Propylene homopolymer

A propylene homopolymer, obtained by the polymerization of a propylene in the presence of a catalyst comprising the following components (A), (B) and (C), having a melt flow rate (MFR) determined at a temperature of 230.degree. C. under a load of 2.16 kg of from 0.1 to 20 g/10 min., a 23.degree. C. a xylene-soluble component content of not more than 6% by weight and an isoblock content [IB] of at least 3 mol % as determined by the following equation (1) from Pmmmr, Pmmrr and Pmrrm, which are absorption intensities attributed to isoblock chain in xylene-insoluble component by .sup.13 C-NMR spectrum:

• [IB]=[Pmmmr]+[Pmmrr]+[Pmrrm] (1)
• wherein [Pmmmr], [Pmmrr] and [Pmrrm] are the relative intensity ratio (mol %) of Pmmmr, Pmmrr and Pmrrm, respectively, which are absorption intensities attributed to isoblock chain:
• (A) A solid catalyst component prepared from the following components (a) to (d):
• (a) A magnesium compound represented by the following general formulae:
• Mg(OR.sup.1).sub.2
• wherein R.sup.1 represents a C.sub.1-4 alkyl group or an aryl group;
• (b) An aluminum compound represented by the following general formulae:
• Al(OR.sup.2).sub.m X.sup.1.sub.3-m
• wherein R.sup.2 represents a C.sub.1-4 alkyl group or an aryl group;
• X.sup.1 represents a halogen atom;
• and
• m represents a real number of from at least 0 to not more than 3;
• or
• R.sup.3.sub.n AlX.sup.2.sub.3-n
• wherein R.sup.3 represents a C.sub.1-4 alkyl group;
• X.sup.2 represents a hydrogen atom or halogen atom;
• and
• n represents a real number of from more than 0 to not more than 3;
• (c) A titanium compound represented by the following general formula:
• Ti(OR.sup.4).sub.p X.sup.3.sub.4-p
• wherein R.sup.4 represents a C.sub.1-4 alkyl group;
• X.sup.3 represents a halogen atom;
• and p represents 0 or an integer of from 1 to 3;
• and
• (d) A diester of aromatic dicarboxylic acid;
• (B) An organic aluminum compound represented by the following general formula:
• R.sup.5.sub.q AlY.sub.3-q
• wherein R.sup.5 represents a C.sub.1-4 alkyl group;
• Y represents any one of hydrogen atom, chlorine atom, bromine atom and iodine atom;
• and q represents a real number of from more than 0 to not more than 3;
• and
• (C) An organic silicon compound represented by the following general formula:
• R.sup.6.sub.r Si(OR.sup.7).sub.4-r
• wherein R.sup.6 's may be the same or different and each represents a C.sub.1-12 alkyl group, a cycloalkyl group, a phenyl group, a vinyl group, an allyl group or an aralkyl group;
• R.sup.7 's may be the same or different and each represents a C.sub.1-4 alkyl group, a cycloalkyl group, a phenyl group, a vinyl group, an allyl group or an aralkyl group;
• and r represents 0 or an integer of from I to 3.