CA1317052C - Thermoplastic elastomer compositions - Google Patents

Abstract

ABSTRACT
A thermoplastic elastomer composition prepared by crosslinking a composition comprising the following components (A), (B) and (C) by using a phenolic curing agent:
(A) 30-70 parts by weight of an ethylene/.alpha.-olefin copolymer prepared by copolymerizing ethylene and an .alpha.-olefin having 3 to 12 carbon atoms in the presence of a catalyst comprising a solid component and an organoaluminum compound which solid component contains at least magnesium and titanium, said ethylene/.alpha.-olefin copolymer having the following properties (I) to (IV):
(I) Melt index 0.01-100 g/10 min (II) Density 0.860-0.910 g/cm3 (III) Maximum peak temperature as measured according to a not lower than 100°C
differential scanning calorimetry (DSC) (IV) Insolubles in boiling n-hexane not less than 10 wt.%
(B) 70-30 parts by weight of a propylene polymer;
and (C) 70-150 parts by weight, based on 100 parts by weight of the components (A) and (B), of an ethylene/.alpha.-olefin/
non-conjugated diene copolymer rubber.

Description

`~ 13~7~2 THERMOPJ.~STIC ELASTOMER COMPOSITIONS

BACKG~OUND OF I'HE INVENTION
The presen-t invention relates to a thermoplas-tic elastomer composition and more particularly to a thermo-plastic elastomer composition superior in fluidity,permanent set and ex-ternal appearance of molded articles obtained therefrom.
As thermoplastic polyoleEin elastomers there are known compos.itions comprising crystalline polyolefins such as polyethylene and polypropylene as hard segments and amorphous copolymer rubbers such as e~hylene/propylene copolymer rubber (EPR) and ethylene/propylene/non-conju-gated diene copolymer rubber (EPDM) as soft segments, as well as compositions obtained :by partially crosslinking the above compositions. It is also known to prepare hard and soft segments according to a multi-stage polymeriza-tion process r And by changing the proportions of those segments there are ob-tained various grades of products ranging from one superior in ~lexibility up to one having rigidity.
Products of the flexibile grade are attracting great attention because they can be applied as rubbery materials widely to such uses as automobile parts, hoses, electric wire coating and packing.

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~ 3 ~ 2 In preparing such flexible grade of products i-t is necessary to increase the proportion of a soft segmen-t (e.g. EPR or EPDM) and decrease that of a hard segment ~e.g. polyethylene or polypropylene) in order -to impart rub~ery flexibility thereto.
However, such soft segments as EPR and EPDM are poor in tensile strength and inferior in resistance to heat and oil and also inferior in fluidity. Consequently, flexi~le, thermoplastic elastomer compositions con-taining large amounts of such soft segemnts also have the above-mentioned drawback and cannot be applied to a wide variety of uses. Increasing the hard segment proportion to remedy these problems will result in loss of flexibility, deteri-oration of physical propertles such as permanent set and consequent impairmen-t of the function as a flexible, thermoplastic elastomer.
More, in preparing a product of the flexible grade, it is necessary to carry out polymeriza-tions separately for hard and so~t segments, thus resulting in that not only the polymerization apparatus becomes very complicated in structure but also it is very difficult to control the properties and proportion of each segment in each polymer-ization stage and a de~ective product sometimes occurs at the time of changeover from one to another grade.

1 3 ~ 2 Further, the recover of the resulting polymer is also very difficult because a large amoun-t of a rubbery component is contained therein.
The present inventors proposed a novel thermoplastic elastomer composition to remedy the above problems.
It is, however, not so greatly improved in permanen-t set and flexibility.

SUMMARY OF THE INVENTION

It is an object of the present invention is to over-come the above mentioned problems.
It is another ob~ect of the present invention is to provide a thermoplastic elastomer composition superior in fluidity, permanent set, external appearance of molded articles obtained therefrom, flexibility and heat resist-ance and of which various physical properties are well-balanced.
The present invention resides in a thermoplastic elastomer composition obtained b~ crosslinking a composi-tion comprising the following components (A1, (B) and (C) using a phenolic curing agent:
(A) 30-70 parts by weight of an ethylene/~-olefin copolymer prepared by copolymerizi`ng ethylene and an ~-olefin having 3 to 12 carbon a-toms in the presence of a catalyst comprising a solid component and an organoaluminum A

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~3~7~2 compound which solid component contains a-t least magne-sium and titanium, said ethylene~-olefin copolymer having -the following properties (I) to (IV):
(I) Melt index 0.01-lOOg/10 min (II) Density 0.860-0.910 g/cm3 (III) Maximum peak temperature as measured according to a differen-` tial scanning not lower than 100~C
calorimetry (DSC) (IV) Insolubles in boiling n-hexane not less than 10 wt.%
(B) 70-30 parts by weigh-t of a propylene polymer, and (C) 70-150 parts by weight rbased on 100 parts by weight of the components (A) and (B)~ of an ethylene/~- olefin/
non-conjugated diene copolymer rubber.

DETAILED DESCRIPTION OE~ THE PREFERRED EMBODIMENTS
(1) Ethylenek~-Olefin Copolymer (A) In the ethylene/~-ole-Ein copolymer (A) used in the present invention, the ~--olefin to be copolymerized with ethylene is one having 3 to 12 carbon atoms. Examples are propylene, butene-1, 4-methylpentene-1, hexene-1, octene-1, decene 1 and dodecene-1. Particularly pre-ferred are propylene, butene-1, 4-methylpentene-1 and ~3~7~2 hexene-1 which have 3 to 6 carbon atoms. It is prefer~
able that the ~-ole~in conten-t in the ethylene/~-olefin copolymer be in the range to 5 to 40 mol~.
The ~ollowing ~escription is provided about how to prepare -the ethylene/~-olefin copolymer ~A~ used in the present invention.
The catalyst sys-tem used comprises a solid component and an organoaluminum compound, the solid component containing at least magnesium and titanium. For example~
the solid component is obtained by supporting a titanium compound on an inorganic solid compound containing mag-nesium by a known method. Examples of magnesium-containing inorganic solid compounds include, in addition to metal magnesium, magnesium hydroxide, ma~nesium carbonate, magnesium oxide, magnesium chloride, as well as double sal-ts, double oxides, carbonates, chlorides and hydrox-ides, which contain magnesium atom and a metal selected from silicon, aluminum and calcium Eurther, these inorganic solid compounds after treatmen-t or reaction with oxygen-con-taining compounds, sulfur-containing compounds, aromatic hydrocarbons or halogen-containing substances As examples of the above oxygen-containing compounds are mentioned water and organic oxygen-containing compounds such as alcohols, phenols, ketones, aldehydes, carboxylic acids, esters, polysiloxanes and acid amides, ' . ~. ' . ' ~ ~. ' ' .

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~3~7~2 as well as inorganic oxygen-containing compounds such as metal alkoxides and metal oxychlorides. As examples of -the above sul~ur-containing compounds are mentioned organic sulfur-containing compounds such as thiols, thio-ethers and the like, and inorganic sulfur-con-taining compounds such as sulfur dioxide, sulfur trioxide, sulfuric acid and the like. As examples of -the above aromatic hydrocarbons are mentioned mono- and polycyclic aromatic hydrocarhons such as benzene, toluene, xylene, anthracene and phenanthrene. As examples of the above halogen-con-taining compounds are mentioned chlorine, hydro,gen chloride, metal chlorides and organic halides.
To illus-trate the titanium compound, mention may be made of halides, alkoxyhalides, alkoxides and halogenated oxides, of titanium. Tetravalent and trivalent titanium compounds are pre~erred. As tetravalent titanium com-pounds are preferred those represented by the general formual Ti(OR)nX4 n wherein R is an alkyl, aryl or aralkyl group having 1 to 20 carbon atoms, X is a halogen atom and n is 0 ~ n ~ 4, such as, ~or example, titanium tetra-chloride, ti-tanium tetrabromidel titanium tetraioxide, monomethoxytrichlorotitanium, dimethoxydichloroti-tanium, trimethoxymonochlorititanium, tetramethoxytitanium, monoethoxytrichlorotitanium, diethoxydichlorotitanium, triethoxymonochloro-titanium, tetraethoxytitanium, ,,. .. , :

13~7~2 monoisopropoxytrichloro-titanium, diisopropoxydichloro-titatium, triisopropoxymonochlorotitaniu~, tetra isopropoxytitanium, monobutoxytrichlorotitanium, dibutoxydichlorotitanium, monopentoxytrichloro-titanium, monophenoxytrichlorotitanium, diphenoxydichlorotitanium, triphenoxymonochlorotitanium and tetraphenoxytitanium.
As examples of trivalen-t titanium compounds are mentioned titanium trihalides such as titanium tetrachloride and ti-tanium tetrabromide reduced with hydrogen, aluminum, titanium or an organometallic compound of a Group I-III
metal in the Periodic Table, as well as trivalent titanium compounds obtained by reducing tetravalent alkoxytitanium halides o~ the general formula Ti~OR)mX4 m with an organometallic compound o~ a Group I-III metal in -the Periodic Table in which ~ormula R is an alkyl, aryl or aralkyl group having 1 to 20 carbon atoms, X is a halogen a-tom and m is 0~ m c4.
Tetravalent titanium compounds are particularly preferred.
As pre~erred examples o~ catalyst systems are mentioned combinations o~ organoaluminum compounds with such solid components as MgO-RX-TiCl4 (Japanese Patent Publication No. 3514-1976), Mg-SiCl4-ROH-TiCl4 (Japanese Patent Publication No. 23864/1975), MgCl2-Al(OR)3-TiCl4 (Japanese Patent Publication Nos. 152/1976 and 15111/1977), MgCl2-SiCl4-ROH-TiCl4 ~Japanese Patent Laid Open No.

- ~317~52 1065~1/1974), Mg(OOCR)2-~l(OR)3-TiC14 (Japanese Patent Publication No. 11710/1977, Mg-POC13-TiC14 (~apanese Patent Publication No. 153/1976), MgCl2-AlOCl~TiCl4 (Japanese Patent Publica-tion No. 15316/1979) and MgCl~~~l(R)cX3_n-SitORI)mX4_m-TiC14 (Japanese Patent Laid Open No. 95909/1981), in which formulae R and R' are each an organic radical and X is a halogen atom.
As other examples of catalyst systems are mentioned combinations of organoaluminum compounds wi-th reaction products as solid components obtained by the reaction of organomagnesium compounds such as so-called Grignard compounds with titanium compounds. Examples of organo-magnesium compounds are those of the general formulae RMgX, R2Mg and RMg(OR) wherein R is an organic radical having 1 to 20 carbon atoms and X is a halogen atom, and ether complexes thereof, as well as modified compounds obtained by modifying these organomagnesium compounds with other organometallic compounds such as, for example, organosodium, organolithium, organopotassium, organoboron, organocalcium~and organozinc.
More concrete examples of such catalyst systems are combinations of organoaluminum compounds with such solid components as RMgX-TiC14 (Japanese Patent Publication No. 39470/1975), RMgX-phenol-TiC14 (Japanese Patent Publication No. 12953/1979), RMgX-halogenated phenol-`:

.. '' ```` 13~7~2 TiCl4 (Japanese Patent Publication No. 12954/1979) and RMgX-CO2-TiCl4 (Japanese Patent Laid Open No. 73009/1982).
As still other examples of catalyst systems are mentioned combinations oE organoaluminum compounds with solid products obtained by contacting such inorganic oxides as SiO2 and Al2O3 with the solid component containing at least magnesium and titanium. In addition to SiO2 and Al2O3 there also may be mentioned CaO, B2O3 and SnO2 as examples of inorganic oxides. Double oxides thereof are also employable without any trouble. For contacting these inorganic oxides with the solid compo-nent containing magnesium and titanium, there may be adopted a known method. For example, both may be reacted at a temperature of 20 -to 400C, preferably 50 to 300C, usually for 5 minutes to 20 hours, in the presence or absence of an inert solvent, or both may be subjected to a co-pulverization treatment, or there may be adopted a suitable combination of these methods.
As more concrete examples of such ca~alyst systems r mention may be made of combination of organoaluminum compounds with SiO2-ROH-MgCl2-TiCl4 (Japanese Patent Laid Open No. 47407/1981), SiO2-R-O-R'-MgO-AlCl3-TiCl4 ~Japanese Patent Laid Open No. 187305/198~ and SiO2-MgCl2-Al(OR)3-TiCl4-Si(OR')4 (Japanese Patent Laid Open No. 21405/1983) in which formulae R and R' are each a hydrocarbon radical.

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-"` 131~2 In these catalyst systems -the titanium compounds may be used as adduc-ts with organocarboxylic acid esters, and the magnesium-containing inorganic solid compounds may be used after contact treatment wiht organic carboxylic acid esters. Moreover, the organoaluminum compounds may be used as adducts with organocarboxylic acid esters. Further, the catalyst systems may be pre-pared in the presence of organic carboxylic acid esters.
As organic carboxylic acid esters there may be used various aliphatic, alicyclic and aromatic carboxylic acid esters, preferably aromatic carboxylic acid esters having 7 to 12 carbon atoms. Examples are alkyl esters such as methyl and ethyl of benzoic, anisic and toluic acids.
As preferred examples of the organoaluminum compound to be combined with the solid component are mentioned those represented by the general formulae R3Al, R2AlX, RAlX2 r R2AlOR, RAltOR~X and R3Al~X3 wherein Rs, which may the same or different, are each an alkyl, aryl or aralkyl group having 1 to 20 carbon atoms, such as triethylalumi-num, triisobutylaluminum, trlhexylaluminum, trioctyl-aluminum, diethylaluminum chloride, diethylaluminum ethoxide, ethylaluminum sesquichloride, and mixtures thereof.
The amount o~ the organoaluminum compound used is not specially limited, but usually it is in the range of 0.1 to 1,000 mols per mol of the titanium compound.

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3~7~2 The catalyst sys-tem exemplified above may be contacted with an ~-olefin before it is used in the polymerization reaction. By so doing, a stabler oper-ation is ensured as compared with the case where it ls not so treated.
The polymerization reac-tion is carried out in the same manner as in the conventional olefin polymerization reaction using a Ziegler type catalyst. More particularly, the reaction is performed in a substantially oxygen~ and water-free condition in vapor phase or in the presence of an inert solvent or using monomer per se as solvent.
Olefin polymerizing conditions involve temperatures in the range oE 20 to 300C, preferably 40 to 200Cr and pressure in the range from normal pressure to 70 kg/cm2~G, preferably 2 kg/cm2~G or 60 kg/cm2~G. The molecular weigh-t can be adjusted to some extent by changing poly-merization conditions such as polymerization temperature and catalyst mol ratio, but the addition o~ hydrogen into the polymerization system is more effective for this purpose. Of course, two or more multi-stage polymerization reactions involving different polymerization conditions such as different hydro~en concentrations and different polymerization temperatures can be carried out withou-t any trouble.

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~3~L7~52 ~he melt flow rate MFR, according to JIS K 7210, test condition No. 4 (190C, 2.16 kgf) of the ethylene/-olefin copolymer (A) thus prepared is in the range o~ 0.01 to 100 g/10 min, preferably 0.1 to 50 g/10 min. Its density (accordin~ to JIS K 7112) is in the range of 0.860 to 0.910 g/cm3, preferably 0.870 to 0.905 g/cm3 and more preferably 0.~70 to 0.900 g/cm3. Its maximum peak temper-ature (Tm) measured according to a differential scanning calorimetry (DSC) is not lower than 100C, preferably not lower than 110C. Its insolubles in boiling n-hexane are not less than 10 wt.%, preferably 20-~5 wt~ and more preferably 20-90 wt.%.
If MFR of the ethylene/~-olefin copolymer (A) is less than 0.01 g/10 min, MFR of the thermoplastic elas~
tomer composition will become too low, resulting in deterioration of its Eluidity. And i~ it exceeds lO0 g/lO
min, the tensile strength will be ruduced. A density thereof lower than 0.~60 g/cm3 would result in lowering of tensile strength,surface stickiness of the composition and impairmen-t o~ the appearance. A density of the copolymer exceeding 0.910 g/cm3 is not desirable, because it would cause deterioration of ~lexibility and trans-parency. A maximum pea~ temperature thereof as measured according to DSC of lower than 100C is no-t desirable, either, because it would result in lowering of tensile strength, surface stickiness of the composition and reduced resistance to heat.

' ~ 3 ~ 2 If the proportion of insolubles in boiling n-hexane is smaller than 10 w~.%, the resulting composition will be reduced in tensile strength and become sticky on i-ts surface, and thus such a proportion is undesirable.

(2) Propylene Polymer (B) As examples of -the propylene polymer (B) used in the present invention there are mentioned not only a homopolymer of propylene but also block and random copolymers of propylene and other comonomers. Preferred as the comonomers are ~-olefins having 2 to 8 carbon atoms such as, Eor example, ethylene, butane-l, hexene-l, 4-met~ylpentene-1, and octene-l. Preferably, these comonomers are present in proportions not larger than 30 mol% in the copolymers.
The melt flow rate (MFR, according to JIS K 7210, test condition Mo. 14 ) of the pxopylene polymer may be in the range of 0.1 to 100 g/10 min, preferably 0.1 to 50 9/10 min, more preferably 0.5 to 20 g/10 min. If MFR
is smaller than 0.1 g/10 min, it will be impossible to obtain a resin composition having good fluidity, and i~
MFR exceeds 100 g/10 min, it will result in reduced tensile strength and impact strength.

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(3) Ethylenek~-Olefin/Non-Conjugated Diene Copolymer Rubber (C) In the ethylene/~-olefin/non-conjugated diene copolymer rubber (C), examples of -the ~-olefin are propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1 and octene-1, with propylene being particularly preferred.
Examples of the non-conjugated diene are 1,4-hexadiene, 1,6-octadiene, dicyclopentadiene, vinyl norbornene and ethylidene norbornene, with 1,4-hexadiene and ethylidene norbornene being preferred.
The ethylenek~-olefin/non-conjugated diene copolymer rubber used in the invention has a Mooney viscosity !ML1~4, 100C) of 10 to 95. A Mooney viscosity thereof lower than 10 is not desirable because it would result in reduced tensile strength or stlcky surface of the thermo-plastic elastomer composition. A Mooney viscosity of the copolymer rubber exceeding 95 is also undesirable because it will lead to deterioration in the flow property of the thermoplastic elastomer composition.
:: The iodine value lthe degree of unsaturation) of the ethylene/~-olefin/non-conjugated diene copolymer is preferably in the range of S to 30. If the iodine value is smaller than 5, it would cause reduction of physical properties of the thermoplastic:elastomer composition.

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If it exceeds 30, i-t would cause reduction of resistance to heat aging property.

(4) Composition Ra-tio (Mixing Ratio) The composition ratios of the ethy]ene/~-olefin copolymer (A) rhereinaf-ter referred to as component (A)J
the propylene polymer (B) [hereinafter referred to as componen-t (B)~ and the e-thylene/~-olefin/non-conjugated diene copolymer rubber (C) Lhereinafter referred to as component (C)~ in the thermoplastic elastomer composition of the present invention are 30-70 parts, preferably 40-60 parts, by weight of component (A), 70-30 parts, preferably 60-40 parts, by weigh-t of component (B), and 70-150 parts, preferably 80-120 parts, by weiyht based on 100 parts by weight of components (A) and (B), of compo-nent (C).
If the proportion of component (A) exceeds 70 partsby weight, -the heat resistance and fluidity will be reducedl and if it is smaller t:han 30 parts by weight, the flexlbillty and permanent elongation will be reduced.
If the proportion of component IB) exceeding 70% by weight, the flexibility and permanent elongation will be reduced, and if it is smaller than 30 parts by weight, the heat resistance and fluidity will be reduced.

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Further, if the proportion of componen-t (C) is smaller than 70 parts by weight based on 100 parts by weight of eomponents (A) and (B), the ~lexibility and permanent elongation will be exceeds 150 parts by weight, reduced, and if it -the heat resistance strength will be reduced.
(S) Preparation o~ the Thermoplastic Elastomer Composition E~or preparing the thermoplastic elas-tomer composi-tion of the present invention~ the components (A), (B~ and ~C) may be mixed together in predetermined proportionsfollowed by crosslinking by using a phenolic curing agent.
The mixing and crosslinking may be e~fected by any known method. A typical example is a mechanical melt-kneading me-thod which is carried out under the addition of a phenolic curing agent to the above mixture. According to this known method, the crosslinkiny can be e~fected using any of uni- and biaxial extruders, Bambury's mixer, various kneaders and rolls. The melt-kneading temperature is usually in the range o~ 100 to 250C.
As the phenomic curing agent there may be used resol type phenolic resins which have been conventionally used for curing rubbers such as bu-tyl rubber. As preferred examples are mentioned oligomers (e.g. dimer, trimer, tetramér) of alkyl methylol phenols such as tertiary-~ 13~7~

butyl methylol phenol, ~,~,~ tetramethylbutyl methylol phenol, dodecyl methylol phenol, eicosyl methylol phenol and -the like. The crosslinking may be perormed more efficiently by using a crosslinking accelera-tor together with the phenolic curing agent. Preferred example of the crosslinking accelerator are metal oxides such as zinc oxide, titanium oxide and magnesium oxide, metal chlorides such as stannous chloride and ferric chloride.
The amount o the phenolic curing agent used differs according to the performance required for the thermo-plastic elastomer composition, but is usually in the range of 0.5 -to 10 parts by weight, preferably 1 to 5 parts by weight.
If a conventional organic ~eroxide is used instead o the phenolic curing agent. The objects o the present invention are not attained.
The percent insolubles in boiling xylene ~gel per-centage) which is determined after extracting the thermo-plas-tic elastomer composition of the present invention thus obtained by crosslinking using the phenolic curing agent, with boiling xylene fox 5 hours, is in the range o 3 to 60 wt.~, preferably 10 to 50 wt.~. If the gel percentage is smaller than 3 wt.~, the heat resistance and the oil resistance will become poor, and a gel per-centage exceeding 60 wt.~ will result in reducedfluidity and elongation.

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Be~ore or after crosslinking, or during crosslinkiny (particularly during melt-kneading), there may be added, if necessary, fillers such as carbon black, clay, talc, calcium carbonate, silica, metallic fibers and carbon fibers, as well as additives such as antioxidant, flame retardant and coloring agent, and parafEinic, naphthenic or aromatic mineral oils for assisting the despersion o~
the fillers and enhancing flexibility and elasticity.
Further, various kinds of resins and rubbers may be added, i~ necessary, in amoun-ts not causing a change in performance of the thermoplastic elastomer composition of the present invention; for example, crystalline polyolefins such as high and low density polyethylenes and linear low density polyethylenes, natural and synthetic rubbers, and styrene-based thermoplastic elastomers.
The thermoplastic elastomer composition of the present invention has the Eollowing characteristics.
(a) Superlor in 1uidity, so easy to mold, giving molded produc-ts having good appearance.
(b) Superior in heat and oil resistance.
tc) Small permanent elon~ation makes deformation dif~icult.
(d) Superior in flexibility.
(e) Low dnesity and very light weight.
Since the thermoplastic elastomer composition o~ the present invention has such excellent characteristics, its ~17~!~2 application range is extremely wide. The following are applica-tion examples thereof:
(a) au-tomobile interior sheet, mud guard, lace and cover (b) electric wire coating material (c) components of various electric appliances (d) hose (e) various packing (f) window frame sealing material (g) sound insulating material (h) modifier for various polymers ~The ~ollowing examples are given to further illus-trate the present invention, but the invention is notlimited thereto. In the following working examples and comparative examples, physical proper-ties were measured in the Eollowing manner.
LMeasuremerl-t by DSC~
A hot-pressed 100 ~m thick film as a specimen is hea-ted to 170C and held at this temperature for 15 minutes, followed by cooling to 0C at a rate of 2~5C/
min. Then, from this state the temperature is raised to l70C at a rate oE 10C/min and.measurement is made. The vertex positlon of the maximum peak of peaks appearing during the hea~-up period from 0 to 170C is regarded as the maximum peak temperature (Tm).
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~How to Determine Insolubles in Boiling n-Hexane~
A 200 ,um thick sheet is formed using a hot press from which are then cut out three sheets each 20 mm long by 30 mm wide. Using these sheets, extraction is made in boiling n-hexane for 5 hours by means of a double-tube type Soxhlet extractor. n-Hexane insolubles are taken out and vacuum-dried (50C, 7 hours), then the percen-tage insolubles (C6 insoluble) in boiling n-hexane is calcu-lated in accordance with the following equa-tion:

Insolubles in - 10 boiling n-hexane = Weight of extracted sheet (wt.~) Weight of unextracted sheet x 100 (wt.~) rPreparing Test SheetJ
Each resin composition obtained is placed in a mold 2 mm thick, 150 mm long and 150 mm wide, preheated a-t 210C for 5 minutés, then pressure-molded for 5 minutes at the same temperature and at 150 kgjcm2, and thereafter cooled Eor 10 mlnutes a-t 30C under the pressure of 150 kg/cm2, followed ~y annealing at 50C for 20 hours and allowing to stand at room temperature for 24 hours. Thereafter, physical properties are measured.
CMelt Flow Rate~
~ IS K 7210 test condition No. 14 (230C, 2.16 kgf) is used.

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Moreover, another condition (230C and 21.6 kgf) which is closer to the shear rate in a molding operation is used.
The latter reflec-ts fluidi-ty in practical point of view more preferably.
~ensile Test~
Test piece is prepared using No. 3 dumbbell in accordance with JIS K 6301 and it is measured Eor tensile strength at a pulling rate of 50 mm/min.
fPermanen-t Elongatio~
Test piece is prepared using No. 3 dumbbell in accordance with JIS K 6301. It is held at 100% elongated state for 10 minutes, then contrac-ted suddenly and allowed to stand or 10 minutes to check a percen-tage elongation, from which is determined a permanent elongation.
[Vicat Sof-tening Point~
A 3mm thick specimen is prepared in accordance with the test sheet preparing method and it is used ~or measurement. A heat -transfer medium is heated at a rate of 50C/min while applying a load of 250 g through a needle-like indenter placed perpendicularly to the speci-men in a heating ba-th, and the temperature of the heat transfer medium at the time when the needle-like indenter permeated 1 mm is regarded as a Vicat softening point.

7~2 rHardness.~
Test piece is prepared in accordance with JIS K
6301 and measured for hardness using type A tes-t machine.
[Gel Percentage~
A 200 ~lm thick sheet is prepared using a hot press (at 200C for 5 minutes), from which three 40mm x 20mm shee-ts are cut out. The three shee-ts are each placed in a 120-mesh wire gauz~ bag and extrac-ted in boiling xylene for 5 hours using a double-tube type Soxhlet extractor. Boiling xylene insolubles are taken out and vacuum-dried (80C, 7 hours) to determine the boiling xylene insolubles as a gel percentage.
~xternal Appearance oE Extruded Article~
When MFR is measured at 230C and at 21.6 kgf, the surface condition of an extruded product is observed visually.

~ : very good O : good ~ : slightly bad X : bad Components lA) to (C) used in the following Examples and Comparative Examples are as follows:
~Preparing of Component (A~
An ethylene/butene~1 copolymer (A-1) was prepared by copolymerizing ehtylene and butene-1 in the presence of a catalyst comprising a solid ca-talyst component and ':

' 13~ 7~2 -trie-thylaluminum, the solid catalyst component having been obtained from a substantially anhydrous magnesium chloride, 1,2-dichloroethane and titanium te-trachloride.
The ethylene/bu-tene-1 copolymer (A-1) thus ob-tained was found to have an ethylene con-tent of 88.3 mol%, MER
of 0.9 g/10 min, a density of 0.896 g/cm3, Tm of 119.8C
and a C6 insolubles content of 82 wk.%.
rPreparation of Component (A-2)J
An ethylene/bu-tene-1 copolymer (A-2) was prepared by copolymerizing ethylene and butene-1 in the presence of a catalyst comprising a solid catalyst component and triethylaluminum, the solid catalyst component having been obtained froma substan-tially anhydrous magnesium chloride, anthracene and titanium -tetrachloride.
The ethylene/butene-1 copo:Lymer (A-2) thus obtained was found to have an ethylene content of 85.3 mol%, MFR
of 1.0 g/10 min, a density of 0.890 g/cm3, Tm of 121.6C
and a C6 insolubles content of 58 w-t.%.
~Component (B)~
The characteristics of -two polypropylenes ~Components (B-1) and (B-2)¦ used are as follows:

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EthyTene _ Component Polymerization Content MFR
. . (Mol%) 9/10 min (B - 1) Random copolymeri- 5.9 7 ration with ethylene (B 2) Block copolymeri- 3.3 8 ~ation with ethylene . _ ~Component (C)]
The characteristics of two ethylene/~-olefin/non-conjugated diene copolymer rubbers ~EP 57P and EP 27P
(both are products of Japan Synthetic Rubber Co., Ltd.
and re~erred to as (C - 1) and ~C - 2), respectively~
used are as follows.

Mooney Propylene .
10 Component ViscosityContent Iodlne ML1~4,100C(wt%) a ue (C - 1) 88 28 15 (C - 2) 47 43~ 15 (C - 31 24 26 0 Examples 1 to 5 Componen-ts (A), (B) and (C) in the proportion, stated : ~ in Table l were blended and thereafter a predetermined amount o~ a phenolic curing agent was added and dry-blended.

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~3~7~2 Then the resultant mixture was introduced into a Banbury's mixer prehea-ted to 200C, in which kneading was performed for 20 minutes at 40 rpm t.o obtain a thermoplastic elastomer composition.
The physical properties thereof were measured and are shown in Table 1.

Comparative ~xample 1 The procedure of Example 1 was repeated except that the phenolic curing agent was replaced by 0.5 part by weight of di(tertiary-butyl peroxy)diisopropylbenzene.
Physical properties of the resultant composition was measured, the results of which are as shown in Table 2.

Comparative Example 2 The procedure of ~xample 1 was repeated except that the phenolic curing agent was not added. The results are as shown in Table 2.

Comparative Examples 3 and 4 - Components ~A), (B) and IC) in the proportions stated in Table 2 were blended and thereafter a predetermined amount of a phenolic curing agent was added and dry-blended. Then the resultant mixture was introduced into a Banbury's mixer preheated to 200C, in which kneading wa~ perEormed for 20 minutes a-t 40 rpm to obtain a thermoplastic elastomer composition.

- 13~7~

The results are as shown in Table 2.

Examples 6 to 8 and Comparative Example 5 Composi-tions (A), (B~ and (C) and a phenolic curing agent in the proportions stated in Tables 1 and 2 were dry-blended and then introduced into a Banbury's mixer preheated to 200C, in which kneading was per~ormed ~or S minutes at 40 rpm. Then 5 parts by weight of titanium oxide and 1.5 parts by weight of stannous chloride(bo-th are crosslinking accelerators1 were added and kneading was per~ormed again for 10 minutes to obtain a thermo-plastic elastomer. The results are as shown in Tables 1 and 2~.

Examples 9 and 10 Compositions (~), (B) and ~C) and phenolic curing agent in the proportions stated in Table 1 were blended and th~n 20 parts by weight o~ cIay was added and dry-blended. Then the resultant mixture was introduced into a Banbury's mixer preheated to 200C, in which kneading was performed at 40 rpm for 15 minu-tes while gradually adding 60 parts by weight of a processin~ oil ("KOMOREX
300", a product of Nippon Oil Co., Ltd.) to obtain a thermoplastic elastomer composition. The resul-ts are as shown in Table 1.

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~

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CC O o o N 00 0 O O o o E

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_ .

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Claims (8)

1. A thermoplastic elastomer composition prepared by crosslinking a composition comprising the following components (A), (B) and (C) by using a phenolic curing agent:
(A) 30-70 parts by weight of an ethylene/.alpha.-olefin copolymer prepared by copolymerizing ethylene and an .alpha.-olefin having 3 to 12 carbon atoms in the presence of a catalyst comprising a solid component and an organoaluminum compound which solid component contains at least magnesium and titanium, said ethylene/.alpha.-olefin copolymer having the following properties (I) to (IV):
(I) Melt index 0.01-100 g/10 min (II) Density 0.860-0.910 g/cm3 (III) Maximum peak temperature as measured according to a not lower than 100°C
differential scanning calorimetry (DSC) (IV) Insolubles in boiling n-hexane not less than 10 wt.%
(B) 70-30 parts by weight of a propylene polymer;
and (C) 70-150 parts by weight, based on 100 parts by weight of the component (A) and (B), of an ethylene/.alpha.-olefin/
non-conjugated diene copolymer rubber.

2. A composition as set forth in Claim 1, wherein when the crosslinking is performed a metal compound type crosslinking accelerator is used together with the phenolic curing agent.

3. A composition as set forth in Claim 1, wherein the .alpha.-olefin content of the ethylene/.alpha.-olefin copolymer (A) is in the range of 5 to 40 mol%.

4. A composition as set forth in Claim 1, wherein the .alpha.-olefin of the ethylene/.alpha.-olefin copolymer (A) is propylene, butene-1, 4-methylpentene-1, hexene-1, octene-1, decene-1, or dodecene-1.

5. A composition as set forth in Claim 1, wherein the propylene polymer (B) is a homopolymer of propylene or a copolymer of propylene and an .alpha.-olefin having 2 to 8 carbon atoms.

6. A composition as set forth in Claim 1, wherein the non-conjugated diene of the ethylene/.alpha.-olefin/non-conjugated diene copolymer rubber is 1,4-hexadiene or ethylidene norbornene.

7. A composition as set forth in Claim 1, wherein the ethylene/.alpha.-olefin/non-conjugated diene copolymer rubber (C) has Mooney viscosity (ML1+4, 100°C) in the range of 10 to 95.

8. A composition as set forth in Claim 1, wherein the phenolic curing agent is an alkyl methylol phenol oligomer.