JP2796848B2 - Thermoplastic elastomer - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a thermoplastic elastomer, and more particularly to a thermoplastic elastomer having high strength, excellent fluidity, and excellent flexibility, oil resistance and rubber elasticity.

In recent years, thermoplastic elastomers can use the same processing methods as thermoplastic resins, such as injection molding, hollow molding, rotational molding, and extrusion molding, and have various compositions with appropriate rubber-like flexibility. Products have been put on the market and are used for various purposes because of their high processing efficiency and ease of regeneration as compared with conventional crosslinked rubbers.

Thermoplastic elastomers are soft segments that show rubber-like properties at the operating temperature in the polymer system, and appropriately contain crystals, glass, and other hard segments that are regarded as pseudo-crosslinking points. It is an elastomer molecularly designed to behave in the same manner as described above, and to exhibit the same behavior as a general thermoplastic resin at a processing temperature.

Among various thermoplastic elastomers, polyolefin-based ones are mainly used in the field of automobiles and electric wires because of their outstanding weather resistance and moderate heat resistance.

[Prior Art] An olefin-based thermoplastic elastomer composition comprising a blend of a partially crosslinked monoolefin copolymer rubber and a polyolefin resin is known from JP-B-53-34210. This composition is excellent in flexibility and fluidity, but has a drawback that strength and rubber elasticity are inferior to vulcanized rubber. As an improvement over this drawback, a fully crosslinked ethylene-propylene-non-conjugated diene copolymer rubber (EP
An olefin-based thermoplastic elastomer composition comprising a blend of DM) and a polyolefin resin is also disclosed in JP-B-55-18448.
It is publicly known from Japanese Patent Publication No. However, although this composition has a performance comparable to that of vulcanized rubber, it has a drawback of poor fluidity and has room for improvement.

As described above, the biggest cause of the means for improving one of the drawbacks is that the rubber component used is an amorphous and random copolymer, and furthermore, an unsaturated group is added. This is probably because the EPDM has a narrow molecular weight distribution. Such a copolymer rubber is flexible, but has extremely low strength, and needs to be crosslinked to increase the strength.

However, partial crosslinking with an organic peroxide or the like improves heat resistance, compression set, and the like, but does not significantly improve tensile strength. For this reason, as the amount of the rubber component increases, complete cross-linking is required to maintain the strength, but on the other hand, the fluidity is significantly reduced.

Mineral oil-based softeners are added as a means to improve the decrease in fluidity, but they need to be added in large amounts, such as an increase in kneading time for filling oil, a decrease in strength, bleeding, etc. Will have an undesirable effect.

A crosslinked resin composition using a crystalline ethylene-α-olefin copolymer is disclosed in Japanese Patent Application Laid-Open No. Sho 61-152533, but the crystalline ethylene-α-olefin copolymer used is The molecular weight of the melt index at 190 ° C. is 0.01 to 100 g / 10 min and the molecular weight is relatively small, so the green strength as a soft rubber component is small, and the crosslinking property is inferior for the same reason, as a result, flexibility and strength, rubber It was not enough to obtain a composition with a balanced elasticity.

[Problems to be Solved by the Invention] The present invention relates to a blend of a rubber blended with a polyolefin resin, an ethylene-propylene copolymer rubber having crystallinity and, if necessary, an ethylene-propylene-non-conjugated diene copolymer rubber. By using a material having a specific structure as the ethylene-propylene copolymer rubber, a high fluidity that cannot be achieved by the prior art is maintained, and a strength comparable to a vulcanized rubber can be obtained. An object of the present invention is to provide a thermoplastic elastomer composition having excellent physical properties and excellent flexibility, rubber elasticity and oil resistance.

[Means for Solving the Problems] As a result of intensive studies, the present inventors have found that a high-molecular-weight saturated ethylene-propylene copolymer rubber (EPM) containing polyethylene crystals therein, and ethylene-propylene as needed. According to the present invention, a mixture of a propylene-non-conjugated diene polymer (EPDM), a polyolefin-based resin, and a softening agent, if necessary, are heat-treated dynamically using a curing agent to partially cross-link the rubber component. The present inventors have found that the object of the present invention is achieved, and completed the present invention.

That is, the present invention relates to (a) an ethylene content of 60 to 78 mol%, a crystallinity by X-ray of 4 to 20%, a maximum peak temperature of melting of 100 ° C. or more, and a 230 ° C. melt flow index (MFI). Is less than 0.01, HLMFI / MFI is 35 or more, Mw / Mn is 4 or more, and a tensile breaking strength is 100 kg / cm ³ or more. A mixture of an ethylene-propylene copolymer rubber and an ethylene-propylene non-conjugated diene copolymer rubber. Wherein the content of the ethylene-propylene-non-conjugated diene copolymer rubber in the mixture is 95% by weight or less, 45 to 90 parts by weight of a component comprising the mixture, and (b) a polyolefin resin 10 to A composition consisting of 55 parts by weight was treated with a curing agent and the resulting gel content of component (a) in the crosslinked formulation, determined by immersion in cyclohexane, was 80% by weight at 23 ° C. and 48 hours. Greater than 97% by weight thermoplastic On elastomer.

As the ethylene-propylene copolymer rubber (hereinafter abbreviated as EPM) used as a part of the component (a) of the present invention, one having the following characteristics is used.

That is, the uncrosslinked state has a tensile breaking strength (green strength) [σ] of 100 kg / cm ² or more, preferably 150 kg / cm ² or more, particularly preferably 200 kg / cm ² or more, and an ethylene content of 60 to 78. Mol%, Mw / Mn measured by GPC (gel permeation chromatography) is 4 or more (where Mw and Mn represent weight average molecular weight and number average molecular weight, respectively),
Preferably, it has a high molecular weight of 5 or more and an MFI at 230 ° C. of less than 0.01 and an HLMFI / MFI of 35 or more (however, HLMFI and MFI are JIS K721
0 represents the values of 21.6 kg and 2.16 kg load respectively. ), X
A crystallinity of 4 to 20%, preferably 4 to 10
%, And has a melting peak [Tm] of the polyethylene crystal at 100 ° C. or higher as measured by a differential scanning calorimeter (DSC).

Although the melting point of the crystal component of the above EPM slightly lowers after cross-linking, it acts as a physical cross-linking point, and as long as the crystal component can exist as a crystal (below the melting temperature of the crystal), the cross-linking point linked by a covalent bond Behaves the same as
Apparently, it has the effect of increasing the crosslink density and improves strength and oil resistance.

On the other hand, at a processing temperature of about 160 to 170 ° C or higher, which is higher than the melting temperature of polypropylene, and generally at a temperature of 180 to 230 ° C, the physical crosslinking points disappear due to melting of the polyethylene crystals in the EPM. In order to lower the total crosslink density, the fluidity can be maintained.

Therefore, if the crystallinity of EPM is less than 4%, the strength is reduced due to the lack of physical cross-linking points of the elastomer, and 20%
If it is above, it becomes too hard and the flexibility as the elastomer composition is insufficient.

The ethylene content in the EPM is in the range of 60 to 78 mol%, and if it is less than 60%, the green strength is insufficient, and 78 mol%
If it exceeds, it becomes too hard and lacks flexibility. Shore A substantially corresponds to 50 to 95, and Shore A 60 to 80 is preferable.

The green strength of EPM strongly depends not only on the crystallinity of polyethylene but also on the molecular weight. Green strength of 100 kg / cm ²
In order to achieve the above, the more flexible, that is, the lower the degree of polyethylene crystallinity, the higher the molecular weight, and therefore, the MFI at 230 ° C. must be less than 0.01.

Another effectiveness of reducing the MFI to less than 0.01 is that the gelling efficiency at the time of crosslinking is improved, so that only a small amount of the crosslinking agent in the organic peroxide crosslinking is required, and the entanglement that is advantageous for rubber elasticity is increased, resulting in defects. The number of molecular chain ends can be reduced.

In order to obtain good fluidity, it is essential that the polydispersity value Mw / Mn measured by GPC is 4 or more, preferably 5 or more, and the HLMFI / MFI measured at 230 ° C. is 35 or more. As described above, by widening the molecular weight distribution as compared with the conventional EPM, it is possible to obtain a thermoplastic elastomer composition having excellent fluidity even after crosslinking.

EPM having the above characteristics has excellent performance as a thermoplastic elastomer itself. That is, since the soft segment composed of the ethylene-propylene random copolymer and the hard segment composed of the ethylenic crystal are arranged in the same molecule, it has excellent performance in balance between strength and flexibility.

As a typical method for producing EPM having such performance, an example disclosed in JP-A-57-179207 can be mentioned. According to the method, ethylene and propylene are copolymerized in a slurry state at a reaction temperature of 50 ° C. or less in a saturated or unsaturated hydrocarbon having 4 or less carbon atoms in the presence of a Ziegler-type catalyst, A copolymer rubber suitable for the present invention can be produced. This production method is different from the conventional solution polymerization method by producing in a slurry state, and it becomes possible to easily produce a copolymer rubber containing a high melting point polyethylene crystal component. Further, it becomes easy to increase the molecular weight of the copolymer rubber, which is advantageous for increasing the crosslinkability and strength.

A catalyst system suitable for such a method is disclosed in
No. 34478, No. 51-28189, No. 52-151691, or No. 56-11909, such as titanium, chlorine and optionally magnesium-containing solid components and aluminum trialkyl. A catalyst system containing an organoaluminum compound and, if necessary, a third component;
Nos. 56-151707, 57-141410, 58-45209,
Or a solid component obtained by treating a compound containing at least Ti, Mg, and halogen with a cyclic compound containing chlorine or nitrogen or a compound containing the same and an organoaluminum compound, as proposed in JP-A-59-215304; A catalyst system comprising a cyclic compound containing oxygen and oxygen is preferred.

Preferably, JP-A-56-151707 or 59-215304
No. 59-2153.
This is the catalyst system proposed in No. 04.

However, although the above EPM has excellent performance as a raw material of a thermoplastic elastomer, the rubber component in the composition alone using the above EPM alone has excellent strength and oil resistance, but may lack flexibility. .

In this case, ethylene-propylene-
By blending a non-conjugated diene copolymer rubber (hereinafter abbreviated as EPDM) as a rubber component, a thermoplastic elastomer composition having excellent fluidity and a good balance of strength, oil resistance, flexibility, and rubber elasticity can be obtained. be able to.

Amorphous ethylene-propylene-diene copolymer rubber obtained by a known method can be used as EPDM.

The diene monomer used in EPDM has 5 carbon atoms.
~ 20 non-conjugated dienes such as 1,4-pentadiene, 1,4-
And 1,5-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 -butylidene-2-norbornene, 2-methallyl- and 2-isopropenyl-5-norbornene. Among them, those using ethylidene norbornene or dicyclopentadiene are preferable.

The ratio of ethylene and propylene is such that the ethylene content is 60-78.
The molar percentage of the diene compound is 1 to 15% by weight, preferably 1 to 10% by weight. 135 ° C for Decalin as EPDM
Is 0.5 to 4 dl / g, preferably 1 to 3 dl / g
It is.

The mixing ratio of EPM and EPDM in the rubber component is 95% by weight or less of EPDM, preferably 75/25 to 25/75, more preferably 70% by weight.
/ 30 to 40/60. When the ratio of EPM is large, the strength is high and the fluidity is good, but the hardness is slightly higher. On the other hand, when the ratio of EPDM is high, the permanent elongation becomes small and becomes flexible.

As the polyolefin resin constituting the component (b) of the present invention, a crystalline high-molecular-weight solid product obtained by polymerizing one or more monoolefins by a high-pressure method, a medium-pressure method or a low-pressure method is used. Include. Examples of satisfactory olefins are ethylene, propylene, 1-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.

The polypropylene resin is isotactic homopolypropylene or ethylene, butene-1, hexene-1.
Or a random or block copolymer of α-olefin and propylene, wherein the crystal component is polypropylene or a blend of this with another polyolefin.

The above-mentioned polypropylene resin contributes to the improvement of heat resistance, mechanical strength and fluidity of the thermoplastic elastomer. For this purpose, DSC (Differential Scanning) is used.
Those having a melting point (the maximum peak temperature of melting) of not less than 155 ° C. measured by Galorimetry are preferable. The 230 ° C. melt flow index is 0.01 or more.

The mixing ratio of component (a) and component (b) is
90 parts by weight, 55 to 10 parts by weight of component (b) ((a) + (b) =
If the component (a) is less than 45 parts by weight, the thermoplastic elastomer obtained is too hard and cannot be said to be an elastomer anymore. If it exceeds 90 parts by weight, the strength can be maintained but the fluidity is low. It decreases too much and the moldability deteriorates. When component (a) is 75 parts by weight or more, it is preferable to add a softener in order to improve fluidity.

Also, by using a mixture of homopolypropylene and random polypropylene for the polypropylene resin,
The compatibility between the component (a) and the component (b) is increased, and the breaking strength and the breaking elongation of the thermoplastic elastomer of the present invention can be further increased. The random polypropylene used here is propylene having polypropylene crystals and α-
It is a random copolymer with an olefin. As the α-olefin, ethylene, butene-1, hexene-1 and the like are preferable, and ethylene is particularly preferable. The content of α-olefin is 1 to 15 mol%, the melting point is 120 to 140 ° C., and the MFI is 0.01 or more. The amount of addition is not more than 90% by weight of the highly crystalline polypropylene resin of the component (b). If the content exceeds 90% by weight of the component (b), the heat resistance of the thermoplastic elastomer is impaired, which is not preferred.

The softener is added as necessary to improve the flowability and flexibility of the thermoplastic elastomer of the present invention,
There are paraffin, naphthene, aromatic, polybutene and the like, but for the purpose of the present invention, paraffin, naphthene and polybutene are preferred.

The amount of addition is not more than the equivalent weight of the component (a). Exceeding this amount is not preferred because bleeding of the softener causes surface stickiness and reduction in strength. Further, even if it is not added, the strength and fluidity can be sufficiently maintained up to 75 parts by weight of the copolymer rubber.

The thermoplastic elastomer composition intended in the present invention can be obtained by adding a crosslinking agent in the presence of each of the components (a) and (b) and, if necessary, a softening agent, and dynamically performing a heat treatment.

For example, as shown in JP-B-53-34210, EPR
Is partially crosslinked and blended with a polyolefin resin, a method of crosslinking while mixing a rubber component and a plastic component as disclosed in JP-B-53-21022,
As disclosed in Japanese Patent No. 37953, a technique has been proposed in which a rubber component and a plastic component are sufficiently blended in a kneader in advance, a crosslinking agent is added to such an extent that partial curing is performed, and kneading is continued.

Although any of the above methods can be used to obtain a thermoplastic elastomer having good performance, from the viewpoint of the compatibility between the rubber component and the plastic component, each component excluding the crosslinking agent is sufficiently melt-kneaded in advance. It is preferable to continue the melt-kneading by adding a crosslinking agent. There are various cross-linking agents used in this case, but the obtained elastomer has good properties of compression set, no contamination, good heat resistance, etc. Is desirable.

When each component of (a) and (b) and an organic peroxide are added in the presence of a softening agent as necessary and dynamically heat-treated, the component (b) is not crosslinked by the organic peroxide. Polypropylene resins (which cause molecular cleavage) are preferred. A polyethylene resin crosslinked with an organic peroxide cannot be practically used due to an excessive increase in viscosity. The starting polypropylene used in this case preferably has an MFI of 20 or less.
This is because, during the dynamic treatment, the polypropylene needs to have a certain amount of starting molecular weight to compensate for the decrease in strength due to the gradual reduction of the molecular weight due to molecular cleavage, and to improve the dispersibility of the rubber component. This is to increase the torque of the target processing and the like.

However, since the original rubber component has a large tensile rupture strength, the final polypropylene has an MFI of 100 or more, and in extreme cases, even if the molecular weight is reduced enough to lose ductility, the strength as a composition is still the conventional strength. It is much better than the rubber component, and its fluidity is improved in response to molecular cleavage.

On the other hand, when a curing agent utilizing an unsaturated group such as sulfur vulcanization is used, EPDM is crosslinked, but EPM is not. However, even in this case, high strength can be obtained by using the EPM having the specific structure as described above. However, in this case, since the starting polypropylene does not cause molecular breakage, the MFI of the starting polypropylene should be larger than when using an organic peroxide as a curing agent in order to improve the flowability. preferable. In this case, the MFI is preferably from 10 to 60.

As the organic peroxide used here, for example, dicumyl peroxide, di-tert-butyl peroxide,
2,5-dimethyl-2,5-di- (tert-butylperoxy)
Hexane, 1,3-bis- (tert-butylperoxy-isopropyl) -benzene, tert-butylcumyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) -hexyne, 3,1 1,1-di-tert-butylperoxy-3,3,5-trimethylcyclohexane, tert-butylperoxybenzoate, tert-butylperoxyisopropyl carbonate and the like.

The compounding amount of the organic peroxide is 0.1 to 2 parts by weight, preferably 0.5 to 1.0 part by weight based on 100 parts by weight of (a) and (b) and also the total amount of the softening agent. If the amount is less than 0.05 part by weight, the degree of crosslinking of the component (a) is too small, so that the thermoplastic elastomer of the present invention has insufficient rubber properties such as heat resistance, compression set, and rebound resilience. On the other hand, if the amount exceeds 2 parts by weight, the molecular weight of the component (b) is excessively cut, which causes a decrease in the tensile breaking strength and breaking elongation of the thermoplastic elastomer.

Other suitable crosslinking agents include azide-type crosslinking agents such as formic acid azide and aromatic polyazide; resin vulcanizing agents such as alkylphenol resins and brominated alkylphenol resins; and N, N, N ', N'-tetrabutyl. −, N, N, N ′,
Thiuram disulfides such as N'-tetramethyl- and N, N, N ', N'-tetralauryl-thiuram disulfide, and also p-quinone dioxime and sulfur itself are included. If a sulfur or sulfur donor is used, it is appropriate to use a vulcanization accelerator and an activator such as a metal salt or oxide.

When dynamically heat-treating the organic peroxide, a crosslinking aid can be used. Examples of the crosslinking auxiliary used herein include sulfur, p-quinone dioxime, p, p'-dibenzoylquinone dioxime, ethylene glycol dimethacrylate, 1,3-butylene glycol dimethacrylate, trimethylolpropane trimethacrylate, and trimethylolpropane. Examples include allyl cyanurate, triallyl isocyanurate, diallyl phthalate, polyethylene glycol dimethacrylate, 1,2-polybutadiene, N, N'-m-phenylenebismaleimide, maleic anhydride, and glycidyl methacrylate. The compounding amount is preferably equal to or twice the amount of the organic peroxide.

According to the present invention, the rubber component that crosslinks under dynamic heat treatment conditions remains partially and differs from substantially complete crosslinking.
The effect of crosslinking the rubber component in the composition is, in addition to imparting heat resistance and rubber elasticity, a substantial improvement in tensile strength, but the copolymer rubber used in the present invention is originally high in strength. It is not necessary to increase the crosslink density so as to extremely lower the fluidity, and as a preferable effect of this, particularly in a soft region where the rubber component exceeds 75 parts by weight,
High strength and high fluidity can be achieved.

If the degree of cross-linking of the copolymer rubber is sufficient, that is, if the cross-linking is substantially completely cross-linked, it causes a decrease in fluidity, tends to cause cracks or the like in the molded product, and has a drawback that elongation is reduced. If the degree is below a certain level, tensile strength,
In particular, the effect of improving the tensile strength at high temperatures is not always sufficient.

For the degree of partial crosslinking of the rubber component suitable for the purposes of the present invention, the gel content measured by immersion in cyclohexane at 23 ° C. for 48 hours is more than 80% and less than 97%, preferably more than 90% and less than 97%, more Preferably, it falls within the range of more than 93% and less than 97%.

The EPM used in the present invention already has a gel content of about 70% or more in an uncrosslinked state, and it can be seen that the above object can be achieved with a relatively small amount of organic peroxide.

In order to determine the gel content of the rubber component of the compound crosslinked by the dynamic heat treatment, it is necessary to correct the compound components other than the rubber component. A suitable method for measuring the gel content of the rubber component of the thermoplastic elastomer obtained by the dynamic heat treatment of the composition comprising the rubber component, the resin component, the softener and the crosslinking agent is as follows:
First, the softener and crosslinker residues are removed by Soxhlet boiling point extraction using isopropyl alcohol, and then the residue is removed.
Soak in cyclohexane at 23 ° C for 48 hours to determine soluble matter.
From these, the soluble content based on the resin component is corrected to determine the gel content of the rubber component. The soluble component of the resin component is determined by measuring the resin alone in advance. However, when an organic peroxide is used as a cross-linking agent, the polypropylene-based resin undergoes molecular cleavage and the soluble matter after dynamic heat treatment changes. Is used to cause molecular cleavage, and correction is performed using the relationship between the molecular weight decrease and the soluble component at this time.

In the thermoplastic elastomer of the present invention, talc, carbon black, silica, as long as the performance is not impaired.
Inorganic fillers such as calcium carbonate, barium sulfate, mica and calcium silicate can be blended. Further, if necessary, additives such as stabilizers such as antioxidants and ultraviolet absorbers, lubricants, antistatic agents and flame retardants can be blended.

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

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to Examples.
In addition, the measuring method in an Example is as follows.

(1) MFI: JIS K7210 (load 2.16 kg, 230 ° C) (2) HLMFI: JIS K7210 (load 21.6 kg, 230 ° C) (3) Tensile breaking strength [σ], elongation, permanent elongation: JIS K63
01 (4) Shore A hardness: ASTM D-676-49 (5) Ethylene content in copolymer rubber: by infrared absorption spectroscopy.

(6) [η]: Intrinsic viscosity at 135 ° C of decalin (7) Melting point measurement [Tm]: Measured at a scanning speed of 20 ° C / min using DSC7500 manufactured by PERKIN-ELMER.

-20 ° C to 200 ° C Samples used were pressed sheets which had been melted at 200 ° C and quenched and left for one day or more.

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

(9) Gel fraction: Determined by immersing the sample in cyclohexane at 23 ° C. for 48 hours and determining the amount of insoluble components. At this time, the weight before and after immersion, which is obtained by subtracting the weight of the cyclohexane-soluble component other than rubber, for example, the softener, the plasticizer and the resin component soluble in cyclohexane, from the initial weight is used.

(Manufacture of EPM) Anhydrous magnesium chloride (obtained by drying commercially available anhydrous magnesium chloride in a dry nitrogen stream at about 500 ° C. for 15 hours) 2.1 kg and 0.9 kg of AA type titanium trichloride (Toyo Stofa Co., Ltd.) Co., Ltd.) for 8 hours using a vibrating ball mill to obtain a uniform co-ground product (titanium atom content: 7.2% by weight, chlorine atom content: 73.7% 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)
, And n-hexane of 40 was added thereto, followed by stirring to form a uniform suspension. To this suspension was added 100 g of γ-glycidoxypropyltrimethoxysilane, and the mixture was sufficiently stirred at room temperature for 1 hour. afterwards,
After standing still, the supernatant was removed and 20 toluene was added. Then, 2 kg of tetrahydrofuran was added, and the mixture was sufficiently stirred at room temperature for 2 hours. The treatment system was cooled to room temperature, and the product was sufficiently washed with n-hexane (until no titanium atom was observed in the washing solution) to obtain a solid catalyst component (A).

A 290 tubular loop continuous reactor was filled with liquid propylene, propylene was maintained at 60 kg / H, ethylene was maintained at an ethylene concentration of 10 mol% in the liquid layer, and hydrogen was maintained at a hydrogen concentration of 0.1 in the liquid layer.
Mol%, triethylaluminum (hexane solution) was supplied to this reactor at a rate of 360 mmol / H, tetrahydrofuran at 180 mmol / H, and the fixed catalyst component (A) at a rate of 3.2 g / H. To perform polymerization. The polymer was discharged intermittently in a slurry state to a flash hopper, and the polymer was taken out from the lower portion and dried at 40 ° C. through a warm N2 stream to obtain a polymer powder. These were dry powders without cohesion, and the yield was 16 kg / H. Therefore, the average polymerization activity per solid catalyst was 49.3 kg / g-Ti.

To 100 parts by weight of this powder, 0.05 part by weight of 2,6-di-t-butylparacresol, 0.2 part by weight of dimyristylylthiodipropionate, 0.05 part by weight of tetrakis [methylene-3
-(3 ', 5'-di-tert-butyl-4'-hydroxyphenyl) propionate] methane and 0.2 parts by weight of calcium stearate are added and
It was masticated at 180 ° C. for 5 minutes. The obtained sheet-like sample was compression-molded, and a tensile test and a Shore hardness were measured. It has an ethylene content of 67 mol% and an MFI of 0.007
5, HLMFI 0.3g / 10min, HLMFI / HFI 40, Mw / Mn 5.3, X
The crystallinity of the wire is 7.0%, the melting point of DSC is 110 ° C, and 1 in decalin
The intrinsic viscosity at 35 ° C. was 5.9 dl / g. This sample is designated as EPM-1.

Using the same catalyst and reactor, changing the reaction conditions
EPM-2 to 4 were produced. In addition, the molecular weight distribution (HLMFI / MFI
Commercial EPM-5 was used as an example of a narrow EPM. The properties of these EPMs are shown in Table 1.

On the other hand, EPDM is commercially available Mooney viscosity 65, iodine value
24, which used ethylidene norbornene as the third component. Other properties of this EPDM are also shown in Table 1.

(Manufacture of composition) Toyo Seiki Labo Plastomill, Banbury Mixer 75
Using cc, each component except the crosslinking agent was previously uniformly dispersed at 185 ° C. for 5 minutes at a rotor rotation speed of 60 rpm, then a crosslinking agent and a crosslinking aid were added, and further melt-kneading was continued for 10 minutes. A sample was taken out and hot pressed at 230 ° C. to prepare each test piece.

(Other Raw Materials) In Examples and Comparative Examples, as the polypropylene resin, polypropylene (PP) having an MFI of 0.5 g / 10 min and a melting point of 160 ° C., and an MFI of 0.08 g / 10 min, an ethylene content of 8.8 mol% and a melting point of 130 C. random polypropylene (RPP) was used. Kayahexa AD (manufactured by Kayaku Nouri,
2,5-dimethyl-2,5-di- (t-butylperoxy)-
Hexane), and TAIC (triallyl isocyanurate) was used as a crosslinking aid.

Samper 150 (paraffin oil, manufactured by Sun Oil Co., Ltd.) was used as a softening agent.

(Examples 1 to 4, Comparative Examples 1 to 8) Using the above-mentioned raw materials, various compositions were produced by the above-described method, and the results shown in Table 2 below were obtained.

By blending EPDM with the rubber component as shown in Examples 1 to 4, flexibility is improved and permanent elongation is improved. Further, in Example 1 in which the gel content was increased by increasing the amount of the crosslinking agent added, the breaking strength and the breaking elongation were further improved as compared with Example 4.

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

When no softener is added, the strength is improved but the fluidity is reduced. In Comparative Example 4 in which a softener was added in an amount exceeding the rubber component amount (80 parts), although fluidity and flexibility were improved,
The strength is extremely reduced, and the surface becomes sticky and practicality is lost.

In Comparative Example 1 in which the amount of the crosslinking agent was reduced and the gel content in the rubber component was reduced to 75%, the strength was significantly reduced as compared with Example 2, and the gel content was 99%, that is, the gel was sufficiently crosslinked. In the case of (Comparative Example 3), the fluidity is poor and the elongation is significantly reduced.

In Comparative Example 4 using EPM-3 having a high ethylene content, the composition became hard, the compatibility with PP was poor, and the breaking strength and elongation were not exhibited. When EPM-5 having a small Mw / Mn was used, the fluidity was poor (Comparative Example 6). EPM with large MFI
Comparative Example 7 using EPM-2 and Comparative Example 8 using EPM-2 having a high propylene content and a low breaking strength had significantly lower breaking strengths.

(Example 8) EPM-1 24 parts; EPDM 36 parts; MFI 20 g / 10 minutes, melting point: 160 ° C
40 parts by weight of polypropylene; 100 parts by weight of the above copolymer rubber component, 5 parts by weight of zinc oxide, 1.5 parts by weight of tetramethylkeuram disulfide, mercaptobenzothiazole
0.5 part by weight, 1 part by weight of stearic acid and 1.5 parts by weight of sulfur were mixed, melted and kneaded in the same manner as in the above example, and only the EPDM portion was crosslinked, followed by hot pressing at 230 ° C. to prepare a test piece.

MFI of the composition obtained cannot be measured, HLMFI is 200, tensile broken line strength is 120 kg / cm ² , tensile elongation at break 500%, permanent elongation 25%, Shore A / D: 80/30, elastomer having a gel fraction of 94 was gotten.

[Effects of the Invention] The composition of the present invention comprises an ethylene-propylene copolymer rubber containing a high melting point polyethylene crystal in the rubber component, having a wide molecular weight distribution and a high green strength, and ethylene having excellent flexibility. -By using a blend of a propylene non-conjugated diene copolymer, and by partially cross-linking using an appropriate cross-linking agent, it has higher fluidity and strength than conventionally known thermoplastic elastomers, and flexibility, A thermoplastic elastomer having excellent rubber properties was obtained.

The elastomer of the present invention has excellent balance of flexibility, rubber properties and strength, and has good fluidity, so that it can be used for automobile parts,
For example, bumpers, corner bumpers, side malls,
Suitable for materials such as spirals, weak electric parts, for example, hoses, various packings, insulating sheets, etc., electric cable fields, for example, flexible cords, booster cables, etc., civil engineering and building materials fields, for example, waterproof sheets, waterproof materials, etc.
These parts can be easily formed by ordinary molding methods such as blow molding, extrusion molding, and injection molding.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-58-84838 (JP, A) JP-A-61-247747 (JP, A) JP-A-1-247441 (JP, A) JP-A-1- 197544 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) C08L 23/00-23/36

Claims (4)

(57) [Claims] (1) an ethylene content of 60 to 78% mol;
-Line crystallinity of 4-20%, maximum melting temperature of 100 ℃ or more, 230 ℃ melt flow index (MFI)
Is less than 0.01, HLMFI / MFI is 35 or more, Mw / Mn is 4 or more, and the tensile breaking strength is 100 kg / cm ³ or more, a mixture of an ethylene-propylene copolymer rubber and an ethylene-propylene non-conjugated diene copolymer rubber. The content of the ethylene-propylene-non-conjugated diene copolymer rubber in the mixture is 95% by weight or less, the rubber component of the mixture is 45 to 90 parts by weight, and (b) the polyolefin resin 10 to 10 parts by weight. A composition consisting of 55 parts by weight was treated with a curing agent and the resulting gel content of component (a) in the crosslinked formulation, determined by immersion in cyclohexane, was 80% by weight at 23 ° C. and 48 hours. A thermoplastic elastomer that is greater than 97% by weight. 2. The thermoplastic elastomer according to claim 1, wherein the polyolefin resin (b) is a polypropylene resin. 3. The polypropylene resin of component (b) is composed of 10 to 100% by weight of homopolypropylene and 90 to 0% by weight of a propylene-α-olefin random copolymer containing 5 to 15% by mole of α-olefin. The thermoplastic elastomer according to claim (2). 4. The thermoplastic elastomer according to claim 1, wherein the curing agent is an organic peroxide, and the treatment is made dynamic.