Process for preparing polyolefins

Provided is a process for preparing a polyolefin, characterized by polymerizing at least one .alpha.-olefin in the presence of a catalyst which comprises the combination of: [I] a solid catalyst component comprising a solid substance obtained by contacting the following components (1) through (3) with one another and (4) a titanium compound supported on said solid substance: (1) a magnesium halide, (2) a compound represented by the general formula ##STR1## wherein R.sup.1, R.sup.2 and R.sup.3 are each a hydrocarbon radical having 1 to 24 carbon atoms, an alkoxy group, hydrogen, or a halogen atom, R.sup.4 is a hydrocarbon radical having 1 to 24 carbon atoms and n is 1.ltoreq.n.ltoreq.30, and (3) at least one compound selected from the group consisting of: (a) compounds represented by the general formula ##STR2## wherein R is hydrogen, a halogen atom, or a hydrocarbon radical having 1 to 24 carbon atoms, and r, p and q are integers satisfying the following conditions: 1.ltoreq.r.ltoreq.3, 0.ltoreq.p<6, 0.ltoreq.q<6, 1.ltoreq.r+p+q<6, (b) alkyl phosphites, (c)-(e) oxygen, nitrogen or sulfur-containing heterocyclic carboxylic acid esters, (f) alkyl silanols, (g) alkoxy borohalides, (h) alkyl and/or alkoxy substituted sulfoxides, and (i) N-substituted urethanes [II] an organometallic compound; and [III] a compound represented by the general formula ##STR3## wherein R.sup.1, R.sup.2 and R.sup.3 are each a hydrocarbon radical having 1 to 24 carbon atoms, an alkoxy group, hydrogen, or a halogen atom, R.sup.4 is a hydrocarbon radical having 1 to 24 carbon atoms and n is 1.ltoreq.n.ltoreq.30.

What is claimed is:

1. A process for preparing a polyolefin, characterized by polymerizing at least one .alpha.-olefin in the presence of a catalyst which consists of the combination of:

a solid catalyst component consisting of a solid substance obtained by reacting the following components (1) through (3) with one another and (4) a titanium compound supported on said solid substance:

(1) a magnesium halide,

(2) at least one member selected from the group consisting of vinyltrimethoxysilane, vinyltriethoxysilane, vinyltriphenoxysilane, allyltrimethoxysilane, allyltriethoxysilane and allyltriphenoxysilane, and

(3) at least one compound selected from the group consisting of:

(a) compounds represented by the general formula ##STR13## wherein R is hydrogen, a halogen atom, or a hydrocarbon radical having 1 to 24 carbon atoms, R' is a hydrocarbon radical having 1 to 24 carbon atoms, and r, p and q are integers satisfying the following conditions: 1.ltoreq.r.ltoreq.3, 0.ltoreq.p<6, 0.ltoreq.q<6, 1.ltoreq.r+p+q<6,

(b) compounds represented by the general formula P(OR.sup.5).sub.3 wherein R.sup.5 s, which may be alike or different, are each a hydrocarbon radical having 1 to 24 carbon atoms,

(c) heterocyclic carboxylic acid esters containing oxygen as the hetero-atom;

(d) heterocyclic carboxylic acid esters containing nitrogen as the hetero-atom;

(e) heterocyclic carboxylic acid esters containing sulfur as the hetero-atom.

(f) compounds represented by the general formula R.sup.6.sub.t Si(OH).sub.4-t wherein R.sup.6 is a hydrocarbon radical having 1 to 24 carbon atoms and t is 1.ltoreq.t.ltoreq.3,

(g) compounds represented by the general formula B(OR.sup.7).sub.u X.sub.3-u wherein R.sup.7 is a hydrocarbon radical having 1 to 24 carbon atoms, X is a halogen atom and u is 1.ltoreq.u.ltoreq.3,

(h) compounds represented by the general formula R.sup.8.sub.2 SO.sub.w+1 wherein R.sup.8 s, which may be alike or different, are each a hydrocarbon radical having 1 to 24 carbon atoms or an alkoxy group and w is 0 or 1, and

(i) compounds represented by the general formula R.sup.9 NHCOOR.sup.9 wherein R.sup.9 s, which may be alike or different, are each a hydrocarbon radical having 1 to 24 carbon atoms;

an organoaluminum compound; and

a compound selected from the group consisting of monophenyltrimethoxysilane and monophenyltriethoxysilane,

wherein said solid substance is obtained by a co-pulverization at a temperature of 0-200 degrees C. for a time of 0.5 to 30 hours of said components (1), (2) and (3), wherein the ratio of said component (1) to said component (2) is in the range of 1:0.001 to 1:10 in mole ratio, wherein the ratio of said component (1) to said component (3) is in the range of 1:0.001 to 1:10 in terms of mole ratio, and wherein the amount of said compound relative to the titanium compound in said catalyst compnent is in the range of 0.1:1 to 100:1 in terms of Si:Ti ratio.

2. The process of claim 1, wherein the ratio of said organometallic compound to said compound is in the range of 1:0.001 to 1:5 in mole ratio.

3. The process of claim 1, wherein said organometallic compound and said compound are reacted together before use.

4. The process of claim 1, wherein the polymerization reaction is carried out at a temperature in the range of 20.degree. to 300.degree. C. and at a pressure in the range of atmospheric pressure to 70 kg/cm.sup.2.G.

5. The process of claim 1, wherein said .alpha.-olefin is an .alpha.-olefin having 3 to 8 carbon atoms.