JPS62132912A - Production of block copolymer of propylene - Google Patents

Abstract

PURPOSE:To obtain the titled copolymer having improved balance of rigidity and impact resistance by the use of a smaller amount of ethylene, by subjecting propylene bulk polymerization at first and carrying out copolymerization of propylene/ethylene in a specific reaction ratio in the presence of an organolithium compound. CONSTITUTION:Firstly propylene alone or together with a small amount (preferably <=6wt%) of another alpha-olefin are polymerized preferably at 50-90 deg.C usually in the presence of a catalyst (e.g., titanium trichloride obtained by reducing titanium tetrachloride with metallic aluminum, hydrogen or organoaluminum compound) in a polymerization amount of preferably 50-95wt%. Then ethylene is fed to the reaction system and propylene is copolymerized with ethylene in the presence of an organolithium compound (e.g., methyllithium, etc.,) in a weight ratio (based on the catalyst) or usually 0.5-100 usually at 30-60 deg.C in such a way that a reaction ratio of propylene/ethylene becomes 80/20-5/95 (weight ratio) to give the aimed copolymer.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to a method for producing a block copolymer of propylene. Specifically, the present invention relates to a method for producing a block copolymer of propylene by a bulk polymerization method using propylene itself as a liquid medium.

[Conventional technology]

Copolymerization of propylene with other α-olefins, especially ethylene, has been used to improve the impact resistance of polypropylene (especially at low temperatures), and also to simplify the process or reduce the amount of soluble polymer in the liquid medium. Since propylene itself can be used as a liquid medium, a bulk polymerization method is also used. By the way, in order to produce a block copolymer using the bulk polymerization method, it is necessary to increase the amount of ethylene used and raise the overall pressure in order to reduce the propylene/ethylene reaction ratio. There is a problem that it is difficult to carry out continuous polymerization by reducing the reaction ratio of /ethylene, and to solve this problem, methods of combining continuous polymerization and batch polymerization have been attempted (for example, 5
7-30534, JP-A-57-145114, JP-A-5
7-145115, JP-A-57-149319, JP-A-57-149320, etc.).

[Problem that the invention seeks to solve]

However, although the above-mentioned method of combining continuous polymerization and batch polymerization allows reactions with relatively small propylene/ethylene reaction ratios to be carried out to some extent, it is necessary to increase the ethylene partial pressure, and a large amount of There were problems such as the need to recover ethylene.

[Means to solve the problem]

The inventor of the present invention has conducted extensive studies on methods for solving the above problems, and has completed the present invention.

That is, in the present invention, propylene itself is used as a liquid medium, and propylene is first polymerized alone or propylene and a small amount of other α-olefin are copolymerized, and then the reaction ratio of propylene/ethylene is 80/20 to 5.
/95 (weight ratio) to produce a propylene block copolymer, the propylene/ethylene reaction ratio is 80/2 to 5/95 (weight ratio). This is a method for producing a block copolymer of propylene, characterized in that it is carried out in the presence of a propylene block copolymer.

In the present invention, various known catalyst systems that provide polypropylene with high stereoregularity can be used as catalysts for polymerizing propylene, and there are no particular limitations. For example, as a solid catalyst, titanium tetrachloride can be used as a metal aluminum, hydrogen,
Titanium trichloride obtained by reduction with organoaluminum or those modified with an electron-donating compound; furthermore, supports such as magnesium halide or those treated with an electron-donating compound are modified with a titanium halide. Examples include things.

The above-mentioned solid catalyst is used in the polymerization of propylene in combination with an organoaluminum compound and, if necessary, an electron-donating compound.

Examples of organoaluminum compounds include trialkylaluminum, dialkylaluminum halide, alkylaluminium sesquihalide, alkyl aluminum civalide, etc., and the alkyl residue includes a methyl group,
Examples include ethyl group, propyl group, butyl group, and hexyl group. Further, examples of the no-ride include chlorine, bromine, and iodine.

If necessary, esters, ethers, orthoesters, alkoxy silicones, and the like are used in combination as stereoregularity improvers.

Here, the usage ratio of organoaluminium and stereoregularity improver to the solid catalyst is usually 0.5 to 10, respectively.
0.0.01-30 is suitable.

In the present invention, propylene itself is used as the polymerization medium, but up to about 20 wt% hexane, heflin,
Other futile media such as benzene and toluene may also be used in combination, and this is also included.

In the present invention, the initial copolymerization of propylene alone or of propylene and a small amount of other α-olefins is carried out using only the above catalyst system. The amount of polymerization under this condition is 5 of the total amount of polymerization.
The content is preferably 0 to 95% by weight, and if it is less than 50% by weight, the original rigidity of polypropylene is lost, which is not preferable. Also, if the amount is more than 95% by weight, the impact-resistant edge will not be improved enough.

The α-olefin to be copolymerized with propylene is ethylene, butene-1, hexene-1,2-methylpentene-1, etc., and the amount of copolymerization is preferably 6% by weight or less, and 6% by weight. If it exceeds this, the rigidity of the copolymer will decrease, which is not preferable.

The polymerization during this period is preferably carried out at a polymerization temperature of 50 to 90°C, and the polymerization pressure at that time is determined by the inert solvent used, the amount of hydrogen for adjusting the molecular weight, the polymerization temperature, etc.

In the present invention, copolymerization is then carried out so that the reaction ratio of propylene/ethylene is 80/20 to 5/95 by weight. What is important here is that organolithium be present in the system during this reaction.

Examples of the organolithium used here include alkyllithium, aryllithium, and phenyllithium, with alkyllithiums such as methyl+1thium, ethyllithium, and butyllithium being particularly preferred.

There is no particular restriction on the amount of organic lithium used, but it is generally used in a weight ratio of 0.5 to 100 with respect to the solid catalyst, and the above-mentioned organic aluminum can also be used in combination. The propylene/ethylene copolymerization reaction is usually 30
It is generally carried out at a temperature of 60° C. to 60° C., and the pressure is determined by the desired concentration of ethylene and hydrogen in the gas phase.

In the present invention, the reaction ratio of propylene/ethylene is 80
If it is larger than /20, the effect of improving impact resistance is insufficient, and if it is smaller than 5/'95, the effect of improving impact resistance is insufficient.

Propylene/ethylene reaction specific force 80/20 to 5/95
It is preferable that the copolymerized portion is 50 to 5% by weight based on the total polymerization. If it exceeds 50% by weight, the rigidity tends to be poor, and if it is less than 5% by weight, the impact resistance will deteriorate. It may become defective.

〔Example〕

Hereinafter, the present invention will be further explained with reference to Examples.

Reference Example 1 1) Preparation of solid catalyst component In a pulverizing pot with an internal volume of 41 and containing 9 kg of steel balls with a diameter of 12 mm, 300 g of magnesium chloride, 60 g of tetraethoxysilane, and α,α,α-trichlorotoluene were added in a nitrogen atmosphere. 45- was added and shaken for 40 hours to pulverize.

300 g of the above co-pulverized material was placed in a No. 51 flask, 1.51 g of titanium tetrachloride and 1.51 g of toluene were added, stirred at 100°C for 30 minutes, allowed to stand, and the supernatant liquid removed twice. , and then washing the solid content with 41 n-hebutane was repeated 10 times. A portion of the obtained solid catalyst slurry was sampled and the titanium content was analyzed and found to be 1.9 wt%.

ii) In a polymerization reaction autoclave with an internal volume of 51 cm, 20 cm of the above solid catalyst and 0.12 cm of diethylaluminium chloride were added under a nitrogen atmosphere.
8d, p-) Add 0.06i of methyl ruylate and 0.03i of triethylaluminum, then add 1 of propylene.
．． Charge 8 kg, add 3.3Nl of hydrogen, and
The polymerization reaction was carried out at 5°C for 2 hours, after which unreacted propylene was purged, and the polymer was taken out and weighed dry. The intrinsic viscosity of the obtained polymer in a tetralin solution at 135° C. and the proportion of the extraction residue extracted with boiling n-hebutane for 6 hours (hereinafter abbreviated as η and II, respectively) were measured.

The results are shown in Table-1.

Reference Example 2 After carrying out the polymerization reaction at 75°C for 2 hours, the temperature of the autoclave was further lowered to 40°C, and Reference Example 1 was repeated except that stirring was continued at 40°C for 1 hour to obtain a polymer. The η and II of the obtained polymer were measured.

Reference example 3 After cooling down to 40°C, ethylene partial pressure is 10kg/crd
Reference Example 2 was repeated except that ethylene was charged so that -G was obtained, and a polymer was obtained. The η and II of the obtained polymer were measured. The results are shown in Table-1.

As seen in the results of Reference Example 2.3, the reaction at 40° C. after polymerization at 75° C. for 2 hours was hardly entrained, regardless of the presence or absence of ethylene.

Examples 1 to 4 and Comparative Examples 1 to 3 In Reference Example 2, after the temperature was lowered to 40°C, ethylene was charged so that the ethylene partial pressure was as shown in the table, and η, 11 and melt flow index of the rock copolymer were (MI)
was measured. In addition, the total weight W of the copolymerization portion of ethylene and propylene was determined by the column fractionation method (Chubu Chemical Association Branch Federation Autumn Conference 13th Lecture Proceedings 3A20 (1982)) to determine the reaction ratio in the copolymerization portion. , and the ethylene content W2 of the part was calculated as (W+-W2)/W2.

These results are shown in Table-1.

A known stabilizer is added to the obtained block polymer and granulated, and an injection sheet with a thickness of 1 mm is made.
The following physical property values were measured. The results are shown in Table-2.

Bending stiffness ASTM D-747-63 (20
°C) DuPont impact strength JIS K-6718 (2
(0°C, -10°C) By adding organolithium, polymerization progressed at a relatively high ethylene reaction ratio even at low ethylene partial pressure (Table -
1), and when the same reaction ratio and the same copolymerization portion are used, the balance between rigidity and impact resistance is better than that obtained by polymerizing only organic aluminum (Table C-2).

〔Effect of the invention〕

By carrying out the method of the present invention, a propylene block copolymer can be efficiently produced and is of great industrial value. In other words, it is possible to produce a propylene-ethylene copolymer with a small propylene/ethylene reaction ratio even at a relatively low ethylene partial pressure, and in other words, it is possible to produce a propylene-ethylene copolymer with a small propylene/ethylene reaction ratio. It is possible to obtain a copolymerized portion with a desired propylene/ethylene reaction ratio, and it is extremely valuable industrially.

Claims (1)

[Claims] 1. Using propylene itself as a liquid medium, first polymerize propylene alone or copolymerize propylene with a small amount of other α-olefin, and then adjust the reaction ratio of propylene/ethylene to 80/20 to 5/95 (weight ratio). ) to produce a block copolymer of propylene,
Propylene/ethylene reaction ratio is 80/20 to 5/95
(weight ratio) in the presence of an organolithium.