Powdery cellulose

Abstract

To provide powdery cellulose which can suppress coloration, silver streak and odor, when being formed into a resin composition.SOLUTION: Powdery cellulose has an average particle diameter of 10 to 100 μm, wherein when the powdery cellulose is 100 wt.%, a hemicellulose content is less than 10 wt.%, and when the temperature is raised under the condition of 20°C / min in a thermal analysis device (TG), a heat weight reduction rate at 110°C to 300°C is less than 5%.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] 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 parts such as housings for home appliances and interior and exterior parts for automobiles. In addition to mechanical strength such as rigidity and impact strength, which are required characteristics of exterior parts, when the resin composition is used for, for example, white-colored housings for home appliances or parts for automobiles, the color of the resin composition is important and it is required to be transparent or close to white. However, since general cellulose fibers become discolored by heating, when a resin composition containing a large amount of powdered cellulose is injection molded, coloring and silver streaks originating from the powdered cellulose become a problem. In addition, when a resin composition containing powdered cellulose is injection molded, odor generation becomes an issue.

[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 which can suppress discoloration, silver streaks, and odor 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 an average particle size of 10 to 100 μm, a hemicellulose content of less than 10% by weight when the powdered cellulose is taken as 100% by weight, and a thermal weight loss rate of less than 5% at 110°C to 300°C when heated at 20°C / min in a thermal analyzer (TG). [2] The powdery cellulose according to [1], having an average fiber length / average fiber width (L / D) of 2.0 to 7.0. [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 broad-leaved trees. Effect of the Invention

[0007] According to the present invention, it is possible to provide a powdered cellulose which can suppress coloration, silver streaks, and odor when made into a resin composition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [1. Powdered cellulose] The powdered cellulose has a given average particle size and hemicellulose content, and exhibits a thermal weight loss rate of less than 5% at 110° C. to 300° C. when heated at 20° C. / min in a thermal analyzer (TG).

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

[0010] -Wet measurement (with ultrasonic irradiation)- In this specification, wet conditions (with ultrasonic irradiation) refer to conditions in which water is added to a sample, ultrasonic irradiation is performed, and then the particle size is measured. The preferred ranges of D.10, D.50, and D.90 in the case of wet conditions (with ultrasonic irradiation) are as follows. In general, the larger the particle size, the more likely the fibers are to become entangled. Furthermore, by being within the following ranges, when added to resins, rubbers, etc., the strength can be appropriately improved without impairing their properties. 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 μm or less, and more preferably 15.0 μm or less. Therefore, it is usually 3.0 to 20.0 μm, preferably 5.0 to 17.0 μm, and more preferably 10.0 to 15.0 μm. 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 32.0 μm or more (but 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. Therefore, D.50 is usually 10.0 to 100.0 μm, preferably 20.0 to 80.0 μm, more preferably 30.0 to 60.0 μm, and even more preferably 32.0 to 50.0 μm. D.90 is usually 50.0 μm or more, preferably 70.0 μm or more, and more preferably 80.0 μm or more (but 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 150.0 μm or less. Therefore, D.90 is usually 50.0 to 200.0 μm, preferably 70.0 to 180.0 μm, and more preferably 80.0 to 150.0 μm.

[0011] [1.2. Average fiber width (μm), average fiber length (μm), average fiber length / average fiber width (L / D)] The average fiber length of the powdered cellulose is preferably 30 μm or more, more preferably 50 μm or more, and the upper limit is preferably 300 μm or less, more preferably 200 μm or less.

[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 35 μm or less.

[0013] The powdered cellulose has an average fiber length / average fiber width (L / D) of preferably 2.0 to 8.0, more preferably 2.0 to 7.0, and even more preferably 2.0 to 6.0 or 2.0 to 5.0. When L / D is within the above range, preferably 2.0 to 7.0, the resin composition containing the powdered cellulose has good fluidity, so that excessive shear heat is unlikely to be applied, and coloring, silver streaks, and odors can be suppressed.

[0014] The average fiber length and average fiber width can be measured using ABB Fiber Tester Plus. 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 measured values.

[0015] [1.3.NDF] NDF is an abbreviation for neutral detergent fiber, and indicates organic matter that does not dissolve when a sample is boiled in a neutral detergent solution, and is generally a value indicating the total fiber amount. The NDF in the powdered cellulose of the present invention is mainly a value obtained by adding up the amount of cellulose, the amount of hemicellulose, and the amount of lignin. The NDF content in the powdered cellulose is preferably 70% by weight or more, more preferably 80% by weight or more, more preferably 85% by weight or more, and more preferably 90% by weight or more, when the powdered cellulose is 100% by weight. The upper limit is not particularly limited, and may be, for example, 100% by weight or less, 99% by weight or less.

[0016] In this specification, the NDF content can be measured under the following conditions, and the values ​​in the examples are also values ​​measured by the following method. Accurately weigh 2-5 g of the sample to be analyzed into an aluminum weighing dish (previously dried and accurately weighed), dry at 135±2°C for 2 hours, cool in a desiccator, weigh accurately, and calculate the water content in the sample. Measure 18.6 g of disodium dihydrogen ethylenediaminetetraacetate dihydrate, 6.8 g of sodium borate decahydrate, and 4.6 g of disodium hydrogen phosphate into a 1L volumetric flask, and add 500 mL of water to dissolve. Add 30.0 g of sodium n-dodecyl sulfate, 10 mL of triethylene glycol, and 250 mL of water to this solution, mix, and then add water up to the mark on the volumetric flask to prepare a neutral detergent solution. Before use, confirm that the pH is in the range of 6.95-7.05. Accurately weigh 0.5 g of the sample to be analyzed and place it in a 500 mL tall beaker. After adding 0.5 g of sodium sulfite and 50 mL of neutral detergent solution, cover the tall beaker with a watch glass or cooler and heat it to boiling in a preheated fiber boiling device. After boiling for 1 hour while replacing the water that evaporates, remove the tall beaker from the fiber boiling device and suction filter the contents of the tall beaker with a glass filter (P2, Foss Tecator, pore size 40-100 μm, or equivalent). Wash the residue in the glass filter (neutral detergent insoluble matter) with 40 mL of hot water three times, wash it with 10-20 mL of acetone three to four times, and then air dry it until the acetone odor disappears. Next, dry the glass filter at 135 ± 2 ° C for 2 hours, cool it in a desiccator, and accurately weigh the weight of the neutral detergent insoluble matter. The glass filter is then heated at 520-550°C for 2-5 hours to convert the neutral detergent insolubles to ashes, then heated at 150°C for 2 hours, allowed to cool in a desiccator, and the weight of the ash is accurately weighed. The amount of ash is subtracted from the amount of the neutral detergent insolubles to calculate the NDF (% of dry matter) in the sample.

[0017] [1.4.ADF] ADF is an abbreviation for acid detergent fiber, and is a value indicating organic matter that does not dissolve when a sample is boiled in an acid detergent solution. The ADF in the powdered cellulose of the present invention is mainly a value obtained by adding up the amount of cellulose and the amount of lignin. The ADF content in the powdered cellulose is preferably 70% by weight or more, more preferably 75% by weight or more, and more preferably 85% by weight or more, and more preferably 90% by weight or more, when the powdered cellulose is 100% by weight. The upper limit is not particularly limited, and may be 100% by weight or less, 99% by weight or less, or 98% by weight or less.

[0018] In this specification, the ADF content can be measured under the following conditions, and the values ​​in the examples are also values ​​measured by the following method.

[0019] Accurately weigh 2-5 g of the sample to be analyzed and place it in an aluminum weighing dish (previously dried and accurately weighed), dry it at 135±2°C for 2 hours, cool it in a desiccator, weigh it accurately, and calculate the amount of water in the sample. Add 20 g of cetyltrimethylammonium bromide to 1 L of sulfuric acid (1+37) and dissolve to prepare an acid detergent solution. Accurately weigh 1 g of the sample to be analyzed and place it in a 500 mL tall beaker, add 100 mL of acid detergent solution, cover the tall beaker with a watch glass or cooler, and boil. After boiling for 1 hour while replacing the water that evaporates, suction filter the contents of the tall beaker with a glass filter (P2, Foss Tecator, pore size 40-100 μm, or equivalent). The residue in the glass filter (acid detergent insolubles) is thoroughly washed with hot water, and then washed 3-4 times with 10-20 mL of acetone, and then air-dried until the acetone odor disappears. Next, the glass filter is dried at 135°C for 2 hours, cooled in a desiccator, and the weight of the acid detergent insolubles is accurately weighed. The glass filter is further heated at 520-550°C for 2 hours to incinerate the acid detergent insolubles, heated at 150°C for 2 hours, cooled in a desiccator, and the weight of the ash is accurately weighed. The ADF (% of dry matter) in the sample is calculated by subtracting the amount of ash from the amount of acid detergent insolubles obtained earlier.

[0020] [1.5. Hemicellulose] The powdered cellulose may contain hemicellulose. The amount of hemicellulose in the powdered cellulose is usually less than 10% by weight, preferably 7% by weight or less, more preferably 5% by weight or less, and even more preferably 4% by weight or less, when the powdered cellulose is taken as 100% by weight. If the amount of hemicellulose is less than 10% by weight, coloring, silver streaks, and odor of the resin composition when heated and kneaded with a resin can be suppressed. The lower limit is not particularly limited, and may be, for example, 0% by weight or more, 0.01% by weight or more, or 0.05% by weight or more.

[0021] The hemicellulose content can be calculated from the difference between the above NDF and ADF.

[0022] [1.6. Thermogravimetric reduction rate] The powdered cellulose of the present invention has a thermal weight loss rate of usually less than 5%, preferably 3% 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%, odor and silver streaks 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 1.5% or more.

[0023] The thermal weight retention rate can be determined by reading the weights at 110°C and 300°C when the temperature is raised from 35°C to 550°C at 20°C / min in a nitrogen atmosphere using a thermal analyzer such as TG, and confirming the rate of change as the thermal weight loss rate (%).

[0024] [2. Cellulose raw materials] The cellulose raw material is usually naturally derived cellulose, and is preferably pulp, more preferably pulp derived from wood such as softwood or hardwood. Examples of wood-derived pulp include softwood unbleached kraft pulp (NUKP), softwood bleached kraft pulp (NBKP), hardwood unbleached kraft pulp (LUKP), hardwood bleached kraft pulp (LBKP), softwood bleached dissolving kraft pulp (NDKP), hardwood bleached dissolving kraft pulp (LDKP), softwood unbleached sulfite pulp (NUSP), softwood bleached sulfite pulp (NBSP), hardwood unbleached sulfite pulp (LUSP), and other kraft pulps. Chemical pulps such as sulfite pulp, hardwood bleached sulfite pulp (LBSP), softwood bleached dissolved sulfite pulp (NDSP), hardwood bleached dissolved sulfite pulp (LDSP), etc.; mechanical pulp such as thermomechanical pulp (TMP), pressurized groundwood pulp (PGW), refiner groundwood pulp (RGP), alkaline hydrogen peroxide mechanical pulp (APMP), and alkaline hydrogen peroxide thermomechanical pulp (APTMP). Among these, chemical pulps (kraft pulp, sulfite pulp) are preferred, with NBKP, LDKP, and LDSP being preferred, and NBKP and LDSP being more preferred.

[0025] Examples of methods for preparing wood-derived pulp include chemical pulping (cooking) methods. By chemical pulping (cooking), lignin, a coloring substance, is dissolved and removed, and by combining this with oxygen delignification and bleaching, pulp with high whiteness can be obtained. Examples of chemical pulping (cooking) methods include sulfite cooking, kraft cooking, soda-quinone cooking, and organosolv cooking. Kraft pulp is preferable from an environmental and economical perspective, and sulfite cooking is preferable because of its low hemicellulose content. Kraft cooking uses alkaline chemicals such as sodium hydroxide, potassium hydroxide, and sodium carbonate, and chemicals containing sulfur such as sodium sulfide and sodium sulfite, and can use quinone-based cooking aids, polysulfides, and other additives. These additives do not need to be used if cooking can be done with alkaline chemicals alone. In addition, since a small amount of hemicellulose can suppress coloring, silver streaks, and odors when heated and kneaded with a resin, a prehydrolysis treatment may be carried out before the kraft cooking.

[0026] In the method for preparing pulp, the pulp obtained by cooking can be subjected to oxygen delignification. The known medium or high consistency methods can be used for the oxygen delignification used in the present invention as is. In the medium consistency method, the pulp consistency is preferably 8 to 15 mass%, and in the high consistency method, 20 to 35 mass%. As the alkali in the oxygen delignification, sodium hydroxide or potassium hydroxide can be used, and as the oxygen gas, oxygen from the cryogenic separation method, oxygen from PSA (Pressure Swing Adsorption), oxygen from VSA (Vacuum Swing Adsorption), etc. can be used. The reaction conditions for the oxygen delignification are not particularly limited, but the oxygen pressure is preferably 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., 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.

[0027] 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.

[0028] 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).

[0029] The brightness of the pulp subjected to such bleaching treatment is preferably 70% or more based on ISO 2470.

[0030] 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. When the moisture content of the cellulose raw material is higher than the above range, the moisture content may be adjusted by a dehydration / drying treatment described below.

[0031] 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 grinding treatment is included, and a method including a mechanical grinding treatment is preferred.

[0032] [Mechanical crushing process] The pulverization process is a process in which the cellulose raw material is mechanically pulverized. Prior to the pulverization process, pretreatment such as dehydration / drying or acid hydrolysis may be performed, with dehydration / drying being preferred. Classification may be performed simultaneously with or after the pulverization process.

[0033] 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. One type of crusher may be used alone, or two or more types may be used in combination.

[0034] 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 Palman), cutter mills (manufactured by Tokyo Atomizer Manufacturing Co., Ltd.), centri-cutter (Nippon Coke and Engineering Co., Ltd.), rotary cutter mills (manufactured by Nara Machinery Works, Ltd.), turbo cutters (manufactured by Freund Turbo Corporation), and pulp crushers (manufactured by Zuikou Co., Ltd.).

[0035] Examples of the hammer mill 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.).

[0036] 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), Innomizer (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 (Nikki Examples of such mills include those manufactured by Nara Sozo Co., Ltd.), Nea Mill (manufactured by Dalton Co., Ltd.), Jiyu Crusher (manufactured by Nara Machinery Works Ltd.), New Cosmomizer (manufactured by Nara Machinery Works Ltd.), Turbo Mill (manufactured by Freund Turbo Corporation), Super Powder Mill (manufactured by Nishimura Machinery Works Ltd.), Blade Mill (manufactured by Nisshin Engineering Inc.), Super Rotor (manufactured by Nisshin Engineering Inc.), Wheeley Crusher (manufactured by Sanki Manufacturing Co., Ltd.), Pulp Crusher (manufactured by Zuikou Co., Ltd.), Jacobson Fine Crusher (manufactured by Kobe Steel Pantech Co., Ltd.), Universal Mill (manufactured by Tokuju Machinery Works Ltd.), and Continuous Vibro Mill (Euras Techno Co., Ltd.).

[0037] Examples of airflow mills include 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 Ltd.), Supersonic Jet Mill (manufactured by Japan 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 Seisakusho Co., Ltd.), and Kryptron (manufactured by EarthTechnica Corporation).

[0038] 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 Ltd.), a KVM type vertical roller mill (Earth Technica Corporation), an IS mill (IHI Plant Engineering Co., Ltd.), and a vertical roller mill (Hatsuratsu Co., Ltd.).

[0039] Of these, cutting mills and roller mills are preferred.

[0040] 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 prepared from the pulverization conditions (e.g., treatment time, input amount) and the desired physical properties of the powdered cellulose.

[0041] -Neutralization, washing, dehydration, drying process- The cellulose raw material is appropriately pretreated before the pulverization process. Examples of the pretreatment include neutralization, washing, deliquation, and drying, and it is preferable to perform dehydration and drying in this order. The solid content concentration of the cellulose raw material can be adjusted by drying (dehydration) treatment, and the physical properties of the powdered cellulose can be easily controlled. The solid content concentration is usually adjusted to 15% or more, preferably 20% or more. It is preferable to use an airflow dryer for drying. This allows the processed cellulose raw material to be dispersed in an airflow while being exposed to high-speed hot air, regardless of the form of the processed cellulose raw material, such as a cake-like solid, a slurry, or a solution, and the reduced pressure effect inside the dryer can be utilized to dry it instantly. In addition, since the time of contact with the hot air is extremely short, the product temperature can be kept low, making it ideal for drying products that are sensitive to heat or have a low melting point. The conditions for drying using an airflow dryer are not particularly limited and can be set appropriately, but an example is as follows. The outlet drying temperature is usually 80 to 180°C, preferably 90 to 160°C. The amount of air supplied is usually 150 to 350 m 3 / h, preferably 160 to 320 m 3 / h.

[0042] On the other hand, when using a spray dryer, the material is sprayed and dried instantly with hot air to produce granules. Therefore, it is often not suitable for drying solid or semi-solid objects with low moisture content, and the particles are more likely to be exposed to high heat instantaneously than when drying with an airflow dryer, which may affect the product.

[0043] -Acid hydrolysis treatment- Examples of the acid used in 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 viewpoint of maintaining the degree of polymerization and whiteness, it is preferably lower than the acid concentration in the acid hydrolysis treatment for the conventional production of powdered cellulose, more preferably 0.4 to 2.0N, and more preferably 0.5 to 1.5N. If the acid concentration is less than 0.4N, the depolymerization of cellulose by the acid is suppressed and the decrease in the degree of polymerization of cellulose can be reduced, but it may be difficult to finely pulverize the cellulose. On the other hand, if the acid concentration exceeds 2.0N, the depolymerization of cellulose progresses and finely pulverization becomes easier, so that the powder flowability improves, but the tablet hardness decreases with the decrease in the degree of polymerization (it may become easily disintegrated when molded). The reaction conditions for the acid hydrolysis treatment are not particularly limited, but the reaction temperature is usually 80 to 100°C, and the reaction time is usually 30 minutes to 3 hours.

[0044] Prior to the acid hydrolysis treatment, the cellulose raw material may be pretreated. For example, the cellulose raw material may be slurried (prepared as a dispersion liquid) and the concentration of the cellulose raw material may be adjusted. The concentration of the cellulose raw material is usually 3 to 10% by weight (solid content equivalent) relative to the dispersion liquid. When the cellulose raw material is a fluid 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 a 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-like cellulose raw material. When the cellulose raw material is a dry sheet of pulp, the pulp is usually loosened before the acid hydrolysis treatment. A crusher such as a roll crusher may be used to loosen the pulp.

[0045] In the pulverization treatment after acid hydrolysis, at least one other component (e.g., organic component, inorganic component) may be subjected to the pulverization treatment together with the acid hydrolysis product, if necessary. This can impart functionality to the powdered cellulose or improve its functionality. The amount of the other components to be blended may be appropriately selected. Furthermore, prior to the pulverization step, the acid hydrolysis product may be subjected to the above-mentioned neutralization, washing, dehydration, and drying treatments.

[0046] The powdered cellulose may be chemically treated as necessary. 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 performed when the cellulose raw material is subjected to a crushing treatment, or may be performed before a pretreatment for the crushing treatment.

[0047] [4. Uses of powdered cellulose] Other uses of the powdered cellulose include, for example, industrial additives (for resins such as thermoplastic resins (e.g., polyolefin resins such as polypropylene, modified polyolefin resins such as maleic anhydride modified polyolefins), 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 (for example, compositions containing thermoplastic resins such as polyolefin resins and modified polyolefin resins, thermosetting resins, and / or rubber), rubber compositions (for example, automobiles, personal computers, building materials, containers), food additives (for example, shredded cheese, fried products, bread crumbs, ham and sausage casings, and their pickling liquids), sanitary products / cosmetics (for example, facial cleansers, dentifrices, foundations), filter aids (for example, rare metals, food), paint / adhesive additives (for example, urethane paints), and feed (for example, pet food, fishing bait). Among these, it is preferable to use it as an additive to resins (resin compositions), and more preferably for home appliance housings or automobiles. This makes it possible to increase the strength of the product while suppressing coloring.

[0048] When added to a resin, the amount of powdered cellulose relative to the total amount of the resin and powdered cellulose can be appropriately determined depending on the type of resin, the 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 the coloring 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. EXAMPLES

[0049] The present invention will be described below with reference to examples. The following examples are not intended to limit the present invention. The 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.

[0050] <Average particle size> A laser diffraction particle size distribution measuring device (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 values ​​at which the integrated value of the volume accumulation distribution is 10%, 50%, and 90% were defined as the particle size distribution D.10, D.50, and D.90, respectively. The wet D.50 (with ultrasonic irradiation) was defined as the average particle size.

[0051] Wet measurements were performed by adding a sample to the measurement section in water stirred at 3000 rpm so that the scattering intensity was about 10%. When irradiating ultrasonic waves, ultrasonic waves were applied to the sample in water under the following conditions before wet measurements were performed. Mode: Continuous ·Strength: 100% Time: 600 seconds

[0052] The particle size distribution analysis was performed under the following conditions for all measurement conditions. Analysis: General purpose Analysis Sensitivity: Emphasis Light scattering model: Mie theory

[0053] <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 about 1 minute, and then transferred to a dedicated 300 ml beaker. The sample was set in a sample cycler and the measurement was started. The measurement was continued until the number of fibers with a fiber length of 0.1 mm or more was counted to be 55,000 or more, and the length-weighted fiber length and width-weighted fiber width were calculated, which were taken as the average fiber length and average fiber width of the powdered cellulose. Note that the measurement was performed after setting the Max value of Fines Limit to 0.0 and the Min value of Length class 1 to 0.001 on the Sample type screen, which determines the measurement conditions. The obtained average fiber length was divided by the average fiber width to calculate L / D.

[0054] <ndf> 3 g of sample was placed in an aluminum weighing dish, dried at 135°C for 2 hours, cooled in a desiccator, weighed, and the moisture content of the sample was calculated. 18.6 g of disodium dihydrogen ethylenediaminetetraacetate dihydrate, 6.8 g of sodium borate decahydrate, and 4.6 g of disodium hydrogen phosphate were weighed and placed in a 1L volumetric flask, and 500 mL of water was added to dissolve. 30.0 g of sodium n-dodecyl sulfate, 10 mL of triethylene glycol, and 250 mL of water were added to this solution and mixed, and then water was added up to the mark on the volumetric flask to prepare a neutral detergent solution. 0.5 g of sample was placed in a 500 mL tall beaker, 0.5 g of sodium sulfite and 50 mL of neutral detergent solution were added, and the tall beaker was covered with a watch glass or a cooler and heated to boiling in a preheated fiber boiling device. After boiling for 1 hour while supplementing the evaporated water, the tall beaker was removed from the fiber boiling apparatus, and the contents of the tall beaker were suction filtered through a glass filter (P2, Foss Tecator, pore size 50 μm). The residue in the glass filter (neutral detergent insolubles) was washed with hot water, further washed with acetone, and then air-dried until the acetone odor disappeared. Next, the glass filter was dried at 135 ° C for 2 hours, cooled in a desiccator, and the weight of the neutral detergent insolubles was weighed. The glass filter was further heated at 520 ° C for 3 hours to incinerate the neutral detergent insolubles, heated at 150 ° C for 2 hours, cooled in a desiccator, and the weight of the ash was accurately weighed. The amount of ash was subtracted from the amount of the neutral detergent insolubles described above to calculate the NDF (% of dry matter) in the sample.

[0055] <adf> 3 g of sample was placed in an aluminum weighing dish, dried at 135°C for 2 hours, and cooled in a desiccator, then weighed, and the moisture content in the sample was calculated. 20 g of cetyltrimethylammonium bromide was added to 1 L of sulfuric acid (1+37) and dissolved to prepare an acid detergent solution. 1 g of sample was placed in a 500 mL tall beaker, 100 mL of acid detergent solution was added, and the tall beaker was covered with a watch glass or a cooler and boiled. After boiling for 1 hour while supplementing the evaporating moisture, the contents of the tall beaker were suction filtered with a glass filter (P2, Foss Tecator, pore size 50 μm). The residue in the glass filter (acid detergent insoluble matter) was washed with hot water, further washed with acetone, and then air-dried until the acetone odor disappeared. Next, the glass filter was dried at 135°C for 2 hours, cooled in a desiccator, and the weight of the acid detergent insoluble matter was accurately weighed. The glass filter was then heated at 520°C for 3 hours to convert the acid detergent insoluble matter into incinerated matter, and then heated at 150°C for 2 hours. After cooling in a desiccator, the weight of the ash was accurately measured. The ADF (% of dry matter) in the sample was calculated by subtracting the amount of ash from the amount of acid detergent insoluble matter obtained above.

[0056] <Hemicellulose content> The amount of hemicellulose was calculated as the difference between the above NDF and ADF.

[0057] <Thermogravimetric reduction rate> The thermal weight loss rate was calculated 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 20°C / min in a nitrogen atmosphere using a thermal analyzer (TGA Q50, TA Instruments Japan, Inc.), and calculating the rate of change as the thermal weight loss rate (%). 5 to 15 g of powdered cellulose was weighed onto a platinum pan and the measurement was performed. Thermal weight loss rate (%) = 100 x (weight at 1-300°C / weight at 110°C)

[0058] <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 a total of 8 g, and eight batches were prepared. Each 8 g of the weighed material was put into a small kneader ("MC15" manufactured by Xplore Instruments), kneaded for 5 minutes at a heating barrel (cylinder) temperature of 200°C, and molded into eight rectangular test pieces (JIS K7139) 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 to evaluate the color. The CIE L of the rectangular test pieces was measured using a spectrophotometer (eXact, manufactured by Videojet X-Rite Inc.). * , a * , b * Measure at three points on each test piece, and the average value is the L of that test piece. * , a * , b * The illuminant during the measurement was D50, the observation field was 2°, the density status was T, and the measurement conditions were M0 (N0) without a filter. This measurement was performed 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 positive, C * The larger the value, the stronger the redness or yellowness, or both.) Color difference ΔE from polypropylene alone * The L value of the polypropylene alone used (the larger the value, the greater the discoloration) was calculated according to the following formula. * , a * , b * are L * 0, a * 0, b * 0, L * 0 is 52.3, a * 0 is -1.0, b * 0 was -2.4.

number

[0059] <Silver Streak> The surface of a rectangular test piece prepared by the method described above in (Color (Resin Composition)) was observed. If almost no white hazy silver streaks were observed, the test piece was rated as ⊚ (very good); if they were present on 10% or less of the test piece surface, the test piece was rated as ◯ (good); if they were present on 10% to 30% of the test piece surface, the test piece was rated as △ (fairly good); and if they were present on 30% or more of the test piece surface, the test piece was rated as × (bad).

[0060] <Odor> The above (color (resin composition)) was evaluated for odor during kneading in a small molding machine. If there was no odor, it was rated as ◯ (good), if there was a slight odor, it was rated as △ (slightly bad), and if there was a strong odor, it was rated as × (bad).

[0061] <Strength test> Dumbbell-shaped tensile test pieces (JIS K7139) were prepared using an Xplore injection molding machine (Xplore Instruments) in the same manner as in the color test, and the maximum stress and breaking strain in the tensile test (compliant with JIS K7161-1:2014) were measured. Strip-shaped test pieces (JIS K7139) were prepared in the same manner as in the color test, and the maximum stress and breaking strain in the bending test (compliant with JIS K7171:2016) were measured.

[0062] <MFR(g / 10min)> In the same manner as in the color test, 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.) at a measurement temperature of 230°C and a test load of 2.16 kg in accordance with JIS K7210.

[0063] <Preparation of powdered cellulose> Example 1 A bleached kraft pulp sheet (NBKP dry sheet, Nippon Paper Industries Co., Ltd., moisture content 10%) derived from coniferous trees was used as the raw material, and the sheet was coarsely crushed in a uniaxial crusher, and then the sheet was primarily crushed in a vertical roller mill (Hatsuratsu Co., Ltd.) at a feed rate of 30 kg / h, a classifier frequency of 14 Hz, and a crushing roller frequency of 55 Hz, and then the same device was used for secondary crushing at a feed rate of 45 kg / h, a classifier frequency of 28 Hz, and a crushing roller frequency of 55 Hz, and the crushed product obtained was used as the powdered cellulose of Example 1. Various physical property values ​​are shown in Table 1.

[0064] Example 2 A bleached dissolving kraft pulp sheet (LDKP dry sheet, Nippon Paper Industries Co., Ltd., moisture content 10%) derived from hardwood was coarsely pulverized with a cutting mill (PI-20120, Horai Co., Ltd., screen diameter Φ3 mm) and then pulverized with a cutting mill (HA8-2542, Horai Co., Ltd., main mesh: 165 mesh, auxiliary mesh: 20 mesh), and the pulverized material obtained was used as the powdered cellulose of Example 2. Various physical property values ​​are shown in Table 1.

[0065] Example 3 A bleached sulfite pulp sheet derived from hardwood (LDSP, brand: LDPT dry sheet, manufactured by Nippon Paper Industries Co., Ltd., moisture content 7.5%) was used as the raw material, and the powdered cellulose obtained by treating in the same manner as in Example 2, except that the mesh during pulverization in a cutting mill (HA8-2542) was 100 mesh, was used as the powdered cellulose of Example 3. Various physical property values ​​are shown in Table 1.

[0066] Comparative Example 1 A bleached kraft pulp sheet derived from hardwood (LBKP dry sheet, Nippon Paper Industries Co., Ltd., moisture content 7%) was used, and the powdered cellulose obtained by treating in the same manner as in Example 1, except that the classifier frequency for the primary grinding was 22 Hz, the feed rate for the secondary grinding was 50 kg / h, and the classifier frequency was 43 Hz, was used as the powdered cellulose of Comparative Example 1. Various physical property values ​​are shown in Table 1.

[0067] [Table 1]

[0068] In Examples 1 to 3, in which the amount of hemicellulose and the rate of weight loss due to heat are within a predetermined range, the evaluation of the color when made into a resin composition was good, and the generation of odor was suppressed, compared with Comparative Example 1, in which the amount of hemicellulose and the rate of weight loss due to heat were outside the range. In addition, in all of the Examples, the occurrence of silver streaks was suppressed, and the resin composition had fluidity from the MFR. Among them, it was found that Example 1 hardly generated silver streaks, and Examples 1 and 3 showed better fluidity because L / D was relatively small and MFR was relatively large. Furthermore, in each Example, the resin composition was able to exhibit a well-balanced strength. These results show that the powdery cellulose of the present invention can be used as a reinforcing agent for resin materials, and is particularly useful as a reinforcing agent for resin materials for exterior parts such as home appliance housings and automobile interior and exterior parts, in which the occurrence of coloring is likely to be a problem.< / adf> < / ndf>

Claims

1. The powdered cellulose has an average particle size of 10 to 100 μm, a hemicellulose content of less than 10% by weight when the powdered cellulose is taken as 100% by weight, and a thermal weight loss rate of less than 5% at 110° C. to 300° C. when heated at 20° C. / min in a thermal analyzer (TG).

2. The powdered cellulose according to claim 1, having an average fiber length / average fiber width (L / D) of 2.0 to 7.

0.

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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