JP2000072907A - Expanded material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an olefinic thermoplastic elastomer compsn. expanded material, soft and excellent in the balance of properties; mechanical characteristic, weatherability, processability, etc. SOLUTION: This expanded material is prepared by expanding a thermoplastic elastomer compsn. which is prepared by partly or completely crosslinking a mixture comprising 1-99 pts.wt. ethylene/α-olefin copolymer (A) comprising ethylene and 6-12C α-olefin and manufactured using a metallocene catalyst, and 1-99 pts.wt. polypropylene resin (B) (where total of (A) and (B) are 100 pts.wt.), and the degree of crosslinking of ethylene/α-olefin copolymer is not less than 50% and the degree of swelling is 5-40%.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a foam of an olefin-based thermoplastic elastomer composition having a specific structure, and more particularly, to a balance between physical properties such as mechanical strength, weather resistance and processability. The present invention relates to a foam of an olefin-based thermoplastic elastomer having excellent heat resistance.

[0002]

2. Description of the Related Art Polyurethane foams have been widely used as cushioning materials for various chairs and beds, shock absorbing materials, highly flexible materials, and the like, since they can be made into flexible and high-magnification foams.

[0003] However, in recent years, with increasing awareness of environmental issues, the importance of less problems in waste disposal and recyclability has become important, and harmful gases may be generated during incineration. Polyurethane foams, which have poor recyclability, are being reviewed as materials having problems.

A radically crosslinkable olefin elastomer and a thermoplastic resin having no radical crosslinkability, such as polypropylene, are melt-kneaded in a kneader such as an extruder in the presence of a radical initiator to crosslink the elastomer components. Olefinic thermoplastic elastomers by mechanical cross-linking have attracted attention because of their high flexibility, excellent rubber-like properties, and ease of various molding processes, and there has been an increasing movement to use these materials as substitutes. ing.

However, the olefin-based thermoplastic elastomer obtained by the dynamic cross-linking is generally poor in foaming property, the mechanical strength of the foamed product is low, and a practical product has not been easily obtained.

Observation of the micro morphology of the olefinic thermoplastic elastomer by dynamic crosslinking shows that the two layers of the thermoplastic resin as the matrix and the crosslinked elastomer as the islands are intricately interlocked with each other. When a thin film is formed, the mechanical strength and the like may decrease.

[0007] On the other hand, various attempts have been made to foam the thermoplastic elastomer composition. For example, JP-A-9-157426 discloses that ethylene-propylene-diene copolymer rubber and polyisobutylene and / or
Alternatively, a foam of an olefin thermoplastic elastomer comprising an isobutylene / isoprene copolymer rubber and a propylene / α-olefin copolymer resin is disclosed, but the mechanical strength is insufficient.

[0008]

SUMMARY OF THE INVENTION An object of the present invention is to provide an olefin having an excellent balance of physical properties such as mechanical strength, weather resistance, and processability, which cannot be obtained with conventional olefin-based thermoplastic elastomer foams. An object of the present invention is to provide a foam of a thermoplastic elastomer.

[0009]

Means for Solving the Problems The present inventors have conducted intensive studies in order to solve the above-mentioned problems, and as a result, using an olefin-based copolymer having a specific structure consisting of ethylene and α-olefin, The present inventors have found that the problem can be solved by using an olefin-based thermoplastic elastomer composition by dynamic crosslinking having a crosslinked structure, and completed the present invention.

That is, the present invention relates to (A) an ethylene / α-olefin copolymer 1 comprising ethylene and an α-olefin having 6 to 12 carbon atoms, which is produced using a metallocene catalyst.
(B) partially or completely crosslinked with a mixture of (B) 1 to 99 parts by weight of the propylene resin (the total amount of (A) and (B) is 100 parts by weight); A) The degree of crosslinking of the ethylene / α-olefin copolymer is 5
A foam obtained by foaming a thermoplastic elastomer composition having 0% or more and a swelling degree of 5 to 40%.

[0011]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, the present invention will be described in detail.

(A) The ethylene / α-olefin copolymer comprises ethylene and at least one or more carbon atoms having 6 to 1 carbon atoms.
2 is a copolymer composed of α-olefin.

Examples of the α-olefin having 6 to 12 carbon atoms include hexene-1, 4-methylpentene-1,
Heptene-1, octene-1, nonene-1, decene-
1, undecene-1, dodecene-1 and the like. Among them, hexene-1, 4-methylpentene-1 and octene-1 are preferred, and octene-1 is particularly preferred.
Octene-1 is excellent in softening effect even in a small amount, and the obtained copolymer is excellent in mechanical strength.

(A) The ethylene / α-olefin copolymer can be produced using a known metallocene catalyst.

Generally, the metallocene-based catalyst comprises a cyclopentadienyl derivative of a group IV metal such as titanium or zirconium and a co-catalyst, and is not only highly active as a polymerization catalyst but also a conventional catalyst such as a Ziegler-based catalyst. In comparison, the molecular weight distribution of the obtained polymer is narrow, and the distribution of the comonomer α-olefin having 6 to 12 carbon atoms in the copolymer is uniform. Therefore, the properties of the ethylene / α-olefin copolymer produced by the metallocene-based catalyst are greatly different from those of the conventional one using a Ziegler-based catalyst or the like.

The characteristics of an olefin copolymer composed of ethylene and an α-olefin using a metallocene polymerization catalyst are listed below. Since the polymerization catalyst has high activity, the composition of the comonomer α-olefin can be greatly increased as compared with the conventional one, and an elastomeric polymer having high flexibility can be obtained even without a plasticizer.

2. The comonomer distribution is uniform compared to Ziegler-based polymers. Therefore, the reaction site can be uniform in the crosslinking reaction.

3. Compared with Ziegler-based polymers, the molecular weight distribution is extremely sharp, the amount of low molecular weight components is extremely small, the mechanical strength and workability are excellent, and the quality is high.

4. When a long-chain branch is introduced, despite the sharp molecular weight distribution, ASTM D123
Melt index (I10) at 190 ° C./10 kgf specified by No. 8 and 190 ° C./2.16 kg
f to the melt index (I2) (I10
/ I2) has a large value and is excellent in processing characteristics.

[5] Contains no diene component and has excellent environmental degradation resistance.

6. Even if the α-olefin copolymerization ratio is high, blocking hardly occurs and a pellet-like form is possible. And so on.

In the case of an olefin copolymer which is a copolymer of ethylene and an α-olefin using a Ziegler catalyst, the above-mentioned melt index ratio (I10 / I2) and molecular weight distribution show a substantially linear proportional relationship. The molecular weight distribution tends to increase as the ratio increases. The molecular weight distribution is usually about 3 to 10.

On the other hand, in the case of an olefin polymer using a metallocene catalyst, the molecular weight distribution becomes a sharp value of less than 3.0 and the amount of low molecular weight components is extremely small irrespective of the value of the melt index ratio. For this reason, workability is extremely excellent.

The molecular weight distribution (Mw / Mn) of these olefinic elastomers is calculated by GPC.

(A) The ethylene / α-olefin copolymer preferably has an α-olefin copolymerization ratio of 1 to 60% by weight, more preferably 20 to 60% by weight.
Most preferably, it is 30 to 60% by weight. If the copolymerization ratio of the α-olefin exceeds 60% by weight, the mechanical strength of the composition tends to decrease and it is difficult to use the composition practically. On the other hand, if it is less than 1% by weight, the flexibility tends to be insufficient. is there.

[0026] The density of (A) an ethylene · alpha-olefin copolymer, preferably in the range of 0.8 to 0.9 g / cm ^3, further in the range of 0.80~0.86g / cm ³ Preferably, there is.

When the copolymerization ratio is as high as possible and the density can be lowered so as not to lower the mechanical strength, the amount of the matrix can be increased and the foaming moldability is improved, which is desirable.

(A) The ethylene / α-olefin copolymer preferably has a long chain branch. The presence of the long-chain branch enables the density to be lower than the ratio (% by weight) of the copolymerized α-olefin without lowering the mechanical strength. hardness,
A high-strength elastomer can be obtained. The olefin elastomer having a long chain branch is described in US Pat. No. 5,278,272 and the like.

The (A) ethylene / α-olefin copolymer preferably has a DSC melting point peak at room temperature or higher. When it has a melting point peak, the form is stable in the temperature range below the melting point, the handleability is excellent, and the stickiness is small.

The melt index of (A) the ethylene / α-olefin copolymer is 0.01 to 100 g /
Those having a range of 10 minutes (190 ° C., 2.16 kg load) are preferably used, and more preferably 0.2 to 10 g / 1.
0 minutes. If the amount exceeds 100 g / 10 minutes, the crosslinking property of the thermoplastic elastomer composition tends to be insufficient,
If it is less than 0.01 g / 10 minutes, the fluidity is poor, and the processability tends to decrease.

As the ethylene / α-olefin copolymer (A), a plurality of types may be mixed and used. In such a case, it is possible to further improve the workability.

In the present invention, the propylene resin (B) may be, for example, a homo isotactic polypropylene or an isotactic propylene of propylene with another α-olefin such as ethylene, butene-1, pentene-1, hexene-1. Base resin (including block and random) and the like, and a plurality of types may be mixed and used.

The melt index of the propylene resin (B) is 0.1 to 100 g / 10 min (230 ° C.,
2.16 kg load) is preferably used. If it exceeds 100 g / 10 minutes, the mechanical strength such as the heat resistance and the adhesive strength of the composition tends to decrease.
If it is shorter than / 10 minutes, the fluidity is poor and the moldability tends to decrease.

The composition of the present invention comprises (A) ethylene.α-
1 to 99 parts by weight of the olefin copolymer and 1 to 99 parts by weight of the propylene resin (B) [the total amount of (A) and (B) is 10
0 parts by weight]. Preferably (A) ethylene α
-10 to 90 parts by weight of olefin copolymer and 10 to 90 parts by weight of (B) propylene resin, more preferably 20 to 80 parts by weight of (A) ethylene / α-olefin copolymer and (B) propylene resin 20 ８０80 parts by weight.
When the content of the propylene resin (B) is less than 1 part by weight, the fluidity and processability of the composition are deteriorated. When the content exceeds 99 parts by weight, the flexibility of the composition is insufficient, which is not desirable.

The olefin-based thermoplastic elastomer composition of the present invention has a formula (a) between the ratio M (%) of the matrix region and the surface hardness H of the composition: 0.8H-50 ≦ M ≦ 0.
It is desirable that the morphology satisfy 8H-20.

Here, the ratio M of the matrix area is obtained by the following method.

After placing the composition at −60 ° C., a slice is prepared by slicing with a microtome to a thickness of 75 nm. This section is stained with 0.1 g of ruthenium trichloride, added with 5 ml of a sodium hypochlorite solution, and left overnight in the steam generated to stain the section. Then, a 5,000-fold enlarged photograph of the section is taken with a transmission electron microscope. Change location and take 5 pictures. Next, the area ratio between the unstained portion (matrix region) and the stained portion is separated by an image processing device, and the ratio M (%) of the matrix region to the entire screen is measured. The average value of the five photographing locations is defined as the measured value of M.

The surface hardness H is ASTM D224.
It is a measured value of the composition before foaming according to the surface hardness A type defined as 0.

When the composition is within the above range, the composition has an appropriate melt fluidity as a thermoplastic elastomer and also has excellent rubber-like properties such as excellent compression set and rebound resilience. The composition is excellent in balance between moldability and mechanical strength. The control of the ratio M of the matrix area is as follows.
It is carried out by the relative ratio of (A) the ethylene / α-olefin copolymer and (B) the propylene-based resin, the addition ratio of the softener, and the addition ratio of other additional components.

In the present invention, (C) a softening agent can be added to the composition, if necessary, for improving the processability.

The (C) softening agent is preferably a paraffinic or naphthenic process oil. These are used in an amount of 0 to 250 parts by weight, preferably 10 to 150 parts by weight, for adjusting the hardness and flexibility of the composition. If the amount exceeds 250 parts by weight, bleeding of oil tends to be remarkable.

In the present invention, the composition may be added to the specific olefin-based elastomer (A) ethylene / α-olefin copolymer and (B) propylene-based resin, if necessary, with (C) By combining a softener in a specific composition ratio, the balance between mechanical strength, flexibility and workability is improved, and the softener can be preferably used.

The composition provided in the present invention needs to be partially or completely crosslinked with a radical initiator such as an organic peroxide or a radical initiator and a crosslinking aid. This makes it possible to further improve the mechanical strength, heat resistance, oil resistance and the like of the composition.

It is important that the ethylene / α-olefin copolymer (A) has a degree of crosslinking of 50% or more, preferably 60% or more, and more preferably 70% or more.
%, Most preferably at least 80%, very preferably at least 90%. When the degree of crosslinking is less than 50%, mechanical strength such as tensile strength decreases.

The (A) ethylene / α-olefin copolymer must have a swelling degree of 5 to 40%,
Preferably it is 10 to 35%, more preferably 10 to 35%.
It is 30%, most preferably 10-25%, very preferably 10-20%. The degree of swelling is a measure of the crosslink density; conventional olefin-based elastomers have a degree of swelling of 5%.
Although less than or greater than 40%, the inventor has found that only when the degree of swelling is between 5 and 40% has excellent mechanical properties.

Here, specific examples of the radical initiator preferably used include 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane,
1,1-bis (t-hexylperoxy) -3,3,5
-Trimethylcyclohexane, 1,1-bis (t-hexylperoxy) cyclohexane, 1,1-bis (t-
Butylperoxy) cyclododecane, 1,1-bis (t
-Butylperoxy) cyclohexane, 2,2-bis (t-butylperoxy) octane, n-butyl-4,
Peroxy ketals such as 4-bis (t-butylperoxy) butane and n-butyl-4,4-bis (t-butylperoxy) valerate; di-t-butyl peroxide, dicumyl peroxide, t -Butylcumyl peroxide, α, α′-bis (t-butylperoxy-m
-Isopropyl) benzene, α, α'-bis (t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5-bis (t-butylperoxy) hexane and 2,5-dimethyl-2,5 And dialkyl peroxides such as -bis (t-butylperoxy) hexyne-3.

Further, acetyl peroxide, isobutyryl peroxide, octanoyl peroxide, decanoyl peroxide, lauroyl peroxide,
3,5,5-trimethylhexanoyl peroxide,
Diacyl peroxides such as benzoyl peroxide, 2,4-dichlorobenzoyl peroxide and m-trioyl peroxide; t-butyl peroxyacetate, t-butyl peroxyisobutyrate, t
-Butylperoxy-2-ethylhexanoate, t-
Butylperoxylaurate, t-butylperoxybenzoate, di-t-butylperoxyisophthalate, 2,5-dimethyl-2,5-di (benzoylperoxy) hexane, t-butylperoxymaleic acid, t-butylperoxymaleate
Peroxyesters such as -butylperoxyisopropyl carbonate and cumylperoxyoctate.

Further, t-butyl hydroperoxide, cumene hydroperoxide, diisopropylbenzene hydroperoxide, 2,5-dimethylhexane-2,5-dihydroperoxide and 1,
Hydroperoxides such as 1,3,3-tetramethylbutyl peroxide can be exemplified.

Among these compounds, 1,1-bis (t-butylperoxy) -3,3,5-trimethylcyclohexane, di-t-butyl peroxide, dicumyl peroxide, 2,5-dimethyl -2,5-bis (t-butylperoxy) hexane and 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3 are preferred.

These radical initiators are used in an amount of 0.04 parts by weight per 100 parts by weight of the ethylene / α-olefin copolymer (A).
It is used in an amount of 2-3 parts by weight, preferably 0.05-1 part by weight. If the amount is less than 0.02 parts by weight, crosslinking tends to be insufficient, and if it exceeds 3 parts by weight, the physical properties of the composition tend not to be improved.

Further, as a crosslinking assistant, divinylbenzene, triallyl isocyanurate, triallyl cyanurate, diacetone diacrylamide, polyethylene glycol diacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, trimethylolpropane triacrylate , Ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, diethylene glycol dimethacrylate, diisopropenylbenzene, P-quinone dioxime, P, P'-dibenzoylquinone dioxime, phenylmaleimide, allyl methacrylate, N, N'-
m-phenylene bismaleimide, diallyl phthalate,
Tetraallyloxyethane, 1,2-polybutadiene and the like are preferably used. These crosslinking aids may be used in combination of two or more.

These crosslinking aids include (A) ethylene.α
-0.1 to 5 parts by weight, preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the olefin copolymer.
If the amount is less than 0.1 part by weight, crosslinking tends to be insufficient,
If the amount exceeds 5 parts by weight, the physical properties of the composition do not improve and an excessive amount of the crosslinking aid tends to remain.

Further, other resins and elastomers may be added to the composition of the present invention to such an extent that its characteristics are not impaired.

For example, polyamide resin, polyphenylene ether resin, polystyrene resin, polyvinyl chloride resin, polyester resin, polyurethane resin, polyphenylene sulfide resin, polycarbonate resin, polyolefin resin, polymethacrylate resin, polyacetal Ethylene-based resins, polyarylate-based resins, polysulfone-based resins, styrene-butadiene random copolymers, ethylene-vinyl acetate copolymers, etc.
Examples include an ethylene-unsaturated carboxylic acid ester copolymer such as a vinyl ester copolymer and an ethylene-ethyl acrylate copolymer, an ethylene-vinyl alcohol copolymer, polybutadiene, polybutene, and polyisobutene.

More specifically, the polystyrene resin is a rubber-modified styrene resin and / or a non-rubber-modified styrene resin. Particularly, examples of the rubber-modified styrene resin include impact-resistant polystyrene, ABS resin ( Acrylonitrile-butadiene-styrene copolymer), AS
Resin (acrylonitrile-styrene copolymer), AAS
Resin (acrylonitrile-acryl rubber-styrene copolymer), AES resin (acrylonitrile-ethylene propylene rubber-styrene copolymer) and the like.

Here, in order to improve the chemical resistance, oil resistance, heat resistance, etc., particularly, thermoplastic resins of polyamide type, polyester type, polycarbonate type and polyurethane type are preferred.

Further, the composition of the present invention may contain an inorganic filler and a plasticizer to such an extent that its characteristics are not impaired.

Examples of the inorganic filler used here include calcium carbonate, magnesium carbonate, silica, carbon black, glass fiber, titanium oxide, clay, mica, talc, magnesium hydroxide, aluminum hydroxide and the like. As the plasticizer, for example, polyethylene glycol, dioctyl phthalate (DOP)
And the like.

Further, other additives such as a flame retardant,
Organic / inorganic pigments, heat stabilizers, antioxidants, ultraviolet absorbers, light stabilizers, silicone oils, antiblocking agents, foaming agents, antistatic agents, antibacterial agents and the like are also suitably used.

The thermoplastic elastomer composition by dynamic crosslinking in the present invention can be produced by using a melt kneader usually used for producing such a thermoplastic elastomer composition. Specifically, there are a batch-type kneader such as a mixing roll, a Banbury mixer, and a pressure kneader, and a continuous-type kneader such as a single-screw extruder and a twin-screw extruder.

The composition of the present invention includes, as a specific example,
It can be manufactured through the following processing steps.

That is, (A) an ethylene / α-olefin copolymer and (B) a propylene resin are thoroughly mixed,
Put into the hopper of the extruder. The radical initiator and the crosslinking assistant may be added from the beginning together with (A) the ethylene / α-olefin copolymer and (B) the propylene-based resin, or may be added from the middle of the extruder. The oil may be added from the middle of the extruder, or may be added separately at the beginning and during the middle. Part of (A) the ethylene / α-olefin copolymer and (B) the propylene-based resin may be partially added in the middle of the extruder. When heated and melted and kneaded in an extruder, (A) a cross-linking reaction occurs between the ethylene / α-olefin copolymer and a radical initiator and a cross-linking auxiliary, and further, an oil or the like is added and the mixture is melt-kneaded to form a cross-link. After the reaction and kneading and dispersion have been sufficiently performed, the mixture is taken out of the extruder. Pelletized to obtain pellets of the composition of the present invention.

Here, (A) the degree of crosslinking and the degree of swelling of the ethylene / α-olefin copolymer are controlled by a radical initiator,
The reaction is carried out according to the type and amount of the crosslinking aid, the reaction temperature, and the reaction system. Excessive addition of a radical initiator and a crosslinking aid increases the degree of crosslinking, but decreases the degree of swelling and does not satisfy these requirements. Alternatively, excessively active radical initiators, cross-linking aids, or high temperature reaction conditions likewise increase the degree of cross-linking but decrease the degree of swelling and do not satisfy these requirements. Then, a radical initiator and a crosslinking assistant are blended into the (A) ethylene / α-olefin copolymer while a small amount of the (C) softener is absorbed in advance in the (A) ethylene / α-olefin copolymer. Thereby, since the crosslinking reaction proceeds gently, it is possible to increase the degree of crosslinking while suppressing a decrease in the degree of swelling.

For the production of the foam of the present invention, it is possible to employ various molding methods used for producing foams of ordinary thermoplastic resin compositions and thermoplastic elastomer compositions. That is, the present invention can be applied not only to injection molding, extrusion molding, blow molding, blow molding, compression molding, calender molding, powder molding and the like but also to other foam molding methods.
In particular, if multilayer molding is used, it is possible to obtain a molded article composed of a hard unfoamed layer and a flexible foamed layer, and the utility value thereof is great.

As a specific example, in the case of injection molding, the foam of the present invention can be manufactured through the following processing steps.

That is, pellets of the olefin-based thermoplastic elastomer composition and a predetermined amount of a foaming agent are thoroughly blended and then charged into a hopper of an injection molding machine. The foaming agent may be added in the form of a powdered foaming agent raw material in a well-blended state with the thermoplastic elastomer pellets, or may be added as a foaming agent master batch.

As the molding conditions, it is desirable that the stagnation in the cylinder be as short as possible at a high injection speed. The molding machine preferably has a check valve.

In general, the blowing agent is classified into a chemical blowing agent and a physical blowing agent. In the present invention, any of the blowing agents can be used.

Specific examples of the physical foaming agent include air,
There are water, carbon dioxide gas, nitrogen gas, aliphatic hydrocarbons (butane, pentane, hexane, etc.), chlorinated hydrocarbons (dichloroethane, dichloromethane, etc.), and chlorofluorocarbon.

The chemical foaming agent is classified into an organic type and an inorganic type. Specific examples of the organic chemical blowing agent include azodicarbonamide, N, N'-dinitrosopentamethylenetetramine, 4,4'-oxybis (benzenesulfonylhydrazide), benzenesulfonylhydrazide, hydrazodicarbonamide, Barium azodicarboxylate, p-toluenesulfonyl hydrazide, azobisformamide, azobisisobutyronitrile, diazoaminobenzene, and the like. Specific examples of the inorganic chemical blowing agent include sodium hydrogen carbonate, sodium carbonate, ammonium hydrogen carbonate, ammonium carbonate, and the like.

These foaming agents are (A) ethylene • α-
It is used in an amount of 0.1 to 30 parts by weight based on 100 parts by weight of the total amount of the olefin copolymer and the propylene resin (B).

Further, various foaming assistants such as urea, stearic acid, zinc stearate and the like can be used in combination with the above foaming agents.

[0073]

The present invention will be described in more detail with reference to examples and comparative examples, but the present invention is not limited to these examples. In these examples and comparative examples, the test methods used for evaluating various physical properties are as follows.

(1) Degree of crosslinking and degree of swelling 0.5 g of the composition was added to 200 ml of orthodichlorobenzene.
The mixture is allowed to reflux for 20 hours, the solution is filtered through a filter, and the weight (W ₁ ) of the swelling composition is measured. Then
After the swelling composition is vacuum-dried at 100 ° C. to remove the solvent, the weight (W ₂ ) is measured again. The degree of crosslinking and the degree of swelling are calculated by the following equations. That is, the weight of (A) the ethylene / α-olefin copolymer in 0.5 g of the composition is W ₀
Then, the degree of crosslinking (%) = 100 × W ₂ / W ₀ and the degree of swelling (%) = 100 × W ₁ / W ₂ .

(2) Surface Hardness Four sheets of a 2 mm thick sheet of the composition before foaming were stacked on each other,
According to MD2240, evaluation was performed in an A type under an atmosphere of 23 ° C.

(3) Expansion ratio The value obtained by dividing the density of the unfoamed body by the apparent density of the expansion was defined as the expansion ratio.

(4) Tensile breaking strength [MPa] The tensile breaking strength was evaluated at 23 ° C. according to JIS K6251.

(5) Tensile Elongation at Break [%] Evaluated at 23 ° C. according to JIS K6251.

(6) Weather resistance Using a carbon arc type sunshine weather meter (manufactured by Suga Test Instruments), a black panel temperature of 63 ° C., rainfall time of 18 minutes / irradiation time of 120 was applied according to ASTM D1499.
And the tensile elongation retention [%] after continuously exposing the 2 mm thick compression molded sheet for 500 hours.

The following components were used in Examples and Comparative Examples.

(1) Blowing agent (a) Azodicarbonamide powder (referred to as F-1). (B) Sodium bicarbonate powder (referred to as F-2).

(2) Components of the olefin-based thermoplastic elastomer composition (a) Ethylene / α-olefin copolymer a) A copolymer of ethylene and octene-1 (EOR-1)
It was manufactured by a method using a metallocene catalyst described in JP-A-3-1630088. Ethylene of copolymer /
Octene-1 composition ratio; 60/40 (weight ratio), density;
0.857 g / cm ³ , MFR; 1.0 (190 ° C. ×
2.16 kg), Mw / Mn = 2.4, with long chain branching, with DSC melting point peak.

B) Copolymer of ethylene and octene-1 (referred to as EOR-2) This was prepared by a method using a metallocene catalyst described in JP-A-3-16388. Ethylene of copolymer /
Octene-1 composition ratio; 75/25 (weight ratio), density;
0.870 g / cm ³ , MFR; 0.5 (190 ° C. ×
2.16 kg), Mw / Mn = 2.3, has a long chain branch, has a DSC melting point peak.

C) Ethylene-propylene-ethylidene norbornene copolymer (referred to as EPDM) It was produced by a method using a Ziegler catalyst. Propylene content: 28% by weight, iodine value 15, density: 0.8
70 g / cm ³ , MFR; 0.4 (190 ° C. × 2.16
kg), no long-chain branching, no DSC melting point peak.

(B) Propylene resin Polypropylene (referred to as PP) Homo isotactic polypropylene, MFR15
(230 ° C x 2.16 kg).

(C) Softener Paraffin oil (referred to as MO) Diana Process Oil PW-90 (Idemitsu Kosan Co., Ltd.)
Made).

(D) Radical generator (referred to as POX) 2,5-dimethyl-2,5-bis (t-butylperoxy) hexyne-3 (e) Crosslinking aid divinylbenzene (referred to as DVB).

(Examples 1 to 5) As an extruder, a twin screw extruder (40 mmφ, L / D
= 47) was used. As the screw, a double screw having a kneading portion before and after the injection port was used.

EOR / PP / POX / DVB / MO = 1
00/55 or 65 or 85 / 0.5 / 1.0
/ 55 (parts by weight), first, EOR
After pre-blending 100 parts by weight of -1 or EOR-2, 15 parts by weight of MO, 0.5 parts by weight of POX, and 1.0 parts by weight of DVB, the remaining components other than MO and the above blend were mixed. . Next, the mixture is charged from a hopper of a twin-screw extruder (cylinder temperature: 220 ° C.), and subsequently, 40 parts by weight of the remaining MO is injected by a pump from an injection port at the center of the extruder, and melt extrusion is performed. ,
The mixture was pelletized with a pelletizer to prepare an olefin-based thermoplastic elastomer composition.

Then, a blend of pellets of the olefin-based thermoplastic elastomer composition and a predetermined amount of a foaming agent was charged from a hopper of an extruder (25 mmφ). A sheet-shaped foam molded product (width 100 mm, thickness 2 mm) was extruded from a T-die at a cylinder temperature of 210 ° C.

Table 1 shows the evaluation results.

Comparative Example 1 An olefin-based thermoplastic elastomer composition was prepared in the same manner as in Example 2 except that EPDM was used as the ethylene / α-olefin copolymer, to obtain a foam molded article. Table 1 shows the evaluation results.

Comparative Examples 2-3 The composition ratio is the same as that of Example 1 or 2, but the components other than MO are first introduced into the twin-screw extruder without pre-blend, and Inject the entire amount of MO from the inlet at
Melt extrusion was performed to prepare an olefin-based thermoplastic elastomer composition in the same manner as in Example 1 or 2, and a foam molded product was obtained. Table 1 shows the evaluation results.

(Comparative Example 4) An olefin-based thermoplastic elastomer composition was prepared in the same manner as in Example 1 except that the amount of PP added was changed to obtain a foam molded article. Table 1 shows the evaluation results.
Shown in

[0095]

[Table 1]

As is clear from the results shown in Table 1, it is clear that the olefin-based thermoplastic elastomer foam provided by the present invention has excellent mechanical strength and weather resistance. Comparative Example 1 was inferior in weather resistance, and Comparative Examples 2 and 3
Was inferior in mechanical strength as compared with Examples 1 and 2 of the same composition. In Comparative Example 4, the expansion ratio did not increase, and the foaming moldability was poor.

[0097]

The foam comprising the olefin-based thermoplastic elastomer composition of the present invention is flexible, has excellent mechanical properties and weather resistance, and can be effectively used as a substitute material for crosslinked foamed rubber and foamed polyurethane. .

The present invention relates to interior and exterior parts of automobiles such as instrument panels, weather strips, console boxes, ceiling materials, steering wheels, seats, etc., home appliances, weak electric appliance housings, various grips, various key tops, electric wire covering materials, It can be widely used for civil engineering construction materials such as flooring and waterproof sheets, gaskets, cushioning materials, rubber feet, shoe soles, toys, miscellaneous goods, stationery, etc., and plays a large role in the industrial world.

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Claims (3)

[Claims] (A) ethylene and α- having 6 to 12 carbon atoms
1 to 99 parts by weight of an ethylene / α-olefin copolymer produced using a metallocene-based catalyst composed of an olefin and 1 to 99 parts by weight of (B) a propylene-based resin [the total amount of (A) and (B) is 100 Parts by weight), and (A) the degree of crosslinking of the ethylene / α-olefin copolymer is 50% or more,
A foam obtained by foaming a thermoplastic elastomer composition having a degree of swelling of 5 to 40%. 2. The formula (a) between the ratio M (%) of the matrix region and the surface hardness H of the composition: 0.8H-50 ≦ M ≦
2. The foam according to claim 1, wherein the morphology satisfies 0.8H-20. 3. The weight ratio of the α-olefin having 6 to 12 carbon atoms in the ethylene / α-olefin copolymer (A) is 30 to 60% by weight, and (A) ethylene / α
The foam according to claim 1 or 2, wherein the olefin copolymer has a density of 0.80 to 0.86.