JPH04318030A - Production of crosslinked polyolefin - Google Patents

Abstract

PURPOSE:To obtain the subject polyolefin having a crosslinked syndiotactic structure and excellent in physical properties by treating a copolymer of an alkenylsilane and an olefin having the syndiotactic structure with a compound of a group IVB metal, etc., of the periodic table. CONSTITUTION:A copolymer of an alkenylsilane and an olefin such as ethylene, having a substantial syndiotactic structure and expressed by the formula [(n) is >=1; (m) is 1-3: R is 1-5C alkyl] (used in an amount of preferably 0.1-10mol%) is treated with a compound of a group IVB or VIII metal such as titanium to afford the objective polyolefin. The intrinsic viscosity of the aforementioned copolymer is preferably 0.1-3.0.

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 crosslinked polyolefins. Specifically, the present invention relates to a method for producing a crosslinked polyolefin, which is characterized by treating a copolymer of alkenylsilane and olefin with a specific structure with a specific compound.

0002

BACKGROUND OF THE INVENTION Crosslinking reactions have been carried out for the purpose of improving the physical properties of polyolefins. However, in poly-α-olefins such as polypropylene, depolymerization of the main chain takes priority over cross-linking reactions, so simply generating radicals by decomposing peroxide or irradiating with radiation will not cause the cross-linking reaction. Rather, the decomposition progresses and the molecular weight decreases. For this reason, it is common practice to graft a monomer, such as alkoxyvinylsilane, which causes a crosslinking reaction upon hydrolysis, to a polyolefin, and then crosslink it (for example, JP-A-58-117244). On the other hand, polypropylene was the only known polyolefin with a syndiotactic structure, but recently it has been reported that syndiotactic polypropylene with extremely high regularity can be obtained using various homogeneous catalysts. (J. Am. Chem. Soc., 1
988, 110, 6255-6256)

0003

[Problems to be Solved by the Invention] Conventionally, crosslinked polyolefins having a syndiotactic structure have not been known, and if such a product can be obtained, it is expected that it will have functions that have not been seen in the past.

0004

[Means for Solving the Problems] The present inventors have earnestly searched for a method for producing a crosslinked polyolefin by solving the above problems, and have completed the present invention.

That is, the present invention is a method for producing a crosslinked polyolefin, which is characterized in that a copolymer of alkenylsilane and olefin having a substantially syndiotactic structure is treated with a compound of a metal of group IVB or group VIIIB of the periodic table. be.

In the present invention, the catalyst system used for producing the copolymer of alkenylsilane and olefin is such that when homopolymerization of propylene is carried out, the resulting polymer has a highly syndiotactic structure, and moreover, Examples include those that have good copolymerizability with silane.

[0007] A specific example is the catalyst used to produce highly syndiotactic polypropylene as shown in the above literature, but catalysts with different structures can also be used to homopolymerize propylene. Any type of polypropylene that can be used to produce polypropylene with a syndiotactic pentad fraction of 0.7 or more can be used. A catalyst consisting of a transition metal compound having as a ligand can be used.

Examples of transition metal compounds having an asymmetrical ligand include isopropyl (cyclopentadienyl-1-fluorenyl) hafnium dichloride, or isopropyl (cyclopentadienyl-1-fluorenyl) described in the above-mentioned literature.
1-fluorenyl) In addition to zirconium dichloride, compounds as shown in the following general formula (Chemical formula 2),

[0009]

[Formula 2] (where A and B are different aromatic hydrocarbons, R is a hydrocarbon residue having 1 to 20 carbon atoms connecting A and B, or a compound containing silicon, and X is a halogen atom or a carbon number 1 to 20 hydrocarbon residues (M is a metal atom selected from titanium, zirconium, and hafnium) can be preferably used.

[0010] A and B are monocyclic rings having 5 to 30 carbon atoms;
Alternatively, polycyclic aromatic compounds can be exemplified; specifically, cyclopetadiene or cyclopetadiene, or those in which part or all of the hydrogens are substituted with an alkyl group having 1 to 10 carbon atoms (herein, the alkyl group has its terminal end again cyclopentadiene). ), polycyclic aromatic compounds such as indene and fluorene, or those in which some or all of the hydrogen atoms are substituted with an alkyl group having 1 to 10 carbon atoms are exemplified. .

[0011] R is preferably a dialkylmethylene group or a dialkylsilylene group, such as R'2C,
R'2Si (wherein R' is hydrogen or has 1 to 20 carbon atoms)
The alkyl residues may be the same or different, and two R' may be bonded to each other. ) Compounds represented by these formulas can be preferably used, and ethylene groups represented by -CR'-CR'- can also be exemplified (in the formula, R' is the same as above).

Examples of X include fluorine, chlorine, bromine, iodine, alkyl groups such as methyl, ethyl, propyl and butyl, and aromatic compounds such as cyclopentadienyl groups, with chlorine and methyl groups being particularly preferred.

[0013] As the aluminoxane, compounds represented by the following general formula (Formula 4) or (Formula 5),

001
4]

[C3]

[0015]

[Formula 4] (wherein R is a hydrocarbon residue having 1 to 3 carbon atoms, n is 1
An integer greater than or equal to ) can be exemplified, particularly in methylaluminoxane where R is a methyl group, n is 5 or more, preferably 10
The above are used.

The ratio of aluminoxane to the above-mentioned transition metal compound is 10 to 1,000,000 times by mole, usually 50 to 5,000 times by mole. Furthermore, it is also possible to use a catalyst system obtained by treating the transition metal compound in advance with trialkylaluminum and then contacting it with a compound that reacts and forms ion pairs.

In the present invention, the alkenylsilane may be any alkenylsilane as long as it contains an Si--H group, and those represented by the following general formula (Formula 5) can be preferably used.

[0018]

[Chemical formula 5] H2C=CH-(CH2)n-SiHm R3
-m (in the formula, n is an integer of 1 or more, m is an integer of 1 to 3,
R is an alkyl residue having 1 to 5 carbon atoms. ) Vinyl silanes have a problem of poor activity for unknown reasons, and those with m of 3 also have poor activity during polymerization compared to those with m of 1 to 2. There is a problem that alkenylsilane units are difficult to introduce.

In addition, as the olefin, the following general formula (Chemical formula 6) is used.
),

[0020]

[Chemical formula 6] H2C=CH-R (in the formula, R is a hydrocarbon residue having 1 to 12 carbon atoms), 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 its derivatives are also exemplified.

[0021] There are no particular restrictions on the polymerization conditions, and solvent polymerization using an inert medium, bulk polymerization in which an inert medium is not substantially present, and gas phase polymerization can also be used.

[0022] Polymerization temperature is -100 to 200°C
The polymerization pressure is generally from normal pressure to 100 kg/cm2. Preferably -100 to 100
℃ and normal pressure to 50 kg/cm2.

The preferred molecular weight is 0.1 to 3.0 as the intrinsic viscosity measured in a tetralin solution at 135°C.
Generally, it is about a certain degree.

What is important in the present invention is that the copolymer has the desired stereoregularity and that the two or three consecutive propylene parts in the polymer chain are racemic in nature. , for example, in a propylene copolymer, 1 in trichlorobenzene according to 13C-NMR.
When measured at 35°C, based on tetramethylsilane,
The peak of the methyl group attributed to the syndiotactic structure of propylene appearing at about 20.2 ppm is 0.5 or more, more preferably 0.7 or more relative to the sum of all the methyl group peaks.

There is no particular restriction on the polymerization ratio of alkenylsilane and olefin, but when used in combination with polyolefin, alkenylsilane usually has a polymerization ratio of 0.
About 0.001 to 30 mol%, preferably 0.1 to 10
It is mole%. Also, when used alone, 0.000
It is about 1 to 1 mol%.

The molecular weight of the copolymer is not particularly limited, but when it is intended to improve the physical properties by mixing it, it is preferably about the same molecular weight as the polyolefin or less. In some cases, polymerization similar to polyolefin (composition, molecular weight, etc.) except that it contains alkenylsilane
For example, block copolymerization may be performed and alkenylsilane may be copolymerized only in the first stage or only in the second stage.

In the present invention, the above-mentioned copolymer is used as it is, or after being mixed with a polyolefin obtained by polymerizing the above-mentioned olefin without copolymerizing it with alkenylsilane, it is mixed with a compound of a metal of group IVB or group VIIIB of the periodic table. It is crosslinked by treatment.

As polyolefins, it is particularly effective to apply the method of the present invention to homopolymers of α-olefins such as propylene, which are difficult to crosslink when used alone, or copolymers thereof. Methods for producing these polyolefins are already known, and various brands are available on the market. Further, a polyolefin having a syndiotactic structure can also be produced by carrying out the same method as the above-mentioned method for producing a copolymer of olefin and alkenylsilane except that alkenylsilane is not used.

[0029] In the present invention, examples of compounds of metals of group IVB or group VIIIB of the periodic table include metals such as titanium, zirconium, hafnium, rhodium, platinum, and palladium, and compounds thereof, with titanium esters and rhodium being particularly preferred. Examples include chlorides of There are no particular restrictions on the contact method, but it is common to directly mix the copolymer and the above compound, or to dissolve the compound in a solvent and mix the copolymer in the solution. 0.0 per 100 copolymer
Generally, the weight ratio is about 001 to 1.0,
Preferably, the weight ratio is about 0.001 to 0.1. Although room temperature is sufficient as the contact treatment temperature, a relatively high temperature is preferable because the reaction rate is high. Normal temperature ~30
It is 0℃.

[0030]

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

Example 1 Isopropylcyclopentadienyl-1-fluorene synthesized according to a conventional method was lithiated, reacted with zirconium tetrachloride, and recrystallized to obtain isopropyl (
cyclopentadienyl-1-fluorenyl) 10 mg of zirconium dichloride and 2 g of methylaluminoxane (degree of polymerization 16.1) manufactured by Toso Akzo Co., Ltd. were mixed into an inner volume of 200
ml autoclave, 50 g of propylene,
3.5 g of allyldimethylsilane was added and polymerized at 30° C. for 4 hours. After the reaction, unreacted propylene was purged and filtered and washed to obtain 23.9 g of polypropylene.

This polypropylene has a 13C-NMR measurement of about 20% in 1,2,4-trichlorobenzene solution at 135°C with reference to tetramethylsilane.
The peak observed at 2 ppm was 0.85 of the total peak intensity attributed to all methyl groups of propylene, indicating a syndiotactic structure. The content of allyldimethylsilane in the copolymer calculated by silicon analysis is 2.
7 mol%, and the intrinsic viscosity (hereinafter abbreviated as η) measured in a tetralin solution at 135 °C is 0.61, 1, 2,
The ratio of the weight average molecular weight to the number average molecular weight (hereinafter abbreviated as MW/MN) measured with 4-trichlorobenzene is 2.
It was 1.

This polypropylene was dispersed in a toluene solution containing 1 g/liter of t-butyl titanate and heated at 80°C.
Contact treatment was carried out for 1 hour. After the reaction, the copolymer was collected by filtration and extracted with boiling xylene for 6 hours, and the insoluble matter was 9.
1 wt%, and crosslinking was progressing. Note that the boiling xylene insoluble content of the sample treated in toluene not containing t-butyl titanate was 2.1 wt%.

Example 2 The same procedure as Example 1 was carried out except that tristriphenylphosphine rhodium chloride was used instead of t-butyl titanate, and the content insoluble in boiling xylene was 92.5 wt%.
Met.

Example 3 The same procedure as in Example 1 was carried out except that allylmethylsilane was used instead of allyldimethylsilane, and the allylmethylsilane content was 1.8 mol%, η was 0.58, and about 20.2 ppm.
12.5 g of a copolymer having a syndiotactic structure was obtained, in which the peak observed in is 0.79 of the sum of the peak intensities attributed to all the methyl groups of propylene. This polymer
When treated in the same manner as in Example 1, the boiling xylene insoluble content was 88.4 wt%.

[0036]

[Effects of the Invention] By the method of the present invention, a crosslinked polyolefin having a syndiotactic structure can be obtained, which is extremely valuable industrially.

Claims (2)

[Claims] Claim 1: A copolymer of an alkenylsilane and an olefin having a substantially syndiotactic structure according to the periodic table IVB.
1. A method for producing a crosslinked polyolefin, characterized in that it is treated with a compound of a group metal or a group VIIIB metal. [Claim 2] The production method according to Claim 1, wherein the alkenylsilane is represented by the general formula (Chemical formula 1) [Chemical formula 1] H2C=CH-(CH2)n-SiHm R3
-m (in the formula, n is an integer of 1 or more, m is an integer of 1 to 3,
R is an alkyl residue having 1 to 5 carbon atoms. )