JP2002317011A - Method for producing chlorinated vinyl chloride-based resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a chlorinated vinyl chloride-based resin simple in removing hydrogen chloride and good in coloring a molded product in a gas-solid catalytic chlorination method excellent in simplicity of after treatments and advantageous in a facility cost. SOLUTION: This method for producing the chlorinated vinyl chloride-based resin is to react a powdery vinyl chloride-based resin containing partially saponified polyvinyl acetate with a steam-containing chlorine gas in a gas-solid contact field, further, treat the obtained chlorinated vinyl chloride-based resin to remove hydrogen chloride by vacuum deaeration treatment and/or air cleaning treatment.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a molded article having a simple post-treatment such as washing, drying and waste liquid treatment by reacting a vinyl chloride resin with chlorine containing water vapor in a gas-solid contact field. This is a technique for producing a chlorinated vinyl chloride-based resin with less coloring.

[0002]

2. Description of the Related Art A chlorinated vinyl chloride resin obtained by post-chlorination of a vinyl chloride resin has excellent heat resistance, flame retardancy,
It has mechanical strength and electrical properties and is used in various industries. For example, the glass transition temperature of a normal vinyl chloride resin is about 80 ° C., but the glass transition temperature of a chlorinated vinyl chloride resin increases with an increase in the chlorine content,
Reaches 120-130 ° C. The Vicat softening temperature also shows a high value of about 120 ° C. Due to such high heat resistance, chlorinated vinyl chloride resins are used for heat-resistant pipes, heat-resistant joints, heat-resistant valves, heat-resistant sheets and the like.

[0003] An industrial production method of a chlorinated vinyl chloride resin has two steps: a step of polymerizing a vinyl chloride monomer to obtain a vinyl chloride resin, and a step of post-chlorinating the vinyl chloride resin. Consists of In the former polymerization step, a suspending agent mainly composed of partially saponified polyvinyl acetate was used as a suspending agent,
A method of synthesizing a suspension polymerization method is generally used.

[0004] In the latter post-chlorination step, a water suspension chlorination method has been mainly used. In the water suspension chlorination method, an aqueous suspension of a vinyl chloride resin having a solid content of several% to several tens% is filled in a reaction vessel, and chlorine is supplied while stirring the aqueous suspension. This is a method of performing a reaction. Furthermore, since the chlorination reaction does not proceed at all or is very slow by itself, light, heat, a catalyst, etc. are added to the aqueous suspension to promote the reaction. In the water suspension chlorination method, particles are easily stirred and mixed, the reaction control is easy because low-concentration chlorine dissolved in water is used, and vinyl chloride resin is plasticized with water. There are various advantages such as that chlorine easily penetrates into the resin. For this reason, the water suspension chlorination method has been adopted in many chlorinated vinyl chloride resin production facilities that have been put into practical use so far.

[0005] However, the water suspension chlorination method has a problem which cannot be essentially solved. In a reaction in which a chlorinated vinyl chloride resin is generated from the vinyl chloride resin and chlorine, hydrogen chloride is generated as shown in the formula (1). Therefore,
After completion of the reaction, the chlorinated vinyl chloride resin is suspended in a high-concentration hydrochloric acid solution.

[0006]

Embedded image The final shipping form of the chlorinated vinyl chloride resin must be in powder form, and it is necessary to remove hydrogen chloride as an impurity. The suspension must be dewatered, washed and dried. For this reason, the process of the water suspension chlorination method requires a large equipment cost for the post-treatment step, and the running cost associated with drying and washing with water increases. Moreover, since water and hydrogen chloride are in an azeotropic state, hydrogen chloride cannot be removed from the product until it is finally completely dried.

In the water suspension chlorination method, at the end of the reaction, the reaction solution becomes a high concentration hydrochloric acid solution of about 10% by weight. For this reason, in the water suspension chlorination method, it is necessary to use a titanium-based or titanium-palladium-based expensive corrosion-resistant metal material for the reaction apparatus, or use an apparatus having a surface treatment such as glass lining or fluorine lining. is there. Further, since the reaction solution having a high concentration of hydrochloric acid is carried into the above-mentioned post-treatment step, it is necessary to use an expensive corrosion-resistant material also in the post-treatment step.

As described above, the reactor for the water suspension chlorination method is
Although it is a device that is relatively simple in itself and easy to control, considering the entire process including the post-processing steps,
The apparatus has a disadvantage that a large load is imposed on equipment costs and running costs.

On the other hand, in order to make up for such a drawback of the water-suspended chlorination method, a chlorine-containing chlorination method using a gas-solid contact chlorination method using a gas-solid contact field between powder particles of a vinyl chloride resin and chlorine as a reaction field. A method for synthesizing a vinyl chloride resin has also been proposed. In the gas-solid contact chlorination method, the generated hydrogen chloride is discharged from the system as a gas, so the hydrogen chloride remaining after the reaction is adsorbed on the surface of the powder particles as well as those existing in the gaps between the powder particles. Hydrogen chloride only. Such residual hydrogen chloride can be easily removed by degassing the inside of the system in a vacuum or by circulating a gas such as air or nitrogen to wash the air. Therefore, water-washing /
A product having a low residual hydrogen chloride content as an impurity can be obtained without going through complicated steps such as dehydration and drying.

Further, in the gas-solid catalytic chlorination method, the reaction is usually carried out in a state where no water is present in the reaction system or a small amount of water is adsorbed on the powder particles. In such an anhydrous or slightly water system, the corrosiveness of chlorine and hydrogen chloride to the metal material is weak, and a relatively inexpensive nickel, stainless, or iron metal material can be used for the reactor. Furthermore, since only trace amounts of chlorine and hydrogen chloride remain in the powder particles brought into the post-processing step, inexpensive metal materials can be used in the post-processing step.

As described above, the gas-solid contact chlorination method of reacting a powder layer of a vinyl chloride resin with chlorine has excellent characteristics in terms of equipment cost, wastewater treatment, and safety.

On the other hand, according to the study of the present inventor, the chlorinated vinyl chloride resin obtained by the gas-solid contact chlorination method is heat-molded or press-molded, and the molded product is thermally denatured and colored. There is a problem that it is easy.

From the viewpoint that the chlorinated vinyl chloride resin is liable to be colored due to the non-uniformity of the reaction in the gas-solid contact reaction method, an improvement method has been proposed. For example,
Since the non-uniformity of the reaction in the gas-solid reaction method is due to the fact that the light that is the radical generation source is not uniformly irradiated on the vinyl chloride resin, the method for determining the radical generation source other than light energy is there. JP-A-59-247
The method 05 is a method in which a small amount of oxygen is mixed into chlorine to promote chlorination of the vinyl chloride resin in the absence of light. Japanese Patent Publication No. 60-2322 discloses that a vinyl chloride resin is impregnated with chlorine under high pressure and low temperature and then heated to generate thermal radicals in the vinyl chloride resin to obtain a chlorinated vinyl chloride resin. Is the way. However, in these methods, the reaction time is long, and the obtained chlorinated vinyl chloride resin has a low reaction rate and the quality problem has not been sufficiently solved. On the other hand, also in a method using light as a radical generation source, a method for improving the quality of a chlorinated vinyl chloride resin has been proposed. In Japanese Patent Publication No. 54-39878, a light source is inserted into a powder bed of a fluidized bed reactor, and a solution that blocks light in a wavelength range not involved in the reaction is circulated around the light source, and vinyl chloride is generated by the heat of the light source. There has been proposed a method for preventing deterioration of a system resin. However, in such a method, since the light source is inserted into the powder layer of the vinyl chloride resin, light is irradiated only to the vicinity of the light source, and the powder layer is hard to be uniformly chlorinated. In particular, in order to improve the chlorination non-uniformity in the production equipment scale equipment, it is necessary to insert a large number of light sources into the powder bed,
Unrealistic. In Japanese Patent Publication No. 52-15638, the powder layer, in which a light source is inserted, is fluidized with chlorine gas at a constant flow rate or more to widen the powder particle interval, thereby making the powder layer opaque and reaching the inside of the powder layer. Light is allowed to reach.
However, even with such a method, it is necessary to insert a large number of light sources into the powder layer, and the powder layer scatters at the superficial velocity at which the powder layer becomes opaque, and a powder layer recovery facility is installed. In addition, equipment for supplying a large amount of toxic and highly corrosive chlorine gas is required. Such a device has disadvantages that the equipment cost is high, the maintainability is low, and the reaction rate of passing chlorine is extremely low.

As another method for reducing coloring during molding,
A method of using a specific suspending agent when polymerizing a vinyl chloride resin as a raw material has been proposed. For example, JP
3-166205 proposes a method of improving the color tone of the obtained chlorinated vinyl chloride resin by post-chlorinating a vinyl chloride resin polymerized using hydroxypropylmethyl cellulose as a suspending agent by a water suspension chlorination method. ing. In addition, Japanese Patent Application Laid-Open Nos. 5-186507 and 5-18
No. 6520 discloses a method of post-chlorinating a vinyl chloride resin polymerized by using a cellulose suspending agent in combination with sodium alkyl sulfosuccinate or sodium alkyl diphenyl ether sulfonate. JP-A-63-1
08004, JP-A-62-284103 and JP-A-62-2
As described above, a copolymer obtained by polymerizing vinyl chloride and an olefin such as ethylene or propylene using a cellulosic suspending agent is post-chlorinated, whereby a resin having a low coloring property can be obtained. A way to obtain it has also been proposed. Furthermore,
JP-A-4-106110 discloses a method of post-chlorinating a vinyl chloride resin polymerized using polyethylene oxide as a suspending agent.
No. 08 describes a method of post-chlorinating a vinyl chloride resin polymerized by using polyethylene oxide and cellulose ether as a suspending agent.

However, the method of limiting the vinyl chloride resin used as a raw material is disadvantageous from the viewpoint of production flexibility. For example, vinyl chloride resin, which is a raw material for chlorinated vinyl chloride resin, is supplied by various companies. From the viewpoint of transportation costs and purchasing at competitive prices, it is better not to limit the type of vinyl chloride resin. It is advantageous. Further, the chlorinated vinyl chloride resin often requires various physical properties other than the coloring property at the time of molding, and it is difficult to freely select the type of the suspending agent.

[0016]

As described above, the present inventors have found that the chlorinated vinyl chloride resin obtained by the gas-solid catalytic chlorination reaction has an extremely important problem of the coloring property of the molded product. This proved to be a major issue for the practical application of the solid contact chlorination method.

An object of the present invention is to provide a method for obtaining a chlorinated vinyl chloride resin having good coloring properties of a molded product in a gas-solid contact chlorination method excellent in simplicity of post-treatment and facility cost. It is in.

[0018]

Means for Solving the Problems The present inventor studied the coloring mechanism for the purpose of improving the coloring property of a molded article of a chlorinated vinyl chloride resin obtained by a gas-solid contact chlorination method, The cause of the coloration was found to be due to the acetic acid groups of the partially saponified polyvinyl acetate. As a result, it is possible to improve the colorability of the molded product by hydrolyzing the acetic acid groups contained in the vinyl chloride resin by causing the chlorine containing the water vapor and the vinyl chloride resin to react in a gas-solid contact field and reacting. And completed the present invention.

That is, the first aspect of the present invention is characterized in that (1) reacting a powdery vinyl chloride resin containing partially saponified polyvinyl acetate with chlorine gas containing water vapor in a gas-solid contact field. The present invention relates to a method for producing a chlorinated vinyl chloride resin. (2) The method for producing a chlorinated vinyl chloride resin according to claim 1, wherein the chlorine gas is a chlorine gas containing water vapor having a pressure equal to or lower than a saturated water vapor pressure at the temperature inside the reactor (claim 2). (3) The chlorinated vinyl chloride resin according to claim 3, wherein the chlorine gas containing water vapor having a pressure equal to or lower than the saturated water vapor pressure is chlorine gas passed through an aqueous phase and / or a water droplet phase lower than the internal temperature of the reactor. The present invention relates to a manufacturing method (claim 3). (4) The method for producing a chlorinated vinyl chloride resin according to any one of claims 1 to 3, wherein light is used for accelerating the chlorination reaction. (5) The method for producing a chlorinated vinyl chloride resin according to claim 4, wherein the light source for promoting the reaction is at least one selected from a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a metal halide lamp. 5).

A second aspect of the present invention is: (6) dehydrogenation of the chlorinated vinyl chloride resin obtained by the method according to any one of claims 1 to 5 by vacuum degassing treatment and / or air washing treatment. The present invention relates to a method for producing a chlorinated vinyl chloride resin, which is characterized by being subjected to a treatment (claim 6).

The third aspect of the present invention relates to (7) a chlorinated vinyl chloride resin obtained by the method according to any one of claims 1 to 6 (claim 7).

[0022]

DETAILED DESCRIPTION OF THE INVENTION In the present invention, a reaction in which a solid present in a continuous phase of a gas containing chlorine gas is chlorinated is called gas-solid catalytic chlorination. The chlorine gas adsorbs on the surface of the vinyl chloride resin or diffuses into the vinyl chloride resin to react with the resin. In the present invention, since a chlorine gas containing water vapor is used, there is a possibility that an aqueous phase film is generated on the surface of the vinyl chloride resin. When chlorine gas comes into contact with a vinyl chloride resin via such an aqueous phase, there is a concept that the reaction is not strictly called a gas-solid contact reaction. This is called a solid contact chlorination reaction. In other words, a reaction in which the aqueous phase is not a continuous phase and is adsorbed on the surface of the vinyl chloride resin or is present in the gas phase as water vapor is called a gas-solid contact reaction. Distinguish from the aqueous suspension reaction method which is in phase.

The mechanism by which a molded article of a chlorinated vinyl chloride resin obtained by a gas-solid contact chlorination method is colored will be described. Since partially saponified polyvinyl acetate is a high-performance and low-cost dispersant, partially saponified polyvinyl acetate is used for suspension polymerization of many vinyl chloride resins. The partially saponified polyvinyl acetate is obtained by modifying a part or most of an acetic acid group to a hydroxyl group by saponifying polyvinyl acetate, and is generally called a partially saponified product of polyvinyl alcohol. The acetic acid group contained in the partially saponified polyvinyl acetate is a functional group that is more reactive than the hydroxyl group. Therefore, when chlorinated vinyl chloride containing an acetic acid group is heated, the chlorinated vinyl chloride and the acetic acid group cause some reaction, and the main chain in the chlorinated vinyl chloride is cut or a double bond is formed. It is known that when a double bond is formed in a part of the main chain, a double bond is continuously formed in a vinyl chloride resin or a chlorinated vinyl chloride resin one after another (called a zipper reaction). Polymers with increased double bonds have a yellow to dark brown color. This is the coloring mechanism of the chlorinated vinyl chloride resin.

The reason why the use of chlorine containing steam in the gas-solid contact chlorination method improves the colorability of the molded product will be described. When chlorine containing water vapor is used, the water vapor is adsorbed on the surface of the vinyl chloride resin or diffuses into the resin. On the other hand, as described above, when chlorinating a vinyl chloride resin, a large amount of hydrogen chloride is generated by the reaction formula shown in the formula (1). Since the acetic acid groups in the partially saponified polyvinyl acetate are hydrolyzed (ie, saponified) in the presence of an acid catalyst and water, the partially saponified polyvinyl chloride contained in the chlorinated polyvinyl chloride during the chlorination reaction. The saponification of vinyl acetate proceeds. For this reason, the acetic acid group, which is a substance causing deterioration of the coloring property of the molded product, is reduced.

In the chlorination reaction, the vinyl chloride resin used in the present invention is preferably a flowable powder from the viewpoint of easy handling and uniform progress of the reaction. The powder as referred to in the present invention is an aggregate of particles that can move alone in a gas phase, and the size of each particle is approximately 10 μm or more and 2000 μm or less (average particle size is 50 to 500 μm). In range. The particle size distribution of the powder particles is preferably uniform from the viewpoint of enhancing the fluidity of the powder and allowing the reaction to proceed uniformly, and the absolute value of the particle size has a preferable range. Therefore, the powder layer of the vinyl chloride resin used in the present invention has a thickness of 50%.
It is preferably an aggregate of powder particles (average particle diameter of 100 to 300 μm) mainly having a particle diameter of not less than μm and not more than 500 μm. Each powder particle may be composed of a continuous phase of a vinyl chloride resin, or may be an aggregate of smaller primary particles.

In the present invention, a vinyl chloride resin can be used as long as it is a powder layer that can flow even if it contains moisture.
However, since the present invention is characterized in that water vapor is contained in the supplied chlorine gas, if the water content of the vinyl chloride resin is too high, drying and dehydrochlorination treatment after the chlorination reaction will result in water and hydrogen chloride. And the advantages of gas-solid catalytic chlorination are lost. Therefore, the water content in the powder layer is 5% by weight.
It is preferably less than.

The vinyl chloride resin used in the present invention is:
The one mainly synthesized by the suspension polymerization method is used. When a vinyl chloride resin is synthesized by a suspension polymerization method, fine particles of the vinyl chloride resin are dispersed in water, so that powder particles can be obtained only by drying. However, in this case, a continuous layer called a skin layer is formed on the surface of the powder particles,
This may impede the penetration of chlorine gas into the interior, resulting in a slow reaction rate or a non-uniform reaction rate in the radial direction of the powder particles. Therefore, it is also effective that the powder particles of the vinyl chloride resin used in the present invention are pulverized in advance before the post-chlorination reaction to break the skin layer before use.

The essence of the present invention is to hydrolyze an acetic acid group, which is a cause of deteriorating the colorability of a chlorinated vinyl chloride resin during molding. Therefore, the method of the present invention is also effective for chlorination of a vinyl chloride resin synthesized by a method other than the suspension polymerization method. Examples of the vinyl chloride resin synthesized by a method other than the suspension polymerization method include a vinyl chloride resin synthesized by a bulk polymerization method, a gas phase polymerization method, and an emulsion polymerization method. For example, the same effect as in the present invention can be obtained by pulverizing a vinyl chloride resin obtained by a bulk polymerization method or a gas phase polymerization method into a powder having the above-mentioned particle diameter range and then chlorinating the same. In addition, the vinyl chloride resin obtained by the emulsion polymerization method can be chlorinated after granulation into a powder having the above-mentioned particle size range before and after drying, for example, by using a spray dryer. is there.

The chlorine used in the present invention is not particularly limited as long as it is generally used industrially. However, since the presence of a large amount of oxygen in chlorine affects the thermal stability of the obtained chlorinated vinyl chloride resin and the coloring of the molded product, the concentration of oxygen contained in chlorine is 10%.
It is preferably at most 0 ppm, most preferably at most 20 ppm. Further, chlorine may be diluted with an inert gas such as nitrogen or argon in order to adjust the reaction rate or the reaction temperature.

The method for supplying chlorine in the present invention will be described. In the present invention, the state of chlorine supplied into the reactor for the post-chlorination reaction may be gas or liquid. Generally, chlorine used industrially is liquid chlorine sealed in a cylinder. Therefore, in the case of supplying gaseous gas, the liquid chlorine removed from the liquid chlorine cylinder may be vaporized in another container and then supplied to the reaction container. When supplying liquid chlorine into the reaction vessel, the liquid chlorine removed from the liquid chlorine cylinder may be vaporized in the reactor. The method of vaporizing chlorine in the reactor is preferable because it has the effect of heat of vaporization depriving the heat of reaction and mitigating a rise in temperature in the reactor. However, if the liquid chlorine comes into direct contact with the vinyl chloride resin, the surface structure and internal structure of the vinyl chloride resin may change, so the liquid chlorine comes into contact with the vinyl chloride resin before vaporizing in the reaction vessel. It is desirable to take measures to avoid this.

The method for containing water vapor in chlorine according to the present invention will be described. In the present invention, a general method can be used without limitation as long as the gas contains steam. For example, chlorine (liquid chlorine or chlorine gas)
And steam may be mixed directly, or chlorine may be passed through water (including hot water or hot water). Alternatively, water may be dropped using a scrubber or the like, and chlorine gas may be passed through the droplet. However, since it is not preferable that water vapor is condensed in the reaction apparatus including the reaction vessel and the front and rear pipes and that the flowability of the vinyl chloride resin powder is hindered, the amount of water vapor contained in chlorine is not preferable. Is preferably lower than the amount of saturated steam at the temperature inside the reactor. From the viewpoint that the amount of water vapor in chlorine is controlled to be lower than the amount of saturated water vapor in the reactor, a method in which chlorine is passed through an aqueous phase or water droplets is preferable, and the water temperature is lower than the temperature inside the reactor. Is more preferable.

In the present invention, the timing of adding water vapor to chlorine is arbitrary. However, if the chlorine does not contain water vapor at the beginning of the reaction, it is considered that the acetic acid group may react with the vinyl chloride resin before saponification, so that the water vapor is added to the chlorine at the beginning of the reaction. Good to be. From the start of the reaction to the end of the reaction, the steam may be continuously contained in chlorine, or steam may be contained for a certain period of time from the start of the reaction, and dry chlorine may be introduced in the latter half of the reaction. Further, the amount of water vapor may be gradually reduced from the start of the reaction. Stop adding steam in the latter half of the reaction,
As a method of reducing the amount of addition, the water contained in the resin can be evaporated by the heat of the reaction at the latter stage of the reaction. Finally, it is necessary to dry the synthesized chlorinated vinyl chloride resin powder, so the above method is preferable because the subsequent drying step is simplified.

In the method of post-chlorination of the vinyl chloride resin in the present invention, a conventionally known method can be used without limitation as long as a gas-solid contact reaction between the vinyl chloride resin and chlorine gas is utilized. . The most suitable method for the gas-solid contact reaction is a method in which a powdery solid (that is, a vinyl chloride resin) in a fluid state and a gas (that is, a chlorine gas) are mixed and reacted. The flowing state refers to all states in which the powder particles are moving or moving continuously or intermittently and continuously. As an example, there is a method using a fluidized bed in which a gas flows through a powder bed to move particles.
As a reactor other than a fluidized bed, a method used in a conventionally used powder reactor may be used, or a mixer, a stirrer, a combustion device, a drying device, a crushing device, a granulation device, or the like may be used. May be applied. Specifically, a container rotating type device such as a horizontal cylindrical type, a V type, a double cone type, a swing rotary type, a single-shaft ribbon type, a double-shaft paddle type, a rotary plow type, a twin-shaft planetary stirring type, It is preferable to use a mechanical stirring type device such as a conical screw type. For the specific shapes of these devices, see the Chemical Engineering Handbook (edited by the Society of Chemical Engineers, 6th revised edition, 87)
6). Among these apparatuses, for example, a container rotating type reaction apparatus as shown in FIG. 1 is capable of mechanically stirring all the powder particles in that the powder can be surely fluidized and uniformly exposed on the surface of the powder layer. It is more effective for the present invention than a device of a mold type or a fluidized bed type device.

In a normal state, the reaction rate between the vinyl chloride resin and the chlorine gas is extremely low. Therefore, it is necessary to mix the powdery vinyl chloride resin with the chlorine gas and to take measures for accelerating the reaction. As a method of accelerating the reaction, a method of irradiating light, a method of adding a catalyst, a method of applying heat, and the like can be used, and these can be used in combination. In particular, the method of irradiating light is suitable for the present invention because it has a high reaction promoting effect and can obtain chlorinated vinyl chloride having a high reaction rate.

The type of light source used in the present invention will be described. The role of light in the present invention is to excite chlorine to generate chlorine radicals and promote the chlorine addition reaction to the vinyl chloride resin. Since chlorine has an energy absorption band in a wide wavelength range from the visible region to ultraviolet light, various light sources such as sunlight and artificial light can be used in the present invention. Since chlorine has the strongest absorption band for ultraviolet light having a wavelength of 320 to 360 nm, it is preferable to use a light source containing a large amount of this wavelength range. Specifically, a light source that emits a large amount of ultraviolet light, such as a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a metal halide lamp, may be used. The light source can be covered with a transparent cover according to purposes such as protection of the light source and cooling. In this case, the material of the transparent cover is quartz,
Hard glass, a soft glass tube or the like can be used, but in order to effectively utilize the wavelength in the ultraviolet region effective for the chlorination reaction, it is preferable to use quartz or hard glass, and it is preferable to use quartz. Most preferred.

The inside and the surface of the particles of the chlorinated vinyl chloride resin obtained by the gas-solid contact chlorination method of the present invention contain unreacted chlorine and hydrogen chloride as a reaction product. In order to industrially use the obtained chlorinated vinyl chloride as a product, it is necessary to remove chlorine and hydrogen chloride. As a method for removing chlorine or hydrogen chloride, a chlorinated vinyl chloride resin after the post-chlorination reaction is stirred or a fluidized bed is formed in a vessel in which a gas such as nitrogen, air, argon, or carbon dioxide is circulated. Examples of the method include a gas washing method and a vacuum degassing method in which a container containing a chlorinated vinyl chloride resin after a post-chlorination reaction is vacuum degassed to remove chlorine and hydrogen chloride. In order to enhance the effect of dehydrochlorination, horizontal cylinder type, V type,
Container rotation type devices such as double cone type and swing rotation type, single axis ribbon type, double axis paddle type, rotating plow type, twin axis planetary stirring type,
Use a mechanical stirring type device such as a conical screw type, etc.
It is advisable to circulate gas in the reaction vessel or to degas in a vacuum. The specific shapes of these devices are described in Chemical Engineering Handbook (edited by the Society of Chemical Engineers, 6th revised edition, p. 876). In addition, in order to omit the equipment for the dehydrochlorination step and to reduce equipment costs, after the end of the gas-solid catalytic chlorination reaction,
With the chlorinated vinyl chloride resin in the reactor, a cleaning gas can be passed or vacuum degassing can be performed.

[0037]

EXAMPLES Next, the method of the present invention will be specifically described with reference to examples. However, the present embodiment does not limit the present invention.

EXAMPLE 1 400 parts of ion-exchanged water, 0.005 parts by weight of polyethylene oxide having an average molecular weight of 2,000,000, and a partial saponification having a saponification degree of 80% were placed in a stainless steel autoclave equipped with a stirring blade. 0.0% polyvinyl acetate
5 parts by weight, 0.05 parts by weight of a 70% strength solution of di-2-ethylhexylperoxydicarbonate in isoparaffin were charged, and the inside of the autoclave was degassed under vacuum. 100 parts by weight were charged. Thereafter, suspension polymerization was carried out with stirring to obtain a suspension of a vinyl chloride resin having a degree of polymerization of about 1,000. The suspension of the vinyl chloride resin was dehydrated and dried to obtain a powdery vinyl chloride resin containing partially saponified polyvinyl acetate.

Using the apparatus shown in FIG. 1, post-chlorination of a vinyl chloride resin was carried out by a gas-solid contact reaction. Reaction vessel (1000 ml hard glass eggplant-shaped flask)
187.58 g = 3 mol of powder of vinyl chloride resin
Was charged. While the reaction vessel was immersed in a warm bath at 30 ° C. and rotated, nitrogen gas was passed through the space portion of the reaction vessel at a flow rate of 200 ml / min for 60 minutes, and chlorine gas was further passed at a flow rate of 200 ml / min for 30 minutes. Then, the flow rate of chlorine gas was increased to 600 ml / min, and 35 c
The surface of the powder layer was irradiated with ultraviolet rays using a 400 W high-pressure mercury lamp installed at a distance of m. At this time, the nitrogen gas and the chlorine gas passed through an aqueous phase at room temperature (about 30 ° C.). The reaction starts when the mercury lamp is turned on, and a mixed gas of chlorine and hydrogen chloride is discharged from the gas outlet. The generated hydrogen chloride was absorbed in water, and the hydrogen chloride generation amount and the chlorine content of the chlorinated vinyl chloride resin were continuously calculated from the neutralization titration value of the hydrochloric acid. When a thermocouple was inserted into the powder layer and the temperature of the powder layer was measured, the reaction started and the reaction heat was generated after the mercury lamp was turned on. Reached. Since the reaction rate decreases as the reaction proceeds, when the chlorine content reaches 60.3% by weight, the temperature of the warm bath is set to 45 ° C., and the chlorine content is 62.6% by weight.
, The temperature of the warm bath was raised to 60 ° C. When the chlorine content reaches 66.8% by weight, the mercury lamp is turned off,
The reaction was terminated.

After completion of the reaction, while keeping the temperature of the reaction vessel at 60 ° C., dry nitrogen gas not passing through the aqueous phase was passed through the reaction vessel at a flow rate of 600 ml / min to remove residual chlorine and hydrogen chloride. It was washed away. The thing which continued nitrogen flow for 100 minutes was used as the sample of the chlorinated vinyl chloride resin. Comparative Example 1 The same vinyl chloride resin as in Example 1 was subjected to a post-chlorination reaction using the reactor shown in FIG. A reaction vessel (a hard glass eggplant-shaped flask having a capacity of 1000 ml) was charged with 187.72 g = 3 mol of a vinyl chloride resin. While the reaction vessel was immersed in a warm bath at 30 ° C. and rotated, nitrogen gas was passed through the space portion of the reaction vessel at a flow rate of 200 ml / min for 60 minutes, and chlorine gas was further passed at a flow rate of 200 ml / min for 30 minutes. Then, add chlorine gas to 60
The pressure was increased to 0 ml / min, and the surface of the powder layer was irradiated with ultraviolet rays using a 400 W high-pressure mercury lamp installed at a position 35 cm away from the upper surface of the powder layer. The reaction starts when the mercury lamp is turned on, and a mixed gas of chlorine and hydrogen chloride is discharged from the gas outlet. When a thermocouple was inserted into the powder layer and the temperature of the powder layer was measured, the reaction started after the mercury lamp was turned on and reaction heat was generated. 51 ° C. was reached. When the chlorine content reaches 61.3% by weight, the temperature of the warm bath is set to 45 ° C., and when the chlorine content reaches 64.2% by weight, the temperature of the hot bath is reduced to 60%. ° C. When the chlorine content reached 66.8% by weight, the mercury lamp was turned off to terminate the reaction.

After completion of the reaction, while keeping the temperature of the reaction vessel at 60 ° C., dry nitrogen gas was passed through the reaction vessel at a flow rate of 600 ml / min to wash and remove residual chlorine and hydrogen chloride. A sample which was continuously purged with nitrogen for 100 minutes was used as a comparative sample.

The final chlorine content of the sample and the comparative sample was calculated from the change in weight before and after the reaction. That is, the chlorine content of the vinyl chloride resin was set to 56.8% by weight, and the change in weight of the powder resin before and after the reaction was calculated on the assumption that hydrogen in the vinyl chloride resin was replaced by chlorine. As a result, the chlorine content of the sample of Example 1 was 67.1% by weight, and the chlorine content of the sample of Comparative Example 1 was 66.8% by weight.

The method for evaluating the coloring property of the molded product of each sample during molding is described below. To 100 parts by weight of a sample, 10 parts by weight of MBS (B31 manufactured by Kanegafuchi Chemical Co., Ltd.), 2 parts by weight of a tin-based stabilizer, and 1.7 parts by weight of a lubricant were blended, and the mixture was rolled at 195 ° C. with an 8-inch roll. For 3 minutes.
The obtained sheet was pressed at 200 ° C. for 10 minutes to obtain a test piece. The color of the surface of the obtained test piece was measured for L value using a color difference meter (manufactured by Minolta, CR-200), and the coloring property of the molded product was evaluated. The L value is a value indicating the ratio of the reflected light from the test piece to the incident light. The larger the L value, the lower the coloring of the molded product and the better the coloring property. However, since the color of the test piece may change due to slight differences in the processing temperature and processing thickness, a comparative sample of the chlorinated vinyl chloride resin obtained by simultaneously pressing each sample in the same press machine was used. Standardized using L value = L ₀ . That is, the coloring property of the molded product was evaluated by the K value shown in the formula (2). The larger the K value, the less coloring of the molded product and the better the coloring property of the molded product.

K = L / L ₀ (2) Table 1 shows the results of Example and Comparative Example at the same time. From the results in Table 1, the chlorinated vinyl chloride resin obtained by reacting the chlorine gas containing water vapor by passing through the aqueous phase with the vinyl chloride resin by the gas-solid contact chlorination method passes through the aqueous phase. It can be seen that the coloring property at the time of molding is better than that of the chlorinated vinyl chloride resin obtained by reacting chlorine gas which is not allowed to react with the vinyl chloride resin.

[0045]

[Table 1]

[0046]

According to the method of synthesizing chlorinated vinyl chloride by the gas-solid contact chlorination method, by adding water vapor to chlorine, it is possible to produce a chlorinated vinyl chloride resin with less coloring of the molded product.

[Brief description of the drawings]

FIG. 1 is an apparatus diagram used in an example of a gas-solid catalytic chlorination reaction.

FIG. 2 is an apparatus diagram used for a comparative example of a gas-solid catalytic chlorination reaction.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Shun Wachi 3-3-2 Nishihata, Takasago City F-term (reference) 4J100 AC02Q AC03P BB01H CA01 CA31 DA22 DA47 DA55 HA21 HB00 HB04 HF05 JA15

Claims (7)

[Claims] 1. Production of a chlorinated polyvinyl chloride resin characterized by reacting a powdery vinyl chloride resin containing partially saponified polyvinyl acetate and a chlorine gas containing water vapor in a gas-solid contact field. Method. 2. The method for producing a chlorinated vinyl chloride resin according to claim 1, wherein the chlorine gas is a chlorine gas containing water vapor having a pressure not higher than the saturated water vapor pressure at the temperature inside the reactor. 3. The chlorine gas containing water vapor having a pressure equal to or lower than the saturated water vapor pressure is chlorine gas obtained by passing chlorine through a water phase and / or a water droplet phase lower than the internal temperature of the reactor. Production method of chlorinated vinyl chloride resin. 4. The method for producing a chlorinated vinyl chloride resin according to claim 1, wherein light is used to promote the reaction of the chlorination reaction. 5. The method for producing a chlorinated vinyl chloride resin according to claim 4, wherein the light source for promoting the reaction is at least one selected from a low-pressure mercury lamp, a high-pressure mercury lamp, an ultra-high-pressure mercury lamp, and a metal halide lamp. 6. The chlorinated vinyl chloride resin obtained by the method according to any one of claims 1 to 5, which is subjected to a vacuum degassing treatment and / or
Alternatively, a method for producing a chlorinated vinyl chloride-based resin, which is subjected to a dehydrochlorination treatment by a stream washing treatment. 7. A chlorinated vinyl chloride resin obtained by the method according to claim 1.