JP2012025167A - Long stretched film, long lamination film, polarizing plate, and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wide and long stretched film having a prescribed orientation angle, a large Nz coefficient over the entire width, and small variations in the orientation angle and the Nz coefficient in the entire width.SOLUTION: The long stretched film is made of a transparent resin having a positive intrinsic birefringence. An average orientation angle θ is in a range of 10 to 80 ° relative to the width direction, and an average Nz coefficient is in a range exceeding 2.0 and equal to or lower than 10.0.

Description

The present invention relates to a liquid crystal display device using stretched long film, the long laminate film and the polarizing plate using the stretched film of the long scale, a polarizing plate.

  Various retardation films are used in liquid crystal display devices in order to improve performance. This retardation film is a liquid crystal display device in which the slow axis is inclined at various specific angles with respect to the polarization transmission axis of the polarizer, the polarization transmission axis of the liquid crystal cell, etc. Installed. The tilt angle of the slow axis may be an angle that is neither parallel to nor perpendicular to the side of the display device.

  By the way, as a method for obtaining a retardation film oriented at an angle that is not parallel or perpendicular to the side as described above, a transparent resin film is oriented by longitudinal stretching or lateral stretching to form a long stretched film. After obtaining, a method of cutting into a rectangular shape at a predetermined angle with respect to the side of the stretched film is widely known. However, this method has a problem that even if the cutting is performed so as to obtain the maximum area, a cutting loss always occurs, and the utilization efficiency of the stretched film is low.

  On the other hand, in the case of a long stretched film oriented obliquely at a predetermined angle, it can be cut parallel to the side edges, and the utilization efficiency of the stretched film is increased. Various methods have been proposed for obtaining such an obliquely oriented film by stretching.

  For example, Patent Document 1 discloses that an optical polymer film is stretched by holding both ends of a continuously supplied polymer film by holding means, and stretching the holding means while moving the holding means in the longitudinal direction of the film. In the method, the trajectory L1 of the holding means from the substantial holding start point to the substantial holding release point at one end of the polymer film and the substantial holding start point to the substantial holding release point at the other end of the polymer film. The distance L between the holding means trajectory L2 and the two substantially holding release points satisfies the relationship of | L2-L1 |> 0.4W, maintains the support of the polymer film, and has a volatile content of 5%. There is disclosed a method for stretching an optical polymer film, characterized in that, after stretching in the presence of the above-described state, the volatile content rate is reduced while shrinking.

  Further, in Patent Document 2, it is obtained by stretching a long film made of a thermoplastic resin, and the optical axis (orientation axis) is not parallel to or perpendicular to the winding direction of the long film. In the region where the film is substantially stretched, the moving speeds at the opposite ends in the width direction are equal and the moving distances are different in the region where the film is substantially stretched. Stretching is performed so that at least one of a pair of jigs holding both ends in the width direction is moved on a wavy rail with respect to the film surface. Is disclosed. Further, Patent Document 2 discloses that this stretching step may be performed after repeating this stretching step several times or after stretching in the longitudinal direction or the transverse direction in advance.

JP 2002-86554 A JP 2003-232929 A

  However, when producing a stretched film having a large orientation angle with respect to the width direction of the long stretched film by these oblique stretching methods, the variation in the orientation angle in the width direction of the long stretched film increases, and Nz The coefficient variation also increases. Therefore, it has been difficult to industrially mass-produce a wide optical film having a small variation in orientation angle and Nz coefficient over the entire width.

  An object of the present invention is to provide a wide stretched film having a predetermined orientation angle, a large Nz coefficient over the entire width, and a small variation in the orientation angle and the Nz coefficient over the entire width, and the long stretched film. It is to provide a long laminated film and a polarizing plate used, a liquid crystal display using the polarizing plate, and a method for producing the long stretched film.

  As a result of studies to achieve the above-mentioned object, the present inventor has used a combination of oblique stretching and simultaneous biaxial stretching for stretching a long transparent resin film made of a thermoplastic resin, thereby obtaining a predetermined orientation angle. It has been found that a wide stretched film having a large Nz coefficient over the entire width and a small variation in orientation angle and Nz coefficient over the entire width can be obtained, and based on this finding, the present invention is completed. It has come.

That is, according to the first aspect of the present invention, it is made of a transparent resin having a positive intrinsic birefringence , the average orientation angle θ is in the range of 10 to 80 ° with respect to the width direction, and the average Nz coefficient is 2.0. And a long stretched film in the range of 10.0 or less is provided.

In a first aspect of the present invention, it is preferable upper limit value of the average Nz coefficient of 3.0. The transparent resin having a positive intrinsic birefringence is preferably an alicyclic olefin polymer. The average orientation angle θ is preferably in the range of 40 to 50 ° with respect to the width direction.

  According to the second aspect of the present invention, there is provided a long laminated film in which the long stretched film according to the first aspect described above and the long polarizing film are laminated with their longitudinal directions aligned. Is done.

  In the 3rd viewpoint of this invention, the polarizing plate formed by cutting out the elongate laminated film concerning the above-mentioned 2nd viewpoint to a predetermined magnitude | size is provided.

  According to a fourth aspect of the present invention, there is provided a VA mode or OCB mode liquid crystal display device comprising the polarizing plate according to the third aspect described above.

  The long stretched film of the present invention has a predetermined orientation angle, a large Nz coefficient over the entire width, and a small variation in the orientation angle and the Nz coefficient over the entire width. Moreover, since the elongate laminated film of this invention has laminated | stacked the elongate stretched film of this invention with the elongate polarizing film, it has a favorable optical characteristic. The polarizing plate of the present invention, when used in a liquid crystal display device, particularly a reflective liquid crystal display device of a specific mode such as VA mode, widens the viewing angle of the display screen, reduces the contrast of the display screen, Coloring can be prevented.

  In addition, the liquid crystal display device of the present invention has a wide viewing angle of the display screen and good contrast. Further, according to the method for producing a long stretched film of the present invention, a wide stretched film having a predetermined orientation angle, a large Nz coefficient over the entire width, and a small variation in the orientation angle and the Nz coefficient over the entire width. Can be manufactured with high accuracy.

It is a figure which shows the structure of the tenter stretching machine for diagonal stretching concerning embodiment of this invention. It is a figure which shows the structure of the tenter stretching machine for simultaneous biaxial stretching concerning embodiment of this invention.

Hereinafter, the elongate stretched film which concerns on embodiment of this invention is demonstrated. The elongated stretched film according to the embodiment of the present invention is made of a transparent resin having a long intrinsic birefringence composed of a thermoplastic resin, and the average orientation angle θ is the width direction of the elongated stretched film. range of 10 to 80 ° with respect to, preferably in the range of 40 to 50 °, an average Nz coefficient 2.0 exceeds 10.0, preferably in the range of the upper limit value of the average Nz coefficient 3. 0.
In the present embodiment, the long refers to a film having a length of at least about 5 times the width direction of the film or laminate, preferably having a length of 10 times or more, specifically Refers to those having a length that is wound in a roll and stored or transported.

  The thermoplastic resin used for the stretched film according to the present embodiment is not particularly limited as long as it is a transparent resin. Polycarbonate resin, polyether sulfone resin, polyethylene terephthalate resin, polyimide resin, polymethyl methacrylate resin, polysulfone resin, polysulfone resin Examples include arylate resin, polyethylene resin, polyvinyl chloride resin, diacetyl cellulose, triacetyl cellulose, polystyrene resin, polyacrylic resin, and alicyclic olefin polymer. Among these, a resin having a positive intrinsic birefringence value is preferable, and an alicyclic olefin polymer is more preferable.

  The alicyclic olefin polymer suitably used in the present invention is an amorphous resin having an alicyclic structure in the main chain and / or side chain.

  Examples of the alicyclic structure in the alicyclic olefin polymer include a saturated alicyclic hydrocarbon (cycloalkane) structure and an unsaturated alicyclic hydrocarbon (cycloalkene) structure. From the viewpoint of mechanical strength, heat resistance, and the like. A saturated alicyclic hydrocarbon (cycloalkane) structure is preferred. The number of carbon atoms constituting the alicyclic structure is not particularly limited, but is usually 4 to 30, preferably 5 to 20, more preferably 5 to 15, when the mechanical strength, heat resistance, In addition, the moldability characteristics of the film are highly balanced and suitable.

  The ratio of the repeating unit having an alicyclic structure constituting the alicyclic olefin polymer is preferably 55% by weight or more, more preferably 70% by weight or more, and particularly preferably 90% by weight or more. It is preferable from a viewpoint of transparency and heat resistance that the ratio of the repeating unit which has an alicyclic structure in an alicyclic olefin polymer exists in this range.

  Specific examples of the alicyclic olefin polymer include a norbornene resin, a monocyclic olefin resin, a cyclic conjugated diene resin, a vinyl alicyclic hydrocarbon resin, and hydrides thereof. Among these, norbornene resin can be suitably used because of its good transparency and moldability.

  Examples of the norbornene resin include a ring-opening polymer of a monomer having a norbornene structure, a ring-opening copolymer of a monomer having a norbornene structure and another monomer, or a hydride thereof; Examples thereof include addition polymers of monomers having a monomer, addition copolymers of monomers having a norbornene structure and other monomers, and hydrides thereof. Among these, a ring-opening (co) polymer hydride of a monomer having a norbornene structure is particularly suitable from the viewpoints of transparency, moldability, heat resistance, low hygroscopicity, dimensional stability, lightness, and the like. Can be used.

Examples of monomers having a norbornene structure include bicyclo [2.2.1] hept-2-ene (common name: norbornene), tricyclo [4.3.0.1 ² , ⁵ ] deca-3,7-diene. (common name: dicyclopentadiene), 7,8-tricyclo [4.3.0.1 ^{2, 5]} dec-3-ene (common name: methanolate tetrahydrofluorene), tetracyclo [4.4.0. 1 ² , ⁵ . 1 ⁷ , ¹⁰ ] dodec-3-ene (common name: tetracyclododecene), and derivatives of these compounds (for example, those having a substituent in the ring). Here, examples of the substituent include an alkyl group, an alkylene group, and a polar group. Moreover, these substituents may be the same or different and a plurality may be bonded to the ring. Monomers having a norbornene structure can be used singly or in combination of two or more.

  Examples of the polar group include a hetero atom or an atomic group having a hetero atom. Examples of the hetero atom include an oxygen atom, a nitrogen atom, a sulfur atom, a silicon atom, and a halogen atom. Specific examples of the polar group include a carboxyl group, a carbonyloxycarbonyl group, an epoxy group, a hydroxyl group, an oxy group, an ester group, a silanol group, a silyl group, an amino group, a nitrile group, and a sulfone group. To obtain a film with a small saturated water absorption rate. It is preferable that the amount of polar groups is small, and it is more preferable that there are no polar groups.

  Other monomers capable of ring-opening copolymerization with monomers having a norbornene structure include monocyclic olefins such as cyclohexene, cycloheptene, and cyclooctene and derivatives thereof; cyclic conjugated dienes such as cyclohexadiene and cycloheptadiene; Derivatives thereof; and the like.

  A ring-opening polymer of a monomer having a norbornene structure and a ring-opening copolymer of a monomer having a norbornene structure and another monomer copolymerizable with the monomer have a known ring-opening polymerization catalyst. It can be obtained by (co) polymerization in the presence.

  Examples of other monomers that can be addition copolymerized with a monomer having a norbornene structure include α-olefins having 2 to 20 carbon atoms such as ethylene, propylene, and 1-butene, and derivatives thereof; cyclobutene, cyclopentene, And cycloolefins such as cyclohexene and derivatives thereof; non-conjugated dienes such as 1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, and the like. These monomers can be used alone or in combination of two or more. Among these, α-olefin is preferable and ethylene is more preferable.

  An addition polymer of a monomer having a norbornene structure and an addition copolymer of a monomer having a norbornene structure with another monomer copolymerizable with a monomer having a norbornene structure are prepared in the presence of a known addition polymerization catalyst. It can be obtained by polymerization.

  Hydrogenated product of ring-opening polymer of monomer having norbornene structure, hydrogenated product of ring-opening copolymer of monomer having norbornene structure and other monomer capable of ring-opening copolymerization, norbornene structure The hydride of an addition polymer of a monomer having a monomer, and the hydride of an addition copolymer of a monomer having a norbornene structure and another monomer capable of addition copolymerization with these ring-opening (copolymerization) ) A known hydrogenation catalyst containing a transition metal such as nickel or palladium is added to a polymer or addition (co) polymer solution, and brought into contact with hydrogen, so that the carbon-carbon unsaturated bond is preferably 90% or more. It can be obtained by hydrogenation.

  Examples of the alicyclic olefin polymer include those described in JP-A No. 05-310845, JP-A No. 05-097978, and US Pat. No. 6,511,756.

The thermoplastic resin used in the present invention is not particularly limited by its molecular weight. The molecular weight of the thermoplastic resin is a weight average molecular weight (Mw) of polyisoprene (in terms of polystyrene when the solvent is toluene) measured by gel permeation chromatography using cyclohexane (toluene if the resin is not dissolved) as a solvent. ) Is usually 10,000 to 100,000, preferably 15,000 to 80,000, more preferably 20,000 to 50,000. When the weight average molecular weight is in such a range, the mechanical strength and formability of the film are highly balanced, which is preferable. The thermoplastic resin used in the present embodiment has a glass transition temperature of preferably 80 ° C. or higher, more preferably 100 to 250 ° C. The absolute value of the photoelastic coefficient of the thermoplastic resin is preferably 10 × 10 ⁻¹² Pa ⁻¹ or less, more preferably 7 × 10 ⁻¹² Pa ⁻¹ or less, and particularly preferably 4 × 10 ⁻¹² Pa ^−1. It is as follows. The photoelastic coefficient C is a value represented by C = Δn / σ where birefringence is Δn and stress is σ. When a transparent resin having a photoelastic coefficient in such a range is used, variation in retardation Re in the in-plane direction of the stretched film can be reduced. Furthermore, when such a stretched film is applied to a liquid crystal display device, it is possible to suppress a phenomenon in which the hue of the end portion of the display screen of the liquid crystal display device changes.

  The thermoplastic resin used in this embodiment is a colorant such as a pigment or a dye, a fluorescent brightener, a dispersant, a heat stabilizer, a light stabilizer, an ultraviolet absorber, an antistatic agent, an antioxidant, a lubricant, and a solvent. The compounding agent such as may be appropriately blended. Here, the compounding amount of the compounding agent is not particularly limited, and is 0 to 5% by weight in the thermoplastic resin.

In the present embodiment, the retardation Re in the in-plane direction of the stretched film is about 100 to 300 nm, and an optimum value is selected within this range depending on the design of the display device used. Incidentally, retardation Re in the in-plane direction, the slow axis direction of the refractive indices n _x in the plane, the difference between the refractive index n _y in the direction perpendicular to the slow axis in the plane of the mean thickness d of the film a multiplication value _{(Re = (n x -n y} ) × d).

  In the present embodiment, the variation in retardation Re in the in-plane direction of the stretched film is preferably within 10 nm, more preferably within 5 nm, and particularly preferably within 2 nm. By setting the variation of the retardation Re in the in-plane direction within the above range, the display quality can be improved when used as a retardation film for a liquid crystal display device.

  The in-plane retardation Re is measured using a commercially available phase difference measurement device at a light incident angle of 0 ° (incident light beam and the stretched film surface are perpendicular to each other) at an interval of 50 mm in the width direction. The average value is defined as an in-plane retardation Re. Further, the variation in retardation Re in the in-plane direction is a value obtained by subtracting the minimum value from the maximum value of each measurement value.

  As described above, the stretched film according to the present embodiment has a range of 10 to 80 °, preferably 40 to 40, when the average orientation angle θ is 0 ° in the width direction of the film, that is, the direction perpendicular to the longitudinal direction of the film. Although it is within the range of 50 °, the optimum value within this range is selected according to the design of the display device to be used, like the above-mentioned in-plane average retardation value.

  In the stretched film according to the present embodiment, the variation in the orientation angle is 1.0 ° or less, preferably 0.8 ° or less, at least 1300 mm in the width direction. When a stretched film having a variation in the orientation angle θ exceeding 1.0 ° is bonded to a polarizing plate to obtain a circularly polarizing plate, and this is installed in a liquid crystal display device, light leakage occurs and the contrast may be lowered. is there. In the present embodiment, the orientation angle is the smaller of the angles formed by the film width direction and the orientation axis (slow axis in the film plane). In addition, average orientation angle | corner (theta) measures the orientation angle | corner of a stretched film at a 50 mm space | interval in the width direction using a commercially available polarizing microscope, and makes it an average value. The variation in the orientation angle is a value obtained by subtracting the minimum value from the maximum value of each measurement value.

Stretched film according to the present embodiment, the refractive slow axis direction of the refractive indices n _x in the plane of the _film, the refractive index in a direction perpendicular to the slow axis in the film plane n _y, in the thickness direction of the film when the rate was _{n z, (n x -n z} ) / (n x -n y) average Nz coefficient of 1.5 to 30.0 range represented by, preferably the lower limit value 1.7 However, the optimum value within this range is selected depending on the design of the liquid crystal display device used. The average Nz coefficient is more preferably in a range exceeding 2.0, and further preferably in a range exceeding 2.1. A more preferable upper limit value of the average Nz coefficient is 10.0, and a more preferable upper limit value is 3.0. Since the stretched film according to the present embodiment has a large average Nz coefficient, a polarizing plate using the stretched film is converted into a vertical alignment (VA) mode, a multi-domain vertical alignment (MVA) mode, and an optical compensation. Good viewing angle characteristics can be obtained when used in a liquid crystal display device having a specific display mode of the ited bend (OCB) mode. In the present embodiment, the Nz coefficient can be efficiently within the above range even if the film is thin.

  In the stretched film according to the present embodiment, the variation of the Nz coefficient is 0.10 or less, preferably 0.09 or less, more preferably 0.08 or less, at least at 1300 mm in the width direction. If the variation of the Nz coefficient exceeds 0.10, if this is incorporated into a liquid crystal display device, it causes a reduction in display quality such as color unevenness. In addition, an average Nz coefficient measures the Nz coefficient (it calculates | requires from the refractive index measured with the phase difference measuring apparatus) of a stretched film using a commercially available phase difference measuring apparatus at a 50 mm space | interval in the width direction, and makes it an average value. . Further, the variation of the Nz coefficient is a value obtained by subtracting the minimum value from the maximum value of each measurement value.

  In the present embodiment, the average thickness of the stretched film is preferably 20 to 200 μm, more preferably 30 to 80 μm, and particularly preferably 30 to 50 μm from the viewpoint of mechanical strength and the like. Moreover, since the thickness unevenness in the width direction of the stretched film affects the availability of winding, it is preferably 3 μm or less, more preferably 2 μm or less, and even more preferably 0.7 μm or less. Here, the average thickness is measured using a commercially available thickness measuring device at intervals of 50 mm in the width direction, and the average value is defined as the average thickness. The thickness unevenness is a value obtained by subtracting the minimum value from the maximum value of each measurement value.

  In the present embodiment, the long stretched film has a width of at least 1300 mm, preferably at least 1500 mm. In the production process, a long stretched film is arbitrarily created by cutting off both ends in the width direction after stretching. In this case, the width of the film can be a dimension after cutting off both ends. .

In the stretched film according to the present embodiment, the content of residual volatile components is preferably 0.1% by weight or less, more preferably 0.05% by weight or less, and further preferably 0.02% by weight or less. If the content of residual volatile components is large, the optical characteristics may change over time. The content of volatile components in the above range, dimensional stability is improved, the in-plane direction retardation Re and thickness direction retardation _{Rth (= ((n x +} n y) / 2-n z) × d ; n _x is the in-plane slow axis direction of the refractive index; over time d is the average thickness of the film); n _y is a refractive index in a direction perpendicular to the slow axis in a plane; n _z is the thickness direction of the refractive index The change can be reduced, and further, deterioration of the circularly polarizing plate and the liquid crystal display device provided with the stretched film can be suppressed, and the display image can be kept in a good state for a long time.

  The volatile component is a substance having a molecular weight of 200 or less contained in a trace amount in the film, and examples thereof include residual monomers and solvents. The content of the volatile component can be quantified by dissolving the film in chloroform and analyzing it by gas chromatography as the total of substances having a molecular weight of 200 or less contained in the film.

  In the present embodiment, the stretched film has a saturated water absorption rate of preferably 0.03% by weight or less, more preferably 0.02% by weight or less, and particularly preferably 0.01% by weight or less.

When the saturated water absorption is in the above range, the temporal change of the in-plane retardation Re and the thickness direction retardation Rth can be reduced, and further the deterioration of the circularly polarizing plate and the liquid crystal display device can be suppressed, and the display image can be reduced. It can be kept in good condition for a long time. Here, the saturated water absorption is measured in accordance with JIS K7209 by immersing a film specimen in water at 23 ° C. for 24 hours, and measuring the mass change of the specimen, that is, the difference in mass before and after immersion. And is a value expressed as a percentage before immersion.

Next, the 1st manufacturing method of the elongate stretched film which concerns on this Embodiment is demonstrated. In this first production method, a long transparent resin film (hereinafter sometimes referred to as “raw fabric”) composed of a thermoplastic resin is stretched, and the average orientation angle θ ₁ is the end of stretching in this step. The first step of obtaining a first stretched film in the range of 5 to 75 °, preferably 5 to 40 ° with respect to the width direction at the position, and the first stretched film obtained from the first step are simultaneously biaxially stretched. And a second step of obtaining a second stretched film having an average orientation angle θ _{2 in} the range of 10 to 80 °, preferably 40 to 50 ° with respect to the width direction.

  The long original fabric composed of the thermoplastic resin used in the first step can be obtained by a known method, for example, a cast molding method, an extrusion molding method, an inflation molding method, or the like. Of these, the extrusion method is preferable because it has a small amount of residual volatile components and is excellent in dimensional stability. This original fabric may be a single layer or a laminated film of two or more layers. The laminated film can be obtained by a known method such as a coextrusion molding method, a film lamination method, or a coating method. Of these, the coextrusion method is preferred. In order to make the optical properties after stretching uniform, it is necessary to reduce the thickness unevenness of the raw material as much as possible. The thickness of the original fabric is usually 40 to 500 μm, preferably 50 to 300 μm, more preferably 50 to 200 μm.

  The first step is performed using a tenter stretching machine 2 for oblique stretching shown in FIG. A tenter stretching machine 2 for oblique stretching shown in FIG. 1 includes a drawing roll (winding body) 10, a winding roll 12, a temperature-controlled room 14 composed of a preheating zone A 1, a stretching zone B 1, and a fixed zone C 1, And a rail 16 on which a grip clip (not shown) for transporting the film travels.

  The gripping clip grips both ends of the raw fabric 11 fed out from the pulling roll 10, and guides the raw fabric 11 into the temperature-controlled room 14 composed of the preheating zone A1, the stretching zone B1, and the fixed zone C1, and stretches it obliquely. Then, the obliquely stretched film (first stretched film) 13 is opened before the winding roll 12. The obliquely stretched film 13 released from the grip clip is taken up by the take-up roll 12. The pair of left and right rails 16 have a continuous endless track without a terminal, and are configured to sequentially return the grip clips with the obliquely stretched film 13 opened from the exit side of the temperature-controlled room 14 to the entrance side.

In the tenter stretching machine 2 for oblique stretching according to the present embodiment, as shown in FIG. 1, the film traveling direction (film feeding direction) of the preheating zone A1 is the film traveling direction (film winding direction) of the fixed zone C1. In contrast, the angle θ _{A is} inclined. That is, the angle θ _A is appropriately selected within the range of 5 to 75 °, preferably 5 to 40 °, so that the direction in which the original fabric 11 is drawn out from the pulling roll 10 and the obliquely stretched film on the winding roll 12 The direction in which 13 is wound is configured to be non-parallel. In the tenter stretching machine 2 for oblique stretching shown in FIG. 1, the rail 16 is bent on the left side with respect to the traveling direction of the film, but the film is symmetrical with respect to the line in the film traveling direction of the preheating zone A1 in FIG. The rail may be bent on the right side.

It is preferable that the stretching zone B1 is linear without changing the film traveling direction as in the tenter stretching machine 2 for oblique stretching. By not changing the running direction of the film, the optical properties of the stretched film can be improved. The opening angle of the rail 16 can be appropriately selected according to the draw ratio. Film running direction of the fixing zone C1 (film take-up direction) is inclined at an angle of the theta _A as shown in FIG. 1 from the film running direction in the preheating zone A1 (film feeding direction). For this reason, the upper gripping clip in the figure goes farther than the lower gripping clip, whereby oblique stretching is performed.

  That is, the raw fabric 11 is stretched by the tension from the gripping clip while passing through the temperature-controlled room 14 including the preheating zone A1, the stretching zone B1, and the fixing zone C1. The preheating zone A1, the stretching zone B1 and the fixed zone C1 can be set independently of each other, and the temperature is normally kept constant in each zone. Although the temperature of each zone can be selected as appropriate, the preheating zone is Tg to Tg + 30 (° C.) and the stretching zone is Tg to Tg + 20 (° C.) with respect to the glass transition temperature Tg (° C.) of the thermoplastic resin constituting the raw fabric 11. The fixed zone is Tg to Tg + 15 (° C.).

  In the present embodiment, a temperature difference in the width direction may be applied in the stretching zone B1 in order to control thickness unevenness in the width direction. In particular, it is preferable that the temperature in the vicinity of the grip clip is higher than that in the center of the film. In order to create a temperature difference in the width direction in the stretching zone B1, a method of adjusting the opening degree of the nozzle that sends warm air into the temperature-controlled room 14 so as to make a difference in the width direction, or heating control by arranging heaters in the width direction is performed. A known method such as can be used. The lengths of the preheating zone A1, the stretching zone B1 and the fixed zone C1 can be appropriately selected. Usually, the length of the preheating zone A1 is usually 100 to 150% with respect to the length of the stretching zone B1, and the length of the fixed zone C1. Is usually 50 to 100%.

  A partition plate having a slit through which the film can pass is installed at the boundary 18 between the preheating zone A1 and the stretching zone B1 and at the boundary 20 between the stretching zone B1 and the fixing zone C1. The preheating zone A1 is a zone in which the film is conveyed while warming the film without substantially changing the film length in the direction perpendicular to the film running direction of the preheating zone A1. The film running direction in the preheating zone A1 is a direction parallel to the film feeding direction, and is generally orthogonal to the rotation axis of the drawing roll 10.

  The stretching zone B1 is a zone in which the film is conveyed while increasing the film length in a direction perpendicular to the film traveling direction of the stretching zone B1. The film running direction in the stretching zone B1 is stretched from the middle point of the film at the boundary between the preheating zone A1 and the stretching zone B1 in the rail arrangement in which the stretching zone B1 spreads at a constant angle without changing the inclination as shown in FIG. It is the direction of a straight line connected to the midpoint of the film at the boundary between zone B1 and fixed zone C1.

  The fixing zone C1 is a zone in which the film is conveyed while cooling the film without substantially changing the film length in the direction perpendicular to the film traveling direction of the fixing zone C1. The film traveling direction of the fixed zone C <b> 1 is a direction parallel to the film winding direction, and is generally orthogonal to the rotation axis of the winding roll 12.

  In the manufacturing method according to the present embodiment, it is preferable that the film surfaces in the preheating zone A1, the stretching zone B1, and the fixing zone C1 are substantially parallel to each other. That is, the film drawn from the drawing roll 10 is preferably twisted and passed through the preheating zone A1, the stretching zone B1, and the fixing zone C1, and is taken up by the winding roll 12.

  In the manufacturing method according to the present embodiment, the traveling speeds of the grip clips are substantially equal at both ends of the film. The traveling speed of the grip clip can be selected as appropriate, but is usually 10 to 100 m / min. The traveling speed of the gripping clip is kept constant from when the film is gripped by the gripping clip until the film is released. The difference in travel speed between the pair of left and right grip clips is usually 1% or less, preferably 0.5% or less, more preferably 0.1% or less of the travel speed. When the gripping clip travels on the rail 16 at such a traveling speed, variations in the optical characteristics of the stretched film can be prevented.

The stretched film (first stretched film) 13 that has passed through the temperature-controlled room as described above is released from the grip clip before the take-up roll 12 and is taken up by the take-up roll 12. In this way, an obliquely stretched film having an average orientation angle θ _{1 in} the range of 5 to 75 °, preferably 5 to 40 ° with respect to the width direction at the stretching end position in this step is produced.

  In the present embodiment, the first stretched film is wound around the take-up roll 12 and supplied to the next drawing step (second step) after forming the wound body. You may supply directly to the next extending process, without taking.

The draw ratio in the first step is usually 1.3 to 2.0 times, preferably 1.5 to 1.8 times. When the draw ratio R is within this range, thickness unevenness in the width direction is preferably reduced. The said draw ratio can be calculated | required from the length change amount of the width direction of a stretched film. Specifically, the first step width before the raw W _0, and the width of the first stretched film after the first step and W _1, stretching magnification R can be obtained by W _{1 /} W _0.

  Next, the second step for performing simultaneous biaxial stretching will be described. This second step is performed using a tenter stretching machine 4 for simultaneous biaxial stretching shown in FIG. The tenter stretching machine 4 for simultaneous biaxial stretching shown in FIG. 2 is called a pantograph type tenter stretching machine. Other simultaneous biaxial stretching machines include a screw-type tenter stretching machine and a linear motor-type tenter stretching machine, but only the driving system for widening the gap between the grip clips is different. Therefore, any type of simultaneous biaxial stretching machine can be applied.

  In the tenter stretching machine 4 for simultaneous biaxial stretching shown in FIG. 2, a plurality of grip grips 32 for gripping the ends of an obliquely stretched film (first stretched film) 13 fed from a take-up roll (not shown) are provided as a first stretched film. 13 is provided with an endless link device 34 (not shown in the figure, a part of the link and one endless link are omitted) provided with a plurality of equal-length link devices formed in a fold shape. By driving the device 34 with the sprocket 36 on the inlet side of the first stretched film 13, the endless link device 34 is arranged so as to spread outwardly in the film traveling direction (from left to right in FIG. 2), guide rails 38, 40, 42. The first stretched film 13, which is guided by the guides 44 and 44, gradually widens the gap between the grip clips 32 and grips the end portions thereof, is stretched simultaneously in two longitudinal and transverse directions, and the second stretched film 13 is stretched. Give Lum 46, further remove the end of the second oriented film 46 from the gripping clip 32 is configured to endless linkage 34 so as to return to the inlet side sprocket 36 is driven by the outlet side sprocket 37.

  In the tenter stretching machine 4 for simultaneous biaxial stretching according to the present embodiment, members that support each node of the pantograph between the upper and lower guide rails 38 and 40 in FIG. It is clamped so that it can operate. One set of guide rails 38 and 40 and one set of guide rails 42 and 44 can be slid independently, and by the rail layout that can be made by this sliding, how to extend the grip clip interval in the MD direction (film longitudinal direction), It is comprised so that the spreading method of the holding clip space | interval of TD direction (film width direction) can be adjusted.

  That is, when the distance between the guide rail 40 and the guide rail 44 changes, the opening width of the pantograph changes, and the interval in the MD direction of the grip clip 32 attached to the tip of the pantograph can be adjusted. When the distance between the guide rail 40 and the guide rail 44 is increased, the pantograph of the link device 34 is closed, and the interval between the grip clips 32 in the MD direction is reduced. Conversely, when the distance between the guide rail 40 and the guide rail 44 is shortened, the pantograph of the link device 34 is opened, and the interval between the grip clips 32 in the MD direction is increased. Since each guide rail can slide independently, the distance between the upper guide rail 40 and the guide rail 44 in the figure and the distance between the lower guide rail 40 and the guide rail 44 in the figure are independent. It is possible to adjust the way in which the gap between the upper gripping clips in the MD direction in FIG. 2 and the way to spread the gap between the lower gripping clips in the MD direction in FIG.

  On the other hand, the interval in the TD direction of the grip clip 32 can be adjusted by the distance between the TD directions of the upper and lower guide rails 38 in FIG. Since each guide rail can be slid independently, the spread width of the upper guide rail 38 in the figure in the TD direction upper side (t1 in FIG. 2) and the spread width of the lower guide rail 38 in the downward direction in the TD direction (T2 in FIG. 2) can be made the same or different. In this embodiment, simultaneous biaxial stretching is performed under the stretching conditions such that the orientation in the MD direction remains by adjusting the distance between the guide rails of the tenter stretching machine 4 for simultaneous biaxial stretching.

  In the tenter stretching machine 4 for simultaneous biaxial stretching, a preheating zone A2 that is heated to a temperature suitable for stretching the first stretched film 30, a stretching zone B2 in which stretching is performed with a gap between gripping clips widened, is stretched. The film is divided into fixed zones C2 for stabilizing the stretched state of the film. The temperature in each section is Tg-5 (° C) to Tg + 20 (° C) in the preheating zone A2 and Tg-5 (° C) to Tg + 20 in the stretching zone B2 with respect to the glass transition temperature Tg (° C) of the thermoplastic resin. (° C.), the fixing zone C2 is Tg−5 (° C.) to Tg + 20 (° C.). The draw ratio in the second stretching step is usually 1.1 to 2.0 times, preferably 1.2 to 1.8 times, respectively in the longitudinal direction of the film and the width direction of the film.

The stretched film (second stretched film) that has passed through the tenter stretching machine 4 for simultaneous biaxial stretching as described above is released from the gripping clip 32 before the winding roll (not shown) and wound around the winding roll. . In this way, the average orientation angle θ ₂ is in the range of 10 to 80 °, preferably 40 to 50 ° with respect to the width direction, the average Nz coefficient is in the range of 1.5 to 30, and the width is at least 1300 mm. In the direction, a second stretched film having an orientation angle variation of 1.0 ° or less and an Nz coefficient variation of 0.10 or less is produced. In the 1st manufacturing method of the elongate stretched film which concerns on this Embodiment, the orientation of the film in a 1st process will ease in a 2nd process by employ | adopting simultaneous biaxial stretching in a 2nd process. This can be reduced as much as possible.

  In this embodiment, in the first step oblique stretching and the second step simultaneous biaxial stretching, the retardation Re1 expressed by the first step oblique stretching and the retard developed by the second step simultaneous biaxial stretching. Stretching in each step is performed under stretching conditions such that the foundation Re2 has a relationship of Re1 <Re2. The stretching conditions in each step are determined based on the results obtained by separately performing oblique stretching and simultaneous biaxial stretching using a transparent resin film. By setting Re1 <Re2, the orientation axis of the obtained stretched film is effectively expressed in the direction between the high stretch direction in the simultaneous biaxial stretch (direction in which the stretch ratio is high) and the stretch direction in the oblique stretch. Can be made. In addition, the thickness unevenness of the obtained stretched film can be effectively reduced.

  Moreover, you may trim the both ends of the film currently hold | gripped with the holding | grip clip of a tenter stretching machine before winding up to a winding roll as needed. In addition, before winding, for the purpose of preventing blocking between the films, the masking film may be overlapped and wound up at the same time, or at least one of the stretched films, preferably wound up with tape or the like attached to both ends. Also good. The masking film is not particularly limited as long as it can protect the film, and examples thereof include a polyethylene terephthalate film, a polyethylene film, and a polypropylene film.

Next, the 2nd manufacturing method of the stretched film which concerns on this Embodiment is demonstrated. In this second production method, a long transparent resin film (raw material) composed of a thermoplastic resin is simultaneously biaxially stretched so that the average orientation angle θ ₁ ′ is substantially perpendicular to the width direction. A first step of obtaining a certain biaxially stretched film, and the biaxially stretched film are obliquely stretched so that the average orientation angle θ ₂ ′ is 10 to 80 ° with respect to the width direction at the stretch end position in this step, preferably 40 And a second step of obtaining an obliquely stretched film in a range of ˜50 °. That is, the simultaneous biaxial stretching performed in the second step according to the first manufacturing method is performed first, and the oblique stretching performed in the first step according to the first manufacturing method is performed later. In the description of the second manufacturing method, description will be made using the same reference numerals as those used for the respective components in the description of the first manufacturing method.

In the first step according to the second manufacturing method, the original fabric is simultaneously biaxially stretched using the simultaneous biaxial stretching tenter stretching machine used in the first manufacturing method, and the average orientation angle θ _A biaxially stretched film (first stretched film) having ₁ ′ in a direction substantially perpendicular to the width direction is produced. The direction substantially perpendicular to the width direction in the first step is a direction within ± 3 °, preferably ± 1 °, with respect to the direction perpendicular to the width direction of the original fabric. In addition, the draw ratio in a 1st extending | stretching process is 1.1 to 2.0 times normally respectively in the longitudinal direction of a film, and the width direction of a film, Preferably it is 1.2 to 1.8 times.

Next, using the tenter stretching machine 2 for oblique axis stretching used in the first production method, the simultaneous biaxially stretched film is obliquely stretched, for example, 5 to 75 °, preferably 5 to the film width direction. Stretched in the direction of 40 °, an oblique orientation film (second orientation) having an average orientation angle θ ₂ ′ in the range of 10 to 80 °, preferably 40 to 50 ° with respect to the width direction at the drawing end position in this step. Stretched film). In the second step, the film feeding direction is inclined with respect to the film winding direction at an angle θ _A (5 ≦ θ _A ≦ 75 °, preferably 5 ≦ θ _A ≦ 40 °). Moreover, the draw ratio in a 2nd process is 1.3-2.0 times normally, Preferably it is 1.5-1.8 times. The stretching in the simultaneous biaxial stretching in the first step and the oblique stretching in the second step is performed under the same stretching conditions as in the first manufacturing method.

By passing through the first step and the second step, the average orientation angle θ ₂ ′ is in the range of 10 to 80 °, preferably 40 to 50 ° with respect to the width direction, and the average Nz coefficient is 1.5 to 30. In the width direction of at least 1300 mm, a second stretched film having an orientation angle variation of 1.0 ° or less and an Nz coefficient variation of 0.10 or less is produced.

  According to the method for producing a long stretched film of the present embodiment, since the oblique stretching is performed at a small angle with respect to the width direction of the film, the variation in the orientation angle and the Nz coefficient can be reduced. In addition, the stretched film can be widened even when stretched to a small extent, and the length of the stretched zone (and hence the length of the rail of the stretching machine) can be shortened. In addition, since the simultaneous biaxial stretching is performed under stretching conditions such that the orientation in the direction perpendicular to the width direction of the film remains, a large orientation angle and Nz coefficient can be obtained.

  Furthermore, according to the manufacturing method of the elongate stretched film of this Embodiment, the orientation axis | shaft of the finally obtained stretched film is obtained by the orientation direction of the obliquely stretched film obtained by oblique stretching, and simultaneous biaxial stretching. It can be expressed in the direction between the orientation direction of the biaxially stretched film. Moreover, the thickness nonuniformity of the stretched film finally obtained can be made small in the above ranges.

  The long laminated film according to the embodiment of the present invention is formed by laminating the long stretched film according to the above-described embodiment and the long polarizing film. Here, the polarizing film transmits one of two linearly polarized light intersecting at right angles. For example, a hydrophilic polymer film such as a polyvinyl alcohol film or an ethylene vinyl acetate partially saponified film adsorbed a dichroic substance such as iodine or a dichroic dye and uniaxially stretched, the hydrophilic polymer film Examples include uniaxially stretched and dichroic substances adsorbed, and polyene oriented films such as polyvinyl alcohol dehydrated products and polyvinyl chloride dehydrochlorinated products. Other examples include reflective polarizers such as grid polarizers and anisotropic multilayer films. The thickness of the polarizing film is usually 5 to 80 μm.

  The stretched film according to this embodiment may be laminated on both sides of the polarizing film or on one side, and the number of laminated layers is not particularly limited, and two or more may be laminated. When a stretched film is laminated on only one side of the polarizing film, a protective film may be laminated on the remaining one side with an appropriate adhesive layer for the purpose of protecting the polarizing film. An appropriate transparent film can be used as the protective film. Among them, a film having a resin excellent in transparency, mechanical strength, thermal stability, moisture shielding property, etc. is preferably used. Examples of the resin include acetate polymers such as triacetyl cellulose, alicyclic olefin polymers, chain polyolefins, polycarbonates, polyesters such as polyethylene terephthalate, polyvinyl chloride, polystyrene, polyacrylonitrile, polysulfone, polyethersulfone, polyamide. , Polyimide, acrylic polymer and the like.

  A preferred manufacturing method for obtaining a long laminated film according to the present embodiment is that the film is drawn while simultaneously drawing the film from the wound body of the stretched film and the wound body of the polarizing film according to the present embodiment. It is a method including making a film and this polarizing film contact | adhere. An adhesive can be interposed in the adhesion surface between the stretched film and the polarizing film. As a method for bringing the stretched film and the polarizing film into close contact with each other, there is a method in which the stretched film and the polarizing film are passed through and pressed between nips of two parallelly arranged rolls.

  The long laminated film according to the present embodiment is cut into a desired size according to the usage pattern and used as a polarizing plate. In this case, since the film can be cut out along a direction perpendicular or parallel to the winding direction of the long film, the stretched film can be used without waste.

  A liquid crystal display device according to an embodiment of the present invention includes a polarizing plate formed by cutting a long laminated film according to the present embodiment into a predetermined size. An example of the liquid crystal display device includes a liquid crystal panel that can change a polarization transmission axis by adjusting a voltage and a circularly polarizing plate that is disposed so as to sandwich the liquid crystal panel. The stretched film described above is used as a retardation plate in a liquid crystal display device for optical compensation, polarization conversion, and the like. In order to send light to the liquid crystal panel, the liquid crystal display device is usually provided with a backlight device in the transmissive liquid crystal display device and a reflector in the reflective liquid crystal display device on the back side of the display surface. Examples of the backlight device include a cold cathode tube, a mercury flat lamp, a light emitting diode, and an EL.

  As the liquid crystal display device according to this embodiment, a reflective liquid crystal display device including a reflective liquid crystal panel is preferable. Examples of the display mode of the liquid crystal panel include a vertical alignment (VA) mode, a multi-domain vertical alignment (MVA) mode, and an optically compensated bend (OCB) mode.

  In the liquid crystal display device of the present invention, other appropriate components such as a prism array sheet, a lens array sheet, a light diffusion plate, a light guide plate, a diffusion sheet, and a brightness enhancement film are arranged in one layer or two or more layers at appropriate positions. can do.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to the following examples.

  Evaluation in this example is performed by the following method.

(1) Variation in average orientation angle θ and orientation angle Using a polarizing microscope (manufactured by Olympus, BX51), measured at intervals of 50 mm in the width direction of the film, measured in-plane slow axis, direction of slow axis The average value of the angle (orientation angle) formed by the film and the width direction of the film was determined, and this was defined as the average orientation angle θ. The variation in the orientation angle was defined as the difference between the maximum value and the minimum value of the orientation angle.

(2) Retardation in average in-plane direction, average Nz coefficient, and variation in Nz coefficient Using a phase difference meter (KOBRA-21ADH, manufactured by Oji Scientific Instruments), Re and Nz coefficients were measured at intervals of 50 mm in the width direction of the film. The average value was obtained for each. The variation of the Nz coefficient is the difference between the maximum value and the minimum value of the Nz coefficient.

(3) Display characteristics of a liquid crystal display device using a circularly polarizing plate according to the example. A long polarizing film having a transmission axis in the width direction (manufactured by Sanlitz, HLC2-5618S, thickness 180 μm); 2. The stretched films of Comparative Examples 1, 2, and 4 were bonded together to obtain a long laminated film, and the circularly polarizing plate cut out from the laminated film was placed on the backlight side of a commercially available VA mode reflective liquid crystal display device. It replaced with the polarizing plate, it integrated so that the side which bonded the stretched film may be arrange | positioned at the liquid crystal cell side, and the display characteristic of the obtained liquid crystal display device was confirmed from the front visually.

  In addition, the long polarizing film whose transmission axis is in the width direction was cut into a predetermined size, and the stretched film of Examples 3 and 4 was cut into a predetermined size and obtained by bonding. The circularly polarizing plate was replaced with a polarizing plate on the backlight side of a commercially available VA mode reflective liquid crystal display device, and the side where the stretched film was bonded was placed so as to be disposed on the liquid crystal cell side. The display characteristics were confirmed from the front by visual observation.

(Production example)
A pellet of thermoplastic norbornene resin (Zeon Corporation, ZEONOR 1420, glass transition point 137 ° C.), which is a kind of alicyclic olefin polymer, was dried at 100 ° C. for 5 hours. The pellets were supplied to an extruder, melted in the extruder, passed through a polymer pipe and a polymer filter, extruded from a T-die onto a casting drum, cooled, and a transparent resin film 1 having a thickness of 160 μm was obtained.

Example 1
This transparent resin film 1 was obliquely stretched using the tenter stretching machine for oblique stretching as shown in FIG. 1 under the conditions shown in Table 1 to obtain a first stretched film a having an average orientation angle of 39 °. . (The feeding angle (the angle of the film feeding direction with respect to the film winding direction, hereinafter the same) was set to 39 °.) Next, the stretched film a was simultaneously biaxially stretched (simultaneously) under the conditions shown in Table 1. The biaxial stretching was performed by stretching the transparent resin film under such conditions that the slow axis appears in the longitudinal direction of the film. A 1340 mm stretched film (retardation film) A was obtained.

  A polarizing plate using the obtained retardation film A was incorporated in a VA mode liquid crystal display device A, and the display characteristics of the screen were evaluated. In addition, the polarizing plate was manufactured by laminating the retardation film A and a long polarizing film on a roll-to-roll basis.

  Table 1 shows the stretching conditions of the retardation film A. In Table 1, the stretching ratio in simultaneous biaxial stretching represents the film surface ratio (stretching ratio in the longitudinal direction of the film × stretching ratio in the width direction of the film). same as below. As shown in Tables 1 and 2, the evaluation results showed that the average Nz coefficient value was larger than 1.5, and the variation in the orientation angle and the Nz coefficient value could be reduced. The display color unevenness of the liquid crystal display device was not seen over the entire surface of the display image, and no change was seen in the display image even when the observation angle was changed.

(Example 2)
The transparent resin film 1 obtained in Production Example 1 was simultaneously biaxially stretched under the conditions shown in Table 1 to obtain a first stretched film (biaxially stretched film) b having an average orientation angle of 90 °. Next, the biaxially stretched film b was obliquely stretched under the conditions shown in Table 1 (note that the feed angle was set to 39 °), and then the film was trimmed at both ends in the same manner as in Example 1 to thereby stretch the stretched film. (Phase difference film) B was obtained. Further, a polarizing plate using the retardation film B was incorporated in the liquid crystal display device B, and the display characteristics were evaluated. In addition, the polarizing plate was manufactured by laminating the retardation film B and a long polarizing film on a roll-to-roll basis.

  Table 1 shows the stretching conditions of the retardation film B. As shown in Tables 1 and 2, the evaluation results showed that the average Nz coefficient value was larger than 1.5, and the variation in the orientation angle and the Nz coefficient value could be reduced. The display color unevenness of the liquid crystal display device was not seen over the entire surface of the display image, and no change was seen in the display image even when the observation angle was changed.

(Example 3)
A stretched film (retardation film) C was obtained in the same manner as in Example 1 except that the feeding angle was set to 11 °. Further, a polarizing plate using the retardation film C was incorporated in the liquid crystal display device C, and the display characteristics were evaluated. The polarizing plate is obtained by cutting the retardation film C into a predetermined size at a predetermined angle, and converting the polarizing film cut into a predetermined size into a polarizing transmission axis of the polarizing film and a retardation phase of the retardation film C. Lamination was performed such that the angle of intersection with the axis was 45 °.

  Table 1 shows the stretching conditions of the retardation film C. As shown in Tables 1 and 2, the evaluation results showed that the average Nz coefficient value was larger than 1.5, and the variation in the orientation angle and the Nz coefficient value could be reduced. The display unevenness of the liquid crystal display device was not observed over the entire surface of the display image, and even when the observation angle was changed, the display image was hardly changed.

Example 4
A retardation film D was obtained in the same manner as in Example 2 except that the feeding angle was set to 11 °. Furthermore, the polarizing plate using the stretched film (retardation film) D was incorporated in the liquid crystal display device D, and the display characteristics were evaluated. Note that the polarizing plate is obtained by cutting the retardation film D into a predetermined size at a predetermined angle, and converting the polarizing film cut into a predetermined size into a polarizing transmission axis of the polarizing film and a retardation phase of the retardation film D. Lamination was performed such that the angle of intersection with the axis was 45 °.

  Table 1 shows the stretching conditions of the retardation film D. As shown in Tables 1 and 2, the evaluation results showed that the average Nz coefficient value was larger than 1.5, and the variation in the orientation angle and the Nz coefficient value could be reduced. The display unevenness of the liquid crystal display device was not observed over the entire surface of the display image, and even when the observation angle was changed, the display image was hardly changed.

(Comparative Example 1)
The transparent resin film 1 obtained in Production Example 1 was obliquely stretched under the conditions shown in Table 1 to obtain a stretched film (retardation film) E having an average orientation angle of 45 ° (note that the feed angle is 45). Set to °). Further, a polarizing plate using the retardation film E was incorporated in the liquid crystal display device E to evaluate display characteristics.

  Table 1 shows the stretching conditions of the retardation film E. As shown in Tables 1 and 2, the evaluation results showed that the average Nz coefficient value was smaller than 1.5, and the variation in the orientation angle and the Nz coefficient value was also large. Color unevenness in the display of the liquid crystal display device is seen at the edge of the display image, and when the observation angle is changed, the entire display image is caused by variations in the average Nz coefficient value, the orientation angle, and the Nz coefficient value. There were significant changes throughout.

(Comparative Example 2)
A stretched film (retardation film) F was obtained in the same manner as in Example 1 except that the feeding angle was set to 3 °. Further, a polarizing plate using the retardation film F was incorporated in the liquid crystal display device F to evaluate display characteristics.

  Table 1 shows the stretching conditions of the retardation film F. As shown in Tables 1 and 2, the evaluation results showed large variations in the values of the orientation angle and the Nz coefficient. The color unevenness of the display of the liquid crystal display device is seen at the edge of the display image, and when the observation angle is changed, a large change is seen in the display image due to variations in the values of the orientation angle and the Nz coefficient. It was.

(Comparative Example 3)
The transparent resin film 1 obtained in Production Example 1 was stretched obliquely under the conditions shown in Table 1, but wrinkles were generated on the film and could not be wound. (The feed angle was set to 83 °.)
(Comparative Example 4)
A stretched film (retardation film) G was obtained in the same manner as in Example 2 except that simultaneous biaxial stretching was performed so that the average orientation angle was 0 ° and the feeding angle was set to 51 °. Further, a polarizing plate using the retardation film G was incorporated in the liquid crystal display device G, and the display characteristics were evaluated.

Table 1 shows the stretching conditions of the retardation film G. As shown in Tables 1 and 2, the evaluation results showed that the average Nz coefficient value was 1.5, but the orientation angle and the Nz coefficient value varied greatly. The color unevenness of the display of the liquid crystal display device was seen at the edge of the display image, and when the observation angle was changed, a slight change was seen in the display image.

2 ... Obliquely stretching tenter stretching machine, 4 ... Simultaneous biaxial stretching tenter stretching machine, 11 ... Transparent resin film (raw material), 13 ... First stretched film, 46 ... Second stretched film

Claims (7)

Made of transparent resin with positive intrinsic birefringence ,
A long stretched film having an average orientation angle θ in the range of 10 to 80 ° with respect to the width direction and an average Nz coefficient in the range of more than 2.0 and 10.0 or less . Stretched long film of claim 1 upper limit value of the average Nz coefficient of 3.0. The long stretched film according to claim 1 or 2, wherein the transparent resin having a positive intrinsic birefringence is an alicyclic olefin polymer. The long stretched film according to any one of claims 1 to 3, wherein the average orientation angle θ is in the range of 40 to 50 ° with respect to the width direction. The long stretched film according to any one of claims 1 to 4 ,
With a long polarizing film,
A long laminated film in which the longitudinal directions are aligned. A polarizing plate formed by cutting the long laminated film according to claim 5 into a predetermined size. A VA mode or OCB mode liquid crystal display device comprising the polarizing plate according to claim 6 .

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