JP2015188576A - Method for manufacturing flake - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing flakes.SOLUTION: Flakes including thermoplastic resin P1 and having desired shape and thickness are manufactured by: to a lamination structure 10 where at least an A layer 11 including the thermoplastic resin P1 having a melting point Tm1, and a B layer 12 including thermoplastic resin P2 having a glass transition temperature Tg2 are laminated, heating a metallic mold 20 having a recessed shape on the surface to a temperature of Tm1 or less and Tg2 or more, and pressing to an A layer side of the lamination structure so as to divide the A layer; forming a recess communicated with the division part of the A layer on the B layer; and removing the B layer from the A layer.

Description

  The present invention relates to a method for manufacturing a flake. The flakes obtained by this production method can be used, for example, as a medical material, as a sheet (for example, a so-called “nano-adhesive plaster”) for the purpose of protecting wounds.

  Examples of the method for producing a thin piece whose thickness and shape are controlled with high accuracy include cutting and pulverizing a thin film. When a thin film having a thickness of several μm or less is cut, since it is difficult to hold the thin film, it is generally cut in a state of being bonded to another resin or the like serving as a base material. In addition, when the thickness of the thin film is about 10 μm or more and the shape control is not very accurate, the thin film can be handled as a single film and pulverized or punched.

  Patent Document 1 discloses a method of patterning a surface layer by pressing a mold against a laminate made of a thermoplastic resin and penetrating the surface layer with a mold convex portion. The surface layer is ruptured by a mold having recesses that are approximately triangular, approximately square, approximately hexagonal, circle, ellipse, etc., and is formed into a pattern such as approximately triangle, approximately square, approximately hexagon, circle, ellipse on the base. A method for forming a surface layer is disclosed.

  Further, in Patent Document 2, as a method for drilling a laminate, the second member side of the laminate having the first member and the second member is used at a temperature higher than the melting point or softening point of the second member. And the method of inserting the punch which is higher than melting | fusing point or softening point of a 1st member, and selectively removing a 2nd member is disclosed.

  Patent Document 3 discloses a method for forming a through-hole by pressurizing between a mold and an opposing substrate at a temperature higher than the flow starting temperature of the thermoplastic resin thin film as a method for drilling the thermoplastic resin thin film. ing.

JP 2006-159899 A JP 2002-26362 A JP 2006-142711 A

  When a thin film with a thickness of several μm or less is cut in a state of being bonded to another resin as a base material, it is difficult to cut only the thin film, and another resin as a base material is cut or half-cut. Therefore, chips generated from the base resin may be mixed. Moreover, since a cutting tool (a blade, a laser, etc.) was put in order to process a thin piece into a desired shape, there existed a problem that productivity was low. In addition, the physical pulverization has a problem that it is difficult to control the shape of the flakes with high accuracy, and it has been difficult to apply to very thin flakes having a thickness of several μm or less. Also, the punching process is difficult to apply to very thin flakes having a thickness of several μm or less that are likely to generate burrs on the end face of the punched portion.

  Furthermore, with the imprint technique disclosed in Patent Document 1, it is possible to form a desired shape on the surface layer, but it is difficult to separate the surface layer from the base. Moreover, even if it can be separated, it is difficult to produce a flake with few burrs because both the surface layer and the base portion are deformed when the surface layer is formed. The reason is that the resin deformation is governed by viscoelastic properties and may not be suitable for plastic deformation that divides a thin piece.

  The drilling method disclosed in Patent Document 2 is a drilling method, not the manufacture of a flake. Even if it is possible to hold the flakes made of the second member inside the punch by making the processing tip of the punch hollow, it is easy to collect the flakes held inside the punch in this way. In addition, the occurrence of burr on the cut surface of the thin piece may not be suppressed.

  Moreover, the drilling method currently disclosed by patent document 3 is a drilling method, Comprising: It is not a manufacturing method of a thin piece thing. Since it is a punched thermoplastic resin thin film, it is easy to peel off from the opposing base material, but the mold is changed from the punching method disclosed in Patent Document 3, and the thermoplastic thin piece on the opposing base material Even if the material is divided, it may be difficult to recover the thermoplastic flakes separated from the opposing substrate.

In order to solve the above-described problems, the present invention provides the following method for producing a flake.
(1) It has a concave shape on the surface with respect to a laminated structure in which an A layer containing a thermoplastic resin P1 having a melting point Tm1 and a B layer containing a thermoplastic resin P2 having a glass transition temperature Tg2 are laminated. The mold is heated to a temperature of Tm1 or higher and Tg2 or higher, and pressed against the A layer side of the laminated structure, thereby dividing the A layer and forming a recess in the B layer that communicates with the divided portion of the A layer. Then, the B layer is removed from the A layer, and a thin piece containing the thermoplastic resin P1 is obtained.
(2) The method for producing a flake according to (1), wherein the method of removing the B layer from the A layer is a method of dissolving and removing the B layer.
(3) The method for producing a flake according to (1) or (2), wherein a difference (Tm1−Tg2) between the melting point Tm1 and the glass transition temperature Tg2 is −30 to + 60 ° C.
(4) The method for producing a flake according to any one of (1) to (3), wherein the thermoplastic resin P1 is at least one selected from the group consisting of polyethylene, polypropylene, and polylactic acid.
(5) The thin piece according to any one of (1) to (4), wherein the thermoplastic resin P2 is at least one selected from the group consisting of polymethyl methacrylate, polycarbonate, and polyvinyl alcohol. Production method.

The present invention also provides the following flakes.
(6) A thin piece obtained by the production method according to any one of (1) to (5).
(7) The thin piece object according to (6), wherein the area of the thin piece object is 0.005 to ¹ mm ² .
(8) The thin piece according to (6) or (7), wherein the thickness of the thin piece is 0.01 to 10 μm.

  According to the present invention, a concave shape is formed on a laminated structure in which an A layer containing a thermoplastic resin P1 having a melting point Tm1 and a B layer containing a thermoplastic resin P2 having a glass transition temperature Tg2 are laminated. The mold on the surface is heated to a temperature of Tm1 or higher and Tg2 or higher, and pressed against the A layer side of the laminated structure, thereby dividing the A layer and communicating with the B layer to the divided portion of the A layer. A flake having a desired shape and thickness including the thermoplastic resin P1 can be manufactured by forming the recess and then removing the B layer from the A layer.

It is the flowchart which showed an example of the embodiment concerning the manufacturing method of the thin piece of this invention. It is a perspective view which shows an example of the metal mold | die applied to the manufacturing method of this invention. It is sectional drawing which shows an example of the metal mold | die applied to the manufacturing method of this invention. It is a cross-sectional schematic diagram which shows an example of the apparatus which implement | achieves the manufacturing method of the flakes of this invention. It is a cross-sectional schematic diagram which shows an example of the apparatus which implement | achieves the manufacturing method of the flakes of this invention.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a flowchart showing an example of an embodiment according to the method for manufacturing a flake of the present invention. FIG. 2 is a perspective view showing an example of a mold applied to the manufacturing method of the present invention.

  First, as shown in FIG. 1A, a laminated structure 10 in which an A layer 11 and a B layer 12 are laminated, and a mold 20 in which an independent concave shape is arranged on the surface are prepared. The A layer 11 includes a thermoplastic resin P1 having a melting point Tm1, and the B layer 12 includes a thermoplastic resin P2 having a glass transition temperature Tg2.

  Here, as a ratio of each thermoplastic resin contained in each layer, it is preferable to contain 60% by mass or more of the thermoplastic resin when each layer is 100% by mass. Furthermore, it is more preferable to contain 80 mass% or more. In addition to the thermoplastic resin P1 or the thermoplastic resin P2, each layer may contain an additive or a coating component for imparting moldability and releasability.

  A laminated structure refers to a structure in which two or more layers containing different components are laminated. In addition, the continuous structure film conveyed by roll to roll may be sufficient as a laminated structure, and a single wafer sheet may be sufficient as it.

The flakes are those having a thickness d of 10 μm or less and an area S of S ≧ 30d ² . As for the area S of the thin piece, when it is difficult to measure the actual area, the radius S1 of the maximum circle inscribed and the radius r2 of the minimum circle circumscribed with respect to the shape observed from the surface of the thin piece S = Assume that 2 × r1 × r2 is calculated.

  The glass transition temperature is a method according to the method described in JIS K 7244 (2007). The sample dynamic amplitude speed (drive frequency) is 1 Hz, the tensile mode, the distance between chucks is 5 mm, and the heating rate is 2 ° C./min. This is the temperature at which tan δ is maximized when the temperature dependence (temperature dispersion) is formulated.

  Further, the melting point here is a melting point Tm in a temperature raising process (temperature rising rate: 20 ° C./min) obtained by differential scanning calorimetry (hereinafter abbreviated as DSC), as described above. In accordance with JIS K 7121 (1999), heated from 25 ° C. to 300 ° C. at a heating rate of 20 ° C./min (1stRUN), held in that state for 5 minutes, and then rapidly cooled to 25 ° C. or lower, The temperature is raised from the room temperature to 300 ° C. at a rate of temperature increase of 20 ° C./min, and the melting point of the resin is determined by the peak top temperature in the 2ndRun crystal melting peak.

  The dent shape is an independent dent shape provided on the mold surface. The recess shape may be any shape as long as it is an independent recess shape provided on the mold surface.

  For example, examples of the shape of the recess seen from the mold surface include a circle, a triangle, a square, a hexagon, and similar shapes. If the dents are independent, a part of the wall surrounding the dents may be common between adjacent dents (for example, a shape as shown in FIG. 2 may be used). This is the case, for example, where a depression is formed by a cross-girder-like or honeycomb-like wall.

  In the present invention, the mold 20 having the concave shape 21 on the surface is heated. Heating is performed so that the mold has a temperature range of Tm1 or more and Tg2 or more. Heating may be performed in a state where the mold and the laminated structure are in contact with each other. By keeping the contact, the planarity of the laminated structure can be maintained in a good state.

  Next, as shown in FIG. 1 (b), the mold 20 is pressed and pressed so that the wall portion 22 constituting the concave shape contacts the surface of the layer A 11 of the laminated structure 10 in a heated state. Hit it. If the wall portion 22 constituting the concave shape has an appropriate height by being pressurized, the wall portion 22 constituting the concave shape penetrates the A layer 11 and penetrates to the B layer 12.

  The required pressure and pressurization time at this time depend on the material of the film, the transfer shape, particularly the aspect ratio of the unevenness, the preferable range of the pressing pressure is 0.5 to 5 MPa, and the preferable range of the molding time is 0. 01-180 seconds.

  A more preferable range of the pressing pressure is 1 to 5 MPa. A more preferable range of the molding time is 1 to 60 seconds.

  Further, the mold 20 may be pressed against the laminated structure 10 by position control. That is, the mold 20 may be moved to a preset position and pressed against the laminated structure 10. The preset position is a position where the wall surface constituting the concave shape of the mold can come into contact with the surface of the A layer without any gap.

  Note that, after pressurization, the contact state between the mold 20 and the laminated structure 10 may be maintained by removing the pressure while maintaining the position of the mold.

  Next, as shown in FIG.1 (c), a metal mold | die is cooled, maintaining the state which pressurized or contacted. Cooling is preferably performed to a glass transition temperature Tg2 or lower of the thermoplastic resin P2 constituting the B layer. Cooling to Tg2 or less is preferable because the resin deformation after the mold 20 is peeled from the laminated structure 10 can be suppressed, and a thin piece shape can be formed with high accuracy.

  Next, as shown in FIG. 1D, the laminated structure 10 is peeled from the mold 20. In peeling, the mold and the laminated structure are moved away from each other in the direction perpendicular to the surface of the laminated structure. In the case where the laminated structure is a continuous film, it is preferable to continuously apply a tension in the direction perpendicular to the surface of the laminated structure so that the linear peeling position moves continuously. .

  The removal of the B layer from the A layer 11 may be performed in communication therewith, or may be temporarily held while the divided A layer is supported by the B layer. In this case, until the B layer is removed, the film can be handled as a highly rigid film, which is preferable because workability is good.

  Next, the B layer 12 is removed from the A layer 11. Examples of the method for removing the B layer 12 include peeling and dissolution removal of the B layer, but dissolution removal of the B layer 12 is preferable as shown in FIG. This is because the A layer is divided into flakes, so if it is dissolved and removed, the B layer can be removed from the A layer at once. However, it is difficult to remove the B layer at once by separation such as peeling. This is because there are cases. For dissolution and removal, it is preferable to use a solvent in which the B layer is soluble and does not dissolve the A layer.

  In this way, it is possible to produce flakes. Here, when the B layer is dissolved and removed, the flakes are dispersed in the solvent as shown in FIG. The flakes may be separated from the solvent by drying the solvent, filtering, or the like, but depending on the method of use, the flakes may be kept dispersed in the solvent. Here, when layer B is polyvinyl alcohol, water can be used as a solvent, which is a particularly preferable embodiment.

  By performing the above-described steps described with reference to FIG. 1, the A layer 11 becomes a thin piece whose shape is controlled with high accuracy. By the above manufacturing method, the A layer is in a molten state at the time of molding. Therefore, when the wall constituting the concave shape is pressed, the A layer causes plastic deformation with a behavior close to that of a viscous material, and the end face of the dividing portion is divided with few burrs. Is done. Further, when the wall constituting the dent shape is pushed in, the B layer causes viscoelastic deformation, and the wall constituting the dent shape can smoothly enter the inside of the B layer. A beautiful end face with few burrs can be formed even at the interface.

  In order to cause such compositional deformation of the A layer and viscoelastic deformation of the B layer, the temperature T for heating the mold having the concave shape on the surface is preferably Tm1 or more and Tg2 or more. The mold heating temperature T is preferably 5 to 60 ° C. higher than Tg2. If the difference between Tg2 and the heating temperature T of the mold is less than 5 ° C., a large force is required for the deformation of the B layer. Therefore, the residual film of the A layer is likely to remain between the B layer and the mold. It may be insufficient. Conversely, if the difference between Tg2 and the heating temperature T of the mold is greater than 60 ° C., the deformation of the B layer starts before the mold surface reaches the B layer, and the A layer tends to bite into the B layer deformed portion. Therefore, there are cases where burrs are likely to remain around the thinned A layer.

  In order to cause the compositional deformation of the A layer at an appropriate temperature T to cause such viscoelastic deformation in the B layer, the melting point Tm1 of the thermoplastic resin P1 contained in the A layer 11 and the thermoplasticity contained in the B layer. It is preferable that (Tm1−Tg2), which is a difference from the glass transition temperature Tg2 of the resin P2, is −30 to + 60 ° C. More preferably, it is −10 to 0 ° C.

  Further, the storage elastic modulus of the resin contained in the B layer at the temperature of the mold at the time of molding is 0.005 to 0.5 GPa, more preferably 0.01 to 0.1 GPa. The flatness of the interface of the B layer and the burr suppression of the end face of the A layer dividing portion can be further enhanced. If it is less than 0.005 GPa, the planarity of the interface between the A layer and the B layer is lowered, and the A layer may not be divided, or burrs may be easily generated on the end face of the sharing part. On the other hand, if it is higher than 0.5 GPa, it is difficult to deform in the B layer, and the wall constituting the hollow shape of the mold is not inserted to the back, which may make it difficult to manufacture a flake with a predetermined shape accuracy.

  In the present invention, since the mold having the concave shape on the surface is heated to a temperature of Tm1 or more and Tg2 or more, when Tm1 is lower than Tg2, the difference between the mold heating temperature T and Tm1 is calculated as follows. It can be larger than the difference between the mold heating temperature T and Tg2. In this case, even if the difference between the mold heating temperature T and Tg2 is small for the purpose of suppressing the deformation of the B layer, the difference between the mold heating temperature T and Tm1 is set to 15 to 80. It can be as large as ° C and is preferable. This is because when the mold heating temperature T is sufficiently higher than Tm1, the viscosity of the A layer is further reduced, and smooth molding can be performed.

  As the main component of the thermoplastic resin P1 constituting the A layer 11, specifically, polyolefin resins such as polyethylene, polystyrene, polypropylene, polyisobutylene, polybutene, and polymethylpentene have good mold releasability. Preferably used. In addition, biodegradable resins such as polylactic acid, polycaprolactone, and polybutylene succinate are also preferable. These may be used alone or in a mixture. That is, the thermoplastic resin P1 may be at least one selected from the group consisting of polyethylene, polypropylene, and polylactic acid. In addition, a main component means the component which occupies 50 mass% or more when the whole resin which comprises A layer is 100 mass%. In addition, 50 mass% or more is preferable and, as for the main component, 80 mass% or more is more preferable.

  Specific examples of the main component of the thermoplastic resin P2 constituting the B layer 12 include polyester resins such as polyethylene terephthalate, polyethylene-2,6-naphthalate, polypropylene terephthalate, polybutylene terephthalate, polyethylene, polystyrene, polypropylene, poly Polyolefin resins such as isobutylene, polybutene, polymethylpentene, polyamide resins, polyimide resins, polyether resins, polyesteramide resins, polyetherester resins, acrylic resins, polyurethane resins, polycarbonate resins, or A polyvinyl chloride resin or the like is preferably used.

  Particularly preferred are polymethyl methacrylate, polycarbonate and polyvinyl alcohol. These may be used alone or in a mixture. That is, the thermoplastic resin P2 may be at least one selected from the group consisting of polymethyl methacrylate, polycarbonate, and polyvinyl alcohol. In addition, a main component means the component which occupies 50 mass% or more when the whole resin which comprises B layer is 100 mass%. In addition, 50 mass% or more is preferable and, as for the main component, 80 mass% or more is more preferable.

  The A layer and the B layer may be a layer made of the above-mentioned resin alone, or may be a laminated body made of a plurality of resin layers. In this case, surface characteristics such as releasability and friction resistance can be imparted as compared with a single layer. Thus, even when it is set as the laminated body which consists of a some resin layer, in each layer of A layer and B layer, the main thermoplastic resin component should just satisfy the above-mentioned requirements.

  Moreover, as a manufacturing method of A layer and B layer, it is good to form a thermoplastic resin into a film by melt extrusion. When a release layer, an adhesive layer, or the like is provided on the surface layer, a method of coextrusion and processing into a film may be used, but it may be provided by coating after film formation. Moreover, you may use the method of carrying out extrusion lamination of the surface layer raw material to the film produced with the single film. As the lamination of the A layer and the B layer, a method of laminating by pressing with a roll and a method of heat laminating with a heated roll or the like can be applied.

  Furthermore, various additives can be added to the film applied to the present invention at the time of polymerization or after polymerization. Examples of additives that can be added and blended include, for example, organic fine particles, inorganic fine particles, dispersants, dyes, fluorescent brighteners, antioxidants, weathering agents, antistatic agents, mold release agents, thickeners, Examples include plasticizers, pH adjusters, and salts. In particular, as a releasing agent, low surface tension carboxylic acids such as long chain carboxylic acids or long chain carboxylates and derivatives thereof, and low surface tension alcohols such as long chain alcohols and derivatives thereof, and modified silicone oils. It is preferable to add a small amount of a compound or the like during polymerization.

Moreover, as thickness of A layer applied to this invention, 0.01-10 micrometers is preferable, More preferably, it is 0.1-1 micrometer. The area of the thin piece is preferably 0.005 to ¹ mm ² .

  Such very thin flakes and small-area flakes may be difficult to produce by conventional methods such as cutting, half-cutting, crushing, and punching, and are particularly suitable as targets of the present method.

  Next, the mold shape will be described with reference to FIGS. FIG. 2 is a perspective view showing an example of a mold applied to the present invention, and FIGS. 3A and 3B are cross-sectional views showing an example of a mold applied to the present invention.

  On the outer surface of the mold 20, a recessed shape 21 is disposed at a predetermined position. As for the concave shape, only the same shape may be provided on the mold, or a plurality of different shapes may be provided.

  The width of the wall portion 22 constituting the concave shape is preferably a forward taper that becomes thicker from the mold surface to the deep part of the mold, and the taper angle is preferably 1 to 5 ° with respect to the direction perpendicular to the mold surface. When the taper is a reverse taper or when the angle is too small, it may be difficult to separate the mold from the laminate after dividing the A layer. Moreover, if the taper angle is too large, the cross-sectional shape in the thickness direction of the finally obtained thin piece may be crushed. In the case of a mortar-shaped depression that does not have a surface parallel to the mold surface at the bottom of the depression, the resulting flake will not have a certain thickness, but the bottom of the depression is parallel to the mold surface. The shape having a surface is preferable because the flakes basically have a uniform thickness. With regard to the wall width surrounding the depression, the wall portion is a portion for dividing the thin piece, and in order to efficiently manufacture the thin piece, the width of the divided portion is preferably narrow. However, if the wall width is too small, the mold strength is insufficient, so the wall width is preferably 1 to 10 μm. Further, the uppermost part of the wall (the outermost surface of the mold) may be sharpened like a knife edge as shown in FIGS. In this case, it is preferable because the pressure applied to the laminate can be increased when the mold is pressed against the A layer of the laminate, and the mold can smoothly enter the laminate. As shown in FIG. 3 (a), it is also preferable that the wall is bent halfway so that the top of the wall is sharpened in a knife edge shape and the bottom of the wall has a taper of 1 to 5 °. In this case, it is preferable that the wall height from the bottom portion to the bent portion is higher than the thickness of the finally obtained flake. Further, as shown in FIG. 3B, a simple shape in which the uppermost portion of the wall is sharpened on the knife edge may be used.

The concave shape arranged in the mold is preferably a regularly and closely packed arrangement such as a square arrangement or a hexagonal arrangement. The mold material is preferably a metal with high strength and thermal conductivity, such as nickel or steel, Stainless steel, copper and the like are preferred. Moreover, you may use what gave the outer surface the plating in order to improve workability.

  The method of creating each mold with a concave shape on the surface is a method of applying cutting, laser processing or electron beam processing directly on the metal surface, or applying cutting, laser processing or electron beam processing directly on the plating film formed on the metal surface. And a method of electroforming them. Also, after applying the resist on the substrate, forming the resist with a predetermined patterning by photolithography technique, etching the substrate to form a recess, and removing the resist to obtain the inverted pattern by electroforming Etc. A concave pattern can be obtained by applying anisotropic etching. As the substrate, a silicon substrate or the like can be applied in addition to the metal plate.

  Dividing the A layer means that the A layer is thinned and is not in contact with the B layer other than the boundary surface with the B layer, and the A layer is formed by the wall portion 22 constituting the recessed shape. The space penetrating from the surface of the surface to the other surface (the boundary surface with the B layer) is referred to as the A layer splitting portion. Moreover, the recessed part connected to a parting part means the recessed part of the B layer connected with the parting part formed in the A layer by the wall part 22 which comprises a recessed shape.

  The flakes of the present invention can be manufactured by a process through an apparatus as shown in FIGS. 4 and 5, for example. 4 and 5 are schematic cross-sectional views of a manufacturing apparatus for dividing the A layer of the film-like laminated structure formed by laminating the A layer and the B layer.

  In the example shown in FIG. 4, an unwinding unit 52 that pulls out a laminated structure 50 in which a film made of an A layer and a film made of a B layer are laminated in advance from an unwinding roll 51, and pressure that divides the A layer into a predetermined shape A press unit 54 for the transfer process, a peeling means 55 for peeling the laminated structure 50 attached to the mold 53 in the pressure transfer process from the mold 53, and a winding for winding the laminated structure 50 on the take-up roll 56 And a take-up unit 60. In a press unit 54 for a pressure transfer process for dividing the A layer into a predetermined shape, a heated mold 53 having a concave shape formed on the surface is pressed against the laminated structure 50 fed intermittently. Then, the A layer 50a of the laminated structure 50 is divided by cooling while maintaining the contact state. At the same time, the B layer 50b is formed with a recessed portion communicating with the dividing portion by a wall forming a recessed shape.

  The peeling means 55 consists of a pair of parallel arrangement rolls which hold | grip so that the laminated structure 50 may be held in S shape. One surface of the laminated structure 50 sent intermittently is thermoformed by the die 53 in the press unit 54, and after the thermoforming, the peeling means 55 is moved toward the upstream side, whereby the die 53 is moved. The laminated structure 50 that has been attached to is sequentially peeled off from the mold 53.

  In FIG. 4, 57 denotes a pressure plate, and 58 and 59 denote buffer means provided to smoothly perform intermittent conveyance in the mold 53 portion of the laminated structure 50. By such a process, it becomes possible to perform the division of the A layer and the formation of the recesses in the B layer intermittently with high productivity.

  In the example shown in FIG. 5, the films constituting the A layer 71 and the B layer 72 are drawn from the unwinding rolls 73 and 74, and the laminated structure 70 is formed by the laminating device 75. Thereafter, the laminated structure 70 is supplied by a heating roll 76 onto an endless belt-shaped mold 77 in which a concave shape is formed on the heated surface.

  A concave shape is formed on the outer surface of the mold 77 and is heated by the heating roll 76 immediately before coming into contact with the laminated structure 70. The laminated structure 70 that is continuously supplied is pressed against the surface of the die 77 where the concave shape is processed by the nip roll 78, and the A layer 71 of the laminated structure is divided. At the same time, a concave portion communicating with the dividing portion is formed in the B layer 72.

  Thereafter, the laminated structure 70 is conveyed to the outer surface position of the cooling roll 79 while being in close contact with the surface of the mold 77. The laminated structure 70 is cooled by heat conduction through the mold 77 by the cooling roll 79, and then peeled off from the mold 77 by the peeling roll 80 and taken up by the winding roll 81.

  Such a process makes it possible to thermoform a laminate having a flake on the surface of the B layer with high productivity.

  In order to extract a flake from the laminated structure in which the A layer is divided, it is necessary to remove the B layer. Examples of the method for removing the B layer include peeling and dissolution of the B layer. Here, in order to efficiently collect the A layer having a minute thickness and the outer shape, it is preferable to dissolve the B layer that can collect the flakes in a lump, instead of the peeling method of separating the flakes one by one. For dissolving the B layer, a method of immersing the laminated structure in a solvent in which the A layer is insoluble and the B layer is soluble can be employed. For example, when the main component of the thermoplastic resin constituting the B layer is polyvinyl alcohol, the B layer can be dissolved with water, which is particularly preferable. Further, the flakes after dissolving the B layer may be dried to remove the solvent used for dissolving the B layer, and may be dried flakes, but can also be handled in a state of being suspended in the solvent. In particular, when the main component of the thermoplastic resin constituting the B layer is polyvinyl alcohol, and the B layer is dissolved with water, the flakes can be handled in a floating state in water, which is preferable. Such a flake can be handled as it is as a wound covering sheet.

  Such a process makes it possible to produce flakes with high productivity.

[Application example]
In the above-described method for manufacturing a thin piece, a thin piece having a thickness of micron to nano size and an area of 1 mm ² or less can be designed with any shape and size, and the thin piece can be produced at low cost. Can be manufactured well. The flakes obtained by the production method of the present invention are suitably used for wound dressing sheets.

  For example, when a wound part is covered with a biodegradable thin piece as a nano-adhesive bandage, it is necessary to avoid mixing foreign materials as well as a thin piece to cover the wound part when the material and size of the thin piece are different. It is necessary to use a large number of overlapping objects, and as a result, the thickness of the coating may increase. Here, if it is a very thin flake material with a thickness of several μm or less as in the present invention, there are few large burrs, and it is a flake material with little mixing of different materials, different sizes, and different shaped flake materials, for example, By making the outer shape of the flakes circular or hexagonal, the overlap of the flakes can be reduced in such applications and the wound can be covered, and the covering thickness can be reduced. It becomes.

(Example 1)
(1) Laminated structure A 7 μm thick film containing a polymer (melting point Tm1 of 130 ° C.) mainly composed of polypropylene (hereinafter abbreviated as PP) in the A layer, and polycarbonate (hereinafter abbreviated as PC) as the B layer. A film having a thickness of 380 μm containing a polymer (glass transition temperature Tg2 of 145 ° C.) was used. One surface layer of the A layer has a 3 μm thick adhesive layer mainly composed of low density polyethylene. The adhesive layer of A layer was laminated so that it might adhere to the surface of B layer, and the laminated structure was comprised.

(2) Mold A mold having a square dent shape disposed on the entire surface was used. The dent was a square having a bottom of 90 μm on one side, a depth of 12 μm, and the taper of the wall constituting the dent was 2.75 °. A material in which the dents are squarely arranged at a pitch of 100 μm was used. The region where the dent shape is processed is a region of 50 mm (film width direction) × 50 mm (film transport direction). The mold was formed by machining the shape of a concave inversion (lattice groove having a groove entrance width of 10 μm and a depth of 12 μm), and then inverted by nickel electroforming.

(3) Molding apparatus and conditions The apparatus as shown in FIG. 4 was applied. The press unit is a mechanism that is pressurized by a hydraulic pump. Two pressurizing plates are attached inside the press unit, and are connected to a heating device and a cooling device, respectively. The mold is placed on the upper surface of the lower pressure plate. A peeling means for peeling the film attached to the mold is installed in the press unit.

  The mold temperature during molding was 150 ° C., and the pressure was 1 MPa over the entire surface. The pressurization time was 180 seconds. The mold temperature at the time of peeling was 60 ° C. The peeled film was sent out to the downstream winding device side and wound up.

(4) Observation Results The molded film was observed with a scanning electron microscope (Keyence VE-7800). The observation was performed from the surface of the laminate on the side of the A layer and the cross section. As a result of the observation, the A layer is divided into a square shape having a side of 90 μm, the thickness of the A layer after the division is about 9 μm, and the B layer has a recess that communicates with the divided portion of the A layer. The depth was about 3 μm.

(5) Separation of flakes An adhesive tape was applied to the A layer side of the formed film, and the resin flakes composed of the A layer were peeled from the B layer. After peeling, the adhesive tape and the peeled film were observed with a scanning electron microscope, and it was confirmed that the A layer was transferred to the adhesive tape as a thin piece.

The thin piece on the adhesive tape was observed with a scanning electron microscope (Keyence VE-7800). The area of the thin piece was measured by measuring the length and breadth of 10 pieces on the 300 times image obtained by observing the thin piece from the surface (surface parallel to the adhesive tape) with a scanning electron microscope, and the product of the average values. Calculated. The thin piece had a square shape with a side of 90 μm, and the area was 0.0081 mm ² . The thickness of the thin piece was 10 on a 1,000 times image obtained by observing a cross-section of the thin piece with the adhesive tape with a rotary microtome from the cross-section (surface perpendicular to the adhesive tape) with a scanning electron microscope. When the length of each piece was measured and the average value was taken, the thickness of the thin piece was 9 μm.

DESCRIPTION OF SYMBOLS 10: Laminated structure 11: A layer 12: B layer 20: Mold 21: Recessed shape 22: Wall part 50 which comprises a recessed shape 50: Laminated structure 50a: A layer 50b: B layer 51: Unwinding roll 52: Unwinding unit 53: Die 54: Press unit 55: Peeling means 56: Winding roll 57: Pressure plate 58, 59: Buffer means 60: Winding unit 70: Laminated structure 71: A layer 72: B layer 73 74: Unwinding roll 75: Laminating device 76: Heating roll 77: Mold 78: Nip roll 79: Cooling roll 80: Peeling roll 81: Winding roll

Claims (8)

  A mold having a concave shape on the surface of a laminated structure in which an A layer containing a thermoplastic resin P1 having a melting point Tm1 and a B layer containing a thermoplastic resin P2 having a glass transition temperature Tg2 are laminated. By heating to a temperature of Tm1 or more and Tg2 or more and pressing against the A layer side of the laminated structure, the A layer is divided, and a concave portion communicating with the divided portion of the A layer is formed in the B layer. A method for producing a thin piece, comprising removing the B layer from the A layer to obtain a thin piece containing the thermoplastic resin P1.   The method for producing a flake according to claim 1, wherein the method of removing the B layer from the A layer is a method of dissolving and removing the B layer.   The method for producing a flake according to claim 1 or 2, wherein a difference (Tm1-Tg2) between the melting point Tm1 and the glass transition temperature Tg2 is -30 to + 60 ° C.   The method for producing a flake according to any one of claims 1 to 3, wherein the thermoplastic resin P1 is at least one selected from the group consisting of polyethylene, polypropylene, and polylactic acid.   The method for producing a flake according to any one of claims 1 to 4, wherein the thermoplastic resin P2 is at least one selected from the group consisting of polymethyl methacrylate, polycarbonate, and polyvinyl alcohol. The thin piece obtained by the manufacturing method in any one of Claims 1-5. The thin piece object according to claim 6, wherein the area of the thin piece object is 0.005 to ¹ mm ² . The flake material according to claim 6 or 7, wherein the flake material has a thickness of 0.01 to 10 µm.