JP2008268341A - Manufacturing method of optical film, optical film, and liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of an optical film that can prevent an influence on alignment of liquid crystal on a rubbing processing surface as much as possible by winding a long plastic film after rubbing processing, the optical film, and liquid crystal display device. <P>SOLUTION: A peeling film G is stuck onto the rubbing processing surface of the long plastic film F after the rubbing processing and before a stage of applying liquid crystal molecules. The peeling film G at this time has a projection portion formed of an adhesive tape G2 on the surface on the opposite side to the surface facing the rubbing processing surface. Then A stack H of the long plastic film F and peeling film G is wound to form a roll body H'. At this time, the stack H is wound in a state in which a projection portion of the peeling film G is abutted on the reverse surface (the surface on the opposite side to the rubbing processing surface) of the long plastic film F. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to a method for producing an optical film used for optical compensation and antireflection of a liquid crystal display device and the like, and an optical film and a liquid crystal display device obtained thereby, in particular, a step of winding a plastic film after rubbing treatment. The present invention relates to an optical film manufacturing method, an optical film obtained thereby, and a liquid crystal display device.

  Conventionally, various optical elements manufactured by applying and aligning a liquid crystal material on the surface of a substrate are known. In the manufacturing process of such an optical element, in order to align the liquid crystal material on the surface of the substrate, for example, a rubbing process is generally performed in which the substrate surface is rubbed in one direction with a raised cloth. For example, when the optical element is a liquid crystal cell, the rubbing process is performed on a glass substrate unit basis. However, in the case of an optical element (optical film) using a plastic film as a base material, it is continuous in a so-called roll-to-roll method using a long plastic film, rather than performing a rubbing process in units of cut films. The rubbing process is overwhelmingly advantageous in terms of manufacturing efficiency and cost.

  Therefore, when manufacturing an optical film, various methods have been conventionally proposed as methods for continuously rubbing a long plastic film by the roll-to-roll method as described above.

  For example, in Patent Document 1, a long plastic film is conveyed by a conveyor belt having a mirror-finished metal surface, and the film surface is rubbed with a rubbing roll disposed on the conveyor belt. A rubbing method characterized by the above has been proposed. As a base material to be rubbed, a material having a linear structure, for example, a triacetyl cellulose (TAC) film or a polyethylene terephthalate (PET) film is generally used.

  After such rubbing treatment, liquid crystalline molecules having one or more functional groups are made into a solution using an appropriate organic solvent, applied to the surface of the rubbing treated film, and then dried and oriented. Then, an optical film is manufactured by exposing to appropriate ultraviolet rays or the like to be crosslinked and fixed.

  Prior to the step of applying liquid crystal molecules to the rubbing surface as described above, it is also known to perform a process of laminating a release film to make the charge on the rubbing surface uniform (see, for example, Patent Document 2). ). By sticking such a release film, the charge on the rubbing surface becomes uniform, and the orientation of the liquid crystal applied to the rubbing surface is greatly improved.

On the other hand, in the manufacturing process of the optical film as described above, the series of processes may not be performed continuously due to equipment and time constraints. At this time, after laminating the release film on the rubbing treated surface after the rubbing treatment to form a laminate, the laminate is wound around an axis perpendicular to the transport direction to form a roll body and stored. Thus, the manufacturing process of the optical film is divided.
JP 2004-170454 A JP 2006-72298 A

  However, by winding the laminate as described above to form a roll body, stress is applied to the rubbing surface of the long plastic film. As a result, the charge on the rubbing surface is not uniformly charged, and there is a problem that the orientation of the liquid crystal is disturbed even when the release film is bonded.

  The present invention has been made to solve such problems of the prior art, and as much as possible the influence on the orientation of the liquid crystal on the rubbing treatment surface by winding a long plastic film after the rubbing treatment. It is an object of the present invention to provide a method for producing an optical film that can be prevented, and an optical film and a liquid crystal display device obtained thereby.

  In order to solve the above-mentioned problems, the method for producing an optical film according to the present invention includes a rubbing treatment step in which the surface of a long plastic film is rubbed with a rubbing roll having an axis of rotation inclined from a direction perpendicular to the plastic film conveying direction. Then, a release film having a convex portion on one surface is pasted on the rubbing-treated surface of the long plastic film so that the other surface of the release film faces the rubbing-treated surface. A step of forming a laminated body together, a step of winding the laminated body into a roll body, and a step of peeling the release film from the long plastic film after unwinding the laminated body from the roll body And a coating step of coating liquid crystal molecules on the rubbed surface of a long plastic film. And it is characterized in Rukoto.

According to the above invention, the release film is bonded to the rubbing treatment surface of the long plastic film after the rubbing treatment step and before the liquid crystal molecule coating step. The release film at this time has a convex portion on the surface opposite to the surface facing the rubbing surface. And the laminated body of a long plastic film and a peeling film is wound up, and a roll body is formed.
At this time, a laminated body is wound in the state which the convex part of the peeling film contact | abutted to the back surface (surface on the opposite side to a rubbing process surface) of a long plastic film.

  In this way, by providing a convex portion on the surface opposite to the surface facing the rubbing treatment surface of the release film, when the laminate is wound up, a portion of the release film having no convex portion is a long plastic. Contact with the back side of the film is prevented. As a result, the stress applied to the rubbing treatment surface due to winding is less likely to occur at locations where there are no protrusions. Therefore, it is possible to prevent as much as possible the influence on the orientation of the liquid crystal on the rubbing treatment surface by winding the long plastic film after the rubbing treatment.

Preferably, the convex part of the said peeling film is provided in the width direction both ends.
More preferably, the convex part of the said peeling film is formed with the adhesive tape affixed on the width direction both ends of the flat base film.

In this case, since the convex part of a peeling film is provided in the width direction both ends, it can make it hard to produce the stress to a rubbing process surface in the width direction center part of a elongate plastic film.
Therefore, the liquid crystal orientation in the central portion of the optical film can be improved, and the quality of the optical film can be further improved.

  Preferably, in the rubbing treatment step, a backup roll mechanism that supports and transports the long plastic film by a transport belt having a metal surface and supports the lower surface of the transport belt that supports the long plastic film. The backup roll mechanism is provided with a plurality of backup rolls that respectively rotate along the conveyance direction of the conveyance belt, and the plurality of backup rolls are directly below the rubbing roll and rotate the rubbing roll. It is disposed along a straight line substantially parallel to the axis.

In this case, since it is possible to continuously rub a long plastic film by a roll-to-roll method, it is possible to manufacture an optical film at low cost. In addition, when an alignment film is formed on the surface of the plastic film before the rubbing treatment, scratches are less likely to occur during film transportation, and foreign materials are less likely to adhere to the surface when the rubbing treatment is performed. It is possible to maintain the appearance of the film.
Further, the backup roll mechanism that supports the lower surface of the conveyance belt that supports the plastic film includes a plurality of backup rolls disposed directly along a straight line that is directly below the rubbing roll and substantially parallel to the rotation axis of the rubbing roll. Therefore, even if the rotating shaft of the rubbing roll is inclined from the direction perpendicular to the conveying direction of the conveying belt, each backup roll is disposed directly below the inclined rubbing roll via the plastic film and the conveying belt. It will be.
Furthermore, since each backup roll rotates along the conveyance direction of the conveyance belt (the conveyance direction of the plastic film), the rotation of each backup roll hinders the movement of the conveyance belt in the conveyance direction and consequently the conveyance of the plastic film. Nor.
Therefore, even if the pushing amount of the rubbing roll is increased while the rotation axis of the rubbing roll is inclined from the direction perpendicular to the conveying direction of the conveying belt, the flatness of the conveying belt is improved and the slack is not easily generated. The rubbing process can be performed in a stable state without hindering the movement of the belt. As a result, uniform orientation characteristics can be imparted to the plastic film, and as a result, an optical film having uniform optical characteristics can be manufactured.

  Preferably, the peeling force on the surface of the release film facing the rubbing-treated surface of the long plastic film is 0.5 N / 50 mm or less.

  The optical film according to the present invention is obtained by the above-described optical film manufacturing method. Moreover, the liquid crystal display device according to the present invention is characterized by having the optical film.

  According to the method for producing an optical film according to the present invention, by providing a convex portion on the surface opposite to the surface facing the rubbing treatment surface of the release film, when the laminate is wound, In the absence, contact with the back surface of the long plastic film is prevented. As a result, the stress applied to the rubbing treatment surface due to winding is less likely to occur at locations where there are no protrusions. Therefore, it is possible to prevent as much as possible the influence on the orientation of the liquid crystal on the rubbing treatment surface by winding the long plastic film after the rubbing treatment. Therefore, the quality of the optical film obtained by this and a liquid crystal display device provided with this can be kept high irrespective of a manufacturing process.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is a front view showing a schematic configuration of a rubbing treatment apparatus for performing a rubbing treatment step in the method for producing an optical film according to an embodiment of the present invention. 2 is a diagram showing a schematic configuration of the backup roll mechanism shown in FIG. 1. FIG. 2 (a) is a plan view, FIG. 2 (b) is a perspective view in the vicinity of the backup roll, and FIG. The figure seen from the conveyance direction of a film is shown, respectively. As shown in FIG. 1, the rubbing processing apparatus 100 according to the present embodiment has an endless track that is installed between the drive rolls 1 and 2 and the drive rolls 1 and 2 and supports and transports a long plastic film F. A conveyance belt 3, a rubbing roll 4 disposed above and below the conveyance belt 3 so as to be movable up and down, and a backup roll mechanism 5 that supports the lower surface of the conveyance belt 3 that supports the plastic film F are provided. In addition, before and after the rubbing apparatus 100, an appropriate static eliminator or dust remover may be installed as necessary.

  The conveyor belt 3 is a metal surface (the entire conveyor belt 3 may be made of metal) having a mirror-finished surface on the side that supports the long plastic film F. As such a metal, various metal materials such as copper and steel can be used, but stainless steel is preferably used in terms of strength, hardness and durability. In order to ensure adhesion with the plastic film F, the surface finish (Ra) is preferably 0.02 μm or less, more preferably 0.01 μm or less as the degree of mirror finish. In order to prevent the plastic film F from slackening, it is necessary to prevent the conveyance belt 3 that supports the plastic film F from slackening. Considering that it is necessary to provide a certain degree of flexibility in order to prevent looseness of the conveyor belt 3 and to be installed between the drive rolls 1 and 2, the thickness of the conveyor belt 3 is 0.5 mm to 2 mm. The thickness is preferably 0 mm, more preferably 0.7 mm to 1.5 mm. In addition, the tension applied to the conveyor belt 3 is preferably 0.5 to 20 kgf / mm 2, more preferably, considering the tension strength of the conveyor belt 3 while preventing slack of the conveyor belt 3. 2 to 15 kg weight / mm 2.

  The rubbing roll 4 has a brushed cloth 4a wound around its outer peripheral surface. What is necessary is just to select suitably the material, shape, etc. of a raising cloth according to the material of the plastic film F to which the rubbing process is performed. In general, rayon, cotton, nylon, triacetate, or a mixture thereof can be applied as the raised cloth 4a. The rotation axis of the rubbing roll 4 according to this embodiment is inclined from a direction perpendicular to the transport direction of the plastic film F (the direction indicated by the arrow A in FIG. 1) (for example, the inclination angle exceeds 0 ° and is 45 ° or less). ), That is, an arbitrary axial angle with respect to the long side of the plastic film F can be set. Moreover, the rotation direction of the rubbing roll 4 can be appropriately selected according to the conditions of the rubbing treatment. The outer diameter of the rubbing roll 4 (including the raised cloth 4a) is preferably set to 130 mm to 170 mm (more preferably 140 mm to 160 mm).

  As shown in FIG. 2, the backup roll mechanism 5 includes a plurality of backup rolls 51 that respectively rotate along the conveyance direction of the conveyance belt 3 (the direction indicated by the arrow A in FIG. 2A). Each backup roll 51 is disposed directly below the rubbing roll 4 and along a straight line substantially parallel to the rotation axis of the rubbing roll 4.

  As described above, the backup roll mechanism 5 that supports the lower surface of the conveyance belt 3 that supports the plastic film F is disposed directly below the rubbing roll 4 and along a straight line that is substantially parallel to the rotation axis of the rubbing roll 4. Since the plurality of backup rolls 51 are provided, the rotation axis of the rubbing roll 4 is inclined from the direction perpendicular to the conveying direction of the conveying belt (for example, the straight line C1 in FIG. Even in the case of a shaft), each backup roll 51 is disposed directly under the inclined rubbing roll 4 via the plastic film F and the conveyor belt 3. Furthermore, since each backup roll 51 rotates along the conveyance direction of the conveyance belt 3 (the conveyance direction of the plastic film F), the rotation of each backup roll 51 moves in the conveyance direction of the conveyance belt 3 and consequently the plastic film F. There is no hindrance to the transport. Accordingly, even if the pushing amount of the rubbing roll 4 is increased in a state where the rotation axis of the rubbing roll 4 is inclined from a direction perpendicular to the conveying direction of the conveying belt 3, the flatness of the conveying belt 3 is improved and the slackness is increased. The rubbing process can be performed in a stable state without being easily generated and without disturbing the movement of the conveyor belt 3. As a result, uniform orientation characteristics can be imparted to the plastic film F, and as a result, an optical film having uniform optical characteristics can be manufactured.

  As a preferable configuration, the backup roll mechanism 5 according to the present embodiment is rotatable about a base portion 52 disposed along a straight line substantially parallel to the rotation axis of the rubbing roll 4 and the normal line of the surface of the conveyor belt 3. A plurality of support portions 53 pivotally supported on the pedestal portion 52 are further provided, and each backup roll 51 is pivotally supported by each support portion 53 so as to be rotatable along the transport direction of the transport belt 3. If it demonstrates more concretely, the support part 53 which concerns on this embodiment is pivotally supported by the base part 53 by the shaft member 54, and can be rotated around the shaft member 54. As shown in FIG. Further, the backup roll 51 according to the present embodiment is pivotally supported by the support portion 53 by the shaft member 55 and is rotatable around the shaft member 55.

  According to such a preferable configuration, even if the rotation axis of the rubbing roll 4 is inclined from the direction perpendicular to the conveyance direction of the conveyance belt 3 (the direction of the straight line C0 in FIG. 2A), the backup roll mechanism 5 is provided. By inclining the pedestal 52 in the same manner (that is, by tilting the pedestal 52 so as to follow a straight line substantially parallel to the rotation axis of the inclined rubbing roll), the movement of the conveyor belt 3 ( Support supported by the pedestal 52 so that the backup roll 51 supported by the support 53 is rotated along the direction of conveyance of the conveyance belt 3 (by a frictional force applied from the lower surface of the conveyance belt 3). The part 53 rotates naturally. In other words, the inclination angle of the rubbing roll 4 is not fixed as in the present embodiment, and even if the setting value of the inclination angle is changed, the pedestal 52 is only changed to the same inclination angle as the rubbing roll 4. Each of the backup rolls 51 can be disposed immediately below the rubbing roll 4 and can be rotated along the conveying direction of the conveying belt 3.

  Further, as shown in FIG. 2C, the backup roll mechanism 5 according to the present embodiment has a preferable configuration in which the rotation axis of the rubbing roll 4 is inclined from the direction perpendicular to the conveyance direction of the conveyance belt 3. In addition, a coupling mechanism 56 that couples the rubbing roll 4 and the pedestal portion 52 so as to incline the pedestal portion 52 accordingly. More specifically, the coupling mechanism 56 according to the present embodiment supports the rubbing roll 4 so as to be rotatable about the rotation axis and to be vertically movable, and to support the pedestal 52. The frame is shaped like a letter, and can be rotated in the direction of the arrow B in FIG. 2C by a motor M attached to the top of the frame. When the coupling mechanism 56 is rotated in the direction of arrow B in FIG. 2C by the motor M, the rubbing roll 4 and the pedestal 52 supported by the coupling mechanism 56 are rotated (inclined) by the same angle in the same direction. ). Therefore, setting becomes extremely easy as compared with the configuration in which the rubbing roll 4 and the pedestal portion 52 are individually inclined. In the present embodiment, the configuration in which the coupling mechanism 56 is automatically rotated using the motor M has been described. However, the present invention is not limited to this, and a configuration in which the coupling mechanism 56 is manually rotated is employed. Is also possible.

  In the present embodiment, as a preferred configuration, the distance L1 between the centers of adjacent backup rolls 51 in the rotation axis direction (see FIG. 2A) is 60 mm or more and 200 mm or less (more preferably, 70 mm or more and 150 mm or less). Set to Further, the width L2 (see FIG. 2A) of each backup roll 51 in the rotation axis direction is set to 20 mm or more and 150 mm or less (more preferably 25 mm or more and 70 mm or less). In addition, the separation distance L3 (see FIG. 2A) between the adjacent backup rolls 51 is 40 mm or more and 60 mm or less (more preferably 45 mm or more and 55 mm or less), and the outer diameter of each backup roll 51 is 70 mm or more and 110 mm or less ( More preferably, the length of the pedestal portion 52 is set to 1500 mm or more and 2500 mm or less (however, a value larger than the width of the conveyor belt 3).

  When the rubbing process is performed on the plastic film F using the rubbing apparatus 100 having the above-described configuration, the end of the long plastic film F wound around a predetermined roll (not shown) has a plurality of transports. It is supplied onto the conveyor belt 3 via a roll (not shown). Then, by driving the drive rolls 1 and 2 to rotate, the conveyance belt 3 moves in the direction indicated by the arrow C in FIG. 1, and accordingly, the plastic film F is also conveyed together with the conveyance belt 3 and rubbed by the rubbing roll 4. Processing will be performed.

  In addition, as the plastic film F to which the manufacturing method according to the present embodiment is applied, the surface was rubbed or the alignment film formed on the surface was rubbed to be applied to the surface as described later. As long as a function capable of aligning liquid crystal molecules is provided, the material is not particularly limited.

  For example, as the plastic film F, polyolefins such as triacetyl cellulose (TAC), polyethylene, polypropylene, poly (4-methylpentene-1), polyimide, polyimide amide, polyether imide, polyamide, polyether ether ketone, polyether Ketone, polyketone sulfide, polyethersulfone, polysulfone, polyphenylene sulfide, polyphenylene oxide, polyethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, polyacetal, polycarbonate, polyarylate, acrylic resin, polyvinyl alcohol, polypropylene, cellulose plastics, epoxy resin And a film made of a phenol resin or the like. However, the manufacturing method according to the present embodiment is particularly effective for a film that is susceptible to blocking, such as a triacetyl cellulose film.

  Examples of the alignment film formed on the surface of the plastic film F include polyvinyl alcohol, polyimide, and polyamide. Examples of the method for forming the alignment film include spin coating, bar coating, slot cost coating, and dip coating. Further, the thickness of the alignment film to be formed can be appropriately set according to the surface roughness of the plastic film F before the alignment film is formed, but is preferably 0.1 μm to 5 μm (more preferably The thickness is 0.2 μm or more and 3 μm or less, more preferably 0.3 μm or more and 1 μm or less.

  Further, if the surface roughness Rz of the plastic film F before the alignment film is formed is too small, scratches are likely to occur during film conveyance, whereas if it is too large, it is difficult to perform a rubbing treatment on the roughness protrusions. As a result, foreign substances are easily attached. Accordingly, the thickness is preferably 120 nm to 600 nm (more preferably 200 nm to 500 nm, still more preferably 300 nm to 450 nm). In addition, the surface roughness Rz in this invention means the maximum height prescribed | regulated by JIS B0601 of 2001 fiscal year.

  In general, the conveying speed of the plastic film F is 1 to 50 m / min, preferably 1 to 10 m / min, and the rotation speed of the rubbing roll 4 is 1 to 3000 rpm, Is in the range of 500 to 2000 rpm, and the pushing amount of the rubbing roll 4 is 100 to 2000 μm, preferably 100 to 1000 μm. The “pushing amount of the rubbing roll 4” means that when the position of the rubbing roll 4 is changed with respect to the surface of the plastic film F, the bristles of the raised cloth wound around the rubbing roll 4 are the plastic film first. The position in contact with the F surface is defined as the origin (0 point), which means the amount of pressing of the rubbing roll 4 from the origin toward the plastic film F (position variation).

After the rubbing treatment step as described above, in this embodiment, a release film having a convex portion on one surface on the surface of the plastic film F that has been subjected to the rubbing treatment (hereinafter referred to as a rubbing treatment surface). A step of forming a laminate H by bonding G so that the other surface of the release film G faces the rubbing treatment surface, and a step of winding the laminate H into a roll H ′ The process of peeling the release film G from the plastic film F is performed after the laminate H is unwound from the roll body H ′.
In this embodiment, as a more preferable aspect, it is comprised so that the convex part of the said peeling film G may be provided in the both ends of the width direction (direction orthogonal to the conveyance direction A). As a more preferred embodiment, the convex portions of the release film G are formed by an adhesive tape G2 attached to both ends in the width direction of the flat base film G1.

FIG. 3 is a conceptual perspective view showing a winding mechanism used in the laminated body forming step and the roll body forming step in the present embodiment.
The take-up mechanism 6 is disposed on the conveyor belt 3 and downstream of the backup roll mechanism 5 in the conveyance direction. Between the winding mechanism 6 and the backup roll mechanism 5, a base film forming mechanism (not shown) for forming the base film G1 on the rubbing treated surface of the plastic film F that has been subjected to the rubbing treatment is disposed. Is done.

  First, the release film G is bonded to the rubbing treated surface of the plastic film F by the base film forming mechanism and the winding mechanism 6. In the present embodiment, first, a flat base film G1 is formed on the rubbing treated surface of the plastic film F.

  The base film G1 includes a base layer and an adhesive layer so that the base film G1 can be attached to and peeled from the plastic film F. Although the manufacturing method in particular of base film G1 is not restrict | limited, It is preferable to form into a film by a co-extrusion method with a base material layer and an adhesion layer. The coextrusion method can be carried out according to an inflation method, a T-die method or the like generally used for film production. As another manufacturing method, a method of forming the base film G1 by a method of coating and forming an adhesive layer on the base material layer, or the like can be adopted.

  Examples of the material for forming the base material layer include olefin resins. Olefin-based resins are copolymer resins such as block polymers and random polymers that use olefin homopolymers, multiple olefins, and other monomers, such as propylene-based polymers, low-density polyethylene, Density polyethylene, medium density polyethylene, linear low density, etc. ethylene polymer, ethylene / propylene copolymer, ethylene-α-olefin copolymer, olefin polymer such as reactor TPO, ethylene / methyl methacrylate copolymer, etc. Examples are olefinic copolymers of olefins and other monomers.

  For the purpose of preventing deterioration or the like, a light stabilizer such as an antioxidant, an ultraviolet absorber, or a hindered amine light stabilizer may be added to the base material layer. In addition, an antistatic agent and other suitable additives such as fillers such as calcium oxide, magnesium oxide, silica, zinc oxide, and titanium oxide, pigments, anti-tarnish agents, lubricants, antiblocking agents, and the like can also be blended.

  Although the thickness of a base material layer is 20-300 micrometers, Preferably it is 30-250 micrometers, More preferably, it is 40-200 micrometers, but it is not limited to this.

  As the resin for forming the adhesive layer, an ethylene / vinyl acetate copolymer is suitable. In addition, as a material constituting the adhesive layer, for example, a known adhesive such as rubber, acrylic or urethane can be used. Examples of rubber-based polymers include diene polymers such as natural rubber, polyisobutylene, butyl rubber, polyisoprene, polybutadiene and their hydrogenated products, ethylene propylene rubber, ethylene-α-olefin, ethylene-propylene-α-olefin, and propylene. -Olefin-based rubbers such as α-olefin, styrene-butadiene-styrene (SBS), styrene-isoprene-styrene (SIS), styrene-ethylene-butylene-styrene (SEBS), styrene-ethylene-propylene-styrene (SEPS) ABA type block polymer such as styrene / butadiene (SB), styrene / isoprene (SI), styrene / ethylene / butylene copolymer (SEB), styrene / ethylene / propylene copolymer (SEP), etc. A-B type Copolymer, styrene random copolymer such as styrene / butadiene rubber (SBR), hydrogenated styrene random copolymer (HSBR), styrene / ethylene-butylene copolymer / AB, such as olefin crystal (SEBC) Examples include O-type styrene / olefin crystal block polymers, olefin crystals / ethylene-butylene copolymers / C / B / C type olefin crystal block polymers such as olefin crystals (CEBC), and the like. .

  When forming the adhesive layer, for example, softening agent, olefin resin, silicone polymer, liquid acrylic copolymer, phosphate ester compound, tackifier, anti-aging, etc. An appropriate additive such as a filler, a pigment such as an agent, a hindered amine light stabilizer, an ultraviolet absorber, and other calcium oxide, magnesium oxide, silica, zinc oxide, titanium oxide, and the like can be blended.

  The thickness of the pressure-sensitive adhesive layer may be appropriately determined according to the peeling force and the like, and is generally 1 to 50 μm, preferably 2 to 40 μm, particularly preferably 5 to 20 μm. If necessary, the adhesive layer may be protected by temporarily attaching a separator or the like until practical use.

  The base film G1 is bonded to the rubbing treatment surface of the plastic film F, but it is preferable that the rubbing treatment step is performed immediately after the rubbing treatment step so that the rubbing treatment surface is not contaminated. .

  Thus, after bonding the base film G1 to the plastic film F, the adhesive tape G2 used as the convex part of the peeling film G is affixed on the surface of the both ends of the width direction of the base film G1.

  Examples of the adhesive tape G2 include, but are not limited to, a known OPP tape (biaxially stretched polypropylene tape).

In this embodiment, as shown in FIG. 3, both ends of the plastic film F in the width direction (direction substantially perpendicular to the transport direction A) on the transport belt 3 that transports the plastic film F to which the base film G1 is bonded. An adhesive tape feeding shaft 61 that has an axis substantially perpendicular to the conveyance direction A and feeds the adhesive tape G2 to the surfaces of both end portions in the width direction of the base film G1 is disposed in the part. A plastic film F on which the base film G1 is bonded in a state where the tip of the adhesive tape G2 fed out from the adhesive tape feeding shaft 61 is stuck to the downstream end in the transport direction A on the surface of the base film G1. The adhesive tape G2 is stuck to the width direction both ends of the base film G1. A known slitter can be applied as an apparatus for realizing this. In the present embodiment, the adhesive tape G2 is continuously attached along the conveyance direction A, but may be attached at intervals of a predetermined pitch in the conveyance direction A.
Thus, the laminate film H is formed by forming the release film G having convex portions at both ends in the width direction on the rubbing treatment surface of the plastic film F by the base film G1 and the adhesive tape G2 adhered to the surface thereof. It is formed.
In the present embodiment, the release film G having convex portions is formed by sticking the adhesive tape G2 to the base film G1, but the present invention is not limited thereto. It is good also as integrally forming the film thicker than the direction center part.

Thereafter, the laminate H is wound up and formed into a roll body H ′.
In the present embodiment, as shown in FIG. 3, the laminate H is wound around an axis in a direction substantially orthogonal to the transport direction A, further downstream from the adhesive tape feeding shaft 61 in the transport direction A. A roll body rotation shaft 62 is disposed, and the laminate H is wound around the roll body rotation shaft 62. Since roll body H 'obtained by winding up the laminated body H can be removed from the optical film production line and stored, the optical film production process can be temporarily interrupted there.

FIG. 4 is a cross-sectional view including a roll body rotation axis of the roll body wound up in the present embodiment.
In the roll body H ′ formed by winding the laminated body H, the convex portion (adhesive film G2) of the release film G abuts on the back surface (the surface opposite to the rubbing surface) of the plastic film F. It becomes a state and the space part J is formed in the part without the convex part of the peeling film G.

In this embodiment, as shown in FIG. 3 and FIG. 4, the film is wound so that the convex part of the release film G is on the inside, but the structure is wound so that the convex part is on the outside. Also good.
However, since the space portion J is provided on all surfaces of the plastic film F by winding the convex portion so as to be inside, the influence on the orientation of the liquid crystal on the rubbing treatment surface of the plastic film F. It is possible to widen the range that can be prevented.

  Thus, by providing a convex portion on the surface opposite to the surface facing the rubbing treatment surface of the release film G, when the laminate H is wound up, Contact with the back surface of the plastic film F is prevented.

As a result, the stress applied to the rubbing treatment surface due to winding is less likely to occur at locations where there are no protrusions. In other words, the stress caused by winding the laminate H is diffused in the longitudinal direction of the laminate H by the space J.
Therefore, even when the long plastic film F after the rubbing treatment is temporarily wound up and stored, the influence of the winding on the orientation of the liquid crystal on the rubbing treatment surface can be prevented as much as possible. .

In this embodiment, since the convex part of the peeling film G is provided in the width direction both ends, it can be made hard to produce the stress to a rubbing process surface in the width direction center part of the elongate plastic film F. FIG.
Therefore, the liquid crystal orientation in the central portion of the optical film can be improved, and the quality of the optical film can be further improved.

  When the manufacturing process of the optical film is resumed, the laminate H is fed out from the roll body H ′, and the release film G (the base film G1 and the adhesive tape G2) is released from the plastic film F. In this embodiment, the base film G1 to which the adhesive tape G2 is attached is peeled from the plastic film F together with the adhesive tape G2.

  The release film G is preferably peeled off immediately before application of liquid crystal molecules to be described later so that the rubbing surface of the plastic film F is not contaminated. Although the peeling method of the peeling film G is not specifically limited, It is preferable to peel at a constant speed so as not to impair the orientation of the rubbing treatment surface. For example, it is preferably performed at 180 ° peel.

  At this time, it is preferable that the peeling force on the surface of the release film G facing the rubbing treatment surface of the plastic film F is 0.5 N / 50 mm or less. Thereby, the rubbing process surface of the plastic film F after peeling the peeling film G can be uniformly charged to either positive or negative charge.

  Liquid crystal molecules are applied to the rubbing-treated surface of the plastic film F that has been drawn out again as described above, and an optical film is manufactured by curing or solidifying the applied liquid crystal molecules.

  When applying liquid crystal molecules, a solution in which a liquid crystal compound is dissolved is generally used. As the liquid crystal molecules contained in the solution, a liquid crystal polymer, a liquid crystal prepolymer, a liquid crystal monomer, or the like is appropriately used.

  In the case of using a liquid crystal polymer, after the liquid crystal polymer solution is applied to the rubbing treated surface of the plastic film F, it is heated until it reaches the temperature range showing the liquid crystal phase, dried, and then brought to the room temperature while maintaining the liquid crystal phase. By rapidly cooling, a liquid crystal state exhibiting optical anisotropy can be fixed.

  When using a liquid crystal prepolymer or a liquid crystal monomer, these solutions are applied to the rubbed surface of the plastic film F, then heated to a temperature range higher than the liquid crystal phase, dried, and then in a state showing the liquid crystal phase. It is possible to fix the liquid crystal state exhibiting optical anisotropy by cooling to a temperature and crosslinking by exposing to ultraviolet rays or the like.

As the liquid crystal monomer, for example, a monomer represented by any of the following chemical formulas (1) to (16) can be selected.

  The liquid crystal monomer solution preferably contains a polymerization agent and a crosslinking agent. These polymerizing agent and crosslinking agent are not particularly limited, and for example, the following can be used. Examples of the polymerization agent include benzoyl peroxide (BPO) and azobisisobutyronitrile (AIBN). Examples of the crosslinking agent include isocyanate crosslinking agents, epoxy crosslinking agents, and metal chelate crosslinking. An agent can be used. Any one of these may be used, or two or more may be used in combination.

  The liquid crystal monomer solution coating liquid can be prepared, for example, by dissolving and dispersing the liquid crystal monomer in an appropriate solvent. Examples of the solvent include, but are not limited to, for example, halogenated hydrocarbons such as chloroform, dichloromethane, carbon tetrachloride, dichloroethane, tetrachloroethane, methylene chloride, trichloroethylene, tetrachloroethylene, chlorobenzene, and orthodichlorobenzene, phenol, p- Phenols such as chlorophenol, o-chlorophenol, m-cresol, o-cresol, p-cresol, aromatic hydrocarbons such as benzene, toluene, xylene, methoxybenzene, 1,2-dimethoxybenzene, acetone, methyl ethyl ketone (MEK), ketone solvents such as methyl isobutyl ketone, cyclohexanone, cyclopentanone, 2-pyrrolidone and N-methyl-2-pyrrolidone, and esters such as ethyl acetate and butyl acetate Solvent, alcohol solvent such as t-butyl alcohol, glycerin, ethylene glycol, triethylene glycol, ethylene glycol monomethyl ether, diethylene glycol dimethyl ether, propylene glycol, dipropylene glycol, 2-methyl-2,4-pentanediol, dimethylformamide Amide solvents such as dimethylacetamide, nitrile solvents such as acetonitrile and butyronitrile, ether solvents such as diethyl ether, dibutyl ether, tetrahydrofuran and dioxane, or carbon disulfide, ethyl cellosolve, butyl cellosolve, etc. Can be used. Among these, toluene, xylene, mesitylene, MEK, methyl isobutyl ketone, cyclohexanone, ethyl cellosolve, butyl cellosolve, ethyl acetate, butyl acetate, propyl acetate, and ethyl acetate cellosolve are preferable. These solvents may be, for example, one kind or a mixture of two or more kinds.

  The coating liquid may be flow-deployed by a conventionally known method such as a roll coating method, a spin coating method, a wire bar coating method, a dip coating method, an extrusion method, a curtain coating method, a spray coating method, Of these, spin coating and extrusion coating are preferred from the viewpoint of coating efficiency.

  The temperature condition of the heat treatment after applying the coating liquid of the liquid crystal monomer solution to the rubbing treated surface of the plastic film F depends on, for example, the type of liquid crystal monomer used, specifically the temperature at which the liquid crystal monomer exhibits liquid crystallinity. Although it can determine suitably, it is the range of 40-120 degreeC normally, Preferably it is the range of 50-100 degreeC, More preferably, it is the range of 60-90 degreeC. If the temperature is 40 ° C. or higher, the liquid crystal monomer can usually be sufficiently aligned, and if the temperature is 120 ° C. or lower, for example, the choice of the plastic film F is widened in terms of heat resistance. .

  The liquid crystal compound to be dissolved is not particularly limited as long as it can be applied. For example, a rod-like liquid crystal compound, a plate-like liquid crystal compound, or a polymer thereof is used. More specifically, azomethines, azoxys, cyanobiphenyls, cyanophenyl esters, benzoic acid esters, cyclohexanecarboxylic acid phenyl esters, cyanophenylcyclohexanes, cyano-substituted phenylpyrimidines, alkoxy-substituted phenylpyrimidines, Liquid crystal compounds such as phenyldioxanes, tolanes, alkenylcyclohexylbenzonitriles, and polymers thereof are preferably used.

  The optical film manufactured by the manufacturing method according to the present embodiment described above can be provided with functions such as phase difference, color compensation, viewing angle expansion, and antireflection by appropriately applying known methods. It can be used as an optical film for various display devices such as a liquid crystal display, a plasma display, and an EL display.

  Hereinafter, the features of the present invention will be further clarified by showing examples and comparative examples.

<Example 1>
(1) Rubbing treatment For a film in which an easy-adhesion polyethylene terephthalate (PET) film subjected to a hydrophilic treatment is used as a plastic film F, and a polyvinyl alcohol (PVA) having a thickness of 2.5 μm is formed as an alignment film on the surface. The rubbing treatment was performed using the rubbing treatment apparatus 100 shown in FIGS.
The mirror finish on the surface of the transport belt 3 is Ra = 0.01 μm, the outer diameters of the drive rolls 1 and 2 are 550 mm, the transport speed of the film is 5 m / min, and the outer diameters of the backup rolls 51 are all 90 mm. The center-to-center distance L1 in the rotation axis direction of the backup roll 51 is all 80 mm, and the width L2 in the rotation axis direction of each backup roll 51 is all 30 mm. The radius of the rubbing roll 4 (including the raised cloth 4a) was 76.89 mm, and a roll of a rayon raised cloth was used. The rotation axis of the rubbing roll 4 is inclined by 45 ° from the direction perpendicular to the film transport direction A, and each backup roll 51 is arranged directly below the rubbing roll 4 and along a straight line parallel to the rotation axis. . The number of rotations of the rubbing roll 4 was 1500 rpm, and the pushing amount was 0.4 mm. For measuring the thickness of the alignment film, a spectrophotometer: MCPD2000 manufactured by Otsuka Electronics was used. The same applies to Example 2 and Comparative Examples 1 and 2 described later.

  After the rubbing treatment, a base film G1 (manufactured by Sanitect: PAC-3) having a thickness of 60 μm is bonded to the rubbing treatment surface of the plastic film F, and the thickness is 50 μm at both ends in the width direction of the base film G1. A laminated body H was formed by sticking an adhesive tape G2 having a width of 50 mm (manufactured by Nitto Denko: trade name “Damplon Tape (NO.3200)”). Then, the laminated body H was used as a winding roll body H ′.

(2) Production of optical film 10 g of a polymerizable liquid crystal compound (BASF: trade name “Paliocolor LC242”) showing a nematic liquid crystal layer and a photopolymerization initiator for the polymerizable liquid crystal compound (Ciba Specialty Chemicals: trade name) “Irgacure 907”) 0.5 g and a leveling agent 0.06 g were dissolved in 40 g of cyclopentanone to prepare a liquid crystal composition (coating liquid).

Then, the above-mentioned roll body H ′ is fed out again, the release film G (base film G1 and adhesive tape G2) is peeled off, and the above coating liquid is applied to the rubbing treated surface of the plastic film F with a bar coater. Worked. Thereafter, the liquid crystal was aligned by heating and drying at 90 ° C. for 2 minutes.
A positive uniaxial film having a refractive index characteristic of nx> ny = nz by irradiating the liquid crystal layer thus formed with 20 mJ / cm ² of light using a metal halide lamp and curing the liquid crystal layer. An optical film (retardation plate) to be an optical compensation layer (coating A plate) was formed. The thickness of the optical compensation layer and the in-plane retardation value are adjusted by changing the coating amount of the coating liquid, the thickness is 1.4 μm, and the target in-plane retardation value Re [590] is 140 nm. did. From ny = nz, the thickness direction retardation value Rth [590] is also 140 nm.
Re [590] is an in-plane retardation value of the optical compensation layer measured with light having a wavelength of 590 nm at 23 ° C. (= (nx−ny) × d (d: thickness of the optical compensation layer (nm))) Means. Rth [590] is a retardation value in the thickness direction of the optical compensation layer measured with light having a wavelength of 590 nm at 23 ° C. (= (nx−nz) × d (d: thickness of the optical compensation layer (nm))) Means.

<Example 2>
An optical film was produced according to Example 1 except that a saponified triacetyl cellulose (TAC) film was used as the plastic film F.

<Comparative Example 1>
An optical film was produced according to Example 1 except that the roll body H ′ was formed without adhering the adhesive tape G2.

<Comparative example 2>
An optical film was prepared according to Example 2 except that the roll body H ′ was formed without attaching the adhesive tape G2.

ただし、ｘ_ｉ：幅方向ｉ番目の位相差値とする。
このδ（Δｎｄ）の値が小さいほどムラが少ない（目標とする面内位相差値Ｒｅ［５９０］＝１４０ｎｍとのずれが少ない）と評価することができる。 <Evaluation results>
(1) Evaluation of unevenness level For the optical films according to Examples and Comparative Examples, the phase difference between two points in the width direction was measured over a thickness of 1000 mm at a 1 mm pitch. For this measurement, RETS-1200VA manufactured by Otsuka Electronics was used. Then, an average value δ (Δnd) of the difference in phase difference was calculated from the difference between adjacent phase differences from the measured value and evaluated.
That is,

Where x _{i is the} i-th phase difference value in the width direction.
It can be evaluated that the smaller the value of δ (Δnd) is, the smaller the unevenness is (the smaller the deviation from the target in-plane retardation value Re [590] = 140 nm is).

(2) Contrast evaluation The optical films according to the examples and comparative examples were mounted on a Sony product: “PlayStation Portable (PSP)” liquid crystal cell, and black luminance and white luminance were measured using a Topcon BM5. Above, the contrast ratio was calculated and evaluated.
FIG. 5 is a side conceptual view showing the mounting state of the optical film used in the contrast evaluation in this example.

First, negative C plates were attached to both surfaces of the liquid crystal cell via an acrylic adhesive having a thickness of 20 μm.
The negative C plate was produced as follows.

That is, 90 parts by weight of a polymerizable liquid crystal material (liquid crystal monomer) exhibiting a nematic liquid crystal layer phase (BASF: trade name “Paliocolor LC242”), 10 parts by weight of chiral agent (BASF: trade name “Paliocolor LC756”), photopolymerization 5 parts by weight of an initiator (manufactured by Ciba Specialty Chemicals: trade name “Irgacure 907”) and 300 parts by weight of methyl ethyl ketone were uniformly mixed to prepare a coating liquid containing a liquid crystal composition. The coating liquid containing the liquid crystal composition was coated on a substrate (biaxially stretched PET film) using a spin coating method. Then, after heat-treating at 80 ° C. for 3 minutes, polymerization was performed by irradiating with ultraviolet rays (20 mJ / cm ² , wavelength 365 nm), and a long negative C plate having a refractive index distribution of nx = ny> nz (cholesteric orientation) A solidified layer) was formed on the substrate. The thickness of the negative C plate was 2.0 μm, the in-plane retardation value Re [590] was 0 nm, and the thickness direction retardation value Rth [590] was 120 nm.
Re [590] is the in-plane retardation value of the negative C plate measured with light having a wavelength of 590 nm at 23 ° C. (= (nx−ny) × d (d: thickness of the negative C plate (nm))) Means. Rth [590] is a retardation value in the thickness direction of the negative C plate measured with light having a wavelength of 590 nm at 23 ° C. (= (nx−nz) × d (d: thickness of the negative C plate (nm))) Means.

  After attaching such a negative C plate, the optical film (coating A plate) is attached to the surface of the negative C plate opposite to the liquid crystal cell attachment surface via an acrylic adhesive having a thickness of 12 μm. Were attached to each.

  Furthermore, a polarizing plate (TEG5465DU) made by Nitto Denko was attached to the surface opposite to the negative C plate attachment surface of the attached optical film with an acrylic adhesive having a thickness of 12 μm, to obtain an optical element. Formed.

  At this time, if the axial angle with respect to the absorption axis of the polarizing plate on one side of the optical element is 0 °, the axial angle with respect to the slow axis of the optical film (coating A plate) on the one side is 45 °. Yes, the axis angle about the absorption axis of the polarizing plate on the other side was 90 °, and the axis angle about the slow axis of the optical film on the other side was 135 °, respectively.

The evaluation results are shown in Table 1.

  As shown in Table 1, in the optical films according to Comparative Examples 1 and 2, the unevenness level is δ (Δnd) = 0.50 nm or more, while the contrast after mounting the liquid crystal cell is less than 600, and there is a problem at the practical level. there were. On the other hand, the optical films according to Examples 1 and 2 had a non-uniformity level of less than 0.50 nm, while the contrast after mounting the PSP cell was 600 or more, resulting in no problem at a practical level.

FIG. 1 is a front view showing a schematic configuration of a rubbing treatment apparatus for performing a rubbing treatment step in the method for producing an optical film according to an embodiment of the present invention. 2 is a diagram showing a schematic configuration of the backup roll mechanism shown in FIG. 1. FIG. 2 (a) is a plan view, FIG. 2 (b) is a perspective view in the vicinity of the backup roll, and FIG. The figure seen from the conveyance direction of a film is shown, respectively. FIG. 3 is a conceptual perspective view showing a winding mechanism used in the laminated body forming step and the roll body forming step in the present embodiment. FIG. 4 is a cross-sectional view including a roll body rotation axis of the roll body wound up in the present embodiment. FIG. 5 is a side conceptual view showing the mounting state of the optical film used in the contrast evaluation in this example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 5 ... Backup roll mechanism 51 ... Backup roll 52 ... Base part 53 ... Support part 56 ... Connection mechanism 6 ... Winding mechanism 100 ... Rubbing apparatus A ... Conveying direction F ... Plastic film G ... Release film G1 ... Base film G2 ... Adhesion Tape H ... Laminated body H '... Roll body

Claims (7)

A rubbing treatment step in which the surface of the long plastic film is rubbed by a rubbing roll having a rotation axis inclined from a direction perpendicular to the plastic film conveyance direction;
Affixed to the rubbing-treated surface of the long plastic film with a release film having a convex portion on one side so that the other side of the release film faces the rubbed surface Forming a laminate;
Winding the laminate into a roll, and
After unwinding the laminate from the roll body, peeling the release film from the long plastic film;
And a coating step of coating liquid crystal molecules on the rubbing-treated surface of a long plastic film.   The method for producing an optical film according to claim 1, wherein the protrusions of the release film are provided at both ends in the width direction.   The method for producing an optical film according to claim 2, wherein the protrusions of the release film are formed by an adhesive tape attached to both ends in the width direction of the flat base film. In the rubbing process, the long plastic film is supported and transported by a transport belt having a metal surface, and a backup roll mechanism is provided for supporting the lower surface of the transport belt that supports the long plastic film. ,
The backup roll mechanism includes a plurality of backup rolls that respectively rotate along the conveyance direction of the conveyance belt, and the plurality of backup rolls are directly below the rubbing roll and substantially parallel to the rotation axis of the rubbing roll. The method for producing an optical film according to claim 1, wherein the optical film is disposed along a straight line.   The optical force according to any one of claims 1 to 4, wherein a peeling force on the surface of the release film facing the rubbing-treated surface of the long plastic film is 0.5 N / 50 mm or less. A method for producing a film.   An optical film obtained by the method for producing an optical film according to claim 1.   A liquid crystal display device comprising the optical film according to claim 6.

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