JPH09157426A - Production of olefin-based thermoplastic elastomer injection molded foamed body - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject foamed body which is highly expanded, having uniform and dense foam, exhibiting good soft feeling and useful as an interior part for automobiles by injecting an olefinic thermoplastic elastomer having a specific composition and properly operating the cavity volume. SOLUTION: An elastomer comprising (A) 100 pts.wt. olefinic thermoplastic elastomer obtained by dynamically heat-treating (i) 25-70wt.% ethylene-propylene- diene terpolymer rubber containing an ethylene-propylene-diene terpolymer rubber having 340-385 Mooeny viscosity and 2-6 ratio of weight-average molecular weight Mw to number-average molecular weight and a mineral oil-based softening agent in an amount of 45-150 pts.wt. based on 100 pts.wt. ethylene- propylene-diene terpolymer, (ii) 15-5wt.% polyisobutylene and/or isobutylene- isoprene copolymer rubber and (iii) 60-25wt.% propylene-α-olefin copolymer resin having 2-20wt.% α-olefin content, 0.1-10g/10min melt flow rate and 3-10 Mw/Mn in the presence of an organic peroxide and (B) 1-10 pts.wt. foaming agent is injected and subjected to expansion molding.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing an injection-foam molded article using an expandable olefin-based thermoplastic elastomer obtained by adding a foaming agent to an olefin-based thermoplastic elastomer. An injection-foam molded product used as a skin for interior parts and the like, which has a good soft feeling, a high-quality appearance, and particularly good mold transferability, and also has a skin layer (skin layer) and a pad (foam layer). The present invention relates to a method for producing an olefin-based thermoplastic elastomer injection foamed molded article which is excellent in productivity and recyclability because it is made of the same resin.

[0002]

2. Description of the Related Art Conventionally, automobile interior parts such as an instrument panel, a door trim, a console lid, and a pillar garnish have been required to have a soft feeling in order to have a high-grade feeling. As a structure of a conventional soft interior material, it is general to use different resins for the skin layer and the pad layer in combination. As a typical example of such a soft interior material, a material obtained by laminating a pad layer of polyurethane foam or polypropylene on a skin material of polyvinyl chloride can be mentioned. Further, as a method for producing such a soft interior material, after preforming a polyvinyl chloride sheet by powder slush or vacuum forming, a method of pouring a liquid urethane between the substrate and polyvinyl chloride, A method of integrally molding a base resin on a laminated sheet of polyvinyl chloride and expanded polypropylene by injection compression molding is known.

[0003]

However, the interior parts for automobiles obtained by these materials and construction methods are difficult to recycle because they contain plural kinds of resins, and moreover, there are many steps in production. The problem is that production efficiency is low. As a method for improving the recyclability, the skin material is changed from polyvinyl chloride to an olefinic thermoplastic elastomer, foamed polypropylene obtained by extrusion molding is applied to the pad layer, and further, it is obtained by injection molding on the base material. It is conceivable to apply polypropylene. A method of foaming an olefin-based thermoplastic elastomer during injection molding and applying it to the pad layer is also conceivable. Although a molded product with low foaming can be obtained by such a method, a good soft feeling as an automobile interior material is required. A high foamed product that is produced cannot be obtained. In addition, as a method for simplifying the number of steps, JP-A-63-254015 and JP-A-1-2-2
Two-color molding is known as disclosed in Japanese Patent Publication No. 49416 and the like. However, although these methods are effective in simplifying the process, they cannot obtain the soft feeling required for the interior materials for automobiles obtained by the conventional method. Although each of the above methods is effective as a method for solving each individual problem, it has not been possible to achieve improvement in product quality and simplification of the process at the same time.

[0004]

The present inventor has conducted extensive studies in view of the above problems, and as a result, injects an olefinic thermoplastic elastomer (TPO) having a specific composition and appropriately controls the cavity volume. This has led to the completion of the present invention based on the finding that an injection-foam molded article that solves the above problems can be obtained. That is, in the method for producing an olefin-based thermoplastic elastomer injection foamed molded article of the present invention, the following components (A), (B) and (C) are dynamically heat treated in the presence of an organic peroxide. A foamable olefinic thermoplastic elastomer obtained by mixing 1 to 10 parts by weight of a foaming agent with 100 parts by weight of the obtained olefinic thermoplastic elastomer is injected into a cavity of a molding die to expand the volume of the cavity. It is characterized by performing foam molding. Component (A): Mooney viscosity (ML _{1 + 4} (100 ° C.)) of 340 to 385 and the ratio (Mw /) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) measured by gel permeation chromatography (GPC). Mn) 2 to 6 ethylene-propylene-diene copolymer rubber 100 parts by weight, ethylene-propylene-diene copolymer rubber containing a mineral oil-based softener in a proportion of 45-150 parts by weight: 25- 70% by weight, preferably 45-60% by weight Component (B): polyisobutylene and / or isobutylene-isoprene copolymer rubber: 15-5% by weight, preferably 10-6% by weight Component (C): Propylene / α-olefin copolymer resin satisfying physical properties: 60 to 25% by weight, preferably 45 to 34% by weight α-olefin content: 2 20 wt%, preferably 7 to 17 wt% melt flow rate (MFR): 0.1~10g / 10 min preferably. 1 to 5 g / 10 min Mw / Mn: 3 to 10 preferably 4 to 7

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION

[I] Raw materials (1) Olefin-based thermoplastic elastomer The olefin-based thermoplastic elastomer (TPO) used in the method for producing an olefin-based thermoplastic elastomer injection-foam molded article of the present invention comprises a component (A) and a component ( It is basically composed of B) and the component (C). Component (A): ethylene / propylene / diene copolymer rubber The ethylene / propylene / diene copolymer rubber in the component (A) has a Mooney viscosity (ML _{1 + 4} (100 ° C.)) of 34.
It is 0 to 385, preferably 360 to 380. When the Mooney viscosity (ML _{1 + 4} (100 ° C.)) is less than the above range, the expansion ratio of the foamed molded article is lowered, and the soft feeling is impaired. Further, if it exceeds the above range, moldability is deteriorated. The ethylene / propylene / diene copolymer rubber in the component (A) has a ratio (Mw / Mn) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) of 2 measured by gel permeation chromatography (GPC). -6, preferably 3-4.5. If the Mw / Mn is less than the above range, the molding appearance and softness are deteriorated. On the other hand, if the amount exceeds the above range, the appearance and softness of the molding will be significantly reduced.

The average molecular weight of the component (A) is measured (GPC measurement conditions) by the gel permeation chromatography (Gel Permeation Chromatgr) shown below.
aphy: GPC). Gel Permeation Chromatography Sample Preparation Orthodichlorobenzene 2,6 as an antioxidant
Add 0.08% of di-tert-butyl-cresol (for EPDM) and dissolve. Polypropylene (P
In case of P), 0.1% is added. The sample is placed in a vial with 0.1% ortho-dichlorobenzene solvent. The vial is heated to 135 ° C (for EPDM) to dissolve. 140 ° C for polypropylene (PP)
Warm to. The solvent is run on GPC.

[GPC measurement conditions] EPDM PP device Waters type 150C type Waters type 150C column Tosoh Corp. H type Shodex AD-806MS type Sample amount 500 μl 200 μl Temperature 135 ° C. 140 ° C. Flow rate 1 ml / min 1 ml / min Solvent Orthoge Chlorobenzene Orthodichlorobenzene

Examples of the diene component include 5-ethylidene norbornene, dicyclopentadiene, 1,4-hexadiene and the like. Such a copolymer rubber can be appropriately selected and used from commercial products.

Mineral oil-based softeners Specific examples of the mineral oil-based softener blended in the copolymer rubber of the component (A) having the above physical properties include paraffin-based and naphthene-based softeners, which are mainly soft or elastic. It is used for the purpose of increasing. For example, Mitsubishi 20 Light Process Oil (manufactured by Mitsubishi Oil Co., Ltd.) as a paraffin-based softening agent and Diana Process Oil N as a naphthene-based softening agent.
S-24 (made by Idemitsu Kosan Co., Ltd.) is commercially available. The blending amount of the mineral oil-based softening agent is ethylene / propylene /
The amount is 45 to 150 parts by weight, preferably 75 to 100 parts by weight, based on 100 parts by weight of the diene copolymer rubber. If the mineral oil-based softening agent is less than the above range, flexibility, elasticity and moldability will be reduced. Further, if it exceeds the above range, flexibility, elasticity and moldability are deteriorated.

Component (B): polyisobutylene or isobutene
Tylene / isoprene copolymer rubber Polyisobutylene or isobutylene of the above component (B)
The isoprene copolymer rubber can be appropriately selected and used from commercial products. When the content of the component (B) is less than the above range, the balance of flexibility, hardness and mechanical properties of the molded product is lost. If it exceeds the above range, the balance of flexibility, hardness and mechanical properties of the molded product is lost.

Component (C): Propylene / α-olefin
Copolymer Resin Composition As the α-olefin of the propylene / α-olefin copolymer resin of the above component (C), ethylene, butene-
1, hexene-1, etc. can be mentioned. Of these, ethylene is preferable.

Physical properties Physical properties of the component (C) are within the above range. The component (C) has an influence on the hardness, and when it exceeds the above range, the hardness increases to become a resin and the soft feeling is impaired. On the other hand, if it is less than the above range, the hardness becomes small and the scratch resistance and the mechanical properties are deteriorated. When the α-olefin content of the component (C) is less than the above range, the required flexibility and mechanical properties cannot be obtained. Further, if it exceeds the above range, the required flexibility and mechanical properties cannot be obtained. When the MFR of the component (C) is less than the above range, the required flexibility and mechanical properties cannot be obtained. Further, if it exceeds the above range, the required flexibility and mechanical properties cannot be obtained. If the Mw / Mn of the component (C) is less than the above range, the required flexibility and mechanical properties cannot be obtained. Further, if it exceeds the above range, the required flexibility and mechanical properties cannot be obtained. If the blending amount of the component (C) is less than the above range, the bubble shape and the surface appearance will be deteriorated. Also,
If it exceeds the above range, the feel is deteriorated.

(2) Additional component (arbitrary component of olefin-based thermoplastic elastomer) In the olefin-based thermoplastic elastomer composition used in the olefin-based thermoplastic elastomer injection foam molding of the present invention, the above-mentioned component (A) is included. In addition to the essential components of the component (C), additional components such as the following component (D) and component (E) may be added within a range that does not significantly impair the effects of the present invention or in order to further improve the performance. Ingredients (optional ingredients) can be included.

Component (D): Inorganic filler (a) type In addition to the above olefinic thermoplastic elastomer (TPO),
Examples of the inorganic filler of component (D) to be added as an optional component include, for example, calcium oxide, magnesium oxide, silica, titanium oxide, aluminum hydroxide, magnesium hydroxide, calcium hydroxide, basic magnesium carbonate,
Examples thereof include calcium carbonate, barium sulfate, talc, clay, diatomaceous earth, zeolite and mica.

(B) Blending amount The blending amount of the inorganic filler is 1 to 10 parts by weight based on 100 parts by weight of the olefinic thermoplastic elastomer (TPO).
A range of 3 to 6 parts by weight is preferable. As a particularly preferred specific example, the average particle size is substantially 0.005.
Calcium carbonate having a water content of 0.45% or less at .about.0.15 .mu.m, especially colloidal calcium carbonate, which prevents secondary agglomeration of particles and has an affinity for polymers. When the compounding amount of the inorganic filler contained in TPO is less than the above range, the molded body is likely to be deformed (surface irregularity) due to the shrinkage stress of the surface layer of the molded body. Further, if it exceeds the above range, the synthesis is improved and the deformation amount is reduced, but the impact strength tends to be lowered.

Component (E): Other compounding components As an olefin resin which is an optional component, for example, a homopolymer such as low density polyethylene, medium / high density polyethylene, polypropylene or the like, or ethylene and propylene, butene- 1, a copolymer with hexene-1 and the like. Also, as other additional ingredients,
For example, additives, specifically, plasticizers or fluidity improvers such as paraffin oil, olefin liquid rubber, softeners such as conjugated diene liquid rubber, colorants, antioxidants, Examples thereof include neutralizing agents, light stabilizers, cross-linking agents, nucleating agents and flame retardants. Further, the physical properties of the above olefinic thermoplastic elastomer (TPO) are such that the melt tension at a temperature of 190 ° C. is 2.0 g or more, preferably 1
5-30g Hardness JIS-A is 30 or more, preferably 40-7
0, particularly preferably 50 to 65, elastic modulus of 1,000 to 8,000 kg / c at 23 ° C.
m ² , preferably 4,000 to 7,000 kg / cm ²
The ones that show the physical property values of have the rigidity and strength required for instrument panels such as automobile interior parts, door trims, console boxes, etc., have excellent surface softness and scratch resistance, have high hardness, and have a good appearance. A uniform foamed molded product is obtained.

(3) Organic Peroxide Organic Peroxide (Peroxide) The organic peroxide (hereinafter, simply referred to as “peroxide”) used in the method for producing an olefinic thermoplastic elastomer injection-foam molded article of the present invention. Abbreviated) is obtained by crosslinking a part or all of the ethylene / propylene / diene copolymer rubber contained in the olefin-based thermoplastic elastomer,
It is blended in order to cure it in a semi-crosslinked state. The organic peroxide (peroxide) may be aromatic or aliphatic, and may be a single peroxide or a mixture of two or more peroxides. Specifically, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, t-butyl Peroxybenzoate, dicumyl peroxide, t-
Butyl cumyl peroxide, diisopropyl benzohydroperoxide, benzoyl peroxide, etc. can be mentioned.

Crosslinking Auxiliary Agents which may be used in combination with the above-mentioned peroxides include acrylic polyfunctional monomers such as ethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane triacrylate, divinylbenzene, There are liquid polybutadiene and the like.

Amount Used The amount of the peroxide or crosslinking aid used is generally 0.1 to 3 parts by weight of peroxide (100 parts by weight of the mixture of the components (A) to (C)). Preferably 0.1
-1 part by weight) Crosslinking aid: 0.1-5 parts by weight (preferably 0.1)
However, in practice, it is determined in consideration of the degree of crosslinking which affects the quality of the elastomeric composition obtained. In addition, it is generally preferable to set the amount of the crosslinking aid to be 1 to 3 times the molar ratio of peroxide.

(4) Foaming Agent Foaming Agent As the foaming agent used for foaming the olefinic thermoplastic elastomer used in the method for producing the olefinic thermoplastic elastomer injection foamed molded article of the present invention, a physical foaming agent and a chemical foaming agent are used. It is known that there are foaming agents. Specifically, as a physical foaming agent, inorganic air, nitrogen gas, carbon dioxide gas, organic hydrocarbons, chlorinated hydrocarbons,
CFCs and the like can be mentioned. Chemical foaming agents are also classified into inorganic type and organic type, but there are some types that generate gas by thermal decomposition and some generate gas by reaction. Examples of the chemical foaming agent include inorganic foaming agents typified by sodium bicarbonate and organic foaming agents such as azodicarbonamide, dinitrosopentamethylenetetramine, and 4,4'-oxybis (benzenesulfonylhydrazide). These are generally called pyrolytic chemical foaming agents and are powdery in nature. In the present invention, it is particularly preferable to use a mixed system of a combination of an inorganic filler represented by baking soda and azodicarbonamide (ADCA).

Foaming Aid A foaming aid can be added to aid the foaming of the foaming agent. Examples of the foaming aid include zinc compounds such as zinc stearate and zinc acetate, urea-based auxiliaries, other metal compounds and organic compounds.

(5) Production of olefin-based thermoplastic elastomer To produce the olefin-based thermoplastic elastomer of the present invention, the following two steps are usually carried out, but kneading and heat treatment are performed simultaneously in one step. You can also do it. (a) First step (kneading step) In the first step, the components (A) to (C) or the components (A) to (D) and / or the component (E) are kneaded.
As the kneading method, the method and conditions usually used for rubber, plastic and the like can be adopted. For the kneading, for example, a single screw extruder, a twin screw extruder, a roll,
A Banbury mixer or various kneaders are used.

(B) Second Step (Heat Treatment Step) In the second step, the mixture composition obtained in the first step is heat treated by adding an organic peroxide and optionally a crosslinking agent or an antioxidant. This is a step of partially crosslinking by means of a kneading method using a Banbury mixer, an extruder or the like. Therefore, especially when a Banbury mixer is used, there is an advantage that the first step and the second step can be continuously performed. The degree of crosslinking (% by weight) of the partially crosslinked elastomeric composition obtained according to the present invention was determined by wrapping 1 g of a sample in a wire mesh of 80 mesh and extracting it with boiling xylene for 10 hours using a Soxhlet extractor. 1 g of solid weight sample
Expressed as a ratio to. The preferred degree of crosslinking in the present invention is 5 to 70% by weight, especially 10 to 6% by weight in the above measured values.
It is 0% by weight, most preferably in the range of 15 to 50% by weight. Below the above range, the high temperature compression strain of the obtained elastomer tends to be deteriorated. On the other hand, if the amount exceeds the above range, the moldability tends to deteriorate, and at the same time, the mechanical strength and elongation tend to decrease. The foaming agent is generally dry blended with a V blender or the like at the time of molding.

[II] Molding (1) Molding Method The olefin-based thermoplastic elastomer injection foam-molded product of the present invention is obtained by injecting a foamable olefin-based thermoplastic elastomer into a cavity in which a mold for injection molding is closed. Then, after the injection is completed, the movable die is moved while maintaining the contact with the wall surface of the die due to the expansion of the resin by the foaming gas, and the movable die is stopped at the preset reference wall thickness position for molding. After the cooling of the mold is completed, the movable mold is retracted to take out the product. By such foam molding, it is possible to obtain an olefin-based thermoplastic elastomer injection foam molded article having high foaming and uniform closed cells. Further, the olefin-based thermoplastic elastomer injection foam-molded article of the present invention is obtained by injecting the expandable olefin-based thermoplastic elastomer into the cavity in which the injection molding die is in the mold closed state, and after the injection is completed, the resin by foaming gas is used. The movable mold is moved while maintaining contact with the mold wall surface by the expansion of, and the movable mold is stopped at a position exceeding a preset reference wall thickness position, and then,
After moving the movable die from the position exceeding the reference wall thickness position to the reference wall thickness position for compression and molding, after cooling is completed,
By retracting the movable mold and taking out the product,
It is possible to obtain an injection-foamed molded product having high foaming and uniform closed cells.

(2) Combination Molding The olefinic thermoplastic elastomer injection foam molding of the present invention can be provided with a substrate on the back surface by combining with an existing injection molding method. As the existing injection molding method, a two-color molding method, an insert molding method and the like can be considered. Two-color molding In the two-color molding method, after molding a hard resin molded product that becomes the base resin, then injection foam molding is performed, so that the base made of hard resin adheres to the olefin thermoplastic elastomer injection foam molded product. A composite molded product is obtained. Various resins can be used as the hard resin used as the base resin, but by using a propylene-based resin (homopolymer and block copolymer) similar to the olefin-based thermoplastic elastomer as the base resin, Since these resins have good compatibility with each other, good adhesiveness with the olefinic thermoplastic elastomer injection-foam molded article can be obtained without using an adhesive or the like, which is preferable. Further, if the base resin layer and the skin layer (skin layer) are formed of the same type of resin, the productivity is good and the recyclability is also excellent.

Insert Molding Method In the insert molding method, a hard resin molded product as a base resin is molded in advance, and this is placed in an injection molding die, and then injection foam molding is performed to form a base material for an injection foam molded article. A composite molded body having a close contact is obtained. Good adhesion can be obtained by using a polypropylene resin as the base resin.

[0027]

The present invention will be described more specifically with reference to the following experimental examples. However, the present invention is not limited to these experimental examples. [I] Evaluation method (1) Foaming ratio (times) The specific gravity of the unfoamed molded product was divided by the specific gravity obtained from the volume and weight of the foamed molded product. (2) JIS-A hardness Conforms to JIS-K6301 (JIS-A hardness) (3) Feeling (sensory test) Try pressing the foamed molded product with your finger, and use the "N14 (1992) type pulsar interior material Those having the same soft feeling as the ment panel were judged to be good, and those having a hard feeling or having a bottom feeling on the substrate were judged to be poor.

(4) Bubble shape (visual observation) The foamed molded article is cut and the cross section of the skin layer is visually observed. As a result, it is preferable to have a uniform fine cell structure (cell). When the air bubbles were coarse, or when they were lenticular and non-uniform, they were regarded as defective. (5) Surface Appearance The surface appearance of the foamed molded product was visually observed and judged according to the following criteria. Good: Surface irregularities, sink marks, silver marks, etc. are not noticeable and extremely small. Bad: The above-mentioned appearance defects are conspicuous. Extremely poor: The surface is greatly deformed and the silver mark is severe. (6) Stickiness The stickiness and the appearance change immediately after molding were evaluated as good, and the stickiness was evaluated as bad.

[II] Raw materials The following raw materials were used. (1) Raw material ingredient (A) -1: Ethylene / propylene / diene copolymer rubber (propylene content 27% by weight, Mooney viscosity ML)
_{1 + 4} (100 ° C.) 380, Mw / Mn 3.5, iodine value 19) 100 parts by weight of paraffinic softener 100 parts by weight Component (A) -2: ethylene / propylene / diene copolymer rubber (propylene) 29% by weight, Mooney viscosity ML
_{1 + 4} (100 ° C.) 345, Mw / Mn 5.9, iodine value 9) 100 parts by weight of paraffinic softener 100 parts by weight Component (A) -3: ethylene / propylene / diene copolymer rubber (propylene) 28% by weight, Mooney viscosity ML
_{1 + 4} (100 ° C.) 300, Mw / Mn 3,6, iodine value 15) 100 parts by weight of which contains 75 parts by weight of a paraffinic softener Component (A) -4: ethylene / propylene / diene copolymer rubber (propylene) 27% by weight, Mooney viscosity ML
_{1 + 4} (100 ° C.) 79, Mw / Mn 3.6, iodine value 1
9) 100 parts by weight of 50 parts by weight of paraffinic softener Component (A) -5: ethylene / propylene / diene copolymer rubber (propylene content: 37% by weight, Mooney viscosity ML)
_{1 + 4} (100 ° C.) 137, Mw / Mn 2.8, iodine value 15) Component (B): Isobutylene / isoprene copolymer rubber (“Butyl 1365” manufactured by JSR Corporation)

Component (C) -1: Propylene / ethylene block copolymer (ethylene content 17% by weight, density 0.8)
9 g / cm ³ , MFR (230 ° C) 1.0 g / 10 minutes,
Flexural modulus 4,300 kg / m ² , Mw / Mn 5.4) Component (C) -2: Propylene / ethylene random copolymer (ethylene content 3.2% by weight, density 0.90 g / cm
³ , MFR (230 ° C.) 1.8 g / 10 min, flexural modulus 6,300 kg / m ² , Mw / Mn 5.4) Component (C) -3: propylene / ethylene block copolymer (ethylene content 3.5 % By weight, density 0.90 g / cm
³ , MFR (230 ° C.) 3.0 g / 10 min, flexural modulus 7,500 kg / m ² , Mw / Mn 12.0) Component (C) -4: propylene homopolymer (density 0.90
g / cm ³ , MFR (230 ° C.) 5.0 g / 10 min, flexural modulus 12,000 kg / m ² , Mw / Mn 6.0) component (D): calcium carbonate (average particle diameter 0.15)
(μm, water content 0.4 wt% or less)

(2) Organic peroxide: 2,5-dimethyl-
2,5-Di (t-butylperoxy) hexane (3) Crosslinking aid: Divinylbenzene (4) Foaming agent Foaming agent A: Inorganic foaming agent masterbatch (foaming agent concentration 20% by weight) (Mitsubishi Chemical Corporation) Made "Fine Blow
S20N ") Foaming agent B: azodicarbonamide masterbatch (foaming agent concentration 25% by weight) (" Fineblow B111 "manufactured by Mitsubishi Chemical Corporation)

[III] Experimental Examples Examples 1 to 9 and Comparative Examples 1 to 11 Manufacture of hard resin moldings Mechanical properties, heat resistance, durability, weather resistance and the like required for automobile interior parts can be satisfied. Polypropylene resin with inorganic filler (MFC31 manufactured by Mitsubishi Chemical Corporation)
4) is manufactured by Toshiba Corporation IS170 below at a molding temperature of 220.
Molded using the following box at ℃, the shape is vertical 200mm
A hard resin molded product having a width of 350 mm and a thickness of 2 mm was manufactured.

Kneaded product of olefinic thermoplastic elastomer
Manufacture of the raw materials for the components (A), (B), (C) and (D) described in "(1) Raw materials" above
The ingredients were blended in the proportions shown in 3 and melt-kneaded with a Banbury mixer at a temperature of 180 ° C. for 7 minutes to produce an olefin-based thermoplastic elastomer kneaded product.

Expandable olefinic thermoplastic elastomer
The above-mentioned organic peroxide (0.3 parts by weight) and the above-mentioned crosslinking aid (0.4 parts by weight) were added to 100 parts by weight of the above-mentioned olefinic thermoplastic elastomer, and the product was manufactured by Ikegai Tekko KK In addition to the olefin-based thermoplastic elastomer that has been melt-kneaded and heat-treated with a shaft extruder, the above-mentioned "(4)
4 parts by weight of each of the foaming agent A and the foaming agent B described in "Blowing agent" were dry blended with a V blender to produce a foamable olefin-based thermoplastic elastomer.

Mold expansion method foam injection molding A hard resin molded product of the above shape is mounted in the mold for foam injection molding described below by the mold expansion method using a press roll manufactured by Toshiba Corp. Foam molding was performed under the conditions. That is, after the expandable olefinic thermoplastic elastomer is injected into the cavity between the molding die and the hard resin molded article in the cavity of the molding die, the volume of the cavity is expanded to expand the expandable olefinic thermoplastic elastomer. At the same time when the elastomer is foam-molded, it is integrated with the hard resin molded product of the base material by heat fusion and cooled sufficiently, and then the two-layer injection molding taken out from the mold is continuously performed for 12 shots. Was evaluated. The evaluation results are shown in Tables 1 to 3.

[Mold Enlargement Method Foam Injection Molding Conditions] Molding machine: Toshiba Corporation IS170 (mold clamping force: 170 TON) Mold: Box shape (outer dimensions are 200 mm length × 350 mm width × 28 mm depth) Plate thickness The mold can be expanded from 1 mm to MAX 10 mm. Molding conditions: Molding temperature (220 ° C.) Mold temperature (60 ° C.) Injection time (1.0 to 2.0 sec) Cooling time (30 seconds) Injection speed (MAX) Mold opening timing (Perform under optimum conditions) Mold Opening stroke (3 mm) Mold opening throating (1.2 mg / sec)

[0037]

[Table 1]

[0038]

[Table 2]

[0039]

[Table 3]

[0040]

EFFECT OF THE INVENTION In the method for producing an olefinic thermoplastic elastomer injection foamed molded article of the present invention, a foamable olefinic thermoplastic elastomer having a specific composition is injected, and the cavity volume is appropriately controlled for foaming. Due to the high foaming, uniform and dense cells show a good soft feeling, good fluidity at the time of melting, good mold transferability, and complicated shapes are required. Even in the molding of a large L / D shape, short shots and flow marks are unlikely to occur, the flexibility is excellent, the gloss is good, and a high quality appearance is exhibited, so that it can be used as an interior part for automobiles. Furthermore, since the skin layer (skin layer) and the pad (foam layer) are made of the same resin, it is possible to obtain an olefin-based thermoplastic elastomer injection foam molded article having excellent productivity and recyclability.

Continuation of front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical indication location B29K 105: 04 (72) Inventor Ryumi Tsuji 1 Toho-cho, Yokkaichi-shi, Mie Mitsubishi Chemical Co., Ltd. Yokkaichi Research Institute In-house (72) Inventor Kazuo Yajima 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd. (72) Inventor Toru Ogawa 2 Takara-cho, Kanagawa-ku, Yokohama, Kanagawa (72) Invention Masa Terada Hiroshi Tera 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa 2 Nissan Motor Co., Ltd. (72) Inventor Kosuke 2 Takaracho, Kanagawa-ku, Yokohama, Kanagawa Nissan Motor Co., Ltd.

Claims (5)

[Claims] 1. 1 to 10 parts by weight of 100 parts by weight of an olefinic thermoplastic elastomer obtained by dynamically heat treating the following components (A), (B) and (C) in the presence of an organic peroxide. An olefinic thermoplastic elastomer characterized by injecting an expandable olefinic thermoplastic elastomer containing a part by weight of a foaming agent into a cavity of a molding die and expanding the volume of the cavity for foaming. A method for producing an injection foam molded article. Component (A): Mooney viscosity (ML _{1 + 4} (100 ° C.)) of 340 to 385 and the ratio (Mw /) of the weight average molecular weight (Mw) and the number average molecular weight (Mn) measured by gel permeation chromatography (GPC). Mn) 2 to 6 ethylene-propylene-diene copolymer rubber 100 parts by weight, ethylene-propylene-diene copolymer rubber containing a mineral oil-based softener in a proportion of 45-150 parts by weight: 25- 70% by weight Component (B): Polyisobutylene and / or isobutylene / isoprene copolymer rubber: 15 to 5% by weight Component (C): Propylene / α-olefin copolymer satisfying the following physical properties Resin: 60 to 25 wt% α-olefin content: 2 to 20 wt% Melt flow rate: 0.1 to 10 g / 10 minutes Mw / Mn: 3 to 10 2. The olefin according to claim 1, wherein the expandable olefin-based thermoplastic elastomer contains an inorganic filler in a ratio of 1 to 10 parts by weight with respect to 100 parts by weight of the olefin-based thermoplastic elastomer. Method for producing a thermoplastic elastomer injection foamed molded article. 3. The foamable olefinic thermoplastic elastomer according to claim 1 or 2 is injected into a cavity in a mold closed state of an injection molding machine, and after the injection is completed, the elastomer is expanded by a foaming gas to form a mold wall surface. Of the olefinic thermoplastic elastomer injection-foam molded article according to claim 1 or 2, wherein the movable die is moved while maintaining the contact between the two, and the foaming is performed by stopping the movable die at a preset reference wall thickness position. Production method. 4. The foamable olefinic thermoplastic elastomer according to claim 1 or 2 is injected into a cavity in a mold closed state of an injection molding machine, and after the injection is completed, the elastomer is expanded by a foaming gas to form a mold wall surface. The movable die is moved while maintaining the contact between the movable die and the movable die, and the movable die is stopped at a position exceeding the preset reference wall thickness position, and then the movable die is advanced from the position exceeding the reference wall thickness position to set the reference wall thickness position. The method for producing an olefin-based thermoplastic elastomer injection-foam molded article according to claim 1 or 2, wherein foam molding is performed by applying compression to the temperature. 5. A hard resin molded product is previously mounted in a cavity of a molding die, claim 1, claim 2, and claim 3.
Alternatively, the method for producing an olefin-based thermoplastic elastomer injection foamed molded article according to claim 4.