Powdery cellulose

Abstract

To provide a powdery cellulose which enhances tensile strength and flexural strength when formulated into a resin composition, and also exhibits superior impact strength.SOLUTION: The present invention provides a powdery cellulose for a molding resin material, the powdery cellulose having a particle diameter D50 of 10-100 μm and an aspect ratio of 4.0-10.0, and the raw pulp for the powdery cellulose being a hardwood bleached kraft pulp (LBKP) containing 25% or more of acacia-derived pulp.SELECTED DRAWING: None

Description

Technical Field

[0001] The present invention relates to powdered cellulose.

Background Art

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

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] As one of the uses of a resin composition containing powdered cellulose, it is used for exterior parts such as home appliance housings and automotive interior and exterior parts. The properties required for exterior parts include mechanical strengths such as tensile strength, flexural strength, and impact strength. However, a resin composition containing general cellulose fibers has a problem that although its tensile strength and flexural strength are improved compared to the resin alone, its impact strength decreases.

[0005] The present invention has been made in view of the above, and an object thereof is to provide a powdered cellulose that improves tensile strength and flexural strength and has good impact strength when used as a resin composition.

Means for Solving the Problems

[0006] The present invention provides the following [1] to [5]. 〔1〕Powdery cellulose for a molding resin material having a particle diameter D50 of 10 to 100 μm and an aspect ratio of 4.0 to 10.0, wherein the raw material pulp of the powdery cellulose is hardwood bleached kraft pulp (LBKP) containing 25% or more of acacia-derived pulp. 〔2〕Powdery cellulose for a molding resin material according to 〔1〕, wherein the average fiber length measured by a fiber tester plus of the powdery cellulose is 140 to 200 μm. 〔3〕Powdery cellulose for a molding resin material according to 〔1〕, wherein the value obtained by subtracting the particle diameter D50 from the particle diameter D90 of the powdery cellulose (particle diameter D90 - particle diameter D50) is 80 to 140 μm. 〔4〕A molding resin material comprising the powdery cellulose and a thermoplastic resin. 〔5〕The molding resin material according to 〔4〕, wherein the content of the powdery cellulose is 10% by weight or more when the molding resin material is 100% by weight.

Advantages of the Invention

[0007] According to the present invention, it is possible to provide powdery cellulose that improves tensile strength and flexural strength and has good Charpy impact strength when used as a resin composition.

Embodiments for Carrying Out the Invention

[0008] 〔1. Powdery cellulose〕 The powdery cellulose has a predetermined average particle diameter and aspect ratio, and the raw material pulp is hardwood bleached kraft pulp (LBKP) containing 25% or more of acacia-derived pulp.

[0009] 〔1.1. Average particle diameter〕 〔Particle size distribution〕 The particle size distribution of powdered cellulose can be expressed as the particle size distribution (10% diameter, 50% diameter, 90% diameter, i.e., D.10, D.50, D.90, respectively) when the integrated value of the volume accumulation distribution is 10%, 50%, and 90%. In this specification, the particle size distribution is a value obtained by wet measurement (with ultrasonic irradiation) using the laser scattering method as the measurement principle. Note that the average particle size in this specification refers to the value of D.50 obtained by wet measurement (with ultrasonic irradiation).

[0010] -Wet measurement (with ultrasonic irradiation)- In this specification, the wet condition (with ultrasonic irradiation) refers to the condition where the particle size is measured after ultrasonic irradiation is performed on the sample after adding water. The preferred ranges of D.10, D.50, and D.90 in the case of wet (with ultrasonic) are as follows. Generally, the larger the particle size, the higher the tendency for fibers to entangle with each other. Furthermore, within the following ranges, the strength can be appropriately improved without impairing their properties when added to resins, rubbers, etc. D.10 is usually 3.0 μm or more, preferably 5.0 μm or more, and more preferably 10.0 μm or more. The upper limit is usually 20.0 μm or less, preferably 17.0 or less, and more preferably 15.0 μm or less. D.50 is usually 10.0 μm or more, preferably 20.0 μm or more, more preferably 30.0 μm or more, and even more preferably 35.0 μm or more (however, it is a value larger than D.10). The upper limit is usually 100.0 μm or less, preferably 80.0 μm or less, more preferably 60.0 μm or less, and even more preferably 50.0 μm or less. D.90 is usually 80.0 μm or more, preferably 100.0 μm or more, and more preferably 120.0 μm or more (however, it is a value larger than D.50). The upper limit is usually 200.0 μm or less, preferably 180.0 μm or less, and more preferably 160.0 μm or less.

[0011] The value obtained by subtracting the particle size D10 from the particle size D90 of the powdery cellulose of the present invention (particle size D90 - particle size D10) is preferably 100 to 150 μm, more preferably 110 to 140 μm, and even more preferably 120 to 140 μm. When the particle size D90 - particle size D10 is 100 to 150 μm, the particle size distribution is appropriate, so the strength can be improved when kneaded with a resin.

[0012] Also, the value obtained by subtracting the particle size D50 from the particle size D90 of the powdery cellulose of the present invention (particle size D90 - particle size D50) is preferably 80 to 140 μm, more preferably 90 to 130 μm, and even more preferably 100 to 120 μm. When the particle size D90 - particle size D50 is 80 to 140 μm, moderately large-sized powder is contained, so the strength can be improved when kneaded with a resin.

[0013] Also, the value obtained by subtracting the particle size D10 from the particle size D50 of the powdery cellulose of the present invention (particle size D50 - particle size D10) is preferably 10 to 40 μm, more preferably 15 to 30 μm, and even more preferably 20 to 30 μm. When the particle size D50 - particle size D10 is 10 to 40 μm, moderately small-sized powder is contained, so the strength can be improved when kneaded with a resin.

[0014] [1.2. Average fiber width (μm), average fiber length (μm), average fiber length / average fiber width (L / D, aspect ratio)] The average fiber length is preferably 140 to 200 μm, more preferably 150 to 190 μm. When the average fiber length is 140 to 200 μm, the tensile strength and flexural strength can be improved when kneaded with a resin, and the impact strength is less likely to decrease.

[0015] The average fiber width is usually 10 μm or more, preferably 15 μm or more, more preferably 20 μm or more. The upper limit is usually 50 μm or less, preferably 40 μm or less, more preferably 35 μm or less.

[0016] The average fiber length / average fiber width (L / D, aspect ratio) of the powdery cellulose is preferably 4.0 to 10.0, more preferably 4.0 to 8.0, and still more preferably 6.0 to 8.0. When a filler is added to a resin, the impact resistance generally decreases. However, when the L / D of the powdery cellulose is 4.0 to 10.0, the number of fiber ends that become the starting points of fracture in the resin composition containing the powdery cellulose is smaller than that of fillers with a low L / D. Therefore, a significant decrease in impact resistance is less likely to occur, and the fluidity of the resin composition can also be ensured.

[0017] The average fiber length and average fiber width can be measured with a Fiber Tester Plus manufactured by ABB. In this specification, the average fiber length refers to the length-weighted fiber length when all fibers of 0.0 mm or more are taken as the analysis targets, and the average fiber width refers to the width-weighted fiber width. L / D is a value calculated from these measured values.

[0018] 〔1.3. Angle of repose (°), bulk specific gravity (g / cc)〕 The angle of repose of the powdery cellulose is preferably 40° to 60°, more preferably 47° to 56°, and still more preferably 50° to 53°. When the angle of repose exceeds 60°, the powder fluidity deteriorates, resulting in poor workability. When the angle of repose is less than 40°, the falling speed of the powder increases, but powder scattering occurs, resulting in poor workability.

[0019] The angle of repose of the present invention can be measured by the following method using a Powder Tester (model number: PT-X, manufactured by Hosokawa Micron Corporation). An appropriate amount of a sample with the moisture adjusted to 2 to 3% is placed on a sieve with an opening of 710 μm and vibrated (vibration conditions: amplitude 1.5 mm, vibration time 180 seconds, slowdown 10 seconds), and it is allowed to fall and deposit on a horizontal plate of a certain area through the hole of a funnel set below the sieve until it forms a certain shape, forming a conical pile. The value of the Angle Repose (elevation angle) of this pile is taken as the angle of repose of the sample.

[0020] The apparent specific gravity of the powdery cellulose is preferably 0.1 to 0.6 g / cc, more preferably 0.18 to 0.5 g / cc, and even more preferably 0.22 to 0.3 g / cc. When the apparent specific gravity is 0.1 to 0.6 g / cc, the workability is excellent, and the tensile strength and flexural strength are improved when kneaded with the resin.

[0021] The apparent specific gravity can be measured by the following method. Weigh 10 g of the sample with an upper pan balance and put it into a 100 ml graduated cylinder using a funnel. Strike the bottom of the cylinder on a tabletop covered with a rubber sheet and continue until the height of the sample no longer decreases. Level the sample in the cylinder, read the scale, and obtain the volume. Then, calculate the apparent specific gravity using the following formula. Apparent specific gravity = 10 (g) / volume (cc)

[0022] 〔2. Cellulose raw material〕 The cellulose raw material is usually natural-derived cellulose, and hardwood pulp is preferred. Examples of the hardwood used include acacia, eucalyptus, beech, cinnamon, birch, poplar, oak, kunugi, etc. However, since the fibers are relatively thin and the aspect ratio tends to be high when pulverized to a certain particle size, it is preferable to contain 25% or more of pulp derived from acacia.

[0023] As a method for preparing pulp derived from broad-leaved trees containing acacia, for example, a method including treatment by a chemical pulping method (kraft pulping method) can be mentioned. By the treatment by the chemical pulping method (kraft pulping method), lignin, which is a coloring substance, is dissolved and removed, and pulp with a high whiteness can be obtained by combining it with oxygen delignification treatment and bleaching treatment. Examples of the chemical pulping method (kraft pulping method) include the sulfite kraft pulping method, the kraft pulping method, the soda-quinone kraft pulping method, and the organosolv kraft pulping method. However, as the kraft pulping method used in the present invention, kraft pulp is preferable. The kraft pulping method is a method in which alkaline chemicals such as sodium hydroxide, potassium hydroxide, and sodium carbonate and chemicals containing sulfur such as sodium sulfide and sodium sulfite are used in combination, and quinone-based cooking aids, polysulfides, etc. can be used as additives. These additives do not need to be used if the pulp can be cooked with only alkaline chemicals.

[0024] Examples of broad-leaved tree kraft pulp include unbleached broad-leaved tree kraft pulp (LUKP) and bleached broad-leaved tree kraft pulp (LBKP). Bleached broad-leaved tree kraft pulp (LBKP) is preferable in that it causes less coloring when used in the resin composition.

[0025] In the method for preparing pulp, oxygen delignification treatment can be performed on the pulp obtained by cooking. As the oxygen delignification used in the present invention, known medium consistency method or high consistency method can be applied as it is. In the case of the medium consistency method, it is preferably carried out at a pulp concentration of 8 to 15% by mass, and in the case of the high consistency method, it is preferably carried out at 20 to 35% by mass. As the alkali in oxygen delignification, sodium hydroxide and potassium hydroxide can be used, and as the oxygen gas, oxygen from cryogenic separation method, oxygen from PSA (Pressure Swing Adsorption), oxygen from VSA (Vacuum Swing Adsorption), etc. can be used. The reaction conditions of the oxygen delignification treatment are not particularly limited, but the oxygen pressure is 3 to 9 kg / cm 2 , more preferably 4 to 7 kg / cm 2The alkali addition rate is 0.5 to 4 mass %, the temperature is 80 to 140° C., 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.

[0026] 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.

[0027] In the preparation of pulp, in addition to chemical pulping (cooking) and oxygen delignification, a bleaching treatment can also be carried out. This results in a pulp with a higher brightness. Examples of bleaching treatment 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 any conventional method. 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 means 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 a commonly used method. Pulp that has been bleached is usually in a fluid state (fluid pulp).

[0028] The brightness of the pulp subjected to such bleaching treatment is preferably 70% or more based on ISO 2470.

[0029] The moisture content of the cellulose raw material is usually preferably 5 to 30%, preferably 5 to 20% based on 100% of the cellulose raw material. When the moisture content of the cellulose raw material is more than the above-mentioned range, the moisture content may be adjusted by the dehydration and drying treatment described below.

[0030] 〔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 can be mentioned, and a method including a mechanical pulverization treatment is preferable.

[0031] 〔Mechanical pulverization treatment〕 The pulverization treatment is a treatment for mechanically pulverizing the cellulose raw material. Prior to the pulverization treatment, pretreatment such as dehydration and drying treatment, acid hydrolysis treatment, etc. may be performed, and dehydration and drying treatment is preferable. Classification treatment may be performed simultaneously with or after the pulverization treatment.

[0032] Examples of the pulverizer include a cutting mill, an impact mill, a pneumatic mill, a hammer mill, a roll mill, a roller mill, a media mill, a media stirring mill, and a freeze pulverizer, and they may be used alone or in combination of two or more.

[0033] Examples of the cutting mill include a cutting mill (manufactured by Horai Co., Ltd.), a mesh mill (manufactured by Horai Co., Ltd.), Atoms (manufactured by Yamamoto Hyakuba Seisakusho Co., Ltd.), a knife mill (manufactured by Palman), a cutter mill (manufactured by Tokyo Atomizer Co., Ltd.), a centric cutter (manufactured by Nippon Coke Industry Co., Ltd.), a rotary cutter mill (manufactured by Nara Machinery Co., Ltd.), a turbo cutter (manufactured by Floyd Turbo Co., Ltd.), and a pulp crusher (manufactured by Zuiho Co., Ltd.).

[0034] Examples of the hammer mill include a hammill (manufactured by Hosokawa Micron Corporation), a jaw crusher (manufactured by Makino Co., Ltd.), and a hammer crusher (manufactured by Makeno Sangyo Co., Ltd.).

[0035] Examples of impact mills include, for example, 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.), IXeed Mill (manufactured by Makino Sangyo Co., Ltd.), Ultra Plex (manufactured by Makino Sangyo Co., Ltd.), Contra Plex (manufactured by Makino Sangyo Co., Ltd.), Colo Plex (manufactured by Makino Sangyo Co., Ltd.), Atomizer (manufactured by Seishin Enterprise Co., Ltd.), Tornado Mill (manufactured by Nikkiso Co., Ltd.), Near Mill (manufactured by Dalton Co., Ltd.), Free Mill (manufactured by Nara Machinery Co., Ltd.), New Cosmomizer (manufactured by Nara Machinery Co., Ltd.), Turbo Mill (manufactured by Floyd Turbo Co., Ltd.), Super Powder Mill (manufactured by Nishimura Machinery Co., Ltd.), Blade Mill (manufactured by Nisshin Engineering Co., Ltd.), Super Rotor (manufactured by Nisshin Engineering Co., Ltd.), Wiley Mill (manufactured by Sanki Seisakusho Co., Ltd.), Pulp Mill (manufactured by Zuiho Seisakusho Co., Ltd.), Jacobson Fine Mill (manufactured by Kobe Steel Pantech Co., Ltd.), Universal Mill (manufactured by Tokuju Kousakusho Co., Ltd.), Continuous Vibro Mill (manufactured by Eurastech Co., Ltd.).

[0036] Examples of air-classifying mills include, for example, CGS type jet mill (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 Iron Works Co., Ltd.), Supersonic Jet Mill (manufactured by Nippon Pneumatic Mfg. Co., Ltd.), Current Jet (manufactured by Nisshin Engineering Co., Ltd.), Jet Mill (manufactured by Mitsou Ind. Co., Ltd.), Selen Mirror (manufactured by Masayuki Sangyo Co., Ltd.), New Micro Cyclotmat (manufactured by Masano Seisakusho Co., Ltd.), Crypton (manufactured by Earth Technica Co., Ltd.).

[0037] Examples of roller mills include vertical roller mills (manufactured by Seishin Co., Ltd.), vertical roller mills (manufactured by Shinion Co., Ltd.), roller mills (manufactured by Kotobuki Giken Kogyo Co., Ltd.), VX mills (manufactured by Kurimoto Iron Works, Ltd.), KVM vertical roller mills (manufactured by Earth Technica Co., Ltd.), and IS mills (manufactured by IHI Plant Engineering Co., Ltd.). Among these, cutting mills and roller mills are preferred.

[0038] The conditions for the pulverization treatment can be appropriately set so as to obtain the desired powdered cellulose. For example, the treatment conditions can be adjusted by referring to a calibration curve created from the pulverization conditions (e.g., treatment time, input amount) and the desired physical properties of the powdered cellulose.

[0039] - Neutralization, washing, dehydration, and drying treatment - The cellulose raw material is appropriately pretreated before the pulverization treatment. Examples of the pretreatment include neutralization, washing, liquid removal, and drying treatment, and it is preferable to perform the dehydration and drying treatments in this order. The cellulose raw material can adjust the solid content concentration by the drying (dehydration) treatment, and it is easy to control the physical property values of the powdered cellulose. The solid content concentration is usually adjusted to 15% or more, preferably 20% or more.

[0040] - Acid hydrolysis treatment - Examples of the acid used for the acid hydrolysis treatment include mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid. The acid concentration is not particularly limited, but from the viewpoints of maintaining the degree of polymerization and whiteness, it is preferably lower than the acid concentration in the conventional acid hydrolysis treatment for manufacturing powdered cellulose, more preferably 0.4 - 2.0 N, and even more preferably 0.5 - 1.5 N. When the acid concentration is less than 0.4 N, the depolymerization of cellulose by the acid is suppressed, and a reduction in the degree of polymerization of cellulose can be reduced, but it may be difficult to achieve fine particle size. On the other hand, when it exceeds 2.0 N, the depolymerization of cellulose progresses and fine particle size becomes easy, so the powder fluidity is improved, but the tablet hardness may decrease with the decrease in the degree of polymerization (when formed, it may be prone to disintegration). The reaction conditions for the acid hydrolysis treatment are not particularly limited, but the reaction temperature is usually 80 - 100°C, and the reaction time is usually 30 minutes - 3 hours.

[0041] Prior to the acid hydrolysis treatment, pretreatment may be performed on the cellulose raw material. For example, slurrying of the cellulose raw material (preparation of a dispersion) and adjustment of the cellulose raw material concentration can be mentioned. The concentration of the cellulose raw material is usually 3 to 10% by weight (in terms of solid content) with respect to the dispersion. When the cellulose raw material is a bleached fluid pulp, usually, a treatment to increase the pulp concentration is often performed before hydrolysis. For the adjustment (concentration) of the cellulose raw material concentration, a dehydrator such as a screw press or a belt filter may be used. The acid hydrolysis treatment may be performed on the slurry of the cellulose raw material, or may be performed on the sheet-like cellulose raw material. When the cellulose raw material is a dry sheet of pulp, usually, the pulp is loosened and then the acid hydrolysis treatment is performed. When loosening the pulp, a crusher such as a roll crusher may be used.

[0042] During the pulverization treatment after acid hydrolysis, if necessary, at least one other component (for example, an organic component, an inorganic component) may be subjected to the pulverization treatment together with the acid hydrolysis product. Thereby, functionality can be imparted to or the functionality can be improved in the powdered cellulose. The blending amount of the other component may be appropriately selected as an appropriate amount. Further, prior to the pulverization step, the above-mentioned neutralization, washing, dehydration, and drying treatments may be further performed on the acid hydrolysis product.

[0043] The powdered cellulose may be subjected to a chemical treatment if necessary. The chemical treatment is preferably a treatment that does not significantly impair the degree of polymerization of the cellulose raw material. The timing of the chemical treatment may be performed during the pulverization treatment of the cellulose raw material, or may be performed before the pretreatment of the pulverization treatment.

[0044] 〔4. Uses of Powdered Cellulose〕 As uses of other powdered celluloses, for example, they can be used as industrial additives (for example, for resins such as polypropylene, phenolic resin, and melamine resin, and for various rubbers). Also, they can be used as components and raw materials of resin compositions (for example, polyolefin resins, modified polyolefin resins, rubbers), rubber compositions (for example, automobiles, personal computers, building materials, containers), etc.

[0045] The powdery cellulose of the present invention can be used particularly as a resin material for molding. By using the powdery cellulose of the present invention in a resin material for molding, the tensile strength and flexural strength are improved.

[0046] When the powdery cellulose of the present invention is used for a resin material for molding, although there is no particular limitation, the content of the powdery cellulose can be 10% by weight or more, and further can be 20% by weight or more, 50% by weight or more when the resin material for molding is 100% by weight.

Examples

[0047] Hereinafter, the present invention will be described with reference to examples. The following examples do not limit the present invention. The test methods in the examples of the present application are shown below. In addition, the measurement method of physical property values and the like is the measurement method described above unless otherwise specified.

[0048] <Average particle size> A laser diffraction particle size distribution analyzer (MasterSizer 3000, Malvern Panalytical Limited, Malvern, UK) was used. Using the laser scattering method as the measurement principle, the particle size distribution was measured by wet measurement (with ultrasonic irradiation). When the particle size distribution was expressed as a volume accumulation distribution, the values at which the integrated values of the volume accumulation distribution were 10%, 50%, and 90% were defined as the particle size distribution D.10, D.50, and D.90, respectively. The D.50 of wet (with ultrasonic irradiation) was defined as the average particle size.

[0049] For the wet measurement, the sample was added to the measurement part in water being stirred at 3000 rpm so that the scattering intensity became about 10%. When ultrasonic waves were irradiated, ultrasonic waves were applied to the sample in water based on the following conditions and then the wet measurement was performed. · Mode: Continuous · Intensity: 100% · Time: 600 seconds

[0050] The analysis of the particle size distribution was performed under the following conditions in any measurement conditions. · Analysis: General-purpose · Analysis sensitivity: Emphasized · Light scattering model: Mie theory

[0051] <Average fiber length (μm), average fiber width (μm), L / D (aspect ratio)> Measurement was carried out using an L&W Fiber Tester Plus (manufactured by ABB) according to the following procedure. 0.1 g of the sample was placed in a cylinder containing 200 ml of pure water, stirred for about 1 minute, then transferred to a dedicated 300 ml beaker, set in a sample cycler, and measurement was started. Measurement was performed until more than 55,000 fibers with a fiber length of 0.1 mm or more were counted. The length-weighted fiber length and width-weighted fiber width were obtained and used as the average fiber length and average fiber width of the powdered cellulose. In addition, on the Sample type screen for determining the measurement conditions, the Max value of Fines Limit was set to 0.0 and the Min value of Length class1 was set to 0.001 before measurement. The obtained average fiber length was divided by the average fiber width to calculate the L / D (aspect ratio).

[0052] <Angle of repose (°)> Measurement was carried out using a Powder Tester (model number: PT-X, manufactured by Hosokawa Micron Corporation) by the following method. An appropriate amount of the sample with the moisture adjusted to 2 - 3% was placed on a sieve with an opening of 710 μm and vibrated (vibration conditions: amplitude 1.5 mm, vibration time 180 seconds, slowdown 10 seconds), and it was allowed to fall and deposit onto a horizontal plate of a certain area through the hole of a funnel set at the bottom of the sieve until it formed a certain shape, forming a conical pile. The value of the Angle Repose (elevation angle) of this pile was taken as the angle of repose of the sample.

[0053] <Apparent specific gravity (g / cc)> Weigh 10 g of the sample using an upper pan balance and place it in a 100-ml graduated cylinder using a funnel. Strike the bottom of the cylinder on a tabletop covered with a rubber sheet and continue until the height of the sample no longer decreases. Level the sample in the cylinder, read the scale, and determine the volume. Then, calculate the apparent specific gravity using the following formula. Apparent specific gravity = 10 (g) / volume (cc)

[0054] <(Moisture content (%))> The moisture in the powdered cellulose was measured using 1 g of the sample with an infrared moisture meter (FD-720 type, manufactured by Kett Scientific Laboratory Co., Ltd., at 105 °C).

[0055] For the tensile strength, flexural strength, and Charpy impact strength of Examples 1 to 3 and Comparative Examples 1 to 5, evaluation was carried out by the following method.

[0056] <Preparation of resin composition and test pieces> Powdered cellulose, polypropylene resin (BC10HRF, manufactured by Nippon Polypropylene Co., Ltd.), and maleic anhydride-modified polypropylene (Yumex 1010, manufactured by Sanyo Chemical Industries, Ltd.) were weighed in a ratio of 51:48.5:0.5 to a total of 8 g, and this was prepared 8 times. Weigh 8 g of the measured materials each time and put them into a small kneader ("MC15" manufactured by Xplore Instruments) and knead at a temperature of 200 °C for 5 minutes. Using an Xplore injection molding machine (manufactured by Xplore Instruments), under the conditions of a heating cylinder (cylinder) temperature of 200 °C and a mold temperature of 40 °C, 5 dumbbell-shaped test pieces (type A12, JIS K7139) and 8 strip-shaped test pieces (type B1, JIS K7139) were molded.

[0057] <Tensile strength (MPa)> For the obtained dumbbell-shaped test pieces, using a precision universal testing machine ("Autograph AG-Xplus" manufactured by Shimadzu Corporation), in accordance with JIS K 7161: Plastics - Test method for tensile properties, the tensile stress was measured at a test speed of 1 mm / min and an initial gauge length of 30 mm, and the maximum value was taken as the tensile strength. The average value of the tensile strengths of the 5 test pieces was taken as the tensile strength of the sample. The tensile strength of the resin (BC10HRF) alone was 19.2 MPa.

[0058] <Flexural strength (MPa)> For the obtained strip-shaped test pieces, using a precision universal testing machine ("Autograph AG-Xplus" manufactured by Shimadzu Corporation), in accordance with JIS K 7171, a flexural test was conducted with a support span of 64 mm and a test speed of 10 mm / min. The maximum flexural stress that the test piece could withstand during the flexural test was defined as the flexural strength. The average value of the flexural strengths of three test pieces was defined as the flexural strength of the sample. The flexural strength of the resin (BC10HRF) alone was 28.5 MPa.

[0059] <Charpy impact strength (kJ / m 2 )> For the obtained strip-shaped test pieces, a Charpy impact test was performed using a Charpy impact tester (model: IT, manufactured by Toyo Seiki Seisaku-sho, Ltd.). A notch with a depth of 2 mm was inserted into the center of the test piece. The opposite side of the notch was struck using a pendulum of JC005J (0.5 J), and the impact strength was calculated. The average value of the Charpy impact strengths of five test pieces was defined as the Charpy impact strength of the sample.

[0060] <Preparation of powdered cellulose> (Example 1) Using a sun-dried kraft pulp sheet (LBKP dry sheet, manufactured by Nippon Paper Industries Co., Ltd., moisture content 4.4%) derived from hardwood in which 75% is acacia wood as a raw material, after coarsely pulverizing it with a cutting mill (PI-20120, manufactured by Horai Co., Ltd., screen diameter Φ3 mm), it was pulverized with a cutting mill (HA8-2542, manufactured by Horai Co., Ltd., main mesh: 165 mesh, auxiliary mesh: 20 mesh) to obtain powdered cellulose 1 with a moisture content of 2.3%.

[0061] (Example 2) Except for using a sun-dried kraft pulp sheet (LBKP dry sheet, manufactured by Nippon Paper Industries Co., Ltd., moisture content 7%) derived from hardwood in which 60% is acacia wood as a raw material, it was processed in the same manner as in Example 1 to obtain powdered cellulose 2 with a moisture content of 2.7%.

[0062] (Example 3) Except that a sun-dried kraft pulp sheet derived from hardwood with 35% being acacia wood (LBKP dry sheet, manufactured by Nippon Paper Industries Co., Ltd., moisture content 6.9%) was used as the raw material, the treatment was the same as in Example 1, and powdery cellulose 3 with a moisture content of 2.6% was obtained.

[0063] (Comparative Example 1) Using a sun-dried kraft pulp sheet derived from hardwood with 35% being acacia wood (LBKP dry sheet, manufactured by Nippon Paper Industries Co., Ltd., moisture content 6.9%), the sheet was roughly pulverized with a uniaxial crusher, and then primary pulverization was performed with a vertical roller mill (manufactured by Hatsuratsu Co., Ltd.) at a supply rate of 30 kg / h, a classifier frequency of 22 Hz, and a pulverizing roller frequency of 55 Hz. After that, secondary pulverization was performed with the same apparatus at a supply rate of 50 kg / h, a classifier frequency of 43 Hz, and a pulverizing roller frequency of 55 Hz to obtain powdery cellulose 4 with a moisture content of 1.9%.

[0064] (Comparative Example 2) Using a sun-dried kraft pulp sheet derived from softwood (NBKP dry sheet, manufactured by Nippon Paper Industries Co., Ltd., moisture content 11.6%) as the raw material, it was roughly pulverized with a cutting mill (PI-20120, manufactured by Horai Co., Ltd., screen diameter Φ3 mm), and then the pulverized product obtained by pulverizing with a cutting mill (HA8-2542, manufactured by Horai Co., Ltd., main mesh: 165 mesh, auxiliary mesh: 20 mesh) was further pulverized with a vertical roller mill (manufactured by Hatsuratsu Co., Ltd.) at a supply rate of 40 Kg / h, a classifier frequency of 45 Hz, and a pulverizing roller frequency of 55 Hz to obtain powdery cellulose 5 with a moisture content of 3.1%.

[0065] (Comparative Example 3) Using a sun-dried kraft pulp sheet derived from softwood (NBKP dry sheet, manufactured by Nippon Paper Industries Co., Ltd., moisture content 10%) as the raw material, the sheet was roughly pulverized with a uniaxial crusher, and then primary pulverization was performed with a vertical roller mill (manufactured by Hatsuratsu Co., Ltd.) at a supply rate of 30 Kg / h, a classifier frequency of 14 Hz, and a pulverizing roller frequency of 55 Hz. After that, secondary pulverization was performed with the same apparatus at a supply rate of 45 kg / h, a classifier frequency of 28 Hz, and a pulverizing roller frequency of 55 Hz to obtain powdery cellulose 6 with a moisture content of 3.5%.

[0066] (Comparative Example 4) Using as a raw material a hardwood-derived sun-dried sulfite pulp sheet (LDPT dry sheet, manufactured by Nippon Paper Industries Co., Ltd., moisture content 7%) containing 10% acacia wood, acid hydrolysis was carried out at 90 °C for 40 minutes with 0.5 N hydrochloric acid at a pulp slurry concentration of 5%, followed by neutralization, washing, and drying to obtain powdery cellulose 7 with a moisture content of 6.7%.

[0067] (Comparative Example 5) Using as a raw material a hardwood-derived sun-dried sulfite pulp sheet (LDPT dry sheet, manufactured by Nippon Paper Industries Co., Ltd., moisture content 6.2%) not containing acacia wood, the treatment was carried out in the same manner as in Example 2 except that the mesh size during pulverization with a cutting mill (HA8-2542) was 50 mesh to obtain powdery cellulose 8 with a moisture content of 5.5%.

[0068] [Table 1]

[0069] In Examples 1 to 3, which are derived from hardwood bleached kraft pulp (LBKP) with a particle size and aspect ratio within a predetermined range and containing 25% or more of acacia-derived pulp, the tensile strength, flexural strength, and Charpy impact strength when made into a resin composition were good compared to Comparative Examples 1 to 5.

Claims

1. Powdery cellulose for a molding resin material, having a particle diameter D50 of 10 to 100 μm and an aspect ratio of 4.0 to 10.0, wherein the raw material pulp of the powdery cellulose is hardwood kraft pulp (LBKP) containing 25% or more of pulp derived from acacia.

2. The powdery cellulose for a molding resin material according to claim 1, having an average fiber length of 140 to 200 μm when measured with a fiber tester plus.

3. The powdery cellulose for a molding resin material according to claim 1, wherein the value obtained by subtracting the particle diameter D50 from the particle diameter D90 of the powdery cellulose (particle diameter D90 - particle diameter D50) is 80 to 140 μm.

4. A molding resin material comprising the powdery cellulose and a thermoplastic resin.

5. The molding resin material according to claim 4, wherein the content of the powdery cellulose is 10% by weight or more when the molding resin material is 100% by weight.

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