JPS60163906A - Suspension polymerization of vinyl chloride - Google Patents

Abstract

PURPOSE:To shorten a feeding time and a heating time necessary for the start of polymerization and to form a vinyl chloride resin of high quality, by feeding water in two divided portions under specified conditions in performing the titled suspension polymerization. CONSTITUTION:An autoclave is charged with 30-90%, based on the total water used, water (30-80 deg.C), a vinyl chloride monomer, a polymerization initiator and a suspending agent, and the mixture is agitated, wherein the temperature of the feed is controlled so that the temperature of the polymerization system after starting agitation may be about 50 deg.C or below and further below the cloud point (or gelation temperature) of the suspending agent. The balance of the water is added at a temperature >= the polymerization temperature, and the reaction mixture is suspension-polymerized at a predetermined temperature to produce a polyvinyl chloride polymer. The obtained vinyl chloride resin has a low fish eye content and a good particle diameter distribution.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a suspension polymerization method for vinyl chloride monomers, which aims to improve the stability and particle size distribution.

Normally, the suspension polymerization method for vinyl chloride is carried out in a batch process, in which water (deionized water), a suspending agent, a polymerization initiator, and other additives are charged into an autoclave, and then the system is degassed to produce vinyl chloride. The system monomers are charged and heated to the polymerization temperature by circulating hot water or passing steam through the jacket of the autoclave while stirring, and then the polymerization reaction is started. When the heat of the polymerization reaction is released, cooling water is passed through the jacket of the autoclave to polymerize. The temperature is maintained and the reaction is continued until a predetermined polymerization rate is reached. Next, the monomer gas of the vinyl chloride monomer is recovered, the polymer is discharged from the autoclave, and a series of polymerization operations are performed. However, in the conventional methods described above, the time required to start polymerization is 5 to 30% of one cycle of polymerization operation.
This is a cause of decreased productivity. Various methods can be considered to solve this problem.

For example, in the method described in JP-A-54-47785, in which cold water at 30°C or lower and a suspending agent are charged into an autoclave, vinyl chloride is then charged, and then heated water is charged to initiate polymerization. Since the following cold water is added, the last water must be heated to a fairly high temperature in order to raise the temperature to near the reaction temperature.As a result, the suspending agent 9 polymerization initiator, vinyl chloride monomer and high temperature water Since particles come into contact with each other non-uniformly, the particle size becomes unstable, and if this is avoided, the preparation time becomes longer and the temperature rise time becomes longer, which poses practical problems.

The present inventors have carried out intensive studies to solve these drawbacks and shorten the cycle time of the polymerization process. As a result, the temperature and It was discovered that the ratio of vinyl chloride monomer to water is an important factor, leading to the present invention.

That is, when the vinyl chloride monomer, water, suspending agent, and polymerization initiator are stirred and mixed in an autoclave, a stable suspension state is obtained if the temperature is 50 ° C. or lower and 30% or more of the total amount of water is present. This is a suspension polymerization method for vinyl chloride that is characterized by charging the remaining water at a temperature higher than the reaction temperature in order to shorten the heating time.

According to the method of the present invention, it is possible to significantly shorten the charging time to an autoclave and the temperature raising time, and it is also possible to improve productivity without impairing fish eyes or other physical properties.

The present invention will be explained in more detail.

In an autoclave at a temperature of 30-80℃, 3 out of the total amount of water
After charging 0 to 90% water, a vinyl chloride monomer 9 polymerization initiator, and a suspending agent sequentially or simultaneously, start stirring the autoclave, and keep the internal temperature below 50°C after the start of stirring and the suspending agent. 1 so that the temperature is below the cloud point or below the gelling temperature.
It is necessary to adjust the temperature of the water or vinyl chloride monomer.

Above the clouding point or gelling temperature of the suspending agent, coarse particles are often produced, and when the autoclave internal temperature is above 509C, the decomposition of the polymerization initiator becomes large, resulting in a rapid increase in scale production and fish eyes.

Finally, the remaining water is charged at a temperature higher than the reaction temperature in order to shorten or omit the heating time.

Depending on the type of suspending agent, it may be necessary to adjust the temperature and charging speed of the remaining hot water, or to charge while spraying.The last water to be charged so that the temperature is close to the polymerization temperature when the entire amount of water has been charged. It is preferable to adjust the temperature in order to save time.

As the vinyl chloride monomer used in the present invention, vinyl chloride or a mixture of vinyl chloride and a monomer copolymerizable with vinyl chloride as a main component can be used.

Monomers copolymerizable with vinyl chloride include, for example, olefins such as ethylene and propylene, vinyl esters such as vinyl acetate and vinyl propionate, acrylic esters such as methyl acrylate, other maleic anhydride, and acrylonitrile. , vinylidene chloride, etc.

Examples of the polymerization initiator used in the present invention include perester compounds such as t-butylperoxyneodecanate, α-cumylperoxyneodecanate, 1-butylperoxybivalate, and diisopropylperoxydicarbonate. , percarbonate compounds such as jetoxyethyl peroxydicarbonate, azo compounds such as αα′αchibis-2,4 dimethylvaleronitrile, αα′-azobisisobutyronitrile, and the like.

Suspending agents include cellulose derivatives such as methylcellulose, hydroxyethylcellulose, hydroxybrobylcellulose, and hydroxypropylmethylcellulose, partially saponified polyvinyl alcohol, acrylic acid polymers, gelatin, and sorbitan ester polyester polymers. They can be used alone or in combination of two or more.

Substances added to the polymerization system 2 Polymerization temperature (usually 40-80°
C) There are no particular restrictions on other operating conditions or equipment.

Hereinafter, it will be explained in more detail with reference to Examples.

Example 1 First, 60°C water (deionized water) was added to a 7-autoclave.
After charging 60 parts (9 to 1200) and then degassing the system, 100 parts (2000 kg) of vinyl chloride at 30°C,
0.067 parts of a 30% isoparaffin solution of t-butyl peroxyneodecanate (containing 0.02 parts (0.4 kg) of 1-butyl peroxyneodecane), and partially saponified polyvinyl alcohol (0.1 A 2% aqueous solution containing 0.06 (1.2 ky) (aqueous solution point: 48°C) was sequentially charged.

Next, stirring was started, and the internal temperature thereafter became 45°C. After 5 minutes of stirring, add 70 parts of 73°C water (9 to 1400) to 10
The preparation was completed within minutes.

At this time, the autoclave internal temperature became 57°C. Cooling water was passed through the jacket of the autoclave to carry out a polymerization reaction at a temperature of 57°C, and when the internal pressure of the autoclave decreased by 2.0jC9/d, the polymerization was stopped and unreacted monomers were collected and dehydrated and dried to obtain a vinyl chloride polymer. Table 1 shows the particle size distribution of the obtained polymer and the fish eye test results.

Example 2 In the method of Example 1, the temperature of the first water was changed from 60°C to 50°C, the temperature of vinyl chloride was changed from 30°C to 40°C,
A vinyl chloride polymer was obtained by processing under the same conditions as in Example 1, except that the temperature of the water charged last was changed from 75 to 80. The test results are shown in Table-1.

Example 3 In the method of Example 1, the first amount of water was changed from 60 parts to 40 parts, the temperature was changed from 60°C to 75°C, the last water was changed from 70 parts to 90 parts, and the temperature was changed from 73°C to 70°C. A vinyl chloride polymer was obtained by processing under the same conditions as in Example 1 except that the temperature was changed to .degree.

The test results are shown in Table-1.

Comparative Example 1 In Example 1, the temperature of the first water was changed from 60°C to 50°C.
A vinyl chloride polymer was obtained by carrying out the treatment under the same conditions as in Example 1 except that the amount was changed from 60 parts to 150 parts and the water added at the end was omitted.

The test results are shown in Table-1.

Comparative Example 2 In Example 1, the temperature of the first water was changed from 60°C to 30°C.
℃, change the amount from 60 parts to 20 parts, and finally change the temperature of the water to 73°C to 74°C, and change the amount from 70 parts to 1.
A vinyl chloride polymer was obtained by processing under the same conditions as in Example 1 except that the amount was changed to 10 parts.

The test results are shown in Table-1.

Engraving of the statement (no changes to the contents) Engraving of the statement (no changes to the contents) 1) The fish eye test was conducted as follows.

Vinyl chloride polymer 100 parts Dioctyl 7-talate 50 parts Calcium stearate 1.5 parts Barium stearate 1.5 parts Ultramarine 3 parts were mixed and kneaded for 5 minutes at a pul temperature of 150°C, and then a sheet of thickness α3511I11 was prepared. Created and has an area of 25crI!
Perform fisheye measurements of the sheet.

Patent Applicant Toyo Soda Kogyo Co., Ltd. Procedural Amendment [Method] May 16, 1980 Commissioner of the Japan Patent Office Kazuo Wakasugi 1 Display of Case 1989 Patent Application No. 19347 2 Name of Invention Suspension of vinyl chloride Polymerization law telephone number (585) 311 4. Date of amendment order April 4, 1980 5. Detailed explanation of the invention in the specification to be amended 6. Contents of the amendment Full text including Table 1 on page 11 amended as shown in the attached sheet.

7 List of Attached Documents (1) A document with the entire text of page 11 of the specification printed in No. 4 brackets.

Claims (4)

[Claims] (1) In the suspension polymerization method of vinyl chloride, 30 to 90% of the total amount of water present in the polymerization system at a temperature of 30 to 100 ° C. is charged to the autoclave as the first water,
A method for suspension polymerization of vinyl chloride, which is characterized in that a vinyl chloride monomer dipolymerization initiator and a suspending agent are then charged, and finally, the remaining water is charged in a state of water hotter than the polymerization temperature. (2) First water, vinyl chloride monomer 1 polymerization initiator,
The vinyl chloride suspension polymerization method according to claim 1, wherein stirring of the autoclave is started after the suspension agent is completely charged. (3) First water, vinyl chloride monomer 1 polymerization initiator,
The temperature of the water for the first time is adjusted so that the temperature inside the autoclave after the suspension agent has been charged is 50°C or lower and is lower than the clouding point or thermal gelation temperature of the suspension agent. A suspension polymerization method for vinyl chloride according to claim 1. (4) A method for suspension polymerization of vinyl chloride according to claim 1, characterized in that the temperature of the last charged hot water is adjusted so that the temperature inside the autoclave after the completion of charging the entire amount of water is around the reaction temperature. .