Thermoplastic elastomer compositions

A thermoplastic elastomer composition prepared by partially crosslinking a composition comprising the following components (A), (B) and (C): PA1 (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/cm.sup.3 (III) Maximum peak not lower than 100.degree. C. temperature as measured according to a differential scanning calorimetry (DSC) (IV) Insolubles in boiling not less than 10 wt. % n-hexane ______________________________________ PA1 (B) 70-30 parts by weight of a propylene polymer; and PA1 (C) 70-200 parts by weight, based on 100 parts by weight of the components (A) and (B), of an ethylene/.alpha.-olefin copolymer rubber.

BACKGROUND OF THE INVENTION 
The present invention relates to a novel thermoplastic elastomer 
composition comprising partially crosslinked hard and soft segments. More 
particularly, it is concerned with a thermoplastic elastomer composition 
obtained by partially crosslinking a composition of an extremely low 
density ethylene copolymer prepared by copolymerizing ethylene and an 
.alpha.-olefin in the presence of a specific catalyst, a propylene polymer 
and an ethylene/.alpha.-olefin copolymer rubber, the said thermoplastic 
elastomer composition being highly flexible, superior in fluidity and 
resistance to heat and oil, and being small in permanent set. 
As thermoplastic polyolefin elastomers there are known compositions 
comprising crystalline polyolefins such as polyethylene and polypropylene 
as hard segments and amorphous copolymer rubbers such as 
ethylene/propylene copolymer rubber (EPR) and 
ethylene/propylene/non-conjugated 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 polymerization process. And by changing the 
proportions of those segments there are obtained various grades of 
products ranging from one superior in flexibility up to one having 
rigidity. 
Products of the flexible 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. In preparing such 
flexible grade of products it is necessary to increase the proportion of a 
soft segment (e.g. EPR or EPDM) and decrease that of a hard segment (e.g. 
polyethylene or polypropylene) in order to impart rubbery 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, flexible, thermoplastic elastomer compositions containing 
large amounts of such soft segments 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, deterioration of physical properties such as permanent set 
and consequent impairment of the function as a flexible, thermoplastic 
elastomer. 
Moreover, in preparing a product of the flexible grade, it is necessary to 
carry out polymerizations separately for hard and soft 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 polymerization stage and 
a defective product sometimes occurs at the time of changeover from one to 
another grade. Further, the recovery of the resulting polymer is also very 
difficult because a large amount of a rubbery component is contained 
therein. 
Thus, a lot of problems remain to be solved in order to obtain a flexible, 
thermoplastic elastomer of good quality. 
SUMMARY OF THE INVENTION 
It is the object of the present invention to overcome the above-mentioned 
problems of the prior art and provide a process for preparing a highly 
flexible, thermoplastic elastomer composition having superior performance. 
More specifically, the present invention resides in a thermoplastic 
elastomer composition obtained by partially crosslinking a composition 
comprising the following components (A), (B) and (C): 
(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/cm.sup.3 
(III) Maximum peak not lower than 100.degree. C. 
temperature as measured 
according to a 
differential scanning 
calorimetry (DSC) 
(IV) Insolubles in boiling 
not less than 10 wt. % 
n-hexane 
______________________________________ 
(B) 70-30 parts by weight of a propylene polymer, and 
(C) 70-200 parts by weight [based on 100 parts by weight of the components 
(A) and (B)] of an ethylene/.alpha.-olefin copolymer rubber. 
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
(1) Ethylene/.alpha.-Olefin Copolymer (A) 
In the ethylene/.alpha.-olefin copolymer (A) used in the present invention, 
the .alpha.-olefin to be copolymerized with etyylene 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 preferred are 
propylene, butene-1, 4-methyl- pentene-1 and hexene-1 which having 3 to 6 
carbon atoms. Further, dienes such as, for examples, butadiene and 
1,4-hexadiene may be used as comonomers. It is preferable that the 
.alpha.-olefin content in the ethylene/.alpha.-olefin copolymer be in the 
range of 5 to 40 mol %. 
The following description is provided about how to prepare the 
ethylene/.alpha.-olefin copolymer (A) used in the present invention. 
The catalyst system used comprises a solid catalyst component and an 
organoaluminum compound, the solid catalyst component containing at least 
magnesium and titanium. For example, the solid catalyst component is 
obtained by supporting a titanium compound on an inorganic solid compound 
containing magnesium by a known method. Examples of magnesium-containing 
inorganic solid compounds include, in addition to metal magnesium, 
magnesium hydroxide, magnesium carbonate, magnesium oxide, magnesium 
chloride, as well as double salts, double oxides, carbonates, chlorides 
and hydroxides, which contain magnesium atom and a metal selected from 
silicon, aluminum and calcium, further, these inorganic solid compounds 
after treatment or reaction with oxygen-containing compounds, 
sulfur-containing compounds, aromatic hydrocarbons or halogen-containing 
substances. 
As examples of the above oxygen-containing compounds are mentioned organic 
oxygen-containing compounds such as water, alcohols, phenols, ketones, 
aldehydes, carboxylic acids, esters, polysiloxanes and acid amides, as 
well as inorganic oxygen-containing compounds such as metal alkoxides and 
metal oxychlorides. As examples of the above sulfur-containing compounds 
such as thiols, thio-ethers and the like, inorganic sulfur-containing 
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 hydrocarbons such as benzene, toluene, xylene, 
anthracene and phenanthrene. As examples of the above halogen-containing 
compounds are mentioned chlorine, hydrogen chloride, metal chlorides and 
organic halides. 
To illustrate the titanium compound, mention may be made of halides, 
alkoxyhalides, alkoxides and halogenated oxides, of titanium. Tetravalent 
and trivalent titanium compounds are preferred. As tetravalent titanium 
compounds are preferred those represented by the general formula 
Ti(OR).sub.n X.sub.4-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.ltoreq.n.ltoreq.4, 
such as, for example, titanium tetrachloride, titanium tetrabromide, 
titanium tetraiodide, monomethoxytrichlorotitanium, 
dimethoxydichlorotitanium, trimethoxymonochlorotitanium, 
tetramethoxytitanium, monoethoxytrichlorotitanium, 
diethoxydichlorotitanium, triethoxymonochlorotitanium, 
tetraethoxytitanium, monoisopropoxytrichlorotitanium, 
diisopropoxydichlorotitanium, triisopropoxymonochlorotitanium, 
tetraisopropoxytitanium, monobutoxytrichlorotitanium, 
dibutoxydichlorotitanium, monopentoxytrichlorotitanium, 
monophenoxytrichlorotitanium, diphenoxydichlorotitanium, 
triphenoxymonochlorotitanium and tetraphenoxytitanium. As examples of 
trivalent titanium compounds are mentioned titanium trihalides such as 
titanium tetrachloride and titanium tetrabromide 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 of the general formula 
Ti(OR).sub.m X.sub.4-m with an organometallic compound of a Group I-III 
metal in the Periodic Table in which formula R is an alkyl, aryl or 
aralkyl group having 1 to 20 carbon atoms, X is a halogen atom and m is 
0.ltoreq.m.ltoreq.4. Tetravalent titanium compounds are particularly 
preferred. 
As preferred examples of catalyst systems are mentioned combinations of 
organoaluminum compounds with such solid catalyst components as 
MgO-RX-TiCl.sub.4 (Japanese Patent Publication No.3514-1976), 
Mg-SiCl.sub.4 -ROH-TiCl.sub.4 (Japanese Patent Publication No. 
23864/1975), MgCl.sub.2 -Al(OR).sub.3 -TiCl.sub.4 (Japanese Patent 
Publication Nos.152/1976 and 15111/1977), MgCl.sub.2 -SiCl.sub.4 
-ROH-TiCl.sub.4 (Japanese Patent Laid Open No. 106581/1974), 
Mg(OOCR).sub.2 -Al(OR).sub.3 -TiCl.sub.4 (Japanese Patent Publication 
No.11710/1977), Mg-POCl.sub.3 -TiCl.sub.4 (Japanese Patent Publication 
No.153/1976), MgCl.sub.2 -AlOCl-TiCl.sub.4 (Japanese Patent Publication 
No.15316/1979) and MgCl.sub.2 -Al(OR).sub.n X.sub.3-n -Si(OR').sub.m 
X.sub.4-m-TiCl.sub.4 (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 with reaction products as solid catalyst 
components obtained by the reaction of organomagnesium compounds such as 
so-called Grignard compounds with titanium compounds. Examples of 
organomagnesium compounds are those of the general formulae RMgX, R.sub.2 
Mg 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 catalyst components as 
RMgX--TiCl.sub.4 (Japanese Patent Publication No.39470/1975), 
RMgX--phenol-TiCl.sub.4 (Japanese Patent Publication No.12953/1979), 
RMgX--halogenated phenol-TiCl.sub.4 (Japanesse Patent Publication 
No.12954/1979) and RMgX-CO.sub.2 -TiCl.sub.4 (Japanese Patent Laid Open 
No.73009/1982). 
As still other examples of catalyst systems are mentioned combinations of 
organoaluminum compounds with solid products obtained by contacting such 
inorganic oxides as SiO.sub.2 and Al.sub.2 O.sub.3 with the solid catalyst 
component containing at least magnesium and titanium. In addition to 
SiO.sub.2 and Al.sub.2 O.sub.3 there also may be mentioned CaO, B.sub.2 
O.sub.3 and SnO.sub.2 as examples of inorganic oxides. Double oxides 
thereof are also employable without any trouble. For contacting these 
inorganic oxides with the solid catalyst component containing magnesium 
and titanium, there may be adopted a known method. For example, both may 
be reacted at a temperature of 20.degree. to 400.degree. C., preferably 
50.degree. to 300.degree. C., 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 catalyst systems, mention may be made of 
combination of organoaluminum compounds with SiO.sub.2 --ROH--MgCl.sub.2 
--TiCl.sub.4 (Japanese Patent Laid Open No.47407/1981), SiO.sub.2 
--R--O--R'--MgO--AlCl.sub.3 --TiCl.sub.4 (Japanese Patent Laid Open 
No.187305/1982) and SiO.sub.2 --MgCl.sub.2 --Al(OR).sub.3 --TiCl.sub.4 
--Si(OR').sub.4 (Japanese Patent Laid Open No.21405/1983) in which 
formulae R and R' are each a hydrocarbon radical. 
In these catalyst systems the titanium compounds may be used as adducts 
with organocarboxylic acid esters, and the magnesium-containing inorganic 
solid compounds may be used after contact treatment with organic 
carboxylic acid esters. Moreover, the organoaluminum compounds may be used 
as adducts with organocarboxylic acid esters. Further, the catalyst 
systems may be prepared 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 catalyst component are mentioned those represented by the 
general formulae R.sub.3 Al, R.sub.2 AlX, RAlX.sub.2, R.sub.2 AlOR, 
RAl(OR)X and R.sub.3 Al.sub.2 X.sub.3 wherein Rs, which may the same or 
different, are each an alkyl, aryl or aralkyl group having 1 to 20 carbon 
atoms, such as triethylaluminum, triisobutylaluminum, trihexylaluminum, 
trioctylaluminum, diethylaluminum chloride, diethylaluminum ethoxide, 
ethylaluminum sesquichloride, and mixtures thereof. 
The amount of 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. 
The catalyst system exemplified above may be contacted with an 
.alpha.-olefin before its used in the polymerization reaction. By so 
doing, its polymerization activity can be greatly improved and a stabler 
operation is ensured as compared with the case where it is not so treated. 
In this case, various .alpha.-olefins are employable, but preferably those 
having 3 to 12 carbon atoms and more preferably those having 3 to 8 carbon 
atoms. Examples are propylene, butene-1, pentene-1, 4-methylpentene-1, 
hexene-1, octene-1, decene-1, dodecene-1, and mixtures thereof. The 
temperature and time of the contact between the catalyst system and 
.alpha.-olefin can be selected over a wide range, for example, 
0.degree.-200.degree. C., preferably 0.degree.-110.degree. C., and 1 
minute to 24 hours. The amount of the .alpha.-olefin to be contacted with 
the catalyst system can also be selected over a wide range, but usually it 
is desirable that the catalyst system be treated with 1 g to 50,000 g, 
preferably 5 g to 30,000 g, per gram of the solid catalyst component of 
the .alpha.-olefin and reacted with 1 g to 500 g per gram of the solid 
catalyst component of the .alpha.-olefin. The pressure in the contact 
treatment is not specially limited, but preferably it is in the range of 
-1 to 100 kg/cm.sup.2.G. 
In the .alpha.-olefin treatment, the catalyst system may be contacted with 
the .alpha.-olefin after combining the total amount of the organoaluminum 
compound used with the solid catalyst component, or the catalyst system 
may be contacted with the .alpha.-olefin after combining a part of the 
organoaluminum compound used with the solid catalyst component and the 
remaining portion of the organoaluminum compound may be added separately 
in the polymerization reaction. The contact treatment of the catalyst 
system with the .alpha.-olefin may be conducted in the presence of 
hydrogen gas or any other inert gas, e.g. nitrogen, argon or helium. 
The polymerization reaction 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 of 20.degree. to 300.degree. C., 
preferably 40.degree. to 200.degree. C., and pressures in the range from 
normal pressure to 70 kg/cm.sup.2.G, preferably 2 kg/cm.sup.2.G or 60 
kg/cm.sup.2.G. The molecular weight can be adjusted to some extent by 
changing polymerization conditions such as polymerization temperature and 
catalyst mol ratio, but the addition of 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 hydrogen concentrations and different 
polymerization temperatures can be carried out without any trouble. 
The melt index (MI, according to JIS K 6760) of the ethylene/.alpha.-olefin 
copolymer (A) thus prepared is in the range of 0.01 to 100 g/10 min, 
preferably 0.1 to 50 g/10 min. Its density (according to JIS K 6760) is in 
the range of 0.860 to 0.910 g/cm.sup.3, preferably 0.870 to 0.905 
g/cm.sup.3 and more preferably 0.870 to 0.900 g/cm.sup.3. Its maximum peak 
temperature (Tm) measured according to a differential scanning calorimetry 
(DSC) is not lower than 100.degree. C., preferably not lower than 
110.degree. C. Its insolubles in boiling n-hexane are not less than 10 wt. 
%, preferably 20-95 wt. % and more preferably 20-90 wt. %. 
If the melt index of the ethylene/.alpha.-olefin copolymer (A) is less than 
0.01 g/10 min, the melt index of the thermoplastic elastomer composition 
will become too low, resulting in deterioration of its fluidity. And if it 
exceeds 100 g/10 min, the tensile strength will be reduced. A density 
thereof lower than 0.860 g/cm.sup.3 would result in lowering of tensile 
strength, surface stickiness of the composition and impairment of the 
appearance. A density of the copolymer exceeding 0.910 g/cm.sup.3 is not 
desirable, because it would cause deterioration of flexibility and 
transparency. A maximum peak temperature thereof as measured according to 
DSC of lower than 100.degree. C. is not desirable, either, because it 
would result in lowering of tensile strength, surface stickiness of the 
composition and reduced resistance to heat and oil. If the proportion of 
insolubles in boiling n-hexane is smaller than 10 wt. %, the resulting 
composition will be reduced in tensile strength and become sticky on its 
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 .alpha.-olefins having 2 to 8 carbon atoms such as, for 
example, ethylene, butene-1, hexene-1, 4-methylpentene-1, and octene-1. 
Preferably, these comonomers are present in proportions not larger than 30 
mol % in the copolymers. 
The melt flow rate (MFR, according to JIS K 6758) of the propylene polymer 
is in the range of 0.1 to 50 g/10 min, 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 if MFR exceeds 50 g/10 min, it will 
result in reduced tensile strength and impact strength. 
(3) Ethylene/.alpha.-Olefin Copolymer Rubber (C) 
The ethylene/.alpha.-olefin copolymer rubber (C), which is still another 
component used in the present invention, is an ethylene/.alpha.-olefin 
copolymer rubber or an ethylene/.alpha.-olefin/non-conjugated diene 
copolymer rubber. These are amorphous copolymer. 
In the ethylene/.alpha.-olefin copolymer rubber (C), examples of the 
.alpha.-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 ethylene/.alpha.-olefin copolymer rubber used in the invention has a 
Mooney viscosity (ML.sub.1+4, 100.degree. C.) of 10 to 95. A Mooney 
viscosity thereof lower than 10 is not desirable because it would result 
in reduced tensile strength or sticky surface of the thermoplastic 
elastomer compostion. A Mooney viscosity of the copolymer rubber exceeding 
95 is also undesirable because it will lead to deterioration in flowing 
property of the thermoplastic elastomer composition. 
The ethylene/.alpha.-olefin copolymer (A) and the ethylene/.alpha.-olefin 
copolymer rubber (C), which are components of the thermoplastic elastomer 
composition of the present invention, are easily distinguishable from each 
other. Even if both are the same in point of the constituent monomers and 
density, the maximum peak temperature (Tm) is much higher in the component 
(A), while in the case of component (C), even if there is a maximum peak 
temperature (Tm) thereof, it is in the range of 30.degree. to 50.degree. 
C. at most. Also as to insolubles in boiling n-hexane, the component (C) 
does not contain such insolubles, or even if it contains such insolubles, 
the amount thereof is extremely small. The two components are also 
greatly, different in point of how to prepare them. The component (A) is 
prepared using a catalyst which contains magnesium and titanium as 
previously noted, while the component (C) is usually prepared using a 
vanadium catalyst. 
(4) Composition Ratio (Mixing Ratio) 
The composition ratios of the ethylene/.alpha.-olefin copolymer (A) 
[hereinafter referred to as component (A)], the propylene polymer (B) 
[hereinafter referred to as component (B)] and the ethylene/.alpha.-olefin 
copolymer rubber (C) [hereinafter 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 weight of component (B), and 70-200 parts, 
preferably 100-150 parts, by weight based on 100 parts by weight of 
components (A) and (B), of component (C). 
If the proportion of component (A) exceeds 70 parts by weight, the heat 
resistance and fluidity will be deteriorated, and if it is smaller than 30 
parts by weight, deficiency will result in point of flexibility. Thus, 
both such values are undesirable. A proportion of component (B) exceeding 
70 parts by weight will bring about improvement of heat resistance, but 
result in poor flexibility, and if the proportion thereof is smaller than 
30 parts by weight, the heat resistance of the composition will be 
deteriorated. 
Further, if the proportion of component (C) is smaller than 70 parts by 
weight based on 100 parts by weight of components (A) and (B), deficiency 
will result in point of flexibility, and a proportion thereof exceeding 
200 parts by weight will result in lowering of heat resistance and 
strength. 
(5) Preparation of the Thermoplastic Elastomer Composition 
For preparing the thermoplastic elastomer composition of the present 
invention, the components (A), (B) and (C) may be mixed together in 
predetermined proportions followed by partial crosslinking. But, 
preferably, the components (B) and (C) are first mixed together and 
partially crosslinked, thereafter the component (A) is incorporated in the 
mixture. 
The partial crosslinking may be effected by any known method. A typical 
example is a mechanical melt-kneading method which is carried out under 
the addition of a crosslinking agent to the above mixture. According to 
this known method, the partial crosslinking can be effected using any of 
uni- and biaxial extruders, Bumbury's mixer, various kneaders and rolls. 
The melt-kneading temperature is generally not higher than 300.degree. C. 
and preferably it is a temperature at which the half-value period of the 
crosslinking agent used is not longer than one minute, usually in the 
range of 100.degree. to 300.degree. C. The partial crosslinking may be 
performed using heat or radiation after incorporating the crosslinking 
agent in the mixture by impregnation or any other suitable means. 
As the crosslinking agent, an organic peroxide is usually employed. 
Examples are 2,5-dimethyl-2,5-di(t-butylperoxy)hexane, di-t-butyl 
peroxide, di(t-butylperoxy)diisopropylbenzene, 
di(t-butylperoxy)-diisobutylbenzene, dicumyl peroxide, t-butylcumyl 
peroxide, t-butylperoxy benzoate, 1,1-bis(t-butylperoxy)-3,3,5-trimethyl 
peroxide, benzoyl peroxide, and p-chlorobenzoyl peroxide. 
There may be used a crosslinking aid together with the crosslinking agent. 
Examples are liquid polybutadiene, divnylbenzene, ethylene dimethacrylate, 
and diallyl phthalate. 
The amount of the crosslinking agent used is in the range of 0.005 to 3 wt. 
%, preferably 0.05 to 1.0 wt. %, provided this range does not always 
constitute a limitation because the amount of the crosslinking agent to be 
used is determined according to the performance required for the 
crosslinked composition. Several kinds of crosslinking agents and 
crosslinking aids may be used together according to purposes. 
The percent insolubles in boiling xylene (gel percentage) which is 
determined after extracting the thermoplastic elastomer composition of the 
present invention thus obtained by partial crosslinking, with boiling 
xylene for 5 hours, is in the range of 0.5 to 60 wt. %, preferably 2 to 50 
wt. %. If the gel percentage is smaller than 0.5 wt. %, the heat 
resistance and the oil resistance will become poor, and a gel percentage 
exceeding 60 wt. % will result in reduced fluidity and elongation. 
Before or after crosslinking, or during crosslinking (particularly during 
melt-kneading), there may be added, if necessary, fillers such as carbon 
black, calcium carbonate, silica, metallic fibers and carbon fibers, as 
well as additives such as antioxidant, flame retardant and coloring agent, 
and paraffinic, naphthenic or aromatic mineral oils for assisting the 
dispersion of the fillers and enhancing flexibility and elasticity. 
Further, various kinds of resins and rubbers may be added, if necessary, in 
amounts 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 
following characteristics. 
(a) Superior in fluidity, so easy to mold, giving molded products having 
good appearance. 
(b) Superior in heat and oil resistance. 
(c) Small permanent elongation makes deformation difficult. 
(d) Superior in flexibility. 
(e) Low density and very light weight. 
Since the thermoplastic elastomer composition of the present invention has 
such excellent characteristics, its application range is extremely wide. 
The following are application examples thereof: 
(a) automobile interior sheet, mud guard, lace and cover 
(b) electric wire coating material 
(c) components of various electric appliances 
(d) hose 
(e) various packings 
(f) window frame sealing material 
(g) sound insulating material 
(h) modifier for various polymers 
The following examples are given to further illustrate the present 
invention, but the invention is not limited thereto. In the following 
working examples and comparative examples, physical properties were 
measured in the following manner. 
[Measurement by DSC] 
A hot-pressed 100 .mu.m thick film as a specimen is heated to 170.degree. 
C. and held at this temperature for 15 minutes, followed by cooling to 
0.degree. C. at a rate of 2.5.degree. C./min. Then, from this state the 
temperature is raised to 170.degree. C. at a rate of 10.degree. C./min and 
measurement is made. The vertex position of the maximum peak of peaks 
appearing during the heat-up period from 0.degree. to 170.degree. C. is 
regarded as the maximum peak temperature (Tm). 
[How to Determine Insolubles in Boiling n-Hexane] 
A 200 .mu.m 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 (50.degree. C., 7 hours), then the percentage insolubles 
(C.sub.6 insoluble) in boiling n-hexane is calculated in accordance with 
the following equation: 
##EQU1## 
[Preparing Test Sheet] 
Each resin composition obtained is placed in a mold 2 mm thick, 150 mm long 
and 150 mm wide, preheated at 210.degree. C. for 5 minutes, then 
pressure-molded for 5 minutes at the same temperature and at 150 
kg/cm.sup.2, and thereafter cooled for 10 minutes at 30.degree. C. under 
the pressure of 150 kg/cm.sup.2, followed by annealing at 50.degree. C. 
for 20 hours and allowing to stand at room temperature for 24 hours. 
Thereafter, physical properties are measured. 
Flow Parameter: FP] 
##EQU2## 
The larger the value of FP, the better the flowing property. 
[Tensile Test] 
Test piece is prepared using No.3 dumbbell in accordance with JIS K 6301 
and it is measured for tensile strength at a pulling rate of 50 mm/min. 
[Permanent Elongation] 
Test piece is prepared using No. dumbbell in accordance with JIS K 6301. It 
is held at 100% elongated state for 10 minutes, then contracted suddenly 
and allowed to stand for 10 minutes to check percentage elongation, from 
which is determined a elongation. 
[Softening Point]A 3 mm thick specimen is prepared in accordance with the 
test sheet preparing method and it is used for measurement A heat transfer 
medium is heated at a rate of 50.degree. C./min while applying a load of 
250 g through a needle-like indenter placed perpendicularly to the 
specimen in a heating bath, 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. 
[Hardness] 
Test piece is prepared in accordance with JIS K 6301 and measured for 
hardness using type A and type C testing machines. 
[Gel Percentage] 
A 200 .mu.m thick sheet is prepared using a hot press (at 200.degree. C. 
for 5 minutes), from which three 40 mm.times.20 mm sheets are cut out. The 
three sheets are each placed in a 120-mesh wire gauze bag and extracted in 
boiling xylene for 5 hours using a double-tube type Soxhlet extractor. 
Boiling xylene insolubles are taken out and vacuum-dried (80.degree. C., 7 
hours) to determine the percentage thereof as a gel percentage.

EXAMPLE 1 
As ethylene/butene-1 copolymer 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 from a substantially anhydrous magnesium chloride, 
1,2-dichloroethane and titanium tetrachloride. 
The ethylene/butene-1 copolymer thus obtained was found to have an ethylene 
content of 88.3 mol %, a melt index of 0.9 g/10 min, a density of 0.896 
g/cm.sup.3, a maximum peak temperature according to DSC of 119.8.degree. 
C. and a boiling n-hexane insolubles content of 82 wt. %. 
Separately, ethylene, propylene and ethylidene norbornene (ENB) were 
copolymerized using a vanadyl trichloride-ethylaluminum sesquichloride 
catalyst to obtain a copolymer rubber. This copolymer rubber was found to 
have a Mooney viscosity (ML.sub.1+4, 100.degree. C.) of 90, a propylene 
content of 27 wt. %, a density of 0.863 g/cm.sup.3 and an ENB content of 
16 in terms of iodine value. 
50 parts by weight of a propylene-ethylene random copolymer (ethylene 
content: 5.9 mol %) having a melt flow rate of 7 g/10 min, 100 parts by 
weight of the ethylene-propylene-ENB copolymer rubber, 0.5 wt. % of 
di(t-butylperoxy)dipropylbenzene (crosslinking agent), 0.1 wt. % of 
Irganox 1010 (antioxidant, a product of Ciba Geigy AG) and 0.15 wt. % of 
calcium stearate (lubricant)(each weight percent is based on 100 parts by 
weight of all the polymers in the final crosslinked composition) were 
dry-blended and then introduced into a Bumbury's mixer preheated to 
200.degree. C., in which kneading was performed for 10 minutes at 40 rpm. 
Then, 50 parts by weight of the ethylene/butene-1 copolymer was added and 
kneading was performed again at 200.degree. C. for 10 minutes to obtain a 
thermoplastic elastomer composition. This composition was measured for 
physical properties. The results of the measurement are as shown in Table 
1. 
EXAMPLES 2 AND 3 
The procedure of Example 1 was repeated except that the proportion of the 
ethylene-propylene-ENB copolymer rubber was changed as shown in Table 1. 
The resultant composition was measured for physical properties, the 
results of which are as shown in Table 1. 
EXAMPLE 4 
The procedure of Example 1 was repeated except that the amount of the 
ethylene/butene-1 copolymer and that of the propylene-ethylene random 
copolymer were changed to 60 parts and 40 parts by weight, respectively. 
The resultant composition was measured for physical properties, the 
results of which are as shown in Table 1. 
EXAMPLE 5 
The procedure of Example 1 was repeated except that the amount of the 
ethylene/butene-1 copolymer and that of the propylene-ethylene random 
copolymer were changed to 40 parts and 60 parts by weight, respectively. 
The resultant composition was measured for physical properties, the 
results of which are as shown in Table 1. 
EXAMPLE 6 
The procedure of Example 1 was repeated except that a propylene-ethylene 
block copolymer (ethylene content: 5.3 mol %) having a melt flow rate of 8 
g/10 min was used as the propylene polymer. The resultant composition was 
measured for physical properties, the results of which are as shown in 
Table 1. 
EXAMPLE 7 
The procedure of Example 1 was repeated except that a propylene homopolymer 
(melt flow rate: 1 g/10 min) was used as the propylene polymer. The 
resultant composition was measured for physical properties, the results of 
which are as set out in Table 1. 
EXAMPLE 8 
50 parts by weight of the ethylene/butene-1 copolymer used in Example 1, 50 
parts by weight of the propylene-ethylene random copolymer used in Example 
1, 100 parts by weight of a copolymer rubber having a Mooney viscosity of 
45, and the same proportions as in Example 1 of the crosslinking agent, 
antioxidant and lubricant were dry-blended and kneaded in a Bumbury's 
mixer at 200.degree. C. for 20 minutes to obtain a thermoplastic elastomer 
composition. The resultant composition was measured for physical 
properties, the results of which are as set out in Table 1. 
EXAMPLE 9 
An ethylene-propylene copolymer was prepared by copolymerizing ethylene and 
propylene in the presence of a catalyst comprising a solid catalyst 
component and triethylaluminum, the solid catalyst component having been 
obtained from a substantially anhydrous magnesium chloride, anthracene and 
titanium tetrachloride. 
The ethylene-propylene copolymer thus obtained was found to have an 
ethylene content of 85.5 mol %, a melt index of 1.0 g/10 min, a density of 
0.890 g/cm.sup.3, a maximum peak temperature according to DSC of 
121.6.degree. C. and a boiling n-hexane insolubles content of 58 wt. %. 
An elastomer composition was obtained in the same way as in Example 1 
except that the ethylene-propylene copolymer prepared above was used in 
place of the ethylene/butene-1 copolymer. The results of measurement of 
its physical properties are as set out in Table 1. 
COMATIVE EXAMPLE 1 
The procedure of Example 1 was repeated except that the amount of the 
ethylene/butene-1 copolymer and that of the propylene-ethylene random 
copolymer were changed to 20 parts and 80 parts by weight, respectively. 
The resultant coposition was measured for physical properties, the results 
of which are as set out in Table 1. 
COMATIVE EXAMPLE 2 
The procedure of Example 1 was repeated except that the amount of the 
ethylene/butene-1 copolymer and that of the propylene-ethylene random 
copolymer were changed to 80 parts and 20 parts by weight, respectively. 
The resultant composition was measured for physical properties, the 
results of which are as set out in Table 1. 
COMATIVE EXAMPLE 3 
The procedure of Example 1 was repeated except that the amount of the 
ethylene-propylene-ENB copolymer rubber was changed to 30 parts by weight. 
Physical properties of the resultant composition were measured, the 
results of which are as set out in Table 1. 
COMATIVE EXAMPLE 4 
The procedure of Example 1 was repeated except that the amount of the 
ethylene-propylene-ENB copolymer rubber was changd to 300 parts by weight. 
Physical properties of the resultant composition were measured, the 
results of which are as set forth in Table 1. 
COMATIVE EXAMPLE 5 
The procedure of Example 1 was repeated except that the crosslinking agent 
was not added. Physical properties of the resultant composition were 
measured, the results of which are as set forth in Table 1. 
COMATIVE EXAMPLE 6 
The procedure of Example 1 was repeated except that the ethylene/butene-1 
copolymer was replaced by a straight-chain, low density polyethylene 
(LINIREX AF 2320, a product of Nippon Petrochemicals Co., Ltd., melt index 
1.0 g/10 min, density 0.922 g/cm.sup.3, DSC maximum peak temperature 
122.1.degree. C., boiling n-hexane insolubles content 98.8 wt. %). 
Physical properties of the resultant composition were measured, the 
results of which are as set forth in Table 1. 
TABLE 1 
__________________________________________________________________________ 
Ethylene/.alpha.-Olefin Copolymer (A) Copolymer 
Boiling 
Propylene Polymer (B) 
Rubber (C) 
n-Hexane 
Type of Comononer 
Mooney 
Melt Index 
Density 
Tm Insolubles 
Copolymer- 
MFR Content 
Viscosity 
Monomer*1 
(g/10 min) 
(g/cm.sup.3) 
(.degree.C.) 
(wt. %) 
ization 
(g/10 min) 
(mol %) 
ML.sub.1+ 4, 
100.degree. 
__________________________________________________________________________ 
C. 
Example 1 
C'.sub.2 -C'.sub.4 
0.9 0.896 119.8 
82 Random 
7 Ethylene 
909 
Example 2 
" " " " " " " " 
Example 3 
" " " " " " " " " 
Example 4 
" " " " " " " " " 
Example 5 
" " " " " " " " " 
Example 6 
" " " " " Block 8 Ethylene 
".3 
Example 7 
" " " " " Homo 1 -- " 
Example 8 
" " " " " Random 
7 Ethylene 
459 
Example 9 
C'.sub.2 -C'.sub.3 
1.0 0.890 121.6 
58 " " " 90 
Comparative 
C'.sub.2 -C'.sub.4 
0.9 0.896 119.8 
82 " " " " 
Example 1 
Comparative 
" " " " " " " " " 
Example 2 
Comparative 
" " " " " " " " " 
Example 3 
Comparative 
" " " " " " " " " 
Example 4 
Comparative 
" " " " " " " " " 
Example 5 
Comparative 
LLDPE 1.0 0.922 122.1 
98.8 
" " " " 
Example 6 
__________________________________________________________________________ 
Thermoplastic Elastomer Compositions 
Blending 
Melt Flow 
Melt Flow Perma- 
Vicat 
Ratio Rate Rate Tensile 
nent Soften- Gel 
((A)/(B)/(C)) 
230.degree. C., 
230.degree. C., 
Tensile 
Elonga- 
Elonga- 
ing Percent- 
(part by 
2.16 kg 
21.6 kg Strength 
tion tion Point 
Hardness 
age 
weight) (g/10 min) 
(g/10 min) 
FP (kg/cm.sup.2) 
(%) (%) (.degree.C.) 
JIS A/C 
(wt. 
__________________________________________________________________________ 
%) 
Example 1 
50/50/100 
0.10 88 880 132 570 18 116 88/55 39 
Example 2 
50/50/80 
0.13 97 750 151 610 20 119 90/58 42 
Example 3 
50/50/150 
0.05 47 940 76 400 13 108 82/47 50 
Example 4 
60/40/100 
0.16 61 380 102 490 15 117 86/48 41 
Example 5 
40/60/100 
0.25 103 410 138 540 20 121 90/57 38 
Example 6 
50/50/100 
0.20 94 470 130 580 18 118 90/56 40 
Example 7 
50/50/100 
0.20 128 640 122 530 21 135 91/59 48 
Example 8 
50/50/100 
0.04 43 1080 150 580 18 117 90/58 53 
Example 9 
50/50/100 
0.14 102 730 101 510 18 114 82/53 30 
Comparative 
20/80/100 
0.18 130 720 145 640 25 117 &gt;100/70 
28 
Example 1 
Comparative 
80/20/100 
0.02 18 900 80 740 15 77 79/37 26 
Example 2 
Comparative 
50/50/30 
0.08 101 1260 180 550 35 105 &gt;100/83 
10 
Example 3 
Comparative 
50/50/300 
0.01 or 
9 -- 34 320 10 64 58/28 51 
Example 4 less 
Comparative 
50/50/100 
0.8 146 180 118 770 19 68 84/52 0 
Example 5 
Comparative 
50/50/100 
0.20 80 400 115 800 20 104 95/60 28 
Example 6 
__________________________________________________________________________ 
*1 C'.sub.2 : ethylene, 
C'.sub.3 : propylene, 
C'.sub.4 : butene1, 
LLDPE: linear low density polyethylene