JPH09194509A - Production method of vinyl chloride polymer with good powder flowability - Google Patents

Abstract

(57) [Abstract] [Problem] It is difficult for the bulk specific gravity to decrease due to charging,
Provided is a method for producing a vinyl chloride polymer having good thermal stability. SOLUTION: In producing a vinyl chloride polymer,
A partially saponified polyvinyl acetate having a cloud point lower than the temperature of the polymer slurry when measured in a 1 wt% aqueous solution is added to the vinyl chloride polymer 100.
The present invention relates to a method for producing a vinyl chloride-based polymer, which is characterized by adding 0.005-0.5 parts by weight to parts by weight.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD 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 good powder fluidity. Is.

[0002]

2. Description of the Related Art Vinyl chloride polymers are generally produced by a suspension polymerization method, and after separation from a slurry, drying, etc., they are conveyed by air transportation and then stored or packed.

However, the vinyl chloride polymer is charged with static electricity due to friction with itself or other substances during transport and bagging, and its fluidity is lowered, so that the vinyl chloride polymer is bulkier than the vinyl chloride polymer immediately after production. Since the specific gravity is reduced, it becomes extremely difficult to handle, and there is a problem that work is seriously hindered. As a method for reducing the adverse effect of the electrification of such a vinyl chloride polymer, conventionally, a method of adding a nonionic surfactant or a cationic surfactant, which is a surfactant, to the vinyl chloride polymer or A method of blowing steam into a vinyl chloride polymer has been used.

[0004]

However, in the method of adding the above-mentioned surfactant, not only the decrease in bulk specific gravity of the polymer cannot be sufficiently prevented, but also the thermal stability of the polymer, the initial stage It has the drawback of adversely affecting the colorability. Further, the method of blowing steam has drawbacks such as an increase in required labor force and complication of equipment.

Therefore, an object of the present invention is to provide a method for producing a vinyl chloride polymer having good quality, by which addition of a specific compound hardly causes a decrease in bulk specific gravity due to charging. It is in.

[0006]

Means for Solving the Problems As a result of intensive studies for solving the above-mentioned problems, the present inventors have found that a vinyl chloride polymer is less likely to decrease in bulk specific gravity due to electrification, and has a good quality. The inventors have found a method for producing a vinyl polymer and completed the present invention.

That is, according to the present invention, when a vinyl chloride-based monomer is suspension-polymerized in an aqueous medium to produce a vinyl chloride-based polymer, a vinyl chloride-based polymer slurry is measured with a 1 wt% aqueous solution. A vinyl chloride polymer, characterized in that 0.005-0.5 parts by weight of partially saponified polyvinyl acetate having a cloud point lower than the temperature of the polymer slurry is added to 100 parts by weight of the vinyl chloride polymer. It provides a manufacturing method of.

Hereinafter, the present invention will be described in detail.

In the present invention, the vinyl chloride polymer is produced by a general suspension polymerization method.

Examples of the vinyl chloride polymer in the present invention include vinyl chloride homopolymers and vinyl chloride copolymers.

In the present invention, as the vinyl chloride-based monomer for producing the vinyl chloride-based polymer, vinyl chloride monomer or vinyl copolymerizable vinyl chloride monomer and vinyl chloride monomer is used. A mixture with a system monomer can be mentioned. Examples of vinyl monomers copolymerizable with vinyl chloride monomers include alkyl vinyl esters such as vinyl acetate; alkyl vinyl ethers such as cetyl vinyl ether; olefinic monomers such as ethylene and propylene; acryl. Examples thereof include alkyl acrylates such as methyl acidate, ethyl acrylate and propyl acrylate; alkyl methacrylates such as methyl methacrylate, ethyl methacrylate and propyl methacrylate.

Suspension polymerization of the vinyl chloride polymer in the present invention may be carried out by a generally known method, for example, in the presence of a vinyl chloride monomer as a suspending agent and a polymerization initiator. The method of polymerizing in an aqueous medium can be mentioned,
A slurry containing a vinyl chloride polymer can be obtained.

In the present invention, partially saponified polyvinyl acetate having a cloud point lower than the temperature of the polymer slurry when measured with a 1 wt% aqueous solution is added in an amount of 0.005 to 0.5 based on 100 parts by weight of the vinyl chloride polymer. Add parts by weight.

Here, the cloud point of the partially saponified polyvinyl acetate in the 1 wt% aqueous solution is determined by the temperature at which the aqueous solution is heated at a temperature rising rate of 1 ° C. per minute and the aqueous solution starts to become turbid. . The cloud point of the partially saponified polyvinyl acetate in the 1 wt% aqueous solution is generally determined by the degree of polymerization and the degree of saponification of the partially saponified polyvinyl acetate.

The partially saponified polyvinyl acetate used in the present invention is not particularly limited as long as the cloud point of a 1 wt% aqueous solution is not higher than the temperature of the polymer slurry to which it is added.
Further, partially saponified polyvinyl acetate having the following combination of polymerization degree and saponification degree can be exemplified. For example, average degree of polymerization 2200, degree of saponification 80%, partially saponified polyvinyl acetate having a cloud point of 45 ° C., average degree of polymerization 2600, degree of saponification 8
0%, partially saponified polyvinyl acetate having a cloud point of 46 ° C, average degree of polymerization 850, saponification degree 73%, partially saponified polyvinyl acetate having a cloud point of 33 ° C, average degree of polymerization 850, saponification degree 80
%, Partially saponified polyvinyl acetate having a cloud point of 45 ° C., average degree of polymerization of 400, saponification degree of 70%, partially saponified polyvinyl acetate having a cloud point of 24 ° C., and the like.

The amount of partially saponified polyvinyl acetate used in the present invention is 0.005 to 0.5 part by weight based on 100 parts by weight of the vinyl chloride polymer. The amount added is 0.0
If it is less than 05 parts by weight, it is not possible to prevent an extreme decrease in the bulk specific gravity due to charging. On the other hand, even if the amount added exceeds 0.5 parts by weight, the effect of the addition does not increase any more, which is not economical.

In the present invention, when the partially saponified polyvinyl acetate is added to the vinyl chloride polymer slurry, the temperature of the polymer slurry is higher than the cloud point of the 1 wt% aqueous solution of the partially saponified polyvinyl acetate to be added. There must be.
Even if a predetermined amount of partially saponified polyvinyl acetate is added to the polymer slurry below the cloud point temperature, a vinyl chloride polymer having the desired effect cannot be obtained.

In the present invention, when the partially saponified polyvinyl acetate is added to the vinyl chloride polymer slurry, the partially saponified polyvinyl acetate is added to the polymer slurry having a temperature higher than the cloud point of a 1 wt% aqueous solution of the partially saponified polyvinyl acetate. Any method may be used as long as it is possible to add the saponified polyvinyl acetate. Examples of such a method include a partially saponified polyvinyl acetate simple substance, a partially saponified polyvinyl acetate dispersion or a partially saponified polyvinyl acetate. The method of adding a vinyl acetate solution can be mentioned. It is preferable to add a homogeneous solution of partially saponified polyvinyl acetate because a vinyl chloride polymer having antistatic properties can be obtained easily and efficiently. Then, as a solvent for obtaining such a homogeneous solution, for example, water, methanol, ethanol, acetone or a mixed solvent thereof can be mentioned.

[0019]

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

The polymers obtained in Examples and Comparative Examples were evaluated under the conditions shown below.

-Bulk Specific Gravity Measurement Test- After leaving the obtained polymer 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 was measured by the method of 6721.

Further, the vinyl chloride polymer left under the same conditions as above for 48 hours was stirred at 60 rpm for 2 minutes with a Brabender planetary mixer, the bulk specific gravity was determined by the same method as above, and the results were compared to charge. The preventive property was evaluated.

-Heat Stability- 100 parts by weight of the obtained polymer was blended with 1.0 part of tribasic lead sulfate, 1.5 parts of lead stearate and 0.5 part of calcium stearate, and a roll at 190 ° C. After kneading for 5 minutes with a processing machine, a sheet with a thickness of 1 mm is prepared, and this sheet is subjected to 190
It was placed in an oven at ℃ and the time until blackening was measured.

Example 1 100 parts by weight of vinyl chloride monomer, 150 parts by weight of deionized water, 0.1 part by weight of partially saponified polyvinyl alcohol, 0.04 part by weight of 2-ethylhexyl peroxydicarbonate were placed in a stainless steel polymerization vessel. When the pressure inside the polymerization vessel reached 6.0 kg / cm ² G, unreacted vinyl chloride monomer was recovered to obtain a vinyl chloride polymer slurry. With the polymer slurry thus obtained kept at 57 ° C., 100 parts by weight of partially saponified polyvinyl acetate having an average polymerization degree of 2600, a saponification degree of 80% and a 1 wt% aqueous solution having a cloud point of 46 ° C. are vinyl chloride polymers. Then, a 1 wt% aqueous solution was added so as to be 0.01 part by weight, dehydrated, and then fluidized and dried at 70 ° C. for 2 hours to obtain a vinyl chloride polymer.

Table 1 shows the evaluation results of the obtained vinyl chloride polymer.

Examples 2 to 5 Vinyl chloride polymers were obtained in the same manner as in Example 1 except that partially saponified polyvinyl acetate and the addition conditions were those shown in Table 1.

Table 1 shows the evaluation results of the obtained vinyl chloride polymer.

Comparative Examples 1 to 3 Vinyl chloride polymers were prepared in the same manner as in Example 1 except that the slurry temperature, the partially saponified polyvinyl acetate and the partially saponified polyvinyl acetate were added as shown in Table 1. Obtained.

Table 1 shows the evaluation results of the obtained vinyl chloride polymer.

[0030]

[Table 1]

[0031]

INDUSTRIAL APPLICABILITY The method of the present invention relates to a method for producing a vinyl chloride polymer having a good thermal stability in which a decrease in bulk specific gravity due to electrification does not easily occur, and its industrial value is very high. is there.

Claims (1)

[Claims] 1. A suspension-polymerization of a vinyl chloride monomer or a mixture of vinyl-based monomers having vinyl chloride monomer as a main component (hereinafter referred to as vinyl chloride-based monomer) in an aqueous medium, In producing a vinyl chloride-based polymer, a partially saponified polyvinyl acetate having a cloud point lower than the temperature of the polymer slurry when measured in a 1 wt% aqueous solution is added to the vinyl chloride-based polymer 100. 0.0 to parts by weight
A process for producing a vinyl chloride-based polymer, which comprises adding 05 to 0.5 part by weight.