JP2008013780A - Injection foaming method using thermoplastic elastomer composition for core back type injection foaming - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an injection foaming method by which an expansion molded product having uniform shape of foam, uniform cell diameter, high closed cell property, small compression set and good appearance is obtained. <P>SOLUTION: A thermoplastic elastomer composition comprises a thermoplastic elastomer which includes an ethylene-α-olefin copolymer and a crystalline polyethylene resin, wherein the crystalline polyethylene resin constitutes a three-dimensional network structure in a matrix formed by the ethylene-α-olefin copolymer, a blowing agent and a nucleating agent, wherein the thermoplastic elastomer has a melt flow rate of ≥5 g/10 min at a temperature of 230°C and a load of 10 kg, and a melt tension of ≥3.0 gf at a temperature of 210°C and a taking-off rate of 2 m/min. The injection foaming method comprises injecting the composition into a cavity space of a mold and then enlarging the cavity space to expand the composition by opening the mold at a mold opening rate of 0.05 to 0.4 mm/sec. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a thermoplastic elastomer composition for core back type injection foam molding and an injection foam molding method using the same. More specifically, it has a three-dimensional network structure that does not depend on chemical cross-linking, has excellent workability, has high foamability, uniform cell shape and cell diameter, and has sufficient elastic recovery and flexibility. The present invention also relates to a thermoplastic elastomer composition that can be made into a foam-molded article having an excellent appearance and an injection foam-molding method using the same. Foam molded products obtained by this method include automotive interior parts such as instrument panels and glove boxes, automotive exterior parts such as weather strips, weak electrical parts, anti-vibration materials for electrical appliances, other industrial parts, building materials, and sporting goods. Etc. can be used.

  In recent years, foam molded products have been used in many product fields as cushioning materials and soft tactile components for vibration and noise of automobile interior parts, exterior parts, home appliances, information equipment, and the like. In particular, thermoplastic elastomer compositions have attracted attention as raw materials that are easy to mold and foam easily. Examples of such a thermoplastic elastomer composition include a thermoplastic elastomer composition that can be dynamically cross-linked, and a foamed molded article is obtained using the thermoplastic elastomer composition disclosed in JP-A-6-73222. It is known that

  However, the crosslinked rubber component contained in such a dynamically crosslinkable thermoplastic elastomer composition cannot be foamed uniformly, and only the crystalline polyolefin foams uniformly, resulting in an inhomogeneous foam molded product as a whole. Become. Further, since the foaming gas escapes from the surface of the molded product, the surface is not smooth and the appearance is inferior. Furthermore, in the foamed molded article using this thermoplastic elastomer composition, odor and discoloration are not sufficiently reduced. In addition, there are many problems to be solved, such as complicated manufacturing processes, expensive cross-linking agents that can be used, and limited applications due to contamination with cross-linking agents. Moreover, in the non-crosslinked type, since the foamed molded product to be produced does not have a crosslinked structure, there is a problem that permanent set due to compression is large.

  As a thermoplastic elastomer composition, for example, a foam molded product obtained by using a thermoplastic elastomer composition described in Patent Document 1 below is more flexible than the conventional one. On the other hand, a non-crosslinked olefinic thermoplastic elastomer composition can also be foamed, and the composition can be easily and uniformly foamed by melting.

JP-A-6-73222

  However, the above-mentioned injection foam molding method has a problem that a foam molded product having appropriate flexibility and excellent cushioning properties cannot be obtained because the cell diameter of the foam molded product is increased. Furthermore, the cell diameter is non-uniform, and in particular, there is a tendency to be a foam molded product in which the cell diameter differs greatly between the vicinity of the gate and the end portion.

  The present invention solves the above-described problems, and has excellent physical properties such as uniform cell shape and cell diameter, high closed cell properties, low compression set, and good appearance. It is an object of the present invention to provide a core-back type thermoplastic elastomer composition for injection foam molding and an injection foam molding method using the same.

The present invention achieves the above object, and is exemplified below.
1. An ethylene / α-olefin copolymer (1) and a crystalline polyethylene resin (2), wherein the crystalline polyethylene is contained in a matrix comprising the ethylene / α-olefin copolymer (1). Resin (2) contains a thermoplastic elastomer constituting a three-dimensional network structure, a foaming agent (4) and a nucleating agent (5),
The thermoplastic elastomer has a melt flow rate of 5 g / 10 min or more at a temperature of 230 ° C. and a load of 10 kg, and a melt tension of 210 g at a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back mold injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back mold injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.
2. The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the foaming agent (4) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate, 2. The core-back injection foam molding according to 1, wherein the composition contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. Thermoplastic elastomer composition.
3. In a matrix comprising an ethylene / α-olefin copolymer (1) and a crystalline polyethylene resin (2) and comprising the ethylene / α-olefin copolymer (1), the crystallinity A thermoplastic elastomer in which the polyethylene resin (2) constitutes a three-dimensional network structure;
A foaming agent-containing resin in which the foaming agent (4) is kneaded into the olefin resin (6);
A nucleating agent (5) is blended with a nucleating agent-containing resin kneaded into the olefin resin (6),
The melt flow rate at a temperature of 230 ° C. and a load of 10 kg of the thermoplastic elastomer is 5 g / 10 min or more, and the melt tension at 210 ° C. and a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back mold injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back mold injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.
4). The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the foaming agent (4) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate, 4. The core-back injection foam molding according to 3 above, wherein the composition contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. Thermoplastic elastomer composition.
5. An ethylene / α-olefin copolymer (1), a crystalline polyethylene resin (2), and the following block copolymer (3), the ethylene / α-olefin copolymer (1) A thermoplastic elastomer in which the crystalline polyethylene resin (2) and the block copolymer (3) constitute a three-dimensional network structure, a foaming agent (4), and a nucleating agent (5). Containing
The thermoplastic elastomer has a melt flow rate of 5 g / 10 min or more at a temperature of 230 ° C. and a load of 10 kg, and a melt tension of 210 g at a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back mold injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back mold injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.
[Block copolymer (3)]; a block having higher compatibility with the crystalline ethylene polymer block and the ethylene / α-olefin copolymer (1) than with the crystalline polyethylene resin (2). A block copolymer comprising: The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the foaming agent (4) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate, 6. The core-back injection foam molding according to 5 above, wherein the composition contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. Thermoplastic elastomer composition.
7). An ethylene / α-olefin copolymer (1), a crystalline polyethylene resin (2), and the following block copolymer (3) are contained, and the ethylene / α-olefin copolymer (1 A thermoplastic elastomer in which the crystalline polyethylene resin (2) and the block copolymer (3) constitute a three-dimensional network structure in a matrix comprising
A foaming agent-containing resin in which the foaming agent (4) is kneaded into the olefin resin (6);
A nucleating agent (5) is blended with a nucleating agent-containing resin kneaded into the olefin resin (6),
The melt flow rate at a temperature of 230 ° C. and a load of 10 kg of the thermoplastic elastomer is 5 g / 10 min or more, and the melt tension at 210 ° C. and a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back mold injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back mold injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.
[Block copolymer (3)]; a block having higher compatibility with the crystalline ethylene polymer block and the ethylene / α-olefin copolymer (1) than with the crystalline polyethylene resin (2). A block copolymer comprising: The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the foaming agent (4) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate, 8. The core-back injection foam molding according to 7 above, wherein the composition contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. Thermoplastic elastomer composition.
9. An ethylene / α-olefin copolymer (1) and a crystalline polyethylene resin (2), wherein the crystalline polyethylene is contained in a matrix comprising the ethylene / α-olefin copolymer (1). The thermoplastic resin (2) comprising a three-dimensional network structure, an organic foaming agent (4a), an inorganic foaming agent (4b) and a nucleating agent (5),
The melt flow rate at a temperature of 230 ° C. and a load of 10 kg of the thermoplastic elastomer is 5 g / 10 min or more, and the melt tension at 210 ° C. and a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back mold injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back mold injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.
10. The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the organic foaming agent (4a) is an azo foaming agent, a nitroso foaming agent, a sulfonyl hydrazide foaming agent, or a triazine foaming agent. And the tetrazole-based blowing agent, and the inorganic foaming agent (4b) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate. 10. The core-back injection foam molding thermoplastic elastomer according to 9 above, which further contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. Composition.
11. In a matrix comprising an ethylene / α-olefin copolymer (1) and a crystalline polyethylene resin (2) and comprising the ethylene / α-olefin copolymer (1), the crystallinity A thermoplastic elastomer in which the polyethylene resin (2) constitutes a three-dimensional network structure;
(I) An organic foaming agent-containing resin in which the organic foaming agent (4a) is kneaded into the olefin resin (6) and an inorganic foaming agent in which the inorganic foaming agent (4b) is kneaded into the olefin resin (6) A foaming agent-containing resin, or (ii) an organic / inorganic foaming agent-containing resin in which the organic foaming agent (4a) and the inorganic foaming agent (4b) are kneaded into the olefin resin (6);
A nucleating agent (5) is blended with a nucleating agent-containing resin kneaded into the olefin resin (6),
The melt flow rate at a temperature of 230 ° C. and a load of 10 kg of the thermoplastic elastomer is 5 g / 10 min or more, and the melt tension at 210 ° C. and a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back mold injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back mold injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.
12 The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the organic foaming agent (4a) is an azo foaming agent, a nitroso foaming agent, a sulfonyl hydrazide foaming agent, or a triazine foaming agent. And the tetrazole-based blowing agent, and the inorganic foaming agent (4b) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate. 12. The core-back type injection foam molding thermoplastic elastomer according to 11 above, which further contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. Composition.
13. An ethylene / α-olefin copolymer (1), a crystalline polyethylene resin (2), and the following block copolymer (3), the ethylene / α-olefin copolymer (1) A thermoplastic elastomer, an organic foaming agent (4a), an inorganic foam (wherein the crystalline polyethylene resin (2) and the block copolymer (3) constitute a three-dimensional network structure). 4b) and a nucleating agent (5),
The melt flow rate at a temperature of 230 ° C. and a load of 10 kg of the thermoplastic elastomer is 5 g / 10 min or more, and the melt tension at 210 ° C. and a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back mold injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back mold injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.
[Block copolymer (3)]; a block having higher compatibility with the crystalline ethylene polymer block and the ethylene / α-olefin copolymer (1) than with the crystalline polyethylene resin (2). A block copolymer comprising: The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the organic foaming agent (4a) is an azo foaming agent, a nitroso foaming agent, a sulfonyl hydrazide foaming agent, or a triazine foaming agent. And the tetrazole-based blowing agent, and the inorganic foaming agent (4b) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate. 14. The thermoplastic elastomer for core back type injection foam molding as described in 13 above, which further contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. Composition.
15. An ethylene / α-olefin copolymer (1), a crystalline polyethylene resin (2), and the following block copolymer (3) are contained, and the ethylene / α-olefin copolymer (1 A thermoplastic elastomer in which the crystalline polyethylene resin (2) and the block copolymer (3) constitute a three-dimensional network structure,
(I) An organic foaming agent-containing resin in which the organic foaming agent (4a) is kneaded into the olefin resin (6) and an inorganic foaming agent in which the inorganic foaming agent (4b) is kneaded into the olefin resin (6) A foaming agent-containing resin, or (ii) an organic / inorganic foaming agent-containing resin in which the organic foaming agent (4a) and the inorganic foam (4b) are kneaded into the olefin resin (6);
A nucleating agent (5) is blended with a nucleating agent-containing resin kneaded into the olefin resin (6),
The melt flow rate at a temperature of 230 ° C. and a load of 10 kg of the thermoplastic elastomer is 5 g / 10 min or more, and the melt tension at 210 ° C. and a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back type injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back type injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.
[Block copolymer (3)]; a block having higher compatibility with the crystalline ethylene polymer block and the ethylene / α-olefin copolymer (1) than with the crystalline polyethylene resin (2). A block copolymer comprising: The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the organic foaming agent (4a) is an azo foaming agent, a nitroso foaming agent, a sulfonyl hydrazide foaming agent, or a triazine foaming agent. And the tetrazole-based blowing agent, and the inorganic foaming agent (4b) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate, and the present composition 15. The thermoplastic elastomer for core-back type injection foam molding as described in 15 above, which contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. Composition.
17. The core-back type injection-foaming thermoplastic elastomer composition according to any one of 1 to 16 above is injected into a cavity space in a mold, and thereafter a mold opening speed of 0.05 to 0.4 mm / sec. An injection foam molding method comprising: expanding a cavity space by opening a mold to foam the thermoplastic elastomer composition to obtain a foam molded article having a skin layer and a foam layer.
18. 18. The injection foam molding method as described in 17 above, wherein the mold retraction delay time is 0 to 5 seconds after completion of filling.
19. 18. The injection foam molding according to 17 above, wherein the mold is opened so that a final thickness of the foam molded product is 1.1 to 5.0 times an initial thickness of a material filled in the cavity space in the mold. Method.
20. 18. The injection foam molding method as described in 17 above, wherein a foam molded product is formed on the surface of the substrate.

According to the thermoplastic elastomer composition for core back type foam injection molding of the present invention, it has a three-dimensional network structure that does not depend on chemical crosslinking, and this three-dimensional network structure melts and disappears when the melting point is exceeded. A thermoplastic elastomer composition having excellent processability can be obtained. If this thermoplastic elastomer composition is used, it is possible to obtain a foam-molded product that has high foamability, a uniform cell shape, a small cell diameter, and excellent elastic recovery, flexibility and appearance. .
In addition, when an organic foaming agent and an inorganic foaming agent are used in combination, the decomposition product produced by the decomposition of the inorganic foaming agent that decomposes in advance functions as a nucleating agent. There is no need to blend. Furthermore, the combined use can also reduce the content of the organic foaming agent in which the odor remaining in the foamed molded product becomes a problem. In particular, when an inorganic foaming agent and a weakly acidic compound are used in combination, the decomposition rate is increased. In addition, if the particle size of the nucleating agent is 2 to 50 μm, a foam molded product having an appropriate cell diameter and excellent cushioning properties can be obtained.
According to the injection foam molding method of the present invention, there is a three-dimensional network structure that does not depend on chemical crosslinking, and this three-dimensional network structure melts and disappears when the melting point is exceeded. By using a thermoplastic elastomer composition for injection and injection foam molding by a core back method at a specific mold opening speed, high foamability, uniform cell shape, small cell diameter, and elastic recovery In addition, a foam molded article having excellent flexibility and appearance can be obtained.
Further, by specifying the mold retraction delay time and the final thickness of the foam molded product relative to the initial thickness of the material filled in the cavity space in the mold, it is possible to obtain a foam molded product of better quality. . In particular, when a weakly acidic compound is used in combination, the decomposition rate is increased. Further, if a foam molded product is formed on the surface of a substrate made of resin or the like, an interior part such as an automobile made of a laminate of the substrate and the foamed layer can be easily molded.

  The “ethylene / α-olefin copolymer (1)” [hereinafter referred to as “EAO copolymer (1)”. ] Is a copolymer obtained by using ethylene and an α-olefin excluding ethylene as main monomers. When the total of ethylene units and α-olefin units contained in the EAO copolymer (1) is 100 mol%, the ethylene unit content is preferably 40 to 90 mol%, particularly preferably 50 -90 mol%. When the ethylene unit content is less than 40 mol%, the mechanical strength of the foamed molded product may be lowered. On the other hand, if it exceeds 90 mol%, it may become too hard.

  Examples of the EAO copolymer (1) include an ethylene / propylene copolymer, an ethylene / propylene / non-conjugated diene copolymer, an ethylene / butene-1 copolymer, and an ethylene / butene-1 / non-conjugated diene copolymer. A copolymer having an olefin unit as a main component such as a polymer, an ethylene / octene-1 copolymer, and an ethylene / octene-1 / non-conjugated diene copolymer can be used. These copolymers may use only 1 type and may use 2 or more types together. Further, as the non-conjugated diene, ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene and the like are preferable. These non-conjugated dienes are preferably used in such a quantitative ratio that the iodine value of the EAO copolymer (1) is 40 or less.

The Mooney viscosity of the EAO copolymer (1) is not particularly limited, but is preferably 10 to 500 ML _{1 + 4} (100 ° C.), particularly preferably 30 to 400 ML _{1 + 4} (100 ° C.). When the Mooney viscosity is less than 10 ML _{1 + 4} (100 ° C.), the mechanical strength and elastic recovery of the foam-molded product tend to decrease. On the other hand, if it exceeds 500 ML _{1 + 4} (100 ° C.), the crystalline polyethylene resin (2) may not be sufficiently dispersed, which is not preferable.

  The “crystalline polyethylene resin (2)” is composed mainly of ethylene, and the ethylene unit content is 90 to 100 mol%. In addition, when this crystalline polyethylene resin (2) is dissolved in boiling n-hexane, the insoluble content is preferably 10% by mass or more, particularly preferably 20% by mass or more (usually 95% by mass or less). . If the insoluble content is less than 10% by mass, the processability of the resulting thermoplastic elastomer composition and the mechanical strength of the foamed molded product may be lowered. In addition, it is preferable that the melting peak by a differential scanning calorimeter of crystalline polyethylene-type resin (2) is 100 degreeC or more.

  As this crystalline polyethylene resin (2), in addition to polyethylene, ethylene and propylene, butene-1, 4-methyl-pentene-1, hexene-1, octene-1, etc., C3-8 α- Examples thereof include a copolymer obtained by copolymerizing an olefin and having an ethylene unit content of 90 mol% or more. In addition, as polyethylene, any of low density polyethylene manufactured by the high pressure method, high density polyethylene manufactured by the medium low pressure method, and linear low density polyethylene can be used, and two types manufactured by different methods. The above can also be used together.

  The content of each of the EAO copolymer (1) and the crystalline polyethylene resin (2) is preferably 10 to 10% when the total content is 100% by mass. It is 94 mass%, More preferably, it is 20-94 mass%, Most preferably, it is 40-94 mass%. The crystalline polyethylene resin (2) is preferably 5 to 80% by mass, more preferably 5 to 50% by mass, and particularly preferably 5 to 30% by mass. When the content of the EAO-based copolymer (1) is less than 10% by mass, the elastic recovery of the foamed molded product may be lowered. When the content exceeds 94% by mass, the resulting thermoplastic elastomer composition is processed. It is not preferable because the property tends to decrease. Further, if the content of the crystalline polyethylene resin (2) is less than 5% by mass, the elastic recovery property may be lowered, and if it exceeds 80% by mass, the elasticity tends to be lowered.

  The “block copolymer (3)” has a block highly compatible with the EAO copolymer (1) and a block highly compatible with the crystalline polyethylene resin (2). Therefore, the EAO copolymer (1) and the crystalline polyethylene resin (2) have a structure as if they were bridged with the block copolymer (3) in between, and the EAO copolymer (1) Is considered to be a matrix in which the crystalline polyethylene resin (2) and the block copolymer (3) form a three-dimensional network structure.

  Examples of the crystalline ethylene polymer block that the block copolymer (3) has include a block made of an ethylene homopolymer or a copolymer having an ethylene unit content of 50 mol% or more. The block copolymer (3) preferably includes a crystalline ethylene polymer block at both ends. With such a block copolymer (3), a uniform three-dimensional network structure is formed. In general, the crystalline polyethylene resin (2) and the block copolymer (3) each form a three-dimensional network structure.

  As the block copolymer (3), both terminal blocks are composed of butadiene polymer blocks, the intermediate block is composed of at least one of a conjugated diene polymer block and a vinyl aromatic compound-conjugated diene random copolymer block. A block copolymer obtained by hydrogenating a block copolymer in which the 1,2-vinyl group content of the block is less than the 1,2-vinyl group content of the intermediate block is preferred.

  Furthermore, in the block copolymer before hydrogenation, when the total of both terminal blocks and the intermediate block is 100% by mass, both terminal blocks are 5 to 90% by mass, particularly 10 to 80% by mass, More preferably, the 1,2-vinyl group content is less than 25 mol%, and the 1,2-vinyl group content of the intermediate block is 25 mol% or more. If the content of both terminal blocks is less than 5% by mass, the difference in crystallinity from the EAO copolymer (1) serving as a matrix becomes large, and it becomes difficult to form a three-dimensional network structure. On the other hand, when the content exceeds 90% by mass, the hardness of the foam-molded product may undesirably increase.

  Both terminal blocks are preferably 1,3-butadiene polymer blocks comprising 90% by mass or more, particularly 95% by mass or more of 1,3-butadiene units. The 1,2-vinyl group content is preferably less than 25 mol%, more preferably 20 mol% or less, particularly preferably 15 mol% or less. When the 1,2-vinyl group content of both terminal blocks is 25 mol% or more, the melting point of the crystal after the hydrogenation is remarkably lowered, and the mechanical strength of the foam-molded product tends to be lowered. The number average molecular weight of both terminal blocks is preferably 25,000 to 630,000, particularly preferably 100,000 to 480,000. In the block copolymer (3), both hydrogenated terminal blocks have a polymethylene structure.

  The intermediate block is preferably a conjugated diene polymer block comprising 50% by mass or more, particularly 60% by mass or more of conjugated diene units. Conjugated dienes include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 1,3-pentadiene, 2-methyl-1,3-pentadiene, 1,3-hexadiene, 4,5 -Diethyl-1,3-octadiene, 3-butyl-1,3-octadiene, chloroprene and the like. Among these, 1,3-butadiene, isoprene, 1,3-pentadiene and the like are preferable, and 1,3-butadiene is particularly preferable. Only 1 type may be used for a conjugated diene and it may use 2 or more types together.

  The 1,2-vinyl group content of the intermediate block is preferably 25 mol% or more, more preferably 25 to 90 mol%, particularly preferably 25 to 85 mol%. When this content is less than 25 mol%, the flexibility of the foam-molded product tends to decrease. The number average molecular weight of this intermediate block is preferably 5,000 to 665,000, particularly preferably 20,000 to 540,000.

  When the intermediate block has a vinyl aromatic unit, the content of this monomer unit is preferably 35% by mass or less, more preferably 30% by mass or less, particularly preferably when the entire intermediate block is 100% by mass. Is 25% by mass or less. The vinyl aromatic unit tends to increase the glass transition temperature of the block copolymer (3), and lower the low temperature characteristics of the resulting thermoplastic elastomer composition and the flexibility of the foam molded product. This intermediate block has a structure similar to that of a rubbery ethylene / butene-1 copolymer or a vinyl aromatic compound / ethylene / butene-1 copolymer by hydrogenation.

  In the block copolymer (3), it is preferable that at least 80%, particularly 90%, more preferably 95 to 100% of the double bond of the block copolymer before hydrogenation is saturated by hydrogenation. When there are many double bonds remaining in the block copolymer (3), the thermal stability and durability of the foam molded product tend to be lowered. Furthermore, the number average molecular weight of the block copolymer (3) is preferably 50,000 to 700,000, particularly preferably 100,000 to 600,000. If the number average molecular weight is less than 50,000, the heat resistance and mechanical strength of the foamed molded product may be lowered. If it exceeds 700,000, the fluidity and workability of the resulting thermoplastic elastomer composition. May decrease. The block copolymer (3) that can be used in the present invention can be prepared by the method disclosed in JP-A-3-1289576.

The block copolymer (3) may be one in which a plurality of block copolymers (3) are linked by a coupling agent residue. For example, when both terminal blocks are “A” and the intermediate block is “B”, [ABAX] _n- (ABA) (where n is an integer of 2 to 4, X may be a coupling agent residue). If the molecular weight of the coupling agent residue is sufficiently small compared to the molecular weight of each block and does not affect the crystallinity of the block copolymer (3), [ABX] _n − (BA) (where n is an integer of 2 to 4, and X is a coupling agent residue). That is, when a relatively small coupling agent residue is omitted, [AB] _n -A may be used.

  As coupling agents, diethyl adipate, divinylbenzene, tetrachlorosilicon, butyltrichlorosilicon, tetrachlorotin, butyltrichlorotin, dimethylchlorosilicon, tetrachlorogermanium, 1,2-dibromoethane, 1,4-chloromethyl Benzene, bis (trichlorosilyl) ethane, epoxidized linseed oil, tolylene diisocyanate, 1,2,4-benzene triisocyanate and the like can be used.

  The block copolymer (3) may be a modified hydrogenated block polymer modified with a functional group. Examples of the functional group include a carboxyl group, an acid anhydride group, a hydroxyl group, an epoxy group, a halogen atom, an amino group, an isocyanate group, a sulfonyl group, and a sulfonate group. Denaturation can be performed by a known method. The content of the functional group in the modified block polymer is preferably 0.01 to 10 mol%, more preferably 0.1 to 8 mol%, when the total monomer units of the polymer are 100 mol%. Particularly preferred is 0.15 to 5 mol%.

  Preferred monomers for introducing these functional groups include acrylic acid, methacrylic acid, itaconic acid, maleic acid, maleic anhydride, glycidyl acrylate, glycidyl methacrylate, allyl glycidyl ether, hydroxyethyl methacrylate, hydroxypropyl Examples include methacrylate, hydroxyethyl acrylate, hydroxypropyl acrylate, and dimethylaminoethyl methacrylate.

  The content of each of the EAO copolymer (1), the crystalline polyethylene resin (2) and the block copolymer (3) is EAO copolymer ( 1) is preferably 10 to 94% by mass, more preferably 20 to 94% by mass, still more preferably 25 to 94% by mass, particularly preferably 40 to 94% by mass, and most preferably 50 to 94% by mass. is there. The crystalline polyethylene resin (2) is preferably 5 to 80% by mass, more preferably 5 to 50% by mass, particularly preferably 5 to 30% by mass, and the block copolymer (3) is preferably Is 1 to 80% by mass, more preferably 2 to 50% by mass, and particularly preferably 3 to 30% by mass.

  When the content of the EAO-based copolymer (1) is less than 10% by mass, the elastic recovery of the foamed molded product may be deteriorated, and when it exceeds 94% by mass, the resulting thermoplastic elastomer composition is processed. It is not preferable because the property tends to decrease. Further, if the content of the crystalline polyethylene resin (2) is less than 5% by mass, the elastic recovery property may be lowered, and if it exceeds 80% by mass, the elasticity tends to be lowered. Furthermore, if the content of the block copolymer (3) is less than 1% by mass, the elastic recovery of the foamed molded product may be lowered. If the content exceeds 80% by mass, the resulting thermoplastic elastomer composition Workability tends to decrease, which is not preferable.

  Further, when the total of these three components is 100% by mass, the EAO copolymer (1) is 40 to 94% by mass, particularly 50 to 94% by mass, and the crystalline polyethylene resin (2) and The total of the block copolymer (3) is 6 to 60% by mass, particularly 6 to 50% by mass, and the total of the crystalline polyethylene resin (2) and the block copolymer (3) is 100% by mass. When the crystalline polyethylene resin (2) is 20 to 80% by mass, particularly 30 to 70% by mass, a three-dimensional network structure is formed in a particularly stable manner.

  In the block copolymer (3), the crystalline ethylene copolymer block (A) at both ends functions as a block highly compatible with the crystalline polyethylene resin (2), and an intermediate conjugated diene polymer is used. The resulting block (B) functions as a block more compatible with the EAO copolymer (1).

  The thermoplastic elastomer according to the present invention contains the ethylene / α-olefin copolymer (1) and the crystalline polyethylene resin (2). You may contain another additive as needed.

  The thermoplastic elastomer according to the present invention has a melt flow rate measured at a temperature of 230 ° C. and a load of 10 kg of 5 g / 10 min or more, preferably 10 g / 10 min or more, particularly preferably 15 g / 10 min or more (usually) 200 g / 10 min or less). When the melt flow rate is less than 5 g / 10 minutes, the fluidity at the time of injecting the resulting thermoplastic elastomer composition becomes insufficient, and in particular, in a product having a long flow distance, poor filling occurs. Further, this thermoplastic elastomer has a melt tension of 3.0 gf or more, preferably 3.5 gf or more, particularly preferably 4.0 gf or more (usually 12.0 gf or more) at 210 ° C. and a take-off speed of 2 m / min. The following). When the melt tension is less than 3.0 gf, the cell membrane is broken when foaming is performed by the core back, and the cells are connected, and a large void is generated inside the foamed molded product, resulting in a product with poor cushioning properties.

  The thermoplastic elastomer preferably has a JIS-A hardness of a solid molded product of 50 to 90, particularly preferably 55 to 80. If the hardness is less than 50, the surface of the foam-molded product becomes excessively soft and easily damaged. On the other hand, when it exceeds 90, there exists a tendency for a softness | flexibility and elastic recovery property to fall.

  As the “foaming agent (4)”, an organic foaming agent (4a) such as a thermal decomposition foaming agent, a volatile foaming agent and a hollow particle foaming agent, and an inorganic foaming agent (4b) may be used. it can. These foaming agents are preferably selected and used according to the production method of the foam molded article. Only one type of foaming agent may be used, or two or more types may be used in combination as long as a foamed molded article having a predetermined appearance and physical properties is obtained.

  Examples of the pyrolytic organic foaming agent (4a) include nitroso foaming agents such as N, N′-dinitrosopentamethylenetetramine and N, N′-dimethyl-N, N′-dinitrosotephthalamide; azodicarbon Amide, azodicarboxylic acid barium, barium azodicarboxylate azo foaming agent; p, p-oxybisbenzenesulfonyl hydrazide, 4,4'-oxybis (benzenesulfonyl hydrazide), sulfonyl hydrazide such as p-toluenesulfonyl semicarbazide Foaming agents; triazine foaming agents such as trihydrazinotriazine; tetrazole foaming agents such as 5-phenyltetrazole, azobistetrazole diguanidine, azobistetrazoleaminoguanidine, and the like.

  Volatile organic foaming agents (4a) include aliphatic hydrocarbons such as propane, butane and pentane; alicyclic hydrocarbons such as cyclobutane, cyclopentane and cyclohexane; chlorodifluoromethane, difluoromethane, trifluoromethane , Trichlorofluoromethane, dichloromethane, dichlorofluoromethane, dichlorodifluoromethane, trichlorofluoromethane, chloromethane, chloroethane, dichlorotrifluoroethane, dichlorofluoroethane, chlorodifluoroethane, dichloropentafluoroethane, pentafluoroethane, trifluoroethane, dichloro Halogenation of tetrafluoroethane, trichlorotrifluoroethane, tetrachlorodifluoroethane, chloropentafluoroethane, perfluorocyclobutane, etc. Hydrogen like; carbon dioxide, nitrogen, air, etc., and the like, and water and the like.

  The hollow particle type organic foaming agent (4a) is a thermally expandable microsphere having an outer shell made of a thermoplastic resin and an encapsulating expansion agent. As the swelling agent, the same volatile foaming agent is used. When the foaming agent (4a) is 100% by mass, the expansion agent is preferably 5 to 30% by mass. As the thermoplastic resin forming the outer shell, (meth) acrylonitrile, (meth) acrylate, vinyl halide, vinylidene halide, styrene compound, vinyl acetate, butadiene, chloroprene, vinyl pyridine, etc. are polymerized or copolymerized. Things.

  The thermoplastic resin forming the outer shell is divinylbenzene, ethylene glycol (meth) acrylate, triethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, 1,3-butylene glycol di (meta). ) Acrylate, allyl (meth) acrylate, triacryl formal, triallyl isocyanurate or the like. The mass average particle diameter of the hollow particle type foaming agent before expansion is usually 1 to 100 μm.

  The content of the organic foaming agent (4a) may be selected according to the type of foaming agent, a predetermined foaming ratio, etc., and the total amount of polymer components contained in the thermoplastic elastomer composition of the present invention is 100 parts by mass. When used, it is preferably 0.1 to 10 parts by mass, particularly preferably 0.5 to 5 parts by mass.

  Examples of the inorganic foaming agent (4b) include inorganic compounds such as sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate, which are pyrolytic foaming agents. The content of the inorganic foaming agent (4b) may be selected depending on the type of foaming agent, a predetermined foaming ratio, etc., and the total amount of the polymer components contained in the thermoplastic elastomer composition of the present invention is 100 parts by mass. When used, it is preferably 0.1 to 10 parts by mass, particularly preferably 0.5 to 5 parts by mass.

  When the organic foaming agent (4a) and the inorganic foaming agent (4b) are used in combination, the content ratio (4a) / (4b) is preferably 5 to 50/95 to 5 when the total is 100% by mass. Especially preferably, it is 5-20 / 95-80.

  When using the said inorganic type foaming agent (4b), it is preferable to make a composition contain a weak acidic compound further. By including a weakly acidic compound, the decomposition rate can be increased. Examples of weakly acidic compounds include organic acids such as oxalic acid, malonic acid, citric acid and lactic acid, inorganic acids such as boric acid, and acidic salts such as monosodium citrate and acidic potassium tartrate, especially citric acid and citric acid. Mono soda is preferred. These may use only 1 type and can also use 2 or more types together.

The amount of the weakly acidic compound is preferably 10 to 60 parts by mass, particularly preferably 25 to 50 parts by mass, when the inorganic foaming agent (4b) is 100 parts by mass.
If the organic foaming agent (4a) is used, a high-magnification foam molded product can be easily obtained, but odor may remain in the foam molded product. On the other hand, when the inorganic foaming agent (4b) is used, almost no odor is generated, which is particularly preferable in applications where the odor of a vehicle interior material or the like becomes a problem. In addition, when the inorganic foaming agent (4b) is used in combination, the content of the organic foaming agent (4a) can be reduced, which can reduce odor, which is preferable.

  As the “nucleating agent (5)”, powders of inorganic compounds such as calcium carbonate, talc, mica, silica, titania and the like can be used. By containing these nucleating agents, the cell diameter can be easily adjusted, and a foamed molded article having appropriate flexibility and the like can be obtained. The particle size of the nucleating agent is not particularly limited, but is preferably 2 to 50 μm, particularly preferably 5 to 20 μm. When the particle size is less than 2 μm, it is difficult to obtain an effect as a nucleating agent, and the cell diameter is increased, which is not preferable. On the other hand, if the particle size exceeds 50 μm, the number of cells becomes coarse and the number becomes small, the foamed molded product becomes too flexible, and the cushioning property is inferior. The content of the nucleating agent is preferably from 0.01 to 3 parts by mass, more preferably from 0.05 to 3 parts, when the total amount of the polymer components contained in the thermoplastic elastomer composition of the present invention is 100 parts by mass. 2 parts by mass, particularly preferably 0.1 to 1 part by mass.

  As the nucleating agent (5), a decomposition product generated by decomposition of the inorganic foaming agent (4b) can also be used. When the organic foaming agent (4a) and the inorganic foaming agent (4b) are used in combination, the inorganic foaming agent (4b) decomposes first. For example, when sodium hydrogen carbonate is used, carbonic acid is decomposed after decomposition. Sodium and the like are produced. And when an organic type foaming agent (4a) decomposes | disassembles, this decomposition product functions as a nucleating agent. Therefore, even if a nucleating agent is not blended, a foamed molded article having an appropriate cell diameter, flexible and excellent in cushioning properties can be obtained.

  The thermoplastic elastomer composition of the present invention can further contain other polymers. For example, as the resin component, a crystalline α-olefin polymer having 3 or more carbon atoms can be contained. Thereby, the surface of the foam molded product can be made smoother. Examples of the crystalline α-olefin polymer include polypropylene, polybutene-1, poly-4-methyl-pentene-1, polyhexene-1, propylene / ethylene copolymer, propylene / butene-1 copolymer, and the like. . These may use only 1 type and can also use 2 or more types together.

  The content of the crystalline α-olefin polymer is the total amount of the polymer, EAO copolymer (1), crystalline polyethylene resin (2), and block copolymer (3) being 100. In the case of mass parts, it is preferably 10 parts by mass or less, more preferably 5 parts by mass or less, and particularly preferably 4 parts by mass or less. If this content exceeds 10 parts by mass, a stable three-dimensional network structure may not be formed.

  Further, the thermoplastic elastomer composition of the present invention can contain a mineral oil softener. Examples of the mineral oil softener include naphthenic and paraffinic mineral oils. By containing such a softening agent, the processability of the resulting thermoplastic elastomer composition can be improved. The blending amount of the mineral oil softener is usually 200 masses when the total of the EAO copolymer (1), the crystalline polyethylene resin (2) and the block copolymer (3) is 100 mass parts. Part or less, preferably 100 parts by weight or less, and further 50 parts by weight or less. The method and process for blending the mineral oil softener are not particularly limited.

  The thermoplastic elastomer composition for core back type injection foam molding of the present invention comprises an EAO copolymer (1), a crystalline polyethylene resin (2), and optionally a block copolymer (3) at a predetermined temperature. Supply to a closed kneading machine such as a temperature controlled Banbury mixer, pressure kneader, roll mill, single screw extruder, twin screw extruder, kneading extruder, etc., knead, preferably in the form of pellets as a thermoplastic elastomer After the preparation, the thermoplastic elastomer, the foaming agent (4) and the nucleating agent (5) can be supplied to an injection molding machine and kneaded. The kneading temperature for preparing the thermoplastic elastomer is preferably at least the temperature at which the block copolymer (3) melts, and can usually be 120 to 280 ° C. The kneading time is preferably 10 seconds to 60 minutes, particularly preferably 30 seconds to 30 minutes, although it depends on the apparatus used and the kneading temperature.

  The foaming agent (4) and the nucleating agent (5) are each previously kneaded into the olefin resin (6) to form a foaming agent-containing resin or a nucleating agent-containing resin, and then the EAO copolymer (1), It is preferable to mix with the crystalline polyethylene resin (2), and in some cases, the block copolymer (3). If it does in this way, it can disperse | distribute more uniformly in the thermoplastic-elastomer composition which can obtain a foaming agent and a nucleating agent.

  As the olefin resin (6), a resin mainly composed of ethylene units, a resin mainly composed of propylene units, an ethylene / propylene copolymer, and the like can be used. These may be crystalline or amorphous, and may be the same as the resin used as the crystalline polyethylene resin (2). Moreover, the olefin resin (6) used for the foaming agent and the olefin resin (6) used for the nucleating agent may be the same or different. The olefin resin (6) contained in the thermoplastic elastomer composition of the present invention may form a matrix depending on its crystallinity and may constitute a three-dimensional network structure. Furthermore, since the amount of the olefin resin (6) is small, the specific structure of the thermoplastic elastomer composition comprising a matrix and a three-dimensional network structure is not impaired.

  When the foaming agent-containing resin is 100% by mass, the content of the foaming agent is preferably 10 to 60% by mass, particularly preferably 20 to 50% by mass. Further, when the nucleating agent-containing resin raw material is 100% by mass, the content of the nucleating agent is preferably 2 to 20% by mass, particularly preferably 5 to 15% by mass. By preparing such high-concentration resin raw materials, so-called master batches, and blending these master batches so that the foaming agent or the nucleating agent is in a predetermined amount, in particular, the foaming agent and the nucleating agent. Even when the content of is small, they can be uniformly dispersed.

  In the thermoplastic elastomer composition of the present invention, various additives such as a lubricant, an anti-aging agent, a heat stabilizer, a light-resistant agent such as HALS, a weather-resistant agent, a metal deactivator, an ultraviolet absorber, Stabilizers such as light stabilizers, copper damage inhibitors, antibacterial agents, antifungal agents, dispersants, plasticizers, flame retardants, tackifiers, colorants such as titanium oxide, carbon black and organic pigments, ferrites, etc. Metal powder, glass fiber, inorganic fiber such as metal fiber, organic fiber such as carbon fiber and aramid fiber, composite fiber, inorganic whisker such as potassium titanate whisker, glass beads, glass balloon, glass flake, asbestos, mica, calcium carbonate , Talc, silica, calcium silicate, hydrotalcite, kaolin, diatomaceous earth, graphite, pumice, evo powder, cotton flock, cork powder, barium sulfate , Fluororesin, Polymer beads, Polyolefin wax, Cellulose powder, Rubber powder, Wood powder, etc., or mixtures thereof, Isobutylene / isoprene copolymer, Rubber such as silicone rubber, Ethylene / vinyl acetate copolymer, ABS resin A thermoplastic resin such as can be contained.

  In the injection foam molding method of the present invention, the thermoplastic elastomer composition for injection foam molding is injected into a cavity space formed in a mold of an injection molding machine and immediately or after a predetermined time has elapsed, the movable mold Alternatively, it is possible to obtain a foam molded article by a so-called core back type injection molding method in which a movable core provided in a movable mold is retreated to a predetermined position at a predetermined speed and foamed by expanding a cavity space. it can. Since the temperature of the mold is usually considerably lower than the temperature of the thermoplastic elastomer composition at the time of injection, the surface of the foam molded product formed in contact with the surface of the cavity is a dense foam that is hardly foamed. A skin layer is formed.

  The foam-molded product can also be integrally formed so as to be in contact with the surface of a substrate such as a resin. Such a laminate can be formed by arranging a base material in advance in the cavity space and injecting a thermoplastic elastomer composition on the surface thereof. Also, using an injection molding machine equipped with two injection units, first, the base material is formed by injecting the resin as the base material, and then the movable core built in the movable mold is retracted. Forming a cavity space for injecting the thermoplastic elastomer composition, then injecting the thermoplastic elastomer composition, then further retracting the movable core to expand the cavity space and foam, It can also be set as the laminated product by which the foaming molded product was laminated | stacked on the surface.

In the injection foam molding method of the present invention, the retraction speed of the movable mold or the retraction speed of the movable core provided in the movable mold, that is, the above-mentioned “mold opening speed” is 0.05 to 0.4 mm / second. It is. The mold opening speed is preferably 0.1 to 0.4 mm / second, more preferably 0.1 to 0.3 mm / second. By setting such a mold opening speed, the average cell diameter is 200 μm or less, particularly 50 to 150 μm, which is moderately fine, and the average cell diameter (D _g ) in the vicinity of the gate and the average cell diameter (D _e) ) Is small, when expressed by [(D _g / D _e ), it is 0.65 or more, particularly 0.7 or more (usually 1.2 or less). ] A homogeneous foamed molded product can be obtained.

  If the mold opening speed is less than 0.05 mm / second, cooling proceeds and foaming is insufficient, resulting in unevenness on the surface. On the other hand, when the mold opening speed exceeds 0.4 mm / second, the cell diameter becomes large and the foam molded article having excellent cushioning properties and the like cannot be obtained. In addition, the cell diameter becomes non-uniform, and in particular, the foam molded product has a greatly different cell diameter between the vicinity of the gate and the end portion.

  Furthermore, the temperature of the thermoplastic elastomer composition to be injected is preferably 180 to 250 ° C., particularly preferably 190 to 220 ° C. When this temperature is less than 180 ° C., the fluidity of the thermoplastic elastomer composition becomes insufficient, and in particular, poor filling may occur at the end portion. On the other hand, when it exceeds 250 ° C., there is a concern about thermal deterioration or the like depending on the composition of the thermoplastic elastomer composition. The mold temperature is preferably 20 to 60 ° C, particularly preferably 30 to 50 ° C. If this temperature is less than 20 ° C., the thermoplastic elastomer composition in contact with the inner surface of the mold is rapidly cooled, and it cannot be made into a homogeneous foamed molded product, and filling failure may occur at the end. is there. On the other hand, when the temperature exceeds 60 ° C., a homogeneous skin layer may not be formed on the portion formed in contact with the surface of the cavity of the foam molded product, which is not preferable.

  In addition, the time from the injection of the thermoplastic elastomer composition to the start of the movable core or the movable core installed in the movable mold (mold retraction delay time) depends on the mold opening speed. It is preferable to set it to 5 seconds or less, and the reverse may be started immediately after completion of the injection. This mold retraction delay time is preferably 0.5 to 3 seconds, particularly preferably 0.5 to 1.5 seconds. If the mold retraction delay time exceeds 5 seconds, cooling may proceed and a homogeneous foam molded product may not be obtained.

  The retraction amount of the mold may be set according to a predetermined foaming ratio, and is not limited. Particularly, in the case of an interior material for a vehicle, the foamed molded product has an initial thickness of the material filled in the cavity space in the mold. It is preferable to retract the mold, that is, open the mold so that the final thickness becomes 1.1 to 5.0 times. If the ratio of the wall thickness is the expansion ratio, the expansion ratio is preferably 1.3 to 3 times, more preferably 1.5 to 2 times, and the thickness of the foamed molded product is 2 to 10 mm, particularly 3 Considering that there are many products that are ˜6 mm, the retraction amount of the mold is usually 0.5 to 4 mm.

  The cooling time depends on the size of the foam molded product or the cooling method, but the temperature of the foam molded product at the time of demolding may be lowered to about 40 to 80 ° C. Well, 100 seconds is sufficient even for large products.

  Hereinafter, the present invention will be described in more detail with reference to examples and comparative examples in the case of manufacturing a glove box lid which is a vehicle interior material.

[1] Production of thermoplastic elastomer composition for core-back injection foam molding Example 1-1
Using each component of the following [1] to [5] in the following mass ratio, a pressure type kneader (manufactured by Moriyama Co., Ltd.) having a capacity of 10 liters, set temperature 150 ° C., kneading time 15 minutes, rotor rotation speed ( After melting and kneading at 32 times / minute (front side) and 28 times / minute (back side), the mixture was pelletized by a feeder ruder (manufactured by Moriyama Co., Ltd.) and used as a thermoplastic elastomer for producing a foam molded product. Furthermore, using this pellet, a sheet having a thickness of 2 mm was formed by an injection molding machine (manufactured by Toshiba Machine Co., Ltd., model “IS-90B”), and observed with a transmission electron microscope. Moreover, JIS-A hardness was measured using this sheet | seat.

The sheet was observed by cutting the sheet in a plane direction with a microtome to form a thin piece, staining the thin piece with RuO ₄ or the like, and then observing it with a transmission electron microscope. It can be clearly seen that a three-dimensional network structure is formed according to FIG. Further, the melt flow rate (MFR) measured by the method described later in Example 1-1 was 16 g / 10 min, the melt tension was 6.7 gf, and the JIS-A hardness was 67.

(1) Blending components and blending amount [1] EAO copolymer (1): Ethylene / propylene / 5-ethylidene-2-norbornene terpolymer (ethylene content; 66% by mass, 5-ethylidene-2- Norbornene content: 4.5% by mass, ML _{1 + 4} (100 ° C.) = 400, mineral oil-based softener (made by Idemitsu Kosan Co., Ltd., trade name “Diana Process Oil PW380”) is contained in 50% by mass. ), Blending amount: 58 parts by mass [2] crystalline polyethylene resin (2): linear low density polyethylene (density: 0.925 g / cm ³ , MFR (temperature 190 ° C., load 2.16 kg); 0.8 g / 10 minutes, manufactured by Nippon Polychem Co., Ltd., trade name “Novatech LLDPE UF423”), blending amount: 17 parts by mass [3] block copolymer (3): hydrogenated diene copolymer described in Table 1, composition The amount; 20 parts by weight (4) crystalline α- olefin copolymer: Propylene - ethylene block copolymer (density; 0.90g ^/ cm 3, MFR (temperature 230 ° C., load of 2.16 kg); 3 g / 10 min , Manufactured by Nippon Polychem Co., Ltd., trade name “Novatech PP BC5CW”), blending amount: 5 parts by mass [5] Anti-aging agent: Ciba Specialty Chemicals, trade name “Irganox 1010”, blending amount: 0.2 parts by weight However, the total of [1], [2], [3] and [4] is 100 parts by mass.

  The foaming agent and the nucleating agent were blended by supplying the master batch prepared as described below to the injection molding machine together with the thermoplastic elastomer prepared as described above. In this way, a thermoplastic elastomer composition for core back type injection foam molding was obtained.

  Foaming agent masterbatch (trade name “Polyslen EE405” manufactured by Eiwa Kasei Co., Ltd., low-density polyethylene containing 40% by mass of sodium bicarbonate and citric acid as inorganic foaming agents in a total amount), A master batch containing a foaming agent and a nucleating agent was prepared by mixing an equal amount of a nucleating agent master batch (8% by mass of calcium carbonate powder in low density polyethylene) in a mass ratio, Pellets were formed in the same manner as in the case of the thermoplastic elastomer.

(2) Physical property evaluation method [1] Melt flow rate (MFR): Measured according to JIS K 7210 at a temperature of 230 ° C. and a load of 10 kg.
[2] Melt tension: Measured with a melt tension tester (manufactured by Toyo Seiki Seisakusho, model “Melt Tension Tester Type II”) at a temperature of 210 ° C., an extrusion speed of 10 mm / min, and a take-up speed of 2 m / min.
[3] JIS-A hardness: A sheet was punched into a predetermined shape with a dumbbell cutter to produce a test piece, and measured according to JIS K 6301.

Example 1-2
Foaming agent masterbatch (manufactured by Eiwa Kasei Co., Ltd., trade name “Polyslen EV309”, low-density polyethylene containing 30% by mass of organic foaming agent azodicarbonamide) and nucleating agent masterbatch (low-density A master batch containing a foaming agent and a nucleating agent was prepared by mixing equal amounts of polyethylene carbonate with calcium carbonate powder in an amount of 6% by mass ratio. A thermoplastic elastomer composition for core-back type injection foam molding was obtained in the same manner as in Example-1.

Example 1-3
Foaming agent master batch (manufactured by Eiwa Kasei Co., Ltd., trade name “Polyslen EE202H”), low density polyethylene, organic foaming agent azodicarbonamide, inorganic foaming agent sodium bicarbonate and citric acid in a total amount of 20 A thermoplastic elastomer composition for core-back type injection foam molding was obtained in the same manner as in Example 1-1 except that it was blended by mass%. In Example 1-3, a nucleating agent is not blended, but sodium carbonate produced from sodium bicarbonate that decomposes in advance functions as a nucleating agent during the decomposition of azodicarbonamide that decomposes later. To do.

Example 1-4
First, each of the following components [1] to [6] was used at a predetermined mass ratio, and a thermoplastic elastomer was obtained in the same manner as in Example 1-1.
[1] EAO copolymer (1): polymer used in Example 1-1, blending amount; 65 parts by mass [2] crystalline polyethylene resin (2): linear high-density polyethylene (Nippon Polyolefin Co., Ltd.) Manufactured, trade name “KMA90K”), blending amount: 10 parts by mass [3] block copolymer (3): hydrogenated diene copolymer described in Table 1, blending amount: 10 parts by mass [4] crystallinity α-olefin copolymer: propylene-ethylene block copolymer used in Example 1-1, blending amount: 10 parts by mass [5] Mineral oil softener: Idemitsu Kosan Co., Ltd., trade name “Diana Process Oil PW -380 ", blending amount: 5 parts by mass [6] Anti-aging agent: manufactured by Ciba Specialty Chemicals, trade name" Irganox 1010 ", blending amount: 0.2 parts by mass However, [1], [2], [ 3], [4] and [5] And parts by weight. The thermoplastic elastomer obtained had an MFR of 50 g / 10 min, a melt tension of 3.4 gf, and a JIS-A hardness of 70.
Using this thermoplastic elastomer, a core-back type injection foam molding thermoplastic elastomer composition was obtained in the same manner as in Example 1-1.

Comparative Example 1-1
In the same manner as in Example 1-1, a partially crosslinked thermoplastic elastomer (manufactured by Sumitomo Chemical Co., Ltd., trade name “TPE4652”) is blended with an inorganic foaming agent and a nucleating agent to obtain a thermoplastic elastomer composition. It was. The MFR measured in the same manner as in Example 1-1 of the partially crosslinked thermoplastic elastomer was 15 g / 10 min, the melt tension was 2.8 gf, and the JIS-A hardness was 57.

Comparative Example 1-2
A thermoplastic elastomer composition was obtained in the same manner as in Example 1-1 except that the nucleating agent master batch was not blended and 3.75 parts by mass of the foaming agent master batch was blended.

[2] Production of base material for glove box lid From polypropylene (trade name “Idemitsu Polypropylene J-762HP” manufactured by Idemitsu Petrochemical Co., Ltd.) containing 10% by mass of talc and 3% by mass of ethylene / propylene copolymer rubber A base material having a thickness of 2.5 mm was produced by injection molding.

[3] Production of glove box lid Examples 2-1 to 4 and Comparative examples 2-1 to 2
After dry blending 100 parts by mass of the thermoplastic elastomer pellets in Examples 1-1 to 4 and Comparative Examples 1-1 and 2 prepared in [1] and 7.5 parts by mass of masterbatch pellets, an injection molding machine ( A glove box lid in which a foam layer (foam molded product) having a thickness of 4 mm is formed on the surface of the base material prepared in [2] as follows. Manufactured.

Hereinafter, the manufacturing method of a glove box lid is demonstrated based on FIG. 2 which described the outline of the process.
As shown in FIG. 2A, the base material 2 was disposed in a part of the cavity space of the mold 1 adjusted to 30 ° C. Thereafter, as shown in FIG. 2B, the thermoplastic elastomer composition 3 having a temperature of 210 ° C. was injected into the other space having a thickness of 2 mm where the substrate 2 in the cavity space was not disposed. The injection was completed in 1.5 seconds, and the thermoplastic elastomer composition 3 was filled in the other part of the cavity space as shown in FIG. After 1 second (core back start time), as shown in FIG. 2 (d), the movable mold 1a is retracted by 2 mm (core back amount) at a speed of 0.3 mm / second (core back speed), and a thermoplastic elastomer composition is obtained. Was foamed and cooled as it was for 60 seconds. Next, as shown in FIG. 2 (e), the mold was opened to obtain a glove box lid in which a foam layer 4 having a thickness of 4 mm (foaming ratio was doubled) was formed on the surface of the substrate 2.

Comparative Example 2-3
A glove box lid was obtained in the same manner as in Example 2-1, except that the mold opening speed was 1 mm / second.

[4] Evaluation of foam layer The cross section of the glove box lid manufactured in [3] was observed with a microscope. As a result, as shown in the explanatory diagrams of the photographs in FIGS. 3 and 4, Example 2-1 has a small difference in average cell diameter between the vicinity of the gate and the end portion and a fine cell having a diameter of 200 μm or less. A foam layer was formed. The average cell diameter (D _g ) in the vicinity of the gate of the foam layer was 98 μm, the average cell diameter (D _e ) at the end was 102 μm, and (D _g / D _e ) was 0.96.

Similarly, in Examples 2-2 to 4, a foamed layer having uniform cells and a fine cell having a diameter of 200 μm or less was formed. In the foamed layers of Examples 2-2 to 4, the cell diameters in the vicinity of the gate were 105 μm, 94 μm, and 98 μm, respectively, and the cell diameters at the ends were 115 μm, 123 μm, and 118 μm, respectively.
On the other hand, as shown in the explanatory diagram of the photograph in FIG. 5, in Comparative Example 2-1, uniform foaming was hindered by the crosslinking reaction, and coarse voids were formed, or cracks were partially generated. Further, as shown in the explanatory diagram of the photograph of FIG. 6, in Comparative Example 2-2, the cells were nonuniform and coarse.

In addition, as shown in the explanatory diagram of the photograph of FIG. 7, in the glove box lid obtained in Comparative Example 2-3, the cell diameter is generally large, particularly at the end portion, and the average cell diameter in the vicinity of the gate of the foam layer ( D _g ) was 210 μm, the average cell diameter (D _e ) at the end was 345 μm, and (D _g / D _e ) was 0.61. Therefore, it was too soft, had a bottom sensation of striking against the substrate, and had a low quality.

  In the present invention, the present invention is not limited to the above-described embodiment, and various modifications can be made within the scope of the present invention. For example, the glove box lid can be manufactured by the following double injection method.

  As shown in FIG. 8A, a mold 1 having a movable mold 1a having a movable core 1b is prepared. Thereafter, as shown in FIG. 8B, the composite material 2 is injected into the cavity space of the mold 1 adjusted to an appropriate temperature, and cooled to form the base material 3. Next, as shown in FIG. 8C, the movable core 1b is moved backward to form a space for injecting the thermoplastic elastomer composition. Thereafter, as shown in FIG. 8D, the thermoplastic elastomer composition 4 having a predetermined temperature is injected into this space. After a predetermined time has elapsed, as shown in FIG. 8 (e), the movable core 1b is retracted at a predetermined mold opening speed, the thermoplastic elastomer composition is foamed and cooled as it is. Next, as shown in FIG. 8 (f), the mold is removed to obtain a glove box lid in which the foamed layer 5 having a predetermined foam ratio is formed on the surface of the substrate 3.

It is explanatory drawing by the photograph of the magnification of 2000 times of the sheet | seat which carried out the injection molding of the thermoplastic elastomer composition for core back type | mold injection foam molding of Example 1-1. It is a schematic diagram of the manufacturing process of a glove box lid. (A) is the state which has arrange | positioned the base material in cavity space. (B) is the state which is injecting. (C) is a state where injection is completed. (D) is a state in which the movable mold is retracted and foamed. (E) is a state in which the mold is opened. It is explanatory drawing by the enlarged photograph by the microscope of the cross section of the glove box lid obtained in Example 2-1. (A) is the gate vicinity of the cross section of the glove box lid obtained in Example 2-1, (b) is explanatory drawing by the enlarged photograph obtained with the microscope of the terminal part. It is explanatory drawing by the enlarged photograph by the microscope of the cross section of the glove box lid obtained by the comparative example 2-1. It is explanatory drawing by the enlarged photograph by the microscope of the cross section of the glove box lid obtained by the comparative example 2-2. (A) is the gate vicinity, (b) is explanatory drawing by the enlarged photograph obtained with the microscope of the terminal part of the cross section of the glove box lid obtained by the comparative example 2-3. It is a schematic diagram of the other manufacturing process of a glove box lid. (A) is a state before a shaping | molding start. (B) is the state after injecting the composite material. (C) is a state in which, after the composite material is cooled and the base material is formed, the movable core is retracted to form a space for injecting the thermoplastic elastomer composition. (D) is a state where injection is completed. (E) is a state in which the movable core is retracted and foamed. (F) is the state which removed.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1; Metal mold | die, 1a; Movable type | mold, 1b; Movable core, 2; Base material, composite material, 3; Thermoplastic elastomer composition, base material, 4; Foamed layer, thermoplastic elastomer composition, 5;

The present invention relates to an injection foam molding method using a thermoplastic elastomer composition for core back type injection foam molding. More specifically, it has a three-dimensional network structure that does not depend on chemical cross-linking, has excellent workability, has high foamability, uniform cell shape and cell diameter, and has sufficient elastic recovery and flexibility. The present invention also relates to an injection foam molding method using a thermoplastic elastomer composition which can be a foam molded article having an excellent appearance. Foam molded products obtained by this method include automotive interior parts such as instrument panels and glove boxes, automotive exterior parts such as weather strips, weak electrical parts, anti-vibration materials for electrical appliances, other industrial parts, building materials, and sporting goods. Etc. can be used.

In recent years, foam molded products have been used in many product fields as cushioning materials and soft tactile components for vibration and noise of automobile interior parts, exterior parts, home appliances, information equipment, and the like. In particular, thermoplastic elastomer compositions have attracted attention as raw materials that are easy to mold and foam easily. Examples of such a thermoplastic elastomer composition include a thermoplastic elastomer composition that can be dynamically cross-linked, and a foam-molded article can be obtained using the thermoplastic elastomer composition disclosed in Patent Document 1 below. Are known.

The present invention solves the above-described problems, and has excellent physical properties such as uniform cell shape and cell diameter, high closed cell properties, low compression set, and good appearance. It is an object of the present invention to provide an injection foam molding method using a thermoplastic elastomer composition for core back type injection foam molding which can obtain a foam molded article having the same.

The present invention achieves the above object, and is exemplified below.
[1] In a matrix comprising an ethylene / α-olefin copolymer (1) and a crystalline polyethylene resin (2), and comprising the ethylene / α-olefin copolymer (1), The crystalline polyethylene resin (2) contains a thermoplastic elastomer constituting a three-dimensional network structure, a foaming agent (4), and a nucleating agent (5), and the thermoplastic elastomer has a temperature of 230 ° C. and a load of 10 kg. melt flow rate is not less 5 g / 10 min or more, and 210 ° C., the melt tension at take-off speed 2m / min is mold core-back injection foaming thermoplastic elastomer composition for Ru der least 3.0gf cavity And then expanding the cavity space by opening the mold with a mold opening speed of 0.05 to 0.4 mm / sec. An injection foam molding method characterized by foaming a product to obtain a foam molded article having a skin layer and a foam layer .
[2] An ethylene / α-olefin copolymer (1), a crystalline polyethylene resin (2), and the following block copolymer (3), the ethylene / α-olefin copolymer A thermoplastic elastomer, a foaming agent (4) and a nucleating agent in which the crystalline polyethylene resin (2) and the block copolymer (3) constitute a three-dimensional network structure in the matrix comprising (1) (5), the thermoplastic elastomer has a melt flow rate of 5 g / 10 min or more at a temperature of 230 ° C. and a load of 10 kg, and a melt tension of at least 3.0 gf at 210 ° C. and a take-up speed of 2 m / min. Core-back type injection foaming thermoplastic elastomer composition is injected into the cavity space in the mold, and then the mold is opened with a mold opening speed of 0.05 to 0.4 mm / sec. An injection foam molding method comprising expanding the cavity space to foam the thermoplastic elastomer composition to obtain a foam molded article having a skin layer and a foam layer .
[Block copolymer (3)]; a block having higher compatibility with the crystalline ethylene polymer block and the ethylene / α-olefin copolymer (1) than with the crystalline polyethylene resin (2). A block copolymer comprising
[3] The foaming agent (4) is a foaming agent-containing resin in which the foaming agent (4) is kneaded into the olefin resin (6), and the nucleating agent (5) The injection foam molding method according to the above [1] or [2], wherein 5) is a nucleating agent-containing resin kneaded into the olefin resin (6).
[4] The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the foaming agent (4) is at least one selected from sodium bicarbonate, ammonium bicarbonate, ammonium chloride, and ammonium carbonate. And [1] to [3], wherein the composition further contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. The injection foam molding method according to any one of the above.
[5] The injection foam molding method according to [1] or [2], wherein the foaming agent (4) is an organic foaming agent (4a) and an inorganic foaming agent (4b) .
[6] The organic foaming agent (4a) and the inorganic foaming agent (4b) are: (i) an organic foaming agent-containing resin in which the organic foaming agent (4a) is kneaded into the olefin resin (6). And an inorganic foaming agent-containing resin in which the inorganic foaming agent (4b) is kneaded into the olefinic resin (6), or (ii) an organic foaming agent (4a) and an inorganic foaming agent (4b) are olefinic resins. An organic / inorganic foaming agent-containing resin kneaded in (6), wherein the nucleating agent (5) is a nucleating agent in which the nucleating agent (5) is kneaded into an olefin resin (6). The injection foam molding method according to the above [5], which is a resin containing.
[7] The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the organic foaming agent (4a) is an azo foaming agent, a nitroso foaming agent, a sulfonyl hydrazide foaming agent, or a triazine. The inorganic foaming agent (4b) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate. The injection foam according to [5] or [6], wherein the composition contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. Molding method .
[8] The injection foam molding method according to any one of [1] to [7], wherein the mold retraction delay time is 0 to 5 seconds after completion of filling.
[9] Claim final thickness of the foam molded article with respect to the initial thickness of the material filled in the mold cavity space is opened mold such that 1.1 to 5.0 times [1] Thru | or the injection foam molding method in any one of [8] .
[10] The injection foam molding method according to any one of [1] to [9] , wherein a foam molded product is formed on the surface of the substrate.

According to the injection foam molding method of the present invention, there is a three-dimensional network structure that does not depend on chemical crosslinking, and this three-dimensional network structure melts and disappears when the melting point is exceeded. By using a thermoplastic elastomer composition for injection and injection foam molding by a core back method at a specific mold opening speed, high foamability, uniform cell shape, small cell diameter, and elastic recovery In addition, a foam molded article having excellent flexibility and appearance can be obtained.
In addition, when an organic foaming agent and an inorganic foaming agent are used in combination, the decomposition product produced by the decomposition of the inorganic foaming agent that decomposes in advance functions as a nucleating agent. There is no need to blend. Furthermore, the combined use can also reduce the content of the organic foaming agent in which the odor remaining in the foamed molded product becomes a problem. In particular, when an inorganic foaming agent and a weakly acidic compound are used in combination, the decomposition rate is increased. In addition, if the particle size of the nucleating agent is 2 to 50 μm, a foam molded product having an appropriate cell diameter and excellent cushioning properties can be obtained .
Further, by specifying the mold retraction delay time and the final thickness of the foam molded product relative to the initial thickness of the material filled in the cavity space in the mold, it is possible to obtain a foam molded product of better quality. . In particular, when a weakly acidic compound is used in combination, the decomposition rate is increased. Further, if a foam molded product is formed on the surface of a substrate made of resin or the like, an interior part such as an automobile made of a laminate of the substrate and the foamed layer can be easily molded.

Claims (20)

An ethylene / α-olefin copolymer (1) and a crystalline polyethylene resin (2), wherein the crystalline polyethylene is contained in a matrix comprising the ethylene / α-olefin copolymer (1). Resin (2) contains a thermoplastic elastomer constituting a three-dimensional network structure, a foaming agent (4) and a nucleating agent (5),
The thermoplastic elastomer has a melt flow rate of 5 g / 10 min or more at a temperature of 230 ° C. and a load of 10 kg, and a melt tension of 210 g at a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back type injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back type injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.   The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the foaming agent (4) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate, The core back injection foam according to claim 1, wherein the composition contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. A thermoplastic elastomer composition for molding. In a matrix comprising an ethylene / α-olefin copolymer (1) and a crystalline polyethylene resin (2) and comprising the ethylene / α-olefin copolymer (1), the crystallinity A thermoplastic elastomer in which the polyethylene resin (2) constitutes a three-dimensional network structure;
A foaming agent-containing resin in which the foaming agent (4) is kneaded into the olefin resin (6);
A nucleating agent (5) is blended with a nucleating agent-containing resin kneaded into the olefin resin (6),
The melt flow rate at a temperature of 230 ° C. and a load of 10 kg of the thermoplastic elastomer is 5 g / 10 min or more, and the melt tension at 210 ° C. and a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back mold injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back mold injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.   The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the foaming agent (4) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate, The core back type injection foam according to claim 3, wherein the composition contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. A thermoplastic elastomer composition for molding. An ethylene / α-olefin copolymer (1), a crystalline polyethylene resin (2), and the following block copolymer (3), the ethylene / α-olefin copolymer (1) A thermoplastic elastomer in which the crystalline polyethylene resin (2) and the block copolymer (3) constitute a three-dimensional network structure, a foaming agent (4), and a nucleating agent (5). Containing
The thermoplastic elastomer has a melt flow rate of 5 g / 10 min or more at a temperature of 230 ° C. and a load of 10 kg, and a melt tension of 210 g at a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back type injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back type injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.
[Block copolymer (3)]; a block having higher compatibility with the crystalline ethylene polymer block and the ethylene / α-olefin copolymer (1) than with the crystalline polyethylene resin (2). A block copolymer comprising   The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the foaming agent (4) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate, The core-back type injection foam according to claim 5, wherein the composition contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. A thermoplastic elastomer composition for molding. An ethylene / α-olefin copolymer (1), a crystalline polyethylene resin (2), and the following block copolymer (3) are contained, and the ethylene / α-olefin copolymer (1 A thermoplastic elastomer in which the crystalline polyethylene resin (2) and the block copolymer (3) constitute a three-dimensional network structure in a matrix comprising
A foaming agent-containing resin in which the foaming agent (4) is kneaded into the olefin resin (6);
A nucleating agent (5) is blended with a nucleating agent-containing resin kneaded into the olefin resin (6),
The melt flow rate at a temperature of 230 ° C. and a load of 10 kg of the thermoplastic elastomer is 5 g / 10 min or more, and the melt tension at 210 ° C. and a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back mold injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back mold injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.
[Block copolymer (3)]; a block having higher compatibility with the crystalline ethylene polymer block and the ethylene / α-olefin copolymer (1) than with the crystalline polyethylene resin (2). A block copolymer comprising   The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the foaming agent (4) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate, The core-back type injection foam according to claim 7, wherein the composition contains at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. A thermoplastic elastomer composition for molding. An ethylene / α-olefin copolymer (1) and a crystalline polyethylene resin (2), wherein the crystalline polyethylene is contained in a matrix comprising the ethylene / α-olefin copolymer (1). The thermoplastic resin (2) comprising a three-dimensional network structure, an organic foaming agent (4a), an inorganic foaming agent (4b) and a nucleating agent (5),
The melt flow rate at a temperature of 230 ° C. and a load of 10 kg of the thermoplastic elastomer is 5 g / 10 min or more, and the melt tension at 210 ° C. and a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back mold injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back mold injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.   The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the organic foaming agent (4a) is an azo foaming agent, a nitroso foaming agent, a sulfonyl hydrazide foaming agent, or a triazine foaming agent. And the tetrazole-based blowing agent, and the inorganic foaming agent (4b) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate. The core back type injection foam molding thermoplastic resin according to claim 9, further comprising at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. Elastomer composition. In a matrix comprising an ethylene / α-olefin copolymer (1) and a crystalline polyethylene resin (2) and comprising the ethylene / α-olefin copolymer (1), the crystallinity A thermoplastic elastomer in which the polyethylene resin (2) constitutes a three-dimensional network structure;
(I) An organic foaming agent-containing resin in which the organic foaming agent (4a) is kneaded into the olefin resin (6) and an inorganic foaming agent in which the inorganic foaming agent (4b) is kneaded into the olefin resin (6) A foaming agent-containing resin, or (ii) an organic / inorganic foaming agent-containing resin in which the organic foaming agent (4a) and the inorganic foaming agent (4b) are kneaded into the olefin resin (6);
A nucleating agent (5) is blended with a nucleating agent-containing resin kneaded into the olefin resin (6),
The melt flow rate at a temperature of 230 ° C. and a load of 10 kg of the thermoplastic elastomer is 5 g / 10 min or more, and the melt tension at 210 ° C. and a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back mold injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back mold injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.   The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the organic foaming agent (4a) is an azo foaming agent, a nitroso foaming agent, a sulfonyl hydrazide foaming agent, or a triazine foaming agent. And the tetrazole-based blowing agent, and the inorganic foaming agent (4b) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate. The thermoplastic resin for core-back type injection foam molding according to claim 11, comprising at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. Elastomer composition. An ethylene / α-olefin copolymer (1), a crystalline polyethylene resin (2), and the following block copolymer (3), the ethylene / α-olefin copolymer (1) A thermoplastic elastomer, an organic foaming agent (4a), an inorganic foam (wherein the crystalline polyethylene resin (2) and the block copolymer (3) constitute a three-dimensional network structure). 4b) and a nucleating agent (5),
The melt flow rate at a temperature of 230 ° C. and a load of 10 kg of the thermoplastic elastomer is 5 g / 10 min or more, and the melt tension at 210 ° C. and a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back mold injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back mold injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.
[Block copolymer (3)]; a block having higher compatibility with the crystalline ethylene polymer block and the ethylene / α-olefin copolymer (1) than with the crystalline polyethylene resin (2). A block copolymer comprising   The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the organic foaming agent (4a) is an azo foaming agent, a nitroso foaming agent, a sulfonyl hydrazide foaming agent, or a triazine foaming agent. And the tetrazole-based blowing agent, and the inorganic foaming agent (4b) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate. Thermoplastic for core back type injection foam molding according to claim 13, comprising at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate and acidic potassium tartrate. Elastomer composition. An ethylene / α-olefin copolymer (1), a crystalline polyethylene resin (2), and the following block copolymer (3) are contained, and the ethylene / α-olefin copolymer (1 A thermoplastic elastomer in which the crystalline polyethylene resin (2) and the block copolymer (3) constitute a three-dimensional network structure,
(I) An organic foaming agent-containing resin in which the organic foaming agent (4a) is kneaded into the olefin resin (6) and an inorganic foaming agent in which the inorganic foaming agent (4b) is kneaded into the olefin resin (6) A foaming agent-containing resin, or (ii) an organic / inorganic foaming agent-containing resin in which the organic foaming agent (4a) and the inorganic foam (4b) are kneaded into the olefin resin (6);
A nucleating agent (5) is blended with a nucleating agent-containing resin kneaded into the olefin resin (6),
The melt flow rate at a temperature of 230 ° C. and a load of 10 kg of the thermoplastic elastomer is 5 g / 10 min or more, and the melt tension at 210 ° C. and a take-off speed of 2 m / min is 3.0 gf or more,
After injecting the thermoplastic elastomer composition for core back mold injection foam molding into the cavity space in the mold, the cavity space is expanded by opening the mold, and the thermoplastic elastomer composition for core back mold injection foam molding is expanded. A core-back type thermoplastic elastomer composition for injection foam molding, which is used to obtain a foam molded article having a skin layer and a foam layer.
[Block copolymer (3)]; a block having higher compatibility with the crystalline ethylene polymer block and the ethylene / α-olefin copolymer (1) than with the crystalline polyethylene resin (2). A block copolymer comprising   The nucleating agent (5) is an inorganic compound powder having a particle size of 2 to 50 μm, and the organic foaming agent (4a) is an azo foaming agent, a nitroso foaming agent, a sulfonyl hydrazide foaming agent, or a triazine foaming agent. And the tetrazole-based blowing agent, and the inorganic foaming agent (4b) is at least one selected from sodium hydrogen carbonate, ammonium hydrogen carbonate, ammonium chloride, and ammonium carbonate. The core-back type injection foam molding thermoplastic resin according to claim 15, further comprising at least one weakly acidic compound selected from oxalic acid, malonic acid, citric acid, lactic acid, boric acid, monosodium citrate, and acidic potassium tartrate. Elastomer composition.   The core back type injection foaming thermoplastic elastomer composition according to any one of claims 1 to 16 is injected into a cavity space in a mold, and thereafter a mold opening speed of 0.05 to 0.4 mm / sec. An injection foam molding method comprising: expanding a cavity space by opening a mold to foam the thermoplastic elastomer composition to obtain a foam molded article having a skin layer and a foam layer.   18. The injection foam molding method according to claim 17, wherein a mold retraction delay time is 0 to 5 seconds after completion of filling.   18. The injection foaming according to claim 17, wherein the mold is opened so that a final thickness of the foamed molded product is 1.1 to 5.0 times an initial thickness of a material filled in the cavity space in the mold. Molding method.   The injection foam molding method according to claim 17, wherein a foam molded product is formed on the surface of the substrate.