Resin composition

Abstract

To provide a resin composition that has a reduced environmental load and is capable of forming a water-absorbing article by coating or impregnation.SOLUTION: There is provided a resin composition for coating or impregnation, which includes a glucose polymer having an introduced acidic group or a salt thereof, in starch or a partial degradation product thereof.SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a resin composition. [Background technology]

[0002] Water-absorbing resins are widely used in various fields such as sanitary products, food, agriculture and forestry, and civil engineering. As such water-absorbing resins, partially neutralized salts of polyacrylic acid and polymethacrylic acid are widely used, and water-absorbing resins made from polysaccharides such as starch are known. As for the form of use of water-absorbing resins, granular ones are widely used in paper diapers and napkins, and other types include those made into films and those impregnated into matrices such as nonwoven fabrics.

[0003] Patent Document 1 discloses that a water-soluble polymer such as polyvinyl alcohol is applied to a nonwoven fabric and then dried to produce a nonwoven fabric sheet capable of absorbing liquid. Patent Document 2 discloses that a coating composition containing a wax-based emulsion and a water-soluble resin such as polyvinyl alcohol is applied to paper and then dried to produce moisture-proof paper. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent Publication No. 2020-158934 [Patent Document 2] Japanese Patent Publication No. 5-156208 Summary of the Invention [Problem to be solved by the invention]

[0005] An object of the present invention is to provide a resin composition which has a small environmental impact and can be used to form water-absorbent articles by coating or impregnation. [Means for solving the problem]

[0006] The present inventors have discovered that a resin composition containing starch or a partial hydrolysis product thereof is a naturally derived material, has a small environmental impact, and can be suitably used for coating or impregnation, and have completed the present invention.

[0007] That is, the present invention includes the following aspects. <1> A resin composition for coating or impregnation, comprising a glucose polymer in which an acidic group or a salt thereof has been introduced into starch or a partially hydrolyzed product thereof.

[0008] <2> Item 2. The resin composition according to item 1, wherein the glucose polymer has an acidic group content of 0.05 to 1.8 meq / g.

[0009] <3> Item 3. The resin composition according to item 1 or 2, wherein the acidic group is a carboxyalkyl group, a carboxyalkenyl group, or a sulfoalkyl group.

[0010] <4> moreover, Water, or A mixed solvent consisting of water and a hydrophilic solvent, with the hydrophilic solvent content being 60% by volume or less. Item 3. The resin composition according to item 1 or 2, comprising:

[0011] <5> A substrate, and Item 3. A coating film made of the resin composition according to item 1 or 2, applied onto the substrate. A water-absorbent laminate comprising:

[0012] <6> A step of applying the resin composition according to item 1 or 2 onto a substrate; and A process of heating and drying the applied resin composition to form a water absorbing layer. Including, A method for producing a water-absorbent laminate.

[0013] <7> Item 3. A water-absorbing film comprising the resin composition according to item 1 or 2.

[0014] <8> A step of applying the resin composition according to item 1 or 2 onto a releasable substrate; and A process of heating and drying the applied resin composition to form a water absorbing layer. Including, A method for producing a water-absorbent film.

[0015] <9> Item 3. A water-absorbent article comprising a matrix and a water-absorbent resin comprising the resin composition according to item 1 or 2 present in the matrix.

[0016] <10> The matrix is ​​made of cellulose or resin. Item 10. The absorbent article according to item 9.

[0017] <11> A step of impregnating a matrix with the resin composition according to item 1 or 2; and A step of heating and drying the impregnated resin composition Including, A method for producing an absorbent article. Effect of the Invention

[0018] The resin composition of the present invention has a small environmental impact and can be used to form water-absorbent articles by coating or impregnation. Furthermore, water-absorbent resins made from starch contribute to carbon neutrality and can reduce the environmental impact. [Brief description of the drawings]

[0019] [Figure 1] 4 shows a test piece of the water-absorbent film of Example 5. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0020] <<Resin composition>> The resin composition of the present invention is characterized in that it contains a glucose polymer in which an acidic group or a salt thereof has been introduced into starch or a partial hydrolyzate thereof, and is for use in coating or impregnation.

[0021] <Starch> Starch has the advantages of being highly safe for the human body, having excellent water absorption, and having a small environmental impact when disposed of. The starch raw material used as the raw material for glucose polymers is not particularly limited, and examples thereof include tapioca starch, potato starch, corn starch such as waxy corn starch and high amylose starch, wheat starch, rice starch, and sweet potato starch.

[0022] The starch may be a derivative in which the hydrogen atom of the hydroxyl group of the glucose unit constituting the starch is replaced by a functional group (also called processed starch or modified starch) or bleached starch. The position of the hydroxyl group where the hydrogen atom is replaced may be any of the 1st, 2nd, 3rd, 4th, and 6th positions of the glucose unit, but the 2nd, 3rd, and 6th positions are preferred. Examples of the functional group include hydrocarbon groups such as methyl and ethyl groups; substituents having a hydroxyl group such as hydroxypropyl and hydroxyethyl groups; and substituents having a carboxyl group such as carboxymethyl groups. Examples of starch derivatives include acetylated adipate crosslinked starch, acetylated phosphate crosslinked starch, acetylated oxidized starch, sodium octenylsuccinate starch, starch acetate, oxidized starch, hydroxypropyl starch, hydroxypropyl phosphate crosslinked starch, phosphate monoesterified phosphate crosslinked starch, phosphated starch, phosphate crosslinked starch, cationic starch, urea phosphate esterified starch, etc. Also usable are methylethylated starch and hydroxypropylmethylated starch substituted with two or more functional groups.

[0023] <Partially hydrolyzed starch> As the raw material of the glucose polymer, a partial hydrolysis product of starch may be used. The partial hydrolysis product of starch is a product in which some of the glucosidic bonds of starch are decomposed, but the position where the decomposition occurs and the manner of decomposition are not limited. The resin composition may contain both starch and a partial hydrolysis product of starch. The weight-average molecular weight (Mw) of the partial hydrolysis product of starch is not particularly limited, but is preferably 7.5 million or less, more preferably 5 million or less, even more preferably 4.5 million or less, and even more preferably 4 million or less. The lower limit of the weight-average molecular weight of the partial hydrolysis product of starch is not particularly limited, but is preferably 50,000 or more, more preferably 100,000 or more, and even more preferably 200,000 or more. If the weight-average molecular weight is less than 50,000, the water absorption amount of the water-absorbent resin made of the resin composition tends to decrease. When the viscosity of starch affects the operability in production, it is also possible to use two or more types of starch and / or partial hydrolysis products of starch having different weight-average molecular weights, or other additives, in combination, depending on the application and cost. The weight average molecular weight can be determined by aqueous size exclusion chromatography based on a calibration curve of molecular weight and elution time prepared using pullulan of known molecular weight.

[0024] The degree of dispersion (weight average molecular weight (Mw) / number average molecular weight (Mn)) of the partial hydrolysis product of starch is not particularly limited, but is generally 5 or more, and preferably 7 or more. If the degree of dispersion is less than 5, the water absorption capacity of the water absorbent resin tends to decrease. There is no particular upper limit to the degree of dispersion. The number average molecular weight can be determined by aqueous size exclusion chromatography based on a calibration curve of molecular weight and elution time prepared using pullulan with a known molecular weight.

[0025] The method for producing the partial hydrolyzate of starch is not particularly limited, and examples thereof include methods of subjecting starch to enzyme treatment, acid treatment, physical crushing, etc. These methods may be combined. The enzyme treatment may be performed after gelatinization of starch, or may be performed simultaneously with gelatinization. As a method for performing the enzyme treatment after gelatinization of starch, a method may be used in which starch is first suspended in water and heated to gelatinize it, and then an enzyme is added to perform an enzyme reaction. As a method for performing the enzyme treatment simultaneously with starch gelatinization, a method may be used in which starch is suspended in water, and the mixture to which the enzyme is further added is heated within a temperature range in which the enzyme is not completely inactivated. Among these, it is preferable to perform the enzyme treatment while gelatinizing the starch by heating and kneading it at 70 to 110°C.

[0026] When partial decomposition of starch is carried out by enzyme treatment, the enzyme to be used is not particularly limited as long as it can decompose starch, and may be either an exo-type enzyme or an endo-type enzyme. Specific examples of the enzyme include α-amylase, amylomaltase, cyclomaltodextrin glucanotransferase, 4-α-glucanotransferase, 4,6-α-glucanotransferase, neopullulanase, and amylopullulanase. These enzymes may be used in combination. The pH during the enzyme treatment is not particularly limited, but a pH of 5.0 to 7.0 is preferred. The pH can be adjusted by adding hydrochloric acid, acetic acid, sodium hydroxide, potassium hydroxide, or the like.

[0027] When the partial decomposition of starch is carried out by acid treatment, the acid to be used is not particularly limited as long as it can decompose starch, and specific examples include hydrochloric acid, sulfuric acid, oxalic acid, acetic acid, formic acid, trifluoroacetic acid, etc. The temperature during the acid treatment is preferably 150 to 160° C. When the partial decomposition of starch is carried out by physical crushing, specific means include radiation irradiation, shearing, grinding, high-pressure treatment, ultrasonic waves, thermal decomposition, photolysis, and combinations thereof.

[0028] <Glucose polymer, acidic group> The term "glucose polymer" as used herein means a material in which an acidic group or a salt thereof has been introduced into starch or a partially hydrolyzed product thereof.

[0029] Examples of the acidic group include acidic groups having a carboxyl group, such as a carboxyalkyl group and a carboxyalkenyl group; acidic groups having a sulfo group, such as a sulfoalkyl group and a sulfoalkenyl group; and acidic groups having a phospho group, such as a phosphoalkyl group and a phosphoalkenyl group.

[0030] A carboxyalkyl group is an alkyl group substituted with a carboxyl group. The number of carbon atoms of the alkyl group substituted with a carboxyl group is preferably 1 to 8, more preferably 1 to 5. The alkyl group may be either linear or branched. Specific examples of the alkyl group include a methyl group, an ethyl group, an n-propyl group, an i-propyl group, an n-butyl group, an i-butyl group, an s-butyl group, a t-butyl group, an n-pentyl group, a 1-methyl-n-butyl group, a 2-methyl-n-butyl group, a 3-methyl-n-butyl group, a 1,1-dimethyl-n-propyl group, a 1,2-dimethyl-n-propyl group, a 2,2-dimethyl-n-propyl group, and a 1-ethyl-n-propyl group.

[0031] Specific examples of the carboxyalkyl group include a carboxymethyl group, a carboxyethyl group, a carboxypropyl group, a carboxybutyl group, and a carboxypentyl group.

[0032] A carboxyalkenyl group is an alkenyl group substituted with a carboxyl group. The number of carbon atoms of the alkenyl group substituted with a carboxyl group is preferably 2 to 8, more preferably 2 to 4. The alkenyl group may be either linear or branched. Specific examples of the alkenyl group include an ethenyl group, a 1-propenyl group, a 2-propenyl group, a 1-methyl-1-ethenyl group, a 1-butenyl group, a 2-butenyl group, a 3-butenyl group, a 2-methyl-1-propenyl group, a 2-methyl-2-propenyl group, a 1-ethylethenyl group, a 1-methyl-1-propenyl group, and a 1-methyl-2-propenyl group.

[0033] Specific examples of the carboxyalkenyl group include a carboxyethenyl group, a carboxypropenyl group, and a carboxybutenyl group.

[0034] The sulfoalkyl group is an alkyl group substituted with a sulfo group. Examples of the alkyl group substituted with a sulfo group include the alkyl groups mentioned in relation to the carboxyalkyl group. Specific examples of the sulfoalkyl group include a sulfomethyl group, a sulfoethyl group, and a sulfopropyl group.

[0035] The sulfoalkenyl group is an alkenyl group substituted with a sulfo group. The alkenyl group substituted with a sulfo group can be any of the alkenyl groups described above for the carboxyalkenyl group. Specific examples of the sulfoalkenyl group include a sulfoethenyl group and a sulfopropenyl group.

[0036] A phosphoalkyl group is an alkyl group substituted with a phospho group. The alkyl group substituted with a phospho group can be any of the alkyl groups mentioned for the carboxyalkyl group. Specific examples of the phosphoalkyl group include a phosphomethyl group, a phosphoethyl group, and a phosphopropyl group.

[0037] A phosphoalkenyl group is an alkenyl group substituted with a phospho group. The alkenyl group substituted with a phospho group can be any of the alkenyl groups described above for the carboxyalkenyl group. Specific examples of the phosphoalkenyl group include a phosphoethenyl group and a phosphopropenyl group.

[0038] Among the acidic groups, from the viewpoint of ease of introduction into starch or partial hydrolyzates thereof, acidic groups having a carboxyl group or a sulfo group are preferred, a carboxyalkyl group, a carboxyalkenyl group or a sulfoalkyl group is more preferred, a carboxyalkyl group having 1 to 5 carbon atoms is even more preferred, and a carboxymethyl group is particularly preferred.

[0039] The salt of the acidic group is preferably a metal salt of the acidic group.The metal constituting the salt includes alkali metals such as sodium, lithium, potassium, etc., and alkaline earth metals such as calcium, magnesium, barium, etc., and is preferably sodium salt, potassium salt, or calcium salt, and more preferably sodium salt or potassium salt.The metal constituting the salt can be appropriately selected according to the use of the absorbent article formed from the resin composition of the present invention, and the manufacturing process of the resin composition and the absorbent article.

[0040] In the glucose polymer, in addition to the introduction of an acidic group into starch or a partial hydrolyzate thereof, the hydrogen atom of the hydroxyl group of the glucose unit may be substituted with a functional group other than the acidic group. Examples of the functional group other than the acidic group include hydrocarbon groups such as methyl and ethyl groups, and substituents having a hydroxyl group such as hydroxypropyl and hydroxyethyl groups. The position of the hydroxyl group substituted with the functional group other than the acidic group may be any of the 1st, 2nd, 3rd, 4th, and 6th positions of the glucose unit, but the 2nd, 3rd, and 6th positions are preferred.

[0041] The molecular weight of the glucose polymer is not particularly limited, but the weight-average molecular weight calculated as pullulan by aqueous size exclusion chromatography is preferably 500,000 to 40 million, more preferably 800,000 to 35 million. If the weight-average molecular weight is less than 500,000, the water absorption performance of the water-absorbing resin made of the resin composition tends to decrease, and if it exceeds 40 million, the viscosity tends to be high and the handling properties during production tend to decrease. The weight-average molecular weight calculated as pullulan by aqueous size exclusion chromatography can be determined based on a calibration curve of molecular weight and elution time created by aqueous size exclusion chromatography using pullulan with a known molecular weight.

[0042] The content of acidic groups in the glucose polymer is preferably 0.05 to 1.8 meq / g, more preferably 0.08 to 1.0 meq / g, and even more preferably 0.1 to 0.5 meq / g. The content of acidic groups in the glucose polymer means the content of acidic groups that do not form salts. When the content of acidic groups is less than 0.05 meq / g or exceeds 1.8 meq / g, the water absorption performance of the water absorbent resin after crosslinking the glucose polymer tends to decrease. The content of acidic groups and the total acid value described later can be measured by neutralization titration using a base such as KOH.

[0043] The glucose polymer preferably has a total acid value of 0.85 to 6 meq / g, more preferably 1.2 to 5 meq / g. When a part or all of the salts of acidic groups added to starch or partial starch hydrolysates are neutralized, the total acid value means the acid value measured by returning the neutralized acidic groups to an unneutralized state, and indicates the amount of all acidic groups possessed by the glucose polymer. If the total acid value is less than 0.85 meq / g or exceeds 6 meq / g, the water-absorbing performance of the water-absorbing resin after crosslinking the glucose polymer for an aqueous solution containing electrolytes such as physiological saline tends to decrease.

[0044] When an acidic group is introduced by reacting a haloalkyl compound having an acidic group with a hydroxyl group of starch to form a glucose polymer, the amount of the introduced acidic group can also be expressed by the degree of etherification. The degree of etherification is preferably 0.1 to 2.0, more preferably 0.2 to 1.5. The degree of etherification can be determined by an ashing titration method or the like. The total acid value is detected by the introduction of an acidic group, and when the raw starch or the partial hydrolysis product of starch does not contain an acidic group, the acidic group detected by measuring the total acid value is considered to be equal to that introduced by the etherification reaction. Therefore, when the raw starch or the partial hydrolysis product of starch does not contain an acidic group, the degree of etherification may be calculated simply from the numerical value of the total acid value. For example, when the acidic group is a carboxymethyl group and all of the acidic groups are neutralized as sodium salts, the degree of etherification can be calculated by the following formula: degree of etherification = (162 x total acid value) ÷ (1000-80 x total acid value). The unit of the total acid value at this time is meq / g.

[0045] The degree of dispersion (weight average molecular weight / number average molecular weight) of the glucose polymer is not particularly limited, but is preferably 5 to 110, more preferably 7 to 70. If it is less than 5 or exceeds 110, the water absorption performance of the water-absorbent resin made of the resin composition tends to decrease. The number average molecular weight of the glucose polymer can be determined based on a calibration curve of molecular weight and elution time prepared by aqueous size exclusion chromatography using pullulan with a known molecular weight.

[0046] The biomass ratio of the glucose polymer is preferably 50% or more, and more preferably 60% or more. The biomass ratio is the ratio (mass %) of elements derived from natural resources among the elements constituting the glucose polymer.

[0047] The content of the glucose polymer in the resin composition is preferably 1 to 70% by weight, more preferably 2 to 50% by weight, and even more preferably 5 to 35% by weight. If it is less than 1% by weight, the amount of resin in the substrate after impregnation is small, so that sufficient water absorption and moisture absorption tend not to be obtained, and if it exceeds 70% by weight, the viscosity of the composition becomes too high, making impregnation and application difficult, and making it difficult to produce a uniform absorbent article.

[0048] <Method of Producing Glucose Polymer> The glucose polymer is obtained by introducing an acidic group into starch or a partial hydrolyzate thereof. The introduction of the acidic group is carried out by reacting starch or a partial hydrolyzate of starch with an acidic group-containing compound or its precursor. This reaction introduces an acidic group into the hydroxyl group of the starch or the partial hydrolyzate of starch. The acidic group-containing compound is not particularly limited as long as it can introduce the above-mentioned acidic group, and examples thereof include haloalkyl compounds having an acidic group, haloalkenyl compounds having an acidic group, acid anhydrides, and salts thereof. Examples of halogens constituting the haloalkyl compounds and haloalkenyl compounds include chlorine and bromine.

[0049] Specific examples of the acidic group-containing compound include monochloroacetic acid, monobromoacetic acid, 3-bromopropionic acid, 6-bromohexanoic acid, succinic anhydride, maleic anhydride, vinylsulfonic acid, phosphorus oxychloride, ethyl monochloroacetate, and sodium and potassium salts thereof. Specific examples of the salts include sodium monochloroacetate, potassium monochloroacetate, and sodium vinylsulfonate.

[0050] Examples of the precursor of the acidic group-containing compound include acrylonitrile, etc. As a method using acrylonitrile, for example, first, acrylonitrile is reacted with starch or a partial decomposition product thereof under basic conditions to introduce a cyanoethyl group, and the cyanoethyl group is converted to an amide group (Synthesis; 1989(12):949-950), and the obtained amide is then subjected to alkaline hydrolysis.

[0051] The reaction scheme for producing glucose polymers by reacting starch or its partial hydrolysis products with monochloroacetic acid is shown in formula (I). [ka]

[0052] The reaction scheme for producing glucose polymers by reacting starch or its partial hydrolysate with 3-bromopropionic acid is shown in formula (II). [ka]

[0053] The reaction scheme for producing glucose polymers by reacting starch or its partial hydrolysis products with 6-bromohexanoic acid is shown in formula (III). [ka]

[0054] The reaction scheme for producing glucose polymers by reacting starch or its partial hydrolysis products with succinic anhydride is shown in formula (IV). [ka]

[0055] The reaction scheme for producing glucose polymers by reacting starch or its partial hydrolysis products with maleic anhydride is shown in formula (V). [ka]

[0056] The reaction scheme for producing glucose polymers by reacting starch or its partial hydrolyzate with sodium vinyl sulfonate is shown in formula (VI). [ka]

[0057] Although the formulae (I) to (VI) show glucose polymers in which sodium salts of acidic groups have been introduced into all hydroxyl groups at the 6-position of glucose units, hydroxyl groups to which no acidic group has been introduced may remain. Also, acidic groups that have not been neutralized by salts may exist. The position at which the acidic group is introduced is not limited as long as it is a hydroxyl group present in starch or a partially hydrolyzed product thereof, and may be any of the 1-, 2-, 3-, 4-, and 6-position hydroxyl groups.

[0058] When a haloalkyl compound or a haloalkenyl compound is used as the acidic group-containing compound, it is preferable to use 1 to 1.5 equivalents of an alkali agent relative to the haloalkyl compound or the haloalkenyl compound. Examples of the alkali agent include sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, magnesium hydroxide, barium hydroxide, ammonia, sodium carbonate, and potassium carbonate. The acidic group introduced into starch or its partial hydrolysis product preferably forms a salt with sodium, potassium, lithium, calcium, magnesium, barium, ammonia, etc. derived from the alkali agent, and for this reason, it is preferable to use an amount of the alkali agent that is necessary for both the reaction of the haloalkyl compound or the haloalkenyl compound with the starch or its partial hydrolysis product and the neutralization of the acidic group of the haloalkyl compound or the haloalkenyl compound. For example, when chloroacetic acid is used as the acidic group-containing compound, it is theoretically preferable to use 2 equivalents or more of the alkali agent relative to the chloroacetic acid. When sodium chloroacetate is used, since the acidic group is neutralized in advance, it is preferable to use 1 equivalent or more of the alkali agent relative to the sodium chloroacetate. The type of metal ion constituting the alkaline agent can be appropriately selected depending on the application of the water-absorbent article formed from the resin composition of the present invention and the manufacturing process of the resin composition and the water-absorbent article.

[0059] The amount of the acidic group-containing compound used can be set arbitrarily depending on the target total acid value (degree of etherification) of the glucose polymer. Usually, 0.5 to 5.0 equivalents per 1 mol of hydroxyl groups of starch or its partial hydrolysis product are preferred, and 0.5 to 2 equivalents are more preferred. When using a haloalkyl compound such as chloroacetic acid and reacting as an aqueous solution, the introduction reaction of the acidic group and the hydrolysis reaction of the haloalkyl compound compete with each other, so that the haloalkyl compound is required in excess of the theoretical amount. The amount of the haloalkyl compound used in the aqueous solution reaction is preferably set to 5 equivalents or less relative to the theoretical value.

[0060] The reaction temperature between starch or its partial hydrolysis product and the acidic group-containing compound is not particularly limited, but is preferably 0 to 120°C. The reaction time is not particularly limited, but is preferably 1 to 24 hours. The reaction may be carried out in water, or in a mixed solvent of water and alcohols such as methanol, ethanol, 1-propanol, isopropanol, butanol, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, ethylene glycol monoethyl ether, glycol ethers such as ethylene glycol dimethyl ether, or by dispersing dried starch or its partial hydrolysis product powder in a hydrophilic solvent such as alcohols such as methanol, ethanol, isopropanol, 1-propanol, butanol, glycol ethers such as ethylene glycol dimethyl ether. When a mixed solvent is used, the proportion of the solvent other than water is preferably 50% by volume or less in the mixed solvent. A reaction kettle, an extruder, or the like can be used as a reaction apparatus.

[0061] When a haloalkyl compound such as chloroacetic acid or a salt thereof is used as the acidic group-containing compound, the reaction temperature with starch or a partial decomposition product thereof is not particularly limited, but is preferably 0 to 100°C.

[0062] In particular, when chloroacetic acid or a salt thereof is used as the haloalkyl compound, the reaction is preferably carried out at 25 to 90°C in order to prevent hydrolysis by water in the reaction solution. The reaction time is preferably the time until the raw material haloalkyl compound is consumed, and more preferably 1 to 12 hours in terms of the stability of the haloalkyl compound and the efficiency of the process. The reaction may be carried out in water, or in a mixed solvent of water and an alcohol such as methanol, ethanol, 1-propanol, isopropanol, butanol, ethylene glycol, diethylene glycol, propylene glycol, butylene glycol, ethylene glycol monoethyl ether, or a glycol ether such as ethylene glycol dimethyl ether, or the like, or the powder of dried starch or a partial decomposition product thereof may be dispersed in a hydrophilic solvent such as an alcohol such as methanol, ethanol, isopropanol, 1-propanol, butanol, or a glycol ether such as ethylene glycol dimethyl ether. When a mixed solvent is used, the proportion of the solvent other than water is preferably 50% by volume or less in the mixed solvent. A reaction kettle, an extruder, or the like can be used as the reaction apparatus.

[0063] In addition, when an acid anhydride is used as the acid group-containing compound, the reaction proceeds simply by mixing starch or its partial hydrolysis product with the acid anhydride and heating it, but in order to promote the reaction, a catalyst such as sodium carbonate, sodium hydroxide, tertiary amines such as triethylamine, imidazoles such as 2-methylimidazole, quaternary ammonium salts such as tetrabutylammonium bromide, or phosphonium salts such as tetrabutylphosphonium bromide may be used. The amount of catalyst added is preferably 0.1 equivalent or less relative to the acid group-containing compound. These catalysts may be used alone or in combination of two or more.

[0064] The reaction time is preferably the time until the raw material acid anhydride is consumed, more preferably 1 to 12 hours. The end point of the reaction can be determined by acid value measurement or IR measurement. The reaction may be carried out in water, but in order to prevent hydrolysis or alcoholysis of the acid anhydride, the reaction solvent is preferably an aprotic solvent such as dimethylsulfoxide, dimethylformamide, dimethylacetamide, or N-methylpyrrolidone. When a mixed solvent is used, the ratio of the solvent other than water is preferably 50% by volume or more in the mixed solvent. When the reaction is carried out without a solvent, the acid anhydride can play the role of a solvent, so that the reaction temperature is preferably at or above the melting point of the acid anhydride. When a solvent is used in the reaction, the reaction temperature is preferably 50 to 100°C, more preferably 70 to 90°C. A reaction kettle, an extruder, or the like can be used as a reaction apparatus.

[0065] It is preferable to neutralize a part of the salt of the acidic group added to the starch or a partial hydrolyzate thereof. By neutralization, a part of the acidic groups that formed salts are converted to free acidic groups. For example, when monochloroacetic acid is used as the above-mentioned acidic group-containing compound and sodium hydroxide is used as the alkaline agent, a sodium salt of the carboxyl group is added to the starch or a partial hydrolyzate thereof. By adding an acid to this, a part of the carboxyl group is converted to a free carboxylic acid.

[0066] The acid used for neutralization is not particularly limited, but when the acidic group is a carboxyl group, an acid having a pKa equal to or lower than that of the carboxyl group is preferred, and examples of such acids include hydrochloric acid, sulfuric acid, phosphoric acid, nitric acid, acetic acid, formic acid, trichloroacetic acid, fumaric acid, maleic acid, oxalic acid, malonic acid, succinic acid, malic acid, citric acid, and tartaric acid. For neutralization of a sulfo group or a phospho group, a strong acid is preferably used, and a mineral acid such as hydrochloric acid or sulfuric acid or a strongly acidic ion exchange resin is used. The neutralization can be carried out using a known device such as a reaction kettle or an extruder. After the addition of the acid, it is preferable to stir the mixture at 0 to 50°C for 0.2 to 1 hour for the neutralization reaction. The neutralization reaction is preferably carried out under conditions of pH 6.8 to 7.2.

[0067] In the step of introducing an acidic group or the subsequent neutralization reaction, a salt may be formed between the halogen derived from the acidic group-containing compound and the metal or ammonia derived from the alkaline agent, so it is preferable to perform desalting. As a desalting method, a glucose polymer is dissolved in water to form an aqueous solution, which is dropped into a hydrophilic solvent such as methanol, ethanol, isopropanol, acetone, or acetonitrile, and the glucose polymer is reprecipitated and recovered by filtration. Thereafter, the glucose polymer recovered by filtration is dispersed again in aqueous methanol (water content of about 70 to 90%), stirred, and then washed by a process of recovering the glucose polymer particles by filtration. As a desalting method, a method of treating an aqueous solution of the glucose polymer with a filter having an ultrafiltration membrane can be used. As a washing liquid during desalting, water or a mixture of water and a hydrophilic organic solvent such as methanol, ethanol, propanol, acetone, or acetonitrile can be used. Desalting is preferably performed until the salt concentration in the glucose polymer becomes 1% or less.

[0068] <Optional ingredients> In addition to the glucose polymer, the resin composition may contain optional components such as a solvent, a water-soluble polymer, acrylic acid and / or a salt thereof, a crosslinkable polymer, a crosslinking agent, a leveling agent, a disinfectant, a deodorant, an antibacterial agent, a fragrance, inorganic particles, a foaming agent, a pigment, a dye, a hydrophilic short fiber, an oxidizing agent, and a reducing agent.

[0069] As the solvent, water and hydrophilic solvents can be suitably used. Examples of hydrophilic solvents include methanol, ethanol, n-propanol, isopropanol, acetone, acetonitrile, ethylene glycol, propylene glycol, diethylene glycol, butylene glycol, glycerin, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol dimethyl ether, and dimethyl sulfoxide. In addition, a mixed solvent consisting of water and a hydrophilic solvent and having a hydrophilic solvent content of 60% by volume or less can also be used. In the mixed solvent, the hydrophilic solvent content is preferably 60% by volume or less, and more preferably 50% by volume or less. Among these solvents, water, a mixed solvent of water and ethanol, a mixed solvent of water and methanol, a mixed solvent of water and isopropanol, a mixed solvent of water and propylene glycol, and a mixed solution of water and butylene glycol are preferred. The content of the solvent in the resin composition is preferably 20 to 99%, and more preferably 30 to 95%. If it is less than 20%, the viscosity of the composition tends to be too high, and if it exceeds 99%, the time required for drying tends to be too long.

[0070] Examples of the water-soluble polymer include polyvinyl alcohol, polyvinylpyrrolidone, gelatin, cellulose ether, carboxymethyl cellulose, polyacrylic acid or a salt thereof, polyacrylamide, and copolymers thereof. The content of the water-soluble polymer in the resin composition is preferably 0.5 to 20% by weight, and more preferably 1 to 10% by weight.

[0071] The water absorption of the water-absorbent resin can be adjusted by adding acrylic acid and / or its salt to the resin composition. When the resin composition contains acrylic acid and / or its salt, polyacrylic acid is formed by reaction with a crosslinking agent described later, and the water-absorbent resin contains polyacrylic acid. Examples of the salt of acrylic acid include sodium salt, potassium salt, and ammonium salt. In the total amount of acrylic acid and acrylic acid salt, acrylic acid is preferably 10 to 40 mol%. The content of acrylic acid and / or its salt in the resin composition is preferably 0.5 to 100 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of glucose polymer.

[0072] When the resin composition contains acrylic acid and / or its salt, a monomer other than acrylic acid may be blended. Examples of the monomer other than acrylic acid include anionic unsaturated monomers and their salts such as methacrylic acid, maleic acid, vinyl sulfonic acid, styrene sulfonic acid, 2-(meth)acrylamide-2-methylpropanesulfonic acid, 2-(meth)acryloylethanesulfonic acid, and 2-(meth)acryloylpropanesulfonic acid; acrylamide, methacrylamide, N-ethyl(meth)acrylamide, Nn-propyl(meth)acrylamide, N-isopropyl(meth)acrylamide, N,N-dimethyl(meth)acrylamide, 2-hydroxyethyl(meth)acrylate, 2-hydroxypropyl(meth)acrylate, and 2-hydroxypropyl(meth)acrylate. Examples of the unsaturated monomers include nonionic hydrophilic group-containing unsaturated monomers such as vinylpyridine, N-vinylpyrrolidone, N-acryloylpiperidine, and N-acryloylpyrrolidine; and cationic unsaturated monomers such as N,N-dimethylaminoethyl (meth)acrylate, N,N-diethylaminoethyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylate, N,N-dimethylaminopropyl (meth)acrylamide, and quaternary salts thereof. The content of these monomers is preferably less than 30 mol% in the total amount of acrylic acid and / or its salt.

[0073] Examples of the crosslinkable polymer include compounds having an opposite charge to the glucose polymer, such as polymers having amino groups, such as chitosan, polyethyleneimine, vinylpyrrolidone-N,N-dimethylaminoethyl methacrylic acid copolymer, or salts thereof, polymers having quaternary ammonium groups, such as dimethylamine-epichlorohydrin copolymer, polydiallyldimethylammonium chloride, etc. The content of these crosslinkable polymers is preferably 90% by weight or less, more preferably 50% by weight or less, based on the total amount of the glucose polymer used as the main component.

[0074] Examples of crosslinking agents include polyethylene glycol di(meth)acrylate, N,N-methylenebis(meth)acrylamide, polypropylene glycol di(meth)acrylate, trimethylolpropane tri(meth)acrylate, glycerin tri(meth)acrylate, glycerin acrylate methacrylate, ethylene oxide modified trimethylolpropane tri(meth)acrylate, pentaerythritol hexa(meth)acrylate, triallyl cyanurate, triallyl isocyanurate, triallyl phosphate, triallylamine, (poly)ethylene glycol diglycidyl ether, glycerol diglycidyl ether, ethylenediamine, ethylene carbonate, propylene carbonate, polyethyleneimine, glycidyl ( polyvalent (meth)acrylate compounds such as (meth)acrylate; polyvalent glycidyl compounds such as ethylene glycol diglycidyl ether, polyethylene glycol diglycidyl ether, glycerol polyglycidyl ether, diglycerol polyglycidyl ether, polyglycerol polyglycidyl ether, propylene glycol diglycidyl ether, and polypropylene glycol diglycidyl ether; aqueous carbodiimide compounds; titanium alkoxide compounds such as titanium n-butoxide; titanium chelate compounds such as titanium lactate and titanium alkanolamine chelate; zirconium alkoxide compounds such as zirconium n-propoxide; zirconium chelate compounds such as zirconium acetylacetonate; and borax.

[0075] When acrylic acid and / or a salt thereof is blended in the resin composition, it is preferable to use a polyvalent (meth)acrylate compound as a crosslinking agent. The content of the crosslinking agent in the resin composition is preferably 0.05 to 10 parts by weight, more preferably 0.1 to 5 parts by weight, per 100 parts by weight of acrylic acid and / or a salt thereof.

[0076] The polyvalent glycidyl compound reacts with the acidic group or its salt of the glucose polymer into which the acidic group or its salt has been introduced to form a crosslinked structure. The content of the crosslinking agent in the resin composition is preferably such that the epoxy group of the polyvalent glycidyl compound is 0.1 to 10 mol%, more preferably 0.2 to 5 mol%, per 1 mol of the acidic group or its salt of the glucose polymer into which the acidic group or its salt has been introduced.

[0077] Examples of the leveling agent include alkyl surfactants, silicon surfactants, fluorine surfactants, metal surfactants, etc. The content of the leveling agent in the resin composition is preferably 0.001 to 5% by weight, and more preferably 0.01 to 1% by weight.

[0078] Examples of the inorganic particles include silicas such as fumed silica and colloidal silica, and metal oxides such as titanium oxide. The content of the inorganic particles in the resin composition is preferably 0.5 to 100 parts by weight, more preferably 1 to 20 parts by weight, based on 100 parts by weight of the glucose polymer.

[0079] <Water absorbent resin> The water-absorbent resin is a crosslinked product of the glucose polymer described above. The crosslinking reaction proceeds when the substrate impregnated with or coated with the resin composition of the present invention is heated and dried, and the water-absorbent resin is generated inside or on the surface of the substrate. The crosslinked structure is not particularly limited, and may be a crosslinked structure formed by chemical bonds, a crosslinked structure formed by physical bonds, or a crosslinked structure formed by both. Examples of the crosslinked structure formed by chemical bonds include crosslinked structures formed via ether bonds or ester bonds. Furthermore, it is preferable that the water-absorbent resin does not have an internal crosslinked structure formed via a covalent bond. Examples of the covalent bond include ester bonds, ether bonds, carbon-carbon covalent bonds, double bonds, and the like. Examples of the internal crosslinked structure constituting the water absorbent resin include an ionic bond between an acidic group on a glucose polymer and a neutralized acidic group, a hydrogen bond between an acidic group on a glucose polymer or its salt and a hydroxyl group on the glucose polymer, an ionic bond with a compound having an opposite charge to the glucose polymer (when the acidic group of the glucose polymer is a carboxylic acid, a compound containing a basic group such as a cationic group or an amino group), an ionic bond by a divalent alkali metal ion, a coordinate bond via a metal ion, and a hydrogen bond such as dimerization of a carboxylic acid when the acidic group is a carboxylic acid group.

[0080] Generally, water-absorbent resins having polyacrylic acid as a main structural unit have a network structure formed by covalent bonds, and form a chemical gel by absorbing water. In contrast, the water-absorbent resin made of the resin composition of the present invention is characterized in that it can form not only a chemical gel by chemical bonds, but also a physical gel by absorbing water. Since the crosslinking points of a physical gel disappear relatively easily due to the thermal motion of the molecular chains or changes in pH or ionic strength, and the physical gel can be converted into a sol having fluidity, it can also be given the property of being easily decomposed by the addition of alkali or acid, heating, shaking, etc., which leads to a reduction in the environmental load at the time of disposal.

[0081] When the physical gel is crosslinked by, for example, ionic bonds and / or hydrogen bonds, the water-absorbent resin can be dissolved and removed by alkali or acid treatment. Specifically, the water-absorbent laminate, film, or absorbent article can be immersed in an aqueous solution containing sodium hydroxide or sodium carbonate at a concentration of less than 10% by weight at room temperature for about 1 hour to dissolve the water-absorbent resin.

[0082] The water-absorbent resin is obtained by heating and drying the resin composition under a water-containing condition. The temperature during heating and drying is preferably 50 to 150°C, more preferably 60 to 130°C. The pressure during heating and drying is not particularly limited and can be performed at normal pressure, preferably 0.9 to 1.1 atm. The glucose polymers are crosslinked by heating and drying the resin composition. Crosslinks between glucose polymers can be formed by heating and drying, and there is no need to use a crosslinking agent.

[0083] <<Water-absorbent laminate>> The water-absorbent laminate of the present invention is characterized by comprising a substrate and a coating film made of a resin composition applied onto the substrate.

[0084] The material of the substrate is not particularly limited, and examples thereof include resins such as polyester, polypropylene, polyurethane, and silicone, inorganic materials such as glass and ceramics, and metals such as copper, iron, and aluminum. The shape of the substrate is not particularly limited, but is preferably a film or sheet, and the thickness thereof is generally preferably 12 to 250 μm for a film and 0.25 to 20 mm for a sheet.

[0085] The water-absorbing laminate can be produced by a method including a step of applying a resin composition onto a substrate, and a step of heating and drying the applied resin composition to form a water-absorbing layer. As the resin composition, the above-mentioned resin composition containing a glucose polymer in which an acidic group or a salt thereof is introduced into starch or a partial hydrolysis product thereof can be used. The resin composition can be applied onto the substrate by a general method such as a roll coater, a spin coater, a dip coater, or a slit coater.

[0086] In the step of heating and drying the applied resin composition to form a water-absorbing layer, the heating and drying can be performed under the temperature conditions described above with respect to the method for producing a water-absorbing resin. The heating and drying crosslinks the glucose polymers in the resin composition applied to the substrate to form a water-absorbing layer. The thickness of the water-absorbing layer is preferably 0.01 to 2 mm, and more preferably 0.1 to 1 mm. The water absorption capacity of the water-absorbing laminate is not particularly limited, but for example, it is 100 to 100,000 g / m2 of ion-exchanged water. 2 , 10 to 10,000 g / m2 in saline 2 The moisture absorption amount of the absorbent laminate is not particularly limited, but for example, it is 5 to 50 g / m2 at 25°C, 60% RH, and 1 hour. 2 At 25°C, 90% RH, and 1 hour, the viscosity is 10 to 100 g / m 2 It is.

[0087] <<Water-absorbent film>> The water-absorbent film of the present invention is characterized by being made of the above-mentioned resin composition. The thickness of the water-absorbent film is preferably 0.01 to 2 mm, and more preferably 0.02 to 1 mm. The water absorption capacity of the water-absorbent film varies depending on the thickness. The water absorption capacity is not particularly limited, but for example, when the film is 0.2 mm thick, it can absorb 5,000 to 560,000 g / m 2 of ion-exchanged water. 2 It is preferable to use saline at 500 to 140,000 g / m 2 It is preferable that:

[0088] The water-absorbing film can be manufactured by a method including a step of applying a resin composition onto a releasable substrate, and a step of heating and drying the applied resin composition to form a water-absorbing layer. As the releasable substrate, the substrate of the water-absorbing laminate described above can be used as it is, or a substrate to which a release agent has been applied to impart releasability can also be used. As the substrate, the substrate described for the water-absorbing laminate can be used. As the release agent, silicone compounds such as polydimethylsiloxane, PTFE, fluorine compounds such as perfluoropolyether, etc. can be mentioned. The application of the resin composition and the heating and drying of the applied resin composition can be performed by the same method and conditions as the manufacturing method of the water-absorbing laminate described above. After the step of forming the water-absorbing layer, it is preferable to peel the water-absorbing layer from the releasable substrate. The peeled water-absorbing layer can be used as a water-absorbing film.

[0089] <<Water absorbent articles>> The water-absorbent article of the present invention is characterized by comprising a water-absorbent resin comprising a matrix and a resin composition present in the matrix.

[0090] The matrix is ​​a porous body capable of supporting the water-absorbent resin. Examples of such porous bodies include nonwoven fabrics, woven fabrics, foams, and metal porous bodies. The material of the fibers constituting the nonwoven fabrics and woven fabrics is not particularly limited, and examples thereof include natural fibers such as cellulose, cotton, and silk, synthetic fibers such as polyester, polypropylene, polyurethane, and rayon, inorganic materials such as glass and carbon fiber, and metals such as copper, stainless steel, titanium, and silver. The diameter of the fibers is preferably 0.1 to 20 μm, and more preferably 0.5 to 10 μm. When the porous body is a foam, examples of the constituent materials thereof include resins such as polyethylene, polypropylene, polymethyl methacrylate, and polyurethane, metals such as copper and stainless steel, and ceramics. The basis weight of the nonwoven fabrics and woven fabrics is 10 to 250 g / cm. 2 The pore size of the porous body is preferably 10 μm to 1.3 mm, more preferably 20 μm to 0.5 mm. The thickness of the matrix is ​​not particularly limited, but is preferably 0.5 to 20 mm.

[0091] The water-absorbent article can be manufactured by a method including a step of impregnating a matrix with a resin composition and a step of heating and drying the impregnated resin composition. As the resin composition, the above-mentioned resin composition containing a glucose polymer in which an acidic group or a salt thereof is introduced into starch or a partial hydrolysis product thereof can be used. In the step of impregnating a matrix with the resin composition, the amount of the resin composition impregnated into the matrix is ​​preferably 50 to 2000 parts by weight per 100 parts by weight of the matrix. The specific impregnation method is not particularly limited, and can be performed by a general method such as dripping the resin composition into the matrix or immersing the matrix in the resin composition.

[0092] In the step of drying the impregnated resin composition by heating, the drying by heating can be performed under the temperature conditions described above with respect to the method for producing the water-absorbing resin. By drying the resin composition by heating, glucose polymers present in the porous portion of the matrix are crosslinked with each other. In the water-absorbing article obtained by the drying by heating, the amount of the water-absorbing resin present in the matrix is ​​preferably 2 to 700 parts by weight per 100 parts by weight of the matrix.

[0093] <Application> The water-absorbent laminate, water-absorbent film, and absorbent article of the present invention can be used as sanitary products, medical products, civil engineering products, food preservation products, agricultural and horticultural products, various packaging materials, etc. Starch is synthesized by plants absorbing carbon dioxide from the atmosphere. Therefore, even if carbon dioxide is generated by decomposition or incineration, products obtained by using the water-absorbent laminate, water-absorbent film, and absorbent article of the present invention can suppress the increase in greenhouse gases as a whole and contribute to carbon neutrality.

[0094] Examples of sanitary products include disposable diapers, sanitary products, incontinence pads, breast pads, masks for packs, portable toilets, pet toilets, cat litter, face masks, etc. Examples of medical products include hemostatic sponges (medical pads), wound protection materials, wound healing materials, medical waste solidification agents, ice packs, carriers for drug delivery systems, artificial joints, compresses, etc.

[0095] Civil engineering products include waterproofing materials, waste liquid solidification agents, waste soil solidification agents, construction materials for preventing condensation, and slope greening sheets.

[0096] Food preservation products include ice packs, cooling gels, water retention materials, condensation prevention sheets, drip absorbents, and freshness preserving agents.

[0097] Examples of agricultural and horticultural products include soil conditioners, soil water retention materials, seed coatings, seedling sheets, seedling pots, seedling beds, hydroponic cultivation supports, fertilizer retention materials, fertilizer slow-release agents, etc. Other uses include air fresheners, disposable hand warmers, portable toilets, etc.

[0098] Examples of packaging materials include functional cardboard that is provided with moisture-regulating functions and water resistance, and moisture-absorbing packaging materials used for storing food, medicine, etc.

[0099] <Disposable diapers, napkins> The absorbent laminate, absorbent film, and absorbent article of the present invention can be suitably used as an absorbent body for paper diapers and napkins. The absorbent laminate, absorbent film, and absorbent article of the present invention can be used as an absorbent body as it is, but may also be used after being wrapped in a core wrap made of a paper sheet or a liquid-permeable nonwoven fabric.

[0100] The absorbent body may contain hydrophilic fibers and water-absorbent resins in addition to the water-absorbent laminate, water-absorbent film, and absorbent article of the present invention. Examples of hydrophilic fibers include natural hydrophilic fibers such as absorbent paper, pulp, acetate, tissue, hydrophilic nonwoven fabric, cotton, etc., natural hydrophilic fibers based on cellulose such as lyocell, rayon, and cupra, and petroleum-derived hydrophilic fibers obtained by treating acrylic fibers. Examples of water-absorbent resins include polyacrylic acid, polyaspartic acid, and starch-acrylonitrile.

[0101] The paper diaper or napkin may have a laminated structure in which, for example, a top sheet, an absorbent, and a back sheet are laminated in this order. The top sheet is a sheet that contacts the wearer's body when the paper diaper or napkin is worn. The top sheet is preferably liquid-permeable, and may be made of a hydrophilic nonwoven fabric, a porous resin film, or the like. The back sheet is a sheet that is positioned on the outside and does not contact the wearer's body. The back sheet is preferably liquid-impermeable, and may be made of a hydrophobic nonwoven fabric, a resin film, a laminate of a nonwoven fabric and a resin film, or the like.

[0102] <Regenerated glucose polymer> When the absorbent laminate, absorbent film, or absorbent article of the present invention is contacted with an alkaline agent, the crosslinked structures and glycoside bonds between glucose polymers in the absorbent resin can be cleaved, and regenerated glucose polymers can be recovered.

[0103] The pH condition during the alkali treatment is preferably pH 9.0 or more, more preferably pH 10.0 or more. The alkaline agent used in the alkali treatment is not particularly limited, but examples thereof include sodium hydroxide, potassium hydroxide, lithium hydroxide, ammonia, sodium carbonate, and potassium carbonate. When the alkali treatment is performed using an alkaline aqueous solution, the concentration of the alkaline agent in the aqueous solution is preferably 0.01 to 20% by weight. The temperature during the alkali treatment is preferably 5 to 70°C. The time for carrying out the alkali treatment is preferably 1 to 120 minutes. After the alkali treatment, the recovered regenerated glucose polymer may be neutralized by adding an acid, concentrated, washed, filtered, or the like as necessary. The regenerated glucose polymer preferably has the molecular weight, dispersity, total acid value, and acidic group content described above for the glucose polymer.

[0104] A water-absorbent resin can be obtained by crosslinking the regenerated glucose polymer. The crosslinking method and crosslinking structure of the regenerated glucose polymer are preferably the crosslinking method and crosslinking structure described above for the glucose polymer. The water-absorbent resin obtained by crosslinking the regenerated glucose polymer preferably has the physical properties of the water-absorbent resin described above. The water-absorbency of ion-exchanged water under no pressure, the water-retention rate of ion-exchanged water, the water-absorbency of physiological saline under no pressure, and the water-retention rate of physiological saline of the water-absorbent resin obtained by crosslinking the regenerated glucose polymer are preferably 60 to 140%, more preferably 80 to 120%, even more preferably 90 to 110%, and particularly preferably 95 to 105%, respectively, relative to the same water-absorbent properties of the water-absorbent resin obtained by crosslinking a glucose polymer that is not a regenerated product.

[0105] The water-absorbing resin obtained by crosslinking the regenerated glucose polymer can be used to obtain an absorbent article, the structure and use of which are as described above.

[0106] When the absorbent laminate, absorbent film, and absorbent article of the present invention contain a matrix or a substrate, the absorbent resin is decomposed into a glucose polymer by alkali treatment, and the matrix or substrate is obtained as a solid residue. These matrices and substrates can be reused as necessary. For example, when the matrix is ​​made of natural hydrophilic fibers such as pulp or cotton, the hydrophilic fibers obtained as a solid residue can be dried and, if necessary, disintegrated and defibrated, and used to manufacture absorbent articles such as paper diapers. They can also be used for general purposes such as industrial wipers, waste liquid absorbents, and filters. By adjusting the molecular weight, total acid value, acidic group content, dispersity, etc. of the glucose polymer in the present invention, the absorbent resin can be given decomposition or biodegradability by alkali treatment according to the intended use. EXAMPLES

[0107] The present invention will be described below with reference to examples, but the present invention is not limited to the following examples. In the following, "parts" and "%" mean "parts by weight" and "% by weight", respectively, unless otherwise specified.

[0108] (Production Example 1) Production of partial starch hydrolysate derived from tapioca starch (1) Tapioca starch was suspended in city water to a concentration of 45% (w / w), and then 1N sodium hydroxide was added to adjust the pH to 6.0 to obtain starch milk. Amylomaltase crude enzyme solution was added to this starch milk so that the amount was 8.0 units per gram of starch solids, and the mixture was stirred at room temperature for 30 minutes, and then reacted at 95°C for 6 hours while stirring to prepare liquefied starch. The weight-average molecular weight of the resulting partial starch hydrolyzate was 2.61 million, and the degree of dispersion was 7.9.

[0109] (Production Example 2) Production of glucose polymer derived from tapioca starch (1) 100 g of a 45 wt % aqueous solution of the tapioca starch-derived starch hydrolysate obtained in Production Example 1 (0.83 mol of hydroxyl groups of the partial starch hydrolysate) was charged into a 500 ml separable flask equipped with a stirrer, a thermometer, and a cooling tube. Next, 34.0 g of a 48.8% aqueous solution of sodium hydroxide (0.42 mol, 0.50 mol equivalent to 1 mol of hydroxyl groups of the partial starch hydrolysate) was charged, and the solution was stirred at 60°C or less until it became completely uniform. After confirming that the solution became uniform, an aqueous solution of 19.8 g of monochloroacetic acid (0.21 mol, 0.3 mol equivalent to 1 mol of hydroxyl groups of the partial starch hydrolysate) dissolved in 50 g of ion-exchanged water was added dropwise at 50 to 60°C over 30 minutes. After charging the aqueous solution of monochloroacetic acid, the temperature was adjusted to 45 to 50°C, and the mixture was stirred for 12 hours. The end point of the reaction was determined by sampling the reaction solution, measuring the chloride ion content in the reaction solution by potentiometric titration using a 0.01N silver nitrate aqueous solution, and determining that the chloride ion content reached 98% or more of the calculated value of 3.7% when all the monochloroacetic acid had reacted. In this production example, the chloride content was 3.7%.

[0110] After the reaction was completed, the reaction solution was diluted with 900 g of ion-exchanged water. The diluted reaction solution was cooled to room temperature and added to 6000 ml of methanol over about 30 minutes to precipitate and reprecipitate the glucose polymer. After all the reaction solution was added, the mixture was stirred for 30 minutes, and the glucose polymer dispersed in the methanol was subjected to solid-liquid separation by vacuum filtration.

[0111] Subsequently, the recovered glucose polymer was redispersed in 1000 ml of aqueous methanol with methanol / water = 80 / 20 (weight ratio), 11 ml of 1N hydrochloric acid solution was added, and after stirring at room temperature for 30 minutes, solid-liquid separation was performed by vacuum filtration, and the glucose polymer was recovered again. The chlorine content of the recovered glucose polymer was measured by potentiometric titration using a 0.01N silver nitrate aqueous solution, and if the chlorine content exceeded 1%, the recovered water-soluble polymer was redispersed in 1000 ml of aqueous methanol with methanol / water = 80 / 20 (weight ratio), stirred at room temperature for 30 minutes, washed, and the washing process was repeated until the chlorine content was less than 1%. The obtained glucose polymer was in a wet state containing methanol and water with a weight ratio of methanol / water = 80 / 20 (weight ratio), and its solid content was 32%. The total acid value of the obtained glucose polymer was 2.32 meq / g, the degree of etherification calculated from the total acid value was 0.46, the weight-average molecular weight was 8.12 million, the degree of polydispersity was 13.7, and the biomass degree was 81%.

[0112] (Production Example 3) Production of Varnish 1 62.5g of the wet glucose polymer obtained in Production Example 2 was dissolved in 37.5g of ion-exchanged water, then 3.6g of 1N hydrochloric acid solution was added and stirred for 10 minutes to prepare varnish 1. The concentration of the glucose polymer in this varnish was about 20%, and the composition ratio of the solvent was about methanol / water=60 / 40 (weight ratio). The content of acidic groups in the glucose polymer was 0.18meq / g.

[0113] (Production Example 4) Production of water-soluble polymer derived from tapioca starch (2) 100 g of a 45 wt % aqueous solution of the tapioca starch-derived starch hydrolysate obtained in Production Example 1 (0.83 mol of hydroxyl groups of the partial starch hydrolysate) was charged into a 500 ml separable flask equipped with a stirrer, a thermometer, and a cooling tube. Next, 34.0 g of a 48.8% aqueous solution of sodium hydroxide (0.42 mol, 0.50 mol equivalent to 1 mol of hydroxyl groups of the partial starch hydrolysate) was charged, and the solution was stirred at 60°C or less until it became completely uniform. After confirming that the solution became uniform, an aqueous solution of 19.8 g of monochloroacetic acid (0.21 mol, 0.3 mol equivalent to 1 mol of hydroxyl groups of the partial starch hydrolysate) dissolved in 50 g of ion-exchanged water was added dropwise at 50 to 60°C over 30 minutes. After charging the aqueous solution of monochloroacetic acid, the temperature was adjusted to 45 to 50°C, and the mixture was stirred for 12 hours. The end point of the reaction was determined by sampling the reaction solution, measuring the chloride ion content in the reaction solution by potentiometric titration using a 0.01N silver nitrate aqueous solution, and determining that the chloride ion content reached 98% or more of the calculated value of 3.7% when all the monochloroacetic acid had reacted. In this production example, the chloride content was 3.7%.

[0114] After the reaction was completed, the reaction solution was diluted with 900 g of ion-exchanged water. The diluted reaction solution was cooled to room temperature, 4.3 g of fumaric acid was added, and the mixture was stirred for 1 hour to perform neutralization. The reaction mixture was then added to 6000 ml of methanol over about 30 minutes to precipitate and reprecipitate the water-soluble polymer. After all the reaction solution was added, the mixture was stirred for 30 minutes, and the water-soluble polymer dispersed in the methanol was subjected to solid-liquid separation by vacuum filtration.

[0115] The recovered water-soluble polymer was then redispersed in 1000 ml of aqueous methanol (methanol / water = 80 / 20 (weight ratio)), stirred at room temperature for 30 minutes, and then subjected to solid-liquid separation by vacuum filtration, and the water-soluble polymer was recovered again. The chlorine content of the recovered water-soluble polymer was measured by potentiometric titration using a 0.01N silver nitrate aqueous solution, and if the chlorine content exceeded 1%, the recovered water-soluble polymer was redispersed in 1000 ml of aqueous methanol (methanol / water = 80 / 20 (weight ratio)), stirred at room temperature for 30 minutes, washed, and the washing process was repeated until the chlorine content was less than 1%. The obtained water-soluble polymer was in a wet state containing methanol / water = 80 / 20 (weight ratio), and its solid content was 32%. The total acid value of the obtained water-soluble polymer was 2.55 meq / g, the degree of etherification calculated from the total acid value was 0.52, the content of acidic groups was 0.35 meq / g, the weight-average molecular weight was 9.2 million, the degree of polydispersity was 13.5, and the biomass degree was 80%.

[0116] (Production Example 5) Production of Varnish 2 31.2 g of the water-soluble polymer in a wet state containing methanol / water = 80 / 20 (weight ratio) obtained in Production Example 4 was dissolved in 90.0 g of ion-exchanged water to prepare varnish 2. The composition ratio of the solvent in this varnish was about methanol / water = 86 / 14 (weight ratio).

[0117] (Example 1) Impregnation of filter paper 55mm diameter circular qualitative filter paper No.2 (Advantec Toyo Co., Ltd., 125g / m 2 ) was weighed. Next, about 1 g of the varnish 1 obtained in Production Example 3 was placed on the filter paper using a dropper and allowed to soak into the entire filter paper and impregnate it. The filter paper was then dried for 1 hour in a blower dryer set at 120°C to generate a water-absorbent resin in the filter paper, thus producing a water-absorbent body. The weight (B) of the water-absorbent body was weighed, and the amount of resin attached was calculated using the following formula. Resin adhesion amount (g / m 2 ) = (Weight (B) - Weight (A)) ÷ Water absorber area (m 2 )

[0118] (Water absorption test) The absorbent samples were immersed in 0.9% saline or distilled water for 10 minutes. After immersion, they were removed from the net for 1 minute, drained, and then weighed after absorption (C) to calculate the amount of absorbed water per unit area. Water absorption (g / m 2 ) = (Weight (C) - Weight (B)) ÷ Water absorber area (m 2 )

[0119] (Moisture absorption test) The water-absorbent sample was allowed to absorb moisture in a thermohygrostat set under the following conditions: The moisture absorption was continued for 4 hours, and the sample was taken out at the 1st and 4th hour, the weight (D) of the water-absorbent sample was measured, and the amount of moisture absorbed per unit area was calculated. (1)25℃, 60%RH, (2)25℃, 90%RH, (3)35℃, 60%RH, (4)15℃, 90%RH Moisture absorption amount (g / m 2 ) = (Weight (D) - Weight (B)) ÷ Water absorber area (m 2 )

[0120] (Example 2) Impregnation into polypropylene nonwoven fabric The filter paper was cut into a size of 5 cm length and 5 cm width and then wrapped around a polypropylene nonwoven fabric (MonotaRO Co., Ltd., basis weight 20 g / m 2 ) and the amount of varnish 1 was changed to about 0.5 g, and a water-absorbing material was prepared in the same manner as in Example 1, and a water absorption test and a moisture absorption test were carried out.

[0121] (Example 3) Impregnation into polyester nonwoven fabric Polypropylene nonwoven fabric cut into a size of 5 cm length and 5 cm width to make polyester nonwoven fabric (made by Sasagawa, basis weight 20 g / cm 2 ), a water absorbent material was prepared in the same manner as in Example 2, and a water absorption test and a moisture absorption test were carried out.

[0122] (Example 4) Impregnation of absorbent cotton Except for changing the filter paper to cut cotton (manufactured by Kawamoto Sangyo Co., Ltd.) measuring 40 mm in length, 40 mm in width, and 5 mm in thickness, and changing the varnish added to 1.2 g of Varnish 2, a water absorbent body was prepared in the same manner as in Example 1, and a water absorption test and a moisture absorption test were performed.

[0123] (Comparative Examples 1 to 4) The nonwoven fabric, absorbent cotton, and filter paper used in Examples 1 to 4 were subjected to the same water absorption test and moisture absorption test as in Examples 1 to 4, without being impregnated with varnish.

[0124] [Table 1]

[0125] As shown in Table 1, compared to Comparative Examples 1 to 4 which were not impregnated with varnish, Examples 1 to 4 which were impregnated with varnish had improved water absorption performance and moisture absorption performance.

[0126] (Example 5) Preparation of water-absorbent film 65 g of varnish 1 was placed in a PTFE petri dish with an inner diameter of 90 mm, and dried in a blower dryer at 85°C for 6 hours, and then further dried at 105°C for 2 hours. After drying, a water-absorbent film was formed in the petri dish. This water-absorbent film was taken out, and test pieces of 40 mm square and 20 mm square were cut out, and the weights of each were measured. The weight of the 40 mm square test piece was W 40 , the weight of the 20 mm square test piece is W 20 Figure 1 shows photographs of a 40 mm square test piece (right) and a 20 mm square test piece (left).

[0127] (Evaluation of water absorption of water-absorbing film) Physiological saline was placed in a glass petri dish with an outer diameter of 112 mm and a height of 18 mm. A 40 mm square test piece of the prepared water-absorbent film was immersed in the physiological saline in the glass petri dish and allowed to absorb water for 1 hour. In addition, ion-exchanged water was placed in a similar glass petri dish, and a 20 mm square test piece was immersed in the water and allowed to absorb water for 1 hour. After 1 hour, the entire contents of the petri dish were poured onto a 10-mesh test sieve with an inner diameter of 75 mm, and after draining for 5 minutes, the weight of the gel remaining on the sieve was measured. The weight of the gel in the 40 mm square test piece was W 40-2 , the weight of the 20 mm square test piece is W 20-2 The water absorption of each test piece was calculated using the following formula. Water absorption of physiological saline solution: Water absorption of a 40 mm square test piece (g / m 2 )=(W40-2 -W 40 )÷16×10,000 Absorption of ion-exchanged water: Absorption of 20 mm square test piece (g / m 2 )=(W 20-2 -W 20 )÷4×10,000

[0128] [Table 2]

[0129] The water-absorbent film of Example 5 exhibited excellent water absorbency for both physiological saline and ionized water.

[0130] The present invention may include, for example, the following aspects. <1> A resin composition for coating or impregnation, comprising a glucose polymer in which an acidic group or a salt thereof has been introduced into starch or a partially hydrolyzed product thereof.

[0131] <2> Item 2. The resin composition according to item 1, wherein the glucose polymer has an acidic group content of 0.05 to 1.8 meq / g.

[0132] <3> Item 3. The resin composition according to item 1 or 2, wherein the acidic group is a carboxyalkyl group, a carboxyalkenyl group, or a sulfoalkyl group.

[0133] <4> moreover, Water, or A mixed solvent consisting of water and a hydrophilic solvent, with the hydrophilic solvent content being 60% by volume or less. The resin composition according to any one of items 1 to 3, comprising:

[0134] <5> A substrate, and A coating film made of the resin composition according to any one of items 1 to 4, applied onto the substrate. A water-absorbent laminate comprising:

[0135] <6> A step of applying the resin composition according to any one of items 1 to 4 onto a substrate; and A process of heating and drying the applied resin composition to form a water absorbing layer. Including, A method for producing a water-absorbent laminate.

[0136] <7> Item 5. A water-absorbent film comprising the resin composition according to any one of items 1 to 4.

[0137] <8> A step of applying the resin composition according to any one of items 1 to 4 onto a releasable substrate; and A process of heating and drying the applied resin composition to form a water absorbing layer. Including, A method for producing a water-absorbent film.

[0138] <9> 5. A water-absorbent article comprising a matrix and a water-absorbent resin comprising the resin composition according to any one of items 1 to 4, present in the matrix.

[0139] <10> The matrix is ​​made of cellulose or resin. Item 10. The absorbent article according to item 9.

[0140] <11> A step of impregnating a matrix with the resin composition according to any one of items 1 to 4; and A step of heating and drying the impregnated resin composition Including, A method for producing an absorbent article.

Claims

1. A resin composition for coating or impregnation, comprising a glucose polymer in which an acidic group or a salt thereof has been introduced into starch or a partially hydrolyzed product thereof.

2. The resin composition according to claim 1, wherein the glucose polymer has an acidic group content of 0.05 to 1.8 meq / g.

3. 3. The resin composition according to claim 1, wherein the acidic group is a carboxyalkyl group, a carboxyalkenyl group, or a sulfoalkyl group.

4. moreover, Water, or A mixed solvent consisting of water and a hydrophilic solvent, the content of the hydrophilic solvent being 60% by volume or less. The resin composition according to claim 1 or 2, comprising:

5. A substrate, and A coating film comprising the resin composition according to claim 1 or 2, which is applied onto the substrate. A water-absorbent laminate comprising:

6. A step of applying the resin composition according to claim 1 or 2 onto a substrate; and A process of heating and drying the applied resin composition to form a water absorbing layer. Including, A method for producing a water-absorbent laminate.

7. A water-absorbent film comprising the resin composition according to claim 1 or 2.

8. A step of applying the resin composition according to claim 1 or 2 onto a releasable substrate; and A process of heating and drying the applied resin composition to form a water absorbing layer. Including, A method for producing a water-absorbent film.

9. A water-absorbent article comprising a matrix and a water-absorbent resin comprising the resin composition according to claim 1 or 2 present in the matrix.

10. The matrix is ​​made of cellulose or resin. The absorbent article according to claim 9.

11. Impregnating a matrix with the resin composition according to claim 1 or 2; and A step of heating and drying the impregnated resin composition Including, A method for producing an absorbent article.

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