WO2003040191A1 - Method of producing hydrophilic polymer - Google Patents

Abstract

In a method of producing a hydrophilic polymer by continuously feeding an aqueous solution (26) of vinyl type monomer onto the upper surface of a movable belt (2) and polymerizing the monomer, the continuous belt (2) is formed with a downwardly projecting flexure portion (100), which is the deepest in the vicinity of polymerizing section for the vinyl type monomer, along the direction of travel of the continuous belt, and the polymerization of the vinyl type monomer is started in the flexure portion. Further, the water vapor volatilizing from the surface of the aqueous solution of vinyl type monomer for which polymerization has been started is expelled.

Description

 Method for producing hydrophilic polymer

 The present invention relates to a method for producing a Biel-based hydrophilic polymer suitable for use as a polymer flocculant, a water absorbing resin, various dispersants, and the like, particularly suitable for use as a polymer flocculant. More specifically, when polymerizing a vinyl-based monomer, the depth of the aqueous solution of vinyl-based monomer can be increased to 50 mm or more, and thus a hydrophilic polymer suitable for mass production of hydrophilic polymer. It relates to the manufacturing method. Background art

 Vinyl-based hydrophilic polymers obtained by polymerizing vinyl-based water-soluble monomers of acrylic acid, acrylic acid, dimethylaminoethyl methacrylate and tertiary salt of quaternary ammonium salt are various wastewaters. It is widely used in processing, papermaking aids and water-absorbent resins.

 Methods of producing these hydrophilic polymers include a batch system and a continuous system.

 As the notch type, for example, there is a manufacturing method described in Japanese Patent Application Laid-Open No. 11- 2 2 8 0 9. However, batch-type manufacturing methods are not suitable for mass production.

On the other hand, there is a method for continuously producing a hydrophilic polymer for the purpose of mass production. In this method, the polymerization operation of the water-soluble monomer is usually performed on a continuous belt. Even in a continuous production method in which an aqueous solution of vinyl-based water-soluble monomer (hereinafter simply referred to as a monomer) is polymerized on a continuous belt, hydrophilic polymers having different monomer compositions at the start of production or At the time of brand switching, etc., in which the manufacturing brand is switched to the brand, it is necessary to fill the aqueous monomer solution on the belt prior to the start of polymerization. Conventionally, a removable temporary tacking weir is provided in the middle of the polymerization belt, and this weir is used to hold the aqueous monomer solution on the polymerization belt. For example, Japanese Patent Application Laid-Open Nos. 2 0 0 0 0 1 0 1 7 0 0 4 and 2 — 0 0 3 3 4 3 0 5 have hydrophilicity weights that use temporary or mechanically removable tacks. A method of making the coalescence is disclosed.

 These general polymerization procedures are described. First, the gas-tight chamber through which the continuous belt passes is purged with nitrogen, and then the aqueous solution of monomer is filled in the belt of the belt while the belt is at rest. After that, light is irradiated when a photopolymerization initiator is added to the aqueous monomer solution, or a redox polymerization initiator is added to start polymerization when the catalyst is not added. After the monomer is polymerized to gel and the polymer itself functions as a weir, purge the nitrogen in the airtight chamber with air. After that, the worker removes the tacking weir by manual or mechanical means. After the air-tight chamber is again replaced with nitrogen, and the polymer-formed crucible is filled with the aqueous monomer solution, polymerization is started in the same manner as described above, and the belt is rotated continuously from then on. Polymerize.

However, since the above method needs to stop the reaction before starting the continuous operation, remove the temporary fixing rod, and then start the polymerization again to shift to the continuous operation. Workability is bad. Furthermore, monomers used in the production of hydrophilic polymers, particularly monomers used in the production of flocculants, are susceptible to polymerization inhibition due to the presence of oxygen. For this reason, it is necessary to sufficiently replace oxygen existing in the polymerization atmosphere in advance with an inert gas such as nitrogen. Therefore, when the hydrophilic polymer is produced by the above-mentioned conventional method, after the worker manually removes the temporary fixing crucible, the substitution of oxygen with nitrogen is further applied. You need to do it in minutes. However, since this work takes a long time, especially when frequent stock changes are performed, the loss of time required for this is significant. In addition, even in the case where the tack is removed by mechanical means, if the tackiness of the obtained hydrophilic polymer is high, it may be difficult to mechanically detach the tacking tack with the polymer. . In this case, the worker needs to remove it manually. In addition, some of the monomers used in the preparation of the hydrophilic polymer may be at risk of drug injury. In this case, there is a risk that the worker may be injured by carelessness while removing the temporary tack tack.

 On the other hand, as a more preferable continuous production method of a vinyl-based hydrophilic polymer, there is a method of polymerizing a monomer by irradiating the aqueous solution of the above-mentioned monomer and the like from above the aqueous solution. In this method, when obtaining a water-soluble polymer having a high degree of polymerization as used as a polymer flocculant, there is no variation in the degree of polymerization between the upper and lower portions in the thickness direction of the polymer. In order to obtain, the following precautions are necessary.

 (1) The light energy is kept constant at the upper and lower portions of the aqueous monomer solution layer,

 (2) The heat of polymerization volatilizes water vapor from the surface of the aqueous monomer solution, whereby no concentration distribution occurs between the upper and lower portions of the aqueous monomer solution,

 (3) There is no temperature difference between the upper and lower portions of the aqueous monomer solution, and

(4) Suppressing the inhibition of the polymerization of the monomer by oxygen Conventionally, in order to avoid the above problems, the solution depth of the monomer aqueous solution is reduced to equalize the light energy between the upper and lower portions of the aqueous solution. It is like that. In addition, the rate of evaporation of water vapor from the surface of the monomer aqueous solution The above problems can be avoided by covering the monomer aqueous solution with a sheet (film) or cooling it from the outside in order to keep the temperature constant or to eliminate the temperature distribution between the upper and lower portions of the monomer aqueous solution. It is done.

 For example, in Japanese Patent Publication No. 6-804, a method of polymerizing an aqueous solution of 20 to 90% by mass of a water-soluble vinyl monomer to which a photopolymerization initiator has been added under light irradiation on a movable belt. Is proposed. In this method, a flexible band-shaped wedge is adhered to both edges of the bell wedge along the moving method of the metal movable belt, and a light transmitting film is stretched on the upper surface of the two wedges. The closed space formed by the belt, the bag and the film is filled with an aqueous monomer solution, and light is irradiated from the upper surface of the film to continuously polymerize the water-soluble vinyl monomer.

 In the above-mentioned polymerization method, since the height of the weir defines the thickness of the monomer layer, if the weir is too high, removal of the heat of polymerization becomes difficult. Further, the amount of light irradiated to the vinyl-based monomer layer is different between the upper and lower portions of the vinyl-based monomer layer. As a result, the degree of polymerization of the resulting polymer is uneven. On the other hand, when the thickness of the vinyl-based monomer layer is thin, the rate of polymer production per unit of moving belt area decreases. The above publication discloses that, in consideration of these balances, it is preferable that the height of the crucible is usually 5 to 50 mm.

 Japanese Examined Patent Publication No. H8-5926 discloses a photopolymerization device having an airtight chamber having a light-transmissive material portion at the top and a movable belt having a rubber wedge bonded to both edges of the belt. Disclosed is a method for continuously producing an acrylic polymer gel using the same.

In this method, oxygen in an aqueous solution of an acrylic monomer containing a photopolymerization initiator is adjusted to 1 mg ZL or less, and oxygen in the hermetic chamber is maintained in an atmosphere of 1 volume% or less. In this method, a synthetic resin film is continuously supplied on a movable belt, and an aqueous monomer solution is continuously supplied in a thin layer on the film, and light energy is supplied to the aqueous monomer solution. The irradiation initiates the polymerization of the monomer. Thereafter, at the stage where the polymerization proceeds and the aqueous monomer solution becomes non-flowable, the synthetic resin film is continuously supplied on the upper side of the aqueous monomer solution and brought into close contact with the surface. After further continuing the light energy irradiation, the upper and lower synthetic resin films are automatically peeled off from the surface of the polymer gel at the other end of the movable belt to continuously take out the polymer gel. There is.

 Furthermore, it is also described that the solution depth of the monomer aqueous solution to be supplied to the movable belt and subjected to polymerization is 3 to 20 mm, preferably 5 to 10 mm. However, there is no description of the reason for limiting to the said liquid depth.

 In the above two examples, flexible wedges are adhered and fixed to both edges of the continuous belt to form a reservoir of the aqueous monomer solution. In this case, raising the weir will cause excessive bending stress on the weir, resulting in breakage of the weir and separation of the weir from the belt. For this reason, the height of the ridge can not be increased without limitation, and as a result, the thickness of the resulting hydrophilic polymer becomes thin and is not suitable for mass production. Furthermore, at the start of operation of the polymerization apparatus, there is a problem that the aqueous monomer solution flows in the advancing direction of the crucible and the thickness of the obtained hydrophilic polymer fluctuates.

On the other hand, when the flexible rod is placed on the upper surface of the continuous belt, it is inevitable that the aqueous monomer solution permeates the sliding surface between the rod and the continuous belt and it flows out of the continuous belt. . Furthermore, the monomer is polymerized on the sliding surface to become highly viscous, and it is impossible to avoid an accident such as sticking between the bag and the belt. Disclosure of the invention As a result of various studies made by the present inventors to solve the above problems, the continuous belt rotating continuously is bent, and polymerization is performed while filling the vinyl monomer water solution at this bent portion, at the start of the polymerization operation or We learned that the operation at brand switching is simple and easy, and can be performed in a short time. Furthermore, by providing slopes on both edges of the continuous belt, it is possible to prevent the vinyl monomer aqueous solution from flowing out of the belt, and it becomes possible to deepen the liquid solution of the monomer aqueous solution It was found that continuous production was possible. Furthermore, in the case of producing a high molecular weight water-soluble polymer, water vapor is volatilized from the surface of the water-soluble monomer aqueous solution due to the heat of polymerization generated as the polymerization proceeds, but this volatilized water vapor is positively The present inventors have completed the present invention by finding out that, by excluding the polymer, it is possible to mass-produce a vinyl-based hydrophilic polymer having a high molecular weight and a small variation in polymerization degree and a thick film.

 Accordingly, an object of the present invention is to provide a method for mass producing a hydrophilic polymer having the above advantages.

 The present invention for achieving the above object is as follows.

 [1] A method for producing a hydrophilic polymer in which an aqueous solution of a vinyl monomer is continuously supplied to the upper surface of a movable belt to polymerize the monomer, the polymerization of the Biel monomer on the continuous belt A hydrophilic portion is characterized in that a bending portion protruding downward which is deepest in the vicinity of the portion is formed along the traveling direction of the continuous belt, and polymerization of a pinyl monomer is started in the bending portion. Method of producing a polymer

 [2] The method for producing a hydrophilic polymer according to [1], wherein an inclined portion which is inclined upward is formed at both edges of the continuous belt.

[3] The method for producing a hydrophilic polymer according to [1], wherein a bend is provided such that the solution depth of the aqueous vinyl monomer solution in the bend is 50 mm or more. [4] The method for producing a hydrophilic polymer according to [1], wherein the polymerization of the vinyl monomer is carried out by irradiating a vinyl monomer aqueous solution containing a photopolymerization initiator with light.

 [5] The obtained hydrophilic polymer is a water-soluble polymer, and the water vapor volatilized from the surface of the polymerization-initiated vinyl monomer aqueous solution is removed [1] The method for producing a hydrophilic polymer according to [1] .

 In the present invention, the flexible continuous belt is continuously deformed in the vicinity of the polymerization portion, more specifically, in the vicinity of the supply portion of the monomer aqueous solution to form a bent portion projecting downward, An aqueous vinyl monomer solution is supplied to the bent portion to polymerize. According to this method, it is not necessary to provide a tacking hook or the like in the forward direction of the belt movement at the start of the polymerization operation or at the brand change, and the polymerization operation is simplified. In addition, there is no loss of working time at the start of polymerization operation or at the time of name change. Furthermore, it is possible to completely prevent the aqueous monomer solution from flowing out of the continuous belt.

 In addition, in the photopolymerization of a vinyl-based water-soluble monomer containing a photopolymerization initiator, the irradiation amount of light is high in the vicinity of the surface of the aqueous solution of the vinyl-based monomer, and decreases with distance from the surface. Therefore, the amount of radicals generated near the surface of the vinyl monomer aqueous solution increases, and the degree of polymerization of the polymer formed near the surface decreases. On the other hand, in the part away from the surface, the amount of radical generation decreases, so the polymer formed has a high degree of polymerization.

 In the photopolymerization of the vinyl monomer aqueous solution, heat of polymerization is generated as the polymerization proceeds, and the temperature of the vinyl monomer aqueous solution rises. Therefore, the water in the vinyl monomer aqueous solution volatilizes on the surface of the vinyl monomer aqueous solution.

By forcibly removing this volatilized water vapor, the volatilization of water from the surface of the aqueous solution is actively promoted, whereby a vinyl-based unit amount is eliminated. The monomer concentration near the surface of the body aqueous solution can be increased.

 As a result, a decrease in the degree of polymerization of the polymer in the vicinity of the surface of the aqueous solution in the case of producing a high molecular weight water-soluble polymer to be used as a coagulant can be avoided. Therefore, by forcibly removing water vapor, it is possible to produce a polymer with less variation in molecular weight, even in the case of photopolymerizing a vinyl monomer aqueous solution having a solution depth of 50 cm or more. it can. Brief description of the drawings

 FIG. 1 is a schematic side view showing an example of a continuous belt used in the method for producing a hydrophilic polymer of the present invention. FIG. 2 is a schematic side view showing an example of a device for producing vinyl monomers used in the present invention. Figure 3

(a) is a schematic sectional drawing which shows an example of the airtight chamber of the manufacturing apparatus of the hydrophilic polymer used for implementation of this invention, (b) is the same perspective view. FIG. 4 is a schematic side view of a manufacturing apparatus used in a comparative example.

 2 is a continuous belt; 4 and 6 are butlers; 8 is an upper belt; 10 is a lower belt; 12 is an airtight chamber; 14 is a bent portion; 16 is a bottom; 18 and 20 is an edge Part: 24: aqueous solution tank; 26: vinyl monomer aqueous solution; 28: mixer; 29: polymerization initiator tank; 30: vinyl monomer aqueous solution supply pipe; 31: transparent plate; 2, 34: side walls; 36: water droplets; 40: gas supply part; 42, 44: outlet; 46: Biel-based aqueous solution layer; 48a, 48b: light source; 5 0 is a wedge; 1 0 0 1 1 0 1 is a bending portion The best mode for carrying out the invention

In the present invention, the acrylamide or methacrylamide is referred to as (meth) acrylamide, and acrylic acid or methacrylic acid. Is represented as (meth) acrylic acid, and the acrylate or methacrylate is represented as (meth) acrylate.

 As the vinyl-based monomer used in the present invention, a water-soluble vinyl-based monomer is preferable.

 Specific examples of the water-soluble Biel monomer include (meth) acrylic amide; (meth) acrylic acid and alkali metal salts and ammonium salts of these acids; dimethylamino ethyl (meth) acrylate Tertiary salts such as hydrochlorides and sulfates of various dialkylamino alkyl esters of (meth) acrylic acid such as triethyl and getilamino ethyl (meth) acrylates and methyl chloride adducts of these Quaternary salts such as halogenated alkyl adducts such as halogenated alkyl adducts and benzyl chloride adducts thereof; N, N-dialkylaminoalkyl (meth) ester; acrylates and tertiary compounds thereof Examples thereof include quaternary salts, dialkyldiaryl ammonium salts, sulfoalkyl (meth) acrylates, acrylamidoalkyl sulfonic acids and salts thereof, and the like.

 Among these, acryl amide, (meth) acrylic acid and salts thereof, and tertiary salts and quaternary salts of dimethylaminoethyl (meth) acrylate are homopolymerized or co-polymerized with them. By polymerization, hydrophilic polymers such as water-soluble high-molecular-weight flocculants and water-absorbent materials can be produced. Therefore, these monomers are particularly important.

 The aqueous solution concentration of the vinyl monomer is preferably 20 to 90% by mass, and more preferably 25 to 80% by mass. If the concentration of the vinyl monomer is less than 20% by mass, the moisture content of the polymer to be obtained is high, so that the drying cost of the product becomes high, and the productivity is deteriorated. When the concentration of monomers exceeds 90% by mass, it is difficult to obtain a polymer of high molecular weight.

Even if other monomers are added to the above vinyl monomer aqueous solution Good. As other monomers, hydrophilic monomers such as dialkylaminoalkyl (meth) ester acrylate, (meth) acrylate hydroxyalkyl, polyoxyalkylene (meth) acrylate and the like can be used. Examples thereof include monomers and water-insoluble monomers such as acrylonitrile, alkyl (meth) acrylate, styrene and vinyl acetate. These other monomers are appropriately selected according to the purpose of use.

 The addition ratio of other monomers can be determined in consideration of the purpose of use, water solubility, etc. Usually, it is preferable to add 30 parts by mass or less with respect to 100 parts by mass of a water-soluble Biel based monomer.

 Furthermore, by adding a crosslinking agent as another monomer, a water-insoluble (swellable) water-absorbing polymer can be produced.

As the crosslinking agent, for example, N, N'-methylenebis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate, (poly) propylene glycol di (meth) Relate, trimethylolpropane tri (meth) acrylate, trimethylol propane di (meth) acrylate, glycerol (meth) acrylate, ethylene oxide modified Trimethylolpropane tri (meta) liquelate, pen triol ry ter eta (meth eta), octorate, dipen erysterol hexa (meth) crystal, triaryl cyanue Rate, triaryl isocyanurate, triaryl phosphate, triarylamine, poly (meth) aryloxy alkane, (poly) ethylene Glycol diglycidyl ether, glycerol diglycidyl ether, ethylene glycol, polyethylene glycol, propylene glycol, glycerin, erythylene, ethylene diamine, polyethylene amine and glycidyl (meth) acrylate Can be mentioned. Two or more of these crosslinking agents may be used. As the addition amount of these crosslinking agents, a water-soluble vinyl monomer component

The amount is preferably 0.01 to 5 parts by mass with respect to 100 parts by mass, and more preferably 0.5 to 5 parts by mass.

 In the present invention, the polymerization of the vinyl monomer is carried out by irradiating the vinyl monomer aqueous solution containing a photopolymerization initiator with light and polymerizing the polymer, and adding the redox polymerization initiator to the Biel monomer aqueous solution. And the like. The method of polymerizing by irradiating a vinyl monomer aqueous solution containing a photopolymerization initiator with light has an advantage that the degree of polymerization can be continuously adjusted and a polymer of high molecular weight can be easily obtained.

 The photopolymerization initiator for initiating the polymerization of the vinyl monomer and other monomers is not particularly limited, and a known photopolymerization initiator is appropriately selected and used according to the purpose. Specifically, azo compounds such as 2, 2-monoazobis (2-aminodipropane) salts, etc .; ketones such as 1-benzoyl-1-hydroxycyclohexene and benzozophenone and alkyl ethers thereof; Examples thereof include benzyl ketones, anthraquinone derivatives and the like.

 The addition amount of the photopolymerization initiator is preferably 10 to 100 O p p m, more preferably 10 to 3 00 0 ρ p m, with respect to the vinyl monomer. When the concentration of the photopolymerization initiator is less than 10 p p m, polymerization does not occur sufficiently, and when it exceeds 100 p p m, the degree of polymerization of the resulting polymer decreases.

The redox polymerization initiator may, for example, be a combination of the following oxidizing agent and reducing agent. Examples of the oxidizing agent include persulfates such as sodium persulfate, potassium persulfate and ammonium persulfate, organic peroxides such as t 1-peptyl peroxide peroxide and perrole SA, hydrogen peroxide, and Examples include sodium bromate and the like. Also, as a reducing agent, sulfites such as sodium sulfite, sodium hydrogen sulfite And bisulfite such as hum, ascorbic acid and its salts, rongarite, dithionite and its salts, triethanolamine, ferrous sulfate and the like.

 Preferred combinations of redox polymerization initiators include persulfates and sulfites, persulfates and bisulfites, and the like.

 The addition amount of the redox polymerization initiator may be determined in consideration of the molecular weight, the composition, and the like of the hydrophilic polymer to be obtained, but it is preferably 10 to 5 based on the total mass of the vinyl monomer to be used. 0 ppm is preferred. More preferably, it is 20 to 300 ppm.

 If necessary, a chain transfer agent, a surfactant, etc. may be added as an additive to the vinyl monomer aqueous solution.

 Chain transfer agents are used to control the molecular weight of the resulting hydrophilic polymer. Examples of chain transfer agents include thioglycolic acid, mercapto propionic acid, and salts thereof. The addition amount of the chain transfer agent is preferably 1 to 1000 ppm with respect to the vinyl monomer in the aqueous solution.

 The surfactant is added for the purpose of improving the releasability between the resulting hydrophilic polymer and the polymerization vessel or the like. The surfactant is selected from nonionic, cationic and anion based on the nature of the water-soluble monomer.

 Examples of cationic surfactants include tetraalkyl quaternary ammonium salts, trialkylbenzyl quaternary ammonium salts, alkylpyridinium salts, alkylquinolinium salts and the like.

Examples of the anionic surfactant include alkyl benzene sulfonic acid salt, alkyl naphthalene sulfonic acid salt, higher alcohol sulfuric acid ester salt, polyoxyethylene alkyl ether phosphoric acid salt and the like. Examples of nonionic surfactants include polyoxyalkylene alkyl ethers, polyoxyethylene glyceryl fatty acid esters, and polyoxyethylene fatty acid esters.

 The addition amount of the surfactant is preferably 0 to 3% by mass with respect to the aqueous Biell-based monomer solution.

 When the addition amount of surfactant is less than 0.1% by mass, the addition effect of the surfactant is not exhibited, and when it exceeds 3% by mass, the action according to the addition amount is not observed. It becomes uneconomical.

 In the method of the present invention, a method of initiating polymerization by light irradiation of the aqueous solution of Biel-based monomer is preferable. In this case, when producing a high molecular weight water-soluble polymer to be used as a coagulant, it is preferable to remove water vapor volatilized from the surface of the aqueous vinyl monomer solution in which the polymerization has been initiated. In this case, as a preferable molecular weight of the water-soluble polymer, it is preferably 5 to 200 mPa's at a salt viscosity of 0.5%. In the present invention, 0.5% salt viscosity means that a water-soluble polymer is dissolved in a 4% by mass aqueous solution of sodium chloride to prepare a water-soluble polymer solution having a concentration of 0.5% by mass. It means the value of viscosity obtained by measuring under the conditions of 25 rpm and 60 rpm using a mold viscometer.

 The preferable amount of water vapor to be removed is preferably 5 to 30%, more preferably 10 to 20%, based on the amount of water in the aqueous vinyl monomer solution.

 Among the hydrophilic polymers, the production method of the present invention is preferably applicable to the production of a water-soluble polymer.

 1 to 3 show an example of a hydrophilic polymer production apparatus used in the method for producing a hydrophilic polymer of the present invention.

In FIG. 1, the continuous belt 2 is stretched between the rollers 4 and 6. The upper belt 8 moves in the direction of arrow Q, and the lower belt 10 is approximately I'm traveling antiparallel. The continuous belt 2 is flexible, and is preferably resin-processed to improve the releasability on the surface of synthetic fiber fabric such as polyester and nylon. As the resin for resin processing, fluorine resin processing such as 4. 6 fluorinated resin, perfluoroalkoxy resin, tetrafluoroethylene resin, etc. and silicone resin are preferable.

 In the present invention, the continuous belt is formed with a bent portion 10 0 projecting downward along the traveling direction of the continuous belt. The bent portion 100 is the deepest near the portion where the vinyl monomer starts polymerization. The angle of the bending portion 100 along the traveling direction of the belt can be arbitrarily set so that the vinyl monomer aqueous solution has a desired depth, but the angle of the bending portion is 1 5 5 to 1 7 It is preferably 5 degrees, and the angle 対 with respect to the horizontal plane is preferably 0.2 to 5 degrees. It is preferable to make the bend portion 1 0 1 at the lower portion of the belt the same angle as that of the bend portion 1 00 on the upper portion of the belt so that the rotation of the belt proceeds smoothly.

 FIG. 2 is an example of a reactor used for polymerizing a vinyl monomer by light irradiation in the presence of a photopolymerization initiator. In Figure 2, the same belt as in Figure 1 is used. The polymerization part is covered in an airtight chamber. The airtight chamber preferably has an airtight chamber bend 14 as shown in FIG. 2 because the reactor is compact. In FIG. 2, 1 2 is a tunnel-shaped airtight chamber, which has an L-shaped airtight chamber fold 14 along the length direction. The continuous belt 2 passes through the inside of the airtight chamber 12.

 It is preferable that the bending angle of the airtight chamber bending portion 14 be substantially the same as the bending portion of the continuous belt.

FIG. 3 (a) is a cross-sectional view in the width direction of the airtight chamber 1 2. Airtight room The bottom 16 of 12 is formed such that the distance between the two edges 1 8 and 2 0 in the width direction increases as it goes upward. For this reason, the flexible continuous belt 2 sliding on the bottom 16 is inclined upward with the two ridges following the shape of the bottom 16. As a result, a continuous liquid reservoir is formed along the longitudinal direction on the center side, and a bent portion 100 which is the lowest at the bent portion 14 is formed.

 If the cross-sectional shape in the width direction of the belt at the bent portion 100 is concave, various shapes can be adopted. A preferable shape is one having inclined parts inclined upward at both ridges of the belt, and in particular, one having a wedge-shaped cross-section in the width direction as shown in FIG. 3 is preferable. The bent portion for reservoir 100 is a place where a vinyl monomer aqueous solution is supplied and polymerization is started here, as will be described later, and the bent portion in FIG. The solution depth of the aqueous monomer solution is the deepest. The height H of the bent portion 100 is not particularly limited, and varies depending on the production scale of the hydrophilic polymer production apparatus, the required liquid depth, and the like, and this is a design matter of a person skilled in the art. The height of the bending portion 100 is generally preferably as high as the liquid depth + 20 m. Specifically, the height H is preferably 70 to 220 mm.

 A glass plate, a transparent plastic plate, etc. are mentioned as a transparent plate which the upper surface of the airtight chamber is covered with transparent plate 31 as shown in FIG. Glass is more preferable in that it is excellent in light transmittance and heat resistance.

 The transparent plate 3 1 is mounted incliningly along the width direction of the belt 2 (downward from the side wall 32 to the side wall 3 4 in this figure). The inclination angle is preferably 0.2 to 5 degrees, more preferably 0.2 to 2 degrees. Figure 3 (a) shows an example with an inclination angle of 0.4 degrees.

If the inclination angle of the transparent plate is less than 0.2 degrees, the Biel system described later In some cases, it may not be possible to remove the condensed water vapor generated during the polymerization of the monomer sufficiently, while if it exceeds 5 °, the distance between the light source described later and the monomer aqueous solution or polymer aqueous solution becomes large. Because it is too much, sufficient light intensity may not be obtained.

 (B) in Fig. 3 shows a perspective view of the airtight chamber 1 2. In Fig. 2 (b), the description of the continuous belt is omitted.

 In Fig. 3 (b), 40 is a gas supply formed on the side wall 34, 42 is an outlet for condensed water collected in the crucible 50 formed on the side wall 34, and 4 4 is formed in the bottom 16 Condensed water outlet. Condensed water discharge port 4 4 is formed at the bent portion 14 of the bottom portion 1 6.

 In FIG. 2, reference numeral 24 denotes an aqueous solution tank disposed in front of the airtight chamber 12, in which a vinyl monomer aqueous solution 26 is accommodated. Reference numeral 2 8 denotes a mixer, which mixes the aqueous solution of the photopolymerization initiator in the polymerization initiator tank 2 9 with the aqueous solution of Biel based monomer 2 6. 3 0 is a vinyl-based monomer aqueous solution feed pipe, obtained by mixing with a mixer 2 8 'The photopolymerization initiator-containing vinyl-based monomer aqueous solution is formed on the moving direction of the continuous belt 2 improvement flow side It is supplied to the inside of the curved part 100.

 Light sources 4 8 a and 4 8 b are disposed above the airtight chamber 1 2 along the longitudinal direction of the airtight chamber. As this light source, commercially available light sources that can emit ultraviolet light and visible light, which are generally used as light sources for photopolymerization, can be used appropriately.

 Next, the case of producing a hydrophilic polymer using the above-mentioned production apparatus will be described.

First, prior to the start of polymerization, with the continuous belt stopped, the Biel monomer aqueous solution 2 6 stored inside the aqueous solution tank 24 in FIG. 2 is sent to the mixer 2 8, and the polymerization initiator tank is collected here. Mix with an aqueous solution of photoinitiator that is filled with 2 9. Then, the obtained photopolymerization start The agent-containing vinyl monomer aqueous solution is fed through the feed pipe 30 into the bend portion 100 formed on the upstream side in the moving direction of the continuous belt 2. As a result, the pinyl monomer aqueous solution layer in the bending portion 100 on the belt 2

4 6 are formed. At this time, the supply amount of the photopolymerization initiator-containing vinyl monomer aqueous solution is as follows: bending portion 10 of the vinyl monomer aqueous solution layer 4 6

Adjust the liquid depth at 0 to the desired depth. In the method of the present invention, the preferred solution depth is 50 m or more, more preferably

It is 5 5-2 0 O m m.

 Thereafter, the vinyl monomer aqueous solution layer 4 6 formed on the continuous belt 2 is irradiated with light using a light source 4 8 a.

 By the light irradiation, the polymerization of the monomers in the vinyl monomer aqueous solution layer 4 6 formed in the bending portion 100 of the belt 2 is started, and the heat of polymerization starts to be generated accordingly. As a result, the temperature of the vinyl monomer aqueous solution layer 4 6 begins to rise.

 As the polymerization proceeds, water starts to volatilize from the surface of the Biel based monomer aqueous solution layer 4 6. The volatilized water immediately travels through the air-tight chamber 12 along with the inert gas flowing in the direction perpendicular to the direction of movement of the belt 2 along the surface of the Biel-based monomer aqueous solution layer 46 and moves in the air-tight chamber 12. It is discharged to the outside from the discharge port (not shown) formed on the opposite side to the gas supply unit 18.

 Further, as shown in FIG. 3, the generated water vapor is cooled by a transparent plate 31 that covers the upper part of the hermetic chamber to form water droplets 36. In this case, the transparent plate 3 1 can condense water vapor only by cooling with the outside air without using a cooling device or the like.

The water droplets 3 6 travel along the slope of the transparent plate 3 1 along the lower surface of the transparent plate 3 1, move to the side wall 3 4 side, and fall into the crucible 50 formed along the side wall 3 4. Is discharged from the discharge port 42 to the outside. In addition, A portion of the reduced water is also discharged to the outside from the discharge port 44 through the lower surface of the belt 2.

 In the case of a method of reducing the oxygen concentration by supplying an inert gas from the upper portion of the belt inlet as in the conventional airtight chamber, the surface of the aqueous monomer solution is cooled and the generation of water vapor is suppressed. The physical properties of the resulting polymer may be low. On the other hand, there is no such a problem when removing water vapor by supplying an inert gas along the width direction of the continuous belt 2 as in the present embodiment.

As the inert gas supply condition, 0.5 to 40 m ³ Z hr is preferable. In addition, it is preferable to connect the exhaust to an exhaust system (not shown). By linking in this way, water vapor can be removed efficiently.

 As a result, the vinyl monomer aqueous solution layer 46 that has started the polymerization is forced to exclude water near the surface, and is concentrated, so that the monomer concentration near the surface is separated from the surface. It is considered to be higher than the part. That is, the vinyl-based monomer concentration in the Biel-based monomer aqueous solution layer 46 in which the polymerization has been initiated becomes successively higher as it goes to the surface of the aqueous solution layer 46.

 As a result, it is considered that the degree of polymerization of the polymer formed in the vicinity of the surface of the Biel based monomer aqueous solution layer 4 6 is kept high.

Next, when the vinyl monomer aqueous solution layer 46 on the continuous belt 2 is cured, the photopolymerization initiator-containing vinyl monomer aqueous solution is continued to the bent portion on the belt 2 through the supply pipe 30. Continuously move the belt 2 in the Q direction while feeding as desired. In this case, since the cured vinyl monomer aqueous solution layer is present in the belt moving direction to play a role of wrinkles, the photopolymerization initiator-containing vinyl monomer aqueous solution can flow in the belt moving direction. The fluid depth is kept at a predetermined depth. In this way, the vinyl monomer monomer aqueous solution containing the photopolymerization initiator is continuously supplied to the belt 2 and the light source 48a irradiates the light continuously to carry out the polymerization continuously. The resulting polymer is sent in the direction of belt 2 travel. Further, light is irradiated with a light source 48 b to complete the polymerization, and then the mixture is discharged from the hermetic chamber 12 through the most downstream part of the hermetic chamber 12. Further, the polymer is peeled off the continuous belt 2 in the vicinity of the roller 6. The polymer thus produced is cut, pulverized and dried according to a conventional method to obtain a powdery hydrophilic resin product.

 The production method of the present invention can be preferably applied to the production method of a water-soluble polymer for flocculant which is likely to largely inhibit the polymerization due to the presence of oxygen. Example

 Hereinafter, the present invention will be more specifically described by way of examples.

 Example 1

 (Manufacture of polymer flocculant)

 The water-soluble vinyl monomer was polymerized using the apparatus shown in FIG. In addition, the angle 撓 of the bending portion 100 of the continuous belt upper surface is 160 degrees at an angle に 対 す る of 200 degrees with respect to the horizontal plane, and the bending angle of the bending portion 14 of the airtight chamber is 160 degrees similarly. The length from the bent part 14 to the lowermost part of the airtight chamber was 3 m, and the inclination angle of this part was 2.5 degrees. Continuous belt 2 was obtained by laminating a fluorine resin on the belt surface knitted with polyester resin.

Distilled water is added to a monomer mixture of 90 mol% of acrylamide and 10 mol% of a methyl chloride adduct of dimethyl aminoethyl acrylate (hereinafter referred to as "DACJ"), and the monomer concentration is 32 mass%. There were obtained 800 g of a monomer aqueous solution of After adjusting pH to 4.0, warm Bubbling with nitrogen for 30 minutes while maintaining the temperature at 10 ° C. The solution was charged into the aqueous solution tank 4.

 Separately, based on the monomer mass of this aqueous monomer solution, an aqueous solution in which the photopolymerization initiator (azobisamidinopropane hydrochloride) becomes 180 ppm is prepared, and this is subjected to nitrogen for 2 minutes. After bubbling, it was charged into a polymerization initiator tank 2 9.

 Furthermore, in order to make the airtight chamber into a nitrogen atmosphere, nitrogen substitution in the airtight chamber was started 1 hour before the supply of the aqueous monomer solution was started.

 With the belt 2 stopped, the aqueous monomer solution and the aqueous solution of the photopolymerization initiator are mixed by the mixer 28 and the resultant aqueous solution containing the photopolymerization initiator-containing vinyl monomer is fed through the supply pipe 30 to the belt It was supplied to the flexible portion 1 0 0 formed on 2. The supply of the photopolymerization initiator-containing vinyl monomer aqueous solution was stopped when the liquid depth of the deepest portion (flexure portion) of the photopolymerization initiator-containing vinyl monomer aqueous solution reached 70 mm. At this time, the liquid tip of the aqueous solution of the photopolymerization initiator-containing Biel-based monomer was 1.6 m downstream of the bent portion 1000.

Next, ultraviolet light was irradiated for 20 minutes from the upstream end of the hermetic chamber 12 to 1.5 m downstream using a light source 4 8 a. A 10 W chemical lamp (trade name “FL 10 BL” manufactured by Toshiba Corporation) was used as a light source 4 8 a. The irradiation intensity was 5 WZ m ² . By irradiation with ultraviolet light, the photopolymerization initiator-containing vinyl monomer aqueous solution initiated polymerization while generating heat. The water vapor generated from the surface was condensed on the glass plate disposed above, and flowed down along the slope of the glass plate while forming water droplets. The water droplets were collected in a crucible 50 and discharged from the outlet 42 to the outside. Thereby, the monomer was completely polymerized and gelled.

After complete gelation, the drive of the continuous belt 2 was started, and the continuous supply of the photopolymerization initiator-containing vinyl monomer aqueous solution was started. In addition, a black light (manufactured by Toshiba Corporation, trade name FL 400 BL) is disposed as a light source 48 b at a later stage of the light source 48 a (chemical lamp), and 400 W Ultraviolet rays were irradiated at an irradiation intensity of / m ² . At the downstream of the airtight chamber 12, the gelled water-soluble polymer was continuously peeled off from the continuous belt 2. The thickness was the same as the deepest portion 70 mm deep. The manufacturing method of the present embodiment does not require any manual work such as removing a weir during operation, the operability is improved, and continuous stacking can be started in a short time. In addition, the supplied photoinitiator-containing vinyl monomer aqueous solution was completely polymerized on the belt without leaking out of the continuous belt. Therefore, all the raw materials could be used without loss. Furthermore, since there is no aqueous monomer solution leaking out of the belt, the continuous operation can be continued without contaminating the belt roller and the inside of the airtight chamber. It was cut into pieces of about 6 mm and then dried at 80 ° C. for 5 hours using a hot air drier. Thereafter, it was pulverized by a pulverizer to obtain a powdery polymer flocculant. The obtained flocculant had a high molecular weight and a small amount of insoluble matter. Further, it was 10 mm, 10 to 30 mm, 30 to 50 mm, and 50 to 70 from the polymer surface. Example 2 where the 0.5% salt viscosity at 80 mm sampling position was 80, 82, 81 and 83] 11-3 '3 respectively

 (Production of water-absorbent resin)

The water-soluble vinyl monomer was polymerized using the apparatus shown in FIG. The angle α of the bending portion 100 of the continuous belt is 160 ° and the angle に 対 す る to the water plane is 2.5 °. Similarly, the bending angle of the bending portion 14 of the airtight chamber is 1 6 0 The length from the bending part 14 to the most downstream of the airtight chamber was 3 m, and the inclination angle of this part was 2.5 degrees. Continuous belt 2 is silicon cone on the belt surface woven with polyester resin The resin was applied and impregnated.

 To a mixture of monomers of 25 mol% acrylic acid and 75 mol% sodium acrylate, trimethylolpropane triacrylate as a crosslinker 300 ppm (relative to the total mass of the monomers) Distilled water was added to the mixture to which was added so that the total mass was 800 g, and the monomer concentration was 40% by mass, to obtain an aqueous monomer solution. The temperature of the monomer aqueous solution was maintained at 20 ° C., followed by publication with nitrogen for 10 minutes. This was charged into the aqueous solution tank 2 4.

 On the other hand, an aqueous solution of 0.5 ppm of a photopolymerization initiator (2,2-dimethoxy-1,2-diphenylethane-1-one) was prepared based on the monomer mass in the aqueous monomer solution. . It was charged with nitrogen for 2 minutes and then charged into a polymerization initiator tank 29.

 Furthermore, in order to make the airtight chamber into a nitrogen atmosphere, nitrogen substitution was carried out 1 hour before the start of the supply of the aqueous monomer solution.

 While the belt 2 is stopped, the monomer aqueous solution and the photopolymerization initiator water solution are mixed by the mixer 28 and the photopolymerization is performed at the bent portion 10 0 formed on the belt 2 through the supply pipe 30. An initiator-containing vinyl monomer aqueous solution was supplied. The supply of the aqueous monomer solution was stopped when the liquid depth of the deepest portion (flexible portion) of the aqueous solution of the vinyl monomer monomer containing the photopolymerization initiator reached 55 mm. At this time, the liquid tip of the monomer aqueous solution was located 1.3 m downstream from the bending portion 1000.

Then, the ultraviolet ray was irradiated for 30 seconds from the upper side of the airtight chamber 12 using a high-pressure mercury lamp (4 kW, 80 w / cm, emission length 500 mm) as a light source 48a ( quantity ^{7 5 0 m J / cm 2} ). The UV radiation part was a section of 0.5 m from the upstream tip of the airtight chamber 12 to the downstream side. By irradiation with ultraviolet light, the photopolymerization initiator-containing vinyl monomer aqueous solution initiated polymerization while generating heat. surface The water vapor generated was condensed on the glass plate disposed above, and flowed down along the slope of the glass plate while forming water droplets.樋 This water drop

It was collected at 50 and discharged to the outside from discharge port 42. By this, the monomer completely polymerized and gelled.

 After complete gelation, the driving of the continuous belt 2 was started, and the continuous supply of the photopolymerization initiator-containing vinyl monomer aqueous solution was started.

 The gelled hydrophilic polymer was continuously peeled off from the continuous belt 2 near the downstream side of the airtight chamber. The thickness was kept the same as the deepest liquid depth of 55 mm.

 In this example, since there was no manual operation such as removing the crucible during the operation, the operability was improved, and the continuous polymerization could be started in a short time. In addition, since there was no manual work, the exposure of the skin etc. to the highly irritating acrylic acid vapor was eliminated, and safety was improved. In addition, since the supplied aqueous solution of the photopolymerization initiator-containing vinyl monomer never leaks out of the continuous belt, the entire amount is polymerized on the belt and the raw material can be used without loss. Furthermore, since the aqueous monomer solution did not leak out of the belt, continuous operation could be continued without contaminating the belt roller 1 and the inside of the airtight chamber.

 The obtained hydrophilic polymer was shredded into a mass having a particle diameter of about 3 m using a meat cutter, and then dried using a hot air drier at 135 ° C. for 1 hour. The dried hydrophilic polymer was pulverized with a roll mill crusher, and a water-absorbent resin having a particle diameter of 300 0 m to 500 m was selected. To this, the resin surface was crosslinked by spraying an aqueous solution of ethylene glycol diglycidyl ether under heating. The obtained polymer particles had a high water absorption and a small amount of residual monomers.

 Comparative example 1

As a continuous belt, as shown in FIG. A linear airtight chamber which does not have 0 and uses a linear belt which is inclined by 3 = 2.5 ° as a whole in the downward direction of the belt advancing direction and whose airtight chamber does not have an airtight chamber bending portion A reactor of the same configuration as shown in Figure 2 and Figure 3 was used except that it was equipped. On the continuous belt, the temporary tacking wedge 15 was placed at a position of 1.5 m from the tip. An aqueous monomer solution is prepared in the same manner as in Example 1, and the air-tight chamber is purged with nitrogen for 1 hour, and then the aqueous solution containing the photopolymerization initiator containing vinyl monomer is passed through a supply pipe 30 to a depth of 70 mm. Filled in the pot so as to become.

 In the same manner as in Example 1, ultraviolet light was irradiated by a light source 4 8 a to initiate polymerization and complete gelation.

 One hour after the start of polymerization, the nitrogen in the airtight chamber was purged with air. After confirming that the oxygen concentration in the airtight chamber became the same as that of air, manually remove the temporary closure rod, and then inside the airtight chamber again. Nitrogen substitution was performed for 1 hour in order to set it under a nitrogen atmosphere.

 After the completion of the nitrogen substitution, while the aqueous solution of the photopolymerization initiator-containing Biel type monomer was again supplied to the belt, ultraviolet light was irradiated from the light source 4 8 a in the same manner as described above to start driving of the continuous belt. Thus, continuous polymerization was started in the same manner as in Example 1.

 In contrast to Example 1, in Comparative Example 1, an additional 3 hours in total was required until the continuous polymerization was resumed.

 Comparative example 2

 The manufacturing apparatus used in Comparative Example 1 was used. On the continuous belt, a tacking weir 15 was placed at a position of 1.3 m from the tip. A monomer aqueous solution is prepared in the same manner as in Example 2, and the air-tight chamber is purged with nitrogen for 1 hour, and then the aqueous solution containing the photopolymerization initiator-containing vinyl monomer is passed through a supply pipe 30. Filled in the bag so that it would be mm.

In the same manner as in Example 2, ultraviolet light was irradiated to the aqueous solution by a light source 4 8 a. The polymerization was initiated to complete gelation.

 One hour after the start of the polymerization, the nitrogen in the airtight chamber was purged with air to make the chamber air composition, and the gel temperature was lowered, and the gel had no vapor with an acrylic acid odor. confirmed. The temporary fixing crucible was removed by manual work, and nitrogen replacement was performed for one hour in order to make the airtight chamber have a nitrogen atmosphere again.

 After the completion of the nitrogen substitution, while the photopolymerization initiator-containing vinyl monomer aqueous solution was again supplied onto the belt, the ultraviolet light was irradiated from the light source 4 8 a to start polymerization, and drive of the continuous belt was started. Thus, continuous polymerization was initiated in the same manner as in Example 2.

 In this Comparative Example 2, a total of 3 hours more than in Example 2 was required to resume the continuous polymerization.

Claims

The scope of the claims  1. In a method for producing a hydrophilic polymer in which an aqueous solution of a vinyl monomer is continuously supplied to the upper surface of a movable belt to polymerize the monomer, the continuous belt includes the vicinity of a polymerization portion of a Biel monomer. Forming a bending portion projecting downward at the deepest position along the traveling direction of the continuous belt, and initiating polymerization of a vinyl-based monomer at the bending portion. Production method.  2. The method for producing a hydrophilic polymer according to claim 1, wherein an inclined portion which is inclined upward is formed at both edges of the continuous belt.  3. The method for producing a hydrophilic polymer according to claim 1, wherein a bend is provided such that the solution depth of the vinyl monomer aqueous solution in the bend is 50 m or more.  4. The method for producing a hydrophilic polymer according to claim 1, wherein the polymerization of the vinyl-based monomer is performed by irradiating a vinyl-based monomer aqueous solution containing a photopolymerization initiator with light.  5. The hydrophilic polymer according to claim 1, wherein the obtained hydrophilic polymer is a water-soluble polymer, and water vapor volatilized from the surface of the vinyl monomer aqueous solution which has been polymerized is eliminated. Manufacturing method of union.