KR20190005667A - Method for preparing polyvinylchloride - Google Patents

Abstract

The present invention relates to a method of manufacturing a vinyl chloride based polymer, comprising: a step of first polymerizing a first vinyl chloride based monomer at a first temperature in the presence of an initiator; a step of second polymerizing while reducing the temperature to a second temperature, which is lower than the first temperature; and a step of third polymerizing at the second temperature. Thus, during the first polymerization or the second polymerization, addition of a second vinyl chloride based polymer is initiated but the addition is performed before 70 minutes have elapsed from a start of the first polymerization. A purpose of the present invention is to provide the method for manufacturing a vinyl chloride based polymer capable of effectively controlling heat generation during polymerization by performing non-isothermal polymerization which changes polymerization temperature at the beginning, middle, and end of the polymerization in phases.

Description

METHOD FOR PREPARING POLYVINYLCHLORIDE [0002]

The present invention relates to a process for producing a vinyl chloride polymer, and more particularly, to a process for producing a vinyl chloride polymer in which non-isothermal polymerization is carried out, and a vinyl chloride monomer is further added at the early stage or middle stage of polymerization.

The vinyl chloride polymer is the most widely used synthetic resin among the thermoplastic resins. The vinyl chloride monomer used as a raw material for the production of the vinyl chloride polymer is polymerized in a batch reactor. As the reaction initiator, an organic peroxide, which is an explosive substance, is used. As the additive, a dispersant (emulsifier) and an antioxidant are used.

Examples of the polymerization method of the vinyl chloride polymer include a suspension polymerization method, an emulsion polymerization method and a bulk polymerization method. The suspension polymerization method and the emulsion polymerization method are a method in which a vinyl chloride monomer is suspended (emulsified) in water and then reacted with an initiator, whereas the bulk polymerization method is a method in which a vinyl chloride monomer and an initiator are reacted directly without using water and a dispersant .

The suspension polymerization method has a high conversion rate to vinyl chloride polymer and low operation cost. It is easy to recover unreacted vinyl chloride monomer after the polymerization process, and because of the coating system, scale accumulation amount in the reactor is small and maintenance is easy . At present, the suspension polymerization method has significant advantages in the mass production trend.

When a vinyl chloride polymer is produced by the suspension polymerization method, the amount of heat generated is small at the initial stage of polymerization in the production of a vinyl chloride polymer having a degree of polymerization of 1000 or more, and the amount of heat generated at the end of the polymerization is greatly increased. As a result, the heat removal flow rate of the reflux condenser is maximized at the end. Because of this heat-releasing pattern, there is a problem that the amount of the monomer and the amount of the initiator are limited, and the productivity is lowered.

Accordingly, studies have been continued to improve the heat-removing efficiency in the production of the vinyl chloride-based polymer while not deteriorating the physical properties of the vinyl chloride-based polymer produced therefrom.

JP2016-188334A

An object of the present invention is to provide a method for producing a vinyl chloride-based polymer capable of effectively controlling heat generation at the time of polymerization by performing non-isothermal polymerization in which polymerization temperatures at the beginning, middle, and end of the polymerization are changed stepwise.

Another object of the present invention is to provide a method for producing a vinyl chloride-based polymer having a property equivalent to that of a vinyl chloride-based polymer prepared by isothermal polymerization and having a reduced reaction time and improved productivity .

In order to solve the above-mentioned problems, the present invention provides a method for producing a vinyl chloride-based copolymer, comprising the steps of: first polymerizing a first vinyl chloride monomer at a first temperature in the presence of an initiator; And a second polymerizing while being warmed to a second temperature lower than the first temperature; And a third polymerization at the second temperature, wherein during the first polymerization or the second polymerization, the introduction of the second vinyl chloride monomer is started, but before the elapse of 70 minutes from the start of the first polymerization, Based on the weight of the vinyl chloride polymer.

Further, the present invention is a suspension-polymerized vinyl chloride polymer, wherein the vinyl chloride polymer has a degree of polymerization of 980 or more and an average particle diameter of more than 140 占 퐉.

In the method for producing a vinyl chloride polymer of the present invention, heat generation during the polymerization reaction can be easily controlled by changing the polymerization temperature in the early stage of polymerization, middle stage and late stage.

In addition, the production method of the vinyl chloride polymer of the present invention can increase the charge volume and the amount of the initiator in the reactor, thereby shortening the reaction time and improving the productivity.

The vinyl chloride-based polymer produced by the process for producing a vinyl chloride-based polymer of the present invention has the same level of physical properties as those of the vinyl chloride-based polymer produced by isothermal polymerization, that is, having a degree of polymerization, an apparent specific gravity, Can be improved.

Hereinafter, the present invention will be described in detail in order to facilitate understanding of the present invention.

The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary terms and the inventor may appropriately define the concept of the term in order to best describe its invention It should be construed as meaning and concept consistent with the technical idea of the present invention.

A method for producing a vinyl chloride polymer according to an embodiment of the present invention includes the steps of: first polymerizing a first vinyl chloride monomer at a first temperature in the presence of an initiator; And a second polymerizing while being warmed to a second temperature lower than the first temperature; And a third polymerization at the second temperature, wherein the introduction of the second vinyl chloride monomer can be started during the first polymerization or the second polymerization.

Polymerization of the present invention can mean suspension polymerization, unless otherwise defined.

The suspension polymerization is generally carried out by isothermal polymerization, but in the case of isothermal suspension polymerization, as described above, the calorific value is concentrated immediately before the drop of the reaction pressure at the end of the reaction, and the productivity is lowered due to the amount of monomer input and the amount of initiator there is a problem.

Accordingly, in the present invention, in order to disperse the calorific value at the end of the reaction to the initial stage of the reaction, the temperature at the initial stage of polymerization is increased by controlling the calorific value at the end of polymerization, and the polymerization degree is maintained at the same level as that of the application of isothermal polymerization As a method for preparing a polymer, a non-isothermal polymerization method is proposed which has a reaction activity at the initial stage of polymerization.

Further, the vinyl chloride polymer produced by the non-isothermal polymerization may have a problem of lowering the physical properties, specifically, the apparent specific gravity and the plasticizer absorption rate, as compared with the vinyl chloride polymer produced by isothermal polymerization. However, , The initial stage of the polymerization, the control of the middle stage and the terminal stage, and the control of the partial introduction of the monomers, and the control of the reaction will be described below.

As in the method of producing a vinyl chloride polymer according to one embodiment of the present invention, polymerization can be activated from the beginning of polymerization when the polymerization is carried out at a stepwise lowering temperature, It can be dispersed in early and mid-term. Therefore, it is possible to maintain a relatively uniform heating pattern in the pre-polymerization process, so that it is easy to remove heat from the reactor in which the first to third polymerization processes are performed. In addition, since the polymerization activity is relatively uniform during the pre-polymerization process, it is possible to increase the charging volume and the amount of the initiator in the reactor, thereby shortening the reaction time and improving the productivity.

The first polymerization may be carried out at a first temperature of from 58 to 62 캜, specifically from 59 to 61 캜, more specifically from 59 to 60 캜. When the above-mentioned range is satisfied, it is possible to produce a vinyl chloride-based polymer which realizes the same level of physical properties, particularly a polymerization degree, as that of the vinyl chloride-based polymer produced by isothermal polymerization, without further addition of additives.

The first polymerization may be carried out in the presence of an initiator after the first vinyl chloride monomer is dispersed in water using a dispersant.

The first vinyl chloride monomer may be a vinyl chloride monomer or a mixed monomer containing the vinyl chloride monomer. The mixed monomer may include a vinyl-based monomer copolymerizable with the vinyl chloride monomer. The mixed monomer may include 1 to 50 parts by weight of the vinyl monomer based on 100 parts by weight of the vinyl chloride monomer. When the above-mentioned range is satisfied, the suspension polymerization is stably carried out, and further, the processability of the obtained vinyl chloride resin is stabilized. The vinyl monomer may be an olefin compound such as ethylene or propylene; Vinyl esters such as vinyl acetate and vinyl propionate; Unsaturated nitriles such as acrylonitrile; Vinyl alkyl ethers such as vinyl methyl ether and vinyl ethyl ether; Unsaturated fatty acids such as acrylic acid, methacrylic acid, itaconic acid and maleic acid; And anhydrides of these fatty acids.

The water may be deionized water or pure water.

The dispersant may be contained in an amount of preferably 0.05 to 0.1 part by weight, specifically 0.06 to 0.08 part by weight, more preferably 0.7 to 0.08 part by weight, based on 100 parts by weight of the first vinyl chloride monomer. When the above-mentioned range is satisfied, there is an effect of excellent process stability at the time of polymerization, easy recovery of unreacted monomers after polymerization, and excellent productivity.

The dispersing agent may be at least one selected from the group consisting of water-soluble polyvinyl alcohol, oil-soluble partially saponified polyvinyl alcohol, polyacrylic acid, copolymer of vinyl acetate and maleic anhydride, hydroxypropyl methylcellulose, Gelatin, calcium phosphate, hydroxyapatite, sorbitan monolaurate, sorbitan trioleate, polyoxyethylene, sodium lauryl sulfate (sodium lauryl sulfate) sodium lauryl sulfate, dodecylbenzene sulfonic acid, sodium salt, and sodium dioctylsulfosuccinate may be used.

The initiator may be contained in an amount of preferably 0.05 to 0.1 part by weight, more preferably 0.06 to 0.08 part by weight, and more preferably 0.07 to 0.08 part by weight based on 100 parts by weight of the first vinyl chloride monomer. When the above-mentioned range is satisfied, the stability of the polymerization process is excellent.

The initiator may be an organic peroxide such as dicumyl peroxide, dipentyl peroxide, di (3,5,5-trimethylhexanoyl) peroxide, diacyl peroxides such as peroxide and dilauroyl peroxide; Diisopropyl peroxydicarbonate, di-sec-butyl peroxydicarbonate, di (2-ethylhexyl) peroxydicarbonate, etc. Peroxycarbonates; t-butylperoxy neodecanoate, t-butylperoxy neoheptanoate, t-amyl peroxy neodecanoate, cumyl peroxyneodecanoate, t-butylperoxy neodecanoate, But are not limited to, cumyl peroxy neodecanoate, cumyl peroxy neoheptanoate, 1,1,3,3-tetramethyl butyl peroxyneodecanoate (1,1,3,3 -tetramethylbutyl peroxy neodecanoate); Azo compounds such as azobis-2,4-dimethylvaleronitrile; Sodium persulfate, potassium persulfate, ammonium persulfate, and the like.

The second polymerization may be performed while the temperature is lowered to a second temperature lower than the first temperature. Specifically, the second polymerization may be performed at a temperature of 2 to 6 ° C, more specifically, 2 to 4 ° C lower than the first temperature 2 < / RTI > temperature. If the second polymerization is performed while the temperature is lowered to the second temperature lower than the first temperature, a relatively uniform heating pattern can be maintained in the pre-polymerization process, so that the heat treatment of the reactor in which the first to third polymerization is performed is easy . In addition, since the polymerization activity is relatively uniform during the pre-polymerization process, it is possible to increase the charging volume and the amount of the initiator in the reactor, thereby shortening the reaction time and improving the productivity. In addition, the physical properties of the vinyl chloride polymer as the final product, i.e., the apparent specific gravity and the plasticizer absorption rate, may be equivalent to those of the vinyl chloride polymer produced by isothermal polymerization.

The second polymerization may be initiated after the first polymerization is carried out for 30 to 70 minutes, specifically 30 to 60 minutes, more particularly 40 to 60 minutes. The second polymerization may be performed for 20 to 60 minutes, specifically 30 to 50 minutes, more specifically 40 to 50 minutes.

The starting point of the second polymerization may also be determined by the polymerization conversion ratio. In this case, the case where only the first vinyl chloride monomer is introduced in the first polymerization and the case where a part of the first vinyl chloride monomer and the second vinyl chloride monomer are charged can be categorized.

In the case of the former, when the polymerization conversion ratio of the first vinyl chloride monomer reaches 15 to 35%, specifically 15 to 30%, more specifically 20 to 30%, the second polymerization may be started . In the latter case, the polymerization conversion ratio of the sum of the first vinyl chloride monomer and the second vinyl chloride monomer charged in the first polymerization is 15 to 30%, specifically 20 to 30%, more specifically 20 to 25% , The second polymerization may be initiated.

The polymerization conversion ratio of the sum of the first vinyl chloride monomer and the second vinyl chloride monomer charged in the first polymerization reaches 35 to 55%, specifically 40 to 50%, more specifically 40 to 45% , The second polymerization may be converted to the third polymerization.

On the other hand, the polymerization conversion ratio can be calculated by the following formula.

(%) = (Final polymerization conversion ratio at isothermal polymerization at 58 캜) / (final isopolymerization time at 58 캜) × T (polymerization time at each time point) × 100

As the second polymerization initiation time is delayed and the second polymerization execution time is shortened, the total polymerization time may be shortened, but the physical properties of the vinyl chloride polymer as a final product may be deteriorated. However, if the above-mentioned second polymerization initiation time and the second polymerization execution time, the later-described starting time of the introduction of the second vinyl chloride monomer and the charging time of the second vinyl chloride monomer are satisfied, the entire polymerization time can be shortened , The physical properties of the vinyl chloride polymer as the final product can be realized at the same level as the vinyl chloride polymer produced by isothermal polymerization.

The third polymerization may be terminated when a pressure difference of 1 to 2 kg / cm < 2 > occurs in the initial stage of polymerization, that is, the pressure of the reactor at the start of the first polymerization.

On the other hand, the second vinyl chloride monomer may be added before 70 minutes have elapsed since the start of the first polymerization. Specifically, the second vinyl chloride monomer may be added 70 minutes before 30 minutes after the start of the first polymerization, more specifically, after 40 minutes and 60 minutes before.

The starting point of the introduction of the second vinyl chloride monomer may be limited to the polymerization conversion rate. In this case, when the polymerization conversion rate of the first vinyl chloride monomer is 15 to 30%, specifically 20 to 30%, more specifically, 20 to 25% Lt; / RTI >

And the starting time of the introduction of the second vinyl chloride monomer may be limited in relation to the first polymerization to the third polymerization. In this case, the introduction of the second vinyl chloride monomer may be started during the first polymerization or the second polymerization.

The second vinyl chloride monomer may be continuously added during the first polymerization to the third polymerization from the start of the addition to two or more polymerization reactions. Specifically, when the second vinyl chloride monomer is introduced during the first polymerization, it can be continuously introduced during the first polymerization and the second polymerization or the first polymerization to the third polymerization. Here, the introduction of the second vinyl chloride monomer during the first polymerization may mean that the charging is started after a lapse of a predetermined time after the initiation of the first polymerization.

When the second vinyl chloride monomer is introduced during the second polymerization, it may be continuously introduced during the second polymerization or the second polymerization and the third polymerization. Here, the introduction of the second vinyl chloride monomer into the second polymerization is started when the second polymerization is initiated, and when the second polymerization is initiated, after the elapse of a certain time after the initiation of the second polymerization, It can mean all things.

The second vinyl chloride monomer may be continuously charged for 30 to 60 minutes, particularly 40 to 60 minutes, more specifically 40 to 50 minutes from the start of charging.

The continuous introduction of the second vinyl chloride monomer may be terminated together during or at the end of the second polymerization or the third polymerization.

If the time point of introduction of the vinyl chloride monomer is as long as possible, the polymerization time may be shortened, but the degree of polymerization of the vinyl chloride polymer as a final product may be lowered. Also, if the time point of introduction of the second vinyl chloride monomer is delayed, the physical properties of the vinyl chloride polymer as a final product may be deteriorated. However, if the above-mentioned point of view or the time of injection is satisfied, the polymerization time can be shortened, and the physical properties of the vinyl chloride polymer as a final product can be produced at the same level as the vinyl chloride polymer prepared by isothermal polymerization.

The second vinyl chloride monomer may be added in an amount of 8 to 13 parts by weight, and more preferably 9 to 12 parts by weight, based on 100 parts by weight of the first vinyl chloride monomer. When the above-mentioned range is satisfied, the productivity of the vinyl chloride-based polymer can be improved. In addition, two or more vinyl chloride polymers having different production times, that is, a vinyl chloride polymer prepared from a vinyl chloride monomer and a vinyl chloride polymer made from a vinyl chloride monomer can be simultaneously produced . In this case, the vinyl chloride polymer as a final product may have a rough surface morphology, and as a result, the plasticizer can be easily absorbed.

The first to third polymerizations may be performed in one reactor.

In the method for producing a vinyl chloride polymer of the present invention, radical polymerization can be performed by decomposing an initiator present in the first polymerization. In this case, as the polymerization is carried out, the amount of the residual vinyl chloride monomer is reduced compared to the rate at which the initiator is decomposed to produce the polymer, so that the polymerization conversion rate may be very slow. When the second vinyl chloride monomer is further added during the first polymerization or the second polymerization, the production amount of the polymer can be improved during the same polymerization time.

Since the vinyl chloride polymer prepared according to one embodiment of the present invention is made by non-isothermal polymerization, the network between the primary particles constituting the polymer is relatively strong, and there may be many voids inside. Since the vinyl chloride-based polymer has many voids therein, the vinyl chloride-based polymer can be rapidly melted at a high temperature, and the workability can be excellent.

The vinyl chloride polymer may have a number average degree of polymerization of 980 or more, specifically 980 to 1,100, more specifically 980 to 1,020. The vinyl chloride polymer may have an average particle diameter of 140 to 170 占 퐉, specifically 140 to 160 占 퐉, more specifically 140 to 150 占 퐉.

The number average degree of polymerization means the average number of repeating units in the polymer chain and can be calculated as a ratio of the number average molecular weight to the molecular weight of the repeating unit.

The average particle size was determined by measuring the average particle size measured from the angle of light diffracted according to the particle size when the powder as a sample unit passed through the cell, Particle size distribution value.

Hereinafter, embodiments of the present invention will be described in detail so that those skilled in the art can easily carry out the present invention. The present invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein.

Example  1 to Example  8, Comparative Example  1 to Comparative Example  3

1 m < 3 >, a stirrer located in the polymerization reactor, a reflux condenser connected to the polymerization reactor and for releasing the temperature of the polymerization reaction, and a vinyl chloride recovery unit connected to the reflux condenser and discharging the unreacted vinyl chloride monomer The vinyl chloride monomer was polymerized by the following method using a polymerization apparatus including a pipe.

First, 140 parts by weight of polymerization water, 0.02 part by weight of polyvinyl alcohol having a degree of hydration of 88% as a dispersant, 0.03 part by weight of polyvinyl alcohol having a degree of hydration of 72%, and polyvinyl alcohol having a degree of hydration of 55% , 0.005 part by weight of hydroxypropylmethylcellulose, and 0.088 part by weight of t-butylperoxyneodecarbonate as an initiator were added in one portion, and the inside of the polymerization reactor was degassed by a vacuum pump. Subsequently, 100 parts by weight of a vinyl chloride monomer was added as the first vinyl chloride monomer. After the temperature of the polymerization reactor was raised to the first polymerization temperature shown in Table 1, when the first polymerization temperature was reached, the first polymerization reaction was started and the first polymerization reaction was performed for the time period described in the following Table 1 . The polymerization conversion ratios of the first vinyl chloride monomer when the first polymerization is completed are shown in Table 1 below.

Then, the second polymerization was initiated for the time period shown in the following Table 1 while being kept at the second polymerization temperature. The polymerization conversion ratios of the first vinyl chloride monomer when the second polymerization was completed are shown in Table 1 below.

On the other hand, 10 parts by weight of a vinyl chloride monomer as a second vinyl chloride monomer was added for the period of time shown in the following Table 1 after the time described in the following Table 1 was over after the start of the first polymerization reaction.

Subsequently, when the second polymerization time elapsed, the third polymerization was started at the third polymerization temperature described in Table 1, and the third polymerization was stopped when the internal pressure of the polymerization reactor had a change of 1.0 kg / cm 2 . The time from the start of the third polymerization to the point of time when the third polymerization is stopped and the total polymerization time are shown in Table 1 below. Then, 0.05 part by weight of triethylene glycol-bis- [3- (3-t-butyl-5-methyl-4-hydroxyphenyl) propionate] as an antioxidant was added to the polymerization reactor, Allyl-2-methoxy-phenol) were added. Thereafter, the unreacted monomers and the vinyl chloride polymer slurry were recovered in the polymerization reactor. The vinyl chloride polymer slurry was subjected to a stripping and dehydration process to separate the unreacted vinyl chloride monomer and water, and then dried in a fluidized bed drier at 60 ° C with hot air and screened to obtain a vinyl chloride polymer.

division First polymerization Second polymerization Third polymerization The second vinyl chloride monomer Temperature time polymerization
Conversion Rate time polymerization
Conversion Rate Temperature time Time of injection Injection time Example 1 59 ℃ 60 minutes 30% 30 minutes 45% 57 ℃ 70 minutes 60 minutes 50 minutes Example 2 60 ° C 55 minutes 27% 30 minutes 42% 56 ℃ 62 minutes 55 minutes 50 minutes Example 3 60 ° C 50 minutes 24% 50 minutes 38% 56 ℃ 46 minutes 50 minutes 50 minutes Example 4 60 ° C 40 minutes 19% 40 minutes 38% 56 ℃ 71 minutes 50 minutes 50 minutes Example 5 60 ° C 50 minutes 24% 30 minutes 38% 56 ℃ 64 minutes 40 minutes 50 minutes Example 6 60 ° C 50 minutes 24% 30 minutes 38% 56 ℃ 64 minutes 50 minutes 40 minutes Example 7 61 ℃ 50 minutes 24% 50 minutes 38% 55 ° C 42 minutes 50 minutes 50 minutes Example 8 60 ° C 60 minutes 30% 20 minutes 38% 56 ℃ 43 minutes 50 minutes 50 minutes Comparative Example 1 58 ℃ 165 minutes 80% - - - - 65 minutes 50 minutes Comparative Example 2 59 ℃ 60 minutes 30% 30 minutes 45% 57 ℃ 68 minutes - - Comparative Example 3 59 ℃ 60 minutes 30% 30 minutes 45% 57 ℃ 90 minutes 110 minutes 50 minutes

Polymerization Conversion (%) = 80 (Conversion Rate of Comparative Example 1) / 165 (Polymerization Time of Comparative Example 1) x T (Polymerization Time According to Each Time) x 100

Experimental Example  One: Vinyl chloride series  Measurement of physical properties of polymer

The total polymerization time, number average degree of polymerization and average particle diameter of the vinyl chloride polymers of Examples 1 to 8 and Comparative Examples 1 to 3 were measured by the following measuring methods, and the results are shown in Table 2 Respectively.

1) Number average degree of polymerization: Measured according to ASTM D1243-79.

2) Average Particle Diameter: The average particle size and the particle size measured from the magnitude of the angle of light diffracted according to the particle size when the vinyl chloride polymer powder passed through the cell, The distribution values are shown within the error range.

division Total polymerization time Number average degree of polymerization Average particle diameter (占 퐉) Example 1 160 minutes 1,000 144 Example 2 147 minutes 1,000 146 Example 3 146 minutes 1,000 145 Example 4 151 minutes 1,020 145 Example 5 144 minutes 1,000 145 Example 6 144 minutes 1,000 145 Example 7 142 minutes 980 149 Example 8 143 minutes 980 146 Comparative Example 1 165 minutes 1,000 140 Comparative Example 2 160 minutes 1,000 142 Comparative Example 3 180 minutes 1,000 153

Referring to Table 2, it was confirmed that the vinyl chloride type polymers of Examples 1 to 8 can be shortened in polymerization time up to 38 minutes as compared with the vinyl chloride type polymers of Comparative Examples 1 to 3. That is, as in the present invention, the step of reducing the reaction temperature in the second polymerization process when the polymerization is switched from the first polymerization to the third polymerization, the step of additionally adding the second vinyl chloride monomer, It can be seen that the reaction time of the entire polymerization reaction can be shortened and it is confirmed that the productivity can be improved.

Specifically, it was confirmed that the vinyl chloride type polymers of Examples 1 to 6 were of the same level as the vinyl chloride type polymer of Comparative Example 1 in which the number average degree of polymerization was made by non-isothermal polymerization, The vinyl chloride polymer having a number average degree of polymerization of 980 was obtained although the total polymerization time was decreased because the temperature decrease width during polymerization was somewhat large at 6 ° C. Further, in the case of Example 8, since the second polymerization was performed for a relatively short time, the total polymerization time was reduced, but it was confirmed that the number-average degree of polymerization was lowered.

On the other hand, in Examples 7 and 8 and Examples 1 to 6, as shown in Table 2, the difference in the number average degree of polymerization of about 20 is due to the fact that the melting time is relatively different, And considering the number average degree of polymerization and considering the melting characteristics thereof, it may be necessary to control the temperature range for warming and the polymerization time of the second polymerization.

Experimental Example  2: Vinyl chloride series  Measurement of physical properties of polymer composition

To 100 parts by weight of the vinyl chloride polymers of Examples 1 to 8 and Comparative Examples 1 to 3, 35 parts by weight of dioctyl phthalate (DOP) as a plasticizer, 1 part by weight of barium stearate as a heat stabilizer, 1 part by weight of lactate and 1 part by weight of stearic acid as a lubricant were added and mixed to prepare a vinyl chloride polymer composition.

1) Plasticizer absorption rate [CPA, (% by weight)]: Measured according to ASTM D 3367-95.

2) Fusion time and melting load: Melting time was measured using a Bradender plastograph at 140 rpm and 30 rpm, respectively.

3) Bulk Density (g / cm 3): Measured according to ASTM D 1895-89.

division CPA
(weight%) Melting time
(second) Apparent specific gravity
(g / cm3) Example 1 16.6 107 0.577 Example 2 16.0 110 0.579 Example 3 16.3 110 0.578 Example 4 15.9 113 0.579 Example 5 16.8 101 0.575 Example 6 16.8 100 0.575 Example 7 14.5 112 0.581 Example 8 16.5 108 0.577 Comparative Example 1 14.6 122 0.582 Comparative Example 2 16.0 107 0.561 Comparative Example 3 14.0 126 0.586

With reference to Table 3 above, the vinyl chloride type polymers of Examples 1 to 6 and Example 8 have excellent plasticizers absorption rate, and thus the vinyl chloride type polymer composition thus obtained has a melting time during processing of Comparative Example 1 and Comparative Example Which is shorter than that of Example 3.

In the case of Comparative Example 2, the plasticizer absorption rate and melting time were the same as in Example 1 and the plasticizer absorption rate and melting time were superior to those in Example 7, but the lower specific gravity was lower than those of Examples 1 and 7 I could confirm. Thus, in the case of manufacturing pipes according to Examples 1 and 7 and Comparative Example 2, compared with the pipe of Comparative Example 2, the pipes manufactured in Examples 1 and 7 had an excellent extrusion rate, And the pressure resistance can be excellent.

Claims (14)

Polymerizing the first vinyl chloride monomer at a first temperature in the presence of an initiator;
And a second polymerizing while being warmed to a second temperature lower than the first temperature; And
And third polymerizing at the second temperature,
Wherein during the first polymerization or the second polymerization, the introduction of the second vinyl chloride monomer is started, but before the elapse of 70 minutes from the start of the first polymerization, the vinyl chloride-based polymer is charged.
The method according to claim 1,
And the second temperature is 2 to 6 ° C lower than the first temperature.
The method according to claim 1,
Wherein the first temperature is from 58 to 62 ° C.
The method according to claim 1,
Wherein the second vinyl chloride monomer is charged after 30 minutes and 70 minutes before the first polymerization is started.
The method according to claim 1,
Wherein the second vinyl chloride monomer is continuously charged from the start of charging to at least two polymerization reactions during the first polymerization to the third polymerization.
The method according to claim 1,
Wherein the second vinyl chloride monomer is charged in an amount of 8 to 13 parts by weight based on 100 parts by weight of the first vinyl chloride monomer.
The method according to claim 1,
Wherein the second polymerization is initiated after the first polymerization is performed for 30 to 70 minutes.
The method according to claim 1,
And the second polymerization is carried out for 20 to 60 minutes.
The method of claim 5,
Wherein the second vinyl chloride monomer is continuously charged for 30 to 60 minutes from the start of charging.
The method according to claim 1,
Wherein the first to third polymerizations are carried out in one reactor.
The method according to claim 1,
Wherein the first to third polymerization are suspension polymerization.
As the suspension-polymerized vinyl chloride polymer, the vinyl chloride-
A degree of polymerization of 980 or more, and an average particle diameter of more than 140 占 퐉.
The method of claim 12,
Wherein the polymerization degree is from 980 to 1,100, and the average particle diameter is from 140 to 170 占 퐉.
The method of claim 12,
Wherein the vinyl chloride-based polymer has a plasticizer absorption rate of 15 to 18%.