TW201720739A - Production method of film roll an optic film is wound around a winding core while oscillating in a width direction relative to the winding core - Google Patents

Abstract

The present invention relates to a production method of a film roll, where the production method of a film roll includes an oscillation winding operation, wherein an optic film (F) is wound around a winding core while oscillating in a width direction relative to the winding core. A pitch of convex potions in the width direction of the optical film (F) is set as P (mm), where 13mm <=P<=40mm. The optic film (F) is wound in a manner of oscillating relative to the winding core by satisfying the condition that A>P among layers adjacent to each other in a lamination direction for the oscillation winding operation, where the same cross section includes the width direction of each layer of the optic film (F) laminated through winding, A is a misalignment amount in a width direction of oscillation between layers adjacent to each other in the lamination direction.

Description

Film roll manufacturing method

The present invention relates to a method of producing a film roll in which an optical film is wound (wobbled) in a width direction and wound around a core to produce a roll-shaped optical film.

At present, there is an increasing demand for thinning of an optical film used for a protective film of a polarizing plate or the like. When the optical film is formed into a film, winding defects are likely to occur when the optical film after film formation is wound. Therefore, proposals have been made from the past to improve the winding quality of various optical films.

For example, in Patent Document 1, the side edges of the optical film are aligned, and after the optical film is wound around the flat roll of the winding core, the optical film or the core is periodically vibrated in the width direction of the optical film. At the same time, when the optical film is wound around the wrap of the winding core, the film roll is formed such that no edge wave is generated or the winding is offset from the winding.

However, the above-mentioned edge wave refers to an embossing which is formed by the embossing of the optical film by the end portions (ear portions) of the optical film, and is collapsed by the winding of the optical film, and the ear is stretched. The phenomenon in the width direction. In addition, the above-mentioned winding offset refers to the case when the film roll is conveyed. Vibration, etc., without changing the desired shape of the wrap (roll shape).

Further, for example, in Patent Document 2, when the optical film is wound around the winding core, the vibration (wobble) in the winding direction is close to the core side in the direction perpendicular to the winding core (the thickness direction of the film roll). The period of the cycle is smaller than the far side, or the amplitude of the swing is either large, or both sides are oscillated. As a result, the reduction is called the agglomeration or the black strip (poor black belt), and the offset is both.

[Previous Technical Literature] [Patent Literature]

[Patent Document 1] Japanese Laid-Open Patent Publication No. 2010-150041 (Patent Application No. 1, Paragraph [0003], [0007], [0008], [0014], FIG. 1 and the like)

[Patent Document 2] Japanese Laid-Open Patent Publication No. 2013-100146 (Patent Application No. 1, Paragraph [0009], [0040], [0041], FIG. 2, etc.)

However, in the winding methods of Patent Documents 1 and 2, it is known that a polarizing plate is produced by feeding an optical film from a film roll, and when the produced polarizing plate is applied to a display device (for example, a liquid crystal display device), display unevenness occurs. By. The result of the investigation will be a long-form optical film in a film roll In the state where the film is stored in a high-temperature and high-humidity environment, where the film adheres to each other and where it is not attached, the phase difference is changed in the attached portion (for example, the thickness direction) Delayed Rth change), and in the unattached place, the result of phase difference variation is not caused, and it is clearly known that there is display unevenness.

Further, even if the wrap is wound, the film adhered to the film roll is attached to the surface of the film formed, and a plurality of irregularities are present in the width direction, and the width direction of the optical film is considered. In the gap of the convex portion, the amount of shift (swing amount) of each layer in the width direction of the swing is not appropriately set, and it is understood that the effect of preventing the sticking by the swing is not sufficiently exerted.

However, the concave portion and the convex portion arranged in the width direction of the optical film are formed in accordance with the position of each of the heat bolts when the optical film is formed by the solvent flow plastic film forming method. The above-mentioned thermal bolt is used in a flow molding die in which a flow-molding dopant is supported on a support, in order to adjust the length of the dopant flow direction (the direction in which the support moves) of the slit which is the outlet of the dopant ( The gap gap is set at a specific interval in the width direction. When the gap gap of the flow molding die is adjusted by thermally expanding and contracting the respective heat bolts, the amount of the dopant fluid-molded on the support is adjusted, whereby the thickness of the optical film to be formed can be adjusted. At this time, since the heat bolts are distributed in the width direction, the amount of adjustment of the gap gap is uneven due to the position in the width direction of the slit. Therefore, the thickness unevenness of the dopant which is flow molded on the support is generated in the width direction, and the thickness of the optical film of the formed film is uneven. However, even if the film is made of light In the case where the film is stretched horizontally (for the extension in the width direction), the optical film is horizontally stretched while maintaining the thickness unevenness in the width direction, and the thickness unevenness (surface unevenness) corresponding to the position of each heat bolt is It is produced in the width direction of the optical film.

Accordingly, in order to suppress the adhesion of the film of the film roll in a high-temperature and high-humidity environment, in order to suppress the display unevenness described above, the distance between the convex portions in the width direction of the optical film is considered, and the volume is appropriately rolled. By winding the optical film, it is necessary to sufficiently exhibit the effect of preventing the attachment via the swing. However, in the past, there has been no review of such swings.

The present invention has been made in order to solve the above-described problems, and an object of the invention is to provide a wobble through the optical film by an appropriate amount of swing in consideration of the distance between the convex portions in the width direction of the optical film. In this way, the method of manufacturing the film roll in which the optical films of the film roll in the high-temperature and high-humidity environment are adhered to each other can be suppressed.

The above object of the present invention is achieved by the following production method. That is, the method for producing a film roll according to one aspect of the present invention is a method for producing a film roll of a film roll by winding an optical film on a winding core, wherein the optical film is relatively opposite to the winding core And swinging in the width direction, having a swing winding process wound around the winding core, and the optical film is in the width direction, and has a plurality When the distance between the convex portions in the width direction of the optical film is P (mm), the surface of the optical film is 13 mm ≦ P ≦ 40 mm, and the layers of the optical film laminated by winding are included. In the same cross section in the width direction, when the amount of shift in the width direction between the layers adjacent to the stacking direction is set to A (mm), in the swing winding project, adjacent to the stacking direction Between each of the layers, A>P is satisfied, and the optical film is wound in a relative manner with respect to the winding core.

According to the above-described manufacturing method, in consideration of the distance P between the convex portions in the width direction of the optical film, the amount of shift A (the amount of swing) in the width direction of the respective layers laminated by the winding of the optical film is set. Further, the optical film is wound and wound in a direction that satisfies A>P between the layers adjacent to the lamination direction. Thereby, the effect of the adhesion prevention by the swing can be sufficiently exhibited, and even if the film roll is stored in a high-temperature and high-humidity environment, the adhering of the optical films can be suppressed.

41‧‧‧Volume core

A‧‧‧ offset

F‧‧‧Optical film

H1, H2, H3‧‧‧ convex

P‧‧‧ spacing

R‧‧‧ film roll

Fig. 1 is a cross-sectional view showing a schematic configuration of a liquid crystal display device according to an embodiment of the present invention.

Fig. 2 is an explanatory view schematically showing an example of a manufacturing apparatus for producing an optical film by a solvent flow plastic film forming method.

Fig. 3 is a horizontal sectional view showing a flow molding die of the above manufacturing apparatus.

Fig. 4 is an explanatory view showing an example of a configuration of a winding device included in the above-described manufacturing apparatus.

Fig. 5 is a perspective view showing the appearance of a film roll formed by winding of the above optical film according to the above winding device.

Figure 6 is a cross-sectional view along the width direction of the film roll.

Fig. 7 is an explanatory view schematically showing another configuration of the above winding device.

Fig. 8 is an explanatory view showing a state in which an optical film is wound and wound by the winding device of Fig. 7;

Fig. 9 is a cross-sectional view showing an example of a positional relationship of a layer which is adjacent to a layer above and below a stacking direction by a wrap-around winding.

Fig. 10 is a cross-sectional view showing another example of the positional relationship of the layers adjacent to the upper and lower layers in the stacking direction by the wrap-around winding.

Hereinafter, the embodiment of the present invention will be described below with reference to the drawings. In addition, in this specification, the numerical value range is shown in the case of A~B, and it is set as the value of the lower limit A and the upper limit B in the numerical value range. Further, the present invention is not limited to the following contents.

The inventors of the present invention have tried to solve the above problems and have reviewed the following methods for producing a film roll. In other words, the method for producing a film roll of the present embodiment is a method for producing a roll of a film roll by winding an optical film on a winding core, wherein the optical film is oscillated in a relative manner with respect to the winding core. Simultaneously in the width direction, the optical winding is wound around the winding core, and the optical film has a plurality of concavities and convexities on the surface in the width direction, and is convex in the width direction of the optical film. When the pitch is P (mm), it is 13 mm ≦ P ≦ 40 mm ‧ ‧ (1), and is adjacent to the same cross section in the width direction of each layer of the optical film laminated by winding. When the amount of shift in the width direction between the layers in the stacking direction by the swing is A (mm), in the swing winding project, the layers adjacent to the stacking direction satisfy A>P‧‧ (2) A method of manufacturing a film roll characterized by the fact that the optical film is relatively oscillated with respect to the winding core. This feature is common to the technical features of the invention relating to each of the applications described in the patent application.

As described above, the offset amount A (the amount of swing, the amount of vibration) in the width direction of each layer of the optical film is set in consideration of the pitch P of the convex portions in the width direction of the optical film. Further, when the offset amount A is set to be larger than the pitch P, and the optical film is wound by relatively rotating the optical core, it is possible to suppress the film roll of the film roll in a high-temperature and high-humidity environment. Attachment. The discovery mechanism and the action mechanism for such an effect are not clear, but are estimated as follows.

When the pitch P is within the range satisfying the conditional expression (1), the optical film or the core is swung (periodically vibrated) in the width direction while satisfying the conditional expression (2), and the optical film is wound around the core. When a roll-shaped optical film (film roll) is obtained, for example, a convex portion of an upper layer which is continuously laminated in a film roll and a convex portion of a layer different from a cross section (for example, a film thickness) of the convex portion The departments overlap.

Here, in the upper and lower layers, the amount of shift in the width direction of the convex portion having the same cross section (for example, the convex portion having the largest film thickness) is small, and the pressure generated by the winding is concentrated in the same range in the width direction. (There is a range of convex portions having the same cross section in the width direction), and agglomeration is likely to occur. However, when the swing of the conditional expression (2) is satisfied, the convex portion of the upper layer is superposed on the convex portion of the layer different from the cross section, and the convex portion having a different cross section can be laminated. Alternatively, when the above-described wobble is applied, the convex portion of the upper layer and the concave portion of the lower layer may be laminated. As a result, it is possible to suppress local pressure from being generated by the pressure generated by the winding, and it is possible to sufficiently exhibit the effect of preventing the attachment via the swing. Accordingly, even when the film roll that is oscillated and bundled is stored in a high-temperature and high-humidity environment, the optical film can be locally adhered.

In this way, it is possible to suppress the local adhesion of the optical film, and it is possible to suppress a phase difference that is fluctuating due to a phase difference (for example, a retardation Rth in the thickness direction) passing through the optical film. As a result, an optical film is fed from a film roll to produce a polarizing plate, even if it is to be When the polarizing plate to be produced is suitable for a display device (for example, a liquid crystal display device), it is also possible to suppress uneven display due to a change in phase difference of the optical film.

Hereinafter, prior to the description of the method for producing a film roll of the present embodiment, the liquid crystal display device to which the optical film is fed from the film roll to be produced and the configuration of the optical film will be described first.

[Vertical alignment type liquid crystal display device]

Fig. 1 is a cross-sectional view showing a schematic configuration of a vertical alignment type (VA type) liquid crystal display device 1 of the present embodiment. The liquid crystal display device 1 includes a liquid crystal display panel 2 and a back surface light source 3. The back light source 3 is a light source for illuminating the liquid crystal display panel 2.

In the liquid crystal display panel 2, the polarizing plate 5 is disposed on the side of the liquid crystal cell 4 driven by the VA method, and the polarizing plate 6 is disposed on the side of the back surface light source 3. The liquid crystal cell 4 is formed by sandwiching a liquid crystal layer with a pair of transparent substrates (not shown). A color filter can be used as the liquid crystal cell 4, and a transparent substrate disposed on the side of the back surface light source 3, that is, a substrate on the side of a TFT (Thin Film Transistor), a color filter array (COA) The liquid crystal cell of the structure, but may be a color filter, and the liquid crystal layer is disposed on the liquid crystal cell of the transparent substrate on the identification side.

The polarizing plate 5 includes a polarizer 11 and an optical film 12‧13. The polarizer 11 is transmitted through a specific linear polarization. Optical film 12 series A protective film disposed on the identification side of the polarizer 11 is disposed. The optical film 13 is a protective film and a retardation film which are disposed on the side of the back light source 3 (on the liquid crystal cell 4 side) of the polarizer 11. The polarizing plate 5 is attached to the identification side of the liquid crystal cell 4 by the adhesive layer 7. In other words, the polarizing plate 5 is positioned on the identification side of the liquid crystal cell 4, and the optical film 13 is attached to the liquid crystal cell 4 so as to be on the liquid crystal cell 4 side with respect to the polarizer 11.

The polarizing plate 6 is provided with a polarizer 14 and an optical film 15‧16. The polarizer 14 is transmitted through a specific linear polarization. The optical film 15 is disposed on the side of the identification side of the polarizer 14 and functions as a phase difference film. The optical film 16 is a protective film disposed on the side of the back light source 3 of the polarizer 14. The polarizing plate 6 is attached to the back light source 3 side of the liquid crystal cell 4 by the adhesive layer 8. However, the optical film 15 on the identification side is omitted, and the polarizer 14 may be directly in contact with the adhesive layer 8. The polarizer 11 and the polarizer 14 are arranged in a crossed state.

The optical film of the present embodiment is formed, for example, by a solvent flow plastic film forming method to be described later, and is applied to the optical film 13 of the polarizing plate 5 or the optical film 15 of the polarizing plate 6. Hereinafter, the details of the optical film of the present embodiment will be described.

[For optical film]

The optical film may be a film made of a thermoplastic resin, but it is desirable for use in optical applications. A film made of a resin having a transparent property in terms of wavelength is preferred. Examples of the resin constituting such a film include a polycarbonate resin, a polyether oxime resin, a polyethylene terephthalate resin, a polyamidene resin, and a polymethyl methacrylate resin. , polyfluorene-based resin, polyarylate resin, polystyrene resin, polyvinyl chloride resin, olefin polymer resin (alicyclic olefin polymer resin) having an alicyclic structure, cellulose ester resin Wait.

Among them, a polycarbonate resin, an alicyclic olefin polymer resin, or a cellulose ester resin is preferred from the viewpoints of transparency and mechanical strength. Among them, it is more preferable to adjust the cellulose ester-based resin in which the phase difference as the optical film is easy.

(cellulose ester resin)

Preferred examples of the cellulose ester-based resin include deuterated cellulose satisfying the following formulas (1) and (2).

Equation (1) 2.0≦Z1<3.0

Formula (2) 0≦X<3.0 (In formulas (1) and (2), Z1 represents the total thiol substitution degree of deuterated cellulose, the substitution ratio of thiol group of X-type deuterated cellulose and butyl sulfhydryl substitution The sum of degrees).

The cellulose which is a raw material of the cellulose ester may, for example, be cotton linter, wood pulp, kenaf or the like, but is not particularly limited thereto. Further, the cellulose ester obtained from the above may be mixed in an arbitrary ratio to the user.

The total thiol substitution degree of deuterated cellulose is in the range of 2.0 to 2.7. Internal cellulose, but from the viewpoint of improving water resistance, in addition, the flow plasticity and elongation at the time of film formation are improved, and the uniformity of film thickness is further improved, and the total thiol substitution degree of deuterated cellulose is 2.1~2.5 is better.

However, the degree of substitution of the thiol group or the substitution of other thiol groups may be in accordance with ASTM-D817-96, one of the specifications issued by ASTM (American Society for Testing and Materials). Measurer.

The deuterated cellulose system is particularly selected from the group consisting of cellulose acetate (diacetate cellulose, cellulose triacetate), cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate benzoate, cellulose propionate, butyric acid fiber. At least one of the compounds is preferred, but among them, cellulose acetate, cellulose acetate propionate, and cellulose acetate butyrate are more preferred.

The weight average molecular weight (Mw) of the cellulose ester-based resin is preferably 75,000 or more, more preferably in the range of 75,000 to 300,000, more preferably in the range of 100,000 to 240,000, and particularly preferably in the range of 10,000 to 20,000. When the weight average molecular weight (Mw) of the cellulose ester-based resin is 75,000 or more, it is preferable to exhibit the effect of improving the self-filming property or adhesion of the layer containing the cellulose ester-based resin.

The number average molecular weight (Mn) and the weight average molecular weight (Mw) of the cellulose ester-based resin can be measured by the following measurement conditions by gel permeation chromatography.

Solvent: dichloromethane

Columns: Shodex K806, K805, K803G (connected to three Japanese Showa Denko (shares) system)

Column temperature: 25 ° C

Sample concentration: 0.1% by mass

Detector: RI Model 504 (made by GL sciences)

Gang: L6000 (made by Hitachi, Ltd., Japan)

Flow rate: 1.0ml/min

Calibration curve: A calibration curve of 13 samples in the range of Mw = 500 to 2800000 using standard polystyrene STK standard polystyrene (manufactured by Tosoh Co., Ltd., Japan). 13 sampling systems are preferred for use at slightly equal intervals.

(delay riser)

The optical film of the present embodiment may be used as a retardation film, and may contain a retardation-increasing agent. The retardation-increasing agent is a compound having a function of increasing the retardation of the film at a measurement wavelength of 590 nm (particularly, the retardation Rth in the thickness direction) compared to the case where the retardation-increasing agent is not added.

When the retardation agent is included in the optical film, the retardation in the in-plane direction and the retardation in the thickness direction of the optical film can be 30 nm<Ro<70 nm and 100 nm<Rth< as each of Ro and Rth. 300nm optical film.

For example, the above-mentioned Ro and Rth can be used for three times at a measurement wavelength of 590 nm in an environment of a temperature of 23 ° C and a relative humidity of 55% RH using an automatic birefringence meter axoscan (Axo Scan Mueller Matrix Polarimeter: manufactured by AXOMETRICS, Japan). The refractive indices n _x , n _y , and n _z obtained by measuring the refractive index of the element are calculated according to the following formula.

Ro=(n _x -n _y )×d(nm)

Rth={(n _x +ny)/2-n _z }×d(nm) (wherein n _x shows the refractive index in the in-plane direction of the film, the refractive index becomes the largest direction x, and the n _y system shows direction, a direction orthogonal to the direction of the refractive index x y, n-z, _z-based display of the refractive index in the thickness direction of the film in the plane of the film, d the thickness of the film-based displays (nm))

In the present embodiment, a nitrogen-containing heterocyclic compound having a molecular weight of from 100 to 800 can be used as a retardation increasing agent (additive). As the above nitrogen-containing heterocyclic compound, for example, those described in paragraphs [0140] to [0214] of International Publication No. WO2014/109350A1 can be used.

(additive)

The optical film of the present embodiment may contain at least one selected from the group consisting of a sugar ester, a polycondensation ester, and a polyol ester as the organic ester.

Further, the optical film of the present embodiment may contain a phosphate ester. Examples of the phosphate ester include a triaryl phosphate, a diaryl phosphate, a monoaryl phosphate, an aryl phosphate compound, an arylphosphine oxide compound, a condensed aryl phosphate, a halogenated alkyl phosphate, and a halogen-containing compound. A condensed phosphate ester, a halogen-containing condensed phosphonate, a halogenated phosphite, and the like.

Specific examples of the phosphate ester include triphenyl phosphate, 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide, phenylphosphonic acid, and tris(β-chloroethanol)phosphine. An acid ester, a tris(chloropropyl)phosphonate, a tris(tribromoneopentyl)phosphonate or the like.

Further, as one of the polyol esters, an ester of glycolic acid (glycolate compound) can be used. The glycinate compound is not particularly limited, but an alkylphthalic acid alkyl glycolate can be preferably used.

Examples of the alkylphthalic acid alkyl glycolate include methyl phthalic acid methyl glycolate, ethyl phthalic acid ethyl glycolate, and C. Phthalic acid propyl glycolate, butyl phthalic acid butyl glycolate, octyl phthalic acid octyl glycolate, methyl phthalic acid ethyl Glycolate, ethylphthalic acid methyl glycolate, ethyl phthalic acid propyl glycolate, methyl phthalic acid butyl glycolate, ethyl ortho Benzoyl butyl glycolate, butyl phthalic acid methyl glycolate, butyl phthalic acid ethyl glycolate, propyl phthalic acid butyl glycol Acid salt, butyl phthalic acid propyl glycolate, methyl phthalic acid octyl glycolate, ethyl phthalic acid octyl glycolate, octyl phthalate Formamidine methyl glycolate, octyl phthalate ethyl glycolate, etc., and ideally ethylphthalic acid ethyl glycolate.

Further, the optical film of the present embodiment may further contain fine particles (flatting agent) as necessary in order to improve the slidability of the surface. The above fine particle system may also be inorganic fine particles or organic fine particles. For inorganic Examples of microparticles include cerium oxide (cerium oxide), titanium dioxide, aluminum oxide, zirconium oxide, calcium carbonate, calcium carbonate, talc, clay, calcined kaolin, calcined calcium citrate, calcium citrate hydrate, and citric acid. Aluminum, magnesium citrate and calcium phosphate. Among them, cerium oxide or zirconium oxide is preferred, and cerium oxide is more preferable in order to reduce the turbidity of the obtained film.

Examples of the fine particles of cerium oxide include Aerosil R972, R972V, R974, R812, 200, 200V, 300, R202, OX50, TT600, NAX50 (made by Japan Aerosil Co., Ltd.), SEAHOSTAR KE-P10, KE- P30, KE-P50, KE-P100 (above Japanese catalyst (share) system).

(Method of manufacturing optical film)

Next, a method of producing an optical film of the present embodiment (a method of producing a film roll) will be described. FIG. 2 is a schematic configuration view showing a manufacturing apparatus 20 used in the production of the optical film of the embodiment. The method for producing an optical film of the present embodiment is a method for forming an optical film by a solvent flow plastic film forming method. In the solvent flow plastic film forming method, a dopant containing a resin and a solvent is flow-molded from a flow molding die onto a running support, dried on a support, and a flow plastic film is peeled off from the support (web) After that, the web is stretched and dried to form a film. Hereinafter, the production of an optical film by a solvent flow plastic film forming method will be described in more detail.

(dopant modulation engineering)

Modulation of the flow molding on the support 22 by a modulation unit not shown Agent.

(flow molding, drying, stripping engineering)

Next, the dopant prepared by the modulation unit is flow molded from the flow molding die 21 onto the support 22. Further, the web 25 which is a fluidized film formed by being conveyed while being supported by the support 22 is peeled off from the support 22 . For more systems as below.

The dopant prepared by the modulation unit is transported to the flow molding die 21 via a conduit by a pressurizing type quantitative gear pump or the like, and the support 22 which is rotationally driven by the stainless steel circulating belt is transferred infinitely. At the upper flow molding position, the self-flow molding die 21 fluid-fills the dopant, thereby forming a web 25 as a flow-through film on the support 22.

The support 22 is held by a pair of columnar bodies 23‧23 and a plurality of rollers (not shown) positioned between them. A drive device (not shown) that applies tension to the support 22 is provided to one or both of the columnar bodies 23‧23, whereby the support 22 is used in a state of being expanded by tension.

The web 25 formed by molding the dopant on the support 22 is heated on the support 22, and the web 22 is peeled off from the support 22 until the web 25 is peeled off by the peeling roller 24. evaporation. The method of evaporating the solvent is a method of blowing air from the web side, or a method of transferring heat from the back surface of the support 22 via a liquid, a method of transferring heat from the surface by radiant heat, or the like, as appropriate, alone or in combination. Just use it. Until the support 22 has a film strength of the peelable web 25, After drying or solidifying or cooling and solidifying, the web 25 is self-supporting and peeled off via the peeling roller 24.

However, the amount of the residual solvent of the web 25 on the support 22 at the time of peeling is preferably the strength of the drying, the length of the support 22, and the like, and is preferably in the range of 50 to 120% by mass. When the amount of residual solvent is more than that, the web 25 is too soft and loses the flatness at the time of peeling, and is likely to have wrinkles or vertical stripes through the peeling tension, and is economical and quality. The amount of residual solvent at the time of peeling is determined by equalization. Further, the amount of residual solvent is defined by the following formula.

Residual solvent amount (% by mass) = (mass before heat treatment of the web - mass after heat treatment of the web) / (mass after heat treatment of the web) × 100

Here, the heat treatment in the case where the amount of the residual solvent is measured means that the heat treatment is performed at 115 ° C for 1 hour.

(extension project)

In this process, the web 25 peeled off from the support 22 is extended by the tenter 26. In this case, the direction of the film transport direction (MD direction) is perpendicular to the width direction (TD direction) of the transport direction in the film plane, and any of these two directions. In the case of a film for a film-forming liquid crystal display device, in a stretching process, a tenter pattern in which both side edges of the web 25 are fixed by a clip or the like is stretched, and it is ideal for improving the planarity or dimensional stability of the film. . However, in the tenter 26, added to It can also be dried by stretching.

(drying project)

The web 25 extended by the tenter 26 is dried by a drying device 27. In the drying device 27, the web 25 is meandered by a plurality of conveying rollers arranged in a staggered manner from the side, and the web 25 is dried therebetween. The drying method of the drying device 27 is not particularly limited, and the web 25 is generally dried by using hot air, infrared rays, heating rollers, microwaves or the like. From the point of simplicity, the method of drying the web 25 with hot air is preferred.

The web 25 is dried by the drying device 27, and then conveyed as an optical film F toward the winding device 40. Accordingly, at least one of the processes from the flow molding to the drying of the dopant described above is included in the film forming process for forming the optical film F via the solvent flow plastic film forming method.

(cutting, embossing processing)

The drying device 27 and the winding device 40 are arranged in the order of the cutting portion 28 and the embossed portion 29. In the cutting unit 28, the optical film F formed by the film is conveyed, and the cutting process at both end portions in the width direction is cut by the cutter. In the optical film F, the portion remaining after the cutting of both end portions constitutes a product portion which becomes a film product. On the other hand, the portion (trimmed portion) cut from the optical film F is recovered by the chute and used for film formation of the next film.

After the cutting process, the width direction of the optical film F Both ends are subjected to embossing (knurling) via the embossed portion 29. The embossing process is performed by pressing the heated embossing rolls against both end portions of the optical film F. Fine irregularities are formed on the surface of the embossing roller, and the embossing rollers are pressed against the both end portions of the optical film F, and irregularities are formed at the both end portions. By such embossing, it is possible to suppress the offset or agglomeration of the winding process (attachment of the films to each other) in the following winding work as much as possible.

(winding engineering)

Finally, the optical film F whose forming of the embossed portion is finished is wound by the winding device 40 to obtain a main roll (film roll) of the optical film F. That is, in the winding process, when the optical film F is simultaneously wound around the winding core, the film roll is produced. The winding method of the optical film F is a method of using a hoist generally used, and a method of controlling a torsion force method, a constant tension method, a push-pull tension method, and a program tension control method in which internal stress is constant, If you use this separately. It is preferable that the length of the optical film F is 1000 to 7200 m.

(for the details of the flow rate die)

Next, the details of the flow rate die 21 described above will be described. Figure 3 is a horizontal sectional view of the flow molding die 21. The flow velocity die 21 has a slit 31 which serves as an outlet of the dopant. The slit 31 is formed by a pair of ribs. One of the ribs has a low rigidity, and the deformable rib 32 is easily deformed, and the other rib is a fixed rib 33.

Further, the flow rate die 21 is provided with a plurality of thermal bolts 34 provided with slit gap adjusting members for adjusting the width of the slit 31 (the length of the dopant flow direction). The plurality of heat bolts 34 are arranged at a slightly constant interval and arranged in the width direction of the flow velocity die 21 (the longitudinal direction of the slit 31). However, the spacing of the plurality of thermal bolts 34 can also be set to any value.

The flow rate die 21 is provided with a member (not shown) in which an electric heater and a cooling medium passage are embedded, and is provided corresponding to each of the heat bolts 34, and each of the bolts 34 penetrates each member. At the same time, the above-mentioned components are often air-cooled, and the input of the electric heater is increased or decreased, and the temperature of the components is raised and lowered. When the heat bolts 34 are thermally expanded and contracted, the flexible ribs 32 can be displaced and the gap gap can be adjusted. Thereby, the thickness of the dopant which is flow-molded from the slit 31 to the support 22 is adjusted, and the thickness of the optical film can be adjusted. The thickness of the optical film is, for example, 15 to 60 μm , but is desirable at the point where the optical film of the film can be realized.

At this time, the heat bolts 34 are distributed in the width direction of the flow velocity die 21, and the amount of adjustment of the gap gap is uneven via the position of the slit 31 in the width direction (see FIG. 3). Therefore, the thickness unevenness of the dopant which is flow molded on the support 22 is generated in the width direction, and is caused by uneven thickness (surface unevenness) in the width direction of the optical film of the formed film. That is, the surface of the optical film of the film formed is arranged in the width direction to form a concave portion or a convex portion corresponding to the position of each of the heat bolts 34. However, the concave portion and the convex portion of the optical film are formed in an optical film and formed on a surface opposite to the support 22 at the time of fluid flow. Incidentally, in the optical film, the surface on the side of the support 22 at the time of flow molding is in contact with the support 22, and is flat. When the thickness of the convex portion of the optical film (corresponding to the difference in film thickness between the convex portion H2 and the concave portion L1 in Fig. 9) is 5 μm or less, it is desirable from the viewpoint of the effects of the present embodiment.

However, since the amount of adjustment of the gap gap between the respective heat bolts 34 is uneven, the thickness (height) of the convex portions of the optical film is not uniform in the width direction, and there are also a plurality of thicknesses in the convex portions. Evenly (see Figure 9).

(for the details of the winding device)

Next, the details of the winding device 40 used in the above winding process will be described. FIG. 4 is an explanatory view showing an example of the configuration of the winding device 40. The winding device 40 includes a winding core 41 that winds the optical film F, and a drive mechanism 42 that drives the winding core 41. The drive mechanism 42 includes a first drive mechanism 42a that rotates the winding core 41 in the circumferential direction, and a second drive mechanism 42b that swings the winding core 41 in the width direction of the optical film F (the direction of the rotation axis of the winding core). The first drive mechanism 42a and the second drive mechanism 42b are configured by a mechanical drive mechanism including a motor, a gear, a shaft, and a cam mechanism.

In addition, the transport roller 43 that transports the optical film F toward the winding core 41 is disposed on the upstream side of the winding direction of the winding core 41. The transport roller 43 may be configured as a single roller as shown in the figure, or may be constituted by a pair of rollers, and the optical chuck may be clamped. The film F is conveyed.

When the winding core 41 is rotated in the circumferential direction and the optical core F is relatively oscillated in the width direction by the winding mechanism 41, the optical film F is periodically changed in the winding position. At the same time in the width direction, the winding core 41 is wound into a roll, and becomes the film roll R shown in FIG. In the film roll R, as shown in Fig. 6, the optical films F of the respective layers are periodically shifted in the width direction while being laminated. However, the cross-sectional view of Fig. 6 corresponds to a cross-sectional view of the film roll R of Fig. 5 when the plane S including the width direction is cut. In addition, in FIG. 6, it is convenient to make the thickness of the optical film F of each layer into the width direction uniform, but it is actually the thickness unevenness in the width direction (refer FIG. 9).

FIG. 7 is an explanatory view schematically showing another configuration of the winding device 40. The winding device 40 is added to the configuration of FIG. 4, and may include a clamping roller 44 and a drive mechanism 45. The nip roller 44 is formed by a pair of rollers 44a and 44b, and is disposed between the winding core 41 and the conveying roller 43 at a position different from the conveying roller 43. The drive mechanism 45 includes a first drive mechanism 45a that rotates the respective rollers 44a and 44b of the clamp roller 44 in the circumferential direction, and swings the respective rollers 44a and 44b in the width direction of the optical film F (roller The second drive mechanism 45b in the direction of the rotation axis. The first drive mechanism 45a and the second drive mechanism 45b are configured by a mechanical drive mechanism including a motor, a gear, a shaft, and a cam mechanism. However, in FIG. 7, the drive mechanism 42 for driving the winding core 41 is configured only by rotating the winding core 41 in the circumferential direction of the first drive mechanism 42a. However, similarly to FIG. 4, the winding core 41 is provided to be oscillated. Yu Kuan The second drive mechanism 42b in the direction of the drive may drive one or both of the second drive mechanism 42b and the second drive mechanism 45b.

When the rollers 44a and 44b of the pinch roller 44 are rotated in the circumferential direction via the drive mechanism 45, and the respective rollers 44a and 44b are simultaneously swung in the width direction, as shown in FIG. 8, the optical film F is as shown in FIG. In the case of the winding core 41, the winding core 41 is wound in a roll shape in a roll shape in the width direction. As a result, a film roll R similar to that of Figs. 5 and 6 was obtained.

As described above, in the winding device 40, one of the optical film F and the core 41 is relatively oscillated in the width direction perpendicular to the conveyance direction of the optical film F, and the optical film F is wound. In the core 41. Hereinafter, the winding method of the optical film F is also referred to as a swing winding, and the process of winding the optical film F around the winding core 41 via the wobbling is called a swing winding project.

However, in the configuration of Fig. 7, the drive mechanism 45 does not swing the respective rollers 44a and 44b of the nip roller 44 in the width direction, but in the plane of the optical film F, periodically for the width direction. When the angle of each of the rollers 44a and 44b is changed, the optical film F may be relatively oscillated in the width direction with respect to the winding core 41.

(for the details of the swing bundle)

Next, the details of the swing bundle of the present embodiment will be described. Fig. 9 is a cross-sectional view showing an example of the positional relationship between the layers of the optical film F adjacent to the stacking direction by the swing wrapping of the embodiment. here, The optical film F which is a target of the swing bundle is configured to have a plurality of irregularities on the surface in the width direction. In Fig. 9, the convex portion of the optical film F is conveniently referred to as H1, H2, and ‧ ‧ from the side end side, and the concave portion of the surface is displayed as L1, L2, and ‧ ‧ from the side end side . In the case where irregularities are formed on the surface of the optical film F as described above, the optical film F is formed by a solvent flow plastic film forming method, and the respective thermal bolts 34 are arranged in the width direction of the flow molding die 21. The amount of adjustment of the gap gap is uneven, and the thickness of the dopant in the width direction is uneven, and the thickness of the optical film F in the width direction is uneven. Further, since the amount of adjustment of the gap gap between the respective heat bolts 34 is uneven, the film thickness of each convex portion of the optical film F is also uneven in the width direction. However, in FIG. 9, it is convenient to isolate the two optical films F which are laminated on the upper and lower sides by winding, but actually constitute a partial contact.

The distance between the convex portions in the width direction of the surface of the optical film F is taken as P (mm). For example, the distance between the convex portion H1 and the convex portion H2 in the width direction (the distance between the vertices), and the distance between the convex portion H2 and the convex portion H3 in the width direction (the distance between the vertices) are simultaneously P. Further, in the same cross section (the cross section when the plane S is cut in the plane S of FIG. 5) including the respective layers of the optical film F laminated by winding, the layers adjacent to each other in the stacking direction are passed through each other. The amount of shift (swing amount) in the width direction of the wobble is taken as A (mm). However, the vibration amplitude of the swing through the width direction is one-half of the above-described offset amount, that is, A/2.

The offset of the width direction of each layer of the optical film F is A In the cross section, for example, the convex portion H1 of the upper layer and the convex portion H1 of the lower layer are shifted by only A in the width direction, and the concave portion L1 of the upper layer and the concave portion L1 of the lower layer are shifted by only A in the width direction. However, by appropriately setting the period of the wobble and the rotation period of the winding core 41, it is possible to laminate the layers in the width direction and laminate them in the above-described cross section.

In the present embodiment, when the distance P is 13 mm ≦ P ≦ 40 mm ‧ ‧ (1), in the swing winding project, the layers adjacent to the stacking direction satisfy A>P‧ In the case of the optical film F, the optical film F is wound in a relative manner with respect to the winding core 41 (see FIG. 4 and the like).

When the pitch P is within the range of the conditional expression (1), the film roll R is obtained by swinging the optical film F or the core 41 in the width direction while satisfying the conditional expression (2), for example, in the underlayer film. The convex portion H2 having the largest thickness and the convex portion H2 having the largest thickness of the upper layer are largely displaced from the width direction, and the convex portion H2 of the lower layer is overlapped with the convex portion H1 of the upper layer having a smaller thickness.

Here, FIG. 10 shows another example of the positional relationship of each layer of the optical film F adjacent to the lamination direction, and shows the position of the layer which is upper and lower when the optical film F is swung and is wound as A<P. relationship. As shown in Fig. 10, when A < P, the amount of shift in the width direction of the convex portion H2 having the same cross section (e.g., film thickness) in the upper and lower layers is small. In this case, the pressure generated by the winding is concentrated in a slightly the same range in the width direction (in the above In the example, the range W) of the convex portion H2 is present, and as a result, agglomeration is likely to occur.

However, in the present embodiment, when the conditional expression (2) is satisfied, as shown in FIG. 9, the upper and lower layers have overlapping convex portions having different cross sections (for example, one portion of the upper convex portion H1 and the lower convex portion H2). Some of them overlap, and although not shown, the convex portion of the upper layer and the concave portion of the lower layer overlap in the stacking direction. As a result, the pressure generated by the winding is not locally concentrated as shown in FIG. 10, and agglomeration is less likely to occur. Accordingly, the effect of preventing the attachment by the swing can be sufficiently exhibited.

Therefore, even if the film roll R is stored in a high-temperature and high-humidity environment, it is possible to suppress the presence of a portion attached to the optical film F and the unattached portion, and a phase difference occurs therebetween (for example, The retardation of the thickness direction Rth) is different in the phase difference. As a result, the optical film F is sent out from the film roll R to form a polarizing plate, and even when the polarizing plate to be produced is applied to a liquid crystal display device, display unevenness due to variation in phase difference of the optical film F can be suppressed.

In addition, when the pitch P of the convex portions in the width direction satisfies the conditional expression (1), it is possible to surely improve the roll quality. In the case where P>40 mm is satisfied, when the conditional expression (2) is satisfied, the offset amount A becomes excessively large, and there is a possibility that the folding winding is caused during the conveyance of the film roll R. In addition, when the film roll R is attached to the feeding device at the time of production of the polarizing plate, the end portion of the film roll R is in contact with the device, and the productivity of the polarizing plate is lowered. On the other hand, when P<13mm, the convex part The interval in the width direction is narrowed, and the oscillating condition is satisfied by the conditional expression (2), and random attachment is caused, and it is known that the film roll R having a good roll quality cannot be stably produced.

When the distance P is 20 mm ≦P ≦ 30 mm ‧ ‧ (1a), in the oscillating winding project, between the layers adjacent to the stacking direction, the above A>P is satisfied, and the thickness is 25 mm. A ≦ 35 mm ‧ (3), it is preferable that the optical film F is relatively oscillated with respect to the winding core 41.

When the pitch P is within the range satisfying the conditional expression (1a), the range of the pitch P and the offset A is optimized by swinging when the conditional expressions (2) and (3) are satisfied. The effect of preventing the adhesion of the optical film F is obtained, and the unevenness of the phase difference of the optical film F can be surely suppressed. As a result, in the liquid crystal display device, it is possible to reliably suppress the display unevenness caused by the phase difference fluctuation of the optical film F. Further, in the case where the distance P between the conditional expressions (1a) is satisfied, the offset amount A is completed in a minimum amount necessary, and the mechanism for swinging without increasing the size (for example, the drive mechanism 42‧45), and The above effects can be obtained by complication.

However, as described above, in each layer of the optical film F, the thickness of each convex portion arranged in the width direction is not completely the same, and there is unevenness between the convex portions. When the thicknesses are not large between the convex portions arranged in the width direction (for example, the difference between the maximum value and the minimum value of the thickness of the convex portion is 0.1 μm or more), for example, when A>P, Even if A=nP (however, n is an integer of 2 or more), the convex portion of different cross-sections can be superimposed on the lamination direction between adjacent layers by the wobble, and the above-mentioned one can be obtained. The effect of the embodiment. However, in the case of A≠nP, the convex portions having the same cross-section are surely offset from each other in the width direction and laminated, and of course, the effects of the above-described embodiment can be obtained. On the other hand, the thickness is not small between the convex portions arranged in the width direction (for example, the difference between the maximum value and the minimum value of the thickness of the convex portion is larger than 0 μm , and less than 0.1 μ. In the case of m), it is also possible to carry out the swinging of A=nP in A>P, but in the case of A>P, and the swinging bundle which is A≠nP is placed between adjacent layers. The same convex portions are shifted from each other in the width direction, and it is desirable to obtain the effect of the embodiment in which the film is prevented from sticking.

In the method for producing the film roll R of the present embodiment, the film optical film F is formed by a solvent flow plastic film forming method, and the film forming process described above is included. Further, in the swing winding process, the optical film F formed by the film forming process is relatively oscillated and wound around the winding core 41. The optical film F is formed by a solvent flow plastic film forming method. As described above, it is easy to cause thickness unevenness in the width direction of the optical film F, and when it is appropriately oscillated, film attachment occurs. Therefore, the method of swinging the winding of the present embodiment in which the adhesion preventing effect of the film is sufficiently exhibited can be sufficiently effective.

[Examples]

Hereinafter, the embodiments of the present invention will be specifically described, but the present invention is not limited to the embodiments.

<Example 1> (dopant composition)

The material of the above dopant composition was placed in a sealed container, and the temperature was raised until the liquid temperature became 80 ° C, and then stirred for 3 hours. By doing so, a cellulose acetate propionate resin solution was obtained. Thereafter, the stirring was completed, and the liquid temperature was allowed to stand at 43 °C. Further, the obtained resin solution was filtered using a filter paper having a filtration accuracy of 0.005 mm, and the bubbles in the resin solution were defoamed by leaving the resin solution filtered overnight. The thus obtained resin solution was used as a dopant, and the stainless steel strip having a width of 2200 mm was uniformly molded by a self-flow molding die at a temperature of 35 ° C using a manufacturing apparatus shown in FIG. 2 . Support on the body. However, in the flow molding die, the interval of the heat bolt in the width direction is 12 mm.

Next, on the stainless steel belt support, the solvent was evaporated until the amount of the residual solvent became 100% by mass, and the web (film) was peeled off from the stainless steel belt support. Next, both end portions in the width direction of the web are held by the tenter in the width direction (TD direction). At this time, the stretching ratio is 16.25%. Thereafter, the roller transport drying device provided with the transport roller 500 is subjected to a drying process, and then the cut ends are used to remove both ends of the film by a cutter. Further, the embossing for winding was performed on the single side of the film from the film end portion in the range of 13 mm in width, and then the film was wound through a winding device to obtain a film having a length of 5,200 m and a film thickness of Film roll of a wound body of a 30 μm cellulose ester film.

In the above-described winding device, specifically, as follows, a film roll is wound into a roll to form a film roll. In other words, a film which is embossed at both ends in the width direction is applied to the winding core at a speed of 80 m/min, a winding initial tension of 140 N, a winding end tension of 90 N, and a contact roller holding force of 20 N. A film roll was produced by winding 5200 m. Further, when the film is wound around the winding core, the winding core is periodically vibrated in the width direction, and the winding is performed by the winding (winding and winding).

Here, the film thickness in the width direction of the film surface is measured using a film thickness measuring device (a total infrared ray thickness measuring machine manufactured by EGS), and the pitch P of the convex portions in the width direction is calculated. P = 13 mm, and is 0.1 μm when the difference between the maximum value and the minimum value of the thicknesses of the convex portions in the width direction is obtained. Further, in the winding device, the amount of the displacement A in the width direction in the same cross section including the width direction in the respective layers of the film which is laminated by the winding is 18 mm larger than the above P, and is controlled. Drive of the core (vibration in the width direction).

<Examples 2 to 7, Comparative Examples 1 to 3>

A film roll was produced in the same manner as in Example 1 except that the stretching ratio of the film and the amount of shift A in the width direction of each layer of the film laminated by winding were changed as shown in Table 1. However, in the examples 2 to 7, after the distance P between the convex portions in the width direction of the film to be formed, the offset amount A was set to be larger than the distance P, and the film was wound and wound to produce a film roll. Further, in Comparative Examples 1 to 3, the offset A was set to be smaller than the pitch P, and the winding was performed by swinging to form a film roll.

<Measurement of retardation value>

From each of the film rolls produced in Examples 1 to 7 and Comparative Examples 1 to 3, an optical film was dispensed, and a sample film of 10 points was arbitrarily cut out, and an automatic birefringence meter axoscan (Axo Scan Mueller Matrix Polarimeter: AXOMETRICS, Japan) was used. The measurement of the three-dimensional refractive index in a wavelength of 590 nm in an environment of 23 ° C and 55% RH (relative humidity), and substituting the obtained average refractive index nx, ny, and nz into the following formula (i) And (ii), the retardation Ro1 in the in-plane direction and the retardation Rth1 in the thickness direction are obtained.

Formula (i): Ro = (nx - ny) × d (nm)

Formula (ii): Rth={(nx+ny)/2-nz}×d(nm) (in the formulas (i) and (ii), nx is expressed in the plane of the film The refractive index becomes the refractive index of the largest direction x. The ny system indicates the refractive index in the direction y orthogonal to the above-described direction x in the in-plane direction of the film. The nz line indicates the refractive index in the thickness direction z of the film. d is the thickness (nm) of the film)

Next, each of the film rolls produced in Examples 1 to 7 and Comparative Examples 1 to 3 was allowed to stand in an environment of 40 ° C and 90% Rn for 120 hours, and then left in an environment of 23 ° C and 55% RH for 24 hours. Further, in the same manner as described above, an optical film was fed from each film roll, and a sample film of 10 points was arbitrarily cut out, and a three-dimensional refractive index measurement was performed at a wavelength of 590 nm using an automatic birefringence meter axoscan to obtain an in-plane direction. The delay of Ro2 and the retardation of the thickness direction Rth2.

Then, the phase difference variation amount ΔRth in the thickness direction is obtained by the following equation.

ΔRth=Rth1-Rth2

<Production of polarizing plate>

The polyvinyl alcohol film having a thickness of 120 μm was uniaxially stretched (temperature: 110 ° C, stretching ratio: 5 times). Then, this polyvinyl alcohol film was immersed in an aqueous solution of 0.075 g of iodine, 5 g of potassium iodide, and 100 g of water, and then immersed in an aqueous solution of 6 g of potassium iodide, 7.5 g of boric acid, and 100 g of water to make a solution at 68 °C. The polyvinyl alcohol film was washed with water to obtain a polarizer.

Next, the optical films (retardation film) obtained in Examples 1 to 7, Comparative Examples 1 to 3, and the polarizers produced in the above, and KONICA MINOLTA TAC KC4UY (KONICA MINOLTA) were used. In the cellulose ester film (manufactured by the method), the above-mentioned polarizing plate having each optical film was produced in accordance with the following items 1 to 5.

Procedure 1: The optical film was immersed in a 2 mol/L sodium hydroxide solution at 60 ° C for 90 seconds, followed by washing with water, drying, and alkalizing with the polarizer-bonding side. Similarly, KONICA MINOLTA TAC KC4UY was immersed in the above sodium hydroxide solution for 90 seconds, followed by washing with water, drying, and alkalizing with the polarizer-bonding side.

Engineering 2: The aforementioned polarizer was immersed in a polyvinyl alcohol adhesive tank having a solid content of 2% by mass for 1 to 2 seconds.

Engineering 3: Wipe off excess adhesive attached to the polarizer in Project 2, and then optical film and KONICA MINOLTA TAC KC4UY which were alkalized in Project 1 were placed on each side of the polarizer, and the optical film/polarized light was applied. A laminate of sub/KONICA MINOLTA TAC KC4UY was produced for each of the optical films of Examples 1 to 7 and Comparative Examples 1 to 3.

Item 4: The obtained laminate was bonded via a roller machine at a pressure of 20 to 30 N/cm ² and a conveying speed of 2 m/min. The bonded laminate was dried for 2 minutes to prepare a polarizing plate. Further, two polarizing plates (identification side, back light source side) were produced in the same manner as described above.

<Production of Liquid Crystal Display Device>

The polarizing plates on both sides of the SONY 40-type display KLV-40J3000 which were previously bonded were peeled off, and the polarizing plates produced above were bonded to both surfaces of the glass surface of the liquid crystal cell (identification side, back light source side). At this time, the optical film of the polarizing plate is on the side of the liquid crystal cell, and the absorption axis is Each of the polarizing plates was bonded to the liquid crystal cell in the same direction as the polarizing plate to be bonded in advance, and each of the liquid crystal display devices was produced.

<Evaluation of uneven display>

In the environment of 23 ° C and 55% RH, the backlight of each liquid crystal display device was lighted for one week, and then EZ-Contrast 160D manufactured by ELDIM Co., Ltd. was used for white display and black display on the liquid crystal display device, and the self-display screen was measured. The brightness in the normal direction is compared to the front. That is, the front contrast (%) = {(the brightness of the white display measured from the normal direction of the display device) / (the brightness of the black display measured from the normal direction of the display device)} × 100. Further, the front side contrast of any five points of the liquid crystal display device was measured, and the unevenness of the front side contrast was evaluated as unevenness in display according to the following criteria.

Evaluation Benchmark

○: The front contrast has 0% or more, less than 5% is uneven, the unevenness is small, and there is no practical problem.

△: There are more than 5% of the front contrast, less than 10% of the unevenness, a slight unevenness, and no practical problem.

×: There is more than 10% unevenness in frontal contrast, and the unevenness is large, and there is a practical problem.

Table 1 shows the results of the respective parameters and evaluations of the optical films of Examples 1 to 7 and Comparative Examples 1 to 3.

From Table 1, the optical films of Examples 1 to 7 showed no unevenness in display, and there was no practical problem. In the method for producing a film roll of Examples 1 to 7, it is considered that even when the film roll is placed in a high-temperature and high-humidity environment, the phase difference variation (Rth variation) is also compared with Comparative Examples 1 to 3. Very small. In addition, in the first to seventh embodiments, it is possible to reduce the variation in the phase difference, and it is considered that the distance between the width direction of the convex portion of the optical film is 13 mm ≦ P ≦ 40 mm. In the oscillating winding process, the optical film is wound in a direction that satisfies A>P between the layers adjacent to the lamination direction by the winding of the optical film, and the optical film is relatively oscillated and wound around the winding core to obtain a film. Volume. In other words, it is considered that the convex portions having the same cross-section are greatly shifted in the width direction between the layers adjacent to each other in the stacking direction by the above-described wobble winding, whereby the convex portions having different cross-sections overlap each other in the stacking direction. Alternatively, the convex portion and the concave portion are superposed on the lamination direction, and the pressure generated by the winding is not locally concentrated in the film surface, and the local agglomeration is less likely to occur.

Particularly in Examples 3 and 4, the best evaluation was obtained for the display unevenness. In the manufacturing methods of the third and fourth embodiments, the pitch P in the width direction of the convex portion is 20 mm ≦P ≦ 30 mm, and in the swing winding project, it is considered that A is satisfied between the layers adjacent to the stacking direction. >P, at the same time, the optical film is wound 25 mm ≦A ≦ 35 mm, and the optical film is relatively oscillated and wound for the winding core, and the range of the pitch P and the offset amount A via the oscillating is optimized. The roll quality of the film roll can be favorably maintained, whereby the locality via the optical film can be reliably suppressed The attached phase difference is changed.

Further, in the first to seventh embodiments, the difference between the maximum value and the minimum value of the thicknesses of the convex portions arranged in the width direction of the optical film is 0.1 μm , and the thickness of each convex portion is not large. When the vibration is performed in the direction of A>P, the convex portions having different cross sections or the convex portions and the concave portions overlap each other in the stacking direction between the layers adjacent to the stacking direction. Therefore, it is considered that it is difficult to produce localized agglomerates and the above-described effects are surely obtained.

However, in the above, an example in which an optical film is formed using a cellulose ester-based resin has been described, but it has been known that other resins (for example, a cycloolefin polymer resin, a polycarbonate resin, or an acrylic resin) are used. In the film optical film, when the film roll was produced, the same effects as those of the first to seventh embodiments were obtained by performing the same wobble winding as in the first to seventh embodiments. That is, it is understood that the above-described effects of the wrap-around windings shown in the first to seventh embodiments are not related to the material of the film.

The method for producing a film roll of the present embodiment described above can be expressed as follows.

A method for producing a film roll, which is a method for producing a roll of a film roll by winding an optical film on a winding core, characterized in that the optical film is relatively oscillated with respect to the winding core At the same time as the width direction, the optical winding film is wound around the winding core; the optical film has a plurality of irregularities on the surface in the width direction. When the distance between the convex portions in the width direction of the optical film is P (mm), it is 13 mm ≦ P ≦ 40 mm, and the width direction of each layer of the optical film laminated by winding is included. In the same cross section, when the amount of shift between the layers adjacent to the stacking direction in the width direction by the wobble is A (mm), in the wobble winding project, between the layers adjacent to the stacking direction, When the A>P is satisfied, the optical film is wound and relatively rotated with respect to the winding core.

2. The method for producing a film roll according to the above aspect, wherein the pitch P is 20 mm ≦P ≦ 30 mm, and in the oscillating winding process, the layer A is satisfied between the layers adjacent to the stacking direction. At the same time, at the same time, the optical film satisfies 25 mm ≦ A ≦ 35 mm, and the optical film is relatively oscillated for the winding core to be wound.

The method for producing a film roll according to the above aspect, wherein the difference between the maximum value and the minimum value of the thicknesses of the convex portions arranged in the width direction of the optical film is 0.1 μm. The above.

4. The method for producing a film roll according to any one of the items 1 to 3, further comprising a film forming process for forming the optical film by a solvent flow plastic film forming method; In the optical film formed by the film forming process, the optical film is relatively oscillated and wound around the winding core.

[Industry use possibility]

The present invention can be utilized in the case where a film roll is produced by winding an optical film on a winding core.

20‧‧‧Manufacturing device for the manufacture of optical films

21‧‧‧ Flow molding die

22‧‧‧Support

23‧‧‧ columnar body

24‧‧‧ peeling roller

25‧‧‧ peelable web

26‧‧‧ tenter

27‧‧‧Drying device

28‧‧‧cutting department

29‧‧‧ Embossing Processing Department

40‧‧‧Winding device

F‧‧‧Optical film

Claims (4)

A method for producing a film roll, which is a method for producing a roll of a film roll by winding an optical film on a winding core, characterized in that the optical film is relatively oscillated in the width direction with respect to the winding core At the same time, the optical film is wound around the winding core, and the optical film has a plurality of concavities and convexities on the surface in the width direction, and the distance between the convex portions in the width direction of the optical film is made P ( In the case of mm), it is 13 mm ≦P ≦ 40 mm, and in the same cross section including the width direction of each layer of the optical film laminated by winding, the oscillating layer is adjacent between the layers adjacent to the lamination direction. When the amount of shift in the width direction is A (mm), in the above-described swing winding process, the optical film satisfying A>P is provided between the layers adjacent to the stacking direction, and the optical film is used for the winding core. Rotate relatively and wind up. The method for producing a film roll according to the first aspect of the invention, wherein the pitch P is 20 mm ≦P ≦ 30 mm, and in the swing winding project, the layer A is satisfied between the layers adjacent to the stacking direction. At the same time, at the same time, the optical film satisfies 25 mm ≦ A ≦ 35 mm, and the optical film is relatively oscillated for the winding core to be wound. The method for producing a film roll according to the first or second aspect of the invention, wherein the difference between the maximum value and the minimum value of the thicknesses of the convex portions arranged in the width direction of the optical film is 0.1 μm. The above. The film according to any one of claims 1 to 3 The method for producing a roll, further comprising a film forming process for forming the optical film by a solvent flow plastic film forming method; and in the swing winding process, the optical film formed by the film forming process is The aforementioned core is relatively oscillated to wind up.