WO2018025343A1 - Laminate body - Google Patents

Abstract

A laminate body is made of a polyolefin resin foam (A) and skin material (B). The laminate body is characterized in that the polyolefin resin foam (A) contains 30 mass% or more and 60 mass% or less of polypropylene resin (a1), 1 mass% or more and 20 mass% or less of polyethylene resin (a2), and 30 mass% or more of thermoplastic elastomer resin (a3) in 100 mass% of polyolefin resin constituting the polyolefin resin foam (A). Thus, the laminate body produces an excellent effect of flexibility and a feeling of softness when touched, promotes easy cleavage of an air bag in the range of low temperatures to high temperatures, and, during cleavage of the air bag, does not cause the problem of scattering of some portions of the skin material or the foam, or an appearance failure in which a skin layer and a foam layer are separated. These features are obtained particularly at low temperatures.

Description

Laminated body

The present invention relates to a laminate of a suitable skin material and polyolefin resin foam in automotive interior materials such as instrument panels and door panels.

Laminates consisting of a skin material and polyolefin resin foam are generally excellent in flexibility, heat resistance, heat insulation, light weight, and good design. It is used for automotive interior materials such as industrial materials, ceilings, door panels, instrument panels. In particular, the design of the skin material and the touch and feel of softness when touching a laminate made of polyolefin resin foam, and good design are added to bring out the luxury appearance and functionality of automotive interior materials. And demand is increasing.
In automobile interior materials such as instrument panels and door panels, in order to ensure the safety of the driver and passengers when an automobile collides, there is an air bag inside the lid that has been processed, For example, when necessary, the lid is opened and the airbag is instantly inflated. Therefore, there is a case where a hole is formed or a groove is provided in the corresponding part so that the airbag easily inflates and comes out. However, since the structure in which the holes and grooves are exposed on the appearance is not preferable, the skin material and the polyolefin resin foam are bonded to the resin base material so that the processing traces such as the holes and grooves are not visible. Covering with a laminate, the exterior of the laminate is devised to conceal the grooves, thereby providing automobile interior materials with a more luxurious appearance.
In recent years, there is a desire for a laminate that achieves a high degree of flexibility and good-quality appearance and a property that facilitates breaking in the thickness direction of a laminate composed of a skin material and a polyolefin resin foam. It is rare.
However, the flexibility is improved by reducing the thickness of the skin material and increasing the expansion ratio of the polyolefin resin foam in order to facilitate the flexibility and the destruction in the thickness direction of the laminate, Since the mechanical strength is low, the laminate can be easily broken in the thickness direction, but the laminate is broken during compression molding such as vacuum molding or low-pressure injection molding, which causes a problem in appearance. Moreover, although the mechanical strength is improved by lowering the expansion ratio of the polyolefin resin foam, there is a problem that the flexibility is lowered.
As a method for solving these problems, a laminate of a polypropylene resin, a polyethylene resin, and a polyolefin resin foam in which the mixing ratio of a thermoplastic elastomer resin is regulated, and in a range from a low temperature to a high temperature region, an airbag A method that promotes easy tearing of the airbag, prevents the skin and foam from being partly scattered at the time of airbag tearing, and a method that does not cause the appearance defect that the skin layer and the foam layer peel off (see Patent Document 1). A resin, polyethylene-based resin, and thermoplastic elastomer-based material are added to obtain a crosslinked polyolefin-based resin foam with good heat resistance, flexibility and good design that enables secondary processing into complex shapes , (Meth) acrylic acid ester of methyl methacrylate and alcohol having 2 to 8 carbon atoms to thermoplastic polyurethane and acrylic soft resin. A high-grade product with a complex, sharp corner shape that creates a flexible feel by integrating a sheet-shaped molding compound containing stealth and calcium carbonate with a base material via polyurethane foam and polypropylene foam. Has been proposed (see Patent Document 2 and Patent Document 3).
Furthermore, as a skin material for an automobile airbag, a skin layer made of a thermoplastic resin layer and a two-layer structure made of a polyolefin foam layer, or a skin layer made of a thermoplastic resin layer, a polyolefin foam layer, polypropylene, etc. It has also been proposed to improve the appearance of the airbag storage part and facilitate the inflation of the airbag by allowing the skin material to have a needle hole that cannot be visually confirmed using a three-layer structure consisting of the barrier layer. (See Patent Document 4).

JP 2014-172307 A JP 2008-266589 A Japanese Patent No. 3864330 Japanese Patent Laid-Open No. 10-44908

However, in a laminate of a polypropylene resin, a polyethylene resin, and a foam using a thermoplastic elastomer resin, the polyolefin resin foam is susceptible to brittle fracture in the low temperature region. Further, there is a possibility that one part of the foam is scattered and the strength of the laminated body is temporarily increased, and the airbag may not be easily opened.
Furthermore, it is not easy to process a needle hole that cannot be visually confirmed on the skin material. If the needle hole is enlarged, there is a problem in appearance, and if it is too small, the effect may be limited.
The present invention is suitable for instrument panels, door panels, and the like, and is excellent in flexibility and soft touch, and aims to promote easy tearing of an airbag in a range from a low temperature to a high temperature region. .
Another object of the present invention is to solve the problem that one part of the skin material and the foam is scattered at the time of air bag tearing and the problem that the appearance defect that the skin layer and the foam layer are separated does not occur.

To achieve the above object, the present invention has the following configuration.
The polyolefin resin foam (A) used in the laminate of the present invention is composed of 30% by mass to 60% by mass of the polypropylene resin (a1) and 100% by mass of the polyethylene resin (a2) in 100% by mass of the polyolefin resin. 1 mass% or more and 20 mass% or less and 30 mass% or more of thermoplastic elastomer-type resins (a3).
According to a preferred aspect of the laminate of the present invention, the tensile elongation of the laminate is 30% or more under a temperature environment at −35 ° C.
According to a preferred embodiment of the laminate of the present invention, the laminate is a laminate of a polyolefin resin foam (A) and a skin material (B), and the polyolefin resin foam (A) is a differential scanning calorimeter. (DSC) has an endothermic peak in the region of 100 ° C. or higher and 130 ° C. or lower and 145 ° C. or higher
The skin material (B) has at least one endothermic peak by a differential scanning calorimeter (DSC) in a region of 95 ° C. or higher and 110 ° C. or lower and each region of 130 ° C. or higher and 160 ° C. or lower.
The preferable aspect of the laminated body of this invention is an automotive interior material use.

In the laminate of the present invention, when used as an automobile interior material equipped with a resin base material having an airbag storage structure, that is, in applications such as instrument panels and door panels, flexibility when contacting the laminate, and It has an excellent effect on the tactile sensation of feeling softness, and facilitates easy tearing of the airbag in a range from a low temperature to a high temperature region.
Further, when the airbag is torn, the problem that one part of the skin material and the foam is scattered and the appearance defect that the skin layer and the foam layer are peeled off are not caused, and the characteristics are exhibited particularly in a low temperature region.

Hereinafter, the present invention will be specifically described.

The present invention is a laminate of a polyolefin resin foam (A) and a skin material (B), wherein the polyolefin resin foam (A) constitutes the polyolefin resin foam (A). In 100% by mass of the resin, 30% by mass to 60% by mass of the polypropylene resin (a1), 1% by mass to 20% by mass of the polyethylene resin (a2), and 30 of the thermoplastic elastomer resin (a3). It contains at least mass%.

In 100% by mass of polyolefin resin, 30% to 60% by mass of polypropylene resin (a1), 1% to 20% by mass of polyethylene resin (a2), thermoplastic elastomer resin (a3) If it contains 30% by mass or more, it has an excellent effect on the softness and touch feeling when touching the laminate, and particularly in a low temperature region, one part of the skin material or foam is present when the airbag is opened. The problem of scattering and the appearance defect that the skin layer and the foam layer are peeled off can be prevented.

The polyolefin resin foam (A) used in the laminate of the present invention must be composed of at least a polypropylene resin (a1), a polyethylene resin (a2), and a thermoplastic elastomer resin (a3). .
Examples of the polypropylene resin (a1) include homopolypropylene, ethylene-propylene random copolymer, and ethylene-propylene block copolymer. Copolymerization of propylene monomer with other copolymerizable monomers as necessary. A polymer can also be used. The polypropylene resin (a1) may be used alone or in a blend of two or more. Moreover, there is no restriction | limiting in particular in the polymerization method of these polypropylene resin (a1), Any of a high pressure method, a slurry method, a solution method, and a gaseous phase method may be sufficient, and also about a polymerization catalyst, such as a Ziegler catalyst and a metallocene catalyst, especially. It is not limited.
The polypropylene resin (a1) has an ethylene-propylene random copolymer and an ethylene-propylene random copolymer having a melting point of 135 ° C. or more and less than 160 ° C. and an MFR (230 ° C.) of 0.5 g / 10 min or more and less than 5.0 g / 10 min. A block copolymer having an ethylene content of 1% by mass or more and less than 15% by mass in 100% by mass of the polypropylene resin (a1), or a melting point of 150 ° C. or more and less than 170 ° C. and an MFR (230 ° C.) of 1. An ethylene-propylene block copolymer or homopolypropylene having an ethylene content of 1% by mass or more and less than 15% by mass of 0 g / 10 min or more and less than 7.0 g / 10 min is particularly preferably used. The “block” of the ethylene-propylene random block copolymer and the ethylene-propylene block copolymer here means that ethylene-propylene rubber is mixed with the ethylene-propylene random copolymer or homo-polypropylene. This is different from the block structure in general polymer chemistry.

Examples of the polyethylene resin (a2) include high density polyethylene (HDPE), low density polyethylene (LDPE), linear low density polyethylene (LLDPE), ethylene-ethyl acrylate copolymer (EEA), and ethylene-butyl acrylate. A polymer (EBA) etc. are mentioned, The copolymer of an ethylene monomer and another copolymerizable monomer can also be used as needed. In addition, the polyethylene resin (a2) may be a single type or a blend of two or more types. Further, the polymerization method of these polypropylene resins is not particularly limited, and any of a high pressure method, a slurry method, a solution method, and a gas phase method may be used, and the polymerization catalyst is particularly limited, such as a Ziegler catalyst or a metallocene catalyst. It is not a thing.
As the polyethylene resin (a2), those having a density of 890 to 950 kg / m ³ and an MFR (190 ° C.) in the range of 1 g / 10 min to less than 15 g / 10 min are preferably used, and in particular, the density is 920 to 940 kg / m. ^3. An ethylene-α-olefin copolymer having an MFR (190 ° C.) of 2 g / 10 min or more and less than 10 g / 10 min and a melting point of 100 ° C. or more and less than 130 ° C. is particularly preferably used.
Examples of the thermoplastic elastomer-based resin (a3) include polystyrene-based thermoplastic elastomer (SBC, TPS), polyolefin-based thermoplastic elastomer (TPO), vinyl chloride-based thermoplastic elastomer (TPVC), and polyurethane-based thermoplastic elastomer (TPU). , Polyester-based thermoplastic elastomers (TPEE, TPC), polyamide-based thermoplastic elastomers (TPAE, TPA), polybutadiene-based thermoplastic elastomers, hydrogenated styrene butadiene rubber (HSBR), styrene / ethylene butylene / olefin crystal block polymer (SEBC) , Olefin Crystal / Ethylene Butylene / Olefin Crystal Block Polymer (CEBC), Styrene / Ethylene Butylene / Styrene Block Polymer (SEBS), Olefin Block Block copolymers such as polymers (OBC) and polyolefin-vinyl graft copolymers, polyolefin-amide graft copolymers, polyolefin-acrylic graft copolymers, and polyolefin-cyclodextrin graft copolymers, and particularly preferred are olefin block copolymers (OBC) or polyolefin-based thermoplastic elastomer (TPO). Among these, both heat resistance and flexibility are preferably high, and from this viewpoint, olefin block copolymer (OBC) is particularly preferable. These thermoplastic elastomer resins (a3) may be blended in at least one kind or two or more kinds. Moreover, there is no restriction | limiting in particular in the polymerization method of these thermoplastic elastomer type-resins (a3), Any of a high pressure method, a slurry method, a solution method, and a gaseous phase method may be sufficient, and also about a polymerization catalyst, a Ziegler catalyst, a metallocene catalyst, etc. There is no particular limitation.
The thermoplastic elastomer resin (a3) has a melting point of 150 ° C. or higher and a crystal melting energy of less than 30 J / g from the viewpoint of excellent heat resistance and moldability. If the melting point is less than 150 ° C., the required heat resistance may not be sufficiently obtained, and if the crystal melting energy is 30 J / g or more, the crystallinity is high and sufficient flexibility may not be obtained. There is sex. More preferably, the melting point is 160 ° C. or higher, and the crystal melting energy is less than 25 J / g. Further, the crystallization temperature is preferably 50 ° C. or higher. More preferably, it is 60 degreeC or more. If the crystallization temperature is less than 50 ° C., the cycle time when molding the foam may not be shortened.
The glass transition temperature of the thermoplastic elastomer resin (a3) is preferably less than −20 ° C., more preferably less than −30 ° C., and most preferably less than −40 ° C. When the glass transition temperature is −40 ° C. or higher, the desired flexibility may not be obtained, which may adversely affect the airbag deployment characteristics at low temperatures that the present invention intends to achieve.
The thermoplastic elastomer resin (a3) preferably has a density of 850 to 920 kg / m ³ and an MFR (230 ° C.) in the range of 1 g / 10 min to less than 15 g / 10 min. Those having 910 kg / m ³ and MFR (230 ° C.) of 5 g / 10 min or more and less than 10 g / 10 min are particularly preferably used. Examples of commercially available thermoplastic elastomer resins (a3) used in the present invention include Mitsui Chemicals “Toughmer” (registered trademark) PN-3560, polyolefin-based thermoplastic elastomer (TPO) as olefin block copolymer (OBC). Includes "Prime TPO" (registered trademark) M142E manufactured by Prime Polymer.
The polyolefin resin foam (A) used in the laminate of the present invention may be mixed with other thermoplastic resins as long as the effects of the invention are not impaired. Examples of the thermoplastic resin herein include conventionally known polyester, polyamide, polylactic acid, polyether, polyvinyl chloride, polyurethane, polystyrene and the like.

In the polyolefin-based resin foam (A) used in the laminate of the present invention, phenolic, phosphorus-based, amine-based and sulfur-based antioxidants, and metal damage prevention are within the range not impairing the effects of the present invention. Additives, fillers such as mica and talc, flame retardants such as bromine and phosphorus, flame retardant aids such as antimony trioxide, antistatic agents, lubricants, pigments, and polyolefin additives such as polytetrafluoroethylene Can be added.

The polyolefin resin foam used in the laminate of the present invention is produced by mixing a polyolefin resin mixture with a foaming agent capable of generating gas, and the production method thereof is a polyolefin resin mixture. In addition, as a foaming agent, a pyrolytic chemical foaming agent is added and melt kneaded, and then the normal pressure foaming method in which foaming is performed by heating at normal pressure. The pyrolytic chemical foaming agent is thermally decomposed in an extruder and extruded under high pressure. Extrusion foaming while foaming, heat decomposable chemical foaming agent is thermally decomposed in a press mold, press foaming method foaming while reducing pressure, and gas or vaporized solvent is melted and mixed in an extruder and extruded under high pressure Examples thereof include an extrusion foaming method for foaming.

The thermal decomposition type chemical foaming agent used here is a chemical foaming agent that decomposes by applying heat and releases a gas. For example, azodicarbonamide, N, N′-dinitrosopentamethylenetetramine, P, P Examples thereof include organic foaming agents such as' -oxybenzenesulfonylhydrazide, and inorganic foaming agents such as sodium bicarbonate, ammonium carbonate, ammonium bicarbonate, and calcium azide.

A foaming agent can be used individually or in combination of 2 types or more, respectively. In order to obtain a high-magnification foam that is flexible and has high moldability and a smooth surface, a normal pressure foaming method using azodicarbonamide as a foaming agent is preferably used.
The polyolefin resin foam (A) used in the laminate of the present invention has a thickness of 0.50 mm to 5.0 mm. When the laminate of the present invention is used as an automobile interior material, the thickness of the polyolefin resin foam is preferably 1.0 mm or more and 4.0 mm or less, and promotes destruction in a low temperature environment of −40 to −10 ° C. Considering this, a more preferable aspect is a range of 2.0 mm to 3.0 mm.

The polyolefin resin foam used in the laminate of the present invention preferably has an apparent density in the range of 30 kg / m ³ or more and 150 kg / m ³ or less from the viewpoint that both moldability and flexibility are excellent. When the laminate of the present invention is used for an automobile interior material, a more preferable embodiment is a range of 50 kg / m ³ or more and 100 kg / m ³ or less.
The polyolefin-based resin foam used in the laminate of the present invention can be either a crosslinked resin foam (referred to as a crosslinked foam) or an uncrosslinked resin foam (referred to as a non-crosslinked foam). What is necessary is just to select a suitable resin foam according to a use. However, since the surface of the resin foam has smoothness and the appearance of the laminate is excellent, and because it is difficult to break at the time of molding, the design can be pursued. preferable.
There is no restriction | limiting in particular in the method for making the said polyolefin resin foam (A) into a crosslinked foam. As a method for obtaining a crosslinked foam, for example, a chemical crosslinking method in which a raw material contains a crosslinking agent having a chemical structure such as a silane group, a peroxide, a hydroxyl group, an amide group, and an ester group, Examples thereof include a radiation crosslinking method in which electron beams, α rays, β rays, γ rays, and ultraviolet rays are irradiated to a polyolefin resin for crosslinking. Polyolefin-based because the foam cells are made uniform and the destruction of the laminate is promoted in a low temperature environment of −40 ° C. to −10 ° C., and the surface appearance of the foam is smoothed and the appearance of the laminate is excellent. In order to make the resin foam (A) into a crosslinked foam, radiation crosslinking with an electron beam is preferred.
Moreover, in the polyolefin resin foam (A) used for the laminate of the present invention, when it is difficult to construct a crosslinked structure by electron beam crosslinking, the polyolefin resin foam (A) is produced. By containing a crosslinking aid in the raw material, a crosslinked foamed body by an electron beam can be obtained. Although there is no restriction | limiting in particular as a crosslinking adjuvant, It is preferable to use a polyfunctional monomer. Examples of the polyfunctional monomer include divinylbenzene, trimethylolpropane trimethacrylate, 1,6-hexanediol dimethacrylate, 1,9-nonanediol dimethacrylate, 1,10-decanediol dimethacrylate, trimellitic acid triallyl ester , Triallyl isocyanurate, ethyl vinyl benzene and the like can be used. These polyfunctional monomers may be used alone or in combination of two or more.
When the polyolefin resin foam (A) used in the laminate of the present invention is crosslinked, that is, when the foam of the present invention is a crosslinked foam, the gel fraction indicating the crosslinked state is 20% or more and 65%. It is preferable that it is the following range, Furthermore, it is preferable that it is the range of 30% or more and 50% or less. If the gel fraction is less than 20%, the foaming agent gas is dissipated from the foaming surface, making it difficult to obtain a product with the desired expansion ratio. On the other hand, if the gel fraction exceeds 65%, excessive crosslinking occurs. It may be difficult to obtain a product with a high surface expansion ratio and a high expansion ratio, and mechanical strength such as elongation at break may be lowered, and moldability may be lowered.
The polyolefin resin foam (A) used in the laminate of the present invention preferably has a 25% compression hardness of 30 kPa or more and 120 kPa or less, more preferably 50 kPa or more and 100 kPa or less as an index indicating flexibility. It is an aspect.
The polyolefin resin foam (A) used in the laminate of the present invention preferably has two or more endothermic peaks in the differential scanning calorimetry. Specifically, it is preferable that endothermic peaks by a differential scanning calorimeter (DSC) exist at 100 ° C. or higher and 130 ° C. or lower and 145 ° C. or higher. The first endothermic peak is more preferably 110 ° C. or more and less than 125 ° C., the second endothermic peak is more preferably 150 ° C. or more, and most preferably 155 ° C. or more. When the first endothermic peak is 130 ° C. or higher, the softening temperature at the time of molding the laminate may be too high, and the molding cycle may be too long. When the second endothermic peak is less than 145 ° C. In the current situation where the heating rate tends to be increased in order to increase the molding temperature, heat resistance is often insufficient.
The total crystal melting energy per unit mass in the differential scanning calorimetry of the polyolefin resin foam (A) used in the laminate of the present invention is preferably less than 80 J / g. When it is 80 J / g or more, there are many crystal components, and the flexibility to be achieved by the present invention may not be sufficiently obtained. More preferably, it is less than 70 J / g.
The polyolefin resin foam (A) used for the laminate of the present invention preferably has a crystal melting energy per unit mass of 145 ° C. or higher of less than 20 J / g. When it is 20 J / g or more, a large amount of propylene-based resin may be contained, and in that case, sufficient flexibility that is the object of the present invention may not be obtained.
The polyolefin resin foam (A) used in the laminate of the present invention preferably has a heat shrinkage of less than 40% at 180 ° C. for 10 minutes. If it is 40% or more, it shrinks at the time of vacuum forming, so when trying to obtain a molded body of a predetermined size, more materials are required, the yield deteriorates, and more skin materials are required. Economic disadvantage.
The molding draw ratio of the polyolefin resin foam (A) used in the laminate of the present invention is preferably 0.4 or more and less than 0.8. If it is less than 0.4, there is insufficient moldability, and tearing may occur during shaping. On the other hand, if it is 0.8 or more, there is a possibility that deviation from the skin material when the laminate is formed is not preferable. More preferably, it is 0.5 or more and less than 0.7.
The polyolefin resin foam (A) used in the laminate of the present invention preferably has a closed cell structure. In the case of a foam having a closed cell structure, it is possible to form a complicated shape, for example, air can be sufficiently drawn by vacuum forming because of the structure. Moreover, it is preferable that the bubbles are fine and uniform since the surface of the foam or a molded product obtained by molding the foam becomes smooth.
It is preferable that the polyolefin resin foam (A) used for the laminate of the present invention can be produced in the form of a long sheet. By making it into a long sheet shape, it is possible to supply a large amount at a low cost.
There is no restriction | limiting in particular in the thermoplastic resin which comprises the skin material (B) which comprises the laminated body of this invention. Examples of the thermoplastic resin constituting the skin material (B) include polyethylene, polypropylene, ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer (EEA), and ethylene-butyl acrylate copolymer. (EBA), thermoplastic polyolefin elastomer (TPO) containing an elastomer component such as ethylene-propylene rubber, vinyl resin such as polyvinyl chloride and polyvinylidene chloride, polyurethane resin, polystyrene resin, polyether resin, polyamide resin, And copolymers composed of monomers copolymerizable with these resins. The thermoplastic resin constituting these skin materials (B) may be mixed with at least one or two or more.
The thermoplastic resin constituting the skin material (B) preferably has at least an endothermic peak by a differential scanning calorimeter in a region of 95 ° C. or higher and 110 ° C. or lower and a region of 130 ° C. or higher and 155 ° C. or lower. The skin material (B) preferably has at least an endothermic peak by a differential scanning calorimeter in a region of 95 ° C. or higher and 110 ° C. or lower and a region of 130 ° C. or higher and 155 ° C. or lower.
In addition, for the purpose of improving processability and appearance, inorganic fillers, antioxidants, hydrocarbon oils and the like may be added. Particularly, when the skin material (B) contains a block copolymer elastomer having a polyolefin hard segment and a polyolefin soft segment, and contains a polyolefin resin, such as a thermoplastic polyolefin elastomer, Lamination processing with the polyolefin resin foam (A) is simplified, and it is preferable because of its flexibility when contacted.
The thickness of the skin material (B) which comprises the laminated body of this invention is not specifically limited, It can process and use for the thickness according to the intended purpose. The thickness of the skin material (B) is preferably in the range of 0.1 mm to 1.5 mm. In consideration of promoting the destruction in a low temperature environment of −40 to −10 ° C., the thickness of the skin material (B) is preferably 0.3 mm or more and 0.6 mm or less.
There is no restriction | limiting in the method of laminating | stacking the polyolefin resin foam (A) and skin material (B) of this invention. The surface of the polyolefin resin foam (A) or skin material (B) that contacts the adhesive is subjected to electrical discharge machining, and hydroxyl groups are introduced into the surface to improve the adhesion. Or a urethane-based solvent-based adhesive or an emulsion-based adhesive may be applied to the polyolefin-based resin foam (A) and bonded together. Specific examples of the adhesive include “Pandex T-5265” manufactured by Dainippon Ink & Chemicals, Inc. and “Desmocol # 500” manufactured by Bayer Co., Ltd. As other methods, a heat-sealing method of heating and laminating the polyolefin resin foam (A) and the skin material (B) is preferably used.
The laminate of the present invention preferably has a tensile elongation of 30% or more under an environment of −35 ° C. If the tensile elongation of the laminate under an environment of −35 ° C. is less than 30%, the polyolefin resin foam (A) is scattered when the airbag is opened, which is not preferable. The tensile elongation at the time when the polyolefin resin foam (A) and the skin material (B) were peeled off at the interface or the material in the environment of −35 ° C. in the environment of −35 ° C. It is preferably 30% or more in both directions (MD direction) and orthogonal direction (hereinafter referred to as TD direction).
Moreover, it is preferable that the laminated body of this invention is 20 N / 25mm or more in the maximum peeling strength of the interface peeling between a polyolefin-type resin foam (A) and a skin material (B) or material fracture peeling. If the maximum peel strength of interfacial peeling or material breakage peeling is less than 20 N / 25 mm, the polyolefin resin foam (A) and the skin material (B) peel off and cause poor appearance when broken. There is a concern that a part of the resin-based resin foam (A) or the skin material (B) may be scattered. Especially in automobile interior materials equipped with airbags, when the polyolefin resin foam (A) is peeled off from the skin material (B) due to the impact of the airbag destroying the laminate, only the polyolefin resin foam (A) is produced. There is a concern that the skin material (B) breaks, and the skin material (B) does not break, and the speed at which the airbag is cleaved is slow. It is preferable that the maximum peel strength of interfacial delamination or material delamination between the polyolefin resin foam (A) and the skin material (B) of the laminate is 25 N / 25 mm or more. In addition, the maximum peeling strength of interfacial peeling or material breaking peeling between the polyolefin resin foam (A) and the skin material (B) of the laminate of the present invention is 20 N / 25 mm or more in both the MD direction and the TD direction. It is preferable that
The upper limit of the maximum peel strength between the polyolefin resin foam (A) and the skin material (B) of the present invention is not limited, but is preferably 150 N / 25 mm or less.
When using the laminated body of this invention as a motor vehicle interior material, there is no restriction | limiting in particular in the adhesive agent which adhere | attaches a laminated body and a resin base material. For example, “Pandex T-5265” manufactured by Dainippon Ink and Chemicals, “Desmocol # 500” manufactured by Bayer Co., Ltd. can be used as an adhesive on the polyolefin resin foam side.
The difference in low temperature tensile elongation between the polyolefin resin foam (A) and the skin material used in the laminate of the present invention is preferably less than 150%. More preferably, it is 10% or more and less than 100%, More preferably, it is 25% or more and less than 80%. If it is 150% or more, if the airbag deployment occurs at a low temperature, the foam and skin material will be broken at different timings, causing more severe delamination at the interface, resulting in foam scattering. It is a problem.
The automobile interior material comprising the laminate of the present invention generally has at least three layers of a skin material (B), a polyolefin resin foam (A), and a resin base material.
The composition of the resin base material used for the automobile interior material in the present invention is not particularly limited, and includes polypropylene resin, ABS resin, polycarbonate resin, talc, mica, wollastonite, glass beads, glass fiber, carbon fiber and the like. It is common to use a composite reinforced with an inorganic filler.
In the automobile interior material comprising the laminate of the present invention, the molding method is not limited, but generally, the above-mentioned laminate of polyolefin resin foam (A) and skin material (B) is extruded. Polyolefin resin foam (A) by producing a molded product of a laminate that becomes the shape of the interior material by a known molding process such as vacuum molding, stamping molding, blow molding, etc., and interposing an adhesive or a heat medium And a resin base material are bonded. These moldings may be subjected to secondary processing into a shape as required by thermal welding, vibration welding, ultrasonic welding, laser welding, or the like.
When the laminate of the present invention is laminated on a resin base material having an airbag function of an automobile interior material, in order to promote the tearing of the airbag, a punching machine or the like is used so long as the appearance of the skin material (B) is not deteriorated. A laser machine can be used to have holes. The holes in the resin base material and the polyolefin resin foam (A) are preferably opened in the direction from the resin base material side to the skin material (B) side so that the airbag can be more easily cleaved.

Next, the method for producing the foam of the present invention will be described by way of example.

A thermal decomposable foaming agent such as azodicarbonamide is further added to the polypropylene resin (a1), polyethylene resin (a2), and thermoplastic elastomer resin (a3), and a mixing device such as a Henschel mixer or tumbler is used. Mix evenly. Then, using melt-kneading equipment such as an extruder or a pressure kneader, melt and knead uniformly below the decomposition temperature of the pyrolytic foaming agent, and after forming into a sheet shape with a T-type die, irradiate with ionizing radiation. Crosslink.
Next, the temperature of the obtained sheet is raised above the decomposition temperature of the pyrolytic foaming agent by the method of floating on a salt bath as a heat medium or the method of throwing it in an atmosphere such as hot air. By foaming with the generated gas, the polyolefin resin foam (A) of the present invention can be obtained.

Next, the manufacturing method of the skin material of this invention is illustrated and demonstrated.
The thermoplastic resin constituting the skin material (B) is melt-kneaded using a melt-kneading device such as an extruder or a pressure kneader, and is molded into a sheet shape with a T-type die or a calender roll to a predetermined thickness To control. The obtained sheet having a predetermined thickness is air-cooled or water-cooled to obtain the skin material (B).

Next, the manufacturing method of the laminated body of this invention is illustrated and demonstrated.
With respect to the maximum temperature obtained from the endothermic peak, the surface side of the polyolefin resin foam (A) obtained by the foam production method and the skin material (B) obtained by the skin material production method is laminated. Heat to −10 ° C. to + 10 ° C. within the range of −0.3 mm or more and −1.5 mm or less than the sum of the thickness of the skin material (B) and the thickness of the polyolefin resin foam (A). A laminated body having a three-layer structure is obtained by a heat-sealing method through a nip roll whose gap is adjusted.

The evaluation methods used in the following examples and comparative examples are as follows.

(1) MFR of polyolefin resin:
MFR of polyolefin resin means JIS K7210 (1999) “Plastics – Test methods for melt mass flow rate (MFR) and melt volume flow rate (MVR) of thermoplastics”. The polyethylene resin (a2) has a temperature of 190 ° C. and a load of 2.16 kgf, the polypropylene resin (a1) and the thermoplastic elastomer resin (a3) have a temperature of 230 ° C. and a load of 2 Using a melt mass flow rate meter (melt indexer model F-B01 manufactured by Toyo Seiki Seisakusho Co., Ltd.) under the condition of .16 kgf, the manual cut-off method was adopted, and the weight of the resin that came within 10 minutes from the die was measured.

(2) Density of polyolefin resin:
The density of the polyolefin resin was measured according to JIS K7112 (1999) “Plastics—Method of measuring density and specific gravity of non-foamed plastic”.

(3) Melting point, crystallization temperature and glass transition temperature of the resin constituting the polyolefin resin foam (A) and the skin material (B):
In the present invention, the melting point of the polyolefin resin is the maximum obtained from the endothermic peak of the DSC curve obtained when the vertical axis obtained by differential scanning calorimetry is calorie (J / g) and the horizontal axis is temperature. Temperature. 2 mg of each sample was prepared using a differential scanning calorimeter (DSC: RDC220-Robot DSC manufactured by Seiko Denshi Kogyo Co., Ltd.) and measured in a nitrogen environment. The measurement conditions were that the sample was heated to a temperature of 200 ° C. and melted, and then the exothermic peak obtained when cooled to a temperature of −100 ° C. at a rate of 10 ° C./min was the crystallization temperature. The glass transition temperature is the middle point of the step-like displacement point. Then, the temperature was increased at a rate of 10 ° C./min, and the endothermic peak per unit mass was measured. The endothermic peak obtained at the second temperature increase was taken as the melting point.

(4) Foam thickness:
The thickness of the foam is a value measured in accordance with ISO 1923 (1981) “Method for measuring foamed plastic and rubber alignment”. Specifically, using a dial gauge with a circular probe having an area of 10 cm ² , the foam cut to a certain size was allowed to stand on a flat table and then contacted with the foam surface at a certain pressure. And measure.

(5) Apparent density of foam:
The apparent density of the foam is a value measured and calculated according to JIS K6767 (1999) “Foamed plastics-polyethylene test method”. The thickness of the foam cut into 10 cm square is measured, and the mass of the test piece is weighed. The value obtained by the following equation is the apparent density, and the unit is kg / m ³ .

Apparent density (kg / m ³ ) = {Test piece mass (kg) / Test piece area 0.01 (m ² ) / Test piece thickness (m)}
(6) Gel fraction of foam:
The foam is cut into about 0.5 mm squares, and about 100 mg is weighed to the nearest 0.1 mg. After being immersed in 200 ml of tetralin at a temperature of 130 ° C. for 3 hours, it is naturally filtered through a 100 mesh stainless steel wire mesh, and the insoluble matter on the wire mesh is dried in a hot air oven at 120 ° C. for 1 hour. Next, the mixture is cooled in a desiccator containing silica gel for 10 minutes, the mass of this insoluble matter is accurately weighed, and the gel fraction of the foam is calculated as a percentage according to the following formula.
Gel fraction (%) = {mass of insoluble matter (mg) / weight of weighed foam (mg)} × 100.

(7) 25% compression hardness of the foam:
The 25% compression hardness of the foam is a value measured based on JIS K6767 (1999) “Foamed plastics-polyethylene test method”. Specifically, the foam is cut into 50 mm × 50 mm, stacked so that the thickness is 20 mm or more and 30 mm or less, and the initial thickness is measured. A sample was placed on a flat plate, and stopped by compressing at a speed of 10 mm / min up to 25% of the initial thickness, the load after 20 seconds was measured, and 25% compression hardness (kPa) was calculated by the following formula.
25% compression hardness (kPa) = 25% compression and load (N) / 25 (cm ² ) / 10 after 20 seconds.

(8) Method for measuring foam by differential scanning calorimeter:
In the present invention, the endothermic peak of the foam means a peak on the endothermic side in the DSC curve obtained when the vertical axis obtained by differential scanning calorimetry is calorie (J / g) and the horizontal axis is temperature. Specifically, after foam bubbles are crushed with a mixing roll or the like in advance, about 2 mg of a test piece is weighed, and a differential scanning calorimeter (DSC: RDC220-Robot DSC, manufactured by Seiko Denshi Kogyo Co., Ltd.) is used to measure nitrogen. Measured in the environment. The measurement conditions were that the sample was heated to a temperature of 200 ° C. and melted, cooled to a temperature of −50 ° C. at a rate of 10 ° C./min, and then heated again at a rate of 10 ° C./min. Get a curve. The peak obtained from the DSC curve obtained at the second temperature increase is called an endothermic peak. The total crystal melting energy is calculated by the area surrounded by the DSC curve and the baseline at this time. Further, the endothermic amount per unit mass of 130 ° C. or higher is calculated by the area of the portion higher than this temperature by further dividing the portion surrounded by the DSC curve and the base line by a 130 ° C. line. .

(9) Measuring method of heat shrinkage rate of foam:
As a method for measuring the heat shrinkage rate, it is carried out according to JIS K6767 (1999) “Foamed plastic-polyethylene test method”. Specifically, a test piece with a 100 mm square marked line was left in a hot air oven adjusted to 180 ° C. for 10 minutes, and the amount of decrease in the distance between marked lines was divided by the original distance between marked lines of 100 mm. It is a value expressed as a percentage of the thing.

(10) Measuring method of molding drawing ratio of foam:
Molding ratio means that when a foam is heated and straight molded using a vacuum molding machine on a vertical cylindrical female mold with a diameter D and depth H, the foam does not break and expands into a cylindrical shape. It is the value of H / D at the limit of elongation.

(11) Tensile test method of foam or skin material at high and low temperatures:
A specimen sample punched out into a dumbbell shape No. 1 was placed in a thermostatic bath for 6 minutes, at a high temperature of 160 ° C., at a low temperature of −20 ° C., and then at a test speed of 500 mm / min at JIS K6767 ( 1999) Tensile tests were conducted in accordance with “Foamed Plastics—Polyethylene—Test Method” to obtain the maximum value of tensile strength and the value of tensile elongation at the time of failure.
Equipment: Tensilon UCT-500 (Orientec Corporation)
Tensile speed: 500 mm / min
(12) Tensile strength and elongation of laminate at −35 ° C .:
A specimen sample of the laminate cut in both the MD and TD directions was placed in an environment of −35 ° C. for 10 minutes, and then at a test speed of 500 mm / min, JIS K6767 (1999) “Foamed plastics—polyethylene— A tensile test was performed in accordance with “Test method”, and the maximum value of tensile strength and the value of tensile elongation at the time of failure were obtained.
Equipment: Tensilon UCT-500 (Orientec Corporation)
Tensile speed: 500 mm / min
The obtained numerical values of tensile strength and tensile elongation are average values obtained from the values measured twice.

(13) Maximum peel strength of the laminate In both the MD direction and the TD direction, a test piece sample of the laminate cut to 150 mm × 25 mm is subjected to a tensile speed of 200 mm / min, a peel angle of 180 °, and a peel distance of 80 mm. The value of the maximum peel strength when a peel test based on JIS Z 0237 (2009) was performed was determined. The measurement temperature is 23 ° C. and the humidity is 50% RH.
Equipment: Tensilon UCT-500 (Orientec Corporation)
Tensile speed: 200 mm / min
The obtained peel strength is a maximum peel strength value within a peel distance of 80 mm, and is an average value obtained from a value measured twice.

(14) Flexibility evaluation of laminate:
The stroke length when the laminate 100 mm × 100 mm was compressed from the skin material (B) side was evaluated in five stages as follows.
〔test conditions〕
Apparatus: Handy compression tester “KES-G5” manufactured by Kato Tech Co., Ltd.
Measurement environment: 23 ° C
Measurement conditions: Stroke length when compressed 1 kg (mm)
Compression speed: 1.5mm / sec
5: 1.31mm or more 4: 1.01-1.30mm
3: 0.71 to 1.00 mm
2: 0.41 to 0.70 mm
1: 0.40 mm or less.

(15) Formability Evaluation of Laminate The sensory evaluation index is shown below for the moldability evaluation of the laminate. Specifically, the cylindrical mold of (10) is used, the laminate (foam is on the bottom surface, and the skin material is on the top surface) is heated until the surface temperature reaches 160 ° C, and straight molding is performed using a vacuum molding machine. Then, the quality was judged by observing the appearance, particularly the surface of the skin material. Moreover, about the touch, the surface material side surface was similarly pushed with the finger, and the quality determination was performed.
5: Sufficient flexibility remains as a touch, and the appearance is beautiful and excellent.
4: The touch remains flexible, and the appearance is free from defects such as dents.
3: Although there is no problem with the appearance, the feel is less flexible, or the feeling of bottoming is felt or there is no problem with the touch, but there are some defects in appearance.
2: Either the feeling of flexibility is not felt or a large defect is generated in appearance, and the state is extremely poor.
1: A state in which the feel and appearance are remarkably inferior and cannot be endured as a product.

(16) Comparison of tensile elongation at low temperature between the skin material and foam in the laminate Of the tensile test of the skin material and foam performed in (11), the MD direction and TD direction at low temperature (−20 ° C.) The average value of the tensile elongation was evaluated in five stages from the numerical values obtained when the following formula was used. The indicators are shown below.

Average value of low temperature tensile elongation of skin material (%)-Average value of low temperature tensile elongation of foam (%)
5: Less than 200% 4: 200% or more and less than 230% 3: 230% or more and less than 260% 2: 260% or more and less than 290% 1: 290% or more.

(17) Comprehensive evaluation Comprehensive evaluation was performed based on the following indices based on the results of five-stage evaluation of flexibility evaluation, formability evaluation, and low-temperature tensile elongation comparison evaluation, and Δ or higher was regarded as acceptable.
A: Total is 13 or more. O: Total is 11 or more and less than 13. Δ: Total is 9 or more and less than 11. X: Total is less than 9.

Resins used in Examples and Comparative Examples are as follows.
<Polypropylene resin (a1)>
PP1: "Prime Polypro" (registered trademark) J452HAP made by Prime Polymer
Density: 900 kg / m ^3, MFR (230 ° C.) = 3.5 g / 10 min, melting point = 163 ° C.
PP2: Nippon Polypro's “NOVATEC” (Registered Commercial Code) PP EG8B
Density: 900 kg / m ³ , MFR (230 ° C.) = 0.8 g / 10 min, melting point = 140 ° C.
<Polyethylene resin (a2)>
PE1: "Novatec" (registered trademark) LL UJ960 made of Japanese polyethylene
Density: 935 kg / m ³ , MFR (190 ° C.) = 5 g / 10 min, melting point = 126 ° C.
PE2: Nippon Polyethylene "NOVATEC" (Registered Commercial Code) LD LJ602
Density: 922 kg / m ³ , MFR (190 ° C.) = 5.3 g / 10 min, melting point = 113 ° C.
<Thermoplastic elastomer-based resin (a3)>
TPE1: "Tuffmer" (registered trademark) PN-3560 manufactured by Mitsui Chemicals
Density 866 kg / m ³ , MFR (230 ° C.) = 6.0 g / 10 min, melting point = 160 ° C., crystallization temperature = 60 ° C., glass transition temperature = −25 ° C., crystal melting energy = 23 J / g
TPE2: Prime polymer “Prime TPO” (registered trademark) M142E
Density 900 kg / m ³ , MFR (230 ° C.) = 10.0 g / 10 min, melting point = 153 ° C., crystallization temperature = 80 ° C., glass transition temperature = −23 ° C., crystal melting energy = 29 J / g
TPE3: “INFUSE” (registered trademark) 9107 manufactured by Dow Chemical
Density 866 kg / m ³ , MFR (230 ° C.) = 3.0 g / 10 min, melting point = 121 ° C., crystallization temperature = 95 ° C., glass transition temperature = −62 ° C., crystal melting energy = 15 J / g
TPE4: “Tuffmer” (registered trademark) PN-2070 manufactured by Mitsui Chemicals
Density 868 kg / m ³ , MFR (230 ° C.) = 7.0 g / 10 min, melting point = 140 ° C., crystallization temperature = 62 ° C., glass transition temperature = −23 ° C., crystal melting energy = 23 J / g
Foaming agent: “Binihol AC # R” (registered trademark) manufactured by Azodicarbonamide Eiwa Chemical Industries
Crosslinking aid: 55% divinylbenzene antioxidant manufactured by Wako Pure Chemical Industries: “IRGANOX” (registered trademark) 1010 manufactured by BASF Corporation.

[Examples 1 to 20], [Comparative Examples 1 to 10]
The foams prepared in Examples 1 to 20 and Comparative Examples 1 to 10 are as follows.
Mixing the polypropylene resin (a1), the polyethylene resin (a2), the thermoplastic elastomer resin (a3), the foaming agent, the crosslinking aid and the antioxidant shown in Table 1 in respective ratios using a Henschel mixer, Using a twin screw extruder, melt extrusion was performed at a temperature of 170 ° C., and a polyolefin resin sheet having a predetermined thickness was produced using a T die. The polyolefin resin sheet thus obtained was irradiated with an electron beam having an acceleration voltage of 800 kV and a predetermined absorbed dose from one side to obtain a crosslinked sheet, and then the crosslinked sheet was placed on a salt bath at a temperature of 220 ° C. Floating and heated from above with an infrared heater to cause foaming. The foam is cooled with water at a temperature of 60 ° C., the foam surface is washed with water and dried, the thickness is 1.5 to 3.0 mm, the apparent density is 50 to 100 kg / m ³ , and the gel fraction is 35. A long roll of ˜45% polyolefin resin foam (A) was obtained.

The skin material (B) was produced as follows.
The skin material (B) is a thermoplastic polyolefin elastomer having endothermic peaks at 95 ° C. and 138 ° C. with a differential scanning calorimeter, melt kneaded with an extruder, and has a thickness shown in Table 1 from the T-type die. A sheet was obtained.

About the laminated body, it produced as follows.
In the polyolefin resin foam (A), the surface heated on the side of the radiation heater at the time of foaming is heated to 146 ° C., and the gap between the rolls is changed to the thickness of the skin material (B) and the thickness of the polyolefin resin foam (A). While being nipped at -1.0 mm from the sum of the above, the heated surface side and the skin material (B) were heat-sealed to obtain a laminate. Table 1 shows each physical property and evaluation status of the polyolefin resin foam (A), the skin material (B), and the laminate.

The present invention is suitable for automobile interior materials such as instrument panels and door panels.

Claims (4)

A polyolefin resin foam (A) and a skin material (B) laminate, wherein the polyolefin resin foam (A) is 100% by mass of the polyolefin resin constituting the polyolefin resin foam (A). 30 to 60% by mass of polypropylene resin (a1), 1 to 20% by mass of polyethylene resin (a2), and 30% by mass or more of thermoplastic elastomer resin (a3) A laminate characterized by the above. The laminate according to claim 1, wherein a tensile elongation of the laminate comprising the skin material (B) and the polyolefin resin foam (A) is 30% or more in a temperature environment of -35 ° C. It is a laminate of polyolefin resin foam (A) and skin material (B),
The polyolefin resin foam (A) has an endothermic peak by a differential scanning calorimeter (DSC) of 100 ° C. or higher and 130 ° C. or lower and 145 ° C. or higher,
The skin material (B) has an endothermic peak by a differential scanning calorimeter (DSC) of at least one differential scanning calorimeter (DSC) in each region of 95 ° C to 110 ° C and 130 ° C to 160 ° C. The laminate according to claim 1, wherein the laminate has the following. The laminate according to any one of claims 1 to 3, wherein the laminate is used for automobile interior materials.