JP5843463B2 - Fibrous material - Google Patents

Description

  The present invention relates to a fibrous material containing cellulose fibers and a conductive polymer and having high conductivity.

  Conventionally, plastic materials derived from petroleum, which is a finite resource, have been widely used, but in recent years, technologies with less environmental impact have come to the spotlight. A material using a certain cellulose fiber has attracted attention, and various improved techniques have been proposed in this regard.

  For example, Patent Document 1 describes a method for producing a conductive fiber composition, which includes a first component having plant fibers such as cellulose fibers and a second component made of a synthetic conductive polymer such as polyaniline. Yes. According to the technique described in Patent Document 1, a complex or salt is formed by reacting a monomer corresponding to a conductive polymer and an organic sulfonic acid as a doping agent for the polymer in an aqueous solution. Alternatively, after a salt is infiltrated into the fiber, a catalyst or an oxidizing agent that enables a polymerization reaction is added to polymerize the monomer in the fiber (in situ polymerization), thereby polymerizing the monomer ( The conductive polymer) adheres firmly to the surface and the interior of the fiber so that in wet papermaking using the fiber, the polymer is not substantially washed away with water before forming the fiber web. It is supposed to be.

  The applicant previously proposed a gas barrier material containing cellulose fibers having an average fiber diameter of 200 nm or less and having a carboxyl group content of 0.1 to 2 mmol / g of cellulose constituting the cellulose fibers ( Patent Document 2). This cellulose fiber is obtained by oxidizing natural cellulose fibers such as wood pulp under a TEMPO catalyst, and then refining the resulting oxide dispersion with a mixer or the like. It is a fine cellulose fiber having a finer fiber diameter than the called fiber. Patent Document 2 does not describe the use of this fine cellulose fiber or its production intermediate (the oxide) as a conductive material or any device for that purpose.

JP 2006-522233 A JP 2009-57552 A

  The fiber composition obtained using the technique described in Patent Document 1 is obtained by attaching a conductive polymer to ordinary wood pulp (mechanical pulp, chemical pulp). At times, it is difficult to say that the inconvenience of the conductive polymer falling off from the wood pulp is sufficiently prevented, and the function as the conductive material may not be stably achieved.

  Accordingly, an object of the present invention is to provide a fibrous material containing cellulose fibers and a conductive polymer, which is less likely to drop off the conductive polymer and is useful as a conductive material.

  As a result of various studies on a novel conductive material using the fine cellulose fiber (cellulose nanofiber) described in Patent Document 2, the present inventors have found that the fine cellulose fiber or an oxide of cellulose fiber that is an intermediate for production thereof. That is, a fibrous material having a structure in which a conductive polymer is attached to cellulose fibers (oxidized cellulose fibers) having a carboxyl group content of cellulose of 0.1 to 3 mmol / g has high conductivity and It was found that the conductive polymer is unlikely to fall off.

  This invention is made | formed based on the said knowledge, and provides the fibrous body containing the cellulose fiber of carboxyl group content 0.1-3 mmol / g, and a conductive polymer, and the molded object containing this fibrous body. This solves the problem.

  The present invention is also a method for producing the fibrous material, wherein (i) a step of obtaining a fiber intermediate by adsorbing an oxidizing agent to the cellulose fiber, and (ii) mixing the fiber intermediate and a monomer. The above-mentioned problem is solved by providing a method for producing a fibrous material, which comprises a step of polymerizing the monomer with the fiber intermediate to obtain the conductive polymer.

  Moreover, this invention is a manufacturing method of the said fibrous material, Comprising: (i) The process which makes an oxidizing agent adsorb | suck to the said cellulose fiber, and obtains a fiber intermediate, (ii) The process of wash | cleaning the said fiber intermediate, and ( iii) Providing a method for producing a fibrous material, comprising the steps of mixing the fiber intermediate and a monomer, and polymerizing the monomer in the fiber intermediate to obtain the conductive polymer. It has been solved.

  The fibrous material of the present invention and a molded body including the fibrous material are less likely to cause the conductive polymer to fall off and are useful as a conductive material. Moreover, the manufacturing method of the fibrous material of this invention can provide the fibrous material of this invention stably.

  The fibrous material of the present invention contains two components, (1) cellulose fiber having a carboxyl group content of 0.1 to 3 mmol / g and (2) a conductive polymer as essential components. In the present invention, it is sufficient that these two components are contained in the fibrous material, and the content is not particularly limited, and an appropriate content is selected as long as the fibrous material can have a predetermined conductivity. be able to. A preferable form of inclusion of these two components in the fibrous material of the present invention is a form in which a conductive polymer is attached to cellulose fibers. Each component will be described in detail below.

  The cellulose fiber according to the present invention has a carboxyl group content (carboxyl group content of cellulose constituting the cellulose fiber) of 0.1 to 3 mmol / g, preferably 0.4 to 1.8 mmol / g, more preferably. 0.6 to 1.5 mmol / g. The fibrous material of the present invention is produced using cellulose fibers having a carboxyl group content in such a range as a raw material, and as a result, is configured to include the cellulose fibers. The carboxyl group content is measured by the following measuring method.

<Measurement method of carboxyl group content>
Take a cellulose fiber with a dry mass of 0.5 g in a 100 ml beaker, add ion-exchanged water to make a total of 55 ml, add 5 ml of 0.01 M sodium chloride aqueous solution to prepare a dispersion, and until the cellulose fibers are sufficiently dispersed The dispersion is stirred. 0.1M hydrochloric acid is added to this dispersion to adjust the pH to 2.5-3, and 0.05M sodium hydroxide aqueous solution is waited for using an automatic titrator (AUT-50, manufactured by Toa DKK Co., Ltd.). The solution is dropped into the dispersion under the condition of 60 seconds, and the conductivity and pH values are measured every minute, and the measurement is continued until the pH is about 11, thereby obtaining an conductivity curve. From this conductivity curve, a sodium hydroxide titration amount is obtained, and the carboxyl group content of the cellulose fiber is calculated by the next command.
Carboxyl group content (mmol / g) = sodium hydroxide titration × sodium hydroxide aqueous solution concentration (0.05 M) / mass of cellulose fiber (0.5 g)

  The cellulose fiber according to the present invention, that is, the cellulose fiber having a carboxyl group content of 0.1 to 3 mmol / g may be a cellulose nanofiber which is a cellulose fiber having a nano-sized fiber diameter. Hereinafter, unless otherwise specified, the term “cellulose fiber according to the present invention” in this specification includes cellulose nanofibers. The average fiber diameter of the cellulose nanofiber according to the present invention is preferably 200 nm or less, more preferably 50 nm or less, and particularly preferably 10 to 1 nm. The average fiber diameter is measured by the following measuring method.

<Measurement method of average fiber diameter>
Water is added to 0.0001% by mass of cellulose fibers at a solid content concentration to prepare a dispersion, and the dispersion is dropped onto mica (mica) and dried, and an atomic force microscope ( NanoNaVi IIe, SPA400, manufactured by SII Nano Technology, Inc., and the probe uses SI-DF40Al manufactured by the same company), and the fiber height of the cellulose fiber in the observed sample is measured. In a microscopic image in which cellulose fibers can be confirmed, five or more cellulose fibers are extracted, and the average fiber diameter is calculated from the fiber heights. In general, the smallest unit of cellulose nanofibers prepared from higher plants is a 36 × 36 molecular chain packed in a substantially square shape. Therefore, the height that can be analyzed by the atomic force microscope image is regarded as the fiber diameter. be able to.

  The carboxyl group content is an important factor in stably obtaining cellulose nanofibers. That is, in the process of biosynthesis of natural cellulose, usually, nanofibers called microfibrils are first formed, and these are bundled to form a higher-order solid structure. Cellulose nanofibers used in the present invention As will be described later, this is obtained by using this in principle, in order to weaken the hydrogen bond between the surfaces, which is the driving force of the strong cohesive force between microfibrils in the naturally-derived cellulose solid raw material. , Part of which is obtained by oxidation and conversion to a carboxyl group. Therefore, the larger the total amount of carboxyl groups present in the cellulose (carboxyl group content), the smaller the fiber diameter, the more stable it can exist, and the electrical repulsive force is generated in water. As a result, the tendency of the microfibrils to break apart without maintaining aggregation is increased, and the dispersion stability of the nanofibers is further increased. When the carboxyl group content is less than 0.1 mmol / g, it is difficult to obtain cellulose nanofibers having a fine fiber diameter of 200 nm or less, and dispersion stability in a polar solvent such as water may be reduced. There is.

  Since the fibrous material of the present invention contains cellulose fibers having a carboxyl group content in the range of 0.1 to 3 mmol / g, the pyrolysis start temperature is a natural cellulose fiber [carboxyl group content. Is lower than the lower limit (0.1 mmol / g) of the above range]. The thermal decomposition start temperature of the fibrous material of the present invention is preferably 150 to 250 ° C, more preferably 180 to 230 ° C. Therefore, whether the cellulose fiber contained in the fibrous material has a carboxyl group content of 0.1 to 3 mmol / g can also be determined by measuring the thermal decomposition start temperature. The pyrolysis start temperature is determined by thermally decomposing the fibrous material under the following thermogravimetric analysis conditions using a thermogravimetric analyzer (eg, TG / DTA6300 manufactured by Seiko Instruments Inc.). It can be measured by measuring the thermal decomposition starting temperature. Thermogravimetric analysis conditions: Thermogravimetric analysis of about 10 mg of fibrous material under nitrogen flow at the following set temperature. The temperature was raised from 30 ° C. to 500 ° C. (rate 40 ° C./min), held at 500 ° C. for 30 minutes, and the temperature was lowered from 500 ° C. to 30 ° C. (rate 40 ° C./min).

  The cellulose fiber according to the present invention has an average aspect ratio (fiber length / fiber diameter) of preferably 10 to 1000, more preferably 10 to 500, and particularly preferably 100 to 350. By using a cellulose fiber having an average aspect ratio in such a range as a material for the fibrous material of the present invention, the molded body containing the fibrous material obtained by the method described later and a moldable polymer material is small. High conductivity is exhibited even with the content of the fibrous material. The average aspect ratio is measured by the following measurement method.

<Measuring method of average aspect ratio>
The average aspect ratio is calculated from the viscosity of a dispersion liquid prepared by adding water to cellulose fibers (mass concentration of cellulose fibers: 0.005 to 0.04 mass%). The viscosity of the dispersion is measured at 20 ° C. using a rheometer (MCR, DG42 (double cylinder), manufactured by PHYSICA). From the relationship between the mass concentration of the cellulose fibers in the dispersion and the specific viscosity of the dispersion with respect to water, the aspect ratio of the cellulose fibers is calculated by the following formula (1) to obtain the average aspect ratio. The following formula (1) is obtained from The Theory of Polymer Dynamics, M .; DOI and D.D. F. EDWARDS, CLARENDON PRESS · OXFORD, 1986 , P312 viscosity rigid-rod molecules according to equation (8.138), the relationship wherein the ^{Lb 2 × ρ = M / N} A, L is the fiber length, b is fiber width (The cross section of the cellulose fiber is a square), ρ is the concentration of the cellulose fiber (kg / m ³ ), M is the molecular weight, and N _A is the Avogadro number. In the viscosity formula (8.138), rigid rod-like molecules = cellulose fibers. In the following formula (1), η _SP is the specific viscosity, π is the circumference ratio, ln is the natural logarithm, P is the aspect ratio (L / b), γ = 0.8, ρ _S is the density of the dispersion medium ( kg / m ³ ), ρ ₀ represents the density of cellulose crystals (kg / m ³ ), and C represents the mass concentration of cellulose (C = ρ / ρ _S ).

  The cellulose fiber (cellulose fiber having a carboxyl group content of 0.1 to 3 mmol / g) according to the present invention can be produced by oxidizing natural cellulose fiber, and is an oxidized cellulose fiber. Specifically, first, a slurry in which natural cellulose fibers are dispersed in water is prepared. The slurry is obtained by adding about 10 to 1000 times (mass basis) of water to the natural cellulose fiber (absolute dry basis) as a raw material, and processing with a mixer or the like. Examples of natural cellulose fibers include wood pulp such as softwood pulp and hardwood pulp; cotton pulp such as cotton linter and cotton lint; non-wood pulp such as straw pulp and bagasse pulp; bacterial cellulose and the like. These 1 type can be used individually or in combination of 2 or more types. The natural cellulose fiber may be subjected to a treatment for increasing the surface area such as beating.

  Next, natural cellulose fibers are oxidized in water using an N-oxyl compound as an oxidation catalyst. Examples of N-oxyl compounds that can be used as an oxidation catalyst for cellulose include TEMPO, 4-acetamido-TEMPO, 4-carboxy-TEMPO, 4-phosphonooxy-TEMPO, and the like. A catalytic amount is sufficient for the addition of these N-oxyl compounds, and is usually in a range of 0.1 to 10% by mass with respect to natural cellulose fibers (absolute dry basis) used as a raw material.

  In the oxidation treatment of the natural cellulose fiber, cooxidation with an oxidizing agent (for example, hypohalous acid or a salt thereof, hypohalous acid or a salt thereof, perhalogenic acid or a salt thereof, hydrogen peroxide, a perorganic acid, etc.) An agent (for example, an alkali metal bromide such as sodium bromide) is used in combination. As the oxidizing agent, alkali metal hypohalites such as sodium hypochlorite and sodium hypobromite are particularly preferable. The amount of the oxidizing agent used is usually in the range of about 1 to 100% by mass with respect to the natural cellulose fiber (absolute dry standard) used as a raw material. Moreover, the usage-amount of a co-oxidant is the range used as about 1-30 mass% normally with respect to the natural cellulose fiber (absolute dry reference | standard) used as a raw material.

  Moreover, in the oxidation treatment of the natural cellulose fiber, the pH of the reaction solution (the slurry) is preferably maintained in the range of 9 to 12 from the viewpoint of allowing the oxidation reaction to proceed efficiently. The temperature of the oxidation treatment (the temperature of the slurry) is arbitrary at 1 to 50 ° C., but the reaction is possible at room temperature, and no temperature control is required. The reaction time is preferably 1 to 240 minutes.

  After the oxidation treatment of the natural cellulose fiber, a purification treatment is performed to remove impurities other than the oxidized cellulose fiber and water contained in the slurry, such as unreacted oxidant and various by-products. This purification treatment can be carried out, for example, by a purification method that repeats washing with water and filtration, and the purification device used in that case is not particularly limited. In this way, the target oxidized cellulose fiber (cellulose fiber having a carboxyl group content of 0.1 to 3 mmol / g) is obtained. The form of the oxidized cellulose fiber is not particularly limited, and can be, for example, a dried fiber or powder. In the oxidized cellulose fiber, the hydroxyl group at the C6 position of the cellulose constituent unit in the natural cellulose fiber is selectively oxidized to a carboxyl group through an aldehyde group by the oxidation treatment, and natural cellulose which is a starting material for the oxidation treatment Compared to the fiber, the carboxyl group content is increased.

  In the present invention, as the cellulose fiber, an oxidized cellulose fiber obtained by oxidation treatment of such natural cellulose fiber can be used as it is, but as described above, it has a nano-sized fiber diameter (the average fiber diameter is Cellulose nanofibers (preferably 200 nm or less) can also be used. The cellulose nanofiber can be produced by the following method using the oxidized cellulose fiber as a raw material, and is a kind of oxidized cellulose fiber. That is, the cellulose nanofibers used in the present invention can be obtained by a production method including an oxidation reaction step of oxidizing natural cellulose fibers to obtain oxidized cellulose fibers, and a refining step of refining the oxidized cellulose fibers. The oxidation reaction step is the same as the oxidation treatment, and usually includes the purification treatment.

  In the refinement step, the oxidized cellulose fiber obtained by the oxidation treatment and the purification treatment of the natural cellulose fiber is dispersed in a solvent such as water and subjected to the refinement treatment. Oxidized cellulose fibers are made into cellulose nanofibers having an average fiber diameter and an average aspect ratio in the above-mentioned range by passing through such a refinement step.

  In the above-mentioned micronization treatment, the solvent as the dispersion medium is usually preferably water, but water-soluble organic solvents (alcohols, ethers, ketones, etc.) may be used in addition to water depending on the purpose. These mixtures can also be suitably used. Examples of the disperser used in the miniaturization process include a disaggregator, a beater, a low pressure homogenizer, a high pressure homogenizer, a grinder, a cutter mill, a ball mill, a jet mill, a short shaft extruder, a twin screw extruder, and an ultrasonic stirrer. A home juicer mixer or the like can be used. The solid content concentration of the oxidized cellulose fiber in the refining treatment is preferably 50% by mass or less. When the solid content concentration exceeds 50% by mass, it is not preferable because extremely high energy is required for dispersion.

  As the form of the cellulose nanofibers obtained after the above-mentioned micronization step, it is a suspension in which the solid content concentration is adjusted, or a powder that has been subjected to a drying treatment (however, a powder in which cellulose fibers are aggregated, and cellulose particles Does not mean that). In the case of a suspension, only water may be used as a dispersion medium, and a mixed solvent of water and other organic solvents (for example, alcohols such as ethanol), surfactants, acids, bases, etc. May be used.

  By such oxidation treatment and refinement treatment of natural cellulose fiber, the hydroxyl group at the C6 position of the cellulose constituent unit is selectively oxidized to a carboxyl group via an aldehyde group, and the carboxyl group content is 0.1 to 0.1. Highly crystalline cellulose fibers (cellulose nanofibers) made of 3 mmol / g cellulose and having an average fiber diameter of preferably 200 nm or less can be obtained. This highly crystalline cellulose fiber has a cellulose I-type crystal structure. This means that the cellulose nanofiber used in the present invention is a fiber obtained by surface-oxidizing and refining a naturally-derived cellulose solid raw material having an I-type crystal structure. In other words, natural cellulose fibers have a high-order solid structure in which fine fibers called microfibrils produced in the process of biosynthesis are bundled to form a high-order solid structure. The cellulose nanofibers can be obtained by weakening the hydrogen bond) by introducing the aldehyde group or carboxyl group by the oxidation treatment, and further through the refinement treatment. Then, by adjusting the conditions of the oxidation treatment, the carboxyl group content is increased or decreased within a predetermined range, the polarity is changed, or the electrostatic repulsion of the carboxyl group or the refinement treatment is performed on the cellulose fiber. The average fiber diameter, average fiber length, average aspect ratio, etc. can be controlled.

  The fibrous material of the present invention contains a conductive polymer in addition to cellulose fibers (oxidized cellulose fibers) having a carboxyl group content of 0.1 to 3 mmol / g. In the fibrous material of the present invention, the conductive polymer is preferably attached to the oxidized cellulose fiber, and the conductive polymer and the oxidized cellulose fiber are integrated. According to the method for producing a fibrous material of the present invention described later, a fibrous material having a conductive polymer uniformly attached to the surface of oxidized cellulose fiber (cellulose nanofiber) can be stably obtained.

  As the conductive polymer according to the present invention, a known polymer material having conductivity can be used without particular limitation, and examples thereof include polypyrrole, polyaniline, polyacetylene, polythiophene, and the like. Or in combination of two or more. Among these, in particular, at least one selected from the group consisting of polypyrrole and polyaniline is preferable from the viewpoint of adhesion to cellulose fibers.

The content of the conductive polymer in the fibrous material of the present invention is preferably 10 to 90% by mass, more preferably 30 to 80% by mass. The fibrous material of the present invention has a surface resistivity of 10 ⁴ to 10 ⁸ Ω / □ (or Ω / sq., Hereinafter referred to as Ω / sq.), Particularly from the viewpoint of exhibiting practically sufficient conductivity (antistatic property). In particular, it is preferably at a level of less than 10 ⁵ Ω / □. If the surface resistivity is the same value, the content of the conductive polymer is preferably low, and the content of the conductive polymer is preferably in the above range from the viewpoint of setting the surface resistivity in the above range. The content of the conductive polymer can be calculated by using a change in weight before and after the production of the fibrous material described later and a difference in thermal decomposition temperature by thermogravimetric analysis. The surface resistivity of the fibrous material is measured by a method described later, and is equal to the surface resistivity of the molded article of the present invention including the fibrous material.

The fibrous material of the present invention preferably contains an iron ion in addition to the oxidized cellulose fiber and the conductive polymer described above, and the iron ion is added to the carboxyl group of the oxidized cellulose fiber in the fibrous material of the present invention. Adsorbed. More specifically, in the method for producing a fibrous product of the present invention, which will be described later, a step of polymerizing a monomer on oxidized cellulose (on the surface and / or inside of oxidized cellulose) to obtain a conductive polymer and Prior to this step, a step of obtaining a fiber intermediate by adsorbing an oxidizing agent to the oxidized cellulose fiber is performed, and iron ion (ferric ion: Fe ³⁺ ) is preferably used as this oxidizing agent. In the fibrous material obtained by such a production method, ferric ions are adsorbed on the carboxyl group at the C6 position of the cellulose constituent unit of the oxidized cellulose fiber in the step of obtaining the fiber intermediate, so that the C6 position is COO. ^- it has become a Fe ^3+. The amount of iron ions adsorbed is measured by elemental analysis such as fluorescent X-ray analysis or inductively coupled plasma emission spectroscopy (ICP-AES).

  The fibrous material of the present invention can be produced, for example, as follows. The production method of this embodiment comprises (i) a step of obtaining a fiber intermediate by adsorbing an oxidizing agent to cellulose fibers (oxidized cellulose fibers) having a carboxyl group content of 0.1 to 3 mmol / g, and (ii) the fibers A step of mixing an intermediate and a monomer and polymerizing the monomer in the fiber intermediate to obtain a conductive polymer;

In the step (i) of the present embodiment, first, a slurry in which oxidized cellulose fibers (or cellulose nanofibers) are dispersed in water is prepared. The slurry is obtained by adding about 10 to 1000 times (mass basis) of water to the oxidized cellulose fiber (absolute dry basis) as a raw material and stirring. Next, an oxidizing agent is added to the slurry and mixed and stirred. As the oxidizing agent, for example, oxidizing agents such as ferric ion (Fe ³⁺ ), dichromate ion, iodic acid, persulfate ion can be used. Therefore, compounds that form these ions in water can be used. Can be used. For example, ferric chloride (FeCl ₃ ) that forms trivalent iron ions (ferric ions) in water is preferably used in the present invention as an oxidizing agent. When ferric chloride as an oxidizing agent is added to the slurry (aqueous dispersion) of oxidized cellulose fibers, ferric chloride-derived ferric ions (Fe ³⁺ ) are in the C6 position of the cellulose constituent unit of the oxidized cellulose fibers. It is ion-exchanged with sodium ion (Na ⁺ ) in the carboxyl group (COONa) of ^{CO 2} and adsorbed as COO ⁻ Fe ^{3+ at the} C6 position. Thus, a fiber intermediate is obtained in which the oxidizing agent is adsorbed on the oxidized cellulose fiber.

  In the step (i) of the present embodiment, the addition amount of the oxidizing agent is preferably 10 to 2000 parts by mass, more preferably 50 to 1000 parts by mass with respect to 100 parts by mass of the oxidized cellulose fiber.

  Subsequently, in the step (ii) of this embodiment, a monomer corresponding to the conductive polymer (for example, pyrrole if the conductive polymer is polypyrrole) and a dopant are added to the slurry of the fiber intermediate, Mix and stir with a stirrer at room temperature. The order of adding the monomer and the dopant to the slurry is not particularly limited, and these may be added simultaneously. By adding monomer and dopant to the slurry, the polymerization reaction of the monomer is initiated. The polymerization reaction time is usually about 0.5 to 24 hours, although it depends on the type of monomer. It is preferable to stir the slurry during the polymerization reaction.

  The dopant acts as a charge carrier for a conductive polymer with a conjugated structure in which double bonds and single bonds are arranged alternately, such as polypyrrole, to give high conductivity to the fibrous material. It is used to do. As a dopant, when pyrrole is used as a monomer, an organic sulfonic acid such as 2-naphthalenesulfonic acid, dodecylbenzenesulfonic acid, benzenesulfonic acid and the like can be used.

  In the step (ii) of this embodiment, it is preferable to adjust the amount of the monomer added so that the content of the conductive polymer in the finally obtained fibrous material is within the above range. Moreover, the addition amount of the dopant is preferably 10 to 200 parts by mass, and more preferably 50 to 100 parts by mass with respect to 100 parts by mass of the monomer.

  In the step (ii), the monomer corresponding to the conductive polymer uses the fiber intermediate obtained in the step (i) (oxidized cellulose fiber adsorbed with an oxidizing agent) as a reaction field, so-called insight. Polymerization (in-situ polymerization) results in a conductive polymer attached to the fiber intermediate. For example, when ferric ion (ferric chloride) is used as the oxidizing agent, pyrrole is used as the monomer, and 2-naphthalenesulfonic acid is used as the doping agent, in the step (ii), the cellulose constituent unit of the fiber intermediate is used. A pyrrole polymerization reaction takes place on the surface and / or inside of the fiber intermediate using the carboxyl group adsorbed with ferric ions at the C6 position as a conductive polymer, and as a result, a conductive polymer attached to the fiber intermediate. Of polypyrrole is produced. The polypyrrole thus produced is uniformly attached to the surface of the fiber intermediate, and a thin film of polypyrrole is formed on the surface.

  After the completion of the polymerization reaction, the precipitate in the slurry is washed with a sufficient amount of ion-exchanged water to obtain the target fibrous material. The form of the fibrous material is not particularly limited, and can be, for example, a dried fibrous or powdery form.

  The fibrous material can also be used in the form of a dispersion in which the washed fibrous material is dispersed in water. At that time, since many of the conductive polymers are hydrophobic, they may be appropriately dispersed using a surfactant or the like. For example, the fibrous material after washing is 0.2% by mass with ion-exchanged water, sodium dodecyl sulfate and polyvinyl pyrrolidone are added, and then treated with an ultrasonic disperser or the like, whereby a highly dispersible fibrous material. A dispersion is obtained.

  The manufacturing method of the fibrous material of this invention is not restrict | limited to the said embodiment. For example, in the embodiment, after the step (i) and before the step (ii), the fiber intermediate obtained in the step (i) (the oxidant is added to the carboxyl group at the C6 position of the cellulose constituent unit). You may implement the process of wash | cleaning the oxidized cellulose fiber which adsorb | sucked. More specifically, the oxidized cellulose fiber adsorbed with the oxidizing agent and the oxidizing agent by the solid-liquid separation method such as filtration or centrifugation of the fiber intermediate slurry (aqueous dispersion) obtained in the step (i). Separated and washed with water. After washing the oxidized cellulose fiber adsorbed with the oxidizing agent, it is dispersed again in water, and then the conductive polymer is polymerized in the step (ii). By carrying out this washing step, only the oxidant adsorbed on the fiber surface or inside is present, and no oxidant is present in the reaction solvent water. Therefore, the polymerization of the conductive polymer is performed on the fiber surface. Or it progresses only inside. By carrying out such a fiber intermediate washing step, the obtained fibrous material has an effect that the conductive polymer is less likely to fall off. At the same time, since the composition of only the conductive polymer polymerized in the solvent (that is, the conductive polymer not attached to the cellulose fiber) is small, the production efficiency of the fibrous material with respect to the added amount of monomer is high, and the wastewater after the reaction This is accompanied by the effect that the contamination of the water can be reduced.

  The fibrous material of the present invention obtained as described above is a cellulose fiber (cellulose nanofiber) that functions as a base material to which a conductive polymer adheres, and has a carboxyl group content of 0.1 to 3 mmol / g. Oxidized cellulose fiber), the conductive polymer uniformly adheres to the surface of the cellulose fiber. Therefore, as in the fiber composition described in Patent Document 1, natural cellulose fiber (carboxyl group content is 0.1 mmol / g). Less than cellulose fibers) and a conductive polymer containing a conductive polymer, the dropout rate of the conductive polymer is low. More specifically, in the fibrous material of the present invention, the dropout rate of the conductive polymer measured by the following method is preferably 50% or less, more preferably 30% or less, and the dropout of the conductive polymer occurs. hard.

<Measuring method of dropout rate of conductive polymer>
The fiber (fibrous object) to be measured is subjected to a dropping treatment of the conductive polymer, and the dropping rate (%) is calculated from the weight of the fiber before and after the dropping process by the following formula. The drop-off process is performed as follows. About 0.05 g of fiber (fibrous material) is added to 800 times the amount of water of the fiber to obtain a slurry, and the slurry is mixed using a mixer (manufactured by Nippon Seiki Seisakusho, trade name: EXCEL HOMOGENIZER). After stirring for 1 minute at 5000 rpm, the fiber is filtered through a glass filter (pore size 16 μm) and subsequently filtered through 100 g of ion-exchanged water. After the fibers are dried, the weight of the fibers (dry weight of the fibers after the dropping process) is measured.
Dropping rate of conductive polymer (%) = {(dry weight of fiber before dropping process−dry weight of fiber after dropping process) / dry weight of fiber before dropping process} × 100

  In addition, as described above, the content of the conductive polymer in the fibrous material of the present invention is the weight change before and after the production of the fibrous material, the Fourier transform infrared spectroscopy (FT-IR), the heat by thermogravimetric analysis. It can be calculated using the difference in decomposition temperature. Specifically, for example, the content of the conductive polymer can be calculated from the change in the weight of the solid content before and after the production of the fibrous material as follows. . That is, the solid content weight of the oxidized cellulose fiber used in the step (i) is A (g), and the solid content weight of the fibrous material obtained by washing with ion-exchanged water after the step (ii) is In the case of B (g), the conductive polymer content C (%) is calculated by the following equation. C = {(B−A) / B} × 100

By the way, when the conductive polymer is unevenly distributed on a part of the cellulose fiber surface, the non-conductive cellulose is exposed, so the conductivity per content of the conductive polymer is lowered. Due to the fact that the conductive polymer is uniformly adhered to the surface of the cellulose fiber, the conductivity per conductive polymer content is high, and therefore the surface resistivity per conductive polymer content is high. Low. More specifically, the fibrous material of the present invention has a surface resistivity per conductive polymer content of preferably 10 ⁸ Ω / □ or less, more preferably 10 ⁴ to 10 ⁶ Ω / □.

  The surface resistivity of the fibrous material and the surface resistivity per conductive polymer content are measured and calculated as follows. Regarding the surface resistivity of the fibrous material, the fibrous material to be measured is molded into an arbitrary shape by a method described later (melt kneading method, casting method, wet papermaking method, impregnation method, etc.) to obtain a molded body. Using a resistance meter (measured by ADVANTEST, R8340A, 200V), the surface resistivity D (Ω / □) of the molded body is measured, and the measured value is defined as the surface resistivity of the fibrous material. Further, the surface resistivity per conductive polymer content is calculated by the following equation using the conductive polymer content C (%) in the fibrous material to be measured (the molded article). Surface resistivity per conductive polymer content = D × C / 100

  The fibrous material of the present invention is less likely to cause the conductive polymer to fall off, and is useful as a conductive material. For example, it is suitable for an electromagnetic shielding material, an antistatic agent, a battery electrode material, a touch panel electrode film, and the like. In addition, the fibrous material of the present invention has a structure in which a conductive polymer is attached to the surface of cellulose fiber, so that it is compared with a conductive material using a conductive polymer such as polypyrrole alone (without using fibers). Thus, it is easy to form and form a sheet, and is excellent in moldability. Also, since the cellulose fiber functions as an aggregate, it is excellent in strength. In particular, when cellulose nanofibers are used as the cellulose fibers, when the fibrous material of the present invention thus obtained is mixed with a transparent resin, while maintaining the transparency of the resin, It is possible to impart practically sufficient conductivity (antistatic property) to the resin.

  Next, the molded product of the present invention will be described. The molded body of the present invention includes the above-described fibrous material of the present invention, and may be composed only of the fibrous material, or in addition to the fibrous material, a moldable polymer. You may be comprised including material.

  When the molded body of the present invention is composed only of the above-described fibrous material of the present invention (when it does not contain a moldable polymer material), the molded body is obtained by a known casting method or wet papermaking method. It can be formed into a thin product such as a film or sheet. When the casting method is used, for example, a fluid obtained by dispersing or dissolving a fibrous material in a solvent is cast-coated on a substrate, the solvent is removed to obtain a film, and the film is subjected to hot press As a result, a desired thin-film (film-like) shaped body is obtained. In the wet papermaking method, first, a fibrous slurry (aqueous dispersion) is prepared, and according to a conventional method, the slurry is poured onto a wet papermaking machine to make it thin and flat. A shaped molded body (wet web) is formed, and the wet web is subjected to a dehydration treatment as necessary, followed by a drying treatment, whereby a desired thin film (sheet-like) shaped body is obtained. The casting method is particularly suitable when the oxidized cellulose fiber constituting the fibrous material of the present invention is a cellulose nanofiber, and the wet papermaking method is particularly preferable when the oxidized cellulose fiber is not a cellulose nanofiber. .

  In the molded body of the present invention, the “moldable polymer material” used in combination with the fiber material of the present invention is obtained by subjecting the polymer material alone or a mixture of the polymer material and other materials to the necessary processing. In addition, it means a polymer material in a case where an object having a predetermined shape can hold the predetermined shape for a certain period of time. For example, a resin derived from a fossil resource that can be used for ordinary plastic molding is included in the “moldable polymer material”. The moldable polymer material can be made into an object having a predetermined shape through necessary processing (processing for making the polymer material different from its original form). Specifically, Those having thermoplasticity, those having thermosetting properties, those soluble in an organic solvent, those dispersed in an organic solvent, those soluble in water, those dispersed in water, and the like can be mentioned. By using a moldable polymer material, the molded article of the present invention can be molded into thin objects such as films and sheets, three-dimensional containers such as boxes and bottles, housings for information appliances, bodies of automobiles, etc. Can do.

  Examples of moldable polymer materials used in the present invention (hereinafter also simply referred to as polymer materials) include a) biomass-derived polymers and b) synthetic polymers. Biomass-derived polymers are organic polymers obtained from living organisms, excluding fossil resources, and include those having biodegradability similar to cellulose fibers (oxidized cellulose fibers) according to the present invention. Preferred examples of the biomass-derived polymer include thermoplastics such as polylactic acid (PLA), polyglycolic acid, poly (3-hydroxybutanoic acid), biopolyethylene, biopolypropylene, biopolyethylene terephthalate, and biopolycarbonate. Can be mentioned.

  In addition to the PLA and the like, polysaccharides can also be used as the biomass-derived polymer. Examples of the polysaccharide include pulp, such as wood pulp such as softwood pulp and hardwood pulp; non-wood pulp such as hemp, bamboo, straw and kenaf; cotton pulp such as cotton linter and cotton lint. It is done. Examples of polysaccharides other than pulp that can be used in the present invention include, for example, regenerated cellulose such as rayon, polysaccharides such as starch, chitin, chitosan, cellulose triacetate (TAC), and carboxymethylcellulose (CMC), and polysaccharide derivatives. Etc. These polysaccharides are all non-thermoplastic.

  The synthetic polymer (moldable polymer material) used in the present invention is an organic polymer obtained from a fossil resource. For example, polyolefin resin, polystyrene resin, nylon resin, methacrylic resin, polyvinyl alcohol (PVA). And thermoplastic resins such as acrylonitrile, butadiene, and styrene resins; and thermosetting resins such as epoxy resins, phenol resins, urea resins, and polyimide resins. These resins can be used singly or in combination of two or more.

  The content of the moldable polymer material in the molded body of the present invention is preferably 40 to 99.99 mass relative to the total mass of the molded body from the viewpoint of imparting high mechanical strength and conductivity to the molded body. %, More preferably 80 to 99% by mass.

  When the molded product of the present invention is configured to include both the above-described fibrous material of the present invention and a moldable polymer material, the configuration is as follows: 1) A layer mainly composed of a fibrous material (fibrous material) A multilayer structure in which a layer having a content of 1% by mass or more) and a layer mainly composed of a polymer material (a layer having a polymer material content of 99% by mass or more) are laminated, or 2) A structure in which the fibrous material and the polymer material are dispersed substantially uniformly throughout the molded body (both components are not substantially unevenly distributed, mainly a layer mainly composed of a fiber material or a polymer material) It may be a structure that does not have a layer to perform.

  The molded body of the present invention may contain other components other than the above-described two components (fibrous materials, polymer materials) as necessary, for example, inorganic materials such as clay minerals, inorganic materials, and metal materials represented by glass and concrete. It may contain material.

  The molded body of the present invention can be molded into an arbitrary shape, and is provided as a thin object such as a film or a sheet, a block shape such as a rectangular parallelepiped or a cube, or other three-dimensional shapes.

  When the molded body of the present invention is configured to include both components of a fibrous material and a moldable polymer material, for example, the molded body can be obtained by mixing a fibrous material and a polymer material to form a uniform mixture. After being obtained, it can be produced by molding the uniform mixture into an arbitrary shape.

  As the form of the fibrous material used as the raw material of the molded product of the present invention, in consideration of the polymer material used together with the fibrous material, the apparatus used for kneading, etc. And does not mean a spherical particulate material), a suspension, or the like.

  Examples of the fibrous fibrous material include a dried product obtained by directly drying an aqueous dispersion of the fibrous product; a powder obtained by pulverizing the dried product by mechanical processing; an undried product of the aggregate; and a fibrous product. And an aqueous dispersion obtained by pulverizing an aqueous dispersion of a fibrous material by a known freeze-drying method. The spray drying method is a method in which an aqueous dispersion of a fibrous material is sprayed in the air and dried.

  Further, as the suspension-like fibrous substance, an aqueous dispersion of the fibrous substance can be used as it is, or a powder-like fibrous substance dispersed in an arbitrary medium is used. You can also. The medium can be appropriately selected depending on the polymer material to be mixed and the mixing and molding methods described later. For example, when polyvinyl alcohol (PVA) is used as the polymer material and a molded body is produced by a casting method described later, water or alcohol can be used as the medium.

  When the polymer material used in combination with the fibrous material in the present invention is a thermoplastic polymer derived from biomass (for example, polylactic acid) or a synthetic polymer, for example, it is heated and melted. A method of adding a fibrous material to a polymer material, kneading these while the polymer material is maintained in a molten state, and forming a uniform mixture thus obtained (hereinafter also referred to as a melt kneading method) ), The molded article of the present invention can be produced. In that case, as a kneading apparatus, for example, a known apparatus such as a single-shaft kneading extruder, a twin-screw kneading extruder, or a pressure kneader can be used. For example, when a thermoplastic resin such as polylactic acid is used as the polymer material, the powdery fibrous material is added to the molten thermoplastic resin, and then the powdery material is obtained using a biaxial kneader. The fibrous material is uniformly dispersed in the thermoplastic resin to obtain resin pellets, and the resin pellets are heated and compressed to obtain a sheet-like molded body. Alternatively, by using a known plastic molding method, specifically injection molding, casting, extrusion molding, blow molding, stretch molding, foam molding, etc., a molded body having a block shape or other three-dimensional shape can be obtained. it can.

  Moreover, the casting method is mentioned as a manufacturing method of molded objects other than the melt kneading method. The casting method is a method in which a mixed fluid in which a fibrous material and a polymer material are dispersed or dissolved in a solvent is cast-coated on a substrate, the solvent is removed to obtain a film, and the film is subjected to hot pressing. Thus, this is a method for obtaining a thin-film shaped product. For example, a powdered fibrous material is added to a polymer material dissolved in an organic solvent to obtain a mixed fluid, and a molded film or sheet is obtained from the mixed fluid by a casting method. Can do. The casting method can be widely applied to all the biomass-derived polymers and synthetic polymers described above, regardless of the type of polymer material.

  In the casting method, as a method for removing the solvent from the mixed fluid applied on the base material, for example, a liquid-permeable base material (for example, a porous material having a large number of liquid-permeable holes penetrating in the thickness direction). A method using a conductive substrate). In this method, by applying the mixed fluid onto the liquid-permeable substrate, the solvent in the mixed fluid is removed by permeating through the porous substrate, and the solid content (fibrous material and polymer material) is removed. Is scraped onto the porous substrate. Another solvent removal method includes a method in which the mixed fluid is cast-coated on a substrate and then the mixed fluid is dried by a drying method such as natural drying or hot air drying. Moreover, in the casting method, the hot pressing performed on the film obtained after removing the solvent can be performed using a known apparatus such as a pressing type or a rotary type using a metal plate, for example.

  Moreover, the molded object of this invention can also be manufactured by the wet papermaking method. The wet papermaking method is particularly effective when the polymer material used in combination with the fibrous material in the present invention is a polysaccharide (for example, non-thermoplastic material such as pulp) which is a kind of polymer derived from biomass. . In the wet papermaking method, first, a slurry in which a fibrous material and a polymer material (polysaccharide) are uniformly mixed is obtained, and according to a conventional method, the slurry is flowed on a net of a wet papermaking machine to make it thin and flat. A wet sheet-like molded body (wet web) is formed. The wet web is subjected to a dehydration treatment as necessary, followed by a drying treatment, whereby a sheet-like molded body is obtained.

  In the wet papermaking method, the dewatering / drying treatment of the wet web can be performed using, for example, a press part and a dryer part in a papermaking process in a normal wet papermaking method. Specifically, first, in the press part, the wet web is pressed with a felt (blanket) as necessary and compressed from above and below to squeeze out the water in the web, and then in the dryer part, a drying means is used. Then, the wet fiber web that has been dehydrated is dried. Thus, a sheet-like molded body is obtained. There is no particular limitation on the drying means, and a Yankee dryer or an air-through dryer can be used. As the wet paper machine, for example, a long paper machine, a twin wire paper machine, an on-top paper machine, a hybrid paper machine, a round paper machine and the like can be used. The wet papermaking method can be used not only for the production of a sheet-like molded product but also for the production of a desired three-dimensional shaped product.

  Moreover, the molded object of this invention can also be manufactured by the impregnation method. That is, the molded article of the present invention may be obtained by impregnating a fiber assembly mainly composed of the above-described fibrous material of the present invention with a liquid containing a polymer material. This fiber assembly is a sheet-like or desired three-dimensional fiber assembly that does not substantially contain a polymer material (excluding the conductive polymer constituting the fibrous material). Or a pulp mold forming method. In the method for producing a molded body using the impregnation method, the fiber assembly is immersed in a liquid containing a polymer material, and the liquid is infiltrated into the fiber assembly. The liquid containing the polymer material is obtained by dispersing or dissolving the polymer material in an appropriate solvent such as water. After the fiber assembly is immersed in a liquid containing a polymer material, the fiber assembly is dried by a drying method such as natural drying or hot air drying to obtain a molded body having a desired shape.

  Moreover, according to this invention, it is possible to provide a molded object with high transparency. In particular, when polyvinyl alcohol is used as the polymer material, high conductivity and mechanical strength can be expressed with a relatively small amount of fibrous material (content of 5% by mass or less). A molded article having practically sufficient conductivity and mechanical strength can be obtained without impairing the high transparency.

  EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples, but the present invention is not limited to such examples.

[Method for producing oxidized cellulose fiber]
Soft cellulose bleached kraft pulp (Fletcher Challenge Canada, CSF 650 ml) is used as the raw natural cellulose fiber, TEMPO (ALDRICH, Free radical, 98%) is used as the oxidation catalyst, and sodium hypochlorite (Japanese sum) Kobunyaku Kogyo Co., Ltd., Cl: 5%) was used, and sodium bromide (manufactured by Wako Pure Chemical Industries, Ltd.) was used as a co-oxidant. 9900 g of ion-exchanged water is added to 100 g of natural cellulose fibers and sufficiently stirred to obtain a slurry. In the slurry, TEMPO is 1.25% by mass of pulp, sodium bromide is 12.5% by mass of pulp, hypochlorite. 28.4% by mass of sodium acid to pulp was added in this order, and the pH of the slurry was maintained at 10.5 by adding 0.5 M sodium hydroxide dropwise using a pH stud, and the temperature was 20 to 0. The natural cellulose fiber was oxidized at 0 ° C. The dropping of sodium hydroxide was stopped after an oxidation time of 120 minutes, and the natural cellulose fiber after the oxidation treatment was sufficiently washed with ion-exchanged water and dehydrated. Thus, an oxidized cellulose fiber having a carboxyl group content of 1.2 mmol / g was obtained.

[Method for producing cellulose nanofiber]
Oxidized cellulose fiber 10 g (converted to solid content) obtained in [Oxidized cellulose fiber production method] and 990 g of ion-exchanged water were mixed for 120 minutes with a mixer (Vita-mix-Blender ABSOLUTE, manufactured by Osaka Chemikel Co., Ltd.). Stirring was performed (that is, the fine processing time was 120 minutes). Thus, a suspension of cellulose nanofibers having an average fiber diameter of 4 nm and a carboxyl group content of 1.2 mmol / g (solid content concentration of 1.0% by mass) was obtained.

[Example 1]
Using the cellulose nanofibers obtained in the above [Method for producing cellulose nanofiber], using ferric chloride as the oxidizing agent, using pyrrole as the monomer corresponding to the conductive polymer, and using 2-naphthalenesulfonic acid as the doping agent The fibrous material was produced by a method according to the method for producing the fibrous material of the present invention described above. More specifically, after adding 10 g of ferric chloride dissolved in 100 g of ion-exchanged water to 500 g of cellulose nanofiber dispersion diluted to 0.2% by mass with ion-exchanged water and stirring for 30 minutes, 10.9 g of pyrrole dispersed in 100 g of ion-exchanged water and 10.9 g of 2-naphthalenesulfonic acid dissolved in 100 g of ion-exchanged water were added and stirred at room temperature for 12 hours. After completion of the reaction, 50 g of the dispersion containing the fibrous material was placed in a conical tube and centrifuged at 10,000 rpm for 10 minutes using a centrifuge (Universal Cooling Centrifuge 5922, manufactured by Kubota Corporation). After adding 40 g of ion-exchanged water to the conical tube after centrifugation and washing again by centrifugation, the fibrous material was recovered. The content of the conductive polymer was calculated from the weight of the fibrous material thus obtained. Furthermore, the molded object was manufactured only from the obtained fibrous material by the casting method. More specifically, 0.2 g of fibrous material was added to 40 g of ion-exchanged water and stirred. In another container, 0.2 g of sodium dodecyl sulfate and 0.3 g of polyvinylpyrrolidone were dissolved in 100 g of water. After 0.2 g of this solution was added to the dispersion of the fibrous material, the dispersion was treated with an ultrasonic homogenizer for 30 seconds, and then the dispersion was poured into a polystyrene petri dish (φ90 mm). Let stand for a week and dry. The thin film-like molded body thus obtained was used as a sample of Example 1.

[Example 2]
A fibrous material was produced in the same manner as in Example 1 except that the polymerization reaction time was changed to 4 hours, and a thin film-like molded product was produced by a casting method using the fibrous material. It was.

Example 3
A fibrous material was produced in the same manner as in Example 1 except that the polymerization reaction time was set to 1 hour, and a thin film-like molded product was produced by a casting method using the fibrous material. It was.

Example 4
A fibrous material was produced in the same manner as in Example 1 except that the step of washing the fiber intermediate was performed. Specifically, in the same manner as in Example 1, ferric chloride was added to the cellulose nanofiber dispersion and stirred for 30 minutes, and then 50 g of the dispersion was put into a conical tube and centrifuged (universal cooling centrifuge 5922). The product was centrifuged at 10,000 rpm for 10 minutes to remove the oxidizing agent contained in the solvent. 500 g of ion-exchanged water was added to the recovered fiber intermediate. Thereafter, an oxidizing agent and a dopant were added in the same manner as in Example 1 to obtain a fibrous material. Then, in the same manner as in Example 1, a thin film-like molded body was produced by the casting method using the obtained fibrous material, and this was used as a sample of Example 4.

Example 5
A fibrous material was produced in the same manner as in Example 1 except that the oxidized cellulose fiber obtained in the above [Method for producing oxidized cellulose fiber] was used instead of the cellulose nanofiber. Using the obtained fibrous material, a thin-film shaped product was produced by a wet papermaking method, and this was used as a sample of Example 5. More specifically, in the production of a molded article by the wet papermaking method of Example 5, 0.4 g of a fibrous material was dispersed in 40 g of ion-exchanged water to obtain a slurry. The slurry was filtered under reduced pressure using a glass filter (SHIBATA, 25GP100) to obtain a wet web. This wet web was dried in a thermostatic bath for 10 minutes to produce a fibrous thin film-like molded body.

Example 6
A fibrous material is produced in the same manner as in Example 5 except that the step of washing the fiber intermediate is carried out, and a thin-film shaped product is produced by a wet papermaking method using the fibrous material. Six samples were used.

Example 7
Using the fibrous material of Example 2 and polyvinyl alcohol (made by Kuraray, PVA403), which is a synthetic polymer, as a moldable polymer material, a thin film-like molded product was produced by the following method. A sample was used. More specifically, 1 g of 1% PVA403 aqueous solution was added to the dispersion used to obtain the molded body in Example 2 and stirred, and this dispersion was applied to the surface of a 25 μm thick polyethylene terephthalate film. Using a coater, a coating film was formed by applying a wet film thickness of 100 μm. This coating film was dried at room temperature for 2 hours to obtain a desired thin film-like molded body. The content of the fibrous material contained in the molded body was 5% when calculated based on the charged amount.

Example 8
A thin film-like molded body was produced in the same manner as in Example 7 except that the content of the fibrous material was 10% by mass, and this was used as a sample of Example 8.

[Comparative Example 1]
A thin film-like molded product was produced by the casting method in the same manner as in Example 1 except that the cellulose nanofiber obtained in the above [Production method of cellulose nanofiber] was used as it was as a fibrous material. Samples of

[Comparative Example 2]
A thin film-like molded product was produced by the wet papermaking method in the same manner as in Example 5 except that the oxidized cellulose fiber obtained in the above [Production Method of Oxidized Cellulose Fiber] was used as it was as a fibrous material. Two samples were used.

[Comparative Example 3]
A fibrous material was obtained in the same manner as in Example 1 except that natural cellulose fibers (conifer bleached kraft pulp, manufactured by Fletcher Challenge Canada, CSF 650 ml) having a carboxyl group content of less than 0.1 mmol / g were used instead of cellulose nanofibers. A thin film-like molded body was manufactured by the same wet papermaking method as in Example 5 using the fibrous material, and this was used as a sample of Comparative Example 3.

[Comparative Example 4]
A fibrous material was obtained in the same manner as in Example 4 except that natural cellulose fibers having a carboxyl group content of less than 0.1 mmol / g (conifer bleached kraft pulp, Fletcher Challenge Canada, CSF 650 ml) were used instead of cellulose nanofibers. A thin film-like molded body was manufactured by the same wet papermaking method as in Example 5 using the fibrous material, and this was used as a sample of Comparative Example 4.

[Comparative Example 5]
Conductive polymer particles were produced by the following procedure without using cellulose fibers. Specifically, after adding 10 g of ferric chloride dissolved in 100 g of ion-exchanged water to 500 g of ion-exchanged water and stirring for 30 minutes, 10.9 g of pyrrole dissolved in 100 g of ion-exchanged water and 100 g of 2-Naphthalenesulfonic acid (10.9 g) dissolved in ion-exchanged water was added, and polyvinylpyrrolidone (0.5 g) was further added, followed by stirring at room temperature for 12 hours. After the reaction, an emulsion dispersion of particles having a diameter of about 20 nm was obtained. A thin film-like molded product was obtained from the dispersion thus obtained by a casting method in the same manner as in Example 1, but it was impossible to mold due to insufficient strength.

[Comparative Example 6]
A thin film-like molded body was produced in the same manner as in Example 7 except that the fibrous material was not used (the content of the fibrous material was 0% by mass), and this was used as a sample of Comparative Example 6.

[Evaluation]
For the samples (molded bodies) of Examples and Comparative Examples, the surface resistivity and the surface resistivity per conductive polymer content were measured and calculated by the methods described above. Moreover, regarding the fibrous material used as the raw material of each sample, the carboxyl group content, the average fiber diameter, and the dropping rate of the conductive polymer were measured by the above methods. These results are shown in Tables 1 and 2 below.

As is apparent from the results shown in Table 1, the moldings of Examples 1 to 6 produced from the fibrous material of the present invention containing cellulose fibers having a carboxyl group content of 0.1 to 3 mmol / g and a conductive polymer. Each of the bodies has a surface resistivity of 10 ⁷ (Ω / □) or less, Comparative Example 1 containing no conductive polymer, and Comparative Example using cellulose fibers having a carboxyl group content of less than 0.1 mmol / g Compared to 3, it showed higher conductivity. In particular, Examples 1 and 2 using cellulose nanofibers had high conductivity. As is clear from the comparison between Example 1 and Example 4 or the comparison between Example 5 and Example 6, when the fiber intermediate is washed, the content of the conductive polymer decreases, so that the conductivity is reduced. However, the dropout rate of the conductive polymer could be reduced. This is presumably due to the fact that there are many conductive polymers polymerized on the surface of the cellulose fiber and there are few conductive polymers that are physically captured. In Comparative Example 3, since cellulose fibers having a carboxyl group content of less than 0.1 mmol / g are used, the conductivity is expressed by the conductive polymer that is only physically captured. Compared with No. 6 and No. 6, the dropping rate of the conductive polymer is high. In addition, since Comparative Example 4 also uses cellulose fibers having a carboxyl group content of less than 0.1 mmol / g, all the oxidizing agent is washed by the washing step of the fiber intermediate. Almost no polymerization. Further, in Comparative Example 5 containing no cellulose fiber, it was impossible to mold and a molded product was not obtained. Therefore, it can be seen that cellulose fiber is also effective as an aggregate of a conductive polymer.

  As is apparent from the results shown in Table 2, Examples containing the fibrous material of the present invention containing cellulose fibers having a carboxyl group content of 0.1 to 3 mmol / g and a conductive polymer and PVA as a polymer material. The molded bodies of 7 and 8 showed higher electrical conductivity than Comparative Example 6 made of PVA alone without containing a fibrous material. From this result, it can be seen that the fibrous material of the present invention functions as a conductive filler to the molding resin.

Claims (8)

A fibrous material containing a cellulose fiber having a carboxyl group content of 0.1 to 3 mmol / g and a conductive polymer,
The cellulose fibers in a state in which an oxidizing agent is adsorbed into the fibrous product obtained through a step of mixing the monomer corresponding to the conductive polymer polymerization.   The fibrous material according to claim 1, wherein the cellulose fibers are cellulose nanofibers.   The fibrous material according to claim 1 or 2, wherein the conductive polymer is at least one selected from the group consisting of polypyrrole and polyaniline.   Content of the said conductive polymer is 10-90 mass%, The fibrous material as described in any one of Claims 1-3.   The fibrous material according to any one of claims 1 to 4, wherein iron ions are adsorbed on a carboxyl group of the cellulose fiber.   The molded object containing the fibrous material as described in any one of Claims 1-5.   It is a manufacturing method of the fibrous material of Claim 1, Comprising: (i) The process which makes an oxidant adsorb | suck to the said cellulose fiber, and obtains a fiber intermediate, (ii) The said fiber intermediate and a monomer are mixed, A method for producing a fibrous material, comprising a step of polymerizing the monomer with the fiber intermediate to obtain the conductive polymer.   The method for producing a fibrous material according to claim 1, wherein (i) a step of adsorbing an oxidizing agent on the cellulose fiber to obtain a fiber intermediate, (ii) a step of washing the fiber intermediate, and (iii) ) A method for producing a fibrous material, comprising the steps of mixing the fiber intermediate and a monomer and polymerizing the monomer in the fiber intermediate to obtain the conductive polymer.