JP2017170753A - Laminated foam sheet and molded material using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a laminated foam sheet that can achieve flexibility, formability and appearance, and to provide a molded material using the same.SOLUTION: Provided are: [1] a laminated foam sheet including a crosslinked polyolefin-based resin foam sheet (A) and an unexpanded resin sheet (B), and in which, characterized, said laminated foam sheet satisfies the following condition 1; and [2] a molded material obtained by integrally laminating a skin material on one surface of the laminated foam sheet. Condition 1: density (g/cm) of the foam sheet (A)×thickness (μm) of the resin sheet (B)=3.0 to 25.SELECTED DRAWING: None

Description

  The present invention relates to a laminated foam sheet used for automobile interior materials and the like, and a molded body using the same.

Crosslinked polyolefin-based resin foams are generally excellent in flexibility, lightness, and heat insulation, and are widely used as laminates with skin materials, heat insulation materials, cushion materials, and the like. Particularly in the automobile field, it is used for automobile interior materials such as ceiling materials, doors, and instrument panels.
Automobile interior materials are usually laminated with a resin sheet made of polyvinyl chloride or thermoplastic elastomer on one side of a sheet-like cross-linked polyolefin resin foam, followed by vacuum molding or compression molding. Secondary processing is performed by a method or the like to obtain a predetermined shape, which has been commercialized.

On the other hand, in recent years, with the diversification and sophistication of preferences, automobile interior materials have been required to have complicated shapes, and in addition, productivity improvement has been demanded. Therefore, it has been attempted to manufacture automobile interior materials by a low pressure injection molding method.
In the low pressure injection molding method, a resin is injected from an injection molding machine through a runner and a gate into a cavity of a mold as a product at a low pressure. For example, a molten resin, which is a base material for automobile interior materials, is injection-molded on one side of a foam sheet, but the foam sheet surface melts at the gate portion where the molten resin is injected, and a dent called a gate mark occurs. Has a dent on the opposite surface of the foamed sheet, and even a dent mark is formed on the skin material coated on the surface of the foamed sheet, which deteriorates the appearance.
In order to suppress the generation of gate marks, know-how has been studied to adjust the shape of the gate, the temperature and speed of the injected resin, etc. However, as a more fundamental solution, improvement of the resin material is required. It has been.

For example, Patent Document 1 includes a polypropylene resin having an MI of 0.4 to 2.0 and at least one DSC endothermic peak of 160 ° C. or higher, and a polyethylene resin having an MI of 0.5 to 10. There is disclosed a crosslinked polyolefin resin foam which is a crosslinked resin foam and has a ratio of (gel fraction B / gel fraction A) in a specific range.
In Patent Document 2, 25 to 50 parts by weight of a thermoplastic elastomer is added to 100 parts by weight of a polyolefin resin composition composed of a polypropylene resin having at least one DSC endothermic peak of 160 ° C. or higher and a polyethylene resin. A cross-linked polyolefin resin foam containing, having an apparent density of 50 to 100 kg / m ³ and a gel fraction of 45% or more is disclosed.

JP-A-8-59872 JP 2008-266589 A

However, the crosslinked polyolefin resin foam of Patent Document 1 has been required to be further improved in terms of elongation and flexibility.
In addition, the cross-linked polyolefin resin foam of Patent Document 2 has insufficient moldability, and the problem of poor appearance has not been solved even after being bonded to the skin material.
This invention is made | formed in view of the above situation, and makes it a subject to provide the laminated foam sheet which can stand up a softness | flexibility, a moldability, and external appearance property, and a molded object using the same. .

  As a result of intensive studies, the inventor previously laminated an unfoamed resin sheet on a crosslinked polyolefin resin foam sheet, and at that time, the density of the foam sheet and the thickness of the unfoamed resin sheet satisfy a certain relationship. As a result, it was found that a laminated foam sheet capable of elevating flexibility, moldability and appearance, and a molded body using the same, and the present invention was completed.

That is, the present invention provides the following [1] to [6].
[1] A laminated foamed sheet comprising a crosslinked polyolefin resin foamed sheet (A) and an unfoamed resin sheet (B), which satisfies the following condition 1.
Condition 1: Density (g / cm ³ ) of the foamed sheet (A) × Thickness (μm) of the resin sheet (B) = 3.0 to 25
[2] The laminated foam sheet according to [1], wherein the density of the foam sheet (A) is 0.03 to 0.12 g / cm ³ , and the thickness of the resin sheet (B) is 20 to 300 μm. .
[3] The laminated foam sheet according to the above [1] or [2], wherein the resin sheet (B) has a tensile strength of 11 to 90N.
[4] The laminated foam sheet according to any one of [1] to [3], wherein the resin constituting the resin sheet (B) is a polyolefin resin.
[5] The laminated foam sheet according to any one of the above [1] to [4], wherein a base resin is further injected and laminated and integrated on the resin sheet (B) side.
[6] The laminated foam sheet according to [5], wherein the resin constituting the resin sheet (B) has a melting point higher than that of the base resin.
[7] A molded body obtained by laminating and integrating a skin material on one surface of the laminated foamed sheet according to any one of [1] to [6].
[8] The molded article according to the above [7], which is an automobile interior material.

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to provide the laminated foam sheet which can stand up a softness | flexibility, a moldability, and an external appearance property, and a molded object using the same.

The laminated foam sheet of the present invention comprises a crosslinked polyolefin resin foam sheet (A) (hereinafter also simply referred to as “foam sheet (A)”) and an unfoamed resin sheet (B) (hereinafter simply referred to as “resin sheet (B)”). The foam sheet is also characterized in that the following condition 1 is satisfied.
Condition 1: Density (g / cm ³ ) of the foamed sheet (A) × Thickness (μm) of the resin sheet (B) = 3.0 to 25
Hereinafter, each component used for the laminated foam sheet of this invention is demonstrated.

[Crosslinked polyolefin resin foam sheet (A)]
As the cross-linked polyolefin resin foam sheet (A), a polyolefin resin composition containing a polyolefin resin such as a polypropylene resin, a polyethylene resin, an olefin thermoplastic elastomer (hereinafter referred to as “resin composition (a)”). And a foamed sheet.

<Polypropylene resin>
The polypropylene resin is not particularly limited, and examples thereof include a propylene homopolymer (homopolypropylene) and a copolymer of propylene and another olefin. The copolymer of propylene and another olefin may be any of a block copolymer, a random copolymer, and a random block copolymer, but is preferably a random copolymer (random polypropylene).
Other olefins copolymerized with propylene include, for example, α such as ethylene, 1-butene, 1-pentene, 4-methyl-1-pentene, 1-hexene, 1-octene, 1-nonene and 1-decene. -Olefins, among which ethylene is preferred. That is, the polypropylene resin is preferably an ethylene-propylene random copolymer.
The copolymer of propylene and other olefins is usually 90 to 99.5% by weight of propylene and 0.5 to 10% by weight of α-olefin other than propylene, but 95 to 99% by weight of propylene. %, And α-olefin other than propylene is preferably 1 to 5% by mass.

The polypropylene resin preferably has a melt flow rate (hereinafter also referred to as “MFR”) of 0.4 to 4.0 g / 10 minutes, more preferably 0.5 to 2.5 g / 10 minutes. preferable. By using the polypropylene resin having the above MFR, it becomes easy to improve the moldability when the resin composition (a) is processed into a foam and the moldability when the foam is secondarily molded.
Said polypropylene resin can be used individually or in combination of 2 or more types.

<Polyethylene resin>
Examples of the polyethylene resin include a low density polyethylene resin, a medium density polyethylene resin, a high density polyethylene resin, and a linear low density polyethylene resin.
The polyethylene resin preferably has an MFR of 1.0 to 5.0 g / 10 min, and more preferably 1.5 to 4.0 g / 10 min. By using the polyethylene resin having the above MFR, it becomes easy to improve the moldability when the resin composition (a) is processed into a foam and the moldability when the foam is secondarily molded.

Of the polyethylene resins, linear low density polyethylene resins (LLDPE) are more preferable. LLDPE is polyethylene having a density of 0.910 g / cm ³ or more and less than 0.950 g / cm ³ , and preferably has a density of 0.910 to 0.930 g / cm ³ . When the resin composition (a) contains LLDPE having a low density, the processability when processing into a foamed sheet, the moldability when forming the foamed sheet into a molded body, and the like are likely to be good. In addition, the said density was measured based on JISK7112.
LLDPE is usually a copolymer of ethylene and a small amount of an α-olefin containing ethylene as a main component (50% by mass or more, preferably 70% by mass or more of all monomers). Here, examples of the α-olefin include those having 3 to 12 carbon atoms, preferably 4 to 10 carbon atoms, and specifically, 1-butene, 1-pentene, 1-hexene, 4-methyl-1 -Pentene, 1-heptene, 1-octene and the like. In the copolymer, these α-olefins can be used alone or in combination of two or more.
Moreover, a polyethylene-type resin can also be used individually or in combination of 2 or more types.

<Olefin-based thermoplastic elastomer>
As the olefin-based thermoplastic elastomer (TPO), any of a blend type, a dynamic crosslinking type, and a polymerization type can be used. More specifically, a copolymer having polypropylene as a hard segment and ethylene as a soft segment and a small amount of a diene component, such as ethylene-propylene rubber (EPR), ethylene-propylene-diene rubber (EPDM); polyethylene and Blend of EPM; Blend of polyethylene and EPM partially crosslinked with organic peroxide; Blend of polyethylene and EPM grafted with unsaturated hydroxy monomer, unsaturated carboxylic acid derivative, etc. Modified: butyl graft polyethylene and the like.
The MFR of the olefinic thermoplastic elastomer is preferably 0.8 to 5.0 g / 10 minutes, and more preferably 1.5 to 4.0 g / 10 minutes. By using the olefinic thermoplastic elastomer having the above MFR, it becomes easy to improve the moldability when the resin composition (a) is processed into a foam and the moldability when the foam is secondarily molded. .

The resin composition (a) may be composed of a polyolefin resin alone, but may contain a resin component other than the polyolefin resin as long as the object of the present invention is not impaired.
Examples of the resin component include an ethylene-vinyl acetate copolymer, an ethylene-acrylic acid copolymer, an ethylene- (meth) alkyl acrylate copolymer, or a modified copolymer obtained by copolymerizing maleic anhydride with these copolymers. Etc.
The polyolefin resin is usually contained in an amount of 70% by mass or more, preferably 80 to 100% by mass, more preferably 90 to 100% by mass, based on the total amount of the resin contained in the resin composition (a). .

The resin composition (a) preferably contains a polypropylene resin in an amount of 40% by mass or more, more preferably 45% by mass or more, based on the total amount of the resin contained in the resin composition (a). And it is preferable to contain 90 mass% or less.
As described above, the polypropylene resin is preferably random polypropylene, but may be a mixture of homopolypropylene and random polypropylene.
As described above, the foamed sheet (A) can have good mechanical strength, heat resistance, and the like of the foamed sheet (A) by using the polypropylene resin as a main component.

The resin composition (a) preferably contains a polyethylene resin in addition to the polypropylene resin as a polyolefin resin. In this case, the polyethylene resin is preferably contained in an amount of 1% by mass or more, more preferably 5% by mass or more, and more preferably 30% by mass with respect to the total amount of the resin contained in the resin composition (a). It is preferable to contain below, and it is more preferable to contain below 20 mass%.
Further, the resin composition (a) preferably contains an olefinic thermoplastic elastomer. In this case, the olefinic thermoplastic elastomer is preferably contained in an amount of 10% by mass or more, more preferably 20% by mass or more, and more preferably 30% by mass with respect to the total amount of the resin contained in the resin composition (a). It is more preferable to contain more than this, and it is preferable to contain less than 50 mass%, and it is more preferable to contain 45 mass% or less.
The resin composition (a) contains a polyethylene resin and an olefinic thermoplastic elastomer in addition to the polypropylene resin, so that it is easy to improve workability and moldability while improving mechanical strength, heat resistance and the like. .

<Additives>
The resin composition (a) used for this invention contains a foaming agent as an additive other than said resin component normally. Moreover, it is preferable to contain one or both of a crosslinking assistant and an antioxidant.

(Foaming agent)
As a method of foaming the resin composition (a), there are a chemical foaming method and a physical foaming method. The chemical foaming method is a method in which bubbles are formed by gas generated by thermal decomposition of the compound added to the resin composition (a), and the physical foaming method is a method in which a low boiling point liquid (foaming agent) is added to the resin composition ( After impregnating a), the foaming agent is volatilized to form cells. The foaming method is not particularly limited, but the chemical foaming method is preferable from the viewpoint of obtaining a uniform closed cell foam.
As the foaming agent, a thermal decomposition type foaming agent is used. For example, an organic or inorganic chemical foaming agent having a decomposition temperature of about 160 to 270 ° C. can be used.
Examples of organic foaming agents include azodicarbonamide, azodicarboxylic acid metal salts (such as barium azodicarboxylate), azo compounds such as azobisisobutyronitrile, nitroso compounds such as N, N′-dinitrosopentamethylenetetramine, Examples thereof include hydrazine derivatives such as hydrazodicarbonamide, 4,4′-oxybis (benzenesulfonylhydrazide) and toluenesulfonylhydrazide, and semicarbazide compounds such as toluenesulfonyl semicarbazide.

Examples of the inorganic foaming agent include ammonium acid, sodium carbonate, ammonium hydrogen carbonate, sodium hydrogen carbonate, ammonium nitrite, sodium borohydride, anhydrous monosodium citrate, and the like.
Among these, azo compounds and nitroso compounds are preferable from the viewpoint of obtaining fine bubbles, and from the viewpoints of economy and safety, and azodicarbonamide, azobisisobutyronitrile, N, N′-dinitrosopentamethylene. Tetramine is more preferred, and azodicarbonamide is particularly preferred.
A foaming agent can be used individually or in combination of 2 or more types.
The addition amount of the pyrolytic foaming agent is preferably 1 to 30 parts by mass, more preferably 2 to 15 parts by mass with respect to 100 parts by mass of the resin component, from the viewpoint of appropriately foaming the foam without bursting. .

(Crosslinking aid)
A polyfunctional monomer can be used as a crosslinking aid. For example, trifunctional (meth) acrylate compounds such as trimethylolpropane trimethacrylate, trimethylolpropane triacrylate; trimellitic acid triallyl ester, 1,2,4-benzenetricarboxylic acid triallyl ester, triallyl isocyanurate, etc. Compound having three functional groups in one molecule; bifunctional such as 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, neopentyl glycol dimethacrylate ( Compounds having two functional groups in one molecule such as (meth) acrylate compounds and divinylbenzene; diallyl phthalate, diallyl terephthalate, diallyl isophthalate, ethyl vinyl benzene, lauryl methacrylate, stearyl methacrylate Over doors and the like. In these, a trifunctional (meth) acrylate type compound is more preferable.
The crosslinking aids can be used alone or in combination of two or more.
By adding a crosslinking aid to the resin composition (a), the resin composition (a) can be crosslinked with a small ionizing radiation dose. Therefore, cutting and deterioration of each resin molecule accompanying irradiation with ionizing radiation can be prevented.
The content of the crosslinking aid is 0.2 to 20 with respect to 100 parts by mass of the resin composition (a) from the viewpoint of adjusting the degree of crosslinking and ease of control when foaming the resin composition (a). A mass part is preferable and 0.5-15 mass parts is more preferable.

(Antioxidant)
Examples of the antioxidant include phenol-based antioxidants, sulfur-based antioxidants, phosphorus-based antioxidants, and amine-based antioxidants. In these, a phenolic antioxidant and a sulfur type antioxidant are preferable, and it is more preferable to use a phenolic antioxidant and a sulfur type antioxidant together.
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, tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate ] Methane etc. are mentioned.
Examples of the sulfur-based antioxidant include dilauryl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate, pentaerythrityl tetrakis (3-lauryl thiopropionate), and the like.
These antioxidants can be used alone or in combination of two or more.
0.1-10 mass parts is preferable with respect to 100 mass parts of resin compositions (a), and, as for content of antioxidant, 0.2-5 mass parts is more preferable.
In addition, the resin composition (a) may be prepared by using a decomposition temperature adjusting agent such as zinc oxide, zinc stearate, or urea, a flame retardant, a metal harm preventing agent, an antistatic agent, a stabilizer, a filler, a pigment, and the like as necessary. Additives other than those described above may be included.

[Foamed sheet (A)]
The foam sheet (A) used in the present invention is obtained by crosslinking and foaming the above resin composition (a).
(density)
The density (apparent density) of the foam sheet (A) is preferably 0.03 g / cm ³ or more, more preferably 0.032 g / cm ³ or more, and still more preferably, from the viewpoint of improving the flexibility and mechanical strength in a balanced manner. Is 0.035 g / cm ³ or more, and preferably 0.12 g / cm ³ or less, more preferably 0.11 g / cm ³ or less, and even more preferably 0.10 g / cm ³ or less.
(Foaming ratio)
The expansion ratio of the foamed sheet (A) is calculated as the reciprocal of the density, and is preferably 8 cm ³ / g or more, more preferably 9 cm ³ / g or more, from the viewpoint of improving the flexibility and mechanical strength in a good balance. It is preferably 10 cm ³ / g or more, and preferably 33 cm ³ / g or less, more preferably 31 cm ³ / g or less, still more preferably 29 cm ³ / g or less.

(Crosslinking degree)
The degree of crosslinking (% by mass) of the entire foamed sheet (A) is preferably 25% or more, more preferably 30% or more, and still more preferably 35% from the viewpoint of improving the flexibility, mechanical strength, and moldability in a balanced manner. And preferably 65% or less, more preferably 60% or less, and still more preferably 55% or less.
In addition, the measuring method of a crosslinking degree can be measured by the method as described in the Example mentioned later.

(Thickness)
The thickness of the foam sheet (A) is preferably 0.5 mm or more, more preferably about 0.8 mm or more, still more preferably 1.2 mm or more, and preferably 8 mm or less, more preferably 6 mm or less, still more preferably. Is 5 mm or less. When the thickness of the foam is within these ranges, it is easy to improve both flexibility and moldability, and it becomes easy to mold the automobile interior material.

(25% compression hardness)
The 25% compression hardness of the foamed sheet (A) is preferably 30 kPa or more, more preferably 35 kPa or more, still more preferably 40 kPa or more, from the viewpoint of ensuring mechanical strength and the like, and from the viewpoint of enhancing flexibility. , Preferably 90 kPa or less, more preferably 85 kPa or less, still more preferably 80 kPa or less, still more preferably 70 kPa or less.

<Method for producing foam sheet (A)>
The foam sheet (A) is obtained by, for example, melting and kneading the resin composition (a) to form a desired shape, then irradiating ionizing radiation to crosslink the resin composition (a), and further heating and foaming. Can be manufactured.
Specifically, a production method having the following steps 1 to 3 is more preferable.
Step 1: Step of obtaining a resin composition (a) having a predetermined shape such as a sheet after melt-kneading each component constituting the resin composition (a) Step 2: Resin composition (a Step of irradiating ionizing radiation to) and crosslinking step 3: Step of heating the resin composition (a) crosslinked in step 2 to a temperature higher than the decomposition temperature of the pyrolytic foaming agent to obtain a foamed sheet

In step 1, first, each component constituting the resin composition (a) is supplied to a kneading apparatus, melted and kneaded at a temperature lower than the decomposition temperature of the thermally decomposable foaming agent, and then melt-kneaded resin composition. (A) is preferably formed into a desired shape such as a sheet with a kneading apparatus used in melt kneading.
Examples of the kneading apparatus used here include general-purpose kneading apparatuses such as injection molding machines, extruders (single screw extruders, twin screw extruders, etc.), Banbury mixers, rolls, and the like. An extruder is preferred, and if an injection molding machine is used, it can be manufactured with high productivity.
The resin temperature inside the injection molding machine or the extruder is preferably 120 to 220 ° C, more preferably 140 to 200 ° C, still more preferably 150 to 195 ° C.

In step 2, the resin composition (a) molded into a desired shape is irradiated with ionizing radiation.
Examples of ionizing radiation include electron beams, α rays, β rays, γ rays, X rays, and the like. In these, an electron beam is preferable from a viewpoint of performing productivity and irradiation uniformly.
For example, when the resin composition (a) is formed into a sheet shape, the ionizing radiation may be irradiated on only one surface of the sheet or both surfaces, but both surfaces may be irradiated. preferable.
The irradiation amount of ionizing radiation may be an amount capable of obtaining a desired degree of crosslinking in consideration of the thickness of the foamable resin composition to be irradiated, etc., but is usually 0.1 to 10 Mrad, preferably 0. .2 to 5 Mrad is more preferable.

In Step 3, after the resin composition (a) is crosslinked by irradiation with ionizing radiation as described above, the resin composition (a) is heated to a temperature equal to or higher than the decomposition temperature of the foaming agent, and foamed and molded. It is performed simultaneously and a foam sheet (A) can be obtained.
Here, the temperature at which the resin composition (a) is heated and foamed depends on the decomposition temperature of the thermally decomposable foaming agent used as the foaming agent, but is usually 140 to 300 ° C, preferably 150 to 280 ° C, more preferably 160. ~ 260 ° C. In addition, the foamed sheet may be stretched in the MD direction or the CD direction or both after foaming or while foaming.
The foamed sheet (A) of the present invention preferably has a closed cell structure, but may have a closed cell structure containing open cells.

[Unfoamed resin sheet (B)]
The unfoamed resin sheet (B) is bonded and laminated to the foamed sheet (A).
The unfoamed resin sheet (B) is laminated on the foamed sheet (A) in advance, and at that time, by satisfying the condition 1, the generation of gate marks due to the base resin injected and laminated at the time of molding production Can be suppressed, and appearance defects can be prevented.
Examples of the resin sheet (B) include a thermoplastic resin sheet, a thermoplastic elastomer sheet, and a non-woven fabric, but a thermoplastic resin sheet is preferable.
Examples of the material of the thermoplastic resin sheet include polyolefin resins such as polypropylene and polyethylene, polyester resins such as polyethylene terephthalate, and polyamide resins.
Among these, from the viewpoints of adhesion to the foamed sheet (A) and versatility, polyolefin resins are preferable, and polypropylene resins are more preferable. The polypropylene resin is the same as the preferred example of the polypropylene resin described in the above-mentioned column of the crosslinked polyolefin resin except that it is not crosslinked or foamed.
The form of the unfoamed resin sheet (B) may be either a single layer or a multilayer.

(Thickness)
From the viewpoint of improving the mechanical strength of the laminated foam sheet of the present invention, the thickness of the resin sheet (B) is preferably 20 μm or more, more preferably 40 μm or more, still more preferably 60 μm or more, and even more preferably 80 μm or more. From the viewpoint of improving the flexibility of the laminated foam sheet, it is preferably 300 μm or less, more preferably 280 μm or less, still more preferably 250 μm or less, and still more preferably 230 μm or less.
The melting point of the resin constituting the resin sheet (B) is higher than the melting point of the base resin bonded to the laminated foam sheet from the viewpoint of suppressing the occurrence of gate marks in the laminated foam sheet and improving the appearance. Preferably, it is more preferably 5 ° C or higher than the melting point of the base resin, and more preferably 10 ° C or higher. The melting point is preferably 150 ° C. or higher, more preferably 155 ° C. or higher, and still more preferably 160 ° C. or higher.
In addition, when using 2 or more types of resin, melting | fusing point uses the weighted average value.

(tensile strength)
From the viewpoint of improving the shear strength of the laminated foam sheet of the present invention, the tensile strength of the resin sheet (B) is preferably 11 N or more, more preferably 15 N or more, still more preferably 20 N or more, and still more preferably 25 N or more. From the viewpoint of improving the workability of the laminated foam sheet, it is preferably 90 N or less, more preferably 85 N or less, still more preferably 80 N or less, and even more preferably 75 N or less.
In addition, when there exists a difference in tensile strength by MD direction and TD direction of a resin sheet (B), the value of MD direction or TD direction with a large tensile strength is employ | adopted.
Moreover, the said tensile strength is a value in normal temperature (23 degreeC), and can be measured by the method as described in the Example mentioned later.

[Laminated foam sheet]
The laminated foam sheet of the present invention is formed by adhering a foam sheet (A) and a resin sheet (B) and satisfying the following condition 1.
Condition 1: Density (g / cm ³ ) of the foamed sheet (A) × Thickness (μm) of the resin sheet (B) = 3.0 to 25
Condition 1 is preferably 3.2 or more, more preferably 3.5 or more, still more preferably 3.7 or more, and preferably from the viewpoint of enhancing the flexibility, moldability, and appearance of the laminated foam sheet. Is 20 or less, more preferably 15 or less, and still more preferably 10 or less.

The following methods (1) and (2) may be mentioned as a method for producing a laminated foam sheet by laminating the foam sheet (A) and the resin sheet (B).
Method (1): Extrusion Laminating Method A metal roll is disposed on the surface of the roll in contact with the resin sheet (B), a rubber roll is disposed on the surface of the roll in contact with the foamed sheet (A), and between the two rolls in pressure contact with the rubber roll. A method in which extruded resin and foam are simultaneously supplied to form a laminated foam sheet.
Method (2): Thermal fusion laminating method Two metal rolls arranged in parallel are used, and a resin sheet (B) and a foamed sheet (A) are simultaneously supplied between rolls having a predetermined gap. In this case, the resin sheet (B) is heated on the foam surface to be laminated, and the foam is heated on the resin sheet surface to be laminated with a far-red heater, whereby the resin sheet (B) and the foam are thermally fused to form a laminated foam sheet. Method.

  The resin sheet (B) may be provided on only one surface of the foamed sheet (A) or may be provided on both surfaces. When a skin material is laminated on a laminated foam sheet to form a molded body, the foam sheet (A) is preferably disposed on the surface opposite to the surface in contact with the skin material.

[Molded body]
The molded body of the present invention is obtained by molding the laminated foamed sheet of the present invention by a known method. When manufacturing a molded object, other raw materials, such as a base material and a skin material, can be laminated | stacked and bonded together and manufactured.

(Base material)
The base material serves as a skeleton of the molded body, and a thermoplastic resin is usually used. As the thermoplastic resin for the substrate, the above-described polyolefin resin, a copolymer of ethylene and α-olefin, vinyl acetate, acrylic ester, ABS resin, polystyrene resin, or the like can be applied.
When laminating a base material on the laminated foamed sheet of the present invention, it is preferable to inject a base material resin on the resin sheet (B) side to integrate and laminate.
At this time, if a resin having a considerably high melting point such as a polyamide-based resin or a polybutylene terephthalate-based resin is used as the base material, the melting temperature of the base material layer becomes high, and the bubble of the foamed sheet (A) at the time of molding depends on the temperature. May be destroyed. Therefore, the melting point of the base resin is lower than the melting point of the resin constituting the resin sheet (B), in other words, the melting point of the resin constituting the resin sheet (B) is higher than the melting point of the base resin. It is preferable to select the base resin so as to be high.

(Skin material)
As the skin material, polyvinyl chloride sheet, sheet made of mixed resin of polyvinyl chloride and ABS resin, thermoplastic elastomer sheet, woven fabric, knitted fabric, non-woven fabric, artificial leather, synthetic leather, etc. using natural fiber or artificial fiber, etc. Examples include leather and metal. Moreover, it is good also as a composite molded object by which the design, such as a skin texture and a grain pattern, was given to the surface using the leather stamper etc. which attached the unevenness | transfer transferred from genuine leather, stone, wood, etc.
As a method of laminating the skin material, for example, an extrusion laminating method, an adhesive laminating method in which an adhesive is applied and then laminating, a thermal laminating method (thermal fusing method), a hot melt method, a high-frequency welder method, or electroless with metals There are a plating method, an electrolytic plating method, a vapor deposition method, and the like.

Examples of the molding method of the molded body of the present invention include a stamping molding method, a vacuum molding method, a compression molding method, and an injection molding method. Of these, the stamping molding method and the vacuum molding method are preferable. As the vacuum forming method, either a male drawing vacuum forming method or a female drawing vacuum forming method can be adopted, but the male drawing vacuum forming method is more preferable.
The molded body formed by molding the laminated foam sheet of the present invention can be used as a heat insulating material, a cushioning material, etc., but is particularly suitable as an automotive interior material such as a ceiling material, a door, an instrument panel, etc. in the automotive field. Can be used for

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited at all by these examples.
In addition, the measuring method of each physical property and the evaluation method of a foamed sheet are as follows.

(1) MFR
MFR is based on JIS K7210, polypropylene resin temperature 230 ° C, load 2.16 kgf, polyethylene resin temperature 190 ° C, load 2.16 kgf, olefin thermoplastic elastomer temperature 230 ° C, load 2.16 kgf It is a value measured by.
(2) Melting point MFR is a value measured based on JIS K0064.
(3) Density and Foaming Ratio The density (apparent density) of the foamed sheet was measured according to JISK7222.
The expansion ratio was calculated as the reciprocal of the obtained density.
(4) Crosslinking degree About 100 mg of a test piece is collected from the foamed sheet, and the mass A (mg) of the test piece is precisely weighed. Next, this test piece was immersed in 30 cm ³ of xylene at 120 ° C. and allowed to stand for 24 hours, and then filtered through a 200-mesh wire mesh to collect the insoluble matter on the wire mesh, vacuum dried, and the mass of the insoluble matter. Weigh B (mg) precisely. From the obtained value, the degree of crosslinking (% by mass) was calculated by the following formula.
Crosslinking degree (% by mass) = 100 × (B / A)
(5) Sheet thickness Measured with a dial gauge.
(6) Tensile strength Tensile strength of the foamed sheet was measured at room temperature (23 ° C.) using a tensile tester in accordance with JIS K6767 (Method A). The tensile strength is preferably larger from the viewpoint of improving the shear strength of the sheet.

Production Examples 1 to 4 and Comparative Production Examples 1 to 2 [Production of Foam Sheet (A)]
Each resin component and additive shown in Table 1 are put into a single screw extruder in the number of parts shown in Table 1, melt kneaded and extruded at a resin temperature of 190 ° C., and a sheet-like resin composition having a predetermined thickness. Got. The resin composition was cross-linked by irradiating an electron beam with 1 Mrad at an acceleration voltage of 800 kV on both surfaces of the sheet-like resin composition. Thereafter, the crosslinked resin composition was heated at 250 ° C. for 5 minutes in a hot air oven and foamed by the heating to obtain a foamed sheet having a predetermined thickness. The results are shown in Table 1.

Details of the resin components and additives shown in Table 1 are as follows.
Random PP: ethylene-propylene random copolymer, manufactured by Nippon Polypro Co., Ltd., Novatec EG7F, MFR = 1.3 g / 10 min, ethylene content: 3% by mass, melting point: 130-150 ° C.
LLDPE: linear low density polyethylene resin, product name: 2036P, manufactured by Dow Chemical Co., MFR = 2.5 g / 10 min, melting point: 110-130 ° C.
TPO: olefin-based thermoplastic elastomer, product name: CA7320A, manufactured by Sun Allomer Co., Ltd., MFR = 2.1 g / 10 min, melting point: 163 ° C.
Foaming agent: Azodicarbonamide Crosslinking aid: Trimethylolpropane trimethacrylate Antioxidant 1: 2,6-di-tert-butyl-p-cresol Antioxidant 2: Dilaurylthiodipropionate

Examples 1-1 to 4-1 and Comparative Examples 1-1 to 2-1 [Production of Laminated Foamed Sheet 1]
The foamed sheet (A) and unfoamed resin sheet (B) obtained in the above production example were hot-press molded at 180 ° C. to produce a laminated foamed sheet 1.
The following evaluation was performed using the obtained laminated foam sheet 1. The results are shown in Table 2.

<25% compression hardness>
The measurement was made according to JIS K6767, and the flexibility was determined according to the following criteria.
(Criteria)
A: 25% compression hardness is 40 kPa or more and 70 kPa or less, excellent flexibility, and sufficient mechanical strength.
B: 25% compression hardness exceeds 70 kPa, but there is no practical problem with flexibility.
C: Poor flexibility and practical problem.

<Sheet deformation amount>
The laminated foam sheet heated and press-molded on a flat plate at 180 ° C is cooled to room temperature with the resin sheet on the top surface, and the amount of warpage (height from the bottom to the end face of the laminated foam sheet whose section is deformed in an arc shape. ) Was measured with a metal scale to determine the amount of deformation.
(Criteria)
A: The deformation is 1.5 mm or less.
B: Although the deformation is 1.5 to 3.5 mm, there is no practical problem.
C: The deformation amount exceeds 3.5 mm, which is a practical problem.

From Table 2, the laminated foam sheets obtained in Examples 1-1 to 4-1 are excellent in flexibility and moldability, but the laminated foam sheet obtained in Comparative Example 1-1 is a deformation of the sheet. There was a problem in practical use.
In addition, the laminated foam sheet obtained in Comparative Example 2-1 has no problem in flexibility and deformation of the sheet, but as is clear from Comparative Example 2-2 described later, Occurrence, poor appearance, and practical problems.

Examples 1-2 to 4-2, Comparative Examples 1-2 to 2-2 [Production of Laminated Foamed Sheet 2]
After the laminated foam sheet 1 obtained in Examples 1-1 to 4-1 or Comparative Examples 1-1 to 2-1 was placed in an injection mold, a base material (random polypropylene, manufactured by Nippon Polypro Co., Ltd., Novatec BC4BSW, MFR = 5.0 g / 10 min, melting point: 135-150 ° C.), and foam sheet (A)
The laminated foamed sheet 2 was obtained by laminating in the order of / unfoamed resin sheet (B) / base material.
Using the obtained laminated foam sheet 2, the appearance was evaluated. The results are shown in Table 3.

<Appearance>
The surface appearance of the obtained laminated foamed sheet was visually observed to examine the presence or absence of a gate mark dent, and the appearance was determined according to the following criteria.
(Criteria)
A: There is almost no gate mark phenomenon, the depth of the slightly existing dent is 0.05 mm or less, and the appearance is good.
B: Although there is a slight gate mark phenomenon, the depth of the slightly existing dent is 0.1 mm or less, and the appearance is not a problem in practice.
C: The depth of the recess of the gate mark is as large as 0.2 mm or more, the appearance is bad, and this is a practical problem.

From Table 3, the laminated foam sheet 2 obtained in Examples 1-2 to 4-2 has no problem in appearance, and as is clear from Examples 1-1 to 4-1 described above, flexibility and molding It can be seen that it is excellent in properties and has established these characteristics.
On the other hand, the laminated foamed sheet obtained in Comparative Example 1-2 has no problem in appearance, but as shown in Comparative Example 1-1 described above, the laminated foamed sheet as the raw material of Comparative Example 1-2 is a sheet. This was a practical problem.
In addition, the laminated foamed sheet obtained in Comparative Example 2-2 had gate marks and was poor in appearance and practically problematic.

Claims (8)

A laminated foam sheet comprising a crosslinked polyolefin resin foam sheet (A) and an unfoamed resin sheet (B), which satisfies the following condition 1.
Condition 1: Density (g / cm ³ ) of the foamed sheet (A) × Thickness (μm) of the resin sheet (B) = 3.0 to 25 The laminated foam sheet of Claim 1 whose density of the said foam sheet (A) is 0.03-0.12 g / cm < ³ >, and whose thickness of the said resin sheet (B) is 20-300 micrometers.   The laminated foam sheet of Claim 1 or 2 whose tensile strength of the said resin sheet (B) is 11-90N.   The laminated foam sheet of any one of Claims 1-3 whose resin which comprises the said resin sheet (B) is polyolefin resin.   The laminated foam sheet according to any one of claims 1 to 4, wherein a base resin is further injected and laminated and integrated on the resin sheet (B) side.   The laminated foam sheet according to claim 5, wherein the resin constituting the resin sheet (B) has a melting point higher than that of the base resin.   The molded object formed by laminating | stacking and integrating a skin material on one surface of the lamination | stacking foam sheet of any one of Claims 1-6.   The molded article according to claim 7, which is an automobile interior material.