Rice husk-derived material, resin composition, resin molded article, and method for producing rice husk-derived material

Abstract

The present invention provides a rice husk-derived material, a resin composition, and a method for producing the rice husk-derived material that can reduce environmental impact, possess adsorption properties, and have improved adhesion to resins. [Solution] The carbon content is 20 wt% to 50 wt%, and the silicon content as an amorphous silica component is 5 wt% to 30 wt%, and the particle size distribution obtained using a flow-type particle image analyzer contains 50% or more of particles with a size of 1.5 μm to 20 μm, the average pore diameter is 2 nm to 6 nm, and the BET specific surface area is 200 m². 2 It is 1 / g or more.

Description

Technical Field

[0001] The present disclosure relates to a rice husk-derived material, a resin composition, a resin molded body, and a method for producing a rice husk-derived material.

Background Art

[0002] Rice husks contain about 20% silica and have a lower carbon content compared to other biomass species. Also, due to its low calorific value per unit mass and high ash generation, it is not suitable for use as fuel and is generally treated as industrial waste. Therefore, by manufacturing various products using materials added with rice husks, the disposal cost of rice husks and the environmental load are being reduced.

[0003] For example, Patent Document 1 describes that a flame-retardant board is produced by kneading an inorganic aqueous composition such as gypsum, cement, and water glass with rice husks, placing the mixture in a mold, and subjecting it to pressure heating and drying. Also, Patent Document 2 describes that by burning plant-derived raw materials such as rice husks at a high temperature of 900°C or higher, the purity of amorphous silicon oxide can be increased and it can be used for concrete materials and cosmetic materials.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] Rice husk ash can also be added to polymer materials and the like as an alternative to carbon black and talc. Composite materials of rice husk ash and polymer materials can be recycled by burning the polymer component to recover the rice husk ash or by remelting the polymer material assuming resin material recycling, which is a great advantage. However, the rice husk ash produced by the conventional manufacturing method as described above has poor adhesion and compatibility with polymers, and has demerits such as deterioration of mechanical properties and increase in dimensional change. Therefore, the applications of materials compounded with polymers have been limited.

[0006] The technology disclosed herein has been made in view of such points, and provides a rice husk-derived material, a resin composition, a resin molded product, and a method for producing a rice husk-derived material that can reduce environmental impact, has adsorption characteristics, and has improved adhesion to resins.

Means for Solving the Problems

[0007] The inventor of the present application has found that by firing rice husks in a predetermined temperature range, a rice husk-derived material having characteristics such that the adhesion and compatibility with resins are good can be obtained.

[0008] That is, the rice husk-derived material of the present disclosure is a rice husk-derived material obtained by ashing rice husks, having a carbon content of 20 wt% or more and 50 wt% or less, and a silicon content contained as an amorphous silica component of 5 wt% or more and 30 wt% or less, including 50% or more of those having a particle size distribution obtained using a flow-type particle image analyzer of 1.5 μm or more and 20 μm or less, an average pore diameter of 2 nm or more and 6 nm or less, a BET specific surface area of 200 m 2 / g or more.

[0009] This rice husk-derived material reduces environmental impact by effectively utilizing rice husks, which are industrial waste, as a filler to replace carbon black and talc. Furthermore, resin compositions incorporating this rice husk-derived material exhibit excellent tensile elongation properties. The rice husk-derived material disclosed herein is thought to have higher compatibility and adhesion with resins than conventional rice husk-derived materials, and is expected to be applicable to a variety of uses. In addition, since the pores of this rice husk-derived material can be chemically modified, various surface treatments can be applied, making it highly versatile. Moreover, this rice husk-derived material can exhibit β-crystals when blended with polypropylene resin. By exhibiting β-crystals, improvements in tensile elongation properties can be expected.

[0010] The above-mentioned rice husk-derived material may also be used as a β-crystal nucleating agent for the formation of β-crystals in polypropylene.

[0011] The above-mentioned rice husk-derived material may be surface-treated with a silane coupling agent.

[0012] This disclosure further relates to a resin composition containing 5 wt% to 80 wt% of the above-mentioned rice husk-derived material and 20 wt% to 95 wt% of a polymer compound.

[0013] This disclosure further relates to a resin molded article obtained by molding the above-mentioned resin composition, wherein the resin molded article has a tensile elongation of 8% or more.

[0014] This disclosure further relates to a resin molded article obtained by molding the above resin composition, L measured using the SCE method * a * b * L in the color system * The value is 20.0 or less, and b * This relates to resin molded articles with a value of -0.2 or less.

[0015] This disclosure further relates to a method for producing a material derived from rice husks, The process involves soaking the raw material, rice husks, in an acidic aqueous solution, followed by a washing step where the husks are washed with water. The drying process involves drying the washed rice husks, It includes a firing process of firing at 200°C or higher but less than 500°C for 30 minutes or more, The present invention is characterized by obtaining a rice husk-derived material having a carbon content of 20 wt% to 50 wt% and a silicon content of 5 wt% to 30 wt% as an amorphous silica component.

[0016] This manufacturing method makes it possible to obtain a rice husk-derived material that, when blended with resin, exhibits excellent tensile elongation properties and can be applied to a variety of uses. This rice husk-derived material is highly versatile because its pores can be chemically modified. Furthermore, this rice husk-derived material can exhibit β-crystals when blended with polypropylene resin. By immersing the raw material rice husks in an acidic aqueous solution and then washing them, the carbonization process of the rice husks may differ from that of materials that do not undergo a washing process. [Effects of the Invention]

[0017] As described above, this disclosure makes it possible to provide a rice husk-derived material, a resin composition, and a method for producing a rice husk-derived material that can reduce environmental impact, have adsorption properties, and have improved adhesion to resins. [Brief explanation of the drawing]

[0018] [Figure 1] This is the particle size distribution of RHA300, a material derived from rice husks. [Figure 2] This is the particle size distribution of RHA400, a material derived from rice husks. [Figure 3] This is the particle size distribution of RHA600, a material derived from rice husks. [Figure 4] This is the particle size distribution of RHA800, a material derived from rice husks. [Figure 5] These are the results of the 29Si-CP / MAS solid-NMR analysis of each rice husk-derived material. [Figure 6] These are the results of 29Si-DP / MAS solid-NMR analysis of each rice husk-derived material. [Figure 7]This is the result of 29Si-CP / MAS solid-NMR analysis of a surface-treated rice husk-derived material. [Figure 8] These are the results of 29Si-CP / MAS solid-NMR analysis of carbon black and rice husk-derived materials that underwent surface treatment. [Figure 9] This is the thermogravimetric measurement result for a surface-treated rice husk-derived material. [Figure 10] This is the stress-strain curve of a molded resin product. [Figure 11] This is the stress-strain curve of a molded resin product. [Figure 12] This graph shows the elastic modulus of a molded resin product. [Figure 13] This is the X-ray diffraction spectrum of a molded resin body. [Figure 14] This graph shows the semi-crystallization time of a resin molded product. [Figure 15] This is an SEM image of the fracture surface of the resin molded product of Example 1. [Figure 16] This is an SEM image of the fracture surface of the resin molded product of Example 2. [Figure 17] This is the result of a scratch test on a resin molded product. [Figure 18] This is the stress-strain curve of a molded resin product. [Figure 19] This graph shows the relationship between the strain value and the β / α ratio of a resin molded product. [Figure 20] This graph shows the semi-crystallization time of a resin molded product. [Figure 21] This is the stress-strain curve of a molded resin product. [Modes for carrying out the invention]

[0019] The following describes in detail the rice husk-derived material, resin composition, and method for producing the rice husk-derived material as disclosed herein.

[0020] [Materials derived from rice husks] The rice husk-derived material of this disclosure is obtained by immersing rice husks of grains such as rice and wheat in an acidic aqueous solution, washing them with water, and then calcining them in a predetermined temperature range to turn them into ashing, and then crushing the resulting rice husk ash. It can be used as a filler added to polymer materials, etc., as a substitute for carbon black or talc. Furthermore, this rice husk-derived material can be used as a β-crystal nucleating agent for the formation of β-crystals in polypropylene.

[0021] From the viewpoint of heat resistance, mechanical properties, and compatibility with resins, the rice husk-derived material preferably has a carbon content of 20 wt% to 50 wt% and a silicon content of 5 wt% to 30 wt%, more preferably a carbon content of 25 wt% to 46 wt% and a silicon content of 7 wt% to 25 wt%. In the rice husk-derived material, silicon is contained as an amorphous silica component. The carbon and silicon content in the rice husk-derived material can be obtained by elemental analysis using SEM-EDS. The presence of amorphous silicon in the rice husk-derived material can be confirmed from the diffraction pattern of X-ray diffraction (XRD).

[0022] The rice husk-derived material is thought to be influenced by the hemicellulose component derived from brown rice contained in the rice husk, and this residual hemicellulose component is thought to contribute to improved adhesion to the resin and improved mechanical properties in the resin composition. The effect of this hemicellulose component is thought to be uniformly distributed in the rice husk-derived material because it is derived from brown rice contained in the rice husk. In contrast, even if brown rice components are added to conventional filler components, it is difficult to distribute them as uniformly as in the rice husk-derived material, and a similar effect cannot be achieved.

[0023] The rice husk-derived material undergoes a washing process described later, and it is believed that the acidic components remaining after the rice husks are calcined contribute to its compatibility with the resin.

[0024] The particle size distribution of the rice husk-derived material can be determined using a flow-type particle image analyzer. From the viewpoint of improving the adhesion to the resin, the particle size distribution of the rice husk-derived material preferably contains 50% or more of those having a particle size of 1.5 μm or more and 20 μm or less. More preferably, the particle size distribution of the rice husk-derived material contains 60% or more of those having a particle size of 1.5 μm or more and 20 μm or less. Still more preferably, the particle size distribution of the rice husk-derived material contains 65% or more of those having a particle size of 1.5 μm or more and 15 μm or less. Most preferably, the particle size distribution of the rice husk-derived material contains 75% or more of those having a particle size of 1.5 μm or more and 15 μm or less. In the particle size distribution of the rice husk-derived material determined using a flow-type particle image analyzer, the long axis length of the elliptical shape is taken as the equivalent ellipse region length, the short axis length is taken as the width, and among the ellipses of all equivalent areas, the selected ones are preferably measured as having the same aspect ratio as the boundary rectangle.

[0025] The rice husk-derived material is a porous body. For example, as a general method, by performing chemisorption measurement by the gas adsorption method, it is possible to determine powder properties such as specific surface area and pore distribution.

[0026] The BET specific surface area of the rice husk-derived material is preferably 200 m 2 / g or more from the viewpoints of adhesion to the resin, adaptability to surface treatment, and improvement of mechanical properties, and more preferably 200 m 2 / g or more and 400 m 2 / g or less, and still more preferably 200 m 2 / g or more and 300 m 2 / g or less. The specific surface area (m 2 / g) in the present disclosure is determined by chemisorption measurement by the gas adsorption method. Regarding the adsorption isotherm created by measuring the pressure and the adsorption amount of nitrogen molecules on the surface of the rice husk-derived material, the analysis relative pressure range is analyzed by the BET method determined under the conditions of adsorption isotherm type II or IV (ISO9277), and the BET specific surface area per weight (unit: m 2 / g) is obtained.

[0027] The rice husk-derived material mainly has mesopores with a pore size of 2 nm to 50 nm, and may also contain micropores with a pore size smaller than 2 nm. The average pore diameter of the rice husk-derived material is preferably 2 nm to 6 nm, and more preferably 2 nm to 4 nm, from the viewpoint of adhesion to resin and adaptability to surface treatment. The average pore diameter (nm) in this disclosure is determined by dividing the total pore volume per unit mass obtained by chemiadsorption measurement by the BET specific surface area.

[0028] The total pore volume (p / p0 = 0.990) of the rice husk-derived material is preferably 0.15 cm³ to ensure good surface treatment. 3 It is 0.17 cm² or more, and more preferably 0.17 cm². 3 / g or more 0.25cm 3 It is less than or equal to / g. The total pore volume in this disclosure is determined by using an adsorption isotherm of nitrogen gas prepared by chemiadsorption measurement by gas adsorption, and converting the amount of N2 gas adsorbed from the amount of gas adsorbed at a relative pressure p / p0 (p0: saturated vapor pressure) of 0.990 to the volume of N2 in liquid state.

[0029] From the viewpoint of achieving good surface treatment, the silicon in the rice husk-derived material preferably includes silicon in which three neutral oxygen atoms and one hydroxyl group are bonded (Q3 structure) and silicon in which two neutral oxygen atoms and two hydroxyl groups are bonded (Q2 structure). Conventionally, methods for analyzing these structures have included: 29 Si-CP / MAS solid-NMR or 29 Si-DP / MAS solid-state NMR is available.

[0030] Because the rice husk-derived material has the porous structure described above, surface treatment with various coupling agents can improve adhesion and compatibility with resins, and increase the mechanical strength of the cured product. The coupling agent is applied at a concentration of, for example, 0.5 × 10 per gram of rice husk-derived material. -4 mol ~ 10.0 × 10 -4 mol, preferably 1.0 × 10 -4 mol ~ 7.0 × 10 -4 mol, more preferably 1.2 × 10 -4mol ~ 6.2 × 10 -4 Surface modification is possible in moles. As a surface treatment agent, for example, a silane coupling agent can be used. Examples of silane coupling agents include alkyl alkoxysilanes, amino alkoxysilanes, epoxy alkoxysilanes, and alkylsilazane-based treatment agents. One type of silane coupling agent may be used, or two or more types may be used in mixture form.

[0031] Examples of alkyl alkoxysilanes include methyltrimethoxysilane, methyltriethoxysilane, ethyltrimethoxysilane, n-propyltrimethoxysilane, isobutyltriethoxysilane, n-hexyltrimethoxysilane, n-octyltriethoxysilane, and n-decyltrimethoxysilane.

[0032] Examples of amino-based alkoxysilanes include 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-phenyl-3-aminopropyltrimethoxysilane, N-2-(aminoethyl)-3-aminopropylmethyldimethoxysilane, and N-2-(aminoethyl)-3-aminopropyltrimethoxysilane.

[0033] Examples of epoxy alkoxysilanes include 3-glycidoxypropylmethyldiethoxysilane, 3-glycidoxypropyltriethoxysilane, 2-(3,4-epoxycyclohexyl)ethyltrimethoxysilane, 3-glycidoxypropylmethyldimethoxysilane, and 3-glycidoxypropyltrimethoxysilane.

[0034] Examples of alkylsilazane-based treatment agents include hexamethyldisilazane and vinylsilazane.

[0035] The surface treatment agent for the rice husk-derived material is preferably an amino-based alkoxysilane, specifically, for example, 3-aminopropyltriethoxysilane. When an acid-modified polypropylene resin is added to a resin composition as a filler dispersant to produce a resin molded article, the elastic modulus of the resin molded article decreases due to the acid-modified polypropylene resin. However, when a rice husk-derived material surface-treated with an amino-based alkoxysilane is added as a reinforcing agent for polypropylene to produce a resin molded article, imide bonds derived from the amino-based alkoxysilane are formed, thus improving the elastic modulus of the resin molded article even if an acid-modified polypropylene resin is present.

[0036] [Method for manufacturing materials derived from rice husks] The method for producing the rice husk-derived material of this disclosure includes a washing step of immersing the rice husks in an acidic aqueous solution and then washing them with water, a drying step of drying the washed rice husks, a calcination step of calcining the rice husks at 200°C or higher and less than 500°C for 20 minutes or more, and a pulverization step of freeze-pulverizing the calcined rice husk ash.

[0037] First, in the washing process, the rice husks are immersed in an acidic aqueous solution, for example, with a concentration of 1 to 10 wt%, and stirred at 30 to 70°C for 30 minutes or more. It is preferable to wash the rice husks immersed in the acidic aqueous solution with water at least twice. More preferably, washing with water is done two or three times. This is because a small amount of acid remains in the rice husks after the washing process, and the natural acid components contained in the rice husks allow for effective surface treatment of the rice husk-derived material. There are no particular limitations on the type or concentration of the acidic aqueous solution used, but from the viewpoint of reducing environmental impact, a citric acid aqueous solution is preferred.

[0038] Next, the washed rice husks are dried in the drying process. The drying temperature and drying time can be set arbitrarily, but for example, 100°C for 30 minutes.

[0039] Next, the dried rice husks are calcined in an electric furnace during the calcination process. The calcination temperature is preferably 200°C to 500°C, more preferably 250°C to 450°C, and even more preferably 300°C to 400°C, from the viewpoint of the desirable carbon and silicon content of the calcined rice husk ash, as well as the particle size distribution and average pore diameter. The calcination time is preferably 20 minutes to 60 minutes, and more preferably 20 minutes to 40 minutes. Furthermore, considering that resin compositions containing fillers are generally burned at 300-400°C to extract and reuse the fillers, it is preferable that the rice husk-derived material of this disclosure is also manufactured by calcining at 300°C or higher. Furthermore, considering that the hemicellulose component derived from brown rice contained in the rice husk may be present in the rice husk-derived material after calcination, potentially contributing to the adhesion to the resin and the mechanical properties of the resin composition, it is preferable to use calcination conditions such as a calcination temperature of 450°C or lower and a calcination time of 40 minutes or less, so as to prevent the complete combustion of the hemicellulose component in the rice husk.

[0040] Next, in the grinding process, it is preferable to grind the rice husks after calcination. Freeze grinding using liquid nitrogen is preferred for grinding, but other methods may also be used. A freeze grinder, ball mill, jet mill, etc., may be used as the grinder.

[0041] [Resin composition containing rice husk-derived material] The rice husk-derived material of this disclosure can be used as a substitute for conventional fillers and can be kneaded with various polymer compounds to form a resin composition. A resin composition containing the rice husk-derived material and polymer compounds of this disclosure is expected to enhance the mechanical properties of the polymer material. The polymer compounds used are not particularly limited, but examples include polypropylene, polyethylene, polyester, polyethylene terephthalate, synthetic fibers, and synthetic rubber. Preferably, the resin composition contains 20 wt% to 95 wt% of the polymer compound and 5 wt% to 80 wt% of the rice husk-derived material, more preferably 80 wt% to 95 wt% of the polymer compound and 5 wt% to 20 wt% of the rice husk-derived material, and even more preferably 85 wt% to 95 wt% of the polymer compound and 5 wt% to 15 wt% of the rice husk-derived material. By including 51 wt% or more of the rice husk-derived material, the molded resin body can be treated as combustible waste.

[0042] [Resin molded product containing rice husk-derived material] A resin molded article obtained from a resin composition containing the rice husk-derived material and a polymer compound of this disclosure has superior mechanical properties compared to a resin molded article obtained from a polymer compound that does not contain the rice husk-derived material of this disclosure. Mechanical properties include, for example, tensile elongation, stress-strain curve, modulus of elasticity, and yield stress. For example, a resin molded article obtained by melting a resin composition containing 90 wt% polypropylene resin and 10 wt% rice husk-derived material at 200°C for 4 minutes and extruding it in a mold at 60°C for 3 minutes preferably has a tensile elongation of 8% or more, more preferably 10% or more. There is no particular upper limit to the tensile elongation, but for example, it is preferable to have an upper limit of 20% or less from the viewpoint of the mechanical strength of the molded article. Furthermore, for example, a resin composition containing 90 wt% polypropylene resin and 10 wt% rice husk-derived material is melted at 200°C for 4 minutes, and extruded in a mold at 60°C for 3 minutes. The tensile modulus of the resin molded article obtained is preferably 1500 MPa or higher, more preferably 1800 MPa or higher. The tensile elongation and tensile modulus can be measured in accordance with JIS K7161 using a dumbbell-shaped test piece specified in JIS K7139 A12.

[0043] Furthermore, the resin molded article disclosed herein has an L value measured by the SCE method. * a * b * L in the color system * The value is 20.0 or less, and b * The value is -0.2 or less. Preferably, the resin molded article of this disclosure is measured by the SCE method L * a * b * L in the color system * The value is between 4.0 and 20.0, and b * The value is -0.2 or less, more preferably L * The value is between 4.0 and 19.2, and b * The value is -0.25 or less. Due to the rice husk-derived material, the resin molded body has the above-mentioned color characteristics and is equivalent to or darker than when carbon black is added in the same amount. Therefore, it can be used in various fields as a molded body with a jet-black, high-quality color tone. [Examples]

[0044] The following describes specific embodiments of the present invention.

[0045] [Manufacturing of materials derived from rice husks] In the production of the rice husk-derived material, the rice husks were first immersed in a 5 wt% aqueous solution of citric acid, stirred at 50°C for 1 hour, and then washed three times with water. After repeated use of the washing solution, the concentration of the citric acid solution after washing was less than 3 wt%. The washed rice husks were dried at 100°C for 30 minutes and then calcined in an electric furnace at a predetermined calcination temperature for 30 minutes. The calcined rice husk ash was placed in a freeze-pulverizer (JFC-400 model, manufactured by Nippon Analytical Industry Co., Ltd.) and freeze-pulverized by pre-cooling in liquid nitrogen for 5 minutes and then pulverizing for 5 minutes.

[0046] In evaluating the rice husk-derived material obtained after crushing, in the following description, the material that was calcined at 300°C in the calcination process will be referred to as RHA300 (RHA: Rice Husk Ash), the material that was calcined at 400°C as RHA400, the material that was calcined at 600°C as RHA600, and the material that was calcined at 800°C as RHA800. In addition, as comparative samples, we prepared a material that was calcined at 100°C and then crushed 20 times with a small grinder (manufactured by Stolz Co., Ltd., 3 mm blade) (hereinafter referred to as RHA100), carbon black (manufactured by Asahi Carbon Co., Ltd., Asahi #52) that was freeze-dried and crushed in the same way as RHA300, etc. (hereinafter referred to as CB), and untreated talc (manufactured by Nippon Talc Co., Ltd.).

[0047] [Elemental analysis by SEM-EDS] The obtained rice husk-derived materials (RHA100, RHA300, RHA400, RHA600, RHA800) were imaged using a scanning electron microscope (SEM), and elemental analysis was performed using energy-dispersive X-ray spectroscopy (EDS) to measure the carbon, oxygen, and silicon content. The measurement equipment and conditions are shown below, and the measurement results are shown in Table 1. SEM unit: Thermo Fisher Scientific Co., Ltd., Helios G4 PFIB CXe EDS detector: OcatnElite Super manufactured by Ametek EDAX Division (Measurement conditions) SEM-side acceleration voltage: 20kV, set current: 0.8nA, EDS-side elemental map condition pixels: 256×200 pixels, number of integrations: 128 frames, dwell time (beam dwell time): 50μs, time constant: 3.84μs (maximum set value)

[0048] [Table 1]

[0049] [Analysis by X-ray diffraction] The obtained rice husk-derived materials (RHA400, RHA600, RHA800) were measured using a powder X-ray diffractometer (RINT-2250VHF, manufactured by Rigaku Corporation). A broad diffraction pattern was obtained, confirming that silicon in the rice husk-derived materials is present in amorphous form. The X-ray diffraction measurement conditions are as follows. (Measurement conditions) Tube voltage: 40kV, Tube current: 400mA, Counter monochromator: Graphite curved, Divergent slit DS: 1°, Scattering slit SS: 1°, Photodetector slit: 0.3mm, Monochromator photodetector slit RSm: 0.8mm Vertical goniometer, standard sample holder, fixed to glass sample stage with liquid paraffin. Measurement method: FT (Step Scan), FT (Counting) time: 1 second, Step size: 0.01°, Scan axis: 2θ / θ, 2θ measurement range: 3~100° [Measurement of particle size distribution] The particle size distribution of the obtained rice husk-derived material can be obtained using a flow-type image analysis system. Here, the particle size distribution of RHA300, RHA400, RHA600, and RHA800 was obtained by measurement using a Micromeritics flow-type image analysis particle size and shape measuring system, Particle Insight 2.69. For the rice husk-derived material to be measured, the length of the major axis of the ellipse was defined as the equivalent elliptical region length, and the length of the minor axis as the width. From all ellipses of equivalent area, selected ones were assumed to have the same aspect ratio as the boundary rectangle for particle size measurement. The results are shown in Figures 1-4 and Table 2. In Table 2, the values ​​for the comparison samples talc, CB, and RHA100 represent the range of particle sizes observed by microscope (Keyence Corporation, VHX-7000, 1000x observation) because measurement with the flow-type image analysis system was difficult.

[0050] [Table 2]

[0051] [Measurement of BET specific surface area] The obtained rice husk-derived material was evaluated for its powder properties, such as specific surface area and pore distribution, by performing chemical adsorption measurements using the gas adsorption method. A MicrotracBEL BELSORP-MAXII034VP-MZ gas adsorption apparatus was used. Specifically, the rice husk-derived material was accurately weighed, sealed in an adsorption tube, degassed, and the nitrogen gas adsorption isotherm was determined under a liquid nitrogen atmosphere. This adsorption isotherm was then analyzed using the apparatus's analysis software compliant with ISO 9277 to determine the BET specific surface area (m²). 2 The value per gram ( / g) was calculated.

[0052] [Calculation of total pore volume] The average pore size of the obtained rice husk-derived material was determined by the following method. Using the nitrogen gas adsorption isotherm obtained by the gas adsorption apparatus described above, the total pore volume (cm³) was calculated by converting the amount of N2 gas adsorbed from the amount of gas adsorbed at a relative pressure p / p0 (p0: saturated vapor pressure) of 0.990 to the volume of N2 in liquid state. 3 The value per gram ( / g) was calculated.

[0053] [Calculation of average pore diameter] The average pore diameter was determined using the analysis software for the gas adsorption apparatus described above. The average pore diameter can be calculated using the BET specific surface area and total pore volume (gas adsorption method) obtained as described above, according to the following formula.

[0054] Average pore diameter (nm)=4V / S×1000 V: Total pore volume (gas adsorption method) (cm³) 3 / g) S:BET specific surface area (m 2 / g) Table 3 shows the BET specific surface area, total pore volume, and average pore diameter obtained by the above method for RHA300, RHA400, RHA800, and the comparative sample CB.

[0055] [Table 3]

[0056] [29 Si-NMR analysis] To confirm whether the obtained rice husk-derived material contains silicon with four neutral oxygen atoms bonded (Q4 structure), silicon with three neutral oxygen atoms bonded to one hydroxyl group bonded (Q3 structure), and silicon with two neutral oxygen atoms bonded to two hydroxyl groups bonded (Q2 structure), 29 Si-NMR analysis was performed. Specifically, 29 Si-CP / MAS solid-state NMR and 29 Analysis was performed using Si-DP / MAS solid-state NMR. 29 Si-CP / MAS solid-state NMR and 29 In Si-DP / MAS solid-spectrum NMR, silicon in the Q4 structure has a peak top around -110 ppm, silicon in the Q3 structure has a peak top around -100 ppm, and silicon in the Q2 structure has a peak top around -92 ppm. 29 The results of Si-CP / MAS solid-NMR are shown in Figure 5. 29 The results of Si-DP / MAS Solid-NMR are shown in Figure 6, and the relative ratios of peak integral values ​​are shown in Table 4. The measurement conditions are also described below. (Measurement conditions) Equipment: Varian 600PS, manufactured by Varian Corporation; Probe: 5.0 mm • CP / MAS method Contact time: 10ms, pulse waiting time: 5s External standard: 3-(trimethylsilyl)propionic-2,2,3,3,-d4 acid sodium salt (1.44ppm) Total count: 6000, Rotation speed: 7000Hz ·DP / MAS method Pulse waiting time: 10s External standard: 3-(trimethylsilyl)propionic-2,2,3,3,-d4 acid sodium salt (1.44ppm) Cumulative count: 5000, Rotation speed: 7000Hz

[0057] [Table 4]

[0058] [Surface treatment] The obtained rice husk-derived material RHA400 was subjected to surface treatment. Specifically, a 5 wt% aqueous solution of ethanol was added to the entire reaction solution so that the RHA400 content reached 10 wt%. Next, aminopropyltriethoxysilane (APTES) (Tokyo Chemical Industries Co., Ltd.) and n-octyltriethoxysilane (OTES) (Tokyo Chemical Industries Co., Ltd.) were added as coupling agents at a concentration of 0.5 wt% relative to RHA400, and the mixture was refluxed in a water / ethanol solvent at 80°C for 15 hours. In addition, hexamethyldisilazane (HMDS) (Tokyo Chemical Industries Co., Ltd.) was added as a coupling agent at a concentration of 20 wt% relative to RHA400 to allow for high coating, and the mixture was refluxed in a toluene solvent at 110°C for 14 hours. Washing after reflux was performed by centrifugation (9800 rpm × 10 min), followed by washing with 50 mL of ethanol twice and 50 mL of water once. For comparison, we also attempted surface treatment on CB using the same method.

[0059] [ 29 [Si NMR Spectral Analysis] As described above, the RHA400 surface-treated material allowed for good introduction of the silane coupling agent to the RHA400 surface. The introduction of the silane coupling agent was achieved through the following process: 29 This was confirmed by Si-CP / MAS solid-NMR analysis. Figure 7 shows the rice husk-derived material before and after surface treatment. 29 This is the result of the Si-CP / MAS solid-NMR analysis. 29 In the Si NMR spectrum, the peaks from -92.5 to 111.0 ppm are silicon-derived peaks from rice husk ash, the peaks at -58.3 ppm and -66.7 ppm are silicon-derived peaks from OTES and APTES, and the peak at 13.4 ppm is silicon-derived peak from HMDS. The position of the silicon peaks differs depending on the surface modification morphology of the coupling agents. 29The Si NMR spectra showed peaks originating from each silane coupling agent, confirming that the silane coupling agents APTES, OTES, and HMDS were successfully introduced to the RHA400 surface. Generally, of the two types of coupling agents mentioned above, aminopropyltriethoxysilane is highly basic and acts as a catalyst during treatment, making it easy to use in coupling treatments, while n-octyltriethoxysilane has low reactivity, making coupling treatment difficult. In the porous rice husk-derived material of this disclosure, it was confirmed that coupling treatment with n-octyltriethoxysilane, which is usually difficult to perform, was also easy. Figure 8 shows the surface-treated RHA400 and carbon black with attempted surface treatment. 29 This is the result of the Si-CP / MAS solid-NMR analysis. Similarly, in carbon black that underwent surface treatment, 29 Si-CP / MAS solid-NMR spectra did not show the peak observed with RHA400, confirming that the silane coupling agent could not be introduced to the surface. CB lacks hydroxyl groups and has a small specific surface area, which is thought to be the reason for the difficulty in surface modification.

[0060] [Thermogravimetric measurement (TG measurement)] As described above, TG measurements were performed on surface-treated and untreated RHA400 using a thermogravimetric analyzer (TG-MS: jMS-Q1500GC (TG-MS) manufactured by NEC Corporation, TG unit: STA449F1 manufactured by NETZSCH). The measurement results are shown in Figure 9. For the surface-treated RHA400, the amount of coupling agent (X) per gram of RHA was calculated from the rate of change in weight loss. Specifically, the amount of coupling agent (X) per gram of RHA was calculated using the following formula. The OTES-modified RHA400, APTES-modified RHA400, and HMDS-modified RHA400 are shown in Table 5, respectively. From these results, the modification ratio of OTES, APTES, and HMDS to RHA400 was 10:11:50, and as intended, HMDS was able to modify RHA400 with a higher coverage rate than OTES and APTES.

[0061]

number

[0062] [Table 5]

[0063] <Evaluation as a reinforcing agent for polypropylene> [Preparation of resin composition and preparation of test specimens] The rice husk-derived material obtained as described above and the filler used as a comparative sample were kneaded with polypropylene resin to prepare resin compositions, and the resin molded articles obtained using these resin compositions were evaluated. Details of the resin compositions, along with the tensile elongation results, are shown in Table 6. Examples using Novatec® PP SA08A manufactured by Nippon Polypropylene Co., Ltd. as the polypropylene resin are shown in Comparative Examples 1 to 6 and Examples 1 and 2. When an acid-modified polypropylene resin, which is a filler dispersant for resins, is added to the polypropylene resin, Yumex® manufactured by Sanyo Chemical Industries, Ltd. was used as the maleic acid-modified polypropylene resin, and this example is shown in Comparative Examples 7 to 11 and Example 3. In Comparative Example 4, brown rice was added to CB at a concentration of 3 wt%, which was then freeze-dried and used as the filler.

[0064] The resin was mixed with rice husk-derived material or filler using a highly controlled mixer (Laboplastmill® 10S100, manufactured by Toyo Seiki Seisakusho Co., Ltd.) under the conditions of 200°C for 5 minutes, a rotation speed of 60 rpm, and a torque of 0.9 (N·m). The obtained resin composition was placed into a Hand Truder® (manufactured by Toyo Seiki Seisakusho Co., Ltd.), melted at 200°C for 4 minutes, and then extruded at a mold temperature of 60°C for 3 minutes to obtain resin molded bodies for evaluation.

[0065] [Tensile test] Using a dumbbell-shaped resin molded body obtained through the above method as specified in JIS K7139-A12, the tensile elongation (elongation at break [%]) was measured in accordance with JIS K7161 under the conditions of a gauge length of 58 mm, a tensile speed of 1 mm / s, and a measurement temperature of 25°C. Furthermore, the yield stress (MPa) and tensile modulus (N / mm²) were determined from the stress-strain curve obtained from the tensile test. 2 The composition was determined. A Shimadzu AGX-100kNV was used as the tensile testing machine. The compositions and tensile test results for Comparative Examples 1-11 and Examples 1-3 are shown in Table 5.

[0066] [Table 6]

[0067] Compared to conventional fillers (Comparative Examples 2, 3, 8, and 9), the rice husk-derived materials of this disclosure (Examples 1-3) showed improved tensile elongation, particularly in Example 1. In Comparative Example 4, compared to Comparative Example 3, the addition of brown rice components to the CB improved tensile elongation, suggesting that components such as cellulose and sugars contributed to the improvement of mechanical properties. In Examples 1 and 2, since rice husks already contain components such as cellulose and sugars, the mechanical properties were improved without the addition of any other components. In Comparative Example 4, the error bars in the data were large, which is thought to be due to the brown rice components not being uniformly dispersed. In contrast, in Examples 1 and 2, the error bars were small, suggesting that cellulose and sugars were uniformly contained in the rice husks from the beginning. Figures 10 and 11 show the stress-strain curves, and Figure 12 shows the elastic modulus graph. Figure 12 also shows the tensile test results for Comparative Examples 27 and 28, which will be described later.

[0068] [Observation of β-crystals] The resin molded articles obtained through the above method, Comparative Examples 2, 3, 5, and 6, and Examples 1 and 2, were measured using a horizontal X-ray diffractometer (ULTIMA IV, manufactured by Rigaku Corporation). (Measurement conditions) X-ray source: Cu Kα rays, output: Max 2.0kW (normal operation 1.6kW), detector: one-dimensional semiconductor detector (D / Tex Ultra), using a Cu Kβ filter. As shown in Figure 13, a characteristic peak indicating β-crystalline polypropylene was observed only in the spectra of Comparative Examples 5 and 6 and Examples 1 and 2, which included RHA. Similarly, when measurements were performed on the resin molded articles of Comparative Examples 7-11 and Example 3, a characteristic peak indicating β-crystalline polypropylene was observed only in the spectra of Comparative Examples 10 and 11 and Example 3, which included RHA. From these results, it was confirmed that the rice husk-derived material of this disclosure can be used as a β-crystal nucleating agent for polypropylene. By using the rice husk-derived material of this disclosure together with polypropylene to induce β-crystal formation, an improvement in tensile elongation properties can be expected.

[0069] [Flash DSC Measurement] Isothermal crystallization measurements were performed on the resin molded articles of Comparative Example 1, Comparative Example 3, and Examples 1 and 2 using a differential scanning calorimeter (METTLER TOLEDO, Flash DSC). Specifically, 50-80 ng of molded article specimens were placed in a dedicated aluminum pan and cooled from 230°C to 2000°C per second. The time it took for half of the crystallized area to crystallize was determined as the semi-crystallization time. The measurement results of the semi-crystallization time are shown in Figure 14. In Figure 14, t 1 / 2 is the semi-crystallization time. As shown in Figure 14, the crystallization rate of polypropylene (Comparative Example 1) increases when a filler is included, but the crystallization rate is lower when RHA is included (Examples 1 and 2) than when CB is included (Comparative Example 3). From these results, it is considered that using the rice husk-derived material of this disclosure has the effect of reducing polymer crystallinity, which is a challenge in material recycling.

[0070] [Observation of the fracture surface] The fracture surfaces of the resin molded articles of Example 1 and Example 2 were observed using a scanning electron microscope (SEM). Figure 15 shows the fracture surface of the resin molded article of Example 1, and Figure 16 shows the fracture surface of the resin molded article of Example 2. As shown in Figures 15 and 16, the rice husk-derived material located in the center of the image is in close contact with the surrounding polypropylene resin, and it was visually confirmed that the degree of adhesion was slightly less in Example 2 than in Example 1. From these results, it can be said that the interface state (adhesion) between the resin and the rice husk-derived material changes depending on the firing temperature during the production of the rice husk-derived material.

[0071] [Scratch Test] Comparative Examples 2, 3, 5, and 6, as well as Examples 1 and 2, were evaluated using scratch testing. (Measurement conditions) Test equipment: NANOVEA CB-500 scratch tester Measurement conditions: Indenter: φ200μm diamond indenter Load: Apply a load at a speed of 10 mm / min with a gradient of 0 to 5 N. Distance: 5mm The results of this test are shown in Figure 17. As shown in Figure 17, the molded articles of Examples 1 and 2 containing RHA were less susceptible to scratching than the molded articles of Comparative Examples 2 and 3 containing other fillers. Furthermore, the molded articles of Examples 1 and 2 containing RHA, fired at 300°C or 400°C, were less susceptible to scratching than Comparative Example 6 containing RHA, fired at 800°C.

[0072] <Evaluation as a reinforcing agent for polyethylene> [Preparation of resin composition and preparation of test specimens] Resin compositions were prepared by kneading rice husk-derived materials and fillers (as comparative samples) with polyethylene resin, and the resin molded articles obtained using these resin compositions were evaluated. Details of the resin compositions, along with the tensile test results, are shown in Table 7. Novatec HD HJ491, manufactured by Nippon Polyethylene Co., Ltd., was used as the polyethylene resin. In Comparative Examples 13, 15, 17, and 19, and Examples 5 and 7, a compatibilizer for polyester resins was added.

[0073] The resin was mixed with rice husk-derived material or filler using a highly controlled mixer (Laboplastmill® 10S100, manufactured by Toyo Seiki Seisakusho Co., Ltd.) at 200°C for 5 minutes at a rotation speed of 60 rpm. The resulting resin composition was placed in a hand truder® (manufactured by Toyo Seiki Seisakusho Co., Ltd.), melted at 200°C for 4 minutes, and then extruded at a mold temperature of 60°C for 3 minutes to obtain resin molded bodies for evaluation.

[0074] [Tensile test] Using dumbbell-shaped resin molded bodies specified in JIS K7139-A12 obtained through the above method, tensile tests were performed in accordance with JIS K7161 under the conditions of a gauge length of 58 mm, a tensile speed of 50 mm / s, and a measurement temperature of 25°C. A Shimadzu AGX-100kNV tensile testing machine was used. Table 6 shows the compositions and tensile test results for Comparative Examples 12-19 and Examples 4-7. No improvement in properties was observed in formulations with added compatibilizers. Examples 4-7, which included RHA300 and RHA400, showed properties equivalent to those of the comparative examples containing talc and CB, indicating that RHA300 and RHA400 can be used as substitutes for talc and CB.

[0075] [Table 7]

[0076] <Evaluation as a reinforcing agent for polyethylene terephthalate> [Preparation of resin composition and preparation of test specimens] Resin compositions were prepared by kneading rice husk-derived materials and fillers (as comparative samples) with polyethylene terephthalate resin, and resin molded articles obtained using these resin compositions were evaluated. Details of the resin compositions, along with the bending strain test results, are shown in Table 8. PET resin EFG6C manufactured by Bell Polyester Products Co., Ltd. was used as the polyethylene terephthalate resin. In Comparative Examples 21 and 23, and Examples 9 and 11, a compatibilizer for polyester resins was added. This compatibilizer was the same as that used in the evaluation of the polyethylene reinforcing agent described above.

[0077] The resin was mixed with rice husk-derived material or filler using a highly controlled mixer (Laboplastmill® 10S100, manufactured by Toyo Seiki Seisakusho Co., Ltd.) at 270°C for 5 minutes at a rotation speed of 60 rpm. The resulting resin composition was placed into a Hand Truder® (manufactured by Toyo Seiki Seisakusho Co., Ltd.), melted at 270°C for 4 minutes, and then extruded at a mold temperature of 50°C for 3 minutes to obtain resin molded bodies for evaluation.

[0078] [Bending test] Using the dumbbell-shaped resin molded bodies specified in JIS K7139-A12 obtained through the above method, a three-point bending test was performed in accordance with JIS K7171 under the conditions of a support distance of 32 mm, a tensile speed of 2 mm / s, and a measurement temperature of 25°C. A Shimadzu AGX-100kNV tensile testing machine was used. Table 7 shows the compositions and bending strain test results for Comparative Examples 20-23 and Examples 8-11. No improvement in properties was observed in formulations with added compatibilizers. Examples 8-11, which included RHA300 and RHA400, showed improved elongation compared to Comparative Examples 22 and 23, which included CB.

[0079] [Table 8]

[0080] <Evaluation of surface-treated rice husk-derived materials as reinforcing agents for polypropylene> Using the above method, the surface-treated rice husk-derived material RHA400 was melted with polypropylene resin at 210°C for 4 minutes, and the resin molded articles obtained by extrusion molding in a 60°C mold for 3 minutes were evaluated. In Example 12 and Comparative Example 24, aminopropyltriethoxysilane (APTES) (Tokyo Chemical Industries Co., Ltd.) was added to the surface-treated rice husk-derived material RHA400 to a concentration of 0.5 wt% relative to RHA400. In Examples 13 and 14, n-octyltriethoxysilane (OTES) (Tokyo Chemical Industries Co., Ltd.) was added to the surface-treated rice husk-derived material RHA400 to a concentration of 0.5 wt% relative to RHA400. In addition, in Example 15 and Comparative Example 25, hexamethyldisilazane (HMDS) was added to the surface-treated rice husk-derived material RHA400 at a concentration of 20 wt% relative to RHA400. Furthermore, maleic acid-modified polypropylene resin (manufactured by Sanyo Chemical Industries, Ltd., registered trademark Yumex) was kneaded into the resin compositions of Comparative Examples 24 and 25 and Example 14 as a filler dispersant. The resins used and the methods for manufacturing the resin molded articles were the same as in Example 1. Details of the resin compositions, along with the results of tensile tests and X-ray diffraction, are shown in Table 9.

[0081] [Table 9]

[0082] [Tensile test] The tensile modulus of resin molded articles containing the surface-treated rice husk-derived material RHA400 obtained by the above method was measured to confirm their mechanical properties. The measurement conditions were the same as in Example 1. Figure 18 shows the measurement results of the tensile modulus. For comparison of mechanical properties, the results are also shown for Comparative Example 1', a molded article containing only polypropylene resin (composition is the same as Comparative Example 1, but the resin melting temperature is 210°C for 4 minutes); Comparative Example 7', a molded article containing only polypropylene resin and maleic acid-modified polypropylene resin as a filler dispersant (composition is the same as Comparative Example 7, but the resin melting temperature is 210°C for 4 minutes); and Example 2', a composition containing the rice husk-derived material RHA400 that has not been surface-treated with a coupling agent, molded under the same conditions (composition is the same as in Example 2, but the resin melting temperature is 210°C for 4 minutes). As shown in Table 9 and Figure 18, the tensile modulus of polypropylene resin was significantly improved when it contained surface-treated rice husk-derived material RHA400 compared to when it contained untreated rice husk-derived material RHA400 (Examples 12, 13, 15). Furthermore, when the polypropylene resin contained surface-treated rice husk-derived material RHA400 with aminopropyltriethoxysilane (APTES), a high tensile modulus was confirmed even when it contained maleic acid-modified polypropylene resin (Example 14).

[0083] [Observation of β-crystals] The resin molded articles obtained through the above method were measured using a horizontal X-ray diffractometer (ULTIMA IV, Rigaku Corporation). The measurement conditions were the same as in Example 1. In the spectra of Examples 2', 12-15, and Comparative Examples 24 and 25, which included RHA, a characteristic peak indicating β-crystal polypropylene was observed around 16°(2θ). As shown in Table 9, the β / α ratio was calculated from the spectral intensity. From these results, it was confirmed that surface-treated rice husk-derived materials can also be used as β-crystal nucleating agents for polypropylene. Furthermore, it was confirmed that the relationship between the strain value measured by the tensile test described above and the β / α ratio is shown in Figure 19. By using the rice husk-derived material of this disclosure together with polypropylene to induce β-crystal formation, improvements in the impact resistance and ductility of the resin molded articles can be expected.

[0084] [DSC measurement] For the resin molded body obtained through the above method, isothermal crystallization measurement was performed using a high-sensitivity differential scanning calorimeter (DSC7000X manufactured by Hitachi High-Tech Corporation). The measurement method is as follows. A sample of 1.5 to 2.0 mg was precisely weighed and measured using a dedicated aluminum pan. The measurement temperature was such that the sample melted at 210°C was cooled at 15°C / min to a predetermined temperature (128 to 140°C), and isothermal holding was performed for a maximum of 40 minutes to measure the half-crystallization time. The measurement results of the half-crystallization time are shown in Figure 20. As shown in Figure 20, in Comparative Example 25, the crystallization rate was the fastest, and in Example 14, the crystallization rate was the slowest, and the difference was significant. Example 2', Comparative Example 24, Examples 12, 13, and 15 showed crystallization rates at an intermediate level between Comparative Example 25 and Example 14. The rice husk-derived material of the present disclosure can change the crystallization rate depending on the type of coupling agent used for surface treatment. An improvement in the impact resistance and ductility of the resin molded body can be expected. A polypropylene resin molded body using a rice husk-derived material surface-treated with aminopropyltriethoxysilane and using maleic acid-modified polypropylene resin as a filler dispersant has a fast crystallization rate, so it is possible to shorten the molding cycle time during manufacturing. By subjecting the rice husk-derived material of the present embodiment to surface treatment, the crystallinity of the polymer can be controlled, and the recyclability and moldability can be enhanced.

[0085] <Comparison by the presence or absence of treatment before and after firing of RHA> In the production of the rice husk-derived material of this embodiment, first, the rice husks are immersed in a 5 wt% aqueous solution of citric acid, followed by a washing step in which they are washed with water, and then, after firing at a predetermined firing temperature, a grinding step in which freeze-grinding is performed. To confirm how the washing and grinding steps before and after firing affect the mechanical properties of the resin molded body, tensile tests were performed on the samples shown in Table 10 using the same method as in Example 1, and the stress-strain curves were compared. Specifically, tensile tests were conducted on the resin molded articles of Example 2, which were manufactured using RHA400 produced by washing and firing rice husks at 400°C and then pulverizing them; the resin molded articles of Comparative Example 26, which were manufactured in the same manner as Example 2 using RHA400 produced by washing and firing rice husks at 400°C without the pulverizing process (no post-treatment); and the resin molded articles of Comparative Example 27, which were manufactured in the same manner as Example 2 using RHA400 produced by firing rice husks at 400°C without the washing process and then the pulverizing process (no pre-treatment). Stress-strain curves were obtained for each of these. The results are shown in Figure 21. As shown in Figure 21, the elastic modulus was the same for all, but the elongation characteristics were best in Example 2. The elongation characteristics are thought to be particularly improved by the pulverizing process. The tensile test results for Comparative Example 27 are shown in Figure 12.

[0086] [Table 10]

[0087] <Evaluation of blackness> The blackness of the resin molded articles of this embodiment, Examples 1 to 3, and Comparative Examples 3, 4, 9, 27, and 28 was evaluated. Comparative Example 28 was a molded article manufactured in the same manner as in Example 1 using RHA300 (no pretreatment) which was fired at 300°C without washing the rice husks and then subjected to a crushing process. The tensile test results for Comparative Example 28 are shown in Figure 12. The blackness was evaluated by the following method. (Evaluation method) Test equipment: Konica Minolta CM-5 colorimeter Measurement conditions: Light source: D65 Viewing angle: 2 degrees Colorimeter diameter: 3mmφ Color measurement method: SCE method Number of measurements: N=5 The results of this test are shown in Table 11. * The value is the measured value of the reflectance, L * A smaller value indicates a higher degree of blackness. * The value is in the yellow direction, -b * The value is the measurement in the blue direction. L * Value and b * Focusing on the values, in Examples 1-3, the L was lower than that of the resin molded articles containing CB as a filler (Comparative Examples 3, 4, and 9). * The value was small and the blackness was high. Furthermore, in Examples 1-3, -b was lower than in Comparative Examples 3 and 9. * The values ​​were high and the product had a bluish tint. From these results, it can be said that the resin molded product of this embodiment can be used as a substitute for CB, and that it has a higher degree of jet blackness and a more luxurious black color than CB. Comparative Examples 27 and 28, which used RHA that had not undergone the washing process, also had the same black color characteristics as Examples 1 to 3.

[0088] [Table 11]

[0089] <Consideration of filling amount> In the resin composition containing the rice husk-derived material and polymer compound of this disclosure, the amount of rice husk-derived material that can be filled per 100 wt% of the resin composition was investigated. In Example 16, a resin composition containing 51 wt% washed RHA400 and 49 wt% polypropylene was kneaded at 200°C for 5 minutes and molded at a melting temperature of 240°C and a mold temperature of 80°C for 5 minutes. In Example 17, a resin composition containing 51 wt% washed RHA400, 47.53 wt% polypropylene, and 1.47 wt% maleic acid-modified polypropylene as a dispersant was molded under the same conditions as in Example 16. In Example 18, a resin composition containing 80 wt% washed RHA400 and 20 wt% polypropylene was kneaded at 200°C for 5 minutes. In Comparative Example 29, a resin composition containing 80 wt% unwashed RHA400 and 20 wt% polypropylene was melt-kneaded under the same conditions as in Example 18. For moldability, the molded product was visually inspected to determine if it could be molded using a mold. In Examples 16 and 17, the moldability was deemed acceptable, similar to Example 1, and was therefore rated as ○. Example 17 exhibited better moldability with less unevenness than Example 16. This is thought to be because the inclusion of maleic acid-modified polypropylene in Example 17 improved the compatibility and dispersibility between the resin and RHA400. Example 18 was black and glossy, and was deemed to have no moldability issues, so was rated as ○. In Comparative Example 29, which used unwashed RHA400, the compatibility between the resin and RHA400 was very poor, resulting in the formation of a brown, dull, and brittle solid. The moldability was judged to be poor and was rated as ×. From these results, it can be said that the compatibility of RHA400 with resin improves after undergoing the washing process.

[0090] [Table 12]

Claims

1. It is a rice husk-derived material obtained by ashifying rice husks, The carbon content is 20 wt% or more and 50 wt% or less, and the silicon content included as amorphous silica is 5 wt% or more and 30 wt% or less. The particle size distribution obtained by the flow-type image analysis device contains 50% or more particles with a particle size of 1.5 μm to 20 μm. Average pore diameter is between 2 nm and 6 nm. BET specific surface area is 200 m ２ Rice husk-derived material with a content of 1 / g or more.

2. In the rice husk-derived material according to claim 1, A rice husk-derived material used as a β-crystal nucleating agent to induce β-crystal formation in polypropylene.

3. In the rice husk-derived material according to claim 1, A rice husk-derived material that has been surface-treated with a silane coupling agent.

4. A resin composition comprising 5 wt% to 80 wt% of the rice husk-derived material described in claim 1 and 20 wt% to 95 wt% of a polymer compound.

5. A resin molded article obtained by molding the resin composition described in claim 4, wherein the resin molded article has a tensile elongation of 8% or more.

6. A resin molded article obtained by molding the resin composition described in claim 4, L measured using the SCE method ＊ a ＊ b ＊ L in the color system ＊ The value is 20.0 or less, and b ＊ A resin molded product with a value of -0.2 or less.

7. A method for producing a material derived from rice husks, The process involves soaking the raw material, rice husks, in an acidic aqueous solution, followed by a washing step where the husks are washed with water. The drying process involves drying the washed rice husks, It comprises a firing process of firing at 200°C or higher but less than 500°C for 20 minutes or more, A method for producing a rice husk-derived material, wherein the carbon content is 20 wt% or more and 50 wt% or less, and the silicon content contained as amorphous silica is 5 wt% or more and 30 wt% or less.

Images