JP2021138971A - 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 physical stability.

Thermoplastic resins are light and have excellent processing characteristics, and are therefore widely used in various fields such as automobile parts, electrical / electronic parts, office equipment housings, and precision parts. Especially in the automobile industry, metal members have been replaced with resin members in order to improve fuel efficiency. In recent years, in regions centered on China and Europe, the transition to electric vehicles has begun to be promoted rapidly, and the development of electric vehicles has begun to be actively carried out. Therefore, in order to extend the cruising range of electric vehicles, it is becoming an urgent task to reduce the weight of the vehicle. Substitution from metal members to resin members is effective for reducing the weight of automobiles, and in particular, the use of resin for exterior parts with a large volume contributes significantly to weight reduction, so automobile manufacturers are stepping up their efforts.

As resin exterior parts, polypropylene-based materials are widely used mainly for bumpers and the like. Further, for the fender which is a vertical component, the use of a polyamide / polyphenylene ether alloy material as described in Patent Document 1 is being studied in terms of rigidity, heat resistance and the like. Further, with the aim of further improving the dimensional accuracy, for example, in Patent Documents 2 and 3, consideration is made to add an inorganic filler.

International Publication No. 2002/094936 International Publication No. 2006/077818 Japanese Unexamined Patent Publication No. 2006-199748

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

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

In order to suppress the coefficient of thermal expansion, a technique of blending an inorganic filler can be considered. However, the material obtained by this technology loses the weight reduction effect due to the fact that the parts are made of resin members due to the addition of the inorganic filler with high specific gravity, the impact strength is reduced, and the product is warped or anisotropic. In addition, it has new problems such as inferior stability of physical properties, so that it has not been widely adopted at present.

On the other hand, since the horizontal parts of automobiles (for example, bonnets, roofs, etc.) are large, further improvement in thermal expansion and anisotropy is required, and the replacement of metal members with resin members has not progressed. Is the reality.

That is, at present, no material has been obtained that achieves the contradictory physical properties of low specific density, 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 in which low specific gravity, low coefficient of thermal expansion, low anisotropy, high toughness and high physical characteristics stability are simultaneously achieved.

As a result of proceeding with studies in order to solve the above problems, the present inventors include polyamide as a thermoplastic resin, an elastomer having at least a part having an acidic functional group, and cellulose, and cellulose is mainly used as a polyamide phase. It has been found that a resin composition that exists selectively can solve the above-mentioned problems, and the present invention has been made.

That is, the present invention includes the following aspects.
[1] A resin composition containing polyamide, an elastomer, and cellulose.
At least part of the elastomer has an acidic functional group
The polyamide and the elastomer are phase-separated.
A resin composition in which more than 50% by mass of the cellulose is present in the polyamide phase.
[2] The resin composition according to the above aspect 1, wherein the polyamide forms a continuous phase and the elastomer forms a dispersed phase.
[3] The 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 one or more.
[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 the above aspects 1 to 5, which is one or more 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 the above 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 continuous phase of polyamide.
The resin composition according to any one of the above 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 continuous phase of the polyamide.
The resin composition according to any one of the above aspects 1 to 9, wherein the dispersed particles have a volume ratio of 30% by volume or less of particles having a particle diameter of 1 μm or more.
[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 with respect to 100% by mass of the resin composition.
[12] Cellulose having a diameter of 50 to 1000 nm and L / D30 or more, a cellulose nanofiber having a diameter of 100 nm or less and 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 cellulose microfibers is 0.1 to 20% by mass with respect to 100% by mass of the resin composition.
[14] The resin composition according to any one of the above aspects 1 to 13, wherein the cellulose is hydrophobic cellulose.
[15] The resin composition according to any one of the above aspects 1 to 14, further comprising a carbon-based filler for conductivity.
[16] The resin composition according to any one of the above 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 product comprising the resin composition according to any one of the above aspects 1 to 16.

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

FIG. 1 is a microscopic image showing an example of cellulose nanocrystals. FIG. 2 is a microscopic image showing an example of cellulose nanofibers. FIG. 3 is a microscopic image showing an example of cellulose microfiber. FIG. 4 is a schematic view showing the shape of a fender produced for evaluating the defect rate of a fender in Examples and Comparative Examples. FIG. 5 is a diagram of a fender showing a position where a test piece was taken out in order to measure the coefficient of variation of the linear expansion coefficient of the actual molded product in Examples and Comparative Examples.

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

The resin composition of the present invention contains polyamide, elastomer, and cellulose. At least some of the elastomers have acidic functional groups. The polyamide and elastomer are phase-separated, and more than 50% by mass of cellulose is present 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, the resin composition relating to the two-phase structure of the polyamide phase and the elastomer phase, which is a typical aspect of the present embodiment, will be described below. do.

The phase form of the resin composition of the present embodiment includes a form in which polyamide forms a continuous phase and an elastomer forms a dispersed phase, a form in which polyamide forms a dispersed phase and an elastomer forms a continuous phase, and a form in which the polyamide and the elastomer form a continuous phase. There may be a form in which both of the above form a continuous phase (that is, a co-continuous phase structure), but the form in which the polyamide forms a continuous phase and the elastomer forms a dispersed phase expresses good heat resistance as a composition. , Preferable in terms of increasing rigidity.

Generally, since cellulose has hydrophilicity, it is considered to have high affinity with, for example, acid-modified (that is, having an acidic functional group) elastomer and polyamide. Further, it is considered that the finely divided cellulose may be entangled with a highly viscous elastomer component. Further, it is known that the position of the hydrophobized cellulose, which will be described later, in the resin composition changes depending on the kneading conditions due to the decrease in hydrophilicity.

The lower limit of the ratio of cellulose present in the polyamide phase to the cellulose in the resin composition of the present embodiment is more than 50% by mass, preferably 60% by mass, more preferably 70% by mass, and further. It is preferably 75% by weight, even more preferably 80% by weight, and most preferably 100% by weight (ie, substantially all cellulose is present in the polyamide phase). By setting the above ratio within the above range, it is possible to simultaneously achieve various contradictory characteristics such as low thermal expansion, low anisotropy, and high toughness. The upper limit of the above 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 abundance ratio of cellulose is significantly different between the polyamide phase and the elastomer phase, the resin composition does not need to be quantified. It can be easily confirmed by photographing the object 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. If quantification is required, the resin composition is sliced to a thickness of about 0.1 to 2 μm to obtain a film-like sample. The sample is immersed in a solvent that dissolves the elastomer component but does not dissolve polyamide (for example, chloroform, toluene, etc.) to elute the elastomer phase, concentrate the eluate, and then perform ultracentrifugation to be present in the elastomer phase. The cellulose to be used is separated, and then washing with a solvent is repeated at least 3 times, dried, and the amount of cellulose present in the elastomer phase is measured.

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

<< Polyamide >>
Examples of the polyamide used in the present invention include a polycondensate of dibasic acid and diamine, a cyclic lactam ring-opening polymer, a polycondensate of aminocarboxylic acid, and a copolymer and a blend thereof. More specifically, aliphatic polyamides such as polyamide 6, polyamide 10, polyamide 11, polyamide 12, polyamide 46, polyamide 66, polyamide 610, and polyamide 612, polymethoxylen adipamide (polyamide MXD6), and polyhexamethylene tele. Aromatic polyamide resins such as phthalamide (polyamide 6T) and polyhexamethyleneisophthalamide (polyamide 6I), and polyamide 6/6I, polyamide 66 / 6I, polyamide 6 / 6T, polyamide 66 / 6T, polyamide 6/66. Copolymers and blends such as / 6T, polyamide 6/66 / 6I, polyamide 9T, and polyamide 10T can be used. Among these, polyamide 6, polyamide 10, polyamide 11, polyamide 12, polyamide 66, polyamide 610, polyamide 612, polyamide 6 / 6I, polyamide 66 / 6I, polyamide 6I, and blends thereof are particularly preferable. .. Most preferably, polyamide 6, polyamide 66, polyamide 610, polyamide 612, polyamide 6I, and blends thereof.

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

In polyamide, the ratio of carboxyl terminal groups to total terminal groups ([COOH] / [total terminal groups]) is preferably 0.30 to 0.95. The lower limit of the carboxyl-terminal 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, even more preferably 0.85, and most preferably 0.80. The carboxyl-terminal group ratio is preferably 0.30 or more from the viewpoint of dispersibility of cellulose in the resin composition, and is preferably 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, diamine compounds, monoamine compounds, dicarboxylic acid compounds, monocarboxylic acid compounds, acid anhydrides, monoisocyanates, monoacid halides, monoesters, monoalcohols, etc. Examples thereof include a method of adding an end modifier that reacts with an end group to the polymerization solution.

Examples of the terminal modifier that reacts with the terminal amino group include acetic acid, propionic acid, butylic acid, valeric acid, caproic acid, capric acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutylic acid. And other aliphatic monocarboxylic acids; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid. Carboxylic acids; and a plurality of mixtures arbitrarily selected from these. Among these, acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, etc. One or more end regulators selected from the group consisting of valeric acid and valeric acid are preferable, and acetic acid is most preferable.

Examples of the terminal modifier that reacts with the terminal carboxyl group include aliphatic groups 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 and naphthylamine and any mixtures thereof. Among these, one or more terminals selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine and aniline from the viewpoints of reactivity, boiling point, stability of sealing terminal, price and the like. Regulators are preferred.

The concentrations of these amino-terminal groups and carboxyl-terminal groups are preferably obtained by ¹ H-NMR from the integrated value of the characteristic signal corresponding to each terminal group in terms of accuracy and simplicity. As a method for determining the concentration of these terminal groups, specifically, the method described in JP-A-7-228775 is recommended. When this method is used, ditrifluoroacetic acid is useful as the measurement solvent. In addition, the ^{number of integrations of 1 1} H-NMR requires at least 300 scans even when measured with a device having sufficient resolution. In addition, the concentration of the terminal group can also be measured by a measurement method by titration as described in JP-A-2003-055549. However, in order to reduce the influence of mixed additives, lubricants, etc. as much as possible, ¹ H-NMR quantification is more preferable.

The polymerization degree of the polyamide is not particularly limited, in terms of conventional injection molding processability, conforms to ISO 307, 96% strength by weight viscosity number of the polyamide was measured in sulfuric acid (V _N) is, is 200 or less 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 of the molded product during molding can be appropriately maintained, and the molding strain can be reduced, so that the anisotropy of the actual molded product can be suppressed to a low level. The lower limit of the degree of polymerization is not particularly limited, but from the viewpoint of obtaining good impact resistance, it is preferably 50, more preferably 60, more preferably 65, and most preferably 70.

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

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

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

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

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

The aromatic compound-conjugated diene block copolymer referred to here is a block 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 binding form of each block is any of AB type, ABA type, and ABAB type is preferable from the viewpoint of developing impact strength, and more preferably ABBA type or ABAB type.

Further, it is desirable that the mass ratio of the aromatic vinyl compound and the conjugated diene compound in the block copolymer is 10/90 to 70/30. More preferably, it is 15/85 to 55/45, and most preferably 20/80 to 45/55. Further, two or more kinds of these 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, and one or more compounds selected from these are used, and styrene is particularly preferable.

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 butadiene is used as the conjugated diene compound of the block copolymer, the microstructure of the polybutadiene block portion may be 1,2-vinyl content or 1,2-vinyl content from the viewpoint of suppressing the crystallization of soft segments. The total amount with the 3,4-vinyl content is preferably 5 to 80%, more preferably 10 to 50%, and most preferably 15 to 40% on a molar basis.

Further, the hydrogenated additive of the block copolymer of the aromatic vinyl compound and the conjugated diene compound is mainly composed of the diene compound by hydrogenating the block copolymer of the aromatic vinyl compound and the conjugated diene compound described above. This refers to a compound in which the aliphatic double bond of 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 deterioration during processing.

Further, as the molecular weights 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 10,000 to 10,000 from the viewpoint of achieving both impact strength and fluidity. 500,000 is preferable, and 40,000 to 250,000 is most preferable. The number average molecular weight referred to here is a value measured by a gel permeation chromatography apparatus using chloroform as a solvent at a measurement temperature of 40 ° C. and converting with a polystyrene standard.

Block copolymers of these aromatic vinyl compounds-conjugated diene compounds have different bonding forms, different molecular weights, different aromatic vinyl compound species, different conjugated diene compound species, and 1,2-vinyl content. Alternatively, two or more kinds of compounds having different total amounts of 1,2-vinyl content and 3,4-vinyl content, different aromatic vinyl compound component contents, different hydrogen addition rates, etc. are used in combination. It doesn't matter.

Further, as the polyolefin, an ethylene-α-olefin copolymer can be preferably used from the viewpoint of exhibiting impact resistance. Monomers that can be copolymerized with ethylene units include propylene, butene-1, pentene-1, 4-methylpentene-1, hexene-1, heptene-1, octene-1, nonen-1, decene-1, and undecene-1. , Dodecene-1, tridecene-1, tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1, octadecene-1, nonadecene-1, eicosen-1, isobutylene and other aliphatic substituted vinyl monomers, and styrene. , Aromatic vinyl monomers such as substituted styrene, vinyl acetate, acrylic acid ester, methacrylic acid ester, glycidyl acrylate ester, glycidyl methacrylic acid ester, acrylate vinyl monomer such as hydroxyethyl methacrylic acid ester, acrylamide, allylamine , Nitrogen-containing vinyl monomers such as vinyl-p-aminobenzene and acrylonitrile, and diene such as butadiene, cyclopentadiene, 1,4-hexadiene and 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, and most preferably ethylene. It is a copolymer with one or more α-olefins having 3 to 12 carbon atoms. The molecular weight of the ethylene-α-olefin copolymer was measured with a gel permeation chromatography measuring device at 140 ° C. using polystyrene standard using 1,2,4-trichlorobenzene as a solvent from the viewpoint of developing impact resistance. The number average molecular weight (Mn) obtained is preferably 10,000 or more, more preferably 10,000 to 100,000, and further 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 achieving both fluidity and impact resistance.

The content of the ethylene unit of the ethylene-α-olefin copolymer is preferably 30 to 95% by mass with respect to the total amount of the ethylene-α-olefin copolymer from the viewpoint of handleability during processing.

These preferable ethylene-α-olefin copolymers are, for example, JP-A-4-12833, JP-A-60-35006, JP-A-60-35007, JP-A-60-3508, and JP-A. It can be produced by the production method described in Kaihei 5-155930, JP-A-3-163088, US Pat. No. 5,272,236, and the like.

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

In the elastomer of the present embodiment, at least a part of the elastomer has an acidic functional group. In the present disclosure, the fact that the elastomer has an acidic functional group means that the acidic functional group is added to the molecular skeleton of the elastomer via a chemical bond. Further, 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, an acid anhydride group and the like. Can be mentioned.

The amount of the acidic functional group added to the elastomer is preferably 0.01% by mass or more, more preferably 0.1% by mass or more, still more preferably 0, based on 100% by mass of the elastomer from the viewpoint of compatibility with polyamide. .2% by mass or more, preferably 5% by mass or less, more preferably 3% by mass or less, still more preferably 2% by mass or less. The number of acidic functional groups is determined based on the calibration curve prepared by measuring a calibration curve sample mixed with an acidic substance in advance with an infrared absorption spectrum measuring device and using the characteristic absorption band of the acid. It 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 copolymerization component as a shell, an ethylene-α olefin copolymer containing acrylic acid or the like as a monomer, a polyolefin, and an aroma. An α, β-unsaturated dicarboxylic acid or a derivative thereof is grafted onto a hydrogenated product of a group compound-conjugated diene copolymer or an aromatic compound-conjugated diene copolymer in the presence or absence of a peroxide. Examples thereof include an elastomer which is a modified product.

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

Among these, α, β-non-existent in the presence or absence of a peroxide in the hydrogenated additive of a polyolefin, an aromatic compound-conjugated diene copolymer, or an aromatic compound-conjugated diene copolymer. Modified products obtained by grafting a saturated dicarboxylic acid or a derivative thereof are more preferable, and the presence of peroxide is particularly present in the hydrogenated product of the ethylene-α-olefin copolymer or the aromatic compound-conjugated diene block copolymer. Modified products grafted with α, β-unsaturated dicarboxylic acid and derivatives thereof in the presence or absence are particularly preferable.

Specific examples of α, β-unsaturated dicarboxylic acid and its derivative include maleic acid, fumaric acid, maleic anhydride, and fumaric anhydride, and maleic anhydride is particularly preferable among them.

The elastomer may have at least a part thereof having 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. When the mixing ratio of the elastomer having an acidic functional group and the elastomer not having an acidic functional group is 100% by mass in total, the elastomer having an acidic functional group has high toughness and physical stability of the resin composition. From the viewpoint of maintaining a good condition, the content is preferably 10% by mass or more, more preferably 20% by mass, still more preferably 30% by mass, and most preferably 40% by mass. There is no particular upper limit, and substantially all elastomers may be elastomers having an acidic functional group, but 80% by mass or less is desirable from the viewpoint of not causing a problem in fluidity.

In the resin composition, the amount of elastomer with respect to 100 parts by mass of 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 content is not more than the above upper limit. The lower limit is more preferably 2 parts by mass, further preferably 3 parts by mass, still more preferably 4 parts by mass, and most preferably 5 parts by mass. In order to enhance the toughness and physical stability of the resin composition, it is preferably at least the above lower limit.

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 the number average particle diameter. It is as follows. The lower limit is not particularly limited, but is, for example, 0.1 μm. From the viewpoint of high toughness and physical stability, it is preferably within the above range.

The elastomer preferably has high uniformity of dispersed particle size. From this viewpoint, it is preferable that the volume ratio of the dispersed particles having a particle diameter of 1 μm or more to the entire dispersed particles of the elastomer is 30% by volume or less. The upper limit is more preferably 25% by volume, even more preferably 20% by volume, even more preferably 15% by volume, and most preferably 10% by volume. In the distributed particle size distribution on a volume basis, even if the number is very small, the volume ratio of the dispersed particles having a particle size of 1 μm or more is expressed in a large size at once in the presence of coarse particles. When the volume ratio is within the above range, the uniformity of the dispersed particle size is high, which is preferable. From the viewpoint of ease of production of the resin composition, the volume ratio may be, for example, 2% by volume or more, or 5% by volume or more.

As a method for increasing the uniformity of the dispersed particle size of the elastomer, a resin composition is produced by extrusion-kneading the compounding components of the resin composition, and the screw rotation speed during extrusion-kneading is increased to increase the shear strain in the compounding components. A method of finely dispersing the elastomer by giving a method, for example, a method of arranging screw parts such as a seal ring in which a narrow clearance exists uniformly to give a stretch flow strain to the compounding component, a method of passing a special narrow slit through a molten polymer, and allowing the molten polymer to pass through a special narrow slit. Examples thereof include a method of applying stretch flow strain at the slit portion, and any of these methods may be used. However, in the method of applying high shear, the polymer temperature rises remarkably during processing, so a method using stretch flow strain is used. Is more preferable.

As a method of observing the dispersed morphology, a method of cutting a resin composition in the form of a molded product, pellets, etc. as an ultrathin section, dyeing the polyamide phase with phosphotensive acid or the like, and then observing with a transmission electron microscope. After the surface of the resin composition in the form of a molded product, pellet, etc. is uniformly surfaced, the resin composition is immersed in a solvent that selectively dissolves only the elastomer, the elastomer is extracted, and the resin composition is observed with a scanning electron microscope. Can be mentioned. The obtained image is binarized by an image analyzer, the diameter of the dispersed particles in the dispersed phase (at least 500 randomly selected) is calculated as the equivalent circle diameter, and the respective particle diameters are counted to obtain the dispersed particles. It is possible to calculate the number average particle diameter and the volume ratio of particles having a predetermined particle diameter (for example, the above particle diameter of 1 μm or more).

<< Cellulose >>
Next, the cellulose that can be used in this embodiment will be described in detail.
The amount of cellulose that can be used in this embodiment is preferably in the range of 0.1 to 30% by mass when the entire resin composition is 100% by mass. A more preferable upper limit value is 25% by mass, even more preferably 20% by mass, and most preferably 15% by mass. The lower limit is more preferably 0.5% by mass, even 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 preferably within the above range.

The cellulose in the present embodiment is cellulose nanofibers having a diameter of 50 to 1000 nm and an L / D of 30 or more, cellulose nanofibers having a diameter of 100 nm or less and an L / D of less than 30, cellulose microfibers having a diameter of more than 1 μm to 50 μm, or these. It is desirable that it is a mixture of.

Examples of the cellulose that can be used in this embodiment include natural cellulose and regenerated cellulose. Natural cellulose includes wood pulp obtained from wood species (hardwood or coniferous tree), non-wood pulp obtained from non-wood species (bamboo, hemp fiber, bagasse, kenaf, linter, etc.), and refined pulp (refined linter) thereof. Etc.) etc. can be used. As the non-wood pulp, cotton-derived pulp containing 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 cotton lint, cotton linter, hemp-based abaca (eg, from Ecuador or Philippines), and zeal, respectively. , Bagasse, Kenaf, Bamboo, Walla, etc., and finely divided cellulose from refined pulp obtained through purification steps such as delignin by cooking treatment, bleaching steps, and the like.

The cellulose nanocrystal (hereinafter, may be referred to as CNC) in the present embodiment is made from the above-mentioned pulp as a raw material, cut, and then dissolved in an acid such as hydrochloric acid or sulfuric acid to dissolve an amorphous portion of cellulose. Residual 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, 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, still more preferably 10 or less. The L / D ratio is 1 or more, preferably 2 or more, more preferably 4 or more, still more preferably 5 or more.

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

Cellulose nanofibers (hereinafter sometimes referred to as CNF) are obtained by treating the above-mentioned pulp with hot water or the like at 100 ° C. or higher, hydrolyzing the hemicellulose portion to make it fragile, and then using a high-pressure homogenizer or microfluy. Refers to cellulose deflated by a crushing method such as a dither, ball mill, or disc mill. The diameter of CNF is 50 to 1000 nm. The diameter of the CNF is more preferably 5 nm or more, further preferably 10 nm or more, still more preferably 40 nm or less, still more preferably 20 nm or less. The L / D of CNF is 30 or more, preferably 50 or more, more preferably 80 or more, still more preferably 100 or more, preferably 5000 or less, more preferably 4000 or less, still more preferably 3000 or less. be.

FIG. 2 is a microscopic image showing an example of cellulose nanofibers. It can be seen that each cellulose has a fibrous structure, has a diameter of 50 to 1000 nm, and has an L / D of 30 or more.

Further, the cellulose microfiber (hereinafter, may be referred to as CMF) refers to a relatively large-sized fibrous cellulose obtained by reducing the number of defibration steps in the process of producing CNF. The diameter of the CMF is more than 1 μm to 50 μm. The diameter of the CMF is preferably 2 μm or more, more preferably 5 μm or more, still more preferably 10 μm or more, preferably 45 μm or less, more preferably 40 μm or less, still more preferably 35 μm or less. The L / D of CMF is preferably 30 or more, more preferably 50 or more, still more preferably 70 or more, preferably 2000 or less, more preferably 1000 or less, still more preferably 500 or less. CMF is usually obtained with about half the energy for producing CNF.

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

Preferred embodiments of cellulose in the present embodiment include CNF alone, CMF alone, CNF and CNC used in combination, CNF and CMF used in combination, and CMF, from the viewpoint of ensuring physical stability. The combined use of two types of CMF and CNC, and the combined use of three types of CMF, CNF and CNC can be mentioned. More preferred embodiments include single use of CMF, combined use of two types of CNF and CNC, combined use of two types of CNF and CMF, combined use of two types of CMF and CNC, and combined use of three types of CMF, CNF and CNC. Use is mentioned.

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

Further, when the two types of CNF and CNC are used in combination and when the two types of CMF 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. be. The upper limit of the above ratio is more preferably 97% by mass, further preferably 95% by mass, still more preferably 93% by mass, and most preferably 90% by mass. The lower limit of the above ratio is more preferably 55% by mass, even more preferably 60% by mass, and most preferably 70% by mass.

Further, when the three types 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 above ratio is more preferably 97% by mass, further preferably 95% by mass, still more preferably 93% by mass, and most preferably 90% by mass. The lower limit of the above ratio is more preferably 55% by mass, even more preferably 60% by mass, and most preferably 65% by mass. Further, when the total amount of cellulose other than CNC is 100% by mass, the preferable ratio of CMF is 50 to 99% by mass. The upper limit of the above ratio is more preferably 97% by mass, further preferably 95% by mass, still more preferably 93% by mass, and most preferably 90% by mass. The lower limit of the above ratio is more preferably 55% by mass, even more preferably 60% by mass, and most preferably 70% by mass.

The amount of CMF with respect to 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, it is possible to improve characteristics such as tensile elongation and vibration fatigue characteristics. The lower limit of the above amount is more preferably 1% by mass, further preferably 2% by mass, even more preferably 3% by mass, and most preferably 5% by mass. The upper limit is more preferably 18% by mass, 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 such that each aqueous dispersion of CNC and CNF is used as a high-shear homogenizer (for example, manufactured by Nippon Seiki Co., Ltd., trade name "Excel Auto". Using a homogenizer ED-7 "), the treatment condition: an aqueous dispersion dispersed at a rotation speed of 15,000 rpm x 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 with 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 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 (L / D) of 30 or more are classified as CNF. For each of the CNC and the CNF, the number average value of the length (L), the number average value of the diameter (D), and the number average value of the ratio (L / D) are calculated, and the numbers of the CNC and the CNF of the present disclosure are calculated. Each length, diameter, and L / D ratio. The length and diameter of the celluloses disclosed in the present disclosure are the average value of the numbers of the above 100 celluloses.

Since the size scale of CMF is different from that of 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 water dispersion prepared so that the CMF is about 0.1% by mass with an ultrasonic cleaner, or the disperser (for example, Despamill Asada Iron Works Co., Ltd.) is used. The dispersion treatment is carried out for 20 minutes to disentangle the CMFs, and then the aqueous dispersion is observed as it is with an optical microscope. The measurement / 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 such that the polymer component in the composition is dissolved in an organic or inorganic solvent capable of dissolving the polymer component of the composition. After separating cellulose and thoroughly washing with the above 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 as described above. The measurement is performed by the method of.

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

The volume average particle diameter is a value obtained by a laser diffraction / scattering method particle size distribution meter as a spherical equivalent diameter (volume average particle diameter) of particles when the integrated volume becomes 50%. Specifically, the solid content of the sample is 40% by mass, and in a planetary mixer (for example, 5DM-03-R manufactured by Shinagawa Kogyo Co., Ltd., the stirring blade is a hook type) at 126 rpm, 30 at room temperature and normal pressure. Knead for minutes, then make a pure water suspension at a concentration of 0.5% by mass, and use a high shear homogenizer (for example, manufactured by Nippon Seiki Co., Ltd., trade name "Excel Auto Homogenizer ED-7" processing conditions), and rotate the number of revolutions. Disperse at 15,000 rpm x 5 minutes and use a centrifuge (for example, manufactured by Kubota Shoji Co., Ltd., trade name "6800 type centrifuge", rotor type RA-400 type), processing conditions: centrifugal force 39200 m ² / The supernatant collected by centrifuging at s for 10 minutes 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 method particle size distribution meter (for example, manufactured by Horiba Seisakusho Co., Ltd., trade name "LA-910" or trade name "LA-950", ultrasonic treatment 1 minute, refractive index 1. The integrated 50% particle diameter in the volume frequency particle size distribution obtained in 20) (that is, the spherical equivalent diameter of the particles when the integrated volume becomes 50% with respect to the total volume of the particles) is defined as the volume average particle diameter. ..

The degree of polymerization of cellulose in the present disclosure is the average degree of polymerization measured according to the reduction specific viscosity method using a copper ethylenediamine solution described in the confirmation test (3) of the "15th revised Japanese Pharmacopoeia Manual (published by Hirokawa Shoten)". Is.

Examples of the method for controlling the degree of polymerization (that is, the average degree of polymerization) of cellulose include hydrolysis treatment and the like. By the hydrolysis treatment, the amorphous cellulose inside the cellulose fiber is depolymerized, and the average degree of polymerization is reduced. 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. As a result, in the step of applying a mechanical shearing force to the cellulose, such as during the kneading step described later, the cellulose is easily subjected to mechanical treatment, and the cellulose is easily refined.

The method of hydrolysis is not particularly limited, and examples thereof include acid hydrolysis, alkali hydrolysis, hot water hydrolysis, steam explosion, and microwave hydrolysis. These methods may be used alone or in combination of two or more. In the acid hydrolysis method, for example, α-cellulose obtained as 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, heteropolyacid, etc. is added. In addition, the average degree of polymerization can be easily controlled by heating while stirring. The reaction conditions such as temperature, pressure, and time at this time differ depending on the cellulose type, cellulose concentration, acid type, acid concentration, and the like, but are appropriately adjusted so as to achieve the desired average degree of polymerization. For example, there is a condition that cellulose is treated for 10 minutes or more under pressure at 100 ° C. or higher using an aqueous mineral acid solution of 2% by mass or less. Under this condition, the catalyst component such as acid permeates into the inside of the cellulose fiber and hydrolysis is promoted, so that the amount of the catalyst component used can be reduced and the subsequent purification becomes easy. In addition to water, the dispersion liquid of the cellulose raw material at the time of hydrolysis may contain a small amount of an organic solvent as long as the effect of the present invention is not impaired.

≪Cellulose hydrophobicity≫
The cellulose in this embodiment may be cellulose hydrophobized by a hydrophobizing agent. By making the cellulose hydrophobic, the hydrogen bond between the celluloses is weakened, which contributes to fine dispersion, the heat resistance of the cellulose is improved, and the deterioration due to kneading with the resin can be suppressed, so that the cellulose has physical characteristics. It has the effect of making it less likely to be the starting point of defects.

As the hydrophobizing agent, a compound that reacts with the hydroxyl group of cellulose can be used, and examples thereof include an esterifying agent, an etherizing agent, and a silylating agent. Especially an esterifying agent is preferable.

As the esterifying agent, acid chlorides, acid anhydrides, and carboxylic acid vinyl esters are preferable. 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 at the same time as 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.

The carboxylic acid vinyl ester has the following formula (1):
R-COO-CH = CH ₂ ... Equation (1)
{In the formula, R is either 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, or an aryl group having 6 to 16 carbon atoms. } Is preferable. Vinyl carboxylic acid esters include vinyl acetate, vinyl propionate, vinyl butyrate, vinyl caproate, vinyl cyclohexanecarboxylic acid, vinyl caprylate, vinyl caprate, vinyl laurate, vinyl myristate, vinyl palmitate, vinyl stearate, and pivalin. More preferably, it is at least one selected from the group consisting of vinyl acid acid, vinyl octylate divinyl adipate, vinyl methacrylate, vinyl crotonate, vinyl pivalate, vinyl octylate, vinyl benzoate, and vinyl silicate. .. 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, at least one selected from the group consisting of acetic anhydride, propionic anhydride, butyric anhydride, vinyl acetate, vinyl propionate, and vinyl butyrate, among which acetic anhydride and vinyl acetate have reaction efficiencies. It is preferable from the viewpoint of.

The method for refining the natural cellulose raw material to reduce the fiber diameter is not particularly limited, but it is preferable to make the defibration treatment conditions (method of providing a shear field, size of the shear field, etc.) more efficient. In particular, by impregnating a cellulose raw material having a cellulose purity of 85% by mass or more with a solution for defibration containing an aprotic solvent, swelling of cellulose occurs in a short time, and cellulose is given only a slight stirring and shearing energy. Is becoming finer. Then, hydrophobicized cellulose can be obtained by adding a cellulose modifier immediately after defibration. This method is preferable from the viewpoint of production efficiency and purification efficiency (that is, high cellulose purification of hydrophobic cellulose), and physical characteristics of the resin complex.

Examples of the aprotic solvent include alkyl sulfoxides, alkyl amides, pyrrolidones and the like. These solvents can be used alone or in combination of two or more.

Examples of alkyl sulfoxides include diC1-4 alkyl sulfoxides such as dimethyl sulfoxide (DMSO), methyl ethyl sulfoxide, and diethyl sulfoxide.

Examples of alkylamides include N, N-diC1-4 alkylformamides such as N, N-dimethylformamide (DMF) and N, N-diethylformamide; N, N-dimethylacetamide (DMAc), N, N. Examples thereof include N, N-di C1-4 alkylacetamide such as -diethylacetamide.

Examples of pyrrolidones include pyrrolidones such as 2-pyrrolidone and 3-pyrrolidone; and N-C1-4 alkylpyrrolidones 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 (numbers in parentheses are the number of donors), DMSO (29.8), DMF (26.6), DMAc (27.8), NMP (27.3), etc., especially DMSO. Can be used to more efficiently produce hydrophobicized cellulose having a high thermal decomposition start temperature. The mechanism of action is not always clear, but it is presumed to be due to the homogeneous microswelling of the fiber raw material in the aprotic solvent.

When the cellulose raw material swells in an aprotic solvent, the aprotic solvent quickly permeates and swells into the fibrils constituting the raw material, so that the microfibrils are in a finely defibrated state. After creating this state, it is presumed that by chemically modifying the fine fibers, hydrophobicity progresses uniformly throughout the fine fibers, and as a result, high heat resistance is obtained. In addition, the microfibrillated chemically modified microfibers maintain a high degree of crystallinity, providing high mechanical properties and excellent dimensional stability (particularly a significant decrease in the coefficient of linear thermal expansion) when combined with a resin. Can be acquired.

The finely divided (defibrated) and hydrophobized cellulose is subjected to impact shearing devices such as planetary ball mills and bead mills, and rotary shearing fields such as discifiers and grinders that induce fibrilization of cellulose. It can be obtained by using an apparatus capable of performing kneading, stirring, and dispersing functions with high efficiency, such as various kneaders and planetary mixers.

In the reflective infrared absorption spectrum of hydrophobized cellulose, the peak position of the absorption band changes depending on the type of 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. In addition, the modification rate can be calculated from the peak intensity ratio of 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 absorption band of C = O based on the ester group ^{appears at 1730 cm -1} , the peak of the absorption band of CH based on the cellulose skeleton chain is 1370 cm ^-1 , and cellulose. The peak of the absorption band of CO based on the skeletal chain appears at ^{1030 cm -1.}

When the hydrophobic modifying group of hydrophobicized cellulose is an ester group, the peak intensity of the absorption band based on the chemically modifying group with respect to the peak intensity (height) of the absorption band of the cellulose skeleton chain CH in the IR spectrum measured by the reflection type. Modification defined by the ratio of (peak height of absorption band of C = O based on ester group) (peak height of absorption band based on chemical modification group / peak height of absorption band of cellulose skeleton chain CH) The conversion rate (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 complex containing hydrophobic cellulose having a high thermal decomposition start temperature can be obtained. On the other hand, when it is 1.8 or less, an unmodified cellulose skeleton remains in the hydrophobicized cellulose, so that the hydrophobicity has high tensile strength and dimensional stability derived from cellulose and a high thermal decomposition start temperature derived from chemical modification. 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, still more preferably 1.5 or less.

Further, the ratio (chemical modification) of the peak intensity of the absorption band based on the chemically modifying group (the peak height of the absorption band of C = O based on the ester group) to the peak intensity (height) of the absorption band of the cellulose skeleton chain CH (chemical modification). 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 skeleton chain CO) is 0.13 or more and 0.48 or less. preferable. When the IR index 1030 is 0.13 or more, a resin complex containing hydrophobic cellulose having a high thermal decomposition start temperature can be obtained. On the other hand, when it is 0.48 or less, an unmodified cellulose skeleton remains in the hydrophobicized cellulose, so that the hydrophobicity has high tensile strength and dimensional stability derived from cellulose and a high thermal decomposition start temperature derived from chemical modification. A resin composite containing cellulose can be obtained. The IR index 1030 is more preferably 0.15 or more, still more preferably 0.17 or more, preferably 0.45 or less, more preferably 0.4 or less, still more preferably 0.35 or less.

≪Carbon-based filler for conductivity≫
In a preferred embodiment, the resin composition further comprises a conductive carbon-based filler. Thereby, a conductive resin composition can be obtained. Preferred carbon-based fillers for conductivity include carbon black, carbon fibers, graphite, graphene, carbon nanotubes and the like. The shape of these conductive carbon-based fillers may be granular, flake-like, or fibrous fillers. As specific examples of preferable conductive carbon-based fillers, conductive carbon black, carbon nanotubes (CNT), carbon fibers, graphite and the like can be preferably used, and among these, conductive carbon black and CNT are most preferable.

The amount of dibutyl phthalate (DBP) absorbed by the conductive carbon black is preferably 250 ml / 100 g or more, more preferably 300 ml / 100 g or more, and further preferably 350 ml / 100 g or more. The DBP absorption amount referred to here is a value measured by the 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. Examples of commercially available conductive carbon black include Ketjen Black EC-600JD.

The conductive carbon black referred to in the present embodiment is different from general carbon black for coloring (usually, the above-mentioned DBP absorption amount is less than 250 ml / 100 g and the BET surface area is less than 200 m ² / g), and a small amount is added. Expresses good conductivity.

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

The carbon-based filler for conductivity may be one in which the adhesion to the resin and / or the handleability is improved by treating with various known coupling agents and / or converging agents.

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

≪Agglutination inhibitor≫
Since cellulose has a characteristic that it aggregates in the drying step and is difficult to redisperse, it is preferable to use an aggregation inhibitor in order to enhance the redispersibility of cellulose when melt-kneaded with the resin. By increasing the redispersibility, the mechanical characteristics of the obtained resin composition and its stability can be improved. It is desirable that the agglutination inhibitor is added to the aqueous cellulose dispersion and then dried while applying shear to obtain a cellulose powder.

The preferable amount of the agglutination inhibitor is 2 to 100 parts by mass with respect to 100 parts by mass of cellulose. The lower limit is more preferably 4 parts by mass, even more preferably 5 parts by mass, and most preferably 6 parts by mass. The upper limit is more preferably 80 parts by mass, even more preferably 60 parts by mass, and most preferably 40 parts by mass. In order to enhance the dispersibility of cellulose in the resin and enhance the physical stability, it is desirable to keep it 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 may have a chemical structure in which a site having a hydrophilic substituent and a site having a hydrophobic substituent are covalently bonded, and is used for various purposes such as edible and industrial purposes. You can use what you have. For example, the following can be used alone or in combination of two or more.

As the surfactant, any of anionic surfactants, nonionic surfactants, amphoteric ionic surfactants, and cationic surfactants can be used, but in terms of affinity with cellulose. Therefore, anionic surfactants and nonionic surfactants are preferable, and nonionic surfactants are more preferable.

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

Among the above-mentioned surfactants, as hydrophobic groups, alkyl ether type, alkyl phenyl ether type, rosin ester type, bisphenol A type, β naphthyl type, styrenated phenyl type, and cured castor oil type have an affinity with the resin. Because of its high value, it can be preferably used. As a preferable alkyl chain length (in the case of alkylphenyl, the number of carbon atoms excluding the phenyl group), the carbon chain is preferably 5 or more, more preferably 10 or more, further preferably 12 or more, and particularly preferably 16 or more. When the resin is polyolefin, the higher the number of carbon atoms, the higher the affinity with the resin, so 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 polyfunctional structure are preferable. The alkylphenyl ether type, rosin ester type, bisphenol A type, β-naphthyl type, and styrenated phenyl type are preferable as those having a cyclic structure, and the cured castor oil type is preferable as those having a polyfunctional structure. Of these, the rosin ester type and the cured castor oil type are particularly preferable.

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

≪Coefficient of variation≫
In the resin composition of the present embodiment, the coefficient of variation CV of the tensile breaking strength is preferably 10% or less from the viewpoint of eliminating strength defects of the obtained molded product. The coefficient of variation 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 number without a unit representing the relative variation.
CV = (σ / μ) × 100
Here, μ and σ are given by the following equations.

ここで、ｘｉは、ｎ個のデータ ｘ１、ｘ２、ｘ３・・・・Ｘｎのうちの引張破断強度の単一の個データである。

Here, xi is a single piece of data on the tensile breaking strength of 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 make it easier to find the defect. More preferably, it is 15 or more.

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

Partial strength defects of conventional resin molded products are considered to be caused by non-uniform dispersion of fillers and the formation of voids. As an index for evaluating the ease of forming this strength defect, there is a method of performing a tensile test of a plurality of test pieces and confirming the presence / absence / number of variations in breaking strength.

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

It has been difficult to predict structural defects that occur in the actual product at the test stage, and for example, a method of confirming the defective portion in the product with a microscope or the like has been used. However, observation with a microscope is an extremely microscopic observation, and it is not possible to comprehensively evaluate the entire test piece and the entire product.

The present inventors have found that there is a correlation between the coefficient of variation of tensile strength at break and the ratio of structural defects in the product while proceeding with various studies.

More specifically, for example, in the case of a material having a homogeneous internal structure and no voids, even when a tensile fracture test of a plurality of samples is performed, the stress at the time of fracture is between the plurality of samples. They are almost the same value, and their coefficient of variation is very small. However, in a material having non-uniform parts, voids, etc. inside, the stress leading to fracture in one sample has a large difference from the stress in other samples. The degree of the number of samples showing a stress different from the stress of other samples can be clarified by using a scale called the coefficient of variation.

For example, in the case of a material having no yield strength, a sample having an internal defect will break at a lower strength than other samples. Further, in the case of a material having yield strength, it often breaks on the way to necking after yielding, and a sample having an internal defect breaks at a higher strength than other samples. Shows a tendency to reach. Although there are differences in behavior in this way, the possibility of strength defects in the actual product can be predicted by using the coefficient of variation of tensile strength at break.

It is considered that the dispersion state and the dispersion position of cellulose in the composition have a great influence on the coefficient of variation 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, if 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 physical stability is greatly reduced. That is, by stably dispersing cellulose in the polyamide phase, the stability of physical properties is increased.

Various methods for stably dispersing cellulose in the polyamide phase can be mentioned. As an 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 concentration of terminal groups of polyamide, and a method of optimizing the order of addition during kneading of cellulose. Method, method of weakening the affinity between the elastomer and cellulose or increasing the affinity with polyamide by adding the optimum surfactant, etc., method of melting and mixing polyamide and cellulose in advance to make a master batch, extruder Various approaches can be mentioned, 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 deterioration during kneading with a resin.

Any of these approaches may be used to stably disperse the cellulose in the polyamide phase. Setting the coefficient of variation CV of the tensile breaking strength to 10% or less can greatly contribute to the elimination of the strength defects of the obtained molded product, and has the effect of significantly improving the reliability of the strength of the molded product.

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 1.0 is preferably 1.1 times or more, more preferably 1.15 times or more, and even more. It is preferably 1.2 times or more, and most preferably 1.3 times or more. The upper limit of the above ratio is not particularly limited, but from the viewpoint of ease of manufacture, for example, it is preferably 5.0 times, more preferably 4.0 times.

Since the resin composition of the present embodiment contains cellulose, it is possible to exhibit low thermal expansion without increasing the specific gravity. Specifically, the coefficient of thermal expansion of the resin composition in the 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. Yes, most preferably 35 ppm / K or less. The lower limit of the coefficient of thermal expansion is not particularly limited, but from the viewpoint of ease of manufacture, for example, it is preferably 5 ppm / K, and more preferably 10 ppm / K.

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

When the dispersion of cellulose in the resin composition is non-uniform and the difference in linear expansion coefficient between sites is large, problems such as distortion or warpage of the molded product are likely to occur due to temperature changes. Moreover, this failure is a failure mode that occurs due to the difference in thermal expansion and reversibly occurs when the temperature rises and falls. Therefore, it can be a failure mode having a potential risk that it cannot be recognized by a check at room temperature.

The magnitude of the variation in the coefficient of linear expansion can be expressed by using the coefficient of variation of the coefficient of linear expansion of the measurement sample obtained from different parts of the site. The coefficient of variation referred to here is the same as that described in the section of the coefficient of variation of tensile breaking strength described above.

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%, even 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 ease of manufacture.

The number of samples (n) when calculating the coefficient of variation of the linear expansion coefficient is preferably 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 made of a highly heat-resistant organic polymer other than cellulose (for example, fibrillated fibers or fine fibers of aramid fibers); a compatibilizer; Plastics; Polysaccharides such as starches and alginic acid; Natural proteins such as gelatin, nikawa and casein; Inorganic compounds such as zeolites, ceramics, talc, silica, metal oxides and metal powders; Colorants; Fragrances; Pigments; Flow adjustment Agents; leveling agents; conductive agents; antistatic agents; ultraviolet absorbers; ultraviolet dispersants; deodorants and other additives may be blended. The content ratio of any additive in the resin composition is appropriately selected as long as the desired effect of the present invention is not impaired.

The resin composition of the present embodiment can be provided in various shapes. Specific examples thereof include a resin pellet shape, a sheet shape, a fibrous shape, a plate shape, a rod shape, and the like, but the resin pellet shape is more preferable from the viewpoint of ease of post-processing and ease of transportation. Preferred pellet shapes at this time include a round shape, an elliptical shape, a cylindrical shape, and the like, which differ depending on the cutting method at the time of extrusion processing. Pellets cut by a cutting method called underwater cut often have a round shape, and pellets cut by a cutting method called hot cut often have a round or oval shape, which is called a strand cut. 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 the pellet diameter. Further, in the case of columnar pellets, the preferable diameter is 1 mm or more and 3 mm or less, and the preferable length is 2 mm or more and 10 mm or less. The above diameter and length are preferably not more than the lower limit from the viewpoint of operational stability during extrusion, and preferably not more than the upper limit from the viewpoint of biting into the molding machine in post-processing.

The resin composition of the present embodiment can be used as various resin molded products. The method for producing the resin molded product is not particularly limited, and any manufacturing 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, and specific examples thereof include the following methods.

A method in which a mixture of polyamide, elastomer, and cellulose is melt-kneaded using a single-screw or twin-screw extruder, extruded into strands, cooled and solidified in a water bath to obtain a pellet-shaped molded product, single-screw or twin-screw extrusion. Similarly, a method of melt-kneading using a machine and extruding into a rod or cylinder to obtain an extruded molded product, melt-kneading using a single-screw or twin-screw extruder, and extruding from a T-die into a sheet or film. Examples thereof include a method for obtaining a molded product of.

The resin composition of the present embodiment has high mechanical properties and low linear expansion, and not only has high fluidity suitable for large parts, but also has substantially no partial strength defects. Therefore, it can be suitably used for various large-sized component applications.

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

[Raw materials and evaluation method]
The raw materials used and the evaluation method will be described below.

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

≪Elastomer≫
Elastomer with acidic functional group Tough Tech M1943 (Asahi Kasei Corporation) (hereinafter referred to simply as MSEBS)
Maleic anhydride-modified styrene-ethylenebutylene-styrene block copolymer bonded 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 (DuPont) (hereinafter simply referred to as MEOR)
Maleic anhydride-modified ethylene-octene copolymer MFR (190 ° C., 2.16 kgf) = 1.2 g / 10 minutes 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 tough tech H1052 without acidic functional group (Asahi Kasei Corporation) (hereinafter referred to simply as SEBS)
Styrene-Ethylene Butylene-Styrene Block Copolymer Bonded Styrene Content = 20% by Mass
MFR (230 ° C, 2.16 kgf) = 13 g / 10 minutes Engage 8180 (The Dow Chemical Company) (hereinafter referred to simply as EOR)
Ethylene-octene copolymer MFR (190 ° C, 2.16 kgf) = 0.5 g / 10 minutes Octene content = 28% by mass
Melting point = 49 ° C (DSC method: heating rate 10 ° C / min)

≪Cellulose≫
[Preparation Example 1] Cellulose nanocrystal (hereinafter referred to as CNC)
Commercially available DP pulp (average degree of polymerization 1600) was cut and hydrolyzed in a 10 mass% hydrochloric acid aqueous solution at 105 ° C. for 30 minutes. The obtained acid-insoluble residue was filtered, washed, and adjusted in pH to prepare a crystalline cellulose dispersion having a solid content concentration of 14% by mass and a pH of 6.5. This crystalline cellulose dispersion was spray-dried to obtain a dried product of crystalline cellulose. Next, the supply amount was set to 10 kg / hr, and the dried product obtained above was supplied to an airflow type crusher (STJ-400 type, manufactured by Seishin Enterprise Co., Ltd.) and pulverized to obtain CNC as a crystalline cellulose fine 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 PEG20000) to 100 parts by mass of CNC to the obtained aqueous dispersion of CNC, a revolving / rotating stirrer (V-mini300 manufactured by EME). ) Was vacuum dried at about 40 ° C. to obtain a CNC powder.

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

To the obtained aqueous dispersion of CNF, 5 parts by mass of PEG20000 was added to 100 parts by mass of CNF, and then vacuum dried at about 40 ° C. using a revolving / rotating stirrer (V-mini300 manufactured by EME). , CNF powder was obtained.

[Preparation Example 3] Hydrophobicized CNF (hereinafter referred to as hydrophobicized CNF)
(Defibration process)
Using a linter pulp raw material, the mixture was stirred in 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) with a hose pump and circulated for 120 minutes using only DMSO to obtain a defibrated slurry.

(Defibration / acetylation process)
Then, 11 parts by mass of vinyl acetate and 1.63 parts by mass of sodium hydrogen carbonate were added to 100 parts by mass of the defibrated slurry and then circulated for 60 minutes to obtain a hydrophobic 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). Further, during the circulation operation, the slurry temperature was controlled to 40 ° C. by a chiller in order to absorb heat generated by friction.

To the obtained hydrophobic CNF slurry, 192 parts by mass of pure water was added to 100 parts by mass of the defibrated 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 in the same amount of pure water was repeated a total of 5 times.

When the characteristics 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 PEG20000 to 100 parts by mass of the hydrophobicized CNF to the aqueous dispersion (solid content: 10% by mass) of the obtained hydrophobicized CNF, a revolving / rotating stirrer (V-made by EME). The hydrophobized CNF powder was obtained by vacuum drying at about 40 ° C. using mini300).

[Preparation Example 4] Hydrophobicized Cellulose Fiber (hereinafter referred to as Hydrophobicized CellF)
(Defibration process)
The same procedure was carried out except that the high-pressure homogenizer of Preparation Example 2 was treated twice to obtain a defibrated slurry. The obtained defibration slurry was carried out in the same manner as in the defibration / acetylation step of Preparation Example 3.
When the characteristics 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 PEG20000 to 100 parts by mass of the hydrophobicized CNF to the aqueous dispersion (solid content ratio: 10% by mass) of the obtained hydrophobicized CMF, a revolving / rotating stirrer (V-made by EME). The hydrophobized CNF powder was obtained by vacuum drying at about 40 ° C. using mini300).

≪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, Hydrophobicized CNF Length, Diameter, L / D>
Make cellulose into a pure water suspension at a concentration of 1% by mass, and use a high-shear homogenizer (manufactured by Nippon Seiki Co., Ltd., trade name "Excel Auto Homogenizer ED-7", treatment conditions: rotation speed 15,000 rpm x 5 minutes). The dispersed aqueous dispersion is diluted with pure water to 0.1 to 0.5% by mass, cast on mica, and air-dried, which is obtained when measured by an atomic force microscope (AFM). The ratio (L / D) when the length (L) and the diameter (D) of the particle image were taken was determined, and calculated as the average value of 100 to 150 particles.

<Average diameter of CNF, CNC, hydrophobized CNF>
In a planetary mixer (manufactured by Shinagawa Machinery Works Co., Ltd., trade name "5DM-03-R", stirring blade is hook type) with a cellulose component of 40% by mass as a solid content, at 126 rpm for 30 minutes at room temperature and normal pressure. Kneaded. Next, a pure water suspension was prepared with a solid content of 0.5% by mass, and a high shear homogenizer (manufactured by Nippon Seiki Co., Ltd., trade name "Excel Auto Homogenizer ED-7", processing conditions: rotation speed 15,000 rpm Disperse in (× 5 minutes) and centrifuge (manufactured by Kubota Shoji Co., Ltd., trade name "6800 type centrifuge", rotor type RA-400 type, treatment conditions: Centrifugal force 39,200 m ² / s for 10 minutes. Was collected, and the supernatant was ^{centrifuged at 116000 m 2} / s for 45 minutes.) Volume obtained by laser diffraction / scattering particle size distribution meter (manufactured by HORIBA, Ltd., trade name "LA-910", ultrasonic treatment for 1 minute, refractive index 1.20) using the supernatant after centrifugation. The integrated 50% particle size (volume average particle size) in the frequency particle size distribution was measured, and this value was taken as the average size.

<CMF diameter, L / D>
Dilute the CMF slurry to make a low-concentration aqueous dispersion of about 0.1% by mass, and observe and photograph the aqueous dispersion that has been dispersed for 20 minutes with a despamill (manufactured by Asada Iron Works Co., Ltd.) as it is with an optical microscope. Then, the diameter and L / D (the average of 200 numbers each) 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 no particular change occurred in both the examples and comparative examples carried out this time, it was judged that the polyamide formed a continuous phase.

<Cellulose present phase>
In order to confirm the presence position 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 polyamide phase was dyed for confirmation of cellulose in the polyamide phase, and the elastomer phase was dyed for confirmation of cellulose in the elastomer phase with a known dyeing agent, respectively, so that cellulose could be clearly confirmed.

For those whose cellulose position could be clearly determined by the first means, the second means was not performed, and "---" was written in the column of Examples.

For samples whose presence of cellulose could not be clearly determined by electron microscopic observation, a solvent elution method was carried out as a second means. Specifically, the obtained composition is sliced to a thickness of 1 μm using an ultramicrotome to obtain a film-like sample, and then immersed in chloroform to elute the elastomer phase, and the eluate is concentrated and ultracentrifuged. After separation and separation of cellulose, the cellulose was washed with chloroform and ultracentrifugation was repeated 3 times. The final remaining cellulose was dried to determine the amount of cellulose present in the elastomer phase. The obtained amount was subtracted from the charged amount and divided by the charged cellulose amount as a percentage, which was used as the polyamide phase ratio of cellulose. At this time, in the case of the sample in which the conductive filler coexisted, the sample before the addition of the conductive filler was verified.

<Number average particle size of elastomer-dispersed particles and volume ratio of dispersed particles with a particle size of 1 μm or more>
Using an electron micrograph when confirming the presence position of cellulose, the number average value of the diameter (that is, the dispersed particle diameter) and the volume of the dispersed particles having a particle diameter of 1 μm or more for 500 dispersed particles of the elastomer dispersed phase. The ratio was calculated.

≪Density≫
An injection molding machine was used to mold ISO 294-3 compliant multipurpose test pieces. The molding conditions were carried out in accordance with JIS K6920-2.
A measurement sample was cut out from the obtained test piece, and the density was measured according to ISO1183.

≪Coefficient of thermal expansion (coefficient of linear expansion)≫
A cubic sample having a length of 4 mm, a width of 4 mm, and a length of 4 mm is cut out from the central part of the multipurpose test piece with a precision cut-and-sew, and the resin at the time of molding is formed in the measurement temperature range of -10 to 120 ° C. in accordance with ISO11359-2. The expansion coefficient with respect to the flow direction (MD direction) was measured, and the expansion coefficient (hereinafter referred to as _{CTE MD) between 20 ° C. and 100 ° C. was calculated.} At this time, prior to the measurement, annealing was performed by allowing the mixture to stand for 5 hours in an environment of 120 ° C.

≪Anisotropy≫
Except that the measurement direction of the coefficient of thermal expansion was changed to the direction perpendicular to the flow direction of the resin at the time of molding, the measurement was carried out in the same manner as the measurement of the coefficient of thermal expansion (linear expansion coefficient). (Called CTE _TD ) was calculated. From the obtained results, it was evaluated as anisotropy by the following formula.
Anisotropy (%) = CTE _MD / CTE _TD x 100

≪Toughness strain during tensile failure≫
A tensile test was carried out in accordance with ISO527 using a multipurpose test piece, and five points of strain data at the time of tensile fracture were arithmetically averaged and used as an index of toughness.

<< Coefficient of variation of linear expansion coefficient >>
Using the pellets obtained in the examples, the cylinder temperature of an injection molding machine having a maximum mold clamping pressure of 4000 tons is set to 250 ° C., and a predetermined mold capable of molding a fender having the shape shown in the schematic view of FIG. (Cavity volume: Approximately 1400 cm ³ , Average thickness: 2 mm, Projected area: Approximately 7000 cm ² , Number of gates: 5-point gate, Hot runner: In FIG. 4, a runner is used to clarify the runner position of the molded product. The relative position 1 of (hot runner) was shown in the figure), the mold temperature was set to 60 ° C., and the fender was molded.

Using the obtained fender, 10 small flat plate test pieces having a length of about 10 mm, a width of about 10 mm, and a thickness of 2 mm were collected by cutting out into a square of about 10 mm from the positions (1) to (10) in FIG. .. Note that (1) to (3) are near the molded body gate, (4) to (7) are flow end portions of the molded body, and (8) to (10) are central portions of the molded body.

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

Prior to the measurement, an annealing was carried out by allowing the mixture to stand in an environment of 120 ° C. for 5 hours to obtain a sample for measurement. The obtained sample was measured in the measurement temperature range of -10 ° C to + 80 ° C in accordance with ISO11359-2, and the expansion coefficient between 0 ° C and 60 ° C was calculated to obtain a total of 10 measurement results. rice field. Based on these 10 measurement data, the coefficient of variation (CV) was calculated based on the following equation.
CV = (σ / μ) × 100
Here, σ represents the standard deviation and μ represents the arithmetic mean of the tensile breaking strength.

≪Conductivity≫
In Examples and Comparative Examples in which a conductive material was added, the volume resistivity was measured as conductivity.
A multipurpose test piece was formed from the obtained resin composition pellets having a volume resistivity. This test piece was scratched in advance with a cutter knife, soaked in dry ice / methanol at -75 to -70 ° C for 1 hour, then taken out and immediately broken off to break a uniform cross-sectional area of 10 x 4 mm at both ends. 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 resistivity between both fracture surfaces was measured at an applied voltage of 250 V using a digital ultra-high resistance / micro ammeter [R8340A: manufactured by Advantest]. , The volume resistivity was calculated. The measurement was performed on 5 different test pieces, and the added average was taken as the volume resistivity.

<Extruder design-1>
L / D with 13 cylinder blocks cools cylinder 1 of 52 twin-screw extruder (TEM SX series extruder manufactured by Toshiba Machine Co., Ltd.) with water, cylinders 2 to 4 at 150 ° C, and cylinders 5 to die. Was set to 250 ° C. A vent port for vacuum suction was installed in the cylinder 12 so that volatile components and coexisting air could be removed.

As for the screw configuration, cylinders 1 and 2 are used as transfer screws, and three clockwise kneading discs (feed type kneading discs: hereinafter, may be simply referred to as RKD) are arranged in cylinders 3 to form a premixing zone. , Cylinder 4 is used as a transport screw, and one RKB and two neutral kneading discs (non-conveyance type kneading disc: hereinafter, may be simply referred to as NKD) from cylinders 5 to 6 and one subsequently. The counterclockwise screw was arranged to form a melt-kneading zone. Cylinders 7 to 9 which are side feed zones are used as transfer screws, and two RKBs, three NKBs, and a counterclockwise screw are arranged in the cylinder 10 to form a kneading zone. The cylinders 11 to 13 were used as a transport screw and used as a volatilization zone. Further, a die having two holes having a diameter of 3 mm was attached to the die.

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

<Extruder Design-3>
Of the screws arranged on the cylinders 5 to 6, one counterclockwise screw was changed to two seal rings having a clearance of 0.2 mm, which was the same as that of the extruder design-2.

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

[Preparation Example 5]
Using the extruder of Extruder Design-1, 70 parts by mass of PA6-1 and 30 parts by mass of hydrophobized CNF are quantitatively fed from the upstream supply port by different loss-in weight type feeders, and vacuum suction is performed. During this process, the screw rotation speed was melt-kneaded at 300 rpm to obtain a master batch pellet. This masterbatch pellet is referred to as PA6-1 / hydrophobicized CNF. In addition, this masterbatch contains a small amount of 20000 added at the time of hydrophobized CNF drying.

[Preparation Example 6]
Using the extruder of Extruder Design-1 with the temperature setting of all cylinders and dies set to 150 ° C, 70 parts by mass of MEOR and 30 parts by mass of hydrophobic CNF from the upstream supply port are different loss-in weight types. A fixed amount was fed by a feeder, and while suction was performed under reduced pressure, the screw rotation speed was melt-kneaded at 300 rpm to obtain a master batch pellet. This masterbatch pellet is referred to as MEOR / hydrophobized CNF. In addition, this masterbatch also contains a small amount of 20000 added at the time of hydrophobizing CNF drying.

[Examples 1 and 2, Comparative Examples 1 and 2]
Using the extruder of Extruder Design-1, the mixture was mixed at the ratio shown in Table 1, melt-kneaded at a screw rotation speed of 300 rpm to obtain pellets, and then various evaluations were carried out. The results are shown in Table 1.
In addition, the column described by the mass part of the table is the preparation prescription, the column of mass% in the middle row shows the composition, and the column in the lower row shows the physical properties.

From the results shown in the table, although the compositions are almost the same, Comparative Examples 1 and 2 in which more than 50% by mass of cellulose was not present in the polyamide phase had a high coefficient of linear expansion and a large strain during tensile fracture. It can be seen that the coefficient of linear expansion decreases and the variation in b depending on the site of the coefficient of linear expansion also increases. It is considered that this is because cellulose is mainly present in the elastomer phase, so that the linear expansion reducing effect cannot be sufficiently exhibited, and the impact developing effect of the elastomer is also suppressed.

[Examples 3 to 4, Comparative Examples 3 to 5]
Using the extruder of Extruder Design-1, the mixture was mixed at the ratio shown in Table 2, melt-kneaded at a screw rotation speed of 300 rpm to obtain pellets, and then various evaluations were carried out. The results are shown in Table 2.

From the results shown in Table 2, it can be seen that the presence position of cellulose changes and the characteristics also change significantly depending on the amount of the elastomer having an acidic functional group in the rubber. The reason for the presence of cellulose in a small amount of the elastomer phase, despite not using a master batch, is that the elastomer melts at a much lower temperature than polyamide and is first kneaded with cellulose. It is considered that the affinity with cellulose is increased by the acid denaturation of the elastomer.

[Examples 5 to 12]
Using the extruder of Extruder Design-1, the mixture was mixed at the ratio shown in Table 3, melt-kneaded at a screw rotation speed of 300 rpm to obtain pellets, and then various evaluations were carried out. The results are shown in Table 3.
In addition, in order to help understanding, Example 3 is reprinted.

[Comparative Examples 6 and 7]
Using the extruder of Extruder Design-2, the mixture was mixed at the ratio shown in Table 4, melt-kneaded at a screw rotation speed of 300 rpm to obtain pellets, and then various evaluations were carried out. The results are shown in Table 4.

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

From the results shown in Table 4, it can be seen that when a general inorganic filler is used instead of cellulose, not only the density increases and the weight reduction effect diminishes, but also problems such as anisotropy appear. Due to the large anisotropy, the molded fender molded body had a large warp.

[Examples 13 to 17, Comparative Example 8]
Extruder Design-1 extruders for Examples 13 and 14, Extruder Design-2 extruders for Examples 15 and 8 and Extruder Design-for Examples 16 and 17. Using the extruder of No. 3, melt-kneading was performed at a rotation speed of 300 rpm to obtain pellets, and then various evaluations were carried out. The results are shown in Table 5.
In addition, in order to help understanding the difference depending on the type of filler, Example 3 is reprinted.

The final composition of Examples 3 and 15 to 17 and Comparative Example 8 is the same. However. In comparison between Examples 3 and 15 and Comparative Example 8, it can be seen that the location of cellulose is significantly changed and the characteristics are also significantly different depending on the position of addition of cellulose and the position of addition of the elastomer component. It is considered that the location is chlorinated due to the difference in the state of the polymer at the time of kneading the cellulose and the polymer.

Further, although the extruder design is different between Example 3 and Examples 16 and 17, the dispersed particle size of the elastomer is very fine in Examples 16 and 17 as compared with Example 3. Moreover, it can be seen that the particle size uniformity is also improved. From this effect, 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 the extruder of Extruder Design-2, the mixture was mixed at the ratio shown in Table 6, melt-kneaded at a screw rotation speed of 300 rpm to obtain pellets, and then various evaluations were carried out. The results are shown in Table 6. Since Examples 18 and 19 have compositions in which conductive carbon black is added to Examples 9 and 10, respectively, Examples 9 and 10 are also reprinted.

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

The resin composition of the present invention simultaneously achieves contradictory properties such as low specific density, low coefficient of thermal expansion, low anisotropy, and high toughness, and has sufficient physical stability to withstand practical use and is stable. It can be suitably used in the field of automobile exterior material applications, which are large parts that require performance.

Claims (15)

A resin composition containing polyamide, an elastomer, and cellulose.
The cellulose contains at least fibrous cellulose and contains
The polyamide and the elastomer are phase-separated.
A resin composition in which more than 50% by mass 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. One or more kinds of polyamides 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 or 2. 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 with respect to 100 parts by mass of the polyamide. The elastomer is selected from the group consisting of ethylene-α-olefin copolymers, block copolymers of aromatic vinyl compounds and conjugated diene compounds, and block copolymers of aromatic vinyl compounds and conjugated diene compounds. The resin composition according to any one of claims 1 to 5, which is one or more of the above-mentioned resin compositions. The resin composition according to any one of claims 1 to 6, wherein at least a part of the elastomer has an acidic functional group. The resin composition according to claim 7, wherein the elastomer is an acid anhydride-modified elastomer. The resin composition according to claim 7 or 8, wherein the elastomer is a mixture of an elastomer having an acidic functional group and an elastomer having no acidic functional group. The elastomer is present as dispersed particles in the polyamide continuous phase and
The resin composition according to any one of claims 1 to 9, wherein the dispersed particles have a number average particle diameter of 3 μm or less. The elastomer is present as dispersed particles in the polyamide continuous phase and
The resin composition according to any one of claims 1 to 10, wherein the dispersed particles have a volume ratio of 30% by volume or less of particles having a particle diameter of 1 μm or more. The resin composition according to any one of claims 1 to 11, wherein the amount of cellulose is 0.1 to 30% by mass with respect to 100% by mass of the resin composition. The resin composition according to any one of claims 1 to 12, wherein the fibrous cellulose is hydrophobic cellulose. The resin composition according to any one of claims 1 to 13, wherein the coefficient of thermal expansion at 20 ° C. to 100 ° C. is 50 ppm / k or less. A molded product made of the resin composition according to any one of claims 1 to 14.

Images