Powdered cellulose

Abstract

To provide a powdered cellulose capable of suppressing coloration when used in a resin composition.SOLUTION: The invention provides a powdered cellulose having a particle diameter D.50 of 10-100 μm and a kappa number of 1.5 or less, where the whiteness of the cellulose raw material for the powdered cellulose is 83% or higher. Preferably, the powdered cellulose has a thermal weight loss rate of less than 5% at 110°C to 300°C when heated at a rate of 20°C / min in thermogravimetric analysis (TG).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 their use in exterior components such as housings for home appliances and interior and exterior components for automobiles. In addition to mechanical strength such as rigidity and impact strength, which are required characteristics of exterior components, when the resin composition is used for, for example, white-colored housings for home appliances or automobile parts, the color of the resin composition is important and must be transparent or close to white. However, since general cellulose fibers become discolored when heated, when a resin composition containing a large amount of powdered cellulose is injection molded, discoloration due to the powdered cellulose becomes a problem.

[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 can suppress coloration when made into a resin composition. [Means for solving the problem]

[0006] The present invention provides the following [1] to [4]. [1] Powdered cellulose having a particle diameter D50 of 10 to 100 μm and a kappa number of 1.5 or less, wherein the whiteness of the powdered cellulose in a cellulose raw material is 83% or more. [2] The powdery cellulose according to [1], which has a thermal weight loss rate of less than 5% at 110°C to 300°C when heated at a temperature of 20°C / min in a thermal analyzer (TG). [3] The powdered cellulose according to [1] or [2], wherein the raw material pulp is pulp derived from a coniferous tree. [4] The powdered cellulose according to [1] or [2], wherein the raw material pulp is pulp derived from hardwood. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide powdered cellulose that can suppress coloration when made into a resin composition. DETAILED DESCRIPTION OF THE INVENTION

[0008] [1. Powdered cellulose] The powdered cellulose of the present invention has a particle size D50 of 10 to 100 μm and a kappa number of 1.5 or less, and the whiteness of the raw material pulp for the powdered cellulose is 83% or more.

[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 (D50) 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)] The average fiber length is preferably 30 μm or more, more preferably 50 μm or more, and the upper limit is preferably 200 μm or less, more preferably 150 μm or less.

[0012] The average fiber width 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 35 μm or less.

[0013] The powdered cellulose has an average fiber length / average fiber width (L / D) ratio of preferably 2.0 to 7.0, more preferably 2.0 to 6.0, and even more preferably 2.0 to 5.0. When L / D is 2.0 to 7.0, the resin composition containing the powdered cellulose has good fluidity, making it less susceptible to excessive shear heat and reducing coloration.

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

[0015] [1.3. Kappa number (KN)] The kappa number of the powdery cellulose of the present invention is 1.5 or less, and more preferably 1.3 or less. The kappa number is an index of the amount of compounds such as lignin and hexenuronic acid that are oxidized by potassium permanganate, and by having the kappa number be within the above range, coloration resulting from compounds such as lignin and hexenuronic acid that are oxidized by potassium permanganate can be suppressed when a resin composition containing the powdery cellulose is prepared. The kappa number can be measured in accordance with JIS P8211.

[0016] [1.4. Thermogravimetric reduction rate] The powdered cellulose of the present invention typically exhibits a thermal weight loss rate of less than 5%, preferably 4% or less, at 110°C to 300°C when heated at 20°C / min in a thermal analyzer under a nitrogen atmosphere. If the thermal weight loss rate is less than 5%, coloration can be suppressed when the cellulose is heated and kneaded with a resin and then injection molded. The lower limit is not particularly limited, but is, for example, 0.5% or more, 1% or more, or 2% or more.

[0017] The thermal weight retention rate can be determined by using a thermal analyzer such as TG to read the weights at 110°C and 300°C when the temperature is raised from 35°C to 550°C at a rate of 20°C / min in a nitrogen atmosphere, and then determining the rate of change as the thermal weight loss rate (%).

[0018] [2. 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 (LUSP), bleached hardwood sulfite pulp (LBSP), bleached softwood dissolving sulfite pulp (NDSP), bleached hardwood dissolving sulfite pulp (LBSP), bleached softwood dissolving sulfite pulp (NDSP), bleached hardwood dissolving sulfite pulp (LBSP), bleached softwood dissolving sulfite pulp (LBSP), bleached hard ... Examples of suitable pulps include wood-derived pulp such as LDSP (Light-Duty Pulp), 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). However, bleached pulp and bleached dissolving pulp, which have a low lignin content, are preferred in that they can suppress discoloration when mixed with resin and injection molded. Furthermore, pulp derived from softwood is more preferable than hardwood pulp because it has a relatively low hemicellulose content. Particularly preferred are softwood bleached kraft pulp (NBKP), softwood bleached dissolving sulfite pulp (NDSP), and hardwood bleached dissolving sulfite pulp (LDSP).

[0019] 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) methods include sulfite cooking, kraft cooking, soda-quinone cooking, and organosolv cooking. Kraft pulp is preferred from an environmental and economic perspective, while sulfite cooking is preferred due to its low hemicellulose content. 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 pulp can be cooked using alkaline chemicals alone. Furthermore, since a small amount of hemicellulose can suppress discoloration when heated and kneaded with a resin, a pre-hydrolysis treatment may be carried out before the kraft cooking.

[0020] 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 The pressure is preferably 4 to 7 kg / cm2, the 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 known conditions can be applied. In the present invention, the oxygen delignification treatment may be carried out multiple times.

[0021] The pulp that has been subjected to the oxygen delignification treatment may then be sent to a washing step, for example, 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 JIS P8148.

[0022] 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, ZEop-DD, Z / D-Eop-D, and Z / D-Eop-DED (the " / " in the sequence indicates that the treatments before and after " / " 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).

[0023] 2.1. Whiteness of cellulose raw materials The whiteness of the cellulose raw material of the present invention is preferably 83% or more, more preferably 84% or more. When the whiteness of the cellulose raw material is 83% or more, discoloration can be suppressed when the resin composition containing powdered cellulose is prepared. The upper limit is not particularly limited, and is, for example, 100% or less, 99% or less, or 98% or less. The whiteness in the present invention can be measured according to JIS P8148.

[0024] 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.

[0025] 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.

[0026] [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.

[0027] Examples of the crusher (disintegrator) 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, a freeze crusher, a uniaxial crusher, and a biaxial crusher, and these may be used alone or in combination of two or more.

[0028] 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.).

[0029] 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.).

[0030] 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.).

[0031] 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).

[0032] Examples of roller mills include a vertical roller mill (manufactured by Seishin Co., Ltd.), a vertical roller mill (manufactured by Chinon 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.), an IS mill (IHI Plant Engineering Co., Ltd.), and a vertical roller mill (Hatsuratsu Co., Ltd.). Of these, cutting mills and roller mills are preferred.

[0033] 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.

[0034] -Neutralization, washing, dehydration, drying treatment- The cellulose raw material undergoes an appropriate pretreatment before being subjected to a pulverization treatment. Examples of pretreatment include neutralization, washing, deliquoring, and drying, and it is preferable to perform dehydration and drying treatments 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. The solids concentration of the cellulose raw material immediately before being subjected to a pulverization treatment is usually 15% or more, preferably 20% or more, more preferably 30% or more, even more preferably 40% or more, and particularly preferably 50% or more, 60% or more, 70% or more, 80% or more, 90% or more, or 94% or more, and can be adjusted as appropriate.

[0035] -Acid hydrolysis treatment- Examples of acids used in acid hydrolysis include mineral acids such as hydrochloric acid, sulfuric acid, and nitric acid. While the acid concentration is not particularly limited, 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. When the acid concentration is less than 0.1 N, acid-induced depolymerization of cellulose is suppressed, reducing the decrease in the degree of polymerization of cellulose, but micronization may become difficult. On the other hand, when the acid concentration exceeds 2.0 N, depolymerization of cellulose progresses, facilitating micronization, improving powder fluidity. However, the decrease in the degree of polymerization increases the likelihood of discoloration when mixed with a resin and injection-molded. While the reaction conditions for acid hydrolysis are not particularly limited, the reaction temperature is typically 80 to 100°C, and the reaction time is typically 30 minutes to 3 hours.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] [4. Uses of powdered cellulose] Other uses of powdered cellulose include, for example, industrial additives (for example, for thermoplastic resins (e.g., polyolefin resins such as polypropylene, modified polyolefin resins such as maleic anhydride-modified polyolefin), thermosetting resins (e.g., phenolic resins, melamine resins), and various rubbers). It can also be used as a component or raw material for resin compositions (e.g., compositions containing thermoplastic resins such as polyolefin resins and modified polyolefin resins, thermosetting resins, and / or rubber), rubber compositions (e.g., automobiles, personal computers, building materials, containers), food additives (e.g., shredded cheese, fried products, breadcrumbs, ham and sausage casings, and their pickling solutions), hygiene products / cosmetics (e.g., facial cleansers, dentifrices, foundations), filter aids (e.g., rare metals, food), paint / adhesive additives (e.g., urethane paints), and feed (e.g., pet food, fishing bait). Among these, additives to resins (resin compositions) are preferred, and those for home appliance housings or automobiles are more preferred. This can suppress discoloration of the product.

[0040] When added to a resin, the amount of powdered cellulose relative to the total amount of resin and powdered cellulose can be determined appropriately depending on the type of resin, application, etc., but is usually 5% by weight or more, 10% by weight or more, 15% by weight or more, or 20% by weight or more. This allows the effect as a reinforcing agent to be exerted. Since the powdered cellulose of the present invention can suppress coloration of the resin composition, it can be added in large amounts, so the upper limit is not particularly limited, but is, for example, 80% by weight or less, 70% by weight or less. [Example]

[0041] 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.

[0042] <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.

[0043] 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

[0044] 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

[0045] <Average fiber length (μm), average fiber width (μm), L / D> Measurements were carried out 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 7 μm 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 powdered cellulose. 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 obtained average fiber length was divided by the average fiber width to calculate L / D.

[0046] <Kappa number> The kappa number was determined in accordance with JIS P 8211.

[0047] <Thermogravimetric reduction rate> The thermal weight loss rate was measured by measuring the weight of powdered cellulose at 110°C and 300°C when the temperature was raised 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). The weight change was calculated as the thermal weight loss rate (%). 5–15 mg of powdered cellulose was weighed onto a platinum pan. Thermal weight loss rate (%) = 100 × (weight at 1-300°C / weight at 110°C)

[0048] <Whiteness> The brightness of the raw pulp sheet was measured according to JIS P 8148 using an ISO brightness / opacity measuring instrument (CMS-35SPXM, manufactured by Murakami Color Research Laboratory Co., Ltd.).

[0049] <Color (resin composition)> A resin composition containing powdered cellulose was prepared as follows. 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 ratio of 51:48.5:0.5 to make a total of 8 g, and eight batches were prepared. Each 8 g of the weighed materials was placed in a small kneading machine ("MC15," manufactured by Xplore Instruments) and kneaded for 5 minutes at a heating barrel (cylinder) temperature of 200°C. Eight rectangular test specimens (JIS K7139) were molded using an Xplore injection molding machine (manufactured by Xplore Instruments) at a mold temperature of 40°C. The first three were discarded, and the remaining five were used for color evaluation. The CIE L of the rectangular test specimens was measured using a spectrophotometer (eXact, manufactured by Videojet X-Rite Inc.). * , a * , b * Measure at three points per test piece, and the average value is the L of the test piece. * , a * , b * The illuminant during measurement was D50, the observation field was 2°, the density status was T, and the measurement conditions were M0 (N o ) No filter was selected. This measurement was carried out on a total of five test pieces, and the average value of n = 5 was used as the L of the sample. * , a * , b * The saturation of the sample C * (a * , b * When is a positive value, C * The larger the value, the stronger the redness or yellowness, or both. * The L value (the larger the value, the greater the discoloration) was calculated according to the following formula. * , a * , b * are L * 0, a * 0, b * 0, and L * 0 is 52.3, a * 0 is -1.0, b * 0 was -2.4.

number

[0050] <Strength test> Dumbbell-shaped tensile test specimens (JIS K7139) were prepared using an Xplore injection molding machine (manufactured by Xplore Instruments) in the same manner as in the color test. The maximum stress and breaking strain in the tensile test (in accordance with JIS K7161-1:2014) were measured. Also, rectangular test specimens (JIS K7139) prepared in the same manner as in the color test were measured. The maximum stress and breaking strain in the bending test (in accordance with JIS K7171:2016) were measured.

[0051] <MFR(g / 10min)> Similar to the color test method, the resin composition was kneaded in a small kneader at 200°C for 5 minutes, and the melt flow rate (MFR) of the resin composition was measured using a melt flow indexer (G-02, manufactured by Toyo Seiki Seisakusho Co., Ltd.) in accordance with JIS K7210 under conditions of a measurement temperature of 230°C and a test load of 2.16 kg.

[0052] <Preparation of powdered cellulose> Example 1 Using softwood bleached kraft pulp dry sheets (NBKP, Nippon Paper Industries Co., Ltd., moisture 6%) with a brightness of 85.1% as the raw material, 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. This was followed by 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, yielding powdered cellulose 1. Various physical properties are listed in Table 1.

[0053] Example 2 Using softwood bleached kraft pulp dry sheets (NBKP, manufactured by Nippon Paper Industries Co., Ltd., moisture content 6%) with a brightness of 84.1% as the raw material, the sheets were coarsely crushed in a uniaxial crusher and then crushed in a vertical roller mill (Hatsuratsu Co., Ltd.) at a feed rate of 28 kg / h, a classifier frequency of 14 Hz, and a crushing roller frequency of 55 Hz to obtain powdered cellulose 2. Various physical properties are shown in Table 1.

[0054] Example 3 Powdered cellulose 3 was obtained in the same manner as in Example 1, except that a hardwood bleached dissolved sulfite pulp dry sheet (LDSP, brand: LDPT, manufactured by Nippon Paper Industries Co., Ltd., moisture content: 6%) with a brightness of 93.1% was used and the feed rate for the primary grinding was 41 kg / h, the classifier frequency was 28 Hz, and the feed rate for the secondary grinding was 41 kg / h, and the classifier frequency was 48 Hz. Various physical property values ​​are shown in Table 1.

[0055] (Comparative Example 1) Powdered cellulose 4 was obtained in the same manner as in Example 1, except that a hardwood bleached kraft pulp dry sheet (LBKP, manufactured by Nippon Paper Industries Co., Ltd., moisture content 7%) with a brightness of 86.4% was used, the feed rate for the primary grinding was 30 kg / h, the classifier frequency was 22 Hz, and the feed rate for the secondary grinding was 50 kg / h, and the classifier frequency was 43 Hz. Various physical property values ​​are shown in Table 1.

[0056] (Comparative Example 2) Softwood bleached kraft pulp dry sheet (NBKP, Nippon Paper Industries Co., Ltd., moisture content 8%) with a brightness of 80.9% was used as the raw material. It was coarsely pulverized using a cutting mill (PI-20120, Horai Co., Ltd., screen diameter Φ3 mm) and then pulverized using a cutting mill (HA8-2542, Horai Co., Ltd., main mesh: 165 mesh, auxiliary mesh: 20 mesh). The resulting pulverized material was further pulverized using a vertical roller mill (Hatsuratsu Co., Ltd.) at a feed rate of 40 kg / h, a classifier frequency of 45 Hz, and a milling roller frequency of 55 Hz to obtain powdered cellulose 5. Various physical properties are listed in Table 1.

[0057] [Table 1]

[0058] In Examples 1 to 3, in which the kappa number of the powdered cellulose and the whiteness of the raw material pulp are within the predetermined range, the C value of the resin composition is lower than that of Comparative Examples 1 and 2, in which the kappa number of the powdered cellulose and the whiteness of the raw material pulp are outside the range. * and ΔE * The values ​​of the powdered cellulose of Examples 1 to 3 were all small and had good color. Furthermore, the thermal weight loss rate was suppressed to less than 5%, indicating that no coloration occurred. Furthermore, the results of the strength test and MFR measurement indicated that Examples 1 to 3 were equivalent to those of Comparative Examples 1 and 2, demonstrating consistent strength and fluidity. These results indicate that the powdered cellulose of the present invention can be used as a reinforcing agent for resin materials, particularly for exterior components such as housings for home appliances and interior and exterior components of automobiles, where coloration is often a problem.

Claims

1. 1. A powdery cellulose having a particle diameter D50 of 10 to 100 μm and a kappa number of 1.5 or less, wherein the whiteness of the powdery cellulose in a cellulose raw material is 83% or more.

2. 2. The powdered cellulose according to claim 1, which has a thermal weight loss rate of less than 5% at 110°C to 300°C when heated at a temperature of 20°C / min in a thermal analyzer (TG).

3. 3. The powdered cellulose according to claim 1 or 2, wherein the raw material pulp is pulp derived from a coniferous tree.

4. 3. The powdered cellulose according to claim 1 or 2, wherein the raw material pulp is pulp derived from hardwood.

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