JP3171655B2 - Method for producing crosslinked polyolefin molded article - Google Patents

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 molded article. More specifically, the present invention relates to a method for producing a molded article comprising a specific copolymer, polysilicone, and an unsaturated compound with a catalyst by a specific method to produce a non-uniformly crosslinked polyolefin molded article.

[0002]

2. Description of the Related Art Crosslinking of a polyolefin for the purpose of improving mechanical properties, improving solvent resistance, improving heat resistance and the like is widely performed. 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. In some applications, the molded article is required to have a cross-linking density that is partially different from that of the entire molded article that is uniformly cross-linked.

[0004]

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

That is, according to the present invention, a molded product comprising a copolymer of alkenylsilane and olefin, a silicone containing Si--H groups and a compound containing at least two unsaturated bonds is prepared by treating a rhodium salt with the following general formula ( Chemical 7)

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
Selected from alkoxy compounds of Table Group IVB metal catalyst is contacted with the catalyst solution so as not uniformly penetrate into the inside, then heterogeneously crosslinked, characterized in that the heat treatment is taken out from the catalyst solution This is a method for producing a crosslinked polyolefin molded article.

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, the 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 and particularly preferably about 1.0 to 5.0.

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 silicone containing a Si—H group include compounds represented by the following general formula (Formula 3).

[0021]

Embedded image (Wherein 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 a corresponding alkyldichlorosilane or allyldichlorosilane represented by the following general formula (Formula 4) with water.

[0023]

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

The proportion of the polysilicone 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. . 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.

In the present invention, the compound containing at least two unsaturated bonds includes aromatic vinyl compounds such as divinylbenzene, diisopropenylbenzene, diallylbenzene, etc. Examples thereof include unsaturated esters such as methacrylate and ethylene glycol diacrylate, and polymers such as polybutadiene and polyisoprene. Any compound can be used as long as it has at least two reactive unsaturated bonds.

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

The method of mixing the above-mentioned alkenylsilane-olefin copolymer, polysilicone, a compound containing two unsaturated bonds, and, if necessary, the polyolefin to be mixed is not particularly limited, and the method of mixing the powder with a conventional method is not limited. It is mixed and used as it is, or further melt-kneaded and granulated. The molding is performed prior to contact with the following catalyst, and 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 molded article having a high crosslinking point concentration can be obtained.

The catalyst used in the present invention may be 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 5) such as a titanate ester.
It is .

[0029]

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.)

[0030] What is important in the present invention is to allow only the fully crosslinked portion in which the catalyst is permeated by the catalyst is contacted with followed heated with the catalyst solution so as not to completely uniformly penetrate into the inside. Therefore the is performed by a relatively short contact time at a relatively low temperature to a solution in a relatively high concentration of the catalyst molded product in a solvent described later. The contact temperature is normal temperature to 150 ° C, and the contact time is several minutes to
A few hours. In particular, since the contact temperature greatly affects the permeation of the catalyst, an appropriate temperature is set in accordance with the characteristics of the molded article so that the target permeation depth of the catalyst is obtained. Specifically, when the olefin is propylene, if the contact is carried out at a temperature lower than 100 ° C., the permeation of the catalyst becomes 1 mm or less in one hour.
Since the permeation speed 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 determine the conditions for the target accordingly.

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.

In the present invention, after the catalyst is infiltrated to a desired depth by contact, the molded product is taken out and further heated to promote crosslinking. Here, the heating temperature is desirably high as long as the molded product is not deformed.
For example, if the olefin is propylene,
60 ° C, especially 160-200 ° C after crosslinking has progressed to some extent
Or higher.

By the above-described treatment, the molded product can be formed into a molded product having different crosslink densities in the depth direction from the surface. However, by changing the contact temperature of each part of one molded product with the catalyst solution, the molded product can be obtained. A molded article having a different crosslink density depending on the position may be used.

[0034]

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%.

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 in a 5-liter autoclave, 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 as 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, and the melting point was 156 ° C. and the crystallization temperature was 120 ° C.
Is a crystalline propylene copolymer. According to elemental analysis, it contained 1.3 wt% of a vinylsilane unit.

To 300 g of the obtained copolymer, 30 g of polyphenylsilicone (degree of polymerization: about 1800) synthesized by reacting phenyldichlorosilane and water and 10 g of divinylbenzene were added, mixed with an extruder having a diameter of 20 mm, and press-formed. And thickness 2
mm was obtained. This molded product was contacted with a solution of rhodium chloride triphenylphosphine complex dissolved in toluene at 1 g / liter at 80 ° C. for 2 hours so that only one surface was in contact with the catalyst solution. Next, the molded product was taken out and heated 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. %, Indicating that the crosslink density could have a gradient. On the other hand, when the sheet was completely immersed in the catalyst solution and reacted similarly, 99%, 98%,
It was 98% and 98%, and could not have a gradient.

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. The η of the copolymer was 1.85, the melting point was 158 ° C., the crystallization temperature was 115 ° C., and the ratio of extraction residues when extracted with boiling n-heptane for 6 hours was 96.8%.

Example 1 was repeated except that 100 g of this powder was used, and diisopropylbenzene was used instead of divinylbenzene.
A molded article was prepared in the same manner as in Example 1, except that titanium tetrabutoxide was used as the catalyst and the immersion time in the catalyst solution was set to 3 hours, except that 98%, 61%,
A gradient of crosslink density was formed at 34%, 4%.

[0041]

By carrying out the method of the present invention, a functional crosslinked polyolefin molded article having a different crosslink density depending on the location of the molded article can be obtained, which is extremely valuable industrially.

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) C08J 3/00-3/28 C08J ⁷ /00-7/18 C08L 1/00-101/16

Claims (1)

(57) [Claims] 1. A molded article comprising a copolymer of alkenylsilane and olefin, a silicone containing Si--H groups and a compound containing at least two unsaturated bonds.
Rhodium salts and 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
Selected from alkoxy compounds of Table Group IVB metal catalyst is contacted with the catalyst solution so as not uniformly penetrate into the inside, then heterogeneously crosslinked, characterized in that the heat treatment is taken out from the catalyst solution A method for producing a crosslinked polyolefin molded article.