JPH0615565B2 - 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, 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 used to prevent 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. It is valid.

[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 adhesion prevention 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. In particular, when a stainless steel polymerization vessel is used, there is a problem that polymer scale is likely to adhere.

Therefore, the present invention is not limited to vinyl halide monomers,
It is an object of the present invention to provide a method capable of effectively preventing the adhesion of polymer scale to the inner wall of a polymerization vessel or the like in the polymerization of a monomer having a wide range of ethylenic double bonds.

[Means for Solving the Problems]

MEANS TO SOLVE THE PROBLEM This invention is a method of preventing adhesion of a polymer scale in superposition | polymerization of the monomer which has an ethylenic double bond in a polymerization machine as a 1st method in order to solve the said subject, Comprising: To the inner wall surface and other portions where the monomer contacts during polymerization, first, (a) a coating solution having an anionic dye and having a pH of 7 is applied in advance, and then the obtained coating film (b) It is intended to provide a method for preventing adhesion of a polymer scale, which comprises performing the above-mentioned polymerization in a polymerization vessel coated with a cationic polymer compound.

In the first method of the present invention, first, an anionic dye is dissolved or dispersed in an appropriate solvent on the inner wall surface of the polymerization vessel and other portions with which the monomer contacts during the polymerization, and pH 7
A coating solution (hereinafter referred to as "coating solution A") whose pH is preferably adjusted to 6 or less is applied below.

Examples of the anionic dye that is dissolved or dispersed in the coating liquid A include CI Acid Yellow 38; CI Acid Red 18, 52, 73, 80, 87; CI Acid Violet 1
1,78; CI Acid Blue 1,40,59,113,116,12
0,158; CI Acid Orange 3,7; CI Acid Black 1,2,124; CI Direct Orange 2,10,2
6,97; CI Direct Red 1,31,92,186; CI Direct Violet 1,22; CI Direct Blue 1,6,71,86,106; CI Direct Black 2,1
9, 32, 38, 77; CI Direct Green 1, 26; CI
Direct Yellow 1; CI Direct Brown 1,3
7, 101; CI Food Yellow 3; CI Reactive Yellow 3; CI Reactive Blue 2, 4, 18; CI Mordant Violet 5; CI Modulant Black 5; C.
I. Mordant Yellow 26; CI Fluorescent Brightening Agent 30, 32; CI Solved Bat Black 1; CI Azoic Brown 2 and the like.

The anionic dye is not particularly limited in the coating liquid A of the present invention as long as the coating amount described later can be obtained, but it is usually 0.01
-5% by weight, preferably 0.05-2% by weight.

As the solvent used for preparing the coating liquid A, water and a solvent miscible with water, for example, methanol, ethanol, n
-Alcohol solvents such as propyl alcohol; ketone solvents such as acetone and methyl ethyl ketone; ester solvents such as methyl formate and methyl acetate; aprotic solvents such as dimethylformamide, dimethyl sulfoxide, acetonitrile and the like. These are 1 type alone or 2
It can be used as a mixed solvent of two or more species.

Also used to adjust the pH of coating solution A to 7 or less
As the pH adjuster, for example, sulfuric acid, hydrochloric acid, phosphoric acid, nitric acid, carbonic acid, perchloric acid, molybdic acid, tungstic acid,
Formic acid, acetic acid, oxalic acid, lactic acid, maleic acid, glycolic acid, thioglycolic acid, phytic acid, and the like, and acid salts thereof and the like can be mentioned, preferably sulfuric acid, phosphoric acid, nitric acid, molybdic acid, lactic acid, glycolic acid. , Thioglycolic acid, phytic acid and their acid salts. If this pH adjuster is added in advance as an aqueous solution, the
It is convenient for pH adjustment. By adjusting the pH of the coating liquid A to 7 or less, a film of water-insoluble anionic dye can be formed on the metal surface such as the inner wall of the polymerization vessel.

The coating solution A prepared as described above is applied to the inner wall surface of the polymerization vessel and other portions where the monomer contacts during the polymerization, such as a stirring shaft and a stirring blade, and then the coating surface is at room temperature to 100 ° C.
A coating film can be formed by sufficiently drying at a moderate temperature. In addition, the inner wall surface of the polymerization vessel is pre-set to 30 to 100 ° C.
It is also possible to form the coating film by applying the coating liquid A after heating to a certain degree and drying at the same time as the coating. After forming this coating film, it can be washed with water as required.

Coating of the thus coating solution A obtained is usually dried coating amount of 0.001 g / m ² or more, particularly about 0.5 to 2 g / m ² is preferred.

Next, the cationic polymer compound (b) is applied onto the coating film (a) thus formed. In this coating operation, for example, one or more required cationic polymer compounds are dissolved in a suitable solvent, for example, at a concentration of about 0.01 to 5.0% by weight to prepare a coating liquid "hereinafter" coating liquid B ". ) Is prepared, the coating solution B is applied to the coating film surface of the coating solution A, and then dried at a temperature of 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.

Examples of the cationic polymer compound which is the main component of the coating liquid B include polyethyleneimine, polyvinylamine, polyacrylamide, N-vinyl-2-pyrrolidone-acrylamide copolymer, a cyclized polymer of dimethyldiallylammonium chloride, and dimethyl. Cyclic polymer of diethylammonium bromide, cyclized polymer of diallylamine hydrochloride, cyclized copolymer of dimethyldiallyl ammonium chloride and sulfur dioxide, polyvinyl pyridine, polyvinyl pyrrolidone, polyvinyl carbazole, polyvinyl imidazoline, polydimethylaminoethyl acrylate , Polydimethylaminoethyl methacrylate, polydiethylaminoethyl acrylate, polydiethylaminomethacrylate, etc. have a nitrogen atom in the side chain, and the nitrogen atom is positively charged. Cationic polymer electrolyte and the like having the like.

Examples of the solvent for dissolving the cationic polymer compound include the same water and water-miscible solvent as those used in the preparation of the coating liquid A, which may be used alone or in combination of two or more. Used as a mixed solvent.

The coating film of component (b) thus obtained usually has a dry coating amount of preferably 0.001 to 5 g / m ² .

As described above, after the two-step coating process is completed on the inner wall of the polymerization vessel and other portions where the monomers come into contact with each other during the polymerization, a monomer having an ethylenic double bond is added to the polymerization vessel according to a conventional method. A polymer, a polymerization initiator, other required polymerization medium such as water, an additive, for example, a dispersion aid of a monomer may be charged and polymerized.

The present invention also provides, as a second method, a method for preventing the adhesion of polymer scale in the polymerization of a monomer having an ethylenic double bond in a polymerization vessel, which comprises: A coating liquid containing (a) an anionic dye and at least one selected from a metal salt and an inorganic colloid is first applied to the other portion in contact with the monomer, and then the obtained coating film is obtained. The present invention provides a method for preventing adhesion of polymer scale, which comprises performing the above-mentioned polymerization in a polymerization vessel in which (b) the cationic polymer compound is applied.

In this second method, the coating solution (hereinafter referred to as "coating solution A '") used for the coating treatment of (a) contains at least one selected from metal salts and inorganic colloids, and pH adjustment is essential. Anionic dyes used, except
The concentration of the cationic polymer compound, the coating solution, and the coating and drying conditions are the same as those in the first method.

In the second method, the metal salt contained in the coating liquid A'is an alkali metal such as sodium or potassium;
Alkaline earth metals such as magnesium, calcium, barium; zinc group metals such as zinc; aluminum group metals such as aluminum; tin group metals such as titanium and tin; iron group metals such as iron and nickel; chromium such as chromium and molybdenum. Group metals; manganese group metals such as manganese; copper group metals such as copper and silver; silicates, carbonates, phosphates, sulfates, nitrates, borates, acetic acid of metals such as platinum group metals such as platinum Examples thereof include salts, hydroxides, oxides and halides. Also,
As the inorganic colloid, gold colloid, silver colloid, sulfur colloid, ferric hydroxide colloid, stannic acid colloid, silicic acid colloid, manganese dioxide colloid, molybdenum oxide colloid, vanadine pentoxide colloid,
Examples thereof include colloids of aluminum hydroxide, colloids of lithium silicate, and the like, and mechanical colloids, irradiation of ultrasonic waves, electrical dispersion, and colloids of inorganic substances produced by a chemical method. These metal salts and inorganic colloids can be used alone or in combination of two or more.

When the coating liquid A ′ contains a metal salt, the content of the metal salt is usually 0.1 to 500 parts by weight based on 100 parts by weight of the anionic dye.
Weight part, especially 5-150 weight part is preferable. When the inorganic colloid is contained, the content of the inorganic colloid is usually
0.1 to 1000 parts by weight, particularly 5 to 400 parts by weight, are preferred with respect to 100 parts by weight of the anionic dye.

In the second method, the coating liquid A ′ contains a metal salt and / or an inorganic colloid to form a film of an anionic dye, which is insoluble in water and has strong adhesion, on the metal surface such as the inner wall of the polymerization vessel. can do.

Furthermore, in the second method of the present invention, the pH of the coating solution A'is
Is preferably adjusted to 7 or less, and the adhesion of the resulting coating film to the inner wall of the polymerization vessel becomes stronger.

As described above, after the two-step coating process is completed on the inner wall of the polymerization vessel and other portions where the monomers come into contact with each other during the polymerization, a monomer having an ethylenic double bond is added to the polymerization vessel according to a conventional method. A polymer, a polymerization initiator, other required polymerization medium such as water, an additive, for example, a dispersion aid of a monomer may be charged and polymerized.

Examples of the monomer having an ethylenic double bond to which the method of the present invention is applied include vinyl halides such as vinyl chloride, vinyl acetate, vinyl esters such as vinyl propionate, acrylic acid, methacrylic acid and the like. Examples thereof include esters or salts, fumaric acid maleate and esters or anhydrides thereof, gen-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 is effective in any type of polymerization such as suspension polymerization, emulsion polymerization, solution polymerization and bulk polymerization.

Therefore, as the additive substance added to the polymerization system, those which are usually used can be used without any limitation. For example, partially saponified polyvinyl alcohol, methyl cellulose, suspension agents such as polyacrylate, calcium phosphate,
Solid dispersants such as hydroxyapatite, anionic emulsifiers such as sodium lauryl sulfate, sodium dodecylbenzene sulfonate, sodium dioctyl sulfosuccinate, nonionic emulsifiers such as sorbitan monolaurate, polyoxyethylene alkyl ether, calcium carbonate, titanium oxide, etc. Fillers, tribasic lead sulfate, calcium stearate, dibutyltin dilaurate, dioctyltin mercaptide, etc. when stabilized, rice wax, lubricants such as stearic acid, plasticizers such as DOP and DBP, chain transfer such as trichloroethylene and mercaptans Agent, diisopropyl peroxydicarbonate, α, α′-azobis-2,4-dimethylvaleronitrile, lauroyl peroxide, potassium persulfate, cumene hydroperoxide, p-menthane high Even in a polymerization system in which a polymerization catalyst such as dropper oxide is present, the method of the present invention can effectively prevent the adhesion of polymer scale.

Polymerizations in which the process of the invention is particularly preferably carried out include, for example:
It is suspension polymerization or emulsion polymerization of a vinyl halide such as vinyl chloride or vinylidene halide, or a monomer mixture mainly containing them. Also, production of beads, latex of polymers such as polystyrene, polymethylmethacrylate and polyacrylonitrile in a stainless steel polymerization vessel, production of synthetic rubbers such as SBR, NBR, CR, IR and IIR (these synthetic rubbers are usually emulsified). It is also suitable for polymerization in which an 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.

Example 1 Polymerization was carried out as follows using a stainless steel polymerization vessel having an internal volume of 1000 and equipped with a stirrer.

In each experiment, first, an anionic dye was dissolved in a water / methanol mixture (volume ratio: 70/30) at a concentration of 0.5% by weight, and the pH adjusting agent shown in Table 1 was added to adjust the pH to 2.5. The coating liquid [coating liquid A] was prepared. This was applied to the inner wall of the polymerization vessel and other portions where the monomer comes into contact during the polymerization, allowed to stand at 50 ° C for 15 minutes, dried, and washed with water. Next, a coating liquid [coating liquid B] prepared by dissolving a cationic polymer compound in water was applied, dried and washed with water. Table 1 shows the concentration of the anionic dye, the pH adjusting agent, the cationic polymer compound, the coating solution B, and the coating and drying conditions used in each experiment. Experiment Nos. 1 to 4 are comparative examples lacking some or all of the conditions of the present invention.

Next, 400 kg of water, 260 kg of styrene, 140 kg of acrylonitrile, 400 g of partially saponified polyacrylamide and 1.2 kg of α, α'-azobisisobutyronitrile were charged into the polymerization vessel thus treated, and the mixture was stirred at 90%. Polymerization was carried out at ℃ for 5 hours. 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 Polymerization was carried out as follows using a stainless steel polymerization vessel with an internal volume of 1000 and equipped with a stirrer.

In each experiment, first, anionic dye was added to pure water at a concentration of 0.
It is dissolved in 5% by weight, and a metal salt or an inorganic colloid is added to prepare a coating liquid [coating liquid A '], which is coated on the inner wall of the polymerization vessel and other portions where the monomer comes into contact during the polymerization. After drying for 15 minutes, it was washed with water. Next, a coating liquid [coating liquid B] prepared by dissolving a cationic polymer compound in water is applied, and the coating liquid is applied at 50 ° C.
After drying for 15 minutes, it was washed with water. Table 2 shows the concentration of the anionic dye, the cationic polymer compound, the coating liquid B, and the coating and drying conditions used in each experiment. The experiment
Nos. 11 to 16 are comparative examples lacking some or all of the present invention.

Next, in the polymerization vessel thus treated, 40 kg of water, 500 g of sodium oleate, 13 kg of polybutadiene latex (solid content 45), 9.0 kg of styrene, 5.0 kg of acrylonitrile,
40 g of t-dodecyl mercaptan and 140 g of cumene hydroperoxide were charged. After raising the internal temperature to 65 ° C, 200 g of glucose, 2 g of ferrous sulfate and 100 parts of sodium pyrophosphate
g was charged, and polymerization was carried out at 65 ° 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 2.

Example 3 In each experiment, a coating solution [coating solution A ″] obtained by adjusting the coating solution of Experiment No. 21 or 23 of Example 2 to pH 2.5 with phytic acid was polymerized in the same manner as in Example 2. Apply to the inner wall of the polymerization vessel of the reactor and other parts where the monomer contacts during the polymerization, and at 60 ℃
After drying for 15 minutes, it was washed with water. Next, a coating solution [coating solution B] prepared by dissolving a cationic polymer compound in water was applied, dried at 50 ° C. for 15 minutes, and then washed with water.

Then, polymerization was carried out in the same manner as in Example 2 using the polymerization vessel thus coated. After completion of the polymerization, the amount of polymer scale attached to the inner wall surface of the polymerization vessel was measured. The result is the third
Shown in the table.

[Effect of the Invention] According to the method of the present invention, it is possible to effectively prevent adhesion of polymer scale to the inner wall surface of a polymerization vessel or the like in the polymerization of a monomer having an ethylenic double bond, which has been difficult in the past. be able to. 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. Further, by performing the coating once every batch or several batches, the polymerization vessel can be repeatedly used without adhering the polymer scale to the inner wall of the polymerization vessel or the like.

Claims (3)

[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. A polymerizer in which (a) a coating liquid containing an anionic dye and having a pH of 7 or less is applied to the other portion in advance, and then (b) a cationic polymer compound is applied to the obtained coating film. A method for preventing adhesion of a polymer scale, which comprises performing the above-mentioned polymerization. 2. A method for preventing the adhesion of polymer scale in the polymerization of a monomer having an ethylenic double bond in a polymerization vessel, wherein the monomer is in contact with the inner wall surface of the polymerization vessel during the polymerization. A coating solution containing (a) an anionic dye and at least one selected from a metal salt and an inorganic colloid is first applied to the other portions, and then the obtained coating film has (b) a high cationic content. A method for preventing adhesion of polymer scale, which comprises performing the above-mentioned polymerization in a polymerization vessel coated with a molecular compound. 3. The method for preventing adhesion of polymer scale according to claim 2, wherein the coating solution has a pH of 7 or less.