Film and method for producing the same, roll and method for producing the same

Abstract

The film of the present invention is a film having strip-shaped convex portions at both ends in the width direction. When the maximum height of the convex portion is set to Tmax, the convex portion area located above the midpoint (Tmax / 2) of the convex portion relative to the maximum height Tmax of the convex portion is set to S1, and the convex portion area located below the midpoint is set to S2, S1 and S2 satisfy the following formula (1): Formula (1): 0.6≤S1 / S2≤0.95.

Description

Technical Field

[0001] The present invention relates to a film and a method for producing the same, a roll and a method for producing the same. Background Art

[0002] Resin films containing cycloolefin resins, (meth)acrylic resins, and the like as main components have excellent transparency and dimensional stability and are therefore used as optical films such as polarizing plate protective films.

[0003] From the viewpoint of handling properties and production efficiency, such an optical film is usually stored or transported as a roll body in which a strip-shaped film is wound into a roll shape.

[0004] In such a roll, in order to prevent quality problems such as adhesion of the films to each other during storage or transportation, a concave-convex process called embossing is usually applied to both ends of the film in the width direction (see, for example, Patent Document 1). On the other hand, the embossed portion formed by embossing is easily crushed, and sometimes it is not possible to fully prevent adhesion of the films to each other.

[0005] In contrast, there is also a known method of forming convex portions (knurled portions) by coating at both ends of the film in the width direction (see, for example, Patent Document 2). Since the knurled portions formed by coating are stronger than the embossed portions and are not easily crushed, the adhesion of the films to each other can be well suppressed.

[0006] Prior art literature

[0007] Patent Literature

[0008] Patent Document 1: Japanese Patent Application Publication No. 2012-118238

[0009] Patent Document 2: Japanese Patent Application Publication No. 2012-206312 Summary of the invention

[0010] 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 Figure 6 ). The surface of such a knurled portion is closely attached to the back surface of the overlapping film without a gap when it is wound into a roll, so that air can be reliably contained between the films when it is wound.

[0011] However, when an impact is applied from the outside during the film winding, the air accumulated between the films is released at once, which easily causes the problem of winding deviation (deformation of the roll) or adhesion of the films. If such winding deviation or adhesion of the films occurs, the optical properties are easily reduced, especially in optical films. Therefore, it is desired that when the film is wound, air is appropriately contained between the films and the air is appropriately discharged.

[0012] The present invention has been made in view of the above circumstances, and an object thereof is to provide a film and a method for producing the same, a roll and a method for producing the same, which can appropriately contain air between films and suppress winding deviation or sticking when an external impact is applied.

[0013] Solutions to Solve Problems

[0014] The above-mentioned problems can be solved by the following structure.

[0015] The film of the present invention is a film having strip-shaped convex portions at both ends in the width direction, and when the maximum height of the convex portion is set to Tmax, the area of ​​the convex portion located above the midpoint (Tmax / 2) of the convex portion relative to the maximum height Tmax of the convex portion is set to S1, and the area of ​​the convex portion located below the midpoint is set to S2, S1 and S2 satisfy the following formula (1):

[0016] Formula (1): 0.6≤S1 / S2≤0.95.

[0017] The method for manufacturing a film of the present invention is a method for manufacturing a film having band-shaped protrusions at both ends in the width direction, which comprises: 1) a process of casting a first resin composition to obtain a band-shaped film base, 2) a process of casting a second resin composition at both ends in the width direction of the surface of the band-shaped film base to form the band-shaped protrusions, wherein the ratio η2 / η1 of the viscosity η2 of the second resin composition during casting in the process 2) to the viscosity η1 of the first resin composition during casting in the process 1) is 0.00003 to 0.02.

[0018] The roll of the present invention is a roll of a film having strip-shaped convex portions at both ends in the width direction, and the roll is characterized in that, when the maximum height of the convex portion is set to Tmax, the convex portion area located above the convex portion midpoint (Tmax / 2) relative to the maximum height Tmax of the convex portion is set to S1, and the convex portion area located below the midpoint is set to S2, S1 and S2 satisfy the following formula (1):

[0019] Formula (1): 0.6≤S1 / S2≤0.95.

[0020] The roll manufacturing method of the present invention is a roll manufacturing method of a film having strip-shaped protrusions at both ends in the width direction, which includes: 1) a process of casting a first resin composition to obtain a strip-shaped film base, 2) a process of casting a second resin composition at both ends in the width direction of the surface of the strip-shaped film base to form the strip-shaped protrusions, and the ratio η2 / η1 of the viscosity η2 of the second resin composition during casting in the process 2) to the viscosity η1 of the first resin composition during casting in the process 1) is 0.00003 to 0.02.

[0021] Effects of the Invention

[0022] According to the present invention, it is possible to provide a film roll and a method for producing the same, which can appropriately contain air between films and suppress winding deviation or blocking when an external impact is applied. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1A is a top view of a strip-shaped film according to this embodiment. Figure 1B yes Figure 1A 1B-1B line cross-sectional view.

[0024] Figure 2 yes Figure 1B An enlarged view of the convex part.

[0025] Figure 3A is a top view of a strip-shaped film according to another embodiment. Figure 3B yes Figure 3A 3B-3B line cross-sectional view.

[0026] Figure 4A is a top view of a strip-shaped film according to another embodiment. Figure 4B yes Figure 4A 4B-4B line cross-sectional view.

[0027] Figure 5A to Figure 5C It is a cross-sectional view showing the shape of a convex portion according to another embodiment.

[0028] Figure 6 This is a cross-sectional view of a conventional strip-shaped film. DETAILED DESCRIPTION

[0029] The inventors have discovered that when a strip-shaped film is wound into a roll, an appropriate gap is formed between the protrusion and the back side of the base of the film; specifically, in the width-direction cross-section of the film, the ratio S1 / S2 of the area S1 of the upper half of the protrusion to the area S2 of the lower half is adjusted to be less than 0.95, thereby suppressing winding deviation or adhesion when the strip-shaped film is wound into a roll.

[0030] Thus, by forming a proper gap between the convex portion and the back side of the film base, the film can be properly contained with air between the films, and the film can be wound while the air is properly released. Thus, during winding, the air excessively retained between the films will not be released all at once, thereby suppressing winding deviation or deformation caused by the air.

[0031] S1 / S2 can be adjusted by any method, for example, by the viscosity or resin concentration of the resin composition used to form the protrusion, the drying speed (or curing speed) of the resin composition, the surface treatment of the film base, etc. For example, from the viewpoint of making S1 / S2 less than 0.95, it is preferred to reduce the contact angle of the resin composition used to form the protrusion to the film base; for this purpose, it is preferred to reduce the viscosity or resin concentration of the resin composition, or increase the drying speed (or curing speed) of the resin composition.

[0032] Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.

[0033] The film of the present invention may be a tape-shaped film or a sheet-shaped film cut out from a tape-shaped film. First, an example in which the film is a tape-shaped film (a roll of a tape-shaped film) will be described.

[0034] 1. Film roll

[0035] The roll of the present invention is a roll obtained by winding a strip-shaped film in a direction perpendicular to the width direction thereof.

[0036] Figure 1A is a top view of a strip-shaped film according to this embodiment. Figure 1B yes Figure 1A 1B-1B line cross-sectional view. Figure 2 yes Figure 1B It should be noted that in Figure 1B In the figure, the section lines are omitted for ease of observation.

[0037] like Figure 1A as well as Figure 1B As shown, the strip-shaped film 10 has strip-shaped convex portions 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.

[0038] 1-1. Film base 11

[0039] The film base 11 is preferably a resin film, and more preferably a resin film that can be used as an optical film.

[0040] (resin)

[0041] The resin contained in the film base 11 (resin film) is preferably a thermoplastic resin. The thermoplastic resin is not particularly limited as long as it is suitable for optical films, and examples thereof include cycloolefin resins, (meth) acrylic resins, polyimides, cellulose esters, polyesters, polycarbonates, and the like. Among them, cycloolefin resins, (meth) acrylic resins, and cellulose esters are preferred from the viewpoint of having good transparency, and cycloolefin resins and (meth) acrylic resins are more preferred from the viewpoint of having low hygroscopicity (high dimensional stability).

[0042] (Cycloolefin resin)

[0043] The cycloolefin resin is preferably a polymer containing a structural unit derived from a norbornene monomer. The norbornene monomer is not particularly limited as long as it is a compound having a norbornene skeleton, but when a film is formed by a solution casting method, a norbornene monomer having a polar group is preferred.

[0044] The norbornene-based monomer having a polar group is preferably represented by formula (1).

[0045] [Chemistry 1]

[0046] Mode(])

[0047]

[0048] In formula (1), R 1 ~R 4 Each independently represents a hydrogen atom, a hydrocarbon group having 1 to 30 carbon atoms, or a polar group. 1 ~R 4 At least one of the groups is a polar group.

[0049] Polar groups are functional groups polarized by highly electronegative atoms such as oxygen atoms, sulfur atoms, and nitrogen atoms. Examples of such polar groups include carboxyl, hydroxyl, alkoxycarbonyl, aryloxycarbonyl, amino, amide, cyano, and groups formed by combining these groups through linking groups such as alkylene. Among them, carboxyl, hydroxyl, alkoxycarbonyl, or aryloxycarbonyl is preferred, and alkoxycarbonyl and aryloxycarbonyl are more preferred from the viewpoint of ensuring solubility during solution casting.

[0050] From the viewpoint of making it easy to localize the polar group on the film surface, R 1 and R 2 is a hydrogen atom, and R 3 and R 4 A group other than a hydrogen atom.

[0051] p represents an integer from 0 to 2.

[0052] Examples of the monomer represented by formula (1) include the following.

[0053] [Chemistry 2]

[0054]

[0055] The content of the structural unit derived from the norbornene-based monomer having a polar group may be 50 to 100% by mass based on the total structural units constituting the cycloolefin resin.

[0056] 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 a polar group, as required.

[0057] Examples of copolymerizable monomers include norbornene monomers without polar groups and monomers without norbornene skeletons. Examples of monomers without norbornene skeletons include copolymerizable monomers that can be ring-opening copolymerized (with norbornene monomers with polar groups) and copolymerizable monomers that can be addition copolymerized (with norbornene monomers with polar groups).

[0058] Examples of the copolymerizable monomers capable of ring-opening copolymerization include cycloolefins not having a norbornene skeleton, such as cyclobutene, cyclopentene, cycloheptene, cyclooctene, and dicyclopentadiene.

[0059] Examples of copolymerizable monomers that can be addition-polymerized include compounds containing unsaturated double bonds, vinyl cyclic hydrocarbon monomers, and (meth)acrylates. Examples of compounds containing unsaturated double bonds include olefin compounds having 2 to 8 carbon atoms, and examples thereof include ethylene, propylene, and butene. Examples of vinyl cyclic hydrocarbon monomers include vinyl cyclopentene monomers such as 4-vinylcyclopentene and 2-methyl-4-isopropenylcyclopentene. Examples of (meth)acrylates include alkyl (meth)acrylates having 1 to 20 carbon atoms such as methyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and cyclohexyl (meth)acrylate.

[0060] 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, sufficient mechanical strength is imparted to the film while film forming properties are not easily impaired. From the above viewpoint, the Mw of the cycloolefin resin is more preferably 40,000 to 200,000.

[0061] The Mw of the cycloolefin resin can be measured in terms of polystyrene by gel permeation chromatography (GPC), specifically, using HLC8220GPC manufactured by Tosoh Corporation and a column (TSK-GEL G6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL manufactured by Tosoh Corporation in series).

[0062] 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 caused by secondary processing such as use, coating, and printing under high temperature conditions can be suppressed, so it is preferred. In addition, when the Tg is 350°C or lower, resin degradation caused by molding or heat during molding can be suppressed, so it is preferred.

[0063] The Tg of the cycloolefin resin can be measured using DSC (Differential Scanning Colorimetry) in accordance with JIS K 7121-2012 or ASTM D 3418-82.

[0064] ((Meth)acrylic resin)

[0065] 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.

[0066] The copolymerizable monomer may be any monomer copolymerizable with methyl methacrylate, and may be a copolymerizable monomer having a ring structure or a copolymerizable monomer not having a ring structure.

[0067] Examples of comonomers having a ring structure include:

[0068] (meth)acrylates having an alicyclic ring, such as dicyclopentanyl (meth)acrylate, isobornyl (meth)acrylate, adamantyl (meth)acrylate, cyclohexyl (meth)acrylate, and six-membered ring lactone (meth)acrylate;

[0069] Vinyls with aliphatic rings such as vinyl cyclohexane;

[0070] Vinyl groups having an aromatic ring, such as styrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, and α-methylstyrene; and

[0071] Maleimides (compounds having an imide ring) such as N-phenylmaleimide, N-ethylmaleimide, N-propylmaleimide, N-cyclohexylmaleimide, and N-o-chlorophenylmaleimide.

[0072] Examples of comonomers not having a ring structure include:

[0073] Alkyl (meth)acrylates having 2 to 20 carbon atoms, such as ethyl (meth)acrylate, propyl (meth)acrylate, butyl (meth)acrylate, 2-hydroxyethyl (meth)acrylate, hexyl (meth)acrylate, 2-ethylhexyl (meth)acrylate, and n-octyl (meth)acrylate;

[0074] Unsaturated nitriles such as (meth)acrylonitrile;

[0075] Unsaturated carboxylic acids such as (meth)acrylic acid, crotonic acid, (meth)acrylic acid;

[0076] Olefins such as vinyl acetate, ethylene or propylene;

[0077] Vinyl halides such as vinyl chloride, vinylidene chloride, and vinylidene fluoride;

[0078] (Meth)acrylamides such as (meth)acrylamide, methyl (meth)acrylamide, ethyl (meth)acrylamide, and propyl (meth)acrylamide.

[0079] The copolymerizable monomer may be used alone or in combination of two or more.

[0080] The Mw of the (meth) acrylic resin is preferably 400,000 to 3,000,000. If the Mw is within the above range, the film forming property and the drying property are not easily impaired while giving the film sufficient mechanical strength (toughness). 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 above.

[0081] 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 during film formation can be easily improved. From the viewpoint of not easily damaging the toughness of the film, 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 above.

[0082] (Cellulose ester)

[0083] Cellulose ester is a compound obtained by esterifying cellulose with carboxylic acid.

[0084] The total degree of substitution of acyl groups in cellulose ester is preferably 2 to 3, more preferably 2.2 to 2.6. The acyl group may be acetyl, propionyl, or both. The degree of substitution of acyl groups in cellulose ester can be measured by the method specified in ASTM-D817-96.

[0085] Examples of cellulose esters include cellulose triacetate and cellulose acetate propionate.

[0086] In order to obtain a certain level of mechanical strength or higher, the Mw of cellulose ester is preferably 100,000 to 500,000, more preferably 150,000 to 300,000. Mw can be measured by the same method as above.

[0087] The Tg of 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.

[0088] The content of the resin is preferably 60% by mass or more, and may be 70 to 100% by mass, based on the film base 11 .

[0089] (particle)

[0090] The film base 11 may contain fine particles (matting agent) as necessary. This can impart appropriate slip properties to the surface of the resin film.

[0091] The microparticles may be inorganic microparticles or organic microparticles.

[0092] Examples of inorganic fine particles include silica particles. The average primary particle size of the silica particles is not particularly limited, but is preferably 5 to 100 nm, and more preferably 10 to 50 nm, for example.

[0093] In the example of organic particles, polymer particles having a refractive index difference of 0.01 or less with the resin are preferred. In the example of such organic particles, from the viewpoint of high affinity with the resin and easy adjustment of the refractive index to the above range, copolymers containing structural units selected from the group consisting of (meth) acrylates, vinyl esters, styrenes and olefins are preferred, copolymers containing structural units from (meth) acrylates and styrenes are more preferred, and copolymers containing structural units from (meth) acrylates, structural units from styrenes and structural units from multifunctional monomers are further preferred.

[0094] The glass transition temperature (Tg) of the organic fine particles is preferably not less than 80° C. The glass transition temperature (Tg) of the organic fine particles can be measured in accordance with JIS K 7121-2012 or ASTM D 3418-82 as described above.

[0095] The average particle size of the organic particles is 0.01 to 0.4 μm. If the average particle size of the organic particles is 0.01 μm or more, it is possible to form appropriate size concavities and convexities on the surface of the obtained film, so that it is easy to impart slippage. If it is 0.4 μm or less, it is easy to suppress the increase of the internal haze of the film. From the above viewpoints, the average particle size of the organic particles is more preferably 0.07 to 0.28 μm.

[0096] The average primary particle size of the inorganic fine particles or organic fine particles can be measured by the following procedure.

[0097] 1) TEM observation of a cross section of the film parallel to the slow axis in the plane. The observation area is the same as above.

[0098] 2) The primary particle diameters of ten arbitrary inorganic fine particles or organic fine particles in the obtained TEM image are measured, and their average value is defined as the “average primary particle diameter”.

[0099] [Physical properties]

[0100] 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-walled portion formed by being crushed by the embossing 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 further preferably 10 to 20 μm.

[0101] 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.

[0102] (Phase difference Ro and Rt)

[0103] The film base 11 preferably has a phase difference corresponding to the required optical characteristics. For example, from the viewpoint of using as a phase difference film for IPS mode, the protective film preferably satisfies the following formulas for the in-plane phase difference Ro and the thickness phase difference Rt measured at a wavelength of 550nm, 23°C, and 55%RH.

[0104] |Ro|≤10nm

[0105] |Rt|≤10nm

[0106] Ro and Rt are defined by the following formulas:

[0107] Formula (I): Ro = (nx - ny) × d

[0108] Formula (II): Rt=((nx+ny) / 2-nz)×d

[0109] (In the formula,

[0110] nx represents the refractive index in the slow axis direction (the direction with the maximum refractive index) in the plane of the film base 11,

[0111] ny represents the refractive index in the direction perpendicular to the in-plane slow axis of the film base 11,

[0112] nz represents the refractive index in the thickness direction of the film base 11,

[0113] d represents the thickness of the thin film base 11 (nm).

[0114] The in-plane slow axis of the film base 11 can be confirmed by an automatic birefringence meter AxoScan (AxoScan Mueller Matrix Polarimeter: manufactured by Axometrics).

[0115] Ro and Rt can be measured by the following method.

[0116] 1) The film base 11 was humidified for 24 hours in an environment of 23° C. and 55% RH. The average refractive index of the film base 11 was measured using an Abbe refractometer, and the thickness d was measured using a commercially available micrometer.

[0117] 2) The retardation Ro and Rt of the film base 11 after humidity control at a measurement wavelength of 550 nm were measured using an automatic birefringence meter AxoScan (AxoScan Mueller Matrix Polarimeter: manufactured by Axometrics) in an environment of 23° C. and 55% RH.

[0118] (Internal haze)

[0119] The internal haze of the film base 11 is preferably 1.0% or less, more preferably 0.1% or less, and further preferably 0.05% or less. The internal haze of the film base 11 can be measured at 25°C and 60%RH using a haze meter (HGM-2DP, SUGA tester) on a sample of 40 mm×80 mm according to JIS K-6714.

[0120] 1-2.Protrusion 12

[0121] The protrusions 12 are knurled portions obtained by applying a resin composition to both ends in the width direction of the surface of the film base 11 .

[0122] The convex portions 12 are arranged in a strip shape along the longitudinal direction of the film base 11 at both ends in the width direction of the film base 11 (see Figure 1A ). The "belt-like" is not limited to a shape extending continuously, but also includes a shape extending intermittently. That is, the protrusion 12 may be arranged in a continuous belt shape or in a discontinuous belt shape. In this embodiment, the protrusion 12 is arranged continuously (see Figure 1A ). The protrusion 12 may be formed integrally with the film base 11 or may be formed separately.

[0123] In the cross section along the width direction of the film 10 (the cross section orthogonal to the extending direction of the convex portion 12), when the maximum height of the convex portion 12 is set to Tmax, the area of ​​the region of the convex portion 12 that is farther from the film base 11 than the height of Tmax / 2 (the region located above the midpoint Tmax / 2 of the convex portion 12) is set to S1 ( Figure 2 The area of ​​the region closer to the film base 11 than the height of Tmax / 2 (the region located below the midpoint of the convex portion 12) is set as S2 ( Figure 2 Specifically, it is preferred that S1 and S2 satisfy the following formula (1):

[0124] Formula (1): 0.6≤S1 / S2≤0.95.

[0125] When S1 / S2 is greater than 0.6, since the contact area between the protrusion 12 and the back side of the film base 11 can be ensured, air can be appropriately accumulated between the overlapping film bases 11. When S1 / S2 is greater than 0.95, the back side of the protrusion 12 and the film base 11 will not fit too closely, and an appropriate gap can be formed. Thus, when winding the film, even if air is contained between the overlapping film bases 11, the air can be appropriately discharged. Thus, since excessive air can be suppressed between the overlapping film bases 11, when an impact is applied from the outside, the air accumulated between the film bases 11 is released all at once, thereby suppressing the occurrence of winding deviation or adhesion. From the same point of view, it is more preferable to satisfy 0.7≤S1 / S2≤0.9.

[0126] The height of the convex portion 12 refers to the height from the surface of the film base 11 (the height in the normal direction of the surface of the film base 11 ).

[0127] The total area S1 and S2 of the convex portion 12 is preferably 0.0006 to 0.07 mm. 2 , more preferably 0.0013 to 0.03 mm 2 If the sum of the areas S1 and S2 of the convex portion 12 is greater than the lower limit, the winding is easily offset, and if it is less than the upper limit, it is easy to contain excessive air. It should be noted that when the convex portion 12 is formed intermittently, the sum of S1 and S2 is the sum of S1 and S2 measured for a plurality of convex portions 12 and calculated as their average value.

[0128] The areas S1 and S2 of the convex portion 12, the maximum height Tmax, and the maximum width Wmax of the convex portion in the cross section along the width direction of the film 10 can be measured using a laser microscope. As a laser microscope, for example, a laser microscope VK-X1000 manufactured by KEYENCE can be used. Specifically, the areas S1 and S2 of the convex portion 12 are measured by measuring the areas of the upper half and the lower half of the convex portion 12 respectively for an area of ​​100 mm in the length direction of the film and 15 mm in the width direction of the film centered on a row of convex portions using a laser microscope, and their average values ​​can be calculated as "areas S1 and S2 of the convex portion 12".

[0129] When there are a plurality of rows of projections 12, the value is shown for one row of projections 12. In the case of dispenser coating or intermittent coating, the average value of the measured values ​​of the plurality of projections 12 present in the above region is used.

[0130] The ratio (%) of the total area (S1+S2) of the convex portions in the cross section in the width direction of the optical film to the area of ​​the film base is not particularly limited, but is preferably 0.005 to 0.06%, more 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 refers to the ratio of the total area of ​​these convex portions to the area of ​​the film base.

[0131] The shape of the projection 12 is not particularly limited as long as it is a shape that can form an appropriate gap between the projection 12 and the back surface of the film base 11 when the film 10 is rolled up, specifically, a shape in which S1 / S2 satisfies the above range.

[0132] For example, the height of the center portion (in the width direction of the film base 11) of the protrusion 12 may be higher than the heights of both ends of the protrusion 12 (see Figure 2 or the following Figure 5A ), or the same height as the two ends of the convex portion 12 (see below). Figure 5B ), it may be lower than the height of both ends of the convex portion 12 (refer to the following Figure 5C ). It is preferred 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 this embodiment, the height of the central portion of the convex portion 12 is higher than the height of both ends of the convex portion 12 (refer to Figure 2 ).

[0133] Specifically, in the cross section along the width direction of the film 10, the shape of the protrusion 12 may be any of an arcuate (circular segment) and a polygon. The arcuate refers to a shape in which both ends of a circular arc or an elliptical arc are connected by a straight line, and examples thereof include a semicircle, a semiellipse, etc. Examples of polygons include a trapezoid (see below). Figure 5B ) and step shape (see below Figure 5A ).

[0134] The maximum height Tmax of the projection 12 is not particularly limited, but is preferably 0.8 to 35%, more preferably 1.0 to 15%, and further preferably 2.5 to 7.0% of the thickness of the film base 11. Specifically, the maximum height Tmax of the projection 12 is preferably 0.3 to 4.0 μm, and more preferably 0.5 to 2.0 μm.

[0135] The maximum width Wmax of the projection 12 in the width direction of the film base 11 is not particularly limited, but is preferably 0.05 to 5%, more preferably 0.05 to 3%, and even more preferably 0.05 to 1% of the width of the film base 11. Specifically, the maximum width Wmax of the projection 12 is preferably 0.5 to 50 mm, and more preferably 1 to 30 mm.

[0136] 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 located within a range of 0.3 Wmax to 0.7 Wmax from one end of the convex portion 12 in the width direction.

[0137] The projections 12 are obtained from a second resin composition described below and contain a resin.

[0138] The resin contained in the convex portion 12 may be the same resin as the resin contained in the film base 11. 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 of different types. However, from the viewpoint of improving the adhesion between the convex portion 12 and the film base 11, it is preferred that the resin contained in the film base 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 preferred that the resin contained in the convex portion 12 is also a cycloolefin resin.

[0139] The Mw of the resin contained in the protrusion 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 protrusion 12 is preferably 10,000 to 50,000. If 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 protrusion 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 using the same method as above.

[0140] The content of the resin is not particularly limited, but is preferably 60% by mass or more, more preferably 70 to 100% by mass, based on the entire convex portion 12 .

[0141] If necessary, the projections 12 may also contain the same components (e.g., microparticles) as the film base 11. However, from the viewpoint of making it difficult for the projections 12 to slide against the back of the film base 11 when the film 10 is rolled up and making it easy to fit appropriately, the content of microparticles in the projections 12 is preferably less than the content of microparticles in the film base 11, and more preferably, no microparticles are contained.

[0142] 2. Method for manufacturing the roll

[0143] The roll of the present invention can be obtained through the following steps: 1) the step of casting the first resin composition onto a support to obtain a strip-shaped film base 11; 2) the step of casting the second resin composition onto both ends of the strip-shaped film base 11 in the width direction to form convex portions.

[0144] 1) Step of obtaining the film base 11

[0145] The first resin composition is cast to obtain a tape-shaped film base 11 .

[0146] The first resin composition may be cast by melt casting or solution casting, but preferably by solution casting, because a high molecular weight resin can be used.

[0147] That is, the film base 11 can be obtained through the following steps: 1A) the step of obtaining a first resin composition (concentrate); 1B) the step of casting the obtained concentrate onto a support, drying and peeling it off to obtain a film-like object; 1C) the step of stretching the obtained film-like object.

[0148] About 1A) process

[0149] A resin is dissolved in a solvent to prepare a first resin composition.

[0150] The solvent used includes at least an organic solvent (good solvent) capable of dissolving the resin. Examples of good solvents include chlorine-based organic solvents such as dichloromethane, or non-chlorine-based organic solvents such as methyl acetate, ethyl acetate, acetone, and tetrahydrofuran. Among them, dichloromethane is preferred.

[0151] The solvent used may further include a poor solvent. Examples of poor solvents include linear or branched fatty alcohols having 1 to 4 carbon atoms. If the ratio of alcohol in the concentrated solution becomes high, the film-like substance is easily gelled and easily peeled off from the metal support. As linear or branched fatty alcohols having 1 to 4 carbon atoms, methanol, ethanol, n-propanol, isopropanol, n-butanol, sec-butanol, and tert-butanol can be cited. Among them, methanol and ethanol are preferred from the viewpoint of stability and dryness.

[0152] About 1B) process

[0153] Next, the obtained first resin composition is cast on a support. The first resin composition can be cast by ejecting from a casting die. The temperature of the first resin composition during casting is usually 15 to 30°C, preferably room temperature (23°C).

[0154] Next, after the solvent in the first resin composition cast on the support is appropriately evaporated (dried), the composition is peeled off from the support to obtain a film-like product.

[0155] The residual solvent amount of the first resin composition during stripping is, for example, preferably 25% by mass or more, more preferably 30 to 37% by mass, and further preferably 30 to 35% by mass. If the residual solvent amount during stripping is 25% by mass or more, it is easy to volatilize the solvent from the film after stripping. In addition, when the residual solvent amount during stripping is 37% by mass or less, it is possible to suppress the excessive elongation of the film caused by stripping.

[0156] The amount of the residual solvent in the first resin composition at the time of peeling is defined by the following formula. The same applies to the following.

[0157] Residual solvent amount (mass %) = (mass of the first resin composition before heating treatment - mass of the first resin composition after heating treatment) / mass of the first resin composition after heating treatment × 100

[0158] In addition, the heat treatment in measuring the residual solvent amount refers to a heat treatment at 140° C. for 15 minutes.

[0159] The amount of residual solvent during peeling can be adjusted by the drying temperature and drying time of the first resin composition on the support, the temperature of the support, and the like.

[0160] About 1C) process

[0161] The obtained film is then dried. Drying may be performed in one stage or in multiple stages. Alternatively, the film may be dried while being stretched as required.

[0162] Stretching can be performed according to the required optical properties, preferably in at least one direction, and can also be stretched in two orthogonal directions (for example, biaxial stretching in the width direction (TD direction) of the film and the conveying direction (MD direction) orthogonal thereto).

[0163] From the perspective of being used as a phase difference film for IPS, for example, the stretching ratio can be 1.01 to 2 times. The stretching ratio is defined as (the size of the film in the stretching direction after stretching) / (the size of the film in the stretching direction before stretching). It should be noted that in the case of biaxial stretching, it is preferred to set the above-mentioned stretching ratios for the TD direction and the MD direction respectively.

[0164] It should be noted that the in-plane slow axis direction of the film (the direction in which the in-plane refractive index is the largest) is usually the direction in which the stretching ratio is the largest.

[0165] When the glass transition temperature of the resin is set to Tg, the drying temperature (stretching temperature) during stretching is preferably (Tg-65)°C to (Tg+60)°C, and more preferably (Tg-50)°C to (Tg+50)°C. When the stretching temperature is above a certain temperature, the solvent is easily volatilized appropriately, so it is easy to adjust the stretching tension to an appropriate range. When it is below a certain temperature, the solvent does not volatilize excessively, so the stretchability is not easily impaired.

[0166] The stretching temperature (a) can be specified as the temperature inside the stretching machine or the atmosphere temperature such as the hot air temperature when drying is performed by a non-contact heating type such as a tenter machine, (b) can be specified as the temperature of the contact heating part or (c) can be specified as any one of the surface temperatures of the film (the surface to be dried) when drying is performed by a contact heating mold such as a hot roller.

[0167] The amount of residual solvent in the film at the start of stretching is preferably about the same as the amount of residual solvent in the film at the time of peeling, for example, preferably 20 to 30% by mass, more preferably 25 to 30% by mass.

[0168] The stretching of the film in the TD direction (width direction) can be performed by, for example, fixing both ends of the film with clamps or pins and enlarging the interval between the clamps or pins in the running direction (tenter method). The stretching of the film in the MD direction can be performed by, for example, giving a peripheral speed difference to a plurality of rolls and utilizing the peripheral speed difference between the rolls (roll method).

[0169] From the viewpoint of further reducing the amount of residual solvent, the film obtained after stretching is preferably further dried (post-dried). For example, the film obtained after stretching is preferably further dried while being conveyed with a roll or the like (under a state where a certain tension is applied).

[0170] The drying temperature (drying temperature in the case of not stretching or drying temperature after stretching) is preferably (Tg-30) to (Tg+30)°C, and more preferably (Tg-20) to (Tg)°C, when the glass transition temperature of the resin is set to Tg. When the drying temperature is above a certain temperature, it is easy to increase the volatilization rate of the solvent from the stretched film, so it is easy to improve the drying efficiency. When it is below a certain temperature, it is easy to suppress deformation caused by elongation of the film. The drying temperature can be determined in the same way as above.

[0171] 2) Regarding the process of forming the convex portion

[0172] Next, the second resin composition is cast on both ends in the width direction of the obtained film base 11 to form projections.

[0173] The second resin composition may be cast by melt casting or solution casting. In order to improve production efficiency, when the first resin composition is formed by solution casting in the step 1), the second resin composition is preferably also formed by solution casting.

[0174] That is, the projections 12 can be formed by applying the second resin composition (knurling solution) containing a resin and a solvent to both ends in the width direction of the film base 11 and then drying the composition.

[0175] (Second Resin Composition)

[0176] The resin contained in the second resin composition can be the same resin as the resin contained in the dope.

[0177] The solvent contained in the second resin composition at least includes an organic solvent (good solvent) that can dissolve the resin. In the example of a good solvent, a chlorine-based organic solvent such as dichloromethane or a non-chlorine-based organic solvent such as methyl acetate, ethyl acetate, acetone, tetrahydrofuran, cyclopentanone, toluene, etc. is included. Among them, from the viewpoint of easily dissolving cycloolefin resins, dichloromethane, cyclopentanone, toluene are preferred. Among them, from the viewpoint of high evaporation rate due to high saturated vapor pressure and easy adjustment of the S1 / S2 of the convex portion to the above range, ketones such as cyclopentanone or dichloromethane are more preferred.

[0178] The solvent contained in the second resin composition may further contain a poor solvent. As the poor solvent, the same poor solvent as that contained in the dope can be used.

[0179] From the viewpoint of adjusting the S1 / S2 of the convex portion to the above range, the viscosity of the second resin composition (knurling solution) during casting is preferably lower than the viscosity of the first resin composition (concentrated solution) during casting in the above step 1). Specifically, the ratio η2 / η1 of the viscosity η2 of the second resin composition during casting in the step 2) to the viscosity η1 of the first resin composition during casting in the step 1) is preferably 0.00003 to 0.01. When η2 / η1 is 0.00003 or more, the S1 / S2 of the convex portion 12 is likely to be 0.6 or more, and when it is 0.02 or less, the S1 / S2 of the convex portion 12 is likely to be 0.9 or less.

[0180] The viscosity η1 of the first resin composition during casting is preferably 10000 to 100000 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 (eg, viscometer RE-80L manufactured by Toki Sangyo Co., Ltd.).

[0181] The viscosity during casting can be adjusted, for example, by the resin concentration or the molecular weight of the resin in the solution casting method, and is preferably adjusted, for example, by the melting temperature or the molecular weight of the resin in the melt casting method.

[0182] 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, 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 less than 10% by mass, more preferably 3 to 7% by mass.

[0183] (Give)

[0184] The second resin composition can be applied by any method, for example, by casting using a die (preferably a reduced pressure die) or coating using a dispenser.

[0185] When a pressure reducing die is used, the gap of the slit is adjusted according to the thickness of the convex portion, and the width of the slit is adjusted according to the width of the convex portion. The gap of the slit is preferably 100 to 300 μm, and the width of the slit is preferably 3 to 20 mm. When a dispenser is used, the ejection amount is preferably 1 to 100 μg / 1 ejection, and the ejection interval is preferably 0.2 to 30 mm.

[0186] The temperature of the second resin composition during casting is, for example, 10 to 30° C., and preferably room temperature (23° C.).

[0187] (dry)

[0188] The second resin composition can be dried by any method, for example, by hot air drying or heating drying using electromagnetic waves (for example, heating drying using an infrared (IR) heater), etc. From the viewpoint of adjusting S1 / S2 of the protrusion 12 to the above range, a high drying speed is preferred, and heating drying using electromagnetic waves is more preferred.

[0189] From the viewpoint of adjusting S1 / S2 of the projections 12 to the above range, the second resin composition is preferably dried as soon as possible after being applied to the film base 11. Drying depends on the composition of the resin composition, but is preferably performed within 5 seconds after application.

[0190] The drying temperature is not particularly limited, but is preferably higher from the viewpoint of adjusting the S1 / S2 of the convex portion 12 to within the above range. Specifically, when the glass transition temperature of the resin contained in the second resin composition is Tg, the drying temperature is preferably 40 to (Tg-20)°C, and more preferably 80 to (Tg-10)°C. Specifically, it is preferably 40 to 120°C, and more preferably 80 to 100°C.

[0191] Then, the obtained film 10 is wound into a roll along the longitudinal direction.

[0192] 3) About the winding process

[0193] The obtained film base 11 is wound up in the longitudinal direction (direction perpendicular to the width direction) of the film 10 using a winder. Thus, a film wound up in a roll shape around a winding core, that is, a roll body of the film 10 can be obtained.

[0194] The winding method is not particularly limited, and may be a constant torque method, a constant tension method, a tapered tension method, or the like.

[0195] The winding tension when winding the film base 11 can be about 50 to 170 N. In this way, the longer the winding length is, the air accumulated between the films is released at once when winding into a roll, which is easy to cause winding deviation and adhesion. Even in such a case, by adjusting S1 / S2 of the convex portion 12 to the above range, it is possible to appropriately release excess air (and appropriately accumulate air between the films) while winding, which can suppress winding deviation and adhesion.

[0196] When the obtained film 10 is used, the portion where the convex portion 12 is formed 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 optical films include polarizer protective films (including phase difference films or brightness enhancement films, etc.), transparent substrate films, and light diffusion films. Among them, the film 10 is preferably used as a polarizer protective film.

[0197] 3. Film and method for manufacturing the same

[0198] As described above, the film of the present invention may be a film cut out from a roll of a strip-shaped film 10 and may have strip-shaped convex portions at both ends in the width direction.

[0199] Specifically, the film has a film base (corresponding to the film base 11) and strip-shaped convex portions provided at both ends of the film surface in the width direction (corresponding to the convex portions 12). In addition, in a cross section of the film perpendicular 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 more preferably satisfy 0.7≤S1 / S2≤0.9.

[0200] The shape of the convex portion in the cross section of the film perpendicular to the extending direction of the strip-shaped convex portion, the total area of ​​S1 and S2, the maximum height Tmax and the maximum width Wmax of the convex portion, and the ratio of the total area of ​​S1 and S2 to the area of ​​the film base are as described above. In addition, the shape of the film base 11 in the cross section of the film perpendicular to the extending direction of the strip-shaped convex portion (without a concave portion) and the thickness of the film base are also as described above.

[0201] This film can be produced in the same manner as the above roll production method except that, for example, the above winding step 3) is not included or the step of cutting the strip-shaped film rolled out from the roll is included after the above winding step 3).

[0202] [Modifications]

[0203] It should be noted that, in the above embodiment, the convex portions 12 are continuously arranged along the longitudinal direction of the film base 11 , but the present invention is not limited thereto. For example, the convex portions 12 may be intermittently arranged along the longitudinal direction of the film base 11 .

[0204] Figure 3A is a top view of a strip-shaped film according to another embodiment. Figure 3B yes Figure 3A 3B-3B line cross-sectional view. Figure 4A is a top view of a strip-shaped film according to another embodiment. Figure 4B yes Figure 4A 4B-4B line cross-sectional view.

[0205] That is, the convex portion 12 may be disposed intermittently along the length direction of the film base 11 (see Figure 3A The length of the projection 12 (the length in the longitudinal direction of the film base 11) may be about 0.04 to 10.0% relative to the width of the film base 11. The gap between the plurality of band-shaped projections 12 may be about 0.02 to 1.0% relative to the length of the projection 12.

[0206] Alternatively, the convex portion 12 may be arranged in an island shape along the length direction of the film base 11 (see Figure 4A ). Such a convex portion 12 can be formed by intermittently spraying by a dispenser. The spraying conditions can be as described above.

[0207] In addition, in the above embodiment, the shape of the convex portion 12 is shown as Figure 2 Examples of shapes shown (see Figure 2 ), but is not limited thereto.

[0208] Figure 5A to Figure 5C 1 is a diagram showing a modified example 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 a step shape (see Figure 5A ), or a trapezoid (see Figure 5B ). Alternatively, the height of the center portion of the convex portion 12 may be lower than the height of both ends of the convex portion 12 (see Figure 5C ).

[0209] In the above embodiment, an example is shown in which one convex portion 12 is arranged at each of the two end portions in the width direction of the film base 11 , but the present invention is not limited thereto, and a plurality of convex portions 12 may be arranged at each of the two end portions.

[0210] Furthermore, in the above-described embodiment, an example is shown in which the protrusions 12 are arranged only on one surface of the film base 11 , but the present invention is not limited thereto and the protrusions 12 may be arranged on both surfaces.

[0211] In addition, in the above-mentioned embodiment, an example is shown in which a knurling solution containing a resin and a solvent is applied and then dried to form the protrusion 12 (solution casting method), but it is not limited to this. The protrusion 12 can also be formed by applying a molten resin composition and then cooling and solidifying it (melt casting method).

[0212] That is, in the melt casting method, the roll can be obtained through the following steps: 1) a step of casting a molten first resin composition, cooling and solidifying it, to obtain a strip-shaped film base 11; 2) a step of applying a molten second resin composition to both ends in the width direction of the strip-shaped film base 11, cooling and solidifying it, to form a convex portion. In this case, the first resin composition and the second resin composition are respectively the same as the first resin composition and the second resin composition described above except that they do not contain a solvent.

[0213] Furthermore, it is preferred that the melt viscosity of the second resin composition during casting is lower than the melt viscosity of the first resin composition during film formation of the film base 11. The melt viscosity can be adjusted by the melting temperature or the weight average molecular weight of the resin, etc. 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 melting temperature of the second resin composition during casting can also be made higher than the melt viscosity of the first resin composition during film formation of the film base 11.

[0214] In addition, in the above embodiment, as a method for adjusting the shape of the protrusion 12, a method of adjusting the viscosity or resin concentration of the second resin composition, the imparting method, the drying conditions, etc. is shown, but it is not limited to this. For example, after casting the second resin composition, the two ends can be cut (cut) to adjust, or the film base 11 can be surface treated (hydrophilic treatment, etc.) to adjust.

[0215] Example

[0216] Hereinafter, the present invention will be specifically described with reference to Examples, but the present invention is not limited to these.

[0217] 1. Preparation of cycloolefin resin film (film base)

[0218] <Production of Cycloolefin Resin Film 1>

[0219] (Preparation of Microparticle Dispersion)

[0220] 10 parts by mass of R218 and 80 parts by mass of ethanol were stirred and mixed for 30 minutes using a dissolver, and then dispersed with mantongorin. 80 parts by mass of dichloromethane were added to the obtained solution while stirring, and stirred and mixed for 30 minutes using a dissolving stick, and then filtered with a filter (Advantech Toyo Co., Ltd.: polypropylene cartridge filter TCW-PPS-1N) to obtain a particle dispersion.

[0221] (Preparation of Dope)

[0222] Next, prepare a concentrated solution of the following composition. First, add dichloromethane to a pressure dissolving tank, and then add the following cycloolefin resin while stirring. Next, add the above-prepared fine particle dispersion, heat to 60°C, and stir to completely dissolve it. The heating temperature is increased from room temperature at 5°C / min, and after dissolving for 30 minutes, the temperature is lowered at 3°C / min. Use SHP150 manufactured by Roki Techno Co., Ltd. to filter it at a flow rate of 300L / m 2 h, filtration pressure 1.0×10 －6 Pa was filtered to obtain a concentrated solution.

[0223] G7810 manufactured by JSR Corporation (cycloolefin resin containing a structural unit represented by the following formula, weight average molecular weight 40,000, glass transition temperature 170° C.): 100 parts by mass

[0224] Dichloromethane: 150 parts by mass

[0225] Ethanol: 20 parts by mass

[0226] Microparticle dispersion: 150 parts by mass

[0227] [Chemistry 3]

[0228]

[0229] (Film Making)

[0230] The obtained dope was uniformly cast on a stainless steel belt support of an endless belt casting device at room temperature (23°C). The temperature of the stainless steel belt was 28°C and the conveying speed of the stainless steel belt was 20 m / min. Then, on the stainless steel belt support, the solvent was evaporated until the residual solvent content in the cast film was 25% by mass, and then the film was peeled off from the stainless steel belt support to obtain a film.

[0231] Next, the obtained film was stretched 1.2 times in the width direction under the condition of (Tg-15)° C. (Tg: Tg of the cycloolefin resin) using a tenter.

[0232] Next, while conveying the stretched film by roll, it is further dried at (Tg-10)°C until the residual solvent content measured by the above-mentioned headspace gas chromatography is in the range of 30 to 600 mass ppm, and then cut by a laser cutter and wound with the end clamped by the tenter clamp to obtain a cycloolefin resin film with a width of 1450 mm, a length of 4000 m, and a thickness of 20 μm.

[0233] <Production of Cycloolefin Resin Films 2 to 4>

[0234] Cycloolefin resin films 2 to 4 were obtained in the same manner as the cycloolefin resin film 1 except that the stretching ratio was changed so that the film thickness was 10 μm, 40 μm, and 60 μm.

[0235] 2. Preparation of solution for forming projections (second resin composition)

[0236] <Preparation of Solutions 1 to 3, 6 to 9, and 11 to 14>

[0237] The resins and solvents shown in Table 1 were mixed to give the resin concentrations shown in Table 1 to obtain projection-forming solutions 1 to 3, 6 to 9, and 11 to 14. Of these, solution 12 contained the same amount of silica particles (R218) as in the thin film.

[0238] <Preparation of Solution 4>

[0239] Polymethyl methacrylate (PMMA, weight average molecular weight 1,000,000) was dissolved in a solvent shown in Table 1 at 35° C. to obtain a convex-forming solution 4 .

[0240] <Preparation of Solutions 5 and 10>

[0241] Triacetyl cellulose (TAC, weight average molecular weight: 130,000) was dissolved in the solvent shown in Table 1 to obtain projection-forming solutions 5 and 10.

[0242] Table 1 shows the compositions and physical properties of the obtained convex-portion forming solutions 1 to 14.

[0243] [Table 1]

[0244]

[0245] 3. Making the roll

[0246] <Examples 1 to 6, 8, 10, 11, 16, Comparative Examples 1, 3, 5 and 6>

[0247] The solution shown in Table 2 was continuously applied to both ends of the cycloolefin resin film in the width direction at room temperature (23° C.) from a reduced pressure die (in the comparative example, a die) under the conditions of Table 2, and then dried to form Figure 1A as well as Figure 1B The convex part shown.

[0248] <Example 9>

[0249] The same method as in Example 1 was used to form a film except that the solution shown in Table 2 was applied intermittently under the conditions in Table 2. Figure 3A as well as Figure 3B The length of the convex portion (in the longitudinal direction of the cycloolefin resin film) was 100 mm, and the pitch between the convex portions was 10 mm.

[0250] <Examples 7 and 13 to 15>

[0251] The solution shown in Table 2 was applied by a dispenser to both ends of the cycloolefin resin film in the width direction under the conditions shown in the same table, and then dried to form a Figure 4A as well as Figure 4B In Example 12, the convex portions were formed on both sides of the film. The dispenser was SUPER HI JET manufactured by Musashi Engineering Co., Ltd.

[0252] <Example 12>

[0253] The convex portions were formed in the same manner as in Example 3 except that the coating shape of the convex portions was changed as shown in Table 2.

[0254] <Comparative Example 2>

[0255] The two ends of the single side of the cycloolefin resin film prepared as above in the width direction are embossed to form an embossed portion. The embossing is performed by pressurizing a metal ring having a heated concave-convex pattern (a shape of 9 concave-convex connected in the width direction). The processing pressure of the metal ring is 200 kPa and the temperature is 230°C. The embossed portion obtained has a thin-walled 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-walled portion (corresponding to the convex portion) is measured and the result is 0.48.

[0256] <Comparative Example 4>

[0257] The laser marking machine was used to irradiate the two ends of the width direction of one side of the cycloolefin resin film to form a laser irradiated portion. The laser irradiated portion had a thin-walled 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-walled portion (corresponding to the convex portion) was measured and the result was 0.47.

[0258] <Evaluation>

[0259] (Viscosity ratio)

[0260] The viscosity of the dope for film during casting and the viscosity of the solution for convex portion formation during casting in the rolls produced in Examples 1 to 16 and Comparative Examples 1 to 6 were measured using a viscometer RE-80L manufactured by Toki Sangyo Co., Ltd. The viscosity of the dope (first resin composition) during film formation (23° C.) was 27000 mPa·s, and the viscosity of the solution for convex portion formation (second resin composition) was a viscosity satisfying the viscosity ratio in Table 3.

[0261] In addition, the physical properties of the convex portions of the rolls obtained in Examples 1 to 16 and Comparative Examples 1 to 6, the shapes of the rolls, and the presence or absence of deformation of the films were evaluated by the following methods.

[0262] <Physical properties of convex portion>

[0263] The areas S1 and S2 of the convex portions in the cross section in the width direction of the film, the maximum height Tmax, and the maximum width Wmax of the convex portions were measured using a laser microscope. As the laser microscope, a laser microscope VK-X1000 manufactured by KEYENCE was used.

[0264] Specifically, the maximum height and maximum width of the projections were measured for an area of ​​100 mm in the longitudinal direction of the film and 15 mm in width centered on one row of projections, and their average values ​​were defined as "maximum height Tmax and maximum width Wmax of the projections".

[0265] Similarly, for an area of ​​100 mm in the longitudinal direction of the film and 15 mm in width centered on one row of convex portions, the area of ​​the lower half and the area of ​​the upper half of the area of ​​the convex portions, separated by a height of Tmax / 2, are measured using a laser microscope, and their average values ​​are set as "areas S1 and S2 of convex portion 12". It should be noted that, in the case of multiple rows of convex portions, the value of one row of convex portions is shown. In addition, in the case of dispenser coating or intermittent coating, the average value of the measured values ​​of the multiple convex portions present in the above-mentioned area is set.

[0266] (Shape of the roll)

[0267] The shape of the roll was measured by KEYENCE's XG-X2900 and CA-HL08MX (line scan camera) and CA-DZW50X (pattern lighting). Specifically, when observing the surface of the roll, the total area of ​​the deformation of 200μm×200μm or more was measured and judged by the area ratio (%) relative to the outermost surface of the roll (the area of ​​1 roll of the outermost film).

[0268] ◎: Less than 0.3%

[0269] ○: 0.3% or more but less than 0.5%

[0270] ○△: 0.5% or more but less than 1.0%

[0271] △: 1.0% or more but less than 2.0%

[0272] ×: 2.0% or more

[0273] If it is above ○△, it is judged as good

[0274] (Deformation of film)

[0275] Regarding the deformation of the film, the roll was pulled out and the number of deformation failures was counted and evaluated at a line speed of 5m / min using XG-X2900, CA-HL08MX (line scan camera) and CA-DZW50X (pattern lighting). The number of deformation failures was counted as 1 deformation of 100μm×100μm or more. Then, the deformation of the film was evaluated based on the following criteria.

[0276] ◎: Less than 10 / 1000m

[0277] ○: Less than 50 / 1000m

[0278] ○△: Less than 100 / 1000m

[0279] △: Less than 200 / 1000m

[0280] ×: 200 pieces / 1000m or more

[0281] If it is ○△ or more, it is judged as good.

[0282] Table 2 shows the production conditions of the rolls of Examples 1 to 16 and Comparative Examples 1 to 6, and Table 3 shows the evaluation results.

[0283] [Table 2]

[0284]

[0285] [Table 3]

[0286]

[0287] As shown in Table 3, it can be seen that the rolls of Examples 1 to 16 had little winding deviation and blocking, and little change in the shape of the rolls. In addition, it can be seen that the film also had little deformation.

[0288] In particular, it was found that by reducing the resin concentration of the convex portion forming solution, S1 / S2 can be appropriately reduced, and deformation of the roll and deformation of the film can be further reduced (comparison between Examples 3 and 9, and comparison between Examples 8 and 11).

[0289] In addition, it is known that by using ketones such as cyclopentanone as the solvent composition of the convex portion forming solution, S1 / S2 can be appropriately reduced, and deformation of the roll and film can be further reduced (compared with Examples 2, 3, and 10). This is believed to be because the saturated vapor pressure is high and the evaporation rate is high.

[0290] In addition, it can be seen that the deformation of the roll and the film can be further reduced by applying the convex portion forming solution using a dispenser compared to applying it using a reduced pressure die (comparison with Examples 1 and 14 to 15). This is believed to be because the curling of the film base caused by heat during drying can be reduced by applying the solution using a dispenser compared to applying it using a reduced pressure die.

[0291] In contrast, in Comparative Examples 1 and 3 where S1 / S2 exceeded 0.95, deformation of the roll or deformation of the film occurred. This is believed to be because the convex portion and the back surface of the film base were too close during winding, and the air could not be discharged, so the trapped air was released periodically, thereby periodically causing winding deviation or film adhesion.

[0292] In addition, it can be seen that the roll of Comparative Example 2 that was embossed or the roll of Comparative Example 4 that formed convex portions by laser irradiation both deformed the roll and deformed the film. This is believed to be because the area S2 was low, the embossed portion or the laser irradiated portion was crushed by stress, and the roll shape could not be maintained, resulting in blocking, etc.

[0293] <Examples 17 to 21>

[0294] The roll was formed in the same manner as in Example 3 except that the gap between the slits was changed as shown in Table 4.

[0295] <Examples 22 to 24>

[0296] A roll was formed in the same manner as in Example 7 except that the number of columns (number of rows) of convex portions and the pitch between convex portions (in the longitudinal direction of the film) were changed as shown in Table 4.

[0297] <Examples 25 to 27>

[0298] A roll 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.

[0299] <Examples 28 to 30>

[0300] A roll was formed in the same manner as in Example 3 except that the thickness of the film was changed as shown in Table 4.

[0301] <Example 31>

[0302] Except having changed the discharge width as shown in Table 4, the roll body was formed in the same manner as in Example 3.

[0303] <Examples 32 and 33>

[0304] A roll was formed in the same manner as in Example 7 except that the discharge amount and the pitch between convex portions (in the longitudinal direction of the film) were changed as shown in Table 4.

[0305] Then, the shapes of the rolls and the deformation of the films of Examples 17 to 33 were evaluated in the same manner as above.

[0306] Table 4 shows the production conditions of the rolls of Examples 17 to 33, and Table 5 shows the evaluation results.

[0307] [Table 4]

[0308]

[0309] [Table 5]

[0310]

[0311] As shown in Table 5, it can be seen that the rolls of Examples 17 to 33 had little winding deviation or blocking, and little change in the shape of the roll.

[0312] Industrial Applicability

[0313] According to the present invention, a film roll and a method for manufacturing the same can be provided, wherein the film roll is not easily crushed by winding pressure and can suppress winding deviation or sticking when an external impact is applied by maintaining an appropriate amount of air between the films.

[0314] Description of Reference Numerals

[0315] 10 Strip-shaped film

[0316] 11. Film base

[0317] 12 convex part

Claims

1. A film having strip-shaped convex portions at both ends in the width direction, characterized in that: When the maximum height of the convex portion is set to Tmax, the area of ​​the convex region located above the convex midpoint (Tmax / 2) relative to the maximum height Tmax of the convex portion is set to S1, and the area of ​​the convex region located below the midpoint is set to S2, S1 and S2 satisfy the following formula (1): Formula (1): 0.6≤S1 / S2≤0.

95.

2. The film according to claim 1, characterized in that The height of the center portion of the convex portion is higher than the height of both end portions of the convex portion, or is the same as the height of both end portions of the convex portion.

3. The film according to claim 1 or 2, characterized in that In a cross section of the film perpendicular to the extending direction of the band-shaped protrusions, The shape of the protrusion is arcuate or trapezoidal.

4. The film according to any one of claims 1 to 3, characterized in that Tmax is 0.3~4.0μm.

5. The film according to any one of claims 1 to 4, characterized in that The film comprises a film base and the strip-shaped protrusions arranged at both ends in the width direction of the surface of the film base. The film base has no recessed portion.

6. The film according to claim 5, characterized in that The thickness of the film base is 3-40 μm.

7. The film according to claim 5 or 6, characterized in that The film base is a resin film.

8. The film according to claim 7, characterized in that The film base is an optical film.

9. A method for producing a film, wherein the film is the film according to any one of claims 1 to 8 and has belt-shaped convex portions at both ends in the width direction, characterized in that: Including the following processes: 1) a step of casting a first resin composition to obtain a strip-shaped film base; 2) a step of casting a second resin composition on both ends in the width direction of the surface of the strip-shaped film base to form the strip-shaped convex portion; The ratio η2 / η1 of the viscosity η2 of the second resin composition during casting in the step 2) to the viscosity η1 of the first resin composition during casting in the step 1) is 0.00003 to 0.

02.

10. The method for producing a thin film according to claim 9, wherein: The first resin composition and the second resin composition each contain a resin and a solvent, The second resin composition has a lower resin concentration than the first resin composition.

11. The method for producing a thin film according to claim 10, wherein: The resin concentration of the second resin composition exceeds 2 mass % and is 10 mass % or less.

12. The method for producing a thin film according to any one of claims 9 to 11, characterized in that: The thickness of the film base is 3-40 μm.

13. The method for producing a thin film according to any one of claims 9 to 12, characterized in that: The film base is an optical film.

14. A roll body comprising a strip-shaped film having strip-shaped convex portions at both ends in the width direction, characterized in that: When the maximum height of the convex portion is set to Tmax, the area of ​​the convex region located above the convex midpoint (Tmax / 2) relative to the maximum height Tmax of the convex portion is set to S1, and the area of ​​the convex region located below the midpoint is set to S2, S1 and S2 satisfy the following formula (1): Formula (1): 0.6≤S1 / S2≤0.

95.

15. A method for producing a roll, wherein the roll is the roll according to claim 14, wherein a strip-shaped film having strip-shaped convex portions at both ends in the width direction is wound, wherein: Including the following processes: 1) a step of casting a first resin composition to obtain a strip-shaped film base; 2) a step of casting a second resin composition on both ends in the width direction of the surface of the strip-shaped film base to form the strip-shaped convex portion; The ratio η2 / η1 of the viscosity η2 of the second resin composition during casting in the step 2) to the viscosity η1 of the first resin composition during casting in the step 1) is 0.00003 to 0.02.

Images