JPH07116245B2 - 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 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 polymer yield, the cooling capacity of the polymerization vessel will decrease, and the polymer scale that adheres to the product will peel off and enter the product. In addition, there are disadvantages such that much labor and time are required for removing the polymer scale.

Conventionally, as a method of preventing the adhesion of the polymer scale to the inner wall surface of the polymerization vessel, for example, a method of applying a polar organic compound, a dye, a pigment or the like to the inner wall surface (Japanese Patent Publication No. 45-30343).
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-55-50887).
No. 54317) is proposed.

These methods are effective in preventing adhesion of polymer scale in the polymerization of a halogenated vinyl monomer such as vinyl chloride or a monomer mixture containing the monomer as a main component.

[Problems to be Solved by the Invention]

However, the monomer used for the polymerization is styrene, α-methylstyrene, acrylic acid ester and acrylonitrile, or other general formula (I): CH ₂ ═CXY (I) [where X is a hydrogen atom or methyl And Y is a hydrogen atom or a formula: —C _n H _{2n + 1} , —COOH, —COONa, —COOC _n H
_{2n + 1, -CN, -C 6} H 5, -C 6 H 4 Z ( where, Z is a hydrogen atom, -
OH, -CH _3, or a group represented by -CH = CH _2), -
OCOC _n H _{2n + 1} , —OC _n H _{2n + 1} or a group represented by —CH═CH ₂ , where n is an integer. ] In the case of a monomer having an ethylenic double bond represented by the following, since these monomers have a large dissolving ability with respect to the coating film having the scale preventing effect formed by the above method. As a result, part or all of the coating film is dissolved and lost, so that the adhesion of the polymer scale could not be effectively prevented. Among them, styrene, α-methylstyrene,
Since the acrylic acid ester and acrylonitrile have remarkably large dissolving ability for the coating film comprising the scale inhibitor, the desired scale preventing effect could not be obtained. Also, particularly when using a stainless steel polymerization vessel,
There has been a problem that polymer scale is likely to adhere.

In view of such conventional problems, an object of the present invention is to polymerize or copolymerize a monomer having a specific ethylenic double bond represented by the general formula (I), to a wall surface of a polymerization vessel or the like. It is an object of the present invention to provide a method capable of effectively preventing adhesion of polymer scale.

[Means for Solving the Problems]

That is, the present invention provides a compound represented by the general formula (I): CH ₂ ═CXY (I) [wherein X is a hydrogen atom or a methyl group, Y is a hydrogen atom or the formula: —C _n H _{2n + 1} , —COOH , −COONa, −COOC _n H
_{2n + 1, -CN, -C 6} H 5, -C 6 H 4 Z ( where, Z is a hydrogen atom, -
OH, -CH _3, or a group represented by -CH = CH _2), -
OCOC _n H _{2n + 1,} a group represented by -OC _n H _{2n + 1} or -CH = CH _2, n is an integer, is usually an integer of 1-4. ] A method of preventing adhesion of a polymer scale in the polymerization of a monomer having an ethylenic double bond represented by: The scale inhibitor contained therein is applied, and then the resulting coating film further contains (b) an alkaline earth metal compound and an anionic dye, and perchloric acid, phytic acid, molybdic acid, hydrochloric acid, tungstic acid and phosphorus. By the addition of at least one acid
In a polymerization vessel in which a coating solution having a pH adjusted to 5 or less is applied to form a coating film, polymerization of the monomer is carried out in an aqueous medium containing a calcium phosphate-based solid dispersant. It is intended to provide a method for preventing adhesion of a coalescing scale.

Examples of the anionic dye contained in the scale inhibitor (a) used in the present invention include CI Acid Yellow 38; CI Acid Red 18,52,73,80,87; CI Acid Violet 11,78; CI Acid Blue. 1,40,59,11
3,116,120,158; CI Acid Orange 3,7; CI Acid Black 1,2,124; CI Direct Orange 2,10,26,97;
CI Direct Red 1,31,92,186; CI Direct Violet 1,22; CI Direct Blue 1,6,71,86,106; C.
I. Direct Black 2,19,32,38,77; CI Direct Green 1,26; Direct Yellow 1; CI Direct Brown 1,37,101; CI Food Yellow 3; CI Reactive Yellow 3; CI Reactive Blue 2,4 , 18; CI Modant Violet 5; CI Modant Black 5; CI Modant Yellow 26; CI Fluorescent Brightening Agent 30,32; CI Solved Butt Black
1; water-soluble anionic dyes such as CI Azoic Brown 2 and the like can be mentioned.

Further, examples of the scale inhibitor containing an anionic dye include the followings.

A group consisting of (a) an alkali metal salt and an ammonium salt of a sulfonic acid type or carboxylic acid type water-soluble anionic dye described in U.S. Pat. No. 4,173,696 (Japanese Patent Publication No. 56-5442,5443 and 5444). Containing at least one compound selected from
A coating solution adjusted below, and (b) in addition to (a) selected from the group consisting of water-soluble cationic dyes having at least one pair of conjugated double bonds and at least one nitrogen atom in one molecule At least one compound selected from the group consisting of (c) silicic acid, silicate compounds, and water-soluble salts of metals other than alkali metals, and having a pH of 7 or less. The adjusted coating liquid, and the number of oxygen atoms in these coating liquids is 3 to
What contains 5 monohydric alcohols, phytic acid, etc.

These can be used alone or in combination of two or more.

The scale inhibitor containing the above anionic dye as a main component,
Components other than anionic dyes may be contained, and examples thereof include those described in US Pat. Nos. 4,173,696 and 4,539,230.

In the method of the present invention, the scale inhibitor (a) is
Usually, the first coating liquid is prepared by dissolving or dispersing in a suitable solvent, and the first coating liquid is applied to the inner wall surface of the polymerization vessel to form a coating film.

Examples of the solvent for dissolving or dispersing the scale inhibitor (a) include water, methanol, ethanol, n.
Alcoholic solvents such as propyl alcohol: aliphatic hydrocarbon solvents such as n-hexane and n-heptane; toluene,
Aromatic hydrocarbon solvents such as benzene, xylene; halogenated hydrocarbon solvents such as methylene chloride, 1-chlorobutane, amyl chloride, dichloroethylene, 1,1,2-trichloroethane; ketone solvents such as acetone and methyl ethyl ketone; formic acid Ester solvents such as methyl, ethyl acetate, methyl acetate, diethylene glycol monomethyl ether acetate; ether solvents such as ethyl ether, 1,4-dioxane, ethylene glycol monomethyl ether; non-pront solvents such as dimethylformamide, dimethyl sulfoxide, acetonitrile And the like, and these are appropriately used alone or as a mixed solvent of two or more kinds.

The pH of the first coating solution is adjusted to a suitable range if necessary. For example, the coating solution prepared by dissolving the water-soluble anionic dye described in US Pat. No. 4,173,696 is adjusted to pH 7 or lower as described above.

The first containing the scale inhibitor (a) thus prepared
The coating solution of 1 may have a solid concentration of about 0.01 to 5% by weight.

The first coating solution is applied to the inner wall surface of the polymerization vessel and preferably to other portions with which the monomer comes into contact during the polymerization, such as a stirring shaft and a stirring blade, and dried to prevent the scale (a). A coating film of the agent is formed. The drying may be performed at room temperature to 100 ° C, for example.

In the coating film thus obtained, the dry coating amount of the scale inhibitor (a) is usually preferably about 0.001 to 5 g / m ² .

Next, a coating solution containing the alkaline earth metal compound and the anionic dye of the above (b) and adjusted to pH 5 or less is applied on the coating film of the scale inhibitor (a) formed as described above. ,dry.

Examples of the alkaline earth metal compound that is a component of the coating liquid (b) used in this second coating step include, for example, silicates, carbonates and phosphates of alkaline earth metals such as magnesium, calcium and barium. , Sulfate, nitrate, borate, acetate, hydroxide, oxide, halide and the like. These may be used alone or in combination of two or more.

Of these, particularly preferred are magnesium carbonate, calcium carbonate, magnesium phosphate, calcium phosphate, barium phosphate, calcium sulfate, calcium borate, magnesium hydroxide, calcium hydroxide, barium hydroxide, magnesium chloride, calcium chloride, etc. Is.

As the anionic dye which is the other component of the coating liquid (b), the anionic dyes exemplified for the scale inhibitor (a) can be used, and one kind alone may be used.
Combinations of more than one species can also be used.

The coating liquid (B) is prepared by dissolving or dispersing one kind or two or more kinds of the alkaline earth metal compound and the anionic dye in a suitable solvent.

The concentration of the alkaline earth metal compound in the coating liquid (B) is not particularly limited as long as the dry coating amount described below can be obtained, but is usually 0.005 to 10% by weight, preferably 0.01 to 5% by weight.

Examples of the solvent used for preparing the coating liquid (b) include water and organic solvents that can be easily mixed with water, such as alcohol-based solvents, ester-based solvents, ketone-based solvents, etc. Used alone or as a mixed solvent of two or more kinds.

Here, the pH of the coating liquid (b) is adjusted to 5 or less so that the alkaline earth metal compound is sufficiently dissolved and a uniform and strong coating film is obtained when the coating liquid (b) is applied. deep.

As the pH adjuster used to adjust the pH of the coating liquid (b), hydrochloric acid, phosphoric acid, perchloric acid, molybdic acid, tungstic acid, phytic acid are used. It is convenient to adjust the pH of the coating liquid (b) when these pH adjusting agents are prepared beforehand as an aqueous solution having an appropriate concentration. Next, the coating solution (b) may be applied to the coating surface of the scale inhibitor (a) and then dried at a temperature of, for example, 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 coating is room temperature to 100 ° C.
It is good to set it to about.

The total dry coating amount of the alkaline earth metal compound and the anionic dye in this coating liquid (b) is usually preferably 0.001 to 5 g / m ² .

In this manner, after the inner wall of the polymerization vessel, and preferably other portions where the monomers come into contact with each other during the polymerization, are subjected to a two-step coating treatment to form a coating film, the polymerization vessel is subjected to a conventional method according to a conventional method. A monomer having an ethylenic double bond represented by the general formula (I), a polymerization initiator, other necessary polymerization medium and additives, for example, a monomer dispersion aid are charged and polymerized. Just do it.

Examples of the monomer having an ethylenic double bond of the general formula (I) to which the method of the present invention is applied include vinyl acetate,
Examples thereof include vinyl esters such as vinyl propionate; acrylic acid, methacrylic acid and their esters or salts; diene monomers such as butadiene, chloroprene and isoprene; styrene, acrylonitrile, α-methylstyrene, vinyl ether and the like.

The method of the present invention is particularly applicable to a polymerization method in which the above-mentioned monomers are polymerized in an aqueous medium containing a calcium phosphate-based solid dispersant. That is, the above-mentioned coating film exerts a remarkable scale preventing result against the polymerization in the dispersion system.

Typical examples of the calcium phosphate-based solid dispersant include calcium phosphate and hydroxyapatite.
The polymerization method is not particularly limited as long as it is carried out in an aqueous medium, and may be, for example, suspension polymerization or emulsion polymerization.

Therefore, the additive substance to be added to the polymerization system is also used without particular limitation, whether it is used for suspension polymerization or emulsion polymerization, provided that a calcium phosphate-based solid dispersant is used. You can That is, for example, suspending agents such as partially saponified polyvinyl alcohol, methyl cellulose, polyacrylate; anionic acid emulsifiers such as sodium lauryl sulfate, sodium dodecylbenzenesulfonate, sodium dioctylsulfosuccinate; sorbitan monolaurate, polyoxyethylene alkyl ether, etc. Nonionic emulsifiers; fillers such as calcium carbonate and titanium oxide; stabilizers such as tribasic lead sulfate, calcium stearate, dibutyltin dilaurate, dioctyltin mercaptide; rice wax,
Lubricants such as stearic acid; 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 azobis-2,4-dimethylvaleronitrile, lauroyl peroxide, potassium persulfate, cumene hydroperoxide, p-menthane hydroperoxide, etc. is present, the method of the present invention is a polymer scale. Can be effectively prevented.

Polymerizations in which the process of the invention is particularly preferably carried out include, for example:
The copolymerization of acrylonitrile and acetylene and the homopolymerization of styrene by the suspension polymerization method using a solid dispersant.
In addition, the production of beads, latex of polymers such as polystyrene, polymethylmethacrylate, polyacrylonitrile, etc. in a stainless steel polymerization vessel; production by emulsion polymerization of synthetic rubber such as SBR, NBR, CR, IR, IIR; production of ABS resin. It is also suitable for the polymerization to be carried out.

In carrying out the method of the present invention, the coating operation of the coating solution may be appropriately performed once in every batch or several batches, whereby the polymer scale is not attached to the inner wall of the polymerization vessel or the like, The polymerizer can be used repeatedly.

〔Example〕

Hereinafter, the present invention will be described in detail with reference to Examples and Comparative Examples. In addition, in each of the tables below, the experiment numbers marked with *
Are comparative examples, and other experiment Nos. Are examples of the present invention.

Preparation of Prepolymer The prepolymer used in Example 1 was prepared by the following method.

In the polymerization vessel, styrene 6000g, polybutadiene rubber 720g,
Mineral oil (CP-50, manufactured by Idemitsu Kosan Co., Ltd.) 480 g and n-dodecyl mercaptan 6000 g were charged, and the mixture was heated at 115 ° C. for 5 days.
A prepolymer was prepared by reacting for a time.

Example 1 In each experiment No., polymerization was carried out as follows using a stainless steel polymerization vessel with an internal volume of 20 and equipped with a stirrer.

In Experiment Nos. 2 and 4 to 12, the first scale inhibitor was used.
The anionic dyes shown in the table were dissolved or dispersed in water to a concentration of 0.5% by weight and adjusted to pH 3 with hydrochloric acid.
Then, apply the solution of the scale inhibitor shown in Table 1 to the coating solution (a).
This was applied to the inner wall of the polymerization vessel and other portions where the monomer comes into contact during the polymerization, and was heated at 50 ° C. for 15 minutes and dried to form a coating film.

Next, the alkaline earth metal compound and the anionic dye were dissolved or dispersed in water at a total concentration of 0.5% by weight, and the pH was adjusted with a pH adjuster to prepare a coating solution (B). This coating liquid (b) was applied on the coating film formed as described above, dried and washed with water to form a coating film.

However, Experiment Nos. 1 to 3 are comparative examples in which the coating liquid was not applied or only one of the coating liquids (a) and (b) was applied. Experiment Nos. 9, 10, 13 and 15 are coating liquids (a)
Or (b) is a comparative example which does not satisfy the conditions of the present invention. The scale inhibitor of the coating liquid (a) used in each experiment, the alkaline earth metal compound of the coating liquid (b), the anionic dye, the pH adjuster and the pH of the coating liquid (b), and the pH of the coating liquid (b) Table 1 shows the weight ratio of alkaline earth metal compound / anionic dye, coating temperature and drying time.

Next, in the polymerization vessel thus formed a coating film, water 7000g,
7,000 g of the prepolymer obtained in the above Preparation Example, 70 g of hydroxyapatite, 0.14 g of sodium dodecylbenzenesulfonate, 17.5 g of benzoyl peroxide and t- of perbenzoic acid
Butyl 10.5 g was charged. Next, after reacting at 92 ° C. for 3.5 hours, it was reacted at 135 ° C. for 1 hour to produce a polymer. After the polymerization was completed, the amount of polymerization 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 was formed by coating the coating solution (a) and the coating solution (b) in the same manner as in Example 1 on a stainless steel polymerization vessel having an inner volume of 300 and equipped with a stirrer. However, in Experiment Nos. 16 to 18, the coating liquid was not applied, or the coating liquid (a) or (b)
This is a comparative example in which only one of the above is applied. Experiment No.2
3, 24, 28 and 29 are comparative examples in which the coating liquid (a) or (b) does not satisfy the conditions of the present invention. The scale inhibitor of the coating liquid (a) used in each experiment, the alkaline earth metal compound of the coating liquid (b), the anionic dye and the pH adjusting agent, and the alkaline earth metal / anionic dye in the coating liquid (b) The weight ratio is shown in Table 2.

Next, styrene 60k
g, acrylonitrile 40 kg, water 100 kg, hydroxyapatite 2 kg, sodium lauryl sulfate 40 g, t-dodecyl mercaptan 300 g and lauroyl peroxide 400 g were charged, and the mixture was stirred at an internal temperature of 70 ° C for 1 hour and then at 70 ° C for 2 hours.
To 80 ° C. Then, a polymer was produced by reacting at 80 ° C. for 1 hour. 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.

Comparative Experimental Example Polymerization was performed in exactly the same manner as in Experiment No. 4 except that sodium phosphate was used instead of calcium phosphate in the coating solution (b) used in Experiment No. 4 of Example 1. . As a result, a scale adhesion of 330 g / m ² was observed.

[Results of Invention]

According to the method of the present invention, it is difficult to effectively prevent scale from adhering to the coating film of the conventional scale agent because of its high dissolving ability. In the polymerization and copolymerization of the monomer having a heavy bond, the adhesion of the polymer scale to the inner wall surface of the polymerization vessel can be effectively prevented. In particular, even in a polymerization system containing styrene, α-methylstyrene, acrylic ester, acrylonitrile or the like, which has a remarkably high solubility, adhesion of polymer scale can be effectively prevented.

Front Page Continuation (72) Inventor Susumu Ueno No. 1 Towada, Kamisu-cho, Kashima-gun, Ibaraki Shin-Etsu Chemical Co., Ltd., Polymer Functional Materials Research Center (56) References Japanese Patent Publication Sho 53-6025 (JP, B2) ) Japanese Patent Sho 53-6024 (JP, B2) Japanese Patent Sho 63-15281 (JP, B2) Japanese Patent Sho 62-20201 (JP, B2)

Claims (1)

[Claims] 1. A general formula: CH ₂ ═CXY [where X is a hydrogen atom or a methyl group, Y is a hydrogen atom or a formula: —C _n H _{2n + 1} , —COOH, —COONa, —COOC _n H
_{2n + 1, -CN, -C 6} H 5, -C 6 H 4 Z ( where, Z is a hydrogen atom, -
OH, -CH _3, or a group represented by -CH = CH _2), -
OCOC _n H _{2n + 1} , —OC _n H _{2n + 1} or a group represented by —CH═CH ₂ , where n is an integer. ] A method for preventing adhesion of a polymer scale in the polymerization of a monomer having an ethylenic double bond represented by: A scale preventive agent containing is applied, and then the resulting coating film further contains (b) an alkaline earth metal compound and an anionic dye, and perchloric acid, phytic acid, molybdic acid, hydrochloric acid, tungstic acid and With the addition of at least one of phosphoric acid
In a polymerization vessel in which a coating solution having a pH adjusted to 5 or less is applied to form a coating film, polymerization of the monomer is carried out in an aqueous medium containing a calcium phosphate-based solid dispersant. How to prevent coalescence of scale.