JPH0570505A - Method for polymerizing vinyl chloride monomer - Google Patents

Abstract

PURPOSE:To prevent polymer scale deposition on the inner wall and other parts of a polymerization vessel. CONSTITUTION:The title method comprises forming a film of a mixture of an electron donor dye and an arylsulfonic acid and/or of a reaction product of both on the inner wall of a polymerization vessel and/or on the surface of a device attached to the vessel, and then polymerizing vinyl chloride monomer or a copolymerizable monomer mixture containing vinyl chloride monomer as the main ingredient in an aqueous medium while spindling water on those surfaces of the vessel and the attached device which are in contact with the gas phase.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for polymerizing vinyl chloride-based monomers, which prevents polymer scale from adhering to the inner wall surface of a polymerization vessel and / or the surface of equipment attached to the polymerization vessel.

[0002]

BACKGROUND OF THE INVENTION Vinyl chloride polymers are usually produced by emulsion polymerization or suspension polymerization of vinyl chloride monomers in the presence of a polymerization initiator in an aqueous medium containing an emulsifier or dispersant. In this polymerization process, the inner wall of the polymerization vessel, the stirring blade that is an accessory device of the polymerization vessel, the baffle, the wall surface of the reflux condenser and the wall surface of the various pipes installed in the polymerization vessel such as vinyl chloride-based monomer (hereinafter, These are collectively referred to as "inner wall of the polymerization vessel, etc.)", and the polymer scale adheres to this, which lowers the polymer yield, reduces the cooling capacity of the polymerization vessel, and causes the exfoliation scale to be mixed into the product. Therefore, the molded product obtained from this has a drawback that, for example, fish eyes are generated, and the physical properties of the molded product are deteriorated.Moreover, excessive labor and time are required to remove the scale adhering to the inner wall of the polymerization vessel. However, there is a problem that the operating rate of the polymerization vessel is reduced.

Furthermore, if it is attempted to remove the adhered scale by entering the polymerization vessel, it will be exposed to vinyl chloride monomer, which is not preferable in terms of occupational health. Therefore, to solve these problems, for a person who manufactures a vinyl chloride-based polymer,
It has been a longstanding concern. Conventionally, as a method of preventing the polymer scale from adhering to the inner wall of the polymerization vessel, a method of applying a substance having a scale suppressing effect to the inner wall of the polymerization vessel has been proposed.

For example, (1) a method of applying a polar compound such as an amine compound, a quinone compound, an aldehyde compound, a dye and a free radical inhibitor, (2) a method of applying an alkali metal salt of xanthogenic acid, (3) isobutylene. -A method using a maleic anhydride copolymer as a fixing agent,

(4) An alkali metal salt of xanthogenic acid,
A method of applying three components of polyethyleneimine and aldehyde, (5) a method of applying a mixture of an electron-donating basic dye and an electron-accepting dye, and (6) a water-soluble anionic dye and a water-soluble cationic dye. Examples include a method in which a phytic acid compound is added to an aqueous solution and a solution prepared to have a pH of 7 or less is applied.

However, in the above methods (1) to (5), it is difficult to say that one or both of the effect of preventing scale adhesion and the effect of sustainability is excellent, that is, both effects are excellent and satisfactory. It was not a profitable method.
In addition, although the effect of scale adhesion prevention and its sustainability are almost satisfied by the method (6), the above-mentioned effects are not obtained in practice unless the pH after application is set to a strong acid of 3 or less. I can't get it. In this case, since the inner wall of the polymerization vessel is treated with an acid, it is preferable from the viewpoint of the effect of preventing scale adhesion and durability, but it is disadvantageous in terms of corrosion of the inner wall of the polymerization vessel.

For example, in a material such as stainless steel SUS304, corrosion or stress corrosion cracking occurs, which causes a problem in safety, and the cost of stainless steel SUS316 is high.
It was necessary to use materials such as There are various methods for applying the scale anti-adhesive agent, such as brush coating, spray application with a one-fluid nozzle or a two-fluid nozzle, and a method in which the scale anti-adhesive agent is once filled in the polymerization vessel and then withdrawn. , But not limited to.

The last method is a less preferable method because there is a time constraint from the time when the scale anti-adhesion agent is filled to the time when it is collected, and it is necessary to prepare a large amount of the scale anti-adhesion agent, which is economically limited. is not. According to other methods, it is difficult to apply all over the ceiling of the polymerization vessel or a structurally complicated portion connected to the upper portion of the polymerization vessel, such as various pipes and a reflux condenser. Further, even if it is applied uniformly, these gas phase portions have a scale generation due to the adhesion of the scattered polymer, so that there is a drawback that the measures against the application of the scale adhesion preventing agent are not sufficient.

[0009]

DISCLOSURE OF INVENTION Problems to be Solved by the Invention As a result of intensive studies made by the present inventors to solve the problems of the prior art,
A film of a mixture and / or a reaction product containing at least one kind of electron-donating dye and at least one kind of arylsulfonic acid is formed, and then water is sprinkled or allowed to flow down on the inner surface of the gas phase part of the polymerization vessel and the auxiliary equipment. While carrying out the polymerization, it was found that the effect of preventing scale adhesion and the effect of its durability are further improved, and the present invention has been completed. That is, the object of the present invention is excellent in the effect of preventing scale adhesion such as the inner wall of the polymerization vessel and this effect can be maintained for a long period of time, and furthermore, the polymerization method of a vinyl chloride monomer that does not cause corrosion in the polymerization vessel or the like. To provide.

[0010]

However, the gist of the present invention is that a vinyl chloride monomer or a mixture of copolymerizable monomers mainly containing vinyl chloride monomer is used in an aqueous medium. Before the polymerization, a mixture of the electron-donating dye (a) and the arylsulfonic acid (b) and / or on the inner wall of the polymerization vessel and / or the surface of the equipment attached to the polymerization vessel
Alternatively, a method of polymerizing a vinyl chloride-based monomer is characterized in that a film of a reaction product is formed, and then polymerization is carried out while pouring water on the inner surface of the gas phase portion of the polymerization vessel and equipment attached to the polymerization vessel. This film is formed by polymerizing a solvent solution or dispersion of a reaction product obtained by previously heating or irradiating a mixed solution or dispersion of an electron-donating dye (a) and an arylsulfonic acid (b). It is suitable to apply it to the inner wall of the container.

The present invention will be described in more detail. The electron-donating dye (a) used in the present invention (hereinafter referred to as component (a)) is a xanthene dye such as rhodamine B, an azine dye such as CI Basic Red 2,
CI Basic Red 12, CI Basic Yellow 1
Methine and polymethine dyes such as 1, triarylmethane dyes such as CI Basic Blue 1, thiazine dyes such as CI Basic Blue 9, azo dyes such as CI Basic Orange 2, CI Basic Orange 1
Acridine dye like 4, CI Basic Yellow 2
And basic dyes such as thiazole dyes and onium dyes.

In addition to basic dyes, among disperse dyes, direct dyes, azoic dyes, fluorescent dyes, solvent dyes or dye intermediates, pigments, etc., molecules having a Lewis base character, nitrogen, oxygen, and sulfur Examples are molecules having a shared electron pair. At least one of these dyes is used. On the other hand, as the aryl sulfonic acids (II) (hereinafter referred to as the component (II)), benzenesulfonic acid, o-, m-, p-toluenesulfonic acid, ethylbenzenesulfonic acid, dodecylbenzenesulfonic acid, 2,4
-Mono- or 2-, such as dimelbenzene sulfonic acid
The polynuclear aromatic sulfonic acids such as the above substituted alkylbenzene sulfonic acids and β-naphthalene sulfonic acids can be mentioned.

The component (b) may be a compound containing, in addition to the sulfonic acid group, a substituent such as a carboxylic acid, a quinone or a nitro group, which imparts a characteristic as an electron accepting property.
At least one of these components (b) is used. Further, the component (b) may be a compound having a high electron-accepting ability even if it partially contains an electron-donating substituent, and having a sufficient ability to accept an electron to an electron-donating dye. It can be used without problems.

The proportions of component (a) and component (b) used are
Although not particularly limited, considering the charge effect or reaction effect of both, the effect of preventing scale adhesion, and the persistence thereof, the weight ratio of the former to the latter is 1:10 to 10: 1, preferably 1: 5. Is in the range of up to 5: 1. Also, the component (a)
And component (b) form an aggregate, associate, complex or reaction product of the active group in the molecule of component (b) and the sulfonic acid group of component (b), but the activity of component (b) It is desirable to control the use ratio of the component (b) by the number of groups, for example, to prevent the loss of the expensive dye (a) and measure its effective use, and also to collect sulfonic acid compounds, aggregates, complexes or reaction products. Considering that the component (b) is easily removed from the component (b), it is recommended to use the component (b) in excess molar ratio and excess equivalent amount. The molar ratio of component (a) and component (b) is 1: 1 to 1: 1.
00, preferably 1: 1 to 1:50, more preferably 1: 1 to 1:10.

In the method of the present invention, the component (a) is applied to the inner wall of the polymerization vessel or the like.
And forming a mixture of the component (b) and / or a film of a reaction product. The coating film can be formed by sequentially applying a solvent solution or dispersion liquid of each of the component (a) and the component (b) to the inner wall of the polymerization vessel or the like, or by forming a mixed liquid in advance and then applying the mixed liquid.

Examples of the solvent include water, alcohol solvents, ester solvents, ketone solvents, hydrocarbon solvents, chlorinated hydrocarbon solvents or aprotic solvents such as dimethylformamide, dimethylsulfoxide, acrylonitrile and the like. Examples include a mixed solvent of two or more kinds. Further, a heat treatment or a light irradiation treatment may be performed after the coating to accelerate the formation of the reaction product film.

In the method of the present invention, a particularly preferable method is to apply a solvent solution or dispersion in which a reaction product of the component (a) and the component (b) has been formed in advance to the inner wall of the polymerization vessel and the like to form a coating film. It is a method of forming. In order to previously generate a reaction product from the component (a) and the component (b), the reaction product is dissolved or dispersed in the above solvent and then subjected to heat treatment or light irradiation treatment. The above-mentioned solvent is not limited to one kind, and a mixed solvent of two or more kinds may be used. Moreover, even if both components are simultaneously dissolved or dispersed in a solvent, the solution or dispersion of the component (a) and the component (b) can be prepared by dissolving or dispersing each component in each solvent and then preparing the solution or dispersion. The liquids may be mixed.

To produce a reaction product in this mixed solution or dispersion (hereinafter referred to as "solvent solution"),
The solvent solution is heat treated. The heat treatment may be carried out by refluxing under normal pressure, or by using a pressure vessel and heating to a temperature not lower than the boiling point of the solvent. It is not limited to this, and the heating temperature and the heating time may be appropriately determined depending on the reactivity of each component. Usually, the heating temperature is 200 ° C or lower, preferably 50 to 170 ° C, particularly 60 to 150 ° C.

Furthermore, the reaction product can also be produced by irradiating the solvent solution with light from the visible region to the ultraviolet region. In this case, it is necessary that the components in the solvent solution be excited. In the reaction in the solvent solution, the lesser one of the component (a) and the component (b), that is, the component having a lower concentration has a reaction conversion rate of 50% or more, preferably 70% or less.
% Or more, and particularly preferably 80% or more. This solvent solution can be used as it is as a coating liquid for the inner wall of the polymerization vessel or the like.

The solvent solution containing the reaction product is preferably used after removing the unreacted arylsulfonic acid (b) in the solvent solution in order to avoid corrosion of the inner wall of the polymerization vessel and the like. Generally, a recrystallization method, a uniform precipitation method, a precipitation exchange method, which utilizes a difference in solubility between a reaction product and a component (b) in a solvent solution,
Reprecipitation method, precipitation method such as fractional precipitation method, solvent extraction method, ion exchange membrane dialysis method, molecular sieve, molecular sieve chromatography, adsorption partition chromatography, ion exchange chromatography, electrophoresis method, foaming separation method, density The reaction product is separated by a gradient centrifugation fractionation method or the like, and the reaction product is redissolved or redispersed before use.

Alternatively, after the solvent solution is vaporized to precipitate a solid, fractional sublimation or sublimation with a carrier gas may be performed to separate the reaction product from the component (b). The reaction product thus separated is redissolved or redispersed, or the concentration thereof is adjusted to obtain a solvent solution containing an appropriate amount of the reaction product, which is used as a coating solution for the inner wall of the polymerization vessel or the like.

As a coating method, a brush coating method, a spray method using a one-fluid or a two-fluid nozzle, a method of once filling the inner wall of the polymerization vessel with a solvent solution, and then recovering the solvent solution, etc. are particularly preferable as long as the coating can be performed uniformly and on the entire surface. The method is not limited. Two
In the method of spraying using a fluid nozzle, a non-condensable gas such as air or nitrogen gas, a condensable gas such as steam, or the like is used as the gas medium, but in the method of the present invention, the component (a) and In order to accelerate the reaction of the component (b), it is preferable to employ a method in which steam is used as a gas medium and the solvent solution is heated at the same time as spraying.

After applying the solvent solution, the inner wall of the polymerization vessel is usually heated by passing warm water or steam through the jacket of the polymerization vessel to accelerate the reaction of the components (a) and (b) and vaporize and remove the solvent. At the same time, the mixture and / or the reaction product is dried and fixed to the inner wall of the polymerization vessel or the like to form a film. The inner wall of the polymerization vessel is heated at a temperature below 150 ° C.
The temperature is preferably 50 to 120 ° C. for 1 to 100 minutes, and more preferably 70 to 100 ° C. for 2 to 30 minutes.

After the above-mentioned coating step, the excess component (a) or component (b) or reaction product is removed by a method such as washing with water to complete the coating step. Mixture on inner wall of polymerization vessel and / or
Or the coating by reaction product coating is usually 0.001 g /
It is preferably formed in a range of m ² or more, preferably 0.01 to 5 g / m ² . If the coating amount is less than 0.001 g / m ² , the scale adhesion prevention effect is not sufficient and the amount is 5 g / m ²
If the amount is larger than the above range, the effect of preventing scale adhesion is satisfactory, but on the contrary, the polymerization reaction and the product are adversely affected, such as delay of polymerization reaction, peeling of reaction product, and coloration.

In the method of the present invention, the component (a) is applied to the inner wall of the polymerization vessel or the like.
And an aqueous medium of a mixture of components (b) and / or a vinyl chloride monomer or a mixture of copolymerizable monomers mainly composed of a vinyl chloride monomer using a polymerization vessel formed with a film of a reaction product Among them, the polymerization is carried out while spraying water on the inner surface of the gas phase portion such as the inner wall of the polymerization vessel or while flowing water, that is, while pouring water on the inner surface of the gas phase portion.

The water injection method is not particularly limited, but for example, from a single or a plurality of water injection ports leading to the inner surface of the nozzle or the reflux condenser, to the nozzle, the inner surface of the condenser and the inner surface of the gas phase portion of the polymerizer itself. How to make the water flow down, the nozzle,
A method of arranging a single or a plurality of water injection nozzles in a gas phase portion of a reflux condenser, a polymerization vessel or the like in which a monomer comes into contact, and spraying or flowing water from the nozzle toward the inner surface of the gas phase portion is a method. Adopted.

The amount of water injected is not of course an obstacle to the polymerization reaction, but it is desirable to determine it in consideration of the size of the polymerization vessel and the initial charging amount. For example, a nozzle or a reflux condenser. In the case of, the proportion should be set in proportion to the tube diameter, and in the case of the vapor phase part of the polymerization vessel, it should be determined in proportion to the inner diameter of the polymerization vessel. Specifically, in the former case, 0.1 l / cm ( cm indicates the tube diameter), preferably 1 l / cm or more, and in the latter case, 0.
It is selected from the range of 5 l / m (m represents the inner diameter of the polymerization vessel) or more, preferably 5 l / m or more, and particularly 50 l / m or more.

For the polymerization of the vinyl monomer in the method of the present invention, all of the commonly known polymerization recipes are adopted, and the dispersant, emulsifier, polymerization initiator, etc. used need not be special. A commonly used dispersant, emulsifier, or polymerization initiator can be used. For example, as a dispersant and an emulsifier, a partially saponified product of polyvinyl acetate, an acrylic acid copolymer, a maleic anhydride copolymer, a cellulose derivative,
Protective colloidal agents such as gelatin, powdered densities,
Alternatively, natural polymer compounds, esters of higher fatty acids and polyhydric alcohols, nonionic surfactants such as polyoxyethylene derivatives, metal salts of higher fatty acids, anionic surfactants such as alkali salts of higher alcohol sulfates are used. Be done.

As the polymerization initiator, benzoyl peroxide, lauroyl peroxide, dioctyl peroxycarbonate, organic peroxides such as acetylcyclohexylsulfonyl peroxide, azo compounds such as azobisisobutyronitrile and dimethylvaleronitrile, potassium persulfate, Persulfates such as ammonium persulfate are used.

The vinyl chloride-based monomer used in the method of the present invention is not only vinyl chloride monomer itself, but also vinyl chloride monomer mainly composed of vinyl chloride monomer and copolymerizable therewith. It may be a mixture of monomers. Examples of the copolymerizable monomer include olefins such as ethylene and propylene, vinyl esters such as vinyl acetate and vinyl stearate, vinyl ethers such as ethyl vinyl ether and cetyl vinyl ether, acrylic acid esters, maleic acid and fumaric acid. Copolymerizable with conventionally known vinyl chloride such as unsaturated carboxylic acid derivatives such as esters and anhydrides, maleimide and its N-substituted compounds, aromatic vinyl compounds such as styrene, unsaturated nitrile compounds such as acrylonitrile. Any of these monomers can be used.

[0031]

According to the method of the present invention, in the polymerization reaction,
Since there is no or negligible amount of scale attached to the inner wall of the polymerization vessel, especially on the inner surface of the gas phase of the polymerization vessel and the equipment attached to the polymerization vessel, the production of fish eyes etc. in the final processed product is greatly reduced. The quality of the polymer is further improved, and the number of cleanings of the inner wall of the polymerization reactor is significantly reduced, so it is possible to continue operation without cleaning for a long period of time, productivity is improved, and extremely advantageous results from the viewpoint of cost. can get.

Further, not only the management of operations such as cooling becomes easy, but also a reflux condenser can be used as a new cooling means. Furthermore, when a low boiling point polymerization initiator such as t-butylperoxypivalate or diisopropylperoxydicarbonate which is conventionally known to be particularly remarkable in the formation of scale deposits is used in the method of the present invention,
Alternatively, even when a special auxiliary agent such as sorbitan ester is added for quality improvement, a stable scale adhesion preventing effect is exhibited.

When a solvent solution from which arylsulfonic acids are separated and removed is used as a coating solution for forming a film, it does not corrode even if a material such as SUS304 is used because it is not strongly acidic and the polymerization vessel and its auxiliary Regarding equipment, SUS3
Since it is possible to use an inexpensive material such as 04, the cost can be reduced in terms of equipment.

[0034]

EXAMPLES Next, the method of the present invention will be specifically described by way of examples, but the present invention is not limited to the following examples unless it exceeds the gist.

Examples 1 to 5, Comparative Examples 1 to 7 Electron-donating dye, CI solvent black 3 as component (a), p-toluenesulfonic acid and 2,4-dimethylbenzenesulfonic acid as component (b) Was added to methanol in the proportions shown in Table 1 to produce reaction products under the treatment conditions shown in Table 1. The reaction conversion rate of the component (a) is shown in Table 1, and this solvent solution was directly used as a coating solution for the inner wall of the polymerization vessel and the like. This coating liquid was sprayed onto the inner wall of a stainless steel polymerization vessel having an internal volume of 50 m ³ , baffles, stirring blades and the inner surfaces of various nozzles using a one-fluid spray nozzle,
After forming a film, it was washed once with water. Coating amount is 2.37
The coating was almost uniform at g / m ² .

Next, using this polymerization vessel, deionized water 20
Charge m ³ , vinyl chloride monomer 18 m ³ , polyvinyl acetate partially saponified 13 kg and lauroyl peroxide 6 kg, and raise the temperature to 55 ° C., and at the same time, inject water into the various nozzles and the vapor phase of the polymerization vessel at the flow rates shown in Table 1. Meanwhile, the polymerization was carried out until the predetermined polymerization rate was reached. This polymerization was set as one batch, the above coating was performed for each batch, the polymerization was repeated up to 90 batches, the slurry was taken out, the inside of the vessel was washed with water and dried, and the scale adhesion amount at each place was measured.

[0037]

[Table 1]

The reaction conversion rate in Table 1 was determined as follows. Method for measuring reaction conversion rate The decrease rate of the absorption spectrum of the component (a) in the wavelength range of 450 to 600 nm was measured by a spectrophotometer and defined as the reaction conversion rate. Reaction conversion rate = {(A ₀ −A) / A ₀ } × 100 A ₀ : Absorbance of component (a) A: Absorbance after treatment

The reaction conversion rates in Examples 1 to 5 are the maximum absorbances when the component (a) becomes a complex because the component (a) easily becomes a complex due to the excessive addition of the component (b). a reduced absorbance at that wavelength 540nm and a ₀ was calculated based on the equation as a. As is clear from Table 1, by coating the mixture of the component (a) and the component (b) or the reaction product and then polymerizing while pouring water, an excellent effect of preventing scale adhesion can be obtained.

Examples 6 to 9 CI Solvent Black 3 was mixed with p-toluenesulfonic acid,
2,4-Dimethylbenzenesulfonic acid and β-naphthalenesulfonic acid were dissolved in methanol at the concentrations shown in Table 2, refluxed for 300 minutes, and then cooled to room temperature. Four times the volume of water was added to these to precipitate the reaction products, which were collected by filtration (hereinafter referred to as filtration reaction products). The filtered reaction product was dissolved in ethanol to a concentration of 0.7% by weight, 4 times volume of water was added again, and the precipitation filtration operation was repeated to obtain a purified reaction product.

The filtration reaction product and the purified reaction product were mixed with each other.
A 7 wt% ethanol solution was used as a coating liquid, and the coating amount was 1.
It was sprayed at 11 g / m ² to form a film and washed once with water. Using this polymerization vessel, polymerization and coating were repeated 450 batches in the same manner as in Example 1 (same charge amount, same condition). Table 2 also shows the pH of the coating solution, the amount of scale attached, and the corrosiveness.

[0042]

[Table 2] In addition, pH of the solvent solution of Examples 1-5 and Comparative Examples 3-5
Was 1.9, the corrosion rate was 0.3 mm / year, and the corrosion rates of Comparative Examples 1, 2, 6, and 7 were 0.05 mm / year. From the results shown in Table 2, those obtained by applying an excess amount of the component (b) to the solvent solution applied to the inner wall of the polymerization vessel or the like have good scale adhesion prevention properties and substantially no corrosion of the inner wall of the polymerization vessel. I understand.

Claims (4)

[Claims] 1. When polymerizing a vinyl chloride monomer or a mixture of copolymerizable monomers mainly comprising vinyl chloride monomer in an aqueous medium, the inner wall of the polymerization vessel and / or
Or the electron donating dye (a) on the surface of the equipment attached to the polymerization vessel
A vinyl chloride characterized in that a film of a mixture of phenylene and aryl sulfonic acid (II) and / or a reaction product is formed, and then polymerization is carried out while pouring water on the inner surface of the gas phase part of the polymerization vessel and equipment attached to the polymerization vessel. Method of polymerization of base monomer. 2. The method for polymerizing a vinyl chloride-based monomer according to claim 1, wherein a film is formed by applying a mixed solution or dispersion of the electron-donating dye (a) and the arylsulfonic acid (b). 3. A mixed solution or dispersion of an electron-donating dye (a) and an arylsulfonic acid (b) is previously heat-treated or light-irradiated so that the reaction conversion rate of the lesser component is 50% or more. The method for polymerizing a vinyl chloride-based monomer according to claim 1 or 2, wherein a mixed solution or dispersion containing a reaction product and unreacted components is formed and then applied to form a film. 4. An electron-donating dye (ii) and an arylsulfonic acid (ii) in excess equivalent to the dye (ii).
In advance, the mixed solution or dispersion of (1) is subjected to heat treatment or light irradiation to generate a reaction product, and then unreacted aryl sulfonic acid (B) is removed to apply a solution or dispersion to obtain a reaction product. The method for polymerizing a vinyl chloride-based monomer according to claim 1 or 3, which forms a film of the product.