JPH09168735A - Reaction apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent adhesion within a reaction tank in a case used in suspension reaction, especially, suspension polymerization and to simply perform the repairing thereof on the spot by covering a stirring blade with a fluoroplastic shrink tube. SOLUTION: A stirring blade 2 is covered with a fluoroplastic shrink tube 1. The shrink tube 1 has a characteristic shrinking from an initial state by a temp. change and a heat shrinkable tube is pref. As a method for covering the shrink tube, a known method, for example, a method inserting the stirring blade into the shrink tube and subsequently spraying hot air on the shrink tube from the periphery thereof or a method inserting the stirring blade into the shrink tube and subsequently injecting a liquid into the shrink tube by a polymerization reaction apparatus to raise the temp. thereof is employed. By using this reaction apparatus, the adhesion of a polymer can be suppressed. Further, when the deterioration of the fluoroplastic shrink tube is confirmed, the fluoroplastic shrink tube can be simply replaced on the spot.

Description

Detailed Description of the Invention

[0001]

TECHNICAL FIELD The present invention relates to a reaction apparatus useful for preventing adhesion, which is a problem when performing a reaction in which solid matters are present during and / or after the reaction. Further, the present invention relates to a reaction apparatus equipped with a stirring blade and a baffle plate, which are suitable for producing a super absorbent polymer by suspension polymerization, and are covered with a fluororesin shrink tube.

[0002]

2. Description of the Related Art In a reaction in which a solid substance is present during and / or after the reaction, if the solid substance adheres to a stirring blade or the like, it is necessary to remove the adhered substance, resulting in a decrease in productivity. / Brings down quality due to contamination. For example, in suspension polymerization, the adhesion of the produced polymer particles to the polymerization reaction device causes a decrease in heat transfer efficiency, a decrease in productivity due to removal of adhering substances, and a decrease in quality due to peeling / mixing of adhering substances.

In recent years, when water-absorbing and water-retaining properties are utilized to produce by superposition polymerization a highly water-absorbent resin which is widely used in the medical field such as sanitary materials, the food industry field and the agricultural field. In addition to causing the deterioration of quality due to the inclusion of the deposit in the product, it takes a lot of labor and time to peel the deposit from the polymerization reactor.

As a technique for preventing adhesion in suspension polymerization, a method of applying a material having excellent releasability to the surface of a reactor in advance is often used. Japanese Patent Publication No. 2-14361 discloses a method of coating a stirring blade with Teflon resin as a countermeasure against adhesion. Although this formula is certainly effective, the coating surface becomes rough with the prolongation of production, and the effect is reduced. In that case, repairing at the site is almost difficult, and there is a problem that disassembling, recoating, and assembling of the equipment are required, and the cost thereof is also expensive.

On the other hand, Japanese Patent Laid-Open No. 6-79213 discloses that
As a method of coating a dispensing nozzle with a Teflon resin, there is a description that a shrink tube is used. However, the method is intended to prevent a liquid coating agent or the like from adhering to the dispensing nozzle to form a liquid pool, and the material of the resin is particularly limited as long as it is water repellent. Not a thing. Furthermore, the adhesion of solid matter existing during or after the reaction does not pose a problem.

[0006]

SUMMARY OF THE INVENTION The present invention has been made to solve such problems, and it is a suspension system reaction,
Especially when used for suspension polymerization, it is an object of the present invention to provide a reaction apparatus capable of preventing adhesion in a reaction tank for a long period of time and easily repairing it on site.

[0007]

[Means for Solving the Problems] The present inventors have completed the present invention by paying attention to a fluorine-based shrinkable tube.

That is, the gist of the present invention is: (1) In a reaction apparatus which is used for a reaction in which a solid substance is present during and / or after the reaction, and which has a stirring blade in the reaction tank, the stirring blade has a fluorine-based structure. Reactor characterized by being covered with a resin shrink tube, (2) Reactor according to the above (1), further comprising a baffle plate coated with a fluororesin shrink tube in the reaction tank, (3) Coating The fluorine-containing resin shrinkable tube having a thickness of 10 μm to 2 mm is used as the reaction device according to the above (1) or (2), and (4) any one of the above (1) to (3) used for suspension polymerization. (5) The reaction device according to any one of (1) to (4), which is used in the production of a highly water-absorbent resin, and (6) the fluororesin shrinkable tube is polytetrafluoroethylene. (PTFE , Tetrafluoroethylene - hexafluoropropylene prop Oren copolymer (FE
P), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and one or more heat shrinkable tubes selected from the group consisting of tetrafluoroethylene-ethylene copolymer (ETFE) (1) to (5) The reactor according to any one of the above.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION The reaction apparatus of the present invention is used for a reaction in which a solid substance is present during and / or after the reaction (hereinafter referred to as “suspension system reaction”), and is equipped with a stirring blade in the reaction tank. In the reactor described above, the stirring blade is covered with a fluororesin shrink tube. Here, when the reaction apparatus of the present invention is provided with a baffle plate in the reaction tank, it is preferable that the baffle plate is also covered with the fluororesin shrink tube.

Examples of such suspension reaction include a reaction in which a solid substance is present before the start of the reaction and a reaction in which a solid substance is generated during the reaction. Examples thereof include catalytic reaction, seed polymerization, surface cross-linking reaction of water absorbent resin, modification of natural polymer and the like. Moreover, examples of the method include suspension polymerization, precipitation polymerization, and reactions involving crystallization. Further, in the suspension reaction of the present invention, solid-liquid mixing operation in which solid matter exists, crystallization accompanying concentration operation, specifically crystallization by evaporative concentration, crystallization without concentration operation, specifically Includes operations such as crystallization separation and extraction operation. Among them, it is particularly preferably used for suspension polymerization. Furthermore, it can be suitably used for a suspension polymerization reaction when producing a super absorbent polymer.

Further, as long as it is a reaction apparatus provided with at least a stirring blade in the reaction tank, the shape and type of the reaction tank, and additional devices such as a heating device and a condenser are not particularly limited, and are generally known. A reactor is used.

As the fluorine-based resin constituting the shrinkable tube, polytetrafluoroethylene (PTFE), tetrafluoroethylene-hexafluoropropionene copolymer (FEP), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA). ), Tetrafluoroethylene-ethylene copolymer (ETFE), etc. are preferable, but not limited to a single resin, they may be a composite or combination of these, or a composite with another resin. From the viewpoint of non-adhesiveness, FEP and PFA are preferable. The non-adhesive property means that even a sticky substance having strong adhesiveness is easily released and does not adhere or hardly adheres. Further, PFA is more preferable from the viewpoint of heat resistance.

As the resin used in the composite,
A known resin can be used without particular limitation as long as it is inert to the reaction, the reaction raw materials and the like. For example, resins such as polyimide, polyamide-imide, urethane, acryl, epoxy and silicon can be used.

The shrinkable tube in the present invention is a tube having a characteristic that it shrinks more than in the initial state due to temperature change and the like, and a heat shrinkable tube is preferable from the viewpoint of simplicity of coating. The shrinkable tube has a shrinkage rate of 10 to 10.
30%, thickness after coating by shrinkage is 10 μm to 2
mm is preferred. If it is 10 μm or less, durability is weak, and if it is 2 mm or more, uniform shrinkage is difficult and adhesion of the stirring blade and the baffle plate to the base material is weak, which is economically disadvantageous. The fluororesin shrink tube as described above,
Various materials, shapes, and sizes are commercially available, and can be appropriately used according to the shape of the stirring blade.

As a method for covering the shrinkable tube, a known method can be adopted. For example, after inserting a shrinkable tube into a portion to be covered, a method of uniformly blowing hot air at 50 to 200 ° C. from the surroundings to bring it into close contact, or after inserting into a shrinkable tube into a portion to be covered, a liquid is injected into a polymerization reaction device,
It is a method of raising the temperature to 200 ° C. and bringing them into close contact.

The shrink tube may be used as it is, or if it is difficult to insert the shrink tube, a short tube may be used. Further, the number of shrinkable tubes may be one or plural depending on durability.

There is no limitation on the base material of the stirring blade and the baffle plate, and examples thereof include metals such as stainless steel, titanium, and Hastelloy, and nonmetals such as glass, ceramics, and resins. In the present invention, the stirring blade refers to a stirring shaft and a stirring blade, if the shrinkable tube can be inserted, regardless of the blade shape, conventionally known stirring blade can be used, for example, propeller, turbine blade, Paddle wings, anchor wings, Faudler wings, etc. may be mentioned.

As the baffle plate, a conventionally known baffle plate can be used as long as a shrinkable tube can be inserted therein, and examples thereof include baffle plates such as flat plates, round bars, and fingers.

As described above, the reaction apparatus of the present invention can be suitably used for the suspension polymerization reaction particularly in the production of the super absorbent polymer. In the following, the case of carrying out such suspension polymerization reaction will be exemplified. Now, the details will be described. In the present invention,
When the superabsorbent polymer is produced by suspension polymerization, reverse phase suspension polymerization is used. Here, the reverse-phase suspension polymerization refers to carrying out polymerization by suspending a water-soluble polymerizable monomer in a hydrophobic organic solvent that is inert to the polymerization.

The water-soluble polymerizable monomer is preferably an olefinic unsaturated carboxylic acid and its salt, an olefinic unsaturated phosphoric acid and its salt, an olefinic unsaturated carboxylic acid ester, an olefinic unsaturated sulfonic acid and Examples thereof include vinyl monomers having a polymerizable unsaturated group such as salts thereof, olefinically unsaturated amines, olefinically unsaturated ammonium salts, and olefinic amides.
Of these, in the present invention, an olefinically unsaturated carboxylic acid or a salt thereof can be preferably used.

Examples of the above-mentioned olefinic unsaturated carboxylic acid or salt thereof include acrylic acid, methacrylic acid, maleic acid, fumaric acid, and alkali salts thereof. Examples of the olefinic unsaturated carboxylic acid ester include methoxy polyethylene glycol (meth) acrylate, phenoxy polyethylene glycol (meth) acrylate, and hydroxyethyl (meth) acrylate. Examples of the olefinically unsaturated sulfonic acid or salt thereof include (meth) acrylamidomethylpropane sulfonic acid, allyl sulfonic acid, and alkali salts thereof. Examples of the olefinically unsaturated phosphoric acid or salt thereof include (meth) acryloyl (poly) oxyethylene phosphoric acid ester, and alkali salts thereof. Examples of the olefinically unsaturated amine include dimethylaminoethyl (meth) acrylate. Examples of the olefin unsaturated ammonium salt include (meth) acryloyloxyethylene trimethyl ammonium halogen salt and the like. Examples of the olefinically unsaturated amide include (meth)
Examples thereof include (meth) acrylamide derivatives such as acrylamide, methyl (meth) acrylamide, ethyl (meth) acrylamide, propyl (meth) acrylamide, and vinylmethylacetamide. These substances can be used alone or as a mixture of two or more. Moreover, as said alkali salt, an alkali metal salt, an alkaline earth metal salt, an ammonium salt, etc. are mentioned.

The concentration of the water-soluble polymerizable monomer in the aqueous solution of the water-soluble polymerizable monomer is preferably 1
˜70% by weight, more preferably 10 to 60% by weight. Examples of the hydrophobic organic solvent inert to polymerization used in the present invention include n-pentane, cyclopentane, and n-pentane.
Aliphatic hydrocarbons such as hexane, cyclohexane, n-heptane and methylcyclohexane, aromatic hydrocarbons such as benzene and toluene, n-butyl alcohol and n-
Examples thereof include C 4-6 aliphatic alcohols such as amyl alcohol, aliphatic ketones such as methyl ethyl ketone, and aliphatic esters such as ethyl acetate. These can be used alone or as a mixture of two or more kinds. The amount of the hydrophobic organic solvent used is preferably in the range of 50 to 500% with respect to the weight of the aqueous solution of the water-soluble polymerizable monomer.

Upon suspension polymerization, it is preferable to add a dispersant to the polymerization system. Such a dispersant is not particularly limited as long as it has the ability to stably disperse a water-soluble polymerizable monomer in a hydrophobic organic solvent, but, for example,
Fatty acid esters such as sorbitan monostearate and sorbitan monolaurate; cellulose ethers such as ethyl cellulose and ethyl hydroxyethyl cellulose; cellulose esters such as cellulose acetate, cellulose butyrate and cellulose acetate butyrate, alkyl sulfates, polyoxyethylene alkyl ether sulfates. Ester, alkyl glyceryl ether, polyoxyethylene alkyl ether sulfosuccinate,
Examples thereof include anionic surfactants such as alkylsulfosuccinamide and α-sulfofatty acid. These can be used alone or as a mixture of two or more kinds. Said,
The amount of the dispersant used is effective even if the amount is small, and is preferably 0.01 to 10 with respect to the water-soluble polymerizable monomer.
%, And more preferably 0.02 to 5% by weight.
If the amount used is less than 0.01%, the effect is difficult to develop,
It is not preferable to use more than 10% by weight because it is economically disadvantageous.

Examples of the method for suspension-polymerizing the water-soluble polymerizable monomer using the aqueous solution of the hydrophobic organic solvent and the water-soluble polymerizable monomer include the following methods. A method of sequentially polymerizing while supplying an aqueous solution of a water-soluble polymerizable monomer into a hydrophobic organic solvent (sequential polymerization method). A method of preliminarily dispersing a mixed solution obtained by previously mixing and dispersing an aqueous solution of a water-soluble polymerizable monomer with a part of a hydrophobic organic solvent while supplying it to the hydrophobic organic solvent. A method using the above items in combination.

A polymerization initiator is preferably used in the above polymerization. The polymerization initiator is not particularly limited as long as it is a water-soluble radical polymerization initiator, and examples thereof include ketone peroxides such as methyl ethyl ketone peroxide and methyl isobutyl ketone peroxide; di-t-butyl. Dialkyl peroxides such as peroxides and t-butylcumyl peroxide; t
-Alkyl peroxy esters such as butyl peroxyacetate, t-butyl peroxyisobutyrate, and t-butyl peroxypivalate; persulfates such as hydrogen peroxide, potassium persulfate, and ammonium persulfate; perchloric acid Perchlorates such as potassium and sodium perchlorate; halogenates such as potassium chlorate and potassium bromate; 2- (carbamoylazo) -isobutyronitrile, 2,2′-azobis (N, N '-Dimethyleneisobutylamidine) dihydrochloride, 2,2'-azobis (2-amidinopropane) dihydrochloride, 2,2'
-Azobis (N, N'-dimethyleneisobutylamidine), 4,4'-azobis (4-cyanopentanoic acid), azobisisobutyronitrile, 2,2'-azobis (4-methoxy-2, 4-dimethylvaleronitrile), (1-phenylethyl) azodiphenylmethane,
Dimethyl-2,2'-azobisisobutyrate, 2,
2′-azobis (2-methylbutyronitrile), 1,
1'-azobis (1-cyclo-hexanecarbonitrile), 2,2'-azobis (2,4,4'-trimethylpentane), 2-phenylazo-2,4-dimethyl-4
Examples thereof include -methoxyvaleronitrile, and azo compounds such as 2,2'-azobis (2-methylpropane). These can be used alone or as a mixture of two or more kinds.

The amount of the polymerization initiator used is usually 0.01 to 10% by weight based on the water-soluble polymerizable monomer,
It is preferably 0.02 to 5% by weight. The method of adding the polymerization initiator is not particularly limited, but it is preferably added in advance to the aqueous solution of the water-soluble polymerizable monomer.

The polymerization temperature in the above polymerization is usually from 20 to
A range of 120 ° C, preferably 40 to 100 ° C is suitable. If the polymerization temperature exceeds 120 ° C., the degree of crosslinking will be extremely high, so that the water absorbing ability of the water absorbent resin obtained will decrease,
When the polymerization temperature is lower than 20 ° C, the polymerization rate is extremely reduced, which is not preferable.

In the present invention, as the polymerizable monomer, it is preferable to use only the above-mentioned water-soluble polymerizable monomer for homopolymerization or copolymerization, but it is possible to copolymerize with the water-soluble polymerizable monomer. Water-insoluble monomer,
For example, an alkyl group having 1 to 22 carbon atoms, acrylic acid,
An ester monomer or the like with an unsaturated carboxylic acid such as methacrylic acid, maleic acid or fumaric acid can also be used in an amount of 50% by weight or less based on the total weight of the monomers.

Besides the above-mentioned hydrophobic organic solvent, an amphipathic solvent may be added within a range not exceeding the amount of the hydrophobic solvent used. Examples of the amphipathic solvent include alcohols such as methanol, ethanol, propanol, and 2-propanol, ketones such as acetone, tetrahydrofuran, and ethers such as dioxane.

In the present invention, a known crosslinking agent may be added to the polymerization system before, during or after the polymerization. Examples of the cross-linking agent include polyallyl compounds such as N, N-diallyl (meth) acrylamide, diallylamine, diallyl phthalate, diallyl malate, diallyl terephthalate, triallyl cyanurate, and triallyl phosphate; divinylbenzene,
Polyvinyl compounds such as N, N-methylenebisacrylamide, ethylene glycol diacrylate, ethylene glycol dimethacrylate, and glycerin trimethacrylate; ethylene glycol diglycidyl ether,
Polyglycidyl ethers such as polyethylene glycol diglycidyl ether and polyglycerin polyglycidyl ether; haloepoxy compounds such as epichlorohydrin and α-methylchlorohydrin; polyaldehydes such as glutaraldehyde and glyoxal; polyols such as glycerin; ethylenediamine etc. A polyvinylamine such as 2-hydroxyethylmethacrylate; and an inorganic salt producing a polyvalent ion such as calcium, magnesium, zinc, or aluminum;
Or an organic metal salt can be mentioned.

A modifier such as polyoxyethylene alkylphenyl ether may be added to the polymerization system. In this case, the amount of the modifier used depends on the desired properties of the water absorbent resin of the final product. However, it is preferably 0.01 to 10% by weight based on the water-absorbent resin that is usually produced.

[0032]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited to these Examples and the like.

Example 1 408.0 g of acrylic acid was diluted with 102.0 g of water,
30% by weight aqueous sodium hydroxide solution 54 while cooling
After neutralization with 4.0 g, 2.9 wt% potassium persulfate 5
6.1 g was added to make a uniform solution, and a monomer / initiator mixed aqueous solution was prepared. Separately, a reflux cooling dehydration tube, a dropping funnel, a nitrogen introducing tube, and a stainless steel stirring blade covered with a PFA heat shrink tube (Gunze Co., Ltd. GF tube) as shown in FIG. 1 (thickness 300 μm) were provided. In a 5 liter separable flask, cyclohexane 1248.1.
After charging g, polyoxyethylene dodecyl ether sulfuric acid ester sodium salt (average ethylene oxide addition mole number = 2, Emal E-27C, manufactured by Kao Corporation) 27
After 6.5 g of a wt% aqueous solution was added and the mixture was stirred at a rotation speed of 300 rpm, the inside of the reactor was replaced with nitrogen, the temperature was raised to the boiling temperature, and 4.1 g of water was removed by a reflux condenser. The above-mentioned monomer / initiator mixed aqueous solution was supplied into this cyclohexane over 60 minutes, and after the completion of the supply, stirring was continued under reflux for 2 hours for polymerization. Polymer particles of the resin were generated during the polymerization, but when confirmed after the completion of the polymerization, adhesion of the stirring blade was not observed at all. Also, the PFA shrink tube could be easily removed with a cutter knife.

Example 2 The same as Example 1 except that the stirring blade was covered with a FEP heat-shrinkable tube (GF tube manufactured by Gunze Co., Ltd.) which was sliced as shown in FIG. Polymerization was carried out using the method. After the completion of the polymerization as in Example 1, no adhesion of stirring blades was observed. Also, the FEP shrink tube could be easily removed with a cutter knife.

Comparative Example 1 Polymerization was carried out in the same manner as in Example 1 except that the stainless paddle blade was used as the stirring blade as it was. After the completion of the polymerization, strong adhesion of the resin solid matter was recognized on the shaft and the blade, and the adhesion amount after drying was 7.0 g.

Comparative Example 2 Polymerization was performed in the same manner as in Example 1 except that a buffing (# 400) stainless steel paddle blade was used for the stirring blade. After the completion of the polymerization, strong adhesion of the resin solid matter was recognized on the shaft and the blade, and the adhesion amount after drying was 6.4 g.

Comparative Example 3 Polymerization was carried out in the same manner as in Example 1 except that the stirring blade was subjected to electrolytic polishing. After the completion of the polymerization, strong adhesion of the resin solid matter was recognized on the shaft and the blade, and the adhesion amount after drying was 8.0 g.

Comparative Example 4 Polymerization was carried out in the same manner as in Example 1 with the stainless paddle blade used in Comparative Example 1 being in two stages. After the completion of the polymerization, strong adhesion of the resin solid matter was recognized on the shaft and the blade, and the adhesion amount after drying was 20.0 g.

[0039]

[Table 1]

[0040]

By using the reaction apparatus of the present invention,
Adhesion of a polymer or the like, which has been a problem in suspension reaction, can be easily suppressed. Further, when deterioration of the fluorine-based shrinkable tube according to the present invention is recognized as the production is prolonged, the fluorine-based shrinkable tube can be easily removed on site and replaced with a new fluorine-based shrinkable tube. In addition, it is possible to improve productivity by reducing costs, which was a problem, and shortening the facility downtime.

[Brief description of the drawings]

FIG. 1 shows a diagram of a stirring blade covered with a fluorine-based shrinkable tube in Example 1 of the present invention.

FIG. 2 shows a diagram of a stirring blade covered with a fluorine-based shrinkable tube in Example 2 of the present invention.

[Explanation of symbols]

 1 Fluorine-based resin shrink tube 2 Stirring blade 3 Stirring shaft 4 Stirring blade

Claims (6)

[Claims] 1. A reactor used for a reaction in which a solid substance is present during and / or after the reaction and having a stirring blade in a reaction tank, wherein the stirring blade is covered with a fluororesin shrink tube. A reactor characterized by. 2. The reaction apparatus according to claim 1, further comprising a baffle plate covered with a fluororesin shrink tube in the reaction tank. 3. The reactor according to claim 1, wherein the coated fluororesin shrink tube has a thickness of 10 μm to 2 mm. 4. The reaction apparatus according to claim 1, which is used for suspension polymerization. 5. The reaction apparatus according to claim 1, which is used for producing a highly water-absorbent resin. 6. A fluororesin shrinkable tube comprising a polytetrafluoroethylene (PTFE), a tetrafluoroethylene-hexafluoropropionene copolymer (FE
P), tetrafluoroethylene-perfluoroalkyl vinyl ether copolymer (PFA), and tetrafluoroethylene-ethylene copolymer (ETFE), which is one or more heat-shrinkable tubes selected from the group consisting of:
5. The reaction device according to any one of 5 to 5.