WO2021250904A1 - Film and method for producing same, and roll body and method for producing same - Google Patents

Abstract

The film of the present invention has belt-like convex parts at both end parts in the width direction. When the maximum height of the convex part is denoted by Tmax and when the area of the convex part located above the midpoint (Tmax/2) of the convex part with respect to the maximum height Tmax of the convex part is denoted by S1, and the area of the convex part below said midpoint is denoted by S2, S1 and S2 satisfy formula (1) below.　Formula (1): 0.6 ≤ S1/S2 ≤ 0.95

Description

Film and its manufacturing method, roll body and its manufacturing method

The present invention relates to a film and a method for producing the same, a roll body and the method for producing the same.

A resin film containing a cycloolefin resin or a (meth) acrylic resin as a main component has good transparency and dimensional stability, and is therefore used as an optical film such as a polarizing plate protective film.

From the viewpoint of handleability and manufacturing efficiency, such an optical film is usually stored or transported as a roll body obtained by winding a strip-shaped film into a roll shape.

In such a roll body, in order to suppress quality failure due to sticking between films during storage or transportation, both ends in the width direction of the film are usually subjected to uneven processing called embossing. (See, for example, Patent Document 1). On the other hand, the embossed portion formed by the embossing process is easily crushed, and the sticking between the films may not be sufficiently suppressed.

On the other hand, a method of forming convex portions (knurled portions) by coating on both ends in the width direction of the film is also known (see, for example, Patent Document 2). It is said that the knurled portion formed by coating has higher strength than the embossed portion and is not easily crushed, so that the adhesion between the films can be satisfactorily suppressed.

Japanese Unexamined Patent Publication No. 2012-118238 Japanese Unexamined Patent Publication No. 2012-206312

In Patent Document 2, the shape of the knurled portion 2 (convex portion) in the cross section along the width direction of the film 1 is rectangular (see FIG. 6). Since the surface of such a knurled portion is in close contact with the back surface of the overlapping films when wound into a roll, air can be reliably contained between the films at the time of winding.

However, if an impact is applied from the outside during the winding of the film, the air stored between the films is released at once, and there is a problem that winding misalignment (deformation of the roll) and sticking between the films are likely to occur. there were. When such winding misalignment or sticking of the film occurs, the optical characteristics tend to deteriorate, especially in the optical film. Therefore, at the time of winding the film, it is desired that the air is appropriately contained between the films and the air is released appropriately.

The present invention has been made in view of the above circumstances, and is capable of producing a film capable of suppressing winding misalignment and sticking when an impact is applied from the outside while appropriately containing air between the films. It is an object of the present invention to provide a method, a roll body and a method for producing the same.

The above problem can be solved by the following configuration.

The film of the present invention is a film having band-shaped convex portions at both ends in the width direction, and when the maximum height of the convex portions is Tmax, the midpoint of the convex portions (Tmax) with respect to the maximum height Tmax of the convex portions. / 2) When the region of the convex portion above the middle point is S1 and the region of the convex portion below the midpoint is S2, S1 and S2 satisfy the following equation (1).
Equation (1): 0.6 ≤ S1 / S2 ≤ 0.95

The method for producing a film of the present invention is a method for producing a film having band-shaped protrusions at both ends in the width direction, and 1) a step of casting a first resin composition to obtain a band-shaped film base. 2) The step of casting the second resin composition on both ends of the surface of the strip-shaped film base in the width direction to form the strip-shaped convex portion, and during the casting of the step 2). The ratio η2 / η1 of the viscosity η2 of the second resin composition to the viscosity η1 of the first resin composition at the time of casting in the step 1) is 0.00003 to 0.02.

The roll body of the present invention is a roll body obtained by winding a strip-shaped film having strip-shaped protrusions at both ends in the width direction, and when the maximum height of the convex portions is Tmax, the maximum height of the convex portions is taken. When the convex region S1 above the midpoint of the convex portion (Tmax / 2) with respect to Tmax and the region of the convex portion below the midpoint are S2, S1 and S2 satisfy the following equation (1). A roll body characterized by.
Equation (1): 0.6 ≤ S1 / S2 ≤ 0.95

The method for producing a roll body of the present invention is a method for producing a roll body in which a band-shaped film having band-shaped protrusions at both ends in the width direction is wound, and 1) the first resin composition is cast by casting. A step of obtaining a strip-shaped film base and 2) a step of casting a second resin composition on both ends of the surface of the strip-shaped film base in the width direction to form the strip-shaped convex portion are included. The ratio η2 / η1 of the viscosity η2 of the second resin composition at the time of casting in the step 2) to the viscosity η1 of the first resin composition at the time of casting in the step 1) is 0.00003 to 0. It is 0.02.

According to the present invention, it is possible to provide a roll body of a film capable of suppressing winding misalignment and sticking when an impact is applied from the outside while appropriately containing air between the films, and a method for producing the same. can.

1A is a plan view of a strip-shaped film according to the present embodiment, and FIG. 1B is a sectional view taken along line 1B-1B of FIG. 1A. FIG. 2 is an enlarged view of the convex portion of FIG. 1B. 3A is a plan view of the strip-shaped film in another embodiment, and FIG. 3B is a sectional view taken along line 3B-3B of FIG. 3A. 4A is a plan view of the strip-shaped film in another embodiment, and FIG. 4B is a sectional view taken along line 4B-4B of FIG. 4A. 5A to 5C are cross-sectional views showing the shape of the convex portion according to another embodiment. FIG. 6 is a cross-sectional view of a conventional strip-shaped film.

The present inventors make it possible to form an appropriate gap between the convex portion and the back surface of the film base when the strip-shaped film is wound into a roll shape; specifically, in the width direction of the film. In the cross section, the strip-shaped film is wound into a roll by adjusting the ratio S1 / S2 of the area S1 of the upper half region of the convex portion to the area S2 of the lower half region to be 0.95 or less. It was found that it is possible to suppress winding misalignment and sticking at the time.

By forming an appropriate gap between the convex portion and the back surface of the film base in this way, it is possible to wind the film while appropriately discharging the air while appropriately containing air between the films. .. As a result, it is considered that the air excessively accumulated between the films is not discharged at once at the time of winding, and the winding deviation and deformation due to the air are not discharged at once.

The adjustment of S1 / S2 can be performed by any method, for example, the viscosity and the resin concentration of the resin composition for forming the convex portion, the drying rate (or the solidification rate) of the resin composition, and the surface of the film base. It can be adjusted by processing. For example, from the viewpoint of setting S1 / S2 to 0.95 or less, it is preferable to reduce the contact angle of the resin composition for forming the convex portion with the film base; for that purpose, the viscosity of the resin composition or the like. It is preferable to lower the resin concentration or increase the drying rate (or solidification rate) of the resin composition.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

The film of the present invention may be a strip-shaped film or a sheet-fed film cut out from the strip-shaped film. First, an example in which the film is a strip-shaped film (roll body of the strip-shaped film) will be described.

1. 1. Roll body of film The roll body of the present invention is a strip-shaped film wound in a roll shape along a direction orthogonal to the width direction thereof.

FIG. 1A is a plan view of the strip-shaped film in the present embodiment, and FIG. 1B is a sectional view taken along line 1B-1B of FIG. 1A. FIG. 2 is an enlarged view of the convex portion 12 of FIG. 1B. In FIG. 1B, hatching of the cross section is omitted for the sake of clarity.

As shown in FIGS. 1A and 1B, the strip-shaped film 10 has strip-shaped protrusions 12 at both ends in the width direction. In the present embodiment, the strip-shaped film 10 has a film base 11 and convex portions 12 provided at both ends in the width direction thereof.

1-1. Film base 11
The film base 11 is preferably a resin film, and more preferably a resin film that can be used as an optical film.

(resin)
The resin contained in the film base 11 (resin film) is preferably a thermoplastic resin. The thermoplastic resin may be any one suitable for an optical film and is not particularly limited, and examples thereof include a cycloolefin resin, a (meth) acrylic resin, a polyimide, a cellulose ester, a polyester, and a polycarbonate. Among them, cycloolefin resin, (meth) acrylic resin and cellulose ester are preferable from the viewpoint of having good transparency, and cycloolefin resin and (meth) acrylic resin are preferable from the viewpoint of further having low hygroscopicity (high dimensional stability). Is more preferable.

(Cycloolefin resin)
The cycloolefin resin is preferably a polymer containing a structural unit derived from a norbornene-based monomer. The norbornene-based monomer may be any compound having a norbornene skeleton, and is not particularly limited. However, when a film is formed by a solution casting method, a norbornene-based monomer having a polar group is preferable.

The norbornene-based monomer having a polar group is preferably represented by the formula (1).

In the formula (1), R ¹ to R ⁴ independently represent a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a polar group, respectively. At ^{least one of R 1} to R ⁴ is a polar group.

A polar group is a functional group whose polarization is caused by an atom having a high electronegativity such as an oxygen atom, a sulfur atom and a nitrogen atom. Examples of such polar groups include a carboxy group, a hydroxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, an amino group, an amide group, a cyano group, and these groups are attached via a linking group such as an alkylene group. Groups etc. are included. Of these, a carboxy group, a hydroxy group, an alkoxycarbonyl group or an aryloxycarbonyl group is preferable, and an alkoxycarbonyl group and an aryloxycarbonyl group are more preferable from the viewpoint of ensuring solubility at the time of solution casting.

From the viewpoint of facilitating the localization of polar groups on the film surface, it is preferable that R ¹ and R ² are hydrogen atoms and R ³ and R ⁴ are groups other than hydrogen atoms.

P represents an integer of 0 to 2.

Examples of the monomer represented by the formula (1) include the following.

The content of the structural unit derived from the norbornene-based monomer having a polar group can be 50 to 100% by mass with respect to all the structural units constituting the cycloolefin resin.

The cycloolefin resin having a polar group may further contain a structural unit derived from a copolymerizable monomer copolymerizable with the norbornene-based monomer having the polar group, if necessary.

Examples of copolymerizable monomers include norbornene-based monomers having no polar group and monomers having no norbornene skeleton. Examples of monomers having no norbornene skeleton include open-ring copolymerizable copolymerizable monomers (with norbornene-based monomers having polar groups) and (with norbornene-based monomers having polar groups). A copolymerizable monomer capable of addition copolymerization is included.

Examples of ring-opening copolymerizable copolymerizable monomers include cycloolefins that do not have a norbornene skeleton, such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.

Examples of copolymerizable monomers include unsaturated double bond-containing compounds, vinyl cyclic hydrocarbon monomers, and (meth) acrylic acid esters. Examples of unsaturated double bond-containing compounds are olefin compounds having 2 to 8 carbon atoms, and examples thereof include ethylene, propylene, and butene. Examples of vinyl-based cyclic hydrocarbon monomers include vinyl cyclopentene-based monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene. Examples of (meth) acrylic acid esters include (meth) acrylic acid alkyl esters having 1 to 20 carbon atoms such as methyl (meth) acrylate, 2-ethylhexyl (meth) acrylic acid, and cyclohexyl (meth) acrylic acid. included.

The weight average molecular weight (Mw) of the cycloolefin resin is preferably 20,000 to 300,000. When the Mw of the cycloolefin resin is within the above range, the film-forming property is not easily impaired while imparting sufficient mechanical strength to the film. From the above viewpoint, the Mw of the cycloolefin resin is more preferably 40,000 to 200,000.

The Mw of the cycloolefin resin can be measured in terms of polystyrene by gel permeation chromatography (GPC). Specifically, it can be measured using a Tosoh HLC8220GPC) and a column (Tosoh TSK-GEL G6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL series).

The glass transition temperature (Tg) of the cycloolefin resin is usually 110 ° C. or higher, preferably 110 to 350 ° C., more preferably 120 to 250 ° C., and particularly preferably 120 to 220 ° C. .. When the Tg of the cycloolefin resin is 110 ° C. or higher, deformation due to use under high temperature conditions and secondary processing such as coating and printing is suppressed, which is preferable. Further, when Tg is 350 ° C. or lower, resin deterioration due to heat during molding or molding is suppressed, which is preferable.

The Tg of the cycloolefin resin can be measured according to JIS K7121-2012 or ASTM D3418-82 using DSC (Differential Scanning Colorimetry).

((Meta) acrylic resin)
The (meth) acrylic resin is a homopolymer of a (meth) acrylic acid ester, or a copolymer of a (meth) acrylic acid ester and a copolymerizable monomer copolymerizable therewith. The (meth) acrylic acid ester is preferably methyl methacrylate.

The copolymerizable monomer may be a copolymerizable monomer copolymerizable with methyl methacrylate, may be a copolymerizable monomer having a ring structure, or may be a copolymerizable monomer having no ring structure. It may be.

An example of a copolymerized monomer having a ring structure is
It has an alicyclic such as (meth) dicyclopentanyl acrylate, (meth) isobornyl acrylate, (meth) adamantyl acrylate, (meth) cyclohexyl acrylate, and six-membered ring lactone (meth) acrylate ester (meth). Acrylic acid ester;
Vinyls having an alicyclic such as vinylcyclohexane;
Vinyls with aromatic rings such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, α-methylstyrene; and N-phenylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-cyclohexylmaleimide , NO-Chlorophenylmaleimide and other maleimides (compounds having an imide ring) are included.

An example of a copolymerized monomer having no ring structure is
Ethyl (meth) acrylate, propyl (meth) acrylate, butyl (meth) acrylate, 2-hydroxyethyl (meth) acrylate, hexyl (meth) acrylate, 2-ethylhexyl (meth) acrylate, (meth) (Meta) acrylic acid alkyl ester having 2 to 20 carbon atoms such as n-octyl acrylate;
Unsaturated nitriles such as (meth) acrylonitrile;
Unsaturated carboxylic acids such as (meth) acrylic acid, crotonic acid, (meth) acrylic acid;
Olefins such as vinyl acetate, ethylene and propylene;
Vinyl halides such as vinyl chloride, vinylidene chloride and vinylidene fluoride;
Includes (meth) acrylamides such as (meth) acrylamide, methyl (meth) acrylamide, ethyl (meth) acrylamide, and propyl (meth) acrylamide.

The copolymerizable monomer may be one kind or a combination of two or more kinds.

The Mw of the (meth) acrylic resin is preferably 400,000 to 3 million. When Mw is in the above range, sufficient mechanical strength (toughness) is imparted to the film, and film forming property and drying property are not easily impaired. From the above viewpoint, the Mw of the (meth) acrylic resin is more preferably 500,000 to 2,000,000. The Mw of the (meth) acrylic resin can be measured by the same method as described above.

The Tg of the (meth) acrylic resin is preferably 90 ° C. or higher. When the Tg is 90 ° C. or higher, not only the heat resistance of the film can be improved, but also the drying property at the time of film formation can be easily improved. From the viewpoint of making the toughness of the film less likely to be impaired, the Tg of the (meth) acrylic resin is more preferably 100 to 150 ° C. The Tg of the (meth) acrylic resin can be measured by the same method as described above.

(Cellulose ester)
Cellulose ester is a compound obtained by esterifying cellulose with a carboxylic acid.

The total degree of substitution of the acyl group of the cellulose ester is preferably 2 to 3, and more preferably 2.2 to 2.6. The acyl group can be an acetyl group, a propionyl group or both. The degree of substitution of the acyl group of the cellulose ester can be measured by the method specified in ASTM-D817-96.

Examples of cellulose esters include cellulose triacetate and cellulose acetate propionate.

The Mw of the cellulose ester is preferably 100,000 to 500,000, more preferably 150,000 to 300,000 in order to obtain a certain level of mechanical strength or higher. Mw can be measured by the same method as described above.

The Tg of the cellulose ester is usually preferably 140 to 200 ° C, more preferably 160 to 190 ° C. Tg can be measured by the same method as described above.

The content of the resin is preferably 60% by mass or more, and may be 70 to 100% by mass with respect to the film base 11.

(Fine particles)
The film base 11 may further contain fine particles (matting agent), if necessary. Thereby, an appropriate slipperiness can be imparted to the surface of the resin film.

The fine particles may be inorganic fine particles or organic fine particles.

Examples of inorganic fine particles include silica particles. The average primary particle size of the silica particles is not particularly limited, but is preferably, for example, 5 to 100 nm, and more preferably 10 to 50 nm.

As an example of the organic fine particles, it is preferable that the polymer fine particles have a refractive index difference of 0.01 or less from the resin. Examples of such organic fine particles include (meth) acrylic acid esters, vinyl esters, styrenes, and olefins from the viewpoint of having high affinity with resins and easily adjusting the refractive index within the above range. A copolymer containing structural units selected from the above group is preferable, and a copolymer containing (meth) acrylic acid esters and structural units derived from styrenes is more preferable, and the copolymer is derived from (meth) acrylic acid esters. A copolymer containing a structural unit, a structural unit derived from styrenes, and a structural unit derived from a polyfunctional monomer is more preferable.

The glass transition temperature (Tg) of the organic fine particles is preferably 80 ° C. or higher. The glass transition temperature (Tg) of the organic fine particles can be measured according to JISK7121-2012 or ASTMD3418-82 in the same manner as described above.

The average particle size of the organic fine particles is 0.01 to 0.4 μm. When the average particle size of the organic fine particles is 0.01 μm or more, unevenness of an appropriate size can be formed on the surface of the obtained film, so that it is easy to impart slipperiness. It is easy to suppress the increase of internal haze. From the above viewpoint, the average particle size of the organic fine particles is more preferably 0.07 to 0.28 μm.

The average primary particle diameter of the inorganic fine particles and the organic fine particles can be measured by the following procedure.
1) TEM observe the cross section of the film parallel to the in-plane slow phase axis. The observation area is the same as described above.
2) The primary particle diameters of any 10 inorganic fine particles or organic fine particles in the obtained TEM image are measured, and the average value thereof is defined as the "average primary particle diameter".

[Physical characteristics]
The thickness of the film base 11 is constant. That is, since the film base 11 is not embossed, it does not have a thin portion formed by being crushed by an emboss roller. The thickness of the film base 11 is not particularly limited, but is preferably 3 to 40 μm, more preferably 5 to 30 μm, and even more preferably 10 to 20 μm.

The length (winding length) of the film base 11 is not particularly limited, but is preferably 2000 to 15000 m, more preferably 3000 to 12000 m. The width of the film base 11 is not particularly limited, but is preferably 950 to 3000 mm.

(Phase difference Ro and Rt)
The film base 11 preferably has a phase difference according to the required optical characteristics. From the viewpoint of using the protective film as a retardation film for IPS mode, for example, the in-plane retardation Ro and the thickness direction retardation Rt measured at a wavelength of 550 nm and 23 ° C. 55% RH have the following equations, respectively. It is preferable to meet.
｜ Ro ｜ ≦ 10nm
｜ Rt ｜ ≦ 10nm

Ro and Rt are defined by the following equations, respectively.
Equation (I): Ro = (nx-ny) × d
Equation (II): Rt = ((nx + ny) /2-nz) × d
(During the ceremony,
nx represents the refractive index of the film base 11 in the in-plane slow phase axial direction (direction in which the refractive index is maximized).
ny represents the refractive index in the direction orthogonal to the in-plane slow phase axis of the film base 11.
nz represents the refractive index of the film base 11 in the thickness direction.
d represents the thickness (nm) of the film base 11. )

The in-plane slow phase axis of the film base 11 can be confirmed by an automatic birefringence meter Axoscan (AxoScan Mueller Matrix Polarimeter: manufactured by Axometrics).

Ro and Rt can be measured by the following methods.
1) The film base 11 is humidity-controlled for 24 hours in an environment of 23 ° C. and 55% RH. The average refractive index of the film base 11 is measured with an Abbe refractometer, and the thickness d is measured with a commercially available micrometer.
2) The retardation Ro and Rt of the film base 11 after humidity control at a measurement wavelength of 550 nm were measured at 23 ° C. and 55% RH using an automatic birefringence meter Axoscan (AxoScan Mueller Matrix Matrix Polarimeter). Measure in the environment of.

(Internal haze)
The internal haze of the film base 11 is preferably 1.0% or less, more preferably 0.1% or less, still more preferably 0.05% or less. The internal haze of the film base 11 can be measured in accordance with JIS K-6714 using a haze meter (HGM-2DP, Suga Test Instruments) at 25 ° C. and 60% RH for a sample of 40 mm × 80 mm.

1-2. Convex part 12
The convex portion 12 is a knurling portion obtained by applying a resin composition to both ends of the surface of the film base portion 11 in the width direction.

The convex portions 12 are arranged in strips along the longitudinal direction of the film base 11 at both ends of the film base 11 in the width direction (see FIG. 1A). The "strip shape" includes not only a continuously extending shape but also an intermittently extending shape. That is, the convex portions 12 may be continuously arranged in a band shape or may be intermittently arranged in a band shape. In this embodiment, the convex portions 12 are continuously arranged (see FIG. 1A). The convex portion 12 may be integrated with the film base portion 11 or may be a separate body.

In the cross section along the width direction of the film 10 (cross section orthogonal to the extending direction of the convex portion 12), when the maximum height of the convex portion 12 is Tmax, the height of Tmax / 2 in the area of the convex portion 12 The area of the region farther from the film base 11 (the region above the midpoint Tmax / 2 of the convex portion 12) is S1 (upper part of FIG. 2), and the region closer to the film base 11 than the height of Tmax / 2 (the upper part of FIG. 2). When the area of the region below the midpoint of the convex portion 12 is S2 (lower portion of FIG. 2), S1 is smaller than S2. Specifically, it is preferable that S1 and S2 satisfy the following formula (1).
Equation (1): 0.6 ≤ S1 / S2 ≤ 0.95

When S1 / S2 is 0.6 or more, the contact area between the convex portion 12 and the back surface of the film base 11 can be secured, so that air can be appropriately stored between the overlapping film bases 11. When S1 / S2 is 0.95 or less, the convex portion 12 and the back surface of the film base 11 do not come into close contact with each other, and an appropriate gap can be formed. As a result, when the film is wound, the air can be appropriately evacuated while the air is contained between the overlapping film bases 11. As a result, it is possible to suppress excessive inclusion of air between the overlapping film bases 11, so that when an impact or the like is applied from the outside, the air accumulated between the film bases 11 is released at once. It is possible to suppress winding misalignment and sticking. From the same viewpoint, it is more preferable to satisfy 0.7 ≦ S1 / S2 ≦ 0.9.

The height of the convex portion 12 means the height from the surface of the film base 11 (the height of the surface of the film base 11 in the normal direction).

The sum of the areas S1 and S2 of the convex portion 12 is preferably 0.0006 ~ 0.07 mm ^2, and more preferably 0.0013 ~ 0.03 mm ^2. When the total of the areas S1 and S2 of the convex portion 12 is not less than the lower limit value, winding deviation is likely to occur, and when it is not more than the upper limit value, air is likely to be excessively contained. When the convex portion 12 is formed intermittently, the total of the above S1 and S2 is calculated as an average value of the total of S1 and S2 measured for each of the plurality of convex portions 12.

The areas S1 and S2 of the convex portion 12, the maximum height Tmax of the convex portion, and the maximum width Wmax in the cross section along the width direction of the film 10 can be measured by using a laser microscope. As the laser microscope, for example, a laser Microscope VK-X1000 manufactured by KEYENCE Corporation can be used. Specifically, the areas S1 and S2 of the convex portion 12 are measured with the upper half of the convex portion 12 in a region of 100 mm in the length direction of the film and 15 mm in the width direction of the film centered on one row of the convex portions. The area of the lower half can be measured with a laser microscope, and the average value thereof can be obtained as "areas S1 and S2 of the convex portion 12".
When there are a plurality of rows (lines) of the convex portions 12, the values for one row (line) of the convex portions 12 are shown. Further, in the case of dispenser coating or intermittent coating, the average value of the measured values for the plurality of convex portions 12 existing in the above region is used.

The ratio (%) of the total area of the convex portions (S1 + S2) to the area of the film base in the cross section in the width direction of the optical film is not particularly limited, but is preferably 0.005 to 0.06%, for example, 0. It is preferably 0.01 to 0.04%. When there are a plurality of convex portions in the cross section in the width direction of the optical film, it means the ratio of the total area of these portions to the area of the film base.

The shape of the convex portion 12 is such that an appropriate gap can be formed between the convex portion 12 and the back surface of the film base 11 when the film 10 is wound, specifically, S1 / S2 satisfy the above range. Any shape may be used, and the shape is not particularly limited.

For example, the height of the central portion of the convex portion 12 (in the width direction of the film base 11) may be higher than the height of both ends of the convex portion 12 (see FIG. 2 and FIG. 5A described later). It may be the same as the height of both ends of the protrusion 12 (see FIG. 5B described later), or may be lower than the height of both ends of the convex portion 12 (see FIG. 5C described later). Above all, it is preferable that the height of the central portion of the convex portion 12 is higher than the height of both ends of the convex portion 12 or is the same as the height of both ends of the convex portion 12. In the present embodiment, the height of the central portion of the convex portion 12 is higher than the height of both end portions of the convex portion 12 (see FIG. 2).

Specifically, in the cross section along the width direction of the film 10, the shape of the convex portion 12 may be either a circular segment or a polygon. The bow shape is a shape in which both ends of an arc or an elliptical arc are connected by a straight line, and examples thereof include a semicircle and a semi-elliptical shape. Examples of polygons include trapezoids (see FIG. 5B below) and staircase shapes (see FIG. 5A below).

The maximum height Tmax of the convex portion 12 is not particularly limited, but is preferably 0.8 to 35%, more preferably 1.0 to 15%, and 2.5 to 25% of the thickness of the film base 11. It is more preferably 7.0%. Specifically, the maximum height Tmax of the convex portion 12 is preferably 0.3 to 4.0 μm, and more preferably 0.5 to 2.0 μm.

The maximum width of the convex portion 12 in the width direction of the film base 11 is not particularly limited, but is preferably 0.05 to 5%, preferably 0.05 to 3% of the width of the film base 11. More preferably, it is more preferably 0.05 to 1%. Specifically, the maximum width Wmax of the convex portion 12 is preferably 0.5 to 50 mm, more preferably 1 to 30 mm.

The position of the apex of the convex portion 12 in the width direction of the film 10 is not particularly limited, but is preferably within the range of 0.3 Wmax to 0.7 Wmax from one end of the convex portion 12 in the width direction.

The convex portion 12 is obtained from the second resin composition described later, and contains a resin.

As the resin contained in the convex portion 12, the same resin as that contained in the film base portion 11 can be used. That is, the resin contained in the film base 11 and the resin contained in the convex portion 12 may be of the same type or may be different types. Above all, from the viewpoint of enhancing the adhesion between the convex portion 12 and the film base portion 11, it is preferable that the resin contained in the film base portion 11 and the resin contained in the convex portion 12 are of the same type. That is, when the resin contained in the film base 11 is a cycloolefin resin, it is preferable that the resin contained in the convex portion 12 is also a cycloolefin resin.

The Mw of the resin contained in the convex portion 12 is preferably lower than the Mw of the resin contained in the film base 11. Specifically, the Mw of the cycloolefin resin contained in the convex portion 12 is preferably 10,000 to 50,000. When the Mw of the cycloolefin resin is within the above range, it is difficult to excessively increase the viscosity of the knurling solution, and it is easy to adjust the maximum height Tmax of the convex portion within the above range. From the above viewpoint, the Mw of the cycloolefin resin is more preferably 20,000 to 40,000. The Mw of the cycloolefin resin can be measured by the same method as described above.

The content of the resin is not particularly limited, but is preferably 60% by mass or more, and more preferably 70 to 100% by mass with respect to the entire convex portion 12.

The convex portion 12 may further contain the same components (for example, fine particles) as the film base 11 if necessary. However, when the film 10 is wound, the content of the fine particles in the convex portion 12 is the content of the fine particles in the film base 11 from the viewpoint of making it difficult to slip between the convex portion 12 and the back surface of the film base 11 and making it easy to appropriately adhere to the convex portion 12. It is preferably less than the content of fine particles, and more preferably free of fine particles.

2. 2. Method for Producing Roll Body The roll body of the present invention comprises 1) a step of casting the first resin composition onto a support to obtain a strip-shaped film base 11, and 2) both ends of the strip-shaped film base 11 in the width direction. It can be obtained through a step of casting a second resin composition on the portion to form a convex portion.

1) Step of Obtaining Film Base 11 The first resin composition is cast to obtain a strip-shaped film base 11.

The casting of the first resin composition may be carried out by a melt casting method or a solution casting method. Above all, from the viewpoint that a high molecular weight resin can be used, it is preferable that the first resin composition is cast by a solution casting method.

That is, the film base 11 has 1A) a step of obtaining a first resin composition (dope) and 1B) a step of casting the obtained dope onto a support, drying and peeling it off to obtain a film-like substance. And 1C) can be obtained through the steps of stretching the obtained film-like material.

Regarding the step 1A), the resin is dissolved in a solvent to prepare a first resin composition.

The solvent used contains at least an organic solvent (good solvent) capable of dissolving the resin. Examples of good solvents include chlorine-based organic solvents such as dichloromethane; non-chlorine-based organic solvents such as methyl acetate, ethyl acetate, acetone and tetrahydrofuran. Of these, methylene chloride is preferable.

The solvent used may further contain a poor solvent. Examples of poor solvents include straight-chain or branched-chain aliphatic alcohols having 1 to 4 carbon atoms. The higher the proportion of alcohol in the dope, the easier it is for the film to gel and the easier it is to peel off from the metal support. Examples of the linear or branched aliphatic alcohol having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Of these, methanol and ethanol are preferable from the viewpoint of stability and drying property.

Regarding the step 1B), the obtained first resin composition is then cast on the support. The casting of the first resin composition can be carried out by discharging from a casting die. The temperature of the first resin composition at the time of casting is usually 15 to 30 ° C, preferably room temperature (23 ° C).

Next, the solvent in the first resin composition cast on the support is appropriately evaporated (after being dried) and then peeled off from the support to obtain a film-like substance.

The residual solvent amount of the first resin composition at the time of peeling is, for example, preferably 25% by mass or more, more preferably 30 to 37% by mass, and further preferably 30 to 35% by mass. When the amount of the residual solvent at the time of peeling is 25% by mass or more, the solvent is likely to be volatilized at once from the film-like substance after peeling. Further, when the amount of the residual solvent at the time of peeling is 37% by mass or less, it is possible to suppress the film-like material from being excessively stretched due to peeling.

The amount of residual solvent in the first resin composition at the time of peeling is defined by the following formula. The same applies to the following.
Residual solvent amount (% by mass) = (mass before heat treatment of first resin composition-mass after heat treatment of first resin composition) / mass after heat treatment of first resin composition × 100
The heat treatment for measuring the amount of residual solvent means a heat treatment at 140 ° C. for 15 minutes.

The amount of residual solvent at the time of peeling can be adjusted by adjusting the drying temperature and drying time of the first resin composition on the support, the temperature of the support, and the like.

About step 1C) Then, the obtained film-like material is dried. Drying may be performed in one step or in multiple steps. Further, the drying may be carried out while stretching, if necessary.

Stretching may be performed according to the required optical characteristics, and it is preferable to stretch in at least one direction, and stretching in two directions orthogonal to each other (for example, the width direction (TD direction) of the film-like material and orthogonal to it. Biaxial stretching in the transport direction (MD direction)) may be performed.

The draw ratio can be 1.01 to 2 times, for example, from the viewpoint of using it as a retardation film for IPS. The stretch ratio is defined as (the size of the film after stretching in the stretching direction) / (the size of the film before stretching in the stretching direction). When biaxial stretching is performed, it is preferable to set the stretching ratio in each of the TD direction and the MD direction.

The in-plane slow phase axial direction of the film (the direction in which the refractive index is maximum in the plane) is usually the direction in which the draw ratio is maximum.

The drying temperature (stretching temperature) during stretching is preferably (Tg-65) ° C. to (Tg + 60) ° C., preferably (Tg-50) ° C. to (Tg + 50) ° C., where Tg is the glass transition temperature of the resin. Is more preferable. When the stretching temperature is above a certain level, the solvent is easily volatilized appropriately, so that the stretching tension can be easily adjusted within an appropriate range.

The stretching temperature is (a) when drying with a non-contact heating type such as a tenter stretching machine, the ambient temperature such as the temperature inside the stretching machine or the hot air temperature, and (b) when drying with a contact heating type such as a hot roller. , The temperature of the contact heating portion, or (c) the surface temperature of the film-like material (surface to be dried) can be specified.

The amount of residual solvent in the film-like material at the start of stretching is preferably about the same as the amount of residual solvent in the film-like material at the time of peeling, for example, preferably 20 to 30% by mass, and 25 to 30% by mass. % Is more preferable.

Stretching of the film-like object in the TD direction (width direction) can be performed by, for example, fixing both ends of the film-like object with clips or pins and widening the distance between the clips or pins in the traveling direction (tenter method). Stretching of the film-like material in the MD direction can be performed, for example, by a method (roll method) in which a peripheral speed difference is applied to a plurality of rolls and the roll peripheral speed difference is used between them.

From the viewpoint of further reducing the amount of residual solvent, it is preferable to further dry (post-dry) the film-like substance obtained after stretching. For example, it is preferable to further dry the film-like material obtained after stretching while transporting it with a roll or the like (with a constant tension applied).

The drying temperature (drying temperature when not stretched or drying temperature after stretching) is preferably (Tg-30) to (Tg + 30) ° C., where Tg is the glass transition temperature of the resin, and is preferably (Tg-20). It is more preferable that the temperature is ~ Tg ° C. When the drying temperature is above a certain level, it is easy to increase the volatilization rate of the solvent from the film-like material after stretching, so it is easy to increase the drying efficiency. .. The drying temperature can be specified in the same manner as described above.

2) About the step of forming the convex portion Next, the second resin composition is cast on both ends in the width direction of the obtained film base portion 11 to form the convex portion.

The casting of the second resin composition may be a melt casting method or a solution casting method. From the viewpoint of increasing the production efficiency, when the first resin composition is formed by the solution casting method in the step 1) above, it is preferable that the second resin composition is also formed by the solution casting method.

That is, the convex portion 12 can be formed by applying a second resin composition (knurling solution) containing a resin and a solvent to both ends in the width direction of the film base portion 11 and then drying the film base portion 11.

(Second resin composition)
As the resin contained in the second resin composition, the same resin as that contained in the dope can be used.

The solvent contained in the second resin composition contains at least an organic solvent (good solvent) capable of dissolving the resin. Examples of good solvents include chlorine-based organic solvents such as methylene chloride; non-chlorine-based organic solvents such as methyl acetate, ethyl acetate, acetone, tetrahydrofuran, cyclopentanone and toluene. Of these, methylene chloride, cyclopentanone, and toluene are preferable from the viewpoint of easily dissolving the cycloolefin resin. Among them, ketones such as cyclopentanone and methylene chloride are more preferable from the viewpoint that the volatilization rate is high because the saturated vapor pressure is high and the S1 / S2 of the convex portion can be easily adjusted to the above range.

The solvent contained in the second resin composition may further contain a poor solvent. As the poor solvent, the same solvent as the poor solvent contained in the dope can be used.

The viscosity of the second resin composition (knurling solution) at the time of casting is the viscosity of the first resin composition (dope) at the time of casting in the step 1) above from the viewpoint of adjusting S1 / S2 of the convex portion to the above range. It is preferably lower than. Specifically, the ratio η2 / η1 of the viscosity η2 of the second resin composition at the time of casting in the step 2) to the viscosity η1 of the first resin composition at the time of casting in the step 1) is 0.00003. It is preferably ~ 0.01. When η2 / η1 is 0.00003 or more, S1 / S2 of the convex portion 12 tends to be 0.6 or more, and when it is 0.02 or less, S1 / S2 of the convex portion 12 tends to be 0.9 or less.

The viscosity η1 of the first resin composition at the time of casting is preferably, for example, 10,000 to 100,000 mPa · s, and the viscosity η2 of the second resin composition is preferably 1 to 300 mPa · s. The viscosity can be measured with a viscometer (for example, a viscometer RE-80L manufactured by Toki Sangyo Co., Ltd.).

In the solution casting method, the viscosity at the time of casting can be adjusted, for example, by the resin concentration or the molecular weight of the resin; in the melt casting method, it is preferable to adjust the viscosity by, for example, the melting temperature or the molecular weight of the resin.

In the solution casting method, the resin concentration of the second resin composition is preferably lower than the resin concentration of the first resin composition, and is preferably 50% by mass or less of the resin concentration of the first resin composition. Specifically, the resin concentration of the second resin composition is preferably more than 2% by mass and 10% by mass or less, and more preferably 3 to 7% by mass.

(assignment)
The second resin composition can be applied by any method, for example, casting with a die (preferably a reduced pressure die), coating with a dispenser, or the like.

When using a decompression die, the slit gap may be adjusted according to the thickness of the convex portion, and the slit width may be adjusted according to the width of the convex portion. The gap of the slit is preferably 100 to 300 μm, for example, and the width of the slit is preferably 3 to 20 mm, for example. When a dispenser is used, the discharge amount is preferably 1 to 100 μg / shot, and the discharge pitch is preferably 0.2 to 30 mm, for example.

The temperature of the second resin composition at the time of casting is, for example, 10 to 30 ° C, preferably room temperature (23 ° C).

(Dry)
The second resin composition can be dried by any method, for example, hot air drying, heat drying by electromagnetic waves (for example, heat drying by an infrared (IR) heater), or the like. From the viewpoint of adjusting S1 / S2 of the convex portion 12 to the above range, the drying speed is preferably high, and heat drying by electromagnetic waves is more preferable.

From the viewpoint of adjusting S1 / S2 of the convex portion 12 to the above range, it is preferable that the second resin composition is dried as soon as possible after being applied to the film base portion 11. Although it depends on the composition of the resin composition, the drying is preferably performed within 5 seconds after the application, for example.

The drying temperature is not particularly limited, but is preferably high from the viewpoint of adjusting the convex portion 12 to the above range for S1 / S2. Specifically, the drying temperature is preferably 40 to (Tg-20) ° C., preferably 80 to (Tg-10) ° C., where the glass transition temperature of the resin contained in the second resin composition is Tg. It is more preferable to do it in. Specifically, the temperature is preferably 40 to 120 ° C, more preferably 80 to 100 ° C.

Then, the obtained film 10 is wound into a roll along the longitudinal direction.

3) Winding step The obtained film base 11 is wound in the longitudinal direction (direction orthogonal to the width direction) of the film 10 using a winder. Thereby, a film wound in a roll shape around the winding core, that is, a roll body of the film 10 can be obtained.

The winding method is not particularly limited, and may be a constant torque method, a constant tension method, a taper tension method, or the like.

The winding tension when winding the film base 11 can be about 50 to 170 N. As described above, the longer the winding length, the more likely it is that the air stored between the films is released at once when the film is wound into a roll shape, resulting in winding misalignment or sticking. Even in such a case, by adjusting S1 / S2 of the convex portion 12 to the above range, it is possible to wind up while appropriately discharging excess air (while appropriately storing air between the films). It is possible to suppress winding misalignment and sticking.

When the film 10 is used, the formed portion of the convex portion 12 is removed, and the film 10 is used as an optical film for a display device such as a liquid crystal display device or an organic EL display device. Examples of the optical film include a polarizing plate protective film (including a retardation film and a brightness improving film), a transparent base film, and a light diffusing film. Above all, the film 10 is preferably used as a polarizing plate protective film.

3. 3. Film and Method for Producing The Film As described above, the film of the present invention may be cut out from a roll of the strip-shaped film 10, and has strip-shaped protrusions at both ends in the width direction.

Specifically, the film has a film base (corresponding to the film base 11) and strip-shaped convex portions (corresponding to the convex 12) provided at both ends in the width direction of the surface thereof. Then, in the cross section of the film orthogonal to the extending direction of the strip-shaped convex portion, S1 and S2 of the convex portion satisfy the relationship of the above formula (1) and satisfy 0.7 ≦ S1 / S2 ≦ 0.9. Is more preferable.

In the cross section of the film orthogonal to the extending direction of the band-shaped convex portion, the shape of the convex portion, the total area of S1 and S2, the maximum height Tmax and the maximum width Wmax of the convex portion, and the total area of S1 and S2 of the film base. The ratio to the area is as described above. Further, the shape of the film base 11 (without the recess) and the thickness of the film base in the cross section of the film orthogonal to the extending direction of the band-shaped convex portion are also as described above.

The film of the roll body does not include, for example, the winding step of 3) above, or further includes a step of cutting out a strip-shaped film unwound from the roll body after the winding step of 3) above. It can be manufactured in the same manner as the manufacturing method.

[Modification example]
In the above embodiment, the convex portion 12 is continuously arranged along the longitudinal direction of the film base portion 11, but the present invention is not limited to this. For example, the convex portion 12 may be arranged intermittently along the longitudinal direction of the film base portion 11.

FIG. 3A is a plan view of the strip-shaped film in another embodiment, and FIG. 3B is a sectional view taken along line 3B-3B of FIG. 3A. 4A is a plan view of the strip-shaped film in another embodiment, and FIG. 4B is a sectional view taken along line 4B-4B of FIG. 4A.

That is, the convex portion 12 may be arranged intermittently along the longitudinal direction of the film base portion 11 (see FIG. 3A). The length of the convex portion 12 (the length in the longitudinal direction of the film base portion 11) can be about 0.04 to 10.0% with respect to the width of the film base portion 11. The gap between the plurality of strip-shaped convex portions 12 can be about 0.02 to 1.0% with respect to the length of the convex portions 12.

Further, the convex portion 12 may be arranged in an island shape along the longitudinal direction of the film base portion 11 (see FIG. 4A). Such a convex portion 12 can be formed by intermittently discharging with a dispenser. The discharge conditions may be as described above.

Further, in the above embodiment, an example is shown in which the shape of the convex portion 12 is the shape shown in FIG. 2 (see FIG. 2), but the present invention is not limited to this.

FIGS. 5A to 5C are views showing an example of deformation of the shape of the convex portion 12 in the cross section along the width direction of the film 10. That is, the shape of the convex portion 12 may be stepped (see FIG. 5A) or trapezoidal (see FIG. 5B). Further, the height of the central portion of the convex portion 12 may be lower than the height of both ends of the convex portion 12 (see FIG. 5C).

Further, in the above embodiment, the example in which the convex portions 12 are arranged one by one at both ends in the width direction of the film base portion 11 is shown, but the present invention is not limited to this, and a plurality of convex portions 12 may be arranged one by one.

Further, in the above embodiment, the example in which the convex portion 12 is arranged on only one surface of the film base portion 11 is shown, but the present invention is not limited to this, and the convex portion 12 may be arranged on both surfaces.

Further, in the above embodiment, an example (solution casting method) in which the convex portion 12 is formed by applying a knurling solution containing a resin and a solvent and then drying the convex portion 12 is shown, but the present invention is not limited to this, and the convex portion 12 is melted. After the resin composition is applied, it may be formed by cooling and solidifying to form (melt casting method).

That is, in the melt casting method, the roll body has 1) a step of casting the melted first resin composition and then cooling and solidifying to obtain a strip-shaped film base, and 2) a width of the strip-shaped film base 11. It can be obtained through a step of applying a melted second resin composition to both ends in the direction and then cooling and solidifying to form a convex portion. In this case, the first resin composition and the second resin composition are the same as the above-mentioned first resin composition and second resin composition, respectively, except that they do not contain a solvent.

The melt viscosity of the second resin composition at the time of casting is preferably lower than the melt viscosity of the first resin composition at the time of film formation of the film base 11. The melt viscosity can be adjusted by adjusting the melt temperature, the weight average molecular weight of the resin, and the like. For example, from the viewpoint of adjusting S1 / S2 to the above range, the Mw of the resin contained in the second resin composition is preferably lower than the Mw of the resin of the first resin composition, and the second resin composition at the time of casting is preferable. The melting temperature of the material may be higher than the melting viscosity of the first resin composition at the time of film formation of the film base 11.

Further, in the above embodiment, as a method for adjusting the shape of the convex portion 12, a method for adjusting the viscosity or the resin concentration of the second resin composition, the application method, the drying conditions, and the like is shown, but the method is not limited thereto. For example, after casting the second resin composition, both ends may be cut (cut) for adjustment, or the film base 11 may be surface-treated (hydrophilicized or the like) for adjustment.

Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited thereto.

1. 1. Preparation of cycloolefin resin film (film base) <Preparation of cycloolefin resin film 1>
(Preparation of fine particle dispersion)
10 parts by mass of R218 and 80 parts by mass of ethanol were stirred and mixed with a dissolver for 30 minutes, and then dispersed with menton gorin. 80 parts by mass of dichloromethane is added to the obtained solution with stirring, and the mixture is stirred and mixed with a dissolver for 30 minutes, and then filtered through a filter (Advantech Toyo Co., Ltd .: polypropylene wind cartridge filter TCW-PPS-1N). , A fine particle dispersion was obtained.

(Preparation of doping)
Then, a dope having the following composition was prepared. First, methylene chloride was added to the pressure dissolution tank, and then the following cycloolefin resin was added while stirring. Then, the fine particle dispersion liquid prepared above was further added thereto, heated to 60 ° C., and completely dissolved while stirring. The heating temperature was raised from room temperature at 5 ° C./min, dissolved in 30 minutes, and then lowered at 3 ° C./min. This was converted, using SHP150 manufactured by (Corporation) Rokitekuno, filtered flow rate 300L ^{/ m} 2 · h, and filtered through a filtration pressure 1.0 × ¹⁰ 6 Pa, to obtain a dope.
JSR G7810 (cycloolefin resin containing structural units represented by the following formula, weight average molecular weight 40,000, glass transition temperature 170 ° C.): 100 parts by mass Methylene chloride: 150 parts by mass Ethanol: 20 parts by mass Fine particle dispersion: 150 parts by mass

(Film formation)
The obtained dope was uniformly cast on the stainless belt support of the endless belt casting device at room temperature (23 ° C.). The temperature of the stainless steel belt was 28 ° C., and the transport speed of the stainless steel belt was 20 m / min. Next, the solvent is evaporated on the stainless belt support until the amount of the residual solvent in the cast film becomes 25% by mass, and then the solvent is peeled off from the stainless belt support to form the film. Got
Then, the obtained film-like substance was stretched 1.2 times in the width direction under the condition of (Tg-15) ° C. (Tg: Tg of cycloolefin resin) with a tenter.
Then, while transporting the stretched film-like material by a roll, it is further dried at (Tg-10) ° C. until the amount of residual solvent measured by the above-mentioned headspace gas chromatography is within the range of 30 to 600 mass ppm. After that, the end portion sandwiched between the tenter clips was slit by a laser cutter and wound up to obtain a cycloolefin resin film having a width of 1450 mm, a length of 4000 m and a thickness of 20 μm.

<Preparation of cycloolefin resin films 2 to 4>
Cycloolefin resin films 2 to 4 were obtained in the same manner as in cycloolefin resin film 1 except that the draw ratio was changed so that the thickness of the film was 10 μm, 40 μm, and 60 μm.

2. 2. Preparation of solution for forming protrusions (second resin composition) <Preparation of solutions 1 to 3, 6 to 9 and 11 to 14>
The resin shown in Table 1 and the solvent were mixed so as to have the resin concentration shown in Table 1 to obtain solutions 1 to 3, 6 to 9 and 11 to 14 for forming convex portions. Of these, silica particles (R218) were added to the solution 12 in the same amount as the silica particles in the film.

<Preparation of solution 4>
Polymethylmethacrylate (PMMA, weight average molecular weight 1 million) was dissolved in the solvent shown in Table 1 at 35 ° C. to obtain a convex portion forming solution 4.

<Preparation of solutions 5 and 10>
Cellulose triacetate (TAC, weight average molecular weight 130,000) was dissolved in the solvent shown in Table 1 to obtain solutions 5 and 10 for forming protrusions.

Table 1 shows the compositions and physical properties of the obtained convex protrusion forming solutions 1 to 14.

3. 3. Preparation of roll body <Examples 1 to 6, 8, 10, 11, 16 and Comparative Examples 1, 3, 5 and 6>
After the solution shown in Table 2 was continuously applied to both ends of the prepared cycloolefin resin film in the width direction from a reduced pressure die (die in the comparative example) under the conditions of Table 2 at room temperature (23 ° C.). , Dried to form the protrusions shown in FIGS. 1A and 1B.

<Example 9>
The convex portions shown in FIGS. 3A and 3B were formed in the same manner as in Example 1 except that the solution shown in Table 2 was intermittently applied under the conditions shown in Table 2. The length of the convex portions (in the length direction of the cycloolefin resin film) was 100 mm, and the pitch between the convex portions was 10 mm.

<Examples 7 and 13 to 15>
The solution shown in Table 2 was applied to both ends of the prepared cycloolefin resin film in the width direction with a dispenser under the conditions shown in the same table, and then dried to form convex portions shown in FIGS. 4A and 4B. .. In Example 12, convex portions were formed on both sides of the film. The dispenser was made by using SUPER HI JET manufactured by Musashi Engineering Co., Ltd.

<Example 12>
The convex portion was formed in the same manner as in Example 3 except that the coating shape of the convex portion was changed as shown in Table 2.

<Comparative Example 2>
Both ends of the cycloolefin resin film produced above in the width direction on one side were embossed to form an embossed portion. The embossing was performed by pressurizing a metal ring having a heated uneven pattern (a shape in which nine irregularities are continuous in the width direction). The processing pressure of the metal ring was 200 kPa, and the temperature was 230 ° C. The obtained embossed portion had a thin portion thinner than the thickness of the central portion in the width direction of the film. The area ratio S1'/ S2' of the portion above the thin portion (the portion corresponding to the convex portion) was measured and found to be 0.48.

<Comparative Example 4>
A laser beam was irradiated to both ends in the width direction of one side of the prepared cycloolefin resin film with a laser marker to form a laser irradiation portion. The laser irradiation portion had a thin portion thinner than the thickness of the central portion in the width direction of the film. The area ratio S1'/ S2' of the portion above the thin portion (the portion corresponding to the convex portion) was measured and found to be 0.47.

<Evaluation>
(Viscosity ratio)
The viscosities of the dope for the film when the rolls were produced in Examples 1 to 16 and Comparative Examples 1 to 6 at the time of casting and the viscosities of the solution for forming the convex portion at the time of casting were the viscosities manufactured by Toki Sangyo Co., Ltd., respectively. It was measured by a total of RE-80L. The viscosity of the dope (first resin composition) at the time of film formation (23 ° C.) is 27,000 mPa · s, and the viscosity of the convex portion forming solution (second resin composition) satisfies the viscosity ratio in Table 3. It was viscosity.

Further, the physical characteristics of the convex portion of the roll body, the shape of the roll body, and the presence or absence of deformation of the film obtained in Examples 1 to 16 and Comparative Examples 1 to 6 were evaluated by the following methods.

<Physical characteristics of convex parts>
The areas S1 and S2 of the convex portions, the maximum height Tmax of the convex portions, and the maximum width Wmax in the widthwise cross section of the film were measured using a laser microscope. As a laser microscope, a laser Microscope VK-X1000 manufactured by KEYENCE was used.
Specifically, the maximum height and the maximum width of the convex portion are measured in a region of 100 mm in the length direction of the film and a width of 15 mm centered on one row of the convex portions, and the average value thereof is set to "convex portion". Maximum height Tmax and maximum width Wmax ”.
Similarly, for a region of 100 mm in the length direction of the film and a width of 15 mm centered on one row of convex portions, the lower half area and the upper half of the convex portion area with the height of Tmax / 2 as a boundary. The area was measured with a laser microscope, and the average value thereof was defined as "areas S1 and S2 of the convex portion 12". When there are a plurality of convex rows (lines), the values for one convex row (line) are shown. Further, in the case of dispenser coating or intermittent coating, the average value of the measured values for the plurality of convex portions existing in the above region was used.

(Shape of roll body)
The shape of the roll body was formed by Keyence's XG-X2900, CA-HL08MX (line scan camera) and CA-DZW50X (pattern illumination). Specifically, when observing the surface of the roll body, the area of deformation having a size of 200 μm × 200 μm or more is measured and totaled, and the area of the outermost surface of the roll body (the area of one roll of the outermost film) is measured. Judgment was made by area ratio (%).
⊚: less than 0.3% ○: 0.3% or more and less than 0.5% ○ △: 0.5% or more and less than 1.0% △: less than 1.0% less than 2.0% ×: 2.0% If it is above 〇 △, it is judged to be good.

(Deformation of film)
The deformation of the film was evaluated by feeding out a roll body and counting the number of deformation failures by XG-X2900, CA-HL08MX (line scan camera) and CA-DZW50X (pattern illumination) at a line speed of 5 m / min. The number of deformation failures was counted as one deformation having a size of 100 μm × 100 μm or more. Then, the deformation of the film was evaluated based on the following criteria.
⊚: 10 pieces / less than 1000 m ○: 50 pieces / less than 1000 m ○ Δ: 100 pieces / less than 1000 m Δ: 200 pieces / less than 1000 m ×: 200 pieces / 1000 m or more 〇 △ or more is judged to be good.

Table 2 shows the preparation conditions for the rolls of Examples 1 to 16 and Comparative Examples 1 to 6, and Table 3 shows the evaluation results.

As shown in Table 3, it can be seen that the roll bodies of Examples 1 to 16 have less winding deviation and sticking, and less change in the shape of the roll body. It can also be seen that the film is less deformed.

In particular, it can be seen that by lowering the resin concentration of the convex portion forming solution, S1 / S2 can be appropriately reduced, and the deformation of the roll body and the deformation of the film can be further reduced (comparison between Examples 3 and 9). , Comparison of Examples 8 and 11).

Further, it can be seen that by setting the solvent composition of the convex portion forming solution to ketones such as cyclopentane, S1 / S2 can be appropriately reduced, and the deformation of the roll body and the deformation of the film can be further reduced (implementation). Comparison of Examples 2, 3 and 10). It is considered that this is because the saturated vapor pressure is high and the evaporation rate is high.

Further, it can be seen that the deformation of the roll body and the deformation of the film can be reduced by applying the solution for forming the convex portion with the dispenser (comparison between Examples 1 and 14 to 15). It is considered that this is because the application of the dispenser can reduce the curl of the film base due to the heat during drying than the application of the vacuum die.

On the other hand, in Comparative Examples 1 and 3 in which S1 / S2 exceeded 0.95, the roll body was deformed and the film was deformed. This is because when winding, the convex part is too close to the back surface of the film base and air does not escape, and as a result, the accumulated air is periodically released, causing winding misalignment and film sticking. It is thought that this is due to the fact that it occurs.

Further, it can be seen that the roll body of Comparative Example 2 which has been embossed and the roll body of Comparative Example 4 in which the convex portion is formed by laser irradiation both cause deformation of the roll body and deformation of the film. It is probable that this is because the area S2 is low, so that the embossed portion or the laser irradiation portion is crushed by stress, the roll shape cannot be maintained, and sticking or the like occurs.

<Examples 17 to 21>
A roll body was formed in the same manner as in Example 3 except that the slit gap was changed as shown in Table 4.

<Examples 22 to 24>
A roll body was formed in the same manner as in Example 7 except that the number of rows (number of lines) of the convex portions and the pitch between the convex portions (in the length direction of the film) were changed as shown in Table 4.

<Examples 25 to 27>
A roll body was formed in the same manner as in Example 3 except that the winding length of the film was changed as shown in Table 4.

<Examples 28 to 30>
A roll body was formed in the same manner as in Example 3 except that the thickness of the film was changed as shown in Table 4.

<Example 31>
A roll body was formed in the same manner as in Example 3 except that the discharge width was changed as shown in Table 4.

<Examples 32 and 33>
A roll body was formed in the same manner as in Example 7 except that the discharge amount and the pitch between the protrusions (in the length direction of the film) were changed as shown in Table 4.

Then, the shape of the roll body and the deformation of the film of Examples 17 to 33 were evaluated in the same manner as described above.

Table 4 shows the preparation conditions for the rolls of Examples 17 to 33, and Table 5 shows the evaluation results.

As shown in Table 5, it can be seen that the roll bodies of Examples 17 to 33 have less winding deviation and sticking, and less change in the shape of the roll body.

According to the present invention, a roll body of a film which is not easily crushed by a winding pressure and which can suppress winding misalignment and sticking when an impact is applied from the outside by maintaining an appropriate amount of air between the films, and a method for manufacturing the same. Can be provided.

10 Strip-shaped film 11 Film base 12 Convex part

Claims (15)

1. A film having strip-shaped protrusions at both ends in the width direction.
   When the maximum height of the convex portion is Tmax, the convex portion region S1 above the convex midpoint (Tmax / 2) with respect to the maximum height Tmax of the convex portion, and the convex portion below the midpoint. A film characterized in that S1 and S2 satisfy the following formula (1) when the region is S2.
   Equation (1): 0.6 ≤ S1 / S2 ≤ 0.95
2. The height of the central portion of the convex portion is higher than the height of both ends of the convex portion, or is the same as the height of both ends of the convex portion.
   The film according to claim 1.
3. In the cross section of the film orthogonal to the extending direction of the strip-shaped convex portion,
   The shape of the convex portion is a bow shape or a trapezoidal shape.
   The film according to claim 1 or 2.
4. Tmax is 0.3-4.0 μm,
   The film according to any one of claims 1 to 3.
5. The film has a film base and strip-shaped protrusions arranged at both ends of the surface of the film base in the width direction.
   The film base has no recesses.
   The film according to any one of claims 1 to 4.
6. The thickness of the film base is 3 to 40 μm.
   The film according to claim 5.
7. The film base is a resin film.
   The film according to any one of claims 5 or 6.
8. The resin film is an optical film.
   The film according to claim 7.
9. A method for manufacturing a film having band-shaped protrusions at both ends in the width direction.
   1) A step of casting the first resin composition to obtain a strip-shaped film base, and
   2) A step of casting a second resin composition on both ends of the surface of the strip-shaped film base in the width direction to form the strip-shaped convex portions is included.
   The ratio η2 / η1 of the viscosity η2 of the second resin composition at the time of casting in the step 2) to the viscosity η1 of the first resin composition at the time of casting in the step 1) is 0.00003 to. 0.02,
   How to make a film.
10. Each of the first resin composition and the second resin composition contains a resin and a solvent, and contains a resin and a solvent.
    The resin concentration of the second resin composition is lower than the resin concentration of the first resin composition.
    The film manufacturing method according to claim 9.
11. The resin concentration of the second resin composition is more than 2% by mass and 10% by mass or less.
    The method for producing a film according to claim 10.
12. The thickness of the film base is 3 to 40 μm.
    The film manufacturing method according to any one of claims 9 to 11.
13. The film base is an optical film.
    The method for producing a film according to any one of claims 9 to 12.
14. A roll body obtained by winding a strip-shaped film having strip-shaped protrusions at both ends in the width direction.
    When the maximum height of the convex portion is Tmax, the convex portion region S1 above the convex midpoint (Tmax / 2) with respect to the maximum height Tmax of the convex portion, and the convex portion below the midpoint. A roll body characterized in that S1 and S2 satisfy the following formula (1) when the region is S2.
    Equation (1): 0.6 ≤ S1 / S2 ≤ 0.95
15. A method for manufacturing a roll body in which a strip-shaped film having strip-shaped protrusions at both ends in the width direction is wound.
    1) A step of casting the first resin composition to obtain a strip-shaped film base, and
    2) A step of casting the second resin composition on both ends of the surface of the strip-shaped film base in the width direction to form the strip-shaped convex portions.
    Including
    The ratio η2 / η1 of the viscosity η2 of the second resin composition at the time of casting in the step 2) to the viscosity η1 of the first resin composition at the time of casting in the step 1) is 0.00003 to. 0.02,
    A method for manufacturing a roll body.

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