JPH05239111A - Method for suspension polymerization for vinyl chloride - Google Patents

Abstract

PURPOSE:To extremely shorten a time for heating in polymerization and to polymerize vinyl chloride in high productivity without causing fish eyes and damaging other physical properties by feeding a polymerization initiation under a specific condition in suspension polymerization of vinyl chloride. CONSTITUTION:In suspension polymerization of vinyl chloride, 25-50wt.% deionized water at normal temperature and a suspension agent are based on the total amount of water in the polymerization system fed to an autoclave, then vinyl chloride and a polymerization initiator emulsified and dispersed into an aqueous medium are supplied to the autoclave and stirring is started. Then, 50-80wt.% based on the total amount of water in the polymerization system of deionized water heated to >=the polymerization temperature is added to the autoclave and the temperature in the polymerization system is heated to a given reaction temperature to polymerize vinyl chloride. The amount of deionized water added is 90-200 pts.wt. based on 100 pts.wt. vinyl chloride. A styrene.maleic acid copolymer is used as the suspension agent.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to a suspension polymerization method of vinyl chloride or a monomer mixture containing vinyl chloride as a main component and copolymerizable therewith (hereinafter referred to as vinyl chloride), in which a charging time of a polymerization initiator, The present invention also relates to a suspension polymerization method in which the temperature rising time is shortened to improve the productivity in the polymerization step, and at the same time, the fish eye, the particle size distribution are improved, and scale adhesion is prevented.

[0002]

2. Description of the Related Art Usually, suspension of vinyl chloride is carried out in a batch system. After deionized water, a suspending agent, a polymerization initiator and an additive are charged in an autoclave, the system is degassed to remove vinyl chloride, etc. Is charged, and hot water circulation or steam is passed through the jacket of the autoclave while stirring, and the temperature is raised to the polymerization temperature to start the polymerization reaction. After that, when the heat of polymerization reaction comes out, cooling water is passed through the jacket of the autoclave to keep the polymerization temperature constant, the reaction is continued until a predetermined polymerization rate is reached, and then a monomer gas such as vinyl chloride is added. A series of polymerization operations in which the polymer is recovered and discharged from the autoclave is performed.

[0003]

However, in the above-mentioned conventional methods, the time required for the temperature rising time is one of the causes of the decrease in productivity. Various methods have been considered to solve this problem.

A method in which water, a suspending agent, vinyl chloride and the like heated at a polymerization temperature or higher as described in JP-A-57-5704 and a polymerization initiator are put in an autoclave all at once and the polymerization reaction is immediately started. However, in this method, since vinyl chloride, water, and a suspending agent come into contact with each other near the polymerization temperature, the particle size becomes unstable, and in particular, coarse-grained products increase. In addition, there is a quality defect that fisheyes are significantly increased, which is not a good idea.

Alternatively, a method of charging a suspension agent, a polymerization initiator, other additives and vinyl chloride into an autoclave as disclosed in JP-A-60-47007, and then charging water heated at a polymerization temperature or higher. However, this method produces a scale on the inner wall of the polymerization vessel, and it is difficult to make the polymerization uniform in the initial stage of charging hot water, and coarse particles are generated, resulting in a product with a poor fisheye.

Further, as disclosed in JP-A-54-47785, 3
In the method of charging water at 0 ° C or lower, a suspending agent and a polymerization initiator into an autoclave, then charging vinyl chloride, stirring and mixing, and charging heated water to start polymerization, a considerable scale is generated on the inner wall of the polymerization vessel. However, it has a practical problem.

[0007]

The inventors of the present invention have made intensive studies to solve this drawback and shorten the cycle time of the polymerization step, and as a result, devised a method for charging a polymerization initiator as described above. The drawbacks have been resolved and the present invention has been reached.

That is, according to the present invention, in suspension polymerization of vinyl chloride, first, 20 to 50% by weight of deionized water at room temperature and a suspending agent are charged into an autoclave, and then vinyl chloride and an aqueous solution are added. After charging the polymerization initiator emulsified and dispersed in the medium and starting the stirring, the inside of the polymerization system is charged by charging deionized water heated to a polymerization temperature of 50 to 80% by weight of the total amount of water in the polymerization system. It is intended to provide a suspension polymerization method of vinyl chloride, which is characterized in that the polymerization is carried out by raising the temperature to a predetermined reaction temperature. The present invention will be described in more detail.

The total amount of deionized water used in the present invention is
90-200 parts by weight is preferable with respect to 100 parts by weight of vinyl chloride.

The suspending agents used in the present invention may be any of those known in the art, including styrene-maleic acid copolymers, partially saponified polyvinyl alcohol, methyl cellulose, hydroxypropylmethyl cellulose, ethyl cellulose, gelatin, calcium carbonate. , Calcium phosphate, etc., or a combination of two or more thereof.

The suspending agent is used in an amount of 0.001 to 5 parts by weight based on 100 parts by weight of vinyl chloride. As for the mixing of the suspending agent and water, a stable dispersed state can be obtained by sufficiently mixing at room temperature.

More specifically, it is preferable to carry out the above mixing at a temperature below the cloud point or thermal gelation temperature of the suspending agent used,
Above this temperature, more coarse particles are produced.

As described above, 20 to 50 deionized water at room temperature is used.
After charging the suspending agent to the weight%, the inside of the autoclave is usually subjected to a deaeration treatment to remove the air present in the autoclave. Next, vinyl chloride and a polymerization initiator emulsified and dispersed in an aqueous medium are charged, and after stirring is started, preferably 50 to 80% of the total amount of water in the polymerization system after the stirring reaches a steady state.
By charging deionized water heated to a polymerization temperature of not less than wt%, the temperature in the polymerization system is raised to a predetermined reaction temperature and polymerization is immediately carried out.

The vinyl chloride used in the present invention includes
It is possible to use vinyl chloride or mixtures based on vinyl chloride with monomers copolymerizable therewith. Examples of the component copolymerizable with vinyl chloride include ethylene, vinyl acetate, methyl acrylate, acrylonitrile, and vinylidene chloride.

The polymerization initiator emulsified and dispersed in an aqueous medium is a substance generally used as a polymerization initiator for the polymerization of vinyl chloride, which is emulsified and dispersed in an aqueous medium using an emulsifier and / or a dispersant. Use an emulsified product.

The concentration of this emulsion is not limited, but is preferably 5 to 70% by weight. This is because it is possible to uniformly disperse the polymerization initiator by emulsifying and dispersing the polymerization initiator, and it is possible to achieve stability of particles and reduction of fisheyes. If the concentration is less than 5% by weight, the effect of emulsification and dispersion does not change, and it is not economical. If it exceeds 70% by weight, the effect of emulsification and dispersion may not be sufficiently exhibited.

The aqueous medium used in the present invention is preferably water (deionized water).

The emulsifier used in the present invention may be a nonionic surfactant, such as an ether type alkyl and alkylallyl polyoxyethylene ether, and an ether ester type sorbitan ester polyoxyethylene ether. As the ester type, there is sorbitan ester and the like, and one or a combination of two or more of them is used.

As the dispersant used in the present invention, partially saponified polyvinyl alcohol having a saponification degree of 60 to 85%,
Examples thereof include ethyl cellulose and methyl cellulose. In the present invention, an emulsifier and a dispersant may be used in combination.

The polymerization initiator used in the present invention is an azo compound such as azobis-α, α'-dimethylvaleronitrile or 2,2'-azobis-2,4-dimethyl-4-methoxyvaleronitrile, or diisopropylperoxy. Dicarbonate, di-2-ethylhexyl peroxydicarbonate, di- (β-ethoxyethyl) peroxydicarbonate, t-butylperoxydicarbonate, acetylcyclohexylsulfonyl peroxide, t-butylperoxypivalate, t- Organized oxides such as butyl peroxyneodecanate and lauroyl peroxide can be mentioned.

The polymerization initiator is used in an amount of 0.0001 to 5 parts by weight based on 100 parts by weight of vinyl chloride.

As other additives, those used in ordinary suspension polymerization of vinyl chloride, such as a polymerization degree adjusting agent, a processability improving agent, an antistatic agent, a pH adjusting agent, an antioxidant, a scale inhibitor, etc. One kind or two or more kinds can be used.

The additive may be added at any time during the polymerization step, but it is usually charged in the same manner as the suspension agent.

The method of the present invention can be carried out within a temperature range in which ordinary suspension polymerization of vinyl chloride is carried out.

Therefore, the temperature of the warmed deionized water used is from polymerization temperature to 100 ° C., preferably 60 to 9
Although it is 0 ° C., this can be appropriately determined according to the polymerization temperature, the amount of hot water charged, the heating capacity from the jacket, the polymerization formulation, and the like.

[0026]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited thereto. Evaluation The powder characteristics and the like in the examples were evaluated as follows. 1. Particle size distribution Measured using a JIS standard sieve. 2. 100 parts by weight of Fisheye A-containing resin DOP 50 〃 Ca-Zn-based stabilizer 2 〃 Ultramarine 3 〃 B Evaluation The above composition was kneaded with a mixing roll at 150 ° C for 3 minutes to prepare a 0.35 mm sheet. Using this sheet, the number of fish eyes in 50 cm2 was counted. 3. Scale adherence ○ Good × Bad 4. Generation of glassy particles ○ Not generated × Generated.

Example 1 A 1 m ³ autoclave was charged with 100 parts by weight of vinyl chloride at room temperature, 55 parts by weight of deionized water and 0.06 part by weight of partially saponified polyvinyl alcohol, and the inside of the autoclave was degassed. Then, 0.02 part by weight of di-2-ethylhexyl peroxydicarbonate, which was emulsified and dispersed in deionized water to emulsify to 40% by weight, was charged,
After charging 100 parts by weight of vinyl chloride at 30 ° C., stirring was started, 75 parts by weight of deionized water heated to 80 ° C. was charged, and the temperature in the autoclave was set to 57 ° C. to start polymerization. Polymerization was stopped when the pressure inside the autoclave decreased by 2.0 kg / cm ² due to the saturated vapor pressure of vinyl chloride at 57 ° C., unreacted vinyl chloride was recovered, and stirring was stopped. The obtained slurry was dehydrated and dried to obtain a chlorinated polymer. Table 1 shows the particle size distribution of the obtained polymer and the result of fisheye test.

Example 2 In Example 1, the reaction temperature (the temperature in the autoclave) was set to 64 ° C., the amount of deionized water added was 35 parts by weight of deionized water at room temperature, and deionized water heated to 80 ° C. was added. The same operation was performed except that the amount was changed to 95 parts by weight. Table 1 shows the test results of the obtained polymer.

Comparative Example 1 130 parts by weight of deionized water at 30 ° C. containing 0.06 part by weight of partially saponified polyvinyl alcohol in a 1 m ³ autoclave was charged into the autoclave and deaerated. Di-emulsified to 40% by weight by emulsifying and dispersing in deionized water
0.02 parts by weight of 2-ethylhexyl peroxydicarbonate and 100 parts by weight of vinyl chloride at 30 ° C. were charged, stirring was started, and the jacket was heated with hot water at 80 ° C. to bring the temperature in the autoclave to 57 ° C. Polymerization was initiated. Then, it was treated under the same conditions as in Example 1 to obtain a vinyl chloride polymer. Table 1 shows the test results of the obtained polymer.
Shown in.

Comparative Example 2 The same procedure as in Example 1 was carried out except that 0.02 part by weight of di-2-ethylhexyl peroxydicarbonate was added without emulsification. Table 1 shows the test results of the obtained polymer.

Comparative Example 3 The same procedure as in Comparative Example 1 was carried out except that the temperature inside the autoclave was set to 64 ° C. Table 1 shows the test results of the obtained polymer.

Comparative Example 4 According to the method described in JP-A-57-5704, 1 m ³ o-
130 parts by weight of deionized water heated to 80 ° C. in a Toclave, 0.006 parts by weight of partially saponified polyvinyl alcohol, 0.002 parts by weight of di-2-ethylhexyl peroxydicarbonate. 100 parts by weight of vinyl chloride at 30 ° C. was charged at the same time with stirring to bring the temperature in the autoclave to 57 ° C. to start polymerization. Then, it was treated under the same conditions as in Example 1 to obtain a vinyl chloride polymer. The test results of the obtained polymer are shown in Table 1.

Comparative Example 5 According to the method described in JP-A-60-47007, 30 parts by weight of deionized water, 10 parts by weight of vinyl chloride at 30 ° C. and partially saponified polyvinyl alcohol in 1 m ³ autoclave were used. ．
06 parts by weight, di-2-ethylhexylperoxydicar
0.002 parts by weight of carbon dioxide was uniformly mixed at a temperature of 30 ° C. or lower, and then deionized water heated to 80 ° C. was added with stirring to 100 parts by weight, and the temperature in the autoclave was adjusted. To 57 ° C. to initiate polymerization. After this, Example 1
A vinyl chloride polymer was obtained by treating under the same conditions as described above. The test results of the obtained polymer are shown in Table 1.

Comparative Example 6 According to the method described in JP-A-54-47785, 30 parts by weight of water at 30 ° C. or less, 0.06 parts by weight of partially saponified polyvinyl alcohol and 1 part of ³ m ³ autoclave were used. 2-Ethylhexylperoxydicarbonate (0.02 parts by weight) was charged, mixed with stirring, and then 100 parts by weight of deionized water heated to 80 ° C. was added to adjust the temperature in the autoclave to 57.
The polymerization was started at ℃. Then, it was treated under the same conditions as in Example 1 to obtain a vinyl chloride polymer. The test results of the obtained polymer are shown in Table 1.

[0035]

[Table 1]

[0036]

As is apparent from the above description, according to the method of the present invention, it is possible to remarkably shorten the temperature rising time in the polymerization of vinyl chloride, and at the same time, to produce fisheye and other physical properties without deteriorating. It is possible to improve the quality.

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[Procedure amendment]

[Submission date] February 6, 1991

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0035

[Correction method] Change

[Correction content]

[0035]

[Table 1]

Claims (1)

[Claims] 1. In a suspension polymerization method of vinyl chloride, 25 to 50% by weight of the total amount of water in the polymerization system in an autoclave.
Deionized water at room temperature and a suspending agent are charged, then a vinyl chloride and a polymerization initiator emulsified and dispersed in an aqueous medium are charged, and after stirring is started, the polymerization temperature is 50 to 80% by weight of the total amount of water in the polymerization system. A suspension polymerization method of vinyl chloride, characterized in that the polymerization system is heated to a predetermined reaction temperature to carry out the polymerization by charging the deionized water heated above.