Roll and method of manufacturing a powder

Abstract

The present invention provides a roll for pressing a surface of a multilayer film including a substrate layer and a film disposed at the outermost side, on the film side, to form a crack on the film, the roll having a convex portion on the peripheral surface, the convex portion having a height of 1.1T μm or more and 1.5T μm or less, where T represents the thickness (μm) of the film.

Description

Technical Field

[0001] This invention relates to a method for manufacturing rollers and powders. Background Technology

[0002] As pigments for ink, powders consisting of thin film sheets are sometimes used. These thin film sheets are formed from metals, resins, etc.

[0003] To manufacture resin film sheets, there is a known method that involves forming a release layer on a substrate film, forming a resin film on the release layer, forming cracks in the resin film, and then bending the substrate film at an acute angle to peel off the resin film as a film sheet (see Patent Document 1).

[0004] In addition, there are known methods that involve forming a resin film on a substrate film, pressing a member with an uneven shape onto the resin film, forming cracks on the resin film, and spraying fluid onto the cracked resin film to peel off the resin film (see Patent Document 2).

[0005] Existing technical documents

[0006] Patent documents

[0007] Patent Document 1: Japanese Patent Publication No. 07-080248;

[0008] Patent Document 2: International Publication No. 2019 / 189246 (corresponding foreign publication: U.S. Patent Application Publication No. 2021 / 0115336). Summary of the Invention

[0009] The problem the invention aims to solve

[0010] When a component with an uneven shape is pressed onto a film on a substrate film as in the technique described in Patent Document 2, and cracks are formed on the film, sometimes a film sheet adheres to the surface of the component with the uneven shape when the component is separated from the film. When the film sheet adheres to the surface of the component with the uneven shape, the accuracy of crack formation may deteriorate or the component may require frequent cleaning, leading to a decrease in productivity, if the component is used continuously.

[0011] When rollers are used as components with concave and convex shapes, they have the advantage of being able to continuously form cracks on the film. However, this advantage is lost when the film sheet is attached to the roller as described above and requires frequent cleaning.

[0012] Therefore, there is a need for a roller that prevents small pieces of film from adhering when separated from the film after being pressed onto it to form cracks, and a method for manufacturing powder that uses the roller to obtain powder containing small pieces of film.

[0013] Solution for solving the problem

[0014] In order to solve the above problems, the inventors conducted in-depth research and found that the adhesion of the film flakes to the roller is related to the height of the protrusions on the roller.

[0015] This is not intended to limit the invention. The inventors infer that the adhesion of the film sheet to the roller is related to the height of the protrusions on the roller as follows.

[0016] When the height of the protrusions on the roller is too large compared to the thickness of the film causing cracking, the degree of deformation and compression of the film between the protrusions increases when the roller is pressed, causing small film flakes to become trapped between the protrusions and difficult to detach. This can be considered a result of increased adhesion of small film flakes to the roller. On the other hand, it can be considered that when the height of the roller protrusions is the same as the thickness of the film causing cracking, it is difficult to stably generate cracks on the film.

[0017] Based on the above insights, the inventors discovered that by setting the height of the protrusions on the roller within a specified range, it is possible to reduce the adhesion of small film fragments to the roller, thereby completing the present invention.

[0018] That is, the present invention provides the following content.

[0019] [1] A roller for pressing against the surface of a multilayer film comprising a substrate layer and a thin film disposed on the outermost side, thereby forming cracks on the film.

[0020] The roller has a protrusion on its circumferential surface, and the height of the protrusion is more than 1.1Tμm and less than 1.5Tμm, where T represents the thickness (μm) of the film.

[0021] [2] A method for manufacturing powder, comprising the following steps:

[0022] Step (1) involves forming cracks on a multilayer film comprising a substrate layer and a thin film disposed on the outermost side. The cracks are those that, when viewed from the thickness direction of the film, divide the film into small pieces of the same shape, and the cracks extend deeper into the substrate layer than the surface of the thin film side.

[0023] Step (2) involves peeling a small piece of the film from the substrate layer on which the multilayer film with the aforementioned cracks is formed, thereby obtaining powder containing the small piece of the film.

[0024] The above process (1) includes process (1a) of pressing the circumferential surface of the roller onto the thin film side surface of the multilayer film.

[0025] The roller has a protrusion on its circumferential surface, and the height of the protrusion is more than 1.1Tμm and less than 1.5Tμm, where T represents the thickness (μm) of the film.

[0026] [3] In the powder manufacturing method according to [2], the circumferential surface of the roller located between the protrusions is flat.

[0027] [4] The powder manufacturing method according to [2] or [3], wherein the thickness T of the above-mentioned film is 0.1 μm or more and 20 μm or less.

[0028] [5] The method for manufacturing powder according to any one of [2] to [4], wherein in the above-mentioned step (1a), the pressure on the circumferential surface of the roller is 0.5 MPa or more.

[0029] [6] The powder manufacturing method according to any one of [2] to [5], wherein the pressing of the above-mentioned step (1a) is performed in a state in which the multilayer film is supported by a support member with a surface hardness of D40 or higher.

[0030] [7] The method for manufacturing powder according to any one of [2] to [6], wherein the major diameter of the above-mentioned small piece is 150 μm or less.

[0031] Invention Effects

[0032] According to the present invention, a roller is provided that makes it difficult for small pieces of film to adhere when separated from the film after being formed by pressing on the film to create cracks, and a method for manufacturing powder that uses the roller to obtain powder containing small pieces of film. Attached Figure Description

[0033] Figure 1 This is a cross-sectional view showing an example of a multilayer film used in process (1) of one embodiment.

[0034] Figure 2 This is a schematic top view of the thin film side of a multilayer film as seen from the thickness direction of the multilayer film with cracks, according to one embodiment.

[0035] Figure 3 It is shown schematically. Figure 2 Sectional view of section III-III.

[0036] Figure 4 This is a schematic top view of the thin film side of a multilayer film as seen from the thickness direction of the multilayer film with cracks, according to one embodiment.

[0037] Figure 5 It is shown schematically. Figure 4 A cross-sectional view of the VV section.

[0038] Figure 6This is a perspective view schematically illustrating an example of a roller that can be used in a powder manufacturing method according to one embodiment.

[0039] Figure 7 It is shown schematically. Figure 6 A three-dimensional view of the roller shown.

[0040] Figure 8 It is a schematic representation of what will Figure 7 A top view of the roller as it unfolds after being cut along line X1-X1.

[0041] Figure 9 yes Figure 8 A partial sectional view of the Y1-Y1 line.

[0042] Figure 10 This is a perspective view schematically illustrating an example of a roller that can be used in a powder manufacturing method according to one embodiment.

[0043] Figure 11 It is shown schematically. Figure 10 A three-dimensional view of the roller shown.

[0044] Figure 12 It is a schematic representation of what will Figure 11 A top view of the rollers as they are unfolded by being cut along line X2-X2.

[0045] Figure 13 yes Figure 12 A partial sectional view of the Y2-Y2 line. Detailed Implementation

[0046] The present invention will now be described in detail with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be implemented in any way without departing from the scope of the claims and their equivalents. The constituent elements of the embodiments shown below can be appropriately combined. Furthermore, in the figures, the same constituent elements are sometimes labeled with the same reference numerals, and their descriptions are omitted.

[0047] In the following description, "strip" film refers to a film with a length that is 5 times or more than 5 times its width, preferably 10 times or more, specifically a length that allows it to be rolled up for storage or transport. There is no particular upper limit to the length of the film; for example, it can be less than 100,000 times its width.

[0048] In the following description, the term "(meth)acrylic acid" includes "acrylic acid", "methacrylic acid", and combinations thereof.

[0049] In the following description, unless otherwise stated, the orientation of elements as “parallel” and “perpendicular” may include errors within, for example, ±3°, ±2° or ±1°, without impairing the effects of the invention.

[0050] [1. Overview of powder manufacturing methods using rollers]

[0051] In one embodiment of the present invention, a roller is used to form cracks on the film by pressing the roller against the film-side surface of a multilayer film comprising a substrate layer and a film disposed on the outermost side.

[0052] The roller of this embodiment can be used in a powder manufacturing method including the steps (1) and (2) described below. More specifically, it can be used in step (1a) included in step (1) described below.

[0053] In step (1), cracks are formed on a multilayer film comprising a substrate layer and a film disposed on the outermost side. The cracks are cracks that divide the film into small pieces of the same shape when viewed from the thickness direction of the film, and the cracks reach a position deeper than the surface of the substrate layer than the side of the film.

[0054] In step (1a) of step (1), the circumferential surface of the roller is pressed against the thin film side of the multilayer film. The roller has a protrusion on its circumferential surface, the height of which is 1.1Tμm or more and 1.5Tμm or less, where T represents the thickness (μm) of the film.

[0055] In step (2), a small piece of the film is peeled off from the substrate layer on which the multilayer film with the above cracks is formed, and powder containing the small piece of the film is obtained.

[0056] In powder manufacturing processes, by using standardized rollers, the amount of small flakes of film adhering to the rollers can be reduced. As a result, the frequency of roller cleaning can be reduced, increasing powder production efficiency.

[0057] [2. Process (1)]

[0058] In step (1), cracks are formed on a multilayer film comprising a substrate layer and a film disposed on the outermost side. The cracks are cracks that divide the film into small pieces of the same shape when viewed from the thickness direction of the film, and the cracks reach a position deeper than the surface of the substrate layer than the side of the film.

[0059] [2.1. Multilayer film]

[0060] The multilayer film used in step (1) comprises a substrate layer and a thin film. The thin film is disposed on the outermost side of the multilayer film. "Disposed on the outermost side" means that the thin film is disposed on the outermost side of the thickness direction of the multilayer film. Therefore, the surface of the thin film is exposed on one side of the multilayer film. The multilayer film may also have any layer between the thin film and the substrate layer.

[0061] For efficient crack formation, the multilayer film is preferably in strips.

[0062] Figure 1 This is a cross-sectional view illustrating an example of a multilayer film used in step (1) of one embodiment. For example... Figure 1 As shown, the multilayer film 10 includes a substrate layer 12 and a thin film 11 directly disposed on the substrate layer 12. The thin film has a thickness T.

[0063] (Substrate layer)

[0064] For efficient film formation, the substrate layer is preferably elongated.

[0065] Examples of materials forming the substrate layer are not particularly limited, such as resins containing polymers, paper, and metals. From the viewpoint of achieving excellent flexibility and mechanical strength, resins containing polymers are preferred.

[0066] Examples of polymers included in a resin capable of forming a substrate layer include: cellulose-based polymers (e.g., triacetyl cellulose); polymers containing alicyclic structures (e.g., cyclic olefin polymers); polyesters (e.g., polyethylene terephthalate); acrylic polymers (e.g., poly(meth)acrylic acid, poly(meth)acrylate, polyacrylonitrile); and polycarbonate. The resin capable of forming the substrate layer may contain only one polymer or a combination of two or more polymers. Furthermore, the polymer may be a homopolymer or a copolymer. In addition to the polymer, the resin may also contain any additives.

[0067] Examples of polymers containing alicyclic structures include: (1) norbornene polymers, (2) monocyclic cyclic olefin polymers, (3) cyclic conjugated diene polymers, (4) vinyl alicyclic hydrocarbon polymers, and their hydrides. Among these, norbornene polymers and their hydrides are preferred from the viewpoint of transparency and formability.

[0068] Examples of norbornene-based polymers include: ring-opening polymers of monomers having a norbornene structure and their hydrides; addition polymers of monomers having a norbornene structure and their hydrides. Furthermore, examples of ring-opening polymers of monomers having a norbornene structure include: ring-opening homopolymers of a single monomer having a norbornene structure; ring-opening copolymers of two or more monomers having a norbornene structure; and ring-opening copolymers of a monomer having a norbornene structure and any monomer capable of copolymerizing therewith. Moreover, examples of addition polymers of monomers having a norbornene structure include: addition homopolymers of a single monomer having a norbornene structure; addition copolymers of two or more monomers having a norbornene structure; and addition copolymers of a monomer having a norbornene structure and any monomer capable of copolymerizing therewith. Examples of such polymers include those disclosed in Japanese Patent Application Publication No. 2002-321302, etc.

[0069] Specific examples of preferred norbornene polymers and their hydrides include: "ZEONOR" manufactured by Zeon Corporation of Japan; "ARTON" manufactured by JSR Corporation; and "TOPAS" manufactured by TOPAS ADVANCED POLYMERS.

[0070] The thickness of the substrate layer is preferably 12 μm or more, more preferably 25 μm or more, even more preferably 50 μm or more, preferably 250 μm or less, more preferably 200 μm or less, and even more preferably 188 μm or less. By having a substrate layer thickness above the aforementioned lower limit, the mechanical strength of the substrate layer is improved. By having a substrate layer thickness below the aforementioned upper limit, the flexibility of the substrate layer is improved, making manufacturing easier.

[0071] The substrate layer can have a single-layer structure or a multi-layer structure.

[0072] In the case where the substrate layer has a multilayer structure, each layer contained in the substrate layer preferably has a peel strength that prevents it from peeling off from each other in steps (1) and (2).

[0073] The substrate layer preferably has a single-layer structure.

[0074] The substrate layer can also undergo treatments such as friction treatment and corona treatment on its surface.

[0075] The substrate layer can be an unstretched layer or a stretched layer.

[0076] Multilayer films can consist of only a substrate layer and a thin film, or they can have any additional layers besides the substrate layer and the thin film. For example, when using a liquid crystal composition as the composition for forming the thin film, from the viewpoint of ensuring good alignment of the liquid crystal composition, the multilayer film can have an alignment film between the substrate layer and the thin film. The alignment film can be formed from a resin containing polymers such as polyimide, polyvinyl alcohol, polyester, polyarylate, polyamide-imide, polyether-imide, and polyamide. Furthermore, these polymers can be used alone or in combination of two or more in any ratio. The alignment film can be manufactured by coating a solution containing the above-mentioned polymers, drying, and subjecting it to a friction treatment.

[0077] (film)

[0078] Thin films can be any structure, including single-layer and multilayer structures. Furthermore, thin films can be either conductors or dielectrics. Moreover, thin films can be either inorganic or organic films. Examples of thin films include: films made of metals such as aluminum and silver; dielectric multilayer films formed from dielectrics such as titanium oxide, silicon oxide, niobium oxide, tantalum oxide, and magnesium fluoride; and resin films.

[0079] Examples of resin materials used to form resin films include: photocurable liquid crystal compositions, acrylic resins, polystyrene, polyesters, polyamides, polyvinyl chloride, polyvinyl acetate, cellulose polymers (e.g., triacetyl cellulose), polycarbonates, polyurethanes, polyolefins, alicyclic polymers, epoxy resins, melamine resins, phenolic resins, and combinations thereof. The polymers that the resin material can contain can be homopolymers or copolymers. In addition to polymers, the resin material can also contain any additives such as curing agents and antioxidants.

[0080] The thickness T of the film can be appropriately set according to the material of the film and the intended use of the powder. From the viewpoint of ensuring the reflectivity of the film, it is preferably 0.1 μm or more, more preferably 0.5 μm or more, even more preferably 1 μm or more, preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less. By keeping the thickness of the film below the above-mentioned upper limit, the obtained powder can be appropriately used for inks corresponding to printing layers of various thicknesses.

[0081] When the film thickness T is small, small pieces of film tend to adhere to the roller. However, by using the roller of this embodiment, even when the film thickness is small (for example, the film thickness T is preferably 20 μm or less, more preferably 15 μm or less, and even more preferably 10 μm or less), the adhesion of small pieces of film to the roller can be reduced.

[0082] As a thin film, for example, a cured film formed by using a photocurable liquid crystal composition as a resin-containing composition and curing it can be used. That is, as the resin forming the thin film, a cured product of a photocurable liquid crystal composition can be used, for example. Here, for convenience, the material referred to as a "liquid crystal composition" includes not only mixtures of two or more substances, but also materials composed of a single substance.

[0083] Furthermore, cholesteric resin layers, for example, can be used as thin films. A cholesteric resin layer refers to a resin layer exhibiting cholesteric regularity. The cholesteric regularity of a cholesteric resin layer means that, on one plane, the molecular axes are aligned in a certain direction; in the next plane that overlaps with it, the direction of the molecular axes shifts at a small angle; in the next plane after that, a further angular shift occurs, and so on, as it progresses through the overlapping planes, the angle of the molecular axes in these planes gradually shifts (twistrate). That is, when the molecules within the layer exhibit cholesteric regularity, the molecules are arranged within the resin layer in a manner that forms multiple molecular layers. In a certain layer A among these multiple molecular layers, the molecules are aligned with their molecular axes in a certain direction; in the adjacent layer B, the molecules are aligned in a direction that is angularly offset from the direction of layer A; and in the further adjacent layer C, the molecules are aligned in a direction that is angularly offset from the direction of layer B. In this way, the angle of the molecular axes shifts continuously in multiple molecular layers, forming a molecularly twisted structure. Structures in which the direction of the molecular axis is gradually twisted are optically known as chiral structures.

[0084] Cholesteric resin layers typically possess circular polarization separation capabilities. That is, they transmit one of the circularly polarized light beams (either right-handed or left-handed) and reflect part or all of the other circularly polarized light. Furthermore, the reflection of cholesteric resin layers occurs while preserving the chirality of the circularly polarized light.

[0085] When using the cholesteric resin layer as described above as a thin film, the manufacturing method of this embodiment can produce a powder with a large proportion of thin film sheets of a certain shape, which are composed of small pieces of resin film that effectively utilize the circular polarization light separation function.

[0086] Thin films can be formed by any method depending on the material they are made of. For example, thin films can be formed by vapor deposition, sputtering, coating, etc. Among these, examples of coating methods include: mold coating, curtain coating, extrusion coating, roller coating, spin coating, dip coating, bar coating, spray coating, sliding coating, printing coating, gravure coating, and slot coating.

[0087] [2.2. Formation of cracks]

[0088] (Cracked)

[0089] The cracks formed in step (1), when viewed from the thickness direction of the film, divide the film contained in the multilayer film into small pieces of the same shape. Furthermore, the cracks can be formed at a location deeper in the substrate layer than the surface of the film side. Alternatively, the cracks can be formed on the entire surface of the multilayer film at a location deeper in the substrate layer than the surface of the film side.

[0090] The shape of the small patch observed in the thickness direction of the film is not particularly limited, and examples include: triangles, quadrilaterals, hexagons and other polygons; cross shapes; circles, etc., with triangles, quadrilaterals or hexagons being preferred.

[0091] From the viewpoint of suppressing ink clogging of the printing plate, the major axis of the small piece observed in the thickness direction of the film is preferably 250 μm or less, more preferably 200 μm or less, even more preferably 175 μm or less, and even more preferably 150 μm or less. From the viewpoint of improving the visibility of the printed layer formed by the ink, it is generally greater than 0 μm, and preferably 10 μm or more. Here, the major axis refers to the longest distance between parallel lines when several parallel lines connect to the outline of the small piece.

[0092] The following describes an example of cracks formed in process (1).

[0093] Figure 2 This is a schematic top view of the thin film side of a multilayer film as seen from the thickness direction of the multilayer film with cracks, according to one embodiment. Figure 3 It is shown schematically. Figure 2 Sectional view of section III-III.

[0094] like Figure 2 As shown, a lattice-like crack 100C is formed in the multilayer film 100. The crack 100C consists of multiple straight cracks 100C1 extending downward to the right at an angle θ1 relative to the width direction WD of the multilayer film 100, and multiple straight cracks 100C2 extending upward to the right at an angle θ2 relative to the width direction WD of the multilayer film 100. Wherein, when relative to... Figure 2 When the width direction WD of the multilayer film 100 is 45° and the angle in the clockwise direction is positive and the angle in the counterclockwise direction is negative, θ1 is 45° and θ2 is -45°.

[0095] In this embodiment, the spacing P11 between adjacent cracks 100C1 is approximately the same as the spacing P12 between adjacent cracks 100C2. "Approximately the same" means that P12 is more than 90% and less than 110% of P11. The lattice-like crack 100C having multiple cracks 100C1 and multiple cracks 100C2 divides the outermost film of the multilayer film 100 into multiple approximately square pieces 101. Each piece 101 has sides of length corresponding to the spacings P11 and P12; in this embodiment, one side of each piece 101 has a length of P11.

[0096] like Figure 3 As shown, the multilayer film 100 has a substrate layer 120 and a thin film 110 formed directly on the substrate layer 120. The depth 100Cd of the crack 100C is the distance from the surface 110U on the thin film 110 side of the multilayer film 100 to the tip 100Ct of the crack 100C. The depth 100Cd of the crack 100C is greater than the thickness 110T of the thin film 110. Therefore, the tip 100Ct of the crack 100C reaches a position in the substrate layer 120 that is deeper than the surface 120U on the thin film 110 side.

[0097] Figure 4 This is a schematic top view of the thin film side of the multilayer film as viewed from the thickness direction of the multilayer film with cracks, according to another embodiment. Figure 5 It is shown schematically. Figure 4 A cross-sectional view of the VV section.

[0098] like Figure 4 As shown, honeycomb-shaped cracks 200C are formed in the multilayer film 200. The honeycomb-shaped cracks 200C divide the outermost thin film of the multilayer film 200 into a plurality of approximately hexagonal small pieces 201.

[0099] like Figure 5 As shown, the multilayer film 200 has a substrate layer 220 and a thin film 210 formed directly on the substrate layer 220. In this embodiment, the tip 200Ct of the crack 200C also reaches a deeper position on the substrate layer 220 than the surface 220U on the side of the thin film 210.

[0100] In another embodiment, cracks that appear as continuous triangular patterns when viewed from the thickness direction of the multilayer film can also be formed on the multilayer film.

[0101] (Process (1a))

[0102] In step (1a), the circumferential surface of the roller is pressed against the thin film side of the multilayer film. This allows cracks to be formed on the thin film contained within the multilayer film.

[0103] Here, the roller has a protrusion on its circumferential surface. The height of the protrusion is typically 1.1Tμm or more, preferably 1.15Tμm or more, more preferably 1.20Tμm or more, typically 1.5Tμm or less, preferably 1.45Tμm or less, more preferably 1.40Tμm or less, where T represents the thickness of the film (μm). In another embodiment, the height of the protrusion of the roller is preferably 1.1μm or more, more preferably 1.5μm or more, more preferably 1.6μm or more, more preferably 2.0μm or more, more preferably 3.0μm or more, preferably 21.5μm or less, more preferably 21.0μm or less, more preferably 16.5μm or less, more preferably 16.0μm or less, more preferably 15.0μm or less, more preferably 11.5μm or less, more preferably 11.0μm or less, more preferably 10.0μm or less.

[0104] The height of the convex part of the roller refers to the height of the convex part based on the deepest position on the circumference of the roller (the position closest to the roller shaft).

[0105] In step (1a), a roller with protrusions on its peripheral surface corresponding to the shape of the cracks observed from the thickness direction of the multilayer film can be used. For example, if the shape of the cracks observed from the thickness direction of the multilayer film is lattice-like, a roller with lattice-shaped protrusions on its peripheral surface can be used. Furthermore, if the shape of the cracks observed from the thickness direction of the multilayer film is honeycomb-like, a roller with honeycomb-shaped protrusions on its peripheral surface can be used.

[0106] Furthermore, process (1a) can be repeated multiple times. For example, a first process (1a) using a roller with a protrusion on its peripheral surface corresponding to a portion of the crack can be performed, and a second process (1a) using a roller with a protrusion on its peripheral surface corresponding to another portion of the crack can be performed. For example, when the crack is grid-like and the film is divided into squares when viewed from its thickness direction, the crack can be formed by pressing the first roller and the second roller described below onto the multilayer film, wherein the first roller has a protrusion on its peripheral surface corresponding to a crack in one direction constituting the crack, and the second roller has a protrusion on its peripheral surface corresponding to a crack in another direction constituting the crack.

[0107] The roller can be made of a material that possesses strength sufficient to withstand pressure without breaking and can form an uneven texture. Examples of such materials include carbon steel and stainless steel. Furthermore, to improve corrosion resistance, strength, thermal conductivity, etc., the roller surface can have one or more multi-layered films. Such films are not particularly limited and can include, for example, electroplated films of nickel, nickel-phosphorus, silicon, copper, etc.; films formed by ceramic spraying, etc. Heating units, such as heaters, heating media, dielectric heating, induction heating, etc., can also be installed on the roller; static eliminators to prevent static electricity; grounding wires, etc.

[0108] Rollers can be manufactured using any method currently known. For example, by cutting cylindrical metal rollers or other components using cutting tools such as diamond cutters, or by processing them using laser processing equipment, rollers with desired concave and convex shapes can be formed.

[0109] The pressure applied when the roller presses against the thin film side of the multilayer film is preferably 0.5 MPa or more, more preferably 1 MPa or more, even more preferably 5 MPa or more, preferably 100 MPa or less, and more preferably 75 MPa or less. By keeping the pressure above the lower limit, sufficiently deep cracks can be formed on the multilayer film; by keeping the pressure below the upper limit, damage to the multilayer film can be suppressed. When a roller with one or more irregular shapes is pressed repeatedly on the multilayer film to form cracks, the repeated pressings can be the same or different. It is preferable that the repeated pressings are performed at the same pressure.

[0110] Preferably, the multilayer film is sandwiched between the support member and the roller with the protrusion while the multilayer film is supported by the support member and pressed against the roller with the protrusion.

[0111] The support member typically has a support surface that supports the side opposite to the thin film side of the multilayer film. The hardness of the support surface supporting the multilayer film is preferably D40 or higher, more preferably D60 or higher, even more preferably D70 or higher, preferably D99 or lower, more preferably D97 or lower, and even more preferably D95 or lower. Herein, hardness is a value measured using a hardness tester (Type D) according to JIS K-6253. By setting the hardness of the support surface of the support member within the above range, it is easy to form cracks of appropriate depth on the multilayer film. As the support member, a material with strength that will not cause damage even when the multilayer film is pressed by a roller can be used. Examples of materials for the surface of the support member include rubber and resin.

[0112] The shape of the support member can be arbitrary (e.g., roller-shaped, flat-shaped) depending on, for example, the method of transporting the multilayer film or the method of pressing a member with concave and convex shapes onto the multilayer film. Since using a long strip of multilayer film allows for continuous cracking on the multilayer film, the support member is preferably roller-shaped.

[0113] Hereinafter, an example of a roller with a protrusion and the process (1) of using the roller will be described.

[0114] Figure 6 This is a perspective view schematically showing an example of a roller that can be used in the powder manufacturing method of this embodiment. Figure 7 It is shown schematically. Figure 6 A three-dimensional view of the roller shown. Figure 8 It is a schematic representation of what will Figure 7 A top view of the components unfolded by cutting along line X1-X1. Figure 9 yes Figure 8 A partial sectional view of the Y1-Y1 line. Figure 10 This is a perspective view schematically showing an example of a roller that can be used in the powder manufacturing method of this embodiment. Figure 11 It is shown schematically. Figure 10 A three-dimensional view of the roller shown. Figure 12 It is a schematic representation of what will Figure 11 A top view of the components unfolded by cutting along the X2-X2 line. Figure 13 yes Figure 12 A partial sectional view of the Y2-Y2 line.

[0115] like Figure 6 As shown, roller 1110 is arranged in contact with the surface of the multilayer film 10 on the thin film 11 side, pressing the multilayer film 10. Furthermore, as... Figure 10 As shown, roller 1115 is arranged in contact with the surface of the multilayer film 10 on the thin film 11 side, and presses the multilayer film 10. The order in which roller 1110 presses the multilayer film 10 and roller 1115 press the multilayer film 10 is not particularly limited. For example, roller 1110 can be used to press the multilayer film 10, followed by roller 1115; or roller 1115 can be used to press the multilayer film 10, followed by roller 1110.

[0116] like Figure 6 As shown, the circumferential surface of roller 1110 (the surface in contact with the multilayer film 10) has a protrusion. For example... Figure 10 As shown, the circumferential surface of roller 1115 also has protrusions. Rollers 1110 and 1115 are as follows... Figure 6 and Figure 10 As shown, it is cylindrical and can rotate and move on the multilayer film 10.

[0117] The support member 1120 disposed on the side of the substrate layer 12 of the multilayer film 10 is a member that, together with the roller 1110, clamps and presses the multilayer film 10.

[0118] The support member 1125 disposed on the side of the substrate layer 12 of the multilayer film 10 is a member that, together with the roller 1115, clamps and presses the multilayer film 10. The support member 1120 and the support member 1125 are each cylindrical and can rotate and move under the multilayer film 10.

[0119] In the multilayer film 10, the side that contacts rollers 1110 and 1115 (the upper surface in the figure) is the surface on which the thin film 11 is formed. When the multilayer film 10 is sandwiched between roller 1110 and support member 1120, the protrusion 1110T of roller 1110 contacts the thin film 11. By pressing while the multilayer film 10 is sandwiched between roller 1110 and support member 1120, the protrusion 1110T of roller 1110 penetrates into the interior of the thin film 11 and substrate layer 12, and cracks 100C1 constituting cracks 100C can be formed. Furthermore, when the multilayer film 10 is sandwiched between roller 1115 and support member 1125, the protrusion 1115T of roller 1115 contacts the thin film 11. By pressing the multilayer film 10 while it is sandwiched between the roller 1115 and the support member 1125, the protrusion 1115T of the roller 1115 penetrates into the interior of the film 11 and the substrate layer 12, forming cracks 100C2 that constitute cracks 100C. In this way, a multilayer film 10 with cracks 100C formed can be obtained (see reference). Figure 2 and Figure 3 ).

[0120] A protrusion is formed on the circumferential surface of roller 1110, thereby creating a concave-convex shape. For example... Figure 8 As shown, the convex-concave shape is a shape in which a convex portion 1110T and a concave portion 1110D, extending in a direction inclined at an angle θx relative to the direction represented by L1, are alternately and repeatedly formed in a direction perpendicular to the forming direction of the convex portion 1110T. θx is not particularly limited and can be, for example, 45°. Figure 8 As shown, the convex and concave shapes of roller 1110, viewed from the paper surface, are arranged in a straight line pointing downwards to the right. The distance between two adjacent convex parts 1110T ( Figure 9 The distance Q1 between the convex portions 1110T1 and 1110T2 shown can be appropriately set. Figure 7 and Figure 8 In the middle, ends 1111 and 1112 are the ends of roller 1110.

[0121] like Figure 9 As shown in the cross-sectional view, the convex portion 1110T can be a mountain shape with an acute-angled apex 1110t. Figure 9In this context, θ11 is the angle of the vertex of the protrusion. θ11 is preferably a small angle, such as 10° or more, 20° or more, or 30° or more, and can be, for example, 90° or less, 80° or less, 70° or less, or 60° or less. The vertex shape of the protrusion 1110T can be a rounded or chamfered shape as long as it can form a crack on the film and substrate layer.

[0122] like Figure 9 As shown, the height H1 of protrusions 1110T1 and 1110T2 refers to the height of the protrusion relative to the deepest position P (the position closest to the roller shaft) on the circumferential surface 1110S of roller 1110. Height H1 is typically above 1.1T μm and below 1.5T μm. Here, T represents the thickness (μm) of film 11.

[0123] like Figure 9 As shown, the circumferential surface between adjacent protrusions 1110T1 and 1110T2 is flat. Therefore, when the roller 1110 is pressed against the film 11 side of the multilayer film 10, protrusions 1110T1 and 1110T2 are prevented from being pressed too deeply into the multilayer film 10 compared to their height. As a result, the adhesion of film flakes to the roller 1110 can be further reduced.

[0124] A protrusion is formed on the circumferential surface of roller 1115, thereby creating a concave-convex shape. For example... Figure 12 As shown, the convex-concave shape is a shape in which a convex portion 1115T and a concave portion 1115D, extending in a direction inclined at an angle θy relative to the direction represented by L2, are alternately and repeatedly formed in a direction perpendicular to the forming direction of the convex portion 1115T. θy is not particularly limited and can be, for example, 45°. Figure 12 As shown, the convex and concave shapes of roller 1115, viewed from the paper surface, are arranged in a straight line pointing upwards to the right. The distance between two adjacent convex parts 1115T ( Figure 13 The distance Q2 between the convex portions 1115T1 and 1115T2 shown can be appropriately set. Figure 11 and Figure 12 In the middle, ends 1116 and 1117 are the ends of roller 1115.

[0125] like Figure 13 As shown in the cross-sectional view, the convex portion 1115T can be a mountain shape with an acute-angled apex 1115t. Figure 13 In this context, θ12 is the angle of the vertex of the protrusion. θ12 is preferably a small angle, such as 10° or more, 20° or more, or 30° or more, and can be, for example, 90° or less, 80° or less, 70° or less, or 60° or less. The vertex shape of the protrusion 1115T can be a rounded or chamfered shape as long as it can form a crack on the film and substrate layer.

[0126] like Figure 13 As shown, the height H2 of protrusions 1115T1 and 1115T2 refers to the height of the protrusion relative to the deepest position P (the position closest to the roller shaft) on the circumferential surface 1115S of roller 1115. Height H2 is typically above 1.1Tμm and below 1.5Tμm. Here, T represents the thickness (μm) of film 11.

[0127] like Figure 13 As shown, the circumferential surface between adjacent protrusions 1115T1 and 1115T2 is flat, just like the roller 1110. Therefore, for the same reasons explained for roller 1110, the adhesion of small film flakes to roller 1115 can be further reduced.

[0128] By performing process (1), cracks can be formed on the multilayer film (e.g., as shown in the image). Figure 3 and Figure 5 As shown, cracks 100C or 200C are formed on the multilayer film 10. The multilayer film with cracks (e.g., multilayer film 100, 200) is supplied to process (2).

[0129] The shape of the cracks can reflect the shape of the convex parts of the roller. For example, when unfolding a shape like... Figure 8 The roller 1110 shown is Figure 8 When the L1 direction is arranged parallel to the length direction of the multilayer film and pressed, cracks can be formed in a direction inclined relative to the length direction of the multilayer film 10. Then, when the unfolded shape is as follows... Figure 12 The roller 1115 shown is Figure 12 When the L2 direction is arranged parallel to the length direction of the multilayer film and pressed, it can form a shape like... Figure 2 The grid-like cracks shown are at 100°C. In Figure 2 In the middle, the straight crack 100C1 pointing to the lower right reflects the shape of the protrusion of roller 1110, and the straight crack 100C2 pointing to the upper right reflects the shape of the protrusion of roller 1115.

[0130] As described above, the height of the protrusions on the circumferential surfaces of the rollers 1110 and 1115 used in the manufacturing method of this embodiment is typically 1.1Tμm or more and 1.5Tμm or less. This reduces the adhesion of small film flakes to the rollers.

[0131] When the height of the roller's protrusions is too large compared to the thickness of the film causing cracking, the degree of deformation and compression of the film between the protrusions increases when the roller is pressed, resulting in small pieces of film becoming trapped between the protrusions and difficult to detach. Consequently, there is an increase in the adhesion of small film pieces to the roller. On the other hand, when the height of the roller's protrusions is the same as the thickness of the film causing cracking, it becomes difficult to stably generate cracks on the film.

[0132] Furthermore, as described above, the circumferential surfaces of rollers 1110 and 1115 located between adjacent protrusions are flat. This prevents the protrusions from being pressed excessively deep into the multilayer film beyond their height. As a result, the adhesion of film flakes to the rollers can be further reduced.

[0133] Therefore, the rollers used in the manufacturing method of this embodiment do not require frequent cleaning, and powder can be manufactured with excellent productivity.

[0134] The adhesion of the film sheet to the roller can be evaluated by either of the following methods (1) and (2).

[0135] Method (1)

[0136] Use a microscope to observe the surface of the center of the roller.

[0137] Within a 1 mm square area, the area of ​​the film present on the peripheral surface (recess) excluding the convex part of the roller is measured.

[0138] The smaller the area of ​​the film being measured, the less the film flakes adhere to the roller.

[0139] Method (2)

[0140] Use a microscope to observe the surface of the center of the roller.

[0141] Within a 1mm square area, count the number of small film flakes present on the peripheral surface (recess) excluding the protrusions of the roller.

[0142] The fewer the number of film fragments counted, the less the film fragments adhere to the roller.

[0143] [3. Process (2)]

[0144] In step (2), a small piece of the above-mentioned film is peeled off from the substrate layer of the multilayer film with cracks to obtain powder containing the small piece of the above-mentioned film.

[0145] There is no particular limitation on the method for peeling small pieces of film from the substrate layer. Examples include: (1) peeling small pieces by sliding a cracked multilayer film on a squeegee; (2) peeling small pieces by spraying a fluid such as water or air onto a cracked multilayer film; (3) peeling small pieces of film from the substrate layer by immersing a cracked multilayer film in a solvent (e.g., water) that is difficult to dissolve the film (e.g., a cholesteric resin layer) but can dissolve the substrate layer or a layer between the film and the substrate layer (e.g., an orientation film formed of polyvinyl alcohol); (4) peeling small pieces of film from the substrate layer by attaching the film side of the cracked multilayer film to a transfer substrate film using a water-soluble adhesive, and then peeling the substrate layer from the multilayer film; and combinations of these methods.

[0146] In the method described in (4) above, a laminate with a layer structure of (transfer substrate film) / (water-soluble adhesive layer) / (cracked film) can usually be obtained. By immersing this laminate in water at an appropriate temperature, the water-soluble adhesive layer is removed from the laminate, thereby obtaining powder containing small flakes of film.

[0147] When the multilayer film with cracks is in the form of long strips, powder can be manufactured efficiently by continuously performing the above-mentioned peeling process.

[0148] For example, step (2) may also include step (2a) of spraying fluid into a multilayer film with cracks.

[0149] In step (2a), fluid is sprayed onto the cracked side (i.e., the film side) of the multilayer film with cracks. A known fluid ejection device can be used as the spraying device. The pressure of the fluid ejected from the fluid ejection device can be appropriately adjusted according to the fluid density, the peel strength between the substrate layer and the film, etc. The ejection pressure is not particularly limited, but is preferably 5 MPa or more, more preferably 10 MPa or more, more preferably 50 MPa or less, and more preferably 35 MPa or less.

[0150] Step (2) may also include step (2b) of sieving the small pieces after peeling off the above-mentioned film.

[0151] For example, after the step (2a) of spraying fluid into a multilayer membrane with cracks, small pieces peeled off from the substrate layer can be passed through a filter with a specified pore size.

[0152] In addition, step (2) may also include step (2c) of recycling the small pieces after peeling off the above-mentioned film.

[0153] For example, after the step (2a) of spraying fluid into a multilayer film with cracks, small pieces peeled off from the substrate layer can be introduced into a recovery path along with the fluid, and the small pieces can be recovered by a recoverer to obtain powder as an aggregate of small pieces. As the recoverer, for example, a cyclone separator and various filters can be used.

[0154] [4. Properties of Powders]

[0155] In the powder obtained by the manufacturing method of this embodiment, a large proportion of thin film sheets with a certain shape along the cracks are present. This proportion can be evaluated by, for example, the following method.

[0156] A 10% by weight aqueous dispersion of the powder was prepared. This aqueous dispersion was dropped onto a microscope slide, and the water was evaporated, causing the powder (film sheet) to adhere to the slide. The area where the film sheet adhered was observed under a microscope. The number (A) of film sheets of a specific shape and the number (B) of amorphous film sheets were counted within a 1 mm square area. The percentage X of the number (B) relative to the number (A) was calculated using the following formula: X = B / A × 100 (%)

[0157] The smaller the percentage X, the higher the proportion of films with a certain shape along the crack.

[0158] The percentage of powder X is preferably 5% or less, more preferably 4% or less, even more preferably 3% or less, preferably 0%, and may also be 0% or more or 1% or more.

[0159] [5. Uses of Powders]

[0160] In the powder manufactured by the method of this embodiment, a large proportion of thin films with a certain shape along the cracks are present. Therefore, ink containing powder can produce printed materials with good texture. Furthermore, the authenticity of printed materials using ink containing powder can be easily determined. Therefore, powder can be appropriately used as an ink material.

[0161] Example

[0162] The following embodiments illustrate the present invention in detail. However, the present invention is not limited to the embodiments shown below, and can be implemented in any way without departing from the scope of the claims and their equivalents.

[0163] In the following descriptions, unless otherwise stated, "%" and "parts" refer to quantities based on weight. Furthermore, unless otherwise stated, the operations described below are performed at room temperature (20℃±15℃) and normal pressure (1 atm).

[0164] [evaluate]

[0165] (Peeling sheet attachment)

[0166] The surface of the central portion of the roller used for the second crack induction in each example was observed under a microscope. The number of peeling flakes present in the concave-convex recesses within a 1 mm square area was counted. The fewer the number of peeling flakes, the less adhesion of the peeling flakes (small pieces) to the roller, and the more efficient the continuous crack induction. Peeling flake adhesion was evaluated according to the following criteria.

[0167] "Good": Number of peeling pieces < 5

[0168] "Defective": Number of peeling pieces ≥ 5

[0169] [Example 1]

[0170] (1-1. Preparation of photocurable liquid crystal compositions)

[0171] A photocurable liquid crystal composition was prepared by mixing 18.1 parts of a photopolymerizable liquid crystal compound "Paliocolor LC242" manufactured by BASF, 1.3 parts of "LC756" manufactured by BASF as a chiral agent, 0.6 parts of "Irgacure OXEO2" manufactured by CIBA JAPAN as a photopolymerization initiator, 0.02 parts of "FTERGENT 209F" manufactured by NEOS as a surfactant, and 80 parts of cyclopentanone.

[0172] (1-2. Manufacturing of long strip multilayer films)

[0173] A long strip of cyclic olefin polymer (COP) film (Zeon Corporation, Japan, "ZF16-100"; 100 μm thick) was prepared as the substrate film. This substrate film was mounted on the delivery section of a film conveying device, and the following operations were performed while conveying the substrate film along its length. First, a rubbing treatment was performed in the length direction parallel to the conveying direction. Next, the liquid crystal composition prepared in (1-1) was applied to the rubbed surface using a die-coating machine. Thus, an uncured liquid crystal composition film was formed on one side of the substrate film.

[0174] The resulting liquid crystal composition film was subjected to an alignment treatment at 100°C for 5 minutes, and then irradiated with 800 mJ / cm² under a nitrogen atmosphere. 2 Ultraviolet light is used to completely cure the liquid crystal composition film. This results in a multilayer film with a resin film thickness of 3.5 μm on one side of a strip of substrate film. The multilayer film has a layer structure of (substrate film as substrate layer) / (resin film). The resin film functions as a cholesteric resin layer.

[0175] (1-3. Manufacturing of components (rollers) with concave and convex shapes)

[0176] Prepare metal rollers made of stainless steel with electroless nickel plating (NiP plating) applied to their surfaces. Cut the surface of the plated rollers with a diamond cutter (to flatten the top with a 50° apex angle and to create a flat section with a cross-sectional length of 46 μm) to obtain rollers A and B with multiple protrusions.

[0177] In roll A, a plurality of protrusions are formed in such a manner as follows: the protrusions extend at an angle of 45° to the upper right relative to a straight line on the roll circumferential surface parallel to the roll axis, and the spacing between the protrusions is 50 μm, and further, on a cross section perpendicular to the direction of extension of the protrusions, the angle of the apex of the protrusions is 50°.

[0178] In roll B, a plurality of protrusions are formed in such a manner as follows: the protrusions extend at an angle of 45° to the upper left relative to a straight line on the roll circumferential surface parallel to the roll axis, and the spacing between the protrusions is 50 μm, and further, on a cross section perpendicular to the direction of extension of the protrusions, the angle of the apex of the protrusions is 50°.

[0179] The depth of the cut portion (height of the protrusion) of each roller, measured using a laser microscope, was 4.3 μm.

[0180] (1-4. Process (1): Cracking formation process)

[0181] On the multilayer film that can be manufactured in (1-2), roller A manufactured in (1-3) is pressed (pressure 10 MPa) from the resin film side, followed by roller B (pressure 10 MPa), forming cracks on the multilayer film. At this time, the side of the multilayer film opposite to the resin film (substrate film side, support roller side) is supported by a support roller. The support roller is a roller with a surface hardness of D70. The hardness is the value measured using a hardness tester (type D) according to JIS K-6253. The same applies below. Thus, the resin film of the multilayer film is divided into small square pieces (long axis 70 μm) with a side length of 50 μm when viewed from the thickness direction of the resin film.

[0182] For roller B after the crack formation process, the adhesion status of the release liner is evaluated using the method described above. The predicted result is low release liner adhesion.

[0183] (1-5. Process (2): Powder manufacturing process)

[0184] Next, water is sprayed from one side of the resin film at a pressure of 60 MPa onto the cracked multilayer film to peel off small pieces of the resin film from the substrate film.

[0185] Next, the small pieces of the peeled resin film are passed through a sieve with a nominal pore size of 53 μm, and the pieces that pass through the sieve are recovered using a filter recovery device (made by 3M, all-polypropylene filter) to obtain powder containing small pieces of resin film.

[0186] [Example 2]

[0187] (2-1~2-2)

[0188] A strip of triacetyl cellulose membrane (manufactured by Nicaminol Corporation, "KC6UY"; thickness 60 μm) was used as the substrate membrane. Except as described above, the process was the same as in (1-1) to (1-2) of Example 1 to manufacture a multilayer membrane.

[0189] (2-3. Manufacturing of components (rollers) with concave and convex shapes)

[0190] Prepare a metal roller identical to (1-3) of Example 1, and cut the surface of the coated roller with a diamond cutter (to flatten the top end with a 50° apex angle and to provide a flat portion with a cross section length of 96 μm) to obtain a roller C with multiple protrusions.

[0191] In roll C, a plurality of protrusions are formed in such a manner as follows: the protrusions extend at an angle of 45° to the upper left relative to a straight line on the roll circumferential surface parallel to the roll axis, and the distance between the protrusions is 100 μm.

[0192] The depth of the cut portion (height of the protrusion) of each roller, measured using a laser microscope, was 4.3 μm.

[0193] (2-4. Process (1): Cracking formation process)

[0194] Using roller C instead of roller B, the same procedure as in (1-4) of Example 1 is followed to form cracks on the multilayer film. As a result, the resin film of the multilayer film is divided into small rectangular pieces (112 μm long axis) with a thickness of 50 μm × 100 μm when viewed from the thickness direction of the resin film.

[0195] For roller C after the crack formation process, the adhesion of the release liner is evaluated using the method described above. It is expected that the adhesion of the release liner will be minimal.

[0196] (2-5. Process (2): Powder manufacturing process)

[0197] The aperture of the sieve through which the peeled resin film flakes passed was changed from a nominal aperture of 53 μm to a nominal aperture of 106 μm. Except for the above, the same procedure as in Example 1 (1-5) was performed to obtain the powder.

[0198] [Example 3]

[0199] (3-1~3-2)

[0200] A 12 μm thick polyethylene terephthalate (PET) film (manufactured by Toray Advanced Film, "VMPET1519") coated with aluminum was prepared as a multilayer film. The multilayer film has a layer structure of (aluminum film as thin film) / (PET film as substrate layer).

[0201] (3-3. Manufacturing of components (rollers) with concave and convex shapes)

[0202] Prepare a metal roller identical to (1-3) in Example 1. Use an ultrashort pulse laser to form pits (denting) on ​​the surface of the coated roller to obtain roller D.

[0203] In roller D, a continuous hexagonal protrusion is formed with a major diameter of 50 μm, a side length of 25 μm, and a depth of the concave portion (height of the convex portion) of 14 μm.

[0204] (3-4. Process (1): Cracking formation process)

[0205] • Using roller D instead of roller A, and without using roller B to press the multilayer film, the operation is the same as in (1-4) of Example 1, to form cracks on the multilayer film. Thus, the aluminum film of the multilayer film is divided into small hexagonal pieces with a major diameter of 50 μm and a side length of 25 μm when viewed from the thickness direction of the film.

[0206] For roller D after the crack formation process, the adhesion status of the release liner is evaluated using the method described above. It is expected that the adhesion of the release liner will be minimal.

[0207] (3-5. Process (2): Powder manufacturing process)

[0208] The same procedure as in Example 1 (1-5) was performed to obtain powder.

[0209] [Comparative Example 1]

[0210] (4-1. Manufacturing of components (rollers) with concave and convex shapes)

[0211] Prepare metal rollers made of stainless steel with electroless nickel plating (NiP plating) applied to their surfaces. Cut the surface of the plated rollers with a diamond cutter (with a flattened tip at a 50° apex and a flat section with a cross-sectional length of 40 μm) to obtain rollers E and F with multiple protrusions.

[0212] In roll E, a plurality of protrusions are formed in such a manner as follows: the protrusions extend at an angle of 45° to the upper right relative to a straight line on the roll circumferential surface parallel to the roll axis, and the spacing between the protrusions is 50 μm, and further, on a cross section perpendicular to the direction of extension of the protrusions, the angle of the apex of the protrusions is 50°.

[0213] In roll F, a plurality of protrusions are formed in such a manner as follows: the protrusions extend at an angle of 45° to the upper left relative to a straight line on the roll circumferential surface parallel to the roll axis, and the spacing between the protrusions is 50 μm, and further, on a cross section perpendicular to the direction of extension of the protrusions, the angle of the apex of the protrusions is 50°.

[0214] The depth of the cut portion (height of the protrusion) of each roller was measured using a laser microscope and found to be 10.7 μm.

[0215] The powder was obtained by replacing the cracked rollers A and B with the cracked rollers E and F respectively, otherwise operating in the same manner as in Example 1.

[0216] For roller F after the crack formation process, the adhesion status of the release liner is evaluated using the method described above. The expected result is that a large amount of release liner adheres, making it difficult to efficiently obtain the release liner.

[0217] In the table below, the abbreviations have the following meanings.

[0218] "Cholesteric resin layer": the cured layer of the liquid crystal composition

[0219] "Al film": vapor-deposited aluminum film

[0220] [Table 1]

[0221] Example 1 Example 2 Example 3 Comparative Example 1 film Cholesteric resin layer Cholesteric resin layer Al membrane Cholesteric resin layer Film thickness T (μm) 3.5 3.5 12 3.5 Convex height (μm) 4.3 4.3 14 10.7 Projection height / film thickness T 1.22 1.22 1.16 3.05 The shape of the small piece square rectangle hexagon square Peeling sheet adhesion good good good bad

[0222] In the manufacturing method of Comparative Example 1, where a protrusion with a height greater than 1.5Tμm is formed on the surface of the roller used to generate cracks, a large amount of release sheet adheres to the roller, resulting in inefficient production of release sheets. On the other hand, in the manufacturing method of the embodiment using a roller with a protrusion with a height of 1.1Tμm or more but less than 1.5Tμm, no release sheet adheres to the roller, enabling efficient production of release sheets. Here, the film thickness is defined as T.

[0223] Explanation of reference numerals in the attached figures

[0224] 10: Multilayer film; 100C2: Crack;

[0225] 11: Thin film; 100 Cd: Depth;

[0226] 12: Substrate layer; 100Ct: Top layer;

[0227] 100: Multilayer film; 101: Small sheet;

[0228] 100C: Cracking; 110: Thin film;

[0229] 100C1: Crack; 110T: Thickness;

[0230] 110U: Surface; 1110t: Vertex;

[0231] 120: Substrate layer; 1110D: Recess;

[0232] 120U: Surface; 1111: End;

[0233] 200: Multilayer film; 1112: End point;

[0234] 200C: Cracking; 1115: Roller;

[0235] 200Ct: Top; 1115T: Convex portion;

[0236] 201: small piece; 1115T1: convex part;

[0237] 210: film; 1115T2: convex part;

[0238] 220: Substrate layer; 1115t: Vertex;

[0239] 220U: Surface; 1115D: Concave;

[0240] 1110: Roller; 1116: End;

[0241] 1110T: convex part; 1117: end part;

[0242] 1110T1: Protrusion; 1120: Supporting component;

[0243] 1110T2: Protrusion; 1125: Supporting component.

Claims

1. A method for manufacturing powder, comprising the following steps: Step 1 involves forming cracks on a multilayer film comprising a substrate layer and a thin film disposed on the outermost side. The cracks are defined as cracks that, when viewed from the thickness direction of the film, divide the film into small pieces of the same shape, and the cracks extend deeper into the substrate layer than the surface of the thin film side. Step 2 involves peeling small pieces of the film from the substrate layer where the cracked multilayer film is formed, to obtain powder containing the small pieces of the film. The process 1 includes a process 1a in which the circumferential surface of the roller is pressed against the thin film side surface of the multilayer film. The roller has a protrusion on its circumferential surface, the height of which is 1.1Tμm or more and 1.5Tμm or less, where T is a value representing the thickness of the film in μm, and T is 0.1μm or more and 20μm or less.

2. The method for manufacturing powder according to claim 1, wherein, The circumferential surface of the roller located between the protrusions is flat.

3. The method for manufacturing powder according to claim 1, wherein, In step 1a, the pressure applied to the circumferential surface of the roller is 0.5 MPa or more.

4. The method for manufacturing powder according to claim 1, wherein, The pressing in step 1a is performed with the multilayer film supported by a support member having a surface hardness of D40 or higher.

5. The method for manufacturing powder according to claim 1, wherein, The major diameter of the small piece is less than 150 μm.

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