JP2006328165A - Method for producing chlorinated polyvinyl chloride-based resin - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for producing chlorinated polyvinyl chloride-based resin excellent in productivity and suppressed in generation of unstable structures to have excellent heat stability, especially for producing chlorinated polyvinyl chloride-based resin having ≥65 wt.% chlorine content. <P>SOLUTION: The method for producing chlorinated polyvinyl chloride-based resin comprises performing chlorination in the range of 0.010-0.020 kg/PVC-kg×5 min chlorine consumption rate (chlorine consumption amount per 1 kg raw material vinyl chloride-based resin during 5 min) at the time when chlorine content of the chlorinated polyvinyl chloride-based resin is by 5 wt.% lower than the final chlorine content, then gradually decreasing the chlorine consumption rate (chlorine consumption amount per 1 kg raw material vinyl chloride-based resin during 5 min) and performing chlorination in the range of 0.005-0.015 kg/PVC-kg×5 min chlorine consumption rate (chlorine consumption amount per 1 kg raw material vinyl chloride-based resin during 5 min) at the time when the chlorine content is by 3 wt.% lower than the final chlorine content. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for producing a chlorinated vinyl chloride resin, and in particular, in the production of a chlorinated vinyl chloride resin having a chlorine content of 65% by weight or more used for high heat resistance applications, while maintaining productivity. This is a method for producing a chlorinated vinyl chloride resin in which the reaction is controlled in order to obtain a resin excellent in thermal stability while suppressing the generation of an unstable structure as much as possible.

  Conventionally, a chlorinated vinyl chloride resin (hereinafter referred to as “CPVC”) is produced by post-chlorination of a vinyl chloride resin (hereinafter referred to as “PVC”). CPVC has features such as flame resistance, weather resistance, and chemical resistance, which are the advantages of PVC, and has improved mechanical properties at high temperatures, which are said to be disadvantages of PVC, and is useful as a resin. It is used for various purposes.

  That is, CPVC has the excellent flame retardancy, weather resistance, chemical resistance, etc. of PVC as it is, and further, the heat deformation temperature is 20-40 ° C. higher than PVC, so the upper limit temperature at which PVC can be used Is around 60-70 ° C., CPVC can be used even near 100 ° C., and is used for heat-resistant pipes, heat-resistant sheets, heat-resistant industrial plates and the like.

  As a method for producing CPVC, generally, a method is used in which PVC is suspended in an aqueous medium, and energy is applied by light or heat to chlorinate the PVC. The chlorination rate is increased when a large amount of light energy or heat energy is applied, but there is a disadvantage that the formation of an unstable structure is promoted and the thermal stability is poor.

In order to eliminate the above disadvantages, a method of controlling the reaction rate by using hydrogen peroxide has been proposed. For example, polyvinyl chloride is suspended in an aqueous medium in a sealable container, the inside of the container is decompressed, and then chlorine is introduced into the container to chlorinate polyvinyl chloride at a temperature of 90 to 140 ° C. A method in which hydrogen peroxide is added at a rate of 5 to 50 ppm / hr with respect to polyvinyl chloride when the chlorine content of the polyvinyl chloride during the reaction reaches 60% by weight or more during the chlorination process. There has been proposed a method for producing a chlorinated vinyl chloride resin characterized by starting the process (for example, see Patent Document 1).
JP 2001-151815 A

  However, the method for producing the chlorinated vinyl chloride resin controls the reaction rate when reaching a constant chlorine content of 60% by weight regardless of the chlorine content of the CPVC to be produced. When manufacturing CPVC used for applications (for example, CPVC with a chlorine content of 65% by weight or more), the reaction rate decreases drastically as the chlorine content increases. The balance between productivity and productivity was insufficient.

  In view of the above-mentioned problems of the prior art, the present invention is a chlorinated vinyl chloride resin excellent in productivity and excellent in thermal stability by suppressing the formation of unstable structures, in particular, the chlorine content is 65% by weight or more. An object of the present invention is to provide a method for producing a chlorinated vinyl chloride resin.

  In the method for producing a chlorinated vinyl chloride resin of the present invention, a vinyl chloride resin is dispersed in an aqueous medium in a sealable reaction vessel, the pressure in the reaction vessel is reduced, and then chlorine is introduced into the vessel for chlorination. A method for producing a chlorinated vinyl chloride resin for chlorinating a vinyl resin, wherein chlorination is performed when the chlorine content of the chlorinated vinyl chloride resin reaches 5% by weight from the final chlorine content, Chlorine consumption rate (chlorine consumption for 5 minutes per 1 kg of raw vinyl chloride resin) is in the range of 0.010 to 0.020 kg / PVC-Kg · 5 min, then chlorine consumption rate (1 kg of raw vinyl chloride resin) Chlorine consumption for 5 minutes per 1 kg of raw material vinyl chloride resin. Chlorination at the time when the final chlorine content reached 3% by weight was gradually reduced. )But And carrying out a range of .005~0.015kg / PVC-Kg · 5min.

  The PVC used in the present invention is a vinyl chloride homopolymer or a copolymer of vinyl chloride as a main component (including 50% by weight or more) and a vinyl monomer copolymerizable with vinyl chloride.

  Examples of vinyl monomers copolymerizable with vinyl chloride include vinyl esters such as vinyl acetate and vinyl propionate; (meth) acrylates such as methyl (meth) acrylate and ethyl (meth) acrylate; ethylene and propylene (Meth) acrylic acid, maleic anhydride, acrylonitrile, styrene, vinylidene chloride, and the like.

  When the average particle size of the PVC becomes small, handling becomes difficult, and when the average particle size becomes large, time is required for the chlorination reaction, so 100 to 200 μm is preferable. The average degree of polymerization of PVC is preferably 500 to 2000, which is excellent in moldability.

  The method for producing the PVC is not particularly limited, and examples thereof include a suspension polymerization method, an emulsion polymerization method, and a bulk polymerization method.

  In the suspension polymerization, for example, a vinyl chloride monomer, an aqueous medium, a dispersing agent and a polymerization initiator are charged into a polymerization vessel, and the polymerization reaction is performed by raising the temperature to a predetermined polymerization temperature. After the rate reaches a predetermined ratio of 70 to 90% by weight, cooling, exhaust gas, and demonomer treatment are performed to obtain a slurry containing PVC, and the slurry is dehydrated and dried to obtain PVC.

  Examples of the dispersant include water-soluble celluloses such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and hydroxypropyl methyl cellulose; water-soluble polymers such as partially saponified polyvinyl alcohol, polyethylene oxide, acrylic acid polymer, and gelatin; sorbitan monolaur And water-soluble emulsifiers such as polyoxyethylene sorbitan monolaurate.

  Examples of the polymerization initiator include lauroyl peroxide; peroxycarbonate compounds such as diisopropyl peroxycarbonate, di-2-ethylhexyl peroxycarbonate, diethoxyethyl peroxycarbonate; α-cumylperoxyneodecanate, t -Peroxy ester compounds such as butyl peroxyneodecanate, t-butyl peroxypivalate, t-hexyl peroxyneodecanate; 2,2-azobisisobutyronitrile, 2,2-azobis-2, Examples thereof include azo compounds such as 4-dimethylvaleronitrile and 2,2-azobis (4-methoxy-2,4-dimethylvaleronitrile).

  In addition, polymerization modifiers, chain transfer agents, PH regulators, antistatic agents, cross-linking agents, stabilizers, fillers, antioxidants, scale inhibitors, etc. that are commonly used for vinyl chloride polymerization may be added. Good.

  In the method for producing a chlorinated vinyl chloride resin of the present invention, a vinyl chloride resin is dispersed in an aqueous medium in a sealable reaction vessel, the pressure inside the vessel is reduced, and then chlorine is introduced into the reaction vessel. Chlorinate vinyl chloride resin.

  As the reaction vessel, for example, a sealable pressure vessel equipped with a stirrer, a heating device, a cooling device, a decompression device, a light irradiation device and the like is preferable.

  In order to chlorinate PVC, first, PVC and an aqueous medium are supplied into a sealable reaction vessel, and the PVC is dispersed in the aqueous medium by stirring. Next, the pressure in the reaction vessel is reduced to remove oxygen, and chlorine is introduced into the reaction vessel to chlorinate PVC.

  The reduced pressure is preferably controlled so that the amount of oxygen in the reaction vessel is 100 ppm or less because the control of the chlorination reaction is hindered when a large amount of oxygen is present. Since the rate of progress of the chemical reaction is slow, if it increases, a large amount of unreacted chlorine remains even if the reaction is completed, so it is not economical, so supply the chlorine partial pressure in the reaction vessel to be 0.03 to 0.5 MPa. Preferably it is done.

  Chlorination is performed by light irradiation or heating, but light irradiation may be performed while heating. The reaction temperature in the case of light irradiation is preferably 40 to 80 ° C. The reaction temperature in the case of chlorination only by heating decreases the chlorination rate when the reaction temperature is lowered, and in parallel with the chlorination reaction when it is too high. Since dehydrochlorination reaction occurs and the resulting CPVC comes to be colored, it is preferably 70 to 140 ° C, more preferably 100 to 135 ° C.

  Further, hydrogen peroxide may be added without irradiating light during chlorination. If the amount of hydrogen peroxide is reduced, the effect of improving the chlorination rate is lost, and if the amount is increased, the heat resistance of the obtained CPVC is lowered. Therefore, 5 to 500 ppm per hour is added to PVC. preferable. The reaction temperature when hydrogen peroxide is added is preferably 60 to 140 ° C., more preferably 65 to 110 ° C., because the chlorination rate is improved by adding hydrogen peroxide.

  The rate of chlorination can be controlled by the amount of light irradiation, the reaction temperature, and the amount of hydrogen peroxide added. However, the productivity decreases when the rate is slow, and the dehydrochlorination reaction occurs when the rate is fast. Colored and heat resistance is reduced, so the average chlorine consumption rate (chlorine consumption for 5 minutes per 1 kg of raw vinyl chloride resin) is set to 0.005-0.05 kg · PVC-kg · min. Preferably it is done.

  And in the manufacturing method of the chlorinated vinyl chloride resin of the present invention, the chlorination at the time when the chlorine content of the chlorinated vinyl chloride resin reaches 5% by weight from the final chlorine content, the chlorine consumption rate (Chlorine consumption for 5 minutes per 1 kg of raw material vinyl chloride resin) is in the range of 0.010 to 0.020 kg / PVC-Kg · 5 min, and then the chlorine consumption rate (5 per kg of raw material vinyl chloride resin) Chlorination at the time when the final chlorine content has reached 3% by weight, the chlorine consumption rate (5 minutes of chlorine consumption per kg of raw vinyl chloride resin) is 0. 0.005 to 0.015 kg / PVC-Kg · 5 min.

  As described above, the method for controlling the chlorine consumption rate includes light irradiation, reaction temperature, addition of hydrogen peroxide, and the like. Light irradiation loses energy as the irradiation distance becomes longer, so the reaction proceeds easily only in the vicinity of the light irradiation device, making it difficult to maintain a uniform reaction. To overcome this, it is necessary to greatly increase the stirring efficiency. To that end, equipment modification is necessary. In addition, increasing the light irradiation intensity requires enhancement of the light irradiation device capacity, but it is difficult to change easily because the increase in light irradiation intensity requires an increase in the size of the equipment or the addition of the light irradiation device. Not economical.

  In addition, when the temperature is higher than the initial reaction (above the glass transition temperature of PVC), the chlorination rate is increased, but at the same time, a dehydrochlorination reaction of PVC itself occurs, and the temperature is set within a range that does not adversely affect the thermal stability. Since this is necessary, the control range of the reaction temperature is narrowed. In addition, there are many facilities such as reaction vessels that can withstand high temperatures and peripheral facilities, which is not economical.

  When hydrogen peroxide is used as a catalyst for the chlorination reaction, the reaction rate can be controlled by the concentration of hydrogen peroxide and the addition speed. In particular, hydrogen peroxide is quickly and uniformly dispersed in an aqueous medium, and the variable addition rate can be easily controlled by a pump or the like, so it is very suitable for control in accordance with the progress of chlorination.

  The chlorination rate varies under the same conditions depending on the progress of chlorination. As the chlorination progresses, the reaction proceeds preferentially from the position where chlorine is easily added in the PVC structure, and when the chlorine content exceeds a certain level, the energy required for adding chlorine is large due to the structure. This is because more complicated reactions such as reactions other than the addition of chlorine such as dehydrochlorination of unstable chlorine occur simultaneously.

  Therefore, at the initial stage of the chlorination reaction, the chlorination rate can be maintained sufficiently high even with ordinary light irradiation and heating temperature alone, but these energy sources are insufficient from the middle to the later stage of the chlorination reaction, and the chlorination rate is reduced. It is known to be extremely slow. In order to supplement this, it is possible to improve the reaction rate by adding a peroxide such as hydrogen peroxide as a catalyst.

  When hydrogen peroxide is added at the initial stage of the chlorination reaction, the reaction rate is naturally faster than usual, and the chlorination reaction time itself can be shortened. However, if the reaction rate becomes too fast, an exothermic reaction occurs. Since the dehydrochlorination reaction that usually occurs in the latter stage of the chlorination reaction tends to occur from the beginning, CPVC has more unstable structures such as double bonds and branching than usual, and the most important initial colorability and thermal stability, etc. Performance decreases.

  From mid to late chlorination reaction, for example, by adding hydrogen peroxide, it can be controlled so as not to reduce the reaction rate, but if it is not added, it takes longer to reach the product chlorine content. Productivity is greatly deteriorated. Even if the heating temperature is increased to maintain productivity, the effect is small, and the thermal stability due to the increased thermal history received during the chlorination reaction time is lowered.

  For example, by adding hydrogen peroxide, the progress of chlorination (chlorine content) and the rate of chlorine consumption are controlled to improve productivity, suppress the formation of unstable structures, minimize the acceptance of thermal history, etc. It becomes possible to obtain CPVC excellent in thermal stability.

  In the above-mentioned CPVC manufacturing method (for example, see Patent Document 1), productivity and initial colorability are improved by controlling the chlorine consumption rate when the chlorine content reaches 60% by weight. When applied even to products with a chlorine content of 65% by weight or more, it is effective for performance such as thermal stability, but in terms of productivity, the higher the chlorine content, It has dropped to. This is because the reaction rate is set to be constant regardless of the chlorine content of CPVC.

  In the present invention, the chlorine content of chlorinated PVC is controlled in two stages, 5 wt% before and 3 wt% before the chlorine content of CPVC to be manufactured, while ensuring productivity. Stable structure was suppressed.

  That is, when the chlorine content of CPVC reaches 5% by weight before the final chlorine content, the chlorine consumption rate (5 minutes of chlorine consumption per 1 kg of the raw vinyl chloride resin) is 0.010. 〜0.020kg / PVC-Kg ・ 5min. After that, the chlorine consumption rate (chlorine consumption for 5 minutes per 1kg of raw material vinyl chloride resin) is gradually decreased and 3% by weight from the final chlorine content. Chlorination at the point of time when the chlorine consumption rate is reached in a range of 0.005 to 0.015 kg / PVC-Kg · 5 min when the chlorine consumption rate (chlorine consumption for 5 minutes per 1 kg of the raw material vinyl chloride resin) is CPVC excellent in heat stability can be obtained by suppressing the formation of unstable structures.

  The CPVC production method is particularly suitable for producing CPVC having a chlorine content of 65% by weight or more. However, the higher the chlorine content, the lower the productivity and the generation of many unstable structures. As a result, a decrease in thermal stability occurs, and in order to achieve both productivity and thermal stability, it is necessary to control the chlorination rate more finely.

  Therefore, when manufacturing CPVC with a final chlorine content of 65% by weight or more and less than 70% by weight, the chlorine from the time when the final chlorine content reaches 5% by weight to the time when it reaches 3% by weight. Chlorine consumption rate (chlorine consumption for 5 minutes per 1 kg of raw vinyl chloride resin) is in the range of 0.010 to 0.015 kg / PVC-Kg · 5 min. Chlorination at the time when 3% by weight of the final chlorine content was reached, and the chlorine consumption rate (chlorine for 5 minutes per kg of vinyl chloride resin) The consumption) is preferably in the range of 0.005 to 0.010 kg / PVC-Kg · 5 min.

  In addition, when manufacturing CPVC with a chlorine content of 70% by weight or more, the productivity is further lowered, and an unstable structure is generated regardless of the reaction rate. The decrease in

  Therefore, when manufacturing CPVC having a final chlorine content of less than 70% by weight, the chlorination at the time when the final chlorine content has reached 5% by weight is reduced by the chlorine consumption rate (5 per kg of the raw vinyl chloride resin). Chlorination at a time when the final chlorine content reaches 3% by weight, and the chlorine consumption rate (raw material vinyl chloride) is 0.15 to 0.020 kg / PVC-Kg · 5 min. (Chlorine consumption for 5 minutes per 1 kg of the resin) is preferably performed in the range of 0.005 to 0.015 kg / PVC-Kg · 5 min.

  The structure of the method for producing the chlorinated vinyl chloride resin of the present invention is as described above, and the productivity is excellent, and the chlorinated vinyl chloride resin excellent in thermal stability by suppressing the generation of unstable structure, particularly A chlorinated vinyl chloride resin having a chlorine content of 65% by weight or more can be produced.

Examples of the present invention will be described below, but the present invention is not limited to the following examples.
Example 1
Supply 200 parts by weight of ion-exchanged water and 50 parts by weight of PVC with an average polymerization degree of 1000 to a glass-lined reaction vessel with an internal volume of 300 liters, stir to uniformly disperse the PVC in the ion-exchanged water, and then reduce the pressure. The oxygen in the reaction vessel was removed and the temperature was raised to 100 ° C.

  Next, chlorine was supplied into the reaction vessel so that the partial pressure of chlorine was 0.4 MPa, and chlorination reaction was started while adding 0.2 wt% hydrogen peroxide at 320 ppm (/ hour). The reaction was continued until the chlorine content of PVC reached 62% by weight.

  When the chlorine content of chlorinated PVC reaches 62% by weight (before 5% by weight), the addition amount of 0.2% by weight hydrogen peroxide is reduced to 200 ppm (/ hour), and the chlorine consumption rate is 0 .012 kg / PVC-kg · adjusted to 5 min, proceeded with chlorination, and added 0.2 wt% hydrogen peroxide when the chlorine content reached 64 wt% (3 wt% before) Reduced to 150 ppm per hour (/ hour), adjusted to a chlorine consumption rate of 0.008 kg / PVC-kg · 5 min, proceeded with chlorination, and chlorinated for a total of 6.0 hours with a chlorine content of 67 A weight percent CPVC was obtained.

(Example 2)
Supply 200 parts by weight of ion-exchanged water and 50 parts by weight of PVC with an average polymerization degree of 1000 to a glass-lined reaction vessel with an internal volume of 300 liters, stir to uniformly disperse the PVC in the ion-exchanged water, and then reduce the pressure. The oxygen in the reaction vessel was removed and the temperature was raised to 100 ° C.

  Next, chlorine was supplied into the reaction vessel so that the partial pressure of chlorine was 0.4 MPa, and chlorination reaction was started while adding 0.2 wt% hydrogen peroxide at 320 ppm (/ hour). The reaction was continued until the chlorine content of PVC reached 66% by weight.

  When the chlorine content of chlorinated PVC reaches 66 wt% (5 wt% before), the amount of 0.2 wt% hydrogen peroxide added is reduced to 300 ppm (/ hour), and the chlorine consumption rate is 0 .016 kg / PVC-kg · adjusted to 5 min, proceeded with chlorination, and when it reached 68 wt% (3 wt%), the amount of 0.2 wt% hydrogen peroxide added was 200 ppm (/ hour) ), The chlorine consumption rate was adjusted to 0.012 kg / PVC-kg · 5 min, and chlorination proceeded, and chlorination was performed for a total of 9.0 hours to obtain CPVC having a chlorine content of 71 wt%. .

(Comparative Example 1)
Supply 200 parts by weight of ion-exchanged water and 50 parts by weight of PVC with an average polymerization degree of 1000 to a glass-lined reaction vessel with an internal volume of 300 liters, stir to uniformly disperse the PVC in the ion-exchanged water, and then reduce the pressure. The oxygen in the reaction vessel was removed and the temperature was raised to 100 ° C.

  Next, chlorine was supplied into the reaction vessel so that the partial pressure of chlorine was 0.4 MPa, and chlorination reaction was started while adding 0.2 wt% hydrogen peroxide at 320 ppm (/ hour). The reaction was continued until the chlorine content of PVC reached 60% by weight.

  When the chlorine content of the chlorinated vinyl chloride resin reaches 60% by weight (7% by weight), the addition amount of 0.2% by weight hydrogen peroxide is reduced to 150 ppm (/ hour), and the chlorine consumption rate Was adjusted to 0.005 kg / PVC-kg · 5 min, chlorination was advanced, and chlorination was performed for 8.0 hours to obtain CPVC having a chlorine content of 67 wt%.

(Comparative Example 2)
Supply 200 parts by weight of ion-exchanged water and 50 parts by weight of PVC with an average polymerization degree of 1000 to a glass-lined reaction vessel with an internal volume of 300 liters, stir to uniformly disperse PVC in ion-exchanged water, and then reduce the pressure. The oxygen in the reaction vessel was removed and the temperature was raised to 100 ° C.

  Next, chlorine was supplied into the reaction vessel so that the partial pressure of chlorine was 0.4 MPa, and chlorination reaction was started while adding 0.2 wt% hydrogen peroxide at 320 ppm (/ hour). The reaction was continued until the chlorine content of the vinyl chloride resin reached 60% by weight.

  When the chlorine content of chlorinated PVC reaches 60% by weight (11% before), the amount of 0.2% hydrogen peroxide added is reduced to 0.012kg / PVC-kg · 5min. The chlorination was advanced while adjusting so that CPVC with a chlorine content of 67 wt% was obtained by chlorinating for 5.8 hours.

(Comparative Example 3)
Supply 200 parts by weight of ion-exchanged water and 50 parts by weight of PVC with an average polymerization degree of 1000 to a glass-lined reaction vessel with an internal volume of 300 liters, stir to uniformly disperse the PVC in the ion-exchanged water, and then reduce the pressure. The oxygen in the reaction vessel was removed and the temperature was raised to 100 ° C.

  Next, chlorine was supplied into the reaction vessel so that the partial pressure of chlorine was 0.4 MPa, and chlorination reaction was started while adding 0.2 wt% hydrogen peroxide at 320 ppm (/ hour). The reaction was continued until the chlorine content of the vinyl chloride resin reached 60% by weight.

  When the chlorine content of chlorinated PVC reaches 60% by weight (before 11% by weight), the addition amount of 0.2% by weight hydrogen peroxide is reduced to 150 ppm (/ hour), and the chlorine consumption rate is 0 The chlorination was advanced by adjusting to 0.005 kg / PVC-kg · 5 min and chlorinated for 18 hours to obtain a CPVC having a chlorine content of 71 wt%.

  100 parts by weight of the obtained CPVC, 1.5 parts by weight of an organic tin-based stabilizer (trade name “ONZ-100F” manufactured by Sansha Co., Ltd.), an MBS impact modifier (trade name “M511” manufactured by Kaneka Corporation) ) 8 parts by weight, acrylic processing aid (manufactured by Mitsubishi Rayon Co., Ltd., trade name “Metabunlen P-550”) 1 part by weight and stearic acid lubricant (manufactured by Riken Vitamin Co., trade name “SL800”) 0.5 parts by weight The resulting resin composition was wound around a roll with a 195 ° C. roll and then kneaded for 3 minutes. Using the obtained roll sheet, a heat aging test (200 ° C., 10 × 140 minutes), which is a static thermal stability test, was performed, and the time (minutes) until blackening was measured.

Generated by taking 1 g of the obtained CPVC into a 10 ml glass test tube, heating in a 190 ° C oil bath under a nitrogen stream, trapping hydrochloric acid generated from CPVC in water, and measuring the pH of the water The time taken for the amount of hydrochloric acid to reach 5,000 ppm was measured.
Table 1 shows the chlorination conditions, blackening time, and dehydrochlorination time of each example and comparative example.

Claims (3)

  Disperse vinyl chloride resin in an aqueous medium in a sealable reaction vessel, depressurize the reaction vessel, and then introduce chlorine into the vessel to chlorinate the vinyl chloride resin. Chlorination at the time when the chlorine content of the chlorinated vinyl chloride resin has reached 5% by weight from the final chlorine content, the chlorine consumption rate (5 minutes per kg of raw vinyl chloride resin) Of chlorine consumption) is in the range of 0.010 to 0.020 kg / PVC-Kg · 5 min, and thereafter the chlorine consumption rate (chlorine consumption for 5 minutes per kg of the raw vinyl chloride resin) is gradually reduced, Chlorination when the final chlorine content reaches 3% by weight is the chlorine consumption rate (chlorine consumption for 5 minutes per 1 kg of the raw vinyl chloride resin) is 0.005 to 0.015 kg / PVC-Kg · 5 Method for producing a chlorinated vinyl chloride resin, which comprises carrying out a range of in.   A method for producing a chlorinated vinyl chloride resin having a final chlorine content of 65% by weight or more and less than 70% by weight, wherein the chlorine content of the chlorinated vinyl chloride resin is 5% by weight before the final chlorine content. Chlorination at the time of reaching is performed in a range of chlorine consumption rate (chlorine consumption for 5 minutes per 1 kg of raw material vinyl chloride resin) in the range of 0.010 to 0.015 kg / PVC-Kg · 5 min. The rate (chlorine consumption for 5 minutes per 1 kg of raw vinyl chloride resin) is gradually reduced, and chlorination at the point when it reaches 3% by weight from the final chlorine content, the chlorine consumption rate (1 kg of raw vinyl chloride resin) 5. The method for producing a chlorinated vinyl chloride resin according to claim 1, wherein the chlorine consumption per 5 minutes is within a range of 0.005 to 0.010 kg / PVC-Kg · 5 min.   A method for producing a chlorinated vinyl chloride resin having a final chlorine content of 70% by weight or more, wherein the chlorine content of the chlorinated vinyl chloride resin reaches 5% by weight before the final chlorine content. The chlorine consumption rate (chlorine consumption for 5 minutes per kg of raw vinyl chloride resin) is in the range of 0.015 to 0.020 kg / PVC-Kg · 5 min, and then the chlorine consumption rate (raw vinyl chloride) Chlorine consumption at 5 minutes per 1 kg of raw material vinyl chloride resin is gradually reduced, and chlorination at the time when the final chlorine content reaches 3% by weight is reduced. The method for producing a chlorinated vinyl chloride resin according to claim 1, wherein the chlorine consumption is performed in the range of 0.005 to 0.015 kg / PVC-Kg · 5 min.