JPH072765B2 - Polymer scale adhesion prevention method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for preventing polymer scale from adhering to the inner wall surface of a polymerization vessel or the like in the polymerization of a monomer having an ethylenic double bond.

[Conventional technology]

In a method of producing a polymer by polymerizing monomers in a polymerization vessel, it is known that the polymer adheres to the inner wall surface of the polymerization vessel as a scale. If polymer scale adheres to the inner wall surface of the polymerization vessel, etc., the yield of the polymer and the cooling capacity of the polymerization vessel will decrease, and the adhered polymer scale will peel off and enter the product, resulting in deterioration of the quality of the product polymer. Further, there are disadvantages such that a great amount of labor and time are required for removing the polymer scale.

Conventionally, as a method for preventing adhesion of polymer scale to the inner wall surface of the polymerization vessel, for example, a method of applying a polar compound, a dye, a pigment or the like to the inner wall surface (Japanese Patent Publication No. 30343/45,
-30835), a method of applying an aromatic amine compound (JP-A-51-50887), and a method of applying a reaction product of a phenolic compound and an aromatic aldehyde (JP-A-55-5431).
No. 7) etc. have been proposed.

These methods are advantageous for preventing adhesion of polymer scale in the polymerization of a vinyl halide monomer such as vinyl chloride or a monomer mixture containing the monomer as a main component and a small amount of a monomer copolymerizable therewith. Is.

[Problems to be Solved by the Invention]

However, when the monomer used for the polymerization is a monomer having another ethylenic double bond such as styrene, α-methylstyrene, acrylic acid ester and acrylonitrile, these monomers are Since the coating film formed by the anti-adhesion method has a remarkably large dissolving ability, part or all of the coating film is dissolved and lost, and as a result, the polymer scale adheres to the inner wall surface of the polymerization vessel. Cannot be effectively prevented. Particularly, in the case of a stainless steel polymerization vessel, there is a problem that polymer scale is likely to adhere.

Therefore, the present invention is not limited to vinyl halide monomers, in the polymerization of monomers having a wide range of ethylenic double bond, to effectively prevent the adhesion of the polymer scale to the inner wall surface of the polymerization vessel. It is to provide a method that can.

[Means for Solving the Problems]

The present inventors have found that the above object can be achieved by applying the two groups of specific compounds to the inner wall surface of the polymerization vessel in two steps.

That is, the present invention provides a method for preventing the adhesion of a polymer scale in the polymerization of a monomer having an ethylenic double bond in a polymerization vessel, which is intended to solve the above-mentioned problems. In advance, (a) a condensate of an aromatic compound is applied in advance to the other part in which the above-mentioned monomer comes into contact, and then (b) an anionic polymer compound and an amphoteric polymer are applied to the resulting coating film. The present invention provides a method for preventing adhesion of a polymer scale, which comprises performing the above-mentioned polymerization in a polymerization vessel coated with at least one selected from compounds.

As the condensate of the aromatic compound of the group (a) used in the present invention, for example, an aromatic amine compound and an aromatic nitro compound described in JP-B-60-30681 can be used in the presence of a condensation catalyst in an amount of 100 to 100%. A condensate obtained by reacting in the temperature range of 250 ° C, or a condensate obtained by basing the condensate with an alkali metal salt or an ammonium compound;
Approximately 25 described in Japanese Patent No. 561 and Japanese Patent Publication No. 60-54323
A linear or branched polyaromatic amine having a molecular weight of 0 or more; (1) a self-condensation product of a divalent or trivalent polyhydric phenol described in JP-B-62-3841, (2) 2
Or a condensation product selected from the group consisting of self-condensation products of polyhydric phenols having a valence of 3 or more and (3) self-condensation products of polyhydric naphthols; JP-B-60-5924
A reaction product of pyrogallol and an aldehyde, which contains a unit represented by the following general formula in the molecule described in JP-A-6 (In the formula, R is a divalent hydrocarbon group, p and q are 0 or 1); of pyrogallol or hydroxyhydroquinone represented by the following general formula described in JP-A-57-192413 and an aromatic aldehyde Condensate (In the formula, n represents 0 or an integer of 1 or more, R represents hydrogen or
C _{1 to} C ₁₀ alkyl group); an aromatic diamine and an aromatic quinone described in JP-A No. 61-7309, a solvent having a solubility parameter of 9.0 to 12.2, alone or in a mixed solvent, or against it. Examples thereof include a quinone-amine compound having an average molecular weight of 3000 or more, which is obtained by performing an addition reaction in a mixed solvent containing an equal amount or less of alcohol and then performing precipitation separation. These may be used alone or in combination of two or more.

Examples of the anionic polymer compound and amphoteric polymer compound in the group (b) include sulfomethyl compounds of polyacrylamide; polyacrylic acid; alginic acid, acrylamide-vinyl sulfonic acid copolymer, polymethacrylic acid, polystyrene sulfonic acid, and the like, or These alkali metal salts or ammonium salts; and anionic polymer compounds having a carboxyl group or a sulfonic acid group in the side chain such as carboxymethyl cellulose, and amphoteric polymer compounds such as glue, gelatin, casein, albumin and the like. To be These may be used alone or in combination of two or more. Among these, gelatin, casein, albumin, alginic acid and carboxymethyl cellulose are preferable.

In the method of the present invention, in order to form a coating film for preventing adhesion of the polymer scale on the inner wall surface of the polymerization vessel or the like, first, one or more condensates of the aromatic compound of the group (a) are polymerized. Inner wall surface and other parts where the monomer contacts during polymerization,
For example, it is applied to a stirring shaft, a stirring blade or the like. This coating operation is carried out by dissolving one or more condensates of aromatic compounds in a suitable solvent to prepare a coating solution, coating the coating solution on the inner wall of the polymerization vessel, etc., and then at room temperature to 100 ° C. It may be dried at the temperature of. As a solvent for dissolving the condensate of the aromatic compound, methanol, ethanol, propanol, butanol, 2-butanol, 2-methyl-1-
Propanol, 2-methyl-2-propanol, 3-methyl-1-butanol, 2-methyl-2-butanol,
Alcohol solvent such as 2-pentanol; n-hexane,
Aliphatic hydrocarbon solvent such as n-heptane; aromatic hydrocarbon solvent such as benzene, toluene, xylene; halogen such as methylene chloride, 1-chlorobutane, amyl chloride, dichloroethylene, 1,1,2-trichloroethane Chemical hydrocarbon solvents; ketone solvents such as acetone, methyl ethyl ketone, methyl isobutyl ketone; ester solvents such as methyl formate, ethyl formate, methyl acetate, methyl acetoacetate; ether solvents such as 4-methyldioxolane, ethylene glycol diethyl ether Examples of the solvent include furans, aprotic solvents, water and the like, and these are appropriately used alone or as a mixed solvent of two or more kinds.

The concentration of the condensate of the aromatic compound in the coating liquid is not particularly limited as long as the coating amount described below can be obtained, but is usually 0.
001 to 5% by weight is preferable. The dry coating amount of the obtained coating film is usually preferably 0.001 to 5 g / m ² .

Next, at least one selected from the anionic polymer compound and the amphoteric polymer compound of the group (b) is applied onto the coating film of the condensation product of the aromatic compound of the group (a) thus formed. . This coating operation is carried out, for example, by adding one or more of the required polymer compounds to a suitable solvent in an amount of about 0.01-5.0.
A coating solution may be prepared by dissolving the coating solution in a concentration of wt%, the coating solution may be applied to the coating surface of the condensate of the aromatic compound, and then dried at room temperature to about 100 ° C. It is necessary to form a coating film by sufficient drying. The temperature of the inner wall of the polymerization vessel during application (application temperature) is about room temperature to 100 ° C. As a solvent for dissolving at least one selected from anionic polymer compounds and amphoteric polymer compounds, water and organic solvents that are easily miscible with water, for example, alcohol solvents, ester solvents, ketone solvents, etc. These are appropriately used alone or as a mixed solvent of two or more kinds. The dry coating amount of the coating film comprising the anionic polymer compound and / or the amphoteric polymer compound of group (b) thus obtained is usually preferably 0.001 to 5 g / m ² .

In this way, after the two-step coating process is completed on the inner wall of the polymerization vessel and other portions where the monomer contacts during polymerization, the monomer having an ethylenic double bond is added to the polymerization vessel according to a conventional method. A polymerization initiator, other necessary polymerization medium and additives such as a dispersion aid of a monomer may be charged and polymerized.

As the monomer having an ethylenic double bond to which the method of the present invention is applied, for example, vinyl halide such as vinyl chloride, vinyl acetate, vinyl ester such as vinyl propionate, acrylic acid, methacrylic acid or their Examples thereof include esters or salts, maleic acid or fumaric acid, and their esters or anhydrides, diene-based monomers such as butadiene, chloroprene and isoprene, and styrene, acrylonitrile, vinylidene halide, vinyl ether and the like.

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

Therefore, as the additive substance to be added to the polymerization system, those usually used can be used without any restrictions. That is,
For example, suspension agents such as partially saponified polyvinyl alcohol, methyl cellulose and polyacrylate, solid dispersants such as calcium phosphate and hydroxyapatite, anionic emulsifiers such as sodium lauryl sulfate, sodium dodecylbenzene sulfonate and sodium dioctyl sulfosuccinate, sorbitan monolaurate. Rate, nonionic emulsifiers such as polyoxyethylene alkyl ether, fillers such as calcium carbonate and titanium oxide, tribasic lead sulfate, calcium stearate, dibutyltin dilaurate, stabilizers such as dioctyltin mercaptide, rice wax, stearic acid, etc. Lubricants, plasticizers such as DOP and DBP, chain transfer agents such as trichlorethylene and mercaptans, pH regulators, diisopropyl peroxydicarbonate, α, α'- Even in a polymerization system in which a polymerization catalyst such as zobis-2,4-dimethylvaleronitrile, lauroyl peroxide, potassium persulfate, cumene hydroperoxide, p-menthane hydroperoxide is present, the method of the present invention is a polymer. Adhesion of scale can be effectively prevented.

Polymerizations in which the process according to the invention is particularly preferably carried out are suspension or emulsion polymerizations of vinyl halides such as vinyl chloride or vinylidene halides, or of monomer mixtures based on them. Further, polystyrene in a polymerization vessel made of stainless steel, polymethylmethacrylate, beads of polymers such as polyacrylonitrile, production of latex, production of synthetic rubber such as SBR, NBR, CR, IR, IIR (these synthetic rubbers are usually It is also suitable for polymerization in which the ABS resin is produced).

〔Example〕

Next, the method of the present invention will be described with reference to Examples and Comparative Examples. In addition, in each of the following tables, the experiment numbers marked with * are comparative examples, and the other experiment numbers are examples of the present invention.

Production Example of Condensate of Aromatic Compound (1) Production of Condensate No. 1 1.00 mol of aniline, 0.310 mol of hydrochloric acid, 0.2 of nitrobenzene
A mixture of 27 mol and 0.103 mol of ferric chloride at 60 ° C
After heating for 6 hours at 180 ° C., the temperature was raised to 180 to 185 ° C. to distill off water, and the temperature was maintained for 15 hours to carry out the reaction. Aniline and nitrobenzene were distilled out along with water during the reaction. Distilled aniline and nitrobenzene were recovered and returned to the reactor. Next, the internal temperature of the reactor was raised to 200 ° C., and heating was performed at this temperature for 5 hours.

The obtained reaction mixture (melt) was poured into dilute sulfuric acid,
After heating at ℃ for 3 hours, it was filtered while hot to remove unreacted aniline. Next, after washing with water 5 to 6 times to remove hydrochloric acid,
It was dried to obtain a condensate.

(2) Production of Condensate No. 2 A mixture of 1.00 mol of m-phenylenediamine, 1.00 mol of hydrochloric acid and 0.83 mol of resorcinol was heated at 60 ° C. for 1 hour and then 300 ° C. while removing generated ammonia over 2 hours. The temperature was raised to. When the temperature reached 300 ° C., cooling was started and the temperature was returned to room temperature for 1 hour to obtain a solid condensate.

(3) Production of Condensate No. 3 Pyrogallol (3 mol) was dissolved in water (2), benzaldehyde (2 mol) and phosphoric acid (6 mol) were added, and the mixture was reacted at 100 ° C. for 4 hours.

The obtained reaction mixture was filtered, washed with hot water 5 to 6 times to remove excess phosphoric acid, and dried to obtain a condensate.

Example 1 Polymerization was carried out in the following manner using a stainless steel polymerization vessel having an internal volume of 1000 and equipped with a stirrer.

In each experiment, first, the condensate produced in the above Production Example was dissolved in methanol to a concentration of 0.5% by weight to prepare a coating liquid [coating liquid A]. It was applied to the contacting part, left at 50 ° C. for 15 minutes, dried and washed with water. Next, a coating liquid [coating liquid B] prepared by dissolving an anionic or amphoteric polymer compound in water was applied, dried and washed with water. Table 1 shows the condensate used in each experiment, the anionic or amphoteric polymer compound, the concentration of the coating liquid B, and the coating and drying conditions. However, the experiment
Nos. 1 to 3 are comparative examples in which the coating liquid is not applied or only the coating liquid A or B is applied.

After that, 400k of water was added to the polymerization vessel coated in this way.
g, 260 kg of styrene, 140 kg of acrylonitrile, 400 g of partially saponified polyacrylamide and 1.2 kg of α, α′-azobisisobutyronitrile were charged, and polymerization was carried out at 90 ° C. for 5 hours while stirring. After completion of the polymerization, 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 A coating solution A was applied to a stainless steel polymerization vessel with an internal volume of 100 and equipped with a stirrer in the same manner as in Example 1, and then a coating solution B was applied. Table 2 shows the condensate used in each experiment, the anionic or amphoteric polymer compound of the coating liquid B, the concentration of the coating liquid B, and the coating and drying conditions. However, in Experiment Nos. 16 to 18, the coating liquid was not applied or the coating liquid A was used.
Alternatively, it is a comparative example in which only one of B is applied.

Next, in a polymerization vessel coated in this way, 40 kg of water, 500 g of sodium oleate, 13 kg of polybutadiene latex (solid content 45%), 9.0 kg of styrene, 5.0 k of acrylonitrile.
g, t-dodecyl mercaptan 40 g, and cumene hydroperoxide 140 g were charged, and after raising the internal temperature to 65 ° C, glucose 200 g, ferrous sulfate 2 g and sodium pyrophosphate 100 g were charged, and then at 65 ° C for 5 hours with stirring. Polymerization was carried out.
After completion of the polymerization, the amount of polymer scale attached to the inner wall surface of the polymerization vessel was measured. The results are shown in Table 2.

[Effects of the Invention] According to the method of the present invention, it is possible to effectively prevent the adhesion of the polymer scale to the inner wall surface of the polymerization vessel or the like in the polymerization of a monomer having an ethylenic double bond, which has been difficult in the past. You can In particular, monomers with high solubility, such as styrene,
Adhesion of the polymer scale can be prevented even in the case of polymerization of a polymerization system containing α-methylstyrene, acrylic ester, acrylonitrile and the like. By performing the coating once in every batch or once in several batches, the polymerization vessel can be used repeatedly without adhering the polymer scale to the inner wall surface of the polymerization vessel.

Claims (1)

[Claims] 1. A method for preventing adhesion of a polymer scale in the polymerization of a monomer having an ethylenic double bond in a polymerization vessel, wherein the monomer contacts the inner wall surface of the polymerization vessel and the polymerization. First, (a) a condensate of an aromatic compound is applied to the other part in advance, and then the resulting coating film is applied with at least one selected from (b) an anionic polymer compound and an amphoteric polymer compound. A method for preventing adhesion of a polymer scale, which comprises performing the above-mentioned polymerization in a polymerization vessel thus obtained.