Apparatus and method for manufacturing powder

Abstract

This roll is for forming, in a multilayer film including a base material layer and a thin film disposed on the outermost side, a crack in the thin film by pressing the thin film-side surface of the multilayer film. The roll has convexities on the circumferential surface thereof, wherein the height of the convexities is 1.1-1.5 Tμm, and T represents the thickness (μm) of the thin film.

Description

[Technical Field]

[0001] The present invention relates to a roll and a method for producing powder. [Background Art]

[0002] As an ink pigment, powder composed of thin film pieces formed from a thin film made of metal, resin, or the like is sometimes used. For producing resin thin film pieces, a method is known in which a release layer is formed on a base film, a resin thin film is formed on the release layer, cracks are formed in the resin thin film, and then the base film is bent at an acute angle to peel off the resin thin film as thin film pieces (see Patent Document 1). A method is also known in which a resin thin film is formed on a base film, a member having an uneven shape is pressed against the resin thin film to form cracks in the resin thin film, and a fluid is sprayed onto the cracked resin thin film to peel off the resin thin film (see Patent Document 2). [Prior Art Documents] [Patent Documents]

[0003] [Patent Document 1] Japanese Examined Patent Publication No. 07-080248 [Patent Document 2] International Publication No. WO 2019 / 189246 (corresponding foreign publication: US Patent Application Publication No. 2021 / 0115336 Specification) [Summary of the Invention] [Problem to be Solved by the Invention]

[0004] As in the technique of Patent Document 2, when a member having an uneven shape is pressed against a thin film on a base film to form cracks in the thin film, thin film pieces may adhere to the surface of the member having the uneven shape when the member is separated from the thin film. If thin film pieces adhere to the surface of the member having the uneven shape, when the member is used continuously, the accuracy of crack formation may deteriorate, or it becomes necessary to frequently clean the member, which may reduce productivity.

[0005] Using a roll as a component with an uneven surface has the advantage of being able to continuously form cracks in the thin film. However, as mentioned above, if thin film fragments adhere to the roll and frequent cleaning becomes necessary, this advantage is lost.

[0006] Therefore, there is a need for a roll that does not easily leave small fragments of the thin film when separating it after forming cracks in the thin film by pressing, and a method for producing powder that uses such a roll to obtain powder containing small fragments of the thin film. [Means for solving the problem]

[0007] In order to solve the aforementioned problem, the inventors conducted thorough research and found that the adhesion of small pieces of thin film to the roll is related to the height of the protrusions on the roll. Without limiting the present invention, the inventors have inferred the following reason why the adhesion of small pieces of thin film to the roll is related to the height of the protrusions on the roll. If the height of the protrusions on the roll is too great compared to the thickness of the thin film to be cracked, the degree to which the thin film is deformed and compressed between the protrusions when the roll is pressed will increase, making it difficult for small pieces of the thin film to detach as they are trapped between the protrusions. As a result, it is thought that more small pieces of the thin film will adhere to the roll. On the other hand, if the height of the protrusions on the roll is the same as the thickness of the thin film to be cracked, it is thought that it will be difficult to stably crack the thin film.

[0008] Based on the above findings, the inventors discovered that by setting the height of the protrusions on the roll within a predetermined range, the adhesion of small pieces of thin film to the roll can be reduced, thus completing the present invention. In other words, the present invention provides the following:

[0009] [1] A roll for pressing against the thin film side of a multilayer film comprising a base layer and an outermost thin film to form a crack in the thin film, A roll having 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 thin film. [2] A step (1) of forming a crack in a multilayer film comprising a base layer and an outermost thin film, the crack being such that the thin film is divided into small pieces of the same shape when viewed in the thickness direction and the crack reaches a position deeper than the surface of the base layer on the thin film side, The process includes (2) peeling off small pieces of the thin film from the substrate layer of the multilayer film in which the cracks have been formed, in order to obtain a powder containing the small pieces of the thin film. The above step (1) includes a step (1a) of pressing the circumferential surface of the roll against the thin film side of the multilayer film, A method for manufacturing powder, wherein the roll 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 thin film. [3] The method for producing powder according to [2], wherein the circumferential surface between the protrusions of the roll is flat. [4] The method for producing the powder according to [2] or [3], wherein the thickness T of the thin film is 0.1 μm or more and 20 μm or less. [5] The method for producing powder according to any one of [2] to [4], wherein in step (1a), the pressure applied to the circumferential surface of the roll is 0.5 MPa or more. [6] A method for producing powder according to any one of [2] to [5], wherein the pressing in step (1a) is performed while the multilayer film is supported by a support member having a surface hardness of D40 or higher. [7] The method for producing powder according to any one of [2] to [6], wherein the major axis of the small piece is 150 μm or less. [Effects of the Invention]

[0010] According to the present invention, a roll is provided that, after forming cracks in a thin film by pressing, does not easily leave small fragments of the thin film on it when it is separated from the thin film; and a method for producing powder is provided, which involves using such a roll to obtain powder containing small fragments of the thin film. [Brief explanation of the drawing]

[0011] [Figure 1] Fig. 1 is a cross-sectional view showing an example of the multilayer film used in step (1) according to one embodiment. [Figure 2] Fig. 2 is a schematic plan view, as viewed from the thickness direction of the multilayer film, of the thin-film side surface of the multilayer film in which cracks are formed according to one embodiment. [Figure 3] Fig. 3 is a cross-sectional view schematically showing the III-III cross-section of Fig. 2. [Figure 4] Fig. 4 is a schematic plan view, as viewed from the thickness direction of the multilayer film, of the thin-film side surface of the multilayer film in which cracks are formed according to one embodiment. [Figure 5] Fig. 5 is a cross-sectional view schematically showing the V-V cross-section of Fig. 4. [Figure 6] Fig. 6 is a perspective view schematically showing an example of a roll that can be used in the powder production method according to one embodiment. [Figure 7] Fig. 7 is a perspective view schematically showing the roll shown in Fig. 6. [Figure 8] Fig. 8 is a plan view schematically showing a developed state of the roll of Fig. 7 cut along line X1-X1. [Figure 9] Fig. 9 is a partial cross-sectional view taken along line Y1-Y1 of Fig. 8. [Figure 10] Fig. 10 is a perspective view schematically showing an example of a roll that can be used in the powder production method according to one embodiment. [Figure 11] Fig. 11 is a perspective view schematically showing the roll shown in Fig. 10. [Figure 12] Fig. 12 is a plan view schematically showing a developed state of the roll of Fig. 11 cut along line X2-X2. [Figure 13] Fig. 13 is a partial cross-sectional view taken along line Y2-Y2 of Fig. 12. MODE FOR CARRYING OUT THE INVENTION

[0012] The present invention will be described in detail below with reference to embodiments and examples. However, the present invention is not limited to the embodiments and examples shown below, and can be modified and implemented as appropriate without departing from the scope of the claims and equivalents of the present invention. The components of the embodiments shown below can be combined as appropriate. In addition, in the figures, the same reference numerals are used for the same components, and their descriptions may be omitted.

[0013] In the following description, "long film" refers to a film having a length of five times or more its width, preferably 10 times or more its width, and specifically a film long enough to be rolled up for storage or transport. There is no particular upper limit to the length of the film; for example, it may be 100,000 times or less its width.

[0014] In the following explanation, the term "(meth)acrylic" includes "acrylic," "methacrylic," and combinations thereof.

[0015] In the following description, the orientation of the elements being "parallel" and "perpendicular" may include errors within a range that does not impair the effects of the present invention, for example, within the range of ±3°, ±2°, or ±1°, unless otherwise specified.

[0016] [1. Overview of powder manufacturing methods using rolls] A roll according to one embodiment of the present invention is used to press against the thin film side of a multilayer film, which includes a substrate layer and an outermost thin film, in order to form a crack in the thin film.

[0017] The roll of this embodiment can be used in a method for manufacturing powder, which includes the following steps (1) and (2). More specifically, it can be used in step (1a), which is included in step (1) below.

[0018] In step (1), a crack is formed in the multilayer film, which includes a base layer and the outermost thin film, that divides the thin film into small pieces of the same shape when viewed from its thickness direction, and that reaches a position deeper than the surface of the base layer on the thin film side.

[0019] In step (1a) included in step (1), the circumferential surface of a roll is pressed against the thin film side of the multilayer film. The roll 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 thin film.

[0020] In step (2), small pieces of the thin film are peeled off from the substrate layer of the multilayer film in which the cracks have been formed, to obtain a powder containing the small pieces of the thin film.

[0021] In a powder manufacturing method, using a predetermined roll can reduce the amount of small fragments of the thin film adhering to the roll. As a result, the frequency of roll cleaning can be reduced, improving the productivity of the powder.

[0022] [2. Process (1)] In step (1), a crack is formed in the multilayer film, which includes a base layer and the outermost thin film, that divides the thin film into small pieces of the same shape when viewed from its thickness direction, and that reaches a position deeper than the surface of the base layer on the thin film side.

[0023] [2.1. Multilayer film] The multilayer film used in step (1) includes a substrate layer and a thin film. The thin film is located on the outermost layer of the multilayer film. Here, "outermost layer" means that the thin film is located on the outermost layer in 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 have any layer between the thin film and the substrate layer. The multilayer film is preferably long in order to efficiently form cracks. Figure 1 is a cross-sectional view showing an example of a multilayer film used in step (1) according to one embodiment. As shown in Figure 1, the multilayer film 10 includes a base layer 12 and a thin film 11 directly provided on the base layer 12. The thin film has a thickness T.

[0024] (base material layer) The substrate layer is preferably long in order to efficiently form a thin film. Examples of materials for forming the base layer are not particularly limited and include polymer-containing resins, paper, and metals. Polymer-containing resins are preferred because they have excellent flexibility and mechanical strength. Examples of polymers that can be included in a resin that can form a base layer include cellulosic polymers (e.g., triacetylcellulose); polymers containing alicyclic structures (e.g., cycloolefin polymers); polyesters (e.g., polyethylene terephthalate); acrylic polymers (e.g., poly(meth)acrylic acid, poly(meth)acrylic acid esters, polyacrylonitrile); and polycarbonates. The resin that can form a base layer may contain a single polymer or a combination of two or more polymers. The polymer may be a homopolymer or a copolymer. In addition to polymers, the resin may contain any additives.

[0025] Examples of polymers containing alicyclic structures include (1) norbornene polymers, (2) monocyclic 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 moldability.

[0026] Examples of norbornene polymers include ring-opening polymers of monomers having a norbornene structure and their hydrides; and 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 one type of monomer having a norbornene structure, ring-opening copolymers of two or more types of monomers having a norbornene structure, and ring-opening copolymers of monomers having a norbornene structure and any monomer copolymerizable therewith. Additionally, examples of addition polymers of monomers having a norbornene structure include addition homopolymers of one type of monomer having a norbornene structure, addition copolymers of two or more types of monomers having a norbornene structure, and addition copolymers of monomers having a norbornene structure and any monomer copolymerizable therewith. Examples of these polymers include those disclosed in Japanese Patent Application Publication No. 2002-321302, etc.

[0027] Suitable examples of norbornene polymers and their hydrides include "Zeonor" manufactured by Zeon Corporation; "Arton" manufactured by JSR Corporation; and "TOPAS" manufactured by TOPAS Advanced Polymers.

[0028] The thickness of the base 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. A base layer thickness greater than or equal to the lower limit can improve the mechanical strength of the base layer. A base layer thickness less than or equal to the upper limit can improve the flexibility of the base layer and facilitate handling during manufacturing.

[0029] The base layer may have a single-layer structure or a multi-layer structure.

[0030] If the base layer has a multilayer structure, it is preferable that each layer included in the base layer has a peel strength such that it does not peel off from each other in steps (1) and (2). The base layer preferably has a single-layer structure.

[0031] The substrate layer may have been treated on its surface, such as rubbing or corona treatment. The base layer may be an unstretched layer or a stretched layer.

[0032] The multilayer film may consist only of a substrate layer and a thin film, or it may include any additional layer in addition to the substrate layer and the thin film. For example, when a liquid crystal composition is used as the composition for forming the thin film, the multilayer film may have an alignment film between the substrate layer and the thin film, from the viewpoint of properly aligning the liquid crystal composition. The alignment film can be formed from a resin containing polymers such as polyimide, polyvinyl alcohol, polyester, polyarylate, polyamideimide, polyetherimide, and polyamide. These polymers may be used individually or in combination of two or more in any ratio. The alignment film can be manufactured by applying a solution containing the polymers, drying it, and then performing a rubbing treatment.

[0033] (Thin film) The thin film may have either a single-layer or multilayer structure. Furthermore, the thin film may be either a conductor or a dielectric. Additionally, the thin film may be either an inorganic or organic film. Examples of thin films include metal films such as aluminum and silver; dielectric multilayer films formed from dielectric materials such as titanium oxide, silicon oxide, niobium oxide, tantalum oxide, and magnesium fluoride; and resin films.

[0034] Examples of resin materials for forming resin films include photocurable liquid crystal compositions, acrylic resins, polystyrene, polyester, polyamide, polyvinyl chloride, polyvinyl acetate, cellulosic polymers (e.g., triacetylcellulose), polycarbonate, polyurethane, polyolefin, alicyclic structure-containing polymers, epoxy resins, melamine resins, phenolic resins, and combinations thereof. The polymers contained in the resin material may be homopolymers or copolymers. In addition to polymers, the resin material may contain optional additives such as curing agents and antioxidants.

[0035] The thickness T of the thin film can be appropriately set depending on the material of the thin film and the intended use of the powder, but from the viewpoint of ensuring the reflectivity of the thin 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 setting the thickness of the thin film to the above upper limit, the resulting powder can be suitably used in inks corresponding to printing layers of various thicknesses.

[0036] When the thickness T of the thin film is small, small pieces of the thin film tend to adhere to the roll. However, by using the roll according to this embodiment, even when the thickness T of the thin film is small (for example, when the thickness T of the thin film 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 the thin film to the roll can be reduced.

[0037] As a thin film, for example, a film made from a cured product obtained by curing a photocurable liquid crystal composition as a resin-containing composition may be used. That is, as the resin forming the thin film, for example, a cured product of a photocurable liquid crystal composition may be used. Here, for convenience, the material referred to as "liquid crystal composition" includes not only mixtures of two or more substances, but also materials made from a single substance.

[0038] Furthermore, a cholesteric resin layer may be used as the thin film. A cholesteric resin layer is a resin layer that has cholesteric regularity. Cholesteric regularity in a resin layer with cholesteric regularity is a structure in which, on one plane, the molecular axes are aligned in a certain direction, but on the next plane that overlaps it, the direction of the molecular axes is shifted by a slight angle, and on the next plane the angle is shifted even further, and so on, as the material passes through the overlapping planes in succession, the angle of the molecular axes in the plane is shifted (twisted). In other words, when the molecules in a layer have cholesteric regularity, the molecules align within the resin layer in a manner that forms a layer of many molecules. In a certain layer A of such a layer of many molecules, the molecules align so that the molecular axes are in a certain direction, in the adjacent layer B the molecules align in a direction that is shifted at an angle from the direction in layer A, and in the further adjacent layer C the molecules align in a direction that is shifted at an angle from the direction in layer B. In this way, a structure is formed in which the angles of the molecular axes are continuously shifted across multiple layers of molecules, causing the molecules to twist. A structure in which the direction of the molecular axes is twisted in this manner becomes an optically chiral structure.

[0039] Cholesteric resin layers typically possess circular polarization separation capabilities. That is, they transmit one type of circularly polarized light (right-circularly polarized or left-circularly polarized) while reflecting some or all of the other type. Furthermore, the reflection in the cholesteric resin layer reflects circularly polarized light while maintaining its chirality.

[0040] When a cholesteric resin layer as described above is used as the thin film, the manufacturing method of this embodiment makes it possible to produce a powder consisting of small pieces of resin film that utilize the circular polarization separation function, with a large proportion of thin film pieces having a certain shape.

[0041] Thin films can be formed by any method depending on the material of the thin film. For example, thin films can be formed by vapor deposition, sputtering, coating, etc. Examples of coating methods include die coating, curtain coating, extrusion coating, roll coating, spin coating, dip coating, bar coating, spray coating, slide coating, print coating, gravure coating, and gap coating.

[0042] [2.2. Crack Formation] (crack) The cracks formed in step (1) divide the thin film contained in the multilayer film into small pieces of the same shape when viewed from the thickness direction. Furthermore, the cracks are formed to reach a position deeper than the surface of the thin film side of the substrate layer. Moreover, the cracks are formed across the entire surface of the multilayer film to reach a position deeper than the surface of the thin film side of the substrate layer.

[0043] The shape of the small pieces viewed from the thickness direction of the thin film is not particularly limited and includes polygons such as triangles, quadrilaterals, and hexagons, as well as cross shapes and circles, with triangles, quadrilaterals, or hexagons being preferred.

[0044] The major axis of a small piece, viewed from the thickness direction of the thin 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 suppressing ink clogging on the printing plate. From the viewpoint of improving the visibility of the printed layer formed by the ink, it is usually greater than 0 μm, and preferably 10 μm or more. Here, the major axis refers to the longest distance among the distances between parallel lines drawn so as to be tangent to the contour of the small piece.

[0045] The following describes examples of cracks formed in process (1). Figure 2 is a schematic plan view of the thin-film side of a cracked multilayer film according to one embodiment, as seen from the thickness direction of the multilayer film. Figure 3 is a schematic cross-sectional view showing the III-III section of Figure 2.

[0046] As shown in Figure 2, a grid-like crack pattern 100C is formed in the multilayer film 100. The crack pattern 100C consists of multiple linear notches 100C1 extending downward to the right at an angle θ1 with respect to the width direction WD of the multilayer film 100, and multiple linear notches 100C2 extending upward to the right at an angle θ2. Here, if we consider the clockwise direction as positive and the counterclockwise direction as negative with respect to the width direction WD of the multilayer film 100 in Figure 2, then θ1 is 45° and θ2 is -45°.

[0047] In this embodiment, the spacing P11 between adjacent notches 100C1 is approximately the same as the spacing P12 between adjacent notches 100C2. Here, "approximately the same" means that P12 is between 90% and 110% of P11. The grid-like cracks 100C, which have multiple notches 100C1 and multiple notches 100C2, divide the thin film located on the outermost part of the multilayer film 100 into multiple approximately square pieces 101. The multiple pieces 101 have sides with lengths corresponding to the spacings P11 and P12, and in this embodiment, the length of one side of the multiple pieces 101 is P11.

[0048] As shown in Figure 3, the multilayer film 100 comprises a base layer 120 and a thin film 110 directly formed on the base layer 120. The depth 100Cd of the crack 100C is the distance from the surface 110U of the multilayer film 100 on the thin film 110 side 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 deeper than the surface 120U of the base layer 120 on the thin film 110 side.

[0049] Figure 4 is a schematic plan view of the thin-film side of a multilayer film in which a crack has been formed, as seen from the thickness direction of the multilayer film. Figure 5 is a schematic cross-sectional view showing the VV cross-section of Figure 4.

[0050] As shown in Figure 4, 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 several small pieces 201 that are roughly hexagonal. As shown in Figure 5, the multilayer film 200 comprises a base layer 220 and a thin film 210 directly formed on the base layer 220. In this embodiment as well, the tip 200Ct of the crack 200C reaches a position deeper than the surface 220U of the base layer 220 on the thin film 210 side.

[0051] In another embodiment, a series of triangular cracks may be formed in the multilayer film when viewed from the thickness direction of the multilayer film.

[0052] (Step (1a)) In step (1a), the circumferential surface of the roll is pressed against the thin film side of the multilayer film. This can cause cracks to form in the thin film contained within the multilayer film. Here, the roll has a protrusion on its circumferential surface, the height of which is usually 1.1Tμm or more, preferably 1.15Tμm or more, more preferably 1.20Tμm or more, and usually 1.5Tμm or less, preferably 1.45Tμm or less, more preferably 1.40Tμm or less, where T represents the thickness of the thin film (μm). In another embodiment, the roll has a protrusion height that 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, and more preferably 10.0μm or less.

[0053] The height of the protrusion on the roll refers to the height of the protrusion relative to the deepest point on the roll's circumferential surface (the point closest to the roll's axis).

[0054] In step (1a), a roll having protrusions on its circumferential surface corresponding to the shape of the cracks as viewed from the thickness direction of the multilayer film may be used. For example, if the shape of the cracks as viewed from the thickness direction of the multilayer film is grid-like, a roll having grid-like protrusions on its circumferential surface may be used. Also, if the shape of the cracks as viewed from the thickness direction of the multilayer film is honeycomb-like, a roll having honeycomb-like protrusions on its circumferential surface may be used.

[0055] Furthermore, step (1a) may be repeated multiple times. For example, a first step (1a) may be performed using a roll having a protrusion on its circumferential surface corresponding to a part of the crack, and a second step (1a) may be performed using a roll having a protrusion on its circumferential surface corresponding to another part of the crack. For example, if the crack is lattice-shaped and divides the thin film into squares when viewed from its thickness direction, the crack may be formed by pressing a first roll having a protrusion on its circumferential surface corresponding to notches in one direction that constitute the crack, and a second roll having a protrusion on its circumferential surface corresponding to notches in another direction that constitute the crack, onto the multilayer film.

[0056] The roll material may be a material that has sufficient strength to prevent damage when a multilayer film is pressed against it and that can form an uneven surface. Examples of such materials include carbon steel and stainless steel. The roll may also have one or more multilayer coatings on its surface for purposes such as improving corrosion resistance, strength, and thermal conductivity. Such coatings are not particularly limited, but examples include plating coatings of nickel, nickel-phosphorus, silicon, copper, etc., and coatings formed by ceramic thermal spraying. The roll may be equipped with heating means such as heaters, heat transfer fluids, dielectric heating, induction heating, etc., as well as static electricity eliminators and grounding devices for static electricity countermeasures.

[0057] The rolls can be manufactured by any conventionally known method. For example, a cylindrical metal roll or other component can be cut using a cutting tool such as a diamond bit, or processed using a laser processing device to form a roll with a desired uneven shape.

[0058] The pressure applied when pressing the roll 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 setting the pressure above the lower limit, cracks of sufficient depth can be formed in the multilayer film, and by setting the pressure below the upper limit, damage to the multilayer film can be suppressed. When pressing a roll having one or more types of uneven shapes against the multilayer film multiple times in order to form cracks in the multilayer film, the multiple presses may be the same or different. Preferably, the multiple presses are performed at the same pressure.

[0059] It is preferable to support the multilayer film with a support member, sandwich the multilayer film between the support member and a roll having a protrusion, and then press the roll having the protrusion.

[0060] The support member typically has a support surface that supports the side of the multilayer film opposite to the side containing the thin film. The hardness of the support surface that supports the surface of 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. Here, the hardness is a value measured by a durometer (type D) in accordance with JIS K-6253. By setting the hardness of the support surface of the support member within the above range, cracks of an appropriate depth can be easily formed in the multilayer film. As the support member, a material having sufficient strength to prevent damage even when the multilayer film is pressed by a roll can be used. Examples of the surface material of the support member include rubber and resin.

[0061] The shape of the support member can be any shape (e.g., roll shape, flat plate shape) depending on, for example, the method of transporting the multilayer film and the method of pressing the member with an uneven shape onto the multilayer film. Since a long length of multilayer film can be used to continuously form cracks in the multilayer film, the support member is preferably roll-shaped.

[0062] The following describes an example of a roll having a protrusion and a process (1) using such a roll.

[0063] Figure 6 is a schematic perspective view showing an example of a roll that can be used in the powder manufacturing method of this embodiment. Figure 7 is a schematic perspective view showing the roll shown in Figure 6. Figure 8 is a schematic plan view showing the member of Figure 7 cut along the line X1-X1 and unfolded. Figure 9 is a partial cross-sectional view of Figure 8 along the line Y1-Y1. Figure 10 is a schematic perspective view showing an example of a roll that can be used in the powder manufacturing method of this embodiment. Figure 11 is a schematic perspective view showing the roll shown in Figure 10. Figure 12 is a schematic plan view showing the member of Figure 11 cut along the line X2-X2 and unfolded. Figure 13 is a partial cross-sectional view of Figure 12 along the line Y2-Y2.

[0064] As shown in Figure 6, roll 1110 is positioned to contact the thin film 11 side of the multilayer film 10 and presses the multilayer film 10. Also, as shown in Figure 10, roll 1115 is positioned to contact the thin film 11 side of the multilayer film 10 and presses the multilayer film 10. The order in which roll 1110 and roll 1115 press the multilayer film 10 is not particularly limited. For example, the multilayer film 10 may be pressed by roll 1110 and then by roll 1115, or the multilayer film 10 may be pressed by roll 1115 and then by roll 1110.

[0065] The circumferential surface of roll 1110 (the surface that contacts the multilayer film 10) has a protrusion, as shown in Figure 6. The circumferential surface of roll 1115 also has a protrusion, as shown in Figure 10. Rolls 1110 and 1115 are cylindrical, as shown in Figures 6 and 10, and are capable of rotational movement on the multilayer film 10.

[0066] The support member 1120, which is positioned on the base material layer 12 side of the multilayer film 10, is a member that presses the multilayer film 10 together with the roll 1110. The support member 1125, positioned on the base layer 12 side of the multilayer film 10, is a member that presses the multilayer film 10 together with the roll 1115. The support members 1120 and 1125 are each cylindrical and can rotate on the underside of the multilayer film 10.

[0067] Of the surfaces of the multilayer film 10, the surface that contacts the rolls 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 the roll 1110 and the support member 1120, the protrusion 1110T of the roll 1110 comes into contact with the thin film 11. When the multilayer film 10 is compressed while sandwiched between the roll 1110 and the support member 1120, the protrusion 1110T of the roll 1110 penetrates into the thin film 11 and the base layer 12, forming notches 100C1 that constitute the crack 100C. Furthermore, when the multilayer film 10 is sandwiched between the roll 1115 and the support member 1125, the protrusion 1115T of the roll 1115 comes into contact with the thin film 11. By pressing the multilayer film 10 while sandwiched between the roll 1115 and the support member 1125, the protrusions 1115T of the roll 1115 penetrate into the interior of the thin film 11 and the base layer 12, forming notches 100C2 that constitute the crack 100C. In this way, a multilayer film 10 with the crack 100C formed is obtained (see Figures 2 and 3).

[0068] The circumferential surface of the roll 1110 has protrusions, which create an uneven surface. As shown in Figure 8, the uneven surface is formed by alternatingly repeating protrusions 1110T and recesses 1110D that extend in a direction inclined by an angle θx with respect to the direction indicated by L1, in a direction perpendicular to the direction in which the protrusions 1110T are formed. θx is not particularly limited and can be, for example, 45°. As shown in Figure 8, the uneven surface of the roll 1110, when viewed from the plane of the paper, is a shape of straight lines sloping downwards to the right. The distance between two adjacent protrusions 1110T (the distance Q1 between protrusions 1110T1 and 1110T2 shown in Figure 9) can be set as appropriate. In Figures 7 and 8, the ends 1111 and 1112 are the ends of the roll 1110.

[0069] As shown in Figure 9, the convex portion 1110T may have a mountain shape with an acute-angled vertex 1110t in cross-sectional view. In Figure 9, θ11 is the angle of the vertex of the convex portion. A small θ11 is preferable, but it can be, for example, 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 convex portion 1110T may be rounded or chamfered, as long as it is possible to form cracks in the thin film and the substrate layer.

[0070] As shown in Figure 9, the height H1 of the protrusions 1110T1 and 1110T2 refers to the height of the protrusions relative to the deepest position P (the position closest to the axis of the roll) on the circumferential surface 1110S of the roll 1110. The height H1 is usually between 1.1Tμm and 1.5Tμm. Here, T represents the thickness (μm) of the thin film 11.

[0071] As shown in Figure 9, the circumferential surface between adjacent protrusions 1110T1 and 1110T2 is flat. This prevents the protrusions 1110T1 and 1110T2 from being pressed excessively deeply into the multilayer film 10 beyond their respective heights when the roll 1110 is pressed against the thin film 11 side of the multilayer film 10. As a result, the adhesion of small pieces of the thin film to the roll 1110 can be further reduced.

[0072] The circumferential surface of the roll 1115 has protrusions, which create an uneven surface. As shown in Figure 12, the uneven surface is formed by alternatingly repeating protrusions 1115T and recesses 1115D that extend in a direction inclined by an angle θy with respect to the direction indicated by L2, in a direction perpendicular to the direction in which the protrusions 1115T are formed. θy is not particularly limited and can be, for example, 45°. As shown in Figure 12, the uneven surface of the roll 1115, when viewed from the plane of the paper, is a shape of straight lines sloping upwards to the right. The distance between two adjacent protrusions 1115T (the distance Q2 between protrusions 1115T1 and 1115T2 shown in Figure 13) can be set as appropriate. In Figures 11 and 12, the ends 1116 and 1117 are the ends of the roll 1115.

[0073] The protrusion 1115T may have a mountain shape with an acute-angled vertex 1115t in cross-sectional view, as shown in Figure 13. In Figure 13, θ12 is the angle of the vertex of the protrusion. A small θ12 is preferable, but it can be, for example, 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 may be rounded or chamfered, as long as it is possible to form cracks in the thin film and the substrate layer.

[0074] As shown in Figure 13, the height H2 of the protrusions 1115T1 and 1115T2 refers to the height of the protrusions relative to the deepest position P (the position closest to the axis of the roll) on the circumferential surface 1115S of the roll 1115. The height H2 is usually between 1.1Tμm and 1.5Tμm. Here, T represents the thickness (μm) of the thin film 11.

[0075] As shown in Figure 13, the circumferential surface between adjacent protrusions 1115T1 and 1115T2 is flat, similar to the roll 1110. This further reduces the adhesion of small pieces of the thin film to the roll 1115 for the same reasons explained for the roll 1110.

[0076] By performing step (1), cracks are formed in the multilayer film (for example, as shown in Figures 3 and 5, cracks 100C or 200C are formed in the multilayer film 10). The multilayer film in which cracks have been formed (for example, multilayer films 100, 200) is then subjected to step (2).

[0077] The shape of the cracks reflects the shape of the protrusions on the roll. For example, when a roll 1110, whose unfolded shape is as shown in Figure 8, is positioned so that the L1 direction in Figure 8 is parallel to the longitudinal direction of the multilayer film and pressed, notches can be formed diagonally to the longitudinal direction of the multilayer film 10. Subsequently, when a roll 1115, whose unfolded shape is as shown in Figure 12, is positioned so that the L2 direction in Figure 12 is parallel to the longitudinal direction of the multilayer film and pressed, a grid-like crack 100C as shown in Figure 2 can be formed. In Figure 2, the downward-sloping linear notches 100C1 reflect the shape of the protrusions on the roll 1110, and the upward-sloping linear notches 100C2 reflect the shape of the protrusions on the roll 1115.

[0078] As described above, the rolls 1110 and 1115 used in the manufacturing method of this embodiment have a height of the protrusions on their circumferential surface that is typically between 1.1 T μm and 1.5 T μm. This reduces the adhesion of small pieces of the thin film to the rolls.

[0079] If the height of the protrusions on the roll is too great compared to the thickness of the thin film to be cracked, the degree to which the thin film is deformed and compressed between the protrusions when the roll is pressed will be greater, and small pieces of the thin film may become trapped between the protrusions and have difficulty detaching. As a result, a large amount of small pieces of the thin film may adhere to the roll. On the other hand, if the height of the protrusions on the roll is the same as the thickness of the thin film to be cracked, it may become difficult to consistently crack the thin film.

[0080] Furthermore, as described above, the circumferential surfaces between adjacent protrusions of rolls 1110 and 1115 are flat. This prevents the protrusions from being pressed excessively deep into the multilayer film beyond their own height. As a result, the adhesion of small pieces of the thin film to the rolls can be further reduced.

[0081] Therefore, the rolls used in the manufacturing method of this embodiment do not need to be cleaned frequently, and powder can be manufactured with high productivity.

[0082] The extent to which small pieces of the thin film adhere to the roll can be evaluated, for example, by either method (1) or method (2) below.

[0083] Method (1) Observe the surface of the center of the roll using a microscope. Within a 1mm square area, measure the area of ​​the thin film present on the circumferential surface (recessed portion) of the roll, excluding the protruding portion. The smaller the area of ​​the thin film measured, the less likely it is that small fragments of the thin film will adhere to the roll.

[0084] Method (2) Observe the surface of the center of the roll using a microscope. Within a 1mm square area, count the number of small fragments of the thin film present on the circumferential surface (recessed area) of the roll, excluding the protruding parts. The fewer the number of thin film fragments counted, the less the thin film fragments adhere to the roll.

[0085] [3. Process (2)] In step (2), small pieces of the thin film are peeled off from the substrate layer of the multilayer film in which cracks have formed, to obtain a powder containing the small pieces of the thin film.

[0086] The method for peeling small pieces of the thin film from the substrate layer is not particularly limited and includes, for example: (1) a method of peeling off the small pieces by sliding a cracked multilayer film on a blade; (2) a method of peeling off the small pieces by blowing a fluid such as water or air onto a cracked multilayer film; (3) a method of peeling off small pieces of the thin film from the substrate layer by immersing a cracked multilayer film in a solvent (e.g., water) that does not easily dissolve the thin film (e.g., cholesteric resin layer) but dissolves the substrate layer or the layer existing between the thin film and the substrate layer (e.g., an alignment film formed of polyvinyl alcohol); (4) a method of peeling off small pieces of the thin film from the substrate layer by bonding the thin 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 thereof. In the method described in (4) above, a laminate having a layer structure of (transfer base film) / (water-soluble adhesive layer) / (cracked thin film) is obtained. By removing the water-soluble adhesive layer from this laminate, such as by immersing it in water at an appropriate temperature, a powder containing small pieces of the thin film can be obtained.

[0087] If the multilayer film with cracks is long in length, the powder can be efficiently produced by continuously performing the peeling process described above.

[0088] For example, step (2) may include step (2a) of spraying a fluid onto the multilayer film in which cracks have been formed. In step (2a), the fluid is sprayed onto the cracked side (i.e., the thin film side) of the multilayer film in which the cracks have formed. A known fluid discharge device can be used as the spraying device. The pressure of the fluid discharged from the fluid discharge device can be adjusted as appropriate depending on the density of the fluid, the peel strength between the substrate layer and the thin film, etc. The discharge pressure is not particularly limited, but is preferably 5 MPa or more, more preferably 10 MPa or more, preferably 50 MPa or less, and more preferably 35 MPa or less.

[0089] Step (2) may include step (2b) of passing the small pieces of the thin film through a sieve after peeling them off. For example, after the step of spraying a fluid onto a multilayer film in which cracks have formed (2a), the small pieces peeled off from the base layer may be passed through a filter having a predetermined mesh opening. Furthermore, step (2) may include step (2c) of recovering the small pieces after peeling off the small pieces of the thin film. For example, after the step of spraying a fluid onto a multilayer film in which cracks have formed (2a), the small pieces peeled off from the base layer may be guided to a recovery path along with the fluid, and the small pieces may be recovered by a recovery device to obtain a powder which is an aggregate of small pieces. As the recovery device, for example, a cyclone-type separator and various filters may be used.

[0090] [4. Properties of powders] The powder obtained by the manufacturing method of this embodiment has a high proportion of thin film fragments having a consistent shape along the cracks. This proportion can be evaluated, for example, by the following method. Prepare a 10% by weight aqueous dispersion of the powder. Drop the aqueous dispersion onto a microscope slide and allow the water to evaporate, causing the powder (thin film fragments) to adhere to the slide. Observe the area on the slide where the thin film fragments have adhered under a microscope. Count the number of thin film fragments of a consistent shape (A) and the number of thin film fragments of an irregular shape (B) within a 1 mm square area, and calculate the percentage X of the number of fragments (B) relative to the number of fragments (A) according to the following formula: X = B / A × 100 (%) The smaller the percentage X, the higher the proportion of thin film fragments that have a consistent shape along the crack.

[0091] The powder preferably has a percentage X of 5% or less, more preferably 4% or less, even more preferably 3% or less, and most preferably 0%, but it may also be 0% or more or 1% or more.

[0092] [5. Uses of powders] The powder produced by the manufacturing method of this embodiment has a high proportion of thin film fragments having a consistent shape along the cracks. Therefore, printed materials with good texture can be obtained using ink containing the powder. Furthermore, the authenticity of printed materials using ink containing the powder can be easily determined. Thus, the powder can be suitably used as an ink material. [Examples]

[0093] The present invention will be specifically described below with reference to examples. However, the present invention is not limited to the examples shown below, and can be modified and implemented as appropriate without departing from the scope of the claims and equivalents of the present invention.

[0094] In the following explanation, "%" and "parts" used to express quantities refer to weight unless otherwise specified. Furthermore, the operations described below are performed under normal temperature (20°C ± 15°C) and atmospheric pressure (1 atm) conditions unless otherwise specified.

[0095] [evaluation] (Attachment of peeling fragments) In each example, the surface of the center of the roll used to create the second crack is observed under a microscope. The number of detached fragments present in the depressions of the uneven surface is counted within a 1 mm square area. The fewer the number of detached fragments, the less detached fragments (small pieces) adhere to the roll, allowing for efficient and continuous crack creation. The adhesion of detached fragments is evaluated according to the following criteria. "Good": Number of detached pieces < 5 "Defective": Number of detached pieces ≥ 5

[0096] [Example 1] (1-1. Preparation of photocurable liquid crystal composition) A photocurable liquid crystal composition is prepared by mixing 18.1 parts of BASF's photopolymerizable liquid crystal compound "Paliocolor LC242", 1.3 parts of BASF's "LC756" as a chiral agent, 0.6 parts of Ciba Japan's "Irgacure OXEO2" as a photopolymerization initiator, 0.02 parts of Neos' "Futergent 209F" as a surfactant, and 80 parts of cyclopentanone.

[0097] (1-2. Manufacturing of long multi-layer films) A long cycloolefin polymer (COP) film (ZF16-100, manufactured by Nippon Zeon Co., Ltd.; 100 μm thick) is prepared as the base film. This base film is attached to the feed section of the film transport device, and the following operations are performed while the base film is transported in the longitudinal direction. First, a rubbing treatment is performed in the longitudinal direction parallel to the transport direction. Next, the liquid crystal composition prepared in (1-1) is applied to the rubbing treatment surface using a die coater. This forms a film of the uncured liquid crystal composition on one side of the base film.

[0098] The obtained liquid crystal composition film was subjected to an orientation treatment at 100°C for 5 minutes, and then the liquid crystal composition film was subjected to an 800 mJ / cm³ treatment under a nitrogen atmosphere. 2The liquid crystal composition film is completely cured by irradiation with ultraviolet light. This yields a multilayer film having a 3.5 μm thick resin thin film on one side of a long substrate film. The multilayer film has a layer structure of (substrate film as the substrate layer) / (resin thin film). The resin thin film functions as a cholesteric resin layer.

[0099] (1-3. Manufacturing of components (rolls) with uneven shapes) Prepare metal rolls made of stainless steel with electroless nickel plating (NiP plating) applied to the surface. Cut the surface of the plated rolls with a diamond cutting tool (with a flat tip at a 50° apex angle and a flat section with a cross-sectional length of 46 μm) to obtain rolls A and B having multiple protrusions. In roll A, multiple protrusions are formed such that they extend in a direction that forms a 45° upward-sloping angle with respect to a straight line on the roll surface parallel to the roll axis, and the pitch of the protrusions is 50 μm. Furthermore, in a cross section perpendicular to the direction in which the protrusions extend, the angle of the apex of the protrusions is 50°. In roll B, multiple protrusions are formed such that they extend in a direction that forms a 45° angle upward to the left with respect to a straight line on the roll surface parallel to the roll axis, and the pitch of the protrusions is 50 μm. Furthermore, in a cross section perpendicular to the direction in which the protrusions extend, the angle of the apex of the protrusions is 50°. When the cutting depth (height of the protrusion) of each roll was measured with a laser microscope, it was found to be 4.3 μm.

[0100] (1-4. Process (1): Crack formation process) The multilayer film produced in (1-2) is pressed with roll A, manufactured in (1-3), from the resin thin film side (pressing pressure 10 MPa), and then with roll B, also pressed (pressing pressure 10 MPa), to form cracks in the multilayer film. At this time, the side of the multilayer film opposite to the resin thin film (the base film side, the backup roll side) is supported by the backup roll. The backup roll used has a surface hardness of D70. Here, the hardness is the value measured using a durometer (type D) in accordance with JIS K-6253. The same applies below. This divides the resin thin film of the multilayer film into small square pieces (major axis 70 μm) with sides of 50 μm when viewed from the thickness direction of the resin thin film.

[0101] The state of debris adhesion to roll B after the crack formation process is evaluated using the method described above. As a result, it is predicted that there will be little debris adhesion.

[0102] (1-5. Process (2): Powder manufacturing process) Next, water is sprayed onto the cracked multilayer film from the resin thin film side at a discharge pressure of 60 MPa to peel off small pieces of the resin thin film from the base film.

[0103] Next, the small pieces of the peeled resin film are passed through a sieve with a nominal mesh size of 53 μm, and the pieces below the sieve are collected using a filter recovery device (3M Corporation, all-polypropylene filter) to obtain a powder containing the small pieces of the resin film.

[0104] [Example 2] (2-1~2-2) A long triacetylcellulose film (Konica Minolta's "KC6UY"; 60 μm thick) is used as the base film. Except for the above, the multilayer film is manufactured in the same manner as in (1-1) to (1-2) of Example 1.

[0105] (2-3. Manufacturing of components (rolls) with uneven shapes) A metal roll similar to that in Example 1 (1-3) is prepared, and the surface of the plated roll is cut with a diamond cutting tool (with a flat tip at a 50° apex angle and a flat section with a cross-sectional length of 96 μm) to obtain a roll C having multiple protrusions. In roll C, multiple protrusions are formed such that they extend in a direction that forms a 45° angle upward to the left with respect to a straight line on the roll surface parallel to the roll axis, and the pitch of the protrusions is 100 μm. When the cutting depth (height of the protrusion) of each roll was measured with a laser microscope, it was found to be 4.3 μm.

[0106] (2-4. Process (1): Crack formation process) The procedure is the same as in (1-4) of Example 1, except that roll C is used instead of roll B, to form cracks in the multilayer film. This divides the resin thin film of the multilayer film into small rectangular pieces (major axis 112 μm) measuring 50 μm × 100 μm when viewed from the thickness direction of the resin thin film.

[0107] The state of debris adhesion to roll C after the crack formation process is evaluated using the method described above. As a result, it is expected that there will be little debris adhesion.

[0108] (2-5. Process (2): Powder manufacturing process) The sieve opening through which the small pieces of the peeled resin film pass is changed from a nominal opening of 53 μm to a nominal opening of 106 μm. Except for the above, the powder is obtained in the same manner as in (1-5) of Example 1.

[0109] [Example 3] (3-1~3-2) As a multilayer film, a polyethylene terephthalate (PET) film with aluminum vapor deposition to a thickness of 12 μm (Toray Film Processing Co., Ltd.'s "VMPET1519") is prepared. The multilayer film has a layer structure of (aluminum film as a thin film) / (PET film as a base layer).

[0110] (3-3. Manufacturing of components (rolls) with uneven shapes) Prepare a metal roll similar to (1-3) in Example 1. Create indentations (dimple processing) on ​​the surface of the plated roll using an ultrashort pulse laser to obtain roll D. In roll D, the major axis is 50 μm, each side is 25 μm, and the depth of the recess (height of the protrusion) is 14 μm, forming a continuous hexagonal protrusion.

[0111] (3-4. Process (1): Crack formation process) Except for using roll D instead of roll A and not pressing the multilayer film with roll B, the procedure is the same as in (1-4) of Example 1 to form cracks in the multilayer film. This divides the aluminum film of the multilayer film into hexagonal pieces with a major axis of 50 μm and a side length of 25 μm when viewed from the thickness direction of the film.

[0112] The state of debris adhesion to roll D after the crack formation process is evaluated using the method described above. As a result, it is expected that there will be little debris adhesion.

[0113] (3-5. Process (2): Powder manufacturing process) A powder is obtained in the same manner as in (1-5) of Example 1.

[0114] [Comparative Example 1] (4-1. Manufacturing of components (rolls) with uneven shapes) A metal roll made of stainless steel with electroless nickel plating (NiP plating) applied to its surface is prepared. The surface of the plated roll is cut with a diamond cutting tool (with a flattened tip at a 50° apex angle and a flat section with a cross-sectional length of 40 μm) to obtain rolls E and F having multiple protrusions. In roll E, multiple protrusions are formed such that they extend in a direction that forms a 45° angle upward to the right with respect to a straight line on the roll surface parallel to the roll axis, and the pitch of the protrusions is 50 μm. Furthermore, in a cross section perpendicular to the direction in which the protrusions extend, the angle of the apex of the protrusions is 50°. In roll F, multiple protrusions are formed such that they extend in a direction that forms a 45° angle upward to the left with respect to a straight line on the roll surface parallel to the roll axis, and the pitch of the protrusions is 50 μm. Furthermore, in a cross section perpendicular to the direction in which the protrusions extend, the angle of the apex of the protrusions is 50°. When the cutting depth (height of the protrusion) of each roll was measured with a laser microscope, it was found to be 10.7 μm.

[0115] The procedure to obtain the powder was the same as in Example 1, except that rolls E and F were used instead of rolls A and B, which were used to create the cracks.

[0116] The state of debris adhesion to roll F after the crack formation process is evaluated using the method described above. As a result, it is expected that there will be a large amount of debris adhesion, making it difficult to efficiently obtain the debris.

[0117] In the table below, the abbreviations have the following meanings. "Cholesteric resin layer": A layer of cured liquid crystal composition. "Al film": Deposited aluminum film

[0118] [Table 1]

[0119] In the manufacturing method of Comparative Example 1, where a protrusion higher than 1.5Tμm is formed on the surface of the roll used to create cracks, a large amount of peeling material adheres to the roll, and peeling material cannot be efficiently obtained. On the other hand, in the manufacturing method of the Example, which uses a roll with a protrusion height of 1.1Tμm or more and 1.5Tμm or less, no peeling material adheres to the roll, and peeling material can be efficiently produced. Here, the thickness of the thin film is denoted as T. [Explanation of Symbols]

[0120] 10. Multi-layer film 11 Thin film 12 Base material layer 100 Multi-layer film 100C crack 100C1 notches 100C2 notches 100Cd depth 100Ct tip 101 small pieces 110 Thin film 110T thickness 110U surface 120 Base material layer 120U surface 200 multi-layer film 200C crack 200Ct tip 201 Small piece 210 Thin film 220 Base material layer 220U surface 1110 rolls 1110T protrusion 1110T1 protrusion 1110T2 convex part 1110t peak 1110D recess 1111 End 1112 End 1115 roll 1115T protrusion 1115T1 convex part 1115T2 convex part 1115t peak 1115D recess 1116 End 1117 End 1120 Support member 1125 Support member

Claims

1. An apparatus comprising a roll positioned in contact with the thin-film side surface of a multilayer film comprising a substrate layer and an outermost thin film, wherein the roll is pressed against the thin-film side surface to form a crack in the thin film, The apparatus comprises a roll having a protrusion on its circumferential surface, the height of which is 1.1T μm or more and 1.5T μm or less, where T represents the thickness (μm) of the thin film.

2. The apparatus according to claim 1, further comprising a support member disposed on the surface on the base material layer side, which together with the rolls sandwiches and presses the multilayer film.

3. Step (1) of forming a crack in a multilayer film comprising a base layer and an outermost thin film, the crack being such that it divides the thin film into small pieces of the same shape when viewed in the thickness direction, and the crack reaching a position deeper than the surface of the base layer on the thin film side, The process includes (2) peeling off small pieces of the thin film from the substrate layer of the multilayer film in which the cracks have been formed, in order to obtain a powder containing the small pieces of the thin film. The above step (1) includes a step (1a) of pressing the circumferential surface of the roll against the thin film side of the multilayer film, A method for manufacturing powder, wherein the roll has a protrusion on its circumferential surface, the height of which is 1.1T μm or more and 1.5T μm or less, where T represents the thickness (μm) of the thin film.

4. The method for producing powder according to claim 3, wherein the circumferential surface between the protrusions of the roll is flat.

5. The method for producing powder according to claim 3, wherein the thickness T of the thin film is 0.1 μm or more and 20 μm or less.

6. The method for producing powder according to claim 3, wherein in step (1a), the pressure applied to the circumferential surface of the roll is 0.5 MPa or more.

7. The method for producing powder according to claim 3, wherein the pressing in step (1a) is performed while the multilayer film is supported by a support member having a surface hardness of D40 or higher.

8. The method for producing powder according to claim 3, wherein the major axis of the small piece is 150 μm or less.

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