JPH11228609A - Production of water-soluble polymer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing a water-soluble polymer improved in productivity and quality, compared with conventional methods. SOLUTION: This method for producing a water-soluble polymer comprises putting an aqueous solution 5 of a water-soluble monomer containing photopolymerization initiator into a vessel 1 <=50 mm in depth, covering the surface of the aqueous solution 5 with a light transmittable film 6, irradiating with visible light or ultraviolet light from the upper side of the light transmittable film 6 and polymerizing the water-soluble monomer; wherein the bottom of the vessel 1 is cooled through a water-cooling or air-cooling method, and simultaneously the upper side of the light transmittable film 6 is cooled through an air-cooling method.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for producing a water-soluble polymer by photopolymerization.

[0002]

2. Description of the Related Art Cationic, nonionic, and anionic water-soluble polymers are widely used in applications such as flocculants for treating sewage and wastewater, chemicals for papermaking, and chemicals for oil recovery. Occupy position. As a method for producing these water-soluble polymers, various methods such as an aqueous solution polymerization method, an emulsion polymerization method, a suspension polymerization method, and a precipitation polymerization method are used, and among them, the aqueous solution polymerization method is most commonly used. I have.

As one example of an industrial production method using aqueous solution polymerization, a water-soluble monomer aqueous solution containing a photopolymerization initiator is poured into a flat container having a shallow bottom, and the surface of the water-soluble monomer aqueous solution is washed. Nitrogen gas, sealed with a light-transmitting film, etc., irradiating visible light or ultraviolet light from the upper surface, polymerizing the water-soluble monomer to produce a sheet-shaped water-soluble polymer,
JP-B-55-12445, JP-B-3-26205
JP, JP-B3-65821, JP-B6-80
No. 4 discloses this.

However, in the above-mentioned production method, since only the bottom of the container is cooled to remove the generated heat of polymerization, the ability to remove the generated heat of polymerization is naturally limited. Therefore, when producing a water-soluble polymer having a relatively high molecular weight, it is necessary to take measures such as lowering the concentration of the water-soluble monomer and lowering the polymerization rate so that the polymerization system does not reach a high temperature. Did not. For this reason, there are problems such as a decrease in productivity such as time required for production and drying of the water-soluble polymer, and quality problems such as an increase in unreacted water-soluble monomers remaining in the water-soluble polymer. I was In particular, when a water-soluble monomer having a small molecular weight such as acrylamide or acrylic acid is used, these problems appear remarkably.

In addition, since only the bottom of the container is cooled, a temperature difference occurs between the bottom and the top of the container, causing uneven polymerization. As a result, there is also a quality problem that the molecular weight of the produced water-soluble polymer becomes uneven.

[0006]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a method for producing a water-soluble polymer having improved quality compared to the conventional one with high productivity.

[0007]

An object of the present invention is to provide a water-soluble monomer aqueous solution containing a photopolymerization initiator, which is poured into a container having a depth of 50 mm or less. Cover with a film, irradiate visible light or ultraviolet light from the upper surface of the light-transmitting film, in the method of producing a water-soluble polymer to polymerize the water-soluble monomer, when the bottom of the container is cooled by a water-cooling method or an air-cooling method At the same time, the problem is solved by using a method of cooling the upper surface of the light transmitting film by an air cooling method.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for producing a water-soluble polymer of the present invention will be described in detail. First, an aqueous solution of a water-soluble monomer as a raw material is prepared, and a photopolymerization initiator and, if necessary, an additive are added to the aqueous solution of the water-soluble monomer. An inert gas such as nitrogen gas is blown into the aqueous solution of the water-soluble monomer containing the photopolymerization initiator to expel oxygen, and the depth is 50 mm.
Pour into the following container and cover the surface of the aqueous solution of the water-soluble monomer with a light-transmitting film. Then, at the same time as cooling the bottom of the container with a water-cooling method or air-cooling method, while irradiating visible light or ultraviolet light from the upper surface of the light-transmitting film while cooling the upper surface of the light-transmitting film with the air cooling method, the water-soluble monomer is cooled. A water-soluble polymer is obtained by polymerization.

The water-soluble monomer used in the present invention includes, for example, a water-soluble cationic monomer, a water-soluble nonionic monomer, and a water-soluble anionic monomer.
These can be used alone or in combination of two or more as necessary.

Examples of the water-soluble cationic monomer include tertiary amine salts and quaternary ammonium salts. Examples of the salt of a tertiary amine include dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, and 3-dimethylamino-
Salts obtained by neutralizing a tertiary amine such as 2-hydroxypropyl (meth) acrylate or dimethylaminopropyl (meth) acrylate with an acid such as hydrochloric acid or sulfuric acid are exemplified. Specifically, sulfate of dimethylaminoethyl methacrylate (DMZ) or the like is used.

As the quaternary ammonium salt, for example,
Examples thereof include dimethyldiallylammonium salt and diethyldiallylammonium salt. Also, a salt obtained by quaternizing the above tertiary amine with an alkyl halide such as methyl chloride, methyl bromide, or methyl iodide, or dimethyl sulfate is used. You can also. In particular,
Dimethylaminoethyl methacrylate methyl chloride quaternary salt (DMC), dimethylaminoethyl acrylate methyl chloride quaternary salt (DME), dimethylaminoethyl methacrylate benzyl chloride quaternary salt (DML), dimethylaminopropyl acrylamide methyl chloride 4 Grade salt (DPAC) or the like is used. These can be used alone or in combination of two or more as necessary.

Examples of the water-soluble nonionic monomers include acrylamide (AAm) and methacrylamide (MAAm). These can be used alone or in combination of two or more as necessary.

The water-soluble anionic monomers include, for example, acrylic acid (AA), methacrylic acid (MAA),
2-acrylamido-2-methyl-propiosulfonic acid (AMPS) and the like. These can be used alone or in combination of two or more as necessary.

The concentration of these water-soluble monomers is not particularly limited as long as the uniformity of the polymerization system can be maintained, but the concentration is increased in consideration of production cost. Is preferred. This is because when the concentration of the water-soluble monomer is low, the drying cost increases, and the production of the water-soluble polymer requires a long time. On the other hand, if the concentration of the water-soluble monomer is too high, it becomes difficult to obtain a high-molecular-weight water-soluble polymer. Therefore, it is preferable that the concentration of the water-soluble monomer in the aqueous solution is determined experimentally in consideration of physical properties and production conditions required for the water-soluble polymer.

The photopolymerization initiator used in the present invention may be a generally known photopolymerization initiator, and typical examples thereof include benzoin, benzoin alkyl ether, anthraquinone derivative, 2-hydroxy-2-methyl -1-phenylpropan-1-one and the like. The amount of the photopolymerization initiator is preferably in the range of 10 to 2000 ppm based on the aqueous solution of the water-soluble monomer. When the amount of the photopolymerization initiator is 10 ppm or less, the effect as a photopolymerization initiator is insufficient, and when the amount exceeds 2000 ppm, a high molecular weight water-soluble polymer is difficult to obtain, which is not preferable.

The additives include, for example, a chain transfer agent and a surfactant. The chain transfer agent,
In order to adjust the degree of polymerization of the obtained water-soluble polymer, it is added in the range of 2 to 2000 ppm with respect to the aqueous solution of the water-soluble monomer. Examples of the chain transfer agent include, for example, when polymerizing under acidic or neutral conditions, thioglycolic acid, mercaptopropionic acid, phosphorous acid, hypophosphorous acid, etc., and under neutral or alkaline conditions. In this case, these sodium salts and the like can be mentioned.

The above surfactant is added to improve the releasability of the obtained water-soluble polymer from a container or a film. When the water-soluble polymer is cationic or amphoteric, a cationic or nonionic surfactant is used. When the water-soluble polymer is an anionic or nonionic surfactant, an anionic or nonionic surfactant is used.

Examples of the above-mentioned cationic surfactant include tetraalkyl quaternary ammonium salts, trialkylbenzyl quaternary ammonium salts, alkylpyridinium salts, and alkylquinolinium salts. Examples of the anionic surfactant include, for example, alkyl benzene sulfonate, alkali naphthalene sulfonate,
Higher alcohol sulfates and polyoxyethylene alkyl ether phosphates are exemplified. Examples of the nonionic surfactant include polyoxyethylene alkyl ether, polyoxyethylene glycerin fatty acid ester, and polyethylene glycol fatty acid ester.

The amount of the surfactant to be added is not particularly limited.
It is in the range of 1-2% by weight. If the amount is less than 0.01% by weight, the effect is insufficient, and if it exceeds 2% by weight, no increase in effect is observed, which is not preferable in terms of cost.

The container used in the present invention is not particularly limited. For example, a box-shaped container opened upward,
Containers usually used for the production of a water-soluble polymer, such as a continuous production apparatus in which weirs are provided on both sides of an endless belt, may be mentioned. Further, the depth of the container is preferably set to 50 mm or less. If the depth of the container exceeds 50 mm, it is difficult to remove the heat of polymerization, and there is a difference in the amount of visible light or ultraviolet light incident on the top and bottom of the container.

Usually, a film or the like is laid on the bottom surface of the container in order to improve the releasability of the produced water-soluble polymer from the container. Such a film is preferably non-adhesive to a water-soluble polymer and has good light transmittance in order to efficiently polymerize using reflected light from the bottom surface in the container. Examples of such a film include films of polyethylene terephthalate (hereinafter referred to as PET), nylon, polypropylene and the like. Furthermore, from the viewpoint of heat resistance and strength,
A 50 μm PET film is particularly preferred.

In the present invention, the light-transmitting film covering the surface of the water-soluble monomer is preferably a film having low oxygen permeability and heat resistance. Films coated with polyvinylidene chloride or the like having low properties are exemplified. The thickness of the film is set according to the type of the water-soluble monomer to be used, the material of the film, and the like, and is not particularly limited. For example, in the case of a PET film coated with polyvinylidene chloride, usually, 5 ２５25 μm. When the thickness is 5 μm or less, the strength is insufficient, and when the thickness is 25 μm or more, the strength is excessive and the cost increases, which is not preferable.

As the method of cooling the bottom of the container used in the present invention, for example, a method of spraying water using a nozzle from the lower part of the container to cool it, or a method of cooling by flowing water so as to contact the bottom of the container. Method, a method of cooling by blowing air using a nozzle from the bottom direction of the container,
A cooling method using a blower fan may be used.

Examples of the method for cooling the upper surface of the light-transmitting film include a method of cooling by blowing air from a nozzle, a method of cooling using a blower fan, and the like. Above all, a method of cooling by blowing air from a nozzle is preferable because the area for blocking visible light or ultraviolet light irradiated from the upper surface of the light transmitting film is small.

The visible light or ultraviolet light used in the present invention is selected depending on the combination with a photopolymerization initiator. Those having a wavelength of 500 nm are preferred. As the light source, for example, a high-pressure mercury lamp,
Ultra-high pressure mercury lamps, fluorescent chemical lamps, and the like are included.

In such a method for producing a water-soluble resin, the cooling efficiency is improved by cooling the bottom of the container with a water cooling system or an air cooling system and simultaneously cooling the upper surface of the light transmitting film by an air cooling system. So you can
The polymerization rate and the concentration of the water-soluble monomer can be increased as compared with the conventional method. Therefore, the production time and drying time of the water-soluble polymer are shortened, unreacted water-soluble monomers remaining in the water-soluble polymer are reduced, and a high-molecular-weight water-soluble polymer is obtained. In addition, since the temperature difference between the top and bottom of the vessel during polymerization is small, it is possible to obtain a water-soluble polymer having less unevenness in molecular weight.

[0027]

The present invention will be described in more detail with reference to the following examples. Here, “%” indicates “% by weight”. The physical properties of the obtained water-soluble polymer were measured using the following methods. 0.5% solution viscosity in salt water (0.5% ηs) A 0.5% aqueous solution of a water-soluble polymer dry powder was adjusted to 500 ml, and 5.85 g of sodium chloride was added and dissolved therein. Rotor speed 6 r. p. The viscosity of the solution was measured in m. -Residual acrylamide (RAAm) 3 g of a dry powder of the water-soluble polymer was extracted by shaking with 30 ml of an extraction solvent for 24 hours, and a column of Chromosolve 101 (3 mmφ) was used.
× 1 m), acrylamide (AAm) was quantified by gas chromatography at 170 ° C., and the result was shown as a percentage by weight of residual acrylamide in the dry powder. As the extraction solvent, a mixed solution of methanol / water = 80/20 as a volume ratio was used.

Example 1 Methyl chloride quaternary salt of dimethylaminoethyl acrylate having a concentration of 80% (hereinafter referred to as D)
500 g of an aqueous solution of acrylamide (hereinafter referred to as AAm) having a concentration of 50%,
60 g were prepared. In these solutions, 100 ppm of 2-hydroxy-2-methyl-1-phenylpropan-1-one as a photopolymerization initiator, 50 ppm of disodium ethylenediaminetetraacetate as an additive, and 155 ppm of phosphorous acid as a chain transfer agent were added. So as to be added, and further, as a cationic surfactant, Sanisol B
-50 (manufactured by Kao Corporation) was added to each solution to a concentration of 0.1%. The temperature of these solutions was adjusted to 17 ° C., the pH was adjusted to 4.5 ± 0.1 with 20% sulfuric acid with stirring, and nitrogen gas was blown at 6 l / min for 30 minutes.

Next, these solutions were poured into a container 1 as shown in FIG. In this container 1, a weir 3 is made of a trapezoidal rubber rod having a cross section of 40 mm on the upper side, 45 mm on the lower side, and 20 mm in height so that the bottom surface is 23 cm × 23 cm. 4 is laid. In addition, the prepared solution is
The concentration of the water-soluble monomer aqueous solution 5 when the mixture was poured into the mixture was 40%. The surface of the water-soluble monomer aqueous solution 5 poured into the container 1 is coated with a 16 μm-thick light transmissive film 6 (PET film 12) made by coating polyvinylidene chloride on a PET film.
μm + polyvinylidene chloride 4 μm) to cover the PET layer so as to be in contact with the aqueous monomer solution 5, and to remove nitrogen gas bubbles remaining between the aqueous monomer solution 5 and the light transmitting film 6.

Next, from the upper surface of the light transmitting film 6, the surface temperature of the water-soluble monomer aqueous solution 5 is increased by 5 ° C. using a fluorescent chemical lamp 7 manufactured by Mitsubishi Electric Corporation (Ip).
Up to 2.0 W / m ² of UV light (1st
Irradiation), after Ip, irradiation was performed at an illuminance of 0.6 W / m ^{2 up to} the peak temperature (Tp), and after Tp was indicated (Δp),
Irradiation was continued for another 20 minutes (2nd irradiation).

During irradiation with ultraviolet light, 17
C. water was sprayed at 2 l / min from the fountain nozzle 8 to cool the bottom of the container 1. After 5 minutes from Ip, the air nozzle 9 provided between the light transmitting film 6 and the fluorescent chemical lamp 7 starts blowing air at a wind speed of 5 m / sec onto the upper surface of the light transmitting film 6. Then, the upper surface of the light transmitting film 6 was cooled.

The obtained water-soluble polymer was 5 mm × 5 mm ×
Cut to a size of about 50 mm, and dry in a dryer at 60 ° C.
Let dry for hours. After drying, it was cooled to room temperature and pulverized with a Willet pulverizer to obtain a dry powder sample. The 0.5% solution viscosity (0.5% ηs) and residual acrylamide (RAAm) of this sample were measured in salt water. Table 1 shows the results.

[0033]

[Table 1]

Comparative Example 1 A water-soluble polymer was produced in the same manner as in Example 1 except that the upper surface of the light transmitting film 6 was not cooled, and a dry powder sample was obtained. 0.5 of salt water of this sample
% Solution viscosity (0.5% ηs) and residual acrylamide (RAAm) were measured. Table 1 shows the results.

Example 2, Comparative Example 2 A water-soluble polymer was produced in the same manner as in Example 1 and Comparative Example 1. The obtained water-soluble polymer was sampled every 0.5 cm in the thickness direction, and 0.5 cm to 1.0 c from the surface to 0.5 cm.
Each sample from m, 1.0 cm to 1.5 cm, 1.5 cm to the bottom was dried and pulverized in the same manner as in Example 1 to obtain a dry powder sample. 0.5% solution viscosity (0.5% ηs) and residual acrylamide (RAA)
m) was measured. Table 2 shows the results.

[0036]

[Table 2]

Examples 3 to 5 Example 1 was repeated except that the concentration of the water-soluble monomer aqueous solution in Example 1 was changed as shown in Table 3 without changing the composition ratio of DME and AAm. A water-soluble polymer was produced in the same manner as described above to obtain a dry powder. The 0.5% solution viscosity (0.5% ηs) and residual acrylamide (RAAm) of this sample were measured in salt water.

[0038]

[Table 3]

(Comparative Examples 3 to 5) Comparative Example 1 was repeated except that the concentration of the water-soluble monomer aqueous solution in Comparative Example 1 was changed as shown in Table 3 without changing the composition ratio of DME and AAm. A water-soluble polymer was produced in the same manner as described above to obtain a dry powder. The 0.5% solution viscosity (0.5% ηs) and residual acrylamide (RAAm) of this sample were measured in salt water. Table 3 shows the results. However, when the aqueous solution of the water-soluble polymer boiled during the production, the measurement was not performed.

(Examples 6 to 27) As shown in Table 4, the composition of the water-soluble monomer, the concentration, the amount of the photopolymerization initiator, the pH of the aqueous solution of the water-soluble monomer, and the UV irradiation conditions were changed. When the water-soluble polymer was an anionic or nonionic polymer, a water-soluble polymer was used in the same manner as in Example 1 except that NE560H (manufactured by Nippon Emulsifier Co., Ltd.) was used instead of Sanizol B-50 as a surfactant. Was obtained to obtain a dry powder sample. Solution viscosity and residual acrylamide (RAA)
m) was measured. Table 4 shows the results.

[0041]

[Table 4]

(Comparative Examples 6 to 27) As shown in Table 5, the water-soluble monomer composition, the concentration, the amount of the photopolymerization initiator, the pH of the water-soluble monomer aqueous solution, and the UV irradiation conditions were changed. When the water-soluble polymer was an anionic or nonionic polymer, a water-soluble polymer was used in the same manner as in Comparative Example 1 except that NE560H (manufactured by Nippon Emulsifier Co., Ltd.) was used instead of Sanizol B-50 as a surfactant. Was obtained to obtain a dry powder sample. Solution viscosity and residual acrylamide (RAA)
m) was measured. Table 5 shows the results.

[0043]

[Table 5]

From these results, by using the method for producing a water-soluble polymer of the present invention, a water-soluble monomer having a high molecular weight, a small amount of remaining water-soluble monomer, and a small unevenness in the molecular weight can be obtained. You can see that. In addition, it can be seen that the concentration of the water-soluble monomer can be increased, and the polymerization time is shortened.

[0045]

As described above, in the method for producing a water-soluble polymer of the present invention, the bottom of the container is cooled by a water-cooling method or an air-cooling method, and at the same time, the upper surface of the light-transmitting film is cooled by an air-cooling method. By cooling, the cooling efficiency is dramatically improved, so that an excellent effect of improving the productivity and quality of the water-soluble polymer can be obtained.

[Brief description of the drawings]

FIG. 1 is a schematic sectional view showing an example of a manufacturing apparatus used in an embodiment of the present invention.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Container, 5 ... Water-soluble monomer aqueous solution, 6 ... Light transmissive film, 7 ... Fluorescent chemical lamp, 8 ... Fountain nozzle, 9 ... Air nozzle

Claims (1)

[Claims] 1. A water-soluble monomer aqueous solution containing a photopolymerization initiator is poured into a container having a depth of 50 mm or less, and the surface of the monomer aqueous solution is covered with a light-transmitting film. A method for producing a water-soluble polymer, which comprises irradiating more visible light or ultraviolet light and polymerizing the water-soluble monomer, wherein the bottom of the container is cooled by a water-cooling method or an air-cooling method. A method for producing a water-soluble polymer, wherein the upper surface is cooled by air cooling.