JPS60217112A - Manufacture of propylene/ethylene random copolymer for film - Google Patents

Abstract

PURPOSE:To manufacture propylene/ethylene random copolymer for a film having good transparency by copolymerizing propylene and ethylene with steroscopic regular catalyst. CONSTITUTION:A propylene/ethylene random copolymer which contains 0.1- 8wt% of ethylene content is manufactured with catalyst which has active titanium catalyst obtained by carrying magnesium chloride and catalyst having organic aluminum by a lump polymerization. Then, the copolymer is granulated by a granulating machine which has a continuous kneader and a gear pump. The copolymer obtained in this manner is molded in an inflation film by an extruder having 40mm.. The film has high transparency and preferable openability.

Description

DETAILED DESCRIPTION OF THE INVENTION Object of the Invention The present invention relates to a method for producing a propylene/ethylene random copolymer having good transparency. Specifically, the present invention relates to a method for obtaining a propylene/ethylene random copolymer with good transparency using a specific granulator.

For the purpose of improving the impact resistance of polypropylene and lowering the heat sealing temperature, it is well known that a method of random copolymerization of a small amount of ethylene and, in some cases, an even smaller amount of an α-olefin having 4 to 6 carbon atoms, is used. The product is available on the market. If the transparency of these substances is improved, there is a problem that the film becomes sticky and the so-called blocking properties and opening properties become poor.Therefore, methods such as improving the catalyst or adding additives to it are being carried out, but the above transparency cannot be improved. It is still difficult to say that the balance between opening and opening is sufficient.

The inventors of the present invention have conducted intensive studies on methods to solve the above problem. As a result, by granulating propylene/ethylene random copolymer powder using a granulator with a specific mechanism, the above balance between transparency and openness can be achieved. The present invention was completed based on the discovery that the present invention can be improved.

The purpose of the present invention is to produce a napropylene/ethylene random copolymer with a good balance between transparency and openness.Propylene/ethylene random copolymer powder with an ethylene content of 0.1 to 8 wt% obtained by copolymerizing ethylene. The present invention relates to a method for producing a napropyrene/ethylene random copolymer with good transparency, which comprises granulating it using a granulator comprising a continuous kneading section and a gear pump.

In the present invention, it is possible to use a known random copolymer powder as the propylene/ethylene random copolymer powder, and there are no particular restrictions on the number, but the one suitable for film use is one with an intrinsic viscosity of 1 as measured in a tetralin solution at 135°C. It is about .3 to 2.0. If the ethylene content is less than 0.1 wt%, the transparency is poor;
% or more, the inherent rigidity of polypropylene is lost, which is not preferable. Furthermore, in order to improve transparency and heat sealability, a small amount of α-olefin having 4 to 6 carbon atoms (content of 0.1 to
5 wt%) may also be present.

Various known catalysts can be used as stereoregular catalysts, such as an active titanium trichloride catalyst and an organoaluminum catalyst, or an active titanium catalyst obtained by supporting titanium tetrachloride or titanium trichloride on magnesium trichloride. Any catalyst system, such as a catalyst consisting of a Hebutane extraction residual rate (hereinafter abbreviated as II)
It is preferable to use a highly stereoregular catalyst having a width of 90 or more. In a catalyst system that can only obtain a lower value of II,
Even if a random copolymer is granulated, it is difficult to obtain a propylene/ethylene random copolymer with good transparency and openness.

There are no particular limitations on the random copolymerization method of fluoropylene/ethylene, and examples include a solvent polymerization method using an inert liquid medium as a polymerization medium, a bulk polymerization method using propylene itself as a liquid medium, or a gas polymerization method using substantially no liquid medium. It is possible to produce the propylene/ethylene random copolymer by a phase polymerization method, etc., and the ethylene content in the resulting propylene/ethylene random copolymer is 0.
The ratio of ethylene to propylene in the polymerization system may be controlled so that the amount is 1 to 8 wt%.

Propylene/propylene that is highly effective by applying the method of the present invention
Although the reason is not clear, ethylene random copolymer powder is obtained by a liquid bulk polymerization method using propylene itself as a medium or a gas phase polymerization method, and in particular, magnesium chloride and titanium tetrachloride are used as catalysts. It was obtained by using an activated titanium catalyst obtained by supporting a titanium catalyst and an organic aluminum.

What is important in the present invention is that even if the same propylene/ethylene random copolymer powder is used, the balance between transparency and openness of the propylene/ethylene random copolymer obtained differs greatly depending on the mechanism of the granulator. That's true.

What is important in the present invention is to granulate the propylene/ethylene random copolymer powder using a granulator comprising a continuous cross section and a gear pump. That is, the object of the present invention cannot be achieved by using an extruder, which is an ordinary granulator, or by combining a continuous cross-wire section and an extruder.

In the present invention, the propylene/ethylene random copolymer powder is mixed with an antioxidant, an ultraviolet absorber, etc., and if necessary, a nucleating agent, etc., and then fed into the mixed line part of the granulator using an appropriate feeder. are introduced and melted and mixed in the cross section.

It is more preferable to use a structure in which a two-axis screwdriver is provided in the cylinder as the mixing section, since intimate mixing can be achieved with a relatively small mixing section.

The appropriate temperature of the cross section is not specified, depending on the molecular weight or ethylene content of the copolymer, but is usually 150°C to 28°C.
It is 0°C. The residence time of the propylene/ethylene random copolymer in the crosstalk section cannot be specified since the appropriate range varies depending on the temperature of the core section, etc., but it is usually 15 to 30 seconds.

In the present invention, the resin kneaded in the continuous mixing section is then taken out by a gear pump.

Many types of gear pumps are commercially available for transferring heat-resistant, high-viscosity polymer melts, and can be used as they are. It may be determined as appropriate depending on the molecular weight of the propylene/ethylene random copolymer, ethylene content, etc. so that the temperature of the core and the load of the gear pump are within an appropriate range.

In a preferred embodiment of the present invention to be carried out on an industrial scale, a die of an appropriate shape is installed on the discharge side of a gear pump, and the propylene/ethylene random copolymer coming out of the die is cut into a suitable size with a strand cutter or an underwater cutter. The process is to cut it into pieces of appropriate size and make it into pellets. A suitable combination is, for example, Japan Steel Works Co., Ltd. CMP.
-90 Since polyα-olefins are relatively easily decomposed by oxygen in the air or ultraviolet rays, and their physical properties as polymers deteriorate, they need to be mixed with antioxidants, ultraviolet absorbers, etc. before being marketed. . For this reason, the granulation process is usually an essential step in bringing polypropylene to the market, and in the conventional granulation process using an extruder, it is necessary to decide whether to emphasize transparency or openness depending on market needs. However, it was necessary to carry out strict control and to ship the obtained propylene/ethylene random copolymer separately according to the intended use. However, by carrying out the method of the present invention, products with good transparency and openability can be easily obtained, which has great industrial value. EXAMPLES The present invention will be explained in further detail with reference to Examples below.

Examples and Comparative Examples 1) Production of propylene/ethylene random copolymer howder 1) Copolymerization of ethylene and propylene using an activated titanium catalyst obtained by supporting on magnesium chloride and a catalyst consisting of organoaluminium by bulk polymerization method. The following three types of propylene/ethylene random copolymers were produced by adjusting the hydrogen concentration and ethylene concentration in the gas phase by the method of obtaining an ethylene/propylene random copolymer.

Sample A) Ethylene content 4.6% 1' Intrinsic viscosity number (hereinafter abbreviated as η) measured in tetralin solution at 35°C 1
．． 65 Sample B) Ethylene content 2.8% η 1.58 Sample C) Ethylene content 3.2% η 1.62 I) N-hebutane 1000/h was charged into an autoclave with an internal volume of 30007, and then Marubeni Solve Co., Ltd. was charged as a catalyst. Highly active titanium TBN-05 (loft number) 10 (l diethyl aluminum chloride 800- was added to total pressure 6 to 9/d-gauge gas phase ethylene concentration 2.2 vo 1% gas phase hydrogen concentration 8.5 vo /% at 6θ℃ for 2 hours, then methanol 2001 was added and treated at 70℃ for 30 minutes, water 2001 was added and treated at 50℃, the hebutane layer was filtered, and Citepropylene/ethylene random copolymer powder (ethylene content 4 (Sample K) 2) Granulation of propylene/ethylene random copolymer A phenolic antioxidant (0.2 wt% intrinsic viscosity 1.62) was obtained.
t%), calcium stearate (0.1 wt%), and lubricant (0.2 wt%), and extruder D was used as a granulator.
(Manufactured by Japan Steel Works, Ltd., 90 mm diameter single screw extruder, Comparative Examples 1 to 3), E (made by Japan Steel Works, Ltd., consisting of a continuous cross-wire section and an extruder)
Pelletization was carried out under the conditions shown in the table using Comparative Examples 4 to 6 (trade name: Comparative Examples 4 to 6) and F (Comparative Examples 1 to 6) consisting of a continuous cross-wire section and a gear pump.

3) Production of film and evaluation of film physical properties Using the propylene/ethylene random copolymer obtained in 2), a blown film (folding diameter 19cm) was produced using a 40-inch extruder.
A film (thickness: 0.03 cm) was molded and the physical properties of the film were measured.

For the copolymers of Examples, the conditions were changed to examine the balance between transparency and opening requirements. Good opening properties even under conditions of high transparency.

The evaluation of the film was conducted as follows.

Measured at 230℃ according to MFI JIS K7210 (g
/10m1n) Haze According to JIS K6714 (%) Openness
Mitsui Toatsu Chemical Co., Ltd. Method A, A', B1BtC%C'
, D, and D', with A being the best and D' being the worst Tensile test Young's modulus Tensile strength according to ASTM D882-64T Impact according to ASTM D8g2-64T The lowest energy that can break when a film steel ball of 10CIIXIOQI is dropped. evaluation.

Claims (1)

[Claims] 1) A propylene/ethylene runroom copolymer powder with an ethylene content of 0.1 to 8 wt% obtained by copolymerizing propylene and ethylene using a stereoregular catalyst is used in a continuous cross-wire section and a gear pump. A method for producing a propylene/ethylene random copolymer for films with good transparency, characterized by granulating it using a granulator comprising: 2) The method according to claim 1, which uses a granulator in which the continuous cross-wire section is constituted by a twin-screw.