KR20100045636A - Crome-based mixed catalyst for olefin polymerization - Google Patents

Abstract

PURPOSE: A chrome-based mixed catalyst for an olefin polymerization is provided to apply the catalyst to a yarn molding resin and a mono-filament using high density polyolefin. CONSTITUTION: A chrome-based mixed catalyst for an olefin polymerization contains a mixture including 20~80wt% of silica-titania-cromia tergels catalyst and 80~20wt% of silica-cromia catalyst. The tergels catalyst contains 0.5~2.5wt% of Ti, 0.5~2.0wt% of Cr. The tergels catalyst is activated by plasticizing 4~8 hours at 650~850 deg C.

Description

Chromium-based mixed catalyst for olefin polymerization {CROME-BASED MIXED CATALYST FOR OLEFIN POLYMERIZATION}

The present invention relates to a chromium-based mixed catalyst for olefin polymerization, and more particularly to a chromium-based mixed catalyst in which two different chromium-based catalysts used in the olefin polymerization reaction are mixed.

Chromium-based catalysts for olefin polymerization were first developed in the early 1950's by J. Paul Hogan and Robert L. Banks of Phillips Laboratories. Currently, various types of chromium-based catalysts are used in the polymerization process.

Unlike the Ziegler-Natta catalyst, the chromium-based catalyst requires activation by hot air at 650 ° C. to 850 ° C. before the reactor is introduced. This decrease in sintering (sintering) occurs, there is a problem that the activity of the catalyst (active) falls.

In addition, the chromium-based catalyst has an induction time of 5 minutes to 1 hour before the start of polymerization in the reactor (time required to convert from hexavalent oxide to divalent), and the polymer MI (melt index) is hydrogen concentration. Controlled by the reactor temperature.

By activating the catalyst and reducing it to CO, it is possible to eliminate the induction time and increase the polymerization rate, but carbon monoxide is chemically adsorbed at the catalyst active point to reduce the activity of the catalyst. There is a problem.

The present invention relates to a process for preparing polyolefins of improved physical properties using mixed catalyst compositions.

In order to solve the problems of the prior art as described above, the present invention has excellent mechanical properties and molding processability, chromium-based mixture for olefin polymerization suitable for mono-filament and yarn molding resin of the product of high density polyolefin It is an object to provide a catalyst.

It is another object of the present invention to provide a polyolefin for monofilament and yarn molding resin prepared by the chromium-based mixed catalyst for olefin polymerization.

The above and other objects of the present invention can be achieved by the present invention described below.

In order to achieve the above object, the present invention is made by mixing 20 to 80% by weight of silica-titania-chromia tergels catalyst and 80 to 20% by weight of silica-chromia cogels catalyst, the tergel The catalyst is an olefin polymerization, characterized in that the titanium (Ti) content of 0.5 to 3% by weight, the chromium (Cr) content is 0.5 to 2.0% by weight, and the cogel catalyst has a chromium (Cr) content of 0.5 to 2.0% by weight. A chromium-based mixed catalyst is provided.

The present invention also provides a polyolefin for mono-filament and yarn molding resin produced by the chromium-based mixed catalyst for olefin polymerization.

As described above, according to the present invention, a chromium-based mixed catalyst suitable for application of mono-filament and yarn molding resin and capable of producing a high density polyolefin having excellent mechanical properties and molding processability, and thus There is an effect to provide a polyolefin produced by.

Hereinafter, the present invention will be described in detail.

The chromium-based mixed catalyst for olefin polymerization of the present invention is made by mixing 20 to 80% by weight of silica-titania-chromia tergels catalyst and 80 to 20% by weight of silica-chromia cogels catalyst. The catalyst is titanium (Ti) content of 0.5 to 3% by weight, chromium (Cr) content is 0.5 to 2.0% by weight, the cogel catalyst is characterized in that the chromium (Cr) content is 0.5 to 2.0% by weight.

The cogel catalyst is characterized in that it may further comprise titanium (Ti) in the 1.0 to 2.5% by weight on the surface.

The tergel catalyst was activated by firing at 650 to 850 ° C. for 4 to 8 hours, and the cogel catalyst was activated by firing at 650 to 850 ° C. for 6 to 10 hours and then mixed.

It is preferable that the said olefin is ethylene.

The polyolefin for mono-filament and yarn molding resin of the present invention is characterized by being produced by the chromium-based mixed catalyst for olefin polymerization.

The polyolefin may have a value of Mw (weight average molecular weight) / Mn (number average molecular weight) representing a polydispersity index.

The polydispersity index serves as a criterion indicating the molecular weight distribution of the polymer resin, and when the value thereof is increased, the molecular weight distribution of the polymer resin is increased and the processability is increased.

The polyolefin is preferably applied to mono-filament and yarn molding resin, and particularly preferably to yarn molding resin.

Hereinafter, the present invention will be described in more detail with reference to the following examples. However, the scope of the present invention is not limited to the following examples.

EXAMPLE

Example 1

The silica-titania-chromia tergel catalyst (Magnapore 963, Grace) was activated by firing at a temperature of 695 ° C. for 6 hours using air, and the silica-chromia cogel catalyst (catalyst surface Cr 0.91 wt%) was used for air. It was activated by firing at a temperature of 700 ℃ for 8 hours. 75 wt% of the activated tergel catalyst and 25 wt% of the cogel catalyst were mixed to prepare a chromium-based mixed catalyst.

The chromium-based mixed catalyst and the ethylene monomer were reacted under an isobutane solvent at a reaction temperature of 94 to 99 ° C., a reaction pressure of 600 psi, an ethylene flow rate of 24 to 28 kg / hr, and a reaction time of about 2 hours based on recycle isobutane. Polyethylene resin was prepared.

Example 2

Except that 50 wt% of the tergel catalyst and 50 wt% of the cogel catalyst in Example 1 was carried out in the same manner as in Example 1.

Example 3

Except that 25 wt% of the tergel catalyst and 75 wt% of the cogel catalyst in Example 1 was carried out in the same manner as in Example 1.

Comparative Example 1

Except that the cogel catalyst was not used in Example 1 was carried out in the same manner as in Example 1.

Comparative Example 2

Except that the tergel catalyst was not used in Example 1 was carried out in the same manner as in Example 1.

[Test Example]

The properties of the polyethylene prepared in Examples 1 to 3 and Comparative Examples 1 and 2 were measured by the following method, and the results are shown in Table 1 below.

* Tear Strength-measured according to ASTM D1922.

Tensile Strength-Measured according to ASTM.

 division  Tergel Catalyst  Cogel catalyst  Melt Index  Polydispersity Index (Mw / Mn) Tensile Strength (kg / cm ² ) Tear strength (kg / cm) MD longitudinal direction TD transverse MD longitudinal direction TD transverse Example 1 75 25 0.9 16.5 456 428 201 219 Example 2 50 50 0.9 18.1 485 421 197 228 Example 3 25 75 0.9 17.3 471 403 198 210 Comparative Example 1 100 0 0.9 13.4 441 430 210 194 Comparative Example 2 0 100 0.9 13.8 455 393 203 201

As shown in Table 1, the polyolefins according to the present invention (Examples 1 to 3) were prepared in polyolefins (Comparative Examples 1 and 2) prepared using only a silica-titania-chromia tergel catalyst or a silica-chromia cogel catalyst. In comparison, polydispersity index (processability), tensile strength and tear strength were all excellent.

Claims (4)

20 to 80% by weight of the silica-titania-chromia tergels catalyst and 80 to 20% by weight of the silica-chromia cogel catalyst, The tergel catalyst has a titanium (Ti) content of 0.5 to 2.5% by weight, a chromium (Cr) content of 0.5 to 2.0% by weight, The cogel catalyst is a chromium-based mixed catalyst for olefin polymerization, characterized in that the chromium (Cr) content is 0.5 to 2.0% by weight. The method of claim 1, The tergel catalyst is activated by firing at 650 to 850 ° C. for 4 to 8 hours, and the cogel catalyst is activated by firing at 650 to 850 ° C. for 6 to 10 hours and then mixed. The method of claim 1, The olefin is ethylene-based mixed catalyst for olefin polymerization, characterized in that. A polyolefin for mono-filament and yarn molding resin prepared by the chromium-based mixed catalyst for olefin polymerization of claim 1.