Method for producing fibrous composite

Abstract

To provide a method for producing a fibrous composite that contains cellulose fibers and can be handled in a non-aqueous system, with a configuration different from conventional ones.SOLUTION: Provided is a method for producing a fibrous composite comprising a cyclization step and a denaturation step. The fibrous composite has a structure in which cellulose fibers and a copolymer are bonded through an ester bond. In the cyclization step, two adjacent carboxyl groups present in the copolymer are cyclized to form an anhydride carboxyl group, and in the denaturation step, the ester bond is formed by a hydroxy group present in a cellulose constituting the cellulose fibers and the anhydride carboxyl group present in the copolymer.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a method for producing a fibrous composite, and more particularly to a method for producing a fibrous composite using cellulosic fibers. [Background technology]

[0002] In recent years, cellulose fibers have been used in aqueous applications to control viscoelasticity, such as as a thickener. Meanwhile, in composite material applications, for example, cellulose fibers have been proven to be excellent reinforcing materials for resins for some time, but they have not yet been put to practical use. Thus, while cellulose fibers have been suggested to have excellent utility in composite material applications, they have not yet been put to practical use in many cases. One of the reasons for this is thought to be the strong hydrophilicity of cellulose fibers. Regarding this issue, the following patent documents 1 to 3 disclose known technologies. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2014-148629 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-176052 [Patent Document 3] Japanese Patent Application Publication No. 2019-189792 Summary of the Invention [Problem to be solved by the invention]

[0004] Cellulose fibers are generally handled in an aqueous dispersion, but increasing the solids concentration above 60% by mass can be difficult. This solids concentration decreases as the degree of defibration of the cellulose fibers in the aqueous dispersion increases, and in products generally referred to as nanocellulose, the solids concentration does not reach 15% by mass. In other words, cellulose is handled in a state where it coexists with far more water than the target components. This is thought to be because cellulose, a polysaccharide, has a high number of hydroxyl groups derived from sugar chains, making it highly hydrophilic. For example, as mentioned above, resin blending is difficult when there is more water than the target components. Even if blending is possible, removing the water requires a significant amount of energy. On the other hand, cellulose fibers have the property that, as the amount of water removed from an aqueous dispersion increases, the cellulose gradually aggregates and solidifies through hydrogen bonding. While this property is extremely useful in paper production, it is impossible to form a dispersion in the absence of water. Therefore, there are problems with cellulose fibers: they cannot be dispersed in a non-hydrophilic environment, and they cannot be dispersed in resins. Cellulose fibers must be handled in the presence of water, and they aggregate when the dispersant is removed. This makes them difficult to handle, and therefore there are many applications and uses for which their practical use is hindered.

[0005] In this regard, the above-mentioned Patent Document 1 discloses a technology (e.g., [Claim 1]) for chemically modifying some of the hydroxyl groups in the cellulose that constitutes the nanocellulose with alkanoyl groups having an alicyclic hydrocarbon group, with the aim of providing a novel modified nanocellulose and a resin composition containing the same (

[0011] ). The above-mentioned Patent Document 2 aims to provide a fiber-reinforced resin composition in which highly dispersible fibers are suitably combined, and a method for producing the same (

[0007] ). It discloses a fiber-reinforced resin composition ([Claim 1], etc.) that contains (A) chemically modified cellulose nanofibers and (B) a thermoplastic resin, in which the ratio R of the SP value of (A) to the SP value of (B) is 0.87 to 1.88, and the crystallinity of (A) is 42.7% or more. This disclosure mentions (

[0012] ) that the introduction of alkanoyl groups such as acetyl groups (i.e., chemically modifying the hydroxyl groups) blocks the hydroxyl groups of cellulose molecules, thereby suppressing the hydrogen bonding strength of the cellulose molecules. The above-mentioned Patent Document 3 discloses a modified cellulose nanofiber (e.g., [Claim 1]) that has a cellulose nanofiber, a polycarboxylic acid bonded to the cellulose molecules, and a polyvalent metal salt of a fatty acid having 8 to 24 carbon atoms that is chelate-bonded to carboxyl groups of the polycarboxylic acid other than the carboxyl group bonded to the cellulose molecule, with the aim of providing a modified cellulose nanofiber that can be kneaded with a thermoplastic resin in a dry powder state and has good compatibility and dispersibility in the thermoplastic resin (

[0009] ).

[0006] The techniques described in Patent Documents 1 to 3 all solve the above problems by chemically modifying hydroxy groups derived from sugar chains. These techniques make it possible to handle cellulose fibers in a non-aqueous system, thereby solving the problems associated with resin blending. However, for example, Patent Document 1 raises concerns about the need to use a special alicyclic compound as a chemical modifying agent, and Patent Document 2 raises concerns about the large amount of organic solvent used during production, requiring a total of 750 mL of organic solvent (Patent Document 1

[0445] ) for 5 g of plant fiber solids. Furthermore, the technology of Patent Document 3 uses a chelate bond via a metal salt, which is less stable than chemical modification using a covalent bond, and there are concerns about the long-term stability, hydrolysis resistance, and resistance to catalytic decomposition due to metal ions of products obtained using the modified cellulose. As such, although various methods are currently being investigated for chemical modification of cellulose, it remains unclear which technologies and solutions are appropriate and practical. In order to have more options for the future, more different options are needed.

[0007] The present invention has been made in consideration of the above-mentioned circumstances, and aims to provide a method for producing a fibrous composite that contains cellulosic fibers but can be handled in a non-aqueous system, using a configuration that is different from conventional methods. [Means for solving the problem]

[0008] That is, the present invention includes the following. [1] A method for producing a fibrous composite comprising a ring-closing step and a modification step, The fibrous composite has a structure in which cellulosic fibers and a copolymer are bonded by ester bonds, the ring-closing step is a step of forming a carboxy anhydride group by ring-closing two adjacent carboxy groups in the copolymer, A method for producing a fibrous composite, characterized in that the modification process is a process of forming the ester bond between a hydroxy group in the cellulose constituting the cellulosic fiber and the carboxyl anhydride group in the copolymer. [2] The method for producing a fibrous composite according to [1] above, wherein the ring closure is carried out by heating the copolymer having two adjacent carboxyl groups to a temperature of 50°C or higher and 300°C or lower. [3] The method for producing a fibrous composite according to [1] or [2], wherein the copolymer has an ethylene-propylene copolymer, an ethylene-butene copolymer, an ethylene-octene copolymer, or a styrene-ethylene / butylene-styrene copolymer as a backbone. [4] The fibrous composite according to [3] above, wherein the copolymer has structural units derived from at least two types of monomers differing in the number of carbon atoms by two or more. [5] The fibrous composite according to [1] or [2], wherein the copolymer has five or more carboxy anhydride groups. [Effects of the Invention]

[0009] According to the method for producing a fibrous composite of the present invention, a fibrous composite that contains cellulosic fibers and can be handled in a non-aqueous system can be obtained by a constitution different from that of the conventional method. DETAILED DESCRIPTION OF THE INVENTION

[0010] The matters set forth herein are for illustrative purposes only and are intended to provide an illustrative description of the embodiments of the present invention, with the aim of providing what is believed to be the most effective and easily understandable explanation of the principles and conceptual features of the present invention. In this respect, it is not intended to show structural details of the present invention beyond the extent necessary for a fundamental understanding of the present invention, and the description, taken together with the drawings, will make clear to those skilled in the art how some aspects of the present invention may be actually embodied. In this specification, unless otherwise specified, the expression "XX to YY" means "XX or higher and YY or lower." Furthermore, "normal temperature" means 25°C, and "normal pressure" means 1013.25 hPa.

[0011] The method for producing a fibrous composite of the present invention is a method for producing a fibrous composite including a ring-closing step and a modification step, The fibrous composite has a structure in which cellulosic fibers and a copolymer are bonded by ester bonds, the ring-closing step is a step of forming a carboxy anhydride group by ring-closing two adjacent carboxy groups in the copolymer, The modification step is characterized in that the ester bond is formed between a hydroxy group of the cellulose constituting the cellulosic fiber and the carboxy anhydride group of the copolymer.

[0012] The "fibrous composite" has a structure in which cellulosic fibers and a copolymer are ester-bonded. The term "cellulosic fiber" refers to a fibrous material primarily composed of cellulose. The maximum length of a cellulosic fiber is usually 1,000 μm or less, and can be 500 μm or less, 250 μm or less, or even 100 μm or less. The lower limit is not limited, and a single cellulose is usually 1 nm or more, 3 nm or more, 5 nm or more, or even 10 nm or more. These upper and lower limits can be appropriately combined. Therefore, for example, the maximum length can be 1 nm to 1,000 μm, 3 nm to 500 μm, 5 nm to 250 μm, or 10 nm to 100 μm.

[0013] Specific examples include plant-derived fibers, pulp, cellulose microfibrils, cellulose nanofibers (hereinafter also referred to simply as "CNF"), lignocellulose (fibrous lignocellulose), etc. These may be used alone or in combination of two or more. Therefore, for example, CNF (fiber width 3 to 100 nm, aspect ratio 10 or more, length 100 μm or less) according to ISO / TS 20477:2017 is included.

[0014] The origin of the cellulosic fiber is not limited, and examples thereof include cellulosic fiber obtained from plants, cellulosic fiber produced by microorganisms (bacterial cellulose), etc. These may be used alone or in combination of two or more. Of these, the cellulosic fibers obtained from plants may be those obtained primarily from plants, or they may be those re-obtained (secondarily obtained, or more multiple times obtained, etc.) from articles formed using the cellulosic fibers obtained primarily.

[0015] The primary source of acquisition is not limited to, but may be a tree, a plant, or other plants such as bamboo or algae. The tree may be any of tall trees, shrubs, subshrubs, conifers, broad-leaved trees, evergreen trees, deciduous trees, vines, etc. The part of the tree is not limited to, and may be, for example, xylem, roots, leaves, bark, etc. The plant may be annual, biennial, perennial, erect, creeping, vine, etc. The part of the plant is not limited to, and may be, for example, stems, roots, leaves, etc. These may be used alone or in combination of two or more. Examples of reclaimed materials include cloth, woven fabric, knitted fabric, paper, etc. These may be used alone or in combination of two or more.

[0016] The plant-derived fibers may be obtained by fiberizing plants in any manner, including, for example, plant-derived fibers obtained by pulping, plant-derived fibers obtained by retting, plant-derived fibers obtained by microbial decomposition, plant-derived fibers obtained by enzymatic decomposition, etc. These may be used alone or in combination of two or more.

[0017] Among the above, the plant-derived fibers (i.e., pulp) fiberized by pulping may be mechanically treated pulp (mechanical pulp (MP), groundwood pulp (GP), refiner ground pulp (RGP), thermomechanical pulp (TMP), etc.), chemically treated pulp (chemical pulp (CP), kraft pulp (KP), sulfite pulp (SP), soda pulp (AP), etc.), pulp treated to have properties of both of these (chemical ground pulp (CGP), semi-chemical pulp (SCP), etc.), or recycled pulp. Furthermore, it may be fiber pulp or dissolving pulp (DP). These may be used alone or in combination of two or more.

[0018] As mentioned above, the source of the pulp is not limited, and it may be wood pulp or non-wood pulp. Examples of wood pulp include softwood pulp (N pulp) and hardwood pulp (L pulp). These may be used alone or in combination of two or more. Examples of non-wood pulp include linter pulp, rag pulp, linen pulp, bagasse pulp, bamboo pulp, kenaf pulp, esparto pulp, hemp pulp, and straw pulp. These may be used alone or in combination of two or more.

[0019] Furthermore, there are no limitations on whether the pulp is bleached or not. Examples include bleached hardwood kraft pulp (LBKP), unbleached hardwood kraft pulp (LUKP), bleached softwood kraft pulp (NBKP), unbleached softwood kraft pulp (NUKP), bleached hardwood sulfite pulp (LBSP), unbleached hardwood sulfite pulp (LUSP), bleached softwood sulfite pulp (NBSP), unbleached softwood sulfite pulp (NUSP), etc. These may be used alone or in combination of two or more. Furthermore, there are no limitations on whether the pulp has been beaten. That is, it may be beaten pulp or unbeaten pulp. In the case of beaten pulp, it may be beaten pulp that has undergone a loose beating process or a sticky beating process. These may be used alone or in combination of two or more. In the case of beaten pulp, there are no limitations on the degree of beating and freeness (Canadian Freeness Standard [CFS]), etc.

[0020] Among the above, dissolving pulp (DP) can be selected from the viewpoints of odor reduction and heat resistance. Dissolving pulp has a high cellulose content, and therefore a lower content of lignin, which is thermally decomposed in a lower temperature heating environment, compared to non-dissolving pulp. Therefore, the use of dissolving pulp can reduce odor compared to when dissolving pulp is not used. Furthermore, better heat resistance can be obtained.

[0021] Here, the odor refers to an odor generated by the decomposition of components constituting cellulosic fibers. For example, in a molded body obtained from a resin for molding containing a fibrous composite, the resin for molding is heated (heated to a temperature at which the resin can flow) during molding, etc., which causes the decomposition of components constituting the cellulosic fibers, such as lignin. As a result, the resulting molded body may emit an odor. In contrast, when DP pulp is used as the cellulosic fiber, the amount of low-temperature decomposition components (such as lignin) contained in the DP pulp is small or substantially absent, so that no odor is generated even after the heating, or even if an odor is generated, the odor can be reduced.

[0022] Furthermore, excellent heat resistance can be exemplified by, for example, a reduced temperature dependence of mechanical strength. That is, as described above, in molded bodies obtained from resins for molded bodies containing a fibrous composite, lignin and the like are decomposed. As a result, the mechanical strength of the resulting molded body may be more temperature-dependent. Specifically, the rate at which the flexural modulus decreases with increasing temperature can be cited as an example. In contrast, when DP pulp is used as the cellulosic fiber, the amount of low-temperature decomposition components (lignin, etc.) contained in the DP pulp is small or substantially absent, so the rate at which the flexural modulus decreases even after the above-mentioned heating can be reduced compared to the former.

[0023] As mentioned above, cellulosic fibers are fibrous materials primarily composed of cellulose. However, the percentage of cellulose contained in the cellulosic fibers is not limited and can be, for example, 40% by mass or more, assuming that the entire cellulosic fiber is 100% by mass. When the cellulosic fibers contain 40% by mass or more of cellulose, the effects of cellulose can be effectively obtained. This percentage is preferably 50% by mass or more, and more preferably 60% by mass or more. This percentage may also be 100% by mass. The cellulose content in the cellulosic fibers is calculated from the alkali-decomposition-insoluble content. Specifically, the fibers are immersed in a 17.5% NaOH aqueous solution for two hours, followed by adding an equal volume of water to the NaOH aqueous solution and boiling for one hour. The dried residue (dried at 80°C or less) contained in the resulting liquid is used as the cellulose. If the measurement target contains lignin, the lignin is decomposed and removed by chlorine treatment, and then the cellulose content is measured. Specifically, the object to be measured is immersed in a solution of sodium chlorite and acetic acid mixed in a mass ratio of 5:1, heated to 80°C for 1 hour, and then filtered to obtain a residue, which is then subjected to the same procedure a total of four times to measure the amount of cellulose contained in the residue from which the lignin has been removed. However, since the number of cellulosic fibers constituting the fibrous composite and the cellulosic fiber powder (described later) produced during the manufacturing process thereof is large, and it is sufficient that the resulting fibrous composite and cellulosic fiber powder are formed, there is no practical meaning in specifying the cellulose content of each cellulosic fiber. Similarly, when using cellulosic fibers derived from plants, the cellulose content varies depending on the source (type, part, etc.), and depending on the degree of purification, some fibers have a high cellulose content and others have a low cellulose content, and these can be used in combination, so it is sufficient that the resulting fibrous composite and cellulosic fiber powder are formed, and there is no practical meaning in specifying the average value. Furthermore, as long as the fibrous composite and cellulosic fiber powder ultimately become fibrous composites and cellulosic fiber powders, they may or may not contain hemicellulose, lignin, and components derived therefrom.

[0024] Furthermore, the form of the cellulosic fiber is not limited other than being fibrous, but specifically, an aspect ratio of 4 or more is preferred. An aspect ratio of 4 or more makes it easier to maintain the fibrous form of the fibrous composite and the cellulosic fiber powder during the production process. The aspect ratio is more preferably 5 or more, and more preferably 6 or more. The aspect ratio is usually 10,000 or less. The aspect ratio can be determined by measuring the maximum and minimum lengths of the cellulosic fiber using an optical microscope or electron microscope and calculating the ratio between them. However, since the number of cellulosic fibers constituting the fibrous composite and the cellulosic fiber powder produced during the production process is large, and since it is sufficient for the resulting fibrous composite and cellulosic fiber powder to be formed, there is no practical meaning in specifying the aspect ratio of each cellulosic fiber. Similarly, when using plant-derived cellulosic fibers, the aspect ratio varies depending on the source (type, part, etc.), and depending on the processing process, some fibers have a large aspect ratio and some have a small aspect ratio, and these can be used in combination, so it is sufficient for the resulting fibrous composite and cellulosic fiber powder to be formed, and there is no practical meaning in specifying the average aspect ratio.

[0025] The "copolymer" is a component bonded to cellulosic fibers via ester bonds. In this specification, the copolymer will be described as follows, as needed. That is, among the copolymers before being bonded to cellulosic fibers, the copolymer before the ring-closing step is referred to as an "initial copolymer," and the copolymer after the ring-closing step is referred to as a "pre-copolymer." Furthermore, the copolymer after being bonded to cellulosic fibers is referred to as a "post-copolymer." Furthermore, when describing content common to these two, the term "copolymer" is also used.

[0026] The ester bond is formed between a hydroxy group contained in the cellulose constituting the cellulosic fiber and a carboxy anhydride group contained in the pre-copolymer. That is, some or all of the carboxy anhydride groups contained in the pre-copolymer are consumed in the formation of the ester bond. Therefore, the post-copolymer in the fibrous composite can have a carboxy group (a single carboxy group) that is the remainder of the carboxy anhydride groups consumed in the ester bond. That is, when a hydroxy group contained in cellulose and a carboxy anhydride group form an ester bond, only one of the two carboxy groups constituting the carboxy anhydride group participates in the ester bond, and the other carboxy group can remain as a carboxy group. The other carboxy group may exist without forming any bond, or it may form an ester bond with another hydroxy group contained in cellulose, for example, or it may form a bond other than the ester bond.

[0027] The carboxylic anhydride groups of the pre-copolymer may be entirely or partially consumed in the formation of ester bonds. If only a portion is consumed, the post-copolymer may have a carboxylic anhydride group and / or two adjacent carboxy groups (hereinafter also referred to as "dicarboxy groups") in addition to the ester bonds and a single carboxy group. A dicarboxy group is formed by ring-opening a carboxy anhydride group. That is, a carboxy anhydride group originally contains two carboxy groups, and a state in which the two carboxy groups are ring-closed can be said to form a carboxy anhydride group. On the other hand, a state in which the two carboxy groups are not ring-closed can be said to be a dicarboxy group. As such, a carboxy anhydride group and a dicarboxy group are reversible, and therefore, when expressing them collectively, they are also referred to as "acid-modified groups" below.

[0028] The pre-copolymer contains carboxyanhydride groups, which allow it to form ester bonds with the hydroxy groups of cellulose. In other words, the presence of carboxyanhydride groups as modifying groups allows for high reactivity. Therefore, ester bonds can be formed with the hydroxy groups of cellulose at relatively low temperatures. In other words, the copolymer can be modified with cellulose (cellulosic fiber). Furthermore, the small number of ester bonds allows the polymer compound (copolymer) to be modified with cellulose, which allows for extensive blocking of the hydroxy groups of cellulose and effectively inhibits the hydrophilicity of cellulose.

[0029] Although the pre-copolymer has carboxy anhydride groups after undergoing the ring closure step, there is no limitation as to whether the initial copolymer has carboxy anhydride groups or not. That is, the initial copolymer may have only dicarboxy groups, or may have both dicarboxy groups and carboxy anhydride groups.

[0030] The acid-modified group may be derived from any monomer or compound. For example, it can be introduced into the copolymer using a structure derived from maleic acid, itaconic acid, succinic acid, glutaric acid, adipic acid, citraconic acid, tetrahydrophthalic acid, butenylsuccinic acid, or an acid anhydride thereof (i.e., maleic anhydride, itaconic anhydride, succinic anhydride, glutaric anhydride, adipic acid anhydride, citraconic anhydride, tetrahydrophthalic anhydride, butenylsuccinic anhydride, etc.). These may be used alone or in combination of two or more. Among these, structures derived from maleic acid and / or maleic anhydride are preferred. Note that a carboxy anhydride group can form a dicarboxy group by hydrolysis. Similarly, a dicarboxy group can form a carboxy anhydride group by dehydration condensation.

[0031] In the fibrous composite of the present invention, a carboxyl group (-COOH), an epoxy group (-CO (a three-membered ring structure consisting of two carbon atoms and one oxygen atom)), an isocyanate group (-NCO), an oxazoline group (-CHNO), or the like can be used instead of the carboxyl group. However, the carboxyl group (-COOH) has a problem of lower reactivity than the carboxyl group. Furthermore, while epoxy groups, isocyanate groups, and oxazoline groups have excellent reactivity, they are deactivated when reacting with water in the reaction system (e.g., water coexisting with cellulose), and subsequently become unable to react with the hydroxy groups in cellulose. In this regard, even if a carboxyl group reacts with water in the reaction system to form a dicarboxy group, it can be dehydrated back into a carboxyl group in the system. Therefore, the carboxyl group and dicarboxy group can ultimately be deactivated by reacting with the hydroxy groups in cellulose. Therefore, cellulose can be modified more efficiently than by using reactive groups other than carboxyl group.

[0032] Furthermore, by using a copolymer chain as the main chain of the modifying component (copolymer) for cellulosic fibers, the main chain can be made bulkier than when a homopolymer chain is used as the main chain, and therefore the hydrophilicity of cellulose can be more effectively inhibited. In this specification, the term "copolymer" means that the main chain is a copolymer chain. Therefore, for example, modified polyethylene and modified polypropylene (modified PE, modified PP, etc.) are not included in the "copolymer" referred to in this application because their main chains are polyethylene and polypropylene, not copolymer chains. On the other hand, for example, modified ethylene propylene copolymers are included in the "copolymer" referred to in this application because their main chains are copolymer chains of ethylene and propylene. Similarly, for example, modified ethylene butene copolymers are included in the "copolymer" referred to in this application because their main chains are copolymer chains of ethylene and butene.

[0033] Furthermore, by using a copolymer chain as the main chain of the copolymer, the melting point of the copolymer can be kept lower than when a homopolymer chain is used as the main chain, and therefore cellulose can be modified at a lower temperature than when a homopolymer chain is used as the main chain. Furthermore, by using a copolymer chain as the main chain, it is possible to obtain greater flexibility in the main chain than when a homopolymer chain is used as the main chain. Therefore, compared to when a homopolymer chain is used as the main chain, there are more opportunities for the hydroxy groups of cellulose and the carboxy anhydride groups of the precopolymer to react. In other words, the reactivity between cellulose and the precopolymer can be improved. From the same perspective, it is preferable that the carboxy anhydride groups be contained in the side chains of the precopolymer rather than in the main chain of the precopolymer. In other words, it is preferable that the precopolymer has a side chain, and that the side chain contains a carboxy anhydride group.

[0034] Furthermore, using a copolymer chain as the main chain of the copolymer can provide greater elastomeric properties than using a homopolymer chain. Therefore, when a fibrous composite is used as an additive component, the cellulosic fiber can be prevented from becoming a fracture initiation point in the additive destination. For example, when unmodified cellulosic fiber (e.g., in a case where hydroxy groups derived from cellulose have been inhibited by other means) is added to an additive target (e.g., a resin), the additive target forms a matrix within which the unmodified cellulosic fiber is dispersed. In this case, the interface between the additive target and the unmodified cellulosic fiber is prone to dissociation due to the difference in their material properties, which can become a fracture initiation point. In contrast, in copolymer-modified cellulosic fiber (i.e., a fibrous composite), at least a portion of the cellulosic fiber is coated with the post-copolymer. This post-copolymer is present at the interface between the additive target and the cellulosic fiber, and furthermore, the elastic properties at this interface prevent the above-mentioned fracture initiation point from occurring. Therefore, by using a copolymer chain as the main chain of the copolymer, it is possible to prevent cellulosic fibers from becoming the starting point of breakage in the added destination.

[0035] The structure of the copolymer skeleton (the main chain obtained by excluding the side chains from the copolymer) is not limited, and various structures can be adopted. Specific examples include olefin copolymers, styrene copolymers, etc. These may be used alone or in combination of two or more. These may be used alone or in combination of two or more. Note that olefin copolymers include olefin elastomers (olefin thermoplastic elastomers). Similarly, styrene copolymers include styrene elastomers (styrene thermoplastic elastomers).

[0036] Examples of olefin copolymers include polymeric compounds obtained by copolymerizing two or more olefins as monomers. The copolymers may be random copolymers, block copolymers, copolymers of other types, hydrogenated copolymers thereof, or mixtures thereof.

[0037] Examples of the olefin include ethylene, propylene, and α-olefins having 4 to 8 carbon atoms. Examples of the α-olefins having 4 to 8 carbon atoms include butene (1-butene, etc.), pentene (3-methyl-1-butene, 1-pentene, etc.), hexene (3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, etc.), and octene (1-octene, etc.). These may be used alone or in combination of two or more.

[0038] Among these, the olefin copolymer is preferably a copolymer of ethylene and another α-olefin. That is, for example, a copolymer of ethylene and an α-olefin having 3 to 8 carbon atoms, or a copolymer of propylene and an α-olefin having 4 to 8 carbon atoms, etc. These may be used alone or in combination of two or more.

[0039] Among the above, examples of copolymers of ethylene and α-olefins having 3 to 8 carbon atoms include ethylene-propylene copolymer (EPR), ethylene-butene copolymer (EBR), ethylene-pentene copolymer, and ethylene-octene copolymer (EOR). Examples of copolymers of propylene and α-olefins having 4 to 8 carbon atoms include propylene-butene copolymer (PBR), propylene-pentene copolymer, and propylene-octene copolymer (POR). These may be used alone or in combination of two or more. Among these, copolymers of ethylene and an α-olefin having 3 to 8 carbon atoms are preferred. That is, EPR, EBR and EOR are preferred, and EBR and / or EOR are more preferred.

[0040] The styrene copolymer may be a polymer compound obtained by copolymerizing a styrene compound with another monomer, and may be a random copolymer, a block copolymer, a copolymer of another type, a hydrogenated product thereof, or a mixture thereof.

[0041] Examples of styrene-based compounds include styrene and its derivatives. These may be used alone or in combination of two or more. Among these, examples of styrene derivatives include alkylstyrenes such as α-methylstyrene, p-methylstyrene, and pt-butylstyrene, p-methoxystyrene, and vinylnaphthalene. These may be used alone or in combination of two or more.

[0042] Examples of monomers other than styrene-based compounds include conjugated diene compounds and olefins. Among these, examples of conjugated diene compounds include butadiene, isoprene, piperylene, methylpentadiene, phenylbutadiene, 3,4-dimethyl-1,3-hexadiene, and 4,5-diethyl-1,3-octadiene. These may be used alone or in combination of two or more. On the other hand, the olefins described above may be used.

[0043] Therefore, examples of styrene copolymers include styrene-butadiene-styrene copolymer (SBS), styrene-isoprene-styrene copolymer (SIS), styrene-ethylene / butylene-styrene copolymer (SEBS, i.e., hydrogenated SBS copolymer), and styrene-ethylene / propylene-styrene copolymer (SEPS). These may be used alone or in combination of two or more. Among these, SEBS is preferred.

[0044] As described above, various copolymer skeletons can be selected, but from the viewpoint of obtaining higher elastomeric properties, it is preferable to adopt a skeleton having structural units derived from at least two types of monomers differing in the number of carbon atoms by two or more. That is, for example, in the case of olefin-based copolymers, among EPR, EBR, EOR, PBR, POR, etc., EBR, EOR, and POR are preferred. Furthermore, in the case of styrene-based copolymers, any of the above-mentioned copolymers is also preferred. Furthermore, the copolymer skeleton is preferably linear rather than branched, from the viewpoints that it is easier to align with cellulose and that the crystallinity of the cellulose is less likely to be inhibited. By being linear, the hydrophilicity of cellulose can be inhibited more effectively.

[0045] The pre-copolymer may have one or more carboxy anhydride groups, and the number is not limited, but since the pre-copolymer is a polymer compound, having multiple carboxy anhydride groups rather than only one carboxy anhydride group will result in higher reactivity. Furthermore, when actually forming ester bonds with cellulosic fibers, having ester bonds at multiple locations is preferable to having only one ester bond, from the viewpoint of being able to more firmly modify the cellulose fibers with the copolymer.

[0046] As mentioned above, the number of carboxy anhydride groups in the pre-copolymer (the number of carboxy anhydride groups formed by dehydration of two adjacent carboxy groups) is not limited, but is preferably 2 or more, more preferably 3 or more, more preferably 4 or more, and even more preferably 5 or more. On the other hand, the number of carboxy anhydride groups does not need to be excessively large, and is usually 50 or less, preferably 30 or less, more preferably 20 or less, more preferably 12 or less, and can be 11 or less. These upper and lower limits can be appropriately combined. Therefore, for example, it can be 1 to 50, 2 to 30, 3 to 20, 4 to 12, or 5 to 11. The carboxylic anhydride group may be contained as a main part within the skeleton of the pre-copolymer (for example, a pre-copolymer obtained using maleic acid or maleic anhydride as a monomer), or may be contained in a grafted side chain to the skeleton of the pre-copolymer, or may be both.

[0047] The pre-copolymer may not have any functional groups other than the carboxy anhydride group, but may have other functional groups. In this case, the other functional groups include a carboxyl group (-COOH), an epoxy group (-CO (a three-membered ring structure consisting of two carbon atoms and one oxygen atom)), an oxazoline group (-CHNO), an isocyanate group (-NCO), etc. These may be used alone or in combination of two or more.

[0048] The molecular weight of the copolymer is not limited, but the weight-average molecular weight can be 30,000 or more, 50,000 or more, or even 70,000 or more. By increasing the weight-average molecular weight of the copolymer to 30,000 or more, the copolymer can be given sufficient bulk relative to the cellulosic fibers, thereby more effectively inhibiting the hydrophilicity of cellulose. On the other hand, the upper limit of the weight-average molecular weight is not limited, but is typically 1,000,000 or less, and can be 500,000 or less, 300,000 or less, or 200,000 or less. The weight-average molecular weight of the copolymer may exceed 1,000,000, but an excessively large molecular weight makes the copolymer itself difficult to handle, so it is preferably 1,000,000 or less. These upper and lower limits can be combined as appropriate. Therefore, for example, it can be 30,000 to 1,000,000, 30,000 to 500,000, 50,000 to 300,000, or 70,000 to 200,000. The mass average molecular weight is measured by the GPC method (standard polystyrene equivalent).

[0049] Although the properties of the copolymer are not limited, for example, the MFR (230°C / 2.16 kg) of the copolymer can be 10 g / 10 min or less. By ensuring that the MFR of the copolymer is 10 g / 10 min or less, higher elastomer properties can be obtained. This MFR can be further reduced to 7 g / 10 min or less, or even 5 g / 10 min or less. While the lower limit is not limited, it can be 0.5 g / 10 min or more, or even 1.0 g / 10 min or more. The MFR (230°C / 2.16 kg) of the copolymer is a value based on ISO 1133. The density of the precopolymer is 0.90 g / cm 3 or less, and further 0.89 g / cm 3 The lower limit of the density is not limited, but it can be 0.85 g / cm 3These MFR and density can be adjusted by the molecular weight and modification amount of the pre-copolymer. The density of the pre-copolymer is a value based on ISO1183.

[0050] The cellulosic fiber and the copolymer may be bonded at any ratio, but the copolymer can be bonded in a range of 0.001 to 500 parts by mass per 100 parts by mass of the cellulosic fiber. This range allows for the production of a fibrous composite containing cellulosic fiber that can be handled in a non-aqueous system. This ratio can be 0.005 parts by mass or more, 0.01 parts by mass or more, 0.5 parts by mass or more, 1 part by mass or more, 5 parts by mass or more, or 7 parts by mass or more. The upper limit is not limited, but can be 250 parts by mass or less, 150 parts by mass or less, 100 parts by mass or less, 80 parts by mass or less, or 50 parts by mass or less. These upper and lower limits can be combined as appropriate. Therefore, for example, it can be 0.005 to 250 parts by mass, 0.01 to 250 parts by mass, 0.5 to 150 parts by mass, 1 to 100 parts by mass, 5 to 80 parts by mass, or 7 to 50 parts by mass.

[0051] The "ring closure step" is a step in which two adjacent carboxy groups (dicarboxy groups) in the copolymer (initial copolymer) are ring-closed to form carboxy anhydride groups. In this case, all of the dicarboxy groups in the initial copolymer may be converted to carboxy anhydride groups, or only a portion of them may be converted. In other words, the ring closure step is a pretreatment step for increasing the proportion of carboxy anhydride groups in the initial copolymer. By including the ring closure step, the reactivity of the initial copolymer can be improved, thereby suppressing the deterioration and decomposition of the cellulosic fiber due to modification.

[0052] As mentioned above, the use of carboxy anhydride groups allows the copolymer to be modified onto cellulosic fibers at lower temperatures than when other functional groups are used. This suppresses the deterioration and decomposition of the cellulosic fibers during modification. However, carboxy anhydride groups typically react with water (HO) to open the ring and exist as dicarboxy groups. Functional groups in this dicarboxy group state are less reactive than functional groups in the carboxy anhydride state. Therefore, modifying cellulosic fibers with a pre-copolymer containing dicarboxy groups (to obtain ester bonds) requires a reaction temperature at or above the temperature at which the cellulosic fibers deteriorate and / or decompose.

[0053] In contrast, by dehydrating and ring-closing the dicarboxyl groups to form carboxyl anhydrides, high reactivity due to the presence of the carboxyl anhydrides can be achieved. That is, by increasing the proportion of carboxyl anhydrides present in the copolymer in advance, ester bonds can be obtained at a reaction temperature lower than the temperature at which the above-mentioned deterioration and / or decomposition occurs. Therefore, by ring-closing the carboxyl anhydrides as represented by [-CO-O-OC-] and utilizing them as literal carboxyl anhydrides, the above-mentioned deterioration and decomposition can be avoided, thereby modifying the copolymer with respect to the cellulosic fiber.

[0054] As mentioned above, the carboxy anhydride group is a group that can be written as [-CO-O-OC-] and has a cyclic acid anhydride skeleton formed by dehydrating one molecule of H2O from two adjacent carboxy groups. The carboxy anhydride group is also expressed as an acid anhydride group, a carboxylic acid anhydride group, a dicarboxylic acid anhydride group, etc. Whether the reactive group in the copolymer is a carboxy anhydride group or a dicarboxy group can be determined by infrared absorption spectroscopy. Specifically, when a carboxy anhydride group is present, a peak at 1790 cm due to the C=O of the carboxy anhydride group is detected. -1 and 1850cm -1 On the other hand, when a dicarboxy group is present, a peak due to C=O is observed at 1700-1720 cm-1 If both of these are present, all of the above peaks are allowed.

[0055] In the ring-closing step, it is sufficient that the amount of carboxy anhydride groups in the pre-copolymer after the ring-closing step is greater than that before the ring-closing step. This is because the reactivity can be improved by increasing the amount of carboxy anhydride groups in the pre-copolymer. Therefore, the amount of carboxy anhydride groups in the pre-copolymer after the ring-closing step is not limited, but using the above-mentioned infrared absorption spectrum as an index, it is preferable that the amount of carboxy anhydride groups in the pre-copolymer after the ring-closing step is greater than that before the ring-closing step. -1 The peak height (transmittance [%T], reflectance [%R], or absorbance [Abs]) is defined as H1, and the peak height is 1700 to 1720 cm -1 When the peak height (transmittance [%T], reflectance [%R], or absorbance [Abs]) of the above formula is H2, precopolymers in which H1 / H2 ≥ 0.5 are preferred, precopolymers in which H1 / H2 ≥ 0.8 are more preferred, and precopolymers in which H1 / H2 > 1 are even more preferred. By using such precopolymers, it is possible to suppress the deterioration and decomposition of cellulosic fibers during modification. The peak intensity of H2 may be substantially 0. Therefore, when the peak intensity of H2 is substantially 0, the upper limit of H1 / H2 is substantially infinite. That is, when the peak intensity of H2 is substantially 0, the upper limit of H1 / H2 is substantially infinite. That is, when the peak intensity of 1790 cm -1 There is a peak at 1700-1720 cm -1 The copolymer may be one in which the peak of

[0056] The peak intensity ratio of H1 to H2 may be adjusted by any method, for example, by heating. -1 Even if a copolymer does not have a peak at 1790 cm, heating at a temperature of 50°C or higher -1A peak of β-H1 / β-H2 can appear. That is, ring closure can be achieved by heating a copolymer having two adjacent carboxy groups to 50°C or higher. Furthermore, the value of H1 / H2 can be increased by increasing the heating temperature. Specifically, the heating temperature can be 80°C or higher, 110°C or higher, 140°C or higher, 160°C or higher, 165°C or higher, or 170°C or higher. The upper limit of the heating temperature is not limited, and may be any temperature at which the copolymer does not decompose or deteriorate. For example, the upper and lower limits can be set to 300°C or lower, 270°C or lower, or 235°C or lower. These upper and lower limits can be appropriately combined. Therefore, for example, the temperature can be 80 to 300°C, 110 to 270°C, 140 to 270°C, 160 to 235°C, or 165 to 235°C.

[0057] The "modification step" is a step of forming an ester bond between a hydroxy group in the cellulose constituting the cellulosic fiber and a carboxy anhydride group in the pre-copolymer. That is, a fibrous composite can be obtained by this modification. The modification step may be carried out in any manner, but is usually carried out by contacting the cellulosic fiber with a pre-copolymer (a copolymer having a carboxy anhydride group) and then applying reaction heat.

[0058] In order to increase the reaction rate, the contact between the cellulosic fiber and the pre-copolymer is preferably carried out at a temperature at which the pre-copolymer becomes flowable. This temperature may be achieved by external heating, by applying shear force by kneading, or by other methods. These may be used alone or in combination of two or more.

[0059] Any device may be used to bring the cellulosic fiber into contact with the precopolymer, including, for example, a mixer, kneader, extruder, kneader, or mixer (such as a high-speed fluid mixer, paddle mixer, or ribbon mixer). These may be used alone or in combination of two or more types. When two or more types are used, they may be operated continuously or batchwise (batchwise). Furthermore, the raw materials may be mixed all at once, or may be added and mixed in multiple batches (multi-stage blending). When these devices have a screw, they may be single-shaft, twin-shaft, or multi-shaft, with twin-shaft being preferred.

[0060] The above-mentioned modification conditions are not limited, and it is sufficient that the precopolymer is softened so that it can be mixed with the cellulosic fiber. However, as described above, from the viewpoint of suppressing decomposition and deterioration of the components constituting the cellulosic fiber (cellulose, lignin, hemicellulose, etc.), the mixing temperature can be set to 220°C or less, 210°C or less, 200°C or less, or 190°C or less. As described above, the lower limit of the mixing temperature is preferably selected depending on the type of precopolymer used, and can be, for example, 160°C or more, 165°C or more, 170°C or more, or 175°C or more. These upper and lower limits can be appropriately combined. Therefore, for example, the temperature can be set to 160 to 220°C, 165 to 210°C, 170 to 200°C, or 175 to 190°C.

[0061] As mentioned above, the cellulosic fibers used in the modification step may be in any state, but cellulosic fibers with a lower moisture content are preferred over those in a state where they coexist with water, and even more preferred are cellulosic fibers that are substantially free of moisture. Lowering the moisture content facilitates mixing of the cellulosic fibers with the pre-copolymer and increases the chance of reaction between the two, thereby improving the reactivity of the entire system. Additionally, the carboxy anhydride groups can be reacted effectively.

[0062] That is, cellulose fibers are originally aqueous cellulosic fibers that are maintained in a dispersed state by coexisting with water, and therefore must be handled in an aqueous system. On the other hand, copolymers are lipophilic (hydrophobic) materials and therefore must be handled in a non-aqueous system. Therefore, mixing aqueous cellulosic fibers and copolymers in the same system and reacting them is disadvantageous in terms of reaction efficiency. For this reason, it is preferable to modify the cellulosic fibers before the modification process so that they can be handled in a non-aqueous system. A powdering process can be used as a process for this modification. That is, the cellulosic fiber powder obtained in the powdering process is an aggregate of non-aqueous cellulosic fibers and is a material that can be handled in a non-aqueous system. This modification can be achieved by adding a water-soluble nonionic compound instead of the water interposed between the fibers of the aqueous cellulosic fibers. That is, a water-soluble nonionic compound is dissolved in water coexisting with aqueous cellulosic fibers to form a mixture containing dispersed aqueous cellulosic fibers, water, and the water-soluble nonionic compound, and then water is removed from this mixture to obtain a cellulosic fiber powder in which the water-soluble nonionic compound is interposed between the fibers of the cellulosic fibers.

[0063] The water-soluble nonionic compound is a nonionic compound that is soluble in water. That is, it is a compound that can be dissolved in water without ionization. Therefore, by removing water from the above-mentioned mixture, the water-soluble nonionic compound remains in the gaps between the cellulosic fibers, preventing the cellulosic fibers from aggregating. As a result, the cellulosic fibers do not agglomerate and remain separate. Furthermore, the cellulosic fiber powder can be obtained in powder form without chemically bonding (chemically reacting) the water-soluble nonionic compound to the cellulosic fibers or their constituents.

[0064] In other words, by utilizing an interpenetrating structure in which a water-soluble nonionic compound penetrates between aqueous cellulosic fibers, it is possible to obtain non-aqueous cellulosic fibers, i.e., cellulosic fiber powder, that can maintain a dispersed state without coexisting with water and without chemical bonding, using aqueous cellulosic fibers that cannot maintain a dispersed state unless coexisting with water as raw materials. As a result, while aqueous cellulosic fibers must be handled as a liquid or fluid, cellulosic fiber powder can be handled as a powder. Furthermore, while aqueous cellulosic fibers require the coexistence of a large amount of water, cellulosic fiber powder does not, which allows for a significant reduction in the mass of the cellulosic fibers when handling them. Furthermore, the elimination of water eliminates the need for refrigeration, allowing for storage at room temperature and normal pressure. Thus, the powdering process can significantly improve the handleability of cellulosic fibers.

[0065] As mentioned above, the water-soluble nonionic compound forms a cellulosic fiber powder without bonding with the cellulosic fiber (no IR shift due to chemical bonding is observed). This suggests that the cellulosic fiber and the water-soluble nonionic compound form an interpenetrating structure. This interpenetrating structure is further thought to be obtained by a coating structure in which the water-soluble nonionic compound covers the cellulosic fiber. This is derived from the fact that the cellulosic fiber powder exhibits excellent dispersibility in resin. In other words, the cellulosic fiber powder can obtain excellent dispersibility in resin by having an interpenetrating structure and a coating structure with the water-soluble nonionic compound.

[0066] Examples of such water-soluble nonionic compounds include pyrrolidone compounds, formamide compounds, acetamide compounds, alcohol compounds, sulfoxides, ketones, etc. These may be used alone or in combination of two or more. Examples of pyrrolidone compounds include 2-pyrrolidone and 2-pyrrolidone derivatives such as N-methyl-2-pyrrolidone, which may be used alone or in combination of two or more. Examples of formamide compounds include formamide and formamide derivatives such as N,N-dimethylformamide, etc. These may be used alone or in combination of two or more. Examples of acetamide compounds include acetamide, acetamide derivatives such as 2-chloroacetamide and N,N-dimethylacetamide, and polymers such as poly-N-vinylacetamide. These may be used alone or in combination of two or more. Examples of alcohol compounds include monohydric alcohols such as n-butanol, dihydric alcohols such as ethylene glycol, diethylene glycol, and propylene glycol, and polymers such as polyethylene glycol and polypropylene glycol. These may be used alone or in combination of two or more. Examples of sulfoxides include dimethyl sulfoxide, etc. These may be used alone or in combination of two or more. Examples of ketones include diethyl ketone, etc. These may be used alone or in combination of two or more.

[0067] The water-soluble nonionic compound may be solid at room temperature and normal pressure, but is preferably liquid. When the water-soluble nonionic compound is liquid at room temperature and normal pressure, it has better solubility and dispersibility in water coexisting with aqueous cellulosic fibers than when it is solid. That is, a small amount of the water-soluble nonionic compound can form the interpenetrating structure described above, and a small amount of the water-soluble nonionic compound can be used to powder the aqueous cellulosic fibers into cellulosic fiber powder. Among the above-mentioned water-soluble nonionic compounds, those that are solid at room temperature and normal pressure are acetamide, 2-chloroacetamide, poly-N-vinylacetamide, polyethylene glycol, and polypropylene glycol.

[0068] The water-soluble nonionic compound's water solubility (solubility in water) is not limited, but is preferably 0.05 g / 100 g H2O or more. That is, it is preferable that the water-soluble nonionic compound can be dissolved in an amount of 1 mass % or more in an aqueous dispersion of aqueous cellulosic fiber having a solids concentration of 5 mass %. A higher solubility is preferable from the viewpoint of dispersibility. That is, from the viewpoint of excellent dispersibility when dissolved in the aqueous dispersion, a higher solubility is preferable, and for example, it can be 0.5 g / 100 g H2O or more, 5 g / 100 g H2O or more, 50 g / 100 g H2O or more, or 100 g / 100 g H2O or more. On the other hand, the upper limit of the solubility in water is not limited and is substantially unlimited. That is, when the water-soluble nonionic compound is solid, it may have a solubility in twice the amount of water present, i.e., a solubility of 200 g / 100 g H2O, like acetamide, or when the water-soluble nonionic compound is liquid, it may have a solubility that allows it to be miscible with water, like N,N-dimethylacetamide.

[0069] Therefore, as mentioned above, from the viewpoint that higher solubility is preferable, among the water-soluble nonionic compounds exemplified above, liquids that are miscible with water are preferred. Therefore, 2-pyrrolidone, N-methyl-2-pyrrolidone, formamide, N,N-dimethylformamide, N,N-dimethylacetamide, dimethyl sulfoxide, ethylene glycol, diethylene glycol, and propylene glycol are preferred. These may be used alone or in combination of two or more. The solubility in water can be determined from values ​​recorded in various databases (such as MERCK INDEX (https: / / merckindex.rsc.org / )).

[0070] When the powdering process includes a mixture formation process (a process of forming a mixture of aqueous cellulosic fiber, water, and a water-soluble nonionic compound) and a water removal process (a process of evaporating and removing water from the mixture), the mixture formation process may be carried out before the water removal process, or may be carried out simultaneously with the water removal process, or may be both of these. The simultaneous execution of the mixture-forming step and the water-removing step refers to a case in which the formation of the mixture and the removal of water from the mixture proceed simultaneously. For example, a case in which components constituting the mixture are added during the water-removing step can be exemplified. That is, a case in which a water-soluble nonionic compound is added to a mixture of aqueous cellulosic fibers and water while simultaneously removing water. Another case in which water is added to a mixture of aqueous cellulosic fibers and water while simultaneously removing water can be exemplified. Examples of the latter include, when dry pulp is used as a raw material for aqueous cellulosic fibers, a process in which water is added to more reliably dissociate the cellulosic fibers, or a process in which water is added while beating to increase the degree of beating (a process to increase the degree of defibration). In this way, by improving the dissociation state of the cellulosic fibers, mutual penetration by the water-soluble nonionic compound can be more reliably achieved.

[0071] The mixture-forming step is a step of forming a mixture in which cellulosic fibers, a water-soluble nonionic compound, and water are present together. The method for forming the mixture is not limited as long as it can form a state in which cellulosic fiber, a water-soluble nonionic compound, and water coexist. For example, the mixture can be obtained by (1) mixing a coexistence of aqueous cellulosic fiber and water with a water-soluble nonionic compound. Alternatively, the mixture can be obtained by (2) mixing cellulosic fiber, water, and a water-soluble nonionic compound. Furthermore, the mixture can be obtained by (3) mixing cellulosic fiber with a mixture of a water-soluble nonionic compound and water. Furthermore, in the case of (1) above, the water-soluble nonionic compound can be added to the coexistence while mixing, or the mixture of a water-soluble nonionic compound and water can be added to the coexistence while mixing. These compounds may be used alone or in combination of two or more. When a mixture of aqueous cellulosic fiber and water is used to form the mixture, the ratio of aqueous cellulosic fiber to water in the mixture is not limited.

[0072] Any device may be used to form the mixture, including, for example, a mixer, kneader, extruder, kneader, mixer (high-speed fluid mixer, paddle mixer, ribbon mixer, etc.). These may be used alone or in combination of two or more. When two or more types are used, they may be operated continuously or batchwise (batchwise). Furthermore, the raw materials may be mixed all at once, or may be added and mixed in multiple batches (multi-stage blending). Furthermore, when these devices have a screw, they may be single-shaft, twin-shaft, or multi-shaft.

[0073] The proportion of each component in the mixture is not limited, but the mixture can be generally formulated so that the non-aqueous cellulosic fiber and the water-soluble nonionic compound are blended in the resulting cellulosic fiber powder. That is, the total of the cellulosic fiber and the water-soluble nonionic compound is taken as 100% by mass, and the proportion of the cellulosic fiber is R CThe proportion of water-soluble nonionic compounds is R W In terms of mass%, R C / R W >1 is preferable, and the lower limit thereof can be 1.1 or more, 1.3 or more, 1.5 or more, 2.0 or more, 3.0 or more, 5.0 or more, or 7.5 or more. On the other hand, this ratio (R C / R W The upper limit of R can be 10,000 or less, 1,000 or less, 500 or less, 100 or less, 50 or less, 25 or less, or 15 or less. These upper and lower limits can be appropriately combined. Therefore, for example, 1.0≦R C / R W ≦10000, and 1.1≦R C / R W ≦1000, and 1.1≦R C / R W ≦500, 1.5≦R C / R W ≦100, and 2.0≦R C / R W ≦50, 3.0≦R C / R W ≦25, 5.0≦R C / R W ≦15, and 7.5≦R C / R W It can be ≦15. However, for example, after removing water by evaporation, a step of removing the water-soluble nonionic compound can be provided so that the amount of the water-soluble nonionic compound is appropriate. When such a water-soluble nonionic compound removal step is provided, a large amount of the water-soluble nonionic compound can be blended regardless of the blending ratio.

[0074] The water removal step is a step of removing water from the mixture. Water may be removed by any method, and examples of the removal method include removal by evaporation (evaporative removal), removal by centrifugation (centrifugal removal), removal by compression (compressive removal), etc. These may be used alone or in combination of two or more. Among these, evaporation is preferred. When removing water by evaporation, by using a water-soluble nonionic compound having a boiling point higher than that of water, only water can be efficiently removed, and substantially the entire amount of the water-soluble nonionic compound blended in the mixture can be left in the resulting cellulosic fiber powder, thereby suppressing loss of the water-soluble nonionic compound.

[0075] The boiling point of the water-soluble nonionic compound is not limited, but when a water removal step by evaporation is performed, a water-soluble nonionic compound with a boiling point of over 100°C can be used. When the boiling point of the water-soluble nonionic compound is over 100°C, the difference in boiling points between water and the water-soluble nonionic compound can be utilized to remove water by evaporation from a mixture of aqueous cellulosic fiber, water, and the water-soluble nonionic compound to obtain cellulosic fiber powder.

[0076] In addition, from the viewpoint of facilitating separation from water during evaporation, the difference in boiling point from water can be made larger. That is, for example, the boiling point of the water-soluble nonionic compound is preferably 125°C or higher, preferably 150°C or higher, preferably 160°C or higher, preferably 170°C or higher, preferably 180°C or higher, and preferably 190°C or higher. On the other hand, although there is no upper limit to the boiling point of the water-soluble nonionic compound, when considering the case where the compound is blended into a resin as a modifier, it is preferable that the compound can be evaporated by heating during mixing (melting and kneading, etc.), thereby reducing the content inside the resulting product, etc. From this perspective, the boiling point of the water-soluble nonionic compound is preferably 280°C or lower, preferably 250°C or lower, preferably 230°C or lower, and preferably 210°C or lower. These upper and lower limits can be combined as appropriate. Therefore, the boiling point of the water-soluble nonionic compound can be, for example, 125 to 280°C, 125 to 250°C, 150 to 250°C, 150 to 210°C, or 160 to 230°C.

[0077] Within the above range, examples of water-soluble nonionic compounds having a boiling point in the range of 150 to 250°C include 2-pyrrolidone (boiling point 245°C), diethylene glycol (boiling point 244.3°C), formamide (boiling point 210°C), N-methyl-2-pyrrolidone (boiling point 202°C), ethylene glycol (boiling point 197.3°C), dimethyl sulfoxide (boiling point 189°C), propylene glycol (boiling point 188.2°C), N,N-dimethylacetamide (boiling point 165°C), and N,N-dimethylformamide (boiling point 153°C). Examples of water-soluble nonionic compounds having a boiling point in the range of 150 to 210°C include formamide (boiling point 210°C), N-methyl-2-pyrrolidone (boiling point 202°C), ethylene glycol (boiling point 197.3°C), dimethyl sulfoxide (boiling point 189°C), propylene glycol (boiling point 188.2°C), N,N-dimethylacetamide (boiling point 165°C), and N,N-dimethylformamide (boiling point 153°C). The boiling point values ​​can be obtained from the values ​​recorded in various databases (such as MERCK INDEX (https: / / merckindex.rsc.org / )).

[0078] When evaporation is used to remove water in the water removal step, the process may be carried out under any conditions, including atmospheric pressure, elevated pressure, reduced pressure, or a combination of these. Among these, evaporation under reduced pressure (evaporation under reduced pressure) is preferred from the viewpoint of energy costs, since it allows the heating temperature to be lowered. The reduced pressure conditions can be set within an appropriate range depending on the water-soluble nonionic compound used. The heating conditions can also be set within an appropriate range depending on the water-soluble nonionic compound used, and can be, for example, 90°C or higher, 100°C or higher, or 120°C or higher. The upper limit is not limited, but is usually 250°C or lower, or 200°C or lower. These upper and lower limits can be appropriately combined. Therefore, for example, the temperature can be 90 to 250°C, 100 to 200°C, or 120 to 200°C.

[0079] In the water removal step, the water may be removed partially or entirely from the mixture. That is, the water removal rate may be 100% or less. This is because the moisture content of the resulting cellulosic fiber powder may be 0%, but as long as it exists as a powder, the moisture content may be greater than 0%. Specifically, as described above, when the total mass of the resulting cellulosic fiber powder is taken as 100% by mass, the water content can be 25% by mass or less, 20% by mass or less, 15% by mass or less, 10% by mass or less, 5% by mass or less, or 1% by mass or less.

[0080] If necessary, a water-soluble nonionic compound removal step can be provided after the water removal step to remove the water-soluble nonionic compound. The removal of the water-soluble nonionic compound may be limited to a portion or all of the water-soluble nonionic compound contained in the resulting cellulosic fiber powder. The water-soluble nonionic compound may be removed by any means, but can be removed by evaporation, as in the case of water removal. In this case, after the water has been removed by evaporation, the water-soluble nonionic compound can be removed by evaporation continuously. Furthermore, when a water-soluble nonionic compound removal process is provided, the cellulosic fiber powder can contain a larger amount of water-soluble nonionic compound regardless of the blending ratio (content ratio) of the cellulosic fiber to the water-soluble nonionic compound described above.

[0081] The cellulosic fiber powder obtained in the powdering step may contain cellulosic fiber and a water-soluble nonionic compound, and the quantitative ratio thereof is not limited. However, the total of the cellulosic fiber and the water-soluble nonionic compound is taken as 100% by mass, and the proportion of the cellulosic fiber is taken as R C The proportion of water-soluble nonionic compounds is R W In terms of mass%, R C >R W That is, the ratio (R C / R W ) is R C / R W It is preferable that R is >1. C / R W By satisfying a value of >1, the amount of the water-soluble nonionic compound used can be reduced.

[0082] This ratio (R C / R W The lower limit of this ratio (R) can be 1.1 or more, 1.3 or more, 1.5 or more, 2.0 or more, 3.0 or more, 5.0 or more, or 7.5 or more. C / R W The upper limit of R can be 10,000 or less, 1,000 or less, 500 or less, 100 or less, 50 or less, 25 or less, or 15 or less. These upper and lower limits can be appropriately combined. Therefore, for example, 1.0≦R C / R W ≦10000, and 1.1≦R C / R W ≦1000, and 1.1≦R C / R W ≦500, 1.5≦R C / R W ≦100, and 2.0≦R C / R W ≦50, 3.0≦R C / R W ≦25, 5.0≦R C / R W ≦15, and 7.5≦R C / R W It can be ≦15.

[0083] The water content (moisture content) in the cellulosic fiber powder can be 0%, but the cellulosic fiber powder basically only needs to exist as a powder, and within this range, water may be contained, and the water content in the cellulosic fiber powder may be greater than 0%. In the cellulosic fiber powder, when the mass of the entire cellulosic fiber powder is taken as 100% by mass, the water content can be, for example, 25% by mass or less, 20% by mass or less, 15% by mass or less, 10% by mass or less, 5% by mass or less, or 1% by mass or less. Cellulose is inherently hydrophilic. Furthermore, the water-soluble nonionic compounds that inhibit the aggregation of cellulosic fibers in cellulosic fiber powder do not exert their effect by bonding with the hydroxyl groups of cellulose. Therefore, it is believed that the hydroxyl groups of cellulose exist in the same way as in aqueous cellulosic fibers. For this reason, it is believed that cellulosic fiber powder and its aggregate powder have hygroscopic properties. The moisture content can be measured using an infrared moisture meter under conditions of a drying temperature of 105°C and a drying time of 5 hours.

[0084] As explained above, this method can include steps such as a ring-closing step, a modification step, a powdering step, a mixture-forming step, and a water-removing step, but can also include other steps. Examples of other steps include a purification step for purifying cellulosic fibers. The purification step is a step for purifying cellulosic fibers, and can be, for example, a step for increasing the cellulose concentration or a step for increasing the degree of beating. The purification step is preferably carried out before the powdering step.

[0085] The applications of the fibrous composite obtained by this method are not limited, but can be used, for example, as a raw material for moldings, a modifier, a masterbatch, a carrier for additives, and the like. The raw material for the molded body is the main component constituting the molded body. That is, since the fibrous composite contains a post-copolymer, the fibrous composite itself can be molded into a molded body. Examples of molded bodies include injection molded bodies, extrusion molded bodies (sheet extrusion molded bodies, profile extrusion molded bodies, etc.), T-die molded bodies, blow molded bodies, injection blow molded bodies, inflation molded bodies, hollow molded bodies, vacuum molded bodies, foam molded bodies, compression molded bodies, press molded bodies, stamping molded bodies, transfer molded bodies, transfer molded bodies, and insert molded bodies.

[0086] Among the above, modifiers are components that can modify the properties of other materials when blended with them. Because fibrous composites contain cellulose fibers, they can be used as modifiers for fiber-reinforced resins, i.e., modifiers that improve the mechanical strength properties of molded articles obtained from the blended resin by blending them with a resin raw material for a molded article. Examples of mechanical strength properties include improved flexural modulus. Furthermore, examples of improved impact resistance include improving impact resistance to suppress the decrease in impact resistance that occurs as the flexural modulus increases. Furthermore, blending them with a resin raw material for a paint can modify the viscosity of the paint obtained from the blended resin for the paint. Examples of viscosity modifications include thickening, imparting or strengthening thixotropy, etc. Similarly, blending them with a resin raw material for an adhesive can modify the viscosity of the adhesive obtained by blending them. Examples of viscosity modifications include thickening, imparting or strengthening thixotropy, etc.

[0087] Furthermore, a masterbatch is similar to a modifier in that it is a component that can modify the properties of other materials when blended with them, but it differs from a modifier in that it already contains other materials. The carrier for additives is a carrier used when adding additives to other materials. The type of additive is not limited, but examples include flame retardants, flame retardant assistants, fillers, colorants, antibacterial agents, antistatic agents, etc. These may be used alone or in combination of two or more.

[0088] Among the above, the fibrous composite can be suitably used as a modifier, a carrier for an additive, etc. The type of the other material is not limited, and examples thereof include resins (thermoplastic resins, curable resins), thermoplastic elastomers, rubbers, etc. These may be used alone or in combination of two or more. Among these, the fibrous composite can be suitably used when the other material is a thermoplastic resin and / or a thermoplastic elastomer. Examples of such other materials include a thermoplastic polyolefin resin and / or a thermoplastic polyolefin elastomer.

[0089] The type of olefin constituting the above-mentioned thermoplastic polyolefin resin and thermoplastic polyolefin elastomer is not limited, and examples include ethylene, propylene, olefins having 4 carbon atoms (1-butene, etc.), olefins having 5 carbon atoms (3-methyl-1-butene, 1-pentene, etc.), olefins having 6 carbon atoms (3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, etc.), olefins having 8 carbon atoms (1-octene, etc.), etc. These may be used alone or in combination of two or more. Therefore, examples of polyolefins include polyethylene, polyethylene-based copolymers, polypropylene, polypropylene-based copolymers, polybutene, polybutene-based copolymers, etc. These polymers may be used alone or in combination of two or more. Furthermore, when two or more types are used, this includes both pellets made of mixed resins and pellet mixtures.

[0090] Among the above, polyethylene includes ethylene homopolymers and copolymers of ethylene and olefins having 3 or more carbon atoms. Examples of the latter include ethylene-propylene copolymers, ethylene-butene copolymers, ethylene-hexene copolymers, and ethylene-octene copolymers. Copolymers of ethylene and other olefins may be random copolymers or block copolymers. In addition, copolymers of propylene and other olefins contain ethylene-derived structural units in an amount of 50% or more of the total number of structural units.

[0091] In addition, as polyethylene, plant-derived polyethylene (hereinafter simply referred to as "plant-derived PE") with a bio-based carbon content of 80% or more according to ISO16620-2 can be used. This bio-based carbon content is the percentage of the total carbon content. 14 This is the plant-derived carbon content (bio-based carbon content) calculated based on the proportion of C. When using plant-derived PE, a bio-based carbon content of 80% or more (or 100%) is preferred, with plant-derived PE of 85% or more, or even 90% or more being acceptable. In addition to ISO 16620-2, values ​​measured in accordance with ASTM D6866 can also be used for the bio-based carbon content. Generally, the values ​​measured in accordance with these standards are essentially the same.

[0092] Plant-derived polyethylene is a polymer whose main backbone is a structure (methylene chain) of linked methylene groups (-CH2-). The methylene chain is a structural unit derived specifically from ethylene. Plant-derived PE also includes ethylene homopolymers and copolymers of ethylene and other olefins. These may be used alone or in combination of two or more. When the plant-derived PE is a copolymer, non-ethylene-derived units (units derived from other olefins) preferably account for 50% or less (more preferably 30% or less, and even more preferably 10% or less) of the total number of constituent units. This is because a lower proportion of non-ethylene-derived units allows for a higher bio-based carbon content. In other words, plant-derived PE that has a low proportion of non-ethylene-derived units (for example, 10% or less) and is essentially an ethylene homopolymer is preferred.

[0093] Examples of other olefins include olefins having 3 carbon atoms (propylene), olefins having 4 carbon atoms (1-butene, etc.), olefins having 5 carbon atoms (3-methyl-1-butene, 1-pentene, etc.), olefins having 6 carbon atoms (3-methyl-1-pentene, 4-methyl-1-pentene, 1-hexene, etc.), olefins having 8 carbon atoms (1-octene, etc.), etc. These may be used alone or in combination of two or more.

[0094] The properties of plant-derived PE are not limited, but include a density of 0.942 g / cm 3Preferably, the plant-derived PE is a high-density polyethylene of 35 g / 10 min or less. The MFR (230°C / 2.16 kg) of the plant-derived PE is preferably 35 g / 10 min or less, and can be 20 g / 10 min or less, or even 15 g / 10 min or less. While there are no lower limits, from the viewpoint of ease of melt-kneading, it is preferably 2 g / 10 min or more, and can be 3 g / 10 min or more. The MFR (230°C / 2.16 kg) of the plant-derived PE is a value measured in accordance with ISO 1133 or ASTM D1238. The values ​​according to these standards are usually substantially the same.

[0095] As mentioned above, the density of plant-derived PE is 0.942 g / cm 3 or more is preferable, and the density is 0.950 g / cm 3 The upper limit of the density is not limited, but it is 0.954 g / cm 3 The density of polyethylene is preferably a value measured in accordance with the standards of ISO 1183 or ASTM D792. The values ​​according to these standards are usually substantially the same. The compatibility of the above-mentioned MFR and density can be adjusted by adjusting the linearity, branching amount, molecular weight, etc. of the polyethylene.

[0096] Among the above, polypropylene includes propylene homopolymers and copolymers of propylene with other olefins. Examples of the latter include propylene-ethylene copolymers, propylene-butene copolymers, propylene-hexene copolymers, and propylene-octene copolymers. Furthermore, copolymers of propylene with other olefins may be random copolymers or block copolymers. Among these, propylene-ethylene copolymers can be used due to their excellent elastomeric properties. Propylene-ethylene copolymers are block copolymer polypropylenes with ethylene blocks as the dispersed phase. That is, they are polypropylene resins with a homopolypropylene continuous phase and a dispersed phase containing polyethylene within this continuous phase. Copolymer polypropylenes with ethylene blocks as the dispersed phase are also known as impact copolymers, polypropylene impact copolymers, heterophasic polypropylenes, and heterophasic block polypropylenes. Furthermore, copolymers of propylene with other olefins have more than 50% of their total structural units derived from propylene.

[0097] The properties of the polyolefin as another material are not limited. For example, in the case of polypropylene, the density is 0.85 to 0.95 g / cm. 3 (Furthermore, the density is 0.88 to 0.92 g / cm 3 ) can be used. The MFR (230°C / 2.16 kg) can be, for example, 15 g / 10 min or more. When the MFR of polypropylene is 15 g / 10 min or more (usually 100 g / 10 min or less), excellent impact resistance can be obtained. This MFR can further be 20 g / 10 min or more, or 25 g / 10 min or more. There is no upper limit, but from the viewpoint of ease of kneading, it can be 80 g / 10 min or less, or 50 g / 10 min or less. The MFR (230°C / 2.16 kg) of polyolefin is measured in accordance with ISO 1133. The compatibility of MFR and density can be adjusted by the linearity, branching amount, molecular weight, etc. of the polyolefin. [Example]

[0098] The present invention will be specifically described below with reference to examples. [1] Manufacturing of cellulosic fiber powder (1) Raw material components (1-1) Microfibrillated fiber (microfibrous cellulose), solid content concentration 14.4% by mass, product name "Cerish KY110N" (manufactured by Daicel Miraize Co., Ltd.) (1-2) Water-soluble nonionic compounds "NMP": N-methyl-2-pyrrolidone

[0099] (2)Equipment used We have prepared an apparatus with one reaction vessel capable of performing mixing, kneading, and vacuum distillation individually or simultaneously within the reaction vessel. The mixing and kneading operations of this apparatus include mixing the contents of the reaction vessel using a three-pronged stirrer (motor performance: 0.75 kW, 4P, 200 V, 60 Hz, 39 A, 1800 rpm / min) and heating the interior of the reaction vessel to a maximum of approximately 300°C using a heater jacket wrapped around the outer periphery of the reaction vessel. Furthermore, the apparatus is capable of performing distillation operations by reducing the pressure inside the reaction vessel to a maximum of approximately 0.1 MPa using a connected vacuum pump and heating the interior of the reaction vessel to a maximum of approximately 80°C using a heater jacket wrapped around the outer periphery of the reaction vessel.

[0100] (3) Powdering process Both raw materials were charged into a reaction vessel so that the solid content of the cellulosic fiber was 10 parts by mass when the water-soluble nonionic compound NMP was 1 part by mass. Then, the reaction vessel was decompressed to 0.072 MPa, and the stirrer was rotated at 20 Hz while the vessel was heated to a temperature of 120°C. Vaporization was performed under reduced pressure. After substantially all of the water contained in the charged raw materials had evaporated, the apparatus was stopped, and the reaction product was removed from the reaction vessel. The reaction product was a powdery product with a soft texture, i.e., a cellulosic fiber powder.

[0101] (4) Measurement of moisture content of cellulosic fiber powder The moisture content of the cellulosic fiber powder obtained in (3) above was measured using an infrared moisture meter (model "FD-720", manufactured by Kett Electric Laboratory Co., Ltd.) at a drying temperature of 105°C for 5 hours, and the moisture content was found to be 0% (rounded to the nearest whole number).

[0102] [2] Manufacturing of fiber composites (1)Copolymer (1-1) Copolymer 1 (mEPR) Maleic acid-modified ethylene-propylene copolymer (mEPR) / Copolymer backbone: Ethylene-propylene copolymer, Mass average molecular weight: 200,000, Type of carboxylic anhydride group: Derived from maleic anhydride, Number of acid-modified groups per molecule: 2.5

[0103] (1-2) Copolymer 2 (mEBR) Maleic acid-modified ethylene-butene copolymer (mEBR) / Copolymer backbone: ethylene-butene copolymer, mass average molecular weight: 100,000, type of carboxylic anhydride group: derived from maleic anhydride, number of acid-modified groups per molecule: 5

[0104] (1-3) Copolymer 3 (mEBR) Maleic acid-modified ethylene-butene copolymer (mEBR) / Copolymer backbone: Ethylene-butene copolymer, Mass average molecular weight: 100,000, Type of carboxylic anhydride group: Derived from maleic anhydride, Number of acid-modified groups per molecule: 10

[0105] (1-4) Copolymer 4 (mEOR) Maleic acid modified ethylene-octene copolymer (mEOR) / Copolymer backbone: Ethylene-octene copolymer, Type of carboxylic anhydride group: Derived from maleic anhydride

[0106] (1-5) Copolymer 5 (mSEBS) Maleic acid-modified hydrogenated styrene-butadiene copolymer (mSEBS) / Copolymer backbone: Hydrogenated styrene-butadiene copolymer, Type of carboxylic anhydride group: Derived from maleic anhydride, Number of acid-modified groups per molecule: 10

[0107] (2) Ring closure process Copolymers 1 to 5 shown in (1-1) to (1-5) above were each fed into a twin-screw kneading extruder (manufactured by Technovel Co., Ltd., model "KZW15TW-30 / 45MG-NH", screw diameter 15 mm, L / D=45), and kneaded under the conditions of a kneading temperature of 190°C, an extrusion rate of 0.6 kg / hour, and a screw rotation speed of 200 rpm, to subject each copolymer to a ring-closing treatment. Separately, copolymer 3 shown in (1-3) above was prepared without ring-closure treatment.

[0108] (3) Denaturation process Using the apparatus described in [1](2) above, the raw materials were charged into a reactor so that the cellulosic fiber powder was 1 part by mass, 5 parts by mass, 10 parts by mass, or 100 parts by mass of the copolymers 1 to 5 that had been subjected to ring-closure treatment in (2) above or the copolymer 3 that had not been subjected to ring-closure treatment was 1 part by mass, as shown in the "mass ratio of polymer to cellulosic fiber" in Table 1. Then, under reduced pressure of 0.030 MPa, the reactor was heated to 120°C while rotating the stirrer at 20 Hz, and a vacuum distillation operation was carried out. After substantially all of the water contained in the charged raw materials had been distilled, the reactor was stopped, and the reaction products (fibrous composites of Experimental Examples 1-1 to 1-8) were removed from the reactor. In all cases, the reaction products were powdery and soft to the touch.

[0109] (4) Measurement of moisture content of fibrous composite For the fibrous composites of Experimental Examples 1-1 to 1-8, the moisture content was measured using an infrared moisture meter (model "FD-720", manufactured by Kett Electric Laboratory Co., Ltd.) under conditions of a drying temperature of 105°C and a drying time of 5 hours, and the moisture content of all fibrous composites was 0% (rounded to the nearest integer).

[0110] [Table 1]

[0111] (5) Blending with polyolefin resins The fibrous composites of Experimental Examples 1-1 to 1-8 obtained in (4) above and a polyolefin resin (propylene block copolymer, manufactured by Japan Polypropylene, product name "Novatec BC6," MFR 2.7 g / 10 min, melting point 163°C) were each charged into a twin-screw extruder (manufactured by Technovel Co., Ltd., model "KZW15TW-30 / 45MG-NH," screw diameter 15 mm, L / D = 45), and mixed at a mixing temperature of 190°C, an extrusion rate of 0.6 kg / hr, and a screw rotation speed of 200 rpm to obtain thermoplastic resin compositions of Experimental Examples 2-1 to 2-8. Of these, the thermoplastic resin compositions of Experimental Examples 2-1 to 2-7 were slightly beige in color, and no burnt odor was detected from the resulting thermoplastic resin compositions. On the other hand, the thermoplastic resin composition of Experimental Example 2-8 was brown in color, and a burnt odor was detected from the resulting thermoplastic resin composition.

[0112] (6) Preparation of molded body for evaluation Each of the thermoplastic resin compositions obtained in Experimental Examples 2-1 to 2-8 was injection molded to produce molded articles for evaluation. As a result, molded articles were obtained from each of the thermoplastic resin compositions in Experimental Examples 2-1 to 2-7. On the other hand, the thermoplastic resin composition in Experimental Example 2-8 became brittle during molding, making molding difficult. The results are shown in Table 2 below.

[0113] [Table 2]

[0114] [3] Effects of the embodiment The fibrous composites of Experimental Examples 1-1 to 1-7 could all be blended with polyolefin-based resins as Experimental Examples 2-1 to 2-7. Furthermore, the dispersibility of the fibrous composites in the molded articles obtained from the thermoplastic resin compositions of Experimental Examples 2-1 to 2-7 was also good. On the other hand, the fibrous composite of Experimental Example 1-8 could be blended with polyolefin-based resins as Experimental Example 2-8, but a resin composition with sufficient moldability could not be obtained.

[0115] The present invention is not limited to the specific examples described above, and various modifications can be made within the scope of the present invention depending on the purpose and application.

[0116] The foregoing examples are for illustrative purposes only and are not to be construed as limiting the invention. While the invention has been described with reference to exemplary embodiments, it is understood that the language used in describing and illustrating the invention is descriptive and exemplary, rather than limiting. As detailed herein, changes may be made within the purview of the appended claims without departing from the scope or spirit of the invention in its form. While the description of the invention has referred to specific structures, materials, and examples, it is not intended that the invention be limited to the disclosure set forth herein; rather, the invention is intended to cover all functionally equivalent structures, methods, and uses within the scope of the appended claims.

Claims

1. A method for producing a fibrous composite, comprising a ring-closing step and a modification step, The fibrous composite has a structure in which cellulosic fibers and a copolymer are bonded by ester bonds, the ring-closing step is a step of forming a carboxy anhydride group by ring-closing two adjacent carboxy groups in the copolymer, A method for producing a fibrous composite, characterized in that the modification process is a process of forming the ester bond between a hydroxy group in the cellulose constituting the cellulosic fiber and the carboxyl anhydride group in the copolymer.

2. The method for producing a fibrous composite according to claim 1, wherein the ring closure is carried out by heating the copolymer having two adjacent carboxy groups at a temperature of 50°C or higher and 300°C or lower.

3. The method for producing a fibrous composite according to claim 1 or 2, wherein the copolymer has a skeleton of an ethylene-propylene copolymer, an ethylene-butene copolymer, an ethylene-octene copolymer, or a styrene-ethylene / butylene-styrene copolymer.

4. The method for producing a fibrous composite according to claim 3, wherein the copolymer has structural units derived from at least two types of monomers that differ in the number of carbon atoms by two or more.

5. The method for producing a fibrous composite according to claim 1 or 2, wherein the copolymer has five or more carboxy anhydride groups.

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