Resin composition and method for producing same

Abstract

Provided are: a resin composition with which discoloration of a regenerated cellulose fiber caused by thermoforming can be suppressed and a molded article having excellent mechanical properties can be obtained; and a method for producing same.　The resin composition contains: a regenerated cellulose fiber (A) containing a fiber stabilizer (S) including a polyhydric alcohol; and a thermoplastic resin (B). Preferably, the fiber stabilizer (S) adheres to at least a portion of the surface of the regenerated cellulose fiber (A) and / or penetrates into at least a portion of the inside of the regenerated cellulose fiber (A).

Description

Resin composition and method for producing the same

[0001] The present disclosure relates to a resin composition and a method for producing the same.

[0002] Cellulose fibers are fibers containing cellulose, which is a major constituent of wood, and are classified into plant fibers, regenerated fibers (regenerated cellulose fibers), semi-synthetic fibers, cellulose nanofibers, and the like. Such cellulose fibers are not limited to applications such as clothing, and are widely applied as industrial raw materials for foods, cosmetics, functional papers, and the like.

[0003] Regenerated cellulose fibers can be produced by various methods such as the viscose method, the cuprammonium method, and the solvent method. In recent years, due to the increasing environmental awareness, regenerated cellulose fibers made from biomass-derived cellulose as a raw material have been adopted as a modifier or a reinforcing material for resins (for example, Patent Document 1 and the like).

[0004] When using regenerated cellulose fibers as a reinforcing material for a resin, a method of blending short fibers of regenerated cellulose into the resin to obtain a regenerated cellulose fiber reinforced resin composition, or impregnating a continuous fiber of regenerated cellulose with a resin and then cutting it into a desired length to obtain a resin material (resin-impregnated fiber bundle) reinforced with regenerated cellulose fibers is known. On the other hand, regenerated cellulose fibers have low thermal stability, and performance deterioration such as deformation and discoloration of the appearance due to heating, and reduction in the strength and elongation of the fibers occurs. Therefore, for example, in a resin composition containing regenerated cellulose fibers, when preparing the resin composition and / or heating to obtain a molded product of the resin composition, the regenerated cellulose fibers may be colored, resulting in poor appearance or a decrease in the mechanical properties of the resin.

[0005] JP-A-2017-95831 JP-A-2010-159364 JP-A-2008-163053

[0006] An object of the present disclosure is to provide a resin composition and a method for producing the same, which can suppress the coloring of regenerated cellulose fibers by heat molding and obtain a molded product having excellent mechanical properties.

[0007] As a result of diligent research by the inventors of the present invention, they have found that the above problem can be solved with a resin composition comprising regenerated cellulose fibers containing a polyhydric alcohol as a fiber stabilizer and a thermoplastic resin. That is, the present disclosure includes the following embodiments: [1] A resin composition comprising regenerated cellulose fibers (A) containing a fiber stabilizer (S) containing a polyhydric alcohol and a thermoplastic resin (B).

[0008] According to this disclosure, it is possible to provide a resin composition and a method for producing the same that can suppress the discoloration of regenerated cellulose fibers by heat molding and produce molded articles with excellent mechanical properties.

[0009] This table compares the coloring levels of the regenerated cellulose fibers from Example 1 and Comparative Examples 1-2.

[0010] One embodiment of this disclosure will be described in detail below, but the scope of this disclosure is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of this disclosure. Each embodiment disclosed herein can be combined with any other features disclosed herein. Furthermore, if multiple upper and lower limits are given for a particular parameter, any upper and lower limit can be combined to form a suitable numerical range. Also, the lower and / or upper limits of the numerical range described herein may be replaced with numerical values ​​within that range, as shown in the examples. The expression "X to Y" indicating a numerical range means "X or more and Y or less". If a particular description given for one embodiment also applies to other embodiments, that description may be omitted in the other embodiments. Each configuration and combination thereof in each embodiment is an example, and additions, omissions, substitutions, and other modifications can be made as appropriate without departing from the spirit of this disclosure. This disclosure is not limited by embodiments. Each aspect disclosed herein can be combined with any other features disclosed herein.

[0011] [Resin Composition] The first embodiment of this disclosure relates to a resin composition. The resin composition according to the first embodiment comprises regenerated cellulose fibers (A) containing a fiber stabilizer (S) containing a polyhydric alcohol, and a thermoplastic resin (B). According to the resin composition according to the first embodiment, discoloration of the regenerated cellulose fibers by heat molding can be suppressed, and a molded product with excellent mechanical properties can be obtained.

[0012] <Regenerated Cellulose Fiber (A)> The resin composition according to the first embodiment includes regenerated cellulose fiber (A) containing a polyhydric alcohol fiber stabilizer (S). By including the polyhydric alcohol fiber stabilizer (S) in the regenerated cellulose fiber (A) (hereinafter sometimes simply referred to as "fiber (A)"), discoloration of the fiber (A) is suppressed by heating during the preparation of the resin composition and during the molding of the resin composition. In this specification, regenerated cellulose fiber that does not contain the fiber stabilizer (S) is referred to as "raw material regenerated cellulose fiber (or raw material fiber)".

[0013] In one embodiment, fiber (A) may be a continuous fiber, a short fiber, or a spun fiber made by twisting short fibers together to form a long thread. In one embodiment, fiber (A) may be nanocellulose.

[0014] In one embodiment, the average fiber length of the regenerated cellulose fibers (A) in the resin composition is preferably 3 to 100 mm, more preferably 3 to 50 mm, and even more preferably 4 to 10 mm. Including regenerated cellulose fibers (A) having such an average fiber length makes it easier to improve the mechanical strength of the molded product. The average fiber length of the fibers (A) in the resin composition can be calculated as the average value of the monofilament fiber lengths measured by dissolving and removing the resin of the resin composition with an organic solvent (such as xylene), dispersing the fibers (A) in a medium, and then image processing the fibers (A). Alternatively, if the resin composition is a resin-impregnated fiber bundle (X) described later, the length of the long axis of approximately 100 pellets of the resin-impregnated fiber bundle (X) can be measured with a caliper or the like, and the average value can be used to calculate the average fiber length.

[0015] When fiber (A) is a short fiber, the average fiber length of the short fibers in the resin composition may be 0.1 to 10 mm, 0.1 to 5 mm, 0.1 to 3 mm, or 1 mm or more but less than 3 mm. The average fiber length of the short fibers can be calculated by the method of removing the resin with the organic solvent described above. When fiber (A) is nanocellulose, the average fiber length of the nanocellulose blended into the resin composition may be in the range of several hundred nm to several μm.

[0016] The average fiber diameter of fiber (A) is not particularly limited, and an appropriate range of average fiber diameters can be adopted depending on the physical properties required of the resin composition. In one embodiment, the average fiber diameter of fiber (A) may be 5 to 50 μm or 7 to 30 μm. The average fiber diameter of fiber (A) can be determined by the average value of the major axis of the fiber cross-section measured with a microscope.

[0017] If fiber (A) is a short fiber, the average fiber diameter of the short fiber may be 5 to 50 μm, or 7 to 30 μm. The average fiber diameter of the short fiber can also be measured using the microscope method described above. If fiber (A) is nanocellulose, the average fiber diameter of the nanocellulose may be 10 nm to 1 μm.

[0018] <Fiber Stabilizer (S)> The regenerated cellulose fiber (A) contains a fiber stabilizer (S) containing a polyhydric alcohol. "Fiber stabilizer" refers to an agent that has the function of maintaining and / or improving the thermal stability of the regenerated cellulose fiber within the thermoplastic resin (B). In one embodiment, the above function may include the function of changing the crystal structure of cellulose within the thermoplastic resin (B). Furthermore, the function of changing the crystal structure may change the crystal structure of cellulose in at least the surface portion of the fiber from type II to type IV. ＩＩ It may include a function to change the type.

[0019] Examples of polyhydric alcohols that can be incorporated into the fiber (A) as a fiber stabilizer (S) include polyhydric alcohols having 2 to 20 carbon atoms. Specifically, examples include chain-like polyhydric alcohols such as mannitol, glycerin, erythritol, pentaerythritol, xylitol, glucitol, and ethylene glycol. These may be used individually or in combination of two or more. Of these, from the viewpoint of easily suppressing discoloration of the fiber (A) during resin composition preparation and heat molding, it is preferable to include glycerin, mannitol, erythritol, or ethylene glycol, more preferably glycerin, mannitol, or erythritol, and particularly preferable to include glycerin.

[0020] In one embodiment, the ratio of fiber stabilizer (S) to 100 parts by mass of regenerated cellulose fiber (A) is preferably 0.1 to 20 parts by mass, more preferably 0.3 to 15 parts by mass, and even more preferably 0.5 to 15 parts by mass. The above ratios are expressed in parts by mass as the ratio of fiber stabilizer (S) when the total amount of regenerated cellulose fiber (A) is 100 parts by mass. If the ratio of fiber stabilizer (S) is within the above range, the regenerated cellulose fiber (A) is less likely to be discolored by heating during the preparation of the resin composition and during the molding of the resin composition. In one preferred embodiment, the fiber stabilizer (S) may contain 0.01 to 20 parts by mass, 0.03 to 15 parts by mass, or 0.05 to 10 parts by mass of glycerin per 100 parts by mass of regenerated cellulose fiber (A).

[0021] In one embodiment, the fiber stabilizer (S) may contain components other than polyhydric alcohols. In one particularly preferred embodiment, from the viewpoint of easily suppressing discoloration of the fibers during heat molding of the resin composition, the fiber stabilizer (S) contains only polyhydric alcohols.

[0022] In the resin composition according to the first embodiment, it is preferable that the fiber stabilizer (S) containing a polyhydric alcohol is attached to at least a portion of the surface of the fiber (A) and / or penetrates at least a portion of the interior of the fiber (A). In this case, a portion of the polyhydric alcohol may be reacted with the reducing ends of the cellulose constituting the fiber (A). For example, if the polyhydric alcohol contains glycerin, it may include one or more states selected from a state in which glycerin has reacted with the reducing ends of the cellulose of the fiber (A), a state in which glycerin is attached to at least a portion of the surface of the fiber (A), and a state in which glycerin has penetrated at least a portion of the fiber (A).

[0023] As described above, the resin composition according to the first embodiment includes fibers (A) containing a fiber stabilizer (S) containing a polyhydric alcohol. In such a resin composition according to the first embodiment, the exact reason why discoloration of the fibers (A) due to heat molding can be suppressed and molded products with excellent mechanical properties can be obtained is unknown, but it is thought that (1) due to the heat load during the preparation of the resin composition and during molding, the polyhydric alcohol blended as a fiber stabilizer (S) reacts with the reducing ends of the cellulose, improving the thermal stability of the fibers (A), and (2) due to the above heat load, the crystalline structure of the cellulose in a part of the fibers (A) (preferably including the surface of the fibers (A)) changes, improving the thermal stability of the fibers (A). In the resin composition according to the first embodiment, it is presumed that both (1) and (2) above occur in the thermoplastic resin (B). The crystalline structure of the cellulose in the fibers (A) can be evaluated by X-ray diffraction or the like.

[0024] Conventionally, methods for improving the thermal stability of cellulose by adding weak acids such as boric acid to cellulose fine powder or cellulose filter paper are known (for example, Patent Documents 2-3, etc.). However, these methods have only considered improving the thermal stability of cellulose alone, and have not considered improving the thermal stability of regenerated cellulose fibers within a resin composition when they are incorporated into the resin composition. The inventors of the present invention have found that by combining fibers (A) containing a polyhydric alcohol-containing fiber stabilizer (S) with a thermoplastic resin (B), the phenomena described in (1) and / or (2) above occur in the thermoplastic resin (B), making it easier to suppress discoloration of the fibers due to thermal load during molding of the resin composition, and furthermore, obtaining molded products with excellent mechanical properties. In order to obtain such effects, it is important to incorporate a polyhydric alcohol-containing fiber stabilizer (S) into the regenerated cellulose fibers, and it has been found that when boric acid, which is known as a cellulose fiber stabilizer, is incorporated into the regenerated cellulose fibers, discoloration of the fibers may progress due to heating during molding, such as at high processing temperatures, and that mechanical properties may be lower than when boric acid is not added (untreated product). In other words, the inventors of this application have found that by incorporating polyhydric alcohol as a fiber stabilizer into regenerated cellulose, discoloration of the fibers within the molded product is suppressed more effectively than when boric acid is incorporated, and the mechanical properties of the molded product are also more easily improved.

[0025] The proportion of regenerated cellulose fibers (A) in the resin composition can be arbitrarily set according to the form of the fibers (A) and the physical properties required for the resin composition. In one embodiment, when the fibers (A) are short fibers, the proportion of fibers (A) to the total mass of the resin composition may be 1 to 50% by mass or 5 to 40% by mass.

[0026] If the regenerated cellulose fiber (A) is nanocellulose, the proportion of fiber (A) in the resin composition may be 0.5 to 40% by mass.

[0027] <Thermoplastic Resin (B)> The resin composition according to the first embodiment includes a thermoplastic resin (B). The thermoplastic resin (B) included in the resin composition according to the first embodiment is not particularly limited as long as it, when combined with the regenerated cellulose fiber (A), produces the effects described in this disclosure. In a preferred embodiment, from the viewpoint of easily obtaining a molded article with good mechanical properties and easily suppressing discoloration of the fiber (A), the composition includes one or more thermoplastic resins selected from the group consisting of a crystalline resin (b1) with a melting point of 250°C or less and an amorphous resin (b2) with a glass transition temperature of 150°C or less. Preferred examples of the crystalline resin (b1) with a melting point of 250°C or less and the amorphous resin (b2) with a glass transition temperature of 150°C or less will be described below.

[0028] (Crystalline resin (b1)) The crystalline resin (b1) (hereinafter sometimes referred to as "resin (b1)") having a melting point of 250°C or less is not particularly limited, but examples include polyolefin resins, vinyl alcohol resins, vinyl ester resins, polyester resins, polyamide resins, polyacetal resins, etc. Also, examples of resin (b1) include thermoplastic elastomers, biodegradable resins, biomass resins, etc. The melting point of resin (b1) is a value obtained by DSC measurement (DSC measurement is performed under conditions of heating rate: 20°C / min and cooling rate: 10°C / min, and the melting peak temperature of the 2nd scan is taken as the melting point).

[0029] Examples of polyolefin resins include homopolymers or copolymers of olefins having 2 to 6 carbon atoms [ethylene resins such as high-density polyethylene (HDPE), low-density polyethylene (LDPE), low-density linear polyethylene (LLDPE), and ethylene-propylene copolymers; propylene resins such as polypropylene and propylene-butene copolymers; butene resins such as poly-1-butene and polyisobutylene; poly(methylpentene-1); propylene-methylpentene copolymer; ethylene-propylene-diene ternary copolymer (with a diene component as a raw material of 10% by mass or less); polymethylpentene, etc.]; copolymers of olefins having 2 to 6 carbon atoms and copolymerizable monomers [ethylene or poly Examples include copolymers of polypropylene (50 mol% or more) with vinyl acetate, alkyl (meth)acrylate, and / or aromatic vinyl compounds (random, block, and / or graft copolymers); and homopolymers or copolymers of cyclic olefins (especially cyclic olefins condensed with hydrocarbon rings, bridged ring cyclic olefins, etc.) which may have substituents such as alkyl groups or ester groups (for example, homopolymers of cyclic olefins such as polybicyclopentadiene and polynorbornene; copolymers of cyclic olefins selected from bicycloalkadienes, tricycloalkadienes, bicycloalkenes, and tricycloalkenes with α-olefins having 2 to 4 carbon atoms (ethylene, etc.)). These may be used individually or in combination of two or more. When a polypropylene resin is included, the polypropylene resin may include an acid-modified polypropylene resin (preferably a maleic anhydride-modified polypropylene resin and / or a maleic acid-modified polypropylene resin).

[0030] Examples of vinyl alcohol-based resins include polyvinyl alcohol and ethylene-vinyl alcohol copolymers. These may be used individually or in combination of two or more.

[0031] Examples of vinyl ester resins (carboxylate vinyl ester resins) include polyvinyl acetate and ethylene-vinyl acetate copolymers. These may be used individually or in combination of two or more.

[0032] Examples of polyester resins include homopolyesters or copolyesters (such as those using repeating alkylene terephthalates (ethylene terephthalate, butylene terephthalate, etc.) or alkylene naphthalates (ethylene naphthalate, butylene naphthalate, etc.) as repeating units (copolyesters using aliphatic dicarboxylic acids with 6 to 12 carbon atoms such as adipic acid, asymmetric aromatic dicarboxylic acids such as phthalic acid and isophthalic acid, and alkylene glycols, polyoxyalkylene glycols, bisphenol A, etc., with 2 to 6 carbon atoms as copolymer components); liquid crystalline polyesters with a melting point of 250°C or lower; and lactones (such as ε-caprolactone), either alone or as copolymers. These may be used individually or in combination of two or more.

[0033] Examples of polyamide resins include aliphatic polyamides (nylon 6, nylon 610, nylon 612, nylon 11, nylon 12, etc.); aromatic polyamides with a melting point of 250°C or less [polyamides obtained by the reaction of aromatic dicarboxylic acids (terephthalic acid, etc.) with aliphatic diamines (hexamethylenediamine, etc.); polyamides obtained by the reaction of aliphatic dicarboxylic acids (adipic acid, etc.) with aromatic diamines (metaxylylenediamine, paraxylylenediamine, etc.)]; and lactams (ε-caprolactam, etc.), either alone or copolymers thereof. These may be used individually or in combination of two or more. Furthermore, the polyamide resin is not limited to homopolyamides but may also be copolyamides.

[0034] Examples of polyacetal resins include polyacetal (polyoxymethylene) and copolymers (trioxane-ethylene oxide copolymer, trioxane-1,3-dioxolane copolymer, etc.). These may be used individually or in combination of two or more.

[0035] Examples of thermoplastic elastomers include polyolefin-based thermoplastic elastomers, polybutadiene-based thermoplastic elastomers, polyester-based thermoplastic elastomers, and polyamide-based thermoplastic elastomers. These may be used individually or in combination of two or more types.

[0036] Examples of biodegradable resins include one or more selected from cellulose esters, starch polyesters, polylactic acid (PLA), poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH), polylactic acid / polycaprolactone copolymers, polyglycolic acid (PGA), polylactic acid / polyether copolymers, butanediol / long-chain dicarboxylic acid copolymers, polybutylene adipate / terephthalate (PBAT), polytetramethylene adipate-coterephthalate, polyethylene terephthalate succinate (PETS), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), and polyvinyl alcohol (PVA).

[0037] Biomass resins are made from bio-derived materials, either partially or entirely, and include bio-PP, bio-PE, bio-polyamide 11, bio-polyamide 1010, aromatic polyesters containing bio-derived resins, bio-polyurethanes, bio-polycarbonates, bio-MXD 10, 1012, 610, 510, 410, 56, 11T, bio-PET, bio-PTT, and the like. These may be used individually or in combination of two or more types.

[0038] As the resin (b1), one of the above-mentioned thermoplastic resins may be used alone, or two or more may be used in combination.

[0039] (Amorphous resin (b2)) Amorphous resin (b2) (hereinafter sometimes referred to as "resin (b2)") having a glass transition temperature of 150°C or less is not particularly limited, but examples include vinyl chloride resins, styrene resins, (meth)acrylic resins, etc. Resin (a2) also includes thermoplastic elastomers, biodegradable resins, biomass resins, etc. The glass transition temperature of resin (a2) is a value measured in accordance with JIS K 7121 (measurement conditions: heating rate: 20°C / min, and the glass transition temperature at the midpoint of the 1st scan is taken as the glass transition temperature).

[0040] Examples of vinyl chloride resins include polyvinyl chloride and vinyl chloride-vinyl acetate copolymers. These may be used individually or in combination of two or more types.

[0041] Examples of the styrene resin include polystyrene, styrene-α-methylstyrene copolymer, styrene-(meth)acrylate copolymer, styrene-maleic anhydride copolymer, and the like. These may be used alone or in combination of two or more.

[0042] Examples of the (meth)acrylic resin include poly(meth)acrylate such as poly(meth)acrylate methyl, methyl methacrylate-(meth)acrylic acid copolymer, methyl methacrylate-(meth)acrylate copolymer, methyl methacrylate-(meth)acrylate-(meth)acrylic acid copolymer, (meth)acrylate-styrene copolymer (MS resin, etc.), and the like. These may be used alone or in combination of two or more.

[0043] Examples of the amorphous thermoplastic elastomer, biodegradable resin, and biomass resin having a glass transition temperature of 150°C or lower include cellulose ester resins such as cellulose acetate resin, and the like. These may be used alone or in combination of two or more.

[0044] As the resin (b2), one of the above-mentioned thermoplastic resins may be used alone, or two or more thereof may be used in combination.

[0045] In one embodiment, the thermoplastic resin (B) preferably contains the resin (b1), and preferably contains one or more resins (b1) selected from polyolefin resins, polyamide resins, and polyacetal resins.

[0046] In a preferred embodiment, the polyolefin resin preferably includes at least one selected from homopolymers or copolymers of olefins having 2 to 6 carbon atoms, and copolymers of olefins having 2 to 6 carbon atoms and copolymerizable monomers. More specifically, for example, polypropylene, high-density polyethylene (HDPE), low-density polyethylene (LDPE), low-density linear polyethylene (LLDPE), poly-1-butene, polyisobutylene, copolymers of ethylene and propylene, ethylene-propylene-diene terpolymers (where the diene component as a raw material is 10% by mass or less), polymethylpentene, random, block, and / or graft copolymers of ethylene or propylene (50 mol% or more) and other copolymer monomers (such as vinyl acetate, (meth)acrylic acid alkyl esters, aromatic vinyl compounds, etc.) can be mentioned. It is preferable to use these polyolefin resins alone or in combination of two or more. Among these, from the viewpoints of mechanical strength and processability, it is particularly preferable to include polypropylene.

[0047] In one embodiment, when the thermoplastic resin (B) includes a polyolefin resin, it is preferable to use an acid-modified polyolefin in combination from the viewpoint of easily improving the impregnability of the thermoplastic resin (B) into the regenerated cellulose fiber (A). As the acid-modified polyolefin, maleic acid-modified polyolefin (preferably maleic acid-modified polypropylene) and maleic anhydride-modified polyolefin (preferably maleic anhydride-modified polypropylene) are more preferable. Also, in one embodiment, when using a polyolefin resin and an acid-modified polyolefin in combination as the thermoplastic resin (B), it is more preferable to use the acid-modified polyolefin so that the acid amount (the amount of the acid component contained in the acid-modified polyolefin) in the thermoplastic resin (B) is in the range of 0.05 to 0.5% by mass on average in terms of maleic anhydride.

[0048] (Resin-impregnated fiber bundle (X)) The resin composition according to the first embodiment preferably includes a resin-impregnated fiber bundle (X) (hereinafter referred to as "fiber bundle (X)"), which is obtained by impregnating a fiber bundle (A1) made by bundling regenerated cellulose fibers (A) aligned in the length direction with the thermoplastic resin (B). The fiber bundle (X) is a composite material obtained by impregnating a fiber bundle (A1) made by bundling regenerated cellulose fibers (A) aligned in the length direction with the thermoplastic resin (B) and then cutting it. In one embodiment, the resin composition may contain the fiber bundle (X) and any thermoplastic resin, or it may contain only the fiber bundle (X).

[0049] The average fiber length of the regenerated cellulose fibers (A) in the fiber bundle (X) can be the same as the average fiber length of the regenerated cellulose fibers (A) in the aforementioned resin composition. That is, the average fiber length is preferably 3 to 100 mm, more preferably 3 to 50 mm, and even more preferably 4 to 10 mm.

[0050] The number of monofilaments in the fiber bundle (X) is preferably 1,500 to 30,000. In one embodiment, the number of monofilaments may be 2,000 to 25,000, 3,000 to 25,000, or 5,000 to 25,000. In one embodiment, from the viewpoint of easily achieving both dispersibility and productivity of the resin composition, the number of monofilaments in the fiber bundle (X) is preferably 1,500 to 10,000, more preferably 2,000 to 8,000, and even more preferably 2,200 to 7,000. By impregnating the multifilament, which is a bundle of monofilaments in the above number, with thermoplastic resin (B), the thermoplastic resin (B) can easily penetrate to the center of the fiber bundle (X). As a result, when the resin composition containing the fiber bundle (X) is molded, it becomes easier to obtain a molded product with a better appearance and superior mechanical strength. Furthermore, the resin has high productivity, and manufacturing problems such as fiber bundle breakage during the production of fiber bundles (X) are less likely to occur.

[0051] In one embodiment, the ratio of fibers (A) to the total mass of the fiber bundle (X) is preferably 5 to 70% by mass, more preferably 20 to 70% by mass, and even more preferably 25 to 70% by mass. Furthermore, the ratio of thermoplastic resin (B) in the fiber bundle (X) is preferably 30 to 95% by mass, more preferably 30 to 80% by mass, and even more preferably 30 to 75% by mass. By adjusting the ratio of fibers (A) to the total mass of the fiber bundle (X) within the above range, it becomes easier to obtain molded articles with good mechanical properties.

[0052] <Other Components> The resin composition according to the first embodiment may contain components other than the fiber (A) and thermoplastic resin (B) (other components), as long as they do not hinder the effects of the present invention. Examples of other components include, in addition to the other thermoplastic resins mentioned above, softeners, surface lubricants, leveling agents, antioxidants, surfactants, corrosion inhibitors, light stabilizers, ultraviolet absorbers, heat stabilizers, polymerization inhibitors, processing stabilizers, silane coupling agents, lubricants, plasticizers, crystallization accelerators, hydrolysis inhibitors, inorganic fillers, colorants, mold release agents, antistatic agents, organic fillers other than solvent-regenerated cellulose fibers, metal powders, pigments, epoxy compounds, and other additives. These additives may be used individually or in combination of two or more.

[0053] [Method for Manufacturing a Resin Composition] A second embodiment of this disclosure relates to a method for manufacturing a resin composition according to the first embodiment. That is, the second embodiment is a method for manufacturing a resin composition, the manufacturing method comprising the following (I) and (II): (I) attaching and / or absorbing a fiber stabilizer (S) containing a polyhydric alcohol to at least a part of the surface of raw material regenerated cellulose fibers to obtain the regenerated cellulose fibers (A); (II) contacting at least a part of the surface of the regenerated cellulose fibers (A) with molten thermoplastic resin (B), heat-treating the regenerated cellulose fibers (A) with the molten thermoplastic resin (B), and obtaining a resin composition containing the regenerated cellulose fibers (A) and the thermoplastic resin (B), wherein the heat treatment in (II) is performed at a temperature of 200 to 300°C. Details of the manufacturing method according to the second embodiment will be described below.

[0054] <Step (I)> The manufacturing method according to the second embodiment includes (I) attaching a fiber stabilizer (S) containing a polyhydric alcohol to at least a part of the surface of the raw material regenerated cellulose fiber, and / or absorbing the fiber stabilizer (S) containing a polyhydric alcohol to at least a part of the surface of the raw material regenerated cellulose fiber to obtain the regenerated cellulose fiber (A). Step (I) preferably includes attaching the fiber stabilizer (S) containing a polyhydric alcohol to the entire surface of the raw material regenerated cellulose fiber. "Absorbing the fiber stabilizer (S) containing a polyhydric alcohol to at least a part of the surface of the raw material regenerated cellulose fiber (raw material fiber)" includes not only incorporating the fiber stabilizer (S) containing a polyhydric alcohol into the voids (pores) within the raw material fiber, but also the raw material fiber absorbing the fiber stabilizer (S) containing a polyhydric alcohol and swelling, and the fiber stabilizer (S) containing a polyhydric alcohol being incorporated between the raw material fibers.

[0055] (Raw Fibers) The raw fibers may be short fibers of regenerated cellulose or continuous fibers. The method of producing regenerated cellulose is not particularly limited, and may be continuous fibers obtained from solvent-based regenerated cellulose such as viscose rayon, lyocell, cupro, or ionic liquid. Alternatively, it may be spun fibers obtained by twisting short fibers of regenerated cellulose together into a long thread.

[0056] In a preferred embodiment, step (I) preferably includes the following (I-1) and (I-2): (I-1) immersing the raw regenerated cellulose fibers in a medium containing a fiber stabilizer (S) containing the polyhydric alcohol; and (I-2) drying the raw regenerated cellulose fibers after the immersion.

[0057] (Step (I-1)) Step (I-1) involves immersing the raw fibers in a medium containing a fiber stabilizer (S) containing a polyhydric alcohol. Including step (I-1) makes it easier for the fiber stabilizer (S) containing the polyhydric alcohol to adhere to the entire surface of the raw fibers. It also makes it easier for the raw fibers to absorb the fiber stabilizer (S). As the medium containing the fiber stabilizer (S) containing the polyhydric alcohol, an aqueous medium is preferred. In one embodiment, the aqueous medium may be an aqueous solution containing the fiber stabilizer (S). The water component in the aqueous medium may be pure water, deionized water, tap water or industrial water, or a mixture thereof. From a cost viewpoint, the water component is preferably tap water or industrial water. The aqueous medium may also contain optional components other than the above-mentioned water component and fiber stabilizer (S).

[0058] In one embodiment, the ratio of the fiber stabilizer (S) to the total mass of the aqueous medium is preferably 0.1 to 50% by mass, more preferably 0.3 to 15% by mass, and particularly preferably 0.3 to 10% by mass. By using an aqueous medium in which the concentration of the fiber stabilizer (S) is within the above range, it becomes easier to control the ratio of the fiber stabilizer (S) to 100 parts by mass of the regenerated cellulose fiber (A) obtained in the final product to a range of 0.01 to 20 parts by mass.

[0059] The temperature of the aqueous medium is not particularly limited and can be set according to the solubility of the fiber stabilizer (S) in water.

[0060] In one preferred embodiment, it is preferable to immerse the raw fibers in an aqueous medium containing a polyhydric alcohol-containing fiber stabilizer (S) to adhere the fiber stabilizer (S) to the entire surface of the raw fibers and / or allow the raw fibers to absorb the fiber stabilizer (S), and then adjust the amount of aqueous medium attached to and / or absorbed by the raw fibers, as well as the amount of aqueous medium coexisting around the raw fibers (step (I-1')). Specifically, it is more preferable to adjust the "ratio of aqueous medium to the total mass of raw fibers before immersion in the aqueous medium" (hereinafter referred to as "aqueous medium ratio") to 200% by mass or less. By drying after adjusting the aqueous medium ratio to 200% by mass or less, drying efficiency is easily improved, and the color suppression effect of the regenerated cellulose fibers (A) obtained at the end is easily improved. The water-soluble fiber ratio can be calculated using the following formula: Water-soluble fiber ratio (%) = (W2 - W1) / W1 × 100, where W1 is the weight of the raw fibers before immersion in the water-soluble fiber, and W2 is the weight of the raw fibers after immersion in the water-soluble fiber.

[0061] (In step (I-1'), the water medium content may be adjusted to 150% by mass or less, or to 100% by mass or less. The lower limit is preferably 10% by mass or more. That is, the water medium content may be adjusted to 10 to 200% by mass, 10 to 150% by mass, or 10 to 100% by mass.)

[0062] (Step (I-2)) Step (I-2) is to dry the raw fibers after the immersion (Step (I-1)). The drying temperature is preferably room temperature (about 15 to 25°C) to 300°C, and more preferably 20 to 260°C.

[0063] (When using continuous fibers as raw material fibers) When using regenerated cellulose continuous fibers as raw material fibers, steps (I-1) and (I-2) described above may be carried out continuously while winding or taking up the regenerated cellulose continuous fibers. The following describes a preferred embodiment (when water is used as the medium) when using regenerated cellulose continuous fibers as raw material fibers (hereinafter referred to as "raw material continuous fibers").

[0064] In step (I-1), it is preferable to immerse the raw material continuous fibers in an aqueous medium containing a fiber stabilizer (S) containing a polyhydric alcohol, so that the aqueous medium adheres to and / or is absorbed by at least a portion of the surface of the raw material continuous fibers. Preferably, the process includes adhering the fiber stabilizer (S) containing a polyhydric alcohol to the entire surface of the raw material continuous fibers. Step (I-1) is preferably carried out under conditions where the immersion length of the raw material continuous fibers is 1 to 1,000 cm and the winding speed or unwinding speed of the raw material continuous fibers is 10 to 1,000 m / min. The immersion length can be arbitrarily adjusted within the range of 1 to 1,000 cm, and similarly, the winding speed or unwinding speed can also be arbitrarily adjusted within the range of 10 to 1,000 m / min. Note that "immersion length of raw material continuous fibers" refers to the length of the fibers in the portion of the raw material continuous fibers that is immersed in the aqueous medium.

[0065] In one embodiment, the amount of fiber stabilizer (S) attached may be 0.01 to 20 parts by mass, 0.01 to 10 parts by mass, or 0.03 to 5 parts by mass per 100 parts by mass of raw continuous fiber.

[0066] In one embodiment, it is preferable to include adjusting the water-media ratio of the raw continuous fibers after step (I-1) (step (I-1')). The water-media ratio can be calculated using the formula described above. By adjusting the water-media ratio, it is easier to prevent the drying time in step (I-2) from becoming too long, which would worsen production efficiency, or the thermal stability improvement effect of the resulting continuous fibers from becoming uneven. For this reason, it is preferable to perform step (I-1') after step (I-1) and before performing step (I-2). Furthermore, it is particularly preferable to perform step (I-1') from the viewpoint of controlling the amount of fiber stabilizer (S) adhering to the fibers (A).

[0067] As a method for adjusting the water medium content, it is preferable to compress the raw material continuous fibers to remove the water medium coexisting in and / or around the raw material continuous fibers, thereby setting the water medium content to a range of 200% by mass or less. In one embodiment, the water medium content may be 150% by mass or less, or 100% by mass or less. From the viewpoint of balancing the effect of improving thermal stability and the drying efficiency in process (I-2), it is preferable that the lower limit of the water medium content be 10% by mass or more.

[0068] A preferred method for compressing the raw continuous fibers is to press them against a roller or the like. More specifically, it is preferable to wind or pull the raw continuous fibers, after immersion in the aqueous medium, toward a pressure roller or the like, and bring them into contact with the pressure roller so that a constant pressure is applied to the raw continuous fibers, thereby removing the aqueous medium from the surface and / or within the raw continuous fibers and adjusting the aqueous medium ratio. In this method, the number of pressure rollers may be one or two or more. It is preferable to determine the aqueous medium ratio under specific conditions such as immersion length and winding or pulling speed by conducting a preliminary test before carrying out process (I-1), and then set the roller pressure based on those values.

[0069] In step (I-2), the drying temperature of the raw material continuous fibers is preferably 10 to 300°C, and more preferably 100 to 280°C. As for the drying method of the raw material continuous fibers, a method combining non-contact drying and contact drying is preferred from the viewpoint of being industrially feasible and easily improving production efficiency. In one embodiment, a drying method combining hot air drying and cylinder drying is more preferred, and it is particularly preferable to perform cylinder drying after hot air drying. Cylinder drying is a method of drying while bringing the raw material continuous fibers into contact with a heated cylinder. That is, it is particularly preferable that step (I-2) includes drying the raw material continuous fibers with hot air, and then further drying the raw material fibers while bringing them into contact with a heated cylinder.

[0070] When drying the raw continuous fibers with hot air, the temperature of the hot air is preferably 50 to 260°C, more preferably 80 to 200°C, and even more preferably 100 to 200°C, from the viewpoint of drying efficiency. Nitrogen is preferred as the type of hot air, but air may also be used. The time for hot air drying (non-contact drying time) can be arbitrarily adjusted by the winding speed, etc. From the viewpoint of drying efficiency and reducing the thermal history of the raw continuous fibers, 0.01 to 10 minutes is preferred, and 0.1 to 5 minutes is more preferred.

[0071] It is more preferable to perform cylinder drying (contact drying) after hot air drying (non-contact drying). From the viewpoint of drying efficiency and reducing the thermal history of the raw material continuous fibers, the cylinder temperature is preferably 50 to 260°C, more preferably 80 to 200°C, and even more preferably 100 to 200°C. Furthermore, from the viewpoint of thermal efficiency, the number of cylinders in contact with the raw material continuous fibers is preferably 3 to 50, and more preferably 5 to 30.

[0072] The manufacturing method according to the second embodiment, when using raw continuous fibers, is preferably carried out using an apparatus comprising: a storage section for storing raw continuous fibers; an immersion section equipped with a container for immersing the raw continuous fibers; a drying section for drying the raw continuous fibers; and a recovery section for recovering the fibers (A) while winding them up, or a take-up section for taking up the fibers (A) and unwinding them for other manufacturing processes. By winding up the fibers (A) in the recovery section, or taking up the fibers (A) in the take-up section, the raw continuous fibers can be unwinded from the storage section toward the immersion section and the drying section. After obtaining the fibers (A) using an apparatus comprising a storage section, an immersion section, a drying section, and a take-up section, the fibers (A) taken up by the take-up section may be unwinded into an apparatus for carrying out the next process (II).

[0073] <Step (II)> In the manufacturing method according to the second embodiment, step (II) is to bring molten thermoplastic resin (B) into contact with at least a part of the surface of regenerated cellulose fiber (A), heat-treat the regenerated cellulose fiber (A) with the molten thermoplastic resin (B), and obtain a resin composition containing the regenerated cellulose fiber (A) and the thermoplastic resin (B). Furthermore, the heat treatment in step (II) is carried out at a temperature of 200 to 300°C.

[0074] As a method for bringing the molten thermoplastic resin (B) into contact with at least a portion of the surface of the fiber (A), it is preferable to melt-knead the fiber (A) and the thermoplastic resin (B), or to impregnate the fiber (A) with the molten thermoplastic resin (B) (melt impregnation). By bringing the fiber (A) into contact with the molten thermoplastic resin (B) and heat-treating the fiber (A) with the temperature of the molten thermoplastic resin (B), not only can discoloration of the fiber (A) due to the heat load during the preparation of the resin composition be suppressed, but discoloration of the fiber (A) due to the heat load during molding the resin composition can also be suppressed. Furthermore, by heat-treating the regenerated cellulose fiber (A) containing the fiber stabilizer (S), a molded product with excellent mechanical properties can also be obtained. In one preferred embodiment, step (II) includes bringing the molten thermoplastic resin (B) into contact with the entire surface of the fiber (A). By bringing the molten thermoplastic resin (B) into contact with the entire surface of the fiber (A), it becomes easier to heat-treat the fiber (A) while preventing oxidative degradation of the fiber (A), thus further suppressing discoloration of the fiber (A).

[0075] In one embodiment, if step (II) includes melt-kneading a fiber (A) and a thermoplastic resin (B), it is preferable to put the fiber (A) and the thermoplastic resin (B) into an extruder, melt-knead them at 200 to 300°C, and then cut the strand-like material by a pelletizing method or the like to obtain a pellet-shaped resin composition. The melt-kneading temperature is more preferably 200°C to 280°C.

[0076] In one embodiment, if step (II) includes impregnating fibers (A) with molten thermoplastic resin (B) (melt impregnation), the resin composition can be obtained as the aforementioned resin-impregnated fiber bundle (X) by impregnating a fiber bundle (A1) of fibers (A) aligned in the length direction with molten thermoplastic resin (B) and then cutting it. The temperature of the molten thermoplastic resin (B) is 200 to 300°C, and more preferably 200 to 280°C.

[0077] Of the above, melt kneading is preferably used when fiber (A) is a short fiber, and melt impregnation is preferably used when fiber (A) is a long fiber or a continuous fiber. Furthermore, from the viewpoint of uniformly applying a thermal history to the fiber, it is preferable that step (II) includes melt impregnation.

[0078] If the fiber (A) is a short fiber, a method for obtaining a resin composition containing the fiber (A) may be to immerse the raw material fiber (short fiber) in a medium containing a fiber stabilizer (S) by the above-described step (I-1), and then carry out step (I-2) to dry the raw material fiber (short fiber) to obtain the short fiber (A). Alternatively, a continuous fiber (A) may be obtained in accordance with the method described above for "when continuous fibers are used as raw material fibers," and then the fiber (A) may be cut to a desired length to obtain the short fiber (A).

[0079] In other embodiments, if the fiber (A) is a short fiber, the raw material fiber (short fiber), fiber stabilizer (S), and resin (B) may be mixed and then melt-kneaded to obtain a resin composition containing the short fiber (A) and the resin (B).

[0080] Even when the fiber (A) is nanocellulose, the resin composition can be prepared in the same manner as when it is a short fiber. For example, after immersing the raw material fiber (nanocellulose) in a medium containing a fiber stabilizer (S) by step (I-1) described above, step (I-2) may be carried out to dry the raw material fiber (nanocellulose) and obtain a nanocellulose fiber (A). Alternatively, after obtaining a continuous fiber (A) in accordance with the method described above for "when continuous fibers are used as raw material fibers," the fiber (A) may be fibrillated and / or nano-sized to a desired length to obtain a nanocellulose fiber (A). In another embodiment, the raw material fiber (nanocellulose), fiber stabilizer (S), and resin (B) may be mixed and then melt-kneaded to obtain a resin composition containing a nanocellulose fiber (A) and resin (B).

[0081] <Applications> The resin composition according to the first embodiment can suppress the discoloration of regenerated cellulose fibers by heat molding, and can produce molded products with excellent mechanical properties. Therefore, it can be suitably used in fields where engineering plastics are used, such as in automotive parts and electrical and electronic product components, where discoloration and performance degradation of fibers due to heating tend to be a problem.

[0082] [Molded Articles] A third embodiment of this disclosure relates to molded articles containing a resin composition according to the first embodiment. The molded article according to the third embodiment is preferably obtained by molding the resin composition according to the first embodiment by a known resin molding method such as injection molding. The molded article according to the third embodiment has less fiber discoloration and excellent mechanical properties. Such molded articles can be suitably used in various fields such as automobiles, electrical and electronic equipment, office automation equipment, home appliances, and general merchandise.

[0083] Other embodiments of the present disclosure include the use of a polyhydric alcohol as a fiber stabilizer (S) for regenerated cellulose fibers, or a method of using such a polyhydric alcohol. The method of use may include steps (I) and (II) in the manufacturing method. Another embodiment is a method for improving the thermal stability of regenerated cellulose fibers in a thermoplastic resin (B), comprising contacting at least a portion, preferably the entire surface, of a regenerated cellulose fiber (A) containing a fiber stabilizer (S) containing a polyhydric alcohol with a molten thermoplastic resin (B), and heat-treating it at the temperature of the molten thermoplastic resin, preferably 200 to 300°C.

[0084] A non-limiting list of exemplary embodiments of the present disclosure and combinations of exemplary embodiments is given below: [1] A resin composition comprising regenerated cellulose fibers (A) containing a fiber stabilizer (S) containing a polyhydric alcohol, and a thermoplastic resin (B). [2] The resin composition according to [1], wherein the fiber stabilizer (S) is attached to at least a portion of the surface of the regenerated cellulose fibers (A) and / or penetrates at least a portion of the interior of the regenerated cellulose fibers (A). [3] The resin composition according to [1] or [2], wherein the resin composition comprises a resin-impregnated fiber bundle (X) in which the thermoplastic resin (B) is impregnated into a fiber bundle (A1) in which the regenerated cellulose fibers (A) are bundled together aligned in the longitudinal direction. [4] The resin composition according to any one of [1] to [3], wherein the polyhydric alcohol contains glycerin. A method for producing a resin composition according to any one of [5] [1] to [4], wherein the production method comprises the following (I) and (II): (I) attaching a fiber stabilizer (S) containing a polyhydric alcohol to at least a part of the surface of raw material regenerated cellulose fibers and / or absorbing it to obtain the regenerated cellulose fibers (A); (II) contacting at least a part of the surface of the regenerated cellulose fibers (A) with molten thermoplastic resin (B), heat-treating the regenerated cellulose fibers (A) with the molten thermoplastic resin (B), and obtaining a resin composition containing the regenerated cellulose fibers (A) and the thermoplastic resin (B), wherein the heat treatment in (II) is performed at a temperature of 200 to 300°C. [6] A method for producing a resin composition according to [5], wherein (I) comprises the following (I-1) and (I-2): (I-1) immersing the raw material regenerated cellulose fibers in a medium containing a fiber stabilizer (S) containing the polyhydric alcohol; (I-2) drying the raw material regenerated cellulose fibers after immersion. [7] A method for producing a resin composition according to [5] or [6], wherein (II) comprises contacting the entire surface of the regenerated cellulose fibers (A) with the molten thermoplastic resin (B).[8] A method for producing the resin composition according to [6] or [7], wherein the raw material regenerated cellulose fiber is a continuous regenerated cellulose fiber, and (I-1) and (I-2) are carried out continuously while winding or unwinding the continuous regenerated cellulose fiber. [9] A molded article comprising the resin composition according to any one of [1] to [4].

[0085] The present disclosure will be further illustrated by the following examples, but these examples will not limit the interpretation of the present disclosure.

[0086] The following materials were used as raw fibers and fiber stabilizers (S). <Raw Fibers> ・Regenerated cellulose continuous fibers: Regenerated cellulose fiber bundles (lyocell) obtained by the solvent method. Average fiber diameter: 11 μm, 552 tex, 2,700 filaments. <Fiber Stabilizers (S)> ・Polyhydric alcohol: Glycerin. <Thermoplastic Resin (B)> ・Polypropylene resin (homopolypropylene resin, manufactured by Sun Allomer Co., Ltd., product name "PMB02A"). <Other Fiber Treatment Agents> ・Boric acid. <Additives> ・Maleic anhydride modified polypropylene resin: Manufactured by SK Functional Polymer, product name "OREVAC (registered trademark) CA100". ・Hindered phenol antioxidant: Manufactured by BASF Japan Ltd., product name "Irganox (registered trademark) 1010FF". - Hindered amine light stabilizer: Manufactured by BASF Japan Ltd., product name "Tinuvin® 111 FDL". - Phosphorus processing stabilizer: Manufactured by BASF Japan Ltd., product name "Irgafos® 168".

[0087] [Example 1, Comparative Examples 1-2] <Preparation of Regenerated Cellulose Continuous Fibers> Using a device (Minisizer, manufactured by Kaji Seisakusho Co., Ltd., product name "DCC001P") equipped with a storage section for storing raw material continuous fibers, an immersion section with a container for storing a medium containing a fiber stabilizer (S), a drying section with a non-contact dryer and a contact dryer, and a recovery section for recovering the processed continuous fibers, regenerated cellulose continuous fibers of Example 1 and Comparative Example 2 were prepared under the conditions shown in Table 1 while winding the raw material continuous fibers toward the recovery section. The winding speed was 20 m / min. The coloration of the regenerated cellulose continuous fibers obtained by the manufacturing method of each example was evaluated under the following condition 1.

[0088] <Preparation of Resin Composition> Next, the thermoplastic resin (B) and additives were mixed in the proportions shown in Table 1 and fed into a twin-screw extruder (manufactured by Japan Steel Works Ltd., product name "TEX30α"). The mixture was then melt-kneaded at a cylinder temperature of 280°C, and the resulting molten mixture was impregnated into two bundles of regenerated cellulose continuous fibers (2,700 filaments / bundle × 2 bundles = 5,400 filaments) passed through a crosshead die. After that, the bundles were shaped using a shaping nozzle at the crosshead die outlet, shaped with a shaping roll, and then cut to a length of 7 mm using a pelletizer to obtain resin composition pellets. As Comparative Example 1, resin composition pellets were obtained from raw material continuous fibers under the same conditions as above. Next, the resin compositions (pellets) of each example were injection-molded under the following conditions to obtain molded products (ISO multipurpose test pieces). Various mechanical properties were measured for the obtained molded products under the following conditions. The coloration of the fibers in the molded products was also evaluated under the following condition 2. (Molding conditions) Molding machine: FUNAC Corporation, product name "α-S150iA". Test specimen: ISO multipurpose test specimen. Molding temperature: 200℃. Mold temperature: 60℃.

[0089] <Condition 1: Evaluation of Fiber Coloration> The regenerated cellulose continuous fibers of Example 1 and Comparative Examples 1-2 were heated in an oven at 240°C for 11 minutes to evaluate the fiber coloration. In addition, the regenerated cellulose continuous fibers of Example 1 and Comparative Example 1 were heated in an oven at 260°C for 10 minutes to evaluate the fiber coloration. The coloration level of the regenerated cellulose continuous fibers of each example after heating was evaluated according to the following criteria. The coloration level was evaluated in the following three stages, with the color of the blank (Comparative Example 1, untreated product) after heating being set as Level 2. (Coloration Level) Level 1: Less coloration than the blank. Level 2: Similar color to the blank. Level 3: More coloration than the blank.

[0090] <Condition 2: Evaluation of molded product coloring> After preheating the mold at 240°C for 30 seconds, the ISO multipurpose test specimen prepared above was placed in the mold and compressed and heated at 240°C for 2 minutes and 30 seconds. After cooling to room temperature, the molded product was removed and the coloring level of the fibers inside the molded product was evaluated according to the same criteria as in Condition 1.

[0091] [Mechanical property evaluation of molded products] <Measurement of tensile strength> Using the obtained ISO multipurpose test specimens, the tensile strength was measured in accordance with ISO 527-1 and 527-2. Specifically, a tensile testing machine (manufactured by Shimadzu Corporation, product name "Autograph® AG-20kNXDplus") was used, and the measurement was performed under the following conditions: temperature: 23°C, test speed: 5 mm / min, and chuck distance (span) 115 mm.

[0092] <Measurement of Flexural Modulus> The obtained ISO multipurpose test specimens were measured in accordance with ISO 178. Specifically, a tensile testing machine (manufactured by Toyo Seiki Seisakusho Co., Ltd., product name "Bendgraph II") was used, with the following conditions: temperature: 23°C, test speed: 2 mm / min, and chuck distance (span) 64 mm.

[0093] <Measurement of Charpy Impact Strength> The obtained ISO multipurpose test specimens were measured in accordance with ISO 179 / 1eA. Specifically, a digital impact tester (manufactured by Yasuda Seiki Seisakusho Co., Ltd., product name "Impact Tester No. 258-L IMPACT TESTER") was used, and the measurements were taken under the following conditions: test temperature: 23°C, measurement mode: with V-shaped notch, hammer capacity: 4J.

[0094]

[0095] As shown in Table 1, the molded article obtained from the resin composition of Example 1 had less discoloration than Comparative Example 1 (untreated). Furthermore, it had a higher flexural modulus and better mechanical properties than Comparative Example 1. On the other hand, Comparative Example 2, which contained boric acid-treated regenerated cellulose fibers, had a lower level of discoloration of the fibers themselves than Comparative Example 1. However, when the fibers were incorporated into the resin composition and heat-molded, they became more discolored than those in Comparative Example 1. Furthermore, although the molded article of Comparative Example 2 had a higher flexural modulus than Comparative Example 1, its tensile strength and Charpy impact strength were lower. From these results, it was found that the resin composition according to the first embodiment can suppress discoloration of regenerated cellulose fibers during heat molding, and yields molded articles with excellent mechanical properties. It should be noted that the manufacturing method according to the second embodiment can also be industrially produced, for example, by using the apparatus used in the examples.

[0096] The resin composition according to the first embodiment can suppress the discoloration of regenerated cellulose fibers by heat molding and can produce molded products with excellent mechanical properties. Such resin compositions can be suitably used in fields such as automotive parts and electrical and electronic product components, where engineering plastics are used.

Claims

1. A resin composition comprising a regenerated cellulose fiber (A) containing a polyhydric alcohol-containing fiber stabilizer (S), and a thermoplastic resin (B).

2. The resin composition according to claim 1, wherein the fiber stabilizer (S) is attached to at least a portion of the surface of the regenerated cellulose fiber (A) and / or penetrates at least a portion of the interior of the regenerated cellulose fiber (A).

3. The resin composition according to claim 1 or 2, wherein the resin composition comprises a resin-impregnated fiber bundle (X) in which the thermoplastic resin (B) is impregnated into a fiber bundle (A1) obtained by bundling the regenerated cellulose fibers (A) aligned in the longitudinal direction.

4. The resin composition according to claim 1 or 2, wherein the polyhydric alcohol comprises glycerin.

5. A method for producing a resin composition according to claim 1 or 2, wherein the production method comprises the following (I) and (II): (I) attaching and / or absorbing a fiber stabilizer (S) containing a polyhydric alcohol to at least a portion of the surface of raw material regenerated cellulose fibers to obtain the regenerated cellulose fibers (A); (II) contacting at least a portion of the surface of the regenerated cellulose fibers (A) with molten thermoplastic resin (B), heat-treating the regenerated cellulose fibers (A) with the molten thermoplastic resin (B), and obtaining a resin composition containing the regenerated cellulose fibers (A) and the thermoplastic resin (B), wherein the heat treatment in (II) is performed at a temperature of 200 to 300°C.

6. A method for producing a resin composition according to claim 5, wherein (I) comprises the following (I-1) and (I-2): (I-1) immersing the raw material regenerated cellulose fibers in a medium containing a fiber stabilizer (S) containing the polyhydric alcohol; and (I-2) drying the raw material regenerated cellulose fibers after the immersion.

7. A method for producing a resin composition according to claim 5, wherein (II) comprises contacting the entire surface of the regenerated cellulose fiber (A) with the molten thermoplastic resin (B).

8. The method for producing a resin composition according to claim 6, wherein the raw material regenerated cellulose fiber is a continuous regenerated cellulose fiber, and steps (I-1) and (I-2) are carried out continuously while winding or unwinding the continuous regenerated cellulose fiber.

9. A molded article comprising the resin composition according to claim 1 or 2.

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