JPH0820640A - Liquid-absorbing resin, liquid-absorbing resin composite and their production - Google Patents

Abstract

PURPOSE:To obtain a liquid-absorbing resin consisting of a crosslinked polydioxorane, having water-absorbing characteristics with small metallic ion effect and high salt resistance, also excellent in film formability, flexibility and heat sealability, etc., thus useful for e.g. hygienic materials such as napkins and agricultural water holding materials. CONSTITUTION:This liquid-absorbing resin consists of a crosslinked polydioxorane [e.g. a crosslinked polymer obtained by crosslinking through either irradiating an aqueous solution of polydioxorane made up of recurring units of the formula with active energy rays or heating following incorporation of a crosslinking agent bearing polyfunctional group reactive with the OH group in the polydioxorane molecule (e.g. polyfunctional isocyanate, polyfunctional carboxylic acid) into the aqueous solution].

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid-absorbent resin, a liquid-absorbent resin composite and a method for producing them.
More specifically, the present invention relates to a liquid-absorbent resin, a liquid-absorbent resin composite comprising a crosslinked polymer having an oxymethylene-oxyethylene repeating unit and having a crosslinked structure, and a method for producing them.

[0002]

2. Description of the Related Art In recent years, a water-absorbing polymer capable of absorbing hundreds of times its own weight of water has been developed and used as a sanitary material such as a disposable diaper or a napkin, a water retention agent for agriculture, or a water blocking agent for cables. ing. However, since these water-absorbing polymers are often cross-linked polymers obtained by polymerizing ionic monomers such as acrylates, metal ions such as body fluids such as urine and blood and seawater. The water absorption capacity in the solution containing was lower than that of pure water. Further, since many water-absorbent polymers are powdery, they are difficult to use as they are, and secondary processing such as mixing with pulp or coating with a binder on a film is required.

As the water-absorbent polymer having improved salt resistance,
It is known that polyethylene oxide is crosslinked with isocyanates (Japanese Patent Publication No. 50-36280). On the other hand, as a water-absorbent resin that does not require secondary processing, there has been proposed one obtained by crosslinking and molding polyethylene oxide with ionizing radiation (JP-A-4-34563). However, these resins are inferior in durability such as non-uniform cross-linking and decrease in water absorption performance over time, or have adhesiveness when absorbing moisture, which makes them difficult to handle.

[0004]

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a liquid-absorbent resin composed of crosslinked polydioxolane, a liquid-absorbent resin composite and a method for producing them.

Another object of the present invention is to provide a liquid-absorbent resin and a liquid-absorbent resin composed of a cross-linked polymer having an oxymethylene-oxyethylene repeating unit represented by the following chemical formula (I) and having a cross-linked structure. An object of the present invention is to provide composites and a method for producing them.

[0006]

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Still another object of the present invention is to provide a liquid-absorbent polymer which has an excellent liquid-absorbing property without being affected by metal ions in a solution and which can be easily processed according to the purpose and application. An object is to provide a liquid-absorbent resin, a liquid-absorbent resin composite that can be used, and a method for producing the same.

[0008]

These objects are achieved by a liquid absorbing resin composed of crosslinked polydioxolane.

These objects are also achieved by a liquid-absorbent resin comprising a crosslinked polymer having a repeating unit of oxymethylene-oxyethylene represented by the following chemical formula (I) and having a crosslinked structure.

[0010]

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These objects are achieved by a method for producing a liquid-absorbent resin, which is characterized by crosslinking polydioxolane.

The present invention is also a method for producing the liquid-absorbent resin, wherein the polydioxolane is crosslinked by irradiating an aqueous solution of the polydioxolane with an active energy ray. The present invention further provides crosslinking of polydioxolane by blending a crosslinking agent having a polyfunctional reactive group capable of reacting with a hydroxyl group in the polydioxolane molecule and heating the mixture to produce the absorbent resin. Is the way.

These objects are also achieved by a liquid-absorbent resin composite obtained by fixing a crosslinked polydioxolane on a substrate.

The present invention is also the liquid-absorbent resin composite, wherein the substrate is a fibrous, sponge-like, film-like or porous substrate.

These objects are also achieved by a method for producing a liquid-absorbent resin composite, which comprises depositing polydioxolane on a substrate and then crosslinking the polydioxolane.

The present invention also provides a method for producing the liquid-absorbent resin composite, wherein the cross-linking of polydioxolane is carried out by applying an aqueous solution of the polydioxolane to a substrate and then irradiating with active energy irradiation rays. is there. The present invention further relates to the cross-linking of polydioxolane in which a compound comprising a cross-linking agent having a polyfunctional reactive group capable of reacting with a hydroxyl group in the polydioxolane molecule is attached to a substrate,
Then, the method for producing the liquid-absorbent resin composite is carried out by heating. The present invention is also the method for producing the liquid-absorbent resin composite, wherein the substrate is a fibrous, sponge-like, film-like or porous substrate.

[0017]

The liquid absorbing resin of the present invention comprises a crosslinked polydioxolane. The shape is not particularly limited, and can be variously selected, for example, a hydrogel, a film shape, a fibrous shape, a granular shape, a scaly shape, or the like, depending on the purpose and application of the resin.

The polydioxolane used in the present invention can be obtained by, for example, 1,3-dioxolane, 2-
Methyl-1,3-dioxolane, 4-methyl-1,3-
At least one monomer selected from monomers such as dioxolane and 2,2'-diethyl-1,3-dioxolane may be cationically polymerized. Further, other monomers copolymerizable with these monomers may be copolymerized. Examples of the copolymerizable monomer include styrene; (meth) acrylic acid;
Unsaturated hydrocarbons such as ethylene and propylene; cyclic ethers such as trioxane, ethylene oxide, propylene oxide and tetrahydrofuran; γ-butyrolactone,
Lactones or lactams such as glycolide, lactide, ε-caprolactone, ε-caprolactam can be mentioned. Polydioxolane can also be obtained by polycondensation of formaldehyde and ethylene glycol.

The polydioxolane used in the present invention is not limited to those obtained by these methods.

As the initiator, for example, a heteropolyacid such as phosphotungstic acid or phosphomolybdic acid, or an organometallic compound such as triethylaluminum, aluminum isopropoxide or titanium isopropoxide can be used.

The polydioxolane thus obtained has an average number average molecular weight of 5,000 to 10,000,000, preferably 10,000 to 1,000,000.

The crosslinked polydioxolane of the present invention is obtained by irradiating polydioxolane with active energy radiation or
Alternatively, it can be obtained by reacting with a crosslinking agent and crosslinking. Also,
It can also be obtained by polymerizing 1,3-dioxolane in the presence of a polyfunctional polyepoxy compound such as ethylene glycol diglycidyl ether. From the viewpoint of handling the resulting liquid-absorbent resin and the like, a method in which polydioxolane is irradiated with active energy irradiation rays or reacted with a crosslinking agent to crosslink is preferable.

The polydioxolane can be crosslinked by irradiation with an active energy ray such as an electron beam, gamma ray or X-ray, or by reacting with a hydroxyl group of polydioxolane such as polyfunctional isocyanate or polycarboxylic acid. Crosslinking by reaction with the resulting crosslinker is mentioned. Of these, crosslinking with active energy irradiation rays is preferable from the viewpoints of uniformity of crosslinking, water absorption performance of the resulting water-absorbent polymer, and the like.

As the active energy irradiation ray, an electron beam,
There are gamma rays, X rays and the like, and gamma rays and electron rays are preferable.

The irradiation dose of the active energy irradiation ray is 0.5 to 200 Mrad, preferably 1 to 20 M.
It is rad. That is, if the irradiation dose is less than 0.5 Mrad, the polydioxolane may not crosslink, whereas if the irradiation dose exceeds 200 Mrad, the crosslinking may proceed excessively and sufficient water absorption may not be obtained.

In the case of cross-linking by irradiation with active energy ray, polydioxolane is preferably cross-linked in the state of an aqueous solution. By irradiating in the state of an aqueous solution, a liquid absorbing resin excellent in water absorption can be obtained. The concentration of polydioxolane in the aqueous solution is 0.5 to 90% by weight, preferably 1 to 50% by weight. That is, if the concentration of polydioxolane is less than 0.5% by weight, it becomes difficult to sufficiently crosslink, while if it exceeds 90% by weight, the water absorption performance may be significantly reduced.

As the cross-linking agent used for cross-linking the polydioxolane by adding the cross-linking agent, any cross-linking agent having a polyfunctional reactive group capable of reacting with the hydroxyl group contained in the polydioxolane molecule can be used. Of these, polyfunctional isocyanates and polycarboxylic acids are preferable.

As the polyfunctional isocyanate, for example, 2,4-tolylene diisocyanate (TDI), 2,6
-Tolylene diisocyanate, propane diisocyanate, hexane diisocyanate, decane diisocyanate, ω, ω'-dipropyl ether diisocyanate,
Thiodiethyl diisocyanate, hexanefluoropropane diisocyanate, 1,3-benzene-ω, ω'-
Diisocyanate, 1,4-dimethylnaphthalene-ω,
ω'-diisocyanate, 1,3-dimethylbenzene-
2,4-diisocyanate, naphthalene-1,4-diisocyanate, biphenyl-4,4'-diisocyanate, 2-nitrobiphenyl-4,4'-diisocyanate, 3,3'-dimethoxybiphenyl-4,4'-diisocyanate , Diphenylmethane 4,4'-diisocyanate, 3,3'-dichlorodiphenyldimethylmethane 4,4'-diisocyanate, 1-methylbenzene 2,
4,6-triisocyanate, naphthalene-1,3,7
-Triisocyanate, biphenyl-2,4,4'-triisocyanate, triphenylmethane-4,4 ', 4
Examples include ″ -triisocyanate, a trimer of TDI, a polyisocyanate compound having an isocyanurate ring, an adduct polyisocyanate compound, and a buret polyisocyanate compound.

Examples of the polyvalent carboxylic acid include maleic acid, fumaric acid, oxalic acid, succinic acid, adipic acid, citric acid, phthalic acid, malonic acid, sebacic acid, pyromellitic acid, trimellitic acid, aspartic acid and polycarboxylic acid. Examples include aspartic acid, polyacrylic acid, polyhydroxyacrylic acid and the like.

The cross-linking agent having these polyfunctional reactive groups is 0.5 to 5 equivalents per hydroxyl group in polydioxolane,
Preferably, 0.6 to 2 equivalents are used. That is, 0.
If the amount is less than 5 equivalents, crosslinking may be insufficient and a liquid absorbing resin may not be obtained. On the other hand, if it exceeds 5 equivalents, a large amount of uncrosslinked crosslinking agent may remain, or the water absorbing performance of the resulting liquid-absorbent resin may deteriorate.

When the polydioxolane is cross-linked using a cross-linking agent, a predetermined amount of the cross-linking agent is added to the solution of polydioxolane, and then 25 to 250 ° C., preferably 50.
It is carried out by heating at a temperature of ~ 200 ° C.

The solvent used for preparing the polydioxolane solution is not particularly limited as long as the polydioxolane can be dissolved, and can be appropriately selected depending on the type of the cross-linking agent and the reaction conditions, for example, chloroform, tetrachloride. Examples thereof include halogen-containing compounds such as carbon, water, acetone, methyl ethyl ketone, dioxane, toluene and the like.

The polydioxolane which has been irradiated with an actinic energy ray or crosslinked with a crosslinking agent can be used as a hydrogel as it is, or can be used after crushing and drying if necessary. In addition, a film-shaped or sheet-shaped liquid-absorbent resin can be obtained by coating a release paper or the like with irradiation, irradiating, and peeling off the release paper after the irradiation.

The liquid-absorbent resin composed of the crosslinked polydioxolane obtained in this manner is more effective than the conventionally known partially neutralized polyacrylic acid crosslinked polymer in the influence of the salt concentration in the solution and multivalent Less susceptible to metal ions,
It has excellent water absorption and salt resistance. Further, since the film-forming property is good, it can be used as a water-absorbent film or sheet which is easy to handle and process. Since polydioxolane is a thermoplastic resin, it has a heat-sealing property and can be formed into a bag or attached to another substrate. Further, it has good compatibility with other thermoplastic resins such as polyethylene, polypropylene, and ethylene-vinyl acetic acid copolymer, and can be kneaded with these thermoplastic resins to impart water absorption and antistatic properties. The crosslinked polydioxolane hydrogel has good gel strength and transparency. This product can be suitably used as an artificial lens, an artificial joint gel, a biomedical electrode, a vibration proof material, a sound proof material, or a water retention agent for agriculture and horticulture. In addition, since the crosslinked polydioxolane hydrogel has a cloud point at about 70 ° C., it is also useful as a temperature-sensitive resin and can be applied to various sensors and drug delivery systems.

In the present invention, the crosslinked polydioxolane may be fixed to the substrate. As the base material, polyethylene, polyester, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyurethane, rayon,
Non-woven fabrics, woven fabrics made of cupra, pulp, cotton, wool, etc.
Fibrous base materials such as mesh sheets, papers, fiber aggregates, sponge base materials such as polyurethane and cellulose, polyethylene, polyester, polypropylene, polyvinyl chloride, polyvinylidene chloride, polyvinyl alcohol, ethylene-vinyl acetic acid copolymer Film-like base materials made of various synthetic resins such as coalescence and metal foils such as aluminum foil, and porous base materials such as foamed phenolic resin, foamed polyethylene, foamed polypropylene, foamed polystyrene, and pumice, etc. Various selections can be made according to the requirements. The base material to which the crosslinked polydioxolane is fixed is not limited to these base materials. The ratio of the crosslinked polydioxolane and the base material is not particularly limited and can be appropriately set according to the purpose and application. Generally, 0.01 to 1000 parts by weight of polydioxolane, preferably 0. 1-20
It is in the range of 0 parts by weight.

Examples of the method for fixing the crosslinked polydioxolane to the substrate include a method in which polydioxolane or an aqueous solution thereof is adhered to the substrate and then the polydioxolane is crosslinked, or heat-bonding the crosslinked polydioxolane or an adhesive agent. There may be mentioned a method of fixing them by. Preferred is a method in which polydioxolane or a solution thereof is attached to a substrate and then crosslinked. That is, in the case of crosslinking by irradiation with active energy, it is carried out by attaching an aqueous solution of polydioxolane to a substrate and then irradiating with active energy. When a cross-linking agent is added for cross-linking, a solution of polydioxolane is mixed with a predetermined amount of the cross-linking agent, the resulting composition is attached to a substrate, and then heated to a predetermined temperature. Done.

As a result, the crosslinked polydioxolane is fixed to the base material without impairing the water absorption property, and the adhesion between the base material and the polydioxolane becomes good. Further, if they are fixed without using an adhesive or the like, a liquid-absorbent composite having excellent safety is obtained. Examples of the method for attaching the polydioxolane to the substrate include a melting method in which the polydioxolane is melted by heat and attached, and a solution method in which the polydioxolane is dissolved in a solvent or water and attached. Further, in order to improve the adhesion between the base material and polydioxolane, a surfactant or an anchor coating agent can be applied to the base material. Further, the base material may be subjected to corona discharge treatment. By this method, the crosslinked polydioxolane can be fixed to the substrate without using a binder such as an adhesive. Further, since the base material is coated with the aqueous solution of polydioxolane and then irradiated with the active energy irradiation ray, the adhesion between the base material and the polydioxolane is further improved. Since the polydioxolane is cross-linked in the state of an aqueous solution by irradiation with active energy radiation, a liquid-absorbent resin composite having excellent water-absorbing properties is obtained.

The liquid-absorbent resin composite thus obtained is a base material having a low water-absorbing property, which has been imparted with water-absorbing property.
Further, the water-absorbent resin composite in which the crosslinked polydioxolane is adhered to the fibrous base material or the film-shaped base material is provided with strength when the strength of the film or sheet of the crosslinked polydioxolane alone is insufficient. Becomes Such a composite can be suitably used for a waterproof material for cables, a drip absorbing sheet, a freshness maintaining sheet, and the like. Further, since the crosslinked polydioxolane is fixed to the base material, processing and handling are improved.

In the present invention, various additives can be added to the liquid-absorbent resin or the liquid-absorbent resin composite according to the purpose and application. Additives can be added in advance when the polydioxolane is crosslinked. Further, they can be added to or mixed with the polydioxolane after cross-linking or the liquid-absorbent resin composite. As additives, silica fine particles, titanium oxide, zinc oxide, magnesium oxide, calcium carbonate, talc,
Inorganic fine particles represented by diatomaceous earth, iron powder, organic fine particles, filler, sorbitan fatty ester, sucrose fatty acid ester, polyoxyalkylene alkyl ether, surfactant represented by polyoxyalkylene acyl ester, tetrachloroiso Antifungal agents and antibacterial agents represented by phthalonitrile, thiabendazole, zinc pyrithione, etc., deodorants, glycerin, polyethylene glycol,
Plasticizers represented by dioctyl phthalate, guanidine sulfamate and its derivatives, guanidine phosphate and its derivatives, flame retardants represented by phosphate esters such as triethyl phosphate and trischloroethyl phosphate, lithium chloride and magnesium chloride. Absorbents represented by deliquescent inorganic salts such as calcium chloride and calcium lactate, synthetic polymers such as hydroxyethyl cellulose, carboxymethyl cellulose, polyvinyl alcohol, polyacrylates, various pharmaceuticals, agricultural chemicals, fertilizers, colorants, pulp , Activated carbon, gas adsorbents and the like. The addition amount of these additives is not particularly limited, but generally 0.0001 to 1000 per 1 part by weight of polydioxolane.
It is in the range of parts by weight, preferably 0.001 to 10 parts by weight.

The liquid-absorbent resin of the present invention thus obtained has the following features.

1. Since polydioxolane is cross-linked, the water absorption capacity of polyacrylic acid salt-based water-absorbing polymer decreases due to the effect of salt concentration in the solution and the effect of polyvalent metal, whereas the water absorption capacity does not decrease and salt resistance It has excellent water absorption performance.

2. It can absorb not only aqueous liquids but also organic solvents such as chloroform. 3. Since it has a good film-forming property and flexibility, it can be used as a water-absorbent film or sheet having good handleability and processability.

4. Processing by heat fusion or heat sealing can be easily performed.

5. It has good compatibility with other thermoplastic resins and can be easily kneaded with other thermoplastic resins to impart water absorption and antistatic performance.

6. The hydrogel has good gel strength and excellent transparency.

7. It has a cloud point and reversibly changes the gel transmittance, and repeats water absorption-water separation.

The liquid-absorbent composite of the present invention has the following features.

1. Since the crosslinked polydioxolane is fixed to the substrate, it is possible to impart water absorption and antistatic performance to the substrate having low water absorption.

2. Since the crosslinked polydioxolane is fixed to the base material, the strength is improved as compared with polydioxolane alone. In addition, the handleability and workability are further improved.

3. Compared with a base material to which a polyacrylic acid salt is fixed, it is excellent in flexibility and flexibility, and is easy to handle and feel.

The method for producing a liquid-absorbent resin of the present invention has the following features.

1. The polydioxolane before cross-linking can be molded into a desired shape and then cross-linked, and liquid-absorbent resins of various shapes can be easily obtained.

2. By cross-linking an aqueous solution of polydioxolane with irradiation of active energy, it is possible to obtain a liquid absorbing resin having excellent water absorption.

The method for producing a water absorbent resin composite of the present invention has the following features.

1. Since the polydioxolane is crosslinked after the polydioxolane is attached to the base material, the water absorption property of the polydioxolane is not hindered, and the crosslinked polydioxolane is prevented from falling off during water absorption.

Therefore, the liquid-absorbent resin and the liquid-absorbent resin composite of the present invention have the above-mentioned characteristics, and therefore, not only sanitary materials such as paper diapers, napkins and bandages, but also freshness retention of foods, drip absorption, packaging materials, Anti-condensation material, water blocking material for electric wires and communication cables, sealing material, cold insulating material, concrete admixture / modifying agent, cement breathing water absorption, agricultural / horticultural water retaining material, Cairo water retaining material, oil dehydration material, battery separator It can be used for various applications such as shoe insoles, deodorants, fragrances, artificial snow, soundproofing materials, vibration damping materials, artificial crystalline lenses, solid electrolytes and medical electrodes.

[0057]

The present invention will be further described below with reference to examples, but the present invention is not limited to these examples.

Reference Example 1 A four-necked flask equipped with a stirrer, a thermometer, a nitrogen introducing tube and a cooling tube was purged with nitrogen to obtain 60 g of 1,3-dioxolane.
Was introduced and the system was kept at 0 ° C. Next, 0.3 ml of a 5% phosphotungstic acid / acetone solution was added with stirring under a nitrogen atmosphere to initiate polymerization. After the heat generated by the polymerization reached a peak, 1 ml of triethylamine was added to stop the reaction.

The obtained dioxolane solution of polydioxolane was dried in a vacuum dryer at 100 ° C. for 5 hours to obtain polydioxolane (1).

The polystyrene equivalent number average molecular weight of the obtained polydioxolane (1) was 100,000.

Example 1 Polydioxolane (1) obtained in Reference Example 1 was dissolved in water at 60 ° C. to obtain a 5 wt% aqueous solution of polydioxolane. This was placed in a glass container and irradiated with gamma rays at 2.5 Mrad to obtain a liquid absorbing resin (1) in which polydioxolane was crosslinked and gelled.

Example 2 A liquid absorbing resin (2) of the present invention was obtained in the same manner as in Example 1 except that a 2% by weight aqueous solution of polydioxolane was used in Example 1.

Example 3 A liquid absorbing resin (3) of the present invention was obtained in the same manner as in Example 1 except that a 20% by weight aqueous solution of polydioxolane was used in Example 1.

Example 4 A liquid-absorbent resin (4) of the present invention was obtained in the same manner as in Example 1 except that gamma rays were irradiated at 10 Mrad in Example 1.

Example 5 0.1 g of the liquid-absorbent resins (1) to (4) obtained in Examples 1 to 4
Each (in terms of solid content) was immersed in a beaker containing 150 ml of pure water and slowly stirred with a magnetic stirrer. After 24 hours, the swollen liquid-absorbent resin was filtered through a wire net, drained sufficiently, and the weight of the swollen resin was measured, and the water absorption capacity (g / g) was determined according to the following formula. The results are shown in Table 1.

Water absorption capacity (g / g) = weight of swollen resin / (weight of solid content of liquid-absorbent resin) Example 6 Liquid-absorbent resins (1) to (4) obtained in Examples 1 to 4. ) To 0.9
Example 5 except that it was dipped in an aqueous solution of sodium chloride at wt%
The water absorption capacity was determined in the same manner as in. The results are shown in Table 1.

Example 7 The water absorption capacity was determined in the same manner as in Example 5 except that the liquid absorbing resins (1) to (4) obtained in Examples 1 to 4 were immersed in artificial seawater. The results are shown in Table 1.

Example 8 The liquid absorbing resins (1) to (4) obtained in Examples 1 to 4 were mixed with 0.0
The water absorption ratio was determined in the same manner as in Example 5 except that the film was immersed in a 5 wt% calcium chloride aqueous solution. The results are shown in Table 1.

Comparative Example 1 0.1 mol% of methylenebisacrylamide (relative to monomer) was added to a partially neutralized sodium acrylate aqueous solution (monomer concentration: 37% by weight) of which 75% was neutralized with sodium hydroxide.
Then, 0.5 g / mol of sodium persulfate was dissolved and oxygen in the solution was degassed with nitrogen.

This aqueous monomer solution was dropped on a steel belt heated to 120 ° C. to polymerize the monomer. The resin after polymerization was scraped off from the belt, dried, and then pulverized to obtain a comparative liquid absorbent resin (1). The water absorption capacity of each solution was determined in the same manner as in Examples 5-8. The results are shown in Table 1.

As is clear from the results shown in Table 1, the water-absorbing resin made of a conventional crosslinked sodium polyacrylate has a large water absorption capacity due to the influence of metal ions, and particularly polyvalent metal ions such as calcium. In the presence of metal ions, the liquid-absorbent resin of the present invention hardly absorbs in the presence of metal ions, but the water-absorption capacity of the resin does not change even in the presence of metal ions, and has excellent water-absorbing properties.

Example 9 The aqueous solution of polydioxolane of Example 1 was applied on a PET film to a thickness of 100 μm, and an electron beam was irradiated at 6 krad at an acceleration voltage of 250 kV in a nitrogen atmosphere. After irradiation, it was dried to obtain the liquid absorbing resin (5) of the present invention. It was flexible and could be folded.

This was immersed in pure water, 0.9% by weight sodium chloride aqueous solution, artificial seawater, and 0.05% by weight calcium chloride aqueous solution for 24 hours, and the resin after swelling was peeled off from the film of Example 5. The water absorption capacity (g / g) in each solution was determined in the same manner as in. The results are shown in Table 1.

Example 10 Sodium chloride was added to the aqueous solution of polydioxolane of Example 1 in an amount of 10% by weight based on polydioxolane. This product was irradiated with gamma rays in the same manner as in Example 1 to obtain the liquid-absorbent resin (6) of the present invention.

The water absorption capacity (g / g) of this product was determined as in Example 9.
Was similarly obtained. The results are shown in Table 1.

This product could be suitably used as a medical electrode.

Example 11 The aqueous solution of polydioxolane of Example 3 was placed on a release paper in an amount of 10
Coating with a thickness of 0 μm, accelerating voltage 250 under nitrogen atmosphere
The electron beam was irradiated with 6 Mrad at kV. After irradiation, it was dried and peeled from the release paper to obtain the liquid absorbing resin (7) of the present invention. This was a flexible, water-absorbent film that could be folded and stretched.

The water absorption capacity (g / g) of this product was determined as in Example 5.
It was determined in the same manner as ~ 9. The results are shown in Table 1.

Example 12 The liquid absorbing resin (1) obtained in Example 1 was dried under reduced pressure at 55 ° C. The absorption capacity (g / g) of chloroform was determined in the same manner as in Example 5 except that 0.1 g of the dried liquid-absorbent resin (1) was immersed in 150 g of chloroform. The absorption capacity of this product was 50 (g / g). Comparative absorbent resin (1)
When the absorption capacity of chloroform was measured in the same manner as above, it was not absorbed at all.

Example 13 The absorbent resin (1) obtained in Example 1 was dried under reduced pressure at 50 ° C. and then swollen in a heavy chloroform solution. When ¹ H-NMR of this product was measured at 25 ° C., singlet signals were detected at 3.7 ppm and 4.7 ppm as shown in FIG. 1, and the integration ratio was 2: 1. These were identified as protons of ethylene and methylene groups, respectively. For the measurement, VXR-30, a nuclear magnetic resonance measuring device manufactured by Varian Instruments Limited.
It was performed at 0S (300 MHz).

Further, the infrared absorption of the dried liquid-absorbent resin (1) was measured, and as shown in FIG.
Absorption peculiar to the ether bond appeared at around 200 cm ^-1 . Infrared spectrophotometer FTS-7 manufactured by Bio-Rad Co., Ltd.
Was performed using.

From the above results, it was revealed that the liquid absorbent resin (1) obtained in Example 1 was a liquid absorbent resin having a repeating unit of oxymethylene-oxyethylene.

Example 14 30 g of chloroform and the polydioxolane (1) obtained in Reference Example 1 were placed in a four-necked separable flask equipped with a stirrer, a thermometer, a nitrogen introducing tube and a cooling tube. Tolylene diisocyanate (0.14 g) and dibutyltin oxide (0.024 g) were added thereto, and the liquid-absorbent resin (8) of the present invention was obtained by stirring for 60 minutes.

Water absorption capacity of this product in each solution (g /
g) was determined. The results are shown in Table 1.

Example 15 The polydioxolane aqueous solution of Example 1 had a basis weight of 40 g / m ^2.
The polypropylene non-woven fabric of was squeezed after being dipped. This product was irradiated with 2.5 Mrad of gamma rays to obtain a liquid-absorbent resin composite (1) of the present invention. The amount of polydioxolane fixed was 40 g / m ² .

This product was cut into a piece of 5 cm × 5 cm, dipped in pure water / 0.9 wt% physiological saline / artificial seawater / 0.05 wt% calcium chloride aqueous solution for 24 hours and then suction-filtered to measure the weight. The water absorption ratio was determined by dividing by the weight of the composite before immersion. The results are shown in Table 1. This product was useful as a battery separator and a waterproof tape for cables.

Example 16 When the swollen gel of the absorbent resin (1) in Example 5 was immersed in warm water at 75 ° C., the swollen absorbent resin (1) became white and separated. The water absorption capacity of this product was 20 (g / g). When this product was immersed in warm water at 60 ° C., it immediately became a transparent gel.

[0088]

[Table 1]

[0089]

The liquid-absorbent resin of the present invention has a water-absorbing property that is not easily influenced by metal ions and has excellent salt resistance. Further, it can be handled as a sheet or film which has good film-forming properties and flexibility and is easy to handle and process. Further, processing by heat sealing or heat fusion is easy. Further, the liquid-absorbent resin composite in which the crosslinked polydioxolane is adhered to the substrate is
The handleability and workability are further improved. According to the production method of the present invention, such a liquid absorbing polymer or liquid absorbing resin composite can be easily obtained.

[Brief description of drawings]

FIG. 1 is an NMR chart of an example of a liquid-absorbent resin according to the present invention.

FIG. 2 is an infrared absorption spectrum diagram of an example of the liquid-absorbent resin according to the present invention.

Claims (11)

[Claims] 1. A liquid-absorbent resin comprising crosslinked polydioxolane. 2. A liquid-absorbent resin comprising a crosslinked polymer having an oxymethylene-oxyethylene repeating unit represented by the following chemical formula (I) and having a crosslinked structure. Embedded image 3. A method for producing a liquid-absorbent resin, which comprises cross-linking polydioxolane. 4. The method for producing a liquid-absorbent resin according to claim 3, wherein the cross-linking of polydioxolane is performed by irradiating an aqueous solution of polydioxolane with active energy irradiation rays. 5. Crosslinking of polydioxolane is carried out by blending a crosslinking agent having a polyfunctional reactive group capable of reacting with a hydroxyl group in the polydioxolane molecule and heating the mixture. Liquid resin manufacturing method. 6. A liquid-absorbent resin composite comprising a crosslinked polydioxolane fixed to a substrate. 7. The liquid-absorbent resin composite according to claim 6, wherein the substrate is a fibrous, sponge-like, film-like or porous substrate. 8. A method for producing a liquid-absorbent resin composite, comprising depositing polydioxolane on a substrate and then crosslinking the polydioxolane. 9. The production of the liquid-absorbent resin composite according to claim 8, wherein the polydioxolane is crosslinked by applying an aqueous solution of the polydioxolane to a substrate and then irradiating with active energy irradiation rays. Method. 10. Crosslinking of polydioxolane is carried out by adhering to the substrate a composition comprising a crosslinking agent having a polyfunctional reactive group capable of reacting with the hydroxyl groups in the polydioxolane molecule, and then heating. Claim 8 carried out by
The method for producing the liquid-absorbent resin composite according to item 1. 11. The method for producing a liquid-absorbent resin composite according to claim 8, wherein the substrate is a fibrous, sponge-like, film-like or porous substrate.