JPH0639491B2 - Method for producing chlorinated polyolefin and apparatus used therefor - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing a chlorinated polyolefin and an apparatus for producing the same.

(Prior Art) At present, chlorination in a solvent and chlorination in an aqueous suspension are commonly used as industrial processes for producing a chlorinated polyolefin.

The chlorinated polyolefin obtained by the chlorination method in a solvent is chlorinated while being dissolved in a solvent, and thus is relatively uniformly chlorinated, so that it can be dissolved in an aromatic or ketone organic solvent. However, since it reacts in an inert chlorine solvent such as carbon tetrachloride, when using a polyolefin with a high molecular weight, the viscosity of the reaction system becomes too high, so chlorination must be carried out at an extremely low polyolefin concentration. Generally, a raw material polyolefin having a molecular weight of about 10,000 or less is used. For this reason, the obtained chlorinated polyolefin becomes plastic and is mainly used for paints, adhesives and the like. Further, the use of carbon tetrachloride will be limited in the future due to the problem of air pollution.

On the other hand, in the chlorination method in an aqueous suspension, a powdered polyolefin is dispersed in water in which a dispersant or a surfactant is dissolved to carry out a chlorination reaction, but the reaction system is a heterogeneous reaction. It is desirable to carry out chlorination in the vicinity of the melting point of the polyolefin, because the crystal of the raw material polyolefin cannot be made into a uniform chlorinated product unless it is crushed by chlorination, but on the contrary, it causes a blocking phenomenon of the polyolefin particles during the reaction.

As measures for preventing this, currently reported methods include polyvinyl alcohol, polyacrylic acid, a copolymer of maleic anhydride and methyl vinyl ether or styrene, a dispersant such as polyacrylamide, polyvinylpyrrolidone, or the like.
A nonionic or anionic surfactant is dissolved in water in advance and used as a protective colloid, and then the powdered polyolefin is dispersed to carry out the chlorination reaction (Japanese Patent Publication No. 46).
-21729, Japanese Patent Publication No. 47-7896, JP-A No. 54-124096, etc.).

A cylindrical reactor equipped with a stirrer is generally used as a reaction vessel for chlorinating polyolefin by this aqueous suspension method, and its inner surface is a glass-lined iron reaction tank that is not corroded by chlorine gas, hydrochloric acid, etc. The one with a jacket for heating and cooling is used.

There is a method of introducing chlorine gas from the top or bottom of the reaction tank, and in either method, a predetermined amount of water, a dispersant, a surfactant, and a polyolefin are charged into the reaction tank in a batch system and chlorination is performed under stirring. Many methods have been reported for producing a chlorinated polyolefin by carrying out the reaction with a predetermined chlorination amount.

Dispersing the powdered polyolefin in an aqueous system in such a batch-type reaction tank is because the polyolefin is lightweight and has poor water-leakability and tends to float, so that uniform dispersion of the polyolefin is insufficient only by stirring in the tank. However, there are many problems, such as the problem of adhesion to the wall of the reaction tank and the generation of coarse particles and perchlorates due to non-uniform dispersion.

Perchlorates and coarse particles generated due to these blockings should be sufficiently neutralized and washed with hydrochloric acid and additives inside the hard particles and coarse particles during neutralization of by-product hydrochloric acid after the reaction. This causes the failure to perform, which leads to coloring of the chlorinated polyolefin and deterioration of thermal stability.

In order to solve these problems, currently reported methods include chlorination at a temperature of several tens of degrees lower than the melting point of the raw material polyolefin in a batch reactor, or stopping chlorine gas on the way to raise the temperature to the melting point of the polyolefin. Also, a means of lowering the temperature to chlorinate and uniformly react is taken, but it is not sufficient. The chlorination rate is low at a low temperature in proportion to the reaction temperature, and the chlorination rate is slow and the reaction time becomes long, which is not economically preferable.

Also, the solubility of chlorine in water and hydrochloric acid is very low,
Since it hardly dissolves at ℃, in a cylindrical reactor where polyolefin such as aqueous suspension reacts in a heterogeneous system or chlorine in the gas phase and polyolefin in the liquid phase are brought into contact to react. The reaction takes a long time.

In addition, a method to prevent blocking during chlorination by using fine powder of titanium dioxide, carbon black, talc, silica, polyvinyl chloride, etc. has been reported, but a large amount of these additives is contained in the reaction product. The rest is not practical because of restrictions on the use of the product.

Generally, chlorinated polyolefin produced by the aqueous suspension method has a large molecular weight of tens of thousands to hundreds of thousands and a chlorine content of 20 to 50% by weight.
Its characteristic is that it is produced in a wide range from rubber-like to plastic-like physical properties, and its applications are polyethylene, polypropylene, polyvinyl chloride,
It is used for polymer blends such as ABS resin or for chlorinated polyolefin alone, and is used for rubber-like molded products by cross-linking. As a chlorinated polyolefin, it is chlorinated as uniformly as possible and fine particles are excellent in thermal stability. What is desired is desired.

(Problems to be Solved by the Invention) In view of the above points, the present invention, when chlorinating a polyolefin by an aqueous suspension method, carries out a continuous chlorination reaction by using a tubular reactor, and a high temperature, short An object of the present invention is to provide a method for producing a chlorinated polyolefin excellent in thermal stability in a time period and an apparatus used for the method.

(Means for Solving the Problems) The present invention is to introduce a slurry liquid of a powdery polyolefin dispersed in an aqueous hydrochloric acid solution by a dispersant into a reaction tube and to react with chlorine while passing through the reaction tube. It is a characteristic chlorinated polyolefin production method and an apparatus used therefor.

The powdered polyolefin used in the present invention is a powdery α-olefin homopolymer or copolymer, for example, polyethylene, polypropylene, ethylene-propylene copolymer, ethylene-butene copolymer, ethylene-acrylic acid ester copolymer. It refers to a copolymer having a crystal structure such as a polymer, a propylene-butene copolymer, an ethylene-vinyl acetate copolymer, an ethylene-butadiene copolymer. In particular, a homopolymer of ethylene or a copolymer of ethylene and another α-olefin, vinyl acetate or acrylic ester is preferably used. The molecular weight of the polyolefin is usually 10,000 to 1,000,000, preferably 40,000 to 300,000.
The ones are suitable.

Although the particle size of the polyolefin is not limited, it is preferably as fine as possible because it is a heterogeneous chlorination reaction. In the present invention, particles of 50 to 1000 μm are usually suitable.

The dispersant in the present invention is meant to include a surfactant in addition to an acrylic polymer which is usually used as a dispersant. The water-soluble acrylic polymer is a polymer of acrylic acid or acrylic acid ester, a copolymer thereof, or an alkali metal salt or ammonium salt of these polymers or copolymers having a molecular weight of 3,000 or more, particularly 10,000 or more. preferable. 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 surfactants and anionic surfactants such as polyoxyalkyl ethers, polyoxyalkylphenol esters, polyoxyethylene alkyl esters, sorbitan alkyl esters, ethylene oxide-propylene oxide block polymers and the like. Suitable anionic activators, sodium alkylbenzene sulfonates, 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.

The above dispersants may be used alone or in combination by adding them to the slurry liquid, but there is a method in which the surface of the polyolefin is wet treated with a mixed solution of a water-soluble acrylic polymer and a surfactant. preferable. By dispersing the polyolefin treated in this way in an aqueous hydrochloric acid solution, the acrylic polymer can be efficiently fixed on the surface of the polyolefin particles, and the surfactant dissolves in the aqueous hydrochloric acid solution to help disperse the polyolefin particles. It is possible to obtain a hydrochloric acid slurry liquid of polyolefin having good properties and dispersibility.

The water-soluble acrylic polymer-surfactant mixture is a solid content of 0.3-2.0% by weight of acrylic polymer and 0.1% of surfactant.
A ratio of up to 2.0% by weight and water 99.6 to 96% by weight is preferable.

For 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 using a mixer such as a Henschel mixer or a ribbon mixer. At this time, the wet state of the polyolefin is preferably a mochi-like state from the state where the polyolefin is completely wet, and it is important to prevent excess water. If the water content is too large, a free acrylic polymer is present, and when acidified with hydrochloric acid, it is dispersed in an aqueous solution of hydrochloric acid and the effect is reduced, which is not preferable.

It is appropriate that the hydrochloric acid concentration in the hydrochloric acid aqueous solution is 1 to 30% by weight, but it is 3 to 35% because the by-product hydrochloric acid from the reaction increases the concentration.
Weight percent is preferred. The polyolefin concentration in the hydrochloric acid slurry solution is suitably 3 to 20% by weight.

The polyolefin hydrochloric acid slurry thus prepared has very good thermal stability even when exposed to a high temperature (about 130 ° C.) near the melting point of polyolefin, and blocking and adhesion to the reactor wall do not occur. Foaming under agitation was small and it was in a good slurry state.

In the present invention, the slurry liquid thus dispersed in the hydrochloric acid aqueous solution by the dispersant is introduced into the reaction tube to carry out the chlorination reaction.

1 and 2 illustrate an apparatus suitable for carrying out the method of the present invention. In the apparatus of FIG. 1, first, the powdered polyolefin (1) is put into the ribbon mixer (2), and then the water-soluble acrylic polymer-surfactant mixed liquid is added as the dispersion liquid (3) and mixed sufficiently. , Wet the polyolefin. This is added to a slurry adjusting tank (5) containing a hydrochloric acid aqueous solution (4) with stirring to form a uniform slurry. Then, the liquid is sent to the reaction tube (8) through the conduit (7) by the liquid sending pump (6).
The slurry liquid passing through the reaction tube (8) is previously heated by the steam (9), and chlorine (10) is introduced near the inlet of the reaction tube (8) and chlorinated. (11) and (12) are static mixers that improve the stirring of the slurry liquid, and (13) is a liquid feed pump. The slurry liquid in which the chlorination reaction is almost completed in such a reaction tube is introduced into the second adjusting tank (14) and the liquid is stirred to sufficiently react unreacted chlorine. This slurry liquid is continuously taken out by the pump (15), and the conduit (1
After 6), it is separated into a reaction product (chlorinated polyolefin) and a reaction solution (hydrochloric acid aqueous solution) by a machine, and the reaction product is neutralized with a 10 to 48 wt% caustic soda aqueous solution at room temperature to 100 ° C. After that, wash at room temperature to 100 ° C with water and dry to obtain a chlorinated polyolefin product.

In the apparatus of FIG. 2, the method of wetting and chlorinating the polyolefin is the same as that of FIG. 1, but the slurry liquid chlorinated by the reaction tube (8) is circulated through the conduit (17) to the adjusting tank (5). , A part of it is taken out by the conduit (18) and made into a product by the same process as in FIG.

The materials used in these devices are required to withstand high temperatures (about 150 ° C) without being corroded by chlorine or hydrochloric acid. For example, a glass-lined iron container or the like is suitable. The inner diameter of the reaction tube is determined according to need, but the circulated slurry should flow in a turbulent state rather than a laminar flow state in order to ensure sufficient contact between chlorine and the polyolefin, resulting in a turbulent flow state. Determine the pump capacity and reaction tube inner diameter in the same manner.

It is also very effective to install a static mixer, baffle plate, etc. in the middle of the reaction tube and conduit to improve the dispersion of chlorine and polyolefin.

The length of the reaction tube varies depending on the manufacturing scale, but it is 10 to 100 m.
If the length is enough, it can be chlorinated enough.

The temperature of the chlorination reaction with this equipment can be carried out at 80 to 150 ° C, but the chlorination reaction rapidly increases from around 110 ° C, so
It is preferable to carry out at 150 ° C. The method for introducing chlorine may be gaseous or liquid, and a device for press-fitting may be provided.

To heat the slurry liquid to be reacted, it is economical to directly introduce steam into the slurry liquid to raise the temperature, because the temperature rises quickly. Further, particularly when the reaction is started from 110 ° C. or higher, the temperature of the slurry liquid is raised by the heat of reaction, the chlorination rate is further increased, and the reaction proceeds.

In order to prevent the blocking property of the chlorinated polyolefin obtained through the steps of neutralization, washing and drying, stearic acid or its salt may be added in an amount that does not impair the use.

(Function) In the polyolefin chlorination reaction technique according to the present invention, the reaction time is several tenths to one hundredth of one hundred times that of the conventional batch type cylindrical reactor when the reaction tube is used. It is a major feature and advantage that it is greatly shortened. Moreover, even if a rapid chlorination reaction is carried out at high temperature, the reaction in the reaction tube can be easily controlled because the reaction is carried out in water with a large specific heat, and the reaction product has problems such as yellowing and alteration. There is no. Further, the chlorinated polyolefin obtained by the present invention is different from the conventional method in that the heat history during the reaction is produced within a very short time, so that the particles of the chlorinated polyolefin are relatively softer than those obtained by the conventional method. There is. This is because the chlorinated polyolefin by the conventional method is slowly chlorinated, so that only the particle surface is well chlorinated and a hard layer is easily formed.On the other hand, in the present invention, microscopically, a rapid chlorination reaction occurs on the polyolefin particle surface at high temperature. It is considered that a relatively soft chlorinated polyolefin can be obtained because the polyolefin is softened and the inside is more easily chlorinated.

In such a chlorination device, the polyolefin in the hydrochloric acid slurry liquid is almost chlorinated in the reaction tube and almost chlorinated in the place where it enters the second adjusting tank, and the pressure is also extremely low, so that the unreacted polyolefin is unreacted. Also, the chlorine content is small, and neither adheres nor blocks the vessel wall in the second adjusting tank. Further, since the polyolefin is constantly transferred or circulated in the reaction tube, it is possible to avoid unevenness in the reaction due to local retention such as a batch reaction, and it is possible to carry out a more uniform chlorination reaction.

Furthermore, since the chlorinated polyolefin according to the present invention is obtained in the form of uniform, fine and soft particles, the neutralization property of by-product hydrochloric acid with an alkali and the cleaning property with water are very good, and the neutralization cleaning is completed in a short time. Furthermore, since the used dispersant can be removed almost completely by washing, and a blocking substance, a perchlorate, etc. are hardly generated, a chlorinated polyolefin having excellent thermal stability can be obtained.

Since the chlorination method according to the present invention can smoothly perform high-temperature chlorination, it is suitable for producing a chlorinated polyolefin having a rubber-like property in which polyolefin crystals are eliminated.

(Example) Next, the present invention will be described in detail with reference to Examples and Comparative Examples. All composition percentages are weight percentages.

Examples 1 to 4 The polyethylene and ethylene-vinyl acetate copolymers shown in Table 1 were placed in a ribbon mixer, the dispersions shown in Table 2 were gradually added with stirring, and they were mixed sufficiently in the proportions shown in Table 3. The polyolefin was brought into a uniform wet state. This polyolefin was gradually added to an adjusting tank containing an aqueous hydrochloric acid solution at a rate shown in Table 3 with stirring to obtain a uniformly dispersed polyolefin hydrochloric acid slurry solution.

Continuous Chlorination Method In Examples 1 and 2, the reaction was carried out using the apparatus shown in FIG. That is, a hydrochloric acid slurry solution of polyethylene was made in a 100 glass lining preparation tank, and the slurry solution was heated to 90 ° C. and then pumped into a 1 ″ diameter glass lining conduit. Directly blow to heat the slurry liquid to 125 ° C, then introduce chlorine, and then chlorinate by flowing at a rate of 100 / min through a 20-meter reaction tube made of 1 ″ diameter glass lining with two static mixers arranged in two places. The reaction was carried out.

Next, in order to absorb unreacted chlorine content, it was put in a second adjusting tank made of 50 glass lining and reacted at 130 ° C. with stirring to obtain a target chlorine content, and this slurry liquid was taken out at a rate of 100 / min. The internal pressure of this second adjusting tank is 3kg / during the reaction.
It was cm ² .

The taken-out slurry liquid was continuously separated into a reaction product and an aqueous hydrochloric acid solution with a cloth, and the reaction product was neutralized and washed with a 20% caustic soda solution under stirring at 50 ° C, and then washed with warm water at 80 ° C. Next, 1 part by weight of calcium stearate was added to 100 parts by weight of chlorinated polyethylene and dried. As a result, white fine powder chlorinated polyethylene as shown in Table 4 was obtained.

Circulating chlorination method In Examples 3 and 4, the circulating chlorination method was performed using the apparatus shown in FIG.

That is, a hydrochloric acid slurry liquid of polyolefin was prepared in a 100 glass lining adjusting tank. This adjusting tank is equipped with a glass lining pipeline (conduit and reaction tube) with a diameter of 2 "from the bottom.
Three static mixers are arranged and circulated from the upper part to the adjusting tank. Stir the hydrochloric acid slurry solution of the polyolefin made in the adjusting tank,
The temperature was raised while circulating at a rate of 0 / min, and when the temperature reached 125 ° C, chlorine was introduced into the circulation, and the temperature was raised to 130 ° C by the heat of reaction due to chlorination to carry out the reaction. The internal pressure during chlorination was 3 kg / cm ² .

After the completion of the reaction, the reaction product is cooled and separated into an aqueous hydrochloric acid solution, and neutralized, washed and dried in the same manner as in Examples 1 and 2 to obtain a white fine powder chlorinated polyolefin shown in Table 4. It was

Comparative Example 1 Water and the dispersion liquid were charged into a 100-glass-lined cylindrical reaction container at the ratio shown in Table 3, and the polyethylene of Table 1 was gradually added with stirring. At that time, there is a lot of foaming and the wetting of polyethylene is bad, so that it is around the upper layer and the dispersibility is poor.

The chlorination reaction is carried out at 110 ° C to a chlorine content of 20%, then the temperature is raised to 130 ° C without chlorine gas, annealed for 30 minutes, cooled to 120 ° C, and then reacted again to a chlorine content of 35%. went. The reaction temperature is set to 110 ° C., because if the chlorination is started at a higher temperature, the blocking phenomenon of polyethylene occurs, which is not preferable. After the completion of the reaction, a polyethylene blocking material was adhered to the wall of the gas phase portion in the reaction vessel in a band shape.

Subsequent steps were similar to those in the previous example to obtain white fine powder chlorinated polyethylene.

Comparative Example 2 Polyethylene pretreatment was carried out in the same manner as in Examples 1 to 4 using the polyethylene of Table 1 and the dispersions of Table 2 at the ratios shown in Table 3.
Hydrochloric acid slurry was made in 100 glass lined cylindrical reaction vessels. Since this slurry has good dispersibility and excellent thermal stability, it undergoes a chlorination reaction at 125 ° C and has a chlorine content of 35
%. Chlorine gas was blown from the bottom of the reaction vessel. Almost no adhesion to the reactor wall was observed after the reaction was completed.
However, the reaction time is longer than in Examples 1 to 4 (see Table 3).

Subsequent steps were similar to those in the previous example to obtain white fine powder chlorinated polyethylene.

<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 dispense the dispensing sheet for 150 minutes.
Hot pressing was performed at 100 kg / cm ² for 10 minutes to produce a 150 × 150 × 2 mm thick molded sheet. Each physical property test shown in Table 4 was performed on the above sheet.

The results of each of the above Examples and Comparative Examples are summarized in Tables 1 to 4.

From the above results, the chlorination reaction of Examples 1 to 4 proceeded rapidly faster than that of Comparative Example, and the obtained chlorinated polyolefin products had fine particles and had a very short thermal history due to the short reaction time. Since it is time, the particles are soft and porous, and the neutralization with alkali is completed at a low temperature in a short time. In Comparative Example 1, the surface was hardened because the chlorinated polyethylene was slightly blocked and it was subjected to a heat history due to the reaction for a long time, and the neutralization temperature was raised to 80 ° C., but it took a long time.

In terms of physical properties, the same polyethylene was used in Examples 2 and 3 and Comparative Examples 1 and 2, and chlorinated polyethylene produced in a short time by a reaction tube was almost equivalent to that of the conventional method, but thermal stability In terms of sex, it is clear that the example is superior to the comparative example 1 in particular.

(Effects of the Invention) As described above, according to the present invention, a hydrochloric acid slurry liquid of polyolefin having a uniform and excellent dispersibility is prepared with a dispersant, and chlorination is carried out while passing the slurry liquid through a reaction tube. A chlorinated polyolefin in the form of fine particles and excellent in thermal stability can be obtained in a time period.

[Brief description of drawings]

The drawings are conceptual views illustrating an apparatus for carrying out the present invention. FIG. 1 shows a continuous chlorination apparatus, and FIG. 2 shows a circulating chlorination apparatus. (1) ... Polyolefin, (2) ... ribbon mixer, (3) ... dispersion, (4) ... hydrochloric acid aqueous solution, (5) ... adjustment tank, (8) ... reaction tube, (10) ... chlorine, (11) , (12)… Static mixer, (14)… Second adjusting tank

Claims (6)

[Claims] 1. A method for producing a chlorinated polyolefin, characterized in that a slurry liquid of a powdery polyolefin dispersed in a hydrochloric acid aqueous solution with a dispersant is introduced into a reaction tube and reacted with chlorine while passing through the reaction tube. . 2. The method for producing a chlorinated polyolefin according to claim 1, wherein a slurry liquid obtained by subjecting the powdered polyolefin to a wet treatment with a dispersant and dispersing it in an aqueous hydrochloric acid solution is used. 3. The method for producing a chlorinated polyolefin according to claim 1, wherein the dispersant is a water-soluble acrylic polymer-surfactant mixed solution. 4. The chlorinated polyolefin 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. Manufacturing method. 5. An adjusting tank for adjusting a slurry liquid of a powdery polyolefin, a conduit for introducing the adjusted slurry liquid to a reaction tube by a liquid sending pump, and a slurry liquid sent from the conduit having a chlorine inlet port. An apparatus for producing a chlorinated polyolefin, comprising: a reaction tube for reacting with chlorine while passing through; and a second adjusting tank for storing a chlorinated slurry liquid drawn out from the reaction tube. 6. An adjusting tank for adjusting a slurry liquid of a powdery polyolefin, a conduit for introducing the adjusted slurry liquid to a reaction tube by a liquid sending pump, and a slurry liquid sent from the conduit having a chlorine inlet port. Production of chlorinated polyolefin characterized by comprising a reaction tube for reacting with chlorine while passing through and a conduit for recirculating at least a part of the chlorinated slurry liquid derived from the reaction tube to the adjusting tank. apparatus.