Resin-foam composite article

Abstract

Provided is a resin-foam composite article comprising a foam layer and a surface layer provided on at least one surface of the foam layer, wherein the surface layer contains inorganic particles. In a section of the surface layer which is parallel to the thickness direction and TD direction of the resin-foam composite article, the average proportion of sections of the inorganic particles, as determined with an X-ray CT analyzer, is 30% or less.

Description

Resin foam composite products

[0001] The present invention relates to a resin foam composite article.

[0002] Conventionally, foam sheets have been widely used in various fields because they can be easily manufactured into products with shapes suited to specific purposes using various molding methods, such as vacuum forming. In particular, in automotive applications, they are used as interior materials for ceilings, doors, instrument panels, etc., to enhance design, feel, and a sense of luxury. Examples of interior materials used in automobiles include cross-linked olefin resin foam sheets. However, cross-linked polyolefin resin foams often emit odors due to decomposition products of polyolefin resins, which users find unpleasant. Known techniques for reducing the odor of foams include a method of incorporating a deodorizing agent, such as activated carbon, into the foam (Patent Document 1) and a method of incorporating an odor suppressant, such as carbon black, into the foam (Patent Document 2).

[0003] JP-A No. 11-60774 JP-A No. 11-263863

[0004] However, since such foam sheets are often wound into roll products, they are required to have sufficient performance to prevent wrinkles from occurring during winding and unwinding. Furthermore, when the foam sheet is made into a roll product, as described above, if a deodorant or an odor suppressant is added to the foam, the surface smoothness of the foam is impaired or the foam becomes hard, resulting in problems such as poor handling and usability.

[0005] Therefore, an object of the present invention is to provide a resin foam composite product that can suppress odor generation, can prevent wrinkles from occurring during winding and unwinding, and has excellent handleability.

[0006] As a result of extensive investigation, the present inventors have found that the above-mentioned problems can be solved by providing a surface layer containing inorganic particles on at least one surface of a foam, and then setting the average ratio of cross sections of the inorganic particles in cross sections of the surface layer in a certain direction to a predetermined value or less. That is, the present invention provides the following [1] to [6].

[0007] [1] A resin foam composite comprising a foam layer and a surface layer portion provided on at least one surface of the foam layer, wherein the surface layer portion contains inorganic particles, and the average cross-section ratio of the inorganic particles in cross sections of the surface layer portion parallel to the thickness direction and the TD direction of the resin foam composite, measured using an X-ray CT scanner, is 30% or less. [2] The resin foam composite according to [1], wherein the volume ratio of the inorganic particles to the total volume of the resin foam composite is 0.02% or more. [3] The resin foam composite according to [1] or [2], wherein the content of the inorganic particles is 0.01 parts by mass or more per 100 parts by mass of the resin foam composite. [4] The resin foam composite according to any of [1] to [3], wherein the resin foam composite has a tensile strength in the MD direction of 1.0 MPa or more and a tensile strength in the TD direction of 0.6 MPa or more at 23°C. [5] The resin foam composite according to any one of [1] to [4], wherein the surface of the surface layer portion opposite to the surface on the foam layer side has an arithmetic mean surface roughness Sa of 5 μm to 350 μm. [6] The resin foam composite according to any one of [1] to [5], wherein the inorganic particles are porous particles.

[0008] According to the present invention, it is possible to provide a resin foam composite article that can suppress odor generation, can prevent wrinkles from occurring during winding and unwinding, and has excellent handleability.

[0009] 1 shows one embodiment of a resin foam composite article of the present invention. 2 shows a modified example of a resin foam composite article of the present invention. 3 shows a modified example of a resin foam composite article of the present invention. 4 shows a modified example of a resin foam composite article of the present invention.

[0010] [Resin Foam Composite Product] As shown in FIG. 1 , a resin foam composite product 10 of the present invention includes a foam layer 11 and a surface layer portion 12 provided on at least one side of the foam layer 11, the surface layer portion 12 containing inorganic particles. While FIG. 1 shows an embodiment in which the surface layer portion 12 is provided on only one side of the foam layer 11, the surface layer portion 12 may be provided on both sides of the foam layer 11. This also applies to the modified examples described below. Furthermore, the resin foam composite product 10 has an average inorganic particle cross-section ratio of 30% or less in cross sections of the surface layer portion parallel to the thickness direction and TD direction of the resin foam composite, as measured using an X-ray CT scanner. Note that MD refers to the machine direction, which is the same as the extrusion direction, etc. TD refers to the transverse direction, which is perpendicular to the MD direction and parallel to the resin foam composite. In this specification, the term "surface layer portion" refers to the entire range from the outermost surface (the surface opposite to the surface in contact with the foam layer) to the boundary surface with the foam layer, i.e., the range indicated by reference numeral 20 in FIG. 1.

[0011] (Inorganic Particles) The inorganic particles contained in the surface layer of the resin foam composite of the present invention are not particularly limited, but are preferably porous particles. Examples of porous particles include mesoporous silica, silica gel, fumed silica, artificially synthesized zeolite, naturally occurring zeolite, activated carbon, Montrollonite, hydrotalcite, diatomite, clinker ash, fly ash, aluminum oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, titanium oxide, zirconium oxide, aluminum hydroxide, magnesium hydroxide, strontium hydroxide, barium hydroxide, zirconium hydroxide, zirconium phosphate, titanium phosphate, aluminum phosphate, metal-organic framework MOF, porous crystalline aluminum phosphate ALPO, and porous crystalline silicoaluminophosphate SAPO. These may be used alone or in combination of two or more. Also usable are layered particles of the above-listed compounds, core-shell particles synthesized using them as a template, hollow particles, agglomerated particles, and fused alloys. Among these, silica gel, zeolite, aluminum oxide, and activated carbon are preferred, with silica gel, zeolite, and aluminum oxide being more preferred, and zeolite being even more preferred. The inclusion of inorganic particles in the surface layer portion can effectively suppress odor generation from the resin foam composite. Furthermore, silica gel, zeolite, and aluminum oxide are preferably porous particles, from the viewpoint of more effectively suppressing odor generation. Furthermore, the inclusion of inorganic particles imparts stiffness to the entire resin foam composite, thereby preventing, for example, creases from being generated during unwinding or buckling when wound into a roll. The odor generated by the resin foam composite is not particularly limited, and examples include those generated by the resin in the foam layer or surface layer portion, additives such as foaming agents blended into the resin, and decomposition products thereof. Volatile components such as VOCs contained in the resin foam composite can also be odor-causing substances.

[0012] The average proportion of inorganic particle cross sections in the cross sections of the surface layer portion parallel to the thickness direction (ZD) and TD directions of the resin foam composite 10, as measured using an X-ray CT scanner, is 30% or less. If the proportion of inorganic particle cross sections in the cross section of the surface layer portion 12 exceeds 30%, the surface smoothness of the surface layer portion 12 is impaired, making it difficult to bond to the foam layer 11 when producing the resin foam composite 10. Furthermore, the flexibility of the surface layer portion 12 is impaired, making it brittle and making it difficult to handle. From this perspective, the proportion of inorganic particle cross sections in the cross section of the surface layer portion 12 is preferably 28% or less, more preferably 25% or less. On the other hand, the proportion of inorganic particle cross sections in the cross section of the surface layer portion 12 is preferably 3% or more, more preferably 5% or more, and even more preferably 6% or more. By setting the above-mentioned proportion of the cross section of the inorganic particles in the cross section of the surface layer portion 12 to a certain amount or more, the odor of the resin foam composite 10 can be sufficiently suppressed, and it becomes easier to prevent creases from occurring when the resin foam composite is unwound or buckling from occurring when the resin foam composite is wound up.

[0013] The proportion of inorganic particles in the cross section of the surface layer portion 12 can be measured as follows. Using an X-ray CT device, 1,050 images of the cross section of the surface layer portion 12 parallel to the thickness direction (ZD) and TD directions of the resin foam composite article 10 are obtained while shifting the position in the MD direction of the resin foam composite article 10. Next, for each image, the proportion of inorganic particles in the cross section of the surface layer portion 12 is measured. The average value of the proportion of inorganic particles in the cross sections of the 1,050 surface layer portions 12 is then taken as the average proportion of inorganic particles in the cross sections. Specifically, this can be measured by the method described in the Examples below. The proportion of inorganic particles in the cross sections can be adjusted by the average particle size and blending amount of the inorganic particles.

[0014] The volume ratio of the inorganic particles to the total volume of the resin foam composite 10, as measured using an X-ray CT scanner, is preferably 0.02% or more. When the volume ratio of the inorganic particles to the total volume of the resin foam composite 10 is 0.02% or more, the odor of the resin foam composite 10 can be further suppressed, and the occurrence of creases due to folding during unwinding and buckling during winding can be more effectively prevented. From this perspective, the volume ratio of the inorganic particles to the total volume of the resin foam composite 10 is more preferably 0.05% or more, even more preferably 1.5% or more, and even more preferably 2% or more. Furthermore, the volume ratio of the inorganic particles to the total volume of the resin foam composite 10 is preferably 30% or less, more preferably 25% or less, and even more preferably 20% or less. By setting the volume ratio of the inorganic particles to the total volume of the resin foam composite 10 to a certain amount or less, the surface smoothness and handleability of the resin foam composite 10 can be improved.

[0015] The volume ratio of inorganic particles to the total volume of the resin foam composite article 10 can be measured as follows. A three-dimensional image of the resin foam composite article 10 is obtained, allowing the inorganic particles to be observed through the resin foam composite article 10. Then, from the three-dimensional image, the total volume of the resin foam composite article 10 and the total volume of all inorganic particles are measured, and the total volume of all inorganic particles is divided by the total volume of the resin foam composite article 10 to calculate the volume ratio of inorganic particles to the total volume of the resin foam composite article 10. Specifically, the volume ratio of inorganic particles to the total volume of the resin foam composite article 10 can be measured by the method described in the Examples below. The volume ratio of inorganic particles to the total volume of the resin foam composite article 10 can be adjusted by the average particle size and blending amount of the inorganic particles.

[0016] In the entire resin foam composite, the content of inorganic particles is preferably 0.01 parts by mass or more per 100 parts by mass of the resin foam composite. When the content of inorganic particles per 100 parts by mass of the resin foam composite is 0.01 parts by mass or more, the odor of the resin foam composite 10 can be further suppressed, and the occurrence of creases during unwinding and buckling during winding can be more effectively prevented. From this perspective, the content of inorganic particles per 100 parts by mass of the resin foam composite is more preferably 0.05 parts by mass or more, even more preferably 0.2 parts by mass or more, and even more preferably 1 part by mass or more. On the other hand, the content of inorganic particles per 100 parts by mass of the resin foam composite is preferably 15 parts by mass or less, more preferably 10 parts by mass or less, and even more preferably 8 parts by mass or less. By setting the content of inorganic particles per 100 parts by mass of the resin foam composite to a certain amount or less, the surface smoothness and handleability of the resin foam composite 10 can be improved.

[0017] The content of inorganic particles in the surface layer portion relative to 100 parts by mass of resin is preferably 0.01 parts by mass or more. When the content of inorganic particles is 0.01 parts by mass or more, the odor of the resin foam composite article 10 can be further suppressed, and the occurrence of creases due to folding during unwinding and buckling during winding can be more effectively prevented. Furthermore, when the content of inorganic particles is 30 parts by mass or less, the surface smoothness of the resin foam composite article 10 can be improved. From the above viewpoints, the content of inorganic particles in the surface layer portion relative to 100 parts by mass of resin is more preferably 0.1 to 30 parts by mass, even more preferably 1 to 20 parts by mass, and even more preferably 5 to 20 parts by mass.

[0018] The average particle diameter of the inorganic particles is preferably 0.01 μm or more. When the average particle diameter of the inorganic particles is 0.01 μm or more, mixing of the inorganic particles with the resin becomes easier. From this viewpoint, the average particle diameter of the inorganic particles is more preferably 0.1 μm or more, and even more preferably 0.5 μm or more. Furthermore, the average particle diameter of the inorganic particles is preferably 100 μm or less. When the average particle diameter of the inorganic particles is 100 μm or less, the specific surface area of ​​the inorganic particles increases, further enhancing the deodorizing effect of the inorganic particles. From this viewpoint, the average particle diameter of the inorganic particles is more preferably 80 μm or less, and even more preferably 50 μm or less. The average particle diameter of the inorganic particles 121 refers to the cumulative median diameter measured using a scanning electron microscope, a particle size distribution diameter measuring instrument, or the like.

[0019] When porous particles are included as inorganic particles, the average pore diameter of the porous particles is preferably 4 Å or more, more preferably 7 Å or more, and even more preferably 10 Å or more. When the average pore diameter of the porous particles is equal to or greater than the above-mentioned lower limit, odor of the resin foam composite product 10 is more easily suppressed. Furthermore, the average pore diameter of the porous particles is, for example, 150 Å or less, preferably 100 Å or less, and more preferably 90 Å or less. The average pore diameter of the porous particles can be obtained by measurement using a gas adsorption method (see JIS Z 8831).

[0020] (Surface Layer Portion) The surface layer portion 12 is not particularly limited, but is preferably a non-foamed material. The resin constituting the surface layer portion 12 is preferably a thermoplastic resin. The use of a thermoplastic resin makes it easier to laminate the surface layer portion 12 to the foam layer 11 by thermocompression bonding, coextrusion, or the like. Examples of thermoplastic resins include thermoplastic elastomers such as olefin-based thermoplastic elastomers (TPO), styrene-based thermoplastic elastomers, ester-based thermoplastic elastomers, and amide-based thermoplastic elastomers; polyolefin-based resins such as polypropylene-based resins, polyethylene-based resins, and poly(1-)butene resins; acrylonitrile-butadiene-styrene (ABS) resins; polycarbonate resins; polyphenylene ether resins; (meth)acrylic resins; polyamide resins; and polyvinyl chloride resins (PVC).

[0021] Among these, the thermoplastic resin is preferably at least one selected from polyolefin-based resins and olefin-based thermoplastic elastomers (TPOs), and more preferably polyethylene-based resins. The use of these resins tends to improve the flexibility and moldability of the surface layer portion 12. The olefin-based thermoplastic elastomer (TPO) can be any of a blend type, a dynamically crosslinked type, and a polymerization type. Specific examples of olefin-based thermoplastic elastomers include those containing polypropylene as a hard segment and a copolymer having ethylene, propylene, and optionally a small amount of a diene component as a soft segment. Examples of such copolymers include ethylene-propylene copolymers (EPRs) and ethylene-propylene-diene copolymers (EPDMs). Other specific examples of olefin-based thermoplastic elastomers (TPOs) include blends of polyethylene and EPR, blends of polyethylene and EPR partially crosslinked with an organic peroxide, blends of polyethylene and EPR graft-modified with an unsaturated hydroxy monomer, an unsaturated carboxylic acid derivative, or the like, and butyl-grafted polyethylene.

[0022] Furthermore, when an olefin-based thermoplastic elastomer (TPO) is used as the thermoplastic resin, it is also preferable to use it in combination with a polyolefin-based resin. When these are used in combination, the moldability into a sheet is improved, making it easier to produce a thermoplastic resin sheet. Furthermore, a thermoplastic resin sheet using these in combination is easily heat-sealed with a crosslinked polyolefin resin foam described below, making it easy to form a laminate. The polyolefin-based resin used in combination with the olefin-based thermoplastic elastomer (TPO) preferably contains at least one of a polypropylene-based resin and a polyethylene-based resin, more preferably contains both a polypropylene-based resin and a polyethylene-based resin, and even more preferably consists of a polypropylene-based resin and a polyethylene-based resin.

[0023] Examples of polypropylene-based resins include homopolypropylene, ethylene-propylene random copolymers containing propylene as the main component, and ethylene-propylene block copolymers containing propylene as the main component. These may be used alone or in combination of two or more. Of these, it is preferable to use an ethylene-propylene random copolymer containing propylene as the main component. Note that "containing propylene as the main component" means that the content of propylene-derived structural units in the polypropylene-based resin is 75% by mass or more, preferably 90% by mass or more, of all monomer-derived structural units. The same applies hereinafter.

[0024] The polyethylene resin is not particularly limited, but examples thereof include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ethylene-α-olefin copolymers containing ethylene as a main component, which may be used alone or in combination of two or more. Among the above-mentioned polyethylene resins, linear low-density polyethylene is preferred.

[0025] When an olefin-based thermoplastic elastomer (TPO) and a polyolefin-based resin are used in combination, the content of the olefin-based thermoplastic elastomer (TPO) is preferably 5 to 95 mass %, more preferably 10 to 90 mass %, based on the total amount of the thermoplastic resin. The content of the polyolefin-based resin is preferably 5 to 95 mass %, more preferably 10 to 90 mass %, based on the total amount of the thermoplastic resin.

[0026] The resin of the surface layer may contain an additive as appropriate. The additives used may be the same as those used in the foam layer described below.

[0027] <Arithmetic Mean Surface Roughness Sa> The arithmetic mean surface roughness Sa of the surface of the surface layer 12 opposite the surface facing the foam layer 11 is preferably 5 to 350 μm, more preferably 7 to 250 μm, and even more preferably 8 to 200 μm. When the arithmetic mean surface roughness Sa of the surface of the surface layer 12 opposite the surface facing the foam layer 11 is within the above range, the surface smoothness of the surface layer 12 is improved, making it easier to bond to the foam layer 11 when producing the resin foam composite 10. The arithmetic mean surface roughness Sa can be adjusted by the type, particle size, and amount of inorganic particles used in the surface layer. The arithmetic mean surface roughness Sa of the surface layer 12 can be measured by the method described in the Examples below.

[0028] <Thickness> The thickness of the surface layer portion 12 is not particularly limited, but is preferably 25 to 150 μm, more preferably 30 to 130 μm, and even more preferably 45 to 120 μm. When the thickness of the foam 12 is within the above range, the inorganic particles contained in the surface layer portion 12 tend to appropriately suppress odor generation, and the surface layer portion 12 also tends to suppress the occurrence of buckling wrinkles during unwinding. Furthermore, the resin foam composite tends to be easy to handle.

[0029] (Foam Layer) The foam constituting the foam layer 11 is not particularly limited. Examples of foams constituting the foam layer 11 include polyolefin resin foam, polystyrene foam, polyurethane foam, phenolic resin foam, urea resin foam, epoxy resin foam, acrylic resin foam, rubber foam, polyvinyl chloride foam, polyamide resin foam, polyimide resin foam, polyvinyl alcohol resin foam, ionomer foam, pyranyl resin foam, and silicone resin foam. These foams can be used alone or in combination of two or more. Among these foams, polyolefin resin foam is preferred, and crosslinked polyolefin resin foam is more preferred.

[0030] (Crosslinked polyolefin resin foam) In the present invention, the crosslinked polyolefin resin foam used in the foam layer 11 is obtained by crosslinking and foaming a foamable resin composition containing a polyolefin resin. Hereinafter, each component contained in the foamable resin composition when the foam is a crosslinked polyolefin resin foam will be described in detail.

[0031] (Polyolefin Resin) Examples of the polyolefin resin contained in the foamable resin composition include polyethylene-based resins, polypropylene-based resins, ethylene vinyl acetate resins, etc. From the viewpoint of improving the heat resistance and moldability of the resulting crosslinked polyolefin resin foam, the polyolefin resin preferably contains a polypropylene-based resin, and more preferably contains both a polypropylene-based resin and a polyethylene-based resin.

[0032] Examples of polypropylene-based resins include homopolypropylene, ethylene-propylene random copolymers containing propylene as the main component, and ethylene-propylene block copolymers containing propylene as the main component. These may be used alone or in combination of two or more. Among these, it is preferable to use an ethylene-propylene random copolymer containing propylene as the main component. The melt flow rate (hereinafter referred to as "MFR") of the polypropylene-based resin is preferably 70 g / 10 min or less, more preferably 50 g / 10 min or less, and even more preferably 25 g / 10 min or less. The lower limit of the MFR is usually 0.1 g / 10 min. The MFR is a value measured in accordance with JIS K 7210 under conditions of a temperature of 230°C and a load of 21.2 N.

[0033] The polyethylene resin is not particularly limited, but examples thereof include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ethylene-α-olefin copolymers containing ethylene as the main component, which may be used alone or in combination of two or more. Among the above-mentioned polyethylene resins, linear low-density polyethylene is preferred. The density of linear low-density polyethylene is 0.900 to 0.925 g / cm. ３ is preferably 0.902 to 0.922 g / cm ３ The MFR of the polyethylene resin is preferably 0.5 to 70 g / 10 min, and more preferably 1.5 to 50 g / 10 min. The MFR is a value measured in accordance with JIS K 7210 under conditions of a temperature of 190°C and a load of 21.2 N.

[0034] When the polyolefin resin contains a polypropylene-based resin, the content is not particularly limited, but from the viewpoint of improving heat resistance, the resin in the foamable resin composition preferably contains 50% by mass or more of the polypropylene-based resin, more preferably 55% by mass or more, and even more preferably 60% by mass or more. Furthermore, the content of the polypropylene-based resin in the resin in the foamable resin composition may be 100% by mass or less, but is preferably 90% by mass or less, and more preferably 80% by mass or less.

[0035] When the polyolefin resin contains a polypropylene-based resin, the resin in the foam may further contain a resin other than a polypropylene-based resin. Specific examples include polyolefin-based resins other than polypropylene-based resins, such as polyethylene-based resins, and olefin-based elastomers. The total content of the polyolefin-based resin other than a polypropylene-based resin and the olefin-based elastomer in the foam is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 25% by mass or more, and preferably 50% by mass or less, more preferably 45% by mass or less, and even more preferably 40% by mass or less. Examples of olefin-based elastomers include ethylene-propylene-diene rubber (EPDM), ethylene-propylene rubber (EPM), and olefin-based thermoplastic elastomers. Details of the olefin-based thermoplastic elastomer are as described above for the surface layer portion. The foamable resin composition may also contain a resin other than a polyolefin resin and an olefin-based elastomer.

[0036] <Antioxidant> The foamable resin composition used for the crosslinked polyolefin resin foam preferably contains an antioxidant. The inclusion of an antioxidant can suppress oxidative degradation of the polyolefin resin and further reduce odor generation from the crosslinked polyolefin resin foam. The antioxidant is preferably contained in an amount of 0.5 to 5.0 parts by mass, more preferably 1.0 to 4.0 parts by mass, per 100 parts by mass of resin. By using 0.5 parts by mass or more of antioxidant per 100 parts by mass of resin, oxidative degradation of the polyolefin resin can be further suppressed and odor generation from the crosslinked polyolefin resin foam can be further reduced. Furthermore, by using 5.0 parts by mass or less of antioxidant per 100 parts by mass of resin, it is possible to prevent excess antioxidant from becoming an odorous substance.

[0037] The type of antioxidant is not particularly limited, and examples thereof include phenolic antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and amine-based antioxidants. Among these, at least one selected from phenolic antioxidants and phosphorus-based antioxidants is preferred, and among these, phenolic antioxidants are more preferred from the viewpoint of reducing odor generation of crosslinked polyolefin resin foams. Examples of phenolic antioxidants include 2,6-di-tert-butyl-p-cresol, n-octadecyl-3-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, 2-tert-butyl-6-(3-tert-butyl-2-hydroxy-5-methylbenzyl)-4-methylphenyl acrylate, and tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane. Among these, tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane is preferred. One type of antioxidant may be used alone, or two or more types may be used in combination.

[0038] <Crosslinking Auxiliary Agent> The foamable resin composition preferably contains a crosslinking auxiliary agent. The content of the crosslinking auxiliary agent in the foamable resin composition is preferably 2.0 to 5.0 parts by mass, more preferably 2.5 to 4.7 parts by mass, per 100 parts by mass of resin. By using 2.0 parts by mass or more of the crosslinking auxiliary agent per 100 parts by mass of resin, the generation of odor-causing substances in the foam can be reduced. This is thought to be because the progress of crosslinking of the resin to a certain extent suppresses deterioration due to heat, etc., and as a result, suppresses the generation of odor-causing substances. By using 5.0 parts by mass or less of the crosslinking auxiliary agent per 100 parts by mass of resin, poor foaming can be easily prevented. Furthermore, by setting the amount of crosslinking auxiliary in the foamable resin composition within this range and the amount of antioxidant within the above range, the generation of odor-causing substances in the foam can be suppressed, thereby more effectively reducing the generation of odor in the foam.

[0039] Examples of cross-linking aids include polyfunctional (meth)acrylate compounds such as trifunctional (meth)acrylate compounds and bifunctional (meth)acrylate compounds, and compounds having three functional groups per molecule. Other cross-linking aids include compounds having two functional groups per molecule, such as divinylbenzene, diallyl phthalate, diallyl terephthalate, diallyl isophthalate, ethylvinylbenzene, lauryl methacrylate, and stearyl methacrylate. Examples of trifunctional (meth)acrylate compounds include trimethylolpropane trimethacrylate and trimethylolpropane triacrylate. Examples of bifunctional (meth)acrylate compounds include 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, and neopentyl glycol dimethacrylate. Examples of compounds having three functional groups per molecule include trimellitic acid triallyl ester, 1,2,4-benzenetricarboxylic acid triallyl ester, and triallyl isocyanurate. The cross-linking aids can be used alone or in combination of two or more. Among these, from the viewpoint of reducing odor generation of the foam, polyfunctional (meth)acrylate compounds are preferred, bifunctional (meth)acrylate compounds are more preferred, and 1,9-nonanediol dimethacrylate is even more preferred.

[0040] <Foaming Agent> Methods for foaming a foamable resin composition include chemical foaming and physical foaming. The chemical foaming method is a method in which bubbles are formed by gas generated by thermal decomposition of a compound added to the foamable resin composition, while the physical foaming method is a method in which a low-boiling-point liquid (foaming agent) is impregnated into the foamable resin composition and then the foaming agent is volatilized to form cells. The foaming method is not particularly limited, but chemical foaming is preferred. As the foaming agent, a thermal decomposition type foaming agent is preferably used, and for example, an organic or inorganic chemical foaming agent with a decomposition temperature of about 140 to 270°C can be used. Examples of organic blowing agents include azo compounds such as azodicarbonamide and azobisisobutyronitrile; nitroso compounds such as N,N'-dinitrosopentamethylenetetramine; hydrazine derivatives such as hydrazodicarbonamide, 4,4'-oxybis(benzenesulfonylhydrazide) and toluenesulfonylhydrazide; semicarbazide compounds such as toluenesulfonylsemicarbazide; and guanidine salt compounds such as ammonium nitrite, ammonium carbonate, ammonium hydrogencarbonate, guanidine phosphate, guanidine bicarbonate, guanidine carbonate, guanidine hydrochloride, and guanidine sulfate.

[0041] Examples of inorganic foaming agents include sodium carbonate, sodium bicarbonate, sodium borohydride, and anhydrous monosodium citrate. Among these, from the viewpoints of obtaining fine bubbles and from the viewpoints of economy and safety, azo compounds and nitroso compounds are preferred, with azodicarbonamide, azobisisobutyronitrile, and N,N'-dinitrosopentamethylenetetramine being more preferred, and azodicarbonamide being particularly preferred. The foaming agents can be used alone or in combination of two or more. The amount of foaming agent added to the foamable resin composition is not particularly limited, but from the viewpoint of easily adjusting the expansion ratio of the foam to the above range, it is preferably 1 to 20 parts by mass, more preferably 2 to 15 parts by mass, and even more preferably 3 to 12 parts by mass per 100 parts by mass of the resin.

[0042] <Other Additives> The foamable resin composition may contain additives that are generally used in foams, such as a heat stabilizer, a colorant, a flame retardant, an antistatic agent, a filler, a rust inhibitor, and a decomposition temperature adjuster, as needed.

[0043] <Inorganic Particles> In the foam layer, i.e., the expandable resin composition, the content of inorganic particles per 100 parts by mass of resin is preferably less than the content of inorganic particles per 100 parts by mass of resin in the surface layer portion described above. It is more preferable that the foam layer, i.e., the expandable resin composition, is substantially free of the inorganic particles described above. By reducing the content of inorganic particles in the foam layer 11 and by substantially eliminating the inorganic particles, the foam layer 11 is endowed with a certain degree of flexibility, which makes it easier to prevent creases from forming during unwinding and buckling during winding. Furthermore, the inorganic particles are less likely to capture the foaming gas generated during the expansion of the expandable resin composition, improving foamability. This also prevents the inorganic particles from being used for purposes other than odor absorption, allowing for effective odor absorption by the inorganic particles. In addition, "substantially free of inorganic particles" means that the content of inorganic particles is less than 3 parts by mass, preferably less than 1 part by mass, more preferably less than 0.1 parts by mass, and even more preferably 0 parts by mass, per 100 parts by mass of resin.

[0044] <Closed Cell Ratio> The closed cell ratio of the crosslinked polyolefin resin foam is preferably 70% or more. A closed cell ratio of 70% or more can further reduce the odor generation of the foam. From the viewpoint of further reducing the odor generation, the closed cell ratio of the foam is more preferably 80% or more, and even more preferably 90% or more. The closed cell ratio can be measured by the following method. A test piece having a flat square shape with a side length of 5 cm and a constant thickness was cut out from a resin foam sheet. The thickness of the test piece was measured, and the apparent volume V1 of the test piece was calculated, and the weight W1 of the test piece was also measured. Next, the apparent volume V2 occupied by the bubbles was calculated based on the following formula. The density of the resin constituting the test piece was 1 g / cm ３The apparent volume occupied by the bubbles was V2 = V1 - W1. Next, the test piece was submerged in distilled water at 23°C to a depth of 100 mm from the water surface, and a pressure of 15 kPa was applied to the test piece for 3 minutes. After the pressure was released in the water, the test piece was removed from the water and the water adhering to the surface of the test piece was removed. The weight W2 of the test piece was measured, and the open cell fraction F1 and closed cell fraction F2 were calculated based on the following formulas: Open cell fraction F1 (%) = 100 x (W2 - W1) / V2 Closed cell fraction F2 (%) = 100 - F1

[0045] <Expansion Ratio> The expansion ratio of the crosslinked polyolefin resin foam is not particularly limited, but is preferably 8 to 30 times, more preferably 9 to 28 times, and even more preferably 9.5 to 27 times. When the expansion ratio is a certain level or higher, flexibility of the foam can be easily ensured. When the expansion ratio is a certain level or lower, the mechanical strength of the foam can be improved. The expansion ratio is calculated as the ratio of the specific volume (unit: cm) of the resin composition before foaming to the foam after foaming. ３ / g) and the specific volume of the foam can be calculated by dividing the specific volume of the resin composition before foaming by the specific volume of the foam.

[0046] <Degree of Crosslinking> The degree of crosslinking of the crosslinked polyolefin resin foam of the present invention is preferably 20 to 70% by mass. A degree of crosslinking of 20 to 70% by mass allows the foam to have a well-balanced improvement in mechanical strength, flexibility, and moldability. From the viewpoint of a well-balanced improvement in mechanical strength, flexibility, and moldability of the foam, the degree of crosslinking of the crosslinked polyolefin resin foam of the present invention is more preferably 30 to 60% by mass, and even more preferably 35 to 55% by mass. The degree of crosslinking can be measured by the following method. A test piece of about 100 mg was taken from the foam, and the mass A (mg) of the test piece was precisely weighed. Next, this test piece was immersed in 30 cm of xylene at 120°C. ３ After immersion for 24 hours, the insoluble matter on the mesh was filtered through a 200-mesh wire netting, vacuum-dried, and the mass B (mg) of the insoluble matter was precisely weighed. From the obtained value, the degree of crosslinking (mass%) can be calculated using the following formula: Degree of crosslinking (mass%) = 100 × (B / A).

[0047] <Thickness> The thickness of the foam layer 11 is not particularly limited, but is preferably 1 to 5 mm, more preferably 1.2 to 4 mm, and even more preferably 1.5 to 3.5 mm.

[0048] <Thickness Ratio> The ratio of the thickness of the foam layer 11 to the thickness of the surface layer portion 12 (foam layer / surface layer portion) is not particularly limited, but is preferably 1 to 200, more preferably 5 to 100, and even more preferably 10 to 50. By setting the thickness ratio within the above range, the thickness of the surface layer portion 12 becomes appropriate, and the inorganic particles contained in the surface layer portion 12 tend to appropriately suppress the generation of odor. In addition, the surface layer portion 12 also tends to suppress the occurrence of buckling wrinkles during unwinding.

[0049] <Tensile strength> The resin foam composite article 10 of the present invention preferably has a tensile strength in the MD direction of 1.0 MPa at 23°C. When the tensile strength in the MD direction of the resin foam composite article 10 at 23°C is 1.0 MPa or more, the resin foam composite article 10 can be prevented from being damaged, buckled, or broken when the resin foam composite article 10 is wound or unwound. From this perspective, the tensile strength in the MD direction of the resin foam composite article 10 of the present invention at 23°C is more preferably 1.2 MPa or more, and even more preferably 1.6 MPa or more. The upper limit of the range of the tensile strength in the MD direction of the resin foam composite article 10 of the present invention at 23°C is not particularly limited, but is typically 10 MPa. The tensile strength in the MD direction of the resin foam composite article 10 of the present invention at 23°C can be measured by the method described in the Examples below. The tensile strength in the MD direction of the resin foam composite 10 at 23°C can be adjusted by the composition of the foam layer 11, the expansion ratio, the degree of crosslinking, the composition of the surface layer 12, the type and amount of inorganic particles, etc.

[0050] The resin foam composite article 10 of the present invention preferably has a TD tensile strength of 0.6 MPa or more at 23°C. When the TD tensile strength of the resin foam composite article 10 of the present invention is 0.6 MPa or more at 23°C, the resin foam composite article 10 can be prevented from being damaged, buckled, or broken when the resin foam composite article 10 is wound or unwound. From this perspective, the TD tensile strength of the resin foam composite article 10 of the present invention at 23°C is more preferably 0.7 MPa or more, and even more preferably 1.0 MPa or more. The upper limit of the TD tensile strength of the resin foam composite article 10 of the present invention at 23°C is not particularly limited, but is typically 10 MPa. The TD tensile strength of the resin foam composite article 10 of the present invention at 23°C can be measured by the method described in the Examples below. The tensile strength in the TD direction of the resin foam composite 10 at 23°C can be adjusted by the composition of the foam layer 11, the expansion ratio, the degree of crosslinking, the composition of the surface layer 12, the type and amount of inorganic particles, etc.

[0051] The resin foam composite article 10 of the present invention preferably has tensile strengths in both the MD and TD directions that satisfy the above ranges at 23° C. That is, the tensile strength in the MD direction is preferably 1.0 MPa or more and the tensile strength in the TD direction is preferably 0.6 MPa or more. When the tensile strength in the MD and the tensile strength in the TD direction both satisfy the above ranges, the above effects are more easily exhibited.

[0052] [Method for manufacturing resin foam composite product] (1) Manufacturing method 1 The method for manufacturing the resin foam composite product of the present invention is not particularly limited, but it can be manufactured by, for example, a method in which a layer made of a foamable resin composition and a surface layer portion are laminated to obtain a laminate sheet, and then the foamable resin composition of the laminate sheet is foamed (hereinafter also referred to as "manufacturing method 1").

[0053] More specifically, the manufacturing method 1 includes the following steps (I) to (II): (I) a step of obtaining a laminate sheet having a layer made of a foamable resin composition and a surface layer portion formed on one side of the layer; and (II) a step of obtaining a resin foam composite by foaming the layer made of the foamable resin composition of the laminate sheet.

[0054] Each step is described below. (Step (I)) The method for obtaining the laminate sheet in step (I) is not particularly limited, but co-extrusion molding is preferred. Specifically, when surface layer portions are formed on both sides of a layer made of a foamable resin composition, the resin for forming the surface layer portions, inorganic particles, and optional additives are supplied to the first and third extruders, respectively, and melt-kneaded to obtain a resin composition for forming the surface layer portions. The resin for forming the foam layer, a foaming agent such as a thermally decomposable foaming agent, and optional antioxidants, cross-linking aids, and other additives are supplied to the second extruder and melt-kneaded to obtain a foamable composition for forming the foam layer. Next, the compositions supplied from the first to third extruders are merged so that the composition supplied from the second extruder forms the middle layer, and the resulting mixture is extruded into a sheet using a T-die or the like to obtain a three-layer laminate sheet. However, in a method for obtaining a three-layer laminate sheet, if the composition of both surface layer portions is the same, two extruders (first and third extruders) may not be used, but one extruder may be used, and the resin composition of both surface layer portions may be supplied from that one extruder.

[0055] Furthermore, when a surface layer portion is formed on one side of a layer made of a foamable composition, the resin for forming the surface layer portion, inorganic particles, and additives as needed are fed into a first extruder and melt-kneaded to obtain a resin composition for forming the surface layer portion. The resin for forming the foam layer, a foaming agent such as a thermally decomposable foaming agent, and antioxidants, crosslinking aids, and other additives as needed are fed into a second extruder and melt-kneaded to obtain a foamable resin composition for forming the foam layer. The resin composition fed from the first extruder is then merged with the composition fed from the second extruder and extruded into a sheet using a T-die or the like to obtain a two-layer multilayer laminate sheet. In co-extrusion molding, either a feedblock method or a multi-manifold method may be used, but the feedblock method is preferred. In step (I), if at least one of the surface layer portion and the foam layer is made multilayered as described below, the number of layers extruded from the extruder may be appropriately increased.

[0056] In step (I), when the foam of the foam layer is a crosslinked polyolefin resin foam, it is preferable to further crosslink the laminate sheet obtained above. Although a crosslinking method may involve blending an organic peroxide in advance and heating the laminate sheet obtained in step (I) to crosslink, it is preferable to crosslink the laminate sheet by irradiating it with ionizing radiation. Examples of ionizing radiation include electron beams and β rays, with electron beams being preferred. When the foam of the foam layer is a crosslinked polyolefin resin foam, the exposure dose of ionizing radiation is preferably 1 to 10 Mrad, more preferably 1.5 to 5 Mrad.

[0057] (Step (II)) In step (II), the laminate sheet obtained in step (I) is foamed to foam the layer comprising the foamable resin composition. The layer comprising the foamable resin composition may be foamed by treating it so that the foaming agent foams. When the foaming agent is a thermally decomposable foaming agent, the foaming is achieved by heating the laminate sheet. The heating temperature may be equal to or higher than the temperature at which the thermally decomposable foaming agent decomposes. When the foam of the foam layer is a crosslinked polyolefin resin foam, the heating temperature is, for example, about 150 to 320°C. The method for heating the laminate sheet is not particularly limited, and examples include a method of heating the laminate sheet with hot air, infrared radiation, a salt bath, and an oil bath, and these methods may be used in combination. The laminate sheet may also be appropriately stretched during or after foaming.

[0058] (2) Manufacturing Method 2 The resin foam composite article of the present invention can also be manufactured by another method. Specifically, a foam constituting the foam layer is manufactured in advance, and a resin layer (surface layer portion) is superimposed on and bonded to the surface of the foam (foam layer) (hereinafter also referred to as "Manufacturing Method 2").

[0059] In the production method 2, a foam may be obtained by melt-kneading a resin for forming the foam layer, a thermally decomposable foaming agent, and additives blended as necessary to obtain a foamable resin composition for forming the foam layer, and then molding the foamable resin composition into a sheet (foamable resin composition sheet). The method for melt-kneading the foamable resin composition and molding it into a sheet is not particularly limited, but it is preferably carried out using an extruder.

[0060] When the foam of the foam layer is a crosslinked polyolefin resin foam, the obtained foamable resin composition sheet is preferably further crosslinked before foaming, as described below. Although the crosslinking method may involve blending an organic peroxide in advance and heating the foamable resin composition sheet to crosslink it, it is preferred to crosslink the foamable resin composition sheet by irradiating it with ionizing radiation. The type and dose of ionizing radiation are as described in the above-mentioned Production Method 1.

[0061] Next, the foamable resin composition sheet may be foamed. The layer made of the foamable resin composition may be treated so that the foaming agent foams. When the foaming agent is a thermally decomposable foaming agent, the multilayer laminate sheet is heated to foam it. The heating temperature and heating method are as described in the above-mentioned Production Method 1. The foamable resin composition sheet may be appropriately stretched during or after foaming.

[0062] Thereafter, a separately prepared resin film for forming the surface layer portion is superimposed on the foam for forming the foam layer and bonded to obtain a resin foam composite. Specifically, heat and pressure may be applied using a press, laminar, or the like to achieve thermocompression bonding. Alternatively, a pressure-sensitive adhesive, adhesive, or the like may be applied to the bonding surface between the foam layer and the resin layer, or double-sided adhesive tape may be applied to bond them together using the pressure-sensitive adhesive, adhesive, double-sided adhesive tape, or the like. Note that when at least one of the foamable layer and the surface layer portion has a multilayer structure as described below, it is preferable to bond layers of the same type (foam layers or surface layer portions) together using the same method as described above during the superposition.

[0063] The resin foam composite of the present invention is preferably produced by Production Method 2. In the production process of a resin foam composite, gases derived from the blowing agent, etc., may be generated when the foamable resin composition is foamed to obtain a foam layer. However, in Production Method 2, the foam layer is obtained before laminating the foam layer and the surface layer portion, and therefore the gases are not adsorbed by the inorganic particles contained in the surface layer portion during production. Therefore, production by Production Method 2 makes it easier to more effectively suppress odor generation from the resin foam composite without losing the adsorption performance of the inorganic particles during production.

[0064] [Modifications] In the above-described embodiments of the resin foam composite of the present invention, the foam layer and the surface layer portion are each a single layer. However, at least one of the foam layer and the surface layer portion may be multilayered. When the foam layer is multilayered, for example, as shown in FIG. 2, a resin foam composite 10A may include two foam layers 11a and 11b. When the surface layer portion is multilayered, for example, as shown in FIG. 3, a resin foam composite 10B may include two surface layer portions 12a and 12b. The area of ​​the surface layer portion in this case is the area indicated by the reference symbol 20′. In a configuration in which the surface layer portion is multilayered, inorganic particles may be contained in only one of the surface layer portions or in each of two or more surface layer portions. However, from the viewpoint of suppressing odor generation, it is preferable that inorganic particles are contained in at least the outermost layer. When surface layer portions are provided on both sides of the foam layer, the number of layers of the surface layer portion on each side may be the same or different. In the case where the number of layers of the surface layer portions is different, for example, the surface layer portion provided on one side of the foam layer may be two or more layers, and the surface layer portion provided on the other side of the foam layer may be a single layer. Furthermore, as shown in Figure 4, a resin foam composite 10C may include a foam layer 11a, a resin layer 12a (surface layer portion) provided on one side of the foam layer 11a, a resin layer 12b provided on the surface of the foam layer 11a opposite to the surface of the resin layer 12a side, and a foam layer 11b provided on the surface of the resin layer 12b opposite to the surface of the foam layer 11a side.

[0065] The resin foam composite of the present invention is preferably used as a roll product, although it is not particularly limited thereto. Because it can suppress odor generation, has good surface smoothness, and effectively prevents creases from forming during unwinding and buckling wrinkles from forming during winding, it is preferable to use it as a roll product. When using the resin foam composite as a roll product, it is preferable to wind the resin foam composite, preferably with the surface layer facing the outer periphery. Winding in this manner helps prevent buckling wrinkles from forming during winding. The resin foam composite of the present invention is also preferably used for vehicle applications, although it is not particularly limited thereto. In vehicle applications, it is preferably used to fasten vehicle-mounted components. Examples of vehicle-mounted components include vehicle interior materials, such as vehicle-mounted panels (e.g., ceiling panels, door panels, instrument panels), car air conditioners, door trims, vibration-damping components, emblems, decorative films, airbags, and water-stopping components. The vehicle-mounted components are preferably fastened to the vehicle via, for example, an adhesive or adhesive tape.

[0066] The present invention will be explained in more detail below with reference to examples, but the present invention is not limited to these examples in any way.

[0067] [Components Used] The components used in each Example and Comparative Example are as follows. (Raw Materials for Foam Layer) Polypropylene Resin (1): Homo PP, manufactured by Prime Polymer Co., Ltd., trade name "J106G", MFR 15 g / 10 min Polypropylene Resin (2): Random PP, manufactured by Sumitomo Chemical Co., Ltd., trade name "AD571", density 0.90 g / cm ３ , MFR 0.5 g / 10 min (230 ° C.) LLDPE: Linear low-density polyethylene, manufactured by Prime Polymer Co., Ltd., trade name "UltraZex 1020L", density 0.91 g / cm ３, MFR 2.0 g / 10 min (190°C) TPO: olefin-based thermoplastic elastomer, manufactured by Basell, trade name "Softell CA 02 A", MFR 0.6 g / 10 min (230°C) EPDM: Mitsui Chemicals, trade name "3045" Blowing agent: azodicarbonamide, manufactured by Otsuka Chemical, trade name "SO-L", decomposition temperature: 197°C, average particle size: 3.2 μm Phenol-based antioxidant: tetrakis[methylene-3-(3',5'-di-tert-butyl-4'-hydroxyphenyl)propionate]methane, manufactured by BASF Japan, trade name "Irganox 1010" Crosslinking aid: 1,9-nonanediol dimethacrylate, manufactured by Kyoeisha Chemical Co., Ltd., trade name "Light Ester 1,9ND", viscosity 8 mPa·s / 25°C (raw material for the surface layer) LLDPE: linear low-density polyethylene, manufactured by Prime Polymer Co., Ltd., trade name "Ultzex ​​1020L", density 0.91 g / cm ３ , MFR 2.0 g / 10 min (190°C) TPO: olefin-based thermoplastic elastomer, manufactured by Basell, trade name "Softell CA 02 A", MFR 0.6 g / 10 min (230°C) Inorganic particles (1): silica gel (SiO ２ ), manufactured by Fuji Silicia Chemical Co., Ltd., product name "SYLOPAGE 760", average particle size 5.0 μm, average pore size 25 Å ・Inorganic particles (2): Aluminum oxide (Al ２ O ３ ), manufactured by Nippon Light Metal Co., Ltd., trade name "C20", average particle size 15 to 25 μm, average pore size 85 Å. Inorganic particles (3): zeolite, manufactured by Resonac Universal Co., Ltd., trade name "13X POWDER", average particle size 3 μm, average pore size 10 Å.

[0068] Example 1 (Production of Surface Layer Portion) LLDPE and inorganic particles (1) were kneaded at 230°C using a single-screw extruder to obtain a resin sheet for the surface layer portion having a thickness of 100 μm. The amount of inorganic particles (1) was 9.89 parts by mass per 100 parts by mass of the resin foam composite. (Production of Crosslinked Polyolefin Resin Foam) A foamable resin composition was obtained by mixing polypropylene-based resin (2), LLDPE, a phenol-based antioxidant, a crosslinking aid, and a foaming agent in the proportions shown in Table 1. The resulting composition was melt-kneaded at 180°C using a single-screw extruder to obtain a foamable sheet. Both sides of the foamable sheet were irradiated with ionizing radiation (electron beam) at an acceleration voltage of 1000 keV and a dose of 2.0 Mrad to obtain a crosslinked foamable sheet. The crosslinked foamable sheet was then fed into a vertical hot air foaming oven at an oven temperature of 250°C, and heated and foamed while being stretched, to obtain a crosslinked polyolefin resin foam having a thickness of 2.5 mm. (Production of Resin Foam Composite) One surface of the crosslinked polyolefin resin foam produced as described above was heated to 160°C with far infrared rays or near infrared rays, passed through lamination rolls with a clearance of -1.0 mm, and the resin sheet for the surface layer described above was attached to the surface of the crosslinked polyolefin resin foam to produce a resin foam composite.

[0069] [Examples 2 to 7, Comparative Example 2] Surface layer portions, crosslinked polyolefin resin foams, and resin foam composites were obtained in the same manner as in Example 1, except that the types and blending amounts of the resins and inorganic particles used in preparing the surface layer portions, and the thickness of each layer, as well as the types and blending amounts of each component used in preparing the crosslinked polyolefin resin foam, were changed as shown in Tables 1 and 2.

[0070] [Comparative Examples 1 and 4] Crosslinked polyolefin resin foams were obtained in the same manner as in Example 1, except that no surface layer portion was prepared and the types and blending ratios of the components used to prepare the crosslinked polyolefin resin foam and the thickness of the crosslinked polyolefin resin foam were changed as shown in Table 2.

[0071] [Comparative Example 3] A surface layer portion, a cross-linked polyolefin resin foam, and a resin foam composite were obtained in the same manner as in Example 1, except that no inorganic particles were blended into the surface layer portion, and the types and blendings of the components used to prepare the cross-linked polyolefin resin foam, as well as the thickness of each layer, were changed as shown in Table 2.

[0072] (Area proportion of inorganic particles in cross section of surface layer) When measuring the volume of inorganic particles contained in the surface resin layer, the following X-ray CT device was used and the calculation was carried out as follows. The sample size was 0.56 mm wide and 0.51 mm long, and the thickness was the thickness of the component (resin foam composite) as shown in Table 1. The sample was positioned so that the thickness direction of the sample coincided with the Y axis. The Y axis is the direction in which the X-ray source and the camera are aligned. The measurement conditions for the X-ray CT measurement are as follows: Device name: 3D X-ray microscope ("High Resolution 3D X-ray Microscope nano3DX" manufactured by Rigaku Corporation) The measurement conditions are as follows: X-ray target: Mo Lens: L0270 (0.27 μm / pixel) Binning: 2 Exposure time: 8 seconds Number of images taken: 1050 Furthermore, for samples spanning multiple fields of view, the images obtained with the X-ray CT device were linked using image processing software ("Avizo 3D Pro 2022.1" manufactured by Thermo Fisher Scientific).

[0073] (Volume ratio of inorganic particles in the total volume of a resin foam composite) Images taken with an X-ray CT scanner were analyzed using ImageJ according to the following procedure. Set Scale was selected from the Analyze section. The reciprocal of the lens resolution equipped in the X-ray CT scanner was entered in the Distance in pixels section. For example, for the above-mentioned 0.27 μm / pixel, 3.7037 was entered. Next, the unit of length was entered in the Unit of length section. In this case, μm was used. Next, 100 white shining points on the binarized image were randomly counted, the brightness of each point was extracted, and the average brightness value was calculated. Next, the number, cross-sectional area, and volume of points showing brightness above the average on consecutive captured images were analyzed. The procedure is as follows: The "Analyze" item was selected, the "3D Objects counter" item was selected, and the threshold value and the average brightness value were entered. Next, the number of photographs taken with the X-ray CT device was entered in the "Slice" item. In this case, it was set to 1050. In the "Maps to Show" item, the "Objects" and "Surface" items were selected, and in the "Results tables to show" item, "Statistics" was selected and analysis was performed. Using the above method, the total volume of inorganic particles can be calculated. Next, ImageJ was operated, and the cross-sectional area of ​​the resin layer was obtained by selecting a rectangle where a white shining point was present on the photograph, and then the resin layer volume was calculated by multiplying it by the Z-axis length of the X-ray CT image. The volume fraction of inorganic particles in the resin layer was calculated using the following formula. Inorganic particle volume ratio (%) = total volume of inorganic particles in resin layer / resin layer volume × 100 Resin layer volume = 0.56 mm (width) × 0.51 mm (length) × resin layer thickness observed by X-ray CT

[0074] (Tensile Strength) The tensile strength of the resin foam composite products of the Examples and Comparative Examples was measured at a measurement temperature of 23°C in accordance with JIS K6767.

[0075] (Arithmetic mean value of surface roughness Sa) The arithmetic mean value of surface roughness Sa of the surface opposite to the foam layer side of the surface layer portion of the foam sheets of the Examples and Comparative Examples was measured using a laser microscope in accordance with ISO 25178. The laser microscope used and the measurement conditions are as follows: Device name: Controller "VK-X1000", head "VK-X1000", manufactured by Keyence Corporation Measurement mode: Outermost surface measurement Lens used: Standard 5x lens Laser light source: Red semiconductor laser (wavelength 661 nm)

[0076] (Odor evaluation of a resin foam composite product at the center of a roll product) A 10 cm x 10 cm piece was cut out from any position in the center of the roll product. The cut test piece was placed in a sealed 1 L glass air-collecting bottle and heated at 100°C for 2 hours, then cooled to 60°C. After cooling, the lid was opened and the odor was evaluated. If the odor intensity was lower than that of the evaluation reagent prepared by the following procedure, it was rated as A, and if it was higher or the same, it was rated as B. The evaluation was performed by at least three evaluators, and an average evaluation method was used. The method for preparing the evaluation reagent is described below. 1.0 mL of n-butanol was dropped into a 1 L glass bottle, and then 100 mL of pure water was added. The mixture was then thoroughly stirred.

[0077] (Presence or absence of fracture and peeling of resin foam composite) Masking tape (Fitlite Tape No. 738, manufactured by Sekisui Chemical Co., Ltd.) was applied to the surface side of the resin foam composite, and the resin foam composite was left in an environment of 23°C and 50% RH. After one day, the resin foam composite was manually peeled off from the masking tape and evaluated for fracture and peeling of the surface layer. The evaluation criteria are as follows: A: Neither fracture nor peeling of the surface layer occurred in the resin foam composite. B: At least one of fracture and peeling of the surface layer occurred in the resin foam composite.

[0078] (Presence or absence of wrinkles when winding and unwinding roll product) When a resin foam composite product was formed into a roll, the presence or absence of wrinkles when it was wound at 120 N and unwinding was evaluated. The evaluation criteria were as follows: A: Neither buckling wrinkles when winding nor folding wrinkles when unwinding occurred. B: At least one of buckling wrinkles when winding and folding wrinkles when unwinding occurred.

[0079]

[0080]

[0081] As is clear from the above examples, resin foam composites satisfying the requirements of the present invention suppressed odor generation and did not develop buckling wrinkles when unwound. Furthermore, because the surface smoothness was good and the surface layer was not brittle, no breakage or peeling occurred when the composites were attached to an adherend and then peeled off. In contrast, the resin foam composites produced in Comparative Examples 1, 3, and 4 did not have a surface layer containing inorganic particles, and therefore were unable to suppress odor generation. Furthermore, the resin foam composite produced in Comparative Example 2 had an average proportion of inorganic particle cross sections in the surface layer cross section exceeding 30%, resulting in impaired surface smoothness. Furthermore, because the surface layer was brittle, the composites were difficult to handle, resulting in breakage and peeling when attached to an adherend and then peeled off. Furthermore, the resin foam composites produced in Comparative Examples 3 and 4 did not contain inorganic particles in the surface layer portion and did not have a surface layer portion, so their tensile strength in the TD direction was low and wrinkles occurred at least when the resin foam composites were wound up or unwound.

[0082] 10, 10A, 10B, 10C: Resin foam composite 11, 11a, 11b: Foam layer 12, 12a, 12b, 20, 20': Surface layer

Claims

1. A resin foam composite product comprising a foam layer and a surface portion provided on at least one surface of the foam layer, wherein the surface portion contains inorganic particles, and the average proportion of cross-sections of the inorganic particles in cross-sections of the surface portion parallel to the thickness direction and TD direction of the resin foam composite product measured using an X-ray CT device is 30% or less.

2. The resin foam composite product according to claim 1, wherein the volume ratio of the inorganic particles to the total volume of the resin foam composite product is 0.02% or more.

3. A resin foam composite product according to claim 1 or 2, wherein the content of the inorganic particles is 0.01 parts by mass or more per 100 parts by mass of the resin foam composite product.

4. A resin foam composite product described in claim 1 or 2, wherein the resin foam composite product has a tensile strength in the MD direction of 1.0 MPa or more and a tensile strength in the TD direction of 0.6 MPa or more at 23°C.

5. A resin foam composite product as described in claim 1 or 2, wherein the arithmetic mean surface roughness Sa of the surface opposite to the foam layer side of the surface layer is 5 μm or more and 350 μm or less.

6. The resin foam composite article according to claim 1 or 2, wherein the inorganic particles are porous particles.