JPH05310970A - Production of cross-linked polyolefin moldings - Google Patents

Abstract

PURPOSE:To obtain the title functional moldings having cross-link density different according to the places by dipping moldings comprising an alkenylsilane and olefin copolymer and a polysilicone containing Si-H groups in a catalyst solution treating them with heat. CONSTITUTION:A copolymer prepared by copolymerization of an alkenyl silane such as vinylsilane and an olefin such as propylene using a polymerization catalyst containing a transition metal compound such as a titanium halide and an organometallic compound such as an organoaluminum compound is mixed with a polysilicone containing Si-H groups such as polyphenylsilicone and formed, for example, by press molding. The resulting moldings are brought into contact with a catalyst solution of a catalyst such as titanium tetrabutoxide in toluene so that catalyst may not penetrate inside homogeneously. Then, the resulting moldings are heat-treated to give functional polyolefin moldings ware heterogeneously cross-linked and different in cross-link density according to the places.

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. More specifically, it relates to a method for producing a crosslinked polyolefin molded product obtained by treating a molded product composed of a specific copolymer and polysilicone with a catalyst by a specific method to heterogeneously crosslink.

[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 by using a crosslinked molded article as a structure or by improving the solvent resistance at high temperature. Further, depending on the use, it is required that the molded product has a partially different crosslink density than that of the entire molded product which is uniformly crosslinked.

[0004]

Means for Solving the Problems The inventors of the present invention have intensively studied a method for solving the above problems and producing a simple crosslinked polyolefin molded product having a gradient in crosslink density, and completed the present invention.

That is, according to the present invention, a molded article composed of a copolymer of alkenylsilane and olefin and a poly-silicone containing Si--H groups is contacted with a catalyst solution so that the catalyst does not uniformly penetrate to the inside, and then the catalyst is contacted. It is a method for producing a crosslinked polyolefin molded article that has been crosslinked nonuniformly, which is characterized in that it is taken out of the solution and heat-treated.

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. Therefore, 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 following polyolefins may be mixed and used, if desired. The polyolefin used as a mixture with the above copolymer, if necessary, is an olefin represented by the above general formula (formula 2), specifically ethylene, propylene, butene-1, pentene-1, hexene.
-1,2-methylpentene, heptene-1, octene-1, and other α-olefins, homopolymers of styrene or its derivatives, mutual random copolymers, or olefins alone, or small amounts of other Examples thereof include so-called block copolymers produced by copolymerizing with an olefin and then copolymerizing two or more kinds of olefins.

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, examples of the poly-silicone containing a Si--H group include compounds represented by the following general formula (Formula 3).

[0021]

[Chemical 3] (In the formula, R is a hydrocarbon residue having 1 to 20 carbon atoms, and n is an integer of 1 or more.).

Such a compound can be produced by hydrolyzing the corresponding alkyldichlorosilane represented by the following general formula (Formula 4) or allyldichlorosilane with water.

[0023]

Embedded image RSiCl ₂ (wherein R is a hydrocarbon residue having 1 to 20 carbon atoms).

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

The method of mixing the above-mentioned alkenylsilane / olefin copolymer, polysilicone and, if necessary, the polyolefin to be mixed is not particularly limited, and they are mixed in a powder state by a conventional method and used as they are, or further melt-kneaded. Granulated. Molding is performed prior to contact with the catalyst described below. Examples of the molding method include injection molding, extrusion molding and press molding. When the alkenylsilane concentration in the mixture is 0.01 to 20 mol%, preferably 0.1 to 10 mol%, a crosslinked polyolefin molded product having a high concentration of crosslinking points can be obtained.

In the present invention, as the catalyst, a rhodium salt such as a triphenylphosphine complex of rhodium chloride, or an alkoxy compound of a metal of Group IVB of the periodic table represented by the following general formula (Formula 5) such as a titanate is used. It is preferably exemplified.

[0027]

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). , A metal selected from zirconium and hafnium.).

What is important in the present invention is to completely crosslink only the portion where the catalyst has penetrated by contacting with the catalyst solution and then heating so that the catalyst does not penetrate into the interior completely and uniformly. For this purpose, the molded product is brought into contact with a solution in which a catalyst is dissolved in a solvent described later in a relatively high concentration at a relatively low temperature for a relatively short time. The contact temperature is room temperature to 150 ° C., and the contact time is several minutes to several hours. In particular, the contact temperature has a great influence on the permeation of the catalyst, so an appropriate temperature is set in order to obtain the target permeation depth of the catalyst according to the characteristics of the molded product. Specifically, when the olefin is propylene, if the contact is carried out at a temperature of less than 100 ° C., the permeation of the catalyst will be 1 mm or less in 1 hour. Since the permeation rate varies depending on the type of catalyst, the type of solvent, and the concentration, it is necessary to measure the degree of permeation of the catalyst in advance using the solvent and the catalyst to be used, and to determine the conditions for the target accordingly.

As the solvent used here, specifically, a hydrocarbon compound having 1 to 20 carbon atoms and a halogenated hydrocarbon compound can be used, in particular, a halogenated hydrocarbon compound,
Aromatic hydrocarbon compounds are preferably used. Specifically, benzene, toluene, xylene, ethylbenzene,
Dichloromethane, chloroform, dichloroethane, trichloroethane, perchloroethane etc. are exemplified and usually
It is used by dissolving it so that the catalyst concentration becomes 0.1 to 10,000 ppm.

In the present invention, the catalyst is permeated to a desired depth by contact, and then the molded product is taken out and further heated to promote crosslinking. Here, the heating temperature is preferably high unless the molded product is deformed.
For example, 80-16 when the olefin is propylene
0 ° C, especially 160-200 ° C after crosslinking has progressed to some extent
May be equal to or higher than the melting point of

By the above-mentioned treatment, the molded product can be made into a molded product having a different cross-linking density in the depth direction from the surface, but by changing the contact temperature of each part of one molded product with the catalyst solution, the molded product can be changed. It is also possible to obtain a molded product having a different crosslink density depending on the position.

[0032]

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 diethylaluminum 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 480 g of powder.

The powder obtained had 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. Melting point 156 ° C, crystallization temperature 120 ° C
Was a crystalline propylene copolymer. According to elemental analysis, it contained 1.3 wt% of vinylsilane unit.

To 300 g of the obtained copolymer, 50 g of polyphenyl silicone (polymerization degree of about 1800) synthesized by reacting phenyldichlorosilane and water was added, mixed with an extruder of 20 mmφ, and press-molded to a thickness of 2 mm. A molded product of This molded product was dissolved in a solution of triphenylphosphine complex of rhodium chloride dissolved in toluene so as to be 1 g / liter so that only one surface was in contact with the catalyst solution at 80 ° C.
Contacted for hours. Then, the molded product was taken out and heat-treated at 150 ° C. for 5 hours. The obtained molded product was cut in the thickness direction to a thickness of 0.5 mm and each part was extracted with boiling xylene for 12 hours.The proportion of insoluble matter from the part in contact with the catalyst was 99%,
It was 68%, 18% and 3%, and it was possible to have a gradient in the crosslink density. On the other hand, when the sheet was completely immersed in the catalyst solution and reacted in the same manner, the rates were 99%, 98%, 99% and 98%, and it was not possible to provide a sufficient gradient.

Example 2 Polymerization was carried out in the same manner as in Example 1 except that 1 g of allylsilane was used instead of vinylsilane to produce a propylene copolymer having an allylsilane content of 0.25 wt%. 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 article was prepared in the same manner as in Example 1 except that 100 g of this powder was used, and titanium tetrabutoxide was used as the catalyst, and the immersion time in the catalyst solution was set to 3 hours. When processed into 98%, 67%, 26
%, 4% and a gradient of crosslink density was formed.

[0039]

By carrying out the method of the present invention, it is possible to obtain a functional crosslinked polyolefin molded product having a different crosslink density depending on the location of the molded product, which is of great industrial value.

Claims (1)

[Claims] 1. A molded product comprising a copolymer of alkenylsilane and olefin and a polysilicone containing Si--H groups is contacted with a catalyst solution so that the catalyst does not uniformly penetrate into the interior, and then taken out from the catalyst solution. A method for producing a crosslinked polyolefin molded article which is heterogeneously crosslinked, characterized by comprising heat treatment by heating.