Process for producing catalyst for ethylene polymerization...

Details Process for producing catalyst for ethylene polymerization... Process for producing catalyst for ethylene polymerization...

2001-03-16

2003-03-25

Wu, David W. (Department: 1713)

Synthetic resins or natural rubbers -- part of the class 520 ser

Synthetic resins

Polymers from only ethylenic monomers or processes of...

C526S352000, C526S124300, C526S125100, C526S119000, C502S103000, C502S118000, C502S125000, C502S127000, C502S126000

Reexamination Certificate

active

06538079

ABSTRACT:

FIELD OF THE INVENTION
The present invention relates to a process for producing a catalyst for ethylene polymerization, and a process for producing an ethylene polymer.
BACKGROUND OF THE INVENTION
An ethylene polymer having a low content of a lower molecular weight component is desired from a viewpoint of properties of films obtained therefrom such as, for example, transparency, impact resistance and blocking resistance.
As a polymerization catalyst having a superior catalyst efficiency, there is known a catalyst comprising (i) a solid catalyst component obtained from a combination of a specific magnesium compound and (ii) a specific titanium compound (cf., for example, JP-B46-34092, JP-B47-41676, JP-B55-23561 and JP-B 57-24361). However, an ethylene polymer obtained using such a catalyst is not satisfactory from a viewpoint of blocking resistance.
Further, as a polymerization catalyst for producing a highly crystalline propylene polymer, there is known a catalyst comprising a solid catalyst component obtained using an oxygen-containing electron donor such as an ester as an internal donor (cf., for example, JP-B 52-39431, JP-B 52-36786, JP-B 1-28049 and JP-B 3-43283). However, a copolymer of ethylene and an &agr;-olefin obtained using such a catalyst is also unsatisfactory from a viewpoint of blocking resistance.
Furthermore, JP-A 11-80234 and JP-A 11-322833 disclose a catalyst for ethylene polymerization, which can produce an ethylene polymer having a low content of a lower molecular weight component. However, from a viewpoint of increasing quality of the ethylene polymer, an ethylene polymer having a further low content of a lower molecular weight component is desired.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a process for producing a catalyst for ethylene polymerization, which can produce an ethylene polymer having a low content of a lower molecular weight component.
It is another object of the present invention to provide a process for producing an ethylene polymer having a low content of a lower molecular weight component.
The present invention provides a process for producing a catalyst for ethylene polymerization, which comprises the step of contacting with one another:
(i) a solid catalyst component containing at least titanium, magnesium and halogen atoms;
(ii) an organoaluminum compound; and
(iii) a heterocyclic compound.
The present invention also provides a process for producing an ethylene polymer, which comprises the steps of:
(1) contacting with one another (i) a solid catalyst component containing at least titanium, magnesium and halogen atoms, (ii) an organoaluminum compound and (iii) a heterocyclic compound to obtain a catalyst for ethylene polymerization, and
(2) polymerizing ethylene, or ethylene and at least one kind of an addition polymerizable comonomer other than ethylene, in the presence of the obtained catalyst for ethylene polymerization to obtain an ethylene polymer.
DETAILED DESCRIPTION OF THE INVENTION
Heterocyclic Compound
A heterocyclic compound used in the present invention is not limited in kind. The heterocyclic compound may be either an aromatic heterocyclic compound or an aliphatic heterocyclic compound. A preferred heterocylic compound is a 3- to 8-membered heterocyclic compound.
As the heterocyclic compound, for example, those represented by the following formulas are enumerated. In the formulas, X is a hydrogen atom, a hydrocarbon group, an hydrocarbyloxy group or an amino group substituted with two hydrocarbon groups, and respective X's in the molecule may be bonded with one another. The heterocyclic compound may be that formed by bonding two or more compounds selected from the compounds mentioned below with one another at their X portions.
A hetero atom constituting the ring of the heterocyclic compound is preferably selected from the group consisting of Group 15 elements and Group 16 elements. Of these, more preferable is that selected from the group consisting of nitrogen, phosphorus, oxygen and sulfur atoms. Much more preferable is that selected from the group consisting of nitrogen, phosphorus, oxygen and sulfur atoms, provided that at least one of the hetero atoms constituting the ring is an oxygen atom.
Preferred heterocyclic compounds are those having (i) a hetero atom selected from the group consisting of nitrogen,
phosphorus, oxygen and sulfur atoms as the hetero atom constituting the ring, and (ii) at least one —C—O—C— bond in the ring. More preferred heterocyclic compounds are those having an oxygen atom as any of the hetero atom constituting the ring system.
Specific examples of preferred heterocyclic compounds are ethylene oxide, propylene oxide, trimethylene oxide, tetrahydrofuran, 2,5-dimethoxytetrahydrofuran, tetrahydropyran, hexamethylene oxide, 1,3-dioxepane, 1,3-dioxane, 1,4-dioxane, 1,3-dioxolan, 2-methyl-1,3-dioxolan, 2,2-dimethyl-1,3-dioxolan, 4-methyl-1,3-dioxolan, furan, 2,5-dimethylfuran and s-trioxan. Particularly preferred heterocyclic compounds are 4- to 8-membered compounds having a —C—O—C—O—C— bond.
The heterocyclic compound is used in an amount of usually from 1 mol to 2000 mol, and particularly preferably from 5 mol to 1000 mol, per mol of the titanium atom in the solid catalyst component. An amount of the heterocyclic compound used against the organoaluminum compound is usually from 0.001 mol to 10 mol, and particularly preferably from 0.01 mol to 5 mol, per mol of the aluminum atom in the organoaluminum compound.
Solid Catalyst Component
A solid catalyst component used in the present invention may be any known solid catalyst component containing titanium, magnesium and halogen atoms.
Examples thereof are those disclosed in JP-B 46-34092, JP-B 47-41676, JP-B 55-23561, JP-B 57-24361, JP-B 52-39431, JP-B 52-36786,JP-B1-28049,JP-B3-43283,JP-A4-80044,JP-A55-52309, JP-A 58-21405, JP-A 61-181807, JP-A 63-142008, JP-A 5-339319, JP-A 54-148093, JP-A 4-227604, JP-A 6-2933, JP-A 64-6006, JP-A 6-179720, JP-B 7-116252, JP-A 8-134124, JP-A 9-31119, JP-A 11-228628, JP-A 11-80234 and JP-A 11-322833.
As the solid catalyst component, preferred are those containing an electron donor in addition to the titanium, magnesium and halogen atoms.
As a process for producing the solid catalyst component, the following processes (1) to (5) can be exemplified:
(1) process comprising the step of contacting a magnesium halide compound and a titanium compound with each other,
(2) process comprising the step of contacting a magnesium halide compound, an electron donor and a titanium compound with one another,
(3) process comprising the step of dissolving a magnesium halide compound and a titanium compound in an electron donative solvent to obtain a solution, and impregnating a carrier with the solution,
(4) process comprising the step of contacting a dialkoxymagnesium compound and a titanium halide compound with each other, and
(5) process comprising the step of contacting (a) a solid catalyst component precursor containing a magnesium atom, a titanium atom and a hydrocarbyloxy group, (b) a halogeno compound having a capability of halogenation and (c) an electron donor with one another.
Of these, the process (5) is preferable.
Preferred solid catalyst component precursors are solid products (1) and (2) mentioned below:
(1) solid product obtained by reducing a titanium compound represented by the following formula with an organomagnesium compound in the presence of an organosilicon compound having an Si—O bond,
Ti(OR
1
)
a
X
4−a
wherein R
1
is a hydrocarbon group having 1 to 20 carbon atoms, X is a halogen atom, and “a” is a number satisfying 0<a≦4 (cf. JP-A 11-80234), and
(2) solid product obtained by reducing the titanium compound represented by the above formula with an organomagnesium compound in the presence of an organosilicon compound having an Si—O bond and a porous carrier (cf. JP-B 4-57685).
Examples of R
1
in the above formula are alkyl groups such as methyl, ethyl, propyl, i-propyl, butyl, i-butyl, amyl, i-amyl, hexyl, heptyl, octyl, decyl and dodecyl groups; aryl grou

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