JP3316891B2 - Method for producing vinyl chloride polymer - Google Patents

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 polymer by a suspension polymerization method, and more particularly to a method for producing a vinyl chloride polymer having excellent fluidity.

[0002]

2. Description of the Related Art A vinyl chloride polymer is usually produced by a suspension polymerization method, separated from a slurry, purified by drying and the like, and then conveyed by pneumatic transportation and then stored or packed in a bag.

[0003] However, the vinyl chloride polymer thus obtained is charged with static electricity due to friction with itself and other objects in the process of transportation and bagging, and its fluidity is reduced.
Since the bulk specific gravity is lower than that of the vinyl chloride polymer immediately after the production, there is a problem that the handling becomes extremely difficult and the operation is seriously hindered. Conventionally, as a method of reducing the adverse effect of such a polymer charge, a method of adding a nonionic surfactant or a cationic surfactant which is an antistatic agent to a vinyl chloride polymer, or a method of adding steam to vinyl chloride. A method of adjusting humidity by blowing into a polymer has been used.

[0004]

However, the above method of adding a surfactant cannot sufficiently prevent a decrease in bulk specific gravity of the polymer, and furthermore, has an adverse effect on the thermal stability and initial coloring property of the product. It has the disadvantage of adverse effects. Further, the method of injecting steam has a drawback that the required labor increases and the equipment becomes complicated. Therefore,
SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a vinyl chloride polymer having a good quality, in which a decrease in bulk specific gravity due to charging hardly occurs.

[0005]

Means for Solving the Problems The present inventors have made intensive studies to achieve the above object, and as a result, completed the present invention. That is, in the present invention, a vinyl chloride monomer or a mixture of vinyl monomers containing vinyl chloride as a main component is subjected to suspension polymerization in an aqueous medium to produce a vinyl chloride polymer. After dehydrating the slurry, ethylene glycol, propylene glycol
And pentaerythritol and their multimers and
Polyhydric alcohol selected from Lyserine at a concentration of 5-90%
Of the vinyl chloride polymer as an aqueous solution of
This is a method for producing a vinyl chloride-based polymer comprising adding 0.01 to 0.5 parts by weight.

In the method of the present invention, first, a vinyl chloride polymer is synthesized by a suspension polymerization method. Examples of the vinyl chloride polymer include a homopolymer of vinyl chloride and a copolymer with another polymerizable vinyl monomer copolymerizable with vinyl chloride. Examples of vinyl monomers copolymerizable with vinyl chloride include alkyl vinyl esters such as vinyl acetate, alkyl vinyl ethers such as cetyl vinyl ether, α-
Monoolefinic monomers, alkyl acrylates such as methyl acrylate, and alkyl methacrylates such as methyl methacrylate are exemplified.

[0007] Suspension polymerization of vinyl chloride polymers is well known and involves the use of a vinyl chloride monomer or a vinyl chloride monomer and another polymerizable vinyl monomer in the presence of a suspending agent and a polymerization initiator. Below, it is polymerized in an aqueous medium. Thus, a slurry containing the vinyl chloride polymer can be obtained by the suspension polymerization method.

Next, according to the method of the present invention, after the slurry containing the vinyl chloride polymer is dehydrated, ethylene polymer is added to the obtained polymer cake or the dried vinyl chloride polymer powder. Glycol, propylene glycol
Cole, pentaerythritol and their multimers
And a polyhydric alcohol selected from glycerin in a concentration of 5 to 9
Add as 0% aqueous solution. Such polyhydric alcohols may be water-soluble polyhydric alcohols containing these as main components. The amount of the polyhydric alcohol added is 0.001 to 100 parts by weight of the vinyl chloride polymer.
It is desirable to add 0.5 parts by weight. If the amount is less than 0.001 part by weight, it is not possible to prevent an extreme decrease in bulk specific gravity due to charging. If the amount exceeds 0.5 parts by weight, the effect of the addition does not increase any more, so it is not economical.

[0009]

EXAMPLES Hereinafter, the present invention will be described specifically with reference to Examples, but the present invention is not limited thereto.

Example 1 In a stainless steel polymerization vessel, 100 parts by weight of vinyl chloride monomer, 150 parts by weight of deionized water, 0.1 part by weight of partially saponified polyvinyl alcohol, and 0.04 part by weight of 2-ethylhexyl peroxydicarbonate Parts, temperature 57
C. and the pressure in the polymerization vessel was 6.0 kg / cm ² G
Was reached, unreacted vinyl chloride monomer was recovered and dehydrated to obtain a vinyl chloride polymer cake containing 20% by weight of water. To the polymer cake thus obtained, ethylene glycol was added as a 50% aqueous solution in an amount of 0.1 part by weight based on the polymer, and then flow-dried at 70 ° C. for 2 hours to obtain a vinyl chloride polymer.

Example 2 In a stainless steel polymerization vessel, 100 parts by weight of vinyl chloride monomer, 150 parts by weight of deionized water, 0.1 part by weight of partially saponified polyvinyl alcohol, and 0.04 part by weight of 2-ethylhexyl peroxydicarbonate Parts, temperature 57
C. and the pressure in the polymerization vessel was 6.0 kg / cm ² G
Unreacted vinyl chloride monomer was recovered when the temperature reached, and after dehydration, it was fluid-dried at 70 ° C for 2 hours to obtain a vinyl chloride polymer. Under a fluidized state, 0.1 parts by weight of ethylene glycol was added to the obtained vinyl chloride polymer as a 50% aqueous solution with respect to the polymer.

Examples 3 to 4 A vinyl chloride polymer was obtained in the same manner as in Example 2 except that the kind, amount of addition and concentration of the aqueous solution of the polyhydric alcohol were changed to the conditions shown in Table 1.

Comparative Example 1 A vinyl chloride polymer was obtained in the same manner as in Example 2 except that ethylene glycol was not added.

Comparative Example 2 A vinyl chloride polymer was obtained in the same manner as in Example 1, except that a 5% aqueous solution of polyoxyethylene sorbitan monolaurate was used instead of ethylene glycol.

The vinyl chloride polymers obtained in Examples 1 to 3 and Comparative Examples 1 and 2 were subjected to a bulk specific gravity measurement test and a thermal stability test. Table 1 shows the results.

1. Bulk specific gravity measurement test After the vinyl chloride polymer was left in a constant temperature and humidity room at a temperature of 23 ° C and a relative humidity of 50% for 48 hours, the bulk specific gravity was measured according to JIS K.
It measured by the method of -6721. Further, the vinyl chloride polymer left for 48 hours under the same conditions as above was stirred at 60 rpm for 2 minutes with a Brabender planetary mixer, and the bulk specific gravity was compared by the same method as above.

2. Thermal stability 100 parts by weight of vinyl chloride polymer, 1.0 part by weight of tribasic lead sulfate 1.5 parts by weight of lead stearate 0.5% by weight of calcium stearate were mixed and kneaded with a roll at 190 ° C. for 5 minutes. Thereafter, a sheet having a heat of 1 mm was prepared, and the sheet was placed in an oven at 190 ° C., and the time until blackening was measured.

[0018]

[Table 1]

[0019]

As described above, according to the present invention, it is possible to obtain a vinyl chloride polymer which is less likely to decrease in bulk specific gravity and has excellent properties such as thermal stability.

Claims (1)

(57) [Claims] 1. A vinyl chloride polymer or a mixture of vinyl monomers containing vinyl chloride as a main component is subjected to suspension polymerization in an aqueous medium to produce a vinyl chloride polymer. after dewatering the slurry containing, ethylene
Glycol, propylene glycol, pentaerythri
Selected from tolls and their multimers and glycerin
Polyhydric method for producing a vinyl chloride polymer, characterized in that alcohol is added 0.001 to 0.5 parts by weight based on the vinyl chloride polymer as an aqueous solution of concentration 5% to 90% that.