TW201406837A - Resin foam and foam member - Google Patents

Abstract

Provided is a resin foam having excellent dust-proof characteristics and excellent flexibility. This resin foam is characterized by: having an instantaneous recovery rate, as defined, of at least 50%; having a repulsive force at 50% compression of 0.1-4.0 N/cm2; having an average cell diameter of 10-150 [mu]m; and having a maximum cell diameter of no more than 300 [mu]m. Instantaneous recovery rate: The ratio between the thickness of the initial state and the thickness of a sheet resin foam after the compression thereof for one minute in the thickness direction and in an atmosphere of 23 DEG C, such that the thickness thereof is 20% of the initial thickness, then the release of the compressed state in an atmosphere of 23 DEG C, said thickness being measured at 0.6 s after the release of the compressed state.

Description

Resin foam and foam member

The present invention relates to a resin foam and a foamed member. More specifically, the present invention relates to a resin foam and a foam member which have excellent dust resistance and excellent flexibility.

In electrical or electronic equipment (eg, mobile phones, mobile terminals, smart phones, tablet PCs (tablet PCs), digital cameras, video cameras, digital video cameras, personal computers, home appliances, etc.), will be fixed to the liquid crystal display (LCD) Liquid crystal display), an image display device such as an electroluminescence display or a plasma display device, or an optical member such as a camera or a lens is fixed to a specific portion (fixed portion, etc.), and a foam material is used. [Laminate and foam sealing material in which an adhesive layer is laminated on at least one side of the foamed structure (foam)].

Examples of the use form of the foam material include a shock absorbing material (gas shims) (a vibration absorbing material for a mobile phone) around a display of a mobile phone (for example, an LCD or the like). When the vibration-damping material for a mobile phone is, for example, a sheet having a thickness of about 1 mm, it is punched into a frame shape having a width of 1 to 2 mm, and then fixed to a container (case, casing, etc.) by a double-sided tape, and compressed 30~ Use about 50%. In this type of use, it is required to have not only the function of the vibration absorbing material that protects the display from being damaged when the mobile phone is dropped, but also the dustproof or airtightness that prevents the dust from entering the display portion (for example, the LCD portion). performance.

As the gasket, a gasket containing a polyurethane foam having a density of 0.3 to 0.5 g/cm ³ is known (see Patent Document 1). However, this gasket prevents the shake of the liquid crystal display screen by suppressing the expansion ratio, and the flexibility and cushioning property are insufficient.

Further, foaming and dustproofing of a foam having an average cell diameter of 10 to 90 μm, a compression resistance of 50% and a repulsive load of 0.1 to 3.0 N/cm ² and an apparent density of 0.01 to 0.10 g/cm ^{3 is known} . A material (see Patent Document 2), and a polyester-based elastomer foam formed by foaming a specific polyester-based elastomer composition having a density of 0.03 to 0.15 g/cm ³ (Patent Document 3).

[Previous Technical Literature] [Patent Literature]

Patent Document 1: Japanese Patent Laid-Open No. 2001-100216

Patent Document 2: Japanese Patent Laid-Open Publication No. 2009-293043

Patent Document 3: Japanese Patent Laid-Open Publication No. 2008-45120

In the foamed dustproof material or the foamed body, it is required to further reduce the stress relaxation property in terms of further improving the recovery property from the deformation at the time of the impact load. Its purpose is to further improve dust resistance. For example, in a machine having a display unit to which a foaming and dustproof material is applied, when the machine is subjected to an impact due to dropping, if the strain recovery property of the foamed dustproof material is slow, the deformation of the foamed dustproof material cannot follow the deformation of the display. On the other hand, a gap is formed between the foamed dustproof material and the display, and when dust or the like is present, there is a fear that the dust intrudes into the inside of the machine.

Further, in the foaming dustproof material or the foam, the generation of coarse cells in the bubble structure (cell structure) is further suppressed, and dust or water is prevented from entering from the coarse cell portion, and it is required to further improve the sealing property.

Accordingly, an object of the present invention is to provide a resin foam which has excellent dust resistance and excellent flexibility.

Further, another object of the present invention is to provide an excellent dustproof property, and A foamed member having excellent flexibility.

Therefore, the inventors of the present invention conducted an effort to find that when the instantaneous recovery rate is set to a specific value or more in the resin foam, the rebound force at a compression of 50% is set within a specific range, and the average cell diameter is set. When the maximum cell diameter is set to a specific value or less within a specific range, excellent dust resistance and excellent flexibility are exhibited. The present invention is based on such insights.

That is, the present invention provides a resin foam characterized in that the instantaneous recovery rate as defined below is 50% or more, the rebound force at a compression of 50% is 0.1 to 4.0 N/cm ² , and the average cell diameter is 10 ~150 μm, the maximum cell diameter is 300 μm or less.

Instant recovery rate: For a sheet-like resin foam, it is compressed in the thickness direction for 1 minute so that the thickness becomes 20% of the initial thickness in a 23 ° C environment, and then the compressed state is released in a 23 ° C environment, and the self-compressed state is released. The ratio of the thickness to the initial thickness after 0.6 seconds from the release.

The resin foam preferably further has an apparent density of 0.01 to 0.20 g/cm ³ .

The resin constituting the above resin foam is preferably a thermoplastic resin.

The above thermoplastic resin is preferably a polyester.

The resin foam is preferably formed by a step of impregnating a resin composition with a high-pressure inert gas and then reducing the pressure.

It is preferable that the resin foam is formed by foaming by subjecting an inert gas having a high pressure to an unfoamed molded article containing the resin composition, followed by depressurization.

The resin foam is preferably formed by foaming by subjecting a high-pressure inert gas to a molten resin composition and then performing a pressure reduction step.

The resin foam is preferably formed by a step of depressurizing a high-pressure inert gas, followed by heating.

The above inert gas is preferably carbon dioxide gas.

The high pressure inert gas is preferably in a supercritical state.

Furthermore, the present invention provides a foamed member comprising the above resin foam.

It is preferable that the foam member has an adhesive layer on the resin foam.

The pressure-sensitive adhesive layer is preferably formed on the resin foam by a separator layer.

The above adhesive layer is preferably an acrylic adhesive layer.

The resin foam of the present invention is excellent in dustproofness and excellent in flexibility.

Further, since the foamed member of the present invention contains the above resin foam, it is excellent in dustproofness and excellent in flexibility.

1‧‧‧Sample for measurement

2‧‧‧Evaluation container with sample for measurement

22‧‧‧Sample for measurement

23‧‧‧Aluminum plate

24‧‧‧Base plate

25‧‧‧Powder Supply Department

26‧‧‧ screws

27‧‧‧Foam compression plate

28‧‧‧Flap fixing accessories

211‧‧‧Black acrylic plate (black acrylic plate on the cover side)

212‧‧‧Black acrylic plate (black acrylic plate on the aluminum side)

Fig. 1 is a schematic plan view showing a sample for measurement used for measuring dust resistance.

2 is an end view of the A-A' wire cutting portion of the evaluation container for measuring the dustproofness of the sample for measurement.

Fig. 3 is a schematic plan view of an evaluation container for measuring dust resistance of a sample for measurement.

In the resin foam of the present invention, the instantaneous recovery rate as defined below is 50% or more, the rebound force at 50% compression is 0.1 to 4.0 N/cm ² , and the average cell diameter is 10 to 150 μm. The pore diameter is 300 μm or less.

Instant recovery rate: For a sheet-like resin foam, it is compressed in the thickness direction for 1 minute so that the thickness becomes 20% of the initial thickness in a 23 ° C environment, and then the compressed state is released in a 23 ° C environment, and the self-compressed state is released. The ratio of the thickness to the initial thickness after 0.6 seconds from the release.

Further, in the present specification, the instantaneous recovery rate defined above may be simply referred to as "instantaneous recovery rate".

The resin foaming system of the present invention is formed by foaming a composition (resin composition) containing at least a resin constituting the resin foam of the present invention. Further, the resin composition preferably contains 70% by weight or more (preferably 80% by weight or more) based on the total amount of the resin composition (100% by weight).

The instantaneous recovery rate of the resin foam of the present invention is 50% or more, preferably 65% or more, more preferably 70% or more, still more preferably 75% or more. In the resin foam of the present invention, since the instantaneous recovery rate is 50% or more, it has excellent dustproofness. In the resin foam of the present invention, since the instantaneous recovery rate is 50% or more, for example, when the resin foam of the present invention is used as a sealing material, even if it is subjected to impact during a fall or collision, deformation of the sealing portion occurs. It can instantly follow the impact and restore deformation, maintaining the seal. Further, in the case of sluggish recovery, the sealing is insufficient and dust or dust is easily invaded.

The resilience of the resin foam of the present invention at 50% compression is 0.1 to 4.0 N/cm ² , preferably 0.2 to 3.5 N/cm ² , more preferably 0.3 to 3.0 N/cm ² . In the resin foam of the present invention, since the repulsive force at a compression of 50% is 0.1 N/cm ² or more, appropriate rigidity can be obtained, and good workability can be obtained. Further, since the rebound force at the time of compression of 50% is 4.0 N/cm ² or less, it has excellent flexibility. Further, the repulsive force at the time of compression of 50% is defined as the repulsion load when the resin foam is compressed in the thickness direction so as to have a thickness of 50% of the initial thickness in an environment of 23 ° C. Further, in the case of the present application, the case of merely "reducing the rebound force at 50%" means the rebound force at the time of compression of 50% according to the definition.

The resin foam of the present invention has an average cell diameter of 10 to 150 μm, preferably 20 to 150 μm, more preferably 25 to 125 μm, still more preferably 30 to 100 μm. In the resin foam of the present invention, since the average cell diameter is 10 μm or more, it has excellent flexibility. Moreover, since the average cell diameter is 150 μm or less, generation of voids can be suppressed, and excellent dust resistance can be obtained.

The resin foam of the present invention has a maximum cell diameter of 300 μm or less, more preferably 250. It is preferably not more than μm, more preferably not more than 200 μm. In the resin foam of the present invention, since the maximum cell diameter is 300 μm or less, the cell structure is excellent in uniformity and does not contain coarse cells, so that dust can be prevented from entering from the coarse cells and the dustproof property is lowered. The problem is excellent in sealing or dustproofness.

The cell diameter in the cell structure of the resin foam of the present invention is obtained, for example, by obtaining an enlarged image of a cell structure portion (bubble structure portion) of a cut surface by a digital microscope, and determining a bubble. The area of the hole is converted to the diameter of the approximate circle.

In the resin foam of the present invention, since the average cell diameter is 10 to 150 μm and the maximum cell diameter is 300 μm or less, it has a uniform and fine cell structure. Also, it does not contain coarse cells.

The cell structure of the resin foam of the present invention is not particularly limited, and in order to impart flexibility, a semi-continuous semi-closed cell structure (cell structure in which a closed cell structure and a continuous cell structure are mixed) is preferable. In particular, it is preferable that the closed cell structure portion in the resin foam has a cell structure of 40% or less (preferably 30% or less).

The apparent density of the resin foam of the present invention is not particularly limited, but is preferably 0.01 to 0.20 g/cm ³ , more preferably 0.02 to 0.17 g/cm ³ , still more preferably 0.03 to 0.15 g/cm ³ . In the resin foam of the present invention, when the density is 0.01 g/cm ³ or more, good strength can be obtained. Moreover, when the density is 0.20 g/cm ³ or less, a high expansion ratio is obtained, and excellent flexibility can be obtained. In other words, in the resin foam of the present invention, when the apparent density is 0.01 to 0.20 g/cm ³ , better foaming properties (high expansion ratio) can be obtained, so that it is easy to exhibit appropriate strength and excellent properties. Softness and excellent cushioning properties.

The shape of the resin foam of the present invention is not particularly limited, but is preferably a sheet shape or a belt shape. Moreover, it can also be processed into an appropriate shape according to the purpose of use. For example, it may be processed into a linear shape, a circular shape or a polygonal shape, a frame shape (frame shape), or the like by cutting, punching, or the like.

The thickness of the resin foam of the present invention is not particularly limited, but is preferably 0.05 to 3.0. Mm is more preferably 0.06 to 2.8 mm, further preferably 0.07 to 1.5 mm, and particularly preferably 0.08 to 1.0 mm.

The resin which is a raw material of the resin foam of the present invention is not particularly limited, and a thermoplastic resin is preferably used. The resin foam of the present invention may be composed of only one type of resin, or may be composed of two or more kinds of resins.

Examples of the thermoplastic resin include low density polyethylene, medium density polyethylene, high density polyethylene, linear low density polyethylene, polypropylene, a copolymer of ethylene and propylene, ethylene or propylene and other α-olefins (for example). a copolymer of butene-1, pentene-1, hexene-1, 4-methylpentene-1, etc., ethylene and other ethylenically unsaturated monomers (for example, vinyl acetate, acrylic acid, acrylate) a polyolefin resin such as a copolymer of methacrylic acid, methacrylic acid ester or vinyl alcohol; styrene such as polystyrene or acrylonitrile-butadiene-styrene copolymer (ABS (Acrylonitrile Butadiene Styrene) resin) Resin; 6-nylon, 66-nylon, 12-nylon and other polyamine resin; polyamidoquinone; polyurethane; polyimine; polyether quinone; polymethacrylic acid Acrylic resin such as methyl ester; polyvinyl chloride; polyvinyl fluoride; alkenyl aromatic resin; polyester resin such as polyethylene terephthalate or polybutylene terephthalate; bisphenol A polycarbonate Polycarbonate such as ester; polyacetal; polyphenylene sulfide. Further, the thermoplastic resin may be used singly or in combination of two or more. Further, when the thermoplastic resin is a copolymer, it may be a copolymer of any of a random copolymer and a block copolymer.

The thermoplastic resin also contains a rubber component and/or a thermoplastic elastomer component. Since the rubber component or the thermoplastic elastomer component is at room temperature or lower (for example, 20° C. or lower), the flexibility and shape followability of the resin foam are remarkably excellent. Further, the resin foaming system of the present invention may be formed of a resin composition containing the above thermoplastic resin and a rubber component and/or a thermoplastic elastomer component.

The rubber component or the thermoplastic elastomer component is not particularly limited as long as it has rubber elasticity and can be foamed, and examples thereof include natural rubber, polyisobutylene, and polyisomeric rubber. Natural or synthetic rubber such as pentadiene, chloroprene rubber, butyl rubber, nitrile rubber; ethylene-propylene copolymer, ethylene-propylene-diene copolymer, ethylene-vinyl acetate copolymer, polybutene, An olefin-based elastomer such as chlorinated polyethylene; a styrene-based elastomer such as a styrene-butadiene-styrene copolymer, a styrene-isoprene-styrene copolymer, or a hydride thereof; a polyester system Various thermoplastic elastomers such as an elastomer; a polyamide-based elastomer; a polyurethane-based elastomer. In addition, these rubber components or thermoplastic elastomer components may be used alone or in combination of two or more.

The thermoplastic resin is preferably a polyester (in view of obtaining an instantaneous recovery ratio of a specific value or more and a repulsive force at a compression of 50% in a specific range, and obtaining excellent flexibility and excellent dust resistance. A polyester such as an ester resin or a polyester elastomer is more preferably a polyester elastomer. In other words, the resin foam of the present invention is more preferably a resin foam (polyester elastomer foam) formed of a resin composition containing a polyester elastomer.

The polyester-based elastomer is not particularly limited as long as it is a resin having an ester bond site formed by a reaction (polycondensation) of a polyol component and a polycarboxylic acid component, and examples thereof include an aromatic dicarboxylic acid (II). A polyester-based thermoplastic resin obtained by polycondensation of a valence aromatic carboxylic acid) and a diol component.

Examples of the aromatic dicarboxylic acid include terephthalic acid, isophthalic acid, phthalic acid, and naphthalenecarboxylic acid (for example, 2,6-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, etc.). Diphenyl ether dicarboxylic acid, 4,4'-biphenyldicarboxylic acid, and the like. Further, the aromatic dicarboxylic acid system may be used singly or in combination of two or more kinds.

Further, examples of the diol component include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, 2-methyl-1,3-propanediol, and 1,5- Pentandiol, 2,2-dimethyl-1,3-propanediol (neopentyl glycol), 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl- 2,4-pentanediol, 1,7-heptanediol, 2,2-diethyl-1,3-propanediol, 2-methyl-2-propyl-1,3-propanediol, 2-methyl -1,6-hexanediol, 1,8-octanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,3,5-trimethyl-1,3-pentanediol 1,9-nonanediol, 2,4-diethyl- 1,5-pentanediol, 2-methyl-1,8-octanediol, 1,10-nonanediol, 2-methyl-1,9-nonanediol, 1,18-octadecane An aliphatic diol such as an alcohol or a dimer; 1,4-cyclohexanediol, 1,3-cyclohexanediol, 1,2-cyclohexanediol, 1,4-cyclohexanedimethanol, 1, An alicyclic diol such as 3-cyclohexanedimethanol or 1,2-cyclohexanedimethanol; an ethylene oxide adduct of bisphenol A, bisphenol A, an epoxide of bisphenol S or bisphenol S An ethane adduct, an aromatic diol such as phthalic diol or naphthalene diol; an ether diol such as diethylene glycol, triethylene glycol, tetraethylene glycol, polyethylene glycol or dipropylene glycol; Alcohol content, etc. Further, the diol component may be a diol component in a polymer form such as a polyether diol or a polyester diol. Examples of the polyether diol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, which are subjected to ring-opening polymerization of ethylene oxide, propylene oxide, tetrahydrofuran, and the like, and copolyethers obtained by copolymerizing the same. Polyether glycol and the like. Further, the diol component may be used singly or in combination of two or more.

Examples of the polyester-based thermoplastic resin include polyethylene terephthalate, polytrimethylene terephthalate, polybutylene terephthalate, polyethylene naphthalate, and polynaphthalene dicarboxylic acid. A polyalkylene terephthalate resin such as butadiene ester or polycyclohexane terephthalate. Further, a copolymer obtained by copolymerizing two or more kinds of the above polyalkylene terephthalate resins may be used. Further, when the polyalkylene terephthalate resin is a copolymer, it may be a copolymer of any of a random copolymer, a block copolymer, and a graft copolymer.

Further, examples of the polyester-based elastomer include a polyester-based elastomer which is a block copolymer of a hard segment and a soft segment. In particular, as the polyester-based elastomer, in order to obtain an instantaneous recovery rate of a specific value or more, it is preferable that the elastic modulus is large, and in order to obtain a rebounding force at a compression of 50% in a specific range, it is preferable that the flexibility is higher. The larger one is therefore preferably a polyester-based elastomer which has both of these properties as a block copolymer of a hard segment and a soft segment.

Examples of the polyester elastomer (the polyester elastomer which is a block copolymer of a hard segment and a soft segment) include (i) the above aromatic dicarboxylic acid and the above diol component. a polyester formed by polycondensation of a diol component having a carbon number of 2 to 4 in a main chain between a hydroxyl group and a hydroxyl group is a hard segment and a hydroxyl group of the above aromatic dicarboxylic acid and the above diol component a polyester formed by polycondensation of a diol component having a carbon number of 5 or more in a main chain between hydroxyl groups is a polyester/polyester copolymer of a soft segment; (ii) will be as described above (i) The same polyester is set as a hard segment and the polyether such as the above polyether diol is a soft segment of the polyester ‧ polyether copolymer; (iii) will be the same as (i) and (ii) above The polyester is a hard segment and the aliphatic polyester is a soft segment of a polyester ‧ polyester copolymer or the like.

In particular, when the resin foam of the present invention is a polyester elastomer foam, the polyester elastomer to be formed is preferably a block copolymer as a hard segment and a soft segment. The polyester-based elastomer is more preferably a copolymer of the above-mentioned (ii) polyester ‧ polyether type (the carbon number in the main chain between the aromatic dicarboxylic acid and the hydroxyl group and the hydroxyl group is 2 to 4) The polyester formed by the polycondensation of the alcohol component is a polyester ‧ polyether copolymer having a hard segment and a polyether as a soft segment.

The polyester ‧ polyether type copolymer of the above (ii), more specifically, a polyester ‧ polyether having a polybutylene terephthalate as a hard segment and a polyether as a soft segment Type block copolymer and the like.

The melt flow rate (MFR, Melt Flow Rate) of the resin constituting the resin foam of the present invention at 230 ° C is not particularly limited, but is preferably 1.5 to 4.0 g/10 min, more preferably 1.5 to 3.8 g/10 min. Further preferably, it is 1.5 to 3.5 g/10 min. When the melt flow rate (MFR) of the resin at 230 ° C is 1.5 g/10 min or more, the moldability of the resin composition is improved, which is preferable. For example, it is preferable since the extruder can be easily extruded in a desired shape without stopping. Further, if the melt flow rate (MFR) of the resin at 230 ° C is 4.0 g/10 min or less, it is difficult to cause a deviation of the cell diameter after the cell structure (bubble structure) is formed, and a uniform cell structure is easily obtained. ideal. In the present specification, the MFR at 230 ° C means the MFR measured at a temperature of 230 ° C and a load of 2.16 kgf based on ISO 1133 (JIS K 7210).

That is, the resin foam of the present invention is preferably formed of a resin composition containing a resin having a melt flow rate (MFR) of from 230 to 4.0 g/10 min at 230 °C. In particular, in the case where the resin foam of the present invention is a polyester elastomer foam, it is preferably a polyester system containing a melt flow rate (MFR) at 230 ° C of 1.5 to 4.0 g/10 min. A resin composition of an elastomer (particularly, a polyester elastomer which is a block copolymer of a hard segment and a soft segment).

The resin composition forming the resin foam of the present invention preferably contains a foaming nucleating agent in addition to the above resin. When the resin composition contains a foaming nucleating agent, it is easy to obtain a resin foam having a good foaming state. Further, the foaming nucleating agent may be used singly or in combination of two or more.

The foaming nucleating agent is not particularly limited, and an inorganic material can be preferably used. Examples of the inorganic substance include hydroxides such as aluminum hydroxide, potassium hydroxide, calcium hydroxide, and magnesium hydroxide; clay (especially hard clay); talc; cerium oxide; zeolite; for example, calcium carbonate and magnesium carbonate. An alkaline earth metal carbonate; for example, a metal oxide such as zinc oxide, titanium oxide or aluminum oxide; for example, various metal powders such as iron powder, copper powder, aluminum powder, nickel powder, zinc powder, titanium powder, alloy powder, etc. Metal powder; mica; carbon particles; glass fiber; carbon tube; layered niobate; glass.

Among them, as the inorganic substance as the foaming nucleating agent, the generation of coarse cells is suppressed, and a uniform and fine cell structure can be easily obtained, and clay, alkaline earth metal carbonate, and more preferably hard clay are preferable. .

The above hard clay system contains almost no clay of coarse particles. In particular, the hard clay is preferably a clay having a mesh residue of 0.01% or less of 0.01%, more preferably 0.001% or less of clay having a mesh residue of 0.001% or less. Further, the sieve residue (screen residue) is a ratio (weight basis) of the residue to the whole when it is sieved by a sieve.

The hard clay is composed of alumina and cerium oxide as essential components. The total ratio of alumina and yttrium oxide in the above hard clay is relative to the total amount of the above hard clay (100 weight The amount %) is preferably 80% by weight or more (for example, 80 to 100% by weight), more preferably 90% by weight or more (for example, 90 to 100% by weight). Further, the hard clay may be calcined.

The average grain diameter of the hard clay is not particularly limited, but is preferably 0.1 to 10 μm, more preferably 0.2 to 5.0 μm, still more preferably 0.5 to 1.0 μm.

Further, the inorganic material is preferably subjected to surface processing. That is, the foaming nucleating agent is preferably a surface-treated inorganic substance. The surface treatment agent used for the surface treatment of the inorganic material is not particularly limited, and the affinity for the resin (especially polyester) is improved by performing the surface treatment, and foaming, molding, and the like are obtained. An aluminum compound, a decane compound, a titanate compound, or an epoxy compound is preferable in terms of an effect of not forming voids during mixing, stretching, and the like, and foaming at the time of foaming. Further, an isocyanate compound, a higher fatty acid or a salt thereof, and a phosphate ester may more preferably be a decane compound (particularly a decane coupling agent), a higher fatty acid or a salt thereof (especially stearic acid). In addition, the surface treatment agent may be used alone or in combination of two or more.

That is, the surface treatment of the above inorganic substance is preferably a decane coupling treatment or a treatment using a higher fatty acid or a salt thereof.

The aluminum compound is not particularly limited, and is preferably an aluminum coupling agent. Examples of the aluminum-based coupling agent include aluminum acetaloxydiisopropylate, aluminum ethoxide, aluminum isopropoxide, aluminum mono-t-butoxydiisopropylate, aluminum second butoxide, and acetamidine. Ethyl acetate diisopropoxide aluminum, tris(acetonitrile ethyl acetate) aluminum, monoethyl acetonacetone bis(acetonitrile ethyl acetate) aluminum, tris(acetonitrile)aluminum, isopropyl acid cycloaluminum oxide (Cyclic Aluminum Oxide Isopropylate), Cyclic Aluminum Oxide Isostearate, and the like.

The decane-based compound is not particularly limited, and is preferably a decane-based coupling agent. Examples of the decane-based coupling agent include a vinyl-containing decane-based coupling agent, a (meth)acryl-based decane-based coupling agent, an amine-containing decane-based coupling agent, and an epoxy group-containing decane-based coupling agent. Mixture, decane-based coupling agent containing sulfhydryl group, decane system containing carboxyl group A coupling agent, a decane coupling agent containing a halogen atom, or the like. Specific examples of the decane coupling agent include vinyl trimethoxy decane, vinyl ethoxy decane, dimethyl vinyl methoxy decane, dimethyl vinyl ethoxy decane, and methyl ethylene. Dimethoxy decane, methyl vinyl diethoxy decane, vinyl tris(2-methoxy) decane, vinyl triethoxy decane, 2-methyl propylene methoxyethyl three Ethoxy decane, 3-methacryloxypropyltrimethoxydecane, 3-methylpropenyloxypropyltriethoxydecane, 3-methylpropenyloxy-propylmethyldi Methoxydecane, 3-aminopropyltrimethoxydecane, 3-aminopropyltriethoxydecane, 2-aminoethyltrimethoxydecane, 3-[N-(2-amino) Amino]propyltrimethoxydecane, 3-[N-(2-aminoethyl)amino]propyltriethoxydecane, 2-[N-(2-aminoethyl)amine Ethyltrimethoxydecane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxydecane, 2-(3,4-epoxycyclohexyl)ethyltriethoxydecane, 3- Glycidoxy-propyltrimethoxydecane, 3-glycidoxy-propylmethyldiethoxyfluorene , 2-glycidoxy-ethyltrimethoxydecane, 2-glycidoxy-ethyltriethoxydecane, 3-mercaptopropyltrimethoxydecane, carboxymethyltriethoxydecane, 3 -Carboxypropyltrimethoxydecane, 3-carboxypropyltriethoxydecane, and the like.

The titanate-based compound is not particularly limited, and is preferably a titanate-based coupling agent. Examples of the titanate coupling agent include isopropyl triisostearate isopropyl titanate, isopropyl tris(dioctylpyrophosphonium oxy)titanate, and tris(N-aminoethyl- Isopropyl ethyl) isopropyl titanate, isopropyl tridecyl benzene sulfonyl titanate, tetraisopropyl bis(dioctylphosphonium oxy) titanate, tetraoctyl bis (two) -tridecylphosphonium oxy) titanate, tetrakis(2,2-diallyloxymethyl-1-butyl)bis(di-tridecyl)phosphite-titoxytitanate Ester, bis(dioctylpyridiniumoxy)glycolic acid titanate, bis(dioctylpyridiniumoxy)ethene titanate, trioctylphosphonium titanate, dimethyl methacrylate Isopropyl stearyl phthalate, isopropyl isostearyl bis propylene methacrylate, isopropyl tris(dioctylphosphonium oxy) titanate, triisopropylphenyl phenyl titanic acid Isopropyl ester, dicumylphenyl hydroxyglycolate titanate, diisostearate vinyl titanate, and the like.

The epoxy compound is not particularly limited, and is preferably an epoxy resin or a monoepoxy compound. Examples of the epoxy resin include a glycidyl ether epoxy resin such as a bisphenol A epoxy resin, a glycidyl ester epoxy resin, a glycidylamine epoxy resin, and an alicyclic epoxy resin. . Further, examples of the monoepoxy compound include styrene oxide, glycidyl phenyl ether, allyl glycidyl ether, glycidyl (meth)acrylate, and 1,2-epoxycyclohexane. , epichlorohydrin, deglycerin, etc.

The isocyanate compound is not particularly limited, and is preferably a polyisocyanate compound or a monoisocyanate compound. Examples of the polyisocyanate-based compound include aliphatic diisocyanates such as tetramethylene diisocyanate and hexamethylene diisocyanate; and alicyclic groups such as isophorone diisocyanate and 4,4′-dicyclohexylmethane diisocyanate; Diisocyanate; diphenylmethane diisocyanate, 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, phenylene diisocyanate, 1,5-naphthalene diisocyanate, benzene dimethylene diisocyanate, tolyl An aromatic diisocyanate such as a diisocyanate; a polymer having a free isocyanate group formed by the reaction of the diisocyanate compound and a polyol compound. Further, examples of the monoisocyanate compound include phenyl isocyanate and stearyl isocyanate.

Examples of the higher fatty acid or a salt thereof include higher fatty acids such as oleic acid, stearic acid, palmitic acid, and lauric acid, and salts of the higher fatty acid (for example, metal salts). Examples of the metal atom in the metal salt of the above-mentioned higher fatty acid include an alkali metal atom such as a sodium atom or a potassium atom, and an alkaline earth metal atom such as a magnesium atom or a calcium atom.

The above phosphates are preferably partial esters of phosphoric acid. Examples of the above-mentioned phosphoric acid partial esters include a partial ester of phosphoric acid (monoesterified or diesterified) partially phosphoric acid (such as orthophosphoric acid), or a partial ester of the phosphoric acid. Salt (using a metal salt such as an alkali metal or the like) or the like.

The method for surface-treating the inorganic material by the surface treatment agent is not particularly limited, and examples thereof include a dry method, a wet method, and an overall blending method. In addition, the amount of the surface treatment agent in the surface treatment of the inorganic material by the surface treatment agent is not particularly limited, and is preferably 0.1 to 10 parts by weight, more preferably 0.3 to 8 parts by weight, per 100 parts by weight of the inorganic substance.

Further, the 166 mesh residue of the inorganic material is not particularly limited, but is preferably 0.01% or less, more preferably 0.001% or less. The reason for this is that when the resin composition is foamed, if coarse particles are present, foaming of the cells is likely to occur. It is caused by the size of the particles exceeding the thickness of the cell walls.

The average grain diameter of the inorganic substance is not particularly limited, but is preferably 0.1 to 10 μm, more preferably 0.2 to 5.0 μm, still more preferably 0.5 to 1.0 μm. When the average particle diameter is less than 0.1 μm, it may not be sufficiently acted as a nucleating agent. On the other hand, when the average particle diameter exceeds 10 μm, there is a case where the resin composition becomes a cause of outgassing during foaming, which is not preferable.

In particular, the foaming nucleating agent can easily obtain a fine cell structure by easily obtaining affinity with a resin or suppressing foaming at the time of foaming due to generation of voids in the interface between the resin and the inorganic substance. In terms of surface treatment, it is preferably a surface-treated inorganic substance (especially a surface-treated hard clay).

The content of the foaming nucleating agent in the resin composition is not particularly limited, and is preferably 0.1 to 20% by weight, more preferably 0.3 to 10% by weight, based on the total amount of the resin composition (100% by weight), and further Good is 0.5~6 wt%. When the content is 0.1% by weight or more, the portion (bubble forming portion) for forming bubbles can be sufficiently ensured, and a fine cell structure can be easily obtained, which is preferable. In addition, when the content is 20% by weight or less, the viscosity of the resin composition is remarkably increased, and the outgas of the resin composition during foaming can be suppressed, and a uniform cell structure can be easily obtained, which is preferable.

Further, the above resin composition preferably contains an epoxy-modified polymer. The above epoxy-modified polymer functions as a crosslinking agent. Further, as a modifier for improving the melt tension and strain hardening degree of the resin composition (especially the resin composition containing the polyester elastomer) (Resin modifier) works. Therefore, when the resin composition contains an epoxy-modified polymer, it is preferable to obtain an instantaneous recovery rate of a specific value or more and to easily obtain excellent dustproofness. Moreover, it is easy to obtain a highly foamed and fine cell structure. Further, the epoxy-modified polymer may be used singly or in combination of two or more.

The epoxy-modified polymer is not particularly limited, and it is difficult to form a three-dimensional network structure as compared with a compound having a low molecular weight epoxy group, and a resin composition excellent in melt tension and strain hardening degree can be easily obtained (especially containing In terms of the resin composition of the polyester-based elastomer, an epoxy-modified acrylic polymer selected from a polymer having an epoxy group at the terminal or side chain of the main chain of the acrylic polymer is preferred. Or at least one polymer of an epoxy-modified polyethylene having a polymer having an epoxy group at the end of the main chain of the polyethylene or a side chain.

The weight average molecular weight of the above epoxy-modified polymer is not particularly limited, but is preferably 5,000 to 100,000, more preferably 8,000 to 80,000, still more preferably 10,000 to 70,000, still more preferably 20,000 to 60,000. Further, when the molecular weight is less than 5,000, the reactivity of the epoxy-modified polymer is increased and the high foaming cannot be performed.

The epoxy equivalent of the epoxy-modified polymer is not particularly limited, but is preferably 100 to 3000 g/eq, more preferably 200 to 2500 g/eq, still more preferably 300 to 2000 g/eq, and particularly preferably 800 to 1600 g. /eq. When the epoxy equivalent of the epoxy-modified polymer is 3,000 g/eq or less, the melt tension and the strain hardening degree of the resin composition (especially the resin composition containing the polyester elastomer) can be sufficiently increased to obtain a specific value. The above-described instantaneous recovery rate is easy to improve the dustproof property, and it is preferable to obtain a foamed structure having a high foaming and fineness. In addition, when the epoxy equivalent of the epoxy-modified polymer is 100 g/eq or more, the reactivity of the epoxy-modified polymer can be suppressed from being improved, and the viscosity of the resin composition becomes too high to allow high foaming. Bad conditions are therefore ideal.

The viscosity (B type viscosity, 25 ° C) of the above epoxy-modified polymer is not particularly limited, but is preferably from 2,000 to 4,000 mPa·s, more preferably from 2,500 to 3,200 mPa·s. If the above epoxy modification When the viscosity of the polymer is 2,000 mPa·s or more, it is preferable to suppress the breakage of the bubble wall at the time of foaming of the resin composition and to easily obtain a highly foamed and fine cell structure. On the other hand, when the viscosity is 4,000 mPa·s or less, the fluidity of the resin composition is easily obtained, and the resin composition can be effectively foamed, which is preferable.

In particular, the epoxy-modified polymer preferably has a weight average molecular weight of 5,000 to 100,000 and an epoxy equivalent of 100 to 3000 g/eq.

The content of the epoxy-modified polymer in the resin composition is not particularly limited, and is preferably 0.5 to 15.0 parts by weight, more preferably 0.6 to 10.0 parts by weight, per 100 parts by weight of the resin in the resin composition. Further, it is preferably 0.7 to 7.0 parts by weight, particularly preferably 0.8 to 3.0 parts by weight. When the content of the epoxy-modified polymer is 0.5 parts by weight or more, the melt tension and strain hardening degree of the resin composition can be increased, and a highly foamed and fine cell structure can be easily obtained, which is preferable. In addition, when the content of the epoxy-modified polymer is 15.0 parts by weight or less, it is possible to suppress the problem that the viscosity of the resin composition is too high and the high foaming cannot be performed, and it is easy to obtain a highly foamed and fine cell structure. Therefore, it is ideal.

Further, the epoxy-modified polymer can prevent the cutting of the polyester chain caused by hydrolysis (for example, hydrolysis due to moisture absorption of the raw material), pyrolysis, oxidative decomposition, etc., and can be cut. Since the broken polyester chain is re-bonded, the melt tension of the resin composition containing the polyester elastomer can be further improved. Further, in the above epoxy-modified polymer, since the epoxy group has a plurality of epoxy groups in one molecule, it is easier to form a branched structure than the conventional epoxy-based crosslinking agent, and the poly-containing polymer can be further improved. The degree of strain hardening of the resin composition of the ester elastomer.

Further, the above resin composition preferably contains a lubricant. When the resin composition contains a lubricant, the formability of the resin composition is improved, which is preferable. The slidability becomes good, and it is preferable, for example, to be easily extruded from the extruder in a desired shape without stopping. Further, the lubricants may be used singly or in combination of two or more.

The lubricant is not particularly limited, and examples thereof include aliphatic carboxylic acids and the like. A derivative (for example, an aliphatic carboxylic acid anhydride, an alkali metal salt of an aliphatic carboxylic acid, an alkaline earth metal salt of an aliphatic carboxylic acid, or the like). As the above aliphatic carboxylic acid and derivatives thereof, preferred are lauric acid and derivatives thereof, stearic acid and derivatives thereof, crotonic acid and derivatives thereof, oleic acid and derivatives thereof, maleic acid. And its derivatives, glutaric acid and its derivatives, behenic acid and its derivatives, montanic acid and its derivatives, and other fatty acid carboxylic acids having 3 to 30 carbon atoms and derivatives thereof. Further, among the fatty acid carboxylic acids having a carbon number of 3 to 30 and derivatives thereof, stearic acid and derivatives thereof are preferred from the viewpoints of the dispersibility, solubility, and surface appearance of the resin composition. , montanic acid and its derivatives, particularly preferably alkali metal salts of stearic acid, alkaline earth metal salts of stearic acid. Further, among the alkali metal salts of stearic acid and the alkaline earth metal salts of stearic acid, zinc stearate or calcium stearate is more preferred.

Further, examples of the lubricant include an acrylic lubricant. For example, an acrylic polymer external lubricant (trade name "Metablen L", manufactured by Mitsubishi Rayon Co., Ltd.) or the like can be mentioned as a commercial product of the above-mentioned acrylic lubricant.

In particular, as the lubricant, an acrylic lubricant is preferred.

The content of the lubricant in the resin composition is not particularly limited, and is preferably 0.1 to 20 parts by weight, more preferably 0.3 to 10 parts by weight, even more preferably 100 parts by weight of the resin in the resin composition. 0.5 to 8 parts by weight. When the content of the lubricant is 0.1 part by weight or more, the effect obtained by containing the lubricant is easily obtained, which is preferable. On the other hand, when the content of the lubricant is 20 parts by weight or less, it is preferable to suppress the escape of bubbles when the resin composition is foamed, thereby suppressing the inability to perform high foaming.

In the above resin composition, a crosslinking agent may be contained within a range not inhibiting the effects of the invention of the present application. The crosslinking agent is not particularly limited, and examples thereof include an epoxy crosslinking agent, an isocyanate crosslinking agent, a stanol alcohol crosslinking agent, a melamine resin crosslinking agent, a metal salt crosslinking agent, and a metal chelate. Compound crosslinking agent, amine resin crosslinking agent Wait. Further, the crosslinking agent may be used singly or in combination of two or more.

Further, the resin composition may contain a crystallization accelerator insofar as the effects of the invention of the present application are not inhibited. The crystallization accelerator is not particularly limited, and examples thereof include an olefin resin. As such an olefin-based resin, a resin having a broad molecular weight distribution and a shoulder-type type on a high molecular weight side, a resin of a micro-crosslinking type (a resin in which a plurality of types are cross-linked), a resin having a long-chain branch type, and the like are preferable. . Examples of the olefin-based resin include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, polypropylene, a copolymer of ethylene and propylene, ethylene or propylene, and other α-olefins (for example). a copolymer of butene-1, pentene-1, hexene-1, 4-methylpentene-1, etc., ethylene and other ethylenically unsaturated monomers (for example, vinyl acetate, acrylic acid, acrylate) a copolymer of methacrylic acid, methacrylic acid ester, vinyl alcohol, etc.). Further, when the olefin resin is a copolymer, it may be a copolymer of any of a random copolymer and a block copolymer. Further, the olefin resin may be used singly or in combination of two or more kinds.

Further, the resin composition may contain a flame retardant within a range that does not inhibit the effects of the invention of the present application. The reason for this is that the resin foaming system of the present invention contains a resin and therefore has a property of being easily burned, but may be used for applications in which it is necessary to impart flame retardancy to an electric machine or an electronic device. The flame retardant is not particularly limited, and examples thereof include powder particles having flame retardancy (for example, various flame retardants in a powder form), and an inorganic flame retardant is preferably used. The inorganic flame retardant may be, for example, a bromine-based flame retardant, a chlorine-based flame retardant, a phosphorus-based flame retardant, or an antimony-based flame retardant, but a chlorine-based flame retardant or a bromine-based flame retardant is burned. When a gas component which is harmful to the human body and corrosive to the machine is generated, and the phosphorus-based flame retardant or the antimony-based flame retardant has problems such as harmfulness or explosiveness, it is preferably a halogen-free and non-antimony-based inorganic resistor. Burning agent (inorganic flame retardant that does not contain halogen compounds and antimony compounds). Examples of the halogen-free and antimony-based inorganic flame retardant include hydrated metals such as aluminum hydroxide, magnesium hydroxide, magnesium oxide, nickel oxide hydrate, and magnesium oxide and zinc oxide hydrate. Compounds, etc. Furthermore, the hydrated metal oxide can also be surface treated. These flame retardants may be used singly or in combination of two or more.

Further, in the above resin composition, the following additives may be contained as needed within the range which does not inhibit the effects of the present invention. Examples of such an additive include a crystal nucleating agent, a plasticizer, a coloring agent (carbon black for coloring, a pigment, a dye, etc.), an ultraviolet absorber, an antioxidant, an anti-aging agent, a reinforcing agent, and an antistatic agent. Agent, surfactant, tension modifier, anti-shrinkage agent, fluidity modifier, vulcanizing agent, surface treatment agent, dispersing aid, modifier for polyester resin, and the like. Further, the additives may be used singly or in combination of two or more.

In particular, the resin composition has an instantaneous recovery rate of a specific value or more, a repulsive force at a compression of 50% in a specific range, an average cell diameter within a specific range, a maximum cell diameter of a specific value or less, and flexibility. It is preferable to contain at least the following (i)-(iv) in terms of the ease of obtaining the resin foam excellent in dustproof property.

(i): a polyester-based elastomer having a melt flow rate (MFR) of from 1.5 to 4.0 g/10 min at 230 ° C (preferably a melt flow rate (MFR) of from 1.5 to 4.0 g/10 min at 230 ° C, Further, as the polyester elastomer of the block copolymer of the hard segment and the soft segment, it is more preferable that the melt flow rate (MFR) at 230 ° C is 1.5 to 4.0 g/10 min, and the aromatic dicarboxylic acid and A polyester formed by polycondensation of a diol component having a carbon number of 2 to 4 in a main chain between a hydroxyl group and a hydroxyl group is a hard segment and a polyether is a soft segment. Copolymer)

(ii): epoxy modified polymer

(iii): lubricant (preferably acrylic lubricant)

(iv): foaming nucleating agent (preferably surface treated inorganic matter, more preferably surface treated hard clay)

The method for producing the resin composition is not particularly limited, and examples thereof include a treatment in which the above-mentioned resin, an additive to be added, and the like are mixed. Furthermore, heat can also be applied during production.

The melt tension (pull speed: 2.0 m/min) of the above resin composition is not particularly limited, but is preferably 15 to 70 cN, more preferably 13 to 60 cN, still more preferably 15 to 55 cN, and particularly preferably 26 to 50 cN. . When the melt tension of the resin composition is less than 10 cN, when the resin composition is foamed, the expansion ratio is low, and it is difficult to form independent bubbles, and the shape of the formed bubbles is less likely to be uniform. On the other hand, when the melt tension of the resin composition exceeds 70 cN, the fluidity is lowered to adversely affect the foaming.

In addition, the term "melt tension" means a tension when a molten resin extruded at a predetermined temperature and an extrusion speed is drawn into a rope at a predetermined drawing speed from a predetermined die using a predetermined apparatus. In the present invention, a Capillary Extrusion Rheometer manufactured by Malvern Co., Ltd. was used, and a resin having a diameter of 2 mm and a length of 20 mm was used to extrude the resin at a fixed speed of 8.8 mm/min at 2 m/min. The pull rate of the pull speed is set to the melt tension.

Further, the melt tension was measured from the melting point of the resin of the resin composition to a temperature of 10 ± 2 ° C on the high temperature side. This is because the resin does not become in a molten state at a temperature that does not reach the melting point, and on the other hand, it completely becomes a fluid at a temperature that greatly exceeds the melting point to the high temperature side, so that the melt tension cannot be measured.

The strain hardening degree (strain rate: 0.1 [1/s]) of the above resin composition is not particularly limited, but a uniform and dense cell structure is obtained, and foaming of cells at the time of foaming is suppressed to obtain high foaming. In terms of the foam, it is preferably from 2.0 to 5.0, more preferably from 2.5 to 4.5. Further, the strain hardening degree of the resin composition is a strain hardening degree at a melting point of the resin of the resin composition. Further, the strain hardening degree is a region in which the uniaxial elongation viscosity gradually rises (linear region) with an increase in strain after the start of the measurement, and the uniaxial elongation viscosity is over the region (non- In the linear region), an index indicating the degree of increase in the uniaxial elongation viscosity.

The resin foam of the present invention is preferably obtained by foaming the above resin composition into Formed in shape. The foaming method of the above resin composition is not particularly limited, and a foaming method in which a high-pressure inert gas is impregnated into the resin composition and then subjected to reduced pressure (release pressure) is preferred. That is, the resin foam of the present invention is preferably formed by a step of impregnating the resin composition with a high-pressure inert gas and then reducing the pressure. Further, the above-mentioned inert gas means a gas which is inert to the resin composition and which can be impregnated.

Further, examples of the foaming method of the resin composition include a physical foaming method (a foaming method using a physical method) or a chemical foaming method (a foaming method using a chemical method). Concerned about the environmental impact of the flammability or toxicity of the material used as a foaming agent (foaming agent gas) and the destruction of the ozone layer in the physical foaming method, but the foaming method using an inert gas does not use such a hair. The method of the environment is considered in terms of the foaming agent. In the chemical foaming method, since the residue of the foaming gas generated by the foaming agent remains in the foam, there is a corrosive gas or gas especially when applied to an electronic device having a high degree of low pollution. The pollution caused by the impurities in the problem becomes a problem. However, according to the foaming method using an inert gas, a clean foam in which such impurities or the like are not present can be obtained. Further, in any of the physical foaming method and the chemical foaming method, it is considered that it is difficult to form a fine cell structure, and in particular, it is extremely difficult to form fine bubbles of 300 μm or less.

The inert gas is not particularly limited, and examples thereof include carbon dioxide gas (carbonic acid gas), nitrogen gas, helium gas, and air. These gases can also be used in combination. Among them, carbon dioxide gas is preferred in terms of a large amount of impregnation and a high impregnation speed.

Further, in terms of speeding up the impregnation speed to the resin composition, the inert gas is preferably in a supercritical state. In the supercritical state, the solubility of the gas to the resin composition is increased, and high concentration of the mixture can be achieved. Further, when the pressure after impregnation is drastically lowered, as described above, it can be impregnated at a high concentration, so that the generation of bubble nuclei is increased, and even if the porosity is the same, the density of bubbles formed by the growth of the nuclei will increase, so that fineness can be obtained. Bubbles. Further, the critical temperature of carbon dioxide is 31 ° C and the critical pressure is 7.4 MPa.

As described above, the resin foam of the present invention is preferably produced by impregnating a resin composition with a high-pressure inert gas. However, in this case, it is also possible to use an appropriate shape in which the resin composition is formed into a sheet shape in advance. After the unfoamed resin molded body (unfoamed molded product) is formed, a high-pressure inert gas is impregnated into the unfoamed resin molded body, and the pressure is released to thereby form a batch method of foaming, and may be used. The resin composition is kneaded under pressure with a high-pressure inert gas, and the pressure is released while forming, and a continuous manner of forming and foaming is performed.

The case where the resin foam of the present invention is produced in a batch manner will be described. In the batch method, first, an unfoamed resin molded body is produced when the resin foam is produced, and the method for producing the unfoamed resin molded body is not particularly limited, and for example, the resin composition is uniaxially extruded. A method of forming an extruder such as a machine or a twin-screw extruder; and kneading the resin composition in advance using a kneading machine equipped with a blade such as a roller, a cam, a kneading machine, or a Banbury type, and using heat A method of press molding into a specific thickness by a press machine of a plate, a method of forming a resin composition by using an injection molding machine, or the like. Among these methods, an appropriate method is preferably selected in such a manner as to obtain an unexpanded resin molded body of a desired shape or thickness. Further, the unfoamed resin molding system may be produced by other molding methods in addition to extrusion molding, press molding, and injection molding. Moreover, the shape of the unfoamed resin molded body is not limited to a sheet shape, and various shapes can be selected depending on the application. For example, a sheet shape, a roll shape, a corner column shape, a plate shape, etc. are mentioned. Next, bubbles are formed by placing the above-mentioned unfoamed resin molded body (molded body formed of the resin composition) into a pressure resistant container (high pressure container), injecting (introducing) a high pressure inert gas, and making a high pressure The gas impregnation step of impregnating the inert gas with the unfoamed resin molded body; releasing the pressure (usually at atmospheric pressure) at a time when the high-pressure inert gas is sufficiently impregnated, and decompressing the bubble core in the unfoamed resin molded body Step; heating step of growing the bubble nuclei by heating according to the situation (if necessary). Further, the bubble nucleus may be grown at room temperature without providing a heating step. After the bubble is grown as described above, it is rapidly cooled by cold water or the like as needed, and the shape is fixed. A resin foam can be obtained. Further, the introduction of the high-pressure inert gas may be carried out continuously or discontinuously. Further, as a heating method for growing the bubble nucleus, a known or conventional method such as a water bath, an oil bath, a hot roll, a hot air oven, far infrared ray, near infrared ray, or microwave may be employed.

In other words, the resin foam of the present invention can be formed by foaming by subjecting an inert gas containing a high pressure to an unfoamed molded article containing the above resin composition and then performing a pressure reduction step. Further, it may be formed by further heating a high-pressure inert gas by impregnating the unfoamed molded article containing the resin composition, followed by depressurization.

On the other hand, in the case of being produced in a continuous manner, for example, a case where the resin composition is kneaded by using an extruder such as a single-axis extruder or a twin-screw extruder while being injected is used. (introducing) a high-pressure inert gas, a kneading impregnation step in which the inert gas is sufficiently impregnated in the resin composition; extruding the resin composition through a die or the like provided at the front end of the extruder, thereby releasing the pressure (usually, atmospheric pressure) Up to this, the molding and decompression steps of molding and foaming are simultaneously performed. Further, depending on the case (if necessary), a heating step of growing the bubbles by heating may be provided. After the bubble is grown in this manner, it is rapidly cooled by cold water or the like as needed, and the shape is fixed, whereby a resin foam can be obtained. Further, in the kneading impregnation step and the molding decompression step, an injection molding machine or the like may be used in addition to the extruder.

That is, the resin foam of the present invention can be formed by foaming by subjecting a high-pressure inert gas to a molten resin composition and then performing a pressure reduction step. Moreover, the resin foam of the present invention can be formed by further heating by subjecting a high-pressure inert gas to a molten resin composition, followed by depressurization.

In the gas impregnation step in the above-described batch mode or the kneading impregnation step in the above-described continuous mode, the mixing amount of the inert gas is not particularly limited, and is, for example, preferably 1 to 10% by weight based on the total amount of the resin composition. Good is 2~8 wt%.

The gas impregnation step in the above batch mode or the kneading in the above continuous mode In the dip step, the pressure at which the inert gas is impregnated into the unfoamed resin molded body or the resin composition is preferably 3 MPa or more (for example, 3 to 100 MPa), more preferably 4 MPa or more (for example, 4 to 100 MPa). When the gas pressure is less than 3 MPa, the bubble growth at the time of foaming is remarkable, and the bubble diameter becomes excessively large, and for example, a problem such as a decrease in dustproof effect is likely to occur, which is not preferable. The reason is that if the pressure is low, the amount of gas impregnation is relatively small compared to the case of high pressure, and the bubble nucleation rate decreases and the number of bubble nuclei formed decreases, so that the amount of gas per bubble increases instead of bubbles. The path is extremely increased. Further, in the pressure region of less than 3 MPa, the bubble diameter and the bubble density can be largely changed by merely changing the impregnation pressure a little, so that it is difficult to control the bubble diameter and the bubble density.

Further, in the gas impregnation step in the batch mode or the kneading impregnation step in the continuous mode, the temperature at which the high-pressure inert gas is impregnated into the unfoamed resin molded body or the polyester-based elastomer composition can be widely used. The internal selection is preferably 10 to 350 ° C in consideration of the operability or the like. For example, in the batch mode, the impregnation temperature in the case where the high-pressure inert gas is impregnated into the sheet-shaped unfoamed resin molded body is preferably 40 to 300 ° C, more preferably 100 to 250 ° C. Further, in the continuous mode, the temperature at which the high-pressure inert gas is injected into the resin composition and kneaded is preferably 150 to 300 ° C, more preferably 210 to 250 ° C. Further, in the case of using carbon dioxide as a high-pressure gas, in order to maintain the supercritical state, the temperature (impregnation temperature) at the time of impregnation is preferably 32 ° C or more (especially 40 ° C or more).

Further, in the pressure reduction step, the pressure reduction rate is not particularly limited, and is preferably 5 to 300 MPa/s in order to obtain uniform fine bubbles. Further, the heating temperature in the heating step is not particularly limited, but is preferably 40 to 250 ° C, more preferably 60 to 250 ° C.

Moreover, according to the method for producing a resin foam described above, a resin foam having a high expansion ratio can be produced, and thus a thick resin foam can be obtained. For example, in the case of manufacturing the resin foam by the above-described continuous method, in order to maintain the pressure inside the extruder in the kneading impregnation step, it is necessary to minimize the distance between the die mounted on the front end of the extruder (usually 0.1 to 1.0). Mm). Therefore, in order to obtain a thick resin foam, it is necessary to pass through a narrow pitch. The extruded resin composition is foamed at a higher magnification, but a higher expansion ratio has not previously been obtained, and thus the thickness of the formed foam is limited to a relatively thin one (for example, 0.5 to 2.0 mm). On the other hand, according to the method for producing the resin foam produced by using a high-pressure inert gas, a resin foam having a final thickness of 0.30 to 5.00 mm can be continuously obtained.

In the resin foam of the present invention, since the repulsive force at a compression of 50% is within a specific range, the average cell diameter is within a specific range, and the maximum cell diameter is below a specific value, a uniform and fine cell structure is obtained. Excellent in softness. Therefore, it is possible to follow a small gap.

Further, in the resin foam of the present invention, the instantaneous recovery rate is a specific value or more, the average cell diameter is within a specific range, and the maximum cell diameter is equal to or less than a specific value, so that the dustproof property is excellent. Further, since the coarse cells are not contained, there is no problem that dust enters from the coarse cells and the dustproof property is lowered.

Furthermore, since the resin foam of the present invention has a fine and uniform cell structure and the instantaneous recovery rate is a specific value or more, it is difficult to generate a bubble when the foam (foam) is cut and punched. The rupture of the pore structure. Therefore, the workability is excellent.

Since the resin foaming system of the present invention has the above characteristics, it can be preferably used as a sealing material or a dustproof material for an electric machine or an electronic device. Moreover, it can be preferably used as a cushioning material or a shock absorbing material, and in particular, it can be preferably used as a cushioning material or a shock absorbing material for an electric machine or an electronic machine.

(foaming member)

The resin foaming system of the present invention can also be used as a foaming member. That is, the foaming member is a member including the above-described resin foam of the present invention. The foam member may be, for example, a structure including only the foam of the present invention, or another layer (particularly an adhesive layer (adhesive layer), a substrate layer, or the like) laminated on the resin foam. Composition.

The shape of the foam member is not particularly limited, but is preferably a sheet shape (including a film shape) or a belt shape. Further, the foaming member may be processed in such a manner as to have a desired shape or thickness. For example, it can be implemented in accordance with the device or machine, housing, components, etc. used. Processed into a variety of shapes.

In particular, the foamed member preferably has an adhesive layer. For example, in the case where the foam member is a sheet-like foam member, it is preferred to have an adhesive layer on one or both sides thereof. When the foam member has an adhesive layer, for example, a processing sheet can be provided on the foam member by interposing an adhesive layer, and further, it can be fixed or temporarily fixed to the adherend (for example, a casing or a member).

The adhesive for forming the above-mentioned adhesive layer is not particularly limited, and examples thereof include an acrylic adhesive, a rubber adhesive (a natural rubber adhesive, a synthetic rubber adhesive, etc.), a polyoxygen adhesive, and a poly An ester-based adhesive, a urethane-based adhesive, a polyamide-based adhesive, an epoxy-based adhesive, a vinyl alkyl ether-based adhesive, a fluorine-based adhesive, or the like. The adhesive system may be used alone or in combination of two or more. Further, the adhesive may be an adhesive of any form such as a latex adhesive, a solvent adhesive, a hot melt adhesive, an oligomer adhesive, or a solid adhesive. In particular, the adhesive is preferably an acrylic adhesive from the viewpoint of preventing contamination of the adherend. In other words, the foam member preferably has an acrylic pressure-sensitive adhesive layer on the resin foam of the present invention.

The thickness of the above adhesive layer is not particularly limited, but is preferably 2 to 100 μm, more preferably 10 to 100 μm. The thinner the adhesive layer layer is, the higher the effect of preventing the adhesion of dust or dust at the ends, and the thinner the thickness, the better. Further, the adhesive layer may have any one of a single layer and a laminate.

In the above foamed member, the above adhesive layer may be provided via another layer (lower layer). Examples of such a lower layer include other adhesive layers, intermediate layers, undercoat layers, and base material layers (especially, a film layer or a nonwoven fabric layer). Further, the adhesive layer may be protected by a release film (separator) (for example, a release paper, a release film, or the like).

Since the foaming member includes the above-described resin foam of the present invention, it is excellent in dustproofness and excellent in flexibility. Moreover, it has flexibility to follow a small gap. Further, workability Also excellent.

The above-mentioned foamed member has the characteristics as described above, and therefore can be preferably used as a member used when a plurality of members or parts are attached (mounted) to a specific portion. In particular, the foaming member is used in an electric or electronic device, and can be preferably used as a member used when a component constituting an electric or electronic device is attached (mounted) to a specific portion.

That is, the above foaming member can be preferably used as an electric or electronic machine. That is, the foam member may be a foam member for electric or electronic equipment.

The various members or components that can be attached (mounted) by the above-described foaming member are not particularly limited, and for example, various members or parts of electric or electronic equipment can be preferably used. Examples of the member or the component for the electric or electronic device include an image display member (display portion) mounted on an image display device such as a liquid crystal display, an electroluminescence display, or a plasma display (in particular, a small figure). For example, a display member or an optical member or an optical component such as a camera or a lens (especially, a small camera or lens) mounted on a device for communicating with a mobile device such as a "mobile phone" or a "mobile information terminal".

The preferred embodiment of the foam member of the present invention is used for the purpose of dustproof, light-shielding, buffering, etc., and is used around a display portion such as an LCD (liquid crystal display) or clamped to an LCD ( A case where the display unit and the casing (window portion) are used in a liquid crystal display or the like.

[Examples]

Hereinafter, the present invention will be more specifically described by way of examples and comparative examples. The invention is not limited by these.

(Example 1)

A block copolymer of polybutylene terephthalate as a hard segment and a polyether as a soft segment (trade name "Pelprene P-90BD", manufactured by Toyobo Co., Ltd., melt flow rate at 230 ° C: 3.0 g/10 min, melting point: 204 ° C): 100 parts by weight, an acrylic lubricant (trade name "Metablen L-1000", manufactured by Mitsubishi Rayon Co., Ltd. Manufactured: 5 parts by weight of hard clay surface-treated with a decane coupling agent (trade name "ST-301", manufactured by Shiraishi Calcium Co., Ltd.): 1 part by weight, carbon black (trade name "旭#35", Asahi Carbon Co., Ltd.): 5 parts by weight and an epoxy-based modifier (epoxy-modified acrylic polymer, weight average molecular weight (Mw): 50,000, epoxy equivalent: 1200 g/eq, viscosity: 2850 mPa‧s 2 parts by weight, after kneading at a temperature of 220 ° C by a biaxial kneading machine, it was extruded into a rope shape, and after water cooling, it was cut into pellets and formed.

The pellet was placed in a single-screw extruder, and carbon dioxide gas was injected at a pressure of 17 (13 MPa after injection) in an environment of 240 °C. After the carbon dioxide gas was sufficiently saturated, it was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a sheet-shaped polyester elastomer foam having a thickness of 2.0 mm.

(Example 2)

A block copolymer of polybutylene terephthalate as a hard segment and a polyether as a soft segment (trade name "Pelprene P-90BD", manufactured by Toyobo Co., Ltd., melt flow rate at 230 ° C: 3.0 g/10 min, melting point: 204 ° C): 100 parts by weight, an acrylic lubricant (trade name "Metablen L-1000", manufactured by Mitsubishi Rayon Co., Ltd.): 1 part by weight, surface treatment with a decane coupling agent Hard clay (trade name "ST-301", manufactured by Shiraishi Calcium Co., Ltd.): 1 part by weight, carbon black (trade name "旭#35", manufactured by Asahi Carbon Co., Ltd.): 5 parts by weight and epoxy Modifier (epoxy modified acrylic polymer, weight average molecular weight (Mw): 50000, epoxy equivalent: 1200 g/eq, viscosity: 2850 mPa‧s): 2 parts by weight, using a biaxial kneading machine at 220 ° C After kneading at a temperature, it is extruded into a rope shape, and after water cooling, it is cut into pellets and formed.

The pellet was placed in a single-screw extruder, and carbon dioxide gas was injected at a pressure of 17 (13 MPa after injection) in an environment of 240 °C. After the carbon dioxide gas is sufficiently saturated, it is cooled to a temperature suitable for foaming, and then extruded from a die to obtain a thickness of 2.0 mm. A sheet-like polyester elastomer foam.

(Example 3)

A block copolymer of polybutylene terephthalate as a hard segment and a polyether as a soft segment (trade name "Pelprene P-90BD", manufactured by Toyobo Co., Ltd., melt flow rate at 230 ° C: 3.0 g/10 min, melting point: 204 ° C): 100 parts by weight, polyacetal (trade name "M25-44", manufactured by Polyplastics Co., Ltd., melt flow rate at 230 ° C: 3.0 g/10 min): 10 parts by weight, Acrylic lubricant (trade name "Metablen L-1000", manufactured by Mitsubishi Rayon Co., Ltd.): 5 parts by weight of hard clay surface-treated with a decane coupling agent (trade name "ST-301", white stone calcium Co., Ltd.): 1 part by weight, carbon black (trade name "旭#35", manufactured by Asahi Carbon Co., Ltd.): 5 parts by weight and epoxy-based modifier (epoxy-modified acrylic polymer, weight average) Molecular weight (Mw): 50000, epoxy equivalent: 1200 g/eq, viscosity: 2850 mPa s): 2 parts by weight, after mixing at 220 ° C using a biaxial kneading machine, extruding into a rope, after water cooling It is cut into pellets to form.

The pellet was placed in a single-screw extruder, and carbon dioxide gas was injected at a pressure of 17 (13 MPa after injection) in an environment of 240 °C. After the carbon dioxide gas was sufficiently saturated, it was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a sheet-shaped polyester elastomer foam having a thickness of 2.0 mm.

(Example 4)

A block copolymer of polybutylene terephthalate as a hard segment and a polyether as a soft segment (trade name "Pelprene P-90BD", manufactured by Toyobo Co., Ltd., melt flow rate at 230 ° C: 3.0 g/10 min, melting point: 204 ° C): 100 parts by weight, an acrylic lubricant (trade name "Metablen L-1000", manufactured by Mitsubishi Rayon Co., Ltd.): 5 parts by weight, surface treatment with a decane coupling agent Hard clay (trade name "ST-301", manufactured by Shiraishi Calcium Co., Ltd.): 3 parts by weight, carbon black (trade name "旭#35", manufactured by Asahi Carbon Co., Ltd.): 5 parts by weight and epoxy Modifier (ring Oxygen-modified acrylic polymer, weight average molecular weight (Mw): 50,000, epoxy equivalent: 1200 g/eq, viscosity: 2850 mPa s): 2 parts by weight, kneaded at 220 ° C using a biaxial kneading machine Thereafter, it was extruded into a rope shape, and after water cooling, it was cut into pellets and formed. The pellet was placed in a single-screw extruder, and carbon dioxide gas was injected at a pressure of 17 (13 MPa after injection) in an environment of 240 °C. After the carbon dioxide gas was sufficiently saturated, it was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a sheet-shaped polyester elastomer foam having a thickness of 1.5 mm.

(Comparative Example 1)

A block copolymer of polybutylene terephthalate as a hard segment and a polyether as a soft segment (trade name "Hytrel 5577", manufactured by Du Pont Toray Co., Ltd., 230 ° C Melt flow rate: 1.8 g/10 min, melting point: 208 ° C): 100 parts by weight, acrylic lubricant (trade name "Metablen L-1000", manufactured by Mitsubishi Rayon Co., Ltd.): 5 parts by weight, polypropylene ( Product name "NEWSTREN SH9000", manufactured by Japan Polypropylene Co., Ltd.): 1 part by weight, magnesium hydroxide (average particle diameter: 0.7 μm): 1 part by weight, carbon black (trade name "旭#35" , manufactured by Asahi Carbon Co., Ltd.): 5 parts by weight and an epoxy-based crosslinking agent (trifunctional epoxy compound, trade name "TEPIC-G", manufactured by Nissan Chemical Industries, Ltd.): 0.5 part by weight, using a double shaft The kneading machine was kneaded at a temperature of 220 ° C, and then extruded into a rope shape, and after water cooling, it was cut into pellets and formed.

The pellet was placed in a single-screw extruder, and carbon dioxide gas was injected at a pressure of 17 (13 MPa after injection) in an environment of 240 °C. After the carbon dioxide gas was sufficiently saturated, it was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a sheet-shaped polyester elastomer foam having a thickness of 2.2 mm.

(Comparative Example 2)

Polypropylene (melt flow rate (MFR): 0.35 g/10 min): 45 parts by weight, polyolefin-based elastomer (melt flow rate (MFR): 6 g/10 min): 55 parts by weight, polyethylene Alkene: 10 parts by weight, nucleating agent (magnesium hydroxide, average particle diameter: 0.7 μm): 10 parts by weight and carbon black (trade name "Asahi #35", manufactured by Asahi Carbon Co., Ltd.): 5 parts by weight, using The biaxial kneading machine was kneaded at a temperature of 200 ° C, and then extruded into a rope shape, and after water cooling, it was cut into pellets to obtain a particulate matter.

This pellet was placed in a single-shaft extruder manufactured by Nippon Steel Co., Ltd., and carbon dioxide gas was injected at a pressure of 13 (12 MPa after injection) in an environment of 220 °C. The carbon dioxide gas system was injected at a ratio of 5% by weight relative to the total amount of the particulate matter. After the carbon dioxide gas was sufficiently saturated, it was cooled to a temperature suitable for foaming, and then extruded from a die to obtain a sheet-like resin foam having a thickness of 2.3 mm.

(Comparative Example 3)

A commercially available polyurethane having an average cell diameter of 160 μm, a compression of 50%, a rebound stress (50% anti-repulsion load) of 0.7 N/cm ² and an apparent density of 0.15 g/cm ³ was used. A foam of ingredients.

The foaming system was in the form of a sheet having a thickness of 1.0 mm.

(Evaluation)

The foams of the examples and the comparative examples were subjected to the following measurement or evaluation. Then, the results are shown in Table 1.

(visual density)

The foam was punched out by a punching die having a width of 20 mm and a length of 20 mm, and was set as a sheet-like test piece. The size of the test piece was measured using a vernier caliper. Also, using the diameter of the measuring terminal ( The thickness of the test piece was measured for a 1/100 dial gauge of 20 mm. The volume of the test piece was calculated from the equivalent values. Next, the weight of the test piece was measured using an electronic balance. The apparent density (g/cm ³ ) of the foam was calculated by the following formula based on the volume of the test piece and the weight of the test piece.

The apparent density of the foam (g/cm ³ ) = (weight of the test piece) / (volume of the test piece)

(Rebound force when compressing 50% (repulsive load at 50% compression, 50% load compression))

The measurement was carried out in accordance with the compression hardness measurement method disclosed in JIS K 6767.

The foam was cut into a test piece having a width of 30 mm × length: 30 mm. Then, the test piece was compressed at a compression speed of 10 mm/min in the thickness direction until the compressibility (N) was converted to a unit area (1 cm ² ) to obtain a repulsive force (N). /cm ² ).

(instantaneous recovery rate)

The foam was compressed in the thickness direction at 23 ° C using an electromagnetic force micro-tester (Micro Servo) (trade name "MMT-250", manufactured by Shimadzu Corporation) until the thickness became the initial thickness. 20%, maintain compression for 1 minute. In the 23 ° C environment, the compression state was released, and the recovery behavior (thickness change, thickness recovery) of the thickness of the foam was taken by a high speed camera (High Speed Camera), and 0.6 from the uncompressed state was obtained from the image taken. The thickness of the foam after the second. Then, the instantaneous recovery rate was obtained by the following formula.

Instant recovery rate (%) = (thickness 0.6 seconds after decompression) / (initial thickness) × 100

(average cell diameter, maximum cell diameter)

A magnifying microscope (trade name "VHX-500", manufactured by KEYENCE Co., Ltd.) was used to obtain an enlarged image of the bubble portion of the foam, and image analysis was performed using the analysis software of the measuring device. The cell diameter (μm) of the cells was determined, and the average cell diameter (μm) and the maximum cell diameter (μm) were determined. The number of bubbles of the enlarged image obtained is about 200. Further, the cell diameter is obtained by calculating the area of the cell and converting the diameter of the approximate circle.

(dustproof)

The measurement of the dustproofness of the foam is carried out in accordance with the method for evaluating the dynamic dustproof property in Japanese Patent Laid-Open Publication No. 2011-162717. The dust resistance was measured in the case where the compression ratio of the foam was 50%.

Specifically, the measurement was carried out as follows. The foam was punched out into a frame shape (window frame shape) (width: 1 mm) as shown in Fig. 1 to prepare a sample for measurement.

The sample for measurement was attached to the evaluation container (see FIGS. 2 and 3) so as to be compressed in the thickness direction until the thickness became 50% of the initial thickness (in a state of 50% compression). As shown in Fig. 2, the sample for measurement was placed between the foam compression plate and the black acrylic plate fixed to the aluminum plate of the base plate. In the evaluation container in which the sample for measurement is mounted, it is a system in which a certain area of the inside is closed by the sample for measurement. After the measurement sample was attached to the evaluation container, 0.1 g of corn starch (particle diameter: 17 μm) as dust was placed in the powder supply unit, and the evaluation container was placed in a drum type drop tester (rotary type drop device) to Rotate at a speed of 1 rpm.

Then, the number of particles (dust, corn starch) that has entered the inside of the evaluation container from the powder supply unit through the sample for measurement is measured after the specific number of times of the target collision is obtained. The number of particles that invaded into the inside of the evaluation container was determined by observing a black acrylic plate attached to an aluminum plate and particles of a black acrylic plate as a cover, and observing the black acrylic plate on the aluminum plate side. The black acrylic plate on the side of the tie plate and the cover side was used to create a still image, and the image analysis software was used to perform binarization processing, and the number of each particle was determined, and these were totaled. Furthermore, the observation is carried out in a cleaning station in order to reduce the influence of floating dust in the air.

(melt tension)

For the measurement of the melt tension, a resin extruded at a fixed speed of 8.8 mm/min was pulled at a pulling speed of 2 m/min using a Capillary Extrusion Rheometer manufactured by Malvern Co., Ltd. from a capillary having a diameter of 2 mm and a length of 20 mm. The tension is set to the melt tension.

Further, at the time of measurement, the particulate matter before foam molding was used. Further, the temperature at the time of measurement was a temperature of 10 ± 2 ° C from the melting point of the resin to the high temperature side.

(strain hardening degree)

At the time of measurement, the particulate matter before foam molding was used. The pellet was formed into a sheet having a thickness of 1 mm using a heated hot plate press to obtain a sheet, and a sample was cut from the sheet (vertical: 10 mm, transverse: 10 mm, thickness: 1 mm).

From the above samples, a uniaxial elongation viscosity at a strain rate of 0.1 [1/s] was measured using a uniaxial elongation viscometer (manufactured by TA Instruments). Then, the strain hardening degree was obtained according to the following formula.

Strain hardening degree = log η max / log η 0.2

(ηmax represents the elongational viscosity at the highest uniaxial elongational viscosity, and η0.2 represents the elongational viscosity when the strain ε is 0.2).

Further, the temperature at the time of measurement was made the melting point of the resin.

[Industrial availability]

The resin foam and the foamed member of the present invention have excellent dustproof properties and excellent flexibility, and thus can be preferably used as an electric or electronic machine.

Claims (14)

A resin foam characterized in that the instantaneous recovery rate as defined below is 50% or more, the rebound force at a compression of 50% is 0.1 to 4.0 N/cm ² , and the average cell diameter is 10 to 150 μm, and the maximum bubble is obtained. The hole diameter is 300 μm or less, and the instantaneous recovery rate is: in the case of a sheet-like resin foam, it is compressed in the thickness direction for 1 minute so as to have a thickness of 20% of the initial thickness in an environment of 23 ° C, and then released in a 23 ° C environment. The compression state, the ratio of the thickness to the initial thickness after 0.6 seconds from the release of the compression state. The resin foam of claim 1, wherein the apparent density is from 0.01 to 0.20 g/cm ³ . The resin foam of claim 1 or 2, wherein the resin constituting the resin foam is a thermoplastic resin. The resin foam of claim 3, wherein the thermoplastic resin is a polyester. The resin foam according to any one of claims 1 to 4, wherein the resin foaming system is formed by a step of depressurizing a high-pressure inert gas after impregnating the resin composition. The resin foam according to claim 5, which is formed by impregnating an unexpanded molded article containing the above-mentioned resin composition with a high-pressure inert gas and then decompressing it. The resin foam of claim 5 is formed by foaming a high pressure inert gas by impregnating the molten resin composition and then depressurizing. The resin foam according to any one of claims 5 to 7, which is formed by a step of subjecting a high-pressure inert gas to a reduced pressure and further heating. The resin foam according to any one of claims 5 to 8, wherein the inert gas is carbon dioxide gas. The resin foam according to any one of claims 5 to 9, wherein the high-pressure inert gas is in a supercritical state. A foamed member comprising the resin foam according to any one of claims 1 to 10. The foam member according to claim 11, wherein the adhesive layer is contained on the resin foam. The foam member according to claim 12, wherein the adhesive layer is formed on the resin foam by a separator layer. The foam member of claim 12 or 13, wherein the adhesive layer is an acrylic adhesive layer.