JPWO2008099731A1 - Polarizing plate and liquid crystal display device - Google Patents

Abstract

At least a first protective film, a polarizing film, a second protective film made of a thermoplastic polymer containing a cycloolefin resin, and the orientation of the rod-like liquid crystal aligned substantially perpendicular to the surface of the second protective film The fixed retardation layer is a polarizing plate arranged in this order, and Ro and Rt at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH of the second protective film and the retardation layer are respectively , Second protective film: Ro: 30 to 115 nm; Rt: 100 to 250 nm; and Rt / Ro: 1.6 to 4.4, retardation layer: Ro: 0 to 10 nm; and Rt: −100 to −400 nm The wavelength dispersion characteristic represented by the following formula 1 of the laminate of the second protective film and the retardation layer is 2.0 to 6.5 nm. Formula 1: D (R40) = R40 (630) −R40 (480) (wherein R40 represents a retardation value measured by tilting the slow axis in the plane of the sample by 40 ° about the rotation axis (630). (480) is the measurement wavelength (nm).)

Description

  The present invention relates to a polarizing plate and a liquid crystal display device, and more particularly to a polarizing plate suitable for a transverse electric field switching mode type liquid crystal display device, a polarizing plate with reduced color change when the viewing angle is changed, and a liquid crystal using the same The present invention relates to a display device.

  The transverse electric field switching mode type liquid crystal display device is excellent in color, contrast, viewing angle and the like in the liquid crystal mode of other liquid crystal display devices, for example, the TN mode, and in the vertical alignment mode (VA, MVA, PVA, etc.). On the other hand, it is excellent in display performance such as viewing angle, and also has excellent effects such as less luminance change due to viewing angle and less drop in response speed in halftone, so-called IPS (In Plane Switching) mode type liquid crystal display device As it came to be actively offered to the market. Examples of the IPS mode type liquid crystal display device include an FFS (fringe field switching) mode and an FLC (ferroelectric liquid crystal) mode in addition to the so-called IPS mode.

  Conventionally, the IPS system has a feature that a liquid crystal cell itself does not need to be compensated, and a wide viewing angle can be obtained without a compensation film (see, for example, Patent Document 1).

  However, when the polarizing plate used in the liquid crystal display device changes the viewing angle in the crossed Nicols state in the direction of 45 ° with respect to the absorption axis, light leakage occurs, thereby reducing the peripheral contrast of the liquid crystal display device. Is happening.

Therefore, for example, a form in which an optical film as in Patent Document 2 is laminated on a polarizing plate to suppress light leakage of the polarizing plate has been devised. However, in these methods, it cannot be said that the color change when the viewing angle is changed is sufficiently improved.
JP 2000-131700 A JP 2006-126770 A

  Accordingly, an object of the present invention is to provide a polarizing plate suitable for a horizontal electric field switching mode type liquid crystal display device, and to provide a polarizing plate with reduced color change when the viewing angle is changed, and a liquid crystal display device using the same. It is in.

One aspect of the present invention for achieving the above object is that at least a first protective film, a polarizing film, a second protective film made of a thermoplastic polymer containing a cycloolefin resin, and the second protective film. A retardation film in which the orientation of a rod-like liquid crystal that is aligned substantially perpendicular to the surface of the protective film is fixed in this order is a polarizing plate, wherein the second protective film and the retardation layer of 23 ° C. In the environment of 55% RH, the retardations Ro and Rt represented by Formulas 2 and 3 at a wavelength of 590 nm are respectively
Second protective film: Ro: 30 to 115 nm
Rt: 100 to 250 nm
Rt / Ro: 1.6 to 4.4
Retardation layer: Ro: 0 to 10 nm
Rt: −100 to −400 nm, and the wavelength dispersion characteristic represented by the following formula 1 of the laminate of the second protective film and the retardation layer is 2.0 to 6.5 nm. It is in the polarizing plate.

Formula 1: D (R40) = R40 (630) -R40 (480) (where R40 is a sample placed on a horizontal plane, tilted by 40 ° with the slow axis in the sample plane as the rotation axis, and in the perpendicular direction) (Measured retardation value is represented. (630), (480) represents each measured wavelength (nm).)
Formula 2: Ro = (nx−ny) × d
Formula 3: Rt = ((nx + ny) / 2−nz) × d (wherein the in-plane slow phase of the second protective film or the retardation layer or the laminate of the second protective film and the retardation layer) (The refractive index in the axial direction is nx, the refractive index in the direction orthogonal to the slow axis in the plane is ny, the refractive index in the thickness direction is nz, and d represents each thickness (nm).)

It is the schematic showing the measuring method of R40. It is a schematic diagram which shows the structure of the polarizing plate and liquid crystal display device of this invention. It is a schematic diagram of the tenter apparatus of the left-right independent control preferable for this invention.

  The above object of the present invention is achieved by the following configurations.

1. At least a first protective film, a polarizing film, a second protective film made of a thermoplastic polymer containing a cycloolefin resin, and the orientation of the rod-like liquid crystal aligned substantially perpendicular to the surface of the second protective film The fixed retardation layer is a polarizing plate arranged in this order, and the second protective film and the retardation layer are in the environment of 23 ° C. and 55% RH in the equations 2 and 3 at a wavelength of 590 nm. Retardation Ro and Rt represented are respectively
Second protective film: Ro: 30 to 115 nm
Rt: 100 to 250 nm
Rt / Ro: 1.6 to 4.4
Retardation layer: Ro: 0 to 10 nm
Rt: −100 to −400 nm, and the wavelength dispersion characteristic represented by the following formula 1 of the laminate of the second protective film and the retardation layer is 2.0 to 6.5 nm. Polarizing plate.

Formula 1: D (R40) = R40 (630) -R40 (480) (where R40 is a sample placed on a horizontal plane, tilted by 40 ° with the slow axis in the sample plane as the rotation axis, and in the perpendicular direction) (Measured retardation value is represented. (630), (480) represents each measured wavelength (nm).)
Formula 2: Ro = (nx−ny) × d
Formula 3: Rt = ((nx + ny) / 2−nz) × d (wherein the in-plane slow phase of the second protective film or the retardation layer or the laminate of the second protective film and the retardation layer) (The refractive index in the axial direction is nx, the refractive index in the direction orthogonal to the slow axis in the plane is ny, the refractive index in the thickness direction is nz, and d represents each thickness (nm).)
2. The polarizing plate according to 1 and two glass substrates that are disposed so as to sandwich a liquid crystal cell and have a rubbing axis in the same direction, and the orientation direction of liquid crystal molecules is aligned with the rubbing axis during black display. The polarizing plate according to claim 1, further comprising: a liquid crystal cell that is substantially parallel; a polarizing plate composed of a third protective film, a second polarizing film, and a fourth protective film in this order; The in-plane slow axis of the second protective film of the plate and the alignment direction of the liquid crystal molecules are substantially parallel, and the third protective film is Ro: 0 to 5 nm, Rt: −10 to 10 nm. Further, the liquid crystal display device, wherein the thickness of the third protective film is 20 to 45 μm.

  3. The polarizing plate according to 1 and two glass substrates that are disposed so as to sandwich a liquid crystal cell and have a rubbing axis in the same direction. The polarizing plate according to claim 1, comprising a liquid crystal cell that is substantially parallel, a polarizing plate constituted by a third protective film, a second polarizing film, and a fourth protective film in this order. The in-plane slow axis of the second protective film of the plate and the alignment direction of the liquid crystal molecules are substantially perpendicular, and the third protective film is Ro: 0 to 5 nm, Rt: −10 to 10 nm, Further, the liquid crystal display device, wherein the thickness of the third protective film is 20 to 45 μm.

  4). 4. The polarizing plate according to any one of 1 to 3, wherein the retardation layer is formed using a polymerizable liquid crystal material.

  5. 5. The polarizing plate as described in 4 above, wherein the polymerizable liquid crystal material is a polymerizable monomer.

  According to the present invention, it is possible to provide a polarizing plate suitable for a horizontal electric field switching mode type liquid crystal display device, in which a color change when a viewing angle is changed is reduced, and a liquid crystal display device using the polarizing plate.

  The best mode for carrying out the present invention will be described in detail below, but the present invention is not limited thereto.

  As a result of intensive studies on the above problems, the present inventors have found that in a transverse electric field switching mode type (also referred to as IPS mode type) liquid crystal display device, the wavelength dispersion characteristics of the retardation of the retardation plate, particularly the retardation in the film thickness direction. It has been confirmed that controlling the chromatic dispersion characteristics of the image has a great effect on the color change when the viewing angle is changed. It has come. The second protective film functioning as a retardation film contains a cycloolefin resin. However, the cycloolefin resin has a small photoelastic coefficient, and particularly in the application of a large panel such as an IPS mode type TV, the tensile stress. And corner irregularities that appear white in the four corners of the display device, which are likely to occur in tests and durability tests.

Accordingly, the polarizing plate for a transverse electric field switching mode type liquid crystal display device of the present invention comprises at least a first protective film, a polarizing film, a second protective film made of a thermoplastic polymer containing a cycloolefin resin, A retardation film in which the orientation of a rod-like liquid crystal that is aligned substantially perpendicular to the surface of the second protective film is fixed in this order is the polarizing plate, and the second protective film and the retardation layer Retardations Ro and Rt represented by Formulas 2 and 3 at a wavelength of 590 nm in an environment of 23 ° C. and 55% RH are
Second protective film: Ro: 30 to 115 nm
Rt: 100 to 250 nm
Rt / Ro: 1.6 to 4.4
Retardation layer: Ro: 0 to 10 nm
Rt: −100 to −400 nm, and the wavelength dispersion characteristic represented by the following formula 1 of the laminate of the second protective film and the retardation layer is 2.0 to 6.5 nm. To do.

Formula 1: D (R40) = R40 (630) -R40 (480) (where R40 is a sample placed on a horizontal plane and tilted by 40 ° with the slow axis in the sample plane as the rotation axis (tilt axis)). Retardation values measured in the perpendicular direction are represented by (630) and (480) represent respective measurement wavelengths (nm).
Formula 2: Ro = (nx−ny) × d
Formula 3: Rt = ((nx + ny) / 2−nz) × d (wherein the in-plane slow phase of the second protective film or the retardation layer or the laminate of the second protective film and the retardation layer) (The refractive index in the axial direction is nx, the refractive index in the direction orthogonal to the slow axis in the plane is ny, the refractive index in the thickness direction is nz, and d represents each thickness (nm).)
In order to set the retardation of the second protective film within the above numerical range, the second protective film is preferably stretched in the biaxial direction in a state where the film is heated. In addition, when the film containing the cycloolefin resin is stretched by heat treatment, in order to reduce the residual strain as much as possible, the glass transition point is in the range of −20 to + 30 ° C. The film is stretched about 10 times in the transport direction and in the direction orthogonal to the transport direction. When the film containing the cycloolefin resin is stretched in the direction perpendicular to the film transport direction, the value of Ro increases, and when the film is stretched in the transport direction, the value of Ro decreases and Rt increases. A preferable retardation value can be obtained by adjusting the draw ratio. Or it is preferable to stretch | stretch the film produced by the solution casting about 1.2 to 8 times in the direction orthogonal to a conveyance direction in the state with the residual solvent amount remaining about 2-100 mass%. In order to set the retardation of the retardation layer within the above range, Ro can be achieved by substantially vertically aligning liquid crystal molecules. In order to achieve the substantially vertical alignment of the liquid crystal material, it can be achieved by adjusting the surfactant, the heat treatment temperature after the solvent drying (alignment treatment temperature), the heat treatment time (alignment treatment time), and the alignment film. . However, since the pretilt angle between the liquid crystal material and the air interface reaches the substrate side, a special alignment film may not be required. Rt can be adjusted by controlling the thickness of the retardation layer and selecting a liquid crystal material.

  Moreover, in order to make retardation D (R40) in the state which laminated | stacked the said 2nd protective film and the said phase difference layer into the said numerical value range, in the surface of the sample of a 2nd protective film and a phase difference layer It is necessary to adjust the chromatic dispersion of the retardation value measured by tilting the slow axis of the rotation axis by 40 °. However, generally, the wavelength dispersion of the retardation of the cycloolefin film is smaller than the wavelength dispersion of the retardation of the liquid crystal material. Therefore, setting D (R40) within the above numerical range can be achieved by adjusting the wavelength dispersion of retardation of the retardation layer. The retardation dispersion of the retardation layer can be achieved by adjusting the thickness of the retardation layer and selecting a liquid crystal material.

  Further, it is preferable that the retardation of the retardation layer in the oblique direction is controlled by selecting the thickness of the retardation layer or selecting a liquid crystal material. Reducing the phase difference in the oblique direction can be achieved by reducing the film thickness or reducing Δn of the liquid crystal material.

  Further, the liquid crystal display device of the present invention according to the above 2 and 3 is substantially parallel to the glass substrate of the liquid crystal cell in the black display which is a feature of the polarizing plate of the present invention and the IPS mode liquid crystal cell. A liquid crystal cell in which liquid crystal molecules are aligned and the alignment directions of the respective liquid crystal molecules are substantially parallel to each other, and a polarizing plate constituted by a third protective film, a second polarizing film, and a fourth protective film The in-plane slow axis of the second protective film of the polarizing plate according to the above 1 and the alignment direction of the liquid crystal cell are substantially parallel or orthogonal, and the third protective film is Ro: The lateral electric field switching mode type liquid crystal display device is characterized in that 0 to 5 nm, Rt: −10 to 10 nm, and the thickness of the third protective film is 20 to 45 μm.

  That is, the retardation of the second protective film and the retardation layer is controlled within a specific range, and the retardations Ro and Rt of the third protective film are further reduced to reduce the thickness, whereby a lateral electric field switching mode type liquid crystal ideographic device. In addition to the effect of widening the viewing angle, the change in color can be greatly suppressed. Conventionally, the change in color at the time of black display has been remarkable, but this can be greatly reduced.

  In order to set the retardation of the third protective film within the above numerical range, if the third protective film is a cellulose ester film, it is manufactured by melt film formation or by solution film formation. In this case, it is preferable to maintain the glass transition temperature at a temperature equal to or higher than the glass transition point for 15 seconds or more, or to add an additive having a birefringence expression opposite to that of the cellulose ester. Moreover, if it is a cycloolefin resin-type film, it is preferable to use as it is, without performing the extending | stretching process, the film manufactured by melting or solution casting.

  Hereinafter, the present invention will be described in detail for each element.

<Measurement of retardation>
The measurement of retardation in the present invention can be performed at 590 nm or a predetermined wavelength (480 nm, 630 nm) in an environment of 23 ° C. and 55% RH using KOBRA 21ADH manufactured by Oji Scientific Instruments as an example. Moreover, when calculating retardation, the value which measured the refractive index of the applicable wavelength of each sample using Abbe's refractometer 1T (made by Atago Co., Ltd.) is used. In the case of a laminate, the average refractive index of each layer is used. For the film thickness d (nm), a commercially available micrometer is used to measure the thickness of the sample at several points, and an average value is used.

  Of the retardation (Ro, Rt, R40) of the laminate of the second protective film and the retardation layer in the present invention, when calculating R40, the in-plane slow axis of the laminate placed on the horizontal plane is Using the rotation axis as a rotation axis, the retardation when the laminate is inclined by 40 ° is measured in the perpendicular direction and used for calculation. The measurement principle of R40 is shown in FIG.

<Configuration of polarizing plate and liquid crystal display device>
The configuration of the polarizing plate and the liquid crystal display device of the present invention will be described with reference to the drawings.

  FIG. 2A. Is the configuration of the polarizing plate and the liquid crystal display device according to 2 above.

  A viewing-side polarizing plate is constituted by the first protective film 1, the first polarizing film 5, the second protective film 2, and the retardation layer 7 in which the orientation of the rod-like liquid crystal is fixed from the viewing side. It is bonded to the liquid crystal cell 8 sandwiched between the glass substrates 9 and 10. Further, a polarizing plate constituted by the third protective film 3, the second polarizing film 6, and the fourth protective film 4 is disposed on the surface opposite to the liquid crystal cell 8.

  The in-plane slow axis b of the second protective film and the alignment direction c of the liquid crystal cell are parallel. The polarizing transmission axis a of the polarizing film and the rubbing axis d of the glass substrate are in the directions shown in the figure. In the drawing, the retardation layer 7 may be disposed between the first polarizing film 5 and the second protective film 2.

  FIG. 2B. Is the configuration of the polarizing plate and the liquid crystal display device according to 3 above.

  A polarizing plate is constituted by the fourth protective film 4, the second polarizing film 6 and the third protective film 3 from the viewing side, and the polarizing plate is bonded to the liquid crystal cell 8 sandwiched between the glass substrates 9 and 10. The Further, on the surface opposite to the liquid crystal cell 8, a phase difference layer 7 in which the orientation of the rod-like liquid crystal is fixed, the second protective film 2, the first polarizing film 5, and the first protective film 1 are formed. A polarizing plate is disposed.

  The in-plane slow axis b of the second protective film and the alignment direction c of the liquid crystal cell are orthogonal. The polarizing transmission axis a of the polarizing film and the rubbing axis d of the glass substrate are in the directions shown in the figure. In the drawing, the retardation layer 7 may be disposed between the first polarizing film 5 and the second protective film 2.

<Retardation layer>
The polarizing plate of the present invention is obtained by applying a liquid crystal material (or liquid crystal solution) to a substrate, drying and heat treatment (also referred to as alignment treatment), fixing the liquid crystal alignment by ultraviolet curing or thermal polymerization, and the like. It is characterized by having a retardation layer made of a rod-like liquid crystal aligned vertically. The retardation layer is formed on the second protective film as a base material, or is formed on another base material, and is bonded to the second protective film. In this invention, it is preferable to form as a liquid-crystal layer on a 2nd protective film from the thin film formation of a polarizing plate and the ease of handling.

  The term “vertical alignment” as used herein refers to black when a liquid crystal alignment layer is sandwiched between crossed Nicol polarizers when evaluated using a polarizing microscope in order to evaluate the optical phase difference of the obtained liquid crystal alignment layer. Those that appear and appear white when the liquid crystal alignment layer is tilted between crossed Nicol polarizers are defined as vertically aligned.

  When forming the liquid crystal alignment layer, a so-called vertical alignment film may be used, and the vertical alignment film is not particularly limited. However, when the liquid crystal material itself is vertically aligned at the air interface, the alignment regulating force is the air interface. The alignment film is not particularly necessary when it extends to the interface opposite to that, and it is preferable from the viewpoint of simplifying the configuration. When using a vertical alignment film, it is also preferable to use an alignment film made of a cross-linked product of a block polymer composition containing a (meth) acrylic block polymer described in JP-A-2005-148473.

  The retardation layer according to the present invention is a retardation layer composed of substantially vertically aligned rod-like liquid crystals having Ro of 0 to 10 nm and Rt of -100 to -400 nm. Further, Ro is more preferably in the range of 0 to 5 nm. In order to make the retardation layer in the above range, it is preferable to control the thickness of the retardation layer, the temperature during ultraviolet curing, the tilt angle control, and the control of the pretilt angle at the support / air interface.

  The liquid crystal layer is formed by curing a liquid crystal material capable of forming a liquid crystal phase at a predetermined temperature with a predetermined liquid crystal regularity. The upper limit of the temperature showing the liquid crystal phase is not particularly limited as long as the transparent resin film of the base material is not damaged, for example. Specifically, a temperature of 120 ° C. or lower is preferable from the viewpoint of easy control of process temperature and maintenance of dimensional accuracy, and a liquid crystal material that becomes a liquid crystal phase at a temperature of 100 ° C. or lower is preferably used. On the other hand, the lower limit of the temperature showing the liquid crystal phase can be said to be a temperature at which the liquid crystal material can maintain the alignment state when used as a phase difference plate.

  As the liquid crystal material used as the retardation plate of the present invention, a polymerizable liquid crystal material is preferably used. The polymerizable liquid crystal material can be used by being polymerized by irradiating with predetermined actinic radiation. Since the alignment state is fixed in the polymerized state, the liquid crystal phase is used when the polymerizable liquid crystal material is used. The lower limit of the temperature is not particularly limited.

  As the polymerizable liquid crystal material, any of a polymerizable liquid crystal monomer, a polymerizable liquid crystal oligomer, and a polymerizable liquid crystal polymer can be used, and they can also be mixed with each other. Since the polymerizable liquid crystal material can fix the alignment state, the alignment of the liquid crystal can be easily performed at a low temperature, and the alignment state is fixed at the time of use. Can be used regardless of the usage conditions.

  Of the above, a polymerizable liquid crystal monomer is particularly preferably used as the polymerizable liquid crystal material. This is because the polymerizable liquid crystal monomer can be aligned at a lower temperature than the polymerizable liquid crystal oligomer and the polymerizable liquid crystal polymer and has high sensitivity at the time of alignment, so that it can be easily aligned.

  Specific examples of the polymerizable liquid crystal monomer include a rod-like liquid crystal compound (I) represented by the following general formula (1) and a rod-like liquid crystal compound (II) represented by the following general formula (2). be able to. As the compound (I), two or more compounds included in the general formula (1) can be mixed and used. Similarly, the compound (II) is included in the general formula (2). Two or more kinds of compounds may be mixed and used. In addition, one or more compounds (I) and one or more compounds (II) may be mixed and used.

In the general formula (1) representing the compound (I), R ¹ and R ² each represent hydrogen or a methyl group, but R ¹ and R ² are both hydrogen due to the wide temperature range showing the liquid crystal phase. preferable. X may be hydrogen, chlorine, bromine, iodine, an alkyl group having 1 to 4 carbon atoms, a methoxy group, a cyano group, or a nitro group, but is preferably chlorine or a methyl group. Moreover, a and b which show the chain length of the alkylene group which is a spacer with the (meth) acryloyloxy group of both ends of the molecular chain of a compound (I), and an aromatic ring are respectively arbitrary integers in the range of 2-12. Although it can take, it is preferable that it is the range of 4-10, and it is more preferable that it is the range of 6-9. The compound of the general formula (1) in which a = b = 0 is poor in stability, easily subjected to hydrolysis, and the compound itself has high crystallinity. In addition, the compound of the general formula (1) in which a and b are each 13 or more has a low isotropic transition temperature (TI). For this reason, both of these compounds are not preferred because the temperature range showing liquid crystallinity is narrow.

  Compound (I) can be synthesized by any method. For example, compound (I) wherein X is a methyl group can be obtained by an esterification reaction of 1 equivalent of methylhydroquinone and 2 equivalents of 4- (m- (meth) acryloyloxyalkoxy) benzoic acid. In the esterification reaction, the benzoic acid is usually activated with an acid chloride or a sulfonic anhydride, and this is reacted with methylhydroquinone. In addition, a carboxylic acid unit and methylhydroquinone can be reacted directly using a condensing agent such as DCC (dicyclohexylcarbodiimide). As other methods, esterification reaction of 1 equivalent of methylhydroquinone and 2 equivalents of 4- (m-benzyloxyalkoxy) benzoic acid is first performed, and then the resulting ester is debenzylated by hydrogenation reaction or the like. Then, compound (I) can also be synthesized by a method in which the molecular terminal is acryloylated. When performing esterification reaction of methylhydroquinone and 4- (m-benzyloxyalkoxy) benzoic acid, methylhydroquinone is introduced into diacetate and then reacted with the above benzoic acid in a molten state to obtain an ester directly. It is also possible. The compound (I) in the case where X in the general formula (1) is not a methyl group can also be obtained by performing the same reaction as above using hydroquinone having a corresponding substituent instead of methylhydroquinone.

In the general formula (2) representing the compound (II), R ³ represents hydrogen or a methyl group, but R ³ is preferably hydrogen because of the wide temperature range showing the liquid crystal phase. As for c indicating the chain length of the alkylene group, the compound (II) having this value of 2 to 12 does not exhibit liquid crystallinity. However, considering the compatibility with the compound (I) having liquid crystallinity, c is preferably in the range of 4 to 10, and more preferably in the range of 6 to 9. Compound (II) can also be synthesized by any method. For example, compound (II) can be synthesized by esterification reaction of 1 equivalent of 4-cyanophenol and 1 equivalent of 4- (n- (meth) acryloyloxyalkoxy) benzoic acid. II) can be synthesized. In the esterification reaction, the benzoic acid is generally activated with an acid chloride or a sulfonic acid anhydride and reacted with 4-cyanophenol, as in the case of synthesizing the compound (I). Moreover, you may make the said benzoic acid and 4-cyanophenol react using condensing agents, such as DCC (dicyclohexyl carbodiimide).

  In addition to the above, in the present invention, a polymerizable liquid crystal oligomer, a polymerizable liquid crystal polymer, or the like can be used. As such a polymerizable liquid crystal oligomer and a polymerizable liquid crystal polymer, those conventionally proposed can be appropriately selected and used.

  In the present invention, a photopolymerization initiator may be used as necessary in addition to the polymerizable liquid crystal material. When polymerizing a polymerizable liquid crystal material by electron beam irradiation, a photopolymerization initiator may not be necessary. However, in the case of curing by, for example, ultraviolet (UV) irradiation, which is generally used, photopolymerization is usually performed. This is because the initiator is used for promoting the polymerization.

  As photopolymerization initiators, benzyl (also called bibenzoyl), benzoin isobutyl ether, benzoin isopropyl ether, benzophenone, benzoylbenzoic acid, methyl benzoylbenzoate, 4-benzoyl-4'-methyldiphenyl sulfide, benzylmethyl ketal, dimethylamino Methylbenzoate, 2-n-butoxyethyl-4-dimethylaminobenzoate, isoamyl p-dimethylaminobenzoate, 3,3′-dimethyl-4-methoxybenzophenone, methylobenzoylformate, 2-methyl-1- (4 -(Methylthio) phenyl) -2-morpholinopropan-1-one, 2-benzyl-2-dimethylamino-1- (4-morpholinophenyl) -butan-1-one, 1- (4-dodecylphenyl) -2- Droxy-2-methylpropan-1-one, 1-hydroxycyclohexyl phenyl ketone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 1- (4-isopropylphenyl) -2-hydroxy-2- Examples include methylpropan-1-one, 2-chlorothioxanthone, 2,4-diethylthioxanthone, 2,4-diisopropylthioxanthone, 2,4-dimethylthioxanthone, isopropylthioxanthone, or 1-chloro-4-propoxythioxanthone. it can. In general, the addition amount of the photopolymerization initiator is preferably 0.01% to 20%, more preferably 0.1% to 10%, and still more preferably 0.5% to 5%. Can be added to the polymerizable liquid crystal material of the present invention. In addition to the photopolymerization initiator, a sensitizer can be added as long as the object of the present invention is not impaired.

  The film thickness of the liquid crystal layer in the present invention is preferably in the range of 0.1 μm to 20 μm, and more preferably in the range of 0.2 to 10 μm. When the liquid crystal layer of the present invention is thicker than the above range, an optical anisotropy more than necessary occurs, and when it is thinner than the above range, a predetermined optical anisotropy may not be obtained. Therefore, the thickness of the liquid crystal layer may be determined according to the optical anisotropy necessary for the present invention.

  A polymerizable liquid crystal material is prepared by using a composition for forming a liquid crystal layer by blending a photopolymerization initiator, a sensitizer, etc., if necessary, and coating on a substrate to form a liquid crystal layer forming layer. To do. As a method for forming a liquid crystal layer forming layer, for example, a method of laminating a liquid film layer forming layer on a substrate by previously forming a dry film or the like, or melting a liquid crystal layer forming composition However, in the present invention, the composition for forming a liquid crystal layer is a coating composition in which other components are dissolved by adding a solvent. It is preferable to form a liquid crystal layer forming layer by coating on a substrate and removing the solvent. This is simple in terms of process as compared with other methods.

  The solvent is not particularly limited as long as it is a solvent capable of dissolving the above-described polymerizable liquid crystal material and the like and does not deteriorate the properties of the transparent resin film. Specifically, benzene, Hydrocarbons such as toluene, xylene, n-butylbenzene, diethylbenzene, tetralin; ethers such as methoxybenzene, 1,2-dimethoxybenzene, diethylene glycol dimethyl ether; acetone, methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, or 2,4- Ketones such as pentanedione; ethyl acetate, ethylene glycol monomethyl ether acetate, propylene glycol monomethyl ether acetate, propylene glycol monoethyl ether acetate, or γ-butyrolactone Amides solvents such as 2-pyrrolidone, N-methyl-2-pyrrolidone, dimethylformamide, or dimethylacetamide; chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, tritrichloroethylene, tetrachloroethylene, chlorobenzene, or orthodichlorobenzene Halogen solvents such as t-butyl alcohol, diacetone alcohol, glycerin, monoacetin, ethylene glycol, triethylene glycol, hexylene glycol, ethylene glycol monomethyl ether, ethyl cellosolve, or butyl cellosolve; phenols, One or more of phenols such as parachlorophenol can be used.

  If only a single type of solvent is used, the solubility of the polymerizable liquid crystal material or the like may be insufficient, or the substrate may be eroded as described above. However, this inconvenience can be avoided by using a mixture of two or more solvents. Of the above-mentioned solvents, preferred as a single solvent are a hydrocarbon solvent and a glycol monoether acetate solvent, and a preferred mixed solvent is a mixed system of ethers or ketones and glycols. It is. The concentration of the solution depends on the solubility of the polymerizable liquid crystal material or the like and the film thickness of the liquid crystal layer to be produced, but cannot be defined unconditionally, but is usually preferably 1% to 60%, more preferably 3% to It is adjusted within the range of 40%.

  Compounds other than those described above can be added to the composition for forming a liquid crystal layer used in the present invention within a range not impairing the object of the present invention. Examples of compounds that can be added include polyester (meth) acrylate obtained by reacting (meth) acrylic acid with a polyester prepolymer obtained by condensing polyhydric alcohol and monobasic acid or polybasic acid; A polyurethane (meth) acrylate obtained by reacting a compound having two isocyanate groups with each other and then reacting the reaction product with (meth) acrylic acid; bisphenol A type epoxy resin, bisphenol F type epoxy resin, novolak Type epoxy resin, polycarboxylic acid polyglycidyl ester, polyol polyglycidyl ether, aliphatic or cycloaliphatic epoxy resin, amine epoxy resin, triphenolmethane type epoxy resin, dihydroxybenzene type epoxy resin and the like (meth) Ak Photopolymerizable compounds such as epoxy (meth) acrylate obtained by reacting le acid, or a photopolymerizable liquid crystal compound, and the like having an acrylic group or methacrylic group. The amount of these compounds added to the composition for forming a liquid crystal layer of the present invention is selected within a range that does not impair the purpose of the present invention, and is generally 40% or less of the composition for forming a liquid crystal layer of the present invention. Preferably, it is 20% or less. Addition of these compounds improves the curability of the liquid crystal material in the present invention, increases the mechanical strength of the resulting liquid crystal layer, and improves its stability.

  In addition, a surfactant or the like can be added to the composition for forming a liquid crystal layer containing a solvent in order to facilitate coating. Examples of surfactants that can be added include cationic surfactants such as imidazoline, quaternary ammonium salts, alkylamine oxides and polyamine derivatives; polyoxyethylene-polyoxypropylene condensates, primary or secondary Alcohol ethoxylates, alkylphenol ethoxylates, polyethylene glycol and esters thereof, sodium lauryl sulfate, ammonium lauryl sulfate, lauryl sulfate amines, alkyl-substituted aromatic sulfonates, alkyl phosphates, aliphatic or aromatic sulfonic acid formalin condensates, etc. Anionic surfactants; amphoteric surfactants such as laurylamidopropylbetaine and laurylaminoacetic acid betaine; nonionics such as polyethylene glycol fatty acid esters and polyoxyethylene alkylamine Surfactant: Perfluoroalkyl sulfonate, perfluoroalkyl carboxylate, perfluoroalkyl ethylene oxide adduct, perfluoroalkyl trimethyl ammonium salt, perfluoroalkyl group / hydrophilic group-containing oligomer, perfluoroalkyl / lipophilic group Fluorosurfactants such as containing oligomer perfluoroalkyl group-containing urethanes. The amount of surfactant added depends on the type of surfactant, the type of liquid crystal material, the type of solvent, and the type of alignment film on which the solution is applied. 10 ppm to 10% is preferable, more preferably 100 ppm to 5%, and still more preferably 0.1 to 1%.

  As a method for coating the composition for forming a liquid crystal layer, a spin coating method, a roll coating method, a printing method, a dip pulling method, a die coating method, a casting method, a bar coating method, a blade coating method, a spray coating method, a gravure coating method , Reverse coating method or extrusion coating method. The method for removing the solvent after coating the composition for forming a liquid crystal layer is performed, for example, by air drying, heat removal, or removal under reduced pressure, or a combination thereof. By removing the solvent, a liquid crystal layer forming layer is formed.

  In the step of curing the polymerizable liquid crystal material, energy for curing the polymerizable liquid crystal material is given, and thermal energy may be used, but it is usually performed by irradiation with ionizing radiation capable of causing polymerization. If necessary, a polymerization initiator may be contained in the polymerizable liquid crystal material. The ionizing radiation is not particularly limited as long as it is a radiation capable of polymerizing the polymerizable liquid crystal material, but usually ultraviolet light or visible light is used from the viewpoint of the ease of the apparatus, and the wavelength. Is preferably from 150 to 500 nm, more preferably from 250 to 450 nm, and even more preferably from 300 to 400 nm.

  In the present invention, a method of performing radical polymerization by irradiating ultraviolet rays (UV) as actinic radiation and generating radicals from the polymerization initiator with ultraviolet rays is preferable. Since the method using UV as the actinic radiation is an already established technique, it can be easily applied to the present invention including the polymerization initiator to be used.

  As a light source for irradiating ultraviolet rays, a low-pressure mercury lamp (sterilization lamp, fluorescent chemical lamp, black light), a high-pressure discharge lamp (high-pressure mercury lamp, metal halide lamp), or a short arc discharge lamp (ultra-high-pressure mercury lamp, xenon) Lamp, mercury xenon lamp) and the like. In particular, the use of metal halide lamps, xenon lamps, high-pressure mercury lamps, etc. is recommended. The irradiation intensity may be appropriately adjusted depending on the composition of the polymerizable liquid crystal material forming the liquid crystal layer and the amount of the photopolymerization initiator.

  The alignment fixing step by irradiation with actinic radiation may be performed at the processing temperature in the step of forming the liquid crystal layer forming layer described above, that is, the temperature condition in which the polymerizable liquid crystal material becomes a liquid crystal phase, It may be performed at a lower temperature. The polymerizable liquid crystal material once in a liquid crystal phase does not suddenly disturb the alignment state even if the temperature is lowered thereafter.

<< First to fourth protective films >>
As a base material used for the 1st-4th protective film which concerns on the said 1-3, it is preferable that it is easy to manufacture, optically transparent, etc., and it is especially preferable that it is a transparent resin film.

  The term “transparent” as used in the present invention means that the visible light transmittance is 60% or more, preferably 80% or more, and particularly preferably 90% or more.

<Second protective film>
First, the second protective film according to the present invention will be described.

  The second protective film is characterized by being made of a thermoplastic polymer containing a cycloolefin resin, and there is no particular limitation on the form thereof, but stability, ease of handling at the time of making a polarizing plate or display device, Therefore, a resin film is preferable. As described above, cycloolefin resin has a small photoelastic coefficient and moisture permeability, and particularly in the use of large panels such as IPS mode type TVs, the four corners of the display device that are likely to occur in tensile stress and durability tests appear white. Corner unevenness can be remarkably suppressed.

  The cycloolefin resin used in the present invention is composed of a polymer resin containing an alicyclic structure.

  A preferred cycloolefin resin is a resin obtained by polymerizing or copolymerizing a cyclic olefin. Examples of the cyclic olefin include norbornene, dicyclopentadiene, tetracyclododecene, ethyltetracyclododecene, ethylidenetetracyclododecene, tetracyclo [7.4.0.110, 13.02,7] trideca-2,4. Unsaturated hydrocarbons of polycyclic structures such as 6,11-tetraene and derivatives thereof; cyclobutene, cyclopentene, cyclohexene, 3,4-dimethylcyclopentene, 3-methylcyclohexene, 2- (2-methylbutyl) -1-cyclohexene, cyclo Examples thereof include monocyclic unsaturated hydrocarbons such as octene, 3a, 5,6,7a-tetrahydro-4,7-methano-1H-indene, cycloheptene, cyclopentadiene, cyclohexadiene, and derivatives thereof. These cyclic olefins may have a polar group as a substituent. Examples of the polar group include a hydroxyl group, a carboxyl group, an alkoxyl group, an epoxy group, a glycidyl group, an oxycarbonyl group, a carbonyl group, an amino group, an ester group, and a carboxylic acid anhydride group. Or a carboxylic anhydride group is preferred.

  Preferred cycloolefin resins may be those obtained by addition copolymerization of monomers other than cyclic olefins. Addition copolymerizable monomers include ethylene, propylene, 1-butene, 1-pentene and other ethylene or α-olefins; 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl- Examples include dienes such as 1,4-hexadiene and 1,7-octadiene.

The cyclic olefin is obtained by an addition polymerization reaction or a metathesis ring-opening polymerization reaction. The polymerization is carried out in the presence of a catalyst. Examples of the addition polymerization catalyst include a polymerization catalyst composed of a vanadium compound and an organoaluminum compound. As a catalyst for ring-opening polymerization, a polymerization catalyst comprising a metal halide such as ruthenium, rhodium, palladium, osmium, iridium, platinum, nitrate or acetylacetone compound and a reducing agent; or titanium, vanadium, zirconium, tungsten, molybdenum Examples thereof include a polymerization catalyst comprising a metal halide such as acetylacetone compound and an organoaluminum compound. The polymerization temperature, pressure and the like are not particularly limited, but the polymerization is usually carried out at a polymerization temperature of -50 ° C to 100 ° C and a polymerization pressure of 0 to 490 N / cm ² .

  The cycloolefin resin used in the present invention is preferably a resin obtained by polymerizing or copolymerizing a cyclic olefin, followed by a hydrogenation reaction to change the unsaturated bond in the molecule to a saturated bond. The hydrogenation reaction is performed by blowing hydrogen in the presence of a known hydrogenation catalyst. Examples of hydrogenation catalysts include cobalt acetate / triethylaluminum, nickel acetylacetonate / triisobutylaluminum, transition metal compounds such as titanocene dichloride / n-butyllithium, zirconocene dichloride / sec-butyllithium, tetrabutoxytitanate / dimethylmagnesium / alkyl. Homogeneous catalyst consisting of a combination of metal compounds; heterogeneous metal catalyst such as nickel, palladium, platinum; nickel / silica, nickel / diatomaceous earth, nickel / alumina, palladium / carbon, palladium / silica, palladium / diatomaceous earth And a heterogeneous solid-supported catalyst in which a metal catalyst such as palladium / alumina is supported on a carrier.

  Or the following norbornene-type polymer is also mentioned as a cycloolefin resin. The norbornene-based polymer preferably has a norbornene skeleton as a repeating unit. Specific examples thereof include JP-A-62-252406, JP-A-62-2252407, and JP-A-2-133413. JP-A-63-145324, JP-A-63-264626, JP-A-1-240517, JP-B-57-8815, JP-A-5-39403, JP-A-5-43663 JP-A-5-43834, JP-A-5-70655, JP-A-5-279554, JP-A-6-206985, JP-A-7-62028, JP-A-8-176411, Although what was described in Kaihei 9-241484 etc. can utilize preferably, it is not limited to these. Moreover, these may be used individually by 1 type and may use 2 or more types together.

  In the present invention, among the norbornene polymers, those having a repeating unit represented by any of the following structural formulas (I) to (IV) are preferable.

  In the structural formulas (I) to (IV), A, B, C and D each independently represent a hydrogen atom or a monovalent organic group.

  Among the norbornene-based polymers, a polymer obtained by metathesis polymerization of at least one compound represented by the following structural formula (V) or (VI) and an unsaturated cyclic compound copolymerizable therewith. A hydrogenated polymer obtained by hydrogenating is also preferred.

  In the structural formula, A, B, C and D each independently represent a hydrogen atom or a monovalent organic group.

  Here, A, B, C and D are not particularly limited, but preferably an organic group may be linked via a hydrogen atom, a halogen atom, a monovalent organic group, or at least a divalent linking group. These may be the same or different. A or B and C or D may form a monocyclic or polycyclic structure. Here, the at least divalent linking group includes a hetero atom typified by an oxygen atom, a sulfur atom, and a nitrogen atom, and examples thereof include ether, ester, carbonyl, urethane, amide, thioether, and the like. It is not limited. In addition, the organic group may be further substituted via the linking group.

  Examples of other monomers copolymerizable with the norbornene-based monomer include ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, 1-decene, 1-dodecene, 1-tetradecene, C2-C20 alpha olefins, such as 1-hexadecene, 1-octadecene, 1-eicocene, and derivatives thereof; cyclobutene, cyclopentene, cyclohexene, cyclooctene, 3a, 5,6,7a-tetrahydro-4,7 -Cycloolefins such as methano-1H-indene, and derivatives thereof; non 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 1,7-octadiene, etc. Conjugated dienes; and the like are used. Among these, an α-olefin, particularly ethylene is preferable.

  These other monomers copolymerizable with the norbornene-based monomer can be used alone or in combination of two or more. In the case of addition copolymerization of a norbornene monomer and another monomer copolymerizable therewith, the ratio of the structural unit derived from the norbornene monomer and the structural unit derived from the other monomer copolymerizable in the addition copolymer However, it is appropriately selected so that the mass ratio is usually 30:70 to 99: 1, preferably 50:50 to 97: 3, more preferably 70:30 to 95: 5.

  When the unsaturated bond remaining in the molecular chain of the synthesized polymer is saturated by a hydrogenation reaction, the hydrogenation rate is 90% or more, preferably 95% or more, particularly from the viewpoint of light resistance deterioration, weather resistance deterioration, etc. Preferably it is 99% or more.

  In addition, examples of the cycloolefin resin used in the present invention include thermoplastic saturated norbornene resins described in paragraphs [0014] to [0019] of JP-A-5-2108, and paragraph Nos. [0015] of JP-A-2001-277430. ] To [0031] thermoplastic norbornene polymers, JP 2003-14901 paragraph Nos. [0008] to [0045] thermoplastic norbornene resins, JP 2003-139950 paragraph Nos. [0014] to [0028] Norbornene-based resin composition, paragraph Nos. [0029] to [0037] described in JP-A No. 2003-161832, paragraph Nos. [0027] to [0036] described in JP-A No. 2003-195268 Norbornene resin, Japanese Patent Application Laid-Open No. 2003-211589 Paragraph Nos. [0009] to [0023] alicyclic structure-containing polymer resin, norbornene polymer resin or vinyl alicyclic hydrocarbon heavy as described in paragraph Nos. [0008] to [0024] of JP-A No. 2003-111588 Examples include coalesced resins.

  Specifically, ZEONEX, ZEONOR manufactured by Nippon Zeon Co., Ltd., Arton manufactured by JSR Corporation, APPEL manufactured by Mitsui Chemicals, Inc. (APL8008T, APL6509T, APL6013T, APL5014DP, APL6015T) and the like are preferably used.

  The molecular weight of the cycloolefin resin used in the present invention is appropriately selected according to the purpose of use, but was measured by a gel permeation chromatographic method of a cyclohexane solution (a toluene solution when the polymer resin does not dissolve). When the polyisoprene or polystyrene-equivalent weight average molecular weight is usually in the range of 5,000 to 500,000, preferably 8,000 to 200,000, more preferably 10,000 to 100,000, the mechanical strength and molding processability of the molded body are high. Balanced and suitable.

  Moreover, when a low-volatile antioxidant is blended at a ratio of 0.01 to 5 parts by mass with respect to 100 parts by mass of the cycloolefin resin, it can effectively prevent the polymer from being decomposed or colored during the molding process. I can do it.

As the antioxidant, an antioxidant having a vapor pressure at 20 ° C. of 10 ⁻⁵ Pa or less, particularly preferably 10 ⁻⁸ Pa or less is desirable. Antioxidants having a vapor pressure higher than 10 ⁻⁵ Pa cause foaming during extrusion molding, and the antioxidants volatilize from the surface of the molded product when exposed to high temperatures.

  As an antioxidant which can be used by this invention, the following can be mentioned, for example, You may use 1 type in combination of these or several types.

  Hintard phenol type: 2,6-di-t-butyl-4-methylphenol, 2,6-di-t-butylphenol, 4-hydroxymethyl-2,6-di-t-butylphenol, 2,6-di -T-butyl-α-methoxy-p-dimethyl-phenol, 2,4-di-t-amylphenol, t-butyl-m-cresol, 4-t-butylphenol, styrenated phenol, 3-t-butyl- 4-hydroxyanisole, 2,4-dimethyl-6-tert-butylphenol, octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 3,5-di-tert-butyl-4 -Hydroxybenzylphosphonate-diethyl ester, 4,4'-bisphenol, 4,4'-bis- (2,6-di-t-butylphenol), , 2'-methylene-bis- (4-methyl-6-t-butylphenol), 2,2'-methylene-bis- (4-methyl-6-α-methylcyclohexylphenol), 4,4'-methylene- Bis- (2-methyl-6-t-butylphenol), 4,4'-methylene-bis- (2,6-di-t-butylphenol), 1,1'-methylene-bis- (2,6-di -T-butylnaphthol), 4,4'-butylidene-bis- (2,6-di-t-butyl-meta-cresol), 2,2'-thio-bis- (4-methyl-6-t- Butylphenol), di-o-cresol sulfide, 2,2'-thio-bis- (2-methyl-6-tert-butylphenol), 4,4'-thio-bis (3-methyl-6-tert-butylphenol) 4,4'-thio-bis- (2, -Di-sec-amylphenol), 1,1'-thio-bis- (2-naphthol), 3,5-di-t-butyl-4-hydroxybenzyl ether, 1,6-hexanediol-bis- [ 3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate], 2,4-bis- (n-octylthio) -6- (4-hydroxy-3,5-di-tert-butylanilino) -1,3,5-triazine, 2,2-thio-diethylenebis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,2-thiobis (4-methyl-6) -T-butylphenol), N, N'-hexamethylenebis (3,5-di-t-butyl-4-hydroxy-hydrocinnamamide), bis (3,5-di-t-butyl-4-hydroxy) Benzylphospho Acid ethyl) calcium, 1,3,5-trimethyl-2,4,6-tris- (3,5-di-tert-butyl-4-hydroxybenzyl) benzene, triethylene glycol-bis [3- (3- t-butyl-5-methyl-4-hydroxyphenyl) propionate], 1,3,5-trimethyl-2,4,6, -tris (3,5-di-t-butyl-4-hydroxybenzyl) benzene, Tris- (3,5-di-t-butyl-4-hydroxybenzyl) -isocyanurate, pentaerythrityl-tetrakis [3- (3,5-di-t-butyl-4-hydroxygenyl) propionate], etc. .

  Aminophenols: normal butyl-p-aminophenol, normal butyroyl-p-aminophenol, normal peragonoyl-p-aminophenol, normal lauroyl-p-aminophenol, normal stearoyl-p-aminophenol, 2, 6 -Di-t-butyl-α-dimethyl, amino-p-cresol and the like.

  Hydroquinone series: hydroquinone, 2,5-di-t-butylhydroquinone, 2,5-di-t-amylhydroquinone, hydroquinone methyl ether, hydroquinone monobenzyl ether, and the like.

  Phosphite triphosphite, tris (3,4-di-t-butylphenyl) phosphite, tris (nonylphenyl) phosphite, tetrakis (2,4-di-t-butylphenyl) -4,4'-biphenylene Phosphanite, 2-ethylhexyl octyl phosphite, etc.

  Others: 2-mercaptobenzothiazole zinc salt, dicatechol borate-di-o-tolylguanidine salt, nickel-dimethyldithiocarbamate, nickel-pentamethylene dithiocarbanate, mercaptobenzimidazole, 2-mercaptobenzimidazole zinc salt and the like.

(Hindered amine stabilizer)
By adding a hindered amine stabilizer to the resin, it is possible to highly suppress changes in optical properties such as white turbidity and changes in refractive index when irradiated with light having a short wavelength of 400 nm. The content of the hindered amine stabilizer is preferably 0.05 to 2 parts by mass, and more preferably 0.1 to 1 part by mass with respect to 100 parts by mass of the resin.

  Preferred hindered amine stabilizers include bis (2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (2,2,6,6-tetramethyl-4-piperidyl) succinate, bis ( 1,2,2,6,6-pentamethyl-4-piperidyl) sebacate, bis (N-octoxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (N-benzyloxy-2, 2,6,6-tetramethyl-4-piperidyl) sebacate, bis (N-cyclohexyloxy-2,2,6,6-tetramethyl-4-piperidyl) sebacate, bis (1,2,2,6,6) -Pentamethyl-4-piperidyl) 2- (3,5-di-t-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1-acryloyl-2,2,6 6-tetramethyl-4-piperidyl) 2,2-bis (3,5-di-t-butyl-4-hydroxybenzyl) -2-butylmalonate, bis (1,2,2,6,6-pentamethyl) -4-piperidyldecane) dioate, 2,2,6,6-tetramethyl-4-piperidyl methacrylate, 4- [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyloxy] -1 -[2- (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionyloxy) ethyl] -2,2,6,6-tetramethylpiperidine, 2-methyl-2- (2, 2,6,6-tetramethyl-4-piperidyl) amino-N- (2,2,6,6-tetramethyl-4-piperidyl) propionamide, tetrakis (2,2,6,6-tetramethyl-4 -Pipette Jill) 1,2,3,4-butane tetracarboxylate, tetrakis (1,2,2,6,6-pentamethyl-4-piperidyl) 1,2,3,4-butane tetracarboxylate, and the like.

(Antistatic agent)
It is preferable that the cycloolefin resin film of this invention contains an antistatic agent, and it is preferable to contain 0.001-2.0 mass parts of antistatic agents with respect to 100 mass parts of resin.

  The antistatic agent is not particularly limited, and known antistatic agents can be used. Among them, anionic antistatic agents, cationic antistatic agents, nonionic antistatic agents, and zwitterionic antistatic agents can be used. Preferably at least one selected from an agent, a polymer antistatic agent and conductive fine particles, more preferably conductive fine particles, particularly preferably cerium oxide, indium oxide, tin oxide, antimony oxide and silicon oxide. At least one selected.

  Examples of the anionic antistatic agent include fatty acid salts, higher alcohol sulfate esters, liquid fatty oil sulfate esters, aliphatic amines and aliphatic amide sulfates, aliphatic alcohol phosphate esters, dibasic fatty acid esters. Sulfonic acid salts, aliphatic amide sulfonic acid salts, alkylallyl sulfonic acid salts, formalin-condensed naphthalene sulfonic acid salts, and the like. Examples of cationic antistatic agents include aliphatic amine salts and quaternary ammonium salts. And alkylpyridinium salts. Examples of nonionic antistatic agents include polyoxyethylene alkyl ethers, polyoxyethylene alkyl phenol ethers, polyoxyethylene alkyl esters, sorbitan alkyl esters, polyoxyethylene sorbitan alkyl esters, and the like. Examples of the ionic antistatic agent include imidazoline derivatives, betaine-type higher alkylamino derivatives, sulfate ester derivatives, phosphate ester derivatives, and the like. Specific compounds include “antistatic agent polymer surface” by Hideo Marumo. Modified "Koshobo, Augmented" Practical Handbook for Additives for Plastics and Rubbers p333-p455 "published by Chemical Industry Co., Ltd., JP-A-11-256143, JP-B-52-32572, JP-A-10-158484, etc. Yes.

  Preferable antistatic agents include ionic polymer compounds such as anionic antistatic agents and cationic antistatic agents. Examples of the ionic polymer compound include anionic polymer compounds such as those described in JP-B-49-23828, JP-A-49-23827, and JP-A-47-28937; JP-B-55-734, JP-A-50-54672 Ionene type polymers having a dissociating group in the main chain, as shown in JP-B Nos. 59-14735, 57-18175, 57-18176, 57-56059 and the like: JP-B 53-13223 No. 57-15376, No. 53-45231, No. 55-145783, No. 55-65950, No. 55-67746, No. 57-11342, No. 57-19735, No. 58-56858. No., JP-A-61-27853, 62-9346, and a cationic pendant type having a cationic dissociation group in the side chain. Mer, it can be mentioned graft copolymers, such as seen in JP-A-5-230161.

As the conductive fine particles that can be used particularly preferably in the present invention, examples of metal oxides include ZnO, TiO ₂ , SnO ₂ , Al ₂ O ₃ , In ₂ O ₃ , SiO ₂ , MgO, BaO, CeO ₂ , Sb ₂ O ₃ , MoO ₂ , V ₂ O ₅ , or the like, or a composite oxide thereof is preferable, and CeO ₂ , In ₂ O ₃ , SnO ₂ , Sb ₂ O ₃ , and SiO ₂ are particularly preferable. As an example of containing a heteroatom, the addition Al, or In to ZnO, addition Nb, or Ta for TiO _2, also for the SnO _2, Sb, Nb, halogen elements etc. Is effective. The amount of these different atoms added is preferably in the range of 0.01 to 25 mol%, particularly preferably in the range of 0.1 to 15 mol%.

  In the present invention, the average fine particle diameter of the conductive fine particles is preferably 100 nm or less, more preferably 5 to 100 nm. If the average fine particle diameter of the conductive fine particles is 100 nm or less, it is preferable since sufficient charging characteristics can be imparted when contained in the resin material and the transparency of the resin material is not impaired.

Particularly preferable antistatic agents are those having a surface resistivity of 1 × 10 ¹⁰ Ω or less from the relationship between the antistatic performance and the addition amount. The surface specific resistance value is measured according to ASTM D257 using a superinsulator after the sample is conditioned for 24 hours in an atmosphere of 23 ° C. and 50% RH.

  Antistatic agents that can be preferably used in the present invention are ionene conductive polymers described in JP-A-9-203810, quaternary ammonium cationic conductive polymers having intermolecular crosslinking, and the like.

  The characteristics of the cross-linked cationic conductive polymer are the dispersible granular polymer obtained, and the cationic component in the fine particles can be given a high concentration and high density. The compatibility with the resin is good, and high transparency is selected. Furthermore, no deterioration in conductivity is observed even under a low relative humidity.

  The dispersible granular polymer, which is a crosslinked cationic conductive polymer used for antistatic, is generally in the fine particle size range of about 0.01 to 0.3 μm, preferably in the range of 0.05 to 0.15 μm. Is used.

  In the present invention, each antistatic agent described above is preferably added in the range of 0.001 to 2.0 parts by mass with respect to 100 parts by mass of the cycloolefin resin, and the addition amount of the antistatic agent is 0. When the amount is 0.001 part by mass or more and 2.0 parts by mass or less, adhesion of dust and dust to the resin material can be effectively suppressed, and the light transmittance of the resin material can be maintained at a desired value. In addition, it is preferable that the addition amount of an antistatic agent is 0.005-1.0 mass part with respect to 100 mass parts of polymers which have an alicyclic structure, and 0.01-0.5 mass part is further. preferable.

  In the present invention, the same effect can be obtained by providing the resin with a layer containing the antistatic agent and a fluorine compound generally used for antifouling.

  In order to obtain the performance of the cycloolefin resin film of the present invention, a layer containing at least one antistatic agent (antistatic layer) may be provided on the film surface.

  The antistatic layer may be provided by applying a mixture containing the above-described antistatic agent to the surface of the optical element, or may be provided by a method such as vapor deposition. The antistatic layer preferably has a thickness of 50 μm or more and 300 μm or less.

(Other stabilizers)
One or more stabilizers selected from phenol-based stabilizers, phosphorus-based stabilizers, and sulfur-based stabilizers may be added to the resin. By appropriately selecting these stabilizers and adding them to the resin, it is possible to more highly suppress optical turbidity and white turbidity and refractive index fluctuations when irradiated with light having a short wavelength of 400 nm. .

  As a preferable phenol-based stabilizer, conventionally known ones can be used, for example, 2-t-butyl-6- (3-t-butyl-2-hydroxy-5-methylbenzyl) -4-methylphenyl acrylate, 2 , 4-di-t-amyl-6- (1- (3,5-di-t-amyl-2-hydroxyphenyl) ethyl) phenyl acrylate and the like, and JP-A Nos. 63-179953 and 1-168643. Acrylate compounds described in Japanese Patent Publication No. 1; octadecyl-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate, 2,2'-methylene-bis (4-methyl-6-tert-butylphenol) ), 1,1,3-tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, 1,3,5-trimethyl-2,4,6-tris (3 -Di-t-butyl-4-hydroxybenzyl) benzene, pentaerythritol-tetrakis (3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate), triethylene glycol bis (3- (3- alkyl-substituted phenolic compounds such as t-butyl-4-hydroxy-5-methylphenyl) propionate); 6- (4-hydroxy-3,5-di-t-butylanilino) -2,4-bisoctylthio-1 , 3,5-triazine, 4-bisoctylthio-1,3,5-triazine, 2-octylthio-4,6-bis- (3,5-di-t-butyl-4-oxyanilino) -1,3 , 5-triazine and other triazine group-containing phenol compounds;

  Further, the preferable phosphorus stabilizer is not particularly limited as long as it is a substance usually used in the general resin industry. For example, triphenyl phosphite, diphenylisodecyl phosphite, phenyl diisodecyl phosphite, tris (nonyl). Phenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite, 10- (3,5-di-t-butyl-4-hydroxybenzyl) -9 Monophosphite compounds such as 1,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide; 4,4′-butylidene-bis (3-methyl-6-tert-butylphenyl-di-tridecyl) Phosphite), 4,4'-isopropylidene-bis (phenyl-di-alkyl (C12-C15) phos Aito) diphosphite compounds such as and the like. Among these, monophosphite compounds are preferable, and tris (nonylphenyl) phosphite, tris (dinonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite and the like are particularly preferable.

  Preferred sulfur stabilizers include, for example, dilauryl 3,3-thiodipropionate, dimyristyl 3,3'-thiodipropionate, distearyl 3,3-thiodipropionate, lauryl stearyl 3,3- Thiodipropionate, pentaerythritol-tetrakis- (β-lauryl-thio-propionate), 3,9-bis (2-dodecylthioethyl) -2,4,8,10-tetraoxaspiro [5,5] undecane Etc.

  Although the compounding quantity of these stabilizers is suitably selected in the range which does not impair the objective of this invention, it is 0.01-2 mass parts normally with respect to 100 mass parts of resin, Preferably 0.01-1 mass part It is.

(Plasticizer)
When a norbornene resin is used as the resin, as a plasticizer, bis (2-ethylhexyl) adipate, bis (2-butoxyethyl) adipate, bis (2-ethylhexyl) azelate, dipropylene glycol dibenzoate, citric acid Tri-n-butyl, tri-n-butylacetyl citrate, epoxidized soybean oil, 2-ethylhexyl epoxidized tall oil, chlorinated paraffin, tri-2-ethylhexyl phosphate, tricresyl phosphate, tert-butyl phosphate Phenyl, tri-2-ethylhexyl diphenyl phosphate, dibutyl phthalate, diisohexyl phthalate, diheptyl phthalate, dinonyl phthalate, diundecyl phthalate, di-2-ethylhexyl phthalate, diisononyl phthalate, diisodecyl phthalate, ditridecyl phthalate Known butylbenzyl phthalate, dicyclohexyl phthalate, di-2-ethylhexyl sebacate, tri-2-ethylhexyl trimellitic acid, Santizer 278, Paraplex G40, Drapex 334F, Plastolein 9720, Mesamol, DNODP-610, HB-40, etc. Are applicable. The selection of the plasticizer and the addition amount are appropriately performed on the condition that the resin permeability and resistance to environmental changes are not impaired.

  In the present invention, other resins may be further blended with the above resin. Other resins are added within a range that does not impair the object of the present invention.

  Here, other resins that can be added to the resin are exemplified below.

  (1) A polymer derived from a hydrocarbon having one or two unsaturated bonds, specifically, for example, polyethylene, polypropylene, polymethylbut-1-ene, poly-4-methylpent-1-ene, polybuta Examples include polyolefins such as -1-ene and polystyrene. These polyolefins may have a crosslinked structure.

  (2) Halogen-containing vinyl polymer, specifically, polyvinyl chloride, polyvinylidene chloride, polyvinyl fluoride, polychloroprene, chlorinated rubber and the like.

  (3) A polymer derived from an α, β-unsaturated acid and its derivative, specifically, polyacrylate, polymethacrylate, polyacrylamide, polyacrylonitrile, or co-polymerization with the monomer constituting the polymer. Examples thereof include acrylonitrile / butadiene / styrene copolymer, acrylonitrile / styrene copolymer, and acrylonitrile / styrene / acrylic acid ester copolymer.

  (4) Polymers derived from unsaturated alcohols and amines, or acyl derivatives or acetals of unsaturated alcohols, specifically polyvinyl alcohol, polyvinyl acetate, vinyl stearate, polyvinyl benzoate, vinyl polymaleate. , Polyvinyl butyral, polyallyl phthalate, polyallyl melamine, or a copolymer with a monomer constituting the polymer, such as an ethylene / vinyl acetate copolymer.

  (5) A polymer derived from an epoxide, specifically, a polymer derived from polyethylene oxide or bisglycidyl ether.

  (6) Polyacetals, specifically, polyoxymethylene, polyoxyethylene, polyoxymethylene containing ethylene oxide as a comonomer, and the like.

  (7) Polyphenylene oxide (8) Polycarbonate (9) S Polysulfone (10) Polyurethane, urea resin and the like.

  (11) Polyamides and copolyamides derived from diamines and dicarboxylic acids and / or aminocarboxylic acids, or corresponding lactams, and specific examples include nylon 6, nylon 66, nylon 11, nylon 12, and the like.

  (12) Polyesters derived from dicarboxylic acids and dialcohols and / or oxycarboxylic acids, or corresponding lactones, such as polyethylene terephthalate, polybutylene terephthalate, poly 1,4-dimethylol / cyclohexane terephthalate. .

  (13) A polymer having a cross-linked structure derived from aldehyde and phenol, urea or melamine, and specifically includes phenol-formaldehyde resin, urea-formaldehyde resin, melamine-formaldehyde resin and the like.

  (14) Alkyd resin, specifically, glycerin / phthalic acid resin and the like.

  (15) Unsaturated polyester resins and halogen-containing modified resins derived from copolyesters of saturated and unsaturated dicarboxylic acids and polyhydric alcohols and obtained by using vinyl compounds as crosslinking agents.

  (16) Natural polymer, specifically, cellulose, rubber, protein, or derivatives thereof such as cellulose acetate, cellulose propionate, and cellulose ether.

  (17) Soft polymer, for example, a soft polymer containing a cyclic olefin component, an α-olefin copolymer, an α-olefin / diene copolymer, an aromatic vinyl hydrocarbon / conjugated diene soft copolymer And a soft polymer or copolymer comprising isobutylene or isobutylene / conjugated diene.

  (18) Hydrocarbon polymers having an alicyclic ring structure in the side chain are exemplified.

  As a method for mixing the resin binder with other resin components and additives, a method known per se can be applied. For example, a method of mixing each component simultaneously.

<Melt casting method>
There is no particular limitation on the method for forming the cycloolefin resin film, and either a heat-melt molding method or a solution casting method can be used. The heat-melt molding method can be further classified into an extrusion molding method, a press molding method, an inflation molding method, an injection molding method, a blow molding method, a stretch molding method, etc. Among these methods, mechanical strength, surface accuracy are included. In order to obtain an excellent film, an extrusion molding method, an inflation molding method, and a press molding method are preferable, and an extrusion molding method is most preferable. The molding conditions are appropriately selected depending on the purpose of use and the molding method. In the case of the hot melt molding method, the cylinder temperature is usually in the range of 150 to 400 ° C, preferably 200 to 350 ° C, more preferably 230 to 330 ° C. Is set as appropriate. If the resin temperature is too low, fluidity will deteriorate, causing shrinkage or distortion in the film. If the resin temperature is too high, voids or silver streaks will occur due to resin thermal decomposition, or the film will turn yellow. Defects may occur. The thickness of the film is usually in the range of 5 to 300 μm, preferably 10 to 200 μm, more preferably 20 to 100 μm. When the thickness is too thin, handling at the time of stacking becomes difficult, and when it is too thick, the drying time after stacking becomes long and productivity is lowered.

  The width of the film is preferably 1.4 m or more from the viewpoint of productivity and workability. More preferably, it is the range of 1.4-4m.

  The cycloolefin resin film has a surface wetting tension of preferably 40 mN / m or more, more preferably 50 mN / m or more, and still more preferably 55 mN / m or more. When the surface wetting tension is in the above range, the adhesive strength between the film and the polarizing film is improved. In order to adjust the surface wetting tension, for example, corona discharge treatment, plasma discharge treatment, ozone spraying, ultraviolet irradiation, flame treatment, chemical treatment, and other known surface treatments can be performed.

  The sheet before stretching needs to have a thickness of about 50 to 500 μm, and the thickness unevenness is preferably as small as possible. The entire surface is within ± 8%, preferably within ± 6%, more preferably within ± 4%. is there.

  In order to make the said cycloolefin resin film into the 2nd protective film of the polarizing plate which concerns on this invention, it obtains by extending | stretching a sheet | seat at least to a uniaxial direction. In addition, it may be substantially uniaxial stretching, for example, biaxial stretching in which uniaxial stretching is performed in order to orient the molecules after stretching in a range that does not affect the molecular orientation. Biaxial stretching is preferable, and it is preferable to use the tenter device or the like for stretching.

  The draw ratio is 1.1 to 10 times, preferably 1.3 to 8 times, and a desired retardation may be set within this range. If the draw ratio is too low, the absolute value of the retardation does not increase to a predetermined value, and if it is too high, it may break.

  Stretching is usually performed in a temperature range of Tg-20 ° C. to Tg + 30 ° C., preferably Tg to Tg + 30 ° C. of the resin constituting the sheet. If the stretching temperature is too low, it will break, and if it is too high, it will not be molecularly oriented, making it difficult to obtain the desired retardation.

  In the present invention, in order to accurately orient the polymer, it is also preferable to use a tenter that can independently control the web gripping length (distance from the start of gripping to the end of gripping) by the left and right gripping means of the tenter.

  Specifically, as a means for controlling the length of the portion gripping the left and right ends of the web by the tenter stretching apparatus independently on the left and right sides and making the grip length of the web different on the left and right, for example, [FIG. 3] There is something like [FIG. 3] schematically shows an example of a tenter stretching apparatus (15a) that is preferably used for producing the polymer film used in the present invention. In the same figure, the grip start position of the left and right grip means (clips) (12a) (12b) of the tenter stretching device (15a) is changed left and right, that is, the installation position of the clip closer (13a) (13b) is changed left and right. By changing the grip start position on the left and right, the left and right grip length of the film (F) is changed, thereby generating a force that twists the resin film (F) in the tenter (15a). Misalignment due to the conveyance can be corrected, and even if the conveyance distance from the peeling to the tenter is increased, the occurrence of meandering, slipping and wrinkling of the web can be effectively prevented. Reference numerals 14a and 14b denote clip openers.

  Although the illustrated tenter stretching device (15a) is schematically described, it is usually provided in a single row state of a pair of left and right rotational drive devices (ring-shaped chains) (11a) (11b) made of an endless chain. Of the large number of clips (12a) and (12b), the clips (12a) and (12b) of the straight forward transition portion of the chain that grips and pulls both left and right ends of the film (F) are in the width direction of the film (F). The tracks of the left and right chains (11a) and (11b) are installed so as to be gradually separated from each other, and the film (F) is stretched in the width direction.

  In the present invention, it is preferable to add a device for preventing meandering of a long film in order to correct wrinkles, strains, distortions, etc. with high accuracy, and an edge position controller (EPC) described in JP-A-6-8663. It is preferable to use a meandering correction device such as a center position controller (also referred to as CPC). These devices detect the edge of the film with an air servo sensor or optical sensor and control the transport direction based on that information so that the center of the edge of the film and the width direction is a constant transport position. Specifically, as the actuator, one or two guide rolls or a flat expander roll with drive is applied to the left and right (or up and down) with respect to the line direction to correct meandering, or to the left and right of the film A small pair of two pinch rolls is installed (one on the front and back of the film, and it is on both sides of the film), and the film is sandwiched and pulled to correct meandering. (Cross guider method). The principle of the meandering correction of these devices is that when the film is moving, for example, when going to the left, in the former method, the roll is tilted so that the film goes to the right, and in the latter method, one set on the right side is used. This pinch roll is nipped and pulled to the right. It is preferable to install at least one of these meandering prevention devices between the film peeling point and the tenter stretching device.

  In the film thus obtained, molecules can be oriented by stretching, and a retardation having a desired size can be obtained. In the second protective film of the present invention, preferable retardation values are Ro: 30 to 115 nm, Rt: 100 to 250 nm, Rt / Ro: 1.6 to 4.4, and more preferable Ro is 30. It is in the range of ˜70 nm.

  The retardation can be controlled by the retardation of the sheet before stretching, the stretching ratio, the stretching temperature, and the thickness of the stretched oriented film. When the sheet before stretching has a certain thickness, the larger the stretching ratio, the larger the absolute value of the retardation. Therefore, by changing the stretching ratio, it is possible to obtain a retardation film having a desired retardation. I can do it.

  Similarly, the wavelength dispersion characteristic D (R40) represented by Formula 1 of the laminate of the film and the retardation layer can be controlled in the range of 2.0 to 6.5 nm.

  The retardation Ro (in-plane) variation is preferably as small as possible, and the retardation film has a variation in Ro of a wavelength of 590 nm usually within ± 10 nm, preferably ± 5 nm or less, more preferably ± 1 nm or less.

  Variations in thickness and thickness unevenness within the retardation can be reduced by using these small unstretched sheets, and by applying stress evenly to the sheets during stretching. For this purpose, it is desirable to stretch in a controlled temperature environment under a uniform temperature distribution, preferably within ± 5 ° C., more preferably within ± 2 ° C., particularly preferably within ± 0.5 ° C.

<First, third, and fourth protective films>
The first, third, and fourth protective films of the present invention may use a cycloolefin resin film in the same manner as the second protective film. From the viewpoint of suitability for polarizing plate processing such as saponification treatment, cellulose ester It is preferable to use a system film. As the cellulose ester, cellulose acetate, cellulose acetate butyrate, cellulose acetate propionate, and cellulose acetate phthalate are preferable, and among these, cellulose acetate and cellulose acetate propionate are preferably used. As a commercially available cellulose ester film, for example, Konica Minoltack KC8UX, KC4UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC12UR, KC4FR, KC8UY-HA, HC8UX However, it is preferably used from the viewpoints of production, cost, transparency, adhesion and the like. These films may be films produced by melt casting film formation or films produced by solution casting film formation.

(Cellulose ester)
The cellulose ester used in the first, third, and fourth protective films of the present invention is an aliphatic carboxylic acid ester or aromatic carboxylic acid ester or aliphatic carboxylic acid ester having about 2 to 22 carbon atoms and an aromatic carboxylic acid. A mixed ester of esters is preferably used, and in particular, a lower fatty acid ester of cellulose is preferable. The lower fatty acid in the lower fatty acid ester of cellulose means a fatty acid having 6 or less carbon atoms. Specifically, it is described in cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate phthalate, etc., JP-A Nos. 10-45804, 8-231761, U.S. Pat. No. 2,319,052, and the like. And mixed fatty acid esters such as cellulose acetate propionate and cellulose acetate butyrate. Among the above descriptions, the lower fatty acid ester of cellulose preferably used for the third protective film is cellulose triacetate or the following cellulose acetate propionate.

  The cellulose ester has an acyl group having 2 to 22 carbon atoms as a substituent, a cellulose that simultaneously satisfies the following formulas 4 and 5 when the substitution degree of the acetyl group is X and the substitution degree of the propionyl group is Y: Ester.

Formula 4 2.00 ≦ X + Y ≦ 2.60
Formula 5 0.10 ≦ Y ≦ 1.00
Among them, 2.30 ≦ X + Y ≦ 2.55 is preferable, and 2.40 ≦ X + Y ≦ 2.55 is more preferable. Further, 0.50 ≦ Y ≦ 0.90 is preferable, and 0.70 ≦ Y ≦ 0.90 is more preferable.

  The portion not substituted with an acyl group usually exists as a hydroxyl group. These can be synthesized by known methods. Moreover, these acyl group substitution degrees can be measured according to the method prescribed | regulated to ASTM-D817-96.

  As the cellulose ester, a cellulose ester synthesized using cotton linter, wood pulp, kenaf or the like as a raw material can be used alone or in combination. In particular, it is preferable to use a cotton linter (hereinafter sometimes simply referred to as a linter) or a cellulose ester synthesized from wood pulp alone or in combination.

  Moreover, the cellulose ester obtained from these can be mixed and used in arbitrary ratios, respectively. These cellulose esters are prepared by using an organic acid such as acetic acid or an organic solvent such as methylene chloride when sulfuric acid is used as the acylating agent (acetic anhydride, propionic anhydride, butyric anhydride). It can obtain by making it react by a conventional method using a protic catalyst like.

  In the case of acetylcellulose, it is necessary to extend the time for the acetylation reaction in order to increase the acetylation rate. However, if the reaction time is too long, the decomposition proceeds at the same time, and the polymer chain is broken and the acetyl group is decomposed, resulting in undesirable results. Therefore, it is necessary to set the reaction time within a certain range in order to increase the degree of acetylation and suppress decomposition to some extent. It is not appropriate to define the reaction time because the reaction conditions are various and greatly change depending on the reaction apparatus, equipment and other conditions. As the decomposition of the polymer progresses, the molecular weight distribution becomes wider. Therefore, in the case of cellulose ester, the degree of decomposition can be defined by the value of weight average molecular weight (Mw) / number average molecular weight (Mn) that is usually used. That is, in the process of acetylation of cellulose triacetate, the weight average molecular weight is used as one index of the reaction degree for allowing the acetylation reaction to be carried out for a sufficient time for acetylation without being too long and being decomposed too much. The value of (Mw) / number average molecular weight (Mn) can be used.

  The ratio Mw / Mn of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the cellulose ester used in the present invention is preferably 1.4 to 3.0. In the present invention, the cellulose ester film may contain, as a material, a cellulose ester having a Mw / Mn value of 1.4 to 3.0, but the cellulose ester contained in the film (preferably cellulose triacetate). Or the value of Mw / Mn of cellulose acetate propionate) is more preferably in the range of 1.4 to 3.0. In the process of synthesizing cellulose ester, it is difficult to make it less than 1.4, and cellulose ester having a uniform molecular weight can be obtained by fractionation by gel filtration or the like. However, this method is very expensive. Moreover, it is preferable that it is 3.0 or less because the flatness is easily maintained. In addition, More preferably, it is 1.7-2.2.

  The molecular weight of the cellulose ester used in the present invention is preferably a number average molecular weight (Mn) of 80,000 to 200,000. More preferred are 100,000 to 200,000, particularly preferably 150,000 to 200,000.

  The average molecular weight and molecular weight distribution of the cellulose ester can be measured by a known method using high performance liquid chromatography. Using this, the number average molecular weight and the weight average molecular weight can be calculated, and the ratio (Mw / Mn) can be calculated.

  The measurement conditions are as follows. Solvent: Methylene chloride Column: Shodex K806, K805, K803G (used by connecting three Showa Denko Co., Ltd.) Column temperature: 25 ° C. Sample concentration: 0.1 mass% Detector: RI Model 504 (GL Science) Pump): L6000 (manufactured by Hitachi, Ltd.) Flow rate: 1.0 ml / min Calibration curve: Standard polystyrene STK standard Polystyrene (manufactured by Tosoh Corp.) Mw = 100000 to 500 calibration curves are used. did. It is preferable to obtain 13 samples at approximately equal intervals.

  The method for producing cellulose ester can be obtained by the method described in JP-A-10-45804.

  Cellulose esters are also affected by trace metal components in cellulose esters. These are considered to be related to water used in the production process, but it is preferable that there are few components that can become insoluble nuclei, and metal ions such as iron, calcium, and magnesium contain organic acidic groups. Insoluble matter may be formed by salt formation with a polymer degradation product or the like that may be present, and it is preferable that the amount is small. The iron (Fe) component is preferably 1 ppm or less. About calcium (Ca) component, it is contained in a lot of ground water and river water, etc., and it becomes hard water, and it is unsuitable as drinking water. Coordination compounds with ligands, that is, complexes are easily formed, and scum (insoluble starch, turbidity) derived from many insoluble calcium is formed.

  The calcium (Ca) component is 60 ppm or less, preferably 0 to 30 ppm. The magnesium (Mg) component is preferably in the range of 0 to 70 ppm, particularly preferably 0 to 20 ppm, since too much will cause insoluble matter. Metal components such as iron (Fe) content, calcium (Ca) content, magnesium (Mg) content, etc. are pre-processed by completely digesting cellulose ester with micro digest wet cracking equipment (sulfuric acid decomposition) and alkali melting. After performing, it can obtain | require by performing an analysis using ICP-AES (inductively coupled plasma optical emission spectrometry).

  The cellulose ester film used in the present invention preferably has a refractive index of 1.45 to 1.60 at 550 nm. As a method for measuring the refractive index of the film, an Abbe refractometer is used, and measurement is performed based on Japanese Industrial Standard JIS K 7105.

(Additive)
The cellulose ester film can contain additives such as a plasticizer, an ultraviolet absorber, an antioxidant, and a matting agent.

  In the above 2 and 3, the cellulose ester film used for the third protective film of the present invention preferably has a retardation in the range of 0 to 5 nm and Rt in the range of -10 to 10 nm. In order to obtain the above numerical range, if the third protective film is a cellulose ester film, it is produced by melt film formation, or by solution film formation, at a temperature of the glass transition point or more in the middle for 15 seconds or more. It is preferable to add an additive having a birefringence that is opposite to the birefringence of the cellulose ester. In that sense, the following acrylic polymer is preferably contained in order to adjust the retardation within the above range.

<Acrylic polymer>
The cellulose ester film used for the third protective film preferably contains an acrylic polymer having a weight average molecular weight of 500 or more and 30000 or less that exhibits negative orientation birefringence in the stretching direction. An acrylic polymer having a ring in the side chain or an acrylic polymer having a cyclohexyl group in the side chain is preferred.

  By controlling the composition of the polymer so that the weight average molecular weight of the polymer is 500 or more and 30000 or less, the compatibility between the cellulose ester and the polymer can be improved.

  In particular, for an acrylic polymer, an acrylic polymer having an aromatic ring in the side chain, or an acrylic polymer having a cyclohexyl group in the side chain, if the weight average molecular weight is preferably 500 or more and 10,000 or less, in addition to the above, The cellulose ester film has excellent transparency and extremely low moisture permeability, and exhibits excellent performance as a protective film for polarizing plates.

  Since the polymer has a weight average molecular weight of 500 or more and 30000 or less, it is considered to be between the oligomer and the low molecular weight polymer. In order to synthesize such a polymer, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can align the molecular weight as much as possible by a method that does not increase the molecular weight too much.

  Such polymerization methods include a method using a peroxide polymerization initiator such as cumene peroxide and t-butyl hydroperoxide, a method using a polymerization initiator in a larger amount than normal polymerization, and a mercapto compound in addition to the polymerization initiator. And a method of using a chain transfer agent such as carbon tetrachloride, a method of using a polymerization terminator such as benzoquinone and dinitrobenzene in addition to the polymerization initiator, and further, Japanese Patent Application Laid-Open No. 2000-128911 or 2000-344823. Examples thereof include a compound having one thiol group and a secondary hydroxyl group, or a bulk polymerization method using a polymerization catalyst in which the compound and an organometallic compound are used in combination. Although used, the method described in the publication is particularly preferable.

  Although the monomer as a monomer unit which comprises the polymer useful for this invention is mentioned below, it is not limited to this.

  The ethylenically unsaturated monomer unit constituting the polymer obtained by polymerizing the ethylenically unsaturated monomer is as a vinyl ester, for example, vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, caproic acid. Vinyl, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl benzoate, vinyl cinnamate Etc .; As acrylate ester, for example, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (n -, I-, s-), hexyl acrylate (n I-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), acrylic Cyclohexyl acid, acrylic acid (2-ethylhexyl), benzyl acrylate, phenethyl acrylate, acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3- Hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid-p-hydroxymethylphenyl, acrylic acid-p- (2-hydroxyethyl) phenyl, etc .; The above acrylic acid ester is changed to methacrylic acid ester; Examples thereof include acrylic acid, methacrylic acid, maleic anhydride, crotonic acid, itaconic acid and the like. The polymer composed of the above monomers may be a copolymer or a homopolymer, and is preferably a vinyl ester homopolymer, a vinyl ester copolymer, or a copolymer of vinyl ester and acrylic acid or methacrylic acid ester.

  In the present invention, an acrylic polymer (simply referred to as an acrylic polymer) refers to a homopolymer or copolymer of acrylic acid or methacrylic acid alkyl ester having no monomer unit having an aromatic ring or a cyclohexyl group. An acrylic polymer having an aromatic ring in the side chain is an acrylic polymer that always contains an acrylic acid or methacrylic acid ester monomer unit having an aromatic ring.

  The acrylic polymer having a cyclohexyl group in the side chain is an acrylic polymer containing an acrylic acid or methacrylic acid ester monomer unit having a cyclohexyl group.

  Examples of the acrylate monomer having no aromatic ring and cyclohexyl group include, for example, methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n-, i-) , Nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid 2-methoxy-ethyl), acrylic acid (2-ethoxyethyl), or the acrylic acid ester may include those obtained by changing the methacrylic ester.

  The acrylic polymer is a homopolymer or copolymer of the above-mentioned monomers, but the acrylic acid methyl ester monomer unit preferably has 30% by mass or more, and the methacrylic acid methyl ester monomer unit has 40% by mass or more. preferable. In particular, a homopolymer of methyl acrylate or methyl methacrylate is preferred.

  Examples of acrylic acid or methacrylic acid ester monomers having an aromatic ring include phenyl acrylate, phenyl methacrylate, acrylic acid (2 or 4-chlorophenyl), methacrylic acid (2 or 4-chlorophenyl), and acrylic acid (2 or 3 Or 4-ethoxycarbonylphenyl), methacrylic acid (2 or 3 or 4-ethoxycarbonylphenyl), acrylic acid (o or m or p-tolyl), methacrylic acid (o or m or p-tolyl), benzyl acrylate, Benzyl methacrylate, phenethyl acrylate, phenethyl methacrylate, acrylic acid (2-naphthyl) and the like can be mentioned, but benzyl acrylate, benzyl methacrylate, phenethyl acrylate, and phenethyl methacrylate are preferably used. That.

  Among acrylic polymers having an aromatic ring in the side chain, the acrylic acid or methacrylic acid ester monomer unit having an aromatic ring has 20 to 40% by mass, and the acrylic acid or methacrylic acid methyl ester monomer unit is 50 to 80% by mass. % Is preferable. The polymer preferably has 2 to 20% by mass of acrylic acid or methacrylic acid ester monomer units having a hydroxyl group.

  Examples of the acrylate monomer having a cyclohexyl group include cyclohexyl acrylate, cyclohexyl methacrylate, acrylic acid (4-methylcyclohexyl), methacrylic acid (4-methylcyclohexyl), acrylic acid (4-ethylcyclohexyl), and methacrylic acid. (4-ethylcyclohexyl) and the like can be mentioned, but cyclohexyl acrylate and cyclohexyl methacrylate can be preferably used.

  In the acrylic polymer having a cyclohexyl group in the side chain, the acrylic acid or methacrylic acid ester monomer unit having a cyclohexyl group has 20 to 40% by mass and preferably 50 to 80% by mass. Moreover, it is preferable to have 2-20 mass% of acrylic acid or methacrylic acid ester monomer units having a hydroxyl group in the polymer.

  A polymer obtained by polymerizing the above ethylenically unsaturated monomer, an acrylic polymer, an acrylic polymer having an aromatic ring in the side chain, and an acrylic polymer having a cyclohexyl group in the side chain are all excellent in compatibility with the cellulose resin.

  In the case of an acrylic acid or methacrylic acid ester monomer having these hydroxyl groups, it is not a homopolymer but a structural unit of a copolymer. In this case, it is preferable that the acrylic acid or methacrylic acid ester monomer unit having a hydroxyl group is contained in the acrylic polymer in an amount of 2 to 20% by mass.

  In the present invention, a polymer having a hydroxyl group in the side chain can also be preferably used. The monomer unit having a hydroxyl group is the same as the monomer described above, but acrylic acid or methacrylic acid ester is preferable. For example, acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3 -Hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), acrylic acid-p-hydroxymethylphenyl, acrylic acid-p- (2-hydroxyethyl) phenyl, or these acrylic acids. The thing replaced by methacrylic acid can be mentioned, Preferably, it is 2-hydroxyethyl acrylate and 2-hydroxyethyl methacrylate. The acrylic acid ester or methacrylic acid ester monomer unit having a hydroxyl group in the polymer is preferably contained in the polymer in an amount of 2 to 20% by mass, more preferably 2 to 10% by mass.

  A polymer containing 2 to 20% by mass of the above-mentioned monomer unit having a hydroxyl group, of course, is excellent in compatibility with cellulose ester, retention, dimensional stability, low moisture permeability, and polarized light. It is particularly excellent in adhesiveness with a polarizer as a plate protective film, and has the effect of improving the durability of the polarizing plate.

  The method of having a hydroxyl group at at least one terminal of the main chain of the acrylic polymer is not particularly limited as long as it has a hydroxyl group at the terminal of the main chain, but azobis (2-hydroxyethylbutyrate) A method using a radical polymerization initiator having such a hydroxyl group, a method using a chain transfer agent having a hydroxyl group such as 2-mercaptoethanol, a method using a polymerization terminator having a hydroxyl group, and terminating a hydroxyl group by living ion polymerization. A compound having one thiol group and a secondary hydroxyl group as disclosed in JP 2000-128911 A or 2000-344823, or a polymerization catalyst using the compound and an organometallic compound in combination The method described in the above publication is particularly preferred.

  The polymer produced by the method related to the description in this publication is commercially available as Act Flow Series manufactured by Soken Chemical Co., Ltd., and can be preferably used. In the present invention, the polymer having a hydroxyl group at the terminal and / or the polymer having a hydroxyl group in a side chain has an effect of significantly improving the compatibility and transparency of the polymer.

  Furthermore, a polymer using styrene as an ethylenically unsaturated monomer exhibiting negative orientation birefringence with respect to the stretching direction is preferred in order to develop negative refraction. Examples of styrenes include styrene, methyl styrene, dimethyl styrene, trimethyl styrene, ethyl styrene, isopropyl styrene, chloromethyl styrene, methoxy styrene, acetoxy styrene, chloro styrene, dichloro styrene, bromo styrene, and vinyl benzoic acid methyl ester. Although it is mentioned, it is not a thing limited to these.

  It may be copolymerized with the exemplified monomers listed as the unsaturated ethylenic monomer, or may be used by being dissolved in a cellulose ester using two or more kinds of the above polymers for the purpose of controlling birefringence.

  Further, the cellulose ester film used in the present invention is composed of an ethylenically unsaturated monomer Xa having no aromatic ring and a hydrophilic group in the molecule and an ethylenically unsaturated group having no hydrophilic ring and having a hydrophilic group in the molecule. A weight average molecular weight of 500 or more obtained by polymerizing a polymer X having a weight average molecular weight of 5000 or more and 30000 or less obtained by copolymerization with the monomer Xb, and more preferably an ethylenically unsaturated monomer Ya having no aromatic ring. It is preferable to contain 3000 or less polymer Y.

(Polymer X, Polymer Y)
The polymer X used in the present invention comprises an ethylenically unsaturated monomer Xa having no aromatic ring and a hydrophilic group in the molecule and an ethylenically unsaturated monomer Xb having no aromatic ring and having a hydrophilic group in the molecule. It is a polymer having a weight average molecular weight of 5,000 to 30,000 obtained by copolymerization. Preferably, Xa is an acrylic or methacrylic monomer that does not have an aromatic ring and a hydrophilic group in the molecule, and Xb is an acrylic or methacrylic monomer that does not have an aromatic ring in the molecule and has a hydrophilic group.

  The polymer X used in the present invention is represented by the following general formula (X).

Formula (X)
-(Xa) m- (Xb) n- (Xc) p-
More preferably, it is a polymer represented by the following general formula (X-1).

Formula (X-1)
_{- [CH 2 -C (-R1)} (- CO 2 R2)] m- [CH 2 -C (-R3) (- CO 2 R4-OH) -] n- [Xc] p-
(In the formula, R 1 and R ₃ represent H or CH _3. R ₂ represents an alkyl group having 1 to 12 carbon atoms or a cycloalkyl group. R ₄ represents —CH ₂ —, —C ₂ H ₄ — or —C _3. Represents H _6- , Xc represents a monomer unit polymerizable to Xa and Xb, m, n and p represent molar composition ratios, provided that m ≠ 0, n ≠ 0, k ≠ 0, m + n + p = 100 .)
Although the monomer as a monomer unit which comprises the polymer X used for this invention is mentioned below, it is not limited to this.

  In X, the hydrophilic group means a group having a hydroxyl group or an ethylene oxide chain.

  Examples of the ethylenically unsaturated monomer Xa having no aromatic ring and no hydrophilic group in the molecule include methyl acrylate, ethyl acrylate, propyl acrylate (i-, n-), and butyl acrylate (n-, i- , S-, t-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (n-, i-), octyl acrylate (n- I-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), acrylic acid (2-ethylhexyl), acrylic acid (ε-caprolactone), acrylic acid (2-ethoxyethyl) ) Or the like, or those obtained by replacing the acrylic ester with a methacrylic ester. Among these, methyl acrylate, ethyl acrylate, methyl methacrylate, ethyl methacrylate, and propyl methacrylate (i-, n-) are preferable.

  The ethylenically unsaturated monomer Xb having no aromatic ring in the molecule and having a hydrophilic group is preferably acrylic acid or methacrylic acid ester as a monomer unit having a hydroxyl group. For example, acrylic acid (2-hydroxyethyl), List acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropyl), acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), or those in which these acrylic acids are replaced by methacrylic acid. Acrylic acid (2-hydroxyethyl) and methacrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), and acrylic acid (3-hydroxypropyl) are preferable.

  Xc is not particularly limited as long as it is an ethylenically unsaturated monomer other than Xa and Xb and copolymerizable, but preferably has no aromatic ring.

  The molar composition ratio m: n of Xa, Xb and Xc is preferably in the range of 99: 1 to 65:35, more preferably in the range of 95: 5 to 75:25. P of Xc is 0-10. Xc may be a plurality of monomer units.

  When the molar composition ratio of Xa is large, the compatibility with the cellulose ester is improved, but the retardation value Rt in the film thickness direction is increased. When the molar composition ratio of Xb is large, the compatibility is deteriorated, but the effect of reducing Rt is high. Further, if the molar composition ratio of Xb exceeds the above range, haze tends to occur during film formation, and it is preferable to optimize these and determine the molar composition ratio of Xa and Xb.

  As for the molecular weight of the polymer X, the weight average molecular weight is from 5,000 to 30,000, more preferably from 8,000 to 25,000.

  By setting the weight average molecular weight to 5,000 or more, it is preferable because the cellulose ester film has advantages such as less dimensional change under high temperature and high humidity and less curling as a polarizing plate protective film. When the weight average molecular weight is 30000 or less, the compatibility with the cellulose ester is further improved, and bleeding out under high temperature and high humidity, and further haze generation immediately after film formation is suppressed.

  The weight average molecular weight of the polymer X used in the present invention can be adjusted by a known molecular weight adjusting method. Examples of such a molecular weight adjusting method include a method of adding a chain transfer agent such as carbon tetrachloride, lauryl mercaptan, octyl thioglycolate, and the like. The polymerization temperature is usually room temperature to 130 ° C., preferably 50 ° C. to 100 ° C., and this temperature or the polymerization reaction time can be adjusted.

  The measuring method of a weight average molecular weight can be based on the following method.

(Weight average molecular weight measurement method)
The weight average molecular weight Mw was measured using gel permeation chromatography.

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000-500 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.

  The polymer Y used in the present invention is a polymer having a weight average molecular weight of 500 or more and 3000 or less obtained by polymerizing an ethylenically unsaturated monomer Ya having no aromatic ring.

  A weight average molecular weight of 500 or more is preferable because the residual monomer of the polymer is reduced. Moreover, it is preferable to set it as 3000 or less in order to maintain retardation value Rt fall performance.

  Ya is preferably an acrylic or methacrylic monomer having no aromatic ring.

  The polymer Y used in the present invention is represented by the following general formula (Y).

General formula (Y)
-(Ya) k- (Yb) q-
More preferably, it is a polymer represented by the following general formula (Y-1).

General formula (Y-1)
_{- [CH 2 -C (-R5)} (- CO 2 R6)] k- [Yb] q- ( wherein, R5 is, .R6 representing H or CH ₃ is an alkyl group having 1 to 12 carbon atoms cycloalkyl Represents an alkyl group, Yb represents a monomer unit copolymerizable with Ya, and k and q represent a molar composition ratio, provided that k ≠ 0 and k + q = 100.
Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya. Yb may be plural. k + q = 100, q is preferably 0-30.

  The ethylenically unsaturated monomer Ya constituting the polymer Y obtained by polymerizing an ethylenically unsaturated monomer having no aromatic ring is, for example, methyl acrylate, ethyl acrylate, propyl acrylate (i- , N-), butyl acrylate (n-, i-, s-, t-), pentyl acrylate (n-, i-, s-), hexyl acrylate (n-, i-), heptyl acrylate (N-, i-), octyl acrylate (n-, i-), nonyl acrylate (n-, i-), myristyl acrylate (n-, i-), cyclohexyl acrylate, acrylic acid (2- Ethyl hexyl), acrylic acid (ε-caprolactone), acrylic acid (2-hydroxyethyl), acrylic acid (2-hydroxypropyl), acrylic acid (3-hydroxypropiyl) ), Acrylic acid (4-hydroxybutyl), acrylic acid (2-hydroxybutyl), methacrylic acid ester, the above acrylic acid ester changed to methacrylic acid ester; unsaturated acid, for example, acrylic acid, methacrylic acid And maleic anhydride, crotonic acid, itaconic acid and the like.

  Yb is not particularly limited as long as it is an ethylenically unsaturated monomer copolymerizable with Ya. Examples of vinyl esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl valerate, vinyl pivalate, and vinyl caproate. Vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl cyclohexanecarboxylate, vinyl octylate, vinyl methacrylate, vinyl crotonate, vinyl sorbate, vinyl cinnamate and the like are preferred. Yb may be plural.

  In order to synthesize the polymers X and Y, it is difficult to control the molecular weight in normal polymerization, and it is desirable to use a method that can make the molecular weights as uniform as possible without increasing the molecular weight. Such polymerization methods include a method using a peroxide polymerization initiator such as cumene peroxide and t-butyl hydroperoxide, a method using a polymerization initiator in a larger amount than normal polymerization, and a mercapto compound in addition to the polymerization initiator. And a method of using a chain transfer agent such as carbon tetrachloride, a method of using a polymerization terminator such as benzoquinone and dinitrobenzene in addition to the polymerization initiator, and further, Japanese Patent Application Laid-Open No. 2000-128911 or 2000-344823. Examples thereof include a compound having one thiol group and a secondary hydroxyl group, or a bulk polymerization method using a polymerization catalyst in which the compound and an organometallic compound are used in combination. In particular, a polymerization method using a compound having a thiol group and a secondary hydroxyl group in the molecule as a chain transfer agent. It is preferred.

  In this case, the terminal of the polymer X and the polymer Y has a hydroxyl group and a thioether resulting from the polymerization catalyst and the chain transfer agent. By this terminal residue, the compatibility between the polymers X and Y and the cellulose ester can be adjusted.

  The hydroxyl values of the polymers X and Y are preferably 30 to 150 [mg KOH / g].

(Measurement method of hydroxyl value)
This measurement conforms to JIS K 0070 (1992). This hydroxyl value is defined as the number of mg of potassium hydroxide required to neutralize acetic acid bonded to a hydroxyl group when 1 g of a sample is acetylated. Specifically, sample Xg (about 1 g) is precisely weighed in a flask, and 20 ml of an acetylating reagent (a solution obtained by adding pyridine to 20 ml of acetic anhydride to 400 ml) is accurately added thereto. An air cooling tube is attached to the mouth of the flask and heated in a glycerin bath at 95-100 ° C.

  After 1 hour and 30 minutes, the mixture is cooled, 1 ml of purified water is added from an air condenser, and acetic anhydride is decomposed into acetic acid. Next, titration is performed with a 0.5 mol / L potassium hydroxide ethanol solution using a potentiometric titrator, and the inflection point of the obtained titration curve is set as the end point. Further, as a blank test, titration is performed without a sample, and an inflection point of the titration curve is obtained.

  The hydroxyl value is calculated by the following formula.

Hydroxyl value = {(BC) × f × 28.05 / X} + D (wherein B is the amount (ml) of 0.5 mol / L potassium hydroxide ethanol solution used in the blank test, and C is titration. The amount of 0.5 mol / L potassium hydroxide ethanol solution used in (ml), f is a factor of 0.5 mol / L potassium hydroxide ethanol solution, D is the acid value, and 28.05 is potassium hydroxide. (It represents 1/2 of 1mol amount 56.11)
The above-mentioned polymer X and polymer Y are both excellent in compatibility with cellulose ester, excellent in productivity without evaporation and volatilization, good retention as a protective film for polarizing plates, low moisture permeability, and dimensional stability. Are better.

The content of the polymer X and the polymer Y in the cellulose ester film is preferably in a range satisfying the following formulas (i) and (ii). When the content of the polymer X is Xg (mass% = the mass of the polymer X / the mass of the cellulose ester × 100) and the content of the polymer Y is Yg (mass%),
Formula (i) 5 ≦ Xg + Yg ≦ 35 (mass%)
Formula (ii) 0.05 ≦ Yg / (Xg + Yg) ≦ 0.4
A preferable range of the formula (i) is 10 to 25% by mass.

  If the total amount of the polymer X and the polymer Y is 5% by mass or more, the polymer X and the polymer Y sufficiently act to reduce the retardation value Rt. Moreover, if it is 35 mass% or less as a total amount, adhesiveness with polarizer PVA is favorable.

  The polymer X and the polymer Y can be directly added and dissolved as a material constituting the dope liquid described later, or can be added to the dope liquid after being previously dissolved in an organic solvent for dissolving the cellulose ester.

(Other additives)
The cellulose ester film that is the first, third, and fourth protective films can contain an additive that can be added to a normal cellulose ester film.

  Examples of these additives include plasticizers, ultraviolet absorbers, and fine particles.

  The present invention preferably contains the following plasticizer. Examples of plasticizers include phosphate ester plasticizers, phthalate ester plasticizers, trimellitic acid ester plasticizers, pyromellitic acid plasticizers, glycolate plasticizers, citrate ester plasticizers, and polyesters. A plasticizer, a polyhydric alcohol ester plasticizer, and the like can be preferably used.

  For phosphate plasticizers, triphenyl phosphate, tricresyl phosphate, cresyl diphenyl phosphate, octyl diphenyl phosphate, diphenylbiphenyl phosphate, trioctyl phosphate, tributyl phosphate, etc. For phthalate ester plasticizers, diethyl phthalate, dimethoxy For trimellitic acid plasticizers such as ethyl phthalate, dimethyl phthalate, dioctyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, butyl benzyl phthalate, diphenyl phthalate, dicyclohexyl phthalate, tributyl trimellitate, triphenyl trimellitate, triethyl For pyromellitic acid ester plasticizers such as trimellitate, tetrabutylpyromellitate, In the case of glycolate plasticizers such as lupyromelitate and tetraethylpyromellitate, triacetin, tributyrin, ethylphthalylethyl glycolate, methylphthalylethyl glycolate, butylphthalylbutyl glycolate, etc. Citrate, tri-n-butyl citrate, acetyl triethyl citrate, acetyl tri-n-butyl citrate, acetyl tri-n- (2-ethylhexyl) citrate and the like can be preferably used. Examples of other carboxylic acid esters include butyl oleate, methylacetyl ricinoleate, dibutyl sebacate, and various trimellitic acid esters.

  As the polyester plasticizer, a copolymer of a dibasic acid and a glycol such as an aliphatic dibasic acid, an alicyclic dibasic acid, or an aromatic dibasic acid can be used. The aliphatic dibasic acid is not particularly limited, and adipic acid, sebacic acid, phthalic acid, terephthalic acid, 1,4-cyclohexyl dicarboxylic acid, and the like can be used. As glycol, ethylene glycol, diethylene glycol, 1,3-propylene glycol, 1,2-propylene glycol, 1,4-butylene glycol, 1,3-butylene glycol, 1,2-butylene glycol and the like can be used. These dibasic acids and glycols may be used alone or in combination of two or more.

  The polyhydric alcohol ester plasticizer comprises an ester of a divalent or higher aliphatic polyhydric alcohol and a monocarboxylic acid. Examples of preferred polyhydric alcohols include the following, but the present invention is not limited to these. Adonitol, arabitol, ethylene glycol, diethylene glycol, triethylene glycol, tetraethylene glycol, 1,2-propanediol, 1,3-propanediol, dipropylene glycol, tripropylene glycol, 1,2-butanediol, 1,3-butanediol 1,4-butanediol, dibutylene glycol, 1,2,4-butanetriol, 1,5-pentanediol, 1,6-hexanediol, hexanetriol, 2-n-butyl-2-ethyl-1,3- Propanediol, galactitol, mannitol, 3-methylpentane-1,3,5-triol, pinacol, sorbitol, trimethylolpropane, trimethylolethane, xylitol, and the like can be raised. In particular, triethylene glycol, tetraethylene glycol, dipropylene glycol, tripropylene glycol, sorbitol, trimethylolpropane, and xylitol are preferable. There is no restriction | limiting in particular as monocarboxylic acid used for polyhydric alcohol ester, Well-known aliphatic monocarboxylic acid, alicyclic monocarboxylic acid, aromatic monocarboxylic acid, etc. can be used. Use of an alicyclic monocarboxylic acid or aromatic monocarboxylic acid is preferred in terms of improving moisture permeability and retention. Examples of preferred monocarboxylic acids include the following, but the present invention is not limited thereto. As the aliphatic monocarboxylic acid, a fatty acid having a straight chain or a side chain having 1 to 32 carbon atoms can be preferably used. It is more preferable that it is C1-C20, and it is especially preferable that it is C1-C10. When acetic acid is contained, the compatibility with the cellulose ester is increased, and it is also preferable to use a mixture of acetic acid and another monocarboxylic acid. Preferred aliphatic monocarboxylic acids include acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, enanthic acid, caprylic acid, pelargonic acid, capric acid, 2-ethyl-hexanecarboxylic acid, undecylic acid, lauric acid, tridecylic acid, Saturated fatty acids such as myristic acid, pentadecylic acid, palmitic acid, heptadecylic acid, stearic acid, nonadecanoic acid, arachidic acid, behenic acid, lignoceric acid, serotic acid, heptacosanoic acid, montanic acid, melicic acid, and laccelic acid, undecylenic acid, olein Unsaturated fatty acids such as acid, sorbic acid, linoleic acid, linolenic acid and arachidonic acid can be raised. Examples of preferable alicyclic monocarboxylic acid include cyclopentanecarboxylic acid, cyclohexanecarboxylic acid, cyclooctanecarboxylic acid, and derivatives thereof. Examples of preferred aromatic monocarboxylic acids include those in which an alkyl group is introduced into the benzene ring of benzoic acid such as benzoic acid and toluic acid, and two or more benzene rings such as biphenyl carboxylic acid, naphthalene carboxylic acid, and tetralin carboxylic acid. Aromatic monocarboxylic acids or derivatives thereof can be raised. Particularly preferred is benzoic acid. The molecular weight of the polyhydric alcohol ester is not particularly limited, but is preferably in the range of 300 to 1500, and more preferably in the range of 350 to 750. The larger one is preferable in terms of improving the retention, and the smaller one is preferable in terms of moisture permeability and compatibility with the cellulose ester.

  The carboxylic acid used for the polyhydric alcohol ester may be one kind or a mixture of two or more kinds. Moreover, all the OH groups in the polyhydric alcohol may be esterified with carboxylic acid, or a part of the OH groups may be left as they are.

  These plasticizers are preferably used alone or in combination.

  The amount of these plasticizers used is preferably from 1 to 20% by mass, particularly preferably from 3 to 13% by mass, based on the cellulose ester, in terms of film performance, processability and the like.

  The ultraviolet absorber that can be used in the present invention aims to improve durability by absorbing ultraviolet rays of 400 nm or less, and preferably has a transmittance of 10% or less at a wavelength of 370 nm. More preferably, it is 5% or less, and further preferably 2% or less.

  Although the ultraviolet absorber used in the present invention is not particularly limited, for example, oxybenzophenone compounds, benzotriazole compounds, salicylic acid ester compounds, benzophenone compounds, cyanoacrylate compounds, triazine compounds, nickel complex compounds, inorganic powders Examples include the body. It is good also as a polymer type ultraviolet absorber.

  It is preferable to use fine particles for the cellulose ester film used in the present invention. As the fine particles, both inorganic compounds and organic compounds can be used. Examples of inorganic compounds include silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium silicate, hydrated calcium silicate, aluminum silicate, magnesium silicate And calcium phosphate. Fine particles containing silicon are preferable in terms of low turbidity, and silicon dioxide is particularly preferable.

  The average primary particle size of the fine particles is preferably 5 to 50 nm, and more preferably 7 to 20 nm. These are preferably contained mainly as secondary aggregates having a particle size of 0.05 to 0.3 μm. The content of these fine particles in the cellulose ester film is preferably 0.05 to 1% by mass, particularly preferably 0.1 to 0.5% by mass. In the case of a cellulose ester film having a multilayer structure by the co-casting method, it is preferable to contain fine particles of this addition amount on the surface.

  Silicon dioxide fine particles are commercially available, for example, under the trade names Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600 (manufactured by Nippon Aerosil Co., Ltd.). it can.

  Zirconium oxide fine particles are commercially available, for example, under the trade names Aerosil R976 and R811 (manufactured by Nippon Aerosil Co., Ltd.) and can be used.

  Examples of the polymer include silicone resin, fluororesin, and acrylic resin. Silicone resins are preferable, and those having a three-dimensional network structure are particularly preferable. For example, Tospearl 103, 105, 108, 120, 145, 3120, and 240 (manufactured by Toshiba Silicone Co., Ltd.) It is marketed by name and can be used.

  Among these, Aerosil 200V and Aerosil R972V are particularly preferably used because they have a large effect of reducing the friction coefficient while keeping the turbidity of the cellulose ester film low.

(Method for producing cellulose ester film)
Next, the manufacturing method of the cellulose ester film used for this invention is demonstrated.

  The cellulose ester film used in the present invention is preferably a cellulose ester film produced by a solution casting method or melt casting. Hereinafter, the solution casting method will be described.

  The cellulose ester film used in the present invention was produced by dissolving a cellulose ester and an additive in a solvent to prepare a dope, casting a dope onto an endless metal support, and casting the dope. The step of drying the dope as a web, the step of peeling from the metal support, the step of stretching or maintaining the width, the step of further drying, and the step of winding up the finished film are performed.

  The process for preparing the dope will be described. The concentration of cellulose ester in the dope is preferably higher because the drying load after casting on the metal support can be reduced. However, if the concentration of cellulose ester is too high, the load during filtration increases and the filtration accuracy is poor. Become. As a density | concentration which makes these compatible, 10-35 mass% is preferable, More preferably, it is 15-25 mass%.

  The solvent used in the dope may be used alone or in combination of two or more, but it is preferable to use a mixture of a good solvent and a poor solvent of cellulose ester in terms of production efficiency, and there are many good solvents. This is preferable from the viewpoint of the solubility of the cellulose ester.

  The preferable range of the mixing ratio of the good solvent and the poor solvent is 70 to 98% by mass for the good solvent and 2 to 30% by mass for the poor solvent. With a good solvent and a poor solvent, what dissolve | melts the cellulose ester to be used independently is defined as a good solvent, and what poorly swells or does not melt | dissolve is defined as a poor solvent.

  Therefore, depending on the average acetylation degree (acetyl group substitution degree) of the cellulose ester, the good solvent and the poor solvent change. For example, when acetone is used as the solvent, the cellulose ester acetate (acetyl group substitution degree 2.4), cellulose Acetate propionate is a good solvent, and cellulose acetate (acetyl group substitution degree 2.8) is a poor solvent.

  Although the good solvent used for this invention is not specifically limited, Organic halogen compounds, such as a methylene chloride, dioxolanes, acetone, methyl acetate, methyl acetoacetate, etc. are mentioned. Particularly preferred is methylene chloride or methyl acetate.

  Moreover, although the poor solvent used for this invention is not specifically limited, For example, methanol, ethanol, n-butanol, cyclohexane, cyclohexanone, etc. are used preferably. Moreover, it is preferable that 0.01-2 mass% of water contains in dope. Moreover, the solvent used for melt | dissolution of a cellulose ester collect | recovers the solvent removed from the film by drying at the film-forming process, and uses this again.

  A general method can be used as a dissolution method of the cellulose ester when preparing the dope described above. When heating and pressurization are combined, it is possible to heat above the boiling point at normal pressure. It is preferable to stir and dissolve while heating at a temperature that is equal to or higher than the boiling point of the solvent at normal pressure and does not boil under pressure, in order to prevent the formation of massive undissolved materials called gels and mamacos. Moreover, after mixing a cellulose ester with a poor solvent and making it wet or swell, the method of adding a good solvent and melt | dissolving is also used preferably.

  The pressurization may be performed by a method of injecting an inert gas such as nitrogen gas or a method of increasing the vapor pressure of the solvent by heating. Heating is preferably performed from the outside. For example, a jacket type is preferable because temperature control is easy.

  The heating temperature with the addition of a solvent is preferably higher from the viewpoint of the solubility of the cellulose ester, but if the heating temperature is too high, the required pressure increases and the productivity deteriorates. A preferable heating temperature is 45 to 120 ° C, more preferably 60 to 110 ° C, and still more preferably 70 ° C to 105 ° C. The pressure is adjusted so that the solvent does not boil at the set temperature.

  Alternatively, a cooling dissolution method is also preferably used, whereby the cellulose ester can be dissolved in a solvent such as methyl acetate.

  Next, this cellulose ester solution is filtered using a suitable filter medium such as filter paper. As the filter medium, it is preferable that the absolute filtration accuracy is small in order to remove insoluble matters and the like, but there is a problem that the filter medium is likely to be clogged if the absolute filtration accuracy is too small. For this reason, a filter medium with an absolute filtration accuracy of 0.008 mm or less is preferable, a filter medium with 0.001 to 0.008 mm is more preferable, and a filter medium with 0.003 to 0.006 mm is still more preferable.

  There are no particular restrictions on the material of the filter medium, and ordinary filter media can be used. However, plastic filter media such as polypropylene and Teflon (registered trademark), and metal filter media such as stainless steel do not drop off fibers. preferable. It is preferable to remove and reduce impurities, particularly bright spot foreign matter, contained in the raw material cellulose ester by filtration.

The bright spot foreign matter was placed in a crossed Nicols state with two polarizing plates, a rolled cellulose ester was placed between them, and light was applied from the side of one polarizing plate, and observed from the side of the other polarizing plate. It is a point (foreign matter) that light from the opposite side appears to leak sometimes, and the number of bright spots having a diameter of 0.01 mm or more is preferably 200 / cm ² or less. More preferably, it is 100 pieces / cm < ² > or less, More preferably, it is 50 pieces / m < ² > or less, More preferably, it is 0-10 pieces / cm < ² > or less. Further, it is preferable that the number of bright spots of 0.01 mm or less is small.

  The dope can be filtered by a normal method, but the method of filtering while heating at a temperature not lower than the boiling point of the solvent at normal pressure and in a range where the solvent does not boil under pressure is the filtration pressure before and after filtration. The increase in the difference (referred to as differential pressure) is small and preferable. A preferred temperature is 45 to 120 ° C, more preferably 45 to 70 ° C, and still more preferably 45 to 55 ° C.

  A smaller filtration pressure is preferred. The filtration pressure is preferably 1.6 MPa or less, more preferably 1.2 MPa or less, and further preferably 1.0 MPa or less.

  Here, the dope casting will be described.

  The metal support in the casting (casting) step preferably has a mirror-finished surface. As the metal support, a stainless steel belt or a drum whose surface is plated with a casting is preferably used. The cast width can be 1 to 4 m. The surface temperature of the metal support in the casting step is −50 ° C. to a temperature lower than the boiling point of the solvent, and a higher temperature is preferable because the web can be dried faster. May deteriorate. A preferable support body temperature is 0-40 degreeC, and 5-30 degreeC is still more preferable.

  Alternatively, it is also a preferable method that the web is gelled by cooling and peeled from the drum in a state containing a large amount of residual solvent.

  The method for controlling the temperature of the metal support is not particularly limited, and there are a method of blowing hot air or cold air, and a method of contacting hot water with the back side of the metal support. It is preferable to use warm water because heat transfer is performed efficiently, so that the time until the temperature of the metal support becomes constant is short. When warm air is used, wind at a temperature higher than the target temperature may be used.

  In order for the cellulose ester film to exhibit good flatness, the residual solvent amount when peeling the web from the metal support is preferably 10 to 150% by mass, more preferably 20 to 40% by mass or 60 to 130% by mass. Especially preferably, it is 20-30 mass% or 70-120 mass%.

  Further, in the drying step of the cellulose ester film, the web is peeled off from the metal support, and further dried, and the residual solvent amount is preferably 1% by mass or less, more preferably 0.1% by mass or less, Especially preferably, it is 0-0.01 mass% or less.

  In the film drying process, generally, a roll drying method (a method in which a plurality of rolls arranged on the upper and lower sides are alternately passed through and dried) or a method of drying while transporting the web by a tenter method is adopted.

  In order to produce the cellulose ester film used for the third protective film according to the present invention, the web is stretched in the transport direction (= long direction) where the residual solvent amount of the web immediately after peeling from the metal support is large. The web is preferably stretched in the width direction by a tenter method in which both ends of the web are gripped by clips or the like.

  The stretching operation may be performed in multiple stages, and biaxial stretching is preferably performed in the casting direction and the width direction. Also, when biaxial stretching is performed, simultaneous biaxial stretching may be performed or may be performed stepwise. In this case, stepwise means that, for example, stretching in different stretching directions can be sequentially performed, stretching in the same direction is divided into multiple stages, and stretching in different directions is added to any one of the stages. Is also possible.

  A preferable draw ratio is 1.05 to 2 times, preferably 1.1 to 1.5 times. In the case of simultaneous biaxial stretching, the film may be contracted in the longitudinal direction, or may be contracted so as to be 0.8 to 0.99, preferably 0.9 to 0.99. Preferably, the area is preferably 1.12 times to 1.44 times, more preferably 1.15 times to 1.32 times, due to transverse stretching and longitudinal stretching or shrinkage. This can be determined by the draw ratio in the longitudinal direction × the draw ratio in the transverse direction.

  In addition, the “stretch direction” in the present invention is usually used to mean a direction in which a stretching stress is directly applied when performing a stretching operation. In some cases, it is used in the sense of the one having a higher draw ratio (that is, the direction usually serving as the slow axis).

  The retardation of the first protective film and the fourth protective film used in the polarizing plate of the present invention is not particularly limited, and the retardation Ro in the in-plane direction is preferably in the range of 30 nm to 1000 nm. More preferably, it is in the range of 30 nm to 500 nm, particularly preferably in the range of 30 nm to 150 nm, and most preferably in the range of 30 nm to 75 nm. Moreover, as retardation Rt of the thickness direction, the range of 30 nm-1000 nm is preferable, More preferably, it is the range of 30 nm-500 nm, Most preferably, it is the range of 30 nm-250 nm.

  The cellulose ester film used for the first, third and fourth protective films according to the present invention preferably has a thickness in the range of 20 to 200 μm, more preferably 20 to 100 μm, and more preferably 20 to 200 μm. More preferably, it is 80 μm. The cellulose ester film used for the third protective film is particularly preferably 20 to 45 μm in thickness, in addition to the effect of widening the viewing angle, in order to stably suppress changes in color.

"Polarizer"
The polarizing plate can be produced by a general method. It is preferable that the back side of the cycloolefin resin film as the second protective film of the present invention is bonded to at least one surface of a polarizing film produced by immersing and stretching in an iodine solution via a primer solution. As the primer solution, a solution obtained by dissolving a hydrogenated product of maleic anhydride-modified styrene / butadiene / styrene block copolymer in a solvent can be preferably used.

  In the case where a cellulose ester film is used for the first, third, and fourth protective films of the present invention, at least a polarizing film prepared by subjecting the back side of the film to alkali saponification treatment and immersion drawing in an iodine solution. It is preferable to attach to one surface using a completely saponified polyvinyl alcohol aqueous solution. It is also preferable to use a commercially available polarizing plate protective film. For example, Konica Minoltak KC8UX, KC4UX, KC5UX, KC8UCR3, KC8UCR4, KC8UCR5, KC8UY, KC4UY, KC12UR, KC4FR, etc. .

  A polarizing film, which is a main component of a polarizing plate, is an element that transmits only light having a plane of polarization in a certain direction. A typical polarizing film currently known is a polyvinyl alcohol polarizing film, which is a polyvinyl alcohol film. There are one in which iodine is dyed on a system film and one in which dichroic dye is dyed. As the polarizing film, a polyvinyl alcohol aqueous solution is formed and dyed by uniaxially stretching or dyed, or uniaxially stretched after dyeing, and then preferably subjected to a durability treatment with a boron compound.

<Display device>
By incorporating the polarizing plate of the present invention into a liquid crystal display device, the liquid crystal display device of the present invention having excellent visibility can be produced. The polarizing plate of the present invention is preferably used in an IPS mode type LCD, but is particularly preferably used in an IPS mode type liquid crystal display device adopting the configuration of 2 or 3. In particular, even a large-screen liquid crystal display device with a screen of 30 or more types, particularly 30 to 54 types, has a high contrast, and in particular, has the effect of suppressing color change due to viewing angle and preventing eye fatigue even during long-time viewing. .

  EXAMPLES The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

Example 1
<< Measurement of retardation and chromatic dispersion >>
In the examples, retardation measurement was performed in an environment of 23 ° C., 55% RH, wavelength 590 nm using KOBRA 21ADH manufactured by Oji Scientific Instruments. Further, when calculating the retardation in the thickness direction, a value obtained by measuring the refractive index of each layer using an Abbe refractometer was used. In the case of a laminate, the average value of the refractive index of each layer was used. Calculation of retardation and wavelength dispersion characteristic D (R40) used the following formula 1, formula 2, and formula 3.

Formula 1: D (R40) = R40 (630) −R40 (480) (wherein R40 represents a retardation value measured by tilting the slow axis in the plane of the sample by 40 ° about the rotation axis (630). (480) represents each measurement wavelength (nm).)
Formula 2: Ro = (nx−ny) × d
Formula 3: Rt = ((nx + ny) / 2−nz) × d (wherein the in-plane slow phase of the second protective film or the retardation layer or the laminate of the second protective film and the retardation layer) (The refractive index in the axial direction is nx, the refractive index in the direction orthogonal to the slow axis in the plane is ny, the refractive index in the thickness direction is nz, and d represents each thickness (nm).)
<< Production of Second Protective Films A to W >>
<Preparation of cycloolefin polymer film A>
In a nitrogen atmosphere, 500 parts of dehydrated cyclohexane, 1.2 parts of 1-hexene, 0.15 part of dibutyl ether, and 0.30 part of triisobutylaluminum were mixed in a reactor at room temperature, and then kept at 45 ° C. 20 parts of tricyclo [4.3.0.12,5] deca-3,7-diene (dicyclopentadiene, hereinafter abbreviated as DCP), 1,4-methano-1,4,4a, 9a-tetrahydrofluorene ( Hereinafter, a norbornene-based monomer comprising 140 parts of MTF) and 40 parts of 8-methyl-tetracyclo [4.4.0.12, 5.17,10] -dodec-3-ene (hereinafter abbreviated as MTD). The mixture and 40 parts of tungsten hexachloride (0.7% toluene solution) were continuously added over 2 hours for polymerization. To the polymerization solution, 1.06 part of butyl glycidyl ether and 0.52 part of isopropyl alcohol were added to deactivate the polymerization catalyst and stop the polymerization reaction.

  Next, 270 parts of cyclohexane is added to 100 parts of the reaction solution containing the obtained ring-opening polymer, and further 5 parts of a nickel-alumina catalyst (manufactured by JGC Chemical Co., Ltd.) is added as a hydrogenation catalyst. The mixture was heated to 200 ° C. while being pressurized and stirred, and then reacted for 4 hours to obtain a reaction solution containing 20% of a DCP / MTF / MTD ring-opening polymer hydrogenated polymer. After removing the hydrogenation catalyst by filtration, a soft polymer (manufactured by Kuraray; Septon 2002) and an antioxidant (manufactured by Ciba Specialty Chemicals; Irganox 1010) are added and dissolved in the resulting solutions, respectively. (Both 0.1 parts per 100 parts polymer). Next, cyclohexane and other volatile components, which are solvents, are removed from the solution using a cylindrical concentration dryer (manufactured by Hitachi, Ltd.), the hydrogenated polymer is extruded in a strand form from an extruder in a molten state, and pellets after cooling. And recovered. When the copolymerization ratio of each norbornene monomer in the polymer was calculated from the composition of residual norbornenes in the solution after polymerization (by gas chromatography method), it was almost charged at DCP / MTF / MTD = 10/70/20. It was equal to the composition. This hydrogenated ring-opened polymer had a weight average molecular weight (Mw) of 31,000, a molecular weight distribution (Mw / Mn) of 2.5, a hydrogenation rate of 99.9%, and a Tg of 134 ° C.

  The obtained pellets of the ring-opened polymer hydrogenated product were dried at 70 ° C. for 2 hours using a hot air dryer in which air was circulated to remove moisture. Next, the pellets were subjected to a short shaft extruder having a coat hanger type T die with a lip width of 1.6 m (Mitsubishi Heavy Industries, Ltd .: screw diameter 90 mm, T die lip material was tungsten carbide, peel strength from molten resin 44 N ) Was used to produce a cycloolefin polymer film having a thickness of 100 μm. Extrusion molding was performed in a clean room of class 10,000 or less under molding conditions of a molten resin temperature of 240 ° C. and a T die temperature of 240 ° C. The obtained cycloolefin polymer film was stretched 1.5 times in the width direction at a stretching temperature of 135 ° C. using a tenter device shown in FIG. At that time, the length of the tenter device, the clip interval, and the tension of the clip were adjusted so that the orientation angle deviation between the in-plane slow axis of the film and the width direction of the film was within ± 0.4 °. Thereafter, both ears were slit, processed into a film thickness of 30 μm and a width of 1.5 m, and wound into a roll. Moreover, the polyester film was wound up together as a protective film when winding up.

<Production of cycloolefin polymer films B to O and R to W>
A cycloolefin polymer film was prepared in the same manner as the cycloolefin polymer film A, and the stretching conditions and film thicknesses by the tenters shown in Table 1 were changed as appropriate. Cycloolefins having the retardations shown in Tables 2 and 3 were used. Olefin polymer films B to O and R to W were prepared.

<Preparation of cellulose ester film P>
A cellulose ester film P as a second protective film was produced according to the following.

(Preparation of dope solution A)
Cellulose ester (cellulose triacetate synthesized from linter cotton)
100 parts by mass (Mn = 148000, Mw = 310000, Mw / Mn = 2.1)
Triphenyl phosphate 9.5 parts by mass Ethylphthalyl ethyl glycolate 2.2 parts by mass Methylene chloride 440 parts by mass Ethanol 40 parts by mass Azumi filter paper No. 1 manufactured by Filter Paper Co., Ltd. 24, and the dope liquid B was prepared. The dope solution A was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. in the film production line. (A part of the dope solution A was also used for preparing the following inline additive solution A.)
(Silicon dioxide dispersion A)
Aerosil 200V (manufactured by Nippon Aerosil Co., Ltd.) 2 parts by mass (average diameter of primary particles 12 nm, apparent specific gravity 100 g / liter)
18 parts by mass or more of ethanol was stirred and mixed with a dissolver for 30 minutes, and then dispersed with Manton Gorin. The liquid turbidity after dispersion was 100 ppm. 18 parts by mass of methylene chloride was added to the silicon dioxide dispersion with stirring, and the mixture was stirred and mixed with a dissolver for 30 minutes to prepare a silicon dioxide dispersion dilution A.

(Preparation of inline additive solution A)
Methylene chloride 100 parts by weight Dope solution A 34 parts by weight Tinuvin 109 (manufactured by Ciba Specialty Chemicals) 5 parts by weight Tinuvin 171 (manufactured by Ciba Specialty Chemicals) 5 parts by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 3 parts by mass or more was put into a closed container, heated, stirred and completely dissolved and filtered.

  To this, 20 parts by mass of silicon dioxide dispersion diluent A was added with stirring, and the mixture was further stirred for 60 minutes, followed by filtration with Advantech Toyo Co., Ltd. polypropylene wind cartridge filter TCW-PPS-1N. Was prepared.

  In-line additive solution A was filtered with Finemet NF manufactured by Nippon Seisen Co., Ltd. in the in-line additive solution line. Add 2.5 parts by mass of the filtered inline additive A to 100 parts by mass of the filtered dope liquid A, mix thoroughly with an inline mixer (Toray static type in-pipe mixer Hi-Mixer, SWJ), then belt Using a casting apparatus, casting was uniformly performed on a stainless steel band support at a temperature of 35 ° C. and a width of 2.5 m. With the stainless steel band support, the solvent was evaporated until the amount of residual solvent reached 100%, and then peeled off from the stainless steel band support. The solvent is evaporated from the peeled cellulose ester web at 35 ° C., and then 1.2 times in the casting direction (longitudinal direction) and 1.2 times in the width direction using the tenter by utilizing the peripheral speed difference of the transport roll. While stretching, the film was dried at a drying temperature of 130 ° C. At this time, when the stretching was started with a tenter, the residual solvent amount was 11%, and the temperature was 122 ° C. After that, drying is completed while transporting the drying zone at 120 ° C. and 110 ° C. with many rolls, slitting to 2.6 m width, and knurling with a width of 15 mm and an average height of 10 μm is applied to both ends of the film. A cellulose ester film P as a second protective film having a film thickness of 40 μm and a width of 1.5 m was produced by winding it around a 6-inch inner diameter core with a tension of 220 N / m and a final tension of 110 N / m.

<Preparation of cellulose ester film Q>
<Polymer synthesis>
(Synthesis of polymer X)
Polymer X was synthesized with reference to the method described in JP-A-2003-12859. That is, 40 g of a monomer mixture obtained by mixing methyl methacrylate (MMA): 2-hydroxyethyl methacrylate (HEMA) in a ratio of 80:20 to a glass flask equipped with a stirrer, two dropping funnels, a gas introduction tube and a thermometer. Then, 3.0 g of the chain transfer agent mercaptopropionic acid and 30 g of toluene were charged, and the temperature was raised to 90 ° C. Thereafter, 60 g of the monomer mixture was dropped from one dropping funnel over 3 hours, and 0.6 g of azobisisobutyronitrile dissolved in 14 g of toluene was dropped from the other funnel over 3 hours. Thereafter, 0.6 g of azobisisobutyronitrile dissolved in 56 g of toluene was added dropwise over 2 hours, and the reaction was further continued for 2 hours to obtain polymer X. The weight average molecular weight was 8000.

(Synthesis of polymer Y)
Bulk polymerization was performed by the polymerization method described in JP-A No. 2000-344823. That is, the contents were heated to 70 ° C. while introducing the following methyl methacrylate and ruthenocene into a flask equipped with a stirrer, a nitrogen gas inlet tube, a thermometer, an inlet, and a reflux condenser. Next, half of the following β-mercaptopropionic acid which had been sufficiently purged with nitrogen gas was added to the flask under stirring. After the addition of β-mercaptopropionic acid, the contents in the stirring flask were maintained at 70 ° C. and polymerization was carried out for 2 hours. Further, after adding the other half of β-mercaptopropionic acid substituted with nitrogen gas, the temperature of the content being stirred was maintained at 70 ° C., and polymerization was carried out for 4 hours. The temperature of the reaction product was returned to room temperature, and 20 parts by mass of a 5% by mass benzoquinone tetrahydrofuran solution was added to the reaction product to stop the polymerization. While gradually heating the polymer to 80 ° C. under reduced pressure with an evaporator, tetrahydrofuran, residual monomer and residual thiol compound were removed to obtain polymer Y. The weight average molecular weight was 1000.

Methyl methacrylate 100 parts by mass Ruthenocene (metal catalyst) 0.05 parts by mass β-mercaptopropionic acid 12 parts by mass A method for measuring the weight average molecular weight is shown below.

(Weight average molecular weight measurement method)
The weight average molecular weight Mw was measured using gel permeation chromatography.

  The measurement conditions are as follows.

Solvent: Methylene chloride Column: Shodex K806, K805, K803G (Used by connecting three Showa Denko Co., Ltd.)
Column temperature: 25 ° C
Sample concentration: 0.1% by mass
Detector: RI Model 504 (manufactured by GL Sciences)
Pump: L6000 (manufactured by Hitachi, Ltd.)
Flow rate: 1.0ml / min
Calibration curve: Standard polystyrene STK standard polystyrene (manufactured by Tosoh Corp.) Mw = 100000-500 calibration curves with 13 samples were used. Thirteen samples are used at approximately equal intervals.

(Dope solution)
Cellulose triacetate (degree of acetylation: 61.5%, Mn: 110000, Mw / Mn = 2.0) 100 parts by weight Polymer X 10 parts by weight Polymer Y 5 parts by weight Methylene chloride 430 parts by weight Ethanol 40 parts by weight The above dope composition Was put in a sealed container, heated to 70 ° C., and while stirring, cellulose triacetate (TAC) was completely dissolved to obtain a dope. The time required for dissolution was 4 hours. Next, after the dope composition was filtered, the cellulose ester solution whose temperature was adjusted to 33 ° C. was fed to a die and uniformly cast on a stainless steel belt from a die slit to a width of 2.5 m. The cast part of the stainless steel belt was heated from the back with hot water of 37 ° C. After casting, the dope film on the metal support (which is called a web after casting on the stainless steel belt) is dried by applying hot air of 44 ° C., and the residual solvent in the peeling is peeled off at 120 mass%. The film was stretched to a stretching ratio of 1.1 times in the casting direction by applying a tension of, and then adjusted so that the residual solvent amount was 4 mass% and the temperature was 123 ° C., and the web end was gripped with a tenter. The film was stretched so as to have a stretching ratio of 1.1 times in the width direction. After stretching, the film was held for several seconds while maintaining its width, and after the tension in the width direction was relaxed, the width was released and dried at 120 ° C. The cellulose ester film Q, which is a second protective film having a thickness of 41 μm and a width of 1.5 m, produced as described above was wound around a core.

  Subsequently, the following retardation layer was provided on the obtained cycloolefin polymer film and cellulose ester film.

  45% by mass of the compound of the following formula (a)

  45% by mass of the compound of the following formula (b)

  10% by mass of the compound of the following formula (d)

A polymerizable liquid crystal composition (H) comprising: The polymerizable liquid crystal composition (H) had a nematic-isotropic liquid phase transition temperature of 73 ° C. Polymerizability obtained by adding 0.2% of photopolymerization initiator Lucillin TPO (manufactured by Basf) and 0.1% of hindered amine LS-765 (manufactured by Sankyo Lifetech Co., Ltd.) to 99.7% of the polymerizable liquid crystal composition (H). A liquid crystal composition (H1) was prepared. Next, a xylene solution containing 33% of the polymerizable liquid crystal composition (H1) was prepared. This xylene solution was applied on each film in a thickness of 1 to 5 μm by a die coater. The coated film was irradiated with an ultraviolet ray of 250 mJ / mm for 80 seconds at an oxygen concentration of 0.2% and a temperature of 38 ° C. to cure the polymerizable liquid crystal composition (H1) to form a retardation layer. Moreover, Rt was controlled by changing the film thickness as shown in Tables 2 and 3, and retardation layers shown in Tables 2 and 3 were produced. As described above, cycloolefin polymer films A to O and R to W with retardation layers and cellulose ester films P and Q with retardation layers were obtained. Table 4 shows addition amounts (parts by mass) of the polymer X and the polymer Y in the third protective film Q ′, X, X ′, Y, Y ′, and Z.

  Further, the third protection having the retardations shown in Tables 2 and 3 in the same manner as the cellulose ester film Q except that the retardation layer is not provided and the ratio of the polymer X and the polymer Y is changed. Films Q ′, X, X ′, Y, Y ′ and Z were produced.

  As described above, the second protective films A to W with a retardation layer, which are cycloolefin polymer films or cellulose ester films, and the third protective films Q ′, X, X ′, and Y without a retardation layer , Y ′ and Z were prepared.

<Production of polarizing plate>
(Preparation of primer solution)
Hydrogenated product of maleic anhydride modified styrene / butadiene / styrene block copolymer (Tuftec M1913, manufactured by Asahi Kasei Kogyo; melt index value of 4.0 g / 10 min at 200 ° C. and 49 N load, styrene block content 30%, 2 parts of hydrogenation rate 80% or more and maleic anhydride addition amount 2%) are dissolved in a mixed solvent of 8 parts of xylene and 40 parts of methyl isobutyl ketone and filtered through a polytetrafluoroethylene filter having a pore size of 1 μm. It was set as the solution.

(Preparation of polarizing plates 1-33)
A 120 μm-thick polyvinyl alcohol film was immersed in 100 kg of an aqueous solution containing 1 kg of iodine and 4 kg of boric acid and stretched 6 times at 50 ° C. to form a polarizing film having a thickness of 25 μm.

  The second protective films A to O and R to U, which are the prepared cycloolefin polymer films, and the prepared polarizing film are bonded through the prepared primer solution, and the other is heated at 40 ° C. KC4UY (first protective film: manufactured by Konica Minolta Opto Co., Ltd.) that had been saponified with a 5 mol / L sodium hydroxide aqueous solution was bonded and dried using a 5% aqueous solution of all saponified polyvinyl alcohol as an adhesive. A polarizing plate on the viewing side was prepared.

  Further, the cellulose ester films P and Q were alkali-treated with a 2.5 mol / L sodium hydroxide aqueous solution at 40 ° C. for 60 seconds, washed with water for 3 minutes and saponified to obtain an alkali-treated film. The polarizing film and KC4UY (manufactured by Konica Minolta Opto Co., Ltd.) were similarly saponified, and a cellulose ester film P or Q, polarizing film, KC4UY (first saponified polyvinyl alcohol 5% aqueous solution as a pressure-sensitive adhesive) The polarizing plate on the viewing side was prepared by laminating in the order of (protective film).

  Similarly, the third protective film Q ′, X, X ′, Y, Y ′, and Z without the saponified retardation layer and the polarizing film KC4UY (fourth protective film) prepared above are used. A polarizing plate on the backlight side (BL side) was prepared by sequentially stacking.

<Production of liquid crystal display device>
A liquid crystal panel for viewing angle measurement was produced as follows, and the characteristics as a liquid crystal display device were evaluated.

  The pre-bonded polarizing plate of Hitachi liquid crystal television Woo W17-LC50, which is an IPS mode type liquid crystal display device, is peeled off, and the prepared polarizing plate on the viewing side and the BL side is shown in FIG. The IPS mode type liquid crystal display devices 1 to 33 were prepared by pasting on the glass surface of the liquid crystal cell in the configuration of. The in-plane slow axis of the second protective film of the polarizing plate and the alignment direction of the liquid crystal cell were substantially parallel.

<Evaluation of liquid crystal display device>
(Viewing angle)
The viewing angle of the produced liquid crystal display device was measured by EZ-contrast manufactured by ELDIM. As the viewing angle, the contrast between the white display and the black display of the liquid crystal cell was calculated, and the angle at which the contrast was 100 in the oblique direction was defined as the viewing angle.

(Color)
Color measurement at the time of black display was performed with Topcon SR-3A.

Tint measurement was performed between the front and a tilt angle of 60 ° (azimuth angle 45 °) (reference to the front), and ((xx ′) ² + (y−y ′) ² ) ^1/2 was evaluated. .

  * In the formula, front: (x, y), diagonal: (x ', y').

  The results obtained are shown in Table 5.

  In this measurement, the liquid crystal display devices 1 to 23 of the present invention have a viewing angle (contrast of 100 or more) exceeding 50 degrees and smaller than 0.09 of the color change, and are excellent for comparison. I understand.

  Liquid crystal display device no. 34 (Comparative Example) includes a second protective film made of a cycloolefin film having A plate characteristics (nx> ny≈nz) as disclosed in JP-A-2006-126770, and positive C plate characteristics (nz Although it is an example of a liquid crystal display device using a polarizing plate having a retardation layer having> nx≈ny), it is clear that the color change when the viewing angle is changed is not improved.

  Further, even when the liquid crystal display device was lit continuously for 1000 hours, the liquid crystal display device of the present invention did not show corner unevenness in which the four corners look white.

Example 2
Using the protective films A to U with retardation layers prepared in Example 1 and the third protective films Q ′, X, X ′, Y, Y ′ and Z without the retardation layer, the same as in Example 1. A polarizing plate was prepared, and FIG. An IPS mode type liquid crystal display device having the structure described above was manufactured. In this case, the in-plane slow axis of the second protective film of the polarizing plate and the alignment direction of the liquid crystal cell are substantially orthogonal.

  Using the produced IPS mode type liquid crystal display device, the viewing angle and the hue were evaluated in the same manner as in Example 1. As a result, the liquid crystal display device of the present invention was reproduced with excellent contrast and color. It turns out that it has.

Claims (5)

At least a first protective film, a polarizing film, a second protective film made of a thermoplastic polymer containing a cycloolefin resin, and the orientation of the rod-like liquid crystal aligned substantially perpendicular to the surface of the second protective film The fixed retardation layer is a polarizing plate arranged in this order, and the second protective film and the retardation layer are in the environment of 23 ° C. and 55% RH in the equations 2 and 3 at a wavelength of 590 nm. Retardation Ro and Rt represented are respectively
Second protective film: Ro: 30 to 115 nm
Rt: 100 to 250 nm
Rt / Ro: 1.6 to 4.4
Retardation layer: Ro: 0 to 10 nm
Rt: −100 to −400 nm, and the wavelength dispersion characteristic represented by the following formula 1 of the laminate of the second protective film and the retardation layer is 2.0 to 6.5 nm. Polarizing plate.
Formula 1: D (R40) = R40 (630) -R40 (480) (where R40 is a sample placed on a horizontal plane, tilted by 40 ° with the slow axis in the sample plane as the rotation axis, and in the perpendicular direction) (Measured retardation value is represented. (630), (480) represents each measured wavelength (nm).)
Formula 2: Ro = (nx−ny) × d
Formula 3: Rt = ((nx + ny) / 2−nz) × d (wherein the in-plane slow phase of the second protective film or the retardation layer or the laminate of the second protective film and the retardation layer) (The refractive index in the axial direction is nx, the refractive index in the direction orthogonal to the slow axis in the plane is ny, the refractive index in the thickness direction is nz, and d represents each thickness (nm).) The polarizing plate according to claim 1 is disposed so as to sandwich the liquid crystal cell, and has two glass substrates having a rubbing axis in the same direction. A liquid crystal cell substantially parallel to the rubbing axis, and a polarizing plate constituted by a third protective film, a second polarizing film, and a fourth protective film in this order, and claim 1 The in-plane slow axis of the second protective film of the polarizing plate described in 1) and the alignment direction of the liquid crystal molecules are substantially parallel, and the third protective film is Ro: 0 to 5 nm, Rt: −10 10 to 10 nm, and the thickness of the third protective film is 20 to 45 μm. The polarizing plate according to claim 1 is disposed so as to sandwich the liquid crystal cell, and has two glass substrates having a rubbing axis in the same direction. A liquid crystal cell substantially parallel to the rubbing axis, and a polarizing plate constituted by a third protective film, a second polarizing film, and a fourth protective film in this order, and claim 1 The in-plane slow axis of the second protective film of the polarizing plate described in 1) and the alignment direction of the liquid crystal molecules are substantially orthogonal, and the third protective film is Ro: 0 to 5 nm, Rt: −10 to 10 A liquid crystal display device having a thickness of 10 nm and a thickness of the third protective film of 20 to 45 μm. The polarizing plate according to claim 1, wherein the retardation layer is formed using a polymerizable liquid crystal material. The polarizing plate according to claim 4, wherein the polymerizable liquid crystal material is a polymerizable monomer.