complex

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

[Technical Field]

[0001] The present invention relates to a composite comprising a resin foam layer and a non-foam layer. [Background technology]

[0002] Traditionally, foam sheets have been widely used in various fields because they can be easily manufactured into products of a shape that suits the purpose 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 aesthetics, feel, and a sense of luxury. For example, cross-linked olefin resin foam sheets are used as interior materials in automobiles.

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

[0004] [Patent Document 1] Japanese Patent Publication No. 2013-057070 [Overview of the Initiative] [Problems that the invention aims to solve]

[0005] Incidentally, in recent years, there has been a demand for improved vacuum formability at high temperatures (for example, around 150-300°C) from the perspective of increasing productivity when processing foams into desired shapes. Therefore, the object of the present invention is to provide a composite comprising a resin foam layer, which has good vacuum moldability. [Means for solving the problem]

[0006] The inventors diligently studied to solve the above problems. As a result, they found that the above problems can be solved by a composite of a resin foam layer and a non-foam layer, wherein the non-foam layer comprises at least an inorganic particle-containing layer containing resin and inorganic particles, the amount of inorganic elements in the non-foam layer is above a certain level, and at least one of the MD and TD tensile elongations at 160°C is above a certain level. Based on this, the inventors completed the present invention described below. In other words, 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 resin and inorganic particles, the amount of inorganic elements in the non-foam layer is 0.01 atomic percent or more when the cross-section of the composite is measured by SEM-EDX, and at least one of the MD tensile elongation and TD tensile elongation of the composite at 160°C is 80% or more. [2] The composite according to [1], wherein the amount of at least one of Si and Al atoms in the non-foamed layer is 0.01 atomic percent or more when the cross-section of the composite is measured by SEM-EDX. [3] The amount of inorganic residue when burned at 500°C was 0.05 g / m³ 2 The above-mentioned complex as described in [1] or [2]. [4] The composite according to any one of [1] to [3] above, wherein the resin foam layer is a polyolefin resin foam. [5] The composite according to [4] above, wherein the polyolefin resin foam is a crosslinked polyolefin resin foam. [6] The composite according to any one of [1] to [5] above, wherein the resin contained in the non-foamed layer is a polyolefin resin. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a composite comprising a resin foam layer, which exhibits good vacuum moldability. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic cross-sectional view showing one embodiment of the composite of the present invention. [Figure 2] This is a schematic cross-sectional view illustrating another embodiment of the composite of the present invention. [Figure 3] This is a schematic cross-sectional view illustrating another embodiment of the composite of the present invention. [Modes for carrying out the invention]

[0010] The present invention will be described in detail below using embodiments. [complex] The composite of the present invention is a composite of 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 resin and inorganic particles, and when the cross-section of the composite is measured by SEM-EDX, the amount of inorganic elements in the non-foam layer is 0.01 atomic percent 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. However, the present invention is not limited in any way to what is shown in the drawings. As shown in Figure 1, the composite 10 of the present invention comprises a resin foam layer 11 and a non-foamed layer 12 laminated on one side of the resin foam 11. The non-foamed layer 12 is an inorganic particle-containing layer containing resin and inorganic particles. Figure 1 shows a diagram in which a non-foamed layer 12 is laminated on one side of a foamed resin layer 11, but the non-foamed layer 12 may be laminated on both sides of the foamed resin layer 11. From the viewpoint of improving vacuum formability and considering applications such as automotive interior materials, a composite in which the non-foamed layer 12 is laminated on one side of the foamed resin layer 11, as shown in Figure 1, is preferable.

[0012] In the composite 10 of FIG. 1, although the mode in which the resin foam consists of only one layer is shown, the resin foam may be a multilayer 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 of FIG. 2 is a composite in which a resin foam layer 11b, a resin foam layer 11a, and a non-foam layer 12 are laminated in this order.

[0013] In the composite 10 of FIG. 1, although the mode in which the non-foam layer 12 consists of only one layer is shown, the non-foam layer 12 may be a multilayer of two or more layers. For example, the non-foam layer 12 may have a two-layer structure of a first non-foam layer 12b and a second non-foam layer 12a as shown in FIG. 3. The composite 10B of 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 a multilayer, at least one layer of the multilayer is 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. Further, the non-foam layer is a layer produced without foaming during its production, unlike the resin foam layer.

[0015] (Amount of inorganic element) When the 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 the inorganic elements is 0.01 atomic % or more, the vacuum formability of the composite is improved. Although the reason for this is not clear, it is presumed that since a certain amount or more of inorganic particles are dispersed in the resin, stress is dispersed and the elongation of the composite increases. From the viewpoint of improving the vacuum formability of the composite, the amount of inorganic elements in the non-foamed layer is preferably 0.1 atomic percent or more, more preferably 0.2 atomic percent or more, and even more preferably 0.5 atomic percent or more. There is no particular upper limit to the amount of inorganic elements in the non-foamed layer, but from the viewpoint of surface smoothness, the amount of inorganic elements is preferably 20 atomic percent or less. The amounts of inorganic elements listed above represent the total amounts of inorganic elements confirmed by SEM-EDX measurements.

[0016] The types of inorganic elements present in the non-foamed layer are 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 inorganic elements in the non-foamed layer further improves the vacuum formability of the composite. This is thought to be because the interaction of Si and Al with the resin enhances the stress distribution effect. From the viewpoint of improving the vacuum formability of the composite, it is preferable that the amount of at least one of Si and Al atoms in the non-foamed layer, as measured by SEM-EDX of the cross-section of the composite, be 0.01 atomic percent or more, and more preferably 0.1 atomic percent or more.

[0017] The amount of inorganic elements in the non-foamed 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 a device that allows elemental analysis to be performed on the field of view while observing the morphology with the SEM. It identifies the type and amount of elements from the X-rays generated by irradiating the sample with an electron beam. The amount of inorganic elements in the non-foamed layer is determined by measuring the average thickness from the interface between the resin foam and the non-foamed layer to the outermost surface of the non-foamed layer using SEM-EDX measurement, and then measuring the amount of inorganic elements in the layer with that average thickness. The average thickness is best determined by measuring the thickness at 10 equally spaced points and averaging them. Note that the area from the interface between the resin foam and the non-foamed layer to the outermost surface of the non-foamed layer is, for example, region a in Figure 1 if the non-foamed layer is a single layer, and region a' in Figure 3 if the non-foamed layer is multilayered.

[0018] (Composition of the non-foamed layer) The non-foamed layer contains resin and inorganic particles. As described above, the non-foamed layer may be a single layer or a multi-layer, but it includes at least an inorganic particle-containing layer containing resin and inorganic particles. In other words, the non-foamed layer may consist only of an inorganic particle-containing layer containing resin and inorganic particles, or it may comprise the inorganic particle-containing layer and a resin layer that does not contain inorganic particles. Furthermore, whether or not inorganic particles are present can be determined by morphological observation using the SEM-EDX method 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 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 resins such as polypropylene resins (PP), polyethylene resins (PE), and poly(1-)butene resins; 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 resins and olefin thermoplastic elastomers (TPO), with polyolefin resins being more preferred, and polyethylene resins being even more preferred. Using these resins makes it easier to improve the vacuum formability of the composite. Furthermore, when the resin foam layer described later is a polyolefin resin foam, the resin in the inorganic particle-containing layer is preferably a polyethylene resin. This improves the adhesion between the resin foam layer and the non-foamed layer, and also improves the vacuum formability.

[0021] As for olefin-based thermoplastic elastomers (TPO), blended, dynamically crosslinked, and polymerized types can all be used. 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 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 (TPOs) include blends of polyethylene and EPR, partially crosslinked polyethylene and EPR blends using organic peroxides, graft-modified polyethylene and EPR blends with unsaturated hydroxy monomers, derivatives of unsaturated carboxylic acids, etc., and butyl-grafted polyethylene.

[0022] The polyethylene resin is not particularly limited, but examples include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ethylene-α-olefin copolymers mainly composed of ethylene. These may be used individually or in combination of two or more. Among the polyethylene resins mentioned above, linear low-density polyethylene is preferred.

[0023] (Inorganic particles) The inorganic particle-containing layer contains inorganic particles. While not particularly limited, examples of inorganic particles include fumed silica, mesoporous silica, silica gel, talc, layered double hydroxides, synthetic zeolites, naturally occurring zeolites, 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 may be used individually, mixed in combination of two or more, or as particles formed by stacking the above-mentioned compounds, or as core-shell particles, hollow particles, aggregated particles, or alloy-like fused bodies synthesized using the above-mentioned substances as templates. The inorganic particles exemplified above may be porous or non-porous, but porous particles are preferred.

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

[0025] The inorganic material is preferably in particulate form, and its average particle size 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 material refers to the cumulative median diameter measured using a particle size distribution analyzer or SEM measurement.

[0026] The inorganic content 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 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 coated film, and more specifically, it is preferably a coated film formed by an inorganic particle-containing aqueous emulsion as described later. When the inorganic particle-containing layer is a coated film, the generation of odor can be reduced.

[0029] As described above, the non-foamed layer may include a resin layer (second non-foamed layer) that does not contain inorganic particles. By including a resin layer that does not contain inorganic particles in the composite, the surface smoothness can be easily improved. The above-mentioned resin layer is composed of a resin alone or a resin and other additives such as antioxidants. The resin included in the above-mentioned resin layer can be any of the resins described in the inorganic particle-containing layer above without any particular limitations, and among them, polyethylene-based resins or olefin-based thermoplastic elastomers (TPO) are preferred, and olefin-based thermoplastic elastomers (TPO) are more preferred.

[0030] The thickness of the resin layer (second non-foamed 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-foamed layer (the total thickness of the non-foamed layer) is not particularly limited, but from the viewpoint of improving the vacuum formability of the composite, it is, for example, 1 to 1000 μm, and preferably 5 to 600 μm. The thickness of the non-foamed layer is the thickness of the inorganic particle-containing layer if the non-foamed layer consists only of a resin and an inorganic particle-containing layer containing inorganic particles, and the total thickness of the inorganic particle-containing layer and the resin layer if the non-foamed layer comprises both an inorganic particle-containing layer and a resin layer that does not contain inorganic particles.

[0032] [Resin foam layer] The composite of the present invention comprises a resin foam layer. By including a resin foam layer, flexibility, lightness, and other properties can be imparted to the composite. The resin foam layer is not particularly limited and includes polyolefin resin foam, polystyrene foam, polyurethane foam, phenol 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, silicone resin foam, and the like. The resin foam layer can be made from 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. Furthermore, if the resin foam layer is a crosslinked polyolefin resin foam, it is formed by crosslinking and foaming a foamable resin composition containing a polyolefin resin.

[0034] (Polyolefin resin) Examples of polyolefin resins contained in the foamed resin composition include polyethylene resins, polypropylene resins, and ethylene vinyl acetate resins. From the viewpoint of improving the heat resistance and moldability of the resulting crosslinked polyolefin resin foam, it is preferable to include a polypropylene resin, and it is even more preferable to include both a polypropylene resin and a polyethylene resin.

[0035] Examples of polypropylene resins include homopolypropylene, ethylene-propylene random copolymers mainly composed of propylene, and ethylene-propylene block copolymers mainly composed of propylene. These may be used individually or in combination of two or more types. Among these, it is preferable to use ethylene-propylene random copolymers mainly composed of propylene. It should be noted that "mainly composed of propylene" means that in the polypropylene resin, the content of propylene-derived structural units is 75% by mass or more of the total monomer-derived structural units, and preferably 90% by mass or more. The same applies hereafter. The melt flow rate (hereinafter referred to as "MFR") of the above polypropylene 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 of the above polypropylene resin was measured in accordance with JIS K 7210 under conditions of a temperature of 230°C and a load of 21.2N.

[0036] The polyethylene resin is not particularly limited, but examples include low-density polyethylene, medium-density polyethylene, high-density polyethylene, linear low-density polyethylene, and ethylene-α-olefin copolymers mainly composed of ethylene. These may be used individually or in combination of two or more. Among the polyethylene resins mentioned above, linear low-density polyethylene is preferred. The density of linear low-density polyethylene is 0.900 to 0.925 g / cm³. 3 Preferably, it is 0.902~0.922 g / cm³. 3 It is preferable that it be so. The MFR of the above 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 above polyethylene resin was measured in accordance with JIS K 7210 under conditions of a temperature of 190°C and a load of 21.2N.

[0037] When the polyolefin resin contains a polypropylene resin, the foamed resin composition may further contain resins other than the polypropylene resin, specifically, polyolefin resins other than polypropylene resins such as polyethylene resins, and olefin elastomers. The total content of polyolefin resins other than polypropylene resins and olefin elastomers relative to the total amount of resin contained in the foamed 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 also 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 olefin-based thermoplastic elastomers are as described in the non-foamed layer section above. Furthermore, the foamed resin composition may also contain resins other than polyolefin resins and olefin-based elastomers.

[0038] <Antioxidant> The foamed resin composition preferably contains an antioxidant. The inclusion of an antioxidant can suppress oxidative degradation of the polyolefin resin and reduce the odor generation of the cross-linked polyolefin resin foam. The foamed resin composition preferably contains 0.1 to 5.0 parts by mass of antioxidant per 100 parts by mass of resin, and more preferably 1.0 to 4.0 parts by mass. By adding 0.5 parts by mass or more of antioxidant per 100 parts by mass of resin, oxidative degradation of the polyolefin resin is further suppressed, and the generation of odor in the cross-linked polyolefin resin foam can be reduced. Furthermore, by adding 5.0 parts by mass or less of antioxidant per 100 parts by mass of resin, it is possible to suppress the conversion of excess antioxidant into odor-causing substances.

[0039] The type of antioxidant is not particularly limited, but examples include phenolic antioxidants, sulfuric 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 the generation of odor in cross-linked 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. Antioxidants may be used individually or in combination of two or more types.

[0040] <Crosslinking agent> The foamed resin composition preferably contains a crosslinking aid. The amount of crosslinking aid in the foamed resin composition is preferably 2.0 to 5.0 parts by mass, and more preferably 2.5 to 4.7 parts by mass, per 100 parts by mass of resin contained in the foamed resin composition. By using a crosslinking aid of 2.0 parts by mass or more per 100 parts by mass of resin, heat resistance is improved and the generation of odor in 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 a crosslinking aid of 5.0 parts by mass or less per 100 parts by mass of resin, vacuum formability is improved and foaming defects are more easily prevented.

[0041] Examples of crosslinking aids include polyfunctional (meth)acrylate compounds such as trifunctional (meth)acrylate compounds and difunctional (meth)acrylate compounds, as well as compounds having three functional groups in one molecule. Other crosslinking aids include compounds having two functional groups in one molecule, such as divinylbenzene, diallyl phthalate, diallyl terephthalate, diallyl isophthalate, ethyl vinylbenzene, lauryl methacrylate, and stearyl methacrylate. Examples of trifunctional (meth)acrylate compounds include trimethylolpropane trimethacrylate and trimethylolpropane triacrylate. Examples of difunctional (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 trialyl ester, 1,2,4-benzenetricarboxylic acid trialyl ester, and trialyl isocyanurate. Crosslinking agents can be used alone or in combination of two or more types. 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> There are two methods for foaming a foamable resin composition: chemical foaming and physical foaming. Chemical foaming is a method in which bubbles are formed by gas produced by the thermal decomposition of compounds added to the foamable resin composition, while physical foaming is a method in which cells are formed by impregnating the foamable resin composition with a low-boiling point liquid (foaming agent) and then volatilizing the foaming agent. The foaming method is not particularly limited, but chemical foaming is preferred. As a blowing agent, a thermal decomposition type blowing agent is preferably used. For example, an organic or inorganic chemical blowing 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 bicarbonate, azodicarbonamide, ammonium nitrite, and azobisisobutyronitrile; nitroso compounds such as N,N'-dinitrosopentamethylenetetramine; hydrazine derivatives such as hydrazodicarbonamide, 4,4'-oxybis(benzenesulfonyl hydrazide), and toluenesulfonyl hydrazide; guanidine salts such as guanidine phosphate, guanidine bicarbonate, guanidine hydrochloride, and guanidine sulfate; and semicarbazide compounds such as toluenesulfonyl semicarbazide.

[0043] Examples of inorganic blowing agents include azodicarboxylate metal salts (such as barium azodicarboxylate), sodium carbonate, sodium bicarbonate, sodium borohydride, and anhydrous monosodium citrate. Among these, azo compounds and nitroso compounds are preferred from the viewpoint of obtaining fine bubbles, as well as from the viewpoints of economy and safety, azodicarbonamide, azobisisobutyronitrile, and N,N'-dinitrosopentamethylenetetramine are more preferred, and azodicarbonamide is particularly preferred. The foaming agent can be used alone or in combination of two or more types. From the viewpoint of easily setting the foaming ratio of the foam to the foamable resin composition, the amount of foaming agent added 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 polyolefin resin.

[0044] <Other additives> The foamed resin composition may contain, as needed, additives commonly used in foams, such as heat stabilizers, colorants, flame retardants, antistatic agents, fillers, rust inhibitors, and decomposition temperature regulators.

[0045] <Foaming ratio> The foaming 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. A foaming ratio above a certain level makes it easier to ensure the flexibility of the foam. Conversely, a foaming ratio below a certain level can improve the mechanical strength of the foam. The foaming ratio is calculated by comparing the specific volume of the foamed resin composition before foaming with the specific volume of the foamed resin layer after foaming (unit: cm³). 3 The specific volume (per g) was measured and calculated by (specific volume of the foamed resin layer) / (specific volume of the foamed resin composition before foaming).

[0046] <Crosslinking degree> The degree of crosslinking of the resin foam layer of the present invention is preferably 30 to 60% by mass. When the degree of crosslinking is 30 to 60% by mass, the mechanical strength, flexibility, and vacuum formability of the foam can be improved in a balanced manner. From the viewpoint of improving the mechanical strength, flexibility, and vacuum formability of the foam in a balanced manner, 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. Approximately 100 mg of a test specimen is taken from the resin foam layer, and its mass A (mg) is accurately weighed. Next, this test specimen is heated in xylene 30 cm³ at 120°C. 3 After immersion for 24 hours, the material is filtered through a 200-mesh wire mesh, and the insoluble material on the mesh is collected. This material is then vacuum-dried, and the mass B (mg) of the insoluble material is accurately weighed. From the obtained value, the degree of crosslinking (mass %) is calculated using the following formula. Crosslinking degree (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] [complex] The composite of the present invention comprises the resin foam layer and the non-foam layer described above. The composite will be described below.

[0049] <Ratio of thickness> 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. The ratio of the thickness of the resin foam layer to the thickness of the inorganic particle-containing layer in the non-foamed 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 keeping the thickness ratio within the above range, it becomes easier to improve the vacuum formability of the composite.

[0050] <Tensile elongation> The composite of the present invention has a tensile elongation of 80% or more at least one of its MD tensile elongation and TD tensile elongation at 160°C. This improves vacuum formability at high temperatures. The MD tensile elongation and TD tensile elongation of the composite at 160°C are preferably 90% or more for at least one of them, more preferably 100% or more, and even more preferably 140% or more. Furthermore, 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. There is no particular upper limit to the tensile elongation, but it is, for example, 500%. "MD" stands for Machine Direction, meaning the direction that coincides with the extrusion direction of the resin foam layer. "TD" stands for Transverse Direction, meaning the direction that is perpendicular to MD and parallel to the resin foam layer. The tensile elongation can be adjusted to a desired value by adjusting the composition and thickness of the resin foam layer and the non-foamed layer. Tensile elongation can be measured in accordance with JIS K6767.

[0051] <Inorganic residue amount> The amount of inorganic residue when the composite is burned at 500 °C is preferably 0.05 g / m 2 or more. When the amount of inorganic residue is 0.05 g / m 2 or more, it becomes easier to adjust the tensile elongation within the above range, and the vacuum formability at high temperatures is improved. The amount of inorganic residue is preferably 0.1 g / m 2 or more, and more preferably 0.5 g / m 2 or more. The upper limit value of the amount of inorganic residue is not particularly limited, but from the viewpoint of the surface smoothness of the composite, etc., the amount of inorganic residue is preferably 5 g / m 2 or less. Note that the above amount of inorganic residue is the amount of inorganic residue per unit area (m 2 ) of the composite, and is calculated from the amount of residue when the composite is burned at 500 °C for 240 minutes under air.

[0052] [Method for producing composite] The method for producing the composite of the present invention is not particularly limited, but examples include a method comprising a step (A) of producing a resin foam layer and a step (B) of forming a non-foam layer on at least one surface of the resin foam layer produced in 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 shape to produce a foamable sheet (Step 2) A step of irradiating the foamable sheet with ionizing radiation to produce a crosslinked foamable sheet (Step 3) A step of foaming the crosslinked foamable sheet to produce a resin foam layer

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

[0055] (Process 2) Step 2 is a process of manufacturing a cross-linked foamed sheet by irradiating a foamed sheet with ionizing radiation. When irradiating with ionizing radiation, the irradiation dose is preferably 1 to 10 Mrad, and more preferably 1.5 to 5 Mrad, if the resin foam layer is a cross-linked polyolefin resin foam. Ionizing radiation may be applied to one side of the foamed sheet or to both sides. Examples of ionizing radiation include electron beams, alpha rays, beta rays, gamma rays, and X-rays. Among these, electron beams are preferred from the viewpoint of productivity and uniform irradiation.

[0056] (Step 3) Step 3 is a process of foaming a cross-linked foam sheet to produce a sheet-like resin foam layer. Methods for foaming the cross-linked foam sheet include a batch method such as an oven, and a continuous foaming method in which the cross-linked foam sheet is continuously passed through a heating furnace. The temperature at which the cross-linked foamed sheet is foamed is approximately 150 to 320°C when the foamed resin layer is a cross-linked polyolefin resin foam. There are no particular limitations on the method for adjusting the temperature to the above temperature, but hot air may be used, or infrared rays in the near-infrared wavelength region, the far-infrared wavelength region, or both wavelength regions may be used. Furthermore, after foaming, or while foaming, the crosslinked foamable sheet may be stretched in either the MD direction or the TD direction, or both.

[0057] <Process (B)> Step (B) is a step of forming a non-foamed layer on at least one side of the resin foam layer manufactured in step (A). One method for forming a non-foamed layer on at least one side of a foamed resin layer is to use an aqueous emulsion to form an inorganic particle-containing layer in the non-foamed layer. For example, a non-foamed layer can be formed on at least one surface of the foamed resin layer by following steps 4 to 6. (Step 4) Step to prepare an aqueous emulsion. (Step 5) A step to prepare an aqueous emulsion containing inorganic particles by dispersing inorganic particles in an aqueous emulsion. (Step 6) A step of applying an 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 the 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 that is formed. That is, if the resin contained in the inorganic particle-containing layer is a polyethylene resin, then the resin particles contained in the aqueous emulsion are polyethylene resin particles.

[0059] Aqueous emulsions are preferably obtained by emulsion polymerization of monomers for producing resin particles. Monomers for producing resin particles include, for example, ethylene monomers when the resin particles are polyethylene-based resins, and α-olefin monomers with about 3 to 10 carbon atoms, which are used as needed. Specifically, aqueous emulsions can be produced by adding a surfactant as an emulsifier and monomers to a dispersion medium mainly composed of water (for example, a dispersion medium containing 90% by mass or more of water, preferably a dispersion medium consisting of water), and emulsion polymerization of the monomers while stirring. In emulsion polymerization, additives such as polymerization initiators, chain transfer agents, and stabilizers may be added as needed.

[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 formed inorganic particle-containing layer. The amount of inorganic particles in the inorganic particle-containing aqueous emulsion relative to 100 parts by mass of resin particles is the same as the amount of inorganic particles relative to 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. There are no particular limitations on the method of applying the inorganic particle-containing aqueous emulsion; various coaters can be used. For example, it can be applied using a bar coater, comma coater, dip coater, roll coater, spin coater, flow coater, knife coater, spray coater, etc. The drying temperature is, for example, 40 to 160°C, preferably 60 to 130°C.

[0062] By performing steps 4 to 6 described above, a composite is obtained consisting of a resin foam layer and a non-foam layer laminated on at least one side of the resin foam layer. In this case, the non-foam layer is composed of a single layer of inorganic particle-containing material and is a coated film of an inorganic particle-containing aqueous emulsion. The above method involves forming a composite using an aqueous emulsion, but the method for forming a non-foaming layer is not limited to using an aqueous emulsion. For example, an inorganic particle-containing layer constituting the non-foamed layer may be separately manufactured by extrusion molding or the like, and the inorganic particle-containing layer may be laminated to at least one surface of the resin foam layer to form a composite. Among the methods described above, the method using an aqueous emulsion is preferred because it reduces the odor of the resulting complex.

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

[0064] When the non-foamed layer is made into a multilayer structure, for example, a resin layer (such as a resin film) that does not contain inorganic particles can be laminated onto the surface of an 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 include methods of heat bonding by heating and pressurizing with a press, radiant heater, near-infrared or far-infrared rays, etc., or methods using adhesives or sealants.

[0066] <Application> The composite material of the present invention can be formed by various molding methods such as vacuum forming and used as a heat insulating material, cushioning material, etc. The composite material of the present invention is particularly suitable for use in the automotive field as an interior material for automobiles, such as ceiling materials, doors, and instrument panels. [Examples]

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

[0068] [Measurement method] The measurement and evaluation methods for each physical property are as follows:

[0069] <Amount of inorganic elements (atomic %) in the non-foamed layer> The cross-section of the composite was measured using a SEM-EDX instrument (JEOL Ltd. "JSM-IT100") to determine the amount (atomic %) of inorganic elements in the non-foamed layer. The measurement conditions for SEM-EDX were as follows: Field of view magnification: 2000x Observation field of view: 125.0 × 95.0 μm Pressurized voltage: 10kV WD: 10mm That's what I decided. Furthermore, we confirmed whether or not Si atoms or Al atoms were present in the non-foamed layer and measured the amount (atomic %) of these atoms in the non-foamed layer.

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

[0071] <Amount of inorganic residue after combustion at 500°C> The amount of inorganic residue was measured when the composite was burned in air at 500°C for 240 minutes. The amount of inorganic residue was measured per unit area (m²) of the composite. 2 This refers to the amount of inorganic residue per unit area.

[0072] <Foaming ratio and degree of crosslinking of the resin foam layer> The foaming ratio and degree of crosslinking of the resin foam layer were measured by the method described in the specification.

[0073] <Evaluation of high-temperature vacuum formability> For the composites prepared in each example and comparative example, the vacuum formability was evaluated by the cup molding reduction ratio (cup height / cup diameter = 0.68–0.98) under conditions where the mold temperature was set to 300–400°C and the test specimen temperature was 160°C. Vacuum formability was evaluated according to the following criteria. In the experiment, the reduction ratio (cup height / cup diameter) was gradually increased, and vacuum forming was performed for each case. The formability was evaluated by the reduction ratio (cup height / cup diameter) at which tearing occurred in the composite or when a thin, transparent area appeared in part of the composite. (Evaluation Criteria) A 0.92 or higher B 0.86-0.90 C 0.80-0.84 D 0.78 or less

[0074] [Ingredients used] The components used in each example and comparative example are as follows: (Raw materials for the resin foam layer) • Polypropylene resin (1): Homo PP, manufactured by Prime Polymer, product name "J106G", MFR 15g / 10 min • Polypropylene resin (2): Random PP, manufactured by Sumitomo Chemical Co., Ltd., product name "AD571", density 0.90 g / cm³ 3 MFR 0.5g / 10 minutes (230℃) • LLDPE: Linear low-density polyethylene, manufactured by Prime Polymer, product name "Ultrasex 1020L", density 0.91 g / cm³ 3 MFR 2.0g / 10 minutes (190℃) • TPO: Olefin-based thermoplastic elastomer, manufactured by Basell, product name "Softell CA 02 A", MFR 0.6g / 10min (230℃) • EPDM: Olefin-based elastomer, manufactured by Mitsui Chemicals, Inc., product name "3045" • Foaming agent: Azodicarbonamide, manufactured by Otsuka Chemical Co., Ltd., product name "SO-L", decomposition temperature: 197℃, average particle size: 3.2μm • Phenolic antioxidant: Manufactured by BASF Japan, product name "Irganox 1010" • Crosslinking agent: 1,9-nonanediol dimethacrylate, manufactured by Kyoeisha Chemical Co., Ltd., product name "Light Ester 1.9ND", viscosity 8 mPa·s / 25℃

[0075] (Raw materials for the non-foamed layer) • Inorganic particle-containing aqueous emulsion (1): An inorganic particle-containing aqueous emulsion (1) was prepared by dispersing silica gel (SiO2) in an aqueous emulsion containing dispersed polyethylene resin particles. The amount of silica gel (SiO2) in the inorganic particle-containing aqueous emulsion (1) was 95 parts by mass per 100 parts by mass of polyethylene resin particles. The average particle size of the silica gel (SiO2) used was 1 μm.

[0076] • Inorganic particle-containing aqueous emulsion (2): An inorganic particle-containing aqueous emulsion (2) was prepared by dispersing magnesium oxide (MgO) in an aqueous emulsion containing dispersed polyethylene resin particles. The amount of magnesium oxide (MgO) in the inorganic particle-containing aqueous emulsion (2) was 10 parts by mass per 100 parts by mass of polyethylene resin particles. The average particle size of the magnesium oxide (MgO) used was 8 μm.

[0077] • Inorganic particle-containing aqueous emulsion (3): An inorganic particle-containing aqueous emulsion (3) was prepared by dispersing aluminum hydroxide (Al(OH)3) in an aqueous emulsion containing dispersed polyethylene resin particles. The amount of aluminum hydroxide (Al(OH)3) in the inorganic particle-containing aqueous emulsion (3) was 55 parts by mass per 100 parts by mass of polyethylene resin particles. The average particle size of the aluminum hydroxide (Al(OH)3) used was 5 μm.

[0078] • Inorganic particle-containing aqueous emulsion (4): An inorganic particle-containing aqueous emulsion (4) was prepared by dispersing aluminum oxide (Al2O3) in an aqueous emulsion in which polyethylene resin particles were dispersed. The amount of aluminum oxide (Al2O3) in the inorganic particle-containing aqueous emulsion (4) was 65 parts by mass per 100 parts by mass of polyethylene resin particles. The average particle size of the aluminum oxide (Al2O3) used was 3 μm.

[0079] • Inorganic particle-containing aqueous emulsion (5)... An inorganic particle-containing aqueous emulsion (5) was prepared by dispersing calcium carbonate (CaCO3) in an aqueous emulsion in which polyethylene resin particles were dispersed. The amount of calcium carbonate (CaCO3) in the inorganic particle-containing aqueous emulsion (5) was 15 parts by mass per 100 parts by mass of polyethylene resin particles. The average particle size of the calcium carbonate (CaCO3) used was 7 μm.

[0080] • Inorganic particle-containing aqueous emulsion (6)... An inorganic particle-containing aqueous emulsion (6) was prepared by dispersing zeolite in an aqueous emulsion in which polyethylene resin particles were dispersed. The amount of zeolite in the inorganic particle-containing aqueous emulsion (6) was 110 parts by mass per 100 parts by mass of polyethylene resin particles. 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, "Softell CA 02 A" manufactured by Basell, with an MFR of 0.6 g / 10 min (230°C).

[0082] [Example 1] (Manufacturing of resin foam layer) A foamed resin composition was obtained by mixing polypropylene resin (2), LLDPE, a phenolic antioxidant, a crosslinking aid, and a foaming agent in the proportions shown in Table 1. This composition was melt-kneaded at 180°C using a single-screw extruder to form a foamed sheet. Both sides of the foamed sheet were irradiated with ionizing radiation (electron beam) at an acceleration voltage of 1000 keV for 2.0 Mrad to obtain a crosslinked foamed sheet. Subsequently, the crosslinked foamed sheet was supplied to a vertical hot-air foaming furnace at a furnace temperature of 250°C, where it was heated and foamed while being stretched to obtain a crosslinked polyolefin resin foam with a thickness of 2.5 mm. (Manufacturing of the composite) As described above, an inorganic particle-containing aqueous emulsion (1) was applied to one side of the cross-linked polyolefin resin foam prepared using a roll coater, and then dried at a drying temperature of 100°C to form a non-foamed layer consisting of an inorganic particle-containing layer. In this way, a composite of cross-linked polyolefin resin foam and an inorganic particle-containing layer (non-foamed layer) was obtained.

[0083] [Examples 2-7, 9] A cross-linked polyolefin resin foam was obtained in the same manner as in Example 1, except that the composition of the foamed resin composition was changed as shown in Table 1. Then, a composite was obtained in the same manner as in Example 1, with the type of inorganic particle-containing aqueous emulsion as follows. In Example 2, an inorganic particle-containing aqueous emulsion (2) was used; in Example 3, an inorganic particle-containing aqueous emulsion (3); in Examples 4 and 9, an inorganic particle-containing aqueous emulsion (4); in Example 5, an inorganic particle-containing aqueous emulsion (5); and in Examples 6 and 7, an inorganic particle-containing aqueous emulsion (6) was used.

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

[0085] [Comparative Example 1] A cross-linked polyolefin resin foam was obtained in the same manner as in Example 1. Next, a 10 μm thick aluminum foil was attached to one side of the cross-linked polyolefin. The attachment was performed by heat lamination.

[0086] [Comparative Example 2] A cross-linked polyolefin resin foam was obtained in the same manner as in Example 1. Next, an aqueous emulsion (without inorganic particles) in which polyethylene resin particles were dispersed was applied to one side of the cross-linked 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 is a non-foamed layer that does not contain inorganic particles.

[0087] [Comparative Example 3] A cross-linked polyolefin resin foam was obtained in the same manner as in Example 1, except that the composition of the foaming resin composition was changed as shown in Table 1. Next, an aqueous emulsion (without inorganic particles) in which polyethylene resin particles were dispersed was coated onto one side of the cross-linked 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 resin film with a thickness of 500 μm formed of TPO was laminated onto the surface of the polyethylene resin layer by heat lamination. As described above, a composite was obtained in which a cross-linked polyolefin resin foam, a polyethylene resin layer, and a resin film (TPO) were laminated in this order. The polyethylene resin layer and the resin film are non-foamed layers (containing no inorganic particles).

[0088] [Table 1]

[0089] The composites of Examples 1 to 9 have a non-foamed layer on one side of the resin foam layer, and the non-foamed layer comprises an inorganic particle-containing layer containing resin and inorganic particles. When the cross-section of the composite is measured by SEM-EDX, the amount of inorganic elements in the non-foamed layer is 0.01 atomic percent 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 that satisfy the requirements of the present invention exhibited good 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-foamed layer, exhibited poor high-temperature vacuum formability. [Explanation of Symbols]

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

Claims

1. A composite of a resin foam layer and a non-foam layer laminated on at least one surface of the resin foam layer, The non-foamed layer comprises at least an inorganic particle-containing layer containing a resin and inorganic particles, When the cross-section of the composite was measured by SEM-EDX, the amount of inorganic elements in the non-foamed layer was 0.5 atomic percent or more. A composite in which at least one of the MD tensile elongation and 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-foamed layer, as measured by SEM-EDX of the cross-section of the composite, is 0.01 atomic percent or more.

3. The amount of inorganic residue when burned at 500°C is 0.05 g / m³. ２ The composite according to claim 1 or 2.

4. The composite according to claim 1 or 2, wherein the resin foam layer is a polyolefin resin foam.

5. The composite according to 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-foamed layer is a polyolefin resin.

Images