High toughness polyamide-cellulose resin composition

Abstract

To provide a resin composition in which low density, low thermal expansion property, low anisotropy, high toughness and high physical stability are achieved at the same time, and in particular, high toughness and low thermal expansion property that are conflicting characteristics are highly compatible.SOLUTION: A resin composition includes one or more kinds of elastomers selected from the group consisting of polyamide, aromatic vinyl compound-conjugated diene compound block copolymer and its derivatives, and cellulose. The polyamide and the elastomer are phase separated. Exceeding 50 mass% of the cellulose is present in a polyamide phase.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a cellulose-containing resin composition that combines high toughness and low thermal expansion at a high level. [Background technology]

[0002] Thermoplastic resins are lightweight and have excellent processability, making them widely used in a variety of applications, including automotive components, electrical and electronic components, office equipment housings, and precision components. In particular, the automotive industry has long been replacing metal components with resin components in order to improve fuel efficiency. In recent years, China, Europe, and other regions have begun to rapidly promote the transition to electric vehicles, leading to the development of electric vehicles. Therefore, reducing vehicle weight to extend the driving range of electric vehicles has become an urgent issue. Replacing metal components with resin components is an effective way to reduce the weight of automobiles, and automakers are stepping up their efforts, particularly in the use of resin for exterior components with large volumes, as this contributes significantly to weight reduction.

[0003] Polypropylene-based materials are widely used for plastic exterior parts, primarily bumpers. Furthermore, for vertical parts such as fenders, the use of polyamide / polyphenylene ether alloy materials, such as those described in Patent Document 1, is being considered for their rigidity, heat resistance, and other properties. Furthermore, in order to further improve dimensional accuracy, Patent Documents 2 and 3, for example, consider blending inorganic fillers. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2002 / 094936 [Patent Document 2] International Publication No. 2006 / 077818 [Patent Document 3] Japanese Patent Application Laid-Open No. 2006-199748 Summary of the Invention [Problem to be solved by the invention]

[0005] However, polypropylene-based materials do not have sufficient rigidity and are therefore unsuitable for plate-shaped vertical components (door panels, fenders, etc.) Furthermore, although polyamide / polyphenylene ether-based alloy materials have the rigidity required for fenders and the like, they have the problem of having a high thermal expansion coefficient (generally around 90 ppm / K).

[0006] Automobiles are expected to be driven in a variety of environments. For example, the difference in component surface temperature between freezing cold and the desert can be as much as 100°C. The thermal expansion coefficient of this alloy material translates into a dimensional variation of approximately 6 mm for a 70 cm long component. In this case, to prevent contact with adjacent components due to thermal expansion, it becomes necessary to provide a gap of several millimeters in advance. This poses a major challenge for passenger cars, where design is a priority.

[0007] One possible technique for suppressing the coefficient of thermal expansion is to incorporate inorganic fillers. However, the materials obtained using this technique have new issues, such as the weight reduction effect achieved by using resin components being lost due to the addition of high-density inorganic fillers, reduced impact strength, warping and anisotropy in the product, and poor stability of physical properties, which has prevented the material from being widely adopted.

[0008] On the other hand, automotive exterior parts (for example, bumpers, fenders, hoods, roofs, etc.) are large and therefore require further improvements in thermal expansion and toughness, and the reality is that the replacement of metal parts with resin parts has not progressed. In other words, at present, no resin composition has been obtained that can achieve the contradictory properties of high toughness and low thermal expansion at a satisfactory level while ensuring low specific gravity and low anisotropy of physical properties.

[0009] The present invention aims to solve the above problems and provide a resin composition that achieves a high degree of compatibility between the contradictory properties of high toughness and low thermal expansion while ensuring low specific gravity and low anisotropy of physical properties. [Means for solving the problem]

[0010] As a result of investigations aimed at solving the above-mentioned problems, the present inventors discovered that the above-mentioned problems can be solved by a resin composition containing a polyamide as a thermoplastic resin, a specific elastomer, and cellulose, in which the cellulose is selectively present mainly in the polyamide phase, and thus completed the present invention.

[0011] That is, the present invention includes the following aspects. [1] Polyamide, one or more elastomers selected from the group consisting of aromatic vinyl compound-conjugated diene compound block copolymers and derivatives thereof; and cellulose, A resin composition comprising: the polyamide and the elastomer are phase-separated, A resin composition, wherein more than 50% by mass of the cellulose is present in the polyamide phase. [2] The resin composition according to the above aspect 1, wherein the polyamide forms a continuous phase and the elastomer forms a dispersed phase. [3] The resin composition according to aspect 1 or 2, wherein the polyamide is at least one selected from the group consisting of polyamide 6, polyamide 10, polyamide 11, polyamide 12, polyamide 66, polyamide 610, polyamide 612, polyamide 6 / 6I, polyamide 66 / 6I, polyamide 6I, and mixtures thereof. [4] Viscosity number (V) of polyamide measured in 96% sulfuric acid according to ISO 307 N 4. The resin composition according to any one of the above aspects 1 to 3, wherein ) is 200 or less. [5] The resin composition according to any one of the above aspects 1 to 4, wherein the ratio [NH2] / [COOH] of the terminal amino group concentration [NH2] to the terminal carboxyl group concentration [COOH] in the polyamide is greater than 1. [6] The resin composition according to any one of the above aspects 1 to 5, wherein the amount of the elastomer is 1 to 50 parts by mass per 100 parts by mass of the polyamide. [7] The resin composition according to any one of the above aspects 1 to 6, wherein the amount of the elastomer is 5 to 45 parts by mass per 100 parts by mass of the polyamide. [8] The resin composition according to any one of the above aspects 1 to 7, wherein the derivative includes an acid-modified product of an aromatic vinyl compound-conjugated diene compound block copolymer. [9] The resin composition according to aspect 8, wherein the elastomer is a mixture of a polymer having an acidic functional group and a polymer not having an acidic functional group.

[10] A value X obtained by multiplying the amino group terminal concentration [NH2] (mmol / g) of the polyamide by the content (mass%) of the polyamide in the resin composition; and a value Y obtained by multiplying the acidic functional group concentration (mmol / g) of the polymer having an acidic functional group by the content (mass%) of the polymer having an acidic functional group in the resin composition, which is calculated by the following formula: 10≦X / Y≦50 The resin composition according to aspect 9, wherein the following relationship is satisfied:

[11] The resin composition according to any one of the above aspects 1 to 10, wherein the elastomer is a mixture of an aromatic vinyl compound-conjugated diene compound block copolymer and a hydrogenated product of the aromatic vinyl compound-conjugated diene compound block copolymer.

[12] The elastomer is present as dispersed particles in a polyamide continuous phase; 12. The resin composition according to any one of the above embodiments 1 to 11, wherein the dispersed particles have a number average particle size of 3 μm or less.

[13] The elastomer is present as dispersed particles in a polyamide continuous phase; 13. The resin composition according to any one of the above-mentioned embodiments 1 to 12, wherein the dispersed particles have a volume ratio of particles having a particle size of 1 μm or more of 30% by volume or less.

[14] The resin composition according to any one of the above aspects 1 to 13, wherein the amount of cellulose is 0.1 to 30% by mass, based on 100% by mass of the resin composition.

[15] The resin composition according to any one of aspects 1 to 14, wherein the cellulose is a cellulose nanofiber having a diameter of 50 to 1000 nm and a length (L) / diameter (D) ratio of 30 or more, a cellulose nanocrystal having a diameter of 100 nm or less and a length (L) / diameter (D) ratio of less than 30, or a cellulose microfiber having a diameter of more than 1 μm to 50 μm, or a mixture of two or more of these.

[16] The resin composition according to aspect 15, wherein the amount of the cellulose microfibers is 0.1 to 20% by mass, based on 100% by mass of the resin composition.

[17] The resin composition according to any one of the above aspects 1 to 16, wherein the cellulose is hydrophobized cellulose.

[18] The resin composition according to any one of the above aspects 1 to 17, further comprising a conductive carbonaceous filler.

[19] The resin composition according to any one of Aspects 1 to 18, further comprising an antioxidant.

[20] The resin composition according to any one of the above aspects 1 to 19, further comprising a colorant.

[21] The resin composition according to any one of the above aspects 1 to 20, having a thermal expansion coefficient of 60 ppm / K or less at 20°C to 100°C.

[22] A molded article made of the resin composition according to any one of the above aspects 1 to 21. [Effects of the Invention]

[0012] According to one aspect of the present invention, a resin composition can be provided that simultaneously achieves low specific gravity, low thermal expansion, low anisotropy, high toughness, and high physical property stability, and in particular, achieves a high degree of compatibility between the contradictory properties of high toughness and low thermal expansion. [Brief explanation of the drawings]

[0013] [Figure 1] Figure 1 is a microscopic image showing an example of cellulose nanocrystals. [Figure 2] Figure 2 is a microscopic image showing an example of cellulose nanofibers. [Figure 3] FIG. 3 is a microscopic image showing an example of cellulose microfibers. DETAILED DESCRIPTION OF THE INVENTION

[0014] Exemplary embodiments of the present invention will be specifically described below, but the present invention is not limited to these embodiments.

[0015] In one aspect of the present invention, the resin composition contains one or more elastomers selected from the group consisting of polyamides, aromatic vinyl compound-conjugated diene compound block copolymers and derivatives thereof (hereinafter also referred to as the elastomer of this embodiment), and cellulose. The polyamide and the elastomer are phase-separated, with more than 50% by mass of the cellulose being present in the polyamide phase. In a typical embodiment, the resin composition has a two-phase structure consisting of a polyamide phase and an elastomer phase. Although it is not excluded that the resin composition of this embodiment may have three or more phases, the following describes a resin composition having a two-phase structure consisting of a polyamide phase and an elastomer phase, which is a typical embodiment of this embodiment.

[0016] The phase morphology of the resin composition of this embodiment may be a morphology in which the polyamide forms a continuous phase and the elastomer forms a dispersed phase, a morphology in which the polyamide forms a dispersed phase and the elastomer forms a continuous phase, or a morphology in which both the polyamide and the elastomer form continuous phases (i.e., a co-continuous phase structure). However, a morphology in which the polyamide forms a continuous phase and the elastomer forms a dispersed phase is preferred in that the composition exhibits good heat resistance and achieves high rigidity and low linear expansion.

[0017] Generally, cellulose is considered to have a high affinity with polyamides due to its hydrophilicity. Furthermore, it is believed that finely divided cellulose may be entangled in highly viscous elastomer components. Furthermore, it is known that the location of cellulose in a resin composition that has been subjected to a hydrophobic treatment, as described below, changes depending on the kneading conditions due to a decrease in hydrophilicity.

[0018] The lower limit of the proportion of cellulose present in the polyamide phase in the resin composition of this embodiment is greater than 50% by mass, preferably 60% by mass, more preferably 70% by mass, even more preferably 75% by mass, even more preferably 80% by mass, and most preferably 100% by mass (i.e., substantially all of the cellulose is present in the polyamide phase). By setting this proportion within the above range, it is possible to simultaneously achieve various contradictory properties, such as low thermal expansion, low anisotropy, and high toughness. The upper limit of this proportion may be, for example, 99% by mass or 98% by mass, from the viewpoint of ease of production of the resin composition.

[0019] As an example of a method for confirming that more than 50% by mass of cellulose is present in the polyamide phase, for example, when the cellulose content differs significantly between the polyamide phase and the elastomer phase, quantification is not necessary; instead, the resin composition is photographed with a transmission electron microscope to confirm the amount of cellulose present in the polyamide phase and the amount of cellulose present in the elastomer phase. If quantification is required, the resin composition is sliced ​​to a thickness of approximately 0.1 to 2 μm to obtain a film sample. The sample is immersed in a solvent (e.g., chloroform, toluene, etc.) that dissolves elastomer components but not polyamide to elute the elastomer phase. The eluate is concentrated and then subjected to ultracentrifugation to separate the cellulose present in the elastomer phase. The cellulose is then washed with the solvent at least three times, dried, and the amount of cellulose present in the elastomer phase is measured.

[0020] Next, each component that can be used in this embodiment will be described in detail.

[0021] <Polyamide> Examples of polyamides used in the present invention include polycondensates of dibasic acids and diamines, ring-opening polymers of cyclic lactams, polycondensates of aminocarboxylic acids, and copolymers and blends thereof. More specifically, aliphatic polyamides such as polyamide 6, polyamide 10, polyamide 11, polyamide 12, polyamide 46, polyamide 66, polyamide 610, and polyamide 612, aromatic polyamide resins such as polymetaxylene adipamide (polyamide MXD6), polyhexamethylene terephthalamide (polyamide 6T), and polyhexamethylene isophthalamide (polyamide 6I), and copolymers and blends such as polyamide 6 / 6I, polyamide 66 / 6I, polyamide 6 / 6T, polyamide 66 / 6T, polyamide 6 / 66 / 6T, polyamide 6 / 66 / 6I, polyamide 9T, and polyamide 10T can be used. Among these, polyamide 6, polyamide 10, polyamide 11, polyamide 12, polyamide 66, polyamide 610, polyamide 612, polyamide 6 / 6I, polyamide 66 / 6I, polyamide 6I, and blends thereof are particularly preferred, and polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 6I, and blends thereof are most preferred.

[0022] Although there is no particular limitation on the terminal carboxyl group concentration of the polyamide, the lower limit is preferably 5 μmol / g, more preferably 10 μmol / g, more preferably 20 μmol / g, more preferably 25 μmol / g, and more preferably 30 μmol / g. The upper limit of the terminal carboxyl group concentration is preferably 150 μmol / g, more preferably 100 μmol / g, and even more preferably 80 μmol / g.

[0023] Although there is no particular limitation on the terminal amino group concentration of the polyamide, the lower limit is preferably 20 μmol / g, more preferably 30 μmol / g, and the upper limit is preferably 150 μmol / g, more preferably 100 μmol / g, and even more preferably 80 μmol / g.

[0024] In the polyamide, the amino terminal group ratio ([NH2] / ([NH2]+[COOH])) is preferably 0.20 to 0.95. The lower limit of the amino terminal group ratio is more preferably 0.3, and even more preferably 0.35. The upper limit of the amino terminal group ratio is more preferably 0.90, even more preferably 0.85, and most preferably 0.80. The amino terminal group ratio is desirably 0.20 or more from the viewpoint of dispersibility of cellulose in the resin composition, and is desirably 0.95 or less from the viewpoint of the color tone of the resulting resin composition.

[0025] In the polyamide, the ratio [NH2] / [COOH] of the amino terminal concentration [NH2] to the carboxy terminal concentration [COOH] is preferably greater than 1, more preferably 1.5 or more, even more preferably 2 or more, and most preferably 2.5 or more, from the viewpoint of dispersibility of cellulose in the resin composition. From the viewpoint of the color tone of the resin composition, the ratio is preferably 10 or less, more preferably 7.5 or less, even more preferably 5.5 or less, and most preferably 4.5 or less.

[0026] The terminal group concentration of the polyamide can be adjusted by any known method, for example, by adding a terminal adjuster that reacts with terminal groups, such as a diamine compound, a monoamine compound, a dicarboxylic acid compound, a monocarboxylic acid compound, an acid anhydride, a monoisocyanate, a monoacid halide, a monoester, or a monoalcohol, to the polymerization solution so that the terminal group concentration is a predetermined value during polymerization of the polyamide.

[0027] Examples of terminal modifiers that react with terminal amino groups include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid; and mixtures of any of these. Among these, from the standpoints of reactivity, stability of the blocked terminals, cost, and the like, one or more terminal modifiers selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, and benzoic acid are preferred, with acetic acid being most preferred.

[0028] Examples of terminal modifiers that react with terminal carboxyl groups include aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine, and naphthylamine; and any mixtures thereof. Among these, one or more terminal modifiers selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline are preferred in terms of reactivity, boiling point, stability of the blocked terminals, cost, etc.

[0029] The concentrations of these amino terminal groups and carboxyl terminal groups are 1 From the viewpoint of accuracy and simplicity, it is preferable to determine the concentration of each end group from the integral value of the characteristic signal corresponding to the end group by H-NMR. As a method for determining the concentration of these end groups, the method described in JP-A-7-228775 is specifically recommended. When using this method, deuterated trifluoroacetic acid is useful as a measurement solvent. 1The number of H-NMR scans required is at least 300, even when measured using an instrument with sufficient resolution. Alternatively, the concentration of terminal groups can be measured by a titration method such as that described in JP-A-2003-055549. However, in order to minimize the influence of additives, lubricants, etc., present in the mixture, 1 Quantitation by H-NMR is more preferred.

[0030] The degree of polymerization of polyamide is not particularly limited, but from the viewpoint of ordinary injection molding processability, the viscosity number (V) of polyamide measured in sulfuric acid with a concentration of 96% by mass in accordance with ISO307 is N ) is preferably 200 or less. A more preferred upper limit is 180, even more preferably 150, even more preferably 140, and most preferably 130. By setting the viscosity number within the above range, it is possible to maintain an appropriate fluidity during molding of the molded product and reduce molding distortion, thereby suppressing anisotropy in the actual molded product. The lower limit of the viscosity number is not particularly limited, but from the viewpoint of obtaining good impact resistance, it is preferably 50, more preferably 60, more preferably 65, and most preferably 70.

[0031] The polyamide in this embodiment may be a mixture of different polyamides. When a mixture of multiple polyamides is used, the various characteristic values ​​of the polyamide may be average values ​​of the multiple polyamides.

[0032] The method for polymerizing polyamide is not particularly limited, and may be any of melt polymerization, interfacial polymerization, solution polymerization, bulk polymerization, solid-state polymerization, and a combination thereof. Among these, melt polymerization is more preferably used from the viewpoint of polymerization controllability.

[0033] Furthermore, for the purpose of improving the heat resistance stability of the polyamide resin, known metal stabilizers such as those described in JP-A-1-163262 may be used. Particularly preferred examples of metal stabilizers include CuI, CuCl2, copper acetate, and cerium stearate. Alkali metal halide salts, such as potassium iodide and potassium bromide, can also be suitably used. These may, of course, be added in combination. The preferred total amount of the metal stabilizer and / or alkali metal halide salt is 0.001 to 5 parts by mass per 100 parts by mass of polyamide. From the viewpoint of heat aging resistance, the amount is preferably equal to or greater than the lower limit mentioned above, and from the viewpoint of maintaining high toughness, the amount is preferably equal to or less than the upper limit mentioned above.

[0034] Furthermore, in addition to the above, known additives that can be added to polyamides may be added in an amount of, for example, less than 10 parts by mass per 100 parts by mass of polyamide.

[0035] <Elastomer> The resin composition of this embodiment contains an aromatic compound-conjugated diene compound block copolymer and / or an elastomer that is a derivative thereof. In this disclosure, the term "elastomer" refers to a substance (specifically, a natural or synthetic polymeric substance) that is elastic at room temperature (23°C).

[0036] In the present disclosure, an aromatic compound-conjugated diene compound block copolymer refers to a block copolymer composed of a polymer block (A) primarily composed of an aromatic vinyl compound and a polymer block (B) primarily composed of a conjugated diene compound. Block copolymers in which the bonding type of each block is either AB, ABA, or ABAB are preferred from the viewpoint of impact strength, with ABA or ABAB being more preferred. Furthermore, a derivative of an aromatic compound-conjugated diene compound block copolymer refers to a polymer that retains the main structure of the block copolymer but has a different structure due to modification, hydrogenation, or the like. In one embodiment, the derivative is a modified product (e.g., an acid-modified product) and / or a hydrogenated product of the aromatic compound-conjugated diene compound block copolymer.

[0037] The aromatic vinyl compound-conjugated diene compound block copolymer may be a mixture of two or more types, such as those having different bonding types, different molecular weights, different types of aromatic vinyl compounds, different types of conjugated diene compounds, different 1,2-vinyl contents or the total amount of 1,2-vinyl and 3,4-vinyl contents, different aromatic vinyl compound component contents, or different hydrogenation rates.

[0038] The mass ratio of the aromatic vinyl compound unit to the conjugated diene compound unit in the block copolymer is desirably 10 / 90 to 70 / 30, more preferably 15 / 85 to 55 / 45, and most preferably 20 / 80 to 45 / 55. Furthermore, these may be blends of two or more compounds with different mass ratios of aromatic vinyl compound to conjugated diene compound. Specific examples of aromatic vinyl compounds include styrene, α-methylstyrene, vinyltoluene, etc., and one or more compounds selected from these may be used, with styrene being particularly preferred.

[0039] Specific examples of the conjugated diene compound include butadiene, isoprene, piperylene, 1,3-pentadiene, etc., and one or more compounds selected from these can be used. Among these, butadiene, isoprene, and combinations thereof are preferred, and butadiene is particularly preferred.

[0040] It has been unexpectedly discovered that the aromatic vinyl compound-conjugated diene compound block copolymer and / or its derivative elastomer can impart high toughness and a low thermal expansion coefficient to the resin composition. Without wishing to be bound by theory, it is believed that the double bonds in the aromatic vinyl compound-conjugated diene compound block copolymer and its derivatives can crosslink molecules, resulting in low molecular mobility. In resin compositions containing a combination of polyamide and elastomer, the elastomer contributes to improved toughness by forming domains, but its tendency to thermally expand more readily than polyamide contributes to increasing the thermal expandability of the resin composition. However, the elastomer of this embodiment is believed to be able to reduce the thermal expandability of the resin composition due to the crosslinking of the elastomer molecules. Thus, a resin composition containing the elastomer of this embodiment can unexpectedly combine the contradictory properties of high toughness and low thermal expansion to a high degree.

[0041] Furthermore, when the elastomer contains an acid-modified compound, the formation of crosslinks between the molecules as described above also contributes to suppressing the reaction between cellulose and acidic functional groups, which has the advantage of preventing an increase in the thermal expansion coefficient of the resin composition due to the adhesion of the elastomer to the cellulose (i.e., a decrease in the thermal expansion coefficient reducing effect due to the difficulty of having the cellulose reside mainly in the polyamide phase).

[0042] The number average molecular weight (Mn) of each of the aromatic vinyl compound-conjugated diene compound block copolymer and its derivative is preferably 10,000 to 500,000, more preferably 40,000 to 250,000, from the viewpoint of achieving both impact strength and fluidity. The number average molecular weight referred to here is a value measured using a gel permeation chromatography device with chloroform as a solvent at a measurement temperature of 40°C, converted into polystyrene standard.

[0043] In one embodiment, a derivative of an aromatic vinyl compound-conjugated diene compound block copolymer includes an acid-modified product of the block copolymer. In one embodiment, an acidic functional group is attached to the molecular skeleton of the block copolymer via a chemical bond. In this disclosure, the acidic functional group refers to a functional group capable of reacting with a basic functional group, and specific examples include a hydroxyl group, a carboxyl group, a carboxylate group, a sulfo group, and an acid anhydride group.

[0044] Examples of the acid-modified product include a modified product obtained by grafting an α,β-unsaturated dicarboxylic acid or a derivative thereof onto an aromatic vinyl compound-conjugated diene compound block copolymer or a hydrogenated product thereof in the presence or absence of a peroxide. In a preferred embodiment, the acid-modified product is an acid anhydride-modified product. Specific examples of the α,β-unsaturated dicarboxylic acid and its derivative include maleic acid, fumaric acid, maleic anhydride, and fumaric anhydride, with maleic anhydride being particularly preferred.

[0045] The elastomer may be a mixture of a polymer having an acidic functional group and a polymer not having an acidic functional group, or may be composed entirely of a polymer having an acidic functional group. When the total of the polymer having an acidic functional group (acid-modified product) and the polymer not having an acidic functional group (non-acid-modified product) is taken as 100% by mass, the proportion of the acid-modified product is preferably 10% by mass or more, more preferably 20% by mass or more, even more preferably 30% by mass or more, and most preferably 40% by mass or more, from the viewpoint of effectively obtaining the toughness-improving effect of the elastomer of this embodiment. The upper limit of the proportion of the acid-modified product is not particularly limited, and the elastomer of this embodiment may be composed essentially of the acid-modified product alone. However, from the viewpoint of avoiding problems with the flowability of the resin composition, it is desirable for the proportion to be 80% by mass or less.

[0046] From the viewpoint of compatibility with polyamide, the amount of acidic functional groups in the acid-modified product is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, even more preferably 0.2% by mass or more, and preferably 5% by mass or less, more preferably 3% by mass or less, even more preferably 2% by mass or less. The number of acidic functional groups is a value obtained by measuring a calibration curve sample, which has been mixed with an acidic substance in advance, using an infrared absorption spectrometer and measuring the sample based on a calibration curve prepared using the characteristic absorption band of the acid.

[0047] In one aspect, the amount of acidic functional groups relative to 100% by mass of the total amount of the elastomer of this embodiment is preferably within the range exemplified above as the amount of acidic functional groups in the acid-modified product.

[0048] In one aspect, a value X obtained by multiplying the amino group terminal concentration [NH2] (mmol / g) of the polyamide by the content (mass%) of the polyamide in the resin composition; The value Y obtained by multiplying the acidic functional group concentration (mmol / g) of the polymer having an acidic functional group by the content (mass%) of the polymer having an acidic functional group in the resin composition is calculated using the following formula: 10≦X / Y≦50 It is preferable that the following relationship is satisfied. From the viewpoint of improving the breaking strain, the X / Y ratio is preferably 10 or more, more preferably 12 or more, even more preferably 14 or more, and most preferably 16 or more, and from the viewpoint of moldability, it is preferably 50 or less, more preferably 40 or less, even more preferably 35 or less, and most preferably 25 or less. The acidic functional group concentration is calculated by the following formula using the amount (mass%) of acidic functional groups calculated as described above and the molar mass of the acidic functional groups. Acidic functional group concentration [mmol / g] = ((amount of acidic functional group (mass%) / 100) / molar mass of acidic functional group [g / mol]) × 1000

[0049] The elastomer may be a mixture of an aromatic vinyl compound-conjugated diene compound block copolymer and a hydrogenated product of the aromatic vinyl compound-conjugated diene compound block copolymer, a mixture of an aromatic vinyl compound-conjugated diene compound block copolymer having an acidic functional group and a hydrogenated product of an aromatic vinyl compound-conjugated diene compound block copolymer not having an acidic functional group, a mixture of a hydrogenated product of an aromatic vinyl compound-conjugated diene compound block copolymer having an acidic functional group and an aromatic vinyl compound-conjugated diene compound block copolymer not having an acidic functional group, or a mixture of an aromatic vinyl compound-conjugated diene compound block copolymer having an acidic functional group and a hydrogenated product of an aromatic vinyl compound-conjugated diene compound block copolymer having an acidic functional group. When the total of the aromatic vinyl compound-conjugated diene compound block copolymer and the hydrogenated aromatic vinyl compound-conjugated diene compound block copolymer is taken as 100% by mass, the proportion of the hydrogenated aromatic vinyl compound-conjugated diene compound block copolymer is preferably 5% by mass or more, more preferably 10% by mass or more, even more preferably 15% by mass or more, and most preferably 20% by mass or more, from the viewpoint of obtaining a good toughness-improving effect of the elastomer of this embodiment. The upper limit of the proportion of the hydrogenated aromatic vinyl compound-conjugated diene compound block copolymer is preferably 90% by mass or less, more preferably 70% by mass or less, more preferably 50% by mass or less, even more preferably 40% by mass or less, and most preferably 30% by mass or less, from the viewpoint of suppressing the linear expansion coefficient.

[0050] In the resin composition, the amount of elastomer per 100 parts by mass of polyamide is preferably within the range of 1 to 50 parts by mass. The upper limit is preferably 45 parts by mass, more preferably 40 parts by mass, more preferably 35 parts by mass, even more preferably 30 parts by mass, and most preferably 25 parts by mass. In order to maintain good rigidity and heat resistance of the resin composition, it is desirable to keep the amount below the above-mentioned upper limit. The lower limit is more preferably 2 parts by mass, even more preferably 3 parts by mass, even more preferably 4 parts by mass, and most preferably 5 parts by mass. In order to improve the toughness and physical property stability of the resin composition, it is preferable to keep the amount above the above-mentioned lower limit.

[0051] When the elastomer phase forms a particulate dispersed phase (dispersed particles) in the resin composition, the dispersed particle diameter is preferably 3 μm or less, more preferably 2 μm or less, and most preferably 1 μm or less, as the number average particle diameter. The lower limit is not particularly limited, but is, for example, 0.1 μm. From the viewpoint of high toughness and physical property stability, it is preferable to set it within the above range.

[0052] The elastomer preferably has a high uniformity of dispersed particle size. From this viewpoint, the volume ratio of dispersed particles having a particle size of 1 μm or more to the total dispersed particles of the elastomer is preferably 30% by volume or less. The upper limit is more preferably 25% by volume, even more preferably 20% by volume, even more preferably 15% by volume, and most preferably 10% by volume. In the volume-based dispersed particle size distribution, even if there are only a few coarse particles, the volume ratio of dispersed particles having a particle size of 1 μm or more is suddenly expressed as being large. When the volume ratio is within the above range, the uniformity of the dispersed particle size is high, which is preferable. From the viewpoint of ease of production of the resin composition, the volume ratio may be, for example, 2% by volume or more, or 5% by volume or more.

[0053] One method for improving the uniformity of the dispersed particle size of the elastomer is to produce a resin composition by extrusion kneading the compounding components of the resin composition, and to finely disperse the elastomer by increasing the screw rotation speed during extrusion kneading to impart high shear strain to the compounding components.

[0054] Methods for observing the dispersion morphology include cutting ultrathin sections of a resin composition in the form of a molded product, pellets, etc., staining the polyamide phase with phosphotungstic acid or the like, and then observing them with a transmission electron microscope, or polishing the surface of a resin composition in the form of a molded product, pellets, etc., immersing it in a solvent that selectively dissolves only the elastomer, extracting the elastomer, and observing it with a scanning electron microscope. The obtained image is binarized using an image analyzer, and the diameters of the dispersed particles (at least 500 randomly selected) in the dispersed phase are calculated as equivalent circle diameters. By counting each particle diameter, the number-average particle diameter of the dispersed particles and the volume ratio of particles with a predetermined particle diameter (for example, the above-mentioned particle diameter of 1 μm or more) can be calculated.

[0055] <Cellulose> Next, the cellulose that can be used in this embodiment will be described in detail. The amount of cellulose that can be used in this embodiment is preferably in the range of 0.1 to 30% by mass, when the entire resin composition is taken as 100% by mass. The upper limit is more preferably 25% by mass, even more preferably 20% by mass, and most preferably 15% by mass. The lower limit is more preferably 0.3% by mass, more preferably 0.5% by mass, even more preferably 1% by mass, and most preferably 3% by mass. In order to suppress the thermal expansion coefficient and maintain the stability of physical properties, it is preferable to keep the amount within the above range.

[0056] The cellulose in this embodiment is preferably cellulose nanofibers with a diameter of 50 to 1000 nm and a length (L) / diameter (D) ratio of 30 or more, cellulose nanocrystals with a diameter of 100 nm or less and a length (L) / diameter (D) ratio of less than 30, cellulose microfibers with a diameter of more than 1 μm to 50 μm, or a mixture thereof.

[0057] Examples of cellulose that can be used in this embodiment include natural cellulose and regenerated cellulose. Examples of natural cellulose include wood pulp obtained from woody species (broadleaf or coniferous trees), non-woody pulp obtained from non-woody species (bamboo, hemp-based fibers, bagasse, kenaf, linter, etc.), and purified pulps thereof (purified linters, etc.). Examples of non-woody pulp that can be used include cotton-derived pulp, including cotton linter pulp, hemp-derived pulp, bagasse-derived pulp, kenaf-derived pulp, bamboo-derived pulp, and straw-derived pulp. Examples of cotton-derived pulp, hemp-derived pulp, bagasse-derived pulp, kenaf-derived pulp, bamboo-derived pulp, and straw-derived pulp include cellulose pulped from purified pulp obtained from raw materials such as cotton lint, cotton linter, hemp-based abaca (e.g., from Ecuador or the Philippines), zaisal, bagasse, kenaf, bamboo, and straw, which are subjected to a purification process such as delignification by cooking, followed by a bleaching process.

[0058] The cellulose nanocrystals (hereinafter sometimes referred to as CNC) in this embodiment are crystalline cellulose that remains after the aforementioned pulp is cut and the amorphous portion of the cellulose is dissolved in an acid such as hydrochloric acid or sulfuric acid. The diameter of the CNC is 100 nm or less, preferably 80 nm or less, more preferably 70 nm or less, preferably 3 nm or more, more preferably 5 nm or more, and even more preferably 10 nm or more. The length / diameter ratio (L / D ratio) of the CNC is less than 30, preferably 20 or less, more preferably 15 or less, and even more preferably 10 or less. The L / D ratio is 1 or more, preferably 2 or more, more preferably 4 or more, and even more preferably 5 or more.

[0059] Figure 1 shows a microscopic image of an example of cellulose nanowhiskers (needle-shaped particulate cellulose), and Figure 1(B) is a partially enlarged view of Figure 1(A). It can be seen that all of the cellulose has a needle-shaped crystalline particulate structure, a diameter of 100 nm or less, and an L / D ratio of less than 30.

[0060] Cellulose nanofibers (hereinafter sometimes referred to as CNF) refer to cellulose obtained by treating the above-mentioned pulp with hot water at 100°C or higher to hydrolyze and weaken the hemicellulose portion, and then defibrating the cellulose using a pulverizing method such as a high-pressure homogenizer, microfluidizer, ball mill, or disc mill. The diameter of the CNF is 50 to 1,000 nm. The diameter of the CNF is preferably 50 nm or more, more preferably 100 nm or more, more preferably 400 nm or less, and even more preferably 200 nm or less. The L / D ratio of the CNF is 30 or more, preferably 50 or more, more preferably 80 or more, and even more preferably 100 or more, and is preferably 5,000 or less, more preferably 4,000 or less, and even more preferably 3,000 or less.

[0061] Figure 2 is a microscopic image showing examples of cellulose nanofibers. It can be seen that all celluloses have a fibrous structure, a diameter of 50 to 1000 nm, and an L / D ratio of 30 or more.

[0062] Cellulose microfibers (hereinafter sometimes referred to as CMF) refer to relatively large fibrous cellulose obtained by reducing the number of defibration steps in the CNF production process. The diameter of CMF is greater than 1 μm and less than 50 μm. The diameter of CMF is preferably 2 μm or more, more preferably 5 μm or more, even more preferably 10 μm or more, and preferably 45 μm or less, more preferably 40 μm or less, and even more preferably 35 μm or less. The L / D ratio of CMF is preferably 30 or more, more preferably 50 or more, even more preferably 70 or more, and preferably 2000 or less, more preferably 1000 or less, and even more preferably 500 or less. CMF can be obtained with approximately half the energy required to produce regular CNF.

[0063] Figure 3 shows a micrograph of the cellulose microfibers. It can be seen that all of the cellulose has a diameter of more than 1 μm to 50 μm and an L / D ratio of 30 or more.

[0064] In this embodiment, from the viewpoint of ensuring the stability of physical properties, preferred embodiments of the cellulose include the use of CNF alone, the use of CMF alone, the combined use of CNF and CNC, the combined use of CNF and CMF, the combined use of CMF and CNC, and the combined use of CMF, CNF, and CNC. More preferred embodiments include the use of CMF alone, the combined use of CNF and CNC, the combined use of CNF and CMF, the combined use of CMF and CNC, and the combined use of CMF, CNF, and CNC.

[0065] When these two materials are used in combination, the preferred ratio is 50 to 99% by mass of CMF when the total amount of cellulose is 100% by mass. The upper limit of this ratio is more preferably 97% by mass, even more preferably 95% by mass, even more preferably 93% by mass, and most preferably 90% by mass. The lower limit of this ratio is more preferably 55% by mass, even more preferably 60% by mass, and most preferably 70% by mass.

[0066] Furthermore, when CNF and CNC are used in combination, or when CMF and CNC are used in combination, the preferred ratio of CNC is 50 to 99% by mass when the total amount of cellulose is taken as 100% by mass. The upper limit of this ratio is more preferably 97% by mass, even more preferably 95% by mass, even more preferably 93% by mass, and most preferably 90% by mass. The lower limit of this ratio is more preferably 55% by mass, even more preferably 60% by mass, and most preferably 70% by mass.

[0067] Furthermore, when CMF, CNF, and CNC are used in combination, the preferred ratio of CNC is 50 to 99% by mass, where the total amount of cellulose is 100% by mass. The upper limit of this ratio is more preferably 97% by mass, even more preferably 95% by mass, even more preferably 93% by mass, and most preferably 90% by mass. The lower limit of this ratio is more preferably 55% by mass, even more preferably 60% by mass, and most preferably 65% ​​by mass. Furthermore, when the total amount of cellulose other than CNC is 100% by mass, the preferred ratio of CMF is 50 to 99% by mass. The upper limit of this ratio is more preferably 97% by mass, even more preferably 95% by mass, even more preferably 93% by mass, and most preferably 90% by mass. The lower limit of this ratio is more preferably 55% by mass, even more preferably 60% by mass, and most preferably 70% by mass.

[0068] Furthermore, the amount of CMF relative to 100% by mass of the resin composition is preferably 0.1 to 20% by mass. Having the amount of CMF within this range makes it possible to improve properties such as tensile elongation and vibration fatigue characteristics. The lower limit of the amount is more preferably 1% by mass, even more preferably 2% by mass, even more preferably 3% by mass, and most preferably 5% by mass. The upper limit is more preferably 18% by mass, even more preferably 16% by mass, even more preferably 14% by mass, and most preferably 12% by mass.

[0069] In this disclosure, the length, diameter, and L / D ratio of each of CNCs and CNFs are determined by dispersing aqueous dispersions of CNCs and CNFs using a high-shear homogenizer (e.g., Nippon Seiki Co., Ltd., trade name "Excel Auto Homogenizer ED-7") at 15,000 rpm for 5 minutes. The resulting aqueous dispersions are then diluted with pure water to 0.1-0.5% by mass, cast onto mica, and air-dried to obtain measurement samples. These samples are then measured using a high-resolution scanning electron microscope (SEM) or atomic force microscope (AFM). Specifically, the length (L) and diameter (D) of 100 randomly selected cellulose fibers are measured in a field of view adjusted to ensure that at least 100 fibers are visible, and the L / D ratio is calculated. Ratios (L / D) of less than 30 are classified as CNCs, and those of 30 or greater are classified as CNFs. For each of the CNCs and CNFs, the number-average length (L), diameter (D), and L / D ratio are calculated to determine the length, diameter, and L / D ratio of each of the CNCs and CNFs of the present disclosure. The length and diameter of the cellulose of the present disclosure are the number-average values ​​of the 100 cellulose fibers.

[0070] CMFs have a different size scale than CNCs and CNFs, and electron microscopes are not suitable for measuring the length, diameter, and L / D ratio of CMFs. Therefore, CMF size is observed using a different method. A low-concentration aqueous dispersion prepared to contain approximately 0.1% CMF by mass is subjected to sufficient vibration in an ultrasonic cleaner or dispersed for 20 minutes in a disperser (e.g., Despamill, manufactured by Asada Iron Works Co., Ltd.) to loosen the entanglements between the CMFs. The aqueous dispersion is then observed directly under an optical microscope. The measurement and calculation methods used are the same as those for CNFs and CNCs.

[0071] Alternatively, the length, diameter, and L / D ratio of each of the CMF, CNC, and CNF in the resin composition can be measured by dissolving the polymer components in the composition in an organic or inorganic solvent that can dissolve the polymer components of the composition, separating the cellulose, thoroughly washing it with the solvent, and then replacing the solvent with pure water to prepare an aqueous dispersion.The cellulose concentration is then diluted with pure water to 0.1 to 0.5 mass%, and the measurement is performed using the method described above.

[0072] The average diameter of the CNCs measured by volume average particle diameter is preferably 10 nm or more, more preferably 15 nm or more, even more preferably 20 nm or more, and is preferably 1000 nm or less, more preferably 500 nm or less, even more preferably 300 nm or less. The average diameter of the CNFs, as measured by volume average particle diameter, is preferably 20 nm or more, more preferably 40 nm or more, even more preferably 50 nm or more, and is preferably 1000 nm or less, more preferably 700 nm or less, even more preferably 500 nm or less.

[0073] The volume average particle diameter is a value determined by a laser diffraction / scattering particle size distribution analyzer as the equivalent spherical diameter (volume average particle diameter) of particles when the cumulative volume is 50%. Specifically, a sample is mixed at a solid content of 40 mass % in a planetary mixer (e.g., 5DM-03-R, manufactured by Shinagawa Kogyosho Co., Ltd., with a hook-type stirring blade) at 126 rpm under room temperature and normal pressure for 30 minutes, then suspended in pure water at a concentration of 0.5 mass %, dispersed at a rotation speed of 15,000 rpm for 5 minutes using a high-shear homogenizer (e.g., Nippon Seiki Co., Ltd., trade name "Excel Auto Homogenizer ED-7", processing conditions), and centrifuged at a centrifugal force of 39,200 m 2 The supernatant was collected after centrifugation at 116,000 m / s for 10 minutes. 2 The supernatant is centrifuged at 1 / s for 45 minutes, and the supernatant is collected. The volume-average particle size is determined by a volume-frequency particle size distribution obtained using a laser diffraction / scattering particle size distribution analyzer (e.g., HORIBA, Ltd., trade name "LA-910" or trade name "LA-950", ultrasonic treatment for 1 minute, refractive index 1.20). The cumulative 50% particle size (i.e., the spherical equivalent diameter of particles when the cumulative volume is 50% of the total volume of particles) is the volume-average particle size.

[0074] The degree of polymerization of the cellulose (in one embodiment, each of CNC, CNF, and CMF) is preferably 100 or more, or 150 or more, or 200 or more, or 300 or more, or 400 or more, or 450 or more, and preferably 3500 or less, or 3300 or less, or 3200 or less, or 3100 or less, or 3000 or less.

[0075] In the present disclosure, the degree of polymerization of cellulose is the average degree of polymerization measured according to the reduced specific viscosity method using a copper ethylenediamine solution described in confirmation test (3) of the "15th Revised Japanese Pharmacopoeia Manual (published by Hirokawa Shoten)."

[0076] The weight-average molecular weight (Mw) of cellulose (in one embodiment, each of CNC, CNF, and CMF) is preferably 100,000 or more, or 200,000 or more. The ratio (Mw / Mn) of the weight-average molecular weight to the number-average molecular weight (Mn) is preferably 6 or less, or 5.4 or less. A higher weight-average molecular weight indicates a lower number of terminal groups in the cellulose molecule. Furthermore, since the ratio (Mw / Mn) of the weight-average molecular weight to the number-average molecular weight indicates the width of the molecular weight distribution, a lower Mw / Mn indicates a lower number of terminal groups in the cellulose molecule. Since the terminals of cellulose molecules are the starting points for thermal decomposition, particularly high heat-resistant cellulose and resin compositions containing cellulose and a resin can be obtained when the cellulose has not only a high weight-average molecular weight but also a narrow molecular weight distribution. The weight-average molecular weight (Mw) of cellulose may be, for example, 600,000 or less, or 500,000 or less, from the viewpoint of the availability of cellulose raw materials. From the viewpoint of ease of production of cellulose, the ratio of weight-average molecular weight to number-average molecular weight (Mn) (Mw / Mn) may be, for example, 1.5 or more, or 2 or more. Mw can be controlled within the above range by selecting a cellulose raw material having an Mw appropriate for the purpose, or by subjecting the cellulose raw material to appropriate physical and / or chemical treatments within an appropriate range, etc. Mw / Mn can also be controlled within the above range by selecting a cellulose raw material having an Mw / Mn appropriate for the purpose, or by subjecting the cellulose raw material to appropriate physical and / or chemical treatments within an appropriate range, etc. In both Mw and Mw / Mn control, examples of the physical treatment include dry or wet grinding using a microfluidizer, ball mill, or disk mill, or physical treatments that apply mechanical forces such as impact, shear, shear, or friction using a crusher, homomixer, high-pressure homogenizer, or ultrasonic device, etc. Examples of the chemical treatment include digestion, bleaching, acid treatment, and conversion to regenerated cellulose.

[0077] The weight-average molecular weight and number-average molecular weight of cellulose referred to here are values ​​determined by dissolving cellulose in N,N-dimethylacetamide containing lithium chloride and then performing gel permeation chromatography using N,N-dimethylacetamide as a solvent.

[0078] Methods for controlling the degree of polymerization (i.e., average degree of polymerization) or molecular weight of cellulose include hydrolysis treatment. Hydrolysis treatment promotes depolymerization of amorphous cellulose inside cellulose fibers, reducing the average degree of polymerization. At the same time, hydrolysis treatment removes impurities such as hemicellulose and lignin in addition to the amorphous cellulose, making the inside of the fibers porous. This makes the cellulose more susceptible to mechanical treatment in processes that apply mechanical shear force to the cellulose, such as the kneading process described below, and facilitates pulverization of the cellulose.

[0079] The hydrolysis method is not particularly limited, and examples include acid hydrolysis, alkaline hydrolysis, hydrothermal decomposition, steam explosion, and microwave decomposition. These methods may be used alone or in combination. In acid hydrolysis, for example, α-cellulose obtained as pulp from fibrous plants is used as the cellulose raw material. This is dispersed in an aqueous medium, and an appropriate amount of a protonic acid, carboxylic acid, Lewis acid, heteropolyacid, or the like is added. The mixture is then heated with stirring, allowing for easy control of the average degree of polymerization. The reaction conditions, such as temperature, pressure, and time, vary depending on the cellulose species, cellulose concentration, acid species, and acid concentration, but are appropriately adjusted to achieve the desired average degree of polymerization. For example, cellulose may be treated with a mineral acid solution containing 2% or less by weight at 100°C or higher under pressure for 10 minutes or longer. Under these conditions, the acid or other catalyst component penetrates deep into the cellulose fibers, promoting hydrolysis. This allows for a reduction in the amount of catalyst component used, facilitating subsequent purification. The dispersion of the cellulose raw material during hydrolysis may contain, in addition to water, a small amount of an organic solvent within a range that does not impair the effects of the present invention.

[0080] Alkali-soluble polysaccharides that cellulose may contain include hemicellulose, β-cellulose, and γ-cellulose. Alkali-soluble polysaccharides are understood by those skilled in the art as components obtained as the alkali-soluble portion of holocellulose obtained by solvent extraction and chlorine treatment of plants (e.g., wood) (i.e., components obtained by removing α-cellulose from holocellulose). Alkali-soluble polysaccharides are polysaccharides containing hydroxyl groups and have poor heat resistance, which can lead to problems such as decomposition when exposed to heat, yellowing during thermal aging, and a decrease in the strength of cellulose. Therefore, it is preferable that the content of alkali-soluble polysaccharides in cellulose is low.

[0081] In one embodiment, the average content of alkali-soluble polysaccharides in the cellulose (in one embodiment, each of CNC, CNF, and CMF) is preferably 20% by mass or less, 18% by mass or less, 15% by mass or less, or 12% by mass or less, based on 100% by mass of the cellulose, from the viewpoint of obtaining good dispersibility of the cellulose. From the viewpoint of ease of production of the cellulose, the content may be 1% by mass or more, 2% by mass or more, or 3% by mass or more.

[0082] The average alkali-soluble polysaccharide content can be determined by the method described in the non-patent document (Wood Science Experiment Manual, edited by the Japan Wood Research Society, pp. 92-97, 2000), by subtracting the α-cellulose content from the holocellulose content (Wise method). This method is recognized in the industry as a method for measuring hemicellulose content. The alkali-soluble polysaccharide content is calculated three times for each sample, and the number average of the calculated alkali-soluble polysaccharide contents is taken as the average alkali-soluble polysaccharide content.

[0083] In one embodiment, the average content of acid-insoluble components in the cellulose (in one embodiment, each of CNC, CNF, and CMF) is preferably 10% by mass or less, 5% by mass or less, or 3% by mass or less, based on 100% by mass of cellulose, from the viewpoint of avoiding a decrease in heat resistance of the cellulose and the resulting discoloration. From the viewpoint of ease of production of the cellulose, the content may be 0.1% by mass or more, 0.2% by mass or more, or 0.3% by mass or more.

[0084] The average acid-insoluble content is determined by quantifying the acid-insoluble content using the Clason method described in the non-patent document (Wood Science Experiment Manual, edited by the Japan Wood Research Society, pp. 92-97, 2000). This method is recognized in the art as a method for measuring lignin content. A sample is stirred in a sulfuric acid solution to dissolve cellulose, hemicellulose, and other components, and then filtered through a glass fiber filter. The resulting residue corresponds to the acid-insoluble component. The acid-insoluble component content is calculated from the weight of the acid-insoluble component, and the number average of the acid-insoluble component contents calculated for three samples is used as the average acid-insoluble component content.

[0085] <Hydrophobicity of cellulose> The cellulose in this embodiment may be hydrophobized with a hydrophobizing agent. Hydrophobization weakens hydrogen bonds between cellulose molecules, contributing to fine dispersion, improving the heat resistance of the cellulose, making it possible to suppress deterioration due to kneading with resins, and making the cellulose less likely to become a starting point for physical defects, resulting in increased toughness and reduced toughness variation.

[0086] As the hydrophobizing agent, a compound that reacts with the hydroxyl group of cellulose can be used, and examples thereof include an esterifying agent, an etherifying agent, and a silylating agent. Particularly, an esterifying agent is preferred. As the esterifying agent, acid halides, acid anhydrides, carboxylic acid vinyl esters, and carboxylic acids are preferred. That is, as the hydrophobizing agent, esterification is preferred, and acetylation is particularly preferred.

[0087] The acid halide may be at least one selected from the group consisting of compounds represented by the following formula (1): R 1 -C(=O)-X (1) (In the formula, R 1 represents an alkyl group having 1 to 24 carbon atoms, an alkenyl group having 2 to 24 carbon atoms, a cycloalkyl group having 3 to 24 carbon atoms, or an aryl group having 6 to 24 carbon atoms, and X is Cl, Br, or I. Specific examples of acid halides include, but are not limited to, acetyl chloride, acetyl bromide, acetyl iodide, propionyl chloride, propionyl bromide, propionyl iodide, butyryl chloride, butyryl bromide, butyryl iodide, benzoyl chloride, benzoyl bromide, and benzoyl iodide. Among these, acid chlorides are preferred in terms of reactivity and ease of handling. In the reaction of the acid halides, one or more alkaline compounds may be added to act as a catalyst and neutralize acidic by-products. Specific examples of alkaline compounds include, but are not limited to, tertiary amine compounds such as triethylamine and trimethylamine; and nitrogen-containing aromatic compounds such as pyridine and dimethylaminopyridine.

[0088] As the acid anhydride, any appropriate acid anhydride can be used. For example, Saturated aliphatic monocarboxylic acid anhydrides such as acetic acid, propionic acid, (iso)butyric acid, and valeric acid; unsaturated aliphatic monocarboxylic acid anhydrides such as (meth)acrylic acid and oleic acid; Alicyclic monocarboxylic acid anhydrides such as cyclohexanecarboxylic acid and tetrahydrobenzoic acid; Aromatic monocarboxylic acid anhydrides such as benzoic acid and 4-methylbenzoic acid; Examples of dibasic carboxylic acid anhydrides include saturated aliphatic dicarboxylic acid anhydrides such as succinic anhydride and adipic acid, unsaturated aliphatic dicarboxylic acid anhydrides such as maleic anhydride and itaconic anhydride, alicyclic dicarboxylic acid anhydrides such as 1-cyclohexene-1,2-dicarboxylic acid anhydride, hexahydrophthalic anhydride and methyltetrahydrophthalic anhydride, and aromatic dicarboxylic acid anhydrides such as phthalic anhydride and naphthalic anhydride; Examples of the tri- or higher basic carboxylic acid anhydrides include polycarboxylic acid (anhydrides) such as trimellitic anhydride and pyromellitic anhydride. In the reaction of an acid anhydride, one or more of the following may be added as a catalyst: an acidic compound such as sulfuric acid, hydrochloric acid, or phosphoric acid; a Lewis acid (for example, a Lewis acid compound represented by MYn, where M represents a semimetallic element such as B, As, or Ge; a base metal element such as Al, Bi, or In; a transition metal element such as Ti, Zn, or Cu; or a lanthanoid element; n is an integer corresponding to the valence of M and represents 2 or 3; and Y represents a halogen atom, OAc, OCOCF3, ClO4, SbF6, PF6, or OSO2CF3(OTf)); or an alkaline compound such as triethylamine or pyridine.

[0089] The vinyl carboxylate may be selected from the group consisting of vinyl carboxylates represented by the following formula (1): R-COO-CH=CH2…Formula (1) Preferred are vinyl carboxylate esters represented by the formula: {wherein R is any one of an alkyl group having 1 to 24 carbon atoms, an alkenyl group having 2 to 24 carbon atoms, a cycloalkyl group having 3 to 16 carbon atoms, and an aryl group having 6 to 24 carbon atoms.} More preferably, the vinyl carboxylate ester is at least one selected from the group consisting of vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl cyclohexanecarboxylate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, vinyl pivalate, vinyl octylate, divinyl adipate, vinyl methacrylate, vinyl crotonate, vinyl pivalate, vinyl octylate, vinyl benzoate, and vinyl cinnamate. In the esterification reaction with a vinyl carboxylate, one or more catalysts selected from the group consisting of alkali metal hydroxides, alkaline earth metal hydroxides, alkali metal carbonates, alkaline earth metal carbonates, alkali metal hydrogencarbonates, primary to tertiary amines, quaternary ammonium salts, imidazole and derivatives thereof, pyridine and derivatives thereof, and alkoxides may be added.

[0090] Examples of alkali metal hydroxides and alkaline earth metal hydroxides include sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, barium hydroxide, etc. Examples of alkali metal carbonates, alkaline earth metal carbonates, and alkali metal hydrogen carbonates include lithium carbonate, sodium carbonate, potassium carbonate, cesium carbonate, magnesium carbonate, calcium carbonate, barium carbonate, lithium hydrogen carbonate, sodium hydrogen carbonate, potassium hydrogen carbonate, cesium hydrogen carbonate, etc.

[0091] The primary to tertiary amines refer to primary amines, secondary amines, and tertiary amines, and specific examples include ethylenediamine, diethylamine, proline, N,N,N',N'-tetramethylethylenediamine, N,N,N',N'-tetramethyl-1,3-propanediamine, N,N,N',N'-tetramethyl-1,6-hexanediamine, tris(3-dimethylaminopropyl)amine, N,N-dimethylcyclohexylamine, and triethylamine.

[0092] Examples of imidazole and its derivatives include 1-methylimidazole, 3-aminopropylimidazole, and carbonyldiimidazole.

[0093] Examples of pyridine and its derivatives include N,N-dimethyl-4-aminopyridine and picoline.

[0094] Examples of the alkoxide include sodium methoxide, sodium ethoxide, and potassium t-butoxide.

[0095] The carboxylic acid may be at least one selected from the group consisting of compounds represented by the following formula (1). R-COOH …(1) (In the formula, R represents an alkyl group having 1 to 16 carbon atoms, an alkenyl group having 2 to 16 carbon atoms, a cycloalkyl group having 3 to 16 carbon atoms, or an aryl group having 6 to 16 carbon atoms.)

[0096] Specific examples of carboxylic acids include at least one selected from the group consisting of acetic acid, propionic acid, butyric acid, caproic acid, cyclohexanecarboxylic acid, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, pivalic acid, methacrylic acid, crotonic acid, pivalic acid, octylic acid, benzoic acid, and cinnamic acid.

[0097] Among these carboxylic acids, at least one selected from the group consisting of acetic acid, propionic acid, and butyric acid, and particularly acetic acid, is preferred from the viewpoint of reaction efficiency. In the reaction of carboxylic acid, one or more of the following may be added as a catalyst: an acidic compound such as sulfuric acid, hydrochloric acid, or phosphoric acid; a Lewis acid (for example, a Lewis acid compound represented by MYn, where M represents a semimetallic element such as B, As, or Ge; a base metal element such as Al, Bi, or In; a transition metal element such as Ti, Zn, or Cu; or a lanthanoid element; n is an integer corresponding to the valence of M and represents 2 or 3; and Y represents a halogen atom, OAc, OCOCF3, ClO4, SbF6, PF6, or OSO2CF3(OTf)); or an alkaline compound such as triethylamine or pyridine.

[0098] Among these esterification reactants, at least one selected from the group consisting of acetic anhydride, propionic anhydride, butyric anhydride, vinyl acetate, vinyl propionate, vinyl butyrate, and acetic acid, and among these, acetic anhydride and vinyl acetate are preferred from the viewpoint of reaction efficiency.

[0099] The degree of modification of the chemically modified cellulose of this embodiment is expressed as the average degree of hydroxyl substitution (the average number of hydroxyl groups substituted per glucose, the basic structural unit of cellulose, also referred to as DS). In one aspect, the DS of the chemically modified cellulose is preferably 0.01 or more and 2.0 or less. A DS of 0.01 or more allows for the production of a resin composition containing chemically modified cellulose with a high thermal decomposition onset temperature. On the other hand, a DS of 2.0 or less allows for the production of a resin composition containing chemically modified cellulose that combines the high tensile strength and dimensional stability inherent in cellulose with the high thermal decomposition onset temperature inherent in chemical modification, since the unmodified cellulose skeleton remains in the chemically modified cellulose. DS is more preferably 0.05 or more, or 0.1 or more, or 0.2 or more, or 0.3 or more, and more preferably 1.8 or less, or 1.5 or less, or 1.2 or less, or 1.0 or less.

[0100] When the modifying group of chemically modified cellulose is an acyl group, the degree of acyl substitution (DS) can be calculated from the peak intensity ratio of the peak derived from the acyl group to the peak derived from the cellulose skeleton in the reflection infrared absorption spectrum of the esterified cellulose. The peak of the absorption band of C=O derived from the acyl group is at 1730 cm. -1 The absorption band of CO based on the cellulose backbone appears at 1030 cm -1 The DS of esterified cellulose is determined by creating a correlation graph between the DS obtained from solid-state NMR measurements of esterified cellulose (described below) and the modification rate (IR index 1030), which is defined as the ratio of the peak intensity of the absorption band of C=O based on the acyl group to the peak intensity of the absorption band of CO in the cellulose backbone chain, and then calculating the calibration curve from the correlation graph. Degree of substitution DS = 4.13 × IR index (1030) It can be found by using

[0101] The method for calculating the DS of esterified cellulose by solid-state NMR is as follows: 13C solid-state NMR measurements were performed, and the chromaticity can be calculated using the following formula, which is the ratio of the chromatic intensity (Inf) of a signal assigned to one carbon atom derived from the modifying group to the total chromatic intensity (Inp) of signals assigned to carbons C1-C6 derived from the pyranose ring of cellulose, which appear in the range from 50 ppm to 110 ppm. DS=(Inf)×6 / (Inp) For example, when the modifying group is an acetyl group, the signal at 23 ppm assigned to -CH3 can be used. Use 13 The conditions for the C solid-state NMR measurement are, for example, as follows: Equipment:Bruker Biospin Avance500WB Frequency: 125.77MHz Measurement method: DD / MAS method Waiting time: 75 seconds NMR sample tube: 4mmφ Accumulation times: 640 times (approx. 14 hours) MAS: 14,500Hz Chemical shift reference: glycine (external reference: 176.03 ppm)

[0102] <Conductive carbon-based filler> In a preferred embodiment, the resin composition further contains a conductive carbonaceous filler. This allows for the production of a conductive resin composition. Preferred conductive carbonaceous fillers include carbon black, carbon fiber, graphite, graphene, and carbon nanotubes. These conductive carbonaceous fillers may be in the form of granules, flakes, or fibers. Specific examples of preferred conductive carbonaceous fillers include conductive carbon black, carbon nanotubes (CNTs), carbon fiber, and graphite. Of these, conductive carbon black and CNTs are most preferred.

[0103] The dibutyl phthalate (DBP) absorption of the conductive carbon black is preferably 250 ml / 100 g or more, more preferably 300 ml / 100 g or more, and even more preferably 350 ml / 100 g or more. The DBP absorption here is a value measured by the method specified in ASTM D2414. Furthermore, the conductive carbon black should have a BET surface area of ​​200 m 2 / g or more is preferable, and 400m 2 / g or more is more preferable. Commercially available conductive carbon blacks include Ketjenblack EC-600JD and the like.

[0104] The conductive carbon black in this embodiment is a general coloring carbon black (usually having the above-mentioned DBP absorption of less than 250 ml / 100 g and a BET surface area of ​​200 m 2 / g), good conductivity is achieved with a small amount of addition.

[0105] Carbon nanotubes (CNTs) are carbon-based fibers with a fiber diameter of 100 nm or less and a hollow structure. CNTs include both single-walled carbon nanotubes, whose tube walls are made of a single layer of carbon, and multi-walled nanotubes, whose tube walls are made of multiple layers of carbon.

[0106] The conductive carbonaceous filler may be treated with any of various known coupling agents and / or sizing agents to improve adhesion to the resin and / or ease of handling.

[0107] The amount of the conductive carbonaceous filler is preferably 0.1 to 10% by mass, assuming the entire resin composition to be 100% by mass. The upper limit is more preferably 8% by mass, even more preferably 6% by mass, and most preferably 3% by mass. The lower limit is more preferably 0.3% by mass, even more preferably 0.5% by mass, and most preferably 0.8% by mass. In order to maintain a stable balance between the conductivity and fluidity of the resin composition, it is desirable to keep the amount within the above range.

[0108] <Aggregation inhibitor> Since cellulose tends to aggregate during the drying process and is difficult to redisperse, it is preferable to use an aggregation inhibitor to improve the redispersibility of cellulose when melt-kneaded with a resin. By improving the redispersibility, the mechanical properties and stability of the resulting resin composition can be improved. The aggregation inhibitor is preferably added to an aqueous cellulose dispersion, which is then dried under shear to obtain a cellulose powder.

[0109] The amount of the aggregation inhibitor is preferably 2 to 100 parts by mass per 100 parts by mass of cellulose. The lower limit is more preferably 4 parts by mass, even more preferably 5 parts by mass, and most preferably 6 parts by mass. The upper limit is more preferably 80 parts by mass, even more preferably 60 parts by mass, and most preferably 40 parts by mass. In order to improve the dispersibility of cellulose in the resin and to enhance the stability of physical properties, it is desirable to keep the amount within the above range.

[0110] The aggregation inhibitor can be at least one selected from the group consisting of surfactants, organic compounds with a boiling point of 100° C. or higher, and resins having a chemical structure that can highly disperse cellulose.

[0111] The surfactant may have a chemical structure in which a moiety having a hydrophilic substituent and a moiety having a hydrophobic substituent are covalently bonded, and any surfactant that is used for various purposes such as food and industrial use can be used. For example, the following surfactants can be used alone or in combination of two or more:

[0112] Any of anionic surfactants, nonionic surfactants, amphoteric surfactants, and cationic surfactants can be used as the surfactant. However, in terms of affinity with cellulose, anionic surfactants and nonionic surfactants are preferred, and nonionic surfactants are more preferred.

[0113] Among the above, surfactants having a polyoxyethylene chain, a carboxyl group, or a hydroxyl group as a hydrophilic group are preferred in terms of affinity with cellulose, polyoxyethylene surfactants (polyoxyethylene derivatives) having a polyoxyethylene chain as a hydrophilic group are more preferred, and nonionic polyoxyethylene derivatives are even more preferred. The polyoxyethylene chain length of the polyoxyethylene derivative is preferably 3 or more, more preferably 5 or more, even more preferably 10 or more, and particularly preferably 15 or more. The longer the chain length, the higher the affinity with cellulose, but in terms of the balance with coatability, the upper limit is preferably 60 or less, more preferably 50 or less, even more preferably 40 or less, particularly preferably 30 or less, and most preferably 20 or less.

[0114] Among the surfactants described above, those with hydrophobic groups such as alkyl ether, alkyl phenyl ether, rosin ester, bisphenol A, β-naphthyl, styrenated phenyl, and hydrogenated castor oil are particularly suitable due to their high affinity with resins. The preferred alkyl chain length (in the case of alkylphenyl, the number of carbon atoms excluding the phenyl group) is preferably 5 or more, more preferably 10 or more, even more preferably 12 or more, and particularly preferably 16 or more. When the resin is a polyolefin, the higher the carbon number, the higher the affinity with the resin, so there is no upper limit, but the upper limit is preferably 30 or less, and more preferably 25 or less.

[0115] Among these hydrophobic groups, those having a cyclic structure or those having a bulky and multifunctional structure are preferred. As those having a cyclic structure, alkylphenyl ether type, rosin ester type, bisphenol A type, β-naphthyl type, and styrenated phenyl type are preferred, and as those having a multifunctional structure, hydrogenated castor oil type is preferred. Among these, rosin ester type and hydrogenated castor oil type are particularly more preferred.

[0116] In addition, organic compounds with a boiling point of 100°C or higher may be effective as non-surfactant dispersion media. Examples of such organic compounds include polyethylene glycol, polypropylene glycol, and organic compounds having a glycerin structure. Furthermore, depending on the type of resin, for example, if the resin is a polyolefin, high-boiling organic solvents such as liquid paraffin and decalin are effective. Furthermore, if the resin is a polar resin such as nylon or polyacetate, it may be effective to use a solvent similar to the aprotic solvent that can be used in producing cellulose, such as dimethyl sulfoxide.

[0117] <Coefficient of variation> In the resin composition of this embodiment, from the viewpoint of eliminating strength defects in the resulting molded article, it is preferable that the coefficient of variation CV of the tensile breaking strength is 10% or less. The coefficient of variation here is expressed as a percentage obtained by dividing the standard deviation (σ) by the arithmetic mean (μ) and multiplying the result by 100, and is a unitless number that represents relative variation. CV = (σ / μ) × 100 Here, μ and σ are given by the following equations:

[0118]

number

[0119] The number of samples (n) used to calculate the coefficient of variation CV of the tensile breaking strength is preferably at least 10 or more, more preferably 15 or more, in order to make it easier to find defects.

[0120] A more preferable upper limit of the coefficient of variation is 9%, even more preferably 8%, more preferably 7%, even more preferably 6%, and most preferably 5%. The lower limit is preferably zero, but from the viewpoint of ease of production, it is preferably 0.1%.

[0121] Localized strength defects in conventional resin molded products are thought to be caused by uneven distribution of fillers, etc., the formation of voids, etc. One method for evaluating the likelihood of these strength defects forming is to conduct tensile tests on multiple test pieces and check the presence or absence of variations in breaking strength and the number of pieces.

[0122] For example, the presence of non-uniformly dispersed filler areas, voids, etc. in molded structural parts such as automobile bodies, door panels, and bumpers can cause stress concentration and lead to fracture when a large, sudden stress is applied to the molded part, or when a small, repeated stress such as vibration is applied. This reduces product reliability. For materials with a homogeneous internal structure and no voids, even when multiple samples are subjected to tensile fracture tests, the stress leading to fracture is nearly identical across the multiple samples, and the coefficient of variation is very small. However, for materials with internal non-uniformities, voids, etc., the stress leading to fracture in one sample will be significantly different from the stress in the other samples. The extent to which such samples exhibit stresses that differ from the stresses of the other samples can be clarified using a measure called the coefficient of variation.

[0123] For example, in the case of a material that does not have a yield strength, a sample with an internal defect will break at a lower strength than other samples. In the case of a material that has a yield strength, after reaching yield, it often breaks on the way to necking, and samples with an internal defect tend to break at a higher strength than other samples. Despite these differences in behavior, the coefficient of variation of tensile breaking strength can be used as a measure to predict the likelihood of strength defects occurring in actual products.

[0124] The coefficient of variation of tensile strength is thought to be significantly affected by the dispersion state and position of cellulose in the composition. In the case of polyamide / elastomer alloys, the elastomer phase and the interface between the elastomer and polyamide are important sites for stabilizing physical properties. For example, if cellulose is localized at the interface between the dispersed phase and the continuous phase or within the dispersed phase, the localized areas become stress concentration points, significantly reducing the stability of physical properties. In other words, stably dispersing cellulose in the polyamide phase increases the stability of physical properties.

[0125] There are various methods for stably dispersing cellulose in a polyamide phase, such as optimizing the composition ratio of polyamide to elastomer, optimizing the amount of acidic functional groups in the elastomer, optimizing the terminal group concentration of the polyamide, optimizing the order of addition during kneading of cellulose, adding an optimal surfactant or the like to weaken the affinity between the elastomer and cellulose or to increase the affinity between the elastomer and polyamide, melt-mixing polyamide and cellulose in advance to form a masterbatch, optimizing the screw configuration during extrusion processing, and optimizing the resin viscosity by controlling the temperature during processing.

[0126] In addition to the above, the heat resistance of cellulose is improved and the cellulose is prevented from becoming the starting point for structural defects due to thermal degradation during kneading with resin, thereby increasing the stability of physical properties.

[0127] Any of these approaches may be adopted to stably disperse cellulose in the polyamide phase. Setting the coefficient of variation (CV) of tensile break strength to 10% or less can significantly contribute to eliminating strength defects in the resulting molded article, and has the effect of significantly improving the reliability of the strength of the molded article.

[0128] The resin composition of this embodiment tends to have a dramatically improved tensile yield strength compared to the thermoplastic resin alone. The ratio of the tensile yield strength of the resin composition to the tensile yield strength of the thermoplastic resin alone, which is taken as 1.0, is preferably 1.1 times or more, more preferably 1.15 times or more, even more preferably 1.2 times or more, and most preferably 1.3 times or more. While there is no particular upper limit to this ratio, from the viewpoint of ease of production, it is preferably 5.0 times, more preferably 4.0 times, for example.

[0129] The resin composition of this embodiment contains cellulose, which allows it to exhibit low thermal expansion without increasing its specific gravity. Specifically, the thermal expansion coefficient of the resin composition in the temperature range of 20°C to 100°C is preferably 60 ppm / K or less, more preferably 50 ppm / K or less, even more preferably 45 ppm / K or less, even more preferably 40 ppm / K or less, and most preferably 35 ppm / K or less. There is no particular lower limit to the thermal expansion coefficient, but from the viewpoint of ease of production, it is preferably 5 ppm / K, more preferably 10 ppm / K, for example.

[0130] The resin composition of this embodiment is characterized in that the cellulose is stably dispersed in the polyamide phase, resulting in small variations in the linear expansion coefficient of a large molded article. This characteristic is particularly pronounced when the polyamide phase is a continuous phase. Specifically, the resin composition exhibits very low variations in the linear expansion coefficient measured using test pieces taken from different parts of the large molded article.

[0131] When cellulose is not uniformly dispersed in a resin composition and the linear expansion coefficient varies greatly from part to part, defects such as distortion or warping of the molded product due to temperature changes are likely to occur. Moreover, this defect is caused by differences in thermal expansion and is a failure mode that occurs reversibly with temperature fluctuations. Therefore, it can be a potentially dangerous failure mode that cannot be detected by checking at room temperature.

[0132] The magnitude of variation in the linear expansion coefficient can be expressed using the coefficient of variation of the linear expansion coefficient of measurement samples obtained from different parts of the body. The coefficient of variation here is calculated in the same way as explained above in the section on the coefficient of variation of the tensile breaking strength.

[0133] The coefficient of variation of the linear expansion coefficient of the resin composition of this embodiment is preferably 15% or less. The upper limit of the coefficient of variation is more preferably 13%, even more preferably 11%, even more preferably 10%, even more preferably 9%, and most preferably 8%. The lower limit is preferably zero, but from the viewpoint of ease of production, it is preferably 0.1%.

[0134] The number of samples (n) used to calculate the coefficient of variation of the linear expansion coefficient is preferably at least 10 to reduce the influence of data errors and the like.

[0135] <Antioxidants> The resin composition of this embodiment may contain an antioxidant as an additional component. The inclusion of an antioxidant in the resin composition of this embodiment is advantageous in that it suppresses thermal degradation of the saponified ethylene-vinyl ester copolymer when the resin composition containing the saponified ethylene-vinyl ester copolymer is melt-kneaded at a high temperature equal to or higher than the melting point of the polyamide. Examples of antioxidants include hindered phenol-based antioxidants, hindered amine-based antioxidants, benzotriazole-based antioxidants, benzophenone-based antioxidants, p-phenylenediamine-based antioxidants, phosphorus-based antioxidants, and sulfur-based antioxidants. Among these, hindered phenol-based antioxidants and phosphorus-based antioxidants are preferred.

[0136] <Coloring agent> The resin composition of this embodiment may contain a colorant as an additional component. Among these, organic colorants are advantageous in that they have the effect of improving the toughness of the resin composition. Examples of organic colorants include azine compounds (such as nigrosine), aniline black, cyanine compounds (such as phthalocyanine and naphthalocyanine), porphyrin, perylene, quaterrylene, metal complexes, azo dyes, anthraquinone, squaric acid derivatives, and immonium dyes, with nigrosine being particularly preferred. Nigrosine is a component known to those skilled in the art as a black azine condensation mixture, and examples of these include those listed in the Color Index as CISOLVENT BLACK 5 and CISOLVENT BLACK 7. Specific examples of nigrosine include triphenazine oxazine and phenazine azine. Examples of commercially available nigrosine products include Nubian Black PA-9801, Nubian Black PA-9800, and Nubian Black PA-0800 (all available from Orient Chemical Industries Co., Ltd.) Nigrosine not only functions as a colorant, but also has the effect of delaying the crystallization of polyamide during the production of the resin composition, particularly during cooling after melt-kneading, and therefore can improve the toughness of the resin composition and suppress the occurrence of defects, thereby reducing variation in the toughness of the resin composition.

[0137] The content of nigrosine in 100% by mass of the resin composition is preferably 0.001% by mass or more, or 0.01% by mass or more, or 0.03% by mass or more, from the viewpoint of obtaining the above-mentioned effects by using nigrosine well, and is preferably 1% by mass or less, or 0.5% by mass or less, or 0.3% by mass or less, from the viewpoint of dimensional stability.

[0138] The resin composition of this embodiment may contain other additives, such as elastomer components other than the elastomer of this embodiment (i.e., the aromatic vinyl compound-conjugated diene compound block copolymer and / or its derivatives); fine fiber filler components made of highly heat-resistant organic polymers other than cellulose (e.g., fibrillated aramid fibers or fine fibers); compatibilizers; plasticizers; polysaccharides such as starches and alginic acid; natural proteins such as gelatin, glue, and casein; inorganic compounds such as zeolites, ceramics, talc, silica, metal oxides, and metal powders; colorants; fragrances; pigments; flow control agents; leveling agents; conductive agents; antistatic agents; UV absorbers; UV dispersants; and deodorizers. The content of these optional additives in the resin composition may be appropriately selected within a range that does not impair the desired effects of the present invention.

[0139] The resin composition of this embodiment can be provided in various shapes. Specific examples include resin pellets, sheets, fibers, plates, rods, and the like. However, resin pellets are preferred due to ease of post-processing and transportation. Preferred pellet shapes include round, oval, and cylindrical shapes, which vary depending on the cutting method used during extrusion. Pellets cut using a cutting method known as underwater cutting are often round, while pellets cut using a cutting method known as hot cutting are often round or oval, and pellets cut using a cutting method known as strand cutting are often cylindrical. For round pellets, the preferred size is a pellet diameter of 1 mm or more and 3 mm or less. For cylindrical pellets, the preferred diameter is 1 mm or more and 3 mm or less, and the preferred length is 2 mm or more and 10 mm or less. The above diameter and length are preferably set to be equal to or greater than the lower limit from the viewpoint of operational stability during extrusion, and are preferably set to be equal to or less than the upper limit from the viewpoint of ease of insertion into a molding machine during post-processing.

[0140] The resin composition of this embodiment can be used as various resin molded articles. There are no particular limitations on the method for producing the resin molded article, and any method may be used, including injection molding, extrusion molding, blow molding, inflation molding, and foam molding. Of these, injection molding is most preferred from the standpoints of design and cost.

[0141] There are no particular limitations on the method for producing the resin composition of the present embodiment, but specific examples include the following methods.

[0142] Examples of such methods include a method in which a mixture of polyamide, elastomer, and cellulose is melt-kneaded using a single-screw or twin-screw extruder, extruded into a strand, and cooled and solidified in a water bath to obtain a pellet-like molded product; a method in which the mixture is melt-kneaded in the same manner using a single-screw or twin-screw extruder, extruded into a rod or cylindrical shape, and cooled to obtain an extrusion molded product; and a method in which the mixture is melt-kneaded using a single-screw or twin-screw extruder, and extruded through a T-die to obtain a sheet- or film-like molded product.

[0143] The resin composition of the present embodiment not only has high toughness and low linear expansion and high fluidity suitable for use in large parts, but also gives a molded article that is substantially free of partial strength defects, and therefore can be suitably used for various large part applications. [Example]

[0144] The present invention will be further explained based on examples, but the present invention is not limited to these examples.

[0145] [Ingredients and evaluation method] The raw materials used and the evaluation methods are described below.

[0146] <Polyamide> Carboxy-terminated polyamide 6 (hereinafter simply referred to as PA6-1) UBE Nylon 1013B (Ube Industries, Ltd.) Amino group terminal concentration [NH2] = 0.046 mmol / g Carboxylic acid end concentration [COOH] = 0.065 mmol / g The amino end group ratio is ([NH2] / ([NH2]+[COOH]))=0.4 Viscosity number (VN) of polyamide measured in 96% by mass sulfuric acid = 95 Amino-terminated polyamide 6 (hereinafter simply referred to as PA62) UBE Nylon 1013A (Ube Industries, Ltd.) Amino group terminal concentration [NH2] = 0.097 mmol / g Carboxy group terminal concentration [COOH] = 0.025 mmol / g The amino end group ratio is ([NH2] / ([NH2]+[COOH]))=0.8 Viscosity number (VN) of polyamide measured in 96% by mass sulfuric acid = 95

[0147] <Elastomer> <Elastomers with acidic functional groups> Tufprene T912 (Asahi Kasei Corporation) (hereinafter simply referred to as m-SBS) Maleic anhydride modified styrene-butadiene-styrene block copolymer Bound styrene content = 40% by mass Maleic anhydride addition rate = 0.2 mass% (0.020 mmol / g) Tuftec M1913 (Asahi Kasei Corporation) (hereinafter simply referred to as m-SEBS) Hydrogenated maleic anhydride-modified styrene-butadiene-styrene block copolymer Bound styrene content = 30% by mass Maleic anhydride addition rate = 1.0 mass% (0.10 mmol / g) Fusabond MN-493D (DowDuPont) (hereinafter referred to simply as m-EOR) Maleic anhydride modified ethylene-octene copolymer MFR(190℃, 2.16kgf)=1.2g / 10min Octene content = 28% by mass Melting point: 55°C (DSC method: heating rate 10°C / min) Maleic anhydride addition rate = 1.0 mass% (0.10 mmol / g) <Elastomer without acidic functional groups> Asaprene T-411 (Asahi Kasei Corporation) (hereinafter simply referred to as SBS) Styrene-butadiene-styrene block copolymer Bound styrene content = 30% by mass

[0148] <Antioxidants> Irganox 1010 (BASF Japan Ltd.) was used. <Coloring agent> Organic colorant: NUBIANBLACK PA9801 (Orient Chemical Industry Co., Ltd.) Inorganic colorant: Carbon black #52 (Mitsubishi Chemical Holdings Corporation)

[0149] <Cellulose> [Preparation Example 1] Hydrophobized CNF (hereinafter referred to as hydrophobized CNF) (defibration process) The linter pulp was mixed in dimethyl sulfoxide (DMSO) at room temperature for 1 hour at 500 rpm using a single-shaft mixer (Imex DKV-1 φ125 mm dissolver). The mixture was then fed to a bead mill (Imex NVM-1.5) using a hose pump and circulated for 120 minutes using only DMSO to obtain a defibrated slurry.

[0150] (Defibrillation and acetylation process) Then, 11 parts by mass of vinyl acetate and 1.63 parts by mass of sodium bicarbonate were added to 100 parts by mass of the defibrated slurry into the bead mill device, and the device was further circulated for 60 minutes to obtain a hydrophobic CNF slurry.

[0151] During circulation operation, the rotation speed of the bead mill was 2500 rpm and the peripheral speed was 12 m / s. The beads used were made of zirconia and had a diameter of 2.0 mm, with a filling rate of 70% (the slit gap of the bead mill at this time was 0.6 mm). During circulation operation, the slurry temperature was controlled at 40°C using a chiller to absorb heat generated by friction.

[0152] To the obtained hydrophobic CNF slurry, 192 parts by mass of pure water was added per 100 parts by mass of defibrated slurry, and after thorough stirring, the mixture was placed in a dehydrator and concentrated. The obtained wet cake was again dispersed in the same amount of pure water, stirred, and concentrated, and this washing procedure was repeated a total of five times.

[0153] The properties of the obtained hydrophobic CNF (wet cake) were evaluated, and it was found that the diameter was 65 nm, the L / D was 30 or more (approximately 450), the weight average molecular weight (Mw) was 340,000, and the degree of acetylation was 0.9.

[0154] To the obtained aqueous dispersion of hydrophobic CNF (solid content: 10% by mass), 5 parts by mass of PEG20000 was added per 100 parts by mass of hydrophobic CNF, and then the mixture was vacuum dried at approximately 40°C using a revolution-rotation type mixer (EME V-mini300) to obtain hydrophobic CNF powder.

[0155] Evaluation Method <Preparation of porous sheet> First, the wet cake was added to tert-butanol, and further dispersed using a mixer or the like until no aggregates were present. The concentration was adjusted to 0.5% by mass per 0.5 g of cellulose solids. 100 g of the resulting tert-butanol dispersion was filtered on filter paper, dried at 150°C, and then the filter paper was peeled off to obtain a sheet. The air resistance of this sheet was 10 g / m2. 2 The porous sheet with a permeability of 100 sec / 100 ml or less was used as the measurement sample. The air resistance is measured by the basis weight W (g / m) of the sheet after leaving it for one day in an environment of 23°C and 50% RH. 2 After measuring the air permeability, the air permeability resistance R (sec / 100 ml) was measured using an Oken type air permeability resistance tester (manufactured by Asahi Seiko Co., Ltd., model EG01). At this time, the air permeability resistance R was calculated according to the following formula: 2 The value per unit area was calculated. Weight 10g / m 2 Air resistance per unit (sec / 100ml) = R / W x 10

[0156] <Weight average molecular weight (Mw) of hydrophobic CNF> 0.88 g of the porous sheet was weighed, chopped into small pieces with scissors, gently stirred, and then 20 mL of pure water was added and left for one day. The water and solids were then separated by centrifugation. 20 mL of acetone was then added, gently stirred, and left for one day. The acetone and solids were then separated by centrifugation. 20 mL of N,N-dimethylacetamide was then added, gently stirred, and left for one day. The N,N-dimethylacetamide and solids were then separated again by centrifugation. 20 mL of N,N-dimethylacetamide was then added, gently stirred, and left for one day. The N,N-dimethylacetamide and solids were then separated by centrifugation. 19.2 g of N,N-dimethylacetamide solution containing 8% lithium chloride by mass was added to the solids, stirred with a stirrer, and visually confirmed to be dissolved. The cellulose-dissolved solution was filtered through a 0.45 μm filter, and the filtrate was used as a sample for gel permeation chromatography. The equipment and measurement conditions used are as follows. Equipment: Tosoh HLC-8120 Column: TSKgel SuperAWM-H (6.0 mm I.D. x 15 cm) x 2 Detector: RI detector Eluent: N,N-dimethylacetamide (lithium chloride 0.2%) Flow rate: 0.6mL / min Calibration curve: pullulan equivalent

[0157] <Degree of acetylation of hydrophobic CNF> The infrared spectrum of the porous sheet was measured by the ATR-IR method at five points using a Fourier transform infrared spectrophotometer (FT / IR-6200 manufactured by JASCO) under the following conditions. Accumulation times: 64 times, Wavenumber resolution: 4cm -1 , Measurement wavenumber range: 4000 to 600 cm -1 , ATR crystal: diamond, Incident angle: 45° From the obtained IR spectrum, the IR index was calculated using the following formula (1): IR index = H1730 / H1030 (1) In the formula, H1730 and H1030 are the values ​​at 1730 cm -1 , 1030cm -1 (absorption band of CO stretching vibration of cellulose backbone chain) -1 and 1500cm -1 The line connecting the -1 and 1500cm -1 The line connecting these points is taken as the baseline, and the absorbance is calculated when this baseline is taken as 0. The average degree of substitution at each measurement point was calculated from the IR index according to the following formula (2), and the average value was taken as DS. DS = 4.13 × IR index (2)

[0158] <Length, diameter, L / D of hydrophobic CNF> The wet cake was suspended in pure water at a concentration of 1% by mass, and dispersed using a high-shear homogenizer (manufactured by Nippon Seiki Co., Ltd., trade name "Excel Auto Homogenizer ED-7", processing conditions: rotation speed 15,000 rpm x 5 minutes). This aqueous dispersion was diluted with pure water to 0.1 to 0.5% by mass, cast on mica, and air-dried. The length (L) to diameter (D) ratio (L / D) of the particle image obtained when measured with an atomic force microscope (AFM) was determined, and this was calculated as the average value for 100 to 150 particles.

[0159] <Confirmation of the continuous phase> The pellets obtained were immersed in chloroform to check for any change in shape. Since no particular change occurred in either the Examples or Comparative Examples, it was determined that the polyamide formed a continuous phase.

[0160] <Polyamide phase ratio of cellulose> The resulting composition was sliced ​​into 1 μm thick films using an ultramicrotome, which were then immersed in chloroform to elute the elastomer phase. The eluate was concentrated and ultracentrifuged to separate the cellulose, which was then washed with chloroform and subjected to three rounds of ultracentrifugation. The remaining cellulose was dried and used to determine the amount of cellulose present in the elastomer phase. This amount was subtracted from the initial amount, and the resulting ratio, divided by the initial amount of cellulose, was expressed as a percentage and used as the polyamide phase ratio of cellulose.

[0161] <Number average particle size of dispersed elastomer particles and volume ratio of dispersed particles with a particle size of 1 μm or more> The resulting composition was photographed using a transmission electron microscope. The number average diameter (i.e., dispersed particle diameter) of 500 dispersed particles in the dispersed elastomer phase and the volume ratio of dispersed particles with a particle diameter of 1 μm or more were calculated.

[0162] <Thermal expansion (coefficient of thermal expansion)> The pellets were melted for 2 minutes in a batch-type twin-screw kneader (DSM Explore) at 250°C and 200 rpm, and then a test piece (ISO 37 type 3) was prepared using a dedicated benchtop injection molding machine (DSM) at a mold temperature of 80°C. A sample measuring 10 mm in length, 4 mm in width, and 2 mm in thickness was cut from the center of the test piece using a precision cutting saw. The expansion coefficient in the direction of resin flow during molding (MD direction, the length direction of the sample) was measured over a temperature range of -10 to 120°C, and the coefficient of thermal expansion (CTE) between 20°C and 100°C was calculated. MD Prior to the measurement, the sample was left to stand in an environment of 120°C for 5 hours to perform annealing.

[0163] <Toughness Tensile strain at break> The pellets were melted for 2 minutes in a batch-type twin-screw mixer (DSM Explore) at 250°C and 200 rpm, and test specimens (ISO 37 type 3) were prepared using a dedicated benchtop injection molding machine (DSM) at a mold temperature of 80°C. Tensile tests were conducted using the test specimens at a tension rate of 5 mm / min in an environment of 23°C and 50% relative humidity, and the arithmetic average of five data points of strain at tensile break was used as an index of toughness.

[0164] <Extrusion conditions> <Extruder Design> Cylinder 1 of the twin-screw extruder (TEM SX series extruder manufactured by Toshiba Machine Co., Ltd.) with 13 cylinder blocks and an L / D of 52 was water-cooled, cylinders 2 to 4 were set to 150°C, and cylinder 5 to the die were set to 250°C. A vent port for reducing pressure and suction was installed in cylinder 12, allowing volatile components and coexisting air to be removed.

[0165] The screw configuration was as follows: cylinders 1 and 2 were used as conveying screws; cylinder 3 was equipped with three clockwise kneading discs (feed-type kneading discs, hereinafter sometimes referred to as RKDs) to form a pre-mixing zone; cylinder 4 was used as a conveying screw; cylinders 5 and 6 were equipped with one RKB, two neutral kneading discs (non-conveying type kneading discs, hereinafter sometimes referred to as NKDs), and a counterclockwise screw to form a melt-kneading zone. Cylinders 7 to 9, which constituted the side feed zone, were used as conveying screws; cylinder 10 was equipped with two RKBs, three NKBs, and a counterclockwise screw to form a kneading zone. Cylinders 11 to 13 were used as conveying screws and formed a devolatilization zone. A die with two 3 mm diameter holes was attached.

[0166] <Production of resin composition> [Examples 1 to 12, Comparative Examples 1 and 2] Using an extruder of the same design, the materials were mixed in the proportions shown in Tables 1 and 2, melt-kneaded at a screw rotation speed of 300 rpm, and pelletized. Various evaluations were then carried out. The results are shown in Tables 1 and 2. The column in the table showing parts by mass indicates the preparation recipe, the middle column showing mass % indicates the composition, and the bottom column shows the physical properties.

[0167] Comparative Example 3 Using an extruder with an extruder design, 20 parts by mass of m-SBS, 7.8 parts by mass of hydrophobized cellulose, and 2 parts by mass of an antioxidant were mixed and melt-kneaded at a screw rotation speed of 300 rpm to form pellets. 29.8 parts by mass of the resulting pellets were melt-kneaded with 80 parts by mass of PA-1 at a screw rotation speed of 300 rpm to obtain pellets, which were then subjected to various evaluations.

[0168] Comparative Example 4 Using an extruder with an extruder design, 20 parts by weight of m-SBS, 7.8 parts by weight of hydrophobized cellulose, 2 parts by weight of antioxidant, and 20 parts by weight of PA-1 were mixed and melt-kneaded at a screw rotation speed of 300 rpm to form pellets. 49.8 parts by weight of the resulting pellets were melt-kneaded with 60 parts by weight of PA-1 at a screw rotation speed of 300 rpm to obtain pellets, which were then subjected to various evaluations.

[0169] [Example 13] Using an extruder with an extruder design, 20 parts by weight of m-SBS, 7.8 parts by weight of hydrophobized cellulose, 2 parts by weight of antioxidant, and 40 parts by weight of PA-1 were mixed and melt-kneaded at a screw rotation speed of 300 rpm to form pellets. 69.8 parts by weight of the resulting pellets were melt-kneaded with 40 parts by weight of PA-1 at a screw rotation speed of 300 rpm to obtain pellets, which were then subjected to various evaluations.

[0170] [Example 14] Using an extruder with an extruder design, 20 parts by weight of m-SBS, 7.8 parts by weight of hydrophobized cellulose, 2 parts by weight of antioxidant, and 60 parts by weight of PA-1 were mixed and melt-kneaded at a screw rotation speed of 300 rpm to form pellets. 89.8 parts by weight of the resulting pellets were melt-kneaded with 20 parts by weight of PA-1 at a screw rotation speed of 300 rpm to obtain pellets, which were then subjected to various evaluations.

[0171] The results shown in Tables 1 and 2 show that the Examples using an aromatic vinyl compound-conjugated diene compound block copolymer or an elastomer derived therefrom exhibited high breaking strain (i.e., good toughness) and a low thermal expansion coefficient, whereas Comparative Example 1, which used an ethylene-octene copolymer as the elastomer, exhibited a poor thermal expansion coefficient, and Comparative Example 2, which did not use an elastomer, exhibited a poor breaking strain. Furthermore, when Examples 4, 5, and 6, which used a colorant, were compared with Example 1, which did not use a colorant, Examples 4, 5, and 6 showed higher breaking strains.

[0172] Comparing Example 1 and Example 9, Example 9, which used a mixture of an aromatic vinyl compound-conjugated diene compound block copolymer and a hydrogenated product of an aromatic vinyl compound-conjugated diene compound block copolymer as the elastomer, had a higher breaking strain. Comparing Example 1 and Example 11, Example 11, which used an amino-terminated polyamide as the polyamide, had a higher breaking strain. Comparing Example 1 and Example 12, the breaking strain was higher in Example 1, which used an aromatic vinyl compound-conjugated diene compound block copolymer as the elastomer, rather than a hydrogenated product of an aromatic vinyl compound-conjugated diene compound block copolymer. Comparing Example 1 with Comparative Examples 3, 4, 13, and 14, the improvement in breaking strain and the decrease in linear expansion coefficient were significant when the polyamide phase ratio of CNF was 50% or more.

[0173] [Table 1]

[0174] [Table 2] [Industrial Applicability]

[0175] The resin composition of the present invention achieves a high degree of compatibility between the contradictory properties of high toughness and low thermal expansion, and has sufficient stability of physical properties to withstand practical use. Therefore, the resin composition can be suitably used, for example, in applications requiring high physical properties over a wide temperature range (such as in the field of exterior materials for automobiles, which are large parts).

Claims

1. polyamide, one or more elastomers selected from the group consisting of aromatic vinyl compound-conjugated diene compound block copolymers and derivatives thereof; cellulose, antioxidants, and flocculation inhibitors, A resin composition comprising: the polyamide and the elastomer are phase-separated, more than 50% by weight of the cellulose is present in the polyamide phase; the amount of the elastomer is 1 to 50 parts by mass per 100 parts by mass of the polyamide; the amount of the cellulose is 0.1 to 30% by mass relative to 100% by mass of the resin composition; the elastomer contains an acid-modified product, A resin composition, wherein the cellulose comprises cellulose nanofibers.

2. 2. The resin composition of claim 1, wherein the polyamide forms a continuous phase and the elastomer forms a dispersed phase.

3. 3. The resin composition according to claim 1, wherein the polyamide is at least one selected from the group consisting of polyamide 6, polyamide 10, polyamide 11, polyamide 12, polyamide 66, polyamide 610, polyamide 612, polyamide 6 / 6I, polyamide 66 / 6I, polyamide 6I, and mixtures thereof.

4. The viscosity number (V) of polyamide measured in 96% by mass sulfuric acid in accordance with ISO 307 N 4. The resin composition according to claim 1, wherein the molecular weight of the polymer is 200 or less.

5. In polyamide, the amino group terminal concentration [NH 2 The ratio of the carboxyl group terminal concentration [NH 2 5. The resin composition according to claim 1, wherein [COOH] / [COOH] is greater than 1.

6. The resin composition according to any one of claims 1 to 5, wherein the amount of the elastomer is 5 to 45 parts by mass per 100 parts by mass of the polyamide.

7. 7. The resin composition according to claim 1, wherein the elastomer is a mixture of a polymer having an acidic functional group and a polymer not having an acidic functional group.

8. The amino group terminal concentration of the polyamide [NH 2 ] (mmol / g) by the content (mass%) of the polyamide in the resin composition; and and a value Y obtained by multiplying the acidic functional group concentration (mmol / g) of the polymer having an acidic functional group by the content (mass%) of the polymer having an acidic functional group in the resin composition, which is expressed by the following formula: 10≦X / Y≦50 The resin composition according to claim 7, which satisfies the following relationship:

9. 9. The resin composition according to claim 1, wherein the elastomer is a mixture of an aromatic vinyl compound-conjugated diene compound block copolymer and a hydrogenated product of the aromatic vinyl compound-conjugated diene compound block copolymer, and one or both of the aromatic vinyl compound-conjugated diene compound block copolymer and the hydrogenated product of the aromatic vinyl compound-conjugated diene compound block copolymer have an acidic functional group.

10. the elastomer is present as dispersed particles in a polyamide continuous phase; The resin composition according to any one of claims 1 to 9, wherein the dispersed particles have a number average particle diameter of 3 µm or less.

11. the elastomer is present as dispersed particles in a polyamide continuous phase; The resin composition according to any one of claims 1 to 10, wherein the dispersed particles have a volume ratio of particles having a particle diameter of 1 µm or more of 30 volume % or less.

12. The resin composition according to any one of claims 1 to 11, wherein the cellulose comprises cellulose nanofibers having a diameter of 50 to 1000 nm and a length (L) / diameter (D) ratio of 30 or more, and further comprises cellulose nanocrystals having a diameter of 100 nm or less and a length (L) / diameter (D) ratio of less than 30, or cellulose microfibers having a diameter of more than 1 μm to 50 μm, or both.

13. The resin composition according to claim 12, wherein the amount of cellulose microfiber is 0.1 to 20% by mass relative to 100% by mass of the resin composition.

14. The resin composition according to any one of claims 1 to 13, wherein the cellulose is hydrophobized cellulose.

15. The resin composition according to any one of claims 1 to 14, further comprising a conductive carbonaceous filler.

16. The resin composition according to any one of claims 1 to 15, further comprising a colorant.

17. The resin composition according to any one of claims 1 to 16, having a thermal expansion coefficient of 60 ppm / K or less at 20°C to 100°C.

18. A molded article made of the resin composition according to any one of claims 1 to 17.

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