Polypropylene resin composition and non-stretched film thereof

A polypropylene resin composition capable of bringing about a non-stretched film superior in the transparency, in the impact resistance, in the low temperature heat-sealability and in the strength of heat-sealing, which composition comprises (A) a polypropylene resin, (B) a specific ethylene/.alpha.-olefin random copolymer and (C) a specific propylene/ethylene/1-butene random copolymer.

FIELD OF THE INVENTION
 The present invention relates to a polypropylene resin composition and to a
 non-stretched film made of such resin composition. Specifically, the
 invention relates to a polypropylene resin composition comprising a
 polypropylene resin, a specific ethylene/.alpha.-olefin random copolymer
 and a specific propylene/ethylene/1-butene random copolymer, as well as to
 a non-stretched film made of such resin composition.
 BACKGROUND OF THE INVENTION
 Films of polypropylene resins have, due to their favorable performances in
 the mechanical properties, such as tensile strength, stiffness and so on,
 in the optical properties, such as gloss, transparency and the like and in
 the hygienic acceptability as the material for dealing with food products
 by, such as, non-toxicity and odorless property, found their wide uses in
 the field of packaging of food products.
 It has been practised here to incorporate in the resin a rubbery component,
 such as an ethylene/propylene copolymer, ethylene/butene copolymer or the
 like, since a film made solely of a polypropylene resin exhibits an
 inferior impact resistance and permits to effect heat sealing only at
 higher temperatures.
 While an addition of a rubbery component may improve the impact resistance
 and may permit to lower the heat-sealing temperature, it is accompanied by
 a shortcoming that the transparency of the resulting film will be
 deteriorated and the strength of heat sealing becomes decreased.
 SUMMARY OF THE INVENTION
 An object of the present invention is to provide a polypropylene resin
 composition for non-stretched film capable of bringing about a
 non-stretched film superior in the transparency, in the impact resistance,
 in the low temperature heat-sealability and in the strength of
 heat-sealing.
 Another object of the present invention is to provide a non-stretched film
 superior in the transparency, in the impact resistance, in the low
 temperature heat-sealability and in the strength of heat-sealing.
 The present invention provides for a polypropylene resin composition for
 non-stretched film as well as for a non-stretched film given below:
 (1) A polypropylene resin composition for non-stretched film, comprising
 (A) 50-95 parts by weight of a polypropylene resin,
 (B) 3-40 parts by weight of an ethylene/.alpha.-olefin random copolymer
 with the .alpha.-olefin having at least three carbon atoms, the said
 random copolymer having a content of the structural unit of ethylene of
 60-95 mole %, a density of 0.900 g/cm.sup.3 or lower, an MFR (melt flow
 rate, determined according to ASTM D-1238 at 190.degree. C. under a load
 of 2.16 kg) of 0.1-50 g/10 min. and a molecular weight distribution
 expressed by Mw/Mn, determined by gel permeation chromatography(GPC), of 3
 or less, and
 (C) 2-20 parts by weight of a propylene/ethylene/1-butene random copolymer,
 which meets the three conditions 1), 2) and 3) given below,
 wherein the amounts of (A), (B) and (C) sum up to 100 parts by weight and
 wherein the said random copolymer (C) meets the following three
 conditions, namely,
 condition 1) that it comprises 50-88 mole % of propylene unit, 2-30 mole %
 of ethylene unit and 10-40 mole % of 1-butene unit and that the content of
 1-butene unit is greater than the content of ethylene unit;
 condition 2) that it has an MFR, determined according to ASTM D-1238 at
 230.degree. C. under a load of 2.16 kg, of 0.1-50 g/10 min.; and
 condition 3) that it has a molecular weight distribution expressed by
 Mw/Mn, determined by gel permeation chromatography (GPC), of 3 or less.
 (2) A polypropylene resin composition for non-stretched film as defined in
 the above (1), wherein the polypropylene resin (A) comprises at least one
 selected from the group consisting of propylene homopolymers,
 propylene/.alpha.-olefin random copolymers having a content of the
 .alpha.-olefin other than propylene of 10 mole % or lower and
 propylene/.alpha.-olefin block-copolymers having a content of
 n-decane-extractable portion of 10% by weight or less.
 (3) A polypropylene resin composition for non-stretched film as defined in
 the above (1) or (2), wherein the ethylene/.alpha.-olefin random copolymer
 (B) is an ethylene/butene random copolymer having an ethylene unit content
 of 60-95 mole % and a 1-butene unit content of 5-40 mole %.
 (4) A non-stretched film made of a polypropylene resin composition as
 defined in either one of the above (1) to (3).
 DETAILED DESCRIPTION OF THE INVENTION
 Below, the polypropylene resin composition for non-stretched film and the
 non-stretched film according to the present invention will be described in
 detail.
 The polypropylene resin composition for non-stretched film according to the
 present invention comprises a polypropylene resin (A), an
 ethylene/.alpha.-olefin random copolymer (B) and a
 propylene/ethylene/1-butene random copolymer (C).
 The non-stretched film according to the present invention is made of the
 above polypropylene resin composition.
 First, the description is directed to the polypropylene resin (A) composing
 the polypropylene resin composition.
 According to the present invention, any voluntary one among known
 polypropylene resins can be chosen for the polypropylene resin (A). For
 such a polypropylene resin (A), there may be enumerated, for example,
 homopolymers of propylene and random copolymers and block-copolymers of
 propylene/.alpha.-olefin with the .alpha.-olefin being other than
 propylene. The polypropylene resin (A) may be modified with a monomer
 having polar group(s), such as maleic anhydride or so on.
 Favorable polypropylene resins (A) comprises at least one selected from the
 group consisting of homopolymers of propylene, propylene/.alpha.-olefin
 random copolymers containing at the most 10 mole %, preferably 8 mole % or
 less, of other .alpha.-olefin unit and propylene/.alpha.-olefin
 block-copolymer having a content of n-decane-extractable portion, namely,
 a portion to be extracted by n-decane, of 10% by weight or less,
 especially 8% by weight or less.
 In the context of this specification, it is meant by the ".alpha.-olefin
 unit" a structural unit derived from an .alpha.-olefin in a polymer. The
 same applies also to the "ethylene unit", "propylene unit" and "1-butene
 unit". In the present invention, .alpha.-olefin encompasses ethylene.
 As the .alpha.-olefins composing the propylene/.alpha.-olefin random
 copolymer or the propylene/.alpha.-olefin block-copolymer, there may
 favorably be enumerated .alpha.-olefins having 2-20 carbon atoms other
 than propylene and concrete examples thereof include ethylene, 1-butene,
 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene, 1-dodecene,
 1-hexadecene and 4-methyl-1-pentene. These .alpha.-olefins may be
 incorporated either solely or in a combination of two or more of them.
 The polypropylene resin (A) to be employed according to the present
 invention can be produced by processes known per se using a solid titanium
 catalyst or a metallocene catalyst known per se.
 It is favorable that the polypropylene resin (A) has a degree of
 crystallinity, determined by X-ray diffraction method, of at least 40%,
 especially at least 50%, and a melting point (Tm), determined by DSC
 method, in the range of 100-165.degree. C. It is preferable to incorporate
 a polypropylene resin (A) having a melting point higher than that of the
 ethylene/.alpha.-olefin random copolymer (B) and that of the
 propylene/ethylene/1-butene random copolymer (C).
 The polypropylene resin (A) has a melt flow rate (MFR), determined in
 accordance with ASTM D 1238 at 230.degree. C. under a load of 2.16 kg, in
 the range of, usually, 0.1-300 g/10 min., preferably 1-50 g/10 min.
 The polypropylene resin (A) may be incorporated either alone or in a
 combination of two or more.
 Now, the ethylene/.alpha.-olefin random copolymer (B) will be described.
 The ethylene/.alpha.-olefin random copolymer (B) has characteristic
 features of
 1) a content of the ethylene unit in the range of 60-95 mole %, preferably
 70-90 mole %,
 2) a density of 0.900 g/cm.sup.3 or less, preferably in the range of
 0.850-0.880 g/cm.sup.3,
 3) an MFR (melt flow rate, determined according to ASTM D 1238 at
 190.degree. C. under a load of 2.16 kg) in the range of 0.1-50 g/10 min.,
 preferably 0.2-30 g/10 min., especially preferably 0.5-10 g/10 min., and
 4) a molecular weight distribution expressed by Mw/Mn, determined by gel
 permeation chromatography (GPC) using o-dichlorobenzene as the eluent and
 monodisperse polystyrenes as the standard, of 3 or less.
 The .alpha.-olefin in the ethylene/.alpha.-olefin random copolymer (B) has
 3 or more carbon atoms, preferably 3-20 carbon atoms, especially
 preferably 3-8 carbon atoms.
 As concrete examples of the .alpha.-olefin, there may be enumerated
 propylene, 1-butene, 1-pentene, 1-hexene, 4-methyl-1-pentene, 1-heptene,
 1-octene, 1-nonene, 1-decene, 1-undecene, 1-dodecene, 1-tridecene,
 1-tetradecene, 1-pentadecene, 1-hexadecene, 1-heptadecene, 1-nonadecene,
 1-eicosene, 9-methyl-1-decene, 11-methyl-1-dodecene,
 12-ethyl-1-tetradecene. They may be employed either alone or in a
 combination of two or more.
 By compounding the ethylene/.alpha.-olefin random copolymer as above
 together with the propylene/ethylene/1-butene random copolymer (C) and
 with the polypropylene resin (A), a resin composition superior in the low
 temperature impact resistance, in the low temperature heat-sealability and
 in the transparency can be obtained.
 It is favorable that the ethylene/.alpha.-olefin random copolymer (B) has a
 degree of crystallinity, determined by X-ray diffraction method, of,
 preferably, lower than 40%, more preferably not higher than 30%. By using
 an ethylene/.alpha.-olefin random copolymer (B) having a degree of
 crystallinity lower than 40%, a film superior in the low temperature
 heat-sealability and in the impact resistance (a superior film impact
 strength characteristic) can be obtained.
 The ethylene/.alpha.-olefin random copolymer (B) has preferably a parameter
 (B-value) for the randomness of chain distribution of monomeric units in
 the copolymer, determined by .sup.13 C-NMR, in the range of 1.0-1.4. The
 B-value is a parameter indicating the state of compositional distribution
 of structural units in the molecular chain of the copolymer and can be
 calculated according to the following equation (I).
EQU B=POE/(2.multidot.PO.multidot.PE) (I)
 In this equation, PE and PO represent the mole fractions of the ethylene
 units and the .alpha.-olefin units, respectively, in the
 ethylene/.alpha.-olefin random copolymer and POE is a proportion of number
 of ethylene/.alpha.-olefin alternating chains in the total number of dyad
 chains.
 The values for PE, PO and POE can be calculated in the practice as follows:
 A sample of an ethylene/.alpha.-olefin random copolymer (B) is prepared by
 dissolving 200 mg of the random copolymer homogeneously in 1 ml of
 hexachlorobutadiene in a 10 mm .phi. test tube, whereupon .sup.13 C-NMR
 spectrum of this sample is observed under the following conditions:

examination temperature 120.degree. C.
 examination frequency 20.05 MHz
 breadth of spectral line 1500 Hz
 width of filter 1500 Hz
 pulse repetition interval 4.2 sec.
 pulse width 7 .mu. sec.
 number of integration 2,000-5,000
 The values of PE, PO and POE can be determined according to the methods
 reported, for example, by G. J. Ray {"Macromolecules", 10, 773 (1977)}, by
 J. C. Randall {"Macromolecules", 15, 353 (1982)} and by K. Kimura
 {"Polymer", 25, 4418 (1984)}, based on the .sup.13 C-NMR spectrum observed
 as above.
 The B-value equals 2, when both the comonomer units are ideally alterating
 in the ethylene/.alpha.-olefin random copolymer, and equals to zero, when
 both the comonomer units are present in the copolymer as ideal
 block-copolymer by being completely separately polymerized.
 When an ethylene/.alpha.-olefin random copolymer (B) having a B-value in
 the range of 1.0-1.4 is used, a polypropylene resin composition exhibiting
 superior heat resistance can be obtained.
 The ethylene/.alpha.-olefin random copolymer (B) may favorably have an
 intrinsic viscosity [.eta.], determined in decalin (decahydronaphthalene)
 at 135.degree. C., in the range of 0.5-5.0 dl/g.
 As the ethylene/.alpha.-olefin random copolymer (B), a branched long chain
 type copolymer having a g.eta.*-value (See Japanese Patent Laid Open Sho
 58-191705 A), defined by the equation (II) given below, in the range of
 0.2 to 0.95 or a linear chain copolymer having a g.eta.*-value exceeding
 0.95 may be preferred.
EQU g.eta.*=[.eta.]/[.eta.].sub.blank (II)
 In the equation (II), [.eta.] represents the intrinsic viscosity of the
 ethylene/.alpha.-olefin random copolymer (B) determined in decalin at
 135.degree. C. and [.eta.].sub.blank denotes the intrinsic viscosity of a
 linear chain ethylene/propylene random copolymer used as the standard
 which has an ethylene content of 70 mole % and a weight-average molecular
 weight (by light scattering method) identical with that of the
 ethylene/.alpha.-olefin random copolymer having the intrinsic viscosity
 [.eta.] measured as above.
 As the ethylene/.alpha.-olefin random copolymer (B) of branched long chain
 type having a g.eta.*-value of 0.2-0.95, those which are produced using a
 metallocene catalyst comprising a metallocene represented by the formula
 (2) as will be described afterwards are preferred.
 As the ethylene/.alpha.-olefin random copolymer (B) of linear chain type
 having a g.eta.*-value exceeding 0.95, those which are produced using a
 metallocene catalyst comprising the metallocene represented by the formula
 (1) or using a metallocene catalyst comprising a metallocene represented
 by the formula (2), as will be described afterwards, in which R.sup.41
 -R.sup.44 may form a ring by combining a part of each of the groups
 adjoining each other together with the carbon atoms bound thereto are
 preferred.
 When an ethylene/.alpha.-olefin random copolymer (B) having the
 characteristic features given above is employed, a polypropylene resin
 composition superior in the mechanical strength, in the weatherability, in
 the ozone-fastness, in the low temperature-flexibility and in the heat
 resistance can be obtained. When, in particular, an
 ethylene/.alpha.-olefin random copolymer (B) of branched long chain type
 having a g.eta.*-value in the range of 0.2-0.95 is employed, a
 polypropylene resin composition which is superior especially in the
 moldability can be obtained and, when an ethylene/.alpha.-olefin random
 copolymer (B) of linear chain type having a g.eta.*-value exceeding 0.95
 is employed, a polypropylene resin composition especially superior in the
 film-impact performance can be obtained. When an ethylene/.alpha.-olefin
 random copolymer (B) of an .alpha.-olefin of 6-10 carbon atoms is
 employed, a polypropylene resin composition superior in the mechanical
 strength, in the low temperature flexibility and in the heat resistance
 can be obtained.
 While the ethylene/.alpha.-olefin random copolymer (B) as mentioned above
 can be obtained by co-polymerizing ethylene with an .alpha.-olefin in the
 presence of a catalyst based on vanadium or titanium, such an
 ethylene/.alpha.-olefin random copolymer is preferred, that is produced
 using a metallocene catalyst which will be described afterwards.
 As the vanadium-based catalyst to be used for producing the
 ethylene/.alpha.-olefin random copolymer (B), preference is given to those
 which are composed of a soluble vanadium compound and an alkylaluminum
 halide.
 As the soluble vanadium compound for the vanadium-based catalyst, there may
 be exemplified concretely vanadium tetrachlodide, vanadiumoxy trichloride,
 monoethoxyvanadium dichloride, triacetylacetonatovanadium and
 triacetylacetonato-oxyvanadium.
 As the alkylaluminum halide for the vanadium-based catalyst, there may be
 exemplified concretely ethylaluminum dichloride, diethylaluminum
 monochloride, ethylaluminum sesquichloride, diethylaluminum monobromide,
 diisobutylaluminum monochloride, isobutylaluminum dichloride and
 isobutylaluminum sesquichloride.
 For the catalyst based on titanium mentioned above for producing the
 ethylene/.alpha.-olefin random copolymer (B), preference is given to a
 catalyst to be used for olefin polymerization, which is prepared from a
 solid titanium catalyst component and an organometallic compound catalyst
 component together with an optionally incorporated electron donor.
 As the solid titanium catalyst component for olefin polymerization, for
 example, those in which titanium trichloride or a composition containing
 titanium trichloride is supported on a carrier, e.g. one which has a
 specific surface area of 100 m.sup.2 /g or more, or those in which
 magnesium, a halogen, an electron donor (preferably an aromatic carboxylic
 acid ester or an alkyl group-containing ether) and titanium are included
 as the indispensable components by being supported on a carrier, e.g. one
 which has a specific surface area of 100 m.sup.2 /g or greater. Among
 them, the solid titanium catslyst component of the latter is preferred.
 For the organometallic compound catalyst component of the catalyst for
 olefin polymerization as mentioned above, organoaluminum compounds are
 employed favorably. Concretely, there may be enumerated, for example,
 trialkylaluminums, dialkylaluminum halides, alkylaluminum sesquihalides
 and alkylaluminum dihalides. These organoaluminum compounds may be chosen
 adequately in accordance with each specific solid titanium catalyst
 component employed.
 For the electron donor of the catalyst for olefin polymerization as
 mentioned above, various organic compounds containing nitrogen atom,
 phosphorus atom, sulfur atom, silicium atom or boron atom may be used,
 wherein esters and ethers containing such atoms may favorably be
 enumerated.
 The catalyst for olefin polymerization may be activated by, for example,
 co-crushing, and may be used after being subjected to a prepolymerization
 of an olefin.
 Now, the description will be directed to the propylene/ethylene/1-butene
 random copolymer (C).
 As mentioned previously, the propylene/ethylene/1-butene random copolymer
 (C) should meet the three conditions 1) to 3) given previously. These
 conditions are described below in order.
 In the condition 1), the chemical composition of the
 propylene/ethylene/1-butene random copolymer (C) is specified.
 Thus, the propylene/ethylene/1-butene random copolymer (C) should comprise
 50-88 mole % of the propylene unit, 2-30 mole % of the ethylene unit and
 10-40 mole % of the 1-butene unit, wherein it comprises preferably 60-85
 mole % of the propylene unit, 3-20 mole % of the ethylene unit and 10-30
 mole % of the 1-butene unit, particulartly preferably 60-85 mole % of the
 propylene unit, 3-20 mole % of the ethylene unit and 12-30 mole % of the
 1-butene unit. Here, the content of the 1-butene unit should be greater
 than that of the ethylene unit.
 By adjusting the chemical composition of the propylene/ethylene/1-buten
 random copolymer (C) to the above proportion, the copolymer (C) will have
 a better balance between the elastomeric property, on the one hand, and
 the compatibilities of the copolymer (C) with the polypropylene resin (A)
 and with the ethylene/.alpha.-olefin random copolymer (B), on the other
 hand.
 The propylene/ethylene/1-butene random copolymer (C) may contain further
 .alpha.-olefin unit(s) other than the propylene unit, the 1-butene unit
 and the ethylene unit in a small proportion within a limit not obstructing
 the advantageous feature mentioned above, such as for example, 10 mole %
 or less.
 The conditions 2) and 3) prescribe the melt flow rate (MFR) as an index for
 the molecular weight and the molecular weight distribution (Mw/Mn),
 respectively, of the propylene/ethylene/1-butene random copolymer (C).
 The MFR, determined at 230.degree. C. under a load of 2.16 kg according to
 ASTM D 1238, of the propylene/ethylene/1-butene random copolymer (C)
 should be in the range of 0.1-50 g/10 min., preferably 0.2-30 g/10 min.,
 especially preferably 0.1-10 g/10 min.
 The Mw/Mn ratio of the propylene/ethylene/1-butene random copolymer (C)
 should be not higher than 3. The Mw/Mn ratio is a value converted into a
 polystyrene-based value and can be determined by a gel permeation
 chromatography (GPC) using o-chlorobenzene as the elution solvent and
 using monodisperse dispersions of polystyrenes as the standard.
 The molecular weight distribution expressed by Mw/Mn can be determined
 using a GPC apparatus, for example GPC-150C of the firm Water Co. by the
 following procedures. Thus, using TSK GNH TH (trademark, of TOSO K.K.,
 with a column size of 7.8 mm diameter and 600 mm length) as a separation
 column, a gel permeation chromatography is effected at a column
 temperature of 140.degree. C. using o-dichlorobenzene as the mobile phase
 and 0.025% by weight of BHT as the antioxidant at a sample concentration
 of 0.1% by weight and a feed rate of 1.0 ml/min. in a sample charge amount
 of 500 .mu.l under the use of a differential refractometer as the
 detector. For the separation column, there may also be employed TSK GMH-HT
 or TSK GMH-HTL (trademarks) of TOSO K.K. As the standard polystyrene
 monodisperse dispersion, one available from the firm TOSO may be employed.
 When the propylene/ethylene/1-butene random copolymer (C) has an MFR and a
 molecular weight distribution within the above-indicated ranges, it has a
 superior compatibility with the polypropylene resin (A) and the resin
 composition containing such random copolymer (C) will exhibit better
 processibility upon molding with the resulting molded product of superior
 transparency with scarce surface tackiness.
 For the propylene/ethylene/1-butene random copolymer (C) according to the
 present invention, one which has a certain microstructure is preferred.
 Thus, the propylene/ethylene/1-butene random copolymer (C) may preferably
 contain i) a three-chain structure constituted exclusively of propylene
 unit with head-to-tail coupling or ii) a three-chain structure constituted
 of propylene unit with head-to-tail coupling and 1-butene unit. Among such
 random copolymer (C) having the three-chain structure i) or ii), such ones
 are preferred, in which the .sup.13 C-NMR observation (in a
 hexachlorobutadiene solution, on the basis of tetramethylsilane) for the
 side chain methyl group of the second propylene unit in the three-chain
 structure i) or ii) will show the integrated areas for the peaks found
 within the range of 21.2-21.7 ppm amounting at least 90%, preferably 92%
 or more, of the integrated areas of the total peaks appearing within the
 range of 19.7-21.7 ppm assumed to be 100%.
 For the propylene/ethylene/1-butene random copolymer (C), those in which
 the proportion of the site-irregular units caused by 2,1-insertion of
 propylene monomer, determined by .sup.13 C-NMR, is at least 0.05%,
 preferably 0.05-0.4%, more preferably 0.05-0.3%, of the total propylene
 units are favorable.
 For the propylene/ethylene/1-butene random copolymer (C), those in which
 the proportion of the site-irregular units caused by 1,3-insertion of
 propylene monomer is not higher than 0.05%. Upon the polymerization,
 propylene monomer will be incorporated by 1,2-insertion (the methylene
 side will combine with the catalyst as described afterwards), while in a
 rare case it may be incorporated by 2,1-insertion or 1,3-insertion. The
 propylene monomers incorporated by the 2,1-insertion or by the
 1,3-insertion constitute in the polymer chain site-irregular units.
 The proportion of the 2,1-inserted propylene monomers relative to the total
 propylene units can be determined by .sup.13 C-NMR in accordance with the
 teaching disclosed in "Polymer", 30, (1989) 1350 from the following
 mathematical equation (III):
EQU [Proportion of site-irregular units due to
 2,1-insertion]=[[0.25.multidot.I.alpha..beta..multidot.{Struct.(i)}+0.
 5.multidot.I.alpha..beta..multidot.{Struct.
 (ii)}].times.100].div.[I.alpha..alpha.+I.alpha..beta..multidot.{Struct.
 (ii)}+0.5.multidot.[I.alpha..gamma.+I.alpha..beta..multidot.{Struct.(i)}+I
 .alpha..delta.]] (III)
 Here, the nomenclature for the peaks are in accordance with the method of
 Carman et al: "Rubber Chem. Technol.", 44, (1971), 781. The symbols
 I.alpha..beta. etc. refer to the integrated peak area for the
 .alpha..beta. peak etc. When the integrated area for a peak is difficult
 to measure directly from the spectrum chart due to reasons, such as
 overlapping and the like, a carbon peak having corresponding area may be
 substituted therefor.
 The proportion of the three-chain structure caused by the 1,3-insertion of
 propylene in percent value can be calculated by dividing 1/2 of the
 integrated area of .beta..gamma. peak (resonating at around 27.4 ppm) by
 the sum of the integrated areas of the total peaks of methyl group plus
 1/2 of the integrated area of .beta..gamma. peak and multiplying the
 resulting quotient by 100.
 For the propylene/ethylene/1-butene random copolymer (C) according to the
 present invention, those which are produced using a metallocene catalyst
 are preferred.
 As the metallocene catalyst, those based on metallocene are preferred,
 which comprise
 I) (a) a transition metal compound of bridged type (in the following,
 denoted sometimes simply as a transition metal compound) represented by
 the following formula (1):
 ##STR1##
 In the Formula (1), M denotes a transition metal atom of Groups IV-VIB of
 the Periodic Table; R.sup.1, R.sup.2, R.sup.3 and R.sup.4 represent each,
 identical with or different from each other, a hydrogen atom, a halogen
 atom, a hydrocarbyl of 1-20 carbon atoms, a halogenated hydrocarbyl of
 1-20 carbon atoms, a silicium-containing group, an oxygen-containing
 group, a sulfur-containing group, a nitrogen-containing group or a
 phosphorus-containing group or may form a ring by combining a part of each
 of the groups adjoining each other together with the carbon atoms bound
 thereto; X.sup.1 and X.sup.2 stand each, identical with or different from
 each other, for hydrogen atom, a halogen atom, a hydrocarbyl of 1-20
 carbon atoms, a halogenated hydrocarbyl of 1-20 carbon atoms or an oxygen-
 or sulfur-containing group; Y represents a divalent hydrocarbyl of 1-20
 carbon atoms, a divalent halogenated hydrocarbyl of 1-20 carbon atoms, a
 divalent silisium- or germanium-containing group or stands for --O--,
 --CO--, --S--, --SO--, --SO.sub.2 --, --NR.sup.5 --, --P(R.sup.5)--,
 --P(.dbd.O)(R.sup.5)--, --BR.sup.5 -- or --AlR.sup.5 -- with R.sup.5 being
 hydrogen atom, a halogen atom, a hydrocarbyl of 1-20 carbon atoms or a
 halogenated hydrocarbyl of 1-20 carbon atoms, and
 II) at least one compound capable of activating the above-identified
 transition metal compound of bridged type (a) and selected from the group
 consisting of
 (b) an organoaluminum compound
 (C) an organoaluminum-oxy compound and
 (d) an ionizing ionic compound capable of forming an ion pair by reacting
 with the transition metal compound represented by the formula (1)
 In the formula (1), M denots a transition metal of the Groups IV-VIB and
 stands concretely for titanium, zirconium, hafnium, vanadium, niobium,
 tantalum, chromium, molybdenum, wolfram or so on, wherein preference is
 given to titanium, zirconium and hafnium with particular preference to
 zirconium.
 In the formula (1), R.sup.1, R.sup.2, R.sup.3 and R.sup.4 may be identical
 with or different from each other and stand each for hydrogen atom, a
 halogen atom, a hydrocarbon group which may be substituted by halogen, a
 silisium-, oxygen-, sulfur-, nitrogen- or phosphorus-containing group or
 may form a ring by combining a part of each of the adjoining groups
 together with the carbon atoms bound thereto. In the formula (1), the
 groups R.sup.1 to R.sup.4 given each in a pair suggest that it is
 preferable that the two of the same symbol will be coupled together when a
 ring is formed from them. Thus, a ring may preferably be formed from, for
 example, two R.sup.1 groups by being bound together.
 As the halogen atom represented by R.sup.1 -R.sup.4 in the formula (1),
 there may be exemplified fluorine, chlorine, bromine or iodine.
 As the hydrocarbyl of 1-20 carbon atoms represented by R.sup.1 to R.sup.4
 in the formula (1), there may be enumerated, for example, alkyl groups,
 such as methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, sec-butyl,
 tert-butyl, n-pentyl, neopentyl, n-hexyl, cyclohexyl, octyl, nonyl,
 dodecyl, eicosyl, norbornyl and adamantyl; alkenyl groups, such as vinyl,
 propenyl and cyclohexenyl; arylalkyl groups, such as benzyl, phenylethyl
 and phenylpropyl; and aryl groups, such as phenyl, tolyl, dimethylphenyl,
 trimethylphenyl, ethylphenyl, propylphenyl, biphenyl, .alpha.- and
 .beta.-naphthyls, methylnaphthyl, anthracenyl, phenanthryl, benzylphenyl,
 pyrenyl, acenaphthyl, phenalenyl, aceanthrylenyl, tetrahydronaphthyl,
 indanyl and biphenylyl.
 As the ring to be formed by combining these hydrocarbyl groups, there may
 be enumerated, for example, condensation rings, such as benzene ring,
 naphthalene ring, acenaphthene ring and indene ring; and ring groups in
 which hydrogen atom(s) on such a condensation ring are substituted by an
 alkyl group, such as methyl, ethyl, propyl or butyl. These hydrocarbyl
 groups may be substituted by halogen(s).
 The silicium-containing group represented by R.sup.1 -R.sup.4 in the
 formula (1) may stands for a hydrocarbyl-monosubstituted silyl, such as
 methylsilyl or phenylsilyl; a hydrocarbyl-disubstituted silyl, such as
 dimethylsilyl or diphenylsilyl; a hydrocarbyl-trisubstituted silyl, such
 as trimethylsilyl, triethylsilyl, tripropylsilyl, tricyclohexylsilyl,
 triphenylsilyl, dimethylphenylsilyl, methyldiphenylsilyl, tritolylsilyl or
 trinaphthylsilyl; a silyl ether of a hydrocarbyl-substituted silyl, such
 as trimethylsilyl ether; and a silicium-substituted aryl, such as
 trimethylsilylphenyl.
 As the oxygen-containing group represented by R.sup.1 to R.sup.4 in the
 formula (1), there may be enumerated, for example, hydroxy; alkoxy groups,
 such as methoxy, ethoxy, propoxy and butoxy; aryloxy groups, such as
 phenoxy, methylphenoxy, dimethylphenoxy and naphthoxy; and arylalkoxy
 groups, such as phenylmethoxy and phenylethoxy.
 As the sulfur-containing groups represented by R.sup.1 to R.sup.4 in the
 formula (1), there may be enumerated, for example, those in which the
 oxygen atom in the above-mentioned oxygen-containing groups is replaced by
 sulfur and sulfonate groups, such as methyl sulfonate, trifluoromethane
 sulfonate, phenyl sulfonate, benzyl sulfonate, p-toluene sulfonate,
 trimethylbenzene sulfonate, triisobutylbenzene sulfonate, p-chlorobenzene
 sulfonate and pentafluorobenzene sulfonate; and sulfinate groups, such as
 methyl sulfinate, phenyl sulfinate, benzene sulfinate, p-toluene
 sulfinate, trimethylbenzene sulfinate and pentafluorobenzene sulfinate.
 As the nitrogen-containing groups represented by R.sup.1 to R.sup.4 in the
 formula (1), there may be enumerated, for example, amino group; alkylamino
 groups, such as methylamino, dimethylamino, diethylamino, dipropylamino,
 dibutylamino and dicyclohexylamino; arylamino and alkylarylamino groups,
 such as phenylamino, diphenylamino, ditolylamino, dinaphthylamino and
 methylphenylamino.
 As the phosphorus-containing groups represented by R.sup.1 -R.sup.4 in the
 formula (1), there may be exemplified dimethylphosphino and
 diphenylphosphino.
 In the fromula (1), X.sup.1 and X.sup.2 may be identical with or different
 from each other and may stand each for hydrogen atom, a halogen atom, a
 hydrocarbyl which may be substituted by halogen(s) of 1-20 carbon atoms or
 an oxygen- or sulfur-containing group. As the atoms or the groups for
 them, there may concretely be enumerated those which are given for the
 atoms or the groups for R.sup.1 -R.sup.4.
 In the formula (1), Y represents a divalent hydrocarbyl group which may be
 substituted by halogen(s) of 1-20 carbon atoms, a divalent
 silicium-containing group, a divalent germanium-containing group, --O--,
 --CO--, --S--, --SO--, --SO.sub.2 --, --NR.sup.5 --, --P(R.sup.5)--,
 --P(O)(R.sup.5)--, --BR.sup.5 -- or --AlR.sup.5 -- with R.sup.5 being
 hydrogen atom, a halogen atom, a hydrocarbyl of 1-20 carbon atoms which
 may be substituted by halogen(s).
 As the hydrocarbyl of 1-20 carbon atoms which may be substituted by
 halogen(s) as represented by Y in the formula (1), there may be
 exemplified alkylene groups, such as methylene, dimethylmethylene,
 1,2-ethylene, dimethyl-1,2-ethylene, 1,3-trimethylene, 1,4-tetramethylene,
 1,2-cyclohexylene and 1,4-cyclohexylene; and arylalkylene groups, such as
 diphenyl-methylene and diphenyl-1,2-ethylene. There may further be
 enumerated halogenated hydrocarbyl groups, such as those in which the
 divalent hydrocarbyl of 1-20 carbon atoms given above are halogenated.
 As the divalent silicium-containing groups represented by Y in the formula
 (1), there may be exemplified alkylsilylenes, such as methylsilylene,
 dimethylsilylene, diethylsilylene, di(n-propyl)silylene,
 di(i-propyl)silylene, di(cyclohexyl)silylene, methylphenylsilylene,
 diphenylsilylene, di(p-tolyl)silylene and di(p-chlorophenyl)silylene;
 alkylarylsilylenes; arylsilylenes; alkyldisilyls, such as
 tetramethyl-1,2-disilyl and tetraphenyl-1,2-disilyl; alkylaryldisilyls and
 aryldisilyls.
 As the germanium-containing groups represented by Y in the formula (1),
 there may be exemplified those in which the silicium atom of the
 silicium-containing groups given above is replaced by germanium atom.
 In the following, concrete examples of the transition metal compound of
 bridged type (a) represented by the formula (1) are given:
 Bis(cyclopentadiaenyl)zirconium dichloride, bis(indenyl)zirconium
 dichloride, bis(fluorenyl)zirconium dichloride,
 bis(n-propylcyclopentadienyl)zirconium dichloride,
 bis(t-butylcyclopentadienyl)zirconium dichloride,
 bis(trimethylsilylcyclopentadienyl)zirconium dichloride,
 bis(neopentylcyclopentadienyl)zirconium dichloride,
 rac-dimethylsilylene-bis(1-cyclopentadienyl)zirconium dichloride,
 rac-dimethylsilylene-bis{1-(3-methylcyclopentadienyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,4-dimethylcyclopentadienyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,3,5-trimethylcyclopentadienyl)}zirconium
 dichloride and so on.
 According to the present invention, amoung the transition metal compound
 (a) represented by the formula (1), those bridged type compounds
 represented by the following formula (2) are used favorably.
 ##STR2##
 In the formula (2), M, R.sup.1, R.sup.3, X.sup.1, X.sup.2 and Y have the
 same meanings as defined for the formula (1) and R.sup.21 to R.sup.24 and
 R.sup.41 to R.sup.44 represent each hydrogen atom, a halogen atom, an
 alkyl group or an aryl group, wherein the alkyl and aryl groups may be
 substituted by halogen atom(s) or organosilyl group(s). The groups
 R.sup.41 to R.sup.44 may also form a ring by combining a part of each of
 the groups adjoining each other together with the carbon atoms bound
 thereto.
 In the following, concrete examples of the transition metal compound of
 bridged type represented by the formula (2) are given:
 rac-dimethylsilylene-bis[1-{2-n-propyl-4-(9-phenanthryl)indenyl}]zirconium
 dichloride, rac-ethylene-bis(1-indenyl)zirconium dichloride,
 rac-ethylene-bis(1-indenyl)zirconium dibromide,
 rac-ethylene-bis(1-indenyl)dimethylzirconium,
 rac-ethylene-bis(1-indenyl)diphenylzirconium,
 rac-ethylene-bis(1-indenyl)methylzirconium monochloride,
 rac-ethylene-bis(1-indenyl)zirconium-bis(methanesufonate),
 rac-ethylene-bis(1-indenyl)zirconium-bis(p-toluenesufonate),
 rac-ethylene-bis(1-indenyl)zirconium-bis(trifluoromethanesulfonate),
 rac-ethylene-bis{1-(4,5,6,7-tetrahydroindenyl)}zirconium dichloride,
 rac-isopropylidene-bis{1-indenyl)}zirconium dichloride,
 rac-dimethylsilylene-bis(1-indenyl)zirconium dichloride,
 rac-dimethylsilylene-bis{1-(2-methylindenyl)}zirconium dichloride,
 rac-dimethylsilylene-bis{1-(2-methyl-4-i-propylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-ethylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-n-propylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-n-butylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-sec-butylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-t-butylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-n-pentylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-n-hexylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-cyclohexylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-methylcyclohexylindenyl)}zircon
 ium dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-phenylethylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-phenyldichloromethylindenyl)}zi
 rconium dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-chloromethylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-trimethylsilylenemethylindenyl)
 }zirconium dichloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-trimethylsiloxymethylindenyl)}z
 irconium dichloride,
 rac-diethylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium
 dichloride,
 rac-di(i-propyl)silylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium
 dichloride,
 rac-di(n-butyl)silylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium
 dichloride,
 rac-di(cyclohexyl)silylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconiu
 m dichloride,
 rac-methylphenylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium
 dichloride,
 rac-methylphenylsilylene-bis{1-(2,7-dimethyl-4-t-butyl-indenyl)}zirconium
 dichloride,
 rac-diphenylsilylene-bis{1-(2,7-dimethyl-4-t-butylindenyl)}zirconium
 dichloride,
 rac-diphenylsilylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium
 dichloride,
 rac-diphenylsilylene-bis{1-(2,7-dimethyl-4-ethylindenyl)}zirconium
 dichloride,
 rac-di-(p-tolyl)silylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zirconium
 dichloride,
 rac-di-(p-chlorophenyl)silylene-bis{1-(2,7-dimethyl-4-i-propylindenyl)}zir
 conium dichloride,
 rac-dimethylsilylene-bis{1-(2-methyl-4-i-prop-yl-7-ethylindenyl)}zirconium
 dibromide,
 rac-dimethyl-silylene-bis{1-(2,7-dimethyl-4-i-propyl-1-indenyl)zirconiumdi
 methyl,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-i-propyl-1-indenyl)zirconiummet
 hyl chloride,
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-i-propyl-1-indenyl)zirconium-bi
 s{1-(trifluromethanesulfonate),
 rac-dimethylsilylene-bis{1-(2,7-dimethyl-4-i-propyl-1-indenyl)zirconium-bi
 s{1-(p-phenylsulfinate),
 rac-dimethylsilylene-bis{1-(2-phenyl-4-i-propyl-7-methyl-1-indenyl)zirconi
 um dichloride,
 rac-dimethylsilylene-bis(1,2-dihydroacenaph-thylo(4,5-b)cyclopentadienyl)z
 irconium dichloride, rac-dimethylsilylene-bis(benzo(e)indenyl)zirconium
 chloride, rac-dimethylsilylene-bis{1-(4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2-methyl-4-phenyl-indenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(.alpha.-naphthyl)indenyl})zirconiu
 m dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(.beta.-naphthyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(1-anthracenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(2-anthracenyl)-indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(9-anthracenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(9-phenanthryl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(p-fluorophenyl)indenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(pentafluorophenyl)indenyl}]zirconi
 um dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(p-chlorophenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(m-chlorophenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(o-chlorophenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(o,p-dichlorophenyl)phenyl-1-indeny
 l})zirconium dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(p-bromophenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(p-tolyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(m-tolyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(o-tolyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(o,o'-dimethylphenyl)-1-indenyl})zi
 rconium dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(p-ethylphenyl)indenyl})zirconium
 dichloride, rac-dimethyl
 silylene-bis(1-{2-methyl-4-(p-i-propylphenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(p-benzylphenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(p-biphenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(m-biphenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(p-trimethylsilylene)phenyl)indenyl
 })zirconium dichloride,
 rac-dimethylsilylene-bis(1-{2-methyl-4-(m-trimethylsilylenephenyl)indenyl}
 )zirconium dichloride,
 rac-dimethylsilylene-bis(2-phenyl-4-phenylindenyl)}zirconium dichloride,
 rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconiumdimethyl,
 rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconiummethyl
 chloride, rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 chloride SO.sub.2 Me,
 rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium chloride
 OSO.sub.2 Me,
 rac-dimethylsilylene-bis{1-{2-methyl-4-phenylindenyl)}zirconium
 monochloride mono(trifluoromethanesulfonate),
 rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 di(trifluoromethanesulfonate),
 rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 di-(p-toluene-sulfonate),
 rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 di-(methylsulfonate),
 rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 di(trifluoromethane sulfinate),
 rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 di(trifluoroacetate),
 rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 monochloride (n-butoxide),
 rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 di-(butoxide),
 rac-dimethylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 monochloride (phenoxide),
 rac-methylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride,
 rac-ethylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium dichloride,
 rac-di-(i-propyl)silylene-bis {1-(2-methyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-di-(n-butyl)silylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dicyclohexylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-methylphenylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-diphenylsilylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-di-(p-tolyl)silylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-di-(p-chlorophenyl)silylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylgermylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylstannylene-bis{1-(2-methyl-4-phenylindenyl)}zirconium
 dichloride, rac-dimethylsilylene-bis{1-(2-ethyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(.alpha.-naphthyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(.beta.-naphthyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(2-methyl-1-naphthyl)indenyl})ziconi
 um dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(5-acenaphthyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(9-anthracenyl)indenyl})ziconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(9-phenanthryl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(o-methylphenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(m-methylphenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(p-methylphenyl)indenylenyl})zirconi
 um dicholoride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(2,3-dimethylphenyl)indenyl})zirconi
 um dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(2,4-dimethylphenyl)indenyl})zirconi
 um dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(2,5-dimethylphenyl)indenyl})zirconi
 um dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(2,4,6-trimethylphenyl)indenyl})zirc
 onium dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(o-chlorophenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(m-chlorophenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(p-chlorophenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(2,3-dichlorophenyl)indenyl})zirconi
 um dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(2,6-dichlorophenyl)indenyl})zirconi
 um dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(3,5-dichlorophenyl)indenyl})zirconi
 um dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(2-bromophenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis-(1-{2-ethyl-4-(3-bromophenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(4-bromophenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(4-biphenylyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-ethyl-4-(4-trimethylsilylenephenyl)indenyl})
 zirconium dichloride,
 rac-dimethylsilylene-bis{1-(2-n-propyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-n-propyl-4-(.alpha.-naphthyl)indenyl})zircon
 ium dichloride,
 rac-dimethylsilylene-bis(1-{2-n-propyl-4-(.beta.-naphthyl)indenyl})zirconi
 um dichloride,
 rac-dimethylsilylene-bis(1-{2-n-propyl-4-(2-methyl-1-naphthyl)indenyl})zir
 conium dichloride,
 rac-dimethylsilylene-bis(1-{2-n-propyl-4-(5-acenaphthyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-n-propyl-4-(9-anthracenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-n-propyl-4-(9-phenanthryl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2-i-propyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-i-propyl-4-(.alpha.-naphthyl)indenyl})zircon
 ium dichloride,
 rac-dimethylsilylene-bis(1-{2-i-propyl-4-(.beta.-naphthyl)indenyl})zirconi
 um dichloride,
 rac-dimethylsilylene-bis(1-{2-i-propyl-4-(2-methyl-1-naphthyl)indenyl})zir
 conium dichloride,
 rac-dimethylsilylene-bis(1-{2-i-propyl-4-(5-acenaphthyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-i-propyl-4-(9-anthracenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-i-propyl-4-(9-phenanthryl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2-s-butyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-s-butyl-4-(.alpha.-naphthyl)indenyl)}zirconi
 um dichloride,
 rac-dimethylsilylene-bis(1-{2-s-butyl-4-(.beta.-naphthyl)indenyl})zirconiu
 m dichloride,
 rac-dimethylsilylene-bis(1-{2-s-butyl-4-(8-methyl-9-naphthyl)indenyl})zirc
 onium dichloride,
 rac-dimethylsilylene-bis(1-{2-s-butyl-4-(5-acenaphthyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-s-butyl-4-(9-anthracenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-s-butyl-4-(9-phenanthryl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis{1-(2-n-pentyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-n-pentyl-4-(.alpha.-naphthyl)indenyl})zircon
 ium dichloride,
 rac-dimethylsilylene-bis-{1-(2-n-butyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis-(1-{2-n-butyl-4-(.alpha.-naphthyl)indenyl})zircon
 ium dichloride,
 rac-dimethylsilylene-bis-(1-{2-n-butyl-4-(.beta.-naphthyl)indenyl})zirconi
 um dichloride,
 rac-dimethylsilylene-bis(1-{2-n-butyl-4-(2-methyl-1-naphthyl)indenyl})zirc
 onium dichloride,
 rac-dimethylsilylene-bis(1-{2-n-butyl-4-(5-acenaphthyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-n-butyl-4-(9-anthracenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-n-butyl-4-(9-phenanthryl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-i-butyl-4-(9-phenanthryl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(-1-{2-i-butyl-4-(.alpha.-naphthyl)indenyl})zircon
 ium dichloride,
 rac-dimethylsilylene-bis(1-{2-i-butyl-4-(.beta.-naphthyl)indenyl})zirconiu
 m dichloride,
 rac-dimethylsilylene-bis(1-{2-i-butyl-4-(2-methyl-1-naphthyl)indenyl})zirc
 onium dichloride,
 rac-dimethylsilylene-bis(1-{2-i-butyl-4-(5-acenaphthyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-i-butyl-4-(9-anthracenyl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis(1-{2-i-butyl-4-(9-phenanthryl)indenyl})zirconium
 dichloride,
 rac-dimethylsilylene-bis-{1-(2-neopentyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis-(1-{2-neopentyl-4-(.alpha.-naphthyl)indenyl})zirc
 onium dichloride,
 rac-dimethylsilylene-bis{1-(2-n-hexyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylsilylene-bis-(1-{2-n-hexyl-4-(.alpha.-naphthyl)indenyl})zircon
 ium dichloride,
 rac-methylphenylsilylene-bis{1-(2-ethyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-methylphenylsilylene-bis-(1-{2-ethyl-4-(.alpha.-naphthyl)indenyl})zirc
 onium dichloride,
 rac-methylphenylsilylene-bis(1-{2-ethyl-4-(9-anthracenyl)indenyl})zirconiu
 m dichloride,
 rac-methylphenylsilylene-bis(1-{2-ethyl-4-(9-phenanthryl)indenyl})zirconiu
 m dichloride,
 rac-diphenylsilylene-bis{1-(2-ethyl-4-phenylindenyl)}zirconium dichloride,
 rac-diphenylsilylene-bis(1-{2-ethyl-4-(.alpha.-naphthyl)indenyl})zirconium
 dichloride,
 rac-diphenylsilylene-bis(1-{2-ethyl-4-(9-anthracenyl)indenyl})zirconium
 dichloride,
 rac-diphenylsilylene-bis(1-{2-ethyl-4-(9-phenanthryl)indenyl})zirconium
 dichloride,
 rac-diphenylsilylene-bis(1-{2-ethyl-4-(4-biphenylyl)indenyl})zirconium
 dichloride, rac-methylene-bis {1-(2-ethyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-methylene-bis(1-{2-ethyl-4-.alpha.-naphthyl)indenyl})zirconium
 dichloride, rac-ethylene-bis{1-(2-ethyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-ethylene-bis(1-{2-ethyl-4-(.alpha.-naphthyl)indenyl})zirconium
 dichloride,
 rac-ethylene-bis(1-{2-n-propyl-4-(.alpha.-naphthyl)indenyl})zirconium
 dichloride, rac-dimethylgermylene-bis
 {1-(2-ethyl-4-phenylindenyl)}zirconium dichloride,
 rac-dimethylgermylene-bis(-1-{2-ethyl-4-(.alpha.-naphthyl)indenyl})zirconi
 um dichloride,
 rac-dimethylgermylene-bis{1-(2-n-propyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylstannylene-bis{1-(2-ethyl-4-phenylindenyl)}zirconium
 dichloride,
 rac-dimethylstannylene-bis-(1-{2-ethyl-4-(.alpha.-naphthyl)indenyl})zircon
 ium dichloride,
 rac-dimethylstannylene-bis(1-{2-n-ethyl-4-(9-phenanthryl)indenyl})zirconiu
 m dichloride,
 rac-dimethylstannylene-bis{1-{2-n-propyl-4-phenylindenyl)}zirconium
 dichloride and so on.
 Further, there may be exemplified transition metal compounds in which the
 zirconium atom in the above-mentioned transition metal compounds is
 replaced with titanium atom, hafnium atom, vanadium atom, niobium atom,
 tantalum atom, chromium atom, molybdenum atom or wolfram atom.
 In general, the transition metal compound (a) is incorporated as a
 component for the catalyst for polymerizing olefins in the form of racemic
 body, while an R-type or S-type compound (a) may also be utilized.
 According to the present invention, a plurality of the above-mentioned
 transition metal compounds (a) can be used in combination.
 According to the present invention, at least one compound selected from the
 group consisting of (b) organoaluminum compounds, (c) organoaluminum
 oxy-compounds and (d) ionizing ionic compounds, as activator capable of
 activating the above-mentioned transition metal compounds (a).
 The organoaluminum compound (b) is represented, for example, by the
 following formula (3):
EQU (R.sup.1).sub.n AlX.sub.3-n (3)
 in which R.sup.1 is a hydrocarbon group having 1-12 carbon atoms, X denotes
 a halogen atom or hydrogen atom and n is an integer of 1-3.
 In the formula (3), R.sup.1 represents a hydrocarbon group having 1-12
 carbon atoms, such as alkyl, cycloalkyl or aryl and, concretely, it stands
 for methyl, ethyl, n-propyl, isopropyl, isobutyl, pentyl, hexyl, octyl,
 cyclopentyl, cyclohexyl, phenyl or tolyl.
 Concrete examples of such an organoaluminum compound (b) include
 trialkylaluminums, such as trimethylaluminum, triethylaluminum,
 triisopropylaluminum, triisobutylaluminum, trioctylaluminum and
 tri-2-ethylhexylaluminum; alkenylaluminums, such as isoprenylaluminum and
 so on; dialkylaluminum halides, such as dimethylaluminum chloride,
 diethylaluminum chloride, diisopropylaluminum chloride, diisobutylaluminum
 chloride and dimethylalumunim bromide; alkylaluminum sesquihalides, such
 as methylaluminum sesquichloride, ethylaluminum sesquichloride,
 isopropylaluminum sesquichloride, butylaluminum sesquichloride and
 ethylaluminum sesquibromide; alkylaluminum dihalides, such as
 methylaluminum dichloride, ethylaluminum dichloride, isopropylaluminum
 dichloride and ethylaluminum dibromide; and alkylaluminum hydrides, such
 as diethylaluminum hydride and diisobutylaluminum hydride.
 It is permissible to use, as the organoaluminum compound (b), also the
 compounds represented by the following formula (4):
EQU (R.sup.1).sub.n AlY.sub.3-n (4)
 in which R.sup.1 is the same as R.sup.1 in the formula (3), Y denotes a
 group of --OR.sup.2, --OSi(R.sup.3).sub.3, --OAl(R.sup.4).sub.2,
 --N(R.sup.5).sub.2, --Si(R.sup.6).sub.3 or --N(R.sup.7)Al(R.sup.8).sub.2
 and n is a number of 1-2, wherein R.sup.2, R.sup.3, R.sup.4 and R.sup.8
 denote each methyl, ethyl, isopropyl, isobutyl, cyclohexyl or phenyl,
 R.sup.5 denotes hydrogen atom, methyl, ethyl, isopropyl, phenyl or
 trimethylsilyl and R.sup.6 and R.sup.7 represent each methyl, ethyl or the
 like.
 Concretely, there may be enumerated the following compounds:
 1) Compounds represented by (R.sup.1).sub.n Al(OR.sup.2).sub.3-n, for
 example, dimethylaluminum methoxide, diethylaluminum ethoxide and
 diisobutylaluminum methoxide
 2) Compounds represented by (R.sup.1).sub.n Al{OSi(R.sup.3).sub.3
 }.sub.3-n, for example, Et.sub.2 Al(OSiMe.sub.3), (iso-Bu).sub.2
 Al(OSiMe.sub.3) and (iso-Bu).sub.2 Al(OSiEt.sub.3)
 3) Comopunds represented by (R.sup.1).sub.n Al{OAl(R.sup.4).sub.2
 }.sub.3-n, for example, Et.sub.2 AlOAlEt.sub.2 and (iso-Bu).sub.2
 AlOAl(iso-Bu).sub.2
 4) Compounds represented by (R.sup.1).sub.n Al{N(R.sup.5).sub.2 }.sub.3-n,
 for example, Me.sub.2 AlNEt.sub.2, Et.sub.2 AlNHMe, Me.sub.2 AlNHEt,
 Et.sub.2 AlN(SiMe.sub.3).sub.2 and (iso-Bu).sub.2 AlN(SiMe.sub.3).sub.2
 5) Compounds represented by (R.sup.1).sub.n Al{Si(R.sup.6).sub.3 }.sub.3-n,
 for example, (iso-Bu).sub.2 AlSiMe.sub.3 and the like
 6) Compounds represented by (R.sup.1).sub.n Al{N(R.sup.7)Al(R.sup.8).sub.2
 }.sub.3-n, for example, Et.sub.2 AlN(Me)AlEt.sub.2 and (iso-Bu).sub.2
 AlN(Et)Al(iso-Bu).sub.2
 In the above, Me represents methyl group, Et denotes ethyl group and Bu
 represents butyl group.
 Among them, compounds represented by the formulae (R.sup.1).sub.3 Al,
 (R.sup.1).sub.n Al(OR.sup.2).sub.3-n and (R.sup.1).sub.n
 Al{OAl(R.sup.4).sub.2 }.sub.3-n are preferred, wherein special preference
 is given to those compounds in which R denotes an iso-alkyl and n is 2. It
 is permissible to use them in a combination.
 The organoaluminum compounds (c) may be known aluminoxanes soluble in
 benzene or may be organoaluminum oxy-compounds insoluble in benzene
 disclosed in Japanese Patent Kokai Hei-2-276807 A.
 The aluminoxane can be prepared, for example, by the methods given below:
 (1) A method in which an organoaluminum compound, such as trialkylaluminum,
 is added to a suspension of a salt containing adsorbed moisture or water
 of cristallization, such as hydrated salt of magnesium chloride, copper
 sulfate, aluminum sulfate, nickel sulfate or cerous chloride, in a
 hydrocarbon solvent, to cause a reaction.
 (2) A method in which an organoaluminum compound, such as trialkylaluminum,
 is reacted dierectly with water, ice or steam in a medium, such as
 benzene, toluene, ethyl ether or tetrahydrofuran.
 (3) A method in which an organoaluminum compound, such as trialkylaluminum,
 is reacted with an organotin oxide, such as dimethyltin oxide or
 dibutyltin oxide, in a medium, such as decane, benzene or toluene.
 These aluminoxanes may contain a small amount of organometallic
 component(s). They may be re-dissolved in a solvent, after the reaction
 solvent or the unreacted organoaluminum compound has been removed from the
 recovered aluminoxane solution by distillation.
 As the organoaluminum compound to be used on the preparation of the
 aluminoxane, concretely, those exemplified above for the organoaluminum
 compound (b) may be enumerated. Among them, special preference is given to
 trialkylaluminums and tricycloalkylaluminums.
 As the solvent used in the preparation of the aluminoxane, there may be
 exemplified aromatic hydrocarbons, such as benzene, toluene, xylene,
 cumene and cymene; aliphatic hydrocarbons, such as pentane, hexane,
 heptane, octane, decane, dodecane, hexadecane and octadecane; alicyclic
 hydrocarbons, such as cyclopentane, cyclohexane, cyclooctane and
 methylcyclopentane; petroleum cut fractions, such as gasoline, kerosene
 and gas oil; and halogenated hydrocarbons, especially those chlorinated or
 brominated products of the aromatic, aliphatic and alicyclic hydrocarbons
 given above. Other solvents, for example, ethers, such as ethyl ether and
 tertahydrofuran may also be used. Among these solvents, especially
 aromatic hydrocarbons are preferred.
 The organoaluminum oxy-compounds to be used according to the present
 invention is insoluble or difficultly soluble in benzene and have an Al
 component soluble in benzene at 60.degree. C. of 10% or less, preferably
 5% or less and especially preferably 2% or less, calculated as aluminum
 atom.
 The solubility of the organoaluminum compound is determined by suspending
 such an amount of the organoaluminum compound as corresponding to 100 mg
 of aluminum atom in 100 ml of benzene and mixing the resulting suspension
 at 60.degree. C. with stirring for 6 hours, before subjecting the
 suspension to hot filteration at 60.degree. C. through a G-5 glass filter
 with four times washings of the solid residue retained on the glass filter
 with each 50 ml of benzene of 60.degree. C. and, then, determining the
 amount of aluminum atom in the total filtrate (X mmol corresponding to X
 %).
 The ionizing ionic compound (d) serves for reacting with the transition
 metal compound (a) represented by the formula (1) to form an ion pair. For
 the ionizing ionic compound (d), there may be exemplified Lewis acids,
 ionic compounds and carboranes as disclosed in, for example, Japanese
 Patent Kokais Hei-1-501950 A, Hei-1-502036 A, Hei-3-179005 A, Hei-3-179006
 A, Hei-3-207703 A, Hei-3-207704 A and U.S. Pat. No. 5,321,106.
 As the Lewis acid, there may be enumerated, for example, triphenylboron,
 tris(4-fluorophenyl)boron, tris(p-tolyl)boron, tris(o-tolyl)boron,
 tris(3,5-dimethylphenyl)boron, tris(pentafluorophenyl)boron, MgCl.sub.2,
 Al.sub.2 O.sub.3 and SiO.sub.2 --Al.sub.2 O.sub.3.
 As the ionic compound, there may be enumerated for example,
 triphenylcarbenium tetrakis(pentafluorophenyl)borate, tri-n-butylammonium
 tetrakis(pentafluorophenyl)borate, N,N-dimethylammonium
 tetrakis(pentafluorophenyl)borate and ferrocenium
 tetra(pentafluorophenyl)boron.
 As the carboranes, there may be enumerated, for example, dodecaborane,
 1-carbaundecaborane, bis-n-butylammonium(1-carbedodeca)borate,
 tri-n-butylammonium-(7,8-dicarbaundeca)borate, and
 tri-n-butylammonium-(tridecahydrido-7-carbaundeca)borate.
 These ionizing ionic compounds (d) may be used alone or in a combination of
 two or more of them. It is possible to use, as the activator for
 activating the transition metal compound (a), the above-mentioned
 components (b), (c) and (d) in a combination.
 The metallocene catalyst can be prepared by mixing at least one activator
 compound selected from the group consisting of the above-mentioned
 compounds (b) to (d), together with the transition metal compound (a) in
 an inert hydrocarbon solvent or olefin solvent.
 As the inert hydrocarbon solvent to be used in the preparation of the
 catalyst based on metallocene, there may be exemplified aliphatic
 hydrocarbons, such as propane, butane, pentane, hexane, heptane, octane,
 decane, dodecane and hexadecane; alicyclic hydrocarbons, such as
 cyclopentane, cyclohexane, methylcyclopentane, and cyclooctane; aromatic
 hydrocarbons, such as benzene, toluene and xylene; halogenated
 hydrocarbons, such as ethylene chloride, chlorobenzene and
 dichloromethane; petroleum cut fractions, such as gasoline, kerosene and
 gas oil; and mixture of them.
 Upon the preparation of the metallocene from these components, the
 transition metal compounds may favorably be used usually at a
 concentration of about 10.sup.-8 -10.sup.-1 mole/liter (of polymerization
 volume), preferably 10.sup.-7 -5.times.10.sup.-2 mole/liter.
 When the component (b) and/or (c) is used as the activator component, the
 component (b) and/or (c) may favorably be used usually in an amount of
 10-10,000, preferably 20-5,000 in the atomic ratio of aluminum to the
 transition metal of the tansition metal compound (a) {i.e. Al/transition
 metal}. When the organoaluminum compound (b) and the organoaluminum
 oxy-compound (c) are used concurrently, it is favorable to use them in
 such an amount that the atomic ratio (Al-1/Al-2) of aluminum atom (Al-2)
 in the component (b) to the aluminum atom (Al-2) in the component (c) will
 be in the range of 0.02-3, preferably 0.05-1.5.
 When the ionizing ionic compound (d) is used, it may be used usually in
 such an amount that the mole ratio of the transition metal (a) to the
 component (d), namely, (a)/(d) will be in the range of 0.01-10, preferably
 0.1-5.
 These catalyst components may either be mixed in the polymerization reactor
 or be added to the polymerization reactor in a preliminarily mixed blend.
 When these components are blended preliminarily, the monomers may be
 contacted therewith usually at a temperature of -50 to +150.degree. C.,
 preferably -20 to +120.degree. C., for a duration of 1 minute to 50 hours,
 preferably 5 minutes to 25 hours. In the case of mixing contact, the
 mixing temperature may be varied.
 The metallocene catalyst may be a solid catalyst having either one or all
 of the above-mentioned components (a) to (d) supported on a granular or
 fine particulate solid material (carrier).
 The carrier may be of organic or inorganic material. For the inorganic
 carrier, porous oxides are used preferably, for example, SiO.sub.2 and
 Al.sub.2 O.sub.3. For the organic carrier, a polymer resin, such as
 homopolymer or copolymer constituted mainly of an .alpha.-olefin having
 2-14 carbon atoms, such as ethylene, propylene, 1-butene or
 4-methyl-1-pentene, and homo- and copolymer resins constituted mainly of
 vinylcyclohexane and/or styrene may be used.
 The metallocene catalyst may also be used after a prepolymer catalyst has
 been formed by causing each of the catalyst components to be introduced
 into a prepolymerization of an olefin. For the .alpha.-olefin to be
 subjected to such prepolymerization, there may be employed, for example,
 propylene, ethylene and 1-butene, wherein they may be used in combination
 with other olefins.
 On preparing the metallocene-based catalyst, component(s) useful for
 polymerization of olefin other than the catalyst components mentioned
 above can be incorporated, for example, water as a catalyst component.
 The ethylene/.alpha.-olefin random copolymer (B) and the the
 propylene/ethylene/1-butene random copolymer (C) can be produced by
 co-polymerizing ethylene with the .alpha.-olefin, on the one hand, and
 propylene with 1-butene and ethylene, on the other hand respectively, in
 the presence of the above-mentioned metallocene catalyst.
 The polymerization can be realized either in a liquid phase polymerization,
 such as suspension polymerization and solution polymerization, or in a gas
 phase polymerization. In a liquid phase polymerization, the same inert
 solvent used in the preparation of the catalyst can be used and, further,
 .alpha.-olefins, such as propylene and so on, may also be employed.
 When the polymerization is carried out in a suspension polymerization, it
 is favorable to effect the polymerization at a temperature of -50 to
 +100.degree. C., preferably 0 to 90.degree. C., whereas when the
 polymerization is carried out in a solution polymerization, it is
 favorable to choose the polymerization temperature in the range of
 0-250.degree. C., preferably 20-200.degree. C. When a gas phase
 polymerization is to be employed, the polymerization may favorably be
 carried out at a temperature of 0-120.degree. C., preferably
 20-100.degree. C., under a pressure in the range from normal pressure to
 9.8 MPa (100 kgf/cm.sup.2, gauge), prefrably from normal pressure to 4.9
 MPa (50 kgf/cm.sup.2, gauge).
 The polymerization can be effected either in a batch-wise process, in a
 semi-continuous process or in a continuous process. It is possible to
 effect the polymerization in two or more successive steps to be performed
 each under a different condition. The molecular weight of the resulting
 copolymer can be adjusted by, for example, effecting the polymerization
 under incorporation of hydrogen gas or under alteration of condition of
 temperature or pressure.
 The polypropylene resin composition according to the present invention
 comprises the polypropylene resin (A) in an amount of 50-95 parts by
 weight, the ethylene/.alpha.-olefin random copolymer (B) in an amount of
 3-40 parts by weight and the propylene/ethylene/1-butene random copolymer
 in an amount of 2-20 parts by weight and preferably the polypropylene
 resin (A) in an amount of 60-92 parts by weight, the
 ethylene/.alpha.-olefin random copolymer (B) in an amount of 5-30 parts by
 weight and the propylene/ethylene/1-butene random copolymer (C) in an
 amount of 3-10 parts by weight, wherein the total amount of these three
 components (A), (B) and (C) sums up to 100 parts by weight.
 The polypropylene resin composition according to the present invention may
 contain in addition to the polypropylene (A), the ethylene/.alpha.-olefin
 random copolymer (B) and the propylene/ethylene/1-butene random copolymer
 (C) other ingredient(s), such as additives and other polymer(s), within
 the limit not obstructing the inventive advantages of the resin
 composition according to the present invention.
 As the additives, there may be incorporated weather resistant agent, heat
 stabilizer, antifogging agent, antiblocking agent, slipping agent,
 lubricant, antistatic agent, fire retardant, pigments, dyestuffs and
 filler.
 The polypropylene resin composition according to the present invention can
 be produced by a method known in general, for example, by melt-kneading
 the polypropylene (A), the ethylene/.alpha.-olefin random copolymer (B)
 and the propylene/ethylene/1-butene random copolymer (C) as well as other
 ingredient(s) to be incorporated optionally.
 For example, the polypropylene resin composition according to the present
 invention can be prepared by charging an adequate mixing device, such as
 Henschel mixer, V-shaped mixer, tumbler mixer or ribbon blender, with the
 above-mentioned components and ingredients all at once or successively and
 mixing them therein, followed by melt-kneading the resulting mixture on,
 for example, monoaxial or multiaxial extruder, kneader, Bumbury's mixer.
 The polypropylene resin composition according to the present invention may
 favorably have an MFR, determined according to ASTM D-1238 at 230.degree.
 C. under a load of 2.16 kg, in the range of 1 to 100 g/10 min., in
 particular, 1 to 50 g/10 min.
 The melting point (determined by DSC method) of the polypropylene resin
 composition according to the present invention may favorably be in the
 range of 100-167.degree. C., in particular 120-167.degree. C.
 The polypropylene resin composition can be processed into non-stretched
 films by extrusion molding known per se. The non-stretched films obtained
 by extrusion molding are superior in the transparency, in the impact
 resistence, in the low temperature heat-sealability and in the
 heat-sealing strength, so that they are suitable for using as monolayer
 non-stretched films.
 The non-stretched film according to the present invention is produced by
 subjecting the polypropylene resin composition described above to a
 film-forming by extrusion molding.
 The thickness of the non-stretched film according to the present invention
 may usually be in the range of 10-100 .mu.m, preferably 20-80 .mu.m,
 though there may be variations depending on each specific use.
 The non-stretched film according to the present invention can be utilized
 in packaging field, for example, for packaging foods including perishable
 foods, such as vegetables and fish meals; dry foods, such as snack and dry
 noodle; and wetty foods, such as soup and pickles; for packaging medical
 products including medicaments, such as tablet, powder, solution etc., and
 medical utensils; for packaging electric and electronic products including
 instrumental parts, cassettes and so on.
 The extrusion molding for producing the non-stretched film according to the
 present invention may be realized by proper selection of the apparatus and
 processing conditions among those known previously for extrusion-molding a
 polypropylene resin or polypropylene resin composition.
 As described above, the polypropylene resin composition according to the
 present invention can be processed into a non-stretched film which is
 superior in the transparency, impact resistance, heat sealability at low
 tmperature and heat sealing strength, since it has specific components,
 namely, the polypropylene resin (A), the ethylene/.alpha.-olefin random
 copolymer (B) and the propylene/ethylene/1-butene random copolymer (C) in
 a special proportion.

THE BEST MODE FOR EMBODYING THE INVENTION
 Below, the present invention will further be described by way of Examples
 and Comparative Example, wherein these Examples are not given for
 restricting the present invention in any respect.
 The values of evaluations given in Examples and Comparative Example are
 based on the following schemes:
 (1) Heat-Sealing Strength:
 The heat-sealing strength (peeling strength) was determined in accordance
 with the method prescribed in JIS Z 1707 under the conditions:

Sealing pressure 0.2 MPa
 Duration of sealing operation 1 second
 Peeling speed 300 mm/min.
 (2) Impact Resistance:
 The film impact strength was observed as a parameter of the impact
 resistance and determined in accordance with the method prescribed in JIS
 P8134. The testing machine has a capacity of 30 kg/cm.cm and an impact
 head of 1/2 inch .phi..
 (3) Transparency:
 The haze was observed as a parameter of the transparency in accordance with
 the method prescribed in ASTM D 1003.
 (4) Gloss:
 The gloss was determined in accordance with the method prescribed in ASTM D
 523.
 Production Example 1
 Production of Ethylene/.alpha.-olefin Random Copolymer (B)
 An ethylene/1-butene random copolymer was produced using a metallocene
 catalyst. Thus, a two liter autoclave replaced sufficiently by nitrogen
 gas was charged with 950 ml of hexane and 50 g of 1-butene, whereto was
 added 1 mmol of triisobutylaluminum. The autoclave was heated at
 70.degree. C. and was supplied with ethylene until a total pressure of 0.7
 MPa (7 kgf/cm.sup.2, gauge) was reached, whereto were added 0.30 mmol of
 methylaluminoxane and 0.001 mmol, calculated as Zr atom, of
 rac-dimethylsilylene-bis(1-{2-n-propyl-4-(9-phenanthryl)indenyl})zirconium
 dichloride, whereupon ethylene was replenished thereto succesively while
 maintaining the total pressure of 0.7 MPa (7 kgf/cm.sup.2, gauge) in order
 to proceed the polymerization for 30 minutes.
 After the polymerization, the internal gas was evacuated and the resulting
 polymer was recovered in a plentiful amount of methanol, whereupon the
 polymer was dried under a reduced pressure at 110.degree. C. for 12 hours.
 The resulting polymer {a branched long chain ethylene/1-butene random
 copolymer (B-1)} amounted 28.0 g and the polymerization activity was
 calculated to be 56 kg of polymer per mmol of Zr per hour.
 The chemical composition and the material properties of this product were
 as follows:
 (1) Chemical Composition:
 Content of ethylene unit =89.0 mole %
 Content of 1-butene unit =11.0 mole %
 (2) MFR (ASTM D-1238, 190.degree. C., 2.16 kg load)=3.6 g/10 min.
 (3) Molecular weight distribution (Mw/Mn) by GPC=2.0
 (4) Density=0.885 g/cm.sup.3
 (5) B-value=1.1
 (6) Intrinsic viscosity [.eta.]=1.48 dl/g
 (7) g.eta.*=0.89
 Production Example 2
 The procedures of Production Example 1 were pursued except that
 bis(1,3-dimethylcyclopentadienyl)zirconium was used in the place of
 rac-dimethylsilylene-bis(1-{2-n-propyl-4-(9-phenathryl)indenyl})zirconium
 dichloride, whereby a linear chain ethylene/1-butene random copolymer
 (B-2) was obtained.
 The chemical composition and material property of this polymer product are
 as given below:
 (1) Chemical Composition:
 Content of ethylene unit=89.2 mole %
 Content of 1-butene unit=10.8 mole %
 (2) MFR (ASTM D-1238, 190.degree. C., 2.16 kg load)=3.4 g/10 min.
 (3) Molecular weight distribution (Mw/Mn) by GPC=2.0
 (4) Density=0.884 g/cm.sup.3
 (5) B-value=1.0
 (6) Intrinsic viscosity [.eta.]=1.49 dl/g
 (7) g.eta.*=1.00
 Production Example 3
 Production of Propylene/Ethylene/1-butene Random Copolymer (C)
 A propylene/ethylene/1-butene random copolymer was produced using a
 metallocene catalyst. Thus, a two liter autoclave replaced sufficiently by
 nitrogen gas was charged with 950 ml of hexane and 75 g of 1-butene,
 whereto was added 1 mmol of triisobutylaluminum. The autoclave was heated
 at 70.degree. C. and was supplied with propylene and ethylene until a
 total pressure of 0.7 MPa (7 kgf/cm.sup.2, gauge) was reached whereto were
 added 0.30 mmol of methylaluminoxane and 0.001 mmol, calculated as Zr
 atom, of
 rac-dimethylsilylene-bis(1-{2-n-propyl-4-(9-phenanthryl)indenyl})zirconium
 dichloride, whereupon propylene and ethylene were replenished succesively
 so as to settle the mole ratio of the supplied amount of propylene to the
 supplied amount of ethylene (propylene/ethylene) at 95/5, while
 maintaining the total pressure of 0.7 MPa (7 kgf/cm.sup.2, gauge) in order
 to proceed polymerization for 30 minutes.
 After the polymerization, the internal gas was evacuated and the resulting
 polymer was recovered in a plentiful amount of methanol, whereupon the
 polymer was dried under a reduced pressure at 110.degree. C. for 12 hours.
 The resulting polymer (a propylene/ethylene/1-butene random copolymer)
 amounted 28.0 g and the polymerization activity was calculated to be 56 kg
 of polymer per mmol of Zr per hour.
 The chemical composition and the material properties of this product were
 as follows:
 (1) Chemical Composition:
 Content of propylene unit=68.5 mole %
 Content of ethylene unit=10.2 mole %
 Content of 1-butene unit=21.3 mole %
 (2) MFR (ASTM D-1238, 230.degree. C., 2.16 kg load)=4.4 g/10 min.
 (3) Molecular weight distribution (Mw/Mn) by GPC=2.3
 (4) Triple chain structure constituted of head-to-tail-coupled propylene
 unit: present
 (5) Triple chain structure constituted of head-to-tail-coupled propylene
 unit and 1-butene unit containing propylene unit in the 2nd site: present
 EXAMPLE 1
 A propylene/ethylene random copolymer (A) containing 96.8 mole % of
 propylene unit and 3.2 mole % and having an MFR (ASTM D-1238, 230.degree.
 C., 2.16 kg load) of 6.9 g/10 min., the branched long chain
 ethylene/1-butene random copolymer (B-1) obtained in Production Example 1
 and the propylene/ethylene/1-butene random copolymer (C) obtained in
 Production Example 2 were blended in a mixer in a proportion given in
 Table 1 and the resulting mixture was melt-kneaded on an extruder at a
 temperature of 210.degree. C., whereupon the kneaded mass was extruded
 into a form of strand. The resulting extruded polypropylene resin
 composition in the form of strand was cut in an aqueous medium to prepare
 a pelletized product of each resin composition.
 This pelletized product was extruded from a die with a thin slit on an
 extruder (monoaxial, 40 mm .phi., L/D=26, cylinder temperature=210.degree.
 C.) into a monolayer non-stretched film having a thickness of 50 .mu.m.
 The evaluation results of the so-obtained monolayer non-stretched film are
 summarized in Table 1.
 EXAMPLES 2 AND 3
 The procedures of Example 1 were repeated except that the polypropylene
 resin composition as given in Table 1 was used. The results are given in
 Table 1.
 EXAMPLE 4
 The procedures of Example 1 were repeated except that the linear chain
 ethylene/1-butene random copolymer (B-2) obtained in Production Example 2
 was used in the place of the branched long chain ethylene/1-butene random
 copolymer (B-1) obtained in Production Example 1 to produce a monolayer
 non-stretched film. The evaluation results of the resulting non-stretched
 film are given in Table 1.
 Comparative Example 1
 The procedures of Example 1 were repeated except that the
 propylene/ethylene/1-butene random copolymer (C) was not used and the
 blended proportion of the ethylene/1-butene random copolymer (B-1) was
 changed to 20 parts by weight to produce a monolayer non-stretched film
 having a thickness of 50 .mu.m. The evaluation results of the so-obtained
 monolayer non-stretched film are summarized in Table 1.
 TABLE 1
 Com-
 Ex- Ex- Ex- Ex- par.
 ample ample ample ample Ex.
 1 2 3 4 1
 Proportion (phr .sup.1))
 (A) Random PP .sup.2) 80 80 85 80 80
 (B-1) EBR .sup.3) 15 10 7.5 -- 20
 (B-2) EBR .sup.4) -- -- -- 15 --
 (C) PBER .sup.5) 5 10 7.5 5 --
 Material Property
 Haze (%) 1.5 1.6 1.3 1.7 2.3
 Gloss (%) 117 118 119 115 105
 Film Impact (KJ/m)
 at 5.degree. C. 38 29 22 40 32
 at -10.degree. C. 19 12 8 20 14
 Heat Sealabiliy
 (N/15 mm) at
 130.degree. C. 0.2 1.1 0.5 0.2 0.5
 140.degree. C. 1.4 3.5 2.0 1.4 1.4
 150.degree. C. 8.6 12.3 7.5 8.8 7.2
 160.degree. C. 22.4 24.2 19.3 21.2 12.4
 170.degree. C. 24.4 25.5 26.4 23.5 19.9
 180.degree. C. 25.0 -- -- 25.2 21.4
 190.degree. C. 25.4 -- -- 25.5 20.7
 200.degree. C. 26.4 -- -- 25.8 22.1
 Notes:
 .sup.1) Parts by weight in hundred rate
 .sup.2) Propylene/ethylene random copolymer resin (A)
 .sup.3) Branched long chain ethylene/1-butene random copolymer (B-1) of
 Production Example 1
 .sup.4) Linear chain etylene/1-butene random copolymer (B-2) of Production
 Example 2
 .sup.5) Propylene/ethylene/1-butene random copolymer (C) of Production
 Example 3