JP2007169349A - Method for production of chlorinated vinyl chloride resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing chlorinated vinyl chloride resin attaining an effective elimination of hydrogen chloride, reducing the load to the facilities in removing the by-product hydrogen chloride in the chlorinating reaction relating to a method for producing the chlorinated vinyl chloride resin obtained by chlorination of a vinyl chloride resin. <P>SOLUTION: The invention relates to the method for production of chlorinated vinyl chloride resin comprising addition of a solvent having solubility parameter of 16-20 (MPa)<SP>1/2</SP>and ≤1% of saturated solubility of water, to a water slurry of the chlorinated vinyl chloride resin obtained by chlorinating the vinyl chloride resin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

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

A chlorinated vinyl chloride resin (hereinafter referred to as “CPVC” for simplicity) 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, it is a method in which a vinyl chloride resin (hereinafter referred to as “PVC” for simplicity) 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 a 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 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 concentration of hydrochloric acid in the slurry after the chlorination reaction becomes 5 to 12%, for example, and equipment corrosion of reactors and dryers becomes remarkable. Therefore, equipment is coated with expensive metals to prevent equipment corrosion. Treatment was necessary. Moreover, since the hydrochloric acid in the slurry wastewater after the chlorination reaction is about 20,000 ppm with respect to the resin after centrifugation or filtration, there is an industrial problem that a large amount of water is required for washing. .

In order to improve this, there has been proposed a method of adding a hypochlorite metal salt to a slurry in which PVC is suspended in an aqueous medium and adding a protonic acid thereto to chlorinate (Patent Document 2). . Certainly, according to this method, the amount of acid contained in the slurry after the reaction is reduced. However, in this method, since a protic acid is introduced from outside the system, the chlorination reaction inside the PVC hardly occurs, an unstable vinylidene structure (—CCl ₂ —) is generated, or a metal hypochlorite is reacted after the reaction. There are practical problems such as residual coloring in resin and deterioration of initial coloration and thermal stability. Also, hypochlorite is added to the slurry in which PVC is suspended in an aqueous medium, and hydrochloric acid and by-chlorite produced as a by-product in the chlorination reaction are reacted while blowing chlorine gas to regenerate it as chlorine gas. Thus, a method of suppressing the total amount of hydrochloric acid produced has also been proposed (Patent Document 3). According to this method, chlorination reaction can be performed while suppressing the amount of hydrochloric acid produced, but hypochlorite itself decomposes at high temperatures, and there is room for improvement in product yield relative to raw material chlorine.

  On the other hand, a method using citric acid and various salts thereof to neutralize by-product hydrochloric acid has also been proposed (Patent Document 4). However, since these become impurities, their use and cleaning are very expensive. There was also room for improvement.

Thus, in the production of conventional CPVC, 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 technological development to improve these balances, It has long been a challenge for those skilled in the art.
Japanese Examined Patent Publication No. 46-17128 JP 2001-11116 A JP 2004-099669 A US Pat. No. 5,359,011

  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.

That is, the present invention
A water slurry of a chlorinated vinyl chloride resin obtained by chlorinating a vinyl chloride resin and a solvent having a solubility parameter of 16 to 20 (MPa) ^1/2 and a saturated solubility of water of 1% or less are mixed. A method for producing a chlorinated vinyl chloride resin (claim 1),
2. A solid resin is obtained by mixing a chlorinated vinyl chloride resin and a solvent, stirring and mixing, separating an oil phase and an aqueous phase, removing the solvent on the oil phase side and drying. Regarding a method for producing a chlorinated vinyl chloride resin (claim 2),
3. The method for producing a chlorinated vinyl chloride resin according to claim 1 or 2, wherein the solvent is a solvent containing a halogenated hydrocarbon (claim 3).

  According to the present invention, hydrochloric acid produced as a by-product in the chlorination reaction can be efficiently removed.

  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. Among them, a polyvinyl chloride single resin having a viscosity average polymerization degree of 350 to 1250 is preferably used. The use of a single polyvinyl chloride resin having a viscosity average polymerization degree 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.

  It is desirable to obtain a chlorinated vinyl chloride resin by chlorinating the vinyl chloride resin thus obtained 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 solution, 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. Even when chlorinating at a resin concentration of 10% by weight or less, it is necessary to balance the production cost. However, if the hydrochloric acid concentration can be further reduced and the hydrochloric acid concentration needs to be reduced as much as possible, it is effective. Method. The chlorination reaction is not particularly limited, and a chlorination method in which ultraviolet rays are irradiated with a mercury lamp, a chlorination method using a catalyst, a method of applying heat, or a combination thereof is possible.

  For example, a chlorination reactor that irradiates ultraviolet rays with a mercury lamp is not particularly limited. However, a mercury lamp is additionally provided if the method is to irradiate ultraviolet rays with a stirrer, cooling jacket, chlorine supply device, or mercury lamp. It only has to be done. Since a large amount of hydrochloric acid is generated 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 solvent used should just have a solubility parameter in the range of 16-20 (MPa) ^1/2 .

  Here, the solubility parameter is a physical property generally used as an index indicating the solubility of a solvent in a solvent or in a solid substance, as described in “Solvent Pocket Book” edited by Organic Synthetic Chemistry Association, Sobunsha. It is a parameter.

When the solubility parameter is in the range of 16 (MPa) ^{1/2 to} 20 (MPa) ^1/2 , it is preferable from the viewpoint of compatibility with the chlorinated vinyl chloride resin and hydrochloric acid removal effect. Moreover, since solubility parameter of from 18.5 to 19.3 ^(MPa) within ^1/2 of the range to be close to the solubility parameter value of the chlorinated vinyl chloride resin (19.0 ^{(MPa) 1/2),} chlorinated chloride The vinyl resin may be dissolved and a good resin powder product may not be obtained. However, since it has hydrochloric acid removal performance, it can be removed by methods such as stripping, thin film evaporator, and extruder treatment with a devolatilizing vent. A treatment method that can be appropriately used can be used as long as the object of the present invention is achieved, such as re-granulation to obtain a resin powder.

  Further, the saturated solubility of water in the solvent used means the saturated solubility of water in the solvent at 25 ° C. atmosphere.

  If the saturated solubility of water is 1% or less, the aqueous hydrochloric acid solution and the solvent filling the resin surface are preferably replaced from the viewpoint of hydrochloric acid removal effect.

  As used herein, the solvent means a substance that becomes a solvent in a solution in handling a solution that is normally in a liquid phase, as described in “Solvent Pocket Book” edited by the Society of Synthetic Organic Chemistry, Sobunsha. In the present application, it refers to a solvent as a solvent for a chlorinated vinyl chloride resin.

  The solvent species to be used is not particularly limited, but a halogenated hydrocarbon having a specific gravity of 1 or more is preferable so that the oil phase containing the resin after removal of hydrochloric acid and the aqueous phase containing hydrochloric acid can be easily separated.

  The halogenated hydrocarbon is not particularly limited. For example, chloroform, ethyl chloride, butyl chloride, hexyl chloride, methyl chloride, methylene chloride, chlorobenzene, chloroform, carbon tetrachloride, ethylene chloride, 1,1,1-trichloroethane, 1 , 1,2-trichloroethane, trichloroethylene, 1,1,2,2-tetrachloroethane, 1,2-dichloropropane, butyl chloride, allyl chloride, amyl chloride, isopropyl chloride, ethyl chloride, hexyl chloride, 1,1-dichloroethane 1,2-dichloroethane, 1,1-dichloroethylene, 1,2-dichloroethylene, dibromopentane, allyl bromide, isopropyl bromide, ethyl bromide, butyl bromide, propyl bromide, methyl bromide, tetrachloroethylene, bromochloroethane Etc. Can. These may be used singly or may be used as a mixed solvent with other solvent groups in view of the balance between solubility parameter and specific gravity. Among these, when used alone, chloroform, 1,1,1-trichloroethane, carbon tetrachloride, 1,2-dichloropropane, butyl chloride and the like can be suitably used from the viewpoint of ease of subsequent separation.

  Other solvents to be mixed are not particularly limited, but hydrocarbons such as xylene, cyclohexane, cyclohexene, cyclopentane, toluene, butane, propane, hexane, heptane, benzene, pentane, methylcyclohexane, methylcyclopentane, crown Ethers such as ether, furan, methylfuran, monochlorodiethyl ether, ketones such as methyl isobutyl ketone, methyl ethyl ketone, methyl-n-butyl ketone, methyl-n-propyl ketone, isoamyl formate, isobutyl formate, butyl formate, hexyl formate, Amyl acetate, allyl acetate, isoamyl acetate, isobutyl acetate, isopropyl acetate, ethyl acetate, n-butyl acetate, s-butyl acetate, propyl acetate, amyl lactate, methyl propionate, dii malonate Propyl, isopropyl butyrate, ethyl butyrate, and the like esters such as methyl butyrate. Of these, cyclohexane, hexane, toluene and the like can be suitably used from the viewpoint of cost and safety.

  As a method of mixing the solvent and the chlorinated vinyl chloride resin, a method using a stirring tank is generally used, but a method using line mixing such as a static mixer, a mill or various mixers may be used. The form of the water slurry of the chlorinated vinyl chloride resin to be mixed may be in the form of a slurry in the reactor or in the form of a cake by a method such as filtration or centrifugation. Moreover, the mixing method may be a method in which a solvent is charged into a reactor containing water slurry by a pump, or a cake-like resin that has been filtered or centrifuged with respect to a solvent already charged in another tank is supplied to the tank. It does not matter how you do it.

  The mixing ratio of the chlorinated vinyl chloride resin and the solvent is not particularly limited, but is preferably 10 to 1000 parts by weight with respect to 100 parts by weight of the resin solids from the viewpoint of production cost and easy handling of the solvent slurry after mixing. More preferred is 20 to 300 parts by weight.

  The temperature at which the solvent and the chlorinated vinyl chloride resin are mixed is not particularly limited, but is preferably 0 to 100 ° C. from the viewpoint of ease of moisture removal and production cost, and more preferably 10 to 80 ° C. from the viewpoint of energy cost.

  As an apparatus for separating the hydrochloric acid water removed from the chlorinated vinyl chloride resin and the solvent containing the resin, static separation using a general tank or centrifugal separation can be used. Further, most of the solvent can be removed from the resin by various filters, centrifuges, and the like. The liquid content of the resin by separating the oil phase from the aqueous phase in this operation and removing the solvent from the resin, that is, the proportion of the liquid volatile component in the resin sent to the dryer accompanying the resin after removal of the solvent is particularly limited. However, it is effective in terms of energy efficiency in drying to be 10 to 50% by weight with respect to the solvent-containing resin. If it is 10 to 35% by weight, the energy efficiency in drying is further increased, which is even better. Moreover, it can also be satisfactorily recovered by a method in which only the solvent-containing resin is taken out by centrifugation or filtration while the two phases of hydrochloric acid and solvent are mixed.

  Various dryers can be used for drying the resin containing the solvent. For example, it is possible to obtain a product powder as a solid resin by using a grooved agitation dryer in the conduction heat transfer method and a fluidized dryer in the hot air heat reception method. The solid resin here means a resin after the solvent remaining before drying is volatilized by drying.

  Here, the drying step is a drying operation in which hydrochloric acid is contained in the resin, and even after the solvent is volatilized, a sufficient residence time, that is, a time necessary for drying is taken, or a second-stage dryer is installed. A method of volatilizing hydrochloric acid as prepared can be employed. At this time, if the amount of hydrochloric acid accompanying the dryer together with the resin is small, it is possible to expect the effect that the residence time is further reduced or the necessity of multi-stage dryers is reduced and the durability of the dryer equipment is further increased.

  EXAMPLES Examples are shown below to describe specific embodiments of the present invention in more detail, but these do not limit the present invention at all.

  In the examples, the hydrochloric acid concentration was 25 ° C. The titration amount at the time when the pH of the target sample corresponding to 1 g of the resin was placed in 100 ml of water and titrated with 0.1N sodium hydroxide aqueous solution to become 7.0. , And quantified by subtracting the titer when no sample is added (blank).

Example 1
A reactor with an internal volume of 50 L (inner diameter: 55 cm) equipped with a one-stage eight disk turbine agitating blade having an outer diameter of 19.5 cm, a cooling jacket, an ultraviolet irradiation lamp, and a chlorine gas blowing nozzle (sparger) having a polymerization degree of 670 Charge 15 kg of vinyl chloride resin and 35 kg of ion-exchanged water, perform vacuum degassing and nitrogen replacement in the reactor for a predetermined time while stirring at 500 rpm, then blow chlorine gas into the system and irradiate with ultraviolet rays to chlorinate. Started. 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 UV irradiation was stopped and the chlorination reaction was terminated to obtain a CPVC slurry.

500 ml of the obtained CPVC slurry was placed in a stirring tank having an inner volume of 2 L (inner diameter: 11 cm) equipped with a one-stage six-disc turbine stirring blade having an outer diameter of 5 cm, and then 1,1,1-trichloroethane (solubility parameter 17. 500 ml of 4 (MPa) ^1/2 , saturated solubility of water 500 ppm) was added, and the mixture was allowed to stand after stirring at 600 rpm for 5 minutes. As a result, the oily water was well separated, and all the resin in the slurry was transferred to the solvent phase. The resin-containing solvent phase was extracted from the lower part of the stirring tank, filtered, and the hydrochloric acid concentration contained in the solvent-containing resin was measured. The results are shown in Table 1.

(Example 2)
In the same manner as in Example 1, 500 ml of CPVC slurry was placed in a stirring tank having an inner volume of 2 L equipped with a one-stage six-disc turbine blade having an outer diameter of 5 cm, and chlorobenzene (solubility parameter 19.4 (MPa) ^{1 / 2} , saturation saturation water of 330 ppm) was added, and the mixture was allowed to stand after stirring at 600 rpm for 5 minutes. As a result, the oily water was well separated, and all the resin in the slurry was transferred to the solvent phase. The resin-containing solvent phase was extracted from the lower part of the stirring tank, filtered, and the hydrochloric acid concentration contained in the solvent-containing resin was measured and found to be 7,000 ppm with respect to the resin. The results are also shown in Table 1.

(Example 3)
In the same manner as in Example 1, 500 ml of CPVC slurry was placed in a 2 L stirring tank equipped with a 1-stage 6-disc turbine stirring blade having an outer diameter of 5 cm, while butyl chloride and cyclohexane (mixing ratio in volume ratio). 9: 1) mixed solvent (solubility parameter 16.5 (MPa) ^1/2 , saturated solubility of water 700 ppm) was added in an amount of 500 ml, and the mixture was allowed to stand after stirring at 600 rpm for 5 minutes. As a result, all of the resin in the slurry was transferred to the solvent phase. Since the solvent specific gravity was low, hydrochloric acid water droplets were mixed in the oil phase containing the resin, but when the hydrochloric acid water droplets were removed by filtering the entire volume and measuring the hydrochloric acid concentration contained in the solvent-containing resin, the resin The amount was 4,000 ppm. The results are also shown in Table 1.

(Comparative Example 1)
A resin was obtained by performing the same operation as in Example 1 except that the CPVC slurry was filtered from the lower part of the stirring tank without adding a solvent. As a result, the hydrochloric acid concentration in the water-containing resin was 20,000 ppm. The results are also shown in Table 1.

(Comparative Example 2)
In the same manner as in Example 1, 500 ml of CPVC slurry was placed in a stirring tank having an inner volume of 2 L provided with a 6-stage 1-stage disk turbine stirring blade having an outer diameter of 5 cm, while tetrahydrofuran (solubility parameter 19.0 (MPa) ^{1 / 2} , completely compatible with water), 500 ml was added, and the mixture was stirred for 5 minutes at 600 rpm and allowed to stand. Then, the CPVC resin was dissolved in the solvent phase, and water and tetrohydrofuran were completely compatible, and hydrochloric acid could not be removed. The results are also shown in Table 1.

(Comparative Example 3)
In the same manner as in Example 1, 500 ml of CPVC slurry was placed in a stirring tank having an inner volume of 2 L equipped with a one-stage six-disk turbine stirring blade having an outer diameter of 5 cm, and hexane (solubility parameter 15.1 (MPa) ^{1 / 2} , 500 ml of water insoluble in hexane (50 ppm or less) was added, and the mixture was allowed to stand after stirring at 600 rpm for 5 minutes. After standing, the water phase and the oil phase could be easily separated, but the resin did not migrate to the solvent phase and remained in hydrochloric acid water, and the hydrochloric acid concentration in the water-containing resin was 20,000 ppm, and a low hydrochloric acid concentration resin was obtained. There wasn't. The results are also shown in Table 1.

As described above, the CPVC resin obtained in Examples 1 and 2 has a low hydrochloric acid concentration after filtration, and the load of removing hydrochloric acid in the subsequent drying treatment could be reduced by the method of the present invention. .

Claims (3)

A water slurry of a chlorinated vinyl chloride resin obtained by chlorinating a vinyl chloride resin and a solvent having a solubility parameter of 16 to 20 (MPa) ^1/2 and a saturated solubility of water of 1% or less are mixed. A method for producing a chlorinated vinyl chloride resin characterized by the above.   2. A solid resin is obtained by mixing a chlorinated vinyl chloride resin and a solvent, stirring and mixing, separating an oil phase and an aqueous phase, removing the solvent on the oil phase side and drying. A method for producing a chlorinated vinyl chloride resin.   The method for producing a chlorinated vinyl chloride resin according to claim 1 or 2, wherein the solvent is a solvent containing a halogenated hydrocarbon.