JPH09268232A - Modification of hydrophilic polymer and production of hydrophilic resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for modifying a hydrophilic polymer enabling efficient reaction of the hydrophilic polymer with a modifying agent independent of the size and shape of the hydrophilic polymer. SOLUTION: A water-absorbing resin (hydrophilic polymer) is crosslinked (modified) with a gaseous crosslinking agent (modifying agent). A secondary crosslinking structure can uniformly be introduced into the water-absorbing resin by this porcees with a simplified crosslinking process at a low cost. The method has excellent safety because of the absence of residual crosslinking agent. Various conventional reaction apparatuses such as a moving bed reactor can suitably be used as the treating apparatus, however, there is no particular restriction on the kind of the reactor.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a modification method for modifying a hydrophilic polymer such as a cross-linking treatment of a water absorbent resin, and a method for producing a hydrophilic resin.

[0002]

2. Description of the Related Art Conventionally, in a water-absorbent resin which is a kind of hydrophilic polymer, a cross-linking agent (modifying agent) is used to crosslink the water-absorbent resin in order to improve various properties such as water-absorbing properties. Treatment (secondary crosslinking treatment) is performed.
As a method of introducing a secondary crosslinked structure into the water-absorbent resin, a swelling liquid obtained by swelling the water-absorbent resin with a solvent, or a dispersion liquid in which the water-absorbent resin is dispersed using a dispersion medium, a crosslinking agent or A method of reacting the water-absorbent resin and the crosslinking agent in a so-called solid-liquid system by adding and mixing the solution is adopted. As the solvent and the dispersion medium, for example, hydrophilic compounds such as water and alcohol are used.

[0003]

However, the above-mentioned conventional method has various problems as described below. That is, since a solvent or a dispersion medium is used when reacting the water absorbent resin and the crosslinking agent, a post-treatment step such as a removing step or a drying step for removing the solvent or the dispersion medium after the reaction is required. Therefore, the work process of introducing the secondary crosslinked structure into the water absorbent resin is complicated. Further, the cross-linking agent, the solvent and the dispersion medium may remain in the water absorbent resin after the reaction, which may result in poor safety. Furthermore, after the reaction, it is difficult to remove / recover the excess crosslinking agent.

Furthermore, for example, when the water-absorbent resin is in the form of so-called fine powder, when the water-absorbent resin is mixed with a solvent or a dispersion medium, lumps are formed and the water-absorbent resin is swelled sufficiently and uniformly. Or cannot be dispersed. Therefore, depending on the size and shape of the water absorbent resin, the secondary crosslinked structure cannot be uniformly introduced into the water absorbent resin. Further, in order to sufficiently or uniformly swell or disperse the water-absorbent resin, the swelling liquid or the dispersion liquid must be stirred relatively violently, so that physical damage such as surface damage after the reaction is absorbed. Easy to receive resin. The lump means a state in which particles are aggregated into a lump.

Further, when the degree of crosslinking treatment of the water absorbent resin, for example, the crosslinking density and the crosslinking depth are made relatively large,
Since a relatively large amount of solvent or dispersion medium must be used, the water absorbent resin and the crosslinking agent cannot be reacted efficiently. Further, when a relatively large amount of the solvent or the dispersion medium is used, lumps are likely to be generated and the energy cost of the post-treatment process is increased.

Therefore, the above-mentioned conventional method causes the above-mentioned various problems in the reaction between the water absorbent resin and the crosslinking agent, that is, the reaction between the hydrophilic polymer and the modifier. Therefore, there is a demand for a novel method for modifying a hydrophilic polymer that can solve the above-mentioned various problems. That is, the present invention has been made in view of the above conventional problems, and an object thereof is to provide a novel method for modifying a hydrophilic polymer that does not cause the above various problems. Another object of the present invention is to provide a method for producing a hydrophilic resin.

[0007]

[Means for Solving the Problems] The inventors of the present application diligently studied a method for modifying a hydrophilic polymer in order to achieve the above object. As a result, by modifying the hydrophilic polymer with a gas modifier and modifying the hydrophilic polymer with the gas modifier, it is possible to easily and easily modify the hydrophilic polymer without causing the above-mentioned various problems. As a result, they have found what they can do and completed the present invention. It was also found that a hydrophilic resin can be easily and easily produced by reacting a hydrophilic polymer with a gaseous modifier.

That is, the method for modifying a hydrophilic polymer according to the first aspect of the present invention is characterized by modifying the hydrophilic polymer with a gaseous modifier in order to solve the above problems. The method for modifying a hydrophilic polymer according to the invention of claim 2 is
In order to solve the above problems, in the method for modifying a hydrophilic polymer according to claim 1, the modifying agent is a cross-linking agent. In order to solve the above-mentioned problems, a method for modifying a hydrophilic polymer according to a third aspect of the present invention is the method for modifying a hydrophilic polymer according to the first or second aspect, wherein the hydrophilic polymer is a water-absorbent resin. It is characterized by being.

According to the above method, since the hydrophilic polymer is modified with the gaseous modifier, the solvent and the dispersion medium, which are required in the conventional method, are unnecessary. Therefore, as compared with the conventional method, post-treatment steps such as a removing step and a drying step are not required, so that the modification work step is simplified and the cost is not increased. In addition, since the modifier and the solvent and the dispersion medium do not remain in the hydrophilic polymer after modification,
Excellent safety. Furthermore, since it is modified with a gaseous modifier, the hydrophilic polymer and the modifier can be reacted efficiently, and after modification, the excess modifier can be removed and recovered very easily and easily. In addition, the recovered denaturing agent can be easily reused.

Moreover, since it is modified with a gaseous modifier,
It can be uniformly modified regardless of the size and shape of the hydrophilic polymer. Therefore, for example, a hydrophilic polymer having a shape that cannot be handled by conventional methods such as a sheet shape, a film shape, a plate shape, or a block shape, or a porous hydrophilic polymer can be modified. Further, for example, a so-called fine powdery hydrophilic polymer can be modified.
That is, the shape and size of the hydrophilic polymer to be modified does not matter. Furthermore, the hydrophilic polymer is not subject to physical damage such as destruction of the surface after modification.

When the modifier is a cross-linking agent,
The hydrophilic polymer can be subjected to a crosslinking treatment. Further, when the hydrophilic polymer is a water-absorbing resin, various properties such as its water-absorbing property can be improved by modification.

In order to solve the above-mentioned problems, the method for producing a hydrophilic resin according to a fourth aspect of the present invention is characterized by reacting a hydrophilic polymer with a gaseous modifier.

According to the method of claim 4, since the hydrophilic polymer is reacted with the gaseous modifier, the solvent and the dispersion medium which are required in the conventional method are unnecessary. Therefore, as compared with the conventional method, post-treatment steps such as a removal step and a drying step are not required, so that the working step of the above reaction is simplified and the cost is not required. Further, since the modifier, the solvent and the dispersion medium do not remain in the hydrophilic resin obtained as the reaction product, the safety is excellent. further,
Since it reacts with the gaseous modifier, the hydrophilic polymer and the modifier can be efficiently reacted, and after the reaction, the excess modifier can be removed and recovered extremely easily and easily. In addition, the recovered denaturant can be easily reused. Thereby, the hydrophilic resin can be easily and easily manufactured.

Hereinafter, the present invention will be described in detail. In the modification method according to the present invention, the hydrophilic polymer is modified by bringing the hydrophilic polymer into contact with a gaseous modifier. Further, in the production method according to the present invention, a hydrophilic polymer as a reaction product is obtained by reacting a hydrophilic polymer with a gaseous modifier. Note that the modification specifically means, for example, a crosslinking treatment (secondary crosslinking treatment) or the like. The reaction between the hydrophilic polymer and the gaseous modifier specifically includes, for example, crosslinking reaction, addition reaction, substitution reaction, esterification reaction and the like.

The modifier may be in a gas state (gaseous state) when it is brought into contact with the hydrophilic polymer. That is, the denaturing agent becomes a gas under the gasification condition of its boiling point or higher, and in the gas state, a compound capable of reacting with the reactive group of the hydrophilic polymer, that is, a reaction in a so-called solid-gas system There is no particular limitation as long as it is a compound that can be used. Alternatively, the modifier becomes a gas under the gasification condition of its boiling point or higher and liquefies after coming into contact with the hydrophilic polymer, and reacts with the reactive group of the hydrophilic polymer in the liquid state. Or a compound capable of
It may be a compound which is solidified after contact with the hydrophilic polymer and can react with the reactive group of the hydrophilic polymer in the solid state. In short, the modifier may be in a gaseous state when it is brought into contact with the hydrophilic polymer,
The state (gaseous, liquid or solid) of the modifier when reacting with the reactive group of the hydrophilic polymer does not matter.

A so-called cross-linking agent is suitable as the modifier. Specific examples of the cross-linking agent include ethylene oxide (boiling point: 10.7 ° C./760 mmHg),
Propylene oxide (boiling point: 34.2 ° C / 760mm
Hg) and other alkylene oxide compounds; ethyleneimine (boiling point: 56 ° C / 760 mmHg), propyleneimine (boiling point: 67 ° C / 760 mmHg) and other alkyleneimine compounds; ethylene glycol diglycidyl ether (boiling point: 125 ° C / 5 mmHg), neo Pentyl glycol diglycidyl ether (boiling point: 125 ° C / 1mmH
g), glycerol triglycidyl ether (boiling point: 1
95 ° C./1.5 mmHg) and other polyglycidyl ether compounds; ethylene carbonate (boiling point: 100 ° C./5 m
mHg), propylene carbonate (boiling point: 242 ° C /
An alkylene carbonate compound such as 760 mmHg);
Ethylene glycol (boiling point: 70 ° C / 3mmHg), diethylene glycol (boiling point: 244 ° C / 760mmH)
g), triethylene glycol (boiling point: 287 ° C./76
0mmHg), glycerin (boiling point: 290 ° C / 760m
Polyhydric alcohol compounds such as mHg); ethylenediamine (boiling point: 116 ° C / 760 mmHg), hexamethylenediamine (boiling point: 196 ° C / 760 mmHg), diethylenetriamine (boiling point: 207 ° C / 760 mmHg),
Triethylenetetramine (boiling point: 287 ° C / 760mm
Hg), tetramethylethylenediamine (boiling point: 120
C./760 mmHg) and other polyvalent amine compounds; epichlorohydrin (boiling point: 62 ° C./100 mmHg) and other haloepoxy compounds; glutaraldehyde (boiling point: 72 ° C.)
/ 10 mmHg), glyoxal (boiling point: 51 ° C./7
76 mmHg) and other polyaldehyde compounds; ethylene sulfide (boiling point: 53 ° C./760 mmHg), propylene sulfide (boiling point: 70 ° C./760 mmHg) and other alkylene sulfide compounds; and the like. These modifiers may be used alone, or two or more kinds may be appropriately mixed and used. By mixing and using two or more types of modifiers, it is possible to perform several types of modification on the hydrophilic polymer at the same time, that is, in one step.

To bring the above-exemplified compounds into a gas state,
The vapor pressure may be set higher than the pressure in the denaturing system (hereinafter referred to as the processing system). That is, if necessary, the inside of the treatment system may be heated to a temperature equal to or higher than the boiling point of the modifier, or the pressure inside the treatment system may be transformed so that the pressure in the treatment system becomes lower than the vapor pressure of the modifier. Further, by carrying out both of them at the same time, the modifier can be brought into a gas state.

Specifically, ethylene oxide will be described as an example. As is clear from the temperature-vapor pressure relationship shown in Table 1, ethylene oxide contains, for example, about 5 kg.
It is gasified at a temperature of 50 ° C. or higher under the pressurization condition of f / cm ² . Therefore, the so-called solid-gas reaction can be carried out by appropriately setting the gasification conditions depending on the compound used as the modifier.

[0019]

[Table 1]

The hydrophilic polymer which can be modified (hereinafter referred to as treatment) by the modification method according to the present invention is
It is not particularly limited, and it may have a reactive group and may be solid or gel. As the above reactive group,
Carboxyl groups are particularly preferred. The hydrophilic polymer preferably has a crosslinked structure inside. The hydrophilic polymer specifically has a crosslinked structure inside,
In addition, partially neutralized poly (meth) acrylic acid, for example, a water-absorbent resin can be mentioned.

The above-mentioned hydrophilic polymer can be obtained, for example, by polymerizing a monomer composition containing acrylic acid or a salt thereof (hereinafter referred to as acrylic acid (salt)) as a main component. Specific examples of the hydrophilic polymer include crosslinked polyacrylic acid partially neutralized products, hydrolyzates of starch-acrylonitrile graft polymers, neutralized products of starch-acrylic acid graft polymers, and vinyl acetate. -Saponified product of acrylic acid ester copolymer, hydrolyzate of acrylonitrile copolymer or acrylamide copolymer or cross-linked product thereof, cross-linked product of carboxymethyl cellulose, cross-linked product of cationic monomer, isobutylene-maleic anhydride copolymerization Examples thereof include crosslinked products, copolymerized crosslinked products of 2-acrylamido-2-methylpropanesulfonic acid and acrylic acid, polyethylene oxide crosslinked products, and copolymerized crosslinked products of methoxypolyethylene glycol and acrylic acid. Among these exemplified hydrophilic polymers, a crosslinked polyacrylic acid (salt) is more preferable. The crosslinked product of polyacrylic acid (salt) has 50 mol% of acid groups contained in the crosslinked product.
It is preferably neutralized within the range of 90 mol%. As the salt, an alkali metal salt, an alkaline earth metal salt, an ammonium salt, a hydroxyammonium salt,
Amine salts and alkylamine salts are preferred.

The monomer composition may contain, in addition to acrylic acid (salt), if necessary, a hydrophilic monomer copolymerizable with the acrylic acid (salt). Specific examples of the hydrophilic monomer include methacrylic acid, crotonic acid, (anhydrous) maleic acid, fumaric acid, itaconic acid, cinnamic acid, sorbic acid, β-acryloyloxypropionic acid, and 2- (Meth) acryloylethanesulfonic acid, 2-
(Meth) acryloylpropanesulfonic acid, 2- (meth) acrylamido-2-methylpropanesulfonic acid,
Anionic unsaturated monomers such as vinyl sulfonic acid, styrene sulfonic acid, allyl sulfonic acid, vinyl phosphonic acid and 2- (meth) acryloyloxyethyl phosphoric acid, and alkali metal salts and alkaline earth metal salts thereof, Ammonium salt, alkylamine salt; acrylamide, methacrylamide, N-ethyl (meth) acrylamide,
N-n-propyl (meth) acrylamide, N-isopropyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, 2-hydroxyethyl (meth) acrylate, 2-hydroxypropyl (meth) acrylate, methoxy polyethylene glycol ( (Meth) acrylate, polyethylene glycol mono (meth) acrylate, vinylpyridine, N-vinylpyrrolidone, N-acryloylpiperidine, N-acryloylpyrrolidine and other nonionic unsaturated monomers; N, N-dimethylaminoethyl (meth) acrylate , N, N-diethylaminoethyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylate, N, N-dimethylaminopropyl (meth) acrylamide and other cationic unsaturated monomers, and These quaternary compound (e.g., a reaction product of an alkyl halide, the reaction products of dialkyl sulfate);
And the like. These hydrophilic monomers may be used alone or in combination of two or more kinds.

When the monomer composition contains acrylic acid (salt) as a main component, the amount of the hydrophilic monomer other than the acrylic acid (salt) used is 30 mol% of the whole monomer composition.
The following is more preferable, and 10 mol% or less is further preferable.

The hydrophilic polymer obtained by (co) polymerizing the above monomer composition preferably has a crosslinked structure (primary crosslinked structure) inside. The above-mentioned crosslinked structure can be easily introduced by using an internal crosslinking agent when (co) polymerizing the monomer composition and copolymerizing or reacting the monomer composition with the internal crosslinking agent. You can The hydrophilic polymer may be a self-crosslinking type that does not require an internal crosslinking agent.

Examples of the internal cross-linking agent include compounds having a plurality of vinyl groups (polymerizable unsaturated groups) in the molecule;
It has at least one vinyl group in the molecule and at least one functional group capable of reacting with the reactive group of the monomer composition.
And a compound having a plurality of functional groups capable of reacting with the reactive group in the molecule. These internal crosslinking agents may be used alone or in combination of two or more kinds.

Specific examples of the compound having a plurality of vinyl groups in the molecule include N, N'-methylenebis (meth) acrylamide, (poly) ethylene glycol di (meth) acrylate and (poly) propylene glycol di. (Meth) acrylate, trimethylolpropane tri (meth) acrylate, trimethylolpropane di (meth) acrylate, glycerin tri (meth) acrylate, glycerin acrylate methacrylate, ethylene oxide modified trimethylolpropane tri (meth) acrylate, pentaerythritol tetra ( (Meth) acrylate, dipentaerythritol hexa (meth) acrylate, N, N-diallyl acrylamide,
Poly (meth) s such as triallyl cyanurate, triallyl isocyanurate, triallyl phosphate, triallyl amine, diallyloxyacetic acid, N-methyl-N-vinyl acrylamide, bis (N-vinyl carboxylic acid amide), tetraallyloxyethane Aryloxy alkane etc. are mentioned.

The compound having at least one vinyl group in the molecule and at least one functional group capable of reacting with the reactive group has, for example, at least one hydroxyl group, epoxy group or cationic group. An ethylenically unsaturated compound is mentioned. Specific examples of the compound include glycidyl (meth) acrylate,
Examples thereof include N-methylol acrylamide and dimethylaminoethyl (meth) acrylate.

Examples of the compound having a plurality of functional groups capable of reacting with the reactive group in the molecule include compounds having at least two hydroxyl groups, epoxy groups, cationic groups, isocyanate groups and the like. Specific examples of the compound include (poly) ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ethylene glycol, polyethylene glycol,
Examples include propylene glycol, glycerin, pentaerythritol, ethylenediamine, ethylene carbonate, polyethyleneimine, aluminum sulfate and the like.

Of the above-exemplified internal crosslinking agents, it is more preferable to use a compound having a plurality of vinyl groups in the molecule. By using a compound having a plurality of vinyl groups in the molecule, various properties of the resulting hydrophilic polymer, for example, water absorption properties when the hydrophilic polymer is a water-absorbent resin, are further improved. The amount of the internal cross-linking agent used with respect to the hydrophilic monomer depends on the combination of the hydrophilic monomer and the internal cross-linking agent, etc., but is in the range of 0.005 mol% to 3 mol% with respect to the hydrophilic monomer. Is preferable, and the range of 0.01 mol% to 1.5 mol% is more preferable.

When the monomer composition is (co) polymerized, hydrophilic polymers such as starch and its derivatives, cellulose and its derivatives, polyvinyl alcohol, polyacrylic acid (salts) and cross-linked products thereof, etc. Chain transfer agents such as hypophosphorous acid and salts thereof may be added to the reaction system.

As the polymerization method for (co) polymerizing the monomer composition, various known polymerization forms such as aqueous solution polymerization, reverse phase suspension polymerization, bulk polymerization, precipitation polymerization and the like can be adopted and are not particularly limited. Not something. Among these, aqueous solution polymerization in which the monomer composition is polymerized in an aqueous solution state, reverse phase suspension polymerization, the polymerization reaction can be easily controlled, and various properties of the resulting hydrophilic polymer are further improved. preferable.

Further, when the monomer composition is (co) polymerized, a radical polymerization initiator, an active energy ray such as an ultraviolet ray or an electron ray can be used. Specific examples of the above radical polymerization initiator include potassium persulfate, sodium persulfate, ammonium persulfate, t-butyl hydroperoxide, hydrogen peroxide, and 2,2′-azobis (2-amidinopropane). Dihydrochloride, 2,2'-
Examples thereof include peroxides such as azobisisobutyronitrile, benzoyl peroxide, cumene hydroperoxide, and di-t-butyl peroxide. These radical polymerization initiators may be used alone or in combination of two or more kinds. Furthermore, when an oxidizing radical polymerization initiator is used, the oxidizing radical polymerization initiator and sulfites such as sodium sulfite and sodium hydrogen sulfite, bisulfites, thiosulfates, formamidinesulfinic acid, sulfuric acid It may be used as a redox initiator by combining with a reducing agent such as iron or L-ascorbic acid. The amount of the polymerization initiator used with respect to the hydrophilic monomer depends on the combination of the hydrophilic monomer and the polymerization initiator and the like, but is 0.001 mol% to 2 mol% with respect to the hydrophilic monomer. The range is preferable, and the range of 0.01 mol% to 0.5 mol% is more preferable.

The shape of the hydrophilic polymer is not particularly limited, and examples thereof include particles such as spheres, granules, scales, and flat particles; fibrous; sheet-like, film-like, plate-like, block-like. , Indefinite shape; and so on. Further, the hydrophilic polymer may be porous or may be so-called sponge having open cells. Further, the size of the hydrophilic polymer is not particularly limited and may be so-called fine powder. That is, the hydrophilic polymer does not have to have a predetermined shape and size when treated with the modifier, and may have a shape and size according to its application and the like. That is, the modification method according to the present invention does not matter the shape and size of the hydrophilic polymer to be treated.

The treatment conditions for treating the hydrophilic polymer with the modifier are not particularly limited as long as the modifier can exist in a gaseous state. For example, the processing pressure may be any of reduced pressure, normal pressure, and increased pressure. Incidentally, when the degree of treatment of the hydrophilic polymer, for example, the crosslinking density and the crosslinking depth are made relatively large, it may be preferable to carry out the treatment under normal pressure rather than under reduced pressure. In some cases, treatment under pressure is preferable to treatment under pressure. That is, the processing pressure may be appropriately set according to the desired degree of processing. By manipulating the treatment pressure, the degree of treatment of the hydrophilic polymer can be easily controlled.

The treatment temperature depends on the treatment pressure, the reactivity between the hydrophilic polymer and the modifier, and the like, but may range from room temperature to 300 ° C.
Is preferable, the range of 100 ° C. to 250 ° C. is more preferable, and the range of 130 ° C. to 230 ° C. is further preferable.
The reaction time may be set according to the treatment temperature, the treatment pressure, or the reactivity between the hydrophilic polymer and the modifier, and is not particularly limited, but is from several seconds to 2 hours, preferably several hours. It is sufficient to set the time to about 1 minute to 1 hour. The reaction between the hydrophilic polymer and the modifier is a reaction system without water, that is,
It progresses even in the so-called anhydrous state. That is, the modification method according to the present invention is not affected by the presence or absence of water in the treatment system.

The processing apparatus is constructed so that a hydrophilic polymer (hereinafter, simply referred to as a polymer) and a gaseous modifier (hereinafter, simply referred to as a gas) can be sufficiently brought into contact with each other, that is, a solid There is no particular limitation as long as it has a configuration capable of carrying out a gas-based reaction. As the treatment device, various known reaction devices can be adopted. For example, a moving bed type reaction device in which a polymer is brought into contact with a gas while gently moving; while a polymer is suspended and suspended in a gas. , A fluidized bed reactor in which the gas is contact-reacted; a polymer is used as a fixed bed, and the gas is a single-phase flow,
Fixed-bed reactor for flowing and contacting reaction in countercurrent or parallel flow; stirring tank reactor for contact reaction while stirring the polymer and gas in the tank with stirring blades; gas flow of polymer An air flow type reaction device that advances a contact reaction with the gas while being blown away by the above;

As the moving bed type reactor, specifically,
For example, as shown in FIG. 1 or FIG. 2, a countercurrent vertical reactor in which the polymer is moved downward and gas is caused to flow upward; as shown in FIG. 3, the polymer is moved downward and Cross-flow type reactor for laterally flowing gas; as shown in FIG. 4 or FIG. 5, moving grate type reactor for horizontally moving polymer on a belt conveyor and upwardly flowing gas; shown in FIG. As shown in FIG. 7, a rotary kiln (rotary furnace) type reactor in which the polymer and the gas are moved in the same direction by rotating the device as shown in FIG. Examples include a multi-stage furnace-type reactor in which gas is moved upward while sequentially moving from one stage to the next stage. still,
The moving grate type reactor shown in FIG. 5 is particularly suitable when the polymer is in a sheet form or the like.

As the fluidized bed type reactor, specifically,
For example, as shown in FIG. 8 or 9, a perforated plate or a wire mesh,
A gas-solid fluidized bed reactor in which a polymer is suspended and suspended by flowing gas upwards in a device equipped with an insert such as a pipe; as shown in FIG. 11. A high-speed fluidized bed reactor in which the polymer is suspended and suspended by the above; a jet-bed reactor in which a polymer is suspended and suspended by injecting a gas upward as shown in FIG. To be

As the stirring tank type reactor, specifically,
For example, as shown in FIG. 12, a gas-solid stirring tank reactor in which the polymer and gas in the tank are stirred by stirring blades;
As shown in FIG. 5, a multi-stage impeller tank type reactor in which a plurality of partition plates are provided in the vessel and the polymer and gas are sequentially moved from the lower stage to the upper stage while being stirred by a stirring blade;

Specific examples of the air flow type reaction device include a gas-solid air flow type reaction device which blows away a polymer by an air flow of gas as shown in FIG.

The structure of the processing apparatus, that is, the reaction apparatus is not limited to the above-exemplified structure. Further, the processing apparatus may employ either a batch system (batch system) or a continuous system. For example, a closed reaction device such as an autoclave can also be suitably used as the processing device. That is, the denaturing method according to the present invention can be preferably carried out in either a batch system or a continuous system. Then, the hydrophilic polymer can be uniformly treated by bringing the hydrophilic polymer and the gaseous modifier into sufficient contact with each other using a treatment device under predetermined treatment conditions. Since the denaturing method according to the present invention uses gas, denaturing can be carried out sufficiently and reliably in a relatively short time.

As described above, the method of modifying the hydrophilic polymer according to the present invention is a method of modifying the hydrophilic polymer with a gaseous modifier. The method for modifying the hydrophilic polymer according to the present invention is a method in which the modifying agent is a crosslinking agent. Furthermore, the method for modifying a hydrophilic polymer according to the present invention is a method in which the hydrophilic polymer is a water absorbent resin.

According to the above method, the solvent and the dispersion medium, which are required in the conventional method, are unnecessary. Therefore, as compared with the conventional method, the denaturing work process is simplified and the cost is not increased. In addition, since the modifier and the solvent and the dispersion medium do not remain in the hydrophilic polymer after modification,
Excellent safety. Furthermore, the hydrophilic polymer and the modifying agent can be reacted efficiently, and after modification, the excess modifying agent can be removed and recovered very easily and easily. It can be used easily.

Moreover, the hydrophilic polymer can be uniformly modified regardless of its size and shape. Therefore, even a hydrophilic polymer having a shape which cannot be dealt with by the conventional method or a porous hydrophilic polymer can be modified. Also,
For example, even a so-called fine powdery hydrophilic polymer can be modified. That is, the shape and size of the hydrophilic polymer to be modified does not matter. Furthermore, the hydrophilic polymer is not subject to physical damage such as destruction of the surface after modification.

When the modifier is a cross-linking agent,
The hydrophilic polymer can be subjected to a crosslinking treatment. Further, when the hydrophilic polymer is a water-absorbing resin, various properties such as its water-absorbing property can be improved by modification.

As described above, the method for producing a hydrophilic resin according to the present invention is a method of reacting a hydrophilic polymer with a gaseous modifier. According to the above method, since the hydrophilic polymer and the gaseous modifier are reacted, the solvent and the dispersion medium which are required in the conventional method are unnecessary. Therefore, as compared with the conventional method, post-treatment steps such as a removal step and a drying step are not required, so that the working step of the above reaction is simplified and the cost is not required. Further, since the modifier, the solvent and the dispersion medium do not remain in the hydrophilic resin obtained as the reaction product, the safety is excellent. Furthermore, since it is reacted with a gaseous modifier, the hydrophilic polymer and the modifier can be reacted efficiently, and
After the reaction, the excess denaturing agent can be removed and recovered very easily and easily, and the recovered denaturing agent can be easily reused. Thereby, the hydrophilic resin can be easily and easily manufactured.

[0047]

The present invention will be described in more detail with reference to the following Examples and Comparative Examples, but the present invention is not limited thereto. The hydrophilic polymers (4 types) to be modified were produced by the following production method. The water retention amount of the water absorbent resin as the modified hydrophilic polymer (hydrophilic resin) and the water absorption amount under pressure were measured by the following methods.
In the following description, unless otherwise specified.
“Parts” indicates “parts by weight”.

(1) Production Method of Hydrophilic Polymer Four types of hydrophilic polymers were produced by the production methods shown in the following (a) to (d).

(A) So-called nitrogen sealing and heat removal
In a reaction vessel capable of heating, a neutralization ratio of 70 mol% sodium acrylate 30 wt% aqueous solution 5,0
00 parts were charged. In other words, acrylic acid 3
An aqueous solution containing 71 parts, 1,129 parts of sodium acrylate, and 3,500 parts of water was charged.

Next, 6.76 parts of polyethylene glycol diacrylate as an internal cross-linking agent was dissolved in the aqueous solution, and nitrogen gas was blown into the aqueous solution for 30 minutes (bubbling) to expel dissolved oxygen. Next, 1.8 parts of potassium persulfate which is a radical polymerization initiator and 0.09 part of L-ascorbic acid which is a reducing agent were added to the above aqueous solution with stirring. Then, the aqueous solution was polymerized under a nitrogen stream at a polymerization initiation temperature of 30 ° C.

About 5 minutes after the initiation of the polymerization, the temperature in the reaction system reached 70 ° C. Then, the mixture was heated and stirred for 2 hours while maintaining the temperature in the reaction system at about 70 ° C. to complete the polymerization reaction. As a result, a hydrous gel-like crosslinked polymer composed of sodium polyacrylate was obtained.

The obtained hydrogel crosslinked polymer was taken out and subdivided using a meat chopper, and then the subdivided product was spread on a 60-mesh wire net and dried with a hot air drier for 15 minutes.
It was dried with hot air at 0 ° C. for 135 minutes. Then, the dried product was pulverized with a coffee mill and further classified with a wire mesh of 20 mesh (mesh size 840 μm) to obtain a particulate cross-linked polymer having an average particle diameter of about 400 μm, that is, a hydrophilic polymer. A polymer (hereinafter referred to as hydrophilic polymer (a)) was obtained. The above-mentioned hydrophilic polymer (a) was in a so-called "dry-flowing" state without moisture or stickiness.

(B) So-called nitrogen sealing and heat removal
Acrylic acid 1,0 was placed in a reaction vessel capable of heating.
00 parts, internal cross-linking agent tetraaryloxyethane 5
Parts and 3,500 parts of water were charged, mixed and dissolved to obtain an aqueous solution. Next, dissolved oxygen was expelled by blowing nitrogen gas into the aqueous solution for 30 minutes (bubbling). Then, with stirring, 6 parts of hydrogen peroxide, which is a radical polymerization initiator, and 1 part of 2,2′-azobis (2-amidinopropane) dihydrochloride, and 0.3 parts of L-ascorbic acid are added to the above aqueous solution with stirring. Parts were added. afterwards,
The aqueous solution was polymerized under a nitrogen stream at a polymerization initiation temperature of 25 ° C. Then, while maintaining the temperature in the reaction system substantially constant, the mixture was stirred for about 2 hours to complete the polymerization reaction. This allows
A hydrogel cross-linked polymer made of polyacrylic acid was obtained.

Next, the obtained water-containing gel-like crosslinked polymer was taken out and subdivided.
By adding 868 parts by weight of an aqueous solution and uniformly kneading, about 75 mol% of the carboxyl groups in the polymer
Neutralized. That is, about 75 mol% of the carboxyl groups in the polymer was converted to sodium salt.

The hydrogel crosslinked polymer after neutralization was taken out and dried at 150 ° C. using a drum dryer. The dried product is then ground using a coffee mill and further 2
By classifying with a 0 mesh wire mesh, a particulate cross-linked polymer having an average particle diameter of about 410 μm, that is, a hydrophilic polymer (hereinafter referred to as hydrophilic polymer (b)) was obtained. The above-mentioned hydrophilic polymer (b) was in a so-called "smooth" state without moisture or stickiness.

(C) So-called nitrogen sealing and heat removal
A reaction vessel capable of heating was added with a sodium acrylate 35% by weight aqueous solution 5,0 having a neutralization ratio of 80 mol%.
00 parts were charged. In other words, acrylic acid 2
An aqueous solution consisting of 81 parts, 1,469 parts of sodium acrylate, and 3,250 parts of water was charged.

Next, N, which is an internal cross-linking agent, is added to the aqueous solution.
Dissolve 2.2 parts of N'-methylenebisacrylamide,
Bubbling nitrogen gas into the aqueous solution for 30 minutes (Bubbling)
By doing so, dissolved oxygen was expelled. Next, 4 parts of 2,2′-azobis (2-amidinopropane) dihydrochloride was added to the above aqueous solution with stirring. 5 after adding
After stirring for 1 minute, the aqueous solution became cloudy and formation of white fine particles of 2,2′-azobis (2-amidinopropane) diacrylate was observed in the reaction system.

Immediately thereafter, 1.8 parts of potassium persulfate and 0.09 part of L-ascorbic acid were added to the above aqueous solution with stirring. Then, the aqueous solution was polymerized under a nitrogen stream at a polymerization initiation temperature of 25 ° C.

Approximately 5 minutes after the initiation of polymerization, the temperature in the reaction system reached 80 ° C. Then, the mixture was heated and stirred for 2 hours while maintaining the temperature in the reaction system at about 75 ° C. to complete the polymerization reaction. As a result, a hydrous gel-like crosslinked polymer composed of sodium polyacrylate was obtained.

The obtained hydrous gel-like cross-linked polymer was taken out and subdivided using a meat chopper, and then the subdivided product was spread on a 60-mesh wire net and dried with a hot air drier for 15 minutes.
It was dried with hot air at 0 ° C. for 125 minutes. Then, the dried product is pulverized with a coffee mill and further classified with a wire mesh of 20 mesh to obtain a particulate cross-linked polymer having an average particle diameter of about 400 μm, that is, a hydrophilic polymer (hereinafter, referred to as hydrophilic polymer). Combined (referred to as (c)) was obtained. In addition, since 2,2′-azobis (2-amidinopropane) diacrylate has a property as a foaming agent, the hydrophilic polymer (c) described above is used.
Was porous, and its average pore diameter was 50 μm. Moreover, the hydrophilic polymer (c) was in a so-called "dry-flowing" state without moisture or stickiness.

(D) By further classifying the hydrophilic polymer (b) obtained by the production method of (b) above with a metal mesh of 100 mesh (mesh size 150 μm),
The 93-mesh passage product was collected. Thus, a hydrophilic polymer (hereinafter referred to as hydrophilic polymer (d)) was obtained. The above-mentioned hydrophilic polymer (d) was in a so-called "smooth" state without moisture or stickiness.

(2) Water Retention A non-woven tea bag type bag (6
cm × 6 cm), the opening was heat-sealed, and then immersed in a 0.9 wt% sodium chloride aqueous solution (physiological saline). After 30 minutes, the tea bag type bag was pulled up and drained at 250 G for 3 minutes using a centrifuge, and then the weight W ₁ (g) of the bag was measured. Also,
The same operation was performed without using the water absorbent resin, and the weight W ₀ (g) at that time was measured. And these weights W ₁ ·
From W ₀ , the water retention amount (g / g) was calculated according to the following formula: Water retention amount (g / g) = (weight W ₁ (g) −weight W ₀ (g)) / weight of water absorbent resin (g) .

(3) Water Absorption under Pressurization First, a measuring device used for measuring the water absorption under pressure will be briefly described below with reference to FIG.

As shown in FIG. 15, the measuring device is a balance 1
A container 2 having a predetermined capacity placed on the balance 1, an outside air suction pipe 3, a conduit 4 made of silicone resin,
It comprises a glass filter 6 and a measuring section 5 mounted on the glass filter 6. The container 2 has an opening 2a at its top and an opening 2b at its side, and the outside air suction pipe 3 is fitted into the opening 2a, while the conduit 4 is attached to the opening 2b. Have been.
Further, the container 2 contains a predetermined amount of physiological saline (0.9% by weight).
Aqueous sodium chloride solution) 12 is contained. The lower end of the outside air suction pipe 3 is submerged in the physiological saline 12. The outside air suction pipe 3 is provided to keep the pressure in the container 2 at substantially the atmospheric pressure. The glass filter 6 has a diameter of 55 mm. The container 2 and the glass filter 6 are in communication with each other by the conduit 4. The position and height of the glass filter 6 with respect to the container 2 are fixed.

The measuring unit 5 is composed of a filter paper 7 and a supporting cylinder 9.
And a wire net 10 attached to the bottom of the support cylinder 9 and a weight 11. Then, the measuring unit 5 places the filter paper 7 and the support cylinder 9 (that is, the wire mesh 10) on the glass filter 6.
Are placed in this order, and inside the support cylinder 9, that is,
A weight 11 is placed on a wire net 10. Wire mesh 1
No. 0 is made of stainless steel and is formed to 400 mesh (mesh size: 38 μm). And at the time of measurement,
The water-absorbent resin 1 having a predetermined amount and a predetermined particle size
5 are evenly distributed. In addition, wire mesh 1
0, that is, the height of the contact surface between the metal mesh 10 and the water-absorbent resin 15 is set to be equal to the height of the lower end surface 3 a of the outside air suction pipe 3. Weight 11 is wire mesh 1
0, that is, the weight is adjusted so that a load of 50 g / cm ² can be uniformly applied to the water absorbent resin 15.

The water absorption amount under pressure was measured by using the measuring device having the above-mentioned structure. The measuring method will be described below.

First, a predetermined preparatory operation such as putting a predetermined amount of physiological saline 12 into the container 2; fitting the outside air suction pipe 3 into the container 2 was performed. Next, the filter paper 7 was placed on the glass filter 6. Further, in parallel with this placing operation, 0.9 g of the water-absorbent resin is placed inside the support cylinder 9, that is, on the metal net 10.
Was evenly spread, and the weight 11 was placed on the water absorbent resin 15.

Then, on the filter paper 7, the wire mesh 10, that is,
The support cylinder 9 on which the water-absorbent resin 15 and the weight 11 were placed was placed so that the center part thereof coincided with the center part of the glass filter 6.

Then, the weight W ₂ (g) of the physiological saline solution 12 absorbed by the water-absorbent resin 15 was measured on the balance 1 for 60 minutes from the time when the supporting cylinder 9 was placed on the filter paper 7. It was measured using. Further, the same operation is performed without using the water absorbent resin 15, and the weight at that time, that is, the weight of the physiological saline solution 12 absorbed by the filter paper 7 or the like other than the water absorbent resin 15 is measured using the balance 1. And blank weight W
₃ (g). And from these weights W ₂ · W ₃ ,
Water absorption amount under pressure (g / g) = (weight W ₂ (g) -weight W ₃ (g)) /
The amount of water absorption (g / g) under pressure was calculated according to the weight (g) of the water absorbent resin.

Example 1 A hydrophilic polymer (a) 10 was placed in an autoclave (treatment device) having a volume of 1 L equipped with a stirring blade.
After charging 0 part and purging with nitrogen, the pressure in the reaction system was set to 5 kgf / cm ² with nitrogen gas. Next, the inside of the reaction system was heated to 180 ° C. with stirring, and when the temperature reached 180 ° C., 3 parts of ethylene oxide as a crosslinking agent (modifying agent) was introduced into the reaction system. At this time, the pressure in the reaction system was 7 Kgf / cm ^{2 to} 8 Kgf / cm ² , and the ethylene oxide was in a gaseous state. Next, a crosslinking treatment (modification) was performed by stirring for 10 minutes while maintaining the temperature in the reaction system at 180 ° C.

After completion of the treatment, the autoclave was opened, and the water-absorbent resin as the crosslinked hydrophilic polymer (hydrophilic resin) was taken out. The water-absorbent resin was in the form of particles, was free from moisture and stickiness, and was in a so-called "dry flow" state. Moreover, the formation of lumps was not observed.

The infrared absorption spectra of the surface of the hydrophilic polymer (a) and the surface of the water absorbent resin were measured by FT-IR (Fourier transform infrared spectroscopy). As a measuring device,
"Nippon Bio-Rad Laborat
FTS-45 "manufactured by ories KK) was used. Moreover, the diffuse reflection (DR) spectroscopy was adopted as the measurement method (sampling method). FIG. 16 shows a chart of infrared absorption spectrum of the surface of the hydrophilic polymer (a). A chart of infrared absorption spectrum of the surface of the water absorbent resin is shown in FIG.

In the chart of FIG. 16, the absorption peak of the carboxyl group present on the surface of the hydrophilic polymer (a) appears at 1728.3 cm ^-1 . On the other hand, in the chart of FIG. 17, the absorption peak is 17
It appears in a state of being shifted to 53.8 cm ^-1 . From this, it is understood that the carboxyl group present on the surface of the hydrophilic polymer (a) formed an ester with ethylene oxide by the crosslinking treatment. That is, it can be seen that the surface of the hydrophilic polymer (a) was modified with ethylene oxide.

The water retention capacity and the water absorption capacity under pressure of the obtained water absorbent resin were measured by the above-mentioned method. As a result, the water retention capacity of the water absorbent resin was 34 g / g, and the water absorption capacity under pressure was 21 g.
/ G. Further, the water retention amount and the water absorption amount under pressure of the hydrophilic polymer (a) were measured according to the above method. As a result, the water retention capacity of the hydrophilic polymer (a) was 43 g / g, and the water absorption capacity under pressure was 7 g / g. Table 2 shows the above results.

Example 2 An autoclave having a volume of 1 L and equipped with a stirring blade was charged with 100 parts of the hydrophilic polymer (b), and after substituting with nitrogen, the pressure in the reaction system was adjusted to 5 K with nitrogen gas.
It was set to gf / cm ² . Next, the temperature in the reaction system was raised to 180 ° C. with stirring, and when the temperature reached 180 ° C.,
3 parts of ethylene oxide was introduced into the reaction system. At this time, the pressure in the reaction system is 7 Kgf / cm ^{2 to} 8 Kgf / c.
m ² and the ethylene oxide was in a gaseous state. Next, a crosslinking treatment was carried out by stirring for 30 minutes while maintaining the temperature in the reaction system at 180 ° C.

After completion of the treatment, the autoclave was opened and the water-absorbent resin as the hydrophilic polymer which had been subjected to the crosslinking treatment was taken out. The water-absorbent resin was in the form of particles, was free from moisture and stickiness, and was in a so-called "dry flow" state. Moreover, the formation of lumps was not observed.

The water retention capacity of the resulting water absorbent resin is 28 g /
The water absorption amount under pressure was 21 g / g. Further, the water retention capacity and the water absorption capacity under pressure of the hydrophilic polymer (b) were measured according to the above method. As a result, the hydrophilic polymer (b)
Had a water retention capacity of 32 g / g and a water absorption capacity under pressure of 8 g / g. Table 2 shows the above results.

Example 3 An autoclave having a volume of 1 L equipped with a stirring blade was charged with 100 parts of the hydrophilic polymer (c), and after substituting with nitrogen, the pressure in the reaction system was adjusted to 5 K with nitrogen gas.
It was set to gf / cm ² . Next, the temperature in the reaction system was raised to 180 ° C. with stirring, and when the temperature reached 180 ° C.,
3 parts of ethylene oxide was introduced into the reaction system. At this time, the pressure in the reaction system is 7 Kgf / cm ^{2 to} 8 Kgf / c.
m ² and the ethylene oxide was in a gaseous state. Next, a crosslinking treatment was carried out by stirring for 60 minutes while maintaining the temperature in the reaction system at 180 ° C.

After the completion of the treatment, the autoclave was opened and the water-absorbent resin as the hydrophilic polymer which had been subjected to the crosslinking treatment was taken out. The water-absorbent resin was in the form of particles, was free from moisture and stickiness, and was in a so-called "dry flow" state. Moreover, the formation of lumps was not observed.

The water retention capacity of the resulting water absorbent resin is 29 g /
The water absorption under pressure was 22 g / g. Further, the water retention amount and the water absorption amount under pressure of the hydrophilic polymer (c) were measured according to the above method. As a result, the hydrophilic polymer (c)
Had a water retention capacity of 33 g / g and a water absorption capacity under pressure of 8 g / g. Table 2 shows the above results.

Example 4 100 parts of the hydrophilic polymer (a) was charged into an autoclave having a volume of 1 L equipped with a stirring blade, and after substituting with nitrogen, the pressure in the reaction system was adjusted to 4 K with nitrogen gas.
It was set to gf / cm ² . Next, the temperature in the reaction system was raised to 150 ° C. with stirring, and when the temperature reached 150 ° C.,
4.8 parts of ethylene oxide was introduced into the reaction system. At this time, the pressure in the reaction system was 5 Kgf / cm ² , and the ethylene oxide was in a gaseous state. Next, a crosslinking treatment was carried out by stirring for 45 minutes while maintaining the temperature in the reaction system at 150 ° C.

After completion of the treatment, the autoclave was opened and the water-absorbent resin as the hydrophilic polymer which had been subjected to the crosslinking treatment was taken out. The water-absorbent resin was in the form of particles, was free from moisture and stickiness, and was in a so-called "dry flow" state. Moreover, the formation of lumps was not observed. The water absorption capacity of the obtained water absorbent resin is 30 g / g, and the water absorption capacity under pressure is 18 g / g.
Met. Table 2 shows the above results.

Example 5 Instead of 100 parts of the hydrophilic polymer (c) in Example 3, 100 parts of the hydrophilic polymer (a) which had been previously heat-dried at 180 ° C. for a predetermined time was used. Other than the above, the same crosslinking treatment as in Example 3 was performed.

After completion of the treatment, the autoclave was opened and the water-absorbent resin as the hydrophilic polymer which had been subjected to the crosslinking treatment was taken out. The water-absorbent resin was in the form of particles, was free from moisture and stickiness, and was in a so-called "dry flow" state. Moreover, the formation of lumps was not observed. The water absorption capacity of the obtained water absorbent resin is 29 g / g, and the water absorption capacity under pressure is 22 g / g.
Met. Table 2 shows the above results.

As is clear from the above results, it is understood that the modification method according to the present invention is not affected by whether or not the hydrophilic polymer contains water. In other words, it can be seen that the result of the modification is not affected even if the hydrophilic polymer to be modified contains or does not contain water.

Example 6 Instead of 100 parts of the hydrophilic polymer (c) in Example 3, 10 parts of the hydrophilic polymer (d) were used.
The same crosslinking treatment as in Example 3 was carried out except that 0 part was used.

After completion of the treatment, the autoclave was opened and the water-absorbent resin as the hydrophilic polymer which had been subjected to the crosslinking treatment was taken out. The water-absorbent resin was in the form of particles, was free from moisture and stickiness, and was in a so-called "dry flow" state. Moreover, the formation of lumps was not observed.

The water retention capacity of the resulting water absorbent resin was 23 g /
The water absorption under pressure was 11 g / g. Further, the water retention amount and the water absorption amount under pressure of the hydrophilic polymer (d) were measured according to the above method. As a result, the hydrophilic polymer (d)
Had a water retention capacity of 27 g / g and a water absorption capacity under pressure of 6 g / g. Table 2 shows the above results.

Example 7 100 parts of the hydrophilic polymer (a) was charged into an autoclave having a volume of 1 L equipped with a stirring blade, and after substituting with nitrogen, the pressure in the reaction system was adjusted to 5 K with nitrogen gas.
It was set to gf / cm ² . Next, the temperature in the reaction system was raised to 200 ° C. with stirring, and when the temperature reached 200 ° C.,
3 parts of ethylene oxide was introduced into the reaction system. At this time, the pressure in the reaction system is 7 Kgf / cm ^{2 to} 8 Kgf / c.
m ² and the ethylene oxide was in a gaseous state. Next, a crosslinking treatment was performed by stirring for 10 minutes while maintaining the temperature in the reaction system at 200 ° C.

After the completion of the treatment, the autoclave was opened and the water-absorbent resin as the hydrophilic polymer which had been subjected to the crosslinking treatment was taken out. The water-absorbent resin was in the form of particles, was free from moisture and stickiness, and was in a so-called "dry flow" state. Moreover, the formation of lumps was not observed. The water absorption capacity of the obtained water absorbent resin is 35 g / g, and the water absorption capacity under pressure is 19 g / g.
Met. Table 2 shows the above results.

Example 8 An autoclave having a capacity of 1 L equipped with a stirring blade was charged with 100 parts of the hydrophilic polymer (a) which had been previously heat-dried at 180 ° C. for a predetermined time, and after nitrogen substitution, nitrogen was added. The pressure in the reaction system is 5 Kgf / c with gas
m ² . Next, the inside of the reaction system is set to 200 while stirring.
The temperature was raised to 200 ° C., and when the temperature reached 200 ° C., 3 parts of ethylene oxide was introduced into the reaction system. At this time, the pressure in the reaction system was 7 Kgf / cm ^{2 to} 8 Kgf / cm ² , and the ethylene oxide was in a gaseous state. Next, a crosslinking treatment was performed by stirring for 60 minutes while maintaining the temperature in the reaction system at 200 ° C.

After the completion of the treatment, the autoclave was opened and the water-absorbent resin as the hydrophilic polymer which had been subjected to the crosslinking treatment was taken out. The water-absorbent resin was in the form of particles, was free from moisture and stickiness, and was in a so-called "dry flow" state. Moreover, the formation of lumps was not observed. The water retention capacity of the obtained water absorbent resin is 33 g / g, and the water absorption capacity under pressure is 22 g / g.
Met. Table 2 shows the above results.

Example 9 100 parts of the hydrophilic polymer (a) was charged into an autoclave having a volume of 1 L equipped with a stirring blade, and after substituting with nitrogen, the pressure in the reaction system was adjusted to 5 K with nitrogen gas.
It was set to gf / cm ² . Next, the temperature in the reaction system was raised to 220 ° C. with stirring, and when the temperature reached 220 ° C.,
3 parts of propylene oxide as a crosslinking agent (modifying agent) was introduced into the reaction system. At this time, the pressure in the reaction system is 7K
gf / cm ^{2 to} 8 kgf / cm ² , and propylene oxide was in a gaseous state. Next, a crosslinking treatment (modification) was performed by stirring for 60 minutes while maintaining the temperature in the reaction system at 220 ° C.

After the completion of the treatment, the autoclave was opened and the water-absorbent resin as the hydrophilic polymer which had been subjected to the crosslinking treatment was taken out. The water-absorbent resin was in the form of particles, was free from moisture and stickiness, and was in a so-called "dry flow" state. Moreover, the formation of lumps was not observed. The water absorption capacity of the obtained water absorbent resin is 29 g / g, and the water absorption capacity under pressure is 19 g / g.
Met. Table 2 shows the above results.

Example 10 An autoclave having a volume of 1 L equipped with a stirring blade was charged with 100 parts of the hydrophilic polymer (a) which had been previously heat-dried at 180 ° C. for a predetermined time, and after nitrogen substitution, nitrogen was added thereto. The gas pressure in the reaction system is 5 Kgf /
cm ² . Next, the inside of the reaction system is stirred for 24 hours.
The temperature was raised to 0 ° C., and when the temperature reached 240 ° C., 3 parts of ethylene oxide was introduced into the reaction system. At this time, the pressure in the reaction system was 8 Kgf / cm ^{2 to} 9 Kgf / cm ² , and the ethylene oxide was in a gaseous state. Next, a crosslinking treatment was performed by stirring for 3 minutes while maintaining the temperature in the reaction system at 240 ° C.

After the completion of the treatment, the autoclave was opened and the water-absorbent resin as the hydrophilic polymer which had been subjected to the crosslinking treatment was taken out. The water-absorbent resin was in the form of particles, was free from moisture and stickiness, and was in a so-called "dry flow" state. Moreover, the formation of lumps was not observed. The water absorption capacity of the obtained water absorbent resin is 30 g / g, and the water absorption capacity under pressure is 22 g / g.
Met. Table 2 shows the above results.

Example 11 100 parts of ethylene glycol diglycidyl ether as a cross-linking agent (modifying agent) was charged into a stainless steel container, and the upper opening of the container was covered with a 200-mesh stainless wire mesh. . next,
50 parts of the hydrophilic polymer (a) was evenly spread on the metal net.

After that, ethylene glycol diglycidyl ether is vaporized by heating the container, and gaseous ethylene glycol diglycidyl ether is brought into contact with the hydrophilic polymer (a) for 10 minutes to carry out a crosslinking treatment (modification). I went.

After the completion of the treatment, the water-absorbent resin as the hydrophilic polymer which had been subjected to the crosslinking treatment was recovered. The water absorbent resin is
It was in the form of particles, had no moisture or stickiness, and was in a so-called "dry flow" state. Moreover, the formation of lumps was not observed. The water retention capacity of the obtained water absorbent resin was 36 g / g, and the water absorption rate under pressure was 11 g / g. Table 2 shows the above results.

Comparative Example 1 100 parts of the hydrophilic polymer (a) was charged into an autoclave having a volume of 1 L and equipped with a stirring blade, and after substituting with nitrogen, the pressure in the reaction system was adjusted to 7 K with nitrogen gas.
It was set to gf / cm ^{2 to} 8 kgf / cm ² . Next, the temperature in the reaction system was raised to 180 ° C. with stirring to 180 ° C.
The mixture was stirred at 60 ° C for 60 minutes. That is, the treatment was performed without using ethylene oxide as a crosslinking agent.

After the completion of the treatment, the autoclave was opened and the treated water absorbent resin as a hydrophilic polymer was taken out. The water retention capacity of the comparative water absorbent resin is 40 g /
The water absorption amount under pressure was 8 g / g, and the water absorption amount under pressure was not improved. Table 2 shows the above results.

Comparative Example 2 100 parts of the hydrophilic polymer (a) was charged into an autoclave having a volume of 1 L and equipped with a stirring blade, and then the temperature in the reaction system was raised to 180 ° C. with stirring to a temperature of 180. The mixture was stirred at 60 ° C for 60 minutes. That is,
The treatment was performed without using ethylene oxide as a cross-linking agent and without displacing or pressurizing the reaction system with nitrogen gas.

After the completion of the treatment, the autoclave was opened and the treated water absorbent resin as a hydrophilic polymer was taken out. The water retention capacity of the comparative water absorbent resin is 42 g /
The water absorption under pressure was 7 g / g, and the water absorption under pressure was not improved. Table 2 shows the above results.

[Comparative Example 3] While flowing 100 parts of the hydrophilic polymer (d) using a fluidized-drying apparatus, the hydrophilic polymer (d) was treated with a pressure type spray nozzle as a crosslinking agent. The two were mixed by intermittently spraying 10 parts of a 3% by weight aqueous solution of ethylene glycol. However, the above mixing became non-uniform, and a large amount of lumps were produced.

By heating the above mixture to 180 ° C. and heating for 60 minutes while maintaining the temperature at 180 ° C.,
Processing was performed. After the treatment was completed, the mixture was classified with a 20-mesh wire net to separate the passing product. As a result, a comparative water-absorbent resin as a treated hydrophilic polymer was obtained.

A large amount of lumps was observed in the above water absorbent resin for comparison. The water absorption capacity of the obtained comparative water absorbent resin was 26 g / g, the water absorption capacity under pressure was 6 g / g, and the mixing of the hydrophilic polymer (d) and the ethylene glycol 3% by weight aqueous solution was uneven. Therefore, the amount of water absorption under pressure was not improved. That is, it was found that the water absorption amount under pressure was remarkably inferior to the result of Example 6. Table 2 shows the above results.

[0107]

[Table 2]

As is clear from the results of Examples 1 to 11, it is understood that the water absorption amount under pressure is improved by subjecting the hydrophilic polymer to the crosslinking treatment. In addition, Comparative Examples 1 to
As is clear from the comparison with the result of 3, the modification method according to the present invention can efficiently react the hydrophilic polymer with the crosslinking agent (modifying agent). Further, it can be seen that the water absorbent resin as the hydrophilic resin can be easily and easily manufactured by the manufacturing method according to the present invention.

[0109]

As described above, the method for modifying a hydrophilic polymer according to claim 1 of the present invention is a method for modifying a hydrophilic polymer with a gaseous modifier. As described above, the method for modifying a hydrophilic polymer according to claim 2 of the present invention is a method in which the modifying agent is a crosslinking agent. As described above, the method for modifying a hydrophilic polymer according to claim 3 of the present invention is a method in which the hydrophilic polymer is a water-absorbent resin.

As a result, the solvent and dispersion medium, which were required in the conventional method, are no longer needed. Therefore, as compared with the conventional method, the denaturing work process is simplified and the cost is not increased. Further, since the modifier, the solvent and the dispersion medium do not remain in the modified hydrophilic polymer, the safety is excellent. Furthermore, the hydrophilic polymer and the modifying agent can be reacted efficiently, and after modification, the excess modifying agent can be removed and recovered very easily and easily. It has various effects that it can be easily used.

Moreover, the hydrophilic polymer can be uniformly modified regardless of its size and shape. Therefore, even a hydrophilic polymer having a shape which cannot be dealt with by the conventional method or a porous hydrophilic polymer can be modified. Also,
For example, even a so-called fine powdery hydrophilic polymer can be modified. That is, the shape and size of the hydrophilic polymer to be modified does not matter. Further, various effects that the hydrophilic polymer is not subjected to physical damage such as destruction of the surface after modification are also exhibited.

When the modifier is a cross-linking agent,
The hydrophilic polymer can be subjected to a crosslinking treatment. Further, when the hydrophilic polymer is a water-absorbent resin, it is possible to improve various characteristics such as water-absorption characteristics by modification.

The method for producing a hydrophilic resin according to claim 4 of the present invention is a method of reacting a hydrophilic polymer with a gaseous modifier as described above. According to the above method, since the hydrophilic polymer and the gaseous modifier are reacted, the solvent and the dispersion medium which are required in the conventional method are unnecessary. Therefore, as compared with the conventional method, post-treatment steps such as a removal step and a drying step are not required, so that the working step of the above reaction is simplified and the cost is not required. Further, since the modifier, the solvent and the dispersion medium do not remain in the hydrophilic resin obtained as the reaction product, the safety is excellent. Furthermore, since it is reacted with a gaseous modifier, the hydrophilic polymer and the modifier can be reacted efficiently, and
After the reaction, the excess denaturing agent can be removed and recovered very easily and easily, and the recovered denaturing agent can be easily reused. As a result, the hydrophilic resin can be easily and easily manufactured.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a schematic configuration of a reaction apparatus suitably used in a denaturing method according to the present invention.

FIG. 2 is an explanatory diagram showing a schematic configuration of another reaction apparatus preferably used in the modification method according to the present invention.

FIG. 3 is an explanatory diagram showing a schematic configuration of still another reaction apparatus suitably used in the modification method according to the present invention.

FIG. 4 is an explanatory diagram showing a schematic configuration of still another reaction apparatus suitably used in the modification method according to the present invention.

FIG. 5 is an explanatory diagram showing a schematic configuration of still another reaction apparatus suitably used for the modification method according to the present invention.

FIG. 6 is an explanatory diagram showing a schematic configuration of still another reaction apparatus suitably used for the modification method according to the present invention.

FIG. 7 is an explanatory diagram showing a schematic configuration of still another reaction apparatus suitably used in the denaturing method according to the present invention.

FIG. 8 is an explanatory diagram showing a schematic configuration of still another reaction apparatus suitably used in the modification method according to the present invention.

FIG. 9 is an explanatory diagram showing a schematic configuration of still another reaction apparatus suitably used for the modification method according to the present invention.

FIG. 10 is an explanatory diagram showing a schematic configuration of still another reaction apparatus suitably used in the modification method according to the present invention.

FIG. 11 is an explanatory diagram showing a schematic configuration of still another reaction apparatus suitably used for the modification method according to the present invention.

FIG. 12 is an explanatory view showing a schematic configuration of still another reaction apparatus suitably used in the modification method according to the present invention.

FIG. 13 is an explanatory diagram showing a schematic configuration of still another reaction apparatus suitably used in the denaturing method according to the present invention.

FIG. 14 is an explanatory diagram showing a schematic configuration of still another reaction apparatus suitably used in the denaturing method according to the present invention.

FIG. 15 is a schematic cross-sectional view of a measuring device used for measuring a water absorption amount under pressure, which is one of the performances exhibited by a water absorbent resin as a hydrophilic polymer modified by a modifying method according to the present invention.

FIG. 16 is a chart of infrared absorption spectrum of the surface of the hydrophilic polymer (a) used in one example of the present invention.

FIG. 17 is a chart of the infrared absorption spectrum of the surface of the water absorbent resin obtained in one example of the present invention.

[Explanation of symbols]

 1 Balance 2 Container 3 Outside Air Suction Pipe 4 Conduit 5 Measuring Section 6 Glass Filter 7 Filter Paper 9 Support Cylinder 10 Wire Mesh 11 Weight 12 Physiological Saline 15 Water Absorbent Resin (Hydrophilic Polymer)

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Tadao Shimomura 1 992 Nishikioki, Kamahama-ku, Aboshi-ku, Himeji-shi, Hyogo Nihon Shokubai Co., Ltd.

Claims (4)

[Claims] 1. A method for modifying a hydrophilic polymer, which comprises modifying the hydrophilic polymer with a gaseous modifier. 2. The method for modifying a hydrophilic polymer according to claim 1, wherein the modifying agent is a crosslinking agent. 3. The method for modifying a hydrophilic polymer according to claim 1, wherein the hydrophilic polymer is a water absorbent resin. 4. A method for producing a hydrophilic resin, which comprises reacting a hydrophilic polymer with a gaseous modifier.