JPH0143763B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a process 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 other copolymers of α-olefin and propylene, is
It is removed from the product polypropylene because it impairs the physical properties of stereoregular polypropylene or other alpha-olefin and propylene copolymers. Removal of the by-product atactic polypropylene is
For example, in the solvent polymerization method using a polymerization medium, the stereoregular polymer is used as the polymerization medium insoluble part and the by-product atactic polypropylene is used as the polymerization medium soluble part. In that case, first, after the polymerization reaction, the catalyst residue is is often solubilized in alcohol or the like and then extracted with water to remove catalyst residues. To describe the operation 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 filtration,
On the other hand, the polymerization medium in which the atactic polypropylene is dissolved is removed by a method such as evaporation, and the atactic polypropylene is isolated.
In this case, the by-product atactic polypropylene has relatively little catalyst residue, and the halogen content is usually
It is 100-300ppm. On the other hand, with the recent improvement in catalyst performance, it is possible to remove the stereoregular polymer by simply removing the medium and the atactic polypropylene soluble in the medium by filtration 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. or,
In the bulk polymerization method, which uses propylene itself as a medium without using an inert medium, the yield of polymer per catalyst is larger than when using the above-mentioned inert medium, so alcohol etc. can be used to remove the catalyst residue. It is known that a product with less catalyst residue can be obtained by solubilizing the catalyst and then recovering the stereoregular polymer as a solid portion by filtration or the like. Although these methods can reduce the amount of catalyst residue in the stereoregular polymer, the soluble atactic polypropylene is usually recovered by evaporating off the medium (inert medium or propylene). Therefore, catalyst residues are concentrated in the atactic polypropylene. Atactic polypropylene, which is produced as a by-product during the production of stereoregular polypropylene or copolymers of propylene and other α-olefins or ethylene, is usually incinerated as fuel or combined with other unsaturated bond-containing polymers. It is used for various purposes by blending and then crosslinking. When incinerating it as a fuel, unless special equipment is used, the incinerator may be damaged unless the halogen content of the catalyst residue is kept extremely low, for example, 5 ppm or less. Even when blended with a resin, the halogen content is preferably low, preferably 100 ppm or less.
It is desirable that it be 50 ppm or less. The present inventors investigated a method for efficiently removing catalyst residues from atactic polypropylene, which contains a relatively large amount of catalyst residues, and found that catalyst residues can be removed 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 residues from atactic polypropylene. The method of the present invention is also applicable to polymers containing large amounts of catalyst residues with relatively low melting points. That is, in the present invention, 0.1 to 100 g of ammonia water is added to 1 g of atactic polypropylene.
A method for purifying atactic polypropylene, which comprises contacting atactic polypropylene in a molten state and then cooling and filtering to separate ammonia water, or separating an ammonia water layer in a molten state. . The method of the present invention can be particularly preferably applied to purifying atactic polypropylene containing a large amount of catalyst residue. Catalyst residue as ash content is 30~20000ppm,
It is applied to atactic polypropylene containing about 30 to 20,000 ppm of halogen content, and is particularly effective when applied to polypropylene containing 50 ppm or more of chlorine content. There are no particular restrictions on the atactic polypropylene to which the method of the present invention can be applied;
It is usually 0.1 to 3.0, and may contain comonomers such as ethylene, butene, butadiene, isoptene, etc. in addition to propylene. As ammonia water used for contact treatment,
Chlorine content in atactic polypropylene to be treated 1
A substance containing 1 mole or more of NH ₄ OH per gram atom is used, and a large excess, for example 10000
Even if the amount is more than mol, ammonia water will only be used in vain and the effect will not be much different. It is preferable to use 0.1 to 100 g of ammonia water per 1 g of atactic polypropylene. As for the ratio of use, if the chlorine content in the atactic polypropylene is high, treat with a large amount of ammonia water, and if it is low, treat with a small amount of ammonia water. If used, atactic polypropylene can be purified without wasting ammonia water. The contact treatment temperature should be at least the melting temperature of atactic polypropylene, usually 80 to 200
°C is appropriate. The contact treatment time may be from 10 minutes to 10 hours, and the time is appropriately set depending on the shape of the stirrer and container. During contact treatment, hexane, heptane, kerosene,
Although toluene, xylene, etc. may be present, they need to be removed after the contact treatment, and there is no particular need for these solvents to be present. 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 ammonia water after the contact treatment, but it is important to separate the ammonia water and liquid ammonia water. Preferably, the aqueous layer is separated. The above operation allows removal of catalyst residues, especially chlorine content, and 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 8000 ppm, total ash 3.1 wt% (MgO 1.0 wt%,
Autoclave ₂ (with a stirrer) made of atactic polypropylene [intrinsic viscosity number 0.6 (measured with tetralin solution at 135°C)] containing 1.3 wt% Al ₂ O 3 and 300 ppm TiO ₂ and lined with glass inside.
The samples were treated under the conditions shown in Table 1. The results are also shown in Table 1. Example 3, Comparative Example 3 Chlorine 200ppm, total ash 420ppn (MgO80ppm,
A copolymer of ethylene and propylene (ethylene content: 62 wt%, intrinsic viscosity: 1.4) containing Al ₂ O ₃ (210 ppm) was treated in the same manner as in Example 1 under the conditions shown in Table 1. The results are also shown in Table 1. 【table】

Claims (1)

[Claims] 1 For 1 g of atactic polypropylene
It is characterized by contacting atactic polypropylene with 0.1 to 100 g of ammonia water in a molten state, then cooling and filtering to separate the ammonia water, or separating the ammonia water layer in the molten state. Method for purifying atactic polypropylene. 2 Atactic polypropylene contains 50ppm of chlorine
The method for purifying atactic polypropylene according to claim 1, which contains the above.