JPH0550500A - Manufacture of crosslinked molding made of polypropylene - Google Patents

Abstract

PURPOSE:To simply obtain a crosslinked stretched molding made of propylene by stretching a molding obtained by subjecting a propylene/alkenylsilane copolymer to melt molding at least in one direction within a solution containing a transition metal compound. CONSTITUTION:An alkenylsilane/propylene copolymer is mixed with polypropylene or additives if necessary to prepare a composition which is, in turn, subjected to melt molding to form a sheet or film. This molding is heated in a transition metal compound solution if necessary to be stretched at least in one direction. As the transition metal compound, a compound of a group IV, VIII-X metal of the Periodic Table, especially, halide of rhodium or platinum or an alkoxy compound of titanium or zirconium is pref. and the concn. of the solution is about 0.000001-1g/l. The concn. of alkenylsilane in the molding is pref. about 0.0001-1.0wt.%. As alkenylsilane, one having at least one Si-H bond is pref.

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 molded article of polypropylene. More specifically, the present invention relates to a method for producing a polypropylene cross-linked molded product, which comprises stretching a specific copolymer molded product in a catalyst solution.

[0002]

2. Description of the Related Art A method using a copolymer of propylene and an alkenylsilane is excellent as a method for producing a crosslinked molded article of polypropylene, and a method of crosslinking using a catalyst is particularly efficient.

[0003]

The method of crosslinking a copolymer by using a catalyst is an efficient and excellent method.
There is a problem that there are many steps such as molding, stretching and contact treatment.

[0004]

[Means for Solving the Problems] The present inventors completed the present invention by earnestly investigating a method for solving the above-mentioned problems and producing a stretch-molded article of easily crosslinked polypropylene.

That is, the present invention is characterized in that a molded product obtained by melt-molding a copolymer of propylene and alkenylsilane is stretched in at least one direction in a solution containing a transition metal compound, thereby forming a polypropylene by crosslinking. It is a method of manufacturing a product.

In the present invention, the copolymer of alkenylsilane and propylene can be usually obtained by polymerizing propylene and alkenylsilane using a so-called Ziegler-Natta catalyst composed of a transition metal catalyst and an organometallic compound.
An example is disclosed in US Pat. No. 3,223,686.

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),

[0008]

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.

In the present invention, it is also possible to use a copolymer obtained by copolymerizing a part of propylene with another olefin, and as the other olefin, ethylene, butene-1, pentene-1, hexene-1, 2 can be used. -Methylpentene, Heptene-
1, octene-1, etc. are exemplified, and those copolymerized so as to be less than 10 wt% of the total polymer can be used.

In the present invention, the copolymer of propylene and alkenylsilane is the TiCl ₃ polymer described in the above-mentioned US patent.
It is also possible to use a catalyst composed of a triethylaluminum and triethylaluminum, but more preferably, various subsequently developed catalysts which give polyolefins with high activity are used.

As the polymerization method, in addition to the solvent method using an inert solvent, a bulk polymerization method or a gas phase polymerization method can be adopted.

As the catalyst composed of 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 is used for metallic aluminum,
Titanium trichloride obtained by reduction with hydrogen or organoaluminum, modified with an electron donating compound, an organoaluminum compound, and optionally a catalyst system comprising an electron donating compound such as an oxygen-containing organic compound, or halogenation A catalyst comprising an electron-donating compound such as a transition metal compound catalyst obtained by supporting a titanium halide on a carrier such as magnesium or treated with an electron-donating compound and an organoaluminum compound, and optionally an oxygen-containing organic compound. System, or the reaction product of magnesium chloride and alcohol, is dissolved in a hydrocarbon solvent and then treated with a precipitating agent such as titanium tetrachloride to make it insoluble in the hydrocarbon solvent, and if necessary, electron donating properties such as ester and ether. Transition obtained by the method of treating with a compound of Group compound catalyst and an organoaluminum compound, the catalyst system and the like formed of an electron-donating compound such as oxygen-containing organic compound optionally (e.g., following various examples in the literature are described .Ziegler-Natta Cataly
sts and Polymerization by John Boor Jr (Academic Pr
ess), Journal of Macromorecular Science Reviews in
Macromolecular Chemistry and Physics, C24 (3) 355-38
5 (1984), C25 (1) 578-597 (1985)).

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

Here, the polymerization ratio of alkenylsilane and propylene is not particularly limited, but when mixed with polypropylene, alkenylsilane is usually 0.001
It is about 30 to 30 mol%, preferably 0.1 to 10 mol%. When used alone, it is about 0.0001 to 1 mol%.

The molecular weight of the polymer is not particularly limited, but when it is intended to improve the physical properties by mixing, it is preferable that the molecular weight is the same as or lower than the molecular weight of polypropylene to be mixed and used. Also, as a preferable molecular weight
The intrinsic viscosity measured with a tetralin solution at 135 ° C is 0.1 to 10
It is a degree.

In the present invention, as a polypropylene to be mixed with the above-mentioned copolymer, if necessary, a homopolymer of propylene and a copolymer of less than 10 wt% of the above-mentioned other olefin can be used. The coalesced can also be obtained on the market.

In the present invention, various known additives such as stabilizers and fillers can be used in addition to polypropylene as the additive used by mixing with the copolymer of alkenylsilane and propylene.

In the present invention, a copolymer of alkenylsilane and propylene is mixed with polypropylene or an additive as required to form a composition prior to contact with a catalyst to be described later, and then melt-molded into a sheet or film. It The conditions for producing this sheet or film are not limited, but usually 10 to 10
It is assumed to be a molded product of 1000 μm.

In the present invention, the molded product is then stretched in the transition metal compound solution in at least one direction. Here, the transition metal compound is a group 4 or 8 of the periodic table.
Compounds of metals of groups 9, 9 and 10 can be preferably used,
In particular, a halide of rhodium or platinum, or an alkoxy compound of titanium or zirconium can be preferably used.

The above catalyst is used by dissolving it in the following solvent and diluting it. As the solvent used, specifically, a hydrocarbon compound having 1 to 20 carbon atoms and a halogenated hydrocarbon compound can be used, and particularly, a halogenated hydrocarbon compound and an aromatic hydrocarbon compound are preferably used. Specific examples include benzene, toluene, xylene, ethylbenzene, dichloromethane, chloroform, dichloroethane, trichloroethane, perchloroethane and the like.

In the present invention, the catalyst concentration is 0.0000.
It is carried out at about 01 to 1 g / liter, usually about 0.00001 to 0.1 g / liter.

In the present invention, the above-mentioned sheet or film is dipped in a catalyst solution and, if necessary, heated and stretched.

In the present invention, the time used for stretching is
Conditions at the time of contact, for example, the concentration of the catalyst, the temperature of the catalyst solution,
Although the time required for crosslinking varies depending on the shape of the copolymer, the concentration of alkenylsilane in the copolymer, etc., it is not specified, but the crosslinking is completed at the same time as the stretching is completed or the annealing is completed after the stretching. Should be set to The stretching temperature is usually from the melting point to room temperature, preferably from 50 to 165 ° C. At this time, it is of course possible to stir to assist the dispersion of the catalyst.

The content of alkenylsilane in the preferable film depends on the content of alkenylsilane in the copolymer, but the proportion of the copolymer in the molded product is usually 0.1 wt% or more. It is preferred that the silane be present in an amount of 0.0001 wt% or more. From the viewpoint of moldability or reduction of the amount of expensive alkenylsilane used, 1.0 wt% or less is sufficient, and the alkenylsilane in the molded product is preferably about 0.0001 to 1.0 wt%.

[0028]

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. Under a nitrogen atmosphere, 300 g of magnesium chloride, 112 ml of diisobutyl phthalate and 60 ml of titanium tetrachloride were placed in each pot and pulverized for 40 hours. 300 g of the co-ground product thus obtained was placed in a 5 liter flask, 3 liters of toluene were added, and 110 ° C
After stirring for 30 minutes, the supernatant was removed. Toluene (3 liters) was added again, the mixture was stirred at 80 ° 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 2.2 wt.
%Met.

In an autoclave having an internal volume of 5 liters, 40 ml of toluene, 100 mg of the above transition metal catalyst, 0.1 ml of dimethylcyclohexyldimethoxysilane and 0.20 ml of triethylaluminum were placed in a nitrogen atmosphere, 1.5 kg of propylene,
After adding 40g of vinyl silane and pressurizing 1N liter of hydrogen,
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 890 g of powder. The same reaction was repeated to obtain about 2.5 kg of polymer.

The intrinsic viscosity of this polymer measured with a tetralin solution at 135 ° C. was 1.68, and the melting point and the crystallization temperature were raised to the maximum peak temperature by raising or lowering the temperature at 10 ° C./min using a differential thermal analyzer. The melting point was 159 ° C and the crystallization temperature was 119 ° C. According to elemental analysis, the vinylsilane unit content was 1.1 wt%.

To 100 parts by weight of this polymer, 0.1 part by weight of a phenolic antioxidant and 0.1 part of calcium stearate are added.
After adding parts by weight and mixing with a Henschel mixer, the L / D
Pelletized at 240 ° C. using a 22 20 mmφ extruder. Using the pellets, a 700 μm-thick sheet was obtained through a T-die at 240 ° C. using the same extruder. This sheet is n-
5 ml of butyl titanate was immersed in a solution of 1 liter of toluene and stretched at 150 ° C with a stretching machine (TM-LOMG) 5 times in MD and 7 times in TD to obtain a stretched film having a thickness of 15 µm. ..

The physical properties of the obtained film were measured and the results were as follows. Young's modulus (ASTM D882, Kg / mm ² ) 23
5, tensile strength (ASTM D638, Kg / mm ² ) is 21.3, breakdown voltage
(ASTM D149, V / μ) is 498 at 25 ° C, 490 at 80 ° C, 120 ° C
It was 455 and the boiling xylene insoluble content was 98%.

Comparative Example 1 Example 1 was repeated except that after stretching, the catalyst was contacted with the catalyst for crosslinking.
Same as above, Young's modulus 228, tensile strength 18.5,
Breakdown voltage is 498 at 25 ° C, 484 at 80 ° C, 435 at 120 ° C.
The boiling xylene insoluble content was 92%.

Comparative Example 2 In Comparative Example 1, the physical properties were measured as they were without contacting the catalyst. Young's modulus was 227, tensile strength was 16.0, dielectric breakdown voltage was 505 at 25 ° C, 474 at 80 ° C, 415 at 120 ° C. Met.

Example 2 The same procedure as in Example 1 was carried out except that rhodium chloride triphenylphosphine complex was used instead of n-butyl titanate. Young's modulus was 238, tensile strength was 24.0, and breakdown voltage was
It was 498 at 25 ° C, 485 at 80 ° C and 465 at 120 ° C.

[0037]

INDUSTRIAL APPLICABILITY By the method of the present invention, a crosslinked stretch-molded product can be easily obtained and is industrially extremely valuable.

Claims (1)

[Claims] 1. A method for producing a crosslinked molded article of polypropylene, characterized in that the molded article obtained by melt-molding a copolymer of propylene and alkenylsilane is stretched in at least one direction in a solution containing a transition metal compound. Method.