JPH02170845A - Thermoplastic elastomer composition - Google Patents

Abstract

PURPOSE:To obtain the subject composition suitable for automobile parts, etc., having high fluidity and excellent strength, flexibility and elastomeric properties by mixing specific rubber component comprising crystalline saturated ethylene- propylene copolymer rubber with specific amount of polyolefinic resin, etc. CONSTITUTION:(A) 45-90 pts.wt. rubber component composed of A1: 5-100wt.% ethylene-propylene copolymer rubber having characteristics such as 60-78mol% ethylene content, 4-20% crystallinity by X-ray and >=100 deg.C melting point and A2: 95-0wt.% ethylene-propylenenon-conjugated diene copolymer rubber and having 80-97% gel content is mixed with (B) 10-55 pts.wt. polyolefinic resin composed of B1: 10-100wt.% homopolypropylene and B2: 90-0-wt.% propylene-alpha- olefin random copolymer and (C) softening agent in an amount of 0-equivalent pts.wt. to (A).

Description

Detailed Description of the Invention (Industrial Field of Application) The present invention relates to a thermoplastic elastomer composition, and particularly to a thermoplastic elastomer composition that has high strength, excellent fluidity, and excellent flexibility and rubber properties. Regarding. In recent years, various thermoplastic elastomers have been developed that can be processed using the same processing methods as thermoplastic resins, such as injection molding, hollow molding, rotary molding, extrusion molding, etc., and have appropriate rubber-like flexibility. The composition is coated and used in a variety of applications due to its superior processing efficiency and ease of recycling compared to conventional crosslinked rubber. Thermoplastic elastomers are made by appropriately arranging soft segments that exhibit rubber-like properties at the operating temperature and hard segments such as crystals, glass, and other pseudo-crosslinking points within the polymer system. It is an elastomer whose molecular design is such that it behaves similar to rubber and behaves similarly to general thermoplastic resins at processing temperatures. Among various thermoplastic elastomers, polyolefin-based ones are mainly used in the automobile field and electric wire field because of their outstanding weather resistance and moderate heat resistance.

[Conventional technology]

An olefinic thermoplastic elastomeric composition comprising a blend of a partially crosslinked monoolefin copolymer rubber and a polyolefin resin is disclosed in Japanese Patent Publication No. 5:1-14210.
It is publicly known from the publication No. This composition has excellent flexibility and fluidity, but has the disadvantage that it is inferior to vulcanized rubber in strength and rubber properties. In order to improve this drawback, an olefinic thermoplastic elastomer composition consisting of a blend of completely crosslinked ethylene-propylene-nonconjugated diene copolymer rubber (EPDM) and a polyolefin resin has been published in Japanese Patent Publication No. 18448/1984, etc. It is known from

Although this composition has performance comparable to that of vulcanized rubber, it has the disadvantage of poor fluidity, and there is room for improvement.

The main reason for the above-mentioned drawbacks is thought to be that the rubber component used is essentially an amorphous and random copolymer and is EPDM containing unsaturated groups. Although such copolymer rubber is flexible, its strength is extremely low, and it is necessary to crosslink it to increase its strength. However, with crosslinking using organic peroxides, heat resistance, compression set, etc. are greatly improved, but tensile strength is not improved that much. Therefore, as the amount of rubber components is increased, it is difficult to maintain strength. In this case, complete crosslinking is required, but on the other hand, fluidity is also significantly reduced. Even if a mineral oil-based softener is added as a means of improving fluidity, it is necessary to use a large amount, which causes undesirable effects such as a decrease in strength and bleeding.

(Problems to be Solved by the Invention) The present invention uses a blend of crystalline saturated ethylene-propylene copolymer rubber and ethylene-propylene-nonconjugated diene copolymer rubber as the rubber to be blended with the polyolefin resin. Furthermore, by using a saturated ethylene-propylene copolymer rubber with a specific structure, it is possible to maintain high fluidity, which was not achieved with conventional technology, and still have tensile strength and flexibility comparable to vulcanized rubber. The purpose of the present invention is to provide a thermoplastic elastomer composition with well-balanced physical properties that are excellent in properties and rubber properties.

(Means for Solving the Problems) As a result of intensive research, the present inventors have discovered that a saturated ethylene-propylene copolymer rubber (EPM) containing polyethylene crystals and an ethylene-propylene non-conjugated diene copolymer Blending a mixture of composite rubber (EPDM), a polyolefin resin, and a softener, and dynamically heat-treating the mixture using a hardening agent to partially crosslink the rubber component, which is a mixture of saturated EPM and EPDM containing diene. The inventors discovered that the object of the present invention can be achieved and completed the present invention.

That is, the gist of the present invention is as follows: (1) (a) Ethylene-propylene copolymer rubber 5-1
[+(1, 1% by weight, 45% to 45% rubber component consisting of 95% to 0% by weight of ethylene-propylene-nonconjugated diene copolymer rubber)
90 parts by weight, (b) 10 to 55 parts by weight of polyolefin resin, (c)
Consisting of a softening agent or equal parts by weight of component (a),
A thermoplastic elastomer composition characterized in that the gel content of component (a) is 80 to 97%.

(2) The thermoplastic elastomer assembly Jm product according to claim (1), wherein the gel content of component (a) is 90 to 97%.

(3) The thermoplastic elastomer set according to claim (1) or (2), wherein the ethylene-propylene copolymer rubber as the component (a) has the following properties.

(i) Ethylene content is 60 to 78 mol%, (b) X-ray crystallinity is 4 to 20%, (c) melting point is 100°C or higher, (d) HLMFI/MFI is 35 or higher, (e) Mw7M
, or more than 4, Kube) Tensile breaking strength or more than 100 kg/crn'.

(4) The thermoplastic elastomer composition according to claim (1), (2) or (3), wherein the polyolefin resin of component (b) is a polypropylene resin.

(5) The polypropylene resin of component (b) is a mixture of 10 to 100% by weight of homopolypropylene and 90 to 0% by weight of a propylene-α-olefin random copolymer having an α-olefin content of 5 to 15 mol%. Certain claim (4)
The thermoplastic elastomer composition described.

Ethylene used as part of component (a) of the present invention
As the propylene copolymer rubber (hereinafter abbreviated as EPM), any known non-grade rubber or one having a small amount of ethylenic crystals can be used.

Among EPMs, those having the following characteristics are preferably used. In other words, the bow breaking strength (
Green strength) is 100 kg/c rn' or more, preferably 150 kg/c rn' or more, particularly preferably 200 kg/c rn' or more, ethylene content is 60 to 78 mol%, and GPC (gel permeation chromatography Mw/M measured in graph) is 4 or more (however,
M, , Mn represent weight average molecular weight and number average molecular weight, respectively), preferably 5 or more, HLMFI/MF at 230 ° C.
I is 35 or more (however, HLMF I, MF 1 is JI
21.6kg and 2.16kg load of S K7210 respectively), crystallinity measured by X-ray is 4-20
%, preferably 4-10% and differential scanning calorimetry (DS
It is preferable that the polyethylene crystal has a melting peak of 100° C. or higher when measured by C).

Even after being crosslinked, the crystalline component of the EPM acts as a physical crosslinking point, and as long as the crystalline component can exist as a crystal (below the melting temperature of the crystal), it behaves in the same way as a crosslinking point connected by covalent bonds, and has an appearance. Additionally, it has the effect of increasing crosslink density, improving strength and oil resistance. on the other hand,
Molding processing temperature (above the melting temperature of polypropylene) of about 160-170℃ or higher, -180-230℃ for boat fishing
At a temperature of , the polyethylene crystals in the EPM melt, thereby eliminating physical crosslinking points and lowering the total crosslinking density, allowing fluidity to be maintained.

As is clear from the above, when the degree of crystallinity is less than 4%, the strength decreases due to the lack of physical crosslinking points, and when it is more than 20%, it becomes too hard and the flexibility as an elastomer composition is insufficient.

Furthermore, the ethylene content in the EPM is preferably 60 to 78 mol%; if it is less than 60%, the green strength will be insufficient;
If it exceeds 78 mol%, it becomes too hard and lacks flexibility. In terms of Shore A, it approximately corresponds to 50 to 95, with Shore A of 60 to 80 being preferred.

The green strength of EPM does not depend on polyethylene crystallinity, but also strongly depends on molecular weight. The softer the material, that is, the lower the crystallinity of the polyethylene, the higher the molecular weight is required in order to increase the green strength to 100 kg/crn' or more.

The molecular weight range of EPM required in the present invention is such that the intrinsic viscosity (η) of decalin at 135° C. is 2.5 to 15 dJl/g, preferably 5 to 10 dJl/g. (
If η) is less than 2.5, the green strength will be insufficient and the crosslinking efficiency will also decrease, which is not preferable; if it is more than 15, the green strength,
Although the crosslinking efficiency is sufficient, the dispersibility and fluidity are poor.

In addition, in order to obtain good fluidity, the polydispersity value Mw/Mn measured by GPC must be 4 or more, preferably 5 or more, and 23
It is essential that the HLMFI/MFI measured at 0°C is 35 or more. By widening the molecular weight distribution compared to conventional EPM, it is possible to obtain a thermoplastic elastomer assembly that still has excellent fluidity even after crosslinking.

EPM having the above characteristics has excellent performance as a raw material for thermoplastic elastomers, but if the rubber component in the composition is the above EPM alone, although it has excellent strength, it may lack flexibility. . In this case, a more flexible thermoplastic elastomer composition can be obtained by blending a flexible ethylene-propylene non-conjugated diene copolymer rubber (hereinafter abbreviated as EPDM) as a rubber component. EPDM is an ethylene-propylene-diene copolymer rubber obtained by a known method, and the diene monomer is a non-conjugated diene having 5 to 20 carbon atoms, such as 1,4-pentadiene, 1,4- and i. , s-hexadiene, 2,5-dimethyl-1,5
-hexadiene and 1,4-octadiene, cyclic dienes such as cyclopentadiene, cyclohexadiene,
cyclooctadiene and dicyclopentadiene, alkenylnorbornenes, such as 5-ethylidene and 5
Examples include those using -butylidene-2-norbornene, 2-methallyl- and 2-isopropenyl-5-norbornene. Among these, those using ethylidene norbornene or dicyclopentadiene are preferred.

Also, the ratio of ethylene to propylene is 60% of ethylene content.
~78 mol%, the diene compound is 1 to 15% by weight of the total,
It is preferably 1 to 10% by weight, and [η] measured at 135°C of decalin is 0.5 to 1Od or/g, preferably 1
~6d sentences/g.

The ratio of EPM and EPDM is 1O
ro/ro to 5/95, preferably 9515 to 30/
70. More preferably, it is 80/20 to 50,150. If the ratio of EPM is high, the strength will be high and the fluidity will be good, but the hardness will be slightly high. On the other hand, when the ratio of EPDM is high, the rubber properties are good and the material is flexible.

The polyolefin resin constituting component (b) of the present invention refers to a crystalline, high-molecular-weight solid product obtained from the polymerization of one or more monoolefins by either a high-pressure method, a medium-pressure method, or a low-pressure method. include. Examples of satisfactory olefins are ethylene, propylene, l-butene,
1-pentene, 1-hexene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, 5-methyl-1-hexene and mixtures thereof. Preferably, it is a polypropylene resin, and the polypropylene resin refers to isotactic homopolypropylene or ethylene, butene-1, hexene-1
It is a random or block copolymer of α-olefin and propylene such as, and the crystal component is polypropylene.

This component contributes to improving the heat resistance 2 mechanical strength and fluidity of thermoplastic elastomers, and for this purpose, the melting point (maximum peak temperature of melting) measured by DSC is
Preferably, at least one is present at a temperature of 155°C or higher. Melt flow index (MF I ) at 230°C
is 0.01 to 100 g/lO min, preferably 0.1 to 2
0g/10 minutes.

The mixing ratio of (a) ti and component (b) is 45 to 90 parts by weight of (a) and 55 to IO parts by weight of component (b) ((
a) + (b) = 100 parts by weight), and if component (a) is less than 45 parts by weight, the thermoplastic elastomer obtained becomes too hard and can no longer be called an elastomer;
If it exceeds 0 parts by weight, the strength can be maintained, but the fluidity will be too low and the moldability will deteriorate. When component (a) is 70 parts by weight or more, it is preferable to add a softener to improve fluidity.

Furthermore, by using a mixture of homopolypropylene and random polypropylene as the polypropylene resin, (a
By increasing the compatibility between component () and component (b), the breaking strength and breaking elongation of the thermoplastic elastomer of the present invention can be further increased. The random polypropylene used here is a random copolymer of propylene and α-olefin having polypropylene crystals, and the α-olefin is preferably ethylene, butene-1, hexene-1, etc., and ethylene is particularly preferred. α-olefin content is 1 to 15 mol%, melting point is 120 to 140°C, 1 MFI is 0
．． O1~100g 710 minutes. The amount added is
9 of the highly crystalline polypropylene resins of component (b)
It is 0% by weight or less. If it exceeds 90% by weight of component (b), the heat resistance of the thermoplastic elastomer will be impaired, which is not preferable.

The softening agent (c) is added to improve the fluidity and flexibility of the thermoplastic elastomer of the present invention, and includes paraffinic, naphthenic, aromatic, and polybutene-based softeners. For the purposes of the invention, paraffinic, naphthenic, and polybutene-based materials are preferred.

The amount added is from zero to less than the equivalent amount of component (a), and if it exceeds this amount, the surface becomes sticky and the strength decreases due to bleeding of the softener, which is not preferable. Moreover, even if the copolymer rubber is not added, strength and fluidity can be maintained sufficiently up to 75 parts by weight or less.

The thermoplastic elastomer composition aimed at in the present invention is (a
), (b), and (c) are obtained by adding a crosslinking agent in the presence of each component and dynamically heat-treating the mixture.

For example, as shown in Japanese Patent Publication No. 53-34210, EPR is partially crosslinked and then blended with a polyolefin resin, and as in Japanese Patent Publication No. 53-21021, a rubber component and a plastic component are mixed and crosslinked. JP-A No. 52-37953 discloses techniques such as a method in which the rubber component and the plastic component are thoroughly blended in advance in a mixing machine, then a crosslinking agent sufficient to partially cure the mixture is added, and the kneading is continued. Proposed. Can a thermoplastic elastomer with good performance be obtained using any of the above methods?From the viewpoint of compatibility between the rubber component and the plastic component, after thoroughly melt-kneading each component except the crosslinking agent, It is preferable to add a cross-linking agent and continue melt-kneading.There are various cross-linking agents that can be used at this time, but the cross-linking agent that can be used is one that provides good compression set and does not cause staining.
Crosslinking using an organic peroxide is desirable because of its good heat resistance. Examples of the organic peroxide used here include dicumyl peroxide, di-tert-butyl peroxide, and 2,5-dimethyl-2,5-di(tert-butyl peroxide).
butylperoxy)hexane, l,3-bis-(ter)
t-butylperoxy-isopropyl)-benzene, t
tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di(tert-butylperoxy)-hexyne, 3.1,1-di-tert-butylperoxy-3,:l,5-trimethylcyclohexane, tert
~Butyl peroxybenzoate, tert-butyl peroxy isopropyl carbonate, etc. may be mentioned.

The blending amount of organic peroxide is (a), (b), (c
) 0.05 to 3 parts by weight, preferably 0.5 to 2.5 parts by weight, based on 100 parts by weight of each component. If the blending amount is less than 0.05 parts by weight, the degree of crosslinking of component (a) will be too small, resulting in the thermoplastic elastomer of the present invention having insufficient rubber properties such as heat resistance and compression set 1 impact resilience. On the other hand, if it exceeds 3 parts by weight, the tensile strength and elongation at break of the thermoplastic elastomer decrease due to excessive molecular cleavage of component (b).

Other suitable crosslinkers include azide-type crosslinkers such as formic azide and aromatic boriacites, as well as N,N
, N', N'-tetrabutyl, N, N, N', N"
-tetramethyl and thiuram disulfides such as N,N,N',N'-tetralaurylthiuram disulfide, and also P-quinonedioxime and sulfur itself. If sulfur or sulfur donors are used, it is appropriate to use promoters and activators 1, such as metal salts or oxides.

A crosslinking aid can be used when dynamically heat treating the organic peroxide. Examples of crosslinking aids used here include sulfur, P-quinonedioxime, P,P'-dibenzoylquinonedioxime, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and trimethylolpropane trimethacrylate. Allyl cyanurate, triallyl isocyanurate,
Diallyl phthalate, polyethylene glycol dimethacrylate, 1,2-polybutadiene, N,N''-
Mention may be made of phenylene bismaleimide, maleic anhydride, and glycidyl methacrylate. The amount to be blended is preferably equal to or twice that of the organic peroxide.

According to the present invention, the rubber component that crosslinks under dynamic heat treatment conditions remains only partially and differs from full, ie, substantially complete, crosslinking. The effect of crosslinking the rubber components in the composition is a substantial improvement in tensile strength;
Since the copolymer rubber used in the present invention has high strength to begin with, it is not necessary to increase the crosslinking density to the extent that fluidity is extremely reduced. If the degree of crosslinking is sufficient, that is, if it is substantially completely crosslinked, it will cause a decrease in fluidity, cracks in the molded product, and a decrease in elongation. Below a certain level, the effect of improving tensile strength, especially tensile strength at high temperatures, is not necessarily sufficient. Rubber components suitable for the purposes of the present invention have a gel content in the range of 80-97%, preferably 90-97%, more preferably 93-97%.

In the thermoplastic elastomer of the present invention, inorganic fillers such as talc, carbon black, silica, calcium carbonate, barium sulfate, mica, and calcium silicate may be blended within a range that does not impair performance. Furthermore, antioxidants, stabilizers such as ultraviolet absorbers, lubricants,
Additives such as antistatic agents and flame retardants can be added.

As the melt-kneading device, conventionally known devices such as an open type mixing roll, a closed type Banbury mixer 1 extruder, and a kneader 5 continuous mixer can be used. Among these, it is preferable to use a closed type apparatus, and it is preferable to knead in an inert gas atmosphere such as nitrogen.

(Example) Hereinafter, the present invention will be explained in more detail with reference to Examples.

Note that the measurement method in the examples is as follows.

(1) MFI: JIS K7210 (Load 2.16kg 230℃) (2) HL MFI
: JIS K7210 (load 21.6kg 2:1
(0℃) (3) Tensile breaking strength, elongation, permanent elongation: JIS 63
01 (4) Shore A hardness: ASTM D-676-49
(5) Ethylene content in copolymer rubber: Based on infrared absorption spectroscopy.

(6) [η]: Intrinsic viscosity of Decalin at 135°C (7) Melting point measurement: Measured at SCAM speed of 20°C/sin using PERKIN-ELMER DSC750 -
200 to 20℃. "C Sample was a pressed sheet that was quenched in a molten state at 200°C and left for one day or more.

(8) Crystallinity: Measured using an X-ray diffractometer manufactured by Rigaku Corporation according to a conventional method.

(9) Gel fraction: The sample was placed in cyclohexane at 23°C.
It is determined by soaking for 8 hours and determining the amount of insoluble components. At this time, the weights before and after dipping are used, which are obtained by subtracting the weights of cyclohexane-soluble components other than rubber, such as two softeners, plasticizers, and cyclohexane-soluble resin components from the initial weight.

(Production of EPM) Anhydrous magnesium chloride (obtained by drying commercially available anhydrous magnesium chloride in a stream of dry nitrogen at about 500° C. for 15 hours) 2.1 kg and 0.5 kg.
9 kg of AA type titanium trichloride (manufactured by Toyo Stofa Co., Ltd.) was co-pulverized in a vibrating ball mill for 8 hours to obtain a homogeneous co-pulverized product (titanium atom content: 7.2% by weight, chlorine atom content: 7%).
3.7% by weight, magnesium atom content 17.7% by weight
, hereinafter referred to as "solid component (F)") was produced.

In this way, 600 g of the solid component (F) was placed in a glass-lined container of 401, and
Hexane was added and stirred to form a homogeneous suspension. 100 g of γ-glycidoxypropyltrimethoxysilane was added to this suspension, and the mixture was stirred at room temperature for 1 hour. Thereafter, the mixture was allowed to stand, the supernatant liquid was removed, and 20 tons of toluene was added. Then, 2 kg of tetrahydrofuran was added and stirred at room temperature for 2 hours. The treatment system was cooled to room temperature, and the product was thoroughly washed with n-hexane (until almost no titanium atoms were observed in the washing solution) to obtain a solid catalyst component (A).

A 290-liter tubular loop continuous reactor was filled with liquid propylene, propylene was kept at 60 kg/H, ethylene was kept at a concentration of 10 mol% in the liquid layer, and hydrogen was kept at a concentration of 0.1 mol% in the liquid layer. , triethylaluminum (
Hexane solution) at 360 mmol/H, tetrahydrofuran at 180 mmol/H1, solid catalyst component (A) at 3.
2 g/H was supplied to this reactor, and polymerization was carried out at a reaction temperature of 30°C. The polymer was intermittently discharged into a flash hopper in the form of a slurry, and the polymer was taken out from the bottom and dried at 40°C through a hot N2 stream to obtain a polymer powder. These are in the form of a smooth powder that does not stick to each other, and the yield is 16 kg.
/H was hot. Therefore, the average polymerization activity per solid catalyst is 4
9.3 kg/g-Ti.

0.05 parts by weight of 2.6 g to 100 parts by weight of this powder
t-Butylpancresol and 0.2 parts by weight of similystyryl thiodipropionate, 0.05 parts by weight of tetrakis(methylene-3-(3°, 5°-di t-butyl-
4°-hydroxyphenyl)propionate)methane and 0.2 parts by weight of calcium stearate,
It was masticated at 180° C. for 5 minutes using a 3-inch roll.

The obtained sheet-like sample was compression molded, and tensile test and Shore hardness were measured. This has an ethylene content of 67 mol% and an HLMFI of 0. :1g/10min,
HLMFI/MFI is 40, M, 7M is 5.4. X
The linear crystallinity was 7.0%, the DSC melting point was 110°C, and the intrinsic viscosity in decalin at 135°C was 5.4 dl/g. This sample will be referred to as EPM-1.

By using the same catalyst and reactor and changing the reaction conditions, various E
PM-2 to PM-5 were manufactured. The properties of these EPMs are the first
As shown in the table.

On the other hand, commercially available EPDM having a Mooney viscosity of 65, an iodine value of 24, and using ethylidene norbornene as the third component was used. Other properties of this EPDM-1 are also shown in Table 1.

(Manufacture of composition) Toyo Seiki Labo Blast Mill, Banbury Mixer 75
Using CC, each component except the crosslinking agent was uniformly dispersed in advance at 185 ° C. for 5 minutes at a rotor rotation speed of 60 rpm, then the crosslinking agent and crosslinking aid were added, and melt-kneading was continued for 10 minutes. Each test piece was prepared by taking a sample and hot pressing it at 230°C.

(Other raw materials) As polypropylene resin, MFI 0.5g/
pp with a melting point of 160°C in 10 minutes and M FI 0.0
8g/lO min, ethylene content 8.8 mol%, melting point 13
Random polypropylene (RPP) at 0°C was used.

As a crosslinking agent, Kayahexa AD (manufactured by Kayaku Nouri Co., Ltd.,
2,5-dimethyl-2,5-di(t-butylperoxy)-hexane), and TAIC was used as the crosslinking aid.
(triallylisocyanurate) was used.

Sambar 150 (manufactured by Sunoil Co., Ltd., paraffin oil) was used as the softener.

(Example 1-io, Comparative Examples 1 to 4) Using the raw materials described above, various compositions were prepared by the method described above. As shown in Examples 1 to 3, by blending EPDM into the rubber component, flexibility is improved and permanent elongation is improved. When the rubber component is EPM only, it either has excellent strength and fluidity, or is slightly inferior in flexibility and rubber properties (permanent elongation).
Example 4).

On the other hand, when the rubber component is only EPDM, the fluidity is extremely reduced and the balance between strength and fluidity is poor (Comparative Example 2).

When no softener was added, the strength improved but the flow decreased. In Comparative Example 4, in which a softener was added in an amount exceeding the amount of the rubber component (80 parts) in the same system, fluidity and flexibility improved but , the strength is extremely reduced and the surface becomes sticky.

In addition, in the case of Comparative Example 1, where the gel content in the rubber component is low at 75%, the strength is significantly reduced compared to Example 2, and when the gel content is 99%, that is, sufficiently crosslinked (Comparative Example 3) It can be seen that the fluidity is poor and the 1 elongation is significantly reduced.

In Example 10 using EPM with high ethylene content, 1
The composition becomes hard, has poor compatibility with PP, and has low breaking strength.
There is no growth. Also M, 7M.

When EPM with a small value is used, the fluidity is poor (Example 8). Furthermore, when the rubber has a small (η), the strength decreases (Example 10).

On the other hand, when homo-PP and random PP are used together (Example 6), the elongation is significantly improved and the strength is also increased.

(Blank below) (Effects of the Invention) The composition of the present invention contains an ethylene-propylene copolymer rubber that contains high melting point polyethylene crystals as a rubber component, has a wide molecular weight distribution, and has high clean strength, and a flexible By using a blend of ethylene-propylene non-conjugated diene copolymer with excellent properties, by partially cross-linking with an appropriate cross-linking agent, it has higher fluidity, higher strength, and flexibility than before. It is possible to obtain a thermoplastic elastomer with excellent rubber properties.

The m-acid of the present invention has an excellent balance of flexibility, rubber properties, and strength, and has good fluidity.
Bumpers, corner bumpers, site moldings, spoilers, etc., light electrical parts, such as hoses, various packings, insulation sheets, etc., electric wire and cable fields, such as flexible cords, booster cables, etc. Civil engineering and building materials fields, such as waterproof sheets, retaining timbers These parts can be easily molded using conventional molding methods such as blow molding, extrusion molding, and injection molding.

Claims (5)

[Claims] (1) (a) Ethylene-propylene copolymer rubber 5-1
00% by weight, 45 to 90 parts by weight of a rubber component consisting of 95 to 0% by weight of ethylene-propylene-nonconjugated diene copolymer rubber, (b) 10 to 55 parts by weight of polyolefin resin, (c)
Consisting of zero or equal parts by weight of component (a), a softening agent;
A thermoplastic elastomer composition characterized in that the gel content of component (a) is 80 to 97%. (2) The thermoplastic elastomer composition according to claim 1, wherein the gel content of component (a) is 90 to 97%. (3) The thermoplastic elastomer composition according to claim (1) or (2), wherein the ethylene-propylene copolymer rubber as component (a) has the following properties. (i) Ethylene content is 60 to 78 mol%, (b) X-ray crystallinity is 4 to 20%, (c) Melting point is 100°C or higher, (d) HLMFI/MFI is 35 or higher, (e) M_w/M_n is 4 or more, (f) Tensile breaking strength is 100 kg/cm^2 or more. (4) The thermoplastic elastomer composition according to claim (1), (2) or (3), wherein the polyolefin resin of component (b) is a polypropylene resin. (5) The polypropylene resin of component (b) is a mixture of 10 to 100% by weight of homopolypropylene and 90 to 0% by weight of a propylene-α-olefin random copolymer having an α-olefin content of 5 to 15 mol%. Certain claim (4)
The thermoplastic elastomer composition described.