JP3193765B2 - Method for producing crosslinked polyolefin molded article - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a crosslinked polyolefin molded article. More specifically, the present invention relates to a method for producing a crosslinked polyolefin molded article by irradiating a molded article comprising a specific copolymer and a specific silicone with radiation.

[0002]

2. Description of the Related Art Crosslinking of a polyolefin for the purpose of improving mechanical properties, improving solvent resistance, improving heat resistance and the like is widely performed. Various cross-linking methods have already been proposed, including a method of mixing and heating and melting a bifunctional monomer and a radical generator, and a method of mixing a monomer having a hydrolyzable group such as alkoxysilane. A method of polymerizing, molding, and then hydrolyzing with boiling water or the like to crosslink (JP-A-58-11724)
4), methods of cross-linking by irradiation with radiation are well known. There is also a method of treating a alkenylsilane copolymer with a catalyst proposed by the present inventors (Japanese Patent Application No. 1-241911).

[0003]

Although the heat resistance is considerably improved even when the crosslink density is low, the crosslink density is further improved in order to use a crosslinked molded article as a structure or to improve the solvent resistance at high temperatures. It is desired to do.

[0004]

Means for Solving the Problems The present inventors have intensively studied a method for solving the above problems and easily producing a crosslinked polyolefin molded article having a high crosslinking density and completed the present invention.

That is, the present invention provides a compound represented by the following general formula (Formula 4)

Embedded image (Where n is 0 to 12, p is 1 to 3, and R is 1 to 12 carbon atoms.
Hydrocarbon residues. A method for producing a crosslinked polyolefin molded article, comprising irradiating a molded article comprising a copolymer of an alkenylsilane and an olefin represented by the formula (1) and a silicone containing a Si—H group with radiation.

[0006] alkenylsilane used in the present invention is a compound represented by the above following general formula (Formula 4).

Specifically, vinyl silane, allyl silane,
Butenyl silane and pentenyl silane can be exemplified.

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

[0009]

Embedded image H ₂ CHCH—R (where R is hydrogen or a hydrocarbon residue having 1 to 12 carbon atoms)
Can be exemplified, specifically, ethylene, propylene, butene
In addition to α-olefins such as -1, pentene-1, hexene-1, 2-methylpentene, heptene-1, and octene-1, styrene or a derivative thereof is 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 a solvent method using an inert solvent. Further, a catalyst comprising a transition metal compound and an organometallic compound is generally used as a catalyst used in the production. 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 organic aluminum compound, and if necessary, an oxygen-containing organic compound. A catalyst system comprising an electron donating compound such as, or a carrier such as magnesium halide or a transition metal compound catalyst obtained by supporting them with an electron donating compound and supporting a titanium halide, and an organoaluminum compound. 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 precipitant such as titanium tetrachloride to form a hydrocarbon solvent. Insolubilize and treat with an electron-donating compound such as an ester or ether if necessary. Examples of the catalyst system include a transition metal compound catalyst obtained by a method of treating with a titanium logenide and an organoaluminum compound, and an electron-donating compound such as an oxygen-containing organic compound as required (for example, various types of compounds described in the following literature). Examples are described: Ziegler-Natta Ca
talysts and Polymerization by John Boor Jr (Academi
c Press), Journal of Macromorecular Science Reviews
in MacromolecularChemistry and Physics, C24 (3) 355
-385 (1984) and C25 (1) 578-597 (1985)).

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

As the electron-donating compound, oxygen-containing compounds such as ethers, esters, orthoesters and alkoxysilicon compounds can be preferably exemplified, and alcohols, aldehydes and water 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 a methyl group, an ethyl group, a propyl group, a butyl group, and a hexyl group. Illustrative examples of the halide include chlorine, bromine and iodine. Aluminoxane, which is an oligomer to a polymer obtained by reacting the above-mentioned organoaluminum with water or water of crystallization, can also be used.

Here, the polymerization ratio of alkenylsilane and olefin is usually 0.1 to 30 mol%, preferably 0.1 to 30 mol%, from the viewpoint of increasing the degree of crosslinking.
5 to 10 mol%. When it is used in a mixture with another olefin polymer, the content 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 even with a small alkenylsilane content. In terms of moldability, if the molecular weight is too high, moldability deteriorates. Therefore, the intrinsic viscosity measured with a tetralin solution at 135 ° C. is preferably 0.5 to
It is about 10 and particularly preferably about 1.0 to 5.0.

A graft copolymer obtained by graft-polymerizing an alkenylsilane onto a polyolefin (for example, a polyolefin used as a mixture as described below) can also be used for the purpose of the present invention. There is no particular limitation on the method of grafting the alkenyl silane to the method, and the method and conditions used for ordinary graft copolymerization can be used, and the usually used polyolefin and alkenyl silane are radical initiators in the presence of a radical initiator such as peroxide. The graft copolymerization can be easily performed by heating to a temperature equal to or higher than the decomposition temperature.

In the present invention, the following polyolefins can be mixed and used as required. If necessary, the polyolefin used by mixing with the above copolymer may be an olefin represented by the above general formula (Formula 2), specifically, ethylene, propylene, butene-1, pentene-1, hexene
Α-olefins such as -1,2-methylpentene, heptene-1, and octene-1, or homopolymers of styrene or its derivatives, random copolymers of each other, or olefins at first, or small amounts of other olefins A so-called block copolymer produced by copolymerizing with an olefin and then copolymerizing two or more olefins is exemplified.

The methods for producing these polyolefins are already known, and various brands are available on the market. Alternatively, the alkenyl silane can be produced by using the same method as that for producing the copolymer of olefin and alkenyl silane except that alkenyl silane is not used.

In the present invention, any silicone having a Si—H group in the polymer chain can be used as the polysilicone containing a Si—H group. Can be synthesized by reacting water with a compound represented by It can be a concentration.

[0021]

RHSiCl ₂ (wherein R is a hydrocarbon residue having 1 to 12 carbon atoms).

The molecular weight of the polysilicone is not particularly limited, but generally a number average molecular weight of about 1,000 to 100,000 is used.

The ratio of the polysilicone to the alkenylsilane / olefin copolymer is usually 0.1 to 60 parts by weight, preferably 1.0 to 40 parts by weight, per 100 parts by weight of the alkenylsilane / olefin copolymer. . If the amount is smaller than this, the improvement effect is small, and if it is larger, the rigidity becomes poor, which is not preferable.

The method of mixing the above-mentioned alkenylsilane-olefin copolymer, polysilicone and, if necessary, polyolefin is not particularly limited, and may be used in the form of a powder in a usual manner and used directly, or may be further melt-kneaded. Granulated. The molding is performed by injection molding, extrusion molding, press molding or the like. Here, when the mixture is mixed so that the alkenylsilane concentration in the mixture is 0.01 to 20 mol%, preferably 0.1 to 10 mol%, a crosslinked polyolefin molded article having a high crosslink point concentration can be obtained.

In the present invention, radiation means electron beam, γ
Examples include a line, an X-ray, and an ultraviolet ray. Irradiation is performed after forming a desired molded product from the mixture of the alkenylsilane copolymer and polysilicone. As a radiation source, γ-rays and X-rays are preferable from the viewpoint of transparency, and the irradiation dose is usually about 0.1 to 100 Mrad, preferably 1 to 50 Mrad.
It is about. The irradiation is performed at a temperature of 50 ° C. or lower, and it is not necessary to perform the irradiation at a low temperature. If the irradiation is performed at a high temperature, there are problems such as deformation of the molded product and inefficient crosslinking. Therefore, it is preferable that the irradiation be performed at a relatively low temperature and that the radical be completely eliminated by heating after the irradiation.

[0026]

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

Example 1 A vibrating mill equipped with four 4-liter crushing pots containing 9 kg of steel balls having a diameter of 12 mm and having a capacity of 4 liters is prepared. Under a nitrogen atmosphere, 300 g of magnesium chloride, 60 ml of tetraethoxysilane and 45 ml of α, α, α-trichlorotoluene were added to each pot.
ml was added and crushed for 40 hours. Co-ground product 300 thus obtained
g in a 5 liter flask, 1.5 liters of titanium tetrachloride and 1.5 liters of toluene are added.
The mixture was stirred for minutes, and then the supernatant was removed. Add 1.5 liters of titanium tetrachloride and 1.5 liters of toluene again,
The mixture was stirred at 100 ° C. for 30 minutes, and then the supernatant was removed. Thereafter, the solid content was repeatedly washed with n-hexane to obtain a transition metal catalyst slurry. When a part was sampled and analyzed for titanium content, the titanium content was 1.9 wt%.

In a 5 liter autoclave, under a nitrogen atmosphere, 40 ml of toluene, 100 mg of the above-mentioned transition metal catalyst, 0.128 ml of diethylaluminum chloride, 0.06 ml of methyl p-toluate and 0.20 ml of triethylaluminum were placed, and 1.5 kg of propylene and 80 g of vinylsilane were added. Plus hydrogen
After injection of 0.5N liter, polymerization was carried out at 75 ° C for 2 hours. After the polymerization, unreacted propylene was purged, the powder was taken out, and dried by filtration to obtain 480 g of powder.

The resulting powder has 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, and the melting point was 156 ° C. and the crystallization temperature was 120 ° C.
Is a crystalline propylene copolymer. According to elemental analysis, it contained 1.3 wt% of a vinylsilane unit.

To 300 g of the obtained copolymer, 50 g of polyphenylsilicone (degree of polymerization: about 1800) synthesized by reacting phenyldichlorosilane and water was added, and the mixture was granulated with an extruder having a diameter of 20 mm and then press-molded to obtain a thickness. A molded product of 1 mm was obtained. The molded article was irradiated with 5 Mrad of γ-ray at 3.2 Mrad / h at 30 ° C.
This molded product did not deform at all even at 200 ° C., the ratio of the extraction residue extracted with boiling xylene for 12 hours was 96%, and the weight increase of the molded product after extraction was only 15%.

The following physical properties of the molded product were measured. Flexural ^{modulus: kg / cm 2 ASTM D747 (} 23 ℃) Tensile yield ^{strength: kg / cm 2 ASTM D638 (} 23 ℃) Izod (notched) impact ^{strength: kg · cm / cm 2 ASTM} D256 (20 ℃, - 10 ° C.) the flexural modulus is 17800kg / cm ^2, the tensile yield strength 310 kg / c
m ^2, respectively Izod impact strength 65,44kg · cm / cm ²
Met.

Comparative Example 1 A molded and crosslinked product was molded and crosslinked in the same manner as in Example 1 without using polyphenylsilicone. The molded product was not deformed even at 200 ° C.
The ratio of the extraction residue extracted for time was 94%, and the weight increase of the molded product after extraction was 88%. The physical properties flexural modulus of the molded product is 20500kg / cm ^2, the tensile yield strength is 410 kg / cm ^2, an Izod impact strength was respectively 8,2kg · cm / cm ^2.

Example 2 A propylene copolymer having an allylsilane content of 0.25 wt% was produced by polymerization 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 ratio of extraction residues when extracted with boiling n-heptane for 6 hours was 96.8%.
A molded article was prepared in the same manner as in Example 1 except that 500 g of this powder was used, and treated in the same manner as in Example 1. The physical properties of the molded article were as follows. Flexural rigidity is 16700kg /
cm ² , tensile yield strength was 320 kg / cm ² , and Izod impact strength was 63 and 41 kg · cm / cm ² , respectively. Molded products are
Even at 200 ° C., there was no deformation, and 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 only 41%.

[0034]

The molded article of the present invention is a crosslinked polyolefin molded article having excellent solvent resistance and excellent impact resistance, and is extremely valuable industrially.

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Claims (1)

(57) [Claims] 1. A following general formula (Formula 1) ## STR1 ## (Where n is 0 to 12, p is 1 to 3, and R is 1 to 12 carbon atoms.
Hydrocarbon residues. A method for producing a crosslinked polyolefin molded article, comprising irradiating a molded article comprising a copolymer of an alkenylsilane and an olefin represented by the formula (1) and a silicone containing a Si—H group with radiation.