JP2018053401A - Zwitterionic fiber - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a natural fiber having an amphoteric ion exchange ability. The present invention relates to an amphoteric fiber having an ionic functional group and containing a first polymer which is a natural polymer as a base material. The amphoteric fiber of the present invention includes a natural polymer having an acidic substituent or a basic substituent, and a polymer having an acidic substituent or a basic substituent having a charge opposite to that of the natural polymer. It is preferably an amphoteric fiber containing. [Selection diagram] None

Description

  The present invention relates to zwitterionic fibers. Specifically, the present invention relates to an amphoteric fiber containing a natural polymer as a base material.

  Conventionally, ion exchange resins are used in industrial products such as chromatography fillers and filters. As ion exchange resins, there are known those in which a substance having an ion-adsorbing functional group is supported on a carrier using various resins as carriers, and those in which an ion-adsorbing functional group is directly bonded to a carrier resin. For example, Patent Document 1 discloses a cellulose phosphate ester having a cellulose fiber as a carrier and a phosphate group as an ion-adsorbing functional group. Here, cellulose II is obtained by subjecting cellulose I, which is a natural cellulose fiber, to alkali treatment, and the use of cellulose II phosphate as a metal adsorbent has been studied.

  In addition, amphoteric ion exchange resins are also known as ion exchange resins. As an amphoteric ion exchange resin, a resin in which an anionic functional group and a cationic functional group are chemically bonded to the upper surface of a carrier resin is known. For example, Patent Document 2 discloses a method for producing an amphoteric ion exchange resin by reacting a resin obtained by polymerizing a polymerizable monomer having a carbon-hydrogen bond with an amphoteric functional group introducing agent. . Here, a compound having an anionic functional group and a cationic functional group in one molecule is used as the amphoteric functional group introducing agent.

  Patent Document 3 discloses an amphoteric ion exchanger fiber sheet in which a particulate anion exchange resin and a cation exchange resin are supported on a resin fiber sheet. Here, although the resin fiber sheet itself does not have an ion-adsorbing functional group, the amphoteric ion exchanger fiber sheet is configured by supporting various resins having an ion-adsorbing functional group on the fiber sheet.

International Publication No. 2005/042587 JP 2014-118512 A Japanese Patent Laying-Open No. 2015-167876

As described above, various ion exchange resins are known, but none of the natural fibers themselves have amphoteric ion exchange ability, and development of natural fibers having amphoteric ion exchange ability has been demanded.
Therefore, the present inventors proceeded with studies for the purpose of providing a natural fiber having an amphoteric ion exchange ability.

As a result of intensive studies to solve the above-mentioned problems, the present inventors have incorporated a natural polymer having an ionic functional group as a base material, thereby providing an amphoteric ion-exchangeable zwitterionic fiber. Succeeded in getting.
Specifically, the present invention has the following configuration.

[1] An amphoteric fiber having an ionic functional group and a first polymer which is a natural polymer as a base material.
[2] The first polymer has an acidic substituent or a basic substituent, and the zwitterionic fiber has an acidic substituent or basic substituent having a charge opposite to that of the first polymer polymer. The zwitterionic fiber according to [1], comprising a second polymer having
[3] The zwitterionic fiber according to [2], wherein the first polymer has an acidic substituent, and the second polymer is a polymer having a basic substituent.
[4] The zwitterionic fiber according to [2], wherein the first polymer has a basic substituent, and the second polymer has a acidic substituent.
[5] The zwitterionic fiber according to any one of [1] to [4], wherein the first polymer is at least one selected from cellulose, starch, and chitosan.

  According to the present invention, a natural fiber having an amphoteric ion exchange ability can be obtained.

FIG. 1 is a graph showing the relationship between the NaOH dripping amount and the pH relative to the fiber raw material. FIG. 2 is a graph showing the relationship between the amount of dropped NaOH and electrical conductivity for a fiber material having a carboxyl group.

  Hereinafter, the present invention will be described in detail. The description of the constituent elements described below may be made based on representative embodiments and specific examples, but the present invention is not limited to such embodiments.

(Zwitterionic fiber)
The present invention relates to an amphoteric fiber having an ionic functional group and a first polymer which is a natural polymer as a base material. The zwitterionic fiber of the present invention is such that the natural fiber itself comprising a natural polymer has zwitterion exchange capacity. Here, the amphoteric ion exchange capacity means both anion exchange capacity and cation exchange capacity.

The zwitterionic fiber of the present invention may be a zwitterionic fiber obtained by reacting a natural fiber with a compound having an anionic functional group and a cationic functional group. In this case, the zwitterionic fiber of the present invention may be one in which the natural fiber has a zwitterionic functional group.
Further, the zwitterionic fiber of the present invention has a polymer having an anionic functional group and a polymer having a cationic functional group, and at least one of the polymers is a natural polymer. It may be a natural fiber. In this case, zwitterionic fibers are formed by the two polymers adsorbing (interacting) with each other and becoming fibrous.

  In the present invention, the anionic functional group is preferably an acidic functional group (hereinafter also referred to as an acidic substituent), and the cationic functional group is a basic functional group (hereinafter also referred to as a basic substituent). Preferably there is. And the zwitterionic fiber of the present invention has a polymer having an acidic substituent (acidic polymer) and a polymer having a basic substituent (basic polymer), and at least one of the polymers Is preferably a zwitterionic fiber which is a natural polymer. That is, the first polymer that has an ionic functional group and is a natural polymer has an acidic substituent or a basic substituent, and the zwitterionic fiber is opposite to the charge of the first polymer. It is preferable that it contains the 2nd polymer | macromolecule which has an acidic substituent or basic substituent of the following electric charge.

  In the present specification, the second polymer may be a synthetic polymer or a natural polymer. When the second polymer described above is a synthetic polymer, the zwitterionic fiber of the present invention includes a natural polymer having an acidic substituent or a basic substituent (first polymer) and a charge possessed by the natural polymer. And a synthetic polymer (second polymer) having an acidic substituent or a basic substituent of the opposite charge. When the second polymer described above is a natural polymer, the zwitterionic fiber of the present invention includes a first natural polymer (first polymer) having an acidic substituent or a basic substituent, and a natural polymer. A zwitterionic fiber including a second natural polymer (second polymer) having an acidic substituent or a basic substituent having a charge opposite to that of the polymer. When the second polymer is a natural polymer, the first polymer and the second polymer may be the same natural polymer or different natural polymers. From the viewpoint of handleability and cost, the first polymer and the second polymer are preferably the same natural polymer.

  In a preferred first embodiment of the zwitterionic fiber of the present invention, the first polymer having an ionic functional group and being a natural polymer has an acidic substituent, and the second polymer is a base. Having a functional substituent. In the first embodiment, the first polymer has an acidic substituent, and the acidic substituent in this case is, for example, a phosphate group or a substituent derived from a phosphate group (simply referred to as a phosphate group). Or a substituent derived from a carboxyl group or a carboxyl group (sometimes simply referred to as a carboxyl group) and a sulfone group or a substituent derived from a sulfone group (sometimes referred to simply as a sulfone group). It is preferably at least one, more preferably at least one selected from a phosphate group and a carboxyl group, and particularly preferably a phosphate group. In the first embodiment, the second polymer preferably has a basic substituent, and the second polymer is preferably a synthetic polymer. In this case, the basic substituent is preferably at least one selected from, for example, a primary amino group, a secondary amino group, a tertiary amino group, and a quaternary ammonium group. It is more preferably at least one selected from amino groups, and even more preferably a primary amino group.

In the first embodiment, the first polymer preferably has a phosphate group. The phosphoric acid group is a divalent functional group corresponding to the phosphoric acid obtained by removing the hydroxyl group. Specifically, it is a group represented by —PO ₃ H ₂ . The substituent derived from the phosphate group includes a substituent such as a group obtained by polycondensation of the phosphate group, a salt of the phosphate group, and a phosphate ester group, and is preferably an ionic substituent.

Further, the phosphate group may be a substituent represented by the following formula (1).

In the formula (1), a, b, m and n each independently represent an integer (where a = b × m); α ⁿ (n is an integer from 1 to n) and α ′ are each independently Represents R or OR. R represents a hydrogen atom, a saturated-linear hydrocarbon group, a saturated-branched hydrocarbon group, a saturated-cyclic hydrocarbon group, an unsaturated-linear hydrocarbon group, an unsaturated-branched hydrocarbon group. , An aromatic group, or a derivative group thereof; β is a monovalent or higher cation composed of an organic substance or an inorganic substance.

In the first embodiment, the second polymer is preferably a synthetic polymer, and the basic substituent that the synthetic polymer may have is preferably a primary amino group. For example, the second polymer having a basic substituent preferably includes the following structure as a structural unit. In the following structural formula, n represents an integer of 2 or more.

  In a preferred second embodiment of the zwitterionic fiber of the present invention, the first polymer has a basic substituent, and the second polymer has an acidic substituent. In the second embodiment, the first polymer has a basic substituent. In this case, examples of the basic substituent include a primary amino group, a secondary amino group, a tertiary amino group, and 4 It is preferably at least one selected from quaternary ammonium groups, and more preferably quaternary ammonium groups. In the second embodiment, the second polymer preferably has an acidic substituent, and the second polymer is also preferably a natural polymer. The acidic substituent in this case is preferably at least one selected from, for example, a phosphate group, a carboxyl group, and a sulfone group, and preferably at least one selected from a phosphate group and a carboxyl group. More preferred is a phosphate group.

In the second embodiment, the quaternary ammonium group that the first polymer may have is preferably a group represented by the following structural formula.

In the above structural formula, R ^{1 to} R ³ each independently represents an organic group, and R ⁴ represents a single bond or a divalent linking group. R ^{1 to} R ³ each independently preferably represents an alkyl group, and more preferably represents an alkyl group having 1 to 5 carbon atoms. R ⁴ preferably represents an alkylene group, more preferably an alkylene group having 1 to 5 carbon atoms. X ⁻ is a monovalent anion composed of an organic substance or an inorganic substance, and preferably represents a fluoride ion, a chloride ion, a bromide ion, an acetate ion, a propionic acid, or a hydroxide ion. Is preferably represented.

  In the second embodiment, the acidic substituent that the polymer may have is preferably a phosphate group, and examples of the phosphate group include the above-described phosphate groups.

  In the present invention, the natural polymer is preferably at least one selected from cellulose, starch, chitin and chitosan, and more preferably cellulose fibers. The polymer may be a natural polymer selected from at least one selected from cellulose, starch, chitin, and chitosan, or may be a synthetic polymer (hereinafter also referred to as a synthetic resin). Examples of the synthetic resin include a resin obtained by polymerizing a polymerizable monomer having a carbon-hydrogen bond. Examples of the polymerizable monomer having a carbon-hydrogen bond include allylamine, dimethylaminopropylacrylamide, acrylic acid, fumaric acid, maleic acid, and itaconic acid. Examples of the polymerizable monomer having a basic substituent include allylamine and dimethylaminopropylacrylamide, and examples of the polymerizable monomer having an acidic substituent include acrylic acid, fumaric acid, maleic acid, and itaconic acid. be able to. As long as at least these polymerizable monomers are contained, they may be polymerized alone or may be copolymerized with other polymerizable monomers.

Moreover, as a synthetic resin, what introduce | transduced the basic substituent or the acidic substituent into the synthetic resin which does not have both a basic substituent and an acidic substituent can also be used. In this case, examples of the synthetic resin having neither a basic substituent nor an acidic substituent include a polyolefin resin, a polyester resin, an acrylic resin, a styrene- (meth) acrylate copolymer resin, a urethane resin, and a polyvinyl resin. Alcohol (PVA) resin, polyethylene glycol (PEG) resin, etc. can be mentioned.
The basic substituent can be introduced, for example, by reduction after a cyanation reaction subsequent to halogenation. Moreover, an acidic substituent can be introduce | transduced by hydrolyzing after the cyanation reaction following ozone oxidation, esterification with a dicarboxylic anhydride, and halogenation, for example.

  When the zwitterionic fiber is, for example, a fiber containing a cellulose fiber having an acidic substituent and a synthetic resin having a basic substituent, the cellulose fiber having an acidic substituent has a charge and a basic substituent. By attracting the charge of the synthetic resin, at least one molecule of the synthetic resin is adsorbed on the surface of one cellulose fiber, thereby forming one fiber. In addition, when the zwitterionic fiber is a fiber including a cellulose fiber having an acidic substituent and a cellulose fiber having a basic substituent, at least one cellulose fiber has a surface having one acidic substituent. Cellulose fibers having a basic substituent are entangled, and the acidic substituent and the basic substituent are adsorbed to form a fiber composite.

  Here, whether the fiber is zwitterionic can be determined by, for example, bringing the aqueous solution containing an inorganic salt into contact with the fiber and measuring the electrical conductivity of the aqueous solution containing the inorganic salt before and after contacting the fiber. For example, when cellulose fiber is used as the first polymer and a synthetic resin is used as the second polymer, and the synthetic resin is not sufficiently adsorbed on the surface of the cellulose fiber, the aqueous solution contains an inorganic salt. When released into the solution, the electrical conductivity of the aqueous solution containing the inorganic salt does not decrease at least. In other words, in order to reduce the electrical conductivity of the aqueous solution containing the inorganic salt aqueous solution, both the cation and the anion constituting the inorganic salt need to be trapped in the fiber. It must have ionicity. For this reason, it can be discriminate | determined whether the fiber has zwitterionicity by determining the presence or absence of the fall of the electrical conductivity of the aqueous solution containing inorganic salt.

  The zwitterionic fiber of the present invention includes a natural polymer having an acidic substituent or a basic substituent, and a polymer having an acidic substituent or a basic substituent having a charge opposite to that of the natural polymer. It is a fiber, and one fiber has amphoteric ion exchange ability. For this reason, the zwitterionic fiber can exhibit the zwitterion exchange ability even if it does not contain other constituents (for example, ion exchange resin etc.) other than the zwitterionic fiber. Since the zwitterionic fiber does not need to contain other constituents other than the zwitterionic fiber, when the sheet is formed from the zwitterionic fiber, the thickness of the sheet can be easily adjusted. Moreover, the surface property becomes smooth and the tactile sensation can be improved. Furthermore, in the zwitterionic fiber of the present invention, since the natural polymer and the polymer are adsorbed by electric charges, the release of only one of the substituents is suppressed.

  Moreover, in this invention, ion adsorption property can also be adjusted by controlling the content of the cellulose fiber which has an acidic substituent contained in zwitterionic fiber, and the synthetic resin which has a basic substituent. For example, the ratio between the cellulose fiber and the synthetic resin is preferably 200: 1 to 10: 1 by mass ratio.

  In the present invention, when the zwitterionic fiber is brought into contact with the inorganic salt aqueous solution, the electrical conductivity of the inorganic salt aqueous solution is decreased before and after the contact. This means that the zwitterionic fiber of the present invention has the ability to adsorb both cations and anions. In the present invention, the electric conductivity (μS / cm) of the inorganic salt aqueous solution before contacting with the zwitterionic fiber is P, and 0.01 mmol / g with respect to 1 part by mass (absolute dry mass) of the zwitterionic fiber. 110 parts by mass of an aqueous inorganic salt solution, and after stirring and mixing for 3 minutes, when the electrical conductivity (μS / cm) of the filtrate obtained by solid-liquid separation by filtration is Q, the value of Q / P is 0.95 or less, more preferably 0.90 or less, and even more preferably 0.85 or less. The lower limit value of the Q / P value is not particularly limited, and may be 0.

(Cellulose fiber)
The zwitterionic fiber of the present invention has a natural polymer as a base material. The natural polymer is preferably a cellulose fiber. The polymer may be a natural polymer (second natural polymer), and in this case, may be a cellulose fiber.

  Although it does not specifically limit as a cellulose raw material for obtaining a cellulose fiber, It is preferable to use a pulp from the point that it is easy to acquire and it is cheap. Examples of the pulp include wood pulp, non-wood pulp, and deinked pulp. Examples of wood pulp include hardwood kraft pulp (LBKP), softwood kraft pulp (NBKP), sulfite pulp (SP), dissolved pulp (DP), soda pulp (AP), unbleached kraft pulp (UKP), oxygen bleached craft Chemical pulps such as pulp (OKP) are listed. Moreover, semi-chemical pulps such as semi-chemical pulp (SCP) and chemi-ground wood pulp (CGP), mechanical pulps such as ground wood pulp (GP), thermomechanical pulp (TMP, BCTMP) and the like can be mentioned, but are not particularly limited. Non-wood pulp includes cotton pulp such as cotton linter and cotton lint, non-wood pulp such as hemp, straw and bagasse, cellulose isolated from sea squirts and seaweed, chitin, chitosan, etc., but is not particularly limited. . The deinking pulp includes deinking pulp made from waste paper, but is not particularly limited. The pulp of this embodiment may be used alone or in combination of two or more. Among the above pulps, wood pulp containing cellulose and deinked pulp are preferable in terms of availability.

  The fiber width of the cellulose fiber is not particularly limited. For example, the fiber width of the cellulose fiber may be larger than 1000 nm, or 1000 nm or less. Moreover, the cellulose fiber whose fiber width is larger than 1000 nm and the cellulose fiber whose fiber width is 1000 nm or less may be mixed. In addition, when the fiber width of a cellulose fiber is 1000 nm or less, such a cellulose fiber may be called a fine fibrous cellulose.

  Here, the fiber width of the cellulose fiber can be measured by the following method by observation with an electron microscope. First, a cellulose fiber aqueous suspension having a concentration of 0.05% by mass or more and 0.1% by mass or less is prepared, and the suspension is cast on a carbon film-coated grid subjected to a hydrophilic treatment to obtain a sample for TEM observation. . At this time, an SEM image of the surface cast on glass may be observed. Observation with an electron microscope image is performed at a magnification of 1000 times, 5000 times, 10000 times, or 50000 times depending on the width of the constituent fibers. However, the sample, observation conditions, and magnification are adjusted to satisfy the following conditions.

(1) One straight line X is drawn at an arbitrary location in the observation image, and 20 or more fibers intersect the straight line X.
(2) A straight line Y perpendicular to the straight line is drawn in the same image, and 20 or more fibers intersect the straight line Y.

  The width of the fiber that intersects with the straight line X and the straight line Y is visually read from the observation image that satisfies the above conditions. In this way, at least three sets of images of the surface portion that do not overlap each other are observed, and the width of the fiber intersecting with the straight line X and the straight line Y is read for each image. Thus, at least 20 × 2 × 3 = 120 fiber widths are read.

  Although the average fiber length of a cellulose fiber is not specifically limited, It is preferable that it is 0.1 mm or more, and it is more preferable that it is 0.6 mm or more. Moreover, it is preferable that it is 50 mm or less, and it is more preferable that it is 20 mm or less. Here, the average fiber length of the cellulose fiber can be determined by measuring the length-weighted average fiber length using, for example, a Kajaani fiber length measuring instrument (FS-200 type) manufactured by Kajaani Automation. Moreover, it can also measure using a scanning microscope (SEM), a transmission electron microscope (TEM), etc. according to the length of a fiber.

When the cellulose fiber is fine fibrous cellulose, the fine fibrous cellulose preferably has an I-type crystal structure. Here, the fact that the fine fibrous cellulose has a type I crystal structure can be identified in a diffraction profile obtained from a wide-angle X-ray diffraction photograph using CuKα (λ = 1.5418Å) monochromatized with graphite. Specifically, it can be identified by having typical peaks at two positions of 2θ = 14 ° to 17 ° and 2θ = 22 ° to 23 °.
The proportion of the I-type crystal structure in the fine fibrous cellulose is preferably 30% or more, more preferably 50% or more, and further preferably 70% or more. In this case, further superior performance can be expected in terms of heat resistance and low linear thermal expansion coefficient. The degree of crystallinity is obtained by measuring an X-ray diffraction profile and determining the crystallinity by a conventional method (Seagal et al., Textile Research Journal, 29, 786, 1959).

<Cellulose fiber having a phosphate group>
When the cellulose fiber has a phosphate group, the phosphate group can be introduced into the cellulose fiber through a phosphate group introduction step. In the phosphoric acid group introduction step, at least one selected from a phosphoric acid group or a compound having a substituent derived from a phosphoric acid group and a salt thereof (hereinafter referred to as “phosphorating agent” or “compound A”) is used for the cellulose fiber. Can be performed by reacting. Such a phosphorylating agent may be mixed in dry or wet cellulose fibers in the form of powder or aqueous solution. As another example, a phosphoric acid powder or an aqueous solution may be added to the cellulose fiber slurry. That is, the phosphate group introduction step includes at least a step of mixing the cellulose fiber and the phosphorylating agent.

  The phosphate group introduction step can be performed by reacting a cellulose fiber with a phosphorylating agent. This reaction is performed by at least one selected from urea and derivatives thereof (hereinafter also referred to as “compound B”). You may carry out in presence.

  As an example of a method for causing compound A to act on cellulose fibers in the presence of compound B, a method of mixing powder or aqueous solution of compound A and compound B with cellulose fibers in a dry state or a wet state can be mentioned. Another example is a method of adding powders and aqueous solutions of Compound A and Compound B to the cellulose fiber-containing slurry. Among these, since the uniformity of the reaction is high, a method of adding an aqueous solution of Compound A and Compound B to dry cellulose fibers, or a powder or an aqueous solution of Compound A and Compound B to wet cellulose fibers The method is preferred. Moreover, the compound A and the compound B may be added simultaneously, or may be added separately. Moreover, you may add the compound A and the compound B first used for reaction as aqueous solution, and remove an excess chemical | medical solution by pressing. The form of the cellulose fiber is preferably cotton or thin sheet, but is not particularly limited.

  The phosphorylating agent (compound A) is at least one selected from a compound having a phosphate group and a salt thereof. Examples of the compound having a phosphate group include, but are not limited to, phosphoric acid, lithium salt of phosphoric acid, sodium salt of phosphoric acid, potassium salt of phosphoric acid, ammonium salt of phosphoric acid, and the like. Examples of the lithium salt of phosphoric acid include lithium dihydrogen phosphate, dilithium hydrogen phosphate, trilithium phosphate, lithium pyrophosphate, and lithium polyphosphate. Examples of the sodium salt of phosphoric acid include sodium dihydrogen phosphate, disodium hydrogen phosphate, trisodium phosphate, sodium pyrophosphate, and sodium polyphosphate. Examples of the potassium salt of phosphoric acid include potassium dihydrogen phosphate, dipotassium hydrogen phosphate, tripotassium phosphate, potassium pyrophosphate, and potassium polyphosphate. Examples of the ammonium salt of phosphoric acid include ammonium dihydrogen phosphate, diammonium hydrogen phosphate, triammonium phosphate, ammonium pyrophosphate, and ammonium polyphosphate. Among these, phosphoric acid, sodium salt of phosphoric acid, potassium salt of phosphoric acid, and ammonium salt of phosphoric acid are preferably used.

  The phosphorylating agent (compound A) is preferably used as an aqueous solution because the uniformity of the reaction is increased and the efficiency of introducing a phosphate group is further increased. The pH of the aqueous solution of the phosphorylating agent (compound A) is not particularly limited, but is preferably 7 or less because the efficiency of introduction of phosphoric acid groups is increased, and pH 3 or more and pH 7 or less from the viewpoint of suppressing hydrolysis of cellulose fibers. Is more preferable. The pH of the aqueous solution of Compound A may be adjusted by, for example, using a phosphoric acid group-containing compound that exhibits acidity and an alkalinity, and changing the amount ratio thereof. You may adjust pH of the aqueous solution of a phosphorylating agent (compound A) by adding an inorganic alkali or an organic alkali to what shows acidity among the compounds which have a phosphoric acid group.

  Although the addition amount of the phosphorylating agent (compound A) with respect to a cellulose fiber is not specifically limited, When the addition amount of a phosphorylating agent (compound A) is converted into a phosphorus atomic weight, the addition amount of the phosphorus atom with respect to a cellulose fiber (absolute dry mass) Is preferably 0.5 to 100% by mass, more preferably 1 to 50% by mass, and most preferably 2 to 30% by mass. If the addition amount of the phosphorus atom with respect to a cellulose fiber is in the said range, the yield of a phosphorylated cellulose fiber can be improved more. By making the addition amount of phosphorus atoms to the cellulose fiber 100% by mass or less, it is possible to balance the effect of improving the yield and the cost. On the other hand, a yield can be raised by making the addition amount of the phosphorus atom with respect to a cellulose fiber more than the said lower limit.

  Examples of the compound B used in this embodiment include urea, biuret, 1-phenylurea, 1-benzylurea, 1-methylurea, 1-ethylurea and the like.

  Compound B is preferably used as an aqueous solution in the same manner as Compound A. Moreover, since the uniformity of reaction increases, it is preferable to use the aqueous solution in which both compound A and compound B are dissolved. The amount of Compound B added to the cellulose fiber (absolute dry mass) is preferably 1% by mass or more and 500% by mass or less, more preferably 10% by mass or more and 400% by mass or less, and 100% by mass or more and 350% by mass or less. More preferably, it is more preferably 150% by mass or more and 300% by mass or less.

  In addition to Compound A and Compound B, amides or amines may be included in the reaction system. Examples of amides include formamide, dimethylformamide, acetamide, dimethylacetamide and the like. Examples of amines include methylamine, ethylamine, trimethylamine, triethylamine, monoethanolamine, diethanolamine, triethanolamine, pyridine, ethylenediamine, hexamethylenediamine, and the like. Among these, triethylamine is known to work as a good reaction catalyst.

  The phosphate group introduction step preferably includes a heating step (hereinafter also referred to as a heat treatment step). By providing the heat treatment step, a phosphate group can be efficiently introduced into the cellulose fiber, and at least a part of the phosphate group or a substituent derived from the phosphate group can be crosslinked. That is, it is preferable that the manufacturing method of the composition of this invention includes the process of mixing a cellulose fiber and a phosphorylating agent, and the process of heating the mixture of a cellulose fiber and a phosphorylating agent.

  As the heat treatment temperature in the heat treatment step, it is preferable to select a temperature at which phosphate groups can be efficiently introduced while suppressing thermal decomposition and hydrolysis reaction of cellulose fibers. Specifically, the heat treatment temperature is preferably 50 ° C. or higher and 300 ° C. or lower, more preferably 100 ° C. or higher and 250 ° C. or lower, and further preferably 130 ° C. or higher and 200 ° C. or lower. Moreover, you may use a vacuum dryer, an infrared heating apparatus, and a microwave heating apparatus for a heating.

  During the heat treatment, while water is contained in the cellulose fiber-containing slurry to which compound A has been added, if the time for which the cellulose fibers are allowed to stand is increased, the compound A that dissolves with water molecules along with the drying is deposited on the cellulose fiber surface. Moving. Therefore, the concentration of the compound A in the cellulose fiber may be uneven, and the introduction of phosphate groups on the surface of the cellulose fiber may not proceed uniformly. In order to suppress the occurrence of uneven density of Compound A in the cellulose fiber due to drying, a very thin sheet-like cellulose fiber is used, or the cellulose fiber and Compound A are kneaded or stirred with a kneader or the like and dried by heating or drying under reduced pressure. The method should be taken.

  The heating device used for the heat treatment is preferably a device that can always discharge the moisture retained by the slurry and the moisture generated by the addition reaction of the fibers such as phosphate groups to the hydroxyl group of the fiber, such as a blower oven. Etc. are preferred. If the moisture in the system is always discharged, the hydrolysis reaction of the phosphate ester bond, which is the reverse reaction of the phosphorylation, can be suppressed, and the acid hydrolysis of the sugar chain in the cellulose fiber can be suppressed. it can.

  The heat treatment time is also affected by the heating temperature, but it is preferably 1 second or more and 300 minutes or less, more preferably 1 second or more and 1000 seconds or less after moisture is substantially removed from the pulp slurry. More preferably, it is 10 seconds or more and 800 seconds or less. In the present invention, the amount of phosphate groups introduced can be within a preferred range by setting the heating temperature and the heating time to appropriate ranges.

  The phosphate group introduction step may be performed at least once, but may be repeated a plurality of times. In this case, more phosphoric acid groups are introduced, which is preferable. For example, it is also a preferable aspect to perform the phosphate group introduction step twice.

  The phosphoric acid group content of the cellulose fiber is preferably 0.10 mmol / g or more, more preferably 0.20 mmol / g or more, and 0.50 mmol / g or more per 1 g (mass) of cellulose fibers. It is more preferable that it is 1.00 mmol / g or more. Moreover, it is preferable that content of a phosphoric acid group is 3.65 mmol / g or less, It is more preferable that it is 3.50 mmol / g or less, It is further more preferable that it is 3.00 mmol / g or less. In addition, in this specification, content of the phosphate group which a cellulose fiber has is equal to the strongly acidic group amount of the phosphate group which a cellulose fiber has so that it may mention later.

  The phosphate group content of the cellulose fiber can be measured by a conductivity titration method. In the measurement by the conductivity titration method, after completely converting the phosphate group to the acid form, it is refined by a mechanical treatment process (a refinement process), and the resulting fine fibrous cellulose-containing slurry is The amount introduced is determined by determining the change in pH while adding aqueous sodium hydroxide.

  The phosphoric acid group is converted into an acid form by diluting the obtained phosphorylated cellulose fiber with ion-exchanged water so that the cellulose fiber concentration becomes 2% by mass, and stirring a sufficient amount of 1N aqueous hydrochloric acid solution. This is done by adding them one by one. In the conversion of the phosphoric acid group into an acid form, the cellulose fiber-containing slurry is dehydrated to obtain a dehydrated sheet, which is then diluted again with ion-exchanged water, and the operation of adding a 1N aqueous hydrochloric acid solution is repeated, thereby producing cellulose fibers. It is preferable to completely change the phosphate group contained in the acid form. Then, after the step of converting the phosphoric acid group into an acid form, the obtained cellulose fiber-containing slurry is stirred and dispersed uniformly, and then the operation of obtaining a dehydrated sheet by filtration and dehydration is repeated, so that surplus It is preferable to wash away hydrochloric acid sufficiently.

  In the mechanical treatment process (miniaturization process), ion-exchanged water is poured into the obtained dehydration sheet to obtain a cellulose fiber-containing slurry having a cellulose fiber concentration of 0.3% by mass. Using Cleamix-2.2S manufactured by Technic Co., Ltd., treatment is performed for 30 minutes at 21500 rpm. In this way, a fine fibrous cellulose-containing slurry is obtained.

  In titration using an alkali, a change in pH value indicated by the dispersion is measured while adding a 0.1N aqueous sodium hydroxide solution to the fine fibrous cellulose-containing slurry. This neutralization titration gives two points where the increment (differential value of pH with respect to the amount of alkali dropped) is maximized in the curve plotting the measured pH against the amount of alkali (aqueous sodium hydroxide solution) added ( The point where the increment is the largest and the second largest point). Of these, the amount of alkali required up to the maximum incremental point (hereinafter referred to as the first end point) obtained for the first time after adding alkali is equal to the amount of strongly acidic group in the dispersion used for titration. The amount of alkali required up to the maximum point of increment obtained (hereinafter referred to as the second end point) is equal to the amount of weakly acidic groups in the dispersion used for titration. The alkali amount (mmol) required up to the first end point is divided by the solid content (g) in the fine fibrous cellulose-containing slurry to be titrated to obtain the first dissociated alkali amount (mmol / g). Is the phosphate group content of the cellulose fiber.

  FIG. 1 shows an example of a curve plotting measured pH against the amount of alkali (sodium hydroxide aqueous solution) added in neutralization titration. The region up to the first end point is referred to as the first region, and the region up to the second end point is referred to as the second region. There is a third region after the second region. That is, three areas appear. In FIG. 1, the amount of alkali required in the first region is equal to the amount of strongly acidic groups in the slurry used for titration, and the amount of alkali required in the second region is the amount of weakly acidic groups in the slurry used for titration. Is equal to

<Cellulose fiber having a carboxyl group>
When the cellulose fiber has a carboxyl group, the carboxyl group can be introduced into the cellulose fiber through a carboxyl group introduction step. In the carboxyl group introduction step, the carboxyl fiber is introduced into the cellulose fiber by treating the cellulose fiber with an oxidation treatment such as TEMPO oxidation treatment or a compound having a carboxylic acid-derived group, its derivative, or its acid anhydride or its derivative. can do.

  The compound having a carboxyl group is not particularly limited, and examples thereof include dicarboxylic acid compounds such as maleic acid, succinic acid, phthalic acid, fumaric acid, glutaric acid, adipic acid and itaconic acid, and tricarboxylic acid compounds such as citric acid and aconitic acid. .

  The acid anhydride of the compound having a carboxyl group is not particularly limited, but examples thereof include acid anhydrides of dicarboxylic acid compounds such as maleic anhydride, succinic anhydride, phthalic anhydride, glutaric anhydride, adipic anhydride, and itaconic anhydride. It is done.

  Although it does not specifically limit as a derivative of the compound which has a carboxyl group, The derivative of the acid anhydride of the compound which has a carboxyl group and the acid anhydride imidation of a compound which has a carboxyl group are mentioned. Although it does not specifically limit as an acid anhydride imidation thing of a compound which has a carboxyl group, Imidation thing of dicarboxylic acid compounds, such as maleimide, succinic acid imide, and phthalic acid imide, is mentioned.

  The acid anhydride derivative of the compound having a carboxyl group is not particularly limited. For example, at least some of the hydrogen atoms of the acid anhydride of the compound having a carboxyl group, such as dimethylmaleic anhydride, diethylmaleic anhydride, diphenylmaleic anhydride, etc. are substituted (for example, alkyl group, phenyl group, etc. ) Are substituted.

  The amount of carboxyl groups introduced is preferably 0.10 mmol / g or more per 1 g (mass) of cellulose fibers, more preferably 0.20 mmol / g or more, and further preferably 0.50 mmol / g or more. It is particularly preferably 1.00 mmol / g or more. The amount of carboxyl group introduced is preferably 3.65 mmol / g or less, more preferably 3.50 mmol / g or less, and further preferably 3.00 mmol / g or less.

  The amount of carboxyl group introduced can be measured by a conductivity titration method. When measuring by the conductivity titration method, the mechanical treatment process (miniaturization process) is performed, and the change in conductivity is calculated while adding an aqueous sodium hydroxide solution to the obtained fine fibrous cellulose-containing slurry. Measure the amount introduced. The mechanical processing step (miniaturization step) is the same as the step performed when measuring the introduction amount of phosphate groups.

  In the conductivity titration method, the curve shown in FIG. 2 is given when alkali is added. This curve is divided into a first region until the conductivity increment (slope) becomes substantially constant after the electrical conductivity decreases, and then a second region where the conductivity increment (slope) increases. Note that the boundary point between the first region and the second region is defined as the point at which the amount of change in conductivity twice, that is, the increase (inclination) in conductivity is maximized. The alkali amount (mmol) required in the first region of the curve shown in FIG. 2 is divided by the solid content (g) in the fine fibrous cellulose-containing slurry to be titrated, and the amount of carboxyl group introduced (mmol / g).

<Cellulose fiber having a basic substituent>
When the cellulose fiber has a basic substituent, the basic substituent can be introduced into the cellulose fiber through a basic substituent introduction step. In the basic substituent introduction step, a basic substituent can be introduced by adding a cationizing agent and an alkali compound to the cellulose fiber and reacting them.

  As the cationizing agent, a cationizing agent having a quaternary ammonium group and a group that reacts with the hydroxyl group of cellulose is preferably used. Examples of the group that reacts with the hydroxyl group of cellulose include an epoxy group, a functional group having a halohydrin structure, a vinyl group, and a halogen group. Specific examples of the cationizing agent include glycidyltrialkylammonium halides such as glycidyltrimethylammonium chloride and 3-chloro-2-hydroxypropyltrimethylammonium chloride or halohydrin type compounds thereof.

  The alkali compound contributes to the promotion of the cationization reaction. Alkali compounds include alkali metal hydroxides or alkaline earth metal hydroxides, alkali metal carbonates or alkaline earth metal carbonates, alkali metal phosphates or alkaline earth metal phosphates, etc. Organic alkali compounds such as ammonia, aliphatic amines, aromatic amines, aliphatic ammoniums, aromatic ammoniums, heterocyclic compounds and their hydroxides, carbonates, phosphates, etc. It may be. The amount of basic substituent introduced can be measured using elemental analysis such as trace nitrogen analysis.

<Defibration processing>
When the natural polymer in the present invention is fine fibrous cellulose having a fiber width of 1000 nm or less, it is preferable to provide a defibrating treatment step. In the defibrating process, the fiber is usually defibrated using a defibrating apparatus to obtain a fine fibrous cellulose-containing slurry, but the processing apparatus and the processing method are not particularly limited.
As the defibrating apparatus, a high-speed defibrator, a grinder (stone mill type pulverizer), a high-pressure homogenizer, an ultra-high pressure homogenizer, a high-pressure collision type pulverizer, a ball mill, a bead mill, or the like can be used. Alternatively, as a defibrating apparatus, a device for wet grinding such as a disk type refiner, a conical refiner, a twin-screw kneader, a vibration mill, a homomixer under high-speed rotation, an ultrasonic disperser, or a beater should be used. You can also. The defibrating apparatus is not limited to the above. Preferable defibrating treatment methods include a high-speed defibrator, a high-pressure homogenizer, and an ultra-high pressure homogenizer that are less affected by the grinding media and less worried about contamination.

<Alkali treatment process>
An alkali treatment step may be provided before the defibration treatment step described above. Although it does not specifically limit as a method of an alkali treatment, For example, the method of immersing a phosphorylated cellulose fiber in an alkaline solution is mentioned.

  The alkali compound contained in the alkali solution is not particularly limited, but may be an inorganic alkali compound or an organic alkali compound. The solvent in the alkaline solution may be either water or an organic solvent. The solvent is preferably a polar solvent (polar organic solvent such as water or alcohol), and may be an aqueous solvent. Of the alkaline solutions, a sodium hydroxide aqueous solution or a potassium hydroxide aqueous solution is particularly preferred because of its high versatility.

Although the temperature of the alkali solution in an alkali treatment process is not specifically limited, 5 to 80 degreeC is preferable and 10 to 60 degreeC is more preferable.
The immersion time in the alkaline solution in the alkali treatment step is not particularly limited, but is preferably 5 minutes or longer and 30 minutes or shorter, and more preferably 10 minutes or longer and 20 minutes or shorter.
Although the usage-amount of the alkaline solution in an alkali treatment is not specifically limited, It is preferable that it is 100 mass% or more and 100,000 mass% or less with respect to the absolute dry mass of a phosphorylated cellulose fiber, and it is 1000 mass% or more and 10000 mass% or less. Is more preferable.

(Synthetic polymer)
<Synthetic resin having a basic substituent>
A synthetic resin having a basic substituent can be obtained by polymerizing a polymerizable monomer having a basic substituent. For example, a synthetic resin having a basic substituent may be synthesized by polymerizing allylamine or dimethylaminopropylacrylamide.

  Moreover, the synthetic resin which has a basic substituent can also be obtained by introduce | transducing a basic substituent into the synthetic resin which does not have both a basic substituent and an acidic substituent. In this case, examples of the synthetic resin having neither a basic substituent nor an acidic substituent include a polyolefin resin, a polyester resin, an acrylic resin, a styrene- (meth) acrylate copolymer resin, a urethane resin, and a polyvinyl resin. Alcohol (PVA) resin, polyethylene glycol (PEG) resin, etc. can be mentioned. And a basic substituent can be introduce | transduced into such a synthetic resin by reducing after the cyanation reaction following halogenation, for example.

<Synthetic resin having an acidic substituent>
A synthetic resin having an acidic substituent can be obtained by polymerizing a polymerizable monomer having an acidic substituent. For example, a synthetic resin having an acidic substituent may be synthesized by polymerizing acrylic acid, fumaric acid, maleic acid, and itaconic acid.

  Moreover, the synthetic resin which has an acidic substituent can also be obtained by introduce | transducing an acidic substituent into the synthetic resin which does not have both a basic substituent and an acidic substituent. Examples of the synthetic resin that does not have both a basic substituent and an acidic substituent include the resins described above. And an acidic substituent can be introduce | transduced into the said synthetic resin by hydrolyzing after the cyanation reaction following ozone oxidation, esterification with a dicarboxylic anhydride, and halogenation, for example.

(Method for producing amphoteric fibers)
The method for producing the zwitterionic fiber of the present invention has a natural polymer having an acidic substituent or a basic substituent, and an acidic substituent or basic substituent having a charge opposite to that of the natural polymer. And a step of mixing the polymer (mixing step).

  In the present invention, when the natural polymer has an acidic substituent, it is preferable to convert the salt form of the acidic substituent into an H-type. That is, in H-type conversion, the counter ion of the acidic substituent is converted to a hydrogen ion. In the present invention, such a process can also be called a salt type conversion process. The salt type conversion step is preferably provided before the mixing step.

  In the salt type conversion step, an acidic solution such as hydrochloric acid is added to the natural polymer-containing slurry having an acidic substituent. At this time, it is preferable to add the acidic solution so that the natural polymer-containing slurry has a pH of 2 or more and 3 or less. After the salt type conversion step, the natural polymer-containing slurry is dehydrated to obtain a dehydrated sheet, and then the process of pouring ion-exchanged water again and stirring to uniformly disperse the natural polymer is performed. Is preferred. Further, it is preferable to repeat the addition and washing of the acidic solution until the salt type is sufficiently changed.

  When the natural polymer has a basic substituent, it is preferable to convert the salt form of the basic substituent to the OH type. That is, the counter ion of the basic substituent is preferably a hydroxide ion. In the present invention, such a process is also called a salt type conversion process. The salt type conversion step is preferably provided before the mixing step.

  In the salt type conversion step, a basic solution such as a sodium hydroxide solution is added to the natural polymer-containing slurry having a basic substituent. At this time, it is preferable to add a basic solution so that the natural polymer-containing slurry has a pH of 11 or more and 12 or less. After the salt type conversion step, the natural polymer-containing slurry is dehydrated to obtain a dehydrated sheet, and then the process of pouring ion-exchanged water again and stirring to uniformly disperse the natural polymer is performed. Is preferred. Further, it is preferable to repeat the addition and washing of the basic solution until the salt type is sufficiently changed.

  In a step of mixing a natural polymer having an acidic substituent or a basic substituent with a polymer having an acidic substituent or a basic substituent having a charge opposite to that of the natural polymer (mixing step) The polymer having an acidic substituent or a basic substituent is added to the slurry containing the natural polymer obtained through the salt-type conversion step and stirred. In addition, when adding the polymer which has an acidic substituent or a basic substituent, it is preferable to add a polymer in the state of solutions, such as a slurry.

  After the mixing step, the slurry may be dehydrated to obtain a dehydrated sheet, and then a drying step may be provided. In the drying step, drying is preferably performed at a temperature of 20 ° C. or higher and 100 ° C. or lower. The present invention may relate to a sheet made of zwitterionic fibers. Through the above steps, both the natural polymer having an acidic substituent or a basic substituent and the polymer having an acidic substituent or a basic substituent having a charge opposite to that of the natural polymer are included. An ionic fiber is obtained.

  In the mixing step, a natural polymer having an acidic substituent or a basic substituent is mixed with an optional component other than a polymer having an acidic substituent or a basic substituent having a charge opposite to that of the natural polymer. May be. Optional components include, for example, defoaming agents, lubricants, surfactants, UV absorbers, dyes, pigments, fillers, stabilizers, organic solvents miscible with water such as alcohol, preservatives, organic fine particles, and inorganic fine particles. , Resin (pellet, fiber) and the like.

(Use)
The zwitterionic fiber of the present invention may be dispersed in a slurry. Moreover, you may form a sheet | seat (for example, a nonwoven fabric, a filter, a laminated body etc.) and a granular material (for example, bead, granule etc.) from the zwitterionic fiber of this invention. By using the zwitterionic fiber of the present invention, ion exchange and desalting can be performed. The zwitterionic fiber of the present invention is useful as an ion exchange fiber.

  Moreover, you may form a molded object by heat-pressing the sheet | seat containing the zwitterionic fiber of this invention. In this case, ion exchange and desalting can be performed without adding a filler such as an ion exchange resin.

  Furthermore, the sheet or granular material containing the zwitterionic fiber of the present invention is used, for example, as an absorbent (diaper or the like) for sweat, urine, menstrual blood, etc., and to increase the water absorption of a water absorbent material such as SAP. It can also be used as a pretreatment material.

  The features of the present invention will be described more specifically with reference to examples and comparative examples. The materials, amounts used, ratios, processing details, processing procedures, and the like shown in the following examples can be changed as appropriate without departing from the spirit of the present invention. Therefore, the scope of the present invention should not be construed as being limited by the specific examples shown below.

(Production Example 1)
<Introduction of phosphate group>
Oji Paper's pulp (solid content: 93 mass%, basis weight: 208 g / m ² sheet, Canadian standard freeness (CSF) measured according to JIS P 8121 is 700 ml) is used as softwood kraft pulp did. 100 parts by mass of the above softwood kraft pulp (absolutely dry mass) is impregnated with a mixed aqueous solution of ammonium dihydrogen phosphate and urea, and compressed to 45 parts by mass of ammonium dihydrogen phosphate and 120 parts by mass of urea, and impregnated with chemicals Pulp was obtained. The obtained chemical-impregnated pulp was dried and heat-treated for 200 seconds with a hot air dryer at 165 ° C. to introduce phosphoric acid groups into cellulose in the pulp to obtain phosphorylated pulp (phosphorylated cellulose fiber).

<Washing of phosphorylated pulp>
Pour 10000 parts by mass of ion-exchanged water with respect to 100 parts by mass of the resulting phosphorylated pulp (absolutely dry mass), stir and disperse uniformly, then filter and dehydrate to obtain a dehydrated sheet twice. Repeatedly, a dehydrated sheet A of phosphorylated pulp was obtained. In the dehydration sheet A, the introduction amount of phosphate groups determined by a titration method described later was 1.1 mmol / g.

<Measurement of phosphate group introduction amount>
The amount of phosphate group introduced was measured by neutralization titration. Specifically, after the phosphoric acid group contained in phosphorylated pulp (phosphorylated cellulose fiber) is completely converted into an acid form, it is refined by a mechanical treatment process (a refinement process), and the obtained fine fiber The amount of introduction was measured by determining the change in pH indicated by the slurry (dispersion) while adding 0.1N aqueous sodium hydroxide to the slurry containing cellulose.
In converting the phosphoric acid group into an acid form, the obtained phosphorylated cellulose fiber is diluted with ion-exchanged water so that the cellulose fiber concentration becomes 2% by mass, and a sufficient amount of 1N hydrochloric acid aqueous solution is slightly added while stirring. Added in increments. Next, the cellulose fiber-containing slurry is stirred for 15 minutes and then dehydrated to obtain a dehydrated sheet. Then, the slurry is diluted again with ion-exchanged water, and a 1N hydrochloric acid aqueous solution is added to repeat the phosphoric acid contained in the cellulose fiber. The group was completely changed to the acid form. Furthermore, the cellulose fiber-containing slurry was stirred and dispersed uniformly, and then the operation of obtaining a dehydrated sheet by filtration and dehydration was repeated to sufficiently wash away excess hydrochloric acid.
In the mechanical treatment process, ion-exchanged water was poured into the obtained dehydration sheet to obtain a cellulose fiber-containing slurry having a cellulose fiber concentration of 0.3% by mass. This slurry was processed for 30 minutes under the condition of 21500 rotations / minute using a defibrating apparatus (Cleamix-2.2S, manufactured by M Technique Co., Ltd.). In the titration using an alkali, a change in pH value indicated by the dispersion was measured while adding a 0.1N sodium hydroxide aqueous solution to the fine fibrous cellulose-containing slurry.

This neutralization titration gives two points where the increment (differential value of pH with respect to the amount of alkali dropped) is maximized in the curve plotting the measured pH against the amount of alkali added (the point at which the increment is maximum). And the second largest point). Of these, the amount of alkali required up to the maximum point of increment obtained first after adding alkali (hereinafter referred to as the first end point) is equal to the amount of strongly acidic groups in the dispersion used for titration, The amount of alkali required up to the maximum point of increase obtained (hereinafter referred to as the second end point) becomes equal to the amount of weakly acidic groups in the dispersion used for titration.
The alkali amount (mmol) required up to the first end point is divided by the solid content (g) in the titration target dispersion to obtain the first dissociated alkali amount (mmol / g). The amount introduced.

<Salt type conversion of phosphorylated pulp (H type)>
5000 parts by mass of ion-exchanged water was diluted with respect to 100 parts by mass of the dehydrated sheet A (absolute dry mass) of phosphorylated pulp. Next, 1N hydrochloric acid was added little by little while stirring to obtain a pulp slurry having a pH of 2 or more and 3 or less. Thereafter, the pulp slurry was dehydrated to obtain a dehydrated sheet, and then ion-exchanged water was poured again, and the mixture was stirred and dispersed uniformly. Subsequently, the operation of obtaining a dehydrated sheet by filtration and dehydration was repeated to sufficiently wash away excess hydrochloric acid, thereby obtaining phosphorylated pulp (H type).

<Adsorption of basic polymer on phosphorylated pulp (H type)>
5000 parts by mass of ion-exchanged water was diluted with respect to 100 parts by mass of the resulting phosphorylated pulp (H type) (absolute dry mass). Subsequently, polyallylamine (Nitto Bo Medical Co., Ltd., PAA-03, weight average molecular weight 3000, solid content 20% by mass) was added to 100 parts by mass (absolute dry mass) of the pulp while stirring. In that case, it added little by little so that the solid content amount in polyallylamine might be 2.5 mass parts (absolute dry mass). Thereafter, the pulp slurry was dehydrated to obtain a dehydrated sheet, and then ion-exchanged water was poured again, and the mixture was stirred and dispersed uniformly. Subsequently, the operation of obtaining a dehydrated sheet by filtration and dehydration was repeated. Furthermore, after sufficiently replacing the obtained pulp sheet with acetone, it was dried with an explosion-proof dryer at 40 ° C. to obtain polyallylamine (PAA-03) -adsorbed phosphorylated pulp (a zwitterionic fiber).

(Production Example 2)
Production Example 1 except that polyallylamine (manufactured by Nitto Bo Medical Co., Ltd., PAA-08, weight average molecular weight 8000, solid content 15% by mass) was used instead of polyallylamine (manufactured by Nitto Bo Medical Co., Ltd., PAA-03). In the same manner as above, polyallylamine (PAA-08) -adsorbed phosphorylated pulp (a zwitterionic fiber) was obtained.

(Production Example 3)
Production Example 1 except that polyallylamine (Nittobo Medical Co., Ltd., PAA-25, PAA-25, weight average molecular weight 25000, solid content 10 mass%) was used instead of polyallylamine (Nittobo Medical Co., Ltd., PAA-03). In the same manner as above, polyallylamine (PAA-25) -adsorbed phosphorylated pulp (a zwitterionic fiber) was obtained.

(Production Example 4)
<TEMPO oxidation reaction>
Undried softwood bleached kraft pulp equivalent to a dry mass of 100 parts by mass, 1.25 parts by mass of TEMPO (2,2,6,6-tetramethylpiperidine 1-oxyl), 12.5 parts by mass of sodium bromide, It was dispersed in 10,000 parts by mass. Subsequently, 13 mass% sodium hypochlorite aqueous solution was added so that the quantity of sodium hypochlorite might be 3.0 mmol with respect to 1.0 g of pulp, and reaction was started. During the reaction, a 0.5 M aqueous sodium hydroxide solution was added dropwise to maintain the pH at 10 or more and 11 or less, and the reaction was regarded as complete when no change in pH was observed.

<Cleaning of TEMPO oxidized pulp>
Thereafter, this pulp slurry is dehydrated to obtain a dehydrated sheet, and then the process of pouring 5000 parts by mass of ion exchange water, stirring and uniformly dispersing, and dehydrating by filtration to obtain a dehydrated sheet is repeated twice. It was. The introduced amount of carboxyl groups in the obtained TEMPO oxidized pulp (TEMPO oxidized cellulose fiber) was 1.1 mmol / g.

<Salt type conversion of TEMPO oxidized pulp (H type)>
To 100 parts by mass of the obtained dehydrated sheet (absolute dry mass), 5000 parts by mass of ion-exchanged water was added for dilution. Next, 1N hydrochloric acid was added little by little while stirring to obtain a pulp slurry having a pH of 2 or more and 3 or less. Thereafter, the pulp slurry was dehydrated to obtain a dehydrated sheet, and then ion-exchanged water was poured again, and the mixture was stirred and dispersed uniformly. Subsequently, the operation of obtaining a dehydrated sheet by filtration and dehydration was repeated to sufficiently wash away excess hydrochloric acid to obtain TEMPO oxidized pulp (H type).

<Adsorption of basic polymer to TEMPO oxidized pulp (H type)>
To 100 parts by mass of the obtained TEMPO oxidized pulp (H type) (absolute dry mass), 5000 parts by mass of ion-exchanged water was added for dilution. Next, polyallylamine (Nitto Bo Medical Co., Ltd., PAA-08, weight average molecular weight 8000, solid content 15% by mass) was added to 100 parts by mass (absolute dry mass) of the pulp while stirring. In that case, it added little by little so that the solid content amount in polyallylamine might be 2.5 mass parts (absolute dry mass). Thereafter, the pulp slurry was dehydrated to obtain a dehydrated sheet, and then ion-exchanged water was poured again, and the mixture was stirred and dispersed uniformly. Subsequently, the operation of obtaining a dehydrated sheet by filtration and dehydration was repeated. Furthermore, after sufficiently replacing the obtained pulp sheet with acetone, it was dried with an explosion-proof dryer at 40 ° C. to obtain polyallylamine (PAA-08) -adsorbed TEMPO oxidized pulp (a zwitterionic fiber).

(Production Example 5)
<Pulp fluffing>
Cotton-like fluffing pulp obtained by processing a sheet (pulp content 90% by mass) made of softwood bleached kraft pulp (NBKP) for 15 seconds at a rotation speed of 20000 rpm using a hand mixer (manufactured by Osaka Chemical Co., Ltd., Labo Milser PLUS) (Pulp content 90% by mass).

<Cationization reaction>
Next, 100 parts by mass of a cationizing agent (Kachio Master G, manufactured by Yokkaichi Chemical Co., Ltd., glycidyltrimethylammonium chloride, pure content: 73.1% by mass, moisture content: 20.2% by mass) and 1.5N aqueous sodium hydroxide solution 70 The cationizing agent mixed solution mixed with parts by mass is sprayed onto 100 parts by mass of fluffing pulp using a sprayer, placed in a polyvinylidene chloride bag, and the bag is squeezed by hand. The reaction mixture was uniformly permeated into the pulp to prepare a reaction sample.
Then, the air in a bag was removed and it was made to react at 80 degreeC for 1 hour, and the cationized pulp A was obtained.

<Multiple cationization>
To the obtained cationized pulp A, the cationizing pulp B was obtained by adding and reacting the above cationizing agent mixed solution in the same manner.

<Washing of cationized pulp>
5000 parts by mass of ion-exchanged water was added to 100 parts by mass of the obtained cationized pulp B (absolutely dry mass), washed with stirring, and then dehydrated. The washing / dehydration treatment was repeated 4 times to obtain washed cationized pulp. It was 1.1 mmol / g when the amount of cationic groups contained in the washed cationized pulp (cationized cellulose fiber) was measured by a trace nitrogen analysis method.

<Salt type conversion of cationized pulp (OH type)>
5000 parts by mass of ion-exchanged water was diluted with respect to 100 parts by mass of the washed washed cationized pulp (absolute dry mass). Next, a 1N NaOH aqueous solution was added little by little while stirring to obtain a pulp slurry having a pH of 11 or more and 12 or less. Thereafter, the pulp slurry was dehydrated to obtain a dehydrated sheet, and then ion-exchanged water was poured again, and the mixture was stirred and dispersed uniformly. Subsequently, the operation of obtaining a dehydrated sheet by filtration and dehydration was repeated to sufficiently wash away excess sodium hydroxide to obtain a cationized pulp (OH type).

  To 100 parts by mass of the obtained cationized pulp (OH type) (absolute dry mass), 5000 parts by mass of ion exchange water was added for dilution. The slurry which added and diluted 5000 mass parts ion-exchange water to 100 mass parts of the phosphorylated pulp (H type) (absolute dry mass) obtained by manufacture example 1 was added little by little here. Thereafter, the pulp slurry was dehydrated to obtain a dehydrated sheet, and then ion-exchanged water was poured again, and the mixture was stirred and dispersed uniformly. Subsequently, the operation of obtaining a dehydrated sheet by filtration and dehydration was repeated. Furthermore, after fully replacing the obtained pulp sheet with acetone, it was dried with an explosion-proof dryer at 40 ° C. to obtain a phosphorylated pulp-cationized pulp complex (a zwitterionic fiber).

(Examples 1-5)
110 parts by mass of 0.01 mmol / g calcium chloride aqueous solution is added to 1 part by mass (absolute dry mass) of the pulp obtained in Production Examples 1 to 5, and after stirring and mixing for 3 minutes, solid-liquid separation is performed by filtration. went. Under the present circumstances, the electrical conductivity of the calcium chloride aqueous solution before making a pulp and calcium chloride aqueous solution contact, and the electrical conductivity of the calcium chloride aqueous solution after making contact were measured.

(Comparative Example 1)
110 parts by mass of 0.01 mmol / g calcium chloride aqueous solution is added to 1 part by mass (absolutely dry mass) of phosphorylated pulp (H type) before adsorbing the polyallylamine described in Production Example 1, and the mixture is stirred for 3 minutes. After that, solid-liquid separation was performed by filtration. Under the present circumstances, the electrical conductivity of the calcium chloride aqueous solution before making a pulp and calcium chloride aqueous solution contact, and the electrical conductivity of the calcium chloride aqueous solution after making contact were measured.

(Comparative Example 2)
110 parts by mass of 0.01 mmol / g calcium chloride aqueous solution is added to 1 part by mass (absolute dry mass) of TEMPO oxidized pulp (H type) before adsorbing the polyallylamine described in Production Example 4, and the mixture is stirred for 3 minutes. After that, solid-liquid separation was performed by filtration. Under the present circumstances, the electrical conductivity of the calcium chloride aqueous solution before making a pulp and calcium chloride aqueous solution contact, and the electrical conductivity of the calcium chloride aqueous solution after making contact were measured.

(Comparative Example 3)
110 parts by mass of 0.01 mmol / g calcium chloride aqueous solution is added to 1 part by mass (absolutely dry mass) of the cationized pulp (OH type) before being combined with the phosphorylated cellulose fiber described in Production Example 5. After stirring and mixing for a minute, solid-liquid separation was performed by filtration. Under the present circumstances, the electrical conductivity of the calcium chloride aqueous solution before making a pulp and calcium chloride aqueous solution contact, and the electrical conductivity of the calcium chloride aqueous solution after making contact were measured.

  In the examples, various zwitterionic fibers were obtained. Further, in the examples, the electrical conductivity of the aqueous calcium chloride solution is lowered before and after the contact between the obtained zwitterionic fiber and the aqueous calcium chloride solution, and both the cation and the anion are adsorbed on the both ion fibers. Was suggested.

Claims (5)

  A zwitterionic fiber comprising a first polymer having an ionic functional group and a natural polymer as a base material. The first polymer has an acidic substituent or a basic substituent,
2. The zwitterionic fiber according to claim 1, wherein the zwitterionic fiber includes a second polymer having an acidic substituent or a basic substituent having a charge opposite to that of the charge of the first polymer. The first polymer has an acidic substituent,
The zwitterionic fiber according to claim 2, wherein the second polymer has a basic substituent. The first polymer has a basic substituent,
The zwitterionic fiber according to claim 2, wherein the second polymer has an acidic substituent.   5. The zwitterionic fiber according to claim 1, wherein the first polymer is at least one selected from cellulose, starch, and chitosan.

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