JPH0125761B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing porous crosslinked polyvinyl alcohol by reacting a crosslinking agent with polyvinyl alcohol. It is known to produce water-insoluble crosslinked polyvinyl alcohol by reacting polyvinyl alcohol with a crosslinking agent. However, the crosslinked polyvinyl alcohol obtained in this way is in the form of a gel. A method for producing porous crosslinked polyvinyl alcohol is to copolymerize vinyl acetate and a crosslinking agent,
A method has been proposed in which the product is hydrolyzed and then cross-linked again with epichlorohydrin (Japanese Patent Application Laid-Open No. 138077/1983). According to the present invention, the linear polyvinyl alcohol and the crosslinking agent are reacted in water in which the linear polyvinyl alcohol is dissolved and the salt is dissolved or finely suspended, and if necessary, the salt is removed from the reaction product. By extraction and removal, porous crosslinked polyvinyl alcohol having a specific surface area of 0.1 m ² /g or more can be produced with good reproducibility. To explain the present invention in detail, according to the present invention, porous crosslinked polyvinyl alcohol having a desired specific surface area can be easily produced from commercially available polyvinyl alcohol and a crosslinking agent. The polyvinyl alcohol used has a polymerization degree of several tens to several thousand, preferably 200 to 2000, and a saponification degree of 50 mol% or more, preferably 85 mol% or more. Polyvinyl alcohol is 2-30%, preferably 5-15%
It is dissolved in water and reacted with a crosslinking agent so that Examples of crosslinking agents include dialdehydes such as glyoxal, glutaraldehyde, and terephthalaldehyde; diepoxy compounds such as 1,2,3,4-diepoxybutane; bisepoxypropyl ether, ethylene glycol bisepoxypropyl ether, 1,4- Glycidyl ethers such as butanediol bisepoxypropyl ether; epihalohydrins such as epichlorohydrin and epibromohydrin;
Those capable of forming a crosslinking moiety having 1 or more carbon atoms are used. The crosslinking agent is usually used in an amount of 5 mol % or more based on the hydroxyl groups of polyvinyl alcohol. In the present invention, the reaction between polyvinyl alcohol and the crosslinking agent is carried out in water in which the linear polyvinyl alcohol is dissolved and the salt is dissolved or finely suspended. As the salt, both water-soluble salts and insoluble salts can be used. Water-soluble salts usually include chlorides such as sodium chloride, potassium chloride, and calcium chloride; nitrates such as sodium nitrate, potassium nitrate, and calcium nitrate;
Sulfates such as magnesium sulfate, phosphates such as sodium phosphate, etc. are used. These water-soluble salts are thought to have the effect of precipitating the polyvinyl alcohol from the reaction medium through a salting-out effect when the molecular weight increases due to the reaction of the polyvinyl alcohol with the crosslinking agent. The formation of a precipitate is estimated by the fact that the reaction medium becomes cloudy shortly after the start of the reaction).
Therefore, it is necessary to use these water-soluble salts at a concentration sufficient to exhibit the above-mentioned salting-out effect. The concentration varies depending on the type of salt, and for sodium chloride it is preferably 5-12%, but for calcium chloride it is preferably 5-12%.
20% or more. Generally speaking, the concentration of salt is 1
Used in the range of ~40%. As water-insoluble salts, sulfates such as calcium sulfate, barium sulfate, and lead sulfate, and phosphates such as calcium phosphate are usually used. The amount used is usually 5 to 70 g, preferably 20 to 60 g per 100 g of polyvinyl alcohol aqueous solution. These insoluble salts, unlike the water-soluble salts mentioned above, are included in the crosslinked polyvinyl alcohol during the crosslinking reaction. When these insoluble salts are then extracted from the resulting crosslinked product with an aqueous acid solution, the residue remains in the crosslinked product in the form of pores. Therefore, it is preferable to use as fine an insoluble salt as possible. The crosslinking reaction is preferably carried out by dissolving or suspending a salt in an aqueous polyvinyl alcohol solution, adding a crosslinking agent thereto, and suspending the mixture in an oily dispersion medium. As a dispersion medium, aromatic hydrocarbons such as toluene, benzene, chlorobenzene, dichlorobenzene and their halogen derivatives, n-heptane, n-hexane, liquid paraffin, cyclohexane, dichloromethane,
Aliphatic hydrocarbons such as dichloroethane, alicyclic hydrocarbons, and their halogen derivatives are used. These dispersion media are usually used alone, but two or more types may be used in combination. The amount of dispersion medium used is 2 times the amount of polyvinyl alcohol aqueous solution.
(capacity) times or more, preferably 3 to 6 (capacity) times. In addition, the dispersion medium contains ethyl cellulose, cellulose acetate butyrate,
It is preferable to add an oil-soluble dispersion stabilizer such as oil-soluble cellulose such as ethyl hydroxyethyl cellulose, gum arabic, sorbitan sesquioleate, sorbitan monooleate, or sorbitan monostearate. The amount is usually
It is 0.05-10%, preferably 0.1-5%. The crosslinking reaction is carried out at 0°C to 100°C, preferably
It is carried out at 20°C to 80°C for 1 hour to 20 hours, preferably 2 hours to 8 hours. During the crosslinking reaction, an acid such as hydrochloric acid or sulfuric acid or an alkali such as sodium hydroxide or potassium hydroxide is used as necessary. The crosslinked polyvinyl alcohol thus obtained is separated from the dispersion medium by filtration. Next, it is washed with a hydrophilic organic solvent such as acetone, and then with water. If an insoluble salt is used, the insoluble salt is then dissolved away with an acid aqueous solution, and then washed with water until it becomes neutral again. The porous crosslinked polyvinyl alcohol obtained by the method of the invention is useful as a filler for chromatography, particularly for aqueous gel permeation chromatography. It can also be made into an ion exchange resin by reacting with glyoxylic acid (see Japanese Patent Application No. 129745/1983). The present invention will be explained in more detail with reference to Examples below, but the present invention is not limited to the following Examples unless it exceeds the gist thereof. In addition, in the following examples, specific surface area, pore volume, and water content were measured by the following methods. Measurement of specific surface area and pore volume After thoroughly washing the resin with water, the water is replaced with acetone, and the acetone is further replaced with toluene. This resin was dried at 30° C. for 24 hours in a vacuum dryer at 10 mmHg, and the following measurements were performed. Specific surface area: BE using Cantersolve (manufactured by Yuasa Battery Co., Ltd.) using nitrogen gas adsorption
Measured by T. method. Pore volume: Mercury intrusion porosimeter (Carlo
Measurement of moisture content using Elva Co., Ltd. After thoroughly washing the resin, place it in a 10ml graduated cylinder and tap the bottom to accurately weigh out 10ml. This resin was dehydrated using a centrifuge at 350G for 5 minutes, and then its weight (a ₁ g) was accurately weighed. Next, this resin was dried in a vacuum dryer at 60° C. and 10 mmHg for 24 hours, and then the weight (a ₂ g) was accurately weighed again. Moisture content = a ₁ − a ₂ / a ₁ × 100 (%) Example 1 600 ml of dichloroethane was put into a three-necked flask (No. 1) equipped with a stirrer and a reflux condenser, and cellulose acetate butyrate (manufactured by Eastman Kodak Co., Ltd.) was added. , trademark CAB381-20) was dissolved. Separately, put 200 g of a 10% polyvinyl alcohol aqueous solution (the polyvinyl alcohol is made by Nippon Gosei Co., Ltd. and uses the trademark Gohsenol NL05) in a 500 ml three-necked flask equipped with a stirrer, and add 8 ml of a 25% glutaraldehyde aqueous solution to this while stirring. In addition,
Furthermore, 100 g of calcium sulfate dihydrate was added to form a slurry. After the slurry is sufficiently uniform, 1
After adding 12 ml of normal sulfuric acid and stirring rapidly, the mixture was dispersed in the above dispersion medium at room temperature. After stirring at room temperature for 1 hour, the mixture was heated at 60° C. for 2.5 hours to carry out a crosslinking reaction. After cooling to room temperature, add 100ml of acetone.
Washed 3 times with Next, wash with water, transfer again to a three-necked flask with a stirrer, and add 2N hydrochloric acid.
500 ml of the mixture was added, stirred at room temperature for 1 hour, and then filtered. This operation was repeated 10 times to remove calcium sulfate. After thoroughly washing the cross-linked polyvinyl alcohol from which calcium sulfate has been removed, the water content, specific surface area,
The pore volume was measured. As a result, the moisture content was 77.2%,
The specific surface area was 1.0 m ² /g and the pore volume was 191 ml/g. Examples 2 to 4 Porous, crosslinked polyvinyl alcohol was produced in the same manner as in Example 1, except that the amounts of the 25% aqueous glutaraldehyde solution and calcium sulfate dihydrate were changed as shown in Table 1. Table 2 shows the water content, specific surface area, and pore volume of the obtained resin.

【table】

[Table] Example 5 500 ml of toluene was placed in a three-necked flask (No. 1) equipped with a stirrer and a reflux condenser, and 7.5 g of ethyl cellulose (manufactured by Hercules Co., Ltd., trademark ethyl cellulose N-100) was dissolved therein. Separately, 500ml with stirrer and reflux condenser
Put 195.6g of 8% saline solution into a three-necked flask,
While stirring, add powdered polyvinyl alcohol (manufactured by Nippon Gosei Co., Ltd., trademark Gohsenol NL05) 20
g was added, dispersed, and heated at 90°C for 30 minutes to dissolve. After cooling to 0° C., 8 ml of 25% glutaraldehyde aqueous solution was added thereto. Further, 12 ml of 1N hydrochloric acid was added, and after stirring rapidly, the mixture was dispersed in the above dispersion medium. After dispersion, stir at room temperature for 1 hour, and then stir at 60℃ for 2 hours.
The crosslinking reaction was carried out by heating for half an hour. After cooling to room temperature, add 100ml of acetone.
It was washed three times with water, and then with water. The crosslinked polyvinyl alcohol thus obtained has a water content of 75.8
%, specific surface area 5.83 m ² /g, and pore volume 0.49 ml/g. Example 6 500 ml of dichloroethane was placed in a three-necked flask equipped with a stirrer and a reflux condenser, and 7.5 g of cellulose acetate butyrate (manufactured by Eastman Kodak Co., trade mark: CAB381-20) was dissolved therein. In a 500 ml three-necked flask separately equipped with a stirrer and reflux condenser, add 200 g of 10% saline, and while stirring, add 20 g of powdered polyvinyl alcohol (manufactured by Nippon Gosei Co., Ltd., trademark Gohsenol NL05).
was added, dispersed, and heated at 98°C for 1 hour to dissolve. After cooling to 0°C, 8 ml of 25% glutaraldehyde aqueous solution was added. Furthermore, 12 ml of 1N hydrochloric acid
was added, stirred quickly, and then dispersed in the above dispersion medium. The crosslinking reaction and washing after dispersion were carried out in the same manner as in Example 5. The crosslinked polyvinyl alcohol thus obtained has a water content of 77.1% and a specific surface area of 87.0 m ² /
g, and the pore volume was 0.54 ml/g. Example 7 In a three-necked flask equipped with a stirrer, 200 g of a 15% polyvinyl alcohol aqueous solution (the polyvinyl alcohol was manufactured by Nippon Gohsei Co., Ltd., trademark Gohsenol NL05 was used) was added, and 200 g of 20% saline was added thereto, followed by stirring and mixing. To this, 12 ml of 25% glutaraldehyde aqueous solution was added, followed by 24 ml of 1N sulfuric acid, and after stirring quickly, the mixture was dispersed in the same dispersion medium as in Example 6, and the reaction and washing were performed in the same manner as in Example 6. . The crosslinked polyvinyl alcohol obtained in this way is
The water content was 82.1% and the specific surface area was 78.6 m ² /g. Example 8 Add 95 ml of water to a 200 ml three-necked flask equipped with a stirrer and reflux condenser, and add sodium hydroxide.
4.3g was dissolved. Add powdered polyvinyl alcohol (manufactured by Nippon Gosei Co., Ltd.) to this sodium hydroxide aqueous solution.
15 g of Gohsenol NL05 (trade name) was dispersed. 80℃
After heating to dissolve the mixture, the temperature was lowered to 50°C, and 30g of calcium sulfate dihydrate was added to form a slurry. Then add 15.3 ml of epichlorohydrin and add 40
The crosslinking reaction was carried out for 7 and a half hours at °C. The obtained resin was filtered and washed with water, then calcium sulfate was removed using 2N hydrochloric acid 1.5, and then further washed with water. The resulting resin has a water content of 68.2% and a specific surface area of 1.3 m ² /
It was hot at g.

Claims (1)

[Claims] 1. Linear polyvinyl alcohol is dissolved, and
A method for producing porous crosslinked polyvinyl alcohol having a specific surface area of 0.1 m ² /g or more, which comprises reacting linear polyvinyl alcohol with a crosslinking agent in water in which a salt is dissolved or finely suspended. 2 linear polyvinyl alcohol is dissolved, and
Porous crosslinked polyvinyl alcohol according to claim 1, characterized in that linear polyvinyl alcohol and a crosslinking agent are reacted in water in which salt is finely suspended, and the salt is extracted and removed from the reaction product. manufacturing method. 3. Claim 1, characterized in that the crosslinking reaction is carried out by dispersing an aqueous solution containing a dissolved or suspended salt, dissolved linear polyvinyl alcohol, and a crosslinking agent in an oily reaction medium. Or the method for producing porous crosslinked polyvinyl alcohol according to item 2.