Fine cellulose-containing resin composition

Abstract

To provide a resin composition which has good boundary adhesion to a resin, uses a CNF filler that is reduced in problems in reduction in environmental load and physical properties by a chemical modification process, and can impart a resin composite excellent in abrasion resistance and durability, and a resin composite that is a molded body of the same.SOLUTION: A resin composition contains partially hydrolyzed fine cellulose (A) and a thermoplastic resin (B). A resin composition contains partially hydrolyzed fine cellulose (A), a thermoplastic resin (B) and hemicellulose (C). In a preferred embodiment, the partially hydrolyzed fine cellulose (A) is a fine cellulose fiber having a fiber length / fiber diameter aspect ratio of 30 or more.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a resin composition containing fine cellulose having a partially hydrolyzed structure, and in particular to a resin composition that can give a molded article having good sliding properties. [Background technology]

[0002] Thermoplastic resins are lightweight and have excellent processability, making them widely used in a wide range of applications, including automotive components, electrical and electronic components, office equipment housings, precision components, etc. However, resins alone often lack sufficient mechanical properties, sliding properties, thermal stability, dimensional stability, etc., so composites of resins and various inorganic materials are generally used.

[0003] Resin compositions in which thermoplastic resins are reinforced with reinforcing materials such as glass fibers, carbon fibers, talc, clay, and other inorganic fillers have a high specific gravity, and therefore have the problem of resulting resin molded articles being heavy.

[0004] Therefore, in recent years, cellulose, which has a low environmental impact, has come to be used as a new reinforcing material for resins.

[0005] Cellulose is known to have high elastic modulus comparable to that of aramid fiber and a linear expansion coefficient lower than that of glass fiber. It also has a true density of 1.56 g / cm 3 and is as low as glass (density 2.4-2.6g / cm3) which is commonly used as a reinforcing material for thermoplastic resins. 3 ) and talc (density 2.7g / cm 3 ) is an overwhelmingly lighter material than

[0006] Cellulose comes from a wide variety of sources, including trees, hemp, cotton, kenaf, and cassava. Bacterial cellulose, such as that used in nata de coco, is also known. These natural resources are abundant on Earth, and in order to make effective use of them, technology that utilizes cellulose as a filler in resins is attracting attention.

[0007] To fully utilize the properties of cellulose, it is necessary to create a fine, uniform dispersion state in a thermoplastic resin. Cellulose obtained from natural resources is physically and / or chemically bound to hemicellulose and lignin to form strong cell walls. Therefore, to use it as a fine filler, a process is required to disintegrate the cellulose fibers and extract fine cellulose fibers. Cellulose fibers disintegrated to nanometer sizes (less than 1 micron) are called CNFs (cellulose nanofibers). They are obtained from pulp, etc., obtained by pretreatments such as cooking, screening, and bleaching natural plant resources. They are obtained by mechanical disintegration methods such as high-pressure homogenization, microfluidization, underwater head-on collision, ball milling, or disc milling, or by low-energy disintegration methods using chemical processes such as TEMPO oxidation and sulfuric acid esterification. They are known to form a highly dispersed state and network in water at a level referred to as fine nanodispersion.

[0008] Commonly used thermoplastic resins and cellulose often have poor affinity due to differences in surface free energy, and the interfacial adhesion between CNF and thermoplastic resin is low, so their properties often cannot be fully demonstrated. In response to this, a method is known in which chemically modified cellulose nanofibers are used to improve the surface condition of cellulose (Patent Document 1). [Prior art documents] [Patent documents]

[0009] [Patent Document 1] Japanese Patent Application Laid-Open No. 2017-171698

[0010] However, chemical modification of cellulose nanofibers dispersed in water requires solvent substitution treatment, which not only increases the cost of cellulose nanofiber production but also the amount of by-product waste and energy consumption, thereby diminishing the environmentally friendly advantage of cellulose.

[0011] Another known method involves adsorbing counter-ionic additives onto ionized modified cellulose nanofibers in water to obtain modified cellulose nanofibers. However, because the heat resistance of ionized modified cellulose is reduced, the cellulose nanofibers undergo thermal decomposition during the process of being kneaded with resin at high temperatures, preventing them from exerting their intended reinforcing effect, which can result in unstable quality and equipment problems. Summary of the Invention [Problem to be solved by the invention]

[0012] The present invention aims to solve the problems of the conventional technology described above, and to provide a resin composition and a resin composite molded from the resin composition, which uses a CNF filler that has good interfacial adhesion with resin and reduces the problems of environmental impact and deterioration of physical properties due to the chemical modification process, and can give a resin composite with excellent abrasion resistance and durability. [Means for solving the problem]

[0013] As a result of intensive research into solving the above-mentioned problems, the present inventors have found that a resin composition containing partially hydrolyzed cellulose and further containing a specific compound can solve the above-mentioned problems, and have thus completed the present invention. That is, the present invention includes the following aspects.

[0014] [1] A resin composition comprising partially hydrolyzed fine cellulose (A) and a thermoplastic resin (B). [2] The resin composition according to aspect 1, further comprising hemicellulose (C). [3] The resin composition according to the above-mentioned aspect 1 or 2, wherein the partially hydrolyzed fine cellulose (A) is fine cellulose fiber having an aspect ratio of fiber length / fiber diameter of 30 or more. [4] The partially hydrolyzed fine cellulose (A) has a peak top molecular weight corresponding to a degree of polymerization of 450 or more, The resin composition according to any one of the above aspects 1 to 3, wherein in the partially hydrolyzed fine cellulose (A), when the amount of low molecular weight components having a molecular weight equal to or less than the peak top molecular weight is S1 and the amount of high molecular weight components having a molecular weight exceeding the peak top molecular weight is S2, S1 / S2 is greater than 1.00. [5] The resin composition according to aspect 4, wherein the S1 / S2 ratio is greater than 1.00 and equal to or less than 3.00. [6] The resin composition according to any one of the above aspects 1 to 5, wherein the partially hydrolyzed fine cellulose (A) has an average fiber diameter of 4 to 3,000 nm. [7] The resin composition according to any one of the above aspects 1 to 6, wherein the mass ratio (A) / (B) of the partially hydrolyzed fine cellulose (A) to the thermoplastic resin (B) is 0.01 to 1. [8] The resin composition according to any one of the above aspects 1 to 7, wherein the resin composition contains hemicellulose (C), and the mass ratio (C) / (A) of hemicellulose (C) to partially hydrolyzed fine cellulose (A) is 0.001 to 0.2. [9] The resin composition according to any one of the above aspects 1 to 8, wherein the resin composition contains hemicellulose (C) and lignin (D), and the mass ratio (D) / (C) of lignin (D) / hemicellulose (C) is 0.001 to 10.

[10] The resin composition according to any one of the above aspects 1 to 9, wherein the thermoplastic resin (B) is a polyamide resin.

[11] A method for producing the resin composition according to any one of the above aspects 1 to 10, Heating fine cellulose and / or plant fiber in a water-containing atmosphere with an oxygen concentration of 18% by volume or less to obtain a blending component containing partially hydrolyzed fine cellulose (A); combining the blending components with the thermoplastic resin (B); A method comprising:

[12] A sliding member, which is a molded article of the resin composition according to any one of the above embodiments 1 to 10. [Effects of the Invention]

[0015] According to the present invention, a resin composition and a molded resin composite thereof can be provided, which use a CNF filler that has good interfacial adhesion with resin and reduces the environmental impact and deterioration of physical properties caused by the chemical modification process, and can give a resin composite with excellent abrasion resistance and durability. DETAILED DESCRIPTION OF THE INVENTION

[0016] Hereinafter, an embodiment of the present invention (hereinafter referred to as "the present embodiment") will be described in detail. Note that the present invention is not limited to the following embodiment, and various modifications can be made within the scope of the gist of the present invention.

[0017] <Resin composition> In one embodiment, the resin composition comprises partially hydrolyzed fine cellulose (A) and a thermoplastic resin (B). In one embodiment, the resin composition comprises partially hydrolyzed fine cellulose (A), a thermoplastic resin (B), and a hemicellulose (C).

[0018] [(A) Partially hydrolyzed fine cellulose] The partially hydrolyzed fine cellulose (A) may be derived from a variety of sources, including natural cellulose and regenerated cellulose.

[0019] Examples of natural cellulose that can be used include wood pulp obtained from wood species (broadleaf or coniferous trees), non-wood pulp obtained from non-wood species (bamboo, hemp-based fibers, bagasse, kenaf, linter, etc.), and purified pulp (purified linter) thereof. Examples of non-wood pulp that can be used include cotton-derived pulp, including cotton linter pulp, hemp-derived pulp, bagasse-derived pulp, kenaf-derived pulp, bamboo-derived pulp, straw-derived pulp, and banana-derived pulp. Cotton-derived pulp, hemp-derived pulp, bagasse-derived pulp, kenaf-derived pulp, bamboo-derived pulp, straw-derived pulp, and banana-derived pulp are preferably purified pulps obtained from raw materials such as cotton lint, cotton linter, hemp-based abaca (e.g., from Ecuador or the Philippines), sisal, bagasse, kenaf, bamboo, straw, and banana stalks, respectively, through a purification process such as delignification by cooking, a bleaching process, and the like. Cellulose derived from seaweed can also be used.

[0020] Regenerated cellulose is a substance obtained by dissolving or mercerizing natural cellulose and regenerating it. It is a β-1,4-linked glucan (glucose polymer) with a molecular arrangement that gives a crystal diffraction pattern (cellulose type II crystal) with peaks at diffraction angles corresponding to lattice spacings of 0.73 nm, 0.44 nm, and 0.40 nm when measured by particle beam diffraction. In the X-ray diffraction pattern, regenerated cellulose has one peak at 10°≦2θ<19° and two peaks at 19°≦2θ≦30° in the 2θ range of 0° to 30°. Examples of regenerated cellulose include rayon, cupra, and Tencel. Because regenerated cellulose can easily be produced into fibers with diameters exceeding 100 nm, regenerated cellulose is sometimes preferred from the perspective of dispersibility in resins. Cupra and Tencel, which have high molecular orientation along the fiber axis, are particularly preferred as raw materials for fine cellulose due to their ease of micronization. Furthermore, cut yarns of regenerated cellulose fibers and cut yarns of cellulose derivative fibers can also be used as raw materials. Furthermore, a mixture of natural cellulose and regenerated cellulose may be used as the raw material.

[0021] Cellulose fibers are generally known to contain regularly arranged crystalline structure portions and irregular amorphous structure portions. Typically, approximately 40 cellulose molecules form microfibrils with a width of approximately 4–5 nm through intermolecular hydrogen bonding, and multiple microfibrils gather to form bundles with a width of approximately 15 nm or more. These bundles are further defibrated to a state where they have a fiber diameter of tens to hundreds of nanometers, or even to the microfibril equivalent, and these are called cellulose nanofibers. Defibration of cellulose fibers increases their surface area, which increases the interface when composited with resin, thereby enhancing the mechanical properties (reinforcing effect). However, fine cellulose fibers that have been further defibrated to a microfibril-like state are prone to surface decomposition when heated during the composite formation process with resin. The average fiber diameter of the partially hydrolyzed fine cellulose (A) is preferably 4 nm or more, more preferably 15 nm or more, even more preferably 30 nm or more, and particularly preferably 50 nm or more. On the other hand, if the average fiber diameter of the partially hydrolyzed fine cellulose (A) is too large, the reinforcing effect will be reduced and the surface roughness of the resin composite will increase, which may result in poor design. Therefore, the average fiber diameter is preferably 3000 nm or less, more preferably 2000 nm or less, even more preferably 1500 nm or less, and particularly preferably 1000 nm or less. The average fiber diameter is a value measured by the method described in the section [Examples] of this disclosure.

[0022] The high elastic modulus and low linear expansion coefficient of cellulose are primarily due to its crystalline structure. Cellulose molecules in the crystalline structure are strongly hydrogen-bonded to each other, making them resistant to hydrolysis, whereas amorphous portions are easily hydrolyzed. Crystalline cellulose, which is obtained by cleaving amorphous cellulose molecules through acid hydrolysis and pulverizing them to a degree of polymerization of approximately 200–300, has a length / thickness aspect ratio of at most several tens, and is called cellulose nanowhiskers or cellulose nanocrystals. When pulverized to this size, when composited with resin, it is difficult for the cellulose nanocrystals to form a network through interactions between them in the resin, making it difficult to achieve reinforcing effects. Furthermore, such cellulose nanocrystals tend to have lower heat resistance than cellulose nanofibers with a higher aspect ratio. It is believed that the increased fiber surface area and / or the number of cellulose molecular ends increases the number of starting points for thermal decomposition.

[0023] In the partially hydrolyzed fine cellulose (A), at least a portion of the amorphous portion is hydrolyzed, and the cellulose is not decomposed to low-aspect-ratio cellulose nanocrystals. The aspect ratio of the length / thickness (fiber length / fiber diameter) of the partially hydrolyzed fine cellulose (A) is preferably 30 or more, more preferably 50 or more, and even more preferably 100 or more. By observing the fine cellulose used as a raw material or the fine cellulose recovered by dissolving and removing the resin from the resin composition with a scanning electron microscope (SEM), it is possible to confirm the presence of fine cellulose with an aspect ratio lower than the above-mentioned preferred range. It is preferable that the amount of fine cellulose cut to such a low aspect ratio in the resin composition is small, but it may be present within a range that can exhibit the desired reinforcing effect of the resin composition of the present invention. The aspect ratio is a value measured by the method described in the [Examples] section of this disclosure.

[0024] Although it is difficult to directly observe the local molecular structure of fine cellulose, the structure of the partially hydrolyzed fine cellulose of the present invention is considered to be as follows based on the results of macro-scale analysis. When cellulose is hydrolyzed, for example, by heating in the presence of water under neutral to weakly acidic conditions, at least a portion of the amorphous portion is hydrolyzed, while the crystalline structure is substantially maintained, to obtain partially hydrolyzed cellulose. Such partially hydrolyzed cellulose contains a large amount of cellulose with a low degree of polymerization when measured for molecular weight distribution, but contains almost no fine cellulose with a low aspect ratio when observed by morphological observation. In other words, in partially hydrolyzed cellulose, hydrolysis does not substantially occur in the inner layer of the microfibrils or microfibril bundles, and hydrolysis of the surface layer is limited to a certain extent, so that the cellulose can exist as fine cellulose with a high aspect ratio.

[0025] The partially hydrolyzed fine cellulose (A) can be analyzed by various methods commonly used for analyzing cellulose. The molecular weight distribution is preferably measured by gel permeation chromatography (GPC). The molecular weight distribution may be monomodal (having one peak), bimodal (having two peaks), or, in rare cases, three or more peaks. It is divided into low and high molecular weight regions based on the peak-top molecular weight (i.e., the molecular weight at the apex of the maximum peak). The peak-top molecular weight can be converted to the degree of polymerization by dividing it by the molecular weight of the anhydroglucose unit, which is the monomer structure of cellulose, 162. The degree of polymerization corresponding to the peak-top molecular weight is preferably 300 or more, more preferably 400 or more, even more preferably 450 or more, and particularly preferably 500 or more. When the peak-top molecular weight is equal to or greater than the above-mentioned degree of polymerization, excessive progress of partial hydrolysis is suppressed, the content of fine cellulose with a low aspect ratio equivalent to that of cellulose nanocrystals is low, and heat resistance is good. In molecular weight measurement, the amount of low molecular weight components (cumulative area intensity) having a molecular weight equal to or less than the peak top molecular weight is defined as S1, and the amount of high molecular weight components (cumulative area intensity) having a molecular weight exceeding the peak top molecular weight is defined as S2. The lower limit of the S1 / S2 ratio is preferably greater than 1.00, more preferably 1.05 or more, even more preferably 1.10 or more, even more preferably 1.15 or more, and particularly preferably 1.20 or more. When S1 / S2 is equal to or greater than these ratios, the partially hydrolyzed fine cellulose (A) provides the resin composite with excellent tensile strength, friction coefficient, and wear depth. The upper limit of the S1 / S2 ratio is preferably 3.00 or less, more preferably 2.50 or less, even more preferably 2.00 or less, even more preferably 1.90 or less, and particularly preferably 1.80 or less. When S1 / S2 is equal to or less than these ratios, thermal decomposition and performance degradation due to heating during kneading of the resin composite are suppressed.

[0026] The reason why partially hydrolyzed fine cellulose (A) exhibits superior effects to regular (i.e., non-partially hydrolyzed) fine cellulose is presumed to be as follows: Hydrolysis of the amorphous portion of cellulose generates a new reducing end (position 1 of the glucose unit) and a non-reducing end (position 4 of the glucose unit). Of these, the reducing end is in equilibrium with a hemiacetal group and an aldehyde group. When this aldehyde group reacts with functional groups such as amino groups, carboxy groups, and hydroxy groups present in the main chain and / or side chain and / or end of the thermoplastic resin, a covalent bond can be formed. As a result, the interfacial adhesion between the fine cellulose and the thermoplastic resin is strengthened.

[0027] [Hemicellulose (C) and lignin (D)] In one embodiment, the resin composition further contains hemicellulose (C) and / or lignin (D) (more typically, both hemicellulose (C) and lignin (D)). In plant-derived fine cellulose, polysaccharides collectively referred to as hemicellulose and aromatic compounds collectively referred to as lignin typically remain between microfibrils and between microfibril bundles. In the present invention, these components are preferably not completely removed during the production process of fine cellulose, but are allowed to remain at a content within a suitable range. Hemicellulose is a polysaccharide composed of sugars such as mannan and xylan, and forms hydrogen bonds with cellulose to bind microfibrils together. Furthermore, since the solubility parameter (SP value) of hemicellulose is more hydrophobic than that of cellulose, it is believed that hemicellulose has the effect of reducing the difference in SP value between thermoplastic resins and fine cellulose.

[0028] The amount of hemicellulose (C) in the resin composition of the present invention is preferably 0.001 or more, more preferably 0.005 or more, even more preferably 0.01 or more, even more preferably 0.02 or more, particularly preferably 0.03 or more, preferably 0.2 or less, more preferably 0.18 or less, and even more preferably 0.15 or less, in terms of the mass ratio (C) / (A) to the partially hydrolyzed fine cellulose (A). When the hemicellulose (C) is contained within the above-mentioned range, peeling of cellulose molecules with a low degree of polymerization from the surface layer when the fine cellulose is partially hydrolyzed is suppressed, and therefore the tensile strength, friction coefficient, and wear depth of the resin composite are good.

[0029] Lignin is a compound having an aromatic ring and is known to be covalently bonded to hemicellulose in plant cell walls. The amount of lignin (D) in the resin composition of the present invention, expressed as a mass ratio (D) / (C) relative to hemicellulose (C), is preferably 0.001 or more, more preferably 0.01 or more, even more preferably 0.1 or more, preferably 10 or less, more preferably 5 or less, and even more preferably 3 or less. Lignin is a more hydrophobic compound than hemicellulose and is thought to have the effect of further reducing the SP value difference between the thermoplastic resin and the fine cellulose. It is not preferable for the amounts of hemicellulose and lignin present to exceed the above-mentioned ranges, as this can cause a decrease in heat resistance and accompanying discoloration in the resin composite.

[0030] The amount of hemicellulose (C) can be adjusted to the desired amount by subjecting natural wood raw materials with a high hemicellulose content to a purification treatment, or when a raw material with a low hemicellulose content is used, by adding hemicellulose obtained by extraction treatment from another raw material. In this case, it does not matter if the structure of the terminals of the hemicellulose, etc., is partially different from that of the natural product due to the purification or extraction treatment. The amount of lignin (D) can be adjusted to the desired amount by subjecting natural wood raw materials with a high lignin content to a purification treatment, or by adding lignin obtained by extraction from another raw material when a raw material with a low lignin content is used. In this case, it does not matter if the structure of the lignin terminals, etc., is partially different from that of the natural product due to the purification or extraction treatment.

[0031] [Thermoplastic resin (B)] The thermoplastic resin (B) may be a crystalline resin having a melting point within the range of 100 to 350°C, or an amorphous resin having a glass transition temperature within the range of 100 to 250°C.

[0032] The melting point of a crystalline resin here refers to the peak-top temperature of the endothermic peak that appears when the temperature is increased from 23°C at a rate of 10°C / min using a differential scanning calorimeter (DSC). If two or more endothermic peaks appear, the melting point refers to the peak-top temperature of the highest endothermic peak. The enthalpy of this endothermic peak is preferably 10 J / g or higher, and more preferably 20 J / g or higher. Furthermore, when measuring, it is desirable to first heat the sample to a temperature condition of at least 20°C above the melting point to melt the resin, and then cool it to 23°C at a rate of 10°C / min.

[0033] The glass transition temperature of an amorphous resin refers to the peak-top temperature at which the storage modulus drops significantly and the loss modulus reaches its maximum when measured using a dynamic viscoelasticity measuring device at a heating rate of 2°C / min from 23°C and an applied frequency of 10 Hz. If two or more loss modulus peaks appear, the glass transition temperature refers to the peak-top temperature of the highest peak. To improve measurement accuracy, the measurement frequency should be at least once every 20 seconds. While there are no particular limitations on the method for preparing the measurement sample, it is preferable to use a cut-out piece of a hot-press molded product to eliminate the effects of molding distortion, and it is desirable to keep the size (width and thickness) of the cut-out piece as small as possible from the perspective of thermal conduction.

[0034] Examples of the thermoplastic resin (B) include polyamide-based resins, polyester-based resins, polyacetal-based resins, polycarbonate-based resins, polyacrylic-based resins, polyphenylene ether-based resins (including modified polyphenylene ethers obtained by blending or graft-polymerizing polyphenylene ethers with other resins), polyarylate-based resins, polysulfone-based resins, polyphenylene sulfide-based resins, polyethersulfone-based resins, polyketone-based resins, polyphenylene ether ketone-based resins, polyimide-based resins, polyamideimide-based resins, polyetherimide-based resins, polyurethane-based resins, polyolefin-based resins (for example, α-olefin (co)polymers), and various ionomers.

[0035] Specific preferred examples of the thermoplastic resin (B) include high-density polyethylene, low-density polyethylene (for example, linear low-density polyethylene), polypropylene, polymethylpentene, cyclic olefin resins, poly 1-butene, poly 1-pentene, polymethylpentene, ethylene / α-olefin copolymers, ethylene-butene copolymers, EPR (ethylene-propylene copolymer), modified ethylene-butene copolymers, EEA (ethylene-ethyl acrylate copolymer), modified EEA, modified EPR, modified EPDM (ethylene-propylene-diene terpolymer), ionomers, α-olefin copolymers, modified IR (isoprene rubber), modified SEBS (styrene-ethylene-butylene-styrene copolymer), halogenated isobutylene-paramethylstyrene copolymer, ethylene-acrylic acid modified products, ethylene-vinyl acetate copolymers and acid-modified products thereof, copolymers of (ethylene and / or propylene) and (unsaturated carboxylic acid and / or unsaturated carboxylic acid ester), copolymers of (ethylene and / or propylene) and (unsaturated carboxylic acid and / or unsaturated carboxylic acid ester) obtained by converting at least a portion of the carboxyl groups of these copolymers into metal salts. Polyolefins, block copolymers of conjugated dienes and vinyl aromatic hydrocarbons, hydrogenated block copolymers of conjugated dienes and vinyl aromatic hydrocarbons, copolymers of other conjugated dienes and non-conjugated olefins, natural rubber, various butadiene rubbers, various styrene-butadiene copolymer rubbers, isoprene rubber, butyl rubber, bromide copolymers of isobutylene and p-methylstyrene, halogenated butyl rubber, acrylonitrile butadiene rubber, chloroprene rubber, ethylene-propylene copolymer rubber, ethylene-propylene-diene copolymer rubber, styrene-isoprene Copolymer rubber, styrene-isoprene-butadiene copolymer rubber, isoprene-butadiene copolymer rubber, chlorosulfonated polyethylene, acrylic rubber, epichlorohydrin rubber, polysulfide rubber, silicone rubber, fluororubber, urethane rubber, polyvinyl chloride, polystyrene, acrylics such as polyacrylates and polymethacrylates, acrylonitrile copolymers with acrylonitrile as the main component, acrylonitrile-butadiene-styrene (ABS) resin, acrylonitrile-styrene (AS) resin, cellulose-based resins such as cellulose acetate,Examples include vinyl chloride / ethylene copolymers, vinyl chloride / vinyl acetate copolymers, ethylene / vinyl acetate copolymers, and saponified ethylene / vinyl acetate copolymers.

[0036] These may be used alone or in combination of two or more. When two or more types are used in combination, they may be used as a polymer alloy. In addition, the above-mentioned thermoplastic resins may be modified with at least one compound selected from unsaturated carboxylic acids, their acid anhydrides, and their derivatives.

[0037] Among these, from the viewpoints of heat resistance, moldability, designability, and mechanical properties, polyolefin resins, polyamide resins, polyester resins, polyacetal resins, polyacrylic resins, polyphenylene ether resins, polyphenylene sulfide resins, and mixtures of two or more thereof are listed, but are not limited to these. Among these, polyolefin resins, polyamide resins, polyester resins, polyacetal resins, etc. are more preferred resins from the viewpoints of handleability and cost.

[0038] Polyolefin resins are polymers obtained by polymerizing monomer units containing olefins (e.g., α-olefins). Specific examples of polyolefin resins include, but are not limited to, ethylene (co)polymers such as low-density polyethylene (e.g., linear low-density polyethylene), high-density polyethylene, ultra-low-density polyethylene, and ultra-high-molecular-weight polyethylene; polypropylene (co)polymers such as polypropylene, ethylene-propylene copolymer, and ethylene-propylene-diene copolymer; and copolymers of α-olefins and other monomer units such as ethylene-acrylic acid copolymer, ethylene-methyl methacrylate copolymer, and ethylene-glycidyl methacrylate copolymer.

[0039] The most preferred polyolefin resin here is polypropylene. In particular, polypropylene having a melt mass-flow rate (MFR) of 3 g / 10 min or more and 30 g / 10 min or less, measured at 230°C under a load of 21.2 N in accordance with ISO 1133, is preferred. The lower limit of the MFR is more preferably 5 g / 10 min, even more preferably 6 g / 10 min, and most preferably 8 g / 10 min. The upper limit is more preferably 25 g / 10 min, even more preferably 20 g / 10 min, and most preferably 18 g / 10 min. From the viewpoint of improving the toughness of the composition, it is desirable for the MFR not to exceed the upper limit, and from the viewpoint of the flowability of the composition, it is desirable for the MFR not to exceed the lower limit.

[0040] In addition, acid-modified polyolefin resins can also be suitably used to enhance affinity with cellulose. The acid can be appropriately selected from polycarboxylic acids such as maleic acid, fumaric acid, succinic acid, phthalic acid and their anhydrides, and citric acid. Among these, maleic acid or its anhydride is preferred because it is easy to increase the modification rate. There are no particular restrictions on the modification method, but a common method is to heat the resin to above its melting point in the presence or absence of a peroxide and melt-knead it. All of the above-mentioned polyolefin resins can be used as acid-modified polyolefin resins, but polypropylene is particularly suitable.

[0041] Although the acid-modified polyolefin resin may be used alone, it is more preferable to use it in combination with an unmodified polyolefin resin to adjust the modification rate as a composition. For example, when a mixture of unmodified polypropylene and acid-modified polypropylene is used, the ratio of the acid-modified polypropylene to the total propylene is preferably 0.5% by mass to 50% by mass. A more preferred lower limit is 1% by mass, even more preferably 2% by mass, even more preferably 3% by mass, particularly preferably 4% by mass, and most preferably 5% by mass. A more preferred upper limit is 45% by mass, even more preferably 40% by mass, even more preferably 35% by mass, particularly preferably 30% by mass, and most preferably 20% by mass. To maintain the interfacial strength with cellulose, a content equal to or greater than the lower limit is preferable, and to maintain the ductility of the resin, a content equal to or less than the upper limit is preferable.

[0042] The melt mass-flow rate (MFR) of the acid-modified polypropylene, measured in accordance with ISO 1133 at 230°C under a load of 21.2 N, is preferably 50 g / 10 min or more to enhance affinity with the cellulose interface. A more preferred lower limit is 100 g / 10 min, even more preferably 150 g / 10 min, and most preferably 200 g / 10 min. There is no particular upper limit, but in order to maintain mechanical strength, it is 500 g / 10 min. By keeping the MFR within this range, the advantage of being more likely to be present at the interface between cellulose and resin can be enjoyed.

[0043] Preferred polyamide resins as the thermoplastic resin are, but are not particularly limited to, polyamide 6, polyamide 11, polyamide 12, etc. obtained by polycondensation reaction of lactams; diamines such as 1,6-hexanediamine, 2-methyl-1,5-pentanediamine, 1,7-heptanediamine, 2-methyl-1-6-hexanediamine, 1,8-octanediamine, 2-methyl-1,7-heptanediamine, 1,9-nonanediamine, 2-methyl-1,8-octanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediamine, m-xylylenediamine, and the like; and butanedioic acid, pentanedioic acid, hexanedioic acid, heptanedioic acid, octanedioic acid, etc. Examples include polyamide 6,6, polyamide 6,10, polyamide 6,11, polyamide 6,12, polyamide 6,T, polyamide 6,I, polyamide 9,T, polyamide 10,T, polyamide 2M5,T, polyamide MXD,6, polyamide 6,C, polyamide 2M5,C, etc., which are obtained as copolymers with dicarboxylic acids such as tanedioic acid, nonanedioic acid, decanedioic acid, benzene-1,2-dicarboxylic acid, benzene-1,3-dicarboxylic acid, benzene-1,4-dicarboxylic acid, cyclohexane-1,3-dicarboxylic acid, cyclohexane-1,4-dicarboxylic acid, etc.; and copolymers in which these are copolymerized (one example is polyamide 6,T / 6,I).

[0044] Among these polyamide resins, aliphatic polyamides such as polyamide 6, polyamide 11, polyamide 12, polyamide 6,6, polyamide 6,10, polyamide 6,11, and polyamide 6,12, and alicyclic polyamides such as polyamide 6,C and polyamide 2M5,C are more preferred.

[0045] Although there is no particular limitation on the terminal carboxyl group concentration of the polyamide resin, the lower limit is preferably 20 μmol / g, more preferably 30 μmol / g, and the upper limit is preferably 150 μmol / g, more preferably 100 μmol / g, and even more preferably 80 μmol / g.

[0046] In the polyamide resin, the ratio of carboxyl terminal groups to all terminal groups ([COOH] / [total terminal groups]) is more 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 desirably 0.30 or more from the viewpoint of dispersibility of the cellulose component in the composition, and is desirably 0.95 or less from the viewpoint of the color tone of the resulting composition.

[0047] The terminal group concentration of the polyamide resin can be adjusted by any known method, for example, by adding a terminal adjuster that reacts with terminal groups, such as a diamine compound, a monoamine compound, a dicarboxylic acid compound, a monocarboxylic acid compound, an acid anhydride, a monoisocyanate, a monoacid halide, a monoester, or a monoalcohol, to the polymerization solution so that the terminal group concentration is adjusted to a predetermined value during polymerization of the polyamide.

[0048] Examples of terminal modifiers that react with terminal amino groups include aliphatic monocarboxylic acids such as acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, pivalic acid, and isobutyric acid; alicyclic monocarboxylic acids such as cyclohexanecarboxylic acid; aromatic monocarboxylic acids such as benzoic acid, toluic acid, α-naphthalenecarboxylic acid, β-naphthalenecarboxylic acid, methylnaphthalenecarboxylic acid, and phenylacetic acid; and mixtures of any of these. Among these, from the standpoints of reactivity, stability of the blocked terminals, cost, and the like, one or more terminal modifiers selected from the group consisting of acetic acid, propionic acid, butyric acid, valeric acid, caproic acid, caprylic acid, lauric acid, tridecanoic acid, myristic acid, palmitic acid, stearic acid, and benzoic acid are preferred, with acetic acid being most preferred.

[0049] Examples of terminal modifiers that react with terminal carboxyl groups include aliphatic monoamines such as methylamine, ethylamine, propylamine, butylamine, hexylamine, octylamine, decylamine, stearylamine, dimethylamine, diethylamine, dipropylamine, and dibutylamine; alicyclic monoamines such as cyclohexylamine and dicyclohexylamine; aromatic monoamines such as aniline, toluidine, diphenylamine, and naphthylamine; and any mixtures thereof. Among these, one or more terminal modifiers selected from the group consisting of butylamine, hexylamine, octylamine, decylamine, stearylamine, cyclohexylamine, and aniline are preferred in terms of reactivity, boiling point, stability of the blocked terminals, cost, etc.

[0050] The concentrations of these amino terminal groups and carboxyl terminal groups are 1 From the viewpoint of accuracy and simplicity, it is preferable to determine the concentration of each end group from the integral value of the characteristic signal corresponding to the end group by H-NMR. As a method for determining the concentration of these end groups, the method described in JP-A-7-228775 is specifically recommended. When using this method, deuterated trifluoroacetic acid is useful as a measurement solvent. 1 The number of H-NMR scans required is at least 300, even when measured using an instrument with sufficient resolution. Alternatively, the concentration of terminal groups can be measured by a titration method such as that described in JP-A-2003-055549. However, in order to minimize the influence of additives, lubricants, etc., present in the mixture, 1 Quantitation by H-NMR is more preferred.

[0051] Preferred polyester resins as thermoplastic resins are not particularly limited, but may include one or more selected from polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyethylene naphthalate (PEN), polybutylene succinate (PBS), polybutylene succinate adipate (PBSA), polybutylene adipate terephthalate (PBAT), polyarylate (PAR), polyhydroxyalkanoic acid (PHA) (a polyester resin composed of 3-hydroxyalkanoic acid), polylactic acid (PLA), polycarbonate (PC), etc. Among these, more preferred polyester resins include PET, PBS, PBSA, PBT, and PEN, and even more preferred are PBS, PBSA, and PBT.

[0052] The terminal groups of the polyester resin can be freely changed by adjusting the monomer ratio during polymerization and the presence or absence and amount of a terminal stabilizer added. However, the ratio of carboxyl terminal groups to all terminal groups of the polyester resin ([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 the cellulose component in the composition, and is preferably 0.95 or less from the viewpoint of the color tone of the resulting composition.

[0053] Preferred polyacetal resins as thermoplastic resins include homopolyacetals derived from formaldehyde and copolyacetals containing trioxane as the main monomer and, for example, 1,3-dioxolane as a comonomer component. While both are usable, copolyacetals are preferred from the viewpoint of thermal stability during processing. In particular, the amount of the comonomer component (e.g., 1,3-dioxolane) is preferably within the range of 0.01 to 4 mol %. A more preferred lower limit for the comonomer component amount is 0.05 mol %, even more preferably 0.1 mol %, and particularly preferably 0.2 mol %. A more preferred upper limit is 3.5 mol %, even more preferably 3.0 mol %, particularly preferably 2.5 mol %, and most preferably 2.3 mol %. From the viewpoint of thermal stability during extrusion and molding, the lower limit is desirably within the above-mentioned range. From the viewpoint of mechanical strength, the upper limit is desirably within the above-mentioned range.

[0054] The thermoplastic resin (B) is preferably a polyamide resin, since it has an amino group at its end that easily reacts with the reducing-end aldehyde newly generated in the partially hydrolyzed fine cellulose (A).

[0055] The number-average molecular weight Mn of the thermoplastic resin (B) is not particularly limited, as long as it can be processed by molding methods commonly used in molding resin compositions, such as injection molding, extrusion molding, and blow molding. It is known that a low number-average molecular weight Mn of the thermoplastic resin (B) reduces the mechanical properties and impact resistance of the resin composition. However, the resin composition of the present invention has good adhesion to the partially hydrolyzed fine cellulose (A), making it applicable to thermoplastic resins with low number-average molecular weights Mn. For example, good mechanical strength can be obtained even when the number-average molecular weight Mn of the thermoplastic resin (B) is less than 14,000, less than 13,000, less than 12,000, less than 11,000, or less than 10,000. The number-average molecular weight is determined by gel permeation chromatography (GPC) in terms of polymethyl methacrylate.

[0056] In the resin composition, the mass ratio (A) / (B) of the amount of partially hydrolyzed fine cellulose (A) to the amount of thermoplastic resin (B) is preferably 0.01 or more, more preferably 0.02 or more, and even more preferably 0.03 or more, from the viewpoint of obtaining a good reinforcing effect by the partially hydrolyzed fine cellulose (A); and is preferably 1 or less, more preferably 0.70 or less, even more preferably 0.45 or less, and particularly preferably 0.25 or less, from the viewpoint of forming a good molded body.

[0057] [Other ingredients] The resin composition of the present invention may contain other additives such as antioxidants, crystal nucleating agents, compatibilizers, plasticizers, colorants, fragrances, pigments, flow control agents, leveling agents, conductive agents, antistatic agents, UV absorbers, UV dispersants, deodorizers, disinfectants, and flame retardants. The content of any additive may be appropriately set within a range that does not impair the desired effects of the present invention.

[0058] <Method of manufacturing resin composition> The resin composition of the present invention can be produced by various production methods. For example, a prepolymerized commercially available polymer (as thermoplastic resin (B)) may be kneaded with fine cellulose, or the raw material monomers of thermoplastic resin (B) may be polymerized in the presence of fine cellulose to produce a resin composition.

[0059] When a prepolymerized thermoplastic resin is used, either a method of partially hydrolyzing the fine cellulose in advance and then kneading it, or a method of partially hydrolyzing the fine cellulose in a kneader while continuously kneading it with the thermoplastic resin may be used.

[0060] In one aspect, the method for producing the resin composition of the present embodiment includes: Heating fine cellulose and / or plant fiber in a water-containing state and in a low-oxygen atmosphere to obtain a blending component containing partially hydrolyzed fine cellulose (A); and combining the blending components with a thermoplastic resin (B); The "low oxygen concentration atmosphere" of the present disclosure is an atmosphere in which the oxygen concentration is preferably 18% by volume or less, more preferably 10% by volume or less, even more preferably 5% by volume or less, and particularly preferably 1% by volume or less. In one embodiment, the blended components further contain hemicellulose (C) and / or lignin (D) derived from the raw material of the partially hydrolyzed fine cellulose (A) or added separately.

[0061] As a method for obtaining partially hydrolyzed fine cellulose (A) in advance, there is a method in which an aqueous dispersion of fine cellulose and / or a raw material for fine cellulose (e.g., plant fiber) itself, or a fine cellulose dispersion obtained by adding an acid and acidified to a pH of 1 to 7, is treated at room temperature or at a high temperature to proceed with acid hydrolysis. The acid used to acidify the dispersion may be an organic acid or an inorganic acid, or a solid acid. When an acid with oxidizing ability (e.g., nitric acid or a halogen oxoacid) is used, it may oxidize the fine cellulose and reduce the heat resistance and reinforcing effect, so it is preferable to add it in a small amount. In terms of being able to satisfactorily hydrolyze the amorphous portion while suppressing the hydrolysis of the crystalline portion to a low level, it is preferable to carry out acid hydrolysis under heating using an acid that has no or is relatively weak in oxidizing ability (inorganic acids such as dilute hydrochloric acid, dilute sulfuric acid, phosphoric acid, phosphorous acid, and carbonic acid; organic acids such as acetic acid, oxalic acid, citric acid, lactic acid, glutamic acid, aspartic acid, glycine, and phenol; and solid acids such as ion exchangers (Nafion (registered trademark), Amberlite (registered trademark), etc.), Y-type zeolite, β-type zeolite, mesoporous silica, and sulfonated carbon).

[0062] Alternatively, partial hydrolysis may be performed using an enzymatic reaction instead of acid hydrolysis. As the enzyme, cellulase (specifically, cellobiohydrolase, endoglucanase, or β-glucosidase) can be used, but endoglucanase is preferred because it can effectively hydrolyze the amorphous portion while suppressing hydrolysis of the crystalline portion to a low level.

[0063] The conditions for hydrolysis using these acids or enzymes can be appropriately selected within a range that does not cause the fine cellulose to be hydrolyzed to a low aspect ratio.

[0064] On the other hand, a method for partially hydrolyzing fine cellulose in a kneader includes feeding the fine cellulose in any form selected from an aqueous dispersion, a wet cake, and a dry powder into the kneader and mixing it with a thermoplastic resin. When the fine cellulose is used as a dry powder, an appropriate amount of water is separately introduced into the kneader. The kneader is not limited to the following, but examples thereof include a single-screw or multi-screw kneading extruder, a roll, a Banbury mixer, etc. Among these, a twin-screw extruder equipped with a pressure reducing device and a side feeder facility is preferred.

[0065] Various polymerization reactions can be used to obtain a resin composition by polymerizing raw material monomers of a thermoplastic resin in the presence of fine cellulose. Examples of polymerization reactions include radical polymerization, cationic polymerization, anionic polymerization, metathesis polymerization, polycondensation, polyaddition, and addition condensation. The fine cellulose may be partially hydrolyzed in advance as described above, or the partial hydrolysis may be carried out continuously and / or simultaneously with the polymerization reaction. The method of carrying out the partial hydrolysis and the polymerization reaction continuously and / or simultaneously is preferred because it contributes to shortening the production process and reducing costs.

[0066] The partial hydrolysis and the production of the resin composition are preferably carried out in a system with a low-oxygen atmosphere, which is created by replacing the atmosphere with an inert gas such as nitrogen or argon, or by reducing the pressure. By carrying out the partial hydrolysis and / or the production of the resin composition in an atmosphere with a low oxygen concentration, oxidation of the reducing ends newly generated by the thermal decomposition of the fine cellulose and the partial hydrolysis is less likely to occur, discoloration of the resin composition and a decrease in the reinforcing effect are suppressed, and a resin composition with little variation in quality can be provided.

[0067] The resin composition of the present invention can be used to obtain molded articles having good tensile properties and abrasion resistance, and is therefore suitable for a wide range of applications, including industrial machine parts (for example, electromagnetic equipment housings, roll materials, transport arms, medical equipment components, etc.), general machine parts, automobile, railway, and vehicle parts (for example, outer panels, chassis, aerodynamic components, seats, friction materials inside transmissions, etc.), ship components (for example, hulls, seats, etc.), aviation-related parts (for example, fuselages, main wings, tails, moving surfaces, fairings, cowls, doors, seats, interior materials, etc.), spacecraft and artificial satellite components (for example, motor cases, main wings, structures, antennas, etc.), and the like. They can be used in a wide range of applications, including: electrical and electronic components (for example, personal computer cases, mobile phone cases, office equipment, audiovisual equipment, telephones, facsimiles, home appliances, toys, etc.), construction and civil engineering materials (for example, steel bar substitutes, truss structures, cables for suspension bridges, etc.), everyday items, sports and leisure goods (for example, golf club shafts, fishing rods, tennis and badminton rackets, etc.), casing components for wind power generation, and container and packaging components, such as materials for high-pressure containers filled with hydrogen gas, such as those used in fuel cells.

[0068] The resin composition of this embodiment can also be molded into the form of a resin composite, such as a resin composite film. For example, the resin composite film is suitable for reinforcing laminates in printed wiring boards. Other applications of the resin composite include insulating tubes, insulating levers, arc-extinguishing plates, operating rods, insulating spacers, cases, wind tunnels, end bells, wind sinks, switch boxes, cases, crossbars, insulating shafts, fan blades, mechanical parts, transparent resin substrates, speaker diaphragms, eta diaphragms, television screens, fluorescent light covers, antennas, horn covers, radomes, cases, mechanical parts, wiring boards, electronic components for aircraft, rockets, and satellites, railway components, ship components, bathtubs, septic tanks, corrosion-resistant equipment, chairs, safety helmets, pipes, tank trucks, cooling towers, floating breakwaters, buried underground tanks, and containers.

[0069] Among these, sliding components (for example, sliding parts such as bearings, gears, and sliding members in industrial equipment, office equipment, etc., as well as household electrical equipment parts and automotive mechanical parts) can demonstrate superiority due to their improved properties compared to existing resin composites. [Example]

[0070] The present invention will be described in more detail below with reference to examples, but the scope of the present invention is not limited to the following examples. The main physical properties were measured by the following methods.

[0071] (1) Average fiber diameter of fine cellulose A dispersion of fine cellulose or a redispersion of fine cellulose obtained by dissolving and removing the resin from a resin composition was diluted to a concentration of 0.01% by mass, dropped onto a silicon wafer, and dried. Ten randomly selected locations were observed using a scanning electron microscope (SEM) at magnifications equivalent to 10,000 to 100,000 times, depending on the fiber diameter of the fine cellulose. Two lines, vertical and horizontal, perpendicular to each other were drawn in the resulting SEM image. The fiber diameters of the fibers intersecting the lines were measured from the enlarged image, and the number of fibers intersecting the lines and the fiber diameter of each fiber were counted. The number-average fiber diameter was calculated using the two vertical and horizontal measurement results for each image. The number-average fiber diameter was also calculated for nine other SEM images. The results from the 10 images were number-averaged to determine the average fiber diameter of the sample.

[0072] (2) Determination of the aspect ratio of fine cellulose As in (1) above, SEM observation was performed on 10 randomly selected locations. Two lines, one vertical and one horizontal, perpendicular to each other were drawn on the obtained SEM image, and the fiber length and fiber diameter of the fibers intersecting the lines were measured from the enlarged image. The number of fibers intersecting the lines and the fiber diameter of each fiber were counted. The aspect ratio was calculated from the obtained fiber length and fiber diameter, and it was determined whether or not low-aspect-ratio fine cellulose was contained. If the aspect ratio is high, the fine cellulose may be bent or not entirely contained within the image, making it difficult to determine an accurate aspect ratio. However, since the resin composition of the present invention exhibits its effect if the aspect ratio is high, it is sufficient to observe fine cellulose with a low aspect ratio. The aspect ratio was determined according to the following criteria. ◎: None of the 10 observation areas contained fine cellulose with an aspect ratio of 30 or less. ○: Fine cellulose with an aspect ratio of 30 or less is contained in any of the 10 observation areas. △: Fine cellulose with an aspect ratio of 30 or less is contained in all 10 observation areas.

[0073] (3) Measurement of molecular weight distribution of fine cellulose The molecular weight distribution of the fine cellulose was measured by gel permeation chromatography (GPC). The dispersion medium was removed from the fine cellulose dispersion or the re-dispersion of fine cellulose obtained by dissolving and removing the resin from the resin composition, and the cellulose residue was dissolved in a LiCl-containing dimethylacetamide eluent and filtered through a PTFE cartridge filter to prepare a sample solution. A TSKgel guard column Super AW-H (4.6 mm I.D. x 3.5 cm) and two TSKgel Super AWM-H (6.0 mm I.D. x 15 cm) columns (both manufactured by Tosoh) were connected to an HLC-8120GPC (manufactured by Tosoh), and peaks were detected using an RI detector. A calibration curve was created using a linear approximation line based on standard pullulan (manufactured by Shodex), and the molecular weight in terms of pullulan was calculated. The molecular weight can also be converted to the degree of polymerization by dividing it by the molecular weight of anhydroglucose unit (162), which is the monomer unit of cellulose.

[0074] The obtained GPC chart (horizontal axis: molecular weight, vertical axis: distribution value) was divided into low molecular weight and high molecular weight sides based on the peak top molecular weight, and the respective integrated values ​​(areas) were designated S1 for the low molecular weight side and S2 for the high molecular weight side, and the quantitative ratio of low molecular weight material (i.e., low-polymerization cellulose) to high molecular weight material (i.e., high-polymerization cellulose) was expressed as the S1 / S2 ratio.

[0075] (4) Quantitation of hemicellulose Quantitative analysis of hemicellulose was carried out as follows: The dispersion medium was removed from a dispersion of fine cellulose or a re-dispersion of fine cellulose obtained by dissolving and removing the resin from a resin composition, and the cellulose residue was recovered and dried at 105°C to obtain a dried sample, and the mass of the dried sample was measured as follows.

[0076] The dried cellulose residue was crushed and the resulting crushed sample was extracted with an alcohol (ethanol) / benzene mixed solvent in a Soxhlet extractor for 6 hours, followed by an additional 4 hours of extraction with an alcohol (ethanol) / benzene mixed solvent to obtain a defatted sample. 2.5 g of the defatted sample was mixed with 150 mL of distilled water, 1.0 g of sodium chlorite, and 0.2 mL of acetic acid and heated at 70-80°C for 1 hour. 1.0 g of sodium chlorite and 0.2 mL of acetic acid were added again and heated at 70-80°C for 1 hour. This process was repeated 3-4 times until the sample was decolorized to white. The resulting sample was filtered, washed with water and acetone, and dried at 105°C to obtain a holocellulose fraction. The mass of this holocellulose fraction was measured.

[0077] Next, 25 mL of 17.5% by weight sodium hydroxide solution was added to 1.0 g of the holocellulose fraction. After 3 minutes, the mixture was lightly crushed with a glass rod until swollen. The mixture was allowed to stand at 20°C. 30 minutes after the addition of the sodium hydroxide solution, 25 mL of distilled water was added, stirred for exactly 1 minute, allowed to stand at 20°C for 5 minutes, filtered through a glass filter, and washed until the filtrate was neutral. Further, 40 mL of 10% by weight acetic acid was added by suction filtration, followed by suction filtration of 1 L of boiling water. The washed sample was then dried at 105°C until a constant mass was obtained, yielding an α-cellulose fraction. The mass of this α-cellulose fraction was measured.

[0078] The hemicellulose content was calculated from the masses of the holocellulose fraction and the α-cellulose fraction determined as above using the following formula. Holocellulose (%) = holocellulose fraction (g) / sample (anhydrous basis) (g) × 100 α-cellulose (%) = α-cellulose fraction (g) / sample (anhydrous basis) (g) × 100 Hemicellulose (%) = Holocellulose (%) - α-cellulose (%)

[0079] (5) Quantitative determination of lignin Quantitative analysis of lignin was performed as follows. 3 mL of 72% by mass sulfuric acid was added to 300 mg of the defatted sample obtained during the above hemicellulose quantitative analysis. The mixture was then left to stand at 30°C for 1 hour, and then poured into a pressure bottle (125 mL capacity) with 84 mL of distilled water. The mixture was autoclaved at 120°C for 1 hour. Before cooling, the mixture was filtered through a glass filter to separate the acid-insoluble lignin, and the filtrate was also collected. The acid-insoluble lignin was washed with distilled water and dried at 105°C. The mass of the acid-insoluble lignin fraction was measured, and the absorbance of the filtrate was measured using a UV-visible spectrophotometer.

[0080] The contents of acid-insoluble lignin and acid-soluble lignin were calculated using the following formula. These were summed to determine the total lignin content. Acid-insoluble lignin (%) = Acid-insoluble lignin fraction (g) / Sample weight (anhydrous basis) (g) × 100 Acid-soluble lignin (%) = ((d × v × (As-Ab)) / (a × w)) × 100 Lignin (%) = Acid-insoluble lignin (%) + Acid-soluble lignin (%) d: Dilution ratio v : Filtrate constant volume (L) As: absorbance of the sample solution Ab: absorbance of blank solution a: absorption coefficient of lignin (110 L / g cm) w: Sample weight (anhydrous basis) (g)

[0081] (6) Measurement of number average molecular weight of thermoplastic resin (B) The number-average molecular weight of thermoplastic resins was measured by gel permeation chromatography (GPC). Known eluents can be used depending on the type of resin. Taking polyamide resin as an example, a sample solution was prepared by dissolving the thermoplastic resin used as a raw material for the resin composition in hexafluoroisopropanol (HFIP), or by dissolving the resin composition in HFIP and filtering the resulting solution through a PTFE cartridge filter. The eluent used was hexafluoroisopropanol with 0.1 mol / % sodium trifluoroacetate dissolved therein. One TSKgel guard column HHR-L (6 mm I.D. × 4 cm), one TSKgel-G2000HHR (7.8 mm I.D. × 30 cm), and one TSKgel-G3000HHR (7.8 mm I.D. × 30 cm) (all manufactured by Tosoh) were connected to an HLC-8320GPC (manufactured by Tosoh), and peaks were detected with an RI detector to determine the number average molecular weight in terms of polymethyl methacrylate.

[0082] (7) Molding conditions and mechanical property measurements Multipurpose test specimens were injection molded under conditions conforming to ISO294-3 and JIS K6920-2, and the tensile yield strength was measured for each of the raw resin (i.e., thermoplastic resin alone) and the resin composition (i.e., resin composition containing fine cellulose) in accordance with ISO527. Since polyamide-based materials change due to moisture absorption, they were stored in an aluminum moisture-proof bag immediately after molding to prevent moisture absorption.

[0083] (8) Abrasion resistance test (friction coefficient and abrasion depth) The multipurpose test specimens obtained under the above molding conditions were subjected to a sliding test using a reciprocating friction and wear tester (Toyo Seimitsu Co., Ltd., Model AFT-15MS) with a SUS304 test specimen (5 mm diameter ball) as the mating material. The test was conducted at a linear velocity of 50 mm / sec, a reciprocating distance of 50 mm, a temperature of 23°C, and a humidity of 50%. The friction coefficient was measured after 10,000 reciprocating cycles under a load of 9.8 N. The wear depth of the samples after the sliding test was measured using a confocal microscope (OPTELICS® H1200, Lasertec Corporation). The wear depth was calculated as the average of four measurements and rounded to the nearest decimal place. Measurements were conducted at equal intervals of 12.5 mm from the edge of the wear scar. Lower wear depth values ​​were considered to indicate better wear characteristics.

[0084] (9) Coloring of molded products The color tone of the multipurpose test piece obtained under the above molding conditions was evaluated visually.

[0085] [Production Example 1] (Preparation of Fine Cellulose Raw Material 1) After cutting cotton linter pulp and washing it with water to remove impurities, the purified pulp was added to pure water so that the solid content was 1.5% by mass, and the pulp was highly shortened and fibrillated by beating, and then defibrated at the same concentration using a high-pressure homogenizer (operating pressure: 10 treatments at 85 MPa) to obtain defibrated cellulose. Here, the beating process used a disc refiner, and the pulp was treated with a beating blade with high cutting function (hereinafter referred to as cutting blade) for 2.5 hours, and then beaten for another 2 hours using a beating blade with high defibration function (hereinafter referred to as defibration blade), to obtain a dispersion of fine cellulose raw material 1.

[0086] [Production Example 2] (Preparation of Fine Cellulose Raw Material 2) Cotton linter pulp was cut, washed with water to remove impurities, and the purified pulp was further soaked overnight in a 5% potassium hydroxide aqueous solution to remove hemicellulose. Except for this, beating and micronization treatment using a high-pressure homogenizer were carried out in the same manner as in Production Example 1, to obtain a dispersion of microcrystalline cellulose raw material 2. [Production Example 3] (Preparation of Fine Cellulose Raw Material 3) Except for using abaca pulp as the raw material, beating and pulverization treatment using a high-pressure homogenizer were carried out in the same manner as in Production Example 1, and a dispersion of fine cellulose raw material 3 was obtained.

[0087] [Production Example 4] (Preparation of Fine Cellulose Raw Material 4) The raw material was short fiber yarn, which had been prepared by thoroughly removing the oil from Tencel (registered trademark) cut yarn (3 mm long) supplied by Lenzing Fibers by washing it several times in water with a surfactant-added system. Except for this, beating and micronization treatment using a high-pressure homogenizer were carried out in the same manner as in Production Example 1, to obtain a dispersion of microfine cellulose raw material 4.

[0088] [Production Example 5] (Preparation of Fine Cellulose Raw Material 5) Commercially available DP pulp (average degree of polymerization 1600) was cut and hydrolyzed in a 10% by mass aqueous hydrochloric acid solution at 105°C for 5 minutes, and then filtered and washed to obtain an intermediate. Except for this, beating and refining treatment using a high-pressure homogenizer were carried out in the same manner as in Production Example 1, to obtain a dispersion of fine cellulose raw material 5.

[0089] [Production Example 6] (Preparation of Fine Cellulose Raw Material 6) According to the method described in Example 1 of JP-A-11-513425, finely chopped sea squirt pods were bleached with a solution of sodium hydroxide and sodium chlorite and stirred in a mixer to obtain a 1% by mass suspension. This suspension was processed 15 times at a pressure of 45 MPa using a high-pressure homogenizer (15MR-8TA manufactured by APV Gaulin) to obtain a dispersion of fine cellulose raw material 6.

[0090] [Production Example 7] (Preparation of Fine Cellulose Raw Material 7) After cutting cotton linter pulp, the purified pulp was washed with water to remove impurities, and the resulting pulp was added to pure water so that the solid content was 1.5% by mass. The pulp was then shortened and fibrillated by beating to obtain a dispersion of fine cellulose raw material 7 without performing high-pressure homogenizer treatment.

[0091] [Examples 1 to 12, Comparative Examples 1 to 5] Example 1 173 parts by mass of an aqueous dispersion of fine cellulose raw material 1, 216 parts by mass of a thermoplastic resin monomer (ε-caprolactam), 44 parts by mass of aminocaproic acid, and 0.59 parts by mass of phosphorous acid were mixed and stirred in a mixer until a uniform dispersion was obtained. Subsequently, nitrogen was passed through a sealed reaction vessel to replace the air. This mixed dispersion was gradually heated, and partial hydrolysis of the fine cellulose was carried out while emitting water vapor during heating. The temperature was raised to 240 ° C, and the mixture was stirred at 240 ° C for 1 hour to carry out a polymerization reaction. When the polymerization was completed, the resulting resin composition was discharged and cut into pellets. The resulting pellets were refined with hot water at 95°C and dried. The injection molding conditions were a cylinder temperature of 250°C and a mold temperature of 70°C. The results of various evaluations are shown in Table 1.

[0092] Example 2 A resin composition was produced in the same manner as in Example 1 except that 520 parts by mass of the aqueous dispersion of the fine cellulose raw material 1 was used, and molding and evaluation were carried out.

[0093] Example 3 A resin composition was produced in the same manner as in Example 1 except that 867 parts by mass of the aqueous dispersion of the fine cellulose raw material 1 was used, and molding and evaluation were carried out.

[0094] Example 4 A resin composition was produced in the same manner as in Example 1 except that 1733 parts by mass of the aqueous dispersion of the fine cellulose raw material 1 was used, and molding and evaluation were carried out.

[0095] Example 5 A resin composition was produced in the same manner as in Example 1 except that 2600 parts by mass of the aqueous dispersion of the fine cellulose raw material 1 was used, and molding and evaluation were carried out.

[0096] Example 6 A resin composition was produced in the same manner as in Example 1 except that 3,467 parts by mass of the aqueous dispersion of the fine cellulose raw material 1 was used, and molding and evaluation were carried out.

[0097] Example 7 A resin composition was produced in the same manner as in Example 1 except that 867 parts by mass of the aqueous dispersion of the fine cellulose raw material 2 was used, and molding and evaluation were carried out.

[0098] Example 8 A resin composition was produced in the same manner as in Example 1, except that 520 parts by mass of the aqueous dispersion of fine cellulose raw material 3 was treated at 240°C and 5 MPa for 1 minute before use, and then molding and evaluation were carried out.

[0099] Example 9 A resin composition was produced in the same manner as in Example 1, except that 867 parts by mass of the aqueous dispersion of fine cellulose raw material 3 was treated at 240°C and 5 MPa for 1 minute before use, and then molding and evaluation were carried out.

[0100] Example 10 A resin composition was produced in the same manner as in Example 1 except that 867 parts by mass of the aqueous dispersion of fine cellulose raw material 4 was used, and molding and evaluation were carried out.

[0101] Example 11 A resin composition was produced in the same manner as in Example 4, except that phosphorous acid was not added, and molding and evaluation were carried out.

[0102] Example 12 200 parts by mass of the aqueous dispersion of the fine cellulose raw material 1 and 5 parts by mass of acetic acid were placed in an autoclave, and nitrogen was passed through the sealed reaction vessel to replace the air. This mixed dispersion was heated at 120°C for 3 hours, then cooled to room temperature, centrifuged for deliquification, and washed to obtain a wet cake with a solids concentration of 5% by mass. This process was repeated to obtain 300 parts by mass of a wet cake with a solids concentration of 5% by mass. A pressure-controlled liquid injection nozzle was installed in cylinder 6 of a twin-screw extruder (STEER OMEGA30H, L / D = 60) with 13 cylinder blocks. Cylinder 1 was water-cooled, cylinder 2 was set to 80°C, cylinder 3 was set to 150°C, and cylinders 4 to 13 and the die were set to 250°C. Thermoplastic resin PA610 was supplied from cylinder 1 at a flow rate of 11.4 kg / h, and the above-mentioned wet cake with a solids concentration of 5% by mass was pumped into the extruder through the liquid injection nozzle of cylinder 6 at a flow rate of 200 cc / min. The extrusion was released to atmospheric pressure in cylinder 12, yielding fine cellulose-containing resin composition pellets. The resulting pellets were refined with hot water at 95°C and dried. The injection molding conditions were a cylinder temperature of 250°C and a mold temperature of 70°C. The results of various evaluations are shown in Table 1.

[0103] Example 13 A resin composition was produced in the same manner as in Example 12, except that a thermoplastic resin (PA12) was used, and molding and evaluation were carried out.

[0104] (Comparative Example 1) The aqueous dispersion of the fine cellulose raw material 1 was centrifuged to obtain a wet cake with a solids concentration of 5% by mass, which was then stirred at 70 rpm in an enclosed planetary mixer (Kodaira Seisakusho Co., Ltd., product name "ACM-5LVT", with hook-type stirring blades) and dried under reduced pressure at -0.1 MPa in a 40°C hot bath at 307 rpm for 5 hours to obtain a dry powder of the fine cellulose raw material 1. The dry powder was mixed with a thermoplastic resin (PA6) in a ratio of 5:95, melt-kneaded, and extruded into a strand to produce a resin composition, which was then molded and evaluated.

[0105] (Comparative Example 2) A resin composition was produced in the same manner as in Comparative Example 1, except that the dry powder of the fine cellulose raw material 1 and a thermoplastic resin (PA6) with a low average molecular weight were mixed in a ratio of 10:90 (mass ratio). Then, molding and evaluation were carried out.

[0106] (Comparative Examples 3 to 5) Commercially available thermoplastic resins (PA6: Comparative Example 3), (PA610: Comparative Example 4), and (PA12: Comparative Example 5) were each used alone and injection molded at a cylinder temperature of 250°C and a mold temperature of 70°C, and evaluation was carried out. The components and properties of the molded product are shown in Table 1.

[0107] [Table 1] [Industrial Applicability]

[0108] The resin composition according to the present invention can give molded articles having excellent tensile properties and abrasion resistance, and therefore can be suitably applied to industrial machine parts, general machine parts, automobile, railway, vehicle, etc. parts, ship parts, aviation-related parts, spacecraft, artificial satellite parts, electronic and electrical parts, building and civil engineering materials, daily necessities, sports and leisure goods, wind power generation casing parts, container and packaging parts, etc.

Claims

1. A method for producing a molded article of a resin composition comprising partially hydrolyzed fine cellulose (A), a thermoplastic resin (B) containing a polyamide resin, hemicellulose (C), and lignin (D), In the partially hydrolyzed fine cellulose (A) in the resin composition, cellulose in only a part of the surface layer including the surface of the microfibril bundles is hydrolyzed in the step of hydrolyzing the microfibril bundles, A method for producing a molded article from a resin composition, wherein the mass ratio (D) / (C) of lignin (D) / hemicellulose (C) is 0.1 to 10.

2. A molded article of a resin composition comprising partially hydrolyzed fine cellulose (A), a thermoplastic resin (B) containing a polyamide resin, hemicellulose (C), and lignin (D), The partially hydrolyzed fine cellulose (A) in the resin composition has a surface layer including the surface of the microfibril bundles partially hydrolyzed, and an inner layer not hydrolyzed, A molded article of a resin composition, wherein the mass ratio (D) / (C) of lignin (D) / hemicellulose (C) is 0.1 to 10.

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