JPS585321A - Production of propylene/ethylene block copolymer - Google Patents

Abstract

PURPOSE:To obtain a copolymer with a desired melt flow without affecting impact resistance, rigidity, etc., by carrying out the reaction in either stage at a different hydrogen concentration, in block-copolymerizing propylene and ethylene in two stages at different reactant ratios. CONSTITUTION:60-95wt% of the total copolymer is produced by reacting ethylene and propylene at a weight ratio of 0/100-6/94 in the presence of hydrogen and a stereoregular polymerization catalyst (e.g., diethylaluminum chloride). Next, the titled copolymer is obtained by producing 40-5wt% of the total copolymer by reacting ethylene and propylene at a weight ratio of 15/85-95/5. In this production, when the copolymerization condition in the latter stage is the same and the hydrogen concentration in the former stage is changed, it is possible to obtain the titled block copolymer having little affected physical properties such as impact resistance, and a different melt flow index.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides impact resistant,
The present invention relates to a method for producing a propylene-nithylene/block copolymer having excellent properties such as rigidity.

Crystalline polypropylene is a general-purpose resin with excellent properties such as excellent rigidity, heat resistance, and lightweight molded products, but it has the disadvantage of being brittle at low temperatures, so it is not suitable for applications that require impact resistance at low temperatures. difficult to use. Many studies have been conducted on methods to improve this drawback, and among them, a method of block copolymerizing propylene and other olefins, especially ethylene, has been proposed as an industrially useful method. 1836, Japanese Patent Publication No. 39-15535, and a further improved method was proposed in Japanese Patent Publication No. 44-20621, Special Publication No. 49-2459.
3, etc., and the copolymers obtained by this method are very excellent.

On the other hand, with the progress of application development, there are now a wide variety of demands for resins, and in particular, the properties of resins, such as impact resistance, rigidity, etc., do not change much, and the flowability of resins when melted. In other words, various types of melt flow indexes, which are usually called melt flow indexes, are required. For such purposes,
As a result of various studies, we have developed a propylene-ethylene block copolymer that has various melt flow indices and almost constant physical properties such as impact resistance and rigidity through an extremely simple process by special molecular design. The present invention was completed by discovering a method for obtaining this combination.

An object of the present invention is to provide a method for producing propylene/-ethylene block copolymers having various melt flow indexes without substantially changing physical properties such as impact resistance and rigidity.

The present invention uses a stereoregular catalyst to produce a propylene-ethylene block copolymer with an ethylene/propylene reaction ratio of 04°. -/94 weight ratio reaction is 60 to 9 of the total polymerization amount
5 weight, and then the reaction ratio of ethylene/propylene was 1.
When producing a propylene-ethylene block copolymer by carrying out a reaction with a ratio of 85 to 5% by weight of the total polymerization amount, the reaction ratio of ethylene/propylene is 15/8s''-9% by weight Polymers with different molecular weights can be obtained and have various melt flow indices by carrying out the reaction at a constant ratio and changing the hydrogen concentration at a reaction ratio of ethylene/propylene of %oo to /94 by weight. The present invention relates to a method for obtaining a propylene-ethylene block copolymer.

The present invention can be carried out by a solvent polymerization method using an inert solvent as a medium, a bulk polymerization method using propylene itself as a medium, or a gas phase polymerization method using substantially no liquid medium.

The stereoregular catalyst used in the present invention is not particularly limited as long as it is a catalyst system used for the usual stereoregular polymerization of propylene. various carriers,
For example, a catalyst system is used in which a solid catalyst component is magnesium, aluminum, manganese, etc. supported on chloride, and an organometallic compound such as aluminum, zinc, magnesium, etc. is combined with the solid catalyst component, and furthermore, a suitable organic compound is used. For example, esters, ethers, amines, amides,
It is also possible to add phosphate esters, silicate esters, etc. as stereoregularity improvers.

Regarding the temperature and pressure of the polymerization reaction in the present invention, the appropriate range is determined depending on the above polymerization method, catalyst system, and ethylene/propylene reaction ratio, but it is usually 0°C to 1°C.
It is generally carried out at 00°C and normal pressure to 50cm2 gauge.

In the present invention, the reaction ratio of ethylene/propylene is 60 to 95% by weight of the total polymerization amount, and then the reaction ratio of ethylene/propylene is IV85 to 94% by weight of the total polymerization amount. 9515 It is an essential condition to carry out the reaction at a weight ratio of 40 to 5 weight ratios, and by carrying out the copolymerization under the above conditions, impact resistance,
A polymer with an excellent balance of rigidity and physical properties can be obtained.

Ethylene/propylene reaction ratio is 15/ss~9515
Reactions with weight ratios are multi-stage polymerizations with different reaction ratios, e.g. 15/85 to 5015 o weight ratios and 40/6 o to so
It is also possible to adopt a method in which the reaction is carried out in multiple stages, such as a reaction at a weight ratio of /20.

In the present invention, the reaction conditions 85 5 in which the reaction ratio of ethylene/propylene is 15/ to 95/by weight are fixed, and the reaction ratio of ethylene/propylene is O/ to 6.
/ weight ratio reaction at different hydrogen concentrations of 100 94 , the reaction ratio of ethylene / propylene was 0.
Propylene-ethylene propylene copolymers having a wide range of melt flow index can be obtained by changing only the molecular weight of the polymer portion with a weight ratio of /1oo to 6/94.

In order to obtain a lupropylene-ethylene block copolymer with a wide range of melt flow index, the molecular weight can be changed to obtain a copolymer with an ethylene/propylene reaction ratio of 15/~9515 by weight. In order to significantly change the melt flow index, it is necessary to significantly change the molecular weight of the polymer at the reaction ratio, and furthermore, although the reason is not clear, physical properties such as rigidity and impact resistance change significantly. .

Furthermore, when the molecular weight is varied over the entire reaction region, physical properties such as rigidity and impact resistance vary greatly even if the range of molecular weight change is not large. Furthermore, if the molecular weight is changed in the part where the above-mentioned ethylene/propylene reaction ratio obtains a copolymer with a weight ratio of 15/ss to 9515, especially if the molecular weight is changed to a low molecular weight,
Many polymers are soluble in the medium, and in the solvent method and bulk polymerization method, the yield of the product relative to the monomer used is reduced.
Moreover, the operability of the process is also greatly reduced, giving undesirable results.

In addition to the above-mentioned effects, the method of the present invention provides a very good correlation between the hydrogen concentration in the gas phase and the molecular weight of the resulting polymer in propylene homopolymerization or small ethylene-propylene copolymerization. It also has the effect that it is extremely easy to obtain a polymer with a desired molecular weight.

By carrying out the method of the present invention, a propylene-ethylene block copolymer with an excellent balance of physical properties such as rigidity and impact resistance can be obtained with a melt flow index in a wide range, and is of great industrial value. .

The method of the present invention will be explained in more detail below using Examples. In the examples and comparative examples, bending rigidity ASTM D747-63 Sharpy (with notch) ASTM D256-56
Each was measured using Dupont JIS K6718.

Using a stereoregular catalyst consisting of diethylaluminium chloride 50- and an autoclave with an internal volume of 300β, the total pressure of the propylene homopolymerization section was 5 Kg/crn2-
Gauge, polymerization temperature 60℃, total pressure in the first stage of copolymerization section 2Kg
/an2-gauge, polymerization temperature 50°C, total pressure in the second stage of copolymerization section 3 kg 7cm''-gauge, polymerization temperature 50°C.Detailed reaction conditions are shown in Table 1.Propylene After the homopolymerization was completed, the gas phase was purged and a portion of the slurry was sampled, and then hydrogen, propylene, and ethylene were charged to a predetermined concentration and a copolymerization reaction was performed. Charge 50fi methanol 6
After stirring at 0° for 30 minutes, 50 Il of water was added to remove the aqueous layer, and the heptane layer was further washed with water at 50°C twice, filtered and dried to obtain a powder, and a known stabilizer was added. In addition, after granulation, physical properties were measured.

Comparative Examples 1 to 2 A case in which a high IIO copolymer was obtained by reducing only the molecular weight of the copolymerization part (Comparative Example 1), a case in which a high MI was obtained by reducing the molecular weight of the copolymerization part and the propylene homopolymerization part ( Comparative Example 2) is shown. The powder yield was significantly reduced, and the resulting copolymer also had significantly reduced flexural rigidity.

Claims (1)

[Claims] A propylene-ethylene block copolymer is prepared using a stereoregular catalyst at a reaction ratio of ethylene/propylene. . -7
/94 weight ratio reaction was carried out in an amount of 60 to 95% by weight of the total polymerization amount, and then the ethylene/propylene reaction ratio was /85 to 15.
In the method for producing a propylene-ethylene block copolymer, the reaction ratio by weight is 40 to 5% by weight of the total polymerization amount, and the reaction ratio of ethylene/propylene is 1%.
5 to 9515 A method for producing propylene-ethylene block copolymers having various melt flow indexes, in which polymers having different molecular weights are obtained by carrying out reactions in weight ratios under constant conditions.