Water-absorbing material

Abstract

The purpose of the present invention is to provide a water-absorbing material capable of exhibiting good water absorptivity. The present invention provides a cellulosic water-absorbing material for use in the civil engineering or construction industry, which includes a cellulose material having an average fiber length of 0.40 mm or longer, preferably 0.60 mm or longer, and an average aspect ratio of 20 or higher, preferably 22 or higher, wherein the percentage of fibers having a fiber length of 0.2 mm or shorter is 80% or less. More preferably, the cellulose material has a curl of 12.5% or greater, a roughness of 105 μg / m or greater, a void content of 80% or higher, and a fibril area ratio of 1.5% or higher. The cellulosic water-absorbing material is utilizable as a material for treating mud or inorganic sludge.

Description

water absorbing material

[0001] The present invention relates to a water absorbent material, and more particularly to a cellulose-based water absorbent material used in civil engineering or construction.

[0002] There is a widespread demand for the promotion of proper disposal of soil with high moisture content, such as excavated soil, by, for example, reusing it as ground material. For example, Non-Patent Documents 1 and 2 describe that when fine powder made from waste paper is added to highly water-containing mud and stirred, the fluidity of the mud is reduced, making it transportable. Patent Documents 1 and 2 describe a method for producing a soil with a structure in which cellulose fibers are entangled, an average particle diameter of 300 μm or less, and a BET specific surface area of ​​0.25 m. ２ / g or more 100m ２ It is described that a granular material having a porosity of 50% or more, expressed as (1-bulk density) / true density) x 100, can reduce the fluidity of mud and suppress an increase in volume.

[0003] Patent No. 5931267 Patent No. 5959709

[0004] Sawamura et al. (2017) Proceedings of the 12th Environmental Geotechnical Engineering Symposium, 17-5 Kida et al. (2018) The 13th Ground Improvement Symposium

[0005] The demand for mud treatment is increasing year by year, and there is a need to develop new water-absorbing materials that are different from the granular materials of Patent Documents 1 and 2.

[0006] An object of the present invention is to provide a water-absorbent material that can exhibit good water-absorbency.

[0007] The present invention provides the following items [1] to

[11] . [1] A cellulose-based water absorbent material comprising a cellulose material having an average fiber length of 0.40 mm or more, an average aspect ratio of 20 or more, a proportion of fibers with a fiber length of 0.2 mm or less of 80% or less, and a moisture content of 20% by weight or less. [2] The water absorbent material for civil engineering or construction according to [1], wherein the average fiber length of the cellulose material is 0.60 mm or more. [3] The water absorbent material for civil engineering or construction according to [1] or [2], wherein the average aspect ratio of the cellulose material is 22 or more. [4] The water absorbent material for civil engineering or construction according to [1] or [2], wherein the Runkel ratio of the cellulose material is 0.28 or more. [5] The water absorbent material for civil engineering or construction according to any one of [1] to [3], wherein the curl of the cellulose material is 12.5% ​​or more. [6] The water absorbent material for civil engineering or construction according to any one of [1] to [4], wherein the cellulosic material has a roughness of 105 μg / m or more. [7] The water absorbent material for civil engineering or construction according to any one of [1] to [5], wherein the cellulosic material has a porosity of 94% or more. [8] The water absorbent material for civil engineering or construction according to any one of [1] to [5], wherein the cellulosic material has a bulk specific gravity of 0.1 g / cm. ３ [9] The water absorbent material for civil engineering or construction according to any one of [1] to [7], wherein the average fibril area ratio of the cellulose material is 1.5% or more.

[10] The water absorbent material for civil engineering or construction according to any one of [1] to [9], wherein the cellulose material is a cellulose material derived from broad-leaved trees.

[11] Use of a cellulose material having an average fiber length of 0.40 mm or more, an average aspect ratio of 20 or more, a proportion of fibers with a fiber length of 0.2 mm or less of 80% or less, and a moisture content of 20% or less, for producing a water absorbent material for civil engineering or construction.

[0008] According to the present invention, a cellulose material having good water absorption properties is provided. Because the cellulose material of the present invention has good water absorption properties, it can be used in the civil engineering or construction industry as a water-absorbing material for treating mud or inorganic sludge.

[0009] [1. Shape of Cellulose Material] Cellulose materials usually consist of cellulose fibers intertwined to form secondary particles, and their shape can be described as, for example, cotton-like or soybean pulp-like, but it is difficult to specify a general shape. The shape of a cellulose material can be expressed by at least one of the following parameters, and among them, it is preferable that the average fiber length, average aspect ratio, and fineness are satisfied, and it is more preferable that the shape of a cellulose material further satisfy at least one of the Runkel ratio, curl, coarseness, average fibril perimeter ratio, average fibril area ratio, porosity, maximum torque voltage, and bulk specific gravity.

[0010] - Average Fiber Length - The average fiber length (length-weighted average fiber length) of the cellulose material is usually 0.40 mm or more, preferably 0.45 mm or more, more preferably 0.50 mm or more, 0.60 mm or more, even more preferably 0.70 mm or more, 0.90 mm or more, or 1.00 mm or more. The upper limit is usually 7.00 mm or less, preferably 5.00 mm or less, 4.50 mm or less, 4.00 mm or less, 3.50 mm or less, 3.00 mm or less, or 2.50 mm or less. Therefore, it is usually 0.40 to 7.00 mm, preferably 0.45 to 7.00 mm, more preferably 0.50 to 7.00 mm, 0.60 to 7.00 mm, and even more preferably 0.70 to 5.00 mm, 0.90 to 5.00 mm, or 1.00 to 5.00 mm, 0.50 to 4.50 mm, 0.50 to 4.00 mm, 0.50 to 3.5 mm, 0.50 to 3.00 mm, 0.50 to 3.00 mm, or 0.50 to 2.50 mm.

[0011] -Average Aspect Ratio- The average aspect ratio (average fiber length / average fiber width) is usually 20 or more, preferably 22 or more, more preferably 25 or more, even more preferably 27 or more, 29 or more, or 30 or more. The upper limit is usually 200 or less, preferably 150 or less, more preferably 100 or less, even more preferably 80 or less, 70 or less, or 60 or less. Therefore, it is usually 20 to 200, preferably 22 to 150, more preferably 25 to 100, even more preferably 27 to 100, 29 to 80, 30 to 80, 22 to 70, or 22 to 60, but is not particularly limited.

[0012] -Average Fiber Width- The average fiber width of the cellulose material is usually 50.0 μm or less, preferably 40.0 μm or less, and more preferably 35.0 μm or less. The lower limit is usually 13.0 μm or more, 14.0 μm or more, or 15.0 μm or more, preferably 18.0 μm or more, and more preferably 20.0 μm or more. Therefore, the average fiber width is usually 13.0 to 50.0 μm, 14.0 to 50.0 μm, or 15.0 to 40.0 μm, preferably 18.0 to 40.0 μm, and more preferably 20.0 to 35.0 μm, but is not particularly limited.

[0013] -Fine- Cellulose materials typically contain fibers with a fiber length of 0.2 mm or less, and in this specification, this weight percentage is referred to as "fine." Fine is typically 80.0% or less, preferably 70.0% or less, more preferably 69.0% or less, and even more preferably 68.0% or less. The lower limit is typically 5.0% or more, preferably 10.0% or more. Therefore, the weight percentage is typically 5.0 to 80.0%, preferably 5.0 to 70.0%, more preferably 10.0 to 70.0%, 10.0 to 69.0%, and even more preferably 10.0 to 68.0%, but is not particularly limited.

[0014] - Runkel Ratio - The Runkel ratio of the cellulose material is usually 0.15 or more, 0.17 or more, 0.20 or more, or 0.28 or more, preferably 0.29 or more, and more preferably 0.30 or more. The upper limit is usually 1.0 or less, preferably 0.95 or less, more preferably 0.90 or less, 0.80 or less, or 0.70 or less. Therefore, the Runkel ratio is usually 0.15 to 1.0, 0.17 to 1.0, 0.20 to 1.0, or 0.28 to 1.0, preferably 0.29 to 0.95, more preferably 0.30 to 0.90, 0.15 to 0.80, or 0.15 to 0.70, but is not particularly limited. The Runkel ratio is calculated by dividing twice the cell wall thickness by the diameter of the fiber lumen, and is expressed as (Runkel ratio) = (twice the fiber wall thickness) / (fiber lumen diameter). The fiber lumen diameter is expressed as (fiber lumen diameter) = fiber width - (twice the fiber wall thickness). The fiber wall thickness is typically 0.8 μm or more, 1.0 μm or more, 1.5 μm or more, 2.0 μm or more, or 2.3 μm or more, preferably 2.4 μm or more, and more preferably 2.5 μm or more. The upper limit is typically 6.0 μm or less, preferably 5.5 μm or less, and more preferably 5.0 μm or less. Therefore, it is usually 0.8 to 6.0 μm, 1.0 to 6.0 μm, 1.5 to 6.0 μm, 2.0 to 6.0 μm, 2.3 to 6.0 μm, preferably 2.4 to 5.5 μm, more preferably 2.5 to 5.0 μm, but is not particularly limited.

[0015] - Curl - The curl (degree of curvature) of a cellulose material is typically 9.0% or more, 10.0% or more, 12.5% ​​or more, preferably 13.0% or more, and more preferably 13.5% or more. The upper limit is typically 25.0% or less, and preferably 23.0% or less. Therefore, it is typically 9.0 to 25.0%, 10.0 to 25.0%, 12.5 to 25.0%, preferably 13.0 to 25.0%, and more preferably 13.5 to 23.0%, but is not particularly limited. Curl is a value calculated by the following formula: 100 - (100 × l / L), where l is the linear length between fiber ends and L is the true length of the fiber.

[0016] - Roughness - The roughness of the cellulose material is usually 50 μg / m or more, 55 μm or more, 60 μm or more, 70 μg / m or more, preferably 80 μg / m or more, more preferably 90 μg / m or more, and even more preferably 100 μg / m or more, 105 μg / m or more, or 110 μg / m or more. The upper limit is usually 500 μg / m or less, 300 μg / m or less, 250 μg / m or less, 200 μg / m or less, or 150 μg / m or less. Therefore, it is usually 50 to 500 μg / m , 55 to 500 μg / m , 60 to 500 μg / m , or 70 to 500 μg / m , preferably 80 to 500 μg / m , more preferably 90 to 300 μg / m , even more preferably 100 to 300 μg / m , 105 to 300 μg / m , 110 to 300 μg / m , 50 to 250 μg / m , 50 to 200 μg / m , or 50 to 150 μg / m , but is not particularly limited.

[0017] -Average fibril perimeter ratio- The average fibril perimeter ratio of a cellulose material is usually 1.7% or more, preferably 2.0% or more, and more preferably 2.2% or more. The upper limit is usually 30.0% or less, preferably 27.0% or less, and more preferably 25.0% or less. In the case of chemical pulp, it is preferably 10.0% or less, more preferably 8.0% or less, and even more preferably 7.0% or less. Therefore, it is usually 1.7 to 30.0%, preferably 2.0 to 27.0%, and more preferably 2.2 to 25.0%. In the case of chemical pulp, it is usually 1.7 to 10.0%, preferably 2.0 to 8.0%, and more preferably 2.2 to 7.0%, but is not particularly limited.

[0018] -Average fibril area ratio- The average fibril area ratio of the cellulose material is usually 0.5 or more, 0.7 or more, 1.0 or more, or 1.5% or more, preferably 1.6% or more, and more preferably 1.7% or more. The upper limit is usually 7.5% or less, preferably 7.0% or less. Therefore, it is usually 0.5 to 7.5%, 0.7 to 7.5%, 0.5 to 7.0%, 1.0 to 7.5%, or 1.5 to 7.5%, preferably 1.6 to 7.5%, and more preferably 1.7 to 7.0%, but is not particularly limited.

[0019] The average fiber length, average fiber diameter, fineness, Runkel ratio, cell wall thickness, curl, coarseness, average fibril circumference ratio, and average fibril area ratio can be measured using a Fiber Tester (manufactured by ABB).

[0020] -Bulk density- The bulk density of a cellulose material is usually 0.3 g / cm ３ or less, preferably 0.2 g / cm ３ or less, more preferably 0.1 g / cm ３ More preferably, 0.09 g / cm ３ Below, 0.05g / cm ３ The lower limit is usually 0.005 g / cm ３ or more, preferably 0.01 g / cm ３ Therefore, it is usually 0.005 to 0.3 g / cm ３ , preferably 0.005 to 0.2 g / cm ３ , more preferably 0.01 to 0.1 g / cm ３ , more preferably 0.01 to 0.09 g / cm ３ and is not particularly limited.

[0021] -Porosity- The porosity of a cellulose material is usually 80% or more, preferably 85% or more, more preferably 90% or more, 94% or more, and even more preferably 95% or more. The upper limit is usually 99% or less. Therefore, it is usually 80 to 99%, preferably 85 to 99%, more preferably 90 to 99%, and even more preferably 95 to 99%, but is not particularly limited. The porosity can be calculated using the formula: porosity = (1 - bulk specific gravity / true specific gravity) x 100.

[0022] - Maximum Torque Voltage (Floc) - The maximum torque voltage of the cellulose material is preferably 3,000 mV or more, 3,050 mV or more, or 3,080 mV or more, more preferably 3,300 mV or more, and even more preferably 3,500 mV or more. It is preferable that the above range be satisfied for cellulose materials derived from pulp-derived cellulose raw materials, particularly cellulose materials derived from pulp-derived cellulose raw materials other than sulfite pulp, such as kraft pulp and mechanical pulp. This allows for good cohesiveness and, as a result, good water absorption. The maximum torque voltage is the voltage at maximum torque when 300 mL of a 1% aqueous solution of each sample is rotated (300 rpm, 150 seconds, 25°C).

[0023] [2. Composition of Cellulosic Material] (Cellulosic Raw Material) Cellulosic materials are mainly composed of cellulose. The raw material of cellulose that constitutes the cellulose material is usually wood, and may be any of broad-leaved trees, softwoods, or a combination of two or more of these. Examples of broad-leaved trees include plants of the genus Beech (e.g., Fagus crenata), Tilia (e.g., Tilia japonica), Birch (e.g., Birch, Betula tremula), Populus (e.g., Poplar), Eucalyptus (e.g., Eucalyptus), Acacia (e.g., Acacia), Quercus (e.g., Quercus raja, Quercus phillyraeoides, Quercus serrata, Quercus acutissima), Maple (e.g., Acer palmatum), Kalopanax (e.g., Asiatic silver maple), Ulmus (e.g., Ulmus repens), Paulownia (e.g., Paulownia serrata), Magnolia (e.g., Magnolia obovata), Salix (e.g., Salix salicina), Aesculus (e.g., Aesculus buckex), Zelkova (e.g., Zelkova), Cornus (e.g., Cornus controversa), and Ash (e.g., Fraxinus japonica), with Eucalyptus plants being preferred. Conifers include, for example, cedars (e.g., Japanese cedar), spruce (e.g., Picea japonicus), larch (e.g., larch, western larch, tamarack), pine (e.g., black pine, Japanese white pine, radiata pine, eastern white pine), fir (e.g., Abies sachalinensis, fir, western fir), yew (e.g., taxus), arborvitae (e.g., juniper, yellow cedar), spruce (e.g., fir, fir, spruce, sitka spruce, eastern white pine), Examples of suitable cellulose raw materials include plants of the genus Podocarpus (e.g., Japanese spruce), genus Chamaecyparis (e.g., Japanese cypress, Japanese cypress, and Chamaecyparis sieboldii (beihi)), genus Podocarpus (e.g., Douglas-fir (Douglas-fir), Western hemlock), genus Thujopsis (e.g., Thujopsis dolabrata, Hiba), genus Tsuga (e.g., Tsuga sieboldii, Tsuga diversifolia), and genus Carpinus (e.g., Carpinus sieboldii). Among broad-leaved trees, preferred are plants of the genus Eucalyptus and Acacia. Among coniferous trees, preferred are plants of the genus Cryptomeria japonica, genus Pinus, genus Larix, and genus Chamaecyparis. On the other hand, non-woody materials such as bamboo, hemp, jute, kenaf, agricultural waste, and paper (e.g., recycled paper and printing paper) are also suitable. Virgin paper is preferred for its uniform quality.

[0024] The cellulose raw material is preferably a woody plant, more preferably a coniferous tree or a broad-leaved tree, and even more preferably a broad-leaved tree.

[0025] (Optional Components) The cellulose material may contain components other than cellulose. Examples of cellulose components include components other than cellulose derived from the cellulose raw material, by-products in the manufacturing process, and optional additives (e.g., storage stabilizers, additives used in pulp or paper manufacturing, etc.). Examples of components derived from the cellulose raw material include monosaccharides (e.g., trioses such as aldotriose and ketotriose; tetraoses such as erythrose, threose, and erythrulose; pentoses such as xylose, ribose, arabinose, lyxose, ribulose, and xylulose; hexoses such as mannose, allose, altrose, glucose, gulose, idose, galactose, talose, psicose, fructose, sorbose, tagatose, fucose, fructose, and rhamnose; and heptoses such as sedoheptulose). , oligosaccharides (e.g., disaccharides such as sucrose, lactose, maltose, trehalose, turanose, and cellobiose; trisaccharides such as raffinose, melezitose, and maltotriose; tetrasaccharides such as acarbose and stachyose; oligosaccharides such as xylooligosaccharides, cellooligosaccharides, fructooligosaccharides, galactooligosaccharides, and mannanoligosaccharides); polysaccharides (e.g., glycogen, starch (amylose and amylopectin), cellulose, hemicellulose, dextrin, and glucan); reducing sugars, modified sugars, and lignins. Examples of by-products include sodium sulfate, sodium sulfite, sodium chloride, magnesium sulfate, magnesium sulfite, magnesium chloride, calcium sulfate, calcium sulfite, calcium chloride, ammonium sulfate, ammonium sulfite, ammonium chloride, and sodium hydroxide; and inorganic fillers and pigments for coated or uncoated paper such as calcium carbonate and kaolin.

[0026] The optional additives may be any components commonly used in the intended use of the cellulosic material, depending on the intended use, and include, for example, additives such as bases, carriers, solvents, dispersants, emulsifiers, buffers, stabilizers, excipients, binders, disintegrants, lubricants, thickeners, moisturizers, colorants, fragrances, chelating agents, etc. Furthermore, when the cellulosic material contains additives that are added during pulp or paper production, these additives may also be used.

[0027] When the cellulose material contains components other than cellulose, the content (% by weight based on the dry weight) of these components varies depending on the type of cellulose raw material, production conditions, etc., and is therefore difficult to define unambiguously. However, it is preferable that the content be small, for example, 10% by weight or less, 8% by weight or less, 5% by weight or less, 1% by weight or less, 0.1% by weight or less, or 0.01% by weight or less, preferably below the detection limit, and more preferably 0% by weight.

[0028] (Moisture Content) The cellulose material may contain moisture. When the cellulose material contains moisture, the ratio of the amount of moisture to the weight of the cellulose material (moisture content) is usually 20% by weight or less, preferably 19% by weight or less, more preferably 18% by weight or less, and even more preferably 17% by weight or less, 16% by weight or less, or 15% by weight or less. The lower limit is not particularly limited, and may be 0% by weight.

[0029] [3. Method for Producing Cellulose Material] The method for producing a cellulose material is not particularly limited, but an example includes a method that includes producing pulp, a pulp sheet, or paper from a cellulose raw material and, if necessary, adjusting the pulp, pulp sheet, or paper to have the above-mentioned shape. By adjusting the type of raw material and the production conditions, a cellulose material that satisfies the above-mentioned parameters can be obtained.

[0030] [3.1 Pulp Production] Pulp may be produced by a conventional method, for example, by preparing chips of a cellulose raw material and obtaining pulp from the chips.

[0031] For example, when the cellulose raw material is a woody plant, the chips can be prepared by removing the bark from the woody parts (e.g., trunks and branches) and crushing them to obtain chips. The cellulose raw material may be one type or a combination of two or more types.

[0032] The conditions or techniques for producing pulp are not particularly limited as long as they include the step of pulping the wood chips described above. Pulping methods include, but are not limited to, chemical methods (chemical pulping) that involve cooking, such as the Kraft method, sulfite method, soda method, and polysulfide method; mechanical methods (mechanical pulping) that use equipment such as refiners and grinders; and methods of pulping by mechanical force after chemical pretreatment (semi-chemical pulping). Further treatments such as bleaching, beating, and defibration may also be performed. The resulting pulp may be unbleached (unbleached) pulp, bleached (bleached) pulp, beaten pulp, unbeaten pulp, or fluff pulp. Examples of chemical pulps include sulfite pulp and kraft pulp. Pulp is classified according to the treatment process into unbleached softwood kraft pulp (NUKP), bleached softwood kraft pulp (NBKP), unbleached hardwood kraft pulp (LUKP), bleached hardwood kraft pulp (LBKP), dissolving kraft pulp (DKP), unbleached hardwood sulfite pulp (LUSP), bleached hardwood sulfite pulp (LBSP), oxygen-delignified hardwood kraft pulp (LOKP), unbleached softwood kraft pulp (NUKP), bleached softwood kraft pulp sheet (NBKP), unbleached softwood sulfite pulp (NUSP), bleached softwood sulfite pulp (NBSP), and recycled pulp. Mechanical pulp is further classified into types such as groundwood pulp (GP), pressure groundwood pulp (PGW), refiner groundwood pulp (RGP), thermomechanical pulp (TMP), chemithermomechanical pulp (CTMP), bleached chemithermomechanical pulp (BCTMP), alkaline hydrogen peroxide thermomechanical pulp (APTMP), etc. Among these, pulp derived from conifers (e.g., NUKP, NBKP, NUSP, NBSP, NUCTMP, NBCTMP) is preferred.

[0033] [3.2 Production of Pulp Sheets and Paper] Pulp sheets and paper can be produced from pulp by conventional methods. Pulp may be derived from the above-mentioned cellulose raw materials. Pulp raw materials may be, for example, broadleaf trees, coniferous trees, or combinations of two or more of these, with coniferous trees being preferred. Pulp sheets and paper can be produced, for example, according to Japanese Industrial Standards (JIS) P 8222:2015, "Pulp - Method for Preparing Test Handsheets," including a method including a step of forming pulp into a sheet using a paper machine or the like according to conventional methods. When forming pulp into a sheet, additives commonly used in papermaking applications may be added to the pulp. Examples of such additives include paper strength agents, bulking agents, pigments, fillers, retention aids, drainage aids, internal sizing agents (rosin-based sizing agents, aluminum sulfate, etc.), pH adjusters, antifoaming agents, pitch control agents, and slime control agents. The amount of the additive used is not particularly limited, as long as it does not impair the effects of the present invention. The basis weight and thickness of the sheet are not particularly limited. When forming the sheet, paper raw materials other than pulp may be used, such as other materials such as rayon fiber and film. The paper raw material may be pulp obtained from the above plants together with other materials pre-formed into a shape such as a sheet, film, or roll. The paper may also be waste paper, newsprint, or printing paper (e.g., high-quality paper, plain paper, or coated paper). The paper may or may not contain a filler. Fillers commonly used in acidic, neutral, or alkaline papermaking can be used as the filler, and are not particularly limited. For example, in pseudo-neutral papermaking, neutral papermaking, and alkaline papermaking, inorganic fillers such as clay, calcined kaolin, delaminated kaolin, heavy calcium carbonate, light calcium carbonate, light calcium carbonate-silica composite, magnesium carbonate, barium carbonate, titanium dioxide, zinc oxide, silicon oxide, amorphous silica (white carbon, etc.), aluminum hydroxide, calcium hydroxide, magnesium hydroxide, and zinc hydroxide, organic fillers such as urea-formalin resin, polystyrene resin, phenolic resin, and hollow microparticles, and combinations of two or more selected from these can be used. In acidic papermaking, fillers other than those used in neutral papermaking that are acid-soluble (e.g., amorphous silica and titanium dioxide) can be used.

[0034] [3.3 Shape Adjustment] The shape of the cellulose material can be adjusted by treatments such as dehydration, pulverization, maceration, beating, disintegration, a combination of two or more selected from these, etc. Which treatments to perform (including the order in the case of two or more treatments) can be appropriately selected based on the type of cellulose raw material, whether it is pulp, pulp sheet, or paper, and by referring to the measured values ​​of each parameter before treatment, etc.

[0035] (Dehydration) By subjecting pulp (wet pulp) or pulp sheet (wet pulp sheet) to a dehydration treatment, the moisture content of the cellulose material can be adjusted and its shape can be easily adjusted (for example, to a cotton-like or soybean pulp refuse-like shape). Examples of dehydration treatments include freeze drying, spray drying, tray drying, drum drying, belt drying, a method in which the cellulose is thinly spread on a glass plate or the like and dried, fluidized bed drying, microwave drying, heated fan-type reduced pressure drying, and reduced pressure (degassing) drying. The dehydration treatment can be carried out using dehydration equipment such as a dehydrator or dryer. Examples of dehydration equipment include screw presses, centrifuges (centrifugal dehydrators), belt presses, tube presses, rotary presses, airflow dryers (e.g., airflow dryers equipped with rotating blades, such as airflow dryers with built-in classifiers), air blast dryers (e.g., stationary air blast dryers), microwave dryers, vacuum dryers, fluidized bed dryers, and freeze dryers. Of these, screw presses, airflow dryers, and air blast dryers are preferred. One or more dehydration equipment may be used. For example, a screw press is applied to pulp (wet pulp) to reduce the moisture content of the wet pulp, typically to about 70% or less, preferably to about 65% or less. Subsequently, dehydration using an airflow dryer (preferably an airflow dryer with built-in classifier) ​​can produce a cotton-like cellulose material with a moisture content of 20% or less. As another example, pulp (wet pulp) can be dehydrated using a screw press and then dehydrated using an air blast dryer (preferably a stationary air blast dryer). This allows the preparation of an okara-like cellulose material with a moisture content of 20% or less. The temperature conditions for drying and dehydration vary depending on the dehydration equipment, but are usually 300°C or less, preferably 200°C or less, more preferably 100°C or less, and even more preferably 70°C or less, 60°C or less, or 50°C or less. There is no particular lower limit, and freeze-drying may be performed at the freezing temperature, while other drying methods may be performed at room temperature (e.g., 15 to 30°C).

[0036] (Pulverization) Pulverization can be performed on paper (preferably cut paper) to obtain FSP. As another example, pulp can be obtained by performing the process on a dry pulp sheet (preferably by performing a two-stage pulverization process). Examples of pulverizers include cutting mills, impact mills, airflow mills, hammer mills, roll mills, roller mills, media mills, media agitation mills, and freeze pulverizers, and these can be used alone or in combination.

[0037] Examples of cutting-type mills include 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), pulp crushers (manufactured by Zuiko Co., Ltd.), and Wonder Crusher (manufactured by Osaka Chemical Co., Ltd.). For the crushing process of paper (including waste paper), it is preferable to use a cutting-type mill. This makes it possible to easily obtain FSP.

[0038] 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.).

[0039] 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 those manufactured by Soso 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.), Wiley Crusher (manufactured by Sanki Manufacturing Co., Ltd.), Pulp Crusher (manufactured by Zuiko Co., Ltd.), Jacobson Fine Pulverizer (manufactured by Kobe Steel Pantech Co., Ltd.), Universal Mill (manufactured by Tokuju Manufacturing Co., Ltd.), and Continuous Vibro Mill (Eurus Techno Co., Ltd.).

[0040] Examples of airflow mills include a 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 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).

[0041] Examples of roller mills include a vertical roller mill (manufactured by Sinion Co., Ltd.), a roller mill (manufactured by Kotobuki Giken Kogyo Co., Ltd.), a VX mill (Kurimoto Iron Works Co., Ltd.), a KVM-type vertical roller mill (Earth Technica Co., Ltd.), and an IS mill (IHI Plant Engineering Co., Ltd.). Of these, impact mills, hammer mills, and roller mills are preferred.

[0042] (Disintegration) The disintegration treatment may be any treatment that disintegrates a material to be treated (e.g., pulp, a pulp sheet, preferably pulp (wet pulp)) into fibers, and a disintegrator such as a high-concentration disintegrator, a standard disintegrator, or a high-speed disintegrator may be used. The disintegration treatment is preferably performed in combination with a subsequent dehydration treatment (more preferably, dehydration treatment using a centrifugal dehydrator or a static air-blowing dryer) and / or a crushing treatment (more preferably, dehydration treatment using a centrifugal dehydrator, crushing treatment, and dehydration treatment using a static air-blowing dryer, in this order). This makes it easy to adjust the moisture content of the cellulosic material, and to easily obtain a soybean pulp-like cellulosic material. Disintegration may be performed in accordance with JIS P8220-2:2012.

[0043] (Beating) The beating process may be any process that applies shear force to fibers contained in a material to be treated (e.g., pulp, a pulp sheet, preferably pulp), and a beating device such as a refiner (e.g., a disk-type, conical-type, or cylindrical-type) may be used. The beating process is preferably performed on an aqueous dispersion of dry pulp (e.g., a solids content of 10% by weight or less, 9% by weight or less, 8% by weight or less, 7% by weight or less, 6% by weight or less, or 5% by weight or less, with the lower limit usually being 1% by weight or more). The beating process is preferably performed in combination with a subsequent dehydration process and / or crushing process (more preferably, dehydration process using a centrifugal dehydrator, crushing process, and dehydration process using a static air-blowing dryer, in that order). This facilitates adjustment of the moisture content of the cellulosic material, making it easy to obtain a soybean-pulverized cellulosic material.

[0044] (Disintegration (Fibrillation)) Disintegration (fibrillation) may be any process that loosens the fibers that make up the object to be treated (e.g., pulp, pulp sheet, paper, preferably pulp sheet (dry pulp sheet) or paper) without substantially cutting them, and can be performed using a defibrator such as a wet pulp defibrator, a pulp defibrator, or a dry defibrator. Preferably, a pulp sheet (dry pulp sheet) or paper may be subjected to the disintegration process. This allows for a cotton-like cellulosic material to be obtained. On the other hand, pulp (wet pulp) may be subjected to a disintegration process (after maceration and dehydration as necessary), preferably followed by a dehydration process. This allows for efficient production of an okara-like cellulosic material. When defibrating dry pulp, it is preferable to use a dry defibrator. The physical properties of the cellulosic material can be easily adjusted by adjusting the screen diameter of the defibrator and the number of times of treatment. For example, after roughly defibrating the material using a screen with a large diameter (for example, 15 mm or more, preferably 20 mm or more), the material is defibrated again using a screen with a small diameter (for example, 8 mm or less, preferably 5 mm or less), which allows efficient production of a cotton-like cellulosic material.

[0045] (Cutting) Cutting is usually performed on paper, and can be performed using a cutting machine such as a shredder. The size after cutting is usually 1 to 8 mm x 15 to 40 mm, preferably 2 to 6 mm x 18 to 35 mm, and more preferably 2 to 5 mm x 20 to 30 mm. By cutting the paper and then pulverizing it (for example, by pulverizing it with a cutting-type mill), a cotton-like cellulose material can be efficiently obtained.

[0046] (Pretreatment) Prior to each of the above treatments, pulp (for example, dry pulp such as mechanical pulp, kraft pulp, sulfite pulp, etc.) may be immersed in water (wetted) as needed.

[0047] [4. Uses (Water Absorbent)] When cellulose materials are brought into contact with a substance containing a liquid component, they can absorb the liquid component, reduce the fluidity of the substance, and improve its strength, and therefore can be used as water absorbents (water absorbents; flocculants, solidification agents) in various fields such as civil engineering and construction. For example, this can improve the quality of the processed substance, increase reusability, improve workability, and reduce the difficulty of waste disposal.

[0048] Examples of materials containing liquid components include soil with a high water content (mud, clay, inorganic sludge), soft ground, and other industrial waste. Examples of soil with a high water content include construction waste soil (excavated soil generated by tunnel shield construction, dredging work in rivers and oceans, bank protection work, etc.); and washed mud generated in the crushing industry, lime mining, etc. The liquid component is not particularly limited, and may be water or any liquid component.

[0049] The amount of cellulose material added to a substance containing a liquid component is usually 1% by weight or more, preferably 5% by weight or more, more preferably 10% by weight or more, and even more preferably 15% by weight or more, based on 100% by weight of the target substance, but is not particularly limited. The upper limit is usually 90% by weight or less, preferably 80% by weight or less, and more preferably 70% by weight or less.

[0050] EXAMPLES The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these.

[0051] Example 1 LOKP Flocculent Pulp Hardwood oxygen-delignified kraft pulp (LOKP: unbeaten wet pulp) was dewatered using a screw press and then dried using a Drymeister (registered trademark, manufactured by Hosokawa Micron Corporation), an airflow dryer with a built-in classifier, operated continuously for 1 hour at an inlet temperature of 200°C and an outlet temperature of 70°C to prepare flocculent pulp with a moisture content of less than 15% by weight.

[0052] Example 2 Copy Paper FSP (Fine Shredded Paper) Copy paper (Super Economy + A4, basis weight approximately 68 g / m ２110 g of paper (equivalent to 58.5 kg in 46-size paper, paper thickness 0.09 mm, Askul Corporation) was shredded into 3 x 25 mm pieces using an office shredder (Nakabayashi Co., Ltd.). The shredded waste was then pulverized using a cutting mill to obtain copy paper FSP with a moisture content of less than 7% by weight.

[0053] Example 3: LOKP Okara-like Pulp Hardwood oxygen delignified kraft pulp (LOKP: unbeaten wet pulp) was dewatered using a screw press and then dried for 24 hours in a static air-blowing dryer (manufactured by Yamato Scientific Co., Ltd.) set at 50°C to prepare an Okara-like pulp with a moisture content of less than 12% by weight.

[0054] Example 4 NUKP Okara-like Pulp Unbleached softwood kraft pulp (NUKP: unbeaten wet pulp) was disintegrated in a high-concentration disintegrator (manufactured by Kumagaya Riki Kogyo Co., Ltd.), adjusted in a centrifugal dehydrator so that the solid content was 30% by weight, defibrated in a wet pulp defibrator (manufactured by Kumagaya Riki Kogyo Co., Ltd.), and then dried for 24 hours in a static air-blowing dryer (manufactured by Yamato Scientific Co., Ltd.) set at 50°C to prepare an okara-like pulp with a moisture content of less than 12% by weight.

[0055] Example 5: Canadian softwood BCTMP okara-like pulp BCTMP (West Fraser: block form) with a brightness of 75% was cut into a block weighing approximately 1 kg, and the resulting block was immersed in water for 1 hour and then defibrated in a high-concentration defibrator (Kumagaya Riki Kogyo Co., Ltd.). The pulp was then adjusted in a centrifugal dehydrator to a solids content of 30% by weight, defibrated in a wet pulp defibrator (Kumagaya Riki Kogyo Co., Ltd.), and dried for 24 hours in a static air-blowing dryer (Yamato Scientific Co., Ltd.) to prepare an okara-like pulp with a moisture content of less than 12% by weight.

[0056] Example 6: NBKP crushed flocculent pulp A softwood bleached kraft dry pulp sheet (NBKP) was roughly crushed using a defibrator (ATOMZ M4-300, manufactured by Ishikawa Soken Co., Ltd., screen diameter φ25 mm), and the resulting roughly crushed material was further treated using a defibrator (ATOMZ M4-300, manufactured by Ishikawa Soken Co., Ltd., screen diameter φ4.5 mm) to prepare flocculent pulp with a moisture content of less than 8% by weight.

[0057] Example 7 LUSP Okara-like Pulp Unbleached hardwood sulfite pulp (LUSP: wet pulp) was disintegrated in a high-concentration disintegrator (manufactured by Kumagaya Riki Kogyo Co., Ltd.), adjusted in a centrifugal dehydrator so that the solid content was 30% by weight, defibrated in a wet pulp defibrator (manufactured by Kumagaya Riki Kogyo Co., Ltd.), and then dried for 24 hours in a static air-blowing dryer (manufactured by Yamato Scientific Co., Ltd.) set at 50°C to prepare an Okara-like pulp with a moisture content of less than 12% by weight.

[0058] Example 8 NUSP Okara-like Pulp Unbleached softwood sulfite pulp (NUSP: wet pulp) was disintegrated in a high-concentration disintegrator (manufactured by Kumagaya Riki Kogyo Co., Ltd.), adjusted in a centrifugal dehydrator to a solids content of 30% by weight, defibrated in a wet pulp defibrator (manufactured by Kumagaya Riki Kogyo Co., Ltd.), and then dried for 24 hours in a static air-blowing dryer (manufactured by Yamato Scientific Co., Ltd.) set at 50°C to prepare an Okara-like pulp with a moisture content of less than 12% by weight.

[0059] Example 9 Beaten LOKP Okara-like Pulp A hardwood oxygen delignified kraft wet pulp sheet (LOKP) was dispersed in water to prepare a 4 wt% aqueous dispersion, which was then processed in a single-disc refiner (manufactured by Aikawa Iron Works Co., Ltd.) and beaten to a Canadian Standard Freeness (CSF) of 400 ml. The dispersion was then adjusted to a solids content of 30% by weight using a centrifugal dehydrator, defibrated using a wet pulp defibrator (manufactured by Kumagai Riki Kogyo Co., Ltd.), and dried for 24 hours in a static air-blowing dryer (manufactured by Yamato Scientific Co., Ltd.) set at 50°C to prepare an Okara-like pulp with a moisture content of less than 12 wt%.

[0060] Example 10: Beaten NUKP Okara-like Pulp A softwood unbleached kraft wet pulp sheet (NUKP) was dispersed in water to prepare a 3 wt% aqueous dispersion, which was then processed in a single-disc refiner (manufactured by Aikawa Iron Works Co., Ltd.) and beaten to a Canadian Standard Freeness (csf) of 400 ml. The dispersion was then adjusted to a solids content of 30% by weight using a centrifugal dehydrator, defibrated using a wet pulp defibrator (manufactured by Kumagai Riki Kogyo Co., Ltd.), and dried for 24 hours in a static air-blowing dryer (manufactured by Yamato Scientific Co., Ltd.) set at 50°C to prepare an Okara-like pulp with a moisture content of less than 12 wt%.

[0061] Example 11: Okara-like pulp from Canadian hardwood BCTMP The procedure of Example 5 was repeated except that hardwood BCTMP (West Fraser R350B80: block type) was used instead of the BCTMP, to prepare an okara-like pulp having a moisture content of less than 10% by weight.

[0062] Example 12: Okara-like pulp from Canadian softwood BCTMP The procedure of Example 5 was repeated except that hardwood BCTMP (West Fraser R400B80: block type) was used instead of the BCTMP, to prepare an okara-like pulp having a moisture content of less than 12% by weight.

[0063] Example 13: Cotton-like pulp from recycled newspaper. Recycling newspaper was cut into 15 mm x 15 mm pieces and crushed using a Wonder Crusher WC-3 (manufactured by Osaka Chemical Co., Ltd.) to obtain cotton-like pulp from recycled newspaper having a moisture content of less than 10% by weight.

[0064] Example 14: Copier paper cotton pulp Instead of recycled newspaper, copy paper (super economy + A4, basis weight approximately 68 g / m) was used. ２ The same procedure as in Example 13 was carried out except that a paper weight of 58.5 kg in 46-size equivalent, paper thickness of 0.09 mm, manufactured by Askul Corporation was used, to obtain a cotton-like pulp for copying paper having a moisture content of less than 10% by weight.

[0065] Example 15 Newsprint flocculant pulp Newsprint flocculant pulp having a moisture content of less than 10% by weight was obtained in the same manner as in Example 13, except that newsprint was used instead of recycled newspaper.

[0066] Example 16: Unfilled Paper Flocculant Pulp Unfilled paper flocculant pulp having a moisture content of less than 10% by weight was obtained in the same manner as in Example 13, except that unfilled paper was used instead of recycled newspaper.

[0067] Example 17 LBKP dry sheet flocculent pulp An LBKP dry sheet flocculent pulp having a moisture content of less than 10% by weight was obtained in the same manner as in Example 13, except that a hardwood bleached kraft dry pulp sheet (LBKP) was used instead of recycled newspaper.

[0068] Example 18 NUKP dry sheet flocculent pulp The same procedure as in Example 13 was carried out except that softwood unbleached kraft dry pulp sheet (NUKP) was used instead of recycled newspaper, to obtain NUKP dry sheet flocculent pulp having a moisture content of less than 10% by weight.

[0069] Example 19: Fluff pulp crusher product The same procedure as in Example 13 was carried out except that a softwood fluff pulp dry sheet (manufactured by International Paper, an unreacted product) was used instead of recycled newspaper, and a fluff pulp crusher product with a moisture content of less than 10% by weight was obtained.

[0070] Comparative Example 1 FSP derived from waste paper Waste paper with a moisture content of less than 9% by weight was crushed in two stages using a cutter mill, and FSP with a fine content of more than 80% was selected and used as the sample for Comparative Example 1.

[0071] Comparative Example 2 LOKP Pulp Powder The LOKP flocculent pulp of Example 1 was mechanically pulverized in a Tornado Mill (manufactured by Nikkiso Co., Ltd.) so that the fine content exceeded 80% to prepare a pulp powder.

[0072] [Measurement of physical properties] The cellulose materials obtained in the examples and comparative examples were measured for the physical properties shown in Tables 1 to 3. The respective measurement conditions were as follows.

[0073] The average fiber length, average fiber width, fineness, Runkel ratio, fiber wall thickness, curl, coarseness, average fibril perimeter ratio, and average fibril area ratio were measured using an L&W Fiber Tester (manufactured by ABB).

[0074] The bulk density was calculated by gently placing each sample into a 2000 mL measuring cylinder, measuring the weight, and dividing the weight by the volume.

[0075] The porosity was calculated by the formula (1 - pulp bulk density / pulp true density) x 100. The bulk density was calculated by the method described above. The true density was measured using a dry density meter (Shimadzu Corporation).

[0076] The maximum torque voltage was measured using a Flocking Tester (manufactured by Koei Kogyo Co., Ltd.) by rotating 300 mL of a 1% aqueous solution of each sample at 300 rpm for 150 seconds at 25° C. The higher the maximum torque voltage, the greater the degree of cohesion.

[0077] [Water Absorption Test] 3 g of sample was placed in a bag-shaped nonwoven fabric (polyethylene, 70 mm x 95 mm), the top folded back, and stapled to prepare a test specimen. Degassed water and the test specimen were placed in a 500 mL beaker, and the mixture was stirred at 300 rpm using a magnetic stirrer (20 mm) in a constant temperature and humidity chamber (temperature 20 ° C, humidity 60%) for 24 hours to absorb water. During the stirring process, the stirrer was covered with a wire frame to prevent contact between the test specimen and the stirrer. The water temperature was adjusted to 19 ° C. After water absorption, the test specimen was left to dry in the air for 10 minutes, weighed, and the water absorption of the sample was calculated by subtracting the water absorption of the nonwoven fabric (N = 1).

[0078]

[0079]

[0080]

[0081] Compared with the comparative samples having an average fiber length of less than 0.40 mm, an average aspect ratio of less than 20, and fines exceeding 80%, the example samples having an average fiber length of 0.40 mm or more, an average aspect ratio of 20 or more, fines of 80% or less, and a moisture content of 20% or less all had high water absorption and good water absorption (Tables 1 to 3). These results demonstrate that the water-absorbing material of the present invention exhibits good water absorption and is useful as a material for treating mud or inorganic sludge.

Claims

1. A cellulose-based absorbent material for the civil engineering or construction industry, comprising a cellulose material having an average fiber length of 0.40 mm or more, an average aspect ratio of 20 or more, a proportion of fibers with a fiber length of 0.2 mm or less of 80% or less, and a moisture content of 20% by weight or less.

2. The water absorbent material for civil engineering or construction use according to claim 1, wherein the average fiber length of the cellulose material is 0.60 mm or more.

3. A water absorbent material for civil engineering or construction use according to claim 1 or 2, wherein the average aspect ratio of the cellulose material is 22 or more.

4. A water absorbent material for civil engineering or construction use according to claim 1 or 2, wherein the Runkel ratio of the cellulose material is 0.28 or more.

5. The water absorbent material for civil engineering or construction use according to claim 1 or 2, wherein the curl of the cellulose material is 12.5% ​​or more.

6. A water absorbent material for civil engineering or construction use according to claim 1 or 2, wherein the roughness of the cellulose material is 105 μg / m or more.

7. A water absorbent material for civil engineering or construction use according to claim 1 or 2, wherein the porosity of the cellulose material is 94% or more.

8. The bulk density of the cellulose material is 0.1 g / cm ３ 3. The water absorbent material for civil engineering or construction according to claim 1 or 2, which is as follows:

9. A water absorbent material for civil engineering or construction use according to claim 1 or 2, wherein the average fibril area ratio of the cellulose material is 1.5% or more.

10. The water absorbent material for civil engineering or construction use according to claim 1 or 2, wherein the cellulose material is derived from broadleaf trees.