resin composition

Abstract

The present invention relates to a resin composition for impregnating fibers subjected to tensile stress, and to providing a resin composition that exhibits minimal dripping upon curing. [Solution] A resin composition for impregnating fibers subjected to tensile stress, comprising the following components (A) and (B). Component (A): Modified cellulose fiber having modifying groups via ionic and / or covalent bonds to the anionic groups of anionic-modified cellulose fiber. Component (B): Non-aqueous liquid that is liquid at 25°C and 1 atm.

Description

[Technical Field]

[0001] The present invention relates to a resin composition for impregnating fibers subjected to tensile stress, a fiber-reinforced resin, and a method for producing a fiber-reinforced resin. [Background technology]

[0002] In recent years, technologies with a low environmental impact have come into the spotlight, and against this backdrop, materials using cellulose fibers, a biomass that is abundant in nature, are attracting attention.

[0003] For example, Patent Document 1 proposes a fiber-reinforced plastic comprising a cured epoxy resin composition containing component (A): a bisphenol F type epoxy resin with a softening point of 80°C or higher, component (B): a bisphenol F type epoxy resin with an epoxy equivalent of 250 or less, component (C): a curing agent, and component (D): cellulose nanofibers, along with reinforcing fibers, for the purpose of obtaining a fiber-reinforced composite material having excellent strength and elastic modulus. Patent Document 2 also proposes a fiber-reinforced plastic comprising a resin composition, a composite material containing cellulose nanofibers in a weight ratio of 0.5% to 1.0% relative to the resin composition, and a fiber material, for the purpose of improving the gas permeability of fiber-reinforced plastics. Furthermore, Patent Document 3 proposes a carbon fiber-reinforced composite material comprising carbon fibers, a matrix resin, and specific modified cellulose fibers, for the purpose of providing a carbon fiber-reinforced composite material with excellent dimensional stability. [Prior art documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2018-95675 [Patent Document 2] Japanese Patent Publication No. 2023-69249 [Patent Document 3] Japanese Patent Publication No. 2019-218538 [Patent Document 4] Japanese Patent Application Publication No. 8-176403 [Overview of the initiative] [Problems that the invention aims to solve]

[0005] Known molding methods for FRP (fiber-reinforced plastic) include the filament winding method, in which resin-impregnated reinforced fibers are wound around a mandrel (hollow cylindrical mold) and then cured in a heat-curing furnace to obtain the finished product, and the continuous pultrusion method (pull-trusion method) described in Patent Document 4. Both of these molding methods involve impregnating fibers subjected to tensile stress with a resin composition and then heat-molding, and are suitable for molded products in the shape of tubes and tanks. However, it has been found that with the resin compositions described in Patent Documents 1 and 2, the resin composition may drip during the curing process in these molding methods, resulting in insufficient resin coating of the fibers.

[0006] The present invention relates to a resin composition for impregnating fibers subjected to tensile stress, and to providing a resin composition that exhibits minimal dripping upon curing. [Means for solving the problem]

[0007] The present invention relates to the following [1] to [3]. [1] A resin composition for impregnating fibers subjected to tensile stress, comprising the following components (A) and (B). Component (A): Modified cellulose fiber having modifying groups via ionic and / or covalent bonds to the anionic groups of anionic-modified cellulose fiber. Component (B): Non-aqueous liquid that is liquid at 25°C and 1 atm. [2] A method for producing a fiber-reinforced resin, comprising impregnating fibers subjected to tensile stress with the resin composition described in [1]. [3] A fiber-reinforced resin obtained by the manufacturing method described in [2]. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a resin composition for impregnating fibers subjected to tensile stress, which exhibits minimal dripping upon curing. [Brief explanation of the drawing]

[0009] [Figure 1] This is a schematic diagram illustrating the ratio (D / S) in Test Example 1. [Modes for carrying out the invention]

[0010] When the inventors investigated the above problem, they newly discovered that dripping during curing can be suppressed when a resin composition containing specific modified cellulose fibers and a specific non-aqueous liquid is used. Although the mechanism is not clear, it is presumed that the modified cellulose fibers form a network structure even at high temperatures, suppressing the flow of the non-aqueous liquid. Patent document 3 describes a carbon fiber reinforced composite material using modified cellulose fibers, but it assumes a sheet-like composite material coated using a bar coater, and does not describe its use in a resin composition for impregnating fibers subjected to tensile stress.

[0011] The resin composition of the present invention is a resin composition for impregnating fibers subjected to tensile stress, and contains the following components (A) and (B). Component (A): Modified cellulose fiber having modifying groups via ionic and / or covalent bonds to the anionic groups of anionic-modified cellulose fiber. Component (B): Non-aqueous liquid that is liquid at 25°C and 1 atm.

[0012] 〔fiber〕 The fiber to which tensile stress is applied is not particularly limited, but since it suppresses dripping when cured and has a high resin coating rate, it is preferably a fiber that impregnates the resin composition in a molding method such as the filament winding method or the continuous drawing molding method (pultrusion method). Examples of the type of fiber (reinforcing fiber) that impregnates the resin composition include carbon fiber, glass fiber, aramid fiber, polyethylene fiber, zylon fiber, boron fiber, etc., and carbon fiber is preferred.

[0013] As described above, the filament winding method is a known molding method as a molding method for FRP (fiber reinforced resin). It is a molding method in which a bundle of fibers is aligned, passed through a resin tank to impregnate the resin, then tension is applied to a rotating mandrel (core metal) and continuously wound at a predetermined angle, and then the mandrel is placed in an oven and heated and cured.

[0014] The continuous drawing molding method (pultrusion method) is a known molding method as a molding method for FRP (fiber reinforced resin). A bundle of fibers is pulled out from a bobbin at a low speed, impregnated through a resin tank, then pulled into a mold and heated simultaneously, and continuously cured while being pulled out while passing through the mold. It is a molding method in which a molded product of a certain length is continuously manufactured by cutting with a cutter or the like while pulling out or winding with a winding device.

[0015] The tensile stress applied to the fiber is not particularly limited, but the ratio (D / S) of the sag distance D to the distance S between the supports shown in FIG. 1 is preferably a tensile stress of 0.20 or less, more preferably 0.10 or less, and still more preferably 0.05 or less.

[0016] 〔Carbon Fiber〕 The carbon fiber may be produced by spinning using pitch such as petroleum or coal as a raw material, or may be produced using polyacrylonitrile or rayon as a raw material. In addition, recycled products obtained by recycling the end materials of carbon fiber or carbon fiber recycled products obtained by removing resin from carbon fiber reinforced composite materials can also be used.

[0017] The average fiber diameter of the carbon fibers is preferably 1 to 100 μm, more preferably 3 to 50 μm, and even more preferably 4 to 20 μm. When the average fiber diameter is within this range, processing is easy, and the resulting carbon fiber reinforced composite material exhibits excellent elastic modulus and strength. The average fiber diameter of the carbon fibers can be measured by observation using a scanning electron microscope (SEM), for example, by randomly selecting 50 or more fibers, measuring their lengths, and calculating the average fiber diameter based on the number of fibers.

[0018] The fineness of the carbon fiber is preferably 20 to 4,500 tex, and more preferably 50 to 4,000 tex. Within this fineness range, impregnation with the matrix resin is easy, resulting in a carbon fiber reinforced composite material with excellent elastic modulus and strength. The fineness can be determined by calculating the mass of a long fiber of any length and converting it to the mass per 1,000 m. Typically, carbon fibers with approximately 500 to 60,000 filaments are preferably used.

[0019] [Ingredient (A)] The modified cellulose fibers of component (A) have modifying groups via ionic and / or covalent bonds to the anionic groups of the anionic-modified cellulose fibers. Both the modified cellulose fibers and the anionic-modified cellulose fibers have a cellulose type I crystalline structure due to the use of natural cellulose fibers as raw materials.

[0020] Cellulose type I refers to the crystalline form of natural cellulose, and the degree of crystallinity of cellulose type I refers to the proportion of crystalline material within the total cellulose.

[0021] In the present invention, the degree of crystallinity of the modified cellulose fibers and anion-modified cellulose fibers is preferably 10% or more, more preferably 15% or more, and even more preferably 20% or more, from the viewpoint of improving dispersibility in the resin composition. Furthermore, from the viewpoint of raw material availability, it is preferably 90% or less, more preferably 85% or less, and even more preferably 80% or less. In this specification, the degree of crystallinity of various cellulose fibers is the degree of cellulose type I crystallinity calculated from the diffraction intensity value by X-ray diffraction, and can be measured according to the method described in the examples below. Cellulose type I refers to the crystalline form of natural cellulose, and the degree of cellulose type I crystallinity means the proportion of the crystalline region in the total amount of cellulose fibers. The presence or absence of a cellulose type I crystalline structure can be determined by the presence of a peak at 2θ = 22.6° in X-ray diffraction measurement.

[0022] Anionically modified cellulose fibers are cellulose fibers having one or more anionic groups, selected from the group consisting of carboxyl groups, ()phosphorous groups, and sulfonic acid groups, within their molecule. From the viewpoint of availability and effectiveness, anionically modified cellulose fibers having a carboxyl group as the anionic group (referred to as "oxidized cellulose fibers") are preferred, and anionically modified cellulose fibers in which the hydroxymethyl group (-CH2OH) at the C6 position of the glucose unit constituting the cellulose fiber is selectively converted to a carboxyl group (referred to as "TEMPO-oxidized cellulose fibers") are more preferred. The ion paired with the anionic group (counterion) is preferably a proton.

[0023] The average fiber diameter of anion-modified cellulose fibers is preferably 0.1 μm or more, more preferably 1 μm or more, even more preferably 10 μm or more, and even more preferably 30 μm or more, from the viewpoint of enhancing the mechanical strength of the coating film after curing of the resin composition. Also, from the same viewpoint, it is preferably 100 μm or less, more preferably 70 μm or less, and even more preferably 50 μm or less. The average fiber diameter of various cellulose fibers, such as anion-modified cellulose fibers, can be measured by the method described in the examples below.

[0024] The average fiber length of anion-modified cellulose fibers is preferably 1 μm or more, more preferably 10 μm or more, and even more preferably 100 μm or more, from the viewpoint of enhancing the mechanical strength of the coating film after curing of the resin composition. From a similar viewpoint, it is preferably 10,000 μm or less, more preferably 5,000 μm or less, even more preferably 3,000 μm or less, and even more preferably 2,500 μm or less. The average fiber length of various cellulose fibers, such as anion-modified cellulose fibers, can be measured by the method described in the examples below.

[0025] The average aspect ratio of anionically modified cellulose fibers, i.e., the fiber length / fiber diameter value, is preferably 1 or more, more preferably 2 or more, and even more preferably 3 or more, from the viewpoint of enhancing the mechanical strength of the coating film after curing of the resin composition. Similarly, it is preferably 250 or less, more preferably 200 or less, even more preferably 100 or less, even more preferably 70 or less, and even more preferably 50 or less.

[0026] The anionic group content in anionically modified cellulose fibers is preferably 0.1 mmol / g or more, more preferably 0.4 mmol / g or more, even more preferably 0.6 mmol / g or more, even more preferably 0.7 mmol / g or more, and even more preferably 0.8 mmol / g or more, from the viewpoint of stable micronization and introduction of modifying groups. Furthermore, from the viewpoint of improving handling properties, it is preferably 3.0 mmol / g or less, more preferably 2.5 mmol / g or less, even more preferably 2.0 mmol / g or less, even more preferably 1.9 mmol / g or less, and even more preferably 1.8 mmol / g or less. Note that "anionic group content" refers to the total amount of anionic groups in the glucose portion constituting the cellulose fiber, and is specifically measured by the method described in the examples below.

[0027] The preferred ranges for the average fiber diameter, average fiber length, average aspect ratio, and degree of crystallinity of modified cellulose fibers are the same as those for anionically modified cellulose fibers.

[0028] From the viewpoint of improving dispersibility, the amount of modifying groups bound to the modified cellulose fibers is preferably 0.01 mmol / g or more, more preferably 0.1 mmol / g or more, and even more preferably 0.2 mmol / g or more. Similarly, from the same viewpoint, it is preferably 3 mmol / g or less, more preferably 2 mmol / g or less, and even more preferably 1.8 mmol / g or less.

[0029] From the viewpoint of improving dispersibility, the rate of introduction of modifying groups in modified cellulose fibers is preferably 5 mol% or more, more preferably 10 mol% or more, and even more preferably 20 mol% or more. Similarly, from the same viewpoint, it is preferably 100 mol% or less, more preferably 90 mol% or less, and even more preferably 80 mol% or less.

[0030] The amount and introduction rate of modifying groups can be adjusted by the type and amount of modifying group added, the reaction temperature, the reaction time, the type of solvent, etc. The amount (mmol / g) and introduction rate (mol%) of modifying groups refer to the amount and percentage of modifying groups introduced (bound) to anionic groups in modified cellulose fibers. For example, when the anionic group is a carboxyl group, the amount and introduction rate of modifying groups in modified cellulose fibers can be calculated by the method described in the examples below.

[0031] From the viewpoint of improving the dispersibility of the modified cellulose fibers, the amount of glucose in the modified cellulose fibers is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more. On the other hand, from the viewpoint of handling during manufacturing, it is preferably 70% by mass or less, more preferably 60% by mass or less, and even more preferably 50% by mass or less.

[0032] In this specification, "glucose portion" refers to the portion consisting of glucose units in various types of cellulose fibers. In the case of unmodified cellulose fibers, it refers to the entire glucose unit; in the case of anionically modified cellulose fibers, it refers to the entire glucose unit including the anionic group attached to the glucose unit; and in the case of modified cellulose fibers, it refers to the entire glucose unit excluding the modifying group attached to the glucose unit. That is, in this specification, glucose units also include glucose units in which a hydroxymethyl group has been converted to a carboxyl group.

[0033] The method for producing modified cellulose fibers can be any known method without particular limitation, as long as it allows for the introduction of modifying groups into the anionically modified cellulose fibers described above.

[0034] A method for producing modified cellulose fibers may include, for example, a step of introducing anionic groups into raw cellulose fibers to obtain anionically modified cellulose fibers, and a step of introducing modifying groups into anionically modified cellulose fibers to obtain modified cellulose fibers.

[0035] From an environmental perspective, it is preferable to use natural cellulose fibers as raw materials. Examples of natural cellulose fibers include wood pulp such as coniferous pulp and hardwood pulp; cotton pulp such as cotton linters and cotton lint; non-wood pulp such as straw pulp and bagasse pulp; and bacterial cellulose. One of these can be used alone or in combination of two or more.

[0036] Examples of anionic groups introduced into the cellulose fibers used as raw materials include carboxyl groups, ()phosphorous groups, and sulfonic acid groups. Methods for introducing a carboxyl group as an anionic group into cellulose fibers include, for example, oxidizing the hydroxyl group of the cellulose fiber to convert it into a carboxyl group, or reacting the hydroxyl group of the cellulose fiber with at least one selected from the group consisting of compounds having a carboxyl group, acid anhydrides of compounds having a carboxyl group, and derivatives thereof.

[0037] One method for oxidizing the hydroxyl groups of cellulose fibers is described in Japanese Patent Publication No. 2015-143336 or Japanese Patent Publication No. 2015-143337, which involves reacting 2,2,6,6-tetramethyl-1-piperidine-N-oxyl (TEMPO) as a catalyst with an oxidizing agent such as sodium hypochlorite and a bromide such as sodium bromide, using cellulose fibers as a raw material. By oxidizing cellulose fibers using TEMPO as a catalyst, anionically modified cellulose fibers (referred to as "TEMPO-oxidized cellulose fibers") can be obtained in which the hydroxymethyl group at the C6 position of glucose in the cellulose fiber constituent unit is selectively converted to a carboxyl group.

[0038] Methods for introducing ()phosphorous groups as anionic groups into cellulose fibers include mixing powder or aqueous solution of ()phosphorous or ()phosphorous derivatives with dry or wet cellulose fibers, or adding aqueous solution of ()phosphorous or ()phosphorous derivatives to a dispersion of cellulose fibers. When these methods are employed, generally, after mixing or adding powder or aqueous solution of ()phosphorous or ()phosphorous derivatives), dehydration treatment and heat treatment are performed.

[0039] One method for introducing phosphate groups as anionic groups into cellulose fibers is described in Japanese Patent Publication No. 7196051, which involves impregnating raw cellulose fibers with a mixed aqueous solution of ammonium dihydrogen phosphate and urea to phosphate esterify the hydroxyl groups of the cellulose fibers. Methods for introducing sulfonic acid groups as anionic groups into cellulose fibers include adding sulfuric acid to the cellulose fibers and heating them.

[0040] The modifying group is introduced by the reaction of a compound for introducing the modifying group (referred to herein as the "modifying compound") with an anionically modified cellulose fiber. Thus, the modified cellulose fiber of component (A) has the modifying group via ionic and / or covalent bonds.

[0041] When the modifying group is bonded to an anionic group in an anionic-modified cellulose fiber, the bond between the modifying group and the anionic-modified cellulose fiber is either ionic or covalent. In the case of an ionic bond, the modifying compound having a cationic group bonds to the anionic group via electrostatic interaction. In the case of a covalent bond, the two are bonded via ester bonds, amide bonds, etc. In particular, when the anionic group is a carboxyl group, the bond is formed via ester bonds, amide bonds, carbonate bonds, urethane bonds, etc.

[0042] When the modifying group is bonded to an anionic group, one method is to bond the modifying group to the cellulose fiber by an ionic bond, which can be achieved by known methods. For example, the method described in Japanese Patent Application Publication No. 2015-143336 can be used, in which the modifying group and the anionic group are bonded by an ionic bond. When the anionic group is a carboxyl group, one method is to bond the modifying group to the cellulose fiber by covalent bonds, which can be achieved by known methods. For example, the method described in Japanese Patent Application Publication No. 2015-143337 can be used, in which the modifying group and the anionic group are bonded by an amide bond, which is a type of covalent bond.

[0043] Therefore, one embodiment in which the modifying group is bonded to an anionic group is that the modifying group in the modified cellulose fiber of component (A) is bonded to the glucose constituting the cellulose via ionic bonds and / or amide bonds.

[0044] Examples of modifying groups include (a) hydrocarbon groups and (b) polymer groups.

[0045] (a) hydrocarbon group Examples of hydrocarbon groups include monovalent hydrocarbon groups, such as chain-type saturated hydrocarbon groups, chain-type unsaturated hydrocarbon groups, cyclic saturated hydrocarbon groups, and (heterocyclic) aromatic hydrocarbon groups. The hydrocarbon group has 1 or more carbon atoms, preferably 3 or more, more preferably 8 or more, and even more preferably 10 or more, while preferably 30 or less, more preferably 22 or less, and even more preferably 18 or less. The hydrocarbon group may have substituents as described later, and a portion of the hydrocarbon group may be substituted with hydrogen nitride groups.

[0046] Specific examples of chain-type saturated hydrocarbon groups include, for example, methyl group, ethyl group, propyl group, isopropyl group, butyl group, sec-butyl group, tert-butyl group, isobutyl group, pentyl group, tert-pentyl group, isopentyl group, hexyl group, isohexyl group, heptyl group, octyl group, 2-ethylhexyl group, nonyl group, decyl group, dodecyl group, tridecyl group, trioctyl group, tetradecyl group, octadecyl group, docosyl group, octacosanyl group, and the like.

[0047] Specific examples of chain-type unsaturated hydrocarbon groups include, for example, ethylene, propylene, butene, isobutene, isoprene, pentene, hexene, heptene, octene, nonene, decene, dodecene, tridecene, tetradecene, and octadecene.

[0048] Specific examples of cyclic saturated hydrocarbon groups include, for example, cyclopropane, cyclobutyl, cyclopentane, cyclohexyl, cycloheptyl, cyclooctyl, cyclononyl, cyclodecyl, cyclododecyl, cyclotridecyl, cyclotetradecyl, and cyclooctadecyl groups.

[0049] Aromatic hydrocarbon groups are selected from the group consisting of, for example, aryl groups and aralkyl groups.

[0050] Examples of aryl groups include phenyl, naphthyl, anthryl, phenanthryl, biphenyl, triphenyl, terphenyl groups, and groups in which these groups are substituted with substituents described later.

[0051] Examples of aralkyl groups include benzyl, dibenzyl, trityl, phenethyl, phenylpropyl, phenylpentyl, phenylhexyl, phenylheptyl, phenyloctyl, and groups in which the aromatic groups of these groups are further substituted with substituents.

[0052] (b) Polymer group A polymer group is a functional group containing a polymer structure. The molecular weight of the polymer group is preferably 100 or more, more preferably 200 or more, more preferably 300 or more, more preferably 400 or more, even more preferably 600 or more, even more preferably 1,000 or more, and even more preferably 1,500 or more, from the viewpoint of improving dispersion stability. From a similar viewpoint, it is preferably 10,000 or less, more preferably 7,000 or less, even more preferably 5,000 or less, even more preferably 4,000 or less, even more preferably 3,500 or less, and even more preferably 2,500 or less.

[0053] From the viewpoint of improving dispersion stability, the polymer group is preferably a functional group having a repeating structure linked by an oxygen atom, more preferably a functional group having a repeating structure linked by an oxygen atom, such as a polyoxyalkylene structure (alkylene oxide chain) or a polysiloxane structure (silicone chain), more preferably a functional group having a polyoxyalkylene structure, and even more preferably an alkoxypolyoxyalkylene group.

[0054] (b-1) Polysiloxane structure (silicone chain) A polysiloxane structure (silicone chain) is a structure in which siloxane bonds form the main chain, and which may also contain alkylene groups. The polysiloxane structure may also have substituents as described later.

[0055] (b-2) Polyoxyalkylene structure (alkylene oxide chain) The polyoxyalkylene structure (alkylene oxide chain) is preferably a (co)polymer structure of one or more oxyalkylenes selected from oxyalkylenes having 2 to 8 carbon atoms, more preferably a (co)polymer structure of one or more oxyalkylenes selected from oxyalkylenes having 2 to 4 carbon atoms, even more preferably a (co)polymer structure of one or two oxyalkylenes selected from ethylene oxide (EO) and propylene oxide (PO), and even more preferably a copolymer structure (also called an (EO / PO) structure) in which ethylene oxide (EO) and propylene oxide (PO) are polymerized randomly or in blocks.

[0056] For example, a polyoxyalkylene structure can be represented by the following formula:

[0057] [ka]

[0058] (In the formula, R 1 represents a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or a -CH2CH(CH3)NH2 group. EO and PO are present randomly or in blocks, where a is 0 or a positive number representing the average number of moles of EO added, and b is 0 or a positive number representing the average number of moles of PO added. However, a and b cannot be 0 at the same time.) Examples of groups include those shown by ).

[0059] R 1 When is a linear or branched alkyl group having 1 to 6 carbon atoms, the alkyl group is preferably a methyl group, an ethyl group, an n-propyl group, and a sec-propyl group. 1 It may be a hydrogen atom.

[0060] From the viewpoint of improving dispersion stability, a is preferably 0 or more, more preferably 1 or more, even more preferably 3 or more, even more preferably 6 or more, even more preferably 11 or more, even more preferably 15 or more, even more preferably 20 or more, even more preferably 25 or more, and even more preferably 30 or more. From a similar viewpoint, it is preferably 100 or less, more preferably 70 or less, even more preferably 60 or less, even more preferably 50 or less, and even more preferably 40 or less.

[0061] From the viewpoint of improving dispersion stability, b is preferably 0 or greater, more preferably 1 or greater, even more preferably 3 or greater, and still more preferably 5 or greater. From a similar viewpoint, it is preferably 50 or less, more preferably 40 or less, even more preferably 30 or less, even more preferably 25 or less, even more preferably 20 or less, even more preferably 15 or less, and still more preferably 10 or less.

[0062] In the above formula, a+b represents the average number of moles added in total of EO and PO, and is preferably 4 or more, more preferably 6 or more, more preferably 8 or more, and from a similar viewpoint, preferably 100 or less, more preferably 70 or less.

[0063] Examples of the alkylene group having 1 to 3 carbon atoms include the methylene group, the ethylene group, and the propylene group.

[0064] The PO content (mol%) in the (EO / PO) chain can be calculated based on a and b above, specifically from b × 100 / (a ​​+ b). From the viewpoint of further improving dispersibility, the PO content is preferably 1 mol% or more, more preferably 5 mol% or more, even more preferably 7 mol% or more, and even more preferably 10 mol% or more. From a similar viewpoint, it is preferably 100 mol% or less, more preferably 90 mol% or less, even more preferably 85 mol% or less, even more preferably 75 mol% or less, even more preferably 60 mol% or less, even more preferably 50 mol% or less, even more preferably 40 mol% or less, and even more preferably 30 mol% or less.

[0065] From the viewpoint of improving dispersion stability, the formula weight (molecular weight) of the polyoxyalkylene structure is preferably 100 or more, more preferably 200 or more, even more preferably 300 or more, even more preferably 500 or more, even more preferably 1,000 or more, and even more preferably 1,500 or more. From a similar viewpoint, it is preferably 10,000 or less, more preferably 7,000 or less, even more preferably 5,000 or less, even more preferably 4,000 or less, even more preferably 3,500 or less, and even more preferably 2,500 or less.

[0066] (c) Further substituents The modifying group may have further substituents. Examples of substituents include alkoxy groups having 1 to 6 carbon atoms, such as methoxy, ethoxy, propoxy, isopropoxy, butoxy, isobutoxy, sec-butoxy, tert-butoxy, pentyloxy, isopentyloxy, and hexyloxy groups; methoxycarbonyl, ethoxycarbonyl, propoxycarbonyl, isopropoxycarbonyl, butoxycarbonyl, isobutoxycarbonyl, and sec-butoxycarbonyl groups. Examples include alkoxy-carbonyl groups with 1 to 6 carbon atoms, such as tert-butoxycarbonyl, pentyloxycarbonyl, and isopentyloxycarbonyl groups; halogen atoms such as fluorine, chlorine, bromine, and iodine atoms; acyl groups with 1 to 6 carbon atoms, such as acetyl and propionyl groups; aralkyl groups; aralkyloxy groups; alkylamino groups with 1 to 6 carbon atoms; dialkylamino groups with 1 to 6 carbon atoms in the alkyl group; and hydroxyl groups.

[0067] Modifying compounds include those having the above-mentioned modifying group and capable of binding to anionically modified cellulose fibers, from the viewpoint of improving dispersion stability. When TEMPO-oxidized cellulose fibers are used as anion-modified cellulose fibers, preferred modifying compounds include compounds having a modifying group and a cationic group, and more preferably compounds having a modifying group and an amino group or a quaternary ammonium group. Preferred examples of modifying compounds include amine compounds having a modifying group and at least one amino group in the molecule, from the viewpoint of improving dispersion stability. More specifically, examples include amine compounds having a hydrocarbon group, amine compounds having a polysiloxane structure, and amine compounds having a polyoxyalkylene structure.

[0068] Such amine compounds may be primary amines, secondary amines, tertiary amines, or quaternary ammonium compounds. From the viewpoint of reactivity, the anionic component of the quaternary ammonium compound is preferably a halogen ion such as chloride ions or bromide ions, bisulfate ions, perchlorate ions, tetrafluoroborate ions, hexafluorophosphonate ions, trifluoromethanesulfonate ions, or hydroxy ions.

[0069] (a) Amine compounds having a hydrocarbon group Specific examples of amine compounds having hydrocarbon groups include primary to tertiary amines such as ethylamine, diethylamine, triethylamine, propylamine, dipropylamine, butylamine, dibutylamine, hexylamine, 2-ethylhexylamine, dihexylamine, trihexylamine, octylamine, dioctylamine, trioctylamine, dodecylamine, didodecylamine, stearylamine, distearylamine, monoethanolamine, diethanolamine, triethanolamine, oleylamine, aniline, octadecylamine, dimethylbehenylamine, benzylamine, dibenzylamine, tritylamine, naphthylamine, imidazole, 2-methylimidazole, 2-ethylimidazole, 2-phenylimidazole, 2-ethyl-4-methylimidazole, 2-phenyl-4-methylimidazole, and 1-(3-aminopropyl)imidazole.

[0070] Examples of quaternary ammonium compounds include tetramethylammonium hydroxide (TMAH), tetraethylammonium hydroxide (TEAH), tetraethylammonium chloride, tetrapropylammonium hydroxide (TPAH), tetrabutylammonium hydroxide (TBAH), tetrabutylammonium chloride, lauryltrimethylammonium chloride, dilauryldimethylammonium chloride, stearyltrimethylammonium chloride, distearyldimethylammonium chloride, cetyltrimethylammonium chloride, and alkylbenzyldimethylammonium chloride.

[0071] Amine compounds having hydrocarbon groups can be obtained using commercially available products or prepared according to known methods.

[0072] Furthermore, hydrocarbon compounds having cationic groups may also have substituents. Specific examples of substituents include those described in "(c) Further substituents" above.

[0073] (b-1) Amine compounds having a polysiloxane structure Examples of such amine compounds include those having a structure in which an amino group is bonded to a polysiloxane structure via an alkylene group or the like. In this specification, such amine compounds may be referred to as "amino-modified silicones." Amino-modified silicones can be used commercially or prepared according to known methods. One type of amino-modified silicone may be used, or two or more types may be used.

[0074] In terms of performance, amino-modified silicones include Momentive Performance Materials' TSF4703 (kinematic viscosity: 1000, amino equivalent: 1600) and TSF4708 (kinematic viscosity: 1000, amino equivalent: 2800), and Toray Dow Corning Silicone's SS-3551 (kinematic viscosity: 1000, amino equivalent: 1600), SF8457C (kinematic viscosity: 1200, amino equivalent: 1800), SF8417 (kinematic viscosity: 1200, amino equivalent: 1700), and BY16-209 (kinematic viscosity: 500, amino equivalent: 1800), B Preferred products include Y16-892 (kinematic viscosity: 1500, amino equivalent: 2000), BY16-898 (kinematic viscosity: 2000, amino equivalent: 2900), FZ-3760 (kinematic viscosity: 220, amino equivalent: 1600), KF8002 (kinematic viscosity: 1100, amino equivalent: 1700), KF867 (kinematic viscosity: 1300, amino equivalent: 1700), KF-864 (kinematic viscosity: 1700, amino equivalent: 3800), BY16-213 (kinematic viscosity: 55, amino equivalent: 2700), and BY16-853U (kinematic viscosity: 14, amino equivalent: 450) from Shin-Etsu Chemical Co., Ltd. (In parentheses, kinematic viscosity is measured at 25°C (unit: mm) 2 The value is expressed as ( / s), and the unit of amino equivalent is g / mol.

[0075] (b-2) Amine compounds having a polyoxyalkylene structure In amine compounds, it is preferable that the polyoxyalkylene structure and the nitrogen atom of the amine compound are bonded directly or via a linking group. The linking group is preferably a hydrocarbon group, and more preferably an alkylene group having 1 to 6 carbon atoms, and more preferably 1 to 3 carbon atoms. Examples of such alkylene groups include ethylene and propylene groups.

[0076] Examples of amine compounds having a polyoxyalkylene structure include the following formula (i):

[0077] [ka]

[0078] Examples of compounds are shown in formula (i). 1 a and b are R in the formula that shows an example of the polyoxyalkylene structure mentioned above. 1 , is the same as a and b. Amine compounds having a polyoxyalkylene structure are compounds for introducing modifying groups represented by the polyoxyalkylene structure, and can be prepared according to known methods. For example, ethylene oxide and propylene oxide can be added in desired amounts to a propylene glycol alkyl ether, and then the hydroxyl group terminus can be aminated. If necessary, the alkyl ether can be cleaved with an acid to form a hydrogen atom at the terminus. Methods for producing these compounds can be found in Japanese Patent Publication No. 3-181448, and details of such amine compounds are described, for example, in Japanese Patent No. 6105139.

[0079] Amine compounds having a polyoxyalkylene structure can preferably be commercially available, for example. Specific examples of amine compounds that may have a hydrocarbon group and are accompanied by the aforementioned EO chain or PO chain include SUNBRIGHT MEPA-10H, SUNBRIGHT MEPA-20H, SUNBRIGHT MEPA-50H, SUNBRIGHT MEPA-10T, SUNBRIGHT MEPA-12T, SUNBRIGHT MEPA-20T, SUNBRIGHT MEPA-30T, SUNBRIGHT MEPA-40T, etc., manufactured by NOF Corporation.

[0080] Specific examples of amine compounds that may have a hydrocarbon group and are associated with the aforementioned EO / PO chain include Jeffamine M-2070, Jeffamine M-2005, Jeffamine M-2095, Jeffamine M-1000, Jeffamine M-600, Surfoamine B200, Surfoamine L100, Surfoamine L200, Surfoamine L207, Surfoamine L300, Surfoamine B-100, XTJ-501, XTJ-506, XTJ-507, XTJ-508, M3000, Jeffamine ED-600, Jeffamine ED-900, Jeffamine ED-2003, Jeffamine D-230, Jeffamine D-400, Jeffamine D-2000, Jeffamine D-4000, XTJ-510, and Jeffamine, all manufactured by Huntsman. Examples include T-3000, Jeffamine T-5000, XTJ-502, XTJ-509, and XTJ-510. These may be used individually or in combination of two or more types.

[0081] After the introduction of the modifying group, post-treatment may be performed as appropriate to remove unreacted compounds, etc. Examples of post-treatment methods include filtration, centrifugation, and dialysis.

[0082] By micronizing the raw materials—cellulose fibers, anionically modified cellulose fibers, or modified cellulose fibers—micrometer-scale cellulose fibers can be micronized to the nanometer scale. Reducing the average fiber diameter to nanometer size improves dispersibility, which is preferable.

[0083] The average fiber diameter of the micronized cellulose fibers, anion-modified cellulose fibers, or modified cellulose fibers (hereinafter referred to as "micronized fibers") is preferably 0.1 nm or more, more preferably 1 nm or more, and even more preferably 2 nm or more, from the viewpoint of enhancing the mechanical strength of the coating film after curing of the resin composition. Furthermore, the average fiber diameter of the micronized fibers is preferably 300 nm or less, more preferably 200 nm or less, even more preferably 150 nm or less, even more preferably 120 nm or less, and even more preferably 100 nm or less, from the viewpoint of handling ease during manufacturing.

[0084] From the viewpoint of enhancing the mechanical strength of the coating film after curing of the resin composition, the average fiber length of the finely milled fibers is preferably 10 nm or more, more preferably 30 nm or more, even more preferably 50 nm or more, and even more preferably 150 nm or more. Furthermore, from the viewpoint of handling ease during manufacturing, the average fiber length of the finely milled fibers is preferably 1000 nm or less, more preferably 500 nm or less, and even more preferably 300 nm or less.

[0085] The average aspect ratio of the finely milled fibers is preferably 1 or more, more preferably 5 or more, even more preferably 10 or more, and even more preferably 20 or more, from the viewpoint of enhancing the mechanical strength of the coating film after curing of the resin composition. Furthermore, the average aspect ratio of the finely milled fibers is preferably 300 or less, more preferably 250 or less, even more preferably 200 or less, and even more preferably 100 or less, from the viewpoint of handling during manufacturing.

[0086] For the micronization process, known micronization methods can be employed. For example, to obtain micronized modified cellulose fibers with an average fiber diameter of nanometer size, a processing method using a grinder such as a muscoloider or a processing method using a high-pressure homogenizer in a medium can be carried out.

[0087] In addition to high-pressure homogenizers, other known dispersers are also suitably used in the micronization process. For example, dissociators, beaters, low-pressure homogenizers, grinders, mascolloiders, cutter mills, ball mills, jet mills, short-screw extruders, twin-screw extruders, ultrasonic stirrers, and household juicer mixers can be used. Furthermore, the solid content concentration of the modified cellulose fibers in the micronization process is preferably 50% by mass or less.

[0088] In the present invention, various cellulose fibers, namely raw cellulose fibers, anion-modified cellulose fibers, modified cellulose fibers, and finely milled modified cellulose fibers, may be subjected to a shortening treatment. By performing such a shortening treatment, the dispersibility of the finely milled modified cellulose fibers can be improved. The short fiber treatment can be carried out by subjecting the target cellulose fibers to one or more treatment methods selected from the group consisting of (i) alkali treatment, (ii) acid treatment, (iii) heat treatment, ultraviolet treatment, electron beam treatment, mechanical treatment, and enzymatic treatment.

[0089] [Component (B)] Component (B) in this invention is a non-aqueous liquid that is liquid at 25°C and 1 atmosphere. A non-aqueous liquid is a liquid other than water.

[0090] The relative permittivity of a non-aqueous liquid that is liquid at 25°C and 1 atm is preferably 50 or less, more preferably 20 or less, and even more preferably 10 or less. The relative permittivity can be measured using a dielectric meter (for example, a BI-871 (manufactured by Brookhaven Instruments)) at a frequency of 10 kHz.

[0091] Examples of non-aqueous liquids include non-aqueous resins and organic solvents. Non-aqueous liquids may be used alone or in combination of two or more types.

[0092] As the non-aqueous resin, a curable resin is preferred. Examples of curable resins include thermosetting resins and photocurable resins. Specific examples include epoxy resins, urethane resins, acrylic resins, vinyl chloride resins, phenoxy resins, phenolic resins, urea resins, melamine resins, polyimide resins, silicone resins, unsaturated polyester resins, diallyl phthalate resins, and rubber-based resins. Among these, epoxy resins, urethane resins, and acrylic resins are preferred from the viewpoint of availability. When incorporating a non-aqueous resin, it is incorporated as a monomer and / or prepolymer.

[0093] Specific examples of organic solvents include alcohols such as methanol, ethanol, propanol, 2-methoxyethanol (methyl cellosolve), 2-ethoxyethanol (ethyl cellosolve), and 1-methoxy-2-propanol (PGME); tetrahydrofuran (THF), diethyl ether, ethylene glycol, and propylene glycol; ketones such as acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone; and ethyl acetate, butyl acetate, and ethylene glycol monoethyl ether acetate (ethyl cellosolve acetate). Examples include esters such as diethylene glycol monomethyl ether acetate (carbitol acetate) and propylene glycol monomethyl ether acetate (PGMEA); saturated or unsaturated hydrocarbons; aromatic hydrocarbons such as benzene, toluene, and xylene; halogenated hydrocarbons such as methylene chloride and chloroform; lower alkyl ethers; and polar solvents such as N,N-dimethylformamide (DMF), N,N-dimethylacetamide, 1,3-dimethyl-2-imidazolidinone (DMI), and dimethyl sulfoxide. These can be used individually or in combination of two or more.

[0094] [Hardening agent] The resin composition may contain a curing agent. Depending on the type of non-aqueous resin used, a known curing agent can be selected and used.

[0095] When the non-aqueous resin is an epoxy resin, the curing agents used for epoxy resins include compounds that perform stoichiometric reactions, such as aliphatic polyamines, aromatic polyamines, dicyandiamides, polycarboxylic acids, polycarboxylic acid hydrazides, acid anhydrides, polymer captans, and polyphenols, as well as compounds that act catalytically, such as imidazoles, Lewis acid complexes, and onium salts. When compounds that perform stoichiometric reactions are used, curing accelerators such as various amines, imidazoles, Lewis acid complexes, onium salts, and phosphines can be used.

[0096] When the non-aqueous resin is a urethane resin, examples of curing agents commonly used for urethane resins include aromatic isocyanates.

[0097] The amount of curing agent in this invention is not particularly limited, and an appropriate amount may be used depending on the type of curing agent.

[0098] [Other ingredients] The resin composition may optionally contain known components such as pigments, dyes, polymerization initiators, plasticizers, stabilizers, and lubricants. The amount of such components is not particularly limited, and appropriate amounts may be used as needed.

[0099] [Composition of each component in the resin composition] The resin composition according to the present invention can be produced by mixing the above-mentioned components (A) and (B), and other components as needed. Therefore, the resin composition according to the present invention is made by blending the above-mentioned components (A) and (B), and other components as needed.

[0100] The content of component (A) in the resin composition is preferably 0.1% by mass or more, more preferably 0.2% by mass or more, and even more preferably 0.5% by mass or more, from the viewpoint of enhancing the mechanical strength of the coating film after curing of the resin composition. On the other hand, from the viewpoint of handling during manufacturing, it is preferably 10.0% by mass or less, more preferably 7.0% by mass or less, and even more preferably 5.0% by mass or less.

[0101] The content of component (A) per 100 parts by mass of component (B) in the resin composition is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.5 parts by mass or more, from the viewpoint of enhancing the mechanical strength of the coating film after curing of the resin composition. On the other hand, from the viewpoint of handling during manufacturing, it is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less.

[0102] The content of the glucose portion of component (A) in the resin composition is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and even more preferably 0.2% by mass or more, from the viewpoint of enhancing the mechanical strength of the coating film after curing of the resin composition, while from the viewpoint of improving the dispersibility of the modified cellulose fibers, it is preferably 10% by mass or less, more preferably 7% by mass or less, and even more preferably 5% by mass or less.

[0103] The content of the glucose portion of component (A) per 100 parts by mass of component (B) in the resin composition is preferably 0.01 parts by mass or more, more preferably 0.1 parts by mass or more, and even more preferably 0.2 parts by mass or more, from the viewpoint of improving the dispersibility of the modified cellulose fibers, while from the viewpoint of handling during manufacturing, it is preferably 10 parts by mass or less, more preferably 7 parts by mass or less, and even more preferably 5 parts by mass or less.

[0104] From the viewpoint of handling ease during manufacturing, the content of component (B) in the resin composition is preferably 40% by mass or more, more preferably 50% by mass or more, and even more preferably 80% by mass or more. On the other hand, from the viewpoint of enhancing the mechanical strength of the coating film after curing of the resin composition, the content of component (B) in the resin composition is preferably 95% by mass or less, more preferably 90% by mass or less.

[0105] The resin composition may contain water. From the viewpoint of enhancing the mechanical strength of the coating film after curing the resin composition, a low water content is preferable, preferably 1% by mass or less, more preferably 0.5% by mass or less, and even more preferably 0.1% by mass or less.

[0106] The resin composition of the present invention exhibits minimal dripping when impregnated into fibers subjected to tensile stress and cured. Accordingly, the present invention also provides a method for producing a fiber-reinforced resin by impregnating fibers subjected to tensile stress with the resin composition of the present invention, and a fiber-reinforced resin obtained by said production method. Furthermore, the present invention also provides a method for suppressing dripping when impregnating fibers subjected to tensile stress with the resin composition of the present invention. The curing temperature (setting temperature of the curing furnace) is, for example, 50°C or higher, and the temperature at which the drip-suppressing effect of the present invention contributes most significantly is preferably 80°C or higher, more preferably 100°C or higher, and even more preferably 130°C or higher.

[0107] [Fiber-reinforced resin] The fiber-reinforced resin of the present invention is obtained by a method for producing fiber-reinforced resins, in which the resin composition of the present invention is impregnated into fibers subjected to the above-mentioned tensile stress, and is preferably obtained by a filament winding method or a continuous pultrusion method. As described above, the fiber-reinforced resin of the present invention is preferable because it suppresses dripping during curing and has a high resin coverage rate. Fiber-reinforced resins obtained by a filament winding method or a continuous pultrusion method are particularly useful for applications such as pipes, round bars, pressure vessels, fishing rods, and golf shafts.

[0108] The resin coating rate of the fiber-reinforced resin of the present invention is preferably 91% or more, more preferably 92% or more, and even more preferably 93% or more. The resin coating rate is measured by the method described in the examples below. [Examples]

[0109] The present invention will be specifically described below with reference to examples. The following examples are merely illustrative of the present invention and do not imply any limitations. "Normal pressure" refers to a state without pressurization or depressurization, and "room temperature" refers to 25°C.

[0110] [Average fiber diameter and average fiber length of (shortened) anion-modified cellulose fibers] Deionized water was added to the cellulose fibers to be measured or a suspension containing the cellulose fibers to be measured to prepare a dispersion with a content of 0.01% by mass. This dispersion was measured using a wet dispersion type image analysis particle size distribution analyzer (Jusco International Co., Ltd., product name: IF-3200) under the following conditions: front lens: 2x, telecentric zoom lens: 1x, image resolution: 0.835 μm / pixel, syringe inner diameter: 6515 μm, spacer thickness: 500 μm, image recognition mode: ghost, threshold: 8, analysis sample volume: 1 mL, sampling: 15%. The length of the short axis when the cellulose fiber is approximated as a rectangle was defined as the fiber diameter, and the length of the long axis was defined as the fiber length. These values ​​were measured for 100 cellulose fibers, and the average value was calculated.

[0111] [Average fiber diameter and average fiber length of cellulose fibers after micronization treatment] Deionized water was added to the cellulose fibers to be measured or a dispersion containing the cellulose fibers to be measured to prepare a dispersion with a cellulose fiber content of 1% by mass. After adjusting the pH to 9 with sodium hydroxide, the dispersion was treated five times at 150 MPa using a high-pressure homogenizer (NanoVeta L-ES, manufactured by Yoshida Machinery Industry Co., Ltd.). Deionized water was added to the dispersion so that the cellulose fiber content in the dispersion was 0.01% by mass. The dispersion was dropped onto mica, water droplets were removed with air, and the sample was dried. This sample was then measured in dynamic force mode using an atomic force microscope (AFM) (AFM-5100N, manufactured by Hitachi High-Tech Corporation; probe used was SI-DF20P2, manufactured by Hitachi High-Tech Corporation). At that time, more than 100 cellulose fibers were extracted from the microscope image in which the cellulose fibers could be confirmed, and the average fiber diameter was calculated from the height of these fibers. The average fiber length was calculated from the distance in the direction of the fibers.

[0112] [Anionic group content of anionic-modified cellulose fibers] A 0.5 g dry weight of the cellulose fiber to be measured was placed in a beaker, and deionized water or a methanol / deionized water = 2 / 1 (volume ratio) mixed solvent was added to make a total volume of 55 mL. 5 mL of 0.01 M sodium chloride aqueous solution was then added to prepare a dispersion. The dispersion was stirred until the cellulose fiber was sufficiently dispersed. 0.1 M hydrochloric acid was added to the dispersion to adjust the pH to 2.5-3. Using an automatic titrator (Toa DKK Co., Ltd., AUT-701), 0.05 M sodium hydroxide aqueous solution was added dropwise to the dispersion with a waiting time of 60 seconds, and the conductivity and pH values ​​were measured every minute. Measurements were continued until the pH reached approximately 11, and a conductivity curve was obtained. From this conductivity curve, the amount of sodium hydroxide titration was determined, and the anionic group content of the cellulose fiber was calculated using the following formula. Anionic group content (mmol / g) = [Titration volume of sodium hydroxide aqueous solution (mL) × Concentration of sodium hydroxide aqueous solution (0.05M)] / [Mass of cellulose fiber to be measured (0.5g)]

[0113] [Amount of modifying groups attached to and introduction rate of modified cellulose fibers] The amount of modifying groups attached to modified cellulose fibers was determined by the following IR measurement method, and the amount of attachment and the introduction rate were calculated using the following formula. Specifically, the IR measurement involved measuring the infrared absorption spectrum of the dried cellulose fibers to be measured using an infrared absorption spectrometer (IR) (Thermo Fisher Scientific, Nicolet 6700) by the ATR method, and the amount of attachment and the introduction rate of the modifying groups were calculated using formula A. The following shows the case where the anionic group is a carboxyl group, i.e., the case of oxidized cellulose fibers. The following "1720 cm" -1 The peak intensity is derived from the carbonyl group. For anionic groups other than carboxyl groups, the wavenumber value should be appropriately changed to calculate the amount of modifying group bonded and the rate of introduction. <Formula A> Amount of modifying group attached (mmol / g) = a × (bc) ÷ b a: Carboxy group content of oxidized cellulose fibers (mmol / g) b: 1720 cm of oxidized cellulose fiber -1 Peak intensity c: Peak intensity of the modified cellulose fiber at 1720 cm -1 of <Formula B> Introduction rate of the modifying group (mol%) = 100 × f / g f: Amount of the modifying group bonded (mmol / g) g: Content of carboxyl groups in the oxidized cellulose fiber (mmol / g)

[0114] 〔Contents of each component〕 The contents of each component other than water were calculated from the blending amounts of each component. Regarding the content of the glucose moiety, assuming that all of the anionic modified cellulose fiber and the modifying compound blended during the preparation of the modified cellulose fiber were ionically bonded, the mass of the anionic modified cellulose fiber contained in the blended modified cellulose fiber was regarded as the mass of the glucose moiety and calculated. Also, the water content in the dispersion or suspension was measured by Karl Fischer titration using CA-200 (manufactured by Mitsubishi Analytech Co., Ltd.). Also, the solid content concentration in various cellulose fibers was measured using an infrared moisture meter (manufactured by Shimadzu Corporation, MOC-120H) to measure the moisture concentration in the sample, and calculated from the difference from 100% by mass. The moisture concentration was measured every 30 seconds at a constant temperature of 150 °C for 1 g of the sample, and the value displayed when the mass decrease within 30 seconds became 0.1% or less was used.

[0115] 〔Confirmation of crystal structure in various cellulose fibers〕 The crystal structures of various celluloses such as cellulose raw materials, anionic modified cellulose fibers, and modified cellulose fibers were confirmed by measuring under the following conditions using a diffractometer (manufactured by Rigaku Corporation, MiniFlex II). Measurement pellet preparation conditions: By applying pressure to the target cellulose in the range of 10 - 20 MPa with a tablet press, a smooth pellet with an area of 320 mm 2 × thickness of 1 mm was prepared. X-ray diffraction analysis conditions: Step angle 0.01°, scan speed 10° / min, measurement range: diffraction angle 2θ = 5 - 40° X-ray source: Cu / Kα-radiation, tube voltage: 15kv, tube current: 30mA Peak splitting conditions: After removing background noise, a Gaussian function was fitted so that the error between 2θ = 13-23° was within 5%. The crystalline structures of various celluloses were confirmed by measuring them using the aforementioned diffractometer under the aforementioned conditions. The degree of crystallinity of the cellulose type I crystal structure was calculated using the area of ​​the X-ray diffraction peaks obtained by the aforementioned peak splitting, based on the following equation (A). Cellulose type I crystallinity (%) = [I cr / ( I cr +I am )] × 100 (A) [In the formula, I cr This is the area of ​​the diffraction peak at the lattice plane (002 plane) (diffraction angle 2θ = 22-23°) in X-ray diffraction, I am This indicates the area of ​​the diffraction peak in the amorphous region (diffraction angle 2θ = 18.5°).

[0116] [Anionic modified cellulose fiber] As the anionically modified cellulose fiber, TEMPO-oxidized cellulose fiber having the physical properties listed in Table 1 was used.

[0117] [Table 1]

[0118] Such anionically modified cellulose fibers can be prepared, for example, by the method described in the TEMPO oxidation treatment below.

[0119] In a 2L PP beaker equipped with a mechanical stirrer and stirring blades, weigh out 10g of bleached kraft pulp fiber from coniferous trees (as the raw material for natural cellulose fiber) and 990g of deionized water, and stir at 25°C and 100rpm for 30 minutes. Next, add 0.13g of TEMPO, 1.3g of sodium bromide, and 35.5g of 10.5% by mass sodium hypochlorite aqueous solution to 10g of pulp fiber in that order. Then, perform pH stat titration using an automatic titrator and add 0.5M sodium hydroxide aqueous solution dropwise to maintain the pH at 10.5. The reaction is carried out at 25°C for 120 minutes with a stirring speed of 100rpm.

[0120] Next, while stirring, 1M hydrochloric acid is added to adjust the pH of the suspension to 2. Then, the solids are filtered off by suction filtration. The process of dispersing the solids in deionized water and filtering them off by suction filtration is repeated until the conductivity of the filtrate is 200 μs / cm or less. The resulting solids are then dehydrated to obtain anionic modified cellulose fibers.

[0121] [Preparation of short-fiber anion-modified cellulose fibers 1] Anion-modified cellulose fiber 1 having the physical properties listed in Table 1 was subjected to a short-fiber treatment to obtain short-fiber anion-modified cellulose fiber 1 having the physical properties listed in Table 2. This short-fiber anion-modified cellulose fiber was designated as component (A). Specifically, a cake of anionically modified cellulose fiber 1 was taken, and deionized water was added until the solid content concentration was 5% by mass. The resulting mixture was stirred at 95°C under the time conditions shown in Table 2 to obtain an aqueous suspension of short-fiber anionically modified cellulose fibers. The obtained suspension was centrifuged using a high-speed refrigerated centrifuge (Koki Holdings Co., Ltd., CR21G III) at 25°C, 10,000 G, and for 1 minute to obtain short-fiber anionically modified cellulose fibers 1 having the physical properties shown in Table 2 as a precipitate. Furthermore, when this short-fiber anionic cellulose fiber 1 was subjected to a micronization process, its physical properties were as follows: average fiber diameter was 2.7 nm and average fiber length was 207 nm.

[0122] [Table 2]

[0123] Preparation Example 1 (Preparation of a composition containing cellulose fiber 1 having a modifying group and a resin) Shortened anionic cellulose fibers having the physical properties listed in Table 2 were added to 1-methoxy-2-propanol (PGME) to obtain a dispersion with a solid content of 0.5% by mass. 1.2 g of EO / PO amine was added to 300 g of the obtained dispersion and stirred at 25°C for 1 hour to obtain a dispersion of cellulose fibers having a modifying group. Here, the amount of EO / PO amine used as the modifying compound was 0.26 equivalents relative to the ionic group, i.e., carboxyl group, of the shortened anionic cellulose fibers. 600 g of epoxy resin was further added to the obtained dispersion of cellulose fibers having a modifying group and stirred at 25°C for 1 hour. The dispersion was then subjected to five treatments at 150 MPa using a high-pressure homogenizer (NanoVeta L-ES, manufactured by Yoshida Machinery Industry Co., Ltd.). Subsequently, PGME was distilled off from the dispersion of cellulose fibers having a modifying group using an evaporator to obtain a composition containing cellulose fibers 1 having a modifying group and resin. The obtained composition was liquid at room temperature.

[0124] Preparation Example 2 [Composition containing sodium-type cellulose fibers and resin] Short-fiber anionic modified cellulose fibers 1 having the physical properties listed in Table 2 were added to deionized water to obtain a dispersion with a solid content of 3.0% by mass. The obtained dispersion was adjusted to pH=10 with 0.5M sodium hydroxide, stirred at 25°C for 1 hour, and then subjected to dispersion treatment five times at 150 MPa using a high-pressure homogenizer (NanoVeta L-ES, manufactured by Yoshida Machinery Industry Co., Ltd.) to obtain a Na-type cellulose fiber dispersion. To 50 g of the obtained Na-type cellulose fiber dispersion, 300 g of PGME and 600 g of epoxy resin were added, stirred at 25°C for 1 hour, and then deionized water and PGME were removed from the Na-type cellulose fiber dispersion using an evaporator to obtain a composition containing Na-type cellulose fibers 1 and resin.

[0125] Example 1 (Composition containing modified cellulose fibers and resin) To 10 g of the composition obtained in Preparation Example 1 (containing 0.045 g of cellulose fiber 1 having a modifying group (the mass of the portion from which the modifying group is removed from the cellulose fiber having a modifying group is 0.025 g) and 9.955 g of resin), 0.5 g of curing agent and 0.3 g of curing accelerator were added, and the mixture was stirred at 25°C and 2000 rpm for 5 minutes using an automatic orbital stirrer (Sinky Co., Ltd., Awatori Rentaro), and degassed at 25°C and 2200 rpm for 2 minutes to obtain the compositions shown in Table 3.

[0126] Comparative Example 1 (Composition containing sodium-type cellulose fibers and resin) The composition of Comparative Example 1 was obtained by preparing the same method as in Example 1, except that the composition obtained in Preparation Example 1 was replaced with the composition obtained in Preparation Example 2.

[0127] Reference example 1 The composition of Reference Example 1 was obtained by preparing the material in the same manner as in Example 1, except that modified cellulose fibers were not used.

[0128] Test Example 1 (Evaluation by impregnation into fibers) [Preparation of carbon fiber reinforced resin] The compositions listed in Table 3 were applied to the body of screw tube No. 5 using a polypipette, and the body was then pressed against carbon fiber T700SC-12K-50C manufactured by Toray to impregnate the carbon fiber with the resin. Both ends of the resulting carbon fiber were secured with double clips (clip width (mm): 15, manufactured by Monotaro) to apply tension to the carbon fiber, and it was placed in a forced-air constant temperature incubator DKN402 (manufactured by Yamato Scientific Co., Ltd.). Carbon fiber reinforced resin was produced by heating at 130°C for 1 minute. No slack was observed in the tensioned carbon fiber, and the slack distance D of the carbon fiber relative to the distance S between the clips (D / S) was very close to 0.

[0129] [Evaluation of resin coating rate] The resin coating rate was calculated using the following formula. The results are summarized in Table 3. A higher resin coating rate indicates better suppression of dripping at high temperatures. a. Weigh the carbon fiber (tare weight) b. Weigh the carbon fibers impregnated with the resin composition (weight before heating). c. After heating the carbon fibers impregnated with the resin composition, measure their weight (weight after heating). Resin coating rate = (c. Weight after heating - a. Tare weight) / (b. Weight before heating - a. Tare weight)

[0130] The main components used in the above examples are detailed as follows: Resin: Epoxy resin (manufactured by Mitsubishi Chemical Corporation, jER828, epoxy equivalent = 184-194, weight-average molecular weight = 370) Hardener: Dicyandiamide (manufactured by Mitsubishi Chemical Corporation, DICY) was used, which was pulverized using a mini blender (manufactured by Osaka Chemical Co., Ltd.). Hardening accelerator: 3-(3,4-dichlorophenyl)-1,1-dimethylurea (DCMU) (manufactured by Thermo Scientific) was used, pulverized using a mini blender (manufactured by Osaka Chemical Co., Ltd.). PGME: 1-Methoxy-2-propanol (manufactured by Daicel Corporation) EO / PO amine: Methoxypoly(oxyethylene / oxypropylene)-2-propylamine (HUNTSMAN, Jeffermin M2070, Mw=2000, EO:PO=31:10)

[0131] [Table 3]

[0132] As shown in Table 3, Example 1, which contained modified cellulose fibers, had a high resin coating rate and effectively suppressed dripping. [Industrial applicability]

[0133] The resin composition of the present invention can be suitably used as a resin composition for impregnating fibers subjected to tensile stress. [Explanation of Symbols]

[0134] 1: Carbon fiber 2: Support (clip) S: Distance between supporting objects D: Sagging distance

Claims

1. A resin composition for impregnating fibers subjected to tensile stress, comprising the following components (A) and (B). Component (A): Modified cellulose fiber having modifying groups via ionic and / or covalent bonds to the anionic groups of anionic-modified cellulose fiber. Component (B): Non-aqueous liquid that is liquid at 25°C and 1 atm.

2. The resin composition according to claim 1, wherein the resin composition is a resin composition for impregnating fibers in a filament winding method or a continuous pultrusion method.

3. The resin composition according to claim 1, wherein the content of component (A) is 0.01 parts by mass or more and 10 parts by mass or less per 100 parts by mass of component (B).

4. The resin composition according to claim 1, wherein the modifying group of component (A) is a hydrocarbon group or a polymer group.

5. The resin composition according to claim 1, wherein component (B) is a curable resin.

6. The resin composition according to claim 1, further comprising a curing agent.

7. A method for producing a fiber-reinforced resin, comprising impregnating fibers subjected to tensile stress with a resin composition according to any one of claims 1 to 6.

8. A fiber-reinforced resin obtained by the manufacturing method described in claim 7.

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