In addition, by using the optical film in an IPS (In-Plan Switching) type liquid crystal display device or a VA (vertical alignment: vertical alignment) type liquid crystal display device, the viewing angle dependency of the liquid crystal display device can be improved.

Moreover, the phase difference value in wavelength 550nm is nx> ny> nz of this invention which is 50-300 nm, More preferably, it is 100-300 nm, Furthermore, the phase difference film which has an achromatic property, or ny> nz> nx Or nz≥ny> nx, the wavelength dispersion characteristic is smaller than the phase difference value at the longer wavelength side than 550 nm, and the phase difference value at the shorter wavelength side is smaller than the phase difference value at 550 nm than 550 nm. The phase retardation axis of the retardation film having biaxiality as large and the absorption axis or transmission axis of the polarizing film are parallel or orthogonal, and more preferably, the phase retardation axis of the retardation film and the absorption axis of the polarizing film are orthogonal to each other. Viewing angle characteristic of VA type liquid crystal display device by using the optical film of this invention, and the retardation film whose average refractive index in a film plane is no, the refractive index of thickness direction is ne, and has a relationship of ne-no <0. To improve There. As a film like ne-no <0, the retardation film biaxially stretched in the film surface of Unexamined-Japanese-Patent No. 2004-082714, for example, and the ultraviolet region of Unexamined-Japanese-Patent No. 2003-315556 have a selective reflection area | region. Each of the retarded axes of the film obtained by aligning and fixing the cholesteric liquid crystals, or the film obtained by immobilizing the discotech liquid crystal disclosed in Patent 2866372 almost horizontally with respect to the substrate surface and the fixed film or uniaxially stretched film The film laminated | stacked so that it may cross may be mentioned. Specifically, in order to improve the viewing angle characteristic of the VA type liquid crystal display device, when the thickness of the film such that ne-no <0 is d, Rth calculated as Rth = (no-ne) xd is 100 to About 300 nm is preferable, and in order to set it as such Rth, it is achieved by adjusting ne, no, d suitably. At this time, about 0-50 nm may be sufficient as the phase difference value of the film front direction in 550 nm. Lamination | stacking of the film like this ne-no <0 and the retardation film of this invention (In the film like ne-no <0, when there exists a phase difference in a front direction, the phase retardation axis and pattern of this film Lamination | stacking so that the phase retardation axis direction of the retardation film of this invention may become parallel or orthogonal), and the composite optical film of this invention can be obtained by laminating | stacking a polarizing film on the retardation film side of this invention. Lamination | stacking can be performed using an adhesive of acrylic or silicone type | system | group, and an adhesive agent, but especially, using the retardation film of this invention as a board | substrate, and forming an orientation film further on this retardation film (if necessary, on this retardation film, By forming a discotic liquid crystal layer oriented on an alignment film) or a cholesteric liquid crystal layer having a selective reflection region in the ultraviolet region, a substrate for forming a liquid crystal layer is unnecessary, thereby making it possible to reduce the thickness and simplify the process.

As the polarizing film used in the present invention, one having a supporting film on at least one of the polarizing elements may be used. As a polarizing element, thickness 10 obtained by uniaxially stretching the polyvinyl alcohol film which adsorbed and oriented dichroic dyes, such as iodine (poly iodide ion) and a dichroic dye, and carrying out crosslinking treatment with boric acid as needed, for example 10 The polarizing element of about 40 micrometers, and the polyene type polarizing element of about 10-40 micrometers in thickness obtained by carrying out uniaxial stretching of the uniaxially stretched polyvinyl alcohol film after uniaxial stretching can be used. Since the retardation film of this invention improves heat resistance, it is preferable that also the polarizing film used in combination also is excellent in heat resistance, As a polarizing element, what was produced using a dichroic dye is more preferable. As the supporting film, for example, a triacetyl cellulose film obtained by saponifying a surface layer having a thickness of about 40 to 100 µm, or a film made of cycloolefin polymer such as aton (manufactured by JSR) or Zeonoa (manufactured by Nihon Zeon) can be used. . These support films are adhere | attached with a polarizing element with an adhesive agent. If it is a general polarizing film, it is the structure which adhere | attached both sides of the polarizing element using the adhesive agent as said support film. Here, by manufacturing at least one of the said support film into the retardation film of this invention, the thin circular polarizing film, thin optical film, thin elliptical polarizing film, thin optical film, thin composite optical film of this invention obtained by manufacturing Not only can it also serve as a supporting film for a polarizing element, but also it is particularly preferable because it simplifies the bonding process by an adhesive or the like and can thin the whole thickness.

Adhesion between the retardation film and the polarizing element of the present invention can be achieved by using, for example, an isocyanate-based or acrylic emulsion-based adhesive. However, the retardation film of the present invention is saponified by immersing in an aqueous alkaline solution, and the hydrophilicity is reduced. Has the characteristics to be improved. Therefore, it is also possible to use the retardation film of this invention saponified as a support film, and to directly adhere | attach with the polarizing element which comprises a polarizing film using the polyvinyl alcohol-type water-soluble adhesive. By using this saponified retardation film of this invention as at least one support film, it can adhere | attach with a polarizing element using polyvinyl alcohol-type water-soluble adhesive similarly to a normal support film. The circularly polarizing film, the optical film, the elliptical polarizing film, the optical film, and the composite optical film of the present invention thus obtained are separately viewed as adhesives on ordinary polarizing films because the retardation film of the present invention also functions as a support for the polarizing film. Compared with the case where the retardation film of the invention is bonded, it is possible to reduce the thickness and reduce the cost by simplifying the process. In addition, saponification treatment is achieved by washing | cleaning after immersion in alkaline aqueous solution, such as aqueous solution of sodium hydroxide or potassium hydroxide, for a predetermined time. The concentration of sodium hydroxide or potassium hydroxide aqueous solution is 0.5 to 6N, the temperature is about 10 to 60 ° C, and the immersion time is timely adjusted according to the degree of saponification treatment. The degree of saponification can be known by measuring the contact angle of the water in the processed film surface with a contact angle meter. In the saponification process of the retardation film of the present invention, the contact angle of water on the surface of the retardation film of the present invention after saponification is 5 ° or more and 60 ° or less, preferably 5 ° or more and 50 ° or less, more preferably 5 ° or more and 30 ° or less. It is good to be treated as possible.

By using the circular polarizing film of the present invention which also has the support of the polarizing film thus obtained in an image display device or a liquid crystal display device such as an organic EL display device, the viewing angle characteristic and contrast of the displayed image can be improved. . For example, in the case of an organic EL display device, a circular polarizing film for preventing reflection of a metal electrode on the display surface side, by using an acromatic, wide viewing angle circular polarizing film which is one example of the optical film of the present invention described above Since a high reflection prevention effect can be obtained in each wavelength, the contrast of a display image can be improved. In the case of a liquid crystal display device, a reflective or reflective transflective liquid crystal display device uses acromatic and wide viewing angle circular polarizing films, which are one example of the optical film of the present invention, as a circular polarizing film, thereby increasing the Since the anti-reflective effect is maintained not only in the front direction but also when tilted and observed, the contrast of the display image is improved, and the same image as the front can be seen even when tilted, and the viewing angle characteristic can be improved. In the case of a TN type or an OCB type band liquid crystal display device, compensation of a twisted nematic type liquid crystal cell has a hybrid-oriented discotheque liquid crystal layer as described in Japanese Laid-Open Patent Publication No. 2003-315556. Although it can be achieved using a film, the viewing angle characteristic of the polarizing film directly cannot be improved. The same applies to the OCB type liquid crystal cell. However, by using the wide viewing angle polarizing film which is an example of the optical film of this invention together with a TN type liquid crystal cell compensation film, wide viewing angle becomes possible further. Similarly, in the VA-type liquid crystal display device, the composite film of the present invention in which the above-described film such as ne-no <0 and nx> ny> nz and a phase difference film having an achromatic property and a polarizing film are laminated in this order. After the optical film is used or compensation of the VA type liquid crystal cell itself is achieved using a compensation film as described in Japanese Patent No. 2866372, Japanese Patent Application Laid-Open No. 2002-196137, and Japanese Patent No. 2587398, the optical of the present invention is used. By using the film together with the VA liquid crystal cell compensation film, a wider viewing angle can be achieved. For example, after the liquid crystal cell itself is compensated by a compensation film for compensating each liquid crystal cell such as a TN type, an OCB type, a VA, an IPS (In-Plan Switching) type liquid crystal cell, the ny> nz> nx of the present invention. Or nz≥ny> nx, the wavelength dispersion characteristic is smaller than the phase difference value at the longer wavelength side than 550 nm, and the phase difference value at the shorter wavelength side is smaller than the phase difference value at 550 nm than 550 nm. By using the optical film which consists of a retardation film and a polarizing film which have biaxiality as it becomes large, wide viewing angle becomes possible further. At this time, in place of the wide viewing angle polarizing film, a thin wide viewing angle polarizing film (which saponifies the retardation film of the present invention and adhered to the polarizing element with an adhesive), which is an example of the thin optical film of the present invention, The thickness of the whole liquid crystal display device of this invention can be made thin.

As described above, the image display of the present invention includes a circular polarizing film, a polarized light film, an elliptical polarizing film, an optical film, an organic EL display device having a composite optical film, a liquid crystal projector, a liquid crystal display device, and the like using the retardation film of the present invention. The device can impart superior characteristics, such as improved contrast and viewing angle characteristics, as compared with the conventional image display apparatus.

Example

The present invention will be described in more detail with reference to the following Examples.

In addition, the cellulose used as a raw material in the following Example used the cellulose (Miki Industries Co., Ltd.) whose unit number (polymerization degree) represented by Formula (3) is about 300.

Example 1

Cellulose (manufactured by Miki Industrial Co., Ltd.) was impregnated into dimethylacetamide to obtain dimethylacetamide-impregnated cellulose having a cellulose content of 56.4%. Next, 12.6 g of lithium chloride was added to 150 ml of dimethylacetamide, stirred at 80 ° C. for 30 minutes to completely dissolve, and then 3.0 g of dimethylacetamide-impregnated cellulose was added. It stirred at 50 degreeC for 30 minutes, added 6.5 ml of n-valeroyl chloride, It heated up at 80 degreeC again, and stirred for 2.5 hours. Stirring was stopped and the reaction contents were poured into 2 liters of water and the cellulose n-pentanate was reprecipitated. After filtration, the solid obtained by washing three times with 100 ml of water and twice with 50 ml of methanol was vacuum dried for 6 hours to obtain 3.2 g of a white powder of cellulose n-pentanate.

Next, the obtained cellulose n-pentanate was dissolved in a mixed solvent of acetone / DMSO, and hydrolyzed using a 1N sodium hydroxide aqueous solution. At the same time, a solution in which 1N sodium hydroxide aqueous solution of the same amount was added to a mixed solution of acetone / DMSO as a blank was prepared. It was 2.29 when the degree of substitution (number of substitution by the n-pentanoyl group per 1 cellulose unit of cellulose) was computed by reverse titration of both by 1N sulfuric acid.

Next, this cellulose n-pentanate was dissolved in cyclopentanone to give a 10% by weight solution. This solution was apply | coated on the smooth polyester film using the comma coater (made by Hiranotech seed company), and after removing a solvent by heating, it peeled from a polyester film and obtained the film of cellulose n-pentanate.

Next, this film was cut into rectangles, and both ends were fixed, it extended | stretched until it became the original double length on conditions of 150 degreeC, cooled to room temperature, and retardation film (77 micrometers in thickness, 550 nm in thickness) of this invention. Phase difference value 132 nm). The refractive index of this retardation film was measured using an Abbe refractometer (manufactured by Atago, Abbe Refractometer 1T), and the refractive index nx = 1.4827 in the stretching direction and the refractive index in the direction orthogonal to the stretching direction in the film plane were ny = 1.4810 and the refractive index in the thickness direction. nz = 1.4805. Moreover, the phase difference value in each wavelength is measured using the automatic birefringence meter (KOBRA-21ADH, the Oji measurement company), and the ratio of the phase difference value Re550 to 550 nm and phase difference value Ren at each wavelength ( Phase difference ratio: Ren / Re550) was calculated, and the resulting wavelength dispersion characteristics are shown in FIG. Moreover, the phase retardation axis of this retardation film was parallel direction and the extending direction.

Example 2

A cellulose n-hexanate was obtained by the same operation as in Example 1 except that 3.6 ml of n-hexanoyl chloride was used instead of n-valeroyl chloride. The degree of substitution (substitution number of n-hexanoyl groups per cellulose monomer unit) was calculated in the same manner as in Example 1, and the resulting cellulose n-hexanate was 2.43. Next, the film of cellulose n-hexanate was obtained by operation similar to Example 1 except having dissolved cellulose n-hexanate in cyclopentanone and making it a 20 weight% solution. The film was cut into rectangles, fixed at both ends, stretched until the original 1.8 times the length under 120 ° C, cooled to room temperature, and the retardation film of the present invention (thickness 85 µm, retardation value for 550 nm). Nm) was obtained. When the refractive index of this retardation film was measured similarly to Example 1, the refractive index nx = 1.4821 of the extending | stretching direction, the refractive index ny = 1.4805 of the direction orthogonal to the extending | stretching direction in a film plane, and the refractive index nz = 1.4795 of the thickness direction. Moreover, the wavelength dispersion characteristic measured by operation similar to Example 1 is shown in FIG. In addition, the phase retardation axis of this retardation film was a direction parallel to the extending | stretching direction.

Example 3

48 ml of n-heptanoic acid and 39.6 ml of trifluoroacetic anhydride were heated at 55 degreeC, and it stirred for 20 minutes. Next, 1.55 g of cellulose (Miki Industry Co., Ltd.) was added to this mixed solution maintained at 55 ° C, and stirred for 5 hours. This mixture was then added in 1000 ml of methanol, which precipitated out. This was recovered by suction filtration, and the precipitate on the filtrate was sufficiently washed with ethyl acetate and dried in vacuo at 40 ° C. to obtain 3.86 g of cellulose n-heptanate.

Next, the substitution degree was calculated by the same operation as in Example 1, and it was 2.9.

Next, the obtained cellulose n-heptanate was dissolved in chloroform, the 5 weight% solution was adjusted, and the film of cellulose n-heptanate was obtained by operation similar to Example 1. This film was cut | disconnected in rectangle, the both ends of the short side were fixed, and the fixed end was uniaxially stretched in the longitudinal direction until it became the original 2.0 times length in 80 degreeC atmosphere, and the retardation film of this invention was obtained. The film thickness of this retardation film was about 95 micrometers. Next, it was 266 nm when the phase difference value in 590 nm was measured using the automatic birefringence meter (KOBRA-21ADH, the Oji measurement company). Next, when the wavelength dispersion characteristics were measured in the same manner as in Example 1, the phase difference value at the longer wavelength side was smaller than the phase difference value at 550 nm than 550 nm, and the phase difference value at the shorter wavelength side was 550 nm than 550 nm. It was larger than the phase difference value.

In addition, using an Abbe refractometer (manufactured by Atago Co., Ltd., Abbe Refractometer 1T) and measuring the refractive index of the obtained retardation film of the present invention, the refractive index of the stretching direction nx = 1.4732, the refractive index of the direction orthogonal to the stretching direction in the film plane ny = It was 1.4760 and the refractive index nz = 1.4750 of the thickness direction.

Example 4

Cellulose n-octanate was prepared in the same manner as in Example 3, except that 48 ml of n-octanoic acid, 35.4 ml of trifluoroacetic anhydride, and 1.38 g of cellulose (manufactured by Miki Industries Co., Ltd.) were used instead of n-heptanoic acid. 3.16 g was obtained. Next, the substitution degree was calculated by operation similar to Example 1, and the substitution degree was 2.9. This cellulose n-octanate was produced in the same manner as in Example 3 to form a film of cellulose n-octanate. Next, the retardation film of this invention was obtained by operation similar to Example 3 except extending | stretching extending | stretching temperature uniaxially to 2.0 times the original length at 60 degreeC. The film thickness of this retardation film was about 95 micrometers. When the retardation value of the obtained retardation film was measured like Example 3, the retardation value in 590 nm was 370 nm. In addition, as a result of the measurement in the same manner as in Example 3, the refractive index of the obtained retardation film was nx = 1.4720 in refractive direction in the stretching direction, refractive index ny = 1.4759 in the direction orthogonal to the stretching direction in the film plane, and nz = 1.4730 in the thickness direction. Next, the wavelength dispersion characteristic of this retardation film was measured by operation similar to Example 1. The results are shown in FIG. It was found in FIG. 1 that the retardation value on the longer wavelength side was smaller than the retardation value at 550 nm than the 550 nm, and the retardation value at the shorter wavelength side was larger than the retardation value at 550 nm than 550 nm. Moreover, the phase retardation axis of this retardation film was a direction orthogonal to a extending | stretching direction.

Example 5

3.77 g of cellulose n-decanate in the same manner as in Example 3, except that 49.9 g of n-decanoic acid, 33.8 ml of trifluoroacetic anhydride, and 1.32 g of cellulose (manufactured by Miki Industry Co., Ltd.) were used instead of n-heptanoic acid. Got. Next, the degree of substitution was calculated by the same operation as in Example 1, and the degree of substitution was 2.9. This cellulose n-decanate was produced in the same manner as in Example 3 to prepare an unstretched film of cellulose n-decanate. Next, the retardation film of this invention was obtained by operation similar to Example 3 except extending | stretching extending | stretching temperature uniaxially to 2.0 times the original length at 50 degreeC. The film thickness of this retardation film was about 95 micrometers. The retardation value of the obtained retardation film was measured in the same manner as in Example 3, and the retardation value at 590 nm was 267 nm. The refractive index of the obtained retardation film was measured in the same manner as in Example 3, and the refractive index nx = 1.4712 in the stretching direction, the refractive index ny = 1.4740 in the direction orthogonal to the stretching direction in the film plane, and the refractive index nz = 1.4760 in the thickness direction. Next, the wavelength dispersion characteristic of this retardation film was measured by the same operation as in Example 1.

It was found that the phase difference value on the long wavelength side was smaller than the phase difference value at 550 nm than 550 nm, and the phase difference value on the short wavelength side was larger than the phase difference value at 550 nm than 550 nm. Moreover, the phase retardation axis of this retardation film was a direction orthogonal to a extending | stretching direction.

Example 6

8.96 g of cellulose n-laurate was obtained in the same manner as in Example 3 except that 14.3 g of lauric acid was used instead of n-heptanoic acid. Next, the substitution degree was calculated by operation similar to Example 1, and the substitution degree was 2.9. The unstretched film of cellulose n-laurate was produced by operation similar to Example 3 of this cellulose n-laurate. Next, the retardation film of this invention was obtained by operation similar to Example 3 except extending | stretching extending | stretching temperature uniaxially to 1.5 times the original length at 80 degreeC. The film thickness of this retardation film was 130 micrometers. When the retardation value of the obtained retardation film was measured like Example 3, the retardation value in 590 nm was 250 nm. In addition, the refractive index of the obtained retardation film was measured in the same manner as in Example 3, and the refractive index nx = 1.4790 in the stretching direction and the refractive index ny = 1.4810 in the direction orthogonal to the stretching direction in the film plane were the refractive index nz = 1.4818 in the thickness direction. Next, the wavelength dispersion characteristic of this retardation film was measured by operation similar to Example 1. The results are shown in FIG. It was found in FIG. 1 that the retardation value on the longer wavelength side was smaller than the retardation value at 550 nm than the 550 nm, and the retardation value at the shorter wavelength side was larger than the retardation value at 550 nm than 550 nm. Moreover, the phase delay axis of this retardation film was a direction orthogonal to a extending | stretching direction.

Example 7

5.84 g of white powder of cellulose n-palmitate was obtained in the same manner as in Example 3 except that 50 g of palmitic acid was used instead of n-heptanoic acid. Subsequently, the degree of substitution was calculated by the same operation as in Example 1, and the degree of substitution was 2.9. The unstretched film of cellulose n-laurate was produced by operation similar to Example 3 of this cellulose n-laurate. Next, the retardation film of this invention was obtained by operation similar to Example 3 except extending | stretching extending | stretching temperature uniaxially to 1.5 times the original length at 60 degreeC. The film thickness of this retardation film was about 80 micrometers. When the retardation value of the obtained retardation film was measured like Example 3, the retardation value in 590 nm was 120 nm. Moreover, the refractive index of the obtained retardation film was measured similarly to Example 3, and it was refractive index nx = 1.4900 of the extending | stretching direction, refractive index ny = 1.4915 of the direction orthogonal to the extending | stretching direction in a film plane, and refractive index nz = 1.4925 of the thickness direction. Next, the wavelength dispersion characteristic of this retardation film was measured by operation similar to Example 1. The results are shown in FIG. It was found in FIG. 1 that the retardation value on the longer wavelength side was smaller than the retardation value at 550 nm than the 550 nm, and the retardation value at the shorter wavelength side was larger than the retardation value at 550 nm than 550 nm. Moreover, the phase retardation axis of this retardation film was a direction orthogonal to a extending | stretching direction.

Example 8

Cellulose (manufactured by Miki Industries Co., Ltd.) was impregnated into dimethylacetamide to obtain dimethylacetamide-impregnated cellulose having a cellulose content of 52.8%. Next, 16.6 g of lithium chloride was added to 200 ml of dimethylacetamide, and the mixture was completely dissolved by stirring at 80 ° C., and then 4.0 g of dimethylacetamide-impregnated cellulose was added. It stirred at 50 degreeC, added 12.7 g of n-octanoyl chlorides, it heated up at 80 degreeC again, and stirred for 3.5 hours. Stirring was stopped and the reaction contents were poured into 400 ml of water and the cellulose n-octanate crystallized. After filtration, washing with 400 ml of 50% hydrous methanol. The solid obtained by washing twice with 200 ml of methanol was vacuum dried to obtain 6.3 g of a white powder of cellulose n-octanate. The degree of substitution (substitution number with n-octanate per cellulose monomer unit) was 2.87. The degree of substitution of cellulose n-octanate is determined by the ratio of the peak area of 7 hydrogens in one unit of the cellulose monomer and the peak area of 3 hydrogens in the terminal methyl group of the octyl group, using NMR (manufactured by Valerian, 300 MHz). Calculated.

Example 9

62.5 g of lithium chloride was added to 700 ml of dimethylacetamide, and stirred completely at 80 DEG C to completely dissolve, followed by adding 15.0 g of dimethylacetamide-impregnated cellulose obtained in Example 8. It stirred at 50 degreeC, added 28.0 g of n-decanoyl chloride, It heated up at 80 degreeC again, and stirred for 3.5 hours. Stirring was stopped and the reaction contents were poured into 2000 mL of water to crystallize cellulose n-decanate. After filtration, it was washed with 1000 ml of 50% hydrous methanol. The solid obtained by washing twice with 500 ml of methanol was dried in vacuo to give 23.0 g of a white powder of cellulose n-decanate. The degree of substitution (number of substitution by n-decanate per cellulose monomer unit) was calculated to be 2.48. The degree of substitution of cellulose n-decanate was calculated by measuring the amount of residual carboxylic acid when the reaction was terminated by adding water by gas chromatography (HP-5890, manufactured by Adylene Rodis Co., Ltd.).

Example 10

16.6 g of lithium chloride was added to 200 ml of dimethylacetamide, and stirred at 80 ° C. to completely dissolve, followed by adding 4.0 g of dimethylacetamide-impregnated cellulose obtained in Example 8. It stirred at 50 degreeC, added 9.4 g of n-dodecanoyl chloride, It heated up at 80 degreeC again, and stirred for 3.5 hours. Agitation was stopped and the reaction contents were poured into 500 mL of water to crystallize cellulose n-dodecanate. After filtration, washing with 400 ml of 50% hydrous methanol. After washing with 300 ml of methanol, the solid obtained by washing twice with 300 ml of acetone was vacuum dried to obtain 5.7 g of a white powder of cellulose n-dodecanate. The degree of substitution (substitution number with n-dodecanate per cellulose monomer unit) was 2.16. The degree of substitution of cellulose n-do decanate is a ratio of the peak area of seven hydrogens in one unit of the cellulose monomer and the peak area of three hydrogens of the terminal methyl group of the dodecyl group, using NMR (manufactured by Valerian, 300 MHz). Calculated from

Example 11

16.6 g of lithium chloride was added to 200 ml of dimethylacetamide, and stirred completely at 80 ° C. to completely dissolve. Then, 4.0 g of dimethylacetamide-impregnated cellulose obtained in Example 8 was added. It stirred at 50 degreeC, added 11.7 g of n-octanoyl chloride, heated up at 80 degreeC again, and stirred for 3.5 hours. Stirring was stopped and the reaction contents were poured into 500 mL of water to crystallize cellulose n-octanate. After filtration, washing with 200 ml of 50% hydrous methanol. Furthermore, the solid content obtained by washing twice with 200 ml of methanol was dried in vacuo, and 7.5g of white powders of cellulose n-octanate were obtained. The degree of substitution (substitution number with n-octanate per cellulose monomer unit) was calculated to be 2.86. The degree of substitution of cellulose n-octanate was calculated in the same manner as in Example 8 using NMR (manufactured by Varian, 300 MHz).

Example 12

The cellulose n-octanate synthesized in Example 8 was dissolved in chloroform to prepare a 12 wt% solution. This solution was applied onto a release film (Princetek, PET3801) with a comma coater, dried at 40 ° C. to remove the solvent, and then peeled off from the release film to produce a film. The film was cut into rectangles, fixed at both ends, stretched until the original length was about 4 times the length under 100 ° C conditions, cooled to room temperature, and retardation film of the present invention (thickness 87 µm, 590 nm). 387 nm). The phase retardation axis of this retardation film was orthogonal to the extending direction.

The retardation value change when the retardation film was inclined to 50 ° in the phase retardation axis and the phase advancing axis direction, respectively, that is, the viewing angle characteristic of the retardation film was measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji measurement Co., Ltd.), The ratio Rn / Ro of the phase difference value Rn of the wavelength 590 nm in the inclination angle n degrees with respect to the phase difference value Ro of the wavelength 590 nm of the front direction (0 degree) was computed. The results are shown in FIG. Moreover, when the refractive index of the retardation film of this invention obtained using the Abbe refractometer (the Abbe refractometer 1T) was measured, the refractive index of the stretching direction nx = 1.4736, and the refractive index of the direction orthogonal to the extending direction in the film plane ny = It was 1.4774 and the refractive index nz = 1.4774 of the thickness direction.

Example 13

The film was produced by operation similar to Example 12 except having dissolved the cellulose n-decanate synthesize | combined in Example 9 in chloroform and setting it as the 15 weight% solution. The film was cut into rectangles, fixed at both ends, stretched until the original length was about twice the length under 75 ° C conditions, cooled to room temperature, and retardation film of the present invention (thickness of 100 µm, 590 nm). 108 nm). The phase retardation axis of this retardation film was orthogonal to the extending direction. The retardation value change when the retardation film was inclined to 50 ° in the phase retardation axis and the phase advancing axis direction, respectively, that is, the viewing angle characteristic of the retardation film was measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji measurement Co., Ltd.), Ratio Rn / Ro of phase difference value Rn of wavelength 590nm in inclination angle n degrees with respect to phase difference value Ro of wavelength 590nm of front direction (0 degree) was computed. The results are shown in FIG. Moreover, when the refractive index of the retardation film of this invention obtained using the Abbe refractometer (the Abbe refractometer 1T) was measured, the refractive index nx = 1.4757 of the extending | stretching direction, and the refractive index of the direction orthogonal to the extending | stretching direction in a film plane ny = It was 1.4770 and the refractive index nz = 1.4762 of the thickness direction.

Example 14

A film was produced by the same operation as in Example 12, except that the cellulose n-dodecanate synthesized in Example 10 was dissolved in chloroform and a 10% by weight solution was used. The film was cut into rectangles, fixed at both ends, stretched until the original length was about twice as large as the conditions at 57 ° C, cooled to room temperature, and retardation film of the present invention (thickness 125 µm, 590 nm). 192 nm). The phase retardation axis of this retardation film was orthogonal to the extending direction. The retardation value change when the retardation film was inclined to 50 ° in the phase retardation axis and the phase advancing axis direction, respectively, that is, the viewing angle characteristic of the retardation film was measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji measurement Co., Ltd.), Ratio Rn / Ro of phase difference value Rn of wavelength 590nm in inclination angle n degrees with respect to phase difference value Ro of wavelength 590nm of front direction (0 degree) was computed. The results are shown in FIG.

Example 15

The film was produced by operation similar to Example 12 except having melt | dissolved the cellulose n-octaneate synthesize | combined in Example 8 in chloroform and making it the 20 weight% solution of a polymer. The film was cut into rectangles to fix both ends, and the film was stretched until the original length was about 4 times the length under 95 ° C, and the retardation film of the present invention (thickness 58 µm, retardation value of 590 nm for 28 nm) was obtained. Got it. The phase retardation axis of this retardation film was orthogonal to the extending direction.

Example 16

Cellulose (manufactured by Miki Industrial Co., Ltd.) was impregnated into dimethylacetamide to obtain dimethylacetamide-impregnated cellulose having a cellulose content of 53.0%. Next, 41.5 g of lithium chloride was added to 500 ml of dimethylacetamide, and the mixture was completely dissolved by stirring at 80 ° C, and then 10 g of dimethylacetamide-impregnated cellulose was added. It stirred at 50 degreeC, added 19.2 g of n-octanoyl chlorides, it heated up at 80 degreeC again, and stirred for 3.5 hours. Stirring was stopped and the reaction contents were poured into 1000 mL of water to crystallize cellulose n-octanate. After filtration, it was washed with 1000 ml of 50% hydrous methanol. The solid obtained by washing twice with 300 ml of methanol was dried in vacuo to give 15.4 g of a white powder of cellulose n-octanate. The degree of substitution (number of substitutions with n-octanate per cellulose monomer unit) was calculated to be 2.5. The degree of substitution of cellulose n-octanate was calculated from the ratio of the peak area of 7 hydrogens in the cellulose monomer 1 unit and the peak area of 3 hydrogens in the terminal methyl group of the octanoyl group using NMR (Valian Corporation, 300 MHz). .

Example 17

3 g of cellulose n-octanate synthesized in Experimental Example 16 was added to 27 g of cyclopentanone, and it was dissolved by heating at 6 ° C to obtain a 10% by weight solution. After cooling this solution to room temperature, 0.08g of 1 weight% dibutyl dilauric-acid-cyclopentanone solution and 0.19 of 2-methacryloyloxyethyl isocyanate were added, and it stirred at 25 degreeC for 1 hour, Furthermore, it stirred at 60 degreeC for 1 hour. Stirring was stopped and the reaction contents were poured into 400 ml of water to crystallize the cellulose ester having a polymerizable group. After filtration, the solid obtained by washing with 200 ml of methanol was dried at 30 ° C. under atmospheric pressure to obtain 4.6 g of a white powder of cellulose ester having a polymerizable group. If the compound is made into cyclopentanone at a concentration of 10%, the compound does not turn into a solution, but gelates and is dissolved in about 5.7% to obtain a cyclopentanone solution. In this example, instead of cellulose n-octanate, the cellulose n-decanate obtained in Example 9 (degree of substitution 2.48) or the cellulose n-dodecanate obtained in Example 10 (degree of substitution 2.16) was used. By carrying out the process similarly, the cellulose ester which has a polymeric group corresponding to each cellulose ester can be obtained similarly.

Example 18

The cellulose ester (cellulose n-octane having a polymerizable group) having a polymerizable group synthesized in Example 17 was dissolved in chloroform to obtain a 12% by weight solution. This solution was applied onto a release film (Princetek, PET3801) with a comma coater, dried at 40 ° C. to remove the solvent, and then peeled off from the release film to produce a cellulose derivative film. This film was subjected to light irradiation treatment. One light irradiation was carried out four times under the condition that the total light irradiation amount on the surface of the film was 379 mJ / cm 2 using a 4 kW halogen lamp. This film was cut | disconnected in rectangle, and both ends were fixed, it extended | stretched until it became original about 2 times the length on 95 degreeC conditions, cooled to room temperature, and obtained the transparent retardation film of this invention. The retardation value change when the retardation film was inclined to 50 ° in the phase retardation axis and the phase advancing axis direction respectively, that is, the viewing angle characteristic of the retardation film, was measured using an automatic birefringence meter (KOBRA-21ADH, manufactured by Oji measurement Co., Ltd.), Ratio Rn / Ro of phase difference value Rn of wavelength 590nm in inclination angle n degrees with respect to phase difference value Ro of wavelength 590nm of front direction (0 degree) was computed. The results are shown in FIG. Moreover, the phase retardation axis of this retardation film was orthogonal to the extending | stretching direction.

Example 19

When the retardation film of this invention produced in Example 12 was heated to 200 degreeC on the hot stage (made by the Metra Tread Co., Ltd.), the film did not melt even at 160 degreeC. It was visually confirmed that the film did not melt completely. Moreover, although it heated up from 40 degreeC to 200 degreeC by aluminum sealing type using the differential scanning calorimeter (made by Seiko Instle Co., Ltd.), the big endothermic peak seen at the time of melting was not seen.

Example 20

When the retardation film of this invention produced in Example 13 was tested by the same operation as Example 19, the film did not melt even at 160 degreeC. Moreover, although the test of the same method as Example 19 was performed using the differential scanning calorimeter (made by Seiko Instler), the big endothermic peak which can be seen at the time of melting was not seen.

Example 21

When the retardation film of this invention produced in Example 14 was tested by the same operation as Example 19, the film did not melt even at 160 degreeC.

Example 22

The retardation film of the present invention produced in Example 18 was cut into a size of 10 mm x 50 mm and stretched 20 mm / min in a 25 ° C environment using Tenshirron (manufactured by Baldwin, UTM-I-2500). The tear strength at the time of stretching was 424 kg / cm 2.

Example 23

The phase retardation axis of the retardation film of the present invention produced in Example 1 and the absorption axis of the polarizing film (SKN18243T, manufactured by Polar Techno Co., Ltd.) having a thickness of 180 μm are set at an angle of 45 degrees, and laminated using an acryl-based adhesive. The circular polarizing film of was produced. This circular polarizing film had a thickness of 277 μm. Next, the circularly polarizing film was placed on a mirror and the mirror antireflection effect was observed. As a result, the circular polarizing film of the present invention became deep black and had a good antireflection effect.

Example 24

The retardation film of this invention produced in Example 2 was immersed in 60 degreeC and 6N potassium hydroxide aqueous solution for 15 minutes, and it fully wash | cleaned with water. Subsequently, it dried for 30 minutes at 30 degreeC, and obtained the retardation film of this invention in which the surface layer saponified. The contact angle of water on this film surface was 15 degrees. Next, saponification treatment is performed using a polyvinyl alcohol-based adhesive (Nimix Chemical Co., Ltd., NH26) on the polarizing element surface side of a 100 µm thick polarizing film (UDN10243T, manufactured by Polar Techno Co., Ltd.) having a supporting film only on one side of the polarizing element. The retardation film of this invention was adhere | attached by the arrangement which the absorption axis of a polarizing film and the phase retardation axis of this retardation film become 45 degrees, and the circular polarizing film of this invention was obtained. The thickness of the obtained circular polarizing film was 185 micrometers. When the film was evaluated in the same manner as in Example 23, the circular polarizing film of the present invention had a deep black color and had a good antireflection effect.

Example 25

Using the cellulose n-decanate described in Example 9, the retardation film of the present invention was produced in the same manner as in Example 13 except that the stretching temperature was 70 ° C. The thickness of 102 micrometers and the phase difference of the wavelength of 550 nm were 135 nm. This film was immersed in 60N and 6N potassium hydroxide aqueous solution for 10 minutes, and it fully wash | cleaned with water. Subsequently, it dried for 30 minutes at 30 degreeC, and obtained the retardation film of this invention in which the surface saponified. The contact angle of water on the surface of this film was 50 degrees. Next, saponification treatment was carried out using a polyvinyl alcohol-based adhesive (manufactured by Nippon Synthetic Chemical Industry, NH26) on the polarizing element surface side of a 100 µm thick polarizing film (UDN10143P, manufactured by Polar Techno Co., Ltd.) having a supporting film only on one side of the polarizing element. By adhering the retardation film of the present invention, the absorption axis of the polarizing film (stretching direction of the polarizing element) is heated at 70 ° C. for 10 minutes so that the phase propagation axis of the retardation film (the stretching direction of this film) is 45 °. And the thin wide viewing angle circular polarizing film which is one example of the circularly polarizing film of this invention was obtained. The thickness of the whole film was 202 micrometers, and each film was fully bonded. Next, when the circularly polarizing film was placed on a mirror and the mirror antireflection effect was observed, the circularly polarizing film of the present invention exhibited almost the same antireflection effect as in the front direction when viewed from any direction, and was excellent in viewing angle characteristics. Could know.

Example 26

The retardation film of this invention was produced by the method similar to Example 18 using the cellulose ester which has a polymeric group as described in Example 17. The thickness of 127 micrometers and the phase difference of the wavelength of 550 nm were 279 nm. Next, using an acrylic pressure sensitive adhesive in an arrangement in which the absorption axis (stretching direction of the polarizing element) of the polarizing film (SKN18242P manufactured by Polar Techno Co., Ltd.) and the phase traveling axis (stretching direction of this film) of the retardation film of the present invention are parallel to each other. It laminated and obtained the wide viewing angle polarizing film which is an example of the optical film of this invention.

Example 27

The retardation film of this invention was produced by the method similar to Example 15 using the cellulose n-octanate described in Example 11. The thickness was 55 µm and the phase difference between the wavelengths of 550 nm was 271 nm. The retardation film of this invention in which the surface layer saponified was obtained by operation similar to Example 25 of this film. Next, saponification is carried out using a polyvinyl alcohol-based adhesive (manufactured by Nimix Chemical Co., Ltd., NH26) on the polarizing element surface side of a 100 µm thick polarizing film (UDN10143P, manufactured by Polar Techno Co., Ltd.) having a supporting film only on one side of the polarizing element. After the treated retardation film of the present invention is bonded in an arrangement in which the absorption axis (stretching direction of the polarizing element) of the polarizing film is arranged so that the phase progression axis (stretching direction of this film) of the retardation film is parallel, 10 minutes at 70 ° C. By heating, the thin wide viewing angle polarizing film which is one example of the optical film of this invention was obtained. The thickness of the whole film obtained was 155 micrometers, and each film was fully adhere | attaching.

Next, the phase difference of the present invention is such that the absorption axis of one thin optical viewing angle polarizing film, which is one example of the optical film of the present invention, and the absorption axis of another polarizing film (SKN18242P, manufactured by Polar Techno Co., Ltd.) are crossed. The film was laminated so as to be disposed between each polarizing film. Next, it was arrange | positioned on the surface light source in this state, and the state of the light leakage was evaluated in the position which inclined about 50 degrees from the front direction in the direction of 45 degrees from each absorption axis. As a result, in the case of using the wide viewing angle polarizing film which is one example of the optical film of the present invention, it was found that light leakage was hardly observed and light was blocked at a wide viewing angle.

Example 28

Lamination | stacking using an adhesive so that the phase progress axis (stretching direction) of the retardation film of this invention produced in Example 24, and the phase retardation value (stretching direction) of a 120-axis uniaxial stretched polycarbonate film become parallel. By doing this, the composite retardation film of the present invention was obtained. Acryl-based so that the absorption axis of the polarizing film (SKN18243T, manufactured by Polar Techno Co., Ltd.) sandwiching both sides of the retardation film direction of this retardation film and the polarizing element which consists of polyvinyl alcohol which adsorbed and oriented iodine by the triacetyl cellulose film becomes 45 degrees. It laminated | stacked using the adhesive and obtained the circularly polarizing film of this invention. As a result of evaluating this film similarly to Example 23, it was confirmed that the reflection in the front direction was deep black and a good antireflection effect was obtained. Similarly, when the reflection state was evaluated at a position inclined at about 50 ° from the front, left and right, respectively, the reflection remained deep black, and it was found that the achromatic effect was obtained, and the antireflection effect was obtained at a wide viewing angle.

Example 29

Using the cellulose n-decanate described in Example 9, the retardation film of the present invention was produced in the same manner as in Example 13 except that the stretching temperature was 70 ° C. The thickness was 105 µm and the phase difference between the wavelengths of 550 nm was 139 nm. Next, the retardation film of this invention by which surface layer was saponified by this operation similar to Example 25 was obtained. Next, the retardation film in which the retardation value in the film front direction in 550 nm is almost 0 nm, thickness 50 micrometers, and Rth (the difference between the in-plane average refractive index and the refractive index of the thickness direction, and thickness) is nearly 120 nm. (Esshina, Sekisui Chemical Co., Ltd.) was bonded using an acrylic pressure sensitive adhesive to obtain a composite retardation film of the present invention.

Example 30

The retardation film of this invention was produced by the method similar to Example 18 using the cellulose ester which has a polymeric group as described in Example 17. The thickness of 120 micrometers and the phase difference of 550 nm wavelength were 264 nm. Next, an acryl-type adhesive agent so that each phase retardation film may cross | intersect this retardation film of this invention and the retardation film of uniaxially-stretched polycarbonate (65-micrometer-thick, phase difference of wavelength of 550nm is 135 nm) at 60 degrees. It laminated | stacked using and obtained the composite retardation film of this invention. Next, the composite retardation film of the present invention is used so that the absorption axis of the polarizing film (SKN18242P, manufactured by Polar Techno Co., Ltd.) is 75 ° with the phase retardation axis of the retardation film of the present invention whose retardation value is about 1/2 of the wavelength. By laminating | stacking using acrylic adhesive, the achromatic circularly-polarizing film which is one example of the optical film of this invention was obtained. It was arrange | positioned on the mirror in this state, and the leaked state of the reflected light was evaluated in the position which inclined about 50 degrees from the front direction in the direction of 45 degrees from the absorption axis of a polarizing film. As a result, in the case of using the wide viewing angle polarizing film which is one example of the optical film of the present invention, it was found that light leakage was hardly observed and the light was blocked at a wide viewing angle.

Example 31

Phase retardation axis of the retardation film of the saponified present invention used in Example 29 on the polarizing element surface side of a polarizing film (UDN10143P, manufactured by Polar Techno Co., Ltd.) having a thickness of 100 μm having a supporting film on only one side of the polarizing element. (The stretching direction of this film) and the absorption axis (stretching direction of a polarizing element) of this polarizing element are made to adhere using polyvinyl alcohol-type adhesive agent (NH26) from 70 degreeC, and it adhere | attaches, It heated for minutes, and obtained the optical film of this invention. At this time, the polarizing element and the retardation film of this invention were fully adhere | attached. Next, an acrylic pressure-sensitive adhesive on the retardation film side to which the retardation film (Eshina made by Sekisui Chemical Co., Ltd.) whose retardation value in the film front direction at 550 nm is almost 0 nm, thickness 50 µm, and Rth is nearly 120 nm. And the composite optical film of the present invention were obtained. The thickness of this whole film was 280 micrometers.

Example 32

The same operation as in Example 25 was carried out except that the saponified retardation film of the present invention obtained in Example 25 was bonded in such a manner that the absorption axis of the polarizing film and the phase retardation axis of the retardation film were orthogonal to each other. An optical film of was obtained. To the retardation film side of this optical film, the retardation film of the film front direction in 550 nm is substantially 0 nm, thickness 50 micrometers, no-ne = 0.0024, Rth = about 120 nm, using an acrylic adhesive, , The composite optical film of the present invention was obtained.

Example 33

The composite optical film produced in Example 32 was peeled off the commercially available VA type liquid crystal display device, and the polarizing film (SKN18243T, manufactured by Polar Techno Co., Ltd.), which sandwiched both sides of the polarizing element with a triacetyl cellulose film on the backlight side, was observed in Example 32. The film was adhere | attached on the liquid crystal cell using the acrylic adhesive so that the absorption axis of each polarizing film might be orthogonal, and the liquid crystal display device of this invention was obtained. When the backlight of this liquid crystal display device was turned on and the image of a black display state was observed inclined at 45 degrees from the front direction of a display screen in the direction of the absorption axis of a polarizing film, the black state was maintained even if it inclined at 85 degrees. The viewing angle was expanding.

Example 34

The retardation film of this invention produced in Example 5 was saponified by the same operation as Example 24, and the retardation film of this invention in which the surface layer whose water contact angle of the water on a film surface is 50 degrees was saponified. Next, the retardation film of the present invention saponified using a polyvinyl alcohol-based adhesive on the polarizing element surface side of a 100 µm thick polarizing film (UDN10243T, manufactured by Polar Techno Co., Ltd.) having a supporting film only on one side of the polarizing element was used as a polarizing film. The absorption film (direction parallel to the stretching direction) and the phase retardation axis (direction perpendicular to the stretching direction) of the retardation film were laminated so as to be orthogonal to obtain the optical film of the present invention. The total thickness of this optical film was 195 micrometers. Next, the absorption axis of the polarizing film (SKN18243T, manufactured by Polar Techno Co., Ltd.) sandwiching both sides of the other polarizing element of the polarizing film constituting the optical film with a triacetyl cellulose film is crossed Nichol, In addition, the retardation film of the present invention constituting the optical film was laminated so as to be disposed between each polarizing film. Next, it was arrange | positioned on the surface light source in this state, and the light leakage state was evaluated in the position which inclined about 50 degrees from the front direction in the direction of 45 degrees orientation from each absorption axis. As a result, it was found that when the wide viewing angle polarizing film of the present invention was used, light leakage was hardly observed and light was blocked at a wide viewing angle.

Example 35

The polarizing film of commercially available VA type liquid crystal display device was peeled off, and the polarizing film (SKN18242P made from Polar Techno Co., Ltd.) which pinched the polarizing element with two triacetyl cellulose films on the backlight side was produced in Example 31 on the observation surface side. The optical film of the invention is bonded to the liquid crystal cell using an acrylic pressure-sensitive adhesive so that the absorption axis of each polarizing film is perpendicular to each other, and the retardation film side of the optical film of the invention on the observation surface side is the liquid crystal cell plane side. A liquid crystal display device was obtained. When the backlight of this liquid crystal display device was turned on and the image of a black display state was observed inclined in the direction of 45 degrees from the absorption axis direction of a polarizing film from the front direction of a display screen, the black state was maintained even if it was inclined at 85 degrees. The viewing angle was expanding.

Example 36

Wide viewing angle polarization which is an example of the optical film of the present invention produced in Example 26 by peeling off the polarizing film of a commercially available VA type liquid crystal display device, and polarizing film (SKN18242P manufactured by Polar Techno Co., Ltd.) on the back side. An acrylic pressure-sensitive adhesive was placed on the retardation film side in which a retardation film (Eshina, manufactured by Sekisui Chemical Co., Ltd.) having a phase difference value of about 0 nm, a thickness of 50 μm, and Rth of about 550 nm was approximately 120 nm. It bonded together and obtained the optical film of this invention. The liquid crystal display device of the present invention was obtained by adhering the liquid crystal cell using an acrylic pressure-sensitive adhesive so that the absorption axes of the respective polarizing films were perpendicular to each other, and the phase difference film side of the optical film of the present invention on the observation surface side was the liquid crystal cell plane side. . The leak state of light is evaluated at a position where the pack light of the liquid crystal display device is turned on and the image in the black display state is inclined at about 50 ° from the front direction in the direction of 45 ° from the front of the display screen in the direction of the absorption axis of the polarizing film. As a result, the 85 ° inclined black state was maintained, and the viewing angle was enlarged.

Example 37

A mixture of 42.7 g of octanoic acid and 51.9 g of trifluoroacetic anhydride was heated to 50 ° C. and stirred. Next, 2.0 g of cellulose (Miki Industries Co., Ltd.) was added to this liquid mixture maintained at 50 degreeC, and it stirred for 6.5 hours. This mixture was then added in 200 ml of methanol to precipitate a precipitate. The resultant was filtered by suction, washed twice with 200 ml of methanol, and then dried under vacuum at 60 캜 to obtain 5.4 g of a white powder of cellulose n-octanate. The degree of substitution (substitution number with n-octanate per cellulose monomer unit) was 2.94. The degree of substitution of cellulose n-octanate was calculated in the same manner as in Example 8 using NMR (manufactured by Varian, 300 MHz).

Example 38

The film was produced by operation similar to Example 12 except having melt | dissolved the cellulose n-octanate synthesize | combined in the comparative example 1 and made it into the 15 weight% solution. This film was cut | disconnected in rectangle, and the both ends of the short side were fixed, and the fixed end was uniaxially stretched in the longitudinal direction until it became 4 times of the original length at 55 degreeC, and the retardation film was obtained. The thickness of this retardation film was about 77 micrometers. Next, when the phase difference value in 590 nm was measured using the automatic birefringence meter (KOBRA-21ADH, the Oji measurement company make), the phase difference value in 590 nm was 452 nm.

Example 39

When the retardation film produced in Comparative Example 2 was tested in the same manner as in Example 19, when it was heated on a hot stage (manufactured by Metra Tread Co., Ltd.), it began to melt at 94 deg. C and the film was completely formed at about 97 deg. It was visually confirmed to melt. In addition, the same test as in Example 19 was carried out using a differential scanning calorimeter (manufactured by Seiko Instle Co., Ltd.). As a result of heating from 40 ° C to 200 ° C in an aluminum hermetic seal, a large endothermic peak at the time of melting at 81.5 ° C was observed. Confirmed.

Example 40

The cellulose n-octanate synthesized in Example 16 was dissolved in chloroform to make a 15% by weight solution, and this solution was applied on a release film (described by Lintec, PET3801 product name) with a comma coater, and dried at 40 ° C. After removing the solvent, the film was peeled off from the release film to prepare a film. This film was cut | disconnected in rectangle and the both ends of the short side were fixed, it extended | stretched until it became original about 2 times length on 95 degreeC conditions, it cooled to room temperature, and obtained the retardation film of this invention. Moreover, when this retardation film was measured using the automatic birefringence meter (KOBRA-21ADH, the Oji measurement company), the phase retardation axis of this retardation film was orthogonal to the extending | stretching direction.

Example 41

When the retardation film of this invention produced in Example 40 was extended | stretched by the same operation as Example 22, tear strength was 327 kg / cm <2>.

Comparative Example 1

2.5 g of cellulose n-octanate synthesized in Experimental Example 16 was added to 25 g of cyclopentanone and dissolved by heating at 60 ° C. After cooling this solution to room temperature, 0.8 weight of 1 weight% dibutyl dilauric-acid-cyclopentanone solutions, and 0.1 g of 2 and 4-tolylene disocyanate were added, and after stirring at 25 degreeC for 1 hour, Furthermore, it stirred at 60 degreeC for 1 hour. Stirring was stopped and the reaction contents were poured into 300 ml of water and the cellulose derivative was crystallized. After filtration, the solid obtained by washing with 200 ml of methanol was dried at 30C under atmospheric pressure to obtain a cellulose derivative. This cellulose derivative was colored pale yellow.

Comparative Example 2

After dissolving the cellulose derivative synthesized in Comparative Example 1 in toluene to make a 10% by weight solution, this solution was applied on a release film (PET3801, manufactured by Lintec) with a comma coater, dried at 70 ℃ to remove the solvent It peeled from the release film and produced the film. The retardation film obtained by cutting this film into rectangles, fixing both ends of the short side, and extending | stretching until it became about twice the length of the original under 95 degreeC conditions was colored pale yellow.

Comparative Example 3

A circular polarizing film was produced in the same manner as in Example 23, except that the polycarbonate quarter-wave retardation film (the retardation value of the wavelength of 550 nm was 141 nm.) Was observed and the antireflection effect was observed. It was dark purple and did not have sufficient antireflection effect.

Comparative Example 4

Instead of the retardation film of this invention of Example 25, the polarization which carried out the retardation of the wavelength of 550 nm of 65 micrometers which uniaxially stretched polycarbonate, the retardation film of 135 nm, and the polarizing element was sandwiched with two triacetyl cellulose films. The film (SKN18242P by Polar Techno Co., Ltd.) was laminated | stacked using the acrylic adhesive so that the phase retardation axis of retardation film and the absorption axis of polarizing film might be 45 degrees, and the circular polarizing film was produced. The whole polarizing film had a thickness of 270 µm. Next, when evaluating this circularly polarizing film similarly to Example 25, when it inclined from the front direction and the front direction, the antireflection effect fell in the case of inclination, and the viewing angle characteristic was inferior.

Comparative Example 5

Example 27 except for using a polarizing film (SKN18242P, manufactured by Polar Techno Co., Ltd., of which the thickness of the polarizing film is 180 µm) instead of the wide viewing angle polarizing film which is one example of the optical film of the present invention described in Example 27. By the same operation as described above, when the respective absorption axes were arranged to be orthogonal, the light leakage state was evaluated at a position inclined at about 50 ° from the front direction in the direction of 45 ° orientation from each absorption axis. As a result, light leaked as it inclined from the front direction in the direction of 45 degrees from each absorption axis, and the viewing angle characteristic was inferior.

Comparative Example 6

A liquid crystal display device was produced in the same manner as in Example 32, except that a polarizing film (SKN18243T, manufactured by Polar Techno Co., Ltd.), which sandwiched both sides of the polarizing element with a triacetyl cellulose film, was also used for the observation surface side. When the liquid crystal display device was evaluated in the same manner as in the thirty-second embodiment, light leaked rapidly from the vicinity of the inclined position by about 40 degrees, so that the black state could not be maintained.

Comparative Example 7

A triacetyl cellulose film (manufactured by Fuji Photographic Film, TD80UF, thickness of about 80 μm) was uniaxially stretched in the same manner as in Example 1 until the original 1.8 times the length at 210 ° C. The thickness of the obtained retardation film was 77 micrometers, and the retardation value was measured like Example 1, and the retardation value in 590 nm was 77 nm. Moreover, the refractive index of the obtained retardation film was nx = 1.4875, ny = 1.4885, and nz = 1.4874. Moreover, when this film was refine | purified and the plasticizer and the ultraviolet absorber were removed, and substitution degree was computed by operation similar to Example 1, substitution degree was 2.9.

Comparative Example 8

Instead of the optical film of the present invention of Example 34, except that two polarizing films (SKN18243T, manufactured by Polar Techno Co., Ltd.) sandwiching both sides of the polarizing element with triacetyl cellulose films were used, respectively by the same operation as in Example 34, The leakage state of light when the absorption axes of the polarizing elements were arranged to be perpendicular to each other was evaluated. As a result, it was found that light was almost leaked, and the effect of blocking light was greatly reduced.

Comparative Example 9

A liquid crystal display device was produced in the same manner as in Example 36, except that a polarizing film (SKN18242P, manufactured by Polar Techno Co., Ltd.) was used instead of the wide viewing angle polarizing film which is one example of the optical film of the present invention obtained in Experimental Example 36. . When the liquid crystal display device was evaluated in the same manner as in Example 36, light leaked out due to the inclination, so that the black state could not be maintained.

Comparative Example 10

Retardation film made of uniaxially stretched polycarbonate used in Comparative Example 5 in a polarizing film (SKN18242P, manufactured by Polar Techno Co., Ltd.) in which two polarizing elements were sandwiched with three triacetyl cellulose films (phase direction of the retardation film) ) And the absorption axis of the polarizing element (stretching direction of the polarizing element) are parallel to each other, and then the phase difference value in the front direction of the film at 550 nm used in Example 31 is almost 0 nm, thickness is 50 µm, and Rth is almost 120. The film which adhere | attached nm retardation film (the Sekisui Chemical Co., Esshina) which is nm to the polycarbonate retardation plate side with the acrylic adhesive was produced. The thickness of this whole film was 345 micrometers. This film was used also for the observation surface side, and the liquid crystal display device was produced by operation similar to Example 35. FIG. When the liquid crystal display device was evaluated in the same manner as in Example 35, light leaked out due to the inclination, and thus a black state could not be maintained.

In FIG. 1, when Examples 1 and 2 and Comparative Example 7 are compared, the retardation film of Comparative Example 7 has an acromatic property, whereas the retardation film of the present invention is nx> ny> nz while ny> nx> nz. It turns out that it is a retardation film which has an achromatic property. In addition, it can be seen from the results of Examples 23 and 24 and Comparative Example 3 that the circular polarizing film of the present invention has an excellent antireflection effect. In addition, it can be seen from the results of Example 28 that the circularly polarizing film using the composite retardation film of the present invention not only has an excellent antireflection effect but also improves viewing angle characteristics. In addition, the results of Example 33 show that the viewing angle characteristic of the liquid crystal display device using the composite optical film of the present invention is greatly improved as compared with Comparative Example 6. In addition, the retardation film of the present invention obtained in Examples 3 to 7 has a biaxial property of nz≥ny> nx or ny> nz> nx despite being produced by uniaxial stretching, and also has a wavelength dispersion characteristic. It is understood that the phase difference value on the long wavelength side is smaller than the phase difference value at 550 nm than 550 nm, and the phase difference value on the short wavelength side is larger than the phase difference value at 550 nm than 550 nm. Moreover, it turns out that the viewing angle dependence of a polarizing film is significantly improved by using the optical film of this invention by the comparison of Example 34 and the comparative example 8. Furthermore, as can be seen from Examples 24, 28, and 34, the retardation film of the present invention can be laminated directly through a polarizing element and an adhesive by saponification treatment, and can also have a support of a polarizing film, thus providing a conventional polarization. The total thickness after lamination | stacking can be made thinner compared with adhesion | attachment with the adhesive with the polarizing film and the retardation film which hold | maintain both sides of an element by a support film.

Moreover, the phase difference film of this invention synthesize | combined in Examples 8-10 and obtained from the cellulose derivative of this invention produced in Examples 11-13 is 160 degreeC compared with Example 8 as shown in Examples 19-21. The film does not melt even when heated to, and since the large heat absorption peak generated at the time of melting cannot be seen at 200 ° C. or lower with a differential scanning calorimeter, it is understood that the heat resistance is improving. Moreover, it turns out that it is also possible to set it as the retardation film which has little change of the retardation value when it inclines, and has the outstanding viewing angle characteristic from the inclination phase difference ratio curve of FIG. In addition, as shown in Examples 25, 27, 31, and 35, the retardation film of the present invention can be adhered to the polarizing element by saponification treatment, which is significantly thinner as compared with Comparative Examples 4, 5 and 10. Moreover, it turns out that viewing angle characteristic is improving. Thus, by using the retardation film of this invention, an ellipse, a circle, or optical film, a wide viewing angle polarizing film, or an optical film excellent in thinness and heat resistance can be obtained, and each display apparatus using these films is thin, High heat resistance and excellent viewing angle characteristics can be given.

Moreover, it turns out that the retardation film which consists of the cellulose derivatives of this invention obtained in Example 18 is excellent in film strength compared with Example 41 as shown in Example 22. Moreover, it turns out that the retardation film which consists of the cellulose derivative of this invention obtained in Example 18 does not have coloring as shown in the comparative example 2, and is excellent in transparency. Moreover, as shown in Example 30, it turns out that the viewing angle characteristic of the optical film obtained from the retardation film of this invention is improving. Moreover, as shown in Example 36, it turns out that the viewing angle characteristic is improving in the liquid crystal display device provided with the retardation film of this invention compared with the comparative example 9. As described above, by using the retardation film of the present invention, the film strength can be improved and an optical film excellent in transparency can be obtained, and each display device using these films can provide excellent viewing angle characteristics.

Claims (26)

Nx> ny> nz or nz≥ny> nx or ny> nz> nx formed by uniaxial stretching of the film which consists of a cellulose derivative substituted by the acyl group of 5-20 carbon atoms of cellulose (refractive index of nx, The phase difference film whose refractive index of the direction orthogonal to it is ny, and the refractive index of the thickness direction is zn). Nx> ny> nz (index of refraction in the stretching direction is nx, which is obtained by uniaxially stretching a film made of a cellulose derivative having a degree of substitution of 2.0 to 2.8 in which a hydroxyl group of cellulose is substituted by an n-pentanoyl group). And a refractive index in a direction orthogonal to and in-plane orthogonal to each other, and a refractive index in the thickness direction is zn), and a wavelength dispersion characteristic has an achromatic property. Nx> ny> nz (index of refraction in the stretching direction is nx, which is obtained by uniaxially stretching a film made of a cellulose derivative having a degree of substitution of 2.0 to 2.5 in which a hydroxyl group of cellulose is substituted by an n-hexanoyl group). And a refractive index in the direction orthogonal to and in-plane orthogonal to each other, and a refractive index in the thickness direction is zn), and a wavelength dispersion characteristic has an achromatic property. The nz≥ny> nx or ny> nz> nx according to claim 1, wherein the hydroxyl group of the cellulose is uniaxially stretched by a film made of a cellulose derivative substituted with a linear acyl group having 7 to 20 carbon atoms. The refractive index is nx, the refractive index in the direction orthogonal to it is ny, the refractive index in the thickness direction is zn), and the wavelength dispersion characteristic is smaller than the phase difference value at the longer wavelength side than 550 nm, The retardation film on the short wavelength side is larger than the retardation value in 550 nm rather than 550 nm, The retardation film characterized by the above-mentioned. The retardation film of Claim 4 whose substitution degree of the C7 linear acyl group is 2.7-3.0. The retardation film of Claim 4 whose substitution degree of a C8-C20 linear acyl group is 2.0-3.0. The aliphatic acyl group according to any one of claims 1 to 6, which has a substituent different from the acyl group, the degree of substitution of the aliphatic acyl group having 5 to 20 carbon atoms is 2.00 or more, and the sum with other number of substituents. Ny> nz> nx or nz≥ny> nx which uniaxially stretches the film which consists of 2.50-3.0 cellulose derivatives per this cellulose monomer unit (refractive index of extending | stretching direction is nx, and the direction orthogonal to it in-plane is ny and the retardation film whose refractive index of the thickness direction is zn). The degree of substitution of a hydroxyl group by an aliphatic acyl group having 8 to 20 carbon atoms according to claim 1, wherein the three-dimensional refractive index at the measurement wavelength of 590 nm satisfies the following formula (1), and the heat resistance is 110 ° C or higher. Retardation film formed by extending | stretching the cellulose derivative which is 1.0 or more and less than 2.9 per monocellulose unit. ny> nx (1) In said Formula (1), nx is the refractive index of the extending direction in retardation film surface, and ny is the refractive index of the extending direction and orthogonal direction in retardation film surface. The retardation film of Claim 8 which extend | stretches the cellulose derivative which has at least 1 or more functional groups which can react with the remaining hydroxyl group of a cellulose derivative, and is bridge | crosslinked by the aliphatic compound which has a crosslinkable functional group. The retardation film according to claim 8 or 9, wherein the retardation ratio of the retardation film measured at a measurement wavelength of 590 nm satisfies the following formula (2). 0.5≤R (50) / R (0) ≤1.1 (2) In the above formula (2), R (50) is a retardation value when the retardation film is viewed from the front side inclined by 50 ° in the phase traveling axis direction, and R (0) is a retardation value when the retardation film is viewed from the front. to be. The composite retardation film which laminated | stacked the retardation film of any one of Claims 1-10, and another retardation film. A circular or elliptical polarizing film or optical film formed by laminating the retardation film or composite retardation film according to any one of claims 1 to 10 and a polarizing film. The optical film formed by laminating | stacking so that the phase retardation axis of the retardation film as described in any one of Claims 1-10, and the absorption axis or transmission axis of a polarizing film may become parallel or orthogonal. When the average refractive index in the film plane is no and the refractive index in the thickness direction is ne, when ne-no <0 and the thickness is d, Rth calculated as Rth = (no-ne) x d is 100 to 300 nm, The film whose phase difference value in the film front direction in 550 nm is 0-50 nm, the retardation film of any one of Claims 1-10, and a polarizing film are laminated | stacked one by one, and also the phase retardation of this retardation film Composite optical film laminated so that the axis and the absorption axis of the polarizing element perpendicular to each other. The polarizing element which comprises a polarizing film and the retardation film of any one of Claims 1-10 are laminated | stacked directly, The circular or elliptical polarization of any one of Claims 11-14 characterized by the above-mentioned. Film or optical film or optical film or composite optical film. An image display device comprising the circle or elliptical polarizing film or optical film or optical film or composite optical film according to any one of claims 11 to 14. 17. An image display apparatus according to claim 16, wherein the image display apparatus is a liquid crystal display apparatus. The three-dimensional refractive index at the measurement wavelength of 590 nm satisfies the following formula (1), and the substitution degree of the hydroxyl group by the aliphatic acyl group having 7 to 20 carbon atoms is 1.0 or more and less than 2.9 per cellulose monomer per cellulose ester. A retardation film formed by stretching a cellulose derivative having at least one functional group capable of reacting and crosslinked with an aliphatic compound having a crosslinkable functional group. ny> nx (1) In said formula (1), nx is the refractive index of the extending direction in retardation film surface, and ny is the refractive index of the extending direction and orthogonal direction in retardation film surface. The retardation film according to claim 18, wherein the retardation ratio of this retardation film measured at a measurement wavelength of 590 nm satisfies the following formula (2). 0.5 ≤ R (50) / R (0) ≤ 1.1 (2) In the above formula (2), R (50) is a retardation value when the retardation film is viewed from the front inclined by 50 ° in the phase advancing axis direction, and R (0) is a retardation when the retardation film is viewed from the front. Value. The retardation film according to claim 18, wherein the tear strength is 400 kg / cm 2 or more. The composite retardation film which laminated | stacked the retardation film of Claim 18 and another retardation film. The optical film which laminated | stacked the polarizing film on the retardation film of Claim 18, or the composite retardation film which laminated | stacked this retardation film and another retardation film. The liquid crystal display device provided with the retardation film, composite retardation film, or optical film in any one of Claims 18-22. A compound obtained by reacting an isocyanate group of an aliphatic compound having an isocyanate group with a (meth) acryloyl group, and reacting the isocyanate group of the aliphatic compound having an isocyanate group with a (meth) acryloyl group. Retardation film which is a cellulose derivative bridge | crosslinked by superposition | polymerization of a (meth) acryloyl group. The retardation film of Claim 24 whose aliphatic compound which has an isocyanate group and a (meth) acryloyl group is (meth) acryloyloxy C1-C20 aliphatic hydrocarbon isocyanate. The cellulose ester obtained by making (meth) acryloyloxy C1-C20 aliphatic hydrocarbon isocyanate react with the cellulose ester whose substitution degree of the hydroxyl group by C7-C20 aliphatic acyl group is 1.0 or more and less than 2.9 per cellulose monomer.

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