JPH08283443A - Foamed and molded product of thermoplastic elastomer - Google Patents

Abstract

PURPOSE: To obtain the subject molded product good in the balance between flexibility and abrasion resistance, excellent in rubber elastic modulus, mechanical strength, heat resistance, appearance, and touch, and capable of shortening the molding cycle. CONSTITUTION: The foamed and molded product of a thermoplastic elastomer is produced by compounding 100 pts.wt. of a thermoplastic elastomer with (D) 0.1-50 pts.wt. of a resin composition containing a heat-absorbing foaming agent starting its decomposition reaction at a temperature of >=160 deg.C and subsequently injection-foaming the mixture. The thermoplastic elastomer is produced by subjecting (A) 100 pts.wt. of syndiotactic polypropylene, (B) 50-450 pts.wt. of an ethylene-propylene copolymer rubber and (C) 5-350 pts.wt. of a softening agent to a crosslinking reaction in the presence of an organic peroxide. The foamed molded product is utilized especially for inner parts in automobiles.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a thermoplastic elastomer.
Of the foamed molded article. More specifically, it has a particularly good balance of flexibility and wear resistance, rubber elasticity, mechanical strength,
The present invention relates to a foamed molded article of a thermoplastic elastomer, which is excellent in heat resistance, moldability, appearance and feel and is particularly suitable for automobile parts.

[0002]

BACKGROUND OF THE INVENTION Olefinic thermoplastic elastomers are
For example, it is widely used as an important material mainly in the field of industrial materials such as automobiles and light electric appliances. This is because when the ethylene-propylene rubber is mixed with the isotactic polypropylene resin, it is expected that the feel, flexibility, rubber elasticity and the like of the isotactic polypropylene can be improved. However, for example, if the amount of ethylene-propylene rubber compounded in the isotactic polypropylene resin is increased to improve the flexibility, the flexibility can be improved, but the abrasion resistance and the heat resistance are improved. ,
Moldability tends to decrease. In addition, in both automobile-related and light-electric related fields, while maintaining the required flexibility and abrasion resistance, the surface appearance is not impaired by heating during molding, and a beautiful, undeformed material is used. Is required.

[0003]

DISCLOSURE OF THE INVENTION An object of the present invention is to provide excellent flexibility as long as abrasion resistance is equivalent to that of isotactic polypropylene prepared by blending a conventional ethylene-propylene rubber, It is an object of the present invention to provide a foamed molded article of a thermoplastic elastomer which is excellent in abrasion resistance if the flexibility is the same. Another object of the present invention is that, in addition to having the above-mentioned properties, the surface appearance of the molded product is also beautiful, and for example, foam molding of a thermoplastic elastomer as a material suitable for the fields of automobiles, weak electric currents, etc. To provide things.

[0004]

Means for Solving the Problems The present inventor has conducted earnest research to achieve the above-mentioned object, and found that syndiotactic polypropylene, ethylene-propylene-non-conjugated diene copolymer rubber and a softening agent were used as organic compounds. A thermoplastic elastomer excellent in flexibility, rubber elasticity, mechanical strength and surface appearance can be obtained by crosslinking while being melt-kneaded in the presence of a peroxide or a crosslinking aid with it, and further, an endothermic foaming agent. It was found that a foamed molded product excellent in flexibility and rubber elasticity can be obtained by blending and injection molding a resin composition containing the above, and completed the present invention. That is, the present invention is 100 parts by weight of syndiotactic polypropylene (A), 50 to 450 parts by weight of ethylene-propylene rubber (B), and 5 to 3 of softening agent (C).
A resin composition (D) containing 100 parts by weight of a thermoplastic elastomer obtained by crosslinking 50 parts by weight in the presence of an organic peroxide and an endothermic foaming agent which starts a decomposition reaction at 160 ° C. or higher.
The present invention relates to a foamed molded article of a thermoplastic elastomer obtained by compounding 1 to 50 parts by weight and injection-foaming.

The present invention will be described in detail below. The syndiotactic polypropylene used in the present invention may be syndiotactic homopolypropylene,
It may be a syndiotactic polypropylene copolymer which is a copolymer of propylene and α-olefin.
The syndiotactic pentad ratio determined by ¹³ C-NMR is 0.5 or more in the case of syndiotactic homopolypropylene, preferably 0.7 or more,
0.75 or more is particularly preferable. In the case of syndiotactic polypropylene copolymer, the syndiotactic pentad fraction of the propylene chain is 0.3 or more, preferably 0.5 or more, particularly preferably 0.7 or more.

The comonomer used in the syndiotactic polypropylene copolymer used in the present invention is preferably an α-olefin other than propylene. α-
Examples of the olefin include ethylene, 1-butene, and 3
-Methyl-1-butene, 1-hexene, vinylcyclohexene, 1-decene, 1-hexadecene, cyclopentene, olefins such as norbornene, hexadiene, octadiene, decadiene, dicyclopentadiene, 5-
Examples thereof include copolymers containing dienes such as ethylidene 2-norbornene. Such a copolymer is preferably obtained by copolymerizing propylene and a comonomer in the presence of a known catalyst capable of giving a poly-α-olefin having good syndiotacticity.
The content ratio of the comonomer cannot be specified because it varies depending on the comonomer, but is usually 1 to 30% by weight, preferably 5 to 1
It is 5% by weight. The molecular weight of syndiotactic polypropylene is 0.1 to 10 dl / g, preferably 0.5 as the intrinsic viscosity measured in a tetralin solution at 135 ° C.
˜5.0 dl / g.

The catalyst for producing syndiotactic polypropylene in the present invention is, for example, JP-A-2-4.
No. 1303, No. 2-41305, No. 2-274703, No. 2-274704, No. 3-179005, No. 3-179.
Examples of the catalyst include a bridged transition metal compound having asymmetric ligands and a cocatalyst as described in JP-A-006-69394 and JP-A-4-69394, but catalysts having different structures. Even ¹³ C-NM
Any polypropylene capable of producing a polypropylene having a syndiotactic pentad fraction measured by R of 0.5 or more can be used.
Both the bulk polymerization method and the gas phase polymerization method can be used.

The ethylene-propylene rubber used in the present invention is used for further improving rubber elasticity and flexibility such as compression set and permanent elongation of the resin. The ethylene-propylene rubber is not particularly limited as long as it is a rubber containing ethylene and propylene, but an ethylene-propylene copolymer rubber having an ethylene content of 50 to 85% by weight (hereinafter abbreviated as EPR), Ethylene content 5
0 to 85% by weight of ethylene-propylene-non-conjugated diene copolymer rubber (hereinafter abbreviated as EPDM) or a mixture thereof is preferable. In order to further promote crosslinking, it is more preferable to use EPDM containing a diene component.

Examples of the non-conjugated diene monomer used in EPDM include non-conjugated dienes having 5 to 20 carbon atoms, cyclic dienes and alkenyl norbornenes. Carbon number 5
Examples of the non-conjugated diene of ~ 20 include 1,4-hexadiene and 1,4-octadiene, and examples of the cyclic diene include cyclohexadiene, cyclooctadiene and dicyclopentadiene. Also,
Examples of alkenylnorbornene include 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, 2-isopropenyl-5-norbornene and the like. Among these, those using 5-ethylidene-2-norbornene or dicyclopentadiene are preferable, and the content thereof is 4 to 30% by weight. The Mooney viscosity of ethylene-propylene rubber is 10
10 to 180 at 0 ° C and ML _{1 + 4} is desirable,
Particularly preferably, it is 40 to 140, and the weight average molecular weight is 200,000 to 400,000. When the Mooney viscosity is less than 10, the mechanical strength is insufficient, and when it exceeds 180, the fluidity is poor and the moldability is poor.

The blending amount of the ethylene-propylene rubber is 50 to 450 parts by weight, preferably 100 to 400 parts by weight, based on 100 parts by weight of syndiotactic polypropylene. If it is less than 50 parts by weight, the rubber elasticity will be insufficient, and if it exceeds 450 parts by weight, the fluidity will be poor and the moldability will be poor. The softening agent used in the present invention may be any of a paraffin type, a naphthene type and an aromatic type, but a paraffin type process oil is most suitable in terms of hue, odor and the like. The compounding amount is 5 to 350 parts by weight with respect to 100 parts by weight of syndiotactic polypropylene,
It is preferably 10 to 250 parts by weight, particularly preferably 1
5 to 200 parts by weight. If the amount is less than 5 parts by weight, the flexibility, rubber elasticity and fluidity will be insufficient, and if the amount is more than 350 parts by weight, the mechanical strength will be lowered. Paraffin-based process oil or the like has the same blending amount when the ethylene-propylene rubber added in advance is used.

In the present invention, an organic peroxide is used to crosslink a composition comprising syndiotactic polypropylene, ethylene-propylene rubber and a softening agent to obtain a thermoplastic elastomer. Examples of the organic peroxide include dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di- (t-
Butylperoxy) hexane, 2,5-dimethyl-2,
5-di- (t-butylperoxy) hexyne-3,1,
3-bis (t-butylperoxyisopropyl) benzene, 1,1-bis (t-butylperoxy) -3,3,3
5-trimethylcyclohexane, n-butyl-4,4-
Bis (t-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-
Examples thereof include butyl peroxybenzoate, t-butyl perbenzoate, t-butyl peroxyisopropyl carbonate, diacetyl peroxide, lauroyl peroxide, t-butyl cumyl peroxide. Of these, 2,5-dimethyl-2,5-di- (t-butylperoxy) hexane is particularly preferable in terms of odor and scorch stability.

The amount of the organic peroxide added is not particularly limited, but is preferably 0.1 to 10 parts by weight, and 0.2 to 10 parts by weight with respect to 100 parts by weight of syndiotactic polypropylene.
5 parts by weight is more preferred. If the addition amount is less than 0.1 parts by weight, crosslinking may not be sufficiently performed, and rubber properties such as strain recovery and impact resilience and mechanical strength may be inferior.
On the other hand, if it exceeds 10 parts by weight, the molecular weight of the syndiotactic polypropylene may be remarkably lowered, the mechanical strength may be lowered, or the fluidity of the thermoplastic elastomer may be lowered due to excessive crosslinking.

In the present invention, a crosslinking aid may be used when crosslinking with an organic peroxide. As the crosslinking aid used, N, N′-m-phenylene bismaleimide,
Peroxide crosslinking aids such as p-quinonedioxime, p, p'-dibenzoylquinonedioxime, diphenylguanidine, trimethylolpropane-N, N'-m-phenylene dimaleimide, or divinylbenzene, triallyl isocyanate Examples thereof include polyfunctional vinyl monomers such as nurate, ethylene glycol dimethacrylate, trimethylolpropane trimethacrylate and allyl methacrylate. The amount of addition is preferably equal to or twice the amount of the organic peroxide. If it is added in excess of 2 times the amount, the crosslinking reaction will proceed excessively and the fluidity will decrease, resulting in poor moldability, and more unreacted monomer remaining in the composition.

The thermoplastic elastomer obtained by crosslinking with the above-mentioned peroxide or a crosslinking aid with the peroxide has not only higher tensile and tear strengths than the thermoplastic elastomer obtained by ordinary melt-kneading, but also It has a rubber-like property with low surface hardness and small permanent elongation, and has an excellent balance of physical properties. Whether or not it is cross-linked depends on whether the thermoplastic elastomer of the present invention is boiled in boiling xylene for 4 hours or more and then filtered through a 400-mesh wire mesh to obtain a residue of 10 parts by weight with respect to 100 parts by weight of the blended rubber component. It is determined by whether or not the above.

The thermoplastic elastomer used in the present invention is syndiotactic as long as the flexibility, abrasion resistance, mechanical strength, moldability, heat resistance, chemical resistance, appearance and feel of the molded product are not significantly deteriorated. Resins or rubbers other than tic polypropylene, ethylene-propylene rubber and softening agents may be used. For example, isotactic homopolypropylene, isotactic ethylene-propylene block copolymer, isotactic ethylene-propylene random copolymer, ethylene-butene rubber, propylene-butene rubber, ethylene-octene rubber, styrene-butadiene diblock copolymer. Hydrogenated product, styrene-butadiene-styrene triblock copolymer hydrogenated product, styrene-isoprene diblock copolymer hydrogenated product, styrene-isoprene-styrene triblock copolymer hydrogenated product, low density Polyethylene, high density polyethylene, linear low density polyethylene, ultra low density polyethylene, ethylene-ethyl acrylate copolymer,
Examples thereof include ethylene-vinyl acetate copolymer and polybutene resin. The amount used is not particularly limited, but is preferably 1 to 50 parts by weight with respect to 100 parts by weight of the composition of the present invention.

Further, in producing the thermoplastic elastomer used in the present invention, a filler in a range that does not impair the fluidity and rubber elasticity of the thermoplastic elastomer,
For example, calcium carbonate, calcium silicate, talc, silica, mica, alumina, barium sulfate, aluminum sulfate, calcium sulfate, graphite, glass fiber, glass beads, carbon fiber, etc., relative to 100 parts by weight of the thermoplastic elastomer used in the present invention. 1 to 50 parts by weight may be added. Further, if necessary, various additives such as an antiblocking agent, a lubricant, a crystal nucleating agent, an ultraviolet absorber, a heat stabilizer, a radiation resistant agent, a dye and a pigment may be added. The compounding amount thereof is usually 0.001 to 1 part by weight with respect to 100 parts by weight of the composition of the present invention.

The thermoplastic elastomer used in the present invention can be produced by melt-kneading using a Banbury mixer, a pressure kneader, a twin screw extruder or the like.
For example, when a twin-screw extruder is used, the materials other than the softening agent are mixed together in a Henschel mixer, and then the softening agent is melt-kneaded while being injected into the extruder by a flanger pump. Any of a method in which materials other than the oxide and the crosslinking aid are mixed together by a Henschel mixer or the like, and then the softening agent, the organic peroxide and the crosslinking aid are melt-kneaded while being injected into the extruder by a flanger pump. Can also be used. The melting and kneading temperature is preferably 180 to 220 ° C. The thermoplastic elastomer used in the present invention is prepared by blending a resin composition containing an endothermic foaming agent and performing injection foam molding for the purpose of improving flexibility, molding cycle, and weight reduction of molded products. It can be a foam molded article.

The resin composition containing an endothermic foaming agent (hereinafter abbreviated as a foaming agent masterbatch) used in the present invention means 1 to 1 parts of the endothermic foaming agent with respect to 100 parts by weight of the resin.
It can be easily produced by blending 100 parts by weight and melt-kneading using a known machine such as a pressure kneader, a Banbury mixer, a single-screw extruder or a twin-screw extruder. The melt-kneading temperature is set to 160 in consideration of the decomposition start temperature of the endothermic foaming agent.
It is preferably produced at a temperature of not higher than 0 ° C. The thermoplastic resin used for producing the blowing agent masterbatch used in the present invention includes melt flow index (2
30g, 2.16kg load, hereinafter translated as MFI) 2g
/ 10 minutes or more, preferably 10 g / 10 minutes or more, and particularly preferably 20 g / 10 minutes or more can be used. M
If the FI is less than 2 g / 10 minutes, the fluidity may be low, and formulation may be difficult. The higher the MFI, the better the dispersed state of the foaming agent.

Preferred types of thermoplastic resins include propylene homopolymers, copolymers of propylene and α-olefins such as propylene-ethylene copolymers, propylene-butene copolymers, propylene-ethylene-butene ternary. Copolymers can be used. Further, ethylene-butene copolymer, ethylene-octene copolymer, low density polyethylene, high density polyethylene, linear low density polyethylene, ultra low density polyethylene, ethylene-ethyl acrylate copolymer, ethylene-vinyl acetate copolymer. Examples thereof include polymers, styrene-butadiene block copolymers, styrene-butadiene-styrene triblock copolymers, styrene-isoprene-diblock copolymers, styrene-isoprene-styrene triblock copolymers and polybutene resins. Moreover, in order to improve MI, you may use the polypropylene resin which added the organic peroxide previously and made the molecular weight fall.

The endothermic foaming agent used for producing the foaming agent masterbatch used in the present invention is, for example, a mixture of a polycarboxylic acid and an inorganic carbonic acid compound, etc., and prevents the adsorption of moisture on the surface thereof. Therefore, those treated with monoglyceride, stearic acid, a silane compound (silane coupling agent, etc.), etc. are also included. Here, as the polycarboxylic acid, saturated dicarboxylic acids such as citric acid, fumaric acid and tartaric acid, unsaturated dicarboxylic acids, and salts thereof with Ca, Mg, Na and the like, sodium citrate hydride, citric acid 1 Sodium and the like are also included.
Inorganic carbonate compounds include alkali metal and alkaline earth metal carbonate compounds such as sodium aluminum bicarbonate, sodium bicarbonate, and the like, and mixtures thereof. The endothermic foaming agent is not limited to these, but those having a decomposition temperature of 160 to 300 ° C. are preferable as the foaming agent in the injection molding machine. In the present invention, the blowing agent masterbatch is used in an amount of 1 to 50 parts by weight, preferably 5 to 20 parts by weight, based on 100 parts by weight of the crosslinked thermoplastic elastomer. If it is less than 1 part by weight, the effect of reducing flexibility and weight is small, and if it exceeds 50 parts by weight, the surface appearance of the product may be rough or pinholes may occur.

The thermoplastic elastomer foam-molded product of the present invention is prepared by blending the above-mentioned thermoplastic elastomer and the blowing agent masterbatch, and using a mold in which sufficient degassing is provided at the fluid terminal of the resin. It can be easily obtained by injection molding. In addition, a gas injection molding method in which nitrogen gas or the like is introduced into a plasticized composition using the foam molding method, or a gas counter pressure for a thick molded product having a wall thickness of about 4 to 20 mm. The foamed molded article of the present invention can also be obtained by a method, further, an injection stamping (injection press, low pressure molding) method or the like in which the plasticized composition is injected, or after the injection, the mold is closed and molded. The unfoamed part, the wall thickness of the foamed part, and the size of the foam cell are adjusted by controlling the foaming, and if the amount of the foaming agent is too large, the unfoamed part disappears, and the appearance has pores, Causes a phenomenon of being rough.

The foamed molded article of the thermoplastic elastomer of the present invention has an average wall thickness of 0.3 to 50 mm, preferably 2 to 25.
mm. When the average wall thickness is less than 0.3 mm, when the blend of the thermoplastic elastomer composition and the resin composition is filled in the mold by the injection molding method, the pressure loss is large and the cooling rate is fast, so that the fluidity is high. Is suppressed and short-circuit is likely to occur. On the other hand, when it exceeds 50 mm, since the molding holding pressure is not applied, the foamed cells shrink and the molded product is liable to sink.

The foamed molded article of the thermoplastic elastomer of the present invention preferably has an unfoamed portion and a foamed portion in common, and more preferably has a structure having a foamed layer between the unfoamed layers. 1 and 2 schematically show the structure of the foamed molded product. FIG. 1 schematically shows a cross section of the foamed molded product having a curved surface, and FIG. 2 schematically shows a cross section of the rectangular foamed molded product.
1 of FIG. 1 and FIG. 2 shows a foamed portion, and 2 shows an unfoamed portion. In this structure, the relationship between the wall thickness X of the unfoamed portion, the wall thickness Y of the foamed portion, and the wall thickness Z of the foamed molded article preferably has a relationship of Z = 2X + Y, 2X ≦ Y. In the case of 2X> Y, since there are few foamed parts, the effects of flexibility, molding cycle and weight saving are small. The size of the foam cell is preferably less than 160 μm. When it exceeds 160 μm, flexibility, impact strength, etc. are lowered, which is not preferable.

The thickness of the unfoamed portion, the thickness of the foamed portion, and the size of the foamed cells are determined by scanning an electron microscope (SEM: Scanning Electron Mi).
It can be easily measured by observing with "croscope".

[0025]

EXAMPLES The following examples are provided for illustrating the present invention further in detail, but the present invention is not limited thereto. The measuring methods in the examples are as follows, and the physical properties are shown in Tables 1 to 4. (1) Hardness: JIS K6301 (2) Abrasiveness of JIS: JIS K7204 Evaluated by the value of weight loss due to wear Test conditions: 1 kg load, 1000 rotations, type of worn wheel H-18 (3) Tensile breaking strength , Elongation: JIS K6301 (4) Young's modulus: JIS K6301 (5) Appearance: No silver, sink marks or pinholes are observed on the surface of the molded product. / ○ Some silver and sink marks are seen on the surface of the molded product. / △ Silver, sink marks and pinholes are seen on the surface of the molded product. / × (6) Thickness of foam layer, size of foam cell: Measured by observing with a scanning electron microscope (SEM). (7) Molding cycle: After confirming that the molded product did not have any twist, warp, or sag, the process time from injection to holding pressure to cooling to removal (molded product) was measured.

Examples 1 to 5 In a tetralin solution at 135 ° C. obtained by carrying out bulk polymerization in the presence of hydrogen using a catalyst consisting of diphenylmethylene (cyclopentadienyl) fluorenylzirconium dichloride and methylaluminoxane. The intrinsic viscosity (hereinafter abbreviated as [η]) measured by 1.39 dl
/ G, MI is 3.2 g / 10 min, peak temperature of crystallization temperature measured by differential scanning calorimetry is 74.6 ° C., ¹³ C
-Syndiotactic homopolypropylene (SPP-1) having a syndiotactic pentad fraction of 0.787 determined by NMR, and ethylene-propylene-non-conjugated diene copolymer rubber according to the compositions shown in Tables 1 and 2 (Manufactured by Japan Synthetic Rubber Co., Ltd., EP98A: contains 75 parts by weight of a softening agent paraffinic process oil), 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as a crosslinking agent, a crosslinking auxiliary agent Was mixed with divinylbenzene and a known stabilizer to obtain a thermoplastic elastomer at a kneading temperature of 180 ° C. in a pressure kneader (manufactured by Moriyama Seisakusho Co., Ltd.). This thermoplastic elastomer
A polypropylene-based blowing agent masterbatch (ACTIVEX 536: manufactured by JM Huber Co., Ltd.) containing citric acid and sodium carbonate as an endothermic blowing agent was mixed in a tumbler. Using an injection molding machine (M20), a square flat plate mold having a length of 150 mm, a width of 150 mm, and a thickness of 3 mm having a gate at one center in the vertical direction is used.
0-AII: manufactured by Meiki Seisakusho Co., Ltd., and molded at a nozzle side of 180 ° C. and a cylinder side of 220 ° C. as preset temperatures to obtain a foamed molded product. The experimental results are shown in Table 1.

Comparative Examples 1 to 3 Molded products were obtained in the same manner as in Examples 1 to 3 except that the polypropylene-based blowing agent masterbatch was not used.
The experimental results are shown in Table 2. In all of Comparative Examples 1 to 3, the molding cycle was long, and in Comparative Example 3, some silver and sink marks were observed on the surface of the molded product.

Comparative Example 4 A thermoplastic elastomer produced without using an organic peroxide and a cross-linking aid was used, and a blowing agent masterbatch was not used. It was The experimental results are shown in Table 2. The molding cycle was long, and no flexibility was felt in the obtained molded product.

Comparative Example 5 A molded product was obtained in the same manner as in Example 1 except that the thermoplastic elastomer produced without using the organic peroxide and the crosslinking aid was used. The experimental results are shown in Table 2. No softness was felt in the obtained molded product.

Comparative Example 6 Example 1 except that the amount of blowing agent masterbatch was increased.
A molded product was obtained in the same manner as in. The experimental results are shown in Table 3. The appearance of the molded product was very poor because the foaming proceeded excessively.

Comparative Example 7 A molded product was obtained in the same manner as in Example 1 except that the amount of the ethylene-propylene-non-conjugated diene copolymer rubber was reduced when producing the thermoplastic elastomer. The experimental results are shown in Table 3. No flexibility was felt in the obtained molded product.

Comparative Example 8 A molded product was obtained in the same manner as in Example 1 except that the amount of the ethylene-propylene-non-conjugated diene copolymer rubber was increased during the production of the thermoplastic elastomer. The experimental results are shown in Table 3. Due to the large amount of rubber, the flowability was poor and a large loss occurred in the molding cycle.

Comparative Example 9 In producing a thermoplastic elastomer, an isotactic random polypropylene (manufactured by Mitsui Toatsu Chemicals, Inc .: MJS-G, MFI1. 5g / 10mi
n, ethylene content 2.6% by weight, hereinafter referred to as IPP-1. A molded product was obtained in the same manner as in Example 1 except that The experimental results are shown in Table 3.

[0034]

[Table 1]

[0035]

[Table 2]

[0036]

[Table 3]

[0037]

The thermoplastic elastomer foamed product of the present invention has a particularly good balance of flexibility and abrasion resistance, and is excellent in rubber elasticity, mechanical strength, heat resistance, moldability, appearance and feel. Since the molding cycle is shortened, the product can be finished at low cost. The foamed molded product of the present invention is particularly suitably used for automobile interior parts.

[Brief description of drawings]

FIG. 1 is a schematic view of a foamed molded product having a curved surface according to the present invention.

FIG. 2 is a schematic view of a foamed molded product having a rectangular shape of the present invention.

[Explanation of symbols]

 1 Foamed part 2 Unfoamed part

Claims (4)

[Claims] 1. Syndiotactic polypropylene (A) 100 parts by weight, ethylene-propylene rubber (B) 50-450 parts by weight, and softener (C) 5-3.
A resin composition (D) containing 100 parts by weight of a thermoplastic elastomer obtained by crosslinking 50 parts by weight in the presence of an organic peroxide and an endothermic foaming agent which starts a decomposition reaction at 160 ° C. or higher (D).
A foamed molded product of a thermoplastic elastomer obtained by compounding 1 to 50 parts by weight and injection-foaming. 2. The foamed molded article according to claim 1, wherein the ethylene-propylene rubber (B) is an ethylene-propylene copolymer rubber, an ethylene-propylene-non-conjugated diene copolymer rubber, or a mixture thereof. 3. The foamed molded product has a structure having a foamed layer between unfoamed layers, and the thickness X of the unfoamed layer and the thickness Y of the foamed layer are relative to the thickness Z of the foamed molded product. , Z = 2X + Y, 2X
The foamed molded article according to claim 1, having a relationship of ≤Y. 4. The size of the foam cells in the foam portion is 200.
The foamed molded product according to claim 1, wherein the foamed molded product has a thickness of at most μm.