Porous resin sheet and carrier tape

Abstract

The present invention addresses the problem of providing: a porous resin sheet which can be shaped without being subjected to a special step such as heating or pressure reduction while suppressing the amount of paper powder; and a carrier tape using the same. The present invention relates to a porous resin sheet provided with a porous resin layer comprising a thermoplastic resin, the porous resin layer having a thickness of 40-350 [mu] m and a porosity of 35-80%, the porous resin layer comprising a base material layer and a first surface layer, the base material layer and the first surface layer each comprising a thermoplastic resin and particles, the content of the particles in the base material layer is 20-45% by mass, and the content of the particles in the first surface layer is 45-80% by mass.

Description

Technical Field

[0001] The present invention relates to a porous resin sheet and a carrier tape. Background Art

[0002] In order to facilitate the handling of electronic components that are becoming increasingly smaller, carrier tapes are used. The carrier tapes contain electronic components one by one in their pockets, so that the electronic components can be easily protected from loss or damage.

[0003] Carrier tapes are usually made of pulp paper, polyvinyl chloride, polystyrene, amorphous polyethylene terephthalate, polycarbonate, polypropylene and other resins. Although carrier tapes made of pulp paper (e.g., Patent Document 1) are cheap, it is difficult to form small-sized pockets. In addition, there is a problem that burrs (paper dust) are easily generated on the processed cross section when punching the transport holes. On the other hand, although carrier tapes made of resins are not prone to paper dust and can form large-sized pockets, they are relatively lacking in lightness. In addition, heating and decompression (vacuum) processes are required when shaping the pockets, which is disadvantageous in terms of manufacturing costs. Prior art literature Patent Literature

[0004] Patent Document 1: Japanese Patent Application Publication No. 2000-43975 Summary of the invention Technical problem to be solved by the invention

[0005] An object of the present invention is to provide a porous resin sheet capable of being shaped without undergoing a special process such as heating or decompression while suppressing the amount of paper powder, and a carrier tape using the same. Technical methods for solving technical problems

[0006] The present inventors conducted intensive research to solve the above-mentioned technical problems, and found that by utilizing a porous resin sheet having a porous resin layer containing a thermoplastic resin, the thickness and porosity of the porous resin layer being within a specific range, the porous resin layer comprising a substrate layer and a first surface layer, the substrate layer and the first surface layer both containing thermoplastic resin and particles, and the content of particles in the substrate layer and the first surface layer being within a specific range, a porous resin sheet and a carrier using the same can be obtained, and the porous resin sheet can be shaped without undergoing special processes such as heating and decompression while suppressing the amount of paper powder, thereby completing the present invention.

[0007] That is, the present invention is as follows. <1> A porous resin sheet comprising a porous resin layer containing a thermoplastic resin, The thickness of the porous resin layer is 40 to 350 μm. The porosity of the porous resin layer is 35-80%. The porous resin layer comprises a substrate layer and a first surface layer, The substrate layer and the first surface layer both contain thermoplastic resin and particles, The content of the particles in the substrate layer is 20 to 45% by mass. The content of the particles in the first surface layer is 45 to 80% by mass. <2> The porous resin sheet according to <1>, wherein the first surface layer is a porous uniaxially stretched resin layer, and the base layer is a porous biaxially stretched resin layer. <3> The porous resin sheet according to <1> or <2>, wherein the first surface layer has a thickness of 5 μm or more. <4> The porous resin sheet according to any one of <1> to <3>, wherein the first surface layer has a thickness of 10 μm or more. <5> The porous resin sheet according to any one of <1> to <4>, wherein the porous resin layer further includes a second surface layer on a surface of the base material layer opposite to the first surface layer. <6> The porous resin sheet according to any one of <1> to <5>, wherein a ratio of the porosity of the first surface layer to the porosity of the base layer is 0.80 to 1.20.

[0008] <7> The porous resin sheet according to any one of <1> to <6>, wherein the breaking strength in the width direction of the porous resin sheet is 0.1 to 10 kgf / mm 2 . <8> The porous resin sheet according to any one of <1> to <7>, wherein the porous resin sheet is used for a carrier tape. <9> A carrier tape comprising the porous resin sheet according to any one of <1> to <8>, and a pocket formed in the porous resin sheet. Effects of the Invention

[0009] According to the present invention, it is possible to provide a porous resin sheet capable of being shaped without undergoing a special process such as heating or decompression while suppressing the amount of paper powder, and a carrier tape using the same. BRIEF DESCRIPTION OF THE DRAWINGS

[0010] Figure 1 This is a diagram showing one embodiment of a cross section in the lamination direction of the porous resin sheet of the present invention. Figure 2 This is a diagram showing a cross section in the lamination direction in another embodiment of the porous resin sheet of the present invention. Figure 3 It is a diagram showing a cross section in the lamination direction of a porous resin sheet of a comparative example. Figure 4 This is a diagram showing a carrier tape obtained by using a porous resin sheet in another embodiment of the present invention, and is a diagram showing a cross section in the lamination direction passing through a pocket. DETAILED DESCRIPTION

[0011] The porous resin sheet of the present invention will be described in detail below. The following is an example (representative example) of the present invention, and the present invention is not limited thereto. In addition, in this specification, the numerical range "A to B" means "A or more and B or less".

[0012] The present invention relates to a porous resin sheet, which has a porous resin layer containing a thermoplastic resin, the thickness of the porous resin layer is 40 to 350 μm, the porosity of the porous resin layer is 35 to 80%, the porous resin layer comprises a substrate layer and a first surface layer, the substrate layer and the first surface layer both contain thermoplastic resin and particles, the content of the particles in the substrate layer is 20 to 45% by mass, and the content of the particles in the first surface layer is 45 to 80% by mass. In a porous resin sheet having a porous resin layer containing a thermoplastic resin, by making the thickness and porosity of the porous resin layer within a specific range, and the porous resin layer includes a substrate layer and a first surface layer, and both the substrate layer and the first surface layer contain thermoplastic resin and particles, and making the content of particles in the substrate layer and the first surface layer within a specific range, it is possible to obtain a carrier tape that is shaped without undergoing special processes such as heating and decompression while suppressing the amount of paper powder.

[0013] <Porous resin layer> The porous resin sheet of the present invention has a porous resin layer containing a thermoplastic resin, the thickness of the porous resin layer is 40 to 350 μm, the porosity of the porous resin layer is 35 to 80%, the porous resin layer includes a substrate layer and a first surface layer, the substrate layer and the first surface layer both contain thermoplastic resin and particles, the content of the particles in the substrate layer is 20 to 45% by mass, and the content of the particles in the first surface layer is 45 to 80% by mass. By having such a porous resin layer, it is easy to make the carrier lightweight. In addition, by increasing the porosity, an escape place for components such as compressed resin and particles is formed during shaping, which can improve the shaping property.

[0014] [Thermoplastic resin contained in porous resin layer] By making the porous resin layer contain a thermoplastic resin, the generation of paper dust can be suppressed compared with pulp paper, and the water resistance is increased, and the dimensional change caused by humidity can be suppressed. The thermoplastic resin contained in the porous resin layer is not particularly limited, and for example, polyolefin resins such as polyethylene resin and polypropylene resin, polyvinyl chloride resin, polyethylene terephthalate resin, polycarbonate resin, polymethylpentene-1, cyclic olefins, etc. can be cited. As another example of the thermoplastic resin contained in the porous resin layer, a mixture containing two or more of the thermoplastic resins can be cited. Among them, from the viewpoint described below, polyolefin resins such as polyethylene resin and polypropylene resin are preferred, and polyethylene resin and polypropylene resin are more preferred. The thermoplastic resin preferably contains only polyolefin resins, and more preferably contains only polyethylene resin and polypropylene resin.

[0015] The content of the thermoplastic resin in the porous resin layer is preferably 35% by mass or more, more preferably 40% by mass or more, and further preferably 45% by mass or more. In addition, the above content is preferably 80% by mass or less, more preferably 70% by mass or less, and further preferably 60% by mass or less. By making the content of the thermoplastic resin 35% by mass or more, it is easy to reduce the generation of paper dust and improve water resistance.

[0016] (Polypropylene resin) By using a polypropylene resin in the porous resin layer, flexibility is imparted to the porous resin layer, and the porous resin layer can be easily transported without damaging the electronic components housed therein, which is preferred.

[0017] Specific examples of polypropylene resins include propylene homopolymers such as isotactic homopolypropylene resins and syndiotactic homopolypropylene resins obtained by homopolymerizing propylene; propylene-ethylene copolymers obtained by copolymerizing propylene with ethylene; propylene-α-olefin copolymers obtained by copolymerizing propylene with olefins having 4 or more carbon atoms, i.e., 1-butene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene, etc.; and propylene-ethylene-α-olefin copolymers obtained by copolymerizing propylene with propylene with olefins having 4 or more carbon atoms, such as 1-butene, 1-hexene, 1-heptene, 1-octene, 4-methyl-1-pentene, etc.; and propylene-ethylene-α-olefin copolymers obtained by copolymerizing propylene with propylene as the main component. Propylene copolymers may be binary or ternary or higher multi-component copolymers, and may be random copolymers, block copolymers, or reactor blended copolymers. More specifically, propylene homopolymers, propylene-ethylene copolymers, propylene-1-butene copolymers, propylene-ethylene-1-butene copolymers, propylene-4-methyl-1-pentene copolymers, propylene-3-methyl-1-pentene copolymers, propylene-ethylene-3-methyl-1-pentene copolymers, and the like. Among them, from the viewpoint of improving the stretching moldability of the porous resin layer, a crystalline homopolypropylene resin obtained by homopolymerizing propylene is preferred, and an isotactic homopolypropylene resin is more preferred.

[0018] Specific examples of polypropylene resins include polypropylene produced using a Ziegler-Natta polymerization catalyst, polypropylene produced using a metallocene polymerization catalyst (single-site polymerization catalyst), olefin-based thermoplastic elastomers also called reactor TPO, and high melt tension polypropylene, depending on the production method.

[0019] From the viewpoint of improving the mechanical strength of the porous resin layer, the melt flow rate (MFR) of the polypropylene resin according to JIS K7210:2014 (temperature 230° C., 2.16 kg load) is preferably 0.2 g / 10 min or more, more preferably 1 g / 10 min or more, and further preferably 2 g / 10 min or more. In addition, it is preferably 20 g / 10 min or less, more preferably 15 g / 10 min or less, further preferably 10 g / 10 min or less, and particularly preferably 6 g / 10 min or less.

[0020] When the porous resin layer contains polypropylene resin, it is preferably 15% by mass or more, more preferably 25% by mass or more, and further preferably 35% by mass or more. In addition, it is preferably 80% by mass or less, more preferably 70% by mass or less, and further preferably 60% by mass or less.

[0021] (Polyethylene resin) By using polyethylene resin in the porous resin layer, stretching formability can be given to the porous resin layer. In addition, for other thermoplastic resins, polyethylene resin can be used in combination. In this case, in addition to the characteristics of other thermoplastic resins, the stretching formability of polyethylene resin can also be given, so it is preferred. For example, as the resin component constituting the porous resin layer, polyethylene resin can be used in combination with polypropylene resin. Examples of the polyethylene resin that can be used include high-density polyethylene resins, medium-density polyethylene resins, linear low-density polyethylene resins, and copolymers containing ethylene as a main component.

[0022] When the porous resin layer contains a polyethylene resin, it is preferably 1% by mass or more, more preferably 3% by mass or more, and further preferably 5% by mass or more. In addition, it is preferably 20% by mass or less, more preferably 15% by mass or less, and further preferably 10% by mass or less.

[0023] When the porous resin layer contains both polypropylene resin and polyethylene resin, the mass ratio (polypropylene resin:polyethylene resin) is preferably 1:99 to 99:1, more preferably 10:90 to 97:3, and further preferably 65:35 to 95:5 from the viewpoint of pore formation.

[0024] [Particles contained in the porous resin layer] As described later, the base layer and the first surface layer included in the porous resin layer both contain particles, so the porous resin layer contains particles. By stretching the resin composition containing particles, a porous resin layer having a large number of pores formed in the layer can be easily obtained. The porous resin layer is preferably a porous stretched resin layer obtained by including particles and stretching them. The particles that can be used are not particularly limited, and for example, organic particles, inorganic particles, etc. can be enumerated. Among them, from the viewpoint of preventing the shape recovery after compression shaping, inorganic particles are preferably used. In addition, as particles, surface-treated particles can also be used.

[0025] As inorganic particles that can be used for porous resin layer, for example, calcium carbonate, titanium oxide, calcined clay, talc, barium sulfate, aluminum sulfate, silicon dioxide, zinc oxide, magnesium oxide or diatomaceous earth etc. can be cited. By coordinating inorganic particles, it is easy to form a porous resin layer with pores inside. Among them, the pore formation of the fine powder of calcium carbonate, clay or diatomaceous earth is good and economical, so it is preferred. In particular, the variety of the fine powder of calcium carbonate is rich, so it is easy to adjust the porosity, and it is easy to adjust the tone of the porous resin layer, so it is preferred.

[0026] The average particle size of the particles is preferably 0.05 μm or more, more preferably 0.1 μm or more, and further preferably 0.5 μm or more. In addition, it is preferably 6 μm or less, more preferably 4 μm or less, and further preferably 2 μm or less. If the average particle size is within the above range, it is easy to control the porosity within the desired range. The average particle size of the particles is a volume average particle size (D50) measured by a particle size distribution analyzer based on laser diffraction.

[0027] The content of particles in the porous resin layer is preferably 25 mass % or more, more preferably 30 mass % or more, and further preferably 35 mass % or more, and is preferably 80 mass % or less, more preferably 70 mass % or less, and further preferably 60 mass % or less. By making the content of the particles in the porous resin layer be more than 25 mass %, it is easy to obtain a high porosity based on the pores formed by taking the particles as the starting point during stretching, and it is easy to obtain a high shaping depth corresponding to the size of the electronic components stored. In addition, by making the content be less than 80 mass %, it is easy to maintain flexibility suitable for manufacturing and handling.

[0028] [Other additives that the porous resin layer can contain] The porous resin layer may contain additives such as a heat stabilizer (antioxidant), a light stabilizer, a conductive filler, a dispersant, and a lubricant as necessary.

[0029] When the porous resin layer contains a heat stabilizer, the heat stabilizer is generally contained in an amount of 0.001 to 1 mass %. Examples of the heat stabilizer include sterically hindered phenol-based, phosphorus-based, or amine-based heat stabilizers. When the porous resin layer contains a light stabilizer, the light stabilizer is generally contained in an amount of 0.001 to 1% by mass. Examples of the light stabilizer include sterically hindered amine-based, benzotriazole-based, and benzophenone-based light stabilizers.

[0030] The dispersant or lubricant can be used, for example, to disperse the particles. The amount of the dispersant or lubricant used in the porous resin layer is usually in the range of 0.01 to 4% by mass. Examples of the dispersant or lubricant include silane coupling agents, higher fatty acids such as oleic acid and stearic acid, metal soaps, polyacrylic acid, polymethacrylic acid, and salts thereof.

[0031] Among them, it is preferred to use a dispersant or a lubricant from the viewpoint of being able to suppress the aggregation of particles contained in the porous resin layer, increase the surface area and improve the pore formation efficiency, and easily obtain a porosity corresponding to the content even when a large amount of particles is contained. Furthermore, when a porous resin sheet including a porous resin layer is used as a carrier tape for electronic components, adhesion of dust due to static electricity can be suppressed, and thus a conductive filler can also be used.

[0032] [Properties of porous resin layer] (thickness) The thickness of the porous resin layer is 40 to 350 μm. The thickness is preferably 80 μm or more, more preferably 100 μm or more, and further preferably 120 μm or more. In addition, the thickness is preferably 300 μm or less, more preferably 250 μm or less, and further preferably 225 μm or less. The thickness of the porous resin layer can be appropriately changed within the above range according to the size of the article to be stored in the shaped pocket or the like.

[0033] If the thickness of the porous resin layer is less than 40 μm, it is difficult to ensure a sufficient depth for shaping according to the size of the receiving member. On the other hand, if the thickness of the porous resin layer exceeds 350 μm, it is difficult to maintain flexibility suitable for production and transportation.

[0034] The "thickness" of a layer in this specification refers to a value measured in accordance with JIS K7130: 1999. In the case where the porous resin layer is a multi-layer laminated structure, the value measured for the entirety of the plurality of layers is taken as the thickness of the multi-layer laminated structure. The thickness of each layer in the multi-layer laminated structure is calculated as follows: a cross section of the multi-layer laminated structure is observed using an electron microscope, the interface between the layers is determined by appearance, the thickness ratio of each layer is obtained, and the thickness of the multi-layer laminated structure obtained by the above measurement and the thickness ratio of each layer are calculated.

[0035] (Porosity) The porosity of the porous resin layer is 35 to 80%, preferably 40% or more, more preferably 45% or more, and preferably 70% or less, more preferably 60% or less. In addition, the "porosity" of a layer in this specification refers to the ratio (volume ratio) of the volume occupied by pores in the layer relative to the volume of the layer.

[0036] If the porosity is less than 35%, the porous resin layer may not be able to sufficiently follow the shape of the shape without special processes such as heating and decompression. In such a case, for example, when it is desired to shape the shape into a pocket with vertical sides and parallel bottoms relative to the surface of the porous resin sheet having the porous resin layer, it is easy to produce poor molding such as the shape of the side of the pocket becoming conical and undulating at the bottom. By making the porosity more than 35%, it is easy to perform deep shaping even without special processes such as heating and decompression. On the other hand, if the porosity exceeds 80%, sufficient mechanical strength cannot be obtained. It should be noted that the term "conformability" as used herein means that a resin deformed by shaping does not return to the state before shaping by rebounding, but can stably maintain the shape after shaping.

[0037] Examples of a method for adjusting the porosity of the porous resin layer include a method of adjusting the porosity of the entire porous resin layer by adjusting the porosity of each of the base layer, the first surface layer, and / or the second surface layer described below.

[0038] The method for measuring the porosity of the porous resin layer is not particularly limited. For example, the cross-section of the porous resin layer can be observed using an electron microscope, and the value obtained by calculating the ratio (area ratio) of the area occupied by the pores in the porous resin layer in the observation area of ​​the obtained cross-sectional photograph is obtained. In the case where the porous resin layer is a multi-layer laminated structure, the porosity of each layer is calculated, and the average value of the value obtained by weighting the porosity of each layer by thickness is taken, thereby obtaining the porosity of the entire porous resin layer.

[0039] [Layer structure of porous resin layer] The porous resin layer may be composed of only a substrate layer and a first surface layer, or may be composed of three or more layers. When the porous resin layer is composed of three or more layers, for example, a porous resin layer including a second surface layer in addition to the substrate layer and the first surface layer described later can be made.

[0040] Examples of the cross section in the stacking direction of the porous resin layer in the first embodiment include: Figure 1 In the manner shown. Figure 1 In the embodiment, the porous resin layer 10 is composed of only the base material layer 1 and the first surface layer 2 . Examples of the cross section in the stacking direction of the porous resin layer in the second embodiment include: Figure 2 In the manner shown. Figure 2 In the embodiment, the porous resin layer 10 is composed of a base material layer 1, a first surface layer 2, and a second surface layer 3. Here, the second surface layer 3 is provided on the surface of the base material layer 1 opposite to the first surface layer 2. It should be noted that the purpose of the drawings shown in this specification is to schematically show the positional relationship of each layer, pocket, etc., and its purpose is not to show the exact dimensions of the thickness of each layer, the width of the layer, the size of the pocket, etc.

[0041] The porous resin layer is not limited to the above-mentioned manner, for example, other layers can be included between the substrate layer and the first surface layer and / or the second surface layer. When the porous resin layer includes other layers, the other layers are not particularly limited as long as they have a porous structure. For example, the porosity of the other layers can be 10% or more.

[0042] <Base material layer> The porous resin layer of the porous resin sheet of the present invention includes a substrate layer. The substrate layer provides the porous resin sheet with mechanical strength required for transportation and the like, and provides space for pockets and the like when the porous resin sheet is shaped into a pocket and the like for storing electronic components. When the porous resin sheet is shaped into a pocket or the like, the pocket or the like preferably does not penetrate the substrate layer. Further, the position of the interface on the opposite side of the interface pressed down for shaping the pocket or the like in the 2 interfaces that the substrate layer has is more preferably not changed before and after the shaping of the pocket or the like.

[0043] [Material constituting base material layer] The base material layer contains a thermoplastic resin and particles. Unless otherwise specified, the material constituting the base material layer may be the same as that described for the porous resin layer, and the preferred range is also the same.

[0044] (Thermoplastic resin) The base material layer contains a thermoplastic resin. Unless otherwise specified, the preferred range of the thermoplastic resin is the same as that described for the porous resin layer.

[0045] The content of the thermoplastic resin in the substrate layer is preferably 35% by mass or more, more preferably 40% by mass or more, further preferably 45% by mass or more, particularly preferably 50% by mass or more, and most preferably 55% by mass or more. In addition, the above content is preferably 85% by mass or less, more preferably 80% by mass or less, further preferably 75% by mass or less, and particularly preferably 70% by mass or less.

[0046] (Particles) The base material layer contains particles. Unless otherwise specified, the preferred range of the particles is the same as that described for the porous resin layer.

[0047] The substrate layer contains 20% by mass or more of particles, preferably 25% by mass, more preferably 30% by mass or more. In addition, it contains 45% by mass or less, preferably less than 45% by mass, more preferably 40% by mass or less, and further preferably 35% by mass or less. If the content of the particles in the substrate layer is less than 20% by mass, the amount of pores formed by stretching decreases, resulting in difficulty in obtaining a high shaping depth corresponding to the size of the contained electronic components. In addition, if the content exceeds 45% by mass, it is difficult to maintain flexibility suitable for manufacturing and handling. In particular, it is preferred that the content of the inorganic particles be 45% by mass or less because compression of the porous resin layer due to shaping is likely to occur and shaping depth is likely to be obtained.

[0048] [Properties of the substrate layer] (thickness) The thickness of the substrate layer is preferably 35 μm or more, more preferably 70 μm or more, further preferably 90 μm or more, and particularly preferably 110 μm or more. In addition, the thickness is preferably 300 μm or less, more preferably 250 μm or less, further preferably 200 μm or less, and particularly preferably 190 μm or less. In addition, the thickness of the substrate layer is preferably greater than the thickness of any one of the first surface layer and the second surface layer described later.

[0049] The thickness of the base material layer is preferably 35 μm or more because a sufficient depth for shaping the storage member in accordance with its size can be easily obtained, and the thickness is preferably 300 μm or less because flexibility suitable for production and transportation can be easily maintained.

[0050] The thickness of the base material layer can be measured by the same method as the thickness of the porous resin layer.

[0051] (Porosity) The porosity of the substrate layer is preferably 35% or more, more preferably 40% or more, and further preferably 45% or more. The porosity is preferably 80% or less, more preferably 70% or less, and further preferably 60% or less.

[0052] By making the porosity of the substrate layer 35% or more, even in the case of a deep shape, sufficient followability to the shape can be obtained, and the shape of the bottom and side portions to be shaped is easy to stabilize, so it is preferred. In addition, by making the porosity 80% or less, it is easy to obtain the mechanical strength of the porous resin sheet, so it is preferred.

[0053] The porosity of the base material layer can be adjusted by the content of the particles in the base material layer, the average particle size, the thermoplastic resin composition, the stretching conditions, and the like.

[0054] The porosity of the base material layer can be measured by the same method as the porosity of the porous resin layer.

[0055] (Stretch) The substrate layer is preferably stretched, more preferably biaxially stretched. Since the substrate layer contains particles, it is possible to easily provide pores in the substrate layer by stretching. When the stretching is biaxial stretching, a high porosity can be obtained while suppressing the content of particles, so that even when the shape is a deep shape, the shape is easily stabilized, so it is preferred. In addition, rigidity is imparted by biaxial stretching, so even if there is a porous structure, it is not easy to cause problems in the process such as transportation, so it is preferred.

[0056] <First surface layer> The porous resin layer of the porous resin sheet of the present invention includes a first surface layer. The first surface layer is a layer located at the outermost side of the porous resin layer and located on the side of the carrier tape that is shaped into a pocket or the like. By providing the porous resin sheet with a first surface layer with a high particle content, it is easy to suppress the shape of the side of the pocket or the like during shaping from being conical.

[0057] [Material constituting the first surface layer] The first surface layer contains a thermoplastic resin and particles. Unless otherwise specified, the material constituting the first surface layer may be the same as that described for the porous resin layer, and the preferred range is also the same.

[0058] (Thermoplastic resin) The first surface layer contains a thermoplastic resin. Unless otherwise specified, the preferred range of the thermoplastic resin is the same as that described for the porous resin layer.

[0059] The content of the thermoplastic resin in the first surface layer is preferably 10% by mass or more, more preferably 20% by mass or more, and further preferably 30% by mass or more. In addition, it is preferably 50% by mass or less, more preferably 45% by mass or less, and further preferably 40% by mass or less.

[0060] By making the content of the thermoplastic resin in the first surface layer be more than 10 mass %, it is easy to suppress the fracture during molding, so it is preferred. In addition, by making the content of the thermoplastic resin be below 50 mass %, it is possible to suppress the rebound during the shaping brought by the resin, so it is preferred. Thus, for example, when it is desired to shape the surface of the porous resin sheet with vertical sides and parallel bottoms, the opportunity of the deformation of the porous resin sheet caused by fracture is easily produced, and the shape of the side of the pocket etc. during the shaping is suppressed to become a cone, and the shape of the bottom is easily stabilized, so it is preferred.

[0061] (Particles) The first surface layer contains particles. The preferred range of the particles is the same as that described for the porous resin layer unless otherwise specified.

[0062] The first surface layer contains particles more than 45 mass %, preferably contains more than 50 mass %, more preferably contains more than 55 mass %. In addition, contain below 80 mass %, preferably contain below 75 mass %, more preferably contain below 70 mass %, further preferably contain below 65 mass %.

[0063] If the content of the particle in the first surface layer is less than 45 mass %, it is difficult to control the shape of the side and bottom when shaping the shape of the pocket etc. In this regard, if the content of the particle in the first surface layer is more than 45 mass %, then for example, when you want to shape the pocket with vertical side and parallel bottom relative to the surface of the porous resin sheet, the shape of the side when being able to suppress shaping becomes conical, and the shape of the bottom is easily stabilized. This is because, at the boundary of the part of the shaping mold being pressed and the part of the shaping mold not being pressed, the interface of the particles or the particles and the thermoplastic resin is easily broken compared with the thermoplastic resin. When the particle is an inorganic particle, about the shape of the side when shaping and the shape of the bottom, the above-mentioned tendency becomes significant, so it is preferred. On the other hand, if the content of the particles exceeds 80% by mass, breakage is likely to occur during sheet molding.

[0064] [Properties of the first surface layer] (thickness) The thickness of the first surface layer is preferably 5 μm or more, more preferably 10 μm or more, further preferably 13 μm or more, particularly preferably 15 μm or more, and most preferably 18 μm or more. In addition, the thickness is preferably 50 μm or less, more preferably 40 μm or less, further preferably 35 μm or less, particularly preferably 30 μm or less, and most preferably 25 μm or less.

[0065] By making the thickness of the first surface layer 5 μm or more, the deformation of the part including the first surface layer and a part of the base layer, which is compressed by the mold to form the bottom of the pocket or the like when the shape of the pocket or the like is formed, can be averaged, and the shape of the compressed porous resin layer at the bottom of the pocket or the like is stabilized, and the shape during shaping is easily stabilized, so it is preferred. In addition, by making the thickness 50 μm or less, it is easy to shape into a deep shape, so it is preferred.

[0066] The thickness of the first surface layer can be measured by the same method as the thickness of the porous resin layer.

[0067] The ratio of the thickness of the first surface layer to the thickness of the base layer is preferably 0.03 or more, more preferably 0.05 or more, and further preferably 0.07 or more. In addition, the thickness ratio is preferably 0.5 or less, more preferably 0.3 or less, and further preferably 0.2 or less.

[0068] By making the ratio of the thickness of the first surface layer to the thickness of the substrate layer be 0.03 or more, it is not easy to rebound by the resin during shaping, and the shape is easily stabilized, so it is preferred. In addition, by making the thickness ratio be 0.5 or less, it is easy to shape into a deep shape, so it is preferred.

[0069] (Porosity) The porosity of the first surface layer is preferably 35% or more, more preferably 40% or more, and further preferably 45% or more. In addition, the porosity is preferably 80% or less, more preferably 70% or less, and further preferably 60% or less.

[0070] By making the porosity of the first surface layer more than 35%, even when the shape is deep, sufficient followability to the shape can be obtained, and the shape of the bottom and side portions of the shape is easily stabilized, so it is preferred. In addition, by making the porosity less than 80%, it is easy to obtain the mechanical strength of the sheet, so it is preferred.

[0071] The porosity of the first surface layer can be adjusted by the content of the particles in the first surface layer, the average particle size, the thermoplastic resin composition, the stretching conditions, and the like.

[0072] The porosity of the first surface layer can be measured by the same method as the porosity of the porous resin layer.

[0073] The ratio of the porosity of the first surface layer to the porosity of the substrate layer is preferably 0.80 or more, more preferably 0.85 or more, and further preferably 0.90 or more. In addition, the porosity ratio is preferably 1.20 or less, more preferably 1.15 or less, and further preferably 1.10 or less.

[0074] By making the ratio of the porosity of the first surface layer to the porosity of the substrate layer within the above-mentioned range, the difference between the shape of the surface layer formed by shaping and the shape of the substrate layer is suppressed. When it is desired to form a shape such as a pocket having sides perpendicular to the surface of the porous resin sheet and a bottom parallel to the bottom, the shape of the side of the pocket etc. can be suppressed from becoming conical, which is preferred.

[0075] (Stretch) The first surface layer is preferably stretched, more preferably uniaxially stretched. Orienting the resin chains in the stretching direction facilitates breaking along the stretching direction during shaping, and the shape formed by shaping along the stretching direction can be stabilized, which is preferred. In addition, since the first surface layer contains particles, long pores are formed in the stretching direction by uniaxially stretching the first surface layer, and the fracture along the stretching direction becomes easier during shaping, and the shape formed by shaping along the stretching direction can be stabilized, so it is preferred. In particular, when shaping into a shape such as a pocket with a long side direction parallel to the stretching direction, the pores extending in the stretching direction are easy to correspond to shaping, which is advantageous.

[0076] In this specification, "the long side direction of a pocket or the like" refers to the direction of the long axis side of a pocket or the like of any shape whose aspect ratio is not 1:1. In addition, "the short side direction of a pocket or the like" refers to the direction of the short axis side of a pocket or the like of any shape whose aspect ratio is not 1:1.

[0077] Since both the first surface layer and the substrate layer contain particles, it is preferred that the first surface layer is uniaxially stretched and the substrate layer is biaxially stretched. Thus, a porous resin layer can be made in which the first surface layer is a porous uniaxially stretched resin layer and the substrate layer is a porous biaxially stretched resin layer.

[0078] By making such a layer structure, when you want to shape a pocket or the like with sides perpendicular to the surface of the porous resin sheet and a bottom parallel to the surface, it is possible to suppress molding defects such as the side shape of the pocket or the like becoming conical or producing undulations at the bottom, so it is preferred.

[0079] The porous resin layer in which the first surface layer is a porous uniaxially stretched resin layer and the base layer is a porous biaxially stretched resin layer can be produced through the following steps, for example. Step 1: A porous uniaxially stretched resin layer is obtained by uniaxially stretching a resin sheet for forming a base layer. Step 2: A resin sheet for forming a first surface layer is laminated on the porous uniaxially stretched resin layer obtained in step 1 to obtain a laminated sheet. Step 3: The laminated sheet obtained in step 2 is uniaxially stretched in a direction perpendicular to the stretching direction in step 1 to obtain a porous resin layer in which the first surface layer is a porous uniaxially stretched resin layer and the base layer is a porous biaxially stretched resin layer.

[0080] <Second surface layer> The porous resin layer of the porous resin sheet of the present invention can further include a second surface layer on the surface of the substrate layer on the opposite side of the first surface layer. The second surface layer is the outermost layer located in the porous resin layer, and when the porous resin sheet of the present invention is shaped into a shape such as a pocket, it is located on the opposite side of the surface shaped into the shape. It is preferred that the porous resin layer includes the second surface layer because the bottom of the shaped shape is stabilized.

[0081] [Material constituting the second surface layer] Unless otherwise specified, the material constituting the second surface layer may be the same material as that described for the porous resin layer, and the preferred range is also the same.

[0082] (Particles) The second surface layer can contain particles. The preferred range of the particles is the same as that described for the porous resin layer unless otherwise specified.

[0083] When the second surface layer contains particles, preferably contain more than 40 mass %, more preferably contain more than 45 mass %, further preferably contain more than 50 mass %, particularly preferably contain more than 55 mass %. In addition, preferably contain below 80 mass %, more preferably contain below 75 mass %, further preferably contain below 70 mass %, particularly preferably contain below 65 mass %. The content of the particles in the second surface layer is preferably 40% by mass or more, because pores are easily developed by stretching, and preferably 80% by mass or less, because the breaking strength of the film can be maintained.

[0084] [Properties of the second surface layer] (thickness) The thickness of the second surface layer is preferably 5 μm or more, more preferably 7 μm or more, and further preferably 10 μm or more. Also, the thickness is preferably 50 μm or less, more preferably 40 μm or less, and further preferably 30 μm or less.

[0085] The second surface layer preferably has a thickness of 5 μm or more because it serves as a receiving layer for the first surface layer or the base material layer formed by the compression-shaped portion being compressed.

[0086] The thickness of the second surface layer can be measured by the same method as the thickness of the porous resin layer.

[0087] (Porosity) The porosity of the second surface layer is preferably 35% or more, more preferably 40% or more, and further preferably 45% or more. In addition, the porosity is preferably 80% or less, more preferably 70% or less, and further preferably 60% or less.

[0088] By making the porosity of the first surface layer more than 35%, even when the shape is deep, sufficient followability to the shape can be obtained, and the shape of the bottom and side portions of the shape is easily stabilized, so it is preferred. In addition, by making the porosity less than 80%, it is easy to obtain the mechanical strength of the porous resin sheet, so it is preferred.

[0089] The porosity of the second surface layer can be adjusted by the content of the particles in the first surface layer, the average particle size, the thermoplastic resin composition, the stretching conditions, and the like.

[0090] The porosity of the second surface layer can be measured by the same method as the porosity of the porous resin layer.

[0091] (Stretch) The second surface layer is preferably stretched, more preferably uniaxially stretched. By uniaxially stretching the second surface layer, the mechanical strength in the uniaxial direction is improved, and thus, shape stability after being formed into a shape such as a pocket is easily obtained, which is preferred.

[0092] The porous resin layer in which the first surface layer and the second surface layer are porous uniaxially stretched resin layers and the base layer is a porous biaxially stretched resin layer can be produced, for example, through the following steps. Step 1: A porous uniaxially stretched resin layer is obtained by uniaxially stretching a resin sheet for forming a base layer. Step 2: A resin sheet for forming a first surface layer is laminated on the porous uniaxially stretched resin layer obtained in step 1, and a resin sheet for forming a second surface layer is laminated on the surface of the porous uniaxially stretched resin layer on the opposite side of the resin sheet for forming the first surface layer to obtain a laminated sheet. Step 3: The laminated sheet obtained in step 2 is uniaxially stretched in a direction perpendicular to the stretching direction in step 1 to obtain a porous resin layer in which the first and second surface layers are porous uniaxially stretched resin layers and the base layer is a porous biaxially stretched resin layer.

[0093] (Method for producing porous resin layer, base material layer, first surface layer and second surface layer) The manufacture method of porous resin layer, substrate layer, first surface layer and second surface layer is not particularly limited, and can be manufactured by common methods. For example, T-type die, I-type die etc. connected on screw type extruder can be enumerated, molten resin is extruded into sheet-like casting, calendaring (calendar molding), calendaring or inflation molding etc. In the case of manufacturing the porous resin layer of multi-layer laminated structure, after substrate layer, first surface layer and / or second surface layer are manufactured respectively, stacking is carried out by stacking lamination mode etc. In addition, it is also possible to use the common methods such as multi-layer die mode using feed block, multi-manifold or extrusion lamination mode using multiple molds, film forming and stacking of each layer are carried out simultaneously.

[0094] A porous resin sheet can be produced by laminating the porous resin layer and other layers as necessary. When porous resin layer, substrate layer, first surface layer and / or second surface layer are stretched, substrate layer can be stretched before laminating first surface layer and / or second surface layer, and can be stretched after laminating.As a mode, the porous resin layer that the first surface layer and / or second surface layer are porous uniaxial stretching resin layer, substrate layer are porous biaxial stretching resin layer, for example, can be manufactured through the above-mentioned process.

[0095] Examples of stretching methods include longitudinal stretching using a roller group peripheral speed difference, transverse stretching using a tenter furnace, sequential biaxial stretching using a combination of these methods, rolling, simultaneous biaxial stretching using a combination of a tenter furnace and a pantograph, and simultaneous biaxial stretching using a combination of a tenter furnace and a linear motor. In addition, after the molten resin is extruded into a tube using a circular die head connected to a screw extruder, a simultaneous biaxial stretching (inflation molding) method by blowing air can also be used.

[0096] Wherein, porous resin layer, substrate layer, first surface layer and second surface layer are by extrude resin combination into sheet from the T-type die connected with extruder, then this sheet is stretched and manufactured, easily realize multilayer or adjust film thickness, therefore preferably.As stretching method, can enumerate longitudinal stretching method, transverse stretching method, the successive biaxial stretching method or the biaxial stretching method simultaneously of their combination.

[0097] When the thermoplastic resin used is an amorphous resin, the stretching temperature during stretching is preferably in the range of above the glass transition temperature of the thermoplastic resin. In addition, when the thermoplastic resin is a crystalline resin, the stretching temperature is preferably in the range of above the glass transition temperature of the amorphous part of the thermoplastic resin and below the melting point of the crystalline part of the thermoplastic resin, and is preferably a temperature 2 to 60°C lower than the melting point of the thermoplastic resin. Specifically, in the case of a propylene homopolymer (melting point 155 to 167°C), a stretching temperature of 100 to 164°C is preferred, and in the case of a high-density polyethylene resin (melting point 121 to 134°C), a stretching temperature of 70 to 133°C is preferred. In particular, from the viewpoint of obtaining a higher porosity, the stretching temperature when the thermoplastic resin is a crystalline resin is preferably 20°C or more lower than the melting point of the thermoplastic resin, and more preferably 25°C or more lower. The stretching temperature can be set according to the glass transition temperature or melting point of the thermoplastic resin mainly used (for example, the thermoplastic resin used in an amount of 50% by mass or more in the entire thermoplastic resin).

[0098] The stretching speed is not particularly limited, but is preferably within a range of 20 to 350 m / min from the viewpoint of stable stretch molding.

[0099] In addition, about the stretch ratio, it can also be appropriately determined by considering the characteristics of the thermoplastic resin used. For example, when using a propylene homopolymer or a propylene copolymer, the lower limit of the stretch ratio when stretched in one direction is usually more than 1.1 times, preferably more than 2 times, and the upper limit is less than 10 times, preferably less than 9 times. On the other hand, the stretch ratio during biaxial stretching, in terms of area stretch ratio, is usually more than 1.5 times, preferably more than 4 times, and the upper limit is less than 75 times, preferably less than 50 times. In the case of stretching other thermoplastic resin films in one direction, the lower limit of the stretch ratio is usually more than 1.2 times, preferably more than 2 times, and the upper limit is less than 10 times, preferably less than 5 times. The stretch ratio during biaxial stretching, in terms of area stretch ratio, is usually more than 1.5 times, preferably more than 4 times, and the upper limit is less than 20 times, preferably less than 12 times. If it is within the range of the above-mentioned stretch ratio, it is easy to obtain the target porosity and unit area weight, and opacity is easily improved. In addition, it is not easy to cause the breakage of the film, and stretch molding is easily stabilized. When the pores in the porous resin layer are formed by stretching from particles as starting points, in order to make the porous resin layer have a high porosity, it is preferred that the stretching ratio, stretching temperature, particle content, etc. all satisfy the above-mentioned specific conditions.

[0100] <Porous resin sheet> The porous resin sheet of the present invention includes the above-mentioned porous resin layer.

[0101] [Properties of porous resin sheet] (Breaking Strength) The breaking strength of the porous resin sheet in the width direction is preferably 0.1 kgf / mm 2 More preferably 1.0 kgf / mm 2 More preferably, 2.0 kgf / mm 2 In addition, the breaking strength in the width direction is preferably 10 kgf / mm 2 Below, more preferably 8kgf / mm 2 Below, more preferably 6kgf / mm 2 the following. Here, “breaking strength of the porous resin sheet in the width direction” refers to the breaking strength measured by stretching the porous resin sheet in the width direction (TD direction). The breaking strength can be measured according to JIS-K7127:1999, for example.

[0102] By setting the breaking strength of the porous resin sheet in the width direction to 0.1 kgf / mm 2 The above is preferred from the viewpoint of maintaining the film shape during transportation. In addition, by making the breaking strength in the width direction 10 kgf / mm 2 The following are preferred from the viewpoint of maintaining the shape during compression shaping.

[0103] In order to increase the number of pockets per unit length of the carrier tape, the length direction of the pockets is usually parallel to the width direction of the carrier tape. Therefore, it is preferable to design the porous resin sheet to have the above-mentioned breaking strength in the width direction. In addition, when the longitudinal direction of the pocket or the like is formed to be parallel to the longitudinal direction of the carrier tape, the porous resin sheet can also be designed to have the above-mentioned breaking strength in the longitudinal direction.

[0104] [use] The porous resin sheet of the present invention has suitable properties for forming a carrier tape. Therefore, the porous resin sheet of the present invention is preferably used for a carrier tape.

[0105] For example, a carrier tape including the above-mentioned porous resin sheet and a pocket formed in the porous resin sheet can be prepared. The size of the pocket can be, for example, 0.1 mm×0.1 mm to 3 mm×3 mm in vertical dimension×horizontal dimension.

[0106] Examples of a cross section in the lamination direction passing through the pocket of a carrier tape using one embodiment of the porous resin sheet of the present invention include: Figure 4 As shown. Figure 4As shown, the pocket 4 preferably does not penetrate the base material layer 1. Furthermore, of the two interfaces 1a and 1b of the base material layer 1, the position of the interface 1b on the side opposite to the interface 1a on the side pressed down to form the pocket 4 preferably does not change before and after forming the pocket 4. On the other hand, the interface 1a on the side of the carrier tape formed into a shape such as a pocket is preferably linear or substantially linear in the cross section passing through the pocket of the carrier tape.

[0107] The carrier tape using the porous resin sheet of the present invention may further include other necessary components such as a cover tape.

[0108] The carrier tape formed of the porous resin sheet of the present invention can be suitably used as a carrier tape for storing components. Examples of the components include electronic components.

[0109] <Method for forming porous resin sheet> There is no particular limitation on the method for shaping the porous resin sheet into a shape such as a pocket, and examples thereof include pressure molding, press molding, vacuum rotation molding, etc. Among them, from the viewpoint of cost, it is preferred to shape the porous resin sheet by press molding at room temperature.

[0110] The shape of the porous resin sheet is selected according to the shape of the member to be housed and is not particularly limited. Examples of the shape include cylindrical shapes and prism shapes. Example

[0111] Hereinafter, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to the following Examples.

[0112] <Resin composition> Table 1 shows the materials and compounding ratios of the resin compositions used in Examples and Comparative Examples.

[0113] [Table 1]

[0114] <Porous resin sheet> [Example 1] After mixing the resin composition A with an extruder set at 230°C, the resin composition A was supplied to an extrusion die set at 250°C, extruded into a sheet, and cooled by a cooling device to obtain an unstretched sheet. The unstretched sheet was heated to 130°C, and stretched 4 times in the longitudinal direction (length direction) using multiple roller groups with different peripheral speed differences to obtain a 4-fold stretched film. Next, after mixing the resin composition C with an extruder set at 250°C, the resin composition C was supplied to an extrusion die set at 250°C, extruded into a sheet, and laminated on the surface of the 4-fold stretched film adjusted above to obtain a laminated film with a 2-layer structure. Next, the laminated film was cooled to 60°C, heated again to about 140°C using a tentering furnace, stretched 8 times in the transverse direction (width direction), and annealed in an oven adjusted to 160°C. After cooling to 60°C, the edges were cut off to obtain a porous resin sheet with a thickness of 200 μm and a porosity of 48.3% with a two-layer structure (first surface layer / substrate layer; composition: resin composition C / resin composition A, porosity: 40.0% / 49.0%, thickness: 15 μm / 185 μm, stretching: uniaxial / biaxial).

[0115] In addition, the measurement of the properties of the obtained porous resin sheet was performed as follows. (Overall Thickness) The entire thickness (μm) of the porous resin sheet was measured using a constant pressure thickness meter (machine name: PG-01J, manufactured by TECLOCK) in accordance with JIS K7130: 1999 "Plastics - Films and sheets - Thickness measurement method".

[0116] (Thickness of each layer) The thickness (μm) of each layer in the multilayer laminate structure was measured as follows. The porous resin sheet was cooled to a temperature below -60°C using liquid nitrogen, and a razor blade (trade name: Proline Blade, manufactured by Schick Japan Co., Ltd.) was used to cut the sample at a right angle to the sample placed on the glass plate to prepare a sample for measuring the cross section. The cross section of the sample was observed using a scanning electron microscope (machine name: JSM-6490, manufactured by JEOL Ltd.), and the boundary lines of each layer were determined based on the composition appearance to determine the thickness ratio of each layer in the porous resin sheet. The thickness of each layer was obtained by multiplying the total thickness measured above by the thickness ratio of each layer.

[0117] (Determination of Porosity) The porosity (%) of each layer in the multilayer laminate structure was measured as follows. Cut any part of the porous resin sheet, embed it with epoxy resin and solidify it, and then use a slicer to cut it perpendicularly to the surface direction and TD direction of the porous resin sheet of the object to be measured, and attach it to the observation sample stage in such a way that the cut surface becomes the observation surface. Gold or gold-palladium, etc. are evaporated on the observation surface, and the cut surface of the porous resin sheet is observed at any magnification that is easy to observe using a scanning electron microscope (for example, a magnification of 500 times to 3000 times), and the observed area is read as image data. The image data obtained is processed by an image analysis device to obtain the area ratio (%) of the pore part in each layer of the porous resin sheet, and the average value of the area ratio (%) obtained at any 10 or more locations is used as the porosity (%) of each layer. The porosity of all the layers was obtained by averaging the values ​​obtained by weighting the porosity of each layer by the thickness.

[0118] [Example 2], [Comparative Example 1], [Comparative Example 4] Porous resin sheets of Example 2, Comparative Example 1 and Comparative Example 4 were obtained by the same method as in Example 1 except that the resin composition, the thickness of each layer and the porosity of each layer were changed as shown in Table 2 or Table 3.

[0119] [Example 3] A porous resin sheet of Example 3 was obtained by the same method as in Example 1 except that the stretching temperature in the transverse direction (temperature of the tenter furnace) was changed to 145°C.

[0120] [Example 4] A porous resin sheet of Example 4 was obtained by the same method as in Example 1 except that the stretching temperature in the longitudinal direction was changed to 140°C.

[0121] [Comparative Example 2] A porous resin sheet of Comparative Example 2 was obtained by the same method as in Example 2 except that the stretching temperature in the longitudinal direction was changed to 145°C.

[0122] [Table 2] Table 2

[0123] [Example 5] A porous resin sheet of Example 5 was obtained by the same method as in Example 1 except that the resin composition was changed as shown in Table 3 and the stretching temperature in the transverse direction (temperature of the tenter furnace) was changed to 135°C.

[0124] [Comparative Example 3] After mixing the resin composition B in an extruder set at 230°C, the mixture was supplied to a feed block multilayer die set at 250°C and extruded into a sheet. The sheet was cooled by a cooling device to obtain an unstretched sheet. The unstretched sheet was heated to 135°C and stretched 4 times in the longitudinal direction to obtain a 4-fold stretched film. Next, the 4-fold stretched film was cooled to 60°C, heated again to about 135°C using a tentering furnace, stretched 8 times in the transverse direction, and then annealed in an oven adjusted to 160°C. After cooling to 60°C, the edges were cut off to obtain a 4-fold stretched film. Figure 3 The single-layer structure shown (substrate layer; composition: resin composition B, porosity: 50.0%, thickness: 200 μm, stretching: biaxial) gave a porous resin sheet having a total thickness of 200 μm and a porosity of 50.0%.

[0125] [Example 6] After the resin composition A is kneaded by an extruder set at 230°C, it is supplied to an extrusion die set at 250°C, extruded into a sheet, and cooled by a cooling device to obtain an unstretched sheet. The unstretched sheet is heated to 135°C, and stretched 4 times in the longitudinal direction using multiple roller groups with different peripheral speed differences to obtain a 4-fold stretched film. Next, the resin composition C is kneaded by an extruder set at 250°C, supplied to an extrusion die set at 250°C, extruded into a sheet, and laminated on the surface and back of the above-adjusted 4-fold stretched film to obtain a laminated film with a 3-layer structure. Next, the laminated film was cooled to 60°C, heated again to about 135°C using a tentering furnace, stretched 8 times in the transverse direction, annealed in an oven adjusted to 160°C, cooled to 60°C, and the edges were cut off to obtain a porous resin sheet with a thickness of 200 μm and a porosity of 49.2% with a three-layer structure (first surface layer / substrate layer / second surface layer; composition: resin composition C / resin composition A / resin composition C, porosity: 40.0% / 50.0% / 40.0%, thickness: 15 μm / 170 μm / 15 μm, stretching: uniaxial / biaxial / uniaxial).

[0126] [Example 7] A porous resin sheet of Example 7 was obtained by the same method as in Example 1 except that the resin composition A and the resin composition C were extruded into sheets so that the thickness of the substrate layer was 190 μm and the thickness of the first surface layer was 10 μm.

[0127] [Example 8] A porous resin sheet of Example 8 was obtained by the same method as in Example 1 except that the resin composition A and the resin composition C were extruded into sheets so that the thickness of the substrate layer was 195 μm and the thickness of the first surface layer was 5 μm.

[0128] [Example 9] A porous resin sheet of Example 9 was obtained by the same method as in Example 1 except that the resin composition was changed as shown in Table 3 and the stretching temperature in the transverse direction (temperature of the tenter furnace) was changed to 150°C.

[0129] [Example 10] A porous resin sheet of Example 3 was obtained by the same method as in Example 1 except that the stretching temperature in the transverse direction (temperature of the tenter furnace) was changed to 130°C.

[0130] [Table 3]

[0131] <Evaluation of porous resin sheet> The porous resin sheets obtained in the above-mentioned Examples and Comparative Examples were evaluated in the following manner. The results are shown in Tables 4 and 5.

[0132] [Breaking strength] The stress at break of the sheet in the width direction was measured in accordance with JIS-K7127:1999 (Plastics-Testing methods for tensile properties). Test piece size: 15mm×150mm Stretching speed: 300mm / min. The same sample was measured three times and the average value was calculated.

[0133] [Shapeability] Using a metal plate for deboss processing (front end: 400μm×200μm rectangle, blade angle: 90°) manufactured by Tsukaya Blade Manufacturing Co., Ltd., using a press (small test press manufactured by Toyo Seiki Co., Ltd.), from the first surface layer of the porous resin sheet obtained in each of the above embodiments and comparative examples to the substrate layer, under the pressing conditions of 1MPa / 10sec. / normal temperature, a pseudo-pocket shape with a longitudinal dimension of 400μm, a lateral dimension of 200μm, and a depth of 90% of the thickness of the sheet was formed. The cross section of the pseudo-pocket portion was cut with a razor blade, and the cross-sectional shape was observed using a digital microscope (HRX-01 manufactured by Hirox Co., Ltd.), and evaluated as shown below.

[0134] (depth) Evaluation was performed as shown below. A: Very good The depth can reach 30 μm or more, and the shaping can be performed to a depth exceeding 85% and within 90% of the sheet thickness. B: Good The depth can reach 30 μm or more, and the shaping can be performed to a depth exceeding 80% and within 85% of the sheet thickness. C: No problem level The depth can reach 30 μm or more, and the shaping can be performed to a depth exceeding 75% and within 80% of the sheet thickness. D: Poor Although it is possible to achieve a depth of 30 μm or more, it is not possible to form a shape to a depth exceeding 75% of the sheet thickness. E: Very bad It is not possible to reach a depth of more than 30 μm.

[0135] (Conical Inhibition) Evaluation was performed as shown below. A: Very good The angle between the bottom surface and the side surface is greater than 85°. B: Good The angle between the bottom surface and the side surface is greater than or equal to 80° and less than 85°. C: No problem level The angle between the bottom surface and the side surface is greater than or equal to 75° and less than 80°. D: Poor The angle between the bottom surface and the side surface is greater than or equal to 60° and less than 75°. E: Very bad The angle between the bottom surface and the side surface is less than 60°.

[0136] (Bottom stability) The distance between the bottom of the shaped pocket and the surface of the porous resin sheet opposite to the first surface layer is measured by the cross-sectional image. For 10 pockets, the maximum and minimum values ​​of the distance are recorded, and the average value of the difference is calculated. The bottom stability is evaluated as shown below according to the average value. A: Very good (average value is less than 1 μm) B: Good (average value is more than 1 μm and less than 3 μm) C: No problem (average value is more than 3 μm and less than 5 μm) D: Poor (average value is more than 5 μm and less than 10 μm) E: Very poor (average value is more than 10 μm)

[0137] [Table 4] Table 4

[0138] [Table 5]

[0139] As can be seen from Examples 1 to 10, the porous resin sheet of the present invention shows good breaking strength and shapeability even if the balance of thickness, porosity, stretching mode and layer structure are changed within a specified range. In addition, as can be seen from Examples 1, 7 and 8, the greater the thickness of the first surface layer, the greater the bottom stability. Further, as can be seen from Examples 9 and 10, by increasing the content of particles in the first surface layer and / or reducing the stretching temperature of the first surface layer, the porosity of the first surface layer becomes higher, thereby improving the shapeability. In contrast, the thickness of the porous resin sheet of Comparative Example 1 is insufficient, so it is impossible to perform sufficient depth shaping. The porosity of the porous resin sheet of Comparative Example 2 is low, so the shaping property is poor in terms of cone suppression and bottom stability. The porous resin sheet of Comparative Example 3 is composed only of a substrate layer, so the shaping property is poor in terms of taper suppression. The content of particles in the first surface layer of the porous resin sheet of Comparative Example 4 is insufficient, so the shaping property is poor in terms of cone suppression and bottom stability.

[0140] In the above, various embodiments are described with reference to the accompanying drawings, but the present invention is certainly not limited to the above examples. Obviously, those skilled in the art can think of various variations or modifications within the scope of the claims, and it should be understood that these also belong to the technical scope of the present invention. In addition, the various components in the above embodiments may also be arbitrarily combined within the scope of the gist of the invention.

[0141] It should be noted that the present application is based on the Japanese patent application (Japanese Patent Application No. 2022-102194) filed on June 24, 2022, the contents of which are incorporated herein by reference. Industrial Applicability

[0142] The porous resin sheet of the present invention can be suitably used, for example, as a porous resin sheet for a carrier tape. Description of Reference Numerals

[0143] 1. Substrate layer 2 First surface layer 3 Second surface layer 4 pockets 10. Porous resin layer.

Claims

1. A porous resin sheet, It is characterized in that comprising a porous resin layer containing a thermoplastic resin, The thickness of the porous resin layer is 40 to 350 μm. The porosity of the porous resin layer is 35-80%. The porous resin layer comprises a substrate layer and a first surface layer, The substrate layer and the first surface layer both contain thermoplastic resin and particles, The content of the particles in the substrate layer is 20 to 45% by mass. The content of the particles in the first surface layer is 45 to 80% by mass.

2. The porous resin sheet according to claim 1, in, The first surface layer is a porous uniaxially stretched resin layer, The substrate layer is a porous biaxially stretched resin layer.

3. The porous resin sheet according to claim 1 or 2, in, The first surface layer has a thickness of 5 μm or more.

4. The porous resin sheet according to claim 1 or 2, in, The first surface layer has a thickness of 10 μm or more.

5. The porous resin sheet according to claim 1 or 2, in, The porous resin layer further includes a second surface layer on a surface of the base material layer opposite to the first surface layer.

6. The porous resin sheet according to claim 1 or 2, in, The ratio of the porosity of the first surface layer to the porosity of the base layer is 0.80 to 1.

20.

7. The porous resin sheet according to claim 1 or 2, in, The breaking strength of the porous resin sheet in the width direction is 0.1 to 10 kgf / mm 2 .

8. The porous resin sheet according to claim 1 or 2, in, The porous resin sheet is used for a carrier tape.

9. A carrier tape, It is characterized in that A method comprising: a porous resin sheet according to claim 1 or 2; and Pockets are formed in the porous resin sheet.

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