JP3238500B2 - Suspension polymerization of vinyl chloride monomer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a suspension polymerization method for a vinyl chloride monomer, and more particularly, it is possible to obtain a polymer having normal particles even when a reflux condenser is operated from the initial stage of polymerization. The present invention relates to a method of suspension polymerization of a vinyl chloride-based monomer with high productivity, which makes it possible to employ a polymerization vessel and shorten the polymerization time.

[0002]

2. Description of the Related Art Polymerization of a vinyl chloride monomer is an exothermic reaction, and the ratio of the jacket area to the volume of the polymerization reactor decreases as the size of the polymerization reactor increases (the capacity increases). (Heat removal) becomes difficult. Recently, attempts have been made to shorten the polymerization time by increasing the polymerization initiator concentration in order to improve the productivity, but this has made it increasingly difficult to remove heat using only the polymerization jacket. In order to solve this problem, a heat removal method using a reflux condenser (hereinafter referred to as RC) has come to be used in combination with a heat removal method using a polymerizer jacket. However, when the RC is operated, the particles of the produced polymer become coarse or, in extreme cases, a part of the suspension becomes clumpy and normal particles cannot be obtained. Also, the fish eyes of the polymer particles of the product increase. For this reason, conventionally, RC
The operation must be performed only in the latter half of the polymerization, or at most from a polymerization conversion rate of 5% or more (Japanese Patent Publication No. 53-53).
-38311, JP-A-54-38391). However, if the polymerization vessel is made large or the polymerization time is shortened, it becomes impossible to remove heat only by the polymerization vessel jacket when the polymerization conversion is between 0 and 5%. From this point of view, it has been desired to develop a technique for using RC that can provide normal polymer particles even when RC is operated from the beginning of polymerization and that does not increase fish eyes.

[0003]

SUMMARY OF THE INVENTION The present invention relates to a suspension polymerization method of a vinyl chloride-based monomer capable of operating RC from the beginning of polymerization and obtaining a product of good quality. That is, an object of the present invention is to provide a suspension polymerization method of a vinyl chloride-based monomer which can easily remove heat by RC even if a large-sized polymerization vessel is used or the polymerization time is shortened, and a good product can be obtained.

[0004]

Means for Solving the Problems When the RC is operated from the initial stage of polymerization, the particles of the produced polymer become coarse because the reflux and the disturbance of the monomer occur rapidly by the operation of the RC. Is destroyed. The present invention
An object of the present invention is to provide a method for producing a vinyl chloride monomer which solves the above problems. That is, a first aspect of the present invention is to disperse an aqueous medium, a vinyl chloride-based monomer, and a dispersant comprising polyethylene oxide having an average molecular weight of 100,000 to 4.8 million in a polymerization vessel equipped with an RC. 0.0005 to 0.05 parts by weight, based on 100 parts by weight, of a dispersant used together with 0.1 part by weight.
03-1.5 parts by weight and a polymerization initiator are charged and the temperature is increased. The temperature in the polymerization vessel reaches a predetermined polymerization temperature and RC is operated. In the polymerization method of the present invention, a dispersant comprising an aqueous medium, a vinyl chloride-based monomer, and polyethylene oxide having an average molecular weight of 100,000 to 4.8 million is added to a polymerization vessel equipped with RC. 0.0 to 100 parts by weight of monomer
005 to 0.05 parts by weight, and the dispersant to be used in combination is 0.03 to
After adding 1.5 parts by weight and raising the temperature, after the temperature in the polymerization vessel reaches a predetermined polymerization temperature, the polymerization initiator is charged and the RC is operated. The polymerization method shall be the content.

Hereinafter, the present invention will be described in detail. In the present invention, all of the polymerization calorific value may be removed by RC.
The heat may be removed from both the heat exchanger and the polymerizer jacket. The control of heat removal in the RC can be performed by a known method such as water amount adjustment and water temperature adjustment by operating a valve. The control of heat removal in the jacket of the polymerization reactor can be performed by the same known method. In the present invention, before charging the aqueous medium and the like in the polymerization vessel,
It is preferable to degas the inside of the polymerization vessel and the RC in advance from the viewpoint of product quality. Furthermore, it is preferable to use ion-exchanged water which has been degassed and heated in advance, or a vinyl chloride monomer which has been heated in advance, from the viewpoint of improving productivity.

In the present invention, the vinyl chloride monomer is vinyl chloride alone or a mixture of vinyl chloride as a main component (80% by weight or more) and another monomer copolymerizable with vinyl chloride. . Examples of other monomers referred to herein include vinyl acetate, acrylate, ethylene, propylene, butene, allyl chloride, vinylidene chloride, and the like, and these may be used alone or in combination of two or more.

The average molecular weight of polyethylene oxide, which is one type of dispersant used in the present invention, is from 100,000 to 4.8 million, preferably from 1.7 to 4.8 million. If the average molecular weight is less than 100,000, the effect of preventing the coarsening of the particles is not seen,
If it exceeds 4.8 million, although the particles have a stabilizing effect, the fish eyes of the product increase, and a product of good quality cannot be obtained.

The amount of polyethylene oxide added is 0.0005 to 0.0 with respect to 100 parts by weight of the vinyl chloride monomer.
5 parts by weight, preferably 0.005 to 0.01 parts by weight. If the addition amount is less than 0.0005 parts by weight, coarsening of the particles cannot be prevented, and if it exceeds 0.05 parts by weight, fish eyes increase, and a product of good quality cannot be obtained.

The dispersant used in combination with polyethylene oxide in the present invention may be any dispersant used for the polymerization of vinyl chloride monomers. For example, methylcellulose, hydroxyethylcellulose, water-soluble cellulose such as hydroxypropylcellulose, partially saponified polyvinyl acetate, polyvinylpyrrolidone, water-soluble polymer such as maleic anhydride / vinyl ether copolymer, ethylene oxide propylene oxide block polymer, sorbitan monolaurate,
There are water-soluble compounds such as sorbitan trioleate, polyoxyethylene lauryl ether and polyoxyethylene phenyl ether. The amount used is vinyl chloride monomer 10
0.03 to 1.5 parts by weight with respect to 0 parts by weight.

The polymerization initiator used in the present invention may be any polymerization initiator used for the polymerization of vinyl chloride monomers.
For example, diisopropyl peroxydicarbonate, s
-Butylperoxydicarbonate, di-2-ethylhexylperoxydicarbonate, ethoxyethylperoxydicarbonate, t-butylperoxyneodecanate, α-cumylperoxyneodecanate, 3,
Peroxides such as 5,5-trimethylhexanoyl peroxide, azobis-2,4-dimethylvaleronitrile,
Azo compounds such as azobis (4-methoxy-2,4-dimethyl) valeronitrile;
Used in combination of more than one species. The amount used is 0.03 to 1.5 parts by weight based on 100 parts by weight of the vinyl chloride monomer. In the present invention, known chain transfer agents, pH regulators, various additives and the like appropriately used for the polymerization of vinyl chloride monomers can be used as necessary. The polymerization temperature is 40 to 8
0 ° C is good.

[0011]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, which do not limit the present invention in any way. In the following Tables 1 to 4, fish eyes were measured by the following method. 50 parts by weight of a plasticizer (DOP), 2.0 parts by weight of dibutyltin maleate, 0.5 parts by weight of ethylene glycol monostearate, 0.5 parts by weight of titanium oxide, and carbon black based on 100 parts by weight of the produced polymer Add 0.1 parts by weight and blend,
This is kneaded with an 8-inch roll at 145 ° C. for 5 minutes, and then a 0.3 mm sheet is taken out. This sheet 100cm
The number of transparent eyes per ² is counted as the number of fish eyes. After degassing the inside of the inner volume of 1.5 m ³ polymerization reactor equipped with Example 1 to 4 RC with internal RC, ion-exchanged water was degassed, vinyl chloride, an average molecular weight as a dispersant is 3.5 million polyethylene oxide (Trade name: PEO15: manufactured by Iron and Steel Chemical Industry Co., Ltd.) and partially saponified polyvinyl acetate [saponification degree: 78.5 to 8]
1.5 mol%, 4% viscosity (20 DEG C.), 32 to 38 mPas] to 0.006 parts by weight and 0.06 parts by weight with respect to 100 parts by weight of vinyl chloride, and di-2-ethylhexyl peroxy as a polymerization initiator. 0.03 parts by weight of dicarbonate and 100 parts by weight of t-butylperoxyneodecanate were charged to each vinyl chloride, and the temperature in the polymerization vessel was adjusted to 57%.
The temperature was raised to ° C. The RC was operated at the same time when the temperature in the polymerization reactor reached 57 ° C. The polymerization was carried out for 4 hours and the polymerization conversion was 8
2%. During the polymerization, the cooling water temperature of the RC and the temperature of the polymerization reactor jacket were controlled, and the heat of the polymerization reaction was removed by the RC and the polymerization reactor jacket. The total charge of ion exchange water and vinyl chloride was 1200 kg, and the weight ratio of ion exchange water and vinyl chloride was 1.2 / 1.0. Table 1 shows the results.

Comparative Examples 1 to 3 Polymerization was carried out in the same manner as in Examples except that polyethylene oxide was not used as a dispersant. Table 1 shows the results.

Example 5 Ion-exchanged water, vinyl chloride, polyethylene oxide (trade name: PEO15, manufactured by Seikagaku Corporation) and partially saponified polyvinyl acetate [saponification degree: 78.5 to 81.5 mol%, 4
% Viscosity (20 ° C.) 32-38 mPas], and the temperature in the polymerization vessel was raised to 57 ° C., and then di-2-ethylhexylperoxydicarbonate and t-butylperoxyneodecanate were charged. The RC was activated.
Except for this, polymerization was carried out in the same manner as in Examples 1 to 4. Table 1 shows the results.

Reference Example 1 Polymerization was carried out in the same manner as in the Example except that polyethylene oxide was not used as a dispersant and the heat of the polymerization reaction was removed only by the jacket of the polymerization vessel. Table 1 shows the results.

[0015]

[Table 1]

Examples 6 to 9, Comparative Examples 4 and 5 The interior of a 1.5 m ³ polymerization vessel equipped with RC was degassed together with the interior of RC, and degassed ion-exchanged water, vinyl chloride,
As dispersants, polyethylene oxide and partially saponified polyvinyl acetate having different average molecular weights [saponification degree 78.5 to 81.
5 mol%, 4% viscosity (20 DEG C.) 44 to 52 mPas] to 0.006 parts by weight and 0.06 parts by weight with respect to 100 parts by weight of vinyl chloride, and 3,5,5-
0.04 parts by weight and 0.022 parts by weight of trimethylhexanoyl peroxide and t-butyl peroxyneodecanate were added to 100 parts by weight of vinyl chloride, respectively, and the temperature in the polymerization vessel was raised to 67 ° C. The RC was activated at the same time when the temperature in the polymerization reactor reached 67 ° C. Polymerization 3
Time was 30 minutes. The polymerization conversion was 75%. During the polymerization, the cooling water temperature of the RC and the temperature of the polymerization reactor jacket were controlled, and the heat of the polymerization reaction was removed by the RC and the polymerization reactor jacket.
The total charge of ion-exchanged water and vinyl chloride was 120
0 kg, the weight ratio of ion-exchanged water to vinyl chloride is 1.2 /
1.0. Table 2 shows the results.

Comparative Example 6 Polymerization was carried out in the same manner as in Examples 6 to 9 except that polyethylene oxide was not used as a dispersant. Table 2 shows the results.

[0018]

[Table 2]

Examples 10 to 13 and Comparative Examples 7 and 8 Example 1 was repeated except that polyethylene oxide having an average molecular weight of 1.7 million (trade name: PEO8: manufactured by Iron and Steel Chemical Industry Co., Ltd.) was used and the amount used was changed. Polymerization was carried out in the same manner as in 6-9. Table 3 shows the results.

[0020]

[Table 3]

Example 14 The inside of a 70 m ³ polymerization vessel equipped with RC was degassed together with the inside of RC, degassed ion-exchanged water, vinyl chloride, and polyethylene oxide having an average molecular weight of 4.8 million as a dispersant (commercially available) PEO18: manufactured by Iron and Steel Chemical Industry Co., Ltd.) and partially saponified polyvinyl acetate [saponification degree 78.5 to 81.5 mo
1%, 4% viscosity (20 ° C.) of 44 to 52 mPas] were added to 0.008 parts by weight and 0.08 parts by weight, respectively, based on 100 parts by weight of vinyl chloride.
6 parts by weight, and 0.04 parts by weight and 0.022 parts by weight of 3,5,5-trimethylhexanoyl peroxide and t-butylperoxyneodecanate as polymerization initiators with respect to 100 parts by weight of vinyl chloride, respectively. The temperature in the polymerization reactor was increased to 67 ° C. The RC was activated at the same time when the temperature in the polymerization reactor reached 67 ° C. Polymerization for 3 hours 30
Minutes went. The polymerization conversion was 75%. During the polymerization, the cooling water temperature of the RC and the temperature of the polymerization reactor jacket were controlled, and the heat of the polymerization reaction was removed by the RC and the polymerization reactor jacket. The total charge of ion-exchanged water and vinyl chloride was 54000 kg, and the weight ratio of ion-exchanged water to vinyl chloride was 1.2 / 1.0. Table 4 shows the results.

Comparative Example 9 Polymerization was carried out in the same manner as in Example 14 except that polyethylene oxide was not used as a dispersant. Table 4 shows the results.

Example 15 Ion-exchanged water, vinyl chloride, polyethylene oxide (trade name: PEO18, manufactured by Seikagaku Corporation) and partially saponified polyvinyl acetate [saponification degree: 78.5 to 81.5 mol%, 4
% Viscosity (20 ° C.) of 44 to 52 mPas], the temperature in the polymerization vessel was raised to 67 ° C., and then 3,5,5-trimethylhexanoyl peroxide and t-butylperoxyneodecanate were charged. The RC was activated. Except for this, polymerization was carried out in the same manner as in Example 14. Table 4 shows the results.

[0024]

[Table 4]

As shown in Tables 1 to 3, when an aqueous medium, vinyl chloride, a conventional dispersant, and a polymerization initiator were charged and the temperature was raised, the RC was activated at the same time when the temperature in the polymerization reactor reached a predetermined polymerization temperature. The resulting polymer particles become coarse, or a part of the suspension becomes clumpy and a good product cannot be obtained, and the fisheye is poor.On the other hand, when polyethylene oxide is used in combination with the above polymerization method according to the present invention, It can be seen that coarsening of the polymer particles can be avoided and a good product can be obtained.
Further, when the polymerization initiator is charged after the temperature in the polymerization reactor reaches a predetermined polymerization temperature and the RC is operated at the same time, it is understood that the effect is further improved. Also, from Table 4, it can be seen that a good product can be obtained according to the method of the present invention even when the polymerization is carried out in a short time with a large polymerization vessel.

[0026]

As described above, according to the present invention, even if a large polymerization vessel is used or the polymerization reaction speed is increased to shorten the polymerization time, the RC can be operated from the initial stage of the polymerization. Removal is easy and its industrial value is extremely high.

Claims (4)

(57) [Claims] 1. A polymerization vessel equipped with a reflux condenser is charged with an aqueous medium, a vinyl chloride monomer and an average molecular weight of 1
A dispersant composed of polyethylene oxide having a molecular weight of from 100,000 to 4.8 million is added in an amount of 0.00 to 100 parts by weight of the vinyl chloride monomer.
0.05 to 0.05 parts by weight, and a dispersant to be used in combination with 0.03 to
1.5 parts by weight and a polymerization initiator are charged and the temperature is raised. The temperature in the polymerization vessel reaches a predetermined polymerization temperature, and the reflux condenser is operated. Polymerization method. 2. A dispersant comprising an aqueous medium, a vinyl chloride-based monomer, and polyethylene oxide having an average molecular weight of 100,000 to 4.8 million is added to a polymerization vessel equipped with a reflux condenser. 0 parts by weight.
0005-0.05 parts by weight, 0.03
１．５1.5 parts by weight, and the temperature is raised. After the temperature in the polymerization vessel reaches a predetermined polymerization temperature, a polymerization initiator is charged and a reflux condenser is operated. Suspension polymerization method. 3. The polyethylene oxide having an average molecular weight of 1
The suspension polymerization method according to claim 1 or 2, wherein the amount is from 700,000 to 4.8 million. 4. The suspension polymerization method according to claim 1, wherein the amount of the polyethylene oxide is 0.005 to 0.01 parts by weight based on 100 parts by weight of the vinyl chloride monomer.