JPH0885741A - Thermoplastic elastomer composition - Google Patents

Abstract

PURPOSE: To obtain a thermoplastic elastomer compsn. which not only has a high flexibility, a high rubber elasticity, and sufficient mechanical strengths but also gives a molding having a good feel to the touch, a low surface luster, and an excellent appearance. CONSTITUTION: This compsn. contains 100 pts.wt. syndiotactic polypropylene, 30--380 pts.wt. cross-linked ethylene-propylene-nonconjugated diene copolymer rubber, and 4-200 pts.wt. polybutene.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoplastic elastomer composition used for obtaining a molded article excellent in flexibility, rubber elasticity, mechanical strength, moldability, appearance and feel.

[0002]

BACKGROUND ART Syndiotactic polypropylene has hitherto been known to be obtained by low-temperature polymerization using a catalyst composed of a vanadium compound, an ether and an organoaluminum. The polymer obtained by this method has a syndiotacticity. It was low and it was hard to say that it represents the original syndiotactic property. On the other hand, J. A. It was discovered by Ewen et al. For the first time that a polypropylene having a high tacticity with a syndiotactic pentad fraction of more than 0.7 can be obtained by a catalyst composed of a transition metal catalyst having an asymmetric ligand and an aluminoxane (J Am. Chem. Soc.,
1988, 110, 6255-6256).

The above J. A. The polymer obtained by the method of Ewen et al. Had a high syndiotacticity and was more elastic than isotactic polypropylene, but it was used as a soft molding material such as soft vinyl chloride or vulcanized rubber. However, its flexibility, rubber elasticity, and mechanical strength were not sufficient when it was applied to the fields in which it is used. In general, attempts have been made to improve the flexibility and impact resistance of polypropylene by blending ethylene-propylene copolymer rubber and the like, but the resin composition obtained by this method has improved flexibility and impact resistance. Although excellent, rubber elasticity and mechanical strength were not sufficient.

[0004]

The object of the present invention is to solve the above problems and to obtain a heat-treated product which is excellent in flexibility, rubber elasticity, mechanical strength, moldability, appearance and feel. It is to provide a plastic elastomer composition.

[0005]

Means for Solving the Problems In view of the above problems, the present inventors have conducted extensive studies and as a result, have found that syndiotactic polypropylene, ethylene-propylene-non-conjugated diene copolymer rubber and polybutene are combined with organic peroxides. It was found that a thermoplastic elastomer composition excellent in flexibility, rubber elasticity, mechanical strength and surface appearance can be obtained by crosslinking while melting and kneading the product or the same with a crosslinking aid in the presence of a crosslinking aid, and completed the present invention. Came to do. That is, the present invention relates to 100 parts by weight of syndiotactic polypropylene (A) and 30 to 380 ethylene-propylene rubber (B).
And a thermoplastic elastomer composition containing 4 to 200 parts by weight of a polybutene resin (C). Hereinafter, the present invention will be described in detail.

The syndiotactic polypropylene used in the present invention may be a homopolymer such as ethylene, 1-butene, 3-methyl-1-butene, 1 as long as it has a substantially syndiotactic structure. -Copolymers containing a small amount of olefins such as hexene, vinylcyclohexene, 1-decene, 1-hexadecene, cyclopentene and norbornene, and dienes such as hexadiene, octadiene, decadiene, dicyclopentadiene and 5-ethylidene-2-norbornene But it doesn't matter. This copolymer can be obtained by copolymerizing propylene and a comonomer in the presence of a known catalyst which gives the poly-α-olefin having good syndiotacticity. The amount of comonomer in the polypropylene is preferably 0 to 20% by weight, particularly preferably 0 to 15% by weight.

The syndiotactic polypropylene used in the present invention has a syndiotactic pentad fraction of 0.5 or more, preferably 0.7 or more, particularly preferably 0.85 or more and less than 0.5. Has poor heat resistance and moldability. Examples of the catalyst for producing syndiotactic polypropylene in the present invention include those disclosed in JP-A-2-41.
No. 303, No. 2-41305, No. 2
-274703, JP-A-2-274704, JP-A-3-179005, and JP-A-3-17900.
Examples of the catalyst include a bridged transition metal compound having mutually asymmetric ligands and a cocatalyst as described in JP-A-6-69394 and JP-A-4-69394, but catalysts having different structures. However, any one can be used as long as it can produce polypropylene having a syndiotactic pentad fraction of 0.5 or more, and as the polymerization method, any of a slurry polymerization method, a bulk polymerization method, and a gas phase polymerization method can be used. .

In the present invention, it is preferable to use ethylene-propylene rubber in order to further improve rubber elasticity such as compression set and permanent elongation of resin, strength and flexibility. The ethylene-propylene rubber is not particularly limited as long as it is a rubber containing ethylene and propylene, but ethylene-propylene copolymer rubber (hereinafter abbreviated as EPR), ethylene-propylene-non-conjugated diene copolymer rubber. (Less than,
Abbreviated as EPDM. ), Or mixtures thereof, are preferred. The same applies when crosslinking is performed, and it is preferable to use ethylene-propylene rubber, and it is preferable to use any of EPR, EPDM, or a mixture thereof, and it is particularly preferable to use EPDM because it is more easily crosslinked.

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. The Mooney viscosity of rubber is 100 ° C, ML _{1 + 4} is 10
120 is desirable, and particularly preferably 20-100. When the Mooney viscosity is less than 10, the mechanical strength is insufficient, and when it exceeds 120, the fluidity is poor and the moldability is poor. The blending amount of the ethylene-propylene rubber is 30 to 380 parts by weight, preferably 80 to 180 parts by weight. If it is less than 30 parts by weight, the rubber elasticity will be insufficient, and if it exceeds 380 parts by weight, the fluidity will be poor and the moldability will be poor.

The polybutene resin used in the present invention is a polymer of butene and includes butene homopolymer and copolymer of butene and α-olefin. The α-olefin copolymerized with butene is not particularly limited, and examples thereof include α-olefins such as ethylene, propylene and hexene, and the content thereof is not particularly limited, but is sufficient as a molded article. Α- to obtain mechanical strength
The olefin-free content is preferably 0 to less than 20 parts by weight, more preferably 0 to less than 10 parts by weight. Polybutene resin has a melt flow index (1
90 ° C., 2.16 kg load, hereinafter MI. ) Is 0.
01-50g / 10min is preferable, 0.05-2
More preferably 0 g / 10 min, 0.1-10
Those having g / 10 min are particularly preferable. This is because if the MI of the polybutene resin is less than 0.01 g / 10 min, the fluidity may be low, which may cause difficulty in compounding, and if the MI exceeds 50 g / 10 min, it will be sufficient as a molded product obtained as a product. This is because a high mechanical strength cannot be obtained. The density is not particularly limited, but in order to obtain sufficient mechanical strength and flexibility as a molded product, 0.81 to 0.95 g / cm ³ , preferably 0.
It may be 89 to 0.92 g / cm ³ . The compounding amount of the polybutene resin is 4 to 200 parts by weight, preferably 20 to 100 parts by weight. If it is less than 4 parts by weight, mechanical elongation and fluidity will be insufficient, and if it exceeds 200 parts by weight, rubber elasticity will be insufficient.

In the present invention, the resin of the present invention may be crosslinked, and an organic peroxide can be used for that purpose. 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) -3,3,5-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-especially in terms of odor and scorch stability.
(T-Butylperoxy) hexane is preferred.

[0012] The addition amount is not particularly limited, but it is 0. 0 with respect to 100 parts by weight of syndiotactic polypropylene.
1 to 3.0 parts by weight is preferable, and 0.2 to 1.0 parts by weight is more preferable. If the addition amount is less than 0.1 part by weight, crosslinking may not be sufficiently performed, so that the composition obtained may be inferior in rubber properties such as strain recovery and impact resilience and mechanical strength. come. If it exceeds 3.0 parts by weight, the molecular weight of the syndiotactic polypropylene may be remarkably reduced, the mechanical strength of the composition may be reduced, or the composition may be excessively crosslinked to reduce the fluidity of the composition. Further, especially when formed into an extruded sheet, the surface thereof may be rough and the appearance and feel may be poor.

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 of the composition will decrease, resulting in poor moldability as well as increasing the amount of unreacted monomer remaining in the composition.

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

When the composition using syndiotactic polypropylene is molded into a sheet or the like in the present invention, the molded product has a more supple and moist feeling than the one using isotactic polypropylene and is excellent in touch. Furthermore, since syndiotactic polypropylene has higher flexibility and lower rigidity than isotactic polypropylene, it is possible to increase the proportion of polypropylene in the composition compared to isotactic polypropylene, so chemical resistance when rubber is compounded. There is little deterioration of the property, and the surface of the molded product is hard to be scratched. Further, since syndiotactic polypropylene is not crosslinked by the organic peroxide, the composition has excellent fluidity.

In the present invention, various softening agents such as process oils can be added for the purpose of improving the flexibility and rubber elasticity of the composition and improving the fluidity during molding. As a method thereof, a method of previously blending with an ethylene-propylene-non-conjugated diene copolymer rubber, a method of blending syndiotactic polypropylene and an ethylene-propylene-non-conjugated diene copolymer rubber, or a method of melt kneading is blended. Either method may be used. The blending amount thereof is 5 to 200 parts by weight, preferably 20 to 150 parts by weight, based on 100 parts by weight of the ethylene-propylene-non-conjugated diene copolymer rubber and / or the ethylene-propylene copolymer rubber (B). . If the compounding amount is less than 5 parts by weight, the softening and plasticizing effects are not sufficient, and if it exceeds 200 parts by weight, not only the mechanical strength of the composition may be significantly lowered, but also when a softening agent is used in a molded article. It is not preferable because it may stick to the surface and make it feel uncomfortable, or it may cause bleed-out or fogging.

The composition of the present invention has flexibility, mechanical strength,
Resins or rubbers other than syndiotactic polypropylene, ethylene-propylene rubber and polybutene resin may be contained within a range that does not significantly deteriorate the moldability, heat resistance, chemical resistance, appearance and feel of the molded product. For example, hydrogen of isotactic homopolypropylene, isotactic ethylene-propylene block copolymer, crystalline isotactic ethylene-propylene random copolymer, ethylene-butene rubber, propylene-butene rubber, styrene-butadiene diblock copolymer. Additive, hydrogenated product of styrene-butadiene-styrene triblock copolymer, hydrogenated product of styrene-isoprene diblock copolymer, hydrogenated product of styrene-isoprene-styrene triblock copolymer, 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. The blending amount is 1 to 50 relative to 100 parts by weight of the composition of the present invention.
Parts by weight are preferred.

Further, fillers such as calcium carbonate, calcium silicate, talc, silica, mica, alumina, barium sulfate, aluminum sulfate, calcium sulfate, graphite, glass fiber are used as long as the fluidity and rubber elasticity of the composition are not impaired. , Glass beads, carbon fiber and the like may be added in an amount of 1 to 50 parts by weight based on 100 parts by weight of the composition of the present invention. If necessary, an antiblocking agent,
Various additives such as 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 composition of the present invention comprises a Banbury mixer,
It can be produced by melt-kneading using a pressure kneader, a twin-screw extruder or the like. For example, when using a twin screw extruder,
A method in which the materials are collectively mixed with a Henschel mixer and then melt-kneaded with an extruder, or materials other than the organic peroxide and the crosslinking aid are melt-kneaded and granulated, and then the organic peroxide and the crosslinking aid are added. Any of the methods of adding and again melt-kneading and granulating can be used. The melting and kneading temperature is preferably 180 to 250 ° C. This pellet can be molded by a usual injection molding method, extrusion molding method, or the like. In particular,
The composition of the present invention has a smaller rubber content than a soft material containing a large amount of rubber, and thus has excellent vacuum / pneumatic moldability.

[0020]

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 Table 1. (1) Tensile breaking strength, elongation, Young's modulus: JIS K63
01 (2) Permanent elongation: A JIS No. 1 dumbbell was stretched 100% and held for 10 minutes, and the residual strain after 10 minutes of load removal was measured.

(3) Gloss: ASTM D-523, measured at an incident angle of 60 ° (4) Hardness: JIS K6301 (5) Tear strength: JIS K6301 (B type dumbbell)

Examples 1 to 4 In accordance with the method described in JP-A-2-275763, a bulk polymerization was carried out in the presence of hydrogen using a catalyst composed of diphenylmethylene (cyclopentadienyl) fluorenyl zirconium dichloride and methylaluminoxane. The intrinsic viscosity (hereinafter abbreviated as [η]) measured in a tetralin solution at 135 ° C. obtained by carrying out is 1.39 dl /
g, melt flow index (hereinafter abbreviated as MFI) is 3.2 g / 10 min, peak temperature of crystallization temperature measured by differential scanning calorimetry is 74.6 ° C., ¹³ C-NM
Syndiotactic homopolypropylene (SPP-1) having a syndiotactic pentad fraction of 0.787 determined by R was added to an ethylene-propylene-non-conjugated diene copolymer rubber according to the composition shown in Table 1 Rubber (manufactured), EP133P), polybutene resin (Shell Japan (manufactured), 8340), 2,5-dimethyl-2,5-di (t-butylperoxy) hexane as a crosslinking agent,
Divinylbenzene as a cross-linking aid and a known stabilizer were blended, melt-kneaded at 200 ° C. in a twin-screw extruder, and then extrusion sheet molded at 210 ° C. to obtain a 0.8 mm-thick sheet. It was

Comparative Example 1 An extruded sheet was obtained in the same manner as in Examples 1 to 4 except that the polybutene resin, organic peroxide and crosslinking aid were not used. The experimental results are shown in Table 2.

Comparative Examples 2 to 3 Extruded sheets having the compositions shown in Table 2 were obtained in the same manner as in Examples 1 to 3. In the case of Comparative Example 2, it contains a large amount of ethylene-propylene-non-conjugated diene copolymer rubber,
That is, since the cross-linking component increased, the moldability was very poor and the appearance was also deteriorated. The experimental results are shown in Table 2.

[0025]

[Table 1]

[0026]

[Table 2]

[0027]

The composition of the present invention is more advantageous than the composition obtained by melt-kneading syndiotactic polypropylene and ethylene-propylene-non-conjugated diene copolymer rubber without using a crosslinking agent and a crosslinking aid. It excels in flexibility and mechanical strength, and especially in rubbery properties such as rubber elasticity such as permanent elongation. Further, as compared with the case of using isotactic polypropylene, it has sufficient flexibility even with a small amount of rubber to be compounded, and is excellent in chemical resistance and scratch resistance. The sheet of this composition has a low surface gloss, is excellent in appearance and feel, and is capable of deep drawing, and thus can be used as a skin material for an automobile interior, for example. Further, since no harmful gas is generated even if it is incinerated after use, it is industrially extremely useful as a substitute for vinyl chloride resin, which is a problem of environmental pollution during combustion.

Claims (4)

[Claims] 1. A thermoplastic elastomer composition containing 100 parts by weight of syndiotactic polypropylene (A), 30 to 380 parts by weight of ethylene-propylene rubber (B), and 4 to 200 parts by weight of polybutene resin (C). 2. Crosslinking 100 parts by weight of syndiotactic polypropylene (A), 30 to 380 parts by weight of ethylene-propylene rubber (B), and 4 to 200 parts by weight of polybutene resin (C) in the presence of an organic peroxide. A composition for a thermoplastic elastomer obtained by 3. The thermoplastic elastomer 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. Composition. 4. 100 parts by weight of syndiotactic polypropylene (A), ethylene-propylene copolymer rubber, ethylene-propylene-non-conjugated diene copolymer rubber, or 30 to 380 parts by weight of a mixture (B) thereof,
And 4 to 200 parts by weight of the polybutene resin (C) are cross-linked in the presence of an organic peroxide, to produce a composition for a thermoplastic elastomer.