KR20240020193A - Method for manufacturing machined film and machined film - Google Patents

Abstract

The present invention provides a method for producing a cut film that can produce a cut film having a cross section with excellent straightness (linearity).
The method for producing a cutting film according to an embodiment of the present invention includes a step of cutting the cross-section of the film using a front framing, and the feed speed of the front framing in the cutting process is 800 mm/min or less.

Description

Manufacturing method of cutting film and cutting film {METHOD FOR MANUFACTURING MACHINED FILM AND MACHINED FILM}

The present invention relates to a method for producing a cutting film and a cutting film.

There is a risk that irregularities such as hangnails may appear on the cross section of the film during the production of the film. For this reason, it is known to improve the smoothness of the cross-section of the film by cutting with a cross-section cutting device (for example, see Patent Document 1). In recent years, there has been a demand for improvement in the positional accuracy of members in various industrial products, and along with this, there has been a demand for improvement in the precision of the shape of the outer edge of the film used in the product. In particular, there are cases where excellent linearity (straightness) of the cross section of the film is required, and there remains room for improvement in improving the straightness of the cross section of the film.

Japanese Patent Publication No. 2018-103276

The present invention was made to solve the above-described conventional problems, and its main purpose is to manufacture a cutting film capable of producing a cutting film having a cross-section with excellent straightness (straightness). The point is to provide a method.

[1] The method of manufacturing a cutting film according to an embodiment of the present invention includes a process of cutting the cross-section of the film by front fraise, and the feed speed of the front fraise in the cutting process is is less than 800mm/min.

[2] In the method for producing a cutting film according to [1] above, the film includes a first film; an adhesive layer laminated on the first film; It is a laminated film including a second film attached to the first film via the adhesive layer, and the feed speed of the front frame in the cutting process may be 400 mm/min or more.

[3] In the method for producing a cutting film described in [2] above, the first film may be a polarizer, and the second film may be a retardation layer.

[4] In the method for producing a cutting film according to any one of [1] to [3] above, in the cutting process, the cross section is formed so that the straightness of the cross section according to the following straightness measurement is 0.007 mm or less. You may perform cutting processing.

Straightness measurement;

Measure the coordinates of the cross section at 10 points using a computer numerically controlled image measurement system, calculate an approximation line from the coordinates of the 10 points, and calculate the difference between the maximum and minimum values of the interval between the approximation line and the cross section in the direction perpendicular to the approximation line. is taken as straightness.

[5] The cut film according to another aspect of the present invention has a cross-section cut by a front fray, and the straightness of the cross-section according to the straightness measurement is 0.007 mm or less.

According to the embodiment of the present invention, the straightness (linearity) in the cross section of the cut film can be improved.

1 is a plan view of a laminated film used in a method for producing a cutting film according to one embodiment of the present invention.
FIG. 2 is a schematic cross-sectional view of the laminated film of FIG. 1.

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

(Definition of terms and symbols)

The definitions of terms and symbols in this specification are as follows.

(1) Refractive index (nx, ny, nz)

'nx' is the refractive index in the direction in which the in-plane refractive index is maximum (i.e., the slow axis direction), and 'ny' is the refractive index in the direction perpendicular to the slow axis in the plane (i.e., the fast axis). direction), and 'nz' is the refractive index in the thickness direction.

(2) In-plane phase difference (Re)

'Re(λ)' is the in-plane phase difference measured with light with a wavelength of λ nm at 23°C. For example, 'Re(550)' is the in-plane phase difference measured with light with a wavelength of 550 nm at 23°C. Re(λ) can be obtained by the formula: Re(λ)=(nx-ny)×d, when the thickness of the layer (film) is d (nm).

(3) Phase difference in the thickness direction (Rth)

'Rth(λ)' is the phase difference in the thickness direction measured with light with a wavelength of λ nm at 23°C. For example, 'Rth(550)' is the phase difference in the thickness direction measured with light with a wavelength of 550 nm at 23°C. Rth(λ) can be obtained by the formula: Rth(λ)=(nx-nz)×d, when the thickness of the layer (film) is d (nm).

(4) Nz coefficient

The Nz coefficient can be obtained by Nz=Rth/Re.

(5) angle

When an angle is mentioned herein, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Therefore, for example, '45°' means ±45°.

A. Overview of the manufacturing method of the cutting film

1 is a top view of a laminated film used in a method for producing a machined film according to one embodiment of the present invention; Figure 2 is a schematic cross-sectional view of the laminated film of Figure 1.

The method of manufacturing a cutting film according to an embodiment of the present invention includes a step of cutting the cross section of the film 100 using a front fuse (cutting step). In the cutting process, the front frame moves relative to the cross section of the film 100 to cut the cross section of the film 100. In this way, a machined film having a cross section (cut surface) machined by a front frame is manufactured. The feed speed of the front frame in the cutting process (relative moving speed with respect to the cross section of the film) is 800 mm/min or less, preferably 750 mm/min or less, and typically 200 mm/min or more, preferably 300 mm/min. or more, more preferably 400 mm/min or more. If the feed speed of the front frame is below the above upper limit, the straightness of the cut surface of the cut film can be improved.

Straightness is an indicator of linearity and is typically measured by the following straightness measurement.

Straightness measurement;

The coordinates of the cross section of the film are measured at 10 points using a computer numerically controlled image measurement system, an approximation line is calculated from the coordinates of those 10 points, and the maximum value of the interval between the approximation line and the cross section of the film in the direction perpendicular to the approximation line is calculated. The difference between the minimum values is taken as straightness. More specifically, in the direction perpendicular to the approximation line, the interval between each of the 10 previously measured points and the calculated approximation line is calculated, and the difference between the maximum and minimum values of those intervals is taken as the straightness (=maximum value - minimum value). . A representative computer numerical control image measurement system is NEXIV (trade name) manufactured by Nikon.

The straightness of the cut surface of the cut film is typically 0.0070 mm or less, preferably 0.0065 mm or less, and more preferably 0.0060 mm or less. If the straightness on the cutting surface is below the above upper limit, the cutting film can be positioned based on the cutting surface when applying the cutting film to various industrial products (typically image display devices). For this reason, the relative positional accuracy between the cutting film and other members can be improved. The lower limit of straightness on the cutting surface is typically 0 mm or more, for example, 0.0010 mm or more. That is, in the cutting process, the cross-section of the film is cut so that the straightness of the cross-section is below the above upper limit.

B. Details of the film

In one embodiment, the film cut in the cutting process includes a first film 11; an adhesive layer 41 laminated on the first film 11; It is a laminated film 100 including a second film 2 affixed to the first film 11 via an adhesive layer 41 . Even in the case where the cross section of the laminated film containing the adhesive layer is cut by the front frame, if the feed speed of the front frame is more than the above lower limit, defects in the adhesive layer (adhesive absence) during the cutting process can be stably suppressed. there is.

As shown in FIG. 2, the laminated film 100 according to one embodiment includes a polarizing plate 1 including a polarizer 11 as an example of the first film; a first adhesive layer 41 laminated on the polarizer 11; The first retardation layer 2 is an example of the second film, and is attached to the polarizer 11 via the first adhesive layer 41; a second retardation layer (3) attached to the first retardation layer (2) via an adhesive layer (7); It is provided with a second adhesive layer (42) laminated on the second phase difference layer (3). A release liner 5 may be temporarily attached to the surface of the second adhesive layer 42 in a peelable manner. A surface protection film 6 may be affixed to the surface of the polarizing plate 1 opposite to the first retardation layer 2. That is, the laminated film 100 in the illustrated example is an optical laminated body, including a surface protection film 6; Polarizer (1) and; a first adhesive layer (41); a first phase difference layer (2); Adhesive layer (7); a second phase difference layer (3); a second adhesive layer (42); The release liners 5 are provided in this order.

The total thickness of the laminated film 100 is, for example, 10 μm or more, preferably 50 μm or more, for example, 200 μm or less, preferably 150 μm or less.

The laminated film 100 can have any appropriate shape as long as it includes a cross-section that extends linearly when viewed from the film thickness direction (lamination direction). The shape of the laminated film is typically a polygonal shape, preferably a square shape. The laminated film 100 shown in FIG. 1 has a rectangular shape when viewed from the film thickness direction (lamination direction). In the laminated film of the example shown, the dimension of the long side is typically 50 mm or more and 500 mm or less, and the dimension of the short side is typically 10 mm or more and 200 mm or less.

Hereinafter, the components of the laminated film 100 will be described in more detail.

B-1. polarizer

B-1-1. polarizer

As the polarizer 11, any suitable polarizer can be employed. For example, the resin film forming the polarizer may be a single-layer resin film or a laminate of two or more layers.

Specific examples of polarizers composed of a single-layer resin film include hydrophilic polymer films such as polyvinyl alcohol (PVA)-based films, partially formalized PVA-based films, and partially saponified ethylene-vinyl acetate copolymer-based films, and iodine and dichroic dyes. Examples include polyene-based oriented films, such as those that have been dyed and stretched with dichroic substances, and those that have been treated with dehydration of PVA and those with dehydrochloride treatment of polyvinyl chloride. Preferably, a polarizer obtained by dyeing a PVA-based film with iodine and uniaxially stretching is used because it has excellent optical properties.

The dyeing with iodine is performed, for example, by immersing the PVA-based film in an aqueous iodine solution. The draw ratio of the uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after dyeing treatment or may be performed while dyeing. Additionally, it may be dyed after stretching. If necessary, swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. are performed on the PVA-based film. For example, by immersing the PVA-based film in water and washing it before dyeing, it is possible to not only clean the surface of the PVA-based film from contamination and anti-blocking agents, but also to swell the PVA-based film to prevent staining, etc.

Specific examples of the polarizer obtained using the laminate include a laminate of a resin substrate and a PVA-based resin layer (PVA-based resin film) laminated on the resin substrate, or a laminate of a resin substrate and a PVA-based resin layer applied to the resin substrate. A polarizer obtained by using a laminated body can be mentioned. A polarizer obtained using a laminate of a resin substrate and a PVA-based resin layer formed by applying to the resin substrate is, for example, applied by applying a PVA-based resin solution to a resin substrate, drying it, and forming a PVA-based resin layer on the resin substrate, Obtaining a laminate of a resin substrate and a PVA-based resin layer; It can be produced by stretching and dyeing the laminate and using the PVA-based resin layer as a polarizer. In one embodiment of the present invention, a polyvinyl alcohol-based resin layer containing a halide and a polyvinyl alcohol-based resin is preferably formed on one side of the resin substrate. Stretching typically includes stretching the laminate by immersing it in an aqueous boric acid solution. Additionally, stretching, if necessary, may further include air stretching the laminate at a high temperature (for example, 95°C or higher) before stretching in an aqueous boric acid solution. In addition, in one embodiment of the present invention, the laminate is preferably subjected to a dry shrink treatment in which the laminate is shrunk by 2% or more in the width direction by heating while conveying in the longitudinal direction. Typically, the manufacturing method of this embodiment includes performing aerial auxiliary stretching treatment, dyeing treatment, underwater stretching treatment, and dry shrink treatment on the laminate in this order. By introducing auxiliary stretching, even when applying PVA on a thermoplastic resin, it becomes possible to increase the crystallinity of PVA and achieve high optical properties. Moreover, by increasing the orientation of PVA in advance at the same time, problems such as a decrease in orientation or dissolution of PVA when immersed in water in the later dyeing process or stretching process can be prevented, making it possible to achieve high optical properties. I do it. Additionally, when the PVA-based resin layer is immersed in a liquid, the disruption of the orientation of polyvinyl alcohol molecules and the decrease in orientation can be suppressed compared to the case where the PVA-based resin layer does not contain a halide. Thereby, the optical properties of the polarizer obtained through a treatment process performed by immersing the laminate in a liquid, such as dyeing treatment and underwater stretching treatment, can be improved. Additionally, optical properties can be improved by shrinking the laminate in the width direction through dry shrinkage treatment. The obtained resin substrate/polarizer laminate may be used as is (i.e., the resin substrate may be used as a protective layer for the polarizer), or the resin substrate may be peeled from the resin substrate/polarizer laminate and applied to the peeled surface for the purpose. Any appropriate protective layer may be laminated and used. Details of the manufacturing method of such a polarizer are described in, for example, Japanese Patent Application Laid-Open No. 2012-73580 and Japanese Patent Application Publication No. 6470455. The entire description of these publications is incorporated herein by reference.

The thickness of the polarizer is, for example, 1 μm to 80 μm, preferably 1 μm to 15 μm, more preferably 1 μm to 12 μm, further preferably 3 μm to 12 μm, and especially preferably 3 μm to 12 μm. It is ㎛~8㎛. If the thickness of the polarizer is within this range, curling during heating can be suppressed satisfactorily, and good external appearance durability during heating can be obtained.

The polarizer preferably exhibits absorption dichroism at any wavelength between 380 nm and 780 nm. The single transmittance of the polarizer is, for example, 41.5% to 46.0%, preferably 43.0% to 46.0%, and more preferably 44.5% to 46.0%. The polarization degree of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and even more preferably 99.9% or more.

B-1-2. protective layer

As shown in FIG. 2 , the polarizing plate 1 may be provided with a protective layer 12 in addition to the polarizer 11 . The protective layer 12 is provided on at least one side of the polarizer 11. The protective layer 12 in the illustrated example is disposed on the side opposite to the first retardation layer 2 with respect to the polarizer 11. The protective layer 12 is typically bonded to the polarizer 11 via any suitable adhesive layer (not shown).

The protective layer is formed from any suitable film that can be used as a protective layer for a polarizer. Specific examples of materials that become the main components of the film include cycloolefin (COP)-based such as polynorbornene-based, polyester-based such as polyethylene terephthalate (PET)-based, cellulose-based resin such as triacetylcellulose (TAC), and polycarbonate. Transparent resins such as (PC)-based, (meth)acrylic-based, polyvinyl alcohol-based, polyamide-based, polyimide-based, polyethersulfone-based, polysulfone-based, polystyrene-based, polyolefin-based, and acetate-based resins can be mentioned. In addition, thermosetting resins or ultraviolet curing resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, silicone, etc. may also be included. In addition, '(meth)acrylic resin' refers to acrylic resin and/or methacrylic resin. In addition, for example, glassy polymers such as siloxane polymers can also be mentioned. Additionally, the polymer film described in Japanese Patent Application Laid-Open No. 2001-343529 (WO01/37007) can also be used. As a material for this film, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in the side chain and a thermoplastic resin having a substituted or unsubstituted phenyl group and a nitrile group in the side chain can be used, for example, isobutene and A resin composition containing an alternating copolymer containing N-methylmaleimide and an acrylonitrile/styrene copolymer can be mentioned. The polymer film may be, for example, an extrusion molded product of the resin composition. The materials for the resin film can be used individually or in combination.

Additionally, the protective layer 2 may be subjected to surface treatment such as hard coat treatment, anti-reflection treatment, anti-sticking treatment, or anti-glare treatment as needed. Additionally, the protective layer 12 may be treated, as necessary, to improve visibility when viewed through polarized sunglasses (typically, imparting an (other) circularly polarized light function or imparting an ultra-high phase difference. ) may be implemented.

The thickness of the protective layer is typically 5 mm or less, preferably 1 mm or less, more preferably 1 μm to 500 μm, and still more preferably 5 μm to 150 μm.

B-2. First phase contrast layer and second phase contrast layer

The first retardation layer 2 is bonded to the polarizing plate 1 (polarizer 11) via the first adhesive layer 41. The second retardation layer 3 is located on the side opposite to the polarizing plate 1 with respect to the first retardation layer 2, and is bonded to the first retardation layer 2 via an adhesive layer 7.

The first phase difference layer 2 and the second phase difference layer 3 are each typically an alignment-fixed layer of a liquid crystal compound. By using a liquid crystal compound, the difference between nx and ny of the resulting retardation layer can be significantly increased compared to a non-liquid crystal material, so the thickness of the retardation layer for obtaining the desired in-plane retardation can be significantly reduced. As a result, significant thinning of the polarizing plate with a retardation layer can be realized. In this specification, the term 'alignment-fixed layer' refers to a layer in which a liquid crystal compound is oriented in a predetermined direction within the layer, and its orientation state is fixed. In addition, the 'alignment solidified layer' is a concept that includes an alignment hardened layer obtained by curing a liquid crystal monomer, as will be described later. In the first retardation layer 2 and the second retardation layer 3, typically, rod-shaped liquid crystal compounds are aligned in the slow axis direction of the first retardation layer or the second retardation layer (homogeneous orientation) ).

Examples of the liquid crystal compound include a liquid crystal compound (nematic liquid crystal) whose liquid crystal phase is a nematic phase. As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The mechanism for expressing liquid crystallinity of the liquid crystal compound may be lyotropic or thermotropic. The liquid crystal polymer and liquid crystal monomer may be used individually or in combination.

When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer or a crosslinkable monomer. This is because the alignment state of the liquid crystal monomer can be fixed by polymerizing or crosslinking (i.e., curing) the liquid crystal monomer. After aligning the liquid crystal monomers, for example, by polymerizing or crosslinking the liquid crystal monomers, the alignment state can be fixed accordingly. Here, polymers are formed by polymerization and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystalline. Therefore, the formed retardation layer is unlikely to transition into a liquid crystal phase, a glass phase, or a crystal phase due to temperature changes peculiar to liquid crystalline compounds, for example. As a result, the phase difference layer becomes a phase difference layer that is not affected by temperature changes and has extremely excellent stability.

The temperature range in which a liquid crystal monomer exhibits liquid crystallinity varies depending on its type. Specifically, the temperature range is preferably 40°C to 120°C, more preferably 50°C to 100°C, and most preferably 60°C to 90°C.

As the liquid crystal monomer, any suitable liquid crystal monomer may be employed. For example, polymerization described in Japanese Patent Application Publication 2002-533742 (WO00/37585), EP358208 (US5211877), EP66137 (US4388453), WO93/22397, EP0261712, DE19504224, DE4408171, and GB2280445. Sexual mesogenic compounds can be used. Specific examples of such polymerizable mesogenic compounds include, for example, BASF's trade name LC242, Merck's trade name E7, and Wacker-Chem's trade name LC-Sillicon-CC3767. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable.

The liquid crystal alignment solidification layer performs an orientation treatment on the surface of a predetermined substrate, applies a coating liquid containing a liquid crystal compound to the surface, orients the liquid crystal compound in a direction corresponding to the orientation treatment, and maintains the orientation state. It can be formed by fixing it. In one embodiment, the substrate is any suitable resin film, and the liquid crystal alignment solidification layer (first retardation layer 2) formed on the substrate is formed on the surface of the polarizing plate 1 via the first adhesive layer 41. can be transcribed. Likewise, the liquid crystal alignment solidification layer (second retardation layer 3) formed on the substrate can be transferred to the surface of the first retardation layer 2 via the adhesive layer 7.

As the orientation treatment, any appropriate orientation treatment may be employed. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment can be mentioned. Specific examples of mechanical orientation treatment include rubbing treatment and stretching treatment. Specific examples of physical alignment treatment include magnetic field alignment treatment and electric field alignment treatment. Specific examples of chemical alignment treatment include oblique vapor deposition and photo-alignment treatment. The treatment conditions for various orientation treatments may be any appropriate conditions depending on the purpose.

The alignment of the liquid crystal compound is achieved by treatment at a temperature that exhibits a liquid crystal phase depending on the type of the liquid crystal compound. By performing such temperature treatment, the liquid crystal compound assumes a liquid crystal state, and the liquid crystal compound is aligned according to the orientation treatment direction of the substrate surface.

In one embodiment, the alignment state is fixed by cooling the liquid crystal compound aligned as described above. When the liquid crystal compound is a polymerizable monomer or a crosslinkable monomer, the alignment state is fixed by subjecting the liquid crystal compound oriented as described above to polymerization treatment or crosslinking treatment.

Specific examples of the liquid crystal compound and details of the method for forming the alignment solidification layer are described in Japanese Patent Application Laid-Open No. 2006-163343. The description in this publication is incorporated herein by reference.

The first retardation layer and the second retardation layer each typically exhibit a relationship of nx>ny=nz in refractive index characteristics. Additionally, 'ny=nz' includes not only the case where ny and nz are completely the same, but also the case where they are substantially the same. Therefore, there may be cases where ny > nz or ny < nz within a range that does not impair the effect of the present invention.

Typically, either the first phase difference layer 2 or the second phase difference layer 3 may function as a λ/2 plate, and the other may function as a λ/4 plate. Here, a case is described where the first phase difference layer 2 can function as a λ/2 plate and the second phase difference layer 3 can function as a λ/4 plate, but these may be reversed. In the case where the first retardation layer 2 can function as a λ/2 plate and the second retardation layer 3 can function as a λ/4 plate, the in-plane retardation Re( 550) is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, and even more preferably 250 nm to 280 nm. The angle formed by the slow axis of the first retardation layer 2 and the absorption axis of the polarizer 11 is preferably 10° to 20°, more preferably 12° to 18°, and even more preferably about 15°. It is °. The in-plane phase difference Re(550) of the second phase difference layer 3 is preferably 100 nm to 190 nm, more preferably 110 nm to 170 nm, and still more preferably 130 nm to 160 nm. The angle formed by the slow axis of the second retardation layer 3 and the absorption axis of the polarizer 11 is preferably 70° to 80°, more preferably 72° to 78°, and even more preferably about 75°. It is °. With such a configuration, it is possible to obtain characteristics close to ideal reverse wavelength dispersion characteristics, and as a result, very excellent anti-reflection characteristics can be realized.

The thickness of the first retardation layer 2 can be adjusted to obtain the desired in-plane retardation of the λ/2 plate, and can be, for example, 1.5 μm to 2.5 μm. The thickness of the second retardation layer 3 can be adjusted to obtain the desired in-plane retardation of the λ/4 plate, and can be, for example, 0.5 μm to 1.5 μm.

The first phase difference layer and the second phase difference layer each have an Nz coefficient of preferably 0.9 to 1.5, and more preferably 0.9 to 1.3. By satisfying this relationship, when the resulting cut film is used in an image display device, very excellent reflected color can be achieved.

The first phase difference layer and the second phase difference layer may each exhibit inverse dispersion wavelength characteristics in which the phase difference value increases depending on the wavelength of the measurement light, or may exhibit positive wavelength dispersion characteristics in which the phase difference value decreases depending on the wavelength of the measurement light. Alternatively, the phase difference value may exhibit flat wavelength dispersion characteristics that hardly change depending on the wavelength of the measurement light.

B-3. adhesive layer

The adhesive layer 7 bonds the first retardation layer 2 and the second retardation layer 3 together. As the adhesive constituting the adhesive layer, any suitable adhesive may be employed. Representative examples of adhesives include active energy ray-curable adhesives. Examples of active energy ray-curable adhesives include ultraviolet ray-curable adhesives and electron beam-curable adhesives. Additionally, from the viewpoint of the curing mechanism, examples of active energy ray curable adhesives include radical curing type, cation curing type, anion curing type, and hybrid of radical curing type and cation curing type. Typically, a radical curing type ultraviolet curing type adhesive can be used. This is because it has excellent versatility and the characteristics (configuration) can be easily adjusted. The thickness of the adhesive layer (after adhesive curing) is typically 0.1 μm to 3.0 μm. Details of the adhesive are described in, for example, Japanese Patent Application Publication No. 2018-017996. The description in this publication is incorporated herein by reference.

B-4. adhesive layer

The first adhesive layer 41 is located between the polarizer 11 and the first retardation layer 2, and bonds them together. The second adhesive layer 42 is provided on the surface of the second retardation layer 3 opposite to the first retardation layer 2.

The storage elastic modulus of each of the first adhesive layer 41 and the second adhesive layer 42 at 25°C is preferably 1.0×10 ⁴ Pa to 1.0×10 ⁶ Pa, more preferably 1.0×10 It is ⁴ Pa~2.0×10 ⁵ Pa. If the storage modulus of the adhesive layer is in this range, defects in the adhesive layer can be stably suppressed during the cutting process.

Each of the first adhesive layer 41 and the second adhesive layer 42 is made of adhesive. As the adhesive, any suitable composition may be employed. Specific examples of the adhesive constituting the adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. By adjusting the type, number, combination and mixing ratio of the monomers forming the base resin of the adhesive, the amount of crosslinking agent, reaction temperature, reaction time, etc., an adhesive having desired properties according to the purpose can be prepared. The base resin of the adhesive may be used individually, or may be used in combination of two or more types. From the viewpoints of transparency, processability, durability, etc., an acrylic adhesive (acrylic adhesive composition) is preferable. Acrylic adhesive compositions typically contain a (meth)acrylic polymer as a main component. The (meth)acrylic polymer may be contained in the adhesive composition at a rate of, for example, 50% by mass or more, preferably 70% by mass or more, and more preferably 90% by mass or more, of the solid content of the adhesive composition. The (meth)acrylic polymer contains alkyl (meth)acrylate as a main component as a monomer unit. Additionally, (meth)acrylate refers to acrylate and/or methacrylate. The alkyl (meth)acrylate may be contained in a proportion of preferably 80% by mass or more, more preferably 90% by mass or more, among the monomer components forming the (meth)acrylic polymer. Examples of the alkyl group of the alkyl (meth)acrylate include a straight-chain or branched alkyl group having 1 to 18 carbon atoms. The average number of carbon atoms of the alkyl group is preferably 3 to 9, more preferably 3 to 6. A preferred alkyl (meth)acrylate is butyl acrylate. Monomers (copolymerized monomers) constituting the (meth)acrylic polymer include, in addition to alkyl (meth)acrylates, monomers containing carboxyl groups, monomers containing hydroxyl groups, monomers containing amide groups, (meth)acrylates containing aromatic rings, and heterocycles. and vinyl-containing monomers. Representative examples of copolymerized monomers include acrylic acid, 4-hydroxybutylacrylate, phenoxyethyl acrylate, and N-vinyl-2-pyrrolidone. The acrylic adhesive composition may preferably contain a silane coupling agent and/or a crosslinking agent. Examples of the silane coupling agent include epoxy group-containing silane coupling agents. Examples of crosslinking agents include isocyanate-based crosslinking agents and peroxide-based crosslinking agents. Additionally, the acrylic adhesive composition may contain an antioxidant and/or a conductive agent. Details of the adhesive layer or acrylic adhesive composition are, for example, Japanese Patent Application Laid-Open No. 2006-183022, Japanese Patent Application Publication No. 2015-199942, Japanese Patent Application Laid-Open No. 2018-053114, Japanese Patent Application Publication No. 2016-190996, International Publication No. It is described in No. 2018/008712, and the descriptions of these publications are incorporated herein by reference.

The thickness of the first adhesive layer 41 is, for example, 3 μm to 30 μm, and is preferably 5 μm to 20 μm. The thickness of the second adhesive layer 42 is, for example, 5 μm to 40 μm, and is preferably 10 μm to 20 μm.

B-5. surface protection film

In the illustrated example, the surface protection film 6 is affixed to the protective layer 12 of the polarizing plate 1. The surface protection film 6 typically includes a base material 61 and an adhesive layer 62. Examples of the material of the base material 61 include those similar to the resin constituting the protective layer 12. The adhesive layer 62 attaches the base material 61 of the surface protection film 6 to the protective layer 12 . The adhesive layer 62 is explained similarly to the adhesive layers 41 and 42 described above.

B-6. release liner

The release liner 5 is temporarily attached to the surface of the second adhesive layer 42 . The release liner 5 is formed of any suitable resin film that can be used as a release liner. Specific examples of materials that serve as the main component of the resin film include polyethylene terephthalate (PET), polyethylene, and polypropylene. The materials for the resin film can be used individually or in combination. A release treatment layer may be provided on the contact surface of the release liner 5 with the second adhesive layer 42. Examples of the release treatment agent that forms the release treatment layer include a silicone-based release treatment agent, a fluorine-based release treatment agent, and a long-chain alkyl acrylate-based release agent. The mold release treatment agent can be used individually or in combination.

The thickness of the release liner 5 is, for example, 5 μm to 60 μm, and is preferably 20 μm to 45 μm. In addition, when a release treatment layer is applied, the thickness of the release liner is a thickness including the thickness of the release treatment layer.

C. Details of cutting process

In one embodiment, in the cutting process, the cross section of the above-described laminated film 100 is cut by using a front fuse. This cutting process can be performed using any suitable cross-sectional cutting equipment. Examples of the cross-sectional cutting device include the cross-sectional cutting device described in Japanese Patent Application Publication No. 2018-103276. This publication is hereby incorporated by reference in its entirety.

In the cutting process, the front frame moves relative to the cross section of the laminated film 100 at the above-mentioned feed rate. The front frame may be moved while the laminated film 100 is fixed to the single-sided cutting machine, or the laminated film 100 may be moved while the front frame is fixed. The front frame typically moves around the film 100 fixed to the single-sided cutting device in one direction (preferably clockwise or counterclockwise in plan view) at the above-mentioned feed rate, The entire cross section of the laminated film 100 is cut.

In the cutting process, the front frame rotates around an axis extending in a direction perpendicular to the lamination direction of the laminated film 100. The rotation speed of the front phrase is typically 3000 rpm to 6000 rpm, and preferably 4000 rpm to 5000 rpm.

The number of blades of the front phrase is not particularly limited, and is, for example, 1 to 5, preferably 2 to 4.

The cutting angle (radial rake angle) at the front frame is typically 5° to 35°, and preferably 10° to 30°.

The mounting angle (axial rake angle) in the front frame is typically 0° to 20°, and preferably 5° to 15°.

The relief angle in the front frame is typically 1° to 20°, and preferably 1° to 10°.

If the cutting process is performed under the above conditions, the straightness of the cut cross section (cut surface) can be stably improved. In this way, a cut film (cut laminated film) is manufactured. At least one of the cut surfaces of the cut film (cut laminated film) has a straightness in the above-mentioned range. In the rectangular cut film (cut laminated film) of the example shown, the cut surface on the short side preferably has a straightness in the above range. The straightness of the cutting surface on the long side may be within the above range or outside the above range. Additionally, the cut surface may have cutting marks caused by front fraying. The cutting mark may extend in a direction intersecting the thickness direction of the film (typically in an arc shape).

D. Image display device

The cutting film (typically a cutting laminated film) described in items A to C above can be applied to an image display device. Accordingly, an image display device including a machining film is also included in embodiments of the present invention. An image display device typically includes an image display cell and a cut film bonded to the image display cell through an adhesive layer. Since the cross-section of the cut film (especially the cut surface on the short side) has excellent straightness, it can be attached to the image display cell using the cross-section of the cut film (particularly the cut surface on the short side) as a reference. As a result, the relative positional accuracy between the image display cell and the cutting film can be improved. When the cut film is a cut laminated film, the cut laminated film is typically affixed to an image display cell with the second adhesive layer after the release liner is peeled from the second adhesive layer. In addition, the surface protection film may be peeled off before use of the cutting laminated film, or may be used in a state affixed to the surface of the polarizing plate. Representative examples of image display devices include liquid crystal display devices and electroluminescence (EL) display devices (eg, organic EL display devices and inorganic EL display devices).

[Example]

Hereinafter, the present invention will be specifically described based on examples, but the present invention is not limited to these examples. The measurement method for each characteristic is as follows. In addition, unless otherwise specified, 'part' and '%' in Examples and Comparative Examples are based on mass.

(1) Thickness

The thickness of 10 μm or less was measured using an interference thickness meter (manufactured by Otsuka Electronics, product name ‘MCPD-3000’). Thickness exceeding 10㎛ was measured using a digital micrometer (manufactured by Anritsu, product name 'KC-351C').

(2) Straightness

For each of the 20 samples of the cutting film (optical laminate) of Examples and Comparative Examples, the straightness was calculated as follows. The coordinates of the cross section on the short side of the cut film were measured at 10 points using a computer numerical control image measurement system (manufactured by Nikon, product name 'NEXIV'), and an approximation line was calculated from the coordinates of the 10 points. Next, the difference between the maximum and minimum values of the interval between the approximation line and the cross section (specifically, each of the 10 points previously measured) in the direction perpendicular to the approximation line (long side direction) was taken as straightness.

In addition, the straightness of the 20 samples in each example (or Comparative Example 1) was subjected to a rejection test using the Smirnov Grubbs test, excluding data where the straightness reached a rejection value (p<0.05). , the average value of straightness was calculated. In Examples 1 and 2, the average value of 18 samples was calculated excluding the 2 samples that were rejected. In Examples 3 and 4, the average value of 19 samples excluding 1 sample that was rejected was calculated. In Comparative Example 1, since there were no rejection values, the average value of 20 samples was calculated. The results are shown in Table 1.

(3) Lifting of the surface protective film (SPV lifting)

The cut films (optical laminates) of the examples and comparative examples were observed from the surface protection film side with an optical microscope, and the lifting of the surface protection film was measured.

○ (Right): SPV lifting is 50㎛ or less.

△ (A): SPV lifting exceeds 50㎛.

(4) Defect of adhesive layer (lack of adhesive)

The cut films (optical laminates) of the examples and comparative examples were observed under an optical microscope with the surface protection film peeled off, and defects in the adhesive layer were measured.

○ (right): Lack of adhesive is 70 μm or less.

△(a): Lack of adhesive exceeds 70㎛.

[Preparation example 1]

1. Production of polarizer

As a thermoplastic resin substrate, an amorphous isophthalic copolymerization polyethylene terephthalate film (thickness: 100 μm), which is long and has a Tg of about 75°C, was used, and corona treatment was performed on one side of the resin substrate.

100 parts by mass of PVA-based resin mixed at 9:1 with polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Japan Synthetic Chemical Industry Co., Ltd., brand name ‘Gosephimer’), potassium iodide 13 The added mass was dissolved in water to prepare a PVA aqueous solution (coating solution).

The PVA aqueous solution was applied to the corona-treated surface of the resin substrate and dried at 60°C to form a PVA-based resin layer with a thickness of 13 μm, thereby producing a laminate.

The obtained laminate was uniaxially stretched 2.4 times in the longitudinal direction (longitudinal direction) in an oven at 130°C (air auxiliary stretching treatment).

Next, the laminate was immersed in an insolubilization bath (boric acid aqueous solution obtained by mixing 4 parts by mass of boric acid with 100 parts by mass of water) at a liquid temperature of 40°C for 30 seconds (insolubilization treatment).

Next, in a dyeing bath (iodine aqueous solution obtained by mixing iodine and potassium iodide at a weight ratio of 1:7 with respect to 100 parts by mass of water) at a liquid temperature of 30°C, the single transmittance (Ts) of the polarizer finally obtained is the desired value. It was immersed for 60 seconds while adjusting the concentration as much as possible (dyeing treatment).

Next, it was immersed in a crosslinking bath (a boric acid aqueous solution obtained by mixing 3 parts by mass of potassium iodide and 5 parts by mass of boric acid with respect to 100 parts by mass of water) at a liquid temperature of 40°C for 30 seconds (crosslinking treatment).

Thereafter, the laminate was immersed in an aqueous boric acid solution (boric acid concentration: 4% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70°C, and the total stretch ratio was stretched in the longitudinal direction (longitudinal direction) between rolls with different circumferential speeds. Uniaxial stretching was performed to increase the size by 5.5 times (underwater stretching treatment).

Thereafter, the laminate was immersed in a washing bath (an aqueous solution obtained by mixing 4 parts by mass of potassium iodide with 100 parts by mass of water) at a liquid temperature of 20°C (washing treatment).

Afterwards, it was dried in an oven maintained at about 90°C and brought into contact with a heating roll made of SUS whose surface temperature was maintained at about 75°C (dry shrink treatment).

In this way, a polarizer with a thickness of about 5 μm was formed on the resin substrate, and a laminate having a resin substrate/polarizer configuration was obtained.

An HC-TAC film (thickness 20 μm) was bonded to the polarizer surface (surface opposite to the resin substrate) of the obtained laminate as a protective layer. Next, the resin substrate was peeled, and a polarizing plate having a protective layer/polarizer configuration was obtained.

2. Fabrication of the first phase contrast layer and the second phase contrast layer

10 g of a polymerizable liquid crystal exhibiting a nematic liquid crystalline phase (manufactured by BASF, brand name 'Paliocolor LC242', expressed in the formula below), and a photopolymerization initiator for the polymerizable liquid crystal compound (manufactured by BASF, brand name 'Irgacure 907') 3 g was dissolved in 40 g of toluene to prepare a liquid crystal composition (coating solution).

The surface of a polyethylene terephthalate (PET) film (thickness 38 μm) was rubbed using a rubbing cloth to perform an orientation treatment. The direction of the orientation treatment was set to be 15° when viewed from the viewer's side with respect to the direction of the absorption axis of the polarizer when bonding to the polarizing plate. The liquid crystal coating liquid was applied to this alignment treated surface using a bar coater, and the liquid crystal compound was aligned by heating and drying at 90°C for 2 minutes. The liquid crystal layer thus formed was irradiated with light at 1 mJ/cm ² using a metal halide lamp, and the liquid crystal layer was cured, thereby forming a liquid crystal alignment layer A on the PET film. The thickness of the liquid crystal alignment solidification layer A was 2 μm, and the in-plane retardation Re (550) was 270 nm. Additionally, the liquid crystal alignment-fixed layer A had a refractive index distribution of nx>ny=nz. Liquid crystal alignment-fixed layer A was used as the first retardation layer.

Liquid crystal alignment solidification layer B was formed on the PET film in the same manner as above except that the coating thickness was changed and the orientation treatment direction was 75° when viewed from the visual side with respect to the direction of the absorption axis of the polarizer. The thickness of the liquid crystal alignment solidification layer B was 1 μm, and the in-plane retardation Re(550) was 140 nm. Additionally, the liquid crystal alignment-fixed layer B had a refractive index distribution of nx>ny=nz. Liquid crystal alignment-fixed layer B was used as the second phase difference layer.

3. Production of laminate film

The liquid crystal alignment fixed layer A (first phase difference layer) and liquid crystal alignment layer B (second phase difference layer) obtained in above 2. were transferred to the polarizer surface of the polarizing plate obtained in above 1. in this order. At this time, the transfer (lamination) was performed so that the angle between the absorption axis of the polarizer and the slow axis of the orientation-frozen layer A was 15°, and the angle between the absorption axis of the polarizer and the slow axis of the orientation-frozen layer B was 75°. In addition, the liquid crystal alignment solidification layer A (first retardation layer) was transferred (laminated) to the polarizer through an acrylic adhesive layer (thickness 5 μm, storage modulus at 25°C 1.4×10 ⁵ Pa, first adhesive layer). . The liquid crystal alignment solidified layer B (second phase difference layer) was transferred (laminated) to the liquid crystal alignment solidified layer A through an ultraviolet curing adhesive layer (thickness 1.0 μm, adhesive layer). Additionally, an acrylic adhesive layer (thickness 20 μm, storage modulus at 25°C of 1.4×10 ⁵ Pa, second adhesive layer) was placed on the surface of liquid crystal alignment solidification layer B (second retardation layer). After that, a release liner (a polyethylene terephthalate-based resin film provided with a release treatment layer) was attached to the surface of the acrylic adhesive layer (second adhesive layer). Finally, a substrate (polyethylene terephthalate-based resin film); A surface protection film including an acrylic adhesive layer laminated on a base material was affixed to the protective layer of the polarizing plate.

As a result of the above, a laminated film having the structure of surface protection film/polarizing plate/1st adhesive layer/1st retardation layer/adhesive layer/2nd retardation layer/2nd adhesive layer/release liner was obtained. The laminated film had a rectangular shape when viewed from the lamination direction. The dimension of the long side of the laminated film was 200 mm, and the dimension of the short side of the laminated film was 100 mm.

[Examples 1 to 4 and Comparative Example 1]

The laminated film obtained in Preparation Example 1 was set in a single-sided cutting machine. In detail, the two holding parts held the laminated film between them in the thickness direction with a clamp pressure of 0.17 MPa. Next, the cross section of the laminated film was cut with a front fray under the following cutting conditions. In cutting processing, the front frame moved relative to the cross section of the laminated film at the feed rate shown in Table 1. As a result, a cutting film (optical laminate) was obtained. Additionally, at each feed rate, 20 samples (cut film) were prepared.

<Cutting conditions>

Number of blades: 3

Cutting angle/mounting angle/relief angle: 20°/10°/6°

Rotation speed: 4500rpm

Maximum cutting amount: 0.8+0.2mm (2 times machining)

[Table 1]

[evaluation]

As is clear from Table 1, according to the embodiment of the present invention, the straightness of the cross section can be improved by setting the feed speed of the front frame to 800 mm/min or less. Additionally, it can be seen that when the feed speed of the front frame is set to 400 mm/min or more, lifting of the surface protection film and defects in the adhesive layer can be suppressed.

The method for producing a cutting film of the present invention can produce a cutting film used in various industrial products, especially a cutting laminated film. The cutting laminated film is suitably used in display devices such as liquid crystal display devices, organic EL display devices, and inorganic EL display devices.

1: Polarizer
11: Polarizer
2: First phase contrast layer
41: First adhesive layer
100: Laminated film

Claims (5)

It includes a process of cutting the cross section of the film by front fraise,
A method for producing a cutting film, wherein the feed speed of the front frame in the cutting process is 800 mm/min or less. According to paragraph 1,
The film includes a first film; an adhesive layer laminated on the first film; It is a laminated film including a second film attached to the first film through the adhesive layer,
A method for producing a cutting film, wherein the feed speed of the front frame in the cutting process is 400 mm/min or more. According to paragraph 2,
The first film is a polarizer,
A method of manufacturing a cutting film, wherein the second film is a retardation layer. According to paragraph 1,
In the cutting process, the cross-section is cut so that the straightness of the cross-section according to the following straightness measurement is 0.007 mm or less:
(Straightness measurement - Measure the coordinates of the cross section at 10 points using a computer numerical control image measurement system, calculate an approximation line from the coordinates of the 10 points, and determine the distance between the approximation line and the cross section in a direction perpendicular to the approximation line. The difference between the maximum and minimum values of the interval is considered straightness.) A cut film having a cross-section cut by a front frame, and the straightness of the cross-section according to the following straightness measurement is 0.007 mm or less:
(Straightness measurement - Measure the coordinates of the cross section at 10 points using a computer numerical control image measurement system, calculate an approximation line from the coordinates of the 10 points, and determine the distance between the approximation line and the cross section in a direction perpendicular to the approximation line. The difference between the maximum and minimum values of the interval is considered straightness.)