Laminated sheet material and its manufacturing method

Abstract

The present invention provides: a multilayer sheet material which exhibits high flexibility in the thickness direction, while having high productivity; and a method for producing this multilayer sheet material. This multilayer sheet material is provided with a resin sheet material, a foam layer that is superposed on the resin sheet material, and a skin layer that is superposed so as to be adjacent to the foam layer; the skin layer and the foam layer comprise a base material resin that contains a thermoplastic resin; the foam layer comprises an internal space that is formed between the resin sheet material and the skin layer, and a plurality of column parts that extend from the skin layer to the resin sheet material in the thickness direction; and the area ratio of the cross-sections of the column parts in a cross-section of the foam layer, the cross-section being perpendicular to the thickness direction, is 10% to 60%.

Description

[Technical field]

[0001] The present disclosure relates to laminated sheet materials and methods for making same. [Background technology]

[0002] Laminated resin sheets have a wide range of applications, such as exterior materials for various industrial products, interior materials for automobiles, sound absorbing materials, heat insulating materials, cushions, and even surface materials for applications that reproduce a specific tactile sensation, such as artificial skin. In particular, laminated resin sheets having foamed layers, such as foams or foam sheets, are useful because they are excellent in tactile sensation, sound absorbing properties, heat insulating properties, flexibility, and the like.

[0003] JP 2022-105688 A (Patent Document 1) discloses a method for manufacturing a foam laminate sheet. This method for manufacturing a foam laminate sheet includes a lamination step of laminating a plurality of foam sheets to form a laminate, and a thermocompression step of thermocompressing the laminate at a temperature equal to or higher than the softening point and equal to or lower than the melting point of the plurality of foam sheets constituting the laminate. In this method for manufacturing a foam laminate sheet, when the foam sheet raw material is a foam sheet having a skin layer on both surfaces, it may include a step of dividing the foam sheet raw material into two foam sheets having a skin layer only on one surface, or a step of dividing the foam sheet into two foam sheets having a skin layer only on one surface and one or more foam sheets having no skin layer. In Patent Document 1, a foam sheet is usually formed with a bubble-free skin layer on both surfaces of the sheet in the process of forming a composition that is a raw material for a foam into a sheet, but it has been pointed out that this skin layer is hard due to its high density, which leads to a decrease in cushioning properties and ability to follow fine irregularities. Due to this problem, it has been disclosed that in order to ensure cushioning properties and ability to conform to uneven surfaces, the skin layer may be divided and removed by splitting or the like, and only the core portion without the skin layer may be used as a foamed sheet.

[0004] JP 2021-053945 A (Patent Document 2) discloses a method and an apparatus for manufacturing a foamed resin molded product. In this method for manufacturing a foamed resin molded product, a so-called core-back method is used in which a cavity formed on the separation surface between a first mold and a second mold is filled with a foamed resin, and then the volume of the cavity is increased to foam the foamed resin. Patent Document 2 describes that the core-back method is known as a method for molding a foamed resin molded product by filling a resin layer containing a foaming agent into a mold with a variable cavity volume. In addition, in this core-back method, the foamed resin filled in the mold is cooled from the contact surface with the mold to form a skin layer, and then the volume in the cavity is expanded when the temperature of the foamed resin in the cavity reaches an appropriate temperature, thereby forming a core layer with a bubble structure inside the skin layer.

[0005] Japanese Patent Application Laid-Open No. 2021-187039 (Patent Document 3) discloses a method for molding a foamed resin sheet. This method for molding a foamed resin sheet employs core-back molding, in which the mold is retracted after shaping to expand the mold space.

[0006] Specifically, in this foamed resin sheet molding method, the foamed resin sheet in a molten state is sandwiched between a pair of dies, each of the dies is brought into contact with the foamed resin sheet, and then, after a predetermined time has elapsed, each of the dies is retracted while vacuum suction is applied. Alternatively, in this foamed resin sheet molding method, the foamed resin sheet in a molten state is sandwiched between a pair of dies, each of the dies is brought into contact with the foamed resin sheet, and then, after the surface of the foamed resin sheet is hardened, each of the dies is retracted while vacuum suction is applied. In this way, in this foamed resin sheet molding method, the foamed resin sheet in a molten state is sandwiched between a pair of dies, each of the dies is brought into contact with the foamed resin sheet, and then, the core-back is not performed immediately, but is performed after a predetermined time has elapsed. Therefore, after the dies are brought into contact with the foamed resin sheet, the temperature of the surface of the foamed resin sheet decreases with the passage of time, the surface is hardened, and a so-called skin layer is formed. In this state, the foamed resin sheet and the dies are kept in close contact with each other by vacuum suction, and the bubbles of the foamed resin sheet are sufficiently expanded by the core-back, and the wall thickness is also sufficiently expanded. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] JP 2022-105688 A [Patent Document 2] Patent Publication No. 2021-053945 [Patent Document 3] JP 2021-187039 A Summary of the Invention [Problem to be solved by the invention]

[0008] In the production of a foam or foam sheet (hereinafter sometimes referred to as a foam, etc.), when a core-back method as described in Patent Documents 2 and 3 is used, a skin layer may be formed on both sides of the foam, etc. In the production method of a foam laminate sheet as disclosed in Patent Document 1, a step of laminating a foam after production is required, which reduces productivity. In addition, depending on the desired touch and flexibility (particularly the touch and flexibility in the thickness direction), it is necessary to remove a skin layer from the foam, etc., which reduces productivity. Therefore, it is desired to provide a laminate sheet material that is highly flexible in the thickness direction and highly productive, and a production method thereof.

[0009] The present disclosure has been made in consideration of the above-mentioned circumstances, and has an object to provide a laminated sheet material that is highly flexible in the thickness direction and highly productive, and a manufacturing method thereof. [Means for solving the problem]

[0010] In order to achieve the above object, the laminated sheet material according to the present disclosure comprises: A resin sheet material; A foam layer laminated on the resin sheet material; a skin layer laminated adjacent to the foam layer, The base resin of the skin layer and the foam layer contains a thermoplastic resin, The foam layer is An internal space formed between the resin sheet and the skin layer; A plurality of column portions extending from the skin layer to the resin sheet along a thickness direction, In a cross section perpendicular to the thickness direction of the foamed layer, the cross-sectional area ratio of the column portion is 10% or more and 60% or less.

[0011] In order to achieve the above object, the present disclosure provides a method for producing the laminated sheet material described above, A melting step of melting a base resin containing a thermoplastic resin; an impregnation step of impregnating the base resin with a supercritical fluid of carbon dioxide or nitrogen to obtain a foamable base resin; and a molding step of injecting the foamable base resin into a mold in which a resin sheet material has been set in advance, and molding the resin by a core-back molding method.

[0012] In order to achieve the above object, a method for producing a laminated sheet material according to the present disclosure includes: A melting step of melting a base resin containing a thermoplastic resin; an impregnation step of impregnating the base resin with a supercritical fluid of carbon dioxide or nitrogen to obtain a foamable base resin; A molding step of injecting the foamable base resin into a mold in which a resin sheet material has been set in advance, and molding the foamable base resin by a core-back molding method, the base resin includes filler particles having a surface that is poorly compatible with the thermoplastic resin; The content of the filler particles in the base resin is 0.5% by mass or more and 30% by mass or less, The filler particles have an average particle size on a volume basis of 5 μm or more and 100 μm or less. Effect of the Invention

[0013] According to the present disclosure, it is possible to provide a laminated sheet material that is highly flexible in the thickness direction and has high productivity, and a method for manufacturing the same. [Brief description of the drawings]

[0014] [Figure 1] FIG. 2 is a cross-sectional view of the laminated sheet material according to the embodiment. [Diagram 2] FIG. 2 is an explanatory diagram of an injection molding apparatus for implementing the manufacturing method according to the present embodiment. [Diagram 3] FIG. 4 is an explanatory diagram of a dispersion state of filler particles in a base resin in a base layer. [Figure 4] FIG. 2 is an explanatory diagram of the structure of a filler particle. [Diagram 5] FIG. 2 is a cross-sectional view illustrating a structure of a mold. [Figure 6] FIG. 11 is an explanatory view of a state in which the second mold is relatively separated from the first mold. [Figure 7] FIG. 13 is an explanatory diagram of a state in which a resin sheet material is set in a mold. [Figure 8] FIG. 2 is an explanatory diagram of the state immediately after a foamable base resin is supplied to a mold. [Figure 9] FIG. 2 is an explanatory diagram of a state in which a mold to which a foamable base resin has been supplied is in a core-back state. [Figure 10] 1 is an image of a cross section of a laminated sheet material observed with an optical microscope. [Figure 11] 11 is an image of the cross section taken along line XI-XI in FIG. 10, observed with an optical microscope. [Figure 12] This is an image obtained by performing mapping processing on the image shown in FIG. [Figure 13] FIG. 2 is an explanatory diagram (cross-sectional view) of the structure of a column portion in a foam layer. [Figure 14] FIG. 4 is an explanatory diagram (cross-sectional view) of a state in which a column portion of a foam layer is bent. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] A laminated sheet material and a manufacturing method thereof according to an embodiment of the present disclosure will be described with reference to the drawings.

[0016] 1 shows a cross-sectional view of a laminated sheet material 100 according to this embodiment. First, an overview of the laminated sheet material 100 and a method for manufacturing the same will be described.

[0017] The laminated sheet material 100 according to this embodiment includes a resin sheet material 1, a foam layer 20 laminated on the resin sheet material 1, and a skin layer 4 laminated adjacent to the foam layer 20. The base resin of the skin layer 4 and the foam layer 20 contains a thermoplastic resin.

[0018] The foam layer 20 has an internal space 21 formed between the resin sheet material 1 and the skin layer 4, and a plurality of column portions 22 extending from the skin layer 4 to the resin sheet material 1 along the thickness direction. The area ratio of the column portions 22 in a cross section perpendicular to the thickness direction of the foam layer 20 is 10% or more and 60% or less.

[0019] The laminated sheet material 100 can be manufactured, for example, by the following manufacturing method. That is, the laminated sheet material 100 can be manufactured by a manufacturing method including a melting step of melting a base resin containing a thermoplastic resin, an impregnation step of impregnating the base resin with a supercritical fluid of carbon dioxide or nitrogen to make a foamable base resin, and a molding step of injecting the foamable base resin into a mold 7 in which the resin sheet material 1 has been set in advance, and molding by a core-back molding method. Note that Fig. 2 shows an example of an injection molding device 200 that realizes the manufacturing method according to this embodiment.

[0020] The laminated sheet material 100 and a method for producing the same will now be described in detail.

[0021] The laminated sheet material 100 is used, for example, as a surface material for applications that reproduce a specific texture, such as exterior materials for various industrial products, automobile interior materials (exterior materials for the interior of an automobile), sound absorbing materials, heat insulating materials, cushions, and even artificial skin (exterior materials used in parts where it is desired to reproduce the texture of human skin).

[0022] In the following, a case where the laminated sheet material 100 is used as an exterior material for an article will be described as an example. In the following, the surface side (outer surface side) of the laminated sheet material 100 as an exterior material may be simply referred to as the surface side or surface.

[0023] Fig. 1 shows a conceptual diagram illustrating the cross-sectional structure of a laminated sheet material 100. As shown in Fig. 1, the laminated sheet material 100 includes a resin sheet material 1 and a base layer 2 on which a foam layer 20 and a skin layer 4 are laminated. In the laminated sheet material 100, the resin sheet material 1, the foam layer 20, and the skin layer 4 are laminated in this order.

[0024] The resin sheet material 1 is a layer exposed on the surface side of the laminated sheet material 100. The resin sheet material 1 is appropriately selected according to the design and feel required for the surface of the laminated sheet material 100. In this embodiment, the resin sheet material 1 is made of resin (for example, polyurethane), and is a synthetic leather with many air bubbles formed inside the sheet, a polyvinyl chloride sheet (so-called PVC leather), or the like. Examples of such resin sheet materials include "PARMIA (registered trademark)", "REFLA (registered trademark)", "ZUTTFIT (registered trademark)", and "P-TOUCH (registered trademark)" manufactured by Toyo Cross Co., Ltd., "LOOMISH (registered trademark)", "CHRONOS (registered trademark)", "CARAVELL (registered trademark)" (synthetic leather), "Le Carl" manufactured by Kyowa Leather Co., Ltd., and "Bezant (registered trademark)" manufactured by Komatsu Matere Co., Ltd.

[0025] The thickness direction of the laminated sheet material 100 (hereinafter, may be simply referred to as the thickness direction) is the same as the thickness direction of the resin sheet material 1.

[0026] The base layer 2 is a layer of thermoplastic resin carrying the resin sheet material 1 on its surface side. The base layer 2 is a layer that serves as a base or substrate for the resin sheet material 1. The base layer 2 has a foam layer 20 disposed on the resin sheet material 1 side, and a skin layer 4 laminated on the foam layer 20 on the side opposite to the resin sheet material 1 side.

[0027] Examples of the thermoplastic resin forming the base layer 2 (hereinafter referred to as base resin) include polyvinyl chloride resins such as vinyl chloride; polyamide (nylon) resins such as nylon 6, nylon 66, nylon 11, and nylon 12; polyurethane resins; polyolefin resins such as polyethylenes such as low-density polyethylene and linear low-density polyethylene, polypropylene, and ethylene-vinyl acetate copolymers; fluororesins such as FEP, PFA, ETFE, and PTFE; polystyrene resins such as polystyrene, high-impact polystyrene, acrylonitrile-styrene copolymers, and ABS resins; cellulose resins such as cellulose acetate; and thermoplastic elastomers such as polyurethane thermoplastic elastomers, polyester thermoplastic elastomers, styrene thermoplastic elastomers, olefin thermoplastic elastomers, polyamide thermoplastic elastomers, 1,2-polybutadiene thermoplastic elastomers, ethylene-vinyl acetate copolymer thermoplastic elastomers, natural rubber thermoplastic elastomers, fluororubber thermoplastic elastomers, trans-polyisoprene thermoplastic elastomers, and chlorinated polyethylene thermoplastic elastomers. The base layer 2 contains at least one of these as the base resin in a total amount of 75% by weight or more and 100% by mass or less. Among the above base resins, polyolefin resins and thermoplastic elastomers are preferred from the viewpoint of superior flexibility in the thickness direction, and olefin thermoplastic elastomers are more preferred. Specific examples of olefin thermoplastic elastomers include ethylene polymers, propylene copolymers, and butene copolymers. More specific examples include copolymers of ethylene and α-olefins having 3 to 20 carbon atoms, copolymers of ethylene and α-olefins having 3 to 20 carbon atoms and cyclic olefins, ethylene copolymers having various vinyl compounds as comonomers, such as styrene, vinyl acetate, (meth)acrylic acid, and (meth)acrylic acid esters, copolymers of propylene and α-olefins having 4 to 20 carbon atoms, copolymers of propylene and α-olefins having 4 to 20 carbon atoms and cyclic olefins, and ethylene copolymers having various vinyl compounds as comonomers, such as styrene, vinyl acetate, (meth)acrylic acid, and (meth)acrylic acid esters.

[0028] The base resin preferably has a melt flow rate (hereinafter, referred to as MFR) of 3.0 g / 10 min or more and 8.0 g / 10 min or less, measured using a cylinder with an inner diameter of 9.550 mm and a standard die with a hole diameter of 2.095 mm and a hole length of 8.000 mm at a temperature of 190° C. and a load of 2.16 kg in accordance with ASTM D1238. That is, the extrusion amount per unit time (MFR) measured using the above cylinder and die, with the base resin filled in the cylinder, at a temperature of 190° C., and extruding the base resin from the die at a load of 2.16 kg, is preferably 3.0 g / 10 min or more and 8.0 g / 10 min or less.

[0029] As shown in Fig. 3, the base resin of the base layer 2 may have base resin and filler particles P dispersed therein. Fig. 3 shows a cross section of the base layer 2. When the filler particles P are dispersed in the base resin, the content of the filler particles P in the base resin is, for example, 0.01% by mass or more, preferably 0.1% by mass or more, more preferably 0.5% by mass or more, and 30% by mass or less, preferably 20% by mass or less, and more preferably 10% by mass or less, relative to the total amount of the base resin and the filler particles P.

[0030] It is preferable that a gap Q is formed at least partially between the base resin and the filler particles P. For example, the maximum value of the distance between the filler particles P and the base resin is 20% or more and 60% or less of the diameter of the filler particles P. The formation of the gap Q may improve the heat insulation, heat storage, vibration damping, sound absorption, and the like of the laminated sheet material 100. If the compatibility between the base resin and the surfaces of the filler particles P is low, the gap Q is more likely to be formed.

[0031] The average particle size on a volume basis of the filler particles P is, for example, 5 μm or more and 500 μm or less. As the average particle size of the filler particles P, a value measured by a laser diffraction type particle size distribution measuring device may be adopted.

[0032] Examples of the filler particles P are resin beads, metal particles, and inorganic oxide particles. Examples of the metal particles are particles of metals such as iron, lead, copper, zinc, aluminum, nickel, and tin, or particles based on the metals. Among these, iron (iron powder) or particles based on iron may be collectively referred to as iron particles hereinafter. Examples of the inorganic oxide particles are particles of titanium oxide, calcium carbonate, and silica. It is preferable that the filler particles P have a small specific heat. If the specific heat of the filler particles P is small, they are easily cooled in a short time, and the gaps Q are easily formed. The specific heat of the filler particles P is more preferably 1 kJ / (kg·K) or less, and even more preferably 0.5 kJ / (kg·K) or less and 0.1 kJ / (kg·K) or more. Iron particles are particularly preferable as the filler particles P because they have a small specific heat, are excellent in the ability to form the gaps Q, and can form a foamed layer in a short time. The specific heat of iron is 0.435 kJ / (kg·K).

[0033] The filler particles P may be so-called coated particles coated with a coating material having low compatibility with the base resin. That is, the filler particles P may have a core particle P1 and a coating layer P2 formed of a coating material that covers at least a part of the core particle P1, preferably the entire surface of the core particle P1, as shown in Fig. 4. Note that Fig. 4 shows a cross section of the filler particle P.

[0034] An example of a filler particle P as a coated particle is an iron particle such as ferrite that serves as a core particle P1 and is coated with a coating material that has low compatibility with the base resin (e.g., silicone-based resin, fluorine-based resin) to form a coating layer P2.

[0035] As shown in Fig. 1, the skin layer 4 is a layer of dense thermoplastic resin containing almost no air bubbles. "Containing almost no air bubbles" refers to a state in which no air bubbles are contained or only a very small amount of air bubbles are contained. "Containing a very small amount of air bubbles" refers to a state in which, when the cross section is observed with an optical microscope (magnification 20 times), the cross-sectional area of ​​the air bubble portion is 10% or less, preferably 5% or less, more preferably 1% or less, and even more preferably substantially 0% (not detectable). While the resin sheet material 1 is the front surface of the laminated sheet material 100, the skin layer 4 is the back surface of the laminated sheet material 100.

[0036] The foam layer 20 is a layer disposed between the resin sheet material 1 and the skin layer 4. The resin sheet material 1 is laminated adjacent to one surface of the foam layer 20. The resin sheet material 1 is laminated adjacent to the surface of the foam layer 20 opposite to the surface facing the resin sheet material 1. The foam layer 20 preferably has a thickness of 1 mm or more, preferably 2 mm or more, and 20 mm or less, preferably 10 mm or less.

[0037] The foam layer 20 may be a layer formed by laminating a first foam layer 31 arranged on the resin sheet material 1 side, a second foam layer 32 arranged on the skin layer 4 side, and an intermediate foam layer 30 arranged between the first foam layer 31 and the second foam layer 32. In other words, the foam layer 20 may be a layer formed by laminating the first foam layer 31, the intermediate foam layer 30, and the second foam layer 32 in this order from the resin sheet material 1 side to the skin layer 4.

[0038] The foam layer 20 has a plurality of column portions 22 extending from the skin layer 4 to the resin sheet material 1 in the thickness direction. The column portions 22 extend in the thickness direction and are an internal structure of the foam layer 20. The column portions 22 traverse the intermediate foam layer 30 in the thickness direction, and end portions 22a, 22b are formed integrally with the first foam layer 31 and the second foam layer 32, respectively.

[0039] The intermediate foam layer 30 is a layer including an internal space 21 formed between the resin sheet material 1 and the skin layer 4. The internal space 21 is a space formed between adjacent column portions 22. The thickness of the intermediate foam layer 30 in the thickness direction, i.e., the height of the column portions 22 in the thickness direction, is preferably approximately 70% or more and 95% or less of the thickness of the foam layer 20.

[0040] The first foamed layer 31 and the second foamed layer 32 are sponge-like layers containing minute bubbles. As described above, the first foamed layer 31 and the second foamed layer 32 are formed integrally with the ends 22a and 22b of the column portion 22, respectively. It is preferable that the bubbles in the first foamed layer 31 and the second foamed layer 32 are 500 μm or less in terms of number.

[0041] The cross-sectional area ratio of the column portion 22 in a cross section perpendicular to the thickness direction of the foam layer 20 is 10% or more and 60% or less. The cross section perpendicular to the thickness direction of the foam layer 20 is a cross section at a middle position of the foam layer 20 in the thickness direction. When the foam layer 20 includes an intermediate foam layer 30, it corresponds to a cross section at a middle position of the intermediate foam layer 30 in the thickness direction.

[0042] Furthermore, between the resin sheet material 1 and the foam layer 20, there is either no dense thermoplastic resin layer containing almost no air bubbles, such as the skin layer 4, or it is so underdeveloped that it is difficult to clearly distinguish it from the first foam layer 31.

[0043] As described above, the laminated sheet material 100 can be manufactured by a manufacturing method including the melting step, the impregnation step, and the molding step. The laminated sheet material 100 is manufactured by, for example, an injection molding apparatus 200 shown in FIG.

[0044] The injection molding device 200 shown in Fig. 2 includes an extruder 5 which performs a melting process of melting a base resin containing a thermoplastic resin and an impregnation process of impregnating the base resin with a supercritical fluid of carbon dioxide or nitrogen to form a foamable base resin, and a die 7 in which a resin sheet material 1 (see Fig. 1) is set in advance and which performs a molding process in which the foamable base resin is injected to form a laminated sheet material 100. The die 7 is connected to the downstream tip of the extruder 5.

[0045] The extruder 5 has a heat source (e.g., an electric heater) for melting the base resin containing a thermoplastic resin, and includes a cylinder 51 (barrel) that forms a processing space in which the base resin is impregnated with a supercritical fluid of carbon dioxide or nitrogen to form a foamable base resin, a screw 52 that is inserted into the cylinder 51 and extrudes the resin toward the mold 7, a discharge port 53 that is provided at the downstream end of the cylinder 51 and supplies the foamable base resin to the mold 7, a supply port 54 that is provided upstream of the cylinder 51 and supplies the base resin to the processing space in the cylinder 51, a vent port 55 that is provided between the discharge port 53 and the supply port 54 in the cylinder 51, a hopper 61 that supplies the base resin to the supply port 54, and a supercritical gas supply device (a gas cylinder 62 and a pressure regulating valve 63) that supplies the supercritical fluid from the vent port 55 into the cylinder 51. Hereinafter, the processing space in the cylinder 51 will be simply referred to as inside the cylinder 51.

[0046] In the extruder 5, raw materials (base resin and additives such as filler particles) fed into a hopper 61 are fed into the cylinder 51 through a feed port 54. The base resin fed into the cylinder 51 is extruded toward the die 7 by the screw 52 while being melted by heat supplied from the heat source of the cylinder 51. In the process of being extruded toward the die 7, the base resin comes into contact with a supercritical fluid supplied from a vent port 55 and is impregnated with the supercritical fluid to become a foamable base resin (if the raw materials contain additives such as filler particles, it is called a foamable base resin kneaded product. Hereinafter, the foamable base resin kneaded product will be collectively referred to as a foamable base resin). This foamable base resin is fed (injected) into the die 7 in a molten state.

[0047] 5, the mold 7 has a first mold 71 and a second mold 72 which form a molding space S (cavity) for molding the laminated sheet material 100. In the example shown in Fig. 5, a gate 79 is formed in the first mold 71 for supplying the foamable base resin supplied from the discharge port 53 to the molding space S. Note that Fig. 5 shows a cross section of the mold 7.

[0048] The molding space S is formed in a state where the first mold 71 and the second mold 72 are fitted together. As shown in the cross-sectional view of FIG. 6, the molding space S is expanded in volume by moving the second mold 72 relatively away from the first mold 71.

[0049] The laminated sheet material 100 is formed as follows.

[0050] In the mold 7, as shown in the cross-sectional view of Fig. 7, the resin sheet material 1 is set in advance in the second mold 72. The resin sheet material 1 is set so that the front surface side is in contact with the inner surface of the second mold 72. The resin sheet material 1 is set so that it is perpendicular to the direction in which the second mold 72 moves relatively away from the first mold 71.

[0051] As shown in the cross-sectional view of Figure 8, with the resin sheet material 1 set in the mold 7, a molten foamable base resin 2A (including cases where it contains additives such as filler particles) is supplied (injected) from an extruder 5 into the molding space S (see Figure 5), and a laminated sheet material 100 (see Figure 1) is core-back molded.

[0052] After a predetermined period of time has elapsed since the molding space S was filled with the molten material 2A of the foamable base resin, the second mold 72 is slowly separated relatively from the first mold 71 (so-called core back) as shown in the cross-sectional view of FIG. 9. The speed at which the second mold 72 is separated relatively from the first mold 71 is, for example, 0.2 mm / s to 0.6 mm / s. As the second mold 72 is slowly separated relatively from the first mold 71, a foam structure that becomes the foam layer 20 is formed in the molten material 2A. This foam structure is generated by foaming the supercritical fluid gas impregnated in the molten material 2A due to the reduced pressure in the molding space S during the process in which the second mold 72 is separated relatively from the first mold 71.

[0053] When the melt 2A cools and solidifies, it becomes the base layer 2. The foamed structure described above forms a foamed layer 20.

[0054] In addition, the melt 2A of the foamable base resin supplied into the molding space S is cooled by the first mold 71 and solidified early in the vicinity of the inner surface of the first mold 71. Therefore, a foamed structure is not formed in the melt 2A in the vicinity of the inner surface of the first mold 71. The portion of the melt 2A in the vicinity of the inner surface of the first mold 71 where no foamed structure is formed becomes the skin layer 4.

[0055] On the other hand, the melt 2A of the foamable base resin supplied into the molding space S is kept warm by the resin sheet material 1 in the vicinity of the resin sheet material 1 and is prevented from being cooled by the second mold 72, so that the melt 2A does not cool and solidify early. Therefore, a foamed structure is formed in the melt 2A in the vicinity of the resin sheet material 1. Therefore, a dense thermoplastic resin layer containing almost no air bubbles, such as the skin layer 4, is not formed between the resin sheet material 1 and the foam layer 20.

[0056] In the melting step, as described above, the base resin mixture in which the filler particles have been mixed or kneaded in advance may be melted. The filler particles may be mixed and dispersed in the base resin as a so-called master batch, in which the filler particles have been mixed in the base resin at a high concentration in advance. In the melting step, the base resin and the master batch may be melted in a mixed state. In the mixed state of the base resin and the master batch, the content of the filler particles may be 0.5% by mass or more and 30% by mass or less.

[0057] Fig. 10 shows an example of an image of a cross section perpendicular to the surface (resin sheet material 1) of the laminated sheet material 100 produced by the above-mentioned production method. The image shown in Fig. 10 was obtained by observing this cross section with an optical microscope. The structure of the cross section is similar to the structure explained in the conceptual diagram shown in Fig. 1.

[0058] FIG. 11 shows a cross-sectional image of the laminated sheet material 100 shown in FIG. 10 taken along the line XI-XI (a cross-sectional view perpendicular to the thickness direction of the foamed layer 20, and an image of a cross-section of the central part of the foamed layer 20 in the thickness direction). The image shown in FIG. 11 is an optical microscope observation of a cross-section corresponding to the cross-sectional view of the laminated sheet material 100 shown in FIG. 10 taken along the line XI-XI. In FIG. 11, the white areas are the pillars 22, and the rest are the internal space 21 (the end 22b or the second foamed layer 32). In FIG. 12, the pillars 22 in FIG. 11 are highlighted by mapping using image processing. In FIG. 12, the black and white shading in FIG. 11 is shown by filling in areas with a density of 50% or less with black.

[0059] It is preferable that the area of ​​the black-filled region in Figure 12 (the region with a density of 50% or less in terms of the black and white shading in Figure 11), i.e., the area ratio of the cross-section of the column portion 22 in a cross-section perpendicular to the thickness direction of the foam layer 20, is 10% or more and 60% or less.

[0060] In the laminated sheet material 100 as described above, as shown in Fig. 1 and Fig. 10, no skin layer is formed between the resin sheet material 1 and the foam layer 20. Therefore, the tactile sensation from the resin sheet material 1 side of the laminated sheet material 100 does not give the feeling of a hard skin layer, but gives the feeling of natural softness. In other words, the laminated sheet material 100 has high flexibility in the thickness direction.

[0061] Moreover, the above-described manufacturing method of the laminated sheet material 100 does not require a step of removing a skin layer from the base layer 2 in order to make the laminated sheet material 100 highly flexible in the thickness direction. Therefore, the laminated sheet material 100 and its manufacturing method have high productivity.

[0062] In addition, in the laminated sheet material 100 as described above, since no skin layer is formed between the resin sheet material 1 and the foamed layer 20, the internal space 21 is likely to form a structure in which it communicates with the bubbles in the first foamed layer 31 and the resin sheet material 1 via pores, etc. As a result, when the laminated sheet material 100 is compressed, the air G in the internal space 21 is likely to flow out from the internal space 21 to the outside via the first foamed layer 31 and the resin sheet material 1 (see FIG. 1). As a result, the laminated sheet material 100 gives a tactile sensation due to the elastic force of the air spring of the internal space 21 immediately after touching the laminated sheet material 100, and a subsequent sinking tactile sensation when the air G escapes from the internal space 21.

[0063] In addition, in the laminated sheet material 100 as described above, as shown in Figures 1 and 10, a foamed layer 20 including an internal space 21 and column portions 22 is formed, so that in the laminated sheet material 100, the following sensations are felt: a slightly hard sensation due to resistance to the compressive force on the column portions 22 immediately after touching the laminated sheet material 100, followed by a melting-like sensation at the moment when the column portions 22 are bent in a direction intersecting the thickness direction (from the state of the column portions 22 shown in Figure 13 to the state of the column portions 22 shown in Figure 14), and a soft, elastic sensation as the column portions 22 are bent in a direction intersecting the thickness direction.

[0064] The above-mentioned tactile sensation provided by the laminated sheet material 100 can be adjusted by the thickness of the laminated sheet material 100, the foam layer 20, the intermediate foam layer 30 and other layers, and the balance between the column portion 22 and the internal space 21 (for example, the area ratio of the cross-section of the column portion 22).

[0065] In addition, in the laminated sheet material 100, the thermal sensation (the sensation of warmth or coldness and the change in that sensation over time) when touching the laminated sheet material 100 can be adjusted by adjusting the insulating properties generated by the internal space 21 and the heat capacity of the filler particles P (see Figure 3) contained in the base resin.

[0066] Furthermore, in the laminated sheet material 100, by adjusting the size of the gaps Q (see FIG. 3), it is also possible to adjust the timing at which the user feels a change in warmth caused by the heat capacity of the filler particles P. Specifically, for example, when the filler particles P are made of iron or other particles with a large heat capacity, increasing the gaps Q can delay the timing at which the user feels a warmth caused by heat entering or leaving the laminated sheet material 100.

[0067] As described above, the laminated sheet material 100 is excellent in adjusting the touch and warmth. Therefore, the laminated sheet material 100 is also suitable for applications such as expressing a comfortable touch and reproducing the touch of human skin (for example, as a material for artificial skin). In particular, when the laminated sheet material 100 is used as a material for artificial skin, when a magnetic material such as ferrite is used as the filler particles P, the laminated sheet material 100 can be heated by, for example, electromagnetic induction heating to give the sensation of body heat. In addition, even if the laminated sheet material 100 is not heated, the laminated sheet material 100 can also give a warm sensation similar to the warmth of human skin by the heat insulating property of the internal space 21 and the heat storage property of the filler particles P (see FIG. 3). EXAMPLES

[0068] The laminated sheet material according to the present embodiment will be described below based on examples. The laminated sheet described below was manufactured using an apparatus configuration similar to the above-mentioned injection molding apparatus.

[0069] (Examples 1 and 2) The laminated sheet materials according to Examples 1 and 2 were produced as follows.

[0070] The base resin used was an olefin-based thermoplastic elastomer manufactured by Dow Chemical (an example of an ethylene-α-olefin-based copolymer, product name: Engage8200). The filler particles used were soft ferrite manufactured by Powder Tech Co., Ltd. (product name: EF96, average particle size: 35 μm). The MFR of "Engage8200" was 5.0 g / 10 min (190°C, load: 2.16 kg) and the density was 0.870 g / cm 3 It is.

[0071] First, 80 parts by mass of "Engage8200" and 20 parts by mass of "EF96" were mixed and melt-kneaded at 150°C to 200°C in a kneading device (manufactured by Technovel Corporation, model: KZW25) to produce a master batch (hereinafter sometimes referred to as "MB").

[0072] Next, the synthetic leather shown in Table 1 was set as a resin sheet material in a mold having a cavity for forming a laminated sheet material so as to be in contact with the surface of the mold. In this example, the mold was a channel type (one gate).

[0073] The "Engage8200" and the master batch were then pellet-blended in the composition ratio shown in Table 1 to produce a pellet mixture, and this pellet mixture was fed as the raw material into the cylinder of an injection molding machine (an example of an extruder, manufactured by Japan Steel Works, Ltd., J110AD). In the injection molding machine, the cylinder temperature was set to 200°C to melt the raw material (pellet mixture) to produce a molten material. This molten material is a base resin in which 5 parts by mass (5% by mass) of filler particles are mixed and dispersed. The total amount (100% by mass) of the base resin in this molten material is an ethylene-α-olefin copolymer.

[0074] [Table 1]

[0075] In Table 1, "Synthetic Leather 1" is "Permea (for miscellaneous goods)" manufactured by Toyo Cross Co., Ltd.

[0076] In the injection molding machine, a supercritical gas supplying device (TREXEL, model: T-100J) was used to supply the filler gas shown in Table 1 in a supercritical state to the melt and impregnate the base resin to obtain a foamable base resin mixture. In Example 1, carbon dioxide (CO2) was used as the filler gas, and in Example 2, carbon dioxide (N2) was used as the filler gas.

[0077] The amount of the gas (supercritical gas) impregnated into the base resin was 2% by mass relative to the base resin. Then, this foamable base resin mixture was injected into a mold. The initial temperature of the mold (the temperature before the foamable base resin mixture was injected) was 20°C. The back pressure when the foamable base resin mixture was injected into the mold was 10 MPa, and the holding pressure was also 10 MPa. The injection holding pressure time was 0.3 seconds.

[0078] Immediately after 100 seconds of cooling time after injection, supercritical foam molding was performed by the core-back method to obtain a laminated sheet material as a resin foam molded body having a length of 400 mm and a width of 200 mm. The thickness (wall thickness) of the laminated sheet material in Examples 1 and 2 was 6.5 mm.

[0079] In this embodiment, the initial thickness of the cavity in the mold was set to 2.5 mm, the opening distance in the core back was 4 mm, and the opening time (the time to open the mold by the opening distance) was 10 seconds.

[0080] Comparative Example 1 The laminated sheet material according to Comparative Example 1 differs from Example 1 in that no master batch was used as a raw material and no filler particles were contained in the expandable base resin kneaded product, but was otherwise produced in the same manner as Example 1. The thickness (wall thickness) of the laminated sheet material according to Comparative Example 1 was 7.5 mm.

[0081] The laminated sheet materials of the Examples and Comparative Examples were evaluated as follows.

[0082] First, a cross section perpendicular to the surface (resin sheet material 1) of each laminated sheet material was observed. In the laminated sheet material according to the embodiment, a foamed layer was observed having a plurality of pillars extending from the skin layer to the resin sheet, and an internal space formed between these pillars, which is an internal space formed between the resin sheet and the skin layer. In contrast, in the laminated sheet material of the comparative example, it was not possible to grasp the pillars extending from the skin layer to the resin sheet in the region from the skin layer to the resin sheet. In the laminated sheet material of the comparative example, a honeycomb structure was formed in the region from the skin layer to the resin sheet, in which fine independent bubbles (approximately 500 μm in diameter or less) were formed.

[0083] Next, the laminated sheet material according to the embodiment in which the column portion was observed was observed at a cross section perpendicular to the thickness direction of the foamed layer, and the cross section of the central part in the thickness direction of the foamed layer was observed. That is, the foamed layer of each example was cut at the central part in the thickness direction, and the exposed cut surface was photographed at a magnification of 20 times with an optical microscope ("Microscope VHX-7000" manufactured by Keyence Corporation). The image of the cut surface was processed by image processing to divide the brightness (hereinafter referred to as "luminance") of the photographed image into 256 gradations from 0 to 255, and the occurrence frequency of each luminance was calculated, and a luminance value histogram of this image was obtained. Next, the area ratio of the cross section of the column portion (resin) was obtained by binarizing the image using 127 as the luminance threshold value in the automatic area measurement mode. Then, the area ratio of the cross section of the column portion 22 in this cross section was measured, and the area ratio of the cross section of the laminated sheet of Example 1 was 21%. Moreover, the area ratio of the cross section of the laminated sheet of Example 2 was 37%.

[0084] In addition, the hardness of the surface side (resin sheet material side) of each laminate sheet was measured. The hardness was measured using an automatic constant pressure loader (GS-610, manufactured by Techlock Co., Ltd.) and A hardness was measured in accordance with JIS K 6253 (2012). The load during hardness measurement was 500 g, and the load drop rate was 9 mm / s. The hardness of the laminate sheets of Examples 1 and 2 and Comparative Example 1 was 27.8, 27.7, and 46.3, respectively. The laminate sheets of Examples 1 and 2 were more flexible in the thickness direction than the laminate sheet of Comparative Example 1, and were able to achieve a softer feel. The laminate sheets of Examples 1 and 2 did not give the feeling of a hard skin layer, but gave a natural softness. The feel of the laminated sheets of Examples 1 and 2, in more detail, was a slightly hard feel immediately after touching the laminated sheet material from the resin sheet material side, followed by a slightly hard feel that crumbled as if it was melting, and then a soft, elastic feel.

[0085] In this manner, a laminated sheet material having high flexibility in the thickness direction and high productivity, and a method for manufacturing the same can be provided.

[0086] In addition, the configurations disclosed in the above embodiments (including other embodiments, the same applies below) can be applied in combination with configurations disclosed in other embodiments, so long as no contradiction arises. Furthermore, the embodiments disclosed in this specification are examples, and the embodiments of the present disclosure are not limited thereto, and can be appropriately modified within the scope that does not deviate from the purpose of the present disclosure. [Industrial Applicability]

[0087] The present disclosure is applicable to laminated sheet materials and methods for manufacturing the same. [Explanation of symbols]

[0088] 1: Resin sheet material 100: Laminated sheet material 2: Base material layer 20: Foam layer 200: Injection molding equipment 21: Interior space 22: Pillar part 22a: End 22b: End 2A: Melt 30: Middle foam layer 31: First foam layer 32: Second foam layer 4: Skin layer 5: Extrusion machine 51: Cylinder 52: Screw 53:Discharge port 54: Supply port 55: Vent 61: Hopper 62: Gas Cylinder 63: Pressure regulating valve 7: Mold 71: First Mold 72: Second mold 79: Gate G: Air P: Filler particles P1: Nuclear particle P2: Covering layer Q: Gap S: Molding space

Claims

1. A resin sheet material; A foam layer laminated on the resin sheet material; a skin layer laminated adjacent to the foam layer, The base resin of the skin layer and the foam layer contains a thermoplastic resin, The foam layer is An internal space formed between the resin sheet and the skin layer; A plurality of column portions extending from the skin layer to the resin sheet along a thickness direction, In a cross section perpendicular to the thickness direction of the foam layer, the cross-sectional area ratio of the column portion is 20% or more and 60% or less, The base resin has filler particles dispersed therein, The filler particles are iron or iron-based particles, or resin beads having a specific heat of 0.5 kJ / (kg·K) or less.

2. 2. The laminated sheet material of claim 1, wherein said filler particles are ferrite.

3. The content of the filler particles in the base resin is 0.01% by mass or more and 30% by mass or less, 2. The laminated sheet material according to claim 1, wherein the filler particles have an average particle size on a volume basis of 5 μm or more and 500 μm or less.

4. 2. The laminated sheet material according to claim 1, wherein a gap is formed at least partially between the base resin and the filler particles.

5. The laminated sheet material according to claim 1, wherein the thermoplastic resin contains at least one selected from the group consisting of polyvinyl chloride resins, polyamide resins, polyurethane resins, polyolefin resins, fluorine-based resins, polystyrene resins, cellulose resins and thermoplastic elastomers in an amount of 75% by mass or more and 100% by mass or less in total.

6. The thermoplastic resin has a melt flow rate, which is the amount of extrusion per unit time, of 3.0 g / 10 min or more and 8.0 g / 10 min or less, measured using a cylinder with an inner diameter of 9.550 mm and a die with a hole diameter of 2.095 mm and a hole length of 8.000 mm, with the thermoplastic resin filled in the cylinder, the cylinder temperature set to 190°C, and the thermoplastic resin extruded from the die under a load of 2.16 kg.

7. The laminated sheet material according to claim 1 , wherein the foam layer has a thickness of 1 mm or more and 20 mm or less.

8. The content of the filler particles in the base resin is 0.01% by mass or more and 30% by mass or less, The filler particles have an average particle size of 5 μm or more and 100 μm or less on a volume basis, a gap is formed between the base resin and the filler particles, The thermoplastic resin is The composition contains at least one of the group consisting of polyvinyl chloride resins, polyamide resins, polyurethane resins, polyolefin resins, fluorine-based resins, polystyrene resins, cellulose resins, and thermoplastic elastomers in an amount of 75% by mass or more and 100% by mass or less in total, 2. The laminated sheet material according to claim 1, wherein the melt flow rate, which is the amount of extrusion per unit time, is 3.0 g / 10 min or more and 8.0 g / 10 min or less, when a cylinder having an inner diameter of 9.550 mm and a die having a hole diameter of 2.095 mm and a hole length of 8.000 mm is used, the cylinder is filled with thermoplastic resin, the temperature of the cylinder is set to 190°C, and the thermoplastic resin is extruded from the die under a load of 2.16 kg, and measured.

9. A method for producing the laminated sheet material according to any one of claims 1 to 8, comprising: a melting step of melting the base resin; an impregnation step of impregnating the base resin with a supercritical fluid of carbon dioxide or nitrogen to obtain a foamable base resin; and a molding step of injecting the foamable base resin into a mold in which a resin sheet material has been set in advance, and molding the resin by a core-back molding method.

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