Resin Sheet

Abstract

The resin sheet of the present invention contains a heat-resistant resin as a main component, has no air permeability in the thickness direction, and has an air permeability A in the plane direction of at least one main surface of 1 mL / min or more. The air permeability A is a characteristic represented by the following air permeability, which is: a ring-shaped measurement area with an outer diameter of 47 mm and an inner diameter of 20 mm is set on the above-mentioned main surface, and the above-mentioned sheet is pressed against the above-mentioned smooth surface with a load of 654.5 gf in such a way that the above-mentioned main surface is in contact with the smooth surface of the member that does not have air permeability in the thickness direction in the entire above-mentioned measurement area, and the inside of the above-mentioned measurement area is depressurized by 15 kPa compared with the outside, and the air permeability between the surface and the smooth surface from the outside of the measurement area to the inside per minute. The resin sheet of the present invention can achieve stable use at high temperatures.

Description

Technical Field

[0001] The present invention relates to a resin sheet. Background Art

[0002] Resin sheets containing a heat-resistant resin as a main component (heat-resistant resin sheets) are known. Patent Document 1 discloses a sheet of polytetrafluoroethylene (hereinafter referred to as "PTFE"). Patent Document 2 discloses a sheet of polyimide. Heat-resistant resin sheets are assumed to be used at high temperatures.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent Application Laid-Open No. 3-197122

[0006] Patent Document 2: Japanese Patent Application Laid-Open No. 4-283246 Summary of the invention

[0007] Problem that the invention aims to solve

[0008] The heat-resistant resin sheet is used, for example, by being placed on an object. After being exposed to high temperatures, the heat-resistant resin sheet is sometimes peeled off from the state where it is placed on the object. When the heat-resistant resin sheet does not have air permeability in the thickness direction, bubbles mixed between the sheet and the object during placement may remain after placement, or it may be difficult to peel off the sheet from the state where it is closely attached to the object. In addition, the remaining bubbles may expand due to high temperatures, thereby adversely affecting the object. When the heat-resistant resin sheet has air permeability in the thickness direction, the above-mentioned problems are not easily generated, but it is easy to shrink and deform when used at high temperatures.

[0009] An object of the present invention is to provide a resin sheet which contains a heat-resistant resin as a main component and can be used stably at high temperatures.

[0010] Solutions for solving problems

[0011] The present invention provides a resin sheet comprising a heat-resistant resin as a main component.

[0012] The resin sheet has no air permeability in the thickness direction, and an air permeability A in the surface direction of at least one main surface is 1 mL / min or more.

[0013] The air permeability A is a property represented by the following air permeability, wherein the air permeability is:

[0014] A ring-shaped measurement area with an outer diameter of 47 mm and an inner diameter of 20 mm was set on the aforementioned main surface.

[0015] The sheet is pressed against the smooth surface with a load of 654.5 gf so that the main surface contacts the smooth surface of the member having no air permeability in the thickness direction throughout the measurement area, and the pressure inside the measurement area is reduced by 15 kPa compared with the pressure outside.

[0016] The amount of air permeating between the main surface and the smooth surface from the outside to the inside of the measurement area per minute.

[0017] Effects of the Invention

[0018] The resin sheet of the present invention does not have air permeability in the thickness direction. In other words, the resin sheet does not have pores or through holes that provide air permeability in the thickness direction. Therefore, shrinkage and deformation during use at high temperatures can be suppressed. On the other hand, the resin sheet of the present invention has an air permeability A in the surface direction on at least one main surface. Therefore, by using the main surface in a manner facing the object, the mixing of bubbles caused by the configuration can be suppressed, or the peelability from the state of being closely attached to the object can be improved. Therefore, the resin sheet of the present invention can achieve stable use at high temperatures. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a cross-sectional view schematically showing an example of the resin sheet of the present invention.

[0020] Figure 2 It is a plan view schematically showing the state of the main surface in one example of the resin sheet of the present invention.

[0021] Figure 3 This is a schematic diagram showing an example of a mode of using the resin sheet of the present invention.

[0022] Figure 4 This is a schematic diagram showing another example of the mode of using the resin sheet of the present invention.

[0023] Figure 5 It is a schematic diagram for explaining the evaluation method of the air permeability A in the plane direction of a resin sheet.

[0024] Figure 6 It is a schematic diagram for explaining the surface processing template used in the Example.

[0025] Figure 7 It is a graph showing the maximum height Rz and the air permeability A in the plane direction of the resin sheets produced in Examples and Comparative Examples.

[0026] Figure 8 It is a graph showing the arithmetic mean roughness Ra and the air permeability A in the surface direction of the resin sheets produced in Examples and Comparative Examples. DETAILED DESCRIPTION

[0027] Hereinafter, embodiments of the present invention will be described with reference to the drawings.

[0028] [Resin sheet]

[0029] An example of the resin sheet of the present invention is shown in Figure 1 . Figure 1 The resin sheet 1 shown contains a heat-resistant resin as a main component. The resin sheet 1 is a single layer. The resin sheet 1 has heat resistance derived from the heat-resistant resin. In this specification, "main component" refers to the component with the largest content. The content of the main component is, for example, 50% by weight or more, and can be 60% by weight or more, 70% by weight or more, 80% by weight or more, and further 90% by weight or more. The resin sheet 1 can be formed of a heat-resistant resin.

[0030] The resin sheet 1 does not have air permeability in the thickness direction. In this specification, "does not have air permeability in the thickness direction" means that the air permeability (Gurley air permeability) obtained by the air permeability measurement B method (Gurley method) specified in Japanese Industrial Standard (hereinafter referred to as "JIS") L1096: 2010 is expressed as an air permeability in the thickness direction exceeding 10,000 seconds / 100mL. The resin sheet 1 usually does not have pores and / or through holes connecting the two main surfaces 2A and 2B of the sheet. The resin sheet 1 is typically a non-porous sheet made of a non-porous base material.

[0031] The air permeability A in the surface direction of one main surface 2A of the resin sheet 1 is 1 mL / min or more. The air permeability A may be 2 mL / min or more, 5 mL / min or more, 9 mL / min or more, 15 mL / min or more, or 30 mL / min or more. The upper limit of the air permeability A is, for example, 100 mL / min or less. The other main surface 2B of the resin sheet 1 may or may not have an air permeability A in the surface direction within the above-mentioned ranges. In the resin sheet of the present invention, the air permeability A in the surface direction of at least one main surface is within the above-mentioned ranges.

[0032] The air permeability A is a property represented by the air permeability that is the amount of air that permeates between the main surface and the smooth surface from the outside of the measurement area to the inside of the measurement area per minute when a ring-shaped measurement area with an outer diameter of 47 mm and an inner diameter of 20 mm is set on the main surface, the main surface is in contact with the smooth surface in the entire measurement area, and the resin sheet 1 is pressed against the smooth surface with a load of 654.5 gf, and the pressure inside the measurement area is reduced by 15 kPa compared with the pressure outside. The smooth surface on which the resin sheet 1 is pressed is, for example, a surface having an arithmetic mean roughness Ra (hereinafter referred to as "arithmetic mean roughness Ra") of 0.1 μm or less as specified in JIS B0601:2001. In addition, the smooth surface is a surface of a member that does not have air permeability in the thickness direction, and is a surface that does not deform when evaluating the air permeability A and is not bonded or adhered to the sheet to be evaluated. The smooth surface is, for example, a surface of a resin plate or a metal plate that has a sufficient thickness to not deform when evaluating the air permeability A. Examples of the resin plate include an acrylic plate and a polycarbonate plate. Examples of the metal plate include a stainless steel plate. The load is sufficient for evaluating the air permeability A without excessively deforming the surface shape of the main surface.

[0033] It should be noted that the air permeability A in the plane direction of each main surface of the resin sheet manufactured by a common forming technique such as melt forming and cast forming is usually 0 mL / min. In addition, as shown in the embodiments described below, when the surface roughness of the main surface, such as the arithmetic mean roughness Ra, is large, the air permeability A in the plane direction of the main surface will not automatically become more than 1 mL / min.

[0034] The heat-resistant resin contained in the resin sheet 1 is typically a resin having a melting point of 150° C. or higher. The melting point of the heat-resistant resin may be 160° C. or higher, 200° C. or higher, or 300° C. or higher. Examples of the heat-resistant resin include fluororesins, polyimides, polyamideimides, and polyphenylene sulfide.

[0035] The heat-resistant resin is preferably a fluororesin. In other words, the resin sheet 1 is preferably a fluororesin sheet. Fluororesins generally have high heat resistance and peelability. In addition, fluororesins are softer than other heat-resistant resins such as polyimide. Therefore, the air permeability A based on the surface processing described later can be more reliably and effectively implemented.

[0036] Examples of fluororesins are PTFE, tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), tetrafluoroethylene-hexafluoropropylene copolymer (FEP), tetrafluoroethylene-ethylene copolymer (ETFE). Fluororesin is preferably PTFE. PTFE has particularly excellent heat resistance and peelability. Fluororesin sheet 1 may not contain components other than fluororesin, or may substantially not contain components other than fluororesin. In this specification, "substantially not containing" means that the content is less than 0.1% by weight, preferably less than 0.01% by weight.

[0037] The surface roughness of the main surface 2A having an air permeability A of 1 mL / min or more is represented by the maximum height Rz (hereinafter, described as "maximum height Rz") specified in JIS B0601:2001, for example, 30 μm or less, 25 μm or less, 23 μm or less, 20 μm or less, 18 μm or less, 15 μm or less, 13 μm or less, 10 μm or less, 9 μm or less, and further 8 μm or less. The lower limit of the maximum height Rz is, for example, 2 μm or more. The other main surface 2B may have a maximum height Rz within the above ranges.

[0038] The surface roughness of the main surface 2A having an air permeability A of 1 mL / min or more is represented by an arithmetic mean roughness Ra, which is, for example, 6 μm or less, and may be 5 μm or less, 4 μm or less, 3 μm or less, or 2 μm or less. The lower limit of the arithmetic mean roughness Ra is, for example, 0.3 μm or more. The other main surface 2B may have an arithmetic mean roughness Ra within the above ranges.

[0039] The main surface 2A may have a groove portion consisting of one or more grooves. The groove portion may become a permeation path for air passing through between the main surface 2A and the smooth surface when the resin sheet 1 is pressed against the smooth surface. The groove portion may have at least one groove connected to the periphery of the resin sheet 1 at one end or both ends. The groove portion may have at least one groove connected to the periphery of the resin sheet 1 at both ends. In this case, the effect of achieving a greater air permeability A and / or the effect of improving the uniformity of the air permeability A of the resin sheet 1 can be obtained. In the case where the shape of the main surface of the resin sheet 1 is a polygon, the groove portion may have at least one groove connecting one side of the polygon and one or more sides different from the side. The groove portion may be unfolded over the entire main surface 2A. In this case, the uniformity of the air permeability A of the resin sheet 1 can be improved. The width of each groove constituting the groove portion is, for example, 10 to 200 μm, and may be 20 to 50 μm. The depth of each groove constituting the groove portion is, for example, 2 to 30 μm, and may be 10 to 30 μm. Among them, for a certain groove, the width and / or depth may not be constant throughout the groove. In addition, the width and depth of each groove constituting the groove portion may be different, and the groove portion may have a plurality of grooves with different widths and / or depths. The groove constituting the groove portion may extend in a straight line on the main surface 2A, or may extend in a non-straight line, such as a curved line. The other main surface 2B may also have the above-mentioned groove portion.

[0040] The groove portion may have grooves arranged in a grid pattern on the main surface 2A and / or the main surface 2B. Figure 2 An example of the resin sheet 1 having the groove portion on the main surface 2A is shown in FIG. Figure 2The main surface 2A of the resin sheet 1 has a groove portion 4 composed of a plurality of grooves 3 arranged in a square lattice. Each groove 3 is connected to the periphery 5 of the resin sheet 1 at its two ends. The groove portion 4 is extended over the entire main surface 2A. The lattice in which the grooves 3 are arranged is not limited to a square lattice. The grooves 3 may be arranged in various lattice shapes, such as a rectangular lattice, an oblique lattice, a hexagonal lattice, a diamond lattice, a central rectangular lattice, etc. Among the grooves 3 arranged in a lattice shape, the pitch P1, which is the distance between the center lines of adjacent grooves 3, is, for example, 50 to 1000 μm, and may be 200 to 1000 μm.

[0041] The thickness of the resin sheet 1 is, for example, 10 to 500 μm, 20 to 300 μm, 30 to 200 μm, or further 50 to 100 μm.

[0042] The shape of the resin sheet 1 is, for example, a polygon including a square and a rectangle, a circle, an ellipse, and a strip. However, the shape of the resin sheet 1 is not limited to the above examples. The polygonal, circular, and elliptical resin sheets 1 can be circulated in the form of a sheet, and the strip-shaped resin sheet 1 can be circulated in the form of a winding body (roll) wound on a winding core. The width of the strip-shaped resin sheet 1 and the width of the winding body formed by winding the strip-shaped resin sheet 1 can be freely set.

[0043] Figure 1 The resin sheet 1 is a single layer. However, other layers may be arranged on the main surface 2A and / or the main surface 2B of the resin sheet 1 .

[0044] [Method for producing resin sheet]

[0045] The resin sheet 1 can be produced, for example, by the following method.

[0046] First, a precursor sheet containing a heat-resistant resin as a main component is prepared. The precursor sheet can be produced by a common sheet forming method such as melt forming and cast forming.

[0047] As an example, a method for producing a precursor sheet (PTFE precursor sheet) containing PTFE as a main component will be described.

[0048] First, PTFE powder (molding powder) is introduced into a mold, and a predetermined pressure is applied to the powder in the mold for a predetermined time to perform preforming. Preforming can be performed at room temperature. For the shape of the internal space of the mold, in order to achieve the cutting based on a cutting lathe described later, a cylindrical shape is preferably used. In this case, a cylindrical preform and a PTFE block can be obtained. Then, the preform is taken out of the mold, and calcined for a predetermined time at a temperature above the melting point (327°C) of PTFE to obtain a PTFE block. Then, the PTFE block is cut into a predetermined thickness to obtain a PTFE precursor sheet as a skive sheet. For a cylindrical PTFE block, a cutting lathe that continuously cuts the surface while the block is rotated can be used. Therefore, a PTFE precursor sheet can be effectively obtained. In addition, using a cutting lathe, the thickness of the formed PTFE precursor sheet is relatively easy to control, and a strip-shaped PTFE precursor sheet can also be obtained.

[0049] The PTFE precursor sheet can be produced by the following method.

[0050] First, prepare the substrate sheet to be coated with PTFE dispersion on the surface. The substrate sheet is for example made of resin, metal, paper and their composite materials. The surface of the substrate sheet coated with PTFE dispersion can be subjected to a stripping process for making the PTFE sheet easy to peel off from the substrate sheet. Known methods can be applied in the stripping process. Then, a coating film of PTFE dispersion is formed on the surface of the substrate sheet. The coating of PTFE dispersion can use known various coating machines. It is also possible to form a PTFE sheet by being immersed in the surface coating of the substrate sheet. Then, the coating film formed is dried and calcined to form the PTFE sheet. Then, the PTFE sheet formed is peeled off from the substrate sheet to obtain a PTFE precursor sheet as a cast sheet. In the method, the thickness of the PTFE precursor sheet can be controlled by the coating thickness of the substrate sheet by the PTFE dispersion.

[0051] The method for producing the PTFE precursor sheet is not limited to the above example.

[0052] Next, at least one main surface of the precursor sheet is subjected to surface processing to impart air permeability A. During the surface processing, the main surface is given a surface shape that can become a passage for air between the smooth surface when pressed on the smooth surface. Examples of surface processing are: scratch processing, etching processing based on laser irradiation, etc., and a press processing in which a template having a specific surface shape on the pressing surface is pressed on the above-mentioned main surface and pressurized. It should be noted that in the case of a precursor sheet of a relatively soft resin such as a fluororesin, the template can also be pressed and pressurized on the main surface on the opposite side of the main surface to be surface processed. However, the method of surface processing is not limited to the above examples.

[0053] The scraping process can be performed, for example, by scraping the main surface using a scraping member. Examples of the scraping member are files, sandpaper, grindstones, steel wool, and sheets, disks, belts, etc. having a scraping surface formed by these members. However, the scraping member is not limited to the above examples.

[0054] The etching process can be performed by, for example, irradiation with active energy rays such as laser light or chemical etching using a mask such as a resist, etc. However, the etching process method is not limited to the above examples.

[0055] The template used in the press working is made of, for example, metal, resin, glass, or a composite material thereof. As the template, the above-mentioned scraping member may also be used. It should be noted that, for the formation of the resin sheet 1 having the groove portion 4 with the grooves 3 arranged in a grid on the main surface, a template having a surface shape complementary to the groove portion, for example, a surface shape in which linearly extending protrusions are arranged in a grid, may be used.

[0056] [Use of resin sheet]

[0057] An example of the use of the resin sheet 1 is shown in Figure 3 . Figure 3 In the embodiment, the resin sheet 1 is wound on a roll (roll) 11 in a state of being stacked with a film 12. The resin sheet 1 is used as a protective sheet for the film 12. By utilizing the air permeability A, for example, the mixing of bubbles when the resin sheet 1 is stacked on the film 12 and / or when it is rolled together with the film 12 can be suppressed. In addition, the unwinding from the roll 11 and / or the peeling of the resin sheet 1 after unwinding can be implemented more stably.

[0058] The film 12 is made of, for example, metal or resin. It should be noted that, for the resin film 12, exhaust gas is sometimes generated after being formed into a film. Exhaust gas is easily generated in, for example, the film 12 of polycarbonate, polystyrene and acrylic resin. The exhaust gas generated after winding remains between adjacent films 12 and may cause deformation, depression, etc. of the film 12. By stacking and winding the resin sheet 1 and the film 12, the exhaust gas generated after winding can be more reliably released to the outside. In addition, it is also conceivable to implement a degassing treatment in which the winding body 11 is heated so that the exhaust gas is released to the outside in advance.

[0059] Another example of the use of the resin sheet 1 is shown in Figure 4 . Figure 4In the embodiment, the resin sheet 1 is wound on a winding body (roll) 13 in a state of being laminated with an adhesive tape 16. The adhesive tape 16 is a laminate of a base film 14 and an adhesive layer 15. The resin sheet 1 is in contact with the adhesive layer 15. The surface of the resin sheet 1 in contact with the adhesive layer 15 is, for example, a main surface 2A having an air permeability A. The resin sheet 1 is used as a separator of the adhesive tape 16. By utilizing the air permeability A, for example, the mixing of bubbles when the resin sheet 1 is laminated on the adhesive tape 16 is suppressed. In addition, the peeling of the resin sheet 1 after being released from the winding body 13 can be implemented more stably.

[0060] The adhesive tape 16 is usually subjected to an aging treatment after being wound around the winding body 13. The aging treatment stabilizes the adhesiveness of the adhesive layer 15. At this time, outgassing may be generated from the adhesive layer 15. The outgassing may remain between adjacent adhesive tapes 16 and may cause deformation, depression, etc. of the adhesive layer 15. By stacking and winding the resin sheet 1 and the adhesive tape 16, the outgassing generated during the aging treatment can be more reliably discharged to the outside.

[0061] The application and method of using the resin sheet 1 are not limited to the above examples. For example, the resin sheet 1 can be used for various applications exposed to high temperatures. In addition, the resin sheet 1 can be placed on a stage or a table for use.

[0062] Example

[0063] The present invention will be described in more detail by way of examples. The present invention is not limited to the following examples.

[0064] First, the evaluation method of the characteristics of the resin sheets of Examples and Comparative Examples will be described.

[0065] [Air permeability in thickness direction]

[0066] The air permeability in the thickness direction of the resin sheet (Gurley air permeability) is determined in accordance with the air permeability measurement method B (Gurley type method) specified in JIS L1096:2010.

[0067] [Air permeability in the surface direction A]

[0068] The air permeability A of the main surface (evaluation surface) of the resin sheet was determined as follows using a measuring jig. Figure 5 The evaluation method of the air permeability A is described.

[0069] As a measuring jig, a ring-shaped acrylic resin plate 52 (thickness 2.0 mm) with an outer diameter of 47 mm and an inner diameter of 20 mm, a disk-shaped silicone rubber sheet 53 (thickness 2.0 mm and weight 4.5 g) with a diameter of 47 mm, and a cylindrical weight 54 (made of stainless steel, weight 650 g) with a diameter of 47 mm were prepared. In addition, the resin sheet was cut into a circle with a diameter of 47 mm, which was used as a test piece 51. The arithmetic mean roughness Ra of the surface (smooth surface) of the acrylic resin plate 52 in contact with the test piece 51 was 0.03 μm. The acrylic resin plate 52 does not have air permeability in the thickness direction.

[0070] Next, the test piece 51, the silicone rubber sheet 53 and the weight 54 are sequentially arranged on the acrylic resin plate 52 in such a manner that the outer peripheries thereof coincide with each other. The test piece 51 is arranged in such a manner that the evaluation surface contacts the acrylic resin plate 52. The silicone rubber sheet 53 is arranged in order to apply the loads brought by the weight 54 and the rubber sheet 53 itself to the test piece 51 as evenly as possible. Next, the opening 55 of the through hole 56 located in the center of the acrylic resin plate 52 (the opening 55 on the surface opposite to the test piece 51 side) is connected to the suction tube connected to the pump. A pressure gauge is arranged at the connection portion of the suction tube with the opening 55, and a flow meter is arranged between the pump and the opening 55 of the suction tube. Next, the pump is operated to implement a decompression test in which the pressure in the through hole 56 is maintained at a decompression state 15 kPa lower than the external pressure (atmospheric pressure). Then, the flow rate of air per minute flowing in the suction tube during the test is measured using a flow meter, and the obtained value is used as the air permeability A of the evaluation surface of the resin sheet. The test was conducted at room temperature (25° C.) The measured value after the flow rate of air flowing through the suction tube stabilized after the start of the decompression test was defined as the air permeability A in the plane direction.

[0071] [Surface roughness (Rz and Ra)]

[0072] The surface roughness (maximum height Rz and arithmetic mean roughness Ra) of the evaluation surface of the resin sheet was evaluated using a surface property measuring device (SURFCOM1400D manufactured by Tokyo Seimitsu) capable of performing measurement in accordance with the provisions of JIS B0601:2001.

[0073] (Comparative Example 1)

[0074] PTFE powder (DAIKIN INDUSTRIES, Ltd., Polyflon PTFEM-12) was introduced into a cylindrical mold and preformed under the conditions of temperature 23°C, pressure 60 MPa and pressure application time 1 hour. Then, the preformed product was taken out from the mold and calcined at 375°C for 3 hours to obtain a cylindrical PTFE block with a height of 300 mm and an outer diameter of 200 mm. Then, the obtained PTFE block was cut using a cutting lathe to produce a PTFE sheet with a thickness of 50 μm, which was used as the resin sheet of Comparative Example 1.

[0075] (Examples 1 to 3)

[0076] A stainless steel sheet having a surface shape in which linearly extending protrusions 61 are arranged in a square grid is prepared as a template. The template has the above-mentioned surface shape on the entire pressing surface 62 (see Figure 6 ). The width of the protrusion 61 is set to 0.02 to 0.03 mm. The pitch P2, which is the distance between the center lines of adjacent protrusions 61, is set to 0.26 mm. The height of the protrusion 61 from the pressing surface 62 is set to 0.10 mm. The extension direction of each protrusion 61 is set to a direction that intersects with one side of the template at 45 degrees. Next, the above-mentioned template is arranged on one main surface of the resin sheet produced in Comparative Example 1, and a press process of pressing the template on the above-mentioned one main surface is performed at 25°C. The template is arranged in a manner that covers the entire sheet when viewed from a direction perpendicular to the press surface. In addition, the template is arranged in a manner that the pressing surface 62 contacts the above-mentioned one main surface, and the direction in which each protrusion 61 extends intersects with one side of the resin sheet at 45 degrees. The pressure (pressing pressure) of pressing the template is set to 11.2 MPa (Example 1), 33.4 MPa (Example 2) and 55.6 MPa (Example 3). The arrangement surface of the template during the press process is used as the evaluation surface of the produced resin sheet.

[0077] (Examples 4, 5 and Comparative Example 2)

[0078] The same operation as in Examples 1 to 3 was performed except that the width of the protrusion 61 was changed to 0.01 to 0.02 mm, the pitch P2 was changed to 0.13 mm, and the height of the protrusion 61 from the pressing surface 62 was changed to 0.04 mm, to obtain resin sheets of Comparative Example 2, Example 4, and Example 5 (with pressurizing pressures of 11.2 MPa, 33.4 MPa, and 55.6 MPa, respectively). The arrangement surface of the template during the press processing was used as the evaluation surface of the produced resin sheet.

[0079] The evaluation results of the resin sheet are shown in Table 1 below.

[0080] [Table 1]

[0081]

[0082] The graphs of the evaluation surfaces of Examples 1 to 5 and Comparative Examples 1 and 2 are shown with the maximum height Rz as the horizontal axis and the air permeability A as the vertical axis. Figure 7 In addition, the graphs of the evaluation surfaces of Examples 1 to 5 and Comparative Examples 1 and 2 are shown with the arithmetic mean roughness Ra as the horizontal axis and the air permeability A as the vertical axis. Figure 8 .like Figure 7 , 8 As shown, it was confirmed that the air permeability A of the evaluation surface of the resin sheet is not a property automatically determined by the maximum height Rz and the arithmetic mean roughness Ra of the surface.

[0083] Industrial Applicability

[0084] The resin sheet of the present invention can be used in various applications that are exposed to high temperatures, for example.

Claims

1. A releasable resin sheet which is placed on an object and then heated to be peeled off from the object. The peelable resin sheet is a fluororesin sheet, The releasable resin sheet has no air permeability in the thickness direction, and the air permeability A in the plane direction of at least one main surface is 1 mL / min or more, The at least one main surface has a groove portion consisting of one or more grooves, The groove portion has at least one groove whose one end or both ends are connected to the periphery of the resin sheet, and the groove portion has the grooves arranged in a grid pattern on the at least one main surface. In the grooves arranged in a grid pattern, the distance between the center lines of adjacent grooves is 50 to 260 μm, wherein The air permeability A is a property represented by the following air permeability, where: A ring-shaped measurement area with an outer diameter of 47 mm and an inner diameter of 20 mm is set on the main surface. The sheet is pressed against the smooth surface with a load of 654.5 gf so that the main surface contacts the smooth surface of the member having no air permeability in the thickness direction throughout the measurement area, and the pressure inside the measurement area is reduced by 15 kPa compared with the pressure outside. The amount of air permeating between the main surface and the smooth surface from the outside to the inside of the measurement area per minute.

2. The removable resin sheet according to claim 1, wherein The surface roughness of the main surface is represented by the arithmetic mean roughness Ra specified in JIS B0601:2001 and is 10 μm or less.

3. The removable resin sheet according to claim 1, wherein The fluororesin is polytetrafluoroethylene.

Images