JPH0673193A - Production of cross-linked polyolefin - Google Patents

Abstract

PURPOSE:To readily obtain the subject polymer excellent in handleability and reproducibility by heating a mixture of a copolymer of an alkenylsilane and an olefin and a catalyst in the presence of an alcohol. CONSTITUTION:A mixture of a copolymer of an alkenylsilane and an olefin and a catalyst is heat-treated in the presence of an alcohol (preferably 1-6C alcohol such as methanol) preferably under pressure at 120-180 deg.C for several minutes to tens hours to give the objective polymer. A rhodium salt such as triphenylphosphine complex of rhodium chloride is preferable as the catalyst. The mixture is preferably obtained by blending pellets prepared by mixing a polyolefin with the catalyst with pellets of the copolymer of the alkenylsilane and the olefin, heating, melting and molding.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a method for producing a crosslinked polyolefin. More specifically, it relates to a method for producing a crosslinked polyolefin, which comprises heating a mixture of a specific copolymer and a catalyst under specific conditions.

[0002]

2. Description of the Related Art Crosslinking has been widely carried out for the purpose of improving mechanical properties of polyolefins, solvent resistance, heat resistance and the like. Various methods have already been proposed as cross-linking methods. A method in which a bifunctional monomer and a radical generator are mixed and heated and melted, and a monomer having a hydrolyzable group such as an alkoxysilane is used together. A method of polymerizing and molding, and then hydrolyzing with boiling water or the like to crosslink (JP-A-58-11724).
4), a method of irradiating with radiation to crosslink is well known. There is also a method proposed by the present inventors for treating a copolymer of alkenylsilane with a catalyst (Japanese Patent Application No. 1-241911).

[0003]

The method of treating with a catalyst is an excellent method, but the method of impregnating with a solution of the catalyst has a problem that it takes time to crosslink, and the method of heating, melting and mixing is operability. And there is a problem in reproducibility.

[0004]

[Means for Solving the Problems] The present inventors have completed the present invention by intensively examining a method for producing a crosslinked polyolefin having excellent operability and reproducibility by solving the above problems.

That is, the present invention is a method for producing a crosslinked polyolefin, which comprises heat-treating a mixture of an alkenylsilane / olefin copolymer and a catalyst in the presence of alcohol.

In the present invention, an alkenylsilane having at least one Si--H bond is preferably used, and for example, a compound represented by the following general formula (Formula 1),

[0007]

Embedded image H ₂ C═CH— (CH ₂ ) _n —SiH _P R _3-P (wherein n is 0 to 12, p is 1 to 3 and R is a hydrocarbon residue having 1 to 12 carbon atoms). ) Can be exemplified, and specifically, vinyl silane,
Examples thereof include allylsilane, butenylsilane, pentenylsilane, and compounds in which H of some Si—H bonds of these monomers is replaced with chlorine.

As the olefin, a compound represented by the following general formula (Formula 2),

[0009]

Embedded image H ₂ C═CH—R (wherein R is hydrogen or a hydrocarbon residue having 1 to 12 carbon atoms.)
Can be exemplified, and specifically, ethylene, propylene, butene
In addition to α-olefins such as -1, pentene-1, hexene-1, 2-methylpentene, heptene-1, and octene-1, styrene and its derivatives are also exemplified.

In the present invention, the copolymer of olefin and alkenylsilane can be produced by a bulk polymerization method or a gas phase polymerization method in addition to the solvent method using an inert solvent. As the catalyst used for production, a catalyst composed of a transition metal compound and an organometallic compound is generally used, and a titanium halide is preferably used as the transition metal compound and an organoaluminum compound is preferably used as the organometallic compound.

Specifically, titanium tetrachloride obtained by reducing titanium tetrachloride with metallic aluminum, hydrogen or organic aluminum is modified with an electron-donating compound, an organoaluminum compound, and if necessary, an oxygen-containing organic compound. Such as a catalyst system composed of an electron donating compound, a carrier such as magnesium halide, or a transition metal compound catalyst obtained by supporting titanium halide on the carrier treated with an electron donating compound and an organoaluminum compound, if necessary. A catalyst system consisting of an electron-donating compound such as an oxygen-containing organic compound or a reaction product of magnesium chloride and an alcohol is dissolved in a hydrocarbon solvent and then treated with a precipitating agent such as titanium tetrachloride to form a hydrocarbon solvent. Insolubilize, treat with electron donating compounds such as ester and ether if necessary, then Examples include catalyst systems comprising a transition metal compound catalyst and an organoaluminum compound obtained by a method of treatment with titanium rogenide, and optionally an electron-donating compound such as an oxygen-containing organic compound (see, for example, various references below. An example is given of: Ziegler-Natta Ca
talysts and Polymerization by John Boor Jr (Academi
c Press), Journal of Macromorecular Science Reviews
in Macromolecular Chemistry and Physics, C24 (3) 355
-385 (1984), C25 (1) 578-597 (1985)).

Alternatively, the polymerization can be carried out by using a transition metal catalyst soluble in a hydrocarbon solvent and a catalyst composed of aluminoxane.

As the electron-donating compound, oxygen-containing compounds such as ethers, esters, orthoesters and alkoxysilicon compounds can be preferably exemplified, and alcohols, aldehydes, water and the like can also be used.

As the organoaluminum compound, trialkylaluminum, dialkylaluminum halide, alkylaluminum sesquihalide, and alkylaluminum dihalide can be used. Examples of the alkyl group include methyl group, ethyl group, propyl group, butyl group and hexyl group. Examples of the halide include chlorine, bromine and iodine. Further, an aluminoxane which is an oligomer or a polymer obtained by reacting the above organoaluminum with water or crystal water can also be used.

The alkenylsilane and the olefin are polymerized in a proportion of 0.1 to 30 mol%, preferably 0.
It is 5 to 10 mol%. When it is used as a mixture with another olefin polymer, it is 1 to 20 mol%.

The molecular weight of the polymer is not particularly limited, but from the viewpoint of improving the physical properties of the molded product, the higher the molecular weight, the higher the degree of crosslinking can be achieved with a small alkenylsilane content. Also, in terms of moldability, if the molecular weight is too high, the moldability will deteriorate. Therefore, the intrinsic viscosity measured with a tetralin solution at 135 ° C is preferably 0.5 to
It is about 10, particularly preferably about 1.0 to 5.0.

A graft copolymer obtained by graft-polymerizing an alkenylsilane on a polyolefin (for example, the following mixed polyolefin can be used) can be used for the purpose of the present invention. There is no particular limitation as to the method for grafting alkenylsilane on the polymer, and the method and conditions used for ordinary graft copolymerization can be used. Normally, the polyolefin and alkenylsilane used are radical initiator Graft copolymerization can be easily carried out by heating above the decomposition temperature of.

In the present invention, the following polyolefins may be mixed and used, if desired. The polyolefin used as a mixture with the above copolymer, if necessary, is an olefin represented by the above general formula (formula 2), specifically ethylene, propylene, butene-1, pentene-1, hexene.
-1,2-methylpentene, heptene-1, octene-1, and other α-olefins, homopolymers of styrene or its derivatives, random copolymers of each other, or olefins alone, or small amounts of other Examples thereof include so-called block copolymers produced by copolymerizing with an olefin and then copolymerizing two or more kinds of olefins.

Methods for producing these polyolefins are already known and various brands are available on the market. It can also be produced by the same method as the method for producing a copolymer of olefin and alkenylsilane except that alkenylsilane is not used.

In the present invention, as a catalyst, a rhodium salt such as a triphenylphosphine complex of rhodium chloride, or an alkoxy compound of a metal of Group IVB of the periodic table represented by the following general formula (Formula 3) such as a titanate ester is used. It is preferably exemplified.

[0021]

Embedded image R ¹ _n M (OR ² ) _4-n (wherein R ¹ and R ² are the same or different hydrocarbon residues having 1 to 12 carbon atoms, n is an integer of 0 to 3 and M is titanium). , A metal selected from zirconium and hafnium.).

There are no particular restrictions on the method of mixing the above-mentioned alkenylsilane / olefin copolymer, catalyst, and, if necessary, the mixed polyolefin, and they are mixed in a powder state by a conventional method and used as they are, or further melt-kneaded. Granulated. Preferably, the catalyst and the copolymer of the alkenylsilane and the olefin are mixed at the same time as the molding, and the master pellets of the catalyst are usually mixed at the molding. That is, the catalyst is used as a mixture with a polyolefin containing no alkenylsilane. In particular, it is effective to mix pellets in which polyolefin and a catalyst are mixed, pellets in which a copolymer of alkenylsilane and olefin and, if necessary, polyolefin are mixed, and to heat-melt-mold.

As the molding method, injection molding, extrusion molding,
Examples include press molding. Here, the alkenylsilane concentration in the mixture is 0.01 to 20 mol%, preferably
When mixed so as to be 0.1 to 10 mol%, a crosslinked polyolefin having a high concentration of crosslinking points can be obtained.

In the present invention, the heating in the presence of alcohol is performed on a mixture of an alkenylsilane / olefin copolymer and a catalyst, and is usually performed on a molded product molded into a desired shape. Be seen. Although it is possible to proceed with crosslinking only by heating the molded article containing the catalyst, in the present invention, by heating in the presence of alcohol, as compared with the case of heating in the absence of alcohol, much more. It is possible to obtain a crosslinked molded product quickly and with good reproducibility.

Examples of the alcohol include aliphatic, alicyclic, and aromatic alcohols having 1 to 20 carbon atoms. Particularly, when an alcohol having 1 to 6 carbon atoms and having a relatively low boiling point is used, the alcohol after heat treatment is used. Is easy to remove.

The heating temperature is 100 to 200 ° C., especially 120
The heating is performed at ˜180 ° C. for several minutes to tens of hours. In this case, when alcohol having a low boiling point is used, heating under pressure is more effective.

[0027]

EXAMPLES The present invention will be further described with reference to the following examples.

Example 1 A vibration mill equipped with four grinding pots having an inner volume of 4 liters and containing 9 kg of steel balls having a diameter of 12 mm was prepared. In each pot under a nitrogen atmosphere, 300 g of magnesium chloride, 60 ml of tetraethoxysilane and 45 of α, α, α-trichlorotoluene
ml was added and crushed for 40 hours. Co-ground product 300 thus obtained
In a 5 liter flask, add 1.5 liters of titanium tetrachloride and 1.5 liters of toluene, and add 30 liters at 100 ° C.
After stirring for a minute, the supernatant was removed. Add again 1.5 liters of titanium tetrachloride and 1.5 liters of toluene,
The mixture was stirred at 100 ° C for 30 minutes, and the supernatant was removed. Then, the solid content was repeatedly washed with n-hexane to obtain a transition metal catalyst slurry. When a part of the sample was sampled and the titanium content was analyzed, the titanium content was 1.9 wt%.

40 ml of toluene, 100 mg of the above transition metal catalyst, 0.128 ml of diethylaluminium chloride, 0.06 ml of methyl p-toluate and 0.20 ml of triethylaluminum were placed in an autoclave having an internal volume of 5 liters under a nitrogen atmosphere, and 1.5 kg of propylene and 80 g of vinylsilane were added. In addition, hydrogen
After 0.5 N liter was injected under pressure, polymerization was carried out at 75 ° C. for 2 hours. After the polymerization, unreacted propylene was purged, the powder was taken out, filtered and dried to obtain 480 g of powder.

The powder obtained had an intrinsic viscosity (hereinafter abbreviated as η) of 2.35 measured with a tetralin solution at 135 ° C.
The melting point and crystallization temperature were measured as the maximum peak temperature by raising or lowering the temperature at 10 ° C / min using a differential thermal analyzer. Melting point 156 ° C, crystallization temperature 120 ° C
Was a crystalline propylene copolymer. According to elemental analysis, it contained 1.3 wt% of vinylsilane unit.

100 g of the obtained copolymer and 100 g of polypropylene (intrinsic viscosity 2.04, boiling n-heptane insoluble matter 97.8%) synthesized by the same method without using vinylsilane were granulated by an extruder to form pellets, and 2 wt% n-butyl titanate to polypropylene containing no vinyl silane
% To obtain pellets. An injection molding machine (FKS55) manufactured by Komatsu Ltd. was used by mixing these two types of pellets so that n-butyl titanate was 0.2 wt%.
Was melted and mixed by heating to produce a molded product. This molded product was extracted with boiling xylene for 12 hours, and the ratio of the extraction residue was 36.
%Met. The molded product was placed in an autoclave with an internal volume of 3 liters together with 10 ml of methanol at 180 ° C for 10
After heat treatment for 1 minute, the ratio of the extraction residue extracted with boiling xylene for 12 hours was 95%, and the weight increase of the molded product after extraction was 42%.

Comparative Example 1 Example 1 except that heating was done without the presence of methanol.
When molded and cross-linked in the same manner as above, the proportion of the extraction residue extracted with boiling xylene for 12 hours was 52%.

Example 2 A propylene copolymer having an allylsilane content of 0.25 wt% was prepared by polymerizing in the same manner as in Example 1 except that 1 g of allylsilane was used instead of vinylsilane. The η of the copolymer was 1.85, the melting point was 158 ° C., the crystallization temperature was 115 ° C., and the extraction residue ratio after extraction with boiling n-heptane for 6 hours was 96.8%.
200g of this powder was pelletized without using polypropylene as one component and used as alcohol.
A molded product was prepared in the same manner as in Example 1 except that n-butanol was used, and the degree of crosslinking was measured. The molded product after heat treatment was not deformed at 200 ° C. and was extracted with boiling xylene for 12 hours. The ratio of the extraction residue was 97%, and the weight increase of the molded product after extraction was 72%.

COMPARATIVE EXAMPLE 1 The procedure of Example 2 was repeated except that n-butanol was heated in the same manner as in Example 2, except that the mixture was cross-linked and was extracted with boiling xylene for 12 hours. The proportion of the extraction residue was 68%.

[0035]

INDUSTRIAL APPLICABILITY By the method of the present invention, a crosslinked polyolefin can be easily produced and is industrially very valuable.

Claims (1)

[Claims] 1. A process for producing a crosslinked polyolefin, which comprises heat-treating a mixture of an alkenylsilane / olefin copolymer and a catalyst in the presence of alcohol.