JP2010126326A - Film roll and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a film roll suppressing generation of winding deviation and black band, and a method for manufacturing the same. <P>SOLUTION: In the film roll, a polymer film 1 having a knurling part on both ends in a width direction is wound on the periphery of a winding core 5 in a multi-layer form. In a cross section for vertically dividing the film roll into two equal parts relative to a width direction (TD), the film roll has a layer 4 of an inert gas between the polymer films, and a thickness d of the inert gas layer is 3.0-5.0 μm on average. In the method for manufacturing the film roll, in a step for rolling-up the polymer film having the knurling parts on both ends in the width direction on the periphery of the winding core in the multi-layer form, the inert gas is fed to a space between the polymer film just before rolled-up and the outermost polymer film already rolled-up on the periphery of the winding core and the inert gas is fed to the space between the polymer films. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a film roll in which a polymer film is wound in a multilayer shape around a core and a method for producing the film roll.

  After the continuous production of the polymer film, it is common to produce the film roll by winding the produced polymer film in a multilayered form around the core, and store and store the film roll. In such a film roll, it is known that a knurling part is formed at at least one end in the width direction of the polymer film for the purpose of preventing winding misalignment or the like (Patent Document 1).

However, after storing such a film roll and unwinding and using a polymer film, the pressure due to the winding was relatively high at a location relatively close to the core, so the films adhered to each other to form a black band There was a problem of being. A black band is a phenomenon in which the adhesion part between films looks black in a strip shape on the appearance. When the polymer film is used in an application with high required performance such as an optical film, the portion where the black band was formed did not satisfy the required performance. In particular, when the polymer film is provided with a coat layer such as a back coat layer, a hard coat layer, a low refractive index layer, or a high refractive index layer, the occurrence of the black band is remarkable.
JP 2005-219272 A

  An object of this invention is to provide the film roll in which generation | occurrence | production of winding shift | offset | difference and a black band were suppressed, and its manufacturing method.

  The present invention is a film roll in which a polymer film having a knurling portion at both ends in the width direction is wound around in a multilayered manner around a core, and the film roll is secondarily perpendicular to the width direction. In the section to divide, it has a layer of an inert gas between polymer films, and the thickness d of this inert gas layer is 3.0-5.0 micrometers on the average.

  The present invention also provides a method in which a polymer film having a knurling portion at both ends in the width direction is wound around the core in a multilayer shape, and the most recently wound around the periphery of the polymer film and the core just before being wound. The present invention relates to a method for producing a film roll, wherein an inert gas is supplied between an outer polymer film and an inert gas is fed between the polymer films.

According to the present invention, the inert gas fed in the step of winding the polymer film around the winding core in a multilayered form is effectively held between the films of the film roll over time. Therefore, the generation of black bands can be effectively suppressed. Such an effect of the present invention can be effectively exhibited even when the polymer film is an optical film and / or when the polymer film has a coating layer.
According to the present invention, winding deviation in a film roll can be effectively suppressed.

(Film roll)
In the film roll according to the present invention, a polymer film is wound in a multilayer shape around a core, and has an inert gas layer between the polymer films.

  Specifically, the film roll of the present invention is a film roll 10 in which a polymer film 1 is wound in a multilayered manner around a core 5 as shown in FIG. 1 (A), as shown in FIG. 1 (B). In addition, an inert gas layer 4 is provided between the polymer films 1. FIG. 1A is a schematic sketch of an example of the film roll of the present invention. FIG. 1B shows a schematic diagram showing a cross section 50 that bisects the film roll 10 in FIG. 1A perpendicularly to the width direction TD, and an enlarged view of a main part thereof.

  In the present invention, the thickness d of the inert gas layer 4 is 3.0 to 3.0 on average in a cross section 50 (hereinafter simply referred to as a vertical bisected cross section) that bisects the film roll 10 perpendicular to the width direction. The thickness is 5.0 μm, and preferably 3.1 to 4.8 μm, more preferably 3.2 to 4.0 μm from the viewpoint of more effectively suppressing the occurrence of winding deviation and black band. If the thickness d is too small, the generation of black bands cannot be effectively suppressed. If the thickness d is too large, winding deviation occurs. The vertical bisected section of the film roll in which the thickness d of the inert gas layer 4 is determined is such that when the film roll is misaligned, the innermost polymer film layer in the film roll is in the width direction. Any cross section may be used as long as it bisects vertically.

  The inert gas layer 4 is a layer formed by holding an inert gas entrained during film roll production between the films.

The thickness d of the inert gas layer 4 is the thickness of the inert gas layer after the acceleration test, and a value measured by the following method is used.
First, after performing the acceleration test of a film roll, the said film roll is analyzed about a dimension three-dimensionally, and the image of the perpendicular | vertical bisection section 50 of a film roll is obtained with a digital camera (made by SONY). In the accelerated test, the film roll was heated from room temperature (23 ° C.) to 65 ° C. at a temperature rising rate of 21 ° C./day for 2 days, then kept at 65 ° C. and allowed to stand for 7 days. The temperature is returned to room temperature over 2 days at a temperature lowering rate per day.

Next, in the vertical cross-sectional image, the thickness of the inert gas layer 4 is calculated. Specifically, as shown in FIG. 2, the total cross-sectional area S _A (sum of the hatched area and the lattice area) of the film roll 10 including the core 5 and the cross-sectional area S _B (lattice area) of the core 5 are measured. and, by calculating the "S _a -S _B", to obtain a sum S _C of the cross-sectional area of the cross-sectional area and an inert gas layer of the film. The resulting S _C, by dividing the take-up length L _F of the film constituting the film roll 10 to obtain the sum d _S of the thicknesses of the inert gas layer of the film. The thickness d (d _G ) of the inert gas layer is obtained by subtracting the film thickness d _F from d _S. The film thickness d _F is an average value of actually measured values at arbitrary 10 points on the image of the perpendicular bisector of the film roll.

  Since the thickness of the inert gas layer 4 is the thickness in the vertical bisected section 50 of the film roll as described above, it is not affected by the height of the knurling portions that the polymer film 1 described later has at both ends in the width direction.

  The inert gas which forms the inert gas layer 4 will not be restrict | limited especially if the sticking between films can be prevented in a film roll, For example, air, nitrogen, helium, or those mixed gas is mentioned. Air is preferable from the viewpoint of reducing manufacturing costs.

  The winding length of the polymer film 1 constituting the film roll 10 is not particularly limited, and is preferably 1900 to 5200 m, particularly 1900 to 3900 m. The longer the winding length is, the more easily a black band is generated. However, in the present invention, even if a film roll is produced with such a relatively long winding length, the black band is effectively suppressed.

  The width of the polymer film 1 in the width direction is usually 1330 to 1960 mm, and particularly preferably 1330 to 1490 mm. The longer the width in the width direction, the more easily a black band is generated. However, in the present invention, even if such a relatively wide film roll is manufactured, the black band is effectively suppressed.

The thickness of the polymer film 1 is not particularly limited, and is usually 30 to 100 μm, particularly 30 to 80 μm, and preferably 40 to 80 μm. The thickness is the thickness in the region between the knurling portion in the width direction at both ends, in this specification, using the thickness d _F.

  The polymer film 1 has knurling portions at both ends in the width direction, and the knurling portions are formed with convex portions continuously in the moving direction of the polymer film. The vertical cross-sectional shape of the convex portion in the knurling portion with respect to the film moving direction is not particularly limited as long as the convex portion is continuously formed in the film moving direction. For example, the knurling portion 6 may be formed by continuously forming convex portions that are chevron-shaped in the moving direction as shown in FIG. 3 (A), as shown in FIG. 3 (B). As shown, the quadrangular convex portions may be formed continuously in the moving direction. 3 (A) to 3 (B) are enlarged cross-sectional views of one end in the width direction of the film in one embodiment of the present invention, showing a cross section perpendicular to the moving direction.

  When the polymer film does not have a knurling part or has a knurling part only at one end, and when the convex part of the knurling part is intermittently formed in the film moving direction, the inert gas between the films in the film roll Is difficult to maintain. Therefore, an inert gas layer cannot be formed effectively with a film roll, and the thickness d of the inert gas layer cannot be ensured.

The height h of the knurling part (convex part) is not particularly limited as long as it is larger than the thickness d of the inert gas layer, and is usually 25 to 35 μm, preferably 27 to 32 μm.
The width w of the knurling part is not particularly limited as long as winding deviation can be suppressed, and is usually 5 to 20 mm, preferably 8 to 15 mm.

  3 (A) and 3 (B), the knurling portion 6 is formed only on the upper surface of the film, but may be formed only on the lower surface, or formed on both surfaces. May be.

  The method for forming the knurling part is not particularly limited. For example, the heated embossing roll is pressed against at least both ends of the film to impart the shape of the surface of the embossing roll to the both ends, and is applied to both ends by laser irradiation. Methods and the like.

  As the polymer film in which the knurling portion is formed, a film made of a known polymer can be used. In particular, when a film unrolled from a film roll is used as an optical film, examples of the polymer constituting the polymer film include cellulose resin, polyester resin, acrylic resin, polyvinyl chloride resin, polyimide resin, norbornene. Examples thereof include resins and polyolefin resins. A preferred polymer film is a film made of a cellulose resin.

  The cellulose resin has a cellulose ester structure, and specific examples thereof include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, cellulose acetate butyrate, cellulose acetate phthalate, and cellulose phthalate. Etc. Among these, particularly preferable cellulose resins include cellulose acetate, cellulose propionate, cellulose butyrate, cellulose acetate propionate, and cellulose acetate butyrate. A cellulose resin may be used individually by 1 type, or may be used in combination of 2 or more type.

  The polymer film may contain additives such as an ultraviolet absorber, a plasticizer, and an inorganic metal oxide.

The glass transition temperature (hereinafter referred to as “Tg”) of the polymer film is usually 150 to 180 ° C., preferably 155 to 165 ° C.
The Tg of the polymer film is a value measured by applying DSC8230 (manufactured by Rigaku) to the polymer film.

  The polymer film may be produced by any known method, and can be produced, for example, by a so-called solution casting method or melt casting method.

  The polymer film may be stretched, and for example, a film stretched 1.05 to 1.5 times in each of the transport direction and the width direction may be used.

  The polymer film may have a coat layer. This is because the black band is easily generated when the coating layer is provided, but the black band is effectively suppressed even if the coating layer is provided in the present invention.

  In particular, when a polymer film is used as an optical film, examples of the coat layer that can be formed on the polymer film include a so-called back coat layer, hard coat layer, antireflection layer, and liquid crystal layer. The coat layer may be formed on one side or both sides of the polymer film.

  As shown in FIG. 1B, the winding core 5 may have a cylindrical shape or a columnar shape. The outer diameter of the core is not particularly limited, and is usually 70 to 310 mm, preferably 160 to 260 mm. As the material constituting the core 5, materials known in the field of film rolls can be used, and examples thereof include paper, FRP, and rubber.

(Film roll manufacturing method)
The above-described film roll of the present invention can be produced by the following method. That is, in the step of winding the polymer film having the knurling portions at both ends in the width direction around the winding core in a multilayer shape, the outermost film already wound around the winding core and the polymer film just before winding. An inert gas is supplied between the polymer film.

  Specifically, as shown in FIG. 4, in the step of winding the polymer film 1 having knurling portions at both ends in the width direction around the core 5 in a multilayer shape, the polymer film 1 a and the core just before being wound An inert gas 12 is supplied between the outermost polymer film 1b already wound around the substrate and the inert gas 12 is fed between the polymer films. When the polymer film 1 has a knurling portion on one surface, the polymer film 1 may be wound up so that the knurling portion forming surface faces the core 5 in the film roll 10 or facing the outside. It may be wound up.

  The inert gas 12 is preferably supplied toward the winding start point 13 of the polymer film, and the angle θ formed by the supply direction of the inert gas 12 and the film 1a immediately before winding is 0 to 0. 45 °, particularly 0 to 30 ° is preferred.

  The inert gas 12 is supplied by an inert gas supply means 20. The inert gas supply means 20 is not particularly limited as long as it can supply an inert gas. For example, an inert gas supply pipe having a plurality of supply ports can be used.

  An example of the inert gas supply pipe is shown in FIG. In FIG. 5, the inert gas supply pipe supplies the inert gas introduced into the pipe from one end or both ends to the outside of the pipe through a plurality of supply ports 21 provided in parallel in the axial direction K. Thus, supply in the axial direction K at a uniform wind speed is possible. The inert gas supply pipe is arranged so that the axial direction K is parallel to the width direction of the film 1.

  The inert gas supply means 20 passes the inert gas 12 in the width direction of the film between the polymer film 1a just before being wound and the outermost polymer film 1b already wound around the core 5. A plurality of supply nozzles composed of one supply port may be arranged in the width direction of the film as long as it can be supplied substantially uniformly.

  The thickness d of the inert gas layer in the film roll 10 is the wind velocity V of the inert gas 12 during the production of the film roll, the distance L from the gas supply pipe 20 to the winding start point 13, and the film 1 wound around the winding core 5. It can be controlled by adjusting the tension F until the film is taken and the winding speed of the film 1.

  For example, when the wind speed V is increased, the distance L is decreased, or the tension F is decreased, the thickness d of the inert gas layer is increased. For example, when the wind speed V is decreased, the distance L is increased, or the tension F is increased, the thickness d of the inert gas layer is decreased.

The wind velocity V of the inert gas 12 is usually 0.8 to 5.5 m / sec, preferably 1.5 to 5.0 m / sec.
The wind speed V is an initial wind speed of the inert gas immediately after being ejected from the inert gas supply means 20, and can be measured by measuring the inert gas immediately after the ejection with an anemometer.

  The distance L from the inert gas supply means 20 to the winding start point 13 is usually 10 to 340 mm, preferably 25 to 300 mm.

  The tension F until the film 1 is wound around the core 5 is usually 130 to 450 N / m, preferably 190 to 400 N / m.

  The inert gas 12 supplied by the inert gas supply means 20 is preferably subjected to ion generation treatment. By supplying the inert gas that has been subjected to the ion generation treatment, the static electricity on the film can be removed and the amount of charge can be reduced. As a result, it is possible to prevent the occurrence of foreign matter failure due to static electricity.

  The ion generation process is a process for generating ions in an inert gas. The method of ion generation treatment is not particularly limited as long as it can generate ions in an inert gas and ionize the inert gas. For example, by applying a high voltage to a plurality of needle electrodes, the inert gas around the electrodes The method of ionizing gas (especially air) is mentioned.

  The winding speed of the polymer film 1 is not particularly limited as long as the object of the present invention is achieved, and is usually 5 to 50 m / min, preferably 10 to 30 m / min.

(Use)
The polymer film unwound from the film roll of the present invention is suitable for use as an optical film because the generation of black bands is sufficiently suppressed. As an optical film, a viewing angle expansion film, a polarizing plate protective film, etc. are mentioned, for example.

[Example 1]
A cellulose ester film having a length of 2600 m, a width of 1.4 m, and a film thickness of 80 μm was produced by the method shown below. Subsequently, the knurling part was provided in the width direction both ends in one side of a transparent long base film by the method shown below. Next, a back coat layer was provided on the other surface of the base film by the method described below. Furthermore, after providing the hard-coat layer with the method shown below with respect to the knurling part formation surface of a base film, the antireflection layer was provided. The process so far was carried out continuously without winding up the film. Finally, the winding process was continuously performed by the method shown below.

<Production of cellulose ester film>
Cellulose triacetate (acetyl group substitution degree 2.9) 100 parts by weight Triphenyl phosphate 10 parts by weight Biphenyl diphenyl phosphate 2 parts by weight Tinuvin 326 (manufactured by Ciba Specialty Chemicals) 0.5 part by weight Aerosil R972V (Nippon Aerosil ( 0.2 parts by mass Methylene chloride 405 parts by mass Ethanol 45 parts by mass The above materials are put into a closed dissolution kettle and completely dissolved at 70 ° C. with stirring. After cooling, Azumi Filter Paper Co., Ltd. Azumi filter paper No. The dope was obtained by filtration using 244. The prepared dope was cast on a stainless steel belt. The solvent was evaporated on the stainless steel belt, and the web was peeled off from the stainless steel belt. The peeled web was introduced into a tenter dryer, and both ends were gripped with clips and dried at 80 ° C. while being stretched 1.1 times in the width direction. Inside a roll dryer having respective drying zones of 110 ° C. and then 125 ° C. The cellulose ester film was produced by carrying out drying while being conveyed through a large number of rolls arranged in the film.

<Formation of knurling part>
A heated predetermined embossing roll was pressed against both end portions on one surface of a cellulose ester film having a width of 1.4 m to provide a knurling portion. The knurling part has a mountain-shaped cross section as shown in FIG. 3A with respect to the moving direction, has a height h of 30.2 μm and a width w of 10 mm, and is continuously formed in the moving direction of the polymer film. It had been.

<Formation of back coat layer>
The following backcoat layer coating composition was die-coated on the other surface of the film to a wet film thickness of 13 μm, dried at a drying temperature of 90 ° C., and a backcoat layer was applied.
(Backcoat layer coating composition)
Acetone 30 parts by weight Ethyl acetate 45 parts by weight Isopropyl alcohol 10 parts by weight Diacetyl cellulose 0.5 parts by weight Ultrafine silica 2% acetone dispersion (Aerosil 200V) 0.2 parts by weight (manufactured by Nippon Aerosil Co., Ltd.)

<Formation of hard coat layer>
The following hard coat layer coating composition is die-coated in the region between the knurling portions at both ends of the knurling portion forming surface of the film, dried at 80 ° C. for 5 minutes, and then irradiated with 160 mJ / cm ² of ultraviolet rays, The hard coat layer was provided so that the total dry film thickness was 5 μm.
(Hardcoat layer coating composition)
Dipentaerythritol hexaacrylate 70 parts by weight Trimethylolpropane triacrylate 30 parts by weight Photoinitiator 4 parts by weight (Irgacure 184 (manufactured by Ciba Specialty Chemicals))
Ethyl acetate 150 parts by mass Propylene glycol monomethyl ether 150 parts by mass Silicon compound 0.4 parts by mass (BYK-307 (by Big Chemie Japan))
When the pencil hardness of the hard coat layer was measured, it showed a hardness of 3H and an abrasion resistance effect.

<Formation of antireflection layer>
An antireflection layer was formed on the hard coat layer. Specifically, the following coating solution for the medium refractive index layer is applied onto the hard coat layer using a bar coater, dried at 60 ° C., and then irradiated with ultraviolet rays to cure the coating layer. Rate 1.72) was formed. On top of that, the following coating solution for a high refractive index layer was applied using a bar coater, dried at 60 ° C., and then irradiated with ultraviolet rays to cure the coating layer, and a high refractive index layer (refractive index 1.9). Formed. Furthermore, the following coating solution for a low refractive index layer was applied using a bar coater, dried at 60 ° C., then irradiated with ultraviolet rays to cure the coating layer, and the low refractive index layer (refractive index 1.45). ) Was formed. As a result, an antireflection layer composed of the three layers was formed.

(Formation of medium refractive index layer / high refractive index layer / low refractive index layer)
(Preparation of titanium dioxide dispersion)
Titanium dioxide (primary particle mass average particle diameter: 50 nm, refractive index: 2.70) 30 parts by mass, anionic diacrylate monomer (PM21, Nippon Kayaku Co., Ltd.) 4.5 parts by mass, cationic methacrylate monomer (DMAEA, manufactured by Kojin Co., Ltd.) 0.3 parts by mass and 65.2 parts by mass of methyl ethyl ketone were dispersed by a sand grinder to prepare a titanium dioxide dispersion.

(Preparation of coating solution for medium refractive index layer)
In 151.9 g of cyclohexanone and 37.0 g of methyl ethyl ketone, 0.14 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and 0.04 g of a photosensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) were dissolved. Furthermore, after adding 6.1 g of the above titanium dioxide dispersion and 2.4 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, Nippon Kayaku Co., Ltd.) and stirring at room temperature for 30 minutes, The solution was filtered through a polypropylene filter having a pore diameter of 0.4 μm to prepare a coating solution for a medium refractive index layer. When this coating solution was applied to a cellulose ester film and dried and the refractive index after UV curing was measured, a medium refractive index layer having a refractive index of 1.72 and a dry film thickness of 85 nm was obtained.

(Preparation of coating solution for high refractive index layer)
In 1152.8 g of cyclohexanone and 37.2 g of methyl ethyl ketone, 0.06 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and 0.02 g of a photosensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) were dissolved. Furthermore, the ratio of the above titanium dioxide dispersion and the titanium dioxide dispersion of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, Nippon Kayaku Co., Ltd.) is increased, and the refractive index of the high refractive index layer is increased. The amount was adjusted so as to be a ratio, and the mixture was stirred at room temperature for 30 minutes, and then filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution for a high refractive index layer. When this coating liquid was applied to a cellulose ester film and dried, and the refractive index after UV curing was measured, a high refractive index layer having a refractive index of 1.9 and a dry film thickness of 68 nm was obtained.

(Preparation of coating solution for low refractive index layer)
Silane coupling agent (KBM-503, Shin-Etsu Silicone Co., Ltd.) 3 g and 0.1 mol / L hydrochloric acid 2 g are added to 200 g of methanol dispersion of silica fine particles having an average particle size of 15 nm (methanol silica sol, manufactured by Nissan Chemical Co., Ltd.). In addition, the mixture was stirred at room temperature for 5 hours and then allowed to stand at room temperature for 3 days to prepare a dispersion of silica fine particles treated with silane coupling. To 35.04 g of the dispersion, 58.35 g of isopropyl alcohol and 39.34 g of diacetone alcohol were added. Further, 1.02 g of a photopolymerization initiator (Irgacure 907, manufactured by Ciba Geigy) and a solution obtained by dissolving 0.51 g of a photosensitizer (Kayacure DETX, manufactured by Nippon Kayaku Co., Ltd.) in 772.85 g of isopropyl alcohol were added. Furthermore, 25.6 g of a mixture of dipentaerythritol pentaacrylate and dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku Co., Ltd.) was added and dissolved. 67.23 g of the resulting solution was added to the above dispersion, a mixture of isopropyl alcohol and diacetone alcohol. The mixture was stirred for 20 minutes at room temperature and filtered through a polypropylene filter having a pore size of 0.4 μm to prepare a coating solution for a low refractive index layer. When this coating liquid was applied to a cellulose ester film and dried, and the refractive index after UV curing was measured, the refractive index was 1.45 and the dry film thickness was 100 nm.

<Winding process>
The film 1 in which the formation of the knurling portion and each layer was completed was wound up in a multilayered manner around the core 5 as shown in FIG. At this time, between the film 1a immediately before being wound and the outermost film 1b that has already been wound around the core 5, the compressed gas 12 is wound around the film 1 by the inert gas supply pipe 20. 3 was supplied, and air was sent between the films. The wind speed V of the compressed air 12 is 0.8 m / sec, the angle θ formed by the supply direction of the compressed air 12 and the film 1 immediately before being wound is 15 °, and the wind is taken up from the inert gas supply pipe 20. The distance L to the starting point 13 was 200 mm. The tension F until the film 1 was wound around the core 5 was 400 N / m. The film 1 was wound up so that the knurling portion forming surface faced the outside of the roll. The core 5 had an outer diameter of 167 mm and a cylindrical shape made of FRP.

A schematic sketch of the inert gas supply pipe 20 is shown in FIG. The inert gas supply pipe 20 supplies compressed air introduced into the pipe from one end to the outside of the pipe through a plurality of supply ports 21 provided in a row in parallel with the axial direction K. Can be supplied at a uniform wind speed. The inert gas supply pipe 20 has 250 circular supply ports 2 having an opening diameter of 1.0 mm, an opening area s per supply port of 0.79 mm ² , a pitch p of 7.0 mm, and an axial length. Was 1750 mm, and the inner diameter of the tube was 12 mm. The inert gas supply pipe 20 was arranged so that the axial direction K was parallel to the width direction of the film 1. Compressed air that had been subjected to ion generation treatment by corona discharge was introduced into the inert gas supply pipe 20.

<Evaluation>
The obtained film roll was evaluated for winding deviation and black band.

(Winding misalignment)
The roll deviation of the film roll was measured. For example, as shown in FIG. 6, when the winding deviation occurred, the winding deviation x of the film roll 10 was measured.
○: x was less than 1 mm;
Δ: x is 1 mm or more and less than 3 mm, and there was no practical problem;
X: x was 3 mm or more, and there was a problem in practical use.

(Black band)
The obtained film roll was subjected to an accelerated test for long-term storage. Specifically, the film roll was heated from room temperature (23 ° C.) to 65 ° C. at a rate of temperature increase of 21 ° C./day for 2 days, then kept at 65 ° C. and allowed to stand for 7 days. The temperature was returned to room temperature over 2 days.
The film roll subjected to the acceleration test was unwound and a film of about 300 m from the core was visually observed.
○: No deformation;
Δ: Although there was some deformation, there was no practical problem;
X: There was a deformation and there was a problem in practical use.

(Thickness of entrained air layer)
The obtained film roll was subjected to an acceleration test similar to the acceleration test at the time of evaluation of the black band.
The thickness d of the entrained air layer in the film roll subjected to the acceleration test was measured by the method described above.

[Examples 2 to 10 / Comparative Examples 1 to 4]
In the winding process, the height h of the knurling part is adjusted to a predetermined value, the wind speed V of the compressed air 12, the distance L from the gas supply pipe 20 to the winding start point 13, and the film 1 is wound around the winding core 5. A film roll was produced and evaluated in the same manner as in Example 1 except that the tension until the film was taken was adjusted to a predetermined value.
In Comparative Example 1, no knurling part was formed.
In Comparative Example 2, the knurling part was formed only at one end in the width direction of the film.

(A) is a schematic sketch of an example of the film roll of this invention, (B) is the schematic of the cross section which bisects a film roll perpendicularly | vertically with respect to the width direction TD in (A), and its main point. FIG. It is a schematic sectional drawing for demonstrating the measuring method of the thickness of an inert gas layer, and shows the schematic of the cross section which bisects a film roll perpendicularly. (A)-(B) is an expanded sectional view of the width direction end of the film in one Embodiment used in this invention, and shows a vertical sectional view with respect to a film moving direction. It is a vertical sectional view to the width direction of the film for explaining the manufacturing method of the film roll concerning the present invention. It is a schematic sketch showing an example of an inert gas supply pipe. It is a schematic sketch of the film roll for demonstrating the evaluation method of winding deviation.

Explanation of symbols

  1: polymer film, 1a: polymer film just before winding, 1b: outermost polymer film already wound around the core, 4: inert gas layer, 5: core, 6: knurling part, 10: Film roll, 12: Inert gas, 13: Winding start point, 20: Inert gas supply means, 21: Supply port, 50: Cross section that bisects the film roll perpendicularly to the width direction.

Claims (14)

  In a cross section in which a polymer film having a knurling portion at both ends in the width direction is wound in a multilayer shape around the core, and the film roll is divided into two equal parts perpendicular to the width direction A film roll having an inert gas layer between the polymer films, wherein the thickness d of the inert gas layer is 3.0 to 5.0 μm on average.   The film roll according to claim 1, wherein the inert gas is air, nitrogen, helium, or a mixed gas thereof.   The film roll according to claim 1 or 2, wherein the polymer film is an optical film containing a cellulose resin.   The film roll according to any one of claims 1 to 3, wherein the polymer film has a coat layer.   The film roll in any one of Claims 1-4 in which the knurling part which a polymer film has in the width direction both ends is formed continuously in the moving direction of a polymer film.   The film roll according to any one of claims 1 to 5, wherein the winding length of the polymer film is 1900 to 5200 m, the lateral length is 1330 to 1490 mm, and the thickness is 30 to 100 µm.   In the step of winding a polymer film having a knurling portion at both ends in the width direction around the core in a multilayered manner, the polymer film just before being wound and the outermost polymer film already wound around the core; A method for producing a film roll, wherein an inert gas is supplied between the polymer films and an inert gas is fed between the polymer films. An inert gas is supplied by an inert gas supply means;
The wind speed V of the inert gas is 0.8 to 5.5 m / second,
The distance L from the inert gas supply means to the winding start point of the polymer film is 10 to 340 mm,
The manufacturing method of the film roll of Claim 7 whose tension F until a polymer film is wound up by a winding core is 130-450 N / m.   The method for producing a film roll according to claim 7 or 8, wherein the inert gas is air, nitrogen, helium, or a mixed gas thereof.   The method for producing a film roll according to any one of claims 7 to 9, wherein the inert gas is subjected to ion generation treatment.   The method for producing a film roll according to any one of claims 7 to 10, wherein the polymer film is an optical film containing a cellulose resin.   The manufacturing method of the film roll in any one of Claims 7-11 in which a polymer film has a coating layer.   The manufacturing method of the film roll in any one of Claims 7-12 in which the knurling part which a polymer film has in the width direction both ends is formed continuously in the moving direction of a polymer film.   The method for producing a film roll according to any one of claims 7 to 13, wherein the winding length of the polymer film is 1900 to 5200 m, the lateral length is 1330 to 1490 mm, and the thickness is 30 to 100 µm.

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