JP5427972B2 - Resin foam - Google Patents

Description

  The present invention relates to a resin foam, a foamed member laminate, and electrical / electronic devices using the resin foam.

  In general, the resin foam is punched in the required shape according to the shape of the member used, and the surface of the resin foam is subjected to adhesive processing to facilitate fixing to the member. However, since the resin foam subjected to such processing is not easy to handle, a carrier tape may be used to efficiently transport the resin foam to a predetermined location. That is, the resin foam is subjected to various types of processing (such as punching or adhesive processing) while being adhered to the carrier tape, or is conveyed after processing. On the other hand, after processing, the resin foam needs to be peeled off from the carrier tape. However, if the strength of the surface of the resin foam is low (weak), the resin foam may be destroyed at the time of peeling. It was. In particular, in the case of a resin foam having a high expansion ratio [for example, heat formed through a process of depressurizing after impregnating a thermoplastic resin with a high-pressure inert gas (for example, supercritical carbon dioxide). Plastic resin foam, etc.], and the thickness of the cell wall was thin, so the breakage at the time of peeling was remarkable.

  It is known that a resin layer is provided on the surface of the resin foam in order to improve the adhesiveness and sealability of the resin foam. For example, for the purpose of improving the sealing performance (reinforcement of the foam layer and conveyance with a carrier tape is not considered), rubber foam is formed on one of the upper and lower surfaces of a rubber foam having both closed cells and open cells. A foam having a soft coating softer than the body has been proposed (see Patent Document 1). Moreover, by forming a layer made of a urethane-based thermoplastic polymer composition on the surface of the polyolefin resin foam, and applying a surface treatment layer made of a polar polymer on the layer, toughness, scratch resistance, A foam having excellent wear resistance has been proposed (see Patent Document 2). Furthermore, the foam (refer patent document 3) by which the foam surface was processed with the polychloroprene-type adhesive composition, and the foam (patent document 4) by which the easily water-soluble layer (polyvinyl alcohol layer etc.) was provided in the foam surface. For example). These are all laminated with different materials on the foam, which may change the physical properties of the foam, and the manufacturing process becomes complicated.

  In addition, if a carrier tape with lower adhesive strength is used to prevent breakage at the time of peeling, there will be minute bubbles due to foaming on the surface of the resin foam, so the contact area cannot be earned and will shift during processing. The problem that dimensional stability (shape stability) fell and the problem that it peeled off from a carrier tape before peeling from the base_sheet | mounting_paper in the case of assembling a foam member had arisen.

JP-A-9-131822 JP 2003-136647 A Japanese Patent Laid-Open No. 5-24143 Japanese Patent Laid-Open No. 10-37328

  Accordingly, an object of the present invention is to suppress or prevent foam breakage when peeling from a carrier tape, even if it is a resin foam having a high foaming ratio, and processability and conveyance while being held on the carrier tape. Another object of the present invention is to provide a resin foam having excellent properties, a foam member laminate using the resin foam, and electrical / electronic devices using the resin foam.

  As a result of intensive studies to solve the above problems, the present inventors have provided a specific surface layer by heat melting treatment in a specific resin foam, and when the surface coverage is adjusted, the carrier tape is peeled off. It has been found that foam breakage can be suppressed or prevented at the time, and further, it is excellent in workability and transportability when held on a carrier tape, and is suitable for use in electrical and electronic equipment. The present invention has been completed based on these findings.

前記発泡体層の密度が０．２０ｇ／ｃｍ³以下であり、
前記樹脂発泡体を構成する樹脂が熱可塑性樹脂であり、
前記表面層が加熱溶融処理により形成されており、
樹脂発泡体の厚みが０．２〜５ｍｍであり、
電気・電子機器類に用いることを特徴とする樹脂発泡体を提供する。 That is, the present invention is a resin foam having a foam layer and a surface layer, the foam layer and the surface layer have the same composition, and the surface coverage of the surface layer (formula (1)) Definition) is 40% or more,

The foam layer has a density of 0.20 g / cm ³ or less;
The resin constituting the resin foam is a thermoplastic resin,
The surface layer is formed by heat melting treatment,
The thickness of the resin foam is 0.2 to 5 mm,
Provided is a resin foam characterized by being used in electrical and electronic equipment.

  Furthermore, the present invention provides the resin foam, wherein the thermoplastic resin is a polyolefin resin.

  Furthermore, the present invention provides the resin foam, wherein the temperature of the heat-melting treatment is equal to or higher than a temperature defined by [(softening point or melting point of resin constituting the resin foam) −15 ° C.].

  Furthermore, this invention provides the said resin foam formed through the process of pressure-reducing, after impregnating resin with a high voltage | pressure gas.

  Furthermore, the present invention provides the resin foam, wherein the gas is an inert gas.

  Furthermore, the present invention provides the resin foam, wherein the inert gas is carbon dioxide.

  Furthermore, the present invention provides the resin foam, wherein the high-pressure gas is in a supercritical state.

  Furthermore, the present invention provides the above resin foam having a closed cell structure or a semi-continuous semi-closed cell structure.

  Furthermore, this invention provides the foaming member in which the said resin foam is used.

  Furthermore, this invention provides the said foaming member which has the said surface layer in the one side of a foam layer, and has an adhesive layer in the other side.

  Furthermore, this invention provides the said foaming member whose adhesive layer is an acrylic adhesive layer.

  Furthermore, the present invention provides the foamed member used for electric / electronic devices.

  Furthermore, the present invention provides a foamed member laminate having a structure in which a resin foam is held by a carrier tape having an adhesive layer on at least one side of a substrate, wherein the resin foam is the resin foam described above. In addition, the configuration in which the resin foam is held by the carrier tape is a configuration in which the surface foam and the adhesive layer of the carrier tape are in contact with each other, and the resin foam is adhered to the carrier tape. A foamed member laminate is provided.

  Furthermore, the present invention provides electronic / electrical equipment using foamed members, wherein the foamed member is the foamed member for electrical / electronic equipment described above.

  According to the resin foam of the present invention, since it has the above-described configuration, it is possible to suppress or prevent foam breakage when peeling from the carrier tape even if it has a high expansion ratio. Excellent properties for carrier tape such as workability and transportability.

FIG. 1 is an FT-IR chart of the first embodiment.

本願では、表面被覆率（式（１）で定義）が４０％以上である表面層を「特定の表面層」と称する場合がある。 (Resin foam)
The resin foam of the present invention has at least a foam layer and a surface layer, the compositions of the foam layer and the surface layer are the same, and the surface coverage of the surface layer (defined by the formula (1)) is 40. % Or more. In addition, the surface coverage defined by the formula (1) may be simply referred to as “surface coverage”.

In the present application, a surface layer having a surface coverage (defined by equation (1)) of 40% or more may be referred to as a “specific surface layer”.

  The surface layer is a layered region having a height of 20 μm from the surface of the resin foam, and unlike the foam layer, the surface layer is a layered portion having a dense structure having a non-uniform cell structure.

  The foam layer is a portion having a structure in which bubbles are uniformly distributed, and is a layered portion occupying almost the entire resin foam.

In the present invention, the apparent density of the foam layer can be appropriately set depending on the purpose of use, but is 0.20 g / cm ³ or less (preferably 0.15 g / cm ³ or less, more preferably 0.13 g). / Cm ³ or less). The lower limit of the apparent density of the resin foam is preferably 0.02 g / cm ³ or more (preferably 0.03 g / cm ³ or more). When the apparent density of the foam layer exceeds 0.20 g / cm ³ , foaming may be insufficient and a problem may be caused in that flexibility is impaired. On the other hand, if it is less than 0.02 g / cm ³ , the strength of the resin foam may be significantly lowered, which is not preferable.

  In the resin foam of the present invention, the composition of the surface layer and the foamed layer is the same. The “same composition” means “same or almost the same”, and “substantially the same” means that the main polymers of the resins constituting the resin foam are the same.

  For example, the fact that the composition of the surface layer and the foam layer is almost the same means that the main absorption is compared in the chart when the FT-IR analysis of the surface of the surface layer and the arbitrary cut surface of the foam layer is performed. Can be determined. When the main absorption is the same, it means that the composition of the surface layer and the foamed layer is almost the same (see FIG. 1). The above “arbitrary cut surface of the foam layer” is a cut surface in a direction perpendicular to the thickness direction.

  The resin foam of the present invention may have a specific surface layer on one side of the foam layer, or may have a specific surface layer on both sides of the foam layer. When the resin foam of the present invention has a specific surface layer on one side of the foam layer, the surface opposite to the specific surface layer is formed by another surface layer (a surface layer that is not a specific surface layer). The surface provided may be a surface provided by a foam layer. In addition, the shape of the resin foam of the present invention is not particularly limited, and examples thereof include a sheet shape, a tape shape, and a film shape.

  On the surface of the specific surface layer of the resin foam of the present invention, the area of the pores existing on the surface of the foam (the area of the holes occupied on the surface of the foam) is small, and the adhesion area with the carrier tape can be increased. Moreover, since the resin foam of this invention has a surface layer, it has high surface strength with the characteristic (for example, extensibility, a softness | flexibility etc.) of a resin foam. For this reason, the resin foam of the present invention may use a carrier tape during processing or conveyance, but exhibits good characteristics with respect to the carrier tape. Specifically, when a specific surface layer side of a resin foam is affixed to a carrier tape, and the resin foam is peeled off from the carrier tape after being processed or transported while being held on the carrier tape The foam can be easily peeled off at the interface between the resin foam and the carrier tape, and the foam does not break in the foam layer. In addition, the specific surface layer of the resin foam exhibits sufficient adhesive strength that the carrier tape does not peel off during processing or transport, so when processing or transporting the resin foam while being held on the carrier tape The behavior of holding the resin foam of the carrier tape is stable, and processing defects and conveyance failures of the resin foam do not occur. In addition, as a carrier tape, the carrier tape generally used can be widely used, for example, the below-mentioned carrier tape is mentioned.

  In the specific surface layer of the resin foam of the present invention, the larger the surface coverage value, the larger the adhesion area when the carrier tape is bonded to the specific surface layer side of the resin foam. Since a high peeling force can be exhibited with respect to the tape, the surface coverage is 40% or more, preferably 43% or more, and more preferably 45% or more. In the present invention, when the surface coverage is less than 40%, the peel strength with respect to the carrier tape is reduced, and the resin foam of the carrier tape is held when the resin foam is processed or conveyed while being held on the carrier tape. The behavior may become unstable. If the surface coverage is 100%, there will be no pores on the foam surface.

  Moreover, in the specific surface layer of the resin foam of the present invention, the surface coverage is preferably 97% or less, more preferably 95% or less, from the viewpoint of maintaining high flexibility when compressed and used. More preferably, it is 90% or less.

L ^* (brightness) on the surface of the specific surface layer of the resin foam of the present invention is preferably 33.0 or less, preferably 32. 0 or less, more preferably 31.0 or less.

L ^* (brightness) is one of the attributes of a color, and is the degree of lightness and darkness of the color. The higher the brightness value, the brighter the color. If L ^* (brightness) is 100, the color is white, and if 0, the color is black. In addition, when there are many fine holes on the surface of the resin foam, irregular reflection occurs on the surface, and the brightness tends to increase.

  As described above, the resin foam of the present invention may be processed and transported in a state where the specific surface layer side is affixed to the carrier tape and held on the carrier tape. The behavior of the carrier tape holding the resin foam during proper transport and processing is related to the peeling phenomenon at a low speed, and sufficient adhesive strength [for example, 23 ° C., 50 RH] that does not peel during processing and transport. %, Tensile speed: 0.3 m / min, Peeling angle: Adhesive strength when measured by peeling under conditions of 180 ° (low speed peeling conditions) is 0.30 N / 20 mm or more (preferably 0.35 N / 20 mm or more) Etc.].

  In addition, the resin foam of the present invention is peeled off from the carrier tape after the specific surface layer side is affixed to the carrier tape and the resin foam is processed and transported while being held on the carrier tape. The behavior when the foam is peeled off from the carrier tape is related to the peeling phenomenon at high speed, and in this high speed peeling (high speed peeling; for example, when the tensile speed is 10 m / min), the carrier It must be peeled in the state of interfacial peeling that peels at the interface between the tape and the specific surface layer of the resin foam. Furthermore, when the resin foam is peeled from the carrier tape, it is necessary to suppress or prevent the foam breakage. Therefore, it is measured by peeling with a high-speed peeling force [high-speed peeling conditions (for example, conditions of 23 ° C., 50 RH%, tensile speed: 10 m / min, peeling angle: 180 °) to the carrier tape of a specific surface layer of the resin foam. Is preferably 0.25 N / 20 mm or less (preferably 0.20 N / 20 mm or less).

  Furthermore, since the resin foam has a specific surface layer, it can exhibit excellent reworkability. Specifically, the resin foam of the present invention is, for example, a resin foam even after the resin foam is affixed to an adherend in a state compressed to 50% and aged at 50 ° C. for 7 days. Can be easily peeled off from the adherend without damage. Reworkability refers to the resin surface and metal surface of the device housing, the glass surface of the image display unit, etc. when the resin foam (foamed member) is incorporated in an electric / electronic device or the like as a dustproof material or sealing material. It refers to the property that it can be easily peeled off without sticking to. If the resin foam (foamed member) sticks to the surface of the adherend as described above, the foamed member will be damaged when disassembling the equipment for maintenance, etc., and as a dustproof material or sealing material, etc. There is a risk that the function of will not be performed. Moreover, if the resin foam (foamed member) cannot be easily peeled off from the adherend, it is difficult to separate and collect each material at the time of disassembly, which may hinder the reuse of the material. Therefore, it is preferable that the resin foam has excellent reworkability.

  As described above, the resin foam of the present invention has a foam layer and a specific surface layer as essential components. The resin foam of the present invention is not particularly limited. For example, after a foamed structure is obtained by foaming and molding a resin composition containing a resin that is a material of the resin foam, a specific surface of the foamed structure is obtained. It is preferable to produce by forming a layer. In this preferred method, the foam layer is formed when a specific surface layer is formed on the foam structure.

  In the present invention, the thermoplastic resin (thermoplastic polymer) that is the material of the resin foam is not particularly limited as long as it is a polymer exhibiting thermoplasticity and can be impregnated with a high-pressure gas. Examples of such thermoplastic resins include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, copolymers of ethylene and propylene, ethylene or propylene and other α-olefins (for example, , Butene-1, pentene-1, hexene-1, 4-methylpentene-1, etc.), ethylene and other ethylenically unsaturated monomers (for example, vinyl acetate, acrylic acid, acrylic ester) , Methacrylic acid, methacrylic acid ester, vinyl alcohol, etc.) and other polyolefin resins; polystyrene, acrylonitrile-butadiene-styrene copolymer (ABS resin) and other styrene resins; 6-nylon, 66-nylon Polyamide resins such as 12-nylon; Polyimide; Polyetherimide; Acrylic resin such as polymethyl methacrylate; Polyvinyl chloride; Polyvinyl fluoride; Alkenyl aromatic resin; Polyester resin such as polyethylene terephthalate and polybutylene terephthalate; Bisphenol A polycarbonate Polycarbonate; polyacetal; polyphenylene sulfide and the like. A thermoplastic resin can be used individually or in combination of 2 or more types. In addition, when a thermoplastic resin is a copolymer, the copolymer of any form of a random copolymer and a block copolymer may be sufficient.

  As the thermoplastic resin, a polyolefin resin can be suitably used. As the polyolefin-based resin, it is preferable to use a resin having a broad molecular weight distribution and having a shoulder on the high molecular weight side, a slightly cross-linked resin (a slightly cross-linked resin), a long-chain branched resin, or the like.

  In the present invention, it is preferable to use a rubber component and / or a thermoplastic elastomer component together with the thermoplastic resin. The ratio of the rubber component and / or the thermoplastic elastomer component is not particularly limited. The mixing ratio (% by weight) of the mixture of the polyolefin resin as the thermoplastic resin and the rubber component and / or the thermoplastic elastomer component is, for example, the former / the latter = 1/99 to 99/1 (preferably 10/90). To 90/10, more preferably 20/80 to 80/20). In a mixture of a thermoplastic resin and a rubber component and / or a thermoplastic elastomer component, if the ratio of the rubber component and / or the thermoplastic elastomer component is less than 1% by weight, the cushioning property of the resin foam tends to be lowered. On the other hand, if it exceeds 99% by weight, outgassing easily occurs during foaming, and it becomes difficult to obtain a highly foamable foam.

  The rubber component or thermoplastic elastomer component is not particularly limited as long as it has rubber elasticity and can be foamed. For example, natural rubber, polyisobutylene, polyisoprene, chloroprene rubber, butyl rubber, nitrile butyl rubber and the like are used. Or synthetic rubber; olefin-based elastomers such as ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-vinyl acetate copolymer, polybutene, chlorinated polyethylene; styrene-butadiene-styrene copolymer, styrene- Examples thereof include styrene elastomers such as isoprene-styrene copolymers and hydrogenated products thereof; polyester elastomers; polyamide elastomers; and various thermoplastic elastomers such as polyurethane elastomers. These rubber components or thermoplastic elastomer components can be used alone or in combination of two or more. Since these rubber components and thermoplastic elastomer components have, for example, a glass transition temperature of room temperature or lower (for example, 20 ° C. or lower), the resin foam of the present invention is used as a foamed member (for example, a dustproof material or a seal material). It is extremely excellent in flexibility and shape following ability.

  As the rubber component and / or the thermoplastic elastomer component used together with the thermoplastic resin, an olefin elastomer can be preferably used. The olefin elastomer usually has a structure in which an olefin resin component such as polyethylene or polypropylene and an olefin rubber component such as ethylene-propylene rubber or ethylene-propylene-diene rubber are microphase-separated. A type in which each component is physically dispersed or a type in which a heat treatment is performed dynamically in the presence of a crosslinking agent may be used, and the compatibility with a polyolefin resin used as a thermoplastic resin is good.

  The resin foam of the present invention may further contain powder particles. The powder particles can exhibit a function as a foam nucleating agent during foam molding. Therefore, the resin foam of a favorable foaming state can be obtained by mix | blending powder particle. Examples of powder particles include powdered talc, silica, alumina, zeolite, calcium carbonate, magnesium carbonate, barium sulfate, zinc oxide, titanium oxide, aluminum hydroxide, magnesium hydroxide, mica, montmorillonite, etc., carbon particles Glass fiber, carbon tube, etc. can be used. The powder particles can be used alone or in combination of two or more.

  In the present invention, powder particles having an average particle diameter (particle diameter) of about 0.1 to 20 μm can be suitably used as the powder particles. If the average particle size of the powder particles is less than 0.1 μm, it may not function sufficiently as a nucleating agent, and if the particle size exceeds 20 μm, it may cause gas loss during foam molding.

  Although it does not restrict | limit especially as a compounding quantity of a powder particle, For example, it is 0.1-150 weight part (preferably 1-150 weight part with respect to 100 weight part of total amounts of a thermoplastic resin, a rubber component, and / or a thermoplastic elastomer component. 130 parts by weight, more preferably 2 to 50 parts by weight). When the blending amount of the powder particles is less than 0.1 parts by weight with respect to 100 parts by weight of the thermoplastic resin, it becomes difficult to obtain a uniform foam. On the other hand, when the amount exceeds 150 parts by weight, the resin composition As the viscosity of the foam increases significantly, outgassing occurs during foaming, which may impair foaming characteristics.

  Moreover, since the resin foam is comprised with the thermoplastic resin, it has the characteristic of being easy to burn. Therefore, when the foamed member in which the resin foam of the present invention is used is used for an application indispensable to impart flame retardancy such as electrical / electronic equipment, it has flame retardancy as powder particles. It is preferable that powder particles (for example, various powdery flame retardants) are blended. In addition, a flame retardant can be used with powder particles other than a flame retardant.

  In the present invention, an inorganic flame retardant is suitable as the flame retardant in the powdery flame retardant. As the inorganic flame retardant, for example, a brominated flame retardant, a chlorinated flame retardant, a phosphorus flame retardant, an antimony flame retardant, etc. may be used. It produces gas components that are harmful and corrosive to equipment. Phosphorus flame retardants and antimony flame retardants have problems such as toxicity and explosive properties. A flame retardant can be suitably used. Examples of the non-halogen-nonantimony inorganic flame retardant include hydrated metal compounds such as aluminum hydroxide, magnesium hydroxide, magnesium oxide / nickel oxide hydrate, magnesium oxide / zinc oxide hydrate, and the like. . The hydrated metal oxide may be surface treated. A flame retardant can be used individually or in combination of 2 or more types.

  When the flame retardant is used, the amount of the flame retardant used is not particularly limited. For example, the amount of the flame retardant is 5 to 130 parts by weight with respect to 100 parts by weight of the total amount of the thermoplastic resin and the rubber component and / or the thermoplastic elastomer component ( Preferably, it can be suitably selected from the range of 10 to 120 parts by weight. If the amount of the flame retardant used is too small, the flame retardant effect is reduced. Conversely, if the amount is too large, it is difficult to obtain a highly foamed foam.

  Various additives may be blended in the resin composition as necessary. The kind of additive is not particularly limited, and various additives usually used for foam molding of resins can be used. Specifically, as additives, for example, cell nucleating agent, crystal nucleating agent, plasticizer, lubricant, colorant (pigment, dye, etc.), ultraviolet absorber, antioxidant, anti-aging agent, filler, reinforcing agent , Antistatic agents, surfactants, tension modifiers, shrinkage inhibitors, fluidity modifiers, clays, vulcanizing agents, surface treatment agents, various forms of flame retardants other than powders, and the like. The addition amount of the additive can be appropriately selected within a range that does not impair the formation of bubbles and the like, and the addition amount used at the time of molding a normal thermoplastic resin can be adopted.

  As described above, the resin foam of the present invention is usually produced by foaming and molding a resin composition to obtain a foam structure, and then forming a specific surface layer on the foam structure. . The resin composition can be obtained by mixing a resin constituting the resin foam and an additive or the like added as necessary.

  In the resin foam of the present invention, the foaming method used when foaming and molding the resin composition to obtain a foamed structure is not particularly limited, and is usually used, for example, a physical method or a chemical method. A method is mentioned. A general physical method is a method of forming bubbles by dispersing a low boiling point liquid (foaming agent) such as chlorofluorocarbons or hydrocarbons in a resin, and then heating to volatilize the foaming agent. Moreover, a general chemical method is a method in which bubbles are formed by a gas generated by thermal decomposition of a compound (foaming agent) added to a resin. However, general physical methods are concerned about flammability and toxicity of substances used as foaming agents, and environmental effects such as ozone layer destruction. In addition, in general chemical methods, the residue of foaming gas does not remain in the foam. Therefore, contamination with corrosive gas or impurities in the gas is a problem, especially in electronic equipment applications where low pollution requirements are high. Become. Moreover, in any of these physical methods and chemical methods, it is difficult to form a fine bubble structure, and it is particularly difficult to form a fine bubble of 300 μm or less.

  For this reason, in the present invention, as a foaming method used when foaming and molding a resin composition to obtain a foam structure, a foam having a small cell diameter and a high cell density can be easily obtained. A method using a high-pressure gas as the foaming agent is preferable, and a method using a high-pressure inert gas as the foaming agent is particularly preferable. The inert gas means a gas that is inert with respect to the resin in the resin composition. That is, the cell structure (foamed structure) of the resin foam of the present invention is particularly preferably formed by a method using a high-pressure inert gas as a foaming agent.

  In the resin foam of the present invention, as a method of obtaining a foam structure by foaming and molding by using a resin composition as a foaming agent and using a high-pressure gas, specifically, the resin composition is impregnated with a high-pressure gas. A method of forming through a step of reducing the pressure after the step of impregnating, and a method of forming through a step of reducing the pressure after impregnating an unfoamed molded article made of the resin composition with a high-pressure gas, or a molten resin composition A preferable method includes a method in which a gas (for example, an inert gas) is impregnated under pressure and then subjected to molding together with reduced pressure. That is, the cell structure (foamed structure) of the resin foam of the present invention is preferably formed through a step of depressurizing after impregnating with a high-pressure gas.

  The inert gas is not particularly limited as long as it is inert to the resin and can be impregnated, and examples thereof include carbon dioxide, nitrogen gas, and air. These gases may be mixed and used. Of these, carbon dioxide can be suitably used because the amount of impregnation into the resin used as the material of the foam is large and the impregnation speed is high.

  Furthermore, from the viewpoint of increasing the impregnation rate into the resin composition, the high-pressure gas (particularly inert gas, and further carbon dioxide) is preferably in a supercritical state. In the supercritical state, the solubility of the gas in the resin is increased and high concentration can be mixed. In addition, when the pressure drops suddenly after impregnation, since it is possible to impregnate at a high concentration as described above, the generation of bubble nuclei increases, and the density of bubbles formed by the growth of the bubble nuclei has a porosity. Even if they are the same, they become larger, so that fine bubbles can be obtained. Carbon dioxide has a critical temperature of 31 ° C. and a critical pressure of 7.4 MPa.

  When a foamed structure is produced by impregnating a resin composition with a high-pressure gas, the resin composition is previously molded into an appropriate shape such as a sheet, for example. (Foamed molded product), this unfoamed resin molded body may be impregnated with a high-pressure gas and foamed by releasing the pressure, and the resin composition may be used together with the high-pressure gas under pressure. Kneading and molding may be performed at the same time as releasing the pressure, and a continuous method in which molding and foaming are performed simultaneously. In this way, a pre-molded unfoamed resin molded article may be impregnated with a high-pressure gas, or a molten resin composition is impregnated with a high-pressure gas under pressure and then molded during decompression. You may attach to.

  Specifically, when producing a resin structure by a batch method, as a method of producing an unfoamed resin molded body, for example, a resin, and a rubber component and / or a thermoplastic elastomer component used as necessary, Also, a method of molding a resin composition containing powder particles and other additives used as necessary using an extruder such as a single screw extruder or a twin screw extruder, the same resin composition as described above A kneading machine using blades such as rollers, cams, kneaders, and banbari molds, and then press-molding to a predetermined thickness using a hot plate press, etc., injection molding And a method of molding using a machine. What is necessary is just to shape | mold by the appropriate method from which the molded object of desired shape and thickness is obtained. An unfoamed resin molded body (molded body made of a resin composition) thus obtained is placed in a pressure-resistant container (high-pressure container), and high-pressure gas (especially inert gas, further carbon dioxide) is injected (introduced), Gas impregnation process for impregnating a high-pressure gas into an unfoamed resin molded body, and a pressure reduction process for releasing bubble pressure (usually up to atmospheric pressure) when a sufficiently high-pressure gas is impregnated to generate bubble nuclei in the resin. In some cases (if necessary), bubbles are formed in the resin through a heating step of growing bubble nuclei by heating. Note that bubble nuclei may be grown at room temperature without providing a heating step. After the bubbles are grown in this way, the foamed structure can be obtained by rapidly cooling with cold water or the like as necessary to fix the shape. The shape of the unfoamed resin molded body is not particularly limited, and may be any of a roll shape, a plate shape, and the like. The introduction of high-pressure gas may be performed continuously or discontinuously. Furthermore, as a heating method for growing bubble nuclei, a known or conventional method such as a water bath, an oil bath, a hot roll, a hot air oven, a far infrared ray, a near infrared ray, or a microwave can be employed. Furthermore, the unfoamed resin molded body (unfoamed molded product) to be used for foaming is not limited to a sheet-like product, and various shapes (for example, prismatic shapes) can be used depending on the application. Moreover, the non-foamed resin molding to be subjected to foaming can be produced by other molding methods besides extrusion molding, press molding, and injection molding.

  On the other hand, when producing a foam structure by a continuous method, for example, a resin, a rubber component and / or a thermoplastic elastomer component used as necessary, and powder particles and other additives used as necessary High-pressure gas (especially inert gas and carbon dioxide) is injected (introduced) while kneading the resin composition containing the agent using an extruder such as a single-screw extruder or a twin-screw extruder. The pressure is released (usually up to atmospheric pressure) by extruding the resin composition through a kneading impregnation step for impregnating the resin composition with a sufficiently high pressure gas, a die provided at the tip of the extruder, etc. It can be manufactured by a molding decompression step in which foaming is performed simultaneously. In some cases (if necessary), a heating step of growing bubbles by heating may be provided. After the bubbles are grown in this way, the foamed structure can be obtained by rapidly cooling with cold water or the like as necessary to fix the shape. The kneading impregnation step and the molding pressure reduction step can be performed using an injection molding machine or the like in addition to the extruder. Moreover, what is necessary is just to select suitably the method of obtaining the foam-like structure of a sheet form, prismatic form, and other arbitrary shapes.

  The mixing amount of the gas is not particularly limited, but is, for example, about 2 to 10% by weight with respect to the total amount of the resin components in the resin composition. What is necessary is just to mix suitably adjusting so that a desired density and expansion ratio may be obtained.

  In the gas impregnation step in the batch method or the kneading impregnation step in the continuous method, the pressure when the gas is impregnated into the unfoamed resin molded product or the resin composition can be appropriately selected in consideration of the type of gas and operability, For example, when an inert gas is used as the gas, particularly carbon dioxide, it is 6 MPa or more (for example, about 6 to 100 MPa), preferably 8 MPa or more (for example, about 8 to 100 MPa). When the gas pressure is lower than 6 MPa, the bubble growth during foaming is remarkable, the bubble diameter becomes too large, and disadvantages such as, for example, a reduction in the dustproof effect are likely to occur, which is not preferable. This is because, when the pressure is low, the amount of gas impregnation is relatively small compared to when the pressure is high, and the number of bubble nuclei formed is reduced due to a decrease in the bubble nucleus formation rate. This is because the bubble diameter becomes extremely large. Further, in the pressure region lower than 6 MPa, the bubble diameter and the bubble density change greatly only by slightly changing the impregnation pressure, so that it is difficult to control the bubble diameter and the bubble density.

  The temperature at which high-pressure gas is impregnated into a non-foamed resin molded product or resin composition in the gas impregnation step in a batch method or the kneading impregnation step in a continuous method varies depending on the type of gas or resin used and can be selected over a wide range. However, in consideration of operability and the like, for example, the temperature is about 10 to 350 ° C. For example, in a batch system, the impregnation temperature when impregnating a sheet-like unfoamed resin molded body with a high-pressure gas is about 10 to 200 ° C. (preferably 40 to 200 ° C.). In the continuous method, the temperature at which high-pressure gas is injected into the resin composition and kneaded is generally about 60 to 350 ° C. When carbon dioxide is used as the high-pressure gas, the temperature during impregnation (impregnation temperature) is preferably 32 ° C. or higher (particularly 40 ° C. or higher) in order to maintain a supercritical state.

  In the decompression step, the decompression speed is not particularly limited, but is preferably about 5 to 300 MPa / second in order to obtain uniform fine bubbles. Moreover, the heating temperature in the said heating process is about 40-250 degreeC (preferably 60-250 degreeC), for example.

  Moreover, according to such a manufacturing method of a foam structure, since a foam structure with a high expansion ratio can be manufactured, there is an advantage that a thick resin foam can be manufactured. For example, in the case of producing a foam structure in a continuous manner, in order to maintain the pressure inside the extruder in the kneading impregnation step, the gap between the dies attached to the tip of the extruder is as narrow as possible (usually 0.1 to 1.. 0 mm). Therefore, in order to obtain a thick foam structure, the resin composition extruded through a narrow gap must be foamed at a high magnification. Conventionally, however, a high foaming ratio cannot be obtained. Has been limited to a thin thickness (for example, about 0.5 to 2.0 mm). On the other hand, the foam structure manufactured using high-pressure gas can continuously obtain a foam having a final thickness of 0.50 to 5.00 mm. In order to obtain such a thick foam structure, the relative density of the foam structure (density after foaming / density in an unfoamed state) is 0.02 to 0.30 (preferably 0.05 to 0). .25) is desirable. When the relative density exceeds 0.30, foaming is insufficient, which may cause problems in flexibility, and when it is less than 0.02, the strength of the foamed structure may be remarkably lowered.

In the present invention, the apparent density of the foam layer (foam structure), as described above, 0.20 g / cm ³ or less (preferably 0.15 g / cm ³ or less, more preferably 0.13 g / cm ³ or less ) Is preferable. The lower limit of the apparent density of the resin foam is preferably 0.02 g / cm ³ or more (preferably 0.03 g / cm ³ or more).

  The apparent density of the foam layer can be controlled, for example, by adjusting the expansion ratio according to the amount and pressure of the gas impregnated into the resin composition when the resin foam is produced.

The apparent density of the foam layer is determined as follows. The resin foam is punched with a 40 mm × 40 mm punching blade mold, and the dimensions of the punched sample are measured. Further, the thickness is measured with a 1/100 dial gauge having a measurement terminal diameter (φ) of 20 mm. The volume of the thermoplastic resin foam is calculated from these values. Next, the weight of the foam layer is measured with an upper pan balance having a minimum scale of 0.01 g or more. From these values, the apparent density (g / cm ³ ) of the foam layer is calculated.

  The cell structure of the resin foam is not particularly limited, but there is a closed cell structure, a semi-continuous semi-closed cell structure (a cell structure in which a closed cell structure and an open cell structure are mixed, and the ratio is not particularly limited). In particular, a cell structure in which the closed cell structure part is 40% or less, preferably 30% or less in terms of flexibility in the cell structure of the foam layer of the resin foam is suitable. The cell structure can be controlled, for example, by adjusting the expansion ratio according to the amount of gas impregnated in the resin composition and the pressure when preparing the resin foam described later.

  The thickness, relative density, apparent density, etc. of the foamed structure are determined according to the type of gas used, thermoplastic resin, rubber component and / or thermoplastic elastomer component, for example, a gas impregnation step or a kneading impregnation step. By appropriately selecting and setting operating conditions such as temperature, pressure, time, etc., decompression speed in the decompression process or molding decompression process, operating conditions such as temperature, pressure, etc., heating temperature in the heating process after decompression or after molding decompression, etc. Can be adjusted.

  As described above, the resin foam of the present invention is preferably produced by foaming and molding the resin composition to obtain a foam structure, and then forming a specific surface layer on the foam structure. .

  The treatment for forming the specific surface layer is not particularly limited as long as the composition of the foam layer and the specific surface layer can be the same, for example, heat melting treatment, resin application, resin layer welding, For example, application of a resin film layer through an adhesive layer can be mentioned. Among them, it is not necessary to consider compatibility with other materials, and heat melting treatment is preferably used from the viewpoint of little change in thickness.

  Although it does not specifically limit as a heat-melting process, For example, the press process by a hot roll, a laser irradiation process, the contact melting process on the heated roll, a flame | frame process etc. are mentioned.

  In the case of press treatment with a hot roll, the treatment can be suitably performed using a thermal laminator or the like. Examples of the material of the roll include rubber, metal, and fluorine-based resin (for example, Teflon (registered trademark)).

  The temperature during the heat-melting treatment is not particularly limited, but it is 15 ° C. lower than the softening point or melting point of the resin constituting the resin foam (more preferably the resin foam) from the viewpoint of efficiently forming a specific surface layer. It is preferably at least 12 ° C. lower than the softening point or melting point of the resin constituting the resin, and more preferably 20 ° C. higher than the softening point or melting point of the resin constituting the resin foam. The temperature is preferably 10 ° C. or higher than the softening point or melting point of the resin. If the temperature during the heat-melting process is lower than the softening point or melting point of the resin constituting the resin foam by 15 ° C., the surface of the foam structure may not melt and a specific surface layer may not be obtained. is there. On the other hand, if the temperature during the heat-melting process is higher than a temperature 20 ° C. higher than the softening point or melting point of the resin constituting the resin foam, the foam structure may shrink and problems such as wrinkles may occur. .

  The treatment time for the heat-melting treatment is preferably about 0.1 to 10 seconds, and preferably about 0.5 to 7 seconds, although it depends on the treatment temperature. If the time is too short, melting of the surface of the foam structure does not proceed and a specific surface layer may not be obtained. On the other hand, if the time is too long, the foamed structure may shrink and problems such as wrinkles may occur.

  In addition, when applying a resin, welding a resin layer, and sticking a resin film layer through an adhesive layer, the above-mentioned used for obtaining a foam structure from the viewpoint of ease of obtaining the same composition and workability The resin composition is preferably used.

  The thickness and shape of the resin foam of the present invention are not particularly limited, and can be appropriately selected depending on the application. For example, the thickness of the resin foam can be selected from a range of about 0.2 to 5 mm (preferably 0.3 to 3 mm).

  Moreover, the resin foam may be processed into various shapes according to the apparatus used normally. At this time, processing, conveyance, and the like can be performed in a state where the resin foam is attached to the carrier tape (that is, the resin foam is held by the carrier tape as a foamed member laminate).

  Furthermore, the resin foam may be provided with an adhesive layer. In addition, when the adhesive layer is provided in the resin foam, it is not particularly limited, and the adhesive layer may be provided on a specific surface layer, or the adhesive layer is provided on the other surface layer. The pressure-sensitive adhesive layer may be provided on the foam layer.

  Since the resin foam retains a good foamed structure, it is processed into a predetermined shape, so that various members or parts are attached to (attached to) a predetermined part and are used as a dustproof material and a sealing material. It is preferably used as a shock absorbing material, a soundproofing material, a shock absorbing material or the like.

(Foamed member)
The foam member is a member composed of the resin foam, and an essential structure is a structure that can be held on the carrier tape with a specific surface layer of the resin foam. That is, the foam member is composed of the resin foam, and the specific surface layer of the resin foam is the outermost layer. Since it has such a configuration, the foamed member has good workability using a carrier tape, transportability using the carrier tape, foam breakage inhibiting property when peeling from the carrier tape, easy peelability from the carrier tape, etc. Demonstrate the characteristics of carrier tape (vs. carrier tape characteristics).

  Specifically, the foam member may be composed of only the resin foam, or the other surface of the resin foam (only one surface of the foam member is a surface provided by a specific surface layer). The other side of the case, either side of the foamed member when both sides are provided by a specific surface layer), and other layers and substrates (particularly adhesive layers, etc.) are laminated If the foamed member which may be configured has a configuration in which an adhesive layer is provided, for example, a processing mount can be provided or fixed or temporarily fixed to an adherend.

  The pressure-sensitive adhesive forming the pressure-sensitive adhesive layer is not particularly limited, and examples thereof include acrylic pressure-sensitive adhesives, rubber-based pressure-sensitive adhesives (natural rubber-based pressure-sensitive adhesives, synthetic rubber-based pressure-sensitive adhesives), silicone-based pressure-sensitive adhesives, and polyester-based pressure-sensitive adhesives. Known pressure-sensitive adhesives such as adhesives, urethane-based pressure-sensitive adhesives, polyamide-based pressure-sensitive adhesives, epoxy-based pressure-sensitive adhesives, vinyl alkyl ether-based pressure-sensitive adhesives, and fluorine-based pressure-sensitive adhesives can be appropriately selected and used. Further, the adhesive may be a hot melt adhesive. An adhesive can be used individually or in combination of 2 or more types. The pressure-sensitive adhesive may be any form of pressure-sensitive adhesive such as an emulsion-based pressure-sensitive adhesive, a solvent-based pressure-sensitive adhesive, an oligomer-based pressure-sensitive adhesive, or a solid-type pressure-sensitive adhesive. Among these, an acrylic pressure-sensitive adhesive is suitable as the pressure-sensitive adhesive from the viewpoint of preventing contamination of the adherend.

  The pressure-sensitive adhesive layer can be formed by using a known or conventional forming method. For example, a method of applying a pressure-sensitive adhesive on a predetermined site or surface (coating method), a pressure-sensitive adhesive film on a release film such as a release liner, etc. Examples thereof include a method (transfer method) of applying an agent to form an adhesive layer and then transferring the adhesive layer onto a predetermined site or surface. In forming the pressure-sensitive adhesive layer, a known or conventional coating method (such as a casting method, a roll coater method, a reverse coater method, a doctor blade method) can be appropriately used.

  The thickness of the adhesive layer is usually about 2 to 100 μm (preferably 10 to 100 μm). The thinner the adhesive layer, the higher the effect of preventing the adhesion of dust and dirt at the end, and thus the thinner the adhesive layer, the better. In addition, the adhesion layer may have any form of a single layer or a laminated body.

  Moreover, the adhesion layer may be formed on the foam through another layer (lower layer). Examples of such a lower layer include a base material layer (particularly a film layer), a nonwoven fabric layer, other adhesive layers, an intermediate layer, an undercoat layer, and the like.

  Furthermore, when the adhesive layer is formed on the other surface of the foamed member, on the adhesive layer, another layer, more specifically a release film (separator) (for example, release paper, release film, etc.), A substrate (for example, a paper-based substrate, a fiber-based substrate, a metal-based substrate, a plastic-based substrate such as a PET film), another adhesive layer, or the like may be formed.

  The foamed member may be processed so as to have a desired shape, thickness, or the like, and may be processed into various shapes according to the apparatus or device used. In addition, the foam member is suitably used as a dustproof material, a seal material, an impact absorbing material, a soundproof material, a cushioning material, or the like used when various members or parts are attached (attached) to a predetermined site.

(Foamed member laminate)
The foamed member laminate has a configuration in which the resin foam or the foamed member is held by a carrier tape having an adhesive layer on at least one side of the base material, and a specific surface layer of the resin foam And the pressure-sensitive adhesive layer of the carrier tape are in contact with each other and have a structure adhered to the carrier tape. Hereinafter, “resin foam or foam member” may be referred to as “resin foam (foam member)”.

  Thus, since the foamed member laminate has a configuration in which the resin foam (foamed member) is adhered to the adhesive surface of the carrier tape, the resin resin foam (foamed member) is placed on the carrier tape. Processing and transportation can be performed in a state of being adhered to the adhesive surface, and since a specific surface layer of the resin foam is adhered to the adhesive surface of the carrier tape, the resin foam (foam member) ) Can be used to suppress or prevent foam breakage and to easily peel the resin foam (foamed member) from the carrier tape.

  Using the foamed member laminate of the present invention, the resin foam (foamed member) is processed so as to have a predetermined shape, and then the resin foam (foamed member) is peeled off from the carrier tape. The body (foamed member) can be isolated. The resin foam (foamed member) isolated in this way is peeled off at the interface between the resin foam (foamed member) and the carrier tape, and there is no foam breakage that causes breakage in the foam structure. It does not occur, maintains a good foamed structure, and is processed into a predetermined shape. Therefore, a resin foam (foamed member) that has been processed and isolated using a foamed member laminate is a dustproof material, a sealing material, used when attaching (attaching) various members or parts to a predetermined site, It is useful as an impact absorbing material, a soundproofing material, a shock absorbing material and the like.

  The carrier tape is not particularly limited, but it is important to have an adhesive surface. The carrier tape exhibits an adhesive force (adhesive force) sufficient to hold the resin foam during processing and transport of the resin foam. It is important that the adhesive strength (adhesive strength) that can be easily peeled can be exhibited without destroying the surface of the foam.

  Accordingly, as the carrier tape, an adhesive tape or sheet having an adhesive layer with various adhesives can be used, and in particular, from the viewpoint of achieving both adhesiveness and releasability with a resin foam, (Meta) An acrylic pressure-sensitive adhesive tape or sheet having an acrylic pressure-sensitive adhesive layer made of an acrylic pressure-sensitive adhesive whose main component is an acrylic alkyl ester can be suitably used. As such an adhesive tape or sheet, a substrate-less type adhesive tape or sheet having a configuration in which an adhesive layer is formed on at least one surface of the substrate, or a substrate-less structure having a configuration formed only by the adhesive layer It may have any configuration of a type of adhesive tape or sheet.

  In the pressure-sensitive adhesive forming the pressure-sensitive adhesive layer, examples of the pressure-sensitive adhesive other than the acrylic pressure-sensitive adhesive include rubber-based pressure-sensitive adhesives (natural rubber-based pressure-sensitive adhesives, synthetic rubber-based pressure-sensitive adhesives), silicone-based pressure-sensitive adhesives, and polyester-based pressure-sensitive adhesives. Examples thereof include an adhesive, a urethane-based adhesive, a polyamide-based adhesive, an epoxy-based adhesive, a vinyl alkyl ether-based adhesive, and a fluorine-based adhesive. Further, the adhesive may be a hot melt adhesive. An adhesive can be used individually or in combination of 2 or more types. The pressure-sensitive adhesive may be any type of pressure-sensitive adhesive such as an emulsion-based pressure-sensitive adhesive, a solvent-based pressure-sensitive adhesive, an oligomer-based pressure-sensitive adhesive, and a solid pressure-sensitive adhesive.

  In addition, the base material in the adhesive tape or sheet is not particularly limited. For example, a plastic base material such as a plastic film or sheet; a paper base material such as paper; a fiber base material such as cloth, nonwoven fabric, or net. Metal bases such as metal foils and metal plates; rubber bases such as rubber sheets; foams such as foam sheets and laminates thereof (particularly, laminates of plastic bases and other bases) In addition, an appropriate thin leaf body such as a laminate of plastic films (or sheets) can be used.

  In addition, the thickness in particular of the base material in the adhesive tape or sheet | seat as a carrier tape, or an adhesive layer is not restrict | limited.

(Foamed materials for electrical and electronic equipment)
Since the resin foam and the foamed member of the present invention have a good foamed structure, they are used when attaching (attaching) various members or parts to a predetermined part by processing into a predetermined shape. It can be suitably used as a dustproof material, a sealing material, a shock absorbing material, a soundproofing material, a shock absorbing material and the like. In particular, even when a small member or member is mounted on a thin product, it can be suitably used.

  Various members or parts that can be attached (mounted) using the resin foam or foam member are not particularly limited, and examples thereof include various members or parts in electrical / electronic devices. Examples of such a member or component for an electric / electronic device include an image display member (particularly, a small-sized image display member) mounted on an image display device such as a liquid crystal display, an electroluminescence display, and a plasma display. Examples thereof include an optical member or an optical component such as a camera or a lens (particularly a small camera or lens) attached to a mobile communication device such as a “mobile phone” or a “portable information terminal”.

  The resin foam or foam member can also be used as a dustproof material for preventing toner from leaking from the toner cartridge. As described above, examples of the toner cartridge that can be attached using the foam member include a toner cartridge used in an image forming apparatus such as a copying machine or a printer.

(Electrical and electronic equipment)
The electrical / electronic devices of the present invention have a configuration in which the resin foam or foam member is used. In electric / electronic devices, the resin foam or foamed member is used as, for example, a dustproof material, a seal material, a shock absorber, a soundproof material, a shock absorber, or the like. Such electric / electronic devices usually have a configuration in which members or parts for electric / electronic devices are attached (attached) to a predetermined part via the resin foam or foam member. doing. Specifically, as electric / electronic devices, an image display device such as a liquid crystal display, an electroluminescence display, a plasma display or the like as an optical member or component (particularly, an image in which a small image display member is mounted as an optical member). Display device), and a camera or a lens (particularly a small camera or lens) having a configuration in which the resin foam or the foam member is attached (for example, a so-called “portable device”). Mobile communication devices such as “telephone” and “portable information terminal”). Such electric / electronic devices may be thinner than conventional products, and the thickness and shape thereof are not particularly limited.

  EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples.

(Measurement of L ^* (lightness))
Measurement was performed using a simple spectral color difference meter (device name “NF333” manufactured by Nippon Denshoku Industries Co., Ltd.).

発泡体表面の面積、及び発泡体表面に存在する孔の面積は、マイクロスコープ（装置名「ＶＨＸ６００」キーエンス社製）を用いて得られた測定サンプル表面の画像より求めた。
マイクロスコープによる観察では、照明方法として側射照明を採用し、その照度は１７０００ルクスとした。また、倍率は５００倍とした。
照明兼カメラとして、照明内蔵レンズカメラ（装置名「０Ｐ７２４０４」キーエンス社製」）を使用し、またレンズとして、ズームレンズ（商品名「ＶＨ−Ｚ１００」キーエンス社製）を使用した。
なお、照度は、照度計（商品名「ＶＨＸ６００」カスタム社製）を使用して調節した。 (Measurement of surface coverage)
The surface coverage was calculated from the formula (1).

The area of the surface of the foam and the area of the holes existing on the surface of the foam were determined from the image of the surface of the measurement sample obtained using a microscope (device name “VHX600”, manufactured by Keyence Corporation).
In observation with a microscope, side illumination was adopted as the illumination method, and the illuminance was 17000 lux. The magnification was 500 times.
A lens camera with built-in illumination (device name “0P72404” manufactured by Keyence Corporation) was used as the illumination and camera, and a zoom lens (trade name “VH-Z100” manufactured by Keyence Corporation) was used as the lens.
The illuminance was adjusted using an illuminometer (trade name “VHX600”, custom made).

(Production Example 1 of Foamed Structure)
Polypropylene [melt flow rate (MFR): 0.35 g / 10 min]: 45 parts by weight, polyolefin elastomer [melt flow rate (MFR): 6 g / 10 min, JIS A hardness: 79 °]: 55 parts by weight, carbon black ( Product name “Asahi # 35” manufactured by Asahi Carbon Co., Ltd .: 6 parts by weight and magnesium hydroxide as powdered flame retardant (average particle size: 0.7 μm): 10 parts by weight ) After kneading at a temperature of 200 ° C. in a twin-screw kneader manufactured by the company, it was extruded into a strand, cooled to water and formed into a pellet. The softening point of the pellet was 160 ° C.
The pellets were put into a single screw extruder manufactured by Nippon Steel Works, and carbon dioxide gas was injected under an atmosphere of 220 ° C. at a pressure of 22 (19 after injection) MPa. After sufficiently saturating the carbon dioxide gas, it was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a foam (foamed structure).
In this foam, the apparent density was 0.05 g / cm ³ and the thickness was 2.0 mm. The foam was sliced to obtain a foam having a thickness of 1.0 mm (referred to as “foam structure A”).

Example 1
Using a thermal laminator (apparatus name “MRK-6504” manufactured by MCK) with adjustable roll gap, the foamed structure A was subjected to the following conditions: gap: 1 mm, roll temperature: 150 ° C., processing speed: 8 m / min Then, a resin foam having a surface coverage of 49.2% was obtained by performing a surface heat melting treatment.

(Example 2)
Except that the gap was changed to 0.9 mm, surface heat melting treatment was performed in the same manner as in Example 1 to obtain a resin foam having a surface coverage of 62.1%.

(Example 3)
Except that the roll temperature was changed to 160 ° C., surface heat melting treatment was performed in the same manner as in Example 1 to obtain a resin foam having a surface coverage of 64.6%.

Example 4
Except that the gap was changed to 0.9 mm, surface heat melting treatment was performed in the same manner as in Example 3 to obtain a resin foam having a surface coverage of 75.4%.

(Example 5)
Except that the gap was changed to 0.8 mm, surface heat melting treatment was performed in the same manner as in Example 3 to obtain a resin foam having a surface coverage of 83.7%.

(Example 6)
Except that the roll temperature was changed to 170 ° C., a surface heat melting treatment was performed in the same manner as in Example 1 to obtain a resin foam having a surface coverage of 88.9%.

(Comparative Example 1)
The foam structure A was used as it was. The surface coverage of the foam structure A was 24.3%.

(Comparative Example 2)
Except that the roll temperature was changed to 140 ° C., a surface heat melting treatment was performed in the same manner as in Example 1 to obtain a resin foam having a surface coverage of 35.3%.

(Evaluation 1)
About an Example and a comparative example, the following measuring method or evaluation method measured or evaluated adhesive force and the presence or absence of foam destruction. The results are shown in Table 1.

(Adhesive force)
After storing the resin foam (width: 20 mm × length: 120 mm) for 24 hours or more in an atmosphere of temperature: 23 ± 2 ° C. and humidity: 50 ± 5 RH% (pretreatment conditions conform to JIS Z 0237) , Width: 30 mm x length: 120 mm carrier tape (trade name “SPV-AM-500” manufactured by Nitto Denko Corporation, single-sided adhesive tape with substrate, substrate: PET substrate), surface heat, In a form in which the melt-treated surface and the pressure-sensitive adhesive surface of the carrier tape are in contact with each other, the sample was pressure-bonded under conditions of a 2 kg roller and one reciprocation, and left for 24 hours to obtain a measurement sample.
A strongly adhesive double-sided adhesive tape (trade name “No. 500”) prevents the sample on the carrier tape substrate side of the measurement sample from floating and peeling off from a support plate (for example, a 2 mm thick bakelite plate) during measurement. The force required to peel off the resin foam from the carrier tape is fast peeling in an atmosphere of temperature: 23 ± 2 ° C and humidity: 50 ± 5RH%. The adhesive strength (N / 20 mm) was determined by measurement under each condition (tensile speed: 10 m / min) and low-speed peeling conditions (tensile speed: 0.3 m / min).
A high-speed peel tester (manufactured by Tester Sangyo Co., Ltd.) was used for measurement under high-speed peel conditions, and a universal tensile compression tester (device name “TCN-1kNB”, manufactured by Minebea Co., Ltd.) was used for measurements under low-speed peel conditions. .

(Presence or absence of foam destruction)
In the above measurement, in both the case of measuring under the high speed peeling condition and the case of measuring under the low speed peeling condition, the state of peeling was visually confirmed, and it was judged whether or not the surface destruction of the resin foam occurred.
In Table 1, “None” is described when there is no surface destruction of the resin foam, and “Yes” is described when surface destruction of the resin foam occurs.

  A sample for measurement at the time of adhesive strength measurement was prepared, and left for 24 hours in an atmosphere of temperature: 23 ± 2 ° C. and humidity: 50 ± 5 RH%, and then “floating” between the resin foam and the carrier tape・ When it was confirmed that there was no “peeling”, “floating / peeling” did not occur.

  As is clear from the examples and comparative examples, the peeling force from the carrier tape tended to increase as the surface coverage increased. Further, when surface heat melting treatment was performed under conditions that promoted heat treatment such as increasing the temperature or narrowing the gap, the surface coverage increased and the peel force also increased. Further, in the examples, the adhesive force under the low-speed peeling condition exceeds 0.3 N / 20 mm, so that the adhesive is obtained after fixing the foamed member obtained by laminating the adhesive layer on the resin foam to the carrier tape. When mounting a processing mount on the layer, processing and assembling the foamed member after finishing processing, if you try to peel the processing mount provided on the adhesive layer, the foaming member will peel off from the carrier tape Will not cause the problem of being unable to assemble. Furthermore, in the examples, since the surface coverage is 40% or more, it is possible to achieve both foam destruction inhibiting properties when peeling from the carrier tape and adhesion to the carrier tape.

  The examples could be produced by a simple process called surface heat melting treatment, and physical properties did not change before and after the surface heat melting treatment. Moreover, foam destruction did not occur at the time of peeling, and the integrity was good.

(Evaluation 2)
FIG. 1 shows the FT-IR chart of the surface subjected to the surface heat melting treatment of Example 1 and the FT-IR chart of the cut surface cut at half the thickness. The surface subjected to the surface heat melting treatment is a surface provided by the surface layer, and the cut surface cut by half the thickness is a surface provided by the foam layer. In addition, said "cut surface cut | disconnected by the half thickness" is a cut surface of the direction orthogonal to thickness direction.
The measurement was performed by installing a silver gate (Ge45 ·) manufactured by Specac for single reflection ATR measurement in “FT-IR spectrum meter SPECTRUM2000” manufactured by Perkin Elmer. The sample was sufficiently covered with the entire surface of the Ge crystal, and a silicon rubber having a thickness of 1 mm or more was sandwiched between the sample and the presser so that the sample was sufficiently adhered to the Ge crystal. The resolution was 4 cm ⁻¹ and the number of integrations was 16 times.

  In the chart when the FT-IR analysis of FIG. 1 is performed, the main absorption is the same. For this reason, the main polymer components of the foam layer portion and the surface layer portion were the same, and the composition of the surface layer and the foam layer could be evaluated to be the same.

  Further, in the other examples, as described above, the FT-IR analysis was performed on the cut surface cut at half the thickness and the surface subjected to the surface heat melting treatment. -An IR chart could be obtained. For this reason, also in the other Examples, the main polymer components of the foam layer portion and the surface layer portion were the same, and the composition of the surface layer and the foam layer could be evaluated to be the same.

Claims (14)

A resin foam having a foam layer and a surface layer, wherein the foam layer and the surface layer have the same composition, and the surface coverage (defined by the formula (1)) of the surface layer is 40% or more. And

The foam layer has a density of 0.20 g / cm ³ or less;
The resin constituting the resin foam is a thermoplastic resin,
The surface layer is formed by heat melting treatment,
The thickness of the resin foam is 0.2 to 5 mm,
Resin foam for use in electrical and electronic equipment.   The resin foam according to claim 1, wherein the thermoplastic resin is a polyolefin resin.   The resin foam according to claim 1 or 2, wherein the temperature of the heat-melting treatment is equal to or higher than a temperature defined by [(softening point or melting point of the resin constituting the resin foam) -15 ° C].   The resin foam according to any one of claims 1 to 3, wherein the resin foam is formed through a step of reducing pressure after impregnating a resin with a high-pressure gas.   The resin foam according to claim 4, wherein the gas is an inert gas.   The resin foam according to claim 5, wherein the inert gas is carbon dioxide.   The resin foam according to claim 4, wherein the high-pressure gas is in a supercritical state.   The resin foam according to claim 1, which has a closed cell structure or a semi-continuous semi-closed cell structure.   The foam member in which the resin foam of any one of Claims 1-8 is used.   The foam member according to claim 9, wherein the foam layer has the surface layer on one side and an adhesive layer on the other side.   The foamed member according to claim 10, wherein the pressure-sensitive adhesive layer is an acrylic pressure-sensitive adhesive layer.   The foam member according to any one of claims 9 to 11, which is used for an electric / electronic device.   The resin foam is a foamed member laminate having a configuration in which the resin foam is held by a carrier tape having an adhesive layer on at least one side of the base material, and the resin foam according to any one of claims 1 to 7. The resin foam is a structure in which the resin foam is held by a carrier tape. The resin foam is adhered to the carrier tape in a form in which the surface layer and the adhesive layer of the carrier tape are in contact with each other. A foamed member laminate having the above structure.   An electronic / electric device using a foam member, wherein the foam member is a foam member for an electric / electronic device according to claim 13.

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