Thermoplastic resin composition

Abstract

The present invention relates to a thermoplastic resin composition containing a thermoplastic resin (A) and a cellulose-based fiber (B) having an average fiber length of 2-1,000 μm, wherein, in a type A1 specimen prepared from the thermoplastic resin composition according to ISO 294-1, the number of agglomerates of the cellulose-based fiber (B) that exceed 100 μm × 100 μm is at most 2 per 30 mm2. The thermoplastic resin composition has excellent tensile fracture strain. In addition, the thermoplastic resin composition can contribute to achieving Goals 9, 13, etc. of Sustainable Development Goals (SDGs) in terms of contributing to a reduction in resource consumption by making a molded product therefrom lightweight.

Description

thermoplastic resin composition

[0001] The present invention relates to a thermoplastic resin composition.

[0002] Resin compositions containing thermoplastic resins and cellulosic fibers have the advantage of being lightweight, and therefore are used in the fields of automobile parts, aircraft interior parts, household appliances, construction materials, etc., in place of metal materials.

[0003] Patent Document 1 discloses a resin molding obtained by molding a cellulose fiber-dispersed resin composite material obtained by dispersing cellulose fibers in a thermoplastic resin, in which the cellulose fiber-dispersed resin composite material contains aggregates of the cellulose fibers, and at least a portion of the aggregates has a size of 2.0 × 10 in plan view. ４ ~2.0 x 10 ５ μm ２ A resin molded body that is an aggregate having an area of ​​1000 nm is disclosed.

[0004] Patent Document 2 describes a fiber-reinforced polyamide resin composition containing polyamide 6 and acetylated microfibrillated cellulose fibers, in which the relative viscosity of the polyamide 6 is 2.3 or more and the carboxyl terminal group concentration of the polyamide 6 is 7.0 × 10 －５ eq / g or less, and the polyamide resin composition is obtained by melt-kneading the polyamide 6, acetylated microfibrillated cellulose-based fibers, and an amide compound.

[0005] JP 2020-193262 A JP 2021-036024 A

[0006] However, the resin molding containing cellulose fiber aggregates having a predetermined area disclosed in Patent Document 1 has a problem of poor tensile breaking strain. Also, there has been a demand for a fiber-reinforced polyamide resin composition such as that disclosed in Patent Document 2 to have a further improved tensile breaking strain.

[0007] Therefore, an object of the present invention is to provide a thermoplastic resin composition having excellent tensile strain at break.

[0008] The present invention relates to the following: [1] A thermoplastic resin composition comprising a thermoplastic resin (A) and a cellulose-based fiber (B) having an average fiber length of 2 to 1,000 μm, wherein, in a Type A1 test piece prepared from the thermoplastic resin composition in accordance with ISO 294-1, agglomerates of the cellulose-based fiber (B) exceeding 100 μm x 100 μm are present in an area of ​​30 mm or less. ２ [2] The thermoplastic resin composition according to [1], wherein the average fiber diameter of the cellulose-based fiber (B) is 1 μm to 45 μm. [3] The thermoplastic resin composition according to [1] or [2], wherein the ratio of the average fiber length to the average fiber diameter (L / D) of the cellulose-based fiber (B) is 2 to 30. [4] The thermoplastic resin composition according to any one of [1] to [3], wherein the cellulose-based fiber (B) is an unmodified cellulose-based fiber. [5] The thermoplastic resin composition according to any one of [1] to [4], wherein the content of the cellulose-based fiber (B) is 1% by mass to 35% by mass, relative to 100% by mass of the thermoplastic resin composition. [6] The thermoplastic resin composition according to any one of [1] to [5], wherein the thermoplastic resin (A) is at least one selected from the group consisting of polyamide resins, polyolefin resins, halogenated polyolefin resins, polystyrene resins, polyvinyl carboxylate resins, polyurethane resins, acrylonitrile-alkadiene-styrene resins, acrylic resins, polyether resins, polycarbonate resins, polyester resins, polyamide elastomers, and composite resins containing any of these as constituent components. [7] A molded article comprising the thermoplastic resin composition according to any one of [1] to [6]. [8] The molded article according to [7], which is a member for transportation equipment, electrical appliances, or building materials.

[0009] According to the present invention, it is possible to provide a thermoplastic resin composition having excellent tensile strain at break.

[0010] [Definition of Terms] "Thermoplastic resin (A)" is also referred to as "component (A)." The same applies to "cellulosic fiber (B)," etc. In this specification, when a composition contains multiple substances corresponding to each component, the content of each component in the composition means the total amount of the multiple substances present in the composition, unless otherwise specified. In this specification, the symbol "to" indicating a numerical range means that the numerical values ​​before and after it are included as the lower and upper limits.

[0011] [Thermoplastic resin composition] The thermoplastic resin composition contains a thermoplastic resin (A) and a cellulose-based fiber (B) having an average fiber length of 2 to 1,000 μm. In addition, in a type A1 test piece prepared from the thermoplastic resin composition in accordance with ISO 294-1, the number of aggregates of the cellulose-based fiber (B) exceeding 100 μm × 100 μm is 30 mm. ２ There are two or less per prize.

[0012] The thermoplastic resin composition tends to have excellent tensile strain at break and also excellent mechanical properties such as tensile strength, flexural strength, flexural modulus, etc. Furthermore, the thermoplastic resin composition tends to have excellent tensile strain at break and also improve or maintain impact strength.

[0013] [Thermoplastic Resin (A)] The thermoplastic resin (A) is not particularly limited, and examples thereof include polyamide resins, polyolefin resins, halogenated polyolefin resins, polystyrene resins, polyvinyl carboxylate resins, polyurethane resins, acrylonitrile-alkadiene-styrene resins, acrylic resins, polyether resins, polycarbonate resins, polyester resins, polyamide elastomers, and composite resins containing these as constituent components.

[0014] <Polyamide Resin> Examples of polyamide resins include aliphatic polyamide resins (A-1) that do not have an aromatic ring, and aromatic polyamide resins (A-2) that contain an aromatic ring. Examples of the aliphatic polyamide resins (A-1) include aliphatic homopolyamide resins (A-1-1) and aliphatic copolymer polyamide resins (A-1-2). Examples of the aromatic polyamide resins (A-2) include aromatic homopolyamide resins (A-2-1) and aromatic copolymer polyamide resins (A-2-2).

[0015] Aliphatic homopolyamide resin (A-1-1) refers to a polyamide resin containing one type of monomer component. Examples of the monomer component constituting the aliphatic polyamide resin include a combination of an aliphatic diamine and an aliphatic dicarboxylic acid, a lactam, or an aminocarboxylic acid. When the monomer component constituting the aliphatic polyamide resin is a combination of an aliphatic diamine and an aliphatic dicarboxylic acid, the combination of one type of aliphatic diamine and one type of aliphatic dicarboxylic acid is considered to be one type of monomer component.

[0016] The aliphatic diamine preferably has 2 to 20 carbon atoms, and more preferably has 4 to 12 carbon atoms. The aliphatic dicarboxylic acid preferably has 2 to 20 carbon atoms, and more preferably has 6 to 12 carbon atoms. The lactam preferably has 5 to 12 carbon atoms. The aminocarboxylic acid preferably has 5 to 12 carbon atoms.

[0017] Examples of aliphatic diamines include ethylenediamine, tetramethylenediamine, pentamethylenediamine, hexamethylenediamine, heptamethylenediamine, octamethylenediamine, nonamethylenediamine, decamethylenediamine, undecamethylenediamine, dodecamethylenediamine, tridecanediamine, tetradecanediamine, pentadecanediamine, hexadecanediamine, heptadecanediamine, octadecanediamine, nonadecanediamine, and eicosanediamine. Examples of aliphatic dicarboxylic acids include oxalic acid, malonic acid, succinic acid, glutaric acid, adipic acid, pimelic acid, suberic acid, azelaic acid, sebacic acid, undecanedionic acid, dodecanedionic acid, tridecanedionic acid, tetradecanedionic acid, pentadecanedioic acid, hexadecanedioic acid, octadecanedioic acid, and eicosanedionic acid.

[0018] Examples of the combination of an aliphatic diamine and an aliphatic dicarboxylic acid include a combination of hexamethylenediamine and adipic acid, a combination of hexamethylenediamine and sebacic acid, and a combination of hexamethylenediamine and dodecanedioic acid. The combination of an aliphatic diamine and an aliphatic dicarboxylic acid is preferably an equimolar salt of the combination.

[0019] Examples of lactams include γ-butyrolactam, δ-valerolactam, ε-caprolactam, enantholactam, undecanelactam, and dodecanelactam. Examples of aminocarboxylic acids include 5-aminopentanoic acid, 6-aminohexanoic acid, 7-aminoheptanoic acid, 9-aminononanoic acid, 11-aminoundecanoic acid, and 12-aminododecanoic acid. From the viewpoint of productivity, the lactam is preferably ε-caprolactam, undecanelactam, or dodecanelactam.

[0020] Specific examples of the aliphatic homopolyamide resin (A-1-1) include polybutyrolactam (polyamide 4), polyvalerolactam (polyamide 5), polycaprolactam (polyamide 6), polyenantholactam (polyamide 7), polyundecane lactam (polyamide 11), polylauryllactam (polyamide 12), polytetramethylene adipamide (polyamide 46), polytetramethylene azelamide (polyamide 49), polytetramethylene sebacamide (polyamide 410), and polytetramethylene dodecamide (polyamide 412). Polypentamethylene adipamide (polyamide 56), polypentamethylene azelamide (polyamide 59), polypentamethylene sebacamide (polyamide 510), polypentamethylene dodecamide (polyamide 512), polyhexamethylene adipamide (polyamide 66), polyhexamethylene azelamide (polyamide 69), polyhexamethylene sebacamide (polyamide 610), polyhexamethylene dodecamide (polyamide 612), polynonameethylene adipamide (polyamide 96), polynonameethylene azelamide (polyamide 99), polynonameethylene sebacamide (polyamide polyamide 910), polynonamethylene dodecamide (polyamide 912), polydecamethylene adipamide (polyamide 106), polydecamethylene azelamide (polyamide 109), polydecamethylene decamide (polyamide 1010), polydecamethylene dodecamide (polyamide 1012), polydodecamethylene adipamide (polyamide 126), polydodecamethylene azelamide (polyamide 129), polydodecamethylene sebacamide (polyamide 1210), polydodecamethylene dodecamide (polyamide 1212), polydodecamethylene oxamide (polyamide 122), and the like.

[0021] <<Aliphatic Copolymer Polyamide Resin (A-1-2)>> The aliphatic copolymer polyamide resin (A-1-2) is an aliphatic polyamide resin that contains two or more types of monomer components constituting the aliphatic polyamide resin and does not have an aromatic ring. Thus, examples of the aliphatic copolymer polyamide resin (A-1-2) include a combination of an aliphatic diamine and an aliphatic dicarboxylic acid, and an aliphatic copolymer polyamide resin that is a copolymer of two or more types of monomers selected from the group consisting of lactam and aminocarboxylic acid.

[0022] Specific examples of the aliphatic copolymer polyamide resin (A-1-2) include caprolactam / hexamethylenediaminoadipic acid copolymer (polyamide 6 / 66), caprolactam / hexamethylenediaminoazelaic acid copolymer (polyamide 6 / 69), caprolactam / hexamethylenediaminosebacic acid copolymer (polyamide 6 / 610), caprolactam / hexamethylenediaminoundecanoic acid copolymer (polyamide 6 / 611), caprolactam / hexamethylenediaminododecanoic acid copolymer (polyamide 6 / 612), caprolactam / aminoundecanoic acid copolymer (polyamide 6 / 6 / 11), caprolactam / lauryllactam copolymer (polyamide 6 / 12), caprolactam / hexamethylenediaminoadipic acid / lauryllactam copolymer (polyamide 6 / 66 / 12), caprolactam / hexamethylenediaminoadipic acid / hexamethylenediaminosebacic acid copolymer (polyamide 6 / 66 / 610), caprolactam / hexamethylenediaminoadipic acid / hexamethylenediaminododecanedicarboxylic acid copolymer (polyamide 6 / 66 / 612), hexamethylenediaminoadipic acid / caprolactam copolymer (polyamide 66 / 6), etc.

[0023] <Aromatic Homopolyamide Resin (A-2-1)> The aromatic homopolyamide resin (A-2-1) refers to a polyamide resin containing one type of monomer component constituting the aliphatic polyamide resin. Thus, examples of the aromatic homopolyamide resin (A-2-1) include a combination of an aliphatic and / or alicyclic diamine with an aromatic dicarboxylic acid, a combination of an aromatic diamine with an aliphatic and / or alicyclic dicarboxylic acid, and a combination of an aromatic diamine with an aromatic dicarboxylic acid. Examples of the aliphatic diamine and the aliphatic dicarboxylic acid include those described above.

[0024] Examples of aromatic dicarboxylic acids include terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, 1,4-phenylenedioxydiacetic acid, 1,3-phenylenedioxydiacetic acid, dibenzoic acid, 4,4'-oxydibenzoic acid, diphenylmethane-4,4'-dicarboxylic acid, diphenylsulfone-4,4'-dicarboxylic acid, and 4,4'-biphenyldicarboxylic acid. Examples of alicyclic dicarboxylic acids include 1,3-cyclopentanedicarboxylic acid and 1,4-cyclohexanedicarboxylic acid.

[0025] Examples of aromatic diamines include p-phenylenediamine, m-phenylenediamine, p-xylenediamine, m-xylenediamine, 4,4'-diaminodiphenylmethane, 4,4'-diaminodiphenylsulfone, 4,4'-diaminodiphenylether, etc. Examples of alicyclic diamines include cyclohexanediamine, methylcyclohexanediamine, isophoronediamine, etc.

[0026] Specific examples of the aromatic homopolyamide resin (A-2-1) include polynonamethylene terephthalamide (polyamide 9T), polydecamethylene terephthalamide (polyamide 10T), polymetaxylylene adipamide (polyamide MXD6), and polymetaxylylene azelamide (polyamide MXD9).

[0027] <Aromatic Copolymer Polyamide Resin (A-2-2)> The aromatic copolymer polyamide resin (A-2-2) is an aromatic polyamide resin comprising two or more monomer components. Examples of the aromatic copolymer polyamide resin (A-2-2) include aromatic polyamide resins that are copolymers of monomers selected from a combination of an aliphatic and / or alicyclic diamine and an aromatic dicarboxylic acid, a combination of an aromatic diamine and an aliphatic and / or alicyclic dicarboxylic acid, and a combination of an aromatic diamine and an aromatic dicarboxylic acid. When the monomer components constituting the aromatic polyamide resin are a combination of a diamine and a dicarboxylic acid, a combination of one diamine and one dicarboxylic acid is considered to be one monomer component. Examples of the aliphatic diamine, alicyclic diamine, aromatic diamine, aliphatic dicarboxylic acid, alicyclic dicarboxylic acid, and aromatic dicarboxylic acid are those described above.

[0028] Specific examples of the aromatic copolymer polyamide resin (A-2-2) include poly(tetramethylene terephthalamide / hexamethylene terephthalamide) copolymer (polyamide 4T / 6T), poly(tetramethylene terephthalamide / tetramethylene adipamide) copolymer (polyamide 4T / 46), poly(hexamethylene terephthalamide / hexamethylene isophthalamide) copolymer (polyamide 6T / 6I), and the like.

[0029] <Polyolefin Resin> Examples of polyolefin resins include high-density polyethylene (HDPE), medium-density polyethylene (MDPE), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), ultra-high molecular weight polyethylene (UHMWPE), polypropylene (PP), polybutene (PB), polymethylpentene (TPX), etc. The polyolefin resin may be modified with a functional group such as a carboxyl group and its salt, an acid anhydride group, or an epoxy group.

[0030] <Halogenated Polyolefin Resin> Examples of halogenated polyolefin resins include resins in which at least some of the hydrogen atoms of the polyolefin resins have been replaced with halogen atoms, such as fluorine, chlorine, bromine, and iodine.

[0031] Preferably, halogenated polyolefin resin is fluorinated polyolefin resin.As fluorinated polyolefin resin, can be enumerated polyvinylidene fluoride (PVDF), polyvinyl fluoride (PVF), polytetrafluoroethylene (PTFE), polychlorofluoroethylene (PCTFE), tetrafluoroethylene / ethylene copolymer (ETFE), ethylene / chlorotrifluoroethylene copolymer (ECTFE), tetrafluoroethylene / hexafluoropropylene copolymer (FEP), tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride copolymer (THV), tetrafluoroethylene / hexafluoropropylene / vinylidene fluoride / perfluoro(alkyl vinyl ether) copolymer, tetrafluoroethylene / perfluoro(alkyl vinyl ether) copolymer (PFA), tetrafluoroethylene / hexafluoropropylene / perfluoro(alkyl vinyl ether) copolymer, chlorotrifluoroethylene / perfluoro(alkyl vinyl ether) / tetrafluoroethylene copolymer (CPT) etc.

[0032] <Polyvinyl Carboxylate Resin> Examples of polyvinyl carboxylate resins include those obtained by polymerizing a vinyl carboxylate compound using a conventionally known polymerization method. Here, the polymerization initiator can be appropriately selected depending on the polymerization method. Examples of such vinyl carboxylate compounds include vinyl acetate, n-propenyl acetate, isopropenyl acetate, n-butenyl acetate, isobutenyl acetate, vinyl propionate, vinyl butanoate, vinyl pentanoate, vinyl hexanoate, vinyl octanoate, vinyl decanoate, vinyl dodecanoate, and vinyl hexadecanoate. Specific examples of polyvinyl carboxylate resins include polyvinyl acetate.

[0033] <Polyurethane Resin> Examples of polyurethane resins include polyurethane (PU) and polyurethane elastomers. Polyurethane resins are resins obtained by urethane reaction of a polyol component and a polyisocyanate component. Examples of polyol components include polyester polyols (condensation polyester polyols, lactone polyester polyols), polycarbonate polyols, polyether polyols, etc. Examples of polyisocyanates include aliphatic polyisocyanates, alicyclic polyisocyanates, aromatic polyisocyanates, etc. In the urethane reaction, a chain extender such as a polyhydric alcohol or a polyvalent amine can also be used.

[0034] <Acrylonitrile-Alkadiene-Styrene Resin> Examples of acrylonitrile-alkadiene-styrene resins include acrylonitrile-butadiene-styrene resins. Acrylonitrile-butadiene-styrene resins refer to resins whose main component is a copolymer composed primarily of the three components acrylonitrile, butadiene, and styrene. Examples include copolymers obtained by block or graft polymerization of a diene rubber with one or more monomers, such as an aromatic vinyl monomer and a vinyl cyanide monomer, and blends of such copolymers. The diene rubbers mentioned here include polybutadiene, polyisoprene, acrylonitrile-butadiene copolymers, styrene-butadiene copolymers, etc., and examples of aromatic vinyl monomers include styrene, α-methylstyrene, and various alkyl-substituted styrenes. Examples of vinyl cyanide monomers include acrylonitrile, methacrylonitrile, and various halogen-substituted acrylonitriles.

[0035] <Acrylic Resin> The acrylic resin includes a polymer composed of repeating units containing (meth)acrylic acid ester and / or (meth)acrylic acid. Here, (meth)acrylic acid means at least one of acrylic acid and methacrylic acid. Examples of the acrylic resin include polymethyl methacrylate (PMMA) and polyethyl methacrylate (PEMA).

[0036] <Polyether Resin> Examples of polyether resins include polyacetal resins and polyphenylene ether resins. Here, polyacetal resins are also called polyoxymethylene (POM). Examples of polyacetal resins include homopolymers of paraformaldehyde and copolymers of paraformaldehyde and oxyethylene.

[0037] <Polycarbonate Resin> Examples of polycarbonate resins include reaction products of bisphenol A or its derivatives, i.e., bisphenols, with phosgene or phenyl dicarbonate. Examples of bisphenols include 2,2'-bis(4-hydroxyphenyl)propane, 4,4'-dihydroxydiphenylalkane, 4,4'-dihydroxydiphenyl sulfone, and 4,4'-dihydroxydiphenyl ether.

[0038] <Polyester Resin> Examples of polyester resins include polybutylene terephthalate (PBT), polyethylene terephthalate (PET), polyethylene isophthalate (PEI), poly(ethylene terephthalate / ethylene isophthalate) copolymer (PET / PEI), polytrimethylene terephthalate (PTT), polycyclohexanedimethylene terephthalate (PCT), polyethylene naphthalate (PEN), polybutylene naphthalate (PBN), polyarylate (PAR), liquid crystal polyester (LCP), polylactic acid (PLA), and polyglycolic acid (PGA).

[0039] <Polyamide-based elastomer> The polyamide-based elastomer is a polyamide resin having elastomeric properties, and examples thereof include polyamide polyether, polyamide polyester, polyamide polyether polyester, etc. Examples of the polyamide-based elastomer include polyamide polyether block copolymers in which the hard segment is an aliphatic polyamide block and the soft segment is an aliphatic polyether block, and polyamide polyester block copolymers in which the hard segment is an aliphatic polyamide block and the soft segment is a non-aromatic polyester block.

[0040] <Composite Resin> A composite resin is a copolymer obtained by combining a monomer of a thermoplastic resin with a monomer of a thermoplastic resin different from the thermoplastic resin. Examples of the composite resin include polyamide polyester resin, polyamide polyether resin, polyamide polyester polyether resin, etc. Here, the polyamide polyester resin is obtained by combining a monomer having a polyamide resin as a constituent component with a monomer having a polyester resin as a constituent component. Polyamide polyether resin and polyamide polyester polyether resin can be obtained in the same manner. One or more types of thermoplastic resin (A) can be used.

[0041] <Preferred embodiment> From the viewpoint of strength and moldability, the thermoplastic resin (A) is more preferably one or more selected from the group consisting of polyamide resins, polyamide polyether resins, polyamide polyester polyether resins, and polyamide elastomers, and even more preferably a polyamide resin. Here, the polyamide resin is preferably an aliphatic polyamide resin (A-1), more preferably an aliphatic homopolyamide resin (A-1-1), even more preferably one or more selected from the group consisting of polyamide 4, polyamide 5, polyamide 6, polyamide 11, polyamide 12, polyamide 46, polyamide 56, polyamide 510, polyamide 66, polyamide 610, and polyamide 612, even more preferably one or more selected from the group consisting of polyamide 6, polyamide 12, polyamide 56, polyamide 510, polyamide 66, polyamide 610, and polyamide 612, and particularly preferably one or more selected from the group consisting of polyamide 6 and polyamide 12.

[0042] The relative viscosity of the polyamide resin is not particularly limited, but is preferably 1.5 or higher, more preferably 1.7 or higher, and even more preferably 1.9 or higher. From the viewpoint of achieving both physical properties and moldability, the relative viscosity of the polyamide resin is more preferably 1.9 to 4.2, and particularly preferably 2.3 to 3.2. The relative viscosity of the polyamide resin can be measured in accordance with JIS K 6920 under conditions of a polyamide resin concentration of 1% by weight in 96% by weight sulfuric acid at a temperature of 25°C. When the polyamide resin contains two or more polyamide resins with different relative viscosities, the relative viscosity of the polyamide resin is the value measured as described above. The relative viscosity of the polyamide resin can be adjusted by the polymerization conditions in the production of the polyamide resin.

[0043] [Cellulosic Fibers (B) Having an Average Fiber Length of 2 to 1,000 μm] Cellulosic fibers constituting the cellulosic fibers (B) having an average fiber length of 2 to 1,000 μm include unmodified cellulosic fibers and modified cellulosic fibers.

[0044] <Unmodified Cellulosic Fibers> Unmodified cellulosic fibers are fibers made of at least one polymer (hereinafter also referred to as "cellulosic polymer") selected from the group consisting of cellulose, holocellulose, and lignocellulose. Here, examples of "cellulosic polymer" include cellulose, holocellulose, and / or lignocellulose. Furthermore, unmodified cellulosic fibers are fibers in which at least some of the hydroxyl groups of the polysaccharides and lignin in the cellulosic polymers that constitute the unmodified cellulosic fibers are not substantially modified with the substituents described below. Specifically, the degree of modification (DS) of unmodified cellulosic fibers with the substituents described below is 0 to 0.01, and preferably 0.

[0045] <Modified Cellulosic Fibers> Modified cellulose fibers are fibers in which at least some of the hydroxyl groups of the polysaccharides and lignin in the cellulose polymers that make up unmodified cellulose fibers have been modified with a substituent. Here, "modified" means that the hydrogen atoms of the hydroxyl groups have been replaced with the substituent. Examples of the substituent include an acyl group, an alkyloxycarbonyl group, an alkyl group, and an alkenyl group.

[0046] The acyl group includes a group represented by the formula: R-CO- (wherein R is an alkyl group or a phenyl group).

[0047] The alkyloxycarbonyl group includes a group represented by the formula: RO-CO- (wherein R is an alkyl group or a phenyl group).

[0048] Examples of the alkyl group include unsubstituted alkyl groups having 1 to 4 carbon atoms, and alkyl groups having 1 to 4 carbon atoms substituted with a hydroxyl group or a cyano group. The alkyl group having 1 to 4 carbon atoms is linear or branched, and examples thereof include a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an n-butyl group, and a tert-butyl group.

[0049] The alkenyl group includes alkenyl groups having 2 to 4 carbon atoms, such as vinyl, allyl, and 3-butenyl groups.

[0050] The phenyl group may be an unsubstituted phenyl group or a phenyl group substituted with an alkyl group or an alkoxy group. The alkoxy group that is a substituent on the phenyl group may be an alkoxy group having 1 to 4 carbon atoms. Examples of the alkoxy group having 1 to 4 carbon atoms include a methoxy group and an ethoxy group.

[0051] Specific examples of the acyl group include an acetyl group (i.e., a methylcarbonyl group), an ethylcarbonyl group, an n-propylcarbonyl group, a pivaloyl group, a benzoyl group, a 4-methylbenzoyl group, a 4-ethylbenzoyl group, a 4-methoxybenzoyl group, and a 4-ethoxybenzoyl group.

[0052] <<Degree of Modification by Substituents>> In modified cellulosic fibers, the degree of modification by substituents of hydroxyl groups in the polysaccharides and lignin constituting the cellulose, holocellulose, and / or lignocellulose in the modified cellulosic fibers (also referred to as "DS") is not particularly limited and can be set appropriately depending on the desired properties. Here, the degree of modification by substituents refers to the degree to which hydroxyl groups present in the polysaccharide and lignin units (repeating units) constituting the cellulose, holocellulose, and / or lignocellulose in the modified cellulosic fibers have been modified by substituents.

[0053] When the cellulosic polymer is cellulose, the repeating unit is a glucopyranose residue, and the number of hydroxyl groups per unit is 3. Therefore, when the cellulosic polymer constituting the modified cellulosic fiber is composed of cellulose alone, the upper limit of the degree of modification with substituents is 3.

[0054] Lignocellulose includes cellulose, hemicellulose, and lignin. When the cellulosic polymer is hemicellulose, the repeating unit is a xylose residue in xylan or a galactose residue in arabinogalactan, and the number of hydroxyl groups per unit is two. In standard lignin, the repeating unit is a standard lignin residue, and the number of hydroxyl groups per unit is two. Therefore, when the cellulosic polymer constituting the modified cellulosic fiber is lignocellulose, the upper limit of the degree of modification with substituents is less than 3, and is usually 2.7 to 2.8, depending on the contents of hemicellulose and lignin contained in the lignocellulose.

[0055] Holocellulose includes cellulose and hemicellulose. The number of hydroxyl groups per repeating unit of cellulose and hemicellulose is 3 and 2, respectively. Therefore, when the cellulosic polymer constituting the modified cellulosic fiber is holocellulose, the upper limit of the degree of modification with substituents is less than 3.

[0056] In the modified cellulosic fibers, the degree of modification with substituents is preferably 0.4 to 2.55, more preferably 0.56 to 2.00, and particularly preferably 0.60 to 1.00.

[0057] The degree of modification (DS) by the substituents was determined by elemental analysis, neutralization titration, FT-IR, and two-dimensional NMR ( １ H and １３ The degree of acetylation can be determined by various analytical methods such as C-NMR, and is preferably determined by neutralization titration or FT-IR. For example, when the substituent is an acetyl group, the degree of acetylation in the acetylated cellulose fiber can be adjusted by adjusting the amount of the acetylating agent (i.e., acetic anhydride or acid chloride, etc.) used for acetylation, the reaction temperature, the reaction time, etc.

[0058] <Average fiber length> The average fiber length of the cellulose-based fiber (B) is 2 to 1,000 μm. When the average fiber length of the cellulose-based fiber is less than 2 μm, the mechanical properties tend to be poor. When the average fiber length of the cellulose-based fiber (B) is more than 1,000 μm, the aggregates of the cellulose-based fiber (B) tend to be 30 mm or less. ２ More than two fibers per 1000 μm. Furthermore, if the average fiber length of the cellulose-based fiber (B) exceeds 1,000 μm, the tensile strain at break is poor. The upper limit of the average fiber length of the cellulose-based fiber (B) is 1,000 μm, preferably 500 μm, more preferably 350 μm, and even more preferably 250 μm. The lower limit of the average fiber length of the cellulose-based fiber (B) is 2 μm, preferably 3 μm, more preferably 10 μm, even more preferably 40 μm, and even more preferably 200 μm. Therefore, the specific range of the average fiber length of the cellulose-based fiber (B) is preferably 3 μm to 1,000 μm, more preferably 40 μm to 1,000 μm, and particularly preferably 200 to 350 μm. The fiber length of the cellulose-based fiber (B) is measured by observing the fiber using an optical microscope or a digital microscope, and measuring the longitudinal length of the cellulose fiber from the obtained image. The lengths of 100 randomly selected fibers are measured, and the average value is taken as the average fiber length.

[0059] <Average Fiber Diameter> The average fiber diameter of the cellulose-based fiber (B) is preferably 1 μm to 45 μm. When the average fiber diameter of the cellulose-based fiber (B) is within this range, the mechanical properties tend to be good. The upper limit of the average fiber diameter of the cellulose-based fiber (B) is preferably 45 μm, more preferably 30 μm, and particularly preferably 25 μm. The lower limit of the average fiber diameter of the cellulose-based fiber (B) is preferably 1 μm, more preferably 2 μm, even more preferably 5 μm, even more preferably 10 μm, and particularly preferably 15 μm. Therefore, the specific range of the average fiber diameter of the cellulose-based fiber (B) is more preferably 5 μm to 45 μm, even more preferably 10 to 30 μm, and particularly preferably 15 to 25 μm. The fiber diameter of the cellulose-based fiber (B) is observed in the same manner as for the fiber length, and the length perpendicular to the longitudinal direction of the cellulose fiber is measured from the obtained image. The diameters of a total of 100 randomly selected fibers are measured, and the average value is taken as the average fiber diameter.

[0060] <Ratio of Average Fiber Length to Average Fiber Diameter (L / D)> The ratio (L / D) of the average fiber length (L) to the average fiber diameter (D) of the cellulose-based fiber (B) is preferably 2 to 30. When the L / D of the cellulose-based fiber (B) is within the above range, the mechanical properties tend to be good. The L / D of the cellulose-based fiber (B) is more preferably 3 to 25, even more preferably 5 to 25, and particularly preferably 8 to 20.

[0061] <Bulk Density> The bulk density of the cellulose-based fiber (B) is preferably 0.02 g / mL to 0.50 g / mL, more preferably 0.04 g / mL to 0.40 g / mL, and particularly preferably 0.06 g / mL to 0.20 g / mL. When the bulk density of the cellulose-based fiber (B) is within this range, the cellulose-based fiber (B) tends to be more uniformly dispersed in the thermoplastic resin composition and less prone to breakage or destruction. Furthermore, when the bulk density of the cellulose-based fiber (B) is within this range, the mechanical properties of the molded article formed from the thermoplastic resin composition tend to be improved. The bulk density of the cellulose fiber can be measured by the method described in the Examples.

[0062] <Preferred embodiment> The cellulosic fiber (B) is preferably an unmodified cellulosic fiber from the viewpoints of economy, environmental load, simplification of production, and the like.

[0063] [Method for producing cellulose-based fiber (B)] The method for producing cellulose-based fiber (B) is not particularly limited and can be appropriately set depending on the desired form of cellulose-based fiber (B). When the cellulose-based fiber (B) is an unmodified cellulose-based fiber, an example of the method for producing the cellulose-based fiber (B) is the method for producing the cellulose-based fiber (B) (1) described below. When the cellulose-based fiber (B) is a modified cellulose-based fiber, an example of the method for producing the cellulose-based fiber (B) is the method for producing the cellulose-based fiber (B) (2) described below.

[0064] <Method (1) for producing cellulosic fiber (B)> The method (1) for producing cellulosic fiber (B) is a method for producing unmodified cellulosic fiber. The method for producing unmodified cellulosic fiber includes a step of defibrating an unmodified cellulosic fiber-containing material to obtain unmodified cellulosic fiber.

[0065] <<Unmodified Cellulosic Fiber-Containing Material>> The unmodified cellulosic fiber-containing material is a raw material for the cellulosic fibers (B). The unmodified cellulosic fiber-containing material is preferably cellulosic pulp (an aggregate of unmodified cellulosic fibers).

[0066] Cellulosic pulp refers to a fiber aggregate composed of cellulose polymers separated from plant materials. Examples of plants include wood, bamboo, hemp, jute, kenaf, cotton, beet, agricultural waste, etc. Examples of wood include wood derived from conifers or broad-leaved trees such as Sitka spruce, pine (e.g., Abies sachalinensis and red pine), cedar, cypress, eucalyptus, and acacia.

[0067] Cellulosic pulp includes pulp that does not contain lignin (such as pulp made of cellulose or holocellulose) and pulp that contains lignin (lignopulp). Here, lignopulp includes pulp containing trace amounts of lignin, as long as lignin is detectable. The amount of lignin in lignopulp can be quantified by the Klason method. The lignin content of lignopulp is not particularly limited, but is preferably 0.1 to 40% by mass, more preferably 0.1 to 35% by mass, and particularly preferably 0.1 to 30% by mass.

[0068] The cellulosic pulp is preferably pulp obtained from cotton (cotton pulp) or pulp obtained from wood (wood pulp), and more preferably pulp obtained from cotton (cotton pulp).The wood pulp is preferably pulp derived from broad-leaved trees (hardwood pulp).

[0069] Cellulosic pulp can be obtained by treating the above-mentioned plant-derived raw materials by mechanical pulping, chemical pulping, or a combination of mechanical and chemical pulping. Pulps obtained in this manner include kraft pulp (KP), mechanical pulp (MP), etc. Kraft pulp (KP) includes unbleached softwood kraft pulp (NUKP), oxygen-bleached softwood kraft pulp (NOKP), and bleached softwood kraft pulp (NBKP). Mechanical pulp (MP) includes groundwood pulp (GP), refiner GP (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), etc.

[0070] The average fiber diameter of the cellulosic fiber-containing material is not particularly limited, but is preferably 10 to 500 μm. With such an average fiber diameter, defibration (microfibrillation) can be carried out efficiently.

[0071] <<Average fiber diameter>> The average fiber diameter of the unmodified cellulosic fiber-containing material is not particularly limited, but is preferably 10 to 500 μm. With such an average fiber diameter, the unmodified cellulosic fiber-containing material can be efficiently defibrated.

[0072] <<Defibrillation Method>> Examples of a method for defibrillating an unmodified cellulosic fiber-containing material include known defibrillation methods for defibrillating pulp. Specific examples of the defibrillation method include a method of mechanically grinding or beating an aqueous suspension or slurry of unmodified cellulosic pulp using a refiner, high-pressure homogenizer, grinder, single-screw kneader, multi-screw kneader (preferably a twin-screw kneader), bead mill, or the like. These defibrillation methods may be used in combination.

[0073] Furthermore, by melt-kneading the unmodified cellulose fiber-containing material and the thermoplastic resin (A) together, the unmodified cellulose fiber-containing material can be defibrated during the melt-kneading to form cellulose fibers (B), which are unmodified cellulose fibers, in the thermoplastic resin (A). This allows for efficient defibration of the unmodified cellulose fiber-containing material and production of the thermoplastic resin composition.

[0074] <Method (2) for producing cellulose-based fiber (B)> The method (2) for producing cellulose-based fiber (B) is a method for producing modified cellulose-based fiber. The method for producing modified cellulose-based fiber includes a step of modifying unmodified cellulose-based fiber to obtain the modified cellulose-based fiber. Alternatively, the method for producing modified cellulose-based fiber includes a step of modifying an unmodified cellulose-based fiber-containing material to obtain the modified cellulose-based fiber-containing material, and a step of defibrating the modified cellulose-based fiber-containing material to obtain the modified cellulose-based fiber.

[0075] The unmodified cellulose fiber-containing material is as described above in the method for producing cellulose fiber (B) (1). The average fiber diameter and defibration method for the modified cellulose fiber-containing material are as described above for the unmodified cellulose fiber-containing material.

[0076] <<Modification Method>> Methods for modifying unmodified cellulosic fiber-containing materials and methods for modifying defibrated unmodified cellulosic fibers can use known methods for modifying hydroxyl groups of cellulosic polymers with substituents. Examples of such methods include the method described in WO 2019 / 163873.

[0077] For example, an acetylation reaction in which hydrogen atoms of hydroxyl groups in a cellulose-based polymer are converted to acetyl groups can be performed using a method comprising the steps of suspending an unmodified cellulose-based fiber-containing material in an anhydrous aprotic polar solvent capable of swelling the unmodified cellulose-based fiber-containing material and reacting the unmodified cellulose-based fiber-containing material with an acetylating agent in the presence of a base. Examples of the acetylating agent include acetic anhydride and acid chloride. Examples of aprotic polar solvents include N-methylpyrrolidone and N,N-dimethylformamide. Examples of bases include pyridine, N,N-dimethylaniline, sodium carbonate, sodium bicarbonate, and potassium carbonate. The acylation reaction is preferably carried out at room temperature (e.g., 25°C) to 100°C while stirring the raw material components. The degree of acetylation of the acetylated cellulose-based fiber can be adjusted by adjusting the amount of acetylating agent, reaction temperature, reaction time, etc.

[0078] In addition, modification methods other than acetylation reactions include, for example, the methods described in WO 2019 / 163873.

[0079] [Number of Cellulosic Fiber (B) Aggregates] In a type A1 test piece prepared from the thermoplastic resin composition in accordance with ISO 294-1, the number of cellulosic fiber (B) aggregates exceeding 100 μm × 100 μm (also simply referred to as "cellulosic fiber (B) aggregates") is 30 mm２ It is characterized in that there are two or less per unit.

[0080] If the number of aggregates of the cellulose fiber (B) exceeds two, the tensile breaking strain is poor. The number of aggregates of the cellulose fiber (B) tends to increase as the average fiber length of the cellulose fiber (B) increases. The number of aggregates of the cellulose fiber (B) can be evaluated by the following method.

[0081] Specifically, a thin section having a thickness of 16 μm is cut from the Type A1 test piece on the TD plane using a microtome, and observed using an optical microscope or a digital microscope. From the obtained image, the maximum length (I) from one point to another on the periphery of the aggregate of cellulose fiber (B) is measured. Next, the maximum length (II) of the lengths perpendicular to (I) is measured. When the lengths (I) and (II) exceed 100 μm, the number of aggregates is counted as one.

[0082] (Other Components (C)) The thermoplastic resin composition may contain other components as long as the effects of the present invention are not impaired. Examples of such components include defibrating aids, water, compatibilizers, surfactants, polysaccharides (starch, alginic acid, etc.), natural proteins (gelatin, glue, casein, etc.), inorganic compounds (tannin, zeolite, ceramics, metals, etc.), antioxidants, heat stabilizers, flame retardants, crystallization accelerators, colorants, plasticizers, fragrances, pigments, flow adjusters, leveling agents, conductive agents, antistatic agents, UV absorbers, UV dispersants, and deodorizers. It is preferable that the thermoplastic resin composition does not contain a polyhydric alcohol.

[0083] <Defibrillating Aid> Examples of the defibrating aid include amide compounds. Specific examples of amide compounds include ε-caprolactam, N-methyl-ε-caprolactam, N-acetyl-ε-caprolactam, laurolactam, δ-valerolactam, N-methyl-δ-valerolactam, undecanelactam, N,N-dimethylacetamide, N,N-dimethylformamide, 2-pyrrolidone, and N-methyl-2-pyrrolidone. ε-caprolactam and laurolactam are more preferred as the defibrating aid, and ε-caprolactam is particularly preferred.

[0084] Components other than the defibrating aid can be appropriately selected from components that are commonly used in thermoplastic resin compositions containing thermoplastic resins and cellulosic fibers.

[0085] (Content of Each Component) The preferred contents of each component in the thermoplastic resin composition are as follows. The content of the thermoplastic resin (A) is preferably 50% by mass to 99% by mass, and particularly preferably 60% by mass to 95% by mass, relative to 100% by mass of the thermoplastic resin composition. From the viewpoint of mechanical properties including tensile strain at break, the content of the cellulose-based fiber (B) is preferably 1% by mass to 35% by mass, and particularly preferably 5% by mass to 30% by mass, relative to 100% by mass of the thermoplastic resin composition. The total content of the other component (C) is preferably 0% by mass to 25% by mass, and particularly preferably 0% by mass to 20% by mass, relative to 100% by mass of the thermoplastic resin composition. Furthermore, when the other component (C) is water, the water content in the thermoplastic resin composition is preferably less than 1% by mass, more preferably less than 0.5% by mass, and particularly preferably less than 0.1% by mass, relative to 100% by mass of the thermoplastic resin composition. A thermoplastic resin composition having such a water content can efficiently produce a good molded article. The water content of the thermoplastic resin composition can be adjusted by subjecting the thermoplastic resin composition produced by the method for producing a thermoplastic resin composition described below to a drying treatment.

[0086] [Method for producing thermoplastic resin composition] The method for producing the thermoplastic resin composition is not particularly limited as long as it is a method that can produce a desired thermoplastic resin composition. Examples of the method for producing the thermoplastic resin composition include the following first to third methods for producing a thermoplastic resin composition.

[0087] (Production Method 1) A first production method (production method 1) of a thermoplastic resin composition includes the following step (1A): (1A) melt-kneading a thermoplastic resin (A), a cellulosic fiber (B), and optionally other components (C) to obtain a thermoplastic resin composition.

[0088] Production method 1 is a method in which the components contained in the thermoplastic resin composition are melt-kneaded together. The order of addition of each component is arbitrary.

[0089] (Production Method 2) A second production method (production method 2) of a thermoplastic resin composition includes the following step (2A): (2A) melt-kneading a thermoplastic resin (A), a cellulose-based fiber-containing material, and optionally other components (C) to obtain a thermoplastic resin composition.

[0090] In the production method 2, the cellulose-based fiber-containing material and the thermoplastic resin (A) are melt-kneaded together. In the production method 2, the defibration of the cellulose-based fiber-containing material proceeds due to the shear stress during the kneading.

[0091] (Production Method 3) A third production method (Production Method 3) of a thermoplastic resin composition includes the following steps (3A) and (3B): (3A) a step of obtaining a masterbatch, which includes the following step (3A-1) or step (3A-2): (3A-1) a step of melt-kneading a thermoplastic resin (A), a cellulose-based fiber (B), and optionally other components (C) to obtain a masterbatch, or (3A-2) a step of melt-kneading a thermoplastic resin (A), a cellulose-based fiber-containing material, and optionally other components (C) to obtain a masterbatch, and (3B) a step of melt-kneading the masterbatch with a further thermoplastic resin (A) to obtain a thermoplastic resin composition.

[0092] Production method 3 is a so-called masterbatch method. Step (3A) is a masterbatch kneading step, and step (3B) is a dilution kneading step. Here, step (3A-1) corresponds to step (1A). Step (3A-2) corresponds to step (2A). That is, in production methods 1 and 2, the thermoplastic resin composition may be obtained as a masterbatch. The masterbatch obtained in this manner can be melt-kneaded with additional thermoplastic resin (A) so as to be diluted, thereby obtaining a desired thermoplastic resin composition.

[0093] (Melt-Kneading) In the melt-kneading in Production Method 1 and Production Method 2, and in the melt-kneading in the step of obtaining a masterbatch in Production Method 3, the cellulose-based fiber (B) or the cellulose-based fiber-containing material may contain water. In this case, water corresponds to the optionally used other component (C). The moisture content of the cellulose-based fiber (B) or the cellulose-based fiber-containing material is preferably less than 40% by mass, more preferably less than 20% by mass, and particularly preferably less than 10% by mass, based on the total amount of cellulose-based fiber (B) contained in the composition. Furthermore, the moisture content of the cellulose-based fiber (B) or the cellulose-based fiber-containing material is preferably 1% by mass or more, more preferably 2% by mass or more, and particularly preferably 3% by mass or more, based on the total amount of cellulose-based fiber (B) contained in the composition. By melt-kneading using cellulose-based fibers (B) or a cellulose-based fiber-containing material having such a moisture content, defibration of the cellulose-based fiber-containing material is further promoted or aggregation of the cellulose-based fibers (B) is suppressed, thereby easily obtaining a thermoplastic resin composition in which the cellulose-based fibers (B) are well dispersed in the thermoplastic resin (A). This allows for efficient production of a molded article of the thermoplastic resin composition with few aggregates of the cellulose-based fibers (B). Furthermore, by melt-kneading using cellulose-based fibers (B) or a cellulose-based fiber-containing material having such a moisture content, a thermoplastic resin composition having the above-mentioned water content can be efficiently obtained. At least a portion of the water contained in the cellulose-based fibers (B) or the cellulose-based fiber-containing material may evaporate during melt-kneading, or may be present in the thermoplastic resin composition as another component (C).

[0094] The moisture content of the cellulose-based fiber (B) or the cellulose-based fiber-containing material can be adjusted to the above-mentioned range by appropriately adjusting the specific surface area, pore size, impurities, functional group, etc. of the cellulose-based fiber (B) or the cellulose-based fiber-containing material. The moisture content of the cellulose-based fiber (B) or the cellulose-based fiber-containing material can also be adjusted by drying the cellulose-based fiber (B) or the cellulose-based fiber-containing material.

[0095] The melt-kneading in Production Method 1 and Production Method 2, and the melt-kneading in the step of obtaining the masterbatch in Production Method 3 may be carried out in the presence or absence of the above-mentioned defibrating aid and / or water.

[0096] <Melt-Kneading Temperature> The melt-kneading temperature can be appropriately set depending on the thermoplastic resin (A), but is preferably 220 to 250° C. When the temperature during melt-kneading is within the above range, the thermoplastic resin (A) and the cellulosic fibers (B) can be uniformly mixed.

[0097] (Dilution and kneading) Step (3B) is a dilution and kneading step. The conditions for dilution and kneading are the same as those for melt kneading. Dilution and kneading may be performed in the presence or absence of a defibration aid and / or water.

[0098] <Amount Used> The amounts of component (A) and component (B) used in melt-kneading may be amounts that correspond to the content of each component in the thermoplastic resin composition. Furthermore, in production method 3, when a masterbatch is obtained, the amount of component (B) used is preferably 10 to 40 parts by mass per 100 parts by mass of the total of components (A) and (B). The amount of component (C) used in melt-kneading is not particularly limited as long as the function and properties of component (B) are maintained, but is preferably 0 to 25 parts by mass per 100 parts by mass of the total of components (A) and (B). When the other component (C) is water, the amount of water used is preferably an amount that corresponds to the moisture content of component (B) described above.

[0099] [Uses] The thermoplastic resin composition can be used for a molded article. Furthermore, since the thermoplastic resin composition has excellent impact resistance and flexural strength, a molded article containing the thermoplastic resin composition (a molded article using the thermoplastic resin composition) can be a molded article requiring impact resistance, a molded article requiring flexural strength, or a molded article requiring impact resistance and flexural strength. Examples of the shape of the molded article include a film, sheet, plate, pellet, rod, powder, hollow, etc.

[0100] Molded articles containing a thermoplastic resin composition can be produced by molding the thermoplastic resin composition using various known molding methods, such as mold molding, injection molding, extrusion molding, blow molding, and foam molding. The method for producing a molded article using a thermoplastic resin composition is preferably a manufacturing method including a step of molding the thermoplastic resin composition by injection molding to obtain a molded article. The injection molding machine is not particularly limited, and examples include a screw in-line injection molding machine and a plunger injection molding machine. The thermoplastic resin composition is heated and melted in the cylinder of the injection molding machine, measured for each shot, injected into a mold in a molten state, cooled and solidified into a predetermined shape, and then removed from the mold as a molded article. The resin temperature during injection molding is preferably equal to or higher than the melting point of the thermoplastic resin composition, particularly the thermoplastic resin (A), and particularly preferably less than "melting point + 100°C."

[0101] Molded articles containing the thermoplastic resin composition containing cellulose-based fibers according to the present invention are lighter and have superior strength properties compared to molded articles containing thermoplastic resin compositions containing only inorganic fibers such as glass fibers or carbon fibers. Molded articles containing the thermoplastic resin composition containing cellulose-based fibers can be used as components for transportation equipment, electrical appliances, or building materials. Specifically, they can be used for interior, exterior, and structural materials (e.g., gears, pulleys, cams, bearings, cable housings, etc.) for transportation equipment such as automobiles, trains, ships, and airplanes; housings, structural materials, and internal parts for electrical appliances such as personal computers, televisions, and telephones; and building materials. Furthermore, thermoplastic resin compositions containing cellulose-based fibers can contribute to achieving Goals 9 and 13 of the Sustainable Development Goals (SDGs) by reducing the weight of molded articles and thereby contributing to reducing resource consumption.

[0102] The present invention will be specifically explained below with reference to examples and comparative examples, but the present invention is not limited to these.

[0103] [Preparation of Test Pieces] Using the pellet mixtures of the thermoplastic resin compositions of the Examples and Comparative Examples, Type A1 test pieces and Type B test pieces were prepared in accordance with ISO 294-1 using an injection molding machine SE100D-C160S manufactured by Sumitomo Heavy Industries, Ltd.

[0104] [Evaluation] (1) Density The density of the thermoplastic resin composition was determined according to ISO 1183. (2) Tensile Strength and Tensile Breaking Strain A tensile test was performed in a 23°C atmosphere using a Type A1 test piece of the thermoplastic resin composition according to ISO 527-1, 2. A tensile break strain of 3.0% or more was deemed to be excellent in "tensile break strain." (3) Flexural Strength and Flexural Modulus A flexural test was performed in a 23°C atmosphere using a Type B test piece of the thermoplastic resin composition according to ISO 178. (4) Charpy Impact Strength A Charpy impact test was performed in a 23°C atmosphere using a Type B test piece of the thermoplastic resin composition, V-notched according to ISO 179 / 1eA. (5) Bulk Density The bulk density of the cellulose fiber (B) was measured according to JIS K 5101. (6) Moisture Content (6-1) The moisture content of the cellulose fiber (B) was determined by holding a sample at 90°C for 10 hours or more in a vacuum dryer, and the mass at the point when no further change in mass was observed was taken as the post-drying mass, and the value was calculated using the following formula: Moisture content of cellulose fiber (B) (mass%) = [(mass before drying - mass after drying) ÷ mass before drying] × 100 (6-2) The moisture content of the thermoplastic resin composition was determined by heating and vaporizing the water in 1 g of the thermoplastic resin composition at 215°C under a nitrogen stream, introducing the vapor into the titration cell of a coulometric titrator, and performing automatic measurement (Karl Fischer coulometric titration). (7) Dispersibility of pulp in a Type A1 test piece prepared in accordance with ISO 294-1 (presence and number of aggregates of cellulose fiber (B)): The TD surface of the Type A1 test piece was cut using a microtome to obtain a thin section with a thickness of 16 μm. The presence or absence of aggregates of cellulose-based fibers (B) was confirmed in a 3.8 mm × 9.0 mm region of the thin section using an optical microscope. ２(8) Relative viscosity: In accordance with JIS K-6920, 1 g of polyamide was dissolved in 100 ml of 96 wt % concentrated sulfuric acid, and the relative viscosity was measured at 25°C.

[0105] <Components Used> The following components were used: 1. Thermoplastic resin (A): Polyamide 6 (manufactured by UBE, relative viscosity 2.47) Polyamide 12 (manufactured by UBE, relative viscosity 1.85) 2. Cellulose-based fibers (B): Cotton: Cotton powder #20 (unmodified, manufactured by Sanyo Chemical Industries, Ltd., bulk density 0.06 g / mL, moisture content 5% by mass, average fiber diameter (D) 23 μm, average fiber length (L) 330 μm) Cotton: Cotton powder #80 (unmodified, manufactured by Sanyo Chemical Industries, Ltd., bulk density 0.15 g / mL, moisture content 4% by mass, average fiber diameter (D) 23 μm, average fiber length (L) 220 μm) Hardwood pulp: pure pulp 5 mm (unmodified, manufactured by Sanyo Chemical Industries, Ltd., bulk density 0.02 g / mL, moisture content 5% by mass, average fiber diameter (D) 21 μm, average fiber length (L) 300 μm) Hardwood pulp: pure pulp #4000 (unmodified, manufactured by Sanyo Chemical Industries, bulk density 0.20 g / mL, moisture content 5% by mass, average fiber diameter (D) 10 μm, average fiber length (L) 40 μm) Recycled pulp: BKP-A (unmodified, manufactured by Yamato Shiryo Co., Ltd., bulk density 0.09 g / mL, moisture content 40% by mass, average fiber diameter (D) 18 μm, average fiber length (L) 1,270 μm) Softwood pulp: crushed pulp (unmodified, manufactured by Chuetsu Pulp Co., Ltd., bulk density 0.11 g / mL, moisture content 50% by mass, average fiber diameter (D) 30 μm, average fiber length (L) 1,900 μm) Unbleached pulp: Cellofiber (unmodified, manufactured by Hyogo Pulp Industries Co., Ltd., bulk density 0.43 g / mL, moisture content 74% by mass, average fiber diameter (D) 13 μm, average fiber length (L) 1,310 μm)

[0106] Example 1 Polyamide 6 was used as the thermoplastic resin (A), and cotton powder #20 was used as the cellulosic fiber (B). 90% by mass of the thermoplastic resin (A) and 10% by mass (solids content) of the cellulosic fiber (B) were fed into a twin-screw melt kneader (manufactured by Coperion Co., Ltd., model ZSK32Mc) and melt-kneaded at a cylinder temperature of 230°C. The melt-kneaded product was extruded into a strand shape, cooled and solidified by water cooling, and cut with a pelletizer to obtain a thermoplastic resin composition.

[0107] <Examples 2 to 4> Thermoplastic resin compositions were obtained in the same manner as in Example 1, except that the ratios of the thermoplastic resin (A) and the cellulosic fiber (B) were changed to the values ​​shown in Table 1.

[0108] Examples 5 to 7, Comparative Examples 1 and 3 Thermoplastic resin compositions were obtained in the same manner as in Example 2, except that the cellulosic fibers (B) were changed to the types shown in Table 1.

[0109] Comparative Example 2 A thermoplastic resin composition was obtained in the same manner as in Example 4, except that the type of cellulosic fiber (B) was changed to that shown in Table 1.

[0110] Example 8 Polyamide 12 was used as the thermoplastic resin (A), and cotton powder #20 was used as the cellulosic fiber (B). 75% by mass of the thermoplastic resin (A) and 25% by mass (solids content) of the cellulosic fiber (B) were fed into a twin-screw melt kneader (manufactured by Coperion Co., Ltd., model ZSK32Mc) and melt-kneaded at a cylinder temperature of 230°C. The melt-kneaded product was extruded into a strand shape, cooled and solidified by water cooling, and cut with a pelletizer to obtain a thermoplastic resin composition.

[0111] Example 9: Polyamide 6 was used as the thermoplastic resin (A), and pure pulp #4000 was mechanically pulverized as the cellulose-based fiber (B) to obtain a pure pulp #4000 pulverized product (unmodified, bulk density 0.20 g / mL, moisture content 5% by mass, average fiber diameter (D) 1.5 μm, average fiber length (L) 4.5 μm). 90% by mass of thermoplastic resin (A) and 10% by mass of cellulose-based fiber (B) (solid content) were fed to a twin-screw melt kneader (manufactured by Coperion Co., Ltd., model ZSK32Mc) and melt-kneaded at a cylinder temperature of 230 ° C. The molten mixture was extruded into a strand, cooled and solidified by water cooling, and cut with a pelletizer to obtain a thermoplastic resin composition.

[0112] <Examples 10 to 11> Thermoplastic resin compositions were obtained in the same manner as in Example 8, except that the ratios of the thermoplastic resin (A) and the cellulose-based fiber (B) were changed to the values ​​shown in Table 1.

[0113] The results are shown in Table 1.

[0114]

[0115] As shown in Table 1, the thermoplastic resin compositions of the Examples had excellent tensile break strains. The thermoplastic resin compositions of Examples 1 to 7 and 9 contained polyamide 6 as the thermoplastic resin (A). A comparison of Examples 1 to 4 showed that the tensile break strains were better when the content of cellulosic fiber (B) was lower. A comparison of Examples 2 and 5-6 with Example 7 showed that the bending strength was better when the (L / D) ratio of the cellulosic fiber (B) was 8 or more. A comparison of Example 1 with Example 9 showed that the tensile break strains were better when the (L / D) ratio of the cellulosic fiber (B) was 5 or more. Furthermore, a comparison of Examples 2 and 5-7 with Comparative Examples 1 and 3 showed that the impact strengths of the Examples were greater than or similar to those of the Comparative Examples. Furthermore, a comparison of the above-mentioned Examples showed that the tensile break strains of the Examples were better than those of the Comparative Examples. The same can be said for Example 4 and Comparative Example 2.

[0116] The thermoplastic resin compositions of Examples 4 and 8 have the same content of thermoplastic resin (A). A comparison between Examples 4 and 8 revealed that the tensile break strain was excellent regardless of whether the thermoplastic resin (A) was polyamide 6 or polyamide 12. A comparison between Examples 4 and 8 revealed that the tensile break strain was superior when the thermoplastic resin (A) was polyamide 12. A comparison between Examples 4 and 8 revealed that the flexural strength was superior when the thermoplastic resin (A) was polyamide 6. The same can be said for Examples 2 and 11.

[0117] The average fiber length of the cellulose-based fibers of Comparative Examples 1 to 3 exceeds 1,000 μm. In addition, in the type A1 test pieces prepared according to ISO 294-1 using the thermoplastic resin compositions of Comparative Examples 1 to 3, the aggregates of the cellulose-based fibers were 30 mm or less. ２ Therefore, the compositions of Comparative Examples 1 to 3 were inferior in tensile breaking strain.

Claims

1. A thermoplastic resin composition comprising a thermoplastic resin (A) and a cellulose fiber (B) having an average fiber length of 2 to 1,000 μm, wherein in a type A1 test piece prepared from the thermoplastic resin composition in accordance with ISO 294-1, aggregates of the cellulose fiber (B) exceeding 100 μm × 100 μm are 2 or less per 30 mm ２ The thermoplastic resin composition.

2. The thermoplastic resin composition according to claim 1, wherein the average fiber diameter of the cellulose-based fiber (B) is 1 μm to 45 μm.

3. The thermoplastic resin composition according to claim 1, wherein the ratio (L / D) of the average fiber length to the average fiber diameter of the cellulose-based fiber (B) is 2 to 30.

4. The thermoplastic resin composition according to claim 1, wherein the cellulose-based fiber (B) is an unmodified cellulose-based fiber.

5. The thermoplastic resin composition according to claim 1, wherein the content of the cellulose-based fiber (B) is 1% by mass to 35% by mass based on 100% by mass of the thermoplastic resin composition.

6. The thermoplastic resin composition according to claim 1, wherein the thermoplastic resin (A) is at least one selected from the group consisting of a polyamide resin, a polyolefin resin, a halogenated polyolefin resin, a polystyrene resin, a polycarboxylic acid vinyl resin, a polyurethane resin, an acrylonitrile-diene-styrene resin, an acrylic resin, a polyether resin, a polycarbonate resin, a polyester resin, a polyamide-based elastomer, and a composite resin containing these as constituent components.

7. A molded article comprising the thermoplastic resin composition according to any one of claims 1 to 6.

8. The molded article according to claim 7, which is a member for a transportation machine, an electric appliance, or a building material.

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