JPH05331303A - Production of cross-linked polyolefin molding - Google Patents

Abstract

PURPOSE:To easily obtain a cross.1inked polyolefin molding having excellent heat resistance by mixing an alkenylsilane/olefin copolymer with a compound having unsaturated bonds, molding the mixture, and exposing the molding to a radiation. CONSTITUTION:An alkenylsilane (e.g. vinylsilane) is copolymerized with an olefin (e.g. ethylene) by solution or bulk polymerization or other method using a catalyst which, for example, comprises a transition metal compound and an organometallic compound. The copolymer is mixed with a compound having at least two unsaturated bonds (e.g. divinylbenzene) and, according to need, with a filler (e.g. calcium carbonate). The mixture is molded, exposed to a radiation at 50 deg.C or lower, and then heated, if necessary, at a temp. between 100 deg.C and the heat distortion temp. of the molding, thereby giving the cross- linked polyolefin molding.

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 molding. Specifically, it relates to a method for producing a crosslinked molded article, which comprises irradiating a mixture of a specific copolymer and an unsaturated compound with radiation.

[0002]

2. Description of the Related Art Crosslinking of polyolefins has been widely carried out for the purpose of improving mechanical properties, solvent resistance, heat resistance and the like. Various methods have already been proposed as a method for crosslinking, and a method of mixing a bifunctional monomer and a radical generator and heating and melting, and a method of using a monomer having a hydrolyzable group such as alkoxysilane A method of polymerizing and molding, and then hydrolyzing with boiling water or the like to crosslink (JP-A-58-11724).
4) The method of cross-linking by irradiating radiation 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]

Although the heat resistance is considerably improved even when the crosslink density is small, 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 temperature. Is desired.

[0004]

[Means for Solving the Problems] The present inventors completed the present invention by earnestly studying a simple method for solving the above problems and increasing the crosslink density.

That is, the present invention is a method for producing a crosslinked polyolefin molded product, which comprises molding a mixture of an alkenylsilane / olefin copolymer and a compound having at least two unsaturated bonds and then irradiating the mixture with radiation. Is. Further, the present invention is directed to molding a mixture of a alkenylsilane / olefin copolymer and a compound having at least two unsaturated bonds, irradiating the mixture with radiation at a temperature of 50 ° C. or lower, and then deforming the molded product at a temperature of 100 ° C. or higher. The method for producing a crosslinked polyolefin molded article is characterized by comprising the following heat treatment.

In the present invention, as the alkenylsilane, those having at least one Si--H bond are preferably used. 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. Further, as the catalyst used for production, a catalyst composed of a transition metal compound and an organic metal compound is generally used, and a titanium halide is preferably used as the transition metal compound and an organic aluminum compound is preferably used as the organic metal compound.

Specifically, titanium trichloride obtained by reducing titanium tetrachloride with metallic aluminum, hydrogen or organoaluminum, modified with an electron-donating compound, an organoaluminum compound, and optionally an oxygen-containing organic compound. Such as a catalyst system comprising an electron donating compound, or 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 compound such as ester and ether if necessary, then Examples include a catalyst system comprising a transition metal compound catalyst obtained by a method of treatment with titanium rogenide and an organoaluminum compound, and optionally an electron-donating compound such as an oxygen-containing organic compound (for example, various publications listed 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, and 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 polymer obtained by reacting the above organoaluminum with water or water of crystallization can also be used.

The alkenylsilane and the olefin are polymerized in a proportion of 0.1 to 30 mol%, preferably 0.1 to 30 mol%, in order to increase the degree of crosslinking.
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 deteriorates, so 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 onto 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 of grafting alkenylsilane to, and the method and conditions used for ordinary graft copolymerization can be used. Normally, the polyolefin and alkenylsilane used are radical initiators in the presence of a radical initiator such as peroxide. Graft copolymerization can be easily carried out by heating above the decomposition temperature of.

In the present invention, the polyolefin used as a mixture with the above-mentioned copolymer, if necessary, is an olefin represented by the general formula (Formula 2), specifically ethylene, propylene, butene-1, pentene-1, hexene. -1,2-methylpentene, heptene-1, octene-1, and other α-olefins, or homopolymers of styrene or its derivatives,
Random copolymers with each other, or first with olefins alone or with small amounts of other olefins, then 2
Examples include so-called block copolymers produced by copolymerizing at least one olefin.

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 above-mentioned method for producing a copolymer of olefin and alkenylsilane except that alkenylsilane is not used.

In the present invention, the compound containing at least two unsaturated bonds is, as the compound containing a reactive unsaturated bond, an aromatic vinyl compound such as divinylbenzene, diisopropenylbenzene or diallylbenzene, ethylene glycol diethylene. Examples thereof include unsaturated esters such as methacrylate and ethylene glycol diacrylate, polymers such as polybutadiene and polyisoprene, and any compound can be used as long as it has at least two reactive unsaturated bonds.

The ratio of the compound having at least two unsaturated bonds to the alkenylsilane / olefin copolymer is usually 0.01 to 10 parts by weight, preferably 100 to 100 parts by weight of the alkenylsilane / olefin copolymer. It is 0.1 to 5 parts by weight. If it is less than this, the improvement effect is small, and if it is more than this, unreacted unsaturated compounds increase, which is not preferable.

In the present invention, it is possible to use a filler together if necessary. As the filler, any filler can be used as long as it is a filler used for improving the physical properties of polyolefin, but usually a salt of a metal or an oxide is used. A material having a large reinforcing effect such as a needle-shaped material, a nitride-shaped material, a carbide-shaped material, a scale-shaped material, or a fibrous material is preferably used. Specifically, talc, kaolin, mica,
Calcium carbonate, calcium silicate, calcium sulfate, calcium sulfite, barium titanate, etc. can be used.
Copolymer of filler, alkenylsilane and olefin,
From the viewpoint of physical properties, it is preferable to mix a compound having at least two unsaturated bonds and, if necessary, a polyolefin to form a mixture, and to make the content of the filler in the whole composition 0 to 60 wt%.

The above-mentioned alkenylsilane / olefin copolymer, a compound having at least two unsaturated bonds, a filler to be mixed if necessary, or a method for mixing the polyolefin is not particularly limited and may be powdered in a usual manner. It is mixed and used as it is, or melt-kneaded and granulated. Prior to irradiation with the radiation described below, it is molded by injection molding, extrusion molding, press molding, or the like. When the alkenylsilane concentration in the mixture is 0.01 to 20 mol%, preferably 0.1 to 10 mol%, a crosslinked polyolefin having a high crosslinking concentration can be obtained.

In the present invention, radiation means electron beam, γ
Lines, X-rays, ultraviolet rays, etc. are exemplified. Irradiation is performed after forming a desired molded product from a mixture of the above-mentioned alkenylsilane copolymer and a compound containing at least two unsaturated bonds. The irradiation dose is usually 0.1 to 100M
It is about rad, preferably about 1 to 50 Mrad. The irradiation temperature may be below the deformation temperature of the molded product, and is generally 0 ° C to the deformation temperature of the molded product, preferably 50 ° C.
It is below ℃.

In the present invention, the molded product irradiated with the above-mentioned radiation is optionally heat-treated. The heating temperature is usually 100 ° C to the deformation temperature of the molded product or less because the heating time is shorter as long as the molded product is not deformed, so that the heating treatment time is shorter. The heating time is about several minutes to several tens of hours.

[0026]

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 pressure injection, 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 180 g of powder.

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

Divinylbenzene was added to 100 g of the obtained copolymer.
5 g was mixed and press-molded to obtain a molded product having a thickness of 1 mm. This molded product was irradiated with γ-rays at 5 Mrad at room temperature. The molded product was not deformed at 200 ° C. at all, the extraction residue ratio after extraction for 12 hours with boiling xylene was 99%, and the weight increase of the molded product after extraction was only 12%.

Comparative Example 1 The same molding was carried out without using divinylbenzene and crosslinked by irradiating with γ-ray. When the molding was not deformed even at 200 ° C., it was heated in boiling xylene for 12 hours. The percentage of the extracted residue was 91%, and the weight increase of the molded product after extraction was 105%.

Example 2 Divinylbenzene 5 was added to 100 g of the copolymer obtained in Example 1.
g and 30 g of talc (CT-8 manufactured by Asada Flour Milling Co., Ltd.) were mixed and press-molded to obtain a molded product having a thickness of 1 mm. In this molded product
Irradiation with 5 Mrad γ-rays was performed at 30 ° C and 3.2 Mrad / h. This molded product was not deformed at 200 ° C. at all, the extraction residue ratio extracted with boiling xylene for 12 hours was 98%, and the weight increase of the molded product after extraction was only 9%. The following physical properties of the molded product were measured. Flexural rigidity: 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 ℃, − Bending rigidity is 20600kg / cm ² , tensile yield strength is 410kg / c
m ² and Izod impact strength is 8 and 2 kg ・ cm / cm ² respectively
Met.

Comparative Example 2 The same molding as in Example 2 except that divinylbenzene was not used and irradiation with γ-rays and crosslinking were evaluated in the same manner. The molding did not deform even at 200 ° C. 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 105%. The physical properties of the molded product are a flexural rigidity of 20000 kg / cm ² and a tensile yield strength of 400 k.
g / cm ² , Izod impact strength is 8, 2 kg · cm / c respectively
It was m ² .

Example 3 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 2 except that 100 g of this powder was used, and was treated in the same manner as in Example 1. The physical properties of the molded product were as follows. Flexural rigidity 19600kg /
cm ² , tensile yield strength was 385 kg / cm ² , and Izod impact strength was 10 and ² kg · cm / cm ² , respectively. In addition, the molded product is
It was not deformed at 200 ℃ at all, 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 25%.

Example 4 Divinylbenzene 5 was added to 100 g of the copolymer obtained in Example 1.
g and talc (CT-8 manufactured by Asada Flour Milling Co., Ltd.)
Press molding was performed at 250 ° C. to obtain a molded product having a thickness of 1 mm. This molded article was irradiated with 3 Mrad γ rays at 30 ° C. and 3.2 Mrad / h.
The molded product was not deformed even at 200 ° C., and the ratio of the extraction residue extracted by boiling xylene for 12 hours was 96%, and the weight increase after extraction was 45%. When this molded product was subjected to heat treatment at 130 ° C. for 2 hours, the ratio of the extraction residue extracted with boiling xylene for 12 hours was 99%, and the weight increase after extraction was 11%.
The physical properties of the molded product were as follows. Bending rigidity is 20700 kg / cm ² before heat treatment and 21800 kg / c after heat treatment
m ^2, tensile yield strength before heat treatment is 400 kg / cm ^2, after heat treatment is 410 kg / cm ^2, an Izod impact strength, respectively before the heat treatment 10,2.5kg · cm / cm ^2, change after the heat treatment There was no.

Comparative Example 3 The same molding as in Example 1 without using divinylbenzene and irradiation with γ-rays for crosslinking was evaluated in the same manner. The molding did not deform even at 200 ° C., but boiled. The ratio of the extraction residue extracted with xylene for 12 hours was 88%, and the increase in the weight of the molded product after extraction could not be measured. As for the physical properties of the molded product, the bending rigidity is 20000 kg / cm ² , and the tensile yield strength is 390 k.
g / cm ² , Izod impact strength is 9.5, 2.5 kg
It was cm / cm ² .

Example 5 The same procedure as in Example 4 except that the copolymer obtained in Example 3 was used, and the physical properties of the molded product were as follows. The flexural rigidity was 19,800 kg / cm ² , the tensile yield strength was 390 kg / cm ² , and the Izod impact strength was 12, 2.5 kg · cm / cm ² , respectively. The molded product was not deformed at 200 ° C. at all, the extraction residue ratio after extraction with boiling xylene for 12 hours was 96%, and the weight increase of the molded product after extraction was only 25%.

[0038]

EFFECTS OF THE INVENTION By carrying out the method of the present invention, a heat resistant crosslinked molded article can be easily obtained, which is extremely valuable industrially.

Claims (3)

[Claims] 1. A method for producing a crosslinked polyolefin molded article, which comprises irradiating radiation after molding a mixture of an alkenylsilane / olefin copolymer and a compound having at least two unsaturated bonds. 2. A method for producing a crosslinked polyolefin molded article, which comprises irradiating radiation after molding a mixture of an alkenylsilane / olefin copolymer, a compound having at least two unsaturated bonds and a filler. 3. A mixture of an alkenylsilane / olefin copolymer and a compound containing at least two unsaturated bonds is molded, irradiated with radiation at a temperature of 50 ° C. or lower, and then deformed at 100 ° C. or higher. A method for producing a crosslinked polyolefin molded article, which comprises performing heat treatment at a temperature of not higher than a temperature.