Release sheet

Abstract

This release sheet comprises a woven fabric base material and a resin layer on one surface of the woven fabric base material, wherein the resin layer has a release surface configured from a dip-bump pattern. At least part of the bumps of the dip-bump pattern are linearly contiguous. A different resin layer is provided on the other surface of the fabric base material, and this resin layer has a release surface configured from a dip-bump pattern.

Description

Release sheet

[0001] This disclosure relates to release sheets.

[0002] Composite materials containing fibers and resins are used in various technological fields. For example, Patent Document 1 proposes a method for manufacturing a conveyor belt using a sheet-like intermediate material made by coating a plain weave glass fiber fabric with fluororesin as the core sheet. In this manufacturing method, the sheet-like intermediate material is interposed between the unvulcanized belt molded body and the heating plate, thereby suppressing adhesion between the unvulcanized belt molded body and the heating plate, making the preparation work easier, and also making the demolding work of the conveyor belt after vulcanization easier. According to Patent Document 1, since a coated fabric or knitted fabric is used as such a sheet-like intermediate material, it is more durable than when the fabric or knitted fabric is used as is, and can be used repeatedly, and the quality of the manufactured conveyor belt can be stabilized even with repeated use.

[0003] Japanese Patent Publication No. 2012-82035

[0004] Release sheets used in the transport, storage, and packaging of adhesive products, not limited to vulcanization processes, are required to have excellent handling properties without altering the properties of such adhesive products. Therefore, this disclosure provides a release sheet that maintains sufficient adhesiveness of the adhesive product to which the release sheet is attached while also having excellent release properties.

[0005] One aspect of this disclosure provides a release sheet comprising a woven fabric base material and a resin layer on one surface of the woven fabric base material, wherein the resin layer has a release surface composed of an uneven pattern. Since such a release sheet has a resin layer on one surface of the woven fabric base material, it can maintain the tackiness of adhesive products without impairing it more effectively than a release sheet composed of a woven fabric base material alone. Furthermore, since the release surface of the release sheet is composed of an uneven pattern, adhesive products can be smoothly released. For this reason, the release sheet has excellent release properties.

[0006] According to this disclosure, it is possible to provide a release sheet that has excellent release properties while sufficiently maintaining the adhesiveness of the adhesive product to which the release sheet is attached.

[0007] Figure 1 is a cross-sectional view showing a release sheet according to one embodiment. Figures 2(A) and 2(B) are plan views showing examples of woven fabric substrates. Figure 3(A) is a diagram showing an example of the relationship between the height H of the convex portion relative to the concave portion and the peeling force when peeling the adhesive product from the release surface. Figure 3(B) is a diagram showing an example of the relationship between the area of ​​the convex portion and the peeling force when peeling the adhesive product from the release surface. Figure 4 is a plan view showing the release surface of the release sheet of Figure 1. Figure 5(A) is a diagram showing an example of a bumpy pattern, and Figure 5(B) is a diagram showing another example of a bumpy pattern. Figure 6 is a plan view showing a modified example of the release surface of the release sheet. Figure 7 is a cross-sectional view showing a release sheet according to another embodiment. Figure 8 is a diagram showing an example of a method for manufacturing a release sheet. Figure 9 is a diagram showing a release sheet wound into a roll. Figure 10 is an optical microscope image of the release surface of the release sheet in the embodiment. Figure 11 is an optical microscope image of the release surface of the release sheet in another embodiment. Figures 12(A), 12(B), and 12(C) are diagrams illustrating the evaluation criteria for assessing recovery ability and wrinkle suppression. Figure 13 is a graph showing the relationship between the height H of the uneven pattern and the peeling force. Figure 14(A) is a photograph showing an example of a roll body with winding misalignment. Figure 14(B) is a photograph showing an example of a roll body without winding misalignment.

[0008] Embodiments of this disclosure will be described below, with reference to the drawings as appropriate. However, the following embodiments are illustrative examples for illustrating this disclosure and are not intended to limit this disclosure to the following. In the description, the same reference numerals will be used for identical elements or elements having the same function, and redundant explanations will be omitted as appropriate. Furthermore, unless otherwise specified, positional relationships such as up, down, left, and right will be based on the orientation of the reference numerals shown in the drawings. In addition, the dimensional ratios of each element are not limited to those shown.

[0009] Unless otherwise specified, the materials exemplified in this disclosure may be used individually or in combination of two or more. In this disclosure, numerical ranges indicated using "~" include the respective numbers before and after "~" as the minimum and maximum values. Where multiple numerical ranges are exemplified in stages, numerical ranges obtained by replacing the upper or lower limit of the first numerical range with the upper or lower limit of a second numerical range that is narrower than the first numerical range are also included in this disclosure.

[0010] Figure 1 shows a cross-section of a release sheet 100 according to one embodiment, when cut along the stacking direction. The release sheet 100 comprises a woven fabric base material 30 and a resin layer 10 (surface resin layer) on one surface of the woven fabric base material 30. The resin layer 10 has a release surface 10A composed of an uneven pattern. The release surface 10A has convex portions 11 and concave portions 12. One surface of the woven fabric base material 30 may also have an uneven pattern. However, the uneven pattern on the release surface 10A of the resin layer 10 has a different shape from the uneven pattern on the same surface of the woven fabric base material 30.

[0011] Examples of adhesive products that can be attached to the release surface 10A of the release sheet 100 include semi-finished and finished products made of plastic and rubber (vulcanized rubber, unvulcanized rubber). Specifically, these include conveyor belts, drive belts, rubber mats, rubber products such as tires, and molten and molded plastic products.

[0012] The woven base material 30 is made of woven fabric. The release sheet 100 can have increased rigidity by being equipped with the woven base material 30. In addition, it has excellent resilience when deformed and can suppress the formation of wrinkles in the release sheet 100. The woven fabric may be a woven fabric of conductive fibers. This can suppress static electricity buildup. The conductive fibers may be, for example, natural fibers or synthetic fibers coated with metal plating. Examples of metal plating include silver plating, copper plating, nickel plating, tin plating, and gold plating. The conductive fibers may be coated with one of these platings or with two or more platings. The conductive fibers may be carbon fibers, fibers coated with carbon nanotubes (CNTs), yarn made by twisting filaments containing CNTs, or composite fibers kneaded with carbon black.

[0013] The woven base material 30 may be a plain weave fabric as shown in Figure 2(A), or a twill weave fabric as shown in Figure 2(B). The weaving method of the fabric is not limited to these, and it may be a satin weave or other weaving methods. The woven base material 30 may be made by combining warp threads 32 and weft threads 31. The woven base material 30 has voids VD. The adhesive strength between the woven base material 30 and the resin layer 10 can be adjusted by adjusting the ratio of voids VD. From the viewpoint of sufficiently increasing the adhesive strength through the anchoring effect, and from the viewpoint of making it difficult for the protrusions 11 to be crushed when the resin sheet that will become the resin layer 10 is bonded to the woven base material 30, the void ratio when the woven base material 30 is viewed in plan may be 5.0% or more, 10% or more, or 15% or more. From the viewpoint of sufficiently increasing the rigidity of the release sheet 100, and from the viewpoint of suppressing static electricity, the void ratio may be 30% or less, 20% or less, or 15% or less. The porosity may be 5.0 to 30%, or 10 to 20%. This allows for a high level of compatibility between the above-mentioned characteristics.

[0014] The porosity of the woven base material 30 can be determined by the following formula. In the following formula, the surface of the woven base material 30 is the surface facing the resin layer 10. The unit area x of the surface is, for example, 1.0 to 30 cm². ２This may be the case. Void ratio (%) = {(Unit area x of the surface of the fabric base material 30 - Area occupied by warp threads 32 and weft threads 31 in a unit area x) / Unit area x} × 100

[0015] The thickness of the woven base material 30 may be adjusted as appropriate depending on the application of the release sheet 100. The thickness of the woven base material 30 may be, for example, 10 to 1000 μm, or 100 to 500 μm.

[0016] There are no particular restrictions on the material of the warp threads 32 and weft threads 31 in the woven fabric base material 30; they may be natural fibers or synthetic fibers. Examples of natural fibers include cotton, silk, and linen. Examples of synthetic fibers include polyethylene, polypropylene, polyester, acrylic, nylon, polyurethane, vinylon, aramid, carbon fiber, and glass fiber.

[0017] The warp threads 32 and weft threads 31 may be monofilaments or multifilaments. By constructing the woven base material 30 with multifilaments, the restorative force when the release sheet 100 is deformed can be made sufficiently high. In addition, the formation of creases in the release sheet 100 can be suppressed.

[0018] The diameters of the warp threads 32 and weft threads 31 may be 100 μm to 3 mm, or 200 μm to 2 mm. The warp threads 32 and weft threads 31 may be 30 to 1000 denier, or 50 to 800 denier. This makes it difficult for the protrusions 11 to be crushed when the resin sheet that will become the resin layer 10 is bonded to the woven base material 30, and makes it possible to make the shape of the uneven pattern on the release surface 10A less affected by the surface shape of the woven base material 30.

[0019] The resin layer 10 has a release surface 10A with an uneven pattern on the side opposite to the woven fabric base material 30. The resin layer 10 may be made of synthetic resin or natural resin. From the viewpoint of processability, the resin layer 10 may be made of thermoplastic resin. Examples of thermoplastic resins include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyvinyl chloride, polystyrene, polyamide, polycarbonate, and acrylic. Of these, polyolefin resins and polyester resins are preferred, and polyolefin resins are more preferred, from the viewpoint of sufficiently improving the release properties of unvulcanized rubber.

[0020] The resin layer 10 may be composed of at least one of low-density polyethylene and linear low-density polyethylene (linear low-density polyethylene), in which case the density of the resin layer 10 is preferably 0.915 g / cm³. ３ More preferably, 0.919 g / cm³ ３ More preferably, 0.930 g / cm³ ３ That concludes the explanation. Such a resin layer 10 has particularly excellent release properties. The upper limit of the density of the resin layer 10 is 0.940 g / cm³. ３ That's fine.

[0021] The height H of the protrusion 11 relative to the recess 12 may be 5 μm or more, 10 μm or more, 50 μm or more, or 100 μm or more. By increasing the height H, a release sheet 100 with even better release properties can be made. The height H may be 800 μm or less, 600 μm or less, or 400 μm or less. By decreasing the height H, the tackiness of the adhesive product to which the release sheet 100 is attached can be sufficiently maintained. In addition, it is possible to suppress the release sheet 100 from becoming charged by static electricity. The height H may be 5 to 800 μm, 10 to 600 μm, or 15 to 400 μm. This makes it possible to achieve the above characteristics at a high level. If the height H is not constant and varies, the height H can be determined by taking the arithmetic mean of the measured values ​​taken at 10 or more arbitrarily selected positions in a scanning electron microscope (SEM) image of the cross section as shown in Figure 1. The height H may be adjusted, for example, by changing the shape of the mold used to form the raised and recessed pattern by embossing or debossing.

[0022] Figure 3(A) shows an example of the relationship between the average height H of the protrusions 11 relative to the recesses 12 on the horizontal axis and the peeling force, which is the maximum tensile stress required to peel the adhesive product from the release surface 10A, on the vertical axis. As shown in Figure 3(A), the peeling force decreases as the height H increases until the height H reaches a predetermined value a. However, once the height H exceeds a, the peeling force becomes almost constant. This tendency occurs when the difference in height of the protrusions and recesses of the adhesive product is between 0.5 × a and a. Therefore, by making the height H greater than the difference in height of the protrusions and recesses of the adhesive product, the peeling force can be sufficiently reduced.

[0023] The average thickness of the recess 12 in the resin layer 10 may be greater than or equal to the height H, or less than or equal to the height H. The thickness of the recess 12 may be 5 to 800 μm, 10 to 600 μm, or 15 to 400 μm.

[0024] The uneven pattern on the release surface 10A of the release sheet 100 has the shape shown in Figure 4. When the release surface 10A is viewed from above, the recesses 12, which consist of diamond-shaped depressions, are demarcated by linear protrusions 11. The protrusions 11 are formed so that linear first protrusions extend along a first direction and are arranged at predetermined intervals along a second direction, and linear second protrusions extend along a second direction and are arranged at predetermined intervals along the first direction, intersect with each other. As a result, adjacent recesses 12 are separated by the protrusions 11.

[0025] The line width of the protrusion 11 may be, for example, 0.1 to 20 μm, 0.5 to 10 μm, or 1 to 5 μm. This allows for further improvement of release properties while sufficiently maintaining the tackiness of the adhesive product. The line width of the protrusion 11 refers to the maximum width of the protrusion 11 when the release surface 10A is viewed from above, and can be measured, for example, using an optical microscope. As an optical microscope, for example, a microscope VHX-6000 (product name) manufactured by Keyence Corporation can be used. In this disclosure, a linear protrusion refers to a protrusion whose longitudinal length is 5 times or more the line width. If the protrusion extends in a curved shape, the longitudinal length is the maximum value of the length when two endpoints are connected by a straight line. The area of ​​one recess 12 is, for example, 1.0 to 20 mm². ２ , or 1.5 to 15 mm ２ , or 2.0 to 10 mm ２ This may be the case. This allows for further improvement of release properties while sufficiently maintaining the tackiness of the adhesive product. The area of ​​the recess 12 refers to the area of ​​one recess 12 when the release surface 10A is viewed from above, and can be measured using an optical microscope. As an optical microscope, for example, a microscope VHX-6000 (product name) manufactured by Keyence Corporation can be used.

[0026] The uneven pattern in Figure 4 is constructed by regularly repeating a predetermined unit pattern (one recess 12 and a surrounding protrusion 11) in a plan view. In Figure 4, the shapes of the protrusions 11 and recesses 12 are all uniform, but this is not limited to the case. For example, the shapes of multiple recesses 12 may differ from each other. Also, some or all of the protrusions 11 may be curved. It is not necessary for each recess 12 to be isolated; a part of the protrusion 11 may be cut out, connecting adjacent recesses 12 and presenting a co-continuous structure.

[0027] Figure 5(A) shows a three-dimensional representation of a portion of the uneven pattern on the release surface 10A. As shown in Figure 5(A), the protrusions 11 are formed in the shape of straight walls surrounding the recesses 12. When viewed in a plan view as shown in Figure 4, these straight wall-shaped protrusions 11 are connected in a linear or mesh-like pattern. These protrusions 11 make linear contact with the adhesive product. Therefore, the protrusions 11 are less likely to locally dig into the adhesive product. Consequently, when the adhesive product is pressed against the release surface 10A of the release sheet 100, local deformation of the adhesive product is suppressed, and the adhesive product can be easily released from the release surface 10A. As a result, damage to the adhesive product that occurs during release can be reduced. The uneven pattern shown in Figure 5(A) may be formed by debossing.

[0028] Figure 5(B) shows a modified example of the uneven pattern on the release surface 10A. In this modified example, the recesses 12 are formed in a groove-like shape, and the protrusions 11 are formed in an island-like shape, resulting in an overall sea-island structure. Even with such a sea-island structure for the uneven pattern on the release surface 10A, it is possible to create a release sheet 100 that has excellent release properties while sufficiently maintaining the tackiness of the adhesive product to which the release sheet 100 is attached. In the case of such an uneven pattern, the protrusions 11 make point-like contact with the adhesive product. Therefore, the protrusions 11 tend to bite into the adhesive product locally. Consequently, when the adhesive product is pressed against the release surface 10A of the release sheet 100, the adhesive product tends to deform locally more easily than with the uneven pattern in Figure 5(A), and the adhesive product tends to be more difficult to release from the release surface 10A. However, the uneven pattern in Figure 5(B) also has better release properties than when the release surface is a smooth surface. The uneven pattern shown in Figure 5(B) may be formed by embossing.

[0029] Figure 3(B) shows an example of the relationship between the area of ​​a single protrusion 11 on the horizontal axis and the peeling force required to peel the adhesive product from the release surface 10A on the vertical axis. As shown in Figure 3(B), the peeling force decreases as the area of ​​the protrusion 11 increases until the area of ​​the protrusion 11 reaches a predetermined value b. However, once the area of ​​the protrusion 11 exceeds b, the peeling force becomes almost constant. This trend occurs when the area of ​​each protrusion of the adhesive product is b. Therefore, by making the area of ​​the protrusion 11 larger than the area of ​​each protrusion of the adhesive product, the peeling force can be sufficiently reduced.

[0030] Figure 6 shows another modified example of the release surface 10A of the release sheet 100. In the example of Figure 6, the protrusions 11a have a rectangular shape in plan view. The recesses 12a are formed such that a linear first recess extends along a first direction (vertical direction) and is arranged at predetermined intervals along a second direction (horizontal direction), and a linear second recess extends along the second direction and is arranged at predetermined intervals along the first direction, intersects with each other. The first and second directions are orthogonal to each other. The area of ​​the protrusions 11a may be the same as the area of ​​the recesses 12 in Figure 4. The line width of the recesses 12a may be the same as the line width of the protrusions 11 in Figure 4. The uneven pattern shown in Figure 6 may be formed by embossing.

[0031] In FIG. 6, the recessed portions 12a are formed in a groove shape, and the protruding portions 11a are formed in an island shape, presenting a sea-island structure as a whole. However, the present invention is not limited thereto. For example, a concave-convex pattern in which the recessed portions and the protruding portions are interchanged may be employed. In this case, the release surface 10A constituted by the concave-convex pattern comes into linear contact with an adhesive product, and the release performance can be further improved. Such a concave-convex pattern may be formed by debossing.

[0032] The concave-convex pattern in FIG. 6 is also configured by regularly and repeatedly arranging unit patterns each having a predetermined geometric shape in a plan view (one protruding portion 11a and the recessed portion 12a surrounding the protruding portion 11a). In the example of FIG. 6, the shapes of the protruding portions 11a and the recessed portions 12a are uniform, but the present invention is not limited thereto. For example, the shapes of the plurality of protruding portions 11a may be different from each other. Furthermore, part or all of the recessed portions 12a may be curved. It is not essential that the protruding portions 11a are each isolated; a part of the recessed portion 12a may be cut out such that adjacent protruding portions 11a are connected to each other, and the protruding portions 11a may be in a peninsula shape.

[0033] The release sheet 100 may be obtained by unwinding a woven fabric base material 30 and a resin sheet on which a concave-convex pattern is formed and which serves as the resin layer 10, overlapping the woven fabric base material 30 and the resin sheet, and bonding them together. The resin sheet may be, for example, an LDPE film, an LLDPE film, a CPP film, an OPP film, a PET film, or a Ny film (nylon film). Examples of the bonding method include a method of sandwiching a hot-melt film between the woven fabric base material 30 and the resin sheet and performing bonding by hot melting, a method of pouring various polymers or an adhesive, and a method of applying an adhesive to the surface of the woven fabric base material 30 or the resin sheet and performing bonding.

[0034] Various methods can be cited as methods for bonding various polymers. For example, a dry lamination method may be used, in which a polymer that functions as an adhesive or a solution obtained by dissolving a polymer in a solvent is poured, and then dried by hot air drying or the like to achieve bonding. An extrusion lamination method using a molten resin or a sandwich lamination method may also be employed.

[0035] FIG. 7 shows a cross-section of a release sheet 110 according to another embodiment when cut along the lamination direction. The release sheet 110 comprises a woven fabric base material 30, a pair of resin layers 10 (surface resin layers) on both surfaces of the woven fabric base material 30, and a pair of internal resin layers 40 between the woven fabric base material 30 and the pair of resin layers 10. Each of the pair of resin layers 10 has a release surface 10A formed of a concavo-convex pattern. The woven fabric base material 30 and the resin layer 10 may be the same as those of the release sheet 100.

[0036] The internal resin layer 40 may be provided to improve the bonding reliability between the woven fabric base material 30 and the resin layer 10. The internal resin layer 40 may be formed of a synthetic resin or a natural resin. From the viewpoint of processability, the internal resin layer 40 may be formed of a thermoplastic resin. Examples of the thermoplastic resin include polyolefin resins such as polyethylene and polypropylene, polyester resins such as polyethylene terephthalate and polybutylene terephthalate, polyvinyl chloride, polystyrene, polyamide, polycarbonate, and acrylic. Among these, from the viewpoint of sufficiently increasing the bonding reliability between the woven fabric base material 30 and the resin layer 10, polyolefin resins and polyester resins are preferable, and polyolefin resins are more preferable. The polyolefin resin may be low-density polyethylene, linear low-density polyethylene, or polypropylene. The material of the internal resin layer 40 and the resin layer 10 may be the same or different from each other.

[0037] It is preferable that the resin layer 10 has a higher density than the internal resin layer 40. This makes it possible to further improve the release property of the release surface 10A while sufficiently increasing the bonding reliability between the resin layer 10 and the woven fabric base material 30. When the resin layer 10 is formed of at least one of low-density polyethylene and linear low-density polyethylene, the density range may be as described above. When the internal resin layer 40 is formed of at least one of low-density polyethylene and linear low-density polyethylene, the density of the internal resin layer 40 is 0.915 g / cm ３ and may be less than that.

[0038] The internal resin layer 40 may be an extruded resin molded by extrusion molding. The thickness of the internal resin layer 40 may be, for example, 10 to 300 μm, or 50 to 150 μm. Such an internal resin layer 40 can be smoothly molded by extrusion molding, and can sufficiently improve the bonding reliability between the woven fabric base material 30 and the resin layer 10.

[0039] In the release sheet 110, both the front surface and the back surface are release surfaces 10A. Therefore, for example, even when a laminate in which an adhesive product is laminated on the release sheet 110 is wound into a roll, the woven fabric base material 30 and the adhesive product can be kept out of contact with each other. Since such a roll can be stored and transported in a laminated state, it is excellent in handleability when continuously producing adhesive products or mass-producing adhesive products.

[0040] At least one of the resin layer 10 and the internal resin layer 40 may contain various additives. Examples of the additives include antiblocking agents, crosslinking agents, nucleating agents, fillers, reinforcing agents, slip agents, lubricants, plasticizers, antioxidants, heat stabilizers, weathering agents, light stabilizers, ultraviolet absorbers, antistatic agents, flame retardants, flame retardant auxiliaries, antifogging agents, pigments, dyes, dispersants, neutralizers, natural oils, synthetic oils, waxes, modifying resins, and the like. These may be contained singly or in combination of two or more kinds. From the viewpoint of suppressing charging caused by static electricity, it is preferable that at least one of the resin layer 10 and the internal resin layer 40 contains an antistatic agent, and it is more preferable that the resin layer 10 (surface resin layer) contains an antistatic agent.

[0041] Figure 8 shows an example of a method for manufacturing a release sheet. The woven fabric base material is unwound from a roll 62 and fed to a press roll 63. The resin sheet, which has an uneven pattern formed on one side by embossing or the like, is unwound from a roll 65 and fed to the press roll 63. Molten adhesive polymer 61 is extruded from a T-die 60 using an extruder (not shown). The adhesive polymer 61 falls onto the woven fabric base material, and the woven fabric base material and the other side of the resin sheet are bonded together by the adhesive polymer between the press roll 63 and the cooling roll 64, thereby obtaining a release sheet. At this time, the height H of the uneven pattern may fluctuate before and after bonding due to the influence of the unevenness of the woven fabric base material. For this reason, it is preferable to form the uneven pattern on the resin sheet in advance, taking into consideration the influence of the unevenness of the woven fabric base material. After the release sheet is cooled by the cooling roll 64, it is wound onto a roll body 70. In this way, a release sheet wound into a roll can be obtained.

[0042] A release sheet 110, as shown in Figure 7, can be obtained by laminating a resin sheet having an uneven pattern on one side of the woven fabric base material to the other side, such as by embossing. A roll body 70A, as shown in Figure 9, can also be obtained by winding the release sheet 110 (or release sheet 100) around a core material 72. By making the release sheets 100 and 110 into a roll body 70A, they can be easily transported and stored. The method for manufacturing the release sheet is not limited to this method. For example, a release sheet may be manufactured by laminating a woven fabric base material with a resin sheet having a flat surface, and then applying embossing or debossing to the surface of the resin sheet.

[0043] Although several embodiments and modifications have been described above, this disclosure is not limited in any way to the embodiments and modifications described above. For example, the release sheet 100 had a resin layer 10 only on one side of the woven base material 30, but the resin layer 10 may also be provided on the other side of the woven base material 30. The release sheet 110 had a pair of internal resin layers 40 and a pair of resin layers 10 on both sides of the woven base material 30, but the internal resin layer 40 and resin layer 10 may be provided only on one side of the woven base material 30. The resin layer 10 may also have an embossed or debossed pattern on the side opposite to the release surface 10A. At least a portion of the recesses in the embossed pattern on the opposite side may be filled with the internal resin layer 40.

[0044] The embodiments described above include the following: [1] A release sheet comprising a woven fabric base material and a resin layer on one surface of the woven fabric base material, wherein the resin layer has a release surface composed of an uneven pattern. [2] The release sheet according to [1], wherein at least a portion of the protrusions constituting the uneven pattern are connected in a linear manner. [3] The release sheet according to [1] or [2], comprising another resin layer on the other surface of the woven fabric base material, wherein the other resin layer has a release surface composed of the uneven pattern. [4] The release sheet according to any one of [1] to [3], wherein the woven fabric base material is composed of multifilaments. [5] The release sheet according to any one of [1] to [4], wherein, when the resin layer is a surface resin layer, an internal resin layer is provided between the woven fabric base material and the surface resin layer, and the surface resin layer has a higher density than the internal resin layer. [6] The resin layer is composed of at least one of low-density polyethylene and linear low-density polyethylene, and the density of the resin layer is 0.915 g / cm³. ３The above is true for any one of [1] to [5]. [7] The void ratio when the woven base material is viewed in plan is 5.0% or more for the release sheet according to any one of [1] to [6]. [8] The release sheet according to any one of [1] to [7] is wound in a roll. [9] The uneven pattern is composed of unit patterns having a predetermined geometric shape when viewed in plan, arranged in a regularly repeating manner for the release sheet according to any one of [1] to [8].

[10] The resin layer contains an antistatic agent for the release sheet according to any one of [1] to [9].

[11] The resin layer does not contain a release agent for the release sheet according to any one of [1] to

[10] .

[12] The thickness of the woven base material is 10 to 1000 μm for the release sheet according to any one of [1] to

[11] .

[13] The diameter of the warp and weft threads constituting the woven base material is 100 μm to 3 mm for the release sheet according to any one of [1] to

[12] .

[14] A release sheet according to any one of [2] to

[13] , wherein the line width of the protrusions when the release surface is viewed in plan is 0.1 to 20 μm.

[15] The area of ​​the recesses constituting the uneven pattern when the release surface is viewed in plan is 1.0 to 20 mm ２ A release sheet according to any one of [2] to

[14] .

[16] A release sheet according to any one of [1] to

[15] , wherein the height of the protrusions relative to the recesses in the uneven pattern is 30 to 300 μm.

[0045] The contents of this disclosure will be described in more detail with reference to examples, comparative examples, and reference examples, but this disclosure is not limited to the following examples.

[0046] [Evaluation of uneven pattern 1] (Comparative example 1) Plain weave fabric base material made of polyethylene terephthalate multifilament (300 denier) (manufactured by Nissei Co., Ltd., product name: Polyester plain weave fabric, basis weight 110 g / m) ２ A woven base material was prepared. LDPE (low-density polyethylene) was extruded onto the front and back surfaces of this woven base material to create a laminate with a flat surface. The release surface of this laminate had no uneven pattern, and both release surfaces were flat. This was used as the release sheet for Comparative Example 1.

[0047] A bonded body was obtained by pressing an adhesive compound made of natural rubber and isoprene rubber onto one release surface of a release sheet using static pressure. The pressing time during bonding was 6 hours, the load was 1.4 kN, and the temperature was 25°C. After bonding, the bonded body was cut to a width of 25 mm to serve as a measurement sample, and the tensile stress required to peel the release sheet from the adhesive compound was measured using a tensile testing machine with this measurement sample. The maximum value of the tensile stress was defined as the peel force. The tensile test was performed at a speed of 300 mm / min with a 90° peel. The results are shown in Table 1.

[0048] (Example 1) LDPE (low-density polyethylene) was extruded onto the front and back surfaces of the woven fabric substrate used in Comparative Example 1, and an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: ALEF) with an uneven pattern 1 formed on one side was bonded to each extruded resin layer to create a laminate having the cross-sectional structure shown in Figure 7. The release surface of this laminate was composed of the uneven pattern 1 (hereinafter, the same number will be assigned to uneven patterns whose recessed and convex shapes are of the same type). This was used as the release sheet for Example 1. An optical microscope image of the release surface of this release sheet is shown in Figure 10. The uneven pattern 1 constituting this release surface was composed of curved groove-shaped recesses 12b and island-shaped or peninsula-shaped convex parts 11b that were partially separated by the curved groove-shaped recesses 12b. This uneven pattern 1 is not a structure in which unit patterns having a geometric shape in a plan view are regularly repeated. The height H of the protrusion 11b relative to the recess 12b, the shape of the protrusion 11b, and the peeling force measured in the same manner as in Comparative Example 1 are shown in Table 1.

[0049] (Example 2) A release sheet was prepared in the same manner as in Example 1, except that an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: EF) with an uneven pattern 2 formed on one side was used instead of the resin sheet (product name: ALEF). This was designated as the release sheet for Example 2. An optical microscope image of the release surface of this release sheet is shown in Figure 11. The uneven pattern 2 constituting this release surface consisted of straight wall-like protrusions 11c and diamond-shaped depressions 12c. That is, the uneven pattern 2 had a three-dimensional shape as shown in Figure 5(A). The uneven pattern 2 was composed of regularly repeating unit patterns having a geometric shape in plan view. The height H of the protrusions relative to the depressions, the shape of the protrusions, and the peeling force measured in the same manner as in Comparative Example 1 are shown in Table 1.

[0050] (Example 3) A release sheet was prepared in the same manner as in Example 1, except that an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: NEF) with an uneven pattern 2 formed on one side was used instead of the resin sheet (product name: ALEF). This was designated as the release sheet for Example 3. The uneven pattern 2 on the release surface of this release sheet had the shape shown in Figure 4 when viewed from above, and consisted of a straight wall-like convex portion and a diamond-shaped recess as shown in Figure 5(A). The height H of the convex portion relative to the recess, the shape of the convex portion, and the peeling force measured in the same manner as in Comparative Example 1 are shown in Table 1.

[0051]

[0052] As shown in Table 1, it was confirmed that the peeling force can be reduced by providing an uneven pattern on the release surface.

[0053] [Evaluation of the uneven pattern 2] (Reference Example 1-1) The peeling force of an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: ALEF) with an uneven pattern 1 similar to that of the resin sheet used in Example 1 was measured. The peeling force was measured in the same manner as in Example 1. The height of the convex portion relative to the concave portion, the shape of the convex portion, and the measurement results of the peeling force are shown in Table 2.

[0054] (Reference Example 1-2) The peeling force of an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: NEF) with the same uneven pattern 2 as the resin sheet used in Example 3 was measured on its own. The peeling force was measured in the same manner as in Example 1. The height of the convex portion relative to the concave portion, the shape of the convex portion, and the measurement results of the peeling force are shown in Table 2.

[0055] (Reference Example 1-3) An LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: Mesh) with an uneven pattern 4 formed on one side (release surface) was prepared. The uneven pattern 4 had a mesh shape as shown in Figure 6 when viewed from above, and was composed of island-shaped protrusions 11a with a rectangular outline and straight groove-shaped recesses 12a. Thus, the uneven pattern 4 was composed of regularly repeating unit patterns having a geometric shape. The peeling force was measured in the same manner as in Example 1. The height of the protrusions 11a relative to the recesses 12a, the shape of the protrusions 11a, and the measurement results of the peeling force are shown in Table 2.

[0056]

[0057] [Evaluation of the uneven pattern 3] (Reference Example 2-1) The peeling force of an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: ALEF) with an uneven pattern 1 similar to that of the resin sheet used in Example 1 was measured. The peeling force was measured in the same manner as in Example 1. The height of the convex portion relative to the concave portion, the shape of the convex portion, and the measurement results of the peeling force are shown in Table 3.

[0058] (Reference Example 2-2) The peeling force was measured on an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: ALEF) with a bump pattern 1A formed on it, in which the recesses and convex parts are reversed, as in Reference Example 2-1. Specifically, bump pattern 1A had curved wall-shaped convex parts and recesses consisting of peanut shell-shaped depressions. When viewed from above, the release surface composed of bump pattern 1A has a curved arrangement of some of the convex parts. However, similar to bump pattern 1, it does not have a structure in which unit patterns with geometric shapes are regularly repeated when viewed from above. The peeling force was measured in the same manner as in Example 1. The height of the convex parts relative to the recesses, the shape of the convex parts, and the measurement results of the peeling force are shown in Table 3.

[0059] (Reference Example 2-3) The peeling force was measured on an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: EF) with a bumpy pattern 2A, in which the recesses and convex parts are reversed, as in Reference Example 1-2. Specifically, bumpy pattern 2A had island-shaped convex parts with a diamond-shaped outer shape and straight groove-shaped recesses. Thus, bumpy pattern 2A was composed of regularly repeating unit patterns having a geometric shape in plan view. The peeling force was measured in the same manner as in Example 1. The height of the convex parts relative to the recesses, the shape of the convex parts, and the measurement results of the peeling force are shown in Table 3.

[0060] (Reference Example 2-4) The peeling force of an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: EF) with the same uneven pattern 2 as the resin sheet used in Example 2 was measured on its own. The peeling force was measured in the same manner as in Example 1. The height of the convex portion relative to the concave portion, the shape of the convex portion, and the measurement results of the peeling force are shown in Table 3.

[0061] (Reference Example 2-5) The peeling force of an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: NEF) with the same uneven pattern 2A as the resin sheet used in Reference Example 2-3 was measured. The peeling force was measured in the same manner as in Example 1. The height of the convex portion relative to the concave portion, the shape of the convex portion, and the measurement results of the peeling force are shown in Table 3.

[0062] (Reference Example 2-6) The peeling force of an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: NEF) with the same uneven pattern 2 as the resin sheet used in Reference Example 2-4 was measured. The peeling force was measured in the same manner as in Example 1. The height of the convex portion relative to the concave portion, the shape of the convex portion, and the measurement results of the peeling force are shown in Table 3.

[0063]

[0064] As shown in Table 3, it was confirmed that the peeling force can be reduced when the protrusions are arranged linearly (Reference Examples 2-2, 2-4, 2-6) than when they are arranged in an island or peninsula pattern (Reference Examples 2-1, 2-3, 2-5). When the protrusions are arranged linearly, the pressure is distributed more evenly when the uneven pattern is pressed against the adhesive product than when the protrusions are arranged in an island or peninsula pattern. As a result, the protrusions are less likely to dig into the adhesive product, and the peeling force can be reduced.

[0065] [Evaluation of Resin Layer Material] (Reference Examples 3-1 to 3-9) Several types of resin sheets with flat surfaces and different materials were prepared. The materials of the resin sheets are as shown in Table 4. The peel strength of each resin sheet was measured individually. For comparison, the peel strength of the woven fabric substrate used in Comparative Example 1 was also measured individually. The peel strength was measured in the same manner as in Comparative Example 1. The measurement results are as shown in Table 4. The materials in Table 4 are as follows. Reference Example 3-9 is the woven fabric substrate used in Example 1. ・PET: Polyethylene terephthalate ・VMCPP: Polypropylene film with metal vapor-deposited on the surface ・PMMA: Polymethyl methacrylate ・Ny: Nylon ・OPP: Stretched polypropylene ・CPP: Unstretched polypropylene ・LLDPE: Linear low-density polyethylene ・LDPE: Low-density polyethylene

[0066]

[0067] As shown in Table 4, it was confirmed that the peeling force was low for LLDPE and LDPE resin sheets, and that the peeling force was lowest for LDPE resin sheets.

[0068] [Evaluation of Adhesion] (Example 4) A release sheet was prepared using the same procedure as in Example 1. The release surface of this release sheet was composed of an uneven pattern 1A having curved wall-shaped protrusions and peanut shell-shaped depressions, similar to Reference Example 2-2. The height of the protrusions relative to the depressions was 33 μm.

[0069] An adhesive compound made from natural rubber and isoprene rubber is pressed onto an aluminum plate using a SUS304 plate, and then compressed by static pressure to form a bonded body (compression area: 100 cm²). ２ The following was obtained. The pressing time during crimping was 1 minute, the load was 5 kg, and the temperature was 25°C. After crimping, the adhesive product was pulled from the crimped body using a tensile testing machine and the peel force was measured. The tensile test was performed at a speed of 300 mm / min with a 90° peel. The results are shown in Table 5 as "initial strength".

[0070] The adhesive surface of an adhesive product attached to an aluminum plate was pressed toward one of the release surfaces of the release sheet from Example 4, and a compressed body was obtained by static pressure. The pressing time during compression was 6 hours, the load was 140 kg, and the temperature was 25°C. After compression, the compressed body was cut to a size of 150 mm in width to be used as a measurement sample, and the release sheet of this measurement sample was pulled using a tensile testing machine to measure the peel force. The tensile test was performed at a speed of 300 mm / min with 90° peeling. Measurements were performed using three compressed bodies. The results for each compressed body and the average value are shown in Table 5 as "Strength after compression".

[0071] (Example 5) A release sheet was prepared using the same procedure as in Example 2. The uneven pattern 2 on the release surface of this release sheet had the shape shown in Figure 4 when viewed from above, and consisted of straight wall-like protrusions and diamond-shaped depressions as shown in Figure 5(A). The height of the protrusions relative to the depressions was 40 μm. The "initial strength" and "strength after compression" were measured in the same manner as in Example 4. The results are shown in Table 5.

[0072] (Example 6) A release sheet was prepared using the same procedure as in Example 5, except that a polyethylene terephthalate resin sheet was used instead of the resin sheet (product name: EF). The uneven pattern 2 on the release surface of this release sheet had the shape shown in Figure 4 when viewed from above, and consisted of straight wall-like protrusions and diamond-shaped depressions as shown in Figure 5(A). The height of the protrusions relative to the depressions was 36 μm. The "initial strength" and "strength after compression" were measured in the same manner as in Example 4, except that this release sheet was used. The results are shown in Table 5.

[0073] (Comparative Example 2) A release sheet was prepared using the same procedure as in Comparative Example 1. The release surface had no uneven pattern, and the two release surfaces were flat. This was used as the release sheet for Comparative Example 2. Except for using this release sheet, the "initial strength" and "strength after pressing" were measured in the same manner as in Example 4. The results are shown in Table 5.

[0074] (Comparative Example 3) A polyethylene terephthalate resin sheet with a flat surface (manufactured by Toray Industries, Inc., product name: Lumirror) was prepared. The release sheet was prepared in the same manner as in Example 1, except that this polyethylene terephthalate resin sheet was used instead of the resin sheet (product name: ALEF). The release surface had no uneven pattern, and the two release surfaces were flat. This was used as the release sheet for Comparative Example 3. The "initial strength" and "strength after pressing" were measured in the same manner as in Example 4, except that this release sheet was used. The results are shown in Table 5.

[0075] (Comparative Example 4) The "initial strength" and "strength after compression" were measured in the same manner as in Example 4, except that the woven base material used in Comparative Example 1 was used as the release sheet. The results are shown in Table 5.

[0076] (Comparative Example 5) Plain weave fabric base material made of polypropylene multifilaments (manufactured by Nissei Co., Ltd., product name: Polypropylene Plain Weave Fabric, basis weight: 110 g / m) ２ A release sheet was prepared. The "initial strength" and "strength after compression" were measured in the same manner as in Example 4, except that this was used as a release sheet. The results are shown in Table 5.

[0077]

[0078] Table 5 shows the ratio of the strength after compression (average value) to the initial strength. It was confirmed that the release sheets of Examples 4 to 6 could sufficiently maintain the tackiness of the adhesive product. In contrast, in Comparative Examples 4 and 5, where the adhesive product was directly compressed onto the woven fabric substrate, it was confirmed that the physical properties (tackiness) of the adhesive product were greatly impaired.

[0079] [Evaluation of Interlayer Adhesion Strength and Peeling Force] (Example 7) A plain weave fabric substrate was prepared as shown in Table 6. The material of the filaments (multifilaments), the number of warp threads, the number of weft threads, the thickness of the warp threads, the thickness of the weft threads, the diameter of the warp threads, and the diameter of the weft threads were as shown in Table 6. The porosity on the surface of the fabric substrate was calculated from the diameters of the warp and weft threads and the area of ​​the fabric substrate in a plan view. That is, the porosity is a value calculated by the following formula. The porosity calculated by the following formula is shown in Table 6. Porosity (%) = {(Unit area of ​​the fabric substrate surface - Area occupied by filaments in that unit area) / Unit area of ​​the fabric substrate surface} × 100

[0080] Polypropylene was extruded onto the front and back surfaces of this woven fabric substrate, and the LDPE resin sheet used in Example 2 was bonded onto this extruded resin layer so that the uneven pattern would serve as the release surface to create a release sheet α. The adhesive strength between the woven fabric substrate and the extruded resin layer (internal resin layer) of this release sheet α was measured using the same procedure as for measuring the peeling force in Example 4. The measurement results are shown in "Adhesion Strength 1" in Table 6.

[0081] Low-density polyethylene was extruded onto the front and back surfaces of another woven fabric substrate having the same material and shape, respectively. A release sheet β was then prepared by bonding the LDPE resin sheet used in Example 2 onto this extruded resin layer, with the uneven pattern acting as the release surface. The adhesive strength between the woven fabric substrate and the extruded resin layer (internal resin layer) of this release sheet β was measured using the same procedure as for measuring the peeling force in Example 4. The measurement results are shown in "Adhesion Strength 2" in Table 6.

[0082] A bonding agent made of natural rubber and isoprene rubber was pressed onto one release surface of release sheet β (a different sample from the one used to measure adhesive strength 2), and a bonded body was obtained by static pressure under the same conditions as in Comparative Example 1. After bonding, the bonded body was cut to a size of 25 mm in width to be used as a measurement sample, and the tensile stress required to peel release sheet β from the adhesive was measured in the same manner as in Comparative Example 1. The maximum value of the tensile stress was defined as the peel force. The results are shown in Table 6.

[0083] (Examples 8-14, Example 7A) Release sheets α and β were prepared in the same manner as in Example 7, except that the woven fabric base material shown in Table 6 was used, and the adhesive strength 1, 2 and peel strength were measured. The results are shown in Table 6. Note that all filaments were multifilaments. In Example 7A, a conductive fiber woven fabric (Agposs®, 100dtex, manufactured by Mitsufuji Co., Ltd., in which PET multifilaments were coated with silver plating) was used as the woven fabric base material. Note that "-" in Table 6 means that measurement was not taken.

[0084]

[0085] As shown in Table 6, it was confirmed that the higher the porosity of the woven fabric substrates in Examples 7 to 14, the higher the adhesive strength 1 and 2 tended to be. This is thought to be due to the anchoring effect caused by the voids. Regarding the release force, all woven fabric substrates tended to have better release properties with higher porosity. This is thought to be because woven fabric substrates with high porosity have more variation in the height H of the uneven pattern on the release surface, resulting in uneven adhesion to the adherend, which in turn lowers the adhesive strength and improves release properties.

[0086] [Evaluation of recovery ability and wrinkle suppression] Each release sheet from Examples 7 to 14 was cut out to obtain a sample S with sides of 10 cm. This sample S was folded in half, and the degree to which it recovered was evaluated according to the following criteria. As a result, the evaluation results for all release sheets from Examples 7 to 14 were "A".

[0087] Evaluation A: After 5 minutes, the angle θ of sample S is 90° or greater (state shown in Figure 12(A)), and after 1 hour it returns to the state before folding (θ = 180°) (state shown in Figure 12(B)). Evaluation B: After 5 minutes, the angle θ of sample S is 90° or greater (state shown in Figure 12(A)), and after 1 hour the angle θ of sample S is less than 180°, and wrinkles remain. Evaluation C: After 5 minutes, the angle θ of sample S is less than 90° (state shown in Figure 12(C)).

[0088] (Comparative Example 6) The recovery ability and wrinkle suppression of the woven fabric substrate used in Comparative Example 1 were evaluated in the same manner as the release sheets in Examples 7 to 14. The results are shown in Table 7.

[0089] (Comparative Examples 7 and 8) A polyethylene terephthalate resin sheet with a flat surface (thickness: 300 μm) and a polyethylene resin sheet with a flat surface (thickness: 300 μm) were prepared. The recovery ability and wrinkle suppression of these resin sheets were evaluated in the same manner as for the release sheets in Examples 7 to 14. The results are shown in Table 7.

[0090] (Example 15) Plain weave fabric base material made of polyethylene terephthalate monofilament (400 denier) (manufactured by Nissei Co., Ltd., product name: Monofilament Plain Weave Fabric, basis weight: 80 g / m) ２ A woven fabric substrate was prepared. LDPE (low-density polyethylene) was extruded onto the front and back surfaces of this woven fabric substrate, and a polyethylene terephthalate resin sheet (manufactured by Godo Resin Kogyo Co., Ltd., product name: PG-47) with an uneven pattern 1 formed on one side was bonded to this extruded resin layer to create a laminate. This laminate had the laminated structure shown in Figure 7. This was used as the release sheet for Example 15. The recovery ability and wrinkle suppression of the release sheet for Example 15 were evaluated in the same manner as the release sheets for Examples 7 to 14. The results are shown in Table 7.

[0091] (Example 16) A release sheet was prepared in the same manner as in Example 15, except that an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: NEF) was used instead of a polyethylene terephthalate resin sheet, and its recovery ability and wrinkle suppression were evaluated. The results are shown in Table 7.

[0092] (Example 17) Plain weave fabric base material made of polyethylene terephthalate multifilament (300 denier) (manufactured by Nissei Co., Ltd., product name: Polyester Plain Weave Fabric, basis weight: 110 g / m) ２ A woven fabric base material was prepared. A release sheet was made in the same manner as in Example 15, except that this woven fabric base material was used, and its recovery ability and wrinkle suppression were evaluated. The results are shown in Table 7.

[0093] (Example 18) Instead of a polyethylene terephthalate resin sheet, an LDPE resin sheet was used (manufactured by Nippon Polyethylene Co., Ltd., product name: LC605Y, density: 0.918 g / cm³). ３ A release sheet was prepared in the same manner as in Example 17, except that the material used was [material name missing], and its recovery ability and wrinkle suppression were evaluated. The results are shown in Table 7.

[0094]

[0095] The angle θ in Table 7 is the value after standing for 5 minutes. As shown in Table 7, it was confirmed that the release sheet, which has both a woven base material composed of multifilaments and a resin sheet, has superior recovery ability and can suppress the occurrence of wrinkles compared to the resin sheet alone.

[0096] [Influence of resin layer density] The following LLDPE resin sheets with flat surfaces were prepared: • Reference Example 4-1: Manufactured by Ube Maruzen Polyethylene Co., Ltd., Product Name: 145EC • Reference Example 4-2: Manufactured by Ube Maruzen Polyethylene Co., Ltd., Product Name: Yumerit® 021GT • Reference Example 4-3: Manufactured by Ube Maruzen Polyethylene Co., Ltd., Product Name: Yumerit® 022GS

[0097] The peel strength of each resin sheet was measured individually. The peel strength was measured in the same manner as in Comparative Example 1. The measurement results are shown in Table 8. The density (catalog value) is also shown in Table 8.

[0098]

[0099] As shown in Table 8, it was confirmed that the higher the density of the resin layer, the lower the peeling force and the improved mold release properties.

[0100] [Evaluation of Variation in Peeling Force] (Examples 19-28) Except for using an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: ALEF) with the uneven pattern 1A of Reference Example 2-2 formed on it, release sheets for Examples 19-28 were prepared using the same procedure as in Example 1, with the release surface composed of the uneven pattern 1A. The release sheets for each example were prepared using resin sheets with different heights H of the uneven pattern 1A by changing the embossing conditions. The release surface of each example was composed of an uneven pattern 1A having curved wall-shaped protrusions and recesses consisting of peanut shell-shaped depressions. In other words, this uneven pattern 1A did not have a structure in which unit patterns having geometric shapes in a plan view were regularly repeated. The heights H of the protrusions relative to the recesses for each example are shown in Table 9. In Examples 19-28, three positions were selected on the release surface of each resin sheet (n=3), and the peeling force was measured at each position in the same manner as in Comparative Example 1. The mean and standard deviation of the peeling force are shown in Table 9. Figure 13 plots the mean peeling force.

[0101]

[0102] In Examples 19-28 shown in Table 9, the variation due to the position of the release surface was small for all heights H. In Examples 22-26, the average release force was 0.7 [N / 25mm] or less, confirming excellent release properties. The RMS (root mean square of the standard deviation σ) was calculated from the standard deviation σ of Examples 19-28 and was found to be 0.048 [N / 25mm].

[0103] (Examples 29-40) Release sheets for Examples 29-40 were manufactured in the same manner as in Example 1, except that an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: NEF) with a raised and recessed pattern 2 formed on one side was used instead of the resin sheet (product name: ALEF). The release sheets for each example were manufactured using resin sheets with different heights H of the raised and recessed patterns 2 by changing the embossing conditions. As shown in Table 10, the release surfaces of each example had raised and recessed patterns 2 with different heights H. The raised and recessed patterns 2 on the release surfaces of the release sheets of each example all had the shape shown in Figure 4 when viewed from above, and were composed of straight wall-like protrusions and diamond-shaped depressions as shown in Figure 5(A). That is, this raised and recessed pattern 2 had a structure in which unit patterns having geometric shapes when viewed from above were regularly repeated. In Examples 29 to 40, three locations were selected on the release surface of each resin sheet (n=3), and the peel force was measured at each location in the same manner as in Comparative Example 1. The average value and standard deviation of the peel force are shown in Table 10. The average value of the peel force is plotted in Figure 13.

[0104]

[0105] In Examples 29-40 shown in Table 10, the variation due to the position of the release surface was sufficiently small for all heights H. Comparing the standard deviations in Table 9 and Table 10, the standard deviation in Table 10 was even smaller. In Examples 32-40, the average value of the release force was 0.7 [N / 25mm] or less, confirming excellent release properties. The RMS (root mean square of the standard deviation σ) was calculated from the standard deviation σ of Examples 29-40 and was found to be 0.024 [N / 25mm].

[0106] These results confirm that pattern 2 tends to reduce the variation in peeling force compared to pattern 1A. Furthermore, as shown in Figure 13, it was confirmed that with pattern 2, the peeling force does not increase significantly even when the height H is large, and that it tends to be less affected by height H than pattern 1A. Possible reasons for these tendencies include the fact that pattern 2 has geometrically shaped unit patterns arranged in a regular repeating manner, resulting in a uniform distribution of pressure during pressing, and that the convex parts are connected in a linear fashion, reducing the penetration into the adhesive product during pressing even when the height H is large.

[0107] [Evaluation of electrostatic discharge] (Example 41) A plain weave fabric base material used in Example 10 was prepared. LDPE (manufactured by Nippon Polyethylene Co., Ltd., product name: LC605Y, density: 0.918 g / cm³) was applied to the front and back surfaces of this fabric base material. ３ A release sheet was prepared by extruding a resin layer and bonding an antistatic resin sheet, which had an uneven pattern 2 formed on one side, onto this extruded resin layer. The antistatic resin sheet was molded by mixing 3 parts by mass of an antistatic agent (manufactured by Dainichi Seika Kogyo Co., Ltd., product name: Neocon PE-M D-728 (SP) Black) with 100 parts by mass of LDPE (product name: NEF) manufactured by Ishijima Chemical Industry Co., Ltd. The release sheet thus prepared had a release surface on which the uneven pattern 2 was formed. The height H of the uneven pattern 2 was as shown in Table 11.

[0108] The release force on the release surface was measured in the same manner as in Comparative Example 1. Furthermore, the electrostatic decay on the release surface was measured in accordance with Method B (Half-life measurement method) of JIS L1094:2014 (Test method for electrostatic properties of woven and knitted fabrics). A HONESTMETER H-0110 (product name) manufactured by Shishido Electrostatic Co., Ltd. was used to measure the electrostatic decay. The release surface was charged by corona discharge, and the electrostatic decay (residual charge rate) was measured under the following measurement conditions. These measurement results are shown in Table 11. Note that the electrostatic decay (%) in this specification is calculated as V1 × 100 / V0, where V0 is the initial charged voltage after charging the release surface by corona discharge for 60 seconds, and V1 is the residual charged voltage after 90 seconds. • Applied voltage: -3.0kV • Application time: 60 seconds • Decay time: 90 seconds

[0109] (Example 42) A plain weave fabric base material was prepared, as used in Example 10. LDPE (manufactured by Nippon Polyethylene Co., Ltd., product name: LC605Y, density: 0.918 g / cm³) was applied to the front and back surfaces of this fabric base material. ３ A resin composition was obtained by mixing 25 to 35 parts by mass of an antistatic agent (manufactured by Dainichi Seika Kogyo Co., Ltd., product name: Neocon PE-M D-728 (SP) Black) with 100 parts by mass of resin, and the mixture was extruded. A release sheet was then prepared by bonding an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: NEF) with an uneven pattern 2 formed on one side to this extruded resin layer. The release sheet thus prepared had a release surface with the uneven pattern 2 formed thereon. The height H of the uneven pattern 2 was as shown in Table 11. The peeling force and electrostatic decay on the release surface were measured in the same manner as in Example 41. The measurement results are shown in Table 11.

[0110] (Example 43) A woven fabric of conductive fibers used in Example 7A was prepared as the woven fabric base material. LDPE (manufactured by Nippon Polyethylene Co., Ltd., product name: LC605Y, density: 0.918 g / cm³) was applied to the front and back surfaces of this woven fabric base material. ３A release sheet was fabricated by extruding a resin layer and bonding an LDPE resin sheet (manufactured by Ishijima Chemical Industry Co., Ltd., product name: NEF) with an uneven pattern 2 formed on one side onto this extruded resin layer. The release sheet fabricated in this way had a release surface with the uneven pattern 2 formed thereon. The height H of the uneven pattern 2 was as shown in Table 11. The peeling force and electrostatic decay on the release surface were measured in the same manner as in Example 41. These measurement results are shown in Table 11.

[0111]

[0112] Table 11 shows which components of the release sheet are responsible for the static charge suppression (the part that suppresses static charge). As shown in Table 11, it was confirmed that Example 41, in which the surface resin layer having the release surface contains an antistatic agent, exhibited smaller static charge attenuation than Example 42, in which the internal resin layer contains an antistatic agent, and Example 43, in which the woven base material is composed of conductive fibers. Therefore, from the viewpoint of static charge suppression, it was found that it is preferable for the surface resin layer to contain an antistatic agent.

[0113] (Example 44) A conductive fiber fabric used in Example 7A was prepared as the fabric base material. A release sheet was prepared in the same manner as in Example 41, except that this conductive fabric was used and the height H of the uneven pattern 2 in the antistatic resin sheet with an uneven pattern 2 formed on one side was changed as shown in Table 12. The peeling force and static charge decay on the release surface were measured in the same manner as in Example 41. These measurement results are shown in Table 12.

[0114] (Examples 45-47) Release sheets were prepared in the same manner as in Example 41, except that the height H of the uneven pattern 2 on the release surface changed as shown in Table 12 due to the use of the woven base material shown in Table 12 and the use of different woven base materials. The filaments in the woven base materials of Examples 45-47 are all multifilaments. The peeling force and electrostatic decay on the release surface of each release sheet were measured in the same manner as in Example 41. These measurement results are shown in Table 12.

[0115]

[0116] Examples 44-47 in Table 12 all exhibited low static charge decay because the surface resin layer with a release surface contained an antistatic agent. Comparing Example 41 in Table 11 with Examples 45-47 in Table 12, it was confirmed that a smaller height H of the uneven pattern 2 resulted in lower static charge decay and a tendency to suppress static charge.

[0117] (Examples 48-51) As shown in Table 13, LDPE resin sheets (manufactured by Ishijima Chemical Industry Co., Ltd., product name: NEF) were embossed to produce LDPE resin sheets with different heights H of the uneven patterns 2. Release sheets were produced in the same manner as in Example 42, except that these resin sheets were used. Then, the peeling force and electrostatic decay on the release surface were measured in the same manner as in Example 41. The results of these measurements are shown in Table 13.

[0118]

[0119] Examples 48-51 in Table 13, like Example 42 in Table 11, have an internal resin layer containing an antistatic agent. Comparing Example 42 in Table 11 with Examples 48-51 in Table 13, it was confirmed that a lower height H of the uneven pattern 2 tends to result in less static charge attenuation and improved antistatic properties.

[0120] (Examples 52, 53) As shown in Table 14, release sheets were prepared in the same manner as in Example 50, except that LDPE resin sheets (manufactured by Ishijima Chemical Industry Co., Ltd., product name: NEF) with different uneven patterns and their height H were used. For comparison, Example 50 is also shown in Table 14. The release surface of Example 52 had an uneven pattern 1A similar to that of Reference Example 2-2. The release surface of Example 53 had an uneven pattern 4 similar to that of Reference Example 1-3. The peeling force and electrostatic decay on the release surface were measured in the same manner as in Example 50. These measurement results are shown in Table 14.

[0121]

[0122] Examples 52 and 53 in Table 14, like Examples 48 to 51 in Table 13, have an internal resin layer containing an antistatic agent. Examples 52, 53 and Examples 50 and 51 (Table 13) showed reduced static charge decay and were confirmed to have good antistatic properties.

[0123] (Examples 54-57) Release sheets were prepared in the same manner as in Example 42, except that the woven base material was changed to the woven fabric shown in Table 15. Table 15 also shows the woven fabric used in Example 42 and the measurement results. The material of the filaments (multifilaments), the number of warp and weft threads, and the void ratio calculated in the same manner as in Table 6 for Examples 42, 54-57 are as shown in Table 15. In Example 56, the woven base material was the conductive fiber woven fabric used in Example 7A. Each release sheet prepared in this manner for Examples 42, 54-57 had a release surface with an uneven pattern 2 formed thereon. The height H of the uneven pattern 2 is as shown in Table 15. The peeling force and charge decay on the release surface were measured in the same manner as in Example 42. These measurement results are shown in Table 15.

[0124]

[0125] As shown in Table 15, it was confirmed that the greater the porosity of the woven fabric base material, the smaller the electrostatic discharge tends to be.

[0126] [Evaluation of Slipperiness 1] From the viewpoint of stability (prevention of winding misalignment) in the manufacturing process of the release sheet, the influence of the material of the resin sheet and the presence or absence of an uneven pattern on the slipperiness was evaluated. The evaluation results are shown in Table 16. Reference Example 5-1 in Table 16 is an LDPE resin sheet used when manufacturing the release sheet of Example 2, and had an uneven pattern as shown in Figures 4 and 5(A). The height H of the convex portion relative to the concave portion was 40 μm.

[0127] Reference Example 5-2 is a commercially available release film (manufactured by TOPPAN Corporation) having a silicone-based release agent coating layer on the surface of a PET resin sheet, and is a smooth resin sheet without an uneven pattern. Reference Example 5-3 is a commercially available release film (manufactured by Unitika Ltd., Unipeel®) having an olefin-based release agent coating layer on the surface of a PET resin sheet, and is a smooth film without an uneven pattern. Reference Example 5-4 is a single-layer PET film without surface treatment (manufactured by Futamura Chemical Co., Ltd., product name: FE2001), and is a smooth film without an uneven pattern. Reference Example 5-5 is an LDPE resin sheet with a smooth surface (manufactured by Tamapoly Co., Ltd., product name: V-1). Reference Example 5-6 is an unoriented polypropylene resin sheet with a smooth surface.

[0128] Two sheets of each type of resin were prepared, and the slipperiness was measured by overlapping the resin sheets. The measurement was performed in accordance with JIS K7125:1999 "Plastics - Films and Sheets - Test Method for Coefficient of Friction". Using a friction measuring instrument (Friction Tester TR-2, manufactured by Toyo Seiki Seisakusho), a resin sheet (first resin sheet) was placed on the underside of a 200g thread, and another resin sheet (second resin sheet) was placed on a stainless steel plate with a horizontal surface, so that the second resin sheet was in contact with the first resin sheet on a surface with an area of ​​6.3 cm x 6.3 cm. The thread was then slid 60 mm (= distance traveled) on the stainless steel plate at a speed of 100 mm / min, and the static friction coefficient was calculated based on the maximum static friction force measured at this time. The measurement was performed three times for each sample, and the average value was calculated. In addition, in this evaluation, the static friction coefficient between resin sheets (surface / surface) was measured to simulate the slippage between resin sheets when wound into a roll. The results are shown in Table 16.

[0129]

[0130] As shown in Table 16, Reference Example 5-2 (static friction coefficient: 0.01) coated with a silicone-based release agent and Reference Example 5-3 (static friction coefficient: 0.04) coated with an olefin-based release agent both exhibited extremely low static friction coefficients and were found to be very slippery. While these release coatings contribute to improved release properties, they make the resin sheets significantly more slippery, which is likely to cause misalignment when winding them into a roll and when handling the roll. An example of a roll with misalignment is shown in Figure 14(A). Figure 14(B) shows a roll without misalignment when using a film with moderately suppressed slipperiness.

[0131] The static friction coefficient of the untreated PET resin sheet (Reference Example 5-4) was 0.41, while the static friction coefficient of the LDPE resin sheet (Reference Example 5-5) was 0.29, confirming that the LDPE resin sheet is more slippery than the PET resin sheet. Although LDPE is a material with superior release properties compared to PET, on the other hand, it has a lower friction coefficient between resin sheets, which tends to cause misalignment during winding.

[0132] On the other hand, the static friction coefficient of Reference Example 5-1, in which an uneven pattern 2 (height H: 40 μm) was formed on the surface of an LDPE resin sheet, was 0.40. This was a significant increase compared to a smooth LDPE resin sheet (Reference Example 5-5: 0.29) and was equivalent to that of a smooth PET resin sheet (Reference Example 5-4: 0.41). This is thought to be because the unevenness of the resin sheets interlocked, creating sliding resistance. In other words, it was shown that even when using slippery materials such as LDPE, forming a specific uneven pattern on the surface can effectively suppress winding misalignment when winding into a roll and when handling the roll.

[0133] [Evaluation of Slipperiness 2] Next, the effect of the height H of the uneven pattern on the slipperiness was evaluated. The evaluation results are shown in Table 17. Reference Example 6-1 is a smooth LDPE resin sheet without an uneven pattern (height H: 0 μm, manufactured by Ishijima Chemical Industry Co., Ltd., product name: NEF). Reference Examples 6-2 to 6-9 are all resin sheets in which an uneven pattern 2 similar to that of Example 2 is formed on the surface of the resin sheet of Reference Example 6-1. This uneven pattern 2 consists of recesses made up of diamond-shaped depressions and convex parts in the shape of straight walls, and has the shape shown in Figures 4 and 5(A). As shown in Table 17, the height H of the convex parts relative to the recesses differs for each of the Reference Examples 6-2 to 6-9.

[0134] The slipperiness was measured using the same method as in [Slipperiness Evaluation 1]. Specifically, in accordance with JIS K7125:1999, the static friction coefficient between resin sheets was measured using a friction measuring instrument (Friction Tester TR-2, manufactured by Toyo Seiki Seisakusho). Measurements were performed up to six times for each sample, and the average value (AVE) was calculated. Note that "-" in Table 17 indicates that measurement was not performed. The results of the static friction coefficient measurement are shown in Table 17.

[0135]

[0136] As shown in Table 17, the static friction coefficient of a smooth LDPE resin sheet without a textured pattern (Reference Example 6-1) was 0.16, which is lower than that of a smooth PET resin sheet (Reference Example 5-4 in Table 16, static friction coefficient: 0.41), similar to Reference Example 5-5 in Table 16 (smooth LDPE resin sheet, static friction coefficient: 0.29). In other words, it was confirmed once again that a smooth LDPE resin sheet without a textured pattern is more slippery than a PET resin sheet.

[0137] As the height H of the uneven pattern increased, the static friction coefficient generally tended to increase. When the height H was 40 μm (Reference Example 6-7), the static friction coefficient rose to 0.43, which was equivalent to or better than that of a smooth PET resin sheet. When the height H was 230 μm (Reference Example 6-8) and 310 μm (Reference Example 6-9), the static friction coefficients were 0.39 and 0.44, respectively, which were at a level equivalent to that of a smooth PET resin sheet (Reference Example 5-4 in Table 16).

[0138] These results demonstrate that even when using slippery materials such as LDPE, increasing the height H of the uneven pattern to a certain extent can provide slip resistance equivalent to or greater than that of a smooth PET resin sheet. This is thought to be because the unevenness of the resin sheets interlocks as the height H increases, increasing the slip resistance. In other words, by setting the height H of the uneven pattern within an appropriate range, it is possible to effectively suppress winding misalignment when winding the material into a roll and when handling the roll, even when using slippery materials such as LDPE.

[0139] [Evaluation of achieving both release properties and suppression of winding misalignment] The resin sheets of Reference Examples 6-1 to 6-9 shown in Table 17 were wound into rolls, and the alignment of the end faces was visually checked. Those that did not exhibit winding misalignment, as shown in Figure 14(B), were evaluated as "A," and those that exhibited winding misalignment (bamboo shoot-shaped deformation), as shown in Figure 14(A), were evaluated as "B." The evaluation results are shown in Table 18. Table 18 also shows the average values ​​of the height H of the unevenness pattern and the static friction coefficient for the resin sheets of Reference Examples 6-1 to 6-9.

[0140] Table 18 also shows the measurement results of the peel force of the release sheets for each example shown in Table 10. Note that Comparative Example 9 in Table 18 is a release sheet prepared in the same manner as in Example 1, except that it used the resin sheet from Reference Example 6-1. The peel force on the release surface of this release sheet was also measured in the same manner as in Comparative Example 1. The release properties of each release sheet were evaluated based on the following evaluation criteria. The evaluation results are shown in Table 18. A: Peel force less than 0.60 N / 25 mm B: Peel force 0.60 N / 25 mm or more and less than 1.0 N / 25 mm C: Peel force 1.0 N / 25 mm or more

[0141]

[0142] As shown in Table 18, when the height H of the uneven pattern was less than 30 μm, the static friction coefficient was low (less than 0.3), and winding misalignment occurred. On the other hand, when the height H was 40 μm or more, the static friction coefficient was high (0.39 or more), and winding misalignment could be prevented.

[0143] Regarding release properties, extremely good results (evaluation A) were obtained when the height H of the uneven pattern was approximately 20 μm or more. When the height H exceeded 300 μm, the release force became 0.60 N, and the release properties tended to decrease slightly. However, it still exhibited significantly better release properties than the release sheet with a flat resin sheet (Comparative Example 9).

[0144] From these results, it was confirmed that by setting the height H of the uneven pattern in the range of 30 to 300 μm, it is possible to achieve a high level of both excellent mold release properties and prevention of winding misalignment.

[0145] 10... Resin layer, 10A... Release surface, 11, 11a, 11b, 11c... Convex part, 12, 12a, 12b, 12c... Recess, 30... Woven base material, 31... Weft thread, 32... Warp thread, 40... Internal resin layer, 60... T-die, 61... Adhesive polymer, 62, 65... Roll, 63... Press roll, 64... Cooling roll, 70, 70A... Roll body, 72... Core material, 100, 110... Release sheet.

Claims

1. A release sheet comprising a woven fabric base material and a resin layer on one surface of the woven fabric base material, wherein the resin layer has a release surface composed of an uneven pattern.

2. The release sheet according to claim 1, wherein at least a portion of the protrusions constituting the uneven pattern are connected in a linear manner.

3. The release sheet according to claim 1 or 2, wherein another resin layer is provided on the other surface of the woven fabric base material, and the other resin layer has a release surface composed of the uneven pattern.

4. The release sheet according to claim 1 or 2, wherein the woven base material is composed of multifilaments.

5. The release sheet according to claim 1 or 2, wherein, when the resin layer is the surface resin layer, an internal resin layer is provided between the woven fabric substrate and the surface resin layer, and the surface resin layer has a higher density than the internal resin layer.

6. The resin layer is composed of at least one of low-density polyethylene and linear low-density polyethylene, and the density of the resin layer is 0.915 g / cm³. ３ The release sheet according to claim 1 or 2.

7. The release sheet according to claim 1 or 2, wherein the porosity of the woven base material when viewed in plan is 5.0% or more.

8. The release sheet according to claim 1 or 2, which is wound in a roll.

9. The release sheet according to claim 1 or 2, wherein the uneven pattern is composed of regularly repeated unit patterns having a predetermined geometric shape in a plan view.

10. The release sheet according to claim 1 or 2, wherein the resin layer contains an antistatic agent.

11. The release sheet according to claim 1 or 2, wherein the resin layer does not contain a release agent.

12. The release sheet according to claim 1 or 2, wherein the thickness of the woven base material is 10 to 1000 μm.

13. The release sheet according to claim 1 or 2, wherein the diameters of the warp and weft threads constituting the woven base material are 100 μm to 3 mm.

14. The release sheet according to claim 2, wherein the line width of the protrusions when the release surface is viewed from above is 0.1 to 20 μm.

15. The area of ​​the recesses constituting the uneven pattern when the release surface is viewed from above is 1.0 to 20 mm². ２ The release sheet according to claim 2 or 14.

16. The release sheet according to claim 1 or 2, wherein the height of the protrusions relative to the recesses in the uneven pattern is 30 to 300 μm.

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