JP2000063432A - Preparation of vinyl chloride-based polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress foaming of a suspension during polymerization thereby improving operability, to enhance plasticizer absorption thereby decreasing fish-eyes in a product and to lower foamability of a vinyl chloride-based polymer slurry after polymerization thereby reducing the time required for removing an unreacted vinyl chloride-based monomer. SOLUTION: In suspension polymerizing a vinyl chloride-based monomer in the presence of a polymerization initiator and a dispersion stabilizer in an aqueous medium in not more than 6 hr polymerization time using a large-sized polymerization reactor having an inner volume of at least 100 m3 equipped with a reflux condenser, 0.01-0.2 pts.wt., based on 100 pts.wt. of the vinyl chloride-based monomer, of a polyethylene oxide having an average mol.wt. of 10,000-6,000,000 is added while the polymerization conversion rate is between 60% and 80%.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a vinyl chloride-based polymer, and more specifically, it removes heat from a reflux condenser by adding polyethylene oxide at a specific polymerization conversion rate. Produces a vinyl chloride-based polymer that is porous and has excellent plasticizer absorbability and less fish eyes when molded without causing deterioration in quality and operational problems due to foaming during polymerization even in a production method involving It is about the method.

[0002]

2. Description of the Related Art Various studies have heretofore been made on the technique of using polyethylene oxide for the polymerization of vinyl chloride-based monomers.

JP-A-9-302003 discloses a method in which polyethylene oxide is additionally added at the same time as the vinyl chloride-based monomer for the purpose of preventing defective stirring when additional charging of the vinyl chloride monomer is carried out. A method for polymerizing vinyl monomers is disclosed. The additional charging of vinyl chloride monomer is effective for improving the productivity, but brings about an increase in the viscosity of the polymerization system. This is because in the latter half of the polymerization, the viscosity of the polymerization system increases due to the gel effect, and the ratio of the aqueous medium / monomer decreases due to the addition of the monomer, so that the viscosity increases. If such a thickening phenomenon occurs, the heat of the polymerization reaction cannot be sufficiently removed because the stirring effect decreases. On the other hand, in the polymerization method described in the above publication, poor stirring is suppressed by additionally adding polyethylene oxide as a dispersion stabilizer together with the vinyl chloride-based monomer. That is, it solves the inherent problem that occurs when the vinyl chloride-based monomer is additionally added during the polymerization. In addition, when the polyethylene oxide is additionally added, the polymerization conversion rate is 20%, 3
An example in which 0% and 40% are used is shown.

Japanese Patent Laid-Open No. 6-136010 discloses a polymerization method in which a predetermined amount of polyethylene oxide is charged in a polymerization vessel equipped with a reflux condenser, the temperature is raised, and then the reflux condenser is operated. . As a result, the reflux condenser can be operated from the initial stage of the polymerization, so that the heat of the polymerization reaction can be easily removed.

[0005]

[Problems to be Solved by the Invention] By the way, in recent years
There is a strong demand for improvement in production efficiency, and the internal volume is 100m.
³Suspension within a short time within 6 hours using the above large-scale polymerization vessel
It is desired to complete the polymerization. Such a harsh
Under extreme polymerization conditions, significant foaming occurs during polymerization, which
Due to being recognized under conventional mild reaction conditions
A new problem that did not exist occurs. That is, during polymerization
Adhesion and blockage of polymer on reflux condenser by foaming, plasticizer
In operation, such as decreased absorbency and increased product fisheye,
Quality problems occur. Such problems are especially caused by reflux condensation
When heat is removed with a vessel, foaming in the polymerization system increases.
It becomes even more remarkable.

Further, when a large-scale polymerization vessel having an internal volume of 100 m ³ or more is used, since the vinyl chloride polymer slurry after polymerization has a high foaming property, when the unreacted vinyl chloride monomer is removed, foaming occurs. It is easy to happen. Therefore, there is a problem that it takes a long time to remove the unreacted vinyl chloride-based monomer and the productivity is reduced.

Further, in order to solve the above-mentioned quality problems such as a decrease in plasticizer absorption and an increase in product fish eyes, a dispersion stabilizer having a polymerization degree of 300 to 1000 and a saponification degree of 65 to 75 mol% is used. When partially saponified polyvinyl alcohol is used in combination, or when a large amount of partially saponified polyvinyl alcohol having a degree of polymerization of 100 to 700 and a degree of saponification of 20 to 55 mol% is used, not only foaming during polymerization but also chlorination after polymerization is performed. The foamability of the vinyl polymer slurry also becomes high. Therefore, foaming tends to occur when the unreacted vinyl chloride-based monomer is removed, and it takes a long time to remove the unreacted vinyl chloride-based monomer, resulting in a problem that productivity is reduced.

Further, under severe polymerization conditions such that the amount of heat removed by the reflux condenser is 30% or more with respect to the total amount of heat removed, the above problems become more remarkable and the bulk specific gravity decreases. A new quality problem occurs.

As described above, when a vinyl chloride-based monomer is polymerized under severe conditions, there are unique problems that conventional polymerization does not have. However, the above-mentioned prior art does not teach any solution to such a problem.

For example, the technique disclosed in Japanese Patent Application Laid-Open No. 9-302003 proposes a method for preventing a decrease in the water / monomer ratio due to the additional addition of the monomer and an increase in the viscosity of the polymerization system due to the gel effect. However, there is no description or suggestion of means for suppressing foaming during polymerization under the above-mentioned severe polymerization conditions and foaming when removing unreacted vinyl chloride-based monomer. Addition of a large amount of vinyl chloride-based monomer during the polymerization complicates the operation and may cause quality fluctuation. For this reason, in recent years, rather than additional addition of the monomer, rather than the additional addition of the monomer, the batch charging of the system monomer at the beginning using a large-scale polymerization vessel, the method of producing a large amount of polymer by a simple operation is the mainstream Has become. Regarding the problem specific to such a manufacturing method, the technique described in the above publication does not provide any solution.

Further, Japanese Patent Laid-Open No. 6-136010 discloses that
By initially charging polyethylene oxide,
This makes it possible to use the reflux condenser from the beginning. Since polyethylene oxide is initially charged, no improvement effect can be obtained with respect to foaming in the latter half of polymerization or foaming when removing unreacted vinyl chloride-based monomer.

It is an object of the present invention to solve these problems, suppress foaming of a suspension during polymerization, improve operability, enhance absorbability of a plasticizer, and reduce product fish eyes. . Further, another object is to reduce the foamability of the vinyl chloride polymer slurry after polymerization and shorten the removal time of unreacted vinyl chloride monomer.

[0013]

Means for Solving the Problems As a result of intensive studies on the above problems, the present inventors have found that the above problems can be solved by adding a specific amount of polyethylene oxide having a specific molecular weight at a specific time. The present invention has been completed.

According to the present invention, a vinyl chloride monomer is used in an aqueous medium in the presence of a polymerization initiator and a dispersion stabilizer by using a large-sized polymerization vessel having an internal volume of 100 m ³ or more, which is equipped with a reflux condenser. When the suspension polymerization is carried out with the polymerization time being within 6 hours, polyethylene oxide having an average molecular weight of 10,000 to 6,000,000 is added to 100 parts by weight of the vinyl chloride-based monomer while the polymerization conversion rate is 60 to 80%. There is provided a method for producing a vinyl chloride-based polymer, which comprises adding 0.01 to 0.2 part by weight.

Further, according to the present invention, in the above method for producing a vinyl chloride polymer, the dispersion stabilizer (A) is a partially saponified polyvinyl having a polymerization degree of 2000 to 3000 and a saponification degree of 75 to 85 mol%. Alcohol, and / or (B) the degree of polymerization is 300 to 1000 and the degree of saponification is 65.
-75 mol% of partially saponified polyvinyl alcohol is added to a total of 0.0 parts by weight based on 100 parts by weight of the vinyl chloride-based monomer.
3 to 0.15 parts by weight, and (C) the degree of polymerization is 1
A partially saponified polyvinyl alcohol having a saponification degree of 20 to 55 mol% and a vinyl chloride monomer 100
There is provided a method for producing a vinyl chloride polymer, which comprises using 0.01 to 0.1 part by weight with respect to parts by weight.

According to the present invention, in the above-mentioned method for producing a vinyl chloride polymer, the amount of heat removed by the reflux condenser during polymerization is 30% or more of the total amount of heat removed. Provided is a method for producing a polymer.

[0017]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the polymerization conversion rate is 60 to 80% when polyethylene oxide is added.
%, Preferably between 60 and 70%. That is,
The addition start time is set to a time when the polymerization conversion rate is 60% or more, and the addition end time is set to a time when the polymerization conversion rate is 80% or less, preferably 70% or less. By performing the addition at such a time, it is possible to suppress the foaming of the suspension, improve the operability, enhance the absorbability of the plasticizer, and reduce the product fish eye. Furthermore, since the foamability of the vinyl chloride polymer slurry after polymerization can be lowered, foaming at the time of removing the unreacted vinyl chloride monomer can be suppressed. As a result, the removal time of the unreacted vinyl chloride-based monomer can be shortened, and the productivity can be improved. When the addition is started at a polymerization conversion rate of less than 60%, the foaming of the suspension cannot be sufficiently suppressed, and the plasticizer absorbability and the product fisheye improving effect cannot be sufficiently obtained. In particular, the effect of suppressing the foamability of the vinyl chloride polymer slurry after polymerization cannot be sufficiently obtained. When the addition start time is over 80% of the polymerization conversion rate, the foaming of the suspension during the polymerization cannot be sufficiently suppressed, and the plasticizer absorbability and the product fisheye improving effect can be sufficiently obtained. Absent. Similarly, if the addition end time is outside the range of 60 to 80%, the above effect cannot be obtained.

In the present invention, the method of adding polyethylene oxide is not particularly limited, and the polymerization conversion rate is 60.
If it is between -80%, the total amount of polyethylene oxide may be added all at once, or may be added in several divided portions.
Moreover, you may add continuously over a certain period.

In the present invention, the polymerization conversion rate is 60-80.
The average molecular weight of polyethylene oxide added in the range of 10% is 10,000 to 6,000,000.

When the average molecular weight of polyethylene oxide is 10,000 or more, the effect of preventing foaming is sufficient, the foaming during polymerization is small, and the deterioration of quality and problems in operation do not occur. In addition, when the average molecular weight of polyethylene oxide is 6,000,000 or less, the added polyethylene oxide itself does not cause foaming, foaming hardly occurs during polymerization, and not only deterioration of quality and problems in operation do not occur.
The foamability of the vinyl chloride polymer slurry after polymerization is also low,
Since foaming does not easily occur when removing the unreacted vinyl chloride-based monomer, it takes no time to remove the unreacted vinyl chloride-based monomer, and as a result, the productivity does not decrease.

The amount of polyethylene oxide used is 0.01 to 0.2 part by weight, particularly preferably 0.03 to 0.15 part by weight, based on 100 parts by weight of the vinyl chloride monomer.

The amount of polyethylene oxide used is 0.0
When the amount is less than 1 part by weight, the effect of preventing foaming is insufficient, and foaming is small during polymerization, which may cause deterioration of quality and operational problems. If the amount of polyethylene oxide used is more than 0.2 parts by weight, the added polyethylene oxide itself causes foaming, which may cause foaming during polymerization, resulting in deterioration of quality and operational problems. Furthermore, the foamability of the vinyl chloride polymer slurry after polymerization becomes high, and foaming occurs when removing the unreacted vinyl chloride monomer, and it takes a long time to remove the unreacted vinyl chloride monomer. Productivity may decrease.

As described above, according to the present invention, the foaming phenomenon at the final stage of polymerization can be effectively suppressed. Therefore, the range of selection of the dispersion stabilizer to be used in combination can be expanded. For example, while having the effect of improving the plasticizer absorbency and the product fish eye, since the foaming is remarkable, it is possible to use a dispersion stabilizer which was difficult to use in the conventional polymerization method.

In the method for producing a vinyl chloride-based monomer of the present invention, the dispersion stabilizer (A) has a degree of polymerization of 2000 to 30.
00 and partially saponified polyvinyl alcohol having a saponification degree of 75 to 85 mol%, and / or (B) the degree of polymerization is 30.
A partially saponified polyvinyl alcohol having a saponification degree of 0 to 1000 and a saponification degree of 65 to 75 mol% is used in a total amount of 0.03 to 0.15 parts by weight based on 100 parts by weight of the vinyl chloride-based monomer, and further, ( C) The partially saponified polyvinyl alcohol having a degree of polymerization of 100 to 700 and a degree of saponification of 20 to 55 mol% is 0.0 with respect to 100 parts by weight of the vinyl chloride-based monomer.
It is preferable to use 1 to 0.1 parts by weight. By using such a dispersion stabilizer, it is possible to further improve the porosity and the plasticizer absorbability of the vinyl chloride polymer and further reduce the fish eyes when molded.

Here, the partially saponified polyvinyl alcohol (B) preferably has a mercapto group at at least one end of the molecular chain. The partially saponified polyvinyl alcohol (C) is preferably used as a dispersion liquid in which water is finely dispersed with a particle size of 1 μm or less. By doing so, the effect of improving the porosity of the vinyl chloride-based polymer, the absorbability of the plasticizer, and the effect of reducing the product fish eye become more remarkable.

The polymerization initiator used in the present invention may be one generally used as a polymerization initiator in the suspension polymerization method, and examples thereof include diisopropyl peroxydicarbonate, tert-butyl peroxyneodecanate and tert-. Peroxides such as hexyl peroxypivalate and benzoyl peroxide; azo compounds such as 2,2′-azobisisobutyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile and the like;
These can be used alone or in combination of two or more. The amount of the polymerization initiator used is 100 parts by weight of the vinyl chloride-based monomer, since high-speed polymerization is possible.
It is desirable to use 0.05 to 0.02 parts by weight.

According to the polymerization method of the present invention, even when the polymerization time is 6 hours or less, more preferably 4 hours or less, porosity can be obtained without causing quality deterioration due to foaming during the polymerization and operational problems. It is characterized in that it is possible to produce a vinyl chloride polymer having excellent plasticizer absorbency and less fish eyes when molded.

According to the method for producing a vinyl chloride polymer of the present invention, a large reactor of 100 m ³ or more, and further 120
Even if a large reactor of m ³ or more is used, a high-quality vinyl chloride polymer can be produced without the above-mentioned operational problems.

The polymerization time in the present invention is defined as the time when the polymerization raw materials are charged, the temperature is raised, and the internal temperature reaches a predetermined temperature.
The time until the pressure in the polymerization vessel dropped 1.8 kg / cm ² from the initial pressure was defined as the polymerization time. Even if the polymerization method is such that the polymerization is terminated when the decrease in internal pressure is less than 1.8 kg / cm ² , the decrease in internal pressure is within 6 hours when the polymerization is continued under normal conditions. Polymerizations of 1.8 kg / cm ² are within the scope of the invention. Such a polymerization is substantially the same as the polymerization method of the present invention in which the end point of the polymerization is defined as 6 hours or less after being defined as described above. Because it is different.

In the present invention, the stirrer of the polymerization vessel is not particularly limited, and baffles may be used if desired. Examples of the agitator include turbine blades, fan turbine blades, Fowler blades, and blue margin blades that are usually used for polymerization of vinyl chloride-based monomers, and examples of baffles include finger type, cylindrical type, D type, and loop type. It

As the reflux condenser attached to the polymerization vessel used in the polymerization method of the present invention, a known condenser can be used, and the method described in the literature can be applied to the operation method thereof (for example, edited by Saeki and Nagami: New polymer manufacturing process (published by the Industrial Research Board), page 158, Table 6.5).

In a high-speed polymerization in which the polymerization reactor becomes large in size, a reflux condenser is additionally provided, and the polymerization is completed in a short time of about 2.5 to 4 hours, when the heat removal ratio in the reflux condenser is large, it is usually used. Although there is a tendency for fish eye and scale adhesion to increase, the polymerization method of the present invention exhibits a particularly excellent effect in polymerization under such conditions.

Specifically, when the amount of heat removed by the reflux condenser during the polymerization is 30% or more of the total amount of heat removed, a more excellent effect is exhibited, and when it is 40% or more, a particularly excellent effect is exhibited. To do. While the productivity is improved by setting such severe polymerization conditions, the foaming in the latter half of the polymerization and the foaming at the time of collecting unreacted monomers become more remarkable, and fish eyes and scale adhesion increase. However, there arises a quality problem that the bulk specific gravity is reduced. In addition, as a dispersion stabilizer for the purpose of improving fish eyes,
A partially saponified polyvinyl alcohol having a degree of polymerization of 300 to 1000 and a degree of saponification of 65 to 75 mol% is used in combination,
When a large amount of partially saponified polyvinyl alcohol having a degree of polymerization of 100 to 700 and a degree of saponification of 20 to 55 mol% is used, not only foaming during polymerization but also foamability of the vinyl chloride polymer slurry after polymerization is high. Become. Therefore, foaming easily occurs when removing the unreacted vinyl chloride-based monomer, and it takes a long time to remove the unreacted vinyl chloride-based monomer,
There is a problem that productivity is reduced. In contrast,
In the present invention, since polyethylene oxide is added under predetermined conditions to suppress foaming, productivity can be improved while avoiding the above problems.

In the present invention, when carrying out the present invention, a vinyl monomer copolymerizable with a vinyl chloride monomer or a polymer graft-polymerizable with a vinyl chloride monomer is added as required. May be polymerized.

The vinyl chloride type monomer in the present invention means
A vinyl chloride monomer or a mixture of a vinyl chloride monomer and a vinyl-based monomer copolymerizable therewith.

Examples of vinyl monomers copolymerizable with the vinyl chloride monomer include vinyl esters such as vinyl acetate, vinyl propionate, vinyl caproate, vinyl laurate and vinyl stearate; ethylene, propylene, Olefins such as isobutylene; alkyl or aryl vinyl ethers such as isobutyl vinyl ether, phenyl vinyl ether, octyl vinyl ether; halogenated olefins such as vinylidene chloride, vinyl fluoride, allyl chloride, vinyl bromide; ethyl acrylate, n
-Butyl acrylate, n-butyl methacrylate, 2
-Acrylic acid or methacrylic acid esters such as ethylhexyl acrylate, 2-ethylhexyl methacrylate, stearyl methacrylate; acrylic derivatives such as acrylic acid, methacrylic acid, crotonic acid, acrylonitrile, maleic anhydride, and itaconic anhydride. it can.

Examples of the polymer which can be graft-copolymerized with a vinyl chloride monomer include ethylene-vinyl acetate copolymer (EVA), ethylene-ethyl acrylate copolymer, chlorinated polyethylene, polyurethane, polybutadiene-styrene. -Methyl methacrylate copolymer (MB
S), polybutadiene-acrylonitrile- (α-methyl) styrene copolymer (ABS), polybutyl acrylate, butyl rubber, polystyrene, styrene-butadiene copolymer, crosslinked acrylic rubber and the like.

According to the production method of the present invention, even in the production method involving heat removal by a reflux condenser, it is porous and excellent in plasticizer absorbability without causing deterioration in quality and operational problems due to foaming during polymerization. Thus, it is possible to obtain a vinyl chloride polymer having less fish eyes when molded.

The polymerization slurry obtained by the polymerization method of the present invention is sent to a post-treatment step for removing unreacted vinyl chloride monomer. As the post-treatment step, a tank-type or tower-type stripping step is preferably used, and a known method is applied.
(For example: Saeki, Nagami ed .: New polymer manufacturing process (published by the Industrial Research Board), page 163).

[0040]

The present invention will be further described with reference to the following examples, which should not be construed as limiting the present invention.

In the examples and comparative examples, the dispersion stabilizer and polyethylene oxide were added in the vinyl chloride monomer 10 parts.
The number of parts by weight relative to 0 parts by weight is shown. Moreover, the physical properties of the polymers obtained in Examples and Comparative Examples were evaluated by the following methods.

(Average particle diameter) The average particle diameter was defined as the size (μm) of the sieve through which 50% of the obtained vinyl chloride polymer particles passed.

(Amount of absorbed plasticizer) An excessive amount of plasticizer (dioctyl phthalate; DOP) was added to the obtained polymer, and the mixture was allowed to stand at room temperature for 10 minutes and then centrifuged (Domestic Centrifuge Co., Ltd.).
Was used to remove the plasticizer not absorbed by the polymer. The amount of plasticizer retained in the polymer after centrifugation was measured, and the ratio of the plasticizer retained in the polymer to the polymer was expressed as a percentage, which was taken as the plasticizer absorption amount.

(Fish eye) 100 parts by weight of the obtained vinyl chloride polymer, Ca--Zn powder composite stabilizer 1.
5 parts by weight, 0.5 part by weight of an organic phosphorus-based stabilizing aid, 3 parts by weight of ultramarine and 50 parts by weight of DOP (dioctyl phthalate) are mixed, and a roll at 150 ° C. is formed to a thickness of 0.35 mm.
Mix and knead to separate 0.35 mm sheet,
It is shown by the number of transparent particles in cm ² .

Example 1 Pure water 1 was added to a reactor having an internal volume of 120 m ³ having a reflux condenser.
40 parts by weight, saponification degree 80 mol%, partially saponified polyvinyl alcohol having a degree of polymerization of 2600 0.05 parts by weight, saponification degree 40 mol%, partially saponified polyvinyl alcohol having a degree of polymerization of 550 0.08 parts by weight, tert- 0.08 parts by weight of butyl peroxyneodecanate was added and the pressure was reduced.
Next, 100 parts by weight of vinyl chloride monomer was charged, the temperature in the autoclave was raised to 57 ° C. with stirring, cooling water was passed through the reflux condenser, and the heat removal amount by the reflux condenser was 40% of the total polymerization heat value. Polymerization was continued by adjusting so as to be ˜50%. Next, when the conversion of polymerization reached 65%, 0.03 part by weight of polyethylene oxide having an average molecular weight of 500,000 was added. Then, the polymerization was stopped when the pressure in the reactor dropped 1.8 kg / cm ² from the pressure in the steady state of the polymerization reaction. The polymerization time was 3 hours. After the termination of the polymerization, unreacted vinyl chloride monomer was removed from the unreacted monomer recovery line above the reactor with stirring. On this occasion,
The reactor temperature was maintained at 50 ° C. No bubbles were observed in the unreacted monomer recovery line during removal of the unreacted monomer, and the recovery was completed in 40 minutes. Further, there was no trace of bubbling in the reflux condenser and the conduit to the reflux condenser, and no polymer adhesion was observed.

After recovering the unreacted vinyl chloride monomer, the slurry was taken out from the autoclave and dehydrated and dried to obtain a vinyl chloride polymer with a polymerization conversion rate of about 85%.

Table 1 shows the evaluation results of the obtained vinyl chloride polymer.

The obtained vinyl chloride polymer was excellent in plasticizer absorbability and had little fish eyes when molded.

Example 2 Example 1 was repeated except that 0.05 part by weight of polyethylene oxide having an average molecular weight of 70,000 was used in place of 0.03 part by weight of polyethylene oxide having an average molecular weight of 500,000 added at a polymerization conversion rate of 65%. A vinyl chloride polymer was obtained in the same manner as in (2) above with a polymerization conversion rate of about 85%.

Table 1 shows the foaming condition at the time of recovering the unreacted monomer, the presence / absence of adhesion of the polymer to the reflux condenser, and the evaluation results of the obtained vinyl chloride polymer.

No bubbling was observed in the line during recovery of unreacted monomers, no trace of bubbling in the reflux condenser and conduit, and no polymer adhesion was observed.

The obtained vinyl chloride polymer was excellent in plasticizer absorption and had little fish eyes when molded.

Example 3 Polymerization of about 85% was carried out in the same manner as in Example 1 except that polyethylene oxide having an average molecular weight of 4,000,000 was used in place of polyethylene oxide having an average molecular weight of 500,000 added at a polymerization conversion rate of 65%. A vinyl chloride polymer was obtained with a conversion rate.

Table 1 shows the foaming condition at the time of recovering the unreacted monomer, the presence or absence of adhesion of the polymer to the reflux condenser, and the evaluation results of the obtained vinyl chloride polymer.

No bubbling was observed in the line during recovery of unreacted monomers, no trace of bubbling in the reflux condenser and conduit, and no polymer adhesion was observed.

The obtained vinyl chloride polymer had excellent plasticizer absorbability and had little fish eyes when molded.

Example 4 Polymerization conversion of about 85% was carried out in the same manner as in Example 1 except that 0.03 part by weight of polyethylene oxide having an average molecular weight of 500,000 added at a polymerization conversion of 65% was added at a conversion of 75%. A vinyl chloride polymer was obtained at a rate.

Table 2 shows the foaming condition at the time of recovering the unreacted monomer, the presence / absence of adhesion of the polymer to the reflux condenser, and the evaluation results of the obtained vinyl chloride polymer.

No bubbling was observed in the line during recovery of unreacted monomers, no trace of bubbling in the reflux condenser and conduit, and no polymer adhesion was observed.

The obtained vinyl chloride polymer was excellent in plasticizer absorption and had little fish eyes when molded.

Example 5 The procedure of Example 1 was repeated except that the amount of polyethylene oxide having an average molecular weight of 500,000 added at a polymerization conversion rate of 65% was 0.01 part by weight, and the polymerization conversion rate was about 85%. A vinyl chloride polymer was obtained.

Table 2 shows the foaming condition at the time of recovering the unreacted monomer, the presence or absence of the polymer adhering to the reflux condenser, and the evaluation results of the obtained vinyl chloride polymer.

No bubbling was observed in the line during recovery of unreacted monomers, no trace of bubbling in the reflux condenser and conduit, and no polymer adhesion was observed.

The obtained vinyl chloride polymer was excellent in plasticizer absorption and had little fish eyes when molded.

Example 6 The dispersion stabilizer added in Example 1 before the start of polymerization was saponified with a degree of saponification of 80 mol% and a degree of polymerization of 2600 with 0.03 part by weight of a partially saponified polyvinyl alcohol and a degree of saponification of 70 mol%. The same procedure as in Example 1 was performed except that 0.02 parts by weight of partially saponified polyvinyl alcohol having a degree of 700 and 40 mol% of saponification degree and 0.06 parts by weight of partially saponified polyvinyl alcohol having a degree of polymerization of 550 were used, and about 85% was obtained. A vinyl chloride polymer was obtained at a polymerization conversion ratio of.

Table 3 shows the foaming condition at the time of recovering the unreacted monomer, the presence / absence of adhesion of the polymer to the reflux condenser, and the evaluation results of the obtained vinyl chloride polymer.

No bubbling was observed in the line during recovery of unreacted monomer, no trace of bubbling in the reflux condenser and conduit, and no adhesion of polymer was observed.

The vinyl chloride polymer obtained was excellent in plasticizer absorbability, and the fish eyes when molded were slightly increased, but there was no problem.

Example 7 The dispersion stabilizer added in Example 2 before the start of polymerization was saponified to 80 mol%, partially saponified polyvinyl alcohol having a polymerization degree of 2600 (0.03 parts by weight), and saponification degree to 70 mol%. The same procedure as in Example 2 was carried out except that 0.02 part by weight of partially saponified polyvinyl alcohol having a degree of 700 and 40 mol% of saponification degree and 0.06 part by weight of partially saponified polyvinyl alcohol having a degree of polymerization of 550 were used, and about 85% was obtained. A vinyl chloride polymer was obtained at a polymerization conversion ratio of.

Table 3 shows the foaming condition at the time of recovering the unreacted monomer, the presence or absence of the polymer adhering to the reflux condenser, and the evaluation results of the obtained vinyl chloride polymer.

No bubbling was observed in the line during recovery of the unreacted monomer, no trace of bubbling was observed in the reflux condenser and the conduit, and no polymer adhesion was observed.

The obtained vinyl chloride polymer was excellent in plasticizer absorbability, and the fish eyes when molded were slightly increased, but there was no problem.

Example 8 The dispersion stabilizer added in Example 3 before the start of polymerization was prepared by adding 80% by mol of saponification, 0.03 part by weight of partially saponified polyvinyl alcohol having a degree of polymerization of 2600, and 70% by mol of saponification. The same procedure as in Example 3 was carried out except that 0.02 part by weight of a partially saponified polyvinyl alcohol having a degree of 700 and 40 mol% of a saponification degree and 0.06 part by weight of a partially saponified polyvinyl alcohol having a degree of polymerization of 550 were used, and about 85% was obtained. A vinyl chloride polymer was obtained at a polymerization conversion ratio of.

Table 3 shows the foaming condition at the time of recovering the unreacted monomer, the presence / absence of adhesion of the polymer to the reflux condenser, and the evaluation results of the obtained vinyl chloride polymer.

No bubbling was observed in the line during recovery of unreacted monomers, no trace of bubbling in the reflux condenser and conduit, and no polymer adhesion was observed.

The obtained vinyl chloride polymer was excellent in plasticizer absorbability and had little fish eyes when molded.

Comparative Example 1 Polymerization of about 85% was carried out in the same manner as in Example 1 except that 0.03 part by weight of polyethylene oxide having an average molecular weight of 500,000 added at a polymerization conversion rate of 65% was added at a polymerization conversion rate of 40%. A vinyl chloride polymer was obtained with a conversion rate.

Table 4 shows the foaming condition at the time of recovering the unreacted monomer, the presence / absence of adhesion of the polymer to the reflux condenser, and the evaluation results of the obtained vinyl chloride polymer.

At the time of collecting the unreacted monomer, foaming into the line was observed, so that the collection rate was reduced, and it took 86 minutes to collect the unreacted monomer. In addition, the adhesion of the polymer was observed in the reflux condenser and the conduit. The obtained vinyl chloride polymer had low plasticizer absorbability and had many fish eyes when molded.

Comparative Example 2 A vinyl chloride polymer was obtained in the same manner as in Example 1 except that the polyethylene oxide having an average molecular weight of 500,000 added at a polymerization conversion rate of 65% was not added. It was

Table 4 shows the foaming condition at the time of recovering the unreacted monomer, the presence / absence of adhesion of the polymer to the reflux condenser, and the evaluation results of the obtained vinyl chloride polymer.

The obtained vinyl chloride polymer had a high plasticizer absorbability and had little fish eyes when molded, but foaming was observed in the line when unreacted monomers were recovered. When the collection rate was reduced, it took 88 minutes to collect the unreacted monomer. In addition, the adhesion of the polymer was observed in the reflux condenser and the conduit.

Comparative Example 3 Polymerization was carried out in the same manner as in Example 1 except that the amount of polyethylene oxide having an average molecular weight of 500,000 added at a polymerization conversion rate of 65% was 0.3 part by weight, and the polymerization conversion rate was about 85%. A vinyl chloride polymer was obtained.

Table 4 shows the foaming condition at the time of recovering the unreacted monomer, the presence / absence of adhesion of the polymer to the reflux condenser, and the evaluation results of the obtained vinyl chloride polymer.

At the time of recovering the unreacted monomer, foaming into the line was observed, so that the recovery rate was reduced, and it took 119 minutes to recover the unreacted monomer. In addition, the adhesion of the polymer was observed in the reflux condenser and the conduit.

The obtained vinyl chloride polymer had a low plasticizer absorbability and a large amount of fish eyes when molded.

Comparative Example 4 Polymerization of about 85% was carried out in the same manner as in Example 6 except that 0.03 part by weight of polyethylene oxide having an average molecular weight of 500,000 added at a polymerization conversion rate of 65% was added at a polymerization conversion rate of 40%. A vinyl chloride polymer was obtained with a conversion rate.

Table 5 shows the foaming condition at the time of recovering the unreacted monomer, the presence / absence of adhesion of the polymer to the reflux condenser, and the evaluation results of the obtained vinyl chloride polymer.

At the time of recovering the unreacted monomer, foaming was observed in the line, so that the recovery rate was reduced and it took 102 minutes to recover the unreacted monomer. In addition, the adhesion of the polymer was observed in the reflux condenser and the conduit. The obtained vinyl chloride polymer had low plasticizer absorbability and had many fish eyes when molded.

Comparative Example 5 A vinyl chloride polymer was obtained in the same manner as in Example 6 except that the polyethylene oxide having an average molecular weight of 500,000 added at a polymerization conversion rate of 65% was not added. It was

Table 5 shows the foaming condition at the time of recovering the unreacted monomer, the presence / absence of adhesion of the polymer to the reflux condenser, and the evaluation results of the obtained vinyl chloride polymer.

The obtained vinyl chloride polymer had a high plasticizer absorbability and a small fish eye when molded, but foaming was observed in the line when the unreacted monomer was recovered. Therefore, when the collection rate was reduced, it took 105 minutes to collect the unreacted monomer. In addition, the adhesion of the polymer was observed in the reflux condenser and the conduit.

The obtained vinyl chloride polymer had a high plasticizer absorbability, but had a large particle size and many fish eyes when molded.

[0094]

[Table 1]

[0095]

[Table 2]

[0096]

[Table 3]

[0097]

[Table 4]

[0098]

[Table 5]

[0099]

EFFECTS OF THE INVENTION According to the production method of the present invention, even in the production method involving heat removal by a reflux condenser, it does not cause quality deterioration and operation problems due to foaming during polymerization, and it has porosity and plasticizer absorbability. It is possible to produce a vinyl chloride polymer which is excellent and has less fish eyes when molded.
Therefore, the present invention has a very high industrial value.

Claims (3)

[Claims] 1. An internal volume of 100 m ³ equipped with a reflux condenser.
When the vinyl chloride monomer is subjected to suspension polymerization in the presence of a polymerization initiator and a dispersion stabilizer in an aqueous medium with a polymerization time of 6 hours or less using the above-mentioned large-scale polymerization reactor, the polymerization conversion rate is 60 to During 80%, polyethylene oxide having an average molecular weight of 10,000 to 6,000,000 was added to vinyl chloride monomer 10
A method for producing a vinyl chloride polymer, which comprises adding 0.01 to 0.2 part by weight to 0 part by weight. 2. As the dispersion stabilizer, (A) a partially saponified polyvinyl alcohol having a polymerization degree of 2000 to 3000 and a saponification degree of 75 to 85 mol%, and / or (B) having a polymerization degree of 300 to 1000. Saponification degree is 65-
75 mol% of partially saponified polyvinyl alcohol is added in a total amount of 0.03 with respect to 100 parts by weight of the vinyl chloride-based monomer.
.About.0.15 parts by weight, and (C) the degree of polymerization is 10
A partially saponified polyvinyl alcohol having a saponification degree of 0 to 700 and a saponification degree of 20 to 55 mol% is used in an amount of 0.01 to 0.1 part by weight based on 100 parts by weight of the vinyl chloride monomer. 1. The method for producing a vinyl chloride polymer according to 1. 3. The method for producing a vinyl chloride polymer according to claim 1, wherein the amount of heat removed by the reflux condenser during polymerization is 30% or more based on the total amount of heat removed.