JPS62165B2 - - 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 a by-product during the production of stereoregular polypropylene or copolymers of propylene with other olefins, is removed from the product polymer because it impairs the physical properties of the stereoregular polymer. In the method of obtaining a stereoregular polymer by polymerization using a chlorine-containing catalyst, in the usual solvent method, the polymer slurry is treated with alcohol, water, etc. to remove catalyst residue, and then the product polymer is obtained as an insoluble part. It will be done. A solution of atactic polypropylene is obtained as the soluble portion, and the solvent is then removed by evaporation to obtain atactic polypropylene containing chlorine of 100 to 300 ppm, and in some cases less than 50 ppm. However, with recent improvements in catalyst performance, the method for removing catalyst residues from the produced polymer slurry has been simplified, and the catalyst residues can be simply solubilized in a solvent without washing with water, and can be removed from the solvent by a method such as filtration. It has become possible to obtain products by separation. In addition, in the polymerization method using propylene itself as a medium, since the amount of polymer obtained per catalyst is relatively large, it is necessary to solubilize the catalyst residue in propylene and then separate it from the medium by filtration to remove the propylene insoluble. You can get the product as part. Although it is possible to reduce the amount of catalyst residue in the product with the above method, on the other hand, the catalyst residue will be concentrated in the medium solution of atactic polypropylene after separation, so it is possible to simply remove this medium. If the catalyst is simply removed by evaporation, the resulting atactic polypropylene will contain a large amount of catalyst residue. Atactic polypropylene is used as a blend material with other resins or in adhesives, etc. However, if it contains a large amount of chlorine, its use is limited due to its corrosive nature, so it cannot be used as a non-corrosive comparison material. A method for obtaining atactic polypropylene free of physical impurities is desired. The present inventors investigated a method of processing atactic polypropylene with a relatively high chlorine content to obtain non-corrosive atactic polypropylene, and found that it is possible to obtain non-corrosive atactic polypropylene very easily by carrying out a specific processing method. They discovered that it is possible to obtain atactic polypropylene and completed the present invention. An object of the present invention is to provide a non-corrosive atactic polypropylene by treating atactic polypropylene containing a relatively large amount of chlorine. The present invention provides a method for obtaining non-corrosive atactic polypropylene by treating atactic polypropylene containing a relatively large amount of chlorine as a catalyst residue. It relates to a method for purifying atactic polypropylene, which is characterized by adding the present invention to atactic polypropylene at a certain ratio, carrying out a contact treatment at a temperature of 100° C. or higher, and then separating and removing insoluble portions from the atactic polypropylene. There are no particular restrictions on the atactic polypropylene to which the method of the present invention is applied;
Intrinsic viscosity measured with tetrane solution is 0.05~
5.0, preferably 0.1 to 3.0, and may contain comonomers such as ethylene, butene, butadiene, and isopropylene in addition to propylene. The catalyst residue contains a relatively large amount of chlorine, e.g.
Contains more than 1000ppm, and the ash content is 1000~
It contains about 50,000 ppm. Hydrotalcites used in contact treatment have the general formula Mg _1-x Al _x (OH) ₂ A _x mH ₂ O (where A represents a divalent anion, 0<x〓0.5, m〓0)
It is expressed as A _is usually ^CO2-3 or ^SO2-4 _{, preferably} ^CO2-3 . The usage ratio of hydrotalcites is 0.5 g or more, preferably 1 to 5 g per 1 g of chlorine,
If it is less than 0.5g, the corrosion resistance will be poor, and if it is more than 0.5g, the corrosion resistance effect will hardly change. The temperature of the contact treatment is 100° C. or higher, and the preferred temperature varies depending on the properties of the atactic polypropylene, but is usually higher than the softening point determined by the ring and ball method. In the contact treatment, it is preferable to achieve as good contact as possible, and it is preferable to use strong stirring means. The contact time should be set to an appropriate time depending on the above-mentioned contact means and the viscosity of the atactic polypropylene. Next, the insoluble portion is separated and removed from the atactic polypropylene subjected to the above contact treatment. This separation can be carried out by known methods such as filtration and decantation. By the above-mentioned operation, it is possible to obtain atactic polypropylene with good corrosion resistance, and it is of great industrial significance. The present invention will be explained in more detail with reference to Examples below. In the examples and comparative examples, the generated hydrochloric acid was
10 g of the solution was placed in a 100 ml flask, kept at 250°C, the generated hydrochloric acid or chlorine was entrained with nitrogen and absorbed into water, and the absorbed Cl ions were quantitatively measured. The corrosiveness is 2 cm x 10 cm, but the inner diameter of the copper plate is 3 cm.
Put 30% of the atactic polypropylene into a test tube.
The copper plate was heated in air at 200°C for 10 hours, and the degree of corrosion of the copper plate was visually determined. Atactic polypropylene with a chlorine content of 10 ppm and generated hydrochloric acid of 3 ppm was set as 1, and atactic polypropylene before treatment (chlorine content
1.2wt%, generated hydrochloric acid 400ppm) is set as 5,
Evaluation was made on a five-point scale. Examples 1 and 2: Comparative Examples 1 and 2: Atactic polypropylene with a chlorine content of 1.2 wt% (homopolypropylene, intrinsic viscosity number 0.23) 100
Add the additives shown in Table 1 using g and heat at 160℃.
The mixture was treated with stirring for 30 minutes, left to stand at 160°C for 2 hours, the transparent upper part was taken out, and the generated hydrochloric acid, corrosivity, and ash content were measured using the treated atactic polypropylene obtained. Comparative Example 1 shows the results for atactic polypropylene before treatment for comparison.

【table】

【table】

Claims (1)

[Claims] 1. A method for obtaining non-corrosive atactic polypropylene by treating atactic polypropylene containing a relatively large amount of chlorine as a catalyst residue, in which hydrotalcites are added per gram of chlorine.
A method for purifying atactic polypropylene, which comprises adding it to atactic polypropylene in a proportion of 0.5 g or more, carrying out a contact treatment at a temperature of 100° C. or more, and then separating and removing an insoluble portion from the atactic polypropylene. 2. The method of claim 1, wherein the contact treatment is carried out at a temperature equal to or higher than the softening point of the atactic polypropylene.