JP2020029488A - High-toughness polyamide-cellulose resin composition - Google Patents

Abstract

To provide a resin composition that attains various incompatible characteristics such as low specific gravity, low thermal expansion, low anisotropy and high toughness at the same time and has sufficient physical stability to withstand practical use.SOLUTION: There is provided a resin composition including polyamide, an elastomer and cellulose in which at least a part of the elastomer has an acidic functional group; the polyamide and the elastomer are phase-separated; and more than 50 mass% of the cellulose are present in a polyamide phase.SELECTED DRAWING: None

Description

  The present invention relates to a resin composition containing cellulose, which is excellent in heat resistance and stability of physical properties.

  Since thermoplastic resins are light and have excellent processing characteristics, they are widely used in various fields such as automobile parts, electric / electronic parts, office equipment housings, and precision parts. Particularly in the automobile industry, the replacement of metal members with resin members has been progressing from the past to improve fuel efficiency. In recent years, in regions such as China and Europe, the shift to electric vehicles has begun to be rapidly promoted, and electric vehicles have been actively developed. Therefore, reduction of vehicle weight is becoming an urgent issue in order to extend the cruising distance of electric vehicles. The replacement of metal members with resin members is effective in reducing the weight of automobiles. In particular, the use of resin for exterior components having a large volume greatly contributes to weight reduction, and automobile manufacturers are strengthening their efforts.

  Many polypropylene-based materials are used as resin exterior parts, mainly for bumpers and the like. Further, for a fender as a vertical component, use of a polyamide / polyphenylene ether-based alloy material as described in Patent Literature 1 has been studied in terms of rigidity, heat resistance, and the like. In addition, for the purpose of further improving the dimensional accuracy, for example, Patent Documents 2 and 3 consider mixing inorganic fillers.

International Publication No. 2002/094936 International Publication No. 2006/077818 JP 2006-199748 A

  However, since the rigidity of the polypropylene-based material is not sufficient, it is not suitable for a plate-shaped member (door panel, fender, etc.) among the vertical parts. Further, although the polyamide / polyphenylene ether alloy material can have rigidity that can be used for a fender or the like, there is a problem that the alloy material has a high coefficient of thermal expansion (about 90 ppm / k).

  Cars are expected to run in various driving environments. For example, in a cold place and a desert, the surface temperature difference between components is as high as about 100 ° C. In the case of the coefficient of thermal expansion of the alloy material, for example, when the length of a part having a length of 70 cm is calculated, the dimension changes by about 6 mm. In this case, it is necessary to prepare a gap of several mm in advance in order to avoid contact with adjacent components due to thermal expansion. This is a major challenge for design-oriented passenger cars.

  In order to suppress the thermal expansion coefficient, a technique of blending an inorganic filler is considered. However, the material obtained by this technology, due to the addition of inorganic fillers with high specific gravity, impairs the lightening effect of using resin parts as parts, lowers impact strength, and causes products to warp and anisotropic. Is generated, and furthermore, there is a new problem such as inferior stability of physical properties. Therefore, at present, it has not been widely adopted.

  On the other hand, horizontal parts (for example, hoods, roofs, etc.) of automobiles are large and require further improvement in thermal expansion properties and anisotropy, and replacement of metal members with resin members is not progressing. That is the fact.

  That is, at the present time, there is no material which achieves the contradictory physical properties of low specific gravity, low thermal expansion, low anisotropy, high toughness and high physical stability in a highly balanced manner. An object of the present invention is to solve the above-mentioned problems and to provide a resin composition having simultaneously achieved low specific gravity, low thermal expansion, low anisotropy, high toughness, and high stability in physical properties.

  The present inventors have studied to solve the above-described problems, and as a result of studying, a polyamide as a thermoplastic resin, an elastomer having at least a part having an acidic functional group, and cellulose, and cellulose is mainly contained in a polyamide phase. The present inventors have found that a resin composition which is selectively present can solve the above-mentioned problems, and have accomplished the present invention.

That is, the present invention includes the following embodiments.
[1] A resin composition containing a polyamide, an elastomer, and cellulose,
At least a portion of the elastomer has an acidic functional group,
The polyamide and the elastomer are phase separated,
A resin composition wherein more than 50% by weight 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 polyamide is 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 a mixture thereof. The resin composition according to the above aspect 1 or 2, which is at least one kind.
[4] conforms to ISO 307, 96% strength by weight viscosity number of the polyamide as measured in sulfuric acid (V _N) is 200 or less, the resin composition according to any one of the above embodiments 1-3.
[5] The resin composition according to any one of the above aspects 1 to 4, wherein the amount of the elastomer is 1 to 50 parts by mass with respect to 100 parts by mass of the polyamide.
[6] The elastomer comprises a hydrogenated product of an ethylene-α-olefin copolymer, a block copolymer of an aromatic vinyl compound and a conjugated diene compound, and a block copolymer of an aromatic vinyl compound and a conjugated diene compound. The resin composition according to any one of Aspects 1 to 5, which is at least one member selected from the group.
[7] The resin composition according to any one of the above aspects 1 to 6, wherein the elastomer is an acid anhydride-modified elastomer.
[8] The resin composition according to any one of Aspects 1 to 7, wherein the elastomer is a mixture of an elastomer having an acidic functional group and an elastomer having no acidic functional group.
[9] The elastomer is present as dispersed particles in the polyamide continuous phase,
The resin composition according to any one of Aspects 1 to 8, wherein the dispersed particles have a number average particle diameter of 3 µm or less.
[10] The elastomer is present as dispersed particles in the polyamide continuous phase,
The resin composition according to any of the above aspects 1 to 9, wherein the dispersed particles have a volume ratio of particles having a particle diameter of 1 µm or more and 30% by volume or less.
[11] The resin composition according to any one of the above aspects 1 to 10, wherein the amount of cellulose is 0.1 to 30% by mass relative to 100% by mass of the resin composition.
[12] Cellulose is a cellulose nanofiber having a diameter of 50 to 1000 nm, L / D 30 or more, a cellulose nanocrystal having a diameter of 100 nm or less, less than L / D30, a cellulose microfiber having a diameter of more than 1 μm to 50 μm, or two or more of these The resin composition according to any one of the above aspects 1 to 11, which is a mixture.
[13] The resin composition according to the above aspect 12, wherein the amount of the 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 Embodiments 1 to 13, wherein the cellulose is a hydrophobized cellulose.
[15] The resin composition according to any of aspects 1 to 14, further comprising a conductive carbon-based filler.
[16] The resin composition according to any of aspects 1 to 15, wherein the coefficient of thermal expansion at 20 ° C to 100 ° C is 50 ppm / k or less.
[17] A molded article comprising the resin composition according to any one of the above aspects 1 to 16.

  The resin composition of the present invention has an effect of simultaneously achieving low specific gravity, low thermal expansion, low anisotropy, high toughness, and high physical property stability.

FIG. 1 is a microscope image showing an example of a cellulose nanocrystal. FIG. 2 is a microscope image showing an example of a cellulose nanofiber. FIG. 3 is a microscope image showing an example of a cellulose microfiber. FIG. 4 is a schematic view showing the shape of a fender manufactured for evaluation of the defect rate of the fender in the example and the comparative example. FIG. 5 is a view of a fender showing a position where a test piece is taken out in order to measure a coefficient of variation of a linear expansion coefficient of an actual molded body in Examples and Comparative Examples.

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

  The resin composition of the present invention contains a polyamide, an elastomer, and cellulose. At least a portion of the elastomer has acidic functional groups. The polyamide and the elastomer are phase separated and more than 50% by weight of the cellulose is in the polyamide phase. In a typical embodiment, the resin composition has a two-phase structure of a polyamide phase and an elastomer phase. Although it is not excluded that the resin composition of the present embodiment has three or more phases, a resin composition according to a typical two-phase structure of a polyamide phase and an elastomer phase will be described below. I do.

  The phase morphology of the resin composition of the present embodiment is such that the polyamide forms a continuous phase, the elastomer forms a dispersed phase, the polyamide forms a dispersed phase, the elastomer forms a continuous phase, and the polyamide and the elastomer. Can form a continuous phase (that is, a co-continuous phase structure), but the form in which the polyamide forms the continuous phase and the elastomer forms the dispersed phase provides excellent heat resistance as a composition. This is preferable in terms of increasing rigidity.

  In general, cellulose is considered to have high affinity for, for example, an acid-modified (that is, having an acidic functional group) elastomer and a polyamide because it has hydrophilicity. Further, it is considered that finely divided cellulose may be entangled with a highly viscous elastomer component. In addition, it is known that the location of the cellulose that has been subjected to the hydrophobic treatment as described later in the resin composition changes depending on the kneading conditions due to a decrease in hydrophilicity.

  Among the cellulose in the resin composition of the present embodiment, the lower limit of the proportion of cellulose present in the polyamide phase is more than 50% by mass, preferably 60% by mass, more preferably 70% by mass, Preferably it is 75% by weight, even more preferably 80% by weight and most preferably 100% by weight (ie substantially all the cellulose is present in the polyamide phase). By setting the ratio 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 the ratio may be, for example, 99% by mass or 98% by mass from the viewpoint of ease of production of the resin composition.

  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 content ratio of cellulose is largely different between the polyamide phase and the elastomer phase, the resin composition is not necessarily quantified. It can be easily confirmed by photographing the product with a transmission electron microscope and confirming the amount of cellulose present in the polyamide phase and the amount of cellulose present in the elastomer phase. When quantification is necessary, the resin composition is sliced at a thickness of about 0.1 to 2 μm to obtain a film-like sample. The sample is immersed in a solvent (e.g., chloroform, toluene, etc.) that dissolves the elastomer component but does not dissolve the polyamide, elutes the elastomer phase, concentrates the eluate, performs ultracentrifugation, and presents the sample in the elastomer phase. The cellulose to be separated is separated, and then washed with a solvent at least about three times, dried, and the amount of cellulose present in the elastomer phase is measured.

  Next, each component that can be used in the present embodiment will be described in detail.

<< polyamide >>
Examples of the polyamide used in the present invention include polycondensates of dibasic acids and diamines, cyclic lactam ring-opening polymers, 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, polyamide 612, polymethaxylene adipamide (polyamide MXD6), polyhexamethylene terephthalate Aromatic polyamide resins such as phthalamide (polyamide 6T) and polyhexamethylene isophthalamide (polyamide 6I), and polyamide 6 / 6I, polyamide 66 / 6I, polyamide 6 / 6T, polyamide 66 / 6T, polyamide 6/66 / 6T, polyamide 6/66 / 6I, polyamide 9T, polyamide 10T, and other copolymers and blends. 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 preferably used. . Most preferred are polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 6I, and blends thereof.

  The terminal carboxyl group concentration of the polyamide is not particularly limited, but the lower limit is preferably 20 μmol / g, and more preferably 30 μmol / g. Further, the upper limit of the terminal carboxyl group concentration is preferably 150 μmol / g, more preferably 100 μmol / g, and still more preferably 80 μmol / g.

  In the polyamide, the ratio of the carboxyl terminal group to all terminal groups ([COOH] / [total terminal group]) is preferably 0.30 to 0.95. The lower limit of the carboxyl end group ratio is more preferably 0.35, even more preferably 0.40, and most preferably 0.45. The upper limit of the carboxyl terminal group ratio is more preferably 0.90, still more preferably 0.85, and most preferably 0.80. The carboxyl terminal group ratio is desirably 0.30 or more from the viewpoint of dispersibility of cellulose in the resin composition, and desirably 0.95 or less from the viewpoint of the color tone of the obtained resin composition.

  As a method for adjusting the terminal group concentration of the polyamide, a known method can be used. For example, a diamine compound, a monoamine compound, a dicarboxylic acid compound, a monocarboxylic acid compound, an acid anhydride, a monoisocyanate, a monoacid halide, a monoester, a monoalcohol, etc., so as to have a predetermined terminal group concentration during polymerization of the polyamide. A method in which a terminal adjuster that reacts with a terminal group is added to the polymerization liquid is exemplified.

  Examples of the terminal regulator that reacts with a terminal amino group include 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. Aliphatic 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; A carboxylic acid; and a plurality of mixtures arbitrarily selected from these. Among them, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid are preferred from the viewpoints of reactivity, sealed terminal stability, and price. And at least one terminal adjuster selected from the group consisting of benzoic acid and benzoic acid, and acetic acid is most preferred.

  Examples of a terminal adjuster that reacts with a terminal carboxyl group include aliphatic amines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine. Monoamines; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine, naphthylamine, and any mixtures thereof. Among these, from the viewpoints of reactivity, boiling point, stability of the sealed terminal, price, etc., at least one terminal selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine and aniline. Modifiers are preferred.

The concentration of these amino terminal groups and carboxyl terminal groups is preferably determined from the integrated value of the characteristic signal corresponding to each terminal group by ¹ H-NMR in terms of accuracy and simplicity. As a method for determining the concentration of these terminal groups, a method described in JP-A-7-228775 is specifically recommended. When this method is used, deuterated trifluoroacetic acid is useful as a measuring solvent. Further, the number of times of integration of ¹ H-NMR requires at least 300 scans even when measured by an instrument having a sufficient resolution. In addition, the concentration of the terminal group can be measured by a titration measurement method as described in JP-A-2003-055549. However, in order to minimize the influence of mixed additives, lubricants, and the like, quantification by ¹ H-NMR is more preferable.

The degree of polymerization of the polyamide is not particularly limited, but the viscosity number (V _N ) of the polyamide measured in 96% by mass sulfuric acid in accordance with ISO 307 is 200 or less from the viewpoint of ordinary injection molding processability. It is desirable. A more preferred upper limit is 180, even more preferably 150, even more preferably 140, and most preferably 130. By setting the content within the above range, the fluidity during molding of the molded article is appropriately maintained, and the molding distortion is reduced, whereby the anisotropy of the actual molded article can be suppressed to a low level. The lower limit of the degree of polymerization is not particularly limited, but is preferably 50, more preferably 60, more preferably 65, and most preferably 70, from the viewpoint of obtaining good impact resistance.

  The polyamide in this embodiment may be a mixture of different kinds of polyamides. In the case of a mixture of a plurality of kinds of polyamides, various characteristic values of the polyamide may be an average value of the plurality of kinds.

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

For the purpose of improving the heat stability of the polyamide resin, a known metal-based stabilizer, for example, as described in JP-A-1-163262 may be used. Particularly preferred examples of the metal-based stabilizer include CuI, CuCl ₂ , copper acetate, cerium stearate and the like. Further, a halide salt of an alkali metal represented by potassium iodide, potassium bromide or the like can also be suitably used. These may of course be added in combination. The preferable blending amount of the metal-based stabilizer and / or the alkali metal halide is 0.001 to 5 parts by mass with respect to 100 parts by mass of the polyamide in total. From the viewpoint of heat aging performance, it is preferably at least the above lower limit, and from the viewpoint of maintaining high toughness, it is preferably at most the above upper limit.

  Further, in addition to the above, known additives that can be added to the polyamide may be added in an amount of, for example, less than 10 parts by mass with respect to 100 parts by mass of the polyamide.

<< Elastomer >>
In the present disclosure, an elastomer means a substance that is elastic at room temperature (23 ° C.) (specifically, a natural or synthetic polymer substance). Specific examples of the elastomer include natural rubber, conjugated diene compound polymer, aromatic compound-conjugated diene copolymer, hydrogenated aromatic compound-conjugated diene copolymer, polyolefin, polyester elastomer, polyurethane elastomer, Examples include polyamide-based elastomers and elastomers having a core-shell structure. In one aspect, the elastomer is a different polymer from the polyamide (ie, not a polyamide elastomer). Among them, from the viewpoint of easiness of the acidic functional group modification reaction, aromatic compound-conjugated diene copolymer, aromatic compound-hydrogenated conjugated diene copolymer, polyolefin, and elastomer having a core-shell structure are preferred. preferable. Further, among aromatic compound-conjugated diene copolymers and hydrogenated aromatic compound-conjugated diene copolymers, aromatic compound-conjugated diene block copolymers and aromatic compound-conjugated diene block copolymers can be used. A hydrogenated polymer is more preferable, and among polyolefins, a copolymer of ethylene and an α-olefin is more preferable.

  Here, the aromatic compound-conjugated diene block copolymer refers to a block copolymer composed of a polymer block (A) mainly composed of an aromatic vinyl compound and a polymer block (B) mainly composed of a conjugated diene compound. It is a polymer. A block copolymer in which the bonding type of each block is any of AB type, ABA type, and ABAB type is preferable from the viewpoint of impact strength development, and more preferably, ABA type or ABAB type.

  Further, the mass ratio of the aromatic vinyl compound to the conjugated diene compound in the block copolymer is preferably from 10/90 to 70/30. More preferably, it is 15/85 to 55/45, and most preferably, it is 20/80 to 45/55. Further, two or more of these compounds having different mass ratios of the aromatic vinyl compound and the conjugated diene compound may be blended. Specific examples of the aromatic vinyl compound include styrene, α-methylstyrene, vinyltoluene, and the like. One or more compounds selected from these are used, and styrene is particularly preferred.

  Specific examples of the conjugated diene compound include butadiene, isoprene, piperylene, 1,3-pentadiene and the like, and one or more compounds selected from these are used. Among them, butadiene, isoprene and a combination thereof are preferable. . When using butadiene as the conjugated diene compound of the block copolymer, as a microstructure of the polybutadiene block portion, from the viewpoint of suppressing crystallization of the soft segment, the 1,2-vinyl content, or 1,2-vinyl content. The total amount with the 3,4-vinyl content is preferably from 5 to 80%, more preferably from 10 to 50%, most preferably from 15 to 40% on a molar basis.

  Further, the hydrogenated product of the aromatic vinyl compound and the conjugated diene compound block copolymer is obtained by subjecting the above-described aromatic vinyl compound and the conjugated diene compound block copolymer to a hydrogenation treatment, thereby mainly forming the diene compound. In which the number of aliphatic double bonds in the polymer block is controlled in the range of more than 0% to 100%. The hydrogenation rate of the hydrogenated product of the block copolymer is preferably 50% or more, more preferably 80% or more, and most preferably 98% or more, from the viewpoint of suppressing thermal degradation during processing.

  As the molecular weight of the block copolymer of the aromatic vinyl compound and the conjugated diene compound and the hydrogenated product thereof, the number average molecular weight (Mn) is from 10,000 to from the viewpoint of achieving both impact strength and fluidity. 500,000 are preferred, and 40,000 to 250,000 are most preferred. The number average molecular weight mentioned here is a value measured by conversion with a polystyrene standard at a measurement temperature of 40 ° C. using chloroform as a solvent in a gel permeation chromatography apparatus.

  These aromatic vinyl compound-conjugated diene compound block copolymers have different bonding types, different molecular weights, different aromatic vinyl compound types, different conjugated diene compound types, 1,2-vinyl content. Or, using a mixture of two or more of those having different total amounts of 1,2-vinyl content and 3,4-vinyl content, those having different aromatic vinyl compound component contents, and those having different hydrogenation rates, etc. No problem.

  As the polyolefin, an ethylene-α-olefin copolymer can be preferably used from the viewpoint of the development of impact resistance. Monomers copolymerizable with the ethylene unit include propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, heptene-1, octene-1, nonene-1, decene-1, undecene-1. , Dodecene-1, tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1, heptacene-1, octadecene-1, nonadecene-1, or eicosene-1, aliphatic substituted vinyl monomers such as isobutylene, and styrene , Aromatic vinyl monomers such as substituted styrene, vinyl acetate, acrylates, methacrylates, glycidyl acrylates, glycidyl methacrylates, ester-based vinyl monomers such as hydroxyethyl methacrylate, acrylamide, allylamine , Cycloalkenyl -p- diaminobenzene, nitrogen-containing vinyl monomers such as acrylonitrile, butadiene, may be mentioned dicyclopentadiene, 1,4-hexadiene, and the like dienes such as isoprene.

  It is preferably a copolymer of ethylene and one or more α-olefins having 3 to 20 carbon atoms, more preferably a copolymer of ethylene and one or more α-olefins having 3 to 16 carbon atoms, most preferably ethylene and It is a copolymer with one or more α-olefins having 3 to 12 carbon atoms. Further, the molecular weight of the ethylene-α-olefin copolymer was measured with a gel permeation chromatography measuring apparatus using 1,2,4-trichlorobenzene as a solvent at 140 ° C. and a polystyrene standard from the viewpoint of the development of impact resistance. The number average molecular weight (Mn) is preferably 10,000 or more, more preferably 10,000 to 100,000, and still more preferably 20,000 to 60,000. The molecular weight distribution (weight average molecular weight / number average molecular weight: Mw / Mn) is preferably 3 or less, and more preferably 1.8 to 2.7, from the viewpoint of compatibility between fluidity and impact resistance.

  The preferable content of ethylene units in the ethylene-α-olefin copolymer is 30 to 95% by mass based on the total amount of the ethylene-α-olefin copolymer, from the viewpoint of handleability during processing.

  These preferred ethylene-α-olefin copolymers are described, for example, in Japanese Patent Publication No. 4-12283, JP-A-60-35006, JP-A-60-35007, JP-A-60-35008, It can be manufactured by the manufacturing methods described in Japanese Unexamined Patent Publication No. Hei 5-155930, Japanese Unexamined Patent Publication No. Hei 3-163088, and US Pat. No. 5,272,236.

  In the present disclosure, as the elastomer having a core-shell structure, a core-shell type impact modification having a core which is a particulate rubber and a shell which is a glassy graft layer formed outside the core is provided. Agents. As the rubber component as the core, a butadiene rubber, an acrylic rubber, a silicone-acryl composite rubber, or the like can be preferably used. Further, a glassy polymer such as a styrene resin, an acrylonitrile-styrene copolymer, and an acrylic resin can be suitably used for the shell. Among these, an elastomer having a core-shell structure having a butadiene rubber core and an acrylic resin shell can be suitably used from the viewpoint of compatibility with polyamide.

  In the elastomer of the present embodiment, at least a part of the elastomer has an acidic functional group. In the present disclosure, an elastomer having an acidic functional group means that an acidic functional group is added to the molecular skeleton of the elastomer via a chemical bond. In the present disclosure, the acidic functional group means a functional group capable of reacting with a basic functional group or the like, and specific examples thereof include a hydroxyl group, a carboxyl group, a carboxylate group, a sulfo group, and an acid anhydride group. No.

  The amount of the acidic functional group added in the elastomer is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, and still more preferably 0% by mass or more, based on 100% by mass of the elastomer, from the viewpoint of compatibility with the polyamide. 0.2% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, and still more preferably 2% by mass or less. The number of acidic functional groups is determined based on a calibration curve prepared in advance using a characteristic absorption band of an acid by measuring a calibration curve sample previously mixed with an acidic substance using an infrared absorption spectrum measuring device. This is a value obtained by measuring a sample.

  Examples of the elastomer having an acidic functional group include an elastomer having a core-shell structure having a layer formed by using acrylic acid or the like as a copolymer component, an ethylene-α-olefin copolymer containing acrylic acid or the like as a monomer, a polyolefin, or an aromatic. Α, β-unsaturated dicarboxylic acid or a derivative thereof in the presence or absence of a peroxide on a hydrogenated aromatic compound-conjugated diene copolymer or aromatic compound-conjugated diene copolymer Elastomers, which are modified products, are exemplified.

  In a preferred embodiment, the elastomer is an acid anhydride modified elastomer.

  Among them, polyolefins, aromatic compound-conjugated diene copolymers, or hydrogenated aromatic compound-conjugated diene copolymers may be added to α, β-non-ionic compounds in the presence or absence of peroxides. A modified product obtained by grafting a saturated dicarboxylic acid or a derivative thereof is more preferable, and particularly, the presence of a peroxide in a hydrogenated product of an ethylene-α-olefin copolymer or an aromatic compound-conjugated diene block copolymer is particularly preferable. Particularly preferred is a modified product obtained by grafting α, β-unsaturated dicarboxylic acid and its derivative in the presence or absence thereof.

  Specific examples of the α, β-unsaturated dicarboxylic acid and derivatives thereof include maleic acid, fumaric acid, maleic anhydride, and fumaric anhydride, of which maleic anhydride is particularly preferred.

  It is sufficient that at least a part of the elastomer has an acidic functional group. That is, the elastomer may be a mixture of an elastomer having an acidic functional group and an elastomer having no acidic functional group. As for the mixing ratio of the elastomer having an acidic functional group and the elastomer having no acidic functional group, when the total of both is 100 mass%, the elastomer having the acidic functional group has high toughness and physical stability of the resin composition. Is preferably 10% by mass or more, more preferably 20% by mass, still more preferably 30% by mass, and most preferably 40% by mass, from the viewpoint of maintaining good. There is no particular upper limit, and substantially all of the elastomer may be an elastomer having an acidic functional group. However, from the viewpoint of not causing a problem in fluidity, 80% by mass or less is desirable.

  In the resin composition, the amount of the elastomer based on 100 parts by mass of the polyamide is preferably in the range of 1 to 50 parts by mass. The upper limit is more preferably 40 parts by mass, more preferably 35 parts by mass, still 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 that the above-mentioned upper limit or less be used. The lower limit is more preferably 2 parts by mass, still more preferably 3 parts by mass, still more preferably 4 parts by mass, and most preferably 5 parts by mass. In order to increase the toughness and stability of physical properties of the resin composition, it is preferably at least the lower limit described above.

  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 as a number average particle diameter. It is as follows. Although there is no particular lower limit, it is, for example, 0.1 μm. From the viewpoints of high toughness and stability of physical properties, the content is preferably within the above range.

  The elastomer preferably has a high uniformity of the dispersed particle diameter. From this viewpoint, the volume ratio of the dispersed particles having a particle diameter of 1 μm or more to the whole dispersed particles of the elastomer is preferably 30% by volume or less. The upper limit is more preferably 25% by volume, still more preferably 20% by volume, even more preferably 15% by volume, and most preferably 10% by volume. In the dispersion particle size distribution on a volume basis, the volume ratio of the dispersed particles having a particle size of 1 μm or more is suddenly increased when there are coarse particles even if the number is very small. When the volume ratio is within the above range, the uniformity of the dispersed particle diameter is preferably high. The volume ratio may be, for example, 2% by volume or more, or 5% by volume or more from the viewpoint of ease of production of the resin composition.

  As a technique for increasing the uniformity of the dispersed particle diameter of the elastomer, a resin composition is manufactured by extruding and kneading the components of the resin composition, and a high shear strain is applied to the components by increasing the screw rotation speed during extrusion kneading. A method of finely dispersing the elastomer by giving, for example, a method of providing a screw component with a narrow clearance such as a seal ring that uniformly exists to give an extension flow strain to the blended component, passing a special narrow slit to the molten polymer, There is a method of giving an extensional flow strain at the slit portion, and any of these methods may be used. However, in the method of applying a high shear, since the polymer temperature rises significantly during processing, a method using the extensional flow strain is used. Is more preferred.

  As a method of observing the dispersion form, a method of cutting the resin composition in the form of a molded product, a pellet, or the like as an ultrathin section, dyeing the polyamide phase with phosphotungstic acid or the like, and observing the same with a transmission electron microscope, After uniformly exposing the surface of the resin composition in the form of a molded article, pellet, or the like, a method of immersing the resin composition in a solvent that selectively dissolves only the elastomer, extracting the elastomer, and observing the same with a scanning electron microscope is known. No. The obtained image is binarized by an image analyzer, the diameter of the dispersed particles of the dispersed phase (at least 500 randomly selected) is calculated as a circle-equivalent diameter, and the particle diameter of each is counted. And the volume ratio of particles having a predetermined particle diameter (for example, the above-mentioned particle diameter of 1 μm or more) can be calculated.

<< cellulose >>
Next, the cellulose that can be used in the present embodiment will be described in detail.
The amount of cellulose that can be used in the present embodiment is preferably in the range of 0.1 to 30% by mass, when the entire resin composition is 100% by mass. A more preferred upper limit is 25% by mass, still more preferably 20% by mass, and most preferably 15% by mass. A more preferred lower limit is 0.5% by mass, still more preferably 1% by mass, and most preferably 3% by mass. In order to suppress the coefficient of thermal expansion and maintain the stability of physical properties, it is preferable to set the above range.

  The cellulose in the present embodiment is a cellulose nanofiber having a diameter of 50 to 1000 nm and an L / D of 30 or more, a cellulose nanocrystal having a diameter of 100 nm or less and an L / D of less than 30, a cellulose microfiber having a diameter of more than 1 μm to 50 μm, or these. Is desirable.

  Cellulose that can be used in this embodiment includes natural cellulose and regenerated cellulose. Examples of natural cellulose include wood pulp obtained from wood species (hardwood or conifer), non-wood pulp obtained from non-wood species (bamboo, hemp fiber, bagasse, kenaf, linter, etc.), and purified pulp thereof (refined linter) Etc.) can be used. As the non-wood pulp, cotton-derived pulp including cotton linter pulp, hemp-derived pulp, bagasse-derived pulp, kenaf-derived pulp, bamboo-derived pulp, straw-derived pulp, and the like can be used. Cotton-derived pulp, hemp-derived pulp, bagasse-derived pulp, kenaf-derived pulp, bamboo-derived pulp, and straw-derived pulp are respectively cotton lint, cotton linter, hemp-based abaca (for example, from Ecuador or the Philippines), Zaisal And refined cellulose obtained from a raw material such as bagasse, kenaf, bamboo, straw, and the like through a purification process such as delignification by digestion, a bleaching process, and the like as a raw material.

  The cellulose nanocrystal (hereinafter, sometimes referred to as CNC) in the present embodiment is obtained by cutting the above-mentioned pulp as a raw material, dissolving an amorphous portion of cellulose in an acid such as hydrochloric acid, sulfuric acid or the like. It is the remaining crystalline cellulose. 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 still 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 still more preferably 5 or more.

  FIG. 1 is a microscope image showing an example of cellulose nanowhiskers (needle-shaped particulate cellulose), and FIG. 1 (B) is a partially enlarged view of FIG. 1 (A). It can be seen that any cellulose has a needle-like crystal particle structure, a diameter of 100 nm or less, and an L / D of less than 30.

  Cellulose nanofiber (hereinafter, sometimes referred to as CNF) refers to a pulp treated with hot water at 100 ° C. or higher to hydrolyze the hemicellulose portion to make it weaker, and then to use a high-pressure homogenizer, a microfluidizer. Refers to cellulose fibrillated by a pulverization method such as a dither, ball mill, and disk mill. The diameter of CNF is 50-1000 nm. The diameter of CNF is more preferably 5 nm or more, further preferably 10 nm or more, more preferably 40 nm or less, and further preferably 20 nm or less. Further, the L / D of CNF is 30 or more, preferably 50 or more, more preferably 80 or more, further preferably 100 or more, preferably 5000 or less, more preferably 4000 or less, and still more preferably 3000 or less. is there.

  FIG. 2 is a microscope image showing an example of a cellulose nanofiber. All celluloses have a fibrous structure, a diameter of 50 to 1000 nm, and an L / D of 30 or more.

  In addition, cellulose microfiber (hereinafter, sometimes referred to as CMF) refers to a relatively large-sized fibrous cellulose obtained by reducing the defibration step in the process of manufacturing CNF. The diameter of the CMF is greater than 1 μm to 50 μm. The diameter of CMF is preferably at least 2 μm, more preferably at least 5 μm, even more preferably at least 10 μm, preferably at most 45 μm, more preferably at most 40 μm, even more preferably at most 35 μm. The L / D of CMF is preferably at least 30, more preferably at least 50, even more preferably at least 70, preferably at most 2,000, more preferably at most 1,000, even more preferably at most 500. CMF is usually obtained with about half the energy of producing CNF.

  FIG. 3 is a micrograph of a cellulose microfiber. It can be seen that any cellulose has a diameter of more than 1 μm to 50 μm and an L / D of 30 or more.

  Preferred aspects of the cellulose in the present embodiment include, from the viewpoint of securing physical stability, single use of CNF, single use of CMF, dual use of CNF and CNC, dual use of CNF and CMF, and CMF. And CNC in combination, and CMF, CNF and CNC in combination. More preferred embodiments include single use of CMF, dual use of CNF and CNC, dual use of CNF and CMF, dual use of CMF and CNC, triple use of CMF, CNF and CNC Use.

  When these two kinds of CNF and CMF are used in combination, the preferable ratio is 50 to 99% by mass of CMF when the total amount of cellulose is 100% by mass. The upper limit of the ratio is more preferably 97% by mass, further preferably 95% by mass, further preferably 93% by mass, and most preferably 90% by mass. The lower limit of the ratio is more preferably 55% by mass, still more preferably 60% by mass, and most preferably 70% by mass.

  Further, when two kinds of CNF and CNC are used in combination, and when two kinds of CMF and CNC are used in combination, when the total amount of cellulose is 100% by mass, the preferred ratio of CNC is 50 to 99% by mass. is there. The upper limit of the ratio is more preferably 97% by mass, further preferably 95% by mass, further preferably 93% by mass, and most preferably 90% by mass. The lower limit of the ratio is more preferably 55% by mass, still more preferably 60% by mass, and most preferably 70% by mass.

  When three kinds of CMF, CNF, and CNC are used in combination, the preferable ratio of CNC is 50 to 99% by mass, when the total amount of cellulose is 100% by mass. The upper limit of the ratio is more preferably 97% by mass, further preferably 95% by mass, further preferably 93% by mass, and most preferably 90% by mass. The lower limit of the ratio is more preferably 55% by mass, still more preferably 60% by mass, and most preferably 65% by mass. Further, assuming that the total amount of cellulose other than CNC is 100% by mass, a preferable ratio of CMF is 50 to 99% by mass. The upper limit of the ratio is more preferably 97% by mass, further preferably 95% by mass, further preferably 93% by mass, and most preferably 90% by mass. The lower limit of the ratio is more preferably 55% by mass, still more preferably 60% by mass, and most preferably 70% by mass.

  Further, the amount of CMF based on 100% by mass of the resin composition is preferably 0.1 to 20% by mass. When the amount of CMF is within the above range, properties such as tensile elongation and vibration fatigue properties can be improved. The lower limit of the above amount is more preferably 1% by mass, further preferably 2% by mass, still more preferably 3% by mass, and most preferably 5% by mass. Further, the upper limit is more preferably 18% by mass, further preferably 16% by mass, further preferably 14% by mass, and most preferably 12% by mass.

  In the present disclosure, the length, diameter, and L / D ratio of each of CNC and CNF are determined by using an aqueous dispersion of each of CNC and CNF with a high-shear homogenizer (for example, Nippon Seiki Co., Ltd .; Using a homogenizer ED-7 "), treatment conditions: an aqueous dispersion dispersed at a rotation speed of 15,000 rpm for 5 minutes was diluted with pure water to 0.1 to 0.5% by mass, and cast on mica. The air-dried sample is used as a measurement sample, and measured by a high-resolution scanning microscope (SEM) or an atomic force microscope (AFM). Specifically, the length (L) and diameter (D) of 100 randomly selected celluloses were measured in an observation field of view in which the magnification was adjusted so that at least 100 celluloses were observed, Calculate the ratio (L / D). Those with a ratio (L / D) of less than 30 are classified as CNC, and those with a ratio of 30 or more are classified as CNF. For each of the CNC and CNF, the number average of the length (L), the number average of the diameter (D), and the number average of the ratio (L / D) are calculated to obtain the CNC and CNF of the present disclosure. Each length, diameter, and L / D ratio are used. In addition, the length and diameter of the cellulose of the present disclosure is the number average value of the 100 celluloses.

  Since CMF has a different size scale from CNC and CNF, and the electron microscope is not suitable for measuring the length, diameter, L / D ratio, etc. of CMF, the size of CMF is observed by another method. Sufficient vibration is applied to the low-concentration aqueous dispersion prepared so that the CMF becomes about 0.1% by mass with an ultrasonic cleaner, or a disperser (for example, Despa Mill manufactured by Asada Iron Works Co., Ltd.) After performing dispersion treatment for 20 minutes to loosen the entanglement between CMFs, the aqueous dispersion is observed as it is with an optical microscope. The measurement and calculation method at this time is the same as that of CNF and CNC.

  Alternatively, the length, diameter, and L / D ratio of each of CMF, CNC and CNF in the resin composition are determined by dissolving the polymer component in the composition in an organic or inorganic solvent capable of dissolving the polymer component of the composition. After separating cellulose and washing thoroughly with the solvent, an aqueous dispersion in which the solvent was replaced with pure water was prepared, and the cellulose concentration was diluted with pure water to 0.1 to 0.5% by mass. The measurement is performed according to the method described above.

The average diameter of the CNC measured by volume average particle diameter is preferably 10 nm or more, more preferably 15 nm or more, still more preferably 20 nm or more, preferably 1000 nm or less, more preferably 500 nm or less, and still more preferably 300 nm or less.
The average diameter of the CNF measured by volume average particle diameter is preferably at least 20 nm, more preferably at least 40 nm, further preferably at least 50 nm, preferably at most 1,000 nm, more preferably at most 700 nm, further preferably at most 500 nm.

The volume average particle diameter is a value obtained as a spherical equivalent diameter (volume average particle diameter) of the particles when the integrated volume becomes 50% by a laser diffraction / scattering particle size distribution analyzer. Specifically, the sample is set to 40% by mass in a planetary mixer (for example, 5DM-03-R manufactured by Shinagawa Kogyo Co., Ltd., hook type stirring blade) at 126 rpm at room temperature under normal pressure. The mixture was kneaded for 0.5 min, then made into a pure water suspension at a concentration of 0.5% by mass, and a high-shear homogenizer (for example, Nippon Seiki Co., Ltd., trade name “Excel Auto Homogenizer ED-7” processing conditions) was used. The dispersion was performed at 15,000 rpm for 5 minutes, and a centrifugal separator (for example, trade name “6800 type centrifuge”, rotor type RA-400 type, manufactured by Kubota Shoji Co., Ltd.) was used. Processing conditions: centrifugal force: 39200 m ² / The supernatant obtained by centrifugation at s for 10 minutes is collected, and the supernatant is further centrifuged at 116000 m ² / s for 45 minutes, and the supernatant after centrifugation is collected. Using this supernatant, a laser diffraction / scattering particle size distribution analyzer (for example, trade name "LA-910" or trade name "LA-950" manufactured by Horiba Seisakusho Co., Ltd.), ultrasonic treatment 1 minute, refractive index 1. The 50% integrated particle diameter in the volume frequency particle size distribution obtained in 20) (that is, the spherical equivalent diameter of the particle when the integrated volume becomes 50% with respect to the volume of the entire particle) is defined as the volume average particle diameter. .

  In the present disclosure, the degree of polymerization of cellulose is an average degree of polymerization measured according to the reduced specific viscosity method using a copper ethylenediamine solution described in the confirmation test (3) of the “Fifteenth Revised Japanese Pharmacopoeia Commentary (issued by Hirokawa Shoten)”. It is.

  Examples of a method for controlling the degree of polymerization of cellulose (that is, the average degree of polymerization) include a hydrolysis treatment. By the hydrolysis treatment, the depolymerization of the amorphous cellulose inside the cellulose fiber proceeds, and the average degree of polymerization decreases. At the same time, the hydrolysis treatment removes impurities such as hemicellulose and lignin in addition to the above-mentioned amorphous cellulose, so that the inside of the fiber becomes porous. Thereby, in a step of applying a mechanical shearing force to the cellulose, such as in a kneading step described later, the cellulose is easily subjected to a mechanical treatment, and the cellulose is easily miniaturized.

  The hydrolysis method is not particularly limited, and examples thereof include acid hydrolysis, alkali hydrolysis, hydrothermal decomposition, steam explosion, and microwave decomposition. These methods may be used alone or in combination of two or more. In the method of acid hydrolysis, for example, α-cellulose obtained as a pulp from a fibrous plant is used as a cellulose raw material, and in a state where this is dispersed in an aqueous medium, an appropriate amount of protonic acid, carboxylic acid, Lewis acid, heteropoly acid, etc. In addition, the average degree of polymerization can be easily controlled by heating while stirring. The reaction conditions such as temperature, pressure, and time vary depending on the type of cellulose, the concentration of cellulose, the type of acid, the concentration of acid, and the like, but are appropriately adjusted so as to achieve a desired average degree of polymerization. For example, there is a condition that the cellulose is treated at 100 ° C. or more and under pressure for 10 minutes or more using a 2% by mass or less aqueous mineral acid solution. Under these conditions, a catalyst component such as an acid penetrates into the cellulose fiber and promotes hydrolysis, so that the amount of the catalyst component to be used can be reduced, and subsequent purification becomes easy. In addition, the dispersion of the cellulose raw material at the time of hydrolysis may contain a small amount of an organic solvent in addition to water as long as the effects of the present invention are not impaired.

<< Hydrophobicization of cellulose >>
The cellulose in the present embodiment may be a cellulose hydrophobized by a hydrophobizing agent. Hydrophobicization weakens the hydrogen bonds between celluloses, contributes to fine dispersion, improves heat resistance as cellulose, and suppresses deterioration due to kneading with a resin. This has the effect of making it less likely to be the starting point of a defect.

  As the hydrophobizing agent, a compound that reacts with a 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 preferable.

  As the esterifying agent, an acid chloride, an acid anhydride and a vinyl carboxylate are preferred. In the reaction of the acid chloride, an alkaline compound may be added for the purpose of neutralizing an acidic substance which is a by-product while acting as a catalyst. Specific examples of the alkaline compound include, but are not limited to, tertiary amine compounds such as triethylamine and trimethylamine; and nitrogen-containing aromatic compounds such as pyridine and dimethylaminopyridine.

  Examples of the acid anhydride include: aliphatic acid anhydrides such as acetic anhydride, propionic anhydride, and butyric anhydride; and dibasic acid anhydrides such as maleic anhydride, succinic anhydride, and phthalic anhydride. In the reaction of the acid anhydride, an acidic compound such as sulfuric acid, hydrochloric acid or phosphoric acid, or an alkaline compound such as triethylamine or pyridine may be added as a catalyst.

As the carboxylic acid vinyl ester, the following formula (1):
R-COO-CH = CH ₂ Formula (1)
ＲIn the formula, R is any one of an alkyl group having 1 to 16 carbon atoms, an alkylene group having 1 to 16 carbon atoms, a cycloalkyl group having 3 to 16 carbon atoms, and an aryl group having 6 to 16 carbon atoms. Vinyl carboxylate represented by｝ is preferred. Vinyl carboxylate includes vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl cyclohexanecarboxylate, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, pivalin More preferably, it is at least one selected from the group consisting of vinyl acrylate, vinyl octylate divinyl adipate, vinyl methacrylate, vinyl crotonate, vinyl pivalate, vinyl octylate, vinyl benzoate, and vinyl cinnamate. . In the esterification reaction with a carboxylic acid vinyl ester, if a strongly basic or weakly basic inorganic salt or organic compound is added as a catalyst, the reaction may proceed efficiently. Examples of such catalysts include potassium carbonate, sodium carbonate, sodium hydrogen carbonate and amine-based organic compounds.

  Among these esterification reactants, in particular, acetic anhydride, propionic anhydride, butyric anhydride, vinyl acetate, vinyl propionate, and at least one selected from the group consisting of vinyl butyrate, among which acetic anhydride and vinyl acetate have a reaction efficiency of It is preferable from the viewpoint of.

  The method of reducing the fiber diameter by reducing the size of the natural cellulose raw material is not particularly limited, but it is preferable to increase the efficiency of the defibration treatment conditions (method for giving a shear field, size of the shear field, etc.). In particular, by impregnating a fibrillation solution containing an aprotic solvent with a cellulose raw material having a cellulose purity of 85% by mass or more, swelling of the cellulose occurs in a short time, and only a small amount of stirring and shearing energy are applied. Are becoming finer. Then, by adding a cellulose modifying agent immediately after defibration, hydrophobized cellulose can be obtained. This method is preferred from the viewpoints of production efficiency and purification efficiency (that is, high cellulose purification of the hydrophobized cellulose) and physical properties of the resin composite.

  The aprotic solvent includes, for example, alkyl sulfoxides, alkyl amides, pyrrolidones and the like. These solvents can be used alone or in combination of two or more.

  Examples of the alkylsulfoxides include di-C1-4 alkylsulfoxides such as dimethylsulfoxide (DMSO), methylethylsulfoxide, and diethylsulfoxide.

  Examples of the alkylamides include N, N-diC1-4alkylformamides such as N, N-dimethylformamide (DMF) and N, N-diethylformamide; N, N-dimethylacetamide (DMAc), N, N -N, N-diC1-4alkylacetamide such as -diethylacetamide.

  Examples of the pyrrolidones include pyrrolidone such as 2-pyrrolidone and 3-pyrrolidone; and N-C1-4 alkylpyrrolidone such as N-methyl-2-pyrrolidone (NMP).

  These aprotic solvents can be used alone or in combination of two or more. Among these aprotic solvents (the number in parentheses is the number of donors), DMSO (29.8), DMF (26.6), DMAc (27.8), NMP (27.3), etc. If is used, hydrophobized cellulose having a high thermal decomposition initiation temperature can be produced more efficiently. The mechanism of this action is not necessarily clear, but is presumed to be due to the homogeneous micro-swelling of the fiber material in the aprotic solvent.

  When the cellulose material swells in the aprotic solvent, the aprotic solvent quickly penetrates and swells the fibrils constituting the material, whereby the microfibrils enter a finely fibrillated state. After creating this state, it is presumed that by performing chemical modification, the hydrophobic treatment progresses uniformly throughout the fine fibers, and as a result, high heat resistance is obtained. Furthermore, the microfibrillated chemically modified fine fibers maintain high crystallinity, and exhibit high mechanical properties and excellent dimensional stability (particularly, a significant decrease in linear thermal expansion coefficient) when combined with a resin. Can be acquired.

  The finely divided (defibrated) and hydrophobized cellulose is subjected to a collision shearing device such as a planetary ball mill and a bead mill, a rotary shearing field which induces the fibrillation of cellulose such as a disc refiner and a grinder, or The kneading, stirring, and dispersing functions, such as various kneaders and planetary mixers, can be obtained by using an apparatus capable of performing the functions with high efficiency.

  In the reflection type infrared absorption spectrum of the hydrophobized cellulose, the peak position of the absorption band changes depending on the type of the hydrophobizing modifying group. From the change in the peak position, it can be determined what absorption band the peak is based on, and the modifying group can be identified. The modification ratio can be calculated from the peak intensity ratio between the peak derived from the modifying group and the peak derived from the cellulose skeleton.

For example, if the modifying group is an ester group, the peak of the C = O absorption band based on the ester group appears at 1730 cm ^-1 , the peak of the C-H absorption band based on the cellulose backbone is 1370 cm ^-1 , The peak of the absorption band of C—O based on the backbone appears at 1030 cm ⁻¹ .

  When the hydrophobic modification group of the hydrophobized cellulose is an ester group, the peak intensity of the absorption band based on the chemical modification group with respect to the peak intensity (height) of the absorption band of the cellulose backbone chain CH in an IR spectrum measured by a reflection type. Modification defined by the ratio (peak height of absorption band of CＣO based on ester group) (peak height of absorption band based on chemical modifying group / peak height of absorption band of cellulose backbone chain CH). The conversion ratio (IR index 1370) is preferably 0.8 or more and 1.8 or less. When the IR index 1370 is 0.8 or more, a resin composite containing hydrophobized cellulose having a high thermal decomposition initiation temperature can be obtained. On the other hand, when the ratio is 1.8 or less, an unmodified cellulose skeleton remains in the hydrophobized cellulose, so that the hydrophobization having both high tensile strength and dimensional stability derived from cellulose and high thermal decomposition initiation temperature derived from chemical modification is achieved. A resin composite containing cellulose can be obtained. The IR index 1370 is more preferably 0.90 or more, still more preferably 0.95 or more, preferably 1.7 or less, more preferably 1.6 or less, and even more preferably 1.5 or less.

  The ratio of the peak intensity (height) of the absorption band based on the chemical modifying group (the peak height of the C = O absorption band based on the ester group) to the peak intensity (height) of the absorption band of the cellulose backbone chain CH The modification rate (IR index 1030) defined by the peak height of the absorption band based on the group / the peak height of the absorption band of the cellulose backbone chain C—O is 0.13 or more and 0.48 or less. preferable. When the IR index 1030 is 0.13 or more, a resin composite containing hydrophobized cellulose having a high thermal decomposition initiation temperature can be obtained. On the other hand, when the ratio is 0.48 or less, the unmodified cellulose skeleton remains in the hydrophobized cellulose, so that the hydrophobization having both high tensile strength and dimensional stability derived from cellulose and high thermal decomposition initiation temperature derived from chemical modification is achieved. A resin composite containing cellulose can be obtained. The IR index 1030 is more preferably at least 0.15, even more preferably at least 0.17, preferably at most 0.45, more preferably at most 0.4, even more preferably at most 0.35.

炭素 Carbon filler for conductivity≪
In a preferred embodiment, the resin composition further includes a conductive carbon-based filler. Thereby, a conductive resin composition can be obtained. Preferred conductive carbon fillers include carbon black, carbon fiber, graphite, graphene, carbon nanotubes and the like. The shape of the conductive carbon-based filler may be any of granular, flake, and fibrous fillers. Specific examples of preferred conductive carbon fillers include conductive carbon black, carbon nanotubes (CNT), carbon fibers, and graphite, among which conductive carbon black and CNT are most preferred.

The absorption amount of dibutyl phthalate (DBP) of the conductive carbon black is preferably 250 ml / 100 g or more, more preferably 300 ml / 100 g or more, and still more preferably 350 ml / 100 g or more. The DBP absorption here is a value measured by a method specified in ASTM D2414. Further, the conductive carbon black preferably has a BET surface area of 200 m ² / g or more, and more preferably 400 m ² / g or more. Ketjen Black EC-600JD and the like are examples of the conductive carbon black that can be obtained as a commercially available product.

The conductive carbon black in the present embodiment is added in a small amount unlike general carbon black for coloring (usually, the DBP absorption is less than 250 ml / 100 g and the BET surface area is less than 200 m ² / g). And exhibit good conductivity.

  Carbon nanotubes (CNT) are carbon fibers having a fiber diameter of 100 nm or less and having a hollow structure. CNTs include both single-walled carbon nanotubes whose tube walls are formed of single-walled carbon and multi-walled nanotubes formed of multi-walled carbon.

  The conductive carbon-based filler may be one which has been treated with various known coupling agents and / or sizing agents to improve the adhesion to the resin and / or the handleability.

  The preferable amount of the conductive carbon-based filler is 0.1 to 10% by mass when the entire resin composition is 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, still more preferably 0.5% by mass, and most preferably 0.8% by mass. In order to maintain a stable balance between the conductivity and the fluidity of the resin composition, it is desirable that the content is within the above range.

≪Aggregation inhibitor 抑制
Cellulose has the property of being agglomerated in the drying step and difficult to redisperse. Therefore, it is preferable to use an aggregation inhibitor to enhance the redispersibility of cellulose when melt-kneaded with the resin. By increasing the redispersibility, the mechanical properties and stability of the obtained resin composition can be improved. The coagulation inhibitor is preferably added to the aqueous cellulose dispersion, and then dried while applying shear to obtain a cellulose powder.

  The preferred amount of the aggregation inhibitor is 2 to 100 parts by mass based on 100 parts by mass of cellulose. The lower limit is more preferably 4 parts by mass, still more preferably 5 parts by mass, and most preferably 6 parts by mass. The upper limit is more preferably 80 parts by mass, still more preferably 60 parts by mass, and most preferably 40 parts by mass. In order to increase the dispersibility of the cellulose in the resin and to improve the stability of the physical properties, it is desirable that the content is within the above range.

  The aggregation inhibitor can be at least one selected from the group consisting of a surfactant, an organic compound having a boiling point of 100 ° C. or higher, and a resin having a chemical structure capable of highly dispersing cellulose.

  The surfactant only needs to have a chemical structure in which a site having a hydrophilic substituent and a site having a hydrophobic substituent are covalently bonded, and are used for various purposes such as food and industrial use. Can be used. For example, the following can be used alone or in combination of two or more.

  As the surfactant, any of an anionic surfactant, a nonionic surfactant, an amphoteric surfactant, and a cationic surfactant can be used. In the above, an anionic surfactant and a nonionic surfactant are preferable, and a nonionic surfactant is more preferable.

  Among the above, in terms of affinity with cellulose, a surfactant having a polyoxyethylene chain as a hydrophilic group, a carboxyl group, or a hydroxyl group is preferable, and a polyoxyethylene-based surfactant having a polyoxyethylene chain as a hydrophilic group (Polyoxyethylene derivative) is more preferable, and a nonionic polyoxyethylene derivative is more preferable. The polyoxyethylene chain length of the polyoxyethylene derivative is preferably 3 or more, more preferably 5 or more, still more preferably 10 or more, and particularly preferably 15 or more. The longer the chain length, the higher the affinity for cellulose, but in the balance with coating properties, the upper limit is preferably 60 or less, more preferably 50 or less, still more preferably 40 or less, and particularly preferably 30 or less. Most preferred is 20 or less.

  Among the above-mentioned surfactants, particularly, as the hydrophobic group, alkyl ether type, alkyl phenyl ether type, rosin ester type, bisphenol A type, β-naphthyl type, styrenated phenyl type, and hydrogenated castor oil type have affinity for resin. , So that it can be suitably used. 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, still 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. There is no upper limit, but the upper limit is preferably 30 or less, more preferably 25 or less.

  Among these hydrophobic groups, those having a cyclic structure or those having a bulky and multifunctional structure are preferable. Those having a cyclic structure are preferably alkylphenyl ether type, rosin ester type, bisphenol A type, β-naphthyl type and styrenated phenyl type, and those having a polyfunctional structure are preferably hardened castor oil type. Among them, the rosin ester type and the hardened castor oil type are particularly preferable.

  Further, an organic compound having a boiling point of 100 ° C. or higher may be effective as a non-surfactant dispersion medium. Examples of such an organic compound include polyethylene glycol, polypropylene glycol, an organic compound having a glycerin structure, and the like. Although it depends on the type of the resin, for example, when the resin is a polyolefin, a high-boiling organic solvent such as liquid paraffin or decalin is effective. When the resin is a polar resin such as nylon and polyacetate, it may be effective to use a solvent similar to an aprotic solvent that can be used in producing cellulose, for example, dimethyl sulfoxide.

≪Coefficient of variation≫
In the resin composition of the present embodiment, the coefficient of variation CV of the tensile strength at break is preferably 10% or less from the viewpoint of eliminating the strength defect of the obtained molded article. The coefficient of variation referred to here is expressed as a percentage obtained by dividing the standard deviation (σ) by the arithmetic mean (μ) and multiplying by 100, and is a unitless number representing relative variation.
CV = (σ / μ) × 100
Here, μ and σ are given by the following equations.

Here, xi is a single piece of data of the tensile breaking strength among the n pieces of data x1, x2, x3... Xn.

  The number of samples (n) when calculating the coefficient of variation CV of the tensile strength at break is preferably at least 10 or more in order to easily find the defect. More preferably, it is 15 or more.

  A more preferred upper limit of the variation coefficient is 9%, further preferably 8%, more preferably 7%, still more preferably 6%, and most preferably 5%. The lower limit is preferably zero, but is preferably 0.1% from the viewpoint of manufacturability.

  It is considered that the partial strength defect of the conventional resin molded product is caused by uneven dispersion of fillers and the like, formation of voids (voids), and the like. As an index for evaluating the easiness of formation of the strength defect, there is a method in which a tensile test is performed on a plurality of test pieces and the presence / absence and the number of variations in the breaking strength are confirmed.

  For example, due to the presence of non-uniformly dispersed portions of fillers, voids, etc. in a molded body of a structural component such as an automobile body, a door panel, a bumper, etc., when a large stress is momentarily applied to the molded body, Although the stress is small as described above, when the stress is repeatedly applied, the stress is concentrated and the molded body is broken. This results in reduced product reliability.

  Until now, it has been difficult to foresee the structural defect occurring in the actual product at the test stage. For example, a method of confirming a defective portion in the product with a microscope or the like has been used. However, observation with a microscope is extremely microscopic observation, and it was not possible to comprehensively evaluate the entire test piece and the entire product.

  The present inventors have found out that there is a correlation between the coefficient of variation in tensile rupture strength and the ratio of structural defects of a product during various studies.

  To describe in more detail, for example, if the material has a homogeneous internal structure and does not have voids and the like, even when a tensile break test of a plurality of samples is performed, the stress at the time of breakage is between the plurality of samples. The values are almost the same, and the coefficient of variation is very small. However, a material having a non-uniform portion, a void, or the like inside has a large difference between the stress at break in one sample and the stress in another sample. Such a degree of the number of samples exhibiting stress different from the stress of other samples can be clarified by using a scale called a coefficient of variation.

  For example, in the case of a material having no yield strength, for example, a sample having an internal defect leads to fracture at a lower strength than other samples. Also, in the case of a material having a yield strength, after the yield, it often breaks on the way to necking, and the sample having a defect inside has a higher strength than the other samples. The tendency to reach. Although there is a difference in the behavior in this way, the possibility of occurrence of a strength defect in an actual product can be expected by using a scale of a coefficient of variation of tensile strength at break.

  It is considered that the dispersion state and the dispersion position of the cellulose in the composition greatly influence the variation coefficient of the tensile strength at break. In the case of a polyamide / elastomer alloy, the elastomer phase and the interface layer between the elastomer and the polyamide are important parts for stabilizing the physical properties. For example, when cellulose is localized at the interface between the dispersed phase and the continuous phase or in the dispersed phase, the localized portion becomes a stress concentration point, and the stability of physical properties is greatly reduced. That is, by stably dispersing cellulose in the polyamide phase, the stability of physical properties is increased.

  There are various techniques for stably dispersing cellulose in the polyamide phase. For example, a method of optimizing the composition ratio of polyamide and elastomer, a method of optimizing the amount of acidic functional groups of the elastomer, a method of optimizing the terminal group concentration of polyamide, and optimizing the order of addition when kneading cellulose. , A method of weakening the affinity between the elastomer and the cellulose or increasing the affinity with the polyamide by adding an optimal surfactant or the like, a method of previously melt-mixing the polyamide and the cellulose to form a master batch, an extruder There are various approaches such as a method of optimizing the screw arrangement during processing and a method of optimizing the resin viscosity by controlling the temperature during processing.

  In addition to the above, the stability of physical properties is increased by improving the heat resistance of cellulose and preventing it from becoming a starting point of structural defects due to thermal degradation during kneading with a resin.

  Either of these approaches may be employed to stably disperse the cellulose in the polyamide phase. Setting the coefficient of variation CV of the tensile strength at break to 10% or less can contribute to the elimination of the strength defect of the obtained molded article, and has the effect of greatly improving the strength of the molded article.

  In the resin composition of the present embodiment, the tensile yield strength tends to be dramatically improved as compared with the thermoplastic resin alone. The ratio of the tensile yield strength of the resin composition, when the tensile yield strength of the thermoplastic resin alone is set to 1.0, is preferably 1.1 times or more, more preferably 1.15 times or more, and even more. It is preferably at least 1.2 times, most preferably at least 1.3 times. The upper limit of the ratio is not particularly limited, but is preferably, for example, 5.0 times, and more preferably 4.0 times, from the viewpoint of ease of production.

  Since the resin composition of this embodiment contains cellulose, it is possible to exhibit low thermal expansion without increasing the specific gravity. Specifically, the thermal expansion coefficient of the resin composition in a temperature range of 20 ° C. to 100 ° C. is preferably 50 ppm / K or less, more preferably 45 ppm / K or less, and even more preferably 40 ppm / K or less. And most preferably 35 ppm / K or less. The lower limit of the thermal expansion coefficient is not particularly limited, but is preferably, for example, 5 ppm / K, and more preferably 10 ppm / K, from the viewpoint of ease of production.

  The resin composition of the present embodiment also has a feature that the dispersion of the linear expansion coefficient in a large molded product is small because cellulose is finely dispersed in the polyamide phase stably. Such a feature is particularly remarkable when the polyamide phase is a continuous phase. Specifically, the characteristic is that the variation of the coefficient of linear expansion measured using the test pieces collected from different portions of the large molded body is extremely low.

  When the dispersion of cellulose in the resin composition is non-uniform and the coefficient of linear expansion differs greatly depending on the site, a problem such as distortion or warpage of the molded body is likely to occur due to temperature change. In addition, this failure is a failure mode that occurs due to a difference in thermal expansion and reversibly occurs when the temperature rises and falls. Therefore, the failure mode may have a potential danger that it cannot be recognized by checking at room temperature.

  The magnitude of the variation in the coefficient of linear expansion can be expressed using the coefficient of variation of the coefficient of linear expansion of the measurement sample obtained from a different part. The coefficient of variation here is the same as that described in the section on the coefficient of variation of tensile strength at break.

  The coefficient of variation of the coefficient of linear expansion in the resin composition of the present embodiment is preferably 15% or less. The upper limit of the coefficient of variation is more preferably 13%, still more preferably 11%, even more preferably 10%, even more preferably 9%, and most preferably 8%. The lower limit is preferably zero, but is preferably 0.1% from the viewpoint of manufacturability.

  The number of samples (n) for calculating the coefficient of variation of the linear expansion coefficient is desirably at least 10 or more in order to reduce the influence of data errors and the like.

  In the resin composition of the present embodiment, as other components, for example, a fine fiber filler component (for example, fibrillated fiber or fine fiber of aramid fiber) composed of a high heat-resistant organic polymer other than cellulose; 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; coloring agents; fragrances; pigments; An additive such as an agent; a leveling agent; a conductive agent; an antistatic agent; an ultraviolet absorber; an ultraviolet dispersant; The content ratio of the optional additive in the resin composition is appropriately selected within a range that does not impair the desired effect of the present invention.

  The resin composition of the present embodiment can be provided in various shapes. Specific examples include resin pellets, sheets, fibers, plates, rods, and the like, and the resin pellets are more preferable in terms of ease of post-processing and transportation. Preferable pellet shapes at this time include a round shape, an elliptical shape, a cylindrical shape, and the like, which differ depending on a cutting method at the time of extrusion. Pellets cut by a cutting method called underwater cut are often round, and pellets cut by a cutting method called hot cut are often round or oval, and cuts called strand cuts The pellets cut by the method often have a columnar shape. In the case of a round pellet, the preferred size is 1 mm or more and 3 mm or less as a pellet diameter. Further, in the case of a cylindrical pellet, a preferred diameter is 1 mm or more and 3 mm or less, and a preferred length is 2 mm or more and 10 mm or less. The above-mentioned diameter and length are desirably not less than the lower limit from the viewpoint of operation stability during extrusion, and desirably not more than the upper limit from the viewpoint of biting into a molding machine in post-processing.

  The resin composition of the present embodiment can be used as various resin molded articles. There is no particular limitation on the method for producing the resin molded body, and any production method may be used, but an injection molding method, an extrusion molding method, a blow molding method, an inflation molding method, a foam molding method, or the like can be used. Of these, the injection molding method is most preferable from the viewpoint of design and cost.

  The method for producing the resin composition of the present embodiment is not particularly limited, but specific examples include the following methods.

  Using a single-screw or twin-screw extruder, melt-kneading a mixture of polyamide, elastomer, and cellulose, extruding into a strand, cooling and solidifying in a water bath to obtain a pellet-shaped molded body, single-screw or twin-screw extrusion Similarly, melt-kneading, extruding into a rod or tube, cooling and extruding to obtain an extruded body, melt-kneading using a single-screw or twin-screw extruder, and extruding a sheet or film from a T-die. And a method for obtaining a molded article of

  The resin composition of the present embodiment has high mechanical properties and low linear expansion properties, and has not only high fluidity that can be used for large parts, but also substantially does not substantially include partial strength defects. Therefore, it can be suitably used for various large parts applications.

  The present invention will be further described based on examples, but the present invention is not limited to these examples.

[Raw materials and evaluation method]
Hereinafter, the used raw materials and the evaluation method will be described.

≪Polyamide≫
Terminal carboxy group-rich polyamide 6 (hereinafter simply referred to as PA6-1)
UBE nylon 1013B (Ube Industries, Ltd.)
Carboxyl end group ratio is ([COOH] / [all end groups]) = 0.6
Viscosity number (VN) of polyamide measured in 96% strength by weight sulfuric acid = 95
Terminal amino group-rich polyamide 6 (hereinafter simply referred to as PA6-2)
UBE nylon 1013A (Ube Industries, Ltd.)
Carboxyl end group ratio is ([COOH] / [all end groups]) = 0.3
Viscosity number (VN) of polyamide measured in 96% strength by weight sulfuric acid = 95

≪Elastomer≫
Elastomer having acidic functional group Tuftec M1943 (Asahi Kasei Corporation) (hereinafter simply referred to as MSEBS)
Maleic anhydride-modified styrene-ethylenebutylene-styrene block copolymer Bound styrene content = 20% by mass
Acid value: 10 mg CH ₃ ONa / g
MFR (230 ° C., 2.16 kgf) = 8 g / 10 minutes Fusabond MN-493D (Dow Dupont) (hereinafter simply referred to as MEOR)
Maleic anhydride-modified ethylene-octene copolymer MFR (190 ° C., 2.16 kgf) = 1.2 g / 10 min Octene content = 28% by mass
Melting point = 55 ° C (DSC method: heating rate 10 ° C / min)
Maleic anhydride addition rate = 1.0% by mass
Elastomer having no acidic functional group Tuftec H1052 (Asahi Kasei Corporation) (hereinafter simply referred to as SEBS)
Styrene-ethylene butylene-styrene block copolymer Bound styrene content = 20% by mass
MFR (230 ° C., 2.16 kgf) = 13 g / 10 min Engage 8180 (The Dow Chemical Company) (hereinafter simply referred to as EOR)
Ethylene-octene copolymer MFR (190 ° C., 2.16 kgf) = 0.5 g / 10 min Octene content = 28 mass%
Melting point = 49 ° C (DSC method: heating rate 10 ° C / min)

≪Cellulose≫
[Preparation Example 1] Cellulose nanocrystal (hereinafter referred to as CNC)
Commercial DP pulp (average degree of polymerization: 1600) was cut and hydrolyzed in a 10% by mass aqueous hydrochloric acid solution at 105 ° C. for 30 minutes. The obtained acid-insoluble residue was filtered, washed and pH-adjusted to prepare a crystalline cellulose dispersion having a solid content of 14% by mass and a pH of 6.5. This crystalline cellulose dispersion was spray-dried to obtain a dried crystalline cellulose. Next, with the supply amount being 10 kg / hr, the dried product obtained above was supplied to an airflow type pulverizer (STJ-400, manufactured by Seishin Enterprise Co., Ltd.) and pulverized to obtain CNC as fine crystalline cellulose powder.
As a result of evaluating the characteristics of the obtained CNC, the diameter was 30 nm and the L / D was 8.

  After adding 5 parts by mass of polyethylene glycol having a molecular weight of 20,000 (hereinafter, referred to as PEG 20000) to 100 parts by mass of the CNC to the obtained aqueous dispersion of CNC, a revolving / rotating stirrer (V-mini300 manufactured by EME). ) To obtain a CNC powder by vacuum drying at about 40 ° C.

[Preparation Example 2] Cellulose nanofiber (hereinafter referred to as CNF)
After cutting the linter pulp, the purified pulp from which the hemicellulose portion has been removed is heated in a hot water of 120 ° C. or more for 3 hours using an autoclave, and the solid content becomes 1.5% by mass in pure water. After the fibers were highly shortened and fibrillated by beating as described above, the fibers were fibrillated at the same concentration using a high-pressure homogenizer (operating pressure: processing 10 times at 85 MPa) to obtain fibrillated cellulose. Here, in the beating process, a disc refiner is used, and after processing for 4 hours with a beating blade having a high cutting function (hereinafter, referred to as a cutting blade), using a beating blade having a high defibrating function (hereinafter, referred to as a defibrating blade). The beating was performed for another 1.5 hours.
When the characteristics of the obtained CNF were evaluated, the diameter was 90 nm, and the L / D was 30 or more (about 300).

  After adding 5 parts by mass of PEG 20,000 to 100 parts by mass of CNF to the obtained aqueous dispersion of CNF, the mixture was vacuum-dried at about 40 ° C. using a revolution / rotation type stirrer (V-mini300 manufactured by EME). And CNF powder.

[Preparation Example 3] Hydrophobized CNF (hereinafter referred to as hydrophobized CNF)
(Fibrillation process)
The linter pulp raw material was stirred in a dimethyl sulfoxide (DMSO) at 500 rpm for 1 hour at room temperature using a uniaxial stirrer (DKV-1 φ125 mm dissolver manufactured by Imex). Subsequently, the mixture was fed to a bead mill (NVM-1.5, manufactured by Imex Co., Ltd.) using a hose pump, and circulated only with DMSO for 120 minutes to obtain a defibrated slurry.

(Fibrillation / acetylation process)
Then, after adding 11 parts by mass of vinyl acetate and 1.63 parts by mass of sodium hydrogencarbonate to 100 parts by mass of the defibrated slurry into the bead mill, a circulation operation was further performed for 60 minutes to obtain a hydrophobized CNF slurry.

  During the circulation operation, the rotation speed of the bead mill was 2500 rpm and the peripheral speed was 12 m / s. The beads were made of zirconia, φ2.0 mm, and the filling rate was 70% (the slit gap of the bead mill at this time was 0.6 mm). During the circulation operation, the slurry temperature was controlled at 40 ° C. by a chiller in order to absorb the heat generated by friction.

  Pure water was added to the obtained hydrophobized CNF slurry in an amount of 192 parts by mass with respect to 100 parts by mass of the fibrillated slurry, and the mixture was sufficiently stirred, and then concentrated in a dehydrator. The washing operation of dispersing, stirring, and concentrating the obtained wet cake again in the same amount of pure water was repeated a total of five times.

  When the properties of the obtained hydrophobized CNF were evaluated, the diameter was 65 nm, and the L / D was 30 or more (about 450).

  After adding 5 parts by mass of PEG 20000 to 100 parts by mass of the hydrophobized CNF to the obtained aqueous dispersion of hydrophobicized CNF (solid content: 10% by mass), a revolving / rotating stirrer (V- manufactured by EME) By vacuum drying at about 40 ° C. using mini300), a hydrophobized CNF powder was obtained.

[Preparation Example 4] Hydrophobized cellulose fiber (hereinafter referred to as hydrophobized CellF)
(Fibrillation process)
A fibrillated slurry was obtained in the same manner as in Preparation Example 2, except that the treatment with the high-pressure homogenizer was performed twice. The obtained fibrillated slurry was carried out in the same manner as in the fibrillation / acetylation step of Preparation Example 3.
When the properties of the obtained hydrophobized CMF were evaluated, the diameter was 12 μm, and the L / D was 30 or more (about 200).

  After adding 5 parts by mass of PEG 20,000 to 100 parts by mass of hydrophobized CNF to the obtained aqueous dispersion of hydrophobicized CMF (solid content: 10% by mass), a revolving / rotating stirrer (V- manufactured by EME) By vacuum drying at about 40 ° C. using mini300), a hydrophobized CNF powder was obtained.

≪Conductive material, hereinafter referred to as KB≫
Conductive carbon black Ketjen Black EC-600JD (Lion Specialty Chemicals Co., Ltd.)
DBP absorption = 495cm ³ · 100g
BET specific surface area = 1270 m ² / g

<CNF, CNC, length, diameter, L / D of hydrophobized CNF>
Cellulose was made into a pure water suspension at a concentration of 1% by mass, and was treated with a high shear homogenizer (manufactured by Nippon Seiki Co., Ltd., trade name “Excel Auto Homogenizer ED-7”, processing condition: rotation speed 15,000 rpm × 5 minutes). The dispersed water dispersion is diluted with pure water to 0.1 to 0.5% by mass, cast on mica, and air-dried, and is obtained when measured by an atomic force microscope (AFM). The ratio (L / D) in the case where the length (L) and the diameter (D) of the particle image were determined was calculated as an average value of 100 to 150 particles.

<Average diameter of CNF, CNC, hydrophobized CNF>
In a planetary mixer (trade name “5DM-03-R”, manufactured by Shinagawa Kogyo KK, trade name “5DM-03-R”, stirring blade is a hook type), the cellulose component was set to 40% by mass as solid content, at 126 rpm for 30 minutes at room temperature and normal pressure. Kneaded. Next, a pure water suspension having a solid content of 0.5% by mass was prepared, and a high shear homogenizer (manufactured by Nippon Seiki Co., Ltd., trade name "Excel Auto Homogenizer ED-7"), processing conditions: 15,000 rpm × 5 minutes), and centrifuged (Kubota Shoji Co., Ltd., trade name “6800 type centrifuge”, rotor type RA-400), processing conditions: centrifuged at 39200 m ² / s for 10 minutes, and supernatant Was collected, and the supernatant was centrifuged at 116,000 m ² / s for 45 minutes.) Using the supernatant liquid after centrifugation, the volume obtained by a laser diffraction / scattering particle size distribution analyzer (trade name “LA-910”, manufactured by HORIBA, Ltd., ultrasonic treatment for 1 minute, refractive index 1.20). The integrated 50% particle diameter (volume average particle diameter) in the frequency particle size distribution was measured, and this value was defined as the average diameter.

<CMF diameter, L / D>
The CMF slurry was diluted to make a low-concentration aqueous dispersion of about 0.1% by mass, and subjected to a dispersion treatment for 20 minutes with a Despa mill (manufactured by Asada Iron Works Co., Ltd.). Then, the diameter and the L / D (each number average of 200 pieces) were observed and calculated.

<Confirmation of continuous phase>
The obtained pellet was immersed in chloroform, and the presence or absence of a change in shape was confirmed. Since there was no particular change in the examples and comparative examples performed this time, it was determined that the polyamide formed a continuous phase.

<Cellulose present phase>
In order to confirm the location of cellulose, as a first means, the obtained composition was photographed with a transmission electron microscope, and the amount of cellulose present in the polyamide phase and the amount of cellulose present in the elastomer phase were determined. confirmed. At this time, the cellulose in the polyamide phase was confirmed by dyeing the polyamide phase, and the cellulose in the elastomer phase was suitably dyed with a known dye, so that the cellulose could be clearly confirmed.

  When the position of cellulose was clearly determined by the first means, the second means was not performed, and "----" was described in the column of Examples.

  For samples in which the presence state of cellulose could not be clearly determined by electron microscope observation, a solvent elution method was performed as a second means. Specifically, using an ultramicrotome, the obtained composition is sliced at a thickness of 1 μm to obtain a film-like sample, immersed in chloroform, eluted with an elastomer phase, concentrated, and concentrated by ultracentrifugation. After separation and separation of the cellulose, the cellulose was washed with chloroform and ultracentrifuged three times. The finally remaining cellulose was dried to obtain the amount of cellulose present in the elastomer phase. The obtained amount was subtracted from the charged amount, and the ratio divided by the charged cellulose amount was expressed as a percentage, which was defined as a cellulose polyamide phase ratio. At this time, in the case of the sample in which the conductive filler was coexisted, the sample before the addition of the conductive filler was verified.

<Number average particle diameter of elastomer dispersed particles and volume ratio of dispersed particles having a particle diameter of 1 μm or more>
Using electron micrographs when confirming the location of cellulose, the number average value of the diameter (ie, the dispersed particle diameter) and the volume of the dispersed particles having a particle diameter of 1 μm or more were obtained for 500 dispersed particles of the elastomer dispersed phase. The ratio was calculated.

≪density≫
A multipurpose test piece based on ISO294-3 was molded using an injection molding machine. The molding was performed under the conditions based on JIS K6920-2.
A measurement sample was cut out from the obtained test piece, and the density was measured according to ISO 1183.

≪Thermal expansion (linear expansion coefficient) ≫
From the center of the multi-purpose test piece, a 4 mm long, 4 mm wide, and 4 mm long cubic sample is cut out with a precision cut saw, and the measurement temperature range is from -10 to 120 ° C., and in accordance with ISO11359-2, the resin at the time of molding is cut out. The expansion coefficient in the flow direction (MD direction) was measured, and the expansion coefficient between 20 ° C and 100 ° C (hereinafter, referred to as CTE _MD ) was calculated. At this time, prior to the measurement, annealing was performed by allowing the sample to stand at 120 ° C. for 5 hours.

≪anisotropic≫
Except that the measurement direction of the thermal expansion coefficient was changed to the direction perpendicular to the flow direction of the resin at the time of molding, the measurement was performed in the same manner as the measurement of the thermal expansion property (linear expansion coefficient). CTE _TD ) was calculated. Based on the obtained results, it was evaluated as anisotropic by the following equation.
Anisotropy (%) = CTE _MD / CTE _TD × 100

≪Toughness Strain at tensile fracture≫
Using a multipurpose test piece, a tensile test was performed in accordance with ISO527, and five data points of strain at the time of tensile fracture were arithmetically averaged to obtain an index of toughness.

変 動 Coefficient of variation of linear expansion coefficient≫
Using the pellets obtained in the example, the cylinder temperature of an injection molding machine with a maximum clamping pressure of 4000 tons was set at 250 ° C., and a predetermined mold capable of molding a fender having the shape shown in the schematic diagram of FIG. (Cavity volume: about 1400 cm ³ , average thickness: 2 mm, projected area: about 7000 cm ² , number of gates: 5 gates, hot runner: a runner for clarifying the runner position of the molded article in FIG. 4 (The relative position 1 of the (hot runner) is shown.), The mold temperature was set to 60 ° C., and the fender was molded.

  Using the obtained fender, it was cut out from the position of (1) to (10) in FIG. 5 to about 10 mm square, and 10 small flat plate test pieces of about 10 mm in length, about 10 mm in width, and 2 mm in thickness were collected. . (1) to (3) are the vicinity of the molded body gate, (4) to (7) are the flow end portions of the molded body, and (8) to (10) are the central part of the molded body.

  The obtained small flat plate test piece was further cut into a rectangular parallelepiped sample for measurement having a length of 4 mm, a width of 2 mm, and a length of 4 mm using a precision cut saw. The lateral portion of the rectangular parallelepiped sample at this time is in the thickness direction of the fender.

Prior to the measurement, the sample was left standing at 120 ° C. for 5 hours to perform annealing, thereby obtaining a sample for measurement. The obtained sample is measured in a measurement temperature range of −10 ° C. to + 80 ° C. in accordance with ISO11359-2, and an expansion coefficient between 0 ° C. and 60 ° C. is calculated, and a total of 10 measurement results are obtained. Was. The coefficient of variation (CV) was calculated based on the following measurement data based on the ten measurement data.
CV = (σ / μ) × 100
Here, σ represents a standard deviation, and μ represents an arithmetic average of tensile breaking strength.

≪Conductivity≫
In Examples and Comparative Examples to which a conductive material was added, volume resistivity was measured as conductivity.
For the volume resistivity, a multipurpose test piece was molded from the obtained resin composition pellet. The test piece was previously scratched with a cutter knife, immersed in dry ice / methanol at −75 to −70 ° C. for 1 hour, taken out, and immediately cut off to break both ends into a uniform cross-sectional area of 10 × 4 mm. A test piece for measurement having a cross section and a length of 70 mm was prepared. After applying silver paint to the fracture surfaces at both ends and drying, the volume resistance between both fracture surfaces was measured using a digital ultra-high resistance / micro ammeter [R8340A: manufactured by Advantest] at an applied voltage of 250V. And the volume resistivity were calculated. The measurement was performed on five different test pieces, and the average of the results was used as the volume resistivity.

<Extruder design-1>
The cylinder 1 of a twin-screw extruder (TEM SX series extruder manufactured by Toshiba Machine Co., Ltd.) having 13 cylinder blocks and an L / D of 52 is water-cooled, the cylinders 2 to 4 are cooled to 150 ° C., and the cylinders 5 to dies. Was set to 250 ° C. The cylinder 12 was provided with a vent port for suction under reduced pressure, so that volatile components and coexisting air could be removed.

  As for the screw configuration, cylinders 1-2 are used as conveying screws, and three clockwise kneading disks (feed type kneading disks: hereinafter sometimes simply referred to as RKD) are arranged in cylinder 3 to form a premixing zone. The cylinder 4 is used as a conveying screw, and one RKB and two neutral kneading disks (non-conveying type kneading disks: hereinafter may be simply referred to as NKD) from cylinders 5 to 6 followed by one. Was provided as a melt-kneading zone. The cylinders 7 to 9, which are side feed zones, were used as conveying screws, and the cylinder 10 was provided with two RKBs, followed by three NKBs, and subsequently a counterclockwise screw to form a kneading zone. The cylinders 11 to 13 were used as conveying screws and used as devolatilization zones. In addition, a die having two holes having a diameter of 3 mm was attached to the die.

<Extruder design-2>
A side feed port is provided in the cylinder 7 of the extruder design-1 so that the raw material can be supplied from this position and the outside is the same.

<Extruder design-3>
Extruder design-2 was the same except that one counterclockwise screw was changed to two seal rings having a clearance of 0.2 mm among the screws arranged over cylinders 5 and 6.

<Extruder Design-4>
The vent port for vacuum suction provided in the cylinder 12 of the extruder design-1 was moved to the cylinder 7, and the dice passed through a slit-shaped die having a thickness of 0.15 mm from a normal die. Extruder design-1 was followed except that the die was later changed to a die having two 3 mm diameter holes.

[Preparation Example 5]
Using an extruder of extruder design-1, 70 parts by mass of PA6-1 and 30 parts by mass of hydrophobized CNF were quantitatively fed by different loss-in-weight type feeders from the upstream feed port using different loss-in-weight feeders. While performing, the mixture was melt-kneaded at a screw rotation speed of 300 rpm to obtain master batch pellets. This masterbatch pellet is designated as PA6-1 / hydrophobized CNF. This master batch contains a small amount of 20,000 added during the drying of the hydrophobized CNF.

[Preparation Example 6]
Using an extruder of extruder design-1 in which all cylinders and dies were set at a temperature of 150 ° C., 70 parts by mass of MEOR and 30 parts by mass of hydrophobized CNF were supplied from the upstream supply port to different loss-in-weight systems. The feed was quantitatively fed by a feeder, and the mixture was melt-kneaded at a screw rotation speed of 300 rpm while performing suction under reduced pressure to obtain master batch pellets. This masterbatch pellet is called MEOR / hydrophobized CNF. The master batch also contains a small amount of 20,000 added during the drying of the hydrophobized CNF.

[Examples 1 and 2, Comparative Examples 1 and 2]
Using an extruder of Extruder Design-1, the components were mixed at the ratios shown in Table 1, melt-kneaded at a screw rotation speed of 300 rpm, and obtained as pellets. The results are shown in Table 1.
The column of parts by mass in the table indicates the charged formulation, the column of mass% in the middle indicates the composition, and the lower column indicates the physical properties.

  From the results shown in the table, Comparative Examples 1 and 2 in which the polyamide phase did not contain more than 50% by mass of cellulose in spite of almost the same composition, had a high linear expansion coefficient and a large strain at the time of tensile failure. It can be seen that the variation in the coefficient of linear expansion b varies depending on the region. This is considered to be due to the fact that cellulose is mainly present in the elastomer phase, whereby the effect of reducing linear expansion cannot be sufficiently exhibited, and further, the effect of the elastomer to exert impact is suppressed.

[Examples 3 and 4, Comparative Examples 3 and 5]
Using an extruder of Extruder Design-1, mixing was performed at the ratios shown in Table 2, melt-kneading was performed at a screw rotation speed of 300 rpm, and pellets were obtained. The results are shown in Table 2.

  From the results shown in Table 2, it can be seen that the location of the cellulose and the properties of the rubber vary greatly depending on the amount of the elastomer having an acidic functional group in the rubber. Despite not using a masterbatch, the reason for the presence of cellulose in a small amount of the elastomer phase is that the elastomer melts at a much lower temperature than the polyamide and is first kneaded with the cellulose, It is considered that the affinity of the elastomer with cellulose was increased by the acid modification of the elastomer.

[Examples 5 to 12]
Using an extruder of Extruder Design-1, mixing was performed at the ratios shown in Table 3, melt-kneading was performed at a screw rotation speed of 300 rpm, and pellets were obtained. The results are shown in Table 3.
In addition, Example 3 was reprinted to facilitate understanding.

[Comparative Examples 6, 7]
Using an extruder of Extruder Design-2, mixing was performed at the ratios shown in Table 4, and the resulting mixture was melt-kneaded at a screw rotation speed of 300 rpm to obtain pellets. Table 4 shows the results.

  In addition, Example 12 was reprinted in order to help understand the difference depending on the type of the filler. In Example 12, although the extruder design was different, the filler amount was 10% by mass, which was the same amount.

  From the results shown in Table 4, it can be seen that when a general inorganic filler is used in place of cellulose, the density is increased, the weight reduction effect is reduced, and problems such as anisotropy appear. Due to the large anisotropy, the formed fender molded body had a large warp.

[Examples 13 to 17, Comparative Example 8]
For Examples 13 and 14, the extruder of Extruder Design-1 was used, for Example 15 and Comparative Example 8, the extruder of Extruder Design-2, and for Examples 16 and 17, the extruder Design- Using the extruder No. 3, melt kneading was performed at a rotation speed of 300 rpm to obtain pellets, and then various evaluations were performed. Table 5 shows the results.
In addition, Example 3 was reprinted to facilitate understanding of the difference depending on the type of filler.

  The final compositions of Examples 3 and 15 to 17 and Comparative Example 8 are the same. However. In comparison between Examples 3 and 15 and Comparative Example 8, it can be seen that the location of the cellulose greatly changes and the characteristics also greatly differ depending on the addition position of the cellulose and the addition position of the elastomer component. It is presumed that the location is salinated due to the difference in the state of the polymer when kneading the cellulose and the polymer.

  Also, although the extruder design is different between Example 3 and Examples 16 and 17, the dispersed particle size of the elastomer is much finer in Examples 16 and 17 than in Example 3. It can be seen that the particle size uniformity has also increased. From the influence, it can be seen that the strain at the time of tensile fracture, which is a measure of toughness, is greatly increased.

[Examples 18 and 19]
Using an extruder of Extruder Design-2, mixing was performed at the ratios shown in Table 6, melt-kneading was performed at a screw rotation speed of 300 rpm, and pellets were obtained. Table 6 shows the results. Examples 18 and 19 are compositions in which conductive carbon black was added to Examples 9 and 10, respectively, and thus Examples 9 and 10 were repeated.

  The resin composition of the present embodiment has sufficient characteristics even when it is made conductive, and is considered to have performance as an automotive exterior material.

  The resin composition of the present invention, for example, low specific gravity, low thermal expansion, low anisotropy, and high toughness, simultaneously achieve the contradictory properties, has sufficient physical property stability to withstand practical use, stable It can be suitably used in the field of exterior materials for automobiles, which are large parts requiring performance.

Claims (17)

Polyamide, elastomer, and a resin composition containing cellulose,
At least a portion of the elastomer has an acidic functional group,
The polyamide and the elastomer are phase separated,
A resin composition wherein more than 50% by weight of the cellulose is present in the polyamide phase.   The resin composition according to claim 1, wherein the polyamide forms a continuous phase, and the elastomer forms a dispersed phase.   At least one polyamide 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 a mixture thereof; The resin composition according to claim 1, wherein Conforms to ISO 307, 96% strength by weight viscosity number of the polyamide as measured in sulfuric acid (V _N) is 200 or less, the resin composition according to any one of claims 1 to 3.   The resin composition according to any one of claims 1 to 4, wherein the amount of the elastomer is 1 to 50 parts by mass based on 100 parts by mass of the polyamide.   The elastomer is selected from the group consisting of an ethylene-α-olefin copolymer, a block copolymer of an aromatic vinyl compound and a conjugated diene compound, and a hydrogenated product of a block copolymer of an aromatic vinyl compound and a conjugated diene compound. The resin composition according to any one of claims 1 to 5, which is at least one kind selected from the group consisting of:   The resin composition according to any one of claims 1 to 6, wherein the elastomer is an acid anhydride-modified elastomer.   The resin composition according to any one of claims 1 to 7, wherein the elastomer is a mixture of an elastomer having an acidic functional group and an elastomer having no acidic functional group. An elastomer is present as dispersed particles in the polyamide continuous phase,
The resin composition according to any one of claims 1 to 8, wherein the dispersed particles have a number average particle diameter of 3 µm or less. An elastomer is present as dispersed particles in the polyamide continuous phase,
The resin composition according to any one of claims 1 to 9, wherein the dispersed particles have a volume ratio of particles having a particle diameter of 1 µm or more and 30% by volume or less.   The resin composition according to any one of claims 1 to 10, wherein the amount of cellulose is 0.1 to 30% by mass relative to 100% by mass of the resin composition.   Cellulose is a cellulose nanofiber having a diameter of 50 to 1000 nm, L / D 30 or more, a cellulose nanocrystal having a diameter of 100 nm or less, less than L / D30, a cellulose microfiber having a diameter of more than 1 μm to 50 μm, or a mixture of two or more thereof. The resin composition according to any one of claims 1 to 11.   The resin composition according to claim 12, wherein the amount of the cellulose microfiber is 0.1 to 20% by mass relative to 100% by mass of the resin composition.   The resin composition according to any one of claims 1 to 13, wherein the cellulose is a hydrophobized cellulose.   The resin composition according to claim 1, further comprising a conductive carbon-based filler.   The resin composition according to any one of claims 1 to 15, wherein a thermal expansion coefficient at 20 ° C to 100 ° C is 50 ppm / k or less.   A molded article comprising the resin composition according to claim 1.