Powdery cellulose

Abstract

To provide a powdery cellulose that exhibits favorable flowability when prepared as a resin composition and satisfactory dispersibility in the resin composition.SOLUTION: A powdery cellulose for molding resin materials has a particle diameter D50 of 10 to 100 μm, an angle of repose of 55° or less, and an angle of collapse of 38° or less. It is preferable that a difference angle, represented by a difference between the angle of repose and the angle of collapse, is 10 to 30°, more preferably that the aspect ratio is 1.0 to 6.0, and still more preferably that the intrinsic viscosity is 380 ml / g or less.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to powdered cellulose. [Background technology]

[0002] In recent years, powdered cellulose has been used as a reinforcing agent for resin materials such as rubber and plastics (for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-012875 Summary of the Invention [Problem to be solved by the invention]

[0004] One of the applications of resin compositions containing powdered cellulose is for exterior parts such as housings for home appliances and interior and exterior parts for automobiles. The properties required for exterior parts include mechanical strength such as tensile strength, flexural strength, and impact strength, and the resin must have good fluidity during part molding. However, resin compositions containing typical cellulose fibers have low fluidity and, due to the low dispersibility of the cellulose fibers in the resin composition, they do not exhibit the desired mechanical strength.

[0005] The present invention has been made in view of the above, and an object of the present invention is to provide a powdery cellulose that has good fluidity when made into a resin composition and good dispersibility in the resin composition. [Means for solving the problem]

[0006] The present invention provides the following [1] to [5]. [1] Powdered cellulose for use in molding resin materials, having a particle diameter D50 of 10 to 100 μm, an angle of repose of 55° or less, and a collapse angle of 38° or less. [2] The powdery cellulose for use as a molding resin material according to [1], wherein the difference angle between the angle of repose and the angle of collapse is 10 to 30°. [3] The powdery cellulose for use as a molding resin material according to [1], having an aspect ratio of 1.0 to 6.0. [4] The powdery cellulose for use in molding resin materials according to [1], having an intrinsic viscosity of 380 ml / g or less. [5] A method for producing powdered cellulose for use in molding resin materials, having a particle size D50 of 10 to 100 μm, an angle of repose of 55° or less, and a collapse angle of 38° or less, characterized in that the raw material pulp undergoes an acid hydrolysis step during pulverization. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide powdery cellulose that has good flowability when made into a resin composition and good dispersibility in the resin composition. DETAILED DESCRIPTION OF THE INVENTION

[0008] [1. Powdered cellulose] The particle diameter D50 is 10 to 100 μm, the angle of repose is 55° or less, and the angle of collapse is 38° or less.

[0009] [1.1. Particle size] The particle size of powdered cellulose can be expressed as the particle size distribution at the 10%, 50%, and 90% cumulative values ​​of the volume distribution (10% diameter, 50% diameter, and 90% diameter, D.10, D.50, and D.90, respectively). In this specification, the particle size refers to the D.50 value obtained by wet measurement (with ultrasonic irradiation).

[0010] The particle size D.50 of the present invention is preferably 10 to 100 μm, more preferably 15 to 80 μm, and even more preferably 20 to 60 μm. Generally, the larger the particle size, the more likely the fibers are to become entangled. Furthermore, by keeping the particle size within the above range, when the fiber is added to resins, rubbers, etc., the strength can be appropriately improved without impairing their properties.

[0011] [1.2. Average fiber width (μm), average fiber length (μm), average fiber length / average fiber width (L / D, aspect ratio) of powdered cellulose] The powdered cellulose preferably has an average fiber length of 40 to 200 μm, more preferably 50 to 150 μm. When the average fiber length is 40 to 150 μm, it can maintain an appropriate fluidity when kneaded with a resin.

[0012] The average fiber width of the powdered cellulose is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more, and the upper limit is usually 50 μm or less, preferably 40 μm or less, more preferably 30 μm or less.

[0013] The average fiber length / average fiber width (L / D, aspect ratio) of the powdered cellulose is preferably 1.0 to 6.0, more preferably 2.0 to 5.0, and even more preferably 2.0 to 4.0. Adding a fibrous filler to a resin reduces the fluidity and makes molding difficult, but when the L / D of the powdered cellulose is 1.0 to 6.0, a resin composition containing the powdered cellulose has improved tensile strength and flexural strength compared to the resin alone, and the resin composition can maintain appropriate fluidity.

[0014] The average fiber length and average fiber width can be measured using an ABB Fiber Tester Plus. In this specification, the average fiber length refers to the length-weighted fiber length when all fibers of 0.0 mm or more are analyzed, and the average fiber width refers to the width-weighted fiber width. L / D is a value calculated from these measurements.

[0015] [1.3. Angle of repose (°), angle of collapse (°), angle of difference (°)] The angle of repose of powdered cellulose is usually 55.0° or less. When the angle of repose is 55.0° or less, the powder has good fluidity, and when a resin composition containing the powdered cellulose is prepared, the resin composition can maintain appropriate fluidity. The lower limit is usually 35.0° or more, but is not particularly limited.

[0016] The collapse angle of the powdered cellulose is usually 38.0° or less, preferably 36.0° or less. When the collapse angle is 38.0° or less, the powder has good fluidity when an external force is applied and the fibers are less likely to become entangled, so that a resin composition containing the powdered cellulose can maintain appropriate fluidity. The lower limit of the collapse angle is usually 20.0° or more, but is not particularly limited.

[0017] The difference angle of the powdered cellulose is preferably 10.0° or more, more preferably 13.0° or more. When the difference angle is 10.0° or more, the powder has good fluidity when an external force is applied and the fibers are less likely to become entangled, so that a resin composition containing the powdered cellulose can maintain appropriate fluidity. The upper limit of the difference angle is usually 40.0° or less, but is not particularly limited. The difference angle is expressed by the following mathematical formula (α): Difference angle = Angle of repose - Angle of collapse (α)

[0018] The angle of repose, angle of collapse and angle of difference of the present invention are measured using a powder tester (Powder Tester PT-X (manufactured by Hosokawa Micron Corporation)) on a sample whose moisture content has been adjusted to 2 to 3%.

[0019] [1.4. Intrinsic viscosity (ml / g)] The intrinsic viscosity of the powdered cellulose is preferably 380 ml / g or less, more preferably 300 ml / g or less. When the intrinsic viscosity is 380 ml / g or less, the degree of polymerization of the powdered cellulose is appropriately small, so that when a resin composition containing the powdered cellulose is prepared, the fibers are less likely to become entangled with each other, and appropriate fluidity can be maintained. The lower limit is usually 100 ml / g or more, but is not particularly limited. The intrinsic viscosity of powdered cellulose is measured, for example, using a pulp polymer viscometer RPV-1 (manufactured by PSL Rheotek) in accordance with ISO 5351:2010.

[0020] [2.1. Cellulose raw materials] The cellulose raw material is usually naturally-occurring cellulose, preferably pulp, and more preferably wood-derived pulp. Examples of wood-derived pulp include unbleached softwood kraft pulp (NUKP), bleached softwood kraft pulp (NBKP), unbleached hardwood kraft pulp (LUKP), bleached hardwood kraft pulp (LBKP), bleached softwood dissolving kraft pulp (NDKP), bleached hardwood dissolving kraft pulp (LDKP), unbleached softwood sulfite pulp (NUSP), bleached softwood sulfite pulp (NBSP), unbleached hardwood sulfite pulp ( Examples of such pulps include wood-derived pulps such as bleached hardwood sulfite pulp (LUSP), bleached softwood dissolving sulfite pulp (LBSP), bleached softwood dissolving sulfite pulp (NDSP), and bleached hardwood dissolving kraft pulp (LDSP), thermomechanical pulp (TMP), pressure groundwood pulp (PGW), refiner ground wood pulp (RGP), alkaline hydrogen peroxide mechanical pulp (APMP), and alkaline hydrogen peroxide thermomechanical pulp (APTMP).

[0021] Methods for preparing wood-derived pulp include, for example, chemical pulping (cooking). This process dissolves and removes the coloring substance lignin, and by combining this with oxygen delignification and bleaching, pulp with high brightness can be obtained. Examples of chemical pulping (cooking) processes include sulfite cooking, kraft cooking, soda-quinone cooking, and organosolv cooking. Kraft pulp is preferred from an environmental and economic perspective. Kraft cooking uses alkaline chemicals such as sodium hydroxide, potassium hydroxide, and sodium carbonate, as well as sulfur-containing chemicals such as sodium sulfide and sodium sulfite. Additives such as quinone cooking aids and polysulfides can also be used. These additives are not necessary if the wood can be cooked using alkaline chemicals alone.

[0022] In the method for preparing pulp, the pulp obtained by cooking can be subjected to oxygen delignification. The known medium-consistency or high-consistency method can be used for the oxygen delignification used in the present invention. In the medium-consistency method, the pulp consistency is preferably 8 to 15 mass%, and in the high-consistency method, it is preferably 20 to 35 mass%. As the alkali for oxygen delignification, sodium hydroxide or potassium hydroxide can be used, and as oxygen gas, oxygen from cryogenic separation, oxygen from PSA (Pressure Swing Adsorption), oxygen from VSA (Vacuum Swing Adsorption), etc. can be used. The reaction conditions for oxygen delignification are not particularly limited, but the oxygen pressure should preferably be 3 to 9 kg / cm. 2 , more preferably 4 to 7 kg / cm 2 The alkali addition rate is 0.5 to 4 mass %, the temperature is 80 to 140° C., and the treatment time is 20 to 180 minutes, and other conditions that are known in the art can be applied. In the present invention, the oxygen delignification treatment may be carried out multiple times.

[0023] The pulp that has been subjected to the oxygen delignification treatment may then be sent to a washing step, and after washing, may be subjected to a bleaching treatment as described below. The brightness of the pulp that has been subjected to the oxygen delignification treatment is preferably 30% to 55% based on ISO 2470.

[0024] Pulp preparation methods include chemical pulping (cooking) and oxygen delignification, as well as bleaching, which can produce pulp with higher brightness. Examples of bleaching methods include chlorine treatment (C), chlorine dioxide bleaching (D), alkaline extraction (E), hypochlorite bleaching (H), hydrogen peroxide bleaching (P), alkaline hydrogen peroxide treatment stage (Ep), alkaline hydrogen peroxide-oxygen treatment stage (Eop), ozone treatment (Z), chelate treatment (Q), and combinations of two or more of these treatments on pulp that has been delignified by conventional methods. Examples of combinations (sequences) of two or more treatments include DE / PD, C / DEHD, ZED-PZ / D-Ep-D, Z / D-Ep-DP, D-Ep-D, D-Ep-DP, D-Ep-PD, Z-Eop-DD, Z / D-Eop-D, and Z / D-Eop-DED (the " / " in the sequence indicates that the treatments before and after the " / " are performed consecutively without washing). The bleaching treatment is not limited to the above examples and may be any commonly used method. Pulp that has undergone bleaching treatment is usually in a fluid state (fluidized pulp).

[0025] The brightness of the pulp that has been subjected to such bleaching treatment is preferably 70% or more based on ISO 2470.

[0026] The moisture content of the cellulose raw material is usually preferably 5 to 30%, and more preferably 5 to 20%, based on 100% of the cellulose raw material. If the moisture content of the cellulose raw material is higher than the above range, the moisture content can be adjusted by a dehydration / drying treatment described below.

[0027] 3. Method for producing powdered cellulose The method for producing powdered cellulose is not particularly limited as long as it is a method for obtaining powdered cellulose from a cellulose raw material. For example, a method including at least a pulverization treatment is included, and a method including a mechanical pulverization treatment is preferred.

[0028] [Mechanical crushing treatment] Pulverization is a process in which cellulose raw materials are mechanically pulverized. Prior to pulverization, pretreatment such as dehydration and drying or acid hydrolysis may be performed, with dehydration and drying being preferred. Classification may be performed simultaneously with or after pulverization.

[0029] Examples of the pulverizer include a cutting mill, an impact mill, an airflow mill, a hammer mill, a roll mill, a roller mill, a media mill, a media stirring mill, and a freeze pulverizer, and these may be used alone or in combination of two or more.

[0030] Examples of cutting-type mills include cutting mills (manufactured by HORAI Co., Ltd.), mesh mills (manufactured by HORAI Co., Ltd.), Atoms (manufactured by Yamamoto Hyakuma Manufacturing Co., Ltd.), knife mills (manufactured by Parman Co., Ltd.), cutter mills (manufactured by Tokyo Atomizer Manufacturing Co., Ltd.), centri-cutter (Nippon Coke Engineering Co., Ltd.), rotary cutter mills (manufactured by Nara Machinery Manufacturing Co., Ltd.), turbo cutters (manufactured by Freund-Turbo Corporation), and pulp crushers (manufactured by Zuiko Co., Ltd.).

[0031] Examples of hammer mills include a hammer mill (manufactured by Hosokawa Micron Corporation), a jaw crusher (manufactured by Makino Corporation), and a hammer crusher (manufactured by Makino Sangyo Co., Ltd.).

[0032] Examples of impact mills include Pulverizer (manufactured by Hosokawa Micron Corporation), Fine Impact Mill (manufactured by Hosokawa Micron Corporation), Super Micron Mill (registered trademark, manufactured by Hosokawa Micron Corporation), Inomizer (registered trademark, manufactured by Hosokawa Micron Corporation), Fine Mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), CUM-type centrifugal mill (manufactured by Mitsui Mining Co., Ltd.), Exceed Mill (manufactured by Makino Sangyo Co., Ltd.), Ultraplex (manufactured by Makino Sangyo Co., Ltd.), Contraplex (manufactured by Makino Sangyo Co., Ltd.), Coroplex (manufactured by Makino Sangyo Co., Ltd.), Atomizer (manufactured by Seishin Enterprise Co., Ltd.), Tornado Mill (manufactured by Nikki Examples of suitable mills include: Soso Co., Ltd.), Nea Mill (Dalton Co., Ltd.), Jiyu Crusher (Nara Machinery Works Co., Ltd.), New Cosmomizer (Nara Machinery Works Co., Ltd.), Turbo Mill (Freund-Turbo Corporation), Super Powder Mill (Nishimura Machinery Works Co., Ltd.), Blade Mill (Nisshin Engineering Inc.), Super Rotor (Nisshin Engineering Inc.), Wiley Crusher (Sanki Manufacturing Co., Ltd.), Pulp Crusher (Zuiko Co., Ltd.), Jacobson Fine Pulverizer (Kobe Steel Pantech Co., Ltd.), Universal Mill (Tokuju Manufacturing Co., Ltd.), and Continuous Vibro Mill (Eurus Techno Co., Ltd.).

[0033] Examples of airflow mills include CGS-type jet mills (manufactured by Mitsui Mining Co., Ltd.), Micron Jet (registered trademark, manufactured by Hosokawa Micron Corporation), Counter Jet Mill (registered trademark, manufactured by Hosokawa Micron Corporation), Cross Jet Mill (manufactured by Kurimoto Diesel Co., Ltd.), Supersonic Jet Mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), Current Jet (manufactured by Nisshin Engineering Inc.), Jet Mill (manufactured by Sansho Industry Co., Ltd.), Selenium Mirror (manufactured by Masuko Sangyo Co., Ltd.), New Micro Sictomat (manufactured by Masuno Manufacturing Co., Ltd.), and Kryptron (manufactured by Earth Technica Corporation).

[0034] Examples of roller mills include a vertical roller mill (manufactured by Seishin Co., Ltd.), a vertical roller mill (manufactured by Sinion Co., Ltd.), a roller mill (manufactured by Kotobuki Giken Kogyo Co., Ltd.), a VX mill (Kurimoto Iron Works Co., Ltd.), a KVM-type vertical roller mill (Earth Technica Co., Ltd.), and an IS mill (IHI Plant Engineering Co., Ltd.). Of these, cutting mills and roller mills are preferred.

[0035] The conditions for the pulverization treatment can be appropriately set so as to obtain the desired powdery cellulose. For example, the treatment conditions can be adjusted by referring to a calibration curve prepared from the pulverization conditions (e.g., treatment time, input amount) and the desired physical properties of the powdery cellulose.

[0036] -Neutralization, washing, dehydration, drying treatment- The cellulose raw material is subjected to an appropriate pretreatment before being pulverized. Examples of pretreatment include neutralization, washing, deliquoring, and drying, and it is preferable to perform dehydration and drying in this order. The solids concentration of the cellulose raw material can be adjusted by the drying (dehydration) treatment, making it easy to control the physical properties of the powdered cellulose.

[0037] -Acid hydrolysis treatment- Examples of acids used in acid hydrolysis include mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid. The acid concentration is not particularly limited, but from the viewpoint of maintaining the degree of polymerization and whiteness, it is preferably lower than the acid concentration used in conventional acid hydrolysis for producing powdered cellulose, more preferably 0.1 to 2.0 N, and even more preferably 0.2 to 1.5 N. If the acid concentration is less than 0.1 N, depolymerization of cellulose by acid is suppressed, reducing the decrease in the degree of polymerization of cellulose, but micronization may become difficult. On the other hand, if the acid concentration exceeds 2.0 N, depolymerization of cellulose progresses, facilitating micronization, improving powder fluidity, but reducing the degree of polymerization may result in a decrease in tablet hardness (making tablets more likely to disintegrate when molded). The reaction conditions for acid hydrolysis are not particularly limited, but the reaction temperature is typically 80 to 100°C, and the reaction time is typically 30 minutes to 3 hours.

[0038] Prior to the acid hydrolysis treatment, the cellulose raw material may be pretreated. Examples include slurrying the cellulose raw material (preparing a dispersion) and adjusting the concentration of the cellulose raw material. The concentration of the cellulose raw material is typically 3 to 10% by weight (solids content equivalent) relative to the dispersion. When the cellulose raw material is fluidized pulp that has been bleached, a treatment to increase the pulp concentration is usually performed before hydrolysis. A dehydrator such as a screw press or belt filter may be used to adjust (concentrate) the concentration of the cellulose raw material. The acid hydrolysis treatment may be performed on a slurry of the cellulose raw material, or on a sheet of the cellulose raw material. When the cellulose raw material is a dry pulp sheet, the pulp is usually loosened before the acid hydrolysis treatment. A crusher such as a roll crusher may be used to loosen the pulp.

[0039] During the pulverization treatment after acid hydrolysis, at least one other component (e.g., organic component, inorganic component) may be optionally added to the pulverization treatment together with the acid hydrolysis product. This can impart functionality to the powdered cellulose or improve its functionality. The amount of the other component to be added may be appropriately selected. Furthermore, prior to the pulverization step, the acid hydrolysis product may be further subjected to the above-mentioned neutralization, washing, dehydration, and drying treatments.

[0040] The powdered cellulose may be chemically treated as needed. The chemical treatment is preferably a treatment that does not significantly impair the degree of polymerization of the cellulose raw material. The chemical treatment may be carried out when the cellulose raw material is subjected to a pulverization treatment, or may be carried out before a pretreatment for the pulverization treatment.

[0041] [4. Uses of powdered cellulose] Other uses of powdered cellulose include, for example, industrial additives (for resins such as polypropylene, phenolic resins, and melamine resins, and for various rubbers), and as a component or raw material for resin compositions (for example, polyolefin resins, modified polyolefin resins, and rubbers), rubber compositions (for example, automobiles, personal computers, building materials, and containers), and the like.

[0042] The powdered cellulose of the present invention can be used particularly as a molding resin material. By using the powdered cellulose of the present invention as a molding resin material, the flowability of the resin composition can be improved, and the dispersibility of the powdered cellulose in the resin can be improved, making it easier to obtain the desired mechanical strength.

[0043] When the powdered cellulose of the present invention is used as a molding resin material, the powdered cellulose content can be 10% by weight or more when the molding resin material is taken as 100% by weight, although there are no particular limitations. Furthermore, because the molding resin material has good fluidity due to the effects of the present invention, the powdered cellulose content can be 20% by weight or more, 50% by weight or more, or 60% by weight or more. [Example]

[0044] The present invention will be described below with reference to examples. The following examples do not limit the present invention. Test methods used in the examples of the present application are as follows. The methods for measuring physical properties and the like are the same as those described above unless otherwise specified.

[0045] <Particle size D.50> A laser diffraction particle size distribution analyzer (Mastersizer 3000, Malvern Panalytical Division, Spectris) was used. The particle size distribution was measured by wet measurement (with ultrasonic irradiation) using the laser scattering method as the measurement principle. When the particle size distribution is expressed as a volume accumulation distribution, the value at which the integrated value of the volume accumulation distribution is 50% was defined as the particle diameter D.50.

[0046] Wet measurements were performed by adding the sample to the measurement section in water stirred at 3000 rpm so that the scattering intensity was about 10%. When irradiating with ultrasound, the sample in water was irradiated with ultrasound under the following conditions before wet measurements were performed. Mode: Continuous ·Strength: 100% Time: 600 seconds

[0047] The particle size distribution analysis was carried out under the following conditions for all measurement conditions. Analysis: General Analysis Sensitivity: Emphasis Light scattering model: Mie theory

[0048] <Average fiber length (μm), average fiber width (μm), L / D (aspect ratio)> The average fiber length and average fiber width of the raw pulp and powdered cellulose were measured using an L&W Fiber Tester Plus (manufactured by ABB) according to the following procedure. 0.1 g of sample was placed in a cylinder containing 200 ml of pure water, stirred for approximately 1 minute, and then transferred to a dedicated 300 ml beaker. The sample was then placed in a sample cycler and measurement initiated. Measurements were continued until at least 55,000 fibers with a fiber length of 0.1 mm or greater were counted. The length-weighted average fiber length and width-weighted average fiber width were calculated, and these were used as the average fiber length and average fiber width of the sample. The measurement was performed after setting the Fines Limit Max value to 0.0 and the Length class 1 Min value to 0.001 on the Sample type screen, which defines the measurement conditions. The L / D (aspect ratio) was calculated by dividing the average fiber length by the average fiber width.

[0049] <Angle of repose (°), angle of collapse (°), angle of difference (°)> Using a powder tester (model number: PT-X, manufactured by Hosokawa Micron Corporation), powdered cellulose was measured by the following method. ·Angle of repose An appropriate amount of sample with moisture content adjusted to 2-3% was placed on a sieve with 710μm openings and vibrated (vibration conditions: width 1.5mm, vibration time 180 seconds, slowdown 10 seconds), and the sample was dropped and piled up through the holes in a funnel set at the bottom of the sieve onto a horizontal plate of a certain area until it formed a uniform shape, forming a conical mound. The Angle Repose of this mound was taken as the angle of repose of the sample. Collapse angle In the angle of repose test, a conical mound was formed on a horizontal plate, and then a weight of a certain weight placed on the same base as the horizontal plate was dropped to give a certain impact to the powder. After some of the powder flowed naturally and fell off the horizontal plate, the collapse angle of the remaining conical mound was determined as the angle of elevation from a point on the outer periphery of the base to the apex of the cone. ·Difference angle The difference between the angle of repose and the angle of collapse was defined as the angle of difference.

[0050] <Thermogravimetric reduction rate> The thermal weight loss rate of powdered cellulose was measured by heating the powdered cellulose from 35°C to 550°C at a rate of 20°C / min in a nitrogen atmosphere using a thermal analyzer (TGA Q50, TA Instruments Japan Co., Ltd.). The weights were measured at 110°C and 300°C, and the rate of change was calculated as the thermal weight loss rate (%). 5–15 mg of powdered cellulose was weighed onto a platinum pan and the measurement was performed. Thermal weight loss rate (%) = 100 × (weight at 1-300°C / weight at 110°C)

[0051] <Intrinsic viscosity> The intrinsic viscosity of powdered cellulose was measured using a pulp polymer viscometer RPV-1 (PSL Rheotek) in accordance with ISO 5351:2010.

[0052] The tensile modulus, flexural modulus, Charpy impact strength, flowability (MFR), and dispersibility of Examples 1 to 5 and Comparative Examples 1 and 2 were evaluated by the following methods.

[0053] <Preparation of Resin Composition and Test Piece> Powdered cellulose, polypropylene resin (BC10HRF, manufactured by Japan Polypropylene Corporation), and maleic anhydride-modified polypropylene (UMEX 1010, manufactured by Sanyo Chemical Industries, Ltd.) were weighed out in a 51:48.5:0.5 ratio to make a total of 8 g, and eight batches were prepared. Each 8 g batch was placed in a small kneader ("MC15," manufactured by Xplore Instruments) and kneaded at 200 °C for 5 minutes. Five dumbbell-shaped test specimens (Type A12, JIS K7139) and eight rectangular test specimens (Type B1, JIS K7139) were molded in an Xplore injection molding machine (manufactured by Xplore Instruments) at a cylinder temperature of 200 °C and a mold temperature of 40 °C. Similarly, 25 g of the resin composition was kneaded in the small kneader for 5 minutes at 200 °C and collected for MFR measurement.

[0054] <Tensile strength (MPa)> The obtained dumbbell-shaped test pieces were subjected to tensile stress measurement using a precision universal testing machine (Shimadzu Corporation, "Autograph AG-Xplus") in accordance with JIS K 7161: Plastics - Testing Method for Tensile Properties, at a test speed of 1 mm / min and an initial gauge length of 30 mm, and the maximum value was recorded as the tensile strength. The average value of the tensile strengths of the five test pieces was recorded as the tensile strength of the sample. The tensile strength of the resin (BC10HRF) alone was 19.2 MPa.

[0055] <Flexural strength (MPa)> The obtained rectangular test pieces were subjected to a bending test in accordance with JIK 7171 using a precision universal testing machine (Shimadzu Corporation's "Autograph AG-Xplus") with a support distance of 64 mm and a test speed of 10 mm / min. The maximum bending stress that the test piece could withstand during the bending test was recorded as the bending strength. The average value of the bending strengths of the three test pieces was recorded as the bending strength of the sample. The bending strength of the resin (BC10HRF) alone was 28.5 MPa.

[0056] <Charpy impact strength (kJ / m 2 )> A Charpy impact test was carried out on the obtained rectangular test pieces using a Charpy impact tester (model: IT, manufactured by Toyo Seiki Seisakusho, Ltd.). A notch 2 mm deep was inserted in the center of the test piece. A JC005J (0.5J) pendulum was used to strike the side opposite the notch, and the impact strength was calculated. The average value of the Charpy impact strengths of the five test pieces was taken as the Charpy impact strength of the sample.

[0057] <MFR(g / 10min)> The melt flow rate (MFR) of the resulting resin composition was measured using a melt flow indexer (G-02, manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with JIS K7210 at a measurement temperature of 230°C and a test load of 2.16 kg.

[0058] <Dispersibility> The cellulose aggregates in the strip-shaped test pieces were visually confirmed and evaluated under the following conditions. ◎: Fewer than 10 small (≦1 mm) aggregates and no large (>1 mm) aggregates were observed ○: 10-19 small (≦1 mm) agglomerates and / or 1-4 large (>1 mm) agglomerates were observed △: 20 or more small (≦1 mm) agglomerates and / or 5 or more large (>1 mm) agglomerates can be identified

[0059] <Preparation of powdered cellulose> Example 1 Bleached hardwood kraft pulp (LBKP, Nippon Paper Industries Co., Ltd.) was used as the raw material. The pulp slurry was acid hydrolyzed at 90°C for 40 minutes with 1.2N hydrochloric acid to a concentration of 5%, neutralized, washed, and then dried. The pulp was then pulverized in a sample mill (Tokyo Atomizer Manufacturing Co., Ltd., TASM-1, mesh: φ0.3 mm) to obtain powdered cellulose 1.

[0060] Example 2 Powdered cellulose 2 was obtained in the same manner as in Example 1, except that the concentration of hydrochloric acid during acid hydrolysis was 0.3N.

[0061] Example 3 Powdered cellulose 3 was obtained in the same manner as in Example 1, except that hardwood bleached dissolved sulfite pulp (LDSP, brand: LDPT, manufactured by Nippon Paper Industries Co., Ltd.) was used as the raw material.

[0062] Example 4 Dry sheets of bleached hardwood dissolved sulfite pulp (LDSP, brand: LDPT, manufactured by Nippon Paper Industries Co., Ltd.) were used as raw materials. The sheets were coarsely crushed in a uniaxial crusher, and then powdered in a vertical roller mill (Hatsuratsu Co., Ltd.) at a feed rate of 41 kg / h, a classifier frequency of 28 Hz, and a crushing roller frequency of 55 Hz to obtain powdered cellulose 4.

[0063] Example 5 Dry sheets of bleached softwood kraft pulp (NBKP, manufactured by Nippon Paper Industries Co., Ltd.) were used as raw materials. The sheets were coarsely crushed in a uniaxial crusher, and then subjected to primary crushing in a vertical roller mill (Hatsuratsu Co., Ltd.) at a feed rate of 32 kg / h, a classifier frequency of 15 Hz, and a crushing roller frequency of 55 Hz. The resulting material was then subjected to secondary crushing in the same equipment at a feed rate of 40 kg / h, a classifier frequency of 40 Hz, and a crushing roller frequency of 55 Hz, to obtain powdered cellulose 5.

[0064] (Comparative Example 1) Dry sheets of bleached hardwood dissolved sulfite pulp (LDSP, brand: LDPT, manufactured by Nippon Paper Industries Co., Ltd.) were used as raw materials and were coarsely pulverized using a cutting mill (PI-20120, manufactured by Horai Co., Ltd., screen diameter Φ3 mm), and then pulverized using a cutting mill (HA8-2542, manufactured by Horai Co., Ltd., main mesh: 165 mesh, auxiliary mesh: 20 mesh) to obtain powdered cellulose 6.

[0065] (Comparative Example 2) Powdered cellulose 7 was obtained in the same manner as in Comparative Example 1, except that a dry sheet of bleached hardwood kraft pulp (LBKP, manufactured by Nippon Paper Industries Co., Ltd.) was used as the raw material.

[0066] [Table 1]

[0067] Examples 1 to 5, in which the angle of repose and the angle of collapse were within the predetermined ranges, had better fluidity (MFR) and dispersibility when made into a resin composition than Comparative Examples 1 and 2.

Claims

1. A powdered cellulose for use in molding resin materials, having a particle diameter D50 of 10 to 100 μm, an angle of repose of 55° or less, and a collapse angle of 38° or less.

2. 2. The powdery cellulose for use in molding resin materials according to claim 1, wherein the difference angle between the angle of repose and the angle of collapse is 10 to 30 degrees.

3. 2. The powdery cellulose for use in molding resin materials according to claim 1, having an aspect ratio of 1.0 to 6.

0.

4. 2. The powdered cellulose for use in molding resin materials according to claim 1, having an intrinsic viscosity of 380 ml / g or less.

5. A method for producing powdered cellulose for use in molding resin materials, which has a particle diameter D50 of 10 to 100 μm, an angle of repose of 55° or less, and a collapse angle of 38° or less, characterized in that the method includes an acid hydrolysis step during the pulverization of the cellulose raw material.

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