Film and film rolls, method for manufacturing film

Abstract

The film of the present invention has a film base and protruding parts disposed on both ends of the surface of the film base. The film base and the protruding parts include the same type of thermoplastic resin, and the height of the protruding parts is 0.5-3 μm. The haze ratio Hz2 / Hz1 is 1.1-4.5 when the haze value of the region where the protruding parts are not disposed is defined as Hz1, and the haze value of the regions where the protruding parts are disposed is defined as Hz2.

Description

[Technical Field]

[0001] This invention relates to a film, a film roll, and a method for manufacturing a film. [Background technology]

[0002] Resin films, primarily composed of cycloolefin resins and (meth)acrylic resins, possess excellent transparency and dimensional stability, and are therefore used as optical films, such as protective films for polarizing plates. Optical films are typically stored or transported in roll form for ease of handling and manufacturing efficiency.

[0003] When storing or transporting films in this rolled state, knurling (a textured surface) may be formed on both ends of the film in the width direction to prevent quality defects caused by the films sticking together. Methods for forming the knurling include heating and pressing with an embossing roller or laser irradiation.

[0004] However, the protrusions formed by these methods are prone to crushing or chipping. As a result, not only is it difficult to prevent the films from sticking together, but the chipped parts can become foreign objects and scratch the surface of the film.

[0005] In contrast, a method is known in which knurled portions are formed on both ends in the width direction of a film by a coating method (see, for example, Patent Documents 1 to 3). For example, optical laminates having a base film, an optical functional layer such as a hard coat layer, and knurled portions arranged on both ends in the width direction of its surface are known (for example, Patent Document 2), and film materials having a base, a coating such as a hard coat layer, and thickened portions arranged on both ends in the width direction of its surface are known (for example, Patent Document 3). The base film or base (film base) is an acrylic resin film or a cellulose triacetate film; the knurled portions or thickened portions (protrusions) are cured products of a resin composition containing an ultraviolet-curable resin, similar to the optical functional layer such as a hard coat layer or the coating. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2012-206312 [Patent Document 2] Japanese Patent Publication No. 2017-109350 [Patent Document 3] Japanese Patent Publication No. 2014-159137 [Overview of the project] [Problems that the invention aims to solve]

[0007] As shown in Patent Documents 2 and 3, the protrusions made of cured ultraviolet-curable resin compositions are less likely to be crushed when the film is wound into a roll. However, because the protrusions are not only too hard but also have residual shrinkage stress from curing, they have poor adhesion to the film base and are prone to peeling. As a result, the knurling function is easily impaired, which can lead to blocking and a deterioration in the winding shape of the film roll.

[0008] Blocking and deterioration of the film roll's winding shape can easily increase variations in optical properties, for example, in optical films; and variations in optical properties can easily cause light leakage when displaying black in display devices. In particular, optical films used in high-resolution display devices such as 8K require even less variation in optical properties than before, so it is desirable to further suppress the blocking and deterioration of the film roll's winding shape as described above.

[0009] The present invention has been made in view of the above circumstances, and aims to provide a film and film roll that can suppress blocking and deterioration of winding shape during storage of films such as optical films, and reduce variations in optical properties. [Means for solving the problem]

[0010] The above problem can be solved by the following configuration.

[0011] The film of the present invention is a film including a film base and convex portions disposed at both end portions on the surface of the film base, wherein the film base and the convex portions contain the same type of thermoplastic resin, the height of the convex portions is 0.5 to 3 μm, and when the haze value of the region where the convex portions are not disposed on the film is Hz1 and the haze value of the region where the convex portions are disposed is Hz2, the haze ratio Hz2 / Hz1 is 1.1 to 4.5.

[0012] The film roll of the present invention includes the film of the present invention.

[0013] The method for manufacturing the film of the present invention includes: 1) a step of casting a first resin composition to obtain a strip-shaped film base; and 2) a step of applying a second resin composition to both end portions in the width direction on the surface of the strip-shaped film base to form convex portions.

Effects of the Invention

[0014] According to the present invention, it is possible to provide a film and a film roll that can suppress blocking and deterioration of the winding shape during storage of a film such as an optical film, and reduce variations in optical characteristics.

Brief Description of the Drawings

[0015] [Figure 1] FIG. 1A is a plan view of the film according to the present embodiment, and FIG. 1B is a cross-sectional view taken along line 1B-1B of FIG. 1A. [Figure 2] FIG. 2A is a partially enlarged plan view of the dotted portion 2A in FIG. 1A, and FIG. 2B is a partially enlarged cross-sectional view of the convex portion in FIG. 1B. [Figure 3] FIG. 3A is a plan view of a film according to a modified example, and FIG. 3B is a cross-sectional view taken along line 3B-3B of FIG. 3A. [Figure 4] FIG. 4 is a partially enlarged plan view of a film according to a comparative example.

Embodiments for Carrying Out the Invention

[0016] The inventors have found that by 1) using the same type of thermoplastic resin in the film base and the protrusions, the adhesion of the protrusions (to the film base) is improved, and by 2) reducing the height of the protrusions and setting the ratio of the haze value Hz1 in the area where the protrusions are not located to the haze value Hz2 in the area where the protrusions are located (Hz2 / Hz1) within a predetermined range, the protrusions are less likely to be crushed, and deformation when the film is wound into a roll can be reduced.

[0017] The reason for this is not clear, but it can be inferred as follows: As described in 1) above, the protrusions containing thermoplastic resin do not become too hard, and if the thermoplastic resin contained in the film base and the protrusions is of the same type, the affinity between the two is high, making it easy for them to adhere firmly. Furthermore, as described in 2) above, by appropriately lowering the height of the protrusions, for example, when a constant radial pressure (force acting in the direction that crushes the protrusions) is applied while the film is wound, the lower the height of the protrusions, the less the absolute amount of crushing the protrusions will be (assuming the degree of crushing of the protrusions is constant). In addition, variations in the height of the protrusions due to crushing can also be reduced. Moreover, by adjusting the height of the protrusions and the density of the protrusions, the haze ratio Hz2 / Hz1 can be set within a predetermined range, which not only reduces the amount of crushing of the protrusions but also makes the protrusions less susceptible to crushing. This suppresses roll deformation caused by the crushing of the protrusions.

[0018] Furthermore, since the protrusions are formed by applying a resin composition to the film body (film base), unlike conventional embossing or laser irradiation methods, the resulting film base is less prone to the formation of thin or brittle areas due to thermal degradation. Therefore, even when winding pressure is applied to the protrusions, chipping does not occur starting from thin or brittle areas due to thermal degradation, thus suppressing the generation of foreign matter. This also suppresses scratches on the film surface, further reducing the deterioration of the optical properties of the resulting film.

[0019] The film of the present invention may be in the form of a strip or a sheet (obtained by cutting a strip of film to a predetermined length). Furthermore, the strip of film may be wound into a roll to form a film roll. The following embodiments will be described using an example of a strip of film.

[0020] 1. Film Figure 1A is a plan view of the strip-shaped film according to this embodiment, and Figure 1B is a cross-sectional view taken along line 1B-1B in Figure 1A. Figure 2A is a partially enlarged plan view of the dotted line portion 2A in Figure 1A, and Figure 2B is a partially enlarged cross-sectional view of the convex portion in Figure 1B. Note that in Figure 1B, the hatching of the cross-section has been omitted for clarity.

[0021] As shown in Figures 1A and 1B, the strip-shaped film 10 according to this embodiment includes a film base 11 and protrusions 12 arranged (formed by coating) at both ends in the width direction on its surface.

[0022] 1-1. Film base 11 The film base 11 may be a resin film, preferably a resin film usable as an optical film. The resin film comprises a first resin composition containing a thermoplastic resin.

[0023] (thermoplastic resin) The thermoplastic resin contained in the resin film is not particularly limited as long as it is suitable for optical films, but examples include cycloolefin resins, (meth)acrylic resins, polyimides, cellulose esters, polyesters, and polycarbonates. Among these, 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).

[0024] (Cycloolefin resin) Cycloolefin resins are polymers that contain structural units derived from norbornene monomers. Norbornene monomers are represented by the following formula (1). [ka]

[0025] R in equation (1) 1 ~R 4 These represent a hydrogen atom, a halogen atom, a hydrocarbon group, or a polar group, respectively.

[0026] Examples of halogen atoms include fluorine atoms and chlorine atoms.

[0027] The hydrocarbon group is a hydrocarbon group having 1 to 10 carbon atoms, preferably 1 to 4, more preferably 1 or 2 carbon atoms. Examples of hydrocarbon groups include alkyl groups such as methyl, ethyl, propyl, and butyl groups. The hydrocarbon group may further have a divalent linking group containing an oxygen atom, nitrogen atom, sulfur atom, or silicon atom (e.g., carbonyl group, imino group, ether bond, silyl ether bond, thioether bond, etc.).

[0028] Examples of polar groups include linking groups such as carboxyl groups, hydroxyl groups, alkoxy groups, alkoxycarbonyl groups, allyloxycarbonyl groups, amino groups, amide groups, and methylene groups (-(CH2) n This includes groups to which these groups are bonded via (where n is an integer of 1 or more). Among these, alkoxycarbonyl groups and aryloxycarbonyl groups are preferred, and alkoxycarbonyl groups are more preferred.

[0029] Among them, R 1 ~R 4At least one of them is preferably a polar group. A cycloolefin resin containing a structural unit derived from a norbornene monomer having a polar group is, for example, easily dissolved in a solvent when forming a film by a solution casting method, and easily raises the glass transition temperature of the obtained film. On the other hand, in the melt film forming method, it may be a cycloolefin resin that does not contain a structural unit derived from a norbornene monomer having a polar group.

[0030] Also, R 1 ~R 4 Of these, R 1 and R 2 Both (or R 3 and R 4 Both) may be hydrogen atoms.

[0031] In formula (1), p represents an integer from 0 to 2. From the viewpoint of enhancing the heat resistance of the optical film, p is preferably 1 to 2.

[0032] Among the norbornene monomers represented by formula (1), examples of the norbornene monomers having a polar group include the following.

[0033]

Chemical formula

[0034] Examples of the norbornene monomers having no polar group include the following.

Chemical formula

[0035] The content of the structural unit derived from the norbornene monomer can be 50 to 100 mol% with respect to all the structural units constituting the cycloolefin resin.

[0036] Cycloolefin resins may further contain structural units derived from norbornene monomers and structural units derived from other copolymerizable monomers. Examples of other copolymerizable monomers include norbornene monomers without polar groups (if the norbornene monomer has polar groups) and cycloolefin monomers without a norbornene skeleton, such as cyclobutene, cyclopentene, cycloheptene, and dicyclopentadiene.

[0037] The weight-average molecular weight Mw of the cycloolefin resin is not particularly limited, but is preferably between 20,000 and 300,000, more preferably between 30,000 and 250,000, and even more preferably between 40,000 and 200,000. When the Mw of the cycloolefin resin is within the above range, the mechanical properties of the film can be improved without impairing moldability.

[0038] The Mw of cycloolefin resins can be measured in polystyrene equivalent by gel permeation chromatography (GPC). Specifically, it can be measured using a Tosoh HLC8220GPC and columns (Tosoh TSK-GEL G6000HXL-G5000HXL-G5000HXL-G4000HXL-G3000HXL in series).

[0039] The glass transition temperature (Tg) of cycloolefin resins is usually preferably 110°C or higher, more preferably 110 to 350°C, and even more preferably 120 to 250°C. A Tg of 110°C or higher makes it easier to obtain sufficient heat resistance, while a Tg of 350°C or lower can suppress thermal degradation of the cycloolefin resin during molding.

[0040] Tg can be measured using DSC (Differential Scanning Colorimetry) in accordance with JIS K 7121-2012 or ASTM D 3418-82.

[0041] ((meth)acrylic resin) The (meth)acrylic resin is preferably a polymer containing structural units derived from methyl methacrylate. The polymer may further contain structural units derived from monomers copolymerizable with methyl methacrylate.

[0042] Other monomers copolymerizable with methyl methacrylate include alkyl(meth)acrylates with 1 to 18 carbon atoms other than methyl methacrylate, such as 2-ethylhexyl methacrylate; α,β-unsaturated acids such as (meth)acrylic acid; unsaturated dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid; styrenes such as styrene and α-methylstyrene; maleic anhydride; maleimides such as maleimide and N-phenylmaleimide; and glutaric anhydride.

[0043] The content of structural units derived from methyl methacrylate is preferably 50% by mass or more, and more preferably 70% by mass or more, relative to the total structural units constituting the polymer.

[0044] The Mw of the (meth)acrylic resin is preferably between 400,000 and 3,000,000, and more preferably between 500,000 and 2,000,000. When the Mw of the (meth)acrylic resin is within the above range, sufficient mechanical strength can be imparted to the film. The Mw of the (meth)acrylic resin can be measured by the same method as described above.

[0045] The Tg of the (meth)acrylic resin is preferably 90°C or higher, and more preferably 100 to 150°C. Having the Tg of the (meth)acrylic resin within this range makes it easier to improve the heat resistance of the optical film. The Tg of the (meth)acrylic resin can be measured by the same method as described above.

[0046] The content of cycloolefin resin or (meth)acrylic resin is preferably 50% by mass or more, and more preferably 70% by mass or more, relative to the optical film.

[0047] (Other ingredients) The optical film may contain other components as needed. Examples of other components include rubber particles, matting agents, and antioxidants.

[0048] Rubber particles can impart flexibility to the film. The rubber particles are graft copolymers containing rubbery polymers (crosslinked polymers). Examples of rubbery polymers include butadiene-based crosslinked polymers, (meth)acrylic-based crosslinked polymers, and organosiloxane-based crosslinked polymers. Among these, (meth)acrylic-based crosslinked polymers are preferred, and acrylic-based crosslinked polymers (acrylic rubbery polymers) are more preferred, from the viewpoint of having a small refractive index difference with methacrylic resins and not impairing the transparency of the optical film.

[0049] A matting agent can create irregularities on the surface of an optical film, thereby imparting slipperiness. The matting agent may be inorganic particles or resin particles. Examples of inorganic particles include fine particles of silicon dioxide, titanium dioxide, aluminum oxide, zirconium oxide, and calcium carbonate, with silicon dioxide particles being preferred.

[0050] The antioxidant is not particularly limited, but for example, hindered phenol antioxidants can be used.

[0051] [Physical properties] Since the film base 11 is not embossed or laser-irradiated, it does not have thin sections formed by heating and pressing with an embossing roller or melting with laser irradiation. In other words, the thickness of the film base 11 is constant. The thickness of the film base 11 is not particularly limited, but is preferably 5 to 40 μm, more preferably 10 to 40 μm, and even more preferably 15 to 40 μm.

[0052] The length (winding length) of the film base 11 is not particularly limited, but is preferably 2000 to 15000 m, and more preferably 3000 to 12000 m. The width of the film base 11 is not particularly limited, but is preferably 950 to 3000 mm.

[0053] (Phase difference Ro and Rt) The film base 11 may have phase differences Ro and Rt depending on its application. For example, the in-plane phase difference Ro of the film base 11, measured at a measurement wavelength of 590 nm and under conditions of 23°C and 55% RH, preferably satisfies 40 nm ≤ Ro ≤ 60 nm, and the phase difference Rt in the thickness direction preferably satisfies 115 nm ≤ Rt ≤ 145 nm. Such a film base 11 is suitable as a phase difference film to be combined with, for example, a VA-type liquid crystal cell. Furthermore, if 0 nm ≤ Ro ≤ 10 nm and -20 nm ≤ Rt ≤ 20 nm, it is suitable as a phase difference film to be combined with an IPS-type liquid crystal cell.

[0054] Ro and Rt are defined by the following formulas, respectively. Equation (1): Ro = (nx - ny) × d Equation (2): Rt = ((nx + ny) / 2 - nz) × d (In the formula, nx represents the refractive index of the film base 11 in the in-plane slow axis direction (the direction in which the refractive index is maximum). ny represents the refractive index in the direction perpendicular to the in-plane slow axis of the film base 11. nz represents the refractive index in the thickness direction of the film base 11. d represents the thickness (nm) of the film base 11.

[0055] The in-plane lagging axis of the film base 11 can be confirmed using an automated birefringent AxoScan Mueller Matrix Polarimeter (manufactured by Axometrics).

[0056] Ro and Rt can be measured by the following methods. 1) The film base 11 is conditioned for 24 hours in an environment of 23°C and 55% RH. The average refractive index of this film base 11 is measured using an Abbe refractometer, and the thickness d is measured using a commercially available micrometer. 2) The phase difference Ro and Rt of the film base 11 after humidity control are measured at a measurement wavelength of 550 nm using an automated birefringent AxoScan Mueller Matrix Polarimeter (manufactured by Axometrics) in an environment of 23°C and 55% RH.

[0057] 1-2. Convex part 12 The protrusions 12 are a resin composition applied to both ends in the width direction of the surface of the film base 11. Specifically, the protrusions 12 are arranged discontinuously or continuously along the longitudinal direction of the film base 11 at both ends in the width direction of the surface of the film base 11. In this embodiment, a plurality of protrusions 12 are arranged discontinuously (in an island-like manner) (see Figure 2A). The protrusions 12 may be integrated with the film base 11 or they may be separate.

[0058] In a cross-section passing through the apex (highest point) of the protrusion 12 along the width direction of the film 10, the height t of the protrusion 12 is 0.5 to 3 μm (see Figure 2B). If the height t of the protrusion 12 is 0.5 μm or more, it is possible to sufficiently suppress the adhesion between the film bases 11 when the film 10 is wound into a roll. If the height t of the protrusion 12 is 3 μm or less, the absolute amount of deformation of the protrusion 12 when the film 10 is wound into a roll is small, making it possible to make the film roll less prone to deformation. From a similar viewpoint, it is preferable that the height t of the protrusion 12 is 1.0 to 2.0 μm. Note that the height t of the protrusion 12 is the height from the surface of the film base 11 to the apex of the protrusion 12.

[0059] The height t of the protrusion 12 is preferably 1 to 30% of the thickness of the film base 11, and more preferably 2 to 10%.

[0060] In a cross-section of the film 10 along the width direction, passing through the apex of the protrusion 12, the width w of the protrusion 12 is not particularly limited, but is preferably 500 to 2000 μm. If the width w of the protrusion 12 is 500 μm or more, the support area can be increased, making the protrusion 12 less likely to collapse. If it is 2000 μm or less, drying proceeds easily when forming the protrusion by solution coating, and cooling proceeds easily when forming by melt, making it easier to efficiently produce the film of the present invention. From a similar viewpoint, the width w of the protrusion 12 is more preferably 700 to 1500 μm. The width w of the protrusion 12 is the maximum width of the protrusion 12 in the above cross-section.

[0061] The height t and width w of the protrusion 12 can be measured using a laser microscope. For example, a Keyence VK-X1000 laser microscope can be used. The measurement is performed in the region where the protrusion 12 is located, measuring the height t and width w of the protrusion over a range of 100 mm in the length direction (Y direction in Figure 2A) and 15 mm in the width direction (X direction in Figure 2A) of the film 10, and the average value of these measurements is defined as the "height t and width w of the protrusion".

[0062] When the haze value of region a1 of the film 10 where no protrusions 12 are located is Hz1, and the haze value of region a2 where the protrusions 12 are located is Hz2 (see Figure 1A), the haze ratio Hz2 / Hz1 is 1.1 to 4.5. By setting Hz2 / Hz1 to 1.1 or higher (for example, by setting the height of the protrusions 12 or the density of the protrusions 12 above a certain level), the protrusions 12 can function as knurling areas while being less prone to collapse. Furthermore, by setting Hz2 / Hz1 to 4.5 or lower (for example, by setting the height of the protrusions 12 below a certain level), the absolute amount of collapse of the protrusions can be further reduced. From a similar viewpoint, it is preferable that Hz2 / Hz1 be between 1.5 and 3.0.

[0063] The haze ratio Hz2 / Hz1 of the film base 11 can be calculated by taking 10 measurements at 10 mm intervals along the longitudinal direction of the optical film using a haze meter (NDH2000, manufactured by Nippon Denshoku Industries Co., Ltd.) in an environment of 23℃ and 50%RH, for both the region a2 where the protrusions 12 are located and the region a1 where the protrusions 12 are not located (measurement area Φ11m, area 95mm2) of the film base 11, and determining the average value of these measurements, then calculating the ratio from these values.

[0064] The Hz2 / Hz1 of the film base 11 can be adjusted by the height, width, density, and composition of the protrusions 12. For example, the higher the height t of the protrusions 12, the wider the width of the protrusions 12, and the higher the density of the protrusions 12, the larger the Hz2 / Hz1 of the film base 11 tends to be. Conversely, if the height t of the protrusions 12 is low and the thermoplastic resin constituting the protrusions 12 and the thermoplastic resin constituting the film base 11 are of the same type, the Hz2 / Hz1 of the film base 11 tends to be small.

[0065] In a cross-section along the width direction of the film 10, passing through the vertices of the protrusions 12, the shape of the protrusions 12 is not particularly limited and may be a rectangle, a triangle, or a circular segment. A circular segment is a shape formed by connecting both ends of a circular or elliptical arc with a straight line, and examples include a semicircle and a semiellipse. In this embodiment, the shape of the protrusions 12 in the above cross-section is circular.

[0066] The distance p between the centers of the multiple protrusions 12 is not particularly limited, but can be, for example, 0.5 to 10 mm, preferably 1 to 5 mm (see Figure 2A). If the distance p between the centers of the multiple protrusions 12 is 0.5 mm or more, it is easier to appropriately adjust the amount of air contained between the films when winding them into a roll, and if it is 10 mm or less, the density of the protrusions 12 can be moderately increased, making the protrusions 12 less likely to be crushed. Note that the distance p between centers refers to the minimum distance between the centers (centroids) of adjacent multiple protrusions 12 when the film 10 is viewed from above.

[0067] The density of the protrusions 12 depends on factors such as the width of the protrusions 12, but for example, it is 2 to 160 per cm. 2 Preferably, the density is 10-60 pieces / cm 2 It is more preferable that the density of the protrusions 12 is within the above range.

[0068] The protrusion 12 contains a second resin composition which includes a thermoplastic resin.

[0069] The thermoplastic resin contained in the protrusions 12 is of the same type as the thermoplastic resin contained in the film base 11. For example, if the thermoplastic resin contained in the film base 11 is a cycloolefin resin, it is preferable that the resin contained in the protrusions 12 is also a cycloolefin resin. If the thermoplastic resin contained in the film base 11 and the thermoplastic resin contained in the protrusions 12 are of the same type, the adhesion between the protrusions 12 and the film base 11 can be improved.

[0070] "The same type of thermoplastic resin" refers to thermoplastic resins that have the same main component monomer (the most abundant component), but the type and content of copolymer component monomers, as well as physical properties such as the weight-average molecular weight (Mw) and glass transition temperature (Tg) of the resin, may differ.

[0071] The resin content is not particularly limited, but it is preferably 60% by mass or more, and more preferably 70-100% by mass, relative to the second resin composition constituting the protrusion 12.

[0072] The protrusions 12 may further contain components similar to those in the film base 11 (e.g., fine particles) as needed. However, from the viewpoint of preventing slippage between the protrusions 12 and the back surface of the film base 11 when the film 10 is wound up, and facilitating appropriate adhesion, it is preferable that the content of fine particles in the protrusions 12 is less than the content of fine particles in the film base 11, and more preferably that they contain no fine particles at all.

[0073] 2. Film manufacturing method The film of the present invention can be obtained by 1) casting a first resin composition onto a support to obtain a strip-shaped film base 11, and 2) applying a second resin composition to both ends in the width direction of the surface of the strip-shaped film base 11 to form protrusions.

[0074] 1) Regarding the process of obtaining the film base 11 The first resin composition is cast to obtain a strip-shaped film base 11.

[0075] The first resin composition may be cast by a melt casting method or a solution casting method. In particular, from the viewpoint of being able to use high molecular weight resins, the casting of the first resin composition is preferably carried out by a solution casting method.

[0076] In other words, the film base 11 can be obtained through the steps of: obtaining a dope (first resin composition) (preparation of dope); casting the obtained dope onto a support, drying and peeling it off to obtain a film-like material (casting); and drying and stretching the obtained film-like material (drying and stretching).

[0077] (Preparation of dope) The resin is dissolved in a solvent to prepare the first resin composition.

[0078] The solvent used must include at least an organic solvent (good solvent) capable of dissolving the resin. Examples of good solvents include chlorinated organic solvents such as dichloromethane, and non-chlorinated organic solvents such as methyl acetate, ethyl acetate, acetone, and tetrahydrofuran. Among these, methylene chloride is preferred.

[0079] The solvent used may further contain a poor solvent. Examples of poor solvents include linear or branched aliphatic alcohols having 1 to 4 carbon atoms. When the proportion of alcohol in the dope increases, the film-like material is more likely to gel, and peeling from the metal support is easier. Examples of linear or branched aliphatic alcohols having 1 to 4 carbon atoms include methanol, ethanol, n-propanol, iso-propanol, n-butanol, sec-butanol, and tert-butanol. Among these, methanol and ethanol are preferred from the viewpoint of stability and drying properties.

[0080] (Ryuen) Next, the obtained first resin composition is cast onto a support. The casting of the first resin composition can be carried out by extrusion from a casting die. The temperature of the first resin composition during casting is usually 15 to 30°C, preferably room temperature (23°C).

[0081] Next, the solvent in the first resin composition cast onto the support is appropriately evaporated (dried), and then peeled off from the support to obtain a film-like material.

[0082] The amount of residual solvent in the first resin composition at the time of peeling is preferably 25% by mass or more, more preferably 30-37% by mass, and even more preferably 30-35% by mass. When the amount of residual solvent at the time of peeling is 25% by mass or more, the solvent is easily evaporated rapidly from the film-like material after peeling. Also, when the amount of residual solvent at the time of peeling is 37% by mass or less, excessive stretching of the film-like material due to peeling can be suppressed.

[0083] The amount of residual solvent in the first resin composition at the time of peeling is defined by the following formula. The same applies below. Residual solvent amount (mass%) = (Mass of the first resin composition before heat treatment - Mass of the first resin composition after heat treatment) / Mass of the first resin composition after heat treatment × 100 Note that the heat treatment used when measuring the amount of residual solvent refers to a heat treatment at 140°C for 15 minutes.

[0084] (drying / stretching) Then, the resulting film-like material is dried. Drying may be carried out in one step or in multiple steps. Furthermore, drying may be carried out while stretching the material as needed.

[0085] The stretching may be carried out according to the required optical properties, and it is preferable to stretch in at least one direction, but it may also be stretched in two mutually orthogonal directions (for example, biaxial stretching in the width direction of the film (TD direction) and the transport direction (MD direction) perpendicular to it).

[0086] The stretching ratio can be 1.01 to 2 times, for example, when used as a phase difference film. The stretching ratio is defined as (stretched size of the film after stretching) / (stretched size of the film before stretching). When biaxial stretching is performed, it is preferable to use the above stretching ratio for both the TD direction and the MD direction. The in-plane slow axis direction of the film (the direction in which the refractive index is maximum in the plane) is usually the direction in which the stretching ratio is maximum.

[0087] The drying temperature during stretching (stretching temperature) is preferably (Tg-65)°C to (Tg+60)°C, and more preferably (Tg-50)°C to (Tg+50)°C, where Tg is the glass transition temperature of the resin. If the stretching temperature is above a certain level, the solvent is easily evaporated to an appropriate degree, making it easier to adjust the stretching tension to an appropriate range. If the stretching temperature is below a certain level, the solvent does not evaporate excessively, so the stretchability is less likely to be impaired.

[0088] 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, and more preferably 25 to 30% by mass.

[0089] Stretching of a film-like material in the TD direction (width direction) can be done, for example, by fixing both ends of the film-like material with clips or pins and widening the distance between the clips or pins in the direction of travel (tenter method). Stretching of a film-like material in the MD direction can be done, for example, by creating a difference in peripheral speed between multiple rolls and utilizing the difference in peripheral speed between them (roll method).

[0090] From the viewpoint of further reducing the amount of residual solvent, it is preferable to further dry (post-dry) the film obtained after stretching. For example, it is preferable to further dry the film obtained after stretching while conveying it with rolls or the like (while applying a certain tension).

[0091] The drying temperature is preferably (Tg-30) to (Tg+30)°C, and more preferably (Tg-20) to Tg°C, where Tg is the glass transition temperature of the resin. If the drying temperature is above a certain level, the rate of solvent evaporation from the stretched film is increased, thus improving drying efficiency. If the drying temperature is below a certain level, deformation due to stretching of the film is suppressed.

[0092] 2) Regarding the process of forming the protrusions Next, the second resin composition is applied (cast) to both ends in the width direction of the surface of the obtained film base 11 to form protrusions.

[0093] The casting of the second resin composition may be by melt casting or by solution casting. For example, if the casting of the first resin composition is carried out by solution casting in step 1) above, it is preferable to carry out the casting of the second resin composition by solution casting in this step.

[0094] In other words, the protrusions 12 can be formed by applying a second resin composition (knurling solution) containing resin and solvent to both ends in the width direction of the film base 11, and then drying it.

[0095] (Second resin composition) The resin contained in the second resin composition is of the same type as the resin contained in the dope.

[0096] The solvent contained in the second resin composition includes at least an organic solvent (good solvent) capable of dissolving the resin. Examples of good solvents include chlorinated organic solvents such as methylene chloride, and non-chlorinated organic solvents such as methyl acetate, ethyl acetate, acetone, tetrahydrofuran, cyclopentanone, and toluene. Among these, methylene chloride, cyclopentanone, and toluene are preferred from the viewpoint of easily dissolving cycloolefin resins.

[0097] The solvent contained in the second resin composition may further contain a poor solvent. The same poor solvent used in the dope can be used as the poor solvent.

[0098] In the solution casting method, the resin concentration of the second resin composition is preferably lower than that of the first resin composition, and 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 greater than 2% by mass and 10% by mass or less, and more preferably 3 to 7% by mass. The height of the protrusions can be adjusted by adjusting the resin concentration of the second resin composition. For example, the height of the protrusions can be increased by increasing the resin concentration of the second resin composition.

[0099] (Grant) The second resin composition can be applied by any method, such as coating using a dispenser or inkjet method, or casting using a die (preferably a vacuum die).

[0100] The temperature of the second resin composition during casting is, for example, 10 to 30°C, preferably room temperature (23°C).

[0101] (Drying) The second resin composition can be dried by any method, such as hot air drying or heating and drying using electromagnetic waves (e.g., heating and drying using an infrared (IR) heater).

[0102] The drying temperature is not particularly limited, but a high temperature is preferred. Specifically, the drying temperature is preferably 40 to (Tg-20)°C, and more preferably 80 to (Tg-10)°C, where Tg is the glass transition temperature of the resin contained in the second resin composition. Specifically, it is preferably 40 to 120°C, and more preferably 80 to 100°C.

[0103] The resulting strip-shaped film 10 may be wound into a roll along its longitudinal direction.

[0104] 3) Regarding the winding process The obtained film base 11 is wound up in the longitudinal direction (a direction perpendicular to the width direction) of the film 10 using a winding machine. This makes it possible to obtain a film roll in which the strip-shaped film 10 is wound up in a roll shape around a winding core.

[0105] The winding method is not particularly limited and can be the constant torque method, constant tension method, tapered tension method, etc.

[0106] The winding tension when winding the film base 11 is not particularly limited, but can be approximately 50 to 170 N.

[0107] The resulting film 10 is used as an optical film for display devices such as liquid crystal displays and organic EL displays, after the portion forming the protrusions 12 is removed during use. Examples of optical films include polarizing plate protective films (including phase difference films and brightness enhancement films), transparent substrate films, and light diffusion films. Among these, film 10 is preferably used as a polarizing plate protective film.

[0108] [Differentiation] In the above embodiment, an example was shown in which multiple island-shaped protrusions 12 are arranged along the longitudinal direction of the film base 11, but the embodiment is not limited to this.

[0109] Figure 3A is a plan view of the modified film, and Figure 3B is a cross-sectional view taken along line 3B-3B in Figure 3A. As shown in Figures 3A and 3B, the protrusions 12 may be arranged continuously (in a strip) along the longitudinal direction of the film base 11.

[0110] Furthermore, although the above embodiment shows an example in which the protrusion 12 is arranged on only one surface of the film base 11, it is not limited to this and may be arranged on both surfaces.

[0111] Furthermore, in the above embodiment, an example was shown in which the protrusions 12 are formed by applying a knurling solution containing resin and solvent and then drying it (solution casting method). However, the invention is not limited to this, and the protrusions may also be formed by applying a molten resin composition and then cooling and solidifying it (molten casting method).

[0112] In other words, in the molten casting method, the roll body can be obtained by 1) casting a molten first resin composition and then cooling and solidifying it to obtain a strip-shaped film base, and 2) applying a molten second resin composition to both ends in the width direction of the strip-shaped film base 11 and then cooling and solidifying it to form protrusions. [Examples]

[0113] The present invention will be specifically described below with reference to examples, but the present invention is not limited to these examples.

[0114] 1. Making a film roll <Preparing Film Roll 1> (Preparation of fine particle dispersion) The following components were mixed and stirred in a dissolver for 50 minutes, and then dispersed in a Manton-Gorin. Furthermore, the mixture was dispersed in an attritor until the secondary particles reached a predetermined size, and then filtered using Finemet NF manufactured by Nippon Seisen Co., Ltd. to prepare a fine particle dispersion. R972V (manufactured by Nippon Aerosil Co., Ltd.): 4% by mass Dichloromethane: 48% by mass Ethanol: 48% by mass

[0115] (Preparation of dope) First, dichloromethane was added to a pressurized dissolution tank at a flow rate of 400 kg / min and ethanol at a flow rate of 20 kg / min. Three minutes after the start of solvent addition, the cyclic polyolefin resin was added to the pressurized dissolution tank while stirring. Next, five minutes after the start of solvent addition, the fine particle additive solution was added and heated to 60°C, and completely dissolved while stirring. The heating temperature was increased from room temperature at a rate of 5°C / min, dissolved for 30 minutes, and then cooled at a rate of 3°C / min. This was filtered using Asaka Filter Paper No. 244 (filtration accuracy 0.005 mm) manufactured by Asaka Filter Paper Co., Ltd. at a flow rate of 300 L / m³. 2 ·h, filtration pressure 1.0×10 6 The mixture was filtered at Pa to prepare a dope with the following composition. Cycloolefin resin G7810 (manufactured by JSR Corporation) (Cycloolefin resin (COP) containing structural units derived from norbornene monomers represented by the following formula, Mw: 140,000, Tg: 170°C): 100% by mass R972V (manufactured by Nippon Aerosil Co., Ltd.): 0.30% by mass Dichloromethane: 380% by mass Ethanol: 20% by mass [ka]

[0116] (Film forming) Next, the obtained dope was uniformly cast onto a stainless steel belt support at a temperature of 31°C and a width of 2300 mm using an endless belt casting apparatus. The temperature of the stainless steel belt was adjusted to 28°C, and the conveying speed of the stainless steel belt was set to 30 m / min. After evaporating the solvent in the cast dope on the stainless steel belt support until the residual solvent content was 30% by mass, the dope was peeled off the stainless steel belt support with a peeling tension of 110 N / m to obtain a film-like material. The obtained film-like material was stretched 1.3 times in the transport direction (MD direction) while heating to 120°C using a roll method that utilizes the difference in peripheral speed of the transport rolls, and then stretched 1.65 times in the TD direction while heating to 130°C using a tenter method. The obtained film-like material was transported while heating to 70°C until completely dry, and the ends were slit to obtain a film with a thickness of 35 μm and a width of 2500 mm (film base, Ro: 50 nm, Rt: 135 nm).

[0117] (Preparation of the solution for forming protrusions) As the same thermoplastic resin as the above film, a cycloolefin resin G7810 (manufactured by JSR Corporation) was dissolved in a solvent to a concentration of 4% by mass to obtain a solution for forming protrusions. The solvent used was a mixed solvent of dichloromethane and cyclopentanone, with a mixing ratio of dichloromethane / cyclopentanone = 70 / 30 (by mass).

[0118] (Formation of protrusions) A convex-forming solution was applied to both ends of the film's surface in the width direction, and then dried to form convex areas. The convex-forming solution was applied using a SUPER HI JET dispenser manufactured by Musashi Engineering Co., Ltd., and discontinuously formed roughly mound-shaped (island-shaped) convex areas with a diameter of 1 mm and a height of 0.5 μm. Specifically, as shown in Figure 2A, the convex areas were formed in three rows along the longitudinal direction of the film (Y direction in Figure 2A), and in the width direction of the film (X direction in Figure 2A), they were formed in a region from 3 mm from the edge of the film to approximately 5 mm towards the center in the width direction. The distance p between the centers of the convex areas was 2 mm in both the X and Y directions. The density of the convex areas 12 was 25 units / cm³. 2 That's what I decided.

[0119] Then, the film with the convex portion formed on it was wound onto a core for a length of 4000m to obtain film roll 1.

[0120] <Preparing film rolls 2-5> Film rolls 2 to 5 were obtained in the same manner as film roll 1, except that the resin concentration of the convex-forming solution and the dispenser head descent speed were adjusted to change the height of the convex as shown in Table 1.

[0121] <Preparing Film Roll 6> (Preparation of UV-curable compositions) A UV-curable composition containing the following components was prepared. Dipentaerythritol hexaacrylate (DPHA, manufactured by Nippon Kayaku): 100 parts by mass Methyl ethyl ketone: 113 parts by mass Photopolymerization initiator (Irgacure 907, manufactured by Ciba-Gaiky): 3 parts by mass

[0122] (Formation of protrusions) Film roll 6 was obtained by forming protrusions in the same manner as film roll 1, except that after applying the above UV-curable composition, the protrusions were formed by curing with UV light.

[0123] <Preparing Film Roll 7> (Preparation of the film base) A film to serve as the film base was obtained using the same method as for film roll 1.

[0124] (Knurling (embossing)) A film roll 7 was obtained by applying a knurling (embossing) process with a width of 10 mm and a height of 2 μm to both ends of the surface of the above film in the width direction (a region 1 to 2 mm from the edge of the film). The knurling process was performed by applying pressure to a metal ring having a heated uneven pattern (a shape in which nine uneven areas are connected in the width direction). The processing pressure of the metal ring was 200 kPa and the temperature was 230°C. The resulting film base had a thin section.

[0125] <Preparing Film Roll 8> (Preparation of the film base) A film to serve as the film base was obtained using the same method as for film roll 1.

[0126] (Knurling process (laser irradiation)) A film roll 8 was obtained by irradiating the surface of the above film at both ends in the width direction with laser light using a laser marker to form an uneven surface. The uneven surface was formed in a region 1 to 2 mm from the edge of the film, with the shape, size, and spacing shown in Figure 4. The resulting film base had a thin section. A CO2 laser irradiation device (LP-430U, Panasonic Sunkus Co., Ltd., laser wavelength 10.6 μm) was used as the laser irradiation device. The laser irradiation output was set to 90%.

[0127] <Preparing Film Roll 9> Film roll 9 was obtained in the same manner as film roll 2, except that the width of the protrusion and the haze ratio were changed as shown in Table 1.

[0128] <Preparation of film roll 11> Film roll 11 was obtained in the same manner as film roll 2, except that the thickness of the film base was changed as shown in Table 1.

[0129] <Preparation of film rolls 10 and 12> (Preparation of the film base) A film base (film base, Ro: 5nm, Rt: -5nm) was obtained in the same manner as film roll 1, except that the cycloolefin resin G7810 (COP) was changed to a (meth)acrylic resin (Acr) (PMMA, Mw: 800,000).

[0130] (Preparation of the solution for forming protrusions) The protrusions were formed in the same manner as in film roll 1, except that the cycloolefin resin G7810 in the solution for forming the protrusions was replaced with the above-mentioned (meth)acrylic resin, and the resin concentration was adjusted so that the height of the protrusions was the value shown in Table 1.

[0131] <Rating> Furthermore, the shape of the protrusions on the obtained film rolls 1 to 12 and the deformation of the film rolls were evaluated using the following method.

[0132] (1) Height t of the convex part, haze ratio Hz2 / Hz1 The height t (maximum height) and width w (maximum width) of the protrusions in the cross-section of the film in the width direction were measured using a laser microscope. A Keyence VK-X1000 laser microscope was used. Specifically, the height t and width w of the protrusions were measured over a range of 100 mm in the length direction and 15 mm in the width direction of the film in the region where the protrusions were located, and the average values ​​of these measurements were defined as "height t and width w of the protrusions".

[0133] The haze value Hz1 of region a1 on the film where no protrusions are present, and the haze value Hz2 of region a2 where protrusions are present (measurement area Φ11m, area 95mm²). 2 The values ​​were measured using an NDH2000 manufactured by Nippon Denshoku Industries Co., Ltd., and their ratio was calculated as the haze ratio Hz2 / Hz1.

[0134] (2) Winding deformation The wound film roll was double-wrapped in polyethylene sheets, and both ends of the core were supported by a stand (so that the axis of the winding core was horizontal). It was stored for 5 days under conditions of 40°C and 80% humidity. After that, the polyethylene sheets were removed, and the surface of the film roll was illuminated by reflecting the light from a lit fluorescent lamp, and any distortion or fine irregularities were observed. The film was then evaluated based on the following criteria. ◎: Fluorescent lights appear straight. ○: There is one spot where the fluorescent light appears slightly bent, but it does not pose any practical problems. △: There are two places where the fluorescent light appears slightly bent, but this does not pose a practical problem. ×: There are areas where the fluorescent light is clearly bent and areas where the light is patchy, which is a problem. A score of △ or higher was considered acceptable.

[0135] (3) Interlayer contact (blocking) The wound film roll was double-wrapped in polyethylene sheets, and with both ends of the core supported by a stand (so that the axis of the winding core was horizontal), it was stored for 5 days under conditions of 40°C and 80% humidity. After that, the film was unwound from the roll, and the blocking (adhesion) state of the overlapping films was visually observed. The film was then evaluated based on the following criteria. ◎: No blocking ○: There is some blocking, but it is very slight and does not pose a practical problem. △: There is slight blocking, but it does not pose a practical problem. ×: Blocking is clearly visible at a glance. A score of △ or higher was considered acceptable.

[0136] (4) Adhesion of the protruding part A vibration test was conducted on the wound film roll, measuring 5.8 m / s. 2 An acceleration was applied in the width direction for 30 minutes. The vibration testing machine used was the TR1000 manufactured by IMV Corporation. Afterwards, the film was unwound from the roll, and the presence or absence of any areas where the protrusions had peeled away from the film base was visually checked for 100m of film between 300m and 200m remaining on the core. The film was then evaluated based on the following criteria. ◎: No peeling ○: Peeling in 1-2 places is not a problem. △: There are 3-4 areas of peeling, but it does not pose a practical problem. ×: There are 5 or more areas of peeling, which is a practical problem. A score of △ or higher was considered acceptable.

[0137] (5) Microscopic foreign matter A vibration test was conducted on the wound film roll, measuring 5.8 m / s. 2 An acceleration was applied in the width direction for 30 minutes. The vibration testing machine used was the TR1000 manufactured by IMV Corporation. Afterwards, the film was unwound from the roll, sampled, and the vicinity of knurling was observed with an optical microscope. The following determination was made. ◎: No minute fragments present. ○: There are a very small number of tiny fragments, but it does not pose a practical problem. △: There are a few tiny fragments, but it does not affect practical use. ×: There are many tiny fragments, which is a problem. A score of △ or higher was considered acceptable.

[0138] (6) Display quality of 8K LCD display (Fabrication of polarizing plates) A 100 μm thick amorphous polyester film was subjected to corona treatment on one side. An aqueous solution containing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified polyvinyl alcohol (Nippon Synthetic Chemical Industry "Gosephymer Z200"; degree of polymerization 1200, degree of acetoacetyl modification 4.6%, degree of saponification 99.0 mol% or more) in a mass ratio of 9:1 was applied to the treated surface at 25°C and dried to obtain a laminate containing an amorphous polyester film substrate and an 11 μm thick PVA-based resin layer.

[0139] The obtained laminate was uniaxially stretched at its free end to a 2.0x ratio in the longitudinal direction by air-assisted stretching in an oven at 120°C. Then, while being conveyed on a roll, it was sequentially immersed in a 4% boric acid aqueous solution at 30°C for 30 seconds, and then in a dyeing solution (0.2% iodine, 1.0% potassium iodide aqueous solution) at 30°C for 60 seconds. Next, while being conveyed on a roll, the laminate was immersed in a crosslinking solution (3% potassium iodide, 3% boric acid aqueous solution) at 30°C for 30 seconds to perform a crosslinking treatment, and then uniaxially stretched at its free end in the longitudinal direction to a total stretching ratio of 5.5x while being immersed in a 4% boric acid, 5% potassium iodide aqueous solution at 70°C. After that, the laminate was immersed in a washing solution (4% potassium iodide aqueous solution) at 30°C to obtain a laminate containing an amorphous polyester film substrate and a 5 μm thick PVA-based polarizer.

[0140] (Preparation of active energy ray curing adhesive composition) As an active energy ray-curable adhesive composition, we prepared one with the following composition. N-hydroxyethylacrylamide: 30 parts by mass Acryloylmorpholine: 65 parts by mass Tripropylene glycol diacrylate: 5 parts by mass 2,4-Diethylthioxanthene-9-one (initiator): 1.4 parts by mass 2-Methyl-1-(4-methylthiophenyl)-2-morpholinopropan-1-one: 1.4 parts by mass The above curable adhesive composition is applied to the surface of the polarizer of the laminate to a thickness of approximately 1 μm, and the film unwound from the film roll is then bonded thereto, with an integrated light intensity of 1000 mJ / cm². 2 The adhesive was cured by irradiating it with ultraviolet light. The bonding was performed so that the slow axis of the film and the absorption axis of the polarizer were perpendicular to each other.

[0141] An amorphous polyester film substrate was peeled from the laminate, the active energy ray curable adhesive composition was applied to the surface of the peeled PVA resin layer, and the film was bonded to it. The adhesive was then cured by irradiation with ultraviolet light. As a result, a polarizing plate was obtained having a polarizer and the above-mentioned film as a polarizing plate protective film arranged on both sides thereof.

[0142] The obtained polarizing plates were then used in an 8K liquid crystal display panel, and the uniformity of light leakage during black display was visually evaluated. Specifically, a 20 μm thick acrylic adhesive sheet was laminated using a roll laminator to the film on the side of the polarizing plate where the slow axis was perpendicular to the absorption axis of the polarizer, thereby obtaining a polarizing plate with an adhesive layer.

[0143] (Fabrication of liquid crystal display devices) (A) When using a polarizing plate containing COP film The polarizing plates that were attached to both sides of the liquid crystal cell of a Sharp 60-inch LCD display 8T-C60BW1 (VA type) were removed. The adhesive layer of the polarizing plate with adhesive sheet that was prepared above was attached to both sides of the liquid crystal cell. The orientation of the slow axis of the above film and the absorption axis of the polarizer were made to match the orientation of the polarizing plate that was originally attached.

[0144] (B) When using a polarizing plate containing Acr film The system was manufactured in the same manner as described above, except that the Sharp 60-inch LCD display 8T-C60BW1 was replaced with an LG Electronics 65-inch LCD display 65NANO99JNA (IPS type).

[0145] (Light leakage when displaying black) The obtained 8K liquid crystal display was placed in a darkroom and converted to a completely black display via external input from a PC. Furthermore, the edges on all four sides were sealed with black tape to ensure that only the black display area was visible when viewed from the front. In this state, the unevenness of light leakage was observed and evaluated based on the following criteria. ◎: There is very little unevenness in light leakage. ○: There is only slight unevenness in light leakage. △: There is some unevenness in light leakage, but it does not affect practical use. ×: There is a lot of uneven light leakage, making it unsuitable for practical use. A score of △ or higher was considered acceptable.

[0146] Table 1 shows the manufacturing conditions and evaluation results for film rolls 1 to 12.

[0147] [Table 1]

[0148] As shown in Table 1, film rolls 1-3 and 9-11 (the present invention) all exhibit no foreign matter generation, winding failures, or detachment of protrusions. This also demonstrates that light leakage during black display can be suppressed.

[0149] In contrast, in film rolls 5 and 12, where the height of the protrusions is greater than 3 μm, the rate of deformation of the protrusions is high, making them prone to winding deformation. This results in variations in the optical properties of the film, leading to light leakage when displaying black. On the other hand, in film roll 4, where the height of the protrusions is less than 0.5 μm, film adhesion (blocking) is more likely to occur, resulting in light leakage when displaying black. Furthermore, it can be seen that even with a low height of the protrusions, interlayer adhesion can be highly suppressed by increasing the haze ratio (comparison of film rolls 9 and 2).

[0150] Furthermore, film rolls 7 and 8 have a Hz2 / Hz1 ratio higher than 4.5, indicating that they are prone to foreign matter and winding deformation, which can lead to light leakage when displaying black. This is thought to be because the convex portions are formed using plastic deformation above Tg, making them susceptible to minute voids. These voids reduce the strength of the convex portions, causing them to slightly collapse when rolled. When the convex portions collapse, minute foreign matter is generated, making them prone to scratches. The collapse of the convex portions also causes winding deformation, resulting in minute wrinkles and impaired optical uniformity of the film, which is thought to lead to uneven light leakage in the display device.

[0151] Furthermore, in the film roll 6 where the resin constituting the protrusions is the same UV-curable resin that makes up the film base, the protrusions fall off, impairing the knurling function and causing light leakage when displaying black.

[0152] This application claims priority under Japanese Patent Application No. 2021-011192, filed on 27 January 2021. All information contained in the specification and drawings of said application is incorporated herein by reference. [Industrial applicability]

[0153] According to the present invention, it is possible to provide a film and a film roll that can suppress blocking and deterioration of winding shape during storage of films such as optical films, and reduce variations in optical properties. [Explanation of Symbols]

[0154] 10. Strip-shaped film (film roll) 11 Film base 12 Convex part

Claims

1. It is film, It includes a strip-shaped film base and a plurality of protrusions that are coated and formed on both ends of the surface of the film base in the width direction and are arranged along the length direction of the film base. The multiple protrusions provided at both ends in the width direction are arranged in multiples in the width direction. The film base and the protrusions contain the same type of thermoplastic resin. The film base and the protrusion may each further contain fine particles, and If the protrusion contains fine particles, the amount of fine particles in the protrusion is less than the amount of fine particles in the film base. The height of the aforementioned protrusion is 0.5 to 3 μm. When the haze value of the region of the film where the protrusions are not arranged is Hz1, and the haze value of the region where the protrusions are arranged is Hz2, the haze ratio Hz2 / Hz1 is 1.2 to 4.

5. film.

2. The film base does not have a thin portion. The film according to claim 1.

3. The aforementioned protrusions are arranged in multiple island-like configurations. The film according to claim 1 or 2.

4. The film base and the protrusion are integrally formed. The film according to any one of claims 1 to 3.

5. The thickness of the film base is 10 to 40 μm. The film according to any one of claims 1 to 4.

6. The thermoplastic resin is a cycloolefin resin or a (meth)acrylic resin. The film according to any one of claims 1 to 5.

7. The film base is an optical film. The film according to any one of claims 1 to 6.

8. A film comprising any one of claims 1 to 7, Film roll.

9. A method for manufacturing a film according to any one of claims 1 to 7, 1) A step of casting the first resin composition to obtain a strip-shaped film base, 2) A step of applying the second resin composition to both ends in the width direction of the surface of the strip-shaped film base to form a protrusion, including, A method for manufacturing film.

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