JP2000264905A - Polymerization of vinyl chloride - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide both a method and an apparatus for efficiently feeding a polymerization inhibitor so as to deal with the occurrence of an abnormal reaction in a suspension polymerization of vinyl chloride. SOLUTION: In this method for a suspension polymerization of vinyl chloride using a jacketed bottom stirring type reaction vessel 2 equipped with a back flow condenser 1, a mechanical seal flushing water line 9 at the bottom of the reaction vessel is equipped with a line 8 for feeding a polymerization inhibitor together with a booster pump 9.

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, and more particularly to a method for safely and promptly suppressing or stopping a polymerization reaction against an abnormal reaction which occurs suddenly during polymerization of vinyl chloride.

[0002]

2. Description of the Related Art In the polymerization of vinyl chloride, an abnormal reaction may occur due to a change in a catalyst addition amount, a change in polymerization temperature adjustment, and the like. In general, an abnormal reaction is a phenomenon in which a predetermined polymerization temperature cannot be maintained due to insufficient heat removal, and in the worst case, the reaction runs away and the internal temperature of the reaction tank rapidly increases, and the internal pressure increases accordingly. It is dangerous.

Conventionally, when such an abnormal reaction occurs,
For example, a polymerization inhibitor was introduced from a pot installed at the top of the reaction tank to cope with the problem.

[0004]

However, when an abnormal reaction occurs, the reaction proceeds rapidly, so that the upper part of the reaction suspension may be clumped with a vinyl chloride resin, and is generally used. It takes a long time to inactivate the active reaction suspension present at the bottom of the reaction tank only by adding the polymerization inhibitor from the pot at the top of the reaction tank as described above. Can hardly be expected. It is also conceivable to add a polymerization inhibitor directly into the reaction suspension from the bottom of the reaction tank.
If a dedicated line for polymerization inhibitor is installed at the bottom of the reaction tank, it is a line that is not used during normal times, so when it is necessary to actually add it, there is a possibility that the polymerization inhibitor may not be added due to clogging due to precipitation. is there.

[0005]

Means for Solving the Problems The inventors of the present invention have made intensive studies in order to solve the above-mentioned problems, and as a countermeasure against these problems, as a countermeasure, the vinyl chloride resin powder has clogged the clearance between the stirring shaft and the mechanical seal casing. The use of an existing mechanical seal flushing water line, which is always used to prevent polymerization, allows the polymerization reaction to be stopped safely, quickly and reliably without clogging due to sedimentation in an emergency. It is. That is, the present invention provides a suspension polymerization method for vinyl chloride using a jacketed bottom-stirred reaction vessel equipped with a backflow condenser,
In the mechanical seal flushing water line at the bottom of the reaction tank,
A polymerization method for vinyl chloride, wherein a line for introducing a polymerization inhibitor is provided together with a pressure pump.

[0006]

DETAILED DESCRIPTION OF THE INVENTION The method of the present invention is applied to the polymerization of vinyl chloride or the copolymerization or graft polymerization containing vinyl chloride as a main component. The monomer to be copolymerized with vinyl chloride is not particularly limited as long as it is a monomer usually used for copolymerization of vinyl chloride.For example, vinyl acetate, vinyl caproate, vinyl laurate, vinyl stearate such as vinyl stearate, Olefins such as ethylene, propylene, butene and isobutylene, vinyl ethers such as isobutyl vinyl ether, octyl vinyl ether, dodecyl vinyl ether and phenyl vinyl ether, halogenated olefins such as vinylidene chloride, vinyl fluoride, propylene chloride and vinyl bromide, and ethyl acrylate Acrylates or methacrylates such as n-butyl acrylate, n-butyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, and stearyl acrylate; Examples include crylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, itaconic anhydride, acrylonitrile, methacrylonitrile, and the like. One or more of these may be used, but they are used at 15% by weight or less based on vinyl chloride. Is preferred.

The graft polymerization can be carried out by a known graft polymerization method in which vinyl chloride is graft-polymerized to the polymer, and the polymer used in this case is, for example, ethylene-vinyl acetate copolymer (EVA), Ethylene-ethyl acrylate copolymer, chlorinated polyethylene, polyurethane, butadiene-styrene-methyl methacrylate (MBS), butadiene-acrylonitrile-styrene copolymer (ABS), polybutyl acrylate, butyl rubber, polystyrene, styrene-butadiene copolymer Coalescence is exemplified.

In the method of the present invention, a polymerization initiator usually used for polymerization of vinyl chloride, particularly an oil-soluble radical initiator, is used as a polymerization initiator, and examples thereof include diisopropyl peroxydicarbonate, dioctyl peroxydicarbonate, and the like. Dilauryl peroxy dicarbonate, dimyristyl peroxy dicarbonate, dicetyl peroxy dicarbonate, ditertiary butyl peroxy dicarbonate, di (ethoxyethyl) peroxy dicarbonate, di (methoxy isopropyl) peroxy dicarbonate, Di (3-methoxybutyl) peroxydicarbonate, di (3-methoxy-3-methylbutyl) peroxydicarbonate, di (butoxyethyl) peroxydicarbonate, di (2-isopropoxyethyl) peroxydicarbonate Peroxycarbonates such as di (2-isopropoxyethyl) peroxydicarbonate, dibenzylperoxydicarbonate, dicyclohexylperoxydicarbonate, ditertiarybutylcyclohexylperoxydicarbonate, and tertiarybutylperoxyneo Decanate, amyl peroxyneodecanate, tertiary octyl peroxyneodecanate, α-cumylperoxyneodecanate, tertiary butyl peroxypivalate, amyl peroxypivalate, tertiary octyl peroxypivalate, α-cumyl peroxytoluene pivalate, perhexyl oxalate, ditertiary butyl peroxy oxalate, acetylcyclohexylsulfonyl peroxide, 1,1,3,3-tetrame Peresters such as butyl peroxy phenoxy acetate, lauroyl peroxide, hexa decanoyl peroxide diisobutyl peroxide, 2-ethylhexyl, 3,
Diacyl peroxides such as 5,5-trimethylhexanoyl peroxide, 2,2′-azopisisobutyronitrile, 2,2′-azobis-2,4-dimethylvaleronitrile, 2,2′-azobis-4 Examples thereof include azo compounds such as -methoxy-2,4-dimethylvaleronitrile and the like, and these can be used in combination of several kinds as usual.

[0009] It is recommended to use a combination of these to make the polymerization reaction rate uniform and to charge the reactor with a pump. These polymerization initiators may be used as they are, may be used in a water emulsion or water suspension, or may be used after being dissolved in a solvent such as toluene.

In the method of the present invention, a known dispersant commonly used in polymerization of vinyl chloride can be used. Examples of the dispersant include completely saponified or partially saponified polyvinyl alcohol, methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and the like. Examples include synthetic polymer compounds such as hydroxypropylcellulose, hydroxypropylmethylcellulose, carboxymethylcellulose, polyvinylpyrrolidone, maleic anhydride-vinyl acetate copolymer, and natural polymer substances such as starch and gelatin, and combinations of two or more thereof. And other known dispersants.

The mechanical seal in the present invention is a method of sealing a stirring shaft, and is a method generally used together with a gland seal and an oil seal, and mainly includes a rotating ring and a shaft sealing box which rotate integrally with a stirring shaft. And a stationary ring fixed to the shaft seal box, and are slidably sealed at both end surfaces of the rotating ring and the stationary ring. In this mechanical seal, the water that is press-fitted to prevent the vinyl chloride resin powder generated during the polymerization reaction from clogging the clearance of about 1 mm between the stirring shaft and the mechanical seal casing is called mechanical seal flushing water. It also has the function of removing heat.

The important polymerization inhibitor line in the present invention comprises a tank for the polymerization inhibitor, a pressurizing pump and its line. In the event of an abnormal reaction, the polymerization inhibitor is pressed into the mechanical seal flushing water line using the pressurizing pump. By doing so, the polymerization inhibitor is added to the system together with the mechanical seal flushing water or alone. Here, with the pressurized pump, reciprocating type, rotary type, generally known things such as turbine type can be used, and the pump capacity such as flow rate is
It is arbitrarily selected depending on the size of the reaction tank and the like.

Further, since the pressure of about 15 kg / cm ² G is applied to the mechanical seal flushing water line in which the polymerization inhibitor line is provided, the pressure pump capacity of the polymerization inhibitor line provided in the middle of the line is 20 kg / cm 2. It is desirably ² G or more, preferably 25 kg / cm ² G or more. In order to further enhance the reliability, a facility for applying a back pressure to the polymerization inhibitor using an inert gas such as nitrogen may be provided.
In this case, the operation of adding the polymerization inhibitor may be either manual or automatic control by sensing pressure or temperature. It is also possible to use a polymerization inhibitor pot and a polymerization inhibitor line which are generally installed at the top of the reaction tank.

The following are examples of the polymerization inhibitor used in the present invention. For example, 2,2-di (4'-hydroxyphenyl) propane, hydroquinone, p-methoxyphenol, t-butylhydroxyanisole, n-octadecyl-3- (4-hydroxy-3,5
-Di-t-butylphenyl) propionate, 2,5-di-t-butylhydroquinone, 4,4'-butylidene-bis (3-methyl-6-t-butylphenol), 3,5-di-t-butyl -4-hydroxytoluene, 2,2'-methylene-bis (4-ethyl-6-t-butylphenol), triethylene glycol-bis [3- (3-t-butyl-5-
Methyl-4-hydroxyphenyl) propionate],
Pentaerythrityl-tetrakis [3- (3,5-di-t-
Butyl-4-hydroxyphenyl) propionate], t
Phenolic compounds such as -butylcatechol, 4,4'-thio-bis (6-t-butyl-m-cresol), tocopherol, nordihydroguaiaretic acid: phenylnaphthylamine, N, N'-diethylhydroxylamine,
N, N'-diphenyl-p-phenylenediamine, 4,4 '
Bis (dimethylbenzyl) diphenylamine, semicarbazide, semicarbazide hydrofluoride, hydrochloride, nitrate, acid sulfate, sulfate, chlorate, formate, acid oxalate, acid maleate and maleate; Derivatives of semicarbazide such as 1-acetylsemicarbazide, 1-chloroacetylsemicarbazide, 1-dichloroacetylsemicarbazide, 1-benzoylsemicarbazide, semicarbazone, carbohydrazide, thiosemicarbazide and thiosemicarbazone and the like, derivatives thereof, thiocarbazide and the like Amine compounds such as derivatives of nitroanisole; nitro compounds such as nitroanisole, N-nitrosodiphenylamine, nitroaniline, N-nitrosophenylhydroxylamine ammonium salt; triphenylphosphite, diphenylisodecylpho Phosphite, phenyl diisodecyl phosphite, 4,4'-butylidene - bis (3
Phosphorus-based compounds such as -methyl-6-t-butylphenyl-di-tridecyl) phosphite, cyclic neopentanetetraylbis (octadecylphosphite), tris (nonylphenyl) phosphite, and tris (dinonylphenyl) phosphite Compounds: unsaturated hydrocarbon compounds such as styrene, 1,3-hexadiene, α-methylstyrene, etc.
Dilauryl thiodipropionate, dimyristyl thiodipropionate, distearyl thiodipropionate,
And thio compounds such as dodecyl mercaptan and 1,3-diphenyl-2-thiourea. These can be used alone or
Used in combination of two or more.

When adding these polymerization inhibitors, it is possible to use pure ones as well as pure ones by dissolving them in a solvent. Examples of the solvent used here include water, toluene, xylene, and trichlene. The concentration of the polymerization inhibitor solution when used is in the range of 100% to 1% depending on its reactivity or properties. Is possible. If these concentrations are less than 1%, it takes too much time to add an amount necessary for terminating the reaction, and it is impossible to respond to urgency.

The amount of addition is determined by the amount of the monomer used, and 0.000.00 parts by weight based on 100 parts by weight of vinyl chloride.
It is 2 to 10 parts by weight, preferably 0.01 to 5 parts by weight. If the addition amount is less than 0.002 parts by weight, no polymerization inhibiting effect is exhibited, and even if it exceeds 10 parts by weight, a larger reaction stopping effect cannot be obtained. Further, the injection rate of these polymerization inhibitors can be arbitrarily set by a pressure pump.

In the present invention, the reaction vessel used for the polymerization of vinyl chloride is not particularly limited, but it is important that the polymerization suspension is constantly stirred even in abnormal times. The reaction vessel needs to be a bottom stirring type reaction tank having stirring power and stirring blades at the bottom of the tank.

The shape of the stirring blade can be used as long as it is generally used, and examples thereof include an anchor, a turbine, a paddle, a front door, and a blue margin blade. Furthermore, there is no limitation on the size of the wing or the number of stages.

[0019]

The present invention will be described below in detail with reference to examples. However, this embodiment is merely illustrative, and the present invention is not limited thereto. The reaction stopping ability of the polymerization inhibitor is such that the internal pressure of the reaction tank is 7 kg /
The time required to reach cm ² G was measured and evaluated.

Polymerization Example 1 of Vinyl Chloride In a stirred bottom reactor equipped with a backflow condenser having an internal volume of 24 m ³ , 9 t of deionized water, 400 ppm of polyvinyl alcohol having a polymerization degree of 700 and a saponification degree of 71 mol% as a dispersant (400 ppm) Weight based on vinyl chloride monomer, the same applies hereinafter), degree of polymerization 2
000, polyvinyl alcohol 25 with a saponification degree of 80 mol%
After charging 0 ppm, the air inside the reaction tank was removed by a vacuum pump. Next, 8.7 of the vinyl chloride monomer was used.
t, a water-based emulsion of 60% by weight of di-2-ethylhexyl peroxydicarbonate as a polymerization catalyst 330 p
pm (pure amount of catalyst based on the weight of vinyl chloride monomer,
The same applies hereinafter) and 150 ppm of an aqueous emulsion of α-cumyl peroxyneodecanoate having a purity of 50% by weight were pumped. The reaction temperature was raised to 57.5 ° C. to start the polymerization reaction. When the polymerization reaction was performed at 8.4 kg / cm ² G, the pressure in the reaction tank was increased to 7 kg / cm ² G after 4 hours from the start of the temperature rise.
Down to Then, the unreacted monomer was recovered, the obtained polyvinyl chloride slurry was transferred to a slurry tank, passed through a stripping tower, and then dried to obtain polyvinyl chloride.
The yield was 85%.

Example 1 A polymerization reaction was started in the same manner as in the above-mentioned polymerization example 1 of vinyl chloride. However, no abnormality was found in the catalyst charging pump, and usually 150 ppm of α-cumyl peroxy When inserting the neodecanoate water emulsion, about 2
Since 180 ppm of 0% increase was charged, the internal temperature started to rise and the internal pressure rose to 11.0 kg / cm ² G, resulting in an abnormal reaction. The polymerization inhibitor line was connected to the mechanical seal flushing water line. 10 kg of a 45% toluene solution of t-butylcatechol was injected into the reaction suspension over about 4 minutes. The rise in the internal temperature was gradually alleviated from 30 seconds after the start of the injection of the polymerization inhibitor, but tended to decrease with the internal pressure when the injection was continued and the injection was completed. Thereafter, it took 24 minutes for the internal pressure to drop to 7 kg / cm ² G, but the reaction stopped safely.

[0022]

Industrial Applicability The present invention relates to the injection of a polymerization inhibitor into an active reaction suspension in a system in an abnormal reaction in a polymerization reaction tank.
Since the diffusion can be reliably performed, there is an industrial advantage that the rise in temperature and pressure is effectively suppressed, the safety of the manufacturing equipment is improved, and the productivity is improved by stable operation.

[Brief description of the drawings]

FIG. 1 is an explanatory view of a bottom stirring type reaction tank provided with a polymerization inhibitor line in addition to a mechanical seal flushing water line according to the present invention.

FIG. 2 is an enlarged detailed view of a stirring unit in FIG.

[Explanation of symbols]

 1. Backflow condenser 2. Reaction tank 3. Jacket 4. Stirrer blade 5. Discharge line 6. 6. Polymerization inhibitor tank 7. Pressurizing pump for polymerization inhibitor 8. Polymerization inhibitor line 9. Mecha seal flushing water line Stirrer 11. Casing 12. Sealing 13. Stirring shaft 14. Fixed ring 15. Rotating ring

Claims (1)

[Claims] 1. A method for suspension polymerization of vinyl chloride using a jacketed bottom-stirred reaction tank equipped with a backflow condenser, wherein a pressure line for introducing a polymerization inhibitor is provided to a mechanical seal flushing water line at the bottom of the reaction tank. A method for polymerizing vinyl chloride, comprising: