JP3177335B2 - Crosslinked polyolefin molded article and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a crosslinked polyolefin molded article and a method for producing the same. More specifically, the present invention relates to a crosslinked polyolefin molded article obtained by contacting a specific copolymer, a polyalkadiene and a catalyst. The present invention also relates to a method for producing a crosslinked polyolefin molded article by subjecting a molded article comprising a specific copolymer, a polyalkadiene and a catalyst to heat treatment or irradiation with radiation.

[0002]

2. Description of the Related Art Crosslinking is widely performed for the purpose of improving the mechanical properties, solvent resistance, and heat resistance of polyolefins. 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 processing a copolymer of proposed alkenylsilane by the present inventors with a catalyst (Japanese open <br/> flat 3-106951).

[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 solved the above-mentioned problems and have intensively studied a crosslinked polyolefin molded article having excellent physical properties to complete the present invention.

That is, the present invention relates to a syndiotactic structure.
Copolymers and polyalkadienes and rhodium salts and Formula alkenyl silane and an olefin not (of 8)

Embedded image (Wherein R ¹ and R ² are the same or different and have 1 to 12 carbon atoms)
A hydride residue, n is an integer of 0 to 3, M is titanium, zirconium
Metal selected from uranium and hafnium. ) Period
It is a crosslinked polyolefin molded product obtained by subjecting a catalyst selected from alkoxy compounds of Group IVB metals to contact treatment. Further, a mixture comprising a copolymer of alkenylsilane and olefin, a polyalkadiene, and a catalyst represented by the above general formula (Formula 8) is melt-molded, and then heat-treated at a temperature not higher than the deformation temperature of the molded product. A method for producing a crosslinked polyolefin molded article, characterized by irradiating the molded article with radiation.

In the present invention, alkenyl silanes having at least one Si—H bond are preferably used, for example, a compound represented by the following general formula (Chemical Formula 1):

[0007]

Embedded image H ₂ C = CH— (CH ₂ ) _n —SiH _P R _3-P (where 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, specifically, vinyl silane,
Examples thereof include allylsilane, butenylsilane, pentenylsilane, and compounds in which H of Si—H bond in some of these monomers is substituted with chloro.

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 0.5.
It is about 10 dl / g , particularly preferably about 1.0 to 5.0 dl / g .

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, examples of the polyalkadiene include polybutadiene, polyisoprene, polychloroprene and the like.
H-groups, carboxylic acid groups and the like, or copolymers of butadiene, isoprene, chloroprene and the like with other olefins, for example, styrene-butadiene rubber, acrylonitrile-butadiene rubber, or ethylene-propylene-alkadiene copolymer Although coalescence is also exemplified, in particular, polybutadiene, polyisoprene, polychloroprene, polybutadiene having an OH group, a carboxylic acid group added to the terminal thereof, styrene-butadiene rubber, acrylonitrile-butadiene rubber and the like have a large content of alkadiene. Are preferably used.

The ratio of the polyalkadiene 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. is there. 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, polyalkadiene and, if necessary, the polyolefin to be mixed is not particularly limited, and may be used in the form of a powder mixed in a usual manner.
Furthermore, it is melt-kneaded and granulated. The shaping is performed prior to the contact with the catalyst described below, or the catalyst is brought into contact with the catalyst at the same time as the shaping. Examples of the molding method include injection molding, extrusion molding, and press molding. Here, the concentration of the alkenylsilane in the mixture is 0.01 to 20 mol%, preferably 0.1 to 20 mol%.
When mixed so as to be 10 mol%, a crosslinked polyolefin having a high concentration of crosslink points can be obtained.

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

[0024]

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 , Zirconium, hafnium.)

In the present invention, the molded product is then subjected to a contact treatment with a catalyst. Although there is no particular limitation on the contact treatment method, it is general that the above molded product is contacted with a solution of a catalyst. After contacting with the catalyst solution, the catalyst can be removed from the solution and heated to accelerate the crosslinking reaction. The contact treatment temperature is generally from room temperature to the melting point of the polymer, and it is preferable to contact the catalyst solution at room temperature to 100 ° C. Under conditions where no solvent is present, it is general to heat to 50 to 160 ° C. In addition, as a method of contacting with the catalyst at the same time as molding, the catalyst may be coexisted during mixing, or a mixture containing the alkenylsilane copolymer and a mixture containing the catalyst without containing the alkenylsilane copolymer. Is prepared in advance, and then the two are mixed, heated, melted and molded.

Specific examples of the solvent used here include hydrocarbon compounds having 1 to 20 carbon atoms and halogenated hydrocarbon compounds.
Aromatic hydrocarbon compounds are preferably used. Specifically, benzene, toluene, xylene, ethylbenzene,
Examples include dichloromethane, chloroform, dichloroethane, trichloroethane, perchloroethane, etc.
It is used after being dissolved so as to have a catalyst concentration of 0.1 to 10,000 ppm.

When the catalyst is heated and melted and brought into contact with the catalyst, the proportion of the catalyst used in the entire mixture is 1 to 1.
It is preferably 10,000 ppm, especially 10 to 5000 ppm. 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.

The method of heating and melting the alkenylsilane-olefin copolymer, polyalkadiene and catalyst, and if necessary, the polyolefin to be mixed, is not particularly limited, and is mixed in a usual manner in a powder state and molded as it is. Or, a pellet containing a catalyst and a pellet containing a copolymer of an alkenylsilane (If the copolymer of an alkenylsilane and a catalyst are contained in the same pellet, crosslinking proceeds during granulation, resulting in poor moldability. ), And then both can be mixed and molded. Although the reason is unknown, the presence of the polyalkadiene suppresses the progress of cross-linking when the catalyst and the alkenylsilane copolymer are melted by heating, and facilitates hot-melt molding. Examples of the molding method include injection molding, extrusion molding, and press molding, and it is particularly effective when applied to extrusion molding and injection molding. The molding temperature is not particularly limited as long as it is a temperature at which the polymer flows and is equal to or lower than the decomposition temperature. Specifically, 150-300 ° C
It is common to do with.

In the present invention, the heat-melt molded product can be further cross-linked by further heat treatment. The heating temperature is preferably higher as long as the molded article is not deformed, since a molded article having a high crosslinking density can be obtained by a short heat treatment. The heating temperature is usually 80 to 17
0 ° C., and the heating time is several minutes to several hundred hours. When a copolymer of propylene and alkenylsilane is used, heating at 155 ° C. for 1 hour is sufficient.

In the present invention, it is also possible to further promote crosslinking by irradiating the heat-melt molded product with radiation. Here, examples of the radiation include an electron beam, γ-ray, X-ray, and ultraviolet ray. Irradiation is performed after forming a desired molded product from a mixture of the above-mentioned alkenylsilane copolymer, polyalkadiene and catalyst. As a radiation source, γ-rays and X-rays are preferable from the viewpoint of transparency.
Usually, it is about 0.1 to 100 Mrad, preferably about 1 to 50 Mrad. The irradiation temperature is not particularly limited, and it is possible to perform the irradiation at a relatively high temperature because the crosslinking is partially progressed by the above-mentioned hot melt molding. If the irradiation is performed at a high temperature, the quenching of the radical after irradiation becomes unnecessary. Usually, it is carried out at normal temperature to 170 ° C.

[0031]

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

Example 1 A vibrating mill equipped with four crushing pots having a capacity of 4 liters and containing 9 kg of steel balls having a diameter of 12 mm was 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 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.
dl / g , and 10 ° C./min using a differential thermal analyzer.
When the melting point and the crystallization temperature were measured as the maximum peak temperatures by raising or lowering the temperature in the above, it was a crystalline propylene copolymer having a melting point of 156 ° C. and a crystallization temperature of 120 ° C.
According to elemental analysis, it contained 1.3 wt% of a vinylsilane unit.

Polybutadiene (300 g) was added to 300 g of the obtained copolymer.
100 g of Nipol BR1220 (manufactured by Nippon Zeon Co., Ltd.) was added, mixed with an extruder having a diameter of 20 mm, and press-molded to obtain a molded product having a thickness of 1 mm. The molded product was immersed in a toluene solution of n-butyl titanate dissolved at a concentration of 10 g / liter to be impregnated and treated at 80 ° C. for 2 hours. The molding was then removed from the solution and treated at 120 ° C. for 3 hours. The 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 95%, and the weight increase of the molded product after extraction was only 15%.

The following physical properties of the molded product were measured. Flexural rigidity: kg / cm ² ASTM
D747 (23 ° C) Tensile yield strength: kg / cm ² ASTM
D638 (23 ° C) Izod (with notch) Impact strength: kg ・ cm / cm ASTM
D256 (20 ℃, -10 ℃) flexural modulus is 16500kg / cm ^2, the tensile yield strength is 320 kg / c
m ² , Izod impact strength 55 and 35 kgcm / cm respectively
Met.

Comparative Example 1 A molded and crosslinked product was molded and crosslinked in the same manner as in Example 1 without using polybutadiene.
Although it was not deformed even at 00 ° C., the ratio of the extraction residue extracted with boiling xylene for 12 hours was 94%, and the weight increase of the molded product after extraction was 95%. The physical properties of the molded product are as follows:
400 kg / cm ^2, the tensile yield strength is 405kg / cm ^2, an Izod impact strength was respectively 8, 2kg · cm / cm.

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. Η of the copolymer is 1.85 dl
/ G , melting point: 158 ° C., crystallization temperature: 115 ° C., extraction ratio with boiling n-heptane for 6 hours was 96.8%. Using 500 g of this powder, instead of polybutadiene, styrene butadiene rubber (manufactured by Zeon Corporation)
A molded article was prepared in the same manner as in Example 1 except that 100 g of Nipol 1507) 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 16000kg / cm
^2. Tensile yield strength was 310 kg / cm ² , and Izod impact strength was 65 and 41 kg · cm / cm, respectively. The molded product is 200
Even at ℃, there was no deformation, and the ratio of the extraction residue extracted with boiling xylene for 12 hours was 92%, and the weight increase of the molded product after extraction was only 35%.

Example 3 To 300 g of the copolymer obtained in Example 1 was added 100 g of polybutadiene (trade name: Nipol BR1220, manufactured by Nippon Zeon Co., Ltd.).
A pellet containing 10,000 ppm of a separately prepared rhodium chloride triphenylphosphine complex (commercially available isotactic polypropylene, manufactured by Mitsui Toatsu Chemicals, Inc., Mitsui Noblen JHH-G and rhodium chloride). Is produced by melting and mixing a triphenylphosphine complex of formula (1) at a ratio of 100: 1 and manufactured by Komatsu Ltd. (FKS5
5-1) A molded product was produced by the injection molding machine. This molded product
Heat treatment was performed at 155 ° C. for 2 hours. The physical properties of this molded product were as follows. Flexural rigidity is 17000 kg / cm ² , tensile yield strength is 320 kg / cm ² , Izod impact strength is 54,
It was 39 kg · cm / cm 2.

This molded product did not deform at all even at 200 ° C., and the ratio of the extraction residue extracted with boiling xylene for 12 hours was 99%.
% And the weight increase of the molded article after extraction was only 18%. In the case of the injection molded product, the ratio of the extraction residue extracted with boiling xylene for 12 hours was 35%, and there was no problem in molding.

Comparative Example 2 A molded and crosslinked product was molded and crosslinked in the same manner as in Example 1 without using polybutadiene.
Although it was not deformed even at 00 ° C., the ratio of the extraction residue extracted with boiling xylene for 12 hours was 94%, and the weight increase of the molded product after extraction was 95%. The physical properties of the molded product are as follows:
500 kg / cm ^2, the tensile yield strength is 415kg / cm ^2, an Izod impact strength was respectively 8,2kg · cm / cm.

Example 4 Using 500 g of the copolymer obtained in Example 2, instead of polybutadiene, styrene butadiene rubber (manufactured by Nippon Zeon Co., Ltd.)
A molded article was prepared in the same manner as in Example 3 except that 100 g of Nipol 1507) was used and treated in the same manner as in Example 3. The physical properties of the molded article were as follows. Flexural rigidity is 16300kg / cm
^2. Tensile yield strength was 330 kg / cm ² , and Izod impact strength was 62 and 45 kg · cm / cm, respectively.

The molded product does not deform at all even at 200 ° C.
The proportion of the extraction residue extracted with boiling xylene for 12 hours was 99%, and the weight increase of the molded product after extraction was only 16%.
In addition, the ratio of the extraction residue extracted with boiling xylene for 12 hours before the irradiation of γ-rays was 41%, and there was no problem in molding.

Example 5 The molded product obtained in Example 3 was further subjected to γ-ray irradiation at 5 Mrad / h at 1 Mrad.
After irradiation, the physical properties were measured and the flexural rigidity was 17100 kg /
cm ² , tensile yield strength was 340 kg / cm ² , and Izod impact strength was 52 and 38 kg · cm / cm, respectively.

This molded product does not deform at all even at 200 ° C.
The proportion of the extraction residue extracted with boiling xylene for 12 hours was 99%, and the weight increase of the molded product after extraction was only 12%.
In the case of the injection molded product, the ratio of the extraction residue extracted with boiling xylene for 12 hours was 35%, and there was no problem in molding.

Comparative Example 3 A molded and crosslinked product was molded and crosslinked in the same manner as in Example 5 without using polybutadiene.
Although it did not deform even at 00 ° C., the ratio of the extraction residue extracted with boiling xylene for 12 hours was 93%, and the weight increase of the molded product after extraction was 85%. In addition, the physical properties of the molded product have a flexural rigidity of 20.
000 kg / cm ² , tensile yield strength was 410 kg / cm ² , and Izod impact strength was 7.2 and 2 kg · cm / cm, respectively.

Example 6 The same as Example 5 except that 500 g of the copolymer powder obtained in Example 2 was used, and instead of polybutadiene, 100 g of styrene butadiene rubber (Nipol 1507, manufactured by Nippon Zeon Co., Ltd.) was used. A molded article was prepared and treated in the same manner as in Example 5, and the physical properties of the molded article were as follows. The flexural rigidity was 16200 kg / cm ² , the tensile yield strength was 320 kg / cm ² , and the Izod impact strength was 62 and 44 kg · cm / cm, respectively.

The molded product does not deform at all even at 200 ° C.
The ratio of the extraction residue extracted with boiling xylene for 12 hours was 98%, and the weight increase of the molded product after extraction was only 15%.
In addition, the ratio of the extraction residue extracted with boiling xylene for 12 hours before the irradiation of γ-rays was 41%, and there was no problem in molding.

[0049]

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.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification code FI C08L 9/00 C08L 9/00 23/00 23/00

Claims (4)

(57) [Claims] An alkenylsilane having a non-syndiotactic structure and a copolymer of an olefin and a polyalkadiene.
Rhodium salts and the following general formula (4) [of 4] (Wherein R ¹ and R ² are the same or different and have 1 to 12 carbon atoms)
A hydride residue, n is an integer of 0 to 3, M is titanium, zirconium
Metal selected from uranium and hafnium. ) Period
A crosslinked polyolefin molded product obtained by subjecting a catalyst selected from alkoxy compounds of Group IVB metals to contact treatment. 2. A molded article comprising a copolymer of alkenylsilane and olefin having no syndiotactic structure and polyalkadiene is prepared by adding a salt of rhodium and a compound represented by the following general formula : (Wherein R ¹ and R ² are the same or different and have 1 to 12 carbon atoms)
A hydride residue, n is an integer of 0 to 3, M is titanium, zirconium
Metal selected from uranium and hafnium. ) Period
A crosslinked polyolefin molded article obtained by contact treatment with a catalyst selected from alkoxy compounds of Group IVB metals . 3. A salt of a copolymer of alkenylsilane and olefin, a salt of polyalkadiene and rhodium and a compound represented by the following general formula:
6) [of 6] (Wherein R ¹ and R ² are the same or different and have 1 to 12 carbon atoms)
A hydride residue, n is an integer of 0 to 3, M is titanium, zirconium
Metal selected from uranium and hafnium. ) Period
A method for producing a crosslinked polyolefin molded article, comprising: subjecting a mixture comprising a catalyst selected from alkoxy compounds of Group IVB metals to heat-melt molding and heat-treating the mixture to a temperature not higher than the deformation temperature of the molded article. 4. A salt of a copolymer of alkenylsilane and olefin, a salt of polyalkadiene and rhodium and a compound represented by the following general formula:
7) [of 7] (Wherein R ¹ and R ² are the same or different and have 1 to 12 carbon atoms)
A hydride residue, n is an integer of 0 to 3, M is titanium, zirconium
Metal selected from uranium and hafnium. ) Period
A method for producing a crosslinked polyolefin molded article, which comprises subjecting a mixture comprising a catalyst selected from alkoxy compounds of Group IVB metals to heat-melt molding and then irradiating the molded article with radiation.