JPH0639492B2 - Improved chlorinated polyolefin manufacturing process. - Google Patents

Description

TECHNICAL FIELD The present invention relates to an improved process for producing chlorinated polyolefins.

(Prior Art) Currently, the production method of chlorinated polyolefin is the gas phase chlorination method,
A chlorination method in a solvent and a chlorination method in an aqueous suspension have been reported. The vapor phase chlorination method is not a general method due to reasons such as thermal stability of products, coloring, and limited applications.

In the chlorination method in a solvent, a relatively uniform chlorinated polyolefin can be obtained because it is chlorinated in an inert chlorine-based solvent mainly composed of carbon tetrachloride, but a low boiling point solvent is used at high temperature. There is a drawback that the reaction pressure becomes high because of the reaction, or that the reaction system becomes highly viscous in order to chlorinate the high molecular weight substance because the polyolefin dissolves and reacts, and the reaction must be performed at a low polyolefin concentration. This method is practiced in the production of solvent-soluble, relatively low molecular weight chlorinated polyolefins used in paints, adhesives and the like. In addition, carbon tetrachloride is becoming more difficult to use due to the problem of air pollution.

On the other hand, the chlorination method in an aqueous suspension performs a chlorination reaction by dispersing a powdered polyolefin in water, but the reaction system is a heterogeneous reaction, and unless the crystals of the raw material polyolefin are crushed by chlorination. It is desirable to carry out the chlorination reaction at a relatively high temperature because, for example, a uniform chlorinated product cannot be obtained, but this causes a blocking phenomenon of the polyolefin particles during the reaction.

Many attempts to use various dispersants have been reported as measures to prevent this. For example, polyvinyl alcohol, polyacrylic acid, a copolymer of maleic anhydride and methyl vinyl ether or styrene, polyacrylamide, polyvinylpyrrolidone, etc. are used (Japanese Patent Publication No. 46-21729, Japanese Patent Publication No.
47-7896, JP-A-54-124096, etc.). There is also an example of adding a surfactant. In the method reported so far, these dispersants and surfactants are dispersed in water and then the polyolefin is dispersed.Therefore, a lot of foaming occurs due to the initial stirring of the reaction, and the polyolefin particles are light and the water leakage property is poor, so the reaction vessel Floating a lot in the upper layer. Therefore, while being adhered in a strip shape to the gas-phase wall portion of the gas-liquid interface in the reaction tank, it is chlorinated, and the blocking substance is repeatedly desorbed and adhered. Also, because the polyolefin particles have poor water leakage,
If inhomogeneous particles remain in the initial stage and are chlorinated as they are, they will be included in the reaction product as perchlorates or coarse particles.
After completion of the reaction, these may cause insufficient cleaning of neutralization of hydrochloric acid and additives that have entered the blocking particles perchlorate particles during neutralization of by-product hydrochloric acid, resulting in coloring of the chlorinated polyolefin and deterioration of thermal stability. Connect It cannot be said that these problems have been sufficiently solved, and at present, in order to prevent blocking, chlorination is carried out at a temperature several tens of degrees lower than the melting point of the raw material polyolefin, or chlorination is stopped midway and the temperature is raised to the polyolefin melting point ( Annealing), and means for lowering the temperature and chlorinating again are reported.

Other methods have been reported to prevent blocking during chlorination by using inorganic or organic fine powder such as titanium dioxide, carbon black, talc, silica, polyvinyl chloride, etc. A large amount of additive remains, and it is not a practical method because it is subject to restrictions on the use of the product.

Generally, the chlorinated polyolefin obtained by the aqueous suspension method has a relatively large molecular weight of tens of thousands to hundreds of thousands and a chlorine content of 20 to
It is produced in a wide range from rubber-like to plastic-like performance at 50% by weight.

These applications are used for polymer blends of polyethylene, polypropylene, polyvinyl chloride, ABS resin, etc., or for molded products made of chlorinated polyolefin alone, and rubber-shaped molded products by crosslinking, and as a chlorinated polyolefin, they are as uniform as possible. It is desired to be chlorinated into fine particles and have excellent thermal stability.

(Problems to be solved by the invention) In view of the above points, the present invention is excellent in thermal stability by preventing blocking of polyolefin particles when chlorinating a polyolefin by an aqueous suspension method, and by uniform chlorination and high temperature reaction. It is an object of the present invention to provide a method for obtaining a chlorinated polyolefin.

(Means for Solving the Problems) In the present invention, when chlorinating a polyolefin by an aqueous suspension method, a powdery polyolefin as a raw material liquid is wet-treated with a water-soluble acrylic polymer-surfactant mixed liquid in advance. A method for producing an improved chlorinated polyolefin characterized by using a slurry liquid dispersed in an aqueous hydrochloric acid solution.

The polyolefin used in the present invention means powdery α-
An olefin homopolymer or copolymer such as polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, propylene-butene copolymer, ethylene-acrylic acid ester copolymer, ethylene-vinyl acetate copolymer. It is called a polymer, a polymer having a crystal structure such as an ethylene-butadiene copolymer. Particularly, polyethylene, ethylene-butene copolymer, ethylene-acrylic acid ester, vinyl acetate copolymer and the like are suitable.

The molecular weight of polyolefin is usually 10,000 to 1,000,
000, preferably 40,000 to 300,000 is suitable. The particle size of the polyolefin is not particularly limited, but since it is a heterogeneous chlorination reaction, it is preferable to be as fine as possible to obtain a uniform chlorinated product. Particles of 50 to 1000 μm are usually suitable.

The water-soluble acrylic polymer used in the present invention is a polymer of acrylic acid or acrylic acid ester or a copolymer thereof, or an alkali metal salt or ammonium salt of these polymers or copolymers and has a molecular weight of
It is preferably 3,000 or more, particularly 10,000 or more. The acrylic ester is preferably an alkyl ester having 1 to 4 carbon atoms. Among these polymers, those which can be water-soluble or can be colloidal dispersion are suitable for the present invention.

Examples of the surfactant include nonionic or anionic surfactants such as polyoxyethylene alkyl ethers, polyoxyalkylphenol esters, polyoxyethylene alkyl esters, sorbitan alkyl esters, ethylene oxide-propylene oxide block polymers and the like. Anionic activators such as nonionic activators, sodium alkylbenzene sulfonate, alcohol sulfates, alkyl sulfonic acids, alkylallyl sulfonic acids or their sodium salts are suitable.

The addition of an anion-active styrene polymer is also effective.

According to the chlorination by the aqueous suspension method currently reported and practiced, first, the dispersant and the surfactant are dissolved in water,
The chlorination reaction is carried out by dispersing powdered polyolefin in it, but due to the light weight of the polyolefin particles and poor water leakage, the polyolefin particles may float or collect in the upper layer of the reactor, and It adheres to the gas phase part of the liquid interface in a band shape, and the dispersibility becomes poor. These factors cause blocking during the reaction, and heterogeneous chlorinated compounds and perchlorinated compounds are mixed in the reaction product.

Also, as the chlorination reaction progresses, the system becomes hydrochloric acid by the by-product hydrochloric acid, and especially acrylic polymer precipitates and becomes particles and disperses throughout the system, so it is possible to obtain sufficient effect as a blocking inhibitor for polyolefin particles. If so, a large amount is required. On the other hand, the surfactant and the anion-active styrene polymer are uniformly dispersed even when the system becomes acidic with hydrochloric acid, but as the reaction progresses, the dispersibility decreases due to the action of by-product hydrochloric acid and hypochlorous acid. Come on. For this reason, a method of increasing the amount of the surfactant used or adding it in the middle of the reaction may be employed, but rather, the foaming of the reaction system becomes large, which is not preferable for the above reason.

The present inventors have found that the above acrylic polymer is completely dissolved in an aqueous system, but is insoluble and precipitated in an aqueous hydrochloric acid solution system,
A detailed study was conducted paying attention to the fact that it is effective in improving the water leakage of polyolefin and that it can be dissolved and removed in the neutralization washing step with an alkali even if the acrylic polymer is chlorinated. As a result, the powdery polyolefin was pre-wet with a water-soluble acrylic polymer-surfactant mixture, and dispersed in a 1 to 30 wt% hydrochloric acid aqueous solution,
The acrylic polymer can be effectively fixed on the surface of the polyolefin, and the surfactant dissolves in the hydrochloric acid aqueous solution to help disperse the polyolefin particles, thus preventing leakage,
A hydrochloric acid slurry solution of polyolefin having good dispersibility could be obtained.

The hydrochloric acid concentration in the hydrochloric acid aqueous solution is appropriately 1 to 30% by weight, but it is 3 to 25% because the concentration of hydrochloric acid as a by-product of the reaction increases.
Weight percent is preferred.

At this time, since the acrylic polymer alone has insufficient dispersibility, it is desirable to use a nonionic or anionic surfactant and an anionic styrene polymer in combination as the surfactant. However, the amount of surfactant used should be as small as possible in order to suppress foaming of the system.

The water-soluble acrylic polymer-surfactant mixture according to the present invention preferably has a solid content of 0.3 to 2.0% by weight of acrylic polymer, 0.1 to 2.0% by weight of surfactant, and 99.6 to 96.0% by weight of water. .

In the wet treatment of the polyolefin, 30 to 70 parts by weight of the mixed solution is sufficiently mixed with 100 parts by weight of the polyolefin by using a mixer such as a Henschel mixer or a ribbon mixer, and both are well blended. At this time, the wet state of the polyolefin is preferably a rice cake-like state from the state in which the polyolefin is completely wet, and it is an important point of the present invention that there is no excess water. If the water content is too high, the acrylic polymer is free. Is present and undesirable.

Then, the polyolefin is gradually added to the hydrochloric acid aqueous solution with stirring to obtain a finely dispersed polyolefin hydrochloric acid slurry liquid having good wettability.

The polyolefin concentration in the hydrochloric acid slurry liquid is preferably 3 to 20% by weight in consideration of stirring during the chlorination reaction. Furthermore, the hydrochloric acid slurry liquid of the polyolefin prepared in this way has very good thermal stability even when exposed to a high temperature (about 130 ° C) near the melting point of the polyolefin, and no abnormalities such as blocking or adhesion of the reactor wall occur. Absent. Further, the foaming was small even under stirring, and the polyolefin particles were in a good slurry state.

The method for chlorinating a polyolefin according to the present invention includes a chlorination reaction at a temperature lower than the melting point of a raw material polyolefin by 10 ° C. or more in order to avoid blocking of polyolefin particles as in the conventional method, or a reaction for performing a uniform chlorination. There is no need to change the temperature to 2 or 3 steps, or to perform annealing at the melting point of the polyolefin in the middle,
The chlorination reaction can be carried out in the range of ° C. For example 120-135 ℃
The chlorination reaction can be started from such a high temperature as above, and the temperature can be raised to 150 ° C by the reaction heat as the reaction progresses.

The slurry-like reaction product chlorinated to a predetermined chlorine content is taken out and separated into a reaction product and a reaction solution (hydrochloric acid aqueous solution). The reaction product is neutralized with a 10 to 48% by weight aqueous solution of caustic soda at room temperature to 100 ° C, then separated, washed with water at room temperature to 100 ° C, and dried to obtain a chlorinated polyolefin product. In addition, stearic acid or a salt thereof or the like can be added to prevent blocking properties of the obtained product.

(Effect of the invention) According to the present invention, by treating the surface of the polyolefin particles with a specific dispersion liquid, a good dispersion state is maintained during chlorination by an aqueous suspension method, and a uniform blocking phenomenon does not occur. Chlorination is possible. Therefore, since the polyolefin can be chlorinated at high temperature, the reaction rate becomes faster and the reaction time is greatly shortened. Since the heat history is not received for a long time due to the high temperature and short time reaction, fine particles that are almost equivalent to the uniformly chlorinated raw material polyolefin can be obtained. It becomes very good. Further, since the acrylic polymer fixed on the polyolefin is dissolved in the alkaline solution, it can be almost completely removed in the neutralization washing step. The same applies to the surfactant.

The chlorinated polyolefin obtained in this way has a much smaller amount of blocking substances and perchlorinated substances than that produced by the conventional method, is uniformly chlorinated, and is sufficiently neutralized and washed to be It is characterized by excellent stability.

The chlorination method according to the present invention is suitable for the production of a rubber-like chlorinated polyolefin from which polyolefin crystals are eliminated because it can be chlorinated at a high temperature.

(Example) The present invention will be described below with reference to Examples and Comparative Examples.

In the examples, composition% and parts are by weight.

Examples 1 to 4 Polyolefins such as polyethylene and polyethylene-butene copolymers shown in Table 1 were placed in a ribbon mixer, the dispersion liquid of Table 2 was gradually added under rotation stirring, and mixed at the ratio shown in Table 3. A uniform wet polyolefin was obtained.

This polyolefin was gradually added to the aqueous hydrochloric acid solution at a ratio shown in Table 3 with stirring to sufficiently disperse it.

Put the hydrochloric acid slurry liquid of the polyolefin prepared in this way into a 100-glass lined pressure reaction vessel, raise the temperature to a predetermined temperature under stirring, then air purge, and introduce chlorine gas to bring the chlorine content to 30-40%. The reaction was carried out as follows.

Chlorine gas was introduced from above the reaction vessel (upward blowing) or from the bottom (downward blowing). Almost no adhesion of chlorinated polyolefin to the inner wall of the reaction vessel after the reaction was observed. Table 3 shows the foaming state, blocking state, chlorination time, etc. during the reaction.

Next, the reaction product and the reaction solution (mixed solution of charged hydrochloric acid and by-product hydrochloric acid) are separated, and the reaction product is neutralized and washed with a total of 80 while stirring at 50 ° C. with a 20% aqueous caustic soda solution. 80
After washing with warm water of ° C, 1 part of calcium stearate was added to 100 parts of chlorinated polyolefin and dried. As a result, white fine powdery chlorinated polyolefin as shown in Table 4 was obtained.

Comparative Examples 1 and 2 Water and the dispersion liquid were charged into a glass lining pressure reaction vessel at a ratio shown in Table 3, and the polyethylene in Table 1 was gradually added with stirring. At this time, Comparative Example 1 has a large amount of foaming, and in Comparative Examples 1 and 2, the polyethylene is poor in wetness, so that it exceeds the upper layer portion and the dispersibility is poor.

Next, the temperature was raised to 110 ° C, and after air purging, chlorine gas was introduced from the upper part of the reaction vessel (upper blowing) to chlorinate to a chlorine content of 20%, the temperature was raised to 130 ° C without chlorine gas, and annealing was performed for 30 minutes. After that, the mixture was cooled to 120 ° C., and then chlorine gas was introduced again to carry out the reaction until the chlorine content was 35%. The initial reaction temperature was set to 110 ° C. because if the chlorination reaction is carried out at a temperature higher than this, a polyethylene blocking phenomenon will occur, which is not preferable.

After the completion of chlorination, a strip of polyolefin blocking material was adhered to the wall of the gas phase portion in the reaction vessel.

Neutralization with caustic soda was carried out by raising the neutralization temperature to 80 ° C because the chlorinated polyethylene particles blocked and the surface became hard due to the long thermal history of the reaction. The post-process is the same as in the example.

<Physical property test> The chlorinated polyolefins of Examples 1 to 4 and Comparative Examples 1 and 2 were used.
Knead with 2 rolls at 130 ℃ for 5 minutes, and cut out the sheet for 150 minutes.
Heat-pressed at 100 kg / cm ² for 10 minutes to form a 150 × 150 × 2 mm thick molded sheet. Table 4 shows the results of each physical property test performed on the above sheet.

As shown in Tables 3 and 4, Examples 1 to 4 had better wettability and dispersibility of polyolefin than Comparative Examples 1 and 2, and the slurry liquid was stable and the chlorination reaction proceeded even at a relatively high temperature. Neutralization with alkali was completed in a short time at low temperature, probably because the particles of the reaction product were fine and the particles were relatively porous due to the short heat history due to the short reaction time. .

Regarding the physical properties, Examples 2 and 3 and Comparative Examples 1 and 2 use the same polyethylene, and show substantially the same physical properties, but it is understood that Examples 2 and 3 according to the present invention are superior in thermal stability. .

Claims (2)

[Claims] 1. A slurry liquid prepared by subjecting a powdered polyolefin as a raw material liquid to a wet treatment with a water-soluble acrylic polymer-surfactant mixed liquid in advance when chlorinating the polyolefin by an aqueous suspension method and dispersing it in an aqueous hydrochloric acid solution. An improved process for the production of chlorinated polyolefins, characterized in that 2. The method according to claim 1, wherein the polyolefin is a homopolymer of α-olefin, a copolymer of α-olefin, or a copolymer of α-olefin and acrylic ester or vinyl acetate.