JP2912955B2 - Suspension polymerization of vinyl chloride - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a suspension polymerization method for vinyl chloride or a monomer mixture containing vinyl chloride as a main component and copolymerizable therewith (hereinafter referred to as vinyl chloride). Also, the present invention relates to a suspension polymerization method for improving productivity in a polymerization step by shortening a heating time, and also for improving fisheye, particle size distribution and preventing scale adhesion.

[0002]

2. Description of the Related Art Generally, suspension polymerization of vinyl chloride is carried out in a batch system. After deionized water, a suspending agent, a polymerization initiator and additives are charged into an autoclave, the inside of the system is degassed, and vinyl chloride or the like is degassed. , And warm water circulation or steam is passed through the autoclave jacket with stirring, and the temperature is raised to the polymerization temperature to start the polymerization reaction. Thereafter, from the point when the polymerization reaction heat comes out, cooling is performed to keep the polymerization temperature constant by passing cooling water through the autoclave jacket, the reaction is continued until a predetermined polymerization rate is reached, and then a monomer gas such as vinyl chloride is discharged. A series of polymerization operations for recovering and discharging the polymer from the autoclave are performed.

[0003]

However, in the above-mentioned conventional method, the time required for the temperature rise time is one of the causes of a decrease in productivity. In order to solve such a problem, various methods have been considered.

[0004] Water, a suspension, an agent, vinyl chloride and the like and a polymerization initiator heated to a polymerization temperature or higher as disclosed in JP-A-57-5704 are charged together in an autoclave, and the polymerization reaction is started immediately. There is a method, but in this method, vinyl chloride, water, and a suspending agent come into contact with each other at a temperature around the polymerization temperature, so that the particle size becomes unstable, and the number of products particularly coarse is increased. In addition, there is a disadvantage in quality that the number of fish eyes is remarkably increased, which is not a good idea. Or, JP-A-60-470
There is a method in which a suspension agent, a polymerization initiator, other additives and vinyl chloride are charged into an autoclave as described in No. 07, and then water heated at or above the polymerization temperature is added. Scale is formed, and it is difficult to homogenize the polymerization at the initial stage of charging hot water, and coarse particles are formed, resulting in a poor fisheye product.

[0005] Japanese Patent Application Laid-Open No.
In a method in which water at 0 ° C or lower, a suspending agent and a polymerization initiator are charged into an autoclave, then vinyl chloride is charged, and the mixture is stirred and mixed, then heated water is charged to start polymerization, and considerable scale is generated on the inner wall of the polymerization can. And has practical problems.

[0006]

Means for Solving the Problems The present inventors have made intensive studies to solve this drawback and to shorten the cycle time of the polymerization step. As a result, the timing of starting stirring, the method of using the polymerization inhibitor, and the polymerization method are described. By devising a method for charging the initiator, the above-mentioned disadvantages were solved, and the present invention was achieved.

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, a suspending agent, and a polymerization inhibitor are charged into an autoclave and stirred with stirring. After the start of the polymerization, the inside of the polymerization system is heated up to the reaction temperature by charging vinyl chloride and 50 to 80% by weight of the total amount of water in the polymerization system with deionized water heated above the polymerization temperature. An object of the present invention is to provide a suspension polymerization method of vinyl chloride, which comprises charging an initiator and polymerizing.

The present invention will be described in more detail.

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

The suspending agent used in the present invention may be any of those conventionally known, including styrene / maleic acid copolymer, partially saponified polyvinyl alcohol, methylcellulose, hydroxypropylmethylcellulose, ethylcellulose, gelatin, calcium carbonate , Calcium phosphate and the like are used alone or in combination of two or more.

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. The polymerization inhibitor used in the present invention may be a polymerization inhibitor having an effect of generally inhibiting the polymerization reaction of vinyl chloride, and phenol-based, phosphite-based, thioether-based, and thiazole-based polymerization inhibitors are used.

Examples of the phenolic polymerization inhibitor include hydroquinone, butylated hydroxytoluene, hydroquinone monomethyl ether, 3,9-bis [1,1-dimethyl-2- @ β- (3-t-butyl-4-hydroxy-hydroxy).
5-methylphenyl) propionyloxydiethyl]-
2,4,8,10-tetraoxaspiro [5.5] undecane, 4,4'-butylidenebis- (6-t-butyl-3-methylphenol, dibutylhydroxytoluene, octadecyl-3- (3,5- Ditertiarybutyl-4-hydroxyphenol) -propionate, pentaerythrityl-tetrakis [3- (3,5-di-t-
Butyl-4-hydroxyphenol) propionate]
n-octadecyl-β- (4′-hydroxy-3 ′,
5'-di-t-butylfeil) propionate, n-
Octadecyl-β- (4′-hydroxy-35′-di-
(t-butylphenyl) propionate, dilaurylthiodipropionate and the like.

Examples of the phosphite-based polymerization inhibitor include triphenyl phosphite, diphenyldecyl phosphite, trioctyl phosphite, and 4,4'-butylidene-bis (3-methyl-6-t-butylphenyl-di-). Tridecyl) phosphite and the like.

As a thioether-based polymerization inhibitor, 2,4
-Bis [(octylthio) methyl] -o-cresol and the like.

Examples of the thiazole polymerization inhibitor include 2-mercaptobenzothiazole, dibenzothiazulsulfide and the like.

One or two or more of these polymerization inhibitors can be used. The total amount of the polymerization inhibitors is 0.005-0.
05 parts by weight are preferred. If the amount is less than 0.005 parts by weight, the effect is not so large. If the amount exceeds 0.05 parts by weight, the polymerization reaction is undesirably delayed.

Other additives used in ordinary suspension polymerization of vinyl chloride, such as a polymerization degree regulator, a processability improver, an antistatic agent, a pH regulator, an antioxidant, a scale inhibitor, etc. One type or two or more types can be used.

The timing of adding the additives may be in any of the polymerization steps, but is usually charged in the same manner as the charging of the suspending agent.

A stable dispersion state can be obtained by sufficiently mixing the suspending agent, polymerization inhibitor and water at room temperature.

More specifically, it is preferable to carry out the above-mentioned mixing at a temperature not higher than the cloud point or thermal gelation temperature of the suspending agent used,
Above this temperature, the formation of coarse particles increases.

As described above, 20 to 50 deionized water at room temperature is used.
After charging the suspending agent and the polymerization inhibitor to the weight%, the inside of the autoclave is usually subjected to a deaeration treatment to remove the air present in the autoclave. After starting the stirring, preferably,
After the stirring is in a steady state, vinyl chloride and deionized water heated to a polymerization temperature of 50 to 80% by weight or more of the total amount of water to be present in the polymerization system are charged to a predetermined reaction temperature in the polymerization system. The temperature is then raised, and then a polymerization initiator is charged to immediately polymerize.

The vinyl chloride used in the present invention includes:
Mixtures of vinyl chloride or monomers based on vinyl chloride and copolymerizable therewith can be used. Examples of components copolymerizable with vinyl chloride include ethylene, vinyl acetate, methyl acrylate, acrylonitrile, and vinylidene chloride.

The polymerization initiator used in the present invention includes azo compounds such as azobis-α, α'-dimethylvaleronitrile and 2,2'-azobis-2,4-dimethyl-4-methoxyvaleronitrile, and diisopropylperoxy. Dicarbonate, di-2-ethylhexylperoxydicarbonate, di- (β-ethoxyethyl) peroxydicarbonate, t-butylperoxydicarbonate, acetylcyclohexylsulfonyl peroxide, t-butylperoxypivalate, t-butylperoxydicarbonate Organic peroxides such as butylperoxyneodecanate and lauroyl peroxide are exemplified.

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.

These polymerization initiators can be used together with a diluent. Examples of the diluent include lower alcohols such as methanol and ethanol, aromatic hydrocarbons such as toluene and xylene, aliphatic hydrocarbons having 12 or more carbon atoms and liquid at ordinary temperature, and acetone.

The dilution ratio is preferably from 5 to 50% by weight. Because the polymerization initiator is dispersed uniformly,
This is because stability of particle size and reduction of fish eyes can be achieved. If the amount is less than 5% by weight, the amount of diluent increases, which is not economical. If the amount exceeds 50% by weight, the effect of using the diluent may not be sufficiently exhibited.

The process of the present invention can be carried out in a temperature range in which ordinary suspension polymerization of vinyl chloride is carried out. Therefore, the temperature of the heated deionized water to be used is water having a polymerization temperature of 100 ° C., preferably 60 to 90 ° C., which includes a polymerization temperature, a charged amount of hot water, a heating capacity from a jacket, and a polymerization temperature. It can be determined appropriately according to the prescription and the like.

[0028]

EXAMPLES The present invention will be described below with reference to examples, but the present invention is not limited by these examples. Evaluation The evaluation of powder characteristics and the like in the examples was performed as follows. Particle size distribution Measured using a JIS standard sieve. 2. Fisheye A blended resin 100 parts by weight DOP50 {Ca-Zn-based stabilizer 2} ultramarine blue 3} B evaluation The above blend 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 cm ² was counted. 3. Scale adhesion status ○ good × bad 4. Generation of glassy particles ○ Not generated × Generated.

Example 1 A 1 m ³ autoclave was charged with 55 parts by weight of deionized water, 0.06 parts by weight of partially saponified polyvinyl alcohol, and 0.02 parts by weight of dibutylhydroxytoluene per 100 parts by weight of vinyl chloride at room temperature. The inside of the autoclave was evacuated.

After the stirring is started, 100 ° C. of vinyl chloride at 30 ° C.
Parts by weight and then heated to 80 ° C. with deionized water 7
5 parts by weight were charged, the temperature in the autoclave was adjusted to 57 ° C., and then 0.02 parts by weight of di-2-ethylhexylperoxydicarbonate was charged to initiate polymerization. When the pressure in the autoclave dropped 2.0 kg / cm ² due to the saturated vapor pressure of vinyl chloride at 57 ° C., polymerization was stopped, unreacted vinyl chloride was recovered, and stirring was stopped. The obtained slurry was dehydrated and dried to obtain a vinyl chloride polymer. Table 1 shows the particle size distribution of the obtained polymer and the results of the fisheye test.

Example 2 The procedure of Example 1 was repeated except that 0.02 parts by weight of di-2-ethylhexyl peroxydicarbonate was changed to a 30% by weight solution with methanol. Table 1 shows the test results of the obtained polymer.

Example 3 In Example 1, 100 parts by weight of vinyl chloride at 30.degree. C. and 75 parts by weight of deionized water heated to 80.degree. C. were simultaneously charged, and the temperature in the autoclave was reduced to 57.degree.
2-ethylhexyl peroxydicarbonate 0.02
The same procedure was carried out except that the polymerization was started by charging parts by weight. Table 1 shows the test results of the obtained polymer.

Example 4 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 procedure was exactly the same except that the weight was changed to 95 parts by weight. Table 1 shows the test results of the obtained polymer.

COMPARATIVE EXAMPLE 1 In a 1 m ³ autoclave, partially saponified polyvinyl alcohol (0.06 wt.), Dibutylhydroxytoluene (0.06 wt.
130 parts by weight of 30 ° C. deionized water containing 2 parts by weight was charged and degassed. Stirring was started and vinyl chloride 10 ° C at 30 ° C.
After charging 0 parts by weight, the jacket was heated with warm water of 80 ° C. to adjust the temperature in the autoclave to 57 ° C., and then di-2-ethylhexyl peroxydicarbonate 0.06% was added.
The polymerization was started by charging 2 parts by weight. Thereafter, the first embodiment
Treatment under the same conditions as described above yielded a vinyl chloride polymer. Table 1 shows the test results of the obtained polymer.

Comparative Example 2 55 parts by weight of deionized water and 0.06 parts by weight of partially saponified polyvinyl alcohol were charged into a 1 m ³ autoclave.
The inside of the autoclave was evacuated. Vinyl chloride 10 at 30 ° C
After charging 0 parts by weight and 0.02 parts by weight of di-2-ethylhexyl peroxydicarbonate, stirring was started,
Subsequently, 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 initiate polymerization. Thereafter, the mixture 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 polymers.
Shown in

Comparative Example 3 The same operation as in Comparative Example 1 was carried out except that the temperature in the autoclave was changed 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
130 parts by weight of deionized water heated to 80 ° C. in a reactor, 0.006 parts by weight of partially saponified polyvinyl alcohol, and 0.002 parts by weight of di-2-ethylhexylperoxydica-ponate. 100 parts by weight of vinyl chloride at 30 ° C. were charged simultaneously with stirring, and the temperature in the autoclave was set to 57 ° C. to initiate polymerization. Thereafter, the mixture 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.

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 0 parts of partially saponified polyvinyl alcohol were placed in a 1 m ³ autoclave. .
06 parts by weight, di-2-ethylhexyl par-oxydica
0.002 parts by weight of carbonate is uniformly mixed at a temperature of 30 ° C. or less, and then, while stirring, deionized water heated to 80 ° C. is charged to 100 parts by weight, and the temperature in the autoclave is increased. At 57 ° C. to initiate polymerization. Thereafter, the first embodiment
The mixture 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.

[0039] according to the method described in Comparative Example 6 Sho 54-47785, 1m ³ O - Tokure - 30 parts by weight of water of 30 ° C. or less during blanking, partially saponified polyvinyl alcohol - Le 0.06 parts by weight, di After charging 0.02 parts by weight of 2-ethylhexylperoxydica-bonate and stirring and mixing, 100 parts by weight of deionized water heated to 80 ° C. was charged to reduce the temperature in the autoclave to 57%.
C. to initiate polymerization. Thereafter, the mixture 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.

[0040]

[Table 1]

[0041]

As is apparent from the above description, according to the method of the present invention, it is possible to remarkably reduce the temperature rise time in the polymerization of vinyl chloride, and also to produce fisheye without impairing the physical properties. It is possible to improve the performance.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) C08F 2/00 C08F 2/18-2/20 C08F 2/38-2/42

Claims (1)

(57) [Claims] In a suspension polymerization method of vinyl chloride, 20 to 50% by weight of the total amount of water in a polymerization system is contained in an autoclave.
After charging normal temperature deionized water, a suspending agent, and a polymerization inhibitor, and starting stirring, the total water amount of vinyl chloride and the polymerization system is 50 to 50%.
By charging deionized water heated to a polymerization temperature of 80% by weight or more, the temperature inside the polymerization system was raised to the reaction temperature,
Subsequently, a suspension polymerization method of vinyl chloride, wherein a polymerization initiator is charged and polymerization is performed.