composite

Abstract

A composite according to the present invention comprises a resin foam layer and a non-foam layer which is laminated to at least one surface of the resin foam layer, wherein: the non-foam layer is provided with at least an inorganic-particle-containing layer that contains resin and inorganic particles; when a cross-section of the composite is measured via SEM-EDX, the amount of inorganic elements in the non-foam layer is not less than 0.01 at%; and the MD tensile elongation and / or TD tensile elongation of the composite at 160°C is not less than 80%.　The present invention makes it possible to provide a composite that comprises a resin foam layer and that has good vacuum molding properties.

Description

Complex

[0001] The present invention relates to a composite body including a resin foam layer and a non-foam layer.

[0002] Conventionally, foam sheets have been widely used in various fields because they can be easily manufactured into products with shapes suited to the intended purpose by 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, luxury, etc. Crosslinked olefin resin foam sheets, for example, are used as automotive interior materials.

[0003] For example, Patent Document 1 describes a crosslinked olefin resin foam comprising a composition containing 20 to 50% by weight of a polypropylene resin (A) having at least one endothermic peak of 160° C. or higher as measured by a differential scanning calorimeter, 20 to 50% by weight of a polypropylene resin (B) having an endothermic peak of less than 160° C., and 20 to 40% by weight of a polyethylene resin (C). It also describes that the crosslinked polyolefin resin foam has excellent heat resistance and good moldability at high temperatures, and is therefore suitable for use as an automotive interior material.

[0004] JP 2013-057070 A

[0005] Recently, there has been a demand for improved vacuum formability at high temperatures (e.g., about 150 to 300°C) from the viewpoint of improving productivity when processing foams into desired shapes. Therefore, an object of the present invention is to provide a composite including a resin foam layer, which has good vacuum formability.

[0006] The present inventors conducted extensive research to solve the above-mentioned problems. As a result, they found that the above-mentioned problems can be solved by a composite of a resin foam layer and a non-foam layer, in which the non-foam layer includes at least an inorganic particle-containing layer containing a resin and inorganic particles, the non-foam layer has a certain amount of inorganic elements or more, and at least one of an MD and a TD tensile elongation at 160°C is certain or more, and thus completed the present invention. That is, the present invention provides the following [1] to [6].

[0007] [1] A composite comprising a resin foam layer and a non-foam layer laminated on at least one surface of the resin foam layer, wherein the non-foam layer comprises at least an inorganic particle-containing layer containing a resin and inorganic particles, and wherein, when a cross section of the composite is measured by SEM-EDX, the amount of inorganic elements in the non-foam layer is 0.01 atomic % or more, and at least one of the MD tensile elongation and the TD tensile elongation of the composite at 160°C is 80% or more. [2] The composite according to [1] above, wherein, when a cross section of the composite is measured by SEM-EDX, the amount of at least one of Si and Al atoms in the non-foam layer is 0.01 atomic % or more. [3] The amount of inorganic residue when burned at 500°C is 0.05 g / m ２ The composite according to the above [1] or [2]. [4] The composite according to any one of the above [1] to [3], wherein the resin foam layer is a polyolefin resin foam. [5] The composite according to the above [4], wherein the polyolefin resin foam is a cross-linked polyolefin resin foam. [6] The composite according to any one of the above [1] to [5], wherein the resin contained in the non-foam layer is a polyolefin resin.

[0008] According to the present invention, it is possible to provide a composite having a resin foam layer and having good vacuum formability.

[0009] Fig. 1 is a cross-sectional view schematically showing one embodiment of the composite of the present invention. Fig. 2 is a cross-sectional view schematically showing another embodiment of the composite of the present invention. Fig. 3 is a cross-sectional view schematically showing another embodiment of the composite of the present invention.

[0010] The present invention will be described in detail below using embodiments. [Composite] The composite of the present invention is a composite comprising a resin foam layer and a non-foam layer laminated on at least one surface of the resin foam layer. The non-foam layer comprises at least an inorganic particle-containing layer containing a resin and inorganic particles, and when a cross section of the composite is measured by SEM-EDX, the amount of inorganic elements in the non-foam layer is 0.01 atomic % or more, and at least one of the MD tensile elongation and TD tensile elongation of the composite at 160°C is 80% or more.

[0011] The composite of the present invention will be described with reference to the drawings. Note that the present invention is not limited to the contents of the drawings. As shown in FIG. 1 , a composite 10 of the present invention includes a resin foam layer 11 and a non-foam layer 12 laminated on one side of the resin foam 11. The non-foam layer 12 is an inorganic particle-containing layer containing a resin and inorganic particles. While FIG. 1 shows a diagram in which the non-foam layer 12 is laminated on one side of the resin foam layer 11, the non-foam layer 12 may be laminated on both sides of the resin foam layer 11. From the viewpoint of improving vacuum formability and considering applications such as automotive interior materials, a composite in which the non-foam layer 12 is laminated on one side of the resin foam layer 11, as shown in FIG. 1 , is preferred.

[0012] Although the composite 10 in Fig. 1 shows an embodiment in which the resin foam has only one layer, the resin foam may have multiple layers of two or more layers. For example, the resin foam layer 11 may have a two-layer structure of a resin foam layer 11a and a resin foam layer 11b as shown in Fig. 2. The composite 10A in Fig. 2 is a composite in which the resin foam layer 11b, the resin foam layer 11a, and the non-foam layer 12 are laminated in this order.

[0013] While the composite 10 in FIG. 1 shows an embodiment in which the non-foam layer 12 consists of only one layer, the non-foam layer 12 may be multi-layered, i.e., two or more layers. For example, the non-foam layer 12 may be a two-layer structure consisting of a first non-foam layer 12b and a second non-foam layer 12a, as shown in FIG. 3. The composite 10B in FIG. 3 is a composite in which a resin foam layer 11, a first non-foam layer 12b, and a second non-foam layer 12a are laminated in this order. When the non-foam layer 12 is multi-layered, at least one layer of the multi-layer structure may be an inorganic particle-containing layer containing a resin and inorganic particles, and the other layers may or may not contain inorganic particles. For example, in FIG. 3, the second non-foam layer 12a may be a resin layer containing no inorganic particles, and the first non-foam layer 12b may be an inorganic particle-containing layer containing a resin and inorganic particles.

[0014] [Non-foam layer] The composite of the present invention has a non-foam layer laminated on at least one surface of the resin foam layer. The non-foam layer includes at least an inorganic particle-containing layer containing a resin and inorganic particles. Unlike the resin foam layer, the non-foam layer is a layer produced without being foamed during production.

[0015] (Amount of inorganic elements) When a cross section of the composite is measured by SEM-EDX, the amount of inorganic elements in the non-foam layer is 0.01 atomic % or more. When the amount of inorganic elements is 0.01 atomic % or more, the vacuum formability of the composite is improved. Although the reason for this is unclear, it is presumed that the dispersion of a certain amount or more of inorganic particles in the resin disperses stress and increases the elongation of the composite. From the viewpoint of improving the vacuum formability of the composite, the amount of inorganic elements in the non-foam layer is preferably 0.1 atomic % or more, more preferably 0.2 atomic % or more, and even more preferably 0.5 atomic % or more. The upper limit of the amount of inorganic elements in the non-foam layer is not particularly limited, but from the viewpoint of surface smoothness, the amount of inorganic elements is preferably 20 atomic % or less. The amount of inorganic elements is the total amount of inorganic elements confirmed by SEM-EDX measurement.

[0016] The type of inorganic element present in the non-foam layer is not limited, but examples include Si, Al, Mg, Ca, Na, K, Ti, V, Cr, Mn, Fe, Mo, Co, Cu, Zn, Ga, Zr, Pd, Pt, Ba, Pb, Ag, Sn, W, and Au, with at least one of Si and Al being preferred. The inclusion of either Si or Al as an inorganic element in the non-foam layer further improves the vacuum formability of the composite. This is thought to be due to the enhanced stress dispersion effect through the interaction of Si and Al with the resin. From the perspective of improving the vacuum formability of the composite, when a cross section of the composite is measured by SEM-EDX, the amount of at least one of Si and Al atoms in the non-foam layer is preferably 0.01 atomic % or more, more preferably 0.1 atomic % or more.

[0017] The amount of inorganic elements in the non-foam layer is measured by SEM-EDX. SEM-EDX is an energy dispersive X-ray analyzer (EDX) attached to a scanning electron microscope (SEM). It is an instrument capable of performing elemental analysis of a field of view while observing the morphology with the SEM. The type and amount of elements are identified from the X-rays generated by irradiating a sample with an electron beam. The amount of inorganic elements in the non-foam layer is measured by SEM-EDX measurement, where the average thickness from the interface between the resin foam and the non-foam layer to the outermost surface of the non-foam layer is measured, and the amount of inorganic elements in the layer having that average thickness is measured. The average thickness can be determined by measuring the thickness at 10 evenly spaced points and averaging these measurements. For example, the area from the interface between the resin foam and the non-foam layer to the outermost surface of the non-foam layer corresponds to the region a in FIG. 1 if the non-foam layer is a single layer, or the region a' in FIG. 3 if the non-foam layer is a multilayer.

[0018] (Composition of Non-Foam Layer) The non-foam layer contains a resin and inorganic particles. As described above, the non-foam layer may be a single layer or a multilayer, and includes at least an inorganic particle-containing layer containing a resin and inorganic particles. That is, the non-foam layer may be composed only of an inorganic particle-containing layer containing a resin and inorganic particles, or may include the inorganic particle-containing layer and a resin layer that does not contain inorganic particles. Whether or not the non-foam layer contains inorganic particles can be determined by morphological observation using SEM-EDX as described above.

[0019] (Resin) The resin contained in the inorganic particle-containing layer is not particularly limited, but is preferably a thermoplastic resin. Examples of the thermoplastic resin include thermoplastic elastomers such as olefin thermoplastic elastomer (TPO), styrene thermoplastic elastomer, ester thermoplastic elastomer, and amide thermoplastic elastomer, polyolefin resins such as polypropylene resin (PP), polyethylene resin (PE), and poly(1-)butene resin, acrylonitrile-butadiene-styrene (ABS) resin, polycarbonate resin, polyphenylene ether resin, (meth)acrylic resin, polyamide resin, and polyvinyl chloride resin (PVC).

[0020] Among these, the thermoplastic resin is preferably at least one selected from polyolefin-based resins and olefin-based thermoplastic elastomers (TPOs), more preferably polyolefin-based resins, and even more preferably polyethylene-based resins. The use of these resins tends to improve the vacuum formability of the composite. Furthermore, when the resin foam layer described below is a polyolefin resin foam, the resin in the inorganic particle-containing layer is preferably a polyethylene-based resin. This improves the adhesion between the resin foam layer and the non-foam layer, and also improves the vacuum formability.

[0021] As the olefin-based thermoplastic elastomer (TPO), any of blend type, dynamically crosslinked type, and polymerization type can be used. Specific examples of olefin-based thermoplastic elastomers include those containing polypropylene as a hard segment and a copolymer containing ethylene, propylene, and optionally a small amount of a diene component as a soft segment. Examples of such copolymers include ethylene-propylene copolymer (EPR) and ethylene-propylene-diene copolymer (EPDM). Other specific examples of olefin-based thermoplastic elastomers (TPO) include a blend of polyethylene and EPR, a blend of polyethylene and EPR partially crosslinked using an organic peroxide, a blend of polyethylene and EPR graft-modified with an unsaturated hydroxy monomer, an unsaturated carboxylic acid derivative, or the like, and butyl-grafted polyethylene.

[0022] 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.

[0023] (Inorganic Particles) The inorganic particle-containing layer contains inorganic particles. Examples of inorganic particles include, but are not limited to, fumed silica, mesoporous silica, silica gel, talc, layered double hydroxide, synthetic zeolite, naturally occurring zeolite, activated carbon, smectite, montmorillonite, diatomite, clinker ash, fly ash, hydrotalcite, dolomite, calcium carbonate, aluminum oxide, magnesium oxide, calcium oxide, strontium oxide, barium oxide, zirconium oxide, aluminum hydroxide, magnesium silicate, magnesium hydroxide, strontium hydroxide, barium hydroxide, zirconium hydroxide, zirconium phosphate, titanium phosphate, and aluminum phosphate. These particles may be used alone or in combination of two or more. Particles in which the above-listed compounds are layered, core-shell particles, hollow particles, agglomerated particles, or fused alloys synthesized using the above-listed substances as templates may also be used. The above-listed inorganic particles may be porous or non-porous, with porous particles being preferred.

[0024] Among the inorganic particles described above, from the viewpoint of improving the vacuum formability of the composite, the inorganic particles are preferably one or more types selected from the group consisting of silica gel, magnesium oxide, aluminum oxide, aluminum hydroxide, calcium carbonate, and zeolite, and more preferably one or more types selected from the group consisting of silica gel, aluminum oxide, aluminum hydroxide, mesoporous silica, and zeolite.

[0025] The inorganic substance is preferably in the form of particles, and the average particle size thereof is not particularly limited, but is preferably 0.01 to 100 μm, more preferably 0.1 to 80 μm, and even more preferably 0.5 to 20 μm. The average particle size of the inorganic substance means the cumulative median diameter measured using a particle size distribution diameter measuring instrument, SEM measurement, or the like.

[0026] The content of the inorganic substance in the inorganic particle-containing layer is not particularly limited, but is preferably 10 to 300 parts by mass, and more preferably 100 to 150 parts by mass, per 100 parts by mass of the resin.

[0027] The thickness of the inorganic particle-containing layer is not particularly limited, but from the viewpoint of improving the vacuum formability of the composite, it is preferably 1 to 200 μm, more preferably 3 to 100 μm, and even more preferably 5 to 50 μm.

[0028] The inorganic particle-containing layer is preferably a coating film, more specifically, a coating film formed from an inorganic particle-containing aqueous emulsion described below. When the inorganic particle-containing layer is a coating film, odor generation can be reduced.

[0029] As described above, the non-foam layer may include a resin layer (second non-foam layer) that does not contain inorganic particles. When the composite includes a resin layer that does not contain inorganic particles, the surface smoothness is more easily improved. The resin layer is a layer composed of a resin alone or a resin and other additives such as an antioxidant. The resin contained in the resin layer can be any of the resins described above for the inorganic particle-containing layer, without any particular restrictions. Among these, polyethylene-based resins or olefin-based thermoplastic elastomers (TPOs) are preferred, with olefin-based thermoplastic elastomers (TPOs) being more preferred.

[0030] The thickness of the resin layer (second non-foam layer) that does not contain inorganic particles is not particularly limited, but is preferably 100 to 1000 μm, and more preferably 300 to 700 μm.

[0031] The thickness of the non-foam layer (the total thickness of the non-foam layer) is not particularly limited, but is, for example, 1 to 1000 μm, preferably 5 to 600 μm, from the viewpoint of improving the vacuum formability of the composite. When the non-foam layer consists only of an inorganic particle-containing layer containing resin and inorganic particles, the thickness of the non-foam layer is the thickness of the inorganic particle-containing layer. When the non-foam layer comprises both an inorganic particle-containing layer and a resin layer that does not contain inorganic particles, the thickness of the non-foam layer is the total thickness of the inorganic particle-containing layer and the resin layer.

[0032] [Resin Foam Layer] The composite of the present invention includes a resin foam layer. The inclusion of a resin foam layer can impart flexibility, lightness, and the like to the composite. The resin foam layer is not particularly limited, and examples thereof 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. The resin foam layer can use one of these foams alone or in combination of two or more. Among these foams, polyolefin resin foam is preferred for the resin foam layer, and crosslinked polyolefin resin foam is more preferred.

[0033] The resin foam layer is formed by foaming a foamable resin composition containing a resin. When the resin foam layer is a crosslinked polyolefin resin foam, the resin foam layer is formed by crosslinking and foaming a foamable resin composition containing a polyolefin resin.

[0034] (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.

[0035] 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. Incidentally, "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 the total monomer-derived structural units. The same applies below. 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 typically 0.1 g / 10 min. The MFR of the polypropylene resin 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.

[0036] 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 of the polyethylene resin 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.

[0037] When the polyolefin resin contains a polypropylene-based resin, the foamable resin composition 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 relative to the total amount of resin contained in the foamable resin composition 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 in the non-foam layer section. The foamable resin composition may also contain a resin other than a polyolefin resin and an olefin-based elastomer.

[0038] <Antioxidant> The foamable resin composition preferably contains an antioxidant. The inclusion of an antioxidant can suppress oxidative degradation of the polyolefin resin and reduce the odor of the crosslinked polyolefin resin foam. The foamable resin composition preferably contains 0.1 to 5.0 parts by mass, and more preferably 1.0 to 4.0 parts by mass, of the antioxidant per 100 parts by mass of the resin. By using 0.5 parts by mass or more of the antioxidant per 100 parts by mass of the resin, oxidative degradation of the polyolefin resin can be further suppressed and the odor of the crosslinked polyolefin resin foam can be reduced. Furthermore, by using 5.0 parts by mass or less of the antioxidant per 100 parts by mass of the resin, the conversion of excess antioxidant into an odorous substance can be prevented.

[0039] 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, 2,6-di-tert-butyl-p-cresol is preferred. The antioxidants may be used alone or in combination of two or more.

[0040] <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 the resin contained in the foamable resin composition. By using 2.0 parts by mass or more of the crosslinking auxiliary agent per 100 parts by mass of the resin, heat resistance can be improved and odor generation of the foam can be reduced. This is thought to be because the crosslinking of the polyolefin resin progresses to a certain extent, suppressing deterioration due to heat, etc., and as a result, suppressing 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 the resin, vacuum moldability is improved and poor foaming can be easily prevented.

[0041] 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 in one molecule include trimellitic acid triallyl ester, 1,2,4-benzenetricarboxylic acid triallyl ester, and triallyl isocyanurate. The crosslinking aids can be used alone or in combination of two or more. Among these, polyfunctional (meth)acrylate compounds are preferred, bifunctional (meth)acrylate compounds are more preferred, and 1,9-nonanediol dimethacrylate is even more preferred.

[0042] <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 ammonium carbonate, ammonium hydrogencarbonate, azodicarbonamide, ammonium nitrite, and azobisisobutyronitrile; nitroso compounds such as N,N'-dinitrosopentamethylenetetramine; hydrazine derivatives such as hydrazodicarbonamide, 4,4'-oxybis(benzenesulfonylhydrazide), and toluenesulfonylhydrazide; guanidine salts such as guanidine phosphate, guanidine bicarbonate, guanidine hydrochloride, and guanidine sulfate; and semicarbazide compounds such as toluenesulfonylsemicarbazide.

[0043] Examples of inorganic foaming agents include metal azodicarboxylates (e.g., barium azodicarboxylate), 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 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 polyolefin resin, from the viewpoint of easily adjusting the expansion ratio of the foam to the range described below.

[0044] <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.

[0045] <Expansion Ratio> The expansion ratio of the resin foam layer 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. On the other hand, 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 foamable resin composition before expansion to the resin foam layer after expansion. ３ / g) was measured, and the specific volume of the resin foam layer was calculated by dividing the specific volume of the foamable resin composition before foaming.

[0046] <Degree of Crosslinking> The degree of crosslinking of the resin foam layer of the present invention is preferably 30 to 60% by mass. A degree of crosslinking of 30 to 60% by mass allows for a well-balanced improvement in the mechanical strength, flexibility, and vacuum formability of the foam. From the viewpoint of a well-balanced improvement in the mechanical strength, flexibility, and vacuum formability of the foam, the degree of crosslinking of the crosslinked polyolefin resin foam of the present invention is more preferably 33 to 57% 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 is taken from the resin foam layer, and the mass A (mg) of the test piece is precisely weighed. Next, this test piece is immersed in 30 cm of xylene at 120°C. ３ After immersion for 24 hours, the insoluble matter on the mesh is filtered through a 200-mesh wire netting, vacuum-dried, and the mass B (mg) of the insoluble matter is precisely weighed. The degree of crosslinking (mass%) is calculated from the obtained value using the following formula: Degree of crosslinking (mass%) = 100 × (B / A).

[0047] <Thickness> The thickness of the resin foam layer 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] [Composite] The composite of the present invention comprises the above-described resin foam layer and a non-foam layer. The composite will be described below.

[0049] <Thickness Ratio> In the composite, the ratio of the thickness of the resin foam layer to the thickness of the non-foam layer (resin foam layer / non-foam layer) is not particularly limited, but is preferably 1 to 500, and more preferably 2 to 300. In the non-foam layer, the ratio of the thickness of the resin foam layer to the thickness of the inorganic particle-containing layer (resin foam layer / inorganic particle-containing layer) is not particularly limited, but is preferably 100 to 500, and more preferably 200 to 300. By setting the thickness ratio within the above range, the vacuum formability of the composite is likely to be good.

[0050] <Tensile elongation> At least one of the MD tensile elongation and TD tensile elongation of the composite of the present invention at 160°C is 80% or more. This improves vacuum formability at high temperatures. At least one of the MD tensile elongation and TD tensile elongation of the composite at 160°C is preferably 90% or more, more preferably 100% or more, and even more preferably 140% or more. Furthermore, both of the MD tensile elongation and TD tensile elongation of the composite at 160°C are preferably 80% or more, more preferably 90% or more, even more preferably 100% or more, and even more preferably 140% or more. The upper limit of the tensile elongation is not particularly limited, but is, for example, 500%. Note that "MD" refers to machine direction and refers to a direction that coincides with the extrusion direction of the resin foam layer. Furthermore, "TD" refers to transverse direction and refers to a direction perpendicular to the MD and parallel to the resin foam layer. The tensile elongation can be adjusted to a desired value by adjusting the composition, thickness, etc. of the resin foam layer and the non-foam layer. The tensile elongation (tensile stretch) can be measured in accordance with JIS K6767.

[0051] <Amount of inorganic residue> The amount of inorganic residue when the composite is burned at 500°C is preferably 0.05 g / m ２ The amount of inorganic residue is 0.05 g / m or more. ２ When the amount of inorganic residue is 0.1 g / m or more, it becomes easy to adjust the tensile elongation to the above range, and the vacuum formability at high temperatures is improved.２ More preferably, it is 0.5 g / m or more. ２ Although there is no particular upper limit to the amount of inorganic residue, from the viewpoint of the surface smoothness of the composite, the amount of inorganic residue is preferably 5 g / m ２ The amount of inorganic residue is determined based on the unit area (m ２ ) and is calculated from the amount of residue when the composite is burned in air at 500°C for 240 minutes.

[0052] [Method for manufacturing composite] The method for manufacturing the composite of the present invention is not particularly limited, but examples include a method comprising a step (A) of manufacturing a resin foam layer and a step (B) of forming a non-foam layer on at least one surface of the resin foam layer manufactured in the step (A).

[0053] <Step (A)> Step (A) is a step of producing a resin foam layer. Step (A) is preferably produced by a method including, for example, the following steps 1 to 3: (Step 1) a step of processing a foamable resin composition into a sheet to produce a foamable sheet; (Step 2) a step of irradiating the foamable sheet with ionizing radiation to produce a cross-linked foamable sheet; and (Step 3) a step of foaming the cross-linked foamable sheet to produce a resin foam layer.

[0054] (Step 1) Step 1 is a step of processing the foamable resin composition into a sheet to produce a foamable sheet. The foamable resin composition is kneaded using a kneader such as a Banbury mixer or a pressure kneader, and then continuously extruded using an extruder, a calender, conveyor belt casting, or the like to produce a foamable sheet. The temperature at which the foamable resin composition is kneaded is preferably 170 to 210°C, and more preferably 175 to 205°C.

[0055] (Step 2) Step 2 is a step of irradiating the foamable sheet with ionizing radiation to produce a crosslinked foamable sheet. When the resin foam layer is a crosslinked polyolefin resin foam, the irradiation dose when irradiating with ionizing radiation is preferably 1 to 10 Mrad, more preferably 1.5 to 5 Mrad. Irradiation with ionizing radiation may be performed on one side or both sides of the foamable sheet. Examples of ionizing radiation include electron beams, α-rays, β-rays, γ-rays, and X-rays. Of these, electron beams are preferred from the viewpoints of productivity and uniform irradiation.

[0056] (Step 3) Step 3 is a step of foaming the cross-linked foamable sheet to produce a sheet-like resin foam layer. Examples of methods for foaming the cross-linked foamable sheet include a batch method using an oven and a continuous foaming method in which the cross-linked foamable sheet is continuously passed through a heating furnace. When the resin foam layer is a cross-linked polyolefin resin foam, the temperature during foaming of the cross-linked foamable sheet is approximately 150 to 320°C. The method for adjusting the temperature to the above range is not particularly limited, and may include the use of hot air or infrared light having a near-infrared wavelength region, a far-infrared wavelength region, or both. Furthermore, after foaming or during foaming, the cross-linked foamable sheet may be stretched in either the MD direction or the TD direction, or both.

[0057] <Step (B)> Step (B) is a step of forming a non-foam layer on at least one surface of the resin foam layer produced in step (A). A method of forming a non-foam layer on at least one surface of the resin foam layer includes a method using an aqueous emulsion for forming an inorganic particle-containing layer in the non-foam layer. For example, a non-foam layer can be formed on at least one surface of the resin foam layer through the following steps 4 to 6: (Step 4) A step of preparing an aqueous emulsion; (Step 5) A step of dispersing inorganic particles in the aqueous emulsion to prepare an inorganic particle-containing aqueous emulsion; and (Step 6) A step of applying the inorganic particle-containing aqueous emulsion to at least one surface of the resin foam layer and drying it to form an inorganic particle-containing layer.

[0058] (Step 4) Step 4 is a step of preparing an aqueous emulsion. The aqueous emulsion contains at least water and resin particles. The resin particles are of the same type as the resin contained in the inorganic particle-containing layer to be formed. That is, when the resin contained in the inorganic particle-containing layer is a polyethylene-based resin, the resin particles contained in the aqueous emulsion are polyethylene-based resin particles.

[0059] The aqueous emulsion is preferably obtained by emulsion polymerization of a monomer for producing resin particles. In the case where the resin particles are, for example, a polyethylene-based resin, the monomer for producing the resin particles is, for example, an ethylene monomer, and, optionally, an α-olefin monomer having approximately 3 to 10 carbon atoms. Specifically, the aqueous emulsion can be produced by adding a surfactant as an emulsifier and a monomer to a dispersion medium containing water as the main component (for example, a dispersion medium containing 90% by mass or more of water, preferably a dispersion medium consisting of water), and emulsion-polymerizing the monomer while stirring. In emulsion polymerization, additives such as a polymerization initiator, a chain transfer agent, and a stabilizer may be blended as necessary.

[0060] (Step 5) In step 5, inorganic particles are dispersed in the aqueous emulsion prepared as described above to form an inorganic particle-containing aqueous emulsion. The inorganic particles dispersed in the aqueous emulsion are of the same type as the inorganic particles contained in the inorganic particle-containing layer to be formed. The amount of inorganic particles in the inorganic particle-containing aqueous emulsion per 100 parts by mass of resin particles is the same as the amount of inorganic particles per 100 parts by mass of resin in the inorganic particle-containing layer described above.

[0061] (Step 6) In step 6, the inorganic particle-containing aqueous emulsion obtained as described above is applied to at least one surface of the resin foam layer and dried to form an inorganic particle-containing layer. The method for applying the inorganic particle-containing aqueous emulsion is not particularly limited, and various coaters may be used. For example, application can be performed using a bar coater, comma coater, dip coater, roll coater, spin coater, flow coater, knife coater, spray coater, or the like. The temperature during drying is, for example, 40 to 160°C, and preferably 60 to 130°C.

[0062] By performing the above steps 4 to 6, a composite is obtained consisting of a resin foam layer and a non-foam layer laminated on at least one surface of the resin foam layer. In this case, the non-foam layer is composed of a single layer of inorganic particle-containing layer, which is a coating film of an inorganic particle-containing aqueous emulsion. While the above method is a method for forming a composite using an aqueous emulsion, the method for forming the non-foam layer is not limited to methods using an aqueous emulsion. For example, the inorganic particle-containing layer that constitutes the non-foam layer may be separately prepared by extrusion molding or the like, and the inorganic particle-containing layer may be laminated on at least one surface of the resin foam layer to form a composite. Among the above methods, the method using an aqueous emulsion is preferred because it reduces the odor of the resulting composite.

[0063] In the above steps 4 to 6, the method for forming the inorganic particle-containing layer is described by describing a "step of preparing an aqueous emulsion" and a "step of preparing an inorganic particle-containing aqueous emulsion." However, commercially available products can be used as the "aqueous emulsion" and the "inorganic particle-containing aqueous emulsion" as needed.

[0064] When the non-foam layer is made multi-layered, for example, a resin layer (such as a resin film) that does not contain inorganic particles may be laminated on the surface of the inorganic particle-containing layer formed on at least one side of the resin foam layer as described above.

[0065] The lamination method and process are not particularly limited, but may be a method of applying heat and pressure using a press, a radiant heat heater, near infrared rays, far infrared rays, etc. to achieve thermocompression bonding, or a method using an adhesive or pressure-sensitive adhesive.

[0066] <Uses> The composite of the present invention can be molded by various molding methods such as vacuum molding and used as a heat insulating material, cushioning material, etc. In particular, in the automotive field, the composite of the present invention can be suitably used as an automotive interior material such as a ceiling material, a door, or an instrument panel.

[0067] The present invention will be explained in more detail by way of examples, but the present invention is not limited to these examples in any way.

[0068] [Measurement Methods] The methods for measuring and evaluating each physical property are as follows.

[0069] <Amount (atomic %) of inorganic elements in non-foam layer> A cross section of the composite was measured using a SEM-EDX device ("JSM-IT100" manufactured by JEOL Ltd.) to measure the amount (atomic %) of inorganic elements in the non-foam layer. The measurement conditions for SEM-EDX were as follows: visual field magnification: 2000x, observation field angle: 125.0 × 95.0 μm, applied voltage: 10 kV, WD: 10 mm. In addition, the presence or absence of Si atoms or Al atoms in the non-foam layer was confirmed, and the amount (atomic %) of these atoms in the non-foam layer was measured.

[0070] <Tensile elongation> The tensile elongation at 160°C in the MD direction of the composite was measured in accordance with JIS K6767. Next, the tensile elongation at 160°C in the TD direction of the composite was measured in accordance with JIS K6767.

[0071] <Amount of inorganic residue after burning at 500°C> The composite was used as a sample and burned in air at 500°C for 240 minutes, and the amount of inorganic residue was measured. The amount of inorganic residue was measured per unit area (m ２ ) means the amount of inorganic residue per unit area.

[0072] <Expansion Ratio and Crosslinking Degree of Resin Foam Layer> The expansion ratio and crosslinking degree of the resin foam layer were measured by the methods described in the specification.

[0073] <Evaluation of high-temperature vacuum formability> The composites produced in each example and comparative example were evaluated for vacuum formability by setting the forming mold temperature at 300-400°C and measuring the curved cup forming drawing ratio (cup height / cup diameter = 0.68-0.98) under conditions where the test piece temperature was 160°C. Vacuum formability was evaluated according to the following criteria. The experiment was carried out by gradually increasing the drawing ratio (cup height / cup diameter), and vacuum forming was carried out for each piece. The formability was evaluated by the drawing ratio (cup height / cup diameter) at which the composite broke or a thin, transparent portion appeared in part of the composite. (Evaluation criteria) A 0.92 or more B 0.86-0.90 C 0.80-0.84 D 0.78 or less

[0074] [Components Used] The components used in each Example and Comparative Example are as follows. (Raw Materials for Resin 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: olefin-based elastomer, manufactured by Mitsui Chemicals, Inc., trade name "3045" Foaming agent: azodicarbonamide, manufactured by Otsuka Chemical Co., Ltd., trade name "SO-L", decomposition temperature: 197°C, average particle size: 3.2 μm Phenol-based antioxidant: manufactured by BASF Japan Ltd., 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

[0075] (Raw materials for non-foam layer) Inorganic particle-containing aqueous emulsion (1) - A water-based emulsion in which polyethylene resin particles are dispersed, and silica gel (SiO ２ ) was dispersed to prepare an inorganic particle-containing aqueous emulsion (1). ２ The amount of silica gel (SiO ２ ) has an average particle size of 1 μm.

[0076] Inorganic particle-containing aqueous emulsion (2): Magnesium oxide (MgO) was dispersed in an aqueous emulsion in which polyethylene resin particles were dispersed to prepare an inorganic particle-containing aqueous emulsion (2). The amount of magnesium oxide (MgO) per 100 parts by mass of polyethylene resin particles in the inorganic particle-containing aqueous emulsion (2) was 10 parts by mass. The average particle diameter of the magnesium oxide (MgO) used was 8 μm.

[0077] Inorganic particle-containing aqueous emulsion (3) ... A water-based emulsion in which polyethylene resin particles are dispersed, and aluminum hydroxide (Al(OH) ３ ) was dispersed to prepare an inorganic particle-containing aqueous emulsion (3). The ratio of aluminum hydroxide (Al(OH)) to 100 parts by mass of polyethylene resin particles in the inorganic particle-containing aqueous emulsion (3) was ３ The amount of aluminum hydroxide (Al(OH) ３ ) has an average particle size of 5 μm.

[0078] Inorganic particle-containing aqueous emulsion (4) ... A water-based emulsion in which polyethylene resin particles are dispersed, and aluminum oxide (Al ２ O ３ ) was dispersed to prepare an inorganic particle-containing aqueous emulsion (4). ２ O ３ The amount of aluminum oxide (Al) used was 65 parts by mass. ２ O ３ ) has an average particle size of 3 μm.

[0079] Inorganic particle-containing aqueous emulsion (5) ... A water-based emulsion in which polyethylene resin particles are dispersed, calcium carbonate (CaCO ３ ) was dispersed to prepare an inorganic particle-containing aqueous emulsion (5). ３ The amount of calcium carbonate (CaCO ３ ) has an average particle size of 7 μm.

[0080] Inorganic particle-containing aqueous emulsion (6): Zeolite was dispersed in an aqueous emulsion in which polyethylene resin particles were dispersed, to prepare an inorganic particle-containing aqueous emulsion (6). The amount of zeolite per 100 parts by mass of polyethylene resin particles in the inorganic particle-containing aqueous emulsion (6) was 110 parts by mass. The average particle size of the zeolite used was 4 μm.

[0081] Resin film: A 500 μm thick resin film formed from TPO. The TPO used was an olefin-based thermoplastic elastomer manufactured by Basell, trade name "Softell CA 02 A," with an MFR of 0.6 g / 10 min (230° C.).

[0082] Example 1 (Production of Resin Foam Layer) A foamable resin composition obtained by mixing polypropylene-based resin (2), LLDPE, a phenol-based antioxidant, a crosslinking aid, and a foaming agent according to the formulation shown in Table 1 was melt-kneaded at 180°C using a single-screw extruder to form a foamable sheet. Both sides of the foamable sheet were irradiated with ionizing radiation (electron beam) at an acceleration voltage of 1000 keV and 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, where it was heated and foamed while being stretched to obtain a crosslinked polyolefin resin foam having a thickness of 2.5 mm. (Production of Composite) One side of the crosslinked polyolefin resin foam prepared as described above was coated with inorganic particle-containing aqueous emulsion (1) using a roll coater, and then dried at a drying temperature of 100°C to form a non-foam layer consisting of an inorganic particle-containing layer. In this manner, a composite of crosslinked polyolefin resin foam / inorganic particle-containing layer (non-foam layer) was obtained.

[0083] [Examples 2 to 7, 9] Crosslinked polyolefin resin foams were obtained in the same manner as in Example 1, except that the formulation of the foamable resin composition was changed as shown in Table 1. Then, composites were obtained in the same manner as in Example 1, using the following types of inorganic particle-containing aqueous emulsions. In Example 2, inorganic particle-containing aqueous emulsion (2), in Example 3, inorganic particle-containing aqueous emulsion (3), in Examples 4 and 9, inorganic particle-containing aqueous emulsion (4), in Example 5, inorganic particle-containing aqueous emulsion (5), and in Examples 6 and 7, inorganic particle-containing aqueous emulsion (6).

[0084] Example 8 A crosslinked polyolefin resin foam was obtained in the same manner as in Example 1, except that the composition of the foamable resin composition was changed as shown in Table 1. An inorganic particle-containing aqueous emulsion (6) was applied to one side of the obtained crosslinked polyolefin resin foam using a roll coater, and then dried at a drying temperature of 100°C to form a non-foam layer (first non-foam layer) composed of an inorganic particle-containing layer. Next, a 500 μm-thick resin film formed using TPO was thermally laminated onto the surface of the inorganic particle-containing layer to form a second non-foam layer. In this manner, a composite was obtained in which the crosslinked polyolefin resin foam / inorganic particle-containing layer (first non-foam layer) / resin film (second non-foam layer) were laminated in this order. The inorganic particle-containing layer and the resin film constituted the non-foam layer.

[0085] Comparative Example 1 A crosslinked polyolefin resin foam was obtained in the same manner as in Example 1. Next, an aluminum foil having a thickness of 10 μm was attached to one side of the crosslinked polyolefin by thermal lamination.

[0086] Comparative Example 2 A crosslinked polyolefin resin foam was obtained in the same manner as in Example 1. Next, an aqueous emulsion (containing no inorganic particles) in which polyethylene resin particles were dispersed was applied to one side of the crosslinked polyolefin resin foam using a roll coater, and then dried at a drying temperature of 100° C. to form a polyethylene resin layer on the foam. The polyethylene resin layer was a non-foam layer containing no inorganic particles.

[0087] Comparative Example 3 A crosslinked polyolefin resin foam was obtained in the same manner as in Example 1, except that the composition of the foamable resin composition was changed as shown in Table 1. Next, an aqueous emulsion (containing no inorganic particles) in which polyethylene resin particles were dispersed was applied to one side of the crosslinked polyolefin resin foam using a roll coater, and then dried at a drying temperature of 100°C to form a polyethylene resin layer on the foam. Next, a 500 μm-thick resin film formed from TPO was thermally laminated onto the surface of the polyethylene resin layer. In this manner, a composite was obtained in which crosslinked polyolefin resin foam / polyethylene resin layer / resin film (TPO) were laminated in this order. The polyethylene resin layer and resin film were non-foam layers (containing no inorganic particles).

[0088]

[0089] The composites of Examples 1 to 9 each have a non-foam layer on one side of a resin foam layer, and the non-foam layer includes an inorganic particle-containing layer containing resin and inorganic particles. When the cross section of the composite is measured using SEM-EDX, the amount of inorganic elements in the non-foam layer is 0.01 atomic % or more, and the MD tensile elongation and TD tensile elongation at 160°C are 80% or more. The composites of Examples 1 to 9, which satisfy these requirements of the present invention, exhibited excellent high-temperature vacuum formability. In contrast, the composite of Comparative Example 1, which had low MD tensile elongation and TD tensile elongation at 160°C, and the composites of Comparative Examples 2 and 3, which did not contain inorganic particles in the non-foam layer, exhibited poor high-temperature vacuum formability.

[0090] 10, 10A, 10B Composite 11, 11a, 11b Resin foam layer 12 Non-foam layer 12a Second non-foam layer 12b First non-foam layer

Claims

1. A composite comprising a resin foam layer and a non-foam layer laminated on at least one surface of the resin foam layer, wherein the non-foam layer comprises at least an inorganic particle-containing layer containing a resin and inorganic particles, and when a cross section of the composite is measured by SEM-EDX, the amount of inorganic elements in the non-foam layer is 0.01 atomic % or more, and at least one of an MD tensile elongation and a TD tensile elongation of the composite at 160°C is 80% or more.

2. The composite according to claim 1, wherein the amount of at least one of Si and Al atoms in the non-foam layer is 0.01 atomic % or more when a cross section of the composite is measured by SEM-EDX.

3. The amount of inorganic residue when burned at 500°C is 0.05 g / m ２ The complex according to claim 1 or 2, wherein 4. The composite according to claim 1 or 2, wherein the resin foam layer is a polyolefin resin foam.

5. The composite of claim 4, wherein the polyolefin resin foam is a crosslinked polyolefin resin foam.

6. The composite according to claim 1 or 2, wherein the resin contained in the non-foam layer is a polyolefin resin.

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