JPH0665389A - Production of crosslinked polyolefin - Google Patents

Abstract

PURPOSE:To efficiently obtain a crosslinked polyolefin excellent in resistance to organic solvents by melt compounding a specified olefin copolymer, a polyalkylene oxide and a catalyst. CONSTITUTION:An alkenylsilane/olefin copolymer, a polyalkylene oxide and a catalyst are melt compounded. As the catalyst, a rhodium salt, such as a triphenylphosphine complex of rhodium chloride, or a group IVb metal alkoxide represented by the formula R<1>nM(O-R<2>)4-2 (wherein R<1> and R<2> may be the same or different and are each a 1-12C hydrocarbon group; (n) is an integer of 0 to 3; and M is a metal selected from among titanium, zirconium and hafnium), such as a titanic acid ester, is preferably used. Examples of alkylene oxides serving as the raw material for the polyalkylene oxide include ethylene oxide, propylene oxide, butylene oxide and styrene oxide.

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 and melting a specific copolymer, a specific compound and a catalyst.

[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 a long time to crosslink, and the method of heating, melting and mixing is operability. I have a problem. If the crosslinking can be controlled by the method of heating, melting and mixing, it will be an extremely useful method. Further, polyolefin is inherently lipophilic even when cross-linked, and there is a problem with organic solvent resistance.

[0004]

[Means for Solving the Problems] The present inventors completed the present invention by intensively studying a method for solving the above problems and efficiently producing a crosslinked polyolefin excellent in organic solvent resistance.

That is, the present invention is a method for producing a crosslinked polyolefin, which is characterized in that a copolymer of an alkenylsilane and an olefin, a polyalkylene oxide and a catalyst are heated and melt mixed.

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, the polyalkylene oxide is a polymer of alkylene oxide having at least one OH group at one end, and has a degree of polymerization of 1 or more, particularly 2 or more, Up to about 1000 are available. Examples of the alkylene oxide include ethylene oxide, propylene oxide, butylene oxide, isobutylene oxide, pentylene oxide, styrene oxide and the like.

The ratio of the polyalkylene oxide used to the alkenylsilane / olefin copolymer is usually 100% by weight of the alkenylsilane / olefin copolymer.
It is 0.01 to 20 parts by weight, preferably 0.1 to 10 parts by weight, based on parts by weight. If it is less than this, the improvement effect is small, and if it is more than this, unreacted polyalkylene oxide increases, which is not preferable.

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.

[0023]

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.).

The mixing method of the above-mentioned alkenylsilane / olefin copolymer, polyalkylene oxide, catalyst and, if necessary, mixed polyolefin is not particularly limited, and they are mixed by a usual method and used as they are, or further melt-kneaded. And granulated. Preferably, the catalyst, the copolymer of alkenylsilane and olefin, and the polyalkylene oxide are mixed at the same time as molding, and usually the master pellets of the catalyst are mixed at the time of molding. That is, the catalyst is used as a mixture with a polyolefin containing no alkenylsilane or a mixture with polyarylene oxide. In particular, it is effective to mix pellets in which a polyolefin and a catalyst are mixed with pellets in which a copolymer of alkenylsilane and olefin and polyalkylene oxide are mixed and to heat-melt-mold.
In some cases, the copolymer can be crosslinked by immersing it in a catalyst solution after mixing and molding a copolymer of alkenylsilane and olefin, a polyalkylene oxide, and a polyolefin that is mixed as necessary. The temperature during mixing is not particularly limited, but room temperature is sufficient,
When melted by heating, the melting temperature is usually 150 to 30.
It is carried out at 0 ° C, preferably 180 to 280 ° C, and the temperature for immersing the molded product is room temperature to 150 ° C, preferably 40 to 120 ° C.
℃.

The catalyst is used in an amount of 1 to 0.0000001 mol% when it is dissolved in a solvent, and 1 ppm to 1% when it is mixed at the time of molding.

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.

Crosslinking can be further promoted by further heating the molded product after heat-melt molding, which is more preferable. The heating temperature is 100 to 200 ° C, especially 120 to 18
Crosslinking can be completed by heating at 0 ° C. for several minutes to several tens of hours.

[0028]

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

Example 1 A vibrating 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 diethylaluminum 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.

8 g of polyethylene oxide (molecular weight about 1000) was mixed with 100 g of the obtained copolymer and granulated with an extruder of 20 mm. On the other hand, polypropylene synthesized by the same method without using vinylsilane (intrinsic viscosity 2.04, boiling n-
Heptane-insoluble content 97.8%) and 2 wt% of n-butyl titanate
% So as to be pelletized in the same manner. These two types of pellets were mixed so that the amount of n-butyl titanate was 0.2 wt% and mixed by an injection molding machine (FKS manufactured by Komatsu Ltd.).
55) was heated and melt-mixed at 250 ° C. to produce a molded product. The molded product was not deformed at 200 ° C. at all, and the extraction residue ratio after extraction with boiling xylene for 12 hours was 78%. When the molded product was heat-treated at 180 ° C for 1 hour, the extraction residue ratio after extraction with boiling xylene for 12 hours was 98%.
The weight increase of the moldings after extraction was only 25%. No crack was observed in the molded product after extraction.

Comparative Example 1 A molded product obtained by molding and crosslinking in the same manner as in Example 1 except that divinylbenzene was used instead of polyethylene oxide was evaluated in the same manner. The molded product did not deform even at 200 ° C. The ratio of the extraction residue after time extraction was 99% and the weight increase of the molded product after extraction was 12%, but the molded product after extraction had many cracks.

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%.
A molded product was prepared in the same manner as in Example 1 except that 100 g of this powder was used, and the same procedure as in Example 1 was carried out except that a triphenylphosphine complex of rhodium chloride (used so as to reach 0.01 wt%) was used as a catalyst. When processed in the same way, the molded product after heat treatment did not deform at 200 ° C at all, and it was treated with boiling xylene.
The extraction residue ratio after extraction for 12 hours was 96%, the weight increase of the molded product after extraction was only 18%, and there was no crack.

Example 3 The same procedure as in Example 1 was carried out except that polypropylene oxide (molecular weight about 800) was used instead of polyethylene oxide, and the molded product after heat treatment did not deform at 200 ° C. The ratio of extraction residue after time extraction is 98
%, The increase in the weight of the molded product after extraction was only 22%, and there was no crack.

[0036]

INDUSTRIAL APPLICABILITY By the method of the present invention, a crosslinked polyolefin excellent in organic solvent resistance can be produced, which is industrially extremely valuable.

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Claims (1)

[Claims] 1. A method for producing a crosslinked polyolefin, which comprises melt-mixing a alkenylsilane / olefin copolymer, a polyalkylene oxide and a catalyst with heating.