JPH04337336A - Electrically conductive polyolefin resin molding and production thereof - Google Patents

Abstract

PURPOSE:To obtain the subject electrically conductive molding excellent in heat resistance by blending an electrically conductive carbon with a copolymer of an alkenylsilane and an olefin. CONSTITUTION:A mixture prepared by blending 5-90wt.%, preferably 10-80wt.% electrically conductive carbon (e.g. carbon black) with a copolymer of an alkenylsilane (e.g. vinylsilane or allylsilane) and an olefin (e.g. ethylene or propylene) is molded to obtain a molding containing boiling xylene insoluble matters in a larger quantity than that of the electrically conductive carbon. Radioactive rays (e.g. gamma ray or X ray) are then applied to the resultant molding.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to conductive polyolefin resin molded articles. Specifically, the present invention relates to a crosslinked conductive polyolefin resin molded product and a method for producing the same.

0002

[Prior Art] It is widely practiced to impart conductivity to polyolefin molded products by mixing conductive carbon into them, and conductive polyolefin molded products are used for a variety of purposes, including as heating elements. has recently begun to be used.

0003

[Problems to be Solved by the Invention] However, polyolefins have a relatively low melting point and cannot withstand use at high temperatures.To solve this problem, crosslinking is considered, but with water crosslinking, the There is a problem in that the electrical conductivity of the molded product is poor, and in the case of ordinary polyolefins, there is a problem in that it is necessary to increase the radiation dose in order to obtain a sufficient degree of crosslinking by radiation irradiation.

0004

[Means for Solving the Problems] The present inventors have conducted extensive research into a conductive polyolefin resin molded product with excellent heat resistance that solves the above-mentioned problems, and have completed the present invention.

That is, the present invention is a conductive polyolefin resin molded product comprising a mixture of a copolymer of alkenylsilane and olefin and conductive carbon, in which the content insoluble in boiling xylene is greater than the content of the conductive carbon, Further, the present invention is a preferred method for producing the same, which is a method for producing a conductive polyolefin resin molded product, which comprises irradiating a molded product made of a mixture of an alkenylsilane and olefin copolymer and conductive carbon with radiation. .

The molded product of the present invention will be explained in detail by showing an example of its manufacturing method. In the present invention, the copolymer of alkenylsilane and olefin is usually produced by polymerizing olefin and alkenylsilane using a so-called Ziegler-Natta catalyst consisting of a transition metal catalyst and an organometallic compound. 68
An example is disclosed in No. 6. Furthermore, a graft copolymer obtained by graft polymerizing a polyolefin by heat-treating it with alkenylsilane in the presence of a radical polymerization initiator such as peroxide may also be used.

As the alkenylsilane, those having at least one Si-H bond are preferably used, such as compounds represented by the following general formula (Formula 1),

0008
]

[Chemical formula 1] H2C=CH-(CH2)n-SiHPR3-
P (in the formula, n is 0 to 12, p is 1 to 3, R is carbon number 1 to
12 hydrocarbon residues. ), and specific examples include vinylsilane, allylsilane, butenylsilane, pentenylsilane, and compounds in which H in the Si-H bond of some of these monomers is replaced with chloro.

In addition, as an olefin, the following general formula (Chemical formula 2
),

0010

[Chemical formula 2] H2C=CH-R (In the formula, R is a hydrocarbon residue having 1 to 12 carbon atoms.) Specific examples include ethylene, propylene, butene-1
, pentene-1, hexene-1,2-methylpentene,
In addition to α-olefins such as heptene-1 and octene-1, styrene or derivatives thereof are also exemplified.

In the present invention, the copolymer of olefin and alkenylsilane is TiC, which is described in the above US patent.
A catalyst consisting of 13 and triethylaluminum can also be used, but it is more preferable to use various highly active catalysts that have been developed since then and which give polyolefins.

As the polymerization method, in addition to the solvent method using an inert solvent, bulk polymerization method and gas phase polymerization method can also be employed.

As the catalyst comprising a transition metal compound and an organometallic compound, a titanium halide is preferably used as the transition metal compound, and an organoaluminum compound is preferably used as the organometallic compound.

For example, titanium tetrachloride can be replaced with metallic aluminum,
A catalyst system consisting of titanium trichloride obtained by reducing with hydrogen or organoaluminum and modified with an electron-donating compound, an organoaluminium compound, and an electron-donating compound such as an oxygen-containing organic compound as necessary, or a halogenated A catalyst consisting of a transition metal compound catalyst obtained by supporting titanium halide on a carrier such as magnesium or a carrier treated with an electron-donating compound, an organoaluminum compound, and an electron-donating compound such as an oxygen-containing organic compound if necessary. system, or a reaction product of magnesium chloride and alcohol is dissolved in a hydrocarbon solvent, and then treated with a precipitant such as titanium tetrachloride to make it insolubilized in the hydrocarbon solvent. Examples include a catalyst system consisting of a transition metal compound catalyst obtained by a method of treating with a compound of For example, various examples are described in the following documents: Ziegler-Na
tta Catalysts and Polymer
ization by John Boor Jr.
Academic Press), Journal of
Macromolecular Science R
views in Macromolecular
Chemistry and Physics,C24
(3) 355-385 (1984), C25 (1
) 578-597 (1985)).

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

[0016] As the electron-donating compound, oxygen-containing compounds such as ether, ester, orthoester, and alkoxy silicon compound are generally preferred, and alcohol, aldehyde, water, etc. can also be used.

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

There is no particular restriction on the polymerization ratio of alkenylsilane and olefin, but when used in combination with polyolefin, alkenylsilane is usually 0.0%.
The amount is about 0.001 to 30 mol%, preferably 0.1 to 10 mol%. In addition, when used alone, 0.0001~
It is about 1 mol%.

There is no particular restriction on the molecular weight of the polymer, but when it is intended to improve the physical properties by mixing it, it is preferable that the molecular weight is about the same as or lower than that of the polyolefin.

[0020] Depending on the case, it may be used by carrying out the same polymerization as polyolefins (composition, molecular weight, etc.) except that it contains alkenylsilane. For example, block copolymerization may be carried out and alkenylsilane is added only in the first stage or only in the second stage. may be copolymerized. The preferred molecular weight is 135
Intrinsic viscosity measured in tetralin solution at °C is 0.1 to 1
It is about 0.

[0021] A graft copolymer obtained by graft polymerizing an alkenylsilane to a polyolefin (for example, the following polyolefins can be used as a mixture) can also be used for the purpose of the present invention; in that case, the polyolefin There are no particular restrictions on the method of grafting alkenylsilane to the polymer, and the methods and conditions used for normal graft copolymerization can be used, and the method usually involves heating above the decomposition temperature of the radical initiator in the presence of the polyolefin and alkenylsilane used. can be easily graft copolymerized.

[0022] In the present invention, the polyolefin used in combination with the above-mentioned copolymer as required is an olefin represented by the above general formula (Chemical formula 2), specifically ethylene, propylene, butene-1, pentene-1, hexene. -1, 2
- homopolymers of α-olefins such as methylpentene, heptene-1, octene-1, or styrene or its derivatives, random copolymers of each other, or olefins initially alone or copolymerized with small amounts of other olefins; Examples include so-called block copolymers produced by then copolymerizing two or more types of olefins.

It is particularly effective to use poly-α-olefins such as polypropylene or copolymers thereof, which are difficult to crosslink when used alone. Methods for producing these polyolefins are already known, and various brands are available on the market.

It can also be produced in the same manner as the above-mentioned method for producing a copolymer of olefin and alkenylsilane, except that alkenylsilane is not used.

[0025] In the present invention, conductive carbon may be any carbonaceous substance that can impart high conductivity when mixed with it, and includes natural graphite, artificial graphite, carbon black, carbon fiber, etc. Carbon blacks such as , furnace black, and acetylene black are preferred. Its usage rate is 5 to 90 wt%, preferably 10 to 80 wt% of the total molded product. If it is less than this, the conductivity will be poor, and if it is more than this, the physical properties will be poor.

[0026] In the present invention, the boiling xylene insoluble matter is
The extracted residue when the molded product was placed in a 400 mesh wire mesh and extracted with boiling xylene for 12 hours is shown, and the degree of crosslinking of the molded product is shown. The content thereof is preferably greater than the amount of conductive carbon used, and is preferably at least 30% by weight, particularly at least 50% by weight of the molded product.

In the present invention, other additives such as stabilizers, fillers, and various other known additives can also be used.

In the present invention, prior to irradiation with the radiation described below, a copolymer of alkenylsilane and olefin,
The conductive carbon is mixed with polyolefin or additives as necessary to form a composition, which is then formed into a sheet or film, and then irradiated with radiation.

In the present invention, examples of radiation include gamma rays, electron beams, X-rays, accelerated ions, etc., but gamma rays and It is preferable to thin the object and irradiate it. A dose of 0.1 to 50 Mrad, usually about 1 to 10 Mrad, is sufficient for irradiation.

The alkenylsilane content in the molded article depends on the alkenylsilane content in the copolymer, but usually the proportion of the copolymer in the molded article is 0.1 wt% or more, and the alkenylsilane content in the molded article is is preferably present in an amount of 0.0001 wt% or more. In addition, from the viewpoint of moldability or reducing the amount of expensive alkenylsilane used, 5.0 wt% or less is sufficient, and preferably 0.1 to 2.0 wt% as alkenylsilane in the molded product.
It is about %.

[0031]

[Examples] The present invention will be further explained by showing examples below.

Example 1 A vibratory mill equipped with four grinding pots each having an internal volume of 4 liters each containing 9 kg of steel balls each having a diameter of 12 mm was prepared. 300 g of magnesium chloride, 60 ml of tetraethoxysilane and 45 ml of α, α, α-trichlorotoluene were placed in each pot under a nitrogen atmosphere, and the mixture was ground for 40 hours. 300 g of the thus obtained co-pulverized product was placed in a 5 liter flask, 1.5 liters of titanium tetrachloride and 1.5 liters of toluene were added, stirred at 100° C. for 30 minutes, and then the supernatant liquid was removed. Titanium tetrachloride again 1.
Add 5 liters and 1.5 liters of toluene,
The mixture was stirred at 00°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 we sampled a portion and analyzed the titanium content, the titanium content was 1.9 wt%.

In an autoclave with an internal volume of 5 liters, 40 ml of toluene and 100 ml of the above transition metal catalyst were placed in a nitrogen atmosphere.
mg, diethylaluminum chloride 0.128
ml, 0.06 ml of methyl p-toluate and 0.20 ml of triethylaluminum, and 1.0 ml of propylene.
After adding 5 kg of vinylsilane and 40 g of vinylsilane and pressurizing 1N liter of hydrogen, polymerization was carried out at 75°C for 2 hours. After polymerization, unreacted propylene was purged, and the powder was taken out and filtered and dried to obtain 180 g of powder.

[0034] Intrinsic viscosity (hereinafter abbreviated as η) measured with a tetralin solution at 135 °C, melting point and crystallization temperature measured as maximum peak temperature by increasing or decreasing temperature at 10 °C/min using a differential thermal analyzer. Then,
The obtained powder has an η of 1.72 and a melting point of 153
It was a crystalline propylene copolymer with a crystallization temperature of 118°C. According to elemental analysis, it contained 1.2 wt% of vinylsilane units.

To 400 g of the obtained copolymer, 100 g of Furnace Black (trade name: Ketjen Black EC) manufactured by Ketjen Black International Co., Ltd. was added, and 2,6-di-t-butyl-4-methylphenol 1.
Add 0g and mix well, then use a 20mm extruder to
Granulation was carried out at 0°C. It was then injection molded into a 1 mm thick sheet.

When this sheet was irradiated with a 750 keV electron beam at 3 Mrad at room temperature and extracted with boiling xylene for 12 hours, the insoluble content was 85.1 wt% and did not deform at 200°C. In contrast, the sheet before being irradiated with the electron beam was deformed. Specific resistance is 2.9×104Ω・cm before irradiation
On the other hand, there was almost no change to 2.5×10 4 Ω·cm after irradiation.

[0037]

[Effects of the Invention] The molded product of the present invention can be used as a conductive molded product with excellent heat resistance and is extremely valuable industrially.

Claims (2)

[Claims] 1. A conductive polyolefin resin molded product comprising a mixture of an alkenylsilane and olefin copolymer and conductive carbon, the molded product having a boiling xylene insoluble content greater than the content of the conductive carbon. 2. A method for producing a conductive polyolefin resin molded article, which comprises irradiating a molded article made of a mixture of an alkenylsilane and olefin copolymer and conductive carbon with radiation.