JP2009122622A - Thermoplastic film and method of producing the same, heat treatment method, polarizing plate, optical compensation film for liquid crystal display, antireflection film, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic film which reduces the contrast difference over the entire surface and the light suppresses leak when assembled into a large-scale liquid crystal display device. <P>SOLUTION: The thermoplastic film is transversely stretched. Then, a heat-treating zone 46 having the ratio (G/D) between an inter-roll distance (G) and a roll lap length (D) is 0.01 to 3 is conveyed with the ratio (V2/V1) between an exit-side conveying speed (V2) and an entrance-side conveying speed (V1) in the range from 0.6 to 0.999. The thermoplastic film is heat-treated at (Tg-20)°C to (Tg+50)°C, in which Tg is the glass transition temperature of the film. The thermoplastic film exhibits an Rth/Re ratio of at least 0.5 and less than 1, an Rth/Re ratio range of 0.01 to 0.1 in the width direction, and a thermal dimensional change of 0.001% to 0.3% at 80°C for 200 hours. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a thermoplastic film, a method for producing the same, and a heat treatment method. The present invention also relates to a polarizing plate using a thermoplastic film having optical properties, an optical compensation film for a liquid crystal display panel, an antireflection film, and a liquid crystal display device.

  Conventionally, a thermoplastic film has been stretched to develop in-plane retardation and retardation in the thickness direction, and used as a retardation film for a liquid crystal display device to increase the viewing angle. In particular, in recent years, for the development of TN liquid crystal display for television use, a retardation film capable of realizing high contrast when incorporated in a liquid crystal display device is required.

  As a retardation film, a film obtained by stretching a thermoplastic film is known. For example, a method of stretching in the longitudinal (longitudinal) direction (longitudinal stretching), a method of stretching in the lateral (width) direction (lateral stretching), or the longitudinal A method of sequentially performing stretching and transverse stretching (sequential biaxial stretching) and a method of simultaneously performing longitudinal stretching and transverse stretching (simultaneous biaxial stretching) have been performed. However, these methods have problems such as inability to realize high contrast when incorporated in a liquid crystal display device and poor productivity. For example, Patent Document 1 describes a method for producing a retardation film by uniaxial stretching. In the retardation film produced by this method, the slow axis is directed in the vertical direction, and a polarizer and a polarizing plate are used. The roll was not roll-to-roll and the productivity was extremely low. For this reason, Patent Document 2 proposes a film having a slow axis in the horizontal direction and an NZ value of 0.90 to 1.20. Patent Document 3 achieves an NZ value of 0.9 to 1.1 by simultaneously performing transverse stretching and longitudinal relaxation. However, with these methods, as the screen size of the liquid crystal display device increases, a contrast difference (contrast unevenness) becomes apparent between the center and the edge of the screen after the thermo process, and light leakage occurs, and an improvement is desired. It was.

JP 2001-305342 A JP 2007-108529 A JP 2006-133720 A

  In order to solve the above-mentioned problems of the prior art, the present invention provides a thermoplastic film in which no contrast difference occurs and no light leakage occurs when incorporated in a large liquid crystal display device, a heat treatment method thereof, and a thermoplastic film. An object is to provide a manufacturing method.

  Furthermore, it is an object of the present invention to provide a polarizing plate using the thermoplastic film, an optical compensation film for a liquid crystal display panel, an antireflection film, and a liquid crystal display device using these.

  The object of the present invention is achieved by the present invention having the following configuration.

[1] The thermoplastic film heat treatment method according to the present invention is such that, after the thermoplastic film is stretched in the transverse direction, two or more transport rolls have a ratio of roll wrap length (D) to inter-roll length (G) (G / D) in the heat treatment zone arranged at 0.01 or more and 3 or less, the ratio (V2 / V1) of the conveyance speed (V1) on the inlet side and the conveyance speed (V2) on the outlet side is 0.6 or more and 0.999. It is conveyed below.

[2] In [1], the ratio (G / D) of the roll wrap length (D) to the inter-roll length (G) is 0.05 to 0.9.

[3] In [1] or [2], both ends of the film are fixed on a roll.

[4] In any one of [1] to [3], heat treatment is performed at a glass transition temperature (Tg−20) ° C. or more and (Tg + 50) ° C. or less.

[5] In any one of [1] to [4], the transverse stretching (lateral stretching) ratio is 1.1 to 3 times.

[6] In any one of [1] to [5], the thermoplastic film is composed of cellulose acylate, cycloolefin, a lactone ring-containing polymer, and a polycarbonate-based polymer.

[7] In any one of [1] to [6], the thermoplastic film is formed by a melt film forming method.

[8] In any one of [1] to [7], the surface roughness (Ra) of the thermoplastic film is 0.005 μm or more and 0.04 μm or less.

[9] In any one of [1] to [8], the thermoplastic film is formed by a touch roll film forming method.

[10] In any one of [1] to [9], Re of the thermoplastic film after the heat treatment is 50 to 150 (more preferably 70 to 95 nm).

[11] The thermoplastic film according to the present invention has an Rth / Re ratio of 0.5 to less than 1, a range of Rth / Re ratio measured in the width direction of 0.01 to 0.1, and 80 ° C. for 200 hours. The change in the thermal dimension is 0.001% or more and 0.3% or less.

[12] The thermoplastic film according to the present invention is characterized by being prepared by the heat treatment method for a thermoplastic film according to any one of [1] to [10].

[13] The polarizing plate, the optical compensation film for a liquid crystal display panel, the antireflection film, and the liquid crystal display device according to the present invention are characterized by using the above-described thermoplastic film according to the present invention.

[14] In the method for producing a thermoplastic film according to the present invention, after the thermoplastic film is stretched in the transverse direction, two or more transport rolls have a ratio of roll wrap length (D) to inter-roll length (G) (G / D) in the heat treatment zone arranged at 0.01 or more and 3 or less, the ratio (V2 / V1) of the conveyance speed (V1) on the inlet side and the conveyance speed (V2) on the outlet side is 0.6 or more and 0.999. It is conveyed below.

  As described above, according to the thermoplastic film of the present invention, the contrast difference can be reduced over the entire surface when incorporated in a large liquid crystal display device, and light leakage can also be suppressed.

  Moreover, according to the method for producing a thermoplastic film and the heat treatment method according to the present invention, the thermoplastic film having the above-described characteristics can be produced efficiently.

  Furthermore, the polarizing plate, the optical compensation film, the antireflection film, and the liquid crystal display device according to the present invention have excellent optical characteristics.

  In the following, the thermoplastic film of the present invention, its production method, and its use will be described in detail. The description of the constituent elements described below may be made based on typical embodiments of the present invention, but the present invention is not limited to such embodiments. In the present specification, a numerical range represented by using “to” means a range including numerical values described before and after “to” as a lower limit value and an upper limit value.

  First, before explaining the thermoplastic film according to the present invention, referring to FIG. 1 to FIG. 7 regarding a manufacturing apparatus (hereinafter referred to as a film manufacturing apparatus 10) according to the present embodiment for manufacturing a thermoplastic film. While explaining.

  As shown in FIG. 1, the film manufacturing apparatus 10 is an apparatus for manufacturing a thermoplastic film F that can be used for a liquid crystal display device or the like. The pelletized cellulose acylate resin, cycloolefin resin, polycarbonate resin or lactone ring-containing polymer resin, which is the raw material of the thermoplastic film F, is introduced into the dryer 12 and dried, and then the pellet is extruded by the extruder 14. , And supplied to the filter 18 by the gear pump 16. Next, foreign matter is filtered by the filter 18, and molten resin (molten thermoplastic resin) is extruded from the die 20. The molten resin is sandwiched between the first casting roll 28 and the touch roll 24 and press-molded, and then cooled and solidified by the first casting roll 28 to form a film having a predetermined surface roughness. Further, the second casting is performed. The unstretched film Fa is obtained by being conveyed by the roll 26 and the third casting roll 27. This unstretched film Fa may be wound up at this stage, or may be supplied to lateral stretching 36 to 44 that continuously performs long span stretching. Further, even if the unstretched film Fa once wound up is supplied again to the lateral stretching 36 to 44, the same effect can be obtained.

  In the lateral stretching section 42, as shown in FIG. 1, the unstretched film Fa is stretched in the width direction perpendicular to the transport direction to form a lateral stretched film Fb. The preheating part 36 may be provided before the transverse stretching, and the heat fixing part 44 may be provided after the transverse stretching. Thereby, the bowing (shift of the optical axis) during stretching can be reduced. The preheating temperature is preferably higher than the transverse stretching temperature, and the heat setting temperature is preferably lower than the transverse stretching temperature. In other words, the bow is usually concave in the widthwise central portion, but the bowing can be reduced by preheating temperature temperature> stretching temperature, stretching temperature> post heat treatment temperature. Either preheating or post-heat treatment may be performed, or both may be performed.

  A heat treatment is performed after the transverse stretching, where the film is shrunk in the longitudinal direction. In the heat treatment zone 46 in which this is performed, as shown in FIG. 2, the side ends of the laterally stretched film Fc are not gripped by the chuck, and are not contracted in the TD direction (lateral direction) but only contracted in the MD direction (vertical). The transversely stretched film Fb is conveyed by a plurality of rolls 48a to 48d. At this time, as shown in FIG. 3, the plurality of rolls 48 a to 48 d are arranged so that the ratio (G / D) of the roll wrap length (D) to the inter-roll length (G) is 0.01 or more and 3 or less. Is done. This suppresses lateral shrinkage due to the friction between the film and the roll. The film Fc is heat-treated while being transported at a ratio (V2 / V1) of the conveyance speed (V1) of the inlet side roll 48a and the conveyance speed (V2) of the outlet side roll 48d of 0.6 or more and 0.999 or less. Is done. That is, the film Fc is longitudinally contracted in the heat treatment zone.

  The film Fc is heat-treated in the heat treatment zone, whereby the thermoplastic film F, which is the final product with the adjusted orientation angle and retardation, is produced. The film F is taken up by the take-up unit 49.

  Longitudinal stretching may be performed before or after transverse stretching. Longitudinal stretching can be achieved by transporting the film between a pair of nip rolls and increasing the transport speed of the nip roll on the outlet side to be higher than the transport speed of the nip roll on the inlet side. The stretching method differs depending on the distance between the nip rolls (L) and the ratio of the film width W at the longitudinal stretching entrance (L / W), and if L / W is small, JP-A-2005-330411 and JP-A-2006-2006 A longitudinal stretching method as described in Japanese Patent No. 348114 can be employed. This method tends to increase Rth, but can make the apparatus compact. On the other hand, when L / W is large, a longitudinal stretching method as described in JP-A-2005-301225 can be used. Although this method can reduce Rth, the apparatus tends to be long.

  FIG. 4 is a schematic configuration diagram of a liquid crystal display device 50 to which the thermoplastic film F manufactured as described above is applied.

  The liquid crystal display device 50 is configured by sequentially laminating a polarizing plate 52, a liquid crystal cell 54, and a polarizing plate 56, and a light guide plate 60 is attached to the polarizing plate 56 through a diffusion plate 58. Illumination light from the backlight 62 is introduced into the light guide plate 60.

  The polarizing plate 52 is configured by sandwiching a polarizer 66 between an antireflection film 64 and an optical compensation film 68. In the liquid crystal cell 54, a color filter 72 in which R, G, and B pixels are formed is attached to a glass substrate 70, and then a liquid crystal layer 74, a TFT layer 76, and a glass substrate 78 are sequentially arranged. The polarizing plate 56 is configured by sandwiching a polarizer 82 between an optical compensation film 80 and a protective film 84.

  In this case, the thermoplastic film F manufactured by the film manufacturing apparatus 10 shown in FIG. 1 can be used as the antireflection film 64, the optical compensation films 68 and 80, and the protective film 84 constituting the liquid crystal display device 50.

<Features of the present invention>
Next, the thermoplastic film and the manufacturing method thereof according to the present invention will be described in more detail.

  The present invention has been clarified that the decrease in contrast after the thermo treatment originates from the range of the Rth / Re ratio and the Rth / Re ratio, and has reached the present invention. The thermo treatment refers to a drying treatment at 80 ° C. for 200 hours.

  The Rth / Re ratio is preferably from 0.5 to less than 1, more preferably from 0.55 to 0.9, and still more preferably from 0.6 to 0.8. The contrast after the thermo processing is lowered whether the range is exceeded or below.

  In this specification, Re (λ) and Rth (λ) represent in-plane retardation and retardation in the thickness direction at a wavelength λ, respectively. Re (λ) is measured by making light having a wavelength of λ nm incident in the normal direction of the film in KOBRA 21ADH or WR (manufactured by Oji Scientific Instruments). In selecting the measurement wavelength λnm, it can be measured by manually exchanging the wavelength selection filter or by converting the measured value by a program or the like.

  When the film to be measured is represented by a uniaxial or biaxial refractive index ellipsoid, Rth (λ) is calculated by the following method.

  Rth (λ) is obtained by using Re (λ) as an in-plane slow axis (determined by KOBRA 21ADH or WR) as a tilt axis (rotation axis) (in the absence of a slow axis, in the film plane). Any direction is set as the rotation axis), and light of wavelength λ nm is incident from each inclined direction in 10 degree steps from the normal direction to 50 degrees on one side with respect to the film normal direction, and a total of 6 points are measured, KOBRA 21ADH or WR calculates based on the measured retardation value, the assumed value of the average refractive index, and the input film thickness value.

  In the above, in the case of a film having a direction in which the retardation value is zero at a certain tilt angle with the slow axis in the plane from the normal direction as the rotation axis, the retardation value at a tilt angle larger than the tilt angle is After changing its sign to negative, it is calculated by KOBRA 21ADH or WR.

  The retardation value is measured from any two inclined directions with the slow axis as the tilt axis (rotation axis) (in the absence of the slow axis, the arbitrary direction in the film plane is the rotation axis) Rth can also be calculated from the following formula (1) and formula (2) based on the value, the assumed value of the average refractive index, and the input film thickness value.

The above Re (θ) represents a retardation value in a direction inclined by an angle θ from the normal direction. In formula (1), nx represents the refractive index in the slow axis direction in the plane, ny represents the refractive index in the direction perpendicular to nx in the plane, and nz represents the refractive index in the direction perpendicular to nx and ny. . d is the film thickness.
Rth = ((nx + ny) / 2−nz) × d −−−- type (2)

  When the film to be measured cannot be expressed by a uniaxial or biaxial refractive index ellipsoid, that is, a film having no so-called optical axis, Rth (λ) can be calculated by the following method.

  Rth (λ) is the above-mentioned Re (λ), with the in-plane slow axis (determined by KOBRA 21ADH or WR) as the tilt axis (rotation axis), from −50 degrees to +50 with respect to the film normal direction. 11 points of light having a wavelength of λ nm are incident from each tilted direction in steps of 10 degrees up to 5 degrees, and KOBRA 21ADH is measured based on the measured retardation value, the assumed average refractive index, and the input film thickness value. Or, WR is calculated.

  In the above measurement, as the assumed value of the average refractive index, the values in the polymer handbook (John Wiley & Sons, Inc.) and catalogs of various optical films can be used. Those whose average refractive index is not known can be measured with an Abbe refractometer.

  Examples of the average refractive index values of main optical films are as follows: cellulose acylate (1.48), cycloolefin polymer (1.52), polycarbonate (1.59), polymethyl methacrylate (1.49), Polystyrene (1.59). The KOBRA 21ADH or WR calculates nx, ny, and nz by inputting the assumed average refractive index and the film thickness. The NZ value is calculated from NZ = 0.5 + (Rth / Re).

  Further, the range of the Rth / Re ratio measured in the width direction is preferably 0.01 or more and 0.1 or less, more preferably 0.01 or more and 0.09 or less, and further preferably 0.02 or more and 0.08. is there. The range of the Rth / Re ratio refers to the difference between the maximum value and the minimum value of the measured value at a point equally divided into 20 in the width direction. Thereby, even when incorporated in a large screen, unevenness of contrast in the screen after the thermo process can be suppressed.

  If the range of the Rth / Re ratio exceeds this range, the in-plane contrast unevenness increases after the thermo process. On the other hand, below this range, it is not preferable for the following reasons. That is, in order to reduce the range of Rth / Re ratio, it is necessary to increase the amount of longitudinal shrinkage processing described later. Along with this, the film is deformed in the shape of a tin plate in the width direction, which is manifested by thermo processing and increases the unevenness of contrast. This is to make it happen.

  Furthermore, the present invention has revealed that the cause of light leakage after the thermo treatment is caused by the dimensional change of the thermoplastic film before and after the thermo treatment. When a dimensional change occurs in the thermo treatment, a stress derived from the dimensional difference is generated between the glass plate bonded in the liquid crystal display device, which causes a photoelastic change, resulting in light leakage. .

  The thermal dimensional change accompanying the thermo treatment is 0.001% or more and 0.3% or less, more preferably 0.003% or more and 0.25% or less, and further preferably 0.005% or more and 0.2% or less. . If this range is exceeded, light leakage will increase, and if it falls below this range, light leakage will increase. This is because the size of the glass plate also changes, so that a dimensional difference is generated between the glass plate and the glass plate even if it falls below this range.

  The point in preparing such a thermoplastic film is that after the film is stretched in the transverse direction (TD), the ratio (G / D) of roll wrap length (D) to inter-roll length (G) is 0. The heat treatment zone disposed between 01 and 3 or less is heat-treated while being conveyed at a ratio (V2 / V1) of the conveyance speed (V1) on the inlet side to the conveyance speed (V2) on the outlet side of 0.6 or more and 0.999 or less. This is a method for heat-treating a thermoplastic film.

  When an optical film requiring uniformity is produced by transverse stretching, it is carried out with a tenter. As the material is balanced by stretching, the thickness is reduced and neck-in in the orthogonal direction (MD) occurs. However, in the tenter stretching, the film is tensioned in the MD direction so that the neck-in hardly occurs and the thickness is reduced accordingly. As a result, the film is compressed in the thickness direction, the plane orientation advances, Rth increases and becomes larger than Re.

  Thus, Rth> Re immediately after tenter stretching, and by contracting this to MD only, Rth alone can be lowered without lowering Re. That is, when both MD and TD contract, both Re and Rth decrease and Rth> Re. However, when only MD is decreased, the in-plane orientation (Re) does not change, and only the thickness increases and only Rth can be decreased. . As a result, Rth <Re can be realized.

  Such MD shrinkage after stretching for Rth reduction is described in Patent Documents 2 and 3 described above in the tenter after transverse stretching using a simultaneous biaxial stretching machine (while being held by a clip / Patent Documents 2 and 3). Doing the described stretching and longitudinal contraction in the tenter or simultaneously indicates that the lateral stretching is gripped by the clip, indicating that the longitudinal contraction is also gripped by the clip) This is achieved by contracting in the vertical direction. However, in this method, it is necessary to create a gap between adjacent clips in advance so as to be able to contract in the MD direction. As a result, the portion gripped by the clip portion and the portion not gripped between the clips Stretching unevenness occurs and the range of the Rth / Re ratio tends to increase. Along with this, in-plane thermal dimensional change unevenness tends to increase. Uneven thermal dimensional change is not preferable because it easily causes uneven contrast and light leakage. The thermal dimension unevenness is a value obtained by dividing the maximum and minimum values of the 10 thermal dimension changes measured in the MD and TD directions by the average value by dividing into 5 equal parts in the width direction. Is preferable, more preferably 7% or less, still more preferably 5% or less.

  Further, there is a difference in contraction behavior during the contraction process between a pair of clips facing in the width direction and a portion not gripped by the clip. This means that the portion not held by the clip can contract in the TD direction in addition to the contraction in the MD direction. On the other hand, the TD cannot contract at all between the pair of clips. As described above, residual strain accompanying stretching is easily generated in TD, and this causes thermal contraction of TD by the thermo treatment. MD expands to match the material balance with this heat shrinkage. These dimensional changes cause light leakage. In this way, residual strain is likely to occur in the film when it is gripped by the clip at the same time and vertically contracted in the tenter, and this is released in the thermo, and the Rth / Re ratio range and thermal dimensional change after thermo processing, Unevenness in thermal dimensional change was likely to increase.

  On the other hand, in the present invention, after the transverse stretching is finished and exits from the tenter (after being removed from the chuck), it is contracted in the vertical direction and is not contracted in the tenter. That is, since both ends are not gripped by the chuck, it can be vertically contracted uniformly over the entire width. For this reason, the range of the Rth / Re ratio is unlikely to increase, and variation in the thermal dimension can be suppressed.

  Thus, it is a point of the present invention that only MD (vertical) contraction is caused without contracting in the TD direction without being gripped by the chuck. In order to shrink only MD and not TD, in the present invention, a thermoplastic film is passed through a plurality of rolls arranged in the heat treatment zone while being wrapped. Thereby, shrinkage in the TD direction can be suppressed by the friction between the roll and the film. At this time, the conveyance speed (V1) on the inlet side is delayed from the conveyance speed on the outlet side, and V2 / V1 is 0.6 or more and 0.999 or less, more preferably 0.65 or more and 0.99 or less, and more preferably 0.8. Only MD can be shrunk by setting it to 65 or more and 0.95 or less, more preferably 0.7 or more and 0.85 or less. If this range is exceeded, longitudinal shrinkage cannot be achieved, and Rth / Re exceeds the range of the present invention. Below this range, the thermoplastic film slips on the roll and scratches are generated, which is not preferable. Such V2 / V1 can be achieved by delaying the roll conveyance speed on the inlet side from the roll conveyance speed on the outlet side.

  In order to obtain the frictional force necessary to suppress the TD shrinkage of the film, the ratio (G / D) of the length (D) of the film wrapping on the roll and the length (G) between the rolls is 0. It is preferably 0.01 or more and 3 or less, more preferably 0.03 or more and 1 or less, and still more preferably 0.05 or more and 0.5 or less. If this range is exceeded, the distance between rolls becomes longer, the frictional force decreases, TD shrinkage occurs, Re decreases, and Rth / Re exceeds the range of the present invention. Furthermore, the range of the Rth / Re ratio and unevenness of heat shrinkage are also unfavorable. This is because if the distance between the rolls is long, both ends of the film are more easily contracted than the center (if the film is divided into three at the center and both ends, the center is constrained by both ends, but both ends are centered at one end. However, the range of the Rth / Re ratio and the thermal shrinkage unevenness are likely to increase.

  On the other hand, if the ratio (G / D) is less than this range, shrinkage in the TD direction does not occur at all and residual strain is likely to occur in the film. As a result, thermal shrinkage of TD and accompanying MD elongation occur, Thermal dimensional changes are not preferred beyond the scope of the present invention. That is, by causing a slight lateral (TD) contraction in addition to the vertical contraction, it is possible to suppress the occurrence of thermal dimensional changes and thermal dimensional change irregularities. Such a thermal dimensional change causes light leakage as described above. Furthermore, the range of the Rth / Re ratio increases, which is not preferable. This is because the length that can be longitudinally contracted is not sufficient, and the entire surface cannot be uniformly contracted longitudinally, causing unevenness in Re and Rth and increasing the range of the Rth / Re ratio.

  In order to obtain a sufficient frictional force between the roll and the thermoplastic film, the surface roughness (Ra) of the thermoplastic film is preferably 0.005 μm or more and 0.04 μm or less, more preferably 0.007 μm or more and 0.035 μm or less, More preferably, they are 0.009 micrometer or more and 0.030 micrometer or less. If this range is exceeded, sufficient frictional force will not be generated, and Rth / Re will exceed the range of the present invention. On the other hand, if it falls below this range, scratches will occur due to stagnation with the roll, and almost no relaxation in the TD direction will occur. Undesirably, the thermal dimensional change increases, resulting in light leakage. This surface roughness refers to a value obtained by measuring a thermoplastic film after stretching and longitudinal shrinkage. Originally, the surface roughness during the longitudinal shrinkage treatment is reflected in the frictional force, but since the surface roughness does not change before and after the longitudinal shrinkage treatment, the value after the longitudinal shrinkage was used.

  A film having such a surface can be achieved by a touch roll film forming method described later. This is because the film immediately after casting is sandwiched between rolls with smooth surfaces from both sides, so that higher smoothness can be achieved compared to the case where the film is not used, and the above-mentioned surface roughness can be realized.

  In the case of performing such vertical shrinkage, the number of rolls is preferably 2 or more and 100 or less, more preferably 3 or more and 50 or less, and still more preferably 4 or more and 20 or less. The diameter of the preferable roll is preferably 5 cm to 100 cm, more preferably 10 cm to 80 cm, and still more preferably 15 cm to 60 cm.

  Furthermore, in the present invention, it is preferable to fix both ends of the film on a roll. “Fix” refers to setting the dimensional change in the width direction to 10% or less. For this purpose, electrostatic application may be performed on both ends or the entire width of the roll, or suction may be performed using both ends or the entire surface of the roll as suction drums. Further, a nip roll may be installed on the roll over the end or the entire width, and the film may be fixed. The number of nip rolls is preferably 1 or more and 20 or less, more preferably 2 or more and 10 or less on one roll. Furthermore, it is also preferable that the roll is an expander roll. These methods may be carried out alone or in combination.

  The longitudinal shrinkage temperature is preferably a glass transition temperature (Tg-20) ° C. or more and (Tg + 50) ° C. or less, more preferably (Tg−10) ° C. or more (Tg + 40) ° C. or less, and further preferably (Tg−5) ° C. or more ( Tg + 35) ° C. or lower. Beyond this range, Re tends to decrease and Rth / Re tends to exceed 1. On the other hand, below this range, Rth and Re do not decrease and Rth / Re exceeds the range of the present invention. Further, the residual strain during stretching cannot be sufficiently eliminated, and the thermal dimensional change increases and light leakage tends to increase.

  Such longitudinal shrinkage may be heated through a heat medium inside a roll through which the thermoplastic film passes, or may be heated from a heat source (IR heater, halogen heater, etc.) installed on the upper side of the thermoplastic film, and temperature control. You may implement in the heat processing zone which introduce | transduced the wind.

  The time required for such shrinkage treatment is not particularly limited, but is preferably 1 second to 10 minutes, more preferably 5 seconds to 8 minutes, and further preferably 10 seconds to 5 minutes.

  The Re of the thermoplastic film thus obtained is preferably 20 nm to 300 nm, more preferably 30 nm to 280 nm, still more preferably 40 nm to 250 nm, particularly preferably 50 nm to 150 nm, most preferably 70 nm to 95 nm. It is.

Further, the thermoplastic film obtained after the heat treatment of the present invention may satisfy the optical characteristics of the region specified by the following two formulas.
Rth = (− 3/8) Re + 80
Rth = (− 3/8) Re + 100
(However, Re is −10 to 150 nm, particularly preferably 50 nm to 150 nm, and most preferably 70 nm to 95 nm.)

  Below, the present invention will be explained step by step.

(1) Material of thermoplastic film The thermoplastic film used in the present invention is not particularly limited, but preferred examples include cellulose acylate, lactone ring-containing polymer, cyclic olefin, and polycarbonate. Of these, cellulose acylate and cyclic olefin are preferred, cellulose acylate containing an acetate group and propionate group, and cyclic olefin obtained by addition polymerization, more preferably cyclic olefin obtained by addition polymerization. It is.

(A) Cellulose acylate As the cellulose acylate, for example, those described in JP-A-2001-188128, JP-A-2006-142800, and JP-A-2007-99817 can be used, and the total acyl substitution degree is 2.1 or more. 3.0 or less is preferable, and the substitution degree of the acetyl group is preferably 0.05 or more and 2.5 or less, more preferably 0.05 or more and 0.5 or less, or 1.5 or more and 2.5 or less. The propionyl substitution degree is preferably 0.1 or more and 2.8 or less, more preferably 0.1 or more and 1.2 or less, or 2.3 or more and 2.8 or less.

(B) Cyclic olefin The cyclic olefin is preferably polymerized from a norbornene-based compound. This polymerization can be carried out by either ring-opening polymerization or addition polymerization. Examples of addition polymerization include those described in Japanese Patent No. 3517471, Japanese Patent No. 3559360, Japanese Patent No. 3867178, Japanese Patent No. 3877721, Japanese Patent No. 3907908, Japanese Patent No. 3945598, Japanese Patent Publication No. 2005-527696, Japanese Patent Laid-Open No. 2006-2006. No. 28993 and International Publication No. 2006/004376 pamphlet. Particularly preferred is the one described in Japanese Patent No. 3517471.

  As the ring-opening polymerization, WO 98/14499 pamphlet, Japanese Patent No. 30605532, Japanese Patent No. 3320478, Japanese Patent No. 3273046, Japanese Patent No. 3404027, Japanese Patent No. 3428176, Japanese Patent No. 3687231, Japanese Patent No. 3873934, Patent No. 3912159 is mentioned. Among them, those described in WO98 / 14499 pamphlet and Japanese Patent No. 30605532 are preferable.

  Of these cyclic olefins, those of addition polymerization are more preferred.

(C) Lactone ring-containing polymer This refers to a polymer having a lactone ring structure represented by the following general formula (1).

In the general formula ^{(1), R 1, R} 2, R 3 each independently represent a hydrogen atom or an organic residue having 1 to 20 carbon atoms. The organic residue may contain an oxygen atom.

  The content of the lactone ring structure of the general formula (1) is preferably 5 to 90% by weight, more preferably 10 to 70% by weight, and still more preferably 10 to 50% by weight.

  In addition to the lactone ring structure represented by the general formula (1), at least selected from (meth) acrylic acid esters, hydroxyl group-containing monomers, unsaturated carboxylic acids, and monomers represented by the following general formula (2a) A polymer structural unit (repeating structural unit) constructed by polymerizing one kind is preferred.

In the general formula (2a), R ⁴ represents a hydrogen atom or a methyl group, X represents a hydrogen atom, an alkyl group having 1 to 20 carbon atoms, an aryl group, -OAc group, -CN group, -CO-R ⁵ group, or an -C-O-R ⁶ group, Ac group represents an acetyl group, R ⁵ and R ⁶ represents a hydrogen atom or an organic residue having 1 to 20 carbon atoms.

  For example, those described in International Publication No. 2006/025445, JP 2007-70607 A, JP 2007-63541 A, JP 2006-171464 A, and JP 2005-162835 A can be used. .

(D) Polycarbonate resin A resin obtained by reacting a dihydroxy component and a carbonate precursor by an interfacial polymerization method or a melt polymerization method. For example, those described in JP-A-2006-277914 and JP-A-2006-106386 And those described in JP-A-2006-284703 can be preferably used.

(E) Additives In these thermoplastic films, 0 to 20% by mass of alkylphthalylalkyl glycolates, phosphate esters, carboxylic acid esters, and polyhydric alcohols can be added as plasticizers. Phosphite stabilizers (for example, tris (4-methoxy-3,5-diphenyl) phosphite, tris (nonylphenyl) phosphite, tris (2,4-di-t-butylphenyl) phosphite), Phenolic stabilizers (eg, 2,6-di-t-butyl-4-methylphenol, 2,2-methylenebis (4-ethyl-6-t-butylphenol), 2,5-di-t-butylhydroquinone, Pentaerythrityltetrakis [.3- (3,5-di-tert-butyl-4-hydroxyphenyl) propiolate, 4,4-thiobis- (6-tert-butyl-3-methylphenol), 1,1 ^, -Bis (4-hydroxyphenyl) cyclohexane, octadecyl-3- (3,5-di-t-butyl-4-hydroxyphenyl) propiolet 0 to 3 mass% of epoxy compounds and thioether compounds can be added, and 0 to 1000 ppm of inorganic fine particles such as silica, titania, zirconia, alumina, calcium carbonate, and clay, and organic fine particles such as crosslinked acryl and crosslinked styrene are added as a matting agent. In addition, ultraviolet absorbers (for example, 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2,2, -methylenebis [4- (1,1,3,3-tetramethylbutyl) -6- [ It is also preferable to add (2H-benzotriazol-2-yl) phenol]]), an infrared absorber or a retardation modifier.

(2) Film formation of thermoplastic film The film used in the present invention can be used by either melt film formation or solution film formation, but more preferably by the melt film formation method.

(A) Melt film forming method i) Pelletization It is preferable that the thermoplastic resin and the additive are mixed and pelletized prior to melt film formation.

  Pelletization is made by drying the thermoplastic resin and additives, melting at 150 ° C to 300 ° C using a twin-screw kneading extruder, and then extruding into noodles in air or water and cutting. it can. Further, pelletization may be performed by an underwater cutting method or the like that is cut while being directly extruded from a die after being melted by an extruder.

  As the extruder, a single screw extruder, a non-meshing type opposite direction rotating twin screw extruder, a meshing type different direction rotating twin screw extruder, a meshing type same direction rotating twin screw extruder, or the like can be used. The number of revolutions of the extruder is preferably 10 rpm to 1000 rpm, more preferably 20 rpm to 700 rpm. The extrusion residence time is 10 seconds or more and 10 minutes or less, more preferably 20 seconds to 5 minutes or less.

Preferably, the pellet size is such is preferably 10mm ³ ~1000mm ^3, more preferably 30 mm ³ 500 mm ^3.

ii) Kneading and melting It is preferable to reduce moisture in the pellets prior to melt film formation. A preferable drying temperature is 40 to 200 ° C, more preferably 60 to 150 ° C. Thereby, the water content is preferably 1.0% by mass or less, and more preferably 0.1% by mass or less.

  The dried pellets are fed into the cylinder via the feed port of the extruder, kneaded and melted. The inside of the cylinder is composed of a supply unit (region A), a compression unit (region B), and a metering unit (region C) in order from the supply port side. The screw compression ratio of the extruder is preferably 1.5 to 4.5, the ratio of the cylinder length to the cylinder inner diameter (L / D) is preferably 20 to 70, and the cylinder inner diameter is preferably 30 mm to 150 mm. The extrusion temperature is preferably 190 to 300 ° C. Furthermore, in order to prevent the molten resin from being oxidized by residual oxygen, it is also preferable to carry out the inside of the extruder in an inert (nitrogen or the like) air flow or while evacuating using a vented extruder.

iii) Filtration It is preferable to provide a filtration device incorporating a breaker plate type filtration or a leaf type disk filter for the filtration of foreign matters in the resin. Filtration may be performed in a single stage or multistage filtration. The filtration accuracy is preferably 15 μm to 3 μm, and more preferably 10 μm to 3 μm. The filter medium is preferably made of stainless steel. As the structure of the filter medium, a knitted wire or a sintered metal powder (sintered filter medium) can be used, and among them, a sintered filter medium is preferable.

iv) Gear pump It is preferable to provide a gear pump between the extruder and the die in order to reduce the fluctuation of the discharge amount and improve the thickness accuracy. As a result, the resin pressure fluctuation range in the die can be within ± 1%.

  In order to improve the quantitative supply performance by the gear pump, a method of controlling the pressure before the gear pump to be constant by changing the number of rotations of the screw can also be used.

v) Die Melted by the extruder configured as described above, and the molten resin is continuously fed to the die via a filter and a gear pump as necessary. The die may be any of a T die, a fish tail die, and a hanger coat die. It is also preferable to insert a static mixer immediately before the die in order to increase the uniformity of the resin temperature. The clearance at the exit of the T-die is generally 1.0 to 10 times the film thickness, preferably 1.2 to 5 times.

  The die is preferably adjustable in thickness at intervals of 5 to 50 mm. An automatic thickness adjustment die that calculates downstream film thickness and thickness deviation and feeds back the results to die thickness adjustment is also effective. In addition to the single layer film forming apparatus, it is also possible to manufacture using a multilayer film forming apparatus.

  Thus, the residence time from when the resin enters the extruder through the supply port until it exits from the die is preferably 3 to 40 minutes, more preferably 4 to 30 minutes.

vi) Cast The molten resin (melt) extruded from the die onto the sheet is cooled and solidified on the casting drum to obtain a film.

  At this time, it is preferable to shield between the die and the casting drum to suppress the influence of wind.

  When the melt contacts the casting drum, it is preferable to use an electrostatic application method, an air knife method, an air chamber method, a vacuum nozzle method, a touch roll method, etc., to increase the adhesion between the casting drum and the melt, and in particular, the touch roll method is used. preferable. Such an adhesion improving method may be performed on the entire surface of the melt or may be performed on a part thereof.

  The touch roll method is a method of shaping a film surface by placing a touch roll on a cast drum. At this time, the touch roll is not usually high in rigidity but preferably has elasticity. Thereby, it can suppress that a surface unevenness | corrugation makes below the range of this invention ease by an excessive surface pressure. For this purpose, it is necessary to make the outer cylinder thickness of the roll thinner than that of a normal roll, and the outer wall thickness Z is preferably 0.05 mm to 7.0 mm, more preferably 0.2 mm to 5 mm. 0.0 mm, more preferably 0.3 mm to 3.5 mm. The touch roll may be installed on a metal shaft and a heat medium (fluid) may be passed between them. An elastic layer is provided between the outer cylinder and the metal shaft, and the heat medium (fluid) is filled between the outer cylinders. Can be mentioned. A weaker pressing with a touch roll is preferable because Rth can be reduced more, but if it is too small, the surface roughness of the present invention cannot be achieved. On the other hand, if it is too large, the surface roughness decreases but Rth tends to increase. For this reason, the surface pressure of the touch roll is preferably 0.1 MPa to 5 MPa, more preferably 0.2 MPa to 3 MPa, and still more preferably 0.3 MPa to 2 MPa. Here, the surface pressure is a value obtained by dividing the force pressing the touch roll by the contact area between the thermoplastic film and the touch roll.

  The temperature of the touch roll is preferably set to 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, and still more preferably 80 ° C to 140 ° C. Such temperature control can be achieved by passing a temperature-controlled liquid or gas through these rolls. Thus, what has a temperature control mechanism inside is more preferable.

  The material of the touch roll is preferably a metal, more preferably stainless steel, and the surface is preferably plated. On the other hand, a rubber roll or a metal roll lined with rubber is not preferable because the rubber surface has irregularities and the thermoplastic film having the surface irregularities cannot be formed.

  The surface of the touch roll and casting roll has an arithmetic average height Ra of 100 nm or less, preferably 50 nm or less, and more preferably 25 nm or less.

  For example, JP-A-11-314263, JP-A-2002-36332, JP-A-11-235747, WO97 / 28950, JP-A-2004-216717, JP-A-2003-145609 are touch rolls. Can be used.

  More preferably, a plurality of casting drums (rolls) are used for slow cooling (of which the touch roll is arranged so as to touch the first casting roll on the most upstream side (closer to the die)). In general, it is relatively common to use three cooling rolls, but this is not a limitation. The diameter of the roll is preferably 100 mm to 1500 mm, more preferably 150 mm to 1000 mm. The interval between the plurality of rolls is preferably 0.3 mm to 300 mm, more preferably 1 mm to 100 mm, and still more preferably 3 mm to 30 mm. The casting drum is preferably 60 ° C to 160 ° C, more preferably 70 ° C to 150 ° C, still more preferably 80 ° C to 140 ° C.

  Then, it peels off from a casting drum, winds up after passing through a nip roll. The winding speed is preferably 10 m / min to 100 m / min, more preferably 15 m / min to 80 m / min, still more preferably 20 m / min to 70 m / min.

  The film forming width is preferably 0.7 m to 3 m, and more preferably 1 m to 2 m. The thickness after film formation (unstretched) is preferably 40 μm to 300 μm, more preferably 60 μm to 250 μm, and still more preferably 80 μm to 200 μm.

vii) Trimming, thickness increasing processing, winding After the film is formed in this way, it is also preferable to trim both ends. The portion cut off by trimming may be crushed and used again as a raw material.

  Further, it is also preferable to perform a thickness increasing process (knurling process) on one or both ends. The height of the unevenness due to the thickness increasing process is preferably 1 μm to 50 μm, more preferably 3 μm to 20 μm. Thickening processing may be convex on both sides or convex on one side. The width of the thickness increasing process is preferably 1 mm to 50 mm, more preferably 3 mm to 30 mm. Extrusion can be performed at room temperature to 300 ° C.

  It is also preferable to apply a lami film on one or both sides before winding. The thickness of the laminate film is preferably 5 μm to 100 μm, more preferably 10 μm to 50 μm. The material is not particularly limited, such as polyethylene, polyester, and polypropylene.

  A preferable winding tension is 2 kg / m width to 50 kg / width, more preferably 5 kg / m width to 30 kg / width.

(Solution casting)
i) Dissolution In solution casting, a solvent is selected according to the thermoplastic resin to be used, and a highly concentrated resin solution (dope) is prepared. A dichloromethane solvent is preferably used for cellulose acylate and polycarbonate, and for example, the solvent described in paragraph [0044] of JP-A No. 2001-188128 can be used. In the case of cycloolefin, dichloromethane and hydrocarbon solvents (toluene, xylene, benzene, cyclohexane, etc.) can be used. For example, those described in paragraph [0180] of JP-A-2007-108529 can be used.

  The concentration of the thermoplastic resin in these dopes is preferably 5% by mass or more and 40% by mass or less, and more preferably 10% by mass or more and 30% by mass or less. At this time, it is preferable to dissolve the above-mentioned additives together.

  A cooling / heating method may be used for dissolution. For the cooling / heating method, methods disclosed in JP-A-11-323017, JP-A-10-67860, JP-A-10-95854, JP-A-10-324774, and JP-A-11-302388 are used. be able to.

ii) Solution casting After the prepared dope is temporarily stored and degassed, it is supported through a high-precision pump (for example, a pressurized metering gear pump) to a pressure die to support a casting part that runs endlessly from a feed base (slit) Cast evenly on the body (band, drum). At this time, the casting may be performed in a single layer, or two or more types may be cast. The raw dry dope film (also referred to as web) is peeled off at the peeling point where the support has almost gone around. The support (band, drum) is preferably kept at -30 ° C to 30 ° C. Clip the both ends of the peeled web with clips, transport it with a tenter while holding the width, dry it, then transport it with a roll group of drying equipment, dry it, trim it, and then knurling (embossing) Wind up to a predetermined length with a take-off machine.

  The film forming width is preferably 0.7 m to 3 m, and more preferably 1 m to 2 m. The thickness after film formation (unstretched) is preferably 40 μm to 300 μm, more preferably 60 μm to 250 μm, and still more preferably 80 μm to 200 μm.

  Such a solution casting can also use the method described in the public technique (public technical number 2001-1745, published on March 15, 2001, Invention Association).

[Stretching process]
The thermoplastic film thus melt-formed and solution-formed is stretched transversely. A preferable draw ratio is 1.1 times or more and 3 times or less, more preferably 1.2 times or more and 2.5 times or less, and further preferably 1.3 times or more and 2.3 times or less. The draw ratio refers to a value obtained by dividing the length after stretching by the length before stretching.

  The stretching temperature is preferably (Tg−10) ° C. or more and (Tg + 50) ° C., more preferably (Tg−5) ° C. or more and (Tg + 40) ° C. or less, and further preferably Tg or more and (Tg + 30) ° C. or less.

  It is also preferable to combine longitudinal stretching with one or both of such lateral stretching. The preferred longitudinal stretching temperature is (Tg-10) ° C. or higher and (Tg + 40) ° C. or lower, more preferably Tg or higher (Tg + 20) ° C. or lower. The preferred draw ratio is 1.05 times or more and 2.5 times or less, more preferably 1.1 times or more and 1.8 times or less, but is preferably smaller than the transverse draw ratio, and more preferably 0. 8 times or less.

  It is necessary to carry out these stretching operations without containing residual solvent (0.1% by mass or less). This is because if the residual solvent is included, volatilization unevenness from the film surface occurs and the range (variation) of the Rth / Re ratio increases.

  The thickness of the film after stretching is preferably 20 μm to 150 μm, more preferably 30 μm to 120 μm, and still more preferably 40 μm to 100 μm.

[Vertical contraction]
The stretched film is longitudinally shrunk as described above. This may be performed online following stretching, or may be performed after winding once after stretching.

[Film processing]
The thermoplastic film of the present invention thus obtained may be used alone, or may be used in combination with a polarizing plate, and a liquid crystal layer or a layer with a controlled refractive index (low reflection layer) on these. ) Or a hard coat layer may be used. These can be achieved by the following steps.

(surface treatment)
(1) Cellulose acylate film By performing a surface treatment, adhesion to each functional layer (for example, an undercoat layer and a back layer) can be improved. For example, glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali saponification treatment can be used. The glow discharge treatment here includes a low temperature plasma treatment performed under a low pressure gas of 10 ^{−3 to} 20 Torr (0.13 to 2700 Pa). Further, plasma treatment under atmospheric pressure is also a preferable glow discharge treatment.

  Of these, alkali saponification is particularly preferable.

  The alkali saponification treatment may be immersed in a saponification solution (immersion method) or a saponification solution may be applied (application method). In the case of the dipping method, it is achieved by passing an aqueous solution of pH 10 to 14 such as NaOH or KOH through a bath heated to 20 ° C. to 80 ° C. for 0.1 to 10 minutes, and then neutralizing, washing with water and drying. it can.

  In the case of the coating method, a dip coating method, a curtain coating method, an extrusion coating method, a bar coating method, and an E-type coating method can be used. As the solvent for the alkali saponification coating solution, an alcohol solvent is preferably used to improve wettability, and isopropyl alcohol is particularly preferable. An aqueous solution of a surfactant can also be used as a solvent. As the alkali in the alkali saponification coating solution, KOH, NaOH or the like can be used. The pH of the saponification coating solution is preferably 10 or more, more preferably 12 or more. The saponification conditions are preferably 5 seconds to 5 minutes at room temperature, particularly preferably 20 seconds to 3 minutes. It is preferable to wash with water after the saponification reaction. The coating-type saponification treatment and the alignment film uncoating described later can be performed continuously, and the number of steps can be reduced. These saponification methods can be described in, for example, JP-A No. 2002-82226 and WO 02/46809 pamphlet.

  It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be coated after the surface treatment or may be coated without the surface treatment. Details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention).

  These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

(2) Thermoplastic film of the present invention other than cellulose acylate The thermoplastic film of the present invention other than cellulose acylate can be subjected to glow discharge treatment, ultraviolet irradiation treatment, corona treatment, flame treatment, acid or alkali treatment. . The glow discharge treatment here includes a low temperature plasma treatment performed under a low pressure gas of 10 ^{−3 to} 20 Torr (0.13 to 2700 Pa). Further, plasma treatment under atmospheric pressure is also a preferable glow discharge treatment.

  Among these, glow discharge treatment, corona treatment, and flame treatment are preferable, and corona treatment is more preferable.

  It is also preferable to provide an undercoat layer for adhesion to the functional layer. This layer may be coated after the surface treatment or may be coated without the surface treatment. Details of the undercoat layer are described on page 32 of the Japan Society for Invention and Innovation (Public Technical Number 2001-1745, published on March 15, 2001, Japan Institute of Invention).

  These surface treatment and undercoating processes can be incorporated at the end of the film forming process, can be performed alone, or can be performed in the functional layer application process described later.

(Grant functional layer)
The thermoplastic film of the present invention is provided with a functional layer described in detail on pages 32 to 45 in the Japan Society of Invention Disclosure Technical Bulletin (Public Technical No. 2001-1745, published on March 15, 2001, Japan Society of Invention and Innovation). It is preferable to combine them. Among these, application of a polarizing layer (polarizing plate), application of an optically anisotropic layer (optical compensation layer), and application of an antireflection layer (antireflection film) are preferable.

<Optically anisotropic layer>
The optically anisotropic layer is preferably designed so as to compensate for the liquid crystalline compound in the liquid crystal cell in the black display of the liquid crystal display device. The alignment state of the liquid crystal compound in the liquid crystal cell in black display varies depending on the mode of the liquid crystal display device. The alignment state of the liquid crystal compound in the liquid crystal cell is described in IDW'00, P411 to 414 of FMC7-2, and the like.

  The optically anisotropic layer is formed directly from the liquid crystalline compound on the support or from the liquid crystalline compound via an alignment film. The alignment film preferably has a thickness of 10 μm or less.

  The liquid crystalline compound used for the optically anisotropic layer includes a rod-like liquid crystalline compound and a discotic liquid crystalline compound. The rod-like liquid crystal compound and the discotic liquid crystal compound may be a high-molecular liquid crystal or a low-molecular liquid crystal, and further include those in which the low-molecular liquid crystal is cross-linked and no longer exhibits liquid crystallinity. The optically anisotropic layer can be formed by applying a liquid crystal compound and, if necessary, a coating liquid containing a polymerizable initiator and optional components on the alignment film. A preferred example of the alignment film of the present invention is described in JP-A-8-338913.

(Bar-shaped liquid crystalline compound)
Examples of rod-like liquid crystalline compounds include azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines. , Phenyldioxanes, tolanes and alkenylcyclohexylbenzonitriles are preferably used.

  The rod-like liquid crystalline compound includes a metal complex. Moreover, the liquid crystal polymer which contains a rod-shaped liquid crystalline compound in a repeating unit can also be used as a rod-shaped liquid crystalline compound. That is, the rod-like liquid crystalline compound may be bonded to a (liquid crystal) polymer.

  As for rod-like liquid crystalline compounds, for example, Quarterly Chemical Review Vol. 22, Chapter 4 of Liquid Crystal Chemistry (1994), Chapter of Chemical Society of Japan, Chapter 7, Chapter 11 and Liquid Crystal Device Handbook Japan Society for the Promotion of Science, 142nd Committee The one described in Chapter 3 of the edition can be adopted.

  The birefringence of the rod-like liquid crystalline compound is preferably in the range of 0.001 to 0.7.

  The rod-like liquid crystalline compound preferably has a polymerizable group in order to fix its alignment state. The polymerizable group is preferably an unsaturated polymerizable group or an epoxy group, more preferably an unsaturated polymerizable group, and most preferably an ethylenically unsaturated polymerizable group.

(Discotic liquid crystalline compounds)
Examples of discotic liquid crystalline compounds include C.I. Benzene derivatives described in a research report of Destrade et al. (Mol. Cryst. 71, 111 (1981)), C.I. Destrode et al. (Mol. Cryst. 122, 141 (1985), Physics lett, A, 78, 82 (1990)) described in The cyclohexane derivatives described in the research report of Kohne et al. (Angew. Chem. 96, 70 (1984)) and M.M. Lehn et al. (JCS, Chem. Commun., 1794 (1985)), J.C. Azacrown-type and phenylacetylene-type macrocycles described in the research report of Zhang et al. (J. Am. Chem. Soc. 116, 2655 (1994)) are included.

  The discotic liquid crystalline compound also includes a compound having a structure in which a linear alkyl group, an alkoxy group, and a substituted benzoyloxy group are radially substituted as a side chain of the mother nucleus with respect to the mother nucleus at the center of the molecule. The molecule or the assembly of molecules is preferably a compound having rotational symmetry and imparting a certain orientation. The optically anisotropic layer formed from the discotic liquid crystalline compound does not necessarily require that the compound finally contained in the optically anisotropic layer is a discotic liquid crystalline compound. Also included are compounds having a group that reacts with heat or light and, as a result, polymerized or crosslinked by reaction with heat or light, resulting in a high molecular weight and loss of liquid crystallinity. Preferred examples of the discotic liquid crystalline compound are described in JP-A-8-50206. Moreover, about superposition | polymerization of a discotic liquid crystalline compound, Unexamined-Japanese-Patent No. 8-27284 has description.

  In order to fix the discotic liquid crystalline compound by polymerization, it is necessary to bond a polymerizable group as a substituent to the discotic core of the discotic liquid crystalline compound. However, when the polymerizable group is directly connected to the disc-shaped core, it becomes difficult to maintain the orientation state in the polymerization reaction. Therefore, a linking group is introduced between the discotic core and the polymerizable group. Therefore, the discotic liquid crystalline compound having a polymerizable group is preferably a compound represented by the following formula (5).

General formula (5)
D (-LQ) _r
In general formula (5), D is a discotic core, L is a divalent linking group, Q is a polymerizable group, and r is an integer of 4 to 12.

  An example of the disk-shaped core (D) is shown below. In each of the following examples, LQ (or QL) means a combination of a divalent linking group (L) and a polymerizable group (Q).

  In the general formula (5), the divalent linking group (L) is selected from the group consisting of an alkylene group, an alkenylene group, an arylene group, —CO—, —NH—, —O—, —S—, and combinations thereof. It is preferable that it is a bivalent coupling group. The divalent linking group (L) is a divalent group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, —CO—, —NH—, —O—, and —S— are combined. More preferably, it is a linking group. The divalent linking group (L) is most preferably a divalent linking group in which at least two divalent groups selected from the group consisting of an alkylene group, an arylene group, -CO- and -O- are combined. . The alkylene group preferably has 1 to 12 carbon atoms. The alkenylene group preferably has 2 to 12 carbon atoms. The number of carbon atoms in the arylene group is preferably 6-10.

  Examples of the divalent linking group (L) are shown below. The left side is bonded to the discotic core (D), and the right side is bonded to the polymerizable group (Q). AL represents an alkylene group or an alkenylene group, and AR represents an arylene group. The alkylene group, alkenylene group and arylene group may have a substituent (eg, an alkyl group).

L1: -AL-CO-O-AL-,
L2: -AL-CO-O-AL-O-,
L3: -AL-CO-O-AL-O-AL-,
L4: -AL-CO-O-AL-O-CO-,
L5: -CO-AR-O-AL-,
L6: -CO-AR-O-AL-O-,
L7: -CO-AR-O-AL-O-CO-,
L8: -CO-NH-AL-,
L9: -NH-AL-O-,
L10: -NH-AL-O-CO-,
L11: -O-AL-,
L12: -O-AL-O-,
L13: -O-AL-O-CO-,
L14: -O-AL-O-CO-NH-AL-,
L15: -O-AL-S-AL-,
L16: -O-CO-AL-AR-O-AL-O-CO-,
L17: -O-CO-AR-O-AL-CO-,
L18: -O-CO-AR-O-AL-O-CO-,
L19: -O-CO-AR-O-AL-O-AL-O-CO-,
L20: -O-CO-AR-O-AL-O-AL-O-AL-O-CO-,
L21: -S-AL-,
L22: -S-AL-O-,
L23: -S-AL-O-CO-,
L24: -S-AL-S-AL-,
L25: -S-AR-AL-.

  The polymerizable group (Q) of the general formula (5) is determined according to the type of polymerization reaction. Examples of the polymerizable group (Q) are shown below.

  The polymerizable group (Q) is preferably an unsaturated polymerizable group (Q1, Q2, Q3, Q7, Q8, Q15, Q16, Q17) or an epoxy group (Q6, Q18). More preferably, it is most preferably an ethylenically unsaturated polymerizable group (Q1, Q7, Q8, Q15, Q16, Q17). A specific value of r is determined according to the type of the disk-shaped core (D). In addition, although the combination of several L and Q may differ, it is preferable that it is the same.

  In the hybrid alignment, the angle between the major axis (disk surface) of the discotic liquid crystal compound and the surface of the support, that is, the tilt angle is in the direction of the depth of the optically anisotropic layer (that is, perpendicular to the transparent support). And increases or decreases with increasing distance from the plane of the polarizing film. The angle preferably increases with increasing distance. Further, the change in the tilt angle can be continuous increase, continuous decrease, intermittent increase, intermittent decrease, change including continuous increase and continuous decrease, or intermittent change including increase and decrease. . The intermittent change includes a region where the inclination angle does not change in the middle of the thickness direction. Even if a region where the angle does not change is included, it may be increased or decreased as a whole. However, it is preferred that the tilt angle changes continuously.

  The average direction of the major axis (disk surface) of the discotic liquid crystalline compound (average of the major axis direction of each molecule) is generally selected by selecting the discotic liquid crystalline compound or the material of the alignment film, or selecting the rubbing treatment method. By doing so, it can be adjusted. The major axis (disk surface) direction of the discotic liquid crystalline compound on the surface side (air side) is generally adjusted by selecting the type of additive used together with the discotic liquid crystalline compound or the discotic liquid crystalline compound. be able to.

  Examples of the additive used together with the discotic liquid crystalline compound include a plasticizer, a surfactant, a polymerizable monomer and a polymer. The degree of change in the orientation direction of the major axis can also be adjusted by selecting liquid crystalline molecules and additives as described above.

  The plasticizer, surfactant and polymerizable monomer used together with the discotic liquid crystalline compound are compatible with the discotic liquid crystalline compound, and can change the tilt angle of the discotic liquid crystalline compound or change the orientation. It is preferable not to inhibit. Among the additive components, addition of a polymerizable monomer (eg, a compound having a vinyl group, a vinyloxy group, an acryloyl group and a methacryloyl group) is preferable. The amount of the compound added is generally in the range of 1 to 50% by mass and preferably in the range of 5 to 30% by mass with respect to the discotic liquid crystalline compound. In addition, when a monomer having 4 or more polymerizable reactive functional groups is mixed and used, adhesion between the alignment film and the optically anisotropic layer can be improved.

  The optically anisotropic layer may contain a polymer together with the discotic liquid crystalline compound. The polymer preferably has a certain degree of compatibility with the discotic liquid crystalline compound and can change the tilt angle of the discotic liquid crystalline compound. A cellulose ester can be mentioned as an example of a polymer. Preferred examples of the cellulose ester include cellulose acetate, cellulose acetate propionate, hydroxypropyl cellulose, and cellulose acetate butyrate. The addition amount of the polymer is preferably in the range of 0.1 to 10% by mass with respect to the discotic liquid crystalline compound so as not to inhibit the orientation of the discotic liquid crystalline compound, and 0.1 to 8% by mass. More preferably, it is in the range of 0.1 to 5% by mass.

  The discotic nematic liquid crystal phase-solid phase transition temperature of the discotic liquid crystalline compound is preferably 70 to 300 ° C, more preferably 70 to 170 ° C.

(Fixing the alignment state of liquid crystalline molecules)
The aligned liquid crystal molecules can be fixed while maintaining the alignment state. The immobilization is preferably performed by a polymerization reaction. The polymerization reaction includes a thermal polymerization reaction using a thermal polymerization initiator and a photopolymerization reaction using a photopolymerization initiator. A photopolymerization reaction is preferred.

  Examples of photopolymerization initiators include α-carbonyl compounds (described in US Pat. Nos. 2,367,661 and 2,367,670), acyloin ethers (described in US Pat. No. 2,448,828), α-hydrocarbon substituted aromatic acyloin compounds ( U.S. Pat. No. 2,722,512), polynuclear quinone compounds (U.S. Pat. Phenazine compounds (described in JP-A-60-105667 and US Pat. No. 4,239,850) and oxadiazole compounds (described in US Pat. No. 4,221,970) are included.

  The amount of the photopolymerization initiator used is preferably in the range of 0.01 to 20% by mass, more preferably in the range of 0.5 to 5% by mass, based on the solid content of the coating solution.

  It is preferable to use ultraviolet rays for light irradiation for polymerization of liquid crystalline molecules.

The irradiation energy is preferably in the range of ^{20mJ / cm 2 ~50J / cm 2} , more preferably in the range of ^{20mJ / cm 2 ~5000mJ / cm 2} , a range of 100mJ / cm ² ~800mJ / cm ² More preferably. In order to accelerate the photopolymerization reaction, light irradiation may be performed under heating conditions.

  A protective layer may be provided on the optically anisotropic layer.

  The optically anisotropic layer is prepared by preparing a coating solution containing at least one of the liquid crystalline compounds and, optionally, an additive such as a polymerizable initiator and a fluorine-based polymer, and applying the coating solution to the alignment film surface. It can be formed by drying.

  Examples of the fluorine-based compound include conventionally known compounds. Specific examples include the fluorine-based compounds described in paragraphs [0028] to [0056] of JP-A-2001-330725. It is done.

  As the solvent used for preparing the coating solution, an organic solvent is preferably used. Examples of organic solvents include amides (eg, N, N-dimethylformamide), sulfoxides (eg, dimethyl sulfoxide), heterocyclic compounds (eg, pyridine), hydrocarbons (eg, benzene, hexane), alkyl halides (eg, , Chloroform, dichloromethane, tetrachloroethane), esters (eg, methyl acetate, butyl acetate), ketones (eg, acetone, methyl ethyl ketone), ethers (eg, tetrahydrofuran, 1,2-dimethoxyethane). Alkyl halides and ketones are preferred. Two or more organic solvents may be used in combination.

  When producing a highly uniform optical compensation film, the surface tension of the coating solution is preferably 25 mN / m or less, and more preferably 22 mN / m or less.

  The coating liquid can be applied by a known method (eg, extrusion coating method, direct gravure coating method, reverse gravure coating method, die coating method).

[Polarizer]
(Polarizing film)
The polarizing film that can be used in the polarizing plate of the present invention is preferably a coating-type polarizing film represented by Optiva, or a polarizing film composed of a binder and iodine or a dichroic dye.

  Iodine and dichroic dye in the polarizing film exhibit deflection performance by being oriented in the binder. It is preferable that the iodine and the dichroic dye are aligned along the binder molecule, or the dichroic dye is aligned in one direction by self-assembly such as liquid crystal.

  A general-purpose polarizer can be produced, for example, by immersing a stretched polymer in a solution of iodine or a dichroic dye in a bath and allowing the iodine or dichroic dye to penetrate into the binder. it can.

  In general-purpose polarizing films, iodine or dichroic dye is distributed about 4 μm (about 8 μm on both sides) from the polymer surface, and a thickness of at least 10 μm is necessary to obtain sufficient polarization performance. The penetrability can be controlled by the solution concentration of iodine or dichroic dye, the temperature of the bath, and the immersion time.

  As described above, the lower limit of the binder thickness is preferably 10 μm. On the other hand, the upper limit of the thickness is not particularly limited, but the thinner the better, from the viewpoint of the light leakage phenomenon that occurs when the polarizing plate is used in a liquid crystal display device. Currently, it is preferably a general-purpose polarizing plate (about 30 μm) or less, preferably 25 μm or less, and more preferably 20 μm or less. When it is 20 μm or less, the light leakage phenomenon is not observed in a 17-inch liquid crystal display device.

  The binder of the polarizing film may be cross-linked. As the crosslinked binder, a polymer that can be crosslinked by itself can be used. A polarizing film can be formed by reacting a polymer having a functional group or a binder obtained by introducing a functional group into a polymer between the binders by light, heat, or pH change.

  Moreover, you may introduce | transduce a crosslinked structure into a polymer with a crosslinking agent. It can be formed by cross-linking between binders by introducing a bonding group derived from the cross-linking agent between binders using a cross-linking agent which is a compound having high reaction activity.

  Crosslinking is generally carried out by applying a coating liquid containing a polymer or a mixture of a polymer and a crosslinking agent on a transparent support and then heating. Since it is only necessary to ensure durability at the stage of the final product, the cross-linking treatment may be performed at any stage until the final polarizing plate is obtained.

  As the binder for the polarizing film, either a polymer that can be crosslinked by itself or a polymer that is crosslinked by a crosslinking agent can be used. Examples of polymers include polymethyl methacrylate, polyacrylic acid, polymethacrylic acid, polystyrene, gelatin, polyvinyl alcohol, modified polyvinyl alcohol, poly (N-methylolacrylamide), polyvinyltoluene, chlorosulfonated polyethylene, nitrocellulose, chlorinated Polyolefin (eg, polyvinyl chloride), polyester, polyimide, polyvinyl acetate, polyethylene, carboxymethyl cellulose, polypropylene, polycarbonate and copolymers thereof (eg, acrylic acid / methacrylic acid polymer, styrene / maleimide polymer, styrene / vinyl) Toluene polymer, vinyl acetate / vinyl chloride polymer, ethylene / vinyl acetate polymer). Water-soluble polymers (eg, poly (N-methylolacrylamide), carboxymethylcellulose, gelatin, polyvinyl alcohol and modified polyvinyl alcohol) are preferred, gelatin, polyvinyl alcohol and modified polyvinyl alcohol are more preferred, and polyvinyl alcohol and modified polyvinyl alcohol are most preferred. .

  The saponification degree of polyvinyl alcohol and modified polyvinyl alcohol is preferably 70 to 100%, more preferably 80 to 100%, and most preferably 95 to 100%. As for the polymerization degree of polyvinyl alcohol, 100-5000 are preferable.

The modified polyvinyl alcohol is obtained by introducing a modifying group into polyvinyl alcohol by copolymerization modification, chain transfer modification or block polymerization modification. In the copolymerization modification, —COONa, —Si (OH) ₃ , N (CH ₃ ) ₃ .Cl, C ₉ H ₁₉ COO—, —SO ₃ Na, —C ₁₂ H ₂₅ may be introduced as modifying groups. it can. In chain transfer modification, —COONa, —SH, or —SC ₁₂ H ₂₅ can be introduced as a modifying group. The degree of polymerization of the modified polyvinyl alcohol is preferably 100 to 3000. The modified polyvinyl alcohol is described in JP-A-8-338913, JP-A-9-152509, and JP-A-9-316127.

  Unmodified polyvinyl alcohol and alkylthio-modified polyvinyl alcohol having a saponification degree of 85 to 95% are particularly preferable.

  Two or more kinds of polyvinyl alcohol and modified polyvinyl alcohol may be used in combination.

  If a large amount of the binder crosslinking agent is added, the heat and humidity resistance of the polarizing film can be improved. However, when a crosslinking agent is added in an amount of 50% by mass or more based on the binder, the orientation of iodine or the dichroic dye is lowered. 0.1-20 mass% is preferable with respect to a binder, and, as for the addition amount of a crosslinking agent, 0.5-15 mass% is more preferable.

  The binder contains some crosslinking agent that has not reacted even after the crosslinking reaction has been completed. However, the amount of the remaining crosslinking agent is preferably 1.0% by mass or less, and more preferably 0.5% by mass or less in the binder. If the binder layer contains a crosslinking agent in an amount exceeding 1.0% by mass, there may be a problem in durability. That is, when a polarizing film having a large amount of residual crosslinking agent is incorporated in a liquid crystal display device and used for a long time or left in a high-temperature and high-humidity atmosphere for a long time, the degree of polarization may decrease.

  The crosslinking agent is described in US Reissue Patent 23297. Boron compounds (eg, boric acid, borax) can also be used as a crosslinking agent.

  As the dichroic dye, an azo dye, stilbene dye, pyrazolone dye, triphenylmethane dye, quinoline dye, oxazine dye, thiazine dye or anthraquinone dye is used. The dichroic dye is preferably water-soluble. The dichroic dye preferably has a hydrophilic substituent (eg, sulfo, amino, hydroxyl).

  Examples of dichroic dyes include C.I. I. Direct Yellow 12, C.I. I. Direct Orange 39, C.I. I. Direct Orange 72, C.I. I. Direct Red 39, C.I. I. Direct Red 79, C.I. I. Direct Red 81, C.I. I. Direct Red 83, C.I. I. Direct Red 89, C.I. I. Direct Violet 48, C.I. I. Direct Blue 67, C.I. I. Direct Blue 90, C.I. I. Direct Green 59, C.I. I. Acid Red 37 is included. As for the dichroic dyes, those described in JP-A-1-161202, 1-172906, 1-172907, 1-183602, 1-248105, 1-265205, 7-261024 are used. There are descriptions in each publication. The dichroic dye is used as a free acid or an alkali metal salt, ammonium salt or amine salt. By blending two or more kinds of dichroic dyes, polarizing films having various hues can be produced. A polarizing film using a compound (pigment) that exhibits a black color when the polarization axes are orthogonal to each other, or a polarizing film or a polarizing plate in which various dichroic molecules are blended so as to exhibit a black color, both with a single plate transmittance and a polarization rate It is excellent and preferable.

  In order to increase the contrast ratio of the liquid crystal display device, the transmittance of the polarizing plate is preferably higher and the degree of polarization is preferably higher. The transmittance of the polarizing plate is preferably in the range of 30 to 50%, more preferably in the range of 35 to 50%, and in the range of 40 to 50% in the light having a wavelength of 550 nm (of the polarizing plate). Most preferably, the maximum value of the single plate transmittance is 50%. The degree of polarization is preferably in the range of 90 to 100%, more preferably in the range of 95 to 100%, and most preferably in the range of 99 to 100% in light having a wavelength of 550 nm.

  It is also possible to arrange the polarizing film and the optically anisotropic layer, or the polarizing film and the alignment film via an adhesive. As the adhesive, a polyvinyl alcohol resin (including a modified polyvinyl alcohol with an acetoacetyl group, a sulfonic acid group, a carboxyl group, or an oxyalkylene group) or an aqueous boron compound solution can be used. Of these, polyvinyl alcohol resins are preferred. The thickness of the adhesive layer is preferably in the range of 0.01 to 10 μm after drying, and particularly preferably in the range of 0.05 to 5 μm.

(Manufacture of polarizing plates)
From the viewpoint of yield, the polarizing film is stretched by tilting the binder at an angle of 10 to 80 degrees with respect to the longitudinal direction (MD direction) of the polarizing film (stretching method), or rubbed (rubbing method). It is preferable to dye with a dichroic dye. The tilt angle is preferably stretched so as to match the angle formed between the transmission axis of the two polarizing plates bonded to both sides of the liquid crystal cell constituting the LCD and the vertical or horizontal direction of the liquid crystal cell.

  A normal inclination angle is 45 degrees. Recently, however, devices that are not necessarily 45 degrees have been developed for transmissive, reflective, and transflective LCDs, and it is preferable that the stretching direction can be arbitrarily adjusted in accordance with the design of the LCD.

  In the stretching method, the stretching ratio is preferably 2.5 to 30.0 times, and more preferably 3.0 to 10.0 times. Stretching can be performed by dry stretching in air. Moreover, you may implement wet extending | stretching in the state immersed in water. The stretch ratio of dry stretching is preferably 2.5 to 5.0 times, and the stretch ratio of wet stretching is preferably 3.0 to 10.0 times. The stretching step may be performed in several steps including oblique stretching. By dividing into several times, it is possible to stretch more uniformly even at high magnification. Before the oblique stretching, a slight stretching (a degree to prevent shrinkage in the width direction) may be performed horizontally or vertically. Note that. The stretching ratio here is expressed by a ratio (L ′ / L) of a length (L) before stretching and a length (L ′) after stretching, with a mark on the film before stretching. The

  Stretching can be performed by performing tenter stretching in biaxial stretching in different steps. The biaxial stretching is the same as the stretching method performed in normal film formation. In biaxial stretching, stretching is performed at different speeds on the left and right, so the thickness of the binder film before stretching needs to be different on the left and right. In casting film formation, the flow rate of the binder solution can be differentiated between left and right by tapering the die.

  As described above, a binder film that is obliquely stretched by 10 to 80 degrees with respect to the MD direction of the polarizing film is manufactured.

  In the rubbing method, a rubbing treatment method widely adopted as a liquid crystal alignment treatment process of LCD can be applied. That is, orientation is obtained by rubbing the surface of the film in a certain direction using paper, gauze, felt, rubber, nylon, or polyester fiber. Generally, it is carried out by rubbing several times using a cloth in which fibers having a uniform length and thickness are planted on average. It is preferable to carry out using a rubbing roll in which the roundness, cylindricity, and deflection (eccentricity) of the roll itself are all 30 μm or less. The wrap angle of the film on the rubbing roll is preferably 0.1 to 90 degrees. However, as described in JP-A-8-160430, a stable rubbing treatment can be obtained by winding 360 degrees or more.

  When rubbing a long film, it is preferable to transport the film at a speed of 1 to 100 m / min with a constant tension by a transport device. The rubbing roll is preferably rotatable in the horizontal direction with respect to the film traveling direction for setting an arbitrary rubbing angle. It is preferable to select an appropriate rubbing angle in the range of 0 to 60 degrees. When used in a liquid crystal display device, 40 to 50 degrees is preferable. 45 degrees is particularly preferable.

[Liquid Crystal Display]
The optical compensation film and polarizing plate of the present invention can be used for liquid crystal display devices of various modes. Hereinafter, preferred forms of the optically anisotropic layer in each liquid crystal mode will be described.

(TN mode liquid crystal display)
The TN mode liquid crystal cell is most frequently used as a color TFT liquid crystal display device, and is described in many documents.

  The alignment state in the liquid crystal cell in the TN mode black display is an alignment state in which a rod-like liquid crystalline molecule rises at the center of the cell and the rod-like liquid crystalline compound lies in the vicinity of the cell substrate.

  The rod-like liquid crystalline compound in the center of the cell is compensated with a discotic liquid crystalline compound of the homeotropic orientation (horizontal orientation in which the disk surface is lying) or a (transparent) support, and the rod-like liquid crystalline property in the vicinity of the cell substrate The compound can be compensated with a discotic liquid crystalline compound having a hybrid alignment (an alignment in which the inclination of the major axis changes with the distance from the polarizing film).

  In addition, the rod-like liquid crystalline compound at the center of the cell is compensated with a rod-like liquid crystalline compound having a homogeneous orientation (horizontal orientation in which the major axis lies) or a (transparent) support, and the rod-like liquid crystalline property in the vicinity of the cell substrate is compensated. The compound can be compensated with a discotic liquid crystalline compound having a hybrid alignment.

  The homeotropic alignment liquid crystal compound is aligned in a state where the angle between the average alignment direction of the major axis of the liquid crystal compound and the plane of the polarizing film is 85 to 95 degrees.

  The liquid crystal compound of homogeneous alignment is aligned with the angle between the average alignment direction of the major axis of the liquid crystal compound and the plane of the polarizing film being less than 5 degrees.

  In the hybrid alignment liquid crystalline compound, the angle between the long axis average alignment direction of the liquid crystalline compound and the plane of the polarizing film is preferably 15 degrees or more, and more preferably 15 degrees to 85 degrees.

  (Transparent) Optically anisotropic layer in which the support or discotic liquid crystalline compound is homeotropically oriented, optically anisotropic layer in which rod-like liquid crystalline compound is homogeneously oriented, or even homeotropically oriented discotic The optically anisotropic layer composed of a mixture of a liquid crystal compound and a homogeneously aligned rod-like liquid crystal compound preferably has an Rth retardation value of 40 nm to 200 nm and an Re retardation value of 0 to 70 nm.

  Regarding the discotic liquid crystal compound layer having homeotropic alignment (horizontal alignment) and the rod-like liquid crystal compound layer having homogeneous alignment (horizontal alignment), Japanese Patent Laid-Open Nos. 12-304931 and 12-304932 describe them. Are listed. The discotic liquid crystal compound layer having a hybrid orientation is described in JP-A-8-50206.

(OCB mode liquid crystal display)
The OCB mode liquid crystal cell is a bend alignment mode liquid crystal cell in which a rod-like liquid crystal compound is aligned in a substantially opposite direction (symmetrically) between an upper portion and a lower portion of the liquid crystal cell. Liquid crystal display devices using a bend alignment mode liquid crystal cell are disclosed in US Pat. Nos. 4,583,825 and 5,410,422. Since the rod-like liquid crystal compounds are symmetrically aligned at the upper and lower portions of the liquid crystal cell, the bend alignment mode liquid crystal cell has a self-optical compensation function. Therefore, this liquid crystal mode is called an OCB (Optically Compensatory Bend) liquid crystal mode.

  Similarly to the TN mode, the liquid crystal cell in the OCB mode is in a black display, and the alignment state in the liquid crystal cell is such that the rod-like liquid crystal compound rises at the center of the cell and the rod-like liquid crystal compound lies in the vicinity of the cell substrate. .

  Since the TN mode and the alignment of the liquid crystal are the same in black display, the preferred mode is the same for the TN mode. However, since the OCB mode has a larger range in which the liquid crystal compound has risen at the center of the cell than the TN mode, an optically anisotropic layer in which the discotic liquid crystal compound is homeotropically aligned or a rod-like liquid crystal It is necessary to slightly adjust the retardation value of the optically anisotropic layer in which the functional compound is homogeneously oriented. Specifically, the optically anisotropic layer in which the discotic liquid crystalline compound on the (transparent) support is homeotropically aligned or the optically anisotropic layer in which the rod-like liquid crystalline compound is homogeneously aligned is Rth The retardation value is preferably 150 nm to 500 nm, and the Re retardation value is preferably 20 to 70 nm.

(VA mode liquid crystal display device)
In the VA mode liquid crystal cell, the rod-like liquid crystalline compound is aligned substantially vertically when no voltage is applied.

  The VA mode liquid crystal cell includes (1) a narrowly defined VA mode liquid crystal cell in which a rod-like liquid crystal compound is aligned substantially vertically when no voltage is applied, and is substantially horizontally aligned when a voltage is applied (Japanese Patent Laid-Open No. 2). 176625 (in Japanese Patent Publication No. 176625), and (2) a liquid crystal cell (SID97, Digest of tech. Papers (Proceedings) 28 (1997) 845 in which the VA mode is converted into a multi-domain (for MVA mode) in order to enlarge the viewing angle. ), (3) A liquid crystal cell in a mode (n-ASM mode) in which a rod-like liquid crystalline compound is substantially vertically aligned when no voltage is applied and twisted multi-domain alignment is applied when a voltage is applied (Preliminary Collection 58-59 of the Japan Liquid Crystal Society) (1998)) and (4) SURVAVAL mode liquid crystal cells (announced at LCD International 98).

  In the black display of the VA mode liquid crystal display device, most of the rod-like liquid crystalline compounds in the liquid crystal cell are in a standing state, so that the optically anisotropic layer in which the discotic liquid crystalline compounds are homeotropically aligned, Alternatively, the liquid crystalline compound is compensated by an optically anisotropic layer in which the rod-like liquid crystalline compound is homogeneously oriented, and separately, the rod-like liquid crystalline compound is homogeneously oriented, and the average orientation direction of the major axis of the rod-like liquid crystalline compound and the polarizing film It is preferable to compensate the viewing angle dependency of the polarizing plate with an optically anisotropic layer having an angle with respect to the transmission axis direction of less than 5 degrees.

  The optically anisotropic layer in which the discotic liquid crystalline compound is homeotropically aligned or the optically anisotropic layer in which the rod-like liquid crystalline compound is homogeneously aligned has an Rth retardation value of 150 nm to 500 nm, It is preferable that a foundation value is 20-70 nm.

(Other liquid crystal display devices)
The ECB mode and STN mode liquid crystal display devices can be optically compensated in the same way as described above.

(A) Application of antireflection layer (antireflection film)
An antireflection layer may be provided on the thermoplastic film of the present invention. The antireflection film generally includes a low refractive index layer which is also an antifouling layer, and at least one layer having a higher refractive index than that of the low refractive index layer (that is, a high refractive index layer and a medium refractive index layer) as a transparent substrate. It is provided above.

  Colloidal metal by multilayer deposition of transparent thin films of inorganic compounds (metal oxides, etc.) with different refractive indexes by chemical vapor deposition (CVD) method, physical vapor deposition (PVD) method, sol-gel method of metal compounds such as metal alkoxides Examples include a method of forming a thin film by post-processing (ultraviolet irradiation: JP-A-9-157855, plasma processing: JP-A-2002-327310) after forming an oxide particle film.

  On the other hand, various antireflection films formed by laminating thin films in which inorganic particles are dispersed in a matrix have been proposed as antireflection films with high productivity.

  The antireflection film which consists of the antireflection film which gave the anti-glare property which the surface of the uppermost layer gave the anti-glare property to the antireflection film by application | coating as mentioned above was mentioned.

  The thermoplastic film of the present invention can be applied to any of the above methods, but the coating method (coating type) is particularly preferable.

(A-1) Layer structure of coating type antireflection film An antireflection film having a layer structure in the order of at least a medium refractive index layer, a high refractive index layer, and a low refractive index layer (outermost layer) on the substrate has the following relationship: It is designed to have a refractive index that satisfies

The refractive index of the high refractive index layer> The refractive index of the medium refractive index layer> The refractive index of the transparent support> The refractive index of the low refractive index layer Further, a hard coat layer is provided between the transparent support and the medium refractive index layer. May be. Furthermore, it may consist of a medium refractive index hard coat layer, a high refractive index layer and a low refractive index layer.

  Examples thereof include JP-A-8-122504, JP-A-8-110401, JP-A-10-300902, JP-A-2002-243906, JP-A-2000-11706, and the like.

  Other functions may be imparted to each layer, for example, an antifouling low refractive index layer or an antistatic high refractive index layer (for example, JP-A-10-206603, JP-A-2002). -243906 publication etc.) etc. are mentioned.

  The haze of the antireflection film is preferably 5% or less, more preferably 3% or less. Further, the strength of the film is preferably H or more, more preferably 2H or more, and most preferably 3H or more in a pencil hardness test according to JIS K5400.

(A-2) High Refractive Index Layer and Medium Refractive Index Layer A layer having a high refractive index of the antireflective film includes at least a high refractive index inorganic compound ultrafine particle having an average particle size of 100 nm or less and a matrix binder. Consists of.

  Examples of the high refractive index inorganic compound fine particles include inorganic compounds having a refractive index of 1.65 or more, preferably those having a refractive index of 1.9 or more. Examples thereof include oxides such as Ti, Zn, Sb, Sn, Zr, Ce, Ta, La, and In, and composite oxides containing these metal atoms.

  In order to obtain such ultrafine particles, the surface of the particles is treated with a surface treatment agent (for example, silane coupling agents, etc .: JP-A-11-295503, JP-A-11-153703, JP-A-2000-9908). No., anionic compound or organometallic coupling agent: Japanese Patent Laid-Open No. 2001-310432, etc., core-shell structure with high refractive index particles as a core (Japanese Patent Laid-Open No. 2001-166104, etc.), specific dispersant Combined use (Japanese Patent Laid-Open No. 11-153703, US Pat. No. 6,210,858, Japanese Patent Laid-open No. 2002-27776069, etc.)

  Examples of the material forming the matrix include conventionally known thermoplastic resins and curable resin films.

  Furthermore, it is selected from a polyfunctional compound-containing composition containing at least two radically polymerizable and / or cationically polymerizable groups, an organometallic compound containing a hydrolyzable group, and a partial condensate composition thereof. At least one composition is preferred. Examples thereof include compounds described in JP-A Nos. 2000-47004, 2001-315242, 2001-31871, and 2001-296401.

  A curable film obtained from a colloidal metal oxide obtained from a hydrolyzed condensate of metal alkoxide and a metal alkoxide composition is also preferred. For example, it describes in Unexamined-Japanese-Patent No. 2001-293818.

  The refractive index of the high refractive index layer is generally 1.70 to 2.20. The thickness of the high refractive index layer is preferably 5 nm to 10 μm, and more preferably 10 nm to 1 μm.

  The refractive index of the middle refractive index layer is adjusted to be a value between the refractive index of the low refractive index layer and the refractive index of the high refractive index layer. The refractive index of the middle refractive index layer is preferably 1.50 to 1.70.

(A-3) Low Refractive Index Layer The low refractive index layer is formed by sequentially laminating on the high refractive index layer. The refractive index of the low refractive index layer is 1.20 to 1.55. Preferably it is 1.30-1.50.

  It is preferable to construct as the outermost layer having scratch resistance and antifouling property. As means for greatly improving the scratch resistance, imparting slipperiness to the surface is effective, and conventionally known thin film layer means such as introduction of silicone or introduction of fluorine can be applied.

  The refractive index of the fluorine-containing compound is preferably 1.35 to 1.50. More preferably, it is 1.36-1.47. The fluorine-containing compound is preferably a compound containing a crosslinkable or polymerizable functional group containing fluorine atoms in the range of 35 to 80% by mass.

  For example, paragraph numbers [0018] to [0026] of Japanese Patent Application Laid-Open No. 9-222503, paragraph numbers [0019] to [0030] of Japanese Patent Application Laid-Open No. 11-38202, and paragraph numbers of Japanese Patent Application Laid-Open No. 2001-40284. [0027] to [0028], JP-A 2000-284102, and the like.

  The silicone compound is a compound having a polysiloxane structure, preferably containing a curable functional group or a polymerizable functional group in the polymer chain and having a crosslinked structure in the film. For example, reactive silicone (eg, Silaplane (manufactured by Chisso Corporation), silanol group-containing polysiloxane (Japanese Patent Laid-Open No. 11-258403, etc.) at both ends, etc.) can be mentioned.

  The crosslinking or polymerization reaction of the fluorine-containing and / or siloxane polymer having a crosslinking or polymerizable group is performed simultaneously with or after the application of the coating composition for forming the outermost layer containing a polymerization initiator, a sensitizer and the like. It is preferable to carry out by light irradiation or heating.

  Also preferred is a sol-gel cured film in which an organometallic compound such as a silane coupling agent and a specific fluorine-containing hydrocarbon group-containing silane coupling agent are cured by a condensation reaction in the presence of a catalyst.

  For example, a polyfluoroalkyl group-containing silane compound or a partially hydrolyzed condensate thereof (Japanese Patent Laid-Open Nos. 58-142958, 58-147483, 58-147484, Japanese Patent Laid-Open Nos. 9-157582, 11) -106704), silyl compounds containing a poly "perfluoroalkyl ether" group which is a fluorine-containing long chain group (Japanese Patent Application Laid-Open Nos. 2000-117902, 2001-48590, 2002) 53804), and the like.

  The low refractive index layer has an average primary particle diameter of 1 to 150 nm such as a filler (for example, silicon dioxide (silica), fluorine-containing particles (magnesium fluoride, calcium fluoride, barium fluoride)) as an additive other than the above. Low refractive index inorganic compounds, organic fine particles described in paragraphs [0020] to [0038] of JP-A-11-3820, etc.), silane coupling agents, slip agents, surfactants, and the like can be contained.

  When the low refractive index layer is located below the outermost layer, the low refractive index layer may be formed by a vapor phase method (vacuum deposition method, sputtering method, ion plating method, plasma CVD method, etc.). The coating method is preferable because it can be manufactured at a low cost.

  The film thickness of the low refractive index layer is preferably 30 to 200 nm, more preferably 50 to 150 nm, and most preferably 60 to 120 nm.

(A-4) Hard coat layer The hard coat layer is provided on the surface of the transparent support in order to impart physical strength to the antireflection film. In particular, it is preferably provided between the transparent support and the high refractive index layer.

  The hard coat layer is preferably formed by a crosslinking reaction or a polymerization reaction of a light and / or heat curable compound.

  The curable functional group is preferably a photopolymerizable functional group, and the hydrolyzable functional group-containing organometallic compound is preferably an organic alkoxysilyl compound.

  Specific examples of these compounds are the same as those exemplified for the high refractive index layer.

  Specific examples of the composition of the hard coat layer include those described in JP-A Nos. 2002-144913, 2000-9908, and WO 00/46617.

  The high refractive index layer can also serve as a hard coat layer. In such a case, it is preferable to form fine particles dispersed in the hard coat layer using the method described for the high refractive index layer.

  The hard coat layer can also serve as an antiglare layer (described later) provided with particles having an average particle size of 0.2 to 10 μm to provide an antiglare function (antiglare function).

  The film thickness of the hard coat layer can be appropriately designed depending on the application. The film thickness of the hard coat layer is preferably 0.2 to 10 μm, more preferably 0.5 to 7 μm.

  The strength of the hard coat layer is preferably H or higher, more preferably 2H or higher, and most preferably 3H or higher in a pencil hardness test according to JIS K5400. Further, in the Taber test according to JIS K5400, the smaller the wear amount of the test piece before and after the test, the better.

(A-5) Forward scattering layer The forward scattering layer is provided in order to give a viewing angle improvement effect when the viewing angle is inclined in the vertical and horizontal directions when applied to a liquid crystal display device. By dispersing fine particles having different refractive indexes in the hard coat layer, it can also serve as a hard coat function.

  For example, Japanese Patent Laid-Open No. 11-38208 specifying a forward scattering coefficient, Japanese Patent Laid-Open No. 2000-199809 having a relative refractive index of a transparent resin and fine particles in a specific range, and Japanese Patent Laid-Open No. 2002 specifying a haze value of 40% or more. -107512 gazette etc. are mentioned.

(A-6) Other layers In addition to the above layers, a primer layer, an antistatic layer, an undercoat layer, a protective layer, and the like may be provided.

(A-7) Coating method Each layer of the antireflection film is formed by a dip coating method, an air knife coating method, a curtain coating method, a roller coating method, a wire bar coating method, a gravure coating, a micro gravure method or an extrusion coating method (US patent). No. 2,681,294) can be formed by coating.

(A-8) Antiglare Function The antireflection film may have an antiglare function that scatters external light. The antiglare function is obtained by forming irregularities on the surface of the antireflection film. When the antireflection film has an antiglare function, the haze of the antireflection film is preferably 3 to 30%, more preferably 5 to 20%, and most preferably 7 to 20%.

  As a method for forming irregularities on the surface of the antireflection film, any method can be applied as long as these surface shapes can be sufficiently maintained. For example, a method of forming irregularities on the film surface by using fine particles in the low refractive index layer (for example, JP 2000-271878 A), a lower refractive index layer (high refractive index layer, medium refractive index layer or A relatively large particle (particle size 0.05 to 2 μm) is added to the hard coat layer) in small amounts (0.1 to 50% by mass) to form a surface uneven film, and these shapes are maintained on the surface to reduce the thickness. A method of providing a refractive index layer (for example, JP 2000-281410 A, JP 2000-95893 A, JP 2001-100004 A, 2001-281407, etc.), and a top layer (antifouling layer) are applied. A method of physically transferring an uneven shape to the surface after installation (for example, as an embossing method, JP-A-63-278839, JP-A-11-183710, JP-A-2000-275401, etc. ), And the like.

[Measurement method]
The measurement method used in the present invention is described below.

(1) Range of Rth / Re ratio and Rth / Re ratio (a) After slitting 5 cm at both ends of the film, 20 points were sampled at regular intervals over the entire width (3 cm × 3 cm square). At this time, each side of the square was cut out parallel to MD (film forming direction) and TD (width direction).

(B) After conditioning the sample film to 25 ° C. and 60% relative humidity for 5 hours or more, using an automatic birefringence meter (KOBRA-21ADH: manufactured by Oji Scientific Instruments) at 25 ° C. and 60% relative humidity As described above, the retardation value at a wavelength of 550 nm was measured from the direction perpendicular to the surface of the sample film and by 10 ° from the normal to the film surface by ± 10 °.

(C) In-plane retardation (Re) from the vertical (normal) direction, and retardation (Rth) in the thickness direction were calculated from measured values in the vertical direction and ± 10 to 50 ° direction.

(D) The average value of the Rth / Re ratio at each of these measurement points was defined as “Re / Rth ratio”. The difference between the maximum value and the minimum value among the 20 Rth / Re ratios was defined as the “Rth / Re ratio range”.

(2) Thermal dimensional change, thermal dimensional change unevenness (a) The following sample is sampled at a point obtained by dividing the entire width into five equal parts.
i) MD sample: MD15cm × TD5cm
ii) TD sample: TD15cm × MD5cm

(B) Each sample is conditioned for 3 hours or more at 25 ° C. and 60% rh, and measured in this environment using a 10 cm base length pin gauge. This is L1.

(C) Each sample is allowed to stand at 80 ° C. dry for 200 hours, then conditioned at 25 ° C. and 60% rh for 3 hours or longer, and measured in this environment using a 10 cm base length pin gauge. This is L2.

(D) The thermal dimensional change of each point (10 points) of MD and TD is measured from the following formula, and this average value is defined as the thermal dimensional change.
Thermal dimensional change (%) = 100 × | L2-L1 | / L1

(E) The difference between the maximum value and the minimum value of the thermal dimensional change (absolute value) among the 10 points was divided by the average value of the thermal dimensional change at 10 points, and the thermal dimensional change was uneven.

(3) Surface roughness Ra was measured using a compact laser interferometer (F601 manufactured by Fujinon Co., Ltd.).

(4) Glass transition temperature (Tg)
20 mg of the sample was placed in a measurement pan of a scanning differential calorimeter (DSC). This was heated from 30 ° C. to 250 ° C. at 10 ° C./min in a nitrogen stream (1st-run), and then cooled to 30 ° C. at −10 ° C./min. Thereafter, the temperature was raised again from 30 ° C. to 250 ° C. (2nd-run). The glass transition temperature (Tg) was defined as the temperature at which the baseline began to deviate from the low temperature side at 2nd-run.

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

1. Preparation of Unstretched Film (1) Cellulose Acylate Film (a) Melt Film-Forming Film A cellulose acetate propionate film (thickness 100 μm) of Example 1 of JP-A-2007-989817 was prepared. This was film #CM. This Tg was 146 ° C.

  A cellulose acylate film (thickness = 100 μm, Tg = 131 ° C.) was prepared according to Example 101 of Example B of JP-A No. 2007-169588. This was designated as film #CN.

(B) Solution casting film No. 1 described in Example 1 of JP-A-2001-188128. 1 (cellulose acetate propionate: thickness 100 μm) was prepared. This was designated as film #CS. This Tg was 150 ° C.

(2) Cycloolefin film (a) Melt film-forming film Melt film-forming was carried out using the following resins.

Resin A: Polyplastics Co., Ltd. TOPAS6013 (Tg = 130 ° C.)
Resin B: APEL6015T (Tg = 145 ° C.) manufactured by Mitsui Chemicals, Inc.
Resin C: Compound of Example 1 of WO 98/14499 (Tg = 136 ° C.)
Resin D: “Resin A-1” (Tg = 165 ° C.) described in Synthesis Example 1 in Examples of JP2007-108529A
Resin E: APEL 6013T (Tg = 125 ° C.) manufactured by Mitsui Chemicals, Inc.

  These were dried in a vacuum dryer at 110 ° C. to a water content of 0.1% or less, melted at 260 ° C. using a single-screw kneading extruder, sent out from a gear pump, and then filtered with a leaf disk filter having a filtration accuracy of 5 μm. Filter and melt from a hanger coat die with a slit spacing of 0.8 mm and 270 ° C. via a static mixer onto a triple cast roll set to (Tg-5) ° C., Tg ° C. and (Tg-10) ° C. (Molten resin) was extruded. At this time, the touch roll was brought into contact with the most upstream cast roll at the following surface pressure to form an unstretched film having a thickness of 100 μm. The touch roll was the one described in Example 1 of JP-A-11-235747 (the one described as a double holding roll), and the temperature was adjusted to Tg-5 ° C. (however, the thickness of the thin metal outer cylinder was 2 mm) did).

  Then, after trimming both ends (each 3% of the total width) just before winding, the both ends were subjected to thicknessing (knurling) with a width of 10 mm and a height of 20 μm. In each level, the width was 1.5 m, and 3000 m was wound at 30 m / min.

Resin touch roll pressure Film # OM1 Resin A (addition polymerization system) 0 MPa (without touch roll)
Film # OM2 Resin A (addition polymerization system) 0.1 MPa
Film # OM3 Resin A (addition polymerization system) 1 MPa
Film # OM4 Resin A (addition polymerization system) 4.5 MPa
Film # OM5 Resin A (addition polymerization system) 6 MPa
Film # OM6 Resin B (addition polymerization system) 1 MPa
Film # OM7 Resin C (ring-opening polymerization system) 1 MPa
Film # OM8 Resin D (ring-opening polymerization system) 1 MPa
Film # OM9 Resin E (addition polymerization system) 1 MPa

(B) Solution film-forming film A film #OS having a thickness of 100 μm was prepared according to the production example described in JP-A-2007-108529. This uses the same resin as the film # OM8 and has a Tg of 165 ° C.

2. Transverse stretch / longitudinal shrinkage The unstretched film was stretched tenterly in the transverse direction at Tg + 5 at the magnifications shown in Tables 1 and 2. Thereafter, longitudinal shrinkage was performed by the method described in Table 1. The longitudinal shrinkage was performed in a heat treatment zone in which 10 rolls having a diameter of 40 cm were arranged so as to have G / D described in Tables 1 and 2. Further, for some levels, longitudinal stretching was performed at a stretching ratio shown in Tables 1 and 2 at Tg + 10 ° C. before transverse stretching. In the table, the longitudinal stretching ratio = 1 means that longitudinal stretching is not performed.

  The thermoplastic film thus transversely stretched and contracted in the longitudinal direction is subjected to the Re (average value of 20 points), Rth / Re ratio, Re / Rth ratio range, surface roughness, thermal dimensional change, thermal dimension by the above method. Unevenness of change and scratches were measured and listed in Tables 1 and 2. The scratches were visually inspected 100 m and evaluated for strength.

  In the case of carrying out the present invention, the orientation angles measured in the same manner as in Example 1 of JP-A-2007-108529 were all 90 ± 1 °, and the slow axis was TD oriented.

  In Table 1, the measurement value at 80 ° C. and 200 hours was described as the thermal dimensional change rate as described above, but the heat treatment was carried out by extending the time to 500 hours.

  In Examples 1-27 to 28 in Table 1, the film was fixed on the roll during the longitudinal shrinkage treatment under the same conditions as in Example 1-2. In Example 1-27, both ends (5% of each total width) were electrostatically applied (edge pinning) to fix the film. For this purpose, an electrostatic edge pinning device (DC stabilized power supply PSE-2005N and electrode HDE-20R-54) manufactured by Kasuga Electric was used, and the pinning voltage was -10 kV. In Example 1-28, the entire width of the film was fixed by using a roll as a suction drum. In Example 1-29, Y / X nip rolls (roll diameter = X) of 1/10 of the roll diameter were installed on the roll with respect to the length (lap length = Y) in contact with the roll. The nip rolls had a length of 5% of the total width and were installed at both ends.

3. Surface treatment (1) Cellulose acylate film After being immersed in a 2.0N potassium hydroxide solution (25 ° C.) for 2 minutes, the solution was neutralized with sulfuric acid, washed with pure water and dried. The surface energy of this PK-1 was determined by the contact angle method, and all were 60 to 65 mN / m.

(2) Film other than cellulose acylate film Corona discharge treatment was performed under the following conditions.
Electrode: Coron-Plus manufactured by VETAPONE
Generator: CP1C
Output: 900W
Film transport speed: 6m / min

4). Preparation of alignment film for optically anisotropic layer On these thermoplastic films, a coating solution having the following composition was applied at 28 mL / m ² with a # 16 wire bar coater. Drying was performed with warm air of 60 ° C. for 60 seconds, and further with warm air of 90 ° C. for 150 seconds.

(1) Alignment film coating solution composition Modified polyvinyl alcohol 20 parts by mass Water 360 parts by mass Methanol 120 parts by mass Glutaraldehyde (crosslinking agent) 1.0 part by mass

(2) Production of optically anisotropic layer On the alignment film, the following coating solution was conveyed at 30 m / min by rotating the wire bar # 3.2 in the same direction as the film conveying direction at 1171 rotations. It was continuously applied to the alignment film surface of the roll film. In the process of continuously heating from room temperature to 100 ° C., the solvent is dried, and then the film surface wind speed corresponding to the discotic liquid crystal compound layer is 1.5 m / sec parallel to the film transport direction in the 135 ° C. drying zone. And heated for about 90 seconds to align the discotic liquid crystal compound. Next, the film is transported to a drying zone at 80 ° C., and an ultraviolet ray with an illuminance of 600 mW is applied by an ultraviolet irradiation device (ultraviolet lamp: output 160 W / cm, emission length 1.6 m) with the surface temperature of the film being about 100 ° C. Irradiation was carried out for 4 seconds to advance the crosslinking reaction, and the discotic liquid crystal compound was fixed to the orientation. Then, it was allowed to cool to room temperature and wound into a cylindrical shape to form a roll. The thickness of the optically anisotropic layer was 1.3 μm.

  Further, the elastic modulus of the obtained optical compensation sheet was measured and found to be 2.4 MPa.

(Coating solution composition of optically anisotropic layer)
The following composition was dissolved in 97 parts by mass of methyl ethyl ketone to prepare a coating solution.

Discotic liquid crystal compound (1) having the following chemical formula 41.01 parts by mass Ethylene oxide modified trimethylolpropane triacrylate (V # 360, manufactured by Osaka Organic Chemical Co., Ltd.) 4.06 parts by mass Cellulose acetate butyrate (CAB551-0) 0.2, manufactured by Eastman Chemical Co., Ltd.) 0.34 parts by mass Cellulose acetate butyrate (CAB531-1, manufactured by Eastman Chemical Co., Ltd.) 0.11 parts by mass Fluoro aliphatic group-containing polymer 1 having the following chemical formula 0.56 parts by mass Fluoroaliphatic group-containing polymer 2 of chemical formula 0.06 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) 1.35 parts by mass Sensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) 0.45 Mass part discotic liquid crystalline compound (1)

  When the polarizing plate was placed in a crossed Nicol arrangement and the unevenness of the obtained optical compensation sheet was observed, the unevenness was not detected even when viewed from the front and the direction inclined to 60 degrees from the normal.

(3) Production of Polarizing Plate A polyvinyl alcohol (PVA) film having a thickness of 80 μm is dyed by immersing it in an iodine aqueous solution having an iodine concentration of 0.05 mass% at 30 ° C. for 60 seconds, and then boric acid concentration is 4 mass%. While being immersed in an aqueous boric acid solution for 60 seconds, the film was longitudinally stretched 5 times the original length and then dried at 50 ° C. for 4 minutes to obtain a polarizing film having a thickness of 20 μm.

  The optical compensation sheet was immersed in an aqueous sodium hydroxide solution at 55 ° C. at 1.5 mol / L, and then the sodium hydroxide was sufficiently washed away with water. Then, after being immersed in a diluted sulfuric acid aqueous solution at 35 ° C. for 1 minute at 0.005 mol / L, the diluted sulfuric acid aqueous solution was sufficiently washed away by immersion in water. Finally, the sample was thoroughly dried at 120 ° C.

  The optical compensation sheet subjected to the saponification treatment as described above was combined with a commercially available cellulose acylate film that was also subjected to the saponification treatment, and a polarizing plate was laminated using a polyvinyl alcohol adhesive so as to sandwich the polarizing film. Obtained. Here, as a commercially available cellulose acylate film, Fujitac TF80UL (manufactured by FUJIFILM Corporation) was used. At this time, since the polarizing film and the protective films on both sides of the polarizing film are produced in a roll form, the longitudinal directions of the roll films are parallel to each other and are continuously bonded. Therefore, the longitudinal direction of the optical compensation sheet roll (the casting direction of the cellulose acylate film) and the polarizer absorption axis were parallel to each other.

5). Evaluation with TN liquid crystal panel A pair of polarizing plates provided in a liquid crystal display device (MDT-191S, manufactured by Mitsubishi Electric Corporation) using a TN type liquid crystal panel is peeled off, and the above-prepared polarizing plate is used instead. The optical compensation sheets were attached to the viewer side and the backlight side one by one through an adhesive so that the optical compensation sheet was on the liquid crystal cell side. The transmission axis of the polarizing plate on the viewer side and the transmission axis of the polarizing plate on the backlight side were arranged to be in the O mode. The TN liquid crystal panel thus prepared was subjected to thermo treatment at 80 ° C. for 200 hours. After the thermo, the temperature was adjusted to 25 ° C. and 60% rh for 8 hours, and after humidity adjustment, the following evaluation was performed on the liquid crystal display device.

(A) Contrast and contrast unevenness Under normal indoor fluorescent lamp illumination, the transmission luminance from the lower side of the liquid crystal display device was measured using a spectral radiance meter. At this time, with the liquid crystal display device placed horizontally, the polar angle is fixed every 10 ° in the direction of 0 to 80 ° from the normal line, and the azimuth angle of the liquid crystal display device is changed every 10 ° at each angle. The brightness was measured while the liquid crystal display device was on and off, and the contrast ratio, which is the ratio of the brightness when the liquid crystal display device was on and off, was calculated. The values obtained by adding the contrast ratios in all polar angles and azimuths in all directions were scored and listed in Tables 1 and 2 as contrast. Further, this measurement was performed at the point where the entire screen was divided into 100 equal parts, and the unevenness of contrast was evaluated by dividing the difference between the maximum value and the minimum value by the average value and indicating the percentage.

(B) Light Leakage The liquid crystal display device was displayed in black, and a range where light leakage could be visually confirmed was obtained. This area was expressed as a percentage of the total area of the display screen.

(C) Evaluation result In Table 1, the examination result of process conditions, such as a vertical contraction process, was shown.

  The present invention 1-1 to 1-7 and Comparative Examples 1-1 to 1-2 showed the effect of G / D ratio in longitudinal shrinkage, but Comparative Example 1-1 below the scope of the present invention is Rth / Re. The range of the ratio increased and the contrast unevenness increased. Moreover, the thermal dimensional change increased and the light leakage increased. On the other hand, when the G / D ratio exceeded the range of the present invention, the Rth / Re ratio increased and the contrast decreased as in Comparative Example 1-2. On the other hand, those having a G / D ratio within the range of the present invention showed good characteristics.

  Inventions 1-8 to 1-10, Inventions 1-23 and 1-24, and Comparative Examples 1-3 and 1-4 showed the effect of V2 / V1. When V2 / V1 exceeded the range of the present invention, the Rth / Re ratio increased and the contrast decreased as shown in Comparative Example 1-3. When V2 / V1 was below the range of the present invention, the thermal dimensional change became too small, light leakage increased, and scratches during the vertical shrinkage treatment also increased. On the other hand, when V2 / V1 was within the range of the present invention, good characteristics were exhibited.

  Inventions 1-11 to 1-14 showed the effect of longitudinal shrinkage temperature. (Tg−20) ° C. to (Tg + 50) ° C. is preferable. When this range is exceeded, the Rth / Re ratio tends to increase and the contrast tends to decrease. Below the above temperature range, Rth / Re could not be lowered, the thermal dimensional change was likely to increase, and the contrast and the light leakage tended to decrease. On the other hand, those having a longitudinal shrinkage treatment temperature within the range of the present invention showed good characteristics.

  Inventions 1-15 to 1-19 show the results of changing the surface roughness by changing the touch roll conditions. When the surface roughness was too small, the squeeze with the roll was too strong, and scratches were generated as shown in the present invention 1-19. When the surface roughness was large, the range of Rth / Re ratio and Rth / Re ratio increased as shown in Invention 1-15, and the contrast was slightly lowered and the contrast unevenness was slightly increased. On the other hand, those having a surface roughness of 0.0005-0.004 showed good characteristics.

  The effect of the draw ratio was shown in the present invention 1-20 to 1-22. In the preferred range of the present invention (1.1 times or more and 3.0 times or less), good performance was exhibited, but in the present invention 1-22 stretched by 3.1 times, the Rth / Re ratio and the thermal dimensional change increased. Contrast unevenness and light leakage increased slightly.

  Inventions 1-2, 1-27, 1-28, and 1-29 showed the effect of fixing both ends during longitudinal contraction. Compared with the present invention 1-2 in which both ends are not fixed, the present invention 1-27, 1-28, and 1-29 (both edge pinning method, suction drum method, and nip roll method) in which both ends are fixed are liquid crystal display characteristics (contrast) Unevenness, light leakage) was improved.

  Table 2 shows the effects of film types.

  Compare film materials between melt casting methods. The addition-polymerized cycloolefins of the present invention 2-3, 2-4, and 2-13 were particularly excellent in that the Re expression was high, the range of the Rth / Re ratio was low, contrast unevenness and light leakage were small.

  Next, the ring-opening polymerization type cycloolefin shown in the present inventions 2-5 and 2-6 was superior. As compared with the addition polymerization system (Invention 2-3, 2-4), the range of Rth / Re ratio and the thermal dimensional change increased, the contrast unevenness, and the light leakage slightly increased.

  In the cellulose acylates of the present invention 2-1, 2-2, 2-12, Re is less likely to be expressed compared to cycloolefins of addition and ring-opening polymerization, and the range of Rth / Re ratio and thermal dimensional change increase. Contrast decreased slightly, contrast unevenness, and light leakage increased slightly.

  Examples of carrying out the present invention using a lactone ring-containing polymer and a polycarbonate polymer are shown in the present invention 2-8 to 2-10. Polycarbonate was prepared according to Example 1 of JP-A-2006-277914 and Example 1 of JP-A-2006-284703 (however, the latter did not perform longitudinal stretching but prepared an unstretched film). The lactone ring-containing polymer was formed into a film according to Example 1 described in International Publication No. 2006/025445. However, the film width was 1.5 m. The thicknesses of these original fabrics (unstretched films) were all prepared at 100 μm. Although good characteristics were also obtained, good results were obtained in the order of Inventions 2-10, 2-8, and 2-9.

  The present inventions 2-1 and 2-2 (cellulose acylate) and the present inventions 2-6 and 2-7 (cycloolefin) are compared in terms of the film forming method. In the method, the range of the Rth / Re ratio and the thermal dimensional change were slightly reduced, and the contrast unevenness and the light leakage were slightly reduced.

  In the present invention 2-7 and Comparative Example 2-1, the same film was subjected to longitudinal shrinkage of the present invention and the method of Example 1 described in JP-A-2007-108529 (using a simultaneous biaxial stretching machine) Comparison of longitudinal shrinkage in the tenter at the same time as transverse stretching. Invention 2-7 can reduce the range of Rth / Re ratio and thermal dimensional change, and as a result, can significantly reduce contrast unevenness and light leakage.

  In Comparative Example 2-2, ZEONOR (Tg = 136 ° C.) was longitudinally contracted simultaneously with transverse stretching in accordance with Example 1 described in JP-A-2006-133720. On the other hand, the present invention 2-11 is the same as the comparative example 2-2 in the transverse stretch ratio and the longitudinal shrinkage after the transverse stretching as in the present invention and then longitudinally shrunk on the roll according to the conditions (G / D) of the present invention. is there. The present invention 2-8 can reduce the Rth / Re ratio range and thermal dimensional change, and as a result, can significantly reduce contrast unevenness and light leakage.

6). Other Preparation of Liquid Crystal Display Element The polarizing plate of the present invention was prepared by using the liquid crystal display device described in Example 1 of JP-A-10-48420 and the discotic liquid crystal molecule described in Example 1 of JP-A-9-26572. Including an optically anisotropic layer, an alignment film coated with polyvinyl alcohol, a 20-inch VA liquid crystal display device described in FIGS. 2 to 9 of JP-A-2000-154261, and FIGS. 10 to 10 of JP-A-2000-154261. The 20-inch OCB type liquid crystal display device described in No. 15 and the IPS type liquid crystal display device shown in FIG. 11 of JP-A-2004-12731 were used. Furthermore, when the low reflection film of the present invention was applied to the outermost layer of these liquid crystal display devices and evaluated, a good liquid crystal display element was obtained.

7). Production of low-reflection film A low-reflection film was produced from the stretched thermoplastic film of the present invention according to Example 47 of the Japan Institute of Invention and Technology (Publication No. 2001-1745), and good optical performance was obtained.

It is a schematic block diagram which shows the film manufacturing apparatus which manufactures the thermoplastic film which concerns on this Embodiment. It is a perspective view which shows the arrangement | positioning state of the some roll in a heat processing zone. It is explanatory drawing which shows the roll wrap length (D) of a some roll in a heat processing zone, and the length (G) between rolls. It is a schematic block diagram which shows an example of the liquid crystal display device to which the thermoplastic film which concerns on this Embodiment is applied.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 ... Film manufacturing apparatus 20 ... Die 24 ... Touch roll 28 ... 1st casting roll 46 ... Heat treatment zone 48a-48d ... Roll 50 ... Liquid crystal display device 52, 56 ... Polarizing plate 68, 80 ... Optical compensation film 84 ... Protective film F ... Thermoplastic film Fa ... Unstretched film Fc ... Transversely stretched film

Claims (14)

  After the thermoplastic film is stretched in the transverse direction, two or more transport rolls are heat-treated in which the ratio (G / D) of roll wrap length (D) to inter-roll length (G) is 0.01 or more and 3 or less. A heat treatment method for a thermoplastic film, characterized in that the zone is transported at a ratio (V2 / V1) of a transport speed (V1) on the inlet side and a transport speed (V2) on the outlet side of 0.6 to 0.999. . In the heat processing method of the thermoplastic film of Claim 1,
A heat treatment method for a thermoplastic film, wherein a ratio (G / D) of the roll wrap length (D) to the length between rolls (G) is 0.05 to 0.9.   The method for heat treating a thermoplastic film according to claim 1 or 2, wherein both ends of the film are fixed on a roll. In the heat processing method of the thermoplastic film of any one of Claims 1-3,
A heat treatment method for a thermoplastic film, wherein the heat treatment is performed at a glass transition temperature (Tg-20) ° C. or higher and (Tg + 50) ° C. or lower. In the heat processing method of the thermoplastic film of any one of Claims 1-4,
A method for heat-treating a thermoplastic film, wherein the transverse stretching (transverse stretching) ratio is 1.1 to 3 times. In the heat processing method of the thermoplastic film of any one of Claims 1-5,
A method for heat-treating a thermoplastic film, wherein the thermoplastic film comprises cellulose acylate, a cycloolefin, a lactone ring-containing polymer, and a polycarbonate polymer. In the heat processing method of the thermoplastic film of any one of Claims 1-6,
A method for heat-treating a thermoplastic film, wherein the thermoplastic film is formed by a melt film-forming method. In the heat processing method of the thermoplastic film of any one of Claims 1-7,
A method for heat-treating a thermoplastic film, wherein the thermoplastic film has a surface roughness (Ra) of from 0.005 μm to 0.04 μm. In the heat processing method of the thermoplastic film of any one of Claims 1-8,
A method for heat-treating a thermoplastic film, wherein the thermoplastic film is formed by a touch roll film forming method. In the heat processing method of the thermoplastic film of any one of Claims 1-9,
A method for heat treating a thermoplastic film, wherein Re of the thermoplastic film after the heat treatment is 50 to 150 nm.   The Rth / Re ratio is 0.5 or more and less than 1, the Rth / Re ratio range measured in the width direction is 0.01 or more and 0.1 or less, and the thermal dimensional change at 80 ° C. for 200 hours is 0.001% or more and 0.00. A thermoplastic film characterized by being 3% or less.   The thermoplastic film according to claim 10, which is prepared by the method for heat-treating a thermoplastic film according to claim 1.   A polarizing plate using the thermoplastic film according to claim 11, an optical compensation film for a liquid crystal display panel, an antireflection film, and a liquid crystal display device.   After the thermoplastic film is stretched in the transverse direction, two or more transport rolls are heat-treated in which the ratio (G / D) of roll wrap length (D) to inter-roll length (G) is 0.01 or more and 3 or less. A method for producing a thermoplastic film, characterized in that the zone is conveyed at a ratio (V2 / V1) of an inlet side conveying speed (V1) to an outlet side conveying speed (V2) of 0.6 or more and 0.999 or less. .

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