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 pulverization step and a denaturation step. The fibrous composite comprises cellulose fibers and a copolymer having an acid-modified group, the cellulose fibers being bonded to the copolymer, and the acid-modified group being an anhydrous carboxyl group and / or a carboxyl group derived from an anhydrous carboxyl group. The cellulose fibers and the copolymer are bonded through an ester bond formed between the acid-modified group and a hydroxy group present in a cellulose constituting the cellulose fibers. In the pulverization step, cellulose fiber powder is obtained by pulverizing the cellulose fibers by interposition of a water-soluble nonionic compound, and in the denaturation step, the cellulose fiber powder is mixed with the copolymer having the acid-modified group.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 carboxy groups of the polycarboxylic acid other than the carboxy 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 powdering step and a modification step, the fibrous composite is formed by bonding cellulosic fibers and a copolymer having an acid-modifiable group, the acid-modified group is a carboxy anhydride group and / or a carboxy group derived from a carboxy anhydride group, the cellulosic fiber and the copolymer are ester-bonded by a hydroxy group of cellulose constituting the cellulosic fiber and the acid-modified group, The powdering step is a step of obtaining a cellulosic fiber powder by powdering the cellulosic fibers with the aid of a water-soluble nonionic compound, A method for producing a fibrous composite, wherein the modification step is a step of mixing the cellulosic fiber powder with the copolymer having an acid-modifiable group. [2] The method for producing a fibrous composite according to [1] above, wherein the water-soluble nonionic compound has a boiling point of more than 100°C. [3] The cellulosic fiber powder has a ratio of the cellulosic fiber of R when the total of the cellulosic fiber and the water-soluble nonionic compound is 100% by mass. C % by mass, and the proportion of the water-soluble nonionic compound is R W When expressed as mass%, R C >RW The method for producing a fibrous composite according to the above [1] or [2], [4] A method for producing a fibrous composite according to any one of [1] to [3] above, wherein the water-soluble nonionic compound is at least one of N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide. [5] A method for producing a fibrous composite according to any one of [1] to [4] above, 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. [6] The method for producing a fibrous composite according to any one of [1] to [5] above, wherein the copolymer has five or more acid-modifiable 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 comprising a powdering step and a modifying step, the fibrous composite is formed by bonding cellulosic fibers and a copolymer having an acid-modifiable group, the acid-modified group is a carboxy anhydride group and / or a carboxy group derived from a carboxy anhydride group, the cellulosic fiber and the copolymer are ester-bonded by a hydroxy group of cellulose constituting the cellulosic fiber and the acid-modified group, The powdering step is a step of obtaining a cellulosic fiber powder by powdering the cellulosic fibers with the aid of a water-soluble nonionic compound, The modification step is characterized by mixing the cellulosic fiber powder with the copolymer having an acid-modifiable group.

[0012] The "fibrous composite" is formed by ester bonding between cellulosic fibers and a copolymer. The term "cellulosic fiber" as used herein refers to a fibrous material primarily composed of cellulose. In this specification, cellulosic fiber is referred to as follows, as necessary. That is, cellulosic fiber, which is a raw material for a fibrous composite and requires the coexistence of water to inhibit aggregation in the absence of a water-soluble nonionic compound or without being bound to a copolymer, is also referred to as "aqueous cellulosic fiber." Furthermore, cellulosic fiber that constitutes a cellulosic fiber powder and that no longer requires the coexistence of water due to the coexistence of a water-soluble nonionic compound, is also referred to as "non-aqueous cellulosic fiber." Furthermore, cellulosic fiber incorporated into a fibrous composite and ester-bonded to a copolymer is also referred to as "intra-composite cellulosic fiber." When referring to aqueous cellulosic fiber, non-aqueous cellulosic fiber, and intra-composite cellulosic fiber, the term "cellulosic fiber" is used.

[0013] The maximum length of such cellulosic fibers is usually 1000 μm or less, and can be 500 μm or less, 250 μm or less, or even 100 μm or less. There is no lower limit, 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 1000 μm, 3 nm to 500 μm, 5 nm to 250 μm, or 10 nm to 100 μm.

[0014] 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.

[0015] 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.

[0016] 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.

[0017] 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.

[0018] 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.

[0019] 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.

[0020] 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.

[0021] 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.

[0022] 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, heating (heating to a temperature at which the resin can flow) is performed during the manufacturing process of the fibrous composite, the molding process of the resin for molding, etc., resulting in 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 the DP pulp is substantially free of low-temperature decomposition components, so that no odor is generated even after the heating, or even if an odor is generated, the odor can be reduced.

[0023] 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.

[0024] As mentioned above, cellulosic fibers are fibrous materials primarily composed of cellulose. The percentage of cellulose contained in the cellulosic fibers is not limited, but 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 fiber is immersed in a 17.5% NaOH aqueous solution for 2 hours, followed by adding an equal volume of water to the NaOH aqueous solution and boiling for 1 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 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 plant-derived cellulosic fibers, 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.

[0025] 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.

[0026] The "copolymer" is a polymer having an acid-modified group and has constituent units derived from two or more types of monomers. The acid-modified group is a group that can function as an acid modified in the copolymer, and in the present invention, is at least one of a carboxy anhydride group and a carboxy group derived from a carboxy anhydride group. Of these, the former is a carboxy anhydride group having a closed ring structure. On the other hand, the latter is a carboxy group formed by ring-opening a carboxy anhydride group. Therefore, the latter forms a structure in which two carboxy groups are adjacent to each other (i.e., an open-ring structure). Hereinafter, the latter will also be referred to as a "dicarboxy group." As described above, the copolymer is ester-bonded to the cellulosic fiber in the fibrous composite. That is, the acid-modified group of the copolymer is ester-bonded to the hydroxy group of the cellulose. Therefore, since the acid-modified group of the copolymer is consumed by the ester bond in the fibrous composite, the fibrous composite usually has a structure in which the ester bond and the carboxy group, which is the remainder of the carboxy anhydride group, are present.

[0027] The copolymer contains acid-modified groups, which allow hydroxyl groups in cellulose to form ester bonds with the acid-modified groups. Specifically, by using carboxyl anhydride groups as acid-modified groups, high reactivity can be achieved within the copolymer, and high reactivity with the hydroxyl groups in cellulose can be obtained. Therefore, these groups can function as effective reaction sites within the polymer compound (copolymer), allowing the copolymer to be modified with respect to cellulose. Furthermore, the small number of ester bonds allows the polymer compound (copolymer) to be modified with respect to cellulose, thereby broadly inhibiting the hydroxyl groups in cellulose and effectively inhibiting the hydrophilicity of cellulose.

[0028] A carboxy anhydride group originally contains two carboxy groups, which form a ring-closed carboxy anhydride group. On the other hand, a dicarboxy group is composed of two adjacent carboxy groups and is not ring-closed. That is, both a carboxy anhydride group and a dicarboxy group contain two carboxy groups, but at least one of these two carboxy groups is ester-linked to a hydroxy group in cellulose. That is, when a hydroxy group in cellulose is ester-linked to a carboxy anhydride group, only one of the two carboxy groups in the carboxy anhydride group is ester-linked, while the other carboxy group can remain as a carboxy group. Similarly, when a hydroxy group in cellulose is ester-linked to a dicarboxy group, only one of the two carboxy groups in the dicarboxy group is ester-linked, while the other carboxy group can remain as a carboxy group. In either case, the remaining carboxy group may also be ester-linked to another hydroxy group in cellulose.

[0029] Furthermore, by using carboxy anhydride groups and / or dicarboxy groups as acid-modifying groups, copolymers can be modified into cellulosic fibers at relatively low temperatures. Therefore, the deterioration and decomposition of cellulosic fibers during modification can be suppressed. Specifically, these acid-modifying groups react with water (H2O) to open the ring and become dicarboxy groups. However, functional groups in the dicarboxy group state are less reactive than functional groups in the carboxy anhydride state, so a reaction temperature higher than the temperature at which the above-mentioned deterioration and decomposition occurs is required to obtain ester bonds. In contrast, high reactivity can be achieved by dehydrating and ring-closing the dicarboxy group to form a carboxy anhydride group. In other words, by increasing the probability of the presence of carboxy anhydride groups 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 decomposition occur. Therefore, by ring-closing the carboxy anhydride groups, as represented by [-CO-O-OC-], and actually using them as literal carboxy anhydride groups, the above-mentioned deterioration and decomposition can be avoided and copolymers can be modified to cellulosic fibers.

[0030] As mentioned above, a carboxy anhydride group can be written as [-CO-O-OC-], and is a group having a cyclic acid anhydride skeleton formed by dehydrating one molecule of H2O from two carboxy groups. A carboxy anhydride group can also be expressed as an acid anhydride group, a carboxylic acid anhydride group, a dicarboxylic acid anhydride group, etc. As mentioned above, unless a ring-closing treatment is performed, it usually exists as a dicarboxy group. 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 due to the C=O of the carboxy anhydride group is detected at 1790 cm -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 When both of these are present, all of the above peaks are observed. For the fibrous composite, the peak at 1790 cm is due to the carboxyl anhydride group. -1and the peak height of 1700–1720 cm due to the dicarboxyl group. -1 The peak height is equal to or equal to 1790 cm -1 A fibrous composite can be obtained by using a copolymer in which the peak height of

[0031] 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.

[0032] In addition, acid-modified groups are used as reactive groups in fibrous composites. However, instead of carboxy anhydride groups and dicarboxy groups, other groups such as carboxy groups (-COOH, nonadjacent carboxy groups), epoxy groups (-CO (a three-membered ring structure consisting of two carbon atoms and one oxygen atom)), isocyanate groups (-NCO), and oxazoline groups (-CHNO) can also be used. However, the carboxy group (-COOH) has a problem of lower reactivity compared to ring-closed carboxy anhydride groups. Furthermore, while epoxy groups, isocyanate groups, and oxazoline groups have excellent reactivity, they are deactivated when reacting with water in the system (e.g., water coexisting with cellulose), which subsequently makes them unable to react with the hydroxy groups in cellulose. In this regard, even if carboxy anhydride groups react with water in the reaction system to form dicarboxy groups, they can be dehydrated again in the system to return to carboxy anhydride groups. Therefore, carboxy anhydride groups and dicarboxy groups can ultimately be deactivated by reacting with the hydroxy groups in cellulose. Therefore, cellulose can be modified more efficiently than when other reactive groups other than the acid-modifiable group are used.

[0033] Furthermore, by using a copolymer as the main chain of the copolymer having an acid-modified group, the copolymer having an acid-modified group can be made bulkier than when a homopolymer is used, and therefore the hydrophilicity of cellulose can be more effectively inhibited. In this specification, a "copolymer having an acid-modified group" means that the main chain is a copolymer. Therefore, for example, modified polyethylene or modified polypropylene (maleic acid-modified PE or maleic acid-modified PP) has a main chain of polyethylene or polypropylene, and is not a copolymer, and therefore is not included in the "copolymer" referred to in this application. On the other hand, for example, a modified ethylene-propylene copolymer is included in the "copolymer" referred to in this application because its main chain is a copolymer of ethylene and propylene. Similarly, for example, a modified ethylene-butene copolymer is included in the "copolymer" referred to in this application because its main chain is a copolymer of ethylene and butene.

[0034] Furthermore, by using a copolymer as the main chain of the copolymer having an acid-modifiable group, the melting point of the copolymer can be kept lower than when a homopolymer is used as the main chain, and therefore the copolymer can be reacted with cellulose at a lower temperature than when a homopolymer is used as the main chain. Furthermore, by employing a copolymer as the main chain, it is possible to obtain greater flexibility in the main chain than when a homopolymer is employed as the main chain. Therefore, compared to when a homopolymer is employed as the main chain, there are more opportunities for the hydroxyl groups of cellulose to react with the acid-modified groups of the copolymer. That is, the reactivity between cellulose and the copolymer can be improved. From the same viewpoint, it is preferable that the copolymer has a side chain and that the acid-modified group is contained in the side chain, rather than that the acid-modified group be contained in the main chain of the copolymer.

[0035] Furthermore, by using a copolymer as the main chain of a copolymer having acid-modified groups, it is possible to obtain elastomeric properties compared to using a homopolymer. 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, and the unmodified cellulosic fiber is dispersed within the matrix. 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 copolymer, so the copolymer exists at the interface between the additive target and the cellulosic fiber. Furthermore, the copolymer exerts elastic properties at the interface, thereby preventing the above-mentioned fracture initiation point from occurring. Therefore, by using the copolymer as the main chain of the copolymer having an acid-modified group, it is possible to prevent cellulosic fibers from becoming the starting point of breakage in the added destination.

[0036] 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. Note that olefin copolymers include olefin elastomers (olefin thermoplastic elastomers). Similarly, styrene copolymers include styrene elastomers (styrene thermoplastic elastomers).

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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.

[0041] 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.

[0042] 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.

[0043] 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.

[0044] 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.

[0045] As described above, various options are available for the skeleton of the copolymer having an acid-modified group, 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 an olefin-based copolymer, among EPR, EBR, EOR, PBR, POR, etc., EBR, EOR, and POR are preferred. Furthermore, in the case of a styrene-based copolymer, any of the above-mentioned copolymers is also preferred. Furthermore, the skeleton of the copolymer having an acid-modifiable group 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.

[0046] The copolymer may have one or more acid-modified groups, and the number is not limited, but because the copolymer is a polymer compound, having multiple acid-modified groups will result in higher reactivity than having only one acid-modified group. 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.

[0047] As mentioned above, the number of acid-modified groups contained in the copolymer (in the present invention, when the acid-modified group is a carboxy anhydride group, this refers to the number of carboxy anhydride groups; when the acid-modified group is a dicarboxy group, this refers to the number calculated as one set of two carboxy groups constituting the dicarboxy group) is not limited, but is preferably 2 or more, more preferably 3 or more, more preferably 4 or more, and more preferably 5 or more. On the other hand, the number of acid-modified 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 acid-modified group may be contained in the main part within the copolymer backbone (for example, when maleic anhydride is used as a monomer), or may be contained in a grafted side chain to the copolymer backbone, or may be both.

[0048] The copolymer may not necessarily have any functional groups other than the acid-modified group, but may have other functional groups. In this case, examples of such 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), and an isocyanate group (-NCO). These may be used alone or in combination of two or more.

[0049] The molecular weight of the copolymer having an acid-modified group 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 making the weight-average molecular weight of the copolymer 30,000 or more, the copolymer can be given sufficient bulkiness relative to the cellulosic fiber, and the hydrophilicity of cellulose can be more effectively inhibited. On the other hand, the upper limit of the weight-average molecular weight is not limited, but is usually 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).

[0050] Although the properties of the copolymer having an acid-modified group are not limited, for example, the MFR (230°C / 2.16 kg) of the copolymer having an acid-modified group can be 10 g / 10 min or less. By having the copolymer have an MFR of 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 copolymer with acid-modified groups 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 copolymer. The density of the copolymer is a value based on ISO1183.

[0051] The cellulosic fiber and the copolymer having an acid-modified group may be bonded in any quantitative ratio, but the copolymer having an acid-modified group can be bonded in a range of 0.001 to 500 parts by mass per 100 parts by mass of the cellulosic fiber. Within this range, the modification of the copolymer having an acid-modified group allows the cellulosic fiber to be handled without coexistence with water. This quantitative 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.

[0052] The "powdering step" is a step in which cellulosic fibers are powdered with the aid of a water-soluble nonionic compound to obtain cellulosic fiber powder. That is, to form a fibrous composite containing cellulosic fibers, it is necessary to form an ester bond between the cellulosic fibers and the copolymer. However, as mentioned above, cellulose fibers are originally aqueous cellulosic fibers 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, it is difficult to mix and react aqueous cellulosic fibers and copolymers in the same system. For this reason, it is necessary to modify the cellulosic fibers so that they can be handled in a non-aqueous system before the modification process. 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 therefore 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, since the water-soluble nonionic compound can be dissolved in water coexisting with the aqueous cellulosic fiber, a mixture containing the aqueous cellulosic fiber, water, and the water-soluble nonionic compound dispersed therein can be formed. Then, by removing the water from this mixture, a cellulosic fiber powder can be obtained in which the water-soluble nonionic compound is interposed between the fibers of the cellulosic fiber.

[0053] 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 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 aggregate but remain separate, i.e., cellulosic fiber powder can be formed. 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.

[0054] 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.

[0055] 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.

[0056] 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.

[0057] 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.

[0058] 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.

[0059] 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 / )).

[0060] 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 (aqueous dispersion of aqueous cellulosic fibers) while simultaneously removing water can be exemplified. 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.

[0061] 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.

[0062] 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.

[0063] 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 C The 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.

[0064] 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.

[0065] 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.

[0066] 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.

[0067] 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 / )).

[0068] 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.

[0069] 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 than 100%. 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.

[0070] 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.

[0071] 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 WThat 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.

[0072] 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.

[0073] 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.

[0074] The "modification step" is a step of mixing a cellulosic fiber powder with a copolymer having an acid-modified group. This step allows a fibrous composite to be obtained. In other words, the modification step can also be referred to as a bonding step of bonding the cellulosic fiber with the copolymer having an acid-modified group. Furthermore, it can also be referred to as a bonding step of esterifying the hydroxyl group of the cellulose constituting the cellulosic fiber with the acid-modified group. As described above, the copolymer before being reacted with the cellulosic fiber powder has acid-modified groups (carboxy anhydride groups and / or carboxy groups derived from carboxy anhydride groups). The use of acid-modified groups can suppress the deterioration and decomposition of the cellulosic fibers during modification. The copolymer and fibrous composite are as described above.

[0075] The cellulosic fiber powder and the copolymer may be mixed in any manner as long as the cellulosic fiber and the copolymer can coexist in the same reaction system. In other words, the modification step can be further described as a step in which the cellulosic fiber powder and the copolymer having an acid-modifying group are coexisted in the same reaction system. Furthermore, in the modification step, the cellulosic fiber powder and the copolymer can be mixed in the same reaction system, and further, kneading can be performed. Furthermore, any apparatus can be used in the modification step. For example, a mixer, kneader, extruder, kneader, mixer (high-speed fluid mixer, paddle mixer, ribbon mixer, etc.), etc. can be used. These can be used alone or in combination of two or more. When two or more types are used, they can be operated continuously or batchwise (batchwise). Furthermore, the raw materials can be mixed all at once, or they can be added and mixed in multiple batches (multi-stage blending). Furthermore, when these apparatuses have screws, they can be single-shaft, twin-shaft, or multi-shaft, with twin-shaft being preferred.

[0076] The mixing conditions are not limited, and as described above, it is sufficient that the cellulosic fiber and the copolymer coexist in the same reaction system. Furthermore, it is preferable that the copolymer be softened so that it can be kneaded with the cellulosic fiber powder. When kneading, from the viewpoint of suppressing decomposition and deterioration of the components constituting the cellulosic fiber powder (cellulose, lignin, hemicellulose, etc.), the kneading temperature can be set to 220°C or less, 210°C or less, 200°C or less, or 190°C or less. The lower limit of the kneading temperature is preferably selected depending on the type of copolymer used, as described above, 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.

[0077] Furthermore, as mentioned above, depending on the environment, acid-modified groups are more likely to exist as dicarboxy groups than as carboxy anhydride groups. Therefore, it is preferable to use a copolymer in which the probability of the dicarboxy groups existing as carboxy anhydride groups has been increased by dehydrating and ring-closing the dicarboxy groups. That is, it is preferable to use a copolymer that has been ring-closed in the modification step. This is because using a copolymer with a high probability of the presence of carboxy anhydride groups can suppress the decomposition and deterioration of the components that make up the cellulosic fiber powder (cellulose, lignin, hemicellulose, etc.). That is, in this method, a copolymer that has been ring-closed in advance may be used in the modification step, or a ring-closure step in which the copolymer is ring-closed may be performed before the modification step.

[0078] The copolymer subjected to the ring closure treatment is not limited, but for example, in the infrared absorption spectrum, it has a peak at 1790 cm due to C=O of the carboxy anhydride group. -1 The peak height observed in the range of 1700 to 1720 cm is due to the C=O of the dicarboxy group. -1 Preferably, the copolymer has a peak height equal to or greater than that observed in the graph.

[0079] The ring-closure treatment may be carried out in any manner, but can be achieved by kneading the copolymer at high temperatures, regardless of whether the functional group is in the form of a carboxy anhydride group or a dicarboxy group. Specifically, a copolymer having a ring-closed carboxy anhydride group can be obtained by kneading at a temperature of 180°C or higher. The kneading temperature in the ring-closure treatment can be 185°C or higher, or 190°C or higher. The upper limit of the kneading temperature in the ring-closure treatment is not limited, but can be, for example, 220°C or lower, 210°C or lower, or 205°C or lower. These upper and lower limits can be appropriately combined. Therefore, for example, the temperature can be 185 to 220°C, 185 to 210°C, or 190 to 205°C.

[0080] As explained above, this method can include steps such as a powdering step, a modification step, a mixture formation step, a water removal step, and a ring-closing 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.

[0081] 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 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.

[0082] 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.

[0083] 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.

[0084] Among the above, the fibrous composite can be suitably used as a modifier, masterbatch, carrier for additives, 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.

[0085] 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.

[0086] 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.

[0087] 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.

[0088] 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.

[0089] 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.

[0090] 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.

[0091] 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.

[0092] 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.

[0093] 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]

[0094] The present invention will be specifically described below with reference to examples. [1] Manufacturing of cellulosic fiber powder (powdering process) (1)Each raw material component (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 "DMF": N,N-dimethylformamide "DMAc": N,N-dimethylacetamide "DMSO": dimethyl sulfoxide

[0095] (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.

[0096] (3) As shown in Table 1, NMP, DMF, DMAc, and DMSO were charged into a reaction vessel so that the solid content of the cellulosic fiber was 1 part by mass, 10 parts by mass, or 1,000 parts by mass, assuming 1 part by mass of each water-soluble nonionic compound. Then, with the pressure in the reaction vessel reduced to 0.072 MPa, the stirrer was rotated at 20 Hz, and the vessel was heated to a temperature of 120°C for vacuum evaporation. After substantially all of the water contained in the charged raw materials had evaporated, the apparatus was stopped, and the reaction products, i.e., cellulosic fiber powders of Experimental Examples 1 to 6, were removed from the reaction vessel. In all cases, these reaction products were powdery materials with a soft texture, i.e., cellulosic fiber powders.

[0097] (4) Measurement of moisture content of cellulosic fiber powder The moisture content of the cellulosic fiber powders of Experimental Examples 1 to 6 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 a drying time of 5 hours.The moisture content of all cellulosic fiber powders was found to be 0% (rounded to the nearest integer).

[0098] [Table 1]

[0099] [2] Manufacturing of fiber composites (modification process) (1) Cellulose fiber powder The cellulosic fiber powder obtained in Experimental Example 2 above [1] was used.

[0100] (2) Copolymers with acid-modified groups (2-1) 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

[0101] (2-2) 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

[0102] (2-3) 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

[0103] (2-4) Copolymer 4 (mEOR) Maleic acid modified ethylene-octene copolymer (mEOR) / Copolymer backbone: Ethylene-octene copolymer, Type of carboxylic anhydride group: Derived from maleic anhydride

[0104] (2-5) 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

[0105] (3) Ring-closing treatment Copolymers 1 to 5 shown in (2-1) to (2-5) above were each charged into a twin-screw kneading extruder and melt-kneaded at 190° C., and each of Copolymers 1 to 5 was subjected to a ring-closing treatment.

[0106] (4) Denaturation process Using the apparatus described in [1](2) above, both 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, per part by mass of the copolymer subjected to the ring-closure treatment described in (3) above, as shown in the "mass ratio of polymer to cellulosic fiber" in Table 2. 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 2-1 to 2-7) were removed from the reactor. In all cases, the reaction products were powdery and soft to the touch.

[0107] (5) Measurement of moisture content of fibrous composite For the fibrous composites of Experimental Examples 2-1 to 2-7, 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.The moisture content of all fibrous composites was 0% (rounded to the nearest integer).

[0108] [Table 2]

[0109] (6) Blending into thermoplastic resin compositions Each of the fibrous composites of Experimental Examples 2-1 to 2-7 obtained in (4) above was kneaded with a polyolefin resin (propylene block copolymer, manufactured by Japan Polypropylene, product name "Novatec BC6", MFR 2.7 g / 10 min, melting point 163°C) using a twin-screw kneading extruder to obtain each of the thermoplastic resin compositions of Experimental Examples 7-1 to 7-7.

[0110] [3] Effects of the embodiment The fibrous composites of Experimental Examples 2-1 to 2-7 could be blended with polyolefin resins in a wide range of blend ratios from 1:5 to 1:100 as Experimental Examples 7-1 to 7-7. Furthermore, the dispersibility of the fibrous composites in the thermoplastic resin compositions of Experimental Examples 7-1 to 7-7 was also good. This confirms that this method can produce fibrous composites that contain cellulosic fibers but can be handled in non-aqueous systems.

[0111] 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.

[0112] 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 powdering step and a modification step, the fibrous composite is formed by bonding cellulosic fibers and a copolymer having an acid-modifiable group, the acid-modified group is a carboxy anhydride group and / or a carboxy group derived from a carboxy anhydride group, the cellulosic fiber and the copolymer are ester-bonded by a hydroxy group of cellulose constituting the cellulosic fiber and the acid-modified group, The powdering step is a step of obtaining a cellulosic fiber powder by powdering the cellulosic fibers with the aid of a water-soluble nonionic compound, A method for producing a fibrous composite, wherein the modification step is a step of mixing the cellulosic fiber powder with the copolymer having an acid-modifiable group.

2. The method for producing a fibrous composite according to claim 1, wherein the water-soluble nonionic compound has a boiling point of more than 100°C.

3. The cellulose fiber powder has a ratio of the cellulose fiber of R when the total of the cellulose fiber and the water-soluble nonionic compound is 100 mass %. Ｃ % by mass, and the proportion of the water-soluble nonionic compound is R Ｗ When expressed as mass%, R Ｃ >R Ｗ The method for producing a fibrous composite according to claim 1, wherein

4. The method for producing a fibrous composite according to claim 2, wherein the water-soluble nonionic compound is at least one of N-methyl-2-pyrrolidone, N,N-dimethylformamide, N,N-dimethylacetamide, and dimethyl sulfoxide.

5. The method for producing a fibrous composite according to claim 1, 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.

6. The method for producing a fibrous composite according to claim 1 , wherein the copolymer has five or more acid-modifiable groups.

Images