JPS5879005A - Purification of atactic polypropylene - Google Patents

Abstract

PURPOSE:To prepare refined atactic polypropylene, by contacting atactic polypropylene with ammonia water under molten condition, thereby extremely easily removing the residue of the catalyst. CONSTITUTION:An atactic polypropylene (having an intrinsic viscosity number of 0.05-5,0, usually 0.1-3.0 measured in tetraline solution at 135 deg.C and optionally containing a comonomer such as ethylene) containing the residue of catalyst (in an amount of usually 30-20,000ppm, and usually 30-20,000ppm of halogen, preferably >=50ppm of chlorine) is mixed with ammonia water (preferably >=1mol of NH4OH per 1g-atom of the chlorine in the atactic polypropylene to be treated), and the mixture is subjected to the contact treatment usually at 80-200 deg.C for about 10min-10hr, if necessary in the presence of a surface active agent. After cooling, the ammonia water layer is separated by filtration or under molten conditions to obtain the purified atactic polypropylene.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for removing catalyst residues from crude atactic polypropylene containing relatively large amounts of catalyst residues.

So-called atactic polypropylene, which is produced as a by-product during the production of stereoregular polypropylene or copolymers of propylene with other α-olefins, impairs the physical properties of stereoregular polypropylene or copolymers of propylene with other α-olefins. It is removed from the polypropylene product.

As a method for removing the machinable atactic polypropylene, for example, a solvent polymerization method using a polymerization medium yields the stereoregular polymer as an insoluble portion in the polymerization medium and the machinable atactic polypropylene as a soluble portion.

After the polymerization reaction, the catalyst residue is often solubilized with alcohol or the like, and then extracted with water.

To describe the operating method in this case in more detail, the stereoregular polymer is extracted as an insoluble portion from the slurry extracted with water by a method such as 1 filtration, and the polymerization medium in which the atactic polypropylene is dissolved is The polymerization medium is removed by a method such as evaporation, and the machinable atactic polypropylene is produced in a state in which there is relatively little catalyst residue, and the halogen content is usually 100 to 300 Ppm.

On the other hand, with the recent improvement in catalyst performance, the stereoregular polymer can be removed by simply removing the medium and the atactic polypropylene soluble in the medium by filtering the stereoregular polymer without solubilizing the catalyst residue or extracting it with water. It is becoming possible to provide stereoregular polymers that can be used for various applications. In addition, in the bulk polymerization method using propylene itself as a medium without using an inert medium, the amount of polymer obtained on the catalyst is larger than when using the above-mentioned inert medium, so it is difficult to use alcohol etc. It is known that a product with less catalyst residue can be obtained by solubilizing the catalyst residue and then recovering the stereoregular polymer as a solid part by filtration or the like.

Although these methods can reduce the amount of catalyst remaining in the stereoregular polymer, soluble atactic polypropylene is usually recovered by removing the medium (inert medium or propylene) by evaporation. , the catalyst residue is concentrated in the atactic polypropylene.

Atactic polypropylene, which is abrasive in the production of stereoregular polypropylene or copolymers of propylene with other alpha-olefins or ethylene, is used (usually incinerated as a fuel or with other unsaturated bond-containing polymers). It is used for various purposes by blending it with a catalyst and then crosslinking it.When incinerating it as a fuel, if no special equipment is used, the remaining catalyst, especially the halogen content, can be reduced to an extremely small amount, e.g. sppm. (If the incinerator is not used, the incinerator may be damaged.Also, even when blended with other resins, it is preferable that the rogen content is low.)
It is desired that the content is 0 ppm or less, preferably 50 ppm or less.

The present inventors investigated a method for efficiently removing catalyst residue from atactic polypropylene, which contains a relatively large amount of catalyst residue, and found that it is possible to remove catalyst residue extremely easily by carrying out a specific treatment. They discovered this and completed the present invention.

An object of the present invention is to provide a method for removing catalyst residue from atactic polypropylene. The method of the present invention is also applicable to polymers containing a large amount of residual catalyst having a relatively low melting point.

The present invention is a method for purifying atactic polypropylene, which is characterized by bringing atactic polypropylene and aqueous ammonia into contact with each other while the atactic polypropylene is in a molten state.

There are no particular restrictions on the atactic polypropylene to which the method of the present invention can be applied, but the intrinsic viscosity measured in a tetralin solution at 135°C is 0.05 to 5.0, usually 0.1.
~3.0, and may contain comonomers such as ethylene, butene, butadiene, and isoprene in addition to propylene. In addition, the catalyst residual content is usually 30 to 2000
0ppm.

The halogen content is usually 30 to 20,000 ppms, and the chlorine content is 50 to 50,000 ppms.
Contains P 9m or more.

The ammonia water used in the contact treatment is one containing 1 mole or more of NH4OH per 1 gram atom of chlorine in the atactic polypropylene to be treated. The effect is not much different since only water is used.

For example, for atactic polypropylene 1f, 0.
1 to 100 g of ammonia water is used, and the preferred ratio is that if the chlorine content in the atactic polypropylene is large, a large amount of ammonia water should be used, and if the chlorine content is low, a small amount of ammonia water should be used. Not needed.

The contact treatment temperature may be any temperature higher than the melting temperature of atactic polypropylene and is usually carried out at 80 to 200°C.

The contact treatment time may be from 10 minutes to 10 hours, and the appropriate time is set depending on the shape of the stirrer and container.

There is no need to use hexane, heptane or kerosene during contact treatment.

It is also possible to include a suitable surfactant in order to improve the contact between the atactic polypropylene and the aqueous ammonia during the contact treatment.

No special method is required to separate the atactic polypropylene and aqueous ammonia after the contact treatment, and the aqueous ammonia layer can be separated by filtration after cooling or in a molten state.

By the above operation, residual catalyst, especially chlorine content, can be removed.
This makes it possible to provide atactic polypropylene for various uses, which is of great industrial significance.

EXAMPLES The present invention will be explained in further detail by way of Examples below.

Examples 1-2, Comparative Examples 1-2 Chlorine soooppm, total ash content 3.1 wt% (Mf O1
, Owt% JLz031.8wt%'l”101
aooppm) containing atactic polypropylene [intrinsic viscosity number 0.6 (measured with a tetralin solution at 135°C]) in a 2 L autoclave (with a stirrer) whose interior was lined with glass under the respective conditions shown in Table 1. The results are also shown in Table 1.

Example 3, Comparative Example 3 Chlorine 200 ppm, total ash 4 zoppm (MgOaop
The process was carried out in the same manner as in Example 1 under the conditions shown in Table 1 using an ethylene and propylene copolymer (ethylene content: 62 wt %, intrinsic viscosity: 1.4) containing (pmAj1203210Ppm). The results are also shown in Table 1.

Claims (2)

[Claims] (1) A method for purifying atactic polypropylene, which comprises bringing atactic polypropylene and aqueous ammonia into contact with each other while the atactic polypropylene is in a molten state. (2) Atactic polypropylene contains 50p of chlorine
The method according to claim 1, characterized in that the content is pm or more.