JP2024022329A - Manufacturing method of cutting processed film and cutting processed film - Google Patents

Abstract

An object of the present invention is to provide a method for producing a cut film that can produce a cut film having an end face with excellent straightness (linearity). A method for manufacturing a cut film according to an embodiment of the present invention includes a step of cutting an end face of the film with a face milling cutter, and the feed rate of the face milling cutter in the cutting step is 800 mm/min or less. . [Selection diagram] Figure 1

Description

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

There is a possibility that irregularities such as cracks may occur on the end face of the film during film production. Therefore, it is known that the smoothness of the end face of the film is improved by cutting using an end face cutting device (for example, see Patent Document 1). In recent years, it has been desired to improve the positional accuracy of members in various industrial products, and along with this, there has been a demand for improved accuracy in the outer edge shape of films used in the products. In particular, excellent linearity (straightness) is sometimes required at the end faces of the film, but there is still room for improvement in improving the straightness of the end faces of the film.

Japanese Patent Application Publication No. 2018-103276

The present invention has been made to solve the above-mentioned conventional problems, and its main purpose is to provide a method for producing a cut film that can produce a cut film having an end face with excellent straightness (linearity). It's about doing.

[1] The method for producing a cut film according to an embodiment of the present invention includes a step of cutting the end face of the film with a face milling cutter, and the feed rate of the face milling cutter in the cutting step is 800 mm/min or less.
[2] In the method for producing a cut film according to [1] above, the film includes: a first film; an adhesive layer laminated on the first film; and the first film via the adhesive layer. The laminated film may include a second film attached to the film, and the feed rate of the face milling cutter in the cutting process may be 400 mm/min or more.
[3] In the method for manufacturing a cut film according to [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 cut film according to any one of [1] to [3] above, in the cutting step, the straightness of the end face as measured by the following straightness measurement is 0.007 mm or less. , the end face may be cut.
Straightness measurement;
The coordinates of the end face are measured at 10 points using a computer numerically controlled image measurement system, an approximate line is calculated from the coordinates of the 10 points, and the maximum value of the distance between the approximate line and the end face in the direction orthogonal to the approximate line is calculated. The difference from the minimum value is taken as straightness.
[5] A cut film according to another aspect of the present invention has an end face cut by a face milling cutter, and the straightness of the end face as measured by the straightness measurement described above is 0.007 mm or less.

According to the embodiment of the present invention, it is possible to improve the straightness (linearity) of the end face of the cut film.

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

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

(Definition of terms and symbols)
Definitions of terms and symbols used herein 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., slow axis direction), and "ny" is the direction perpendicular to the slow axis in the plane (i.e., fast axis direction) "nz" is the refractive index in the thickness direction.
(2) In-plane phase difference (Re)
"Re(λ)" is an in-plane retardation measured with light having a wavelength of λnm at 23°C. For example, "Re(550)" is an in-plane retardation measured with light having a wavelength of 550 nm at 23°C. Re(λ) is determined by the formula: Re(λ)=(nx−ny)×d, where d (nm) is the thickness of the layer (film).
(3) Phase difference in thickness direction (Rth)
"Rth (λ)" is a retardation in the thickness direction measured with light having a wavelength of λ nm at 23°C. For example, "Rth (550)" is the retardation in the thickness direction measured with light having a wavelength of 550 nm at 23°C. Rth(λ) is determined by the formula: Rth(λ)=(nx−nz)×d, where d (nm) is the thickness of the layer (film).
(4) Nz coefficient The Nz coefficient is determined by Nz=Rth/Re.
(5) Angle When an angle is referred to in this specification, the angle includes both clockwise and counterclockwise directions with respect to the reference direction. Therefore, for example, "45°" means ±45°.

A. Outline of the method for producing a cut film FIG. 1 is a plan view of a laminated film used in the method for producing a cut film according to one embodiment of the present invention; FIG. 2 is a schematic cross-sectional view of the laminated film of FIG. 1. .
The method for producing a cut film according to the embodiment of the present invention includes a step of cutting the end face of the film 100 with a face mill (cutting step). In the cutting process, the face milling cutter cuts the end surface of the film 100 by moving relative to the end surface of the film 100. Thereby, a cut film having an end face (cut surface) cut by the face milling cutter is manufactured. The feed speed of the face milling cutter (relative movement speed with respect to the end surface of the film) in the cutting process is 800 mm/min or less, preferably 750 mm/min or less, typically 200 mm/min or more, preferably 300 mm/min or more, More preferably it is 400 mm/min or more. If the feed rate of the face milling cutter is at most the above upper limit, it is possible to improve the straightness of the cut surface of the cut film.

Straightness is an index of linearity, and is typically measured by the following straightness measurement.
Straightness measurement;
The coordinates of the end face of the film are measured at 10 points using a computer numerically controlled image measurement system, an approximate line is calculated from the coordinates of those 10 points, and the distance between the approximate line and the end face of the film in the direction orthogonal to the approximate line is calculated. Let the difference between the maximum value and the minimum value be the straightness. More specifically, the distance between each of the 10 previously measured points and the calculated approximate line in the direction perpendicular to the approximate line is calculated, and the difference between the maximum and minimum values of these intervals is calculated as the straightness ( = maximum value - minimum value). The computer numerically controlled image measurement system is typically 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 cut surface is below the above upper limit, the cut film can be positioned with the cut surface as a reference when the cut film is employed in various industrial products (typically, image display devices). Therefore, it is possible to improve the relative positional accuracy between the cut film and other members. The lower limit of straightness on the cut surface is typically 0 mm or more, and for example 0.0010 mm or more. That is, in the cutting process, the end face of the film is cut so that the straightness of the end face is equal to or less than the above upper limit.

B. Details of Film In one embodiment, the film cut in the cutting process includes the first film 11; the adhesive layer 41 laminated on the first film 11; and the first film 11 via the adhesive layer 41. This is a laminated film 100 including a second film 2 attached to a second film 2; Even when the end face of the laminated film including the adhesive layer is cut by a face milling cutter, if the feed speed of the face milling cutter is higher than the above lower limit, chipping of the adhesive layer (adhesive chipping) may occur during the cutting process. Can be stably suppressed.

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 a first film; a first adhesive layer 41 laminated on the polarizer 11; A first retardation layer 2 as an example of two films, which is attached to the polarizer 11 via a first adhesive layer 41; It includes a second retardation layer 3 attached to the retardation layer 2; and a second adhesive layer 42 laminated on the second retardation layer 3. A release liner 5 may be temporarily attached to the surface of the second adhesive layer 42 in a releasable manner. A surface protection film 6 may be attached to the surface of the polarizing plate 1 opposite to the first retardation layer 2 . That is, the laminated film 100 of the illustrated example is an optical laminate, and includes the surface protection film 6; the polarizing plate 1; the first adhesive layer 41; the first retardation layer 2; the adhesive layer 7; The second retardation layer 3; the second adhesive layer 42; and the release liner 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, and, for example, 200 μm or less, preferably 150 μm or less.

The laminated film 100 can have any suitable shape as long as it has an end face that extends linearly when viewed from the thickness direction (laminated direction) of the film. The shape of the laminated film is typically polygonal, preferably quadrangular. The laminated film 100 shown in FIG. 1 has a rectangular shape when viewed from the film thickness direction (laminated direction). In the illustrated laminated film, the long side size is typically 50 mm or more and 500 mm or less, and the short side size is typically 10 mm or more and 200 mm or less.

Hereinafter, the constituent elements of the laminated film 100 will be explained in more detail.

B-1. Polarizing plate B-1-1. Polarizer As the polarizer 11, any suitable polarizer may be adopted. 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 made of single-layer resin films include hydrophilic polymer films such as polyvinyl alcohol (PVA) films, partially formalized PVA films, and partially saponified ethylene/vinyl acetate copolymer films. Examples include those that have been dyed and stretched with a dichroic substance such as iodine or dichroic dye, and polyene-based oriented films such as dehydrated PVA and dehydrochloric acid treated polyvinyl chloride. Preferably, a polarizer obtained by dyeing a PVA film with iodine and uniaxially stretching is used because it has excellent optical properties.

The above-mentioned staining with iodine is performed, for example, by immersing the PVA-based film in an iodine aqueous solution. The stretching ratio of the above-mentioned uniaxial stretching is preferably 3 to 7 times. Stretching may be performed after the dyeing process or may be performed while dyeing. Alternatively, it may be dyed after being stretched. If necessary, the PVA film is subjected to swelling treatment, crosslinking treatment, washing treatment, drying treatment, etc. For example, by immersing a PVA film in water and washing it with water before dyeing, you can not only wash dirt and anti-blocking agents from the surface of the PVA film, but also swell the PVA film and prevent uneven dyeing. It can be prevented.

Specific examples of polarizers obtained using a laminate include a laminate of a resin base material and a PVA resin layer (PVA resin film) laminated on the resin base material, or a laminate of a resin base material and the resin Examples include polarizers obtained using a laminate with a PVA-based resin layer coated on a base material. A polarizer obtained using a laminate of a resin base material and a PVA-based resin layer coated on the resin base material can be obtained by, for example, applying a PVA-based resin solution to the resin base material and drying it. Forming a PVA-based resin layer thereon to obtain a laminate of a resin base material and the PVA-based resin layer; stretching and dyeing the laminate to use the PVA-based resin layer as a polarizer; obtain. In one embodiment of the present invention, preferably, a polyvinyl alcohol resin layer containing a halide and a polyvinyl alcohol resin is formed on one side of the resin base material. Stretching typically includes immersing the laminate in an aqueous boric acid solution and stretching. Furthermore, the stretching may further include stretching the laminate in air at a high temperature (for example, 95° C. or higher) before stretching in the boric acid aqueous solution, if necessary. In addition, in one embodiment of the present invention, the laminate is preferably subjected to a drying shrinkage treatment in which the laminate is heated while being conveyed in the longitudinal direction to shrink by 2% or more in the width direction. Typically, the manufacturing method of this embodiment includes subjecting the laminate to an in-air auxiliary stretching process, a dyeing process, an underwater stretching process, and a drying shrinkage process in this order. By introducing auxiliary stretching, even when PVA is applied onto a thermoplastic resin, it becomes possible to improve the crystallinity of PVA and achieve high optical properties. At the same time, by increasing the orientation of PVA in advance, it is possible to prevent problems such as deterioration of orientation and dissolution of PVA when it is immersed in water during the subsequent dyeing and stretching processes, resulting in high optical properties. becomes possible to achieve. Furthermore, when the PVA-based resin layer is immersed in a liquid, disturbance in the orientation of polyvinyl alcohol molecules and deterioration of orientation can be suppressed compared to when the PVA-based resin layer does not contain a halide. This can improve the optical properties of a polarizer obtained through a treatment process performed by immersing the laminate in a liquid, such as dyeing treatment and underwater stretching treatment. Furthermore, optical properties can be improved by shrinking the laminate in the width direction by drying shrinkage treatment. The obtained resin base material/polarizer laminate may be used as is (that is, the resin base material may be used as a protective layer for the polarizer), or the resin base material may be peeled from the resin base material/polarizer laminate. However, any appropriate protective layer may be laminated on the peeled surface depending on the purpose. Details of the method for manufacturing such a polarizer are described in, for example, Japanese Patent Application Publication No. 2012-73580 and Japanese Patent No. 6470455. The entire descriptions of these publications are 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, even more preferably 3 μm to 12 μm, particularly preferably 3 μm to 8 μm. When the thickness of the polarizer is within such a range, curling during heating can be suppressed well, and good appearance durability during heating can be obtained.

The polarizer preferably exhibits absorption dichroism at a wavelength of 380 nm to 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 degree of polarization of the polarizer is preferably 97.0% or more, more preferably 99.0% or more, and still more preferably 99.9% or more.

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

The protective layer is formed of any suitable film that can be used as a protective layer of a polarizer. Specific examples of materials that are the main components of the film include cycloolefin (COP) systems such as polynorbornene systems, polyester systems such as polyethylene terephthalate (PET) systems, cellulose resins such as triacetylcellulose (TAC), and polycarbonate. Examples include transparent resins such as (PC), (meth)acrylic, polyvinyl alcohol, polyamide, polyimide, polyethersulfone, polysulfone, polystyrene, polyolefin, and acetate. Other examples include thermosetting resins such as (meth)acrylic, urethane, (meth)acrylic urethane, epoxy, and silicone resins, and ultraviolet curable resins. Note that "(meth)acrylic resin" refers to acrylic resin and/or methacrylic resin. Other examples include glassy polymers such as siloxane polymers. Furthermore, the polymer film described in JP-A-2001-343529 (WO01/37007) can also be used. Materials for this film include, for example, a resin composition containing a thermoplastic resin having a substituted or unsubstituted imide group in its side chain, and a thermoplastic resin having a substituted or unsubstituted phenyl group and nitrile group in its side chain. For example, a resin composition containing an alternating copolymer of isobutene and N-methylmaleimide and an acrylonitrile/styrene copolymer can be used. The polymer film may be, for example, an extrusion molded product of the resin composition. The materials for the resin film can be used alone or in combination.

Further, the protective layer 12 may be subjected to surface treatments such as hard coat treatment, antireflection treatment, antisticking treatment, and antiglare treatment, as necessary. Additionally/or, the protective layer 12 may be treated as necessary to improve visibility when viewed through polarized sunglasses (typically, imparting (elliptic) circular polarization function, ultra-high retardation ) may be applied.

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 Retardation Layer and Second Retardation 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 opposite side of the polarizing plate 1 with respect to the first retardation layer 2, and is bonded to the first retardation layer 2 via the adhesive layer 7.

Each of the first retardation layer 2 and the second retardation layer 3 is typically an alignment solidified layer of a liquid crystal compound. By using a liquid crystal compound, the difference between nx and ny of the obtained retardation layer can be made much larger than that of non-liquid crystal materials, so the thickness of the retardation layer can be adjusted to obtain the desired in-plane retardation. can be made significantly smaller. As a result, the thickness of the polarizing plate with a retardation layer can be significantly reduced. As used herein, the term "orientation-fixed layer" refers to a layer in which a liquid crystal compound is oriented in a predetermined direction and the orientation state is fixed. In addition, the "alignment hardened layer" is a concept that includes an orientation hardened layer obtained by curing a liquid crystal monomer as described below. In the first retardation layer 2 and the second retardation layer 3, rod-shaped liquid crystal compounds are typically 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 whose liquid crystal phase is a nematic phase (nematic liquid crystal). As such a liquid crystal compound, for example, a liquid crystal polymer or a liquid crystal monomer can be used. The mechanism for developing liquid crystallinity of a liquid crystal compound may be either lyotropic or thermotropic. The liquid crystal polymer and the liquid crystal monomer may be used alone or in combination.

When the liquid crystal compound is a liquid crystal monomer, the liquid crystal monomer is preferably a polymerizable monomer and a crosslinkable monomer. This is because the alignment state of the liquid crystal monomer can be fixed by polymerizing or crosslinking (that is, 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. Here, a polymer is formed by polymerization, and a three-dimensional network structure is formed by crosslinking, but these are non-liquid crystalline. Therefore, the formed retardation layer does not undergo transition to a liquid crystal phase, a glass phase, or a crystalline phase due to a temperature change, which is characteristic of liquid crystal compounds, for example. As a result, the retardation layer becomes an extremely stable retardation layer that is not affected by temperature changes.

The temperature range in which a liquid crystal monomer exhibits liquid crystallinity differs 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.

Any suitable liquid crystal monomer may be employed as the liquid crystal monomer. For example, the Synthetic mesogenic compounds can be used. Specific examples of such polymerizable mesogenic compounds include, for example, BASF's product name LC242, Merck's product name E7, and Wacker-Chem's product name LC-Sillicon-CC3767. As the liquid crystal monomer, for example, a nematic liquid crystal monomer is preferable.

The liquid crystal alignment solidified layer is produced by subjecting the surface of a predetermined base material to an alignment treatment, applying a coating liquid containing a liquid crystal compound to the surface to align the liquid crystal compound in a direction corresponding to the alignment treatment, and forming the liquid crystal alignment layer. It can be formed by fixing the state. In one embodiment, the base material is any suitable resin film, and the liquid crystal alignment solidified layer (first retardation layer 2) formed on the base material is formed on the base material through the first adhesive layer 41. It can be transferred onto the surface of the polarizing plate 1. Similarly, the liquid crystal alignment solidified layer (second retardation layer 3) formed on the base material can be transferred to the surface of the first retardation layer 2 via the adhesive layer 7.

Any suitable orientation treatment may be employed as the orientation treatment. Specifically, mechanical alignment treatment, physical alignment treatment, and chemical alignment treatment can be mentioned. Specific examples of mechanical alignment 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. As the treatment conditions for various orientation treatments, any appropriate conditions may be adopted depending on the purpose.

The alignment of the liquid crystal compound is carried out by treatment at a temperature at which it exhibits a liquid crystal phase depending on the type of liquid crystal compound. By performing such temperature treatment, the liquid crystal compound assumes a liquid crystal state, and the liquid crystal compound is oriented in accordance with the orientation treatment direction of the substrate surface.

In one embodiment, the alignment state is fixed by cooling the liquid crystal compound oriented 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 a polymerization treatment or a crosslinking treatment.

Specific examples of the liquid crystal compound and details of the method for forming the alignment solidified layer are described in JP-A No. 2006-163343. The description of the publication is incorporated herein by reference.

The first retardation layer and the second retardation layer each typically exhibit a refractive index characteristic of nx>ny=nz. Note that "ny=nz" includes not only the case where ny and nz are completely equal but also the case where they are substantially equal. Therefore, there may be cases where ny>nz or ny<nz as long as the effects of the present invention are not impaired.

Typically, either the first retardation layer 2 or the second retardation layer 3 can function as a λ/2 plate, and the other can function as a λ/4 plate. Here, a case will be described in which 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, but these may be reversed. When 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) of the first retardation layer 2 is preferably 200 nm to 300 nm, more preferably 230 nm to 290 nm, even more preferably 250 nm to 280 nm. The angle between 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 still more preferably about 15°. It is. The in-plane retardation Re (550) of the second retardation 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 between 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 still 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, extremely excellent antireflection characteristics can be realized.

The thickness of the first retardation layer 2 may be adjusted to obtain a desired in-plane retardation of the λ/2 plate, and may be, for example, 1.5 μm to 2.5 μm. The thickness of the second retardation layer 3 may be adjusted to obtain a desired in-plane retardation of the λ/4 plate, and may be, for example, 0.5 μm to 1.5 μm.
The first retardation layer and the second retardation layer each preferably have an Nz coefficient of 0.9 to 1.5, more preferably 0.9 to 1.3. By satisfying such a relationship, when the resulting cut film is used in an image display device, it is possible to achieve an extremely excellent reflective hue.

The first retardation layer and the second retardation layer may each exhibit inverse dispersion wavelength characteristics in which the retardation value increases according to the wavelength of the measurement light, and the retardation value decreases according to the wavelength of the measurement light. It may exhibit positive wavelength dispersion characteristics, or it may exhibit flat wavelength dispersion characteristics in which the phase difference value hardly changes 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. Any suitable adhesive may be employed as the adhesive constituting the adhesive layer. Typical examples of the adhesive include active energy ray-curable adhesives. Examples of active energy ray curable adhesives include ultraviolet ray curable adhesives and electron beam curable adhesives. From the viewpoint of the curing mechanism, active energy ray-curable adhesives include, for example, radical-curable adhesives, cation-curable adhesives, anion-curable adhesives, and hybrids of radical-curable and cationic-curable adhesives. Typically, a radical-curable ultraviolet curable adhesive may be used. This is because it has excellent versatility and its characteristics (configuration) can be easily adjusted. The thickness of the adhesive layer (after the adhesive is cured) 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 of the 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 .

Each of the first adhesive layer 41 and the second adhesive layer 42 has a storage modulus at 25° C. of preferably 1.0×10 ⁴ Pa to 1.0×10 ⁶ Pa, more preferably 1.0×10 4 Pa to 1.0×10 6 Pa. It is 0×10 ⁴ Pa to 2.0×10 ⁵ Pa. If the storage elastic modulus of the adhesive layer is within such a range, chipping of the adhesive layer can be stably suppressed in the cutting process.

Each of the first adhesive layer 41 and the second adhesive layer 42 is made of an adhesive. Any suitable configuration may be adopted as the adhesive. Specific examples of adhesives constituting the adhesive layer include acrylic adhesives, rubber adhesives, silicone adhesives, polyester adhesives, urethane adhesives, epoxy adhesives, and polyether adhesives. can be mentioned. By adjusting the type, number, combination, and blending ratio of monomers that form the base resin of the adhesive, as well as the amount of crosslinking agent, reaction temperature, reaction time, etc., adhesives can have the desired characteristics depending on the purpose. can be prepared. The base resin of the adhesive may be used alone or in combination of two or more. From the viewpoints of transparency, processability, durability, etc., acrylic adhesives (acrylic adhesive compositions) are preferred. The acrylic pressure-sensitive adhesive composition typically contains a (meth)acrylic polymer as a main component. The (meth)acrylic polymer may be contained in the adhesive composition in a proportion of, for example, 50% by mass or more, preferably 70% by mass or more, more preferably 90% by mass or more, based on the solid content of the adhesive composition. The (meth)acrylic polymer contains alkyl (meth)acrylate as a main component as a monomer unit. Note that (meth)acrylate refers to acrylate and/or methacrylate. The alkyl (meth)acrylate may be contained in a monomer component forming the (meth)acrylic polymer in a proportion of preferably 80% by mass or more, more preferably 90% by mass or more. Examples of the alkyl group of the alkyl (meth)acrylate include linear or branched alkyl groups having 1 to 18 carbon atoms. The average number of carbon atoms in the alkyl group is preferably 3 to 9, more preferably 3 to 6. A preferred alkyl (meth)acrylate is butyl acrylate. In addition to alkyl (meth)acrylates, the monomers (comonomers) constituting (meth)acrylic polymers include carboxyl group-containing monomers, hydroxyl group-containing monomers, amide group-containing monomers, aromatic ring-containing (meth)acrylates, Examples include ring-containing vinyl monomers. Representative examples of copolymerizable monomers include acrylic acid, 4-hydroxybutyl acrylate, phenoxyethyl acrylate, and N-vinyl-2-pyrrolidone. The acrylic pressure-sensitive 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 the crosslinking agent include isocyanate crosslinking agents and peroxide crosslinking agents. Furthermore, the acrylic adhesive composition may contain an antioxidant and/or a conductive agent. Details of the adhesive layer or the acrylic adhesive composition can be found in, for example, JP2006-183022A, JP2015-199942A, JP2018-053114A, JP2016-190996A, International Publication No. 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, preferably 5 μm to 20 μm. The thickness of the second adhesive layer 42 is, for example, 5 μm to 40 μm, preferably 10 μm to 20 μm.

B-5. Surface Protection Film In the illustrated example, the surface protection film 6 is attached 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 for the base material 61 include the same resin as the protective layer 12 . The adhesive layer 62 adheres the base material 61 of the surface protection film 6 to the protective layer 12. The adhesive layer 62 will be explained in the same manner as 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. Release liner 5 is formed of any suitable resin film that can be used as a release liner. Specific examples of the material that is the main component of the resin film include polyethylene terephthalate (PET), polyethylene, and polypropylene. The materials for the resin film can be used alone or in combination. A release treatment layer may be provided on the surface of the release liner 5 that comes into contact with the second adhesive layer 42 . Examples of the mold release treatment agent forming the mold release treatment layer include silicone mold release treatment agents, fluorine mold release treatment agents, and long chain alkyl acrylate release agents. The mold release treatment agents can be used alone or in combination.

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

C. Details of Cutting Process In one embodiment, in the cutting process, the end face of the above-described laminated film 100 is cut using a face milling cutter. Such a cutting step may be performed by any suitable end face cutting device. Examples of the end face cutting apparatus include the end face cutting apparatus described in JP-A No. 2018-103276. This publication is incorporated herein by reference in its entirety.

In the cutting process, the face milling cutter moves relative to the end surface of the laminated film 100 at the above-described feed rate. The face milling cutter may be moved while the laminated film 100 is fixed to the end face cutting device, or the laminated film 100 may be moved while the face milling cutter is fixed. Typically, the face milling cutter moves in one direction (preferably clockwise or counterclockwise in plan view) around the film 100 fixed to the end face cutting device at the above feed rate. , the entire end surface of the laminated film 100 is cut.

In the cutting process, the face milling cutter rotates around an axis extending in a direction perpendicular to the lamination direction of the laminated film 100. The rotational speed of the face milling cutter is typically between 3000 rpm and 6000 rpm, preferably between 4000 rpm and 5000 rpm.
The number of blades of the face milling cutter is not particularly limited, and is, for example, 1 to 5, preferably 2 to 4.
The rake angle (radial rake angle) in a face mill is typically 5° to 35°, preferably 10° to 30°.
The mounting angle (axial rake angle) in a face mill is typically 0° to 20°, preferably 5° to 15°.
The clearance angle in face milling is typically between 1° and 20°, preferably between 1° and 10°.

When the cutting process is carried out under the above conditions, the straightness of the cut end face (cutting 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 straightness within the above range. In the illustrated example of a rectangular cut film (cut laminated film), the cut surface on the short side preferably has straightness within the above range. The straightness of the machined surface on the long side may be within the above range or may be outside the above range. Further, the cut surface may have cutting marks caused by a face milling cutter. The cutting marks may extend in a direction (typically in an arc shape) intersecting the thickness direction of the film.

D. Image display device The cut film (typically a cut laminated film) described in the above sections A to C can be applied to an image display device. Therefore, an image display device including a cut film is also included in the 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 via an adhesive layer. The edge face of the cut film (especially the cut face on the short side) has excellent straightness, so it can be pasted to the image display cell using the end face of the cut film (especially the cut face on the short side) as a reference. It can be attached. Therefore, it is possible to improve the relative positional accuracy between the image display cell and the cut film. When the machined film is a machined laminate film, the machined laminate film is typically applied to the image display cell by the second adhesive layer after the release liner is peeled from the second adhesive layer. . Further, the surface protection film may be peeled off before using the cut laminated film, or may be used while being attached to the surface of the polarizing plate. Typical 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).

EXAMPLES Hereinafter, the present invention will be specifically explained with reference to Examples, but the present invention is not limited to these Examples. The method for measuring each characteristic is as follows. Note that unless otherwise specified, "parts" and "%" in Examples and Comparative Examples are based on mass.
(1) Thickness The thickness of 10 μm or less was measured using an interference film thickness meter (manufactured by Otsuka Electronics Co., Ltd., product name “MCPD-3000”). Thickness exceeding 10 μm was measured using a digital micrometer (manufactured by Anritsu Corporation, product name “KC-351C”).
(2) Straightness The straightness was calculated as follows for each of the 20 samples of cut films (optical laminates) of Examples and Comparative Examples. The coordinates of the end face on the short side of the cut film were measured at 10 points using a computer numerically controlled image measurement system (manufactured by Nikon, product name "NEXIV"), and an approximate line was calculated from the coordinates of the 10 points. Next, the difference between the maximum value and the minimum value of the interval between the approximate line and the end face (specifically, each of the 10 points measured earlier) in the direction perpendicular to the approximate line (long side direction) is determined as the straightness. And so.
In addition, the straightness of the 20 samples in each Example (or Comparative Example 1) was subjected to a rejection test using the Smirnov-Grabbs test, and the data for which the straightness was a rejection value (p<0.05) was excluded, and the straightness was The average value of the degree was calculated. In Examples 1 and 2, the average value of 18 samples excluding 2 samples that were critical values was calculated. In Example 3 and Example 4, the average value of 19 samples was calculated, excluding one sample that was a rejection value. In Comparative Example 1, there was no critical value, so the average value of 20 samples was calculated. The results are shown in Table 1.
(3) Lifting of surface protection film (SPV lifting)
The cut films (optical laminates) of Examples and Comparative Examples were observed from the surface protection film side using an optical microscope, and the length of the surface protection film was measured.
〇 (Excellent): SPV lifting is 50 μm or less.
△ (Acceptable): SPV lifting exceeds 50 μm.
(4) Chips in the adhesive layer (chips in the adhesive)
The cut films (optical laminates) of Examples and Comparative Examples were observed with an optical microscope with the surface protection film removed, and the length of the adhesive layer was measured.
〇 (Excellent): Adhesive chipping is 70 μm or less.
△ (Acceptable): Adhesive chipping exceeds 70 μm.

[Preparation example 1]
1. Preparation of polarizing plate A long, amorphous isophthalic polyethylene terephthalate film (thickness: 100 μm) with a Tg of approximately 75°C was used as the thermoplastic resin base material, and one side of the resin base material was subjected to corona treatment. was applied.
100 parts by mass of a PVA resin prepared by mixing polyvinyl alcohol (degree of polymerization 4200, degree of saponification 99.2 mol%) and acetoacetyl-modified PVA (manufactured by Nippon Gosei Kagaku Kogyo Co., Ltd., trade name "Gosefaimer") at a ratio of 9:1. to which 13 parts by mass of potassium iodide was added 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 base material 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 vertical direction (longitudinal direction) in an oven at 130° C. (in-air auxiliary stretching treatment).
Next, the laminate was immersed for 30 seconds in an insolubilization bath (boric acid aqueous solution obtained by blending 4 parts by mass of boric acid with 100 parts by mass of water) at a liquid temperature of 40° C. (insolubilization treatment).
Next, the final polarizer was added to a dyeing bath (an iodine aqueous solution obtained by blending iodine and potassium iodide at a weight ratio of 1:7 to 100 parts by mass of water) at a liquid temperature of 30°C. The sample was immersed for 60 seconds while adjusting the concentration so that the single transmittance (Ts) became a desired value (staining treatment).
Next, it was immersed in a crosslinking bath (boric acid aqueous solution obtained by blending 3 parts by mass of potassium iodide and 5 parts by mass of boric acid with 100 parts by mass of water) at a liquid temperature of 40 °C for 30 seconds. (Crosslinking treatment).
Thereafter, while immersing the laminate in a boric acid aqueous solution (boric acid concentration: 4% by weight, potassium iodide concentration: 5% by weight) at a liquid temperature of 70°C, the laminate was completely rolled in the longitudinal direction (longitudinal direction) between rolls having different circumferential speeds. Uniaxial stretching was performed so that the stretching ratio was 5.5 times (underwater stretching treatment).
Thereafter, the laminate was immersed in a cleaning bath (an aqueous solution obtained by blending 4 parts by mass of potassium iodide with 100 parts by mass of water) at a liquid temperature of 20° C. (cleaning treatment).
Thereafter, while drying in an oven kept at about 90°C, it was brought into contact with a SUS heating roll whose surface temperature was kept at about 75°C (drying shrinkage treatment).
In this way, a polarizer with a thickness of about 5 μm was formed on the resin base material, and a laminate having a resin base material/polarizer configuration was obtained.
An HC-TAC film (thickness: 20 μm) was attached as a protective layer to the polarizer surface (the surface opposite to the resin base material) of the obtained laminate. Next, the resin base material was peeled off to obtain a polarizing plate having a protective layer/polarizer/structure.

ポリエチレンテレフタレート（ＰＥＴ）フィルム（厚み３８μｍ）表面を、ラビング布を用いてラビングし、配向処理を施した。配向処理の方向は、偏光板に貼り合わせる際に偏光子の吸収軸の方向に対して視認側から見て１５°方向となるようにした。この配向処理表面に、上記液晶塗工液をバーコーターにより塗工し、９０℃で２分間加熱乾燥することによって液晶化合物を配向させた。このようにして形成された液晶層に、メタルハライドランプを用いて１ｍＪ/ｃｍ^２の光を照射し、当該液晶層を硬化させることによって、ＰＥＴフィルム上に液晶配向固化層Ａを形成した。液晶配向固化層Ａの厚みは２μｍ、面内位相差Ｒｅ（５５０）は２７０ｎｍであった。さらに、液晶配向固化層Ａは、ｎｘ＞ｎｙ＝ｎｚの屈折率分布を有していた。液晶配向固化層Ａを第１位相差層として用いた。
塗工厚みを変更したこと、および、配向処理方向を偏光子の吸収軸の方向に対して視認側から見て７５°方向となるようにしたこと以外は上記と同様にして、ＰＥＴフィルム上に液晶配向固化層Ｂを形成した。液晶配向固化層Ｂの厚みは１μｍ、面内位相差Ｒｅ（５５０）は１４０ｎｍであった。さらに、液晶配向固化層Ｂは、ｎｘ＞ｎｙ＝ｎｚの屈折率分布を有していた。液晶配向固化層Ｂを第２位相差層として用いた。 2. Preparation of the first retardation layer and the second retardation layer: 10 g of polymerizable liquid crystal exhibiting a nematic liquid crystal phase (manufactured by BASF, trade name "Paliocolor LC242", represented by the following formula) and light directed against the polymerizable liquid crystal compound. A liquid crystal composition (coating liquid) was prepared by dissolving 3 g of a polymerization initiator (trade name: "Irgacure 907" manufactured by BASF) in 40 g of toluene.

The surface of a polyethylene terephthalate (PET) film (thickness: 38 μm) was rubbed using a rubbing cloth to perform orientation treatment. The orientation treatment direction was set to be 15 degrees from the viewing side with respect to the direction of the absorption axis of the polarizer when bonding to the polarizing plate. The above-mentioned liquid crystal coating solution 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 thus formed liquid crystal layer was irradiated with light of 1 mJ/cm ² using a metal halide lamp to cure the liquid crystal layer, thereby forming a liquid crystal alignment solidified layer A on the PET film. The thickness of the liquid crystal alignment solidified layer A was 2 μm, and the in-plane retardation Re (550) was 270 nm. Furthermore, the liquid crystal alignment solidified layer A had a refractive index distribution of nx>ny=nz. The liquid crystal alignment solidified layer A was used as the first retardation layer.
The coating was applied on the PET film in the same manner as above, except that the coating thickness was changed and the orientation treatment direction was set at 75° when viewed from the viewing side with respect to the direction of the absorption axis of the polarizer. A liquid crystal alignment solidified layer B was formed. The thickness of the liquid crystal alignment solidified layer B was 1 μm, and the in-plane retardation Re (550) was 140 nm. Furthermore, the liquid crystal alignment solidified layer B had a refractive index distribution of nx>ny=nz. The liquid crystal alignment solidified layer B was used as the second retardation layer.

3. Preparation of laminate film 1. The above 2. is applied to the polarizer surface of the polarizing plate obtained in 2. The liquid crystal alignment fixed layer A (first retardation layer) and the liquid crystal alignment fixed layer B (second retardation layer) obtained in step 1 were transferred in this order. At this time, the angle between the absorption axis of the polarizer and the slow axis of the fixed alignment layer A is 15°, and the angle between the absorption axis of the polarizer and the slow axis of the fixed alignment layer B is 75°. It was transferred (pasted). The liquid crystal alignment solidified layer A (first retardation layer) is attached to a polarizer via an acrylic adhesive layer (thickness: 5 μm, storage modulus at 25° C.: 1.4×10 ⁵ Pa, first adhesive layer). Transferred (pasted) to. The liquid crystal alignment solidified layer B (second retardation layer) was transferred (bonded) to the liquid crystal alignment solidified layer A via an ultraviolet curable adhesive layer (thickness: 1.0 μm, adhesive layer). Further, an acrylic adhesive layer (thickness 20 μm, storage modulus at 25° C. 1.4×10 ⁵ Pa, second adhesive layer) was disposed on the surface of the liquid crystal alignment solidified layer B (second retardation layer). Thereafter, a release liner (a polyethylene terephthalate resin film provided with a release layer) was attached to the surface of the acrylic adhesive layer (second adhesive layer). Finally, a surface protection film comprising a base material (polyethylene terephthalate resin film) and an acrylic adhesive layer laminated on the base material was attached to the protective layer of the polarizing plate.
As described above, a laminated film having the structure of surface protection film/polarizing plate/first adhesive layer/first retardation layer/adhesive layer/second retardation layer/second adhesive layer/release liner was obtained. The laminated film had a rectangular shape when viewed from the lamination direction. The long side dimension of the laminated film was 200 mm, and the short side dimension 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 an end face cutting device. Specifically, the two holding parts held the laminated film between them in the thickness direction with a clamping pressure of 0.17 MPa. Next, the end face of the laminated film was cut using a face mill under the following cutting conditions. In the cutting process, the face milling cutter was moved relative to the end face of the laminated film at the feed rate shown in Table 1. As a result, a cut film (optical laminate) was obtained. Note that 20 samples (cut films) were prepared at each feed rate.
<Cutting conditions>
Number of teeth: 3 Rake angle/mounting angle/relief angle: 20°/10°/6°
Rotation speed: 4500rpm
Maximum cutting amount: 0.8+0.2mm (processed twice)

[evaluation]
As is clear from Table 1, according to the examples of the present invention, the straightness of the end face can be improved by setting the feed rate of the face milling cutter to 800 mm/min or less. It is also seen that lifting of the surface protection film and chipping of the adhesive layer can be suppressed by setting the feed speed of the face milling cutter to 400 mm/min or more.

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

1 Polarizing plate 11 Polarizer 2 First retardation layer 41 First adhesive layer 100 Laminated film

Claims (5)

Including the process of cutting the end face of the film with a face mill,
A method for manufacturing a cut film, wherein the feed rate of the face milling cutter in the cutting step is 800 mm/min or less. The film is a laminated film including: a first film; an adhesive layer laminated on the first film; a second film attached to the first film via the adhesive layer;
The method for producing a cut film according to claim 1, wherein the feed rate of the face milling cutter in the cutting step is 400 mm/min or more. The first film is a polarizer,
The method for producing a cut film according to claim 2, wherein the second film is a retardation layer. The method for producing a cut film according to claim 1, wherein in the cutting step, the end face is cut so that the straightness of the end face is 0.007 mm or less as measured by the following straightness measurement:
Straightness measurement;
Measure the coordinates of the end face at 10 points using a computer numerically controlled image measurement system, calculate an approximate line from the coordinates of the 10 points, and calculate the maximum distance between the approximate line and the end face in a direction orthogonal to the approximate line. The difference between the value and the minimum value is the straightness. A cut film having an end face cut by a face mill, and the straightness of the end face measured by the following straightness measurement is 0.007 mm or less:
Straightness measurement;
Measure the coordinates of the end face at 10 points using a computer numerically controlled image measurement system, calculate an approximate line from the coordinates of the 10 points, and calculate the maximum distance between the approximate line and the end face in a direction orthogonal to the approximate line. The difference between the value and the minimum value is the straightness.

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