JPH01297404A - Production of vinyl chloride-based polymer - Google Patents

Abstract

PURPOSE:To completely prevent scales from depositing and obtain a product of excellent quality with high productivity by coating the inner wall, etc., of a polymerizer with a scale inhibitor and simultaneously adding a (thio) semicarbazone compound into an aqueous medium. CONSTITUTION:Suspension polymerization of vinyl chloride monomer or a mixture of vinylic monomers consisting essentially of the vinyl chloride is carried out in an aqueous medium in a polymerizer. In the process, the inner wall of the polymerizer and other parts thereof in contact with the monomers during the polymerization are coated with a scale inhibitor (e.g., dye, pigment, water-soluble high polymer, nitrite, iodic or aromatic amine compound) and a semicarbazone or thiosemicarbazone compound (e.g., formaldehyde semicarbazone or acetone thiosemicarbazone) expressed by formula I or II (A is O or S) R<1>, R<2> and R<3> are H or alkyl) in an amount of normally 1-100ppm based on the charged monomers is simultaneously added into the aqueous medium.

Description

Detailed Description of the Invention (Field of Industrial Application) The present invention is directed to a method for producing vinyl chloride polymers, and in particular, to completely prevent scale adhesion on the inner wall surface of a polymerization vessel, thereby achieving excellent quality. The present invention relates to a method for producing vinyl chloride polymers that can produce products with high productivity.

(Prior art) It is known that when a vinyl chloride polymer is subjected to suspension polymerization in an aqueous medium, the polymer adheres as scale to the inner wall surface of the polymerization vessel, and when this adheres, it is difficult to remove it. It requires a lot of labor and time, and as a result, productivity is significantly hindered, and the polymer yield and cooling capacity of the polymerization vessel decrease, as well as adhering polymer scale peeling off and contaminating the product. There was a problem in that the quality of the product itself deteriorated.

One way to prevent this adhesion is to apply polar compounds, dyes, pigments, etc. to the inner walls of the polymerization vessel and other parts of the polymerization vessel that come into contact with monomers during polymerization, such as baffles and stirring blades.
343, No. 45-30835), aromatic amine compounds (JP-A-51-50887), reaction products of phenol compounds and aromatic aldehydes (JP-A-55-543)
It is known to apply a scale inhibitor such as No. 17) in advance.

(Problem to be solved by the invention) However, these methods cannot completely prevent scale adhesion, and scale is particularly problematic at the gas-liquid interface, gas phase, and around the baffles in the polymerization reactor. there were.

An object of the present invention is to provide a method for completely preventing polymer scale from adhering to the inner wall of a polymerization vessel without impairing the quality of the obtained polymer product in a suspension polymerization method for vinyl chloride polymers. It is something.

Means for Solving CAM) The method for producing a vinyl chloride polymer according to the present invention involves suspension polymerization of a vinyl chloride monomer or a mixture of vinyl monomers mainly consisting of vinyl chloride in an aqueous medium. At the same time, a scale inhibitor is applied to the inner wall of the polymerization vessel and other parts of the polymerization vessel that come into contact with monomers during polymerization, and a scale inhibitor is added to the aqueous medium with the general formula % (where A is oxygen or sulfur). Each of the atoms, R1, R2, and R3 is at least one of a hydrogen atom or an alkyl group.
The gist of this is to add a semicarbazone or thiosemicarbazone compound represented by (indicating the species).

To explain this, the semicarbazone or thiosemicarbazone compound represented by the above general formula that is added to the aqueous medium in the present invention is a condensation product of semicarbazide or thiosemicarbazide and carbonyl, and specifically, the semicarbazone or thiosemicarbazone compound represented by the above general formula is a semicarbazone, methylsemicarbazone,
Examples include thiosemicarbazone, acetone thiosemicarbazone, and the like.

The amount of these compounds used is 1 to
It is preferably added at a rate of 1100 pp.

If this is less than 1 ppm, there is no effect in preventing scale adhesion (
, 100 pp or more is not preferable because it delays the polymerization reaction and affects the quality of the resulting polymer product.

On the other hand, scale inhibitors applied to the inner walls of the polymerization vessel and other parts of the polymerization vessel that come into contact with monomers during polymerization include conventionally well-known dyes, pigments, water-soluble polymers, nitrites, and nitrogen-containing aromatics. compounds, heterocyclic compounds, iodine compounds, pyrogallol derivatives, phenolic compounds, aromatic amine compounds, etc. Specific compounds of these include, for example,
No. 30343, No. -30835, No. -37988, No. 4
6-4753, -16084, -20821, 4g-29795, 49-2992, 51-1
No. 471, -1472, -21672, -2495
No. 3, No. -37306, No. -37308, No. 52-24
No. 070, No. 53-6023-6026, -219
No. 08, No. -28347, No. -28348, -3
No. 6509, -46235, No. 55-4327, -
No. 5523, No. 56-5442-5444, -224
No. 45, No. -22447, No. 57-31730, -3
No. 4286, No. -47922, No. -59243, No. 58
-11884.

-12893, -13564, -14444~14
No. 447, No. 59-1413, No. -31522, -3
No. 4721, No. 60-6361, No. 40444, -
Nos. 42245, -48522, -48523.

-59246, -59247, 61-842,
-843, -21247, -25730; JP-A-51-50887, JP-A-53-108187, JP-A-54
-50089, -101889, 55-2143
6, -54305, -54317, -73709
No., -98207, -112209, -15500
No. 1, No. -155002, No. 56-112903, No. 57-192413, No. -192414, -1957
No. 02, No. -198710, No. 5g-8709, -1
No. 1504, -61104, -69203, -10
No. 1103, -103503, -168607,
-180509 to 180511, -204006,
-210902, 59-11303, -7821
No. 0, No. -129207, No. -170102, -184
No. 202, No.-202201, No.-210902, No. 6
No. 0-20909, No.-47002, No.-71601,
-71614, -72902, -96603, -
No. 233103, No. 61-7309.

-31406, -34006, -51001, -
Examples include those described in publications such as No. 51002.

In addition to vinyl chloride monomers, monomers that can be applied to the polymerization in the method of the present invention include vinyl chloride monomers and mixtures of vinyl monomers copolymerizable with vinyl chloride (vinyl chloride is
Comonomers copolymerized with vinyl chloride include vinyl esters such as vinyl acetate and vinyl propionate; acrylic esters or methacrylic esters such as methyl acrylate and ethyl acrylate; Examples include olefins such as ethylene and propylene; maleic anhydride; acrylonitrile; styrene; and vinylidene chloride.

When a dispersant is used in this suspension polymerization, the type thereof is not particularly limited, and any commonly used dispersant may be used. Examples include methylcellulose, hydroxyethylcellulose, hydroxypropylcellulose,
Water-soluble cellulose ethers such as hydroxypropyl methylcellulose; partially saponified polyvinyl alcohol; acrylic acid polymers; water-soluble polymers such as gelatin; oil-soluble such as sorbitan monolaurate, sorbitan triolate, glycerol tristearate, and ethylene oxide propylene oxide block copolymers Emulsifiers: Water-soluble emulsifiers such as polyoxyethylene sorbitan monolaurate, polyoxyethylene glycerol oleate, sodium laurate, etc. are used, and these may be used singly or in combination of two or more.

The polymerization initiator may also be one conventionally used in vinyl chloride polymerization, such as peroxydicarbonate such as diisopropyl peroxydicarbonate, di-2-ditylhexylhexyl oxydicarbonate, and jetoxyethyl peroxydicarbonate. Carbonate compounds: perester compounds such as t-butylperoxyneodecanate, t-butylperoxypivalate, t-hexylperoxypivalate, α-cumylperoxyneodecanate; acetylcyclohexylsulfonyl peroxide, 2. 4
．． Peroxides such as 4-trimethylpentyl-2-peroxyphe7noxyacetate, 3,5.5-)-limethylhexanoyl peroxide; azobis-2,4-dimethylvaleronitrile, azobis(4-methoxy-2 ,4
-dimethylvaleronitrile); and potassium persulfate, ammonium persulfate, hydrogen peroxide, etc., which can be used alone or in combination of two or more.6 Polymerization in the method of the present invention Other terms and conditions.

The method of charging the aqueous medium, vinyl chloride monomer, other vinyl monomers, suspending agent, etc. to the polymerization vessel can be carried out in the same manner as before, depending on the charging ratio, polymerization temperature, etc. The polymerization conditions may also be similar.

Further, if necessary, polymerization regulators, chain transfer agents, pH adjusters, gelling improvers, antistatic agents, etc., which are appropriately used in vinyl chloride polymerization, may be added.

(Example) A specific embodiment of the present invention will be explained below using Examples and Comparative Examples, but the present invention is not limited thereto.

Example 1 A toluene solution of monoaminomononitroazobenzene was uniformly applied to nine inner wall blades and baffles of a stainless steel autoclave having an internal volume of 100Q and dried. Next, 60 kg of pure water was charged into this autoclave, and 30 g of 9-partly saponified polyvinyl alcohol dissolved in advance in pure water IQ was charged. To this were charged 0.6 g of the semicarbazone or thiosemicarbazone compound shown in the table and 12.6 g of di-2-ethylhexyl peroxydicarbonate as a polymerization initiator. Thereafter, the autoclave was degassed using a vacuum pump until the internal pressure reached 1,700 mmHg.

After degassing, 30 kg of vinyl chloride monomer was charged, and then heating was started, and polymerization was carried out at 57°C. Internal pressure is 6.
The reaction was stopped when the weight decreased to 0 kg/ff1G, unreacted monomers were collected, and the polymer slurry was extracted. After washing the inside of the autoclave with pure water and drying the inner wall surface, the state of scale adhesion was observed, and the amount of polymer adhering as scale was measured.

Example 2゜C,1, Direct Blue 1, IK, C,1, Basic Blue 12, 0.2g, ion exchange water 10100
An aqueous solution containing 1.7 g of phytic acid dissolved in O was applied to the inner wall, blades, and baffle of the autoclave, dried at 50° C. for 10 minutes, and then washed with water. after that,
In the same manner as in Example 1, semicarbazone or thiosemicarbazone compound was added and polymerization was carried out, and the state of scale adhesion was observed by WA, and the amount of polymer adhering as scale was measured.

Comparative Example 1゜Polymerization was carried out in the same manner as in Example 1 except that semicarbazone or thiosemicarbazone compound was not added, and measurements were carried out.

Comparative Example 2 Polymerization was carried out and measured in the same manner as in Example 2, except that no semicarbazone or thiosemicarbazone compound was added.

The results of each measurement are shown in the table below.

(Reference: g/m) (Effects of the Invention) According to the present invention, scale does not adhere to the inner wall surface of the polymerization vessel or other parts of the polymerization vessel with which monomers come into contact during polymerization, resulting in excellent results. Quality products can be obtained with high productivity.

Claims (1)

[Claims] 1. When a vinyl chloride monomer or a mixture of vinyl monomers mainly composed of vinyl chloride is subjected to suspension polymerization in an aqueous medium, the inner wall of the polymerization vessel and the monomer during polymerization are In addition to applying a scale preventive agent to other parts of the polymerization vessel that come in contact with the body, the aqueous medium contains general formulas ▲mathematical formulas, chemical formulas, tables, etc.▼, or NH_2CANH・N=CHR＾3 (where A is Oxygen or sulfur atom, R^1, R^2, R
A method for producing a vinyl chloride polymer, which comprises adding a semicarbazone or thiosemicarbazone compound represented by ^3 each representing at least one of a hydrogen atom or an alkyl group. 2. The scale inhibitor is selected from the group consisting of dyes, pigments, water-soluble polymers, nitrites, nitrogen-containing aromatic compounds, heterocyclic compounds, iodine compounds, pyrogallol derivatives, phenolic compounds, and aromatic amine compounds. at least 1
The method for producing a vinyl chloride polymer according to claim 1, which is a seed compound.