JP2000309602A - Production of vinyl chloride-based polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a high-bulk density vinyl chloride- based polymer without causing the problem of the cloudiness of waste water. SOLUTION: This method for producing a vinyl chloride-based polymer is to use a polymer suspension dispersion stabilizer comprising (a) a partially saponified polyvinyl acetate having a specific saponification degree, (b) at least one kind or a combination of two or more kinds selected from the group consisting of a partially saponified polyvinyl acetate having a specific saponification degree, methyl cellulose, hydroxypropylmethyl cellulose, carboxymethyl cellulose, polyvinyl pyrrolidone, polyacrylic acid, a vinyl acetate-maleic acid copolymer, gelatin, starch and polyethylene oxide, and (c) a metal salt of alkali metals.

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, and more particularly to a method for producing a vinyl chloride polymer having excellent polymerization stability, transparent polymerization wastewater and high bulk specific gravity. About the law.

[0002]

2. Description of the Related Art Vinyl chloride resins are inexpensive and have excellent quality balance, and are therefore used in various fields such as soft and hard fields. For example, in the soft field, there are wire coatings, wrap films, sheets, etc., and in the hard field, pipes, window frames, films, etc.

[0003] On the other hand, vinyl chloride resin as a material is a general-purpose resin in which inexpensiveness is an essential requirement, but various characteristics are required also in terms of performance, and a particularly high discharge rate is required in terms of productivity during processing. Therefore, a resin having high bulk specific gravity and excellent workability is required.

As means for obtaining a resin having a high bulk specific gravity and excellent processability, JP-A-9-241308 and JP-A-10-251313 disclose partially saponified polyvinyl acetate having a saponification degree of 85% or more. A method of using at least one kind in combination is disclosed. However, in such a method, although the bulk specific gravity becomes high, there is a problem that the polymerization effluent becomes cloudy and the chemical oxygen demand (COD) becomes high.

[0005]

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned prior art, and solves the problems associated with the method of using a partially saponified polyvinyl acetate having a high degree of saponification as a dispersant, that is, a method of discharging waste water. Provided is a method for producing a vinyl chloride-based polymer using a specific polymer suspension / dispersion stabilizer and a metal salt, capable of producing a vinyl chloride-based polymer having a high bulk specific gravity without causing the problem of cloudiness. The purpose is to:

[0006]

Means for Solving the Problems The present inventors have conducted intensive studies so as to make the wastewater transparent while maintaining quality characteristics, and as a result, have adopted a specific polymer suspension / dispersion stabilizer and a metal salt. Thus, the present invention has been found to make it possible to make the waste water transparent without causing a quality problem.

That is, the present invention relates to a vinyl chloride monomer or a mixture of a vinyl chloride monomer and a monomer copolymerizable with the vinyl chloride monomer (hereinafter, referred to as “vinyl chloride monomer”). The water-soluble or water-dispersible polymer suspension / dispersion stabilizer used for suspension polymerization in an aqueous medium comprises (a) a partially saponified polyvinyl acetate having a degree of saponification of 85 mol% or more and 98 mol% or less. Dispersant, (b) saponification degree 35 mol%
Not less than 85 mol% of partially saponified polyvinyl acetate, methylcellulose, hydroxypropylmethylcellulose,
Carboxymethylcellulose, polyvinylpyrrolidone,
Polyacrylic acid, vinyl acetate-maleic acid copolymer, styrene-maleic acid copolymer, gelatin, starch and a dispersant comprising a combination of one or more selected from the group consisting of starch and polyethylene oxide,
And (c) a method for producing a vinyl chloride polymer, comprising a metal salt of at least one selected from the group consisting of sulfates, borates, nitrates and phosphates of alkali metals (claim) Item 1) is a dispersant (a)
0.005 to 100 parts by weight of the vinyl chloride monomer
To 0.2 parts by weight, the dispersant (b) is 0.001 to 0.2 parts by weight, (a) + (b) is 0.01 to 0.2 parts by weight,
2. The method for producing a vinyl chloride polymer according to claim 1, wherein (a) / ((a) + (b)) is 0.05 to 1, and a metal salt (c). ) Is 0.0005 to 0.05 with respect to 100 parts by weight of the vinyl chloride monomer.
The present invention relates to the method for producing a vinyl chloride polymer according to claim 1 or 2 which is parts by weight.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The dispersant of the present invention comprises (a) a dispersant composed of partially saponified polyvinyl acetate having a degree of saponification of 85 mol% to 98 mol%, and (b) a dispersant having a degree of saponification of 35 mol% or more. Less than 85 mol% of partially saponified polyvinyl acetate, methylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, polyacrylic acid, vinyl acetate-maleic acid copolymer, styrene-maleic acid copolymer, gelatin, starch and polyethylene A dispersant comprising one or more selected from the group consisting of oxides, and (c) sulfates, borates, nitrates of alkali metals,
And at least one metal salt selected from the group consisting of phosphates.

The degree of saponification of the dispersant (a) must be 85 mol% or more and 98 mol% or less. 85 mol%
When the amount is less than the above, it is difficult to achieve the initial purpose of increasing the bulk specific gravity, and when the amount exceeds 98% by mole, the function as a dispersant tends to be difficult to be exhibited.

On the other hand, the degree of saponification of the dispersant (b) needs to be 35 mol% or more and less than 85 mol%. 35
If it is less than mol%, the polymerization suspension droplets will be overdispersed,
If the polymerization system is unstable, and if the amount is 85 mol% or more, the protection of the droplets is reduced, and the polymerization system tends to be unstable.

In the present invention, the dispersant (a) particularly used is preferably from 0.005 to 0.2 part by weight, more preferably from 0.01 to 0.1 part by weight, based on 100 parts by weight of the vinyl chloride monomer. 1 part by weight, and similarly, the main dispersant (b) is preferably 0.001 to 0.2 part by weight, more preferably 0.005 to 0.1 part by weight. Also,
(A) + (b) is preferably 0.01 to 0.2 parts by weight.

When the dispersant (a) is less than 0.005 parts by weight, the bulk specific gravity does not increase, and the dispersant (b) is 0.005 parts by weight.
If the amount is less than 1 part by weight, or if (a) + (b) is less than 0.01 part by weight, the initial dispersing power of the monomer will be insufficient, and the amount of coarse particles of the resulting resin will increase. (A), (b), (a) +
If each of the components (b) exceeds 0.2 parts by weight, the dispersing power is so strong that the dispersion becomes so-called overdispersed, and the particle size distribution of the resin to be formed is widened and the number of fine particles increases.

In the present invention, there is no particular limitation on the timing of addition of the dispersant. However, in view of COD, it is preferable that the dispersant be adsorbed to the vinyl chloride polymer. It is preferable to end the process.

Further, regarding the dispersant (a) and the dispersant (b), (a) / ((a) + (b)) is 0.05 to 1, and the metal salt (c) is a vinyl chloride-based unit. It is preferable to use 0.0005 to 0.05 part by weight based on 100 parts by weight of the monomer.

At this time, if (a) / ((a) + (b)) is less than 0.05, the problem of clouding of the waste water after the post-polymerization treatment does not occur, but the bulk specific gravity does not tend to increase. There is. On the other hand, when the amount of the metal salt (c) is less than 0.0005 parts by weight, the wastewater becomes cloudy, and when the amount exceeds 0.05 parts by weight, the initial coloring and thermal stability of the molded article tend to decrease.

The dispersant (b) used in the present invention includes partially saponified polyvinyl acetate having a degree of saponification of 35 mol% or more and less than 85 mol%, methyl cellulose, hydroxypropyl methyl cellulose, carboxymethyl cellulose, polyvinyl pyrrolidone, polyacrylic acid, It is composed of one or more selected from the group consisting of vinyl acetate-maleic acid copolymer, styrene-maleic acid copolymer, gelatin, starch and polyethylene oxide. Among them, partially saponified polyvinyl acetate, hydroxypropylmethylcellulose, polyethylene oxide, methylcellulose, polyvinyl cellulose having a degree of saponification of 35 mol% or more and less than 85 mol% in terms of polymerization stability and thermal stability of the obtained resin. Pyrrolidone and the like are preferred.

The metal salt (c) used in the present invention is at least one metal salt selected from the group consisting of sulfates, borates, nitrates, and phosphates of alkali metals. , Sodium borate, sodium nitrate, sodium phosphate, potassium sulfate,
Examples include potassium borate, potassium nitrate, potassium phosphate and the like. Among them, sodium sulfate, sodium borate, sodium phosphate and the like are preferable from the viewpoint of the effect.

As the polymerization initiator in the present invention, conventionally known polymerization initiators can be used, and one or more of these initiators having a 10-hour half-life temperature of 30 to 65 ° C. are used. Is preferred. The amount of the initiator used varies depending on the type and polymerization temperature, but is preferably 0.005 to 0.5 part by weight per 100 parts by weight of the vinyl chloride monomer. As such a polymerization initiator, acetylcyclohexylsulfonyl peroxide, 2,4,4-
Trimethylpentyl-2-peroxyneodecanoate, di-2-ethylhexylperoxydicarbonate, di (2-ethoxyethyl) peroxydicarbonate, t-butylperoxypivalate, 3,5,5-trimethylhexa Organic peroxide initiators such as noyl peroxide, azobisisobutyronitrile, azobis-
Azo initiators such as 2,4, -dimethylvaleronitrile can be used, and these can be used alone or in combination of two or more.

The monomer used in the present invention is a monomer containing vinyl chloride as a main component, and specifically contains a vinyl chloride monomer alone or contains 70% by weight or more of a vinyl chloride monomer. It is a mixture of a vinyl chloride monomer and a copolymerizable monomer.

Examples of the monomer copolymerizable with the vinyl chloride monomer include vinyl esters such as vinyl acetate and vinyl propionate, α-olefins such as ethylene, propylene and isobutyl vinyl ether, 1-chloropropylene, Chlorinated olefins such as 2-chlorobutylene, (meth) acrylates such as methyl (meth) acrylate, maleic anhydride, acrylonitrile, styrene, vinylidene chloride and the like can be mentioned, and these can be used alone. Two or more kinds can be used in combination.

Further, a polymerization degree regulator, a chain transfer agent, and a pH, which are conventionally used for polymerization or copolymerization of a vinyl chloride monomer.
A regulator, a gelling agent, an antistatic agent, an emulsifier, a stabilizer, a scale inhibitor and the like and any of these preparation methods can also be used arbitrarily without any known technique, and the amount used is also a conventionally known method. Can be followed.

[0022]

EXAMPLES The present invention will be described more specifically with reference to the following Examples and Comparative Examples, which are not intended to limit the present invention. In addition, all the water of this example used ion-exchange water. PVA refers to partially saponified polyvinyl acetate.

The characteristic values of the obtained vinyl chloride polymer were measured by the following methods. (1) Bulk specific gravity Measured according to JIS K-6721. (2) Average particle size, particle size distribution The sieve analysis using a JIS standard wire netting resulted in a 50% passing diameter. (3) Transparency of wastewater The wastewater after the post-polymerization treatment was observed, and the evaluation results were shown as follows. ○: drainage is completely transparent, △: drainage is slightly white, ×: drainage is extremely white

Example 1 A 1500 L stainless steel polymerization machine equipped with a stirrer and a jacket was sealed, and the inside was evacuated with a vacuum pump.
2-ethylhexyl peroxydicarbonate at a concentration of 7
0.334 kg of isoparaffin solution dissolved at 0% by weight
Was charged. The amount of di-2-ethylhexyl peroxydicarbonate charged was 0.04 parts by weight based on 100 parts by weight of the vinyl chloride monomer. The stirrer equipped with a blue margin blade was operated after completing the charging of the vinyl chloride monomer, and the rotation speed was adjusted so that the peripheral speed of the stirring blade became 7.9 m / sec. Next, PVA having a degree of saponification of 80 mol% and an average degree of polymerization of 2,000 (this is referred to as PVA)
5.85 kg of a 3% by weight aqueous solution of 1%), 3.9 kg of a 3% by weight aqueous solution of PVA having a saponification degree of 98 mol% and an average degree of polymerization of 3400 (hereinafter referred to as PVA2), and an average degree of polymerization of 4500000 4.68% by weight of a 0.5% by weight aqueous solution of polyethylene oxide (hereinafter referred to as PEO)
kg with warm water at 60 ° C. At this time, the amount of warm water was adjusted so that the total amount of water was 702 kg. PV
The charged amounts of A1, PVA2 and PEO were 0.03 and 0.03 respectively with respect to 100 parts by weight of the vinyl chloride monomer.
2, 0.004 parts by weight. Further, 0.008 parts by weight of sodium sulfate as a metal salt was added to 100 parts by weight of the vinyl chloride monomer.

Further, after the internal temperature of the polymerization machine was raised to 57.0 ° C. by the external jacket, the internal temperature was maintained at this temperature. When the internal pressure of the polymerization machine dropped from the steady pressure by 1 kg / cm 2, the polymerization was stopped. The monomer was recovered and the polymerization was terminated. The obtained slurry was dewatered to confirm drainage, and the solid content was dried to obtain a vinyl chloride polymer, which was subjected to measurement of various characteristic values.

Example 2 The amount of PVA1 charged was 0.02 parts by weight based on 100 parts by weight of a vinyl chloride monomer. Instead of PVA2, the degree of saponification was 88 mol%, and the average degree of polymerization was 2,600. PV
A (this is referred to as PVA3) is a vinyl chloride monomer 10
Example 1 except that 0.03 parts by weight was used relative to 0 parts by weight.
Wastewater and a vinyl chloride polymer were obtained in the same manner as described above, and were subjected to measurement of various characteristic values.

Example 3 Drainage and a vinyl chloride polymer were obtained in the same manner as in Example 1 except that only PVA3 was used in an amount of 0.05 part by weight with respect to 100 parts by weight of the vinyl chloride monomer. The values were measured.

Example 4 0.04 parts by weight of PVA3 alone was used with respect to 100 parts by weight of a vinyl chloride monomer, and 30% by mole of methoxyl group, 10% by mole of hydroxypropoxyl group, and 2% by weight aqueous solution viscosity ( Drainage and vinyl chloride polymer were prepared in the same manner as in Example 1 except that 4000 mPa · s methylcellulose (MC1) was used at 0.01 part by weight with respect to 100 parts by weight of the vinyl chloride monomer. Obtained and subjected to measurement of various characteristic values.

EXAMPLE 5 Sodium borate was used as a metal salt in a vinyl chloride monomer 10
Drainage and a vinyl chloride polymer were obtained in the same manner as in Example 1 except that 0.005 parts by weight was used per 0 parts by weight, and used for measurement of various characteristic values.

Comparative Examples 1 to 4 Wastewater and a vinyl chloride polymer were obtained in the same manner as in Example 1 except that sodium sulfate was not used in Examples 1 to 4, and subjected to measurement of various characteristic values.

COMPARATIVE EXAMPLE 5 PVA1 was added to 100 parts by weight of a vinyl chloride monomer in an amount of 0.1%.
Except for using 008 parts by weight, in the same manner as in Comparative Examples 1 to 4,
Effluent and vinyl chloride polymer were obtained and used for measurement of various characteristic values.

[0032]

[Table 1]

When PVA having a high degree of saponification was used and sodium sulfate was not used, although the bulk specific gravity was high, the wastewater was white and cloudy (Comparative Examples 1 to 4). When the high saponification degree PVA was not used, the wastewater was transparent, but the bulk specific gravity did not increase (Comparative Example 5). On the other hand, it can be seen that in each of the examples of the present invention, the bulk specific gravity is high and the drainage is transparent.

As described above, the use of the method of the present invention provides a vinyl chloride polymer having a high bulk specific gravity and a clear drainage, and therefore the industrial value of the present invention is extremely high.

[0035]

According to the present invention, vinyl chloride having a high bulk specific gravity can be obtained without causing the problem of the method of using partially saponified polyvinyl acetate having a high degree of saponification as a dispersant, that is, without causing the problem of clouding of waste water. The production of a system polymer becomes possible.

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Claims (3)

[Claims] 1. A water-soluble or water-soluble polymer which is used for suspension polymerization of a vinyl chloride monomer or a mixture of a vinyl chloride monomer and a monomer copolymerizable with the vinyl chloride monomer in an aqueous medium. The dispersing polymer suspension stabilizer comprises: (a) a dispersant comprising partially saponified polyvinyl acetate having a saponification degree of 85 mol% or more and 98 mol% or less; (b) a saponification degree of 35 mol% or more and 85 mol % Of partially saponified polyvinyl acetate, methylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, polyacrylic acid, vinyl acetate-maleic acid copolymer, styrene-maleic acid copolymer, gelatin, starch and polyethylene oxide And a dispersant comprising a combination of one or more selected from the group consisting of: Genus sulfates, borates, nitrates,
And a metal salt comprising at least one metal salt selected from the group consisting of phosphates and phosphates. 2. The dispersant (a) is used in an amount of 0.005 parts by weight based on 100 parts by weight of a vinyl chloride monomer or a mixture of a vinyl chloride monomer and a monomer copolymerizable with the vinyl chloride monomer. ~
0.2 parts by weight, 0.001 to 0.2 parts by weight of dispersant (b), 0.01 to 0.2 parts by weight of (a) + (b), (a)
2. The method for producing a vinyl chloride polymer according to claim 1, wherein / ((a) + (b)) is 0.05 to 1. 3. The metal salt (c) is used in an amount of 0.0005 parts by weight based on 100 parts by weight of a vinyl chloride monomer or a mixture of a vinyl chloride monomer and a vinyl chloride monomer.
3. The method for producing a vinyl chloride polymer according to claim 1, wherein the amount is from 0.05 to 0.05 parts by weight.