JP2001002703A - Self-crosslinked alkylcellulose derivative, and its production - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject derivative which has excellent biodegradability and further has excellent water absorbability, by irradiating a mixture comprising an alkylcellulose derivative and water with radiations. SOLUTION: This method for producing a self-crosslinked alkylcellulose derivative comprises irradiating a mixture comprising (A) 100 pts.wt. of an alkylcellulose derivative as a raw material (the alkyl group has one to three carbon atoms and may be substituted by one or more hydroxyl groups, or the like) and (B) 5 to 2,000 pts.wt. of water with radiations. The component A is preferably a carboxyalkylcellulose, a hydroxyalkylcellulose, an alkylcellulose or their mixture, which has at least one hydroxyl group or carboxyl group per glucose unit. 20% or more of the total amount of the hydroxyl groups and carboxyl groups of the component A is especially preferably their alkali metal salts, ammonium salts or amine salts.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a process for producing a self-crosslinked alkylcellulose derivative obtained by irradiating a mixture of an alkylcellulose derivative and water with radiation, or a self-crosslinked alkylcellulose derivative having biodegradability. The present invention relates to a method and a novel self-crosslinked alkylcellulose derivative obtained by the method.

[0002]

2. Description of the Related Art Conventionally, carboxymethylcellulose (C
MC) or a salt thereof is an aqueous composition such as a paint, an adhesive, a coating agent, a poultice, a soft cream, a soil modifying agent in the civil engineering field, a soil improving agent in the agricultural and horticultural field, a water retention agent, a coating agent, etc. Has been used as JP-A-10-324701 discloses a carboxy polysaccharide in which hyaluronic acid, alginic acid, CMC, or the like is chemically or intramolecularly self-crosslinked (crosslinking without using a crosslinking agent). . In this method, self-crosslinking is generated by dehydrating a carboxyl group and a hydroxyl group of a carboxypolysaccharide in a molecule or between molecules in the presence of a catalyst to form an ester bond. However, this method is not a crosslinking by radiation, but requires complicated preparation of raw materials or a dehydration catalyst. JP-A-8-89796 and JP-A-8-1969
No. 01 discloses a water-absorbing resin in which carboxyalkyl cellulose, carboxyalkyl starch and the like are chemically crosslinked with amino acids. However, this method is not a crosslinking by radiation, but requires complicated preparation of raw materials and requires an expensive crosslinking agent.
In general, a water-soluble polymer is cross-linked by a cross-linking agent, radiation, or the like, and is used as a highly water-absorbent resin or a gel (hereinafter simply referred to as a gel). In particular, acrylic acids are used as absorbents for disposable diapers and the like. However, polyacrylic acid has little biodegradability and causes a problem when discarded. Also, when used outdoors, such as in the civil engineering field,
Biodegradability of the water-absorbent resin or gel after use is required. On the other hand, CMC, which is a water-soluble polymer, is known to exhibit biodegradability by enzymes such as cellulase.
Irradiation of the MC alone causes the decomposition of the CMC to occur preferentially, so that there was a problem that effective cross-linking did not occur. Japanese Patent Publication No. 47-17965 discloses that a crosslinked product is obtained by reacting CMC with epichlorohydrin, but it has low water absorption and has a problem in safety.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is to provide a method for producing a self-crosslinked alkylcellulose derivative by irradiation, a self-crosslinked alkylcellulose derivative obtained by the method, and a biodegradable compound. It is an object of the present invention to provide a self-crosslinked alkylcellulose derivative of the above, and a self-crosslinked alkylcellulose derivative excellent in water absorption.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to achieve the above object, and as a result, by irradiating an aqueous solution of an alkyl cellulose derivative such as CMC with radiation, a self-crosslinking alkyl The present inventors have found that a cellulose derivative can be produced, and have completed the present invention to be able to obtain a biodegradable substance or a highly water-absorbing substance, and further a biodegradable and highly water-absorbing substance depending on a raw material, irradiation conditions, and the like. .

That is, a first aspect of the present invention is to provide a raw material alkylcellulose derivative (alkyl having 1 to 3 carbon atoms;
Alkyl may be substituted by a hydroxy group or a carboxyl group. And b) irradiating a mixture comprising 100 parts by weight and 5 to 2,000 parts by weight of water with radiation. A second aspect of the present invention is that the raw material alkylcellulose derivative is carboxyalkylcellulose, hydroxyalkylcellulose, alkylcellulose having at least one hydroxy group or carboxyl group per glucose unit, or a mixture thereof. The present invention provides a method for producing a self-crosslinkable alkyl cellulose derivative according to the first aspect. A third aspect of the present invention is the first aspect, wherein at least 20% of the total of the hydroxyl groups and the carboxyl groups of the starting alkyl cellulose derivative is an alkali metal salt, an ammonium salt or an amine salt.
And a method for producing the self-crosslinked alkylcellulose derivative described in (1). A fourth aspect of the present invention is the self-crosslinking according to the first aspect of the present invention, wherein the raw material alkyl cellulose derivative has an average degree of polymerization of 10 to 2,000 and an average degree of etherification of 0.5 or more. A method for producing a type alkyl cellulose derivative is provided. A fifth aspect of the present invention provides the method for producing a self-crosslinkable alkylcellulose derivative according to the first aspect, wherein the gel fraction is 0.1% or more. A sixth aspect of the present invention is the first aspect of the present invention, wherein the irradiation amount of radiation is 0.1 kGy or more in terms of γ-ray.
And a method for producing the self-crosslinked alkylcellulose derivative described in (1). A seventh aspect of the present invention provides the method for producing a self-crosslinkable alkylcellulose derivative according to any one of the first to sixth aspects of the present invention, wherein the product is further dried. An eighth aspect of the present invention provides a self-crosslinkable alkylcellulose derivative obtained by the production method according to any one of the first to seventh aspects of the present invention. A ninth aspect of the present invention is that 0.2 g of a dry product of a self-crosslinking alkylcellulose derivative is added to an aqueous acetic acid solution (pH 4.5) containing 0.5% by weight of cellulase.
(8) The self-crosslinkable alkylcellulose derivative according to the eighth of the present invention, wherein the biodegradation rate after standing for 8 hours in addition to 10 ml of the buffer solution is 50% or more. A tenth aspect of the present invention provides the self-cross-linked alkylcellulose derivative according to the eighth aspect of the present invention, wherein the water absorption when using distilled water is at least 30 times the weight of its own weight. An eleventh aspect of the present invention provides the self-crosslinked alkylcellulose derivative according to the eighth aspect of the present invention, wherein the gel in the obtained state has a crushing strength of 100 g / cm ² or more.

[0006]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, an alkylcellulose derivative used as a raw material is carboxyalkylcellulose (A), hydroxyalkylcellulose (B), alkylcellulose (C), or a mixture thereof, and these are glucose. It has at least one hydroxy or carboxyl group per unit.

Carboxyalkylcellulose (A) In the present invention, carboxyalkylcellulose (A) used as a raw material is obtained by replacing the hydrogen of the hydroxyl group of cellulose with a carboxymethyl, carboxyethyl or carboxypropyl group. Preferred and preferred carboxyalkyl celluloses (A) are carboxymethyl cellulose and carboxyethyl cellulose. In the carboxyalkyl cellulose, 20% or more, preferably 40% or more of the carboxyl groups are alkali metal salts, ammonium salts or amine salts. Examples of the alkali metal salt include a sodium salt, a potassium salt, a lithium salt and the like, and a sodium salt is preferable. If the salt formation ratio is less than the above range, it is difficult to form a uniform mixture or aqueous solution with water. There is no particular upper limit on the ratio of salt formation, and a 100% salt may be formed.

Hydroxyalkylcellulose (B) In the present invention, hydroxyalkylcellulose (B) used as a raw material is obtained by reacting hydrogen of a hydroxyl group of cellulose with, for example, ethylene oxide or propylene oxide. group hydroxyethyl be replaced with hydrogen (-C ₂ H ₄ OH) group, hydroxy isopropyl (-C ₃ H ₆ OH), hydroxy -n
- propyl group (-C ₃ H ₆ OH), more further ethylene oxide to the hydroxy-terminated polyoxyalkylene ethers substituent obtained by propylene oxide or the like is 1 to 10 molecular reactions. The hydroxyalkyl cellulose (B) is preferably hydroxyethyl cellulose or hydroxypropyl cellulose. In the hydroxyalkyl cellulose (B), at least 20%, preferably at least 40%, more preferably at least 50% of the hydroxyl groups are alkali metal salts. Examples of the alkali metal salt include a sodium salt, a potassium salt, a lithium salt and the like, and a sodium salt is preferable. If the salt formation ratio is less than the above range, it is difficult to form a uniform mixture or aqueous solution with water. There is no particular upper limit on the ratio of salt formation, and a 100% salt may be formed.

Alkyl Cellulose (C) In the present invention, the alkyl cellulose (C) used as a raw material is one in which the hydrogen of the hydroxyl group of cellulose is partially substituted by a methyl group, an ethyl group or a propyl group, and is preferable. Alkyl cellulose (C) is methyl cellulose. The alkyl cellulose has a degree of alkyl etherification of 66% or less, preferably 50%.
Or less, more preferably 33% or less. Alkyl cellulose (C) used as a raw material has at least 40%, preferably at least 50%, of the remaining hydroxyl groups are alkali metal salts. Examples of the alkali metal salt include a sodium salt, a potassium salt, a lithium salt and the like, and a sodium salt is preferable. If the salt formation ratio is less than the above range, it is difficult to form a uniform mixture or aqueous solution with water. There is no particular upper limit for the ratio of salt formation, and 100%
Salts may be formed.

The above-mentioned alkyl cellulose derivatives are not particularly limited in average degree of polymerization, but practically, for example, 10 to 2,
000, preferably 50 to 1,000, more preferably about 200 to 800.

The average degree of etherification of an alkylcellulose derivative (the degree of substitution of hydrogen of a hydroxyl group of cellulose with the carboxyalkyl group, hydroxyalkyl group or alkyl group) is, for example, 0.1. 5 or more, preferably 0.8 or more, more preferably 1.1 or more, and at most 3. When the average degree of etherification is less than 0.5, sufficient crosslinking does not occur.

The alkylcellulose derivative used as a raw material in the present invention is produced by a known method,
In particular, commercially available products can be used.

For example, carboxyalkyl cellulose is produced by various methods such as a conventional slurry method (high liquid magnification method) and a kneader method (low liquid magnification method), for example, by reacting cellulose with an alkali to produce alkali cellulose. A step (mercerization step or arsellation step) and a step of reacting alkali cellulose with monochloroacetic acid to produce carboxyethylcellulose by hydrolysis of the ester after reaction with carboxymethylcellulose or acrylate (carboxyalkylation step)
And can be manufactured by the method constituted by

For example, hydroxyalkyl cellulose is obtained by reacting a hydroxyl group of cellulose with an alkylene oxide, hydroxyethyl cellulose is obtained by reacting ethylene oxide, and hydroxypropyl cellulose is obtained by reacting propylene oxide. Those further reacted with an alkylene oxide can also be used. For example, ethyl hydroxyethyl cellulose is obtained by further reacting ethylene oxide with hydroxyethyl cellulose.

For example, alkyl cellulose can be produced by reacting the above-mentioned alkali cellulose with alkyl chloride or dialkyl sulfate. For example, methyl cellulose is produced by reacting alkali cellulose with methyl chloride or dimethyl sulfate, and ethyl cellulose is produced by reacting alkali cellulose with ethyl chloride or diethyl sulfate.

Various materials such as wood pulp and linter pulp can be used as cellulose. As the alkali, the above-mentioned alkali metals (such as lithium, potassium, and sodium), ammonia, and amine can be used. Usually, sodium is used and usually used as a hydroxide or an aqueous solution. In the mercerization process,
The amount of alkali (such as sodium hydroxide) used is usually
It can be selected from a range of about 30 to 80 parts by weight, preferably about 40 to 75 parts by weight based on 100 parts by weight of cellulose.
In the slurry method, the amount of alkali (such as sodium hydroxide) used is usually 35 to 70 parts by weight, preferably about 45 to 65 parts by weight, based on 100 parts by weight of cellulose. In the slurry method, the cellulose concentration is about 1 to 7% by weight, and in the kneader method, the cellulose concentration is 10 to 25%.
Mercerization is often performed at about weight%. The alkali concentration in the mercerization step varies depending on the slurry method, the kneader method, etc.
It can be carried out in an aqueous medium of about 0% by weight, and in the kneader method, it can be usually carried out in an aqueous medium having a concentration of about 2 to 15% by weight. The mercerization step may be performed in the presence of a suitable solvent. Examples of the solvent include water, alcohols (ethanol, isopropanol, etc.), ketones (acetone), and cellosolves (methyl cellosolve,
Ethyl cellosolve, etc.). The carboxyalkylcellulose generated in this way is dewatered,
It can be purified by washing and drying. If necessary, after the completion of the reaction, it may be treated with a peroxide such as hydrogen peroxide or peracetic acid to adjust the viscosity.

In the present invention, when the radiation is applied, the mixing ratio of the raw material alkylcellulose derivative and water is 5 to 2,000 to 100 parts by weight of the alkylcellulose derivative.
00 parts by weight. As described above, a raw material alkylcellulose derivative such as CMC is preferentially decomposed by radiation, but in the presence of water, a hydroxyl radical generated from water is generated, and it is considered that self-crosslinking proceeds through this radical. The mixed state of the alkylcellulose derivative and water may be a state in which the alkylcellulose derivative is contained as water, a paste, or an aqueous solution, but a state as uniform as possible is preferable. If the amount of water is less than the above range, the decomposition of the raw material alkylcellulose derivative increases, and if the amount is more than the above range, cross-linking hardly occurs.

The water used in the present invention includes city water, industrial water, degassed water, deionized water, gel filtered water, distilled water, and the like, and preferably those containing no oxygen or ions. It is.

The radiation source used in the radiation irradiation treatment according to the present invention includes α-rays, β-rays, γ-rays, X-rays, electron beams,
Ultraviolet rays or the like can be used, but γ-rays, electron beams, and X-rays from cobalt 60 are more preferable. Among them, the γ-rays or electron beam irradiation treatment using an electron accelerator is convenient for introducing a bridge structure. .

In the present invention, the amount of radiation to be irradiated is
It differs between the case where a water-absorbent resin is intended and the case where a high-strength gelled product is obtained, and also depends on the mixing ratio between the raw material alkylcellulose derivative and water. When the purpose is a water-absorbent resin, the irradiation amount of radiation is 0.1 to 5 in terms of γ-ray.
0 kGy, preferably 0.3 to 20 kGy, more preferably 0.5 to 10 kGy. If the radiation dose is less than the above range, crosslinking does not occur and water absorption becomes insufficient. If the radiation irradiation amount exceeds the above range, crosslinking proceeds too much and water absorption becomes insufficient. When aiming for a high-strength gelled product,
The irradiation amount of radiation is 20 to 300 kGy in terms of γ-ray,
Preferably it is 30 to 200 kGy, more preferably 50 to 100 kGy. If the radiation dose is less than the above range, the strength of the gel, particularly the crushing strength, becomes weak, and if it exceeds the above range, it becomes uneconomical.

In the irradiation, when the irradiation is performed in the absence of oxygen, crosslinking can be performed efficiently (ie, at a low radiation dose). When irradiated in the presence of oxygen,
This is because the ratio of the oxidative decomposition of the alkyl cellulose derivative increases.

The gel fraction of the self-cross-linked alkylcellulose derivative obtained as described above may be 0.1 to 50%, preferably 0.5 to 50% for the purpose of a water-absorbing resin.
It is 40%, more preferably 1 to 30%. If the gel fraction of the obtained self-crosslinking alkylcellulose derivative is less than the above range, crosslinking will be insufficient, and if it exceeds the range, crosslinking will proceed too much and water absorption will be insufficient. When a high-strength gelled product is intended, the gel fraction of the self-crosslinking alkylcellulose derivative is 30% or more, preferably 50% or more, more preferably 60% or more, and at most 100%.
It is. If the gel fraction of the self-crosslinking alkyl cellulose derivative is less than the above range, the gel strength will be insufficient.

The gel fraction is the ratio of insoluble components when the product is immersed in a large amount (for example, 10 to 100 times the product) of distilled water for 48 hours and then filtered through a 20-mesh stainless steel wire mesh. Is obtained by the following equation. Gel fraction (%) = (W ₂ / W ₁ ) × 100 (where W ₁ represents the dry weight of the starting alkylcellulose derivative used, and W ₂ represents the dryness of the insoluble matter after filtration of the crosslinked product after the filtration. Represents weight.)

The biodegradability of the self-crosslinked alkylcellulose derivative obtained as described above is measured as follows. 0.2 g of the dried product after the irradiation treatment was used for the enzyme cellulase 0.5 used for biodegradability.
In addition to 10 ml of an aqueous acetic acid solution (buffer of pH 4.5) containing 10% by weight, biodegradation was carried out at 40 ° C for 0 to 8 hours under standing, and the elapsed time and the residual ratio of the remaining self-crosslinked alkylcellulose derivative Was measured. The biodegradation rate is 100% -residual rate%. When the purpose is a water-absorbing resin, the biodegradation rate in the above time is 50% or more, preferably 70%.
It is more preferably 80% or more. The number of hours until 100% decomposition is prepared by selecting the degree of etherification, the degree of crosslinking, and the like. When aiming for a high-strength gelled product,
The biodegradation rate in the above time is 40% or more, preferably 50% or more, and more preferably 60% or more. 10
The number of hours until 0% decomposition is prepared by selecting the degree of etherification, the degree of crosslinking, and the like.

In the present invention, the self-crosslinked alkylcellulose derivative after the irradiation treatment can be dried and used as a solid or powder. The drying conditions are not particularly limited, and a desired moisture content can be obtained by a known method using heating, reduced pressure, or the like.

The self-crosslinking type alkyl cellulose derivative of the present invention has properties such as water absorption, high gel strength, and / or biodegradability in addition to the characteristics of the alkyl cellulose derivative as a raw material. In addition to the conventional uses listed in the general literature and the literature described in the prior art, water absorption represented by disposable diapers and sanitary napkins in fields where higher performance is required for those uses. Can be used for conductive resins.

[0027]

EXAMPLES The present invention will now be described specifically with reference to examples, but the present invention is not limited to these examples. The raw material carboxyalkyl cellulose (manufactured by Daicel Chemical Industries, Ltd.) used is as follows. A: CMC viscosity of a 10% by weight aqueous solution at 20 ° C. 73 (m
Pa · s), average degree of etherification 1.27 B: CMC, viscosity at 20 ° C. 161 of 10% by weight aqueous solution
(MPa · s), average degree of etherification 2.21 C: CMC, viscosity of 10% by weight aqueous solution at 20 ° C. 168
(MPa · s), average degree of etherification 0.86 D: CMC, viscosity of 20% by weight aqueous solution at 20 ° C. 250
(MPa · s), average degree of etherification 1.29 E: CMC viscosity of a 10% by weight aqueous solution at 20 ° C. 3670
(MPa · s), average degree of etherification 1.22 F: CMC, viscosity at 20 ° C. of a 10% by weight aqueous solution 244
(MPa · s), average degree of etherification 1.32 G: carboxyethyl cellulose, viscosity at 20 ° C. of 10% by weight aqueous solution 200 (mPa · s), average degree of etherification 1.32 HPC1: hydroxypropylcellulose, 2% by weight 20 ° C. viscosity of aqueous solution at 150 ° C. 150 to 400 (mPa · s) HPC2: hydroxypropylcellulose 2% by weight aqueous solution at 20 ° C. of 1,000 to 4,000 (mPa · s)
s) MC5: Methyl cellulose, 20% viscosity of a 2% by weight aqueous solution at 20 ° C. 20 to 30 (mPa · s) MC6: Methyl cellulose, 2% by weight aqueous solution at 20 ° C. of 6,000 to 9,000 (mPa · s)

Example 1 γ-rays were irradiated to aqueous solutions of the raw material F having various concentrations. The concentrations were 5, 10, 20,
30% by weight. The results are shown in FIG. The horizontal axis in FIG.
The dose (Dose: unit kGy) is shown, and the vertical axis shows the gel fraction (% by weight) of CMC after irradiation.

Example 2 A 20% by weight aqueous solution of the above raw materials A to E was irradiated with γ-rays. The results are shown in FIG. The horizontal axis in FIG. 2 shows the dose (Dose: unit kGy), and the vertical axis shows the gel fraction (% by weight) of CMC after irradiation.

Example 3 γ-rays were irradiated to aqueous solutions of the raw material F having various concentrations. The concentrations were 5, 10, 20,
30% by weight. The irradiated CMC was dried. The water absorption of the dried product was measured. The results are shown in FIG. The horizontal axis of FIG. 3 shows the dose (Dose: unit kGy), and the vertical axis shows the absorbed water (g) per 1 g of the dried gel of CMC after irradiation.
Is shown.

Example 4 The concentration of the raw material F was 20 or 30.
A 20% by weight aqueous solution was irradiated with 20 kGy of gamma rays. The biodegradation rate of CMC after irradiation by cellulase is shown in FIG. FIG.
The horizontal axis indicates the biodegradability time (hour), and the vertical axis indicates CMC.
Shows the residual rate (%) of Biodegradation rate is 100%-Residual rate%
It is.

Example 5 A 20% by weight aqueous solution of the raw material G was irradiated with γ-rays. As in Example 1, the gel fraction increased as the dose increased.

Example 6 The above raw materials HPC1, HPC2,
A 30% by weight aqueous solution of MC5 or MC6 was irradiated with γ-rays at each dose. FIG. 5 shows the results. The horizontal axis in FIG. 5 shows the dose (Dose: unit kGy), and the vertical axis shows the gel fraction (% by weight) after irradiation. In HPC1 and HPC2, there is a peak at a dose of 10 to 40 kGy, and crosslinking is effectively performed. On the other hand, when MC6 is used, crosslinking occurs on the high dose side, and when MC5 has a low polymerization degree, crosslinking occurs on the higher dose side.

Example 7 A 40 wt% aqueous solution of the raw materials HPC1 and HPC2 was irradiated with γ-rays at various doses. FIG. 6 shows the results. The horizontal axis in FIG. 6 is the dose (Dose: unit k).
Gy), and the vertical axis indicates the gel fraction (% by weight) after irradiation. In this example, a 40% by weight aqueous solution has a higher degree of crosslinking than a 30% by weight aqueous solution.

[0035]

According to the present invention, a self-crosslinking type alkyl cellulose derivative can be obtained. Depending on the type of the raw material alkylcellulose derivative, the moisture ratio at the time of irradiation, and the irradiation dose, it is a water-absorbing resin or a high-strength gelled product, and depending on the conditions, a biodegradable product can be obtained.

[Brief description of the drawings]

FIG. 1 is a graph showing a relationship between an irradiation dose and a gel fraction in Example 1 of the present invention.

FIG. 2 is a graph showing a relationship between an irradiation dose and a gel fraction in Example 2 of the present invention.

FIG. 3 is a graph showing the relationship between the irradiation dose and the water absorption of a dried product in Example 3 of the present invention.

FIG. 4 is a graph showing the change over time in the biodegradation rate in Example 4 of the present invention.

FIG. 5 is a graph showing the relationship between irradiation dose and gel fraction in Example 6 of the present invention.

FIG. 6 is a graph showing the relationship between irradiation dose and gel fraction in Example 7 of the present invention.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme court ゛ (Reference) C09J 101/28 C09J 101/28 101/32 101/32 C08L 1:08 (72) Inventor Tamagawa Kume Gunma No. 1233 Watanuki-cho, Takasaki-shi, Japan Inside the Takasaki Research Laboratory, Japan Atomic Energy Research Institute (72) Inventor Tadashi Murakami 1-323 Shinmatsudo Minami, Matsudo-shi, Chiba F-term (reference) 4C090 AA05 BA28 BA29 BA30 BA31 BB05 BB12 BB52 BD03 BD05 BD12 BD13 CA23 CA35 DA22 DA29 4F070 AA02 AB02 AB03 AB17 GA04 GB06 4J038 BA091 GA03 GA06 MA12 MA14 NA07 NA27 PA17 4J040 BA081 BA091 GA05 GA07 LA01 LA07 LA11 PA32

Claims (11)

[Claims] 1. 100 parts by weight of a raw material alkylcellulose derivative (alkyl has 1 to 3 carbon atoms, and the alkyl may be substituted by a hydroxy group or a carboxyl group) and 5 to 2,000 parts by weight of water A method for producing a self-crosslinking alkylcellulose derivative, which comprises irradiating a mixture comprising: 2. A carboxyalkyl cellulose, wherein the raw material alkyl cellulose derivative has at least one hydroxy group or carboxyl group per glucose unit.
Hydroxyalkyl cellulose, alkyl cellulose,
2. The method for producing a self-crosslinkable alkylcellulose derivative according to claim 1, wherein the mixture is a mixture thereof. 3. The self-crosslinkable alkyl cellulose derivative according to claim 1, wherein at least 20% of the total of the hydroxyl groups and carboxyl groups of the starting alkyl cellulose derivative is an alkali metal salt, ammonium salt or amine salt. Production method. 4. The self-crosslinkable alkyl cellulose derivative according to claim 1, wherein the raw material alkyl cellulose derivative has an average degree of polymerization of 10 to 2,000 and an average degree of etherification of 0.5 or more. Production method. 5. The method for producing a self-crosslinkable alkyl cellulose derivative according to claim 1, wherein the gel fraction is 0.1% or more. 6. A radiation dose of 0.1 kGy in terms of γ-rays.
The method for producing a self-crosslinked alkylcellulose derivative according to claim 1, wherein 7. The method for producing a self-crosslinkable alkyl cellulose derivative according to claim 1, wherein the product is further dried. 8. A self-crosslinking alkylcellulose derivative obtained by the production method according to claim 1. 9. Addition of 0.2 g of a dry product of a self-crosslinking alkylcellulose derivative to 10 ml of an aqueous acetic acid solution (pH 4.5 buffer) containing 0.5% by weight of cellulase,
9. The self-crosslinkable alkylcellulose derivative according to claim 8, wherein the biodegradation rate after standing for a time is 50% or more. 10. The self-crosslinked alkylcellulose derivative according to claim 8, wherein the water absorption when using distilled water is 30 times or more by weight of its own weight. 11. The crushing strength of the gel in the obtained state is 10
Self-crosslinking alkylcellulose derivative according to claim 8, characterized in that at 0 g / cm ² or more.