Resin composition, method for producing the same, pellet, and molded article

Abstract

To provide a resin composition, a method for producing the same, a pellet containing the resin composition, and a molded article, allowing the production of a molded article having low discoloration and superior mechanical properties.SOLUTION: A resin composition comprises, relative to the total mass of the resin composition, 40 to 97 mass% of a thermoplastic resin (A) including a polyacetal resin (a1), 3 to 60 mass% of regenerated cellulose fibers (B), and 0.01 to 0.5 mass% of one or more additives (C) selected from polyamide-epichlorohydrin resins, polyamine-epichlorohydrin resins, and melamine resins, provided that the total of (A) to (C) does not exceed 100 mass%.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition, a method for producing the same, pellets, and molded articles thereof. [Background technology]

[0002] Toward the creation of a sustainable society, composite resin materials that combine petroleum-derived resin components with biomass components are increasingly being utilized. Examples of such composite resin materials include regenerated cellulose fiber-containing resin compositions in which regenerated cellulose fibers are filled into a thermoplastic resin (see, for example, Patent Documents 1 and 2). Lightweight molded articles with excellent mechanical properties can be obtained from such regenerated cellulose fiber-containing resin compositions. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2013-091775 [Patent Document 2] Japanese Patent Application Laid-Open No. 2016-020465 Summary of the Invention [Problem to be solved by the invention]

[0004] Polyacetal resin is known as a typical engineering resin with excellent physical properties, such as mechanical and electrical properties, and chemical properties, such as chemical resistance and heat resistance. It is expected that combining such polyacetal resin with regenerated cellulose fibers will result in molded articles with even better mechanical properties. However, the inventors of the present application have found that a formulation that simply combines polyacetal resin with regenerated cellulose fibers is difficult to achieve the desired mechanical properties and that such a formulation tends to result in molded articles that are easily discolored.

[0005] An object of the present disclosure is to provide a resin composition that can give a molded article with little coloration and excellent mechanical properties, a method for producing the same, and pellets and molded articles containing the resin composition. [Means for solving the problem]

[0006] As a result of intensive research, the inventors of the present application have found that the above-mentioned problems can be solved by a resin composition containing, relative to the total mass of the resin composition, 40 to 97 mass% of a thermoplastic resin (A) including a polyacetal resin (a1), 3 to 60 mass% of regenerated cellulose fibers (B), and 0.01 to 0.5 mass% of one or more additives (C) selected from polyamide epichlorohydrin resin, polyamine epichlorohydrin resin, and melamine resin (provided that the total of (A) to (C) does not exceed 100 mass%). [Effects of the Invention]

[0007] According to the present disclosure, it is possible to provide a resin composition and a method for producing the same, as well as pellets and molded articles containing the resin composition, which are capable of producing molded articles with little coloration and excellent mechanical properties. DETAILED DESCRIPTION OF THE INVENTION

[0008] An embodiment of the present disclosure will be described in detail below, but the scope of the present disclosure is not limited to the embodiment described herein, and various modifications can be made without departing from the spirit of the present disclosure. Furthermore, when multiple numerical ranges are described for a specific parameter, any of the numerical values ​​described therein can be combined to form a suitable numerical range. Furthermore, the lower and / or upper limits of a numerical range described in this disclosure are numerical values ​​within that range and may be replaced with numerical values ​​shown in the examples. The expression "X to Y" indicating a numerical range means "X or more and Y or less." When a specific description given for one embodiment also applies to other embodiments, that description may be omitted in other embodiments.

[0009] [Resin composition] A first embodiment of the present disclosure relates to a resin composition. The resin composition according to the first embodiment contains, relative to the total mass of the resin composition, 40 to 97 mass% of a thermoplastic resin (A) containing a polyacetal resin (a1), 3 to 60 mass% of regenerated cellulose fibers (B), and 0.01 to 0.5 mass% of one or more additives (C) selected from polyamide epichlorohydrin resin, polyamine epichlorohydrin resin, and melamine resin (provided that the total of (A) to (C) does not exceed 100 mass%). The resin composition according to the first embodiment can provide a molded article that is less discolored and has excellent mechanical properties.

[0010] <Thermoplastic resin (A)> The resin composition according to the first embodiment contains a thermoplastic resin (A) containing a polyacetal resin (a1). By combining the thermoplastic resin (A) containing the polyacetal resin (a1) (hereinafter referred to as "resin (A)") with regenerated cellulose fibers (B) and an additive (C) described below, a molded product with little coloring and excellent mechanical properties can be obtained.

[0011] The proportion of the resin (A) in the resin composition according to the first embodiment is 40 to 97 mass %, preferably 45 to 95 mass %, more preferably 50 to 90 mass %, relative to the total mass of the resin composition.

[0012] (Polyacetal resin (a1)) The resin composition according to the first embodiment contains a polyacetal resin (a1) (hereinafter referred to as "resin (a1)"). Resin (a1) is a thermoplastic resin containing an oxymethylene unit (-CHO-) as a main structural unit. In the present disclosure, the term "main structural unit" refers to a monomer unit that accounts for more than 50% by mass, preferably 70% by mass or more, of all structural units (100% by mass) that constitute resin (a1). Resin (a1) may be a homopolymer containing only oxymethylene units, or a copolymer containing comonomer units other than oxymethylene units. Here, the term "comonomer unit" refers to a monomer unit derived from a monomer (comonomer) copolymerizable with the monomer (main monomer) that constitutes the oxymethylene unit.

[0013] Homopolymer The homopolymer of resin (a1) can be obtained by anionic polymerization of formaldehyde in the presence of a polymerization catalyst. The terminals of the crude polyoxymethylene obtained in the polymerization step must be stabilized using an etherifying agent, an esterifying agent, or the like. When resin (a1) is a homopolymer, the degree of polymerization of the homopolymer can be appropriately adjusted, for example, within a range that satisfies the melt flow rate described below.

[0014] Copolymer The copolymer of resin (a1) can be obtained by copolymerizing trioxane with a comonomer copolymerizable with trioxane in the presence of a polymerization catalyst. Trioxane is a cyclic trimer of formaldehyde. Trioxane is generally obtained by reacting an aqueous formaldehyde solution in the presence of an acidic catalyst, and can be used after being purified by a method such as distillation.

[0015] The comonomer is preferably selected from the group consisting of cyclic ethers and cyclic formals having at least one carbon-carbon bond. Examples include 1,3-dioxolane, diethylene glycol formal, 1,4-butanediol formal, 1,3-dioxane, ethylene oxide, propylene oxide, epichlorohydrin, etc. Among these, from the viewpoint of polymerization stability, 1,3-dioxolane and 1,4-butanediol formal are preferred, and 1,3-dioxolane is more preferred. Furthermore, as the comonomer, a compound having two polymerizable cyclic ether groups or cyclic formal groups, such as diglycidyl ether of alkylene glycol, e.g., butanediol diglycidyl ether, or diformal, or a compound having three or more polymerizable cyclic ether groups or cyclic formal groups, such as glycerin triglycidyl ether, trimethylolpropane triglycidyl ether, or pentaerythritol tetraglycidyl ether, may be used.

[0016] The copolymer can be polymerized by a known method using a known polymerization apparatus such as a batch type or continuous type.

[0017] When the resin (a1) is a copolymer, the copolymer may be any of a random copolymer, a block copolymer, and a graft copolymer. From the viewpoint of thermal stability, a random copolymer is preferable. The polymerization degree, branching degree, and crosslinking degree of the copolymer may be appropriately adjusted within a range that satisfies the melt flow rate described below.

[0018] As described above, the resin (a1) may be a homopolymer or a copolymer, but from the viewpoint of thermal stability, the resin (a1) preferably contains a copolymer. In one embodiment, the proportion of comonomer units in the resin (a1) is preferably 1 to 20 mass% and more preferably 1 to 10 mass% relative to the total structural units of the copolymer (100 mass%). In a preferred embodiment, the resin (a1) contains a copolymer containing one or more comonomer units selected from 1,3-dioxolane and 1,4-butanediol formal in an amount of 1 to 20 mass% relative to the total structural units. The proportion of comonomer units in the resin (a1) is 1 For example, a sample is prepared by dissolving the resin (a1) in deuterated 1,1,1,3,3,3-hexafluoroisopropanol (HFIP) to a concentration of 5% by mass. 1 It can be calculated by a method of analyzing the resin (a1) by H-NMR and determining the ratio of the integral value of the comonomer unit to the integral value of the peaks of all the monomers in the resin (a1).

[0019] Melt flow rate In one embodiment, the melt flow rate of resin (a1) (190°C, 2.16 kg load) is preferably more than 1 g / 10 min and not more than 60 g / 10 min. When the melt flow rate of resin (a1) (190°C, 2.16 kg load) is more than 1 g / 10 min and not more than 60 g / 10 min, for example, when the resin composition is injection molded to obtain a molded article, the flowability is likely to be improved and a molded article with excellent mechanical properties is likely to be obtained. In a more preferred embodiment, the melt flow rate of resin (a1) (190°C, 2.16 kg load) may be 2 to 55 g / 10 min, 2 to 50 g / 10 min, or 2.5 to 45 g / 10 min. The melt flow rate of resin (a1) (190°C, 2.16 kg load) can be adjusted to the above range by adding a known molecular weight modifier during polymerization. The melt flow rate of the resin (a1) (190°C, 2.16 kg load) can be measured in accordance with ISO 1133 (condition D). The melt flow rate can be measured using a melt flow rate tester (for example, product name "Melt Indexer L220" manufactured by Tateyama Scientific High-Technologies Co., Ltd.).

[0020] In the resin composition according to the first embodiment, the resin (A) preferably contains the resin (a1) as a main component. Here, "containing the resin (a1) as a main component" means that the proportion of the resin (a1) relative to the total mass of the resin (A) is greater than 50% by mass. The proportion of the resin (a1) relative to the total mass of the resin (A) is preferably 70% by mass or more, more preferably 90% by mass or more. Alternatively, the resin (A) may contain only the resin (a1).

[0021] (Other thermoplastic resins (a2)) In one embodiment, the resin (A) may contain a thermoplastic resin other than the resin (a1) (another thermoplastic resin (a2), hereinafter also referred to as "resin (a2)"). Any thermoplastic resin can be selected as resin (a2) as long as it does not impair the effects of the present disclosure. Examples of suitable resins include olefin-based resins (polyethylene-based resins, polypropylene-based resins, etc.), vinyl alcohol-based resins, vinyl ester-based resins, styrene-based resins, (meth)acrylate-based resins, polyester-based resins, polycarbonate-based resins, polyamide-based resins, polysulfone-based resins, polyphenylene-based resins, polyacetal-based resins other than resin (a1), and thermoplastic elastomers. Biodegradable resins and biomass resins can also be used. Resin (a2) may contain either an olefin-based resin or a polypropylene-based resin. When resin (A) contains resin (a2), the amount of resin (a2) is preferably 10% by mass or less, more preferably 5% by mass or less, of the total mass of resin (A) from the viewpoint of the mechanical properties of the molded article.

[0022] In a particularly preferred embodiment, from the viewpoint of easily obtaining a molded article having excellent mechanical properties, the resin (A) contains only the resin (a1).

[0023] <Regenerated cellulose fiber (B)> The resin composition according to the first embodiment contains regenerated cellulose fibers (B). The proportion of the regenerated cellulose fibers (B) in the resin composition according to the first embodiment is 3 to 60% by mass, preferably 5 to 55% by mass, and more preferably 10 to 50% by mass. In this disclosure, "regenerated cellulose fibers" refers to artificially spun cellulose fibers using natural cellulose fibers (cellulose fibers derived from plants, cellulose fibers derived from animals (such as sea squirt cellulose), and cellulose fibers derived from bacteria).

[0024] Methods for obtaining regenerated cellulose fibers from natural cellulose fibers include, for example, the viscose method, the cuprammonium method, and the solvent spinning method (a method in which cellulose is directly spun without first being chemically converted; hereinafter referred to as the "solvent method"). Examples of regenerated cellulose fibers obtained by the viscose method include viscose rayon, polynosic, and modal. Examples of regenerated cellulose fibers obtained by the cuprammonium method include cupra. Examples of regenerated cellulose fibers obtained by the solvent method include lyocell and regenerated cellulose fibers obtained by the ionic liquid method. As the regenerated cellulose fiber (B), one type of regenerated cellulose fiber obtained by these methods may be used alone, or two or more types may be used in combination. In addition, spun fibers made by twisting short regenerated cellulose fibers into long threads may also be used. In one embodiment, the regenerated cellulose fibers (B) may include one or more selected from viscose process regenerated cellulose fibers, cuprammonium process regenerated cellulose fibers, and solvent process regenerated cellulose fibers.

[0025] From the viewpoint of easily suppressing discoloration of the molded article, it is preferable to include solvent-process regenerated cellulose fibers as the regenerated cellulose fibers (B). As the solvent-process regenerated cellulose fibers, the above-mentioned lyocell, regenerated cellulose fibers obtained by the ionic liquid method, etc. may be used alone or in combination of two or more kinds.

[0026] Average fiber length In one embodiment, the average fiber length of the regenerated cellulose fibers (B) in the resin composition is preferably 100 μm or more. By including regenerated cellulose fibers (B) in the resin composition having an average fiber length of 100 μm or more, a molded product having more excellent mechanical properties can be easily obtained. From the viewpoint of manufacturability, the upper limit of the average fiber length of the regenerated cellulose fibers (B) in the resin composition is preferably 5,000 μm or less. In one embodiment, the average fiber length of the regenerated cellulose fibers (B) in the resin composition is preferably 100 to 5,000 μm, more preferably 120 to 1,500 μm, and even more preferably 150 to 500 μm. Note that "the average fiber length of the regenerated cellulose fibers (B) in the resin composition is 100 μm or more" can be easily achieved by blending raw material regenerated cellulose fibers (B) with an average fiber length of 1 mm or more in the resin composition.

[0027] The average fiber length of the regenerated cellulose fibers (B) in the resin composition can be calculated as the average value of the fiber lengths (length of each fiber) measured by dissolving and removing the resin components in the resin composition with an organic solvent (e.g., xylene), dispersing the regenerated cellulose fibers (B) in a medium, and performing image processing on the fibers (B). When the resin composition is a thermoplastic resin-impregnated regenerated cellulose fiber bundle (B-1) described below, the average fiber length can be calculated by measuring the major axis lengths of approximately 100 pellets of the fiber bundle (B-1) with a vernier caliper or the like and averaging the measured values.

[0028] Average fiber diameter In one embodiment, the regenerated cellulose fibers (B) preferably have an average fiber diameter of 5 to 30 μm and an X-ray orientation degree of 86% or more. By having such an average fiber diameter and X-ray orientation degree, the regenerated cellulose fibers (B) are easily impregnated with the resin (A) when preparing the thermoplastic resin-impregnated regenerated cellulose fiber bundle (B-1) described below. Furthermore, the mechanical strength of the resulting molded article is also likely to be improved. The average fiber diameter is more preferably 6 to 20 μm, and even more preferably 7 to 15 μm. The average fiber diameter of the regenerated cellulose fibers (B) can be calculated from the average diameter of a plurality of fibers observed with an SEM or the like. The degree of X-ray orientation is more preferably 90% or more. The degree of X-ray orientation of the regenerated cellulose fibers (B) can be determined from the formulas described in JP-A-9-31744 and JP-A-9-256216.

[0029] (Thermoplastic resin impregnated regenerated cellulose fiber bundle (B-1)) The resin composition according to the first embodiment preferably contains a thermoplastic resin-impregnated regenerated cellulose fiber bundle (B-1) (hereinafter referred to as "fiber bundle (B-1)") in which a fiber bundle of regenerated cellulose fibers (B) aligned in the longitudinal direction is impregnated with a resin (A) containing an additive (C) described below. A method for preparing the fiber bundle (B-1) will be described later, and the additive (C) contained in the fiber bundle (B-1) may be contained in the resin (A) or may be attached to the regenerated cellulose fibers (B). In either case, the additive (C) is contained in the impregnated resin (A), and therefore, in the description of the fiber bundle (B-1), it will be referred to as "a fiber bundle (B-1) impregnated with a resin (A) containing an additive (C)." By including the fiber bundle (B-1) in the resin composition according to the first embodiment, a molded article having excellent mechanical properties can be obtained. In one embodiment, the resin composition may include the fiber bundle (B-1) and any thermoplastic resin (for example, the above-mentioned resin (a2)), or may include only the fiber bundle (B-1).

[0030] From a resin composition containing the fiber bundle (B-1), a molded article having excellent mechanical properties can be easily obtained. Furthermore, a molded article having little coloring can be easily obtained. A particularly preferred embodiment of the present invention is a fiber bundle (B-1) obtained by bundling solvent-process regenerated cellulose fibers aligned in the length direction and impregnating the fiber bundle with a resin (a1) containing the additive (C) described below.

[0031] The resin (A) contained in the fiber bundle (B-1) can be exemplified in the same manner as the resin (A) described above, and preferred examples are also the same. That is, the proportion of the resin (a1) in the resin (A) is preferably more than 50% by mass, more preferably 70% by mass or more, and even more preferably 90% by mass or more. The proportion of the resin (a1) in the impregnated resin (A) may be 100% by mass.

[0032] The proportions of the resin (A), regenerated cellulose fiber (B), and additive (C) described below in the fiber bundle (B-1) can be within the same ranges as the proportions of each component in the resin composition. That is, the total mass of the fiber bundle (B-1) can be 40 to 97 mass% of the resin (A), 3 to 60 mass% of the regenerated cellulose fiber (B), and 0.01 to 0.5 mass% of one or more additives (C) selected from polyamide epichlorohydrin resin, polyamine epichlorohydrin resin, and melamine resin (provided that the total of (A) to (C) does not exceed 100 mass%). In one embodiment, in addition to the components (A) to (C), the fiber bundle (B-1) can contain 0.001 to 0.05 mass% of the phosphonium salt (D) described below (provided that the total of (A) to (D) does not exceed 100 mass%). The proportion of each component in the fiber bundle (B-1) can be set within any desired range, the same as that of the resin composition, within the above range or the range described below.

[0033] The number of regenerated cellulose fibers (B) in the fiber bundle (B-1) is preferably adjusted to a range of 100 to 30,000. In one embodiment, the number of regenerated cellulose fibers (B) is preferably 2,000 to 30,000, more preferably 3,000 to 25,000, and even more preferably 5,000 to 25,000.

[0034] (Method for producing thermoplastic resin-impregnated regenerated cellulose fiber bundle (B-1)) In one embodiment, the fiber bundle (B-1) can be produced by a known production method using a die. Specifically, the production methods described in JP-A-6-313050, JP-A-2007-176227, JP-B-6-2344, etc. can be applied. The production method of the resin composition, including the preparation of the fiber bundle (B-1), will be described in detail later.

[0035] <Additive (C)> The resin composition according to the first embodiment is characterized by containing the above-mentioned resin (A), regenerated cellulose fibers (B), and one or more additives (C) selected from polyamide epichlorohydrin resins, polyamine epichlorohydrin resins, and melamine resins. The present inventors have found that by including a specific amount of additive (C), discoloration of the resulting molded article is suppressed, and furthermore, molded articles with improved mechanical properties are obtained compared to those obtained with a formulation that does not include additive (C), although the exact reason for this is unknown.

[0036] The additive (C) is one or more resin components selected from polyamide epichlorohydrin resins, polyamine epichlorohydrin resins, and melamine resins.

[0037] Polyamide epichlorohydrin resins and polyamine epichlorohydrin resins are produced by reacting an epihalohydrin, typically epichlorohydrin, with nitrogen atoms in the main chain of a condensed polyvalent acid, a polyamine polyalkylpolyamine, or urea, and contain a cationic quaternary amine and a reactive functional group. Polyamide epichlorohydrin resins also include polyamide polyamine epichlorohydrin resins. It is believed that the reactive functional groups of polyamide epichlorohydrin resins and polyamine epichlorohydrin resins react with hydroxyl groups, carboxyl groups, etc. of cellulose to strengthen the bonds between fibers. Therefore, by combining a polyamide epichlorohydrin resin and / or a polyamine epichlorohydrin resin with a resin (A) containing resin (a1), mechanical properties tend to be improved. The cationic quaternary amine is preferably a cyclic amino group having a four-membered ring or less, such as an aziridinium group or an azetidinium group, and more preferably an azetidinium group, which has both the properties of a quaternary amine and that of a reactive functional group. In one embodiment, the polyamide epichlorohydrin resin preferably contains azetidinium and / or aziridinyl groups.

[0038] As the polyamide epichlorohydrin resin and polyamine epichlorohydrin resin, for example, those having a viscosity of 5 to 1,000 mPa·s in a 25% aqueous solution at 25° C. can be preferably used. Commercially available polyamide epichlorohydrin resins and polyamine epichlorohydrin resins may also be used, such as the Sumirez (registered trademark) Resin series manufactured by Taoka Chemical Co., Ltd. (e.g., "Sumirez Resin SLX-1" (polyamide epichlorohydrin resin)), the Arafix (registered trademark) series manufactured by Arakawa Chemical Industries, Ltd. (e.g., "Arafix 2550P" (polyamide polyamine epichlorohydrin resin), and the WS series manufactured by Hoshikawa PMC Corporation (e.g., "WS4011" (polyamine epichlorohydrin resin)).

[0039] The melamine resin is not particularly limited as long as it exhibits the effects of the present disclosure, and examples thereof include melamine-formaldehyde resins such as methylated melamine resins obtained by reacting melamine with formaldehyde; and melamine-formaldehyde co-condensation resins obtained by substituting a portion of the melamine with a component that can co-condense with melamine and formaldehyde. Examples of the co-condensable component include ureas such as urea, ethyleneurea, and thiourea; guanamines such as benzoguanamine, acetoguanamine, phenylacetoguanamine, formguanamine, and CTU guanamine; amino compounds such as guanidine, dicyandiamide, and paratoluenesulfonamide; phenols such as phenol, cresol, xylenol, ethylphenol, butylphenol, and bisphenol A; and other compounds such as xylene and sucrose. These components may be used alone or in combination of two or more.

[0040] The additive (C) is one or more resin components selected from the polyamide epichlorohydrin resin, polyamine epichlorohydrin resin, and melamine resin. Among these, it is preferable to contain a polyamide epichlorohydrin resin and / or a polyamine epichlorohydrin resin, from the viewpoint of easily obtaining a molded article having excellent mechanical properties. When the additive (C) contains the polyamide epichlorohydrin resin and / or the polyamine epichlorohydrin resin, the tensile strain at break of the molded article is likely to be improved.

[0041] The content of additive (C) in the resin composition according to the first embodiment is 0.01 to 0.5% by mass, based on the total mass of the resin composition. When the content of additive (C) is 0.01% by mass or more, a molded article with little coloration and excellent mechanical properties can be obtained. The inventors of the present application have found that an excessively high content of additive (C) can result in a deterioration in the mechanical properties of the molded article. Therefore, from the viewpoint of achieving both coloration and good mechanical properties of the molded article, the content of additive (C) in the resin composition is set to 0.01 to 0.5% by mass. The content of additive (C) can be any value within the above range. However, from the viewpoint of easily achieving both coloration and good mechanical properties of the molded article, the content is preferably 0.01% by mass or more and less than 0.4% by mass, more preferably 0.03% by mass or more and less than 0.4% by mass, and even more preferably 0.05 to 0.3% by mass.

[0042] In one embodiment, the proportion of the additive (C) relative to 100 parts by mass of the resin (A) is preferably 0.01 to 1.25 parts by mass, more preferably 0.05 to 1.20 parts by mass, and even more preferably 0.1 to 1.10 parts by mass. In one embodiment, the proportion of the additive (C) relative to 100 parts by mass of the regenerated cellulose fibers (B) is preferably 0.02 to 16.7 parts by mass, more preferably 0.1 to 5 parts by mass, and even more preferably 0.3 to 4 parts by mass.

[0043] <Phosphonium Salt (D)> The resin composition according to the first embodiment can further contain a phosphonium salt (D) in addition to the above-described components (A) to (C). When the resin composition contains the phosphonium salt (D), the mechanical properties (for example, tensile strength at break) of the resulting molded article tend to be further improved. Examples of the phosphonium salt (D) include tetraphenylphosphonium bromide, tetrabutylphosphonium bromide, methyltriphenylphosphonium bromide, methyltriphenylphosphonium iodide, methyltriphenylphosphonium chloride, ethyltriphenylphosphonium bromide, n-butyltriphenylphosphonium bromide, methoxymethyltriphenylphosphonium chloride, benzyltriphenylphosphonium chloride, carboxyethyltriphenylphosphonium bromide, tetraphenylphosphonium bromide, etc. Among these, from the viewpoint of promoting the reaction between the resin, the fiber, and the additives, it is preferable to contain methyltriphenylphosphonium bromide, ethyltriphenylphosphonium bromide, or tetraphenylphosphonium bromide, and it is more preferable to contain methyltriphenylphosphonium bromide.

[0044] When the resin composition contains the phosphonium salt (D), the content thereof is preferably 0.001 to 0.05 mass%, more preferably 0.005 to 0.01 mass%, relative to the total mass of the resin composition. When the content of the phosphonium salt (D) is within the above range, the mechanical properties of the obtained molded article tend to be improved.

[0045] <Other ingredients (E)> The resin composition according to the first embodiment may contain components other than the resin (A), regenerated cellulose fibers (B), additive (C), and phosphonium salt (D) (other components (E)) within the range that does not impair the effects of the present invention. Examples of other components include softeners, surface lubricants, leveling agents, antioxidants, surfactants, corrosion inhibitors, light stabilizers, UV absorbers, heat stabilizers, polymerization inhibitors, silane coupling agents, lubricants, plasticizers, crystallization accelerators, hydrolysis inhibitors, inorganic fillers, colorants, mold release agents, antistatic agents, organic fillers other than the regenerated cellulose fibers (B), metal powders, pigments, epoxy compounds, and binder resins (excluding the resin (A) and additive (C)). These additives may be used alone or in combination of two or more.

[0046] When the resin composition contains the aforementioned other component (E), the amount of the other component (E) can be 1 mass % or less based on the total mass of the resin composition. The other component (E) may be blended during the production of the fiber bundle (B-1), or may be attached to at least a part of the surface of pellets of the resin composition described below.

[0047] [Method of producing resin composition] The second embodiment of the present disclosure relates to a method for producing the resin composition according to the first embodiment. The production method according to the second embodiment can include preparing a mixture or regenerated cellulose fibers that serve as a precursor (step (1)), and then obtaining a resin composition from the precursor (step (2)). In one embodiment, the production method according to the second embodiment preferably includes preparing a mixture containing the thermoplastic resin (A) and the additive (C) (step (1-1)), or preparing the regenerated cellulose fibers (B) to which the additive (C) is attached (step (1-2)). Each step will be described in detail below.

[0048] <Process (1)> (Process (1-1) Step (1-1) is to prepare a mixture containing resin (A) and additive (C). Step (1-1) may include adding additive (C) to resin (A) to obtain a mixture.

[0049] When additive (C) is added to resin (A), the amount of additive (C) added is adjusted so that the proportion of additive (C) in the final resin composition is 0.01 to 0.5 mass%. In one embodiment, additive (C) may be added in an amount of 0.01 to 1.25 parts by mass, 0.05 to 1.20 parts by mass, or 0.1 to 1.10 parts by mass per 100 parts by mass of resin (A). The additive (C) can be added to the resin (A) by pre-blending using a coil screw or rocking mixer, for example.

[0050] <Process (1-2)> Step (1-2) involves preparing regenerated cellulose fibers (B) to which additive (C) is attached. In one embodiment, step (1-2) preferably includes attaching additive (C) to at least a portion of the surface of regenerated cellulose fibers (B) using a sizing machine. Specifically, methods include: (1) attaching additive (C) to at least a portion of the surface of a fiber bundle obtained by bundling regenerated cellulose fibers (B) in the longitudinal direction using a sizing machine, followed by cutting to a predetermined length using a cutting machine; (2) attaching additive (C) to at least a portion of the surface of regenerated cellulose monofilaments using a sizing machine to obtain monofilaments to which additive (C) is attached, and then bundling a predetermined amount of the monofilaments into a fiber bundle. Method 1 allows for the production of a fiber bundle of regenerated cellulose fibers (B) to which additive (C) is attached at least a portion of the surface of the fiber bundle. Method 2 allows for the production of a fiber bundle to which additive (C) is attached at least a portion of the surface and / or at least a portion of the interfiber spaces of the fiber bundle.

[0051] In step (1-2), the amount of the additive (C) attached is adjusted so that the proportion of the additive (C) in the final resin composition is 0.01 to 0.5% by mass. In one embodiment, the amount of the additive (C) attached may be 0.02 to 16.7 parts by mass, 0.1 to 5 parts by mass, or 0.3 to 4 parts by mass per 100 parts by mass of the regenerated cellulose fibers (B).

[0052] In one embodiment, step (1-2) may be preparing regenerated cellulose fibers (B) to which additive (C) and phosphonium salt (D) are attached. When phosphonium salt (D) is attached to regenerated cellulose fibers (B), the amount of phosphonium salt (D) may be 0.002 to 1.67 parts by mass or 0.005 to 0.2 parts by mass per 100 parts by mass of regenerated cellulose fibers (B).

[0053] <Process (1-3)> Alternatively, the additive (C) may be added from a side feeder to prepare a precursor mixture or regenerated cellulose fibers without carrying out step (1-1) or step (1-2) (step (1-3)).

[0054] <Process (2)> After carrying out step (1-1) or step (1-2) (or after carrying out step (1-3)), the resin composition according to the first embodiment can be obtained (step (2)). Step (2) can include the following step (2-1) or step (2-2).

[0055] (Process (2-1)) Step (2-1) involves adding regenerated cellulose fibers (B) to the mixture obtained in step (1-1), or adding regenerated cellulose fibers (B) to which additive (C) has been attached, obtained in step (1-2), to resin (A). When step (2-1) is performed, the amount of regenerated cellulose fibers (B) added is adjusted so that the proportion of regenerated cellulose fibers (B) in the final resin composition is 3 to 60 mass%. In one embodiment, regenerated cellulose fibers (B) may be added so that the mass ratio between the mixture and regenerated cellulose fibers (B) (mixture:regenerated cellulose fibers (B)) or the mass ratio between resin (A) and regenerated cellulose fibers (B) to which additive (C) has been attached (resin (A):regenerated cellulose fibers (B) to which additive (C) has been attached) is 50:50 to 95:5.

[0056] In one embodiment, step (2-1) is preferably performed when short fibers (average fiber length of 1 to 3 mm) are used as the regenerated cellulose fibers (B) (short fiber formulation). In this case, chopped strands are preferably used as the regenerated cellulose fibers (B) added to the mixture or resin (A). In the resin composition obtained by the production method including steps (1-1) and (2-1), the average fiber length of the regenerated cellulose fibers (B) in the resin composition may be 100 to 5,000 μm, 120 to 1,500 μm, or 150 to 500 μm. When the production method according to the second embodiment uses a short fiber formulation, the components (A) to (C) may be mixed, and then kneaded and extruded in a single-screw or twin-screw extruder to obtain pellets of the resin composition.

[0057] (Process (2-2)) Step (2-2) involves impregnating a fiber bundle of regenerated cellulose fibers (B) with the mixture obtained in step (1-1) as an impregnating resin, or impregnating a fiber bundle of regenerated cellulose fibers (B) with additive (C) obtained in step (1-2) with resin (A). Step (2-2) is preferably performed when, for example, the aforementioned fiber bundle (B-1) is to be obtained as a resin composition. That is, step (2-2) involves impregnating a fiber bundle obtained by bundling regenerated cellulose fibers (B) (or regenerated cellulose fibers (B) with additive (C)) aligned in the length direction with the mixture or resin (A). As a method for impregnating with the mixture or resin (A), the methods described in the aforementioned method for producing fiber bundle (B-1) can be used.

[0058] In one embodiment, step (2-2) is preferably performed when continuous fibers of regenerated cellulose fibers (B) (long fibers) are used (long fiber formulation). In a resin composition (for example, the above-mentioned fiber bundle (B-1)) prepared by a production method including step (2-2), the average fiber length of the regenerated cellulose fibers (B) in the resin composition may be 100 to 5,000 μm or 1,000 to 4,000 μm. When the manufacturing method according to the second embodiment is a long fiber formulation, for example, regenerated cellulose fibers (B) (or regenerated cellulose fibers (B) with additive (C) attached) passed through a crosshead die are aligned in the longitudinal direction into a fiber bundle, which is then impregnated with a mixture or resin (A) to integrate them, and then cut to any desired length to obtain a resin composition as the above-mentioned fiber bundle (B-1).

[0059] [pellet] A third embodiment of the present disclosure relates to pellets containing the resin composition according to the first embodiment. The pellets according to the third embodiment can be obtained by producing the resin composition by the production method according to the second embodiment.

[0060] [Molded products and their manufacturing methods] A fourth embodiment of the present disclosure relates to a molded article containing the resin composition according to the first embodiment. The molded article according to the fourth embodiment is obtained by molding the resin composition according to the first embodiment (or the pellets according to the third embodiment). The molded article according to the fourth embodiment may be obtained by injection molding the resin composition according to the first embodiment (or the pellets according to the third embodiment). The molded article according to the fourth embodiment has less coloration and is superior in mechanical properties.

[0061] In one embodiment, when the resin composition contains short fibers, the tensile breaking strength of the molded article (measured in accordance with ISO 527) is preferably 55 MPa or more, and more preferably 60 MPa or more. The tensile strength of the molded article may be 75 MPa or more, 85 MPa or more, or even 90 MPa or more. Molded articles with such excellent mechanical properties are easily obtained with resin compositions containing 30% or more by mass of regenerated cellulose fibers (B). The inventors' investigations revealed that, for example, as shown in Comparative Example 2, when the ratio of resin (a1) to regenerated cellulose fibers (B) is 50:50, the mechanical properties may be lower than in formulations containing a lower proportion of regenerated cellulose fibers (B). On the other hand, the molded articles obtained from the resin composition according to the first embodiment did not show a decrease in mechanical properties even when the proportion of regenerated cellulose fibers (B) was increased, and furthermore, the coloration of the molded articles due to the regenerated cellulose fibers (B) was suppressed.

[0062] In one embodiment, when the resin composition is a long fiber formulation, the tensile breaking strength of the molded article (measured in accordance with ISO 527) is preferably 100 MPa or more, and more preferably 105 MPa or more.

[0063] [Application] The molded article according to the fourth embodiment has little coloring and excellent mechanical properties. Such a molded article can be suitably used for applications such as sliding members. Furthermore, when the molded article is a sliding member, it can be suitably used in applications such as AV and OA fields, measuring instruments, and transport parts.

[0064] A non-limiting list of exemplary embodiments and combinations of exemplary embodiments of the present disclosure are set forth below. [1] A resin composition, Relative to the total mass of the resin composition 40 to 97 mass% of a thermoplastic resin (A) containing a polyacetal resin (a1); 3 to 60 mass% of regenerated cellulose fiber (B); A resin composition comprising: one or more additives (C) selected from a polyamide epichlorohydrin resin, a polyamine epichlorohydrin resin, and a melamine resin in an amount of 0.01 to 0.5% by mass (provided that the total of (A) to (C) does not exceed 100% by mass). [2] The resin composition according to [1], wherein the polyacetal resin (a1) contains a copolymer. [3] The resin composition according to [1] or [2], wherein the melt flow rate (190°C, 2.16 kg load) of the polyacetal resin (a1) is more than 1 g / 10 min and not more than 60 g / 10 min. [4] The resin composition according to any one of [1] to [3], wherein the regenerated cellulose fibers (B) include solvent-process regenerated cellulose fibers. [5] A resin composition according to any one of [1] to [4], wherein the resin composition comprises a thermoplastic resin-impregnated regenerated cellulose fiber bundle (B-1) in which the regenerated cellulose fibers (B) are aligned in the longitudinal direction and impregnated with the thermoplastic resin (A) containing the additive (C). [6] The resin composition according to any one of [1] to [5], further comprising 0.001 to 0.05 mass% of a phosphonium salt (D) (provided that the total of (A) to (D) does not exceed 100 mass%). [7] A pellet comprising the resin composition according to any one of [1] to [6]. [8] A molded article comprising the resin composition according to any one of [1] to [6]. [9] The molded article according to [8], which is a sliding member.

[10] A method for producing the resin composition according to any one of [1] to [6], The method includes providing a mixture containing the thermoplastic resin (A) and the additive (C); or and preparing the regenerated cellulose fibers (B) to which the additive (C) is attached. A method for producing a resin composition.

[11] A method for producing a resin composition described in

[10] , wherein preparing the regenerated cellulose fiber (B) having the additive (C) attached thereto includes attaching the additive (C) to at least a portion of the surface of the regenerated cellulose fiber (B) using a sizing machine. [Example]

[0065] The present invention will be described in detail below with reference to examples, but the present invention is not limited to the following description.

[0066] The following materials were used as raw materials for the resin composition. <Thermoplastic resin (A)> (Resin (a1): Polyacetal resin) (a1-1): Polyacetal resin (polyacetal copolymer obtained by copolymerizing 96.7% by mass of trioxane and 3.3% by mass of 1,3-dioxolane) (melt flow rate (190°C, 2.16 kg load): 45 g / 10 min). (a1-2): Polyacetal resin (polyacetal copolymer obtained by copolymerizing 96.7% by mass of trioxane and 3.3% by mass of 1,3-dioxolane) (melt flow rate (190°C, 2.16 kg load): 9 g / 10 min). (a1-3): Polyacetal resin (polyacetal copolymer obtained by copolymerizing 96.7% by mass of trioxane and 3.3% by mass of 1,3-dioxolane) (melt flow rate (190°C, 2.16 kg load): 2.5 g / 10 min). (a1-4): Polyacetal resin (polyacetal homopolymer) (DuPont's "Delrin (registered trademark) 500P", melt flow rate (190°C, 2.16 kg load): 15 g / 10 min).

[0067] (Resin (a2): Other thermoplastic resins) (a2-1): Propylene homopolymer (PP homopolymer, manufactured by SunAllomer Co., Ltd., product name "PMB02A", melt flow rate (230°C, 2.16 kg load): 70 g / 10 min). (a2-2): Maleic anhydride-modified polypropylene resin (SK Functional Polymer, product name "OREVAC (registered trademark) CA100", melt flow rate (190°C, 2.16 kg load): 10 g / 10 min).

[0068] <Regenerated cellulose fiber (B)> (B1): Chopped strands of solvent-process regenerated cellulose fiber (manufactured by Lenzing, product name "Lyocell (registered trademark) dull", fiber length: 2 mm, average fiber diameter (major diameter): 13 μm). (B2): Continuous fiber of solvent-process regenerated cellulose fiber (manufactured by Biomid Fiber, product name "BioMid Fiber (registered trademark)", average fiber diameter (long diameter): 11 μm).

[0069] <Additive (C)> (C1): Polyamide epichlorohydrin resin aqueous solution (manufactured by Taoka Chemical Co., Ltd., product name "Sumirez Resin SLX-1", solid content 25%). (C2): Polyamide polyamine epichlorohydrin resin aqueous solution (manufactured by Arakawa Chemical Industries, Ltd., product name "Arafix 2550P", solid content 25%). (C3): Polyamine epichlorohydrin resin aqueous solution (manufactured by Hoshikawa PMC Corporation, product name "WS4011", solid content 20%). (C4): Melamine resin aqueous solution (manufactured by Taoka Chemical Co., Ltd., product name "Sumirez Resin 8%AC", solid content 8%).

[0070] <Phosphonium Salt (D)> (D1): Methyltriphenylphosphonium bromide (Tokyo Chemical Industry Co., Ltd.).

[0071] <Other ingredients (E)> (E1): Urethane resin aqueous solution (manufactured by Meisei Chemical Industry Co., Ltd., product name "Pascol (registered trademark) NJ-1", solid content 30%). (E2): Aqueous solution of blocked isocyanate (manufactured by Meisei Chemical Industry Co., Ltd., product name "DM6400", solid content 42%). (E3): Methyl acrylate-maleic acid copolymer (manufactured by Ashland, product name "Gantrez (registered trademark) AN-119", solid content 100%).

[0072] [Example 1] Steps (1-2) and (2-1) were carried out to prepare the resin composition of Example 1. Specifically, regenerated cellulose fibers (B1), pure water in an amount 10 times the amount of the regenerated cellulose fibers (B1), and additive (C1) were placed in a container and stirred at 300 rpm for 30 minutes using a three-blade stirrer. The mixture was then heated to 80°C to evaporate the water, and then dried at 120°C for 7 hours to adhere additive (C1) to the surface of the regenerated cellulose fibers (B1). The amount of additive (C1) adhered to 100 parts by mass of regenerated cellulose fibers (B1) was 1 part by mass (solid content). The regenerated cellulose fibers (B1) with additive (C1) attached and resin (a1-1) were then fed into a 30 mm diameter twin-screw extruder (TEX30α, manufactured by The Japan Steel Works, Ltd.), and the cylinder temperatures at the raw material feed section and die tip were set to 200°C, with the intermediate temperature set to 180-200°C. The extrusion rate was 20 kg / h and the screw rotation speed was 200 rpm. The mixture was then cut into 5 mm lengths using a pelletizer to obtain resin compositions (pellets) with the composition shown in Table 1. The percentage of additive (C) in Table 1 is the solid content.

[0073] Next, the resin composition (pellets) of Example 1 was injection molded under the following conditions to obtain a molded article (ISO tensile test piece). The obtained molded article was subjected to measurement of various mechanical properties and evaluation of coloration under the following conditions. (Molding conditions) Molding machine: Manufactured by Sumitomo Heavy Industries, Ltd., product name "SE100EV-A". Specimen: ISO tensile specimen. Molding temperature: 200℃. Mold temperature: 90℃.

[0074] <Evaluation of mechanical properties> Measurement of tensile breaking strength and tensile breaking strain The obtained ISO tensile test specimen was used to perform measurements in accordance with ISO 527. Specifically, a tensile tester (manufactured by Shimadzu Corporation, product name "Autograph (registered trademark) AG-20kNXDplus") was used to perform measurements under the following conditions: temperature: 23°C, test speed: 5 mm / min, and chuck distance (span): 115 mm.

[0075] <Evaluation of coloration of molded products> The L value of the obtained ISO tensile test specimen was measured using a spectrophotometer (product name "SE6000" manufactured by Nippon Denshoku Industries Co., Ltd.). The L value was compared with the L value (blank) of a test specimen obtained from a resin composition containing the same type and content of resin (A) and regenerated cellulose fiber (B) but not containing additive (C) (and phosphonium salt (D)). Test specimens with an L value 3 or more higher than the blank were deemed to pass.

[0076] [Examples 2 to 6] A resin composition was obtained in the same manner as in Example 1, except that the proportion of regenerated cellulose fiber (B1) in the resin composition was set as shown in Table 1. A molded article was prepared from the obtained resin composition in the same manner as in Example 1, and the various mechanical properties of the molded article were measured and the coloring was evaluated. The results are shown in Table 1.

[0077] [Examples 7 to 9] A resin composition was obtained in the same manner as in Example 1, except that the type of additive (C) attached to the regenerated cellulose fiber (B1) was as shown in Table 1. A molded article was prepared from the obtained resin composition in the same manner as in Example 1, and the various mechanical properties of the molded article were measured and the coloring was evaluated. The results are shown in Table 1.

[0078] [Examples 10 to 13 and Comparative Example 11] The resin compositions of each example were obtained in the same manner as in Example 1, except that the amount of additive (C1) attached to the regenerated cellulose fiber (B1) was as shown in Table 1 and the proportion of resin (a1-1) was changed according to the amount attached. Molded articles were prepared from the obtained resin compositions in the same manner as in Example 1, and the mechanical properties of the molded articles were measured and the coloring of the molded articles was evaluated. The results are shown in Tables 2 and 3.

[0079] [Example 14] The resin composition of Example 14 was prepared by carrying out steps (1-1) and (2-1). Specifically, 0.11 parts by mass (solid content) of additive (C1) was added to 100 parts by mass of resin (a1-1) to prepare a mixture. Then, regenerated cellulose fiber (B1) and the mixture were fed into a 30 mm diameter twin-screw extruder (TEX30α, manufactured by The Japan Steel Works, Ltd.). The cylinder temperature at the raw material feed section and die tip was set to 200°C, with the intermediate temperature set to 180 to 200°C. The mixture was melt-kneaded and extruded at a discharge rate of 20 kg / h and a screw rotation speed of 200 rpm. The mixture was then cut into 5 mm lengths using a pelletizer to obtain resin compositions (pellets) having the composition shown in Table 1. Molded articles were prepared from the resulting resin composition in the same manner as in Example 1, and the various mechanical properties and coloration of the molded articles were measured. The results are shown in Table 2.

[0080] [Example 15] A resin composition was obtained in the same manner as in Example 1, except that the type of resin (A) was as shown in Table 1. A molded article was prepared from the obtained resin composition in the same manner as in Example 1, and the various mechanical properties of the molded article were measured and the coloring was evaluated. The results are shown in Table 2.

[0081] [Example 16] The resin composition of Example 15 was prepared by carrying out steps (1-2) and (2-1). Specifically, 0.11 parts by mass (solid content) of additive (C1) and 0.011 parts by mass of phosphonium salt (D1) were added to 100 parts by mass of resin (a1-1) to prepare a mixture. The regenerated cellulose fiber (B1) and the mixture were then fed into a 30 mm diameter twin-screw extruder (TEX30α, manufactured by The Japan Steel Works, Ltd.). The cylinder temperature at the raw material feed section and die tip was set to 200°C, with the intermediate temperature set to 180-200°C. The mixture was melt-kneaded and extruded at a discharge rate of 20 kg / h and a screw rotation speed of 200 rpm. The mixture was then cut into 5 mm lengths using a pelletizer to obtain resin compositions (pellets) having the composition shown in Table 1. Molded articles were prepared from the resulting resin composition in the same manner as in Example 1, and the mechanical properties and coloration of the molded articles were measured. The results are shown in Table 2.

[0082] [Examples 17 to 18] A resin composition was obtained in the same manner as in Example 15, except that the amount of phosphonium salt (D1) attached was set as shown in Table 1. A molded article was prepared from the obtained resin composition in the same manner as in Example 1, and the various mechanical properties of the molded article were measured and the coloring was evaluated. The results are shown in Table 2.

[0083] [Comparative Examples 1 to 6] The regenerated cellulose fiber (B1) and resin (a1-1) were fed into a 30 mm diameter twin-screw extruder (TEX30α, manufactured by The Japan Steel Works, Ltd.), and the cylinder temperature at the raw material supply section and die tip was set to 200°C, with the temperature in between set to 180 to 200°C. The mixture was melt-kneaded and extruded at a discharge rate of 20 kg / h and a screw rotation speed of 200 rpm. The mixture was then cut into 5 mm lengths using a pelletizer to obtain resin compositions (pellets) having the composition shown in Table 1. Molded articles were prepared from the resulting resin compositions in the same manner as in Example 1, and the various mechanical properties of the molded articles were measured and the coloration was evaluated. The results are shown in Table 3.

[0084] Comparative Example 7 A resin composition was obtained in the same manner as in Comparative Example 1, except that the type of resin (A) was as shown in Table 1. A molded article was prepared from the obtained resin composition in the same manner as in Example 1, and the various mechanical properties of the molded article were measured and the coloring was evaluated. The results are shown in Table 3.

[0085] [Comparative Examples 8 to 10] Resin compositions of each example were obtained in the same manner as in Example 1, except that instead of additive (C1), other components (E1) to (E3) were attached to regenerated cellulose fiber (B1). Molded articles were prepared from the obtained resin compositions in the same manner as in Example 1, and the various mechanical properties of the molded articles were measured and the coloring of the molded articles was evaluated. The results are shown in Table 3.

[0086] [Examples 19 to 24 and Comparative Examples 12 to 13] Resin compositions of each example were obtained in the same manner as in Example 1, except that the types of resin (A) and additive (C) were as shown in Table 1. Molded articles were prepared from the obtained resin compositions in the same manner as in Example 1, and the various mechanical properties of the molded articles were measured and the coloring was evaluated. The results are shown in Table 4.

[0087] [Comparative Examples 14 and 16] Resin compositions of each example were obtained in the same manner as in Comparative Example 1, except that the type of resin (A) was as shown in Table 1. Molded articles were prepared from the obtained resin compositions in the same manner as in Example 1, and the various mechanical properties of the molded articles were measured and the coloring was evaluated. The results are shown in Table 4.

[0088] [Comparative Examples 15 and 17] Resin compositions of each example were obtained in the same manner as in Example 1, except that the type of resin (A) was as shown in Table 1. Molded articles were prepared from the obtained resin compositions in the same manner as in Example 1, and the mechanical properties of the molded articles were measured and the coloring was evaluated. The results are shown in Table 4.

[0089] [Example 25] 74.75% by mass of resin (a1-1) and 0.25% by mass of additive (C1) were mixed and charged into a twin-screw extruder. The mixture was melt-kneaded at a cylinder temperature of 220°C and the resulting molten mixture was impregnated into a fiber bundle of regenerated cellulose fibers (B2) aligned in the longitudinal direction through a crosshead die so that the regenerated cellulose fibers (B2) were 25% by mass. The fiber bundle was then shaped using a shaping nozzle at the crosshead die outlet, shaped using a shaping roll, and cut into 7 mm lengths using a pelletizer to obtain the resin composition of Example 24 consisting of pelletized fiber bundles (B-1). Molded articles were prepared from the resulting resin composition in the same manner as in Example 1, and various mechanical properties and color evaluations of the molded articles were performed. The results are shown in Table 5.

[0090] [Examples 26 and 27 and Comparative Example 18] Resin compositions of each example were obtained in the same manner as in Example 25, except that the contents of resin (A) and additive (C1) were as shown in Table 3. Molded articles were prepared from the obtained resin compositions in the same manner as in Example 1, and the mechanical properties of the molded articles were measured and the coloring was evaluated. The results are shown in Table 5.

[0091] [Example 28] A resin composition was obtained in the same manner as in Example 25, except that 74.74% by mass of resin (a1-1), 0.25% by mass of additive (C1), and 0.01% by mass of phosphonium salt (D1) were mixed. A molded article was prepared from the obtained resin composition in the same manner as in Example 1, and various mechanical properties of the molded article were measured and the coloring of the molded article was evaluated. The results are shown in Table 5.

[0092] [Table 1]

[0093] [Table 2]

[0094] [Table 3]

[0095] [Table 4]

[0096] [Table 5]

[0097] As shown in Tables 1 to 5, the molded articles of Examples 1 to 28 obtained from the resin composition according to the first embodiment were less discolored and had excellent mechanical properties. On the other hand, the molded articles obtained from the resin compositions of Comparative Examples 1 to 10, 12 to 13, and 18, which did not contain additive (C), were more discolored and had poorer mechanical properties than the molded articles of the Examples. In Comparative Example 11, in which the proportion of additive (C) was outside the range of the first embodiment, the coloration of the molded article was suppressed, but the mechanical properties were poor. These results confirmed that by combining resin (a1) and regenerated cellulose fiber (B), molded articles with excellent fluidity and mechanical properties during injection molding and less discoloration could be obtained. Furthermore, for example, the resin composition of Example 1 had better mechanical properties than the resin compositions of Comparative Examples 15 and 17, which contained polypropylene as resin (A). Furthermore, as shown in Table 5, even in the long fiber formulation, molded articles obtained from the resin composition according to the first embodiment were less discolored and had good mechanical properties. From the above results, it was found that the resin composition according to the first embodiment can provide a molded article that is less colored and has excellent mechanical properties.

Claims

1. A resin composition comprising: Relative to the total mass of the resin composition 40 to 97% by mass of a thermoplastic resin (A) containing a polyacetal resin (a1); 3 to 60% by mass of regenerated cellulose fibers (B); and 0.01 to 0.5 mass% of one or more additives (C) selected from a polyamide epichlorohydrin resin, a polyamine epichlorohydrin resin, and a melamine resin (provided that the total of (A) to (C) does not exceed 100 mass%).

2. The resin composition according to claim 1 , wherein the polyacetal resin (a1) comprises a copolymer.

3. The resin composition according to claim 1 or 2, wherein the polyacetal resin (a1) has a melt flow rate (190°C, 2.16 kg load) of more than 1 g / 10 min and not more than 60 g / 10 min.

4. The resin composition according to claim 1 or 2, wherein the regenerated cellulose fibers (B) include solvent-process regenerated cellulose fibers.

5. The resin composition according to claim 1 or 2, comprising a thermoplastic resin-impregnated regenerated cellulose fiber bundle (B-1) in which the regenerated cellulose fiber (B) is aligned in the longitudinal direction and impregnated with the thermoplastic resin (A) containing the additive (C).

6. The resin composition according to claim 1 or 2, further comprising 0.001 to 0.05 mass% of a phosphonium salt (D) (provided that the total of (A) to (D) does not exceed 100 mass%).

7. A pellet comprising the resin composition according to claim 1 or 2.

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

9. The molded article according to claim 8, which is a sliding member.

10. A method for producing the resin composition according to claim 1 or 2, The method includes preparing a mixture containing the thermoplastic resin (A) and the additive (C); or A method for producing a resin composition, comprising: preparing the regenerated cellulose fibers (B) having the additive (C) attached thereto.

11. A method for producing a resin composition as described in claim 10, wherein preparing the regenerated cellulose fibers (B) includes attaching the additive (C) to at least a portion of the surface of the regenerated cellulose fibers (B) using a sizing machine.

Images