JP2008038129A - Method for producing chlorinated vinyl chloride resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing a chlorinated vinyl chloride resin decreasing the hydrochloric acid concentration in the chlorinated vinyl chloride resin before drying, reducing the hydrochloric acid removal load in the following drying process, and reducing the problems such as the corrosion of a drier. <P>SOLUTION: The method for producing a chlorinated vinyl chloride resin comprises the addition of a hypochlorite to slurry of a chlorinated vinyl chloride resin or a hydrated resin during or after the process of separating an aqueous solution of hydrochloric acid by-produced from the chlorinated vinyl chloride resin slurry obtained by chlorinating vinyl chloride resin or a copolymer of vinyl chloride and other copolymerizable monomers. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a method for producing a chlorinated vinyl chloride resin by chlorinating vinyl chloride or a copolymer resin thereof.

  A chlorinated vinyl chloride resin (hereinafter referred to as “CPVC”) is one of general-purpose resins having excellent heat resistance. The heat resistance is more advantageous as the amount of chlorine (degree of chlorination) contained in the CPVC molecule is larger, and the following methods are generally used as its production method. That is, this is a method in which a vinyl chloride resin (hereinafter referred to as “PVC”) is suspended in an aqueous medium, and gaseous or liquid chlorine is supplied thereto to perform a chlorination reaction of PVC. Furthermore, among such chlorination methods, a photochlorination method using light (ultraviolet rays) and a thermal chlorination method using heat are industrially implemented. (Patent Document 1)

The reaction process of this chlorination reaction is considered to be composed of the following three processes.
(1) Cl ₂ → 2Cl. (Radical generation reaction)
(2) PVC + Cl · → PVC · + HCl (hydrogen abstraction reaction)
(3) PVC ・ + Cl ・ → CPVC (chlorination reaction)
(1) is a radical generation reaction in which chlorine is converted into chlorine radicals by light or heat, (2) is a hydrogen abstraction reaction in which hydrogen is extracted from PVC by chlorine radicals, and (3) is a polymer radical. This is a reaction in which CPVC is generated by (PVC.) And chlorine radical or chlorine. The reaction formulas (1) to (3) are collectively represented by the following reaction formula (A).
(A) PVC + Cl ₂ → CPVC + HCl

  Therefore, in the chlorination reaction as shown in (A), only about half of the raw material chlorine is used for the chlorination reaction and half is consumed as a by-product of hydrochloric acid. Therefore, the hydrochloric acid concentration in the slurry after the chlorination reaction is 5 to 12% by weight with respect to the moisture in the slurry, for example, and equipment corrosion of the reactor, dryer, etc. becomes significant, and is expensive to prevent equipment corrosion. It was necessary to take measures such as coating the equipment with a new metal. Therefore, in order to reduce the hydrochloric acid load of the dryer as much as possible, there has been an industrial problem that a large amount of water is required for the washing.

  For this purpose, it is advantageous in terms of cost to adopt a process of washing and removing hydrochloric acid in the resin with warm water, but this also causes the amount of hydrochloric acid before drying to be about 1,000 ppm, which removes hydrochloric acid in the drying step. In order to reduce the load, the concentration of hydrochloric acid before drying must be 100 ppm or less.

  Various efforts have been made to improve the hydrochloric acid load as much as possible. For example, a method using citric acid and various salts thereof to neutralize by-product hydrochloric acid has been proposed (Patent Document 2). Since these become impurities, the use and cleaning thereof are very expensive, and the residual amount of hydrochloric acid is difficult to be 100 ppm or less.

  Furthermore, although the method (patent document 3) of removing hydrochloric acid using a filtration apparatus is also proposed, even if this was used, it was difficult to make it 100 ppm or less.

  Furthermore, the chlorination reaction is not performed by blowing chlorine, but a method in which chlorine is generated by proton acid and hypochlorite (Patent Document 4) or hypochlorite is added during the chlorination reaction by chlorine. (Patent Document 5) has also been proposed. Although these methods can reduce the concentration of hydrochloric acid in water, it has been difficult to reduce the residual amount of hydrochloric acid in the resin to 100 ppm or less.

Thus, in the production of CPVC in the past, there are various industrial problems such as the problem of equipment corrosion due to hydrochloric acid in the slurry, the problem of initial colorability and a decrease in transparency, and technical development to improve these balances, It has long been a challenge for those skilled in the art.
Japanese Examined Patent Publication No. 46-17128 US Pat. No. 5,359,011 JP 2003-238615 A JP 2001-11116 A JP 2004-99669 A

  Provided is a method for producing a chlorinated vinyl chloride resin that achieves efficient hydrochloric acid removal in order to reduce the load of hydrochloric acid removal of equipment by by-product hydrochloric acid of chlorination reaction.

  In view of the above problems, the present inventors have completed the present invention as a result of intensive studies.

  The method for producing a chlorinated vinyl chloride resin of the present invention comprises a chlorinated vinyl chloride resin slurry obtained by chlorinating a vinyl chloride resin or a copolymer of vinyl chloride and another copolymerizable monomer. Hypochlorite is added to the chlorinated vinyl chloride resin slurry or water-containing resin during or after the step of separating the aqueous solution of hydrochloric acid by-produced.

  According to the present invention, an aqueous solution of hydrochloric acid by-produced from a chlorinated vinyl chloride resin slurry obtained by chlorinating a vinyl chloride resin or a copolymer of vinyl chloride and another copolymerizable monomer is obtained. By adding hypochlorite to the chlorinated vinyl chloride resin slurry or water-containing resin during or after the separation step, hydrochloric acid by-produced by the chlorination reaction can be efficiently removed. This reduces the hydrochloric acid concentration in the chlorinated vinyl chloride resin or chlorinated vinyl chloride copolymer resin before the drying process, reduces the load of removing hydrochloric acid in the subsequent drying process, and reduces problems such as corrosion of the dryer. it can.

  The method for producing a chlorinated vinyl chloride resin of the present invention is produced as a by-product from a chlorinated resin slurry obtained by chlorinating a vinyl chloride resin or a copolymer of vinyl chloride and another copolymerizable monomer. Hypochlorite is added to the chlorinated vinyl chloride resin slurry or water-containing resin during or after the step of separating the aqueous hydrochloric acid solution.

  In the present invention, it is preferable that the pH of the water-containing resin or the redispersed slurry at 25 ° C. is adjusted to 3 to 8 by adding hypochlorite.

  Moreover, it is preferable that the water-containing resin or redispersion slurry temperature when adding hypochlorite is 40-90 degreeC.

  Moreover, it is preferable to add a basic substance before adding hypochlorite.

  Moreover, after filtering the water-containing resin or slurry treated with hypochlorite, separating the resin powder particles using a centrifugal separation or sedimentation separation method, the resin particles can be obtained by using a dryer in the drying process. It is preferable to obtain a body.

  The vinyl chloride resin that is the raw material of the chlorinated vinyl chloride resin is obtained as a slurry of water or as a dry powder resin. If it is in the form of a slurry, it is dried as it is or after removing impurities in the water by filtration etc. If it is a powder resin, it is slurried again with water and supplied to the chlorination step.

  The chlorination process is a process for producing a heat-resistant resin by adding chlorine to a slurryed vinyl chloride resin, which is irradiated with light (ultraviolet rays) while supplying chlorine gas into the slurry. A photochlorination method in which chlorine is reacted and a thermal chlorination method in which chlorine is reacted using heat are industrially implemented.

  Resin chlorinated by the chlorination process, that is, the slurry of the chlorinated vinyl chloride resin, removes most of the water and by-product hydrochloric acid in the subsequent filtration or centrifugation process, and is further sent to the drying process to be finally obtained. The method of obtaining the product as a powder is taken.

  The vinyl chloride resin in the present invention is a vinyl chloride homopolymer or a vinyl chloride and other copolymerizable monomer (for example, ethylene, propylene, vinyl acetate, allyl chloride, allyl glycidyl ether, acrylate ester). , Vinyl ether, etc.). Dispersants such as partially saponified polyvinyl alcohol, methyl cellulose, hydroxypropyl methyl cellulose, polyethylene oxide, and lauroyl peroxide, di-2-ethylhexyl peroxyneodecanoate, t-butylperoxyneodecanoate , Α, α′-azobis-2,4-dimethylvaleronitrile and other oil-soluble polymerization initiators are used for polymerization by suspension polymerization. The ratio of the vinyl chloride and other copolymerizable monomer is 50% by weight / 50% by weight to 99.9% by weight / 0.1% by weight, which expresses the heat resistance performance of the chlorinated vinyl chloride resin. Therefore, it is preferable.

  Usually, a polyvinyl chloride single resin having a viscosity average polymerization degree of 350 to 1250 is preferably used. Use of a material having a viscosity average degree of polymerization in the range of 350 to 1250 is preferable because both the heat resistance performance of the chlorinated vinyl chloride resin and the molding process can be achieved.

  A chlorinated vinyl chloride resin refers to a product obtained by adding chlorine to a vinyl chloride resin by a chlorination step. It is desirable to obtain a chlorinated vinyl chloride resin by chlorinating the vinyl chloride resin in an aqueous suspension at a resin concentration of 10 to 40% by weight. The range of 10 to 40% by weight is preferable from the viewpoints of productivity, viscosity stability of the aqueous suspension, and uniform mixing during stirring. If it is the range of 20 to 35 weight%, it is still more preferable from a viewpoint of uniform mixing of productivity and stirring. When chlorinating at a resin concentration of less than 10% by weight, it is necessary to balance the production cost, but the hydrochloric acid concentration can be further reduced, and when the hydrochloric acid concentration needs to be reduced as much as possible, It can be an effective method. There are no particular restrictions on the chlorination reaction, and a photochlorination method of irradiating ultraviolet rays with a mercury lamp, a method of chlorination using a catalyst, a method of applying heat (thermal chlorination method), or a combination thereof is possible. is there. A mercury lamp is a light source that utilizes light radiation generated by arc discharge in mercury vapor in a glass tube, a low-pressure mercury lamp with a mercury pressure of about 1 to 10 kPa during lighting or a high pressure with a mercury pressure of about 100 to 1000 kPa during lighting. There are mercury lamps or ultra-high pressure mercury lamps whose mercury pressure during lighting exceeds 1000 kPa, but any mercury lamp may be used as long as it has ultraviolet radiation. In the present invention, at least one method selected from a photochlorination method, a thermal chlorination method, and a chlorination method using a catalyst can be employed.

  For example, a chlorination reaction apparatus that irradiates ultraviolet rays with a mercury lamp is not particularly limited. For example, as shown in FIG. 1, a stirrer 5, a cooling jacket 2, a chlorine supply apparatus 3, and a mercury lamp 4 are provided. What is necessary is just to be attached to the reaction apparatus 1. FIG. Since a large amount of hydrochloric acid is produced as a by-product in the reactor, a tank coated with an acid-resistant metal or a glass lining tank is preferably used.

  In the present invention, chlorine supplied to the aqueous medium may be gaseous or liquid, but from the viewpoint of easy handling, a method of supplying gaseous chlorine gas into the aqueous medium is preferable. .

  The aqueous suspension resin slurry thus obtained is referred to as a chlorinated vinyl chloride resin slurry.

  In the present invention, “separation” means an operation of separating the water-containing resin and the by-product hydrochloric acid aqueous solution using a separation device. The resin obtained by the separator is called “hydrous resin”, and the by-product hydrochloric acid produced by adding chlorine to the vinyl chloride resin in the chlorination process is dissolved in the chlorinated vinyl chloride resin slurry as an aqueous solution. The aqueous solution in the state is called “by-product hydrochloric acid aqueous solution”. As a pretreatment of the resin before adding hypochlorite, an apparatus for separating the water-containing resin and the by-product hydrochloric acid aqueous solution is required to enhance the effect of hypochlorite. This includes various filters, centrifuges, etc., and it may be further provided with a function of injecting water into the separation device to increase the hydrochloric acid washing efficiency, or hypochlorous acid added in the present invention. Salt may be fed into the apparatus. Although it does not specifically limit as a filter, A pressure filter, a vacuum filter, etc. can be used, In order to improve the water | moisture-content exclusion effect by filtration, you may use a filter press. The centrifuge is not particularly limited as long as it has a moisture exclusion effect by centrifugal force, but a vertical centrifuge having a vertical rotation axis and a horizontal centrifuge having a horizontal rotation axis can be used. . The water content of the water-containing resin after water separation is not particularly limited, but it is effective in terms of efficient hydrochloric acid removal to be 10 to 50% by weight with respect to the water-containing resin. Furthermore, if it is 10 to 35 weight%, the hydrochloric acid removal efficiency may further increase. As hypochlorite used in the present invention, sodium hypochlorite, potassium hypochlorite, calcium hypochlorite, etc. are used. From the viewpoint of ease of handling, production cost, etc. Sodium chlorate is preferably used.

  The method for adding hypochlorite is not particularly limited, but a method of supplying a water-containing resin and an aqueous solution of hydrochloric acid by-produced with a metering pump into a device for separating the aqueous solution of hydrochloric acid by-produced, and providing a stirring tank after the separation device , A method of mixing the hydrated resin and hypochlorite therein, and when mixing the hydrated resin and hypochlorite in the stirring tank, water is added and stirred to redisperse the resin in water However, slurrying is preferred from the viewpoint of uniformity of mixing. In addition, water may be added and slurried again before adding hypochlorite after separation. The amount of water used in the case of slurrying is preferably 100 parts by weight or more and 10,000 parts by weight or less with respect to 100 parts by weight of the resin component of the water-containing resin. From the viewpoint, 100 parts by weight or more and 1,000 parts by weight or less are still more preferable. Furthermore, in order to stabilize the pH during the treatment, a method of adding a hypochlorite aqueous solution intermittently or continuously may be used.

  The effective chlorine concentration of the hypochlorite to be added is not particularly limited, but it is preferably 1% by weight or more and 16% by weight or less from the viewpoint of production cost, and 5% by weight or more and 16% by weight or less is the production cost and ease of handling. It is still preferable from the viewpoint. Here, the effective chlorine concentration means the weight of chlorine that acts as a hypochlorite with the chlorine content in the solution. For example, an aqueous solution of sodium hypochlorite having an effective chlorine concentration of 13% by weight means that the chlorine atom in sodium hypochlorite contains 13% by weight of the aqueous solution, in other words, 27.3% by weight of sodium hypochlorite. % Sodium hypochlorite aqueous solution. As a method for measuring the effective chlorine concentration, the iodometric titration method is the most common, and for example, it can be quantified by the following method. The test water containing available chlorine is made weakly acidic and potassium iodide is added to release iodine. The iodine is titrated with sodium thiosulfate solution, which is a reducing agent, using starch as an indicator, and the effective chlorine concentration in the test water is determined from the titration amount. The amount of hypochlorite to be added is not particularly limited, but is preferably 0.002 times or more and 0.1 times or less with respect to the CPVC resin in order to make the hydrochloric acid concentration in the water-containing resin before drying 100 ppm, 0 It is still preferable from the viewpoint of production cost to be 0.002 times or more and 0.05 times or less. Depending on the amount of hypochlorite to be added, there may be a case where there is a concern about the quantitativeness in the case of supplying with a pump or the like. In some cases, a method of preparing a dilute hypochlorite solution (1% by weight or less) and then mixing with a water-containing resin may be used.

  The pH in the present invention indicates a value measured by a Japanese Industrial Standard pH measurement method (JIS Z 8802 1984). The measured value of pH is obtained by placing a collected sample in a container such as a beaker and keeping it at 25 ° C. The value measured after confirming that the sample temperature reached 25 ° C. in a water bath or the like. The pH to be adjusted by adding hypochlorite is not particularly limited as long as the object of the present invention can be achieved, but is preferably 1 to 12 from the viewpoint of the material and production cost of the equipment to be used, and safety. From the viewpoint of reactivity with hypochlorite, 3 to 11 is more preferable.

  Various basic substances can be used to adjust the pH before adding hypochlorite. Examples of basic substances include, but are not limited to, hydroxides such as caustic soda, potassium hydroxide, and calcium hydroxide, alkaline inorganic salts such as sodium carbonate, potassium carbonate, sodium silicate, and potassium silicate, and ammonia. . Of these, caustic soda is preferable from the viewpoint of cost. These may be used as they are or as an aqueous solution.

  The pH of the chlorinated vinyl chloride resin slurry or water-containing resin produced by the production method of the present invention is preferably 3 to 11 as measured at 25 ° C., more preferably 3 to 8, and 3 to 8. 7 is particularly preferred.

  If the pH of the chlorinated vinyl chloride resin slurry or water-containing resin to be generated is in the range of 3 to 8, the cost of production equipment can be reduced, and the amount of hypochlorite to be used can be kept low.

  In addition, if the slurry is a slurry, the pH of the slurry can be measured by immersing the measurement pH electrode directly in the slurry, and if it is a hydrous resin, the pH of the hydrous resin is a small amount of pure water added to the hydrous resin. Then, the pH electrode was immersed and the value estimated by the following formula (1) from the value was used.

(PH of water-containing resin) = (measured pH) + log (V1 / (V1 + V2)) (1)
V1 = water content in water-containing resin (ml)
V2 = Moisture added (ml)

  The temperature at which hypochlorite is added refers to the temperature at which hypochlorite is added to the hydrous resin or chlorinated vinyl chloride resin slurry and the temperature during hypochlorite treatment. The temperature is not particularly limited, but is preferably 0 to 95 ° C. because it is an operation containing water. From the viewpoint of production costs such as the time required for the reaction between hydrochloric acid and hypochlorite, decomposition of hypochlorite, etc. 40-95 degreeC is more preferable and 60-95 degreeC is still more preferable.

  Examples of the apparatus for separating the water-containing resin and water of the chlorinated vinyl chloride resin after the hypochlorite treatment before drying include various filters and centrifuges. If the separation device is provided with a function of washing capability, the dehydrated resin can be further subjected to water washing and subsequent dehydration, so that efficient washing can be performed. Although it does not specifically limit as a filter, A pressure filter, a vacuum filter, etc. can be used, In order to improve the water | moisture-content exclusion effect by filtration, you may use a filter press. The centrifuge is not particularly limited as long as it has a moisture exclusion effect by centrifugal force. Specifically, a vertical centrifuge having a vertical rotation axis and a horizontal centrifuge having a horizontal rotation axis can be used. Although not particularly limited, it is preferable to use a centrifuge from the viewpoint of ease of production such as ease of taking out the water-containing resin. After separation, the slurry may be re-slurried with water, and the hypochlorite, other generated salts, and residual hydrochloric acid may be washed, and then the water-containing resin and water may be separated again using a separation device. The water content of the water-containing resin after this operation is not particularly limited, but it is effective in terms of energy efficiency in drying to be 10 to 50% by weight with respect to the water-containing resin. Furthermore, if it is 10 to 35 weight%, the energy efficiency in drying may further increase.

  Various dryers can be used for drying the moisture in the water-containing resin. For example, it is possible to obtain a product granule by using a grooved agitation dryer in the conduction heat transfer system and a fluidized dryer in the hot air heat reception system. Further, an extruder may be provided after the dryer to pelletize, or an apparatus for providing a degassing function to the extruder and pelletizing at the same time as evaporation of water may be used. Although it does not specifically limit as a drying system, It is preferable to use a fluid dryer from a viewpoint of production cost.

  Although an Example is shown below and specific embodiment of this invention is described in detail, these do not limit this invention at all.

  In the examples, the hydrochloric acid concentration is the concentration relative to the solid content of the resin. At 25 ° C., 1.0 g of the resin in the target sample was dissolved in 40 ml of tetrahydrofuran to extract hydrochloric acid in the resin, and then methanol: water = Using a sample in which 30 ml of a mixed solution of 5: 1 (volume ratio) was added to reprecipitate the resin component, titration was performed using a 0.01N sodium hydroxide aqueous solution, and the pH was calculated from the titration value at 7.0. Quantified by subtracting the titration amount when no sample is added (blank).

    In the examples, the pH of the slurry was measured by confirming that the sample temperature was 25 ° C in a water bath kept at 25 ° C by collecting a part of the slurry sample and putting it in a container such as a beaker. For measurement, D-51S manufactured by Horiba, Ltd. was used.

(Evaluation method of initial colorability)
In the examples, the initial colorability was evaluated by the following method. With respect to 100 parts by weight of the obtained CPVC dry powder, 10 parts by weight of impact resistance enhancer (trade name “Kane Ace B22” manufactured by Kaneka Corporation), 3 parts by weight of dibutyltin mercapto stabilizer, 1.2 parts by weight of paraffin wax Was blended with a roll at 175 ° C. for 3 minutes to prepare a sheet having a thickness of 0.6 mm. The sheets were overlapped and pressed at 180 ° C. for 10 minutes to obtain a pressed plate having a thickness of 3 mm. This press plate was subjected to initial colorability.

The initial colorability was determined by visually observing the press plate as follows.
A: Light yellow that is almost colorless B: Light yellow C: Yellow

(Example 1)
A chlorination reactor having an internal volume of 50 L, equipped with a stirring blade, a cooling jacket, and an ultraviolet irradiation lamp, was charged with 15 kg of vinyl chloride resin with a polymerization degree of 670 and 35 kg of ion-exchanged water. After performing nitrogen substitution for a predetermined time, chlorine gas was blown into the system, and ultraviolet rays were irradiated to start the chlorination reaction. The temperature and pressure in the reactor were controlled at 50 ° C. and 0.02 MPa, respectively. The hydrochloric acid concentration was measured over time, and when the degree of chlorination reached 64% by weight from a calibration curve prepared in advance, the ultraviolet irradiation was stopped and the chlorination reaction was terminated to obtain a chlorinated vinyl chloride resin slurry.

  1.5 L of the obtained chlorinated vinyl chloride resin slurry was filtered with a Buchner funnel to obtain a water-containing resin. Filtration was carried out by vacuum filtration at a pressure of about 300 mmHg for 1 minute at 25 ° C. using a suction filter bottle and a diaphragm vacuum pump. The water content of the obtained water-containing resin was about 25% by weight with respect to the water-containing resin. This was put into a glass stirring tank having an internal volume of 2 L, and water was added to make the slurry volume 1.5 L. This was put in a constant temperature water bath and the internal temperature was set to 80 ° C., and then an aqueous sodium hypochlorite solution (effective chlorine concentration 13 wt%) was added to adjust the pH to 6.5. Thereafter, an aqueous sodium hypochlorite solution was dropped while monitoring the pH to be 6.5, and after 60 minutes from the start of the addition of sodium hypochlorite, it was filtered again with a Buchner funnel to obtain a water-containing resin. Filtration was carried out by vacuum filtration at a pressure of about 300 mmHg for 1 minute at 25 ° C. using a suction filter bottle and a diaphragm vacuum pump. The water content of the obtained water-containing resin was about 25% by weight with respect to the water-containing resin.

  At this time, the hydrochloric acid concentration in the water-containing resin 1 hour after the addition of sodium hypochlorite was 70 ppm. The results are shown in Table 1.

  When the obtained water-containing resin was dried with a box-type dryer having a hot air temperature of 120 ° C. until the water content became 0.1% by weight or less, the hydrochloric acid concentration in the obtained dry powder resin was 70 ppm, It was confirmed that hydrochloric acid was not volatilized.

  Furthermore, this dry powder resin was evaluated based on the above-described initial colorability evaluation method. The initial colorability was A (light yellow, almost colorless).

(Example 2)
The same operation as in Example 1 was performed except that the internal temperature during the treatment with sodium hypochlorite was set to 70 ° C.

  At this time, the hydrochloric acid concentration in the water-containing resin 1 hour after the addition of sodium hypochlorite was 70 ppm. The results are also shown in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Example 1, the concentration of hydrochloric acid in the obtained dry powder was similarly 70 ppm, and it was confirmed that hydrochloric acid was not volatilized during drying.

(Example 3)
The same operation as in Example 1 was performed except that the internal temperature during the treatment with sodium hypochlorite was set to 65 ° C.

  At this time, the hydrochloric acid concentration in the water-containing resin 1 hour after the addition of sodium hypochlorite was 70 ppm. The results are also shown in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Example 1, the concentration of hydrochloric acid in the obtained dry powder was similarly 70 ppm, and it was confirmed that hydrochloric acid was not volatilized during drying.

Example 4
The same operation as in Example 1 was conducted except that the pH during the treatment with sodium hypochlorite was 4.0.

  At this time, the hydrochloric acid concentration in the water-containing resin 1 hour after the addition of sodium hypochlorite was 70 ppm. The results are also shown in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Example 1, the concentration of hydrochloric acid in the obtained dry powder was similarly 70 ppm, and it was confirmed that hydrochloric acid was not volatilized during drying.

(Example 5)
This was carried out in the same manner as in Example 1, except that the pH was adjusted to 2.0 with an aqueous sodium hydroxide solution, sodium hypochlorite was added, and the pH during the sodium hypochlorite treatment was adjusted to 6.5.

  At this time, the hydrochloric acid concentration in the water-containing resin 1 hour after the addition of sodium hypochlorite was 70 ppm. The results are also shown in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Example 1, the concentration of hydrochloric acid in the obtained dry powder was similarly 70 ppm, and it was confirmed that hydrochloric acid was not volatilized during drying.

(Example 6)
In Example 1, except that 1.5 L of chlorinated vinyl chloride resin slurry was filtered under reduced pressure for 1 minute, and 250 parts by weight of ion-exchanged water was further added to the water-containing resin as a resin cleaning solution, followed by filtration again. The same operation as 1 was performed.

  The water content of the obtained water-containing resin was about 25% by weight with respect to the water-containing resin.

  At this time, the hydrochloric acid concentration in the water-containing resin 1 hour after the addition of sodium hypochlorite was 70 ppm. The results are summarized in Table 1.

  When the obtained water-containing resin was dried with a box-type dryer having a hot air temperature of 120 ° C. until the water content became 0.1% by weight or less, the resulting hydrochloric acid concentration was 70 ppm, and hydrochloric acid was volatilized during drying. Not confirmed.

  Furthermore, this dry powder resin was evaluated based on the evaluation method of the initial colorability. The initial colorability was A (light yellow, almost colorless).

(Example 7)
The same procedure as in Example 1 was performed except that the treating agent was potassium hypochlorite.

  At this time, the hydrochloric acid concentration in the water-containing resin 1 hour after the addition of potassium hypochlorite was 70 ppm. The results are summarized in Table 1.

(Example 8)
The same procedure as in Example 1 was performed except that the treatment agent was calcium hypochlorite.

  At this time, the hydrochloric acid concentration in the water-containing resin 1 hour after the addition of potassium hypochlorite was 70 ppm. The results are summarized in Table 1.

Example 9
The same operation as in Example 1 was performed except that the pH during the treatment with sodium hypochlorite was set to 3.0.

  At this time, the hydrochloric acid concentration in the water-containing resin 1 hour after the addition of sodium hypochlorite was 70 ppm. The results are also shown in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Example 1, the concentration of hydrochloric acid in the obtained dry powder was similarly 70 ppm, and it was confirmed that hydrochloric acid was not volatilized during drying.

(Example 10)
The same operation as in Example 1 was conducted except that the pH during the treatment with sodium hypochlorite was 8.0.

  At this time, the hydrochloric acid concentration in the water-containing resin 1 hour after the addition of sodium hypochlorite was 90 ppm. The results are also shown in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Example 1, the concentration of hydrochloric acid in the obtained dry powder was similarly 70 ppm, and it was confirmed that 20 ppm of hydrochloric acid was volatilized during drying.

(Comparative Example 1)
When the chlorinated vinyl chloride resin slurry obtained in Example 1 was filtered with a Buchner funnel, 10 times the amount of pure water was added to the water-containing resin after filtration and filtered again. Filtration was performed by vacuum filtration using a suction filter bottle and a diaphragm vacuum pump at a pressure of about 300 mmHg for 1 minute in an atmosphere of 25 ° C. The water content of the obtained water-containing resin was about 25% by weight with respect to the water-containing resin. At this time, the concentration of hydrochloric acid contained in the water-containing resin was 800 ppm. This was put into a glass stirring tank having an internal volume of 2 L, and pure water was added to make the slurry volume 1.5 L. This was placed in a constant temperature water bath and stirred at an internal temperature of 80 ° C.

  At this time, the hydrochloric acid concentration in the water-containing resin after 1 hour was 460 ppm. Further, it was 220 ppm even after 3 hours. The results are also shown in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Example 1, it was confirmed that the hydrochloric acid concentration in the obtained dry powder was 70 ppm, and 150 ppm of hydrochloric acid was volatilized during the drying.

  Furthermore, this dry powder resin was evaluated based on the evaluation method of the initial colorability. The initial colorability was B (light yellow).

  Moreover, the graph of the hydrochloric acid density | concentration time-dependent change of resin of the comparative example 1 and the said Examples 1 and 4 is shown in FIG. It can be seen that the hydrochloric acid concentrations of Examples 1 and 4 of the present invention are greatly reduced in a short time as compared with Comparative Example 1.

(Comparative Example 2)
The same operation as in Comparative Example 1 was performed except that the internal temperature was 110 ° C.

  At this time, the hydrochloric acid concentration in the water-containing resin after 1 hour was 350 ppm. Further, it was 220 ppm even after 3 hours. The results are also shown in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Example 1, it was confirmed that the hydrochloric acid concentration in the obtained dry powder was 70 ppm, and 150 ppm of hydrochloric acid was volatilized during the drying.

(Comparative Example 3)
The same procedure as in Example 1 was performed except that a sodium hydroxide aqueous solution was used instead of sodium hypochlorite.

  At this time, the hydrochloric acid concentration in the water-containing resin 1 hour after addition of the aqueous sodium hydroxide solution was 400 ppm. Further, it was 190 ppm even when extended to 3 hours later. The results are also shown in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Example 1, the hydrochloric acid concentration in the obtained dry powder was 70 ppm, and it was confirmed that 120 ppm of hydrochloric acid was volatilized during drying.

  Furthermore, this dry powder resin was evaluated based on the evaluation method of the initial colorability. The initial colorability was B (light yellow).

(Comparative Example 4)
The same procedure as in Example 1 was performed except that an aqueous sodium carbonate solution was used instead of sodium hypochlorite.

  At this time, the hydrochloric acid concentration in the water-containing resin 1 hour after the addition of the sodium carbonate aqueous solution was 450 ppm. Even after extending to 3 hours later, it was 210 ppm. The results are also shown in Table 1.

  The obtained water-containing resin was dried in the same manner as in Example 1. As a result, the hydrochloric acid concentration in the obtained dry powder was 70 ppm, and it was confirmed that 140 ppm of hydrochloric acid was volatilized during drying.

  Furthermore, this dry powder resin was evaluated based on the evaluation method of the initial colorability. The initial colorability was B (light yellow).

(Comparative Example 5)
The same procedure as in Example 1 was performed except that an aqueous sodium citrate solution was used instead of sodium hypochlorite.

  At this time, the hydrochloric acid concentration in the water-containing resin 1 hour after the addition of the aqueous sodium citrate solution was 500 ppm. Further, it was 220 ppm even after 3 hours. The results are also shown in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Example 1, the hydrochloric acid concentration in the obtained dry powder was 70 ppm, and it was confirmed that 150 ppm of hydrochloric acid was volatilized during drying.

(Comparative Example 6)
In Comparative Example 1, the chlorinated vinyl chloride resin slurry was filtered under reduced pressure for 1 minute, and then filtered again after adding 250 parts by weight of ion-exchanged water to the water-containing resin as a resin cleaning solution. Was performed.

  At this time, the concentration of hydrochloric acid contained in the water-containing resin was 800 ppm. This was put into a 2 L glass stirring tank, and pure water was added to make the slurry volume 1.5 L. This was placed in a constant temperature water bath and stirred at an internal temperature of 80 ° C. The hydrochloric acid concentration in the water-containing resin after 1 hour was 460 ppm. Further, it was 220 ppm even after 3 hours. The results are summarized in Table 1.

  Furthermore, this dry powder resin was evaluated based on the evaluation method of the initial colorability. The initial colorability was B (light yellow).

(Comparative Example 7)
In Comparative Example 3, the chlorinated vinyl chloride resin slurry was filtered under reduced pressure for 1 minute, and then filtered again after adding 250 parts by weight of ion-exchanged water to the water-containing resin as a resin cleaning solution. Was performed.

  At this time, the hydrochloric acid concentration of the water-containing resin 1 hour after the addition of the aqueous sodium hydroxide solution was 400 ppm. Further, it was 190 ppm even when extended to 3 hours later. The results are summarized in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Example 1, the hydrochloric acid concentration in the obtained dry powder was 70 ppm, and it was confirmed that 150 ppm of hydrochloric acid was volatilized during drying.

  Furthermore, this dry powder resin was evaluated based on the evaluation method of the initial colorability. The initial colorability was B (light yellow).

(Comparative Example 8)
Comparative Example 4 was the same as Comparative Example 4 except that the chlorinated vinyl chloride resin slurry was filtered under reduced pressure for 1 minute, and 250 parts by weight of ion-exchanged water was further added to the water-containing resin as a resin cleaning solution and filtered again. Was performed.

  At this time, the hydrochloric acid concentration of the water-containing resin 1 hour after addition of the aqueous sodium carbonate solution was 450 ppm. Even after extending to 3 hours later, it was 210 ppm. The results are summarized in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Comparative Example 4, the hydrochloric acid concentration in the obtained dry powder was 70 ppm, and it was confirmed that 140 ppm of hydrochloric acid was volatilized during drying.

  Furthermore, this dry powder resin was evaluated based on the evaluation method of the initial colorability. The initial colorability was B (light yellow).

(Comparative Example 9)
Comparative Example 9 is an additional test of the example described in Patent Document 4, and is compared with the example of the present invention.

  Into a 50-liter chlorination reactor equipped with a stirring blade and cooling jacket, 5 kg of vinyl chloride resin with a polymerization degree of 670, 12 kg of ion-exchanged water, and 21.8 kg of sodium hypochlorite aqueous solution (effective chlorine concentration 13%) The reactor was vacuum degassed and purged with nitrogen for a predetermined time while stirring and stirring, and then 8.3 kg of a 35 wt% aqueous hydrochloric acid solution was added to start the chlorination reaction. The temperature in the reactor was controlled at 60 ° C. After 6 hours, the chlorination reaction was terminated to obtain a chlorinated vinyl chloride resin slurry. At this time, sodium hypochlorite did not remain in the resin slurry.

  1.5 L of the obtained chlorinated vinyl chloride resin slurry was filtered with a Buchner funnel, and after filtration, 10 times the amount of pure water was added to the water-containing resin and filtered again. Filtration was carried out by vacuum filtration at a pressure of about 300 mmHg for 1 minute at 25 ° C. using a suction filter bottle and a diaphragm vacuum pump. The water content of the obtained water-containing resin was about 25% by weight with respect to the water-containing resin. At this time, the concentration of hydrochloric acid contained in the water-containing resin was 800 ppm. This was put into a glass stirring tank having an internal volume of 2 L, and pure water was added to make the slurry volume 1.5 L. This was placed in a constant temperature water bath and stirred at an internal temperature of 80 ° C.

  At this time, the hydrochloric acid concentration in the water-containing resin after 1 hour was 460 ppm. Further, it was 220 ppm even after 3 hours. The results are also shown in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Example 1, it was confirmed that the hydrochloric acid concentration in the obtained dry powder was 70 ppm, and 150 ppm of hydrochloric acid was volatilized during the drying.

(Comparative Example 10)
Comparative Example 10 is an additional test of the example described in Patent Document 5, and is compared with the example of the present invention.

  A chlorination reactor with an internal volume of 50 L, equipped with a stirring blade, a cooling jacket, and an ultraviolet irradiation lamp, 7.5 kg of vinyl chloride resin with a polymerization degree of 670, 42.5 kg of ion-exchanged water, an aqueous sodium hypochlorite solution (effective chlorine (Concentration 13% by weight) 2.1 kg (0.58 kg of sodium hypochlorite) was charged, vacuum deaeration and nitrogen replacement were carried out for a predetermined time while stirring, and then chlorine gas was blown into the system. Was initiated to initiate the chlorination reaction. The temperature and pressure in the reactor were controlled at 50 ° C. and 0.02 MPa, respectively. The hydrochloric acid concentration was measured over time, and when the degree of chlorination reached 64% by weight from a calibration curve prepared in advance, the ultraviolet irradiation was stopped and the chlorination reaction was terminated to obtain a chlorinated vinyl chloride resin slurry. At this time, sodium hypochlorite did not remain in the resin slurry.

  1.5 L of the obtained chlorinated vinyl chloride resin slurry was filtered with a Buchner funnel, and after filtration, 10 times the amount of pure water was added to the water-containing resin and filtered again. Filtration was carried out by vacuum filtration at a pressure of about 300 mmHg for 1 minute at 25 ° C. using a suction filter bottle and a diaphragm vacuum pump. The water content of the obtained water-containing resin was about 25% by weight with respect to the water-containing resin. At this time, the concentration of hydrochloric acid contained in the water-containing resin was 800 ppm. This was put into a glass stirring tank having an internal volume of 2 L, and pure water was added to make the slurry volume 1.5 L. This was placed in a constant temperature water bath and stirred at an internal temperature of 80 ° C.

  At this time, the hydrochloric acid concentration in the water-containing resin after 1 hour was 460 ppm. Further, it was 220 ppm even after 3 hours. The results are also shown in Table 1.

  When the obtained water-containing resin was dried in the same manner as in Example 1, it was confirmed that the hydrochloric acid concentration in the obtained dry powder was 70 ppm, and 150 ppm of hydrochloric acid was volatilized during the drying.

  As described above, it can be confirmed that the concentration of hydrochloric acid in the CPVC resin before drying treatment obtained in Examples 1 to 10, that is, the water-containing resin, is low, thereby reducing the load of removing hydrochloric acid in the subsequent drying treatment. I was able to. Moreover, the initial colorability was also improved.

  Moreover, the aspect of Comparative Examples 1-10 had a residual chlorine concentration of 70 ppm in the resin after drying. The reason is not clear, but unlike the embodiments 1 to 10 of the present invention, the initial coloring was inferior.

FIG. 1 is an explanatory view of a chlorination reaction apparatus in one embodiment of the present invention. FIG. 2 is an explanatory diagram of changes in hydrochloric acid concentration in the resin over time in Examples 1 and 4 and Comparative Example 1 of the present invention.

Explanation of symbols

1 Reactor 2 Cooling Jacket 3 Chlorine Supply Device 4 Mercury Lamp 5 Stirrer

Claims (13)

  During or during the process of separating an aqueous hydrochloric acid solution by-produced from a chlorinated vinyl chloride resin slurry obtained by chlorinating a vinyl chloride resin or a copolymer of vinyl chloride and another copolymerizable monomer A method for producing a chlorinated vinyl chloride resin, in which hypochlorite is added to a chlorinated vinyl chloride resin slurry or a water-containing resin later.   The method for producing a chlorinated vinyl chloride resin according to claim 1, wherein the pH of the chlorinated vinyl chloride resin slurry or the hydrated resin is adjusted to 3 to 8 by adding the hypochlorite.   The chlorinated vinyl chloride according to claim 2, wherein the pH during treatment is stabilized by intermittently or continuously adding an aqueous solution of hypochlorite to the chlorinated vinyl chloride resin slurry or water-containing resin. Method for production of resin.   The method for producing a chlorinated vinyl chloride resin according to any one of claims 1 to 3, wherein a temperature of the water-containing resin or the redispersion slurry when adding the hypochlorite is 0 to 95 ° C.   The chlorinated chloride according to any one of claims 1 to 4, wherein the hypochlorite is at least one selected from sodium hypochlorite, potassium hypochlorite, and calcium hypochlorite. Manufacturing method of vinyl resin.   The chlorination is a photochlorination method in which chlorine is reacted by irradiating light while supplying chlorine gas to the slurry when chlorine is added to the slurry vinyl chloride resin, and chlorine is reacted using heat. The method for producing a chlorinated vinyl chloride resin according to any one of claims 1 to 5, which is carried out by at least one method selected from a thermal chlorination method to be performed and a chlorination method using a catalyst.   The method for producing a chlorinated vinyl chloride resin according to any one of claims 1 to 6, wherein the water content of the water-containing resin before chlorination is in the range of 10 to 50 wt% with respect to the water-containing resin.   The chlorine according to any one of claims 1 to 7, wherein an effective chlorine concentration of hypochlorite in the chlorinated vinyl chloride resin slurry or water-containing resin is in a range of 1 wt% to 16 wt%. Of manufacturing a vinyl chloride resin.   The method for producing a chlorinated vinyl chloride resin according to any one of claims 1 to 8, wherein the pH is adjusted by adding a basic substance before adding the hypochlorite.   The chlorinated vinyl chloride according to claim 9, wherein the basic substance is at least one selected from caustic soda, potassium hydroxide, calcium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, potassium silicate, and ammonia. Method for production of resin.   The water-containing resin or slurry treated with the hypochlorite is further separated into resin particles by filtration, centrifugation or sedimentation separation, and then the resin powder is obtained by using a dryer in the drying step. The manufacturing method of the chlorinated vinyl chloride-type resin of any one of Claims 1-10 which obtains a granule.   The monomer copolymerizable with vinyl chloride is at least one selected from ethylene, propylene, vinyl acetate, allyl chloride, allyl glycidyl ether, acrylic acid ester, and vinyl ether. A method for producing a chlorinated vinyl chloride resin according to claim 1.   The ratio of the vinyl chloride to the other copolymerizable monomer is vinyl chloride / other copolymerizable monomer = 50 wt% / 50 wt% to 99.9 wt% / 0.1 wt%. It is a range, The manufacturing method of the chlorinated vinyl chloride-type resin of any one of Claims 1-12.

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