JPH0247103A - Method for preventing polymer scale adhesion - Google Patents

Abstract

PURPOSE:To effectively prevent polymer scale from depositing on the wall of a polymerizer in which an ethylenically unsaturated monomer is polymerized by applying an aqueous coating solution containing an anionic dye and a cationic dye. CONSTITUTION:In polymerizing an ethylenically unsaturated monomer such as vinyl chloride, an aqueous coating solution containing a water-soluble anionic dye (A) (e.g., C.I. Acid Black 2) and a water-insoluble cationic dye (B) (e.g., C.I. Solvent Black 3) and having a controlled pH <=7 is applied to the inside wall of the polymerizer and the areas with which the monomer is in contact during the polymerization, such as impellers, and dried to form a film which can prevent scale deposition. The concentration of the dyes in the coating solution is desirably 0.05-2wt.%, and the A to B weight ratio is desirably 100/3-100/100. The coating amount is usually about 0.001-5g/m<2> (in a dry state).

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a method for preventing the adhesion of polymer scale, particularly in the polymerization of monomers having ethylenic double bonds. The present invention relates to a method that can effectively prevent adhesion.

[Conventional technology]

BACKGROUND ART In a method of producing a polymer by polymerizing monomers in a polymerization vessel, there is a known problem that the polymer adheres as scale to the inner wall surface of the polymerization vessel. When polymer scale adheres to the inner wall surface of a polymerization vessel, a great deal of effort and time is required to remove the polymer scale. Furthermore, there are disadvantages such as a decrease in the yield of the polymer, a decrease in the cooling capacity of the polymerization vessel, and a deterioration in the quality of the product polymer due to the adhering polymer scale peeling off and contaminating the product.

Conventionally, as a method for preventing polymer scale from adhering to the inner wall surface of a polymerization vessel, for example, a method of applying polar compounds, dyes, pigments, etc. to the inner wall surface (Japanese Patent Publication Nos. 45-30343 and 45-30835) has been used. , a method of applying an aromatic amine compound (Japanese Unexamined Patent Publication No. 51-50887), a method of applying a reaction product of a phenol compound and an aromatic aldehyde (Japanese Unexamined Patent Publication No. 55-54317), etc. are known.

These methods are effective in preventing the adhesion of polymer scale in the polymerization of vinyl halide monomers such as vinyl chloride, or monomer mixtures mainly composed of vinyl chloride and containing small amounts of monomers that can be copolymerized with these monomers. It is.

[Problem to be solved by the invention]

However, the monomers subjected to polymerization have other ethylenic double bonds, such as styrene, α-methylstyrene, acrylic ester, acrylonitrile, and the like.

In the case of monomers, these monomers have a significantly large dissolving ability for the coating film formed by the above-mentioned adhesion prevention method, so that part or all of the coating film is dissolved and lost; As a result, it is not possible to effectively prevent polymer scale from adhering to the inner wall surface of the polymerization vessel. This scale adhesion is particularly likely to occur in stainless steel polymerization vessels.

Therefore, the purpose of the present invention is to effectively prevent the adhesion of polymer scale to the inner walls of the polymerization vessel, etc., in the polymerization of not only halogenated vinyl monomers but also a wide range of monomers having 5 ethylenic double bonds. Our goal is to provide a way to do so.

[Means to solve the problem]

The present invention solves the above problems and provides a method for preventing the adhesion of polymer scale during the polymerization of a monomer having an ethylenic double bond in a polymerization vessel, the method comprising: The polymerization is performed in a polymerization vessel in which an aqueous coating solution containing a water-soluble anionic dye and a water-insoluble cationic dye and whose pH is adjusted to 7 or less is applied to other parts that the monomer comes into contact with and dried. A method for preventing polymer scale adhesion is provided.

Examples of the water-soluble anionic dye used in the present invention include sulfonic acid type dyes, carboxylic acid type dyes, and dyes having amphoteric properties of sulfonic acid and carboxylic acid.

Sulfonic acid type dyes include, for example, C,1, Acid Yellow 38; C,1, Food Yellow 3; C,1, Reactive Yellow 3; C,1, Direct Orange 2.
．． 10.26; C, 1, Acid Red 18.52
, 73.80 iC, 1, Direct Red 3L1B
6.92; C, 1, Direct Violet 1
, 22; C, 1, acid violet 11.78;
C,1, Mordant Violet 5; C,I.

Direct Blue 1. 6.71.86.106 i
c, I, reactive blue 2. 4.18;C,1,
Acid Blue 1, 40.59, 113, 116, 15
8, C, 1, Acid Black 1.2.124
:C, I, Direct Black 19.32.38°77
; C1, Solbilized Butt Black 1: C, I.

Fluorescent brightening agent 30°32
iC, 1, acid orange 3. 7 ic, 1. Direct Green 1st grade is mentioned.

In addition, examples of carboxylic acid type dyes and sulfonic acid type and carboxylic acid type amphoteric dyes include C, 1,
Direct Yellow 1ic, 1. direct red 1
iC, 1, Mordand Black 5; C, I.

Azoic Brown 2iC, 1, Direct Brown 1
, 37. 101; C, 1, Direct Green 26; C, I.

Acid Red 87; C, 1, Mordant Yellow 26
; C,1, Direct Orange 97, and the like.

These water-soluble anionic dyes may be used alone or in combination of two or more.

Examples of water-insoluble cationic dyes used in the present invention include Solvent Yellow 2.6, 14°15, 16
．． 19. 21. 33. 56. 61. 80;
Solvent Orange 1.2.14.37.40.44,
45; Solvent red 1, 3, 8° 23.24, 25
,27,30,49,81,82.83,84,100
, 121 ; Solvent violet 8, 13, 14,
21.27; Solvent Blue 2.11, 12, 25.
35, 36° 55.73; Solvent Green 3; Solvent Brown 3.5.20, 37; Solvent Black 3, 5, 7, 22, 23; Acid Black 123;
Disperse Yellow 1.3, 4.5, 7゜23.31
．． 33, 42.49, 50.51.54.56, 60,
61, 64. 66. 71, 72° 76.78, 79; Disperse orange 1.3° 5.11, 13, 20, 2
1, 30.32, 41° 43.45, 46, 49.50
, 51 ; Dispersed thread 1, 4, 5, 7, 11,
12,13°15.17,43,52.53.54,5
5,56.58,59,60,65,72.73,74
゜75.76.80, 82.84.88, 90.91.
92.97,99,100,101,103゜104,
113,116,117,122,125.126,1
27,128,129. Disperse violet 1,
4,8.10.18.23゜24.26.2B, 30,
33.37.38; Disperse Blue 1.3.5.6
,7,20,26.27,43,44,52.54,5
5,56°5B, 60.61.62, 64, 72, 73
．． 75.79, 81, 85, 87, 88, 90.92°94.97, 98, 99. 103, 104, 105.
106.108i Disperse Brown 3°5; Disperse Black 1.2.10.26°27.2B, 29
, 30, 31 ; Fluorescendo Brightening Age End 170, 135, 162. 163, 164, 12
1,172.91 etc. are mentioned.

These water-insoluble cationic dyes can be used alone or in combination of two or more.

In the method of the present invention, in order to form a coating film that prevents polymer scale from adhering to the inner wall surface of a polymerization vessel, the water-soluble anionic dye and the water-insoluble cationic dye are included, and the pH is 7 or less, preferably 1 An aqueous coating solution adjusted to .5 to 3.5 is prepared and applied to the inner wall surface of the polymerization vessel and other parts that come into contact with the monomer during polymerization, such as the stirring shaft and stirring blades. This aqueous coating solution can be prepared by mixing an aqueous solution of a water-soluble anionic dye and an organic solvent solution of a water-insoluble cationic dye dissolved in a small amount of a suitable organic solvent.

The organic solvent for dissolving the water-insoluble cationic dye is preferably one that is easily miscible with water, such as methanol, ethanol, propatool butanol, 2-methyl-1-propateol, 2-butanol, 2-methyl -2-propanol, 3-methyl-1-butanol, 2
- Alcohols such as methyl-2-butanol, 2-pentanol, and 2-pentanol; Ketones such as acetone, methyl ethyl ketone, and methyl isobutyl ketone; Ethers such as 4-methyldioxolane and ethylene glycol diethyl ether; Methyl formate, Esters such as ethyl formate, methyl acetate, and methyl acetoacetate; Furans such as tetrahydrofuran, furfural, furfuryl alcohol, and tetrahydrofurfuryl alcohol; Aprotic properties such as acetonitrile, formamide, dimethylformamide, dimethyl sulfoxide, and N-methylpyrrolidone Examples include solvents. These may be used alone or in combination of two or more.

The total concentration of the water-soluble anionic dye and the water-insoluble cationic dye in the aqueous coating solution is not particularly limited as long as the amount of coating described below can be obtained, but is usually preferably 0.01 to 5.
% by weight, more preferably 0.05 to 2% by weight.

In addition, the weight ratio of water-soluble anionic dye/water-insoluble cationic dye in the aqueous coating solution is usually 10010.1 to 100.
/1000, more preferably 100/3 to 100/100. If this weight ratio is too small, the dye will coagulate and precipitate, making it impossible to obtain a uniform coating film.If this weight ratio is too large, even if the coating liquid is applied to the inner wall surface of the polymerization vessel and dried, it will not be possible to apply it by washing with water. There is a risk that the membrane will dissolve.

The pH of the aqueous coating solution can be adjusted, for example, by any of the methods described below.

■ A method of mixing an aqueous solution of a water-soluble anionic dye to which a pH adjuster has been added in an amount such that the pH of the coating solution is 7 or less, and an organic solvent solution of a water-insoluble cationic dye. A method of mixing an organic solvent solution of a water-insoluble cationic dye with an amount of pH moderator added and an aqueous solution of a water-soluble anionic dye ■After mixing an organic solvent solution of a water-insoluble cationic dye and an aqueous solution of a water-soluble anionic dye , Method of Adding a pH Adjuster Examples of pHgP1 moderators used include sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, carbonic acid, perchloric acid, molybdic acid, tungstic acid, formic acid, acetic acid, oxalic acid, lactic acid, and maleic acid. , glycolic acid, thioglycolic acid, phytic acid, etc. These can be conveniently prepared in advance as an aqueous solution when added for pH adjustment.

Further, the weight ratio of water/organic solvent in the aqueous coating solution is not particularly limited as long as a uniform coating film is obtained, but is usually 10
0/1~100/30, further 100/3~100
/10 is preferable.

In the method of the present invention, the aqueous coating liquid prepared as described above is applied to the inner wall surface of the polymerization vessel, etc., and then dried to form a coating film. Methods for applying an aqueous coating liquid to the inner wall surface of a polymerization vessel and drying include, for example, a method in which air heated to an appropriate temperature is blown onto the coated surface after coating to dry it; Pre-apply 30～
Any method may be used, such as heating to about 90° C., directly applying an aqueous coating liquid to the heated inner wall surface of the polymerization vessel, and drying. After drying, it may be washed with water if necessary.

The amount of aqueous coating liquid applied to the inner wall of the polymerization vessel, etc. after drying is usually 0.0
It is about 0.01 to 5 g/a.

After applying the aqueous coating solution to the inner wall surface of the polymerization vessel and other parts that come into contact with monomers during polymerization to form a coating film as described above, apply the ethylene film to the polymerization vessel in the usual manner. A monomer having a bond, a polymerization initiator, and other necessary polymerization media and additives, such as a monomer dispersion aid, may be charged and polymerized.

Monomers having an ethylenic double bond to which the method of the present invention is applied include, for example, vinyl halides such as vinyl chloride, vinyl esters such as vinyl acetate and vinyl propionate, acrylic acid, methacrylic acid, and the like. esters or salts of maleic acid or fumaric acid and their esters or anhydrides, diene monomers such as butadiene, chlorobrene, and isoprene, as well as styrene, α-methylstyrene, acrylic esters, acrylonitrile, vinylidene halides, and vinyl ethers. Examples include.

The method of the present invention is effective regardless of the material of the inner wall of the polymerization vessel, such as stainless steel, lined glass, etc.

Further, the method of polymerization to which the method of the present invention is applied is not particularly limited, and any polymerization method such as suspension polymerization, emulsion polymerization, solution polymerization, and bulk polymerization is effective.

Therefore, any commonly used additives added to the polymerization system can be used without any restrictions. That is,
For example, suspending agents such as partially saponified polyvinyl alcohol, methyl cellulose, and polyacrylate; solid dispersing agents such as calcium phosphate and hydroxyapatite; anionic emulsifiers such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, and sodium dioctyl sulfosuccinate; fillers such as calcium carbonate and titanium oxide, stabilizers such as tribasic lead sulfate, calcium stearate, dibutyltin dilaurate, dioctyltin mercaptide, rice wax, stearic acid, etc. Lubricant, DOP, DBP
plasticizers such as trichlorethylene, chain transfer agents such as mercaptans, pHtPI adjusters, diisopropyl peroxydicarbonate, α,α'-azobis-2゜4-
dimethylvaleronitrile, lauroyl peroxide,
Potassium persulfate, cumene hydroperoxide, p-
Even in a polymerization system in which a polymerization catalyst such as menthane hydroperoxide is present, the method of the present invention can effectively prevent the deposition of polymer scale.

Polymerization in which the method of the present invention is particularly suitably carried out is, for example, suspension polymerization or emulsion polymerization of vinyl halides such as vinyl chloride, vinylidene halides, or monomer mixtures mainly containing these. In addition, polymer beads such as polystyrene, polymethyl methacrylate, and polyacrylonitrile are mainly used in stainless steel polymerization vessels.
Latex manufacturing, 5BRSNBR, CRS I R,
, IIR (these synthetic rubbers are usually produced by emulsion polymerization), and polymerization for producing ABS resins.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. In each table below, the experiment Nα marked with * is a comparative example, and the other experiments are examples of the present invention.

Example 1 In each experiment, (a) an aqueous solution of a water-soluble anionic dye and (b) an organic solvent solution of a water-insoluble cationic dye were mixed, and (a) a water-soluble anionic dye and (b) water in the coating solution were mixed. An aqueous coating solution was prepared in which the total content including the insoluble cationic dye was 0.1% by weight, and phytic acid was added to adjust the pH. This aqueous coating liquid has an internal volume of 100I! ,
Apply to the inner wall of a stainless steel polymerization vessel with a stirrer, the stirrer, and other parts that come into contact with the monomer during polymerization, and heat at 50°C for 1 hour.
After drying for 5 minutes, it was washed with water. However, experiment Nα1~
6 is a comparative example in which no aqueous coating solution was applied, or an aqueous coating solution that did not contain either (a) a water-soluble anionic dye or (b) a water-insoluble cationic dye, or an aqueous coating solution with a pH of more than 7 was applied. (a) Water-soluble anionic dye and (b) water-insoluble cationic dye used on each side, weight ratio of (a)/(b) in the aqueous coating solution, and (b) organic solvent in which the water-insoluble cationic dye was dissolved. The types, the weight ratio of water/organic solvent in the aqueous coating solution, and the pH of the aqueous coating solution are shown in Table 1.

Next, in the polymerization vessel coated in this manner, 26 kg of vinyl chloride, 52 kg of pure water, 26 g of partially saponified polyvinyl alcohol, and 8 g of α,α'-dimethylvaleronitrile were placed.
g was charged and polymerized at 58°C for 10 hours while stirring.

After the polymerization was completed, the amount of polymer scale attached to the inner wall surface of the polymerization vessel was measured. The results are shown in Table 1.

Example 2 In each experiment, (a) an aqueous solution of a water-soluble anionic dye dissolved in 95 parts by weight of water, and (b) an aqueous solution of a water-soluble anionic dye dissolved in 5 parts by weight of methanol.
After mixing with a solution containing a water-insoluble cationic dye,
p) A regulator was added to adjust the pH to 2.5 to prepare an aqueous coating solution. At this time, the weight ratio of (a) water-soluble anionic dye and (b) water-insoluble cationic dye in the aqueous coating solution was adjusted as shown in Table 2. Table 2 shows the dyes and pH adjusters used in each experimental strain. This aqueous coating solution was applied to the inner wall surface of a stainless steel polymerization vessel with an internal volume of 1,001 liters, a stirrer, and other parts that would come into contact with the monomer during polymerization.
After drying at °C for 10 minutes, it was washed with water. However, in Experiment Sake 29, no coating liquid was applied.

Next, in the polymerization vessel coated in this manner, 24 kg of styrene, acrylonitrile SB, 40 g of pure water, hydroxyapatite O, skg, 16 g of sodium dodecylbenzenesulfonate, and 1 g of t-dodecylmercaptan were added.
60 g and 160 g of benzoyl peroxide were charged and reacted at 80° C. for 10 hours with stirring to produce a polymer.

After the polymerization was completed, the amount of polymer scale attached to the inner wall surface of the polymerization vessel was measured. The results are shown in Table 2.

Example 3 In each experiment, an aqueous coating solution was applied to the inner wall surface of a stainless steel polymerization vessel with an internal volume of 10,042 mm and equipped with a stirrer and other parts that come into contact with the monomer during polymerization, and the heating and drying conditions shown in Table 3 were applied. After heating and drying under certain conditions, it was washed with water. However, in Experiment No. 54, no aqueous coating liquid was applied. The aqueous coating liquid used in each experiment was the same as that used in Experiment Nα in Examples 1 and 2 shown in Table 3.

Next, 27 kg of polybutadiene latex (solid content concentration: 50% by weight) was placed in the polymerization vessel coated in this way.
, 40 kg of pure water, 7 kg of styrene, 3 kg of acrylonitrile, 62.5 g of t-dodecylmercaptan, and 70 g of potassium persulfate were charged and reacted at 50°C for 10 hours to produce a polymer.

After the polymerization was completed, the amount of polymer scale attached to the inner wall surface of the polymerization vessel was measured. The results are shown in Table 3.

Table 3 Example 4 In each experiment, an aqueous coating solution was applied to the inner wall surface of a stainless steel polymerization vessel with an internal volume of 202 mm and other parts that would come into contact with the monomer during polymerization, and heated at 50°C for 15 minutes. ,
After drying, it was washed with water. The aqueous coating liquid used in the experiment was the same as that used in Experiment Nα in Examples 1 and 2 shown in Table 4.

Next, 1.3-
Butadiene 3. 7kg, styrene 1.3kg.

9 kg of pure water, 225 g of sodium dodecylbenzenesulfonate, 14 g of t-dodecyl mercaptan and 15 g of potassium peroxide were charged and heated at 50°C with stirring.
A polymer was produced by polymerizing for 2 hours.

After the polymerization was completed, the amount of polymer scale attached to the inner wall surface of the polymerization vessel was measured. The results are shown in Table 4.

Table 4 Example 5 Each experiment was carried out in the same manner as in Example 1, except that the aqueous coating liquid shown in Table 5 was used, and the heating and drying after application of this aqueous coating liquid were performed under the conditions shown in Table 5. After polymerization, remove the produced polymer, wash the interior of the polymerization vessel with water, repeat the coating process and polymerization in the same manner as above, and ensure that the amount of scale attached does not exceed Ig/rW. The number of times of polymerization that can be performed (number of times of scale prevention) was investigated. However, Experiment 82 is a comparative example in which no coating liquid is applied, and the water-based coating liquid used in each experiment is shown in Table 5.
This was the same as that used in the experimental strainer in Example 1 shown in . The results are shown in Table 5.

Adhesion to surfaces etc. can be effectively prevented.

In particular, it is possible to prevent the adhesion of polymers even in the case of polymerization of polymer systems containing monomers with high solubility, such as styrene, α-methylstyrene, acrylic esters, and acrylonitrile. By performing the coating treatment on the inner wall surface of the polymerization vessel, etc., in every batch or once every few batches, the polymerization vessel can be used repeatedly without the polymer adhering to the inner wall of the polymerization vessel. In addition, since the coating liquid used is an aqueous solution containing only a small amount of organic solvent, there is little toxicity due to the organic solvent and high safety is achieved.

Agent Patent Attorney Comrade Iwamiya 〔Effect of the invention〕

Claims (1)

[Claims] A method for preventing the adhesion of polymer scale during the polymerization of a monomer having an ethylenic double bond in a polymerization vessel, the method comprising the steps of: Preventing the adhesion of polymer scale in which the polymerization is performed in a polymerization vessel in which an aqueous coating solution containing a water-soluble anionic dye and a water-insoluble cationic dye and adjusted to pH 7 or less is applied in advance to other parts of the polymerization vessel and dried. Method.